JPH07175249A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor having high sensitivity and high durability by incorporating an anthraquinone compound into a primary coat layer. CONSTITUTION:In the function separating electrophotographic photoreceptor formed by successively laminating a charge generation layer (CGL) and a charge transport layer (CTL) containing a donor type compound having positive hole transporability on an electrically conductive substrate, the primary coat layer containing the anthraquinone based compound is provided between the electrically conducive substrate and the CGL. An electron transport material expressed by a formula 1 or II is preferably used as the anthraquinone compound. In the formula, each of R1 and R2 represents alkyl group, aromatic group or heterocyclic group and each of X and Y represents =O, =N(CN) or the like.

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 a copying machine, a printer or the like using an electrophotographic process.

[0002]

2. Description of the Related Art Since the electrophotographic process uses the visualization of a latent image by electrostatic force as a basic principle, the electrophotographic photosensitive member used in the process has good chargeability and rapid surface irradiation by light irradiation. Potential decay is required.
The properties required for these processes are reduced to a high dark resistance which is a specific physical property value, a good quantum efficiency of charge carrier generation, and a high charge mobility.

In order to satisfy these physical property values, a photoconductor composed of an inorganic compound such as selenium, selenium-tellurium alloy, arsenic selenium, etc. has been adopted and has been used in many copying machines. However, these materials have drawbacks that they are highly toxic, are difficult to handle because they are used in an amorphous state, and have a high cost because they require a film thickness of several tens of μm by a vapor deposition method. It cannot be said that it can be said that it fully satisfies the necessary functions of.

In order to improve these drawbacks, electrophotographic photoconductors (OPC) using organic materials have been actively developed and put into practical use. Most of the practically used OPCs are function-separated type photoconductors having a structure in which a layer having a charge generation function (CGL) and a layer having a charge transport function (CTL) are laminated on a conductive substrate, and separate the functions. As a result, the range of choice of materials is expanded, and the electrophotographic sensitivity,
The characteristics such as repeatability and mechanical strength are improved.
It has come to be installed in many printers and the like. However, when a photosensitive layer is directly provided on a conductive substrate in such an OPC, defects of the conductive substrate, that is, surface defects such as scratches, impurities, and corrosive substances are directly reflected in the image,
It often causes abnormal images such as black spots and white spots. In particular, the CGL of the function-separated type photoconductor is usually several μm.
It is necessary to form the following thin film, and defects on the surface of the substrate are easily picked up, defects in the coating film are likely to occur, and productivity is reduced. In many cases, the adhesiveness between the conductive substrate and the photosensitive layer is poor, and the entire surface may be peeled off from a scratch on the small photosensitive layer.

In order to prevent them, many photoreceptors have an undercoat layer as a barrier layer or an adhesive layer between the conductive substrate and the photosensitive layer. As the undercoat layer, an insulating polymer material is mainly provided as a thin film with a submicron thickness, but since it is insulating, it has the fatal drawback of causing a decrease in sensitivity and an increase in residual potential. Have Various methods have been proposed for the purpose of preventing these. One is a method of dispersing an inorganic conductive filler in the undercoat layer, one is a method of incorporating an ion conductive polymer in the undercoat layer, and another is a method of undercoating an electron transporting substance having an acceptor property. It is a method of including in a layer. Titanium oxide and tin oxide are used as the inorganic conductive filler (Japanese Patent Publication No. 63-19).
No. 869), it is necessary to disperse them in the coating liquid for the undercoat layer, which involves technical difficulties in adjusting the dispersion liquid and pot life. As the ion-conductive polymer, for example, polymers such as soluble nylon and polyamide are used (JP-A-52-25638, JP-A-58-30757).
No.) has not yet solved the problem due to its low conductivity. Further, the third method is to add an electron-transporting substance having an acceptor property to these, and for example, an acceptor compound such as trinitrofluorenone or tetracyanoquinodimethane is used. There is a problem with compatibility. As described above, when the undercoat layer is provided, there remains an important problem that the sensitivity and the durability are lowered, and the development of a high-performance electrophotographic photoreceptor that improves these is strongly demanded in the technical field. It is the actual situation that has been done.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems by providing a specific compound having an electron transporting property in an electrophotographic photoreceptor having an undercoat layer which hardly causes image defects. The purpose of the present invention is to provide a high-sensitivity and high-durability electrophotographic photoreceptor by incorporating it in the undercoat layer.

[0007]

As a result of intensive studies to solve the above problems, the present inventors have found that an anthraquinone compound, preferably a compound represented by the following general formula (I) or (II), is present between the conductive substrate and the photosensitive layer. The present invention was found to be able to solve the above problems by providing an undercoat layer containing a compound represented by the above, and has reached the present invention.

[Chemical 1]

[Chemical 2] (In the formula, R ₁ and R ₂ represent an alkyl group, an aromatic group or a heterocyclic group. R ₁ and R ₂ may form a ring with each other. X,
Y is = O, = N (CN) , = N- (C 6 H 4) represents the (R ₃₎ n, or = C (A) (B) . Here, R ₃ is a hydrogen atom, a halogen atom, an alkyl group, an aromatic group, an acyl group,
It represents an alkoxy group, an ester group, an amide group, a cyano group, a nitro group, a sulfone group or a sulfonamide group. n represents an integer of 1 to 3. A and B represent a hydrogen atom, a halogen atom, a cyano group, an R ₄ -substituted phenyl group, and —COOR ₅ groups. Here, R ₄ represents a hydrogen atom, a halogen atom, an alkyl group, an aromatic group, an acyl group, an alkoxy group, an ester group, an amide group, a cyano group, a nitro group, a sulfone group or a sulfonamide group. R ₅ represents an alkyl group or an aromatic group. That is, according to the present invention, a function separation type structure in which a charge generation layer (CGL) and a charge transport layer (CTL) containing a donor compound having a hole transport ability are sequentially laminated on a conductive substrate. Provided is an electrophotographic photoreceptor, wherein an undercoat layer containing an anthraquinone compound is provided between the conductive substrate and the CGL.

R in the above general formulas (I) and (II) of the present invention
_{In 1} and R ₂ , the alkyl group is a methyl group, an alkyl group such as t-butyl group, a cycloalkyl group such as a cyclohexyl group and a cyclopentyl group, a trifluormethyl group, a bromooctyl group, 2,2,3,4, Halogen-substituted alkyl groups such as 4,4-hexafluorobutyl group and 2,2-difluoro-2-trifluoromethyl-ethyl group, and alkoxy-substituted alkyl groups such as 2-methoxyethyl group and 2,2-diethoxyethyl group. Group, 4-hexyloxycarbonylhexyl group, alkoxycarbonylalkyl group such as butoxycarbonylmethyl group, benzyl group, cyanoalkyl group, nitroalkyl group and the like.

The aromatic group includes aromatic groups such as phenyl group, pyrene group and phenanthrene group, halogen-substituted aromatic groups such as 4-chlorophenyl group, 1-bromonaphthyl group and 2-trifluoromethylanthracene group, Alkoxy-substituted aromatic groups such as 4-butoxyphenyl group and 2,6-dihexaoxynaphthyl group, 3-methoxycarbonylphenyl group, alkoxycarbonyl aromatic groups such as 4-butoxycarbonylnaphthyl group and 4-acetylphenyl group Represents an acyl-substituted aromatic group, a phenyl-substituted aromatic group such as diphenyl, and the like.

The heterocyclic group means a pyrrole group, a carbazole group, an indole group, a pyridine group, a morpholine group,
It represents a thiazine group, a piperidine group, a pyrrolidine group, an imidazole group or the like.

In the general formulas (I) and (II) of the present invention, in R ₃ and R ₄ , the halogen atom is a halogen atom such as fluorine, bromine and iodine, the alkyl group is a methyl group and t-. Alkyl group such as butyl group, cycloalkyl group such as cyclohexyl group, cyclopentyl group,
Trifluoromethyl group, bromooctyl group, 2,2
Halogen-substituted alkyl groups such as 3,4,4,4-hexafluorobutyl group and 2,2-difluoro-2-trifluoromethyl-ethyl group, 2-methoxyethyl group, 2,2
-Alkoxy-substituted alkyl group such as diethoxyethyl group, 4-hexyloxycarbonylhexyl group, alkoxycarbonylalkyl group such as butoxycarbonylmethyl group, benzyl group, cyanoalkyl group, nitroalkyl group and the like.

The aromatic group includes aromatic groups such as phenyl group, pyrene group and phenanthrene group, halogen-substituted aromatic groups such as 4-chlorophenyl group, 1-bromonaphthyl group and 2-trifluoromethylanthracene group, Alkoxy-substituted aromatic groups such as 4-butoxyphenyl group and 2,6-dihexaoxynaphthyl group, 3-methoxycarbonylphenyl group, alkoxycarbonyl aromatic groups such as 4-butoxycarbonylnaphthyl group and 4-acetylphenyl group Represents an acyl-substituted aromatic group, a phenyl-substituted aromatic group such as diphenyl, and the like.

The acyl group refers to an acetyl group, an octylcarbonyl group, etc., the alkoxyl group refers to a methoxy group, an ethoxy group, a benzyloxy group, etc., and the ester group refers to a butoxycarbonyl group, a phenoxycarbonyl group, Acetoxyl group and the like are referred to as N, N- and amide groups.
A ditolylamide group, an N-methyl-N-phenylamide group, an N-butoxycarbonylamino group, etc., and a sulfonamide group are N, N-dihexylsulfonamide group, N
Represents a methoxysulfonylamino group and the like.

In R ₅ , the alkyl group is an alkyl group such as a methyl group or a t-butyl group, a cycloalkyl group such as a cyclohexyl group or a cyclopentyl group, a trifluormethyl group, a bromooctyl group, 2,2,2. Three
Halogen-substituted alkyl groups such as 4,4,4-hexafluorobutyl group and 2,2-difluoro-2-trifluoromethyl-ethyl group, alkoxy substitution such as 2-methoxyethyl group and 2,2-diethoxyethyl group An alkyl group of
4-hexyloxycarbonylhexyl group, an alkoxycarbonylalkyl group such as butoxycarbonylmethyl group, a benzyl group, a cyanoalkyl group, a nitroalkyl group and the like, the aromatic group, a phenyl group, a pyrene group,
Aromatic group such as phenanthrene group, 4-chlorophenyl group, 1-bromonaphthyl group, halogen-substituted aromatic group such as 2-trifluoromethylanthracene group, 4-butoxyphenyl group, 2,6-dihexaoxynaphthyl group, etc. Alkoxy substituted aromatic groups, 3-methoxycarbonylphenyl groups, 4-butoxycarbonylnaphthyl groups and other alkoxycarbonyl aromatic groups, 4-acetylphenyl groups and other acyl substituted aromatic groups, diphenyl and other phenyl substituted aromatic groups, etc. Represents

Specific examples of the anthraquinone compounds represented by the general formulas (I) and (II) which are preferably used in the present invention are shown below.

The electrophotographic photoreceptor of the present invention has high sensitivity and excellent durability because it contains an anthraquinone compound in the undercoat layer.

[0017]

[Table 1- (1)]

[0018]

[Table 1- (2)]

[0019]

[Table 2- (1)]

[0020]

[Table 2- (2)]

[0021]

[Table 2- (2)]

The anthraquinone compound represented by the general formula (I) or (II) has an electron transporting ability and is soluble in many solvents. Examples of such a solvent include aromatic solvents such as benzene, toluene, xylene and chlorobenzene, halogen solvents such as dichloromethane, 1,2-dichloroethane and chloroform, methyl acetate, ethyl acetate, propyl acetate and ethyl formate. Ester solvents, acetone, methyl ethyl ketone, ketone solvents such as cyclohexanone, diethyl ether, dioxane, ether solvents such as tetrahydrofuran, alcohol solvents such as methanol, ethanol, isopropanol, and dimethylformamide, dimethylacetamide, dimethyl sulfoxide and the like. To be

The electrophotographic photoreceptor of the present invention is preferably provided with an undercoat layer containing an anthraquinone compound represented by the general formula (I) or (II) in a binder resin on a conductive substrate. Then, the charge generation layer and the charge transport layer are sequentially laminated to produce the layer.

As the conductive substrate used in the present invention,
Metal plates such as aluminum, nickel, copper, stainless steel,
Examples thereof include a metal drum or a metal foil, a plastic film coated with a thin film of aluminum, tin oxide, copper iodide, or the like, or glass. The binder resin used in the undercoat layer of the present invention is not particularly limited, and examples thereof include polyethylene resin, polypropylene resin, acrylic resin, polystyrene resin, vinyl chloride resin, vinyl acetate resin, polycarbonate resin, polyarylate resin. , Phenoxy resin, polyurethane resin, butyral resin, polyamide resin, vinylidene fluoride resin, silicone resin, fibrin resin, cyanoethyl pullulan, phenol resin, melamine resin, alkyd resin, epoxy resin, etc. Examples thereof include resins, polycondensation resins, and copolymer resins containing two or more of these repeating units, and these can be used alone or in combination of two or more.

The amount of the compound represented by the general formula (I) or (II) used is 1 to 50% by weight based on these binder resins.
It is preferably 2 to 30% by weight. If it is 1% by weight or less, the effect is small, and if it is 50% by weight or more, the charging property is deteriorated. The thickness of the undercoat layer is preferably 0.1 to 2.0 μm.

The charge generation layer of the present invention can be provided by dispersing the charge generation substance in a binder resin and coating or vapor depositing it. As the charge generating substance, bisazo dye, trisazo dye, phthalocyanine dye, quinacridone dye, perylene dye, polycyclic quinone dye, indigo dye, cyanine dye, pyrylium dye, bisbenzimidazole dye, indanthrone dye, triarylmethane dye,
Thiazine dye, oxodine dye, squarylium dye,
Organic compounds such as anthraquinone dyes and xanthene dyes, inorganic compounds such as selenium, selenium alloys, cadmium sulfide, cadmium sulfide selenide, and amorphous silicon can be mentioned. When used with a binder resin, the charge generating substance 10
The binder resin is 10 to 400 parts by weight, preferably 25 to 100 parts by weight, based on 0 parts by weight. The thickness of the charge generation layer is 0.05 to 10 μm, preferably 0.1 to 2 μm.
Is.

The charge transport layer of the present invention comprises at least a hole transport material and a binder resin, and if necessary, an additive can be added. As the hole-transporting substance, a compound having a triphenylamine moiety in the molecule, a hydrazone compound, a pyrazoline compound, a triphenylmethane compound,
Donor compounds such as oxazole compounds, oxadiazole compounds, carbazole group-containing compounds, styryl compounds, butadiene compounds, polysilane compounds, poly-N-vinylcarbazole, and pyrene-formalin condensates can be used alone or in combination. . The structure of the charge transport layer is 25 to 400 parts by weight, preferably 50 to 200 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is 5 to 60 μm, preferably 10 to 30 μm. Further, examples of the additives used as necessary include antifoaming agents, antioxidants, adhesion aids, plasticizers and the like. As the binder resin for the charge generation layer and the charge transport layer, the resin used in the undercoat layer can be used.

The electrophotographic photoreceptor of the present invention can be produced by a known coating method, for example, a dipping coater, a calendar coater, a kiss coater, a gravure coater, a blade coater, a spray coater or a spin coater.

[0029]

EXAMPLES The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereby.

Example 1 Exemplified Compound No. 11 g, nylon resin (CM800
0 Toray Co., Ltd. 5 g was dissolved in ethyl alcohol 94 g, and aluminum was evaporated to a thickness of 1000 Å 75
It was coated on a polyester film having a thickness of μm with a doctor blade, and an undercoat layer having a film thickness after drying of 0.5 μm was provided. Next, 1 g of the bisazo pigment having the following structural formula was added to 5% by weight of butyral resin (S-REC BL-S Sekisui Chemical Co., Ltd.).
Ball-milling with 10 g of tetrahydrofuran solution and 9 g of tetrahydrofuran, adding tetrahydrofuran after milling, diluting to 2% by weight, and coating with a doctor blade on the undercoat layer to form a charge generation layer having a thickness of 1.0 μm after drying. Provided. Next, 6 g of a triphenylamine compound, which is a hole-transporting substance having the following structural formula, 9 g of polycarbonate Z (manufactured by Teijin Chemicals Ltd.), silicone oil (KF
50 manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 85 g of tetrahydrofuran, and the solution was applied on the charge generation layer, and a charge transport layer having a thickness of 20 μm after drying was provided. An electrophotographic photoreceptor was produced in which a generation layer and a charge transport layer were sequentially laminated.

[Chemical 2]

[Chemical 3]

Example 2 Exemplified Compound No. which is a compound contained in the undercoat layer. 1 is exemplified compound No. 1. An electrophotographic photoreceptor was produced under the same conditions as in Example 1 except that the number of 10 was changed.

Example 3 Exemplified Compound No. which is a compound to be contained in the undercoat layer. 1 is exemplified compound No. 1. Instead of 22, X-type metal-free phthalocyanine (Fastogen Blue) is used as a charge generating substance.
An electrophotographic photoreceptor was prepared under the same conditions as in Example 1, except that 8120BS Dainippon Ink Co., Ltd. was used.

Comparative Example An electrophotographic photoreceptor was prepared under the same conditions as in Example 1 except that the subbing layer was not provided.

The electrophotographic photoconductor thus prepared was used as an electrostatic copying paper tester (SP-42) manufactured by Kawaguchi Electric Co., Ltd.
8), corona discharge was performed at -6 KV for 20 seconds to charge, dark decay was performed for 20 seconds, and then tungsten light was applied for 3 seconds so that the illuminance on the surface of the photoreceptor was 20 lux.
Irradiate for 0 seconds. The surface potential Vs (V) after being charged for 20 seconds, the surface potential Vo (V) after dark decay for 20 seconds, and the exposure amount E1 required for Vo to be 1/10 were measured under the above conditions continuously 500 times. The surface potential V30 (V) after exposure for / 10 (lux seconds) and 30 seconds was measured. The measurement results are shown in Table 3.

[0035]

[Table 3]

[0036]

The electrophotographic photoreceptor of the present invention has high sensitivity and high durability because the undercoat layer contains an anthraquinone compound.

Claims (2)

[Claims] 1. A charge generation layer (CGL) on a conductive substrate,
In a function-separated type electrophotographic photosensitive member formed by sequentially stacking a charge transport layer (CTL) containing a donor compound having a hole transport ability, an anthraquinone compound is provided between the conductive substrate and the CGL. An electrophotographic photoreceptor comprising an undercoat layer containing the same. 2. The electrophotographic photoreceptor according to claim 1, wherein the anthraquinone compound is an electron transporting material represented by the following general formula (I) or (II). [Chemical 1] [Chemical 2] (In the formula, R ₁ and R ₂ represent an alkyl group, an aromatic group or a heterocyclic group. R ₁ and R ₂ may form a ring with each other. X,
Y is = O, = N (CN) , = N- (C 6 H 4) represents the (R ₃₎ n, or = C (A) (B) . Here, R ₃ is a hydrogen atom, a halogen atom, an alkyl group, an aromatic group, an acyl group,
It represents an alkoxy group, an ester group, an amide group, a cyano group, a nitro group, a sulfone group or a sulfonamide group. n represents an integer of 1 to 3. A and B represent a hydrogen atom, a halogen atom, a cyano group, an R ₄ -substituted phenyl group, and —COOR ₅ groups. Here, R ₄ represents a hydrogen atom, a halogen atom, an alkyl group, an aromatic group, an acyl group, an alkoxy group, an ester group, an amide group, a cyano group, a nitro group, a sulfone group or a sulfonamide group. R ₅ represents an alkyl group or an aromatic group. )