JPH02173757A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a film having a high electric blocking property and to suppress the charge implantation from an aluminum base material as well as to obtain good images which are free from black spots and fogging by anodizing the surface of the base material and confining the content of the chlorine contained in this film to <=0.05% of all these constituting elements. CONSTITUTION:The causes for lacking of the stability by even the photosensitive drum after a surface treatment, such as generation of small spotty image noises in a white ground part and degradation of electrostatic chargeability, lie in the stains sticking to the aluminum or the surface of the anodized film on the aluminum surface, more particularly the stains by chlorides. A charge generating layer for implanting positive charges to a charge transfer layer is, thereupon, provided on the surface oxide layer formed by oxidizing the surface of the aluminum. The charge transfer layer is laminated on this charge generating layer and the content of the chloride in the surface oxide layer is confined to <=0.05wt.% of all the constituting elements. The electrophotographic sensitive body which is free from the fogging and black spots and has mass productivity is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electronic copying machines, printers, and facsimile machines, and particularly relates to an electrophotographic photoreceptor suitable for an electrophotographic printer that uses a laser beam to imagewise line scan the image. be.

Conventional Techniques In recent years, the development of electrophotographic printers using laser beams has been remarkable, but the reversal development method has become mainstream from the viewpoint of copying speed and resolution. This method differs from the method previously used in electrostatic copying machines, in that it attaches toner to the exposed areas with low potential, causing uneven charging, interference fringes, and FA spots on the photoreceptor substrate. This resulted in an extremely sensitive understanding of the impact. To solve this problem, there are ways to roughen the surface, provide an insulating resin between the conductive substrate and the photosensitive layer, or create a conductive layer by mixing a new conductive material and resin. has been completed. Alternatively, there are reports that charge injection into the photosensitive layer is prevented by a blocking effect. (For example, Japanese Patent Application Laid-Open No. 61-24024
Publication No. 7, JP-A-63116160, JP-A-63
(Publication No. 116165) Problems to be Solved by the Invention However, in the method of roughening the surface, the effect appearing on the image differs depending on the degree of roughening. That is, if the degree of interference is weak, moire-like interference fringes will appear on the image, and if it is too strong, image defects will appear. Therefore, it is necessary to control the roughness within a certain range, which poses a practical problem. Furthermore, when the surface is roughened by cutting, periodic scraping causes interference fringes.

When an insulating resin is provided between the conductive substrate and the photosensitive layer, the resin itself is highly dependent on the environment, and in particular, it cannot be expected to be effective in covering defects in the conductive substrate under high temperature and high humidity. In this case, a thick film can be used to solve the problem, but on the other hand, it leads to deterioration of characteristics at low temperatures and low humidity.In order to solve these problems, studies have been made to create a conductive layer by mixing a conductive material and a resin. Environmentally stable conductive layers are being developed. However, in this case, depending on the type of resin used, there may be restrictions on the solvent selection for the photosensitive layer provided on the conductive layer, or the contactability with the photosensitive layer may deteriorate, which may not affect the repeatability of the photoreceptor. . The former is mainly seen in thermoplastic resins, and the latter is found in thermosetting resins. Furthermore, many patents that provide a layer of anodic oxidation on the aluminum surface do not reveal the root cause of the problem, but merely patent conditions suitable for obtaining good results. For this reason, it lacked quality stability and was insufficient for mass production as an industrial product. As mentioned above, there were various problems.

Means for Solving the Problems In order to solve the above problems, the present invention provides a charge generation layer that injects positive charges into the charge transport layer on a surface oxidation layer obtained by oxidizing the surface of aluminum, and the main 111 generation layer The present invention provides an electrophotographic photoreceptor, on which a charge transport layer is laminated, and the surface oxidized layer has a chlorine content of 0.05 wt% or less based on all constituent elements.

