JPS6335022B2 - - 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 having excellent durability and repeatability using effective charge transport and charge generating materials. Conventionally, a composite electrophotographic plate is provided with a layer consisting of a charge generating substance and a charge transporting substance on a conductive support, and this layer is either a homogeneous single layer containing both of the above substances or a charge generating layer and a charge transporting substance layer. It has a multilayer structure consisting of The charge transport material must be transparent and non-absorbent to light in the special wavelength range used in electrophotography, and must have the ability to accept and transport electrons injected from the charge generation material. By using a charge transporting material, the photoconductive properties of the charge generating material can be improved, and the charge generating material can be physically protected to form a strong photosensitive plate. Regarding charge transporting substances having such an effect, the use of many compounds has been proposed, particularly in composite electrophotographic plates having a multilayer structure. That is,
JP-A-52-75328, JP-A-52-75329, and JP-A-52-75330 disclose the provision of a coating layer containing polyvinylcarbazole or a derivative thereof as a main component. The use of such an organic photoconductive insulator containing a carbazole vinyl polymer as a charge transporting material is also disclosed in Japanese Patent Publication No. 7811/1983. Also, Tokukai Akira
49-105537 and JP-A-52-72231 disclose the use of a triarylpyrazoline compound and a charge transporting substance with a binder added thereto, and JP-A-46-4484 discloses 2 , 4,7-trinitrofluorenone have been shown to be effective. In addition, the special public official 1973-
Publication No. 8221 and Japanese Patent Publication No. 53-301 disclose that in addition to the above-mentioned 2,4,7-trinitrofluorenone, many compounds are effective as charge transport substances, and that charge generation occurs in binders containing these compounds. The structure and effects of a single-layer type electrophotographic plate in which a substance is dispersed and a multi-layer type electrophotographic plate in which both layers are provided as separate layers are disclosed in detail. All of the above-mentioned compounds have good charge transport properties, but they are inferior in durability and repeatability, which are essential requirements for practical use of electrophotographic methods in copying machines, etc., and this makes it difficult to commercialize them. It was a hindrance. The purpose of the present invention is to eliminate the drawbacks of electrophotographic plates containing the above-mentioned conventional materials, and to provide a specific charge transport material and a charge transport material that have excellent durability and repeatability, and have charge transport characteristics as good as or better than those of the conventional materials. It is an object of the present invention to provide a composite electrophotographic plate that uses a generating substance. 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, wherein the charge transporting substance has the general formula -(CH=CH) _o -CH=Y [wherein, X is a group

【formula】

【formula】

[Formula] and

One type selected from the group consisting of [Formula] heterocyclic group, Y is

