JP2825679B2 - Electrophotographic photoreceptor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member and a method for producing the same, and more particularly, to an electrophotographic photosensitive member having a photosensitive layer containing two or more specific compounds and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Numerous organic photoconductors have been developed since the discovery that certain organic compounds exhibit photoconductivity. For example, poly-N-vinylcarbazole,
Organic photoconductive polymers such as polyvinyl anthracene,
Low molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, arylalkanes, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments,
Organic pigments and dyes such as indigo dye, thioindigo dye and squaric acid methine dye are known.

[0003] In particular, organic pigments and dyes having photoconductivity are easier and cheaper to synthesize than inorganic materials, and the variety of compounds that can be used has been expanded. Pigments and dyes have been proposed as charge generating materials for photoreceptors.

In recent years, as the durability of photoreceptors has been extended and the image quality has been further improved, in addition to the characteristics such as high sensitivity and high durability conventionally required of the charge generation material, the durability against the inactive memory phenomenon has attracted attention. ing.

The rest memory phenomenon is basically one of the deterioration phenomena due to corona products. When the rotation of the photoconductor is stopped after the copy is completed, the charging ability of the portion stopped near the corona charger is reduced. In the case of the forward development, the image density decreases only in that portion, and in the case of the reverse development, the image density increases. This phenomenon tends to occur after the photoconductor has been used for a long period of time, and has become a more serious problem as the life of the photoconductor is extended.

An organic photoconductive substance is a material which has a relatively high degree of freedom in molecular design and can be designed for spectral sensitivity, but is used for a laser beam printer, a laser facsimile, etc., which have recently received special attention. 780-80
Organic photoconductive materials having sufficient sensitivity to semiconductor laser light having an oscillation wavelength near 0 nm cannot be said to be abundant, and their spectral sensitivity ranges are limited.

For example, when designing an electrophotographic photoreceptor to satisfy the combined functions of both a plain paper copier and a laser beam printer or a laser facsimile, 40
A broad and sufficient spectral sensitivity is required from the visible region around 0 nm to the infrared region around 800 nm, which is the wavelength range of a semiconductor laser. One such charge-generating substance must have such spectral sensitivity. Is very difficult.

[0008]

Therefore, a combination of a plurality of charge-generating substances having sensitivity in different wavelength ranges, such as a substance having excellent sensitivity to visible light and a substance having excellent sensitivity to long-wavelength light, is used. GB-A148 can be used
4927, it has been very difficult to bring a plurality of materials into an appropriate mixed state in the photosensitive layer in the following points.

That is, the photosensitive layer is usually formed by applying a coating solution containing an organic photoconductive material, a binder resin and a solvent on a conductive support. When present in the coating liquid, the charge generating substance causes aggregation due to the difference in potential of each, and as a result, sedimentation occurs, or the charge generating substance undergoes crystal transformation due to a difference in the appropriate solvent, and is stable. It was difficult to make all the charge generating substances exist in the state.

In the case where a coating solution is prepared for each charge generating substance and applied in order by a dip coating method, depending on the binder resin and solvent used, the lower charge generating layer may be dissolved and become stable. No electrophotographic properties could be obtained.

Further, when a curable resin is used for the layer containing the charge generating substance in order to prevent the above drawbacks, it is difficult to make the resin three-dimensional because the charge generating substance is contained in the resin. Even if this is the case, there are problems such as an increase in resistance and poor electrophotographic characteristics, and in the case where a curing agent or the like is contained, poor electrophotographic characteristics.

An object of the present invention is to provide an electrophotographic photosensitive member having stable electrophotographic characteristics over a wide range from a short wavelength region to a long wavelength region, and a method of manufacturing the same.

Another object of the present invention is to provide an electrophotographic photosensitive member having high durability against a photo memory and a pause memory, and a method for manufacturing the same.

[0014]

That is, according to the present invention, at least the following formula (1) is provided on a conductive support.

[0015]

Embedded image (Wherein, Ar ₁ is a hydrocarbon aromatic ring which may have a substituent, a heteroaromatic ring which may have a substituent, or the aromatic ring is directly or an aromatic group or a non-aromatic group. represents a divalent group derived from the union with a group, R ₁ and R
₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group. And a compound represented by the following formula (2):

[0016]

Embedded image (In the formula, Ar ₂ represents a hydrocarbon aromatic ring which may have a substituent, a heteroaromatic ring which may have a substituent, or an aromatic group which is directly or aromatic or non-aromatic. And R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group. And the photosensitive layer is a layer formed by spray-coating the compound represented by the formula (1) and the compound represented by the formula (2) by different spraying devices. An electrophotographic photoreceptor, characterized in that:

Further, the present invention is a method for producing the above electrophotographic photosensitive member.