As a result of research, the inventors found that porous aluminum oxide (A120.) obtained by anodizing using an electrolyte with a dissolving effect such as sulfuric acid or oxalic acid can be produced by surface etching treatment prior to this treatment. It has been confirmed that this method is effective in removing dissimilar metals, so-called crystallized substances, which are difficult to penetrate into the aluminum existing on the aluminum surface, and in improving surface bronking properties. However, even with the surface-treated photoreceptor drum, it lacked stability, such as small spot-like image noise occurring in the white background area or a decrease in charging performance. Therefore, as a result of further exploration, the inventors found that
It has been found that this is caused by dirt, particularly chloride, adhering to the aluminum or the surface of the anodic oxide film on the aluminum surface. It has been found that when there is no anodic oxide film on the aluminum surface, crystallized substances are detached during cleaning, especially during ultrasonic cleaning, and chloride remains in the pores.

Further, when the charge generation layer is mainly of the hole transfer type, the chloride removes electrons from the charge generation layer, creates holes, increases the conductivity, and reduces the chargeability. This is,
Local occurrences are the cause of small black spots in the image, and chloride in the holes becomes the nucleus of the black 9 [dots].

Example An embodiment of the present invention will be described in detail below.

To form a porous film, aluminum may be anodized in a dissolving electrolyte such as sulfuric acid, chromic acid, or phosphoric acid. In this example, a sulfuric acid solution was used. The aluminum surface oxidation treatment process includes degreasing the cutting oil after drum cutting, etching with caustic soda, neutralization,
Electrolyte treatment.

The steps include sealing, washing with pure water, and drying. As the aluminum alloy, a JIS6063 alloy is used.

Table 1 shows the ratio of elements other than aluminum in the aluminum alloy used in the experiment.

Table 1 (Unit: wt%) This alloy has a lower iron element content than JI53003 etc., and the iron element is better removed from the surface during etching with caustic soda. Elimination of this iron element is important for obtaining a good oxide film in the anodizing process. Table 2 shows that the desorption state of iron element changes depending on the etching temperature. The analysis was performed using fluorescent X-rays.

Table 2 (wt%) Sealing after anodizing is necessary to keep the product stable, and care must be taken at this time as well. Seal the hole with two Sokel salts (
For example, Tomp Seal L- manufactured by Okuno Pharmaceutical Co., Ltd.
100 etc.) is used. The anodic oxide skin 112 film j7 after the sealing treatment had a thickness of 6±1.5 μm. If chlorine or the like gets mixed in during sealing, it will appear as a fog on the image. This is because, as shown earlier, chlorine (chloride) extracts electrons from the phthalocyanine, which is the charge generation layer, and generates holes inside the charge generation layer, which are injected into the charge transport layer and increase the surface charge. This is thought to be to cancel it out. The effect of this chloride will be experimentally investigated. First, chloride is formed on the surface of the base material.

Wash the aluminum substrate with I.lichlorethylene.

Whether or not chloride has been formed on the surface of the substrate is confirmed by subjecting the surface of the substrate to fluorescent X-ray analysis. FIG. 1 is a chart comparing the chlorine strength before and after washing the substrate. It can be confirmed that the strength of chlorine is increased by washing with trichlorethylene.

A charge generation layer (a mixture of τ-type metal-free phthalocyanine and butyral resin) is applied to a thickness of 0.55 μm on top of this cleaning base. Figure 2 shows the surface potential and a residual current plotted from the dark decay after charging of this sample. For comparison, the leakage current of a sample without cleaning the base material is also plotted.

In the case where the base material was washed with trichlorethylene, the contact between the aluminum and the charge generation layer was resistance contact, indicating a situation where charge injection from the base material was likely to occur. On the other hand, those without washing show blocking contact (shontoky contact) with respect to the positive ratio. That is, the acceptor effect of chloride facilitates injection from the base material, and the injected charges are injected into the charge transport layer, lowering the surface potential. This appears as a fog or locally occurs as black spots (image noise).

