JPH027458B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to electrophotographic photoreceptors, and more particularly to electrophotographic photoreceptors having a carrier transport layer combined with a layer of material that absorbs light and generates charge carriers. To date, carrier generation layers (hereinafter referred to as ``CGL'') containing a carrier generation substance (hereinafter referred to as ``CGM'') that absorbs visible light and generates charged carriers (hereinafter simply referred to as ``carriers''). )
and a carrier transport layer (hereinafter referred to as "CTL") containing a carrier transport material (hereinafter referred to as "CTM") that transports either or both of the positive and negative carriers generated in this CGL. It has been proposed that a photosensitive layer of an electrophotographic photoreceptor can be constructed by combining these materials. in this way,
By assigning the two basic functions necessary for the photosensitive layer, carrier generation and transport, to separate layers, the range of materials that can be used in the composition of the photosensitive layer is widened, and each function can be optimized. By doing so, it becomes possible to independently select materials or material systems that achieve the desired properties in the electrophotographic process, such as a high surface potential when charged, a large charge retention ability, and a high resistance to light. It becomes possible to construct an electrophotographic photoreceptor having excellent characteristics such as high sensitivity and great stability in repeated use. Conventionally, as such a photosensitive layer, the following ones are known, for example. (1) Consisting of amorphous selenium or cadmium sulfide
A structure in which CGL and CTL made of poly-N-vinylcarbazole are laminated. (2) Consisting of amorphous selenium or cadmium sulfide
A structure in which CGL and CTL containing 2,4,7-trinitro-9-fluorenone are laminated. (3) A structure in which a CGL made of a perylene derivative and a CTL containing an oxadiazole derivative are laminated (see US Pat. No. 3,871,882). (4) A structure in which a CGL made of chlordiane blue or methylscalyllium and a CTL containing a pyrazoline derivative are laminated (Japanese Patent Application Laid-Open No. 1973-
(See Publication No. 90827). (5) CGL made of amorphous selenium or its alloy;
A structure in which CTL containing a polyarylalkane-based aromatic amino compound is laminated (patent application)
52-147251). (6) A structure in which CGL containing a perylene derivative and CTL containing a polyarylalkane-based aromatic amino compound are laminated (Patent application 1973-
19907 specification). As described above, many types of photosensitive layers are known, but in conventional electrophotographic photoreceptors having such photosensitive layers, the photoreceptor is exposed to sunlight or fluorescent light during maintenance, paper jam processing, etc. In this case, the photoreceptor is exposed to sunlight or ultraviolet rays contained in the light of a fluorescent lamp, resulting in deterioration of its characteristics and deterioration of image quality. For this reason, for the purpose of preventing deterioration of characteristics due to ultraviolet rays, for example, Japanese Patent Application Laid-Open No. 56-33652 discloses an electrophotographic photoreceptor containing triarylmethane and benzotriazole.
