GB2145835A - Electrophotographic plates - Google Patents

Abstract

An electrophotographic plate comprising a charge generating layer and a charge transporting layer each formed on an electroconductive support, a charge generating material contained in the charge generating layer being prepared by mixing phthalocyanine and a phthalocyanine derivative wherein the nuclei of phthalocyanine molecule are substituted with at least one kind of electron-attracting group, with an inorganic acid capable of forming a salt with phthalocyanine to obtain a mixture, and then pouring the thus obtained mixture into water or a basic substance to precipitate the charge generating material therefrom. <IMAGE>

Description

SPECIFICATION Electrophotographic plates This invention relates to an electrophotographic plate comprising a charge generating layer and a charge transporting layer which are formed on an electroconductive material.

In general, electrophotography includes a method comprises, as in a xerographic system, charging in the dark a plate prepared by forming photoconductive material such as selenium or cadmium sulfide into a thin film on a metal drum, irradiating a light image to the thus charged plate (exposure) thereby to form an electrostatic latent image on the plate, applying a toner to make a visible image (development), and transferring and fixing the visible image on paper or the like. Another method comprises, as in an electrofax system, forming a photoconductive layer (photosensitive layer) on paper, and forming a permanent visible image on the photoconductive layer by subjecting to charging, exposure, development and fixing.

Photoconductive materials now widely used in electrophotographic plates include inorganic compounds typical of which are amorphous selenium, cadmium sulfide, zinc oxide and the like.

Amorphous selenium has good characteristics as a photoconductive material but has a number of disadvantages that it is difficult to manufacture because vacuum deposition is essential for the manufacture of photoconductive layer, and care should be taken in handling because little flexibility of vacuum deposited film and high toxicity of the material, coupled with another disadvantage that it is expensive. Cadmium sulfide and zinc oxide are used in the form of a photoconductive layer in which these compounds are each dispersed in a binder resin. Since the photoconductive layer has a practical level of photosensitivity only when its resin/photoconductive material ratio by weight is in the range below 0.2-0.3, its mechanical properties such as flexibility, smoothness, hardness, tensile strength, abrasion resistance and the like are disadvantageously poor.This means that the photoconductive layer of the just-mentioned type cannot stand repeated use when employed as it is. Additionally, consideration should be given to cadmium sulfide with respect to its hygenic problem.

On the other hand, organic photoconductive compounds which are known, include polyvinyi- carbazole (PVK) and phthalocyanine.

These photoconductive materials are excellent in flexibility and processability but are not satisfactory in electrophotographic sensitivity when used singly in practical applications. Accordingly, it is necessary to chemically or optically sensitize these materials. Known chemical sensitizers are, for example, polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitro-9fluorenone (TNF), 2,4,5-tetranitro-9-fluorenone (TENF) and the like, quinones such as anthraquinone, and nitrile compounds such as tetracyanoethylene. Examples of optical sensitizers include xanthene dyes, quinoline dyes and the like.In this connection, however, when these sensitizers are used in such amounts in electrophotographic plates that they have a practical level of photosensitivity, their own relatively poor antistaticity and light resistance will present the problem that fatigue phenomena occur considerably in the electrophotographic plates when they are subjected to continuous charging and exposing operations. When used as a chemical sensitizer, TNF and TENF exhibit a very excellent sensitizing effect and, in fact, are often used in organic photoconductors. However, these sensitizing materials are expensive, so that if they are added in large amounts in order to attain a necessary level of photosensitivity, the resulting electrophotographic plates will have not only a problem of cost, but also a hygenic problem on human bodies, thus leaving doubts as to the use thereof.

A method using phthalocyanine derivatives as well as phthalocyanines has also been proposed. This method requires an intense mechanical mixing treatment, by which phthalocyanine and phthalocyanine derivatives are uniformly mixed, resulting in obtaining an electrophotographic plates with excellent electrophotographic characteristics. However, the fairly long-time mechanical mixing treatment requires great labor, imposing a great limitation on the practice of this method from the industrial viewpoint. In addition, the properties required for electrophotographic plates are not necessarily satisfied fully.