【formula】

【formula】

[Formula] and

One type of heterocyclic group selected from the group consisting of [Formula] (where Z represents O, S or Se,
R represents an alkyl group, the heterocycle may be further substituted), n represents 1 or 2,
In addition, it consists of a compound represented by -(CH=CH) _o - one of the hydrogen atoms of the group may be substituted],
It is characterized in that the charge generating substance is comprised of an organic pigment selected from the group consisting of a disazo pigment, a methine squaritcate pigment, and a copper phthalocyanine pigment. As mentioned above, the charge transport substance must be able to effectively inject optical carriers (charged bodies) generated into the charge generating substance by light irradiation, and block the special wavelength (4200 to 8000 Å) absorbed by the charge generating substance. It is extremely difficult to create a material that meets both of these requirements, such as having an appropriate absorption range that does not interfere with the charge transfer and having excellent charge transport properties. As is well known, a charge-generating material photogenerates pairs of electrons and holes when irradiated with light, and these are injected and transported into a charge-transporting material as photocarriers. There is a clear correlation between the injection and the ionization potential of the charge transport material; when electrons are used as optical carriers, the ionization potential is high, and when holes are used as optical carriers, the ionization potential is high. Research has been published showing that the potential is low. However, in relation to these, clear guidelines have not yet been obtained for improving durability and repeatability, which are important for electrophotographic plates. As a result of various studies based on the above-mentioned known knowledge, the present inventors have discovered that a compound represented by the above general formula (hereinafter referred to as the compound of the present invention) can be used in a composite electrophotographic plate using the above-mentioned organic pigment as a charge-generating substance. ) has been found to exhibit excellent properties as a charge transport material, and the present invention has been arrived at. In the compound of the present invention, one of the hydrogen atoms of the heterocyclic group and the -(CH=CH) _o - group may be further substituted with various substituents. Examples of such substituents include -CH ₃ ,
−C ₂ H ₅ , −C ₃ H ₇ , −Cl, −Br, −N(CH ₃ ) ₂ , −N
Examples include (C ₂ H ₅ ) ₂ , -OCH ₃ and -C ₆ H ₅ , but are not limited to these. Such compounds are listed below by structural formula. The general synthesis method for the above compounds is LGS
Brooker et al., Journal of American
Chemical Society. Vol. 62, P. 1116 (1940), etc., and some of these compounds are commercially available as NK-dyes from Japan Photosensitive Color Research Institute. The reason why the compounds of the present invention are excellent as charge transport materials is not clear, but it is because these materials are relatively difficult to crystallize, are easy to blend with other polymer compounds, are strong, and It is easy to obtain a homogeneous coating film, and this material has a relatively low ionization potential value, so that it is easy to inject photocarriers from the charge-generating material, especially when holes are used as photocarriers. This is thought to be due to a surplus effect. The compounds of the present invention can be used in the form of a single layer mixed with a charge-generating substance, or in the form of a multilayer, each layer being a separate layer. In addition, the compound of the present invention can exert its effect by forming a charge transport layer by itself, but in order to improve the strength, flexibility, adhesion, etc. of the coating film, it may be mixed with other polymer compounds. The effect can be increased by using a system with 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 resin, polyketone resin, polyurethane resin, etc. can be used as appropriate.
The amount of these polymer compounds to be blended is suitably within the range of 0.5 to 10 parts by weight per 1 part by weight of the compound of the present invention. 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 generation layer is usually about 0.1 to 5μ, and the thickness of the charge transport layer is about 5 to 100μ. It is. 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 sufficiently strong 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 Structural formula The chlorinated Diane Blue represented by is mixed with ethylenediamine and n-butylamine in a 1:1 (volume ratio)
A solution dissolved in a mixed solvent to a concentration of 1% by weight was applied onto an aluminum plate with a thickness of 100 μm using an applicator and dried to form a film of the charge generating material with a thickness of about 1 μm. Next, the structural formula The compound shown by (manufactured by Japan Photosensitive Color Research Institute, NK
-2321) and polycarbonate resin (Iupilon S2000, manufactured by Mitsubishi Gas Chemical Co., Ltd.) at a weight ratio of 1:2, a 16% by weight solvent was prepared using dichloromethane as a solvent, and this solution was applied onto the film of the above charge generating material. It was applied with an applicator and dried to form a coating of charge transport material approximately 30 microns thick. For the composite electrophotographic plate produced in this way, an electrostatic recording paper tester (SP-
As a result of electrophotographic characteristic evaluation using 428),
The half-decrease exposure sensitivity to white light during charging was less than 10 lux·sec, a value that poses no problem for practical use. Furthermore, when repeated characteristic evaluations were performed using the same apparatus, no tendency for electrophotographic characteristics to deteriorate, including half-reduction exposure sensitivity, was observed even after repetitions were repeated 10 ³ times or more. Example 2 Structural formula A composite electrophotographic plate was prepared in the same manner as in Example 1, except that the compound represented by was used as the charge transport material. As a result of conducting the same test as in Example 1, the half-reduced exposure sensitivity was 10 lux/second or less and 10 ³
The property of being repeatable over many times was demonstrated. Example 3 Structural formula A 1:2 weight ratio of methine squaritcate dye and butyral resin (manufactured by Union Carbide, XYHL) was prepared, a 1% by weight solution was prepared using tetrahydrofuran as a solvent, and the mixture was kneaded in a ball mill to form a coating solution. This coating liquid was applied onto an aluminum plate using an applicator and dried to form a film of the charge generating material with a thickness of about 0.5 μm. Next, as a charge transport material, 4 shown in Table 1 below is used.
Compounds of types [(3) to (6)] and acrylic resin (manufactured by Dupont, Elvacite 2045) were blended at a weight ratio of 1:5, and a mixed solvent of dichloromethane and benzene (volume ratio) of 1:1 was added. In addition, a 10% by weight solution was prepared and mixed in a ball mill, and a coating solution was applied onto the charge-generating material coating and dried to form a charge-transporting material coating with a thickness of approximately 20 μm. The composite electrophotographic plate thus prepared was subjected to the same tests as in Example 1 to examine its half-decrease exposure sensitivity and repetition characteristics. The results obtained are shown in Table 1 below.

