JPH0157782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoreceptor for electrophotography, and more specifically, a selenium or selenium-based photoreceptor for electrophotography using an Al substrate on which a boehmite film, which is a type of aluminum oxide, is formed on the surface as a conductive substrate. Regarding photoreceptors.

Selenium or selenium-based photoreceptors are made of Se on a conductive substrate (conductive substrate) such as Al, In ₂ O ₃ or stainless steel.
Alternatively, a vapor deposited layer (photoconductive layer) made of a selenium alloy is provided.

By the way, in the production of such photoreceptors, the surface of the conductive substrate is often provided with minute irregularities in order to improve the adhesion between the conductive substrate and the photoconductive layer, the strength of the photoconductive layer, etc. . It has also been confirmed that when these fine irregularities are reflected on the surface of the photoconductive layer, transfer separation and edge effects are brought about on the photoreceptor.

However, even though it is advantageous to form fine irregularities on the surface of the photoreceptor (the surface of the photoconductive layer), the size, depth, etc. of the irregularities must be naturally limited, and therefore selenium or selenium-based When manufacturing photoreceptors, the reality is that various treatments are performed on the surface of the conductive substrate or photoconductive layer. For example, after bubbling, electropolishing, or diamond polishing the surface of the substrate, a photoconductive layer is deposited thereon and the surface of the deposited layer is treated with a silane coupling agent. No. 49-39425, Japanese Patent Publication No. 1973-
109732, etc.), honing the substrate surface (Japanese Patent Application Laid-open No. 58954/1983), polishing the surface of the substrate with fine metal oxide powder (Japanese Patent Publication No. 13979/1987), and superfinishing the conductor surface. For example, the surface is roughened by processing (Japanese Unexamined Patent Publication No. 13424/1983). Note that when the substrate surface is treated in these treatments, the substrate surface is generally subjected to a degreasing treatment prior to the next vapor deposition. In addition to these treatments, it has also been proposed to further vapor deposit a pure conductive metal on the surface of the substrate to make it conductive.

The reason why such a treatment is performed is to make the shape of the fine irregularities formed on the surface of the photoreceptor ideal or close to the ideal. However, in reality, it is difficult to achieve the desired shape, and there are quite a few irregularities on the surface of the photoreceptor. Usually, a large protrusion appears. These protrusions cause various problems in the electrophotographic imaging process. To name a few, large or numerous protrusions formed on the surface of the photoreceptor can (1) directly cause uneven charging of the latent image, or mechanically cause uneven toner adhesion during development; (2) In the case of electrophotography that uses a cleaning method using a blade, the blade is gradually scraped by the protrusions on the surface of the photoreceptor;
The cleaning performance is extremely deteriorated, which ultimately leads to poor cleaning and the appearance of many so-called black lines in the copied image.

As described above, unnecessary protrusions formed on the surface of the photoreceptor have a very negative effect on the electrophotographic image forming process, but these protrusions are mainly formed during the vacuum deposition of the photoconductive layer. The causes of this protrusion have so far been thought to be the unevenness of the substrate surface, the adhesion of dust, etc. In order to avoid this, various polishing methods such as those mentioned above, percolene cleaning, etching, water washing, etc. have been used. Countermeasures have been taken. Furthermore, bumping phenomenon due to the heat of selenium or selenium-based alloys in the vapor deposition source during vapor deposition is considered to be one of the causes of protrusion generation, and measures to prevent this bumping phenomenon have been proposed. However, even if all of these are satisfied, the reality is that it is still not possible to completely or nearly completely prevent the occurrence of protrusions.

The present inventors have conducted numerous studies and studies on the occurrence of these protrusions, and have found that these protrusions occur particularly on the surface of aluminum substrates (including plate-shaped, drum-shaped, and belt-shaped ones) during the initial stage of vapor deposition. It was found that this is due to variations in physicochemical interface phenomena with deposited substances such as selenium or selenium-based alloys.
The present invention has been made based on this knowledge.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor in which the formation of protrusions on the surface of the photoreceptor is prevented by eliminating variations in the physicochemical operations at the vapor deposition interface. Another object of the present invention is to make the wettability and thermal conductivity of the surface uniform by making the composition of the surface of the Al base uniform, even if there are some large irregularities on the surface of the Al base. As a result, it is an object of the present invention to provide an electrophotographic photoreceptor in which a deposited film is formed in which the number of protrusions is extremely small even if they occur. Still another object of the present invention is to provide an electrophotographic photoreceptor that can increase the latitude for other base surface treatments that have been conventionally performed during the manufacturing process.

That is, in the electrophotographic photoreceptor of the present invention, at least the image area portion of the surface of the aluminum substrate has a thickness of approximately
It is characterized in that a photoconductive layer made of selenium or a selenium alloy is provided on the boehmite film of a conductive substrate on which a boehmite film of 1000 Å or more is formed.

