JPS6255653B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic plate that is effective for creating images by electrophotography, and more particularly to a composite type electrophotographic plate composed of a charge-generating substance and a charge-transporting substance that are highly sensitive even to long-wavelength light. . Conventionally, charge generating substances for composite electrophotographic plates include monoazo dyes, disazo dyes, and squaric acid derivative dyes soluble in organic primary amines as shown in JP-A No. 52-55643, and squaric acid derivative dyes as shown in JP-A-52-55643. −
Many organic substances have been proposed, such as the quinocyanine pigment shown in No. 42830 and JP-A-53-41230, and the copper phthalocyanine pigment shown in JP-A-51-117637. On the other hand, inorganic materials such as tellurium-arsenic-vitreous selenium-based materials as shown in Japanese Patent Publication No. 15137-1982 and polymers having imide bonds and amorphous selenium-based materials as shown in Japanese Patent Publication No. 49-14272 have also been proposed. Furthermore, as charge transport substances, polyvinylcarbazole-based materials shown in JP-A-52-77730 and JP-A-52-753929, pyrazoline derivatives shown in JP-A-49-105537, JP-A-46- No. 4484, Japanese Patent Publication No. 1983-
Trinitrofluorenone shown in No. 10738, various nitro- and cyano-substituted compounds shown in Japanese Patent Publication No. 53-301, etc. are proposed. Electrophotographic plates using these materials all have good electrophotographic properties, but they all use visible light (wavelengths from 400 to 400).
700nm) and has high sensitivity to near-infrared light (wavelength 750nm).
The disadvantage is that there is almost no sensitivity to the above), and even if there is sensitivity, the sensitivity is low. In recent years, as a type of high-speed printer, a printing method using an electrophotographic method using a laser as a light source has been devised. It is desired to develop an electrophotographic plate that has high sensitivity to a specific wavelength, although it varies depending on the laser used as a light source. In particular, when a semiconductor laser is used as a light source, the light source section is extremely small, making it possible to miniaturize the printer and significantly reduce power consumption.
Attention has been paid. However, the oscillation wavelength of a semiconductor laser is usually an extremely long wavelength of 800 nm or more. Therefore, there has been a strong desire to develop an electrophotographic plate that is sensitive to wavelengths of 800 nm or more. Conventional electrophotographic plates such as those mentioned above are mainly used in copiers that use white light as the light source;
It has the highest sensitivity for wavelengths of 600 nm or less, and has no sensitivity at all for wavelengths of 800 nm or more, or even if it does have sensitivity, it is too low to be of practical use. If the sensitivity is high, high-speed printing is possible and the output of the light source can be reduced. The purpose of the present invention is to overcome the drawbacks of conventional electrophotographic plates, to have high sensitivity over an extremely wide wavelength range (500 to 825 nm), and to have excellent durability, repeatability, rigidity or flexibility, and a large number of different shapes. The purpose of the present invention is to present a composite electrophotographic plate suitable for use on a wide variety of substrates. As a charge-generating material, it is required that light passing through the charge transport layer forms electrons and holes, and the generated holes (or electrons) must be injected into the charge transport layer using an electric field. . In addition, the charge transport substance must meet various conditions, such as being able to effectively inject optical carriers generated in the charge generating substance by light irradiation, and having an appropriate absorption range that does not interfere with the wavelengths absorbed by the charge generating substance.
Creating good materials is extremely difficult.
There is a clear correlation between the effective injection of the optical carrier and the ionization potential of the charge transport material. For example, research results have been published that show that when electrons are carriers, the ionization potential of a charge transporting substance needs to be higher than that of a charge generating substance, and conversely, when holes are carriers, it needs to be lower. The existing charge-generating materials and charge-transporting materials described above cannot provide good characteristics simply by using them in combination. Although it is possible to obtain certain characteristics as an electrophotographic plate by simply combining them, it is difficult to put them into practical use. For example, when a β-type copper phthalocyanine pigment is used as a charge-generating substance and a pyrazoline derivative is used as a charge-transporting substance, a sensitivity value that can be used practically can be obtained, but the initial potential and dark decay are poor and it cannot be used practically. At present, no clear reason has yet been found regarding the compatibility of the combination of a charge-generating substance and a charge-transporting substance. The present inventors, based on the above-mentioned known facts,
As a result of various studies, an extremely suitable combination of a charge generating substance and a charge transporting substance as shown in the present invention was discovered. The composite electrophotographic plate of the present invention is characterized in that a charge generation layer and an electron transfer type charge transport layer are provided in this order on a conductive support. The charge transport layer is composed of a mixture of a copper phthalocyanine pigment and a disazo pigment represented by the following general formula (D), and the charge transport layer is composed of a 9-(p-vinylphenyl) polycyclic aromatic vinyl polymer represented by the following general formula (A). Anthracene polymer, 9-(p-
At least one selected from copolymers of vinylphenyl)anthracene monomers and other vinyl monomers and brominated 9-(p-vinylphenyl)anthracene polymers; and at least one nitrofluorenone represented by the following general formula (B). A composite type electrophotographic plate for positive charging characterized by being made of a mixture of However, X represents _-OCH3 , Cl group. However, m and n are integers and 1≦(m+n)≦3, and the amount of the anthracene polymer and nitrofluorenone in the charge transport layer is 0.1 to 3 parts by weight of the nitrofluorenone per 1 part by weight of the anthracene polymer. Preferably, the range is within the range. Further, the thickness of the charge transport layer is preferably in the range of 5 to 30 μm, and the thickness of the charge transport layer is preferably in the range of 0.5 to 5 μm.
Such fluorenones include 2-nitrofluorenone, 2,4-dinitrofluorenone, 2,
Examples include 5-dinitrofluorenone, 2,7-dinitrofluorenone, 2,4,5-trinitrofluorenone, and 2,4,7-trinitrofluorenone. At least one of these is mixed with the anthracene polymer to form a charge transport material. On the other hand, suitable charge generating substances for the above charge transporting substance include copper phthalocyanine pigments and the following general formula:
Examples include a mixture of disazo pigments represented by (D). However, X represents _-OCH3 , cl group. When these charge generation layers and charge transport layers are used in combination, an electrophotographic plate with extremely high sensitivity can be obtained. As a method for producing a composite type electrophotographic plate in the present invention, it is preferable to form a charge generation layer on a conductive support and then form a charge transport material. A method of using a mixture of two or more types of charge generating substances is disclosed in JP-A-50-75042. This document describes a method for creating a photoreceptor with a wide sensitive wavelength range by using at least two types of pigments or dyes that absorb at relatively long and short wavelengths in different spectral regions. The charge-generating substances shown here include a phthalocyanine pigment to increase photosensitivity in the red spectral region (long wavelength side), a perylene pigment to increase photosensitivity in the blue spectral region (short wavelength side), There are quinacridone pigments, polynuclear quinone pigments, thioindigo pigments, and the like, and it is said that by using two substances with different regions in combination, a photoreceptor with a wide photosensitive wavelength range can be obtained. On the other hand, poly-9- used as a charge transport material
A photoconductor based on (p-vinylphenyl)-anthracene and nitrofluorenone is disclosed in Japanese Patent Publication No. 43893/1983. According to this, high sensitivity with a half-reduced exposure sensitivity of 7 lx・s can be obtained without using a charge-generating substance such as a copper phthalocyanine pigment, but the wavelength range in which this photosensitivity occurs is within the range of 400 to 700 nm.
It is stated that there is no sensitivity to light with a wavelength of 700 nm or more. Thus, the poly-9-(p-vinylphenyl)-anthracene to nitrofluorenone photoconductor, which has no sensitivity to wavelengths of 700 nm or more, can be combined with a copper phthalocyanine pigment to achieve extremely high sensitivity. , is an unexpected phenomenon. It is well known that copper phthalocyanine pigments themselves have a certain degree of sensitivity to long wavelengths. It is thought that this unique phenomenon occurs because the copper phthalocyanine pigment is significantly sensitized by poly-9-(p-vinylphenyl)-anthracene, and as mentioned above, the charge-generating substance and charge-transporting substance It is speculated that this is due to compatibility, but details such as the sensitization mechanism are still unknown. Note that a charge transfer layer mainly composed of a charge transfer complex formed from an electron donating substance such as poly-9-(p-vinylphenyl)-anthracene and an electron accepting substance such as nitrofluorenone shown in the present invention may be used. A laminated electrophotographic photoreceptor having the above structure is disclosed, for example, in JP-A-54-10738. According to this, the electron-donating substances used in the charge transfer layer include polymers having polynuclear aromatic hydrocarbons as repeating units, such as poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinyl Phenylanthracene, poly-9-vinylanthracene, polyacenaphthalene, poly-9-(4-
pentenyl) carbazole, poly-9-(5-hexyl) carbazole, polymethylene pyrene,
Poly-1-(pyrenine)butadiene or N-substituted acrylic acid amide polymers of pyrene and alkyl, nitro, amino, halogen or hydroxy substituted products of these polymers are mentioned. Also N-
Copolymers of vinyl carbazole and methyl acrylate, block copolymers of 1-vinylpyrene and formaldehyde can also be used, and monomers other than the above polymers such as carbazole, N-ethylcarbazole, pyrene, Tetraphene, 1-acetylpyrene, 2,3-benzochrysene, 6,7-benzopyrene, 1-bromopyrene, 1-ethylpyrene, 1-methylpyrene, perylene, 2-phenylindole, tetracene,
Picene, 1,3,6,8-tetraphenylpyrene, chrysene, fluorene, phenanthrene,
2,3-benzopyrene, anthraquinone, dibenzothiophene, naphthalene and 1-phenylnaphthalene, tris(dialkylaminophenyl)
Methane leuco, bis(dialkylaminophenyl)methane, bis(dialkylaminophenyl)
Examples include ether, 2,5-bis(dialkylaminophenyl)-1,3,5-oxadiazole, and pyrazoline derivatives. On the other hand, examples of electron-accepting substances include phthalic anhydride, tetrachlorophthalic anhydride, mellitic anhydride, pyromellitic anhydride, tricyanobenzene,
Picryl chloride, 2,4-dinitrochlorobenzene, 2,4-dinitrobromobenzene, 4-nitrophenyl, 4,4-dinitrobiphenyl, 2,
4,6-trinitroanisole, trichlorotrinitrobenzene, trinitro-0-toluene,
4,6-dichloro-1,3-dinitrobenzene,
4,6-dibromo-1,3-dinitobenzene, p
- dinitrobenzene, chloranil, chromal,
2,4,5-7-tetranitrofluorenone,
2,7-dinitrofluorenone, tetracyanoquinodimethane, tetracyanoethylene, trinitroanthracene, dinitroacridine, tetracyanopyrene, dinitroanthraquinone, 2 (or 4)-aza-9-fluorenone, 9-dicyanomethylenefluorenone, 9 -dicyanomethylene-
2,4,7-trinitrofluorenone, 2,4,
6-trinitrostilbene, tetracyanoethylene, 2,4,7-trinitro-9-fluorenylidenemalonodinitrile, 4,9-dinitrobenzotrobone, etc., nitro group, carboxyl group, cyano group with strong electron-withdrawing properties Compounds having substituents such as As a result of various studies, the present inventors found that poly-9-(p-vinylphenyl)-anthracene, 9
Copolymers of -(p-vinylphenyl)-anthracene monomers and other vinyl monomers and poly-9-
An electrophotographic plate in which a mixture of at least one selected from (p-vinylphenyl)-anthracene bromide and at least one nitrofluorenone is used as a charge transporting substance and a copper phthalocyanine pigment is used as a charge generating substance is specifically provided. I found it to be excellent. The electrophotographic plate of the present invention has a characteristic of exhibiting high sensitivity particularly to long wavelengths of 750 nm or more, and further has sufficient flexibility, which is essential for commercialization. For example, the well-known poly-N-
When vinylcarbazole and 2,4,7-trinitrofluorenone are used as a charge transporting substance, the flexibility of the charge transporting substance layer is significantly reduced in order to achieve a sensitivity that can be used as an electrophotographic plate.
Not for practical use. For this purpose, a third
It has the disadvantage that it requires the addition of substances. In addition, for long wavelengths (750 nm or more), poly-9-(vinylphenyl)-
Electrophotographic plates using poly-N-vinylcarbazole to 2,4,7-trinitrofluorenone as charge transport materials have lower sensitivity than those using anthracenes to nitrofluorenone as charge transport materials. The reason for this is unknown in detail, but
When the former poly-9-(p-vinylphenyl)-anthracene to nitrofluorenone is used as a charge transporting substance and is formed on a charge generating substance layer, the sensitivity is significantly higher only when positively charged than when negatively charged. However, the latter poly-N-vinylcarbazole~2,
When 4,7-trinitrofluorenone is used as a charge transporting substance and is formed on a charge generating substance layer, it exhibits almost the same sensitivity when charged negatively and when charged positively, which suggests that the photosensitive mechanisms of the two are different. Ru. The copper phthalocyanine pigment used as a charge generating substance in the present invention has α, β, γ,
Although they are classified into ε, X-type, etc., any of their crystal forms can be used, and it is more preferable to use a mixture of monoazo and disazo pigments. When a mixture of pigments is used, not only does the sensitive wavelength range become wider, but the photosensitivity in the long wavelength red spectral region is improved by about 1.5 to 2 times compared to when the charge generating substance is used alone. We discovered this unique phenomenon and arrived at the present invention. Photosensitivity cannot be improved simply by increasing the thickness of the charge-generating substance. Although the details of the reason for this improvement in photosensitivity are unknown, the two pigments have good compatibility and can form a uniform charge generation layer, which improves the generation of light carriers during exposure. It can be inferred that. Regarding the blending ratio of the mixture of charge generating substances, if the amount of the copper phthalocyanine pigment increases, the sensitivity will improve in the long wavelength side of the spectrum, but on the other hand, the dark decay will deteriorate, so monoazo lake pigment or disazo pigment 1 will be used. For parts by weight,
Particularly preferred is a range of 0.1 to 10 parts by weight of copper phthalocyanine. The method for forming the charge generating material layer is as follows:
The substance is added with an organic solvent and, if necessary, a polymer compound (binder for electrophotography), etc., and milled into fine particles (particle size of 5 μm or less, especially 1 μm) using a ball mill or roll mill.
After pulverizing the charge-generating substance into particles (μm or less) to prepare a charge-generating substance coating liquid, a charge-generating layer is formed on the conductive support using a coating machine or the like. The mixing ratio of the anthracene polymer and nitrofluorenone as charge transporting substances is particularly preferably in the range of 0.1 to 3 parts by weight of the nitrofluorenone per 1 part by weight of the anthracene polymer. As a method for forming a layer of a charge transporting substance, the substance is dissolved in an organic solvent, and the charge transporting layer is formed by coating in the same manner as the charge generation layer. A polymer compound or the like is added to the charge transport layer as necessary. In this case, it is preferable to first dissolve the polymer compound in an organic solvent and then dissolve the charge transport substance. The polymer compounds used in each of these layers include known binders for electrophotography, such as polycarbonate resins, acrylic resins, polyester resins,
At least one of butyral resin, polyketone, polyurethane resin, etc. can be used as appropriate. In the present invention, when the charge generating substance and the charge transporting substance are separated into a charge generating layer and a charge transporting layer, respectively, the thickness of the charge generating layer is determined depending on the required photosensitivity and the relationship between the charge generating substance and the polymer compound. It is determined by the blending ratio of 20 μm or less, especially 0.5 to 5 μm
The range of m is preferable; if it exceeds this range, not only the photosensitivity will decrease, but also the flexibility of the film will be lost and peeling will occur. In addition, the blending amount of the charge-generating substance and the polymeric compound resin binder is preferably 4 parts by weight or less of the polymer compound per 1 part by weight of the charge-generating substance; if it exceeds this, the photosensitivity tends to gradually decrease. . On the other hand, the thickness of the charge transport layer is determined by the charging characteristics required for an electrophotographic plate, but the thickness is
A suitable thickness is 100 μm, preferably 5 to 30 μm. Further, the blending amount of the charge transporting substance and the polymer compound resin binder is preferably 10 parts by weight or less, particularly within the range of 0 to 3 parts by weight, per 1 part by weight of the charge transporting substance. It is. By laminating these layers, a composite electrophotographic plate can be obtained which has a wide photosensitive wavelength range, is particularly sensitive to long wavelengths, and has excellent repeatability and durability. Although the reason why the combination of the charge generating substance and the charge transporting substance of the present invention exhibits good characteristics is not clear, it is possible to obtain high sensitivity especially when positively charged, so that the combination of the charge generating substance and the charge transporting substance can be easily transferred from the charge generating substance to the charge transporting substance. , it is expected that electrons will be injected efficiently. The conductive support used in the composite electrophotographic plate of the present invention may be made of brass, aluminum, gold, copper, etc., and may be a sheet, thin plate, or It may be cylindrical and may be covered with a thin layer of plastic.
Also, metal coated paper, metal plastic sheet or
It may also be glass coated with a thin layer of aluminum iodide, copper iodide, indium 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. Further, a barrier layer may be provided on the conductive support or between the charge generation layer and the charge transport layer, if necessary. Next, the present invention will be specifically explained using examples. Example 1 1 part by weight of a β-type copper phthalocyanine pigment (manufactured by Dainippon Ink Co., Ltd., First Gen Blue-FGF) and 1 part by weight of a disazo pigment having the following structural formula (manufactured by Dainippon Ink Co., Ltd., Sumira First Blue 4135). Butyral resin (manufactured by Union Carbide, XYHL) 1
6% by weight solution using xylene as solvent The mixture was mixed in a ball mill (manufactured by Nippon Kagaku Togyo Co., Ltd., 3-inch pot) for 5 hours to obtain a charge-generating substance coating liquid, and this liquid was applied onto aluminum foil with a film thickness of 100 μm using an automatic applicator (Toyo Co., Ltd.). (manufactured by Seiki Co., Ltd.) and dried to form a charge generation layer.
The thickness of this layer is approximately 3 μm. Next, 3 g of poly-9-(p-vinylphenyl)anthracene and 2 g of 2,4-dinitrofluorenone, which are charge transport substances in the present invention, were dissolved in 40 ml of toluene.
This solution was applied onto the charge generation layer using an automatic applicator. Film thickness is approximately 8μ
It is m. The electrophotographic properties of the composite electrophotographic plate constructed in this example were evaluated using an electrostatic recording paper tester (manufactured by Kawaguchi Electric Co., Ltd., SP-428). In this case, a positive 5KV corona discharge is performed for 10 seconds to charge the surface (the surface potential immediately after charging for 10 seconds is V ₀
(V) is the initial potential), and after being left in the dark for 30 seconds (the surface potential during this time is expressed as V ₃₀ , V ₃₀ /V ₀ ×
100 (%) is the dark attenuation), and exposed with a tungsten lamp so that the surface illuminance is 20 lux.
Record the decay and time of the surface potential at this time,
White light sensitivity (halving exposure amount, _{E 50}
(lux seconds)). Spectral sensitivity is determined by irradiating spectra of each wavelength from a spectrometer instead of using a tungsten lamp, and calculating the time t (seconds) until V ₃₀ becomes 1/2 and the energy of each spectrum (μ
Spectral sensitivity (cm ² /erg) is expressed as the reciprocal of the product of W/cm ² ). Such a relationship can be shown in FIG. As a result, the characteristics of the electrophotographic plate of this example were as follows: initial potential of 650 (V), dark decay of 52%, and white light sensitivity of 3.0 lux·sec, values that pose no problem in practical use. Next, this electrophotographic plate was charged with a positive voltage of 5KV for 10 seconds in a dark place, and then contact exposure was performed using a semiconductor laser with an output of 5mW and a wavelength of 800nm.As a result of performing the phenomenon using the cascade method, a clear image was obtained. A visual image was obtained. Example 2 The mixing ratio (weight ratio) of ε-type copper phthalocyanine (manufactured by Toyo Ink Co., Ltd., Lionol Blue ESP), which is a charge generating substance, and a disazo pigment with the following structure was determined. In Example 1, 1 part by weight of butyral resin was added to 2 parts by weight of the charge generating substance using xylene as a solvent.
A charge generation layer (thickness: 3 μm) was formed using the same method as above.
was formed. Furthermore, the charge transport material poly-9
-(p-vinylphenyl)anthracene 3g,
2,4,7-trinitrofluorenone 2g, saturated polyester resin (manufactured by Toyobo Co., Ltd., Vylon
200), 20 ml of dichloromethane, and 20 ml of 1,2-dichloroethane were mixed to prepare a charge transport substance coating liquid. The preparation begins by completely dissolving the resin,
A subsequent method of adding the charge transport material is necessary to obtain a homogeneous coating. This coating liquid was applied onto the charge generation layer using an applicator and dried to form a charge transport layer (thickness: 13 μm). The electrophotographic properties of the composite type electrophotographic plate thus prepared were evaluated for white light in Examples. The results are shown in Table 1.

[Table] Sensitivity is improved by using a mixture of charge generating substances in this way. In order to understand the reason for this more accurately, the spectral sensitivities of these electrophotographic plates were measured. The results are shown in FIG. Curve A is for the case where only the ε-type copper phthalocyanine pigment is used as a charge generating substance, curve B is for the case where the ε-type copper phthalocyanine pigment: disazo pigment is 3:1 (weight ratio), and curve C is for the case where the ratio is 2:2. 1:3 is represented by curve D, and that using only disazo pigment is represented by curve E. In addition, as a comparative example, no charge generating substance was used, that is, poly-9-(p-vinylphenyl)
Curve F represents the spectral sensitivity of only the charge transport layer consisting of anthracene, 2,4,7-trinitrochlorenone, and a saturated polyester resin. As can be seen from Figure 2, when the disazo pigment, which is a charge-generating substance, is used alone (curve E), the wavelength
Sensitivity disappears above 700nm. In addition, the spectral sensitivity of the charge transport layer alone (curve F) is
Compared to composite electrophotographic plates, it has lower sensitivity, and its sensitive wavelength range is from 400 to 700 nm, with no sensitivity on the long wavelength side. However, when a mixture of charge-generating substances is used, not only does the sensitive wavelength range become wider, but E and F have low sensitivity especially at wavelengths of 600 nm or more, while B, C, and D are more sensitive than A. will improve. When an ε-type copper phthalocyanine pigment and a disazo pigment are combined to form a charge-generating substance, the characteristics are improved. It is thought that this is due to improved carrier generation, but the details are unknown. Example 3 1 part by weight of β-type copper phthalocyanine (manufactured by BASF, Heliogen Blue-7080), 1 part by weight of a monoazo Ca lake pigment having the following structure (manufactured by Dainichiseika Kaisha, Ltd., Brilliant Carmine 6B), and acrylic resin. A charge generation material coating liquid was prepared using 0.5 parts by weight of fat (manufactured by DuPont, Elvacite 2045) and xylene as a solvent in the same manner as in Example 1 to form a charge generation layer. The thickness of this layer is approximately 2.5 μm. Next, 3 g of bromide of poly-9-(p-vinylphenyl)anthracene (bromination rate 100% as a mono-substituted product for the anthracene nucleus) and 1 g of 2-nitrofluorenone were dissolved in 20 ml of tetrahydrofuran, and the same procedure as in Example was carried out. A composite type electrophotographic plate was obtained. The thickness of this charge transport layer is 20μ
It is m. As in Example 1, the electrophotographic characteristics were measured and found that the initial potential was 790 V, dark decay was 51%, and white light sensitivity was 2.6 lux·sec, which were acceptable for practical use. As a result of image forming tests performed as a light source, clear images were obtained. Example 4 1.5 parts by weight of β-type copper phthalocyanine pigment (manufactured by Dainippon Ink Co., Ltd., Dianine Blue LC), the same disazo pigment as in Example 2 was used as a charge generating substance, diethylamine was added, and charge generating substance concentrations were varied from 3 to 35% by weight. A coating liquid was prepared. After sufficiently dispersing the charged substance using ultrasonic waves, these liquids were applied onto aluminum foil using an automatic applicator in the same manner as in Example 1, dried thoroughly, and the film thickness was determined. Different charge generation layers were obtained. A charge transport layer having the same composition as in Example 1 was further formed on these charge generation layers (film thickness: 8 μm) to obtain a composite electrophotographic plate. Table 2 shows the results of evaluating these electrophotographic characteristics with respect to white light.

[Table] As shown, the film thickness of 1 μm has the highest sensitivity,
It was found that as the film thickness increases, the sensitivity tends to decrease. Example 5 In the same manner as in Example 1, a charge generation layer (thickness 3
μm) was obtained. Next, using the same charge transport material as in Example 3 and varying the amount of tetrahydrofuran as a solvent, composite electrophotographic plates with charge transport layers having different thicknesses were prepared, and their electrophotographic properties were investigated. The results are shown in Table 3.

[Table] As described above, as the thickness of the charge transport layer increases, the initial potential increases, but the sensitivity tends to decrease. Example 6 9-(p-vinylphenyl)anthracene monomer and 9-vinylcarbazole monomer in a molar ratio of 3
1 ml of a xylene solution containing 5 parts by weight of di-tert-butyl peroxide was sealed in 100 parts by weight of the mixture of 100 parts by weight of Co. 2 and 1 ml of a xylene solution containing 5 parts by weight of di-tert-butyl peroxide, and heated at 130 DEG C. for 15 hours to obtain a copolymer. A coating solution was prepared by adding 2,4,7-trinitrofluorenone to 1 part by weight of this copolymer and using 20 parts by weight of xylene as a solvent. Coating was performed with an applicator to obtain a composite electrophotographic plate. Table 4 shows the results of examining the electrophotographic properties of these electrophotographic plates.

[Table] Thus, as the amount of 2,4,7-trinitrofluorenone increases, the dark decay tends to decrease. Example 7 2 parts by weight of poly-9-(p-vinylphenyl)anthracene, 2,4,7-
Addition of 1 part by weight of trinitrofluorenone and the saturated polyester resin used in Example 2 to 1,3,
6,9,12 parts by weight of dichloromethane and 1,
A coating liquid was prepared using 2-dichloroethane (a mixed solvent at a volume ratio of 1:1) and a charge carrier and resin concentration of 8% by weight in order to eliminate the influence of film thickness.This coating liquid was used in Example 1. Coating was carried out using an automatic applicator on the charge generating layer of 100% to obtain a composite type electrophotographic plate.Table 5 shows the results of examining the electrophotographic properties of these plates.

[Table] As shown, as the amount of resin increases, the initial potential and dark decay improve, but the sensitivity decreases.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the change in surface potential over time of a composite type electrophotographic plate, and represents the calculation standard for the half-decrease exposure sensitivity. 3 is a graph showing the relationship between light wavelength and sensitivity in FIG.

Claims (1)

[Scope of Claims] 1. A composite electrophotographic plate in which a charge generation layer and an electron transfer type charge transport layer are provided in this order on a conductive support, the charge generation layer comprising a copper phthalocyanine pigment and a compound of the following general formula (D ), the charge transport layer is composed of a 9-(p-vinylphenyl)anthracene polymer, 9-(p- At least one selected from copolymers of vinylphenyl)anthracene monomers and other vinyl monomers and brominated 9-(p-vinylphenyl)anthracene polymers; and at least one nitrofluorenone represented by the following general formula (B). A composite electrophotographic plate for positive charging, characterized in that it consists of a mixture of However, X represents _-OCH3 , Cl group. However, m and n are integers, and 1≦(m+n)≦3 2 The amount of anthracene polymer and nitrofluorenone compounded in the charge transport layer is in the range of 0.1 to 3 parts by weight of nitrofluorenone per 1 part by weight of anthracene polymer. A composite type electrophotographic plate for positive charging according to claim 1, characterized in that: 3. The positive charging composite electrophotographic plate according to claim 1, wherein the charge transport layer has a thickness in the range of 5 to 30 μm. 4. The positive charging composite electrophotographic plate according to claim 1, wherein the charge transport layer has a thickness in the range of 0.5 to 5 μm.