JPH0659471A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body maintaining high strength of the coating film, having excellent wear resistance, not causing the sticking of foreign matter such as toner filming and also having excellent electrical characteristics and image quality characteristics. CONSTITUTION:When at least a photosensitive layer is formed on an electric conductive substrate to obtain an electrophotographic sensitive body, polycarbonate resin consisting of repeating structural units represented by formula I and polycarbonate resin having a lower mol.wt. than the above-mentioned polycarbonate resin and consisting of repeating structural units represented by formula II are used as bonding resins in the photosensitive layer. in the formula II, each of X1 and X2 is H or alkyl.

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, and more particularly to an electrophotographic photosensitive member excellent in electrophotographic characteristics and durability.

[0002]

2. Description of the Related Art In recent years, electrophotographic technology has been widely applied in the fields of copying machines, laser beam printers and the like because it has the advantages of high speed and high printing quality. As electrophotographic photoreceptors used in these electrophotographic techniques, those using inorganic photoconductive materials such as selenium, selenium-tellurium alloys, selenium-arsenic alloys, and cadmium sulfide have been widely known.

On the other hand, as compared with electrophotographic photoreceptors using these inorganic photoconductive materials, research on electrophotographic photoreceptors using organic photoconductive materials, which are inexpensive and have excellent advantages in terms of manufacturability and disposal, has also been conducted. It is becoming more active. Among them, the function-separated organic laminate type photoreceptor in which a charge generation layer that generates a charge upon exposure and a charge transport layer that transports a charge is laminated is preferable in terms of electrophotographic characteristics such as sensitivity, chargeability and repeated stability thereof. Since it is excellent, various proposals have been made and put to practical use.

Regarding these organic laminated type photoreceptors, those having sufficient performance have been developed with respect to the above-mentioned electrophotographic characteristics. However, since the photosensitive layer is composed of an organic material, a mechanical external force is applied. Therefore, there is a problem that the surface of the photoconductor is worn or scratched by contact with toner, developer, paper, cleaning member, etc. Therefore, there is a problem that an image quality defect occurs. Furthermore, problems such as image deletion in a high humidity environment caused by low-resistance substances such as ozone and nitrogen oxides generated by corona discharge and paper dust generated by copy paper adhere to the surface of the photoconductor and accumulate Yes, it significantly limits the life of the photoconductor. Further, with the colorization and speeding up of copying machines, printers, etc., the process is becoming more complicated and the stress is increasing. From these points as well, it is required to improve the durability of the electrophotographic photoreceptor. In order to solve these problems, various measures have been studied in the past, and, for example, those using polymethylmethacrylate resin, polyester resin, polycarbonate resin, etc. as a binder resin for the photoreceptor surface layer have been proposed. ing. (JP-A-6
0-172044, 62-247374, 63-148263, and JP-A-2-2544.
(Gazette No. 64)

[0005]

However, when the conventionally proposed resin is used as the binder resin for the photosensitive layer, an electrophotographic photoreceptor having relatively good durability can be obtained, but it is not yet satisfactory. . That is, the mechanical strength of the coating film formed by using these resins is not always sufficient, and when repeatedly used in a copying machine for a long time, the surface of the photosensitive layer is abraded and Since the film thickness of the layer is reduced and the sensitivity is lowered, fog occurs in the copy, the charging potential is lowered, and the copy density is lowered. Further, there is a problem that an image quality defect occurs due to a scratch generated on the surface of the photosensitive layer or a foreign substance such as toner filming. Furthermore, when the photosensitive layer has a charge transport layer composed of a charge transport material and a binder resin, the compatibility between the binder resin and the charge transport material becomes important. It is known that materials crystallize and have a significant adverse effect on electrical and image quality characteristics. Therefore, the binder resin is also required to be excellent in compatibility with the charge transport material.

Therefore, the present invention has been made in order to solve the above problems in the prior art. That is, an object of the present invention is to maintain high coating film strength, have excellent abrasion resistance, and prevent foreign matter such as toner filming from adhering to the electrophotographic image having excellent electrical and image quality characteristics. To provide a photoconductor.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above object can be achieved by using a specific resin in combination as a binder resin for a photosensitive layer. The present invention has been completed. That is, the electrophotographic photoreceptor of the present invention is one in which at least a photosensitive layer is provided on a conductive support, and the photosensitive layer is
Containing, as the binder resin, a polycarbonate resin comprising a repeating structural unit represented by the following structural formula (I) and a polycarbonate resin comprising a repeating structural unit represented by the following structural formula (II) having a lower molecular weight than the polycarbonate resin. It is characterized by being done.

[Chemical 2] (In the formula, X ₁ and X ₂ each represent a hydrogen atom or an alkyl group.)

The present invention will be described in detail below. The electrophotographic photoreceptor of the present invention comprises at least a photosensitive layer on a conductive support. Examples of the conductive support include metals such as aluminum, nickel, chromium, and stainless steel, and aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide,
Examples thereof include a plastic film provided with a thin film of indium oxide, ITO or the like, paper coated with or impregnated with a conductivity imparting material, and a plastic film.
These conductive supports are used in a suitable shape such as a drum shape, a sheet shape, and a plate shape, but are not limited thereto. Further, if necessary, the surface of the conductive support can be subjected to various treatments within a range that does not affect the image quality. For example, surface oxidation treatment, chemical treatment, coloring treatment, or irregular reflection treatment such as graining can be performed.

In the present invention, on the conductive support,
An undercoat layer may be provided. The undercoat layer has an action of preventing injection of electric charges from the conductive support to the photosensitive layer during charging of the photosensitive layer, and an adhesive layer for temporarily adhering and holding the photosensitive layer to the conductive support. Or, in some cases, the function of preventing the reflected light of the conductive support from being reflected.

The binder resin used for this undercoat layer is
Polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-
Vinyl acetate copolymer resin, polyvinyl alcohol resin,
Water-soluble polyester resin, nitrocellulose, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, polyacrylic acid, polyacrylamide, zirconium chelate compound, titanyl chelate compound, titanyl alkoxide compound, organic titanyl compound, silane coupling agent A known material such as can be used.

In order to form the undercoat layer, a coating solution containing the above-mentioned materials may be applied. The coating method includes a blade coating method, a wire bar coating method,
Conventional methods such as a spray coating method, a dip coating method, a bead coating method, an air knife coating method and a curtain coating method can be used.
The thickness of the undercoat layer is set in the range of 0.01 to 10 μm, preferably 0.05 to 2 μm.

In the present invention, the photosensitive layer formed on the conductive support may have a single-layer structure or a laminated structure in which the charge-generating layer and the charge-transporting layer are functionally separated. Good. When the photosensitive layer has a laminated structure, the charge generation layer and the charge transport layer may be laminated in either order. In the case of a single layer structure, the photosensitive layer is composed of a charge generating material, a charge transporting material and a binder resin. In the case of a laminated structure, the charge generation layer is composed of a charge generation material and a binder resin, and the charge transport layer is composed of a charge transport material and a binder resin.

In the present invention, as the charge generating material in the above-mentioned photosensitive layer, amorphous selenium, crystalline selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium alloys, inorganic oxides such as zinc oxide and titanium oxide are used. Organic pigments and dyes such as photoconductive materials, phthalocyanine-based, squarylium-based, anthanthrone-based, perylene-based, azo-based, anthraquinone-based, pyrene-based, pyrylium salts, and thiapyrylium salts are used.

As the charge transport material, oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole and 1,3,5
-Triphenylpyrazoline, 1- [pyridyl- (2)]
Pyrazoline derivatives such as -3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, aromatic tertiary amino compounds such as triphenylamine and dibenzylaniline, N, N'-diphenyl-N,
Aromatic tertiary diamino compounds such as N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine, 3- (4'-diethylaminophenyl)-
5,6-di (4'-methoxyphenyl) -1,2,4-
1,2,4-triazine derivatives such as triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1'-diphenylhydrazone, 2-phenyl-4-
Quinazoline derivatives such as styrylquinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran, α-such as p- (2,2′-diphenylvinyl) -N, N-diphenylaniline Stilbene derivative, "Journal of Image"
g Science “29; 7-10 (1985), enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole and its derivatives, poly-γ-carbazole ethylglutamate and its derivatives, and Known charge generating materials such as pyrene, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-biphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole-formaldehyde resin can be used, but are not limited thereto. The charge transport material may be used alone or in combination of two or more.

In the present invention, as the binder resin for the photosensitive layer, a polycarbonate resin composed of the repeating structural unit represented by the structural formula (I) and a polycarbonate resin composed of the repeating structural unit represented by the structural formula (II) are used. Is used. Specific examples of the polycarbonate resin composed of the repeating structural unit represented by the structural formula (II) include:
Examples of the modified polycarbonate resin include repeating structural units represented by the following structural formulas (II) -a and (II) -b.

[Chemical 3] When the photosensitive layer has a laminated structure, the polycarbonate resin can be used as a binder resin for both the charge generation layer and the charge transport layer, but is particularly preferably used as a binder resin for the charge transport layer.

With respect to the viscosity average molecular weight, in the case of a polycarbonate resin comprising a repeating structural unit represented by the above structural formula (I), the molecular weight of the above polycarbonate resin is in the range of 30,000 to 90,000. In the case of a polycarbonate resin composed of the repeating structural unit represented by the structural formula (II), 20,
Those in the range of 000 to 50,000 are used. However, in that case, the molecular weight of the polycarbonate resin composed of the repeating structural unit represented by the structural formula (I) is higher than that of the polycarbonate resin composed of the repeating structural unit represented by the structural formula (II). is necessary. This is because when the former one having a lower molecular weight than the latter is used, fine abrasion and scratches may occur on the surface of the photosensitive layer during long-term use, and toner filming may occur.

Further, a polycarbonate resin comprising a repeating structural unit represented by the structural formula (I) and a structural formula (II)
The compounding ratio (weight) with the polycarbonate resin composed of the repeating structural unit represented by is 95: 5 to 60:40.
It is preferable to set in the range of. If the compounding ratio is greater than 95: 5, toner filming is likely to occur, and if it is less than 60:40, abrasion scratches are likely to occur.

For the photosensitive layer, the above-mentioned charge generating material or charge transporting material, or both of them and a binder resin are dispersed or dissolved in a suitable solvent, and the obtained coating solution is applied onto a conductive support. Can be formed by.

Hereinafter, a method for producing the photosensitive layer having a laminated structure will be described. The charge generation layer can be formed by applying or drying a coating solution obtained by dispersing or dissolving the charge generation material and the binder resin in an appropriate solvent.

The compounding ratio (weight ratio) of the charge generating material and the binder resin in the charge generating layer is preferably in the range of 10: 1 to 1:10. As the solvent used for the coating liquid, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane,
Usual organic solvents such as tetrahydrofuran, methylene chloride, chloroform and the like can be mentioned, and they can be used alone or in combination of two or more kinds. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method and a curtain coating method can be used. The thickness of the charge generation layer is usually 0.05 to 40.
μm, preferably 0.05 to 25 μm.

The charge transport layer can be formed by applying a solution prepared by dissolving the charge transport material and the polycarbonate resin in a suitable solvent and drying the solution. Examples of the solvent used for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenated fats such as methylene chloride, chloroform and ethylene chloride. Group hydrocarbons, tetrahydrofuran,
Cyclic or linear ethers such as dioxane, ethylene glycol and diethyl ether, or a mixed solvent thereof can be used. The compounding ratio (weight ratio) of the charge transport material and the binder resin is preferably 10: 1 to 1: 5. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method and a curtain coating method can be used. The thickness of the charge transport layer is generally set to 2 to 100 μm, preferably 10 to 40 μm.

Additives such as antioxidants and light stabilizers are added to the photosensitive layer for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, light or heat generated in the copying machine. be able to. Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroindanone and their derivatives,
Examples thereof include organic sulfur compounds and organic phosphorus compounds. Examples of the light stabilizer include benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine derivatives. The electrophotographic photosensitive member of the present invention may contain at least one electron-accepting substance for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use. Examples of the electron accepting substance that can be used in the electrophotographic photoreceptor of the present invention include, for example, succinic anhydride, maleic anhydride, dibromomaleic anhydride,
Phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitro Examples thereof include benzoic acid and phthalic acid. Among these, fluorenone type, quinone type, and benzene derivatives having an electron-withdrawing substituent such as Cl, CN, and NO ₂ are particularly preferable.

[0023]

EXAMPLES The present invention will be described below with reference to examples. In addition, in an Example, "part" means a "weight part." Example 1 A zirconium compound (trade name: Organix ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.) on an aluminum pipe substrate.
A solution consisting of 10 parts and 1 part of a silane compound (trade name: A1110, manufactured by Japan Junker Co., Ltd.), 40 parts of i-propanol and 20 parts of butanol was applied by a dip coating method, and dried by heating at 150 ° C. for 10 minutes, An undercoat layer having a film thickness of 0.1 μm was formed.

Next, 1 part of the x-type metal-free phthalocyanine crystal was mixed with polyvinyl butyral resin (trade name: S-REC B).
MS, manufactured by Sekisui Chemical Co., Ltd.) 1 part and cyclohexanone 1
Mix with 00 parts and 1 with a sand mill with glass beads
After being treated and dispersed for a period of time, the obtained coating liquid is applied onto the above-mentioned undercoat layer by a dip coating method, and the temperature is 100 ° C.
Was heated and dried for 10 minutes to form a charge generation layer having a film thickness of 0.25 μm.

Next, 4 parts of N-ethylcarbazole-3-aldehyde diphenylhydrazone and the above structural formula (I)
4 parts by weight of a polycarbonate resin (viscosity average molecular weight 62300) composed of the repeating structural unit represented by and a polycarbonate resin (viscosity average molecular weight 39000) composed of the repeating structural unit represented by the structural formula (II) -a 2
Part is dissolved in 50 parts of monochlorobenzene, and the obtained coating solution is applied onto the charge generation layer by a dip coating method,
It was dried at 135 ° C. for 1 hour to prepare an electrophotographic photoreceptor having three layers.

A copying machine (A-color manufactured by Fuji Xerox Co., Ltd.) which is formed by exposing the electrophotographic photosensitive member to a semiconductor laser.
630), copy 30,000 sheets, wear the surface of the photoconductor,
The presence or absence of image defects due to scratches and toner filming, and electrical characteristics were examined. The results are shown in Table 1.

Example 2 In Example 1, instead of the polycarbonate resin composed of the repeating structural unit represented by the structural formula (II) -a, the polycarbonate composed of the repeating structural unit represented by the structural formula (II) -b. Resin (Viscosity average molecular weight 350
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that (00) was used, and the same evaluation was performed. The results are shown in Table 1.

Example 3 In Example 1, a polycarbonate resin having a repeating structural unit represented by the structural formula (I) (viscosity average molecular weight of 80000) was used, and the structural formula (I
I) An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a polycarbonate resin (viscosity average molecular weight 21,000) consisting of repeating structural units represented by -a was used, and the same evaluation was performed. The results are shown in Table 1.

Example 4 In Example 1, the compounding ratio of the polycarbonate resin composed of the repeating structural unit represented by the structural formula (I) and the polycarbonate resin composed of the repeating structural unit represented by the structural formula (II) -a ( An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the weight) was 3: 3, and the same evaluation was performed. The results are shown in Table 1.

Comparative Example 1 Example 1 is the same as Example 1 except that only the polycarbonate resin (viscosity average molecular weight 62300) comprising the repeating structural unit represented by the structural formula (I) is used as the binder resin for the charge transport layer. An electrophotographic photoreceptor is prepared in the same manner as
The same evaluation was made. The results are shown in Table 1.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that the viscosity average molecular weight of the polycarbonate resin composed of the repeating structural unit represented by the structural formula (I) was set to 30,000. Was prepared and the same evaluation was performed. The results are shown in Table 1.

[0032]

[Table 1]

[0033]

The electrophotographic photoreceptor of the present invention comprises, as a binder resin, a polycarbonate resin comprising a repeating structural unit represented by the structural formula (I) and a repeating structural unit represented by the structural formula (II). By using a resin containing a polycarbonate resin, the high coating strength is maintained, the abrasion resistance is excellent, the adhesion of foreign matter such as toner filming does not occur, and the electrical and image quality characteristics are improved. Is excellent in.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomio Kobayashi 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Takematsu Plant (72) Inventor Taketoshi Hoshizaki 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Takematsu Business In-house

Claims (2)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive support and at least a photosensitive layer provided thereon, wherein the photosensitive layer is a polycarbonate resin comprising a repeating structural unit represented by the following structural formula (I) as a binder resin. And a polycarbonate resin comprising a repeating structural unit represented by the following structural formula (II) and having a molecular weight lower than that of the polycarbonate resin. [Chemical 1] (In the formula, X ₁ and X ₂ each represent a hydrogen atom or an alkyl group.) 2. The compounding ratio (weight) of the polycarbonate resin comprising the repeating structural unit represented by the structural formula (I) and the polycarbonate resin comprising the repeating structural unit represented by the structural formula (II) is 95: 5 to 60:
The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is in the range of 40.