JPH0544023B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to electrophotographic photoreceptors, and more particularly to electrophotographic photoreceptors containing a low molecular weight organic photoconductor that provides improved electrophotographic properties. [Prior Art] Various organic photoconductive polymers, including polyvinylcarbazole, have been proposed as photoconductive materials for use in electrophotographic photoreceptors, but these polymers have a disadvantage in comparison to inorganic photoconductive materials. Although it has excellent film formability and light weight, it has been difficult to put it into practical use until now because sufficient film formability has not yet been obtained, and sensitivity, durability, and environmental This is because they are inferior to inorganic photoconductive materials in terms of stability due to changes. Also, hydrazone compounds disclosed in US Pat. No. 4,150,987, triarylpyrazoline compounds described in US Pat. No. 3,837,851, JP-A-51-94828, JP-A-51-94829, etc. Low-molecular organic photoconductors have been proposed, such as the 9-styrylanthracene compound described in . These low-molecular-weight organic photoconductors have been able to overcome the film-forming drawbacks that had been a problem in the field of organic photoconductive polymers by appropriately selecting the binder used. , cannot be said to be sufficient in terms of sensitivity. For this reason, in recent years, a laminated structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer has been proposed. An electrophotographic photoreceptor with this laminated structure as a photosensitive layer has high sensitivity to visible light, charge retention ability,
It has become possible to improve aspects such as surface strength. Such an electrophotographic photoreceptor is known, for example, from Japanese Patent Application Laid-Open No. 1983
Examples include laminations of an azo compound and a styryl compound, which are disclosed in Japanese Patent Application Laid-open No. 198043, Japanese Patent Application Laid-Open No. 1980-110837, and Japanese Patent Application Laid-open No. 161247-1984. However, electrophotographic photoreceptors using conventional low-molecular organic photoconductors in the charge transport layer do not necessarily have sufficient sensitivity and characteristics, and when repeatedly charged and exposed, bright area potential and dark area potential change. There is a large potential fluctuation that needs to be improved. [Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor that eliminates the above-mentioned drawbacks or disadvantages, to provide a novel organic photoconductor, and to provide a charge generation layer and a charge transport layer. The object of the present invention is to provide a novel charge transport material in a laminated photosensitive layer with functionally separated functions. [Means for Solving the Problems, Effects] The present invention provides an electrophotographic photoreceptor in which a photosensitive layer is laminated on a conductive support, wherein the photosensitive layer contains a compound represented by the following general formula (). It consists of a photographic photoreceptor. In the formula, R ₁ and R ₂ represent an alkyl group, an aryl group, or an aralkyl group that may have a substituent, and may be the same or different. R ₃ is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a -SR ₇ group that may have a substituent (R ₇ represents an alkyl group, an aryl group, or an aralkyl group. R ₄ , R ₅ and R ₆ is a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group,
It represents a halogen atom or a _-SR7 group, and may be the same or different. However, when R ₁ and R ₂ have a substituent, at least one of R ₃ , R ₄ , R ₅ , and R ₆ is a -SR ₇ group, and two or more -SR ₇ groups In this case, R ₇ need not be the same. X represents an ethylene group, a vinylene group, an oxygen atom, an amino group (= _NR8 ) or a sulfur atom, and _R8 represents an alkyl group, an aryl group or an aralkyl group. Specifically, in R ₁ and R ₂ , alkyl groups include methyl, ethyl, propyl, butyl, etc., aryl groups include phenyl, naphthyl, etc., and aralkyl groups include benzyl, naphthylmethyl, etc. Furthermore, substituents for the above groups include halogen atoms such as fluorine atom, chlorine atom, iodine atom, and bromine atom, alkyl groups such as methyl, ethyl, propyl, and butyl, and alkoxy groups such as methoxy, ethoxy, and phenoxy. groups, and for R ₇ , methyl, ethyl, propyl, butyl, phenyl, naphthyl, benzyl,
Examples include groups such as naphthylmethyl. Also in the case of R ₃ , R ₄ , R ₅ , and R ₆ , the same groups as R ₁ can be specifically mentioned. Further, in the case of R ₈ , specific examples include the same groups as R ₇ . Representative examples of the compounds represented by the general formula () are listed below. Compound example (1) Compound example (2) Compound example (3) Compound example (4) Compound example (5) Compound example (6) Compound example (7) Compound example (8) Compound example (9) Compound examples (10) Compound examples (11) Compound examples (12) Compound examples (13) Compound examples (14) Compound examples (15) Compound examples (16) Compound examples (17) Compound examples (18) Compound examples (19) Compound examples (20) Compound examples (21) Compound example (22) Compound example (23) Compound examples (24) Compound examples (25) Compound examples (26) Compound examples (27) Compound examples (28) Compound examples (29) Compound examples (30) Compound examples (31) Compound examples (32) Compound examples (33) Compound examples (34) (There is no compound example (35)) Compound example (36) Compound examples (37) Compound examples (38) Compound examples (39) Compound examples (40) Compound examples (41) (There is no compound example (42)) Compound example (43) Compound examples (44) Compound examples (45) Compound examples (46) Compound examples (47) Synthesis example (synthesis of compound example (18)) The above formula benzyl chloride () was converted into a Wittig reagent (), which was nitrated (), reacted with dibenzosuberenone to obtain the nitro form (), and further reduced to obtain the amino form (). Ullmann reaction was performed with this and 4-(methylmercapto)aniline to obtain the target compound (). Yield 17.1% Melting point 129.2℃ Elemental analysis C ₃₆ H ₂₉ NS ₂ Mw: 539.76 Measured value (%) Theoretical value (%) C 80.17 80.11 H 5.51 5.42 N 2.52 2.60 S 11.80 11.88 For compounds other than the synthesis examples, Generally synthesized using similar techniques. In a preferred embodiment of the present invention, a compound represented by the above general formula () is used as a charge transporting substance in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. The charge transport layer in the present invention has the general formula ()
It is preferable to form the film by applying a solution in which the compound represented by and a binder are dissolved in a suitable solvent and drying the solution. Examples of the binder used here include polyarylate, polysulfone, polyamide, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester, alkyd resin, polycarbonate, polyurethane, or Mention may be made of copolymers such as styrene-bitadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, and the like. In addition to such insulating polymers, organic photoconductive polymers such as polyvinylcarbazole, polyvinylanthracene, and polyvinylpyrene can also be used. The blending ratio of this binder and the specific charge transport substance is 10 parts by weight of the charge transport substance per 100 parts by weight of the binder.
The amount is preferably 500 parts by weight. The charge transport layer is electrically connected to the charge generation layer described below, and has the function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. are doing. At this time, this charge transport layer may be laminated on or under the charge generation layer. However, it is desirable that the charge transport layer is laminated on the charge generation layer. Since this charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 40 μm, but the preferred range is 10 to 30 μm. The organic solvent used to form such a charge transport layer varies depending on the type of binder used, and is preferably selected from those that do not dissolve the charge generation layer or the subbing layer described below. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol;
Ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, and methyl acetate. , esters such as ethyl acetate,
methylene chloride, dichloroethylene, carbon tetrachloride,
Aliphatic halogenated hydrocarbons such as trichloroethylene, aromatics such as benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying is generally preferably carried out at a temperature of 30 to 200° C. for 5 minutes to 2 hours, either stationary or under ventilation. The charge transport layer in the present invention may contain various additives. For example, plasticizers such as diphenyl, m-terphenyl, dibutyl phthalate, silicone oil, grafted silicone polymers, surface lubricants such as various fluorocarbons, potential stabilizers such as dicyanovinyl compounds, carbazole derivatives, β-carotene, Ni
Complexes, antioxidants such as 1,4-diazabicyclo[2,2,2]octane, and the like can be mentioned. The charge generation layer in the present invention includes inorganic charge generation substances such as selenium, selenium-tellurium, and amorphous silicone; cationic dyes such as pyrylium dyes, thiapyrylium dyes, azulenium dyes, thiacyanine dyes, and quinocyanine dyes;
Polycyclic quinone pigments such as squbarium salt dyes, phthalocyanine pigments, anthorone pigments, dibenzpyrenequinone pigments, and pyranthrone pigments, indigo pigments, quinacridone pigments,
Materials selected from organic charge-generating substances such as azo pigments can be used alone or in combination as a vapor deposited layer or a coating layer. Among the above-mentioned charge-generating substances, there are a wide variety of azo pigments in particular, and typical structural examples of particularly effective azo pigments will be described below. The general formula of an azo pigment is shown below as A for the central skeleton and Cp for the coupler part, where n
is set to 1 or 2, and specific examples are given. A(-N=N-Cp)n A specific example of A is A-1 (R: hydrogen atom, chlorine atom, methoxy group) A-2 (R: hydrogen atom, cyano group) A-3 (R: hydrogen atom, cyano group) A-4 (X: oxygen atom, sulfur atom R: hydrogen atom, methyl group, chlorine atom) A-5 (X: oxygen atom, sulfur atom R ₁ , R ₂ : hydrogen atom, methyl group, chlorine atom) A-6 (R ₁ , R ₂ : Hydrogen atom, methyl group, chlorine atom, etc., R ₃ : Hydrogen atom, methyl group,

