JP3821883B2 - Method for producing amorphous tin oxide sol - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing an amorphous oxide Suzuzo Le.
[0002]
[Prior art]
In general, tin oxide is a semiconductor and does not exhibit high conductivity by itself, but it is known that high conductivity can be obtained by doping different atoms. Moreover, it is a material excellent in transparency and physical and chemical stability, and is expected to be used for electrical and electronic applications.
[0003]
Such tin oxide is famous for its transparent conductive oxide film composed of a combination of antimony and indium, and has many uses. However, high-purity tin oxide or amorphous tin oxide has low conductivity, so Not considered.
[0004]
For these materials, as described in Research Report No. 35 “Study on Tin Oxide” published by the Science and Technology Agency published by the Science and Technology Agency, it has high conductivity except for doping or compounding of certain metal compounds. Does not show sex. When the purity is increased, a semiconductor region is formed, and the conductivity reaches 10 ⁶ Ωcm or more. Therefore, many efforts have been made to increase conductivity in order to use the transparent conductive material in applications.
[0005]
The transparent conductive material is generally used by being coated on a substrate by a film forming method such as chemical vapor deposition, vacuum vapor deposition, reactive ion plating, sputtering, or ion beam sputtering.
[0006]
However, these methods have disadvantages that not only the apparatus is expensive, complicated and large, but also the film formation rate is low and a film having a large area cannot be obtained. Further, when forming a film having a complicated shape, it tends to be non-uniform and there are many restrictions on use.
[0007]
On the other hand, a method of dipping a liquid raw material on a substrate, a method of applying by spraying, a method of applying using an air doctor, a bar coater, etc. can obtain a film of a large area relatively easily. In addition, the method can be applied relatively easily to a part having a complicated shape, and is an industrially promising method. Such a coating method has been widely studied also for tin oxide-based materials.
[0008]
The tin oxide-based material that has been studied conventionally is a salt solution of an organic or inorganic compound mainly containing both tin and antimony as ions. Therefore, when using a salt solution of an organic compound, it must be carefully pyrolyzed so that no organic matter remains, and tin and antimony are scattered as an organic salt, and the polarity of the solution is low and a substrate such as glass is used. A uniform film could not be obtained.
[0009]
In addition, as a result of requiring a large amount of stabilizing material to maintain the liquid stability of the organic salt, only a thin film thickness can be obtained, and because of the high organic matter content, even if multi-layer dipping is performed after drying, it is peeled off during firing. There was a problem such as.
[0010]
Furthermore, tin oxide / antimony produced during pyrolysis generally has a coarse particle size, and there has been a problem in application to fields requiring uniform fineness. As a technique for solving such a problem, JP-A-62-223019 and JP-A-62-278705 disclose a method using a crystalline tin oxide sol produced by devising a production method.
[0011]
However, with these technologies, the sol solution is colored, the surface is not smooth when coated with sol because it is crystalline, and high conductivity is not exhibited unless it is fired once. Had a point.
[0012]
[Problems to be solved by the invention]
Therefore object of the present invention, coloration without conductivity is to provide a method for producing an amorphous oxide Suzuzo Le suitable for use in the transparent conductive material is good.
[0013]
[Means for Solving the Problems]
The present invention for solving the above problems has the following configuration.
1. A method for producing an amorphous tin oxide sol as shown below, after hydrolyzing a hydrolyzable tin compound and washing, the obtained halogen concentration of 0.001% to 3% is dissolved in ammonia water. A method for producing an amorphous tin oxide sol, wherein the heat treatment is carried out below the boiling point of water .
[Amorphous tin oxide sol]
An amorphous tin oxide sol having a long-range order in the atomic arrangement and a temperature range showing a change in the substance below the melting point (1127 ° C.) of crystalline tin oxide, and having a conductivity of less than 10 ⁵ Ωcm An amorphous tin oxide sol comprising crystalline tin oxide particles.
[0014]
2. A method for producing an amorphous tin oxide sol as shown below, wherein the halogen concentration obtained is hydrolyzed using a hydrolyzable tin compound and a fluorine-containing compound, and the resulting halogen concentration is 0.001% or more and 3% or less. A method for producing an amorphous tin oxide sol, wherein the raw material is dissolved in ammonia water and subjected to heat treatment at a temperature equal to or lower than the boiling point of water .
