JPH0695406A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity, low residual potential and excellent repetitive characteristics when repeatedly used 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, aryl or a 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 H, optionally substd. alkyl, aralkyl or aryl, each of R23 and R24 is optionally substd. alkyl, aralkyl or aryl and X is a group of atoms required to form a satd. 5- to 8-membered ring in combination with two C atoms of th indoline ring.

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 to 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 field of copying machines, printers, etc., photoconductors containing such an organic photoconductive compound 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, there are very few practically used function-separated type photoreceptors, and many required characteristics such as charging characteristics, sensitivity, residual potential, pre-exposure characteristics, and repetitive use characteristics. It is difficult to say that we are satisfied with everything. It can be said that these characteristics largely depend 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 a theoretical basis 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 present invention has been found to be effective by including a hydrazone compound represented by the general formula 2 as a charge transfer substance, and has 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 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 Chemical Formula 2, R ₂₁ and R ₂₂ represent a hydrogen atom, an optionally substituted alkyl group, an aralkyl group or an aryl group, and R ₂₃ and R ₂₄ are an optionally substituted alkyl group,
An aralkyl group and an aryl group are shown. X represents, together with the two carbon atoms of the indoline ring, a group of atoms required for forming a saturated 5- to 8-membered ring.

In the general formula 1, B represents a residue of a coupler which reacts with a diazo group. The structures represented by the general formulas (b-1) to (b-10) shown in Tables 1 and 2 are as follows. 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 heterocycle 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,
Chlorooxazolyl group, triazolyl group, piperidyl group, pyridyl group, kyrinor group, etc.). R ₃ represents an oxygen atom, a sulfur atom, —NH—, R ₄ and R ₅ represent a hydrogen atom, an optionally substituted alkyl group, a nitro group,
A methoxy group, an ethoxy group, an acetyl group, a cyano group and a halogen atom are shown. Z is a chain hydrocarbon necessary for forming 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. 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 borofluoride salt or 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 formulas 4 to 32, but the present invention is not limited thereto.

[0030]

[Chemical 4]

[0031]

[Chemical 5]

[0032]

[Chemical 6]

[0033]

[Chemical 7]

[0034]

[Chemical 8]

[0035]

[Chemical 9]

[0036]

[Chemical 10]

[0037]

[Chemical 11]

[0038]

[Chemical 12]

[0039]

[Chemical 13]

[0040]

[Chemical 14]

[0041]

[Chemical 15]

[0042]

[Chemical 16]

[0043]

[Chemical 17]

[0044]

[Chemical 18]

[0045]

[Chemical 19]

[0046]

[Chemical 20]

[0047]

[Chemical 21]

[0048]

[Chemical formula 22]

[0049]

[Chemical formula 23]

[0050]

[Chemical formula 24]

[0051]

[Chemical 25]

[0052]

[Chemical formula 26]

[0053]

[Chemical 27]

[0054]

[Chemical 28]

[0055]

[Chemical 29]

[0056]

[Chemical 30]

[0057]

[Chemical 31]

[0058]

[Chemical 32]

The electrophotographic photoreceptor 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. A surface layer may be provided to improve the temperature.

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, acrylic acid ester, a polymer or copolymer of a vinyl compound such as methacrylic acid ester, silicon 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 represented by polymethylmethacrylate, 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 were 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.

A well-known plasticizer may be used in the electrophotographic photosensitive member of the present invention in order to improve film-forming property, flexibility and mechanical strength.

Further, in the electrophotographic photoreceptor 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. may be further added and used alone or a mixed solvent of two or more kinds of solvents such as. Further, when coating on a drum, a dipping coating method or the like is used.

[0070]

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 Carbide) were mixed with 100 parts by weight of tetrahydrofuran, and dispersed together with glass beads for 2 hours by a paint conditioner. . 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 the hydrazone compound of Exemplified Compound 6 and a polycarbonate resin (K-1 manufactured by Teijin Chemicals Ltd.
300) 10 parts by weight is dissolved in 200 parts by weight of dichloromethane, and the solution is applied onto the coating film of the charge generating substance by an applicator and dried at 80 degrees for 60 minutes,
A charge transfer layer having a dry film thickness of 20 μ was formed.

The thus-prepared laminated electrophotographic photosensitive member was stored overnight at room temperature in a dark place, and then electrophotographic characteristics were evaluated by an electrostatic recording test apparatus (SP-428 manufactured by Kawaguchi Denki Co., Ltd.). The measurement conditions were as follows: corona applied voltage: -5 kV, static mode No. 3 (ie process speed 167 mm
Illumination (white light) illuminance: 2lux.
As a result, the charging potential was −715 V and the half-exposure amount was 1.2 lu.
It showed a very high sensitivity value of x.sec.

Next, this photoconductor was attached to an aluminum drum base tube, and the repeating characteristics of charging exposure were evaluated by a drum photoconductor 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 9 shows the measurement results of the surface potential after charging, that is, the charging potential, and the surface potential after removing the light, that is, the residual potential. It can be seen that the changes in charging potential and residual potential are extremely small.

[0075]

[Table 9]

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 as the charge transfer substance, Table 1 was used.
0 was used, and a laminated photoreceptor was prepared in the same manner as in Example 1 except that Comparative Compounds 33 and 34 were used, and the half-exposure amount of the photoreceptor and the repetition were measured under the same measurement conditions as in Example 1. The characteristics were tested. The results are shown in Table 11.

[0077]

[Chemical 33]

[0078]

[Chemical 34]

[0079]

[Table 10]

[0080]

[Table 11]

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 properties, particularly in stability of charging potential and residual potential due to repeated use.

Examples 7 to 11 and Comparative Examples 6 to 10 Example 1 was repeated except that the charge generating substance and the charge transfer substance were the exemplified compounds shown in Table 12 and the comparative compounds 35, 36 and 37. A laminated photoconductor was prepared in the same manner as in Example 1.
Under the same measurement conditions as above, the half-exposure amount of the photoconductor and the repeating characteristics were tested. The results are shown in Table 13.

[0083]

[Chemical 35]

[0084]

[Chemical 36]

[0085]

[Chemical 37]

In Chemical formula 35, Chemical formula 36, and Chemical formula 37, B ₁ ,
B ₂ and B ₃ each represent a coupler residue represented by the following Chemical formula 38.

[0087]

[Chemical 38]

[0088]

[Table 12]

[0089]

[Table 13]

[0090]

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.

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 each} represent a hydrogen atom, an optionally substituted alkyl group, an aralkyl group or an aryl group,
R ₂₃ and R ₂₄ represent an optionally substituted alkyl group, aralkyl group or aryl group. X represents, together with the two carbon atoms of the indoline ring, a group of atoms required for forming a saturated 5- to 8-membered ring. )