JPH03216661A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a high sensitivity and small residual potential and to improve a charge holding power, durability, etc., by providing a photosensitive layer ocntg. at least one kind of specified asymmetric squarium compds. on a conductive base. CONSTITUTION:The photosensitive layer contg. the asymmetric squarium compd. expressed by formula I is provided on the conductive base. In the formula I, Ar1 and Ar2 vary from each other and either of Ar1 and Ar2 is selected from the groups expressed by formula II and the other is selected from the groups expressed by formula III, etc. In the formula II, R1 to R5 respectively denote a hydrogen atom, halogen atom, etc. In the formula III, R11, R12 respectively denote a hydrogen atom, halogen atom, substd. or unsubstd. alkyl group, etc.; X11 denotes a substd. or unsubstd. aliphat. hydrocarbon ring, substd. or unsubstd. aliphat. heterocycle, etc.; R13, R14 respectively denote a substd. or unsubstd. alkyl group. The electrophotographic sensitive body having the excellent sensitivity, residual potential and charge holding power, etc., and the excellent durability is obtd. in this way.

Description

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

[Conventional Technique'JIii] Conventionally, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide, silicon, etc. have been widely used as electrophotographic photoreceptors. . However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, manufacturing cost, etc. For example, selenium is difficult to manufacture because its performance and characteristics as a photoreceptor deteriorate when it crystallizes due to heat or fingerprint stains. In addition, cadmium sulfide has problems with moisture resistance and durability, and zinc oxide has problems with durability.

In order to overcome these drawbacks of inorganic photoreceptors, research and development have been actively conducted in recent years on organic photoreceptors having photosensitive layers containing various organic photoconductive compounds as main components. For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinyl Rubazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with higher performance by assigning the carrier generation function and the carrier transport function to different substances. Many studies have been conducted on such so-called function-separated type photoreceptors because each material can be selected from a wide range and a photoreceptor having arbitrary performance can be produced relatively easily.

[Problems to be Solved by the Invention] Many compounds have been proposed as carrier-generating substances in the above-mentioned functionally separated electrophotographic photoreceptor. An example of using an inorganic compound as a carrier generating substance is amorphous selenium described in Japanese Patent Publication No. 43-16198, which is used in combination with an organic photoconductive compound. The carrier generation layer crystallizes due to heat, and its properties as a photoreceptor deteriorate.

Furthermore, many electrophotographic photoreceptors using organic dyes or organic pigments as carrier-generating substances have been proposed. Typical examples include bisazos, trisazos, futacyanines,
Pyryliums, squariums, etc. are known.
Phthalocyanines, trisazos, and squariums have been reported to have sensitivity from the visible region to the near-infrared region.

However, the capacitor cyanines have the disadvantage that the spectral sensitivity is biased toward long wavelengths and the reproducibility of red color is poor, and the trisazo compounds do not have excellent electrical properties and sufficient sensitivity.

In addition, although the conventional squarium compounds shown in JP-A No. 49-105536 and others have relatively high sensitivity, they have drawbacks in chargeability, dark decay, etc., and it is difficult to achieve both high sensitivity and low dark decay. not present.

Furthermore, in recent years, Ar laser has been used as a light source for electrophotographic photoreceptors.
Gas lasers such as He-Ne lasers and semiconductor lasers are beginning to be used. These lasers have a characteristic that they can be turned on and off in time series, and are particularly promising as light sources for copying machines with image processing functions, computer output printers, and the like. Among these, semiconductor lasers are attracting attention because their nature does not require electrical signal/optical signal conversion elements such as acoustic engineering elements, and they can be made smaller and lighter.

However, this semiconductor laser has a low output compared to a gas laser, and the oscillation wavelength is also long (approximately 780nl L).
For this reason, many of the conventional electrophotographic photoreceptors have spectral sensitivities on the short wavelength side, and none of them have practically satisfactory sensitivity characteristics.

The present invention has been made to solve the above problems,
The purpose of the present invention is to achieve high sensitivity and low residual potential.
The object of the present invention is to provide an electrophotographic photoreceptor that is excellent in electrophotographic properties such as charge retention and has excellent durability such that these properties do not change even after repeated use.

