JPH05241360A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity, low residual potential and excellent repetitive characteristics at the time of repeated use in an electrophotographic process. CONSTITUTION:This electrophotographic sensitive body contains a disazo pigment represented by formula I as an electric charge generating material and a hydrazone compd. represented by formula II as an electric charge transferring material in the photosensitive layer. In the formula I, A is H, optionally substd. alkyl or aryl or an optionally substd. heterocyclic group, each of (m) and (n) is 0 or 1 and B is a residue of a coupler. In the formula II, each of R21 and R22 is optionally substd. alkyl, alkenyl, aralkyl or aryl or an optionally substd. heterocyclic group, at least one of R21 and R22 is optionally substd. alkenyl and each of R23 and R24 is H, halogen, optionally substd. alkyl or alkoxy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member having high sensitivity and excellent repeatability.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member,
Those having a photosensitive layer containing an inorganic photoconductor as a main component such as selenium, cadmium sulfide, zinc oxide, and silicon have been widely known. However, these are not always satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. Further, selenium and cadmium sulfide are particularly toxic and therefore, they are limited in production and handling.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally selenium photosensitive. It has many advantages such as superior thermal stability as compared with the body, and has received much attention in recent years.

As such an organic photoconductive compound,
Poly-N-vinylcarbazole is well known, and an electrophotographic photosensitive material having a photosensitive layer containing as a main component a charge transfer complex formed from this and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. The body is special Japanese Sho 50-10496
It is described in Japanese Patent Publication No. However, this photoreceptor was not always satisfactory in sensitivity, film-forming property and durability.

On the other hand, an electrophotographic photosensitive material containing a low molecular weight organic photoconductor in which a charge transfer agent typified by triphenylamines, stilbenes and hydrazones and a charge generating agent such as phthalocyanine and azo pigment are combined. The body is proposed. Combine these with a suitable binder,
Further, by combining a compound having a high charge generation ability and a compound having a high charge transfer ability, for example, as a laminated type photoreceptor, a compound having a sensitivity close to that of an inorganic photoreceptor such as selenium has also appeared. As a result, in the fields of copying machines, printers, etc., photoconductors containing such organic photoconductive compounds as a main component have made great progress.

The laminated or dispersed function-separated type photoconductor in which the charge generation function and the charge transfer function are shared by different substances has a wide selection range of each material, and the charging characteristics, sensitivity and durability are large. It has an advantage that an electrophotographic photosensitive member having arbitrary electrophotographic characteristics such as properties can be prepared relatively easily.

Conventionally, various substances have been proposed as charge generating substances or charge transfer substances. For example, an electrophotographic photoreceptor having a photosensitive layer in which a charge generation layer made of amorphous selenium and a charge transfer layer containing poly-N-vinylcarbazole as a main component are combined has been put into practical use. However, the charge generation layer made of amorphous selenium has a drawback of poor durability. Further, various proposals have been made to use an organic dye or pigment as a charge generating substance. For example, as an electrophotographic photoreceptor containing a monoazo pigment or a disazo pigment in a photosensitive layer, JP-B-48-30513, KAISHO No. 52-4241, JP-A No. 54-46558 and JP-B No. 56-11945 are already known.

However, very few functionally separated type photoconductors have been put into practical use, and many required properties such as charging property, sensitivity, residual potential, pre-exposure property, repetitive use property, etc. It is difficult to say that we are satisfied with everything. It can be said that these characteristics depend largely on the performance of each of the charge generating substance and the charge transfer substance, but it is also known that the selection of a suitable combination thereof is important, and many have been proposed. .. The reason is considered to be that such selection is not based on theoretical grounds but is made by trial and error.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a function-separated electrophotographic photosensitive member which has high sensitivity, has a small residual potential, and is excellent in stability when repeatedly used in an electrophotographic process. Especially.

[0010]

As a result of various studies to achieve the above object, the present inventor has found that the electrophotographic photoreceptor contains a disazo pigment represented by the general formula 1 as a charge generating substance. The inventors have found that it is effective to include a hydrazone compound represented by the general formula 2 as a charge transfer substance, and have reached the present invention.

The present invention relates to an electrophotographic photosensitive member comprising a conductive support and a photosensitive layer formed thereon. The photosensitive layer contains a disazo pigment represented by the general formula 1 as a charge generating substance, and a charge transfer substance. The electrophotographic photosensitive member is characterized by containing a hydrazone compound represented by the general formula 2.

In the chemical formula 1, A is a hydrogen atom, an optionally substituted alkyl group, an aryl group or a heterocyclic group, m and n are 0 or 1, and B is a coupler residue.

