JPH03216660A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve electrophotographic characteristics, such as sensitivity, residual potential and charge holding power, by providing a photosensitive layer contg. 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, one of Ar1, 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 formu la II, R1 to R3 respective denote an alkoxy group, hydrogen atom, etc., or halo gen atom or R4, R5 respectively denote a hydrogen atom, halogen atom, etc. In the formula III, R11, R12 respectively denote a hydrogen atom, halogen atom, etc.; X11 denotes a substd. or unsubstd. aliphat. hydrocarbon ring, etc.; R13, R14 respectively denote a substd. or unsubstd. alkyl group. The electrophotographic characteristics, such as sensitivity, residual potential and charge holding power, are improved 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.

[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, 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, in Japanese Patent Publication No. 50-10496, there are
There is a description of an organic photoreceptor having a photosensitive layer containing luorenone. 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,
Viryliums, squariums, etc. are known.
Futacyanines, 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 780 nm or more), so in many conventional electrophotographic photoreceptors, the spectral sensitivity is on the short wavelength side. In terms of sensitivity characteristics,
There was nothing that was practically satisfying.

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.

Further 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 E formula, Ar+ and A'2 are different from each other, and Ar+
and Ar2 are selected from the groups represented by the following general formula [A], where R+ .R2 and R3 each represent an alkoxy group, a hydrogen atom, all water, a halogen atom, or an alkyl group. R4 and R5 each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an O hydroxyl group, or NHY. Y is 10-Rs or -80
2 -R7 (R6 and R7 each represent a hydrogen atom, an alkyl group, or an aryl group).However, R
＋． At least one of R2 and R3 is an alkoxy group. ) The other of Ar+ and AI'2 is represented by the following general formula [
81, [C]. [D], [E]. It is selected from the group represented by [F] or [G].

General formula [B] ゛・×1′1 (wherein Rat and R+2 are each a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, water RM or 0 i Represents NHY.Y is -C-Rs or -302
-R7 (Rs and R1 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group).Xu represents a substituted or unsubstituted aliphatic hydrocarbon ring, a substituted or unsubstituted aliphatic hydrocarbon ring, 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. R13 and R14 are each substituted or unsubstituted. Represents an alkyl group substituted with W1, or represents an alkylene group when these together form a 3- or 7-membered ring.) General formula [C] (wherein, X21 and X22 are each substituted or unsubstituted The atomic groups necessary to form an aliphatic hydrocarbon ring, a substituted or unsubstituted m-aliphatic heterocyclic ring, a substituted or unsubstituted aromatic m-hydrogenated 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, represent an alkylene group. (In the formula, R3t, R32 and Ra3 have the same meanings as Ru and R+2 in 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, R4+.R42.R43 and R44 are respectively synonymous with Rh and RI2 in the general formula [8], and R
45 represents a substituted or unsubstituted alkyl group.

Ar+ represents a substituted or unsubstituted naphthyl group, anthranyl group, fused polycyclic group or heterocyclic group. ) General formula [F] (wherein, Rs1, R!+2.Rs3 and R54 are 1, each having the same meaning as Ru and R12 in the general formula [8],
A'51 and Ars2 each represent an @-substituted or unsubstituted naphthyl group, anthranyl group, fused polycyclic group, or heterocyclic group. ) hit κ63 (wherein, Rs+.Rs2 and R63 are respectively synonymous with Ru and RI2 in the general formula [B], and R64, R
65, R66 and R67 each represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group.

Ars represents a substituted or unsubstituted aryl group.

)] 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 [
1], one of Ar+ and Ar2 in the general formula [I] is selected from the groups represented by the above general formula [A], and the other Ar+ or Ar2 is represented by the above general formula [B]. [C]. [D], [E], [F] or [G
] is selected from the groups represented by.

R+ in general formula [A]. The alkoxy group represented by R2 or R3 preferably has 1 to 5 carbon atoms.

In addition, R++ and R12 in general formula [B], general formula [
D] in R3+. R32 and R33, general formula [E]
R4+. R42, R43 and R44, general formula [
F] Rs+. R52. R53 and R54, 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.

R++ and R+2 in general formula [81, general formula [01
Ra+. R32 and R33, R4+ in general formula [E]. R42. R43 and R44, general formula [F]
Rs+. R52. R59 and R54, general formula [
G] in R6+. 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 [8] represents 0 1I -C-Rs or -802-R7, but R6 and R
Examples of the alkyl group represented by 7 include a methyl group, an ethyl group, and a probyl group.

Examples of the alkyl group for R+3 and Rn in the general formula [8] include a methyl group, an ethyl group, a probyl group, a heptyl group, and the like. R45 in the general formula [E] represents an alkyl group that may have a substituent, and representative examples of the substituent include an alkyl group, a phenyl group, and water IiI&! ,
Examples include an alkoxy group and a halogen atom. Further, examples of the aryl group of Ars in the general formula [G] 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 n B-5 B-6 B-7 B-10 B-11 B-12 0 0 0 B-13 B-14 B-15 B-16 B-17 0 0 B-18 B-20 B-21 B-22 0 0 B-29 B-30 0 0 B-31 B-32 B-34 C-18 D-2 D-3 D-4 U ri0 D-9 U D-10 D-15 D-16 D-17 D-18 D-19 D-20 D-21 D-22 D-23 D-24 U D-25 E-18 O 1 CH3 E-20 O E-21 E-22 n F-10 Exemplary Compound G-2 G-3 G-19 The asymmetric squarium compound of the present invention represented by the general formula [I] is disclosed in, for example, JP-A-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. In the first step, a solvent is added to the acid chloride of formula (A), and then tetraethoxyethylene (B) and an organic amine are added. In addition,
Make it 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 (D) obtained and isolated in the third step is refluxed in a solvent or by a reduced pressure method to Ar2- of formula (E).
The desired asymmetric squarium compound (F) 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.

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

(Synthesis of compound (H)) Penzyl chloride (G) 220o was added to 2L of n-hexane, and tetraethoxyethylene (B) 209
g and 104 o of triethylamine are added and stirred for about 10 hours. Then treated with aluminum oxide soog,
Compound (H) 224Q was obtained. Yield 65%.

(Synthesis of compound (1)) Compound (H) 20% salt to 224Q! ! Add 1 cup of water and heat under reflux for 5 hours. After post-treatment, the OH form (1) was converted to 13
I got 6g. Yield 87%.

(Synthesis of Exemplary Compound B-1) OH form (1) 136(] to 1-hebutanol 52
and 102 g of compound (J) were added, and the mixture was heated under reduced pressure for 2 hours.
Stir and heat under reflux. Suction filter when hot, add 10 f of acetone
Wash 3 times with fi. It was dried under reduced pressure to obtain 111 g of the target exemplary compound 8-1. Yield 78%.

Elemental analysis CHN Calculated value (%) 73.66 6.39 3.
58 Actual value (%) 73.60 6.44 3.
52 Spectral absorption spectrum (in methylene chloride) λmax
=643ni (in methylene chloride) Infrared absorption spectrum in CKBr》 v Illax = 1590 cm-1 (C = O
) Melting point (Japanese Pharmacopoeia melting point measurement method) 233°C The asymmetric squarium compound according to the present invention has excellent photoconductivity, and when a photoreceptor is manufactured using it, the present invention is applied onto a conductive support. It can be produced by providing a photosensitive layer in which an asymmetric squarium compound is dispersed in a binder. However, among the photoconductivity possessed by the asymmetric squarium compound according to the present invention, the particularly excellent carrier generation ability is utilized. Particularly excellent results can be obtained when a so-called functionally separated photoreceptor is constructed by using it as a carrier-generating substance and a carrier-transporting substance that can act effectively 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, the carrier-transporting substance used in combination with it may be an electron-accepting substance that easily transports electrons, such as trinitrofluorenone or te]-ranitrofluorenone. In addition, polymers having a heterocyclic compound in the side chain such as poly-N-vinyl Rubazole, triazole derivatives, oxadiazole derivatives,
imidazole derivatives, birazoline derivatives, polyarylalkane derivatives, phenylenediamine derivatives, hydrazone derivatives, amino-substituted calgon derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives,
Examples of electron-donating substances that easily transport holes include phenothiazine derivatives, azine derivatives, butadiene derivatives, Schiff base derivatives, vorisilane derivatives, and vorianiline derivatives, but the carrier transporting substance used in the present invention is not limited to these. do not have.

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

Usually, the configuration is as shown in FIGS. 1 to 6. 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 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. 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. In this way, when the photoreceptor Ii4 has a two-layer structure, 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, an intermediate layer such as an adhesive layer or a barrier layer may be 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.

Examples of the solvent or dispersion medium used for forming the carrier generation layer include n-butylamine, diethylamine, ethylenediamine, isobrobanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, acetone, methylethylketone, cyclohexanone, benzene, Toluene, xylene, chloroform, 1,2-dichloroethane, 1,1.2-trichloroethane, 1.1.1-trichloroethane, tricooethane, tetrahydrofuran, dichloromethane, tetrahydrofuran, dioxane , methanol, ethanol, isopropanol, 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 high molecular weight 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-acrylonitrile copolymer P-11) Vinyl chloride-vinyl acetate copolymer P-1
2) Vinyl chloride-vinyl acetate-maleic anhydride copolymer p-13) Silicone resin P-14) Silicone-alkyd resin p-Is) Phenol formaldehyde resin p-
16) Styrene-alkyd resin p-17) Poly N-vinyl Rubazole p-ia) Polyvinyl butyral p-19) Polyvinyl formal P-20> Vinyl acetate resin P-21) Eboxy resin This. 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
The thickness 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 weight ratio of the carrier generation substance to the binder is preferably 100:Q 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 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. .

The thickness of the carrier transport layer to be formed is preferably 5 to 50 μl, particularly preferably 5 to 30 μl.

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 an S-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 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 1 300. (Into a stainless steel pot, put 0.751 J of polyvinyl butyral resin (trade name, XYHL), 150 ml of tetrahydrofuran, and 1.5 a of squarium compound B-1 used in the present invention, add 150 d of glass beads, and use a sand grinder. This dispersion was applied onto an aluminum vapor-deposited base using a wire bar so that the film thickness after drying was about 0.2μ to form a carrier generation layer (CGL).Next, Polycarbonate resin (product name: Vanlite K-1300)
7.5o, 501 g of ethylene chloride, and the following carrier transport substance K-14. oa with a magnetic stirrer. This liquid was applied onto the CGL using an applicator so that the film thickness after drying was 20 μm to form a carrier transport layer (CTL).

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 ^^, 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 ^^. Then, the half-decreased exposure IE1/2 was determined. As a result, V^=-1420V, E1/2 = 2.9 lu
It was x-sec.

Next, image characteristics and durability were tested using a Konica ■ LD printer (semiconductor laser with a light source of 79 Orv±Ions). Good images were obtained in a picture printing test of up to 10,000 sheets.

Examples 2 to 10 In Example 1, carrier generating substance (CGM) compound B-1
Photoreceptors were prepared by changing the carrier transport material (CTM) K-1 as shown in Table 1, and the electrophotographic performance was evaluated in the same manner as in Example 1. The results are shown in Table 1. The CTM in Table 1 is shown below.

K-2 K-3 K-4 K-5 K-6 K-7 K-8 K-9 K-10 Example 11 Example 1 except that the application order of CGL and CTL was reversed. A photoreceptor was prepared and tested in the same manner as in Example 1. (However, the corona charge was set to +6Kv.) The results are as follows.
VA = 1320V, E 1/2 = 3.0t
It was ux-Set. 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 1 and carrier transport monomer (CTM) K1 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 an alkoxy group and hydrogen, respectively. represents an atom, a hydroxyl group, a halogen atom, or an alkyl group, and R_4 and R_5 each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or an NH
Represents Y. Y represents ▲There are numerical formulas, chemical formulas, tables, etc.▼ or -SO_2-R_7 (R_6 and R_7 each represent a hydrogen atom, an alkyl group, or an aryl group). However, at least one of R_1, R_2 and R_3
One is an alkoxy group. ) The other of Ar_1 and Ar_2 is selected from the groups represented by the following general formulas [B], [C], [D], [E], [F], or [G]. General formula [B] ▲ Numerical formulas, chemical formulas, tables, etc. N
Represents HY. Y represents ▲Numerical formula, chemical formula, table, etc.▼ or -SO_2-R_7 (R_6 and R_7 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 have the same meaning as 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).