Another object of the present invention is to provide an electrophotographic photoreceptor containing an asymmetric squarium compound that can effectively act as a carrier-generating substance even in combination with a wide variety of carrier-transporting substances.

Still another object of the present invention is to provide an electrophotographic photoreceptor that is stable against heat and light and has sufficient practical sensitivity even to long wavelength light sources such as semiconductor lasers.

Still other objects of the present invention will become apparent from the description in the specification.

[Means for Solving the Problems] As a result of intensive research to achieve the above object, the present inventors discovered that a specific asymmetric squarium compound can act as an active ingredient of an electrophotographic photoreceptor. , has completed the present invention.

That is, the above object of the present invention is achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing an asymmetric squarium compound represented by the following general formula [I] on a conductive support. Ru.

General formula [I] In the r formula, Ar+ and Arz are different from each other, one of Ar+ and Ar2 is selected from the groups represented by the following general formula [A], and the general formula [A co(in the formula, R1, R2 and R3 are a hydrogen atom, a halogen atom, water [, an alkyl group, a cyano group, a nitro group, an aryl group, -C-X (X is a hydrogen atom, an alkyl group, or a W1-substituted or unsubstituted aO11 ), -0-C-Rs (Rs represents a hydrogen atom or an alkyl group) or a substituted amino group, R4 and R5 are respectively a water atom, a halogen atom, an alkyl group, an alkoxy group, Represents hydroxyl 0 1 group or NHY.Y is 10-R? or -SO2
-R8 (R7 and R8 each represent a hydrogen atom, an alkyl group, or an aryl group.)] And the other of Ar+ and Ar2 is represented by the following general formula [8]
．． [01. [D]. [E]. It is selected from the group represented by [F] or [G].

General formula [B] (wherein R11 and R+2 each represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a hydroxyl group, or 0 11 represents NHY. Y is 10-R7 or -802
-Rll (R7 and R8 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group).X+1 is a substituted or unsubstituted aliphatic hydrocarbon ring, a substituted or Represents an atomic group necessary to form an unsubstituted aliphatic heterocycle, a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocycle. Rl3 and R+4 are each substituted or unsubstituted. Represents a substituted alkyl group, and when these together form a 3- to 7-membered ring represents an alkylene group. It does not represent the atomic group necessary to form a hydrocarbon ring, a substituted or unsubstituted aliphatic heterocycle, a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocycle. R21 and R22 each represent a substituted or unsubstituted alkyl group, and when they jointly form a 3- to 7-membered ring, they represent an alkylene group. ) (In the formula, R3+, R32 and R33 have the same meanings as R++ and R+2 in the general formula [B], respectively.

R34 represents a substituted or unsubstituted alkyl group.

X31 is a carbon atom group necessary to form an at least 6-membered saturated or unsaturated monocyclic hydrocarbon or polycyclic hydrocarbon, or at least 5-membered carbon atom including at least one heteroatom other than the nitrogen atom; Each represents a group of atoms necessary to form a ring. ) General formula [E] <<In the formula, R41 . R42. R43 and R44 are
Each has the same meaning as Rll and R+2 in the above general formula [8], and R4S represents a substituted or non-II substituted alkyl group.

Ar+ represents a substituted or unsubstituted naphthyl group, anthranyl group, fused polycyclic group or heterocyclic group. >> General formula [F] (wherein, Rs+.R52.Rsa and R54 are
Each has the same meaning as R++ and R+2 in the general formula [8], and A'51 and Ar52 each represent a substituted or unsubstituted naphthyl group, anthranyl group, fused polycyclic group, or heterocyclic group. ) General formula [G] (wherein, R6+.R62 and R63 are respectively synonymous with R++ and R12 in the general formula [81], and R64.
Rss, Rss and R67 each represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group. Ar6 represents a substituted or unsubstituted aryl group. >>1 Hereinafter, the asymmetric squarium compound according to the present invention will be specifically explained.

