JPH08272122A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] [Purpose] Electrophotographic photosensitive material that is excellent in abrasion resistance during repeated use and has a small residual potential, which results in high-speed response and does not deteriorate the quality of copied images even when a large number of continuous copies are made. To provide the body. An electrophotographic photoreceptor having at least a photosensitive layer, an intermediate layer, and a protective layer formed by a dry film forming method on a conductive support, wherein the intermediate layer contains a charge transport substance. Characteristic electrophotographic photoreceptor. An electrophotographic photoreceptor having at least a photosensitive layer and a protective layer formed by a dry film forming method on a conductive support, wherein the photosensitive layer contains a polymer charge transport substance. Photoreceptor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in copying machines, laser printers, laser facsimiles and the like.

[0002]

2. Description of the Related Art As the electrophotographic method, the Carlson method and various modifications thereof are known, and are widely used in copying machines, printers, facsimiles and the like. As photoreceptors used in these electrophotographic methods, those using organic photosensitive materials are increasing in price because they are low in price, non-polluting and suitable for mass production. The organic electrophotographic photoreceptor includes a photoconductive resin type typified by polyvinylcarbazole (PVK), PVK
A charge transfer complex type represented by -TNF (2,4,7-trinitrofluorenone), a pigment dispersion type in which a conductive pigment such as a phthalocyanine compound is dispersed in a resin, and a charge generation layer formed separately. Function-separated type photoreceptors and the like that are used in combination with a charge transport layer are known. In the function-separated electrophotographic photoconductor, when the photoconductor is charged and then irradiated with light, the light passes through the transparent charge transport layer and is absorbed by the charge generating substance in the charge generating layer. Injected into the layer. Then, the charge carriers move in the charge transport layer according to the electric field formed by charging, neutralize the charges on the surface of the photoconductor and form an electrostatic latent image.

The charge transport material is mainly developed as a low molecular weight compound, but since the low molecular weight compound alone has no film-forming property, it is usually used by being dispersed and mixed in a binder resin. However, the charge transport layer composed of a low molecular weight charge transport material and an electrically inactive binder resin is generally soft, and therefore, when repeatedly used by the Carlson method, there is a drawback that film abrasion is likely to occur. Further, a photoconductive layer mainly composed of selenium or a selenium alloy is provided on a conductive support; an inorganic photoconductive material such as zinc oxide or cadmium oxide is dispersed in a binder resin;
Amorphous silicon is used; and other inorganic electrophotographic photoreceptors are known. With respect to these electrophotographic photoconductors, the demand for reliability capable of guaranteeing high image quality for a long time is increasing year by year. However, if the photoconductive layer is exposed, it is likely to be damaged by corona discharge at the time of charging, and at the time of copying, it is likely to be physically or chemically damaged by contact with other members. Further, if the photoconductive layer is exposed, the layer is easily damaged even when the photoconductor is stored. If the photoconductive layer is damaged, the reliability of the photoconductor is lowered. Therefore, various attempts have been made to provide a protective layer on the surface of the photoconductor as described below.

For example, an organic film is attached to the surface of the photosensitive layer (Japanese Patent Publication No. 38-15446) or an inorganic oxide layer is provided (Japanese Patent Publication No. 43-14517); an insulating layer is formed after an adhesive layer is formed on the surface of the photosensitive layer. (Japanese Patent Publication Sho 43-
No. 27591); an amorphous silicon layer formed on the surface of the photosensitive layer by a plasma CVD method, a photo CVD method, or the like (Japanese Patent Laid-Open Publication No.
No. 179859), or a layer of silicon nitride or silica having an amorphous structure (Japanese Patent Laid-Open No. 59-58437); and the like, an electrophotographic photoreceptor having a protective layer is disclosed. However, when the protective layer is electrophotographically high in resistance (10 ¹⁴ Ω · cm or more), undesired phenomena such as increase in residual potential and charge accumulation during repeated use are likely to occur. Therefore, it is not preferable in practical use. In order to solve this problem, the protective layer is a photoconductive layer (Japanese Patent Laid-Open Nos. 48-38427 and 4).
9-10258, JP-A-43-16198, USP-2901348, etc.), and a charge transfer agent such as a dye or a Lewis acid is added to the protective layer (JP-A-44-8).
34, JP-A-53-133444, etc.),
A method has been proposed in which metal or metal oxide fine particles are added to control the resistance of the protective layer (JP-A-53-3338). However, in these methods, the amount of light that is absorbed by the protective layer and reaches the photoconductive layer is reduced,
As a result, there arises a problem that the sensitivity of the electrophotographic photosensitive member is lowered.