The photosensitive layer of the electrophotographic photosensitive member of the present invention contains the compounds represented by the above formulas (1) and (2).

In the formula (1), the compounds from which Ar ₁ is derived include hydrocarbon aromatic rings such as benzene, naphthalene, fluorene, phenanthrene, anthracene and pyrene, furan, thiophene, pyridine, indole, benzothiazole and carbazole. , Acridone, dibenzothiophene, benzoxazole, benzotriazole, heteroaromatic rings such as oxadiazole and thiazole, and those in which the above aromatic ring is bonded directly or by an aromatic group or a non-aromatic group, for example, triphenylamine , Diphenylamine, N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylamine Enirumetan, diphenyl sulfone, diphenyl ether, benzophenone, stilbene, distyryl benzene, tetraphenyl -p- phenylenediamine and tetraphenyl benzidine and the like.

Examples of the substituent which Ar ₁ may have include alkyl groups such as methyl, ethyl, propyl and butyl, alkoxy groups such as methoxy and ethoxy, dialkylamino groups such as dimethylamino and diethylamino, fluorine atom, chlorine Halogen atom such as atom and bromine atom, hydroxy group, nitro group, cyano group and halomethyl group.

Examples of the halogen atom represented by R ₁ and R ₂ include a fluorine atom, a chlorine atom and a bromine atom, examples of the alkyl group include methyl, ethyl, propyl and butyl groups, and examples of the alkoxy group include methoxy and ethoxy. And the like.

In the formula (2), the compound from which Ar ₂ is derived and the substituent that Ar ₂ may have are the same as the compound from which Ar ₁ is derived and the substituent that Ar ₁ may have. R ₃ , R ₄ and R ₅ are also the same as R ₁ and R ₂ .

Specific examples of the compound represented by the formula (1) are shown below, but it should not be construed that the invention is limited thereto.

[0024]

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[0025]

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[0026]

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[0027]

Embedded image Of these, (1) -1, (1) -2 and (1)-
3 is preferable, and (1) -2 is particularly preferable.

Specific examples of the compound represented by the general formula (2) include the following, but are not limited thereto.

[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

Embedded image Of these, (2) -1, (2) -2, (2) -3,
(2) -4, (2) -5 and (2) -6, especially (2)
-1 is preferred.

The photosensitive layer in the present invention may be a so-called single layer type in which a charge generating substance and a charge transporting substance are contained in the same layer.
A so-called lamination type in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport substance may be laminated, but the latter is more preferable. Further, it is more preferable that the charge generation layer has a laminated structure of layers for each charge generation substance contained.

In this case, in the present invention, the layer containing the compound represented by the formula (1) having excellent sensitivity in the visible light range is formed by using a layer containing the compound represented by the formula (1) in a wavelength range in which the compound having the excellent sensitivity is excellent. Also, it is preferable to laminate on a layer containing the compound represented by the formula (2) having excellent sensitivity in a long wavelength region.

Hereinafter, the laminated photoconductor will be described in more detail.

The charge generation layer of the present invention can be formed by dispersing the compounds represented by formulas (1) and (2) in a suitable binder resin using a solvent, and applying this dispersion. In the present invention, a known charge generating substance other than the compounds represented by the formulas (1) and (2) may be further used.

The binder resin can be selected from a wide range of insulating resins or organic photoconductive polymers. For example, as the insulating resin, polyvinyl butyral, polyarylate (condensed polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, acrylic resin,
Polyacrylamide resin, polyamide, cellulosic resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and the like. Organic photoconductive polymers include carbazole, polyvinyl anthracene, and polyvinyl pyrene.

The content of the resin in the charge generation layer is preferably not more than 80% by weight based on the total weight of the charge generation layer.
It is preferably 0% by weight or less.

The solvent used for the coating for the charge generating layer is selected from the solubility and dispersion stability of the resin and the charge transporting material used, and is usually alcohols, sulfoxides, ethers, esters, aliphatic halogenated compounds. Hydrocarbons or aromatic compounds can be used.

The thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.01 μm to 2 μm. This in dry weight of the paint when about 10mg / m ² ~2000mg / m ²
Equivalent to the degree.

In the present invention, the charge generation layer is formed by spray coating using a different spray device for each type of charge generation material.

