JPH01222264A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To elevate sensitivity, sensitivity after repeated use, to reduce fluctuation of chargeability and optical fatigue, and to improve durability, of an electrophotographic sensitive body by using a specified azo compd. CONSTITUTION:A photosensitive layer contg. an azo compd. expressed by formula I is provided. In formula I, each R, R<1> is an H atom, halogen atom, etc.; each R<2> and R<3> is an alkyl group or an aralkyl group, etc.; A is an atomic group necessary for constituting a carbocyclic or heterocyclic aromatic ring. Said azo compd. is used as a photoconductive material for constituting such photoconductive layer or as a carrier generating material of a so-called function separating type electrophotographic sensitive body utilizing its superior carrier generating capacity. Thus, an electrophotographic sensitive body having stable characteristics such as superior film forming characteristic, charge holding capacity, sensitivity, residual potential, etc., generating scarce deterioration due to fatigue after repetitive use, nor generating no change in thermal and optical characteristics, is obtd.

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.

(B) Prior Art and its Problems Conventional electrophotographic photoreceptors have been widely known to have a photosensitive layer containing an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide as a main component.

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, and this and 2.4
．． An electrophotographic photoreceptor having a photosensitive layer containing as a main component a charge transfer complex formed from a Lewis acid such as 7-dolini-1, 9-fluorenone, etc. is described in Japanese Patent Publication No. 10496/1983. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability.

On the other hand, layered or dispersed function-separated 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 their charging characteristics, sensitivity, and durability are improved. 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 layer made of amorphous selenium and a carrier transfer layer mainly composed of poly-N-vinylcarbazole.

However, the carrier generation layer made of amorphous selenium has the disadvantage of poor durability.

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

For example, JP-A-47-37543 describes a bisazo compound, JP-A-53-132347 describes a trisazo compound,
JP-A-49-1'136 describes electrophotographic photoreceptors using phthalocyanine compounds. However, these photoreceptors have low sensitivity, residual potential,
Properties such as stability when used repeatedly are not necessarily satisfactory, and the selection range of the carrier movement function is also limited, so there is still no product that fully satisfies the wide range of requirements of the electrophotographic process. The reality is that this is not the case.

(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.

(D) Structure of the Invention In other words, the present invention clarifies that an electrophotographic photoreceptor characterized by having a photosensitive layer containing an azo compound represented by the following general formula (I) achieves the above object. This is what I did.

[In the formula, R, R1: hydrogen atom, halogen atom, alkyl group, alkoxy group, dialkylamino group, or cyan group (when m and n are 2 or more, they may be different from each other) R21R3: alkyl group, aralkyl group, An alkenyl group, an aryl group, or a heterocyclic group, each of which may have a substituent.

Further, R2 and the ring may form a ring.

m, n: an integer of 1 to 3 (X is a hydroxy group, -N R7R8 (R7, R8 are hydrogen atoms or alkyl groups), or -NH3OzR9 (
R9 is an alkyl group or an aryl group): Y is a hydrogen atom,
Halogen atom, alkyl group, alkoxy group, carboxyl group, carbamoyl group, or sulfamoyl group; Z is an atomic group necessary to constitute an optionally substituted carbocyclic or heterocyclic aromatic ring; R4 is hydrogen atom, amino group, carbamoyl group, carboxylalkyl or aryl group (B represents an optionally substituted phenylene group or naphthylene group). ] In the present invention, by using the azo compound of the general formula (■) as a photoconductive substance constituting the photosensitive layer of an electrophotographic photoreceptor, or by utilizing only its excellent carrier generation ability, so-called functions can be achieved. When used as a carrier-generating material in separate electrophotographic photoreceptors, it has excellent film physical properties and excellent electrophotographic properties such as charge retention, sensitivity, and residual potential.It also shows little fatigue deterioration even after repeated use, and is resistant to heat or light. It is possible to produce an electrophotographic photoreceptor that exhibits stable characteristics without any change in the above-mentioned characteristics.

Specific examples of the azo compound represented by the general formula (I>) include those having the following structural formula.

(Left below) υ■ U
(2) (Hereinafter in the margin) The azo compound described above can be easily synthesized by a known method.

