JPS6029108B2 - Electrophotographic photoreceptor - 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, electrophotographic photoreceptors in which a photosensitive layer containing an azo pigment as an active ingredient is provided on a conductive support include those using monoazo pigments (Japanese Patent Publication No. 44-16474) and penzidine-based disazo pigments. (Japanese Patent Publication No. 47-37543) is known.

As mentioned above, these azo pigments are certainly useful materials as active ingredients in photosensitive layers, but considering the various requirements for photoreceptors from the viewpoint of electrophotographic processes, there are still none that fully satisfy these requirements. The reality is that this is not being achieved. Therefore, it is even more important to have a wide range of pigments to choose from, not only azo pigments, but also pigments that act as active ingredients, and only then can we provide photoreceptors suitable for certain processes. It 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 dibenzothiophene 5,5-dioxide skeleton represented by the following general formula were found to be excellent active ingredients for photoreceptors. The present invention has been completed based on the finding that the present invention can function as a compound.

That is, the present invention is applied to a conductive support having the following general formula [where A is the following compound No.]. 2 to 66≧ and (where × is an aromatic moiety such as a benzene ring or a naphthalene ring,
Heterocycles such as indole rings, carbazole rings, and benzofuran rings and their substituents; rings, aromatic rings such as naphthalene rings, and substituted products thereof, R.
and R3 is selected from the group consisting of hydrogen, a lower alkyl group or a phenyl group, and a substituted product thereof, and R2 is selected from the group consisting of a lower alkyl group, a carboxyl group, and an ester thereof.

) selected from the group consisting of: The present invention provides an electrophotographic photoreceptor characterized by having a photosensitive layer containing a disazo pigment represented by the following as an active ingredient.

Specific examples of the compounds of the above general formula used in the present invention are shown below in terms of structural formulas.

is common, so it will be omitted and written as -Y-.

These disazo pigments use 3,7-diaminodibenzothiophene-5,5-dioxide, which is easily obtained as a commercial product or by a known manufacturing method, as a starting material, which is first diazotized by a conventional method and isolated as a tetrazonium salt. After that, it can be easily produced by coupling with a naphthol AS coupler corresponding to each of the above-mentioned pigments in an appropriate organic solvent such as N.N-dimethylformamide in the presence of an alkali.

For example, the above No. The method for producing pigment No. 1 is as follows. Note that other disazo pigments can also be produced according to this production example, except that the raw materials are changed. Production example 317-diaminodibenzothiophene-5,5-dioxide 1. Add R to dilute hydrochloric acid prepared from 9 parts of concentrated hydrochloric acid and 9 parts of water, and stir well at 600°C for about 3 minutes.

The mixture was then cooled to about 0°C and the sodium nitrite was
．． A solution of &y dissolved in 1 part of water is added dropwise at 0 to 5°C over about 3 minutes. After that, the mixture was incubated at the same temperature for about 3 seconds, a small amount of unreacted material was removed by the furnace, and the furnace solution was poured into 42% hydrofluoric acid. and drying to obtain 2.20 (99%) yellow crystals of bisdiazonium bistetrafluoroborate. Decomposition point: about 14 p0 Next, 2.2x of the tetrazonium salt obtained in this way and 2.9 groups of 2-hydroxy-3 naphthoic acid anilides as a coupler were dissolved in 425 of the cooled N.N-dimethylformamide. A solution consisting of 4.1 parts of sodium acetate and 60 parts of water was added dropwise over a period of 1 hour at a temperature of 4 to 8°C, and then the mixture was stirred at room temperature for about 3 hours.

After that, the precipitate was collected in a furnace and washed three times with 300 ml of water.
Wash 8 times with 300% N.N-dimethylformamide. Furthermore, the remaining N·N-dimethylformamide was washed away with acetone, and the resulting blue-black crystals were dried at 70°C under a reduced pressure of 2 Hg. 1 disazo pigment 3.2
Obtain evening (80%). Melting point 300qo or higher. Elemental analysis results (as C4 Niji 3bu 606S) Calculated value Actual value C%
69.51 Road. 95 H% 3.80 3.79 N% 10.57 10.85 IR absorption spectrum (KBr tablet) 1 Kayu0ka-1 (secondary amide) The photoreceptor of the present invention contains the above disazo pigment. However, depending on how these pigments are applied, they can take the forms shown in Figures 1 to 4.

