JPH026332A - Production of indium oxide-tim oxide powder - Google Patents

Abstract

PURPOSE:To obtain indium oxide-tin oxide(ITO) powder having high sintering density and mechanical strength and enabling formation of ITO sintered compact by dispersing a mixed hydroxide of In and Sn into an organic solvent and subjecting the solvent to azeotropic dehydration and drying and calcining the residual material. CONSTITUTION:A precipitant such as ammonia is added to the mixed water solution of water soluble indium salt such as indium nitrate with water soluble tin salt such as tin sulfate to subject the mixed hydroxide to coprecipitation (molar ratio of Sn:In is preferably 5-15mol%). The mixed hydroxide is dispersed into an organic solvent such as n-butanol and the solvent is distilled to dehydrate the hydroxide and afford an amorphous oxide hydrate. Then the oxide hydrate is dried at 50-150 deg.C under pressure and calcined at 350-800 deg.C, preferably 400-600 deg.C to provide indium oxide-tin oxide(ITO) powder.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing indium oxide-tin oxide (hereinafter referred to as ITO) powder, and more specifically, a method for producing ITO powder having uniform and fine primary particles. It is related to.

The present invention can be used as a raw material for an ITO target used when creating a transparent conductive film by the sputtering method, and as a raw material for an ITO target used when creating a transparent conductive film by the coating method.
Our company provides a method for producing ITO powder, which is extremely suitable as a raw material for paints.

[Conventional technology]

In recent years, there has been a rapid increase in demand for ITO thin films as transparent conductive films used in solar cells, liquid crystal displays (-) and touch panels, etc. These ITO thin films are mainly produced by sputtering from ITO targets to glass and PET.
It is formed on a film.

Conventionally, ITO targets are produced by: (1) ITO powder obtained by mixing hydroxides of indium and tin after calcination; and (2) calcination of a mixed hydroxide of indium and tin prepared by a coprecipitation method. 1 q of ITO powder
(3) By thermally decomposing a mixed organic acid salt of indium and tin, 1
Qda ITO powder (Japanese Patent Application Laid-open No. 186416/1986) It is produced by pressure molding a head and then firing it. However, the ITO powder obtained by either method has a primary particle size of about 0.1 μm, and the ITO target produced using these 1TO powders has a sintered density of about 65% of the theoretical density (~4.5 μm). 6 'J/cttl)
However, this was not achieved and the product was extremely fragile. Targets with such low strength tend to crack during sputtering, which poses a serious problem in the continuous operation of thin film production.

In addition, by applying these ITO powders, ITO
It is also possible to form a j9 film. However, with conventional ITO powder, the ITO particles are not fine, so the transparency is particularly poor.
However, only an insufficiently thin film was obtained.

(Problems to be Solved by the Invention) An object of the present invention is to make it possible to form an ITO sintered body with extremely high sintering density and high mechanical strength, and to make it possible to form an ITO sintered body with very high sintering density and high mechanical strength.
The present invention provides a method for producing ITO powder consisting of uniform and fine primary particles, which forms R tFJ with extremely excellent transparency.

[Means for Solving the Problems] The present inventors have developed a method for solving the problems by producing a 100 ml particle having a uniform and fine primary particle size.
As a result of intensive studies on the production of ITO powder, we found that extremely uniform and fine ITO powder was produced by dispersing a mixed hydroxide of indium and tin in an organic solvent, azeotropically dehydrating it, drying it and then calcining it. This work led to the completion of the present invention.

From this powder, it is possible to produce 1 q of a sintered body with extremely high sintering density, and in addition, from the powder paint obtained by crushing this powder to 1 q, it is possible to form a coating film with extremely excellent transparency. .

In the present invention, there are no particular restrictions on the mixed hydroxide of indium and tin used as a starting material, but it has a uniform composition in order to obtain powders that are the raw materials for 11-0 targets 1 to 1 and ITO coating 1. This is desirable. Such a mixed hydroxide can be prepared, for example, by adding a precipitant to a mixed solution of a water-soluble indium salt such as indium nitrate, 5Am indium or indium chloride and a water-soluble tin salt such as tin nitrate, tin sulfate or tin chloride. It can be obtained by co-precipitating hydroxide and separating it in a furnace. At this time, any precipitant may be added as long as it can form a hydroxide precipitate, but it is preferable to use a precipitant that does not contain metal elements, such as an[nia].

In order to obtain ITO powder with low specific resistance, the proportion of tin to indium in the mixed hydroxide is preferably 3 to 25 mol%, more preferably 5 to 15 mol%.
Desirably, it is sil%. In the present invention, the mixed hydroxide of indium and tin obtained by the above method is dispersed in an organic solvent, and the mixed solution is distilled to dehydrate the hydroxide. A slushy oxide hydrate is obtained. At this time, when producing a sintered body, such as when using it as a raw material for Targera 1~, it is not necessary to carry out the distillation until the water in the solution is completely dehydrated. However, when a particularly fine powder is required, such as when used as a raw material powder for ITO paint, it is preferable to carry out the distillation until the water in the solution is dehydrated as completely as possible.

The organic solvent used during distillation may be one that can be azeotropically dehydrated with water, such as bempine.

1-1, xylene, alcohol having 10 or less carbon atoms,
Organic acids such as edyl benzoate can be mentioned, and one or more of these can be used. The distillation temperature at this time is usually 60'C or higher and up to the boiling point of the solvent.

Particularly when the powder is used as a raw material powder for paint, it is preferable to carry out distillation to the boiling point of the solvent.

The 1q oxide hydrate can be recovered by a method such as scraping or spray drying.

Next, the oxide hydrate obtained by azeotropic dehydration is dried, and this drying can be carried out at a temperature in the range of 50°C to 150°C. Furthermore, it is more efficient if the reaction is carried out under reduced pressure.

If the temperature of calcination after drying is high, 1q of ITO
350 to 80, as there is a risk of powder agglomeration.
It is preferable to carry out the calcination at 0'C, and the more preferable calcination temperature is 400 to 600C.

When using the ITO powder obtained as described above as a raw material for an I-'0 target, is it possible to use it as is or to obtain a sintered body with a high sintering density?
This powder can be used by pulverizing it by a general method such as a ball mill.

When used as a raw material for ITO coating, it can be dispersed in a solvent by wet pulverization using Paignton 1-force or the like.

〔Example〕

Hereinafter, the present invention will be explained based on examples, but the present invention is not limited to these in any way.

FIG. 1 shows a diagram for implementing the present invention. - An example of this is shown, and this embodiment will be explained based on this example.

Example 1 Metallic indium was dissolved in 60% nitric acid aqueous solution to 1.0
mol#! Stannous sulfate was dissolved in the solution prepared as follows to obtain a mixed aqueous solution of indium and tin (1). The aqueous solution (1) had a tin to indium ratio of 10%.

Add 1 as a precipitant (2) to the mixed aqueous solution (1) under stirring.
Add 4% ammonia water dropwise until the pH becomes 6, and add a mixture of indium and tin hydroxide precipitate vi(3) to j″1.

200 g of the hydrous hydroxide precipitate was decantated (4
) and dispersed in a sol state (5) in about 41 parts of n-butanol.
Shita. During the azeotropy of water and butanol, the temperature of the solution is 92°C.
Perhaps due to this, the liquid temperature gradually rises as dehydration progresses.
When the temperature reached °C, steaming 6) was stopped and the mixture was allowed to cool.

The earth-like oxide hydrate is separated by furnace,
This was dried under reduced pressure at a temperature of 90-100°C. After drying, it was calcined at 500'C (7) and crushed in a ball mill for 20 hours to obtain ITO powder (8).

When this powder was scanned 1 m by SEM, the -order particle size was 0.0
It was 5 μm.

Furthermore, when this powder was pelletized at a CIP pressure of 2 tons/cn and fired at 1300°C, the sintered density was 6.0.
It was possible to obtain ITO pellets of g/cIll.

