JPH0377958A - Electrophographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance heat and light stability and carrier generating ability by forming a photosensitive layer containing a specified azo pigment. CONSTITUTION:The photosensitive layer contains the azo pigment represented by formula I in which X is an aryl or heterocylclic group each optionally substituted; Ar is optionally substituted aryl: R1 is H, lower alkyl, or the like; R2 is lower alkyl, or optionally substituted phenyl; and A is a group represented by formula II, III, or IV. This azo pigment is used as a photoconductor for the photosensitive layer, or only the superior carrier generating ability is used and other materials are used for transfer of carriers, that is, it is used as the carrier generating material of the so-called functionally separated photosensitive body, thus permitting the obtained electrophotographic sensitive body to be superior in film forming physical property, and electarophotographic characteristics, such as potential stability, sensitivity, or residual potential stabil ity, and to be small in deterioration at the time of repeated uses, not to be changed in these characteristics by heat and light, and to exhibit stable characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION 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, the present invention relates to a highly durable electrophotographic photoreceptor that has high sensitivity and is suitable for repeated use.

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

In recent years, some organic photoconductive materials have been put into practical use, taking advantage of their advantages such as ease of film formation and production of photoreceptors.

In particular, in the case of organic photoreceptors, a laminated photoreceptor is generally used, which is functionally separated into a charge generation layer containing a pigment or dye that generates charge carriers upon exposure to light, and a charge transport layer that moves the charges in the direction of the electric field. For example, electrophotographic photoreceptors containing monoazo pigments or bisazo pigments in the photosensitive layer are disclosed in Japanese Patent Publication No. 44-16474 and Japanese Patent Publication No. 4 B-
Publication No. 30513, Japanese Unexamined Patent Publication No. 52-4241, etc. are known.

However, these azo pigments are not necessarily satisfactory in terms of properties such as intensity, residual potential, and stability when used repeatedly, and so far no azo pigment has been obtained that fully satisfies the wide-ranging demands of electrophotographic processes. The reality is that it is not.

Problems to be Solved by the Invention An object of the present invention is to provide an electrophotographic photoreceptor containing a novel azo pigment that is stable to heat and light and has excellent carrier generation ability.

Another object of the present invention is to provide high sensitivity, low residual potential,
Another object of the present invention is to provide an electrophotographic photoreceptor with excellent durability whose properties do not change even after repeated use.

Still another object of the present invention is to provide an electrophotographic photoreceptor containing a novel Ab [4] that can effectively act as a carrier generating material even in combination with many other carrier moving materials.

Means for Solving the Problems In order to achieve the above object, the present inventors produced a series of bisazo pigments and studied their application to electrophotographic photoreceptors. The present invention was completed based on the discovery that the ab pigment contained in the photoreceptor can function as an active ingredient of a photoreceptor.

(In the formula, 8 represents an alkyl group,
Represents a phenyl group or a substituted product thereof. ) In addition, in the above-mentioned - binding allowance, specific examples of X include benzene ring,
Examples include naphthalene rings, carbazole rings, and substituted products thereof. Specific examples of A include a Hensen ring, a napkin ring, or a halogen-substituted product, an alkyl-substituted product, an alkoxy-substituted product, or a nitro-substituted product thereof.

The lower alkyl group in R1 and R2 is 01-
C4 is suitable.

In other words, in the present invention, by using the azo pigment represented by the general formula (I) as a photoconductive material constituting the photosensitive layer of an electrophotographic photoreceptor, the azo pigment of the present invention can achieve excellent carrier generation. By using this as a carrier generation material for so-called function-separated electrophotographic photoreceptors, in which carrier generation and transfer are performed using separate materials, film-forming properties are excellent, and charge retention and sensitivity are improved. .

It has excellent electrophotographic properties such as residual potential, and has little fatigue deterioration even after repeated use, and the above-mentioned properties do not change even when exposed to heat or light. A photoreceptor can be created.

Examples Specific examples of the azo pigments useful in the present invention shown in the above-mentioned margin include those having the following structural formula, but the azo pigments of the present invention are not limited thereto.

