JPS63169648A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the sensitivity of a sensitive body, to lower the residual potential and to prevent a change in the characteristics due to repeated use by incorporating a specified azo compd. into the photoconductive layer. CONSTITUTION:An azo compd. represented by the formula as a carrier generating substance is incorporated into a photoconductive layer on an electrically conductive support. In the formula, each of R1-R4 is H, carboxyl, alkoxyl, alkylcarbonyl, hydroxyl or the like and each of R5-R14 is -H, -CH3, -OCH3, -NO2, halogen or the like. The compd. is dispersed in a binder and applied to form the carrier generating layer of a separated function type sensitive body. The compd. may be used in a single layer type sensitive body. When the compd. is used, a sensitive body having high sensitivity, low residual potential and superior durability is obtd.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention relates to a photoreceptor for electrophotography. , those provided with a photosensitive layer mainly composed of an inorganic photoconductor such as zinc oxide or cadmium sulfide are widely known. However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In addition, selenium and cadmium sulfide in particular are toxic and have restrictions in manufacturing and handling. there were.

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. Poly-N-vinylcarbazole is well known as such an organic photoconductive compound, and the main component is a charge transfer complex formed between poly-N-vinylcarbazole and a Lewis acid such as 2,4,7-dolinitro-9-fluorenone. An electrophotographic photoreceptor having a photosensitive layer is described in Japanese Patent Publication No. 50-10'496. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability.

Furthermore, carrier (charge) generation function and carrier (charge)
Laminated type or dispersed type functionally separated type photoreceptors, in which the transfer function is assigned to separate substances, have a wide range of materials to choose from, and can be selected in terms of electrophotographic properties such as charging characteristics, sensitivity, and durability. It has the advantage that an electrophotographic photoreceptor having the following characteristics can be produced relatively easily.

Various carrier generation substances or carrier transfer substances have been proposed to be applied to the functionally separated photoreceptor, such as a carrier generation layer made of amorphous selenium and a carrier transfer substance mainly composed of poly-N-vinylcarbazole. An electrophotographic photoreceptor having a photosensitive layer that is a combination of layers has been put into practical use.

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 No. 47-37543 discloses an electrophotographic photoreceptor using a bisazo compound, JP-A No. 53-132347 uses a trisazo compound, and JP-A No. 49-11136 uses a phthalocyanine compound. Are listed. However, these photoreceptors are not necessarily satisfactory in terms of characteristics such as sensitivity, residual potential, and stability upon repeated use.

In addition, the selection range of carrier transfer substances is also limited, and the reality is that nothing that fully satisfies the wide range of requirements of electrophotographic processes has yet to be obtained.

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

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

[Structure of the invention]

(Means for Solving the Problems) To summarize the present invention, the present invention provides an electrophotographic photoreceptor in which a photoconductive layer is provided on a conductive support, and the photoconductive layer has the following general properties. The present invention relates to an electrophotographic photoreceptor characterized by containing a charge-generating azo compound represented by formula (I).

General formula: Hereinafter, the configuration of the present invention will be explained in detail.

The present invention is characterized in that the azo compound represented by the general formula (I) is used as a carrier generating substance for an electrophotographic photoreceptor. That is, the azo compound represented by the above general formula has excellent carrier generation ability, and the present invention utilizes the azo compound as a carrier for all functionally separated type electrophotographic photoreceptors in which carrier generation and transfer are performed using separate substances. It is used as a generating substance, and as a result, 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. Also, 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 compounds represented by the general formula (2) useful in the present invention using structural formulas include those shown in Table 1 below. It should be noted that this is merely an example and the invention is not limited thereto.

The azo compound represented by the general formula (I) useful in the present invention can be synthesized by a method known per se.

For example, 4,4'-phenylenediamines are converted into diazonium and reacted with pyrazolones as couplers to obtain azo compounds. Then, it is reacted with 2-hydroxy-4-naphthocarboxylic acids to form an azo-amide compound. Next, the desired azo compound can be prepared by using this product as a coupler and reacting it with a diazonium compound obtained from benzidine.

