JPH0347499B2 - - Google Patents

Description

[Detailed description of the invention]

1. Field of Industrial Application The present invention relates to a photoreceptor, such as an electrophotographic photoreceptor, having a photosensitive layer comprising a carrier generation phase and a carrier transport phase. 2. Prior Art According to conventionally known electrophotographic photoreceptors, a carrier generating material (hereinafter referred to as "CGM") that absorbs visible light and generates a charged carrier (hereinafter simply referred to as "carrier") is used. ) and a carrier transport material (hereinafter referred to as "CGL") that transports either or both of the positive and negative carriers generated in the CGL. A carrier transport layer (hereinafter referred to as "CTM") containing a
It is sometimes called "CTL". ) to form a photosensitive layer. in this way,
By assigning the two necessary basic functions of carrier generation and carrier transport to separate layers constituting the photosensitive layer, the range of materials that can be used in the composition of the photosensitive layer is widened, and each It becomes possible to independently select a material or material system that optimally performs the function. In addition, this provides various properties required in the electrophotographic process, such as high surface potential when charged, high charge retention capacity, high photosensitivity, and high stability during repeated use. It becomes possible to obtain an electrophotographic photoreceptor having the following properties. As the above-mentioned photosensitive layer, for example, the following ones are known. (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). Although many types of functionally separated photosensitive layers are known, in conventional electrophotographic photoreceptors having such photosensitive layers, the photosensitive layer changes when subjected to repeated electrophotographic processes. It has the disadvantage of severe electrical 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 particular carrier-generating substance is not necessarily effective against other carrier-generating substances. It cannot be said that a carrier generating substance that is effective against other carrier transport substances is also effective against other carrier transport substances.If the combination of both substances is inappropriate, not only will the electrophotographic sensitivity decrease, but especially Due to the poor discharge efficiency at low electric fields, the so-called residual potential becomes large, and in the worst case, the potential accumulates each time it is used repeatedly, making it practically unusable for electrophotographic purposes. In this way, it is thought that there is no lawful means of selecting a suitable combination of the constituent substances of the carrier generation phase and the constituent substances of the carrier transport phase, and an advantageous combination is determined practically from among many substance groups. There is a need to. 3. Purpose of the Invention The object of the present invention is to provide a photosensitive layer comprising a combination of a carrier generation phase and a carrier transport phase, which exhibits high sensitivity, and which maintains a high potential even when repeatedly used in an electrophotographic process, etc. It is an object of the present invention to provide a photoreceptor whose history state is maintained stably and which can always form good visible images. 4 Structure of the invention and its effects That is, the present invention provides a photoreceptor having a photosensitive layer consisting of a carrier generation phase and a carrier transport phase,
The present invention relates to a photoreceptor, wherein the carrier generation phase contains a tetraazo compound represented by the following general formula [], and the carrier transport phase contains a compound represented by the following general formula []. General formula []: A-N=N-Ar ¹ -N=N-Ar ² -N=N-Ar ³
-N=N-A [However, in this general formula, ^Ar1 and ^Ar2 : a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group, A:

