JP3230175B2 - Electrophotographic photoreceptor - 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 photoreceptor, and more particularly to a high-sensitivity photoreceptor effective for a printer, a copying machine, and the like.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor, an inorganic photoreceptor provided with a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, cadmium sulfide and the like has been widely used. However, such an inorganic photoreceptor is required for photosensitivity, heat stability,
The properties such as moisture resistance and durability are not always satisfactory, and the electrophotographic photoreceptor made of selenium or cadmium sulfide has a drawback that the production and handling are greatly restricted in terms of toxicity.

In order to improve such disadvantages of the inorganic photoconductive material, electrophotographic photoreceptors using various organic photoconductive materials have been developed in recent years. In particular, a function-separated type electrophotographic photoreceptor in which a carrier generation function and a carrier transport function are individually assigned to different substances is advantageous for high performance because a suitable substance can be selected in a wide range,
It occupies the mainstream of organic photoreceptors currently in practical use.

Various organic compounds have been proposed as a carrier-generating substance and a carrier-transporting substance for such a function-separated type electrophotographic photoreceptor. As the carrier-generating substance, a polycyclic quinone represented by dibromoanthranthrone has been proposed. Photoconductive substances such as compounds, pyrylium compounds and eutectic complexes of pyrylium compounds, squarium compounds, phthalocyanine compounds and azo compounds have been put to practical use. Further, as a carrier transporting substance, for example, a pyrazoline compound, a polyarylalkane compound, a triphenylamine compound, a hydrazone compound, a diaminobiphenyl compound, a styrylbenzene compound and the like have been put to practical use.

Among the imidazole perylene compounds of the formula [B], which constitute a component of the present invention, Japanese Patent Publication No. 61-8423 (US Pat. No. 3,972,717) discloses a technique used as a carrier-generating substance for an electrophotographic photosensitive member. After that, examples in which the carrier generating material and various carrier transporting materials are combined have been reported. The asymmetric perylene compounds of the formula [A] are also disclosed in JP-A-62-254267 (US Pat. No. 4,714,666) and JP-A-5-6014 (US Pat. No. 5,019,473).
No.) discloses a technique used as a carrier-generating substance. As described above, it is known that each of these carrier generating substances is useful. However, in recent years, there has been an increasing demand for higher sensitivity of electrophotographic photoreceptors. It is no longer enough.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having excellent sensitivity characteristics and stable quality in production.

In response to the demand for higher sensitivity of the electrophotographic photoreceptor, the present inventors have studied the carrier generating substances [A] and [B]. As a result, these substances are mixed more than when each is used alone. It was found that when used as such, an unexpected sensitizing effect occurred and the sensitivity characteristics were significantly improved.

The effect of mixing the carrier-generating substances [A] and [B] was found in addition to sensitization. In general, when a photosensitive layer is formed using a carrier-generating substance, a method of applying the carrier-generating substance by dispersing fine particles in an appropriate dispersion medium,
Alternatively, a vacuum deposition method is used. The vacuum deposition method has a problem that the carrier generation function cannot be sufficiently brought out because the crystal state cannot be controlled, and there is a problem that the cost is low due to low productivity. There are many. However, in the method of dispersion coating, there is a problem that the dispersion state changes during storage of the dispersion and the characteristics of the coated photoreceptor deteriorate.
In this regard, when the carrier-generating substances [A] and [B] are mixed, the storage stability of the dispersion is improved, and even if a photoreceptor is prepared using the dispersion after long-term storage, the characteristics of the photoreceptor No degradation was found to occur.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic device comprising a perylene compound represented by the formula [A] and a perylene compound represented by the formula [B] as a carrier-generating substance. This can be achieved by using a photoreceptor.

That is, the object can be achieved by adopting any of the following configurations.

(1) An electrophotographic photoreceptor comprising an asymmetric perylene compound represented by the formula [A] and an imidazole perylene compound represented by the formula [B] as carrier-generating substances.