The publication describes an electrophotographic photoreceptor containing biphenylamine and benzotriazole,
Publication No. 52756 discloses an electrophotographic photoreceptor containing biphenylamine and diarylmethane or triarylmethane, and in these examples, the effect of preventing deterioration of characteristics due to ultraviolet rays can be recognized, but Since the degree is small, there is a drawback that it is not practical. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide an electrophotographic photoreceptor that exhibits little deterioration in characteristics even when irradiated with ultraviolet rays, and therefore has high durability for practical use. The electrophotographic photoreceptor of the present invention is characterized by:
a conductive support; provided on the conductive support;
and a photosensitive layer made of a laminate of CGL and CTL,
The CTL contains a carbazole derivative represented by the following general formula [], and the CTL or
The point is that at least one of the CGLs contains a benzotriazole derivative represented by the following general formula []. General formula [] (In the formula, R ₁ represents a substituted or unsubstituted aryl group, R ₂ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group,
represents an amino group, substituted amino group or hydroxyl group,
R ₃ represents a substituted or unsubstituted aryl group, a substituted or unsubstituted thienyl group, or a substituted or unsubstituted carbazolyl group. ) General formula [] (In the formula, R ₄ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an aryl group, or a nitro group, and R ₅ and R ₆ each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or an aryl group. That is, in the present invention, a carbazole derivative represented by the above general formula [] is used as a CTM to be incorporated into the CTL of the photosensitive layer, and a benzotriazole derivative represented by the above general formula [] is used as an ultraviolet absorber in the CTL. By incorporating it in one or both of CGL and combining it with CGM, it forms a photosensitive layer of a so-called functionally separated photoreceptor in which carrier generation and transport are performed by separate substances. This makes it possible to provide an electrophotographic photoreceptor with high durability against ultraviolet rays. Specific examples of the carbazole derivative represented by the above general formula [] that can be effectively used in the present invention include those having the following structural formula, but are not limited thereto. Structural formula Specific examples of the benzotriazole derivative represented by the above general formula [] that can be effectively used in the present invention include those having the following structural formula, but are not limited thereto. . Structural formula Next, the mechanical structure of the electrophotographic photoreceptor of the present invention will be explained. In one example of the present invention, as shown in FIG. 1, a CGT 2 containing CGM as a main component, which will be described later, is formed on a conductive support 1.
A CTL 3 containing CTM as a main component, which will be described later, is laminated and formed on the CGL 2.
2 and CTL 3 constitute a photosensitive layer 4. Here, as the material of the conductive support 1, for example, a sheet of metal such as aluminum, nickel, copper, zinc, palladium, silver, indium, tin, platinum, gold, stainless steel, or brass can be used. However, the invention is not limited thereto, and for example, as shown in FIG. It has flexibility such as paper, plastic sheet, etc.
In addition, it is appropriate that the material has sufficient strength against stresses such as bending and tension. The conductive layer 1B can also be provided by laminating metal sheets, vacuum depositing metal, or by other methods. The CGL 2 can be formed by CGM alone, which will be described later, by adding a suitable binder resin to it, or by adding a substance having a high mobility toward carriers of specific or non-specific polarity, that is, CTM. can. As a specific method, CGM is placed on the support.
Examples include a method in which CGM is vacuum-deposited, and a method in which CGM is dissolved or dispersed in a suitable solvent and then applied and dried. In this latter method, CGL2 can contain a benzotriazole derivative used as an ultraviolet absorber in the present invention. In this case, the content ratio of the benzotriazole derivative to CGL2 is 0.1 to 20% by weight, especially 1 to 10% by weight.
It is preferable that the UV absorbing effect is increased by doing so,
Deterioration of CGM due to ultraviolet rays can be reliably prevented. When the content of the benzotriazole derivative is less than 0.1% by weight, a sufficient effect of preventing UV deterioration cannot be obtained, and when it exceeds 20% by weight, the sensitivity decreases. In this case, a binder resin or CTM may be added to CGM, and in that case, the ratio of CGM:binder resin:CTM is 1:0 to 100:0 to 500, particularly 1:0 to 500, by weight.
