JPH0251173B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor.
Specifically, the present invention relates to an electrophotographic photoreceptor having a photosensitive material containing a polyazo compound on a conductive support.

Conventionally, inorganic photoconductive substances such as selenium, cadmium sulfide, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors. In recent years, research on organic photoconductive materials has progressed, and some have been put into practical use as electrophotographic photoreceptors. Organic photoconductive materials have advantages over inorganic materials in that they are lighter in weight, easier to form into films, and easier to manufacture photoreceptors.

Many studies have been conducted on photoconductive polymers such as polyvinylcarbazole as organic photoconductive substances, but these polymers alone have poor film properties, flexibility, and adhesion, and it is difficult to improve these shortcomings. Plasticizers, binders, etc. are added to achieve this, but this tends to cause other problems such as decreased sensitivity and increased residual potential.
Practical application was extremely difficult.

On the other hand, with organic low-molecular photoconductive compounds, if a polymer with excellent film properties, flexibility, and adhesive properties is selected as a binder, it is possible to easily obtain a photoreceptor with excellent mechanical properties. It has been difficult to find compounds suitable for making sensitive photoreceptors.

In recent years, photoreceptors using specific monoazo compounds and bisazo compounds as photoconductive substances have been developed.
Although it is known from Japanese Patent Laid-Open No. 56-22438 and Japanese Patent Application Laid-Open No. 54-20736, the sensitivity of this type of photoreceptor is not necessarily sufficient for practical use, and further increase in sensitivity is desired.

Therefore, the present inventors conducted intensive research on organic low-molecular photoconductive compounds that provide electrophotographic photoreceptors with high sensitivity and high durability, and found that a specific polyazo compound is suitable. reached.

That is, the present invention provides an electrophotographic photoreceptor _in which a photosensitive layer containing a polyazo compound represented by the following general formula is provided on a conductive support. X, Y and Z each represent a substituted or unsubstituted aromatic hydrocarbon group, an aromatic heterocyclic group, or a group in which they are connected to each other directly or via C, N, O or S, and n is (Represents an integer from 3 to 11, and each of the n Y's may be the same or different.) Examples of the aromatic hydrocarbon group in the general formula of the polyazo compound used in the present invention include benzene. ,
Mono- or divalent residues obtained by removing one or two hydrogen atoms from aromatic hydrocarbons such as naphthalene, anthracene, pyrene, phenanthrene, acenaphthene indane, and tetralin can be mentioned, and aromatic heterocyclic groups include For example, mono- or divalent aromatic heterocycles with one or two hydrogen atoms removed, such as pyridine, pyrrole, thiophene, furan, oxazole, thiazole, pyrazole, imidazole, oxadiazole, benzofuran, indole, carbazole, quinoline, etc. The following residues can be mentioned.

The aromatic hydrocarbon group and the aromatic heterocyclic group may each have a substituent, and examples of the substituent include an alkyl group such as a methyl group and an ethyl group; an alkylene group such as a methylene group and an ethylene group; atom,
Halogen atoms such as bromine atoms; Alkoxy groups such as methoxy groups and ethoxy groups; Aryloxy groups such as phenoxy groups; Amino groups such as dimethylamino groups, diethylamino groups, phenylamino groups, and aminophenylamino groups; Methylthio groups, ethylthio groups Alkylthio groups such as nitro groups; alkyl ester groups such as methyl ester groups and ethyl ester groups; amide groups such as phenylamide groups, dimethoxyphenylamide groups, and chlorophenylamide groups; hydroxyl groups; oxo groups; phenyl groups, methoxyphenylamide groups; Examples include aromatic hydrocarbon groups such as an enyl group, methylphenyl group, and dinitrophenyl group; and aromatic heterocyclic groups such as a benzimidazolyl group.

Specific compounds corresponding to the above general formula are as follows.

The polyazo compound can be produced by a known method. For example, (1) a coupling reaction is performed between a tetrazonium salt of diamine represented by NH ₂ -Y-NH ₂ and an amine represented by Y-NH ₂ .
Producing a diamine represented by NH ₂ -Y-N=N-Y-N=N-Y-NH ₂ and, in some cases, further coupling a tetrazonium salt of the produced diamine with an amine represented by Y-NH ₂ By repeating the reaction, NH ₂ -(Y-N=N-) _o Y-NH ₂
A diamine represented by (n2) is produced, and then a tetrazonium salt of the produced diamine and X-H
and (2) a method of coupling a coupler compound represented by X-NH ₂ and Z-NH ₂ with an amine represented by Y-NH ₂ to form −N=N−Y−NH ₂ and Z−N=
By producing an amine represented by N-Y-NH ₂ and, in some cases, repeating a coupling reaction between the diazonium salt of the produced amine and the amine represented by Y-NH ₂ , X-(N=N- Y-)
_o NH ₂ (n1) and Z-(N=N-Y) _o NH ₂ (n
1), and then a coupling reaction is carried out between the diazonium salt of the produced amine and the coupler represented by H-Y-H. X in the reactions (1) and (2) above,
Y and Z have the same meanings as in the above general formula ().

The electrophotographic photoreceptor of the present invention can have various structures. Examples are shown in Figures 1-4. 1st
The photoreceptor shown in the figure has a photosensitive layer 2a formed by dispersing a polyazo compound 3 in a binder 4 on a conductive support 1.
It has been established. The photoreceptor shown in FIG. 2 has a photosensitive layer 2b formed on a conductive support 1, in which a polyazo compound 3 is dispersed in a charge transport medium 5 comprising a charge transport substance and a binder. The photoreceptor shown in FIGS. 3 and 4 has a photosensitive layer 2c or 2d consisting of a charge carrier generation layer 6 mainly composed of a polyazo compound 3, and a charge transport layer 7 composed of a charge transport substance and a binder.
are set up respectively.

In the case of the photoreceptor shown in Figure 1, polyazo compound 3
performs both the generation and transport of charge carriers necessary for optical attenuation. In the case of the photoreceptor of FIG. 2, the charge transport material together with the binder forms the charge transport medium 5, while the polyazo compound 3 acts as a charge carrier generating material. Although this charge transport medium 5 does not have the ability to generate charge carriers like a polyazo compound, it has the ability to accept and transport charge carriers generated from the polyazo compound. That is,
In the photoreceptor of FIG. 2, the generation of charge carriers necessary for light attenuation is carried out by the polyazo compound 3;
Transport of the charge carriers is primarily carried out by the charge transport medium 5. In the case of the photoreceptor shown in FIGS. 3 and 4, the polyazo compound 3 contained in the charge carrier generation layer 6 generates charge carriers, while the charge transport layer 7 receives charge carriers and transports them. . That is, the mechanism of action is the same as that of the photoreceptor shown in FIG. 2, in which charge carriers necessary for light attenuation are generated by the polyazo compound, and charge carriers are transported by a charge transport medium.

The photoreceptor shown in FIG. 1 can be produced by dispersing a polyazo compound in a binder solution, coating this dispersion on a conductive support, and drying it. Second
The photoreceptor shown in the figure can be produced by dispersing a polyazo compound in a solution containing a charge transporting substance and a binder, coating this dispersion on a conductive support, and drying it. The photoreceptor shown in FIG.
Alternatively, it can be produced by coating and drying a dispersion obtained by dispersing fine particles of a polyazo compound in a solvent or binder solution, and then coating and drying a solution containing a charge transport substance and a binder dissolved thereon. The photoreceptor shown in FIG. 4 can be prepared by applying a solution containing a charge transporting substance and a binder onto a conductive support, drying it, and then vacuum-depositing a polyazo compound thereon.
Alternatively, it can be produced by dispersing fine particles of a polyazo compound in a solvent or binder solution, applying a dispersion, and drying the resulting dispersion. Application is usually done using a roll coater, wire bar, doctor blade, etc.

The thickness of the photosensitive layer is 3 to 50 microns, preferably 5 to 20 microns in the case of the photoreceptors of FIGS. 1 and 2.
In the case of the photoreceptors shown in FIGS. 3 and 4, the thickness of the charge carrier generation layer is 0.5 to 5 μm, preferably 1 to 5 μm.
2μ, and the thickness of the charge transport medium layer is between 3 and 50μ, preferably between 5 and 20μ. In the photoreceptor shown in FIG. 1, the proportion of the polyazo compound in the photosensitive layer is 10 to 70% by weight, preferably 30 to 50% by weight, based on the photosensitive layer. In the photoreceptor shown in FIG. 2, the proportion of the polyazo compound in the photosensitive layer is 1 to 50% by weight, preferably 3 to 20% by weight, and the proportion of the charge transport material is 10 to 90% by weight, preferably 10% by weight. ~60% by weight. The proportion of the charge transport substance in the charge transport medium layer in the photoreceptor of FIGS. 3 and 4 is 10 to 95% by weight;
Preferably it is 10 to 60% by weight. In addition, 1st to 4th
In making any of the photoreceptors shown, a plasticizer can be used along with a binder.

As the conductive support for the photoreceptor of the present invention, for example, a metal plate or foil made of aluminum or the like, a plastic film on which a metal such as aluminum is vapor-deposited, or paper subjected to conductive treatment is 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.

In addition, well-known charge transport substances can be used, such as derivatives of heterocyclic compounds such as pyrazole, pyrazoline, oxadiazole, thiazole, and imidazole, hydrazone derivatives, triphenylmethane derivatives, poly-N-vinylcarbazole and its derivatives. etc. etc. Among these, pyrazole derivatives and hydrazone derivatives are particularly effective. Further, these charge transport materials can be used alone or in combination of two or more kinds.

In the photoreceptor obtained as described above, an adhesive layer or a barrier layer can be provided between the conductive support and the photosensitive layer, if necessary. Materials for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the film thickness is preferably 1 μm or less.

The photoreceptor of the present invention has excellent advantages such as very high sensitivity, small accumulation of residual potential and small fluctuations in surface potential and sensitivity due to repeated use, excellent durability, and high flexibility.

EXAMPLES The present invention will now be specifically explained with reference to Examples, and all "parts" in each example represent "parts by weight."

Example 1 One part of compound No. (7) listed in Table 1 above, phenoxy resin (trade name "PKHH", UNION (ARBIDE)
3 parts of a 10% dioxane solution and toluene,
A coating solution prepared by mixing 22 parts of a mixed solution of dioxane and ethyl cellosolve acetate (mixing ratio 4 parts/4 parts/2 parts) in a ball mill was applied onto an aluminum-deposited polyester film using a wire bar, dried, and then thickened. A charge generation layer with a thickness of 1 μm was formed. On this charge generation layer, 1 part of 3-(4-diethylaminostyryl)-S-(4-dimethylaminophenyl)-1-phenyl-2-pyrazole, a polycarbonate resin (trade name "Panlite L",
A coating solution prepared by dissolving 1 part (manufactured by Teijin Co., Ltd.) in 9 parts of methylene chloride was applied so that the film thickness after drying was 15 μm to form a charge transport layer, and an electrophotographic photoreceptor having the structure shown in Fig. 3 was prepared. Created. Using an electrostatic copying tester (product name "SPA28", manufactured by Kawaguchi Electric Seisakusho Co., Ltd.), the photoreceptor was first charged by corona discharge at an applied voltage of -6 KV in a dark place until the surface illuminance reached 5 lux. Expose to white light so that
The time (seconds) until the surface potential decreased to 1/2 of the initial surface potential was measured, and the photosensitivity E1/2 lux seconds was determined. The sensitivity of this photoreceptor was E1/2 = 2 lux seconds.

Comparative Example 1 For comparison with Example 1, compound No. 7 listed in Table 1 used in the same Example was replaced with A photoreceptor was prepared in the same manner as in Example 1 except that the diazo compound represented by was used. When measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E1/2 = 72 lux seconds.

Example 2 In Example 1, the charge transport layer was made of 10 parts of poly-N-vinicarbazole, 1.5 parts of O-terphenyl,
Picric acid 0.01 part and perchlorocyclodecane
A photoreceptor was prepared in the same manner except that it was formed using a coating solution in which 0.3 part of the photoreceptor was dissolved in 130 parts of a mixed solvent of toluene and dioxane (mixing ratio 1 part/1 part). Measurements were carried out in the same manner as in Example 1, and the sensitivity of this photoreceptor was E1/2 = 26 lux seconds.

Example 3 A photoreceptor was prepared in the same manner as in Example 1 except that coating liquids having the following compositions were used for the charge transport layer. When measured in the same manner as in Example 1,
The sensitivity of each photoreceptor was as follows.

(1)(A) Composition 2,4-bis(4-diethylaminophenyl)-1,3,4-oxadiazole 2 parts Phenoxy resin (trade name "PKHH") 3 parts Toluene/dioxane/ethyl cellosolve acetate mixed solvent (Mixing ratio 4 parts/4 parts/2
parts) 27 parts (b) Sensitivity E1/2 = 32 lux seconds (2) (a) Composition Bis(4-diethylamino-2-methylphenyl) phenylethane 1 part Phenoxy resin (trade name "PKHH") 1 part Toluene/Dioxane/ Ethyl cellosolve acetate mixed solvent (mixing ratio 4 parts/4 parts/2
part) 9 parts (b) Sensitivity E1/2 = 28 lux seconds (3) (a) Composition 4-diethylaminobenzylidene-1,1-
Diphenylhydrazine 1 part Phenoxy resin (trade name "PKHH") 1 part Toluene/dioxane/ethyl cellosolve acetate mixed solvent (mixing ratio 4 parts/4 parts/2
Part) 9 parts (B) Sensitivity E1/2 = 2 lux seconds Example 4 No. 1 prepared in the same manner as in Example 1.
A dispersion containing the compound No. 7 was applied onto a polyester film deposited with aluminum using a wire bar and dried to form a photosensitive layer having a thickness of 2 μm, thereby producing an electrophotographic photoreceptor having the structure shown in FIG. 1. The sensitivity of this photoreceptor was measured in the same manner as in Example 1 except that the surface illuminance was 100 lux, and it was found to be E1/2 = 9 lux seconds.

Example 5 1 part of compound No. 7 listed in Table 1, 10 parts of poly-N-vinylcarbazole, 0.3 parts of phenoxy resin (trade name "PKHH"), 140 parts of toluene, dioxane
A coating solution prepared by mixing 140 parts of ethyl cellosolve acetate and 5 parts of ethyl cellosolve acetate in a ball mill was applied onto an aluminum-deposited polyester film using a wire bar and dried to form a photosensitive layer with a thickness of 30 μm. An electrophotographic photoreceptor having this structure was created. When the sensitivity was measured in the same manner as in Example 4, the sensitivity of this photoreceptor was E1/2 = 11 lux seconds.

Example 6 A coating solution containing triphenylmethane prepared in the same manner as in Example 3 (2) was applied onto an aluminum-deposited polyester film using a wire bar and dried to form a charge transport layer with a thickness of 15μ. did.
On this charge transport layer, a coating solution containing compound No. 7 listed in Table 1 prepared in the same manner as in Example 1 was applied to a film thickness of 1 μm and dried to form a charge generation layer. An electrophotographic photoreceptor having the structure shown in FIG. 4 was prepared. When the sensitivity was measured in the same manner as in Example 1 except that the applied voltage was +6 KV, the sensitivity of this photoreceptor was E1/2 = 30 lux seconds.

Example 7 1 part of compound No. (29) listed in Table 1 above, 3 parts of a 10% dioxane solution of phenoxy resin (trade name "PKHH"), and a mixed solution of toluene, dioxane, and ethyl cellosolve acetate (mixing ratio of 4 parts) /4
A coating solution prepared by mixing 22 parts (part/2 parts) in a ball mill is applied onto an aluminum-deposited polyester film using a wire bar, dried, and the thickness is
A charge generation layer of 1μ was formed. On this charge generation layer, poly-N-
A charge transport layer was formed by applying a coating solution containing vinyl carbazole to a thickness of 15 .mu.m, thereby producing a photoreceptor having the structure shown in FIG. When measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E
1/2 = 30 lux seconds.

Comparative Example 2 For comparison with Example 7, instead of compound No. (29) listed in Table 1 used in the same example, A photoreceptor was prepared in the same manner as in Example 7 except that the diazo compound represented by was used. When the sensitivity was measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E1/2 = 75 lux seconds.

Example 8 A photoreceptor was prepared in the same manner as in Example 7 except that a coating solution containing triphenylmethane prepared in the same manner as in Example 4 was used for the charge transport layer.
When measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E1/2 = 34 lux seconds.

Example 9 1 part of compound No. (2) listed in Table 1, 10% dioxane solution of phenoxy resin (trade name "PKHH") 3
parts and toluene, dioxane, ethyl cellosolve acetate mixed solution (mixing ratio 4 parts/2 parts/2 parts)
A coating solution prepared by mixing 22 parts in a ball mill was applied onto an aluminum-deposited polyester film using a wire bar and dried to form a charge generation layer with a thickness of 1 μm. Example 3
A coating solution containing oxadiazole prepared in the same manner as above was applied to a film thickness of 15 μm and dried to form a charge transport layer, thereby producing a photoreceptor having the structure shown in FIG. When measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E1/2 = 24 lux seconds.

Comparative Example 3 For comparison with Example 9, instead of compound No. (2) listed in Table 1 used in the same example, A photoreceptor was prepared in the same manner as in Example 9 except that the diazo compound represented by was used. When the sensitivity was measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E1/2 = 75 lux seconds.

Example 10 A photoreceptor was prepared in the same manner as in Example 9 except that the charge transport layer was formed using a coating solution containing triphenylmethane prepared in the same manner as in Example 4. When measured in the same manner as in Example 1, the sensitivity of this photoreceptor was E1/2 = 14 lux seconds.

[Brief explanation of drawings]

1 to 4 are enlarged partial cross-sectional views of the electrophotographic photoreceptor of the present invention. 1... Conductive support, 2a, 2b, 2c, 2d
... Photosensitive layer, 3 ... Polyazo compound, 4 ... Binder, 5 ... Charge transport medium, 6 ... Charge carrier generation layer, 7 ... Charge transport layer.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing a polyazo compound represented by the following general formula, provided on a conductive support. X-(N=N-Y-) _o N=N-Z (in the formula, X, Y and Z are each substituted or unsubstituted aromatic hydrocarbon group, aromatic heterocyclic group, or they are directly connected to each other or , N, O or S, n represents an integer from 3 to 11, and each of the n Y's may be the same or different.)