The asymmetric squarium compound according to the present invention has the general formula [
I], one of Ar+ and Ar2 in the general formula [I] is selected from the groups represented by the above-mentioned general formula [A], and the other Ar1 or A'2 is represented by the above-mentioned general formula [81. [C]. [0]. [E], [F] or [G]
selected from the groups represented by

R1 in general formula [A]. The alkyl group represented by R2 or R3 has 1 to 5 carbon atoms or -N-SO
Preferably, those represented by 2R'' are 1R' (where R'.R'' and R1 each represent a hydrogen atom or an alkyl group).

Furthermore, R++ and R12 in general formula [8], general formula [
D] in R31. R32 and R33, general formula [E]
R41. R42, R43 and R44, general formula [
F] Rs+. R52, Rss and R5
4. R61 in general formula [G]. The alkyl group for R62 and R63 is preferably an alkyl group having 1 to 7 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. This alkyl group includes those having a substituent, and typical examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group, and the like.

Specific examples of the alkyl group include a methyl group, an ethyl group, a chloromethyl group, and among these, preferable ones are:
Methyl group, etc.

R1+ and R12 in general formula [8], general formula [0]
R3+, R32 and R33 in formula [E], R4+ in general formula [E]. R42. R43 and R44, general formula [F]
Rs+ in . R52. Rs3 and R54,
R6+ in general formula [G]. Examples of the halogen atom for R62 and R63 include a chlorine atom, a bromine atom, a fluorine atom, and the like.

Furthermore, as the alkoxy group, for example, carbon atoms 1 to 7
are preferable, and specific examples thereof include methoxy and ethoxy groups.

General formula [A]. Y of NHY in [B] represents O 11 -C-R7 or -SO2-Ra, but R7 and R
Examples of the alkyl group represented by 8 include a methyl group, an ethyl group, and a probyl group. Further, examples of the aryl group include a phenyl group and anisoyl group. Examples of the alkyl group for R13 and R++ in general formula [8] include a methyl group, an ethyl group, a buOvir group, a hebutyl group, and the like.

R45 in the general formula [E] represents an alkyl group that may have a substituent, and typical examples of the substituent include an alkyl group, a phenyl group, a hydroxyl group, an alkoxy group, a halogen atom, and the like. Also, Ars in general formula [G]
Examples of the 7-aryl group include substituted or unsubstituted phenyl groups.

Specific examples of the squarium compounds useful in the present invention are shown below, but the squarium compounds of the present invention are not limited thereto.

B-2 B-3 B-4 n 0 B-5 B-10 B-12 0 n B-13 B-14 B-15 B-16 B-17 n n B 18 B-20 B-21 B-22 0 0 C) B-28 B-29 B-30 0 0 O B-31 C-18 D-15 D-16 D-17 D-18 D-19 U 0 D-20 D-25 E-17 U 1 CH 3 E-21 n Hereinafter, Successor F-10 Exemplary Compound G-2 G-3 The asymmetric squarium compound of the present invention represented by the general formula [I] is described, for example, in JP-A No. 62-267753 and S
PSE proceedings p. 19. According to the description in 1989, the synthesis is carried out in four steps as shown in the formula below. O O In the first step, a solvent is added to the acid chloride of formula (A), and then tetraethoxyethylene (B) and Add amine and allow to react. Next, as a second step, after post-treatment, the compound is purified by treatment with aluminum oxide to obtain a compound of formula (C).

In the third step, the compound of formula (C) obtained in the second step is hydrolyzed by heating under reflux in dilute hydrochloric acid to obtain the compound of formula (D).

In the fourth step, the compound of formula CD) obtained and isolated in the third step is refluxed in a solvent or under reduced pressure to obtain Ar2 of formula (E).
-1-1 is reacted to obtain the desired asymmetric squarium compound (F). As the l medium used here, primary or secondary alcohols having 2 to 10 carbon atoms, or azeotropic mixtures of these alcohols and aromatic hydrocarbons such as benzene, toluene, and xylene can be used.

Next, a specific method for synthesizing the asymmetric squarium of the present invention will be described below.

(Synthesis of compound (H)) Penzylchloride compound (G) 180a was converted into n-hexane 2
1, add 205 g of tetraethoxyethylene (B) and 101 g of triethylamine, and stir for about 10 hours. Then, it was treated with 500 g of aluminum oxide to obtain compound (H) 175 (J. Yield: 58%.

