JPH01140162A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to reduce variance of potential during repeating cycles of electric charging and light exposure for a long period by incorporating a specified thioether compound in a photosensitive layer formed on a conductive substrate. CONSTITUTION:The photosensitive layer on the conductive substrate contains at least one of the thioether compounds represented by formula I in which each of R1 and R2 is optionally substituted alkyl, such aralkyl, or such aryl, or each may combine with each other to form a 5- or 6-membered ring; Ar is an optionally substituted divalent aromatic or heterocyclic group; n is 0 or 1; X is S-R3 or O=S-R4; Y is S-R3, optionally substituted alkyl, such aralkyl, or such aryl, or X may combine with Y to form a thioether ring; R3 and R4 are same as R1 and R2, thus permitting sensitivity to be enhanced and potential variance due to repeating cycles of charging and exposure to be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a low molecular weight organic photoconductor that provides improved electrophotographic properties. be.

[Prior art]

Conventionally, various organic photoconductive polymers including polyvinyl carbazole have been proposed as photoconductive materials for use in electrophotographic photoreceptors, but these polymers have poor film formability and poor film formability compared to inorganic photoconductive materials. Although it is excellent in terms of lightness and other aspects, it has been difficult to put it into practical use until now because sufficient film formation properties have not yet been obtained, and sensitivity and
This is because they are inferior to inorganic photoconductive materials in terms of durability and stability against environmental changes. In addition, hydrazone compounds disclosed in US Pat. No. 4,150,987, etc.
Low-molecular organic photoconductive compounds such as triarylpyrazoline compounds described in U.S. Pat. body is proposed. By appropriately selecting the binder used, such low-molecular-weight organic photoconductors can overcome the drawbacks of film-forming properties that had been a problem in the field of organic photoconductive polymers. It cannot be said that the sensitivity is sufficient.

For these reasons, a laminated structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer has been proposed in recent years. Electrophotographic photoreceptors using this laminated structure as a photosensitive layer can now be improved in terms of sensitivity to visible light, charge retention, surface strength, and the like. Such electrophotographic photoreceptors are disclosed, for example, in US Pat. No. 3,837,851 and US Pat. No. 3,871,882.

However, in electrophotographic photoreceptors that use conventional low-molecular-weight organic photoconductors in the charge transport layer, even if their sensitivity and characteristics have reached a practical level, the light area potential decreases when repeatedly charged and exposed. The drawback of large fluctuations in the dark potential has not been sufficiently resolved.

In order to suppress potential fluctuations during repeated use,
For example, JP-A-57-122444, JP-A-62-39
No. 863 discloses a method of mixing an antioxidant in a charge transport layer, and Japanese Patent Application Laid-Open No. 53-26128 discloses a method of mixing an antioxidant into a charge transport layer.
No., JP-A-60-164745, JP-A-62-105
No. 151, etc., describes a method of stabilizing by adding additives. However, the current situation is that these methods are not sufficiently effective, especially when repeatedly used over a long period of time.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an electrophotographic photoreceptor that eliminates the above-mentioned drawbacks or disadvantages.

Another object of the present invention is to provide a novel organic photoconductor.

Another object of the present invention is to provide a novel charge transport material in a laminated photosensitive layer in which a charge generation layer and a charge transport layer are functionally separated.

[Means for solving problems]

The present invention is an electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a thioether compound represented by general formula (I).

general formula In the formula, R1 and R2 are methyl, ethyl, and propyl.

Alkyl groups such as butyl, benzyl, phenethyl.

Aralkyl groups such as naphthylmethyl or phenyl.

Represents an aryl group such as naphthyl, anthryl, and biphenyl. Furthermore, R8 and R2 represent residues necessary to combine to form a 5- to 6-membered ring. Further, the alkyl group, aralkyl group, and aryl group described above may have a substituent. Examples of these substituents include alkyl groups such as methyl, ethyl, propyl and butyl, alkoxy groups such as methoxy, ethoxy, propoxy and butoxy, aralkyl groups such as benzyl, phenethyl and naphthylmethyl, and fluorine.

Halogen atoms such as chlorine, bromine, iodine, methylthio.

Examples include alkylthio groups such as ethylthio and butylthio, aralkylthio groups such as pendylethio and phenethylthio, and arylthio groups such as phenylthio, naphthylthio and biphenylthio.

Ar is phenylene, naphthylene, which may have a substituent,
Arylene groups such as anthrylene, biphenylene, and phenanthrylene, pyridine, and quinoline.

indole, carbazole, thiophene, benzothiophene, acridine, phenothiazine, phenoxazine,
It represents a divalent heterocyclic group derived from phenazine, penzofuran, dibenzofuran, benzoxazole, benzothiazole, benzotriazole, oxadiazole, oxathiadiazole, etc. Examples of these substituents include the same groups as those used for R1 and R2.

Further, n represents an integer of 0 or l. X represents 5-R3 or 5-R4, Y represents 5-R3, an alkyl group, an aralkyl group, or an aryl group that may have a substituent,
Either or both of X and Y has a thioether structure. R3 and R4 have the same meanings as R1 and R2 described above. Specific examples of the alkyl group, aralkyl group, and aryl group that may have substituents are the same as R1 and R2 described above. Furthermore, X and Y represent the necessary residues to combine to form a thioether ring such as I (m is an integer of 2.3 or 4, Z represents a fused aromatic ring).

An electrophotographic photoreceptor containing the novel compound represented by the general formula [I] in its photosensitive layer has high sensitivity, and in particular, potential fluctuations due to repeated charging and exposure over a long period of time are significantly reduced.

The reason for this is not clear, but it is due to ozone and NOx.

It is thought that the d-orbital effect of sulfur atoms works synergistically with environmental deterioration factors such as nitric acid generated inside the copier, thereby preventing the environmental deterioration factors from penetrating into the machine.

However, when one of X and Y is a hydrogen atom, the effect is small.

In particular, the compound of the present invention has a thioether structure in which Ar is phenylene and X and Y are both 5-R3 in the general formula [I], or they are combined to form a thioether ring having two thioether structures. The effect is particularly remarkable when there are two or more thioether structures such as the residues necessary for this.

Representative examples of compounds represented by the general formula CI) are listed below.

＋＋　　　’ C2H5 ■ Next, a synthesis example of the above compound will be shown.

(Synthesis method of Compound Example N1117) 23 g (187 mmof) of trimethyl phosphite and 3.4 g (22 mmol) of trithiocarbonate having the following structure are heated to 55° C. under a nitrogen stream and stirred for 3 hours to react. Next, 35g l of methylene chloride
5. Dissolved P-diphenylaminobenzaldehyde.
4 g (20 mmol) was added and the reaction was continued at 55°C for 15 hours. Next, the reaction solution was once dried to dryness under reduced pressure, and in the case of methylene chloride-petroleum ether, recrystallization was performed twice with a solvent to obtain 5.3 g of the target product. Obtained as yellowish white crystals.

Yield 71%, melting point 131-133″c/elemental analysis value theoretical value measured value cr r3.sg 73.59H5,645,
6O N 3.73 3.76 Compounds other than those on the synthetic side are also synthesized by a general method such as dehydration condensation with a dithioether having an active methylene group.

In a preferred embodiment of the present invention, a compound represented by the above general formula can be used as a charge transport material 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 according to the present invention is preferably formed by applying a solution prepared by dissolving the compound represented by the above general formula and a binder in an appropriate solvent and drying the solution. Examples of the binder used here include polyarylate resin, polysulfone resin, polyamide resin, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester resin, alkyd resin, and polycarbonate. , polyurethane or copolymer resins such as styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer 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 the binder and the charge transport material of the present invention is preferably 10 to 500 parts by weight of the charge transport material per 100 parts by weight of the binder.

The charge transport layer is electrically connected to the charge generation layer 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. ing. At this time, the charge transport layer may be laminated on the charge generation layer, and
Moreover, it may be laminated thereunder. 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 μm to 40 μm, but a preferable range is
is 10 μm to 30 μm.

The organic solvent used when forming such a charge transport layer is
The binder varies depending on the type of binder used, and it is preferable to select one that does not dissolve the charge generation layer or underlying subbing layer. Specific organic solvents include alcohols such as methanol, ethanol, and impropatul, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and N.

Amides such as N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, and methylene chloride. , aliphatic halogenated hydrocarbons such as dichloroethylene, carbon tetrachloride, and trichlorethylene, or aromatics such as benzene, toluene, xylene, monochlorobenzene, and dichlorobenzene.

Coating can be performed using a coating method such as a dip coating method, a spray coating method, a Meyer bar coating method, or a curtain coating method.

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° C. to 200° C. for a period of 5 minutes to 2 hours, either stationary or with ventilation.

The charge transport layer of 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 Examples include complexes, antioxidants such as 1,4-diazabicyclo(2,2,2)octane, and the like.

The charge generation layer used in the present invention is made of inorganic charge generation substances such as selenium, selenium-tellurium, amorphous silicon, biryllium dyes, thiapyrylium dyes, azulenium dyes, thiacyanine dyes, quinocyanine dyes, azulenium dyes, etc. Organic charge generation such as cationic dyes, squbarium salt dyes, phthalocyanine pigments, anthorone pigments, dibenzpyrenequinone pigments, polycyclic quinone pigments such as pyranthrone pigments, indigo pigments, quinacridone pigments, azo pigments, etc. Materials selected from among the substances can be used alone or in combination as a vapor deposited layer or a coating layer.

Among the charge-generating substances used in the present invention, there are a wide variety of azo pigments in particular, and typical structural examples of particularly effective azo pigments are shown below.

The general formula of an azo pigment is as shown below, with the central skeleton being A.

A(-N=N-Cp)n If we express a part of the coupler as Cp (here n=2゜o
r3), first, specific examples of A include the following.

Tatami C2H5 Also, specific examples of Cp include (R: alkyl, aryl, etc.). 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 above-mentioned charge-generating substance in a suitable binder and coating it on a support, or can be obtained by forming a vapor-deposited film using a vacuum evaporation device. Can be done. The binder can be selected from a wide range of insulating resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably, polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate,
Acrylic resin, polyacrylamide resin, polyamide,
Examples include insulating resins such as polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone.

The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less. Examples of organic solvents used during coating include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, and N,N-dimethylformamide.

Amides such as N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, 'dichloroethylene , carbon tetrachloride, aliphatic halogenated hydrocarbons such as trichlorethylene, benzene, toluene,
Aromatics such as xylene, monochlorobenzene, dichlorobenzene, etc. can be used.

The charge generation layer may contain the thioether compound of the present invention.

The charge generation layer contains as much of the organic photoconductor as possible in order to obtain sufficient absorbance and in order to inject carriers into the charge transport layer within the lifetime of the generated charge carriers, a thin film layer, e.g. 5 μm or less, preferably 0.01 μm
Preferably, the thin film layer has a thickness of mm-1a.

q means that most of the incident light is absorbed by the charge generation layer, generating a large number of charge carriers, and that the generated charge carriers are transported without being deactivated by recombination or trapping. This is due to the need to inject into the layer.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive support.

As the conductive support, the support itself is conductive, such as aluminum, aluminum alloy, stainless steel, titanium, nickel, indium, etc. In addition, aluminum, aluminum alloy, indium oxide, tin oxide, etc. can be used. , plastic conductive particles (e.g., aluminum powder, titanium oxide, tin oxide, zinc oxide, carbon black, silver particles, etc.) having a layer formed by vacuum evaporation of indium oxide-tin oxide alloy, etc., in a suitable binder. In addition, plastic or a support coated on the conductive support, a support made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive support and the photosensitive layer.

The subbing layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. Can be formed.

The thickness of the undercoat layer is 0.1 μm to 5 μm, preferably 0.1 μm to 5 μm.
A suitable thickness is 5 μm to 3 μm.

In another specific example of the present invention, the above-mentioned disazo pigment, or pyrylium dyes, thiapyrylium dyes, selenapyrylium dyes, and benzopyrylium dyes disclosed in U.S. Pat. No. 3,554,745, U.S. Pat. Pigments and dyes having photoconductivity such as , penzothiapyrylium dye, naphthopyrylium dye, and naphthothiapyrylium dye 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, can also be used as a sensitizer. This eutectic complex is, for example, 4
-[4-bis-(2-chloroethyl)aminophenyl]
-2,6-Cyphenylthiapyrylium perchlorate and poly(4,4'-isopropylidene diphenylene carbonate) are mixed in a halogenated hydrocarbon solvent (e.g., dichloromethane, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1.2-dichloroethane, 1,1.2-trichloroethane, chlorobenzene, bromobenzene, 1.
2-dichlorobenzene) and then dissolved in a non-polar solvent (e.g. hexane, octane, decane, 2.2.4
-) remethylbenzene, ligroin) as a particulate eutectic complex. The electrophotographic photoreceptor in this specific example includes styrene-butadiene copolymer, silicone resin, 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. can be contained as a binder.

The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser printers, CRT printers,
It can also be widely used in electrophotographic application fields such as electrophotographic plate making systems.

According to the present invention, it is possible to provide an electrophotographic photoreceptor that is highly sensitive and exhibits little potential fluctuation even after repeated charging and exposure over a long period of time.

Hereinafter, the present invention will be explained according to examples.

