JPH01246556A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body stable against heat and light and superior in carrier generating performance by incorporating a specified azo pigment. CONSTITUTION:The azo pigment to be incorporated in a photosensitive layer is represented by formula I in which R is H, alkyl, aryl, and each of X and Y is an optionally substituted aromatic carbon or hetero ring. It can be dispersed into a dispersion medium under mild conditions without impairing electrophotographic characteristics, thus permitting the obtained electrophotographic sensitive body to be superior in physical film properties, and electrophotographic characteristics, such as film properties, charge stability, sensitivity, and resistance to rise of residual potential, moreover, small in fatigue deterioration even at the time of repeated uses, unchanged in characteristics against heat and light, and capable of stably exhibiting characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Field of Application The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing an azo compound.

CB) Prior Art and its Problems Conventionally, electrophotographic photoreceptors having photosensitive layers containing inorganic photoconductors such as selenium, zinc oxide, and cadmium sulfide as main components have been widely known.

However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In addition, selenium and cadmium sulfide are particularly toxic, so there are restrictions in production and handling.

On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, and easy to handle, and are generally more expensive than selenium photoreceptors. It has many advantages such as excellent thermal stability, and has attracted a lot of attention in recent years.

As such an organic photoconductive compound, poly-N-vinylcarbazole is well known.
7-) An electrophotographic photoreceptor having a photosensitive layer containing a charge transfer complex formed from a Lewis acid such as dinitro-9-fluorenone is described in Japanese Patent Publication No. 50-10596. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability.

On the other hand, laminated type or dispersed type functionally separated plastic photoreceptors, in which the carrier generation function and the carrier transport function are assigned to separate substances, have a wide range of materials to choose from, and have improved charging characteristics, sensitivity, and durability. It has the advantage that an electrophotographic photoreceptor having arbitrary properties can be produced relatively easily.

Conventionally, various carrier-generating substances or carrier-transferring substances have been proposed.

For example, an electrophotographic photoreceptor has been put into practical use that has a photosensitive layer that combines a carrier generation a made of amorphous selenium and a carrier transfer layer made of poly-N-vinylcarbazole as a main component.

However, a carrier generation layer made of amorphous selenium has a drawback of poor durability.

Furthermore, electrophotographic photoreceptors using organic dyes or pigments as carrier-generating substances have also been proposed.

For example, JP-A-47-37543 describes a bisazo compound, JP-A-53-132347 describes a trisazo compound,
JP-A-49-11136 describes phthalocyanine compounds,
The electrophotographic photoreceptors used in each are described. However, these photoreceptors are not necessarily satisfactory in terms of characteristics such as sensitivity, residual potential, and stability when used in reverse, and the selection range of carrier transfer substances is also limited. Furthermore, many of these photoreceptors have a photosensitive wavelength range that extends to the long wavelength side of the visible range, resulting in poor image reproducibility for red originals. Therefore, when actually incorporated into a copying machine, a filter for cutting red light is required, which is inconvenient in terms of the design of the copying machine.

(C) Object of the Invention An object of the invention is to provide an electrophotographic photoreceptor containing an azo compound 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 an azo compound that can effectively act as a carrier generating substance even in combination with a wide variety of carrier transfer substances.

Yet another object of the present invention is to provide an electrophotographic photoreceptor with excellent image reproducibility for red originals.

CD) Structure of the Invention These objects of the present invention have been achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo compound represented by the following general formula (I).

[In the formula, N represents a coupler residue, R represents a hydrogen atom, an alkyl group, or an aryl group, and X and Y represent an optionally substituted carbocyclic or heterocyclic aromatic ring. ]

The azo compound represented by the general formula (I) can be dispersed in a dispersion medium under mild conditions without impairing its electrophotographic properties. Therefore, in the present invention, by using this azo compound as a photoconductive substance constituting the photosensitive layer of the electrophotographic photoreceptor, or by utilizing only its excellent carrier generation ability, so-called functional separation can be achieved in the electrophotographic photoreceptor. By using it as a carrier generating material, it has excellent film properties, excellent electrophotographic properties such as charge retention, sensitivity, and residual potential, and has little fatigue deterioration even after repeated use, and is resistant to heat and light as mentioned above. It is possible to create an electrophotographic photoreceptor that exhibits stable characteristics without changing its characteristics.

