JPH0727255B2 - Electrophotographic photoconductor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photoconductor, and more particularly to an electrophotographic photoconductor using amorphous silicon in a photosensitive layer.

2. Description of the Related Art The electrophotographic method is a method for obtaining a copy by forming an electrostatic latent image on a photoconductor by charging and imagewise exposing it, developing the latent image with a developer, and then transferring and fixing the toner image on a transfer paper. Are known. The photoconductor used in this electrophotographic method has a basic structure in which a photosensitive layer is laminated on a conductive substrate. Then,
Conventionally, as the material constituting the photosensitive layer, an inorganic photosensitive material such as selenium or selenium alloy, cadmium sulfide, zinc oxide, or an organic photosensitive material such as polyvinylcarbazole, trinitrofluorenone, bisazo pigment, phthalocyanine, pyrazoline, or hydrazone. It is known and is used as a single layer or a laminate of photosensitive layers. However, these conventionally used photosensitive layers still have problems to be solved in terms of durability, heat resistance and photosensitivity.

In recent years, photoreceptors using amorphous silicon as the photosensitive layer have been known, and various improvements have been attempted. A photoreceptor using this amorphous silicon is one in which an amorphous film of silicon is formed on a conductive substrate by glow discharge decomposition method of silane (SiH ₄ ) gas. It has photoconductivity due to the incorporation of hydrogen atoms into it. This amorphous silicon photoreceptor has a high surface hardness of the photosensitive layer, is hard to be scratched, is resistant to abrasion, and has high heat resistance.
It also has excellent mechanical strength. Further, amorphous silicon has a wide spectral sensitivity range and has excellent photosensitivity so as to have high photosensitivity. On the other hand, however, the photoconductor using amorphous silicon has a drawback that dark decay is large and a sufficient charging potential cannot be obtained even when charged. That is, when the amorphous silicon photoconductor is charged, imagewise exposed to form an electrostatic latent image, and then developed, the surface charge on the photoconductor remains until the image exposure step.
Alternatively, even the electric charge of the portion which was not irradiated with light during the developing step is attenuated, and the charging potential required for the developing cannot be obtained. The decay of the charging potential is likely to change due to the influence of environmental conditions, and particularly in a high temperature and high humidity environment, the charging potential is drastically reduced. Furthermore, the charge potential of an amorphous silicon photoreceptor gradually decreases when it is repeatedly used. When a copy is made using such a photoreceptor having a large dark decay of the charging potential, the copy has low image density and poor halftone reproducibility.

OBJECT OF THE INVENTION It is an object of the present invention to provide an electrophotographic photosensitive member which solves the above-mentioned drawbacks of the photosensitive member using amorphous silicon.

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

Another object of the present invention is to provide an electrophotographic photosensitive member whose charging characteristics are not affected by changes in the atmosphere of the external environment.

Another object of the present invention is to provide an electrophotographic photoreceptor having excellent image quality even if it is repeatedly used.

Still another object of the present invention is to provide an electrophotographic photoreceptor having excellent electrophotographic characteristics such as mechanical strength, durability, heat resistance and photosensitivity.

As a result of earnest research, the present inventor has coated a photoconductive layer made of amorphous silicon on a conductive substrate, and further laminated a surface layer on the photoconductive layer. It has been found that the above object can be achieved by using a dry-cured product of a solution containing at least one aluminum acetylacetonate complex or aluminum alkoxide. A semiconductor mainly containing amorphous silicon is used as the photoconductive layer.

Thus, according to the present invention, in the electrophotographic photosensitive member formed by sequentially stacking the photoconductive layer and the surface layer on the conductive substrate, the photoconductive layer is mainly composed of amorphous silicon containing hydrogen atoms. An electrophotographic photoreceptor is provided which is made of a semiconductor, and the surface layer is a dried and cured product of a solution containing at least one aluminum acetylacetonate complex or aluminum alkoxide.