The ratio is preferably 10:0 to 50. As CGM, any inorganic pigment or organic dye can be used as long as it absorbs visible light and generates free carriers. In addition to inorganic pigments such as amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, mercury sulfide, lead oxide, and lead sulfide, the following representative examples Organic dyes such as those shown in may also be used. (1) Azo dyes such as monoazo dyes, polyazo dyes, metal complex azo dyes, pyrazolone azo dyes, stilbene azo dyes, and thiazole azo dyes (2) Perylene dyes such as perylenic anhydride and perylenic acid imide (3) Anthraquinone Anthraquinone or polycyclic quinone dyes such as derivatives, anthorone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives and isoviolanthrone derivatives (4) Indigoid dyes such as indigo derivatives and thioindigo derivatives (5) Metals Phthalocyanine dyes such as phthalocyanine and metal-free phthalocyanine (6) Carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes and acridine dyes (7) Quinoneimine dyes such as azine dyes, oxazine dyes and thiazine dyes (8) Methine dyes such as cyanine dyes and azomethine dyes (9) Quinoline dyes (10) Nitro dyes (11) Nitroso dyes (12) Benzoquinone and naphthoquinone dyes (13) Naphthalimide dyes (14) Bisbenzimidazole derivatives Perinone dyes (15) Quinacridone dyes Among these organic dyes, polycyclic quinone dyes are particularly preferred because they bond well with the carbazole derivative used as CTM in the present invention and provide high sensitivity. Binder resins that can be contained in CGL include, for example, polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, polycarbonate resin,
Addition polymer resins, polyaddition resins, polycondensation resins such as silicone resins and melamine resins, and copolymer resins containing two or more repeating units of these resins, such as vinyl chloride-vinyl acetate copolymers In addition to insulating resins such as polymer resins and vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, poly-N-
Examples include polymeric organic semiconductors such as vinyl carbazole. High mobility for carriers of specific or non-specific polarity that can be added to the CGL
As the CTM, the CTM used in the configuration of CTL 3 and the like in the present invention can be used as a part or whole thereof, but other CTMs may be used in consideration of the performance as an electrophotographic photoreceptor. Furthermore, this CGL can contain one or more Lewis acids for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue during repeated use.
Examples of such Lewis acids include succinic anhydride, maleic anhydride, dibromaleic anhydride,
Phthalic anhydride, tetrachlorophthalic anhydride, tetrapromophthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene , m-dinitrobenzene, 1,3,5-trinitrobenzene, paranitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, bromanil, dichlorodicyanoparabenzoquinone, anthraquinone, dinitroanthraquinone, 2,7-dinitrofluorenone, 2 ,4,7
-Trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 9-fluorenylidene-[dicyanomethylenemalonodinitrile], polynitro-9-fluorenylidene-[dicyanomethylenemalonodinitrile], picric acid, o-nitrobenzoin acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid,
Examples include phthalic acid, mellitic acid, and other compounds with high electron affinity. The thickness of the CGL 2 formed as described above is preferably 0.005 to 20 microns, particularly preferably 0.05 to 5 microns. If it is less than 0.005 microns, sufficient photosensitivity cannot be obtained, and if it exceeds 20 microns, sufficient charge retention cannot be obtained. CTL3 is a method in which a carbazole derivative represented by the above-mentioned general formula [] is used as CTM, and a coating solution obtained by dissolving or dispersing it in an appropriate solvent together with an appropriate binder resin is applied and dried; It can be formed by other methods. Examples of binder resins that can be contained in CTL in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, and polycarbonate. Addition polymer resins such as resins, silicone resins, and melamine resins, polyaddition resins, polycondensation resins, and copolymer resins containing two or more repeating units of these resins, such as vinyl chloride-vinyl acetate copolymer resins. Examples include insulating resins such as polymer resins and vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, as well as polymeric organic semiconductors such as poly-N-vinylcarbazole. This CTL3 can contain a benzotriazole derivative used as an ultraviolet absorber in the present invention. In this case, the content ratio of the benzotriazole derivative to the carbazole derivative in CTL3 is 0.1 to 20% by weight, especially 1
The content is preferably 10% by weight. By doing so, the ultraviolet absorption effect can be increased, and deterioration of CTM due to ultraviolet rays can be reliably prevented. If the content of this benzotriazole derivative is less than 0.1% by weight, a sufficient effect of preventing UV deterioration cannot be obtained, and if it exceeds 20% by weight, sensitivity decreases. In the present invention, the content ratio of the binder resin and carbazole derivative used in CTL is 20 to 20 parts by weight of the carbazole derivative per 100 parts by weight of the binder resin.
