JPH0727259B2 - 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 tin acetylacetonate complex or tin alkoxide. An i-type 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. A solution containing at least one kind of carbon atom, nitrogen atom or oxygen atom, wherein the surface layer contains at least one kind of tin acetylacetonate complex or tin alkoxide. There is provided an electrophotographic photosensitive member comprising the dried and cured product of

Preferred examples of the tin acetylacetonate complex or tin alkoxide used for forming the surface layer of the electrophotographic photoreceptor of the present invention include tin bisacetylacetonate, tin tetramethoxide, tin tetraethoxide, Examples include tin tetraisopropoxide, tin tetrabutoxide, and tin tetra-Sec-butoxide.

In obtaining the electrophotographic photoreceptor of the present invention, a solution prepared by dissolving one or more of the above specific organotin compounds in a suitable solvent is applied. At this time, a solution obtained by mixing these organotin 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-aminopropyltrimethoxysilane Ethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, diphenyldimethoxysilane,
Examples thereof include diphenyldiethoxysilane and monophenyltrimethoxysilane. When such a silane coupling agent is mixed and used, it is preferable that the silane coupling agent accounts for 5 to 50% of the total solid weight.

Thus, a solution containing an organotin compound, and optionally an organosilicon compound, is applied onto the photoconductive layer by a method such as spray coating, dip coating, knife coating or roll coating, and then dried and cured to form a solution. The electrophotographic photoreceptor of the invention can be obtained. Dry hardening temperature is 100 ~ 400
It can be set to any temperature between ° C. The film thickness of the finally obtained surface layer can also be set arbitrarily, but 0.1 to 1
0 μm is preferable.

The photoconductive layer mainly composed of amorphous silicon is composed of SiH ₄ , Si ₂ H ₆ , and S.
Formed on a substrate by a glow discharge method, a sputtering method, an ion plating method, a vacuum deposition method or the like using one kind of a 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 so-called i-type semiconductor mainly containing amorphous silicon containing hydrogen atoms. Note that it is preferable to add a trace amount of boron so as to obtain a more i-type semiconductor. For the addition of the boron atom, diborane (B ₂ H ₆ ) gas is usually used as a raw material, and the addition amount of the boron atom is It is preferably about 10 to 100 ppm.

Further, in the electrophotographic photoreceptor according to the present invention, the photoconductive layer further contains at least one kind of carbon atom, nitrogen atom or oxygen atom. The inclusion of such atoms is particularly preferable from the viewpoint of increasing the dark resistance of the photosensitive layer film, increasing the photosensitivity, and further 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 at 0 ℃, 100cc silane (SiH ₄ ) gas 120cc / min, 100ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen 20cc / min, 100% ethylene (C ₂ H ₄ ) gas in the reaction chamber. Inject 12 cc / min and 100% hydrogen (H ₂ ) gas in the range of 88 cc / min,
After maintaining the internal pressure of the reactor at 0.5 Torr, high frequency power of 13.56 MHz was applied to cause glow discharge, and the output of the high frequency power source was maintained at 85 W. Thus, a photoconductor having a thickness of 25 μm and having a photoconductive layer composed of an i-type semiconductor mainly containing amorphous silicon and having a trace amount of boron atoms and further carbon atoms on a cylindrical Al substrate was 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: 1 part by weight of tin bisacetylacetonate was formed on a photoreceptor having a photoconductive layer made of an i-type semiconductor mainly composed of amorphous silicon, which was prepared under the same method and under the same conditions as in Comparative Example 1.
Methyltrimethoxysilane 1 part by weight, methyl alcohol
A solution consisting of 20 parts by weight and 30 parts by weight of isopropyl alcohol is applied by dip coating, dried and hardened in an oven at 200 ° C for 1 hour, and then 0.2
A photoreceptor having a μ-thick surface layer was obtained. The surface layer thus obtained had properties similar to those of ceramics, and did not impair the surface hardness, wear resistance, and heat resistance, which are the 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.
Maintaining 0 ° C, 100% silane (SiH ₄ ) gas at 120cc / min, 100ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen at 20cc / min, and 100% nitrogen (N ₂ ) gas in the reaction chamber. 85 cc / min, and 100% hydrogen (H ₂ ) gas was flown in at 15 cc / min, and after maintaining the internal pressure of the reaction tank at 0.5 Torr, high-frequency power of 13.56 MHz was applied to cause glow discharge, The output of the high frequency power supply was maintained at 85W. In this way, a photosensitive layer having a photoconductive layer composed of an i-type semiconductor having a thickness of 25 μm, mainly amorphous silicon, and a slight amount of boron as an impurity and nitrogen (N ₂ ) on a cylindrical Al substrate in this manner. Got the body

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: Tin was formed on a photoreceptor having a photoconductive layer made of an i-type semiconductor containing amorphous silicon as a main component and a slight amount of boron and nitrogen, which was prepared under the same method and under the same conditions as in Comparative Example 2. A solution consisting of 2 parts by weight of tetraisopropoxide, 1 part by weight of dimethyldimethoxysilane, and 40 parts by weight of ethyl alcohol is dip-coated, dried and hardened at 200 ° C. for 1 hour, and has a thickness of 0.3 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 the 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 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.
Maintain at 0 ℃, 100cc silane (SiH ₄ ) gas 120cc / min, 100ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen 20cc / min, and 100% oxygen (O ₂ ) gas in the reaction chamber. 1.0 cc per minute.
Furthermore, 100% hydrogen (H ₂ ) gas was flowed in at 99 cc / min, and after maintaining the internal pressure of the reaction tank at 0.5 Torr, high frequency power of 13.56 MHz was applied to cause glow discharge, causing high frequency power supply. The output was maintained at 85W. In this way, the cylindrical Al
A photoconductor having a thickness of 25 μm and having a photoconductive layer composed of an i-type semiconductor having a thickness of 25 μm as a main component, amorphous silicon as a main component, and a trace amount of boron as an impurity was 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 practically no problem was obtained in the initial stage. The image density gradually 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 3: Tin was formed on a photoconductor having a photoconductive layer made of an i-type semiconductor containing amorphous silicon as a main component and a small amount of boron and oxygen, which was prepared under the same method and conditions as in Comparative Example 3. 2 parts by weight of tetrabutoxide, 1 part by weight of γ-acryloxypropyltrimethoxysilane, 20 parts by weight of methyl alcohol,
Dip coating a solution consisting of 30 parts by weight of ethyl alcohol,
It was dried and cured at 200 ° C. for 1 hour to obtain a photoreceptor having a surface layer having a thickness of 0.2 μm. 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 the 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. The copy test performed with the negative corona charging method also gave good results, as with the positive charging method.

(Effects 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, and It has a high charge retention ability without being affected by the environment and 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 an i-type mainly composed of amorphous silicon containing hydrogen atoms. Dry curing of a solution composed of a semiconductor and further containing at least one kind of carbon atom, nitrogen atom or oxygen atom, and the surface layer containing at least one kind of tin acetylacetonate complex or tin alkoxide. A photoconductor for electrophotography, which is characterized by comprising a thing.