JPH0118417B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor in which a photosensitive layer comprising a combination of a carrier generation phase and a carrier transport phase is provided on a conductive support. To date, carrier generation layers (hereinafter referred to as ``CGL'') containing a carrier generation substance (hereinafter referred to as ``CGM'') that absorbs visible light and generates charged carriers (hereinafter simply referred to as ``carriers''). )
and a carrier transport layer (hereinafter referred to as "CTL") containing a carrier transport material (hereinafter referred to as "CTM") that transports either or both of the positive and negative carriers generated in this CGL. It has been proposed that a photosensitive layer of an electrophotographic photoreceptor can be constructed by combining these materials. in this way,
By assigning the two basic functions necessary for the photosensitive layer, carrier generation and transport, to separate layers, the range of materials that can be used in the composition of the photosensitive layer is widened, and each function can be optimized. By doing so, it becomes possible to independently select materials or material systems that achieve the desired properties in the electrophotographic process, such as a high surface potential when charged, a large charge retention ability, and a high resistance to light. It becomes possible to construct an electrophotographic photoreceptor having excellent characteristics such as high sensitivity and great stability in repeated use. Conventionally, as such a photosensitive layer, the following ones are known, for example. (1) Consisting of amorphous selenium or cadmium sulfide
A structure in which CGL and CTL made of poly-N-vinylcarbazole are laminated. (2) Consisting of amorphous selenium or cadmium sulfide
A structure in which CGL and CTL containing 2,4,7-trinitro-9-fluorenone are laminated. (3) A structure in which CGL made of a berylene derivative and CTL containing an oxadiazole derivative are laminated (see US Pat. No. 3,871,882). (4) A structure in which CGL made of chlordiane blue or methylscalyllium and CTL containing a pyrazoline derivative are laminated (Japanese Patent Application Laid-Open No. 1977-
(See Publication No. 90827). (5) CGL made of amorphous selenium or its alloy;
A structure in which CTL containing a polyarylalkane-based aromatic amino compound is laminated (patent application)
52-147251 specification). (6) A structure in which CGL containing a perylene derivative and CTL containing a polyarylalkane aromatic amino compound are laminated (Patent application 1983-
19907 specification). As described above, many types of photosensitive layers are known, but in conventional electrophotographic photoreceptors having such photosensitive layers, the electricity of the photosensitive layer when repeatedly subjected to electrophotographic processes is limited. It has the disadvantage of severe mechanical fatigue and a very short service life. For example, when the electrophotographic photoreceptor is repeatedly subjected to an electrophotographic process, the potential history state of the electrophotographic photoreceptor is not maintained stably, making it impossible to obtain stable image forming characteristics. Furthermore, the use of specific bisazo compounds as CGM has been disclosed in, for example, JP-A-55-117151 and JP-A-54-145142.
Even in combination with CTM, which is said to be able to be combined with CGM, the above-mentioned drawbacks are still considerable. As can be understood from this, a carrier transport substance that is effective against a specific carrier generating substance is not always effective against other carrier generating substances, and Nor can it be said that effective carrier generating substances are always effective against other carrier transport substances. If the combination of both substances is inappropriate, not only will the electrophotographic sensitivity become low, but also the discharge efficiency will be poor especially at low electric fields, so the so-called residual potential will increase.
In the worst case, potential accumulates each time it is used repeatedly, making it practically unusable for electrophotographic purposes. In this way, there is no legal way to select a suitable combination of the constituent substances of the carrier generation phase and the constituent substances of the carrier transport phase, and it is necessary to practically determine an advantageous combination from among many substance groups. . The present invention comprises a photosensitive layer consisting of a combination of a carrier generation phase and a carrier transport phase, has high sensitivity, and maintains a stable potential history state even when repeatedly subjected to an electrophotographic process. An object of the present invention is to provide an electrophotographic photoreceptor that can form good visible images. The above object is to provide an electrophotographic photoreceptor in which a photosensitive layer comprising a combination of a carrier generation phase and a carrier transport phase is provided on a conductive support, wherein the carrier generation phase has the following general formula [] or general formula [' ]
This is achieved by an electrophotographic photoreceptor containing a bisazo compound represented by the following formula, wherein the carrier transport phase contains a carbazole derivative represented by the following general formula []. General formula [] General formula [′] [In the formula, Ar ₁ , Ar ₂ and Ar ₃ are each a substituted or unsubstituted carbocyclic aromatic ring group, R ₁ or R ₂ is an electron-withdrawing group selected from a cyano group, a nitro group, or a halogen atom, respectively. , A:

