JPH0572777A - Electrophotographic sensitive material - 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] An electrolyte polymer was prepared in a solution of propylene carbonate using pyrrol as a monomer and sodium toluenesulfonate as an electrolyte, and the solid substance of the electrolyte polymer was pulverized into a fine powder. This powder is mixed with a solution prepared by dissolving X-type phthalocyanine and polyester in tetrahydrofuran using polyester as a binder resin, and subjected to dispersion treatment to obtain a photoreceptor. The addition of the electrolytic polymer can improve the sensitivity and the stability.

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 promoted.

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.

Generally, in the double-layer structure, the CG layer is applied with a thickness of about 1 micron in order to improve the sensitivity, while the CT layer is
The layer is applied with a thickness of 10 to 20 microns. At this time, because of its strength, printing durability, etc., the CG layer is
The T layer is usually 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, so that the double-layered photosensitive member is of the negative charging type.

However, in such a negative charging system,
There are problems that (1) oxygen in the air becomes ozone due to the negative charge used for charging, (2) charging is unstable, and (3) the surface of the drum is easily affected. Not only is ozone harmful to the human body, it often reacts with the photoreceptor to shorten the life of the photoreceptor. Further, the instability of charging often causes deterioration of image quality, and the great influence of the drum surface requires mirror finishing or undercoating of the drum, which leads to improvement of manufacturing cost. Further, in such a two-layer system, there are problems that (4) the manufacturing process is complicated and the yield is deteriorated, and (5) the stability thereof becomes a problem due to peeling between layers. Recently, some organic photoreceptors (OPC) having a single layer structure have been proposed. We have already applied for a patent for a single-layer type organic photoconductor consisting only of X-type phthalocyanine and a binder resin, and further improvement in the stability of repeating charging and discharging and the photosensitivity is required.

[0009]

As a single-layer type organic photoconductor, one having only a binder resin and phthalocyanine has been already known, but the initial charge level is lowered by repeated tests of charging and photo-erasing. It was known that the phenomenon such as doing. Examples of the phthalocyanine include β-type metal-free phthalocyanine and copper phthalocyanine.

There is also known an example in which a charge transfer material other than phthalocyanine is added as a single-layer type structure to improve the sensitivity, but the characteristics also deteriorate in repeated tests.

In view of the above conventional problems, the object of the present invention is to:
It is an object of the present invention to provide a composition in which the stability of a single-layer type organic photoreceptor is improved as well as the photosensitivity.

[0012]

The technical means of the present invention for achieving the above object is to add an electrolytic polymer to an organic photoreceptor having a binder resin and an X-type metal-free phthalocyanine as a basic component. Electrophotographic photoconductor.

[0013]

The present inventors have found that an organic photoconductor formed by adding an electrolytic polymer to a specific phthalocyanine together with a binder resin exhibits very excellent electrophotographic characteristics including stability. As the phthalocyanine, the X-type metal-free phthalocyanine exhibited excellent characteristics unlike any other. When an organic substance known as a charge transfer material was added thereto, most of them were added, and the photosensitive characteristics were deteriorated by repeated tests. However, when the electrolytic polymer was added, the characteristics were improved.

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, alkylbenzene sulfonic acid, alkylbenzene carboxylic acid, alkylnaphthalene sulfonic 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.

In many organic photoreceptors, stability is generally deteriorated when additives are added to improve the sensitivity, but the present invention selects a composition material for a particular photoreceptor. As a result, not only sensitivity characteristics but also repeated stability, image characteristics, and printing durability were obtained.

[0017]

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 polyester as a binder resin, this powder was mixed with a solution prepared by dissolving X-type phthalocyanine and polyester in tetrahydrofuran at a weight ratio of 1: 4 at a ratio of 10 wt% with respect to X-type phthalocyanine, and further mixed. The dispersion treatment was sufficiently performed. At the same time, for comparison, a solution containing no electropolymer was also prepared. The two solutions were applied onto an Al substrate so as to have a film thickness of 20 μm, to prepare a single-layer type photoreceptor.

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 sensitivity is improved and the stability is improved by the addition of the rubber.

(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. Polycarbonate was used as the binder resin, and X-type phthalocyanine and polycarbonate were mixed at a ratio of 1: 5 to T.
Dispersion treatment was performed using an HF solvent. A solution in which 30 wt% of polythiophene was added to the X-type phthalocyanine was prepared. The solution was applied onto an Al substrate so that the film thickness was about 20 μm. The same experiment as in Example 1 was performed on these samples. The results are shown in (Table 2).

[0023]

[Table 2]

As can be seen from these results, it can be seen that the photosensitivity and the repeating stability are improved by adding polythiophene.

As the electropolymer of the present invention, it was confirmed that a 5-membered heterocyclic compound having the general formula shown in (Chemical Formula 2) below is preferable.

[0026]

[Chemical 2]

[0027]

INDUSTRIAL APPLICABILITY As described above, the present invention is an excellent electrophotographic apparatus in which the photosensitivity and the stability thereof are improved by further adding the electrolytic polymer to the photoreceptor composed of the binder resin and the metal-free X-type phthalocyanine. Photoconductor can be provided.

Claims (5)

[Claims] 1. A photoconductor for electrophotography, characterized in that a single-layer type positive charging type organic photoconductor basically composed of a binder resin and an X-type phthalocyanine contains an electropolymer. . 2. The electrophotographic photoreceptor according to claim 1, wherein the electropolymer comprises 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.