In Japanese Patent Laid-Open No. 57-30846, metal oxide particles having an average particle size of 0.3 μm or less are dispersed in a surface protective layer as a resistance control agent, whereby it is transparent to visible light and electrically. A method of providing a protective layer with controlled resistance is disclosed. The electrophotographic photosensitive member having the layer has less deterioration in sensitivity, the mechanical strength of the surface protective layer is increased, and the durability is improved. However, when this photoconductor is incorporated in an actual copying machine, there is a drawback that a residual potential is generated and a background stain is generated on an image. This residual potential is generated by the residual charges accumulated on the surface protective layer, and increases remarkably especially at low temperature and low humidity. In order to eliminate the above-mentioned drawbacks, a method has been proposed in which a low-molecular-weight charge transport material and a metal or metal oxide fine powder are added to the protective layer (JP-A-4-281461). When a low-molecular-weight charge transporting substance is added to the protective layer, a remarkable effect in reducing the residual potential is recognized, but there is a drawback that the abrasion of the surface protective layer due to repeated use becomes larger than that in the case of no addition. Cannot be said to be a sufficiently satisfactory improvement.

In recent years, a protective layer obtained by a dry film forming method such as a plasma CVD method, a photo CVD method or a sputtering method has advantages such as high hardness and no need for a solvent. For example, a protective layer made of amorphous carbon or hard carbon (JP-A-60-249155), a diamond-like carbon protective layer (JP-A-61-255352),
High hardness insulating layer containing carbon as a main component (Japanese Patent Laid-Open No. 61-26)
4355), a protective layer composed of an amorphous hydrocarbon film produced by glow discharge (JP-A-63-220166-9).
Japanese Patent Laid-Open Publication No. 63-2).
64766), a protective layer formed of a film deposited by a glow discharge decomposition method (JP-A-2-50166).
Etc. are disclosed. These protective layers are very hard and therefore have high abrasion resistance, but since the protective layers do not have a charge transporting ability, the residual potential increases. In addition, since it is hard, a large difference in hardness occurs between the lower photosensitive layer, and when internal stress is applied, there are problems such as cracking and peeling of the protective layer, and dry film formation of the protective layer. At the same time, the photosensitive layer may be damaged and the characteristics of the photosensitive member may be deteriorated. The latter two can be solved by providing an intermediate layer made of a polymer material that is not easily damaged between the protective layer and the photosensitive layer, but the residual potential of the photoconductor provided with the dry film-forming protective layer is increased by the conventional technique. It is difficult to solve.

[0007]

DISCLOSURE OF THE INVENTION The present invention has excellent wear resistance during repeated use and has a small residual potential, which results in high-speed response and deteriorates the quality of copied images even when a large number of continuous copies are made. It is an object of the present invention to provide an electrophotographic photoreceptor that does not.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted earnest research for developing an electrophotographic photosensitive member capable of solving the above-mentioned problems. That is, research has been advanced on a method for preventing the residual potential of the protective layer from rising without impairing the purpose and characteristics of the protective layer that protects the photoconductive layer from physical and chemical damage.
In addition, a method for preventing a decrease in wear resistance caused by adding a low-molecular-weight charge transport material or the like for preventing the increase in residual potential was examined. As a result, a conductive intermediate layer for the purpose of preventing damage to the photosensitive layer, improving adhesion, and buffering internal stress that occurs during dry process protective layer film formation, or a photosensitive layer containing a polymer charge transport material and a dry layer It was found that the above problems can be solved by combining with a protective layer formed by the method, and the present invention has been completed.
That is, according to the present invention, in an electrophotographic photoreceptor having at least a photosensitive layer, an intermediate layer, and a protective layer formed by a dry film forming method on a conductive support, the intermediate layer contains a charge transport substance. An electrophotographic photosensitive member is provided. Further, according to the present invention, there is provided the electrophotographic photosensitive member, wherein at least a part of the charge transport material contained in the intermediate layer is a polymer charge transport material. Further, according to the present invention, in an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer formed by a dry film forming method on a conductive support, the photosensitive layer contains a polymer charge transporting substance. An electrophotographic photosensitive member is provided.

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having high abrasion resistance during repeated use, low residual potential, and high-speed response. Although the reason for this is not clear, charge injection from the photosensitive layer to the protective layer is facilitated because the intermediate layer has a charge transporting ability, and therefore the photosensitive layer / intermediate layer interface, the intermediate layer, the intermediate layer / protective layer interface, and the protective layer are protected. Reducing residual charge accumulation in layers, etc .: Since the intermediate layer or the photosensitive layer contains a polymer charge transporting substance, the charge transporting sites are densified to increase the charge transfer rate. High speed responsiveness is realized due to the small number: the intermediate layer or the charge transport layer is composed only of the polymer, so that the difference in hardness between the protective layer formed by the dry method and the lower layer of the layer is reduced. , Which reduces internal stress strain due to hardness differences:
Since the lower layer of the protective layer is composed only of polymer, physical and chemical resistance increases, so that even if a protective layer is formed on the layer by a dry method, it is less likely to be damaged. ; It may depend on etc.