【formula】

【formula】

【formula】

[expression] or

[Formula], X: hydroxy group,

[Formula] or -NHSO ₂ -R ₆ , (where R ₄ and R ₅ are hydrogen atoms, substitutions,
unsubstituted alkyl group, R ₆ is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group,) Y: hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, carboxyl group,
Sulfo group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted sulfamoyl group, (However, when m is 2 or more, mutually different groups may be used.) Z: Substituted or unsubstituted carbon ring Atom group necessary to constitute an aromatic ring or a substituted or unsubstituted heterocyclic aromatic ring, R ₃ : hydrogen atom, substituted or unsubstituted amino group, substituted,
An unsubstituted carbamoyl group, a carboxyl group or an ester group thereof, A': a substituted or unsubstituted aryl group, n: an integer of 1 or 2, m: an integer of 0 to 4. ] General formula [ ] [In the formula, R ₇ : substituted or unsubstituted aryl group, R ₈ : hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, amino group, substituted amino group, hydroxyl group, R ₉ : substituted or unsubstituted Represents a substituted aryl group, substituted or unsubstituted heterocyclic group. ] Among the bisazo compounds represented by the general formula [] or ['], preferred are those represented by the following general formula [a] or ['a]. General formula [a] General formula ['a] [In the formula, Ar ₁ , Ar ₂ , Ar ₃ and A: the same as defined in the general formula [] or the general formula [′]. ] More preferable ones are particularly the following general formula [b]
or ['b]. General formula [b] General formula ['b] In the formula, A: the same as defined in general formula [] or general formula ['], Ar ₄ , Ar ₅ and Ar ₆ represent substituted or unsubstituted phenyl groups, and the substituents include methyl group, Those selected from alkyl groups such as ethyl groups, alkoxy groups such as methoxy groups and ethoxy groups, halogen atoms such as chlorine atoms and bromine atoms, hydroxyl groups and cyano groups are preferred. ] That is, in the present invention, the bisazo compound represented by the above general formula [ ] or general formula ['] is
By using the carbazole derivative represented by the above general formula [] as a CGM and combining these as a CTM, a photosensitive layer of a so-called functionally separated photoreceptor in which carrier generation and transport are performed by separate substances, respectively, can be created. Configure. As a result, it is possible to provide an electrophotographic photoreceptor that has high sensitivity, maintains a stable potential history state even when subjected to repeated electrophotographic processes, and can therefore always form good visible images. . Further, in the electrophotographic photoreceptor of the present invention, a large spectral sensitivity can be obtained especially in the long wavelength range of 600 to 700 nm, and therefore, for example, a helium-neon laser with a wavelength of 6328 Å can be used as a light source for forming a latent image. Furthermore, when the electric field is low, the so-called potential termination is good, and the potential of the non-image area becomes zero or close to zero during development, so it is impossible to obtain a large effective bias using a one-component developer made only of toner. It is also possible to perform good development. Specific examples of the bisazo compound represented by the general formula [] include those having the following structural formula, but are not limited thereto. Exemplary compound Specific examples of the bisazo compound represented by the general formula ['] include those having the following structural formula, but are not limited thereto. Exemplary compound Specific examples of the carbazole derivative represented by the general formula [] include those having the following structural formula, but are not limited thereto. Exemplary compound Next, the mechanical structure of the electrophotographic photoreceptor of the present invention will be explained. In one example of the present invention, as shown in FIG. 1, CGL 2 containing the above-mentioned bisazo compound as a main component is formed on a conductive support 1, and the above-mentioned carbazole derivative is formed on this CGL 2. Formed by laminating CTL3 containing as the main component,
These CGL2 and CTL3 constitute a photosensitive layer 4. Here, as the material of the conductive support 1, for example, a sheet of metal such as aluminum, nickel, copper, zinc, palladium, silver, indium, tin, platinum, gold, stainless steel, or brass can be used. However, the invention is not limited to these. For example, as shown in FIG. 2, a conductive layer 1B may be provided on an insulating substrate 1A to constitute the conductive support 1. In this case, the substrate 1A may be Suitable materials include paper, plastic sheets, and other materials that are flexible and have sufficient strength against stress such as bending and tension. The conductive layer 1B can also be provided by laminating metal sheets, vacuum depositing metal, or by other methods. The above-mentioned CGL2 can be prepared by using the above-mentioned bisazo compound alone, by adding a suitable binder resin to it, or by adding a substance having high mobility to a specific or non-specific polar carrier, that is, CTM.
