JPH0253067A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve sensitivity and characteristics by incorporating a specific isopyrazole compd. into a photosensitive layer. CONSTITUTION:The isopyrazole compd. expressed by formula I is incorporated into the photosensitive layer. In formula I, Ar denotes an arom. group or heterocyclic group; R1, R2 denote a hydrogen atom, alkyl group, aralkyl group, arom. group or heterocyclic group; R3 denotes a hydrogen atom, alkyl group, aralkyl group or arom. group; R4, R5 denote a hydrogen atom, alkyl group, aralkyl group, arom. group or heterocyclic group. The electrophotographic sensitive body which has the high sensitivity, decreases the fluctuation in the bright part potential and dark part potential at the time of continuous image formation by repetitive electrostatic exposing and has excellent durability is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electrophotographic photoreceptors, and more particularly to electrophotographic photoreceptors containing low molecular weight organic photoconductors that provide 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 and
This is because they are inferior to inorganic photoconductive materials in terms of durability and stability against environmental changes.

Also, hydrazone compounds disclosed in U.S. Pat. No. 4,150,987, triarylvirazoline compounds disclosed in U.S. Pat. No. 3,837,851, etc.,
Low-molecular organic photoconductors such as 9-styrylanthracene compounds described in JP-A-94828 and JP-A-51-94829 have been proposed. These low-molecular-weight organic photoconductors have been able to overcome the film-forming problems that had been a problem in the field of organic photoconductive polymers by appropriately selecting the binder used, but the sensitivity It cannot be said that it is sufficient in this respect.

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. 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 an electrophotographic photoreceptor is disclosed in, for example, US Pat. No. 383
It is disclosed in the specification of No. 7851 and the specification of No. 3871882.

However, electrophotographic photoreceptors that use conventional low-molecular organic photoconductors in the charge transport layer do not necessarily have sufficient sensitivity and characteristics, and when repeatedly charged and exposed, the bright area potential and dark area potential change. There are areas that need improvement.

[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 is an electrophotographic photoreceptor having a photosensitive layer laminated on a conductive support, characterized in that the photosensitive layer contains an impyrazole compound represented by the following general formula (I). It consists of an electrophotographic photoreceptor.

In the formula, Ar represents an aromatic ring group or a heterocyclic group.

R1 and R2 represent a hydrogen atom, an alkyl group, an aralkyl group, an aromatic ring group, or a heterocyclic group, provided that R1 and R2 may jointly form a ring, and when R1 and R2 are hydrogen atoms at the same time, R3 represents a hydrogen atom, an alkyl group, an aralkyl group, or an aromatic ring group, and R4 and R5 represent a hydrogen atom, an alkyl group, an aralkyl group. Indicates an aromatic ring group or a heterocyclic group.

Further, the aromatic ring group, heterocyclic group, alkyl group, and aralkyl group of Ar and R1 to R5 may have a substituent.

Specifically, in Ar, aromatic ring groups include phenyl, naphthyl, anthracene, etc., heterocyclic groups include pyridyl, thienyl, quinolyl, etc., and R,
In -R5, the alkyl group is methyl, ethyl,
Examples include groups such as propyl, aralkyl groups such as benzyl and phenethyl, aromatic ring groups such as phenyl and naphthyl, heterocyclic groups such as pyridyl and quinolyl, and aromatic ring groups represented by Ar and R1-R5. , heterocyclic groups, alkyl groups, and aralkyl groups that may have substituents include alkyl groups such as methyl, ethyl, and propyl;
Flukoxy groups such as methoxy and ethoxy, chlorine, bromine,
Examples include halogen atoms such as iodine, substituted amino groups such as dimethylamino, diethylamino, diphenylamino, and nitro groups.

Representative examples of the impyrazole compound represented by general formula (I) are listed below.