On the other hand, there are studied various methods which form a charge generating layer and a charge transporting layer on an electroconductive support thereby to obtain a function separated, laminated photosensitive plate. There are known such laminated photosensitive plates, one of which comprises a "charge generating layer/charge transporting layer" laminate formed on an electroconductive support and the other comprises a "charge transporting layer/charge generating layer" laminate formed on an electroconductive support. These laminated photosensitive plates are advantageous in that they when used will decrease in induction effects caused by capture of the generated charge as is generally seen in mono-layer photosensitive plates and improve in gradation.

This invention has its object to provide a function separated, laminated photosensitive plate having both excellent gradation and electrophotographic characteristics by using a charge generating layer in which a specific phthalocyanine charge generating material is used.

The electrophotographic plates of this invention comprise a charge generating materialcontaining layer (charge generating layer) and a charge transporting layer each formed on an electroconductive support, the charge generating material being obtained by (A) mixing (1) phthalocyanine and (2) a phthalocyanine derivative in which the benzene nuclei of phthalocyanine molecule are substituted by at least one kind of electron-attracting group selected from nitro group, cyano group, a halogen atom, sulfonic group and carboxyl group, with (3) an inorganic acid capable of forming a salt with phthalocyanine to obtain a mixture, and then (B) pouring the thus obtained mixture into water or a basic substance to precipitate the charge generating material therefrom.

Phthalocyanines used in the present invention are metal-free phthalocyanines, metal-phthalocyanines and mixtures thereof. Metals of metal-phthalocyanines include, for example, copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminium, gallium, indium, lanthanum, neodymium, samarium, europium, gadolinium. dysprosium, holmium, erbium, thulium, ytterbium, lutetium, titanium, tin, hafnium, lead, thorium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium.

osmium, platinum and the like. Alternatively, the central nucleus of phthalocyanine may not be metal atoms, but may be trivalent or higher valent metal halides. Metal-free phthalocyanines and metal-phthalocyanines in which the metal is copper, cobalt, lead, zince or the like, are preferable. In addition, low halogenated phthalocyanines may be used. Phthalocyanines are compounds which are well known as pigments and phthalocyanines obtained by any preparation methods may be used in the practice of the invantion. Phthalocyanines called "crude" in the field of pigment and phthalocyanines made into a pigment, may be used.

Phthalocyanine derivatives according to the invention are those in which the benzene nuclei of the phthalocyanine molecule are substituted with at least one kind of an electron attracting group selected from nitro group, cyano group, a halogen atom, sulfone group and carboxyl group. These phthalocyanine derivatives can be obtained by using as starting materials nitro, cyano, halogen, sulfone or carboxyl-substituted phthalonitrile, phthalic acid, phthalic anhydride or phthalimide or using as the starting materials a mixture thereof with non-substituted phthalonitrile, phthalic acid, phthalic anhydride or phthalimide. Methods for the preparation of phthalocyanine derivatives are not particularly limited to any specific one. The number of the substituents in one molecule of phthalocyanine derivatives is generally in the range of 1-16, preferably 1-8 and more preferably 1-4.It will be noted that the number of substituents varies depending on the manner of preparation and, in many cases, phthalocyanine derivatives having different numbers of substituents are obtained as a mixture. Further, for example, a phthalocyanine derivative having nitro and cyano groups, a phthalocyanine derivative having nitro groups and a phthalocyanine derivative having cyano groups, may be used in admixture. Still further, phthalocyanine derivatives other than those according to this invention may partly be used.

The pnthalocyanine of phthalocyanine derivatives used herein may be a metal-free one or a metal-phthalocyanine in which the metal is copper, nickel, cobalt, iron, sodium, lithium, calcium, magnesium, aluminum or the like.

The mixing ratio by weight of a phthalocyanine to a phthalocyanine derivative is in the range of 100:0.01-20, preferably 100:0.1-5. The use of less than 0.01 part by weight of the phthalocyanine derivative per 100 parts by weight of the phthalocyanine will result in producing an electrophotographic plate having insufficient photosensitivity, whereas the use of more than 20 parts by weight thereof will result disadvantageously in increasing the dark decay rate and rendering the resulting plate unsuitable for practical applications.

The phthalocyanine and phthalocyanine derivatives used herein may be prepared by the following typical methods including: A nitrile method comprises heating in an organic solvent such as an alcohol, phthalodinitrile and/or nitro group-, cyano group- or like group- substituted phthalodinitrile, together with a strong basic catalyst such as ammonium alcoholate, in the presence or absence of a metal salt; a method comprises heating phthalic anhydride and/or nitro group-, cyano group- or like groupsubstituted phthalic anhydride, urea and a metal salt using molybdic acid, ammonium or the like as the catalyst in the presence or absence of a solvent; and a method comprises using aminoiminoisoindrenine.

Inorganic acids capable of forming salts with phthalocyanines in this invention are, for example, sulfuric acid, orthophosphoric acid, pyrophosphoric acid, chlorosulfuric acid, hydrochloric acid, hydroiodic acid, hydrofluoric acid, hydrobromic acid and the like. These inorganic acids are those which are employed in known methods including acid pasting, acid slurry and the like methods for phthalocyanines. The salt formation can be effected by known methods including: for instance, a method comprises dissolving phthalocyanines in the inorganic acids and then charging the resulting solution into water or the like (acid pasting method); a method comprises slurrying phthalocyanines in an inorganic acid salt and then charging the resulting slurry into water or the like (acid slurry method), and a method comprises decomposing an inorganic acid salt of phthalocyanines with a basic material such as ammonia gas thereby precipitating phthalocyanines.

The charge generating material obtained as mentioned above is coated, together with a binder resin, on an electroconductive support or a charge transporting layer to form a charge generating layer thereon; it is coated, together with a solvent, to form a charge generating layer; or it may form a charge generating layer by vapor deposition or sputtering. In the latter two cases, it is preferable except for further formation of a protective layer that the charge generating layer be laminated on the conductive support and the charge transporting layer be then laminated on the charge generating layer, that is, it is preferable that the resulting laminate be an "electroconductive support/charge generating layer/charge transporting layer" laminate.

In a case where a charge generating layer is formed with a binder resin, the charge generating material, the binder resin, a solvent and the like are treated on a knead-disperser such as a ball mill or attriter to obtain a uniform dispersion therefrom, after which the thus obtained dispersion is coated on an electroconductive support to form the charge generating layer thereon.

The binder resins used herein are insulating ones which have a specific volume resistance of at least 107 S2.cm and include, for example, melamine resins, epoxy resins, silicone resins, polyurethane resins, polyester resins, alkyd resins, acrylic resins, xylene resins, vinyl chloridevinyl acetate copolymer resins, polycarbonate resins, cellulose derivatives and the like. Photoconductive binder resins such as polyvinylcarbazole, may also be used.

A composition comprising the charge generating material, the binder resin and the like is applied onto an electroconductive support, such as an aluminium plate, conductivity-imparted paper or a plastic film, ordinarily employed in electrophotographic plates thereby forming a photosensitive layer. Before its application to form a film, the composition may be admixed with a solvent, if necessary, to control its viscosity. Applicators useful for the application include air doctor coater, blade coater, rod coater, reverse roll coater, spray coater, hot coater, squeeze coater, gravure coater and the like. After the application, the composition so applied is suitably dried as required.

The charge generating layer according to the invention has a resin/charge generating material ratio by weight of at least 1 and is high in resin content, physical strength and flexibility as compared with, for example, a photosensitive plate using zinc oxide. In addition, the charge generating layer is practically advantageous in that when used, it will exhibit high strength of bond to a conductive support, satisfactory moisture resistance, less variation in quality with the lapse of time and no problems as to toxicity and that it is easy to fabricate and inexpensive.

The thickness of the charge generating layer is usually about 0.01-10 jum, is about 0.5-10 ,um when it is formed by methods other than vapor deposition and sputtering methods, and is about 0.01-2 ,um when it is formed by vapor deposition and like methods.

The charge transporting layer laminated on the charge generating layer is a layer which transports the charge generated at the charge generating layer to the surface of the photosensitive plate. The charge transporting layer is desired to be transparent to the lights by which the charge generating layer is photosensitized, and the formation thereof is effected by dissolving a charge transporting material, together with or without a resin to disperse said material therein, and then coating the resulting solution on the charge generating layer or conductive support.

The charge transporting material which may be used alone (without the resin), includes polyvinyl carbazole, derivatives thereof or a vapor deposited film of selenium. On the other hand, the resin for dispersing and dissolving the charge transporting material includes polycarbonate or polyester and, in this case, the mixing ratio by weight of the charge transporting material to the resin is in the range of preferably 0.1 to 1, more preferably 0.3 to 0.8. The thickness of the charge transporting layer is not particularly limited but is in the range of usually 5-50 pm.

