JPH03200972A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the photosensitive body having good durability and high sensitivity by incorporating a specific azo compd. and specific hydrazone compd. into a photosensitive layer provided on a conductive substrate. CONSTITUTION:The azo compd. expressed by formula I and the hydrazone compd. expressed by formula II are incorporated into the photosensitive layer 4 provided on the conductive substrate 1. In the formula I, A denotes a residual coupling group. In the formula II, R1 and R2 are an aryl group which may be substd.; R1 and R2 may be bonded directly or via a combination group; R3 is a hydrogen atom, halogen atom, aralkyl group or phenyl group which may be substd.; R4 and R5 denote an alkyl group, aralkyl group or aryl group which may be substd., at least one of which is an aryl group which may be sustd. The electrophotographic sensitive body which has the high sensitivity, is not deteriorated in performance against iterative use and has the excellent performance is obtd. in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a photoreceptor for electrophotography.

More specifically, the present invention relates to an electrophotographic photoreceptor in which a photosensitive layer on a conductive support contains a specific azo compound and a hydrazone compound.

[Conventional technology]

In recent years, organic photoreceptors using organic photoconductive materials have been used as photosensitive materials for electrophotography due to their non-polluting, processability, and
It has many advantages such as low cost, and various studies are being carried out. Among these, the function-separated photoreceptor, in which the charge generation function and the charge transport function are divided into separate substances, is easy to design materials in that it is possible to select and combine substances with each function from a wide range of materials. It is attracting attention from this point of view.

The characteristics required of the charge-generating substance contained in electrophotographic photoreceptors are: (1) The ability to efficiently absorb light irradiated onto the photoreceptor and generate electric charge, and (2) resistance to heat and light. For example, it must be sufficiently stable against

The characteristics required for charge transport materials are (1)
To rapidly transport the charge injected from the charge-generating substance, (2) To carry out sufficient charge transport even in a low electric field and not leave any residual charge, (3) To be sufficiently stable against heat, light, etc. Examples include:

In other words, the photoreceptor must have excellent sensitivity characteristics in order to obtain a reproduced copy image that is faithful to the original image, and is also resistant to light, heat, etc. received during the repeated charging, exposure, development, and transfer processes during copying. Stable durability is required. Also,
In recent years, in order to cope with high-speed copying, there has been a strong demand for photoreceptors with even higher sensitivity.

Various compounds have been studied and proposed as charge-generating substances and charge-transporting substances.

For example, as a charge generating substance, JP-A-53-13344
No. 5, JP-A-53-95033, JP-A-53-132
Azo compounds have been reported in publications such as No. 347. In addition, as the charge transport material, Japanese Patent Application Laid-open No. 55-46761,
Hydrazone compounds have been reported in publications such as JP-A-5552064 and JP-A-57-58156.

However, the current situation is that none of the conventionally proposed photoreceptors fully satisfies the characteristics required for a photoreceptor, and it has been desired to develop an even better photoreceptor.

[Problem to be solved by the invention]

An object of the present invention is to provide a highly sensitive photoreceptor with good durability.

[Means to solve the problem]

The present inventors have made extensive studies to solve the above problems, and
As a result, an electrophotographic photoreceptor using a tetrakisazo compound having a tetraphenylthiophene-1,1-dioxide skeleton as a charge-generating substance and a new hydrazone compound as a charge-transporting substance has high sensitivity and high durability. The present invention was based on the discovery that this material has excellent properties such as the following.

That is, in the photosensitive layer provided on the conductive support, an azo compound represented by the general formula (+) (in the formula, A represents a coupler residue) and a shell-like (II) (in the formula, , R1 and R7 are
It is an optionally substituted aryl group, and R1 and Rt may be bonded directly or through a linking group, R1 is a hydrogen atom, a halogen atom, an alkyl group, or an optionally substituted phenyl group. , R6 and R2 are an alkyl group, an aralkyl group, or an optionally substituted aryl group, and at least one of them is an optionally substituted aryl group. ) This is an electrophotographic photoreceptor characterized by containing a hydrazone compound represented by the following formula.