Example 1 and Comparative Examples 1 and 2 5 g of a disazo pigment represented by the following structural formula, 2 g of butyral resin (degree of butyralization 70 mol%), and 100 mj of cyclohexanone! 24 hours in a sand mill with the solution dissolved in
A coating solution was prepared by dispersing the mixture over time.

This coating solution was applied onto an aluminum sheet using a Mayer bar to a dry film thickness of 0.2 μm to form a charge generation layer.

Next, the above-mentioned exemplary compound k (13)1 is used as a charge transport substance.
0g and polycarbonate resin (average molecular weight 20,000)
10 g of the monochlorobenzene was dissolved in 70 g of monochlorobenzene, and this solution was applied onto the charge generation layer using a Mayer bar to form a charge transport layer having a dry film thickness of 20 ILm, thereby producing a two-layer electrophotographic photoreceptor.

The electrophotographic photoreceptor produced in this way was manufactured by Kawaguchi Electric Co., Ltd.
Using an electrostatic copying paper testing device Model-8P-428, corona charging was carried out statically at 15 KV, and 1
After being held for a second, it was exposed to light at an illuminance of 20fux and the charging characteristics were examined.

The charging characteristics include the surface potential (vo) and the amount of light exposure required to attenuate the potential (vl) when dark decaying for 1 second (
8%) was measured.

Furthermore, in order to measure the fluctuations in bright area potential and dark area potential during repeated use, the photoreceptor prepared in this example was attached to the photosensitive drum cylinder of a PPC copying machine NP-3525 manufactured by Canon Inc. , 50,000 copies were made using the same machine, and changes in bright area potential (VL) and dark area potential (VD) at the initial stage, after 5,000 copies, and after 50,000 copies were measured.

In addition, the initial VD and vL are /r-700V and -200V, respectively.
It was set so that For comparison, similar photoreceptors were manufactured using compounds (A) and (B) represented by the following structural formulas in place of the above-mentioned exemplified compounds as charge transport materials, and measurements were conducted in the same manner.

The results are shown in Table 1.

Table 1 As is clear from Table 1, the photoreceptor using the compound of the present invention is highly sensitive and stable with little potential fluctuation even after a durability test of 50,000 sheets. Incidentally, the photoreceptors of Example 1 and Comparative Examples 1 and 2 were used at 50,000
After the sheet durability, image reproduction was examined using the above-mentioned copying machine NP-3525 under the same conditions as in the initial stage, and although almost no blurring was observed in the Examples, quite severe ground force blur was observed in the Comparative Examples.

Examples 2 to 15 and Comparative Examples 3 to 12 In each of these Examples, Exemplified Compound N was used instead of Exemplified Compound (13) as the charge transport substance used in Example 1.
Q (1) (4) (5) (8) (11) (1
6) (1s) (21) (25) (28) (29
) (34) (35) (38) and a pigment with the following structure as the charge generating substance was used as Example 1.
An electrophotographic photoreceptor was manufactured in the same manner as described above.

The electrophotographic properties of each photoreceptor were measured in the same manner as in Example 1. The results are shown in Table 2 below.

In addition, as comparative examples, photoreceptors manufactured in the same manner using several compounds known as charge transport materials, and photoreceptors manufactured by adding 10% by weight of a known stabilizer to the compound of Comparative Example 2 were also similarly prepared. measurements were carried out. The results are shown in Table 3.

(Incidentally, for Comparative Example 10, V is -680V and VL is -230V at the time of 5000 sheets durability, and Comparative Example 2 with no additives has VD-660V, VL-250VI: Although it is effective compared to 50000 sheets After durability, the potential fluctuations were almost the same.) As is clear from Tables 2 and 3, the compound of the present invention is an excellent photoreceptor with high sensitivity and little potential fluctuation after 50,000 sheets of durability. It can be seen that it gives

Further, in view of the sensitivity and the magnitude of potential fluctuation, especially in the present invention, when Ar is a phenylene group and there are two thioether structures, particularly favorable results are obtained. .2g, 28% ammonia water Ig,
Water (222 mA) was applied using 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 represented by the following structural formula, 5 g of butyral resin (degree of butyralization: 63 mol %), and 200 g of cyclohexanone were dispersed for 48 hours using a ball mill disperser. This dispersion was applied onto the previously prepared undercoat layer using a blade coating method, and the dry film thickness was 0.15 μm.
A charge generation layer of m was formed.

Next, 10 g of the above exemplary compound No. (9), 10 g of polymethyl methacrylate resin (average molecular weight 50,000)
was dissolved in 70 g of monochlorobenzene and applied onto the previously formed charge generation layer by a blade coating method.
A charge transport layer having a dry thickness of 19 μm was formed.