The charge transporting materials used herein include carbazole, N-ethylcarbazole, N-vinylcarbazole, N-isopropylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2phenylnaphthalene, azapyrene, 2, 3-benzochrysene, 3, 4-benzopyrene, fluorene, 1, 2-benzofluorene, 2, 3-benzofluorene, 4-(2-fluorenylazo) resorcinol, 4-(2-fluorenylazo)m-cresol, 2-p-anisoleam inofluorene, p-diethylamino-azobenzene, 1 -(2-thiazolylazo)-2-naphthol, 4-anisoleaminoazo-benzene, N, N-dimethyl-p-phenylBzoaniline, p-(dimethyl-amino) stilbene, 1, 4-bis(2-methylstyryl) benzene, 9-(4-diethylaminostyryl) anthracene, 2, 5-bis(4-diethyl-aminophenol)-1, 3, 5-oxadiazole, 1 .phenyl-3-(p-diethyl-aminostyryl)-5-(p-diethylaminophenyl) pyrazoline, 1 -phenyl-3-methyl-5-pyra- zolone, 2-(m-naphthyl)-3-phenyloxazole and p-diethylaminobenzaldehyde-(diphenylhydrazone).

The resins (binders) used herein include polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polycarbonate, polystyrene, styrene-butadiene copolymers, polyester, polyvinylcarbazole, polyurethane, epoxy resins, phenoxy resins, polyamide, acrylic resins and silicone resins.

In the practice of this invention, the charge generating layer and charge transporting layer may be incorporated with e type phthalocyanine, P type phthalocyanine and/or a sensitizer other than phthalocyanines as well as other additives, as required.

The electrophotographic plates of this invention may also be used as electrophotographs for use in the preparation of printing plates.

Since the electrophotographic plates of this invention decrease in induction effects, they have satisfactory gradation and excellent sensitivity and are further advantageous in that they are particularly improved in resistance to fatigue caused by repetition of charging and exposure to light in a case where they are of an "electroconductive support/charge generating layer/charge transporting layer" structure.

This invention will be better understood by the following Examples and Comparative Examples wherein parts are by weight unless otherwise specified.

Example 1 Forty (40) parts of copper phthalocyanine and one part of mononitro copper phthalocyanine were dissolved under thorough agitation in 500 parts of a 98% concentrated sulfuric acid. The resulting solution was charged into 1000 parts of water while agitating thoroughly, thereby to precipitate a composition comprising copper phthalocyanine and mononitro copper phthalocyanine, after which the thus precipitated composition was filtered off. washed with water and then dried at 1 20 C at a reduced pressure.

Ten (10) parts of the thus dried composition, 36 parts of acrylpolyol (produced under the tradename of Takelac UA-702 by Takeda Pharmaceutical Industrial Co., Ltd.), 5 parts of epoxy resin (produced under the tradename of Epon 1007 by Shell Chemical Co.) and 50 parts of a composition containing methyl ethyl ketone and Cellosolve acetate in a mixing ratio of 1:1, were mixed and kneaded on a ball mill for 24 hours to prepare a photoconductive coating material which was then coated to a depth of about 1 C1 on an aluminum support thereby forming a charge generating layer.

Then, 10 parts of polycarbonate resin (produced under the tradename of Panlite L by Teijin Limited) and 3 parts of polyester resin (produced under the tradename of PE-200 by Goodyear Co.) were mixed together in 100 parts of a mixed solvent of tetrahydrofuran and toluene (mixing ratio by weight of 9:1) and then incorporated with 9 parts of p-diethylaminobenzaldehyde- (diphenylhydrazone) and 0.02 parts of silicone oil to obtain a liquid. The thus obtained liquid was coated to a depth of about 1 5 IL on the charge generating layer and then dried at 80"C to form a charge transporting layer thereon thereby obtaining a laminate-type electrophotographic plate.

Example 2 The procedure of Example 1 was followed except that tetracyano nickel phthalocyanine was substituted for the mononitro copper phthalocyanine, thereby to obtain a laminate-type plate.

Example 3 The procedure of Example 1 was followed except that tetranitro copper phthalocyanine was substituted for the mononitro copper phthalocyanine, thereby to obtain a laminate-type plate.

Example 4 Thirty (30) parts of metal-free phthalocyanine and 0.5 parts of dinitro copper phthalocyanine were dissolved under thorough agitation in 500 parts of a 98% concentrated sulfuric acid. The resulting solution was poured into 3000 parts of water to precipitate a phthalocycanine-type composition which was then filtered off, washed with water and dried at 120"C under a reduced pressure.Then, 5 parts of the thus dried compositicn, 20 parts of thermoplastic acryl resin (produced under the tradename of OXL-97 by Mitsui Toatsu Chemicals Inc.) and 30 parts of a mixture of butyl acetate and Cellosolve acetate (mixing ratio 1:1) were mixed and kneaded on a ball mill for 24 hours to prepare a photoconductive coating material which was coated to a depth of about 1 IL on an aluminum support to form a charge generating layer.

Then, 10 parts of polycarbonate resin (Panlite L), 5 parts of polyester resin (PE-200) and 5 parts of acryl resin (produced under the tradename of Dianal by Mitsubishi Rayon Co.) were dissolved in 1 50 parts of a mixed solvent containing tetrahydrofuran and toluene (mixing ratio 9:1) and then incorporated with 1 2 parts of 2, 5-bis(4-diethylaminophenyl)- 1, 3, 4-oxadiazole and 0.02 parts of silicone oil to obtain a liquid. The thus obtained liquid was coated to a depth of about 15 p on the charge generating layer and then dried at 80"C to form a charge transporting layer thereon thereby obtaining a laminate-type electrophotographic plate.

Example 5 The procedure of Example 4 was followed except that tetracarboxy copper phthalocyanine was substituted for the dinitro copper phthalocyanine, thereby to obtain a laminate-type plate.

Example 6 The procedure of Example 4 was followed except that in the formation of the charge transporting layer, 1 -phenyl-3-(p-diethylaminostyryl)-5-(p-d iethylaminophenyl)-2-pyrazoline was substituted for the 2, 5-bis(4-diethylaminophenyl)-1, 3, 4-oxadiazole, to obtain a plate.

Example 7 The procedure of Example 6 was followed except that copper phthalocyanine and dinitro dicarboxy copper phthalocyanine were substituted in the formation of the charge generating layer, thereby to obtain a plate.

Example 8 Ten (10) parts of the charge generating material-containing composition obtained in Example 1, 32 parts of a thermosetting acrylic resin (produced under the tradename of Acrydie A 405 by Dai Nippon Ink Chemical Industrial Co., Ltd.), 8 parts of a melamine resin (produced under the tradename of Super Beckamine J820 by the above Co., L.) and 50 parts of a mixture of butyl acetate and Cellosolve acetate (1:1) were mixed and kneaded together on a ball mill for 24 hours thereby to prepare a photoconductive coating material, after which the thus prepared coating material was coated to a depth of about one IL on an aluminum support and then cured at 150"C thereby obtaining a charge generating layer.

Then, the same charge transporting material as used in Example 1 was coated to a depth of about 1 5 it in the same manner as in Example 1 and dried at 80"C to form a charge transporting layer thereby obtaining a laminate-type plate.

Comparative Example 1 Ten (10) parts of type copper phthalocyanine, 32 parts of thermosetting acryl resin (Acrydie A 405), 8 parts of melamine resin (Super Beckamine J820) and 50 parts of a mixture of butyl acetate and Cellosolve acetate (1:1) were mixed and kneaded on a ball mill for 24 hours to prepare a photoconductive coating material which was then coated to a depth of about one IL on an aluminum support thereby form a charge generating layer thereon.

Then, the same charge transporting material as used in Example 1 was coated to a depth of about 1 5 it in the same manner as in Example 1 and dried at 80"C to form a charge transporting layer thereby obtaining a laminate-type plate.

Comparative Example 2 The procedure of Comparative Example 1 was followed except that metal4ree phthalocyanine was substituted for the fl-type copper phthalocyanine, thereby to obtain an electrophotographic plate.

Comparative Example 3 The procedure of Example 4 was followed except that in the formation of the charge generating layer, a-type copper phthalocyanine was substituted for the metal4ree phthalocyanine and dinitro copper phthalocyanine, thereby to obtain a plate.

The plates so far obtained were measured for surface potential (V) by the use of a commercially available Carlson-type electrophotographic duplicator when the plate was subjected to corona charge at - 6.5 KV for 0.2 seconds. Further, the amount of light exposure (E 1 /2) required for each potential (V) being decreased to one-half (1 /2) thereof was measured.

The results are as shown in the following Table.

Table V(-v) E 1/2 (Lux.sec) Example 1 535 3.0 Example 2 560 4.0 Example 3 510 2.8 Example 4 525 3.2 Example 5 570 4.2 Example 6 553 3.4 Example 7 560 3.6 Example 8 540 3.2 Comp. Example 1 580 13.5 Comp. Example 2 585 8.2 Comp. Example 3 580 7.1 As is seen from the above results, the plates of this invention are very highly sensitive and have sensitivity in the region of long wavelength. Thus, they are excellent plates which may be used in, for example, ordinary duplicators and printers using a semiconductive laser (A = 750-850 ELm) as the light source.

Claims (11)

1. An electrophotographic plate comprising a charge generating layer and a charge transporting layer each formed on an electroconductive support, the charge generating layer containing a charge generating material prepared by (A) mixing (1) phthalocyanine and (2) a phthalocyanine derivative wherein the benzene nuclei of phthalocyanine molecule are substituted with at least one kind of electron-attracting group selected from the group consisting of nitro group, cyano group, halogen atoms, sulfonic group and carboxyl group, with (3) an inorganic acid capable of forming a salt with phthalocyanine to form a mixture, and then (B) pouring the thus formed mixture into water or a basic substance to precipitate the charge generating material therefrom.

2. An electrophotographic plate according to claim 1, wherein the electroconductive support, the charge generating layer and the charge transporting layer are laminated one upon another in that order.

3. An electrophotographic plate according to claim 1, wherein an electric charge transporting material for the charge transporting layer is carbazole, N-ethylcarbazole, N-vinylcarbazole, Nisopropylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2,3-benzochrysene, 3,4-benzopyrene, fluorene, 1 ,2-benzofluorene, 2,3-benzofluorene, 4-(2-fluorenylazo) resorcinol, 4-(2-fluorenylazo)m-cresol, 2-p-anisoleaminofluorene, p diethylaminoazobenzene, 1 -(2-thiazolylazo)-2-naphthol, 4-anisoleaminoazobenzene, N, N-dimethyl-p-phenylazoaniline, p-(dimethylamino) stilbene, 1 ,4-bis(2-methylstyryl) benzene, 9-(4-diethylaminostyryl) anthracene, 2, 5-bis(4-diethylaminophenol)- 1,3, 5-oxadiazole, 1 -phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl) pyrazoline, 1 -phenyl-3-methyl-5-pyrazolone, 2-(m-naphthyl)-3-phenyloxazole or p-diethylaminobenzaldehyde-(diphenylhydrazone).

4. An electrophotographic plate according to claim 1, wherein the electroconductive support is an aluminum plate, paper treated to be made conductive, or a plastics film.

5. An electrophotographic plate according to claim 1, wherein the inorganic acid is sulfuric acid, orthophosphoric acid, pyrophosphoric acid, chlorosulfonic acid, hydrochloric acid, hydroiodic acid, hydrofluoric acid or hydrobromic acid.

6. An electrophotographic plate according to claim 1, wherein the phthalocyanine derivative is one in which the phthalocyanine molecule is substituted with 1 to 8 electron-attracting groups.

7. An electrophotgraphic plate according to claim 1 or 6, wherein the at least one member (1) is phthalocyanine and a phthalocyanine derivative in a ratio by part of 100:0.01-20.

8. An electrophotographic plate according to claim 1, 6 or 7, wherein the charge generating material is dispersed in a binder resin.

9. An electrophotographic plate according to claim 8, wherein the binder resin is an insulating one having a specific volume resistance of at least 107 S2.cm which is a melamine resin, epoxy resin, silicone resin, polyurethane resin, polyester resin, alkyd resin, acryl resin, xylene resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate resin or cellulose derivative.

10. An electrophotographic plate according to claim 8, wherein the binder resin is a photoconductive one which is pclyvinylcarbazole.

11. An electrophotograpahic plate according to Claim 1, substantially as described in any one of non-comparative Examples 1 to 8.