JPH1059720A - Amorphous tin oxide sol and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an amorphous tin oxide sol free from coloring, excellent in conductivity and suitable as a transparent conducting material by hydrolyzing a hydrolyzable tin compound, performing washing, then, dissolving the resultant raw material having a specific halogen concn. in an aq. ammonia and performing heat treatment. SOLUTION: The amorphous tin oxide sol is obtained by hydrolyzing the hydrolyzable tin compound after cleaning and dissolving the resultant raw material having 0.001-3% halogen concn. in the aq. ammonia and heat treating. As the hydrolyzable tin oxide, a compound containing an oxo anion such as K2 SnO3 .3H2 O, a water soluble halide such as SnCl4 , SnCl4 .5H2 O and the like are exemplified. The heat treatment is preferably performed at 25-150 deg.C. The amorphous tin oxide sol contains an amorphous tin oxide particle having <10<5> Ωcm conductivity and a tin oxide causing >=0.1wt.% to <30wt.% weight decrease at 200-500 deg.C by heat treating (by the measurement of general thermogravimetric analysis).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an amorphous tin oxide sol and a method for producing the same.

[0002]

2. Description of the Related 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 foreign atoms. Further, it is a material having excellent transparency and physical and chemical stability, and is expected to be used for electric and electronic applications.

[0003] Such a tin oxide is famous for its transparent conductive oxide film formed of a complex with antimony or indium, and has many uses. However, high-purity tin oxide or amorphous tin oxide has low conductivity. Not much considered for.

[0004] As for these materials, as described in the Research Report on Inorganic Materials, No. 35, "Study on Tin Oxide" published by the Science and Technology Agency, other than doping or compounding of a specific metal compound. Does not exhibit high conductivity. When the purity is increased, the semiconductor region becomes a semiconductor region, and its conductivity reaches 10 ⁶ Ωcm or more. Therefore, many attempts have been made to increase the conductivity in order to use it for applications of transparent conductive materials.

The transparent conductive material is generally used after being coated on a substrate by a film forming method such as a chemical vapor deposition method, a vacuum vapor deposition method, a reactive ion plating method, a sputtering method and an ion beam sputtering method.

However, all of these methods have disadvantages that not only are the devices expensive, complicated and large, but the film forming speed is low and a large-area film cannot be obtained. Further, when a film having a complicated shape is formed, the film tends to be non-uniform, and there are many restrictions on its use.

On the other hand, a method of dipping and applying a liquid material onto a substrate, a method of applying by spraying, and a method of applying using a pneumatic doctor, a bar coater, or the like are relatively easy to apply to a large area. A membrane is obtained,
This method can be applied relatively easily to a part having a complicated shape, and is an industrially promising method. Such coating methods have been widely studied for tin oxide based materials.

[0008] Tin oxide-based materials which have been studied so far are mainly salt solutions of organic or inorganic compounds containing both tin and antimony as ions. Therefore,
When using a salt solution of an organic compound, thermal decomposition must be carried out carefully so that no organic matter remains, and tin and antimony are diffused as organic salts, and the polarity of the solution is low and the solution is compatible with substrates such as glass. No uniform film could be obtained.

Further, as a result of requiring a large amount of a stabilizing agent to maintain the liquid stability of the organic salt, only a thin film having a small film thickness is obtained, and a multi-layer dip is carried out after drying because of a large amount of an organic substance. There were problems such as peeling during firing.

Furthermore, tin oxide / antimony produced during thermal decomposition generally has a coarse particle size, and there is a problem in particular when applied to a field where uniform fineness is required. 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.

However, according to these techniques, the sol solution is colored, the surface smoothness is deteriorated when the sol is applied because the sol solution is crystalline, and high conductivity is not exhibited unless fired once. And so on.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide an amorphous tin oxide sol suitable for use as a transparent conductive material which is free from coloring and has good conductivity, and a method for producing the same.

[0013]

The above objects of the present invention are as follows. Amorphous tin oxide sol, comprising amorphous tin oxide particles having a conductivity of less than 10 ⁵ Ωcm,

2. 200 ℃ to 500 ℃ by heat treatment
An amorphous tin oxide sol comprising tin oxide which causes a weight loss of 0.1 wt% (wt%; the same applies to all in the present specification) in the range of not more than 30 wt%.

3. An amorphous tin oxide sol comprising tin oxide containing at least 0.001 wt% or more of an anion;

4. After the hydrolyzable tin compound is hydrolyzed and washed, the obtained halogen concentration is 0.001% or more 3
% Or less of the raw material is dissolved in aqueous ammonia and subjected to a heat treatment.

5. After hydrolyzing with a hydrolyzable tin compound and a compound containing fluorine and washing, the obtained raw material having a halogen concentration of 0.001% or more and 3% or less is dissolved in aqueous ammonia to perform heat treatment. This is achieved by a method for producing an amorphous tin oxide sol.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below. First, in the present invention, amorphous means a substance different from crystalline. Crystallinity refers to the 72nd volume of Electrical and Electronics Engineering, Crystal Evaluation (Tsuji Ito, Nao Inuzuka, Corona,
As described on page 4 of 1982), the arrangement of atoms has a long-range order and the substance has a solid-state melting point. For example, it is known that high purity, colorless and transparent crystalline tin oxide has a tetragonal rutile structure, a refractive index of 1.9968, and a high electrical conductivity of at least 10 ⁶ Ωcm at room temperature. Have been. The melting point is 112
The temperature is 7 ° 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, there is no long-range order in the arrangement of atoms, and there is a temperature region that shows a change in the substance below the melting point of crystalline tin oxide. It can be called tin oxide.

Regarding the structure, it is possible to identify its structure by X-ray diffraction. From the measurement of the crystallite size described in the new edition of Karity X-ray Diffraction (Translated by Gentaro Matsumura, Agne, 1977), the length can be determined. 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, and crystalline tin oxide must have several tens or more repeating units. Values are observed. Therefore, if it is less than 10 nm in the crystallite measurement, it cannot be said that there is any longer-range order, and it is considered to be amorphous. 5n
m, it is 10 if the repeating unit is no longer assumed.
It is less than the number of crystals and is not a crystal.

The fact that the thermal analysis of a solid is made clear becomes easy, and even if the effects of the measurement conditions and the size of the sample are taken into consideration, if a thermal change occurs below 1000 ° C., it cannot be said that the crystal is a crystal. A thermogravimetric analysis that can be easily observed by a thermal change is a thermogravimetric analysis, in which the weight loss at 200 ° C. is 0.1 wt% or more in the temperature range up to 500 ° C., which is much lower than the melting point, and is much lower than the melting point. Not a single crystal tin oxide. As described above, in the case of tin oxide satisfying or satisfying the above conditions, it is clearly amorphous.

Next, the conductivity means the conductivity of the tin oxide particles, and any measuring method may be used as long as the conductivity can be accurately evaluated. The measurement examples are shown below, but do not limit the present invention.

A thin film of tin oxide is formed on a quartz plate at 200 ° C.
Perform the treatment in air. Measure thickness of thin film at room temperature 25 ℃
Then, the resistance was measured by the four-terminal method, and from this resistance value and the film thickness,
Find the volume resistivity. The volume solid determined by such a method
Resistance is 10 ^-2Ωcm or more 10⁵Acid showing less than Ωcm
The sol containing tin oxide particles is the tin oxide sol of the present invention.

The weight loss by the heat treatment means a value measured by a thermogravimetric analysis generally used. The heating rate is preferably 30 ° C./min or less, more preferably 1 ° C./min.
It is a sol containing tin oxide, which is measured at a temperature of 0 ° C./min or less and causes a weight loss of 0.1 wt% or more and less than 30 wt% in a range of 200 ° C. to 500 ° C.

The sol of the present invention is heated up to 200 ° C. in air.
Or N ₂When heated in a non-oxidizing atmosphere such as Ar or Ar,
It becomes amorphous tin oxide. If it is crystalline tin oxide,
And no thermal change in the treatment at 200 ° C. or higher. Non
Amorphous tin oxide shows weight loss of 0.1 wt% or more
You. The relationship between this weight loss and conductivity is not clear
However, the present inventors found that tin oxide particles showing weight loss
Have been found, leading to the present invention.

Good results are obtained when impurity ions such as cations such as ammonium ions and hydrogen ions and anions described below are present.

The presence of anions is not particularly defined, but the presence of any organic or inorganic ions shows higher conductivity. Particularly preferred are an ion containing a carboxylic acid group or a sulfonic acid group, an amino group, a hydroxyl group, a carbonate ion and a halogen ion. Even if these ions exist inside the amorphous tin oxide particles,
It may be present outside or both inside and outside. However, as for the amount present, it is not preferable that the amount of the external component such as the surface is 30 wt% or more with respect to the particle because a problem occurs in the stability of the sol.
% Is preferred, more preferably less than 10 wt%, particularly preferably less than 6 wt% is selected because of good stability when formed into a sol. The amount of the anion present inside the particle is not specified because it does not affect the stability of the sol, but is preferably 0.001% by weight or more and less than 6% by weight.

The method for producing these tin oxide sols is not particularly limited, and the method described in claim 4, that is, after the hydrolyzable tin compound is hydrolyzed and washed, the obtained halogen concentration is 0.001% A method in which at least 3% or less of the raw material is dissolved in ammonia water and subjected to a heat treatment, the method according to claim 5, that is, a hydrolysis treatment using a hydrolyzable tin compound and a compound containing fluorine, followed by washing. Any method may be used, such as a method in which a raw material having a halogen concentration of 0.001% or more and 3% or less is dissolved in aqueous ammonia and subjected to heat treatment.

In the production method of the present invention, the temperature condition of the compound containing Sn in the entire production process is important,
The method involving a high-temperature heat treatment is not preferable because it causes the growth of primary particles and a phenomenon that the crystallinity increases, and when heat treatment needs to be performed, it is 450 ° C. or less, particularly 300 ° C. or less, preferably 200 ° C. or less, More preferably 150 ° C
The following is assumed. However, heating from 25 ° C to 150 ° C is a preferred means.

The production process includes three processes: a process of hydrolyzing the hydrolyzable tin compound and a process of converting the obtained precipitate into a sol through a washing process. The present invention does not limit that each step takes a more subdivided step. For example, the hydrolysis step is composed of a step of measuring and charging the raw materials, a step of mixing with components added for hydrolysis, a heating step, and the like. Do not limit this. The washing step involves a solid-liquid separation step, and the method may be any method such as a method using an appropriate filter such as decantation or ultrafiltration. The same applies to the formation of a sol. An additive, a solvent, and the like added for stably dispersing the particles are not limited, but stabilization of the sol with ammonia water is preferable in terms of economy.

The compounds used in the production method according to claim 4 will be described below. What is a hydrolyzable tin compound?
K ₂ SnO ₃ · 3H ₂ compounds containing oxo anions such as _O, SnCl 4, water-soluble halides, such as _{SnCl 4 · 5H 2 O, R} '2 SnR 2, R 3 SnX, R 2
SnX ₂ [R ′ is an aliphatic or aromatic organic compound,
R represents an aliphatic or aromatic organic compound, and X represents a halogen. Having a structure of, for example, (CH ₃ ) ₃ S
nCl · (pyridine), (C ₄ H ₉ ) ₂ Sn (O ₂ CC
₂ H ₅₎ organometallic compounds such as _{2, Sn (SO 4) 2} · 2
Oxo salts such as H ₂ O can be mentioned.

In the method for producing a hydrolyzable tin compound from a decomposition reaction in a solvent, a compound containing an element other than Sn that is soluble in the solvent can be added during the process. For example, addition of a fluorine-containing compound soluble in a solvent or addition of a carbonate. The fluorine-containing compound soluble in the solvent may be either ionic fluoride or covalent fluoride, for example, HF or KHF ₂ , SbF
₃ , metal fluoride such as MoF ₆ , NH ₄ MnF ₃ , NH
A compound that generates a fluoro complex anion such as ₄ BiF ₄ ;
Inorganic molecular fluorides such as BrF ₃ , SF ₄ and SF ₆ , C
Organic fluorine compounds such as F ₃ I, CF ₃ OOH, and P (CF ₃ ) ₃ can be mentioned.
A combination of a fluorine-containing compound and a nonvolatile acid such as a combination of aF ₂ and sulfuric acid can also be used.

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. The washing method is not particularly limited, and examples thereof include a method using decantation and a method using an ultrafiltration membrane.

[0033]

Embodiments of the present invention will be described below. Example 1 45 g of stannic chloride was dissolved in 2000 ml of 30 ° C. water containing carbon dioxide to obtain a homogeneous solution. Then this is 2
Boil for an hour to obtain a coprecipitate. The formed precipitate is taken out by decantation, and the precipitate is washed with distilled water 10 times. Add 1000 ml of distilled water, and add 2000 ml
And Further, 40 ml of 30% aqueous ammonia was added, and the mixture was heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution.
A quartz plate is dipped in this sol solution and dried. This operation was repeated 100 times to form a tin oxide thin film on the quartz plate. 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.
× 10 ⁴ Ωcm. The sol solution was dried using a spray drying device, and powder was taken out of the sol solution. Using this powder, a crystallite measurement on the (100) plane was performed by powder X-ray diffraction, and it was found to be 2.1 nm, confirming that the powder was an amorphous powder. The thermogravimetric analysis of this powder was performed at a temperature rising rate of 10 ° C./min. After a gradual decrease in weight of 1.0 wt% up to 200 ° C., a 2.5 wt% increase from 200 ° C. to 500 ° C. Showed weight loss.

Comparative Example 1 65 g of stannic chloride hydrate was added to 2000 ml of distilled water
It was dissolved at 0 ° C. to obtain a homogeneous solution. Then, this was boiled to obtain a coprecipitate. The generated precipitate is taken out by decantation, and the precipitate is washed with distilled water 40 times. Silver nitrate was dropped into distilled water from which the precipitate had been washed, and after confirming that there was no reaction of chloride ions, 1000 ml of distilled water was added to reduce the total amount to 2 ml.
000 ml. In addition, 40% of 30% ammonia water
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 a quartz plate in the same manner as in Example 1, the volume resistivity was measured by a four-terminal method.
It was 1 × 10 ⁵ Ωcm. Further, when the crystallite measurement was performed, it was measured to be 3.1 nm.

COMPARATIVE EXAMPLE 2 65 g of stannic chloride hydrate was mixed with 2,000 m of distilled water at 30.degree.
to obtain a homogeneous solution. Then, this was boiled to obtain a coprecipitate. The generated precipitate is taken out by decantation, and the precipitate is washed with distilled water 40 times. 80 after washing
The powder was taken out by spraying into a cylindrical electric furnace at 0 ° C. This powder was dispersed in 2000 ml of water, 40 ml of 30% aqueous ammonia was added, and the mixture was heated to 100 ° C. in a water bath to obtain a colloidal gel dispersion. The resulting sol solution was slightly cloudy. After a thin film was formed on a quartz plate by the same method as in Example 1, the volume resistivity was measured by a four-terminal method, and it was 7.1 × 10 ⁶ Ωcm. Also,
When the crystallite measurement was performed, it was measured to be 30.5 nm.

As described above, it is apparent from Example 1 and Comparative Examples 1 and 2 that the tin oxide obtained has a small volume resistivity due to a slight difference in production conditions.

Example 2 45 g of stannic chloride was dissolved in 2000 ml of distilled water at 50 ° C. to obtain a homogeneous solution. Then, the mixture was boiled for 2 hours to obtain a coprecipitate. The formed precipitate is taken out by decantation, and the precipitate is washed with distilled water eight times. Distilled water 100
Add 0 ml to make the total volume 2000 ml. 30% more
40 ml of aqueous ammonia was added, and the mixture was heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution. When the concentration of chloride ions contained in the sol solution was determined using ion chromatography, it was found to contain 0.008 wt% chloride ions. 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. Further, the crystallite measurement was performed in the same manner as in Example 1, and it was 2.7 nm.

Example 3 45 g of stannic chloride was dissolved in 2000 ml of distilled water at 40 ° C. to obtain a homogeneous solution. Then, the mixture was boiled for 2 hours to obtain a coprecipitate. The formed precipitate is taken out by decantation, and the precipitate is washed with distilled water seven times. Distilled water 100
Add 0 ml to make the total volume 2000 ml. 30% more
40 ml of aqueous ammonia was added, and the mixture was heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution. When the concentration of chloride ions contained in the sol solution was determined using ion chromatography, it was found to contain 0.016 wt% chloride ions. 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. Further, the crystallite measurement was performed in the same manner as in Example 1, and it was 2.2 nm.