A corona discharge of 15 KV was applied to the photoreceptor thus produced. The surface potential at this time was measured (initial potential Vo).

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 1 second. Sensitivity is defined as the amount of exposure (E'A, μJ/crrr) required to attenuate the potential V after dark decay to A.
) was evaluated by measuring. At this time, a gallium/aluminum/propylene ternary semiconductor laser (output power: 5 mw; oscillation wavelength: 780 nm) was used as a light source. These results were as follows.

Vo: -680V V,: -670V E'4: 1.1 tLJ, 7cm"Next, an 8 laser beam printer (Canon LBP-CX) is a reversal development type electrophotographic printer equipped with the same semiconductor laser as above. The above photoreceptor was replaced with an LBP-CX photoreceptor, and an actual image forming test was conducted.

The conditions are as follows. -Surface potential knee 7 after next charging
00V, surface potential after image exposure; -150V (exposure amount 2.0 μJ/crrr) transfer potential +700V, developer polarity; negative polarity, process speed; 50mm/
sec, development conditions (development bias); -450V, image exposure scan method; image scan, -exposure before next charging;
Full red exposure of 501uX-8eC and image formation were carried out 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 30,000 images were printed continuously, stable and good prints were obtained from the initial stage up to 30,000 sheets.

Example 17 3 g of 4-(4-dimethylaminophenyl)-2,6-cyphenylthiapyrylium perchlorate and 5 g of the above-mentioned exemplified charge transport substance (15) were added to polyester (Polyester Adhesive 49000, manufactured by DuPont) in toluene. (5
0 parts by weight)-dioxane (50 parts by weight) solution 100 m
1 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 18 μm.

Example 1 The electrophotographic characteristics of the photoreceptor produced in this manner are as follows.
It was measured in the same manner as. The results are shown below.

Vo: -680V V,: -670V EV2: 1.4I! uxΦsec Expansion VD: -700V VL: -200V 50000' VD: -665V VL: -245V Example 18 3 g of 4-(4-dimethylaminophenyl)-2,6-cyphenylthiapyrylium verchlorate and poly( 4,4
'-isopropylidene diphenylene carbonate) 3g
200mj of dichloromethane! After sufficiently dissolving the mixture, 100 m Il of toluene was added to precipitate the eutectic complex. After filtering this precipitate, dichloromethane was added to dissolve it again, and then 100 ml of n-hexane was added to this solution.
was added to obtain a precipitate of a eutectic complex.

5 g of this eutectic complex was added to a methanol solution containing 2 g of polyvinyl butyral at 95 mI! In addition, the mixture was dispersed in a ball mill for 6 hours. This dispersion was applied onto an aluminum plate having a casein layer using a Mayer bar so that the film thickness after drying was 0.5 μm to form a charge generation layer.

Next, a cover layer of a charge transport layer was formed on this charge generation layer in exactly the same manner as in Example 1 except that exemplified compound (23) was used.

The electrophotographic properties of the photoreceptor thus produced were measured in the same manner as in Example 1. The results are shown below.

Vo: -700V V□: -690V E'4: 1. ! Jj'uxIIsec first--this VD: -700V VL:, -200V 50 000 mouth 'VD
: -670V VL : -235V [Effects of the Invention] As explained above, the electrophotographic photoreceptor containing the thioether compound of the present invention has high sensitivity, and also has a bright area potential and a low potential during continuous image formation by repeated charging and exposure. It is possible to provide an electrophotographic photoreceptor with excellent durability and small fluctuations in dark area potential.

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive support, the photosensitive layer has the general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼……(I) [In the formula, R_1 and R_2 is an alkyl group, an aralkyl group, an aryl group that may have a substituent, or R_1 and R
Residues necessary for bonding at _2 to form a 5- to 6-membered ring are shown. Ar represents an arylene group or a divalent heterocyclic group which may have a substituent, and n represents an integer of 0 or 1. X represents S-R_3 or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, Y represents S-R_3, an alkyl group, an aralkyl group, or an aryl group that may have a substituent, or X and Y Residues necessary for bonding to form a thioether ring are shown. R_3 and R_4 are synonymous with R_1 and R_2. ] An electrophotographic photoreceptor comprising a thioether compound represented by the following. (2) In the above general formula (I), Ar represents a phenylene group, and X and Y both have a thioether structure represented by S-R_3, or combine to form a thioether ring having two thioether structures. The electrophotographic photoreceptor according to claim 1, which is a residue necessary for