[Table] As is clear from Table 1, all of them exhibited good half-decrease exposure sensitivity of 20 lux·sec or less and repeatability of 10 ³ times or more. Comparative Example 1 A composite electrophotographic plate was prepared in the same manner as in Example 3, except that the compounds shown in Table 2 below were used as charge transport materials. The results obtained by conducting the same test as in Example 1 are shown in Table 2 below.

[Table] As is clear from Table 2, the half-decrease exposure sensitivity is inferior to the case where the charge transport substance of the present invention is used. Example 4 1 part by weight of copper phthalocyanine pigment (Lionol ESP, manufactured by Toyo Ink Co., Ltd.) was used as a charge generating substance, and three types shown in Table 3 below as charge transporting substances [(7)~
(9)] and polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., Iupilon)
S2000) was mixed to prepare a 15% by weight solution using dichloromethane as a solvent and kneaded in a ball mill to prepare a coating solution consisting of a mixture of a charge generating substance and a charge transporting substance. This coating liquid was applied onto an aluminum plate and dried to produce a composite electrophotographic plate.
The thickness of the coating film was approximately 50μ. The results obtained by conducting the same test as in Example 1 are shown in Table 3 below.

【table】

[Table] As is clear from Table 3, all of them exhibited good half-reduction exposure sensitivity of 30 lux/second or less and repeatability of 10 ³ times or more. Comparative Example 2 A composite electrophotographic plate was prepared in the same manner as in Example 4, except that the compounds shown in Table 4 below were used as charge transporting substances. The results obtained by conducting the same test as in Example 1 are shown in Table 4 below.

[Table] As is clear from Table 4, the half-decrease exposure sensitivity is inferior to that in the case where the charge transporting substance of the present invention is used. Example 5 A composite electrophotographic plate was prepared in the same manner as in Example 1, except that the compounds shown in Table 5 below were used as the charge transport material. The results obtained by conducting the same test as in Example 1 are shown in Table 5 below.

【table】

[Table] As is clear from Table 5, all of them exhibited good half-decrease exposure sensitivity of 30 lux·sec or less and repeatability of 10 ³ times or more. As described above, the composite electrophotographic plate of the present invention has excellent durability (half-decrease exposure sensitivity) and repeatability, and can be used in a wide range of fields, such as copying machines, printers, display elements, and printing original plates. It can be effectively applied to, etc.

Claims (1)

[Claims] 1. In 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, the charge transporting substance has the general formula X-(CH=CH) _o -CH= Y [wherein, X is a heterocyclic group selected from the group consisting of [formula] [formula] [formula] and [formula]; One type of heterocyclic group selected from the group consisting of (where Z represents O, S or Se,
R represents an alkyl group, the heterocycle may be further substituted), n represents 1 or 2,
Furthermore, one of the hydrogen atoms of the -(CH=CH) _o - group may be substituted. A composite electrophotographic plate characterized by comprising an organic pigment selected from. 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.