JPS6223049A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to reduce fluctuation of characteristics during repeated uses by laminating an electrostatic charge generating layer so that a Vickers hardness, a surface roughness, and a glass transition point thereof may be in a specified range respectively. CONSTITUTION:The photosensitive body is obtained by successively laminating a charge transfer layer 2 made of an amorphous Se-Te alloy and the charge generating layer 4 made of an amorphous Se-Te-As alloy on a conductive substrate 1, resulting in forming an interlayer 3 made of a mixture of both layers between them. At that time, the layer 4 is formed so as to have a Vickers hardness of 50-60kg/mm<3> measured on the side of its surface, a surface roughness of 0.01-0.03mum in terms of an average center line roughness, and a glass transition point of 55-75 deg.C, thus permitting the obtained electrophotographic sensitive body to be high in sensitivity and small in fluctuation of the electrophotographic characteristics at the time of repeated uses.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a selenium-based functionally separated electrophotographic photoreceptor comprising a charge transport layer and a charge generation layer successively laminated on a conductive substrate.

[Prior art and its problems]

As an amorphous selenium-based photoconductive material used as an electrophotographic photoreceptor (hereinafter simply referred to as a photoreceptor), in addition to pure selenium and a selenium-tellurium alloy, a selenium-arsenic alloy is also used. A photoconductor having a photoconductor layer made of AallBθ3 is known as a photoconductor with excellent crystallization resistance and printing resistance. This method is accompanied by complications such as limitation and installation of a pre-discharge process, which hinders miniaturization of the photoreceptor, for example, reduction in the diameter of the cylinder of a cylindrical photoreceptor. Furthermore, arsenic, which is one of the elements used, is expensive, and the advantage of 82B6B in that it has a high glass transition point makes manufacturing equipment complicated and expensive, making it difficult to reduce costs.

Therefore, as seen in JP-A-55-134856, a charge transport layer made of Se or Be-Te alloy is placed on a conductive substrate, and a Se-Aθ alloy (As:3
The functionally separated photoreceptor is laminated with a charge generation layer consisting of 0 to 42% by weight), which reduces arsenic consumption and improves light fatigue resistance.
Attempts have been made to improve durability. However, in a photoreceptor with such a structure, there is a difference in thermal expansion coefficient between the electrolyte transport layer and the charge generation layer, so cracks often occur in the charge generation layer due to internal stress during lamination by vacuum evaporation. , these cracks also appear on copies, significantly impairing image quality and rendering the photoreceptor unusable for practical use.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an electrophotographic photoreceptor that has high photosensitivity, less variation in characteristics during repeated use, and excellent crystallization resistance and printing resistance.

[Key points of the invention]

An object of the present invention is to sequentially laminate a charge transport layer made of an amorphous selenium/tellurium alloy and a charge generation layer made of an amorphous selenium/tellurium/arsenic alloy on a conductive substrate; In a photoreceptor having an intermediate layer between the charge generating layer and the charge generating layer, the Vickers hardness measured from the surface side of the charge generating layer is 50 to 65 Kf/-, and the surface of the charge generating layer is Roughness is center line average roughness (Ra) of 0.01
~0.03μm, and the glass transition point of the charge generation layer is 5.
This is achieved by keeping the temperature between 5 and 75°C.

[Embodiments of the invention]

The present invention will be explained below with reference to Examples.

Examples 1 to 9 As a vapor deposition material for a charge transport layer, 900 g of a selenium-tellurium alloy consisting of 5.5% by weight tellurium and the balance selenium was used for 5 US
A quartz boat was filled with 60 g of a selenium-tellurium-arsenic alloy having the composition shown in Table 1 for each side as a vapor deposition material for the charge generation layer, and then placed in a vacuum evaporation tank. Set to . Next, set the surface temperature to about 65℃.
An aluminum cylinder with an outer diameter of 90 mm and a length of 320 mm was attached to the support shaft, which was controlled at 10 rpm, and the support shaft was rotated at 10 rpm. Close the deposition tank and evacuate it to a vacuum level of 5 x 1.
When the temperature reaches 0 Torr IIC, turn on the heater of the boat for charge transport layer deposition and raise the temperature of this boat to 3
The temperature is raised to 25° C. in about 25 minutes and maintained at this temperature to evaporate the selenium-tellurium alloy. The time when the entire 900g has finished evaporating is determined by the increase in boat temperature.
The time required to maintain the temperature at 325°C is 23 minutes.

Two minutes after evaporation is complete, turn off the boat heater.

Furthermore, when the holding time at 325° C. reached 14 minutes, the heater of the charge generation layer deposition boat was turned on.
The temperature of this boat was controlled as shown in Table 1 for each side, and after the holding time to evaporate 60% of the 1160 g charge, the boat heater was switched off and the vacuum was broken after a further 2 minutes. After 10 minutes, open the vacuum chamber and take out the photoreceptor. In this way, a charge transport layer 2 made of a selenium-tellurium alloy and a charge generation layer 4 made of a selenium-tellurium-arsenic alloy are formed on a conductive substrate 1 as shown in a conceptual cross-sectional view in FIG. Nine photoreceptors were manufactured, each having an intermediate layer 3 in which the materials of both layers were mixed between the two layers. The film thickness when only the charge transport layer was deposited using the method of this example was 56 to 57 μm.
m, and the film thickness when only the charge generation layer is deposited is about 6 μm, but as mentioned above, in the actual photoreceptor of this example, both layers partially overlap, and the thickness of only the charge generation layer is approximately 6 μm. The film thickness of 25 to 75 inches overlaps with the charge transport layer and forms an intermediate layer.

Table 1 Comparative Example 1 A photoreceptor was prepared in the same manner as in Example 1, except that a selenium-tellurium alloy containing 15% by weight of tellurium and the balance selenium, which did not contain arsenic, was used as the vapor deposition material for the charge generation layer.

Comparative Example 2 A photoreceptor was produced in the same manner as in Example 1, except that a selenium-tellurium alloy containing 20% by weight of tellurium and the remainder selenium, which did not contain arsenic, was used as the vapor deposition material for the charge generation layer.

Table 2 shows the film thickness and electrophotographic properties of the photosensitive layer of these 11 photoreceptors. Here, the charging potential is +6 in the dark. OK
is the surface potential charged by corona discharge of V,
The dark decay rate indicates the retention ratio of this charged potential after 1 second in a dark place, and the half-decay exposure type is exposed to a halogen lamp with a color temperature of 28 b OK at an illuminance of 3 lux.
This is the value required for the initial charging potential value of 100v to attenuate to 500v, and the residual potential is the value after exposure of 10 lux·sec.

It can be seen that all the photoreceptors in Examples and Comparative Examples in Table 2 had good initial electrophotographic characteristics.

Next, a repeated copying test was conducted on each of these photoreceptors in order to examine changes in the characteristics of the photoreceptors when copying was performed repeatedly.

In order to conduct a repeated copying test, we used a commercially available Carlson type dry plain paper copying machine with a copying speed of 30 sheets/min for A4 paper, removed the developing unit and cleaning blade, and placed a surface potential at the position of the developing unit. Total Norov? At the same time as installing it, I modified it so that the fuser heater power switch would not turn on.

Next, prepare an sample chart. An ensample chart is an A3 paper-sized manuscript that is sized 3 times in the length direction.
Divide into equal parts, and each part's optical I Brass degree is 1) 0 =
1.3, I)0 = 0.3, Do = 0.
07. A photoreceptor sample is installed in a copying machine, and the charged potential is first adjusted to 750 to t90VK with the document table cover open. Next, place the sample chart and adjust the potential of the portion Do = 0.3 to 250 to 290 V with the document table cover closed. After adjustment, continuous operation is performed 300 times, and changes in potential of these three parts are recorded. Perform this test for each photoreceptor, and
Part 'kb-' of 00th Do = 0.3.

In other words, the amount of change in the dark area potential (ΔV8) and the potential at the 300th Do = 0.07 portion, that is, the blank area potential (
Table 3 shows the results of measuring VW).

The negative sign of the amount of change (ΔVa) in the potential at section fff in Table 3 indicates that the potential at the 300th time is smaller than the potential at the first time.

All photoreceptors have values that can be used for practical purposes.

This dark area potential corresponds to the charging potential of the photoreceptor, and the above results show that even if the photoreceptor is used repeatedly, its charging performance hardly changes and does not deteriorate. In addition, the potential at the blank area ('Vw) increases slightly at first for all photoreceptors, but it becomes saturated after about 100 cycles, and after that, no increase is observed until 300 cycles, and there is no problem in practical use. This blank area potential corresponds to the residual potential of the photoreceptor, and indicates that no problematic increase in residual potential is observed even when the photoreceptor is used repeatedly.

Next, the Vickers hardness of 9 Hv was measured for the monitor pieces that were simultaneously deposited on an aluminum disk having a diameter of 30+ m during the deposition of these 11 photoreceptors, about one month after the deposition.