Specific examples of the azo compound represented by the above-mentioned -Momona (1) include those having the following structural formula.

Exemplary Compounds The azo compound represented by the general formula (1) of the present invention can be easily synthesized by a known method. One specific manufacturing example is shown below.

Production example (synthesis of exemplified compound 24) 2-amino-7-(p-1 minobenzoylamino)-9
- 0.33f of fluorenone in DMF solution 20-, iced water, 2N hydrochloric acid 4-1, then sodium nitrite 0.14
An aqueous solution of F 3- was added. After stirring at the same temperature for 15 minutes, water 7-
was added and further stirred for 20 minutes. The obtained diazotized liquid was added dropwise to a DMF solution of 0.531% naphthol AS and 1.82% triethanolamine over 20 minutes on ice and water.

After stirring at the same temperature for 2 hours and then at room temperature for 2 hours, the precipitated crystals were collected by filtration, washed with 100% each of DMF, water, and acetone, and dried to obtain the desired product (0.66 f).

Melting point: 30℃ or higher.

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more azo compounds represented by formula (1) above. Various forms of photosensitive layers are well known, and the photosensitive layer of the electrophotographic photoreceptor of the present invention may be in any of them. Usually, the photosensitive layer is of the type exemplified below.

■A photosensitive layer made of an azo compound ■A photosensitive layer containing an azo compound dispersed in a binder ■A photosensitive layer containing an azo compound dispersed in a well-known charge transfer substance ■The photosensitive layer of the above (■) to (■) is used as a charge generation layer. The azo compound represented by the above-mentioned formula generates charge carriers with extremely high efficiency when it absorbs light. Although the generated carriers can be transferred using an azo compound as a medium, it is preferable to transfer the generated carriers using a known charge transfer substance as a medium. From this point of view, photosensitive layers having the forms (1) and (2) are particularly preferred.

Charge transfer substances are generally classified into two types: electron transfer substances and hole transfer substances, and both can be used in the photosensitive layer of the photoreceptor of the present invention, and mixtures of substances having the same type of function, It is also possible to use mixtures of materials with different functions. Electron transfer substances include nitro group, cyano group,
It is an electron-withdrawing compound having an electron-withdrawing group such as an ester group, such as nitrated fluorenone such as 2.4.7-)linitronefluorenone and 2.4.5.7-ketonenitrofluorenone. , or compounds such as tetracyanoquinodimethane, tetracyanoethylene, 2.4°5.7-ketone nitroxanthone, 2.4.8-trinidrothioxanthone, or polymerized products of these electron-withdrawing compounds. can be given.

In addition, examples of hole transfer media include polymers having a heterocyclic compound in the side chain such as boU-hevinylcarbazole, triazole derivatives, oxadiazole derivatives, pyrazoline derivatives, triarylamine derivatives, and hydrazone derivatives. , stilbene derivatives, etc.

The charge transfer substance is not limited to those described here, and when used, one type or a mixture of two or more types of carrier transfer substances can be used.

The electrophotographic photoreceptor of the present invention can be manufactured according to a conventional method.

For example, in an electrophotographic photoreceptor having a /M optical layer of the type (2) above, a coating solution obtained by dispersing the azo compound represented by the general formula (I) in a suitable medium is coated on a conductive support. It can be manufactured by coating and drying to form a photosensitive layer having a thickness of usually several μm to several tens of μm.

As a medium for preparing the coating solution, tetrahydrofuran, 1
．． Ethers such as 4-dioxane; Ketones such as methyl ethyl ketone and cyclohexanone; Aromatic hydrocarbons such as toluene and xylene: N,N-dimethylformamide,
Aprotic polar solvents such as acetonitrile, N-methylpyrrolidone, and dimethyl sulfoxide; Alcohols such as methanol, ethanol, and impropatol; Esters such as ethyl acetate, methyl acetate, and methyl cellosolve acetate; Chlorination such as dichloroethane and chloroform Examples include a medium for dispersing an azo compound such as a hydrocarbon.

When using a medium for dispersing an azo compound, it is necessary to micronize the azo compound to a particle size of 5 μm or less, preferably 3 μm or less, and optimally 1 μm or less.

Furthermore, as the conductive support on which the photosensitive layer is formed, any of those employed in well-known electrophotographic photoreceptors can be used.

Specifically, for example, a metal drum made of aluminum, copper, etc.
Examples include sheets, laminates and vapor deposits of these metal foils.

Further examples include plastic films, plastic drums, paper, etc. which are coated with a conductive substance such as metal powder, carbon black, copper iodide, or polymer electrolyte together with a suitable binder to conductivity treatment.

Other examples include plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are made conductive.

If a binder is dissolved in the coating liquid used to form the photosensitive layer of the type (2) above, an electrophotographic photoreceptor having the photosensitive layer of the type (2) above can be produced.

In this case, the medium of the coating liquid is preferably one that dissolves the binder.

As binders, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic esters, methacrylic esters, phenoxy resins, polysulfones, arylate resins, polycarbonates, polyesters,
Examples include various polymers such as cellulose ester, cellulose ether, urethane resin, epoxy resin, and acrylic polyol resin.

The amount of binder used is usually 0.1 to 0.1 to the amount of the azo compound.
The range is 5 times the weight.

In addition, in forming this type of photosensitive layer,
Azo compound in a binder with fine particle size, e.g. 3μm
Hereinafter, it is particularly preferable to have it exist in the form of fine particles of 1 μm or less.

Similarly, by dissolving a charge transfer medium in the coating liquid used to form the photosensitive layer of the type (2) above, an electrophotographic photoreceptor having the photosensitive layer of the type (2) above can be manufactured.

As the charge transfer medium, any of those exemplified above can be used.

Apart from charge transport media which can themselves be used as binders, such as polyvinylcarbazole and polyglycidylcarbazole, it is preferred to use other binders.

As the binder, any of those exemplified above can be used.

In this case, the amount of the binder used is usually 5 to 10 times the weight of the azo compound, and the amount of the charge transport medium used is usually 0.2 to 1.5 times the weight of the binder, preferably 0.3 times. The range is 1.2 times the weight. Charge transfer gJJfJ which itself can be used as a binder! In the case of &, it is usually used in an amount of 5 to 10 times the weight of the azo compound.

In this type of photosensitive layer, it is preferable that the azo compound be present in the charge transport medium and the binder in the form of fine particles, similarly to the photosensitive layer of type (1) above.

If a charge transfer layer is formed by dissolving a charge transfer medium in a suitable medium and drying the coating solution on the photosensitive layer of the types ① to ② above, then the photosensitive layer of the type ① will be formed. An electrophotographic photoreceptor can be manufactured.

In this case, the photosensitive layers of types (1) to (4) above serve as charge generation layers. The charge transfer layer does not necessarily need to be provided above the charge generation layer, but may be provided between the charge generation layer and the conductive support. However, the former is preferable in terms of durability. The charge transfer layer is formed in the same manner as the photosensitive layer described in (2) above. That is, the coating liquid for forming the photosensitive layer described in (1) above, except that the azo compound is removed, may be used as the coating liquid. Usually the charge generation layer is 5 to 50 μm
The thickness is . Of course, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known sensitizer.

Suitable sensitizers include Lewis acids and dyes that form charge transfer complexes with organic photoconductive materials.

