JPH0553349A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a high sensitivity and to obviate the deterioration in performance against iterative use by using a novel azo compd. as a charge generating material and a specific triphenyl amine compd. as a charge transfer material. CONSTITUTION:The azo compd. expressed by formula I is used as the charge generating material and the triphenyl amino compd. expressed by formula II is used as the charge transfer material of the electrophotographic sensitive body constituted by providing a photosensitive layer contg. the charge generating material and charge transfer material on a conductive base. In the formula I, Ar denotes bito quadrivalent atom. combination group; R<1> to R<3> respectively independently denote a hydrogen atom, halogen atom, 1 to 10C straight chain, branched or cyclic alkyl group, etc.; Y denotes a hydrogen atom, halogen atom, hydroxy group; X denotes an org. residual group forming an arom. hydrocarbon ring or arom. heterocycle by condensing with a benzene ring; n denotes integer 2 to 4. in the formula II, R<1> to R<6> respectively independently denote a hydrogen atom, halogen atom, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor. More specifically, it relates to an electrophotographic photoreceptor in which a photosensitive layer on a conductive support contains a specific azo compound as a charge generating substance and a specific triphenylamine compound as a charge transporting substance.

[0002]

2. Description of the Related Art In recent years, an organic photoconductor using an organic photoconductive material as a photosensitive material used for an electrophotographic photoconductor has many advantages such as no pollution, processability and low cost, and various studies have been conducted. .. Among them, the function-separated type photoconductor in which the charge generation function and the charge transport function are shared by different substances can be selected from a wide range of substances having each function, and can be combined, which facilitates material design. It is attracting attention from the point of.

The characteristics required of the charge generating substance contained in the electrophotographic photoreceptor are (1) a large ability to efficiently absorb the light applied to the photoreceptor and generate an electric charge, (2) It is sufficiently stable against heat and light. The properties required for the charge transport material are (1) to rapidly transport the charge injected from the charge generating material, (2) to sufficiently transport the charge even in a low electric field, and to prevent the charge from remaining. (3) It is sufficiently stable against heat and light. In other words, the photoconductor is required to have excellent sensitivity characteristics in order to obtain a copy image that is faithful to the original image and has good reproducibility. In addition, it is resistant to light, heat, etc., which are received in the repeating steps of charging, exposure, development and transfer 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 a photosensitive member with higher sensitivity.

Various compounds have been studied and proposed as charge generating substances and charge transporting substances.
As the charge generating substance, for example, JP-A-56-1677 is used.
59, JP-A-60-153050, JP-A-63-2
No. 64762 and the like are known. Examples of the charge transport material include, for example, JP-A-57-125941 and JP-A-57-5741.
No. 195254 and the like are known. In addition, JP-A-61
No. 132953 discloses a photoconductor using a trisazo pigment as a charge generating substance and a triphenylamine derivative as a charge transporting substance. Further, in JP-A-1-118147, a perylene compound as a charge generating substance, a charge transporting substance. And a azo compound represented by the following formulas (VI) to (VIII) (Chemical formula 6) as a charge generating substance in JP-A-2-272458.

[0005]

[Chemical 6] Photoconductors using a triphenylamine derivative as a charge transport material have been described, but these proposed photoconductors have a problem of charge generated in the charge generation material due to compatibility problems between the charge generation material and the charge transport material. The current situation is that the efficiency of injection into the charge transport material is poor and sufficient sensitivity has not been obtained as a photoreceptor. Further, conventionally proposed azo compounds have problems in durability, and photoreceptors using these compounds have poor durability, and further improvement has been desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly sensitive photoreceptor having good durability.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that as a charge generating substance, a novel azo compound having a coumarin skeleton with good durability and a charge transporting substance. The present inventors have found that an electrophotographic photoreceptor using a triphenylamine compound has excellent characteristics such as high sensitivity and high durability, and have reached the present invention.

That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer containing a charge-generating substance and a charge-transporting substance on a conductive support, as a charge-generating substance represented by the general formula (I) )

[0009]

[Chemical 7] (In the formula, Ar represents a divalent to tetravalent aromatic linking group,
R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms, or an aromatic heterocycle. Represents an alkoxycarbonyl group, an aryloxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a dialkylaminocarbonyl group, an arylaminocarbonyl group, a diarylaminocarbonyl group, an alkylarylaminocarbonyl group, a cyano group, Y is a hydrogen atom, It represents a halogen atom or a hydroxy group, X represents an organic residue which is condensed with a benzene ring to form an aromatic hydrocarbon ring or an aromatic heterocycle, and n represents an integer of 2 to 4. In addition to using the azo compound represented by the formula (1) as a charge transporting substance,

[0010]

[Chemical 8] (Wherein R ^{1 to} R ⁶ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a dialkylamino group, a diarylamino group, a cyano group, or a nitro group). The present invention relates to an electrophotographic photoreceptor, which is characterized by using.

The photoconductor of the present invention, that is, the photoconductor in which a novel azo compound as a charge generating substance and a triphenylamine compound as a charge transporting substance are combined is particularly excellent in sensitivity. Good compatibility of transport materials can be mentioned. It is possible to infer various causes, but it seems that it is extremely difficult to predict such factors in the state of the art in this field. However, surprisingly, the photoconductor of the present invention, which is a combination of the azo pigment type charge generating substance represented by the general formula (I) and the triphenylamine type charge transporting substance represented by the general formula (II), is excellent as a photoconductor. It has been found that it has different characteristics. Further, by using an azo compound having good durability, it was possible to obtain a photoreceptor having higher durability.

In the general formula (I), the aromatic linking group represented by Ar represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocycle which may be bonded via a linking group. The hydrocarbon ring may be benzene, naphthalene, anthracene, pyrene, phenanthrene, fluorene, anthraquinone, fluorenone, benzanthrone, etc., and the aromatic heterocycle may be thiophene, dibenzothiophene, pyridine, carbazole, benzoxazole, benzothiazole or the like. Can be mentioned. When it has a substituent, the substituent is an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group, an alkoxy group such as a methoxy group, an aryl group such as a phenyl group or a naphthyl group, a diethylamino group or diphenyl. Examples include substituted amino groups such as amino groups, halogen atoms such as fluorine atom, chlorine atom and bromine atom, hydroxyl group, nitro group and cyano group. Further, the aromatic hydrocarbon ring and the aromatic heterocycle may be bonded to each other via a bonding group.

[0013]

[Chemical 9] And so on. Specific examples of Ar that can be preferably used in the present invention are shown below (Chemical formulas 10 to 12).

[0014]

[Chemical 10]

[0015]

[Chemical 11]

[0016]

[Chemical formula 12] Specific examples of X in the general formula (I) include a hydrocarbon ring such as a naphthalene ring condensed with a benzene ring having an azo group bonded thereto, an anthracene ring, an indole ring, a carbazole ring,
Examples thereof include those that form a heterocycle such as a benzocarbazole ring and a dibenzofuran ring, and a naphthalene ring is particularly preferable as the generated ring. X may have a substituent, and examples of the substituent include halogen atoms such as chlorine atom and bromine atom, and hydroxyl group.

Azo compounds which can be preferably used in the present invention are specifically shown in Table 1 (Tables 1 to 3), Table 2 (Tables 4 and 5) and Table 3 (Table 6). In Ar in the table, (A-1) to (A-15) are the structural formulas shown above.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6] The tetrakisazo compound represented by the general formula (I) can be produced by the following method. That is, the general formula (VIIII)

[0024]

[Chemical 13] (In the formula, n represents the same meaning as in the general formula (I).) The amine compound represented by the general formula (X) is diazotized and then the diazotized compound is isolated as it is or as a borofluoride salt. ) (Chemical 14)

[0025]

[Chemical 14] (In the formula, R ¹ , R ² , R ³ , X and Y are represented by the general formula (I)
Has the same meaning as. It can be easily produced by coupling with a coupler compound represented by still,
The compound represented by the general formula (X) is represented by the general formula (XI)
5)

[0026]

[Chemical 15] (Wherein, X and Y have the same meanings as in formula (I)) and a compound of formula (XII)

[0027]

[Chemical 16] (Wherein R ¹ , R ² , and R ³ have the same meanings as in formula (I)) in the presence of PCl ₃ by heating in an aprotic solvent, or Alternatively, the compound of the general formula (XIII)

[0028]

[Chemical 17] (Wherein, X and Y have the same meanings as in formula (I)) and the compound of formula (XII) are reacted in the presence of a deoxidizing agent.

R ⁴ , R ⁵ , R ⁶ and R of the general formula (II)
Examples of the halogen atom represented by ⁷ , R ⁸ and R ⁹ include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom,
Examples of the alkyl group include a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, isopropyl group, t-butyl group, cyclopentyl group and cyclohexyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a 2-methylpropyloxy group.
Examples of the dialkylamino group include a dimethylamino group,
Examples thereof include a diethylamino group, a dipropylamino group, and a di (2-methylpropyl) amino group. Examples of the diarylamino group include a diphenylamino group, a ditoluylamino group, and a di (p-chlorophenyl) amino group. Can be mentioned.

General formula (II) which can be used in the present invention
Specific examples of the triphenylamine compound represented by are shown in Table 4 (Tables 7 to 9), but the compounds usable in the present invention are not limited thereto.

[0031]

[Table 7]

[0032]

[Table 8]

[0033]

[Table 9] The triphenylamine compound represented by the general formula (II) of the present invention can be synthesized, for example, as follows. General formula (XIV)

[0034]

[Chemical 18] (Wherein R ^{4 to} R ⁷ have the same meanings as in formula (II)) and the diphenylamine compound represented by formula (XV)

[0035]

[Chemical 19] (In the formula, R ⁸ and R ⁹ have the same meanings as in the general formula (II).) The iodobenzene compound can be easily obtained by carrying out the Ullmann reaction in the presence of copper and a deoxidizing agent. ..

The electrophotographic photoreceptor of the present invention comprises a tetrakisazo compound represented by the general formula (I) and a general formula (I
The triphenylamine compound represented by I) is contained in the photosensitive layer on the conductive support. A typical configuration example of such a photoreceptor is shown in FIGS. 1 and 2. FIG. 1 shows a single-layer type photosensitive member 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. The figure shows a laminated type photosensitive layer comprising a charge generating layer 6 in which a charge generating substance is dispersed in a binder on a conductive support 1, and a charge transporting layer 5 in which a charge transporting substance is dispersed in a binder.
It is a laminated type photoreceptor provided with 4 '.

In addition, the charge generation layer and the charge transport layer may be reversed. Any of the photoreceptors having the above-mentioned constitution is effective in the present invention, and the layer constitution is selected depending on the type for positive charging or negative charging.

The conductive support used in the photoreceptor of the present invention is a metal plate of aluminum, copper, zinc or the like,
A plastic sheet or plastic film made of polyester or the like, on which a conductive material such as aluminum or SnO ₂ is vapor-deposited, or paper or resin that has been subjected to a conductive treatment is used.

As the binder, vinyl polymers such as polystyrene, polyacrylamide and poly-N-vinylcarbazole, polyamide resins, polyester resins,
Condensation resins such as epoxy resins, phenoxy resins, and polycarbonate resins are used, but any resin that is insulative and has adhesion to the support can be used.

A conventionally known method can be used for producing the photoconductor. For example, in a laminated photoreceptor, fine particles of an azo compound are dispersed in a solution in which a binder is dissolved,
A charge generation layer is obtained by coating on a conductive support and drying,
Next, a solution in which a triphenylamine compound and a binder are dissolved is applied and dried to form a charge transport layer. Other methods can be used to make the charge generation layer. For example, there is a method of vacuum-depositing an azo compound, or a method of coating and drying a solution of an azo compound. In the former case, an organic amine, such as ethylenediamine or n-butylamine, which is expensive and generally inconvenient to handle, is used. The coating method of the fine particle dispersion liquid of the azo compound is preferable because it has drawbacks in production. The coating method is carried out by a conventional means, for example, doctor blade, dipping, wire bar or the like. The optimum thickness of the photosensitive layer varies depending on the type of the photoconductor. For example, in the photoconductor as shown in FIG. 1, the thickness is preferably 3 to 50 μm, more preferably 5 to 30 μm.

