JPH0721647B2 - 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 forms an electrostatic latent image on a photoconductor by charging it and exposing it to light, and after developing this 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 constituting the photosensitive layer, selenium or selenium alloy, cadmium sulfide, an inorganic photosensitive material such as zinc oxide, or polyvinylcarbazole, trinitrofluorenone, bisazo pigment, phthalocyanine, pyrazoline, hydrazone and the like organic material. Photosensitive materials are known and are used as a single layer or a laminated photosensitive layer.

Problems to be Solved by the Invention However, these conventionally used photosensitive layers still have problems to be solved in terms of durability, heat resistance, photosensitivity and the like.

In recent years, photoreceptors using amorphous silicon (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 friction, 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 for Solving the Problems As a result of earnest research, the present inventor has laminated an intermediate layer on a conductive substrate and coating a photoconductive layer made of amorphous silicon on the intermediate layer. It has been found that the above object can be achieved by using, as the intermediate layer, a dried and cured product of a solution containing at least one organic titanium compound. As the photoconductive layer, a semiconductor mainly containing amorphous silicon containing hydrogen atoms is used.

Thus, according to the present invention, in the electrophotographic photosensitive member formed by sequentially laminating the intermediate layer and the photoconductive layer on the conductive substrate, the photoconductive layer is mainly composed of amorphous silicon containing a hydrogen atom. An electrophotographic photoreceptor is provided, which is made of a semiconductor, and the intermediate layer is a dried and cured product of a solution containing at least one organic titanium compound.

Although various kinds of organic titanium compounds can be used for forming the intermediate layer of the electrophotographic photosensitive member of the present invention, titanium complexes and titanium alkoxides are particularly preferable. Preferred examples thereof include diisopropoxy titanium bis (acetylacetonate), polynuclear acetylacetonate having titanium as a central metal, bis (acetylacetonate) titanium oxide, titanium tetramethoxide, titanium tetraethoxide, titanium. And tetra-n-propoxide, titanium tetra-iso-propoxide, titanium tetrabutoxide, titanium tetra-iso-butoxide, and the like.

In obtaining the electrophotographic photoreceptor of the present invention, a solution prepared by dissolving one or more of the above organic titanium compounds in a suitable solvent is applied. At this time, a solution obtained by mixing these organic titanium compounds with an organic silicon 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-chloropropylmethoxysilane, γ -Mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, monophenylto Silane and the like. 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 placed on the conductive substrate.
The electrophotographic photoreceptor of the present invention can be obtained by applying by a method such as spray coating, dip coating, knife coating or roll coating, followed by drying and curing and laminating a photoconductive layer thereon. The dry curing temperature can be set to any temperature between 100 and 400 ° C. The thickness of the finally obtained intermediate 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 Si ₃
It is formed on the intermediate layer by a method such as a glow discharge method, a sputtering method, an ion plating method, or a vacuum deposition method using one kind of hydrogen silicon gas such as H ₈ or Si ₄ H ₁₀ or a mixture thereof as a raw material. 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. In terms of film growth rate,
It is preferable to use SiH ₄ and Si ₂ H ₆ .

What is used as the photoconductive layer of the electrophotographic photoreceptor of the present invention is a semiconductor mainly composed of amorphous silicon containing hydrogen atoms.

Diborane (B ₂ H ₆ ) was added to the above gas for the purpose of controlling the dark resistance or charging polarity of the amorphous silicon photosensitive layer film.
Gas or phosphine (PH ₃ ) gas mixed into the photoconductive layer for boron (B) or. An impurity element such as phosphorus (P) can be added.

In addition, halogen atoms, carbon atoms, oxygen atoms, nitrogen atoms, etc. in the photosensitive layer film are used 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). May be included.

Further, an element such as germanium (Ge) can 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 ~ 400 ℃. Therefore, the film thickness of the photoconductive layer mainly composed of amorphous silicon is 1 to 100 μm,
In particular, the thickness is preferably 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 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 3.56MHz was applied to cause glow discharge, and the output of the high-frequency power supply was maintained at 85W. Thus, the amorphous silicon having a thickness of 25 μm is mainly formed on the cylindrical Al substrate, and it has a high resistance including hydrogen and a trace amount of boron.
Thus, a photoconductor having a photoconductive layer made of a type semiconductor 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.

Example 1: On a cylindrical Al substrate having the same shape as in Comparative Example 1, 1 part by weight of diisopropoxytitanium bis (acetylacetonate), n
-Dip-coat a solution consisting of 20 parts by weight of butanol and
It was dried in an oven at 0 ° C. for 2 hours to provide an intermediate layer having a thickness of 0.4 μm. Then, on this intermediate layer, a photoconductive layer mainly containing amorphous silicon and having the same content as in Comparative Example 1 was provided by the same method as in Comparative Example 1 to have a film thickness substantially the same as in Comparative Example 1. The photoconductive layer thus obtained has properties similar to ceramics,
The excellent characteristics of amorphous silicon, surface hardness, wear resistance,
It had heat resistance as it was.

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. 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, 500ppm diborane (B ₂ H ₆ ) gas diluted with hydrogen at 30 cc / min, and 100% hydrogen (H ₂ ) gas at every minute. 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 photoconductive layer composed of a p-type semiconductor mainly containing amorphous silicon and having a thickness of 25 μm on a cylindrical Al substrate was obtained.

The image thus obtained was put in a copying machine and image quality was evaluated by a positive corona charging method. As a result, an image density that could be practically used was not obtained.

Example 2 A solution of 1 part by weight of [titanium tetraethoxide] and 30 parts by weight of isopropyl alcohol was dip-coated on a cylindrical Al substrate having the same shape as in Comparative Example 2 and dried in a furnace at 250 ° C. for 2 hours. Then, an intermediate layer having a thickness of 0.3 μm was provided. Next, on this intermediate layer, by the same method as in Comparative Example 2, a photoconductive layer containing amorphous silicon as a main component and having the same content as in Comparative Example 2 was provided with a film thickness substantially the same as in Comparative Example 2.

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.

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. Thus, 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 hydrogen and phosphorus was obtained on a cylindrical Al substrate.

The image thus obtained was put into a copying machine and image quality was evaluated by a negative corona charging method. As a result, an image density that could withstand practical use was not obtained.

Example 3: On a cylindrical Al substrate having the same shape as in Comparative Example 3, 1 part by weight of [titanium tetrabutoxide], 1 part by weight of γ-acryloxypropyltrimethoxysilane and 10 parts of methyl alcohol were used.
A solution consisting of 20 parts by weight of isopropyl alcohol and 30 parts by weight of the solution is applied by dipping, and dried in an oven at 250 ° C for 2 hours to give a thickness of 0.3 μm.
A thick intermediate layer was provided. Next, on this intermediate layer, Comparative Example 3
A photoconductive layer mainly composed of amorphous silicon and having the same content as in Comparative Example 3 was provided in the same thickness as in Comparative Example 3 by the same method as in.

The photoconductor thus obtained was placed in a copying machine and subjected to image quality evaluation by a corona charging system of the prefecture. 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.

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) References JP 59-223439 (JP, A) JP 59-223441 (JP, A) JP-A-58-93062 (JP, A)

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising an intermediate layer and a photoconductive 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 intermediate layer is formed of a dried and cured product of a solution containing at least one organic titanium compound.