JPS6130264B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor containing a bisazo compound (hereinafter referred to as a bisazo pigment).
More specifically, the present invention relates to a highly sensitive electrophotographic photoreceptor suitable for repeated use. Conventionally, electrophotographic photoreceptors having a photosensitive layer containing an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide as a main component are widely known. However, these are not necessarily satisfactory in terms of properties such as thermal stability and durability, and are also problematic in production and handling due to toxicity. On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, easy to handle, or are generally made of selenium photoreceptors. It has many advantages, such as superior thermal stability, and has attracted a lot of attention in recent years. Poly-N-vinylcarbazole is known as such an organic photoconductive compound, and poly-N-vinylcarbazole and 2,4,7-
Electrophotographic photoreceptors having a photosensitive layer mainly composed of a charge transfer complex formed with a Lewis acid such as trinitro-9-fluorenone have already been put into practical use. On the other hand, electrophotographic photoreceptors are known that have a laminated type or dispersed type functionally separated photosensitive layer in which the carrier generation function and the carrier transport function are assigned to separate substances, respectively.
For example, electrophotographic photoreceptors have been put into practical use that have a photosensitive layer that combines a carrier generation layer made of an amorphous selenium thin layer and a carrier transport layer made of poly-N-vinylcarbazole. Such functionally separated photoreceptors have a wide range of materials to choose from, and are thought to be able to meet various demands from electrophotographic processes, but they may have low electrophotographic sensitivity, high residual potential, or limited sensitivity wavelength range However, there are drawbacks such as the narrowness of the area, and nothing that fully satisfies these requirements has yet been obtained. Electrophotographic photoreceptors containing monoazo pigments or bisazo pigments as active ingredients are known as disclosed in JP-A-52-55643 and JP-A-54-2129. These azo pigments are effective in combination with certain carrier transport materials, but when combined with other carrier transport materials, sensitivity decreases and residual potential increases, making them difficult to meet the wide demands of electrophotographic processes. The reality is that we cannot answer this question. An object of the present invention is to provide an electrophotographic photoreceptor characterized by containing a bisazo pigment that is stable against heat and light and has excellent carrier generation ability. Another object of the present invention is to provide an electrophotographic photoreceptor having a carrier generating material comprising a bisazo pigment that is effective in combination with a wide variety of carrier transporting materials. Still another object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity and low residual potential. As a result of intensive research to achieve the above object, the present inventors have found the following general formulas [], [] and []
The present invention was completed based on the discovery that a bisazo pigment having an anthraquinone skeleton represented by the formula can serve as an excellent active ingredient for photoreceptors. [In the formula, A is

【formula】

【formula】

【formula】

【formula】

【formula】

[expression] or

[Formula], where n is 1 or 2, m is 0, 1 or 2, X is an amino group or hydroxy group, Y is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a carboxylic acid group, a sulfonic acid group , a substituted or unsubstituted carbamoyl group, and a substituted or unsubstituted sulfamoyl group, and Z is a hydrocarbon cyclic aromatic group such as a benzene ring or a naphthalene ring, a carbazole ring, a benzofuran ring, or an indole ring. Atom groups constituting heterocyclic aromatic rings or substituents thereof,
R ₁ is a hydrogen atom, a substituted or unsubstituted amino group, alkyl group, carbamoyl group, or carboxylic acid group or an ester group thereof, A ₁ is a substituted or unsubstituted aryl group, R ₂ and R ₃ are each substituted or unsubstituted represents an alkyl group, aralkyl group or aryl group. ) The present invention utilizes the excellent properties of the bisazo pigments represented by the general formulas [], [], and [] to provide an electrophotographic photoreceptor with excellent electrophotographic properties such as sensitivity and residual potential. It is in. General formula [] representing the bisazo pigment of the present invention,
A in [] and [] is shown in the above structural formula, but Y in the structural formula is particularly

A carbamoyl group of the formula [Formula] is preferred. R ₄ is preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group or an ethyl group, or an aryl group which may have a substituent. Further, A ₂ is preferably a substituted or unsubstituted carbocyclic aromatic ring, specifically a benzene ring,
Examples include naphthalene rings. Substituents bonded to these rings include nitro groups, cyano groups, carboxylic acid groups, sulfonic acid groups, halogen atoms such as chlorine atoms and bromine atoms, alkyl groups such as methyl groups and ethyl groups, methoxy groups, and ethoxy groups. An alkoxy group such as a dimethylamino group or a dimethylamino group is selected. R ₁ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, or an ethyl group;
Preferred are amino groups, dialkylamino groups such as dimethylamino groups, amino groups having substituents such as arylamino groups such as phenylamino groups, carbamoyl groups, carboxylic acid groups, and their methyl ester and ethyl ester groups. A ₁ represents a substituted or unsubstituted aryl group, and examples of substituents include a nitro group, a cyano group, a carboxylic acid group, a sulfonic acid group, a halogen atom, an alkyl group such as a methyl group or an ethyl group, a methoxy group, and an ethoxy group. An alkoxy group such as a dimethylamino group or a dimethylamino group is preferable. R ₂ and R ₃ each represent a substituted or unsubstituted alkyl group, aralkyl group, or aryl group, and specifically, methyl group, ethyl group, linear or branched propyl group, butyl group, etc. unsubstituted alkyl groups, hydroxyalkyl groups, alkoxyalkyl groups, acyloxyalkyl groups, alkyl groups with substituents such as alkylaminoalkyl groups, aralkyl groups such as benzyl groups and phenethyl groups, cyclopentyl groups, cyclohexyl groups, etc. a 5- to 7-membered cycloalkyl group,
5- to 7-membered cycloalkenyl groups such as cyclohexenyl groups, unsubstituted aryl groups such as phenyl groups,
Examples include aryl groups having substituents such as chlorophenyl group, methoxyphenyl group, and tolyl group. Hereinafter, the general formula [] used in the present invention,
Specific examples of the bisazo pigments represented by [ ] and [ ] are listed below, but the compounds of the present invention are not limited to these. The above bisazo pigments can be synthesized by known methods. That is, diaminoanthraquinone is diazotized with hydrochloric acid and sodium nitrite, hydroborofluoric acid is added thereto and isolated as a tetrazonium salt, and then diazotized with various couplers in the presence of an alkali in a solvent such as N.N-dimethylformamide. It can be easily manufactured by coupling. Next, a typical method for synthesizing the bisazo pigment used in the present invention will be specifically explained. Synthesis example (synthesis of exemplified compound (4)) 1,4-diaminoanthraquinone 23.8g (0.1
14.0 g (0.2 mole) of sodium nitrite dissolved in 20 ml of water was added dropwise at 5°C. After the dropwise addition is completed, the reaction solution is heated to 50°C to complete the reaction. Add 1 part of warm water and filter while still warm to make the filtrate.
Add 300 ml of 42% hydroborofluoric acid and filter the resulting precipitate. The crystals are washed with water, then washed with ethanol and ether, and dried to obtain 35.3 g (yield: 81%) of the tetrazonium salt. Next, 10.5 g (0.04 mol) of 2-hydroxy-3-naphthoic acid anilide (naphthol AS) was dissolved in 800 ml of N·N-dimethylformamide, and 8.7 g of tetrazonium salt was dissolved in 200 ml of N·N-dimethylformamide. After adding the dissolved material at a temperature of 10°C, add 20g of sodium acetate aqueous solution (150
ml) was slowly added dropwise, resulting in a reddish-purple precipitate. After the dropwise addition was completed, the mixture was stirred at room temperature for 1 hour and the precipitate was collected by filtration. This precipitate was washed with N・N-dimethylformamide, water, and finally ethanol, and then dried to give a total weight of 14.3 g.
A bisazo pigment (yield 91%) was obtained. Melting point over 300°.

[Table] From the above elemental analysis results and the appearance of absorption at ν=1680 cm (amide absorption) in the infrared absorption spectrum, it can be understood that the target substance was synthesized. The bisazo pigment of the present invention has photoconductivity, and when an electrophotographic photoreceptor is manufactured using the same, a photosensitive layer in which the bisazo pigment of the present invention is dispersed in a polymer binder is placed on a conductive support. It can be manufactured by providing. Another method is to use the bisazo pigment of the present invention as a carrier-generating substance utilizing only its particularly excellent carrier-generating ability among its photoconductivity properties, and to use it together with a carrier-transporting substance that can effectively act in combination with this. Accordingly, it is also possible to form a so-called functionally separated electrophotographic photoreceptor, which is a laminated type or a dispersed type. The electrophotographic photoreceptor of the present invention contains the above-mentioned bisazo pigment, and the bisazo pigment contains 1
It may be used not only as seeds but also as a mixture of two or more types. Various mechanical configurations of electrophotographic photoreceptors are known, and the photoreceptor of the present invention can take any of these forms. Usually, it is in the form shown in FIGS. 1 to 6. In FIGS. 1 and 3, a photosensitive layer is formed of a laminate of a carrier generation layer 2 containing the above-mentioned bisazo pigment as a main component and a carrier transport layer 3 containing a carrier transport substance as a main component on a conductive support 1. 4 will be provided. As shown in FIGS. 2 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, an electrophotographic 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 in which the carrier generating substance 7 is dispersed in a layer 6 containing a carrier transporting substance as a main component.
may be provided directly on the conductive support 1 or via an intermediate layer 5. Here, when the photosensitive layer 4 has a two-layer structure, it is possible to use either the carrier generation layer 2 or the carrier transport layer 3 as the upper layer, and the carrier transport layer 3 can also be used as a hole transfer medium for electrons. It can also be used as a transportation medium.
Electron transfer media include electron-accepting substances having electron-accepting groups such as cyano groups, nitro groups, and halogen atoms, such as tetracyanoquinodimethane, tetracyanoethylene, 2,4,7-trinitro-9-fluorenone, and tetracyanoquinodimethane. Examples include nitrofluorenone, trinitrotoluene, chloranylbromanil, and the like. In addition, as a hole transfer medium, electron-donating substances such as polymers having a side chain of a heterocyclic compound such as carbazole, triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, polyarylalkane compounds, and phenylenediamine derivatives are used. , hydrazone derivatives, amino-substituted chalcone derivatives, arylamine derivatives,
Examples include N.N-bical basil derivatives. However, the carrier transport materials used in the present invention are not limited to these. The bisazo pigment of the present invention constituting the photosensitive layer 4 having a two-layer structure can be applied directly onto the conductive support 1 or the carrier transport layer 3 as a carrier generation layer 2, or if necessary, as an intermediate layer such as an adhesive layer or a barrier layer. The layer can be formed by the following method. (1) Vacuum deposition method (2) A method in which a solution of a bisazo pigment dissolved in an appropriate solvent is mixed and dissolved with a binder as necessary. (3) A method in which a bisazo pigment is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a dispersion obtained by mixing and dispersing with a binder as necessary is applied. The solvent used in the method (2) above is n-
Examples include amines such as butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, and piperidine. The solvents used in method (3) include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, and xylene, and chlorinated hydrocarbons such as chloroform, dichloroethane, and methylene chloride. , ethers such as tetrahydrofuran and dioxane, alcohols such as methanol, ethanol and isopropanol, esters such as ethyl acetate and butyl acetate, and aprotic polar solvents such as N.N-dimethylformamide and dimethyl sulfoxide. The thickness of the carrier generation layer 2 thus formed is preferably 0.01 to 20 μm, more preferably 0.05 to 5 μm. In addition, the particle size of the bisazo pigment in the case of applying the dispersion system in (3) above is 5 μm.
m or less, more preferably 1
It is less than μm. When using a binder, 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. Examples of such high molecular weight polymers include, but are not limited to, the following. (1) Polycarbonate (2) Polyester (3) Methacrylic resin (4) Acrylic resin (5) Polyvinyl chloride (6) Polyvinylidene chloride (7) Polystyrene (8) Polyvinyl acetate (9) Styrene-butadiene copolymer (10) ) Vinylidene chloride-acrylonitrile copolymer (11) Vinyl chloride-vinyl acetate copolymer (12) Vinyl chloride-vinyl acetate-maleic anhydride copolymer (13) Silicone resin (14) Silicone-alkyd resin (15) Phenol -Formaldehyde resin (16) Styrene alkyd resin (17) Poly-N-vinylcarbazole These binders can be used alone or as a mixture of two or more. The conductive support 1 used in the construction of the electrophotographic photoreceptor of the present invention is a metal plate, a conductive polymer, a conductive compound such as indium oxide, or a thin metal layer such as aluminum, palladium, gold, etc. Paper, plastic film, etc. that have been made conductive by coating, vapor depositing, or laminating are used. The intermediate layer 5 such as an adhesive layer or a barrier layer may include gelatin, casein, starch, in addition to the high molecular weight polymer used as the binder.
Organic polymer substances such as polyvinyl alcohol, ethyl cellulose, and carboxymethyl cellulose, or aluminum oxide are used. The electrophotographic photoreceptor of the present invention has the above-mentioned structure, and as is clear from the examples described later,
It has excellent charging characteristics, sensitivity characteristics, and image forming characteristics. Examples of the present invention will be specifically described below, but the embodiments of the present invention are not limited thereby. Example 1 A 2% ethylenediamine solution of exemplified compound (4) was
A carrier generation layer was formed by coating onto a polyester film laminated with aluminum so that the dry film thickness was 0.5 μm. Furthermore, 1-phenyl-3- is added thereon as a carrier transport layer.
(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline 10g and polycarbonate resin (Teijin Kasei Panlite L-
A solution prepared by dissolving 14 g of 1250) in 140 ml of dichloromethane was applied and dried to a dry film thickness of 12 μm. The photoreceptor obtained as described above was subjected to the following characteristic evaluations using an electrostatic paper tester model SP-428 manufactured by Kawaguchi Electric Seisakusho Co., Ltd. When charged for 5 seconds at a charging voltage of -6 KV, the surface potential (V ₀ ) was -1180V. After this was left in the dark for 5 seconds, the surface potential (V ₁ ) was -1020V.
This is irradiated with halogen lamp light, and the exposure amount required to attenuate the surface potential by half (half-reduction exposure amount E
1/2), it was 3.2 lux・sec. Further, the residual potential V _R was 0V. Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that Exemplified Compound (4) was replaced with Exemplified Compound (7), and the half-decrease exposure was measured in the same manner as in Example 1, and it was found to be 3.4 lux・sec
It was hot. Further, the residual potential V _R was 0V. Example 3 2 g of Exemplified Compound (12) and 2 g of polycarbonate resin (Panlite L-1250) were mixed in dichloromethane.
The mixture was added to 100 ml and dispersed in a ball mill for 12 hours. This liquid was applied onto a polyester film on which aluminum was vapor-deposited so that the dry film thickness would be 2 μm to form a carrier generation layer, and then 6 g of tri-p-tolylamine and a polyester resin (Toyobo Co., Ltd.) Pylon 200) 10g and dichloroethane
A solution dissolved in 120 ml was applied to give a dry film thickness of 12 μm and dried. The half-decrease exposure amount of this photoreceptor was measured in the same manner as in Example 1, and it was 4.7.
It was lux・sec. Further, the residual potential V _R was -5V. Example 4 A photoreceptor was prepared in the same manner as in Example 3 except that Exemplified Compound (12) was replaced with Exemplified Compound (34).
When I measured the half-life exposure in the same way as above, it was 4.6 lux・
It was hot in sec. Further, the residual potential V _R was -5V. Example 5 A photoreceptor was prepared in the same manner as in Example 3 except that Exemplified Compound (12) was replaced with Exemplified Compound (47), and it was transferred to an electronic copying machine U-Bix2000R (manufactured by Nishiroku Photo Industry Co., Ltd.).
When the image was copied using a 3D printer (manufactured by Fujitsu Co., Ltd.), a copy with high contrast, faithful to the original, and clear was obtained. This did not change even after repeating this 2000 times. Example 6 1,1-bis(4-
N・N-dibenzylaminophenyl)butane 10g
and polycarbonate resin (Panlite L-1250)
A solution of 14 g dissolved in 150 ml of dichloroethane was applied so that the dry film thickness was 10 μm. Furthermore, as a carrier generation layer, an ethylenediamine solution of exemplified compound (18) was added to
It was applied to a thickness of 0.5 μm and dried. The photoreceptor thus obtained has a sensitivity of 6.4 lux・sec when positively charged.
It was hot. Further, the residual potential V _R was +8V. Example 7 A polyester resin (Vylon manufactured by Toyobo Co., Ltd.) was applied onto a polyester film on which aluminum was vapor-deposited.
200) 10g, 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole 5
g, 3 g of Exemplified Compound (10) in tetrahydrofuran
In addition to 100 ml of the dispersion, a dispersion solution that was dispersed in a ball mill for 12 hours was coated to a dry film thickness of 8 μm to prepare a photoreceptor having a single layer structure. The half-decreased exposure amount of this photoconductor was measured in the same manner as in Example 6, and it was 5.0.
It was lux・sec. Further, the residual potential V _R was +5V. Example 8 5 g of exemplified compound (40) and 3.3 g of polycarbonate resin (Panlite L-1250) were mixed in dichloromethane.
A 0.05 μm thick medium made of vinyl chloride-maleic anhydride copolymer "Ezuretsuk MF-10" (manufactured by Sekisui Chemical Co., Ltd.) was prepared by dispersing the dispersion liquid in a ball mill for 24 hours on a polyester film coated with aluminum. A photoreceptor was prepared by forming a layer and then coating the film to a dry film thickness of 10 μm. When the photoreceptor obtained as described above is positively charged (charging voltage +6KV for 5 seconds), the half-reduced exposure amount is 6.2
It was lux・sec. Further, the residual potential V _R was +20. Comparative Example 1 Exemplary compound (4) was used as a carrier generating substance with the following bisazo compound. A comparative photoreceptor was prepared in the same manner as in Example 1, except that . The residual potential was -31V. Comparative Example 2 Exemplary compound (12) was replaced with the following compound. A comparative photoreceptor was prepared in the same manner as in Example 3, except that . The residual potential was -49V. Comparative Example 3 Exemplary compound (12) was replaced with the following bisazo compound. A comparative photoreceptor was prepared in the same manner as in Example 3, except that the following was used: When images were copied from this in the same manner as in Example 5, only copies with a lot of fog were obtained. Comparative example 4 Exemplary compound (40) A comparative photoreceptor was prepared in the same manner as in Example 8, except that . The residual potential was +80V. As described above, the electrophotographic photoreceptor containing the bisazo compound of the present invention is an excellent electrophotographic photoreceptor with higher sensitivity and lower residual potential than comparative photoreceptors.

[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 a carrier transport substance, 7
...Carrier generating substance.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing at least one bisazo compound represented by the following general formulas [], [], and [] on a conductive support. [In the formula, A is [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] or [Formula], where n is 1 or 2, m is 0, 1 or 2, and X is an ami) group or a hydroxy group, Y is selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a carboxylic acid group, a sulfonic acid group, a substituted or unsubstituted carbamoyl group, and a substituted or unsubstituted sulfamoyl group,
Z is an atomic group constituting a carbocyclic aromatic ring, a heterocyclic aromatic ring, or a substituted product thereof, R ₁ is a hydrogen atom, a substituted or unsubstituted amino group, an alkyl group, a carbamoyl group, a carboxylic acid group, or an ester thereof The group A ₁ represents a substituted or unsubstituted aryl group, and R ₂ and R ₃ each represent a substituted or unsubstituted alkyl group, aralkyl group, or aryl group. [2] The photosensitive layer is composed of a laminate of a carrier generation layer containing a carrier generation substance and a carrier transport layer containing a carrier transport substance, and the bisazo compound is present in at least the carrier generation layer and/or the carrier transport layer. The electrophotographic photoreceptor according to claim 1, which is contained in one layer. 3. The electrophotographic photoreceptor according to claim 1 or 2, wherein the photosensitive layer is a layer containing a mixture of a carrier generating substance, a carrier transporting substance, and the bisazo compound.