JPS6335023B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite electrophotographic plate, and more particularly to a composite electrophotographic plate that uses a specific charge-generating substance and a charge-transporting substance, has excellent durability and repeatability, and is highly sensitive over an extremely wide spectral range. . A composite electrophotographic plate has a layer made of a charge-generating material and a charge-transporting material on a conductive support, and
This layer may be a homogeneous single layer containing both of the above materials or a multilayer structure consisting of a charge generating material layer and a charge transporting material layer. The charge generating material must have the ability to generate photocarriers by being exposed to light in the wavelength range used in electrophotographic plates, and to efficiently inject the photocarriers into the charge transporting material. Further, the charge transporting material must be transparent and non-absorbing to light in the wavelength range used in electrophotography, and must have the function of receiving and transporting the light carrier injected from the charge generating material. By using it, it is possible to improve the photoconductivity of the charge generating material and to physically protect the charge generating material, thereby forming a strong photosensitive plate. Hitherto, various compounds have been proposed as charge generating substances for such composite electrophotographic plates. That is, JP-A-52-55643 discloses monoazo dyes, disazo dyes, and squaric acid derivative dyes that are soluble in organic primary amines, and JP-A-53-42,830 and JP-A Showa 53-
No. 41230 discloses a quinocyanine pigment,
JP-A-51-11763 discloses copper phthalocyanine pigments. In addition to these many organic compounds, Japanese Patent Publication No. 15137/1983 discloses tellurium-arsenic-glassy selenium-based inorganic compounds, and Japanese Patent Publication No. 49-14272 discloses inorganic compounds containing imide bonds. Polymeric-amorphous selenium-based compounds are disclosed. Furthermore, the use of various compounds has been similarly proposed as a charge transporting substance for composite electrophotographic plates; for example, JP-A No. 52-77730 discloses trinitrothioxanthone; Publications and JP-A-52-75330 disclose polyvinylcarbazole or its derivatives, JP-A-49-105537 discloses pyrazoline derivatives, and JP-A-46-4484 discloses 2,4,7-trinitrofluorenone. In addition to 2,4,7-trinitrofluorenone, many other compounds (nitro and cyano substituted products) are disclosed in Japanese Patent Publication No. 301/1983. Composite electrophotographic plates made using the various compounds mentioned above as charge-generating substances or charge-transporting substances all have good electrophotographic properties, which are essential for the practical application of electrophotographic methods to copying devices, etc. It is inferior in durability and repeatability, which are important requirements, and
It has drawbacks such as being highly sensitive only to spectra in specific wavelength ranges, and these have been a major hindrance to commercialization. It is an object of the present invention to overcome the above-mentioned conventional drawbacks, to provide excellent durability and repeatability, high sensitivity over an extremely wide spectral range, and to be rigid or flexible so that it can be used on a wide range of substrates of many different shapes. It is an object of the present invention to provide a composite type electrophotographic plate that can be applied. To summarize the present invention, the composite electrophotographic plate of the present invention is a composite electrophotographic plate in which a layer consisting of a charge generating substance and a charge transporting substance is provided on a conductive support, and the charge generating substance contains antimony trisulfide. and the charge transport substance has the general formula [In the formula, X is a group

【formula】

【formula】

[Formula] and

[Formula] One type of heterocyclic group selected from the group consisting _{of 2} represents an alkyl group having 3 or less carbon atoms]. As described above, the charge generation material includes electrons and holes created by light passing through the charge transport material layer;
It is required that the generated holes must be injected into the charge transport material layer by means of an electric field. In addition, the charge transport material must be capable of effectively injecting optical carriers (charged bodies) generated in the charge generating material upon irradiation with light, and must have an appropriate absorption range that does not interfere with wavelengths absorbed by the charge generating material. It is extremely difficult to create materials that meet these requirements. There is a clear correlation between the effective injection of optical carriers and the ionization potential of charge generating and charge transporting materials. For example, when electrons are optical carriers, it is necessary that the charge transport substance has a higher ionization potential than that of the charge generating substance, and conversely, when holes are optical carriers,
Research results have been published that show that it is necessary to have a low level. However, in relation to these
No clear guidelines have been obtained for improving durability and repeatability, which are important for electrophotographic plates. As a result of various studies based on the above knowledge, the present inventors have found that a composite electrophotographic plate with excellent electrical properties can be obtained by using a material containing antimony trisulfide as a charge generating substance. This discovery led to the present invention. A particularly excellent advantage of the present invention is that by using the above-mentioned antimony trisulfide-containing material as a charge-generating substance together with a charge-transporting substance which is a compound represented by the above general formula, sensitivity is high over an extremely wide spectral range. The advantage is that electrophotographic plates can be obtained and can be applied on a wide variety of supports, rigid or flexible and of many different shapes. Antimony trisulfide in the present invention can be used alone, but it is also effective to form a charge-generating material layer by adding appropriate amounts of other substances such as tellurium, arsenic, and selenium. able to demonstrate. According to the study by the present inventors, as a charge transport substance, the general formula [In the formula, X is a group

