JPH0223360A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the photosensitive body which has high sensitivity, small residual potential and excellent durability by incorporating a specific squarylium compd. therein. CONSTITUTION:A photosensitive layer 4 into which at least one kind of the squarylium compds. expressed by formula I, etc., are incorporated is provided on a conductive base 1. In formula I, either of Ar1 and Ar2 is selected from formula II and other from formula III. In formula II R0, R1, R3 denotes a hydrogen atom, alkyl group, alkoxy group, etc.; R3 denotes an alkyl group; X1 denotes the carbon atom group necessary for forming at least 6-membered monocyclic or polycyclic hydrocarbon. In formula III, R6, R7 denote 1-20C alkyl group and phenyl group in the case of the groups are independent from each other and denote an alkylene group when the groups jointly form the 3-7-membered nitrogenous heterocycles; R8 denotes a hydrogen atom, hydroxyl group, methyl group, trifluoromethyl group, etc. The photosensitive body which has the excellent characteristics such as sensitivity, residual potential and charge holding power and is less deteriorated with fatigue 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 squareium compound.

[Prior Art] Conventionally, inorganic photoreceptors having a photosensitive layer containing an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide, or silicon as a main component 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, when selenium crystallizes, its properties as a photoreceptor deteriorate, making it difficult to manufacture.Also, selenium crystallizes due to heat, fingerprints, etc., and its performance as a photoreceptor deteriorates. In addition, cadmium sulfide has problems with moisture resistance and durability, and zinc oxide has problems with durability, etc.

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-vinylcarbazole lintro-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 these type of functionally separated photoreceptors because each material can be selected from a wide range and photoreceptors with arbitrary performance can be created 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. However, the drawback that the carrier generation layer crystallizes due to heat and deteriorates the characteristics as a photoreceptor has not been improved.

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

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

Although the squalium compounds disclosed in Japanese Patent Application Laid-open No. 49-105536 have relatively high sensitivity, they have drawbacks in chargeability, dark decay, etc., and have not been able to achieve both high sensitivity and low dark decay.

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 are characterized by being capable of 0N10FF in time series, and are particularly promising as a light source for copying machines and computer output printers with image processing functions, such as intelligent copiers. 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 lower output than a gas laser, and the excavation wavelength is also a long wavelength (approximately 780 nm or more), so in many conventional electrophotographic photoreceptors, the spectral sensitivity is on the short wavelength side. There were no practically satisfactory sensitivity characteristics.

[Object of the Invention] An object of the present invention is to provide an electrophotographic photoreceptor containing a specific squareium compound having excellent carrier generation ability.

Another object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity, low rA retention potential, and excellent durability whose characteristics do not change even after repeated use.

Still another object of the present invention is to provide an electrophotographic photoreceptor containing a squalium 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 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 squalium compound can act as an active ingredient of an electrophotographic photoreceptor. The present invention has now been completed.

That is, the object of the present invention is to have a photosensitive layer containing at least one squalium compound represented by the following general formula [I], [I[] or [III] on a conductive support. This is accomplished using an electrophotographic photoreceptor.

In formula 1, Ar+ and Ar2 are different from each other, and Ar+
and one of A1 and A1 is selected from the following general formula [A], - clothing [A] (wherein Ro, R1 and R2 are each a hydrogen atom,
Represents a halogen atom, alkyl group, alkoxy group, hydroxyl group or NHY. Y is -C-R+ or -8O2-
R5 (R4 and R5 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group). R3 represents a substituted or unsubstituted alkyl group. x1 represents a group of carbon atoms necessary to form an at least 6-membered saturated or unsaturated 11-ring or polycyclic hydrocarbon. ) and At”
+ The other of Ar2 is the following - Clothes cost [B], [C]
or [D].

(In the formula, when R6 and R7 are each independent of each other, they are each a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted allf
i represents a phenyl group, or R6 and R7 jointly represent 3
When a nitrogen-containing heterocycle having 7 to 7 shells is formed, these represent a substituted or unsubstituted alkylene group. R8 is a hydrogen atom, water II! group, methyl group, trifluoromethyl group, halogen atom or carboxyl group. ) - Clothing cost [C] (wherein, R9 has the same meaning as R6 and R7 of the above-mentioned - Clothing cost [B] (however, excluding the platform where R6 and R7 cooperate with each other to form a ring), Rlo has the same meaning as R8 in the above-mentioned -Fukudai [8], and R++ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms,
halogen atom, nitro group, cyano group, carboxyl group,
It represents an alkoxycarbonyl group or a trifluoromethyl group having 1 to 4 carbon atoms. ) General formula [D] (wherein, RI2 has the same meaning as Ra of the above-mentioned -Fukudai [B], and RI3 and RI4 each represent RIT of the above-mentioned -Fukudai [])
is synonymous with ) [In the formula, AI''3 and Ar4 are different from each other, and Ar3
and 8. One of the rumors is selected from the following - Clothes cost [△], (Ro, R+ and R2 are each hydrogen atom, halogen atom, alkyl group, alkoxy group, hydroxyl group or N
Represents HY, Y is -C-R4 or -3O2-R5
(R4 and R5 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group). R3 represents a substituted or unsubstituted alkyl group. x1 represents a carbon atom group necessary to form an at least 6-membered saturated or unsaturated monocyclic or polycyclic hydrocarbon. ) And the other of Ar3 and Ar4 is the following - Clothes cost [E
], [F] or [G].

- Clothes cost [E] (In the formula, RI5.R+6 and R17 are respectively synonymous with Ro, R+ and R2 in - Clothes cost [A].

R+a represents a substituted or unsubstituted alkyl group.

x2 represents an atomic group including at least one heteroatom other than the nitrogen atom and necessary to form a ring having at least 5 members as a whole. ) General formula [F] represents a hydrogen atom, an alkyl group or a halogen atom. Are represents a substituted or unsubstituted aryl group. ) (In the formula, R+s, R20, R2+ and R22 have the same meanings as Ro, R+ and R2 in the above-mentioned -fukudai [A], respectively, and R23 represents a substituted or unsubstituted alkyl group. Al'5 is , represents a substituted or unsubstituted phenyl group, naphthyl group, anthranyl group, fused polycyclic group or heterocyclic group.) [In the formula, Ar? and AI'a are different from each other and Ar7
One of and Ara is selected from the following - clothing cost [A], and the other is selected from the following - clothing cost [A']. ] General formula [A] - clothing cost [A'] (in the formula, R
2+, R25 and R26 are respectively the above - clothes cost [A
] is synonymous with Ro, R+ and R2, and R27
, R28, R29 and R2O are (Ro, R+
and R2, Ra', R+' and R2' each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group or NHY. Y is 10-R4 or 18O2-Rs (R4 and R5 are each a hydrogen atom,
Represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted phenyl group. ). R3 and R
3' each represents a substituted or unsubstituted alkyl group. Xl and X+' each represent a group of carbon atoms necessary to form an at least 6-membered saturated or unsaturated monocyclic or polycyclic hydrocarbon. However, Ro and Ro
', R? and R+', R2 and R2' and ×1
and X+', at least one is a mutually different group. ) Hereinafter, the squalium compound of the present invention will be specifically shown.

One of the squalium compounds of the present invention has the general formula % Formula % Either one of Ar2 is selected from the above-mentioned general formula [A]. - In clothing [A], the alkyl group represented by Ro, R1 and R2 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 representative examples of the substituent include a halogen atom,
Examples include hydroxyl group and alkoxy group. Specific examples of the alkyl group include a methyl group, an ethyl group, a chloromethyl group, and the like, and among these, a methyl group is preferred.

Examples of the halogen atom represented by Ro, R+ and R2 include a chlorine atom, a bromine atom, a fluorine atom and the like.

The alkoxy groups represented by Ro, R+ and R2 preferably have 1 to 7 carbon atoms, and specific examples thereof include methoxy and ethoxy groups.

Y in NHY represented by Ro, R+ and R2 represents 啜-C-Rto or -302-Rs, but R4 and R
Examples of the alkyl group which may have 5 substituents include a methyl group, an ethyl group, a propyl group, and the like. Examples of the phenyl group include a phenyl group and anisoyl group.

Hereinafter, specific examples of the squareium compound useful in the present invention are shown below, but the squareium compound of the present invention is not limited thereto.

Margin below ■-11 ■-12 ■-14 knee 15 ■-16 ■-22 ■-23 ■-24 knee 17 ■-18 ■-19 ■-25 ■-26 ■-29 ■-30 ■-31 ■-32 ■-38 ■-40 C2H.

death! rθ Shil knee 33 ■-38 E-6 E-21 E-22 E-37 E-38 F-14 F-16 Circle 1-11; IJ city vinegar H3 F-29 F-30 vinegar G-2 G-17 G-18 death! ni Mri G-33 I-5 I[1-6 ■-8 Margin below m-t.

ll-11 [[-12 ■-13 ■-14 ■-15 ■-16 [1-21 [-22 ■-23 1g-24 ■-17 ■-18 ■-20 [-26 -zs ■-29 ■ -30 ■-31 ■-32 ■-37 ■-38 ■-39 ■-40 ■-33 ■-34 ■-36 The compound of the present invention represented by the general formula [I], [II] or [I[[] Squarium compounds are disclosed in, for example, JP-A-62-26
No. 7753 and Tetrahedron Letters (Tetra
hedron 1etters) NO, 10, pp
, 781-782゜1970 and Synthesis (S y
(nthesis) ap, 961° in 1980, it can be synthesized in four steps as shown by the formula below.

In the first step, thionyl chloride and N,N-dimethylformamide are added to squaric acid of formula (A), and the mixture is heated to approximately 100°C.
3,4-dichloro-3-cyclobutene-1
, 2-dione (B) is obtained.

In the second step, the 3゜4-dichloro-3-cyclobutene-1,2-dione of formula (B) obtained in the first step is added to
5 molar ratio of Ar2-H of formula (C) and the above Ar2 in a solvent.
The compound of formula (D) is obtained by reacting at a temperature below room temperature in the presence of AlC,23 in a molar ratio of 1 or more to -H.

Examples of the solvent used in the second step include dichloromethane, carbon tetrachloride, 1,2-dichloroethane, and other solvents commonly used in Friedel-Krach reactions. Further, instead of AffiCe3, a Lewis acid such as aluminum chloride, antimony chloride, iron chloride, titanium chloride, boron trifluoride, tin chloride, hismuth chloride, or zinc chloride may be used as a catalyst.

In the third step, the compound of formula (D) obtained in the reaction of the second step is hydrolyzed to form a compound of formula (E).

Hydrolysis can be carried out, for example, by refluxing in acetic acid containing a small amount of water.

In the fourth step, the compound of formula (E) obtained and isolated in the third step is refluxed in a solvent or by a reduced pressure method to Ar+ − of formula (F).
The desired asymmetric squalium compound (I) is obtained by reacting with H. The solvent used here has 2 carbon atoms.
1 to 10 primary or secondary alcohols, or azeotropic mixtures of these alcohols and aromatic hydrocarbons such as benzene, toluene, and xylene can be used.

The squalium compound of the present invention can also be obtained by a general synthesis method for squalium compounds. That is, a total of 2 moles of two different types of amine derivatives can be simultaneously reacted with 1 mole of square phosphoric acid. However, the squalium compound obtained by this WA is a mixture of an asymmetric squalium compound and a symmetric squalium compound, and it is difficult to control the ratio of the products and to separate each product, and there is a large variation in electrical properties and sensitivity. The former method is preferable since it has problems such as causing a decrease in .

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

Synthesis Example (Synthesis of Exemplified Compound 1-21) (Synthesis of Dicyclobutenedione (B)) 500.0 g of benzene to 10 g of squaric acid. Q and thionyl chloride 140d
and 51 g of N,N-dimethylformamide, and the external temperature was 1.
Stir at 00° C. for 2 hours. After distilling off the solvent, n-
Crystallize with hexane.

After washing with n-hexane several times by decantation, drying under reduced pressure,
58 g (yield 44%) of dicyclobutenedione (B) was obtained.

The following margin (synthesis of chloride (D)) Add 53 (1) aluminum chloride to 360 (360) methylene chloride and stir at about 0°C. Dicyclobutenedione (B) 5
Bond with 0g added, aniline derivative (C) 81! ;1 was dissolved in methylene chloride 1801R and added dropwise while keeping the chamber at 0°C. Stir at internal O 0 C for 4 hours.

1 part of methylene chloride and 12 parts of distilled water are added, stirred, and then allowed to stand to obtain a methylene chloride layer. After washing with water, dry with a sieve, and methylene chloride is distilled off under reduced pressure. Purification was performed using a silica gel column to obtain 90 g (yield: 75%) of chloride (D) as crystals.

(Synthesis of OH form (E)) Chlor form (D>30111, 100 g of acetic acid and 10 g of distilled water
Add n12 and heat to reflux for 3 hours while stirring.

After cooling, add 4ffi of distilled water, add 50 g of hydrochloric acid, stir, and filter through a suction funnel. Washing with water, n-hexane, and drying under reduced pressure gave OH form (E) 24 (1 (yield 84%)) as crystals.

(Synthesis of Exemplary Compound ■-21) OH form (E) 23 (l i, 11-hep'2/-41f
fi and Compound (F) 21.20 were added, and the mixture was stirred and heated under reflux for 2 hours under reduced pressure. Hot piece suction filter, acetone 2
Wash 3 times with y. After drying under reduced pressure, 22 g of the target exemplary compound Ni 21 was obtained as green crystals (yield: 54%).
) 1 move.

Elemental analysis CHN calculation (direct (%) 71.95 4.9
8 4.94 Actual value (%) 71.91 5
．． 00 4.91 Spectral absorption spectrum (in methylene chloride) λmax = 636 nm Infrared absorption spectrum (in KBr) vmax = 1590 Cm-' (c=o) Melting point (Japanese Pharmacopoeia melting point measurement method) 237°C Said squalium compound of the present invention has excellent photoconductivity, and when producing a photoreceptor using it, it can be produced by providing a photosensitive layer in which the squareium compound of the present invention is dispersed in a binder on a conductive support. However, among the photoconductivity possessed by the squalium compound of the present invention, by using it as a carrier generating substance by taking advantage of its particularly excellent carrier generating ability, and using it together with a carrier transporting substance that can effectively act in combination with this, Particularly excellent results can be obtained when a so-called functionally separated photoreceptor is constructed. 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 squalium 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 trinitrofluorenone or tetranitrofluorenone, as well as poly- Polymers having a heterocyclic compound in the side chain such as N-vinylcarbazole, triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, polyarylalkane derivatives, phenylenediamine derivatives, todracine derivatives, amine substitution Examples of electron-donating substances that easily transport holes include carbon derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives, phenothiazine derivatives, azine derivatives, butadiene derivatives, Schiff base derivatives, etc., and the carrier transporting substance used in the present invention is not limited to these.

Various types of mechanical configurations of photoreceptors are known, and the photoreceptor of the present invention can take any of these forms.

Usually, the configuration is as shown in FIGS. 1 to 6. Figure 1 shows an example of a negatively charging photoreceptor, in which a carrier generation layer 2 containing a squareium compound as a main component is placed on a conductive support 1.
This is a case in which a photosensitive layer 4 is provided on which a carrier transport layer 3 containing a carrier transport substance as a main component is provided in a laminated configuration.

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. A compound containing silicon or zirconium may 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 comprising a carrier generating substance 7 and a carrier transporting substance dispersed in a layer 6 is formed on the conductive support 1 directly or in an intermediate manner. It may be provided via layer 5.

The carrier generation layer 2 constituting the two-layered photosensitive layer 4 may be applied directly to the conductive support 1 or the carrier transport layer 3, or if necessary, after providing an intermediate layer such as an adhesive layer or a barrier layer, for example. It can be formed by the following method.

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

M-2) Ball milling the squalium compound of the present invention,
A method in which fine particles are made into fine particles in a dispersion medium using a homomixer, etc., and a binder is added as necessary to mix and disperse the resulting dispersion.

Solvents or dispersion media used to form the carrier generation layer include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, acetone, methylethylketone, cyclohexanone, and benzene. , toluene, xylene, chloroform, 1.2-dichloroethane, 1,1.2-trichloroethane, 1.1.1-trichloroethane, trichloroethane, tetrachloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate , butyl acetate, dimethyl sulfoxide and the like.

When using a binder in the carrier generation layer or carrier transport layer, any binder 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. preferable. Examples of such high molecular weight polymers include the following:
It is not limited to these.

P-1) Polycarbonate P-2> Polyester P-3) Methacrylic resin P-4) Acrylic resin P-5) Polyvinyl chloride P-6) Polyvinylidene chloride P-7) Polystyrene P-8) Polyvinyl acetate P-9 ) Styrene-butadiene copolymer P-10) Vinylidene chloride-acrylonitrile copolymer P-11) Vinyl chloride-vinyl acetate copolymer P-42
> 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- Vinylcarbazole P-18
>Polyvinyl butyral P-19) Polyvinyl formal p-20) Vinyl acetate resin P-21) Epoxy resin These binders can be used alone or in 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 μl to 5 μm. Further, when the carrier generation layer or the photosensitive layer is a dispersed type, the grain size of the squalium compound is preferably 5 μm or less, more preferably 1 μm or less.

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 squalium compound of the present invention can be subjected to various processes to improve its dispersibility from the viewpoint of powder and granule engineering. For example, wet granulation, spray drying, freeze drying, dry pulverization, etc. can be used.

Furthermore, 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, 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 high molecular weight polymer used as the binder, 1. Organic polymer substances such as polyvinyl alcohol, ethyl cellulose, and carboxymethyl cellulose, or aluminum oxide are 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.

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

(Example 1) In a 300 series stainless steel pot, polyvinyl butyral resin (trade name, XYHL) 0.75 (), tetrahydrofuran 150% and Squarium compound l-211,5
Add 150 glass peas and disperse with a sand grinder for 48 hours. This dispersion was placed on an aluminum vapor-deposited base so that the film thickness after drying was approximately 0.2μ.
Apply with wire bar and carrier generation FJ (CGL)
was formed. Next, 7.5 g of polycarbonate resin (trade name, Panlite K-1300) and 50 g of ethylene chloride were added.
1g and -14,0(+) are mixed with the following carrier transport substance using a magnetic stirrer.This liquid is applied onto the CGL using an applicator so that the film thickness after drying is 20μ, and the carrier Transport 11 (CTL) was formed.

-1 In Example 1, a photoreceptor was prepared by changing the carrier generating material (CGM) I-21 and the carrier transporting material (CTM) K-1 as shown in Table 1, and the electrophotographic performance was improved in the same manner as in Example 1. was evaluated. The results are shown in Table 1.

After that, the blank was placed in an oven and after being thoroughly dried, the electrophotographic performance was tested. That is, after being charged by performing a corona discharge of 16 KV 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 VA, 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 VA. The half-life exposure ffi E 1/2 was determined. As a result, VA=-1205V, E1/2--2.9
It was 1ux-sec.

Next, the image characteristics and durability were tested using an LD printer manufactured by Nijika (semiconductor laser with a light source of 790r+n±10 nm). Good images were obtained in a picture printing test of up to 10,000 sheets.

Examples 2-10 table ni-2 ni-3 ni-4 ni-5 The CTMs in Table 1 are shown below.

-9 to -10 to -18 C! Margin Example 21 A photoreceptor was produced and tested in the same manner as in Example 1, except that the order of application of CGL and CTL was reversed. (However, the corona charge was +6KV.) The result is V^=
1520, El/2-2.0 tux·sec. In addition, the images in the image display test of up to 10,000 sheets were good.

Examples 22 to 40 In Example 21, photoreceptors were prepared by changing the carrier generating substance (CGM) ■-21 and the carrier transporting substance (CTM) K-1 as shown in Table 2, and the photoreceptors were prepared in the same manner as in Example 21. The electrophotographic performance was evaluated. The results are shown in Table 2.

Margin below The CTMs in Table 2 are shown below.

−25 −22 −23 −28 −24 −29 −30 −31 −32 −36 [Effects of the Invention] According to the present invention, the light constituting the photosensitive layer of an electrophotographic photoreceptor As a conductive substance, the above-mentioned clothes [I], [II] or [I
By using the squareium compound represented by [l], it has excellent electrophotographic properties such as sensitivity, residual potential, and charge retention, has little fatigue deterioration when used repeatedly, and is stable against heat and light. Yes, plus 780rv
It is possible to produce an excellent electrophotographic photoreceptor that has sufficient sensitivity even in the above long wavelength range and can be used satisfactorily even in the visible light range of 780 nl or less. Further, by using the squalium compound of the present invention, it is possible to provide a photoreceptor having sufficient sensitivity even in combination with a wide range of carrier transport substances.

[Brief explanation of the drawing]

1 to 6 are sectional views showing examples of the mechanical structure 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 carrier transport substance 7... Carrier generation material

Claims (5)

[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 general formula [A] below, and the general formula [A] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_0, R_1 and R_2 are hydrogen atoms, halogen atoms, alkyl groups, alkoxy represents a group, hydroxyl group, or NHY.
hydrogen atom, substituted or unsubstituted alkyl group,
Or represents a substituted or unsubstituted phenyl group. ). R_3 represents a substituted or unsubstituted alkyl group. X_1 represents a group of carbon atoms necessary to form an at least 6-membered saturated or unsaturated monocyclic or polycyclic hydrocarbon. ) The other of Ar_1 and Ar_2 is selected from the following general formula [B], [C], or [D]. General formula [B] ▲ Numerical formulas, chemical formulas, tables, etc. R_8 represents an alkyl group, a substituted or unsubstituted phenyl group, or when R_6 and R_7 together form a 3- to 7-membered nitrogen-containing heterocycle, they represent a substituted or unsubstituted alkylene group.
represents a hydrogen atom, a hydroxyl group, a methyl group, a trifluoromethyl group, a halogen atom or a carboxyl group. ) General formula [C] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_9 is R_6 and R_ of the above general formula [B]
7 (except when R_6 and R_7 cooperate with each other to form a ring), and R_1_0 is the same as the general formula [
B] has the same meaning as R_8, and R_1_1 is a hydrogen atom,
Alkyl group having 1 to 6 carbon atoms, hydroxyl group, 1 carbon atom
-4 alkoxy group, halogen atom, nitro group, cyano group, carboxyl group, alkoxycarbonyl group having 1 to 4 carbon atoms, or trifluoromethyl group. ) General formula [D] ▲ Numerical formulas, chemical formulas, tables, etc. ) (2) An electrophotographic photoreceptor comprising, on a conductive support, a photosensitive layer containing at least one asymmetric squarium compound represented by the following general formula [II]. General formula [II] [In the formula, Ar_3 and Ar_4 are different from each other, and Ar
One of _3 and Ar_4 is selected from the general formula [A] below, and the general formula [A] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_0, R_1 and R_2 are hydrogen atoms, halogen atoms, alkyl groups, alkoxy represents a group, hydroxyl group, or NHY.
hydrogen atom, substituted or unsubstituted alkyl group,
Or represents a substituted or unsubstituted phenyl group. ). R_3 represents a substituted or unsubstituted alkyl group. X_1 represents a group of carbon atoms necessary to form an at least 6-membered saturated or unsaturated monocyclic or polycyclic hydrocarbon. ) The other of Ar_3 and Ar_4 is selected from the following general formula [E], [F], or [G]. General formula [E] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1_5, R_1_6 and R_1_7 are respectively R_0, R_1 and R_2 in general formula [A]
is synonymous with R_1_8 represents a substituted or unsubstituted alkyl group. X_2 represents a group of atoms necessary to form at least a 5-membered ring as a whole, including at least one heteroatom other than the nitrogen atom. ) General formula [F] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1_9, R_2_0, R_2_1 and R_
2_2 is R_0 in the general formula [A], respectively.
, R_ and R_2, and R_2_3 represents a substituted or unsubstituted alkyl group. Ar_5 represents a substituted or unsubstituted phenyl group, 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_2_4, R_2_5 and R_2_6 are respectively synonymous with R_0, R_1 and R_2 in the above general formula [A], R_2
_9 and R_3_0 each represent a hydrogen atom, an alkyl group, or a halogen atom. Ar_6 represents a substituted or unsubstituted aryl group. ) (3) An electrophotographic photoreceptor comprising, on a conductive support, a photosensitive layer containing at least one squarium compound represented by the following general formula [III]. General formula [III] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, Ar_7 and Ar_8 are different from each other,
One of _7 and Ar_8 is selected from the following general formula [A], and the other is selected from the following general formula [A']. ] General formula [A] General formula [A'] ▲There are mathematical formulas, chemical formulas, tables, etc.▼▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_0, R_1 and R_2 and R_0', R_1'
and R_2' each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group or NHY. Y is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or -SO
_2-R_5 (R_4 and R_5 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group). R_3 and R_3' each represent a substituted or unsubstituted alkyl group. X_1 and X_1' are each at least 6
Represents a group of carbon atoms necessary to form a saturated or unsaturated monocyclic or polycyclic hydrocarbon. However, R_0
and R_0', R_1 and R_1', R_2 and R_2', and X_1 and X_1', at least one of which is a different group. ) (4) The photosensitive layer contains a carrier-transporting substance and a carrier-generating substance, and at least one of the carrier-generating substances is a squarium compound represented by the general formula [I], [II], or [III]. The electrophotographic photoreceptor according to item (1), (2) or (3). (5) The photosensitive layer comprises a carrier generating layer containing a squarium compound represented by the general formula [I], [II] or [III] as a carrier generating substance, and a carrier transporting layer containing a carrier transporting substance. The electrophotographic photoreceptor according to claim 1, having a laminated structure.