Synthesis Example (Synthesis of Exemplified Compound (2)) 0.45 g of 2.7-diamitfluorenone-diphenylhydrazone dihydrochloride was dissolved in 20 wg of DMF, and 13 mff of 2N salt was added. This was cooled to 0°C, and an aqueous solution of 145my of sodium nitrite (2rri1
) and stirred at the same temperature for 50 minutes.

The obtained diazotized solution was added to a MF solution (20d) containing 0.60 g of 3-hydroxy-2-naphthoe[0-chloroanilide and 1.8 g of triethanolamine, and heated for 10 minutes at 0°C.
The mixture was added dropwise over a period of minutes, and stirred at the same temperature for 1.5 hours and then at room temperature for 1 hour. The precipitate was collected by filtration, DMFlood,
After washing with 100 d of water and 50 m of acetone, the exemplified compound (
0.83g of 2) was obtained. Note that mp>250'C.

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing an azo compound represented by the general formula (I). 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 in which an azo compound is dispersed in a binder ■ A photosensitive layer in which an azo compound is dispersed in a well-known charge transfer substance The azo compound represented by the above general 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 use 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, but both can be used in the photosensitive layer of the photoreceptor of the present invention, and a mixture of substances having the same type of function can be used. Also, mixtures of materials having different functions can be used. Electron transfer substances include nitro group, cyano group,
It is an electron-withdrawing compound having an electron-withdrawing group such as an ester group, and examples of these include nitrated fluorenone such as 2,4.7-titranitrofluorenone and 2.4.5.7-titranitrofluorenone; Or tetracyanoquinodimethane, tetracyanoethylene, 2,4゜5
．． Examples include compounds such as 7-titranitroxanthone and 2,4.8-trinidrothioxanthone, and polymerized versions of these electron-withdrawing compounds i.

In addition, 1. As a moving medium for holes, 1. For example, poly-N
- Polymers having a heterocyclic compound in the side chain as typified by vinylcarbazole, triazole derivatives, oxadiazole derivatives, pyrYlin derivatives, triarylamine derivatives, hydrazone derivatives, stilbene derivatives, and the like.

The charge transfer substance is not limited to those described herein, 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, an electrophotographic photoreceptor having a photosensitive layer of the type (2) described above can be prepared by coating a coating solution obtained by dispersing the azo compound represented by the general formula (I) in a suitable medium on a conductive support; It can be produced by drying and forming a photosensitive layer with a thickness of usually several to several tens of layers.

As a medium for preparing the coating solution, tetrahydrofuran, 1
, 4-dioxane, and other ethers: methyl ethyl ketone, cyclohexanone, and other ketones: toluene, xylene, and other aromatic hydrocarbons: N,N-dimethylformamide, acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, and other aprotic Polar solvent; methanol,
Alcohols such as ethanonyl and isopropanol; Esters such as ethyl acetate, methyl acetate, and methyl cellosolve acetate; Salts such as dichloroethane and chloroform;
:No::? A medium for dispersing an azo compound When using a medium for dispersing an azo compound, it is necessary to micronize the azo compound to a particle size of 511 nm or less, preferably 3 particles or less, and optimally 1 particle 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.

By dissolving a binder 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 the azo compound.
It is in the range of ~5 times the weight.

In addition, in forming this type of photosensitive layer,
The azo compound in the binder is fine, e.g. particle size 3II.
It is preferable that it exists in the form of fine particles of n or less, particularly 11IIIt 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 themselves can be used as binders, such as polyvinylcarbazole and polyglycidicarbazole, it is preferred to use binder 5 for others.

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. It is in the range of ~1.2 times the weight. In the case of a charge transport medium which itself can be used as a binder, it is usually used in amounts 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 coating solution obtained by dissolving a charge transfer medium in a suitable medium is applied onto the photosensitive layer of the types ① to ① above and dried to form a charge transfer layer, the photosensitive layer of the type ① will be obtained. 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 5-50I! It is the thickness of In. 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 chloranil, 2,3-dichloro-1,4-naphthoquinone, 2-methylanthraquinone, 1-nitroanthraquinone, 1-dichloro-5-nitroanthraquinone, 2-chloroanthraquinone, and phenanthrenequinone. quinones, aldehydes such as 4-nitrobenzaldehyde, 9-benzoylanthracene, indanedione, 3,5-dinitrobenzophenone, 3.3'.