Next, the materials constituting the electrophotographic photosensitive member of the present invention will be described. First, the polymer charge transport substance will be described in detail. The polymer charge transport material used in the present invention is a polymer having a carbazole ring, a polymer having a hydrazone structure, polysilylene, a polymer having a tertiary amine structure, and the like, and the weight average molecular weight thereof is 1,000.
As described above, it is preferably 2,000 to 2,000,000. Further, when the ionization potential (hereinafter abbreviated as Ip) is smaller than the value obtained by adding 0.2 eV to the Ip value of the charge generating substance, the photosensitivity is high, and a typical polymer used in the present invention. Some of the charge transport materials are specifically described as follows. (A) Polymer containing carbazole ring Poly-N-vinylcarbazole, poly-N-acrylamidomethylcarbazole (polymer described in JP-A-50-82056), halogenated poly-N-vinylcarbazole (special Polymers described in JP-A-54-9632), poly-N-acrylamidomethylcarbamoylalkylcarbazoles (polymers described in JP-A-54-11737), and repeating units represented by the following general formula (1). A carbazole-based polycarbonate containing a unit and a repeating unit represented by the following general formula (2) (JP-A-4-18).
Polymers described in Japanese Patent No. 3719), and others.

[0011]

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[0012]

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[Chemical 4]

(B) Polymer Containing Hydrazone Structure Polystyrene derivative containing hydrazone structure having repeating unit represented by the following general formula (3) (JP-A-57-784)
No. 02), a hydrazone structure-containing polymer having a repeating unit represented by the following general formula (4) (polymer described in JP-A-3-50555), and others.

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[Chemical 6] R in the general formula (4) represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxy group or a dialkylamino group.

(C) Polysilylene Polymer A polysilylene polymer having a repeating unit represented by the following general formula (5) (polymer described in JP-A-63-285552), the following general formula (6) and / or Alternatively, a polysilylene polymer having a repeating unit represented by (7) (polymer described in JP-A-5-19497) and a polysilylene polymer having a repeating unit represented by the following general formula (8) Polymers described in JP-A 5-70595),
Other.

[Chemical 7] R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in the general formula (5) may be the same or different, but these may be an alkyl group or aryl group which may be substituted, or an alkoxy group. Represents a group. Further, n, m and p represent the proportion of the monomer unit in the polysilylene compound.

[0015]

Embedded image R ¹ and R ² in the general formula (6) and R ³ and R ⁴ in the general formula (7) may be the same or different, but they may be hydrogen atom, halogen atom, ether group or substituted. Represents a good alkyl group.

[Chemical 9] R ⁵ , R ⁶ , R ⁷ and R ⁸ in the general formula (8) may be the same or different, but these are a hydrogen atom or a substituted or unsubstituted alkyl group, alkoxy group, alkenyl group, aryl group, It represents an alkylsilyl group or an arylsilyl group. In addition, n represents an integer.

(D) Polymer containing a tertiary amine structure N, N-bis (p-tolyl) -4-aminopolystyrene, an arylamine-containing polyhydroxy ether represented by the following general formula (9) (special Polymers described in Japanese Unexamined Patent Publication No. 64-1728), and polymeric tertiary arylamine compounds represented by the following general formula (10) (JP-A-64-13).
No. 061), a polymer tertiary arylamine compound represented by the following general formula (11) (polymer described in JP-A No. 64-19049), and the following general formula (12): A copolymer having a tertiary amine structure represented (polymer described in JP-A-2-167335),
Copolymers containing a tertiary amine structure represented by the following general formula (13) (copolymers described in JP-A-5-40350), tertiary amines represented by the following general formula (14). Polymers having a structure (polymers described in JP-A-5-66598) and the like.

[0017]

[Chemical 10] R in the general formula (9) represents a hydrogen atom, a methyl group or an ethyl group, and m represents an integer of 4 to 1000. Also,
A is an arylamine group represented by the following (A), and B is an arylamine group represented by the following (A) or a divalent bonding group represented by the following (B).

[Chemical 11] Ar ^{1 in} (A) and (B) represents one kind of divalent bonding group selected from the following a to c, and Ar ² represents one kind of monovalent bonding group selected from the following d to f. And n and p represent 0 or 1. Further, Z in (A) represents one type of divalent bonding group selected from the following g to k, and V in (B) represents a methylene group, an isopropylidene group, a phenylene group, a cyclohexylidene group, -O. -Or-S- is represented.

[0018]

[Chemical 12]

[0019]

[Chemical 13] In the general formula (10), n represents an integer of 5 to 5000 and m represents 0 or 1. Z is the following (a), (b),
Ar ² is selected from the group consisting of the following (f), (g) and (c), and one divalent bonding group selected from the group consisting of (c), (d) and (e). Represents one type of divalent bonding group. Ar ¹ is a phenyl group and the following (h)
And one kind of monovalent bonding group selected from the group consisting of (i) and (i). R ¹ and R ² in the general formula (10) may be the same or different, they are -CH ₂ -, - CH _{2
-CH 2 -, - CH 2 -CH} 2 -CH 2 - or - (CH _{2) 4}
Represents-, and R ³ represents a carbonyl group or a divalent bonding group represented by the following (j).