Using a measuring device (Model MVK-K manufactured by Akashi Seisakusho), measurements were taken at 5 points each under the conditions of a load of 10 g, an ambient temperature of 22°C, and 1°C.

The average values are shown in Table 4.

Similarly, the glass transition point Tg of the vapor-deposited material was measured, which was peeled off from a monitor piece on which only the charge generation layer was vapor-deposited using a shutter on an aluminum disk during photoreceptor vapor deposition. The measuring device was a standard scanning type differential thermal analyzer manufactured by Rigaku Denki ■, and the heating rate was 10° C./min. The measurement results are also shown in Table 4.

Further, the roughness of the surface of the vapor deposited layer of these 11 photoreceptors was measured. After about one month of vapor deposition, the photoconductor was processed using a Talcer 7 type surface roughness needle manufactured by Rank Taylor Bobson.
The centerline average roughness Ra according to B 0601 was measured at an ambient temperature of 22±2°C. The average value of each three-point measurement is also shown in Table 4.

Table 4 Next, an accelerated life test was conducted to examine crystallization resistance.

These 11 photoreceptors were installed in a commercially available Carlson type dry-type plain paper copying machine with a copying speed of 30 sheets/minute of A4 paper, and 1000 A3 paper-sized originals were printed.
After copying a sheet and applying a load of actual use to the photoreceptor, the temperature
The product was left in an atmosphere of 0°C and 1°C and a relative humidity of 8 to 20%, and the time it took for crystallization to begin to be observed was determined as the lifespan. The results are shown in Table 5.

Table 5 As is clear from Tables 4 and 5, Hv is 50
Kll/- or less, Tg is 55°C or less, and Ra
The life of the photoreceptor of the comparative example, which has a diameter of 0.01 μm or less, is less than 100 hours, but the life of the photoreceptor of this example is extremely long. Even in Example 5, where av l 'rg and RaO values are relatively small, the lifespan is approximately twice as long as that of the comparative example, and as these values increase, the lifespan of the photoreceptor increases significantly. . In other words, it can be seen that the crystallization resistance of the photoreceptor is significantly improved.

If the roughness of the surface layer of the photoreceptor becomes too large, defects will appear in the resulting copied image. The roughness of the surface layer is R
It is desirable that a is in the range of 0.01-0.03 μm. Also,
As the Vickers hardness Hv increases, the printing resistance improves, and as the glass transition point Tg increases, the crystallization resistance improves, but since the amount of arsenic added to the charge generation layer increases, its vapor deposition becomes difficult. Moreover, the cost of materials also increases. H"f is in the range of 50 to 65 odor/-, Tg is 55 to '75℃
If it is within this range, practically sufficient printing resistance and crystallization resistance can be obtained, which is preferable.

〔Effect of the invention〕

According to the present invention, a charge transport layer made of an amorphous selenium-tellurium alloy and a charge generation layer made of an amorphous selenium-tellurium-arsenic alloy are sequentially laminated on a conductive substrate, and the charge transport layer and the charge In a photoreceptor having an intermediate layer having a mixture of compositions of both layers between the charge generation layer and the charge generation layer, the Vickers hardness measured from the surface side of the charge generation layer is 50 to 65 o/-, and the surface roughness of the charge generation layer is The center line average roughness (Ra) is 0. O1~
The glass transition point of the charge generation layer is 55 to 0.03 μm.
The temperature shall be 75°C.

By using a photoreceptor that exhibits such characteristics, there is less variation in electrophotographic characteristics during repeated use due to light sensitivity, and excellent crystallization resistance and printing resistance.
A sensitive body for fc electrophotography is obtained.

[Brief explanation of drawings]

FIG. 1 is a conceptual sectional view showing an embodiment of a photoreceptor according to the present invention. l... 4' is a sexual substrate, 2... charge transport layer, 3...
Middle class, Figure 1

Claims (1)

[Claims] 1) A charge transport layer made of an amorphous selenium-tellurium alloy and a charge generation layer made of an amorphous selenium-tellurium-arsenic alloy are sequentially laminated on a conductive substrate, and the charge transport layer and the charge generation layer In the electrophotographic photoreceptor, the electrophotographic photoreceptor has an intermediate layer between which the compositions of both layers are mixed, and the Vickers hardness measured from the surface side of the charge generation layer is 50 to 65 kg/
mm^2, the surface roughness of the charge generation layer is 0.01 to 0.03 μm in center line average roughness (Ra), and the glass transition point of the charge generation layer is 55 to 75°C. An electrophotographic photoreceptor characterized by: