JPS6161381B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to light (here, light in the sense of light, which refers to ultraviolet rays, visible rays, infrared rays, X-rays, γ-rays, etc.)
The present invention relates to a method for producing an electrophotographic imaging member which is sensitive to electromagnetic radiation such as, and which can be imaged by electrostatic imaging processing. [Prior Art] The photoconductive material constituting the photoconductive layer in an electrophotographic image forming member, etc. must have high sensitivity, high resistance, and spectral characteristics as close as possible to the luminous sensitivity. It is important that there is no pollution to the human body during use. However, inorganic photoconductive materials such as Se, CdS, and ZnO, poly-N vinyl carbazole (PVK), and trinitrofluorenone (TNF) are photoconductive materials that constitute the photoconductive layer of conventional electrophotographic image forming members. It is difficult to assert that organic photoconductive materials (OPCs) such as those described above necessarily satisfy all of the above-mentioned conditions to a higher level. For example, in an electrophotographic image forming member using Se as a photoconductive layer-forming material, Se alone has a narrow spectral sensitivity range when using light in the visible light region, so Te or As is added to produce a spectral sensitivity. The aim is to expand the sensitivity range. However, such an electrophotographic image forming member having a Se-based photoconductive layer containing Te or As suffers from large optical fatigue, so if the same original is continuously copied, the image of the copied image will be distorted. This may cause a decrease in density or background stains (fogging on white areas),
Furthermore, when another document is subsequently copied, the image of the previous document is copied as an afterimage (ghost phenomenon). However, since Se, especially As and Te, are extremely harmful substances to the human body, it is necessary to devise ways to use manufacturing equipment that does not allow them to come into contact with the human body. Furthermore,
Even after manufacturing, if the photoconductive layer is exposed,
When undergoing processing such as cleaning, the surface of the photoconductive layer is directly rubbed, so some of it is scraped off and gets mixed into the developer, scattered inside the copying machine, or mixed into the copied image. and produce results that cause contact with the human body. Furthermore, when the surface of a Se-based photoconductive layer is continuously and repeatedly exposed to corona discharge many times, crystallization or oxidation occurs near the surface of the layer, leading to deterioration of the electrical properties of the photoconductive layer. There are many cases. Alternatively, if the surface of the photoconductive layer is exposed, when a liquid developer is used to visualize (develop) an electrostatic image, it will come into contact with the solvent, resulting in excellent solvent resistance (currently liquid resistance). However, it is difficult to say with certainty that the Se-based photoconductive layer always satisfies this requirement. In addition, the Se-based photoconductive layer is formed in an amorphous state in order to have high dark resistance as a photoconductive layer of an electrophotographic image forming member, but Se crystallization occurs at an extremely low temperature of approximately 65°C. Therefore, crystallization occurs during handling after manufacturing or during use, and is greatly affected by the ambient temperature and frictional heat caused by rubbing with other parts during the image forming process. However, it also has a drawback in terms of heat resistance, in that it tends to cause a decrease in dark resistance. On the other hand, an image forming member having a so-called binder-based photoconductive layer using ZnO, CdS, etc. as a photoconductive layer constituent material is advantageous in manufacturing compared to an image forming member having an Se-based photoconductive layer. It is possible to reduce the manufacturing cost. However, because the binder-based photoconductive layer must be formed by uniformly dispersing photoconductive material particles in a resin binder, the electrical and photoconductive properties of the photoconductive layer There are many parameters that determine the physical and chemical properties, and it cannot be formed with good reproducibility, resulting in a decrease in yield and a lack of mass productivity. Furthermore, due to the unique nature of the binder-based photoconductive layer being a dispersed system, the entire layer is porous, and as a result, it is highly dependent on humidity, resulting in deterioration of electrical properties when used in a humid atmosphere. In many cases, it becomes impossible to obtain a copy of the image. Furthermore, the porous nature of the photoconductive layer causes developer to enter the layer during development, which not only reduces mold releasability and cleaning properties but also causes unusability. Furthermore, when using CdS, since CdS itself has an effect on the human body, it is necessary to prevent it from coming into contact with the human body or scattering into the surrounding environment. When using ZnO, ZnO
Binder-based photoconductive layers have drawbacks such as low photosensitivity, narrow spectral sensitivity range, significant optical fatigue, and poor photoreactivity. In addition, electrophotographic image forming members using organic photoconductive materials such as PVK and TNF, which have been attracting attention recently, lack moisture resistance, corona ion resistance, and cleaning properties, and also have low light sensitivity and visible It has drawbacks such as a narrow spectral sensitivity region in the optical region and is biased towards short wavelengths, and is therefore of use only within an extremely limited range. However, some of these organic photoconductive materials are suspected of being carcinogenic.