[Formula]) A-7 A-8 (X: oxygen atom, sulfur atom) A-9 (X: oxygen atom, sulfur atom) A-10 (X: oxygen atom, sulfur atom) A-11 (R: hydrogen atom, methyl group) A-12 (X:= _CH2 , oxygen atom, sulfur atom,= _SO2 ) A-13 A-14 (X: oxygen atom, sulfur atom) A-15 A-16 (X: oxygen atom, sulfur atom) A-17 A-18 A-19 A-20 A-21 (R: hydrogen atom, methyl group) Also, as a specific example of Cp, Cp-1 (R: hydrogen atom, halogen atom, alkoxy group, alkyl group, nitro group, etc. n: 1 or 2) Cp-2 (R: methyl group, ethyl group, propyl group, etc.) Cp-3 [R: alkyl group,

[Formula] (R': hydrogen atom, halogen atom, alkoxy group, alkyl group, nitro group, etc.)] Cp-4

[Formula] (R: hydrogen atom, halogen atom, alkoxy group, alkyl group, nitro group, etc.) Cp-5

[expression] or

【formula】 (R: alkyl group, aryl group, etc.) Cp-6

[expression] or

[Formula] Cp−7 (R ₁ , R ₂ : hydrogen atom, halogen atom, alkoxy group, alkyl group, nitro group, etc. n: 1 or 2), and the like. The central skeleton A and the coupler Cp form a pigment serving as a charge-generating substance by appropriate combination. The charge-generating layer can be formed by dispersing the charge-generating substance described above in a suitable binder and coating it on a support, or by forming a vapor-deposited film using a vacuum evaporation device. It can be formed by twisting it. The binder can be selected from a wide range of insulating resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and pyrivinylpyrene. Preferably polyvinyl butyral, polyarylate (such as a polycondensate of bisphenol A and phthalic acid), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, Examples include epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, and the like. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. Organic solvents used during coating include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, dimethyl Sulfoxides such as sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, and aliphatic halogenated compounds such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene. Hydrocarbons or aromatics such as benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, etc. can be used. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying is generally preferably carried out at a temperature of 30 to 200° C. for 5 minutes to 2 hours, either stationary or under ventilation. The charge generation layer contains as much of the organic photoconductor as possible in order to obtain sufficient absorbance and contains a thin film layer, e.g. 5μm
Hereinafter, it is preferable to use a thin film layer having a thickness of preferably 0.01 to 1 μm. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping, but are transferred to the charge transport layer. This is due to the need for injection. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a support having a conductive layer. As the support having a conductive layer, the support itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel,
Vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be coated by vacuum evaporation method. Plastics with formed layers (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluorinated ethylene, etc.), conductive particles (e.g. aluminum powder, titanium oxide, tin oxide, zinc oxide,
A support obtained by coating plastic or the above-mentioned conductive support with carbon black, silver particles, etc.) together with a suitable binder, a support obtained by impregnating plastic or paper with conductive particles, a plastic containing a conductive polymer, etc. may be used. I can do it. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing layer is casein, polyvinyl alcohol,
It can be formed from nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, and the like. The thickness of the undercoat layer is 0.1 to 5 μm, preferably 0.5 to 5 μm.
3 μm is appropriate. When using a photoreceptor in which a conductive support, a charge generation layer, and a charge transport layer are laminated in this order, the charge transport compound in the present invention has hole transport properties, so it is necessary to negatively charge the surface of the charge transport layer. can be,
