JP2011054638A - Method of manufacturing photoconductive layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a photoconductive layer capable of efficiently moving generated charges to an electrode. <P>SOLUTION: A method of manufacturing the photoconductive layer composed of inorganic semiconductor particles constituting a radiation imaging panel configured to record radiation image information in the form of an electrostatic latent image includes forming a coating film 3 by coating a temporary support 2 with a dispersion liquid 1 in which the inorganic semiconductor particles and a binder are dispersed, and pressing the coating film 3 after vacuum drying. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a photoconductive layer constituting a radiation imaging panel.

  Today, in X-ray (radiation) imaging for medical diagnosis and the like, an X-ray image information recording means is a radiation detector (having a semiconductor as a main part), and X is transmitted through the subject by the radiation detector. Various X-ray imaging apparatuses that detect lines and obtain an image signal representing an X-ray image related to a subject have been proposed and put into practical use.

  Various systems have also been proposed as radiation detectors used in this apparatus. For example, from the aspect of the charge generation process that converts X-rays into electric charges, the signal charge obtained by detecting the fluorescence emitted from the phosphor by the photoconductive layer when irradiated with X-rays is temporarily stored in the power storage unit. Then, the photoelectric charge (indirect conversion method) radiation detector that converts the stored charge into an image signal (electrical signal) and outputs it, or the signal charge generated in the photoconductive layer when irradiated with X-rays. There is a direct conversion type radiation detector that collects with a charge collecting electrode, temporarily accumulates in a power storage unit, converts the accumulated charge into an electric signal, and outputs the electric signal. The radiation detector in this direct conversion system has a radiation photoconductive layer and an electrode as main parts.

  On the other hand, from the aspect of the charge reading process for reading out the accumulated charge to the outside, a light reading method of reading light by irradiating a reading light (reading electromagnetic wave) to a detector, or a TFT (thin film transistor) connected to a power storage unit : Thin film transistor) and a TFT readout method of reading out by scanning.

As a method for producing a photoconductive layer used in the above-mentioned various types of radiation detectors at a lower cost, inorganic particles that cause radiation photoconduction are dispersed together with an organic solvent using a polymer as a binder, and this is applied and dried. For example, Patent Document 1 discloses an example in which an X-ray photoconductive layer is applied on a substrate with TFTs. Patent Document 2 describes a method for producing an X-ray photoconductive layer using HgI ₂ as a polymer and Patent Document 3 using PbO as a polyimide binder.

Japanese Patent Laid-Open No. 11-211832 US Patent Application Publication No. 2005/0118527 US Patent Application Publication No. 2007/0122543

  However, the radiation photoconductive layer formed by these coating methods has a problem that the charge generated in the radiation photoconductive layer hardly reaches the electrode because the binder functions as an insulator. In general, the surface of the inorganic semiconductor particles in the radiation photoconductive layer has a high potential, and there is a potential barrier even if the particles are physically joined to each other. Even when an electric field is applied due to this barrier, the charge generated in the inorganic semiconductor particles will die while reaching the electrode, or will be trapped, and the sensitivity (generated charge) will tend to be low. It is thought that there is.

  As a result of intensive studies by the present inventors, it is possible to efficiently transfer charges generated in the photoconductive layer to the electrode by making the process for producing the photoconductive layer different from the conventional one by the coating method. It has been found that a layer can be produced. The present invention has been made in view of such circumstances, and an object thereof is to provide a method for producing a photoconductive layer capable of efficiently transferring charges generated in the photoconductive layer to an electrode. .

The method for producing a photoconductive layer of the present invention is a method for producing a photoconductive layer comprising inorganic semiconductor particles constituting a radiation imaging panel for recording radiation image information as an electrostatic latent image, the inorganic semiconductor particles and a binder The dispersion is dispersed on a temporary support to form a coating film, the coating film is vacuum-dried, and then pressed.
The inorganic semiconductor particles are preferably Bi ₁₂ MO ₂₀ (wherein M is at least one of Si, Ge, and Ti) particles.
The press is preferably a hot press or a calendar.

  In the method for producing a photoconductive layer of the present invention, a dispersion liquid in which inorganic semiconductor particles and a binder are dispersed is applied onto a temporary support to form a coating film, and the formed coating film is vacuum dried and then pressed. The charge generated in the photoconductive layer can be efficiently transferred to the electrode. Although the detailed mechanism of action is not necessarily clear, by vacuum drying the coating film, it has some positive effects on the inorganic semiconductor fine particles, the press after vacuum drying reduces the voids in the radiation photoconductive layer, As a result of the good contact between the inorganic semiconductor particles, it is considered that this contributes to an improvement in the amount of generated charges.