FIGS. 1 and 2 show examples of a coating apparatus having such a spray apparatus.

The spray devices 1 and 2 are supplied with a coating solution containing a charge generating material having excellent sensitivity in different wavelength ranges. The spray devices 1 and 2 can be adjusted to any spray state, discharge amount and discharge angle,
It is raised and lowered by the lifting device 3. In addition, since the conductive support 4 rotates in the direction of the arrow, uniform and appropriate coating can always be performed, and this device can provide an arbitrary and preferable coating as a photosensitive layer.

For example, in the coating apparatus shown in FIG. 1, the spraying device 1 prevents the paint discharged from the spraying device 1 and the paint discharged from the spraying device 2 from mixing at all before and after reaching the conductive support. If 2 is set, the two types of paints are laminated in two layers without mixing. Conversely, the spray devices 1 and 2 are such that the two paints are thoroughly mixed before reaching the conductive support.
Is set, a layer containing two types of charge generating substances in a single layer can be formed. Of course, an intermediate layer between a laminated layer and a single layer can be formed. FIG.
In the coating device described in (1), the coating film can be formed into a laminated structure of two or more layers by rotating the conductive support at an appropriate speed.

As described above, according to the present invention, since it is not necessary to mix a plurality of charge generating substances before coating, the above-mentioned problems, namely, aggregation of different charge generating substances, sedimentation of the charge generating substances due to the aggregation, and photosensitive layer It is possible not only to prevent the electrophotographic characteristics from deteriorating due to the roughening of the surface and also to the change in the crystal form of the charge generating substance, but also to form various types of photosensitive layers as described above. Control of electrophotographic characteristics is also possible.

The charge transport layer can be formed by dissolving a charge transport material in a binder resin having a film forming property.
Examples of the organic charge transport material used in the present invention include:
Examples include hydrazone-based compounds, stilbene-based compounds, pyrazoline-based compounds, oxazole-based compounds, thiazole-based compounds, and triarylmethane-based compounds. These charge transport materials can be used alone or in combination of two or more.

Examples of the binder resin used for the charge transport layer include phenoxy resin, polyacrylamide, polyvinyl butyral, polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, and phenol. Resins, epoxy resins, polyesters, alkyd resins, polycarbonates, polyurethanes or copolymers containing two or more of these resin's repeating units, such as styrene-butadiene copolymer, styrene-acrylonitrile polymer, styrene-maleic acid copolymer Can be mentioned. In addition, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene can be selected.

The content of the resin in the charge transport layer is preferably 90% by weight or less, particularly preferably 60% or less, based on the total weight of the charge transport layer.

The thickness of the charge transport layer is preferably from 5 to 40 μm, particularly preferably from 10 to 30 μm.

In the present invention, in order to protect the photosensitive layer from various mechanical and electrical external forces, a so-called protective layer such as a resin layer or a resin layer containing a conductive substance can be provided on the photosensitive layer. .

Further, in the present invention, a layer having a barrier function, a so-called undercoat layer, can be provided between the conductive support and the photosensitive layer.

These various layers are formed by a dip coating method,
It can be formed by a spinner coating method, a Meyer bar coating method, a spray coating method, a blade coating method, or the like.

As the conductive support, those having conductivity itself, for example, aluminum, aluminum alloy, stainless steel, chromium, titanium and the like can be used. In addition, aluminum, aluminum alloy, indium oxide-tin oxide The conductive support or plastic having a layer formed by vacuum deposition of an alloy or the like,
A support in which conductive particles (for example, carbon black, tin oxide particles and the like) are impregnated in a plastic or paper together with a suitable binder, a plastic having a conductive binder, or the like can be used.

[0062]

The present invention will be described below with reference to examples.

Example 1 Conductive powder 1 coated with tin oxide containing 10% of antimony oxide to 75% by weight of titanium oxide
00 parts (parts by weight, hereinafter the same) are added to a solution consisting of 100 parts of a resole phenolic resin (trade name: Plyofen J-325, manufactured by Dainippon Ink Co., Ltd.), 30 parts of methanol, and 100 parts of methylcellosolve, and then ball milled. It was well dispersed in an apparatus to obtain a conductive undercoat paint.

This paint was applied to an aluminum cylinder (80
(φ × 360 mm) by dip coating, and heat-cured at 140 ° C. for 30 minutes to form a 20 μm conductive undercoat layer.