Alternatively, an amide compound is obtained by reacting 4,4'-phenylene diamines with 2-hydroxy-4-naphthocarboxylic acids. Next, it is converted into a diazonium, and this product is coupled with a pyrazolone to form an azo-amide compound. Next, using this product as a coupler, the desired azo compound can be prepared in the same manner as described above. A carrier-generating layer containing an azo compound represented by the general formula (I) as a carrier-generating substance as a main component and a carrier-transporting layer containing a carrier-transporting substance as a main component may be laminated on the support. However, a photosensitive layer in which a carrier transporting substance is dispersed in a carrier generating substance may be provided. Since these may be provided through an intermediate layer, the following patterns are possible.

■Support/carrier generation layer/carrier transport layer■Support/carrier transport Mg/carrier generation layer■Support/carrier transport layer containing carrier generating substance (a)Support/intermediate layer/carrier generation layer/carrier transport layer ■Support/intermediate layer/carrier transport layer/carrier generation layer■Support/intermediate layer/carrier transport layer containing a carrier generation substance Here, the intermediate layer refers to a barrier layer or an adhesive layer. It is also possible to provide a thin layer on the photoreceptor having the above structure for the purpose of surface protection or the like.

The conductive support used in the present invention is not particularly limited, and may be any support that is normally used as a conductive support for electrophotographic photoreceptors. Examples of such supports include metal materials such as brass, aluminum, gold, and silver; metals whose surfaces are coated with a thin film of plastic; metal-coated paper, metal-coated plastic sheets, or aluminum iodide, iodine Examples include glass coated with a conductive layer such as copper oxide, chromium oxide, or tin oxide. These are used as thin cylindrical sheets with appropriate thickness, hardness, and flexibility, and either the support itself is conductive or its surface is conductive, and has sufficient strength for handling. It is preferable that the

There are carrier transport materials that transport electrons and materials that transport holes, and either can be used to form the photoreceptor of the present invention.

The electrophotographic photoreceptor of the present invention can be manufactured in a conventional manner according to techniques known in the manufacture of photoreceptors using organic photoconductive materials. For example, the carrier generation layer can be prepared by forming the azo compound represented by the general formula (I) into fine particles in a suitable medium, adding a binder if necessary, and placing the azo compound on the conductive support directly or through an intermediate layer. or applied over an already formed carrier transport layer;
dry.

The fine particles in the two media need to be dispersed with a diameter of 5 microns or less, preferably 3 microns or less, optimally 1 micron or less.

When a binder is used, there are no particular limitations on the binder used, but a film-forming polymer compound that is hydrophobic, has a high dielectric constant, and is electrically insulating is preferable. Various thermoplastic or thermosetting synthetic resins can be suitably used. As will be readily understood, it is advantageous for the medium to have the ability to dissolve the binder. ■, ■, of the above pattern
The amount of the binder used in the carrier generation layer (1) and (2) is preferably in the range of 0.1 to 5 times the weight of the carrier generation substance.

The thickness of the carrier generation layer in the cases of patterns (1), (2), (2), (2) and (3) is in the range of 0.01 to 20μ, preferably in the range of 0.05 to 5μ.

The carrier transport layer in the cases (1), (2), (2), and (3) of the above patterns can be formed by dispersing or dissolving a carrier transporting substance in a suitable medium, coating it, and drying it. It is preferable to use a binder, unless the carrier transport material is one that also acts as a binder itself, such as poly-N-vinylcarbazole or polyglycidylcarbazole. The same type of binder as used for forming the layer can be used.

The amount of binder used is 0.2 to 5 of the carrier transport material.
Double weight is appropriate.

The film layer of the carrier transport layer has a thickness of 1 to 100 μm, preferably 5 to 50 μm.

On the other hand, in order to form the dispersed carrier generation-carrier transport layer of pattern (1), a carrier transport substance is dissolved or dispersed in the above-mentioned dispersion liquid for forming the carrier generation layer, and the solution is coated on the conductive support. do it. The carrier transport substance can be selected arbitrarily.

It is generally preferred to add a binder, except when using something that itself serves as a binder, as described above.