It is a schematic diagram which shows the process of the manufacturing method of the photoconductive layer of this invention. It is a schematic cross-sectional schematic diagram of the manufacturing apparatus provided with the shear type stirrer used in the Example.

Below, the manufacturing method of the photoconductive layer of this invention is demonstrated with reference to drawings. FIG. 1 is a schematic diagram showing the steps of the method for producing a photoconductive layer of the present invention. First, a dispersion 1 in which inorganic semiconductor particles and a binder are dispersed is prepared (FIG. 1 (a)). As the inorganic semiconductor fine particles, those having a small atomic number and high density are preferable. For example, CdTe (density 5.9 g / cm ³ ), CdTe doped with Zn (CdZnTe, hereinafter also referred to as CZT), HgI ₂ (density 6.4 g / cm ³ ), PbI ₂ (density 6.2 g / cm ³ ), PbO (density 9.8 g / cm ³ ), Bi ₁₂ MO ₂₀ (M is at least in Si, Ge, Ti) Inorganic semiconductor fine particles having a high atomic number and a high density of main elements such as BiI ₃ can be used. Among them, Bi ₁₂ MO ₂₀ is preferable because of its high stability and high radiation absorption.

  Preferred examples of the binder include acrylic organic resins, polyimides, BCB (benzodiclobutene), PVA (polyvinyl alcohol), polyethylene, polycarbonate, and polyetherimide. In particular, acrylic organic resin and polycarbonate are preferable, and polycarbonate is particularly preferable. The volume ratio of the inorganic semiconductor particles to the binder depends on the type of the binder and the inorganic semiconductor particles, the type of solvent described later, the temperature and time of vacuum drying, etc., but is preferably 85% or less, and 80% or less. It is more preferable.

  For the dispersion, a solvent can be used for preparing the dispersion, for example, alcohols such as methanol, ethanol, propanol, and butanol, chlorine-containing hydrocarbons such as methylene chloride, ethylene chloride, chlorobenzene, and dichlorobenzene, acetone, methyl ethyl ketone, Preferred examples include ketones such as methyl isobutyl ketone, esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate, and butyl acetate, dioxane, ethylene glycol monoethyl ether, ethers such as ethylene glycol monomethyl ether, toluene, and the like. The above solvents can be used alone or in appropriate mixture.

  Next, the dispersion 1 is flowed on the temporary support 2 (FIG. 1 (b)). As a temporary support, for example, various materials used as a support for an intensifying screen (or intensifying screen) in conventional radiography, or as a support for a radiation image conversion panel It can be arbitrarily selected from known materials used. Specifically, plastic materials such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil and aluminum alloy foil, ordinary paper, baryta paper, resin coated paper, dioxide dioxide Examples thereof include pigment papers containing pigments such as titanium, papers sized with polyvinyl alcohol, ceramic plates or sheets such as alumina, zirconia, magnesia, and titania.

As will be described later, a dispersion is applied on the temporary support, vacuum-dried, and then peeled off from the temporary support to form a coating film. Therefore, a release agent is applied to the surface of the temporary support in advance. It is preferable that the formed coating film is easily peeled off. The release agent coating film can be formed, for example, by applying a solution obtained by dissolving dimethyl silicone in toluene onto a temporary support using a spin coater or a doctor blade, and drying.
Subsequently, as shown in FIG. 1 (c), the dispersion liquid on the temporary support is formed into a coating film 3 by a coating method such as a known dip method, spray coating method, bar coater coating method, or Giesser coating method.

  After forming the coating film 3, it is vacuum-dried (FIG. 1 (d)). The ultimate vacuum in vacuum drying is preferably 1500 Pa or less, and more preferably 1000 Pa or less. If the pressure is higher than 1500 Pa, it is not preferable because the inorganic semiconductor fine particles cannot be affected in any way. The vacuum drying time is preferably a time for completely evaporating the solvent, and the vacuum drying temperature can be arbitrarily selected within the range of room temperature to the boiling point of the solvent.

Next, pressing is performed on the vacuum-dried coating film 3 ′. The pressing may be performed immediately after the vacuum drying, or may be performed after being left for several days. The pressing can be performed by hot pressing (FIG. 1 (e)) or calendar (FIG. 1 (f)). Across the hot pressing coating film 3 'between the opposing metal plate 4, a method of pressing over temperature, the pressing pressure is preferably 200~2000kg / cm ^2, more preferably 300~1500kg / cm ² . The pressing temperature is preferably 10 ° C. to 200 ° C., more preferably 20 ° C. to 180 ° C., although it depends on the pressing pressure and pressing time. The pressing time depends on the pressing pressure and pressing temperature, but is preferably 10 seconds to 1 hour, and more preferably 30 seconds to 30 minutes.

  The calendar is a method of pressing the coating film 3 ′ by sandwiching the coating film 3 ′ between the films 5 (for example, PET) and passing between the two rolls 6, and the pressing force is applied to the coating film 3 ′. Depending on the speed at which the film passes between the rolls 6, 50 to 500 kg / cm is preferable, and 75 to 375 kg / cm is more preferable. The pressing speed depends on the pressing force, but is preferably 0.01 to 10 m / min, and more preferably 0.02 to 5 m / min.

  If the pressing pressure in the pressing step is too small, voids in the radiation photoconductive layer are not reduced, and contact between the inorganic semiconductor particles is unfavorable. On the other hand, if the pressing pressure is too high, the inorganic semiconductor particles are broken, which is not preferable.

  The photoconductive layer produced by the production method of the present invention can be applied to a direct conversion radiation imaging panel that directly converts radiation into electric charge and accumulates electric charge. It can be used for alpha rays. In addition, the photoconductive layer manufactured by the manufacturing method of the present invention accumulates charges generated by radiation irradiation, and turns on the accumulated charges one pixel at a time for an electrical switch such as a thin film transistor (TFT). It can be used for a method of reading by turning off (hereinafter referred to as a TFT method) or a so-called optical reading method of reading by a radiation image detector using a semiconductor material that generates a charge by light irradiation.

Examples of the former TFT type radiation imaging panel include those described in JP-A-2006-96557, [0067] to [0073]. The radiation photoconductive layer 104 of the radiation imaging panel shown in FIG. In addition, the photoconductive layer produced by the production method of the present invention can be used. Moreover, as a radiation imaging panel used for the latter optical reading system, for example, those described in [0051] to [0066] of Japanese Patent Application Laid-Open No. 2006-96557 can be cited, and the radiation imaging panel shown in FIG. A photoconductive layer manufactured by the manufacturing method of the present invention can be used for the recording radiation conductive layer 2.
The Example of the manufacturing method of the photoconductive layer of this invention is shown below.

(Preparation of Bi ₁₂ SiO ₂₀ particles)
482 g of bismuth nitrate pentahydrate (Bi (NO ₃ ) ₃ .5H ₂ O: purity 99.9%) was dissolved in 800 ml of 1N aqueous nitric acid solution, and water was added thereto to prepare 1000 ml of additive solution a. Separately, 12.9 g of potassium metasilicate and 325 g of potassium hydroxide were dissolved in water to make 1000 ml, and an additive solution b was prepared. On the other hand, 7.7 g of potassium metasilicate and 281 g of potassium hydroxide were dissolved in water to make 5000 ml to prepare a mother liquor.

Bi ₁₂ SiO ₂₀ particles were produced using a production apparatus 21 equipped with a shear type stirrer shown in FIG. The manufacturing apparatus 21 shown in FIG. 2 includes a reaction vessel 22 for performing a reaction by stirring and mixing an alkaline solution and a bismuth compound solution, a jacket 23 for heating and keeping the reaction vessel 22, a solution vessel 24 into which an alkaline solution is injected, bismuth A solution feeding path 26 and 27 for feeding the alkaline solution and the bismuth compound solution from each of the solution bottle 25, the solution bottles 4 and 5 into which the compound solution is injected to the reaction tank 22, and a shear for stirring the solution in the reaction tank 22 This is a device comprising a mold stirrer 28 and a motor 29 for driving the shear stirrer 28.