When exposed to light after being charged, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface to neutralize the negative charge, resulting in attenuation of the surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use positively charged toner. In another embodiment of the present invention, the aforementioned disazo pigments or the disazo pigments described in U.S. Pat.
The photoconductivity of pyrylium dyes, thiapyrylium dyes, selenapyrylium dyes, benzopyrylium dyes, benzothiapyryllium dyes, naphtopyrylium dyes, naphthothiapyrylium dyes, etc. disclosed in 3567438, 3586500, etc. Pigments and dyes can also be used as sensitizers. In another specific example, a eutectic complex of a pyrylium dye and an electrically insulating polymer having an alkylidene diarylene moiety as disclosed in US Pat. No. 3,684,502 and the like can be used as a sensitizer. This eutectic complex is composed of, for example, 4-[4-bis(2-chloroethyl)aminophenyl]-2,6-diphenylthiapyrylium perchlorate and poly(4,
4'-isopropylidene diphenylene carbonate) in a halogenated hydrocarbon solvent such as dichloromethane, chloroform, carbon tetrachloride, 1,1-
dichloroethane, 1,2-dichloroethane, 1,
After dissolving in 1,2-trichloroethane, chlorobenzene, bromobenzene, 1,2-dichlorobenzene, etc., add a non-polar solvent such as hexane, octane, decane, 2,2,4-trimethylbenzene, ligroin, etc. can be obtained as a particulate eutectic complex by adding . The electrophotographic photoreceptor in this specific example includes styrene-butadiene copolymer, silicone resin,
Contains vinyl resin, vinylidene chloride-acrylonitrile copolymer, styrene-acrylonitrile copolymer, vinyl acetate-vinyl chloride copolymer, polyvinyl butyral, polymethyl methacrylate, poly-N-butyl methacrylate, polyesters, cellulose esters, etc. as a binder. I can do it. The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, and electrophotographic plate making systems. The electrophotographic photoreceptor of the present invention has the advantage of high sensitivity and small fluctuations in bright area potential and dark area potential when repeatedly charged and exposed. [Examples] Example 1 A coating solution was prepared by dispersing 5 g of a disazo pigment represented by the following structural formula together with a solution obtained by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 100 ml of scrohexanone in a sand mill for 24 hours. Apply this coating solution on an aluminum sheet until the dry film thickness is
A charge generation layer was formed by coating with a Meyer bar to a thickness of 0.2 μm. Next, 10 g of Compound Example (7) as a charge transport material and 10 g of polycarbonate (average molecular weight 20,000) were dissolved in 70 g of chlorobenzene, and this solution was applied onto the charge generation layer using a Mayer bar, and the dried film was coated. Thickness
A charge transport layer of 20 μm was formed to produce an electrophotographic photoreceptor. The electrophotographic photoreceptor thus created was sold to Kawaguchi Electric Co., Ltd.
Using an electrostatic copying paper tester Model-SP-428, the paper was corona charged at 5KV using a static method, held in a dark place for 1 second, and then exposed to light at an illuminance of 20 lux.
The charging characteristics were investigated. As for charging characteristics, the surface potential (V ₀ ) and the exposure amount (E1/2) required to attenuate the potential (V ₁ ) by 1/2 when dark decayed for 1 second were measured. Furthermore, in order to measure the fluctuations in bright area potential and dark area potential during repeated use, the electrophotographic photoreceptor prepared in this example was
Attach it to the -3525 photosensitive drum cylinder,
5,000 copies were made using the same machine, and changes in the light area potential (V _L ) and dark area potential (V _D ) at the initial stage and after 5,000 copies were measured. Note that the initial V _D and V _L were set to −700 V and −200 V, respectively.