In the chemical formula 2, R ₂₁ and R ₂₂ each represent an optionally substituted alkyl group, alkenyl group, aralkyl group, aryl group or heterocyclic group. However, at least one of R ₂₁ and R ₂₂ is an optionally substituted alkenyl group. R ₂₃ and R ₂₄ represent a hydrogen atom, an optionally substituted alkyl group, an alkoxy group or a halogen atom.

In the general formula 1, B represents a residue of a coupler which reacts with a diazo group, and the structures represented by the general formulas (b-1) to (b-10) shown in Tables 1 and 2 The coupler residue of is particularly effective.

[0015]

[Table 1]

[0016]

[Table 2]

In Tables 1 and 2, Y is a polycyclic aromatic ring such as a naphthalene or anthracene ring condensed with a benzene ring or a heterocyclic ring such as a carbazole ring, a benzocarbazole ring or a dibenzofuran ring condensed with a benzene ring. The atomic groups necessary to form a ring are shown.

R ₁ is an optionally substituted alkyl group (eg, methyl group, ethyl group, n-propyl group, is
o-propyl group, n-butyl group, sec-butyl group, amyl group, 1-octyl group, benzyl group, p-chlorobenzyl group, 3,4-dichlorobenzyl group, p-methylbenzyl group, 2-phenyl Ethyl group, α-naphthylmethyl group, β-naphthylmethyl group, etc.), aryl group (for example,
Phenyl group, tolyl group, xylyl group, biphenyl group, chlorophenyl group, dichlorophenyl group, bromphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, phenoxyphenyl group, nitrophenyl group, cyanophenyl group, hydroxyphenyl group, Carboxyphenyl group, N, N-dimethylaminophenyl group,
α, α, α-trifluoromethylphenyl group, methylthiophenyl group, α-naphthyl group, β-naphthyl group and the like).

[0019] R ₂ is, R ₁ and Hajime Tamaki (e.g., a thiazolyl group, 5-Nitorochiazoriru group, a carbazolyl group, an indolyl group, a pyrrolyl group, acridyl group, benzo (b) thiophenyl, benzimidazolyl, oxazolyl, chloro Oxazolyl group, triazolyl group, piperidyl group, pyridyl group, kyrinor group, etc.). R ₃ represents an oxygen atom, a sulfur atom or —NH—, and R ₄ and R ₅
Represents a hydrogen atom, an optionally substituted alkyl group, a nitro group, a methoxy group, an ethoxy group, an acetyl group, a cyano group, or a halogen atom. Z is a chain hydrocarbon required to form a 5-membered ring or a 6-membered ring.

Specific examples of the disazo pigment represented by the general formula 1 and useful in the present invention include those having the structural formulas shown in Table 3, Table 4, Table 5, Table 6, Table 7 and Table 8, for example. However, the present invention is not limited thereto.

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

[0024]

[Table 6]

[0025]

[Table 7]

[0026]

[Table 8]

In the disazo pigment represented by the general formula 1, the divalent amino compound represented by the general formula 3 is azotized by a conventional method, and then the corresponding coupler is coupled in the presence of an alkali, or The diazonium salt of the divalent amino compound is once isolated in the form of a borofluoride salt or a zinc chloride double salt, and then isolated in a suitable solvent (eg, N, N-dimethylformamide, dimethyl sulfoxide, ethanol, dioxane, etc.). Thus, it can be easily synthesized by a coupling reaction with a coupler in the presence of an organic or inorganic alkali.

[0028]

[Chemical 3]

Next, specific examples of the hydrazone compound represented by the general formula 2 as the charge transfer substance in the present invention are shown in Tables 9 and 10, but the present invention is not limited thereto.

[0030]

[Table 9]

[0031]

[Table 10]

The electrophotographic photosensitive member according to the present invention contains the disazo pigment represented by the general formula 1 as a charge generating substance, and the hydrazone compound represented by the general formula 2 as a charge transfer substance. It is obtained by containing it and has excellent performance.

Hereinafter, each component of the present invention will be described in detail. First, as the electroconductive support on which the photosensitive layer of the photoconductor is formed, any of those known in electrophotographic photoconductors can be used. Specifically, for example, gold, silver,
Examples thereof include platinum, titanium, aluminum, copper, zinc, iron, drums, sheets, belts made of metal oxides or the like subjected to conductive treatment, laminates of these thin films, vapor depositions and the like.

Further, metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt,
Drums, sheets, belts, etc. made of plastic, ceramics, paper, etc., which have been coated with a conductive substance such as an ion-conductive polymer electrolyte together with a suitable binder and embedded in a polymer matrix and have been subjected to a conductivity treatment, such as Drums, sheets, belts and the like of plastics, ceramics, papers, etc., which are made conductive by containing such a conductive substance can be mentioned.