【formula】

【formula】

[Formula] and

[Formula] One type of heterocyclic group selected from the group consisting of (however, Z represents O or S, and the heterocycle may be substituted), n is 0, 1 or 2, R ₁ and It has been confirmed that a composite electrophotographic plate having particularly excellent properties can be obtained by using a combination of compounds represented by the following formula: ₂ represents an alkyl group having 3 or less carbon atoms. In the compound represented by the above general formula in the present invention, the substituent of the heterocycle in the formula is -
Lower alkyl groups such as CH ₃ , -C ₂ H ₅ and -C ₃ H ₇ , -
Halogen groups such as Cl and -Br, -N( _CH3 ) ₂ , -N
dialkyamino groups such _as ( _C2H5 ) ₂ and -N _{( C3H7} ) ₂ ,
Examples include, but _are not limited to, alkoxy groups such as _-OCH3 and _-OC2H5 , and also phenyl groups. Representative examples of such compounds are listed below by structural formula. The method for synthesizing the above compound is described in Japanese Patent Publication No.
They are described in detail in Japanese Patent Publication No. 11218 and Japanese Patent Publication No. 35-11219, and most of them are commercially available as NK-dyes from Nippon Kanko Shiki Kenkyusho Co., Ltd. The reason why such a combination of a charge-generating substance and a charge-transporting substance exhibits good electrophotographic properties is not clear, but since high photosensitivity is exhibited especially when negatively charged, holes are more likely to be absorbed by the charge-transporting substance than by the charge-generating substance. Furthermore, the charge transporting substance of the present invention is relatively difficult to crystallize, is easy to blend with other polymer compounds, and is easy to obtain a strong and homogeneous coating film. Also, these substances have relatively low ionization potential values,
In particular, when holes are used as optical carriers, it is thought that this is due to the mutual effect of easy injection of optical carriers from the charge-generating substance. The charge generating material in the present invention can be used as a single layer mixed with a charge transporting material, or as a laminate in which each layer is a separate layer.
Further, the charge generating substance in the present invention can form a charge generating substance layer by itself, and vacuum deposition is suitable as a method for this purpose. On the other hand, the charge transport substance in the present invention can exert its effect by forming a charge transport substance layer by itself, but in order to improve the strength, flexibility, adhesion, etc. of the coating film, it is necessary to Systems mixed with molecular compounds can be used to increase effectiveness. The type of such polymer compound is not particularly limited, and may include known binder materials for electrophotographic plates, such as acrylic resin, butyral resin, polyester resin,
Polycarbonate resins, polyketone resins, polyurethane resins, and mixtures thereof can be used as appropriate. Further, the blending amount of these polymer compounds is 0.5 parts by weight of the charge transport material of the present invention.
A suitable range is 10 parts by weight. The thickness of the coating film of the charge-generating substance and the charge-transporting substance in the present invention is determined by the charging characteristics necessary for an electrophotographic plate, but it is suitably 100μ or less; has been confirmed to decrease. When used as a single layer, the thickness is usually about 5 to 100μ, and when used as a multilayer, the thickness of the charge generating material layer is usually about 0.1 to 5μ, and the thickness of the charge transporting material layer is about 5 to 100μ. is appropriate. In the case of forming a single layer, it is appropriate that the amount of the charge generating substance be about 10% by weight based on the amount of the charge transporting substance, but this amount can be selected as appropriate depending on the types of both substances. Brass, aluminum, gold, steel, etc. are used as the conductive support for the composite electrophotographic plate of the present invention, and these materials can be formed into sheet, thin plate, or cylindrical shape with appropriate thickness, hardness, or flexibility. It may be coated with a thin layer of plastic. It may also be metal coated paper, metal coated plastic sheet or glass coated with a thin layer of aluminum iodide, copper iodide or chromium oxide or tin oxide. It is generally desirable that the support be itself electrically conductive or have an electrically conductive surface and be strong enough to handle. Next, the present invention will be explained with reference to Examples, but the present invention is not limited to these in any way. Example 1 0.5 g of antimony trisulfide powder was placed in a molybdenum boat, and the substrate was 50 mm long, 50 mm wide, and 1 thick.
A charge-generating material layer was formed by vapor deposition using a vapor deposition apparatus manufactured by Shinko Co., Ltd. using an aluminum plate having a diameter of 1.0 mm and a distance between the boat and the substrate of 15 cm. in this case,
The heating conditions for molybdenum boats are 200℃ and 300℃.
℃, 400℃, 500℃ and 600℃ for 10 minutes each, and the substrate temperature was 200℃. The thickness of the obtained antimony trisulfide film was 1.5 μm. Next, the structural formula A mixed solution of 0.15 g of styryl dye (manufactured by Japan Photosensitive Color Research Institute, NK1347), 0.32 g of polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., Iupilon S2000), and 3 ml of dichloromethane and 1 ml of 1,2-dichloroethane were blended. A charge transport substance coating solution was prepared. In preparing the coating liquid, it was necessary to first completely dissolve the resin component and then add the charge transporting substance in order to obtain a homogeneous coating film. This coating liquid was applied onto the charge-generating material layer using an automatic applicator (manufactured by Toyo Seiki Co., Ltd.) and dried to form a film of the charge-transporting material with a thickness of about 10 μm. For the composite electrophotographic plate created in this way, an electrostatic recording paper tester (manufactured by Kawaguchi Electric Co., Ltd., SP-
As a result of electrophotographic characteristic evaluation using 428),
Half exposure sensitivity to white light when negatively charged (E ₅₀ )
showed a value of 10 lux·sec or less, which poses no problem for practical use. When the corona voltage is negative 5KV and the battery is charged in the dark for 10 seconds, the initial voltage V ₀ is approximately 500V, and the charge decay rate (V ₃₀ /
V ₀ ) is approximately 70%, which is a value that poses no problem in practical use, and when charging and exposure were repeated to examine changes in characteristics, even after 1000 repetitions, the initial voltage (V ₀ ) did not decrease by 10%. %, the decrease in dark decay rate was about 10%, and it was found that it could withstand more than 1000 repetitions. Example 2 In the same manner as in Example 1, the amount of antimony trisulfide in the molybdenum boat was changed to 0.2 μm, 1.0 μm,
Charge generating material layers having different thicknesses of 2.2 μm, 5.0 μm and 8.5 μm were formed. Next, the structural formula 0.3 g of oxazole derivative represented by
A mixed solution of 0.3 g of S200) and 3 ml of dichloromethane was prepared, and this coating solution was applied on the charge generating material layer in the same manner as in Example 1, and dried to a thickness of about 10 μm.
m charge transport material layers were formed. For these composite electrophotographic plates obtained, the half-decrease exposure sensitivity to white light when negatively charged was examined in the same manner as in Example 1. The results obtained are shown in Table 1.

[Table] As is clear from Table 1, as the thickness of the charge generating material layer increases, the sensitivity tends to decrease.
Best results are obtained with a film thickness of approximately 1 μm. Example 3 The same antimony trisulfide charge generating material layer as in Example 1 was formed. (Film thickness 1.4μm) Next, the structural formula A charge transport substance coating liquid was prepared by blending 0.3 g of the compound, 0.3 g of a saturated polyester resin (Pylon 200, manufactured by Toyobo Co., Ltd.), and a mixed solution of 2 ml of dichloromethane and 1 ml of 1,2-dichloroethane. This coating liquid was applied onto the charge generating material layer using an applicator and dried to form a charge transporting material layer. (Film thickness: 15 μm) The electrophotographic characteristics of the composite electrophotographic plate thus prepared were evaluated in the same manner as in Example 1, and the half-reduction exposure sensitivity to white light when negatively charged was 10 lux. Seconds or less, the repeatability is
It was good, more than 1000 times. Furthermore, using the same electrostatic recording paper testing device as in Example 1,
The spectral properties were measured. The results obtained are shown in Table 2.

[Table] As is clear from Table 2, it exhibits sufficient sensitivity to all colors and is particularly effective as a photoreceptor for copying machines. The blue, green, and red filters are Latsuchin Filter No. manufactured by Kodatsu.
47, No. 25 and No. 12 were used. Example 4 A charge generating material layer made of antimony trisulfide was formed in the same manner as in Example 1. (Film thickness: 1.5 μm) Next, 0.3 g of a charge transporting substance represented by the structural formula shown in Table 3, 0.3 g of acrylic resin (manufactured by Union Carbide, Elvacite 2045), 2 ml of dichloromethane, and 1 ml of 1,2-dichloroethane were added. A coating solution is prepared by blending the mixed solution, which is applied onto the charge generating material layer using an applicator, dried, and
A charge generating material layer was formed. (film thickness 15μm)

【table】

[Table] As shown in Table 3, the half-decrease exposure sensitivity (E ₅₀ ) to white light of the composite electrophotographic plates produced in this way was less than 10 lux·sec, which showed good characteristics. . As explained above, the composite electrophotographic plate of the present invention has excellent durability and good photosensitivity, and the sensitivity is high over an extremely wide spectral range, so its application fields are wide-ranging. For example, it can be effectively used in copying devices, printers, display elements, printing original plates, etc.

Claims (1)

[Scope of Claims] 1. A composite electrophotographic plate in which a layer consisting of a charge-generating substance and a charge-transporting substance is provided on a conductive support, wherein the charge-generating substance contains antimony trisulfide;
and the charge transport material has the general formula [wherein, ), n is 0, 1 or 2, and R ₁ and R ₂ represent an alkyl group having 3 or less carbon atoms. 2. The composite electrophotographic plate according to claim 1, wherein the charge generating material and the charge transporting material each form separate layers. 3. The composite electrophotographic plate according to claim 1, wherein the charge generating material and the charge transporting material form a single layer.