[Table] Examples 2 to 14 In each of these Examples, in place of the charge transport compound example (7) used in Example 1, compound examples (1), (4),
(14), (18), (21), (27), (29), (31), (
33),
An electrophotographic photoreceptor was prepared using (38), (40), (44), and (47) and a pigment having the structural formula below as a charge generating substance, with the other conditions being the same as in Example 1. . The electrophotographic properties of each photoreceptor were measured in the same manner as in Example 1. The results will be described later. Comparative Examples 1 to 3 For comparison, electrophotographic photoreceptors were prepared in the same manner as in Example 2 except that a compound having the following structure was used as a charge transport material, and the electrophotographic properties were measured in the same manner. The results will be described later. Comparative compound example (1) (Japanese Patent Application Laid-open No. 198043/1983) Comparative compound example (2) (Japanese Patent Application Laid-open No. 110837/1983) Comparative compound example (3) (Japanese Unexamined Patent Publication No. 161247/1983)

【table】

【table】

【table】

【table】

[Table] From the above results, the electrophotographic photoreceptor of the present invention has
By using the compound represented by the general formula (),
Compared to the electrophotographic photoreceptor of the comparative example, the sensitivity is improved, and potential fluctuations due to repeated use are significantly small, and stability is particularly excellent. Example 15 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 22.2 ml of water) was coated on an aluminum cylinder by a blade coating method to form a subbing layer with a dry film thickness of 1 μm. Next, 10 g of a charge generating substance shown by the following structural formula, Butyral resin (butyralization degree 63 mol%) 5
g and 200 g of cyclohexanone were dispersed for 48 hours using a ball mill disperser. This dispersion was applied onto the previously formed subbing layer by a blade coating method to form a charge generation layer with a dry film thickness of 0.15 μm. Next, 10 g of Compound Example (16) and 10 g of polymethyl methacrylate (average molecular weight 50,000) were dissolved in 70 g of chlorobenzene, and the solution was coated on the previously formed charge generation layer by a blade coating method to give a dry film thickness of 19 μm. A charge transport layer was formed. A corona discharge of -5 KV was applied to the electrophotographic photoreceptor thus prepared. The surface potential at this time was measured (initial potential V ₀ ). Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 1 second. Sensitivity was evaluated by measuring the amount of exposure (E1/2, microjoule/cm ² ) required to attenuate the potential V ₁ after dark decay to 1/2. At this time, gallium/aluminum/
An arsenic ternary semiconductor laser (output: 5 mw, oscillation wavelength 780 nm) was used. Show the results. V ₀ : -695V V ₁ : -685V E1/2: 1.3 microjoules/cm ² Next, we used a laser beam printer (manufactured by Canon Inc.), which is a reversal development type electrophotographic printer equipped with the same semiconductor laser as above. , LBP-CX) was set in place of the photoreceptor of LBP-CX, and an actual image forming test was conducted. The conditions are: surface potential after primary charging: -700V, surface potential after image exposure: -150V (exposure amount: 2.0 microjoules/cm ² ), transfer potential: +700V, developer polarity, negative polarity, process speed: 50nm. /sec, development conditions (development bias): -450V, image exposure scan method: image scan, exposure before primary charging:
The entire surface was exposed to red light at 50 lux, sec. Image formation was performed by line scanning a laser beam in accordance with character and image signals, and good prints were obtained for both characters and images. Furthermore, when printing 3000 images continuously, good prints were obtained that were stable from the initial stage up to 3000 sheets. Example 16 4-(4-dimethylaminophenyl)-2,6-
3 g of diphenylthiapyrylium perchlorate and 5 g of Compound Example (11) were mixed into a toluene (50 parts by weight)-dioxane (50 parts by weight) solution of polyester (Polyester Adhesive 49000, manufactured by DuPont).
The mixture was mixed in 100 ml and dispersed in a ball mill for 6 hours.