Example 4 45 g of stannic chloride and 5 g of K ₂ TiF ₆ were dissolved in 2000 ml of distilled water at 30 ° C. to obtain a homogeneous solution. Then, the mixture was boiled for 2 hours to obtain a coprecipitate. The formed precipitate is taken out by decantation, and the precipitate is washed with distilled water eight times. 1000 ml of distilled water is added and the total amount is 2000 m
l. Further, add 40 ml of 30% ammonia water,
The mixture was heated to 100 ° C. in a water bath to obtain a colorless and transparent sol solution. When the chlorine ion concentration contained in the sol solution was determined using ion chromatography, the concentration was 0.008 wt.
% Chloride ions. A thin film was formed on a quartz plate using this sol solution in the same manner as in Example 1, and the volume resistivity after heat treatment was 1.5 × 10 ⁴ Ωcm. Further, the crystallite measurement was performed in the same manner as in Example 1, and it was 2.4 nm.

Example 5 45 g of stannic chloride and 5 g of KF were mixed with distilled water at 30 ° C.
The solution was dissolved in 00 ml to obtain a homogeneous solution. Then, the mixture was boiled for 2 hours to obtain a coprecipitate. The formed precipitate is taken out by decantation, and the precipitate is washed with distilled water eight times.
Add 1000 ml of distilled water to make the total volume 2000 ml.
Further, 40 ml of 30% ammonia water was added, and 1 ml was added in a water bath.
The mixture was heated to 00 ° C. to obtain a colorless and transparent sol solution. When the concentration of chloride ions contained in the sol solution was determined using ion chromatography, it was found to contain 0.008 wt% chloride ions. A thin film was formed on a quartz plate using this sol solution 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. Also,
The crystallite measurement was performed in the same manner as in Example 1.
m.

Comparative Example 3 65 g of stannic chloride hydrate and 1.0 g of antimony trichloride
Was dissolved in 2000 ml of a 30 ° C. water / ethanol mixed solution to obtain a homogeneous solution. Then, the mixture was boiled for 2 hours to obtain a coprecipitate. The generated precipitate is taken out by decantation, and the precipitate is washed with distilled water 40 times. Silver nitrate was dropped into distilled water from which the precipitate was washed, and after confirming that there was no reaction of chloride ions, 1000 ml of distilled water was added and the total amount was 200.
Make it 0 ml. Further, 40 ml of 30% aqueous ammonia was added, and the mixture was heated to 100 ° C. in a water bath to obtain a colloidal gel dispersion. A slightly reddish sol solution was obtained.

As described above, from the comparison between Example 2, Example 3, Example 4, Example 5, and Comparative Example 3, the present invention has no coloring.
It is possible to produce a tin oxide sol having good conductivity.

[0043]

According to the present invention, it is possible to provide an amorphous tin oxide sol suitable for use as a transparent conductive material which is free from coloring and has good conductivity, and a method for producing the same.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nao Arimoto 1 Sakuramachi, Hino-shi, Tokyo Konica Corporation (72) Inventor Takahiro Sakazaki 2-18-35, 18-835, 18-8, Yodogawa-ku, Osaka-shi, Osaka Inside Yamanaka Chemical Co., Ltd.

Claims (5)

[Claims] 1. An amorphous tin oxide sol comprising amorphous tin oxide particles having a conductivity of less than 10 ⁵ Ωcm. 2. An amorphous tin oxide sol comprising tin oxide which causes a weight loss of from 0.1 wt% to less than 30 wt% in the range of 200 ° C. to 500 ° C. by heat treatment. 3. An amorphous tin oxide sol comprising tin oxide containing at least 0.001 wt% or more of anions. 4. A method comprising subjecting a hydrolyzable tin compound to hydrolysis treatment and washing, dissolving a raw material having a halogen concentration of 0.001% or more and 3% or less in ammonia water, and performing heat treatment. A method for producing an amorphous tin oxide sol. 5. A hydrolysis treatment using a hydrolyzable tin compound and a compound containing fluorine, followed by washing. Then, the obtained raw material having a halogen concentration of 0.001% to 3% is dissolved in aqueous ammonia and heated. A method for producing an amorphous tin oxide sol, comprising performing a treatment.