The mother liquor prepared above was injected into the reaction vessel 22 of the production apparatus 21, and the additive solution a was injected into the solution supply vessel 24 and the additive solution b was injected into the solution supply vessel 25. The mother liquor was heated by the jacket 23 so that the temperature of the mother liquor was 90 ° C. The mother liquor was agitated by the shear type agitator 28 with the rotation speed of the motor 29 set to 4000 revolutions per minute. At this time, the peripheral speed of the stirring blade was 3.5 m / sec. While maintaining this state, the additive solution a from the solution feeder 24 and the additive solution b from the solution feeder 25 were each added to the reaction vessel 22 at a rate of 20 ml per minute. After completion of the addition, the mixture was further stirred for 30 minutes, and then cooled to room temperature, and the resulting pale yellow dispersion was filtered. After filtration, it was washed three times with a 0.1N potassium hydroxide solution and several times with water, and then washed with ethanol to obtain Bi ₁₂ SiO ₂₀ particles.

Example 1
The Bi ₁₂ SiO ₂₀ powder prepared above was mixed with a chlorobenzene solution of polycarbonate containing 6.4% of polycarbonate. The obtained mixture was uniform, and the volume ratio occupied by Bi ₁₂ SiO ₂₀ powder in the mixture of Bi ₁₂ SiO ₂₀ powder and polycarbonate was 80%. A Bi ₁₂ SiO ₂₀ powder-polycarbonate-chlorobenzene mixed solution was applied to a PET release base, and the coating film was vacuum-dried. The ultimate vacuum was 1000 Pa. The time for chlorobenzene to evaporate and dry completely was 20 minutes. After drying, Bi ₁₂ SiO ₂₀ powder - peeling off the polycarbonate mixture release base. A part of the Bi ₁₂ SiO ₂₀ powder-polycarbonate mixture was cut out and the amount of residual solvent was measured to be 0.497% by mass (the residual solvent amount was dried at 200 ° C. for 12 hours, and the weight before and after drying). Determined by dividing the decrease by the mass before drying).

The Bi ₁₂ SiO ₂₀ powder-polycarbonate mixture was hot pressed at 60 ° C. and 900 kg / cm ² . A 6 μm PET film was laminated on both sides of the mixture after pressing to form an X-ray photoconductive layer. The detection part of the X-ray imaging panel was completed by joining two Ti / Au electrodes produced by vapor deposition on a quartz glass substrate with the X-ray photoconductive layer sandwiched therebetween.

(Example 2)
The detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that hot pressing was performed at 60 ° C. and 300 kg / cm ² .

(Example 3)
The detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that hot pressing was performed at 60 ° C. and 600 kg / cm ² .

Example 4
The detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that hot pressing was performed at 60 ° C. and 1200 kg / cm ² .

(Example 5)
The detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that hot pressing was performed at 60 ° C. and 1700 kg / cm ² .

(Example 6)
In Example 1, the detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that instead of hot pressing, pressing was performed at 60 ° C. and 100 kg / cm with a calendar device.

(Example 7)
In Example 1, the detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that the ultimate vacuum for vacuum drying was 1200 Pa.

(Example 8)
In Example 1, the detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that the ultimate vacuum for vacuum drying was set to 800 Pa.

(Comparative Example 1)
In Example 1, the coating film of the Bi ₁₂ SiO ₂₀ powder-polycarbonate-chlorobenzene mixed solution was dried at atmospheric pressure at room temperature instead of vacuum drying. The time for chlorobenzene to evaporate and dry completely was 1 hour, and the amount of residual solvent was 0.502% by mass. The detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 without hot pressing the dried coating film.

(Comparative Example 2)
The detection unit of the X-ray imaging panel was completed in the same manner as in Example 1, except that the coating film of the Bi ₁₂ SiO ₂₀ powder-polycarbonate-chlorobenzene mixed solution was dried at atmospheric pressure at room temperature instead of vacuum drying. I let you.

(Comparative Example 3)
In Example 1, the detection unit of the X-ray imaging panel was completed in the same manner as in Example 1 except that hot pressing was not performed on the dried coating film.

(Comparative Example 4)
In Example 1, the detection part of the X-ray imaging panel was set in the same manner as in Example 1 except that the coating film of the Bi ₁₂ SiO ₂₀ powder-polycarbonate-chlorobenzene mixed solution was dried at atmospheric pressure at 60 ° C. instead of vacuum drying. Completed. The chlorobenzene evaporated by this drying, and the drying time was 20 minutes, and the residual solvent amount was 0.483% by mass.

(Evaluation)
After a voltage of 3000 V was applied between the electrodes of the X-ray imaging panel detection unit produced in the above examples and comparative examples, X-rays equivalent to 1 mR (tungsten ball, 70 kV pressure) were exposed for 0.1 seconds. At this time, the photocurrent flowing between the electrodes was converted into a voltage by a current amplifier and measured with a digital oscilloscope. From the obtained current / time curve, integration was performed in the range of the X-ray irradiation time, and the amount of generated charges per area of the X-ray photoconductive layer was converted. The evaluation results are shown in Table 1 together with the volume ratio of particles, drying conditions, residual solvent amount, and pressing conditions. The generated charge amount is shown as a relative value with the generated charge amount of Comparative Example 1 as 100.

In addition, about the sheet | seat (X-ray photoconductive layer) of the state which has not attached the electrode of Examples 1-6 and Comparative Examples 1-4, while calculating the volume from the area and film thickness, the weight of each sheet | seat was measured. The binder weight value calculated from the charging ratio was subtracted, and the density (g / cm ³ ) was calculated from the obtained volume and weight. From the bulk density of Bi ₁₂ SiO ₂₀ , 9.14 (g / cm ³ ), the packing factor (sample density / 9.14) was calculated. The film thickness of each sample was 200 to 600 μm.

  As shown in Table 1, the amount of residual solvent was almost the same as 0.497% by mass in vacuum-dried Examples 1 to 6 and 0.502% by mass in Comparative Examples 1 and 2 dried at room temperature in the atmosphere. However, there was a significant difference in the amount of generated charge. In particular, Example 1 and Comparative Example 2 were the same in pressing conditions but differed only in drying conditions, but the amount of generated charges in Example 1 was more than three times that in Comparative Example 2. The amount of charge generated by coating is considered to be determined by the difference in the filling rate of the inorganic semiconductor fine particles, but Example 1 and Comparative Example 2 have no significant difference in the filling rate. Further, when Examples 1, 7, and 8 are compared, the sensitivity is higher as the ultimate vacuum in vacuum drying is lower. From this, it is considered that vacuum drying does not affect the amount of residual solvent but rather contributes to the improvement of the amount of generated charges as a result of some positive effect on the inorganic semiconductor fine particles. In Example 6, pressure was applied by calendering, but the amount of generated charge was similarly improved in calendering.

Further, as the hot press pressure is increased, the amount of generated charges also increases. However, in Examples 1 to 5, the generated charge amount is the highest in Example 1 where the pressure is 900 kg / cm ^2. In Example 4 which is 1200 kg / cm ² and Example 5 where the pressure is 1700 kg / cm ² , the generated charge amount was lower than that in Example 1. This is considered to be because the inorganic semiconductor fine particles in the coating film are destroyed when the pressure becomes too high.

(Preparation of Bi ₁₂ GeO ₂₀ particles)
Bismuth oxide (Bi ₂ O ₃ ) powder and germanium oxide (GeO ₂ ) powder were blended at a molar ratio of 6: 1, and ball mill mixing was performed in ethanol using zirconium oxide balls. This was recovered and dried, and then calcined at 800 ° C. for 8 hours to obtain Bi ₁₂ GeO ₂₀ powder by a solid phase reaction between bismuth oxide and germanium oxide. This Bi ₁₂ GeO ₂₀ powder was coarsely pulverized in a mortar to reduce the particle size to 150 μm or less, and then pulverized and dispersed in ethanol using a zirconium oxide ball in ethanol. The dried product was used as Bi ₁₂ GeO ₂₀ powder.

(Example 11)
In Example 1, a radiation detector was completed in the same manner as in Example 1 except that the Bi ₁₂ GeO ₂₀ particles prepared above were used instead of Bi ₁₂ SiO ₂₀ particles.

(Example 12)
The detection unit of the X-ray imaging panel was completed in the same manner as in Example 11 except that instead of hot pressing in Example 11, pressing was performed at 60 ° C. and 100 kg / cm with a calendar device.

(Comparative Example 11)
A radiation detector was completed in the same manner as in Comparative Example 1 except that the Bi ₁₂ GeO ₂₀ particles produced above were used instead of Bi ₁₂ SiO ₂₀ particles in Comparative Example 1.

(Measurement of generated charge)
With respect to the detection units of the X-ray imaging panels produced in Examples 11 and 12 and Comparative Example 11, the amount of generated charges was determined by the same method as described above. The results are shown in Table 2. The generated charge amount is shown as a relative value with the generated charge amount of Comparative Example 11 as 100.