[0020]

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Ar ² in the above-mentioned bonding group (e) is a divalent bonding group similar to Ar ² shown in the general formula (10), and X in (e) is a methylidene group or an isopropylidene group. , A cyclohexylidene group, —O—, —S—, one selected from the group of divalent bonding groups represented by the above (c) and the following (k), (l) and (m). Is a divalent bonding group. Further, Y in the above-mentioned bonding group (j) is one kind of divalent bonding group selected from the same divalent bonding group group as X in (e). R in the bonding group represented by the above (a), (f), (h) and the following (m) is an alkyl group having 1 to 4 carbon atoms, and R in the bonding group represented by the following (l) Ar ¹ is the same monovalent binding group as Ar ¹ in the general formula (10).

[Chemical 15]

[0022]

Embedded image In the general formula (11), n represents an integer of 5 to 5000, and m represents 0 or 1. In addition, Y is the following [a], [b],
Ar is selected from the group consisting of [f], [g] and [c] below, and one kind of divalent bonding group selected from the group consisting of [c], [d] and [e]. It represents one type of divalent linking group. Ar ′ represents a phenyl group and one kind of monovalent bonding group selected from the group consisting of [h], [i] and [j] below.

[0023]

[Chemical 17] Ar in the bonding group [e] is a divalent bonding group similar to Ar represented by the general formula (11), and X in [e] and [a], [f], [h]. And R in [j] is a bonding group similar to X and R used in the explanation of the general formula (10).

[0024]

Embedded image R ¹ in the general formula (12) is a hydrogen atom or a carbon number of 1 to 20.
R ² represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a furyl group, a pyridyl group, a nitrophenyl group, a chlorophenyl group or a methoxyphenyl group.
Then, p is an integer of 2 or more, q is an integer of 1 or more, and r is 2
It represents the above integers.

[Chemical 19] R ³ and R ⁴ in the general formula (13) may be the same or different, but these represent an alkyl group, an aryl group or an aralkyl group, and Ar ¹ and Ar ² and Ar ³ are the same or different. May be, but represents a divalent aromatic group. And s
Is an integer of 0 or more, t is an integer of 1 or more, u is an integer of 3 to 6, and v is an integer of 2 or more.

[0025]

Embedded image The general formula (14) is a repeating unit of a polymer containing a tertiary amine disclosed in JP-A-5-66598, in which k is 0 to 4, m is 0 to 5 and n is 1. -10,
p represents an integer of 0 or 1. R ₁ may be a hydrogen atom or a methyl group, and R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, but these may be an alkyl group or an alkoxy group which may be substituted, or a substituted group. Optionally an aryl group, an aryloxy group or an aralkyloxy group,
It represents either a halogen atom, an optionally substituted amino group or a hydrogen atom.

(E) Other polymers Formaldehyde condensate of nitropyrene, 6-vinyl indolo (2,3-b) quinoxaline derivative as a monomer component [a compound described in JP-A-51-73888] A compound having a structure shown in (1)], a formaldehyde condensate of 1,1-bis (4-dibenzylaminophenyl) propane, and the like.

[Chemical 21] R in the general formula (15) represents a C _{1 to} C ₄ alkyl group or alkoxy group, a nitro group, an amino group, a halogen atom, or a mono- or dialkylamino group, and n represents an integer of 0 to 3. .

The above-mentioned polymer charge-transporting substances are generally used alone, but it is also possible to use a mixture of two or more polymer charge-transporting substances. Further, among the above, particularly preferable polymer charge transport materials are the above (b) and (c).
It is the polymer exemplified in (d). An oligomer can also be used as the polymer charge transport material.

The charge-transporting substance added to the intermediate layer in the present invention may be a charge-transporting substance added to an ordinary photosensitive layer in addition to the above-described polymer charge-transporting substance. Transport materials and hole transport materials can be used.
And these may be used individually or in mixture of 2 or more types. (I) Electron transport substance: chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,
4,7-trinitro-9-fluorenone, 2,4,5,
7-tetranitro-9-fluorenone, 2,4,5,7
-Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-
An electron accepting substance such as trinitrodibenzothiophene-5,5-dioxide. (II) Hole transport material: poly-N-vinylcarbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, oxazole derivative, oxa Diazole derivative, imidazole derivative, triphenylamine derivative,
9- (p-diethylaminostyrylanthracene),
1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivative,
Thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, etc.

The charge generating substance used in the electrophotographic photoreceptor of the present invention may be an inorganic type or an organic type. And as an inorganic material, crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen,
Examples include selenium-arsenic compounds and amorphous silicon. Amorphous silicon has dangling bonds terminated with hydrogen atoms or halogen atoms,
Alternatively, those doped with a boron atom, a phosphorus atom or the like are preferable. Organic materials include phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine; azurenium salt pigments; squaric acid methine pigments; carbazole skeleton, triphenylamine skeleton, diphenylamine skeleton, dibenzothiophene skeleton, fluorenone skeleton, oxadiazole skeleton. , Azo pigment having bisstilbene skeleton, distyryl oxadiazole skeleton, azo pigment having distyryl carbazole skeleton; perylene pigment; anthraquinone pigment, polycyclic quinone pigment; quinone imine pigment; diphenylmethane pigment, triphenylmethane -Based pigments; benzoquinone-based pigments, naphthoquinone-based pigments; cyanine-based pigments, azomethine-based pigments; indigoid-based pigments;
Examples thereof include bisbenzimidazole pigments. These charge generating substances may be used alone or in combination of two or more.

The electrophotographic photosensitive member of the present invention is provided with a photosensitive layer containing a charge generating substance or the substance and a charge transporting substance on a conductive support, and a dry layer is formed thereon with or without an intermediate layer. It is a photoreceptor having a laminated protective layer. And
According to the present invention, four types of electrophotographic photoconductors having different layer constitutions are provided, which will be described with reference to the drawings as shown in FIGS. The photosensitive layer of the electrophotographic photosensitive member of the present invention may be a single layer or a multilayer, but the present invention is characterized in that at least one of the intermediate layer or the photosensitive layer contains a charge transporting substance. There is. FIG. 1 is a sectional view of an electrophotographic photoreceptor in which a photosensitive layer 2, an intermediate layer 3, and a protective layer 4 are sequentially laminated on a conductive support 1. In FIG. 2, in order to make the photosensitive layer 2 a function-separated type, a charge generating layer 21 and a charge transporting layer 22 are sequentially laminated on the conductive support 1, and the photosensitive layer is constituted by both of them. FIG. 3 is a cross-sectional view of an electrophotographic photosensitive member having the same configuration as the case. 3 and 4 are cross-sectional views of the electrophotographic photosensitive member having no intermediate layer 3. FIG. 3 corresponds to FIG. 1 and FIG. 4 corresponds to FIG.

The conductive support 1 used in the electrophotographic photosensitive member of the present invention may be the same as the conventional conductive support for electrophotographic photosensitive members. That is, any film or drum having a conductive material having a volume resistance of 10 ¹⁰ Ω or less on its surface may be used, and metals such as aluminum, nickel, chromium, nichrome, copper, silver, silver, platinum, tin oxide, indium oxide, etc. The film or drum whose surface is made conductive by vapor-depositing or sputtering the above metal oxide on a support is used. And
As the material of the support used here, plastic or paper is suitable. In addition, aluminum, aluminum alloy, nickel, stainless steel plate, or the metal
A metal tube is preferably used, which is formed into a tubular shape by a method such as I, II, extrusion or drawing, and then precisely surface-treated by a method such as cutting, superfinishing or polishing.

The charge generating layer 21 is a layer containing the charge generating substance as a main component, and a binder resin may be used to form the substance into a homogeneous thin layer. The binder resin used here includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, etc. Are preferred, and these are used alone or in admixture of two or more. The method of forming the charge generation layer is roughly classified into a vacuum thin film forming method and a casting method from a solution dispersion system. The former is a method of forming a charge generation layer mainly composed of an inorganic charge generation material, and includes a vacuum vapor deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method and the like. When the charge generating layer is provided by the latter, the charge generating substance alone or together with the binder resin is dispersed in a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone or the like to appropriately dilute the support, and then the support is prepared. It can be formed by coating on top. The coating in this case is performed by a dip coating method, a spray coating method, a bead coating method, or the like. Further, the above-mentioned dispersion liquid is produced by a dispersing / crushing machine such as a ball mill, an attritor or a sand mill. The thickness of the charge generation layer provided as described above is 0.01 to 5 μm, preferably 0.05 to 2 μm. Further, the concentration of the charge generating substance in the layer is 10% by weight or more, preferably 50% by weight or more.

The charge transport layer 22 is formed by a method in which a charge transport substance and a binder resin are dissolved or dispersed in a solvent, and this is applied and dried on the charge generation layer. Is the same as that of the charge generation layer formed by the casting method. A plasticizer and a leveling agent can be added to the layer, if necessary. As the charge transporting substance, one or a mixture of two or more selected from the polymer charge transporting substance, the electron transporting substance and the hole transporting substance may be used. It is 20% or more, preferably 40 to 100% by weight.
The binder resin added to the charge transport layer is polycarbonate (bisphenol A type, bisphenol Z type), polyester, methacrylic resin, acrylic resin,
Polyethylene, polyvinyl chloride, polyvinyl acetate, polystyrene, phenol resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral,
Examples thereof include polyvinyl formal, polyacrylate, polyacrylamide, and phenoxy resin. These binder resins may be used alone or in combination of two or more.
The thickness of the charge transport layer is 5 to 100 μm, preferably 15 to
It is 40 μm. As the plasticizer added to the layer, a general resin plasticizer such as dibutyl phthalate or dioctyl phthalate can be used as it is, and the amount thereof is 0 to 30% by weight of the binder resin, preferably 1-2
It is 0%. As the leveling agent added to the layer, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used. It is about 0 to 1% of the weight.

In the case where the photosensitive layer 2 has a single layer structure using an inorganic charge generating material, the photosensitive layer can be formed by the same material and method as the above-mentioned inorganic charge generating layer. In addition,
The layer may have a multi-layered structure containing an inorganic charge generating substance in all layers. Further, the layer is generally formed only with an inorganic charge generating substance, and it is good to contain at least 10 wt% or more, preferably 50 to 100 wt% of an inorganic charge generating substance, and its thickness is 5 ˜100 μm, preferably 20 to 50 μm. When the photosensitive layer having a single-layer structure is provided by the casting method, both the charge generating substance and the charge transporting substance are generally added in the photosensitive layer, and the charge generating substance and the charge transporting substance added here are those described above. Is used. Further, the photosensitive layer is prepared by dissolving and / or dispersing a charge-generating substance, a charge-transporting substance, a binder resin, and an additive, which is added as necessary, in a solvent, and coating and drying it on a conductive support. In the same manner as in the case of the charge transport layer described above, a plasticizer, a leveling agent, and the like can be cited as the additives to be added if necessary, and the amount of addition is the same as described above. The binder resin used here may be the same as that used for the charge transport layer, but the binder resin used for the charge transport layer and that of the charge generation layer may be mixed and used.

In the single-layer photosensitive layer formed by the casting method, the charge generating substance is generally added in an amount of 1 to 50% by weight, preferably 5 to 20% by weight, and the charge transporting substance is added in an amount of 20 to 90% by weight. Preferably 40 to 60% by weight is added. The thickness is 5 to 100 μm, preferably 10 to 50 μm. The type of solvent used for forming the layer, the method for producing the coating solution, and the coating method are the same as those for forming the charge transport layer. In addition to the above, it is also possible to form a single-layer type photosensitive layer by adding a charge-transporting substance to a eutectic complex formed from a pyrylium dye and bisphenol A-based polycarbonate. The same as when forming the transport layer.

The intermediate layer 3 is provided as necessary for the purpose of improving adhesion, preventing damage to the photosensitive layer or the charge transport layer, improving charge injection property from the photosensitive layer or the charge transport layer to the protective layer, and the like. Further, in the present invention, the intermediate layer is a charge transport material,
In particular, one of the characteristics is that it contains a high molecular charge transport material, but the addition amount is preferably the minimum amount capable of transporting charges from the viewpoint of improving adhesiveness and preventing damage to the photosensitive layer and the like. The specific amount of the charge transport substance added varies depending on the use process and the like, but is 50% by weight, preferably 10 to 30% by weight, and it is more preferable to determine the added amount by preliminary experiments. If necessary, additives such as an antioxidant and a leveling agent may be added to the layer. Since the intermediate layer 3 is formed of a binder resin containing the above-mentioned additive and the main purpose of the layer is to improve the adhesiveness and prevent damage, a resin having good adhesiveness and relatively hard is preferable as the binder resin. The above-mentioned substances are used as the charge-transporting substance and the polymer charge-transporting substance added to the layer, and the below-mentioned substances are used as the antioxidant. The intermediate layer is provided by the casting method, and the specific layer forming method is the same as when forming the charge generation layer or the charge transport layer by the casting method. The thickness of the intermediate layer is 5 μm or less, preferably 0.5 to 3 μm.

The protective layer 4 is a layer whose purpose is to protect the surface of the photoconductor, and the electrophotographic photoconductor of the present invention has a protective layer for dry film formation. That is, a protective layer made of amorphous carbon or hard carbon (JP-A-60-249155), a diamond-like carbon protective layer (JP-A-61-255352), and a high hardness insulating layer containing carbon as a main component ( JP 61-
No. 264355), a protective layer made of an amorphous hydrocarbon produced by glow discharge (JP-A-63-220166-9).
Japanese Patent Laid-Open No. 63-26).
No. 4766), a protective layer made of a film deposited by a glow discharge decomposition method (Japanese Patent Laid-Open No. 2-50166), and the like are laminated. Then, these protective layers are provided by a vacuum thin film forming method such as a glow discharge decomposition method, a plasma glow discharge method, an ion plating method and a plasma CVD method, and the thickness thereof is 0.5 to 10 μm, preferably 1 to 5 μm. is there.