It can be formed by adding . As a specific method, a method is conveniently used in which the above-mentioned bisazo compound is dissolved or dispersed in a suitable solvent or dissolved or dispersed together with a suitable binder resin and then applied onto the support and dried. Ru. In this method, examples of the solvent or dispersion medium include n-butylamine, diethylamine,
Ethylenediamine, isopropanolamine, monoethanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, 1,2-dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol , ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, and others can be used. Examples of binder resins include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, etc. addition polymerization type resins, polyaddition type resins, polycondensation type resins, and copolymer resins containing two or more of the repeating units of these resins, such as vinyl chloride-vinyl acetate copolymer resins, vinyl chloride- In addition to insulating resins such as vinyl acetate-maleic anhydride copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazole can be used. The ratio of this binder resin to the bisazo compound is in the range of 0 to 100% by weight, particularly 0 to 10% by weight. An appropriate CTM may be added to the CGL2 as necessary. The thickness of the CGL 2 formed as described above is preferably 0.005 to 20 microns, particularly preferably 0.05 to 5 microns. If it is less than 0.005 microns, sufficient photosensitivity cannot be obtained, and if it exceeds 20 microns, sufficient charge retention cannot be obtained. Further, the CTL3 can be formed using the above-mentioned carbazole derivative in the same manner as the above-mentioned CGL2, that is, alone or together with a binder resin. Further, other CTMs may be included. The thickness of this CTL 3 is between 2 and 100 microns, preferably between 5 and 30 microns. The electrophotographic photoreceptor of the present invention may have other mechanical configurations. For example, as shown in FIG. 3, a suitable intermediate layer 5 is provided on a conductive support 1, a CGL 2 is formed through this, and a CTL 3 is formed on this CGL 2.
may be formed. This intermediate layer 5 has a function of preventing free carriers from being injected from the conductive support 1 into the photosensitive layer 4 when the photosensitive layer 4 is charged, or a function of preventing the photosensitive layer 4 from being integrally connected to the conductive support. It can function as an adhesive layer for adhering to. Materials for the intermediate layer 5 include metal oxides such as aluminum oxide and indium oxide, acrylic resins, methacrylic resins, vinyl chloride resins, vinyl acetate resins, epoxy resins, polyurethane resins, phenolic resins, polyester resins, alkyd resins, and polycarbonates. Polymeric substances such as resin, silicone resin, melamine resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, etc. can be used. Moreover, as shown in FIG. 4, on the conductive support 1,
The photosensitive layer 4 may be constructed by forming the CTL 3 with or without the intermediate layer 5 and forming the CGL 2 on the CTL 3. Furthermore, it is also possible to form a single-layer photosensitive layer by dispersing the above-mentioned bisazo compound in a carrier transport phase containing the above-mentioned carbazole derivative to form a carrier generation phase. In addition, various additives can be added to the layer constituting the photosensitive layer in the present invention, if necessary. Examples of the present invention will be described below, but the present invention is not limited thereto. Example 1 A conductive support made of polyethylene terephthalate with a thickness of 100 microns on which aluminum was vapor-deposited was coated with vinyl chloride-vinyl acetate-maleic anhydride copolymer "Eslec MF-10" (manufactured by Sekisui Chemical Co., Ltd.). An intermediate layer with a thickness of approximately 0.05 microns was provided, and 1.5 g of the bisazo compound shown as exemplified compound (-16) was added to the
The resulting dispersion was coated on the intermediate layer using a doctor blade and dried sufficiently to form a CGL with a thickness of about 0.5 microns.
was formed. On the other hand, 11.25 g of the carbazole derivative shown as exemplified compound (-16) and 15 g of polycarbonate resin "Panlite L-1250" (manufactured by Teijin Kasei) were mixed in 1,
It was dissolved in 100 ml of 2-dichloroethane, and the resulting solution was applied onto the CGL using a doctor blade and sufficiently dried to form a CTL with a thickness of 12 microns, thereby producing an electrophotographic photoreceptor of the present invention. .
This will be referred to as "Sample 1". Examples 2 to 8 Seven types of electrophotographic photoreceptors of the present invention were manufactured in the same manner as in Example 1, except that the combinations shown in Table 1 below were used as exemplary compounds in the formation of CGL and CTL. . These are each called “Sample 2”
~ "Sample 8".

【table】

[Table] Example 9 An intermediate layer was provided on a conductive support in the same manner as in Example 1, and 1.5 g of the bisazo compound shown as exemplified compound (--16) and polycarbonate resin "Panlite L-1250" were added. Add 15 g of 1,2-dichloroethane to 100 ml of 1,2-dichloroethane and disperse using a ball mill for 12 hours. The resulting dispersion was applied onto the intermediate layer using a doctor blade and thoroughly dried to form a CGL with a thickness of about 1 micron. Formed. CTL was formed on this CGL in the same manner as in Example 1, thereby producing an electrophotographic photoreceptor of the present invention. This will be referred to as "Sample 9." Example 10 In the formation of CGL, the bisazo compound shown in exemplified compound ('-5) was used,
An electrophotographic photoreceptor of the present invention was produced in exactly the same manner as in Example 9, except that the carbazole derivative shown in exemplified compound (-31) was used in the formation of CTL. This will be referred to as "Sample 10." Comparative Example 1 A comparative electrophotographic photoreceptor was produced in the same manner as in Example 1, except that a pyrazoline derivative having the following structural formula was used in place of the carbazole derivative in the formation of CTL in Example 1. This is referred to as "comparative sample 1." Comparative Example 2 A comparative electrophotographic photoreceptor was produced in the same manner as in Example 1, except that an oxadiazole derivative having the following structural formula was used in place of the carbazole derivative in the formation of CTL in Example 1. This will be referred to as "comparative sample 2." For each of the electrophotographic photoreceptors obtained as described above, Samples 1 to 10, Comparative Sample 1, and Comparative Sample 2, "Electrometer SP-428 Model" was used.
(manufactured by Kawaguchi Electric Seisakusho) to investigate its electrophotographic properties. In other words, the surface of the photoreceptor is charged with a voltage of -6KV.
The acceptance potential V _A (V) when charged for 5 seconds at 5
The potential V _I (initial potential) after dark decay for seconds is 1/2
The exposure amount E1/2 (lux・
seconds), and dark decay rate (V _A − V _I )/V _A ×100 (%)
I looked into it. The results are shown in Table 2.

【table】

[Table] From the results in Table 2, it is clear that the electrophotographic photoreceptor of the present invention has high sensitivity. In addition, each of Samples 1 to 10, Comparative Sample 1 and Comparative Sample 2 was transferred using a dry electronic copying machine "U-Bix2000R".
(manufactured by Konishiroku Photo Industry Co., Ltd.) to perform continuous copying, and measure the black paper potential V _b (V) and white paper potential V _W (V) at an exposure aperture value of 1.0 using an "electrostatic voltmeter 144D-1D model". (manufactured by Monroe Electronics, Inc.) and was measured immediately before development. The results are shown in Table 3. The black paper potential here refers to the surface potential of the photoreceptor when the above-mentioned copying cycle is performed using black paper with a reflection density of 1.3 as the original, and the white paper potential refers to the surface potential of the photoreceptor when the original is a blank paper. Represents surface potential.

【table】

[Table] As is clear from the results in Table 3, the electrophotographic photoreceptor of the present invention maintains a stable potential history state even when subjected to repeated electrophotographic processes.
A large number of visible images of good quality can be stably formed.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention, FIG. 2 is an explanatory sectional view showing another example of the structure of the electrophotographic photoreceptor of the invention, and FIGS. 3 and 4 2A and 2B are explanatory cross-sectional views showing still other structural examples of the electrophotographic photoreceptor of the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support, 2... Carrier generation layer (CGL), 3... Carrier transport layer (CTL), 4... Photosensitive layer, 5... Intermediate layer, 1A... Insulating substrate, 1B... Conductive layer.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor in which a photosensitive layer comprising a combination of a carrier generation phase and a carrier transport phase is provided on a conductive support, wherein the carrier generation phase has the following general formula [] or the general formula An electrophotographic photoreceptor comprising a bisazo compound represented by ['], wherein the carrier transport phase contains a carbazole derivative represented by the following general formula []. General formula [] General formula [′] [In the formula, Ar ₁ , Ar ₂ and Ar ₃ are each a substituted or unsubstituted carbocyclic aromatic ring group, R ₁ or R ₂ is an electron-withdrawing group selected from a cyano group, a nitro group, or a halogen atom, respectively. , A: [Formula] [Formula] [Formula] [Formula] or [Formula], where X: hydroxy group, [Formula] or -NHSO ₂ -R ₆ , [However, R ₄ and R ₅ are each a hydrogen atom , replacement,
unsubstituted alkyl group, R ₆ is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, ] Y: hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, carboxyl group,
Sulfo group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted sulfamoyl group, (However, when m is 2 or more, mutually different groups may be used.) Z: Substituted or unsubstituted carbon ring Atom group necessary to constitute an aromatic ring or a substituted or unsubstituted heterocyclic aromatic ring, R ₃ : hydrogen atom, substituted or unsubstituted amino group, substituted,
An unsubstituted carbamoyl group, a carboxyl group or an ester group thereof, A': a substituted or unsubstituted aryl group, n: an integer of 1 or 2, m: an integer of 0 to 4. ] General formula [ ] [In the formula, R ₇ : substituted or unsubstituted aryl group, R ₈ : hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkoxy group, amino group, substituted amino group, hydroxyl group, R ₉ : substituted or unsubstituted Represents a substituted aryl group, substituted or unsubstituted heterocyclic group. ]