JPH0727256B2 - Electrophotographic photoconductor - Google Patents

Description

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

(Prior Art) In electrophotography, an electrostatic latent image is formed on a photoconductor by charging and imagewise exposure, and after developing the latent image with a developer called toner,
In this method, a toner image is transferred onto a transfer paper and fixed to obtain a copy. The photoconductor used in this electrophotographic method has a basic structure in which a photosensitive layer is laminated on a conductive substrate. However, conventionally, as a material for forming the photosensitive layer, an inorganic photosensitive material such as selenium or selenium alloy, cadmium sulfide, or zinc oxide, or an organic material such as polyvinylcarbazole, trinitrofluorenone, bisazo pigment, phthalocyanine, pyrazoline, or hydrazone. Photosensitive materials are known and are used as a single layer or a laminated photosensitive layer.
However, these conventionally used photosensitive layers still have problems to be solved in terms of durability, heat resistance and photosensitivity.

(Problems to be Solved by the Invention) 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.

An object of the present invention is to provide an electrophotographic photoconductor that eliminates the above-mentioned drawbacks of the photoconductor 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.

(Means and Actions for Solving Problems) As a result of intensive studies, the present inventor has coated a photoconductive layer made of amorphous silicon on a conductive substrate, and further provided a surface layer on the photoconductive layer. It was found that the above-mentioned object can be achieved by laminating and using a dry-cured product of a solution containing at least one acetylacetonato complex of titanium or alkoxide of titanium as the surface layer. 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 composed of a semiconductor, and the surface layer is a dry-cured product of a solution containing at least one acetylacetonato complex of titanium or alkoxide of titanium.

Preferred examples of the titanium acetylacetonato complex or titanium alkoxide used for forming the surface layer of the electrophotographic photoreceptor of the present invention include diisopropoxytitanium bis (acetylacetonate) and titanium as the central metal. Acetylacetonate polynuclear complex, bis (acetylacetonate) titanium oxide, titanium tetramethoxide, titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, etc. Can be mentioned.

To obtain the electrophotographic photoreceptor of the present invention, a solution prepared by dissolving one or more of the above-mentioned organic titanium compounds in a suitable solvent is applied. At this time, a solution obtained by mixing these organotitanium 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 Examples thereof include ethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, diphenyldimethoxysilane, 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 organotitanium 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 ~ 4
It can be set to any temperature between 00 ° C. The thickness of the finally obtained surface layer can be set arbitrarily, but 0.1
-10 μm, especially 1 μm or less 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, but containing a boron atom or a phosphorus atom as an impurity to form an n-type, It can be a complete i-type or p-type semiconductor. Diborane (B ₂ H ₆ ) gas is usually used as a raw material for the addition of the boron atom, and the p-type semiconductor is added to the p-type semiconductor in the range of 10 ⁻³ to 10 ^{−2 at} %. When added, complete i-type semiconductor amorphous silicon is obtained. The addition of phosphorus atoms is usually
Phosphine (PH ₃ ) gas is used as a raw material, 10 ^-6 ~ 1
Amorphous silicon, which is an n-type semiconductor, is obtained by adding about 0 ^-1 atomic%. The photoconductive layer of the present invention does not contain impurities for controlling the conductivity type, but it is well known that the amorphous silicon is i-type which shows a slight n-type tendency when boron atoms are not included. Has been.

Further, a halogen atom or the like may be contained in the photosensitive layer film for the purpose of increasing the dark resistance of the photosensitive layer film, increasing the photosensitivity or 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.

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.

(Example) 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 placed at a predetermined position in a 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 3.57MHz 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 made of an i-type semiconductor having a thickness of 25 μm as a main component and containing amorphous silicon and containing boron atoms as impurities 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, this photoreceptor is 30 ℃, 85%
When the image quality was evaluated under the RH environment, the flow of images was observed from the beginning.