Many of them are not guaranteed to be completely harmless to the human body. Therefore, there is a need for a third material that can provide an excellent photoconductive member that overcomes the above-mentioned problems. Among the materials that have recently been viewed as promising as such materials is amorphous silicon (hereinafter a-Si).
). In the early stages of development, a-Si films exhibited various electrical and optical properties due to their structure being influenced by the manufacturing method and manufacturing conditions, which caused major problems in terms of reproducibility. I was holding it. However, in early 1976, it was reported that p-n junctions could be realized in a-Si for the first time in amorphous materials (Applied Physics Letter; it was thought that p-n control was impossible in amorphous materials).
Vol. 28, No. 2, 15January, 1976), there has been a great deal of interest in this technology, and research and development efforts have since focused primarily on its application to solar cells. For this reason, the a-Si films reported so far are
Since it was developed for use in solar cells, it cannot currently be used as a photoconductive layer in electrophotographic image forming members or image pickup tubes due to its electrical and optical properties. be. That is, the solar cell is
Since solar energy is extracted by converting it into the form of current, the resistance of the a-Si film must be relatively small in order to have a good signal-to-noise ratio [photocurrent (ip)/dark current (id)] and to extract current efficiently. However, if the resistance is too small, the photosensitivity will decrease and the signal-to-noise ratio will deteriorate, so one of the characteristics is that the resistance should be 10 ⁵ to 10 ⁸
Approximately Ω・cm is required. However, the a-Si film, which has this moderate resistance (dark resistance: resistance in a dark place), has too little resistance (dark resistance) to be used as a photoconductive layer of an electrophotographic image forming member.
is so low that it cannot be used at all by applying currently known electrophotographic methods. In addition, previous reports ^on a-Si films have shown that increasing the dark resistance decreases the photosensitivity. In this respect as well, the conventional a-Si film could not serve as a photoconductive layer of an electrophotographic image forming member. In addition, when the a-Si film developed for conventional solar cells is subjected to charging treatment on its surface for electrostatic image formation, the charge retention ability on the charged surface is low;
Dark decay is extremely fast, so it lacks versatility. In addition, such a-Si films are highly dependent on the external environment, especially humidity, and in a humid atmosphere,
Charging characteristics tend to deteriorate significantly. The present invention has been made in view of the above-mentioned points, and is based on amorphous silicon hydride (hereinafter a-
From the perspective of applying Si:H (abbreviated as Si:H) to electrophotography, we have repeatedly conducted experiments to improve the electrophotographic properties of the a-Si:H layer, which has a specific surface condition. The invention was based on the discovery that the photoconductive layer is extremely excellent as a photoconductive layer. That is, from the viewpoint of improving the surface electrical properties of the a-Si:H layer, we measured and analyzed the charging properties of the a-Si:H layer formed by variously changing the molecular species adsorbed on the surface. As a result, a surface adsorption layer formed by adsorbing a molecular species that satisfies a certain relationship on the surface of the a-Si:H layer exhibits extremely good charging characteristics, is versatile, and has charge retention ability. The present invention is based on the discovery that it is excellent in A method for producing an electrophotographic imaging member to achieve the intended purpose of the present invention comprises forming on a support a photoconductive layer consisting of amorphous hydrogenated silicon containing hydrogen in an amount of 1 to 40 atomic percent; Next, an adsorption layer of either an electron-accepting molecule or an electron-donating molecule to the amorphous hydrogenated silicon is provided on the surface of the photoconductive layer immediately after its formation. As described above, from a practical point of view, the electrophotographic image forming member obtained by the production method of the present invention is made by adsorbing new molecules that are difficult to desorb onto the surface of the a-Si:H layer. stabilized and, accordingly, a
By forming a new electron distribution inside the -Si:H layer, the charging characteristics during electrostatic image formation are improved. That is, the electrophotographic image forming member obtained by the production method of the present invention stabilizes the surface layer by covering the surface of the a-Si:H layer with adsorbed molecules described below, and also stabilizes the surface layer by covering the surface of the a-Si:H layer with adsorbed molecules, which will be described later. The electrical properties of the surface are controlled by The adsorbed molecules forming the adsorbed layer of the electrophotographic image forming member in the present invention are the a-
An electron-accepting or electron-donating material for Si:H is selected and applied. Therefore, even adsorbed molecules of the same type can exhibit both electron-donating and electron-accepting properties depending on whether a-Si:H is p-type or n-type. In the present invention, the adsorption layer as described above is provided on the surface of the a-Si:H layer by exposing the surface of the a-Si:H layer to an atmosphere of adsorbed molecules. For example, an a-Si:H layer is formed on a support for electrophotography according to predetermined conditions and procedures, and the a-Si:H layer is
-The desired adsorption layer is formed by exposing the Si:H layer, in its fresh state at the time of its formation, to a gas atmosphere of adsorbed molecules for a predetermined period of time, making it a versatile image with excellent charging characteristics. A forming member is provided.
