JPS61132956A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To reduce the deterioration of the dark attenuation characteristics of an electrophotographic sensitive body and to lower a residual potential by adding Cl to a high-purity Se-Te alloy in a trace amt. of <=10ppm. CONSTITUTION:The Se-Te alloy having the purity of >=99.999% can be reduced in the residual potential by adding Cl by a trace amt. of <=10ppm and the use of a very small amt. of Cl reduces the deterioration of the dark attenuation characteristics. Such addition of Cl to the alloy can be executed by adding a prescribe amt. of Cl in the form of SeCl4 or the like at the time of melting the mixture of Se and Te in a prescribed compsn., or bubbling Cl2. The intended electrophotographic sensitive body is obtained by using the Se-Te alloy thus obtained as an electrophotographic sensitive material, that is, an evaporation source, and depositing it on a conductive substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a superalloy for electrophotographic photoreceptors and a vapor-deposited film for electrophotographic photoreceptors produced by vacuum-depositing the alloy, and particularly to a high-purity film for electrophotographic photoreceptors. It is characterized in that a very small amount of chlorine, less than I G ppm, is added to the selenium-tellurium alloy. The electrophotographic photoreceptor according to the present invention has succeeded in reducing the residual potential by minimizing the deterioration of the dark decay characteristic.

Electrophotography is a photographic method that utilizes the photoconductivity of substances and electrostatic phenomena, and several methods have been established. The method of obtaining electrophotographs is called the Xerox method. As is well known, the Xerox method consists of the following steps: (a) Band 1! : Charge the surface of a photoreceptor in which an amorphous polyurethane or selenium alloy with high dark resistance is deposited on a metal substrate.

(b) Exposure (printing): When exposed to a light image, the electrical resistance of the selenium or selenium alloy in the irradiated area decreases,
Charges on the surface escape to the metal substrate, and the residual charge density on the photosensitive plate varies depending on the amount of exposure, resulting in a t# latent image having the same shape as the original image on the photosensitive plate surface.

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

(d3 Transfer: Place a suitable piece of paper on the surface of the photosensitive plate after development and cause corona discharge to occur from the stomach surface. The toner on the photosensitive plate will be attracted to the paper, and the toner powder image will be transferred to the paper. .

(@) Fixing: Once the transfer is complete, remove the paper and heat it with an infrared heater to fuse the toner skin oil to the paper.

By carrying out the above process, a copied image (electrophotography) of the original image can be obtained, but the characteristics such as sharpness and reproducibility of the copied image largely depend on the performance of the photoreceptor selenium or selenium alloy. Although several selenium alloys have been considered, selenium-tellurium alloys are widely used for the purpose of providing long-wavelength sensitivity and increasing the number of printing sheets by increasing hardness.

In order to judge the performance of the photoreceptor, (a) the corona charging characteristic, f
(Exposure) Dark attenuation characteristic related to the charge lost while holding the photoreceptor charged by corona discharge, (/→ Charge voltage exposure attenuation characteristic that represents the relationship in which the amount of charge held in the dark disappears due to exposure to light. , 2) Residual potential, which represents the potential that remains without disappearing until the electricity is restored after exposing the photoreceptor, is taken into consideration.

Residual potential in particular plays an important role in stabilizing the contrast and image quality of electrophotography and the characteristics of selenium photoreceptors. However, the selenium-tellurium alloy photoreceptor has a serious drawback of having a large residual potential, and for this reason, chlorine is added (for example, in Japanese Patent Application Laid-Open No. 55-1594).
No. 45). In the actual experiments and test examples reported so far, a large amount of chlorine of 30 to 500 ppm has been added, and even if the residual potential can be reduced by adding such a large amount of chlorine, A problem arises in (b) that the dark decay characteristic deteriorates.

In this way, chlorine has been conventionally added to selenium-tellurium alloys to reduce the residual potential, but the residual potential cannot be reduced unless the amount of chlorine added is considerably large. The addition of chlorine causes a sudden deterioration of dark decay characteristics, resulting in an overall superior selenium
A tellurium alloy-based electrophotographic photoreceptor has not yet been obtained.

OBJECTS OF THE INVENTION An object of the present invention is to reduce the deterioration of dark decay characteristics and reduce the residual potential in a selenium-tellurium alloy electrophotographic photoreceptor.

Summary of the Invention The present inventors have discovered that the selenium conventionally used to prepare selenium-tellurium alloys has a purity of 4 to 5N;
It was noted that Ryuho Tail also has a purity of 4N at best and contains many impurities. Although it is speculation,
It is thought that when raw materials of such purity are used, these impurities act as traps for electrons and holes, increasing the residual potential, and therefore increasing the amount of chlorine required to compensate for these traps. . Therefore, we thought that if we prepare an alloy using selenium and tellurium of higher purity than conventional raw materials, there would be fewer impurities that act as traps, so we could reduce the amount of chlorine required to compensate for the traps, and we conducted repeated studies.

As a result, it has been found that in a selenium-tellurium alloy having a purity exceeding 99.999%, the residual potential can be lowered by adding a trace amount of chlorine of 10 ppm or less. Since the amount of chlorine added is small, the deterioration of dark decay characteristics is small. Prior to the present invention, no experiments had actually been conducted on the addition of chlorine in extremely small amounts of IQ ppm or less, and the behavior of such extremely small amounts of chlorine was completely unknown. It was completely unexpected that it was possible to reduce the

Thus, the present invention provides: 1) an electrophotographic photosensitive material characterized in that 10 ppm or less of chlorine is added to a selenium-tellurium alloy having a purity of over 99.999%; 2) a photosensitive material for electrophotography having a purity of over 99.999%. 99.999' %
Adding 10% chlorine to the selenium-tellurium alloy that fosters purity that makes you feel
An electrophotographic photoreceptor comprising one or more thin film photosensitive layers formed on a conductive substrate using a thin film forming material added in an amount of ppm or less.

Provide photography.

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a high purity selenium-tellurium alloy with a purity greater than 99.999% is used. At present, purity 6
Techniques for producing high-purity selenium with a purity of 6N and high-purity tellurium with a purity of 6N have been established, and using these techniques, the above-mentioned high-purity selenium-tellurium alloy can be easily produced manually. The amount of tellurium is generally set at 5 to 3-0% by weight; if it is less than 5%, the desired objectives of increasing long-wavelength sensitivity and printing durability cannot be achieved, while if it exceeds 30%, the selenium sensitivity characteristics may exceed the allowable level. worsens.

The addition of chlorine to the alloy can be brought about by adding a specified amount of selenium in the form of selenium chloride or the like during mixing and melting of selenium and tellurium in a predetermined proportion, or by injecting chlorine by bubbling. In order to facilitate the addition of trace amounts, a certain amount of high purity selenium containing a high level of chlorine, such as 1000 ppm, is prepared and selenium chloride is added.
An appropriate amount may be added to obtain the target amount of chlorine when melting the WIV alloy.1゜The electrophotographic photosensitive material thus obtained, that is, the selenium-tellurium alloy as a deposition source, is deposited on the substrate by vacuum deposition. An electrophotographic photoreceptor is obtained. The conditions for vacuum deposition are not particularly limited, and commonly used conditions are sufficient. Evaporation source temperature is 250-35
0°C1 substrate, temperature is 55-75°C, vacuum degree is 10-a
〜IQ−'' Torrs vapor deposition time is 60 to 150 minutes, and suitable conditions are appropriately selected and carried out.The substrate supporting the vapor deposited film may be a metal such as aluminum or steel, or a metallized glass or metal. Materials such as spotted snacks are used.

The vapor deposited film can also be formed by placing selenium and chill y into separate evaporation sources and performing simultaneous vapor deposition.

In that case, a predetermined amount of chlorine is contained in selenium, for example.

The preferred amount of chlorine added in the present invention is 2 to 5 pprn.
It is.

Regarding photoconductors for copying machines, a photoconductor employing a multilayer structure called a functionally separated type has also been proposed.

For example, in the case of a two-layer structure, the surface layer that receives direct light irradiation and contacts the paper surface is made of 5e, which has excellent long-wavelength sensitivity and abrasion resistance.
-Te-based material is used, and pure selenium is used for the substrate side layer. The present invention can be applied as one or more photosensitive layers of such a laminated electrophotographic photoreceptor.

Example High purity selenium (purity 6N) and high purity tellurium (purity 6N)
Selenium and selenium to which 1000 ppm of chlorine had been added were vacuum sealed in a Vilex ampoule, which was reacted in a rocking furnace at 550° C. for 2 hours, and then taken out of the furnace and cooled in the air.

The ampoule was then crushed to remove the alloy. The tellurium concentration is 12 ft%, the amount of chlorine added is 2.5.7.10,
An alloy was prepared so as to have a concentration of 20 ppm.

The alloy produced in this way is ssmx by resistance heating.
Vacuum deposition was carried out on an ss- mirror finished aluminum substrate. The deposition conditions are as follows.

Evaporation source temperature: 500°C Substrate temperature: 70''C Vacuum degree: 2 x 10-' Torr Vapor deposition time: The thickness of the deposited film formed on the aluminum substrate for 90 minutes or more was approximately 50 μm.

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

Corona discharge voltage 5KV Dark decay time 10 seconds Light irradiation time 30 seconds Light illuminance 10 lux Static elimination illuminance, time 20000 Lx, number of repetitions for 2 seconds
The drawing shows the relationship between the results of 30 or more measurements and the amount of chlorine added to the alloy.

In FIG. 1, the curve ▪ indicates the initial surface potential (vo), and the curve ▪ indicates the surface potential in the dark state (vl.) 10 seconds after charging. As can be seen from the graph, when the amount of chlorine added exceeds 10 ppm, the initial surface potential (v
o) decreases below the allowable level, and (V + o) also decreases significantly, deteriorating the dark decay characteristics.

FIG. 2 shows the residual potential (V r ). The residual potential is 2
It can be seen that the addition of ppm or more of chlorine results in a sufficient reduction.

Effects of the Invention The present invention improves the residual potential characteristics of selenium-tellurium alloys, which conventionally required the addition of So-SOO ppm of chlorine, with less than 10 ppm, and the deterioration of dark decay characteristics due to the addition of chlorine can be reduced. .

Figure 1 is a graph showing the relationship between the amount of chlorine added and the initial surface potential (vo) and the surface potential 10 seconds after charging (vl6), and Figure 2 is a graph showing the relationship between the amount of chlorine added and the residual potential (V r
) is a graph showing the relationship between

Claims (1)

[Scope of Claims] 1) A photosensitive material for electrophotography, characterized in that 10 ppm or less of chlorine is added to a selenium-tellurium alloy having a purity exceeding 99.999%. 2) An electrophotographic photoreceptor comprising a thin film photosensitive layer formed on a conductive substrate using a thin film forming material in which 10 ppm or less of chlorine is added to a selenium-tellurium alloy having a purity exceeding 99.999%. 3) Adding 10pp of chlorine to a selenium-tellurium alloy with a purity of over 99.999% in a laminated electrophotographic photoreceptor
An electrophotographic photoreceptor comprising one or more thin film photosensitive layers formed on a conductive substrate using a thin film forming material added with an amount of m or less.