JPS63156016A - Production of sol of crystalline tin oxide-antimony oxide - Google Patents

Abstract

PURPOSE:To obtain a sol of crystalline tin oxide-antimony oxide having superior characteristics and to prevent discharge of Sb compd. into waste water in order to maintain good environmental condition, by adding Sb2O3 and ammonia to a gel obtd. by the reaction of a Sn compd. with an alkali bicarbonate, and treating the mixture hydrothermally. CONSTITUTION:After forming a gel by allowing a Sn compd. to react with an alkali bicarbonate or ammonium bicarbonate, Sb2O3 and ammonia are added to the gel, and the mixture is treated hydrothermally. Suitable Sn compds. are stannic chloride, stannic sulfate, etc. The amt. of the Sb2O3 to be added is pref. the amt. corresponding to <=0.3 molar ratio (Sb/Sn) contained in the gel.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a crystalline tin oxide antimony sol.

Tin oxide and antimony oxide compounds have excellent electrical conductivity, optical transparency, physical and chemical fire resistance, etc., and combined with the remarkable development of electro-optical devices in recent years, the demand for transparent conductive materials has increased dramatically. It is a rapidly growing industrial material.

(Prior art) Such transparent conductive materials are usually coated onto a substrate in the form of a film by a film forming method such as a CVD method, a vacuum evaporation method, a reactive ion blasting method, or a sputtering method, and are not put into practical use. It is offered.

However, all of these methods not only have the drawbacks of complicated equipment and slow film formation speed, but also
There is a problem in that the film is formed on a small area and a film with a large area cannot be obtained.

On the other hand, the so-called coating method, in which a liquid raw material is dipped onto a substrate to form a film, has the advantage that a large-area thin film can be obtained through a relatively simple process, and is an industrially promising method.

This coating method has been widely studied for tin oxide/antimony based materials, and the thermal decomposition behavior of a wide variety of liquid tin/antimony compounds has been studied.

However, the tin-antimony-based materials that have been studied so far are salt solutions of inorganic or organic compounds that mainly contain both tin and antimony as ions, so after coating them on a substrate, it is necessary to use tin oxide. - A firing process was required to turn it into antimony. Therefore, the tin oxide and antimony produced at this time generally have coarse and uneven particle sizes, making it difficult to obtain a uniform film.
In particular, there have been problems with application to fields that require uniform fineness.

In addition, when using compounds such as stannic chloride and antimony trichloride, it is necessary to select a furnace because harmful and corrosive gases are generated during firing, and the work environment may not be suitable. This is the current situation.

(Problems to be Solved by the Invention) In view of these circumstances, the present inventors have developed a crystalline material that is excellent in various properties desired when applied to transparent conductive materials and other ceramic material fields. As a result of intensive research to obtain a tin oxide/antimony sol, we discovered that a crystalline tin oxide/antimony sol with a particle size of 300λ or less in which Sb and Sn are dissolved in solid solution at an Sb/Sn molar ratio of 0.3 or less is superior. I applied first. (Patent Application No. 61-63657) However, this crystalline tin oxide antimony sol is produced by reacting a tin compound and an antimony compound with an alkali metal bicarbonate or an ammonium bicarbonate to form a gel, and then adding ammonia. As a result of the hydrothermal treatment method, in the process of washing and removing impurities in this gel, unreacted antimony compounds may flow out into wastewater, which may cause problems with the toxicity of antimony compounds or the recovery of antimony. There was also an economical problem because of the process required.

Therefore, the present inventors have conducted further studies on the manufacturing method in order to avoid these problems and obtain an excellent crystalline tin oxide antimony sol, and as a result, they have arrived at the present invention.

(Means for Solving the Problems) That is, in the present invention, a tin compound is reacted with an alkali metal bicarbonate salt or an ammonium bicarbonate salt to form a gel, and then diantimony dioxide and ammonia are added, followed by hydrothermal treatment. The present invention relates to a method for producing a crystalline tin oxide antimony sol.

However, the sol obtained by the production method of the present invention has sb and Sn in solid solution at an Sb/Sn molar ratio of 0.3 or less, as described in the patent previously filed by the present inventors (Japanese Patent Application No. 61-63657). It is exactly the same as the crystalline tin oxide antimony sol with a particle size of 300 s or less.

The term "crystalline tin oxide/antimony" as used herein refers to tin oxide containing antimony oxide as a solid solution, which is identified as cassiterite by X-ray diffraction.

(Function) The method for producing the crystalline tin oxide/antimony sol of the present invention will be described in further detail below.

In the present invention, first of all, a tin compound and an alkali metal bicarbonate or an ammonium bicarbonate are reacted to obtain a gel.

Examples of the tin compound used in the present invention include stannic chloride and stannic sulfate, and examples of the alkali metal bicarbonate include sodium bicarbonate and potassium bicarbonate. However, the present invention is not limited thereto.

Further, if a gel manufactured using raw materials other than those mentioned above is used in the present invention, the object of the present invention cannot be achieved.

That is, gels produced using sodium carbonate, sodium hydroxide, ammonia, etc. in place of the bicarbonate have poor filterability and are susceptible to aging, and even if this gel is subjected to the treatment described below, the present invention will not work. It is not possible to produce a crystalline tin oxide/antimony sol with such excellent dispersibility.

Next, the ratio of the alkali metal bicarbonate or ammonium bicarbonate to the tin compound is such that the pH of the solution at the end of the gel formation reaction is 6 or more. do.

If the amount of the alkali metal bicarbonate or ammonium bicarbonate used is smaller than this, the tin compound will not be completely gelled and the yield will be poor, which is not preferred for economic reasons.

There is no particular limitation on the order in which the tin compound and the alkali metal bicarbonate or ammonium bicarbonate are added, and any method of addition can be adopted.

However, the method of adding an aqueous solution of a tin compound to an aqueous solution of an alkali metal bicarbonate or an ammonium bicarbonate is
This method is preferable because a uniform gel can be obtained and the gel washing operation in the next step can be carried out efficiently.

Furthermore, the temperature during the gel formation reaction may be room temperature;
There is no need to perform operations such as cooling.

The gel thus produced is then washed to remove impurities. Regarding the amount of residual impurities, it is preferable not to interfere with the production of crystalline tin oxide/antimony sol and for various purposes. However, only ammonia remains in the gel when ammonium bicarbonate is used to produce the gel. There is no harm in doing so.

The cleaning means is not particularly limited, and any commonly used methods such as water filtration and repulp centrifugation can be used.

Further, a method of removing impurities by contacting with a suitable ion exchanger or the like may also be adopted.

Niantimony dioxide and ammonia are then added to the washed gel.

The amount of diantimony trioxide added is such that the molar ratio of antimony to tin contained in the gel is 0.3 as Sb/Sn.
Use as follows.

That is, when diantimony trioxide is used in an amount such that the Sb/Sn molar ratio is 0.3, it is difficult to obtain crystalline tin oxide antimony sol as a single composition even if it is subjected to the treatment steps described below. Therefore, unreacted diantimony trioxide remains, which is not preferable.

Although there is no particular limitation on the lower limit of the Sb/Sn molar ratio, for example, when the crystalline tin oxide antimony sol obtained by the method of the present invention is used as a transparent conductive material,
If the Sb/Sn molar ratio is below 0.005, the electrical conductivity will drop significantly, which is not preferred in practice.

As for the diantimony dioxide of the present invention, in addition to the commonly used anhydride, its hydrate called antimonic acid can also be used.

Next, regarding the amount of ammonia added, the pH of the gel
A suitable amount is sufficient to bring the range of 8 to 12, preferably 9 to 11.

In other words, if PI (deviates from the above range, a sol with excellent dispersibility cannot be obtained. In this case, the necessary amount of ammonia to be added depends on the amount and type of trace impurities remaining in the gel, or the amount of 5 nOe in the gel, Although it varies depending on the concentration of sb, it is generally in the range of 0.05 to 1.00 mol per 1 mol of 5nOe.

Next, water is added to the pH-adjusted gel to adjust the concentration, if necessary.

In this case, it is desirable that the 5n02 concentration be 15% or less. If the concentration exceeds this, the resulting sol will not only be extremely viscous and extremely difficult to handle, but will also be non-uniform.

The gel with adjusted pH and concentration is then subjected to hydrothermal treatment. This treatment produces a crystalline tin oxide antimony sol with a particle size of 300X or less.

Regarding the conditions of hydrothermal treatment, the treatment temperature is generally high, <,
Furthermore, the longer the treatment time, the better the development of crystal form, and the production of colloidal particles with larger particle sizes.

For example, in order to produce a sol consisting of colloidal particles with a particle size of approximately 80°, hydrothermal treatment at 200° C. for 6 hours is required. 1 yen, the crystalline tin oxide/antimony sol can be manufactured with the optimum particle size according to each application, and the point is that it can be controlled by selecting the hydrothermal treatment conditions.
This is a major feature of the present invention.

Note that the hydrothermal treatment is preferably carried out under stirring; if the treatment is carried out without stirring, the added nantimony dioxide may settle at the bottom of the autoclave, resulting in a non-uniform sol.

The crystalline tin oxide/antimony sol obtained by the method of the present invention is a sol with a particle size of 300X or less in which sb and Sn are dissolved in solid solution at an Sb/Sn molar ratio of 0.3 or less.

Therefore, it is not only very useful as a transparent conductive material, but also useful in the field of electroceramics, such as gas sensor materials.
It can be applied to many other uses.

For example, conductive materials can be used for solar cells, EL elements, liquid crystal elements, transparent electrodes of transparent switches, etc., prevention of static electricity on display surfaces such as CRTs, prevention of electromagnetic interference caused by microwaves, promotion of electrical conductivity in discharge tubes, automobiles, aircraft, etc. It can be used to prevent fogging of windows of appliances, transparent heating elements, thin film resistors, surface treatment for electroless plating, and to prevent static electricity on glass fibers.

Furthermore, it can also be used as a conductive powder coated with an inorganic filler such as calcium carbonate or silica, but is not limited thereto.

(Example) The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

Moreover, unless otherwise specified, all percentages indicate weight percent.

Example 1 1000 parts of stannic chloride aqueous solution (SnOe 17.6%) was added to ammonium bicarbonate aqueous solution (N) 133.0%) 3
The solution was gradually added to 442 parts while stirring to form a gel. The pH of the gel solution at this time was 7.2.

The generated gel was filtered, about 1000 parts of water was added thereto, repulped and mixed, and solid-liquid separated using a centrifuge.
This operation was repeated until no chlorine was observed in the gel, and as a result, 5nOe was 36.6%, N)l.

A gel containing 0.62% was obtained.

Next, diantimony trioxide (Sb) was added to 100 parts of this gel.
20.99%) 0.71 part, ammonia water (NH32,
0%) and 255 parts of water were added and mixed, and the pH was 9,
After forming the gel slurry in step 6, this was transferred to an autoclave and hydrothermally treated at 230°C for 4 hours while stirring.
A crystalline tin oxide antimony sol was obtained.

As a result of compositional analysis, this sol has 5nOelO, 0%, Sb
O, 16%, Sb/Sn molar ratio 0.02, and the particle diameter measured by transmission electron microscopy was 120A.

Furthermore, as a result of drying this sol at 100°C and performing X-ray diffraction measurements, the main peaks were [3.35λ, 2.64X,
1.77K, 2.37λ, and 1.68λ, the crystal form was identified as cassiterite, and no X-ray peak derived from antimony compounds was observed.

Furthermore, when one portion of this sol was allowed to stand at room temperature for one month, no sediment was observed, and the sol properties were maintained.

Example 2 A stannic sulfate aqueous solution (So102) was added to 5037 parts of a sodium bicarbonate aqueous solution (Na1.4%) with stirring.
1000 parts of 10°5%) were gradually added to form a gel.

The pH of the gel solution at this time was 7.6.

After filtering the generated gel, water injection filtration and cleaning were performed until sodium, chlorine, and sulfate radicals were no longer observed in the gel. As a result, a gel containing 23.7% of SnO□ was obtained.

Next, 100 parts of this gel was added with nioantimony dioxide (Sb
20399%) 7 parts, ammonia water (N) 1.1.5%
), and 134 parts of water were added and mixed, and the pH was 10.9.
After making a gel slurry, this was transferred to an autoclave and hydrothermally treated at 180°C for 10 hours while stirring.
A crystalline tin oxide antimony sol was obtained.

As a result of compositional analysis, this sol was found to be 5n027.0%, Sb1
．． 7%, and the Sb/Sn molar ratio was 0.30, and the particle diameter was measured to be 60% by transmission electron W4 microscopic observation.

Furthermore, as a result of drying this sol at 100°C and performing X-ray diffraction measurements, the crystal form was found to be cassiterite.
e), and no X-ray peak derived from an antimony compound was observed.

Further, when this sol was allowed to stand at room temperature for one month, no sediment was observed, and the sol properties were maintained.

Claims (1)

[Claims] After producing a gel by reacting a tin compound with an alkali metal bicarbonate or ammonium bicarbonate,
A method for producing a crystalline tin oxide/antimony sol, which comprises adding diantimony trioxide and ammonia and subjecting it to hydrothermal treatment.