On top of this, 1 part of a polyamide resin (trade name: Amilan CM-8000, manufactured by Toray Industries, Inc.) and 3 parts of 8-nylon resin (trade name: Toresin EF-30T, manufactured by Teikoku Chemical Industry) are mixed with 50 parts of methanol. Then, a coating solution dissolved in a solvent consisting of 40 parts of butanol was applied by dip coating to form an undercoat layer having a thickness of 0.5 μm.

Next, 2.5 parts of the disazo pigment of Exemplified Compound (1) -2 was added to a polyvinyl butyral resin (trade name:
(Esrec BL-S, manufactured by Sekisui Chemical Co., Ltd.) 1.0 part of cyclohexanone dissolved in 70 parts of a solution, and dispersed for 2 hours in a sand mill using 1φ glass beads, diluted with 300 parts of cyclohexanone and 300 parts of methyl ethyl ketone, Prepare as a paint for spray application (paint for charge generation layer (1)).

Similarly, 2.5 parts of the trisazo pigment of (2) -1 was mixed with a solution of 1.0 part of polyvinyl butyral resin in 70 parts of cyclohexanone, and dispersed for 2 hours in a sand mill using 1φ glass beads. The liquid is diluted with 300 parts of cyclohexanone and 300 parts of methyl ethyl ketone to prepare a coating for spray application (coating for charge generation layer (2)).

The paints (1) and (2) were applied onto the undercoat layer by the spray coating device shown in FIG.
Apply in the order of (1), and after drying, paint (1)
mg / m ² , and the paint (2) was applied so as to be 60 mg / m ² (total applied amount / 180 mg / m ² ) to form a laminated charge generation layer.

On the charge generation layer thus obtained, 10 parts of a bisphenol Z-type polycarbonate resin (number average molecular weight 22,000) and polytetrafluoroethylene powder (trade name: Lubron L-2) as a fluorine-containing resin powder (Manufactured by Daikin Industries, Ltd.) together with 40 parts of monochlorobenzene and 15 parts of tetrahydrofuran in a stainless steel ball mill for 50 hours.

[0070]

Embedded image A solution obtained by dissolving 10 parts of a stilbene compound having a structure represented by the following formula was dip-coated and dried with hot air at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 26 μm.

The thus prepared electrophotographic photosensitive member was mounted on a laser beam-equipped PPC (NP-483, manufactured by Canon Inc.).
5), the dark part potential (V _d ) was set to −650 V, the light part potential (V _l ) when irradiating white light, the light part potential (V _bl ) when irradiating laser light, and light Memory for fatigue (photo memory) and rest memory were measured. In addition, _Vl is the amount of light 1.5 lux · sec, V
_bl is a laser beam of 802 nm, output power is 8.0 mW, and a photo memory is a part of the drum which is a white light of 1500 lux.
Difference V _d with irradiated, the irradiation portion and the non-irradiated portion minutes (= [Delta] V
_d ).

[0072] Further, pause memory 10,000 image formations after the photoreceptor was left for 10 hours, V _d of the part and the other parts of the corona charger photoreceptors has become below the while standing
Was evaluated by the difference (ΔV _d ′). ΔV _d and ΔV _d ′
Both when the negative value indicates that the absolute value of V _d is reduced, it is preferable absolute value of [Delta] V _d and [Delta] V _d 'is smaller.

Table 1 shows the results.

Examples 2 to 7 Electrophotographic photosensitive members were prepared in the same manner as in Example 1 except that the compounds shown in Table 1 were used instead of the exemplified compounds (1) -2 and (2) -1. evaluated.

Table 1 shows the results.

Comparative Examples 1-4 The following compounds were used in place of the exemplified compounds (1) -2 and (2) -1 Comparative compound 1

[0077]

Embedded image Comparative compound 2

[0078]

Embedded image Comparative compound 3

[0079]

Embedded image Comparative compound 4

[0080]

Embedded image A photoconductor was prepared in the same manner as in Example 1 except that
evaluated.

Table 1 shows the results.

Incidentally, b is a compound having better sensitivity on the long wavelength side than compound 9. A photoreceptor was prepared and evaluated in the same manner as in Example 1 except for using.

Table 1 shows the results.

Incidentally, b is a compound having better sensitivity on the long wavelength side than compound 9.

COMPARATIVE EXAMPLE 5 Using a paint prepared by previously mixing the charge generating layer paints (1) and (2) at a ratio of 2: 1 by weight, the coating amount after drying was 180
A photoreceptor was prepared and evaluated in exactly the same manner as in Example 1 except that the charge generation layer was provided so as to be mg / m ² .