The tetrakisazo compound represented by the general formula (1) of the present invention mainly functions as a charge-generating substance, and the hydrazone compound represented by the -shell (II) mainly functions as a charge-transporting substance. has discovered that when these compounds are used in combination, a photoreceptor can be provided which has not only durability but also particularly excellent sensitivity. Although it is possible to infer various reasons why this combination is particularly excellent, it is extremely difficult to predict such factors at the state of the art in this field. The combination of the azo pigment-based charge-generating material and the hydrazone-based charge-transporting material represented by the general formula (I[) is based on a surprising discovery.

- In the shell (1), there are various types of coupler residues represented by A.

For example, the following a) to d) are exemplified.

a)-Shelled (I[) coupler residue X (wherein, X represents an optionally substituted hydrocarbon ring or an optionally substituted heterocycle, cyclic group, R1 is hydrogen, an optionally substituted alkyl group or an optionally substituted phenyl group, R is an optionally substituted hydrocarbon ring group, an optionally substituted heterocyclic group, or a substituted a styryl group which may be
R9 represents hydrogen, an optionally substituted alkyl group, or an optionally substituted phenyl group, and R6 and R7 may form a ring together with the carbon atoms bonded to them.)
- Shell-like (II) X is specifically a ring formed by condensation with a benzene ring to which a hydroxyl group and Y are bonded, such as a hydrocarbon ring such as a naphthalene ring or an anthracene ring;
Alternatively, heterocycles such as an indol ring, a carbazole ring, a benzocarbazole ring, and a dibenzofuran ring can be exemplified.

Further, when X has a substituent, examples of the substituent include a halogen atom such as a chlorine atom and a bromine atom, or a hydroxyl group.

The ring group for R1 or R8 is a hydrocarbon ring group such as phenyl group, naphthyl group, anthryl group, pyrenyl group, or pyridyl group, thienyl group, furyl group, indolyl group, benzofuranyl group, carbazolyl group, dibenzofuranyl group. Examples include heterocyclic groups such as the following, and examples of the ring formed by bonding R8 and R9 include a fluorene ring.

When R6 or R6 is a cyclic group having a substituent, the substituent is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, or a fluorine group. Examples include halogen atoms such as chlorine atoms and bromine atoms, halomethyl groups such as trifluoromethyl groups, dialkylamino groups such as dimethylamino groups and diethylamino groups, nitro groups, cyano groups, carboxyl groups, and esters thereof.

When R1 or R9 is a phenyl group, examples of its substituent include halogen atoms such as chlorine atom and bromine atom.

b) - Shell-like (IV) or (V) coupler residue $1
0 (In both formulas, R1° represents a substituted or unsubstituted hydrocarbon group.) Specifically, R1° is an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, or octyl group, or Examples include alkoxyalkyl groups such as methoxyethyl group and ethoxyethyl group.

C)-shell-like (Vl) camplar residue $1+g (wherein, R11 represents an alkyl group, carbamoyl group, carboxyl group, or an ester group thereof, and R1□ represents an optionally substituted hydrocarbon ring group) ,)11+g can be specifically exemplified by hydrocarbon ring groups such as phenyl group and naphthyl group, and when these groups have a substituent, methyl group, ethyl group, propyl group, butyl group can be used as the substituent. Alkyl groups such as methoxy, ethoxy, propoxy and butoxy groups, dialkylamino groups such as dimethylamino and diethylamino groups, halogen atoms such as chlorine and bromine, nitro and cyano groups, etc. I can give an example.