5. Ketones such as 5'-tetranitrobenzophenone,
Acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride, cyanide compounds such as tetracyanoethylene, terephthalmalononitrile, and 4-nitrobenzalmalononitrile, 3-benzalphthalide, 3-(α-cyano-p- Examples include electron-withdrawing compounds such as phthalides such as nitrobenzal) phthalide.

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

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

Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known plasticizer 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.

Example 1 0.2 g of Exemplified Compound (2) and 0.2 g of polyarylate (Unideca U-'100) were added to 20 m of 1,2-dichloroethane and dispersed in a paint conditioner'- for 2 hours. The resulting dispersion was coated on an aluminum plate so that the film thickness after drying was 0.5 ptm and dried to form a carrier generation layer. difference .

In addition, a solution of 12 g of 4-(N,N-dibenzylamiver 2-methylbenzaldehyde-diphenylhydrazone and polyarylate (Unideca U-100>12 g) dissolved in 120 g of chlorobenzene was dried to have a film thickness of 20 I.
A carrier transfer layer was formed by coating and drying to obtain Ift, and an electrophotographic photosensitive material of the present invention was prepared. After this photoconductor was stored in a dark place at 30° C. overnight, it was mounted on an electrostatic paper tester rSP-428J (manufactured by Kawaguchi Denki Seisaku Shin), and all of the following characteristic tests were performed.

That is, a voltage of -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. 1゛Next, the light from a halogen lamp is irradiated with the illuminance on the surface of the photosensitive layer being 21uX, and the exposure is necessary to attenuate the surface potential of the photosensitive layer by 1/2! tEy(lux・
seconds) was calculated. Roughly speaking, using the same light source, the exposure amount required to lower the surface potential to -50V is 1: +o(lu
x seconds) was calculated.

The measurement of M was repeated 100 times and the results are summarized in Table 1.

Table 1 Comparative Example 1 A comparative photoreceptor was prepared in the same manner as in Example 1 except that the following compound was used as a carrier generating substance.

Measurements were carried out on this photoreceptor in the same manner as in Example 1, and the results shown in Table 2 were obtained.

Table 2 Example 2.3 A photoreceptor was prepared in the same manner as in Example 1, except that the following compound A or B was used as the carrier transport material.

Ejz This photoreceptor was measured in the same manner as in Example 1, and the results shown in Table 3 were obtained.

(The following is a blank space) Table 3 Examples 4 to 12 Photoreceptors were prepared and measured in the same manner as in Example 1, except that the compounds shown in Table 4 were used as carrier generating substances. The results are shown in Table 4.

(Leaving space below) Table 4 (F) Effects of the invention The photoreceptor using the azo compound of the invention has high sensitivity, and when used repeatedly, there is little change in sensitivity, chargeability, light fatigue, and durability. It is also extremely good.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photosensitive layer containing an azo compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼General formula (I) (where R, R^1: hydrogen atom, halogen atom, alkyl group, alkoxy group, dialkylamino group, or cyano group (m and n are 2 or more) may be different from each other)
] R^2, R^3: an alkyl group, an aralkyl group, an alkenyl group, an aryl group, or a heterocyclic group, each of which may have a substituent. Furthermore, R^2 and R^3 may form a ring. m, n: Integers from 1 to 3 A: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ Mathematical formulas, chemical formulas, tables, etc. There are ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (X is a hydroxy group, -NR^7R^8 (R^7 , R^
8 is a hydrogen atom or an alkyl group), or -NHSO_
2R^9 (R^9 is an alkyl group or an aryl group); Y
is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a carboxyl group, a carbamoyl group, or a sulfamoyl group; Z is an atomic group necessary to constitute an optionally substituted carbocyclic or heterocyclic aromatic ring :R^4 represents a hydrogen atom, an amino group, a carbamoyl group, a carboxyl group, or an ester group thereof; R^5 and R^6 represent an alkyl or aryl group; B represents an optionally substituted phenylene or naphthylene group) . ]