(Synthesis of Compound (1)) 1 liter of 20% hydrochloric acid was added to 175G of compound (H), and the mixture was heated under reflux for 5 hours. After post-treatment, 960 OH compound (1) was obtained.

Yield 83%.

(Synthesis of Exemplified Compound 8-2) 1-Hebutanol 5Il and Compound (J) 98G were added to OH compound (1) 96111, and the mixture was stirred and heated under reflux for 2 hours under reduced pressure. Suction filtrate while hot and wash three times with 10 tons of acetone. Dry under reduced pressure to obtain 128% of the target exemplary compound B-2.
I got g. Yield 69%.

Elemental analysis CHN Calculated value (%) 78.13 6.25 7.
29 Actual value (%) 78.09 6.29
7.25 Spectral absorption spectrum (in methylene chloride) λwa
x = 641 nm (in methylene chloride) Infrared absorption spectrum (in KBr) v wax = 1590 cm-' (C = 0
) Melting point (Japanese Pharmacopoeia Melting Point Measurement Method) 236°C The asymmetric squarium compound according to the present invention has excellent photo-S conductivity, and when producing a photoreceptor using it, it is possible to deposit the compound on a conductive support. Although it can be produced by providing a photosensitive layer in which the asymmetric squarium compound of the present invention is dispersed in a binder, it is possible to produce the asymmetric squarium compound of the present invention by utilizing the particularly excellent carrier generation ability of the photoconductivity possessed by the asymmetric squarium compound of the present invention. Particularly excellent results can be obtained when a so-called functionally separated type photoreceptor is constructed by using it as a carrier-generating substance and using it together with a carrier-transporting substance that can effectively act in combination with the carrier-generating substance.

The functionally separated photoreceptor may be of a dispersed type, but it is more preferably a laminated type photoreceptor in which a carrier generation layer containing a carrier generation substance and a carrier transport layer containing a carrier transport substance are laminated.

When the asymmetric squarium compound of the present invention is used as a carrier-generating substance, carrier-transporting substances that can be used in combination with it include electron-accepting substances that easily transport electrons, such as trinito-O fluorenone or tetranitrofluorenone, as well as polystyrene. Polymers having a heterocyclic compound in the side chain such as N-vinyl rubber, triazole derivatives, oxadiazole derivatives, imidazole derivatives, birazoline derivatives, polyarylalkane derivatives, phenylenediamine derivatives, hydrazone derivatives, amine substitution Examples of electron-donating substances that easily transport holes include calgon derivatives, triarylamine conductors, carbazole derivatives, stilbene derivatives, phenothiazine derivatives, azine derivatives, butadiene derivatives, Schiffbase derivatives, polysilane derivatives, and polyaniline derivatives. The carrier transport materials used in the invention are not limited to these.

Various configurations of photoconductors are known, and the photoconductor of the present invention can take any of these configurations.

Usually, the configurations shown in FIGS. 1 to 68 are used. FIG. 1 shows an example of a photoreceptor for negative charging, in which a carrier generation layer 2 containing the above-mentioned asymmetric squarium compound as a main component is placed on a conductive support 1, and a carrier containing a carrier transporting substance as a main component is formed on the carrier generation layer 2. This is the case where the photosensitive layer 4 has the transport layer 3 in a laminated structure.

FIG. 2 shows an example of a photoreceptor for positive charging, in which a carrier generation layer 2 is provided on a carrier transport layer 3.

In this case, in order to protect the carrier generation layer, it is desirable to form an overcoat layer or an intermediate layer on the carrier generation layer.

Various binders can be used for the overcoat layer, but acrylic resins, isocyanate resins, etc. are preferable. Furthermore, tin oxide, titanium oxide, etc. can also be dispersed in the binder.

As the intermediate layer, the same binders and metal oxides as those for the overcoat layer can be used. Furthermore, compounds containing silicon or zirconium can also be used.

As shown in FIGS. 3 and 4, this photosensitive layer 4 may be provided via an intermediate layer 5 provided on a conductive support. When the photosensitive layer 4 has a two-layer structure in this manner, a photoreceptor having the most excellent electrophotographic properties can be obtained. Further, in the present invention, as shown in FIGS. 5 and 6, a photosensitive layer 4 formed by dispersing the carrier-generating substance 7 and a carrier-transporting substance in JIe is formed directly on the conductive support layer 1 or as an intermediate layer. 5 may be provided.

The carrier generation layer 2 constituting the photosensitive layer 114 having a two-layer structure can be formed directly on the conductive support 1 or the carrier transport layer 3, or if necessary, with an intermediate layer such as an adhesive layer or barrier layer provided thereon. It can be formed by the following method.

M-1) A method of applying a solution in which the asymmetric squarium compound according to the present invention is dissolved in a suitable solvent, or a solution in which a binder is added and mixed as necessary.

M-2》A method in which the asymmetric squarium compound according to the present invention is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a binder is added as needed to mix and disperse the resulting dispersion and then applied.

The solvent or dispersion medium used for forming the carrier generation layer includes n-butylamine, diethylamine, ethylenediamine, isoprobanolamine, triethanolamine, triethylenediamine, N. N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, OOform, 1,2-dichloroethane, 1.1.2-trichloroethane, i. Examples include ``+, i-trichloroethane, trichloroethane, tetrachlorethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isobrobanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, and the like.

Further, the carrier transport layer can be formed in the same manner as the carrier generation layer described above.

When using a binder resin to form the carrier generation layer or the carrier transport layer, any binder resin can be used, but it is preferable to use a film-forming polymer that is hydrophobic, has a high dielectric constant, and is electrically insulating. is preferred. Examples of such island polymers include, but are not limited to, the following:

P-1》Polycarbonate P-2》Polyester P-3》Methacrylic resin P-4》Acrylic resin P-5) Polyvinyl chloride P-6》Polyvinylidene chloride P-7》Boristyrene P-8》Polyvinyl acetate P-9 ) Styrene-butadiene copolymer P-10)
Vinylidene chloride-acrylic nitrile copolymer P-11) Vinyl chloride-vinyl acetate copolymer P-12)
Vinyl chloride-vinyl acetate-maleic anhydride copolymer p-13) Silicone resin p-14) Silicone-alkyd resin p-15
) phenol formaldehyde resin p-16) styrene-alkyd resin p-17) poly N-vinyl rubber p-18) polyvinyl butyral p-19) polyvinyl formal p-20) vinyl acetate resin p-21) eboxy resin these These binder resins can be used alone or as a mixture of two or more.

The thickness of the carrier generation layer 2 formed in this way is
It is preferably 0.01 μm to 20 μm, more preferably 0.05 μm to 5 μm. Further, when the carrier generation layer or the photosensitive layer is a dispersion system, the particle size of the asymmetric squarium compound is preferably 5 μm or less, more preferably 1 μm or less.

In the carrier generation layer, the ratio of carrier generation substance to binder is preferably 100:O to 1000. If the content of the carrier-generating substance is less than this, the photosensitivity will be low and the residue potential will increase, and if it is more than this, dark decay and acceptance potential will decrease.

Further, in the carrier transport layer formed as described above, the amount of the carrier transport substance is preferably 20 to 200 parts by weight, particularly preferably 30 to 150 parts by weight, per 100 parts by weight of the binder resin in the carrier transport layer.

Further, the thickness of the carrier transport layer to be formed is preferably 5 to 50 .mu.-1, particularly preferably 5 to 30 .mu.-.

The conductive layer is formed of an inorganic conductive compound such as titanium oxide, tin oxide, copper iodide, carbon, etc. on the conductive support.
It can be formed by dispersing an organic conductive compound such as an organic semiconductor or a conductive polymer in a binder or by applying it as it is.

The asymmetric squarium compound according to the present invention can be subjected to various processes to improve its dispersibility from the viewpoint of particle engineering. For example, wet granulation, spray drying, freeze drying, dry pulverization, etc. can be used.

Further, by changing the crystal form, electrophotographic performance and dispersibility can be improved. For example, the crystal form may change depending on the method of dissolving with an organic amine and then neutralizing and precipitating with an acid, or depending on pressure, temperature, etc.

The conductive support used in the photoreceptor of the present invention includes a metal plate including an alloy, a metal drum or a conductive polymer,
Examples include paper, plastic films, etc. that have been made conductive by coating, vapor depositing, or laminating a thin layer of a metal such as aluminum, palladium, or gold containing a conductive compound or alloy such as indium oxide.

As an intermediate layer such as an adhesive layer or a barrier layer, in addition to the molecular polymer used as the binder, an organic polymer material such as polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, or aluminum oxide is used.

The photoreceptor of the present invention has the above-described structure, and as is clear from the examples described later, it has excellent charging characteristics, sensitivity characteristics, and image forming characteristics, and is particularly resistant to fatigue even when used repeatedly. It has little deterioration and excellent durability.

[Examples] The present invention will be specifically explained below using Examples, but the embodiments of the present invention are not limited thereby.

Example 1 In a 300vf stainless steel pot, put 0.75o of polyvinyl butyral resin (trade name, XYHL), 150mQ of tetrahydrofuran, and 1.50mQ of squarium compound B-2 used in the present invention, and add 150m of glass beads.
Add and disperse with a sand grinder for 48R. This dispersion was applied onto an aluminum evaporator base using a wire bar so that the film thickness after drying was approximately 0.2 μm to form a carrier generation layer (CGL). Next, 7.50 polycarbonate resin (trade name, Vanlite K-1300), 501 g of ethylene chloride, and the following carrier transport material K-14 were added.
．． 00 with a magnetic stirrer. This liquid was added to the CG
Apply carrier transport 1i (CTL) onto L using an applicator so that the film thickness after drying is 20μ.
was formed.

K-1 After being placed in an oven and thoroughly dried, the electrophotographic performance was tested. That is, after being charged by performing -6 KV corona discharge for 5 seconds using an electrostatic copying tester manufactured by Kawaguchi Electric,
Leave it in a dark place for 5 seconds, measure its surface potential V^, then irradiate the photosensitive layer with a tungsten halogen lamp with an illuminance of 14 lux, and calculate the time until the surface potential becomes half of V^. Then, the half-reduced exposure amount E1/2 was determined. As a result VA = -1010V%E 1/2 - 4.0 1
It was ux-sec.

Next, image characteristics and durability were tested using a Konica ■ LD printer (semiconductor laser with light source of 790 ns+±Ions). Good images were obtained in a picture printing test of up to 10,000 sheets.

Examples 2 to 10 Photoreceptors were prepared by changing the carrier generating material (CGM) B-2 and the carrier transporting material (CTM) K-1 as shown in Table 1 in Example 1, and the electron Photographic performance was evaluated. The results are shown in Table 1.

table 1 The CTMs in Table 1 are shown below.

K-2 I《-3 K-4 K-5 K-6 K-8 K-10 Example 11 In Example 1, the idiot who reversed the application order of CGL and CTL was exposed to light in the same way as in Example 1. A body was constructed and tested. (However, the corona charge was set to +6Kv.) Result c.
V A = 1210V, El/2 = 3.6 lux-
It was see. In addition, the images in the image display test of up to 10,000 sheets were good.

Examples 12-20 In Example 11, carrier generating material (CGM) compound B-
Photoreceptors were prepared by changing 2 and carrier transport material (CTM) K-1 as shown in Table 2, and the electrophotographic performance was evaluated in the same manner as in Example 11. The results are shown in Table 2.

Table 2 K-11 K-12 K-13 K-14 K-15 K-16 K-17 K-19 [Effects of the Invention] According to the present invention, as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor By using the asymmetric squarium compound represented by the general formula [I], it has excellent electrophotographic properties such as sensitivity, residual potential, and charge retention, has little fatigue deterioration when repeatedly used, and is resistant to heat and light. It is possible to produce an excellent electrophotographic photoreceptor that is stable in contrast, has sufficient sensitivity even in a long wavelength region of 780 nm or more, and can be used satisfactorily even in a visible light region of 780 nm or less. Further, even in combination with a wide range of carrier transport substances, the use of the asymmetric squarium compound according to the present invention makes it possible to provide a photoreceptor with sufficient sensitivity.

