JPH05150524A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body having the high sensitivity and the durability to prevent the change of characteristics in the case of repeating utilization by providing a photosensitive layer contg. a specific azo pigment on a conductive base. CONSTITUTION:The photosensitive body is provided with the photosensitive layer contg. the azo pigment expressed by formula I on the conductive base. In the formula I, A denotes formula II or formula III. X denotes an arom. ring, heterocycle or the substitution, product thereof; for example, a benzene ring, naphthalene ring, carbazole ring or the substitution product thereof are exemplified. Ar denotes an arom. ring or the substitution product thereof; for example, a benzene ring, naphthalene ring, or the halogen substitution product etc., thereof are exemplified. R1 denotes hydrogen, lower alkyl group; R2 denotes a lower alkyl group, benzyl group, phenyl group or the substitution product thereof; for example, halogen, alkyl group, alkoxy group or nitro group, etc., are exemplified as the substitution group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing an azo pigment.

More specifically, it relates to a highly durable electrophotographic photosensitive member which has high sensitivity and is suitable for repeated use.

[0003]

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor, one having a photosensitive layer containing an inorganic photoconductor such as selenium, zinc oxide or cadmium sulfide as a main component has been widely known.

In recent years, some organic photoconductive materials have been put to practical use by taking advantage of the advantages such as easy film formation and production of a photoreceptor.

In particular, in the case of an organic photoreceptor, a laminated photoreceptor in which a charge generation layer containing a pigment or a dye which generates a charge carrier upon exposure and a charge transport layer for moving the charge in the electric field direction are functionally separated. Is commonly used. For example, as an electrophotographic photoreceptor containing a monoazo pigment or a bisazo pigment in a photosensitive layer, JP-B-44-16474 and JP-B-48 can be used.
-30513 and JP-A-52-4241 are known.

However, these azo pigments are not always satisfactory in characteristics such as sensitivity, residual potential or stability upon repeated use, and none of them can sufficiently satisfy a wide range of electrophotographic process requirements. The reality is that it has not been obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member containing a novel azo pigment which is stable to heat and light and has an excellent carrier generating ability.

Another object of the present invention is to provide an electrophotographic photosensitive member which has high sensitivity and a small residual potential and whose durability does not change even after repeated use, and which is excellent in durability.

Still another object of the present invention is to provide an electrophotographic photoreceptor containing a novel azo pigment which can effectively act as a carrier generating substance even in combination with many other carrier transferring substances. is there.

[0010]

The inventors of the present invention produced a series of azo pigments in order to achieve the above object, and studied the application thereof to electrophotographic photoreceptors. The present invention has been completed by finding that the azo pigment represented by the formula (4) can act as an active ingredient of the photoreceptor.

[0011]

[Chemical 4]

(In the formula, A represents (Chemical formula 5) or (Chemical formula 6), where X is a fragrance.

[0013]

[Chemical 5]

[0014]

[Chemical 6]

A ring, a heterocycle or a substitution product thereof, Ar an aromatic ring or a substitution product thereof, R ₁ is hydrogen, a lower alkyl group,
R ₂ represents a lower alkyl group, a benzyl group, a phenyl group or a substitution product thereof. ) In the above general formula, a specific example of X is a benzene ring,
Examples thereof include a naphthalene ring, a carbazole ring, and a substitution product thereof. Specific examples of Ar include a benzene ring, a naphthalene ring, or a halogen-substituted product, an alkyl-substituted product, an alkoxy-substituted product, or a nitro-substituted product thereof. As the lower alkyl group for R ₁ and R ₂ , those having C _{1 to} C ₄ are suitable. Further, examples of the substituent of the phenyl group in R ₂ include halogen, an alkyl group, an alkoxy group, a nitro group and the like.

[0016]

That is, in the present invention, the azo pigment represented by the general formula (Formula 4) is used as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, and Utilizing only excellent carrier generating ability,
By using this as a carrier-generating substance of a so-called function-separated type electrophotographic photosensitive member, in which generation and transfer of carriers are carried out by separate substances, it is possible to obtain excellent film properties, charge retention, sensitivity, and electrophotography such as residual potential. It is possible to prepare an electrophotographic photosensitive member which is excellent in characteristics, has little fatigue deterioration even after repeated use, and does not change the above-mentioned characteristics with respect to heat or light and can exhibit stable characteristics. ..

[0017]

EXAMPLES Specific examples of the azo pigment represented by the above general formula and useful in the present invention include, for example, structures represented by the following (formula 7) (formula 8) (formula 9) (formula 10) (formula 11) However, the azo pigments of the present invention are not limited thereto.