[0012]

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[In the formula, Z represents a substituted or unsubstituted divalent aromatic hydrocarbon group or heterocyclic group, R represents a hydrogen atom,
Alkyl group, an aralkyl group, a hydroxyalkyl group, an alkoxyalkyl group, substituted and unsubstituted aromatic hydrocarbon group or a heterocyclic group and table, be assumed except phenethyl
You . ]

[0014]

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(2) (1) wherein the weight ratio A / B of the asymmetric perylene compound represented by the formula [A] to the imidazole perylene compound represented by the formula [B] is A / B ≦ 40/60.
2. The electrophotographic photoreceptor of claim 1.

(3) (1) wherein the weight ratio A / B of the asymmetric perylene compound represented by the formula [A] to the imidazole perylene compound represented by the formula [B] is A / B ≧ 20/80.
2. The electrophotographic photoreceptor of claim 1.

(4) (1) where the weight ratio A / B of the asymmetric perylene compound represented by the formula [A] to the imidazole perylene compound represented by the formula [B] is A / B ≦ 10/90.
2. The electrophotographic photoreceptor of claim 1.

(5) The electrophotographic photosensitive member according to claim 1, wherein the asymmetric perylene compound represented by the formula [A] is a compound represented by the general formula [A '].

[0019]

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[0020] wherein, R 'is a hydrogen atom, an alkyl group, an aralkyl group and the table, it is assumed that except phenethyl group. ]
(6) The electrophotographic photoreceptor according to (4), wherein the asymmetric perylene compound represented by the formula [A] is a compound of the formula [A-1].

[0021]

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(7) (4) wherein the asymmetric perylene compound represented by the formula [A] is a compound of the formula [A-2]
2. The electrophotographic photoreceptor of claim 1.

[0023]

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In the formula [A], preferred examples of Z include:
Examples include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyridine ring, a pyrimidine ring, and an anthraquinone ring. Particularly preferred are a benzene ring and a naphthalene ring, and most preferred is a benzene ring. Z
The above substituents include alkyl, alkoxy, aryl, aryloxy, acyl, acyloxy, amino, carbamoyl, halogen, nitro, cyano and the like. R is a hydrogen atom or a group having 1 to 6 carbon atoms.
And an alkyl group and an aralkyl group are preferred.

In the electrophotographic system, an image is exposed on the surface of a uniformly charged photoreceptor, and an electrostatic latent image is formed by lowering the surface potential of the exposed portion. At that time, the sensitivity of the electrophotographic photoreceptor is determined by the exposure amount necessary to lower the surface potential. By the way, it is the carrier-generating substance that directly converts incident light into charge carriers in the photoreceptor, but since the carrier-generating substance has a unique spectral absorption characteristic, the spectral characteristic of the exposure light source and The sensitivity of the photoreceptor greatly depends on the compatibility of the photoreceptor. Therefore, monochromatic light exposure is performed for absolute comparison of the sensitivity characteristics of the electrophotographic photosensitive member without depending on the type of the light source. In the present invention, the asymmetric perylene compound represented by the formula [A] and the imidazole perylene compound represented by the formula [B] have slightly different spectral absorption wavelength ranges, but both have almost the maximum with respect to light having a wavelength of 520 nm. The sensitivity characteristics of both substances can be directly compared by using 520 nm monochromatic light as the light source. When the sensitivity characteristics of both substances are measured in this way, it is surprisingly found that when both are used in combination, a remarkable sensitizing effect was not obtained when each was used alone. Such a sensitizing effect can be obtained by mixing at any ratio. This point will be clarified based on experimental facts in examples described later.

On the other hand, the asymmetric perylene compound of the formula [A] has photosensitivity mainly in the wavelength range of 450 to 630 nm, whereas the imidazole perylene compound of the formula [B] has a longer wavelength range of 480 to 760 nm. Mainly has photosensitivity.
Due to such a difference in spectral sensitivity range between both compounds,
The appearance of the sensitizing effect of the high-sensitivity photoreceptor produced by mixing the two depends on the exposure light source of the image forming apparatus using the same.

For example, in an image forming apparatus using a panchromatic white light source, a wide spectral sensitivity range of the imidazole perylene compound of the formula [B] is advantageous, so that an asymmetric perylene compound [A] and an imidazole perylene compound [B] are used. When the ratio A / B increases, the effect of the mixed sensitization apparently becomes insufficient. In order to obtain a sufficient mixing sensitizing effect with respect to a white light source, it is desirable that A / B ≦ 40/60.

