JPS62145251A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having a very small dark decay of the electrostatic potential by providing an intermediate layer between the electroconductive substrate and the photoconductive layer composed of a non- crystalline silicon, and by incorporating a dry cured material of a solution contg. an org. aluminum compd. to the intermediate layer. CONSTITUTION:The photoconductive layer is composed of an i-type semiconductor having the non-crystalline silicon contg. hydrogen atom, as a main component. and at least one kind of a carbon atom, a nitrogen atom or an oxygen atom. The intermediate layer is composed of the dry cured material of the solution contg. the org. aluminum compd. As the used org. aluminum compd, aluminum trisacetylacetonate, etc., is examplified. The dry curing temp. of said compd. is 100-400 deg.C. The thickness of the film of the surface layer is preferable to be <=1mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor using amorphous silicon in the photosensitive layer.

In the conventional electrophotographic method, an electrostatic latent image is formed by charging a photoreceptor and exposing it to light, and after developing this latent image with a developer called a toner,
This is a method of transferring and fixing a toner image onto transfer paper to obtain a copy. The photoreceptor used in this electrophotographic method basically has a photosensitive layer laminated on a conductive substrate. Conventionally, the materials constituting the photosensitive layer have been inorganic photosensitive materials such as selenium or selenium alloys, cadmium sulfide, and zinc oxide, or organic photosensitive materials such as polyvinylcarbazole, trinitrofluorenone, bisazo pigments, phthalocyanine, pyrazoline, and hydrazone. Photosensitive materials are known,
The photosensitive layer is used as a single layer or a fiff layer. However, these conventionally used photosensitive layers have problems that still need to be solved in terms of durability, heat resistance, photosensitivity, etc.

In recent years, photoreceptors using amorphous silicon as the photosensitive layer have been known, and various attempts have been made to improve them. This photoreceptor using amorphous silicon has an amorphous film of silicon formed on a conductive substrate using silane (SiH2) gas using a glow discharge decomposition method. Hydrogen atoms are incorporated to exhibit photoconductivity. This amorphous silicon photoreceptor has a photosensitive layer that has a high surface hardness, is resistant to scratches, is resistant to abrasion, has high heat resistance, and has excellent mechanical strength. Furthermore, amorphous silicon has a wide spectral sensitivity range and has excellent photosensitivity, such as high photosensitivity. However, on the other hand, photoreceptors using amorphous silicon have the disadvantage that dark decay is large and a sufficient charging potential cannot be obtained even when charged. That is, an amorphous silicon photoreceptor is charged, imagewise exposed to form an electrostatic latent image,
Then, during development, the surface charge on the photoreceptor is attenuated until the image exposure step or even the charge on the part that has not been exposed to light during the development step, and the charge potential required for development is reduced to 1! ') I can't do it. This attenuation of the charging potential is likely to change depending on the influence of environmental conditions, and in particular, the charging potential decreases significantly in a high temperature and high humidity environment.

Furthermore, when an amorphous silicon photoreceptor is used repeatedly, its charging potential gradually decreases. If a copy is made using a photoreceptor with such a large dark attenuation of the charged potential, the copy will have a low image density and poor r-resistance in intermediate tones.

OBJECTS OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that eliminates the above-mentioned drawbacks of photoreceptors using amorphous silicon.

Furthermore, the object of the present invention is to use amorphous silicon, and
An object of the present invention is to provide an electrophotographic photoreceptor in which the dark decay of the charged potential is extremely small.

Another object of the present invention is to provide an electrophotographic photoreceptor whose charging characteristics are not affected by changes in the cloud surroundings of the external environment.

Another object of the present invention is to provide an electrophotographic photoreceptor with excellent image quality even after repeated use.

Furthermore, another object of the present invention is to provide an electrophotographic photoreceptor that has excellent electrophotographic properties such as mechanical strength, durability, heat resistance, and photosensitivity.

Structure of the Invention As a result of extensive research, the present inventor discovered that a conductive substrate,
The above object is achieved by providing an intermediate layer between the photoconductive layer and the photoconductive layer made of amorphous silicon, and using a dried and cured product of a solution containing at least one organic aluminum compound as the intermediate layer. I found it. The photoconductive layer used is an i-type semiconductor mainly composed of amorphous silicon and further containing at least one of carbon atoms, nitrogen atoms, and oxygen atoms.

(According to the present invention, in the electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially laminated on a conductive substrate, the photoconductive layer is made of amorphous silicon containing hydrogen atoms. The intermediate layer is made of an i-type semiconductor mainly composed of an i-type semiconductor and further contains at least one type of carbon atom, nitrogen atom, or oxygen atom, and the intermediate layer is a dry hardening solution containing at least one type of organoaluminum compound. An electrophotographic photoreceptor is provided.

Examples of organoaluminum compounds used to form the intermediate layer of the electrophotographic photoreceptor of the present invention include aluminum trisacetylacetonate, aluminum methoxide, aluminum ethoxide, aluminum isopropoxide, aluminum-n-propoxide, and aluminum Examples thereof include mu5ec-butoxide, aluminum lobe toxide, and the like.

In order to obtain the electrophotographic photoreceptor of the present invention, a solution of one or more of the above organoaluminum compounds dissolved in a suitable solvent is coated. Further, at this time, a solution obtained by mixing these organoaluminum compounds with an organosilicon compound may be used. Compounds generally called silane coupling agents are suitable as the organosilicon compound, such as vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, T-glycidoxypropyltrimethoxy Silane, T-methacryloxypropyltrimethoxysilane, N-β(aminoethyl)T-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, T-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane,
Methyltrimethoxysilane, dimethyldimethoxylan,
Examples include trimethylmonomethoxysilane, diphenyldimethoxysilane, diphenyljethoxysilane, and monophenyltrimethoxysilane. When such silane coupling agents are mixed and used, it is preferable that the silane coupling agents account for 5 to 50% of the total solid weight.

Thus, a solution containing an organoaluminum compound and optionally an organosilicon compound is applied onto the photoconductive layer.
The photoreceptor for electrophotography of the present invention is prepared by coating by a method such as spray coating, dip coating, knife coating or roll coating, and then curing. The dry smoke curing temperature can be set at any temperature between 100 and 400°C. Although the thickness of the surface layer finally obtained can be set arbitrarily, it is preferably 0.1 to 10 μm, particularly 1 μm or less.

The photoconductive layer mainly composed of amorphous silicon is S i If
Using one type of hydrogen silicon gas such as S, 5iaH6, 5i3He, S14H1O1, or a mixture thereof as a raw material, it is formed on a substrate by a method such as a glow discharge method, a sputtering method, an ion blasting method, or a vacuum evaporation method. Among them, plasma CVD (Chemical Va
A method (glow discharge method) in which silane (SiH2) gas or the like is decomposed by glow discharge using a por deposition method is preferable from the viewpoint of controlling the hydrogen content in the film. Further, in this case, in order to more efficiently contain hydrogen, hydrogen (H2) gas may be separately introduced into the plasma CVD apparatus at the same time as silane gas or the like.

In addition, in this photoconductive layer mainly composed of amorphous silicon,
A trace amount of boron (B) is added to make the layer more of an l-type semiconductor.
) can be added. For this addition of boron atoms, boron (B2H,) gas is usually used as a raw material.

In this case, the amount of boron atoms added is about 10 to 1100 pp.

Further, in the electrophotographic photoreceptor according to the present invention, the photoconductive layer is made of an i-type semiconductor mainly composed of amorphous silicon containing hydrogen atoms, and further includes at least one of carbon atoms, nitrogen atoms, and oxygen atoms. Contains one type. The inclusion of such atoms is particularly preferable from the viewpoint of increasing the dark resistance of the photosensitive layer, increasing the photosensitivity, and further increasing the charging ability (charging potential per unit film thickness).

Furthermore, it is also possible to add an element such as germanium (Ge) to the photoconductive layer film for the purpose of increasing the sensitivity of the photoreceptor in the long wavelength range. Further, by adding halogen atoms, it is also possible to increase the dark resistance.

