JPH0371143A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide a separated function type laminated electrophotographic sensitive body having high sensitivity, low residual potential, durability and a high response speed and hardly undergoing optical fatigue even after repeated use by forming an electric charge transferring layer composed of a 1,1,4,4- tetraphenyl-1,3-butadiene deriv. and specified polycarbonate resin as a binding resin. CONSTITUTION:An electric charge generating layer and an electric charge transferring layer are formed on an electrically conductive support and the electric charge transferring layer is composed of an electric charge transferring material represented by structural formula I and polycarbonate resin consisting of monomeric units represented by general formula II. The pref. average mol. wt. of the polycarbonate resin is 15,000-200,000, especially 20,000-120,000. The mixing ratio between the electric charge transferring material and the polycarbonate resin is regulated to (1:20)-(20:1), especially (1:5)-(6:4).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor using a charge generating material and a charge transport layer.

BACKGROUND OF THE INVENTION In recent years, in electrophotographic photoreceptors, methods have been actively proposed in which the two functions of a photoconductive substance, that is, the generation of charge carriers and the transport of generated charges, are performed by separate organic compounds. For example, U.S. Patent No. 3,791,8
Specification No. 26). In this method, by combining a substance with high charge carrier generation efficiency and a substance with high charge transport ability, it is possible to obtain a highly sensitive electrophotographic photoreceptor.

However, this does not mean that it is necessarily possible to simultaneously satisfy the various characteristics required of an electrophotographic photoreceptor, such as high surface charge, high charge retention ability, high photosensitivity, and almost no residual potential. isn't it. In order to obtain a practical electrophotographic photoreceptor having such various characteristics, high generation efficiency of charge carriers in the charge generation material,
In addition to rapid transport of charge carriers in a charge transporting material, injection of charge carriers from a charge generating material into a charge transporting material, or charge carrier injection from a charge generating layer to a charge transporting layer in a laminated electrophotographic photoreceptor is important. Another important factor is that the injection is performed efficiently. Attempts have been made to explain this charge injection efficiency in terms of its correlation with the ionization potential of the charge transport material, but it still lacks generality and has not been uniformly explained for charge transport materials in general.

Charge injection depends on the characteristics of the interface between the charge generating material (or charge generating layer) and the charge transporting material (or charge transporting layer), and is not the same between various materials.

In an electrophotographic photoreceptor having a functionally separated photosensitive layer, it is possible to obtain high sensitivity by selecting and combining substances with each function as described above, but on the other hand, conventional electrophotographic photoreceptors of this type The photoreceptor has drawbacks such as a reduced ability to recover its original charging characteristics or a reduced photosensitivity when used repeatedly according to an electrophotographic process, shortening the life of the photoreceptor. In other words, if the actual electrophotographic processes of charging, exposure, and cleaning are repeated many times, one of the following may occur: fluctuations in surface charge after charging, decrease in charge retention, decrease in photosensitivity, increase in residual potential, etc. one or more optical fatigue phenomena occur;
This is a major practical problem because it significantly degrades the performance of electrophotographic photoreceptors. Furthermore, as electrophotographic copying machines, printers, and the like have become faster in recent years, electrophotographic photoreceptors are required to have higher sensitivity and faster response. The response speed of a photoreceptor depends on the mobility of charge carriers in a charge transporting material, and there is a strong desire to develop a charge transporting material with high mobility.

It is also known that in electrophotographic photoreceptors having a functionally separated photosensitive layer, the characteristics of the electrophotographic photoreceptor vary depending on the combination of charge transport material and binder resin in the charge transport layer. There is.

By the way, various proposals have been made regarding the use of butadiene derivatives in electrophotographic photoreceptors.