On the other hand, in an office document copier, in order to faithfully copy a red original, it is usual to filter out light having a wavelength of 620 nm or more in a red light region of an exposure light source. For such a red light cut light source, the spectral sensitivity range extended to the long wavelength side of the imidazole perylene compound [B] loses its effectiveness, and the spectral sensitivity range is shortened to the shorter wavelength side than the imidazole perylene compound [B]. An asymmetric perylene compound [A] having increased sensitivity is advantageous.
For this reason, the ratio A / B of the asymmetric perylene compound [A] to the imidazole perylene compound [B] is opposite to that of the image forming apparatus using the white light source for the red light cut light source.
Is small, the effect of mixing sensitization apparently becomes insufficient. In order to obtain a sufficient mixing sensitizing effect with respect to a red light cut light source, it is desirable that A / B ≧ 20/80.

As described above, in actually utilizing the remarkable sensitizing effect of the present invention, it is desirable to select an optimum mixing ratio region according to the exposure light source. Laser, LED,
For other light sources with a narrow spectral width, high sensitivity can be obtained at an arbitrary mixing ratio, but for a white light source, A /
It is desirable that the range of B ≦ 40/60 is desirable, and it is desirable that the range of A / B ≧ 20/80 is desirable for the light source for red light cut.

In the present invention, the effect of using a mixture of the asymmetric perylene compound of the formula [A] and the imidazole perylene compound of the formula [B] can be obtained by dispersing a carrier-generating substance in a dispersion medium in addition to the above-described sensitizing effect. It also appears as an effect of improving the storage stability of the dispersion coating solution when producing a photoreceptor. In general, the dispersion of the carrier-generating substance changes during storage and the properties of the coated photoreceptor deteriorate, but the mixing of the carrier-generating substances [A] and [B] has a dispersion-stabilizing effect, Even when a photoreceptor is manufactured using the dispersion liquid, the characteristics of the photoreceptor hardly deteriorate. For this reason, it is possible to always provide an electrophotographic photosensitive member having stable quality. Such a dispersion stabilizing effect is achieved by the imidazole perylene compound [B].
This is remarkable when an asymmetric perylene compound [A] is added to a system containing as a main component, and particularly excellent effects can be obtained when A / B ≦ 10/90. Further, when the asymmetric perylene compound is a compound of the formula [A-1] or [A-2], the most excellent effect is obtained.

In the present invention, the perylene compound represented by the formula [A] is easily synthesized according to the reaction formula (1).

[0032]

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The compound represented by the formula [B] is
It is easily synthesized according to the reaction formula (2).

[0034]

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In the above reaction, the compound of the formula [B] is ci
It is obtained as a mixture of the s-isomer and the trans-isomer. These may be used as a mixture alone, or may be isolated and used independently.

Specific examples of the compound represented by the formula [A] are shown below. Z and R represent Z and R in the formula [A].

[0037]

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[0038]

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In the present invention, there may be several methods for incorporating the perylene compound represented by the formula [A] and the perylene compound represented by the formula [B]. For example, the respective compounds are mixed in a solid state at the time of preparing a coating solution. Alternatively, a mixed crystal may be formed after each compound is once made into a uniform dissolved state by an acid pasting treatment or the like.

In the present invention, other carrier-generating substances may be used in addition to the above compounds. Examples of such a carrier generating substance include a phthalocyanine pigment, an azo pigment, an anthraquinone pigment, a perylene pigment, a polycyclic quinone pigment, and a squarium pigment.

As the carrier transporting substance in the photoreceptor of the present invention, various substances can be used. Typical examples thereof include a nitrogen-containing heterocyclic nucleus represented by oxazole, oxadiazole, thiazole, imidazole and the like. And a compound having a fused ring nucleus thereof, a polyarylalkane compound, a pyrazoline compound, a hydrazone compound,
Examples include triarylamine compounds, styryl compounds, styryltriphenylamine compounds, β-phenylstyryltriphenylamine compounds, butadiene compounds, hexatriene compounds, carbazole compounds, condensed polycyclic compounds, and the like. Specific examples of these carrier transporting substances include, for example, the carrier transporting substances described in JP-A-61-107356, and particularly typical structures are shown below.

