JPH0427168B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a crystalline titanium oxide-tin oxide sol and a method for producing the same, and relates to a crystalline titanium oxide-tin oxide sol and a method for producing the same. It is something that confers properties.

(Prior Art) Research and development of excellent dielectric materials has been actively conducted in recent years, and studies on dielectric materials and molding and firing methods are being conducted.

Among them, the perovskite type compound ABO ₃ (however,
A: Element with 12 coordinations of oxygen, B: Element with 6 coordinations of oxygen,
In order to reduce the energy loss of the dielectric (O: represents the oxygen element) and to improve other physical properties, titanium oxide, mainly titanium oxide, and other materials such as tin oxide are introduced as raw materials at the B element position. Studies are progressing on methods, and the challenge is how to uniformly add and mix these substances into materials. Research and development is also underway to apply materials such as titanium oxide and tin oxide to bulk oxygen sensor materials for air-fuel ratio control in automobile engines. In these applications, titanium oxide and tin oxide materials have particle diameters of 400 Å or less, and films coated with these materials are desired to have a film thickness of 0.1 μm or less.

As described above, there is a demand for a composite material of titanium oxide and tin oxide that has a small particle size and a uniform composition.

Titanium oxide powder, which is used as a raw material powder for these applications, is usually obtained by adding sulfuric acid or hydrochloric acid to ilmenite, hydrolyzing the salt to obtain metatitanic acid, and then filtering, drying, and calcining this. can. Similarly, tin oxide powder can also be obtained by filtering, drying, and calcining a product obtained by hydrolyzing stannic chloride.

When these materials are used in ceramic materials as described above, a powder-powder mixing method has conventionally been used. However, the powder mixing method results in non-uniform composition, and in order to solve this problem, a method has been found in which mixing is performed during hydrolysis during production of the raw material powder.

However, since the hydrolyzate produced by Shizure's method is a mixture, it does not have sufficient uniformity, and there is currently a demand for a more uniform composite material to replace this method.

(Problems to be Solved by the Invention) In view of these circumstances, the present inventors have worked diligently to obtain a crystalline titanium oxide-tin oxide sol that is excellent in various properties such as particle size, dispersibility, and uniformity. As a result of repeated research, a new crystalline titanium oxide-tin oxide sol was discovered and the present invention was completed.

(Means for solving the problems) That is, the present invention relates to a crystalline titanium oxide-tin oxide sol and a method for producing the same, and the first invention relates to a crystalline titanium oxide-tin oxide sol and a method for producing the same.
In line diffraction, the d (Å) value of each crystal plane, that is, (1,
1,0) plane d value (denoted by d ₁ ), (1,0,1) plane d value (denoted by _d2 ), (2,1,1) plane d value (d ₃
) are 3.247<d ₁ <3.351 and 2.487<
Particle size in the range of d ₂ < 2.644, 1.687 < d ₃ < 1.765
This invention relates to a crystalline titanium oxide-tin oxide sol of 500 Å or less.

The second invention also provides a method for producing a gel by reacting a water-soluble titanium compound and a water-soluble tin compound with an alkali metal hydroxide or its carbonate and/or ammonium compound, and then heating the gel at a temperature of 100°C or higher. The present invention relates to a method for producing a crystalline titanium oxide-tin oxide sol, which is characterized by hydrothermal treatment.

(Function) First, in X-ray diffraction, which is the first invention, the d (Å) value of each crystal plane, that is, the d value (denoted by d ₁ ) of the (1,1,0) plane, (1, The d value of the 0,1) plane (denoted by _d2 ) and the d value of the (2,1,1) plane (denoted by _d3 ) are 3.247< _d1 <3.351, 2.487< _d2 <2.644, respectively.
A crystalline titanium oxide-tin oxide sol with a particle size of 500 Å or less in the range of 1.687<d ₃ <1.765 will be described in detail.

Regarding the solid solution of titanium oxide and tin oxide,
NNPadurow (Naturwissenschaften, 43(17)
395-96 (1956)), M.PAPK et al. (J.Am.Ceram.Soc., 58 (1-2) 43-47 (1975))
has investigated and reported in detail. However, these products are made by mixing TiO ₂ and SnO ₂ of approximately 1 μm particles in powder form.
A solid solution is obtained by firing at 900°C or higher, and it is not a sol consisting of fine particles like the present invention.

In contrast, the crystalline titanium oxide-tin oxide sol of the present invention forms colloidal particles consisting of monodisperse particles of 500 Å or less in an aqueous solution state, thereby providing a stable sol solution.

Titanium oxide sols and tin oxide sols have been known for a long time, and it was easily possible to use a mixture of these. However, even if these single sols are mixed, the sol particles will only become a mixture of single substances, and the sol of the present invention, in which tin and titanium oxides are mutually dissolved, has a uniformity as a composite material. They are completely different.

The crystalline titanium oxide-tin oxide sol of the present invention is
According to the line diffraction method, it is completely different from a mixture in which the crystal peaks of the titanium oxide sol and tin oxide sol are superimposed, and it shows a state in which titanium oxide and tin oxide are in solid solution with each other. , which was completely unknown until now. Therefore, this product creates new uses in the field of application of conventional titanium oxide based composite materials.

In addition, the crystalline titanium oxide-tin oxide sol of the present invention has a d value of the (1,1,0) plane (hereinafter referred to as d ₁ ) in the measurement results of the d (Å) value of each crystal plane by X-ray diffraction method. ) 3.247 < d ₁ < 3.351, d value of (1, 0, 1) plane (hereinafter referred to as d ₂ ) 2.487 < d ₂ < 2.644, (2, 1, 1)
The d value of the surface (hereinafter referred to as d ₃ ) is in the range of 1.687<d ₃ <1.765.

The crystalline titanium oxide-tin oxide sol of the present invention is
The more tin oxide is added to titanium oxide in the composition, the closer d ₁ is to 3.351, the closer d ₂ is to 2.644, and the closer d ₃ is to
It will be close to 1.765. Conversely, for tin oxide,
The more titanium oxide there is, the closer d ₁ is to 3.247, and the closer d ₂ is to
It is close to 2.487, and d ₃ is close to 1.687.

That is, in the crystalline titanium oxide-tin oxide sol of the present invention, the d (Å) value of each crystal plane changes as the composition changes.
3.247<d ₁ <3.351, 2.487<d ₂ <2.644, 1.687<d ₃
It varies within the range <1.765.

In addition, a JCPDS card (Joint Committee on Powder Diffraction
According to Standards), tin oxide (1,1,
The d value of the 0) plane is 3.351, the d value of the (1,0,1) plane is 2.644, and the d value of the (2,1,1) plane is
It is 1.765.

In addition, titanium oxide (rutile type) (1,1,
The d value of the 0) plane is 3.247, the d value of the (1,0,1) plane is 2.487, and the d value of the (2,1,1) plane is
It is 1.687.

The d(Å) value was measured by the X-ray diffraction method of the present invention by drying the crystalline titanium oxide-tin oxide sol of the present invention at 100°C and using an X-ray diffraction apparatus (Rigaku Denki) as a specimen. 40KV, 15mA, using Mo tube.
Measured under the conditions of using a Monochromater.

The characteristics of the crystalline titanium oxide-tin oxide sol of the present invention are listed below.

First, the crystalline titanium oxide-tin oxide sol of the present invention has a lower
Since titanium oxide and tin oxide are incorporated into the crystal structure as a solid solution, they provide more uniform compositional characteristics and enhance the characteristic effects of additives in perovskite-type compounds.

Second, when creating a coating film, titanium oxide has poor sinterability at low temperatures during firing, but since tin oxide is dissolved in solid solution, it can be sintered at low temperatures.

The crystalline titanium oxide-tin oxide sol of the present invention having the above-mentioned excellent characteristics is very useful as a titanium oxide-tin oxide composite material, and can be used, for example, in dielectric materials, piezoelectric materials, and sensor materials. It is a novel substance that can be applied to applications such as special glass coating materials that have both ultraviolet absorption and infrared reflection functions, imparting functionality to plastics, and many other applications.

Next, the second invention, crystalline titanium oxide
The method for producing tin oxide sol will be described in detail.

The second invention involves reacting a water-soluble titanium compound and a water-soluble tin compound with an alkali metal hydroxide or its carbonate and/or ammonium compound to form a gel, and then heating the gel at 100°C or higher. Crystalline titanium oxide characterized by hydrothermal treatment
The present invention relates to a method for producing tin oxide sol.

The water-soluble titanium compound used in the present invention includes:
Examples include titanium tetrachloride, titanium nitrate, and titanium sulfate. Examples of water-soluble tin compounds include stannic chloride and stannic nitrate.

Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and lithium hydroxide, and examples of alkali metal carbonates include sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. .

Further, examples of ammonium compounds include ammonium bicarbonate, ammonium carbonate, aqueous ammonia, etc., but are not limited thereto.

In the present invention, first of all, the water-soluble titanium compound and water-soluble tin compound are reacted with an alkali metal hydroxide or its carbonate and/or ammonium compound to form a gel.

In this case, there is no particular limitation on the order of these additions; either an alkali metal hydroxide or the like is added to the titanium compound and the tin compound, or the titanium compound and the tin compound are reacted separately with an alkali metal hydroxide or the like. Any addition method can be adopted, such as mixing the two after obtaining the gel.
However, a method in which a mixed solution of a titanium compound and a tin compound is added to an aqueous solution of an alkali metal hydroxide or the like is preferred in that a uniform gel can be obtained.

Furthermore, the temperature during gel formation may be room temperature, and there is no need to perform special operations such as heating and cooling.

In addition, regarding the usage ratio, the equivalent ratio A/B of the alkali metal hydroxide or its carbonate and/or ammonium compound (A) and the acid radical (B) derived from the water-soluble titanium compound and water-soluble tin compound
is approximately in the range of 0.9 to 1.3. Further, the ratio of the water-soluble titanium compound and the water-soluble tin compound to be used may be appropriately selected depending on the intended use of the sol of the present invention.

The gel thus produced is then washed to remove impurities. At this time, residual impurities in the gel are
The smaller the amount, the better; for example, if the above-mentioned washing operation is not performed at all, the resulting sol will be unstable.

The cleaning means is not particularly limited, and any commonly used means such as filter press, water injection filtration cleaning such as centrifugal filtration, repulp-centrifugation method, etc. can be used.

When an alkaline ion-stabilized sol is desired, a water-soluble alkali is added to the gel after washing, and when an acidic ion-stabilized sol is desired, a water-soluble acid is similarly added and subjected to hydrothermal treatment. .

Examples of the water-soluble alkali to be added include ammonium hydroxide, sodium hydroxide, potassium hydroxide, methylamine, trimethylamine, ethylenediamine, and ethanolamine.

Examples of the water-soluble acid to be added include hydrochloric acid, nitric acid, acetic acid, formic acid, and glycolic acid.

In addition, the amounts of these additions are generally TiO ₂ and SnO ₂
The amount is in the range of 0.01 to 0.6 mol per 1 mol of the total amount. In this case, if the amount added deviates from this range,
The viscosity of the gel increases significantly, making it difficult to obtain a sol with excellent dispersibility according to the present invention.

Regarding the hydrothermal treatment conditions, the temperature is 100℃ or higher, but in general, the higher the treatment temperature and the longer the treatment time, the better the development of crystal form and the better the ability to obtain a sol consisting of colloidal particles with a large particle size. I can do it.

In addition, if the treatment is carried out at a temperature below 100℃, the gel will not crystallize even if it is carried out for a long time, and even if a part of it crystallizes, the degree of crystallinity will be extremely low and it will remain amorphous, leaving the original The purpose of the invention cannot be achieved.

The hydrothermal treatment conditions can be selected according to each use of the crystalline titanium oxide-tin oxide sol of the present invention, and a sol with a desired particle size can be obtained, and this can be controlled by selecting the hydrothermal treatment conditions. This is a major feature of the present invention.

(Example) The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. In addition, unless otherwise specified, all % indicates weight %, and all d(Å) values abbreviate units.

Example 1 141.5 g of a stannic chloride aqueous solution (SnO ₂ 10.0%) was added to 1000 g of a titanium tetrachloride aqueous solution (TiO ₂ 3.0%) to form a uniform solution. To this solution, 1690 g of aqueous ammonia (NH ₃ 2.0%) was added over a period of about 1 hour with stirring, and a gel was obtained by performing a reaction. still,
The temperature of the reaction solution at this time was 25°C.

This gel was filtered and washed with water until no chloride ions were observed in the filtrate, and the composition of the gel was determined to be TiO ₂
A gel containing 7.09%, _SnO2 3.34%, and _NH3 0.27% was obtained.

Add 300g of this gel to ammonia water (NH ₃ 2.0%)
Add 16.0g and 109.5g of water, put this in an autoclave, and perform hydrothermal treatment at 200℃ for 6 hours.
A crystalline titanium oxide-tin oxide sol of the present invention was obtained.

Note that the pH of this sol solution was 10.5.

Further, when this sol was diluted to a TiO ₂ concentration of 0.5% and stored stationary, no sediment was observed even after one month had passed, and the sol solution was in a stable state.

Furthermore, the particle size was measured by transmission electron microscopy, and the particle size was 60 Å. The transmission electron microscope device is JEM- manufactured by JEOL Ltd.
200CX type was used.

This sol was dried at 100°C for 30 minutes and measured by X-ray diffraction. As a result, d ₁ was 3.310, d ₂ was 2.556,
d ₃ was 1.713. Moreover, the X-ray diffraction diagram is shown in the first place.

Example 2 2000 g of titanium sulfate aqueous solution (TiO ₂ 2.0%) and 2000 g of stannic sulfate aqueous solution (SnO ₂ 3.8%) were placed in separate containers, and each was added to sodium bicarbonate aqueous solution (SnO 2 3.8%) at the same addition rate using a metering pump. Na1.4%)
A gel was obtained by gradually adding the solution to 7264 g of the solution under stirring and carrying out the reaction.

After filtering the generated gel, water injection filtration and washing were performed until sodium ions and sulfate groups were no longer observed in the gel.

As a result, the composition of the gel was 10.46% _SnO2 , _TiO2
A 5.5% gel was obtained.

Next, 2.0 g of triethanolamine and 100 g of water were added to 100 g of this gel to form a uniform gel slurry, which was then transferred to an autoclave and subjected to hydrothermal treatment at 200°C for 6 hours to form the crystalline titanium oxide of the present invention. A tin oxide sol was obtained.

This sol was dried at 100°C for 30 minutes and measured by X-ray diffraction. As a result, d ₁ was 3.324, d ₂ was 2.572,
d ₃ was 1.731. Moreover, the X-ray diffraction diagram is shown in the second figure.

Furthermore, the fourth enlarged photograph taken with a transmission electron microscope is
Shown in the figure.

Example 3 410 g of ammonia water (NH ₃ 1.0%) was added to 156 g of titanium tetrachloride aqueous solution (TiO ₂ 3.0%) at room temperature while stirring.
A gel was obtained by gradually adding and reacting over a period of 0.4 hours.

This gel was filtered and washed with water until no chloride ions were observed in the filtrate, and the composition of the gel was determined to be TiO ₂
A gel of 4.8% and 0.02% _NH3 was obtained.

Then ammonium bicarbonate aqueous solution (NH ₃ 3.1%)
200g of stannic chloride aqueous solution (SnO ₂ 17.6%) in 564g
was gradually added over a period of about 0.2 hours while stirring at room temperature.
A gel was obtained by the reaction.

This gel was filtered and washed with water until no chloride ions were observed in the filtrate, and the composition of the gel was determined to be SnO ₂
A gel containing 35.2% and 0.04% _NH3 was obtained.

50g of gel obtained from this aqueous solution of tinnic chloride and 48.6g of gel obtained from the aqueous solution of titanium tetrachloride were added to water.
The mixture was added to a solution containing 83.6 g of NH 3 and 17.8 g of aqueous ammonia (NH ₃ 4.0%), and stirred to mix uniformly.

This was transferred to an autoclave and subjected to hydrothermal treatment at 200°C for 6 hours to obtain the crystalline titanium oxide-tin oxide sol of the present invention.

This sol was dried at 100°C for 30 minutes and measured by X-ray diffraction. As a result, d ₁ was 3.337, d ₂ was 2.613,
_d3 was 1.749. Moreover, the X-ray diffraction diagram is shown in FIG.

Example 4 200 g of titanium tetrachloride aqueous solution (TiO ₂ 16.4%), 616 g of stannic chloride aqueous solution (SnO ₂ 10.0%) and 2632 g of water
was added to make a homogeneous solution. To this solution, 1280 g of aqueous ammonia (NH ₃ 4.14%) was added over about 0.5 hours with stirring, and a gel was obtained by performing a reaction.

This gel is filtered and washed with water, and the composition of the gel is TiO ₂
A gel of 5.80%, SnO ₂ 10.94%, and Cl 0.25% was obtained.

To 100.0g of this gel, 101.5g of water, hydrochloric acid (HCl10
%) was added thereto and made uniform, and this was placed in an autoclave and subjected to hydrothermal treatment at 150° C. for 15 hours to obtain the crystalline titanium oxide-tin oxide sol of the present invention.

This sol was dried at 100°C for 30 minutes and measured by X-ray diffraction. As a result, d ₁ was 3.324, d ₂ was 2.572,
d ₃ was 1.731.

[Brief explanation of drawings]

Figures 1 to 3 show the crystalline titanium oxide-tin oxide sols of the present invention obtained in Examples 1 to 3 at 100°C.
The X-ray diffraction diagram of the dried product, FIG. 4, is an enlarged photograph taken with a transmission electron microscope of the crystalline titanium oxide-tin oxide sol of the present invention obtained in Example 2.

Claims (1)

[Claims] 1. In X-ray diffraction, the d (Å) value of each crystal plane, that is, the d value (denoted by d ₁ ) of the (1,1,0) plane, (1,0,
1) d value of the surface (denoted by d ₂ ), d of the (2,1,1) surface
The values (denoted by d ₃ ) are 3.247 < d ₁ < 3.351, respectively.
A crystalline titanium oxide-tin oxide sol with a particle size of 500 Å or less in the range of 2.487<d ₂ 2.644, 1.687<d ₃ <1.765. 2. Reacting a water-soluble titanium compound and a water-soluble tin compound with an alkali metal hydroxide or its carbonate and/or ammonium compound to form a gel, and then hydrothermally treating the gel at 100°C or higher. A method for producing a characterized crystalline titanium oxide-tin oxide sol.