[0018]

[Chemical 7]

[0019]

[Chemical 8]

[0020]

[Chemical 9]

[0021]

[Chemical 10]

[0022]

[Chemical 11]

The azo pigment represented by the general formula (Formula 4) is
9-p-aminophenyl-3- (β-cyano-p′-aminostyryl) carbazole represented by the structural formula is

[0024]

[Chemical 12]

After tetrazotization by a conventional method, the tetrazonium salt is once isolated in the form of a borofluoride salt or a zinc chloride double salt, and then in the presence of an alkali in a suitable solvent such as N, N-dimethylformamide. It can be easily synthesized by performing a coupling reaction with a coupler below.

Next, a method for synthesizing a typical example of the azo pigment used in the present invention will be described. (Synthesis Example) (Exemplified Compound (Chemical Formula 7) No 10) 28.8 g of 9-p-aminophenyl-3- (β-cyano-p′-aminostyryl) carbazole was added to 6N-hydrochloric acid 120
Disperse it in ml and add 8.3 g of sodium nitrite to 25 m of water.
The solution dissolved in 1 was added dropwise with stirring under ice cooling, and then the reaction was stirred for about 1 hour under cooling. Then, while cooling the reaction solution with ice, 83 g of 42% -borohydrofluoric acid was added.

The resulting precipitate was filtered off, washed with a small amount of cold water and dried to obtain 30.3 g of tetrazonium fluoroboron salt as a brown powder.

Next, 6 g of the above-obtained tetrazonium salt was dissolved in 100 ml of dimethylformamide, and the solution was mixed with 7.9 g of 2-hydroxy-3- (m-nitrophenyl) carbamoylbenzo (a) carbazole to 600 ml of dimethylformamide. Add to the solution dissolved in at 10 to 20 ℃ with stirring. Then, a solution prepared by dissolving 2.9 g of crystalline sodium acetate in 28 ml of water is gradually added at 10 to 20 ° C with stirring. Three
After stirring at room temperature for a period of time, the formed precipitate was filtered off, thoroughly washed with 600 ml of dimethylformamide in total, washed twice with water, and finally twice with acetone twice. 11.4 g of black powder with a melting point of 250 ° C or higher after drying
Obtained.

Other azo pigments of the present invention can also be obtained according to the above-mentioned synthesis examples. The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more azo pigments represented by the general formula (Formula 4). Although various types of photosensitive layers are known, the photosensitive layer of the electrophotographic photosensitive member of the present invention can be used for any of them. Generally, it can be generally used as a photosensitive layer of the type exemplified below.

(1) A photosensitive layer in which an azo pigment is dispersed in a binder together with a charge transfer substance, if necessary (2) The layer of the above (1) is used as a charge generation layer, and the charge transfer substance is contained thereon. A photosensitive layer in which charge transfer layers are laminated or two layers are inverted.

The electrophotographic photoreceptor of the present invention can be manufactured by a conventional method. For example, an electrophotographic photoreceptor having a photosensitive layer of the type (1) is prepared by dispersing an azo pigment represented by the general formula (Chemical Formula 4) in a suitable binder coating solution dissolved in a suitable solvent. It can be produced by coating the resulting pigment dispersion on a conductive support, drying and forming a photosensitive layer having a thickness of usually several μm to several tens of μm. On the other hand, when it is used as the charge generation layer of the photosensitive layer of type (2), it is usually preferably formed to a thickness of 0.1 to 0.5 μm.

As the binder, various polymers such as polymers and copolymers of vinyl compounds such as (meth) acrylic acid ester, polyvinyl butyral and phenoxy resin are used.

The amount of the binder used is usually in the range of 0.1 to 5 times the weight of the azo pigment. In order to disperse the azo pigment in the binder in both the photosensitive layers of types (1) and (2), it is necessary to make the particles finer to have a particle size of 1 μm or less.

As the charge transfer substance used in the photosensitive layers of types (1) and (2), various known substances can be used.

For example, 4-diethylaminobenzaldehyde-N, N-diphenylhydrazone, 9-ethylcarbazole-3-aldehyde-N, N-diphenylhydrazone, 1-phenyl-3- (4'-diethylaminostyryl) -5- (4 "-Diethylaminophenyl) pyrazoline, tris (4-diethylaminophenyl) methane, tetrakis-N, N, N ', N'-o-tolyl-p-phenylenediamine, 2,5-bis (4'-diethylaminophenyl)- 1,3,4-oxadiazole, 2,4-
Examples thereof include bis (4′-diethylaminophenyl) -5-phenyloxazole.