A photosensitive layer is formed on the substrate carefully prepared in this manner. In this example, the photosensitive layer is of a functionally separated type, and the charge generation layer is made of τ-type metal-free phthalocyanine and butyral resin (manufactured by Sekisui Chemical Co., Ltd., trade name Nisrex B H-3).
The mixture was mixed in a weight ratio of 4:3, mixed with a solvent such as tetrahydrofuran for 11 minutes, and then used to form a film with a thickness of about 0.3 μm. For the purpose of improving adhesion, polyamide (manufactured by Toshi Co., Ltd., product name: CM) is applied to the substrate (film).
8000) was applied as an adhesive layer of about 0.3 μm, and then the charge generation layer was applied. The charge transport layer was prepared by mixing a hydrazone compound with a polycarbonate resin. Hydrazone compounds include 1-phenyl-1,2,3,4tetravitroquinoline-6-carboxydialdehytol, 1-
Diphenylhydrazone is mixed with a polycarbonate resin (product name Tuvalex 7030A manufactured by Mitsubishi Chemical Industries, Ltd. or Macropol N manufactured by Bayer) at a weight ratio of 1:1 and dissolved in a solvent such as methylene chloride, followed by a charge generation layer. A film was formed on top. The film thickness was 17 to 20 μm. The photosensitive drum made in this way is printed on a laser printer (Matsushita?
It was mounted on a product FPL-300 (manufactured by Iliki Sangyo Co., Ltd.), and the black spots were compared when it reached zero. For comparison, the anodic oxide film used as equipment contains 0.12 wL of chlorine among all constituent elements.
Table 3 summarizes the cases where % is included.

Table 3 When the number of black spots is about 10 per c4, it looks like fog and significantly reduces the quality of the image. Figure 3 shows the repetition characteristics through each environment. The charging potential, n-front potential, and residual potential, which represent electrophotographic characteristics, are stable in each environment, providing a good photoreceptor.

In laminated electrophotographic photoreceptors that have a charge generation layer that injects positive charges into the charge transport layer, such as costumes, an anodized film is formed on the surface of the aluminum material, and the amount of chlorine contained in the film is reduced by reducing the amount of chlorine contained in the film. By suppressing the content to 0.05 wt% or less, it is possible to create an electrophotographic photoreceptor that is free from fog and black spots and can be mass-produced.

Effects of the Invention In short, the present invention anodicizes the surface of an aluminum base material using an electrolytic solution having a dissolving action, and reduces the amount of chlorine contained in the film by a total of fl! By controlling the content to 0.05 wt% or less in the constituent elements, a film with high electrical blocking properties can be obtained, suppressing charge injection from the base material, and producing a good image without black spots or fog, which is suitable for use in laser printers. This is an extremely useful invention that provides an electrophotographic photoreceptor that is highly mass-producible.

[Brief explanation of the drawing]

Figure 1 is a fluorescent X-ray analysis chart of an aluminum base material in an example of the present invention, Figure 2 is a graph showing the relationship between surface potential and leakage current in the dark, and Figure 3 is an electrophotograph according to the present invention. This is a characteristic diagram showing the electrostatic repetition characteristics of a photoreceptor. Name of the agent: Patent attorney Shigetaka Awano.

Claims (5)

[Claims] (1) On the surface oxidized layer of the aluminum surface,
A charge generation layer for injecting positive charges into the charge transport layer is provided, the charge transport layer is laminated on the charge generation layer, and the chlorine content in the surface oxidation layer is 0.05 wt% or less of all constituent elements. An electrophotographic photoreceptor featuring: (2) The electrophotographic photoreceptor according to claim (1), wherein the surface oxidation layer is anodized with an electrolyte having a dissolving effect. (3) The electrophotographic photoreceptor according to claim (2), wherein the electrolytic solution having a dissolving action is composed of an electrolytic solution containing at least one of sulfuric acid, chromic acid, and phosphoric acid. (4) The electrophotographic photoreceptor according to claim (2), wherein the surface oxidized layer is sealed with a sealing liquid containing a nickel salt. (5) The electrophotographic photoreceptor according to claim (1), wherein the charge generation layer is a charge generation layer containing a τ-type metal-free phthalocyanine.