Alternatively, the adsorbed molecules are activated by ionization or plasma formation, and a- is added to the atmosphere of the activated adsorbed molecules.
The surface of the Si:H layer may be exposed and subjected to adsorption layer formation treatment. When these adsorbed molecules are adsorbed onto the surface of the a-Si H layer, the a-Si:H layer may be heated and maintained at a predetermined temperature. In the present invention, when an adsorbed molecule layer is provided on the surface of an a-Si:H layer formed on a desired support with a desired layer thickness and area, the adsorbed molecules are electron-donating adsorbed molecules. , such as NH ₃ ; H ₂ O; naphthalene; bisphenyl; fluorenone; acetracene; phenanthrene; acenaphthrene; acenaphthylene; chrysene; pyrene; 1,4-dimethoxybenzene; diphenylamine; 2,2'-dinaphthylamine; 1,5-diethoxy Naphthalene; 2-
Phenylindole; Carbazole; Phenothiazine; 2,4-bis(4'-diethylaminophenyl)-1,3,4-oxydiazole; 2,4-
Bis(4'-diethylaminophenyl)-1・3・
A number of compounds similar to these, including 4-triazole, etc., are effective, and electron-accepting adsorption molecules include O ₂ , 1,5-dinitronaphthalene, 1,8-dinitronaphthalene;
4,5-trinitronaphthalene; 2,4,5,7
-tetranitrofluorenone; 1,5-dichloronaphthalene; 1,4-dibromonaphthalene; 9.
10-dibromoanthracene; phthalic anhydride; tetrachlorophthalic anhydride; p-chloranil; 1,2
-Benzanthraquinone; Benzyl; Pyrene-3
-Aldehyde; Many compounds similar to these, including 9-acetylanthracene, etc., are effective. These effective adsorbed molecules are in gaseous or liquid form, and are preferably activated by plasma, ionization, radicalization, etc. to form an a-Si:H layer. is contacted with the immediate surface to form the desired adsorption layer. In the present invention, adsorbent molecules such as those listed above that provide similar properties can also be used by mixing them in a desired ratio. In the present invention, a photoconductive layer formed of a-Si:H is formed on a support described below. For example, stainless steel, Al, Cr, Mo, Au, Ir,
A conductive support such as metals such as Nb, Ta, V, Ti, Pt, Pd or alloys thereof, or these metals,
Vapor-deposited conductive supports, heat-resistant films or sheets of synthetic resins that exhibit heat resistance at least at the temperature during layer formation, and electrically insulating supports such as glass and ceramics are effective. It will be done. The support is subjected to a series of cleaning treatments before the a-Si:H is deposited thereon. In such cleaning treatments, typically, for example, a metallic support is contacted with an alkaline or acidic solution that effectively cleans the surface by etching. Afterwards, the support is dried in a clean atmosphere and, without any further preparatory treatment, is then placed in place in the deposition chamber of an apparatus that deposits a-Si:H onto the support using electrical discharge phenomena. . In the case of an electrically insulating support, its surface is subjected to conductive treatment, if necessary. For example, for glass, In ₂ O ₃ , SnO ₂ , etc.
If the surface is conductive-treated or made of synthetic resin film such as polyimide film, Al, Ag,
Pb, Zn, Ni, Au, Cr, Mo, Ir, Nb, Ta, V,
The surface is treated with a metal such as Ti or Pt by vacuum evaporation, electron beam evaporation, sputtering, etc., or laminated with the metal, so that the surface thereof is conductive. The shape of the support body is cylindrical, belt-shaped,
It may have any shape, such as a plate shape, and the shape is determined as desired. However, in the case of electrophotography, it is preferable to use an endless belt shape or a cylindrical shape for continuous high-speed copying. The thickness of the support is determined as appropriate so that the desired image forming member is formed, but if flexibility is required, the thickness of the support may be determined within a range that allows the support to function adequately. If possible, it will be made as thin as possible. However, in such a case, the thickness is usually set to 10μ or more in view of manufacturing and handling of the support, mechanical strength, etc. The photoconductive layer in the present invention is of the following type a.