The amount is 400 parts by weight, preferably 50 to 200 parts by weight. In the present invention, the CTL can also contain a Lewis acid similar to that described above for the purpose of improving sensitivity, further reducing residual potential, and fatigue during repeated use. In this case, the content ratio is 0.001 to 10 parts by weight of Lewis acid per 100 parts by weight of CTM, preferably
It is 0.01 to 5 parts by weight. If it is less than 0.001 part by weight, the image background potential (white paper potential) will increase significantly;
If the amount exceeds 1 part by weight, the image potential (black paper potential) decreases significantly and stable repeatability cannot be obtained. The thickness of the CTL 3 thus formed is between 2 and 100 microns, preferably between 5 and 30 microns. The present invention has been explained above according to the specific configuration example shown in FIG. 1 or FIG. 2, but in the present invention,
The CTL combined with the CGL may contain a carbazole derivative, and at least one of the CGL or the CTL may contain a benzotriazole derivative, and the mechanical structure of the electrophotographic photoreceptor can be arbitrarily selected. For example, as shown in FIG. 3, a suitable intermediate layer 5 is provided on a conductive support 1, and a CGL2
may be formed, and CTL3 may be formed on this CGL2. This intermediate layer 5 has a function of preventing free carriers from being injected from the conductive support 1 into the photosensitive layer 4 when the photosensitive layer 4 is charged;
Alternatively, it can function as an adhesive layer that integrally adheres the photosensitive layer 4 to the conductive support. Materials for the intermediate layer 5 include metal oxides such as aluminum oxide and indium oxide, acrylic resins, methacrylic resins, vinyl chloride resins, vinyl acetate resins, epoxy resins, polyurethane resins, phenolic resins, polyester resins,
Polymer materials such as alkyd resin, polycarbonate resin, silicone resin, melamine resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, etc. can be used. Further, as shown in FIG. 4, on the conductive support 1,
The photosensitive layer 4 may be constructed by forming the CTL 3 with or without the intermediate layer 5 and forming the CGL 2 on the CTL 3. In the above, it is of course effective to include a benzotriazole derivative in both the CGL2 and CTL3 layers. Since the electrophotographic photoreceptor of the present invention has the above-mentioned configuration, as will be understood from the examples described later, the benzotriazole derivative acts as an ultraviolet absorber, thereby reliably preventing deterioration of CGM and CTM due to ultraviolet rays. and therefore CTM
The properties of the carbazole derivative used as the compound are well exhibited, and excellent electrophotographic properties can be obtained. That is, according to the electrophotographic photoreceptor of the present invention, even if the photoreceptor is irradiated with ultraviolet rays during maintenance, paper jam processing, etc., high-quality images can be stably obtained over a long period of time. It is possible to obtain extremely high durability. Although it is not clear why the electrophotographic photoreceptor of the present invention can stably obtain good properties over a long period of time, it is clear that the ultraviolet absorption spectra of benzotriazole derivatives and carbazole derivatives overlap greatly, and that benzotriazole derivatives It is believed that this is because it does not act as a trapping agent for carriers. Figure 5 shows the carbazole derivative represented by the structural formula [-14] and the structural formula [-6] according to the present invention.
This figure shows the ultraviolet absorption spectra of the benzotriazole derivative represented by the formula and the conventionally used triarylmethane (see Comparative Example 5 below), where the curve f ₁ is represented by the structural formula [-14]. Carbazole derivative, curve f ₂ is structural formula [
-6], the curve _f3 is based on triarylmethane. This figure shows that the ultraviolet absorption spectra of the carbazole derivative represented by the structural formula [-14] and the benzotriazole derivative represented by the structural formula [-6] are in good agreement. It turns out that this can be effectively prevented by adding triazole derivatives. On the other hand, in the case of triarylmethane, the absorption bands overlap with those of the carbazole derivative and the effect of preventing deterioration is small. Examples of the present invention will be described below, but the present invention is not limited thereto. Example 1 A conductive support made of polyethylene terephthalate with a thickness of 100 microns on which aluminum was deposited was coated with a vinyl chloride-vinyl acetate-maleic anhydride copolymer "Eslec MF-10" (manufactured by Sekisui Chemical Co., Ltd.). An intermediate layer with a thickness of about 0.05 microns was ^provided , and 4.10-dibromanthanthrone "Monolite Red 2Y" (CI No. 59300 ICI
evaporated by heating at 350°C for 3 minutes,
This is deposited on the intermediate layer to a thickness of approximately
A 0.5 micron CGL was formed. On the other hand, 11.25 g of a carbazole derivative represented by the structural formula [-24], 0.24 g of a benzotriazole derivative represented by the structural formula [-6], and a polycarbonate resin "Panlite L-1250" (manufactured by Teijin Chemicals)
15g of 1,2-dichloroethane was dissolved in 100ml of 1,2-dichloroethane, and the resulting CTL-forming solution was applied onto the CGL using a doctor blade and dried at a temperature of 80°C for 1 hour to form a CTL with a thickness of 12 microns. death,
An electrophotographic photoreceptor of the present invention was thus prepared. This will be referred to as "Sample 1". Furthermore, 1,2-dichloroethane was added to the CTL forming solution to dilute it 10 times, and the resulting solution was coated onto a quartz glass plate using a spin coating method to a thickness of approximately
A 0.1 micron absorption spectrum measurement sample was prepared. This will be referred to as "measurement sample 1." Example 2 As a benzotriazole derivative, structural formula [-
A CTL having a thickness of 12 microns was formed in the same manner as in Example 1 except that the material shown in item 7) was used, thereby producing an electrophotographic photoreceptor of the present invention. This will be referred to as "Sample 2." Furthermore, a sample for absorption spectrum measurement was prepared in the same manner as in Example 1. This will be referred to as "measurement sample 2." Example 3 A CTL having a thickness of 12 microns was formed in the same manner as in Example 1 except that the carbazole derivative represented by the structural formula [-14] was used, thereby producing an electrophotographic photoreceptor of the present invention. This will be referred to as "Sample 3." Furthermore, a sample for absorption spectrum measurement was prepared in the same manner as in Example 1. This will be referred to as "measurement sample 3." Example 4 A CTL having a thickness of 12 microns was formed using the same CTL forming solution as in Example 1 on a conductive support provided with an intermediate layer similar to that in Example 1. On the other hand, polycarbonate resin “Panlite L-
1250'' (manufactured by Teijin Kasei), 1 g of a carbazole derivative represented by the structural formula [-24], and the structural formula [-
6] was dissolved in 100 ml of 1,2-dichloroethane, and 4,10-dibromanthanthrone was added to the resulting solution.
0.6g was added and subjected to ultrasonic dispersion, and the resulting dispersion was applied onto the CTL to a thickness of 2 microns.
A CGL was formed to produce an electrophotographic photoreceptor of the present invention. This will be referred to as "Sample 4." Comparative Examples 1 to 4 Comparative electrophotographic photoreceptors were prepared in the same manner as in Examples 1 to 4, except that the benzotriazole derivative was not used in each of Examples 1 to 4. These will be referred to as "Comparative Sample 1" to "Comparative Sample 4", respectively. Comparative Example 5 A comparative electrophotographic photoreceptor was produced in the same manner as in Example 1 except that triarylmethane represented by the following structural formula was used in place of the carbazole derivative in Example 1. This will be referred to as "comparative sample 5." Furthermore, samples for absorption spectrum measurement were prepared in the same manner as in Examples 1 to 3. These are respectively referred to as "comparative measurement sample 1" to "comparative measurement sample 3." Samples 1 to 4 and Comparative Samples 1 to 5 according to the above Examples and Comparative Examples were tested using the Electrometer SP-428
The electrophotographic characteristics were measured using a dynamic method. In other words, the surface potential V _A when charged at a charging potential of -6.0kV
(V), the amount of exposure required to attenuate the surface potential V _A from 500 (V) to 50 (V) E ⁵⁰⁰ ₅₀ (lux・sec) and the residual potential after exposure V _R ( V) was measured. Next, in order to examine the stability against ultraviolet rays, each of Samples 1 to 4 and Comparative Samples 1 to 5 was exposed to light for 60 seconds at a distance of 5 cm from an ultra-high pressure mercury lamp "SHL-100UV" (manufactured by Tokyo Shibaura Electric Co., Ltd.). irradiation, and then measurements similar to those described above were performed again. The results are shown in Table 1.

