KR101729365B1 - Ito powder and method of producing same - Google Patents

Abstract

Modified ITO powder that exhibits high conductivity when it is formed into a green compact at low pressure.
The surface-modified ITO powder of the present invention has a resistivity of 0.50? Cm or less when a green compact made of ITO powder is applied with a pressure of 0.98 MPa and a pressure of 0.196 to 29.42 MPa is applied to the green compact Wherein the relationship between the pressure and the volume resistivity is Y = aX ⁿ , a is 5.00 or less, and n is -0.500 Or less.

Description

TECHNICAL FIELD [0001] The present invention relates to an ITO powder and an ITO powder,

TECHNICAL FIELD The present invention relates to a surface-modified ITO powder that exhibits high conductivity when formed into a green compact at low pressure, and a method for producing the same. In this specification, ITO refers to indium tin oxide.

The ITO may be In ₂ O ₃ And the doped with tin (Sn) compound, 10 ²⁰ ~ 10 ²¹ cm ^- in having a carrier concentration of ^3, ITO film formed by the gas phase method such as a sputtering method, a low resistivity of about 1 × 10 ^-4 Ω · cm . The ITO film made of ITO has high transparency in the visible light region (see, for example, Patent Document 1). Therefore, the ITO film is required to have excellent optical properties such as a transparent electrode of a liquid crystal display (for example, see Patent Document 2) or a heat ray shielding material having a high heat ray shielding effect (for example, see Patent Document 3) It is widely used in the field. As a film forming method of the ITO film, a film forming method by a simple coating method is studied instead of a physical film forming method such as a high-cost vacuum deposition method or a sputtering method (for example, refer to Patent Document 4).

Japanese Laid-Open Patent Publication No. 2009-032699 (paragraph [0009]) Japanese Laid-Open Patent Publication No. 2005-054273 (paragraph [0006]) Japanese Laid-Open Patent Publication No. 2011-116623 (paragraph [0002]) Japanese Laid-Open Patent Publication No. 2011-034708 (paragraph [0002])

As a method of forming an ITO film, a coating type film forming method has advantages of high material utilization efficiency and productivity, excellent bendability, and little restriction on a substrate to be coated. On the other hand, however, there is a drawback in that the conductivity is low as compared with the physical film-forming method, and the contact resistance between the particles is high.

An object of the present invention is to provide an ITO powder capable of achieving high conductivity by lowering a resistivity when an ITO film is formed as a coating type, and a method for producing the ITO powder.

In a first aspect of the present invention, there is provided a surface-modified ITO powder, wherein a volume resistivity of the green compact when a pressure of 0.98 MPa (10 kgf / cm 2) is applied to the green compact comprising the ITO powder is 0.50? , And when the volume resistivity of the green compact when pressure of 0.196 to 29.42 MPa (2 to 300 kgf / cm2) is applied to the green compact and the pressure is X, the relationship between the pressure and the volume resistivity is Is an ITO powder which is approximated by the following formula (1), wherein a in the formula (1) is 5.00 or less and n is -0.500 or less.

Y = aX ⁿ (One)

According to a second aspect of the present invention, there is provided an invention based on the first aspect, comprising the steps of mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, Cleaning the coprecipitation hydroxide with pure water or ion exchange water; preparing a slurry in which indium tin hydroxide particles are dispersed by discarding the supernatant of the coprecipitation hydroxide; drying the slurry; And a step of firing indium tin oxide to obtain indium tin oxide. It is characterized in that in the cleaning step, the resist is washed until the resistivity of the supernatant is at least 5000 OMEGA -cm, and the concentration of the hydroxide particles is in the range of 10 to 30 mass% in the slurry preparation step An organic protective agent is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring, and after the firing step, an aggregate of the fired ITO powder is added to the slurry The impregnated ITO powder is impregnated into the surface treatment liquid and heated in a nitrogen gas atmosphere at a temperature in the range of 200 to 400 ° C for 0.5 to 5 hours.

A third aspect of the present invention is the method according to the second aspect, wherein the organic protective agent is palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate.

According to a fourth aspect of the present invention, there is provided an invention based on the first aspect, comprising the steps of mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, A step of washing the coprecipitation hydroxide with pure water or ion exchange water; a step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding the supernatant of the coprecipitation hydroxide; drying the slurry; To obtain indium tin oxide. The present invention also provides an improved method for producing ITO powder. It is characterized in that in the cleaning step, the resist is washed until the resistivity of the supernatant is at least 5000 OMEGA -cm, and the concentration of the hydroxide particles is in the range of 10 to 30 mass% in the slurry preparation step The organic slurry is diluted with water and then the organic protective agent is added to the slurry in an amount of 0.1 to 5 mass% with respect to 100 mass% of the hydroxide particles with stirring. In the drying step, the organic protective agent The slurry in which the tin hydroxide is dispersed is dried and heated and fired in a microwave of 2.45 GHz to 28 GHz in the atmosphere in the firing step. After the firing step, the agglomerated ITO powder is pulverized, and the pulverized ITO powder Impregnated with the surface treatment solution, and then heated in a nitrogen gas atmosphere at a temperature of 200 to 400 ° C for 0.5 to 5 hours.

A fifth aspect of the present invention is the method according to the fourth aspect, wherein the organic protective agent is palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate.

According to a sixth aspect of the present invention, there is provided an invention based on the first aspect, comprising the steps of mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, A step of washing the coprecipitation hydroxide with pure water or ion exchange water; a step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding the supernatant of the coprecipitation hydroxide; drying the slurry; To obtain indium tin oxide. The present invention also provides an improved method for producing ITO powder. It is characterized in that, in the cleaning step, the cleaning is performed until the resistivity of the supernatant is at least 5000 Ω · cm, and the concentration of the hydroxide particles is in the range of 1 to 5 mass% Diluting the slurry in which the supernatant liquid has been removed with alcohol, adding an organic protective agent to the slurry in an amount of 0.1 to 5 mass% with respect to 100 mass% of the hydroxide particles with stirring, and in the firing step, A slurry in which indium tin hydroxide particles having been added with an organic protective agent are dispersed is circulated in a tubular furnace heated to a temperature in the range of 250 to 800 DEG C at a linear velocity of 0.5 to 5 m / In which the indium tin hydroxide particles are pyrolyzed and fired in the tubular furnace to obtain indium tin oxide particles.

A seventh aspect of the present invention resides in an invention based on the sixth aspect, wherein the alcohol is ethanol, methanol or propanol, and the organic protective agent is palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate Lt; RTI ID = 0.0 > ITO < / RTI >

An eighth aspect of the present invention is a method for producing a dispersion by dispersing an ITO powder of the first aspect or an ITO powder produced by any one of the second to seventh aspects of the present invention in a solvent.

The ninth aspect of the present invention is a method for producing an ITO film from the dispersion liquid of the eighth aspect.

The ITO powder according to the first aspect of the present invention has a volume resistivity of the green compact of the ITO powder when the pressure of 0.98 MPa (10 kgf / cm 2) is applied is 0.50 Ω · cm or less and 0.196 to 29.42 MPa (1), when the volume resistivity of the green compact is Y and the pressure is X when applying a pressure of 300 kgf / cm 2 to 300 kgf / cm 2, And n is less than or equal to -0.500, a resistivity when the ITO film is formed into a coating type using the ITO powder is lowered, and high conductivity can be obtained.

In the method of manufacturing an ITO powder according to the second aspect of the present invention, the cleaning is performed until the resistivity of the supernatant is at least 5000 Ω · cm, and the concentration of the hydroxide particles is 10 to 30 mass %. The organic protective agent is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring. After the firing step, the fired ITO powder And the pulverized ITO powder is impregnated in the surface treatment liquid and then heated in a nitrogen gas atmosphere at a temperature of 200 to 400 ° C for 0.5 to 5 hours. Since the hydroxide particles are encapsulated with an organic protective agent having a relatively high decomposition temperature, the contact of the ITO particles with each other is prevented during the firing process, and the particles are difficult to grow. This organic protective agent is finally pyrolyzed by baking. As a result, the surface of the ITO powder is modified, and by using the ITO powder, the resistivity when the ITO film is formed as a coating type is lowered, and high conductivity can be obtained.

In the method for producing an ITO powder according to the fourth aspect of the present invention, in the cleaning step, the solution is washed until the resistivity of the supernatant is at least 5000 OMEGA -cm, and the concentration of the hydroxide particles is 10 to 30 mass %, And then adding an organic protective agent to the slurry in an amount in the range of 0.1 to 5 mass% with respect to 100 mass% of the hydroxide particles with stirring. In the drying step, the organic protective agent is added A slurry in which an indium tin hydroxide is dispersed is dried and heated and fired in a microwave of 2.45 GHz to 28 GHz in the air in a firing step. After the firing step, the agglomerated ITO powder is pulverized, and the pulverized ITO powder After impregnating with the surface treatment solution, it is heated in a nitrogen gas atmosphere at a temperature of 200 to 400 ° C for 0.5 to 5 hours. Since the hydroxide particles are coated with an organic protective agent having a relatively high decomposition temperature, the contact of the ITO particles with each other in the firing process is inhibited and the particles are difficult to grow. This organic protective agent is finally pyrolyzed by baking. As a result, the surface of the ITO powder is modified, and by using the ITO powder, the resistivity when the ITO film is formed as a coating type is lowered, and high conductivity can be obtained.

In the method of manufacturing an ITO powder according to the sixth aspect of the present invention, in the cleaning step, the solution is washed until the resistivity of the supernatant is at least 5000 Ω · cm, and the concentration of the hydroxide particles is 1 to 5 % By mass of the slurry is diluted with alcohol, and then the organic protective agent is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring. In the firing step, A slurry in which indium tin hydroxide particles having been diluted and added with an organic protective agent are dispersed is flowed in a tubular furnace heated to a temperature in the range of 250 to 800 DEG C under nitrogen gas at a linear velocity of 0.5 to 5 m / , Indium tin hydroxide particles are pyrolyzed and fired in a tubular furnace to obtain indium tin oxide particles. Since the hydroxide particles are coated with an organic protective agent having a relatively high decomposition temperature, the contact of the ITO particles with each other in the firing process is inhibited and the particles are difficult to grow. This organic protective agent is finally pyrolyzed by baking. As a result, the surface of the ITO powder is modified, and by using the ITO powder, the resistivity when the ITO film is formed as a coating type is lowered, and high conductivity can be obtained.

1 is a schematic view of an apparatus for measuring a resistivity of a green compact of ITO powder.
2 is a view showing a relationship between an applied pressure and a resistivity of a green compact of an ITO powder;

Next, a mode for carrying out the present invention will be described.

The resistivity of the ITO powder is an important index in evaluating the characteristics of the ITO film made of this ITO powder. In particular, when the ITO film is used as a conductive sheet or electrode, high conductivity, that is, a low resistivity is required. The resistivity of the ITO powder is determined by measuring the volume resistivity of the ITO powder in the form of a green compact. On the other hand, the volume resistivity of the green compact changes depending on the applied pressure. Therefore, the volume resistivity of the green compact at a predetermined pressure is once a standard. However, depending on the shape and specific surface area of the ITO powder, the volume resistivity is obtained in a state in which the pressure is changed from a low pressure to a high pressure. When the resistivity is used, the resistivity of the ITO powder with higher precision can be obtained. The present invention has been made based on this finding.

The ITO powder of the present invention is a surface-modified ITO powder, and the volume resistivity of the green compact when a green compact made of ITO powder is applied at a pressure of 0.98 MPa (10 kgf / cm 2) is 0.50? Cm or less, When the volume resistivity of the green compact is 0.196 to 29.42 MPa (2 to 300 kgf / cm 2) and the pressure is X, the relationship between the pressure and the volume resistivity is represented by the following equation (1) Approximate. Here, a in the formula (1) is 5.00 or less, and n is -0.500 or less.

Y = aX ⁿ (One)

This formula is derived based on the result of measuring the surface-modified ITO powder having a low volume resistivity in a green state. When the value of a is more than 5.00 or n is more than -0.500, there is a problem that the applied pressure to the powder is large, that is, even if the contact between the particles is made strong, the conductivity tends to be hard to be improved.

The ITO powder used in the production of the ITO film of the present invention is a surface-modified ITO powder prepared by the following three methods. The surface modification treatment can improve the conductivity of the ITO film produced using this ITO powder.

(1) First Manufacturing Method

The ITO powder is obtained by mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, drying the precipitate and firing, and then pulverizing the obtained indium tin oxide . Examples of the _trivalent indium compound include indium trichloride (InCl ₃ ), indium nitrate (In (NO ₃ ) ₃ ), indium acetate (In (CH ₃ COO) ₃ ), and the divalent tin compounds include tin dichloride SnCl ₂ .2H ₂ O), tin sulfate (SnSO ₄ ), and tin bromide (SnBr ₂ ). Examples of the aqueous alkali solution include ammonia (NH ₃ ) water and ammonium hydrogen carbonate (NH ₄ HCO ₃ ) water. By adjusting the final pH of the reaction solution when the indium and tin hydroxides are coprecipitated at 3.5 to 9.3, preferably at pH 5.0 to 8.0, at a solution temperature of 5 deg. C or higher, preferably at a solution temperature of 10 deg. C to 80 deg. And co-precipitation hydroxides of tin can be precipitated. The mixing of the alkaline aqueous solution is carried out while dropping the alkaline aqueous solution into the mixed aqueous solution and adjusting the pH to the above range or by simultaneously dropping the mixed aqueous solution and the alkaline aqueous solution into the water and adjusting the pH to the above range.

After the formation of the coprecipitated indium tin hydroxide, the precipitate is washed with pure water or ion exchange water, and the solution is washed until the resistivity of the supernatant is at least 5000 Ω · cm, preferably at least 50,000 Ω · cm. If the resistivity of the supernatant is lower than 5,000 OMEGA .cm, impurities such as chlorine can not be sufficiently removed and a high-purity indium tin oxide powder can not be obtained. The supernatant of the precipitate having a resistivity of 5000 OMEGA .cm or more is discarded to obtain a slurry in which indium tin hydroxide particles are dispersed to have a high viscosity. The slurry is diluted with pure water or ion-exchanged water so that the concentration of the hydroxide particle is in the range of 10 to 30 mass%, preferably 15 to 25 mass%, and then adsorbed on the surface of the hydroxide particle to improve dispersibility of the particle Is added to the slurry with stirring. If the dilution range is below the lower limit, there is a problem that it takes time to dry the slurry. If the dilution range is over the upper limit, there is a problem that the organic protective agent is mixed with the slurry having a high viscosity, resulting in insufficient mixing of the organic protective agent. The amount of the organic protective agent to be added is in the range of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles. From the viewpoint of suppressing the sintering of the ITO powder after pyrolysis, the organic protective agent preferably has a decomposition temperature of 250 to 500 ° C. Examples of the organic protective agent include palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate. When the amount of the organic protective agent is less than the lower limit of the above range, the surface of the hydroxide particle is not sufficiently protected and the dispersibility of the particles is inferior. On the other hand, if the upper limit is exceeded, there arises a problem that a part of the organic substance or a carbon content derived from the organic substance remains.

The indium tin hydroxide adsorbed on the surface of the organic protective agent is dried in an atmosphere of inert gas such as nitrogen or argon in the range of 100 to 200 DEG C for 2 to 24 hours and then exposed to the atmosphere in the range of 250 to 800 DEG C In a furnace for 0.5 to 6 hours. The agglomerated body formed by this firing is pulverized using a hammer mill, a ball mill or the like and loosened to obtain an ITO powder. The ITO powder was impregnated in a surface treating solution prepared by mixing 50 to 95 mass% of anhydrous ethanol and 5 to 50 mass% of distilled water, and then impregnated in a glass chalet. When the mixture is heated for 5 hours, the surface-modified ITO powder is obtained.

(2) Second Manufacturing Method

The solid-liquid separation method of the slurry and the heat firing method differ from the first production method. First, the slurry in which the indium tin hydroxide with the organic protective agent obtained in the first production method is dispersed is dried. As an example of this drying method, a slurry is press-fitted into a filter press with a pressurizing pump to obtain a sludge cake of hydroxide, and this cake is dried. The dried material is then heated and fired in a microwave of 2.45 GHz to 28 GHz in the air. The microwave heating process is carried out, for example, by filling the cake in a microwave oven manufactured by Shimushi Technology Development Co., Ltd. and using a microwave heating process of 2.45 GHz in a μ-reactor manufactured by Shikoku Industry Co., Ltd.

The microwave heating is carried out by raising the temperature to a target temperature within a range of 250 to 800 ° C, preferably 350 to 600 ° C within 10 minutes, and the firing is carried out at a target temperature for 5 to 120 minutes, preferably 10 to 60 minutes Min. ≪ / RTI > If the heating temperature is lower than the lower limit, there is a problem that the hydroxide is not completely decomposed into oxides, and when the upper limit is exceeded, the ITO particles are coarsened. If the temperature rise time to the target temperature exceeds 10 minutes, the effect of rapid temperature increase disappears. When the holding time at the target temperature is lower than the lower limit, there is a problem that the hydroxide is not completely decomposed into oxides. When the upper limit is exceeded, there is a problem that the ITO particles are coarsened. The fired product is pulverized and pulverized using a hammer mill, a ball mill or the like to obtain an ITO powder. Hereinafter, in the same manner as in the first production method, the surface-modified ITO powder is obtained.

(3) Third Manufacturing Method

The first and second production methods are different in that the indium tin oxide does not need to be pulverized after the indium tin hydroxide is calcined.

The slurry having a high viscosity, in which the indium tin hydroxide particles obtained in the first production method are dispersed, is diluted with alcohol so that the concentration of the hydroxide particles is in the range of 1 to 5 mass%, preferably 1 to 3 mass% An organic protective agent for adsorbing and improving the dispersibility of the particles is added to the slurry while stirring. The amount of the organic protective agent to be added is in the range of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles. The reason for defining the respective lower limit values and upper limit values of the dilution range and the range of addition amounts of the organic protective agent is the same as in the first production method. From the viewpoint of suppressing the sintering of the ITO powder after pyrolysis, the organic protective agent preferably has a decomposition temperature of 250 to 500 ° C. Examples of the alcohol include ethanol, propanol, and methanol. Examples of the organic protective agent include palmityl dimethylethyl ammonium ethyl sulfate, polyvinyl alcohol, and octyldimethylethyl ammonium ethyl sulfate.

A slurry in which indium tin hydroxide particles dispersed with an organic protective agent diluted with alcohol are dispersed is placed in a tubular furnace heated to a temperature in the range of 250 to 800 占 폚 with the longitudinal direction of the tube being vertically arranged, The gas is introduced into the tubular furnace together with the nitrogen gas by using a two-fluid nozzle while spraying the gas at a linear velocity ranging from 0.5 to 5 m / s, preferably from 1 to 3 m / s. When the linear velocity is lower than the lower limit, the amount of the ITO powder is decreased. When the upper limit is exceeded, the sprayed slurry is not sufficiently heated. As a result, the indium tin hydroxide particles are pyrolyzed and fired in the tubular furnace to obtain an ITO powder which has been surface-modified from the outlet of the tubular furnace.

Example

Next, examples of the present invention will be described in detail with reference to comparative examples.

≪ Example 1 >

[Preparation of surface-modified ITO powder]

4 g of tin dichloride powder (SnCl ₂ .2H ₂ O powder) was added to 163 g of an indium chloride (InCl ₃ ) aqueous solution having an In metal concentration of 24 mass% and stirred until all the tin dichloride tin powder was dissolved Then, the total amount was added to 1000 ml of pure water to obtain a raw material solution. An aqueous solution of 25% by mass of ammonia (NH ₃ ) was added dropwise to the raw material solution over 90 minutes. At this time, the reaction temperature was adjusted to 80 ° C and the pH of the final reaction solution was adjusted to 8.0. The resulting indium tin co-precipitate hydroxide precipitate was repeatedly washed with ion-exchanged water to perform oblique washing. When the resistivity of the supernatant reached 5000 Ω · cm or more, the supernatant of the precipitate was discarded to obtain a slurry in which the indium tin hydroxide particles were dispersed to have a high viscosity.

While stirring the slurry, the slurry was diluted with pure water so that the concentration of the hydroxide particles became 20 mass%, and then 1.3 g of polyvinyl alcohol as an organic protective agent was added. The addition amount of the organic protective agent was 1.0% by mass based on the indium tin hydroxide. The slurry was dried in the atmosphere at 110 DEG C for 10 hours and then calcined at 700 DEG C for 2 hours in the atmosphere. The agglomerates were pulverized and pulverized to obtain about 70 g of ITO powder. This ITO powder (70 g) was impregnated with a surface treatment liquid (mixing ratio: 5 mass% of distilled water with respect to 95 mass% of ethanol) in which anhydrous ethanol and distilled water were mixed and placed in a glass chalet. Hr to obtain a surface-modified ITO powder.

[Production of ITO film]

20 g of the surface-modified ITO powder was mixed with distilled water (0.020 g), triethylene glycol-di-2-ethylhexanoate [3G] (23.8 g), anhydrous ethanol (2.1 g) and phosphoric acid polyester ), 2-ethylhexanoic acid (2.0 g) and 2,4-pentanedione (0.5 g). The prepared dispersion was diluted with anhydrous ethanol until the content of solid ITO powder was 10 mass%. This diluted dispersion was coated on a quartz glass plate by spin coating to form an ITO film having a thickness of 0.2 탆.

≪ Example 2 >

16 g of tin dichloride powder (SnCl ₂ .2H ₂ O powder) was added to 135 g of an aqueous solution of indium chloride (InCl ₃ ) having an In metal concentration of 24 mass% and stirred until all of the tin dichloride tin powder was dissolved Then, the total amount was added to 1000 ml of pure water to obtain a raw material solution. An aqueous solution of 25% by mass of ammonia (NH ₃ ) was added dropwise to the raw material solution over 90 minutes. At this time, the reaction temperature was adjusted to 60 ° C and the pH of the final reaction solution was adjusted to 5.0. The resulting indium tin co-precipitate hydroxide precipitate was repeatedly washed with ion-exchanged water to perform oblique washing. When the resistivity of the supernatant reached 5000 Ω · cm or more, the supernatant of the precipitate was discarded to obtain a slurry in which the indium tin hydroxide particles were dispersed to have a high viscosity. While stirring the slurry, the slurry was diluted with purified water so that the concentration of the hydroxide particles became 15 mass%, and then 4.5 g of palmityl dimethylethylammonium ethyl sulfate (70 mass%) as an organic protective agent was added. The amount of the organic protective agent added was 3.0% by mass based on the indium tin hydroxide.

The slurry was dried in the atmosphere at 110 DEG C for 10 hours and then calcined at 800 DEG C for 3 hours in the atmosphere. The aggregates were pulverized and pulverized to obtain about 75 g of ITO powder. This ITO powder (75 g) was impregnated with a surface treatment liquid (mixing ratio: 5 mass% of distilled water with respect to 95 mass% of ethanol) in which anhydrous ethanol and distilled water were mixed and placed in a glass chalet. Hr to obtain a surface-modified ITO powder. An ITO film was produced in the same manner as in Example 1 using this ITO powder.

≪ Example 3 >

8 g of tin dichloride powder (SnCl ₂ .2H ₂ O powder) was added to and mixed with 154 g of an aqueous solution of indium chloride (InCl ₃ ) having an In metal concentration of 24 mass% and stirred until all the tin dichloride tin powder was dissolved Then, the total amount was added to 1000 ml of pure water to obtain a raw material solution. An aqueous solution of 25% by mass of ammonia (NH ₃ ) was added dropwise to the raw material solution over 90 minutes. At this time, the reaction temperature was adjusted to 20 ° C and the pH of the final reaction solution was adjusted to 7.0. The resulting indium tin co-precipitate hydroxide precipitate was repeatedly washed with ion-exchanged water to perform oblique washing. When the resistivity of the supernatant reached 5000 Ω · cm or more, the supernatant of the precipitate was discarded to obtain a slurry in which the indium tin hydroxide particles were dispersed to have a high viscosity. While stirring the slurry, the slurry was diluted with ethanol so that the concentration of the hydroxide particles became 1.0% by mass, and 10 g of octyldimethylethylammonium ethylsulfate (50% by mass) as an organic protective agent was added. The addition amount of the organic protective agent was 5.0% by mass based on the indium tin hydroxide.

In a state in which nitrogen gas as a carrier gas is flowed at a linear velocity of 1 m / s into a tubular furnace heated to 500 캜 in which the slurry is arranged vertically in the longitudinal direction of the tube, Was sprayed and introduced into the tubular furnace together with nitrogen gas. As a result, indium tin hydroxide particles were pyrolyzed and fired in a tubular furnace to obtain an ITO powder that was surface-modified from the outlet of the tubular furnace. An ITO film was produced in the same manner as in Example 1 using this ITO powder.

≪ Comparative Example 1 &

An InCl ₃ -SnCl ₄ mixed solution was prepared by adding and mixing 11.5 g of a 55% by mass aqueous solution of tin tetrachloride (SnCl ₄ ) to 245 g of an indium chloride (InCl ₃ ) aqueous solution having an In metal concentration of 24% by mass. Subsequently, 500 g of ammonium hydrogen carbonate (NH ₄ HCO ₃ ) water was dissolved in ion-exchanged water to prepare a total amount of 1000 ml at a temperature of 70 ° C. The total amount of the InCl ₃ -SnCl ₄ mixed solution was added dropwise to this aqueous solution with stirring for about 20 minutes to produce an indium tin co-precipitate hydroxide. The mixture was stirred again for 30 minutes. The final pH of the reaction solution at this time was 9.0. The indium tin hydroxide as a precipitate was recovered, dehydrated by a centrifugal separator, and subjected to centrifugal filtration while washing with ion-exchanged water. The centrifugal filtration was terminated when the resistivity of the filtrate reached 5000 Ω · cm or more . Subsequently, this precipitate was dried at 100 ° C. overnight, and then calcined at 600 ° C. for 3 hours. The aggregate was pulverized and pulverized to obtain 75 g of ITO powder.

This ITO powder (75 g) was impregnated with a surface treatment solution (mixture ratio: 5% by mass of distilled water with respect to 95% by mass of ethanol) mixed with anhydrous ethanol and distilled water and placed in a glass chalet. Hr to obtain a surface-modified ITO powder. An ITO film was produced in the same manner as in Example 1 using this ITO powder.

<Comparative Test>

[Evaluation of ITO Powder]

The following Table 1 shows the volume resistivities of the green compacts obtained by applying the pressure of 0.98 MPa (10 kgf / cm 2) to the green compacts comprising the ITO powders obtained in Examples 1 to 3 and Comparative Example 1. The volume resistivity of each ITO powder obtained in Examples 1 to 3 and Comparative Example 1 was measured using a measuring device (MCP-PD51 manufactured by Mitsubishi Chemical Corporation) shown in Fig. Specifically, 2.00 g of ITO powder was charged into a cylinder 1 having an inner diameter? Of 25 mm shown in Fig. 1, and the pressure was changed in the range of 0.196 to 29.42 MPa (2 to 300 kgf / cm2) The resistivity and the sample thickness of the ITO powder obtained in Examples 1 to 3 and Comparative Example 1 were measured simultaneously. The pressure was measured by a pressure sensor (not shown), and the resistivity was measured by a DC four-terminal method. In Fig. 1, 2 is a green compact of ITO powder.

Fig. 2 shows the relationship between the pressure (horizontal axis) converted to a force per unit area added to the sample powder and the volume resistivity (vertical axis) of the green compact of the ITO powder. This relationship is approximated by the least squares method to the following power equation (1). In addition, the volume resistivity of the powder is calculated by multiplying the measured value by the correction coefficient of the measuring system. Table 1 shows the values of a and n in the approximation formula (1) obtained in Examples 1 to 3 and Comparative Example 1.

Y = aX ⁿ (One)

The surface resistivity (? /?) Of each ITO film obtained in Examples 1 to 3 and Comparative Example 1 was measured by a resistivity measuring device (MCP-T400, manufactured by Mitsubishi Yucca). The results are shown in Table 1.

<Evaluation>

As is evident from Table 1, the green compact of the ITO powder of Examples 1 to 3, in which a in Formula (1) was 5.00 or less and n was -0.500 or less, was subjected to a pressure of 0.98 MPa (10 kgf / The volume resistivity of the green compact was 0.500? · Cm or less. The surface resistivity of the ITO film made of the ITO powder was 1.0 x 10 ⁶ ? /? Or less. On the other hand, when the green color of the ITO powder of Comparative Example 1 in which a in Formula (1) is 5.00 or less, and n is more than -0.500, the volume of the green compact when a pressure of 0.98 MPa (10 kgf / The resistivity exceeded 0.5 Ω · cm. The surface resistivity of the ITO film made of the ITO powder of Comparative Example 1 was more than 1.0 x 10 ⁶ ? / ?. From the above, it was proved that Examples 1 to 3 having an approximate relationship to the formula (1) obtain a high conductivity by lowering the resistivity when the ITO film is formed as a coating type.

Claims (9)

A coprecipitation hydroxide of indium and tin is produced by mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound, and the coprecipitated hydroxide is mixed with pure water (deionized water) until the resistivity of the supernatant is at least 5000? ) Or ion-exchanged water, discarding the supernatant of the coprecipitation hydroxide to prepare a slurry in which indium tin hydroxide particles are dispersed, and removing the supernatant slurry so that the concentration of the hydroxide particles is in the range of 10 to 30 mass% And an organic protective agent such as palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate is added to the slurry in an amount of 0.1 to 5 mass% with respect to 100 mass% of the hydroxide particles with stirring , The indium tin hydroxide adsorbed on the surface of the organic protective agent is dried, And the agglomerated ITO powder is pulverized. The pulverized ITO powder is mixed with 50 to 95 mass% of anhydrous ethanol and 5 to 50 mass% of distilled water The ITO powder is impregnated with the treatment liquid and then heated in a nitrogen gas atmosphere at a temperature in the range of 200 to 400 ° C for 0.5 to 5 hours to obtain a green colored ITO powder, When the volume resistivity of the green compact is 0.50? 占 cm m or less and the volume resistivity of the green compact when pressure of 0.196 to 29.42 MPa is applied to the green compact is Y and the pressure is X, (1), wherein a is 5.00 or less, and n is -0.500 or less, according to the following formula (1).
Y = aX ⁿ (1) A step of mixing an alkaline aqueous solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, a step of washing the coprecipitated hydroxide with pure water or ion exchange water, A step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding a supernatant of a hydroxide, a step of drying the slurry, and a step of firing the dried indium tin oxide to obtain indium tin oxide In this case,
In the cleaning step, the resist is washed until the resistivity of the supernatant is at least 5000 Ω · cm,
In the process of preparing the slurry, the slurry obtained by removing the supernatant liquid is diluted with water so that the concentration of the hydroxide particle is in the range of 10 to 30 mass%, and then the mixture is diluted with palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium Ethyl sulfate is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring,
After drying the indium tin hydroxide adsorbed on the surface of the organic protective agent, the indium tin hydroxide is sintered in a calcination furnace in the atmosphere at 250 to 800 ° C. for 0.5 to 6 hours in the atmosphere,
After the firing step, the agglomerated ITO powder was pulverized, and the pulverized ITO powder was impregnated with a surface treatment solution obtained by mixing 50 to 95 mass% of anhydrous ethanol and 5 to 50 mass% of distilled water. Then, nitrogen gas The method for producing an ITO powder according to claim 1, wherein the composition is heated in a temperature range of 200 to 400 ° C for 0.5 to 5 hours. A coprecipitation hydroxide of indium and tin is produced by mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound, and the coprecipitated hydroxide is purified or ion-exchanged until the resistivity of the supernatant is at least 5000? And the supernatant of the coprecipitation hydroxide was discarded to prepare a slurry in which indium tin hydroxide particles were dispersed. The slurry in which the supernatant was removed was diluted with water so that the concentration of the hydroxide particle was in the range of 10 to 30 mass% An organic protective agent such as t-butyldimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring, The slurry in which the indium tin hydroxide was dispersed was dried. Heated to a temperature within a range of 250 to 800 ° C in a microwave of 45 GHz to 28 GHz at a rate of reaching a target temperature within 10 minutes and then maintained at the above-mentioned target temperature for 5 to 120 minutes, The agglomerate of the powder is pulverized and the pulverized ITO powder is impregnated with a surface treating solution obtained by mixing 50 to 95 mass% of anhydrous ethanol and 5 to 50 mass% of distilled water, Wherein the volume resistivity of the green compact when applying a pressure of 0.98 MPa to the green compact comprising the ITO powder as the surface-modified ITO powder by heating for 0.5 to 5 hours in the range of 0.196 And the volume resistivity of the green compact when the pressure of 29.42 MPa is applied is represented by Y and the pressure is represented by X, the relationship between the pressure and the volume resistivity is expressed by the following formula An ITO powder characterized by being approximated by the formula (1), wherein in the formula (1), a is 5.00 or less and n is -0.500 or less.
Y = aX ⁿ (1) A step of mixing an alkaline aqueous solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, a step of washing the coprecipitated hydroxide with pure water or ion exchange water, A step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding a supernatant of a hydroxide, a step of drying the slurry, and a step of firing the dried indium tin oxide to obtain indium tin oxide In this case,
In the cleaning step, the resist is washed until the resistivity of the supernatant is at least 5000 Ω · cm,
In the process of preparing the slurry, the slurry obtained by removing the supernatant liquid is diluted with water so that the concentration of the hydroxide particle is in the range of 10 to 30 mass%, and then the mixture is diluted with palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium Ethyl sulfate is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring,
In the drying step, the slurry in which indium tin hydroxide to which the organic protective agent is added is dispersed,
In the firing step, the temperature is raised in the range of 250 to 800 ° C in a microwave of 2.45 GHz to 28 GHz in the air at a rate of reaching the target temperature within 10 minutes, and then maintained at the target temperature for 5 to 120 minutes, Then,
After the firing step, the agglomerated ITO powder was pulverized, and the pulverized ITO powder was impregnated with a surface treatment solution obtained by mixing 50 to 95 mass% of anhydrous ethanol and 5 to 50 mass% of distilled water. Then, nitrogen gas Wherein the heating is carried out at a temperature in the range of 200 to 400 DEG C for 0.5 to 5 hours. A coprecipitation hydroxide of indium and tin is produced by mixing an aqueous alkaline solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound, and the coprecipitated hydroxide is purified or ion-exchanged until the resistivity of the supernatant is at least 5000? And the supernatant of the coprecipitation hydroxide is discarded to prepare a slurry in which indium tin hydroxide particles are dispersed. The slurry in which the supernatant is removed is diluted with alcohol so that the concentration of the hydroxide particle is in the range of 1 to 5 mass% An organic protective agent, such as palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethylammonium ethylsulfate, is added to the slurry in an amount of 0.1 to 5 mass% with respect to 100 mass% of the hydroxide particles with stirring, And the slurry in which the indium tin hydroxide particles added with the organic protective agent are dispersed The indium tin hydroxide particles were sprayed in the tubular furnace heated to a temperature in the range of 250 to 800 DEG C while nitrogen gas was circulated in the range of 0.5 to 5 m / Wherein the volume resistivity of the green compact when a pressure of 0.98 MPa is applied to the green compact composed of the ITO powder is not more than 0.50? Cm and the green compact is applied in an amount of 0.196 to 29.42 MPa The relationship between the pressure and the volume resistivity is approximated by the following formula (1) by the least squares method, and when the volume resistivity of the green compact is Y and the pressure is X, Wherein in the formula (1), a is 5.00 or less and n is -0.500 or less.
Y = aX ⁿ (1) A step of mixing an alkaline aqueous solution with a mixed aqueous solution of a trivalent indium compound and a divalent tin compound to produce a coprecipitated hydroxide of indium and tin, a step of washing the coprecipitated hydroxide with pure water or ion exchange water, A step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding a supernatant of a hydroxide and a step of firing a slurry in which the indium tin hydroxide is dispersed to obtain indium tin oxide,
In the cleaning step, the resist is washed until the resistivity of the supernatant is at least 5000 Ω · cm,
In the process of preparing the slurry, the slurry in which the supernatant is removed is diluted with alcohol so that the concentration of the hydroxide particle is in the range of 1 to 5 mass%, and then the mixture is diluted with an aqueous solution of palmityl dimethylethylammonium ethylsulfate, polyvinyl alcohol or octyldimethylethyl Ammonium ethylsulfate is added to the slurry in an amount of 0.1 to 5% by mass based on 100% by mass of the hydroxide particles with stirring,
In the sintering step, a slurry in which indium tin hydroxide particles having been diluted with the alcohol and added with the organic protective agent is dispersed is heated in the range of 250 to 800 ° C, and nitrogen gas is introduced at a linear velocity of 0.5 to 5 m wherein the indium tin hydroxide particles are pyrolyzed and fired in the tubular furnace to obtain indium tin oxide particles, wherein the indium tin hydroxide particles are obtained by spraying in a state in which the particles are dispersed in the range of from 0.1 to 10 m / s. The method according to claim 6,
Wherein the alcohol is ethanol, methanol or propanol. The ITO powder according to any one of claims 1 to 5 or the ITO powder produced by the method according to any one of claims 2 to 5 is dispersed in a solvent to form a dispersion &Lt; / RTI &gt; A method for producing an ITO film using the dispersion liquid according to claim 8.

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