The azo pigment represented by the general formula (I) has the following structural formula (
If) p-bis-(2-(p-aminophenyl)-4
-Oxasilyl]Hensen is tetrazotized by a conventional method,
The corresponding coupler is then coupled in the presence of an alkali, or the tetrazonium salt of the diamine is once isolated in the form of a borofluoride salt or a zinc chloride double salt, etc., and then a suitable solvent such as N, N- It can be easily synthesized by coupling with a coupler in the presence of an alkali in a solvent such as dimethylformamide.

Next, a method for synthesizing a typical example of the ab pigment used in the present invention will be described.

Synthesis Example (Exemplary Compound 7) 5.9g of p-bis[2-(p-aminophenyl)-4=oxaduryl]benzene was dissolved in 60d of 6N-hydrochloric acid,
A solution prepared by dissolving 2.24 g of sodium nitrite in a small amount of water was added dropwise while stirring under water cooling, and the mixture was stirred and reacted under cooling for about 1 hour. This was heated to 211 degrees to obtain a filtrate containing a tetranium salt.

8.93 g of 2-hydroxy-3-(0-chlorophenyl)naphthoic acid amide as a coupling component, 3 g of triethylamine as an organic amine, and dimethylformamide]
Dissolved in OOOd for 7 hours and cooled to 0-5'C. Next, the above tetrazonium salt solution was added dropwise to the Camplar solution, and the resulting blue-purple paste liquid was kept at 0 to 10°C and stirred for an additional 3 hours. The formed precipitate is filtered,
It was thoroughly washed with 4000 ml of dimethylformamide, and finally with water, and after drying, 4.2 g of blue-purple powder was obtained. The melting point was 300°C or higher.

Other ab pigments of the present invention can also be obtained according to the above synthesis example.

The electrophotographic window light material of the present invention has a photosensitive layer containing one or more types of azo pigments represented by the above-mentioned - binding margin (+). Various types of photosensitive layers are well known, and the photosensitive layer of the electrophotographic photoreceptor of the present invention can be used in any of them. Generally, the following types of photosensitive layers can be used.

■ A photosensitive layer in which an ab pigment is dispersed in a binder together with a charge transfer material if necessary.■ The layer in (■) above is used as a charge generation layer, and a charge transfer layer containing a charge transfer material is laminated thereon, or two layers are formed. A photosensitive layer that is laminated in reverse.

The electrophotographic photoreceptor of the present invention can be manufactured according to a conventional method. For example, an electrophotographic photoreceptor having a photosensitive layer of the type (2) above can be prepared by dispersing an azo pigment represented by the general formula (I) in a suitable binder coating solution dissolved in a suitable solvent. It can be manufactured by applying a dispersion onto a conductive support and drying it to form a photosensitive layer having a thickness of usually several μm to several tens of μm. On the other hand, when it is used as a charge generation layer in a photosensitive layer of type (2), it is usually preferably formed to have 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 esters, polyurethanes, polyesters, epoxy resins, phenoxy resins, polysulfones, and polycarbonates are used.

The amount of binder used is usually 0.1 to 5% relative to the azo pigment.
The range is twice the weight.

In both types of photosensitive layers (1) and (2), in order to disperse the ab pigment in the binder, it is necessary to micronize the ab pigment to preferably a particle size of 1 μm or less.

Various known materials can be used as the charge transfer materials used in the photosensitive layers of types (1) and (2).

For example, 4-diethylaminobeni/dualdehyde'NN-
'; Phenylhydrazone 9-ethylcarbazole-3
-Aldehyde-NN-diphenylhydrazone, 1-phenyl-3-(4'-diethylaminostyryl)-5-
(4”-diethylaminophenyl)pyrazolino, tris(4-diethylaminophenyl)methane, tetrakis-
N,N,N'N'-o-tolyl-p-phenylenediamine, 2゜5-bis(4'-diethylaminophenyl)-
1゜3.4-oxadiazole, 2.4-bis(4'-
Diethylaminophenyl)-5-phenyloxazole and the like can be mentioned.