The photosensitive layer is composed of a single layer type in which a charge generating substance and a charge transfer substance are dispersed and mixed and confined in a binder, and a laminated type in which the charge generating substance and the charge transfer substance are separated and sealed in a binder. The present invention can be applied to any system, but it is preferably used in a system of a function-separated laminated photoreceptor in which the performances of the charge generating substance and the charge transfer substance are easily utilized to the maximum.

A blocking layer may be provided between the photosensitive layer and the conductive support in order to control the injection of charges from the photosensitive layer to the conductive support. You may provide a surface layer in order to improve.

In the function-separated laminate type photoreceptor, the charge generation layer is composed of a mixed system of at least the disazo pigment represented by the general formula 1 as a charge generation substance and a binder resin. As the binder resin, styrene, vinyl acetate, an acrylic acid ester, a polymer or copolymer of a vinyl compound such as methacrylic acid ester, a silicone resin,
Examples thereof include phenoxy resin, butyral resin, formal resin, phenol resin, polycarbonate, polyarylate, polyamide, polyimide and the like, thermosetting resin such as epoxy resin and urethane resin, and photocurable resin. The binder is 1 to 1000 parts by weight, preferably 1 to 40 parts by weight, relative to 100 parts by weight of the charge generating substance (the disazo pigment).
Used in the range of 0 parts by weight. The thickness of the charge generation layer is
0.1 to 20 μm is preferable.

The hydrazone compound represented by the general formula 2 is used as a charge transfer substance in the present electrophotographic photosensitive member. For example, it is contained in the charge transfer layer in a laminated electrophotographic photoreceptor. In this case, the charge transfer layer is composed of at least a hydrazone compound represented by the general formula 2 and a binder.

As the binder resin used in the charge transfer layer, polystyrene, acrylic resin typified by polymethyl methacrylate, polycarbonate having bisphenol A or Z skeleton, polyarylate, polyphenylene ether, polyether sulfone, polyamide, polyimide, A polyester resin or the like can be used.

In the charge transfer layer, 100 parts by weight of the charge transfer material (the hydrazone compound) and 10 parts by weight of the binder are used.
Used in the range of 1 to 400 parts by weight. The thickness of the charge transfer layer is preferably 5 to 100 μm.

The electrophotographic photoreceptor of the present invention preferably contains an antioxidant such as 2,6-ditertiarybutylparacresol and DL-α-tocopherol in order to prevent deterioration of the constituent organic compounds due to oxidation. .. In addition,
Well-known plasticizers may be used to improve flexibility and mechanical strength.

Further, in the electrophotographic photosensitive member of the present invention, the disazo pigment is used by dispersing it in a solvent and dissolving the binder and the charge transfer substance (the hydrazone compound). Solvents used are chloroform, dichloromethane,
Halogenated hydrocarbons such as dichloroethane, trichloroethane and trichlorethylene, aromatic hydrocarbons such as benzene, toluene and xylene, ethers such as dioxane, tetrahydrofuran and dimethoxyethane, cellosolves such as methyl cellosolve, dimethyl cellosolve and methyl cellosolve acetate. If necessary, a solvent such as alcohols, acetonitrile, N, N-dimethylformamide, methyl ethyl ketone, etc. can be further added and used as a solvent alone or a mixed solvent of two or more kinds of N. Further, when coating on a drum, a dipping coating method or the like is used.

[0043]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1 1 part by weight of a bisazo pigment of Exemplified Compound P-8 and 1 part by weight of a phenoxy resin (PKHJ manufactured by Union Carbite) were mixed with 100 parts by weight of dimethoxyethane, and dispersed together with glass beads for 2 hours by a paint conditioner. did.
The pigment dispersion thus obtained was applied onto an aluminum vapor-deposited film (Metal Me manufactured by Toray Industries, Inc.) with an applicator and dried at 80 ° C. for 15 minutes to form a charge generation layer having a thickness of about 0.2 μm.

Next, 10 parts by weight of a hydrazone compound of Exemplified Compound E-15 was added to a polyarylate resin (U-produced by Unitika Ltd.).
Polymer (10 parts by weight) and DL-α-tocopherol (0.2 parts by weight) are dissolved in dichloromethane (200 parts by weight), and the solution is applied onto the film of the charge generating substance by an applicator and dried at 80 ° C. for 60 minutes. Then, a charge transfer layer having a dry film thickness of 20 μm was formed.

The laminated electrophotographic photoreceptor thus prepared was stored at room temperature in a dark place for one day and then subjected to electrophotographic characteristic evaluation by an electrostatic recording tester (SP-428 manufactured by Kawaguchi Denki Co., Ltd.). The measurement conditions were as follows: corona applied voltage: -5 kV, static mode No. 3, illumination light (white light) illuminance: 2l
It was ux. As a result, the charging voltage was -715 V and the half-exposure amount was 1.4 lux · sec, which was a very high value.

Next, this photosensitive member was attached to an aluminum drum base tube, and the repeating characteristics of charging exposure were evaluated by a drum photosensitive member evaluation device (Cynthia 90 manufactured by Gentec Co., Ltd.). Measured voltage applied to corona: -5.2k
V, the process speed was 160 mm / sec, and the charging and photo-erasing were repeated 5000 times in the TCCD2 mode. Photostatic elimination was performed using a tungsten lamp array. Table 11 shows the measurement results of the surface potential after charging, that is, the charging potential, and the surface potential after photo-eliminating, that is, the residual potential. It can be seen that the changes in charging potential and residual potential are extremely small.

[0048]

[Table 11]

Examples 2 to 6 and Comparative Examples 1 to 5 Instead of the exemplified azo pigment P-8 as the charge generating substance and the exemplified hydrazone compound E-15 as the charge transfer substance,
A laminated photoreceptor was prepared in the same manner as in Example 1 except that the exemplified compounds shown in Table 12 and Comparative Compounds 4 and 5 were used, and the half exposure amount of the photoreceptor was measured under the same measurement conditions as in Example 1, and A repeatability test was performed. The results are shown in Table 13.

[0050]

[Chemical 4]

[0051]

[Chemical 5]

[0052]

[Table 12]

[0053]

[Table 13]

From these results, it can be seen that the photoconductors of the present invention shown in the examples are superior to the comparative examples in electrophotographic characteristics, particularly in stability of charging potential and residual potential due to repeated use.

Examples 7 to 11 and Comparative Examples 6 to 10 As Example 1 except that the charge generating substance and the charge transfer substance were the exemplified compounds shown in Table 14 and the comparative compounds of Chemical Formula 6, Chemical Formula 7, and Chemical Formula 8 respectively. A laminated photoconductor was prepared in the same manner, and the half-exposure amount of the photoconductor and the repeating characteristics were tested under the same measurement conditions as in Example 1. The results are shown in Table 15.

[0056]

[Chemical 6]

[0057]

[Chemical 7]

[0058]

[Chemical 8]

In Chemical formula 6, Chemical formula 7, and Chemical formula 8, B ₁ , B ₂ ,
B ₃ each represents a coupler residue represented by the following chemical formula 9.

[0060]

[Chemical 9]

[0061]

[Table 14]

[0062]

[Table 15]

[0063]

As is apparent from the above, according to the present invention, it is possible to provide an electrophotographic photosensitive member having high sensitivity, small residual potential and excellent repeating characteristics.

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[Procedure amendment]

[Submission date] June 1, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Chemical 1] (In Chemical formula 1, A is a hydrogen atom, an optionally substituted alkyl group, an aryl group, or a heterocyclic group, m and n are 0 or 1, and B represents a coupler residue.)

[Chemical 2] (In Chemical Formula 2, R ₂₁ and R ₂₂ represent an optionally substituted alkyl group, alkenyl group, aralkyl group, aryl group, or heterocyclic group, provided that at least one of R ₂₁ and R ₂₂ is substituted. It may also be an alkenyl group R ₂₃
And R ₂₄ represents a hydrogen atom, an optionally substituted alkyl group, an alkoxy group or a halogen atom. )

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028]

[Chemical 3]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

[0056]

[Chemical 6]

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, wherein the photosensitive layer contains a disazo pigment represented by the following general formula 1 as a charge-generating substance, and a charge-transporting substance. An electrophotographic photosensitive member comprising a hydrazone compound represented by the following general formula 2. [Chemical 1] (In Chemical Formula 1, A represents a hydrogen atom, an optionally substituted alkyl group, an aryl group, or a heterocyclic group, m and n are 0 or 1, and B represents a coupler residue.) ] (In Chemical Formula 2, R ₂₁ and R ₂₂ represent an optionally substituted alkyl group, alkenyl group, aralkyl group, aryl group, or heterocyclic group, provided that at least one of R ₂₁ and R ₂₂ is substituted. It may also be an alkenyl group R ₂₃
And R ₂₄ represents a hydrogen atom, an optionally substituted alkyl group, an alkoxy group or a halogen atom. )