Further, in the photoconductor as shown in FIG.
The thickness of the charge generation layer 6 is preferably 0.01 to 5 μm, more preferably 0.05 to 2 μm. This thickness is 0.01μ
If it is less than m, the charge is not sufficiently generated, and if it exceeds 5 μm, the residual potential is high and it is not practically preferable. The thickness of the charge transport layer 5 is preferably 3 to 50 μm, more preferably 5 to 30 μm. If the thickness is less than 3 μm, the charge amount is insufficient, and if it exceeds 50 μm, the residual potential is high and it is practically used. Is not preferable.

In the photoreceptor as shown in FIG. 1, the photosensitive layer 4
The content of the tetrakisazo compound is preferably 50% by weight or less, more preferably 20% by weight or less. The content of the triphenylamine compound is preferably 10
˜95% by weight, more preferably 30 to 90% by weight. Further, in the photoreceptor as 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. The proportion of the triphenylamine compound in the charge transport layer 5 is preferably 10 to 95% by weight, more preferably 30 to 90%.
If it is less than 10% by weight, the charge is hardly transported, and if it exceeds 95% by weight, the mechanical strength of the photoreceptor is poor and it is not practically preferable.

The electrophotographic photoreceptor of the present invention contains a tetrakisazo compound represented by the general formula (I) and a triphenylamine compound represented by the general formula (II), a conductive support and a binder. Consists of
A charge generating substance or charge transporting substance other than the compounds of the general formulas (I) and (II) may be contained. If necessary, the photosensitive layer may contain known additives such as a sensitivity improver and a durability improver. Further, an intermediate layer can be provided between the conductive support and the photosensitive layer. A surface protective layer may be provided on the photosensitive layer. The other components of the photoconductor of the present invention are not particularly limited as long as they have the function.

[0044]

EXAMPLES The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereby. Example 1 A 5% casein solution dissolved in 1% ammonia water was applied to an aluminum plate with a wire bar and dried at 80 ° C. for 3 hours to form an intermediate layer of 0.1 μm. Next, polyester resin (trade name "Byron 200" manufactured by Toyobo)
0.5 part, 0.5 part of Exemplified Compound A-9 and 50 parts of tetrahydrofuran were pulverized and mixed by a ball mill, and the obtained dispersion was applied onto the intermediate layer using a wire bar, and the temperature was 80 ° C.
And dried for 20 minutes to form a charge generation layer of about 1 μm. A solution prepared by dissolving 1 part of Exemplified Compound No. 1 and 1 part of a polycarbonate resin (trade name "Panlite K-1300" manufactured by Teijin Kasei) in 10 parts of chloroform was applied onto the charge generation layer using a wire bar, and the temperature was 80 ° C. And dried for 30 minutes to form a charge transport layer having a thickness of about 18 μm, and the laminated type photoreceptor shown in FIG. 2 was produced. A photoconductor is charged by corona discharge with an applied voltage of -6 KV using an electrostatic copying paper tester (Model EPA-8100 manufactured by Kawaguchi Denki Seisakusho Co., Ltd.), and the surface potential V ₀ at that time is measured, and then for 2 seconds. It is left in the dark and the surface potential V ₂ at that time is measured. Further, the halogen lamp (color temperature 28
56 ° K) and the surface potential is 1/2 of V ₂
Is measured and the half exposure dose E1 / 2 (lux.
sec) was calculated. Also, the surface potential V after 10 seconds of light irradiation
₁₂ , the residual potential was measured.

Examples 2-35 Using the compounds of the present invention as a charge generating substance and a charge transporting substance, a photoconductor was prepared in the same manner as in Example 1, and E1 /
I asked for 2. The combination of the charge generating substance and the charge transporting substance used and the measurement results are shown in Table 5 together with the results of Example 1.
0, Table 11).

[0046]

[Table 10]

[0047]

[Table 11]

Comparative Example 1 The azo compound (CG-1) represented by the following structural formula (Formula 20) was used as the charge generating substance, and the compound No. 1 was used as the charge transporting substance. 2 was used to prepare a photoconductor in the same manner as in Example 1,
E1 / 2 was determined. The results are shown in Table 5 (Table 10 and Table 11).

[0049]

[Chemical 20]

Comparative Example 2 The azo compound (CG-2) represented by the following structural formula (Formula 21) was used as the charge generating substance, and the compound No. 1 was used as the charge transporting substance. 8 was used to prepare a photoconductor in the same manner as in Example 1,
E1 / 2 was determined. The results are shown in Table 5 (Table 10 and Table 11).

[0051]

[Chemical 21]

Comparative Example 3 The azo compound (CG-3) represented by the following structural formula (Formula 22) was used as the charge generating substance, and No. 1 was used as the charge transporting substance. Four
2 was used to prepare a photoconductor in the same manner as in Example 1, and E1 / 2
I asked. The results are shown in Table 5 (Table 10 and Table 11).

[0053]

[Chemical formula 22]

Examples 36 to 38 The photoconductors produced in Examples 1, 2, and 8 were mounted in a commercially available electrophotographic copying machine to perform copying, and even at the 10,000th sheet, the original image was vivid and clear without fog. An image was obtained.

[0055]

According to the present invention, by using the tetrakisazo compound represented by the general formula (I) and the triphenylamine compound represented by the general formula (II) in combination, high sensitivity and repeated use can be obtained. On the other hand, it is possible to provide an electrophotographic photoreceptor having excellent performance without performance deterioration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a single-layer type electrophotographic photosensitive member provided with a dispersion type photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder on a conductive support.

FIG. 2 is a layered electrophotography in which a charge-generating layer having a charge-generating substance dispersed in a binder and a charge-transporting layer having a charge-transporting substance dispersed in a binder are provided on a conductive support. FIG. 3 is a cross-sectional view of a photoconductor for use in the present invention.

[Explanation of symbols]

 1 Conductive Support 2 Charge Generating Material 3 Charge Transporting Material 4,4 'Photosensitive Layer 5 Charge Transporting Layer 6 Charge Generating Layer

Claims (4)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive support and a photosensitive layer containing a charge-generating substance and a charge-transporting substance, wherein the charge-generating substance is represented by the general formula (I): ] (In the formula, Ar represents a divalent to tetravalent aromatic linking group,
R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms, or an aromatic heterocycle. Represents an alkoxycarbonyl group, an aryloxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a dialkylaminocarbonyl group, an arylaminocarbonyl group, a diarylaminocarbonyl group, an alkylarylaminocarbonyl group, a cyano group, Y is a hydrogen atom, It represents a halogen atom or a hydroxy group, X represents an organic residue which is condensed with a benzene ring to form an aromatic hydrocarbon ring or an aromatic heterocycle, and n represents an integer of 2 to 4. In addition to using the azo compound represented by the formula (1) as a charge transporting substance, (In the formula, R ^{4 to} R ⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a dialkylamino group, a diarylamino group, a cyano group, or a nitro group.) An electrophotographic photosensitive member comprising a compound. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge generating substance is a diazo compound represented by the following general formula (III) (formula 3). [Chemical 3] (In the formula, R ¹ , R ² , R ³ , X, and Y have the same meanings as in formula (I).) 3. The electrophotographic photoreceptor according to claim 1, wherein the charge generating substance is a diazo compound represented by the following general formula (IV) (Chemical formula 4). [Chemical 4] (In the formula, R ¹ , R ² and R ³ have the same meanings as in formula (I).) 4. The electrophotographic photoreceptor according to claim 1, wherein the charge generating substance is a diazo compound represented by the following general formula (V) (Chemical formula 5). [Chemical 5] (In the formula, R ¹ , R ² and R ³ have the same meanings as in formula (I).)