JPS6219743B2 - - 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 disazo pigment as an active ingredient. Conventionally, as an electrophotographic photoreceptor in which a photosensitive layer containing an azo pigment as an active ingredient is provided on a conductive support, for example, a photoreceptor using a monoazo pigment (Tokuko Showa)
44-16474) and one using a benzine-based disazo pigment (Japanese Patent Application Laid-open No. 47-37543) are known. As mentioned above, these azo pigments are certainly useful materials as active ingredients in the photosensitive layer, but considering the various requirements for photoreceptors from the viewpoint of electrophotographic processes, it is difficult to fully satisfy these requirements. The reality is that we are not getting anything. Therefore, it is even more important to have a wide variety of pigments, not just azo pigments, that can serve as active ingredients, and only then can a photoreceptor suitable for a certain process be provided. 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 disazo 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 disazo pigments that can serve as active ingredients. A third object of the present invention is to provide a new highly sensitive and highly flexible electrophotographic photoreceptor containing the above-mentioned disazo pigment. The present inventors produced a group of disazo pigments and studied their application to photoreceptors. As a result, the disazo pigments having a distyrylbenzene skeleton represented by the following general formula can serve as an excellent active ingredient for photoreceptors. Based on this knowledge, the present invention was completed. That is, the present invention provides the following general formula on a conductive support: (However, in the formula, Ar represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, anthryl group, pyrenyl group, pyridyl group, thienyl group, furyl group, or carbazolyl group). An object of the present invention is to provide an electrophotographic photoreceptor characterized by having a photosensitive layer containing: Specific examples of the compounds of the above general formula used in the present invention are shown below in terms of structural formulas.

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[Table] These disazo pigments are 1,4-distyrylbenzene-4',
Easily produced by coupling 4″-bisdiazonium bistetrafluoroborate and a coupler corresponding to each pigment in an appropriate organic solvent, such as N,N-dimethylformamide (DMF), in the presence of an alkali. The coupler used here is prepared by heating 2-hydroxy-3-naphthoic acid hydrazide and aldehyde in an organic solvent such as alcohol according to the method of Franzen et al. (J. Prak. Chem. [2] 78 , 164). A specific example of its production is shown below. Production example 1,4-distyrylbenzene-4',4''-bisdiazonium bistetrafluoroborate 2.55g2
2.90 g of -cidroxy-3-naphthoic acid benzalhydrazide was dissolved in 300 ml of DMF, and a solution consisting of 1.64 g of sodium acetate and 14 ml of water was added dropwise thereto at room temperature. After completing the dropwise addition, stir at the same temperature for 2 hours.
The precipitated crystals were collected. After adding 300 ml of DMF to the residue and stirring at 80°C for 2 hours, crystals were collected again and this operation was repeated two more times. After washing with water and drying, 3.77 g of disazo pigment Compound No. 1 was obtained as blue-black crystals. Elemental analysis value Calculated value Actual value C% 76.13 75.95 H% 4.63 4.53 N% 12.25 12.19 The infrared absorption spectrum (KBrdisk) is shown in Figure 5. V _cp (secondary amide) 1670 cm ^-1 The photoreceptor of the present invention contains the above-mentioned disazo pigments, and can take the forms shown in Figures 1 to 4 depending on how these pigments are applied. The photoreceptor in FIG. 1 has a disazo pigment 4 on a conductive support 1.
(Here, it is used as a photoconductive substance.) A photosensitive layer 2 containing three resin binders is provided. Second
The photoreceptor in the figure has a disazo 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 FIGS. 3 and 4 is a modification of the photoreceptor shown in FIG. It is thought that each component in these photoreceptors has an effect on the photoreceptor due to the following phenomenon. In the photoreceptor shown in Figure 1, the disazo pigment acts as a photoconductive substance. , the generation and transfer of the charge carriers necessary for photoattenuation takes place via the pigment particles. In the case of the photoreceptor of FIG. The disazo pigment, on the other hand, acts as a charge carrier generator.This charge transfer medium does not have the ability to generate charge carriers like the disazo pigment, but it has the ability to accept and transfer the charge carriers generated from the disazo pigment. That is, in the photoreceptor shown in Fig. 2, the generation of charge carriers necessary for light attenuation is carried out by the disazo pigment, while the movement of charge carriers is mainly carried out by the charge transfer medium. Another basic condition required for the medium is that the absorption wavelength region of the charge transfer medium does not overlap with the absorption wavelength region of the disazo pigment, which is mainly in the visible region.This is necessary in order to efficiently generate charge carriers in the disazo pigment. This is because it is necessary to transmit light to the pigment surface.However, this is not the case, for example, in the case of a photoreceptor that is sensitive only to a certain wavelength.Therefore, the absorption wavelength of both the charge transfer medium and the disazo pigment is completely Next, in the photoreceptor shown in Figure 3, the light that has passed through the charge transport medium layer reaches the photosensitive layer 2'', which is the charge carrier generation layer, and the disazo pigment in that area generates charge carriers. On the other hand, the charge transfer medium layer receives injection of charge carriers and transfers them. The generation of charge carriers necessary for light attenuation is performed by the disazo pigment, and the transfer of charge carriers is carried out by the charge transfer medium. The mechanism is similar to that of the photoreceptor shown in FIG. Here again, the disazo pigment is a charge carrier generating substance. The mechanism of action of the charge transfer layer and the charge carrier generation layer in the photoreceptor shown in FIG. 4 is also the same as that in the photoreceptor shown in FIG. 3. In order to produce the photoreceptor shown in FIG. 1, a dispersion of disazo pigment particles dispersed in a binder solution may be coated on a conductive support and dried. To create the photoreceptor shown in Figure 2, fine particles of disazo pigment are dispersed in a solution containing a charge transporting substance and a binder, and the particles are coated on a conductive support and dried. good. The photoreceptor shown in Fig. 3 is made by vacuum-depositing a disazo pigment on a conductive support, or
Alternatively, fine particles of a disazo pigment may be dissolved in a suitable solvent in which a binder is dissolved, if necessary, and this may be coated and dried on a conductive support, and if necessary, the surface may be finished by a method such as buffing. After adjusting the film thickness, a solution containing a charge transporting substance and a binder is applied thereon and dried. In the case of the photoreceptor shown in FIG. 4, the order of film formation may be reversed in the method for producing the photoreceptor shown in FIG. In any case, the disazo 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 is carried out by conventional means, such as a doctor blade or wire bar. The thickness of the photosensitive layer is approximately 3 to 50 mm for those in Figures 1 and 2.
μ, preferably 5 to 20 μ. In addition, in the case of FIGS. 3 and 4, the thickness of the charge carrier generation layer is 5μ or less,
The thickness of the charge transport medium layer is preferably about 3 to 50 microns, preferably 5 to 20 microns. Further, in the photoreceptor shown in FIG. 1, the appropriate proportion of the disazo pigment in the photosensitive layer is 30 to 70% by weight, preferably about 50% by weight, based on the photosensitive layer. (As mentioned above, in the case of the photoreceptor shown in Figure 1, the disazo pigment acts as a photoconductive substance, and the generation and movement of charge carriers necessary for light attenuation occur through the pigment particles. It is desirable that the contact be continuous from the surface of the photosensitive layer to the support.For this reason, it is desirable that the proportion of the pigment in the photosensitive layer be relatively large, but considering the strength and sensitivity of the photosensitive layer, approximately 50% by weight should be good). In the photoreceptor shown in Figure 2, the proportion of the disazo pigment in the photosensitive layer is 50% by weight or less, preferably 20% by weight or less.
% by weight or less, and the proportion of charge-mobile substances is
10-95% by weight, preferably 30-90% by weight.
The proportion of the charge transporting substance in the charge transport medium layer of the photoreceptor shown in FIGS. 3 and 4 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 4. 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. Examples of binders include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide. In addition, any adhesive resin can be used. As a plasticizer, halogenated paraffin,
Examples include polychlorinated biphenyl, dimethylnaphthalene, and diptylphthalate. In addition, examples of charge-transferring substances include polymers such as poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylindoquinoxaline, polyvinyldibenzothiophene, polyvinylanthracene, and polyvinylacridine. Coalescence and condensation resins such as pyrene-formaldehyde resin, propylene-formaldehyde resin, ethylcarbazole-formaldehyde resin, chloroethyl albazole-formaldehyde resin, and 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]thiophene-4-one, 2-nitro-4H-indeno[1,2-b]thiophene-4-one, 2,6,
8-trinitro-4H-indeno [1,2-b]
Thiophene-4-one, 8H-indeno [2,1
-b] Thiophene-8-one, 2-nitro-8H
-Indeno[2,1-b]thiophene-8-one, 2-bromo-6,8-dinitro-4H-indeno[1,2-b]thiophene, 6,8-dinitro-4H-indeno[1,2 -b] Thiofene,
2-nitrodibenzothiophene, 2,8-dinitrobenzothiophene, 3-nitrodibenzothiophene-5-oxide, 3,7-dinitrodibenzothiophene-5-oxide, 1,3,7-trinitro-dibenzothio Phen-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-bromopyrene, 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-
(diethylaminophenyl)-5-phenyloxazole, triphenylamine, tris(4-diethylaminophenyl)methane, 3,6-bis(dibenzylamino)-9-ethylcarbazole-9-ethylcarbazole-3-aldehyde -1
-Methyl-tophenylhydrazone 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, aluminum oxide, etc.
Further, the film thickness is preferably 1 μm or less. 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 achieved by transferring the image to paper, etc., if necessary. 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 (manufactured by DuPont, Polyester Adhesive 49000), 1 part by weight of No. 1 disazo pigment, and 26 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was mixed with aluminum. Apply it on the vapor-deposited polyester film using a doctor blade and heat it for 10 minutes at 100℃.
After drying for a minute, a photoreceptor having a photoreceptor layer having a thickness of 7 .mu.m as shown in FIG. 1 was obtained. Next, a +6KV corona discharge was applied to the photosensitive layer surface of the 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 V _pp (volts). Then, the photosensitive layer is irradiated with light from a tungsten lamp so that the surface has an illuminance of 20 lux, and the time (seconds) until the surface potential becomes _1/2 of V _pp is calculated as the exposure amount E. It was set to _1/2 (lux seconds). The result is V _pp
= 730V, E _1/2 = 5 lux seconds. Examples 2 to 10 Photoreceptors were prepared according to the same photoreceptor preparation method as in Example 1, except that disazo pigments with the numbers shown in Table 1 below were used instead of disazo pigment No. 1 in Example 1. However, 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 polyester resin (same as Example 1), 2,4,7-trinitro-9-fluorenone
10 parts by weight, 2 parts by weight of No. 1 disazo pigment, and 198 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto a polyester film coated with aluminum using a doctor blade. Dry for 10 minutes at ℃ to thick
A photoreceptor having a photosensitive layer having a thickness of 10μ and having the configuration shown in FIG. 2 was prepared. Next, V _pp and E _1/2 of this photoreceptor were changed to - instead of +6 KV corona discharge in the previous example.
Measurements were made in exactly the same manner except that a 6 KV corona discharge was performed, and results were obtained of V _pp =390 volts and E _1/2 =8 lux·sec. Examples 12 to 20 In Example 11, the disazo pigments shown in the numbers shown in Table 2 below were used in place of the No. 1 disazo pigment to prepare a photoreceptor in the form shown in Figure 2.
V _pp and E _1/2 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 polyester resin (same as Example 1), 10 parts by weight of 2,5-bis(4-diethylaminophenyl) 1,3,4-oxadiazole, No.
2 parts by weight of the disazo pigment of No. 1 and 198 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto a polyester film coated with aluminum using a doctor blade, and dried at 120°C 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 the V
We obtained results of _pp = 900 volts and E _1/2 = 8 lux·sec. 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 disazo pigments shown in Table 3 below were used in place of the No. 1 disazo pigment in Example 21. The same measurements as in Example 1 were carried out, and the results shown in Table 3 were obtained.

[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 disazo 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. When a photoreceptor of the same type was prepared and the same measurements as in Example 1 were carried out, the results were that V _pp =1200 volts and E _1/2 =3 lux·sec. Examples 32 to 40 In Example 31, a photoreceptor having the form shown in FIG.
_{The pp} and E _1/2 were calculated and the results shown in Table 4 were obtained.

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[Table] Example 41 2 parts by weight of No. 1 disazo 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 formed. 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 prepare a dispersion liquid, and this was used as the charge carrier. Apply it on the generation layer with a doctor blade,
A charge transfer medium layer having a thickness of 10 μm was formed by drying at 100° C. for 10 minutes, and a photoreceptor having the form shown in FIG. 3 was obtained.
Example 1 Regarding the photoreceptor obtained as described above
Measured at the same time, V _pp is 680 volts, E _1/2 is 10
I got the result of lux sec. Examples 42 to 50 Photoreceptors having the form shown in FIG. 3 were prepared in the same manner as in Example 41 except that the disazo pigments shown in Table 5 below were used in place of the disazo pigment No. 1. Table 5 shows the V _pp and E _1/2 of these photoreceptors.

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[Table] Example 51 2 parts by weight of No. 1 disazo 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 to form a thick film. A charge carrier generation layer having a thickness of 1 μm was formed. on the other hand,
2 parts by weight of 9-(4-diethylaminostyryl)anthracene, 2 parts by weight of polycarbonate (same as in Example 41) and 46 parts by weight of tetrahydrofuran were mixed and dissolved, and this was applied onto the charge carrier generation layer with a doctor blade. The layer was dried at 120° C. for 10 minutes to form a charge transport medium layer with a thickness of 10 μm, thereby obtaining the laminated photoreceptor shown in FIG. Measurements were carried out in the same manner as in Example 1 except that -6 KV corona discharge was performed on the photoreceptor obtained as described above, and the results were as follows: V _pp was 1100 volts and E _1/2 6 lux sec. Obtained. Examples 52 to 60 Photoreceptors similar to Example 51 were prepared using the diazo pigments shown in Table 6 below in place of the No. 1 disazo pigment. The V _pp and E _1/2 of these photoreceptors are shown in Table 6.

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1 to 4 are enlarged sectional views of one example of the photoreceptor of the present invention, and FIG. 5 is an infrared absorption spectrum of No. 1. 1... Conductive support, 2, 2', 2'', 2...
Photosensitive layer, 3... Binder, 4... Disazo pigment, 5
...Charge transport medium, 6...Charge carrier generation layer, 7...
...Charge transport medium layer.

Claims (1)

[Claims] 1. On a conductive support, the following general formula (However, in the formula, Ar represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, an anthryl group, a pyrenyl group, a pyridyl group, a thienyl group, a furyl group, and a carbazolyl group.) 1. A photoreceptor for electrophotography, characterized by having a photosensitive layer containing as a component.