WO2017183849A1

WO2017183849A1 - Method for producing, from ito scrap, ito powder particle shape of which can be changed

Info

Publication number: WO2017183849A1
Application number: PCT/KR2017/003950
Authority: WO
Inventors: 이재용; 송상현; 김병준
Original assignee: (주)한청알에프
Priority date: 2016-04-18
Filing date: 2017-04-12
Publication date: 2017-10-26
Also published as: KR101730143B1

Abstract

The present invention relates to a method for recovering an ITO powder from ITO scrap such that the particle shape of the ITO powder can be changed. According to the present invention, an aqueous solution of indium chloride and tin chloride obtained by dissolving ITO in hydrochloric acid is used as a starting material for producing an indium-tin oxide powder, and the indium and tin contained in the aqueous solution are coprecipitated by adding a precipitant and a dispersant into the aqueous solution. Thereafter, the coprecipitated indium and tin hydrates are filtered and dried, and then the dried indium and tin hydroxides are fired, thereby obtaining an indium-tin oxide powder having spherical particles.

Description

Method for preparing ITO powder with control of particle form from waste ITO scrap

The present invention relates to a method for producing ITO powder that can control the particle form from waste indium tin oxide scrap (Indium tin oxide scrap).

Indium tin oxide (ITO) or tin-doped indium oxide refers to a solid solution compound in which tin oxide (SnO ₂ ) is added to indium oxide (In ₂ O ₃ ). It has a specific gravity of about 90% In ₂ O ₃ and about 10% SnO ₂ . This ITO thin film has a large bandgap energy of 3.55 to 3.75 eV and shows high light transmittance of 85% or more in the visible light wavelength range. In addition, in the case of In ₂ O ₃ without the addition of Sn ⁴ ⁺ ions, oxygen vacancies are generated in the non-stoichiometric composition In ₂ O ₃ _-x , and when Sn ⁴⁺ ions are added, due to the generated ^10-has been widely used such as flat panel displays, solar cells, electrochromic display elements as an optical material because of ⁴ Ω * indicate the n- type conductivity having a current density of ㎝. In addition, since the plasma frequency (w _P ) of the conduction electrons of ITO corresponds to the wavelength range of the IR region, it also shows reflection characteristics of electromagnetic waves in this region, and thus is applied as a heat reflection or an electromagnetic shielding device. have.

As such, ITO, which is used as a transparent electrode or the like for various IT products and smart devices, is mainly used as a sputtering target, and the use efficiency of such a target is very low at about 30%, so that a large amount remains after the process. In addition, since most of the materials are made of expensive indium metal, the method of recovering the waste ITO scrap left after use and recycling it to a new ITO target is very important in terms of cost reduction.

Looking at the conventional method for recovering the ITO powder from the waste ITO target, in Korean Patent No. 10-0177881, after preparing the IO powder, by mixing the TO powder (first method), and through the precipitation method, Disclosed are a method (second method) in which In and Sn hydrates are made and heat-treated to obtain an oxide simultaneously. In the case of the first method, since the two powders are mixed to prepare the IO and the TO separately, the homogeneity is inferior. The second method has the advantage that the powder does not need to be mixed separately, but in this case, Sn (NH ₄ ) ₃ Cl, which is produced as a byproduct during the neutralization reaction, remains in the powder even after the heat treatment, causing a decrease in density of the sintered compact.

Korean Patent No. 10-0322749 is the same as the precipitation method, but discloses a method of increasing the density of the sintered compact by preventing the formation of Sn (NH ₄ ) ₃ Cl by dropping the acid into the buffer base solution, powder It is not disclosed how to control the particle shape of the.

Therefore, in the present invention, while simultaneously obtaining In and Sn, to dissolve the waste ITO scrap with an acid in order to control the ITO to spherical particles, it is added dropwise to the alkaline solution to add a dispersant during the neutralization reaction, solving the above problems It has been found that the present invention has been completed based on this.

Accordingly, one aspect of the present invention is to provide a method for producing ITO powder that can control the particle form from waste ITO scrap.

According to one embodiment of the present invention, a method for preparing ITO powder having control of particle form from waste ITO scrap is:

a) providing an acid solution in which waste ITO scrap is dissolved in acid;

b) stirring the acid solution while maintaining the pH in a predetermined range while dropping the alkaline solution containing a dispersant;

c) filtering and drying the precipitate obtained from the reaction mixture of step b); And

d) calcining the dried precipitate in step c) to obtain ITO powder.

According to another embodiment of the present invention, the pH of step b) is maintained at 8 to 10.

According to another preferred embodiment of the present invention, the dispersant is at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, oleylamine, and polyvinylpyrrolidone.

In one embodiment, the amount of the dispersant used is in the range of 0.05 to 0.3% by weight based on the alkaline solution.

In another embodiment, the concentration of the solution of the waste ITO scrap in acid is 0.1 mol / L to 2.0 mol / L.

In another embodiment, the injection rate for dropping the acid solution into the alkaline solution is 10 ml to 50 ml per minute.

In another embodiment, the alkaline component is NaOH, NH ₄ OH, NH ₄ HCO ₃ , or CH ₃ COONH ₄ .

In yet another embodiment, in step d), the firing is carried out at 300 to 900 ° C.

The method according to an embodiment of the present invention may control the shape of the powder particles without generating Sn (NH ₄ ) ₃ Cl. This is expected to be applicable in fields where the particle form of the powder is important.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

1 is a process diagram schematically showing a method for producing spherical ITO powder according to one embodiment of the present invention.

Figure 2 is a SEM photograph of the ITO powder prepared according to the method of Example 1.

Figure 3 is a SEM photograph of the ITO powder prepared according to the method of Example 2.

Figure 4 is a SEM photograph of the ITO powder prepared according to the method of Comparative Example 1.

5 is a SEM photograph of ITO powder prepared according to the method of Comparative Example 2.

6 is a SEM photograph of ITO powder prepared according to the method of Comparative Example 3.

Before describing the invention in more detail, the terms or words used in the specification and claims are not to be limited to their usual or dictionary meanings, and the concept of terms is appropriately described to best explain the invention. It should be interpreted as meanings and concepts in accordance with the technical spirit of the present invention based on the principle that it can be defined. Therefore, the configuration of the embodiments described herein is only one preferred example of the present invention, and does not represent all of the technical idea of the present invention, various equivalents and modifications that can replace them at the time of the present application are It should be understood that there may be.

Hereinafter, preferred embodiments of the present invention will be described in detail so that those skilled in the art may easily implement the present invention. In addition, in describing the present invention, detailed descriptions of related well-known techniques that may unnecessarily obscure the subject matter of the present invention will be omitted.

As described above, one embodiment of the present invention is a method of obtaining an ITO powder having a spherical form by using an acid aqueous solution of waste ITO scrap as a raw material at room temperature and normal pressure, and dropping it into an alkaline solution to include a dispersing agent during the neutralization reaction. Related to

Referring to FIG. 1, a method for preparing ITO powder by recovering waste ITO scrap (hereinafter also referred to as "ITO target") according to the present invention is first referred to as an aqueous acid solution of an appropriate concentration of ITO scrap (hereinafter referred to as "acid solution"). Prepare. Specifically, an ITO target solution (In-Sn solution) is prepared by dissolving the waste ITO target using an acid capable of completely dissolving the waste ITO scrap maintaining a constant composition ratio between In and Sn. The acid is not particularly limited, but hydrochloric acid, nitric acid, sulfuric acid, or the like is used.

Separately, an alkali solution as a precipitant is prepared by dissolving a base that generates an OH- group in an aqueous solution in distilled water. In this case, a dispersant may be optionally added to the alkaline solution. The pH of the alkaline solution is preferably 11 to 13, and examples of the alkali component include NaOH, NH ₄ OH, NH ₄ HCO ₃ , or CH ₃ COONH ₄ . Among them, NH ₄ OH has an advantage that NH ₄ Cl, which is an intermediate product produced after the neutralization reaction, is easily dissolved in water, is easy to wash, and has no smell. However, a separate process may be required to remove Na ⁺ ions.

Subsequently, an acid solution in which the ITO scrap is dissolved is added dropwise to the alkaline solution containing the dispersant at a constant rate to react. According to an embodiment, while the two solutions are well mixed, the ITO precursor powder may be recovered by neutralization of the two solutions, thereby recovering the ITO powder. Optionally, the dispersant may be added dropwise to the alkaline solution together with an aqueous solution of ITO acid without addition to the alkaline solution. At this time, the base content in the alkaline solution should be 4 to 6 mol compared to 1 mol of ITO in the waste ITO scrap should be able to completely precipitate the In and Sn.

The reaction can be represented, for example, by the following scheme 1 when the base is NH ₄ OH:

Scheme 1

InCl ₃ (aq) + SnCl ₄ (aq) + NH ₄ OH (aq) → In (OH) ₃ (s) + Sn (OH) ₄ (s) + NH ₄ Cl (aq)

Meanwhile, the concentration of the acid solution in which the waste ITO scrap is dissolved in acid ranges from 0.1 mol / L to 2.0 mol / L, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mol / L, and all ranges and sub-ranges therebetween. If the concentration of the acid solution is less than 0.1 mol / L, productivity is lowered, and if it exceeds 2 mol / L, it is not preferable because it is difficult to dissolve ITO scrap with acid.

In addition, the injection rate of dropping the acid solution of the waste ITO scrap into the alkaline solution is preferably 10ml to 50ml per minute. If the injection rate is less than 10ml per minute, the injection rate is too slow to grow the particles difficult to obtain nano-sized ITO particles, if the injection rate exceeds 50ml per minute it is difficult to mix the reaction solution in a homogeneous state is preferable Can not do it.

And, the firing temperature may be in the range of 300 to 900 ° C, for example, 300, 400, 500, 600, 700, 800, 900 ° C, and all ranges and sub-ranges therebetween. If the firing temperature is less than 300 ℃ InSn (OH) precipitate is difficult to convert to In ₂ O ₃ -SnO ₂ oxide, if the firing temperature exceeds 900 ℃ is not preferable because the growth of particles after firing occurs. These detailed conditions are described in Korean Patent No. 10-0322749, the entire contents of which are incorporated herein by reference.

On the other hand, according to another embodiment, the method for adjusting the particle shape of the ITO powder is when the dosage of the dispersant is adjusted in the above-described reaction process, and thus heat treatment of the resulting precursor, as the particle shape is different, the particles You can adjust the shape.

According to another preferred embodiment, the process of the present invention comprises the steps of: a) providing an acid solution in which waste ITO scrap is dissolved in acid; b) stirring the acid solution while maintaining the pH in a predetermined range while dropping the alkaline solution containing a dispersant; c) filtering and drying the precipitate obtained from the reaction mixture of step b); And d) calcining the resultant to obtain an ITO powder.

In step b) above, the pH can be in the range of 8 to 10, for example 8, 8.2, 8.5, 8.8, 9, 9.5, 9.8, 10, and all ranges and sub-ranges therebetween. If the pH range is outside the range of 8 to 10, that is, if the pH is less than 8, the precipitate formed by the neutralization reaction is not precipitated as the pH is lowered, and is finely dispersed in the washing water to pass through the filter paper. Filtration can be a problem, and if it exceeds pH 10, the size of the particles of the precipitated powder may be irregular, which is undesirable. For reference, the pH change of step b) is about 13 to 10 when it is high alkaline, and about 11 to about 7 when it is low alkaline.

The dispersing agent of step b) may be at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, oleylamine, and polyvinylpyrrolidone. The higher the dosage of the dispersant, the more spherical ITO powder can be obtained, for example, in the range of 0.05 to 0.3% by weight relative to the alkaline solution, for example, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 Spherical ITO powder can be obtained by adding the dispersant in all ranges or sub-ranges therebetween, such as% by weight and 0.1 to 0.2% by weight. If a small amount of the dispersant is added, for example, at 0.01 wt% or less, a non-uniform angular powder is obtained, and if it exceeds 3 wt%, the precipitate tends to gel, resulting in difficulty in washing.

While not wishing to be bound by theory, the dispersant is adsorbed in the form of a film on the surface of the precursor particles, acting as a 'frame' that leads to spherical growth during heat treatment, yielding ITO powder with a particle shape close to spherical. It is believed that you can.

The filtration step c) is preferably filtered by a filter press, centrifugation, vacuum filtration, decantation, or the like. It is preferable to advance drying at 60-130 degreeC for 16 to 24 hours.

The firing of step d) may be performed at a temperature of 300 to 900 ° C. for 1 to 3 hours to obtain a powder having a spherical particle shape.

According to the present invention, the spherical ITO powder can be obtained by adjusting the particle form of the powder.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The following examples are intended to illustrate the invention, the present invention is not limited by the following examples.

Example 1

0.1% by weight of polyvinyl alcohol was added to an aqueous 1.3 mol ammonia solution, 0.44 mol / L of ITO hydrochloric acid was added dropwise at an injection rate of 50 ml / min, and the pH of the mixed solution was adjusted to about 9, thereby adjusting In (OH). ₃ , a solution in which a precipitate of Sn (OH) ₄ was formed was prepared. The supernatant of the obtained precipitate was removed, filtered, and dried at about 80 ° C. for about 20 hours. The dried hydroxide was further heat treated at about 930 ° C. for about 2 hours to obtain ITO powder particles. As a result of observing the obtained particles with an electron microscope, spherical particles were obtained as shown in FIG.

Example 2

0.1 weight% of polyvinyl alcohol was added to 1.3 mol of ammonia aqueous solution, 0.17 mol / L of ITO hydrochloric acid solution was dripped at the injection rate of 30 ml / min, the pH of the solution was adjusted to about 9, and In (OH) ₃ , a solution in which a precipitate of Sn (OH) ₄ was formed was prepared. The supernatant of the obtained precipitate was removed, filtered, and dried at about 80 ° C. for about 20 hours. The dried powder was further heat treated at about 930 ° C. for about 2 hours to obtain ITO powder particles. As a result of observing the obtained particles with an electron microscope, spherical particles were obtained as shown in FIG. 3.

Comparative Example 1

0.1 weight% of polyvinyl alcohol was added to 1.3 mol of ammonia aqueous solution, 0.44 mol / L of ITO hydrochloric acid solution was dripped at the injection rate of 50 ml / min, the pH of the solution was adjusted to about 7, and In (OH) ₃ , a solution in which a precipitate of Sn (OH) ₄ was formed was prepared. The supernatant of the obtained precipitate was removed, filtered, and dried at about 80 ° C. for about 20 hours. The dried powder was further heat treated at about 930 ° C. for about 2 hours to obtain ITO powder particles. As a result of observing the obtained particles with an electron microscope, as shown in Fig. 4, particles having an angular shape were obtained.

Comparative Example 2

100 g / L of an aqueous solution of ITO hydrochloric acid was added dropwise to an aqueous solution of 1.3 mol of ammonia at an injection rate of 50 ml / min to adjust the pH of the solution to 9, and a solution of precipitates of In (OH) ₃ and Sn (OH) ₄ was formed. Was prepared. The supernatant liquid of the obtained precipitate was removed, and it filtered and dried at 80 degreeC for 16 to 24 hours. The dried powder was further heat-treated at 930 ° C. for 2 hours to obtain ITO powder particles. As a result of observing the obtained particles with an electron microscope, as shown in Fig. 5, particles having an angular shape were obtained.

Comparative Example 3

100 g / L of an aqueous solution of ITO hydrochloric acid was added dropwise to an aqueous solution of 1.3 mol of ammonia at an injection rate of 50 ml / min. The pH of the solution was adjusted to about 7, and precipitates of In (OH) ₃ and Sn (OH) ₄ were formed. The solution was prepared. The supernatant of the obtained precipitate was removed, filtered, and dried at about 80 ° C. for about 20 hours. The dried powder was further heat treated at about 930 ° C. for about 2 hours to obtain ITO powder particles. As a result of observing the obtained particles with an electron microscope, as shown in Fig. 6, particles having an angular shape were obtained.

The reaction conditions of Examples 1 and 2 and Comparative Examples 1 to 3 are summarized in Table 1 below.

	실시 예 1Example 1	실시 예 2Example 2	비교 예 1Comparative Example 1	비교 예 2Comparative Example 2	비교 예 3Comparative Example 3
ITO 용해액 농도ITO solution concentration	50g/L50 g / L	50g/L50 g / L	50g/L50 g / L	100g/L100 g / L	100g/L100 g / L
알칼리alkali	NH₄OHNH ₄ OH	NH₄OHNH ₄ OH	NH₄OHNH ₄ OH	NH₄OHNH ₄ OH	NH₄OHNH ₄ OH
분산제Dispersant	0.1%0.1%	0.1%0.1%	0.1%0.1%	0%0%	0%0%
용액 pHSolution pH	99	99	77	99	77
열처리 온도Heat treatment temperature	930℃930 ℃	930℃930 ℃	930℃930 ℃	930℃930 ℃	930℃930 ℃
열처리 시간Heat treatment time	2시간2 hours	2시간2 hours	2시간2 hours	2시간2 hours	2시간2 hours
입자 형태Particle shape	구형rectangle	구형rectangle	결정형Crystalline form	결정형Crystalline form	결정형Crystalline form

As can be seen in Table 1, the method of Examples 1 and 2, while the Sn (NH ₄ ) ₃ Cl is not produced, the ITO powder particles are spherical, whereas the ITO powder of Comparative Examples 1 to 3 Crystalline (angular) particles were obtained.

Although the present invention has been described in detail through specific examples, it is intended to describe the present invention in detail, and the present invention is not limited thereto, and it should be understood by those skilled in the art within the technical spirit of the present invention. Modifications or improvements may be possible.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

Claims

a) providing an acid solution in which waste ITO scrap is dissolved in acid;

b) the acid solution is added dropwise to an alkaline solution containing at least one dispersant selected from the group consisting of polyvinyl alcohol, polyethylene glycol, oleylamine, and polyvinylpyrrolidone while stirring and maintaining the pH at 8 to 10 step;

c) filtering and drying the precipitate obtained from the reaction mixture of step b); And

d) calcining the precipitate dried in step c) to obtain ITO powder,

Here, the use amount of the dispersant is a method for producing ITO powder from the waste ITO scrap in the range of 0.05 to 0.3% by weight relative to the alkaline solution.
The method according to claim 1,

The concentration of the solution of the waste ITO scrap dissolved in acid concentration of 0.1 mol / L to 2.0 mol / L from the waste ITO scrap is a method for producing ITO powder in the form of particles.
The method according to claim 1,

A method for producing ITO powder in which the acid solution is added dropwise into the alkaline solution can be controlled in particle form from waste ITO scrap of 10 ml to 50 ml per minute.
The method according to claim 1,

The alkaline component is NaOH, NH 4 OH, NH 4 HCO 3 , or CH 3 COONH 4 A method for producing ITO powder that can control the particle form from waste ITO scrap.
The method according to claim 1,

In the step d), the firing is a method for producing ITO powder can be controlled in the form of particles from the waste ITO scrap carried out at 300 to 900 ℃.