-Si:H can be obtained by forming a layer with one type of H, or by selecting at least two types and forming a layer in a state where different types are bonded. N-type: contains only a donor, or contains both a donor and an acceptor, and has a high donor concentration (Nd). p-type...contains only acceptor,
Or one that contains both a donor and an acceptor and has a high acceptor concentration (Na). i type……NaNd0 or Na
Nd's. The a-Si:H layer of type ~ as a layer constituting the photoconductive layer in the present invention is formed by a glow discharge method, a reactive sputtering method, etc.
It is formed by doping an n-type impurity, a p-type impurity, or both impurities into the photoconductive layer made of a-Si:H in a controlled amount. In this case, according to the findings from the experimental results of the present inventors, by adjusting the impurity concentration in the layer within the range of 10 ¹⁵ to 10 ¹⁹ cm ^-3 , stronger n-type (or stronger A weaker n-type (or weaker p-type) a-Si:H can be formed from a strong p-type a-Si:H. The photoconductive layer made of a-Si:H of the type ~ is formed by a glow discharge method, a sputtering method, an ion implantation method, an ion plating method, or the like. A photoconductive layer composed of a-Si:H can have desired properties, and its dark resistance and photoelectric gain are controlled by controlling the amount of H contained during its formation. Here, "H is contained in the photoconductive layer" means "a state in which H is combined with Si",
It means either "a state in which H is ionized and incorporated into the layer" or "a state in which H is incorporated into the layer as H ₂ " or a combination thereof. H to the photoconductive layer consisting of a-Si:H
is contained in the manufacturing equipment system when forming the layer.
Introduced in the form of compounds such as SiH ₄ and Si ₂ H ₆ or H ₂ , these compounds or H ₂ are decomposed by gas discharge and incorporated into the layer as the layer grows. In the present invention, the amount of H contained in the photoconductive layer is usually 1.0 to 40 atomic %, preferably 1.0 to 40 atomic %, in order that the formed image forming member can be sufficiently applied to practical applications. It is desirable that the content be 5 to 30 atomic%. Incorporation of H into the photoconductive layer composed of a-Si:H can be achieved by using, for example, a glow discharge method in which a hydrogen compound such as SiH ₄ or Si ₂ H ₆ is used as the starting material for forming a-Si:H. Therefore, when hydrogen compounds such as SiH ₄ and Si ₂ H ₆ are decomposed and a layer is formed, H is automatically contained in the layer. In this case, when forming the layer, H ₂ gas may be introduced into the apparatus system that performs glow discharge. When using the sputtering method, H ₂ gas is introduced when sputtering is performed using Si as a target in an atmosphere of an inert gas such as Ar or a mixed gas based on this gas, or
A silicon hydride gas such as SiH ₄ or Si ₂ H ₆ or a gas such as B ₂ H ₆ or PH ₃ which also serves as impurity doping may be introduced. a-Si:H can be controlled to the above-mentioned types by doping with impurities during manufacturing. In order to make a-Si:H p-type, suitable impurities to be doped into a-Si:H include elements of group A of the periodic table, such as B, Al, Ga, In, and Tl. In the case of n-type,
Elements of group A of the periodic table, such as N, P, As,
Preferred examples include Sb and Bi. The amount of impurity doped into a-Si:H is appropriately determined depending on the desired electrical and optical properties, but in the case of impurities in group A of the periodic table, it is usually 10 ^-6 ~ 10 ^-3 atomic%, preferably
10 ^-5 to 10 ^-4 atomic%, in the case of impurities of group A of the periodic table, usually 10 ^-8 to ^{10 -3} atomic%, preferably
It is desirable that it be 10 ^-8 to 10 ^-4 atomic%. The method of doping these impurities into a-Si:H differs depending on the manufacturing method adopted when forming the a-Si:H layer, and the details are explained below. Or it will be explained in detail in the examples. The thickness of the photoconductive layer is determined by the desired electrical
When applied to optical properties and electrophotography, it is determined appropriately depending on the electrophotographic properties and usage conditions, such as whether flexibility is required, but in normal cases 1 to 1. 80μ, preferably 3-70μ,
The optimum thickness is preferably 5 to 50μ. Hereinafter, the remarkable effects of the present invention will be explained according to Examples. Example 1 A cleaned 4 x 4 cm aluminum substrate was fixed to a substrate holder in a glow discharge deposition tank, the tank was made to have a vacuum of 5 x 10 ^-5 torr, and the substrate temperature was set to 230 °C.
