JPS6129497B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photoreceptor for electrophotography, and more particularly to a novel photoreceptor having a photosensitive layer containing a monoazo pigment as an active ingredient. Conventionally, electrophotographic photoreceptors in which a photosensitive layer containing an azo pigment as an active ingredient is provided on a conductive support have been used, for example, photoreceptors using monoazo pigments (Tokuko Showa).
44-16474) and one using a benzidine-based disazo pigment (Japanese Unexamined Patent Publication No. 47-37543) are known. These azo pigments are certainly useful materials as active ingredients in photosensitive layers, but considering the various requirements for photoreceptors from the point of view of electrophotographic processes, no one has yet been obtained that fully satisfies these requirements. The reality is that there is not. Therefore, it is even more important to have a wide variety of pigments that can be used as active ingredients, not just azo pigments, and only then can we provide photoreceptors suitable for certain processes. becomes possible.
That is, in the electrophotographic process, it is desirable to have as many types of pigments as possible that can act as active ingredients in the photoreceptor. A first object of the present invention is to provide an electrophotographic photoreceptor containing a novel monoazo pigment that can serve as an active ingredient in various electrophotographic processes. A second object of the present invention is to provide an electrophotographic photoreceptor that allows a wide selection of monoazo pigments that can serve as active ingredients. A third object of the present invention is to provide a highly sensitive and highly flexible electrophotographic photoreceptor containing a novel monoazo pigment. The present inventors produced a group of monoazo pigments and studied their application to photoreceptors, and as a result, they found that monoazo pigments having a styrylpyrene skeleton represented by the general formula below can serve as an excellent active ingredient for photoreceptors. This knowledge led to the completion of the present invention. That is, the present invention provides a structure in which the general formula [However, A is

【formula】

【formula】 or

[ _{Formula ] (} where _,
R ₃ represents hydrogen, a lower alkyl group, a phenyl group, or a substitute thereof; R ₂ represents a lower alkyl group, a carboxyl group, or an ester thereof. ) There is provided an electrophotographic photoreceptor characterized by having a photosensitive layer containing a monoazo pigment represented by the following formula. In the above general formula, specific examples of X include a benzene ring, a naphthalene ring, an indole ring, a carbazole ring, a benzofuran ring, or a substituted product thereof (for example, a halogen substituted product). Specific examples of Ar ₁ include benzene ring, naphthalene ring, dibenzofuran ring, carbazole ring, or substituents thereof (e.g., halogen, C ₁ to C ₄ alkyl, C ₁ to _{C 4} alkoxy, each alkyl C ₁ to _{C 4} dialkylamino, diano, carboxyl, nitro, or sulfonyl substituted products). Specific examples of Ar ₂ and Ar ₃ include benzene rings, naphthalene rings, and substituents thereof (e.g., nitro, sulfamino, sulfonyl, halogen, C ₁ to _{C 4} alkyl, C ₁ to _{C 4} carboxyl, cyano, each alkyl is _C1 - _C4 dialkylamino, or alkyl is _C1 - _C4 acylamino substituted product). R ₁ , R ₂ and
As the lower alkyl group for R ₃ , a C ₁ -C ₄ group is suitable. Further, examples of substituents for the phenyl group in R ₁ and R ₃ include halogen substituents. Furthermore
The carboxylic acid ester group in R ₂ is C ₁ -
_C4 is suitable. Next, specific examples of compounds having the above general formula used in the present invention are shown by structural formulas. These monoazo pigments are prepared by first diazotizing 1-(4-aminostyryl)pyrene and isolating it as a tetrazonium salt, which is then dissolved in a suitable organic solvent such as N,N-dimethylformamide corresponding to each of the pigments mentioned above. It can be easily produced by a coupling reaction in the presence of a coupler and alkali. For example, the method for producing pigment No. 1 is as follows. Note that other monoazo pigments can be produced according to this production example, except for changing the coupler. Production example 22.0g of 1-(4-aminostyryl)pyrene,
Add to dilute hydrochloric acid prepared from 150 ml of concentrated hydrochloric acid and 150 ml of water and stir well at 60°C for about 30 minutes. Next, this mixture was cooled to about 0°C, and a solution of 6.0 g of sodium nitrate dissolved in 30 ml of water was added at a temperature of -1 to 0°C for about 30 minutes.
Drip over a period of minutes. After that, stir at the same temperature for about 30 minutes, remove a small amount of unreacted material, and reduce the liquid to 42%.
Pour into 30 ml of borofluoric acid, collect precipitated crystals, wash with water, and dry to obtain 26.7 g (yield: 92%) of red crystals of tetrazonium fluoroborate. Decomposition point approximately 135℃. Next, 2.0g of the tetrazonium salt obtained in this way
and 1.4 g of 2-hydroxy-3-naphthoic acid anilide as a coupler were dissolved in 200 ml of cooled N,N-dimethylformamide, and 4 g of a solution consisting of 2.4 g of sodium acetate and 30 ml of water was added to the solution.
After dropwise addition over a period of 1 hour at a temperature of ˜8° C., it is stirred at room temperature for about 3 hours. After that, remove the precipitate,
Wash three times with 300 ml of water and then eight times with 300 ml of N,N-dimethylformamide. Furthermore, the remaining N,N-dimethylformamide was washed away with acetone, and the resulting blue-black crystals were dried at a temperature of 70°C under a reduced pressure of 2 mmHg to obtain No. 1 monoazo pigment.
Obtain 2.5 g (91% yield). Melting point over 250℃. Elemental analysis calculated value Actual value C (%) 82.94 82.79 H (%) 4.59 4.60 N (%) 7.08 7.02 IR absorption spectrum (KBr tablet) 1680 cm ^-1 (secondary amide) The photoreceptor of the present invention is as described above. However, depending on how these pigments are applied, they can take the forms shown in Figures 1 to 3. The photoreceptor of FIG.
A photosensitive layer containing three resin binders is provided. Second
The photoreceptor in the figure has a monoazo pigment 4 on a conductive support 1.
(here used as charge carrier generating material)
-A charge transfer medium (a mixture of a charge transfer substance and a resin binder) 5-based photosensitive layer 2' is provided.
The photoreceptor shown in Figure 3 is a modification of the photoreceptor shown in Figure 2.
The photosensitive layer 2'' consists of a charge carrier generation layer 6 mainly composed of a monoazo pigment 4 and a charge transport medium layer 7. In the photoreceptor shown in FIG. The generation and transfer of the necessary charge carriers takes place via the pigment particles.
In the case of the photoreceptor shown, the charge transporting material together with the binder (and optionally the plasticizer) forms the charge transporting medium, while the monoazo pigment acts as the charge carrier generating material. Although this charge transfer medium does not have the ability to generate charge carriers like monoazo pigments, it has the ability to accept and transfer charge carriers generated from monoazo pigments. That is, in the photoreceptor of FIG. 2, the generation of charge carriers necessary for light attenuation is performed by a monoazo pigment, while the transfer of charge carriers is primarily performed by a charge transfer medium. Here, a further basic condition required of the charge transport medium is that the absorption wavelength region of the charge transport medium does not overlap with the absorption wavelength region of the monoazo pigment, which is mainly in the visible region. This is because in order to efficiently generate charge carriers in the monoazo pigment, it is necessary to transmit light to the surface of the pigment. However, this is not the case, for example, in the case of a photoreceptor that is sensitive only to a certain specific wavelength. Therefore, the absorption wavelengths of both the charge transfer medium and the monoazo pigment need not completely overlap. Next, in the photoreceptor shown in FIG. 3, the light that has passed through the charge transfer medium layer reaches the photosensitive layer 2'', which is the charge carrier generation layer, and charge carriers are generated in the monoazo pigment in that part. The charge transfer medium layer receives charge carriers and transfers them. The mechanism in which the charge carriers necessary for light attenuation are generated by the monoazo pigment and the charge carriers are transferred by the charge transfer medium is shown in Figure 2. This is the same as in the case of the photoreceptor shown. Again, the monoazo pigment is the charge carrier generating material. To prepare the photosensitive layer of Figure 1, fine particles of the monoazo pigment are dispersed in a binder solution to make them conductive. All you have to do is coat it on a support and dry it.To make the photoreceptor shown in Figure 2, fine particles of a monoazo pigment are dispersed in a solution containing a charge-transferable substance and a binder, and the particles are similarly coated on a conductive support. The photoreceptor shown in Figure 3 can be prepared by vacuum-depositing a monoazo pigment onto a conductive support, or by dispersing fine particles of a monoazo pigment in a suitable solvent in which a binder is dissolved if necessary. Then, this is coated on a conductive support and dried, and if necessary, the surface is finished by buffing or other methods or the film thickness is adjusted, and then a solution containing a charge-transfer substance and a binder is applied on top of the surface. In any case, the monoazo 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.
The application method is the usual method, such as doctor blade,
Do this with a wire bar, etc. The thickness of the photosensitive layer in FIGS. 1 and 2 is about 3 to 50 microns, preferably 5 to 20 microns. Further, in the case of FIG. 3, the thickness of the charge carrier generation layer is preferably 5 microns or less, preferably 2 microns or less, and the thickness of the charge transport medium layer is about 3 to 50 microns, preferably 5 to 20 microns. In addition, in the photoreceptor shown in Figure 1, the appropriate proportion of the monoazo pigment in the photosensitive layer is 30 to 70% by weight, preferably about 50% by weight (as mentioned above, in the case of the photoreceptor shown in Figure 1 Since the monoazo pigment acts as a photoconductive substance and the generation and transfer of charge carriers necessary for light attenuation occur through the pigment particles, the contact between the pigment particles must be continuous from the surface of the photosensitive layer to the support. is desirable.
For this reason, the proportion of pigment in the photosensitive layer is preferably as large as possible, but considering the strength and sensitivity of the photosensitive layer, it is approximately 50%.
weight%). In the photoreceptor shown in Figure 2, the proportion of the monoazo pigment in the photosensitive layer is 50% by weight or less,
It is preferably 20% by weight or less, and the proportion of the charge-transferable substance is 10 to 95% by weight, preferably 30 to 90% by weight. Further, the proportion of the charge transporting substance in the charge transport medium layer in the photoreceptor shown in FIG. 3 is 10 to 95% by weight, preferably 30
~90% by weight. In addition, a plasticizer can be used together with a binder in producing any of the photoreceptors shown in FIGS. 1 to 3. In the photoreceptor of the present invention, the conductive support may be a metal plate or metal foil such as aluminum, a plastic film on which metal such as aluminum is vapor-deposited,
Alternatively, paper or the like that has been subjected to conductive treatment may be used. As a binder, condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, polyvinyl ketone,
polystyrene, poly-N-vinylcarbazole,
Examples include vinyl polymers such as polyacrylamide, but any insulating and adhesive resin can be used. Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. In addition, examples of charge transferable substances include polymers such as poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene,
Vinyl polymers such as polyvinyl indoquinoxaline, polyvinyldibenzothiophene, polyvinylanthracene, and polyvinylacridine, and condensation resins such as pyrene-formaldehyde resin, propylene-formaldehyde resin, ethylcarbazole-formaldehyde resin, chloroethylcarbazole-formaldehyde resin, etc. Low molecular weight (monomer) fluorenone, 2-nitro-9-fluorenone, 2,7-dinitro-9-fluorenone, 2,4,7-trinitro-9-fluorenone, 2,4,5,7- Tetranitro-9-
Fluorenone, 4H-indeno[1,2-b]thiophen-4-one, 2-nitro-4H-indeno[1,2-b]thiophen-4-one, 2,
6,8-trinitro-4H-indeno[1,2-
b] Thiophen-4-one, 8H-indeno[2,1-b]thiophene-8-one, 2-nitro-8H-indeno[2,1-b]thiophene-
8-one, 2-prom-6,8-dinitro-4H
-indeno[1,2-b]thiophene, 6,8-
Dinitro-4H-indeno[1,2-b]thiophene, 2-nitrodibenzothiophene, 2,8-
dinitrodibenzothiophene, 3-nitro-dibenzothiophene-5-oxide, 3,7-dinitro-dibenzothiophene-5-oxide,
1,3,7-trinitro-dibenzothiophene-
5,5-dioxide, 3-nitro-dibenzothiophene-5,5-dioxide, 3,7-dinitro-dibenzothiophene-5,5-dioxide, 4-dicyanomethylene-4H-indeno[1, 2,b]thiophene, 6,8-dinitro-
4-dicyanomethylene-4H-indeno[1,2
-b]thiophene, 1,3,7,9-tetranitrobenzo[c]cinnoline-5-oxide,
2,4,10-trinitrobenzo[c]cinnoline-6-oxide, 2,4,8-trinitrobenzo[c]cinnoline-6-oxide, 2,4,
8-trinitrothioxanthone, 2,4,7-trinitro-9,10-phenanthrenequinone, 1,
4-Naphthoquinonebenzo[a]anthracene-
7,12-dione, 2,4,7-trinitro-9-
Dicyanomethylenefluorene, tetrachlorophthalic anhydride, 1-prompyrene, 1-methylpyrene, 1-ethylpyrene, 1-acetylpyrene, carbazole, N-ethylcarbazole, N-β-
Chloroethylcarbazole, N-β-hydroxyethylcarbazole, 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-diethylaminophenyl)pyrazoline, 2
-Phenyl-4-(4-diethylaminophenyl)-5-phenyloxazole, triphenylamine, tris(4-diethylaminophenyl)
Methane, 3,6-bis(dibenzylamino)-9
-Ethylcarbazole and the like. These charge transfer substances may be used alone or in combination 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 obtain a copy using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed, and then developed.
If necessary, it can be transferred to plain paper or the like and fixed. The photoreceptor of the present invention generally has excellent advantages such as high sensitivity and flexibility. Examples are shown below. Example 1 1 part by weight of polyester resin (Polyester Adhesive 49000 manufactured by Dupont), 1 part by weight of No. 1 monoazo pigment, and 26 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was
It was coated on a polyester film on which aluminum was vapor-deposited using a doctor blade and dried at 100° C. for 10 minutes to obtain a photoreceptor having a photosensitive layer having a thickness of 7 μm as shown in FIG. 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 positively charge it, and then it was left in a dark place for 20 seconds, and the surface potential at that time was Vpo (volts). Then, the photosensitive layer is irradiated with light from a tungsten lamp so that the surface illuminance becomes 20 lux, and the time (seconds) until the surface potential becomes 1/2 of Vpo is determined, and the half-reduced exposure amount E1 is determined. /2 (lux seconds). The results were Vpo=590V and E1/2=6.5 Lux·sec. Examples 2 to 10 Photoreceptors were prepared according to the photoreceptor preparation method of Example 1, except that monoazo pigments having the numbers shown in Table 1 below were used in place of the No. 1 monoazo pigment in Example 1. The same measurements as in Example 1 were carried out on these photoreceptors, and the results shown in Table 1 were obtained.

[Table] Example 11 10 parts by weight of the same polyester resin as Example 1,
10 parts by weight of 2,4,7-trinitro-9-fluorenone, 2 parts by weight of No. 1 monoazo pigment, and 198 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied to a polyester film coated with aluminum. The photoreceptor was coated on top using a doctor blade and dried at 100° C. for 10 minutes to produce a photoreceptor having a photosensitive layer with a thickness of 10 μm as shown in FIG. 2. Next, the Vpo and E1/2 of this photoreceptor were measured using the same method as in Example 1 except that corona discharge was performed at -6KV, and the results were Vpo = 850V, E1/2 = 8.0 Lux・sec. Obtained. Examples 12 to 20 In Example 11, the monoazo pigments shown in the numbers shown in Table 2 below were used in place of the No. 1 monoazo pigment to prepare photoreceptors in the form shown in FIG.
Vpo and E1/2 were determined using the same method as above, and the results shown in Table 2 were obtained.

[Table] Example 21 10 parts by weight of the same polyester resin as Example 1,
2.5-bis(4-diethylaminophenyl)-1,
10 parts by weight of 3,4-oxadiazole, 2 parts by weight of No. 1 monoazo pigment, and 198 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. 120
By drying at ℃ for 10 minutes, a photoreceptor having a photosensitive layer having a thickness of 10 μm as shown in FIG. 2 was prepared. Hereinafter, the same measurements as in Example 1 were performed on this photoreceptor, and Vpo=
The result was 950 volts and E1/2 = 9.0 lux seconds. Examples 22 to 30 A photoreceptor having the form shown in FIG. 2 was prepared in the same manner as in Example 21 except that the monoazo pigments shown in Table 3 below were used in place of the monoazo pigment No. 1 in Example 21, The same measurements as in Example 1 were then carried out, and the results shown in Table 3 were obtained.

【table】

[Table] Example 31 200 parts by weight of poly-N-vinylcarbazole,
33 parts by weight of 2,4,7-trinitro-9-fluorenone, 20 parts by weight of polyester resin (same as in Example 1), and 20 parts by weight of No. 1 monoazo pigment were added to 1780 parts by weight of tetrahydrofuran, and the mixture was ground and mixed in a ball mill. The resulting dispersion was applied with a doctor blade onto a polyester film on which aluminum had been vapor-deposited, and dried at 100°C for 10 minutes and then at 120°C for 5 minutes to form a photosensitive layer with a thickness of 13μ as shown in Figure 2. A photoreceptor with the same shape was created. When the same measurements as in Example 1 were carried out on this photoreceptor, the results were that Vpo=1360 volts and E1/2=2.5 lux·sec. Examples 32 to 40 In Example 31, the monoazo pigments shown in Table 4 below were used in place of the monoazo pigment No. 1 to prepare photoreceptors in the form shown in Figure 2, and the same method as in Example 1 was used.
Vpo and E1/2 were determined and the results shown in Table 4 were obtained.

【table】

[Table] Example 41 2 parts by weight of No. 1 monoazo 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 carrier generation layer having a thickness of 1 μm was provided. on the other hand,
2 parts by weight of 2,4,7-trinitro-9-fluorenone, 2 parts by weight of polycarbonate [Panlite L manufactured by Teijin Co., Ltd.], and 46 parts by weight of tetrahydrofuran were mixed to form a dispersion, and this was poured onto the charge carrier generation layer. The photoreceptor was coated with a doctor blade and dried at 100° C. for 10 minutes to form a charge transfer medium layer with a thickness of 10 μm, thereby producing a photoreceptor having the form shown in FIG. The photoreceptor thus obtained was measured in the same manner as in Example 1, with Vpo of 950 volts and E1/2 of 5.0 lux.
Got the result in seconds. Examples 42 to 50 A photoreceptor having the form shown in FIG. 3 was prepared in the same manner as in Example 41 except that the monoazo pigments shown in Table 5 below were used in place of the monoazo pigment No. 1. The Vpo and E1/2 of these photoreceptors are shown in Table-5.

【table】

[Table] Example 51 2 parts by weight of No. 1 monoazo pigment and 98 parts by weight of tetrahydrofuran were pulverized and mixed in a Pall mill, and the resulting dispersion was applied onto an aluminum-deposited polyester film with a doctor blade and air-dried. A charge carrier generation layer having a thickness of 1 μm was formed. On the other hand, 2.5-bis(4-diethylaminophenyl)-
2 parts by weight of 1,3,4-oxadiazole, 2 parts by weight of polycarbonate (same as in Example 41) and 46 parts by weight of tetrahydrofuran were mixed to prepare a dispersion,
This was applied onto the charge carrier generation layer using a doctor blade and dried at 120° C. for 10 minutes to form a charge transfer medium layer with a thickness of 10 μm, thereby obtaining the laminated photoreceptor shown in FIG. 3. Measurements were carried out in the same manner as in Example 1 except that -6KV corona discharge was performed on the photoreceptor obtained as above, Vpo = 910 volts, E1/2 =
I got a result of 3.0 lux·sec. Examples 52 to 60 Photoreceptors of the same type as in Example 51 were prepared using the monoazo pigments shown in Table 6 below in place of the No. 1 monoazo pigment. Vpo of these photoreceptors
and E1/2 are as shown in Table-6.

【table】 [Brief explanation of the drawing]

1 to 3 are enlarged sectional views of the photoreceptor of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... Conductive support, 2, 2', 2''... Photosensitive layer, 3... Binder, 4... Monoazo pigment, 5...
Charge transport medium, 6... Charge carrier generation layer, 7... Charge transport medium layer.

Claims (1)

[Claims] 1. On a conductive support, the general formula [However, A is [Formula] [Formula] or [Formula] (where X is an aromatic ring, a heterocycle, or a substituent thereof, Ar ₁ is an aromatic ring, a heterocycle, or a substituent thereof, Ar ₂ and Ar ₃ are an aromatic ring or a substituted product thereof; R ₁ and R ₃ represent hydrogen, a lower alkyl group, a phenyl group, or a substituted product thereof; R ₂ represents a lower alkyl group, a carboxyl group, or an ester thereof; ] An electrophotographic photoreceptor characterized by having a photosensitive layer containing a monoazo pigment represented by the following.