JPH01138564A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a high quality image free from black spots by anodically oxidizing the surface of an electrically conductive Al support with an electrolytic soln. having dissolving action and an electrolytic soln. having no dissolving action in order and by forming a photosensitive layer on the surface of the support. CONSTITUTION:The surface of an electrically conductive Al support is anodically oxidized with an electrolytic soln. having dissolving action and an electrolytic soln. having no dissolving action in order and a photosensitive layer is formed on the surface of the support. The electrolytic soln. having dissolving action contains at least one among sulfuric acid, chromic acid and phosphoric acid and the electrolytic soln. having no dissolving action contains at least one among borate, tartrate, adipate and malate. The rugged surface of the support is first smoothened with the electrolytic soln. having dissolving action and then a dense film having high electric insulating property is formed with the electrolytic soln. having no dissolving action. The implantation of electric charges from the support is suppressed, the resulting sensitive body can be set in a laser printer and a high quality image free from black spots can be obtd.

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 electrophotographic printers that imagewise line scan a laser beam. It is related to.

2. Description of the Related Art 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 cliff. This method differs from the method previously used in electrostatic copying machines, in that it attaches toner to the exposed areas with a low potential, causing uneven charging, interference fringes, and black 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 sit layer by mixing a conductive material and a resin. has been completed. (For example, Japanese Patent Laid-Open No. 61-240247).

Problems to be Solved by the Invention However, in the method of roughening the surface, the effect that appears 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 conditions. 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 selection of solvent for the photosensitive layer provided on the conductive layer, or the adhesion with the photosensitive layer may deteriorate, which may affect the repeatability of the photoreceptor. The former is mainly found in thermoplastic resins, and the latter is found in thermosetting resins.
As mentioned above, there were various problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides that the surface of a conductive support made of aluminum is anodized using at least an electrolytic solution having a dissolving action and an electrolytic solution having no dissolving action. The present invention provides an electrophotographic window illuminator characterized in that it is treated in a process consisting of anodization and a photosensitive layer is provided on the surface.

As a result of research, the inventors found that porous aluminum oxide (A1203) obtained by anodic oxidation using a dissolving electrolyte such as sulfuric acid or oxalic acid cannot form a sufficiently dense film. found that although it is effective in terms of surface homogenization, it is extremely ineffective in terms of electrical barrier properties. Furthermore, the dense film obtained by anodic oxidation using a non-dissolving electrolyte such as borate or adipate cannot sufficiently cover the unevenness of the surface, and the defects of the substrate themselves appear on the image. I found out that it can be put away.

In the latter case, it is known that the film thickness is 14 angstroms per 1 cm of applied voltage during anodic oxidation treatment, and it is thought that the surface irregularities can be sufficiently covered by increasing the voltage itself. However, it is believed that the barrier properties are too high and the repeatability of the photoreceptor deteriorates.The inventors successfully combined these advantages and succeeded in removing defects on the surface of the substrate. That is, the unevenness of the substrate is removed by a porous film of several microns and a barrier film of several hundred angstroms, and furthermore, the barrier film is promoted by a secondary treatment to improve electrical insulation. When a photosensitive layer was formed on this film, an extremely good image without interference fringes or black spots was obtained.

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

(Example 1) In order to form a porous film, aluminum may be anodized in an electrolyte having a dissolving action such as sulfuric acid, chromic acid phosphoric acid, or the like. In this example, a sulfuric acid solution was used. This treatment creates a porous film of 2 μm on the aluminum surface.
m, 4 μm, and 8 μm (hereinafter, this porous film will be referred to as a porous layer). At the same time, a dense film also grows, forming about 150 angstroms under the porous layer. After this treatment, water conduction treatment may be performed to seal the pores.Water conduction treatment is a trihydrate treatment called barrierite, which has a different number of hydrates depending on the treatment temperature, and a monohydrate treatment, called boehmite. There is. Either of these may be used, but in this example, one treated with boehmite was used. After this secondary treatment, a secondary treatment is performed in an electrolytic solution that has no melting action.

As the solution for the secondary treatment, borate, tartrate, adipate 1, malate, etc. can be used, and in this example, adipate was used. ! @Dissolve adipic acid in water and add ammonia to this solution to adjust t pH to 5.5. It may be adjusted by adding ammonium adipate to adipic acid. An aluminum drum, which will serve as the base material of the photoreceptor, is immersed in this solution and used as an anode. After maintaining the solution temperature at 60 degrees and performing constant current chemical formation at a chemical formation voltage of 25 to 350 V, the chemical formation is continued while maintaining the voltage. Leakage current is 30μ
Continued until A/- was reached. The time required for the treatment varies depending on the thickness of the porous layer during the primary treatment and the formation voltage during the secondary treatment, and the thicker the porous layer and the higher the formation voltage, the longer it takes.

Porous layer is 4μm, formation voltage is 50V, 60φX'
When only the outer surface of the 338 ms drum was processed, the time required for secondary processing was approximately 3 to 10 minutes. A photosensitive layer is provided on the film formed as described above. The photosensitive layer may be made of, for example, chalcogenides such as selenium, selenium-tellurium, selenium-arsenic, selenium-arsenic-tellurium, inorganic compounds such as amorphous silicon or cadmium sulfide, or organic photoconductive dyes and pigments such as azo-based, perylene-based, Examples include cyanine-based and phthalocyanine-based materials. In the phthalocyanine series, in addition to pigments with various crystal forms such as α, β, γ, ε, and τ, there are also metal phthalocyanines with metal coordination at the center and metal-free phthalocyanines with no coordination.
The photosensitive layer was of a functionally separated type, and the charge generation layer was prepared by mixing τ-type metal-free phthalocyanine and butyral resin (manufactured by Sekisui Chemical Co., Ltd., trade name Nisrex Bl(-3) in a weight ratio of 4:3. was dispersed with a solvent such as tetrahydrofuran, and then formed into a film with a thickness of approximately 0.3 μm.In order to improve adhesion, polyamide (manufactured by Toshi Co., Ltd., trade name CM-) was applied on the base material (on the film). 8000) to about 0.
After coating as a 3 μm adhesive layer, a charge generating layer was coated.

The charge transport layer was prepared by mixing a hydrazone compound with a polycarbonate resin. As a hydrazone compound, 1-
Phenyl-1,2,3,4-tetrahydroquinoline-6
-Carpoxyaldehyde 1', 1'-diphenylhydrazone is mixed in a 1:1 weight ratio with a polycarbonate resin (Mitsubishi Chemical Industries, Ltd., trade name Novarefx 7030A or Bayer Corporation, Macrophor N), and a solvent such as methylene chloride is used. A film was formed on the charge generation layer.

The film thickness was 17 to 20 μm. The photosensitive drum produced in this way is printed on a laser printer (our product name: FPr,
-300) and compared the amount of black spots when it was solid.

For comparison, we simultaneously examined cases in which the aluminum base material was not subjected to secondary treatment and cases in which only secondary treatment was performed.

Black spots are especially likely to occur at high temperatures. The results are shown in the table below, and the measurements were carried out in an environment of 33 degrees and relative humidity of 80%.

When there are about 10 black spots on the surface per 1 d, it looks like fog, and the quality of the image is significantly degraded. As can be seen from the above table, the secondary treatment of the present invention was shown to be extremely effective in removing black spots. It has also become clear that this secondary treatment is effective regardless of the degree of primary treatment.

However, it was not possible to obtain a sufficient effect with only secondary processing, and black spots remained on the image. Although various causes of black spots can be considered, it is believed that the main cause is large charge injection from the base metal to the photosensitive layer. When the layer is used, the surface of the photoreceptor is negatively charged. In this case, the charge transport layer has almost no ability to transport negative charges, and charge attenuation is caused by charge injection from the charge generation layer or charge injection from the base material. In this case, hole injection is particularly unfavorable. That is, this problem becomes noticeable when the charge generation layer is too thick or when there is no blocking property between the base material and the charge generation layer. An example of the former is that the base material has irregularities, and the charge generation layer aggregates in these areas, causing extremely rapid dark decay and causing black spots.

Of course, if there is aggregation in the charge generation layer itself, this is out of the question. As an example of the latter, when the work functions of the phthalocyanine and the metal are close or large, metals such as gold and copper are not preferred as the base material. When aluminum contains these metals, charge injection occurs only in those parts, causing black spots. Usually, in order to eliminate these problems, a highly insulating film is provided between the base material and the charge generation layer. Polyamide, which is also used in this embodiment, is also used for this purpose. However, this film cannot sufficiently cover the irregularities of the base material.
Furthermore, it lacks stability against humidity and often fails to achieve its purpose.

As mentioned above, secondary treatment (
Chemical conversion treatment) provided a film with high electrical barrier properties to prevent black spots when the surface was completely 0, and was effective in suppressing charge injection from the base material. In addition, primary treatment using an electrolytic solution that has a dissolving action was effective in removing irregularities from the base material.

(Example 2) After a primary treatment with sulfuric acid to form a porous layer of 4 μm and a sealing treatment to form boehmite, the material is further treated with an electrolytic solution containing a nickel salt.

After this, secondary treatment is performed as in Example 1. Even with this, a good image without black spots was obtained. However, the time required for the secondary treatment is three to four times longer than that in the first embodiment.

Effects of the Invention In summary, the present invention anodizes the surface of aluminum using an electrolytic solution that has a dissolving action, covers the unevenness of the surface, and then anodizes it using an electrolytic solution that does not have a dissolving action. As a result, we have obtained an electrophotographic photoreceptor that obtains a dense film with high electrical insulation properties, suppresses charge injection from the base material, and produces good images without black spots so that it can be installed in laser printers. It is an invention.

Claims (1)

[Scope of Claims] (1) The surface of a conductive support made of aluminum is treated in a step consisting of at least anodizing with an electrolytic solution having a dissolving action and anodizing with an electrolytic solution having no dissolving action, and the surface of the conductive support is An electrophotographic photoreceptor comprising a photosensitive layer. (2) The electrophotographic photoreceptor according to claim (1), wherein the electrolytic solution having a dissolving action is composed of an electrolytic solution containing at least one of sulfuric acid and chromic acid phosphoric acid. (3) Electrolytes without dissolving action include borates,
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is composed of an electrolytic solution containing at least one of tartrate, adipate, and malate. (4) Claim No. 1, characterized in that the photosensitive layer contains a τ-type metal-free phthalocyanine and a hydrazone compound.
) The electrophotographic photoreceptor described in item 2.