Thus, in order to prepare the photoconductive layer of the electrophotographic photoreceptor of the present invention, silicon hydride gas, which is the main raw material, and hydrogen gas, if desired, are used in a plasma CVD apparatus, and together with these gases, Glow discharge decomposition may be performed by introducing a gaseous compound containing the necessary elements. As mentioned above, effective discharge conditions for forming a photoconductive layer made of amorphous silicon by the plasma CVD method include, for example, in the case of AC discharge, the frequency is usually 0.1 to 30 MHz, and the degree of vacuum during discharge is 0.1-5 Tarr, substrate heating temperature 100-40
It is 0°C. Therefore, the thickness of the photoconductive layer mainly composed of amorphous silicon is preferably 1 to 100 μm, particularly 10 to 50 μm.

As the conductive substrate, a metal such as aluminum, nickel, chromium, stainless steel, or brass, a plastic sheet or glass having a conductive film, or paper treated to be conductive can be used. Moreover, the shape of the conductive substrate can be any shape such as a cylindrical shape, a flat plate shape, an endless belt shape, or the like.

101 Next, the electrophotographic photoreceptor of the present invention will be further explained with reference to comparative examples and examples of the present invention.

Comparative Example 1: A cylindrical Al substrate was installed at a predetermined position in the reaction chamber of a capacitively coupled plasma CVD apparatus, the substrate temperature was maintained at a predetermined temperature of 250°C, and 100% silane (Si) was placed in the reaction chamber.
H4) 120cc of gas per minute.

100 ppm diborane (B2H6) gas diluted with hydrogen was introduced at 20 cc per minute, 100% ethylene (C, H,) gas was introduced at 12 (:C) per minute, and 100% hydrogen (N2) gas was introduced at a rate of 880 C/min. Inside the reaction tank Q, 5 Torr
After maintaining the internal pressure at , 13.56 MHz high frequency power was applied to generate glow discharge, and the output of the high frequency power source was maintained at 85 W. In this way, the cylindrical A
A photoreceptor having a photoconductive layer having a thickness of 25 μm and consisting of a type 1 semiconductor mainly composed of amorphous silicon and containing carbon atoms as an impurity on a substrate was used.

When the photoreceptor obtained in this way was placed in a copying machine and the image quality was evaluated using a positive corona charging method, an image density that was acceptable for practical use was initially obtained, but as copying operations were repeated, it gradually deteriorated. The image density decreased.

Example 1: A solution consisting of 1 part by weight of aluminum trisacetylacetonate and 30 parts by weight of isopropyl alcohol was dip-coated onto the same cylindrical A plate as in Comparative Example 1, and heated at 250°C.
The mixture was dried and cured in an oven for 2 hours to provide an intermediate layer having a thickness of 0.1 μm. Next, on this intermediate layer, by the same method as in Comparative Example 1, a photoconductive layer mainly composed of amorphous silicon having the same content as in Comparative Example 1 was provided with approximately the same thickness as in Comparative Example 1. When the photoreceptor thus obtained was placed in a copying machine and the image quality was evaluated using a positive corona charging method, an image density that was acceptable for practical use was obtained at the initial stage. Further, although the copying operation was repeated 50,000 times, no decrease in image density was observed. At the same time, copying tests conducted using the negative corona charging method also gave good results, similar to those using the positive charging method.

Comparative Example 2: A cylindrical AI substrate was installed at a predetermined position in the reaction chamber of a capacitively coupled plasma CVD apparatus, the substrate temperature was maintained at a predetermined temperature of 250°C, and 100% silane (Si) was placed in the reaction chamber.
H<) gas at 120cc per minute.

Hydrogen diluted 100ppm diborane (B2H,) gas at 20CG/min, 100% Nitrogen (N2) gas at 85c/min
c. Furthermore, 100% hydrogen (N2) gas was introduced at a rate of 15 cc per minute to maintain an internal pressure of 5 Torr inside the reaction tank, and then 13.56 MHz high-frequency power was applied to generate a glow discharge. The output of the high frequency power supply is 85
I kept it at W. In this way, a photoreceptor was obtained having a photoconductive layer having a thickness of 25 μm and consisting of an l-type semiconductor mainly composed of amorphous silicon and containing nitrogen atoms as impurities on a cylindrical A1 substrate. The photoreceptor thus obtained was placed in a copying machine and the image quality was evaluated using a positive corona charging method.
At the initial stage, a practically acceptable image density was obtained, but as copying operations were repeated, the image density gradually decreased.

Example 2: Same cylindrical shape A as Comparative Example 2! Aluminum-5 on the board
A solution consisting of one stirred part of ec-butoxide and 40 parts by weight of ethyl alcohol was applied by dip coating and dried and cured in an oven at 250°C for 2 hours to form an intermediate layer with a thickness of 0.2 μm. next,
Comparative Example 2 was applied onto this intermediate layer by the same method as Comparative Example 2.
A photoconductive layer mainly composed of amorphous silicon having the same content as that of Comparative Example 2 was provided with approximately the same thickness as Comparative Example 2. When the photoreceptor thus obtained was placed in a copying machine and the image quality was evaluated using a positive corona charging method, an image density that was acceptable for practical use was obtained at the initial stage. Further, although the copying operation was repeated 50,000 times, no decrease in image density was observed. At the same time, copying tests conducted using the negative corona charging method also gave good results, similar to those using the positive charging method.

Comparative Example 3: A cylindrical A1 substrate iδ was set at a predetermined position in the reaction chamber of a capacitively coupled plasma CVD apparatus, the substrate temperature was maintained at a predetermined temperature of 250°C, and 100% silane (S) was placed in the reaction chamber.
iH,) 120cc of gas per minute.

Hydrogen diluted 100ppm diborane (B2) gas at 20cc/min and 1100% acidic (02) gas at 1.0cc/min.
0cc, and 100% hydrogen (H2) gas at 99c/min
After maintaining the internal pressure in the reaction tank at 0.5 Torr, a high frequency power of 13.56 MHz was applied to generate a glow discharge, and the output of the high frequency power source was maintained at 85 W. In this way, a photoreceptor was obtained having a photoconductive layer having a thickness of 25 μm and consisting of an l-type semiconductor mainly composed of amorphous silicon and containing carbon atoms as impurities on a cylindrical An substrate. When the photoreceptor obtained in this way was placed in a copying machine and the image quality was evaluated using a positive corona charging method, an image density that was acceptable for practical use was initially obtained, but as copying operations were repeated, it gradually deteriorated. The image density decreased.

Example 3: Aluminum-5 was added to the same cylindrical Aβ substrate as in Comparative Example 3.
Immerse yourself in a solution consisting of 1 part by weight of ec-butoxide, 1 part by weight of methyltrimethoxysilane, 30 parts by weight of isopropyl alcohol, and 30 parts by weight of ethyl alcohol. Takashi applied,
Dry smoke curing was performed in an oven at 250° C. for 2 hours to provide a 0.2 μm thick intermediate layer. Next, on this intermediate layer, by the same method as in Comparative Example 3, a photoconductive layer mainly composed of amorphous silicon having the same contents as in Comparative Example 3 was provided with approximately the same thickness as in Comparative Example 3. When the photoreceptor thus obtained was placed in a copying machine and the image quality was evaluated using a positive corona charging method, an image density that was acceptable for practical use was obtained at the initial stage. Further, although the copying operation was repeated 50,000 times, no decrease in image density was observed. At the same time, copying tests conducted using the negative corona charging method also gave good results, similar to those using the positive charging method.

Effects of the Invention The electrophotographic photoreceptor of the present invention maintains the excellent properties of a photoreceptor made of amorphous silicon, such as high mechanical strength, high durability, high heat resistance, and high photosensitivity, and also has an external Rm. It has a high charge retention ability without being affected by the environment or the number of times of use, and can provide images of excellent quality.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising an intermediate layer and a photoconductive layer sequentially laminated on a conductive substrate, wherein the photoconductive layer is mainly made of amorphous silicon containing hydrogen atoms. type semiconductor, and further contains at least one type of carbon atom, nitrogen atom, or oxygen atom, and the intermediate layer contains at least one organic aluminum compound.
1. A photoreceptor for electrophotography, characterized in that it is made of a dried and cured product of a solution containing various types of photoreceptors.