KR20140041330A

KR20140041330A - Ito powder and method of producing same

Info

Publication number: KR20140041330A
Application number: KR1020130095586A
Authority: KR
Inventors: 다케히로 요네자와; 가즈히코 야마사키; 아이 다케노시타
Original assignee: 미쓰비시 마테리알 가부시키가이샤
Priority date: 2012-09-27
Filing date: 2013-08-12
Publication date: 2014-04-04
Also published as: KR101650611B1; TWI577636B; JP5924214B2; CN103693679B; TW201431791A; CN103693679A; JP2014065644A

Abstract

Provided is a surface-modified ITO powder exhibiting high conductivity when formed into a green compact at low pressure.
When the surface-modified ITO powder of this invention makes the volume resistivity of the said green compact at the time of applying the pressure of 0.196-29.42 MPa to the green compact which consists of this ITO powder as Y, and makes the relative density of the said green compact into X, The relationship between the volume resistivity and the relative density is approximated by Y = aX ⁿ , a is 5.0 × 10 ⁻³ or less, and n is −10 or more.

Description

ITO powder and its manufacturing method {ITO POWDER AND METHOD OF PRODUCING SAME}

This invention relates to the surface-modified ITO powder which shows high electroconductivity when it is made into a green compact at low pressure, and its manufacturing method. In the present specification, ITO refers to indium tin oxide.

ITO is 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 Is obtained. The ITO film made of this ITO has high transparency in visible light region (for example, refer patent document 1). For this reason, an ITO film | membrane requires excellent optical characteristics, such as a transparent electrode (for example, patent document 2) of a liquid crystal display, and a heat ray shielding material (for example, patent document 3) with a high heat ray shielding effect. It is used a lot in the field. As a film-forming method of this ITO film | membrane, the film-forming method by simple application | coating is examined instead of physical film-forming methods, such as a vacuum evaporation method and sputtering method, which are expensive (for example, refer patent document 4).

Japanese Unexamined Patent Publication No. 2009-032699 (paragraph [0009]) Japanese Laid-Open Patent Publication 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, the coating type film forming method has advantages of high material use efficiency and productivity, excellent flexibility, and low restrictions on the substrate to be coated. On the other hand, compared with the physical type film-forming method, since the particle | grains themselves had low electroconductivity and the contact resistance of particle | grains was high, there existed a fault with low electroconductivity.

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

A first aspect of the present invention is a surface-modified ITO powder, wherein the volume resistivity of the green compact is Y when a pressure of 0.196 to 29.42 MPa (2 to 300 kgf / cm 2) is applied to the green compact comprising the ITO powder. When the relative density of the green compact is X, the relationship between the volume resistivity and the relative density is approximated by the following formula (1), in which a is 5.0 × 10 ^-3 or less, And n is -10 or more.

Y = aX ⁿ (1)

Moreover, the 2nd viewpoint of this invention is invention based on a 1st viewpoint, The process of mixing an aqueous alkali solution in the mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound, and producing the coprecipitation hydroxide of indium and tin, The said Washing the co-precipitated hydroxide with pure water or ion-exchanged water, disposing the supernatant liquid of the co-precipitated hydroxide, preparing a slurry in which indium tin hydroxide particles are dispersed, drying the slurry, and drying It is an improvement of the method of manufacturing the ITO powder including the process of baking an indium tin oxide and obtaining an indium tin oxide. The characteristic point is to wash | clean until the resistivity of the supernatant liquid is at least 5000 ohm * cm in the said washing | cleaning process, and in the preparation process of the said slurry so that the density | concentration of the said hydroxide particle may be in the range of 10-30 mass%. After diluting the slurry which discarded the said supernatant with water, the organic protective agent is added to the said slurry with stirring in the range of 0.1-5 mass% with respect to 100 mass% of said hydroxide particles, and after the said baking process, the aggregate of the baked ITO powder was added. After pulverizing and impregnating this pulverized ITO powder in a surface treatment liquid, it heats in the range of 200-400 degreeC in a nitrogen gas atmosphere for 0.5 to 5 hours.

A third aspect of the present invention is the invention based on the second aspect, wherein the organic protective agent is a method for producing ITO powder wherein palmityldimethylethylammoniumethylsulfate, polyvinylalcohol or octyldimethylethylammoniumethylsulfate.

Moreover, the 4th viewpoint of this invention is an invention based on a 1st viewpoint, Comprising: The process of mixing the aqueous alkali solution in the mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound, and producing the coprecipitation hydroxide of indium and tin, The said Washing the co-precipitated hydroxide with pure water or ion-exchanged water, disposing the supernatant of the co-precipitated hydroxide, preparing a slurry in which indium tin hydroxide particles are dispersed, drying the slurry, and drying the indium tin oxide. It is an improvement of the method of manufacturing ITO powder including the process of baking and obtaining an indium tin oxide. The characteristic point is to wash | clean until the resistivity of the supernatant liquid is at least 5000 ohm * cm in the said washing | cleaning process, and in the preparation process of the said slurry so that the density | concentration of the said hydroxide particle may be in the range of 10-30 mass%. After diluting the slurry which discarded the said supernatant with water, the organic protecting agent is added to the said slurry with stirring in the range of 0.1-5 mass% with respect to 100 mass% of said hydroxide particles, and in the drying process, the indium which added the said organic protecting agent was carried out. The slurry in which tin hydroxide was disperse | distributed was dried, and it calcined by heat with the microwave of 2.45 GHz-28 GHz in air | atmosphere in the said baking process, After the said baking process, the aggregate of the baked ITO powder was grind | pulverized, and this pulverized ITO powder was After impregnation with the surface treatment liquid, it heats for 0.5 to 5 hours in 200-400 degreeC in nitrogen gas atmosphere.

A fifth aspect of the present invention is the invention based on the fourth aspect, wherein the organic protective agent is a method for producing ITO powder, wherein the organic protective agent is palmityldimethylethylammoniumethylsulfate, polyvinyl alcohol, or octyldimethylethylammoniumethylsulfate.

Moreover, the 6th viewpoint of this invention is an invention based on a 1st viewpoint, Comprising: The process of mixing the aqueous alkali solution in the mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound, and producing the coprecipitation hydroxide of indium and tin, The said Washing the co-precipitated hydroxide with pure water or ion-exchanged water, disposing the supernatant of the co-precipitated hydroxide, preparing a slurry in which indium tin hydroxide particles are dispersed, drying the slurry, and drying the indium tin oxide. It is an improvement of the method of manufacturing ITO powder including the process of baking and obtaining an indium tin oxide. The characteristic point is to wash | clean until the resistivity of the supernatant liquid becomes at least 5000 ohm * cm in the said washing | cleaning process, and in the preparation process of the said slurry so that the density | concentration of the said hydroxide particle may be in the range of 1-5 mass%. After diluting the slurry discarding the supernatant with alcohol, an organic protective agent is added to the slurry while stirring in the range of 0.1 to 5% by mass with respect to 100% by mass of the hydroxide particles, and in the firing step, the alcohol is diluted with the alcohol and the Nitrogen gas is circulated in the linear velocity of 0.5-5 m / s in the inside of the tubular furnace which heated the slurry in which the indium tin hydroxide particle which added the organic protecting agent was disperse | distributed to the range of 250-800 degreeC. In this state, by spraying, the indium tin hydroxide particles are thermally decomposed in the tubular furnace and calcined to obtain indium tin oxide particles.

A seventh aspect of the present invention is the invention based on the sixth aspect, wherein the alcohol is ethanol, methanol or propanol, and the organic protecting agent is palmityldimethylethylammoniumethylsulfate, polyvinylalcohol or octyldimethylethylammoniumethylsulphate. It is a manufacturing method of ITO powder which is a pate.

Moreover, 8th viewpoint of this invention is a method of manufacturing a dispersion liquid by disperse | distributing the ITO powder of 1st viewpoint or the ITO powder manufactured by the method in any one of 2nd-7th viewpoint in a solvent.

In addition, a ninth aspect of the present invention is a method of producing an ITO film with the dispersion liquid of the eighth aspect.

The ITO powder of the first aspect of the present invention has a volume resistivity of the green compact when Y is applied at a pressure of 0.196 to 29.42 MPa (2 to 300 kgf / cm 2) to the green compact composed of ITO powder, In the case where the relative density is set to X, the formula (1) is approximated, and since a in the formula (1) is 5.0 × 10 ^-3 or less, and n is -10 or more, this ITO powder is used. The resistivity at the time of forming an ITO film into a coating type can be made low, and high electrical conductivity can be obtained.

Moreover, in the manufacturing method of the ITO powder of the 2nd viewpoint of this invention, in a washing | cleaning process, it wash | cleans until the resistivity of a supernatant liquid becomes at least 5000 ohm * cm, and the density | concentration of hydroxide particle is 10-30 mass in the slurry preparation process. After diluting the slurry which discarded the supernatant so that it may become% of it with water, the organic protective agent is added to the said slurry with stirring in the range of 0.1-5 mass% with respect to 100 mass% of said hydroxide particles, and after baking, ITO powder baked The aggregate of is pulverized and the pulverized ITO powder is impregnated into the surface treatment liquid, and then heated in a nitrogen gas atmosphere in a range 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, contact between the ITO particles is prevented during the firing process, which makes it difficult to grow the particles. This organic protective agent is finally pyrolyzed by firing. Thereby, the surface of an ITO powder is modified, and the resistivity at the time of forming an ITO film into a coating form using this ITO powder can be made low, and high electroconductivity can be obtained.