One or a mixture of these charge transport materials can be dissolved in a suitable binder, applied and dried to form a charge transport layer. The charge transport layer usually has a thickness of 10 to 20 μm.
Used as the film thickness. The binder to be used can be selected from those listed above, but the amount used is usually 0.5 to 5 times the weight of the charge transfer material.

In both types of photosensitive layers, the conductive support on which the photosensitive layer is formed is a metal plate such as aluminum, a drum or metal foil, a plastic film on which metal such as aluminum is vapor-deposited, or a conductive support. Examples include plastic films, plastic drums, and paper.

The photoreceptor obtained as described above may be provided with an adhesive layer or a barrier layer between the conductive support and the photosensitive layer, if necessary. Suitable materials for these layers include polyamide, aluminum oxide, and the like.

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

EXAMPLES Next, the present invention will be specifically explained with reference to examples, but the present invention is not limited to the following examples.

[Example I]

An aluminum sheet is used as a conductive support, and copolymerized nylon (manufactured by Toshi Co., Ltd., trade name CM-80) is applied on top of this.
00) with a thickness of 0.3 μm, and paint by adding 2 g of Exemplary Compound No. 10 and 2 g of butyral resin (manufactured by Sekisui Chemical Co., Ltd., trade name Nislex BH-3) to 100 d of tetrahydrofuran. An ab pigment dispersion obtained by dispersing in a conditioner for about 5 hours is applied onto the undercoat layer so that the film thickness after drying is 0.3 μm, and dried to form a charge generation layer.

Next, 5 g of the charge transfer material 4-diethylaminobenzaldehyde-N,N-diphenylhydrazone was added to a polycarbonate resin (manufactured by Sanka Kasei Co., Ltd., trade name: Tubarex 70).
30A) and a solution dissolved in 35d of dichloromethane were applied onto the charge generation layer described above so that the film thickness after drying was 1.
A charge transfer layer was formed by coating and drying to a thickness of 5 μm, thereby producing an electrophotographic photoreceptor of the present invention.

The surface potential V when the thus obtained laminated electrophotographic material was charged with a corona current of -30 μA using an electrostatic copying paper testing device (EPA8100 manufactured by Kawaguchi Electric Seisakusho)
o (V), surface potential V when left in a dark place for 1 second, (V), surface potential 1/2 V when exposed to 51 ux white light.

The exposure amount required to attenuate to (V) is E+zz(lu
X・5ec), were measured respectively. Further, similar measurements were repeated 1000 times. In the repeated measurements, white light of 100 ILIX was irradiated for 1 second as static elimination light.

The measurement results are shown in Table 1.

Table 1 [Examples 2 to 7] Exemplary compounds 7.11°16.
A total of six types of electrophotographic photoreceptors of the present invention were prepared in the same manner as in Example 1, except that 1B and 22.26 were used, and the characteristics of each of them were evaluated in the same manner. The results are shown in Table 2.

Table 2 [Examples 7 to 9] Exemplified compounds 2, 4, and 4 as charge generating substances, respectively. l 3゜2
A charge generation layer was formed using Example 8 in the same manner as in Example 1. Next, as a charge transfer material, 9-ethylcarbasol-
2 g of 3-aldehyde-N,N-diphenylhydrazone was mixed with 2 g of polyester resin (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.) and 20 g of 1,2-dichloroethane.
An electrophotographic photoreceptor of the present invention was prepared by coating a solution dissolved in - on the charge generation layer so as to have a dry film thickness of 15 μm and drying to form a charge transfer layer.

Characteristic tests similar to those in Example 1 were conducted for each of these. The results are shown in Table 3.

As explained in Table 3, the electrophotographic photoreceptor of the present invention has high sensitivity by containing a bisazo head having a phenylenebisoxazole skeleton in its photosensitive layer, and has excellent sensitivity and chargeability even after repeated use. It had little fluctuation and was extremely durable.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photosensitive layer containing an azo pigment represented by the following general formula (I) on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (However, in the formula, A represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, where X is (Ar represents an aromatic ring or a substituent thereof; R_1 represents hydrogen, a lower alkyl group, or a phenyl group; R_2 represents a lower alkyl group, a phenyl group, or a substituent thereof.)