JP2639110B2 - Manufacturing method of electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic photosensitive member, and more particularly, to a method for manufacturing an electrophotographic photosensitive member having a selenium alloy photosensitive layer.

2. Description of the Related Art It is known to use a selenium or selenium alloy vapor-deposited film as a photoconductive layer for an electrophotographic photoreceptor, a solid-state image pickup tube, an optical sensor, or the like. The deposited film of selenium or selenium alloy,
It is common to heat the deposition material in a vacuum and adhere the vapor to the substrate to form.

However, when a selenium alloy is deposited by such a vacuum deposition method, due to the difference in vapor pressure of the element added to selenium, the alloy composition ratio of the evaporation material in the film greatly changes.
There is a problem that a so-called fractionation phenomenon occurs. For example, in electrophotographic photoreceptors, conventionally, an alloy of selenium and tellurium, arsenic, etc. is often used as a typical example of an amorphous chalcogenide, but when such an alloy is heated and vapor-deposited, Since the vapor pressure of tellurium and arsenic is different from that of selenium, a phenomenon occurs in which selenium adheres more to the substrate in the early stage of the vapor deposition process, and a large amount of tellurium or arsenic adheres in the final stage. When the concentration of tellurium or arsenic in the photosensitive layer becomes high near the surface, there arises a drawback that the photosensitivity becomes extremely high or the dark potential decreases. Further, also in the manufacturing process, it is difficult to maintain the reproducibility of vapor deposition, and there is a disadvantage that the variation in photosensitivity is increased.

In order to solve these drawbacks, various methods have been proposed for improving the manufacturing process to make the concentrations of tellurium and arsenic uniform. For example, it has been proposed to co-deposit selenium and a selenium-tellurium alloy, or to provide a shutter over a selenium-tellurium evaporation source to interrupt the deposition, thereby suppressing an increase in the concentration near the surface of tellurium. I have.

Problems to be Solved by the Invention However, these conventionally proposed methods involve a complicated manufacturing apparatus, and a load is imposed on the control of vapor deposition,
Alternatively, there is a problem that the manufacturing cost is increased.

Therefore, the present invention has been made to improve the above-mentioned problems in the conventional technology.

In other words, an object of the present invention is to pre-process a selenium alloy vapor deposition raw material so that an electrophotographic photosensitive layer can be easily formed without causing fractionation of elements added to selenium without using a complicated manufacturing apparatus. It is to provide a method that can be obtained.

Means for Solving the Problems The method for producing an electrophotographic photoreceptor of the present invention comprises a first step of oxidizing the surface of a selenium alloy fine powder and depositing the oxidized selenium alloy fine powder on a conductive substrate. It comprises a second step.

 Hereinafter, the present invention will be described in detail.

In the present invention, as an additive element in the selenium alloy, As, Te, Sb, which are known as selenium sensitizing elements,
It is possible to use one or more of Bi and the like,
In particular, tellurium and arsenic are preferable, and in the case of tellurium, 40% by weight
Hereafter, in the case of arsenic, a remarkable effect is produced at 20% by weight or less. Of course, it is also possible to add another element such as halogen to give another effect.

In the present invention, the selenium alloy is used in the form of a fine powder in order to increase the surface area when performing a surface oxidation treatment. The particle size of the fine powder is at least 1 mm or less, especially 50
It is preferably not more than μm. As the selenium alloy, one originally produced as a fine powder may be used as it is, but when it is obtained as coarse particles, it may be one that has been mechanically pulverized. In this case, as a mechanical pulverizing method, a method using a grinder or a hammer mill can be used.

The oxidation treatment of the selenium alloy fine powder can be performed by various methods. For example, a method of mechanically stirring the selenium alloy fine powder in an oxygen atmosphere, and a method of blowing air or oxygen gas onto the selenium alloy powder can be effectively used.
Further, ozone which is an oxidizing gas may be used.

The selenium alloy fine powder surface-oxidized as described above can be used as it is as an evaporation source, but in consideration of ease of operation in the manufacturing process, it is compression-molded into a tablet. It is preferable to use granules by heating or granulating them by applying heat.

The vapor deposition on the conductive substrate can be performed by a conventional method. For example, when a selenium alloy is vapor-deposited on a conductive substrate by resistance heating using a vacuum vapor deposition apparatus, the selenium alloy is kept in a state in which an additive element such as tellurium or arsenic is not easily evaporated because the surface of the fine powder is oxidized. Therefore, it is considered that in the evaporation process, fractionation of tellurium, arsenic, and the like is suppressed, and only selenium does not selectively evaporate, but the entire fine particles covered with the oxide film evaporate gradually.

The electrophotographic photoreceptor obtained by the method of the present invention does not have a problem that the concentration of the added element in the vicinity of the surface is sharply increased, and can prevent abnormal light sensitivity and lower dark potential.

Examples Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 High-purity selenium (90% by weight) and high-purity tellurium (10% by weight) were placed in a quartz glass container, and heated and melted. At this time, a reducing gas (H ₂ ) was blown into the melt and stirred. Thereafter, the melt was flowed on an aluminum plate in a nitrogen gas atmosphere, and was short-cut and rapidly solidified to obtain a selenium-tellurium alloy.

The obtained selenium-tellurium alloy was pulverized in a hammer mill at a rotation speed of 5000 rpm to obtain a fine powder having an average particle size of 45 µm. Put this fine powder in a box,
Minutes and mixed and stirred.

The processed fine powder is processed into a tablet by a compression molding machine, and then vacuum-deposited on an aluminum substrate by a vacuum deposition apparatus at a degree of vacuum of 10 ^-4 Torr until a film thickness of 60 μm is formed. An electrophotographic photosensitive member having a selenium-tellurium photosensitive layer was obtained. When the tellurium concentration in the thickness direction of the photosensitive layer was determined by X-ray analysis, it was 9.8% by weight on the substrate side and 10.3% by weight on the free surface side.

When an image was formed using this electrophotographic photosensitive member by an electrophotographic process including charging, image exposure, development, and transfer steps, an image free from defects such as fog was obtained.

Comparative Example In Example 1, the selenium-tellurium alloy fine powder obtained by pulverization was processed into a tablet form by a compression molding machine as it was, and then vacuum-deposited in the same manner as in Example 1 to prepare an electrophotographic photosensitive member. did. The tellurium concentration in the thickness direction of the photosensitive layer of the obtained electrophotographic photosensitive member was 8.6% by weight on the substrate side and 11.5% by weight on the free surface side.

Example 2 In a quartz glass container, 86% by weight of high-purity selenium, 12% by weight of high-purity tellurium, and 2% by weight of high-purity arsenic were heated, melted and stirred, and then selenium alloy was obtained in the same manner as in Example 1. A fine powder was obtained. The obtained selenium alloy fine powder was put into a stirrer, and air was replaced with oxygen gas. Then, the powder was rotated with the stirrer for 10 minutes to bring the fine powder surface into contact with oxygen gas. The processed fine powder was processed into a tablet, and then vacuum-deposited in the same manner as in Example 1 to obtain an electrophotographic photosensitive member. When the tellurium / arsenic concentration in the thickness direction of the photosensitive layer of the obtained electrophotographic photosensitive member was analyzed, the tellurium concentration was 11.7% by weight on the substrate side,
It is 12.4% by weight on the free surface side and the arsenic concentration is 1.
9% by weight and 2.2% by weight on the free surface side.

Effect of the Invention Since the present invention performs vapor deposition using selenium alloy fine powder that has been subjected to surface oxidation treatment in advance as described above, means for suppressing the fractionation of additional elements as in the conventional method, for example, Fractionation of the additional element can be suppressed without using a shutter or the like. Therefore, according to the present invention, it is possible to produce an electrophotographic photosensitive member at low cost by using a simple apparatus.

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor comprising: a first step of oxidizing a surface of a selenium alloy fine powder; and a second step of depositing the oxidized selenium alloy fine powder on a conductive substrate. Manufacturing method. 2. The method according to claim 1, wherein the selenium alloy contains one or both of tellurium and arsenic.