JPS6110029A - Preparation of electrically conductive stannic oxide - Google Patents

Abstract

PURPOSE:To obtain electrically conductive stannic oxide having excellent electrical conductivity and suitable as an antistatic agent for synthetic fiber, by dispersing antimony oxide in an aqueous solution of tartaric acid, mixing the dispersion with hydrated stannic oxide, and drying, pulverizing and calcining the mixture. CONSTITUTION:Antimony tartrate is produced by dispersing antimony oxide in an aqueous solution of tartaric acid. The amount of tartaric acid is >=0.01 equivalent per 1 equivalent of antimony. Hydrated stannic oxide is added to the dispersion, mixed thoroughly with a ball mill, etc., dried in a hot-air circulation drier, etc., pulverized with an impact pulverizer, and calcined with a calcination oven to obtain the objective electrically conductive stannic oxide wherein a part of Sn atoms of stannic oxide are substituted with Sb atoms. A product having excellent electrical conductivity can be produced without using the water-washing step, even at a calcination temperature of as low as <=1,000 deg.C, and accordingly, the compound can be obtained at a low cost with simple procedure.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides an industrial method for producing conductive tin oxide, which is used in antistatic agents for synthetic resins and fibers, chemical sensor elements, and conductive pastes. It is related to.

<Prior art> It is known that when some of the Sn atoms in tin oxide are replaced with sb atoms, conductivity develops and becomes conductive tin oxide. Antimony oxide (Sb,
03 or 5bzOs) and heated to about 1,300°C, or by neutralizing an alcohol mixed solution of tin chloride and antimony trichloride, the resulting coprecipitate was washed with water and then heated at 1,000 to 1,300°C. The production method involved decomposition.

<Problems to be solved by the invention> However, the former manufacturing method only involves mixing in the particle mixing region, and in order to diffuse sb atoms into the stannic oxide crystal, a high temperature of 1300°C is required. Requires.

If antimony oxide aggregates and remains due to insufficient mixing, there is a drawback that it is likely to melt at high temperatures and grow during the cooling process to form coarse particles. In addition, the latter production method has the disadvantage that washing with water to remove salts produced by neutralization is time consuming and inefficient.

However, if washing with water is insufficient, there is a concern that the particle size may increase due to the influence of salts.

In general, inexpensive materials can be used for the firing furnace if the firing temperature is below 1200°C, but in the conventional method described above,
Since the upper limit is 0°C, expensive materials must be used. Therefore, a comparatively simple manufacturing method in which the firing temperature is 1200° C. or lower, preferably 1000° C. or lower is desired industrially. Therefore, the present invention provides an industrial method for producing conductive tin oxide having excellent conductivity.

<Means for Solving the Problems> That is, the present invention involves dispersing antimony oxide in an aqueous tartaric acid solution, adding hydrous t8 oxide, mixing, drying, and pulverizing the resulting powder, which is then calcined, pulverized, or mixed. to obtain conductive tin oxide. According to the present invention, λq conductive stannic oxide tartaric acid is used, and the conductivity is better under the same conditions than without it.

The above hydrous stannic oxide is represented by SnO2.XH,O.

However, X satisfies 0.02<X<1.5. X≧
In the case of 1, it is sometimes referred to as β-ti acid. β in a narrow sense
-Stannic acid is H,,SnO,. On the other hand, as antimony oxide, any antimony oxide or antimony oxide hydrate can be used regardless of the composition.

<Operation> Next, the operation will be explained. When antimony oxide is dispersed in an aqueous tartaric acid solution, dissolution begins from the particle surface of the antimony oxide, producing antimony tartrate.

Antimony tartrate↓ Many compositional formulas are known.

For example, S b (OH) (C4HsOa) x 2H20
, or S b t O(C4Ha Ob ) t '
68 z O and the like.

Since all antimony tartrate dissolves in water, an antimony tartrate aqueous solution is formed in proportion to the amount of tartaric acid.

When the tartaric acid aqueous solution is heated to a high temperature, antimony tartrate is produced quickly, so a high temperature is preferable, but a room temperature is also acceptable.

The tartaric acid aqueous solution can be easily prepared by dissolving tartaric acid in water. The weight of tartaric acid is 0.01 equivalent or more, preferably 0.05 to 2.5 equivalents per equivalent of Sb.
Equivalence is preferred. The amount of water is preferably such that the mixture of antimony oxide and hydrated tin oxide is wetted. Naturally, if the mixture is hypertensive, use more water.

Typically, the amount of water required to wet the mixture of antimony oxide and hydrated tin oxide exceeds the minimum amount of water that will not dissolve the tartaric acid. According to the present invention, antimony oxide is added to an aqueous solution of tartaric acid, or the aqueous solution of tartaric acid is poured into the antimony oxide, and the mixture is thoroughly mixed and dispersed to produce antimony tartrate. Then, add hydrous stannic oxide and mix thoroughly. As a mixer, a universal mixer, a Raikai machine, a ball mill, etc. are useful. At this time, water may be added as appropriate while checking the wet state of the mixture. The mixing time can be selected arbitrarily. If there is unreacted tartaric acid with antimony oxide after mixing, it may react with hydrous stannic oxide in the next step or remain as tartaric acid. There is no worry that it will remain in the stannic oxide.

However, it is economically undesirable to use too much tartaric acid.

Conventional drying methods can be used to dry the above mixture. For example, as the dryer, a hot air circulation dryer, a vacuum dryer, etc. are used. As the pulverizer for pulverizing after drying, an impact pulverizer, friction pulverizer, jet pulverizer, etc. are used. When crushed, a pale yellow powder is obtained, and this pale yellow powder is placed in a firing pot and fired in a firing furnace. As the firing furnace, a gas firing furnace or an electric furnace is used. Firing temperature is 600
It is carried out at a temperature of -1200°C, preferably 800-1000°C.

The firing time is 15 minutes or more, preferably 30 minutes to 4 hours. The fired product becomes a gray-blue powder. This fired product is pulverized or mixed to obtain conductive tin oxide.

In the present invention, when tartaric acid is used, it is assumed that the dispersibility of antimony is improved and good diffusion of antimony occurs even when the firing temperature is low, and as a result, conductive tin oxide with excellent conductive performance is obtained. be done. The conductive performance of the conductive stannic oxide according to the present invention changes depending on the amount of antimony oxide and hydrous stannic oxide. This is S b /
Although this is thought to be due to the Sn ratio, satisfactory conductive performance was obtained with the conventionally known Sb/Sn ratio. More specifically, antimony oxide and hydrous stannic oxide are weighed and prepared so that the equivalent ratio S b /S n is in the range of 0.05 to 10%, preferably 1.5 to 5.0%. is desirable. When the S b /S n is less than 0.05%, the conductive performance is poor, and when it is more than 10%, it is wasted because it does not contribute to improving the conductive performance. However, the molecular weight of hydrous stannic oxide is not determined, so Sn
The content is determined by analysis. Similarly, the sb content of antimony oxide is determined by analysis and the amount to be charged is determined.

The conductive performance was evaluated by measuring the specific resistance by measuring the pressurized resistance of the sample.

However, R is the resistance value, and t is the thickness of the pressurized powder.

<Example 1> 215 g of antimony trioxide was added to a solution of 29 g of tartaric acid dissolved in 41 parts of water, and after stirring for 2 hours, 8270 g of β-stannic acid was dissolved.
g was added and mixed thoroughly. Here, the equivalent ratio of tartaric acid to Sbl equivalent is 0.131 (hereinafter referred to as tartaric acid/sb), and the equivalent ratio of sb to Snl equivalent is 0.131.
Below 03H, it is written as S b / S n. ). Then, the dried cake obtained by drying at 100° C. was pulverized using an impact pulverizer. The pulverized powder was put into a firing body and fired at 800°C for 2 hours in an electric furnace.

After cooling, mix with a mixer to obtain 7359 g of conductive tin oxide.
I got it. The specific resistance was 0.9Ω.

[Comparative Example 1] 7200 g of β-stannic acid and 18 antimony trioxide were placed in a mixer.
7 g was added and dry mixed for 2 hours. The mixed powder was placed in a firing body and fired at 800°C for 2 hours. After cooling, the mixture was mixed in a mixer to obtain 6520 g of conductive tin oxide.

The specific resistance was 4.1Ω. However, S b / S
n is 0.031.

[Comparative Example 2] After adding 93.5 g of antimony trioxide to water 21 and stirring for 2 hours, 3600 g of β-stannic acid was added and thoroughly mixed.

S ty /S n is 0.031. Thereafter, 3201 g of conductive tin oxide was obtained in the same manner as in Example 1.

The specific resistance was 2.4Ω.

It is clear that Example 1 has excellent conductive performance when compared with Comparative Example.

<Example 2> 58 g of antimony trioxide was added to a solution of 20 g of tartaric acid dissolved in water IIl, and the mixture was stirred for 2 hours. and β-stannic acid 22
After adding 42 g and thoroughly mixing, it was dried at 100°C.

Here, tartaric acid/Sb is 0.334 and Sb/Sn is 0.
．． It is 031. The obtained dry cake was pulverized using an impact pulverizer, then placed in a sintered body and sintered at 800° C. for 2 hours in an electric furnace. After cooling, conductive tin oxide 2 is mixed with a mixer.
023 g was obtained. The specific resistance was 1.0Ω.

<Example 3> 156 g of antimony trioxide was added to a solution in which 160 g of Tartar #1 was heated to about 50°C and dissolved in 51 parts of water, and the mixture was stirred for 3 hours. Then, 6000 g of β-stannic acid was added and thoroughly mixed, followed by drying at 100°C. Here, tartaric acid/Sb is 0.9
96 and S b /S n is 0.031. Hereinafter, 5350 g of conductive tin oxide was prepared in the same manner as in Example 2.
I got it. The specific resistance was 0.5Ωl.

<Example 4> 5120g of β-stannic acid was placed in a fired body and heated at 600℃1 in an electric furnace.
4500 g of hydrous tin oxide obtained by baking for 1.5 hours
g/N tartaric acid aqueous solution 3e and antimony trioxide 85g
and mixed thoroughly. Here tartaric acid/S
b is 0.051 and S b /S n is 0.02. Next, it was dried at 100°C, crushed, and then fired at 800°C for 2 hours. After cooling, pulverize to form conductive tin oxide 4
535 g was obtained. The specific resistance was 65Ω1.

Incidentally, when hydrous stannic oxide calcined at 600° C. was used instead of β-stannic acid, the specific resistance tended to increase, but the effect of tartaric acid was observed.

<Example 5> 112 g of antimony tetroxide was added to a solution of 14 g of tartaric acid dissolved in 2 Il of water, and the mixture was stirred for 2 hours. and β-stannic acid 4
200 g was added and mixed. Here tartaric acid/sb is 0
．． 255, and S b /S n is 0.015.

Next, it was dried at 100°C, crushed, and then fired at 1000°C for 2 hours. 3825 g of conductive tin oxide after cooling and crushing
I got it. The specific resistance was 1.7Ω.

<Effects of the Invention> As described above, the present invention uses tartaric acid in an amount of 0.01 equivalent or more relative to the Sbl equivalent, but compared to the case where tartaric acid is not used, conductive tin oxide with excellent conductive performance is can get. In addition, the present invention does not require a water washing process, and the firing temperature is 100%.
Since the conductive performance is good even when the temperature is 0° C. or lower, the process is relatively simple and it can be manufactured at low cost. Therefore, the present invention has great industrial utility value.

Claims (1)

[Claims] After dispersing antimony oxide in an aqueous tartaric acid solution using 0.01 equivalent or more of tartaric acid per equivalent of Sb,
A method for producing conductive tin oxide, which comprises adding and mixing hydrous tin oxide, drying, pulverizing, and firing.