JPH0325774B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor having a photosensitive layer formed by laminating a carrier generation layer and a carrier transport layer 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 to construct a photosensitive layer of an electrophotographic photoreceptor by laminating layers. 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 a CGL made of a perylene derivative and a CTL containing an oxadiazole derivative are laminated (see US Pat. No. 3,871,882). (4) A structure in which a CGL made of chlordiane blue or methylscalyllium and a CTL containing a pyrazoline derivative are laminated (Japanese Patent Application Laid-Open No. 1973-
(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). (6) A structure in which CGL containing a perylene derivative and CTL containing a polyarylalkane-based aromatic amino compound are laminated (Patent application 1973-
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 is disclosed in, for example, JP-A-55-117151, JP-A-54-145142, etc.;
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 layer and the constituent substances of the carrier transport layer, and it is necessary to practically determine an advantageous combination from among many substance groups. . The present invention comprises a photosensitive layer formed by laminating a carrier generation layer and a carrier transport layer, 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 always form good visible images. The above object is to provide an electrophotographic photoreceptor comprising a photosensitive layer formed by stacking a carrier generation layer and a carrier transport layer on a conductive support, in which the carrier generation layer is a bisazozoster represented by the following general formula []. This is achieved by an electrophotographic photoreceptor containing a styryl compound represented by the following general formula [], wherein the carrier transport layer contains a styryl compound represented by the following general formula []. General formula [] [In the formula, Ar ₁ and Ar ₂ are each a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group, R ₁ and R ₂ are each an electron-withdrawing group or a hydrogen atom , (However, at least one of R ₁ and R ₂ is an electron-withdrawing group), A:

【formula】

【formula】

【formula】

[expression] or

[Formula] It's hot, X: hydroxy group,

[Formula] or -NHSO ₂ -R ₆ (where R ₄ and R ₅ are hydrogen atoms, substituted,
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 or substituted or unsubstituted sulfamoyl group; Z: atomic group necessary to constitute a substituted or unsubstituted carbocyclic aromatic ring or substituted or unsubstituted heterocyclic aromatic ring; R ₃ : Hydrogen atom, substituted, unsubstituted amino group, substituted,
unsubstituted carbamoyl group, carboxyl group or ester group thereof; A': substituted or unsubstituted aryl group; n: an integer of 1 or 2; m: an integer of 0, 1 or 2. ] General formula [ ] [In the formula, _R7 and _R8 : substituted or unsubstituted phenyl group, _R9 : substituted or unsubstituted aryl group, heterocyclic group, _R10 to _R13 : hydrogen atom, halogen atom,
Represents an alkyl group, an alkoxy group, or an alkylamino group. ] Among the bisazo compounds represented by the general formula [], preferred are those represented by the following general formula [a] or [b]. General formula [a] [In the formula, R ₁ , R ₂ and A: the same as defined in the general formula [ ], R ₁₄ and R ₁₅ : alkyl group, alkoxy group or hydrogen atom, R ₁₆ and R ₁₇ : hydrogen atom or electron-withdrawing Represents an atom or group. ] General formula [b] [In the formula, A: the same as defined in the general formula, R ₁₄ and R ₁₅ each represent an alkyl group, an alkoxy group, or a hydrogen atom, R ₁₈ : an electron-withdrawing atom or group. ] That is, in the present invention, a bisazo compound represented by the above general formula [] is used as a CGM, and a styryl compound represented by the above general formula [] is used as a CTM to produce a CGL containing these.
By laminating CTL and CTL, a photosensitive layer of a so-called functionally separated photoreceptor is constructed in which carrier generation and transport are performed using separate substances. 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. . Furthermore, in the electrophotographic photoreceptor of the present invention, a large spectral sensitivity can be obtained particularly 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 edge of the potential is well cut, and the potential of the non-image area becomes zero or close to zero during development. 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. Specific examples of the styryl compound represented by the general formula [] include those having the following structural formula, but are not limited thereto. In the combination of a bisazo compound and a styryl compound exemplified above, when R ₁₄ or R ₁₅ in the general formula [a] or general formula [b] described above as the bisazo compound is an atom or group other than a hydrogen atom, Specifically speaking, if the phenylene ring group bonded to the carbon atom bonded by a double bond is a substituted phenylene ring group,
Compared to the case where the material is unsubstituted, the potential decrease tendency in the potential history when repeatedly subjected to electrophotographic processes is small, and good repeatability characteristics can be obtained. The reason for this is not clear, but by introducing a substituent to the phenylene ring group,
This is presumed to be due to the fact that the ionization potential becomes close to that of the styryl compound represented by the general formula [], and the energy levels can be matched. 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, a CGL 2 containing the above-mentioned bisazo compound as a main component is formed on a conductive support 1, and the above-mentioned styryl compound is formed on this CGL 2. It is formed by laminating CTL3 containing as a main component, and the photosensitive layer 4 is constituted by these CGL2 and CTL3. 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 an appropriate solvent or dissolved or dispersed together with an appropriate binder resin and then applied onto the support and dried. . Examples of the binder resin 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, and melamine resin. 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-vinyl acetate copolymer resins, etc. 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 CTL 3 can be formed using the styryl compound described above in the same manner as the CGL 2 described above, 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 have a 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, Polymer materials such as polycarbonate resin, silicone resin, melamine resin, vinyl chloride-vinyl acetate copolymer resin, and vinyl chloride-vinyl acetate-maleic anhydride copolymer resin can be used. Further, 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. 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 0.1 micron was provided, and 2 g of the bisazo compound shown as Exemplified Compound (-55) was added to 100 ml of 1,2-dichloroethane for 12 hours.
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 styryl compound shown as exemplified compound (-18) and 15 g of polycarbonate resin "Panlite L1250" (manufactured by Teijin Kasei) were mixed with 1,2-
Dissolve in 100 ml of dichloroethane, apply the resulting solution onto the CGL using a doctor blade,
Dry thoroughly to form a 12 micron thick CTL.
An electrophotographic photoreceptor of the present invention was thus manufactured. This will be referred to as "Sample 1". Examples 2 to 4 Exemplary compounds (-5), (-57) and (-61) as bisazo compounds in the formation of CGL
Three types of electrophotographic photoreceptors of the present invention were manufactured in exactly the same manner as in Example 1, except that each of the materials shown in . These are referred to as "Sample 2,""Sample3," and "Sample 4," respectively. Example 5 An electrophotographic photoreceptor of the present invention was produced in the same manner as in Example 1, except that exemplified compound (-21) was used as the styryl compound in forming CTL. This will be referred to as "Sample 5." Example 6 2 g of the bisazo compound shown as Exemplified Compound (-55) was added to 100 ml of 1,2-dichloroethane and dispersed for 12 hours using a ball mill. A CGL with a thickness of 0.5 microns was formed, and a CTL with a thickness of about 12 microns was formed in the same manner as in Example 1 using the styryl compound shown in exemplified compound (-12). manufactured the body. This will be referred to as "Sample 6". Comparative Example 1 A comparative electrophotographic photoreceptor was produced in the same manner as in Example 1, except that in the formation of CTL in Example 1, a pyrazoline derivative having the following structural formula was used instead of the styryl compound. This will be 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 a pyrazoline derivative having the following structural formula was used in place of the styryl compound in the formation of CTL in Example 1. This will be referred to as "comparative sample 2." Comparative Example 3 A comparative electrophotographic photoreceptor was produced in the same manner as in Example 1, except that in the formation of CTL in Example 1, an oxadiazole derivative having the following structural formula was used instead of the styryl compound. This will be referred to as "comparative sample 3." For each of the electrophotographic photoreceptors obtained as described above, Samples 1 to 6, and Comparative Samples 1 to 3, an electrometer SP-428 type was used.
(manufactured by Kawaguchi Electric Seisakusho) to investigate its electrophotographic characteristics. In other words, the surface of the photoconductor 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 1.

【table】

[Table] From the results in Table 1, it is clear that the electrophotographic photoreceptor of the present invention has high sensitivity. In addition, each of Samples 1 to 6 and Comparative Samples 1 to 3 was transferred using a dry electronic copying machine "U-Bix2000R".
(manufactured by Konishiroku Photo Industry Co., Ltd.) for continuous copying, and the black paper potential Vb (V) at an exposure aperture value of 1.0.
and white paper potential Vw (V) using "Electrostatic Voltmeter Model 144D-1D" (manufactured by Monroe Electronics Incorporated).
Measurement was made immediately before development. The results are shown in Table 2. The black paper potential here refers to the surface potential of the photoreceptor when the above-mentioned copying cycle is performed using a 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 black paper with a reflection density of 1.3. Represents surface potential.

[Table] (However, in the table, ΔVb (V) and ΔVw (V) indicate the amount of variation in the black paper potential Vb (V) and white paper potential Vw (V), respectively, and + in the variation amount indicates an increase, and - indicates a decrease. As is clear from the results in Table 2, 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. 1... Conductive support, 2... Carrier generation layer (CGL), 3... Carrier transport layer (CTL), 4...
Photosensitive layer, 5... Intermediate layer, 1A... Insulating substrate, 1
B... Conductive layer.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer formed by laminating a carrier generation layer and a carrier transport layer on a conductive support, wherein the carrier generation layer is represented by the following general formula []. 1. An electrophotographic photoreceptor, characterized in that the carrier transport layer contains a styryl compound represented by the following general formula []. General formula [] [In the formula, Ar ₁ and Ar ₂ are each a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group, R ₁ and R ₂ are each an electron-withdrawing group or a hydrogen atom (However, at least one of R ₁ and R ₂ is an electron-withdrawing group), A: [Formula] [Formula] [Formula] [Formula] or [Formula], and X: hydroxy group, [Formula] or - NHSO ₂ −R ₆ [However, R ₄ and R ₅ are hydrogen atoms, substituted,
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 or substituted or unsubstituted sulfamoyl group; Z: atomic group necessary to constitute a substituted or unsubstituted carbocyclic aromatic ring or substituted or unsubstituted heterocyclic aromatic ring; R ₃ : Hydrogen atom, substituted, unsubstituted amino group, substituted,
unsubstituted carbamoyl group, carboxyl group or ester group thereof; A': substituted or unsubstituted aryl group; n: an integer of 1 or 2; m: an integer of 0, 1 or 2. ] General formula [ ] [In the formula, _R7 and _R8 : substituted or unsubstituted phenyl group, _R9 : substituted or unsubstituted aryl group, heterocyclic group, _R10 to _R13 : hydrogen atom, halogen atom,
Represents an alkyl group, an alkoxy group, or an alkylamino group. ]