d) - Shell-like (■) or (■) coupler residue (in both formulas, Z represents an optionally substituted divalent group of a hydrocarbon ring or a divalent group of an optionally substituted heterocyclic ring) ) Specifically, Z is a divalent group of a monocyclic aromatic hydrocarbon such as an 0-phenylene group, an 0-naphthylene group, a peri
-naphthylene group, 1,2-anthraquinonylene group, 9.
A divalent group of a fused polycyclic aromatic hydrocarbon such as lO-phenanthrylene group, or a 3,4-pyrazolediyl group, 2
, 3-pyrimidinediyl group, 4.5-pyrimidinediyl group, 6.7-pyrimidazolediyl group, 5.6-penziξ
Examples include divalent heterocyclic groups such as a dazoldiyl group and a 6,7-chiralindiyl group. When these ring groups have a substituent, examples of substituents include alkyl groups such as methyl, ethyl, propyl, and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy; Examples include dialkyl abutyl groups such as a dimethylamino group and a dimethylamino group, halogen atoms such as a chlorine atom and a bromine atom, a nitro group, and a cyano group.

Among the coupler residues exemplified above, the photosensitivity is high;
The coupler residue represented by the above-mentioned -shell (I[[) is most preferred because intermediate raw materials are easily available and it can be produced at low cost.

Furthermore, in the -shell form (I[I), it is particularly preferable that X is condensed with the benzene ring to which the hydroxyl group and Y are bonded to form a naphthalene ring.

More specific examples of the tetrakisazo compound used in the present invention include those represented by the following structural formula.

In addition, the structural formula is shown only by the coupler residue portion in general formula (1).

CH3 OC2Hs CH3 H3 H3 Such a general tetrakisazo compound represented by 2N) can be produced by the method disclosed in International Publication No. 11087107736.

In R3 and R2 of the above-mentioned shell (I[), examples of the aryl group include a phenyl group and a naphthyl group, and when the aryl group has a substituent, the substituent may be a methyl group, an ethyl group, etc. Examples include alkyl groups, alkoxy groups such as methoxy groups and ethoxy groups, halogen atoms such as chlorine atoms and bromine atoms, and dialkylamino groups such as dimethylamino groups and diethylamino groups. Examples of the aromatic ring formed by RI and Rt together with the carbon atom to which R1 and R8 are bonded directly or through a linking group include fluorene, xanthine, thioxanthin, etc. e The halogen atom of R3 is a chlorine atom, bromine, etc. Examples include atoms,
Examples of the alkyl group include a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, an octyl group, etc. When R1 is a phenyl group having a substituent, the substituent is a methyl group, an ethyl group, etc. Examples include alkyl groups such as methoxy groups and ethoxy groups, halogen atoms such as chlorine atoms and bromine atoms, and dialkylamino groups such as dimethylamino groups and diethylamino groups. R4
Examples of the alkyl group in and R include a methyl group, ethyl group, linear or branched propyl group, pentyl group, hexyl group, and octyl group, and examples of the aralkyl group include benzyl group, phenethyl group, and naphthylmethyl group. Examples of the aryl group include a phenyl group and a naphthyl group. When R4 and US are aryl groups having a substituent, examples of the substituent include an alkyl group such as a methyl group and an ethyl group, a methoxy group, and an ethoxy group. Examples include alkoxy groups such as groups, halogen atoms such as chlorine atoms and bromine atoms, and dialkylamino groups such as dimethylamino groups and diethylamino groups.

More specific compounds that can be used in the present invention are shown in Table 1, but the compounds that can be used in the present invention are not limited thereto.

Among the compounds exemplified in Table 1, compounds that can be preferably used in the present invention are N081, N002, No. 5, No.
, 13, etc., particularly preferably N001, No.
2 etc. can be used.

The hydrazone compound represented by the -shell (n) can be synthesized, for example, as follows.

- an aldehyde compound represented by the shell (IX) (wherein Rt, Rg and R8 are the same as R1, h and R1 in the general formula (II)) and the general formula (X) HJ-N
Rs (X) 4 (wherein R4 and R1 are R4 in general formula (II)
and R1. ) It can be easily obtained by reacting the hydrazine compound represented by or its mineral acid salt in an appropriate solvent.