The photoreceptor shown in FIG. 1 has a disazo pigment 4 (
Here, a photosensitive layer 2 containing a resin binder (used as a photoconductive substance) and a resin binder is provided. The photoreceptor in FIG. 2 is a photoreceptor based on a conductive support 1, a disazo pigment 4 (here used as an exposure carrier generating material) to a charge transport medium (a mixture of a charge transport material and a resin binder), and 5 systems. A layer 2' is provided. The photoreceptor shown in FIGS. 3 and 4 is a modification of the photoreceptor shown in FIG. 2, and the photoreceptor layers 2'', 2, . It is thought that each component in these photoreceptors has the following mechanism of action.

First, in the photoreceptor shown in FIG. 1, the disazo pigment acts as a photoconductive substance, and the generation and movement of charge carriers necessary for light attenuation take place via the pigment particles. In the case of the photoreceptor shown in Figure 2, the charge-transfer substance is a binder (and optionally a plasticizer).
together form a charge transport medium, while the disazo pigment acts as a charge carrier generator. Although this charge transfer medium does not have the ability to generate tortoise carriers like disazo pigments, it has the ability to accept and transport tortoise carriers generated from disazo pigments. That is, in the photoreceptor shown in FIG. 2, the formation of carriers necessary for light attenuation is carried out by the disazo pigment, while the movement of the carriers is carried out mainly by the charge transfer medium. Here, another 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 disazo pigment, which is mainly in the visible region. This is because in order to efficiently generate charge carriers in the disazo 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 specific wavelength. Therefore, the absorption wavelengths of both the charge transfer medium and the disazo pigment need not completely overlap. Next, in the photoreceptor shown in FIG. 3, the charge transfer medium layer passes through the photosensitive layer 2'', which is the tortoise carrier generation layer, and the disazo pigment in that part generates tortoise carriers. On the other hand, the charge transfer medium layer receives and transfers exposed carriers, and the mechanism is that the charge carriers necessary for light attenuation are generated by the disazo pigment, and the charge carriers are transferred by the charge transfer medium. This is the same as in the case of the photoreceptor shown in Fig. 2. Here again, the disazo pigment is a carrier-generating substance. The mechanism of action of the charge transport medium layer and the exposed carrier-generating layer in the photoreceptor shown in Fig. 4 is as follows. This is the same as the case of the photoreceptor shown in Figure 3.To create the photoreceptor shown in Figure 1, a dispersion of fine particles of disazo pigment dispersed in a binder solution is coated on a conductive support and dried. good.

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 can be made by vacuum-depositing a disazo pigment onto a conductive support, or by dispersing fine particles of the disazo pigment in a suitable solvent in which a binder is dissolved, if necessary. It is obtained by applying a solution on the body and drying it, and if necessary, finishing the surface by buffing or adjusting the film thickness, and then applying a solution containing a charge-transfer substance and a binder thereon and drying it. . In the case of the photoreceptor shown in FIG. 4, the order of layer 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 mm or less, preferably 2 mm 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 in FIGS. 1 and 2 is about 3 to 50 mm, preferably 5 to 20 mm. Also 3rd~
In the case shown in Fig. 4, the thickness of the haze carrier generation layer is preferably 5 mm or less, preferably 2 peaks or less, and the thickness of the charge transport medium layer is about 3 mm.
~50 Buddhas, preferably 5-20 Buddhas. In the photoreceptor shown in FIG. 1, the proportion of the disazo pigment in the photosensitive layer is preferably 30 to 7% by weight, preferably about 5% 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 formation and movement of the exposed carrier necessary for light attenuation is performed via the pigment particles. It is preferable that the contact between the layers is continuous from the surface of the photosensitive layer to the support.For this reason, it is preferable that the proportion of the pigment in the photosensitive layer be relatively large, but considering the strength and sensitivity of the photosensitive layer, it is preferable that the proportion of pigment in the photosensitive layer be relatively large. % by weight). In the photoreceptor shown in FIG. 2, the proportion of the disazo pigment in the photosensitive layer is 5% by weight or less, preferably 2% by weight or less,
The proportion of the charge-transfer substance is 10 to 95% by weight, preferably 30 to 9% by weight. Further, the proportion of the charge transporting substance in the charge transport medium layer of the photoreceptor shown in FIGS.
, preferably from 30 to 9% by weight. In addition, 1st to 4th
In producing any of the photoreceptors shown in the figures, a plasticizer can be used together with a binder. In the photoreceptor of the present invention, a metal plate or metal foil such as aluminum, a plastic film deposited with metal such as aluminum, or paper treated with conductive treatment is used as the conductive support. Examples include condensation resins such as carbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide, but any insulating and adhesive resin can be used.

Examples of plasticizers include halogenated paraffins, polychlorinated biphenyls, dimethylnaphthalene, and dibutyl phthalate. In addition, examples of charge-transferring substances include polymers such as poly-N-pynylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylindoquinoxaline, polyvinyldibenzothiophene, polyvinylanthracene, and polyvinylacridine. Coalescence and condensation resins such as pyrene-formaldehyde resin, bromopyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, chloroethylcarbazole-formaldehyde resin, etc.
Monomers) include fluorenone, 2-nitro-9-fluorenone, 2,7-dinitro-9-fluorenone, 2
・4,7-trinitro9-fluorenone, 2,4,5
・7-tetranitro 9-fluorenone, 4-day-indeno[1,21b]thiophene-4-one, 2-nitro 4-day-indeno[1,21b]thiophene-4-one,
2.6.8-Trinitro 14 days-Indeno [1.21b
] Thiophene-4-one, Mother's day one indeno [2.11b
] Thiophene-8-one, 2 nitro-Mother's day 1 indeno [2.11b] Thiophene-8-one, 2-fromu 6
・8-dinitro' 1 day indeno [1, 2-b] thiophene, 61, 8-dinitro 4 days - indeno [1, 21 b] thiophene, 2 nitrodibenzothiophene, 2,
8-Dinitrodibenzothiophene, 3nitrodibenzothiophene-5-oxide, 3,7-dinitrodibenzothiophene-5-oxide, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, 3nitrodibenzothiophene-5-oxide . Dibenzothiophene-5,5-dioxide, 3.
7-dinitrodibenzothiophene 5,5-dioxide, 4-dicyanomethylene-4-day-inde/[1,2-b
] Thiophene, 6,8-dinitro 4-dicyanomethylene-4H-indeno [1,21b] 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-trinit. 19,101-phenanthrenequinone, 1,4naphthoquinone, benzo[a]anthracene-7,12-dione, 2
・4,7-trinitro-9-dicyanomethylenefluorene, tetrachlorophthalic anhydride, 1-frompyrene, 1
-Methylpyrene, 1-ethylpyrene, 1-acetylpyrene, Cal/azole, N-ethylcarbazole, N-8
- Quaroethylcarbazole, N-8-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)-5-1(4-diethylaminophenyl)pyrazoline, 2-phenyl-4-(4 -diethylaminophenyl)-151 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 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, and the like, and the film thickness is preferably 1 mm or less. Copying using the photoreceptor of the present invention is accomplished by charging and exposing the surface of the photosensitive layer, developing it, and, if necessary, transferring it to paper or the like.

The photoreceptor of the present invention generally has excellent advantages such as high sensitivity and excellent maneuverability.

Examples are shown below.

Example 1 1 part by weight of polyester resin (manufactured by DuPont, Polyester Adhesive 49000), No. 1 part by weight of the disazo pigment of No. 1 and 2 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 and dried under 100 degrees Celsius for 10 minutes. A photoreceptor having the configuration shown in FIG. 1 having a photoreceptor layer having a thickness of seven layers was obtained.

Next, the surface of the photosensitive layer of this photoreceptor was positively charged by applying a Juro V corona discharge using a commercially available electrostatic copying paper tester, and then left in a dark place on the second stage. Potential V
Measure po (volts), then irradiate the photosensitive layer with light from a tungsten lamp so that the surface has an illuminance of 20 lux, and find the time (seconds) until the surface potential becomes 1/2 of Vpo. Lightning intensity EI/2 (lux seconds)
And so.

The results were Vpo=500V and EI'2 15 lux·sec. Examples 2 to 10 In Example 1, NO. Photoreceptors were prepared according to the same photoreceptor manufacturing method as in Example 1, except that disazo pigments having the numbers shown in Table 1 below were used instead of disazo pigment No. 1. Measurements were carried out and the results shown in Table 1 were obtained.

Table 1 Example 11 Polyester resin (same as Example 1) 1 part by weight, 2.
Parts by weight of 4,7-trinitro-9-fluorenone 1, N
o. 2 parts by weight of the disazo pigment No. 1 and 19 parts by weight of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto a polyester film deposited with aluminum using a doctor blade, and then mixed with 1 at 100 qo.
After drying for 0 minutes, a photoreceptor having a photoreceptor layer having a thickness of 10 mm as shown in FIG. 2 was prepared.

Next, the Vpo and EI/2 of this photoreceptor were measured in exactly the same manner as in the previous example except that instead of the corona discharge of Juro V, the corona discharge of the shoe V was performed, and Vpo = 500 volts and EI/2. I got a result of 2 = 8 looks/sand. Example
12-20 In Example 11, No. A photoreceptor of the form shown in FIG. 2 was prepared by using each of the disazo pigments shown in Table 2 below in place of the disazo pigment No. 1, and Vpo and EI/2 were determined in the same manner as in Example 11. 2 results were obtained.

Table 2 Example 21 Polyester resin (same as Example 1) Blood weight parts, 2.5
-bis(4-jethylaminophenyl)-1,3,4-oxadiazole 10 parts by weight, No. 2 parts by weight of the disazo pigment of No. 1 and 19 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 and dried at 120°C for 10 minutes. and thickness 10
A photoreceptor having the form of FIG.

Below, the same measurements as in Example 1 were performed on this photoreceptor,
The results were Vpo = 800 volts and EI'2 = 6 lux seconds. Examples 22 to 30 In Example 21, No. 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 disazo pigments in Table 1. -3 result was obtained.

Table-3 Example 31 200 parts by weight of poly-N-pinylcarbazole, 2.4.
33 parts by weight of 7-trinitro-9-fluorene/one, 2 parts by weight of polyester resin (same as in Example 1) and No. 1
178 parts by weight of disazo pigment 2 in tetrahydrofuran
The resulting dispersion was applied with a doctor blade onto a polyester film coated with aluminum, dried at 10,000 for 1 minute, then at 12,000 for 5 minutes, and the thickness A photoreceptor having the form of FIG. 2 having 13 photosensitive layers was prepared, and Example 1 was prepared.
When the same measurements were carried out as above, the results were that Vpo=1000 volts and EI'2=3 lux·sec.

Examples 32 to 40 In Example 31, No. A photoreceptor of the form shown in FIG. 2 was prepared by using the disazo pigments shown in Table 4 below in place of the disazo pigment No. 1, and Vpo and EI/
2 was obtained, and the results shown in Table 4 were obtained.

Table-4 Example 41 No. 2 parts by weight of the disazo pigment of No. 1 and 1 part by weight of tetrahydrofuran are pulverized and mixed in a ball mill, and the resulting dispersion is applied onto an aluminum vapor-deposited polyester film using a doctor blade and air-dried to form a 1 um thick exposed film. A body developmental layer was formed.

On the other hand, 2 parts by weight of 2,4,7-trinitro-9-fluorenone, polycarbonate [■ Manufactured by Tijin, Panlite L
] 2 parts by weight and tetrahydride. 4 parts by weight of furan were mixed to form a solution, which was applied onto the charge carrier generation layer using a doctor blade and dried at 100° C. for 1 minute to a thickness of 1.
A charge transfer medium layer of 0 µm was formed, and a photoreceptor having the form shown in FIG. 3 was obtained. The photoreceptor obtained as described above was measured in the same manner as in Example 1, and the Vpo was 800 volts and the EI/
2 obtained a result of 15 lux·sec. Examples 42-5
0 In Example 42, NO. A photoreceptor having the form shown in FIG. 3 was prepared in the same manner except that disazo pigments shown in Table 5 below were used in place of disazo pigment No. 1.

Table 5 shows the Vpo and EI/2 of these photoreceptors. Table-5 Example 51 No. 2 parts by weight of the disazo pigment of No. 1 and 98 parts by weight of tetrahydrofuran are pulverized and mixed in a ball mill, and the resulting solution is applied onto an aluminum vapor-deposited polyester film with a doctor blade and air-dried to form a charge loss body generation layer with a thickness of 1 French. was formed.

Meanwhile, 2 parts by weight of 2,5-pis(4-diethylaminophenyl)-1,3,4-oxadiazole, 2 parts by weight of polycarbonate (same as in Example 41), and 4 parts by weight of tetrahydrofuran were mixed and dispersed. This was applied as a liquid onto the charge carrier generation layer using a doctor blade, and 120 qo
The layer was dried for 10 minutes to form a charge transfer medium layer having a thickness of 10 layers, thereby obtaining the laminated photoreceptor shown in FIG. The photoreceptor obtained as described above was measured in the same manner as in Example 1, except that Ichiro V corona discharge was performed, and the Vpo of this material was measured in the same manner as in Example 1.
obtained a result of 1000 volts and EI/2 of 8 lux seconds. Examples 52 to 60 In Example 51, No. 1
Photoreceptors of the same type were prepared by using the disazo pigments shown in Table 6 below in place of the disazo pigments shown in Table 6 below.

The Vpo and EI/2 of these photoreceptors are shown in Table-6. Table 6 Examples 61 to 96 75 parts by weight of the disazo pigment shown in Table 17, 25 parts by weight of polyester resin [■ Toyobo Seisei Byron 200], and 490 parts by weight of tetrahydrofuran were ground and mixed in a ball mill, and the resulting dispersion was obtained. was applied onto an aluminum vapor-deposited polyester film using a doctor blade and air-dried to form a charge generation layer about 1 French thick.

On the other hand, 2 parts by weight of the charge transfer substance shown in Table 7, 2 parts by weight of polycarbonate resin [Panlite K1300 manufactured by Tijin] and 16 parts by weight of tetrahydrofuran were mixed and dissolved.
It was applied onto the charge generation layer using a doctor blade and dried at 80°C for 2 minutes and then at 1050C for 5 minutes to form a charge transfer layer having a thickness of about 10 peaks, thereby producing a photoreceptor in the form shown in FIG. 3. The electrostatic properties of these photoreceptors were measured in the same manner as in Example 51, and the results shown in Table 8 were obtained. In addition, in Table 8,
EI/5 represents the amount of exposure required for the surface potential to become 1'5 of Vpo, and EI/10 represents the amount of exposure required for the surface potential to become 1/10 of Vpo. Table-7 80 General formula in parentheses 1 Table-8

[Brief explanation of the drawing]

1 to 4 are enlarged sectional views of one example of the photoreceptor of the present invention. 1... Conductive support, 2, 2', 2'', 2''
'...Photosensitive layer, 3...Binder, 4...
... Disazo pigment, 5 ... Charge transfer medium, 6.
. . . Charge carrier generation layer, 7 . . . Charge transport medium layer. Younger brother Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. on the conductive support ▼ [However, A is ▲ There are ▲ Numerical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, X is an aromatic ring, a heterocycle, and a substituent thereof, A
r_1 is an aromatic ring, a heterocycle and a substituted product thereof, Ar_
2 and Ar_3 are selected from the group consisting of an aromatic ring and a substituent thereof, R_1 and R_3 are hydrogen, a lower alkyl group or a phenyl group and a substituent thereof, and R_2 is a lower alkyl group, a carboxyl group and an ester thereof. ) selected from the group consisting of: 1. A photoreceptor for electrophotography, comprising a photosensitive layer containing a disazo pigment as an active ingredient.