Compound Example (I) Compound Example (2) Compound Example (3) Compound Example (4) Compound Example (5) Compound Example Compound Example Compound Example Compound Example (I3) Compound Example (I Compound Example (I5) Compound Example (I6) Compound Example (9) Compound Example (l O) Compound Example (I1) Compound Example (I2) Compound Example (I7) Compound Example (I8) Compound Example (I Compound Example (20) Compound Example (21) Compound Example (22) CQ Compound Example (24) Compound Example (25) H3 Compound Example (31) Compound Example (32) Compound Example (33) Compound Example (34) Compound Example (26) Compound Example (27) Compound Example (28) Compound Example ( 29) Compound Example (30) Compound Example (35) Compound Example (36) Compound Example (37) f C Compound Example (38) (0.08 mol) was added to 80 m of ethanol, Compound Example (39) Compound Example (40) [Synthesis Example] Synthesis of Compound Example (4) 9.5 g (0
After heating and refluxing 4 mu of hydrazine hydrate for 3 hours, the reaction solution was allowed to cool, and the precipitate was filtered with suction. After washing the obtained crude crystals with ethanol, methyl ethyl ketone-
The target compound was obtained by recrystallization from an ethanol mixed solvent.

Yield 7.4g, yield 78.8% Elemental analysis calculated value (%) Actual value (%) C82,0281,18 H6,026,06 N 11.96 11.96 For compounds other than 1 synthesis example, Generally synthesized using similar techniques.

In a preferred embodiment of the present invention, the compound represented by the general formula (I) 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 is preferably formed by applying a solution of the compound represented by the general formula (I) and a binder dissolved in an appropriate solvent and drying the solution.

Examples of the binder used here include polyarylate,
Polysulfone, polyamide, acrylic resin, acrylonitrile resin, methacrylic resin, iM-ized hibinyl resin, vinyl acetate resin, phenolic resin, epoxy resin, polyester, alkyd resin.

Examples of polycarbonates, polyurethanes or copolymers 1 include 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, polyvinylanthra7ane, and polyvinylpyrene can also be used.

The blending ratio of this 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 underlying charge generation layer and has a mechanism capable 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. In this case, the charge transport layer may be laminated on the charge generation layer (or a vI layer may be formed below it), but the charge transport layer may be laminated on the charge generation layer. It is desirable to be present.

This charge transport layer has a limit to its ability to transport charge carriers, so it cannot be made thicker than necessary.
The inside of the shell is 5 to 40 μm, but the preferred range is 10 to 40 μm.
It is 30pm.

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 underlying subbing layer. 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, N,N-dimethylacetamide, and dimethylsulfoxide. sulfoxides such as, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate,
Aliphatic halogenated hydrocarbons such as methylene chloride, dichloroethylene, carbon tetrachloride, trichlorethylene, etc., or aromatic compounds such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer bar coating method, a blade coating method, a roller coating method, or a curtain coating method. Drying is preferably carried out by drying to the touch at room temperature and then heating. Drying by heating can be carried out in the shell at a temperature of 30 to 200°C for 5 minutes to 2 hours, either stationary or under ventilation. preferable.

The charge transport layer of the present invention may contain various additives, such as plasticizers such as diphenyl, m-terphenyl, and dibutyl phthalate, silicone oil, grafted silicone polymers, and various fluorocarbons. Examples include surface warming lubricants, dicyanovinyl compounds, potential stabilizers such as carbazole derivatives, and antioxidants such as β-carotene, Ni complexes, and 1,4-diazabicyclo[2,2,2]octane.

The charge generation layer in the present invention includes an inorganic charge generation substance such as selenium, selenium-tellurium, amorphous silicone, etc.
Cationic dyes such as pyrylium dyes, thiapyrylium dyes, azulenium dyes, thiacyanine dyes, and quinocyanine dyes Polycyclic dyes such as squbarium salt dyes, phthalocyanine pigments, anthrone pigments, dibenzpyrenequinone pigments, and pyranthrone pigments Materials selected from organic charge-generating substances such as quinone pigments, indigo pigments, quinacridone pigments, and azo pigments can be used alone or in combination as the vapor deposited layer or coating layer.

Among the above-mentioned charge-generating substances, there are a wide variety of 7zo pigments in particular, and a typical structural example of an especially effective azo pigment will be described below.

The general formula of the azo pigment is shown below as A for the central skeleton and Cp for the coupler part, where n is engineering or 2, and an example of A# is given.

A-%N=N-Op) n As a specific example of A.

(R: hydrogen atom, chlorine atom, methoxy group) A-2-@-
cH■C (R: hydrogen atom, cyano group) (x: oxygen atom, sulfur atom R: hydrogen atom, methyl group, chlorine atom) (X: oxygen atom, sulfur!52 atom R,, R2: hydrogen atom, methyl group, chlorine atom) (Rz, R2: hydrogen atom, methyl group, chlorine atom, etc., R3: hydrogen atom, methyl group, -o) (R: hydrogen atom, cyano group) (x: oxygen atom, sulfur atom) ( X: oxygen atom.

sulfur atom) (x: oxygen atom.

sulfur atom) C Yu Hs 1@-c)l-tn-cH-@- :Oxygen atom, sulfur atom) (R: hydrogen atom.

methyl group) (Xs÷ (X d -CHL.

Oxygen atom, sulfur atom, ~SO,) (R: hydrogen atom, methyl group) Specific examples of Cp include 144B) (X: oxygen atom, sulfur atom) (R: hydrogen atom, halogen atom, alkoxy group, Alkyl group, nitro group, etc. n: 1 or 2) (R: methyl group, ethyl group.

(R: alkyl group, aryl group, etc.) (Rr, R2: hydrogen atom, halogen atom, alkyl group, nitro group, etc.) (R: alkyl group, aryl group, etc.) etc. nil or 2).

The central skeleton A and the coupler Cp form a pigment serving as a charge-generating substance by appropriate combination.

The charge generation layer can be formed by dispersing the charge generation 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. .

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 (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol,
Examples include polyvinylpyrrolidone.

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 indulopanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and 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 Panko compounds such as benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, etc. can be used.

Coating methods include dip coating method, spray coating method, spinner coating method, beat coating method,
This can be carried out using a coating method such as a Mayer bar coating method, a blade coating method, a roller coating method, or a curtain coating method.

Drying is preferably carried out by drying to the touch at room temperature and then heating.
It is preferable to carry out the process at a temperature of 5 minutes to 2 hours at a temperature of 50°C, either stationary or under ventilation.

The charge generation layer contains as much of the organic photoconductor as possible to obtain sufficient absorbance and a thin film layer, e.g. 5 gm, to inject carriers into the charge transport layer during the lifetime of the generated charge carriers. Below, preferably 0.01 to I
A thin film layer having a thickness of ILm is desirable.

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 a support having a conductive Ml calendar, the support itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel/henadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate,
acrylic resin, polyfluoroethylene, etc.), conductive particles (e.g., aluminum powder, titanium oxide, tin oxide, zinc oxide, carbon black, silver particles, etc.) are coated on the plastic or the aforementioned conductive support together with a suitable binder. The support may be a support made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, or the like.

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

The subbing layer can be formed 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. .

The thickness of the subbing layer is 0.1 to 5 pm, preferably 0.5 to 3 pm.
The ending m is appropriate.

When using a photoreceptor having 811 layers of a conductive support, a charge generation layer, and a charge transport layer in this order, the charge transport compound in the present invention has hole transport properties, so it is necessary to charge the surface of the charge transport layer negatively. When exposed to light after being charged, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, resulting in attenuation of the surface potential and the difference between the exposed area and the unexposed area. An electrostatic contrast occurs between them.

During development, it is necessary to use positively charged toner.

In another specific example of the present invention, the above-mentioned azo pigment or the biryllium dyes, thiapyrylium dyes, selenapyrylium dyes, and benzene dyes disclosed in U.S. Pat. biryllium dye, hengethia biryllium dye,
Photoconductive pigments and dyes such as naphthopyryllium dyes and naphthothiapyrylium dyes can also be used as sensitizers.

In another specific example, a eutectic complex of a biryllium dye and an electrically insulating polymer having a fullkylidene diarylene moiety, such as disclosed in US Pat. No. 3,684,502, can be used as a sensitizer. This eutectic complex is, for example, 4-[4-bis(2-chloroethyl)ami/phenyl]
-2,6-Cyphenylthiapyrylium perchlorate and poly(4,4'-isopropylidene diphenylene carbonate) are mixed in a halogenated hydrocarbon solvent such as dichloromethane, chloroform, carbon tetrachloride, l.

1-dichloroethane, 1,2-dichloroethane.

1.1. After dissolving in 2-trichloroethane, chlorobenzenebromobenzene, 12-dichlorobenzene, etc.
A particulate eutectic complex is obtained by adding a nonpolar solvent such as hexane, octane, decane, 2,2,4-trimethylbenzene, ligroin, etc. to this.

The electrophotographic photoreceptor in this specific example includes a styrene-butadiene copolymer and a silicone resin.

Vinyl resin, vinylidene chloride-7-crylonitrile copolymer, styrene-7-crylonitrile copolymer, vinyl acetate-vinyl chloride copolymer polyvinyl petyral, 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 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 performing edge-reverse charging and exposure.

〔Example〕

Example 1 5 g of a disazo pigment represented by the following structural formula was mixed with butyral resin (
butyralization degree 63 mol%) 2g cyclohexanone 1
A coating solution was prepared by dispersing in a sand mill for 24 hours with a solution dissolved in 00 mJL.

Apply this coating solution on an aluminum sheet to a dry film thickness of 0.2 g.
A charge generation layer was formed by coating the sample with a Maya bar so as to have a thickness of m.

Next, log of Compound Example (4) as a charge transport material and log 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.

A charge transport layer having a dry thickness of 20 pm was formed to produce an electrophotographic photoreceptor.

The thus prepared electrophotographic photoreceptor was statically charged with corona at 5 KV using an electrostatic copying paper tester Model 1-3P-428 manufactured by Kawaguchi Electric, 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 (■0) and the exposure amount (El/2) required to attenuate the potential (Vl) to 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 used as a PPC copy NP-352'5 (made by Canon ■).
7) Paste it on the photosensitive drum cylinder and use the same machine for 5,
000 copies were made, and fluctuations in the bright area potential (VL) and the dark area potential (Vo) were measured at the initial stage and after 5,000 copies were made.

tt8, initial VD and vL are each h-700V.

It was set to 200v.

For comparison, a similar electrophotographic photoreceptor was prepared using a compound having the structure shown below in place of the charge transport material used in Example 1 as a charge transport material, and the electrophotographic properties were similarly measured.

Show the results.

Example 1 -697 -690 2.2 Comparative example -
699-6884, 1 (l 9), (20), (25), (28), (
31), (33), (36), and (40), and
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that a pigment having the following structural formula was used as a charge generating substance.

v 5 v Example I Vo -700-69lVL -
200-212 Comparative Example Vo -700-67O VL -200-289 As is clear from the above results, when the charge transport material specified in the present invention is used, it has good sensitivity and the potential fluctuation over time is It turns out that there are few.

Examples 2 to 15 In each of these Examples, the charge transport compound example (4) used in Example 1 was replaced with compound example (2).

The electrophotographic properties of each photoreceptor (5), (8), (I1), (I4), and (I8) were measured in the same manner as in Example 1. Show the results.

(l 1) (I4 3.6 2, 7 2.9 2.7 3, 0 initial 1.8 1.9 1.7 1.9 1, 8 2, 7 2.8 3, 7 5,000 pieces After durability 12 700・200 691
213 Example 16 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% aqueous ammonia, 222 m of water) was coated on an aluminum cylinder by a blade coating method to form a subbing layer with a dry film thickness of 17 zm.

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 formed undercoat layer using a blade coating method, and the dry film thickness was 0.15 g.
A charge generation layer of m was formed.

Next, 10 g of compound example (I6) and 70 g of polymethyl methacrylate (average molecular weight 50,000) log of chlorobenzene were added.
g and applied by blade coating onto the previously formed charge generation layer to form a charge transport layer with a dry film thickness of 19 μm.

A corona discharge of 13 KV was applied to the electrophotographic photoreceptor thus prepared. The surface potential at this time was measured (initial potential Vo), and the surface potential after this photoreceptor was left in a dark place for 1 second was measured.

The sensitivity is the exposure 1 (El/2, microjoule/cm2) required to attenuate the potential v1 after dark decay to 172.
The evaluation was made by setting Jilt.

At this time, the light source was a gallium/aluminum/propylene ternary semiconductor laser (output: 5 mw, oscillation wavelength: 780 nm).
m) was used. Show the results.

vo knee 701V vl knee 690Vel
/2: 2.22 Icology Unit / Cm2 Next, a laser beam printer (manufactured by Canon ■,
An actual image forming test was carried out by setting the above photoconductor in place of the photoconductor of LBP-CX (LBP-CX).

The conditions were: surface potential knee 700 V after negative charging, surface potential knee 150 V after image exposure (exposure amount 2.0 microjoules/cm2), transfer potential: +7°OV, developer polarity: negative polarity, process speed. : 50mm/see, development conditions (development bias) = 450■, image exposure scanning method: image ski - +7, -th order pre-charging exposure +50uux, se
Red full exposure 1 image formation of e was carried out by line scanning a laser beam in accordance with character signals and image signals, and good prints were obtained for both characters and images. Furthermore, when images were printed for consecutive h'l 3 and OO0 sheets, stable and good prints were obtained from the initial stage up to 3,000 sheets.

Example 17 3 g of 4-(4-dimethylaminophenyl)-2,6-siphenylthiapyrylium verchlorate and compound example (
5 g of I2) was mixed with a 100 mM solution of polyester (Polyester Athesive 49000, manufactured by DuPont) in toluene (501 parts by weight) and dioxane (50 parts by weight) and dispersed in a ball mill for 6 hours. This dispersion was applied onto an aluminum sheet using a Mayer par so that the film thickness after dry explosion was 15 gm.

The electrophotographic properties of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1. Show the results.

VO・-697V Vl knee 686V): 1/2
: 3.6 Qux, see -1 VD Knee 700V VL Knee 201V Kageri Kyuuki VD Knee 688V VL : 215V Example 18 4-(4-dimethylaminophenyl)-2,6 diphenylthiapyrylium park Loreto 3g and poly(4,4'
- Thoroughly dissolve 3 g of (impropylidene diphenylene carbonate) in 200 ml of dichloromethane, and then
7100m was added to precipitate the eutectic complex. After filtering this precipitate, dichloromethane was added to redissolve it, and then 100 mM of n-hexane was added to this solution to obtain a precipitate of a eutectic complex.

5 g of this eutectic complex was added to a 95+nJ1 methanol solution containing 2 g of polyvinyl butyral, and dispersed using a ball mill disperser for 6 hours. This dispersion was applied onto an aluminum plate containing casein using a Mayer bar so that the film thickness after dry explosion was 0.4 pLm to form a charge generation layer.

Next, a cover layer of a charge transport layer was formed in the same manner as in Example 1 except that Compound Example (9) 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, knee 702V Vl knee 690Vel/2
: 3, 2Qux, sec Tsutomu VD Knee 700V VL: 20
0V Dango” Ohanji (to VD Knee 692V VL Knee 219V
Example 19 An ammonia aqueous solution of casein (described above) was coated on an aluminum plate using a Mayer bar to form an undercoat layer with a dry film thickness of IgmO. The charge transport layer and charge generation layer of Example 8 were sequentially laminated thereon, and an electrophotographic photoreceptor was prepared in the same manner as in Example 8, except that the single layer structure was different, and the charging properties were the same as in Example 8. was measured. However, the charging polarity was set to +. Show the results.

vo: +680V vl: +671VEl/
2:3.7 sentences ux, see Example 20 Soluble nylon (6-66-610-12
Apply a 5% solution of metatsuru (quaternary nylon copolymer),
A subbing layer having a dry film thickness of 0.5 #Lm was formed.

Next, 5 g of the pigment having the following structural formula was added to 95 g of tetrahydrofuran.
The mixture was dispersed in a sand mill for 200 hours using a sand mill disperser.

Next, a solution prepared by dissolving 5 g of Compound Example (32) and log bisphenol Z type polycarbonate (viscosity average molecular weight 30,000) in 30 m of chlorobenzene was added to the dispersion prepared earlier, 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 gm, 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.

vo knee 699V V, knee 683Vel/2
: 3.71 ux, sec [Effects of the Invention] The electrophotographic photoreceptor containing the specific impyrazole compound of the present invention has high sensitivity, and also has a high sensitivity between bright area potential and dark area potential during continuous image formation by repeated band TL exposure. It is an electrophotographic photoreceptor with excellent durability and little fluctuation.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer laminated on a conductive support, wherein the photosensitive layer contains an impyrazole compound represented by the following general formula (I). body. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) In the formula, Ar represents an aromatic ring group or a heterocyclic group, and R_1 and R_2 represent a hydrogen atom, an alkyl group, an aralkyl group, an aromatic ring group or a heterocyclic group. , However, R_1 and R_2 may jointly form a ring, except when R_1 and R_2 are hydrogen atoms at the same time, R_3 represents a hydrogen atom, an alkyl group, an aralkyl group, or an aromatic ring group, and R_4 and R_5 represents a hydrogen atom, an alkyl group, an aralkyl group, an aromatic ring group or a heterocyclic group. Further, the aromatic ring group, heterocyclic group, alkyl group, and aralkyl group of Ar and R_1 to R_5 may have a substituent.