For example, M. Kleinerman
J. Chem, Phys., 37.1825.
(19B2) and JP-A-52-24248, same [12
1,1,4,4-tetraphenyl-1,3-butadiene and its derivatives, alkyl-, alkoxy-, and halogen-substituted-1,1,4,4-tetraphenyl-1,1- described in Japanese Patent Publication No. 30255. Butadien et al., C.E., 11.
Chem, Commun, by Bawn et al.
, 599. 1.1.4.4-tetrakis(p-dimethylphenyl)-1,8-butadiene described in (19fJ), or JP-A-Shoez-go255 and JP-A-62-2872
Tetraphenylbutadiene derivatives represented by the following general formula (wherein R represents a lower alkyl group) disclosed in Japanese Patent No. 57 are known.

Problems to be Solved by the Invention As mentioned above, it is desired to develop a charge transport material that satisfies the above-mentioned requirements for functionally separated electrophotographic photoreceptors. The above-mentioned butadiene derivatives are still insufficient. For example, 1. L
, 4,4-tetraphenyl-1,3-butadiene and its derivatives, alkyl, alkoxy, and halogen substituted products, have extremely low sensitivity and poor solubility in binder resins. In addition, 1,1,4,4-tetrakis(p-dimethylphenyl'I-1,3-butadiene has no charge retention ability and cannot be used as a photoreceptor in practice. In addition, the above general formula (m) The electrophotographic photoreceptor described in JP-A-62287257 using the tetraphenylbutadiene derivative represented by the formula does not yet have sufficient sensitivity.

The present invention has been made in view of the above circumstances. Therefore, an object of the present invention is to provide a functionally separated laminated electrophotographic photoreceptor with high sensitivity, low residual potential, low optical fatigue even after repeated use, durability, and high response speed. There is a particular thing.

The present inventors have discovered that 1,1,4,4-tetraphenyl-1,
By combining various 3-butadiene derivatives, we conducted intensive research on compounds suitable for producing even higher performance electrophotographic photoreceptors. We focused on the fact that differences in the combination of the charge transport material and the binder resin affect the electrophotographic properties of the electrophotographic photoreceptor, and 1, 1, 4.
As a result of investigating combinations of 4-tetraphenyl-1,3-butadiene derivatives and binder resins, the inventors discovered that a specific combination exhibits excellent electrophotographic properties, leading to the completion of the present invention. Ta.

Means for Solving the Problems The present invention provides an electrophotographic photoreceptor having a photosensitive layer comprising at least a charge generation layer and a charge transport layer on a conductive support, wherein the charge transport layer has at least the following structural formula (1). It is characterized by containing a polycarbonate resin composed of the charge transporting material shown below and a monomer unit shown by the following general formula (II).

(In the formula, X represents a chlorine atom or a bromine atom.) The present invention will be described in detail below.

FIG. 1 is a schematic cross-sectional view for explaining the layer structure of the electrophotographic photoreceptor of the present invention. In FIG. 1, a charge generation layer 2 and a charge transport layer 3 are provided on a conductive support l, and this charge transport layer includes a charge transport layer represented by the above structural formula (I) and a charge transport layer represented by the general formula ( It is composed of a polycarbonate resin composed of monomer units represented by II).

In the present invention, examples of the conductive support include a metal pipe, a metal plate, a metal sheet, a metal foil, a polymer film subjected to conductive treatment, a polymer film provided with a vapor-deposited layer of metal such as A1, SnO2, etc. A polymer film or paper coated with metal oxide, quaternary ammonium salt, etc. is used.

The charge generation layer formed on the conductive support may be obtained by depositing a charge generation material on the conductive support, for example, a-3eSa-8L.

Examples include vapor deposited films such as As2Se3.5eTe.

Further, the charge generation layer may be formed by applying a coating liquid containing a charge generation material and a binder resin as main components. In that case, the charge generating material and adhesive resin are:
Any known material can be used. For example, charge generating materials include inorganic semiconductors such as trigonal Se, bisazo compounds, trisazo compounds, phthalocyanines, pyrylium compounds, squareium compounds,
Organic pigments such as anthrone pigments, perylene pigments, and phthalocyanine pigments can be used, and as binder resins, polystyrene, silicone resins, polycarbonate resins,
Acrylic resins, methacrylic resins, polyesters, vinyl polymers, celluloses, alkyd resins, etc. can be used.

The thickness of the charge generation layer is set to about 0.05 to 10/Zlll.

The charge transport layer provided on the charge generation layer is prepared by combining the charge generation layer represented by the above structural formula (I) and a polycarbonate resin composed of monomer units represented by the above general formula (II) in a suitable solvent. It can be formed by applying a solution obtained by dissolving it in

The average molecular weight of the polycarbonate/resin composed of monomer units represented by the above general formula (n) is 1.
5,000-200,000, especially 20,000-1
Preferably, a range of 20,000 is used. Further, the mixing ratio of the charge transporting material represented by the above structural formula (I) and the polycarbonate resin composed of the monomer represented by the general formula (n) is L220 to 20:1, In particular, it is set in the range of 1:5 to 6:4.

The thickness of the charge transport layer is 2 to 100 m, preferably 10 to 4 m.
It is set to 0 immediately.

In the electrophotographic photoreceptor of the present invention, an adhesive layer or an intermediate layer may be provided as necessary.

Example Next, the present invention will be explained by examples and comparative examples. do.

Example 1 (i) 0.2 g of chlorcyan blue was added to polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., Niepilon E-2000).
was mixed with 4 g of dichloroethane solution containing 5%, and after adding 20 Ilρ of dichloroethane, 1-
A coating liquid for forming a charge generation layer is prepared by pulverizing the following, and this is applied onto a polyester film on which aluminum has been vapor-deposited using a wire bar, dried at 45°C, and a charge generating layer having a thickness of about 11 m is coated. A generation layer was formed.

On the other hand, the charge transport material represented by the structural formula (1) [1,l
-Bis(P-diethylaminophenyl)-4,4-diphenylbutadiene-1,8) 0.1 g was added to a polycarbonate resin (molecular weight 40 , 000) in 2 g of dichloroethane solution containing 5% to prepare a coating solution for forming a charge transport layer.

1 Apply this coating solution onto the charge generation layer using a doctor blade so that the dry film thickness is 15 mm, and
A charge transport layer was formed by drying at 5° C., and an electrophotographic photoreceptor was prepared.

(11) The electrophotographic properties of the above electrophotographic photoreceptor were measured by a static method using an electrostatic copying paper tester model rSP-428 (manufactured by Kawaguchi Denki Seisakusho).

That is, the electrophotographic photoreceptor was charged by -8 KV corona discharge for 5 seconds, and the surface potential was V. (unit:
After holding it in a dark place for 5 seconds, a tungsten lamp is used to irradiate it with light with an illuminance of 5 lux to reduce the surface potential to 172 and 1/B. ) and El/6 (lux seconds), and the surface residual potential VR (volts) after irradiation with light at an illuminance of 5 lux for 20 seconds was measured. The results are shown in Table 1.

2 Example 2 In Example 1, instead of the polycarbonate resin constituted by the monomer represented by the structural formula (ll-1),
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that a polycarbonate resin (molecular weight 58.000) composed of a monomer represented by the following structural formula (n-2) was used, and the same procedure was carried out. The photoreceptor characteristics were evaluated. The results are shown in Table 1.

Example 3 and Example 4 In Examples 1 and 2, except that chlorcian blue was replaced with τ-phthalocyanine (manufactured by Toyo Ink Manufacturing ■),
Electrophotographic photoreceptors were prepared in the same manner as in Examples 1 and 2, and the photoreceptor characteristics were evaluated in the same manner. The result is the first
Shown in the table.

Examples 5 and 6 Titanyl phthalocyanine (manufactured by Sanyo Color Co., Ltd.) was deposited on the aluminum 3-lam film deposited on the polyester film.
was deposited to a thickness of 0.1 am at 10-' Torr.

The above structural formula (
A coating solution for forming a charge transport layer was prepared by dissolving o and t g of the charge transport layer shown in 1). This coating solution was applied onto the titanyl phthalocyanine vapor-deposited film using a doctor blade so that the film thickness after drying was 15 cm, and dried at 45° C. to prepare an electrophotographic photoreceptor.

Regarding these electrophotographic photoreceptors, the photoreceptor characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Examples 7 and 8 Electrophotographic photoreceptors were produced in the same manner as in Examples 1 and 2, respectively, except that dibromoanthanthrone (manufactured by ICI Japan ■) was used in place of chlorcian blue in Examples 1 and 2. The photoreceptor characteristics were similarly evaluated. The results are shown in Table 1.

Comparative Examples 1 to 4 4 Instead of the charge transport material in Example 1, the following structural formula (
Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that the compounds represented by III) to (Vi) were used as charge transport materials, and the photoreceptor characteristics were evaluated in the same manner. The results are shown in Table 1.

(Comparative Example 1) (Comparative Example 2) Comparative Example 5 In Example 5, instead of the polycarbonate resin composed of the monomer represented by the structural formula (II-1),
An electrophotographic photoreceptor was prepared in the same manner as in Example 5, except that a polycarbonate resin (Macrolon 5705, manufactured by Bayer) consisting of the Lliffi il1 position represented by the following structural formula (■) was used, and the photoreceptor was similarly photosensitive. Body characteristics were evaluated. The results are shown in Table 1.

(Comparative Example 3) 2H5 (Comparative Example 4) 5 Comparative Example 6 In Example 6, the following structural formula (■) was used instead of the polycarbonate resin constituted by the monomer shown by the structural formula (ll-2). An electrophotographic photoreceptor was prepared in the same manner as in Example 6, except that a polycarbonate resin consisting of 111 mer units represented by the formula (Mitsubishi Gas Chemical 6-■, weight average molecular weight 21,000) was used. The photoreceptor characteristics were evaluated. The results are shown in Table 1.

Comparative Example 7 In Example 7, instead of the polycarbonate resin composed of the monomer represented by the structural formula (ll-1),
An electrophotographic photoreceptor was prepared in the same manner as in Example 7, except that a polycarbonate resin consisting of a monomer unit represented by the following structural formula (IX) (manufactured by Yojin ■, trade name Panlite, molecular weight 25,000) was used. was prepared and the photoreceptor characteristics were similarly evaluated. The results are shown in Table 1.

In place of the charge transport material in Example 8, the above structural formula (
The compound represented by m) is used as a charge transport material, and instead of the polycarbonate resin constituted by the monomer represented by structural formula (n-2), a monomer represented by the above structural formula (■) is used. An electrophotographic photoreceptor was prepared in the same manner as in Example 8, except that a polycarbonate resin consisting of units (Macrolon 57o5, manufactured by Bayer AG) was used, and the photoreceptor characteristics were evaluated in the same manner. The results are shown in Table 1.

Margin Comparative Example 8 7 8 Effects of the Invention The electrophotographic photoreceptor of the present invention has the above-mentioned structure, has excellent charge retention ability, has a low residual potential,
In addition, it has excellent electrophotographic properties such as low optical fatigue due to charging exposure even after repeated use, high durability, high response speed, and extremely high sensitivity. Therefore, it has the properties most required in the field of electrophotographic processes and is very industrially advantageous.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the electrophotographic photoreceptor of the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support, 2... Charge generation layer, 8...
charge transport layer

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer consisting of at least a charge generation layer and a charge transport layer on a conductive support, the charge transport layer includes a charge transport material represented by at least the following structural formula (I) and a charge transport material shown below. An electrophotographic photoreceptor comprising a polycarbonate resin composed of monomer units represented by formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II)