Preferred examples of the aluminum acetylacetonate complex or the aluminum alkoxide used for forming the surface layer of the electrophotographic photoreceptor of the present invention include aluminum trisacetylacetonate, aluminum methoxide, aluminum ethoxide, and aluminum isolate. Examples include propoxide, aluminum-n-propoxide, aluminum-Sec-butoxide, and aluminum-n-butoxide.

In obtaining the electrophotographic photoreceptor of the present invention, a solution prepared by dissolving one or more of the above specific organoaluminum compounds in a suitable solvent is applied. At this time, a solution obtained by mixing these organoaluminum compounds with an organosilicon compound may be used. A compound generally called a silane coupling agent is suitable as the organosilicon compound, and examples thereof include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, and γ-glycidoxypropyltrimethoxy. Silane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ
-Aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, diphenyldimethoxysilane, diphenyl Examples thereof include diethoxysilane and monophenyltrimethoxysilane. When such a silane coupling agent is mixed and used, the silane coupling agent is 5 to 50% of the total solid weight.
It is better to be

Thus, a solution containing an organoaluminum compound, and optionally an organosilicon compound, on the photoconductive layer,
The electrophotographic photoreceptor of the present invention can be obtained by applying a method such as spray coating, dip coating, knife coating or roll coating, and then drying and curing. Dry curing temperature is
It can be set to any temperature between 100 and 400 ° C.
The thickness of the finally obtained surface layer may be set arbitrarily, but 0.1 to 10 μm is preferable.

The photoconductive layer mainly composed of amorphous silicon is composed of SiH ₄ , Si ₂ H ₆ , and S.
Formed on the substrate by glow discharge method, sputtering method, ion plating method, vacuum deposition method, etc., using one kind of silicon hydride gas such as i ₃ H ₈ or Si ₄ H ₁₀ or a mixture thereof as a raw material. To do. Among them, plasma CVD (Che
A method of decomposing silane (SiH ₄ ) gas and the like by glow discharge (glow discharge method) by a mical vapor 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, plasma
Separately hydrogen (H ₂ ) in the CVD device at the same time as silane gas, etc.
Gas may be introduced.

What is used as the photoconductive layer of the electrophotographic photoreceptor of the present invention is a semiconductor mainly composed of amorphous silicon containing a hydrogen atom, and the dark resistance of the amorphous silicon photoconductive layer is controlled or charged. Diborane (B ₂ H ₆ ) gas or phosphine (PH ₃ ) gas is mixed into the above gas for the purpose of controlling the polarity, and an impurity element such as boron (B) or phosphorus (P) is added to the photoconductive layer. be able to.

Further, the photoconductive layer may contain at least one kind of carbon atom, nitrogen atom or oxygen atom, and the inclusion of such an atom particularly increases the dark resistance of the photosensitive layer film, increases the photosensitivity, Furthermore, it is preferable from the viewpoint of increasing the charging ability (charging potential per unit film thickness). Further, an element such as germanium (Ge) may be added to the photoconductive layer film for the purpose of increasing the sensitivity of the photoconductor in the long wavelength region. In addition, dark resistance can be increased by adding a halogen atom.

Thus, in order to prepare the photoconductive layer of the electrophotographic photosensitive member of the present invention, in the plasma CVD apparatus, a silicon hydride gas as the main raw material, further using hydrogen gas as desired, together with those gases, Glow discharge decomposition may be performed by introducing a gaseous compound containing a necessary element. The discharge conditions effective for forming the photoconductive layer made of amorphous silicon by the plasma CVD method as described above are, for example, in the case of AC discharge, the frequency is usually 0.1 to 30 MHz, and the vacuum degree at the time of discharge is 0.1 to 30 MHz. 5Torr,
The substrate heating temperature is 100 to 400 ° C. Therefore, the film 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 a paper which has been made conductive can be used. In addition, the shape of the conductive substrate can be any shape such as a cylindrical shape, a flat plate shape, and an endless belt shape.

Examples Next, the electrophotographic photoreceptor of the present invention will be further described 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, and the substrate temperature was set to a predetermined temperature.
Maintaining the temperature at 0 ° C, 100% silane (SiH ₄ ) gas at 120 cc / min, 100 ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen at 20 cc / min, and 100% hydrogen (H ₂ ) gas at 100 ° C. Flow in the range of 90 cc per minute and maintain the internal pressure of the reaction tank at 0.5 Torr.
High-frequency power of 3.56MHz was applied to cause glow discharge, and the output of the high-frequency power supply was maintained at 85W. Thus, a photoreceptor having a photoconductive layer composed of an i-type semiconductor having a high dark resistance, which is mainly composed of amorphous silicon having a thickness of 25 μm and which contains a small amount of boron atoms as impurities, is formed on a cylindrical Al substrate. Obtained.

The photoconductor thus obtained was placed in a copying machine, and the image quality was evaluated by a positive corona charging method. As a result, an image density of practically no problem was obtained in the initial stage, but the image density was gradually increased as the copying operation was repeated. The image density decreased. In addition, when the image quality of this photoconductor was evaluated in an environment of 30 ° C. and 85% RH, the image flow was observed from the initial stage.

Example 1: Aluminum tris was formed on a photoconductor having a photoconductive layer made of an i-type semiconductor containing amorphous silicon as a main component and a slight amount of boron as an impurity, which was prepared under the same method and under the same conditions as in Comparative Example 1. Apply a solution consisting of 1 part by weight of acetylacetonate and 30 parts by weight of isopropyl alcohol at 200 ° C.
After drying and curing for 1 hour in the oven, a photoreceptor having a surface layer having a thickness of 0.1 μm was obtained. The obtained surface layer had properties similar to those of ceramics, and almost did not impair the surface hardness, wear resistance, and heat resistance, which are excellent characteristics of amorphous silicon.

The photoconductor thus obtained was placed in a copying machine, and image quality was evaluated by a positive corona charging method. As a result, an image density practically no problem was obtained in the initial stage. The copying operation was repeated 50,000 times, but no decrease in image density was observed. The image quality of this photoconductor was evaluated in an environment of 30 ° C and 85% RH, but no image flow was observed and high resolution was shown. At the same time, the copy test conducted with the negative corona charging method gave good results as in the case of the positive charging method.

Comparative Example 2: A cylindrical Al substrate was placed at a predetermined position in the reaction chamber of a capacitively coupled plasma CVD apparatus, and the substrate temperature was set to a predetermined temperature.
Maintain at 0 ° C., 100% silane (SiH ₄ ) gas at 120 cc / min, 500 ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen at 30 cc / min, and 100% hydrogen (H ₂ ) gas at every minute in the reaction chamber. The flow rate was 80 cc, and the internal pressure of the reaction tank was maintained at 0.5 Torr.
Turn on high frequency power of z to cause glow discharge,
The output of the high frequency power supply was maintained at 85W. In this way
A photoconductor having a thickness of 25 μm and having a photoconductive layer made of a p-type semiconductor mainly containing amorphous silicon and containing boron as an impurity was obtained on a cylindrical Al substrate.

The photoconductor thus obtained was placed in a copying machine, and the image quality was evaluated by a positive corona charging method. As a result, an image density of practically no problem was obtained in the initial stage, but the image density was gradually increased as the copying operation was repeated. The image density decreased. In addition, when the image quality of this photoconductor was evaluated in an environment of 30 ° C. and 85% RH, the image flow was observed from the initial stage.

Example 2: Aluminium-Sec-butoxide 1 was formed on a photoconductor having a photoconductive layer made of a p-type semiconductor containing amorphous silicon as a main component and containing boron, which was prepared under the same method and under the same conditions as in Comparative Example 2. A solution consisting of 40 parts by weight of ethyl alcohol and 40 parts by weight of ethyl alcohol is applied by dip coating, dried and cured at 200 ° C. for 1 hour, and 0.2 μm
A photoreceptor having a thick surface layer was obtained. The obtained surface layer had properties similar to those of ceramics, and the surface hardness, wear resistance, and heat resistance, which were the excellent characteristics of amorphous silicon, were hardly impaired.

The photoconductor thus obtained was placed in a copying machine, and image quality was evaluated by a positive corona charging method. As a result, an image density practically no problem was obtained in the initial stage. The copying operation was repeated 50,000 times, but no decrease in image density was observed. The image quality of this photoconductor was evaluated in an environment of 30 ° C and 85% RH, but no image flow was observed and high resolution was shown.

Comparative Example 3: A cylindrical Al substrate was placed at a predetermined position in the reaction chamber of a capacitively coupled plasma CVD apparatus, and the substrate temperature was set to a predetermined temperature.
Maintaining at 0 ℃, 100cc silane (SiH ₄ ) gas 120cc / min, 300ppm phosphine (PH ₃ ) gas diluted with hydrogen 30cc / min, and 100% hydrogen (H ₂ ) gas 80cc / min in the reaction chamber. Flowed in to maintain an internal pressure of 0.5 Torr in the reaction chamber, and then 13.56 MH
Turn on high frequency power of z to cause glow discharge,
The output of the high frequency power supply was maintained at 85W. In this way
A photoconductor having a thickness of 25 μm and having a photoconductive layer made of an n-type semiconductor mainly containing amorphous silicon and containing phosphorus as an impurity was obtained on a cylindrical Al substrate.

The image thus obtained was placed in a copying machine, and the image quality was evaluated by a negative corona charging method. In the initial stage, an image density that was not a problem in practical use was obtained. The image density decreased. In addition, this photoreceptor
When the image quality was evaluated under the environment of 30 ° C. and 85% RH, the image flow was observed from the beginning.

Example 3: Aluminium-Sec-butoxide 1 was formed on a photoconductor having a photoconductive layer made of an n-type semiconductor containing amorphous silicon as a main component and containing phosphorus, which was prepared by the same method and under the same conditions as in Comparative Example 3. By weight, a solution consisting of 1 part by weight of methyltrimethoxysilane, 30 parts by weight of isopropyl alcohol, and 30 parts by weight of ethyl alcohol is dip-coated, dried and cured at 200 ° C. for 1 hour, and a photoreceptor having a surface layer of 0.2 μm thickness Got The obtained surface layer had properties similar to those of ceramics, and the surface hardness, wear resistance, and heat resistance, which were the excellent characteristics of amorphous silicon, were hardly impaired.

The photoconductor thus obtained was placed in a copying machine and image quality was evaluated by a negative corona charging method. As a result, an image density practically no problem was obtained in the initial stage. The copying operation was repeated 50,000 times, but no decrease in image density was observed. The image quality of this photoconductor was evaluated in an environment of 30 ° C and 85% RH, but no image flow was observed and high resolution was shown.

EFFECT OF THE INVENTION The electrophotographic photoreceptor of the present invention retains the excellent characteristics of the photoreceptor made of amorphous silicon, that is, high mechanical strength, high durability, high heat resistance, and high photosensitivity. It has a high charge retention power without being affected by the number of times of use and can provide an image of excellent quality.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasunori Okugawa 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. Takematsu Plant (72) Inventor Yasuo Ro, 1600 Takematsu, Minamiashigara, Kanagawa Fuji Xerox Co., Ltd. Takematsu Inside the factory (72) Inventor Tokuyoshi Takahashi 1600 Takematsu, Minamiashigara City, Kanagawa Fuji Xerox Co., Ltd. Takematsu Factory (56) Reference JP 59-223444 (JP, A) JP 59-223446 (JP, A) JP-A-59-102240 (JP, A) JP-A-62-201457 (JP, A)

Claims (1)

[Claims] 1. A photoconductor for electrophotography comprising a photoconductive layer and a surface layer sequentially laminated on a conductive substrate, wherein the photoconductive layer is formed of a semiconductor mainly containing amorphous silicon containing hydrogen atoms. Wherein the surface layer is a dry-cured product of a solution containing at least one aluminum acetylacetonate complex or aluminum alkoxide.