【formula】

【formula】

【formula】

【formula】

【formula】

[expression] or

[Formula]. (X is hydroxy group,

[Formula] or -NHSO ₂ -R ⁶ [However, R ⁴ and R ⁵ are each a hydrogen atom or a substituted or unsubstituted alkyl group, and R ⁶ is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group] Y is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a carboxyl group, a sulfo group, a substituted or unsubstituted carbamoyl group, or a substituted or unsubstituted sulfamoyl group; Z is a substituted or unsubstituted sulfamoyl group; Atom group necessary to constitute a carbocyclic aromatic or heterocyclic aromatic ring, A′ is a substituted or unsubstituted aryl group, R ¹ is a hydrogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, An unsubstituted alkyl group, a substituted or unsubstituted carbamoyl group, a carboxyl group, or an ester group thereof, R ² and R ³ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aralkyl group aryl group, n is an integer of 1 or 2, m is an integer of 0, 1, 2, 3 or 4; )] General formula []: [However, in this general formula, R ⁷ : substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, R ⁸ : hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted aryl group, Q: hydrogen atom, halogen atom, alkyl group, substituted amino group, alkoxy group or cyano group; P: represents an integer of 0 or 1. ] In the present invention, the above-mentioned "phase" includes not only the case where the material forms a so-called layer, but also the case where the respective constituent materials form phases in contact with each other. According to the present invention, the tetraazo compound represented by the general formula [] is used as a CGM, and
By using the compound represented by the above general formula [] as CTM and skillfully combining them,
It constitutes the photosensitive layer of a so-called function-separated type photoreceptor in which carrier generation and transport are performed using separate substances, respectively. This makes it possible to provide a 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 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 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. 5 Examples Hereinafter, the present invention will be described in more detail with reference to Examples. First, the compounds of the general formulas [] and [] used in the present invention will be specifically illustrated. Specific examples of the tetraazo compound represented by the general formula [] include those having the following structural formula, but are not limited thereto. Specific examples of the hydrazone derivative represented by the general formula [] include those having the following structural formula, but are not limited thereto. Next, the present invention will be specifically explained with reference to the drawings. The photoreceptor of the present invention is constructed as shown in FIG. 1, for example. That is, a carrier generating layer 2 containing the above-mentioned tetraazo compound as a main component is formed on the conductive support 1, and a carrier containing the above-mentioned compound of the general formula [] as a main component is formed on this carrier-generating layer 2. The transport layer 3 is laminated, and the carrier generation layer 2 and the carrier transport layer 3 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. For example, as shown in FIG. 2, a conductive layer 1B is placed on an insulating substrate 1A.
The conductive support 1 can also be constructed by providing the following. In this case, the substrate 1A is paper,
A material having flexibility such as a plastic sheet and having sufficient strength against stress such as bending and tensile stress is suitable. Further, the conductive layer 1B can be provided by laminating metal sheets, vacuum-depositing metal, or by other methods. The carrier generation layer 2 is made of a tetraazo compound alone, a suitable binder resin is added thereto, or a substance having a high mobility for carriers of specific or non-specific polarity (i.e., a carrier transport substance) is added. It can be formed by Specific forming methods include a method in which the tetraazo compound is vacuum-deposited on the support, and a method in which the tetraazo compound is dissolved or dispersed in a suitable solvent alone or together with a suitable binder resin, and then applied and dried. can be mentioned. In this latter method, a binder resin or a carrier transport material may be added, and in this case, the ratio of carrier generating material: binder resin: carrier transport material is 1: by weight.
(0-100): (0-500), especially 1: (0-10):
(0.50) is preferred. Examples of the solvent or dispersion medium used in the above method 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 tetraazo 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. Furthermore, this carrier generation layer may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, and the like. Examples of electron-accepting substances that can be used here include succinic anhydride, maleic anhydride,
Dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride,
Tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, paranitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, brumanil, dichlorodicyanoparabenzoquinone , anthraquinone,
Dinitroanthraquinone, 2,7-dinitrofluorenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 9-fluorenylidene [dicyanomethylenemalonodinitrile], polynitro-9-fluorenylidene-[ dicyanomethylenemalonodinitrile],
Picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-
Examples include dinitrosalicylic acid, phthalic acid, mellitic acid, and other compounds with high electron affinity. In addition, the addition ratio of the electron-accepting substance is carrier generating substance: electron-accepting substance = weight ratio.
100:0.01-200 preferably 100:0.1-100. The thickness of the CGL 2 formed as described above is preferably 0.005 to 20 μm, particularly preferably
It is 0.05-5μm. If it is less than 0.005 μm, sufficient photosensitivity cannot be obtained, and if it exceeds 20 μm, sufficient charge retention cannot be obtained. Further, the CTL3 can be formed using the above-mentioned compound in the same manner as the above-mentioned CGL2 (that is, by coating the compound alone or dissolving and dispersing it together with the above-mentioned binder resin and drying). Further, other CTMs may be included. In this case, the blending ratio of the binder resin and the total carrier transport material is preferably 10 to 500 parts by weight per 100 parts by weight of the binder resin, and if polycarbonate is used as the binder resin, 100 parts by weight of the total carrier transport material is used. The use of 20 to 200 parts by weight of total carrier transport material is preferred as it provides excellent electrophotographic properties. Further, the above-mentioned electron-accepting substance may be added to this carrier transport layer for the purpose of improving sensitivity and further reducing residual potential or fatigue during repeated use. When this electron-accepting substance is added to both the carrier generation layer and the carrier transport layer, the electron-accepting substances added to each layer may be completely or partially the same, or in some cases, they may be completely different. I don't mind. Note that the electron-accepting substance may be added to either one of the carrier transport layers. The addition ratio of the electron-accepting substance to the carrier transport layer is such that the total carrier transport substance:electron-accepting substance is 100:0.01 to 100, preferably 100:0.1 to 50, by weight. The thickness of the carrier transport layer 3 thus formed is 2 to 100 μm, preferably 5 to 30 μm. As above, the present invention has been explained according to the specific structural example shown in FIG. 1 or FIG. This is sufficient, and the mechanical structure of the electrophotographic photoreceptor can be arbitrarily selected. For example, as shown in FIG.
A suitable intermediate layer 5 is provided thereon, a carrier generation layer 2 is formed thereon, and a carrier transport layer 3 is formed thereon.
may be formed. This intermediate layer 5 includes a photosensitive layer 4
It has a function of preventing free carriers from being injected from the conductive support 1 into the photosensitive layer 4 during charging, and a function as an adhesive layer that integrally adheres the photosensitive layer 4 to the conductive support. You can force it. 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. Further, as shown in FIG. 4, a carrier transport layer 3 is formed on the conductive support 1 with or without the intermediate layer 5, and a carrier generation layer 2 is formed thereon.
The photosensitive layer 4 may be formed by forming the following. Further, FIG. 5 shows a structure obtained by dispersing the above-mentioned carrier-generating substance (tetraazo compound) in a carrier-transporting phase containing the above-mentioned compound (that is, from a mixed layer of a carrier-generating substance phase and a carrier-transporting substance phase). An example in which a single-layer photosensitive layer is formed is shown below. Hereinafter, the present invention will be described in more detail with reference to specific examples. Example 1 On a conductive support made of polyethylene terephthalate with a thickness of 100 μm on which aluminum was vapor-deposited,
Vinyl chloride-vinyl acetate-maleic anhydride copolymer "Eslec MF-10" (manufactured by Sekisui Chemical Co., Ltd.)
An intermediate layer having a thickness of about 0.1 μm was provided. next,
2 g of the tetraazo compound shown by the structural formula (-5) already mentioned was added with 100 ml of 1,2-dichloroethane.
Dispersion was carried out using a ball mill for 12 hours, and the resulting dispersion was applied onto the intermediate layer using a doctor blade and sufficiently dried to form a CGL with a thickness of approximately 0.3 μm. On the other hand, compound 11.25 shown by structural formula (-2)
g and polycarbonate resin “Panlite L-
1250 (manufactured by Teijin Chemicals) in 100 ml of 1,2-dichloroethane, and the resulting solution was
It was applied onto CGL using a doctor blade and dried at a temperature of 80° C. for 1 hour to form CTL with a thickness of 12 μm, thus producing an electrophotographic photoreceptor according to the present invention. This will be referred to as "Sample 1". Examples 2 to 5 Completely the same as Example 1 except that each of those shown by structural formulas (-7), (-16), (-51), and (-64) was used as a tetraazo compound in the formation of CGL. Four types of electrophotographic photoreceptors according to the present invention were manufactured in the following manner. Each of these
"Sample 2", "Sample 3", "Sample 4" and "Sample 5"
shall be. Examples 6 to 8 In the formation of CTL, compounds according to the present invention were prepared in the same manner as in Example 1, except that compounds represented by structural formulas (-10), (-14), and (-30) were used as carrier transport substances. An electrophotographic photoreceptor was manufactured. These will be referred to as "Sample 6,""Sample7," and "Sample 8." Example 9 An intermediate layer was provided on a conductive support in the same manner as in Example 1, and 2 g of the tetraazo compound shown as exemplified compound (-5) and 1 g of polycarbonate resin "Panlite L-1250" were mixed at 1.2 g. - It was added to 100 ml of dichloroethane and dispersed in a ball mill for 12 hours, and the resulting dispersion was applied onto the intermediate layer using a doctor blade and sufficiently dried to form a CGL with a thickness of about 0.5 μm. A CTL was formed on this CGL in the same manner as the CTL in Example 1, thereby producing an electrophotographic photoreceptor according to the present invention. This is called “Sample 9”
shall be. Comparative Example 1 In the formation of CTL in Example 1, general formula []
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 instead of the compound represented by. This is referred to as "comparative sample 1." Comparative Example 2 In the formation of CTL in Example 1, general formula []
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 instead of the compound represented by. This will be referred to as "comparative sample 2." For each of the electrophotographic photoreceptors obtained as described above, Samples 1 to 9, Comparative Sample 1, and Comparative Sample 2, electrometer SP-428 type was used.
(manufactured by Kawaguchi Electric Seisakusho) to investigate its electrophotographic characteristics. In other words, the surface of the photoreceptor is charged with a potential of -
Acceptance potential V _A (V) when charged at 6KV for 5 seconds
and the potential after dark decay for 5 seconds (initial potential)
Exposure amount E1/2 required to attenuate V ₁ by 1/2
(lux・sec) was investigated. The results are shown in Table 1 below.

【table】

[Table] In addition, each of Samples 1 to 9, Comparative Sample 1, and Comparative Sample 2 was
2000R" (manufactured by Konishiroku Photo Industry Co., Ltd.) for continuous copying, and the black paper potential at an exposure aperture of 1.0.
Vb (V) and white paper potential Vw (V) were measured using an "Electrostatic Voltmeter Model 144D-ID" (manufactured by Monroe Electronics Inc.) immediately before development. The results are shown in Table 2 below. Note that 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 an original, and the white paper potential refers to the surface potential of the photoreceptor when a black paper with a reflection density of 1.3 is used as an original. Represents the surface potential of the body.

【table】

[Table] 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, and produces visible images with good image quality. can be stably formed in large numbers.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIGS. 1, 2, 3, 4, and 5 are sectional views of five examples of electrophotographic photoreceptors. In addition, in the symbols shown in the drawings, 1...substrate, 2...carrier generation layer (CGL), 3...carrier transport layer (CTL), and 4...photosensitive layer.

Claims (1)

[Scope of Claims] 1. A photoreceptor having a photosensitive layer consisting of a carrier generation phase and a carrier transport phase, wherein the carrier generation phase contains a tetraazo compound represented by the following general formula [], and the carrier transport phase contains a tetraazo compound represented by the following general formula []. A photoreceptor characterized by containing a compound represented by the general formula []. General formula []: A-N=N-Ar ¹ -N=N-Ar ² -N=N-Ar ³
-N=N-A [However, in this general formula, Ar ¹ , Ar ² and Ar ³ are each a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic aromatic ring group , A:
[Formula] [Formula] [Formula] [Formula] [Formula] [Formula] or [Formula]. (X is a hydroxy group, [Formula] or -NHSO ₂ -R ⁶ (However, R ⁴ and R ⁵ are each a hydrogen atom or a substituted or unsubstituted alkyl group, R ⁶ is a substituted or unsubstituted alkyl group, or Substituted or unsubstituted aryl group> Y is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a carboxyl group, a sulfo group, a substituted or unsubstituted carbamoyl group, or a substituted or unsubstituted sulfamoyl group, Z is an atomic group necessary to constitute a substituted or unsubstituted carbocyclic aromatic ring or a heterocyclic aromatic ring, A′ is a substituted or unsubstituted aryl group, R ¹ is a hydrogen atom, a substituted or an unsubstituted amino group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted carbamoyl group or a carboxyl group, or an ester group thereof; R ² and R ³ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted Substituted aralkyl group or substituted or unsubstituted aryl group, n represents an integer of 1 or 2, m represents an integer of 0, 1, 2, 3 or 4)] General formula []: [However, in this general formula, R ⁷ : substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, R ⁸ : hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted aryl group, Q: hydrogen atom, halogen atom, alkyl group, substituted amino group, alkoxy group or cyano group; P: represents an integer of 0 or 1. ]