JPH0452461B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly to a photoreceptor having a photosensitive layer containing an azo pigment using a 2-hydroxy-11H-benzo[a]carbazole-3-carbohydrazide derivative. Conventional technology Conventionally, amorphous selenium,
Inorganic photoconductive materials such as selenium alloys, cadmium sulfide, and zinc oxide, polyvinyl carbazole, and derivatives thereof are widely known. It is well known that amorphous selenium or selenium alloys have extremely excellent properties as electrophotographic photoreceptors and are widely used in practical use. However, the sensitive wavelength region of amorphous selenium is the blue region and has almost no sensitivity in the red region. Various methods have been proposed to extend the photosensitivity to long wavelengths, but there are many restrictions on the selection of the sensitive wavelength range, and the photosensitivity to long wavelengths is not sufficient. Even when zinc oxide or cadmium sulfide is used as a photoreceptor, its sensitivity wavelength range is narrow, and it is necessary to add various sensitizers for practical use. Polyvinylcarbazole, which is widely known as an organic photoconductive material, is excellent in terms of transparency, film-forming properties, flexibility, positive hole transport, etc., but polyvinylcarbazole itself has a visible light range of 400 to 700 nm.
has the disadvantage of having almost no sensitivity. To improve these shortcomings, the Special Public Service was developed in the 1970s.
No. 10496 describes polyvinylcarbazole and 2,4,
A photoreceptor is disclosed in which a charge transfer complex is formed with 7-trinitrofluorenone. In addition, as a photoreceptor in which amorphous selenium or selenium alloy is used as a charge generation layer and a charge transfer layer is laminated on this, each layer has a role.
-5349 Publication, Special Publication No. 1977-3168, Special Publication No. 1973
-14914, Japanese Patent Publication No. 51-10982, etc. In addition, the following photoreceptors have been developed in which a charge-generating layer is made of various pigments and a charge-transfer layer is provided thereon. USP 3837851 describes a photoreceptor having a charge generation layer and a charge transfer layer containing at least one triallylpyrazoline; USP 3850630 describes a photoreceptor comprising a transparent charge transfer layer and a charge generation layer comprising an indigoid pigment; A photoreceptor is disclosed that includes a charge generation layer made of a perylene pigment derivative and a charge transfer layer made of a condensate of 3-bromopyrene and formaldehyde. Although some of these photoreceptors are already in use on the market, the current situation is that a photoreceptor that satisfactorily satisfies various properties has not yet been obtained. Purpose The present invention was made in order to solve the problems of the prior art as described above, and an object of the present invention is to provide a photoreceptor having high sensitivity and excellent flexibility. Composition As a result of various studies, the present inventor has found that a compound represented by the general formula below works effectively as a charge generating substance for an electrophotographic photoreceptor, and has completed the present invention. That is, the electrophotographic photoreceptor of the present invention has the general formula () [In the formula, X: represents a hydrocarbon aromatic ring group which may have a substituent or a heteroaromatic ring group which may have a substituent, R ₁ , R ₂ : hydrogen, lower alkyl group, substituted represents a hydrocarbon aromatic ring group which may have a group or a heteroaromatic ring group which may have a substituent, and at least one of R ₁ and R ₂ is an aromatic ring, and further,
R ₁ and R ₂ may jointly form a ring. n: represents an integer of 1, 2 or 3. ] It is characterized by having a photosensitive layer containing an azo pigment represented by the following. As X in the general formula (), benzene,
Hydrocarbon aromatic rings such as naphthalene, fluorene, atracene, anthraquinone, and pyrene; heteroaromatic ring groups such as furan, thiophene, pyridine, indole, benzothiazole, carbazole, acridone, and dibenzothiophene; linked with aromatic or non-aromatic groups, such as triphenylamine, biphenyl, terphenyl, binaphthyl, diphenyloxadiazole, biphenyl sulfone, diphenylmethane, diphenyl ether, stilbene, distyrylbenzene, distyryl Examples include carbazole, distyrylanthracene, dibenzylideneketopiperazine, and the like. Substituents for these rings include lower alkyl groups such as methyl and ethyl groups, lower alkoxy groups such as methoxy and ethoxy groups, dialkylamino groups such as dimethylamino and diethylamino groups, and halogen atoms such as chlor and bromine. , hydroxy group, nitro group, cyano group, halomethyl group, etc. Specific examples of the azo pigment of general formula () include the following. However, for the sake of simplicity, only the structure and substitution position of X are shown. (A) When n=3 (trisazo compound)

[Table] (B) When n=2 (disazo compound)

【table】

【table】

【table】

【table】

[Table] (C) When n=1 (monoazo compound)

