JPS61122123A - Production of electrically conductive tin oxide fine powder - Google Patents

Abstract

PURPOSE:To produce the titled fine powder composed of antimony and tin oxide, having light color, and having excellent electrical conductivity, by dissolving tin chloride and antimony chloride in a carboxylic acid (or its aqueous solution), and pouring the solution into hot water to effect the hydrolysis of the chlorides. CONSTITUTION:50-1,500g/l of tin chloride and 0.054-332g/l of antimony chloride are dissolved in a carboxylic acid having a pH of <=6.5 (e.g. acetic acid, formic acid, etc.) or its aqueous solution, and the solution is poured into hot water to effect the hydrolysis of the chlorides, and precipitate fine powder having a composition composed of 0.1-20wt% antimony and the remaining part of tin oxide. The precipitate is separated by filtration, and calcined in air to obtain the objective electrically conductive tin oxide fine powder. The obtained tin oxide fine powder is especially suitable for coating or mixing to a plastic, silicone rubber, etc., to impart electrical conductivity to the plastic, etc.

Description

[Detailed Description of the Invention] Technical Field> The present invention has a color tone ranging from white to pale blue and has good conductivity, and is particularly applicable to plastics, silicone rubber, etc. (hereinafter collectively abbreviated as plastics). This invention relates to a method for producing conductive tin oxide fine powder, which is suitable for use in applying or mixing with other materials to impart electrical conductivity to them.

<Prior art> Conventionally, conductivity has been imparted to plastic by coating or mixing conductive powder such as metal powder or carbon powder into plastic. When carbon powder is mixed in, the color tone of the plastic itself is impaired, giving it a gray or blackish tone, making the color tone of the plastic quite limited, and furthermore impairing the inherent transparency of the plastic. As a result, its use had to be limited.

Therefore, for example, plastic coatings, sheets, plates, etc. that require conductivity and transparency, which have recently been widely used as display electrodes, protective films, antistatic 1L films, and transparent heating elements, etc. Various studies have been conducted on conductive fine powders that can be mixed into plastics to impart good conductivity to the plastics without impairing their transparency.

In these studies, tin oxide with solid solutions of antimony oxide, indium oxide, gallium oxide, bismuth oxide, etc. has been found to be useful because it has excellent conductivity and can form white to pale blue fine powder. It is.

Since the transparency and conductivity of tin oxide solid solutions depend primarily on the sinterability of the powder, many manufacturing methods have been investigated to obtain fine powders with high surface energy and excellent dispersibility. These manufacturing methods are: (1) preparing powders of tin oxide and antimony oxide, mixing and sintering; and (2) neutralizing tin oxide and antimony chloride in an alcohol solution to co-create tin oxide and antimony oxide in colloidal form. There is a method in which the colloidal coprecipitate is precipitated and then calcined (Japanese Patent Application Laid-open No. 51-5300).

The present applicant etc. also have ZnO, TiO2, 5n02
.

Al2O3, In2O3, 5i02, MgO, Ba
At least one crystalline metal oxide selected from O, MoO3, and fine particles of composite oxides thereof
No. 143430, JP-A-56-143431, etc.).

Among these, in particular, a solution consisting of a predetermined amount of tin chloride and antimony chloride dissolved in a mixture of one or more of alcohol, fa acid aqueous solution, and acetone is added to heated water. A manufacturing method (JP-A-56-156606) is known in which fine tin oxide powder is precipitated.

However, when using this manufacturing method, a considerable amount of residual ions remain in the tin oxide fine powder of the product.When dispersing tin oxide fine powder with a large amount of residual ions in a dispersion medium during use, the residual ions disperse the fine powder. There was a problem that the system was prone to agglomeration. On the other hand, if the number of washings is increased to remove residual ions, the yield deteriorates. In addition, according to this method, a fine powder with a particle size small enough to maintain sufficient transparency and conductivity even when applied to or mixed with plastics, but tin oxide fine powder with even better conductivity is produced. development is desired.

<Objective of the Invention> The object of the present invention is to improve the above points, and to dissolve and hydrolyze tin chloride and antimony chloride using an organic acid, particularly a carboxylic acid, or an aqueous solution thereof. It is an object of the present invention to provide a method for producing conductive tin oxide fine powder, which can yield fine tin oxide powder with very good properties.

<Brief Description of the Invention> Such objects can be achieved by the present invention described below.

That is, the present invention provides at least one solution having a pH of 13.5 or less.
50-1500g/seed carboxylic acid or its aqueous solution
By adding a solution of tin chloride and 0.054 to 332 g/l of antimony chloride to heated water, a composition containing 0.1 to 20% by weight of antimony, with the remainder essentially consisting of tin oxide. The present invention provides a method for producing conductive tin oxide fine powder, which is characterized by precipitating and producing fine powder of conductive tin oxide.

As the carboxylic acid, it is preferable to use acetic acid, formic acid, or a mixture thereof.

<Specific Structure of the Invention> The method for producing the conductive tin oxide fine powder of the present invention will be described in detail below.

(1) First, a carboxylic acid solution containing tin chloride and antimony chloride with the above-mentioned predetermined concentrations is prepared.

Particularly suitable carboxylic acids are acetic acid and formic acid.

The carboxylic acid or carboxylic acid aqueous solution that dissolves tin oxide and antimony chloride has a pH of 6.5 or less.

This is because if the pH of this solution exceeds 6.5, hydrolysis occurs and precipitates are formed, making it impossible to control the particle size of the precipitates.

1. of tin chloride and antimony chloride dissolved in this carboxylic acid or carboxylic acid aqueous solution. The reason for limiting (as in H) is as follows.

(a) Sr+C:14 content in solution If the content is less than 50 g/1, substantially 5nC1
If the content of 4 is too small, the precipitation rate of 5n02 fine powder due to hydrolysis will be slow, requiring a long processing time, and the amount of acid per unit amount of 5n02 will be large, making it uneconomical. This further deteriorates the cleanability. On the other hand 1
If the content exceeds 500 g/fL, the viscosity of the liquid increases, making it difficult to process and making it impossible to obtain fine powder with a uniform particle size. Therefore, the content of 5nC1a is 50 to 150 g/fL.
0g/4 is good.

(b) SbG+3 content in the solution In the relative relationship with 5nC14, the content is 0.0
At less than 54 gin, sb-containing 5n02 that precipitates
If the sb content in the fine powder becomes less than 0.1% by weight, and on the other hand exceeds 332 g/l, the sb content in the sb-containing 5n02 fine powder exceeds 20% by weight. Since it becomes high, its content is 0.054 to 3
32g/fL is good.

(2) Next, add the solution created in (1) to heated water,
A fine powder containing 0.1 to 20% by weight of antimony and the remainder substantially consisting of tin oxide is precipitated.

The reason for limiting the sb content in the sb-containing 5n02 fine powder as described above is as follows.

If the sb content is less than 0.1% by weight, the desired good conductivity cannot be ensured, while if the content exceeds 20% by weight, the white or pale blue color of the powder will be lost and the powder will have a bluish tinge. The content is preferably 0.1 to 20% by weight because the color tone and transparency of plastics are impaired when they are coated or mixed into plastics.

(3) Next, the sb-containing 5n02 powder obtained in (2) is filtered, and after drying, it is fired in air for the purpose of improving crystallinity, thereby producing a conductive tin oxide fine powder containing sb. .

Table 1 shows the tin oxide fine powder produced by the production method of the present invention.
As shown in the figure, the ionic conductivity of the cleaning solution is 10iσcm-
1 of the following fine tin oxide powder produced by the conventional method:
It is smaller than 0 m0.Cl1l-', which means that the tin oxide fine powder produced by the method of the present invention has less residual ions than the tin oxide fine powder produced by the conventional method.

Furthermore, the tin oxide fine powder produced by the method of the present invention has a smaller volume resistance after firing than the tin oxide fine powder produced by the conventional method.

Note that the primary particle size of tin oxide produced by the production method of the present invention is slightly larger than that obtained by the conventional method by X-ray measurement, but the secondary particle size is ``slightly larger than that obtained by the conventional method.'' It remains unchanged at about 0.3 grn and has excellent transparency.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples of the present invention.

(Example 1) Sr+C: +4 a5H20 (76% as 5nC14
) 113.7g and 5bC13 (SbCl:+9
7%) lo, 7g to 150cc (7) Acetic acid (pH
1,0 or less), and this solution was added to 90°C water at a temperature of 3,000 °C.
cc for about 2 hours to perform hydrolysis. The precipitate-containing liquid obtained by this hydrolysis was filtered through a 50° filter paper, and the precipitate was separated by filtration.Then, the separated precipitate was dried, and then calcined at 500°C for 2 hours. The material was washed with pure water and dried to obtain fine tin oxide powder.

(Example 2) SnCI4 ・5H20 (containing 76% as SnC14) 113.7g,! -5bCI3 (97 SbC13
%) 10.7g to 300cc7) Gi#(p)l
x, o or less), and the Kono solution was added to 500 ml of water at 90°C.
Hydrolysis was carried out by injecting 0 cc over about 2 hours. The precipitate-containing liquid obtained by this hydrolysis was filtered through a 50°C filter paper, and the precipitate was separated by filtration.The separated precipitate was then dried and calcined at 500'C for 2 hours to obtain a The fired product was washed with pure water and dried to obtain fine tin oxide powder.

(Example 3) SnC14.5H20 (containing 76% as Sr+C14) 113.7g 5b (It3 (97% SbC13)
(Contains) IQ, 7g is dissolved in a mixture of 150cc of acetic acid and 30cc of pure water (pH 1.0 or less), and this solution is
Hydrolysis was carried out by pouring into 2000 cc of water at 0°C for about 1 hour.

The precipitate-containing liquid obtained by this hydrolysis was filtered through a 50° filter paper, and the precipitate was separated by filtration.Then, the separated precipitate was dried, and then calcined at 500°C for 2 hours. The material was washed with pure water and dried to obtain fine tin oxide powder.

As shown in Table 1, the tin oxide fine powder obtained in Example 1 of the present invention has a primary particle size measured by xm that is slightly larger than that of the comparative example tin oxide fine powder. The secondary particle size is the same as that of the tin oxide fine powder of the comparative example.Furthermore, the tin oxide fine powder obtained by the example of the present invention is different from the tin oxide fine powder of the comparative example. The conductivity is significantly improved compared to the previous one.

(Comparative example) 113.7 g of SnC14* 5H20 (containing 76% as SnC14) and 5bC13 (containing 97% SbCl2)
Containing) 10.7g was dissolved in 6N 300cc hydrochloric acid,
This solution was poured into 5000 cc of water at 90° C. for about 2 hours to perform hydrolysis, and the same procedure as in the above Example was carried out to obtain fine tin oxide powder.

Regarding the tin oxide fine powder obtained in the above Examples and Comparative Examples, 1 volume resistance, ionic conductivity of cleaning liquid, and X after firing.
The linear particle size was measured. The results are summarized in Table 1.

In addition, measurements of the various properties described in Section 7 were performed as follows.

(1) Volume Resistance Finely powdered tin oxide is placed in a cylinder with a diameter of 10 aug, and after applying a pressure of 1 ton/cs2, its resistance is measured, and the volume resistance is determined from the measured value.

(2) Ionic conductivity of cleaning liquid The obtained finely powdered tin oxide is washed to remove impurities.

In this cleaning method, 20 g of fine tin oxide powder is mixed with 150 c of pure water.
c and stir with a stirrer.

After the tin oxide has precipitated, the supernatant liquid is discarded. This operation was repeated several times. The ionic conductivity of the cleaning solution in Table 1 was measured after adding pure water and stirring the first time.

(3) Particle size of tin oxide fine powder Particle size is calculated from the half width of each peak using a powder diffractometer.

<Effects of the Invention> According to the production method of the present invention, by dissolving tin chloride and antimony chloride with carboxylic acid, fine tin oxide powder with good conductivity can be obtained while maintaining transparency and having a volume resistance as low as 40%. .

Furthermore, according to the production method of the present invention, the amount of ions remaining in the obtained tin oxide fine powder is small, and therefore, residual ions can be effectively washed, so the yield of fine powder can be increased. .

In particular, the effects of the present invention are remarkable when acetic acid and/or formic acid is used as the carboxylic acid.

Procedural amendment (own ship? 0 Name of the invention Method for manufacturing conductive tin oxide fine powder 3, Person making the amendment, Relationship to the case Patent applicant address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (520) Fuji Photo Film Co., Ltd. 4, agent
101 Telephone: 864-4498 Address: 3-2-2-6 Iwamoto-cho, Chiyoda-ku, Tokyo Contents of the amendment (1) On page 3, line 15 of the specification section, “antimony alcohol” has been replaced with “antimony alcohol”. "Alcohol," he corrected.

(2) Insert "wo" after "alcohol solution" on page 3, line 15 of the specification section.

(3) "Tin oxide and" on page 6, line 13 of the specification ring,
Correct as “tin chloride and”.

(4) In the specification section 11, from the second line to the third line, "2000 ccJ of water at 90°C is corrected to 3000 ccJ of water at 90°C."

Claims (2)

[Claims] (1) Add 50 to 1500 g/l of tin chloride to at least one carboxylic acid or its aqueous solution with a pH of 6.5 or lower and
．． 0.054 to 332 g/l of antimony chloride was added to heated water.
1. A method for producing conductive tin oxide fine powder, which comprises precipitating and producing a fine powder containing 1 to 20% by weight of tin oxide, with the remainder substantially consisting of tin oxide. (2) The method for producing conductive tin oxide fine powder according to claim 1, wherein the carboxylic acid is acetic acid and/or formic acid.