Examples of Lewis acids include quinones such as chloranil, 2,3-dichloro-1,4-naphthoquinone, 2-methylanthraquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-chloroanthraquinone, and phenanthrenequinone. aldehydes such as 4-nitrobenzaldehyde)'M, ketones such as 9-benzoylanthracene, indanedione, 3,5-dinitrobenzophenone, 3.3', 5゜5'-tetranitrobenzophenone, phthalic anhydride, Acid anhydrides such as 4-chlorna-7talic anhydride, cyanide compounds such as tetracyanoethylene, terephthalmalononitrile, 4-nitrobenzalmalononitrile, 3-benzal7talide, 3-(α-cyano- Examples include electron-withdrawing compounds such as phthalides such as p-nitrobenzal) phthalide.

Examples of dyes include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, quinone dyes such as quinizarin, cyanine dyes, pyrylium salts, thiapyrylium salts, and benzopyrylium salts.

In addition, organic photoconductive pigments such as inorganic photoconductive fine particles of selenium and selenium-arsenic alloys, copper phthalocyanine pigments, and perylene pigments may be contained.

Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known softening agent in order to improve film formability, flexibility, and mechanical strength. As a plasticizer, phthalate ester,
Phosphate ester, epoxy compound, chlorinated paraffin,
Examples include aromatic compounds such as chlorinated fatty acid esters and methylnaphthalene.

Moreover, it goes without saying that it may have an adhesive layer, an intermediate layer, and a transparent insulating layer, if necessary.

(E) Examples Next, the present invention will be explained in more detail by examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Examples 1 to 8 0.2 f of the exemplified compounds shown in Table 1 and 0.2 f of polyarylate (Unitika 1U-100) were added to 1,2-dichloroethane 20- and dispersed with a paint conticiller for 2 hours. Ta.

The resulting dispersion was applied onto the aluminum surface of a polyester base on which aluminum was vapor-deposited so that the film thickness after drying was about 1 μm to form a charge generation layer. Furthermore, p-
Dibenzylaminobenzaldehyde diphenylhydrazone 12f and polyaryl L'-t (22?77 units U-100
) l 2 f dissolved in aa benzene 1202 was coated and dried to a film thickness of 20 μm to form a carrier transfer@k, thereby producing an electrophotographic photoreceptor of the present invention. After storing the photoreceptor at room temperature at 30°C in a dark place, day and night, it was mounted on an electrostatic paper tester "5F-428J (Kawaguchi Electric Seisakusho M), and the following characteristic tests were conducted.

That is, a voltage of -5.5 KV was applied to the charger to charge the photosensitive layer by corona discharge for 5 seconds, and then the photosensitive layer was left in the dark for 10 seconds, and the potential Vo (-V) at that time was determined.

Next, light from a halogen lamp is irradiated with the illumination intensity on the surface of the photosensitive layer being 51 ux, and the exposure amount E7 (lux seconds) required to attenuate the surface of the photosensitive layer at position 4 to 2
I asked for Similar measurements were repeated 100 times and the results are summarized in Table 1.

Table 1 *: Lux seconds Comparative Example 1 A similar photoreceptor was prepared except that the exemplary compound used in Examples 1 to 8 was changed to a bisazo compound having the structure below.

Its electrophotographic characteristics are Vo and E'/2 of the first time - 76
0V and 5.8lux seconds, 100th time is -730V and 5.
It was 7lux seconds.

Example 9. Comparative Example 2 The spectral sensitivities of the photoreceptors prepared in Example 7 and Comparative Example 1 were determined. The results are shown in Figure 1.

(F) Effects of the Invention The photoreceptor using the azo compound of the present invention has high sensitivity, and when used repeatedly, there is little variation in sensitivity and chargeability, little optical fatigue, and extremely excellent durability. Also,
Since the sensitive wavelength range is approximately 500 to 620 nm, it can be seen that the reproducibility of red originals is good.

[Brief explanation of the drawing]

FIG. 1 is a spectral sensitivity curve of an electrophotographic photoreceptor according to the present invention. The first tabe likelihood factor, T4 width (71ff/cscg

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor containing an azo compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, A is a coupler residue, R is a hydrogen atom, an alkyl group,
or an aryl group, X and Y represent an optionally substituted carbocyclic or heterocyclic aromatic ring. )