JPH0477907B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor suitably used in a laser beam printer using a semiconductor laser. [Prior art] Phthalocyanine compounds exhibit photoconductivity.
Since its discovery in 1968, a great deal of research has been conducted on it as a photoelectric conversion material. In recent years, with the development of non-impact printing technology, research has been actively conducted to develop laser beam printers that use semiconductor lasers as writing heads. In a laser beam printer used in electrophotography, a uniformly corona-charged photoreceptor is first irradiated with a laser beam modulated based on an input signal, and an image is formed by a toner phenomenon. It is believed that such a laser recording method improves the image quality, and in particular, the use of a semiconductor laser provides advantages such as simplifying the device, making it more compact, and making it possible to reduce the cost. Currently, most of the oscillation wavelengths of semiconductor lasers that operate stably are in the near-infrared region (λ>780nm). In other words, the recording photoreceptor used for it is 780n.
It is necessary to have high sensitivity in the wavelength range of m to 850 nm. In this case, the half-reduced exposure amount E1/2 of monochromatic infrared light irradiation required for practical sensitivity is 1 μJ/cm ² or less. Among photoconductive substances that exhibit high sensitivity in such long wavelength regions, phthalocyanine compounds are attracting particular attention. Conventionally, electrophotographic photoreceptors have been made of selenium, tellurium,
Inorganic compounds such as cadmium sulfide, zinc oxide,
Alternatively, organic compounds such as polyN-vinylcarbazole and bisazo pigments are used. However, these cannot be said to have sufficient photosensitivity in the long wavelength range of 780 nm to 900 nm, and in recent years, photoreceptors using an alloy of selenium, tellurium, and arsenic or photoreceptors using dye-sensitized cadmium sulfide have been developed.
It has been reported that they have high sensitivity in the long wavelength region around 800 nm, but all of them are highly toxic and their environmental safety is being reconsidered as a social issue. In addition, it is thought that it is possible to extend the photosensitive region of a photoreceptor using amorphous silicon to a long wavelength region by using a specific doping method and manufacturing method, but at present, the film formation rate is slow and there are problems with mass production, making it difficult to use. It's hard to say that it's a photoreceptor for the price. Among the phthalocyanine compounds that have been studied so far, x-type metal-free phthalocyanine compounds can be cited as compounds that are sensitive in the long wavelength region of 780 nm or more. However, a pigment-resin dispersion photoreceptor using an x-type metal-free phthalocyanine compound has relatively high sensitivity near 780 nm, but the sensitivity rapidly decreases in the long wavelength range of 800 nm or more, making it insufficient for practical use. . On the other hand, the characteristics of the pigment-resin dispersion photoreceptor are as follows:
At the initial stage of light irradiation, there is a phenomenon called the induction effect in which the light response is delayed, so the sensitivity tends to decrease significantly with light of a wavelength that is weakly absorbed. [Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor that exhibits relatively high sensitivity within the wavelength range of 780 to 900 nm. Another object of the present invention is to solve the problems of high dark decay and high residual potential that occur when electrophotographic photoreceptors are prepared by dispersing phthalocyanine pigments in a charge transporting medium such as poly-N-vinylcarbazole. The purpose of the present invention is to provide an electrophotographic photoreceptor. [Means for Solving the Problems] The present invention provides an electrophotographic photoreceptor having a photosensitive layer in which an x-type metal-free phthalocyanine compound is dispersed in a binder. material,
Furthermore, the above object has been achieved by an electrophotographic photoreceptor characterized by containing an electron transporting substance. Examples of the resin used as a binder in the present invention include resins generally used as binders for electrophotographic photoreceptors. Suitable examples are listed in Table 1.

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[Table] Suitable hole transport substances used in the present invention include, for example, quinoline compounds and derivatives thereof as shown in the general formula (), and indoline compounds and derivatives thereof as shown in the general formula ().
Specific examples are listed in Table 2.

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[Table] Examples of the electron transport substance used in the present invention include disazo pigments, perylene pigments, anzatron pigments, thiapyrylium salt derivatives, pyrylium derivatives, cyanine dye derivatives, and the like. Specific examples are shown in Table 3.

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〔Example〕

Example 1 Hole transport agent No.-13 10.0g "U Polymer" (manufactured by Unitika Co., Ltd.) 10.0g Dioxane 90.0g were completely dissolved, and then coated on an aluminum vapor-deposited mylar film and dried to form a 10 μm film. It was used as a charge transport layer. Next, x-type metal-free phthalocyanine 2.0g Disazo pigment No.P-13 0.5g Hole transport substance No.-13 10.0g Picric acid 0.02g "U polymer" (manufactured by Unitika Co., Ltd.) 10.0g Dioxane 90.0g A mixture of 60.0 g of glass beads (hard) was uniformly dispersed for 1.5 hours using a paint shaker, and then coated on the charge transport layer so that the film thickness of the photoreceptor was approximately 15 μm, dried, and a laminated type. A photoreceptor was created. "Paper Acalizer SP-428" (manufactured by Kawaguchi Electric Seisakusho Co., Ltd.) was used to measure the electrophotographic characteristics of the photoreceptor. The surface potential of the photoconductor immediately after each voltage of (+) 6kV and (-)6kV is applied to the surface of the photoconductor.
V ₀ (V) and the surface potential V ₁₀ (V) of the photoreceptor 10 seconds after stopping the voltage application were measured, and the charge retention ability of the photoreceptor was evaluated by the value of V ₁₀ /V ₀ . The sensitivity of the photoreceptor was measured by exposing the surface of the charged photoreceptor to light using a tungsten lamp as a white light source. The exposure amount required for the surface potential after exposure to decrease to 1/2 of the initial surface potential, assuming the exposure intensity is 5 lux.
E _1/2 (lux・sec) and the amount of exposure E _1/5 required for the surface potential after exposure to decrease to 1/5 of the initial surface potential.
(lux·sec) and the surface potential V ₁₅ (V) 15 seconds after the start of exposure were measured, and the sensitivity of the photoreceptor was evaluated based on these physical quantities. Comparative example 1 x-type metal-free phthalocyanine 2.0g Polyester "Vylon 200" (manufactured by Toyobo Co., Ltd.)
A mixture of 11.3 g of epichlorohydrin, 63.0 g of glass beads (hard), and 45.0 g of the mixture was uniformly dispersed in the same manner as in Example 1, and then spread onto an aluminum vapor-deposited mylar film provided with casein so that the film thickness was 15 μm. The coating was applied and dried to produce an electrophotographic photoreceptor. Comparative Example 2 Except for not adding disazo pigment P-13,
A photoreceptor having the same composition and structure as in Example 1 was produced. FIG. 7 shows the spectral sensitivities of the photoreceptors of Example 1 and Comparative Example 1. FIG. 8 shows optical attenuation characteristic curves of the photoreceptors of Example 1, Comparative Example 1, and Comparative Example 2. From FIG. 7, it can be seen that the photoreceptor of Example 1 shows no decrease in sensitivity in the long wavelength region of 800 nm or more. From FIG. 8, it can be seen that the residual potential is considerably reduced by adding the disazo pigment. Example 2 x-type metal-free phthalocyanine 2.0g Disazo pigment No.P-13 0.5g Hole transport agent No.-13 5.0g Picric acid 0.01g "U polymer" (manufactured by Unitika Co., Ltd.) 5.0g Dioxane 90.0g The mixture was uniformly dispersed in the same manner as in Example 1, and then coated on a casein-coated aluminum vapor-deposited Mylar film to a thickness of 3 μm and dried to form a charge generation layer. A solution of 5.0 g of hole transport agent No.-13 "U Polymer" (manufactured by Unitika Co., Ltd.) 5.0 g and 45.0 g of dioxane was applied on top of this to a film thickness of 12 μm and dried to form a charge transport layer. , a laminated photoreceptor was created. Example 3 A mixture of 2.0 g of x-type metal-free phthalocyanine, 0.5 g of disazo pigment No. P-13, 0.01 g of picric acid, 0.83 g of phenoxy resin "PKHH" (manufactured by Union Carbide), 30.0 g of chloroform, and 30.0 g of ethyl acetate was prepared in Example 1 above. After uniformly dispersing the mixture in the same manner as above, the mixture was coated and dried to a thickness of 0.5 μm on an aluminum vapor-deposited mylar film provided with casein to form a charge generation layer. On top of this, hole transport material No.-13 5.0g "U polymer" (Unitika
Co., Ltd.) and 45.0 g of dioxane was applied and dried to a film thickness of 12 μm to form a charge transport layer, and a laminated photoreceptor was prepared. Comparative Example 3 A mixture of 2.0 g of x-type metal-free phthalocyanine, 0.01 g of picric acid, 0.83 g of phenoxy resin "PKHH" (manufactured by Union Carbide), 30.0 g of chloroform, and 30.0 g of ethyl acetate was prepared in the same manner as in Example 1 above.
After uniformly dispersing the mixture, it was coated and dried to a thickness of 0.5 μm on an aluminum vapor-deposited mylar film provided with casein to form a charge generation layer. A charge transport layer similar to that in Example 3 was provided thereon to produce a laminated photoreceptor. The electrophotographic properties of the photoreceptors of Examples 2 and 3 and Comparative Example 3 are summarized in Table 4.

[Table] Furthermore, the spectral sensitivities of the photoreceptors of Examples 2 and 3 and Comparative Example 3 are shown in FIG. Examples 4 to 11 In the photoreceptor of Example 1, various combinations of hole transport materials and electron transport materials were used to create various photoreceptors. The characteristics of each are summarized in Table 5.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention has a photosensitive layer formed by dispersing an x-type metal-free phthalocyanine compound in a binder, and the photoreceptor contains a hole transporting substance and an electron transporting substance in the photosensitive layer. By this,
It has sufficient sensitivity in the long wavelength region of 780 to 900 nm, and also has a small residual potential. The electrophotographic photoreceptor of the present invention is not only excellent as a photoreceptor for laser beam printers that use a light source of about 750 to 900 nm, but also for various other recording devices that use a light source of 750 to 900 nm such as semiconductor lasers. It can also be applied to

[Brief explanation of drawings]

1 to 6 are enlarged partial cross-sectional views of an electrophotographic photoreceptor according to the present invention. 1... x-type metal-free phthalocyanine, 2... hole transport material, 3... electron transport material, 4... binder,
5... Charge-accepting substance, A... Conductive support, B
...Photosensitive layer, B-1...Charge transport layer, B-2...
Charge generation layer. FIG. 7 is a diagram showing the relative spectral sensitivities of the photoreceptor of Example 1 and the photoreceptor of Comparative Example 1. FIG. 8 shows the photoconductor of Example 1, the photoconductor of Comparative Example 1, and Comparative Example 2.
FIG. 3 is a diagram showing a light attenuation characteristic curve of a photoconductor. Figure 9
2 is a diagram showing the relative spectral sensitivities of the photoconductor of Example 2, the photoconductor of Example 3, and the photoconductor of Comparative Example 2. FIG.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer formed by dispersing an x-type metal-free phthalocyanine compound in a binder, the photosensitive layer containing a hole transporting substance and an electron transporting substance. An electrophotographic photoreceptor characterized by: 2 Hole transport material has general formula (In the formula, A ₁ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, and R ₁ , R ₂
and R ₃ each independently represent a hydrogen atom, a halogen atom, or an alkyl group, an aralkyl group, or an aryl group which may have a substituent. ) The electrophotographic photoreceptor according to claim 1. 3 The hole transport material has the general formula (In the formula, A ₂ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, and R ₄ and R ₅
each independently represents a hydrogen atom, a halogen atom, or an alkyl group, an aralkyl group, or an aryl group which may have a substituent. ) The electrophotographic photoreceptor according to claim 1. 4. Claim 1, wherein the electron transport substance is one or more compounds selected from the group consisting of disazo pigments, perylene pigments, anzanthrone pigments, thiapyrylium salt derivatives, pyrylium salt derivatives, and cyanine dye derivatives. 2. The electrophotographic photoreceptor according to item 2.