JPH0572762A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] [Purpose] The present invention relates to an electrophotographic photosensitive member used in a printer or a copying machine, and its purpose is to improve sensitivity and stability. [Structure] Using a pyrrole as a monomer and sodium toluenesulfonate as an electrolyte, an electrolytic polymer is prepared in a propylene carbonate solution, and the solid substance of this electrolytic polymer is pulverized into a fine powder. .. This powder was mixed with a solution prepared by dissolving X-type phthalocyanine and polybutyral in cyclohexanone using polybutyral as a binder resin, and the charge generation layer was coated on an Al substrate from the dispersion-treated solution. To do. Further, a charge transfer layer is formed thereon. With such a structure, the sensitivity can be improved and the stability can be improved without increasing the residual potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor capable of improving the photosensitivity of an organic photoreceptor used in electrophotography which employs processes such as charging-exposure-developing-static elimination.

[0002]

2. Description of the Related Art Organic photoconductors (abbreviated as OPC) are capable of synthesizing materials having high sensitivity to various wavelengths by molecular design as compared with inorganic photoconductors, are non-polluting, have excellent productivity, are economical, and are inexpensive. It has such characteristics as, and active research and development is currently being conducted. Further, in terms of durability and sensitivity, which have hitherto been regarded as problems of organic photoconductors, significant improvements have been made, and some of them have been put into practical use, and are now becoming the main force of electrophotographic photoconductors.

OPC is usually used in a double layer structure of a charge generation layer (abbreviated as CGL) that absorbs light to generate carriers and a charge transfer layer (abbreviated as CTL) that moves generated carriers, and has high sensitivity. Is being measured.

Materials used for CGL (abbreviated as CGM)
As such, various organic materials such as various perylene compounds, various phthalocyanine compounds, thiapyrylium compounds, anthanthrone compounds, squarylium compounds, bisazo compounds, trisazo pigments and azurenium dyes have been investigated.

On the other hand, various hydrazone compounds, oxazole compounds, triphenylmethane compounds, arylamine compounds, etc. have been developed as materials (abbreviated as CTM) used for CTL.

Further, in recent years, there has been an increasing demand for using these organic photoconductors in the near infrared region corresponding to semiconductor laser light (780-830 nm) as photoconductors for digital recording such as laser printers. In this area, the development of organic photoconductors having high sensitivity characteristics is active. As the photoconductor in such a region, the organic photoconductor is more advantageous than the inorganic photoconductor in terms of sensitivity. These materials are used with a binder polymer by a relatively simple coating method such as a drum, belt,
Etc. are formed on the substrate. Binder polymers used for such purpose include polyester resin, polycarbonate resin, acrylic resin, acrylic-styrene resin, and the like.

[0007]

Generally, in the double-layer structure, the CG layer is applied in a thickness of about 1 micron, while the CT layer is applied in a thickness of 10 to 20 micron in order to improve sensitivity. .. At this time, because of its strength, printing durability, etc., C
Normally, the G layer is formed on the substrate side, and the CT layer is formed on the front surface side. In such a structure, only the CTM that operates by the movement of holes is put into practical use.
The multi-layer photoconductor is of a negative charging type. At present, there is a demand for further improvement in sensitivity, repeatability stability, and environmental resistance in a photoreceptor having such a structure.

In view of the above-mentioned conventional problems, the present invention has an object to improve the sensitivity and the stability of the characteristics in an organic photoconductor in which two layers of a charge generation layer and a charge transfer layer are essential. To do.

[0009]

The technical means of the present invention for achieving the above object has at least a charge generation layer and a charge transfer layer, and the charge generation layer has an electrolytic weight in addition to the charge generation agent. The electrophotographic photosensitive member is characterized by adding a coalescence.

[0010]

The present inventors say that an organic photoconductor using a charge generation layer prepared by adding an electropolymer to a charge generation agent together with a binder resin exhibits very excellent electrophotographic characteristics including stability. I got the knowledge.

Generally, the electrophotographic characteristics of the charge generation layer do not change significantly even if some additives are added, if the mixing ratio of the charge generation agent and the binder resin is optimized. However, in the present invention, the characteristics were improved when the electrolytic polymer was added.

As the electrolytic polymer, polypyrrole and polythiophene compounds were particularly excellent. The electrolytic polymer is easily formed in the form of a film on the anode electrode by an electrolysis method, but a fine powder state is desirable for good dispersion and mixing with the photosensitive material and the binder resin. The oligomerization state of the electrolytic polymer is easy to carry out the pulverization treatment. The characteristics also differ depending on the anion being doped. By using an aromatic anion as the anion, not only the photosensitivity but also the stability is improved.

As the anion, alkylbenzenesulfonic acid, alkylbenzenecarboxylic acid, alkylnaphthalenesulfonic acid, and alkylnaphthalenecarboxylic acid were particularly effective. Carbon number is 1 as an alkyl group
1 to 6 may be attached to one or more aromatic rings.
In this case, a hydrogen group may be used instead of the alkyl group.

The charge generating agent is not particularly limited, but it is required that the state in which the binder resin and the electrolytic polymer are compounded is uniform and the dispersibility is good. A phthalocyanine compound is used as a charge generating agent for a laser printer, and even if an electropolymer is added, the dispersibility with a binder resin does not deteriorate. Among phthalocyanine compounds, there are metal phthalocyanine and metal-free phthalocyanine, but metal-free phthalocyanine has very good dispersibility. Among the metal phthalocyanines, the metal is C
u, Mg, In-Cl, Al-Cl, Ti-O and the like had good dispersibility.

The organophotoreceptor prepared in this manner has improved not only sensitivity characteristics but also repeated stability and image characteristics.

[0016]

EXAMPLES Examples of the present invention will be described together with comparative examples.

Example 1 First, an electrolytic polymer was prepared in a solution of propylene carbonate using pyrrol as a monomer and sodium toluenesulfonate as an electrolyte. The solid substance of this electrolytic polymer was pulverized into a fine powder. Using polybutyral as a binder resin, this powder was dissolved in cyclohexanone in a weight ratio of 1: 4 of X-type phthalocyanine and polybutyral to prepare a solution, which was added in an amount of 10 wt% with respect to X-type phthalocyanine. After mixing, the dispersion treatment was sufficiently performed. This solution was applied as an electric charge generation layer onto an Al substrate to form a film having a thickness of 0.5 μm.

Next, as a charge transfer layer, p-diethylaminobenzaldehyde- (diphenylhydrazone) which is one of the hydrazone compounds (manufactured by Nanan Perfume Co.) and a binder resin were dissolved from a dichloromethane solution in a weight ratio of 1: 1.
The film was formed on the charge generation layer prepared above so as to have a thickness of 20 μm. At the same time, for the purpose of comparison, a charge generation layer having the same constitution and containing no electrolytic polymer was prepared.

EPA- manufactured by Kawaguchi Electric Co., Ltd. is used to measure the photosensitive characteristics.
It was performed using an 8100 Paper Analyzer. The results of the sensitivity characteristics are shown in (Table 1). Sensitivity is indicated by E1 / 2. The measurement wavelength is 780 nm. The first time as a result of the number of repetitions,
The results of the 1000th, 5000th and 10000th times are shown.

[0020]

[Table 1]

As can be seen from this (Table 1), polypyrro-
It can be seen that the addition of sodium improves the sensitivity and improves the stability without increasing the residual potential.

(Example 2) In the same manner as in Example 1, a polythiophene having an anion of sodium triisopropylnaphthalene sulfonate was prepared as an electrolytic polymer. Using τ type Cu phthalocyanine as a charge generating agent,
30 wt% of polythiophene to this phthalocyanine
% To add a solution. A photosensitive member was manufactured in the same manner as in Example 1 except for the above. The same experiment as in Example 1 was conducted. The results are shown in (Table 2).

[0023]

[Table 2]

As the electropolymer of the present invention, it was confirmed that a 5-membered heterocyclic compound having a general formula represented by the following (formula 2) is preferable.

[0025]

[Chemical 2]

[0026]

As described above, according to the present invention, the charge generation layer is composed of a binder resin, a charge generation agent, and an electrolytic polymer, and the photosensitive characteristics and stability thereof are improved. It is possible to provide a photoconductor for electrophotography.

Claims (6)

[Claims] 1. A conductive support having at least two layers of a charge transfer layer and a charge generation layer, wherein the charge generation layer further contains one or more charge generation agents and an electropolymer. A photoconductor for electrophotography. 2. The electrophotographic photosensitive member according to claim 1, wherein the electropolymer is a 5-membered heterocyclic compound having a structure represented by the general formula (1). [Chemical 1] 3. The electrophotographic photoconductor according to claim 1, wherein the anion in the electropolymer represented by the chemical formula 1 is an aromatic anion. 4. The electrophotographic photoreceptor according to claim 3, wherein the aromatic anion is any of alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, alkylbenzene carboxylic acid, and alkylnaphthalene carboxylic acid. 5. The electrophotographic photoconductor according to claim 1, wherein the electropolymer is in an oligomer state. 6. The electrophotographic photoreceptor according to claim 1, wherein a phthalocyanine compound is used as a charge generating agent in the charge generating layer.