The electrophotographic photosensitive member of the present invention may contain an antioxidant in order to improve the environment resistance and prevent a decrease in sensitivity and an increase in residual potential. The antioxidant may be added to any layer containing an organic substance, but it is preferably added to the layer containing a charge transporting substance. Specific examples of the antioxidant to be added include the following compounds. (1) Monophenol compound: 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole,
2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and the like. (2) Bisphenol compounds: 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,
2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-t-)
Butylphenol), 4,4'-butylidenebis (3-
Methyl-6-t-butylphenol) and the like. (3) Polymeric phenolic compound: 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris ( 3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ',
5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-
Hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, tocopherols and the like. (4) Paraphenylenediamines: N-phenyl-N '
-Isopropyl-p-phenylenediamine, N, N'-
Di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'-di-isopropyl-p-phenylenediamine, N, N'-dimethyl-N, N ′ -Di-t-butyl-p-phenylenediamine and the like.

(5) Hydroquinones: 2,5-di-t
-Octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-
Methyl hydroquinone, 2- (2-octadecenyl)-
5-methylhydroquinone and the like. (6) Organic sulfur compounds: dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like. (7) Organophosphorus compounds: triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,2)
4-dibutylphenoxy) phosphine and the like. These are compounds known as antioxidants for rubbers, plastics, fats and oils, and are commercially available compounds that can be easily obtained. The antioxidant may be added in one kind or two kinds or more selected from the above, and the addition amount is 0.1 to 100%, preferably 2 to 30% of the weight of the charge transport material.

[0040]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. The parts described below represent parts by weight.

Example 1 A coating solution for forming a photosensitive layer and a coating solution for forming an intermediate layer having the following compositions were sequentially coated and dried on an aluminum cylindrical support having a diameter of 120 mm and dried to obtain a photosensitive layer having a dry thickness of about 22 μm and a dry thickness of about 0. After forming an intermediate layer having a thickness of 0.3 μm, a protective layer having a thickness of about 2 μm was formed by the following method to prepare an electrophotographic photoreceptor of the present invention. [Composition of coating liquid for forming photosensitive layer] 2 parts of charge generating substance having the following structure

[Chemical formula 22] 10 parts of charge transport material having the following structure

[Chemical formula 23] Polycarbonate (Idemitsu Petrochemical: A2200) 10 parts Dichloromethane 180 parts

[Composition of Coating Liquid for Forming Intermediate Layer] 5 parts of polymeric charge transport material having the following structure

[Chemical formula 24] Polyester carbonate (manufactured by Mitsubishi Gas Chemical Co., Inc .: Iupilon P-100) 9 parts Tetrahydrofuran 100 parts [Method for forming protective layer] An amorphous carbon film is formed by using the same device as that disclosed in JP-A-63-2201669. It was provided by the plasma CVD method.

Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the composition of the coating solution for forming the intermediate layer was changed to the following composition. [Intermediate layer forming coating liquid composition] N, N-bis (p-tolyl) -4-aminobiphenyl 5 parts (the same charge transporting substance as the above chemical formula 23) Polyester carbonate (Mitsubishi Gas Chemical: Iupilon P-100) 9 Part Tetrahydrofuran 100 parts

Example 3 On the same support as in Example 1, a coating solution for forming a charge generating layer, a coating solution for forming a charge transport layer and a coating solution for forming an intermediate layer having the following compositions were sequentially coated and dried to give a dry thickness of about An electrophotography of the present invention was performed by forming a charge generation layer having a thickness of 0.3 μm, a charge transport layer having a dry thickness of approximately 25 μm, and an intermediate layer having a dry thickness of approximately 0.3 μm, and then forming the same protective layer as in Example 1. A photoconductor was prepared. [Coating liquid composition for forming charge generation layer] 6 parts of charge generation substance having the following structure

[Chemical 25] Polysulfone (Nissan Chemical: P-1700) 2 parts Cyclohexanone 200 parts 2-Butanone 100 parts

[Composition of coating liquid for forming charge transport layer] 9 parts of charge transport material having the following structure

[Chemical formula 26] Polycarbonate (manufactured by GE: Lexan L-141) 10 parts Dichloromethane 90 parts [Composition of coating liquid for intermediate layer formation] Polymer charge transport substance having the following structure 4 parts

[Chemical 27] Polyester (Toyobo: Byron 200) 10 parts Tetrahydrofuran 100 parts

Example 4 An electrophotographic photosensitive member was produced in the same manner as in Example 3 except that the coating composition for forming the intermediate layer was changed to the following composition. [Composition of coating liquid for intermediate layer formation] N, N-bis (p-tolyl) -1-aminopyrene 5 parts (the same charge transporting substance as the above chemical formula 26) Polyester (Toyobo: Byron 200) 10 parts Tetrahydrofuran 140 parts

Example 5 A coating solution for forming a photosensitive layer having the following composition was applied onto an aluminum cylindrical support having a diameter of 80 mm and dried to a dry thickness of about 28 μm.
After forming a photosensitive layer of m, the same protective layer as in Example 1 was formed to prepare an electrophotographic photosensitive member of the present invention. [Composition of coating liquid for forming photosensitive layer] 5 parts of charge-generating substance having the following structure

[Chemical 28] 20 parts polymer charge transport material with the following structure