[Amorphous tin oxide sol]
An amorphous tin oxide sol having a long-range order in the atomic arrangement and a temperature range showing a change in the substance below the melting point (1127 ° C.) of crystalline tin oxide, and having a conductivity of less than 10 ⁵ Ωcm An amorphous tin oxide sol comprising crystalline tin oxide particles.
[0015]
3. 3. The amorphous oxide according to 1 or 2 above, wherein the amorphous tin oxide sol contains tin oxide that causes a weight loss of 0.1 wt% or more and less than 30 wt% in the range of 200 ° C. to 500 ° C. by heat treatment. Manufacturing method of tin sol.
[0016]
4). 3. The method for producing an amorphous tin oxide sol according to 1 or 2, wherein the amorphous tin oxide sol contains tin oxide containing at least 0.001 wt% or more of anions.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below.
First, in the present invention, amorphous means a substance different from crystalline. Crystalline refers to a long-range order in the atomic arrangement, as described in page 4 of the University of Electrical and Electronics Engineering Vol. 72, Evaluation of Crystals (Jun Ito, Nao Inuzuka, Corona, 1982). The substance is characterized by having a solid-phase melting point. For example, a highly pure, colorless and transparent crystalline tin oxide has a tetragonal rutile structure, a refractive index of 1.9968, and an electrical conductivity of 10 ⁶ Ωcm or higher at room temperature. It has been. The melting point is 1127 ° C., and crystalline tin oxide is thermally stable up to this temperature. Therefore, in general, amorphous tin oxide is a substance that does not exhibit the above properties,
(1) There is no long-range order in the atomic arrangement,
(2) There is a temperature range showing the change of the substance below the melting point of crystalline tin oxide.
It can be said that it is tin oxide.
[0019]
Regarding (1), it is possible to identify the structure by X-ray diffraction, and it is long from the measurement of crystallite size described in the new edition of Karity X-ray diffraction theory (translated by Gentaro Matsumura, Agne, 1977). You can know the approximate value of the distance order. For example, the spacing between the (110) planes of tin oxide is approximately 0.33 nm. For crystalline tin oxide, there must be several tens or more of repeating units. A value is observed. Therefore, if the crystallite measurement is less than 10 nm, it can no longer be said that there is long-range order, and it seems amorphous. If it is less than 5 nm, the number of repeating units is no longer 10 and it is not a crystal.
[0020]
Regarding (2), it will be readily apparent if thermal analysis of a solid is performed, and even if the influence of measurement conditions and the influence of sample size are taken into consideration, it is difficult to say that it is a crystal if a thermal change occurs below 1000 ° C. Thermogravimetric analysis can be easily observed with a thermal change. If weight at 200 ° C. is used as a measurement starting weight and a weight loss is 0.1 wt% or more in a temperature range of up to 500 ° C., which is much lower than the melting point. It is not single crystal tin oxide.
As described above, in the case of tin oxide satisfying the above (1) or (2), it is clearly amorphous.
[0021]
Next, the term “conductivity” means the conductivity of the tin oxide particles, and the measurement method may be any method as long as the conductivity can be accurately evaluated. Although a measurement example is shown below, the present invention is not limited.
[0022]
A tin oxide thin film is formed on a quartz plate and processed in air at 200 ° C. After measuring the thickness of the thin film at room temperature of 25 ° C., the resistance is measured by the four-terminal method, and the volume resistivity is obtained from the resistance value and the film thickness. A sol containing tin oxide particles having a volume resistivity of 10 ⁻² Ωcm or more and less than 10 ⁵ Ωcm determined by such a method is the tin oxide sol of the present invention.
[0023]
About the weight loss by heat processing, the value measured by the thermogravimetric analysis generally used is meant. The temperature rising rate is preferably 30 ° C./min or less, more preferably 10 ° C./min or less, and a sol containing tin oxide that produces a weight loss of 0.1 wt% to less than 30 wt% in the range of 200 ° C. to 500 ° C. is there.
[0024]
When the sol of the present invention is heated to 200 ° C. in air or in a non-oxidizing atmosphere such as N ₂ or Ar, amorphous tin oxide is obtained. If it is crystalline tin oxide, it is not accompanied by a thermal change by the process of 200 degreeC or more performed subsequently. Amorphous tin oxide shows a weight loss of 0.1 wt% or more. Although the relationship between the weight reduction amount and the conductivity is not clear, the present inventors have found that the tin oxide particles exhibiting the weight reduction have conductivity, and have reached the present invention.