Moreover, in the manufacturing method of the ITO powder of the 4th viewpoint of this invention, in a washing | cleaning process, it wash | cleans until the resistivity of a supernatant liquid becomes at least 5000 ohm * cm, and the concentration of hydroxide particle is 10-30 mass in the slurry preparation process. After diluting the slurry which discarded the supernatant liquid so that it might become% of water, an organic protective agent is added to the said slurry with stirring in the range of 0.1-5 mass% with respect to 100 mass% of said hydroxide particles, and an organic protective agent is added at a drying process. The slurry in which the indium tin hydroxide is dispersed is dried, and calcined by heating with microwave of 2.45 GHz to 28 GHz in the air in the calcining step, after the calcining step, the aggregate of the calcined ITO powder is pulverized, and the pulverized ITO powder is After impregnation with a surface treatment liquid, it heats in the range of 200-400 degreeC for 0.5 to 5 hours in nitrogen gas atmosphere. Since the hydroxide particles are encapsulated with an organic protective agent having a relatively high decomposition temperature, contact between the ITO particles is prevented during the firing process, which makes it difficult to grow the particles. This organic protective agent is finally pyrolyzed by firing. Thereby, the surface of an ITO powder is modified, and the resistivity at the time of forming an ITO film into a coating form using this ITO powder can be made low, and high electroconductivity can be obtained.

Moreover, in the manufacturing method of the ITO powder of the 6th viewpoint of this invention, in a washing | cleaning process, it wash | cleans until the resistivity of a supernatant liquid becomes at least 5000 ohm * cm, and the density | concentration of hydroxide particle is 1-5 in the preparation process of a slurry. After diluting the slurry which discarded the supernatant so that it may become mass% with alcohol, an organic protective agent is added to the said slurry with stirring in the range of 0.1-5 mass% with respect to 100 mass% of hydroxide particles, and in the said baking process as alcohol Nitrogen gas flows in the linear velocity of 0.5-5 m / s in the inside of the tubular furnace which heated the slurry which diluted the indium tin hydroxide particle which added the organic protective agent to the range of 250-800 degreeC. By spraying, the indium tin hydroxide particles are thermally decomposed in a tubular furnace and calcined to obtain indium tin oxide particles. Since the hydroxide particles are encapsulated with an organic protective agent having a relatively high decomposition temperature, contact between the ITO particles is prevented during the firing process, which makes it difficult to grow the particles. This organic protective agent is finally pyrolyzed by firing. Thereby, the surface of an ITO powder is modified, and the resistivity at the time of forming an ITO film into a coating form using this ITO powder can be made low, and high electroconductivity can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram of the apparatus which measures the resistivity of the green compact of ITO powder.
Fig. 2 is a diagram showing the relationship between the relative density of green compacts of ITO powder and their resistivity.

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 properties of the ITO film made of this ITO powder. In particular, when using an ITO film as a conductive sheet or an electrode, high conductivity, that is, low resistivity is required. The resistivity of this ITO powder is calculated | required by measuring the volume resistivity after making an ITO powder into the form of a green compact. On the other hand, the volume resistivity of the green compact varies with the pressure to be applied. Therefore, the volume resistivity of the green compact at any given pressure is used as a reference. However, depending on the particle size, shape, and agglomeration state of the ITO powder, the packing density changes significantly even at the same pressure, and the resistivity also changes accordingly. For this reason, if the volume resistivity is calculated | required in the state which changed from the low pressure to the high pressure and the relative density of the green compact of ITO powder was changed, and it is made into the resistivity of ITO powder, the more accurate resistivity of ITO powder is calculated | required. The present invention has been made based on this finding.

The ITO powder of the present invention is a surface-modified ITO powder, wherein the volume resistivity of the green compact is Y when a pressure of 0.196 to 29.42 MPa (2 to 300 kgf / cm 2) is applied to the green compact comprising the ITO powder. When the relative density of the green compact is X, the relationship between the volume resistivity and the relative density is approximated by the following formula (1), where a is 5.0 × 10 ^-3 or less in this formula (1), and n is greater than or equal to -10.

Y = aX ⁿ (One)

This formula is derived based on the result of measuring the ITO powder with a low surface resistivity with the surface modification in the green state. When the a exceeds 5.0 × 10 ⁻³ , there is a problem that the conductivity of the coating film is lowered. When n is less than −10, the change in resistance to relative density becomes large, and the conductivity of the film due to spring back of the particles is increased over time. There is a problem that is likely to decrease over time.

The ITO powder used for manufacture of the ITO membrane of this invention is the ITO powder surface-treated by the following three methods. By surface modification, the conductivity of the ITO film produced using this ITO powder can be improved.

(1) First Manufacturing Method

The ITO powder is mixed with an aqueous alkaline solution to a mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound to produce a coprecipitation hydroxide of indium and tin, and the precipitate is dried and calcined, followed by pulverizing the obtained indium tin oxide. Obtained. 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 like. Tin tetrachloride (SnCl) ₄ ) aqueous solution, tin bromide (SnBr ₄ ), and the like. As the alkali aqueous solution, and the like ammonia (NH ₃₎ may, ammonium bicarbonate (NH ₄ HCO ₃₎ can. Indium is adjusted by adjusting the final pH of the reaction solution at the time of coprecipitation of the hydroxide of indium and tin to 3.5 to 9.3, preferably pH 5.0 to 8.0, and the liquid temperature to 5 ° C or higher, preferably to a liquid temperature of 10 ° C to 80 ° C. Coprecipitation hydroxides of and tin can precipitate. Mixing of aqueous alkali solution is performed adding dropwise aqueous alkali solution to the said mixed aqueous solution and adjusting to the said pH range, or performing mixing and mixing the said mixed aqueous solution and aqueous alkali solution to water simultaneously, and adjusting to said pH range.

After formation of the coprecipitation indium tin hydroxide, the precipitate is washed with pure water or ion-exchanged water and washed until the resistivity of the supernatant is at least 5000 Ω · cm, preferably at least 50000 Ω · cm. When the resistivity of the supernatant is lower than 5000 Ω · cm, impurities such as chlorine are not sufficiently removed, and a high purity indium tin oxide powder cannot be obtained. The supernatant liquid of the said precipitate whose resistivity became 5000 ohm * cm or more was discarded, and the slurry with high viscosity in which indium tin hydroxide particle was disperse | distributed is obtained. The slurry is diluted with pure water or ion-exchanged water so that the concentration of the hydroxide particles is in the range of 10 to 30 mass%, preferably 15 to 25 mass%, and then adsorbed onto the surface of the hydroxide particles to improve the dispersibility of the particles. Is added to the slurry with stirring. If the dilution range is less than the lower limit, there is a problem that the drying of the slurry takes time. If the upper limit is exceeded, the organic protective agent is mixed in a state where the viscosity of the slurry is high, resulting in insufficient mixing of the organic protective agent. The addition amount of this organic protective agent is 0.1-5 mass% with respect to 100 mass% of hydroxide particles. It is preferable that the decomposition temperature of an organic protective agent exists in the range of 250-500 degreeC from a viewpoint of suppressing sintering of the ITO powder after thermal decomposition of this organic protective agent. Palmityl dimethyl ethyl ammonium ethyl sulfate, polyvinyl alcohol, or octyl dimethyl ethyl ammonium ethyl sulfate etc. are mentioned as this organic protective agent. When the amount of the organic protective agent added is less than the lower limit of the above range, the surface of the hydroxide particles is not sufficiently protected, and the dispersibility of the particles is inferior. Moreover, when the upper limit is exceeded, there arises a problem that a part of organic matter or carbon powder derived from organic matter remains.

The indium tin hydroxide adsorbed on the surface of the organic protective agent is dried in the air, preferably in an inert gas atmosphere such as nitrogen or argon for 2 to 24 hours in the range of 100 to 200 ° C, and then in the range of 250 to 800 ° C in the air. It is calcined in a baking furnace for 0.5 to 6 hours at. The aggregate formed by this firing is pulverized by using a hammer mill, a ball mill, or the like to obtain ITO powder. After impregnating this ITO powder in the surface treatment liquid which mixed 50-95 mass% anhydrous ethanol and 5-50 mass% distilled water, it is put into a glass chalet and is 0.5-400 to 200-400 degreeC in nitrogen gas atmosphere. When 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 heating firing method are different from the first production method. First, the slurry in which the indium tin hydroxide which added the organic protective agent obtained by the 1st manufacturing method was disperse | distributed is dried. As an example of this drying method, the slurry is pressed into a filter press with a pressure pump to obtain a sludge cake of hydroxide, and the cake is dried. Subsequently, the dried product is heated and fired in the air with microwave of 2.45 GHz to 28 GHz. The microwave heating treatment is performed by, for example, filling the cake with a microwave oven manufactured by Siemshi Technology Development Co., Ltd. and using a 2.45 GHz microwave heating treatment of a micro-reactor manufactured by Shikoku Measuring Industry.

Microwave heating is performed by heating up at a speed | rate which reaches the target temperature within 10 minutes in 250-800 degreeC, Preferably it is 350-600 degreeC, and baking is 5-120 minutes at the target temperature, Preferably it is 10-60. It is carried out by maintaining the range of minutes. If the heating temperature is lower than the lower limit, the hydroxide may not be completely decomposed into oxide. If the heating temperature is exceeded, the ITO particles may be coarsened. If the temperature increase time to the target temperature exceeds 10 minutes, there is a problem that the effect of rapid temperature increase disappears. If the holding time at the target temperature is lower than the lower limit, the hydroxide may not be completely decomposed into an oxide, and if the upper limit is exceeded, the ITO particles may be coarsened. The fired product is pulverized by using a hammer mill, a ball mill, or the like to obtain ITO powder. Hereinafter, the ITO powder surface-modified similarly to the 1st manufacturing method is obtained.

(3) third manufacturing method

The first and second production methods are different in that the indium tin oxide is not pulverized after firing the indium tin hydroxide.

The slurry having a high viscosity in which the indium tin hydroxide particles obtained in the first production method is dispersed is diluted with alcohol so that the concentration of the hydroxide particles is in the range of 1 to 5% by mass, preferably 1 to 3% by mass, and onto the surface of the hydroxide particles. An organic protective agent for adsorbing and improving the dispersibility of these particles is added to the slurry while stirring. The addition amount of this organic protective agent is 0.1-5 mass% with respect to 100 mass% of hydroxide particles. The reason for defining each lower limit and each upper limit of the dilution range and the addition amount range of the organic protective agent is the same as in the first production method. It is preferable that the decomposition temperature of an organic protective agent exists in the range of 250-500 degreeC from a viewpoint of suppressing sintering of the ITO powder after thermal decomposition of this organic protective agent. Examples of the alcohol include ethanol, propanol or methanol, and examples of the organic protective agent include palmityldimethylethylammoniumethylsulfate, polyvinylalcohol or octyldimethylethylammoniumethylsulfate.

Nitrogen which is a carrier gas in the inside of the tubular furnace which heated in the range of 250-800 degreeC which arrange | positioned the slurry which the indium tin hydroxide particle diluted with alcohol and the organic protecting agent was added disperse | distributed perpendicularly to the longitudinal direction of the tube. In a state in which the gas is distributed in the range of 0.5 to 5 m / s linear velocity, it is sprayed using a two-fluid nozzle and introduced into a tubular furnace together with nitrogen gas. If the linear velocity is lower than the lower limit, the amount of ITO powder decreases, and if the upper limit is exceeded, the sprayed slurry is not sufficiently heated. In this way, the indium tin hydroxide particles are thermally decomposed in the tubular furnace and calcined to obtain ITO powder 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.

&Lt; Example 1 >

[Production method of surface modified treatment of ITO powder]

25.4 g of a 55 mass% tin tetrachloride (SnCl ₄ ) aqueous solution was added to 230.7 g of a 24 mass% indium chloride (InCl ₃ ) aqueous solution, followed by stirring to prepare a raw material solution. During the 1000's ㎖ heated to 60 ℃ pure water, the raw material solution and ammonia (NH ₃₎ an aqueous solution of 25 mass% was added dropwise while adjusting the pH at the same time. At this time, the reaction temperature was adjusted to 60 ° C and the pH of the final reaction solution to 5.0. The precipitate which was the produced indium tin coprecipitated hydroxide was repeated with ion-exchange water, and gradient washing was performed. When the resistivity of the supernatant became 5000 Ω · cm or more, the supernatant of the precipitate was discarded to obtain a slurry having a high viscosity in which indium tin hydroxide particles were dispersed.

While stirring this slurry, after diluting this slurry with ion-exchange water so that the density | concentration of hydroxide particle might be 20 mass%, 3.0 g of polyvinyl alcohol which is an organic protective agent was added. The addition amount of this organic protective agent was 2.5 mass% with respect to indium tin hydroxide. After drying this slurry at 110 degreeC for 10 hours in air | atmosphere, it baked at 800 degreeC in air | atmosphere for 3 hours, the aggregate was grind | pulverized, and about 70 g of ITO powder was obtained. 70 g of this ITO powder was added to a surface treatment liquid (mixing ratio of 5% by mass of distilled water relative to 95% by mass of ethanol) in which anhydrous ethanol and distilled water were mixed and impregnated. It heated by time and obtained the surface-modified ITO powder.

[Production of ITO Membrane]

300 parts by mass of ethanol was added to 100 parts by mass of the obtained ITO powder and dispersed in a homogenizer. The obtained coating liquid was apply | coated by the bar coat method on the width 100mm and 50-micrometer-thick PET film, and 50 degreeC warm air was sent and it dried. The thickness of the ITO coating film of the obtained film was 0.2 micrometer. Next, using a roll press machine having a pair of metal rolls having a diameter of 140 mm, the ITO film was compressed at a pressure of 1000 N / mm per unit length in the film width direction and a roll rotational speed of 5 m / min to obtain an ITO membrane. Manufactured.

&Lt; Example 2 >

19.1 g of a 55 mass% tin tetrachloride (SnCl ₄ ) aqueous solution with a concentration of 55 mass% was added to 237.6 g of a 24 mass% indium chloride (InCl ₃ ) aqueous solution, followed by stirring, and then the total amount was added to 1000 ml of pure water. To obtain a raw material liquid. Ammonia (NH ₃₎ an aqueous solution of 25 mass% to the raw material solution was added dropwise over 60 minutes. At this time, 80 degreeC of reaction temperature and pH of the final reaction liquid were adjusted to 8.0. The precipitate which was the produced indium tin coprecipitated hydroxide was repeated with ion-exchange water, and gradient washing was performed. When the resistivity of the supernatant became 5000 Ω · cm or more, the supernatant of the precipitate was discarded to obtain a slurry having a high viscosity in which indium tin hydroxide particles were dispersed. The aqueous solution which melt | dissolved 4.5 g of palmityl dimethyl ethyl ammonium ethyl sulfate (70 mass%) in 100 g of pure water was added to this slurry, and it stirred well. The addition amount of this organic protective agent was 3.0 mass% with respect to indium tin hydroxide.

After drying this slurry at 110 degreeC for 10 hours in air | atmosphere, it baked at 700 degreeC in air | atmosphere for 2 hours, the aggregate was grind | pulverized, and about 75 g of ITO powders were obtained. 75 g of this ITO powder was poured into a surface treatment liquid (mixing ratio of 5% by weight of distilled water relative to 95% by weight of ethanol) in which anhydrous ethanol and distilled water were mixed and impregnated. It heated by time and obtained the surface-modified ITO powder. Using this ITO powder, an ITO film was produced in the same manner as in Example 1.

&Lt; Example 3 >

12.7 g of a 55 mass% tin tetrachloride (SnCl ₄ ) aqueous solution was added to 244.5 g of a 24 mass% indium chloride (InCl ₃ ) aqueous solution, followed by stirring to prepare a raw material solution. During the 1000's ㎖ heated to 60 ℃ pure water, the raw material solution and ammonia (NH ₃₎ an aqueous solution of 25 mass% was added dropwise while adjusting the pH at the same time. At this time, 20 degreeC of reaction temperature and pH of the final reaction liquid were adjusted to 7.0. The precipitate which was the produced indium tin coprecipitated hydroxide was repeated with ion-exchange water, and gradient washing was performed. When the resistivity of the supernatant became 5000 Ω · cm or more, the supernatant of the precipitate was discarded to obtain a slurry having a high viscosity in which indium tin hydroxide particles were dispersed. While stirring this slurry, this slurry was diluted with ethanol so that the concentration of hydroxide particles may be 1.0 mass%, and then 6.0 g of octyldimethylethylammoniumethylsulfate (50 mass%) as an organic protective agent was added to the slurry and stirred well. And the slurry was obtained. The addition amount of this organic protective agent was 3.0 mass% with respect to indium tin hydroxide.

Two-fluid nozzle in the state which distribute | circulates nitrogen gas which is carrier gas in the range of linear velocity of 1 m / s in the inside of the tubular furnace heated at 500 degreeC which arrange | positioned this slurry to the longitudinal direction of the pipe perpendicularly | vertically. Was sprayed and introduced into a tubular furnace with nitrogen gas. In this way, the indium tin hydroxide particles were thermally decomposed in the tubular furnace and calcined to obtain ITO powder subjected to surface modification from the outlet of the tubular furnace. Using this ITO powder, an ITO film was produced in the same manner as in Example 1.

&Lt; Comparative Example 1 &

11.5 g of a 55 mass% tin tetrachloride (SnCl ₄ ) aqueous solution with a concentration of 55 mass% was added to 245 g of a 24 mass% indium chloride (InCl ₃ ) aqueous solution to prepare an InCl ₃ -SnCl ₄ mixed solution. Next, 500 g of ammonium bicarbonate (NH ₄ HCO ₃ ) water was dissolved in ion-exchanged water, and the total amount was prepared at a temperature of 70 ° C. at 1000 mL. The total amount of the InCl ₃ -SnCl ₄ mixed solution was added dropwise to the aqueous solution while stirring for about 20 minutes to form indium tin coprecipitated hydroxide. Again, it stirred for 30 minutes. The final pH of the reaction liquid at this time was 4.5. After recovering the indium tin hydroxide, which was a precipitate, and dewatering with a centrifuge, centrifugal filtration was performed while adding and washing ion-exchanged water, and centrifugal filtration was terminated when the filtrate resistivity reached 5000 Ω · cm or more. . Subsequently, this deposit was dried overnight at 100 degreeC, and then baked at 600 degreeC for 3 hours, the aggregate was pulverized, and 75 g of ITO powders were obtained.

