JPS6313179B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in electrophotographic photoreceptors. Conventionally, electrophotographic photoreceptors have been of the so-called dispersion type, in which a relatively large amount of an inorganic photoconductive substance such as zinc oxide, titanium oxide, or cadmium sulfide is coated on a conductive support in a suitable binder. so-called vapor-deposited types in which inorganic photoconductive substances such as selenium and selenium-based alloys are vapor-deposited, and poly-N-vinylcarbazole or its derivatives, polyphenylene pyrazole, polyvinylanthracene, polyvinylpyrene, oxazole, oxadiazole. , pyrazole or imidazole derivatives, anthracene, tetraphene, pyrene, and other organic photoconductive materials are known. However, dispersion type photoreceptors have the disadvantage of poor surface smoothness and mechanical strength due to the large amount of inorganic photoconductive material, while vapor deposition type photoreceptors are expensive to manufacture and have poor stability of the photoconductive material. Although organic photoreceptors are superior to dispersion and vapor deposition types in terms of flexibility and translucency, they generally have lower practical electrophotographic sensitivity. The drawback is that it is not yet widely available. In recent years, in order to improve these drawbacks, many so-called laminated type electrophotographic photoreceptors have been proposed. These can be broadly classified into three types. The first type is to provide a barrier layer mainly composed of metal oxide, polyamide, polyurethane, acrylic resin, polystyrene, etc. between the support and the photoconductive layer in order to suppress dark decay, or to prevent dark decay between the support and the photoconductive layer. In order to improve adhesion to the conductive layer, an adhesive layer mainly composed of polyamide, polyester, vinyl acetate resin, cellulose resin, polyvinyl alcohol, etc. is provided, or a protective layer such as cellulose resin or polyvinyl acetal is provided on the photoconductive layer. , silicone resin, polyester, vinyl chloride resin, vinyl acetate resin, polystyrene, acrylic resin, polyamide, etc. (the latter type can also be used for deformation processes other than the Carlson type, such as NP, PIP, and polarity reversal methods) ), and the second type is disclosed in Japanese Patent Publications No. 41-17187 and No. 42-23910.
No. 48-2965, an electrically insulating layer on a photoconductive layer containing polyethylene terephthalate, tetrafluoroethylene, cellulose acetate, polyvinyl alcohol, polyacrylonitrile, polyamide, polyvinylcarbazole, etc. as a main component. This type has a resin layer (this type is used only for complex deformation processes other than the Carlson process), and the third type is described in Japanese Patent Publications No. 43-16198, Japanese Patent Publication No. 45-5349, etc. As can be seen, a layer is provided on the photoconductive layer to move conduction carriers generated within the photoconductive layer by light absorption. However, although the first or second type improves mechanical strength and/or flexibility such as surface smoothness and adhesion to some extent, the electrophotographic sensitivity decreases, and the second type allows for more complex electrophotography. The third type has poor interlayer adhesion and is susceptible to charge barriers at the interface between the photoconductive layer and the conducting carrier layer, which makes it difficult to use after repeated use. Once deterioration of characteristics, fatigue phenomenon, residual potential, etc. occur, it becomes impossible to form a clear image. The present invention eliminates all of the above drawbacks and has the advantages of the first or second type, as well as
To provide an electrophotographic photoreceptor that is easy to manufacture despite being a laminated type, does not require a complicated electrophotographic process, and can form clear images. The present invention also provides a highly sensitive electrophotographic photoreceptor suitable for repeated use. That is, the present invention provides at least one charge carrier generating pigment represented by the following general formulas (1) to (4) on a conductive support, and an electron-accepting pigment represented by the following general formulas (5) to (10). The present invention is an electrophotographic photoreceptor in which a layer containing at least one substance and a layer containing at least one electron-donating substance represented by the following structural formulas (11) to (15) are sequentially laminated. general formula [In the formula, A is

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[Formula] or

[Formula] R ₀ represents -H, -C ₂ H ₄ , -C ₂ H ₄ Cl, or -C ₂ H ₄ OH. (Here, X is an aromatic ring such as a benzene ring or a naphthalene ring, an indole ring, a carbazole ring,
Ar 1 is a hetero ring such as a benzofuran ring or a substituted product thereof, Ar ₁ is a benzene ring, an aromatic ring such as a naphthalene ring, a hetero ring such as a dibenzofuran ring, or a substituted product thereof, Ar ₂ and Ar ₃ are a benzene ring, a naphthalene ring, etc. Aromatic rings or substituted products thereof, R ₁ and
R ₃ represents hydrogen, a lower alkyl group, a phenyl group, or a substitute thereof, and R ₂ represents a lower alkyl group, a carboxyl group, or an ester thereof. )] General formula (R ₁ to _{R 4} are H, NO ₂ , OCH ₃ , OC ₂ H ₅ , halogen, and at least one NO ₂ is included.) (R ₁ to _{R 3} represent H, NO ₂ and halogen.) Structural formula a first comprising a charge carrier generating pigment and an electron accepting substance;
In the layer, the weight ratio of the charge carrier generating pigment, which generates charge carriers by light absorption, and the electron accepting substance is suitably 1:10 to 1:0.001, preferably 1:2 to 1:0.5. be. Further, the first layer may contain a resin binder and a plasticizer as necessary. When a resin binder is used in the first layer, the amount of the resin binder and/or plasticizer is preferably 200% by weight or less, based on the total amount of the conductive carrier-forming substance and the electron-accepting substance.
Suitably, it is 100% by weight or less. Examples of resin binders include polyester, polycarbonate, polystyrene, polyvinyl methacrylate, polyvinyl acrylate, polyvinyl acetate, polyvinyl chloride, polyamide, polyurethane, silicone resin, alkyd resin, epoxy resin, cellulose resin, melamine resin, etc.
As the plasticizer, any plasticizer commonly used in the field of plastics can be used. The thickness of the first layer is 0.05~20μ, preferably 0.1~
A suitable value is 5μ. Next, a second layer containing the electron donating substance is placed on the first layer.
The layers are stacked. A resin binder and a plasticizer may also be used in the second layer. As the resin binder, any of the resins used in the first layer can be used, and as the plasticizer, those commonly used in the field of plastics can be used. Either can be used. The amount of resin binder and/or plasticizer in the second layer is 400% by weight or less, preferably 100% by weight, based on the electron donating material.
Suitably, it is less than or equal to % by weight. Furthermore, the thickness of the second layer is preferably 5 to 100 microns. The electrophotographic photoreceptor of the present invention is manufactured by a conventional coating method. That is, after applying a solution or dispersion of the material forming the first layer onto a conductive support such as a metal plate or metal laminated paper (or film), a solution or dispersion of the material forming the second layer is applied. do it. However, the solvent used for the solution or dispersion of the material forming the second layer is preferably one that dissolves the electron-accepting substance of the first layer. The photoreceptor of the present invention has the above-mentioned first layer and second layer as essential components, but within a range that does not impair the advantages of the present invention, conductive layers are added to improve the adhesion and charging characteristics of the photoreceptor. A resin layer of polyamide, vinyl acetate resin, polyurethane, polyester resin, acrylic resin, etc., or a thin layer of aluminum oxide or the like, with a thickness of about 0.01 to 1.0 μm, may be provided between the support and the first layer. The photoreceptor of the present invention configured as described above has a first
The layer contains a substance that generates conduction carriers by light absorption, and the reaction between the electron-accepting substance in the first layer and the electron-donating substance in the second layer results in the formation of a charge-transfer type complex at the interface of these layers. is formed, so
It is believed that the number of conductive carriers generated by light absorption increases and therefore the sensitivity is significantly improved. Although the details are not clear, the first and second layers
Since a charge-transfer type complex is formed at the interface with the layer, there is no barrier at the interface and the residual potential is reduced, making it possible to obtain clear images without background stains even after repeated use. It has been found that the layer structure of the present invention provides extremely good charge adhesion and retention and forms a high-density image. Examples are given below to specifically explain the present invention. In the text, all parts are by weight. Examples 1 to 35 One type of charge carrier generating pigment 1 shown in Table 1 selected from compounds represented by general formulas (1) to (4)
1 type of electron-accepting compound shown in Table 1 selected from compounds represented by general formulas (5) to (10)
After thoroughly mixing 0.5 parts of polycarbonate resin, 1 part of polycarbonate resin, and 100 parts of tetrahydrofuran in a ball mill, and applying the mixture using a doctor blade onto an aluminum-deposited polyester film to form a first layer with a dry film thickness of 1.5μ. , one electron-donating compound in Table 1 selected from compounds represented by structural formulas (11) to (15), and a polyester resin (manufactured by DuPont, trade name: Polyester Adhesive 49000) on the first layer. ) in 100 parts of tetrahydrofuran in the proportions shown in Table 1. Apply and dry the solution obtained.
A second layer having a thickness of 12 μm was formed to obtain a laminated electrophotographic photoreceptor. The obtained electrophotographic photoreceptor was subjected to corona discharge of -6.0KV for 20 seconds to charge the photoreceptor, and then left in a dark place for 20 seconds, and the surface potential Vpo at that time was
(volts) and then irradiated with 20 lux white tungsten light, the exposure amount E1/2 (lux seconds) required for Vpo to attenuate to 1/2 was measured. The results are shown in Table-1. Next, the latent image was charged and imagewise exposed using a known method, the latent image was developed dry or wet, and the toner image was electrostatically transferred and fixed on high-quality paper, resulting in a positive image faithful to the original image with no background stains. Examples 36 to 38 Electrophotographic photoreceptors were prepared in the same manner as in Examples 1 to 35, except that 1,2-dichloroethane was used in place of the tetrahydrofuran used in the first layer of Examples 1 to 35, and Vpo and E1/2 was measured. The results are shown in Table-2. Next, when a toner image was obtained on high-quality paper using the above photoreceptor in the same manner as in Examples 1 to 35, a positive image without background stains and faithful to the original image was obtained.

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Claims (1)

[Scope of Claims] 1 At least one charge carrier generating pigment represented by the following general formulas (1) to (4) and electrons represented by the following general formulas (5) to (10) on a conductive support. An electrophotographic photoreceptor comprising a layer containing at least one type of accepting substance and a layer containing at least one type of electron donating substance represented by the following structural formulas (11) to (15), which are sequentially laminated. general formula [In the formula, A is [Formula] [Formula] or [Formula] R ₀ represents -H, -C ₂ H ₅ , -C ₂ H ₄ Cl, or -C ₂ H ₄ OH. (Here, X is an aromatic ring such as a benzene ring, a naphthalene ring, a hetero ring such as an indole ring, a carbazole ring, a benzofuran ring, or a substituted product _thereof ; Heterocycles or their substituted substances, Ar ₂ and Ar ₃ are aromatic rings such as benzene rings and naphthalene rings, or their substituted substances, R ₁ and
R ₃ represents hydrogen, a lower alkyl group, a phenyl group, or a substituted product thereof, and R ₂ represents a lower alkyl group or an ester thereof. )] General formula (R ₁ to _{R 4} are H, NO ₂ , OCH ₃ , OC ₂ H ₅ , halogen, and at least one NO ₂ is included.) (R ₁ to _{R 3} represent H, NO ₂ and halogen.) Structural formula