JPH07199509A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain a functionally separated electrophotographic photoreceptor high in sensitivity and durability by forming an undercoat layer containing a fluorene type compound between a conductive substrate and a charge generating layer. CONSTITUTION:The functionally separated electrophotographic photoreceptor is formed by successively laminating the undercoat layer containing the fluorene type compound, the charge generating layer, and a positive hole transfer layer, and the electron transfer material to be added into the undercoat layer is, preferably, the fluorene type compound represented by the formula in which R1 is a substituted or unsubstituted aromatic group, an optionally substituted heterocyclic group or alkoxycarbonyl; and each of x and y is 0, 1, 2, 3, or 4, but 1<=x+y<=4. The conductive substrate is embodied by a plate or drum or foil of a metal like aluminum or nickel, and a plastic film and glass coated with a thin film of aluminum or tin oxide or the like, and so forth.

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 problems in the conventional electrophotographic photoreceptor and to provide a function-separated electrophotographic photoreceptor having high sensitivity and high durability. To do.

[0007]

As a result of intensive studies to solve the above problems, the inventors of the present invention provided an undercoat layer containing a specific fluorene compound between a conductive substrate and a photosensitive layer. The inventors have found that the above problems can be solved by the present invention and have reached the present invention. That is, according to the present invention, the function-separated electron is formed by sequentially stacking a charge generation layer (CGL) and a charge transport layer (CTL) containing a donor compound having a hole transport ability on a conductive substrate. Provided is an electrophotographic photoreceptor, which comprises an undercoat layer containing a fluorene compound between the conductive substrate and the CGL.

Further, according to the present invention, there is provided an electrophotographic photosensitive member characterized in that the electron transporting material contained in the undercoat layer is a fluorene compound represented by the following general formula 1. It

[Chemical 1] (In the formula, R ₁ represents a substituted or unsubstituted aromatic group, a substituted or unsubstituted heterocyclic group, or an alkoxycarbonyl group, and x and y represent integers of 0, 1, 2, 3 or 4. However, 1 ≦ x + y ≦ 4.)

Further, according to the present invention, there is provided an electrophotographic photoreceptor, wherein the electron transporting material contained in the undercoat layer is a fluorene compound represented by the following general formula 2. It

[Chemical 2] (In the formula, R ₁ represents an alkyl group. However, R ₁ may combine with each other to form a ring. Further, n represents an integer of 1, 2, 3 or 4.)

Further, according to the present invention, there is provided an electrophotographic photoconductor characterized in that the electron transporting material contained in the undercoat layer is a fluorene compound represented by the following general formula 3. It

[Chemical 3] (In the formula, R ₁ , R ₂ and R ₃ are a hydrogen atom, a substituted or unsubstituted alkyl group, an alkyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted sulfonyl group. Represents a group, a substituted or unsubstituted sulfonamide group, a substituted or unsubstituted carbamoyl group, a halogen atom, a cyano group, a nitro group, may form a R ₁ ring, and X represents O or S, l, m, and n represent the integers of 1 to 4.)

In the electrophotographic photoreceptor of the present invention, typical examples of the fluorene compound contained in the undercoat layer are shown below, but the invention is not limited thereto.

Specific examples of the compound represented by the general formula 1 include those shown in Table 1 below.

[0013]

[Table 1- (1)]

[0014]

[Table 1- (2)]

[0015]

[Table 1- (3)]

[0016]

[Table 1- (4)]

[0017]

[Table 1- (5)]

[0018]

[Table 1- (6)]

[0019]

[Table 1- (7)]

[0020]

[Table 1- (8)]

[0021]

[Table 1- (9)]

[0022]

[Table 1- (10)]

[0023]

[Table 1- (11)]

[0024]

[Table 1- (12)]

[0025]

[Table 1- (13)]

[0026]

[Table 1- (14)]

Further, specific examples of the fluorene compound represented by the general formula 2 include those shown in Table 2 below.

[0028]

[Table 2- (1)]

[0029]

[Table 2- (2)]

Further, specific examples of the fluorene compound represented by the general formula 3 include those shown in Table 3 below.