Example 2 1 q of ITO powder was prepared in the same manner as in Example 1, except that stannous chloride was used instead of stannous sulfate to prepare an n-aqueous solution.

When this powder was observed by SEX, the -order particle size was 0.0
It was 5 μm.

Furthermore, this powder was pelletized at a CIP pressure of 2tOn/CIi and fired at 1300°C, resulting in a sintered density of 5.
An ITO pellet of 5', j/cI11 could be obtained.

Example 3 ITO powder was prepared in the same manner as in Example 1, except that stannous chloride was used instead of stannous sulfate to prepare a mixed aqueous solution.

When this powder was observed with SEM, the -order particle size was 0.0
It was 5 μm.

Furthermore, when this powder was pelletized with CIP pressure 2tOn/c scraps and fired at 1300°C, the sintered density was 6.0.
g/cI! It is possible to raise the ITO level of 1 by 1.

Example 4 ITO powder was obtained in the same manner as in Example 1 except that isoamyl alcohol was used as the IJUM solvent. When this powder was observed with SEM, the secondary particle size was 0.05 μm.
Met.

Furthermore, when this powder was pelletized at a CIP pressure of 2 tOn/cm and fired at 1300'C, the sintered density was 5.7.
9/cf11 11-0 pellets)! I can do this.

Comparative Example 1 A mixed hydroxide of indium and tin (3) obtained in the same manner as in Example 1 was dried for 500 ml without performing the step of dispersion and azeotropic dehydration in fJ solvent (5H6). The ITO powder was calcined at 1°C (7°C) and dissolved in a Sibor mill for 20 hours.

When this powder was observed with SEM, the -order particle size was 0.1
It was ~0.2μ.

Furthermore, this powder was subjected to a CIP pressure of 2 tons in the same manner as in Example 1.
When pellets 1~ were molded with a density of 4.0!7/cm and fired at 1300°C, ITO pellets 1~ with a density of 4.0!7/cm were obtained.

Example 5 ITO powder was obtained in the same manner as in Example 1, except that azeotropic dehydration was performed until the liquid temperature reached the boiling point of n-butanol.

Using this powder as a solvent, methyl-[Burg'! Using zirconia beads in the media, pulverization was carried out for 30 hours using force from Payne 1 to 1 to disperse the material, thereby obtaining an ITo powder. Use this to coat on PET film [2 μm by method]
An ITO thin film with a thickness of 1.5 m was prepared and the light transmittance at 700 nm was measured, and it was found to be 95% thick.

Comparative Example 2 1 q of indium and tin mixed hydroxide (3) prepared in the same manner as in Example 1 was dried without performing steps (5) and (6) of dispersing and azeotropically dehydrating it in an organic solvent. After 500'C
An ITO paint was applied in the same manner as in Example 4, except for the calcination (7).Using this, a 2μm single OR film was prepared on PET film-L by the 1b method, and it was coated at 700nm. When the light transmittance was measured, it was 60%.

(Effects of the Invention) As described above, according to the present invention, primary particles are uniform and fine.
Since it is possible to produce 1 q of ITO powder, this ITO
If powder is used, a sintered body with high sintering density can be obtained. Therefore, this makes it difficult for cracks to occur during sputtering, and it can withstand continuous operation! : ITO target 1~ or 1q
It will be done. Furthermore, by using this I-0 powder, it is possible to obtain an ITO paint with excellent transparency.

[Brief explanation of the drawing]

FIG.
Give an example. 1... Mixed aqueous solution of indium and tin 2... Precipitating agent 3... Mixed hydroxide precipitation of indium and tin 4...
Decantation 5...Dispersion in organic solvent 6...Azeotropic distillation 7...Calcination 8...ITO powder 1st EI Decantation (4) Dispersion in organic solvent (5)

Claims (1)

[Claims] (1) A mixed hydroxide of indium and tin is dispersed in an organic solvent, and then the mixed solution is azeotropically dehydrated, and then dried and
A method for producing indium oxide-tin oxide powder, which comprises calcining.