As shown in Table 2, even in the X-ray imaging panel manufactured using Bi ₁₂ GeO ₂₀ particles, the amount of residual solvent in Example 11 was the same as that of the X-ray imaging panel manufactured using Bi ₁₂ SiO ₂₀ particles. Although it was almost the same as 0.402 mass% and 0.502 mass% in the comparative example 11 which dried at room temperature in air | atmosphere, it became a big significant difference in the amount of generated charges.

(Example 21)
Instead a Bi ₁₂ SiO ₂₀ powder in Example 1, the mixing ratio when mixing the chlorobenzene solution of polycarbonate containing polycarbonate 6.4%, Bi ₁₂ SiO in a mixture of Bi ₁₂ SiO ₂₀ powder and polycarbonate _A radiation detector was completed in the same manner as in Example 1 except that the volume ratio of ₂₀ powder was 88%.

(Example 22)
The radiation detector was changed in the same manner as in Example 21 except that the volume ratio occupied by Bi ₁₂ SiO ₂₀ in the mixture of Bi ₁₂ SiO ₂₀ powder and polycarbonate was 85%. Was completed.

(Example 23)
The radiation detector was changed in the same manner as in Example 21 except that the volume ratio occupied by Bi ₁₂ SiO ₂₀ in the mixture of Bi ₁₂ SiO ₂₀ powder and polycarbonate was 79%. Was completed.

(Example 24)
The radiation detector was changed in the same manner as in Example 21 except that the volume ratio occupied by Bi ₁₂ SiO ₂₀ in the mixture of Bi ₁₂ SiO ₂₀ powder and polycarbonate was changed to 72%. Was completed.

(Example 25)
The radiation detector was changed in the same manner as in Example 21 except that the volume ratio occupied by Bi ₁₂ SiO ₂₀ in the mixture of Bi ₁₂ SiO ₂₀ powder and polycarbonate was 56%. Was completed.

(Measurement of generated charge)
About the detection part of the X-ray imaging panel produced in Examples 21-25, the generated charge amount was calculated | required by the method similar to the above. The results are shown in Table 3. The generated charge amount is shown as a relative value with the generated charge amount of Example 21 as 100.

  Conventionally, it has been considered that the amount of charge generated in the photoconductive layer by coating can be improved by increasing the filling rate of the inorganic semiconductor fine particles. To increase the filling rate, the proportion of the inorganic semiconductor fine particles in the coating solution can be increased. However, as shown in Table 3, in Example 25 where the proportion of inorganic semiconductor fine particles was 56% and Example 23 where 79% was inorganic semiconductor fine particles increased by 20% or more. In Example 21, in which the amount of generated charges did not increase by 8% and the ratio of inorganic semiconductor fine particles was 88%, conversely, the amount of generated semiconductor particles was 1/3 of the generated charge amount of Example 25 in which the ratio of inorganic semiconductor fine particles was 56%. Was not satisfied. From this, it can be seen that in order to increase the amount of generated charge, the interval between the inorganic semiconductor fine particles is important, and it is important to apply pressure.

In this example, the inorganic semiconductor fine particles using BMO are exemplified, but other main elements such as CdTe, CZT, HgI ₂ , PbI ₂ , PbO, BiI ₃ have a high atomic number, and the density High inorganic semiconductor fine particles can be used. These inorganic semiconductor fine particles are almost the same in that the atomic number of the element is small and the density is high, and it is assumed that the same result can be obtained.

DESCRIPTION OF SYMBOLS 1 Dispersion liquid 2 Temporary support body 3,3 'Coating film

Claims (3)

  A method for producing a photoconductive layer comprising inorganic semiconductor particles constituting a radiation imaging panel for recording radiation image information as an electrostatic latent image, wherein a dispersion liquid in which the inorganic semiconductor particles and a binder are dispersed is placed on a temporary support. A method for producing a photoconductive layer, comprising: forming a coating film by coating, vacuum drying the coating film, and pressing the coating film. Wherein the inorganic semiconductor particles Bi ₁₂ MO ₂₀ (although, M is Si, Ge, at least one of Ti) The process according to claim 1, the photoconductive layer according to characterized in that the particles.   The method for producing a photoconductive layer according to claim 1, wherein the press is a hot press or a calendar.

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