75 g of this ITO powder was poured into a surface treatment liquid (mixing ratio of 5% by weight of distilled water relative to 95% by weight of ethanol) in which anhydrous ethanol and distilled water were mixed and impregnated. It heated by time and obtained the surface-modified ITO powder. Using this ITO powder, an ITO film was produced in the same manner as in Example 1.

&Lt; Comparative Example 2 &

The indium tin hydroxide prepared in the same manner as in Comparative Example 1 was calcined at 1000 ° C for 5 hours, and the same surface treatment as in Comparative Example 1 was performed to obtain 70 g of ITO powder. Moreover, the surface treatment of this ITO powder was performed similarly to the comparative example 1, and the ITO powder was obtained. Using this ITO powder, an ITO membrane was produced in the same manner as in Example 1.

[Evaluation of ITO Powder]

The volume resistivity of each ITO powder obtained in Examples 1-3 and Comparative Example 1 was measured using the measuring apparatus (MCP-PD51 by Mitsubishi Chemical Analytic) shown in FIG. Specifically, the measurement of the volume resistivity of each ITO powder is filled with 2.00 g of ITO powder in the cylinder 1 whose inner diameter phi 25 mm shown in FIG. 1, and 0.196-29.42 MPa (2-300 kgf / cm <2>). The pressure was changed in the range of, and the resistivity and the sample thickness of 10 or more points of ITO powders obtained in Examples 1 to 3 and Comparative Example 1 were measured at the same time. The pressure was measured by the pressure sensor not shown, and the resistivity was measured by the direct current 4-terminal method. In FIG. 1, 2 is a green compact of ITO powder.

The packed mass of the ITO powder which is a sample was divided by the volume calculated | required from the sample thickness, and the internal diameter (phi) of the cylinder, and the actual density was calculated | required, and this real density was divided by theoretical density and it was set as the relative density. 2 shows the relationship between the relative density (horizontal axis) and the volume resistivity (vertical axis) of the green compact of the ITO powder. This relationship is approximated by the following power of expression (1) by the least-squares method. In addition, the volume resistivity of powder is computed by multiplying the measured value by the correction coefficient attached to a measuring system. In Table 1, the value of a and n of the approximation formula (1) obtained by Examples 1-3 and Comparative Examples 1-2 is shown. Y is the volume resistivity of the green compact, and X is the relative density.

Y = aX ⁿ (1)

The surface resistivity (Ω / square) of each ITO membrane obtained in Examples 1-3 and Comparative Examples 1-2 was measured by the resistivity measuring apparatus (MCP-T400 by Mitsubishi Yuka Corporation). Moreover, after 1 day (24 hours) of film-forming, the same measurement was performed and the ratio with the measured value after film-forming was computed. The results are shown in Table 1.

As apparent from Table 1, the surface resistivity of the ITO film made of the ITO powder of Examples 1 to 3 in which a in the formula (1) is 5.0 × 10 ⁻³ or less and n is −10 or more is 1.0 × 10 ⁴ Ω / □ Or less. In contrast, the surface resistivity of the ITO film made of the ITO powder of Comparative Example 1 in which a in Formula (1) exceeded 5.0 × 10 ⁻³ exceeded 1.0 × 10 ⁴ Ω / □. In addition, the surface resistivity of the ITO film | membrane made from ITO powder whose n of the comparative example 2 is less than -10 exceeded 1.0x10 <^{4> (} ohm) / square, and the surface resistivity after one day of film-forming exceeded 1.7 times and 1.5 times. In this respect, Examples 1 to 3 having a relationship approximating Equation (1) proved to have high electrical conductivity by lowering the resistivity when forming an ITO film by coating.

Claims

As surface modified ITO powder,
When the volume resistivity of the green compact at the time of applying a pressure of 0.196 to 29.42 MPa to the green compact composed of the ITO powder is Y and the relative density of the green compact is X, the relationship between the volume resistivity and the relative density is It approximates to following formula (1), In this formula (1), a is 5.0 * 10 <^-3> or less, and n is -10 or more, ITO powder characterized by the above-mentioned.
Y = aX ⁿ (One)

Mixing an aqueous alkali solution with a mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound to produce a coprecipitation hydroxide of indium and tin, washing the coprecipitation hydroxide with pure water or ion-exchanged water, and the coprecipitation hydroxide A method for producing an ITO powder comprising a step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding the supernatant, a step of drying the slurry, and a step of firing the dried indium tin oxide to obtain indium tin oxide. In
In the washing step, washing is performed until the resistivity of the supernatant is at least 5000 Ω · cm,
In the slurry preparation step, after diluting the slurry discarding the supernatant with water so that the concentration of the hydroxide particles is in the range of 10 to 30 mass%, an organic protective agent is added to the slurry to 0.1 to 5 mass% of the hydroxide particles. It is added with stirring in the range of mass%, and after the said baking process, the aggregate of the calcined ITO powder was grind | pulverized, and this pulverized ITO powder was impregnated in the surface treatment liquid, and it is the range of 200-400 degreeC under nitrogen gas atmosphere. It heats for 0.5 to 5 hours at the manufacturing method of the ITO powder of Claim 1 characterized by the above-mentioned.

3. The method of claim 2,
A process for producing ITO powder, wherein the organic protecting agent is palmityldimethylethylammoniumethylsulfate, polyvinylalcohol or octyldimethylethylammoniumethylsulfate.

Mixing an aqueous alkali solution with a mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound to produce a coprecipitation hydroxide of indium and tin, washing the coprecipitation hydroxide with pure water or ion-exchanged water, and the coprecipitation hydroxide A method for producing an ITO powder comprising a step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding the supernatant, a step of drying the slurry, and a step of firing the dried indium tin oxide to obtain indium tin oxide. In
In the washing step, washing is performed until the resistivity of the supernatant is at least 5000 Ω · cm,
In the slurry preparation step, after diluting the slurry discarding the supernatant with water so that the concentration of the hydroxide particles is in the range of 10 to 30 mass%, an organic protective agent is added to the slurry to 0.1 to 5 mass% of the hydroxide particles. It is added, stirring in the range of mass%,
In the drying step, the slurry in which the indium tin hydroxide to which the organic protective agent is added is dispersed is dried,
In the firing step, heating and firing is carried out in the air with a microwave of 2.45 GHz to 28 GHz,
After the said baking process, the aggregate of the baked ITO powder is grind | pulverized, and this pulverized ITO powder is impregnated in surface treatment liquid, and it heats for 0.5 to 5 hours in 200-400 degreeC under nitrogen gas atmosphere, It is characterized by the above-mentioned. The manufacturing method of the ITO powder of Claim 1.

5. The method of claim 4,
The said organic protective agent is palmityl dimethyl ethyl ammonium ethyl sulfate, polyvinyl alcohol, or octyl dimethyl ethyl ammonium ethyl sulfate, The manufacturing method of the ITO powder.

Mixing an aqueous alkali solution with a mixed aqueous solution of a trivalent indium compound and a tetravalent tin compound to produce a coprecipitation hydroxide of indium and tin, washing the coprecipitation hydroxide with pure water or ion-exchanged water, and the coprecipitation hydroxide A method for producing an ITO powder comprising a step of preparing a slurry in which indium tin hydroxide particles are dispersed by discarding the supernatant, a step of drying the slurry, and a step of firing the dried indium tin oxide to obtain indium tin oxide. In
In the washing step, washing is performed until the resistivity of the supernatant is at least 5000 Ω · cm,
In the preparation step of the slurry, after diluting the slurry discarding the supernatant with alcohol so that the concentration of the hydroxide particles is in the range of 1 to 5% by mass, an organic protective agent is added to the slurry to 0.1 to 100% by mass of the hydroxide particles. It is added, stirring in the range of 5 mass%,
In the firing step, nitrogen gas is added to a linear velocity of 0.5 to 5 m in a tubular furnace in which a slurry in which indium tin hydroxide particles are diluted with the alcohol and to which the organic protecting agent is added is heated in a range of 250 to 800 ° C. The method for producing the ITO powder according to claim 1, wherein the indium tin hydroxide particles are thermally decomposed and fired in the tubular furnace by spraying in a state of circulating in the range of / s to obtain indium tin oxide particles.

The method according to claim 6,
The said alcohol is ethanol, methanol, or a propanol, and the said organic protective agent is palmityl dimethyl ethyl ammonium ethyl sulfate, polyvinyl alcohol, or octyl dimethyl ethyl ammonium ethyl sulfate, The manufacturing method of the ITO powder.

A method for producing a dispersion by dispersing the ITO powder according to claim 1 or the ITO powder produced by the method according to any one of claims 2 to 7 in a solvent.

A method for producing an ITO membrane with the dispersion according to claim 8.