[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

Various configurations of the photoreceptor are known. The photoreceptor of the present invention can take any of these forms,
It is desirable to use a laminated type or a dispersed type function-separated type photoconductor. In this case, the configuration is usually as shown in FIGS. In the layer configuration shown in FIG. 2A, a carrier generation layer 2 is formed on a conductive support 1 and a carrier transport layer 3 is formed on the carrier generation layer 2.
Are laminated to form a photosensitive layer 4, and (b) shows a photosensitive layer 4 'in which the carrier generation layer 2 and the carrier transport layer 3 are reversed. (C) provides an intermediate layer 5 between the photosensitive layer 4 having the layer configuration of (a) and the conductive support 1, and (d) shows the photosensitive layer 4 'having the layer configuration of (b) and the conductive support 1. And an intermediate layer 5 is provided between them. The layer configuration of (e) is obtained by forming a photosensitive layer 4 ″ containing a carrier generating substance 6 and a carrier transporting substance 7, and (f) is a section between such a photosensitive layer 4 ″ and the conductive support 1. Middle layer 5
With

In the formation of the photosensitive layer, the carrier generating layer may be formed by coating a carrier generating substance alone or a liquid in which fine particles are dispersed in an appropriate dispersion medium together with a binder or an additive, or by vacuum deposition of the carrier generating substance. Is valid. In the former case, as the dispersing means, a dispersing device such as an ultrasonic dispersing machine, a ball mill, a sand mill, and a homomixer can be used. For the carrier transport layer, it is effective to apply a solution in which the carrier transport material is dissolved alone or together with a binder or an additive.

When a binder is used for forming the carrier generation layer or the carrier transport layer, any binder can be selected, but a high molecular polymer which is particularly hydrophobic and has a film forming ability is desirable. Examples of such a polymer include the following,
It is not limited to these.

Polycarbonate Polycarbonate Z resin Acrylic resin Methacrylic resin Polyvinyl chloride Polyvinylidene chloride Polystyrene Styrene-butadiene copolymer Polyvinyl acetate Polyvinyl formal Polyvinyl butyral Polyvinyl acetal Polyvinyl carbazole Styrene alkyd resin Silicone resin Silicone alkyd resin Polyester Phenol resin Polyurethane Epoxy Resin Vinylidene chloride-acrylonitrile copolymer Vinyl chloride-vinyl acetate copolymer Vinyl chloride-vinyl acetate-maleic anhydride copolymer The ratio of the carrier-generating substance to the binder is as follows:
10 to 600 parts by weight of the carrier generating substance is desirable for 100 parts by weight, and more preferably 50 to 500 parts by weight. The ratio of the carrier transporting substance to the binder is preferably 10 to 500 parts by weight based on 100 parts by weight of the binder. The thickness of the carrier generation layer is set to 0.01 to 20 μm, preferably 0.05 to 5 μm. The thickness of the carrier transport layer is from 1 to 100 μm, preferably from 5 to 50 μm.

As the binder used for the intermediate layer, the protective layer and the like, those mentioned above for the carrier generating layer and the carrier transporting layer can be used. In addition, polyamide resin, nylon resin, ethylene-vinyl acetate, etc. Polymers, ethylene resins such as ethylene-vinyl acetate maleic anhydride copolymer, ethylene-vinyl acetate methacrylic acid copolymer, polyvinyl alcohol, cellulose derivatives and the like are effective. Further, a curable binder utilizing thermal curing or chemical curing of melamine, epoxy, isocyanate, or the like can also be used.

As the conductive support, a metal plate or a metal drum is used, and a thin layer of a conductive compound such as a conductive polymer or indium oxide, or a metal such as aluminum or palladium is applied, vapor-deposited or laminated. What is provided on a substrate such as paper or a plastic film by means can be used.

The photoreceptor of the present invention has the above-mentioned structure, and is excellent in sensitivity characteristics and quality stability, as is apparent from the following examples.