[0025]
As for impurity ions, good results are obtained when cations such as ammonium ions and hydrogen ions and the following anions are present.
[0026]
The presence of anions is not particularly defined, but organic ions and inorganic ions are more conductive when they are present. Particularly preferred are carboxylic acid group or sulfonic acid group, amino group, ion containing hydroxyl group, carbonate ion and halogen ion. These ions may be present inside the amorphous tin oxide particles, or may be present outside or both inside and outside. However, as for the amount present, it is not preferable for the outside such as the surface to be present in an amount of 30 wt% or more with respect to the particles because it causes a problem in the stability of the sol, preferably less than 30 wt%, more preferably less than 10 wt%, particularly Preferably, less than 6 wt% is selected because of its good stability when made into a sol. The amount of anion present inside the particle is not specified because it does not affect the stability of the sol, but it is preferably 0.001 wt% or more and less than 6 wt%.
[0027]
As a manufacturing method of these tin oxide sols,
The method shown in claim 1, that is, after hydrolyzing the hydrolyzable tin compound and washing, the obtained raw material having a halogen concentration of 0.001% to 3% is dissolved in ammonia water so that the boiling point is below the boiling point of water. A method of performing heat treatment,
The method shown in claim 2, that is, after hydrolyzing and washing using a hydrolyzable tin compound and a fluorine-containing compound, the obtained raw material having a halogen concentration of 0.001% to 3% in ammonia water. A method of dissolving and heating at a boiling point of water or lower ,
Either method may be used.
[0028]
In the production method of the present invention, the temperature condition applied to the compound containing Sn is important in the whole production process, and a method involving high-temperature heat treatment is preferable because it causes the growth of primary particles and the phenomenon that the crystallinity increases. When heat treatment is required, the temperature is set to 450 ° C. or lower, particularly 300 ° C. or lower, preferably 200 ° C. or lower, more preferably 150 ° C. or lower. However, heating from 25 ° C. to 150 ° C. is a preferred means to be selected.
[0029]
Moreover, a manufacturing process consists of three processes, the process of hydrolyzing a hydrolysable tin compound, and the process of solating through the washing | cleaning process of the obtained deposit. The present invention does not place a restriction on each step being further subdivided. For example, the hydrolysis process is composed of a process of measuring and charging raw materials, a mixing process with components added for hydrolysis, a heating process, etc. This is not limited. The washing step involves a solid-liquid separation step, and any method such as decantation or ultrafiltration may be used.
The same applies to sol formation, and additives, solvents, and the like that are added to stably disperse the particles are not limited, but stabilization of the sol with aqueous ammonia is preferable from the viewpoint of economy.
[0030]
The compounds used in the production method shown in claim 1 are described below.
The hydrolyzable tin compound is a compound containing an oxo anion such as K ₂ SnO ₃ .3H ₂ O, a water-soluble halide such as SnCl ₄ , SnCl ₄ .5H ₂ O, R ′ ₂ SnR ₂ , R ₃ SnX, R ₂ SnX ₂ [R ′ represents an aliphatic or aromatic organic compound, R represents an aliphatic or aromatic organic compound, and X represents a halogen. ], For example, organometallic compounds such as (CH ₃ ) ₃ SnCl · (pyridine), (C ₄ H ₉ ) ₂ Sn (O ₂ CC ₂ H ₅ ) ₂ , Sn (SO ₄ ) ₂ · 2H An oxo salt such as ₂ O can be mentioned.
[0031]
In the method of producing from a decomposition reaction of a hydrolyzable tin compound in a solvent, it is possible to add a compound containing an element other than Sn that is soluble in the solvent during the process. For example, addition of a fluorine-containing compound that is soluble in a solvent or addition of a carbonate. The soluble fluorine-containing compound in a solvent may be any of ionic fluoride or covalent fluoride, for example, HF or _{KHF 2,} SbF 3, MoF ₆ and metal _fluoride, NH _{4 MnF 3,} NH 4 Examples include compounds that produce a fluoro complex anion such as BiF ₄ , inorganic molecular fluorides such as BrF ₃ , SF ₄ , and SF ₆ , and organic fluorine compounds such as CF ₃ I, CF ₃ OOH, and P (CF ₃ ) _3. However, when the solvent is water, a combination of a fluorine-containing compound and a non-volatile acid, such as a combination of CaF ₂ and sulfuric acid, can also be used.
[0032]
In the above manufacturing method, a cleaning process may be used in the middle. By using a cleaning process, it is possible to control the amount of ions contained in the sol. Although the washing | cleaning method is not specifically limited, For example, the method by a decantation, the method by an ultrafiltration membrane, etc. are mentioned.
[0033]
【Example】
Examples of the present invention will be described below.
Example 1
A homogeneous solution was obtained by dissolving 45 g of stannic chloride in 2000 ml of 30 ° C. water containing carbon dioxide. This was then boiled for 2 hours to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 10 times. Add 1000 ml of distilled water to make the total volume 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution.
The quartz plate is dipped into this sol solution and dried. This operation was repeated 100 times to form a tin oxide thin film on the quartz plate. When the volume resistivity of the sample obtained by treating this quartz plate in air at 150 ° C. for 2 hours was measured by the four probe method, it was 7 × 10 ⁴ Ωcm.
The sol solution was dried using a spray drying apparatus, and the powder was taken out from the sol solution. When the crystallite measurement of (100) plane was performed by powder X-ray diffraction using this powder, it was calculated | required as 2.1 nm, and it confirmed that it was an amorphous powder. Further, when thermogravimetric analysis of this powder was performed at a temperature rising rate of 10 ° C./min, it showed 1.0 wt% of the weight decrease gradually to 200 ° C., and then 2.5 wt% from 200 ° C. to 500 ° C. It showed a weight loss.
[0034]
Comparative Example 1
65 g of stannic chloride hydrate was dissolved in 2000 ml of distilled water at 100 ° C. to obtain a uniform solution. This was then boiled to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 40 times. Silver nitrate is dropped into distilled water from which the precipitate has been washed, and after confirming that there is no reaction of chlorine ions, 1000 ml of distilled water is added to make the total amount 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colloidal gel dispersion. The resulting sol solution was colorless and transparent.
After forming a thin film on the quartz plate by the same method as in Example 1, the volume resistivity was measured by the four-terminal method and found to be 2.1 × 10 ⁵ Ωcm.
Moreover, when crystallite measurement was performed, it was measured to be 3.1 nm.
[0035]
Comparative Example 2
65 g of stannic chloride hydrate was dissolved in 2000 ml of distilled water at 30 ° C. to obtain a uniform solution. This was then boiled to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 40 times. After washing with water, it was sprayed into a cylindrical electric furnace at 800 ° C. to take out the powder. This powder was dispersed in 2000 ml of water, 40 ml of 30% aqueous ammonia was added, and heated to 100 ° C. in a water bath to obtain a colloidal gel dispersion. The resulting sol solution was slightly cloudy.
After forming a thin film on a quartz plate by the same method as in Example 1, the volume resistivity was measured by a four-terminal method, which was 7.1 × 10 ⁶ Ωcm.
Moreover, when crystallite measurement was performed, it was measured to be 30.5 nm.
[0036]
As described above, it is clear from Example 1 and Comparative Examples 1 and 2 that the volume resistivity of tin oxide obtained by a slight difference in manufacturing conditions is different.
[0037]
Example 2
A uniform solution was obtained by dissolving 45 g of stannic chloride in 2000 ml of distilled water at 50 ° C. This was then boiled for 2 hours to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 8 times. Add 1000 ml of distilled water to make the total volume 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution.
When the chloride ion concentration contained in the sol solution was determined using ion chromatography, 0.008 wt% chloride ion was contained.
A thin film was formed using this sol solution on a quartz plate in the same manner as in Example 1, and the volume resistivity after heat treatment was determined to be 9.5 × 10 ⁴ Ωcm.
Moreover, it was 2.7 nm when the crystallite measurement was performed similarly to Example 1. FIG.
[0038]
Example 3
A homogeneous solution was obtained by dissolving 45 g of stannic chloride in 2000 ml of distilled water at 40 ° C. This was then boiled for 2 hours to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water seven times. Add 1000 ml of distilled water to make the total volume 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution.
When the concentration of chlorine ions contained in the sol solution was determined using ion chromatography, 0.016 wt% chlorine ions were contained.
A thin film was formed using this sol solution on a quartz plate in the same manner as in Example 1, and the volume resistivity after heat treatment was determined to be 9.5 × 10 ⁴ Ωcm.
Moreover, it was 2.2 nm when the crystallite measurement was performed similarly to Example 1. FIG.