Table 1 shows the results.

Comparative Example 6 The charge generation layer coating material (2) was applied by a dip coating method, dried to form a 0.1 μm charge generation layer, and then the charge generation layer coating material (1) was immersed thereon. A photoreceptor was prepared and evaluated in the same manner as in Example 1, except that a 0.1 μm charge generation layer was laminated by coating and drying by a coating method.

Table 1 shows the results.

[0089]

[Table 1] Example 8 A solution prepared by dissolving 10 parts of a bisphenol Z-type polycarbonate resin (number average molecular weight 22,000) and 10 parts of the stilbene compound shown in Example 1 in 60 parts of monochlorobenzene was treated with a Meyer bar using a Meyer bar to obtain a 50 μm-thick aluminum plate. The composition was applied on a sheet and dried with hot air at 120 ° C. for 1 hour to form a 20 μm-thick charge transport layer.

Next, the paints (1) and (2) for the charge generation layer shown in Example 1 were applied onto the charge transport layer in the order of the paints (2) and (1) by the spray coater shown in FIG. And apply
After drying the paint by weight (1) is 180 mg / m ^2, coating composition (2) was the 90 mg / m ² is deposited (total coating amount 270m
g / m ² ) A laminated charge generation layer was formed.

The electrophotographic characteristics of the photoreceptor thus prepared were first charged to a surface potential of +700 V using a paper analyzer SP-428 (manufactured by Kawaguchi Electric Works), and then irradiated with light of 5 lux from a halogen lamp light source. Was performed, and the time when the surface potential became +200 V was measured, and the sensitivity was evaluated.

Further, a light of 10 mW / m ² scattered at 780 nm by an interference filter was irradiated, and the light energy required to attenuate the surface potential from +700 V to +200 V was measured to evaluate the sensitivity.

Table 2 shows the results. Comparative Example 7 The coating amount after drying was 270 m using a coating material in which the coating materials for charge generation layer (1) and (2) were previously mixed in a ratio of 2: 1 by weight.
A photoreceptor was prepared and evaluated in exactly the same manner as in Example 8, except that the charge generation layer was provided so as to obtain g / m ² .

Table 2 shows the results.

[0095]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a coating apparatus for producing the electrophotographic photoreceptor of the present invention.

FIG. 2 is a coating apparatus for manufacturing the electrophotographic photosensitive member of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-293360 (JP, A) JP-A-2-205856 (JP, A) JP-A 1-262551 (JP, A) JP-A 64-64 82041 (JP, A) JP-A-2-226257 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5/05 102 G03G 5/06 342 G03G 5/06 360

Claims (4)

(57) [Claims] 1. A conductive support having at least the following formula (1): (Wherein, Ar ₁ is a hydrocarbon aromatic ring which may have a substituent, a heteroaromatic ring which may have a substituent, or the aromatic ring is directly or an aromatic group or a non-aromatic group. represents a divalent group derived from the union with a group, R ₁ and R
₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group. And a compound represented by the following formula (2): (In the formula, Ar ₂ represents a hydrocarbon aromatic ring which may have a substituent, a heteroaromatic ring which may have a substituent, or an aromatic group which is directly or aromatic or non-aromatic. And R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group. And the photosensitive layer is a layer formed by spray-coating the compound represented by the formula (1) and the compound represented by the formula (2) by different spraying devices. An electrophotographic photoreceptor, characterized in that: 2. The electrophotographic photoreceptor according to claim 1, wherein said photosensitive layer has a charge generation layer and a charge transport layer. 3. The following formula (1): (Wherein, Ar ₁ is a hydrocarbon aromatic ring which may have a substituent, a heteroaromatic ring which may have a substituent, or the aromatic ring is directly or an aromatic group or a non-aromatic group. represents a divalent group derived from the union with a group, R ₁ and R
₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group. And a compound represented by the following formula (2): (In the formula, Ar ₂ represents a hydrocarbon aromatic ring which may have a substituent, a heteroaromatic ring which may have a substituent, or an aromatic group which is directly or aromatic or non-aromatic. And R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group. Is spray-coated on a conductive support by a different spray device, and a photosensitive layer containing the compounds represented by the formulas (1) and (2) is formed on the conductive support,
A method for producing an electrophotographic photosensitive member, comprising obtaining an electrophotographic photosensitive member having the photosensitive layer on the conductive support. 4. The method according to claim 3, wherein the photosensitive layer has a charge generation layer and a charge transport layer.