JPH0513493B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to electrophotographic photoreceptors, and more particularly to improvements in organic photoconductive electrophotographic photoreceptors.

[Prior art]

In the Carlson method electrophotographic copying machine,
After the surface of the photoreceptor is charged, an electrostatic latent image is formed by exposure, the electrostatic latent image is developed with toner, and the visible image is then transferred and fixed onto paper or the like. At the same time, the photoreceptor is subjected to removal of adhered toner, neutralization of static electricity, and surface cleaning, and is used repeatedly over a long period of time. Therefore, as an electrophotographic photoreceptor, it is of course necessary to have electrophotographic properties such as good charging characteristics and sensitivity, and low dark decay, but also printing durability, abrasion resistance, moisture resistance, etc. during repeated use. It is also required to have good physical properties and resistance to ozone generated during corona discharge, ultraviolet rays during exposure, etc. (environmental resistance). Conventionally, as electrophotographic photoreceptors, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide have been widely used. On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years. For example, in Japanese Patent Publication No. 50-10496, poly-N
- describes an organic photoreceptor having a photosensitive layer containing vinylcarbazole and 2,4,7,-trinitro-9-fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the charge generation function and charge transport function to different substances in the photosensitive layer. ing. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible. Many substances have been proposed as charge-generating substances that are effective for such functionally separated electrophotographic photoreceptors. Examples of using inorganic substances include, for example, as described in Japanese Patent Publication No. 16198/1983,
There is amorphous selenium. This is combined with an organic charge transport material. Furthermore, many electrophotographic photoreceptors using organic dyes or organic pigments as carrier generating substances have been proposed. 22834
No. 54-79632, No. 56-116040, and other publications. By the way, known photoreceptors using organic photoconductive substances are generally used for negative charging. The reason for this is that when negative charging is used, the mobility of holes among the charges is large, which is advantageous in terms of photosensitivity and the like. However, it has been found that using such negative charging causes the following problems. That is, the first problem is that ozone is likely to be generated in the atmosphere when negatively charged by the charger, worsening the environmental conditions. Another problem is that positive polarity toner is required for development of negatively charged photoreceptors, but positive polarity toner is difficult to manufacture due to the triboelectrification series with respect to ferromagnetic charged particles. . Therefore, it has been proposed to use a positively charged photoreceptor using an organic photoconductive substance. for example,
In the case of a positively charging photoreceptor in which a charge transport layer is laminated on a charge generation layer and the charge transport layer is formed of a substance with high electron transport ability, the charge transport layer contains trinitrofluorenone, etc., but this substance does not emit light. It is unsuitable because it is cancerous. On the other hand, a photoreceptor for positive charging can be considered in which a charge generation layer is laminated on a charge transport layer with a large hole transport ability, but this has poor printing durability due to the presence of a very thin charge generation layer on the surface side. This is not a practical layer structure. In addition, as a photoreceptor for positive charging, the U.S. Patent No.
No. 3,615,414 discloses a material containing a thiapyrylium salt (charge generating substance) so as to form a eutectic complex with polycarbonate (binder resin). However, with this known photoreceptor,
The disadvantage is that the memory phenomenon is large and ghosts are likely to occur. U.S. Patent No. 3,357,989 also discloses a photoreceptor containing phthalocyanine, but the characteristics of phthalocyanine change depending on the crystal form, and the crystal form must be strictly controlled. Furthermore, it lacks short wavelength sensitivity and has a large memory phenomenon, making it unsuitable for copying machines that use light sources in the visible wavelength range. Due to the above-mentioned circumstances, conventionally, it has been difficult to use a photoreceptor using an organic photoconductive substance for positive charging, and for this reason, it has been used exclusively for negative charging.

[Purpose of the invention]

An object of the present invention is to provide an organic photoconductive electrophotographic photoreceptor that can be used for positive charging, has good sensitivity, has excellent scratch resistance and ozone resistance, and is durable. be.

[Configuration and effects of the invention]

The above-mentioned object of the present invention is to provide an electrophotographic photoreceptor in which a photosensitive layer containing a charge generating substance and a charge transporting substance as main components is provided on a conductive support, and the photosensitive layer contains a compound represented by the following general formula. This was achieved by forcing. general formula In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and X represents an oxygen atom or a sulfur atom. Furthermore, R ₁ , R ₂ , R ₃ , and R ₄ are never hydrogen atoms at the same time. Ozone deterioration of the photoreceptor is caused by repeatedly applied corona discharge, but it is also thought to be enhanced by singlet oxygen generated by exposure.
The degree of ozone oxidation varies depending on the structure of the photosensitive layer of the photoreceptor, the types of charge-generating substances and charge-transporting substances, etc., but charge-transporting substances are more susceptible to oxidation, especially organic photoconductive materials. When using sexual substances, the consequences are extremely large. As a result of intensive studies on improving ozone deterioration (particularly potential drop) of photoreceptors, the present inventors found that the urea or thiourea derivative represented by the above general formula not only significantly prevents ozone oxidation, but also The present inventors have discovered that the present invention also contributes to improving characteristics and physical properties. The present invention will be explained in more detail below. The urea or thiourea derivative used in the present invention is a compound in which at least one of both N and N' hydrogens is substituted with an alkyl group, a cycloalkyl group, or an aryl group. The alkyl group represented by R ₁ to _{R 4} is preferably an alkyl group having 1 to 18 carbon atoms, such as a methyl group, ethyl group, butyl group, hexyl group, octyl group, decyl group, todecyl group, hexadecyl group, Examples include octadecyl group. The cycloalkyl group is preferably a 5- to 7-membered cycloalkyl group, such as a cyclopentyl group or a cyclohexyl group. The aryl group is preferably a phenyl group or a naphthyl group, and these groups may further have a substituent. Typical specific examples of the compounds of the present invention are shown below, but the compounds used in the present invention are not limited thereto.

【table】

[Table] These compounds are easily available commercially as chemical reagents. The amount of the compound represented by the above general formula used in the present invention (hereinafter referred to as the compound of the present invention) varies depending on the layer structure of the photoreceptor and the type of charge transport material. 0.1 to 100% by weight, preferably 1 to 50% by weight,
It is particularly preferably used in a range of 5 to 25% by weight. Next, the structure of the photoreceptor of the present invention will be explained with reference to the drawings. For example, as shown in FIG. 1, the photoreceptor of the present invention has a charge generating material 5 (hereinafter referred to as
CTM) and a charge generation layer 2 (hereinafter referred to as CGL) containing a binder resin as necessary.
) as the lower layer, and a charge transport material 6
(hereinafter sometimes referred to as CTM) and a charge transport layer 3 (hereinafter referred to as CTM) containing a binder resin as necessary.
As shown in FIG. 2, a photosensitive layer 4 having a laminated structure with a CTL 3 as a lower layer and a CGL 2 as an upper layer is provided on a support 1 as shown in FIG. As shown in FIG. 3, examples include those in which a single-layer photosensitive layer 4 containing CGL, CTM, and optionally a binder resin is provided on a support 1, as shown in FIG. In addition, Figure 2 shows a similar layer structure to the upper CGL.
Both CGM and CTM may be contained, a protective layer (OCL) may be provided on the photosensitive layer, and an intermediate layer may be provided between the support and the photosensitive layer. An example is shown in FIG. That is, support 1
An intermediate layer 7 is provided thereon, and DTL3 and CGM5 containing CTM6a and a binder resin,
CGL containing CTM6b and binder resin
This photoreceptor has a photoreceptor layer 4 in which the photoreceptor 2 is laminated, and a protective layer 8 whose main component is a binder is further provided. The compound of the present invention comprises CGL, which constitutes a photoreceptor,
It may be contained in any of the CTL, single-layer photosensitive layer, or OCL, or may be contained in multiple layers. The effect of the present invention is more pronounced in CGL.
This is a photoreceptor with a laminated structure in which CTL is an upper layer and CTL is a lower layer. Next, as the charge generating substance suitable for the present invention, any of inorganic pigments and organic dyes can be used as long as it absorbs visible light and generates free charges. 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, lead sulfide, the following representative examples Organic pigments such as those shown may also be used. (1) Azo pigments such as monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene azo and thiazole azo pigments. (2) Perylene pigments such as perylene anhydride and perylene imide. (3) Anthraquinone or polycyclic quinone pigments such as anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyrantrone derivatives, violanthrone derivatives, and isoviolanthrone derivatives (4) Indigoid pigments such as indigo derivatives and thioindigo derivatives (5) Phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine (6) Carbonium pigments such as diphenylmethane pigment, triphenylmethane pigment, xanthene pigment and acridine pigment (7) Quinone imine such as azine pigment, oxazine pigment and thiazine pigment Cyanine pigments and azomethine pigments (9) Quinoline pigments (10) Nitro pigments (11) Nitroso pigments (12) Benzoquinone and naphthoquinone pigments (13) Naphthalimide pigments (14) ) Perinone pigments such as bisbenzimidazole derivatives Various azo pigments with electron-withdrawing groups are used because of their good electrophotographic properties such as sensitivity, memory phenomenon, and residual potential, but polycyclic quinones are preferred due to their ozone resistance. pigments are most preferred. Although the details are unknown, this is probably because the azo group is susceptible to ozone oxidation and the electrophotographic properties deteriorate, whereas polycyclic quinones are inert to ozone. As the azo pigment used in the present invention,
For example, there are compounds shown in the following exemplified compound groups [] to [].

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[Table] Furthermore, the following exemplified compound groups [] to [] consisting of polycyclic quinone pigments can be most preferably used as CGM.

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[Table] Next, there are no particular limitations on charge transport substances that can be used in the present invention, but examples include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives,
Imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxazolone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, poly-N-vinyl Carbazole, poly-1
-vinylpyrene, poly-9-vinylanthracene, etc. However, it is preferable to use a CTM that has an excellent ability to transport holes generated by light irradiation to the support side and is suitable for combination with the carrier generating substance. Examples of such CTM include the following exemplified compound group [] or [ ] is used.

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[Table] In addition, pyrazoline compounds shown in the following exemplified compounds [] can also be used as CTMs.

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[Table] In addition, the following exemplified compound group as CTM []
Amine derivatives represented by can also be used.

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[Table] The layer structure of the photosensitive layer of the photoreceptor of the present invention includes the above-mentioned laminated structure and single layer structure.
Either CTL, CGL, single layer photosensitive layer or OCL,
Alternatively, the plurality of layers may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, etc. Examples of electron-accepting substances that can be used in the photoreceptor of the present invention include succinic anhydride, maleic anhydride,
Dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic 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, brumanil, 2-
Methylnaphthoquinone, dichlorodicyanoparabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-fluorenylidene [dicyanomethylenemalonodinitrile],
Polynitro-9-fluorenylidene-[dicyanomethylenemalonodinitrile], picric acid, o-
Nitrobenzoic acid, p-nitrobenzoic acid, 3,5-
dinitrobenzoic acid, pentafluorobenzoic acid, 5
-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid and the like. Examples of binder resins that can be used in the photosensitive layer in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate resin. , addition polymerization resins such as 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, vinyl chloride-vinyl acetate-maleic anhydride In addition to insulating resins such as copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazone may be used. Further, the intermediate layer functions as an adhesive layer or a barrier layer, and in addition to the binder resin, for example, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-anhydrous Maleic acid copolymers, casein, N-alkoxymethylated nylon, starch, etc. are used. Next, the conductive support supporting the photosensitive layer includes a metal plate such as aluminum or nickel, a metal drum or metal foil, a plastic film deposited with aluminum, tin oxide, indium oxide, etc., or paper coated with a conductive substance. Films or drums such as plastic can be used. CGL can be provided by vacuum-depositing the above-mentioned CGM onto the support, or by applying a solution or dispersion of CGM alone or together with a suitable binder resin in a suitable solvent, and drying it. When CGL is formed by dispersing the CGM, the CGM is preferably in the form of powder having an average particle size of 2 μm or less, preferably 1 μm or less. That is, if the particle size is too large, dispersion in the layer will be poor, and some of the particles will protrude from the surface, resulting in poor surface smoothness. Toner particles tend to adhere to the toner, causing a toner filming phenomenon. However, if the above particle size is too small, it tends to aggregate, which increases the resistance of the layer, increases crystal defects and reduces sensitivity and repeatability, or there is a limit to miniaturization. Lower limit of diameter
It is desirable to set it to 0.01 μm. CGL can be provided by the following method. That is, this is a method in which the CGM described above is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., a binder resin is added, and a dispersion obtained by mixing and dispersing is applied. When the particles are dispersed under the action of ultrasound in this method, uniform dispersion is possible. Solvents used in the formation of CGL include, for example, N,N-dimethylformamide, benzene, toluene, xylene, monochlorobenzene, 1,2