[0039]
Example 4
A homogeneous solution was obtained by dissolving 45 g of stannic chloride and 5 g of K ₂ TiF ₆ in 2000 ml of distilled water at 30 ° C. This was then boiled for 2 hours to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 8 times. Add 1000 ml of distilled water to make the total volume 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution.
When the chloride ion concentration contained in the sol solution was determined using ion chromatography, 0.008 wt% chloride ion was contained.
A thin film was formed using this sol solution on a quartz plate in the same manner as in Example 1, and the volume resistivity after the heat treatment was determined to be 1.5 × 10 ⁴ Ωcm.
Moreover, it was 2.4 nm when the crystallite measurement was performed similarly to Example 1. FIG.
[0040]
Example 5
45 g of stannic chloride and 5 g of KF were dissolved in 2000 ml of distilled water at 30 ° C. to obtain a uniform solution. This was then boiled for 2 hours to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 8 times. Add 1000 ml of distilled water to make the total volume 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution.
When the chloride ion concentration contained in the sol solution was determined using ion chromatography, 0.008 wt% chloride ion was contained.
A thin film was formed using this sol solution on a quartz plate in the same manner as in Example 1, and the volume resistivity after the heat treatment was determined to be 6.5 × 10 ³ Ωcm.
Moreover, it was 2.1 nm when the crystallite measurement was performed similarly to Example 1. FIG.
[0041]
Comparative Example 3
A homogeneous solution was obtained by dissolving 65 g of stannic chloride hydrate and 1.0 g of antimony trichloride in 2000 ml of a 30 ° C. water / ethanol mixed solution. This was then boiled for 2 hours to obtain a coprecipitate. The produced precipitate is taken out by decantation, and the precipitate is washed with distilled water 40 times. Silver nitrate is dropped into distilled water from which the precipitate has been washed, and after confirming that there is no reaction of chlorine ions, 1000 ml of distilled water is added to make the total amount 2000 ml. Further, 40 ml of 30% aqueous ammonia was added and heated to 100 ° C. in a water bath to obtain a colloidal gel dispersion. A slightly reddish sol solution was obtained.
[0042]
As described above, from the comparison of Example 2, Example 3, Example 4, Example 5 and Comparative Example 3, the present invention can produce an amorphous tin oxide sol having no color and good conductivity. is there.
[0043]
【The invention's effect】
According to the present invention, coloration is no conductivity can be provided a method of manufacturing an amorphous oxide Suzuzo Le suitable for use in the transparent conductive material is good.

Claims (4)

A method for producing an amorphous tin oxide sol as shown below, after hydrolyzing a hydrolyzable tin compound and washing, the obtained halogen concentration of 0.001% to 3% is dissolved in ammonia water. A method for producing an amorphous tin oxide sol, wherein the heat treatment is carried out below the boiling point of water .
[Amorphous tin oxide sol]
An amorphous tin oxide sol having a long-range order in the atomic arrangement and a temperature range showing a change in the substance below the melting point (1127 ° C.) of crystalline tin oxide, and having a conductivity of less than 10 ⁵ Ωcm An amorphous tin oxide sol comprising crystalline tin oxide particles. A method for producing an amorphous tin oxide sol as shown below, wherein the halogen concentration obtained is hydrolyzed using a hydrolyzable tin compound and a fluorine-containing compound, and the resulting halogen concentration is 0.001% or more and 3% or less. A method for producing an amorphous tin oxide sol, wherein the raw material is dissolved in ammonia water and subjected to heat treatment at a temperature equal to or lower than the boiling point of water .
[Amorphous tin oxide sol]
An amorphous tin oxide sol having a long-range order in the atomic arrangement and a temperature range showing a change in the substance below the melting point (1127 ° C.) of crystalline tin oxide, and having a conductivity of less than 10 ⁵ Ωcm An amorphous tin oxide sol comprising crystalline tin oxide particles. 3. The amorphous tin oxide sol according to claim 1, wherein the amorphous tin oxide sol contains tin oxide that causes a weight loss of 0.1 wt% or more and less than 30 wt% in a range of 200 ° C. to 500 ° C. by heat treatment. A method for producing a tin oxide sol. The method for producing an amorphous tin oxide sol according to claim 1 or 2, wherein the amorphous tin oxide sol contains tin oxide containing at least 0.001 wt% or more of anions.