[0031]

[Table 3- (1)]

[0032]

[Table 3- (2)]

[0033]

[Table 3- (3)]

[0034]

[Table 3- (4)]

[0035]

[Table 3- (5)]

[0036]

[Table 3- (6)]

[0037]

[Table 3- (7)]

[0038]

[Table 3- (8)]

[0039]

[Table 3- (9)]

[0040]

[Table 3- (10)]

[0041]

[Table 3- (11)]

[0042]

[Table 3- (12)]

[0043]

[Table 3- (13)]

[0044]

[Table 3- (14)]

[0045]

[Table 3- (15)]

[0046]

[Table 3- (16)]

[0047]

[Table 3- (17)]

[0048]

[Table 3- (18)]

[0049]

[Table 3- (19)]

[0050]

[Table 3- (20)]

[0051]

[Table 3- (21)]

[0052]

[Table 3- (22)]

[0053]

[Table 3- (23)]

[0054]

[Table 3- (24)]

[0055]

[Table 3- (25)]

[0056]

[Table 3- (26)]

[0057]

[Table 3- (27)]

[0058]

[Table 3- (28)]

[0059]

[Table 3- (29)]

[0060]

[Table 3- (30)]

[0061]

[Table 3- (31)]

[0062]

[Table 3- (32)]

[0063]

[Table 3- (33)]

The fluorene compounds represented by the general formulas 1 to 3 have an electron transporting ability and are soluble in many solvents. Examples of such a solvent include aromatic solvents such as benzene, toluene, xylene, and chlorobenzene,
Halogen-based solvents such as dichloromethane, 1,2-dichloroethane and chloroform, ester-based solvents such as methyl acetate, ethyl acetate, propyl acetate and ethyl formate, acetone,
Examples thereof include ketone type solvents such as methyl ethyl ketone and cyclohexanone, ether type solvents such as diethyl ether, dioxane and tetrahydrofuran, alcohol type solvents such as methanol, ethanol and isopropanol, and dimethylformamide, dimethylacetamide and dimethyl sulfoxide.

The electrophotographic photoreceptor of the present invention is preferably provided with an undercoat layer containing a fluorene compound represented by the general formulas 1 to 3 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 compounds represented by the general formulas 1 to 3 used is 1 to 50% by weight, preferably 2 to 30% by weight based on these binder resins. 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 generating layer of the present invention can be provided by dispersing the charge generating substance in a binder resin and coating or vapor depositing. 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 an additive can be added if necessary. 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, a spin coater or the like.

[0071]

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. (1) -11 g, nylon resin (C
M8000 Toray Co., Ltd.) 5 g ethyl alcohol 9
It was dissolved in 4 g, and aluminum was vapor-deposited on a polyester film having a thickness of 1000 .mu.m and having a thickness of 75 .mu.m to be coated with a doctor blade. Next, 1 g of the bisazo pigment represented by the following structural formula 4 was added to butyral resin (S-REC BL-S Sekisui Chemical Co., Ltd.).
Ball milling with 10 g of 5% by weight tetrahydrofuran solution and 9 g of tetrahydrofuran, and after milling, tetrahydrofuran is added to dilute to 2% by weight,
The charge generation layer was applied onto the undercoat layer with a doctor blade and had a thickness of 1.0 μm after drying. Next, a triphenylamine compound 6 which is a hole transporting substance represented by the following structural formula 5
g, Polycarbonate Z (manufactured by Teijin Chemicals Ltd.) 9 g, Silicon oil (KF50 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.00
9 g of tetrahydrofuran was dissolved in 85 g of tetrahydrofuran and applied on the charge generation layer to provide a charge transport layer having a thickness of 20 μm after drying, and an undercoat layer, a charge generation layer and a charge transport layer were sequentially laminated on a conductive substrate. An electrophotographic photoreceptor was produced.

[Chemical 4]

[Chemical 5]

Example 2 Exemplified Compound No. which is a compound contained in the undercoat layer.
An electrophotographic photoreceptor was prepared under the same conditions as in Example 1 except that (1) -1 was replaced with Exemplified Compound (1) -4.