This dispersion was applied onto an aluminum sheet using a Mayer bar so that the film thickness after drying was 15 μm. The electrophotographic properties of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. Show the results. V ₀ : -700V V ₁ : -695V E1/2: 1.5lux, sec Initial V _D : -695V V _L : -85V After 5,000 sheets durability V _D : -690V V _L : -95V Example 17 4-( 4-dimethylaminophenyl)-2,6-
After fully dissolving 3 g of diphenylthiapyrylium perchlorate and 3 g of poly(4,4'-isopropylidene diphenylene carbonate) in 200 ml of dichloromethane, 100 ml of toluene was added to precipitate a eutectic complex. After filtering this precipitate, add dichloromethane to redissolve it, and then add n to this solution.
- 100 ml of hexane was added to obtain a precipitate of the eutectic complex. 5g of this eutectic complex and 2g of polyvinyl butyral
The mixture was added to 95 ml of a methanol solution containing 100 ml of methanol, and dispersed using a ball mill dispersion machine for 6 hours. This dispersion was spread on an aluminum plate with a casein layer so that the film thickness after drying was
A charge generation layer was formed by coating with a Mayer bar to a thickness of 0.4 μm. Next, a cover layer of a charge transport layer was formed in the same manner as in Example 1 except that Compound Example (36) was used on the charge generation layer. The electrophotographic properties of the thus produced electrophotographic photoreceptor were measured in the same manner as in Example 1. Show the results. V ₀ : −700V V ₁ : −680V E1/2: 2.3lux, sec Initial V _D : −695V V _L : −105V After 5,000 sheets durability V _D : −680V V _L : −120V Example 18 On aluminum plate An ammonia aqueous solution of casein (described above) was applied to the substrate using a Mayer bar to form a subbing layer with a dry thickness of 1 μm. The charge transport layer and charge generation layer of Example 5 were sequentially laminated thereon, and an electrophotographic photoreceptor was prepared in the same manner as in Example 5 except for the layer structure, and the charging properties were the same as in Example 5. was measured. However, the charging polarity was set to +. Show the results. V ₀ : +695V V ₁ : +690V E1/2: 1.3lux, sec Example 19 Soluble nylon (6-66-610-
A 5% methanol solution of 12 quaternary nylon copolymer) was applied to form an undercoat layer with a dry thickness of 0.5 μm. Next, 5 g of a pigment having the following structural formula was dispersed in 95 ml of tetrahydrofuran using a sand mill disperser for 20 hours. Next, 5 g of compound example (20) and bisphenol Z type polycarbonate (viscosity average molecular weight 30,000) 10
g dissolved in 30 ml of chlorobenzene was added to the previously prepared dispersion, and the mixture was further dispersed in a sand mill for 2 hours. This dispersion was applied onto the previously formed subbing layer using a Mayer bar so that the film thickness after drying would be 20 μm, and then dried. The electrophotographic properties of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. Show the results. V ₀ :-685V V ₁ :-665V E1/2 : 2.3 lux, sec [Effects of the invention] The electrophotographic photoreceptor containing the specific sulfide compound of the present invention has high sensitivity and continuous It is an electrophotographic photoreceptor with particularly excellent durability because there is little variation in bright area potential and dark area potential during image formation.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer laminated on a conductive support, wherein the photosensitive layer contains a compound represented by the following general formula (). In the formula, R ₁ and R ₂ represent an alkyl group, an aryl group, or an aralkyl group that may have a substituent, and may be the same or different. _R3 represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a _-SR7 group ( _R7 is an alkyl group, an aryl group, or an aralkyl group) which may have a substituent. R ₄ , R ₅ and R ₆ are hydrogen atoms, alkyl groups that may have substituents, aryl groups, aralkyl groups,
It represents a halogen atom or a _-SR7 group, and may be the same or different. However, when R ₁ and R ₂ have a substituent, at least one of R ₃ , R ₄ , R ₅ , and R ₆ is a -SR ₇ group, and two or more -SR ₇ groups In this case, R ₇ need not be the same. X represents an ethylene group, a vinylene group, an oxygen atom, an amino group (= _NR8 ) or a sulfur atom, and _R8 represents an alkyl group, an aryl group or an aralkyl group.