【table】

[Table] Furthermore, specific examples of R ₁ and R ₂ in general formula () include lower alkyl groups such as methyl group, ethyl group, butyl group, benzene ring, naphthalene ring,
Hydrocarbon aromatic rings such as anthracene ring and pyrene ring, heteroaromatic rings such as pyridine ring, furan ring, thiophene ring, indole ring, carbazole ring, and dibenzofuran ring are also examples of substituents for these aromatic rings. Examples of the group include a lower alkyl group, a lower alkoxy group, a dialkylamino group, a dialkylamino group, a halogen, a hydroxy group, a nitro group, a cyano group, and a halomethyl group. To obtain the azo pigments of the invention, the corresponding amino derivatives are diazotized or further isolated, for example as tetrafluoroborate salts, and then the corresponding coupling component, i.e. 2-hydroxy-
11H-Benzo[a]carbazole-3-carbohydrazide derivative It can be easily produced by reacting a suitable organic solvent with a base in, for example, N,N-dimethylformamide to perform a coupling reaction. The electrophotographic photoreceptor according to the present invention is shown in FIGS.
It can take the form of a figure. The photoreceptor shown in FIG. 1 has a laminated photosensitive layer 2 on a conductive support 1, which is composed of a charge generation layer 5 mainly containing an azo pigment 3 and a charge transfer layer 6 mainly containing a charge transfer substance. It is something that In the photoreceptor shown in FIG. 1, imagewise exposed light passes through the charge transfer layer and reaches the charge generation layer 5, where the azo pigment 3 generates charges, while the charge transfer layer 6 The charge required for light attenuation is generated by the azo pigment 3.
Also, the mechanism of charge movement is in the charge transfer layer 6. The photoreceptor shown in FIG. 2 has a photosensitive layer 2' mainly composed of an azo pigment 3, a charge transfer substance, and an insulating binder on a conductive support 1. The photoreceptor shown in FIG. Again, the azo pigment 3 is a charge generating substance. For other photoreceptors, it is also possible to reverse the charge generation layer and the charge transfer layer shown in FIG. The thickness of the photosensitive layer 2 is as shown in FIG. 1, and the thickness of the charge generation layer 5 is preferably 0.01 to 5μ, more preferably
It is 0.05~2μ. If the thickness is less than 0.01μ, charge generation will not be sufficient, and if it is more than 5μ, the residual potential will be too high for practical use. Charge transfer layer 6
The thickness is preferably 3 to 50μ, more preferably 5 to 20μ. If the thickness is less than 3μ, the amount of charge will be insufficient, and if it is more than 50μ, the residual potential will be too high to be practical. The charge generation layer 5 is mainly composed of an azo pigment represented by the above general formula, and may further contain a binder, a plasticizer, and the like. Also,
The proportion of the azo pigment in the charge generating layer is preferably 30% by weight or more, more preferably 50% by weight or more. The charge transfer layer 6 is mainly composed of a charge transfer substance and a binder, and may further contain a plasticizer. The proportion of charge transfer material in the charge transfer layer is 10-95
% by weight, preferably 30-90% by weight. When the proportion of the charge transfer substance is less than 10% by weight, almost no charge transfer takes place, and when it is more than 95% by weight, the mechanical strength of the photoreceptor film is so poor that it cannot be put to practical use. In the case of the photoreceptor shown in FIG. 2, the thickness of the photosensitive layer 2' is preferably 3 to 50 μm, more preferably 5 μm.
~20μ. Further, the proportion of the azo pigment in the photosensitive layer 2' is preferably 50% by weight or less, more preferably 20% by weight or less, and the proportion of the charge transfer substance is preferably 10 to 95% by weight, more preferably 30% by weight or less.
~90% by weight. The gist of the present invention is to use a specific azo pigment represented by the above general formula as a charge generating substance in an electrophotographic photoreceptor, and other components such as a conductive support and a charge transfer substance are used. Any of those conventionally known can be used, and these will be specifically explained below. The conductive support used in the photoreceptor of the present invention may be a metal plate made of aluminum, copper, zinc, etc., a plastic sheet made of polyester, or a plastic film on which a conductive material such as aluminum or SnO ₂ is vapor-deposited, or a conductive support material such as aluminum, SnO2, etc. Treated paper, etc. is used. As a binder, polyamide, polyurethane,
Examples include condensation resins such as polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide, but all resins that are insulating and adhesive can be used. Can be used. Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. In addition, silicone oil or the like may be added to improve the surface properties of the photoreceptor. Examples of charge transfer substances include vinyl polymers such as poly-N-vinylcarbazole, polyvinylindoquinoxanoline, polyvinylbenzothiophene, polyvinylanthracene, and polyvinylacridine, bromopyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, etc. Condensation resins such as 2,4,7-trinitro-
9-fluorenone, 2,6,8-trinitro-
4H-indeno[1,2-b]thiophene-4-
one, 2,8-dinitrodibenzothiophene,
1,3,7-trinitrodibenzothiophene-
5,5-dioxide, 1,3,7,9-tetranitrobenzo[c]cinnoline, 5-oxide, 2,4,8-trinitrothioxanthone, 1
-Brompyrene, N-ethylcarbazole, 2-
Phenylindole, 2-phenylnaphthalene,
2,5-bis(4-diethylaminophenyl)-
1,3,4-oxadiazole, 2,5-bis(4-diethylaminophenyl)-1,3,4-triazole, 1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylamino phenyl)pyrazoline, 2-phenyl-4-(4-diethylaminophenyl)-5-phenyloxazole, triphenylamine, tris(4-diethylaminophenyl)methane, 3,6-bis(dibenzylamino)- 9-ethylcarbazole, 1,
Examples include 1-bis(4-dibenzylaminophenyl)propane, 9-ethyl-3-carbazolaldehyde-1-methyl-1-phenylhydrazone, and the like. These charge transfer substances may be used alone or in a mixture of two or more. In any of the photoreceptors obtained as described above, an adhesive layer or a barrier layer may be provided between the conductive support and the photosensitive layer, if necessary. Suitable materials for these layers include polyamide, nitrocellulose, and aluminum oxide.
Further, the film thickness is preferably 1 μm or less. To create the photoreceptor shown in FIG. 1, an azo pigment is vacuum deposited on a conductive support using the vacuum deposition method described in USP 3973959, USP 3996049, etc.
Alternatively, if necessary, fine particles of azo pigment are dispersed in a suitable solvent in which a binder is dissolved, and this is coated and dried on a conductive support. After finishing the surface by a method such as buffing as described above, or adjusting the film thickness, a solution containing a charge transfer substance and a binder is applied and dried. The photoreceptor shown in FIG. 2 can be prepared by dispersing fine particles of an azo pigment in a solution containing a charge transfer substance and a binder, and applying and drying this onto a conductive support. In either case, the azo pigment used in the present invention is used after being ground to a particle size of 5 μm or less, preferably 2 μm or less, using a ball mill or the like. Application may be carried out by conventional means, such as a doctor blade, dipping, wire bar, etc. Effects To perform copying using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed, and then developed.
This can be accomplished by transferring to paper, etc., if necessary. The photoreceptor of the present invention has excellent advantages such as high sensitivity and flexibility. Examples are shown below. Example 1 Compound No. 1 (R ₁ :

[Formula], R ₂ : H) 2 parts by weight of the azo pigment and 98 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto an aluminum-deposited polyester film with a doctor blade and air-dried. A charge generation layer having a thickness of 1 μm was formed. On the other hand, 9-(4
-diethylaminostyryl) anthracene and polycarbonate resin (manufactured by Teijin Co., Ltd.,
Panlite L]2 resin part, tetrahydrofuran
This was dissolved in 16 parts by weight and applied onto the charge generation layer using a doctor blade, and dried at 120°C for 10 minutes to form a charge transfer layer with a thickness of 20μ, thereby obtaining the laminated photoreceptor shown in Figure 1. . Next, a -6KV corona discharge was applied to the photosensitive layer surface of this photoreceptor using a commercially available electrostatic copying paper tester for 20 seconds to negatively charge it, and then it was left in a dark place for 20 seconds. ), then irradiate the photosensitive layer with light from a tungsten lamp so that the surface has an illuminance of 20 lux, find the time (seconds) until the surface potential becomes 1/2 of Vpo, and calculate the halved exposure amount. It was set as E1/2 (lux seconds). The result was Vpo 927 volts E1/2 2.0 lux seconds. Example 2 Compound No. 1 (R ₁ :

[Formula] R ₂ :H) 1 part by weight of an azo pigment and 66 parts by weight of a 0.5% by weight tetrahydrofuran solution of polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) were pulverized and mixed in a ball mill, and the resulting dispersion was mixed. The solution was applied using a doctor blade onto a polyester film on which aluminum had been vapor-deposited, and dried at 80° C. for 2 minutes to form a charge generation layer with a thickness of 0.7 μm. Separately, 2 parts by weight of 1,1-bis(4-dibenzylaminophenyl)propane and 2 parts by weight of polycarbonate resin (Panlite K-1300 manufactured by Tenjin Co., Ltd.) were dissolved in 16 parts by weight of tetrahydrofuran, and the mixture was dissolved in 16 parts by weight of tetrahydrofuran. It was applied onto the charge generation layer using a doctor blade and dried at 120°C for 10 minutes to form a charge transfer layer with a thickness of 13μ, thereby obtaining the laminated photoreceptor shown in FIG.
Next, E1/2 was determined in exactly the same manner as in Example 1. E1/2=3.2 (lux·sec) Examples 3 to 5 The same procedure was carried out as shown in Figure 1, except that each azo pigment shown in Table 1 below was used instead of the azo pigment used in Example 2. A photoreceptor was prepared and E1/2 was determined using the same method, and the results shown in Table 1 were obtained.

[Table] Example 6 Compound No. 14 (R ₁ :

[Formula] R ₂ :H) 2 parts by weight of the azo pigment and 70 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto an aluminum-deposited polyester film using a doctor blade. It was dried to form a charge generating layer with a thickness of 1.5 microns. On the other hand, 2 parts by weight of 1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline and 3 parts by weight of polystyrene (Toborex, manufactured by Mitsui Toatsu Chemical Co., Ltd.) were added to 17 parts by weight of tetrahydrofuran. Dissolve and apply this onto the charge generation layer using a doctor blade, and heat at 120°C.
The mixture was dried for 10 minutes to form a charge transfer layer with a thickness of 19 μm, thereby obtaining the laminated photoreceptor shown in FIG. Next, E1/2 was determined in exactly the same manner as in Example 1. E1/2 (lux·sec) = 1.8 Examples 7 to 10 Instead of the azo pigment used in Example 6,
The photoreceptor shown in FIG. 1 was prepared using the same procedure except that each of the azo pigments shown in Table 2 below was used. E1/2 was determined in the same manner, and the results shown in Table 2 were obtained.

[Table] Example 11 Compound No. 1 (R ₁ :

[Formula] R ₂ : H) 2 parts by weight of the azo pigment and 98 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto an aluminum-deposited polyester film with a doctor blade and air-dried. A charge generation layer having a thickness of 1 μm was formed. On the other hand, 2 parts by weight of 9-ethyl-3-carbazolaldehyde 1-methyl-1-phenylhydrazone, 1 part by weight of poly-N-vinylcarbazole (manufactured by BASF - Rubican M-170) and polyester resin (Example 2) 1 part by weight of the same) was dissolved in 18 parts by weight of tetrahydrofuran, and this was applied onto the charge generation layer using a doctor blade, and dried at 120°C for 10 minutes to form a charge transfer layer with a thickness of 23 μm. A laminated photoreceptor was obtained. Next, E1/2 was determined in exactly the same manner as in Example 1. E1/2 = 0.9 (lux/second) Examples 12 to 15 The same procedure as shown in Figure 1 was carried out except that each azo pigment shown in Table 3 below was used instead of the azo pigment used in Example 11. A photoreceptor was prepared and E1/2 was determined using the same method, and the results shown in Table 3 were obtained.

[Table] Example 16 10 parts by weight of polyester resin (same as Example 2), 10 parts by weight of 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole,
Compound No. 32 (R ₁ :

[Formula] 2 parts by weight of the azo pigment represented by R ₂ :H) and 108 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was placed on a polyester film coated with aluminum using a doctor blade. Apply and dry at 120℃ for 10 minutes to achieve thickness
A photoreceptor having the form of FIG. 2 having a 14 μm photosensitive layer was prepared. Hereinafter, the same measurements as in Example 1 were carried out for this photoreceptor except that a +6 KV corona discharge was used to determine E1/2. E1/2 = 2.9 (lux seconds) Examples 17 to 20 The same procedure as shown in Figure 2 was carried out except that each azo pigment shown in Table 4 below was used instead of the azo pigment used in Example 16. A photoreceptor was prepared, and E1/2 was determined using the same method, and the results shown in Table 4 were obtained.

【table】 [Brief explanation of the drawing]

1 and 2 are enlarged sectional views of the photoreceptor of the present invention, respectively. 1... Conductive support, 2, 2'... Photosensitive layer, 3
... Azo pigment, 4 ... Charge transfer medium, 5 ... Charge generation layer, 6 ... Charge transfer layer.

Claims (1)

[Claims] 1 General formula () [In the formula, X: represents a hydrocarbon aromatic ring group which may have a substituent or a heteroaromatic ring group which may have a substituent, R ₁ , R ₂ : hydrogen, lower alkyl group, substituted represents a hydrocarbon aromatic ring group which may have a group or a heteroaromatic ring group which may have a substituent, and at least one of R ₁ and R ₂ is an aromatic ring, and further,
R ₁ and R ₂ may jointly form a ring. n: represents an integer of 1, 2 or 3. ] An electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo pigment represented by: