JPH03132762A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having sufficiently high sensitivity and flatness of spectral sensitivity even in the wavelength region of laser diode beams by using a specified azo pigment. CONSTITUTION:A photosensitive layer formed on a conductive substrate contains the azo pigment represented by general formula I in which each of Ar1 and Ar2 is an optionally substituted aromatic or heterocyclic group. The layer containing this pigment exhibits photoconductivity and it can be used for the photosensitive layer of the electrophotographic sensitive body. It is preferred to us, as the form of the photosensitive layer, the functionally separated type photosensitive layer formed by laminating an electric charge generating layer containing the pigment and a charge transfer layer containing a charge transfer material, thus permitting the obtained electrophotographic sensitive body high in sensitivity and flat in spectral sensitivity in the wavelength region of the laser diode beams, stable in image characteristics in an electrophotographic process, and superior in potential stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing an azo pigment having a specific structure in a photosensitive layer.

[Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been widely known.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed.

For example, organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene; low-molecular organic photoconductive polymers such as carbazole-based compounds, anthracene-based compounds, pyrazoline-based compounds, oxadiazole-based compounds, hydrazone-based compounds, and polyarylalkane-based compounds; Organic pigments and dyes such as conductors, phthalocyanine pigments, azo pigments, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are known.

In particular, organic pigments and dyes with photoconductive properties are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded, making it possible to use a large number of photoconductive materials. Conductive organic pigments and dyes have been proposed.

For example, U.S. Pat. No. 4,123,270, U.S. Pat. No. 4,247,614, U.S. Pat. No. 4,251,613, U.S. Pat. No. 4,251,614, U.S. Pat. No. 4268596, U.S. Patent No. 4278747, U.S. Patent No. 4293628
Electrophotographic photoreceptors are known that use an azo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer, as disclosed in the above specification.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, so it is possible to provide an electrophotographic photoreceptor with extremely high productivity and low cost. This electrophotographic photoreceptor has the advantage of being able to freely control the sensitive wavelength range by selection, and improvements have been made in terms of sensitivity and durability, and many of them have come into practical use.

In addition, in recent years, as electrophotographic printers have become popular for outputting microcomputers and word processors, long wavelength light sources such as LEDs and laser diodes have come into use, and these light sources also There is a need for an electrophotographic photoreceptor that can be used.

In particular, when a laser diode is used as a light source, the oscillation wavelength range of the laser diode changes due to individual differences in the laser diode, operating temperature, and temperature rise due to oscillation. It is required to have flat spectral sensitivity.

Especially in printers and color printers where gradation is important, if the spectral sensitivity is not flat, it is necessary to sort the laser diode and use a laser temperature controller to suppress changes in the laser diode's oscillation wavelength. However, there is a drawback that the cost of these printers increases.

For this reason as well, flat spectral sensitivity is required.

As for the flatness of the spectral sensitivity, it is necessary that the change in sensitivity from 760 nm, which is the center of the oscillation wavelength range of the laser diode, to 800 nm is within 0 to 15%, and preferably within 0 to 103%.

As a technology for increasing the wavelength of azo pigments that corresponds to the oscillation wavelength range of such laser diodes, Japanese Patent Application Laid-Open No. 63-2
64762 reports the use of a pigment having a specific coupler component, but the pigment described here has a minimum change in spectral sensitivity of 25% in the range of 760 to 800 nm, which is still not sufficient. , there was room for improvement.

In order to solve the above problems, as a result of intensive research on azo pigments, we were able to achieve sufficiently high sensitivity and flatness of spectral sensitivity in the long wavelength range in azo pigments with a specific structure.

C Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and flatness of spectral sensitivity sufficient even in the laser diode oscillation wavelength range.

[Means and effects for solving the problems] The present invention comprises an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by the following general formula (1) on a conductive support. Ru.

General formula % Formula % (1) In the formula, Ar1 and Ar2 represent an aromatic ring group or a heterocyclic group which may have a substituent which may be bonded via a bonding group, R1 and R2 are hydrogen atoms, Halogen atoms, nitro groups, cyano groups, trifluoromethyl groups, or alkyl groups that may have substituents, alkoxy groups, aralkyl groups,
Indicates an aryl group, a heterocyclic group or an amino group, R3,R
4, R5 and R6 represent a hydrogen atom or a halogen atom, provided that R3, R4, R5 and R6 are not hydrogen atoms at the same time, and R3, R4, R4 and R5, R
5 and R6 may form a fused aromatic ring together with a part of the carbazole ring, x represents an oxygen atom or a sulfur atom, and n
is an integer from 1 to 3, and CPI and CF2 may be the same or different.

Specifically, Arl and Ar2 are aromatic hydrocarbon groups such as benzene, naphthalene, fluorene, phenanthrene, anthracene, and pyrene, furan, thiophene, pyridine, indole, benzothiazole, carbazole,
Aromatic heterocyclic groups such as acridone, dibenzothiophene, benzoxazole, benzotriazole, oxadiazole, thiazole, etc., and those in which the above aromatic rings are bonded directly or with an aromatic group or a non-aromatic group, such as triphenylamine. , diphenylamine N-methyldiphenylamine, biphenyl, terphenyl, binaphthyl, fluorenone, phenanthrenequinone, anthraquinone, benzanthrone, diphenyloxadiazole, phenylbenzoxazole, diphenylmethane, diphenylsulfone, diphenyl ether, benzophenone, stilbene, distyrylbenzene , tetraphenyl-p-phenylenediamine, tetraphenylbenzidine, and the like.

Examples of substituents that Ar1 and Ar2 may have include alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy, ethoxy, and propoxy; halogen atoms such as fluorine, chlorine, and bromine; group, cyano group, etc.

In R1 and R2, halogen atoms include fluorine, chlorine, and bromine atoms, alkyl groups include methyl, ethyl, and propyl, alkoxy groups include methoxy, ethoxy, and propoxy, and aralkyl groups include benzyl, Groups such as phenethyl; aryl groups include phenyl, naphthyl, anthryl, and fluorenyl; heterocyclic groups include pyridyl, quinolyl, furyl, and thienyl; substituted amine groups include dimethylamino, diethylamino, and pyrrolidinodiphenylamino. Examples include groups such as.

Examples of substituents on the alkyl group, alkoxy group, aralkyl group, aryl group, and heterocyclic group include alkyl groups such as methyl, ethyl, and propyl, alkoxy groups such as methoxy, ethoxy, and propoxy, fluorine atoms,
Examples include halogen atoms such as chlorine atoms and bromine atoms, nitro groups, and cyano groups.

In R3, R4, R5 and R6, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and the like.

Representative examples of azo pigments used in the present invention are listed below.

Exemplary pigment (1) CP 1- N -N-o-N = N +N = N
-CP, LC example pigment (2) Cpl -N-N-@-NmN-4ntN-Cp example pigment (3) ) Exemplary Pigment (5) Exemplary Pigment (9) Exemplary Pigment (10) Exemplary Pigment (11) Exemplary Pigment (6) Cp□-N-N-45-N-N-(3-N-N-Cp Exemplary pigment, (7) U) -s-N combined N Tomi N-cp Yu H3 C11! Exemplary pigment (18) c p , -N -N-@-N -N-@-N -N combination N -N -cpz Exemplary pigment (1 6) Exemplary pigment (19) Exemplary pigment (22) cpl-N =NshaN-NshaN-N-@-N-N-Cp.

Exemplary Pigment (20) Hiss Op, -N-N-@-N-? t-@-N-N-@-N-
N-cp.

Exemplary Pigment (23) Exemplary Pigment (21) CPx -N-N+N-NnN=N&N "N-CP
Z Exemplary Pigment (24) CPl Op2: Exemplified Pigment (25) Shimata Exemplified Pigment (26) Exemplified Pigment (27) Exemplified Pigment (30) cpt, CP2: Exemplified Pigment (31) C Exemplified Pigment (32) cpt, CP2 : 6-length Exemplary Pigment (28) Exemplary Pigment (29) Op, -N-N☆N-Ni 〒N-N Combined N-N-111:
pYu Exemplary Pigment (34) cp□-N-N%N-N-@-@-N-N-@)-@)
-N-N-CP yo CPI, CP2: CX Exemplary pigment (36) (J Exemplary pigment (37) cp
-cp.

Exemplary Pigment (40) Exemplary Pigment (38) CP 1- N = N+ N -N JΣN-N3 TON Cp U CPI, cpz: 1 The azo pigment used in the present invention is obtained by converting the corresponding diamine into tetrazotide by a conventional method. After coupling with a coupler in an aqueous system in the presence of an alkali, or converting the tetrazonium salt into a borofluoride salt or zinc chloride double salt, acetic acid is added in an organic solvent such as N,N-dimethylformamide or dimethyl sulfoxide. It can be easily synthesized by coupling with a coupler in the presence of a base such as soda, triethylamine, or N-methylmorpholine.

Synthesis Example (Synthesis of Exemplary Pigment (1)) 4.4'-diaminobenzene6.
37g (0,030mol), concentrated hydrochloric acid 13.24ml
(0,150 mol), add 102 m of water and stir.
After cooling to °C, 4.35 g of sodium nitrite (0,
A solution obtained by dissolving 0630 mol) in 13 mL of water was added dropwise over 5 minutes, then the solution temperature was maintained at 4 to 7° C., stirred for 30 minutes, treated with carbon, and then filtered.

In this filtrate, 5 g (0.09
A solution obtained by dissolving 6 mol) of 90 mM in water was added dropwise under stirring, and the precipitated borofluoride salt was collected by filtration, washed with cold water, washed with 5 acetonitrile, and dried under reduced pressure at room temperature.

Yield: 8.49 g, Yield: 83% Next, in a 1 fL beaker, N,N-dimethylformamide (
500 mJl of DMF) was added to dissolve 6.76 g (0,020 mol), and then 5.1 g (0,050 mol) of triethylamine was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was collected by filtration. , DM
After washing with F 4 times and water 3 times, it was freeze-dried.

Yield 18.28g, yield 79% Elemental analysis calculated value (%) Actual value (%) C65,1065,19 H3,593,57 N 15.71 15.72 Contains an azo pigment represented by general formula (1) The coating exhibits photoconductivity and therefore can be used in the photosensitive layer of the underlying electrophotographic photoreceptor.

The electrophotographic photoreceptor of the present invention has the general formula (
It has a photosensitive layer containing the azo pigment shown in 1).

The form of the photosensitive layer may be any known form, but it is preferable that the photosensitive layer containing the azo pigment represented by the general formula (1) is used as a charge generation layer, and a charge transport layer containing a charge transport substance is added thereto. Laminated functionally separated photosensitive layers are particularly preferred.

The charge generation layer can be formed by coating a coating solution in which the above-mentioned azo pigment is dispersed together with a binder resin in a suitable solvent on a conductive support by a known method, and the film thickness thereof is, for example, 5 pm. Below, preferably 0.1
A thin film layer of ~1.3 pm is desirable.

The binder resin used in this case is selected from a wide range of insulating resins or organic photoconductive polymers, including polyvinyl butyral, polyvinylbenzal, polyarylate, polycarbonate, polyester, phenoxy resin, cellulose resin, acrylic resin, polyurethane. etc., and the amount used is preferably 80% in terms of content in the charge generation layer.
It is not more than 55% by weight, preferably not more than 55% by weight.

The solvent used is preferably selected from those that dissolve the resin described above but do not dissolve the charge transport layer or undercoat layer described later.

Specifically, ethers such as tetrahydrofuran and 1,4-dioxane, ketones such as cyclohexanone and methyl ethyl ketone, amides such as N,N-dimethylformamide, esters such as methyl acetate and ethyl acetate, toluene, xylene, Examples include aromatics such as chlorobenzene, alcohols such as methanol, ethanol, and 2-propanol, and aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichlorethylene.

The charge transport layer is laminated above or below the charge generation layer, and has the function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them.

The charge transport layer is formed by dissolving a charge transport material in a solvent together with an appropriate binder resin as necessary and coating the layer, and the film thickness is generally 5 to 40 pm, but 1.
5 to 30 gm is preferred.

Charge transporting substances include electron transporting substances and hole transporting substances, and examples of electron transporting substances include 12°4.7-)linitrofluorenone, 2,4,5°7-titranitrofluorenone, chloranil, Examples include electron-withdrawing substances such as tetracyanoquinodimethane and polymerized materials of these electron-withdrawing substances.

Hole-transporting substances include polycyclic aromatic compounds such as pyrene and anthracene, carbazole-based, indole-based, imidazole-based, oxazole-based, thiazole-based, oxadiazole-based, pyrazole-based pyrazoline-based, thiadiazole-based, triazole-based compounds, etc. heterocyclic compound, p-
Hydrazone-based compounds such as diethylaminobenzaldehyde-N,N-diphenylhydrazone, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, α-phenyl-4'-N,N-diphenylaminostilbene, 5-[ 4-(di-P-tolylamino)benzylidene] -5H-dibenzo[a, d] A styryl compound such as cycloheptene, a benzidine compound, a triarylmethane compound, triphenylamine, or a group consisting of these compounds in the main chain Alternatively, polymers having side chains (eg, poly-N-vinylcarbazole, polyvinylanthracene, etc.) can be mentioned.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used.

Further, these charge transport materials can be used alone or in combination of two or more.

When the charge transport material does not have film-forming properties, a suitable binder can be used. Specifically, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyacrylamide, polyamide, and chlorinated rubber, or organic photoconductive resins such as poly-N-vinylcarbazole and polyvinylanthracene. Polymers and the like can be mentioned.

Examples of the conductive support on which the photosensitive layer is formed include aluminum, aluminum alloy, copper, zinc stainless steel, titanium, nickel, indium, gold, and platinum. In addition, plastics (e.g. polyethylene,
Polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, etc.) or conductive particles (e.g. carbon black, silver particles, etc.) are coated on a plastic or metal substrate together with a suitable binder resin, or conductive particles are coated on a plastic or metal substrate. A support such as paper impregnated can be used.

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

The undercoat layer can be formed of casein, polyvinyl alcohol nitrocellulose, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, or the like.

The thickness of the undercoat layer is 5 pm or less, preferably 065 to 3 V.
Lm is appropriate.

Another specific example of the present invention is an electrophotographic photoreceptor containing an azo pigment represented by formula (1) and a charge transport material in the same layer. At this time, a charge transfer complex consisting of poly-N-vinylcarbazole and trinitrofluorenone can also be used as the charge transport substance.

The electrophotographic photoreceptor of this example can be formed by coating and drying a solution in which the azo pigment and charge transfer complex described above are dispersed in a suitable resin solution.

The pigment used in any electrophotographic photoreceptor is an azo pigment represented by the general formula (1). The crystal form of the azo pigment may be crystalline or amorphous. It is also possible to use a combination of two or more types of azo pigments shown or in combination with a known charge generating substance.

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, LED printers, liquid crystal printers, and laser plate making.

[Example] Examples 1 to 12 5 g of methoxymethylated nylon (average molecular weight 32,000) and 10 g of alcohol-soluble copolymerized nylon (average molecular weight 29,000) were placed on an aluminum support in 95 g of methanol.
A solution dissolved in the above was applied with a Meyer bar to form an undercoat layer having a thickness of 1 lm after drying.

Next, 5 g of exemplified pigment (1) was added to 95 m of cyclohexanone.
2 g of butyral resin (degree of butyralization 63 mol%) for M
was added to the dissolved solution and dispersed in a sand mill for 20 hours.

This dispersion was applied onto the previously formed undercoat layer using a Mayer bar so that the film thickness after drying was 0.2 lm, and dried to form a charge generation layer.

Next, 5 g of a hydrazone compound with the following structural formula and 5 g of polymethyl methacrylate (number average molecular weight: 100,000) were dissolved in 40 mJl of toluene, and this was placed on a Meyer bar so that the dry film thickness was 201 Lm. The electrophotographic photoreceptor of Example 1 was prepared by coating and drying to form a charge transport layer.

Electrophotographic photoreceptors corresponding to Examples 2 to 12 were prepared using the following exemplary pigments in place of exemplary pigment (1) and using the same conditions as in Example 1 except for the following conditions.

The electrophotographic photoreceptor thus prepared was tested using an electrostatic copying paper tester (Kawaguchi Den@Tara M Od 8th sentence 5P-428).
The sample was corona-charged at 15 KV using a vacuum cleaner, held in a dark place for 1 second, and then exposed to light at an illuminance of 10 lux to evaluate charging characteristics.

As for the charging characteristics, the surface potential (vO) and the exposure amount (El/2) required for the surface potential to attenuate to 1/2 after being left in the dark were measured.

Show the results.

Comparative pigment (1) V −V E 1/2! uxe
5ec1 (1) 680 1
．． 72 (2) 690 1.
83 (4) 695 2.0
4 (6) 700 2.15
(to) 705 1.96
(18) 680 1.87
(23) 685 1.78 (2
5) 700 1.99 (32)
705 2.010 (36)
695 2.111 (38)
690 2.212 (40)
700 2.3 Comparative Examples 1 and 2 Electrophotographic photoreceptors corresponding to Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that an azo pigment having the following structural formula was used, and the electrophotographic photoreceptors were prepared in the same manner as in Example 1. The charging characteristics were evaluated. Show the results.

(Comparative Example 1) vo knee 670V El/2: 3.91 ux'sec (Comparative Example 2) Comparative pigment (2) vo knee 665V El/2: 4.5 ux'sec From these results, it can be seen that the electrophotographic photoreceptor of the present invention 11, l,) It can be seen that the deviation is l,% with a sufficient charger and excellent sensitivity.

Examples 13 to 15 Using the electrophotographic photoreceptors prepared in Examples 2.5 and 10, fluctuations in dark area potential and bright area potential during repeated use were measured.

The method is -6.5KV corona charger.

The electrophotographic photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with an exposure optical system, a developing device, a transfer charger, a static elimination exposure optical system, and a cleaner.

This copying machine is configured to produce an image on transfer paper as the cylinder is driven.

Using this copying machine, the initial dark area potential vD and light area potential vL are
were set at around -700V and -200V, respectively, and the amount of variation ΔVD in the dark potential and the amount ΔvL of variation in the bright potential were measured after repeated use 5,000 times. Show the results.

Note that a negative sign in the amount of change in potential represents a decrease in the absolute value of the potential, and a positive sign represents an increase in the absolute value of the potential.

13 2 = lO + 514
5-10
+1015 10 -15
+10 Comparative Examples 3 and 4 The electrophotographic photoreceptors prepared in Comparative Examples 1 and 2 were used in Example 1.
The amount of potential fluctuation during repeated use was measured using the same method as in 3. Show the results.

3 1 -80 +904
2 -85 +75 From the results of Examples 13 to 15 and Comparative Example 3.4, it can be seen that the electrophotographic photoreceptor of the present invention has little potential fluctuation when used for refinishing.

Example 16 A polyvinyl alcohol film having a thickness of 0.5 gm was formed on the aluminum surface of an aluminum vapor-deposited polyethylene terephthalate film.

A pigment dispersion of the exemplary pigment (40) used in Example 12 was applied onto this using a Mayer bar and dried to give a film thickness of 0.2 jA.
A charge generation layer of m was formed.

Next, 5 g of a styryl compound having the following structural formula and 5 g of polyarylate (1/1 polymer of bisphenol A and terephthalic acid) were added to 40 mJl of tetrahydrofuran.
A solution dissolved in the above was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 20 gm.

The charging characteristics and durability characteristics of the electrophotographic photoreceptor thus prepared were evaluated by the same method as in Example and Example 13. Show the results.

vo knee 700V El/2: 2.3fLux*sec ΔVo knee 10V ΔVL: +lOV Example 17 Electrophotographic photoreceptor in which the charge generation layer and charge transport layer of the electrophotographic photoreceptor prepared in Example 10 were applied in the reverse order. was prepared, and the charging characteristics were evaluated in the same manner as in Example 1. however,
The charging was positive.

Show the results.

vo: +705V El/2:3.5Mux e sec Example 18 On the charge generation layer prepared in Example 9, 5 g of 2,4.7-dolinitro-9-fluorenone and poly-4,4°-dioxydiphenyl were added. A coating solution prepared by dissolving 5 g of -2,2-propane carbonate (molecular weight: 300,000.degree.) in 70 ml of chlorobenzene was applied to a dry film thickness of 15 gm and dried to form a charge transport layer.

The charging characteristics of the electrophotographic photoreceptor thus prepared were measured in the same manner as in Example 1.

However, the charging was positive. Show the results.

vo: +680V El/2: 4.51ux*sec Example 19 2.4.7-) 5g of linitrow-9-fluorenone and 5g of poly-N-vinylcarbazole (number average molecular weight: 300,000)
A charge transfer complex was prepared by dissolving the following in 70 ml of tetrahydrofuran.

This charge transfer complex and 1 g of the exemplified pigment (18) were added to a solution in which 5 g of polyester (trade name: Vylon, manufactured by Toyobo Co., Ltd.) was dissolved in 70 mfL of tetrahydrofuran, and dispersed.

This dispersion was applied onto the undercoat layer formed in the same manner as in Example 1, and dried to form a photosensitive layer with a thickness of 16 square meters.

The electrophotographic photoreceptor thus produced was evaluated in the same manner as in Example 1. The charging was positive.

Show the results.

vo:+690V El/2:4.51ux・Sec Examples 20 to 25 The electrophotographic photoreceptor prepared in Example 1.3.6.8.10.12 was heated using a 780 nm semiconductor laser and its scanning unit/ ) was replaced with a tungsten light source and an electrostatic copying paper tester (Model 5 manufactured by Kawaguchi Electric Co., Ltd.) was used.
Static method using P-428 (7) modified aircraft)
The sample was corona charged at 5.5 KV, held in a dark place for 1 second, and then exposed to laser light to evaluate charging characteristics.

The charging characteristics include the surface potential (Vo) and the amount of light exposure (El
/2) was measured. Show the results.

20 1 680 2
．． 221 3 700
2.322 6 690
2.023 8 685
2.424 10 680
2.325 12 690
2.5 Comparative Examples 5 and 6 The charging characteristics of the electrophotographic photoreceptors used in Comparative Examples 1 and 2 were measured in exactly the same manner as in Example 20. Show the results.

5 1 660 6
．． 06 2 655
6.3 From the results of Examples 20 to 25 and Comparative Examples 5 and 6, it can be seen that the electrophotographic photoreceptors of the present invention all have excellent sensitivity to laser light.

Examples 26 and 27 The spectral sensitivities of the electrophotographic photoreceptors prepared in Examples 3 and 7 were measured using monochromatic light with a light intensity of 1 pLw/Cm2 as the light source of the electrostatic copying paper tester.

The laser oscillation wavelength range of this electrophotographic photoreceptor is 770~
Sensitivity change over 800 nm However, sensitivity E is the surface potential (vO) of -700V, and the exposure amount EΔ500V required for the surface potential to become 1200V (7zJ/cm
2) was measured and calculated. The results will be described later.

Comparative Examples 7 and 8 The charging characteristics of the electrophotographic photoreceptors used in Comparative Examples 1 and 2 were measured in exactly the same manner as in Example 26. The results of calculating ΔE are shown.

26 3 0.9727
7 0.987
1 0.488
2. From the results of 0.52 or higher, it can be seen that the electrophotographic photoreceptor of the present invention exhibits high sensitivity and flat spectral sensitivity in the laser diode oscillation wavelength range.

Example 28 The electrophotographic photoreceptor used in Example 4 was placed in the cylinder of an electrophotographic copying machine equipped with a -5.6 KV corona charger, an exposure optical system, a developer, a transfer charger, a static elimination exposure optical system, and a cleaner. Paste and image characteristics were investigated.

This copying machine is configured to produce an image on transfer paper as the cylinder is driven.

Evaluation of image characteristics using this copying machine was as follows: Humidity: 10% Temperature: 5°C Humidity: 50% Temperature: 18°C Humidity: 80% Temperature: 35°C
Testing was carried out in each of the three environments shown in C. Good images faithful to the original were obtained in all environments. This image showed no bleeding or blurring even after 10,000 sheets of printing, indicating that the single electrophotographic photoreceptor exhibited good characteristics.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention has (1) high sensitivity and flat spectral characteristics in the oscillation wavelength range of a laser diode, (2) exhibits stable image characteristics in the electrophotographic process, and (2) has excellent potential stability. It has excellent and noticeable effects.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula (1) on a conductive support. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) Cp_1, Cp_2: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In the formula, Ar_1 and Ar_2 have substituents that may be bonded via a bonding group. R_1 and R_2 represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, a trifluoromethyl group, or an alkyl group, an alkoxy group, or an aralkyl group that may have a substituent. group, aryl group, heterocyclic group or amino group,
R_3, R_4, R_5 and R_6 represent hydrogen atoms or halogen atoms, provided that R_3, R_4, R_5 and R_6 are not hydrogen atoms at the same time, and
R_3 and R_4, R_4 and R_5, R_5 and R_6 may form a fused aromatic ring together with a part of the carbazole ring, X represents an oxygen atom or a sulfur atom, n is an integer from 1 to 3, and Cp_1 and Cp_2 may be the same or different.