[Chemical 29] 100 parts of dichloromethane

Example 6 A coating solution for forming a charge generation layer and a coating solution for forming a charge transport layer having the following compositions were successively coated and dried on the same support as used in Example 1 to give a dry thickness of about 0.2 μm. The charge generation layer and the charge transport layer having a dry thickness of about 25 μm were formed, and then the same protective layer as in Example 1 was formed to prepare the electrophotographic photoreceptor of the present invention. [Composition of coating liquid for forming charge generation layer] 5 parts of charge generation substance having the following structure

Embedded image Polyvinyl butyral (Denka Butyral # 4000 manufactured by Denki Kagaku Kogyo) 1 part Cyclohexanone 80 parts 2-butanone 30 parts

[Composition of Coating Liquid for Forming Charge Transport Layer] 10 parts of polymeric charge transport material having the following structure

[Chemical 31] 70 parts of dichloromethane

Comparative Example 1 An electrophotographic photosensitive member was produced in exactly the same manner as in Example 1 except that the polymer charge transport substance was removed from the coating liquid for forming the intermediate layer. Comparative Example 2 An electrophotographic photosensitive member was produced in exactly the same manner as in Example 3 except that the polymer charge transport substance was removed from the coating liquid for forming the intermediate layer.

Comparative Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 5 except that the composition of the photosensitive layer forming coating solution was changed to the following composition. [Coating liquid composition for forming photosensitive layer] Charge generating substance added to charge generating layer of Example 6 5 parts N, N-bis (p-tolyl) -4-methoxy-4'-aminostilbene 10 parts Polycarbonate (Bayer Co.) Made by: Macrolon 3100) 10 parts Dichloromethane 100 parts

Comparative Example 4 A charge transport layer-forming coating solution was changed to the following composition, except that
An electrophotographic photosensitive member was produced in the same manner as in Example 6. [Coating liquid composition for forming charge transport layer] 10 parts of a low molecular charge transport material having the following structure

Embedded image Polyarylate (Unitika Ltd .: U polymer U-1000) 10 parts Dichloromethane 80 parts

[Evaluation of Electrophotographic Photoreceptors of Examples and Comparative Examples] The electrophotographic photoreceptors of Examples and Comparative Examples produced as described above were electrophotographic copying devices (Ricoh Co., Ltd., which was modified to be negatively charged). Recopy FT7050) and set 5
Ten thousand running tests were performed. Table 1 shows the results of visual evaluation of the image quality of the 10th and 50,000th copied images.

[0054]

[Table 1]

From Table 1, with the electrophotographic photosensitive member of the present invention, a good copy image can be obtained even if a large amount is continuously copied.
In the electrophotographic photosensitive member of the comparative example, the image quality is remarkably deteriorated. Further, since the electrophotographic photosensitive member of the present invention is provided with the protective layer formed by the dry film forming method, there is almost no possibility that the photosensitive layer is damaged even if a large amount of copying is continuously performed. It is known that if none or the mechanical strength of the protective layer is weak, problems such as damage to the photosensitive layer occur, and the image quality significantly deteriorates.

[0056]

The electrophotographic photoreceptor of the present invention is excellent in abrasion resistance during repeated use and has a small residual potential, so that the photosensitive layer is damaged and the quality of a copied image is improved even when a large number of copies are continuously made. The electrophotographic photosensitive member is capable of continuously providing high-quality copied images for a long period of time without deterioration. Further, since the electrophotographic photosensitive member of the present invention has further high-speed response, it is possible to cope with high-speed copying and downsizing of the photosensitive member.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a cross section of an electrophotographic photosensitive member of the present invention.

FIG. 2 is a diagram showing another example of the cross section of the electrophotographic photosensitive member of the present invention, which is different from FIG.

FIG. 3 is a sectional view of the electrophotographic photosensitive member of the present invention.
It is a figure which shows another example different from.

FIG. 4 is a diagram showing another example of the cross section of the electrophotographic photosensitive member of the present invention, which is different from FIGS.

[Explanation of symbols]

1 Conductive Support 2 Photosensitive Layer 3 Intermediate Layer 4
Protective layer 21 Charge generation layer 22 Charge transport layer

Claims (5)

[Claims] 1. An electrophotographic photoreceptor having at least a photosensitive layer, an intermediate layer, and a protective layer formed by a dry film forming method on a conductive support, wherein the intermediate layer contains a charge transporting substance. An electrophotographic photoreceptor characterized by: 2. The electrophotographic photosensitive member according to claim 1, wherein at least a part of the charge transport substance contained in the intermediate layer is a polymer charge transport substance. 3. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer comprises a charge generating layer and a charge transporting layer. 4. An electrophotographic photoreceptor having at least a photosensitive layer on a conductive support and a protective layer formed by a dry film forming method, wherein the photosensitive layer contains a polymer charge transporting substance. Characteristic electrophotographic photoreceptor. 5. The electrophotographic photoreceptor according to claim 4, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer, and the charge transport layer contains a polymer charge transport substance.