JPH0239787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a selenium-arsenic-oxygen-based electrophotographic photosensitive material and an electrophotographic photoreceptor comprising a photosensitive layer prepared by vacuum-depositing the material. By using oxygen instead of chlorine, which is problematic in handling in the selenium-arsenic-chlorine system proposed in the past, we have succeeded in reducing the residual potential while maintaining good dark decay characteristics.
The present invention can be applied not only to the photosensitive layer of a single-layer electrophotographic photoreceptor, but also to the photosensitive layer of a laminated electrophotographic photoreceptor.

Background of the Invention Electrophotography is a photographic method that utilizes the photoconductivity of substances and electrostatic phenomena, and several methods have been established. The method of obtaining electrophotography by transfer is called the Xerox method. As is well known, the Xerox method consists of the following steps: (a) Charging: The surface of a photoreceptor, in which amorphous selenium or selenium alloy with high dark resistance is deposited on a metal substrate, is charged.

(b) Exposure (printing): When exposed to a light image, the electrical resistance of the selenium or selenium alloy in the irradiated area decreases, the surface charge escapes to the metal substrate, and the remaining charge density on the photosensitive plate decreases due to exposure. A difference occurs depending on the amount, and an electrostatic latent image with the same shape as the original image is formed on the surface of the photosensitive plate.

(c) Development: By sprinkling the surface of the photosensitive plate with a mixed powder of toner made of fine carbon powder coated with resin and carrier consisting of glass beads, the toner adheres to the latent image area, and the latent image becomes a visible image. Become.

(d) Transfer: When a suitable paper is placed on the surface of the photosensitive plate after development and a corona discharge is applied from the back side, the toner on the photosensitive plate is attracted to the paper and the toner powder image is transferred to the paper. .

(e) Fixing: Peel off the paper with the transfer and heat it with an infrared heater to fuse the toner resin to the paper.

A photoreceptor for a copying machine is usually manufactured by vacuum-depositing selenium or a selenium alloy on the surface of a drum made of aluminum or the like. Furthermore, a photoreceptor employing a multilayer structure called a functionally separated type has also been proposed. For example, in the case of a two-layer structure, the first layer (surface layer) that is directly exposed to light and in contact with the paper surface is made of a Se-Te alloy with excellent long-wavelength sensitivity and wear resistance.
As-based alloy is used and the second layer (substrate side layer)
Pure selenium is used for The first layer is CGL
(Charge Generation Layer) and the second layer is called CTL (Charge Transfer Layer).

The sharpness, reproducibility, and other characteristics of the copied image greatly depend on the performance of the deposited film itself in the case of a single-layer structure, or the performance of the above-mentioned CTL (collectively referred to as the photosensitive layer) in the case of a multi-layer structure. Depends on it.

In order to judge the performance of the photosensitive layer, (a) corona discharge characteristics representing the amount of charge given by corona discharge with a constant output, and (b) the amount of charge lost while holding the photoreceptor charged by corona discharge. Related dark decay characteristics, (c) charge voltage exposure decay characteristics that indicate the speed at which the amount of charge held in the dark disappears due to exposure, and (d) potential that remains without disappearing to zero after exposing the photoreceptor to light. Residual potential, etc. representing , are considered.

In order to stabilize the contrast and image quality of electrophotography as well as the characteristics of the photosensitive layer, it is particularly required that the dark decay is low and the residual potential is low. Pure selenium has a relatively high residual potential, so
Additions of chlorine have been used to reduce the residual potential of selenium. Although the residual potential was reduced by adding a trace amount of chlorine of 10 ppm or less, it had the disadvantage of deteriorating the dark decay characteristics. Furthermore, it was difficult to add a trace amount of chlorine of 10 ppm or less, and there were also problems in productivity.

In order to improve these drawbacks, arsenic and chlorine are simultaneously added to selenium.
For example, JP-A-58-11950 contains 5 to 300 ppm of chlorine and 0.01 to 0.5% by weight of arsenic to selenium, and the content ratio of chlorine and arsenic is 250 to 300 ppm.
Discloses a photoreceptor that is 1200 ppm/wt%.

Thus, selenium-arsenic-chlorine materials exhibit relatively excellent performance, but chlorine is usually added in the form of selenium tetrachloride, and there are many problems in handling, such as strong deliquescent properties and easy vaporization.

Therefore, it would be extremely beneficial from a production technology perspective if an alternative element could be found that is less problematic than the addition of chlorine, can be easily added, and yet provides at least comparable electrophotographic properties.

SUMMARY OF THE INVENTION With this in mind, a number of elements were tested and it was found that oxygen could serve as a substitute.

Therefore, the present invention provides 1 selenium with 10 to 10000 ppm arsenic and 1 to 10000 ppm arsenic.
A photosensitive material for electrophotography characterized by adding 1000 ppm oxygen, 2. 10 to 10000 ppm arsenic to selenium, and 1.
3. An electrophotographic photoreceptor comprising a thin film photosensitive layer formed on a conductive substrate using a thin film forming material containing 1000 ppm oxygen, and 3. In a laminated electrophotographic photoreceptor, 10% of selenium is added.
Provided is an electrophotographic photoreceptor having one or more thin film photosensitive layers formed on a conductive substrate using a thin film forming material to which ~10,000 ppm arsenic and 1~1,000 ppm oxygen are added.