[0055]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

Synthesis Example 1 3.9 g of perylene-3,4,9,10-tetracarboxylic dianhydride, n
5.3 g of -propylamine and 100 ml of water were mixed and stirred at 50 ° C for 3 hours. After the reaction, the precipitate was filtered out with hydrochloric acid and washed with water, then dissolved in a 1% aqueous potassium hydroxide solution, and filtered by heating to remove alkali-insoluble substances. Potassium chloride was added to the filtrate to a concentration of 10%, and the deposited precipitate was collected by filtration to remove dissolved unreacted raw materials. The resulting precipitate is purified by dissolving it in 1% potassium hydroxide, adding potassium chloride and salting out repeatedly, and finally adding hydrochloric acid to precipitate, washing with water and drying, and perylene-3,4,9,10-tetratetrahydrofuran. 3.0 g of carboxylic acid monoanhydride-monopropylimide were obtained. This was mixed with 1.1 g of o-phenylenediamine and 50 ml of α-chloronaphthalene, and heated under reflux for 3 hours. The precipitated crystals are collected by filtration,
A methanol wash was performed. This was dried and purified by sublimation to obtain 3.0 g of Exemplified Compound A-4.

Synthesis Example 2 3.9 g of perylene-3,4,9,10-tetracarboxylic dianhydride, o
-2.7 g of phenylenediamine, 100 m of α-chloronaphthalene
were mixed and heated to reflux for 4 hours. The precipitated crystals were collected by filtration and washed with methanol. After drying, it is purified by sublimation, and the cis form of the perylene compound represented by the formula [B], trans
4.2 g of a body mixture were obtained.

Example 1 Exemplified Compound A-4; 0.001 parts by weight, a compound of the formula [B]; 0.99
9 parts by weight, 0.2 parts by weight of polyvinyl butyral "Eslec BL-1" (manufactured by Sekisui Chemical Co., Ltd.) as a binder resin,
Using a sand mill, 40 parts by weight of methyl ethyl ketone was dispersed as a dispersion medium using a sand mill, and the resulting dispersion was applied on a polyester film on which aluminum had been deposited using a wire bar.
A 6 μm carrier generation layer was formed. On top of that, 1 part by weight of a carrier transporting substance T-2, 1.3 parts by weight of a polycarbonate resin "Iupilon Z200" (manufactured by Mitsubishi Gas Chemical Company), and a small amount of silicone oil "KF-54" (manufactured by Shin-Etsu Chemical Co., Ltd.). Then, a solution dissolved in 10 parts by weight of 1,2-dichloroethane was applied using a blade coater, dried, and then a carrier transport layer having a thickness of 25 μm was formed. The photoreceptor thus obtained is referred to as Sample 1.

Examples 2 to 8 In the same manner as in Example 1 except that the compound A-4 and the compound of the formula [B] were used in the weight ratio shown in Table 1 (1 part by weight in total) in Example 1, A photoreceptor was produced. These are referred to as samples 2 to 8, respectively.

Comparative Example 1 A photoconductor was prepared by the same way as that of Example 1 except that 1 part by weight of compound of formula [B] was used without using compound A-4. This is designated as Comparative Sample 1.

Comparative Example 2 The compound of Example A was prepared without using the compound of the formula [B] in Example 1.
4: A photoconductor was prepared in the same manner as in Example 1, except that 1 part by weight was used. This is designated as Comparative Sample 2.

(Evaluation 1) —Measurement of Monochromatic Light Sensitivity— The photoreceptor obtained as described above was measured for monochromatic light sensitivity using a paper analyzer EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.) as follows. did. First, after performing corona charging at −6 kV, irradiation with monochromatic light having a wavelength of 520 nm and a light intensity of 0.1 μW / cm ² is performed, and the exposure energy E1 / 2 required for lowering the surface potential from −800 V to −400 V is obtained. I asked. The results are shown in Table 1.

[0063]

[Table 1]

Examples 9 to 12 In Example 1, A was used instead of the carrier-generating substance A-4.
A photoconductor was prepared by the same way as that of Example 1 except that, using A-6 and A-23, the mixing ratio was changed to the weight ratio shown in Table 2 (1 part by weight in total). These are referred to as samples 9 to 12, respectively.

Comparative Examples 3 and 4 In Example 1, the compound A was used without using the compound of the formula [B].
-6 and A-23 were prepared in the same manner as in Example 1, except that 1 part by weight of A-23 was used alone. These are referred to as comparative samples 3 and 4, respectively.

Comparative Examples 5 to 6 In Example 1, the following compounds G-1 and B, and A-6 and G-1 were used in the weight ratios shown in Table 2 in place of the carrier-generating substances A-4 and B. In the same manner as in Example 1, a photoconductor was produced. These are referred to as Comparative Samples 5 and 6, respectively.

[0067]

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(Evaluation) The photoreceptor thus obtained was measured for monochromatic light sensitivity in the same manner as in Evaluation 1.

Table 2 shows the results.

[0070]

[Table 2]

As is evident from the above examples, the compound of the imidazole perylene formula [B] or the asymmetric perylene compound [A] is significantly sensitized when used in combination as compared with when used alone. The effect is obtained.

Example 13 0.05 parts by weight of the compound A-8 and 0.95 parts by weight of the compound of the formula [B] were put into a molybdenum sublimation boat and the degree of vacuum was 10 ^-5 torr.
r, vacuum deposition was performed at a deposition source temperature of 400 ° C. to form a carrier generation layer having a thickness of 0.3 μm. Next, a carrier transport layer was formed in the same manner as in Example 1 to produce a photoconductor. When the monochromatic light sensitivity of this sample was measured according to Evaluation 1, E
_1/2 was 2.27 (erg / cm ² ).

Comparative Example 7 The compound A of Example 13 was used without using the compound of the formula [B].
A photoconductor was prepared in the same manner as in Example 13, except that vacuum deposition was performed using -8 alone, and the monochromatic light sensitivity was measured according to Evaluation 1 to find that E _1/2 was 2.40 (erg / cm ² ). .

(Evaluation 2) -Measurement of White Light Sensitivity- The samples obtained in Examples 1 to 8 and Comparative Examples 1 and 2
White light sensitivity was measured as follows using a paper analyzer EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.). First, -6kV
After performing corona charging, exposure was performed using a halogen lamp so that the illuminance on the sample surface was 2 lux, and the exposure amount E600 / 100 required to reduce the surface potential from −600 V to −100 V was determined. Was. The results are shown in Table 3.

[0075]

[Table 3]

As described above, the weight ratio of the asymmetric perylene compound to the compound of the formula [B] is particularly limited to A /
When B ≦ 40/60, it appears as a sensitivity effect that is superior to that of each compound alone.

(Evaluation 3) -Measurement of Red Light Cut Sensitivity- The samples obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were also exposed through a filter that cuts light having a wavelength of 620 nm or more in Evaluation 2. Other than the above, the measurement was carried out in the same manner as in Evaluation 2, and the exposure amount EC600 / 100 required to lower the surface potential from −600 V to −100 V was determined. The results are shown in Table 4.

[0078]

[Table 4]

As described above, when the weight ratio of the asymmetric perylene compound to the compound of the formula [B] is A / B ≧ 20/80, the sensitivity effect is higher than that of the respective compounds alone, especially for the red light cut light source. Appear as.

Examples 14 to 18 The exemplified compound A-1 and the compound of the formula [B] were used in a weight ratio shown in Table 5 (1 part by weight in total), and polycarbonate "PANLITE L1250" (Teijin Chemical Co., Ltd.) was used as a binder resin. Made)
The mixture was dispersed using a sand mill together with 0.3 parts by weight and 50 parts by weight of 1,2-dichloroethane as a dispersion medium to obtain a dispersion for coating a carrier generation layer. This was applied on a polyester film on which aluminum had been deposited by using a wire bar to form a carrier generation layer having a thickness of 0.4 μm. On top of that, 1 part by weight of a carrier transporting substance T-2, 1.3 parts by weight of a polycarbonate resin "Iupilon Z300" (manufactured by Mitsubishi Gas Chemical Company), and a small amount of a silicone oil "KF-54" (manufactured by Shin-Etsu Chemical Co., Ltd.). A solution dissolved in 10 parts by weight of 1,2-dichloroethane was applied using a blade coater and dried, and then the film thickness was 31 μm.
Was formed to obtain a photoreceptor. This is called an immediate sample. On the other hand, the dispersion for coating the carrier generation layer obtained here was left at 50 ° C. for 5 days as an accelerated test for preservability. Next, a photoconductor was prepared in the same manner as described above except that this dispersion was used. This is called a stored sample.

Comparative Example 8 Compound B was used in Examples 14 to 18 without using compound A-1.
An immediate sample and a preserved sample were obtained in the same manner as in Examples 14 to 18 except that a dispersion was prepared using 1 part by weight.

(Evaluation 4) These samples were evaluated using a paper analyzer EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.) as follows. First, corona charging is performed at -6 kV for 5 seconds, and the surface potential Va immediately after charging and the surface potential Vi after standing for 5 seconds are determined. Subsequently, exposure is performed using a halogen lamp light source so that the surface illuminance becomes 2 lux. Was. DD = 100 (Va
−Vi) / Va to calculate the dark decay rate DD, and set the surface potential to −600.
Exposure E600 / 10 required to reduce V to -100V
The immediate and stored samples were compared for 0.
Table 5 shows the results.

[0083]

[Table 5]

Examples 19-21 Exemplified compounds A-2, A-4, and A-6 were used in place of compound A-1 in Examples 14-18, and the mixing ratios shown in Table 6 were used. Parts by weight), an immediate sample and a preserved sample were prepared in the same manner as in Examples 14 to 18. Next, it evaluated similarly to evaluation 4. Table 6 shows the results.

[0085]

[Table 6]

The above results show that the storage stability of the dispersion is improved when the asymmetric perylene compound is mixed as compared with the case of using the compound of the formula [B] alone, especially when A / B ≦ 10/90. Excellent effects are seen, indicating that sensitivity and chargeability are stabilized.

[0087]

According to the present invention, it can be seen that an electrophotographic photosensitive member having excellent sensitivity characteristics and stable quality can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a specific example of a layer configuration of a photoconductor of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive support 2 carrier generating layer 3 carrier transporting layer 4, 4 ′, 4 ″ photosensitive layer 5 intermediate layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-59671 (JP, A) JP-A-5-6014 (JP, A) JP-A-5-6016 (JP, A) JP-A-62-162 54267 (JP, A) JP-A-4-242260 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/06

Claims (7)

(57) [Claims] 1. An electrophotographic photoreceptor comprising an asymmetric perylene compound represented by the formula [A] and an imidazole perylene compound represented by the formula [B] as a carrier-generating substance. Embedded image [In the formula, Z represents a substituted or unsubstituted divalent aromatic hydrocarbon group or a heterocyclic group, and R represents a hydrogen atom, an alkyl group,
Aralkyl group, a hydroxyalkyl group, an alkoxyalkyl group, substituted and unsubstituted aromatic hydrocarbon group or a heterocyclic group and the table, it is assumed that except phenethyl group. [Chemical formula 2] 2. The method according to claim 1, wherein the weight ratio A / B of the asymmetric perylene compound represented by the formula [A] to the imidazole perylene compound represented by the formula [B] is A / B ≦ 40/60. The electrophotographic photosensitive member according to the above. 3. The method according to claim 1, wherein the weight ratio A / B of the asymmetric perylene compound represented by the formula [A] and the imidazole perylene compound represented by the formula [B] is A / B ≧ 20/80. The electrophotographic photosensitive member according to the above. 4. The method according to claim 1, wherein the weight ratio A / B of the asymmetric perylene compound represented by the formula [A] to the imidazole perylene compound represented by the formula [B] is A / B ≦ 10/90. The electrophotographic photosensitive member according to the above. 5. The electrophotographic photoreceptor according to claim 1, wherein the asymmetric perylene compound represented by the formula [A] is a compound represented by the general formula [A ']. Embedded image Wherein, R 'is <br/> table hydrogen atom, an alkyl group, an aralkyl group, it is assumed that except phenethyl group. ] 6. The electrophotographic photosensitive member according to claim 4, wherein the asymmetric perylene compound represented by the formula [A] is a compound represented by the formula [A-1]. Embedded image 7. The electrophotographic photosensitive member according to claim 4, wherein the asymmetric perylene compound represented by the formula [A] is a compound represented by the formula [A-2]. Embedded image