[Brief explanation of drawings]

FIGS. 1 to 6 are cross-sectional views showing structural examples of the electrophotographic photoreceptor of the present invention, and 1 to 7 in the figures represent the following, respectively. 1... Conductive support 2... Carrier generation layer 3... Carrier transport layer 4... Photosensitive layer 5... Intermediate layer 6... Layer containing a carrier transport substance 7... Carrier Generated substance

Claims (3)

[Claims] (1) An electrophotographic photoreceptor comprising, on a conductive support, a photosensitive layer containing at least one asymmetric squarium compound represented by the following general formula [I]. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, Ar_1 and Ar_2 are different from each other,
One of _1 and Ar_2 is selected from the groups represented by the general formula [A] below, and the general formula [A] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2 and R_3 are hydrogen atoms and halogen atoms, respectively. Includes atoms, hydroxyl groups, alkyl groups, cyano groups, nitro groups, aryl groups, ▲mathematical formulas, chemical formulas, tables, etc.▼
(X represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted amino group), ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (R_6 represents a hydrogen atom or an alkyl group) or a substituted amino group , R_4 and R_5 are each a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or NHY
represents. Y represents ▲There are numerical formulas, chemical formulas, tables, etc.▼ or -SO_2-R_8 (R_7 and R_8 each represent a hydrogen atom, an alkyl group, or an aryl group). ) And the other of Ar_1 and Ar_2 has the following general formula [
B], [C], [D], [E], [F] or [G]. General formula [B] ▲ Numerical formulas, chemical formulas, tables, etc. N
Represents HY. Y represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or -SO_2-R_8 (R_7 and R_8 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group.) . X
_1_1 is a substituted or unsubstituted aliphatic hydrocarbon ring, a substituted or unsubstituted aliphatic heterocycle, a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocycle. Represents a group of atoms. R_1_3
and R_1_4 each represent a substituted or unsubstituted alkyl group, and when they jointly form a 3- to 7-membered ring, represent an alkylene group. ) General formula [C] ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (In the formula, X_2_1 and X_2_2 are each substituted or unsubstituted aliphatic hydrocarbon ring, substituted or unsubstituted aliphatic heterocycle, substituted or unsubstituted represents an atomic group necessary to form an aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocycle. R_2_1 and R_2_2 each represent a substituted or unsubstituted alkyl group, and When forming a 3- to 7-membered ring, it represents an alkylene group.) General formula [D] ▲ Numerical formulas, chemical formulas, tables, etc. R_1_1 and R_1_ in B]
It is synonymous with 2. R_3_4 represents a substituted or unsubstituted alkyl group. X_3_1 is a carbon atom group necessary to form an at least 6-membered saturated or unsaturated monocyclic hydrocarbon or polycyclic hydrocarbon, or at least 5-membered carbon atom containing at least one heteroatom other than the nitrogen atom. Each represents a group of atoms necessary to form a ring. ) General formula [E] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_4_1, R_4_2, R_4_3 and R_
4_4 has the same meaning as R_1_1 and R_1_2 in the general formula [B], respectively, and R_4_5 represents a substituted or unsubstituted alkyl group. Ar_4 represents a substituted or unsubstituted naphthyl group, anthranyl group, fused polycyclic group or heterocyclic group. ) General formula [F] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_5_1, R_5_2, R_5_3 and R_
5_4 are synonymous with R_1_1 and R_1_2 of the general formula [B], respectively, and Ar_5_1 and Ar_5_
2 each represents a substituted or unsubstituted naphthyl group, anthranyl group, fused polycyclic group or heterocyclic group. ) General formula [G] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_6_1, R_6_2 and R_6_3 are synonymous with R_1_1 and R_1_2 of the above general formula [B], respectively, and R_6_4, R_6_5, R_6_6 and R_6_7 each represents a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group.Ar_6 is
Represents a substituted or unsubstituted aryl group. )] (2) The electronic photosensitive layer according to claim (1), wherein the photosensitive layer contains a carrier transporting substance and a carrier generating substance, and at least one of the carrier generating substances is an asymmetric squarium compound represented by the general formula [I]. Photographic photoreceptor. (3) The photosensitive layer has a laminated structure of a carrier-generating layer containing an asymmetric squarium compound represented by the general formula [I] as at least one carrier-generating substance, and a carrier-transporting layer containing a carrier-transporting substance. The electrophotographic photoreceptor according to claim (1) or (2).