Specific description of the invention The selenium used in the present invention is 4N
Although it seems possible to use a conventional grade of ~5N, recently a higher purity product (6N) has also been manufactured, and such a high purity (6N) product is also used in the present invention. It is preferable.
High-purity selenium has fewer impurity traps and a lower residual potential. For example, conventional selenium exhibits a residual potential of 47V, while high-purity selenium with 6N purity has a residual potential of 28V.

In the present invention, 1 to 1000 ppm oxygen is added for the purpose of reducing residual potential. The amount of oxygen added depends on the purity of the selenium, but is chosen to give a residual potential of approximately 10V. Even if oxygen is added in excess of 1000 ppm, the effect is substantially saturated. Also, oxygen
When added in excess of 1000 ppm, bumping tends to occur during vapor deposition, causing defects in the vapor deposited film. Arsenic is added depending on the amount of oxygen mainly to prevent deterioration of dark decay characteristics, and is
It can be added in a range of 10000ppm. Oxygen and arsenic in the above range cooperate to reduce the residual potential while maintaining good dark decay characteristics. The preferred range is arsenic 100-10000ppm and oxygen 10-1000ppm.
It is 1000ppm.

Oxygen is added in the form of a master alloy made from SeO ₂ or Se-SeO ₂ or by oxygen bubbling;
This poses no problem in handling compared to the case of adding chlorine. Arsenic is added in the form of pure arsenic, Se-As alloy, or As ₂ Se ₃ .

An electrophotographic photoreceptor is obtained by vacuum-depositing the selenium-arsenic-oxygen photosensitive material as a vapor-deposited film on a drum conductive substrate.
As mentioned above, single-layer type and laminated type photoreceptors have been put into practical use. In the latter case, the photosensitive material of the present invention is used to form a photosensitive layer.

The conditions for vacuum evaporation are not particularly limited;
The conditions normally practiced are sufficient. Evaporation source temperature 250 to 350℃, substrate temperature 55 to 75℃, degree of vacuum 10 ^-5 to
The deposition can be carried out by selecting appropriate conditions within the range of 10 ⁻⁶ Torr and deposition time of 60 to 130 minutes. As the substrate, a metal such as aluminum or steel, metalized paper, or plastic is used.

Effects of the Invention By simultaneously adding arsenic and oxygen to selenium, an effect at least comparable to the simultaneous addition of arsenic and oxygen can be obtained. Addition of oxygen is easier to handle than addition of chlorine, and has great advantages in terms of production technology.

Example: To produce Se-As-O alloy, Nippon Mining Co., Ltd.
Predetermined amounts of manufactured high-purity selenium (6N), arsenic (6N), and selenium dioxide (4N) were each weighed out and vacuum-sealed into a Pyrex ampoule with an outer diameter of 30 mm and a length of 220 mm. This was melted at 550° C. for 2 hours while rocking at a rate of 10 times/minute in a rocking heating furnace.
Thereafter, the ampoule was crushed to remove the alloy.

The alloy produced in this way is heated by resistance heating.
Vacuum deposition was performed on a 55 mm x 55 mm mirror-finished aluminum substrate. The deposition conditions are as follows.

Evaporation source temperature: 300°C Substrate temperature: 70°C Vacuum degree: 2×10 ^-6 Torr Vapor deposition time: 90 minutes The thickness of the deposited film formed on the aluminum substrate under the above conditions was approximately 50 μm.

The electrophotographic properties of the alloy vapor-deposited film thus obtained were measured using an electrostatic testing device. The measurement conditions are as follows.

Corona discharge voltage 5kV Light irradiation time 2 seconds Light illuminance 3000 lux Number of repetitions 200 As constant at 2000ppm, oxygen from 1ppm
The results of adding up to 1000 ppm are shown in the drawing. In FIG. 1, the curve shows the initial surface potential V ₀ and the curve is the potential V ₁₀ after 10 seconds of dark state retention.
Figure 2 shows the residual potential. From the drawings, it can be seen that the residual potential can be reduced without deteriorating the dark decay characteristics.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the amount of oxygen added and the surface potential with a constant arsenic concentration of 2000ppm, and the second
The figure is also a graph showing the relationship between the amount of oxygen added and the residual potential.

Claims (1)

[Claims] 1 Selenium with 10 to 10,000 ppm arsenic and 1 to
A photosensitive material for electrophotography characterized by the addition of 1000 ppm oxygen. 2 Selenium with 10~10000ppm arsenic and 1~
An electrophotographic photoreceptor comprising a thin film photosensitive layer formed on a conductive substrate using a thin film forming material added with 1000 ppm oxygen. 3 In the laminated electrophotographic photoreceptor, selenium contains 10
An electrophotographic photoreceptor comprising one or more thin film photosensitive layers formed on a conductive substrate using a thin film forming material containing ~10,000 ppm arsenic and 1~1,000 ppm oxygen above or below a pure selenium or other photosensitive layer.