The present invention will be explained in more detail below. The electrophotographic photoreceptor of the present invention uses a conductive substrate in which a specific aluminum oxide film of a constant thickness is intentionally formed on the surface of an aluminum substrate. be. However, in general, an oxide film is often formed partially on the Al surface, but in such a state, as mentioned above, the variation in the surface composition (that is, the variation in the surface physical properties) is rather large. On the contrary, it is in a state where protrusions are likely to occur. In addition, in order to achieve a uniform composition of the substrate, it is possible to deposit the photoconductive layer after depositing pure metal Al, but in such a case, the interfacial adhesion of the photoconductive layer would be extremely poor and it would be easy to It can also be seen as it peels off.

Therefore, in the present invention, a more uniform oxide film is formed on the surface of the Al substrate. In the present invention, a boehmite (Al.O.OH) film is used as the aluminum oxide film. This is because, as a result of various experiments, it has become clear that among various aluminum oxide films, a boehmite film is particularly effective. However, the object of the present invention can be achieved even if this boehmite film is not necessarily obtained in a pure form. The formation of the boehmite film is thought to be based on the reaction formula: 2Al+4H ₂ O=2Al.O.OH+3H ₂ . This reaction is
It is preferable to do this under warm water of 60℃ or higher. Furthermore, it is also effective to add, for example, an appropriate amount of sodium aluminate to hot water in order to accelerate this reaction.

The thickness of the boehmite film is approximately 1000 Å or more, preferably 1000 Å to 1 μm. If it is thinner than 1000Å, it will be difficult to form a uniform boehmite film;
Even if the thickness becomes thicker than 1 μm, the effect is not significantly increased.

A photoconductive layer is provided on the boehmite film of the conductive substrate as described above. Specifically, the photoconductive layer is Se, Se-Te, Se-As, Se-Te-As, Se-
It is made of selenium or selenium-based alloys such as Te-Cl. The thickness of the photoconductive layer is approximately 30 to 60 μm.

In order to actually manufacture the photoreceptor of the present invention, the surface of the Al substrate is polished and then washed, a boehmite film is formed on this to form a conductive substrate, and then a conventional method is applied on the boehmite film of this conductive substrate. Therefore, the photoconductive layer may be provided by vapor depositing Se or a Se-based alloy. In this manufacturing process, to form a boehmite film, the cleaned Al substrate may be immersed in hot water maintained at 60° C. or higher in advance so that the film has a thickness of 1000 Å to 1 μm.
The water here is preferably pure water such as ion-exchanged water, and has a resistance of 0.1 megohm-cm or more, preferably 1 megohm-cm or more.

Although sufficient and detailed studies have not yet been conducted as to whether the photoreceptor of the present invention produced as described above will produce good results in the electrophotographic imaging process, it is possible to form a uniform boehmite film on the surface of the Al substrate. As a result of this formation, even if there are quite large irregularities on the surface of the Al substrate, these become considerably smaller, making the surface composition uniform, and the wettability and thermal conductivity of the conductive substrate surface are uniform and good. This is thought to be due to the formation of a deposited film without protrusions. Furthermore, according to the photoreceptor of the present invention, the surface of the conductive substrate and the vapor deposited layer were well compatible, so that the vapor deposited layer (photoconductive layer)
Another effect is that the inconvenience of peeling off from the conductive substrate is no longer observed.

Next, examples and comparative examples will be shown.

Example 1 After polishing the surface of an aluminum drum (120φ×400mm), it was washed with perclean for 2 minutes. Furthermore, the water washing was repeated twice (each time for 1 minute). Then,
This was immersed in ion-exchanged water maintained at 80℃ for 10 minutes to form a layer of 1000Å to 1μm on the Al drum surface.
A boehmite film with a range of thickness was formed.

After drying, this drum-shaped conductive substrate was set in a vacuum evaporator and the substrate temperature was lowered under a reduced pressure of 10 ^-5 torr.
As ₂ Se ₃ was maintained at 190℃ and the evaporation source temperature was 400℃.
was deposited for 30 minutes to provide a photoconductive layer approximately 50 μm thick on the conductive substrate.

When the surface of the electrophotographic photoreceptor manufactured in this way was examined using a microscope and visual observation, it was found that
No protrusions larger than 20 μm were observed on the entire surface of the photoreceptor.

Example 2 Example except that instead of being immersed in ion-exchanged water maintained at 80°C for 10 minutes, an aqueous solution prepared by adding sodium aluminate (500 mg/) to the ion-exchanged water was maintained at 70°C and immersed for 8 minutes. An electrophotographic photoreceptor was produced in the same manner as in Example 1.

When we investigated the condition of the protrusions on the surface of the photoreceptor, we found that
No particles larger than 20 μm were observed on the entire surface of the photoreceptor.

Comparative Example An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the formation of a boehmite film by immersion in ion-exchanged water was omitted.

When we investigated the condition of the protrusions on the surface of the photoreceptor, we found that
It was confirmed that 50 or more protrusions of 20 μm or more were present on the entire surface of the photoreceptor.

Claims (1)

[Claims] 1. A photoconductive layer made of selenium or a selenium alloy is provided on the boehmite film of a conductive substrate in which a boehmite film with a thickness of 1000 Å or more is formed on at least the image area portion of the aluminum substrate surface. Photoreceptor for electrophotography.