[Table] From the results in Table 1, the characteristics of Samples 1 to 4 according to the present invention hardly changed even after being irradiated with ultraviolet rays, and the initial good characteristics were stably maintained, but the comparative samples For all of Nos. 1 to 5, the characteristics changed significantly when irradiated with ultraviolet rays, and the initial good characteristics could not be maintained. Furthermore, using a "330 model spectrophotometer" (manufactured by Hitachi, Ltd.), ultraviolet absorption spectra were obtained for each of measurement samples 1 to 3 and comparative measurement samples 1 to 3 obtained in Examples 1 to 3 and Comparative Examples 1 to 3. was measured, and the absorbance ABS1 at a wavelength of 338 nm was determined. Next, light was irradiated in the same manner as above using the same ultra-high pressure mercury lamp as above, and then the ultraviolet absorption spectrum was measured again to determine the absorbance ABS2 at a wavelength of 338 nm. From this, the ratio ABS2/ABS1 between ABS2 and ABS1 was determined. The results are shown in Table 2.

[Table] As is clear from the above Examples and Comparative Examples, the electrophotographic photoreceptor samples of the present invention show less change in characteristics such as acceptance potential, sensitivity, and residual potential due to ultraviolet light irradiation than the comparative samples, and furthermore, changes in the absorption spectrum. It is understood that it shows excellent stability.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention, FIG. 2 is an explanatory sectional view showing another example of the structure of the electrophotographic photoreceptor of the invention, and FIGS. 3 and 4 5 are explanatory cross-sectional views showing still other structural examples of the electrophotographic photoreceptor of the present invention, and FIG. 5 is an ultraviolet absorption spectrum of each of the carbazole derivative and benzotriazole derivative according to the present invention, and conventionally used triarylmethane. FIG. DESCRIPTION OF SYMBOLS 1... Conductive support, 2... Carrier generation layer (CGL), 3... Carrier transport layer (CTL), 4... Photosensitive layer, 5... Intermediate layer, 1A... Insulating substrate, 1B... Conductive layer.

Claims (1)

[Scope of Claims] 1. A photosensitive layer comprising a conductive support and a laminate of a carrier generation layer and a carrier transport layer provided on the conductive support, wherein the carrier transport layer has the following general formula [ ], and at least one of the carrier transport layer or the carrier generation layer has the following general formula []
An electrophotographic photoreceptor comprising a benzotriazole derivative represented by: General formula [] (In the formula, R ₁ represents a substituted or unsubstituted aryl group, R ₂ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group,
represents an amino group, substituted amino group or hydroxyl group,
R ₃ represents a substituted or unsubstituted aryl group, a substituted or unsubstituted thienyl group, or a substituted or unsubstituted carbazolyl group. ) General formula [] (In the formula, R ₄ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an aryl group, or a nitro group, and R ₅ and R ₆ each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or an aryl group. (2) The carrier transport layer contains the benzotriazole derivative, and the content ratio of the benzotriazole derivative to the carbazole derivative in the carrier transport layer is 0.1 to 20% by weight. Electrophotographic photoreceptor. 3 The carrier generation layer contains the benzotriazole derivative, and the content ratio of the benzotriazole derivative in the carrier generation layer is 0.1.
The electrophotographic photoreceptor according to claim 1, wherein the content is 20% by weight.