A charge transfer layer can be prepared by dissolving one kind or a mixture of several kinds of these charge transfer substances in a suitable binder, coating and drying. Charge transfer layer is usually 10
Used as a film thickness of ˜20 μm. As the binder to be used, various polymers such as polymers and copolymers of vinyl compounds such as (meth) acrylic acid ester, polyurethane, polyester, phenoxy resin, polysulfone and polycarbonate are used. The amount used is usually 0.5 to 5 times the weight of the charge transfer substance.

In both the photosensitive layers of types (1) and (2), the conductive support on which the photosensitive layer is formed includes a metal plate made of aluminum or the like, a drum or a metal foil, and a plastic deposited with a metal such as aluminum. Film or plastic film that has been subjected to conductive treatment, plastic drum,
Examples include paper.

An adhesive layer or a barrier layer may be provided between the conductive support and the photosensitive layer in the photoreceptor obtained as described above, if necessary. Polyamide, aluminum oxide and the like are suitable as materials used for these layers.

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

Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples.

(Example 1) An aluminum sheet was used as a conductive support, on which a copolymerized nylon (trade name CM-8000 manufactured by Toray Industries, Inc.) having a thickness of 0.1 μm was used.
2 g of Exemplified Compound No. 10 and butyral resin (trade name Slexex B manufactured by Sekisui Chemical Co., Ltd.
H-3) 2 g and 100 g of tetrahydrofuran are added and dispersed in a paint conditioner for about 10 hours, and the azo pigment dispersion obtained is applied onto the intermediate layer so that the film thickness after drying is 0.1 μm. Then, it is dried to form a charge generation layer. Next, 5 g of the charge transfer substance 4-diethylaminobenzaldehyde-N, N-diphenylhydrazone was added together with 5 g of a polycarbonate resin (trade name NOVAREX 7030A manufactured by Mitsubishi Kasei Co., Ltd.), and 35 ml of dichloromethane was used.
The solution dissolved in was coated on the above-mentioned charge generation layer so that the film thickness after drying was 20 μm, and dried to form a charge transfer layer, thereby preparing the electrophotographic photoreceptor of the present invention.

The laminated electrophotographic photosensitive member thus obtained was subjected to an electrostatic copying paper test apparatus (EPA-manufactured by Kawaguchi Electric Co., Ltd.).
8100), the surface potential V ₀ (V) when charged with a corona current of −30 μA, the surface potential V ₁ (V) when left in a dark place for 1 second, and the surface when exposed to 5 lux white light. The exposure dose E _1/2 (lux · sec) required for the potential to be attenuated to _1/2 V ₁ (V) was measured.
The same measurement was repeated 1000 times. For repeated measurements, 100 lux of white light was emitted as static elimination light for 1 second.

The measurement results are shown in (Table 1).

[0044]

[Table 1]

(Examples 2 to 4) A total of three kinds of electrophotographic photoreceptors of the present invention were prepared in the same manner as in Example 1 except that the exemplified compounds 1, 5 and 13 were used as the charge generating substances. The same characteristic evaluation was performed for each of them.
The results are shown in (Table 2).

[0046]

[Table 2]

(Examples 5 to 7) The charge generating layer was formed in the same manner as in Example 1 except that the exemplified compounds 2, 10 and 12 were used as the charge generating substances. Next, as charge transfer material,
The charge generation layer is a solution of 2 g of 1-bis (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene dissolved in 20 ml of dichloromethane together with 2 g of a polycarbonate resin (trade name: Macrohole) manufactured by Bayer. An electrophotographic photosensitive member of the present invention was prepared by applying the above composition so that the film thickness after drying was 20 μm and drying it to form a charge transfer layer. The same characteristic test as in Example 1 was performed for each of these. The results are as shown in (Table 3).

[0048]

[Table 3]

[0049]

The electrophotographic photoreceptor of the present invention has been described above in detail. The electrophotographic photoreceptor of the present invention is obtained by incorporating a bisazo pigment having a cyanostyryl-substituted carbazole ring skeleton into its photosensitive layer. , With high sensitivity,
Even when it was repeatedly used, the sensitivity and chargeability did not fluctuate, and the durability was extremely excellent.

Claims (1)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive layer and a photosensitive layer containing an azo pigment represented by the general formula (Formula 1) on a conductive support. [Chemical 1] (In the formula, A represents (Chemical Formula 2) or (Chemical Formula 3), where X is an aromatic group. [Chemical 3] A ring, a heterocycle or a substitution product thereof, Ar represents an aromatic ring or a substitution product thereof, R ₁ represents hydrogen, a lower alkyl group, R ₂ represents a lower alkyl group, a benzyl group, a phenyl group or a substitution product thereof. )