Example 1: Diisopropoxytitanium bis was formed on a photoreceptor having a photoconductive layer made of an i-type semiconductor containing amorphous silicon as a main component and boron as an impurity, which was prepared under the same method and under the same conditions as in Comparative Example 1. (Acetylacetonate) 1 part by weight, n
-Apply a solution consisting of 20 parts by weight of butyl alcohol,
It was dried and hardened in an oven at 0 ° C. for 1 hour to obtain a photoreceptor having a surface layer with a thickness of 0.1 μm. The surface layer thus obtained 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.

When this photoreceptor was placed in a copying machine and the image quality was evaluated by a positive corona charging method, an image density that was 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. This photoconductor is 30 ℃, 85%
The image quality was evaluated under the RH environment, but no image flow was observed and the resolution was high. 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 the temperature at 0 ° C, 100% silane (SiH ₄ ) gas in the reaction chamber at 120cc per minute, 500ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen at 20cc per minute, and 100% hydrogen (H ₂ ) gas at every minute Flow in the range of 80 cc / min and maintain the internal pressure of the reaction tank at 0.5 Torr.
A 3.56MHz high frequency power supply was turned on to cause glow discharge, and the output of the high frequency power supply was maintained at 85W. In this way, a photoconductor having a photoconductive layer made of a p-type semiconductor having a thickness of 25 μm as a main component and containing amorphous silicon and containing boron atoms as impurities 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, this photoreceptor is 30 ℃, 85%
When the image quality was evaluated under the RH environment, the flow of images was observed from the beginning.

Example 2: A titanium tetraethoxide 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 as an impurity, which was prepared by the same method and under the same conditions as in Comparative Example 2. 1 part by weight, isopropyl alcohol 30
A solution of 1 part by weight was applied and dried and hardened in an oven at 200 ° C. for 1 hour to obtain a photoreceptor having a surface layer of 0.3 μm thick. The surface layer thus obtained 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.

When this photoreceptor was placed in a copying machine and the image quality was evaluated by a positive corona charging method, an image density that was 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. This photoconductor is 30 ℃, 85%
The image quality was evaluated under the RH environment, but no image flow was observed and the resolution was high.

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 the temperature at 0 ° C, 100% silane (SiH ₄ ) gas at 120 cc / min, 300 ppm phosphine (B ₂ H ₆ ) gas diluted with hydrogen at 30 cc / min, and 100% hydrogen (H ₂ ) gas at 100 ° C. The flow rate was 80 cc, and the internal pressure of the reactor was maintained at 0.5 Torr. Then, a 13.56 MHz high frequency power supply was turned on to cause glow discharge, and the output of the high frequency power supply was maintained at 85 W. In this way, a photoconductor having a photoconductive layer made of an n-type semiconductor having a thickness of 25 μm as a main component and containing amorphous silicon as the impurity on a cylindrical Al substrate was obtained. The image thus obtained was placed in a copying machine and the 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 image density decreased. In addition, this photoreceptor is
When the image quality was evaluated under the environment of% RH, the image flow was observed from the initial stage.

Example 3: A titanium tetrabutoxide film was formed on a photoconductor having a photoconductive layer made of an n-type semiconductor containing amorphous silicon as a main component and containing a phosphorus atom as an impurity, prepared in the same manner and under the same conditions as in Comparative Example 3. A solution consisting of 1 part by weight of side, 1 part by weight of γ-acrylogin propyltrimethoxysilane, 10 parts by weight of methyl alcohol, and 20 parts by weight of isopropyl alcohol is applied, dried and hardened in an oven at 200 ° C for 1 hour, and has a thickness of 0.3μ. A photoconductor having a surface layer of The surface layer thus obtained 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.

When this photoreceptor was placed in a copying machine and the image quality was evaluated by a negative corona charging method, an image density that was practically no problem was obtained at the initial stage. The copying operation was repeated 50,000 times, but no decrease in image density was observed. This photoconductor is 30 ℃, 85%
The image quality was evaluated under the RH environment, but no image flow was observed and the resolution was high.

(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-59-102247 (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. The electrophotographic photoreceptor, wherein the surface layer comprises a dry-cured product of a solution containing at least one acetylacetonato complex of titanium or alkoxide of titanium.