The hydrazine compound of general formula (X) is used in an equimolar amount or in a slight excess relative to the aldehyde, preferably 1.0 to 1.
A molar ratio of 2 is used. It can also be used in the form of a mineral acid salt such as a hydrazine compound phosate.

Solvents used include alcohols such as methanol, ethanol, methyl cellosolve, and ethyl cellosolve;
Examples include ethers such as tetrahydrofuran and 1,4-dioxane, glycols such as ethylene glycol and propylene glycol, N,N dimethylformamide, dimethyl sulfoxide, and acetic acid. The amount used is not particularly limited, and the reaction proceeds whether the reaction system is in a completely dissolved state or in a suspended state.

The reaction proceeds satisfactorily at room temperature without heating, but may be heated to accelerate the reaction.

Further, the reaction can be promoted by adding an acid catalyst to the reaction system. Examples of acids include organic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid.

Progress of the reaction can be monitored by thin layer chromatography and high performance liquid chromatography.

After the reaction is completed, the desired product can be taken out by filtering the precipitated crystals, or, if no crystals are precipitated, by diluting with water and collecting the resulting precipitate by filtration. The compound of the present invention with even higher purity can be obtained by recrystallization or column chromatography.

The electrophotographic photoreceptor of the present invention comprises a photosensitive layer on a conductive support containing a tetrakisazo compound represented by -shell (1) and a hydrazone compound represented by general formula (U). It is something. A typical configuration example of such a photoreceptor is shown in the first example.
As shown in FIG.

What is shown in FIG. 1 is a single-layer type photoreceptor in which a dispersion type photosensitive layer 4 in which a charge generating substance 2 and a charge transporting substance 3 are dispersed in a binder is provided on a conductive support 1. Figure 2 shows a laminated type photosensitive N4° consisting of a charge generation layer 6 in which a charge generation substance is dispersed in a binder and a charge transport layer 5 in which a charge transport substance is dispersed in a binder on a conductive support l. This is a laminated photoreceptor equipped with

In addition, there is a structure in which the charge generation layer and the charge transport layer are reversed. Any of the photoreceptors having the above structure is effective in the present invention, and the layer structure is selected depending on the type for positive charging or negative charging.

Examples of the conductive support used in the photoreceptor of the present invention include a metal plate made of aluminum, copper, zinc, etc., a plastic sheet or film made of polyester, etc., on which a conductive material such as aluminum or 5not is vapor-deposited;
Alternatively, conductive treated paper, resin, etc. may be used.

As binders, vinyl polymers such as polystyrene, polyacrylamide, and poly-N-vinylcarbazole, and condensation resins such as polyamide resins, polyester resins, epoxy resins, phenoxy resins, and polycarbonate resins are used. Any resin that is adhesive to the body can be used.

Conventionally known methods can be used to manufacture the photoreceptor. For example, in a laminated photoreceptor, fine particles of an azo compound are dispersed in a solution containing a binder, coated on a conductive support, and dried to obtain a charge generating layer. A charge transport layer can be produced by coating and drying. ! Other methods can also be used to create the load-generating layer. For example, there is a method of vacuum-depositing an azo compound, or a method of applying and drying a solution of an azo compound, but the former method is expensive, and the latter method uses organic amines such as ethylenediamine and n-butylaton, which are generally difficult to handle. Since there are some disadvantages in manufacturing, such as the above, the method of coating a fine particle dispersion of an azo compound is preferable. The coating method is carried out by conventional means, such as doctor blade, dipping, wire bar, etc. The optimum thickness of the photosensitive layer varies depending on the type of photoreceptor. Then, the thickness is preferably 3 to 50 μm, more preferably 5 to 30 μm.