Example 3 Exemplified compound No. contained in the undercoat layer (1) -1 is exemplified compound No. (1) X instead of -7 as a charge generating substance
Type Metal-free Phthalocyanine (FastogenBlue)
An electrophotographic photoreceptor was prepared under the same conditions as in Example 1, except that 8120BS Dainippon Ink Co., Ltd. was used.

Comparative Example 1 An electrophotographic photoreceptor was prepared under the same conditions as in Example 1 except that the undercoat 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 4.

[0077]

[Table 4]

Example 4 Exemplified Compound No. 3- (1) 1 g, nylon resin (C
M8000 Toray Co., Ltd.) 5 g ethyl alcohol 9
It was dissolved in 4 g, and aluminum was vapor-deposited on a polyester film having a thickness of 1000 .mu.m and having a thickness of 75 .mu.m to be coated with a doctor blade. Next, 1 g of the bisazo pigment represented by the above structural formula 4 was added to butyral resin (S-REC BL-S Sekisui Chemical Co., Ltd.).
Ball milling with 10 g of 5% by weight tetrahydrofuran solution and 9 g of tetrahydrofuran, and after milling, tetrahydrofuran is added to dilute to 2% by weight,
The charge generation layer was applied onto the undercoat layer with a doctor blade and had a thickness of 1.0 μm after drying. Next, the triphenylamine compound 6 which is the hole transporting substance represented by the structural formula 5 above.
g, Polycarbonate Z (manufactured by Teijin Chemicals Ltd.) 9 g, Silicon oil (KF50 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.00
9 g of tetrahydrofuran was dissolved in 85 g of tetrahydrofuran and applied on the charge generation layer to provide a charge transport layer having a thickness of 20 μm after drying, and an undercoat layer, a charge generation layer and a charge transport layer were sequentially laminated on a conductive substrate. An electrophotographic photoreceptor was produced.

Example 5 Exemplified Compound No. which is a compound to be contained in the undercoat layer. 3-
An electrophotographic photoreceptor was prepared under the same conditions as in Example 4, except that (1) was replaced with Exemplified Compound 3- (2).

Example 6 Exemplified Compound No. to be contained in the undercoat layer 3- (1) as exemplified compound No. 3- Instead of (3), X is used as the charge generating substance.
Type Metal-free Phthalocyanine (FastogenBlue)
An electrophotographic photoreceptor was prepared under the same conditions as in Example 4, except that 8120BS Dainippon Ink Co., Ltd. was used.

Comparative Example 2 An electrophotographic photoreceptor was prepared under the same conditions as in Example 4 except that the undercoat 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 5.

[0083]

[Table 5]

[0084]

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

Claims (4)

[Claims] 1. A function-separated type electrophotographic photosensitive member comprising a charge generation layer (CGL) and a charge transport layer (CTL) containing a donor compound having a hole transport ability, which are sequentially laminated on a conductive substrate. In the body, an electrophotographic photoreceptor is provided with an undercoat layer containing a fluorene compound between the conductive substrate and the CGL. 2. The electrophotographic photosensitive member according to claim 1, wherein the fluorene compound contained in the undercoat layer is an electron transporting substance represented by the following general formula 1. [Chemical 1] (In the formula, R ₁ represents a substituted or unsubstituted aromatic group, a substituted or unsubstituted heterocyclic group, or an alkoxycarbonyl group, and x and y represent integers of 0, 1, 2, 3 or 4. However, 1 ≦ x + y ≦ 4.) 3. The electrophotographic photosensitive member according to claim 1, wherein the fluorene compound contained in the undercoat layer is an electron transporting substance represented by the following general formula 2. [Chemical 2] (In the formula, R ₁ represents an alkyl group. However, R ₁ may combine with each other to form a ring. Further, n represents an integer of 1, 2, 3 or 4.) 4. The electrophotographic photoconductor according to claim 1, wherein the fluorene compound contained in the undercoat layer is an electron transporting material represented by the following general formula 3. [Chemical 3] (In the formula, R ₁ , R ₂ and R ₃ are a hydrogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted sulfonyl group. Represents a group, a substituted or unsubstituted sulfonamide group, a substituted or unsubstituted carbamoyl group, a halogen atom, a cyano group, a nitro group, may form a R ₁ ring, and X represents O or S, l, m, and n represent the integers of 1 to 4.)