JPH0363652A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance bending resistance of a belt type photosensitive layer, its abrasion resistance, and its high-speed response performance by using a specified polycarbonate as the binder resin of a photosensitive layer. CONSTITUTION:The photosensitive layer contains as the binder resin the polycarbonate represented by formula I in which each of R1 and R2 is H, alkyl, aryl, or the like; each of R3 and R4 is H, alkyl, or aryl optionally substituted by alkyl; and (n) is 10 - 1000. For example, the photosensitive body can be obtained by forming an aluminum layer on a polyethylene terephthalate film, and successively laminating an undercoat layer, an electric charge generating layer containing trigonal system selenium and polyvinyl butyral and a charge transfer layer containing a triphenylamine type compound and the polycarbonate of formula I, preferably, that of formula II (n =10 - 1000).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor using a specific polycarbonate resin as a binder resin.

2. Description of the Related Art In recent years, electrophotographic photoreceptors have been widely used in fields such as copying machines and laser beam printers because they have the advantage of being able to print at high speed and with high print quality. These electrophotographic photoreceptors used in electrophotographic devices are cheaper and easier to manufacture than conventional electrophotographic photoreceptors using inorganic photoconductive materials such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, and cadmium sulfide. Research on electrophotographic photoreceptors using organic photoconductive materials, which have excellent advantages in terms of ease of disposal and disposal, has become active. Among these, a functionally separated multilayer organic photoreceptor, which has a charge generation layer that generates charges upon exposure to light and a charge transport layer that transports charges, has excellent sensitivity,
It has excellent electrophotographic properties such as chargeability and repeated stability, and various proposals have been made and put into practical use.

Furthermore, various flexible electrophotographic photoreceptors have been proposed as organic photoreceptors, in which a photosensitive layer is formed on a film of polyethylene terephthalate or the like on which a conductive layer is formed by a method such as vapor deposition. This type of electrophotographic photoreceptor can be processed into a belt shape and used repeatedly in a copying machine, so it has the advantage of expanding the degree of freedom in the shape of the copying machine hardware. For this purpose, various materials have been studied for the binder resin of electrophotographic photoreceptors, and for example, it is known to use polymethyl methacrylate, polyester, polycarbonate resin, etc. (Japanese Patent Laid-Open No. 57-4051 and Kaisho 8
0-172044).

Problems to be Solved by the Invention By the way, when a coating film of a photosensitive layer is formed by a coating process using the binder resin proposed in the past, a belt-shaped electrophotographic photoreceptor having relatively good durability can be obtained. ,
It cannot be said that its mechanical strength is necessarily at a sufficient level, and when it is repeatedly rotated for a long period of time in a belt drive device in a copying machine, cracks occur in the photosensitive layer, which causes crack patterns on the copied image. However, there remained the problem of the appearance of Additionally, when a photoreceptor is used repeatedly, the surface of the photoreceptor layer wears down, reducing the sensitivity of the photoreceptor.
There have been problems in that fog occurs on copies, the charging potential changes, and the copy density decreases. Therefore, it has been desired to develop a binder resin that can form a photosensitive layer having sufficient durability when used as a belt-shaped electrophotographic photoreceptor.

Furthermore, when these electrophotographic photoreceptors are used in high-speed copying machines, not only the photoreceptor must have high sensitivity, but also a fast decay rate of the photoreceptor potential is required.

This means that the carrier mobility in the charge transport layer is large. However, the conventional material system in which a charge transporting agent is added to a binder resin cannot be said to have sufficient mobility to be compatible with all high-speed copying machines. Until now, it has been common knowledge that carrier mobility is controlled by the charge transport material and its blending amount, so the approach of finding a binder resin that is effective for improving mobility has not been sufficiently studied. It had not been done.

The present invention has been made in view of the above-mentioned circumstances, and aims to solve the above-mentioned problems in the conventional technology.

That is, an object of the present invention is to have a coating film on the surface of a photoconductor that has high bending strength, that when used repeatedly as a belt-shaped photoconductor, defects such as cracks do not occur in the coating film, and that the coating film has strong abrasion resistance. An object of the present invention is to provide an electrophotographic photoreceptor having excellent durability and durability.

Yet another object of the present invention is to provide an electrophotographic photoreceptor having high-speed response that can be applied to high-speed copying machines.

Means for Solving the Problems As a result of various studies in view of the above points, the present inventors have found that polycarbonate resin represented by the following structural formula (1) as a binder resin for the photosensitive layer has a high durability related to mechanical strength. By using this property, it is possible to solve the problem of mechanical deterioration of the photosensitive layer when a belt-shaped electrophotographic photoreceptor is repeatedly rotated for a long period of time in a copying machine, and also to improve the stability of the photosensitive layer. The present inventors have discovered that the charge transport ability of the molecule can be dramatically improved, leading to the completion of the present invention.

The present invention is an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, and is characterized in that the photosensitive layer contains a polyester resin represented by the following structural formula (1) as a binder resin.

R1 4 (wherein R1 and R2 are each a hydrogen atom, an alkyl group, an aryl group or an aryl-substituted alkyl group, or an atomic group necessary for R1 and R2 to form a carbocycle or a lactone ring together) (wherein R3 and R4 each represent a hydrogen atom, an alkyl group, or an alkyl-substituted or unsubstituted aryl group, and n is lO to 1000) Among them, the polycarbonate resin represented by the following structural formula (n) is particularly Shows excellent properties.

(n is too to tooo) In the electrophotographic photoreceptor of the present invention, the conductive support is a metal drum made of aluminum, copper, iron, zinc, nickel, etc., and aluminum on a sheet, paper, plastic, or glass. , depositing metals such as copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel, copper-indium, etc., or depositing conductive metal compounds such as indium oxide, tin oxide, or metal foil. Laminate or carbon black, indium oxide, tin oxide
Known materials such as drum-shaped, sheet-shaped, plate-shaped materials can be used, which are conductive-treated by dispersing antimony oxide powder, metal powder, copper iodide, etc. in a binder resin and applying the coating.

Further, if necessary, the surface of the conductive support can be subjected to various treatments as long as the image is not affected.

An undercoat layer having a barrier function or an adhesive function may be provided on the conductive support, if necessary. As the material constituting the undercoat layer, resins such as polyvinyl butyral, polyvinyl alcohol, casein, polyamide, cellulose, gelatin, polyurethane, and polyester, and metal oxides such as aluminum oxide can be used.

The photosensitive layer formed on the conductive substrate may have a single layer structure or a laminated structure in which a charge generation layer and a charge transport layer are functionally separated. In the case of a laminated structure, the charge generation layer and the charge transport layer may be stacked in any order.

These photosensitive layers are composed of a coating film containing a charge-generating substance, a charge-transporting substance, or both in a binder resin.

As the charge generating substance, amorphous selenium, crystalline selenium
Tellurium alloys, selenium-arsenic alloys, other selenium compounds and selenium alloys, inorganic photoconductors such as zinc oxide and titanium oxide, phthalocyanine-based, squalium-based, anthrone-based, perylene-based, azo-based, anthraquinone-based,
Organic pigments and dyes such as pyrene, biryllium salts, and thiapyrylium salts are used.

The charge generation layer is formed by vacuum deposition or by dispersing and coating a charge generation substance together with an organic solvent and a binder resin.

Examples of the binder resin in the charge generation layer include the following. That is, in addition to the polycarbonate resin represented by the above structural formula (1) used in the present invention, bisphenol A type or bisphenol 2
Types of polycarbonate resin, polyester resin, etc.
Methacrylic resin, acrylic resin, polyvinyl chloride resin,
Polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, silicone resin, silicone
Alkyd resin, phenol-formaldehyde resin,
These include styrene-alkyd resin, poly-N-vinylcarbazole resin, and the like.

These binder resins can be used alone or in combination of two or more.

The blending ratio (weight ratio) of the charge generating substance and the binder resin is 10
A range of :l=l:10 is desirable. Further, the thickness of the charge generation layer is generally 0. O1-5-1 preferably 0.0
It is set in the range of 5 to 2.0-.

As the charge transport substance, quinone compounds such as p-benzoquinone, chloranil, bromoanil, anthraquinone,
Tetracyanoquinodimethane compounds, fluorenone compounds such as 2.4.7-)linitrofluorenone, electron-withdrawing substances such as xanthone compounds, benzophenone compounds, cyanovinyl compounds, ethylene compounds, triphenylamine compounds , aryl alkane compounds, aryl-substituted ethylene compounds, benzidine compounds, stilbene compounds, anthracene compounds, or electron-donating substances such as polymers having a group consisting of these compounds in the main chain or subchains. can give.

In the present invention, a polycarbonate resin represented by the above formula (1) is used as the binder resin of the charge transport material. Specific examples of this polycarbonate resin include those illustrated below.

However, in the formula, n is the degree of polymerization, and the molecular weight is 15.000 to 10.
The value corresponds to 0°000, preferably in the range of 20,000 to 50,000.

Below is the margin CH3. The charge transport layer is formed by applying a solution in which the charge transport material described above and the polycarbonate resin described above are dissolved in an appropriate solvent.
It can be formed by drying. Typical solvents used to form the charge transport layer include aromatic hydrocarbons such as benzene, toluene and chlorobenzene, ketones such as acetone and 2-butanone, methylene chloride, chloroform, Halogenated aliphatic hydrocarbons such as ethylene chloride, cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, etc., or mixed solvents thereof can be used.

The blending ratio of the charge transport material and the above polycarbonate resin is l
O:1-1:5 is preferred. Further, the thickness of the charge transport layer is generally set in the range of 5 to 50 m, preferably 10 to 30 m.

The polycarbonate resin in the present invention can be produced by reacting a corresponding intermediate bisphenol compound with phosgene. Next, a typical synthesis example will be shown.

Synthesis Example 1 (Synthesis of Exemplified Compound (2)) 0.2 mol of a bisphenol compound represented by the following structural formula, 400 ml of a 4.7% aqueous sodium hydroxide solution, and 850 ml of methylene chloride were added to a 2-liter reactor. While stirring vigorously, phosgene was blown in at a rate of 400 ml/min for 15 minutes.

The reaction temperature was maintained at 15°C, and 40ml of 13.7% sodium hydroxide, 0.2g of riftylbenzylammonium chloride and 0.3ml of triethylamine were added, and stirring was continued at 23°C for 1 hour to carry out the polycondensation reaction. carried out. After the reaction was completed, the product was diluted with 400 ml of methylene chloride and washed successively with 147 ml of water, 0.5 g of 0.01N hydrochloric acid, and 1 g of water. The obtained organic layer was poured into 52 methyl alcohol to precipitate a white polymer, and after filtration, 1
The mixture was dried at 00° C. for 12 hours to obtain 80 g of polycarbonate resin: Exemplified Compound (2) (molecular weight 45,000).

Synthesis Example 2 (Synthesis of Exemplary Compound (5)) The polycondensation reaction was repeated in exactly the same manner as in Synthesis Example 1, except that the bisphenol compound in Synthesis Example 1 was replaced with a bisphenol compound having the following structure, to produce polycarbonate. Resin 2 exemplified compound (2) (molecular weight 41.0
00) 89g was obtained.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 10 parts by weight of polyvinyl alcohol resin,
A coating solution consisting of 150 parts by weight of n-propyl alcohol and 40 parts by weight of water was applied and dried to a film thickness of 0.5
A subbing layer of fi was formed. Additionally, 9 parts by weight of trigonal selenium, 2 parts by weight of polyvinyl butyral resin (manufactured by Sekisui Chemical ■, S-LEC BM-1), and 8 parts by weight of n-butyl alcohol.
The mixture consisting of 0 parts by weight was placed in a ball millbot and milled for 60 hours using 1/8 inch diameter SUS balls as milling members, and then further diluted with 30 parts by weight of n-butyl alcohol and stirred. The obtained dispersion liquid is applied onto the above-mentioned undercoat layer and dried to obtain a film thickness of O, a.
A charge generation layer of m was formed. Next, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-0,1'
4 parts by weight of [biphenyl]-4,4'-diamine and 8 parts by weight of the polycarbonate resin obtained in Synthesis Example 1 were added to 55 parts by weight of methylene chloride, dissolved, and coated and dried to form a charge transport film with a thickness of 20 m. A three-layer electrophotographic photoreceptor was prepared by forming layers.

The photosensitive layer coating of the electrophotographic photoreceptor produced as described above was peeled off from the conductive substrate, and a bending test was conducted using a bending strength tester up to 5,000 times. Further, the above electrophotographic photoreceptor was processed into a belt shape, and the belt was attached to a copying machine having a belt rotation drive device, and a copying running test was conducted for up to 100,000 cycles. The results are shown in Table 1.

This electrophotographic photoreceptor was charged to 800V using a corona charger and subjected to xenon flash exposure of 4μ5138, and the time change in surface potential decay was measured using a Kawaguchi Denki EP A-8100 Paper Analyzer. . The results are shown in FIG.

Example 2 The same procedure as Example 1 was used except that the polycarbonate resin obtained in Synthesis Example 2 was used as the binder resin for the charge transport layer.
An electrophotographic photoreceptor was prepared by processing in the same manner as in the above method, and the same evaluation was performed. The results are shown in Table 1. FIG. 1 shows the change in surface potential over time after flash exposure.

Comparative Example 1 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that a polycarbonate resin represented by the following structural formula (A) was used as the binder resin of the charge transport layer.
Evaluation was conducted in the same manner. The results are shown in Table 1. FIG. 1 shows the change in surface potential over time after flash exposure.

(n is the degree of polymerization, a value corresponding to the molecular weight! 110,000) Comparative Example 2 All examples were the same as in Example 1 except that a polycarbonate resin represented by the following structural formula (B) was used as the binder resin of the charge transport layer. An electrophotographic photoreceptor was produced by processing in the same manner as in the method of
A similar evaluation was conducted. The results are shown in Table 1. FIG. 1 shows the change in surface potential over time after flash exposure.

(n is the degree of polymerization, which corresponds to a molecular weight of 40.000) Table 1

[Brief explanation of drawings]

FIG. 1 is a graph showing the attenuation state of the surface potential of the electrophotographic photoreceptors of Examples and Comparative Examples.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, the photosensitive layer has the following structural formula (
An electrophotographic photoreceptor comprising a polycarbonate resin represented by I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 and R_2 are each a hydrogen atom, an alkyl group, an aryl group, or an aryl-substituted alkyl group,
or R_1 and R_2 together represent an atomic group necessary to form a carbocycle or lactone ring, R_3 and R_4 each represent a hydrogen atom, an alkyl group, or an alkyl-substituted or unsubstituted aryl group, and n is 10～
1000) (2) The electrophotographic photoreceptor according to claim 1, wherein the polycarbonate resin is a polycarbonate resin represented by the following structural formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, n is 10 to 1000)