When an intermediate layer is provided between the conductive support and the above laminated or dispersed photosensitive layer, the intermediate layer contains a carrier generating substance,
One type or a mixture of two or more of carrier transport substances, binders, additives, etc., and also functions as an intermediate layer.
Commonly used materials can be used as long as they are not damaged. The film thickness is 10μ or less.

Preferably it is 1μ or less.

Other known techniques can be applied to the electrophotographic photoreceptor of the present invention. For example, the photosensitive layer may contain a sensitizer. A suitable sensitizer is.

Examples include Lewis acids and dyes that form charge transfer complexes with organic photoconductive substances. In addition, additives such as plasticizers, ultraviolet absorbers, antioxidants, lubricants, adhesion promoters, etc. may be added as necessary to improve film formability, flexibility, mechanical strength, etc. of the photosensitive layer. Other carrier-generating substances may be used as long as they do not impair the characteristics of the electrophotographic photoreceptor that is the object of the present invention.
A carrier transport substance may also be added.

In the present invention, ordinary coating methods can be used to form the charge generation layer, carrier transport layer, intermediate layer, or surface layer.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 1 part by weight of the compound N001 in Table 1 and polyvinyl butyral (manufactured by Block Chemical Co., Ltd., rSLE) were used as charge generating substances.
C-BMIJ) 1 part by weight was placed in 50 parts by weight of cyclohexane and thoroughly dispersed with a ball mill.
A dispersion liquid for coating was prepared. This dispersion was applied onto an aluminum plate using a wire coater and dried with hot air at 120° C. for 30 minutes to form a charge generation layer having a thickness of about 0.3 μm. Furthermore, 2 parts by weight of 9-ethylcarbazole-3-carboxaldehyde phenylmethylhydrazone and 5 parts by weight of polyarylate (manufactured by Unitika Co., Ltd., "rg-too") were added to 70 parts by weight of 1.1.2-trichloroethane. A solution dissolved in the above was applied and dried with hot air at 80° C. for 30 hours to form a charge transport layer with a thickness of 12 μm.

The electrophotographic photoreceptor produced in this way was evaluated for charging characteristics (initial value of photoreceptor surface potential when charged) using Paper Analyzer SP-428 (manufactured by Kawaguchi Electric Co., Ltd.).
And the photosensitivity (the amount of exposure necessary for the initial value of the surface potential to attenuate to 1/2) was measured. The results are shown in Table 2.

Examples 2 to 17' Photoreceptors were prepared in the same manner as in Example 1, except that compounds No. 17 of Table 2 were used as charge-generating substances, and the characteristics were measured in the same manner. The results are also shown in Table 2. Comparative Example 1 Photoreceptors were prepared in the same manner as in Examples 1 to 17, except that chlordiane blue was used as the charge generating substance, and the characteristics were measured in the same manner. The results are also shown in Table 2.

(The following is a blank space) [Effects of the Invention] The electrophotographic photoreceptor of the present invention contains a specific azo compound that is stable against heat and light and has excellent carrier generation ability in its photoconductive layer. It is stable against heat and heat, has high sensitivity, has a small residual potential, and has excellent durability such that these characteristics do not change even after repeated use.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photoconductive layer provided on a conductive support, characterized in that the photoconductive layer contains an azo compound represented by the following general formula (I). An electrophotographic photoreceptor. General formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) However, in the formula, R_1, R_2, R_3, and R_4 may be the same or different, and are hydrogen atoms, carboxyl groups, alkoxyl groups, alkylcarbonyl R_5, R_6 may be the same or different, and R_5 and R_6 may be the same or different. Well-H,
-CH_3, -C_2H_5, -OCH_3, -OC_
2H_5, -NO_2, -SO_3H, -OH, -CO
OH, a monovalent group selected from halogen atoms, R_7, R_8, R_9, R_1_0, R_1_1, R
_1_2, R_1_3, R_1_4 may be the same or different, -H, -CH_3, -C_2H_5, -OCH
_3, -OC_2H_5, -NO_2, -SO_3H,
Each represents a monovalent group selected from -OH, -COOH, and a halogen atom.