It was kept at ℃. Next, silane gas was flowed into the tank at 30 ml per minute to maintain the internal pressure in the tank at 0.1-torr, and then 13.56 MHz RF power was applied between the electrodes to generate a glow discharge and a power of 30 W was generated. The matching circuit was adjusted so that . After continuing the discharge for 4 hours and forming a 5μ thick a-Si:H film, the discharge was stopped and the substrate was left in a vacuum in the deposition tank until the temperature dropped to below 60℃, and then exposed to the atmosphere. I took it out. The a-Si:H film thus obtained was fixed in a cryostat which was connected to a vacuum pump via a stop valve and also to a gas (O ₂ , NH _{3 ,} etc.) cylinder via a stop valve.
Desorption of the adsorbed gas was measured by heat treatment at 150° C. for 30 minutes while maintaining a vacuum of 2×10 ⁻³ torr inside the cryostat. Subsequently, after cooling to room temperature while maintaining the vacuum, the valve connected to the vacuum pump was closed, and then O ₂ gas was introduced to 1 atm and left for 1 hour. The a-Si:H film thus obtained was immediately
After being charged with a 6KV corona charger, 15 lux・
Image exposure was performed with an exposure amount of sec to form an electrostatic latent image, cascade development was performed with charged powder toner (200 μ iron powder carrier), and electrostatic transfer/heat fixation was performed, resulting in a high quality image. . Whereas with the combination of charged powder toner with 6KV corona charging,
Only images with low image density and sharpness that could not be used practically were obtained. Example 2 The a-Si film produced in the same manner as in Example 1 was taken out of the deposition tank and subjected to the same pretreatment in a cryostat, and then 1 atm of NH ₃ gas was introduced instead of O ₂ . -Si:H films were subjected to the same tests as in Example 1, and the results are shown in Table 1, including the case of Example 1.

[Table] Example 3 After forming a 5 μm a-Si:H film in the same manner as in Example 1, glow discharge was performed for another 10 minutes using silane gas mixed with 200 vol ppm of B ₂ H ₆ gas, and a p-type film was laminated. A film was prepared, subjected to the same treatment as in Examples 1 and 2, and tested. The results are shown in Table 2.

[Table] The procedure for image evaluation and creation of comparative examples is the same as in Example 2. Example 4 Instead of B ₂ H ₆ 200ppm laminated in Example 3
Table 3 shows the results of a similar test conducted on layers laminated using silane gas mixed with 100 ppm of PH ₃ .

[Table] The procedure for image evaluation and creation of comparative examples is the same as in Example 2. Example 5 Layer (A) used in Examples 1 and 2, Layer (B) used in Example 3, Layer (B) used in Example 4 For each layer prepared in the same manner as layer (C), in a cryostat.
After being treated under vacuum at 150℃ for 30 minutes, it was left to cool.
Immediately after leaking into the atmosphere, layers A, B, and C were immersed in a 5% parachloranil benzene solution, taken out immediately, and dried in a dryer at 80° C. for 2 hours. After that, the test results were shown in Table 4 after being left in the atmosphere for 6 hours.

[Table] Example 6 Membranes A, B, and C similar to those in Example 5 were immersed in a benzene solution of 5% diphenylamine instead of parachloranil, dried in the same manner, and then left to stand for testing. Table 5 shows the results. It was shown to.

【table】

Claims (1)

[Scope of Claims] 1. A photoconductive layer made of amorphous hydrogenated silicon containing hydrogen in an amount of 1 to 40 atomic % is formed on a support, and then on the surface of the photoconductive layer immediately after formation, A method for manufacturing an electrophotographic image forming member, characterized in that an adsorption layer is provided by contacting amorphous silicon hydride with either an electron-accepting molecule or an electron-donating molecule in gaseous or liquid form. . 2. The electrophotographic image forming member according to claim 1, wherein the surface of the photoconductive layer is subjected to deaeration treatment before providing the adsorption layer.