-dichloroethane, dichloromethane, 1,1,2
-trichloroethanetetrahydrofuran, methyl ethyl ketone, ethyl acetate, butyl acetate, and the like. CGM per 100 weight of binder resin in CGL
The amount is 20 to 200 parts by weight, preferably 25 to 100 parts by weight. If the CGM is less than this, the photosensitivity will be low and the residual potential will increase, and if it is more than this, the dark decay will increase and the acceptance potential will decrease. The thickness of the CGL formed in the above manner is
In the case of a configuration for positive charging, it is preferably 1 to 10 μm, particularly preferably 3 to 7 μm, and in the case of a configuration for negative charging, it is preferably 0.01 to 10 μm, particularly preferably 0.1
~3 μm. That is, in a configuration for positive charging, since the CGL is a surface layer, it lacks scratch resistance, and in order to improve durability, it is necessary to increase the thickness of the CGL film, but this causes a decrease in sensitivity. As a means of controlling this
CTM is added to CGL, but this CTM is
Since it has a structure that is more susceptible to biozone oxidation than CGM, it is easily deteriorated by ozone and the durability of the photoreceptor is impaired. The present invention eliminates this vicious cycle by adding the compound of the present invention. In addition, CTL is prepared by applying the above-mentioned CTM in the same manner as the above-mentioned CGL (i.e., applying it alone or by dissolving and dispersing it together with the above-mentioned binder resin).
dry). CTM per 100 parts by weight of binder resin in CTL
is 20 to 200 parts by weight, preferably 30 to 150 parts by weight. If the CTM content is less than this, the photosensitivity will be poor and the residual potential will tend to be high, and if it is more than this, the solvent solubility will be poor. The thickness of the CTM to be formed is preferably 5 to 5.
50 μm, particularly preferably 5 to 30 μm. Also,
The film thickness ratio of CGL and CTL is preferably 1:(1 to 30). In the case of the single-layer structure, the proportion of CGM contained in the binder resin is 20 to 200 parts by weight, preferably 25 to 100 parts by weight, based on 100 parts by weight of the binder resin. If the CGM content is less than this, the photosensitivity will be low and the residual potential will increase, and if it is more than this, the dark decay and acceptance potential will decrease. Next, the ratio of CTM to binder resin is 20 parts by weight per 100 parts by weight of binder resin.
~200 parts by weight, preferably 30 to 150 parts by weight. If the CTM content is less than this, the photosensitivity will be poor and the residual potential will tend to be high, and if it is more than this, the solvent solubility will be poor. The weight ratio of CTM to CGM in the single-layer photosensitive layer is preferably 1:3 to 1:2. In the present invention, the protective layer provided as necessary has a volume resistivity of 10 ⁸ Ω・cm or more as a binder,
Preferably 10 ¹⁰ Ω・cm or more, more preferably 10 ¹³
A transparent resin with a resistance of Ω・cm or more is used. Further, the binder contains at least 50% by weight of a resin that is cured by light or heat. Such resins that harden with light or heat include:
Examples include thermosetting acrylic resins, silicone resins, epoxy resins, urethane resins, urea resins, phenolic resins, polyester resins, alkyd resins, melamine resins, photocurable/cinnamic acid resins, and copolymerized or cocondensed resins thereof. , as well as photo- or thermosetting resins used in electrophotographic materials. During the protection, a thermoplastic resin may be contained in an amount of less than 50% by weight, if necessary, for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Such thermoplastic resins include:
For example, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, butyral resin, polycarbonate resin, silicone resin, or copolymer resins thereof,
For example, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, polymeric organic semiconductors such as poly-N-vinylcarbazole, and other thermoplastic resins used in electrophotographic materials. Everything is used. Further, the protective layer may contain an electron-accepting substance, and may also contain an ultraviolet absorber or the like for the purpose of protecting the CGM if necessary. Applied and dried by spray coating, blade coating, roll coating, etc. to a thickness of 2 μm or less, preferably
Formed to a layer thickness of 1 μm or less.

【Example】

EXAMPLES The present invention will be explained below with reference to Examples, but the embodiments of the present invention are not limited thereby. Example 1 A conductive support made of polyester film laminated with aluminum foil was coated with a layer of vinyl chloride-vinyl acetate-maleic anhydride copolymer (Eslec MF-10, manufactured by Sekisui Chemical Co., Ltd.).
An intermediate layer of 0.1 μm was formed. Next, CTM (-75)/polycarbonate resin (Vanlite L-1250 <manufactured by Teijin Chemicals) = 75/100
A 1,2-dichloroethane solution containing 16.5% by weight (weight ratio) was dip-coated onto the intermediate layer and dried to obtain a CTL with a thickness of 15 μm. 4,10-dibromoanthrone (-3)/panlarite L- was then sublimated as CGM.
1250 = 50/100 (weight ratio) was ground in a ball mill for 24 hours, 1,2-dichloroethane was added to make it 9% by weight, and the mixture was further dispersed in a ball mill for 24 hours.
CTM (-75) to 75 against Panlite L-1250
% by weight and the compound (4) of the present invention was added in an amount of 10% by weight based on CTM. Monochlorobenzene was added to this dispersion to give a monochlorobenzene/1,2-dichloroethane ratio of 3/7 (volume ratio), and a CGL with a thickness of 5 μm was formed by spray coating on the CTL. A photoreceptor of the present invention having a photosensitive layer having the following structure was obtained. Comparative Example 1 A comparative photoreceptor was obtained in the same manner as in Example 1 except that CGL compound (4) was removed. Example 2 Compound (10) was substituted for compound (4) in Example 1.
A photoreceptor of the present invention was obtained in the same manner as in Example 1 except that . Example 3 A thermosetting acrylic-melamine-epoxy (1:1:1) resin was placed on a photoreceptor (same as the photoreceptor of Comparative Example 1) obtained by removing compound (4) from the CGL of Example 1.
A coating solution obtained by dissolving 1.55 parts by weight and 0.155 parts by weight of the compound (4) of the present invention in 100 parts by weight of a mixed solvent of monochlorobenzene/1,1,2-trichlorothane (1/1 volume ratio) was sprayed. Coated and dried to 1μm
A thick protective layer was formed to obtain a photoreceptor of the present invention. Example 4 A silicone hard coat primer was applied onto the photoconductor obtained by removing compound (4) from the CGL of Example 1.
Spray PH91 (manufactured by Toshiba Silicon Co., Ltd.) to a thickness of 0.1 μm, and then apply silicone hard coat Tosguard 510 (manufactured by Toshiba Silicon Co., Ltd.) and compound (4) at 10 parts by weight per 100 parts by weight of resin. The solution added in the above manner was spray coated and dried to form a protective layer of 1 μm to obtain a photoreceptor of the present invention. Example 5 An intermediate layer exactly the same as in Example 1 was formed on a conductive support made of polyester film laminated with aluminum foil. Next, as a CTL coating solution, a solution obtained by dissolving butyral resin (Erex BX-1, manufactured by Sekisui Chemical Co., Ltd.) in methyl ethyl ketone so that the amount was 8% by weight and CTM (-75) was 6% by weight was applied onto the intermediate layer. It was applied and dried to form a 10 μm thick CTL. Next, apply 0.2 g of CGM (-7) to Paint Conditioner (manufactured by Red Devil).
The carbonate resin (Panlite L-1250, mentioned above) was mixed with 0.5% of the 1,2-dichloroethane/1,1,2-tricloethane mixed solvent.
Add 8.3g of the solution dissolved to make 3% by weight.
After dispersing for a minute, add polycarbonate resin,
CTM (−75) and compound (4), each at 3.3
19.1 g of a solution obtained by dissolving in a mixed solvent of 1,2-dichloroethane/1,1,2-trichloroethane to give a concentration of 2.6% by weight and 0.26% by weight.
was added and dispersed for an additional 30 minutes. The thus obtained dispersion was spray-coated onto the CTL and dried to form a 5 μm thick CGL, thereby obtaining a photoreceptor according to the present invention having a photosensitive layer having a laminated structure. Comparative Example 2 A comparative photoreceptor was obtained in the same manner as in Example 5 except that compound (4) in CGL was removed. Example 6 Compound (10) was substituted for compound (4) in Example 5.
A photoreceptor of the present invention was obtained in the same manner as in Example 5 except that . Example 7 A protective layer containing the compound (4) used in Example 3 was provided on a photoreceptor (same as the photoreceptor of Comparative Example 2) obtained by removing compound (4) from the CGL of Example 5. A photoreceptor of the invention was obtained. Example 8 A protective layer containing the compound (4) used in Example 4 was provided on a photoreceptor obtained by removing compound (4) from the CGL of Example 5 to obtain a photoreceptor of the present invention. Example 9 An intermediate layer exactly the same as in Example 1 was formed on a polyester film on which aluminum was vapor-deposited. Next, 40 g of sublimed 4,10-dibromoanthrone (-3) was milled at 40 rpm in a porcelain ball mill.
Grind for 24 hours and use Panlite L-1250 (mentioned above).
20 g and 1,300 ml of 1,2-dichloroethane were added, and the mixture was further dispersed for 24 hours to obtain a CGL coating solution. This was applied onto the intermediate layer to form a CGL with a film thickness of 1 μm. Next, CTM (-61) 7.5g, Panlite L-
A solution prepared by dissolving 10 g of 1250 and 0.75 g of compound (4) in 80 ml of 1,2-dichloroethane was applied onto the CGL to form a CTL having a thickness of 15 μm, thereby producing a photoreceptor of the present invention. Comparative Example 3 A comparative photoreceptor was obtained in the same manner as in Example 9 except that compound (4) in CTL was removed. Example 10 On a conductive support made of polyethylene terephthalate with a thickness of 100 μm on which aluminum was vapor-deposited,
An intermediate layer exactly the same as in Example 1 was formed. Then bisazo compound (-7) as CGL
A dispersion in which 1.5 g of 1,2-dichloroethane/monoethanolamine (1000/1 volume ratio) was dispersed in 100 ml of a mixed solvent using a ball mill for 8 hours was coated on the above intermediate layer and dried sufficiently to form a 0.3 μm thick layer. A CGL was established. Then styryl compound (−43) as CTM
A solution prepared by dissolving 11.25 g of Panlite L-1250 (above) and 1.125 g of compound (4) in 100 ml of 1,2-dichloroethane was applied onto the CGL and sufficiently dried to form a 15 μm thick CTL. , a photoreceptor of the present invention was prepared. Comparative Example 4 A comparative photoreceptor was prepared in the same manner as in Example 10 except that compound (4) in CTL was removed. Example 11 In place of compound (4) in Example 10, compound (10)
A photoreceptor of the present invention was obtained in the same manner as in Example 10 except that . The ozone resistance of the 14 types of photoreceptors thus obtained was evaluated in the following manner. That is, an ozone generator (manufactured by Nippon Ozone Co., Ltd., 0-1-2
Using an ozone fatigue tester equipped with an ozone monitor (manufactured by Ebara Jitsugyo Co., Ltd., model EG-2001) and a photoreceptor mounted at an ozone concentration of 90 ppm, the following characteristic tests were conducted. In other words, a voltage of +6KV is applied for a positively charged photoreceptor, and -6KV is applied for a negatively charged photoreceptor, the photosensitive layer is charged by corona discharge for 5 seconds, and then left for 5 seconds (the potential at this time is set to the initial value). Then, the surface of the photosensitive layer was irradiated with light from a tungsten lamp with an illumination intensity of 14 lux, and this operation was repeated ₁₀₀ times. The residual potential V _I was measured after 100 times, and ozone resistance was evaluated by V _I /V _O ×100 (%). The exposure amount required to attenuate the initial potential from ±600 V to ±100 V, E ⁶⁰⁰ ₁₀₀ (lux seconds), was also measured. The larger the value of V _I /V _O ×100 (%), the
It shows less ozone deterioration, and E ⁶⁰⁰ ₁₀₀ (The smaller the lux-second value, the more sensitive the photoreceptor is. The results are shown in the attached table.

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[Table] As is clear from the table, by adding the compound of the present invention, the potential drop due to corona charging in the presence of ozone is significantly improved. Moreover,
It can be seen that the addition of the compound of the present invention causes almost no decrease in sensitivity.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views of the photoreceptor of the present invention. 1... Support, 2... Charge generating layer (CGL), 3
...Charge transport layer (CTL), 4...Photosensitive layer, 5...
Charge generating material (CGM), 6... Charge transporting material (CTM), 7... Intermediate layer, 8... Protective layer (OCL).

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor in which a photosensitive layer containing a charge generating substance and a charge transporting substance as main components is provided on a conductive support, in which a compound represented by the following general formula is incorporated in the photosensitive layer. An electrophotographic photoreceptor comprising: general formula [In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and X represents an oxygen atom or a sulfur atom. Furthermore, R ₁ , R ₂ , R ₃ and R ₄ are never hydrogen atoms at the same time. ]