In addition, in the photoreceptor shown in FIG. 2, the charge generation layer 6
The thickness is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm. This thickness is 0.011
If it is less than 1 m, charge generation will not be sufficient, and if it exceeds 5 μm, the residual potential will be high, which is not practical. Furthermore, the thickness of the charge transport layer 5 is preferably 3 to 50 II m.
, more preferably 5 to 30 μm, and this thickness is
If it is less than 3 μm, the amount of charge will be insufficient, and if it exceeds 50 μm, the residual potential will be high, which is not preferred in practice.

In the photoreceptor as shown in FIG. 1, the content of the tetrakisazo compound in photosensitive N4 is preferably 50% by weight or less,
More preferably, it is 20% by weight or less. The content of the hydrazone compound is preferably 10 to 95% by weight, more preferably 30 to 90% by weight. Further, in the photoreceptor shown in FIG. 2, the proportion of the tetrakisazo compound in the charge generation layer 6 is preferably 30% by weight, more preferably 50% by weight or more. Further, the proportion of the hydrazone compound in the charge transport layer 5 is preferably 10 to 95% by weight, more preferably 30 to 90% by weight, and if it is less than 10% by weight, charge transport is hardly carried out;
If it exceeds % by weight, the mechanical strength of the photoreceptor deteriorates, which is not practical.

The electrophotographic photoreceptor of the present invention contains, in addition to the tetrakisazo compound represented by formula (1) and the hydrazone compound represented by shell (II), a conductive support, a binder, etc. However, it may contain a charge-generating substance or a charge-transporting substance other than the shell-like compounds (1) and (II).

Further, if necessary, the photosensitive layer may contain known additives such as sensitivity improvers and durability improvers. and,
An intermediate layer can also be provided between the conductive support and the photosensitive layer. Moreover, a surface protective layer can also be provided on the photosensitive layer.

Other components of the photoreceptor of the present invention are not particularly limited as long as they have the functions.

[Action and effect]

According to the present invention, by using a combination of the tetrakisazo compound represented by the shell (1) and the hydrazone compound represented by the general formula (If), high sensitivity and repeated use can be achieved. It is possible to provide an electrophotographic photoreceptor with excellent performance that does not deteriorate in performance.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the embodiments of the present invention are not limited thereby.

Production Example N, 28.7 g of a triphenylamine compound represented by the following formula was dispersed in 200 m of N-dimethylformamide, and
15.6 g of phosphorus oxychloride was added dropwise at 5°C. After stirring at the same temperature for 1 hour, the temperature was raised to 70 to 75°C and stirred for 3 hours. After cooling to room temperature, the reaction solution was poured with 800 g of ice water.
d, and an aqueous sodium hydroxide solution was added to make it alkaline. After further stirring at room temperature for 1 hour, the precipitate was collected by filtration and dried.

Recrystallized from aqueous ethanol to give yellow crystals (sintered from 65°C). Aldehyde compound represented by the following formula 20.5
I got g. (Yield: 67%) 2.7 g of the above aldehyde compound and 165 g of 1.1-diphenylhydrazine hydrochloride were mixed and dissolved in 50% of N,N-dimethylformamide, and the mixture was stirred at room temperature for 3 hours. After confirming the disappearance of the raw material aldehyde compound, add 50ml of water.
! was added, and the resulting precipitate was collected by filtration and dried. The phase-forming acid is dissolved in a small amount of ethyl acetate, ethanol is added, and the resulting precipitate is filtered and dried to form a yellow powder (sintered from 92°C).
．． Obtained 0g. This product was confirmed to be Exemplified Compound 1 based on elemental analysis and infrared absorption spectrum.

In addition, the purity determined by high performance liquid chromatography is 99.9.
%Met.

Elemental analysis value CHN Calculated value (%) 87.52 5,67 6.81 Actual value (
%) 87.68 5,54 6.77 Example 1 A 5% casein solution dissolved in 1% ammonia water was applied to an aluminum plate using a wire bar, dried at 80°C for 3 hours, and a 0.1 μm intermediate After forming the layer, a polyester resin (trade name "Vylon 200" manufactured by Toyobo Co., Ltd.) is applied.
5 parts of Exemplified Compound A-9, 0.5 parts of Exemplary Compound A-9, and 50 parts of tetrahydrofuran were pulverized and mixed in a ball mill, and the resulting dispersion was applied onto the intermediate layer using a wire bar, and dried at 80°C for 20 minutes. , a charge generation layer of approximately llIm was formed.

On this charge generation layer, a solution prepared by dissolving 1 part of Exemplified Compound No. 1 and 1 part of polycarbonate resin (trade name "Panrai" K-1300, manufactured by Teijin Kakai) in 10 parts of chloroform was applied using a wire bar. The mixture was dried at .degree. C. for 30 minutes to form a charge transport layer having a thickness of about 18 .mu.m, thereby producing the laminated photoreceptor shown in FIG. 2.

Electrostatic copying paper test bag opening (Kawaguchi Electric Seisakusho model EPA
-8100), the photoreceptor was charged by corona discharge with an applied voltage of -6KV, the surface potential V at that time was measured, and then the surface potential at that time V2 was left for 2 seconds.
Then, with the surface illuminance of the photoreceptor at 51 ux, irradiate it with light from a halogen lamp (color temperature 2856°K), measure the time for the surface potential to reach 1/2 of Vt, and take half-reduction exposure. The quantity E1/2 (lux-see) was calculated.

Furthermore, the surface potential v1□, ie, the residual potential, was measured after 10 seconds of light irradiation.

Examples 2 to 16 Photoreceptors were prepared in the same manner as in Example 1 using the compounds of the present invention as charge-generating substances and charge-transporting substances, respectively.
I asked for 2. The combinations of charge generating substances and charge transporting substances used and the measurement results are shown in Table 2 together with the results of Example 1.

Comparative Example 1 A photoreceptor was prepared in the same manner as in Example 1 using an azo compound (CG-1) represented by the following structural formula as a charge-generating substance and Exemplified Compounds No. 2 as a charge-transporting substance. I asked for 2. The results are shown in Table 2.

Comparative Example 2 A photoreceptor was prepared in the same manner as in Example 1 using Exemplified Compound A-53 as a charge generating substance and a hydrazone compound (CT-1'') represented by the following structural formula as a charge transporting substance. 2 was determined.The results are shown in Table 2.

Comparative Example 3 CG-1 as charge generation material, CT as charge transport material
A photoreceptor was produced in the same manner as in Example 1 using El/
I asked for 2. The results are shown in Table 2.

Examples 17 to 20 The photoreceptors prepared in Examples 1, 2, and 8 were attached to a commercially available electrophotographic copying machine to make copies, but even on the 10,000th copy, a clear image without fogging that was faithful to the original was obtained. Ta.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing an example of the structure of an electrophotographic photoreceptor. In FIGS. 1 and 2, the respective symbols are as follows. Drawing 1--Electroconductive support 4,4°...Photosensitive layer 2--Charge generating substance 5--Charge transport layer 3-- Charge transport substance 6-・-
Charge generation layer patent distributor Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1) In the photosensitive layer provided on the conductive support, the general formula (
I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, A indicates a coupler residue.) Azo compounds represented by, and general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc. ▼(II) (In the formula, R_1 and R_2 are optionally substituted aryl groups, R_1 and R_2 may be bonded directly or through a linking group, and R_3 is a hydrogen atom, a halogen atom, or an alkyl group. group or an optionally substituted phenyl group, R_4 and R_5 are an alkyl group, an aralkyl group, or an optionally substituted aryl group,
At least one of them is an optionally substituted aryl group. ) An electrophotographic photoreceptor comprising a hydrazone compound represented by: