JP4240905B2 - Indium-based oxide fine particles and production method thereof, coating liquid for forming transparent conductive film containing indium-based oxide fine particles, substrate with transparent conductive film, and display device - Google Patents

Description

【図面の簡単な説明】
【図１】実施例１で製造された本発明に係るインジウム系酸化物微粒子のＸ線回折パターンを示す。
【図２】比較例１で製造された従来のインジウム系酸化物微粒子のＸ線回折パターンを示す。
【図３】比較例２で製造された従来のインジウム系酸化物微粒子のＸ線回折パターンを示す。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an indium oxide fine particle dispersed sol having a novel X-ray diffraction pattern, a method for producing the same, a coating liquid for forming a transparent conductive film containing indium oxide fine particles, a substrate with a transparent conductive film, a display Relates to the device.
More specifically, the indium-based oxide fine particles are stable and monodispersed sols without being agglomerated, sintered, or fused to each other, and the resulting coating liquid for forming a transparent conductive film is stable. , An indium oxide fine particle dispersed sol that can be suitably used for a substrate with a transparent conductive film excellent in film strength, appearance, production reliability, and the like, a method for producing the same, and a transparent conductive material containing the fine particles The present invention relates to a coating liquid for forming a film, a substrate with a transparent conductive film, and a display device.
[0002]
TECHNICAL BACKGROUND OF THE INVENTION
Conventionally, transparent coatings having antistatic and antireflection functions on the surfaces of transparent substrates such as cathode ray tubes, fluorescent display tubes, and liquid crystal display panels, for the purpose of antistatic and antireflection. It was done to form.
Further, it is known that electromagnetic waves are emitted from a cathode ray tube or the like, and in addition to conventional antistatic and antireflection, it is desired to shield these electromagnetic waves and the electromagnetic field formed with the emission of electromagnetic waves. .
[0003]
One method of shielding these electromagnetic waves and the like is a method of forming a conductive film for shielding electromagnetic waves on the surface of a display panel such as a cathode ray tube. If it is a conductive film for antistatic, the surface resistance is at least 10⁸While it is sufficient to have a surface resistance of about Ω / □, it is 10 for a conductive coating for electromagnetic shielding.²-10^FourIt was necessary to have a low surface resistance such as Ω / □.
[0004]
Also known is a method of forming a metal fine particle-containing film on the surface of a base material using a conductive film forming coating solution containing metal fine particles such as Ag as a low surface resistance conductive film. In this method, a coating solution in which colloidal metal fine particles are dispersed in a polar solvent is used as a coating solution for forming a coating containing metal fine particles. In such a coating solution, in order to improve the dispersibility of the colloidal metal fine particles, the surface of the metal fine particles is surface-treated with an organic stabilizer such as polyvinyl alcohol, polyvinyl pyrrolidone or gelatin. However, a conductive coating formed using such a coating solution for forming a coating containing metal fine particles has a large intergranular resistance because the metal fine particles come into contact with each other through a stabilizer in the coating. Sometimes did not go down. For this reason, after film formation, it is necessary to decompose and remove the stabilizer by baking at a high temperature of about 400 ° C. However, when the baking is carried out at a high temperature to decompose and remove the stabilizer, fusion and aggregation of metal fine particles occur. There is a problem that the transparency and haze of the conductive film are lowered. In the case of a cathode ray tube or the like, there is a problem that the cathode ray tube deteriorates when exposed to a high temperature.
[0005]
In addition, unlike the conductive oxide, the metal fine particles do not originally transmit light, so the conductive film formed using the metal fine particles is transparent depending on the density and film thickness of the metal fine particles in the conductive film. There was also a problem of lowering.
Furthermore, in the conventional transparent conductive film containing fine metal particles such as Ag, salt water resistance and oxidation resistance are low, the metal is oxidized, particle growth due to ionization, and in some cases, corrosion may occur, There was a problem that the conductivity and light transmittance of the coating film were lowered, and the display device lacked reliability.
[0006]
In addition, the coating liquid used for forming the above-described conventional transparent conductive film, particularly, highly conductive fine particles such as metal fine particles to form a low surface resistance transparent conductive film excellent in electromagnetic wave shielding performance. The coating solution containing the above has insufficient stability, and the surface of the obtained transparent conductive film is not necessarily smooth, and may cause streak or spot-like appearance defects, thus reducing the product yield. There was a problem. Further, when a conventional coating solution is used, there is a problem that defects in appearance are easily derived under the influence of the cleanliness of the substrate and the manufacturing reliability is lacking.
[0007]
Attempts have also been made to use a coating solution containing a conductive oxide such as Sb-doped tin oxide or Sn-doped indium oxide instead of metal fine particles. Such conductive oxide particles are prepared by hydrolyzing an aqueous solution of a tin compound, a tin compound containing an Sb compound, an indium compound, an indium compound containing a tin compound, and the like, and then drying the hydrolyzate. It was manufactured by firing at a high temperature (Japanese Patent Laid-Open No. 63-11519). In such a method, the conductive oxide fine particles are obtained as aggregates, and the particle size distribution is not uniform. For this reason, an agglomerate is pulverized in an acid aqueous solution or an alkali aqueous solution to form an aqueous sol in which conductive oxide fine particles are dispersed in water as colloidal particles (Japanese Patent Laid-Open No. Sho 62-230617).
[0008]
Since such a conductive oxide generally has a higher conductive resistance than a metal, it has been necessary to make the film thickness thicker than in the case of a metal antistatic coating. However, since the antireflection effect is not manifested unless the film thickness of the conductive film is about 10 to 200 nm, the conventional conductive oxide such as Sb-doped tin oxide or Sn-doped indium oxide has a low surface resistance, There was a problem that it was difficult to obtain a conductive film that was excellent in electromagnetic wave shielding properties and also in antireflection.
[0009]
OBJECT OF THE INVENTION
The present invention solves the problems of the prior art as described above, and is excellent in antistatic properties, antireflection properties, electromagnetic shielding properties, etc., and in forming a transparent conductive film excellent in film strength and transparency. It is an object of the present invention to provide indium oxide fine particles that can be used, a method for producing the fine particles, a coating liquid for forming a transparent conductive film, a substrate with a transparent conductive film, and a display device comprising the fine particles.
[0010]
SUMMARY OF THE INVENTION
  The indium-based oxide fine particles according to the present invention have, in the X-ray diffraction pattern, at least a peak in the plane index (2, 2, 2) attributed to indium oxide (P_A) And the peak in the plane index (2, 0, 0) attributed to indium hydroxide (P_B1), Peak in the plane index (2, 2, 0) (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) Ratio (HP)_B2) / (HP_A) Is 1/2 or less,
  Indium oxide, S n Or indium oxide doped with FIt is characterized by that.
[0011]
  As for the fine particles, the electric conductivity of a sol in which the indium oxide fine particles described above are dispersed in a dispersion medium in which the ratio of water in the dispersion medium is 80% by weight or more is 4% by weight as an oxide. Is preferably 100 μS / cm or less.
  The method for producing the indium oxide fine particles includes the following steps:
(A)Indium hydroxide or indium hydroxide containing tin or fluorinePreparing an organic solvent dispersion of indium hydroxide,
(B) The organic solvent dispersion in a temperature range of 120 to 400 ° C.In a pressure vesselHeat treatment process.
[0012]
  In addition, the indium oxide fine particles can be produced from the following steps;
(A ')Indium hydroxide or indium hydroxide containing tin or fluorineWith indium hydroxide, Indium oxide, S n Or indium oxide doped with FPreparing an organic solvent mixed dispersion with indium oxide seed particles,
(B)Obtained organic solvent dispersionIn the temperature range of 120-400 ° CIn a pressure vesselHeat treatment process.
[0013]
Dehydration or substitution with another organic solvent, and further heat treatment in a temperature range of 120 to 400 ° C., and / or
Deionizing
May be applied.
The coating liquid for forming a transparent conductive film according to the present invention is characterized in that it contains the indium oxide fine particles and a polar solvent.
[0014]
The substrate with a transparent conductive film according to the present invention is
A base material, a transparent conductive fine particle layer containing the indium-based oxide fine particles on the base material, and a transparent film provided on the transparent conductive fine particle layer and having a refractive index lower than that of the transparent conductive fine particle layer It is characterized by becoming.
A display device according to the present invention includes:
A front plate made of the substrate with a transparent conductive film is provided, and the transparent conductive film is formed on the outer surface of the front plate.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described.
Indium oxide fine particles
The indium-based oxide fine particles according to the present invention have X-ray crystallinity, and in the X-ray diffraction pattern, at least a peak in the plane index (2, 2, 2) attributed to indium oxide (P_A) And the peak in the plane index (2, 0, 0) attributed to indium hydroxide (P_B1), Peak in the plane index (2, 2, 0) (P_B2)
Peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) Ratio (HP)_B2) / (HP_A) Is ½ or less, preferably ¼ or less.
[0016]
FIG. 1 shows an X-ray diffraction pattern of such an indium oxide fine particle according to the present invention. FIG. 1 is an X-ray diffraction pattern of tin-containing indium oxide fine particles obtained in Example 1 described later.
The peak ratio (HP_B2) / (HP_A) Exceeds 1/2, there is too much indium hydroxide, and sufficient conductivity cannot be obtained. In addition, the peak (P_B2It is difficult to obtain indium-based oxide fine particles without (indium hydroxide).
[0017]
Such indium oxide fine particles preferably have an average particle diameter in the range of 2 to 200 nm, preferably 5 to 150 nm.
When the average particle diameter of the indium-based oxide fine particles is less than the lower limit, the grain boundary resistance increases, the surface resistance of the particle layer increases rapidly, and the resistance value is low enough to achieve the object of the present invention. A film may not be obtained.
[0018]
If the average particle size of the indium oxide fine particles exceeds the above upper limit, the particles are too large, the contact between the particles may decrease, and sufficient conductivity may not be obtained, and film strength and adhesion to the substrate may be obtained. May decrease or the haze of the transparent conductive film obtained may increase.
In addition, the average particle diameter of the indium oxide fine particles of the present invention can be obtained as an average particle diameter by taking a TEM photograph and measuring the particle diameter of 20 particles.
[0019]
As the indium oxide fine particles, indium oxide, indium oxide doped with Sn or F is used. In this case, the Sn or F content is in the range of 1 to 14% by weight, preferably 2 to 12% by weight.
Such indium-based oxide fine particles have high conductivity among the oxide-based conductive fine particles, and the obtained transparent conductive film is excellent in antistatic performance and electromagnetic wave shielding performance, and has a transparent conductive film using metal fine particles. Unlikely, it has excellent transparency.
[0020]
The indium oxide fine particles according to the present invention can be used as a powder as it is, but can also be used as a dispersed sol dispersed in water and / or an organic solvent.
Organic solvents include methanol, ethanol, propanol, butanol, diacetone alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, alcohols such as ethylene glycol, hexylene glycol, and isopropyl glycol; esters such as acetic acid methyl ester and acetic acid ethyl ester Ethers such as diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone, acetylacetone and acetoacetate It is done. These may be used singly or in combination of two or more.
[0021]
The concentration of the indium oxide fine particles in the dispersed sol is preferably in the range of 1 to 50% by weight, more preferably 2 to 40% by weight as an oxide.
When the indium oxide fine particle concentration is less than the lower limit as an oxide, for example, when used in a coating solution for forming a transparent conductive film, the concentration of the resulting coating solution is low. However, it is difficult to form a coating film, and therefore, a plurality of times of application, drying, and the like are required.
[0022]
It is difficult to obtain an oxide having an indium oxide fine particle concentration exceeding the above upper limit as an oxide, and it is not necessary to increase the concentration to this concentration practically.
The indium-based oxide fine particles according to the present invention are dispersed in a dispersion medium having a water ratio of 80% by weight or more so that the electric conductivity is low and the concentration as an oxide is 4% by weight. The electric conductivity of the dispersed sol is desirably 100 μS / cm or less, and more desirably 50 μS / cm or less.
[0023]
If the electrical conductivity is within the above range, the dispersion sol in which the indium oxide fine particles are dispersed has high stability. Therefore, the transparent sol described later is obtained by blending such an indium oxide fine particle dispersion sol. The coating liquid for forming the conductive film is also highly stable, and it is possible to obtain a film having excellent adhesion to the base material, film strength and transparency, and there is no occurrence of unevenness in the obtained film. A film having a good appearance can be obtained.
[0024]
Method for producing indium oxide fine particles
The manufacturing method of the indium oxide fine particles according to the present invention includes the following steps.
Step (a)
First, an organic solvent dispersion of indium hydroxide or indium hydroxide containing tin or fluorine (hereinafter referred to as indium hydroxide dispersion) is prepared.
[0025]
The indium hydroxide may be prepared by dispersing it in an organic solvent as long as it is available as a hydroxide.
As the organic solvent, the same organic solvent as that used in the sol can be used. The dispersion medium is preferably an organic solvent alone (that is, containing no water), but may contain a small amount of water as necessary.
[0026]
Further, in the present invention, an indium compound aqueous solution and, if necessary, an tin and / or fluorine compound aqueous solution are used as follows, without directly dispersing the hydroxide, and the contained indium compound is hydrolyzed and necessary. It is preferable to use a dispersion liquid in which an indium hydroxide obtained by washing is dispersed in an organic solvent.
The indium compound is not particularly limited as long as it is a water-soluble compound, and examples thereof include indium nitrate, indium sulfate, and indium chloride.
[0027]
The concentration of the indium compound aqueous solution depends on the oxide In₂O_ThreeIs preferably in the range of 1 to 20% by weight, more preferably 4 to 10% by weight.
Concentration of indium compound aqueous solution is oxide In₂O_ThreeWhen the concentration is less than 1% by weight, the production efficiency is low because the concentration is low, and the concentration of the indium compound aqueous solution is the oxide In.₂O_ThreeIf it exceeds 20% by weight, the particle size distribution of the indium oxide fine particles finally obtained tends to be broad, that is, the particle size tends to be non-uniform.
[0028]
Examples of the tin compound include potassium stannate, sodium stannate, tin fluoride, tin chloride and the like. Examples of the fluorine compound include tin fluoride and ammonium fluoride.
The amount of the tin compound aqueous solution and / or the fluorine compound aqueous solution to be mixed with the indium compound aqueous solution may be an amount such that the Sn and / or F content in the obtained indium oxide fine particles falls within the above-described range.
[0029]
Further, an aqueous solution of NaOH, KOH, RbOH, CsOH or the like can be used as the aqueous alkali metal hydroxide solution to be mixed in order to adjust the pH of the indium hydrate dispersion obtained by mixing to the range described later.
An indium compound aqueous solution and, if necessary, a tin compound aqueous solution and / or a fluorine compound aqueous solution are mixed with an alkali metal hydroxide aqueous solution as necessary to contain indium hydroxide or tin and / or fluorine. An indium hydroxide dispersion is prepared.
[0030]
The temperature of the indium hydroxide dispersion at this time is preferably in the range of 20 to 80 ° C, more preferably 25 to 60 ° C. The pH of the dispersion is preferably in the range of 8 to 12, more preferably 9 to 11.5.
When the temperature of the dispersion is lower than the lower limit, the indium oxide fine particles finally obtained tend to be aggregates because the particle diameter of indium hydroxide is small.
[0031]
When the temperature of the dispersion exceeds the above upper limit, indium hydroxide having a non-uniform size is generated, and the particle diameter of the resulting indium oxide fine particles tends to be non-uniform.
In addition, when the pH of the dispersion is less than the lower limit, indium hydroxide with non-uniform size is generated as in the case where the temperature is high, and the particle size of the resulting indium oxide fine particles is non-uniform. Tend to be. Further, if the pH of the dispersion exceeds the above upper limit, it becomes difficult to easily remove alkali even by washing, the residual amount of alkali metal in the indium oxide fine particles increases, and the conductivity becomes insufficient. Sometimes.
[0032]
Next, the obtained indium hydroxide dispersion may be aged in the above temperature and pH range, if necessary. During the aging, it may be stirred or may not be stirred. The aging time at this time varies depending on the temperature and pH, but is about 0.2 to 24 hours.
Indium hydroxide is dispersed in the form of fine particles in the indium hydroxide dispersion thus obtained without agglomeration.
[0033]
By performing such aging, the particle size distribution of the finally obtained indium-based oxide fine particles tends to be uniform.
Subsequently, the indium hydroxide dispersion may be separated by filtration and washed as necessary. The washing method is not particularly limited as long as it can remove cations and anions derived from alkali metals and / or indium compounds, and a conventionally known method can be employed. For example, it may be cleaned using warm water sufficiently, or may be cleaned using ammonia water or acid. Furthermore, it can also deionize (cation and anion) with an ion exchange resin as needed.
[0034]
The remaining amount of alkali metal after washing is M₂O (M: alkali metal cation) is preferably 0.01% by weight or less, more preferably 0.001% by weight or less.
If the remaining amount of alkali metal exceeds the above upper limit, the resulting fine particles have insufficient conductivity, or if a dispersion of indium oxide fine particles is prepared, the stability of the dispersion is low and the particles aggregate. Sometimes.
[0035]
Further, the remaining amount of the anion after washing is preferably 0.01% by weight or less, and more preferably 0.001% by weight or less. If the remaining amount of anions exceeds the above upper limit, when a dispersion of indium oxide fine particles is prepared, the stability of the dispersion is low and the particles may aggregate.
The indium hydroxide after washing is dispersed in an organic solvent to prepare an organic solvent dispersion. At this time, it is preferable to replace the solvent with an organic solvent as necessary so that the remaining amount of water in the dispersion is approximately 10% by weight or less. If the remaining amount of water in the dispersion exceeds 10% by weight, indium-based oxide fine particles having the X-ray diffraction pattern as described above cannot be obtained, that is, an indium-based oxide with a small proportion of indium-based hydroxide. Fine particles cannot be obtained, and the transparent conductive film obtained by using such indium-based oxide fine particles does not exhibit sufficient conductivity and may not provide sufficient antistatic performance.
[0036]
As the organic solvent, the same ones as described above are used. An organic solvent may be used independently and may be used in mixture of 2 or more types. The dispersion medium is preferably only an organic solvent, but may contain a small amount of water as necessary.
In particular, when using alcohols such as methanol, ethanol, propanol, butanol, diacetone alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, hexylene glycol, isopropyl glycol, oxides of indium oxide fine particles obtained Of the above-mentioned peak ratio (HP_B2) / (HP_A) Is 1/4 or less and indium oxide fine particles having a high ratio of indium oxide are obtained, and further, monodispersed indium oxide fine particle-dispersed sol without aggregation is obtained.
[0037]
The concentration of the organic solvent dispersion of the indium hydroxide is preferably in the range of 1.0 to 20% by weight, more preferably 3 to 10% by weight as an oxide.
When the concentration of the indium hydroxide dispersion is less than the lower limit as an oxide, the concentration is too low to cause particle growth, and the yield and production efficiency are further reduced.
If the concentration of the organic solvent dispersion of the indium hydroxide exceeds the above upper limit as an oxide, the dispersion of the indium hydroxide will not be uniform, so the particle size distribution of the resulting indium oxide fine particles will be non-uniform It may become.
[0038]
  Seed particles
  In the present invention, an indium-based hydroxide is dispersed in an organic solvent dispersion of indium-based hydroxide.OxideSeed particles may be included. When seed particles are contained in this way, indium hydroxide particles having a uniform particle diameter can be obtained, and indium oxide can be obtained by adjusting the mixing ratio of seed particles and hydroxide. The particle diameter of the product fine particles can be controlled.
[0039]
As the indium-based oxide seed particles, water and / or organic solvent dispersions of seed particles made of indium oxide doped with indium oxide, tin and / or fluorine are used. As the organic solvent at this time, the same organic solvent as described above can be used. The size of such seed particles is not particularly limited, but those in the range of 2 to 100 nm are preferably used.
[0040]
The seed particles made of indium oxide doped with indium oxide, tin and / or fluorine used are not particularly limited, and for example, commercially available powders can be used without particular limitation. Moreover, it can also grind | pulverize and use until it becomes a desired average particle diameter.
The seed particles may have the same composition as the oxide derived from the indium hydroxide used, or a different composition, for example, the seed particles are indium oxide and the indium hydroxide is tin. And / or indium hydroxide containing fluorine.
[0041]
In particular, in the present invention, as the seed particles made of indium oxide doped with indium oxide, tin and / or fluorine, indium oxide fine particles produced by the method according to the present invention are suitable. In particular, when a dispersed sol containing these particles is used, indium oxide fine particles having a uniform particle diameter can be prepared.
The concentration of the mixed dispersion of the indium hydroxide dispersion and the indium oxide seed particles is preferably in the range of 1 to 20% by weight, more preferably 4 to 10% by weight as the oxide including the hydroxide. .
[0042]
When the concentration of the mixed dispersion is less than 1% by weight as an oxide, the indium hydroxide is not effectively deposited on the indium oxide seed particles, and it is difficult to obtain larger indium oxide fine particles. When the concentration of the mixed dispersion exceeds 20% by weight as an oxide, indium hydroxides form new particles, or indium hydroxides deposited and deposited on indium oxide seed particles are uneven. For this reason, the particle diameter of the indium oxide fine particles obtained tends to be non-uniform.
[0043]
In addition, the mixing ratio of the indium oxide seed particles and the indium hydroxide dispersion is such that the oxide derived from the indium oxide seed particle dispersion sol is MO._ZAnd the oxide derived from the indium hydroxide dispersion is MO_GWhen MO_G/ MO_ZIs preferably in the range of 0.5 to 500, more preferably 1 to 100.
This mixing ratio MO_G/ MO_ZIs less than 0.5, the efficiency of enlarging the particles is low, and the mixing ratio MO_G/ MO_ZExceeds 500, the indium hydroxide forms new particles, or the indium hydroxide deposited and deposited on the indium oxide fine particles becomes non-uniform. The particle diameter tends to be non-uniform. In the present invention, the MO_G/ MO_ZBy changing the mixing ratio in the range of 0.5 to 500, the particle size of the indium oxide fine particles can be controlled.
Step (b)
Next, an organic solvent dispersion of indium hydroxide or a mixed dispersion of indium hydroxide organic solvent dispersion containing indium oxide seed particles is used at a temperature of 120 to 400 ° C., preferably 150 to 250 ° C. Heat treatment. In addition, when heating at the temperature more than the boiling point of the solvent under atmospheric pressure, you may heat in a pressurized state using pressure-resistant containers, such as an autoclave.
[0044]
When the heat treatment temperature is less than 120 ° C., indium oxide fine particles with a small proportion of indium hydroxide or a large proportion of indium oxide as in the case where the organic solvent dispersion has a large amount of water. May not be obtained.
When the heat treatment temperature exceeds 400 ° C., there is no organic solvent that can be suitably used, and aggregated particles are formed although the proportion of the indium oxide is high.
[0045]
By performing the steps (a) and (b) as described above, the indium oxide fine particles according to the present invention as described above can be obtained.
Thus, when heat-treated in a specific organic solvent, indium-based oxide fine particles having a uniform particle size and excellent dispersibility can be obtained. The reason why such fine particles can be obtained is not clear, but in organic solvents, the presence of organic solvents on the surface of the particles prevents aggregation and bonding between particles, and heat treatment is performed in an organic solvent with little water. Therefore, the dehydration reaction easily proceeds, and it is considered that monodispersed indium oxide fine particles mainly composed of oxides can be obtained.
[0046]
In the conventional method, the indium hydroxide is dried, fired and pulverized to prepare indium oxide fine particles. In this method, it is necessary to calcinate at a high temperature and, after firing, pulverize in the presence of an acid or an alkali, and it is difficult to obtain indium oxide fine particles having a uniform particle size.
However, according to the present invention, an indium oxide fine particle-dispersed sol that is stably monodispersed by merely heat-treating a sol in which an indium hydroxide is dispersed in an organic solvent, and a method for producing the same are provided.
[0047]
The indium oxide fine particles thus obtained are used after drying to remove the solvent. It can also be used in the form of a dispersed sol dispersed in a dispersion medium (organic solvent).
Further, if necessary, the following steps (c) and / or (d) may be performed.
Process (c) :Heat treatment
The dispersion of fine particles obtained in the step (b) is dehydrated or substituted with an organic solvent by an ultrafiltration membrane method or a rotary evaporator as necessary, and again at 120 to 400 ° C, preferably 150 to 250 ° C. You may heat-process in a temperature range. When heating at a temperature equal to or higher than the boiling point of the solvent under atmospheric pressure, a pressure vessel such as an autoclave may be used and heated under pressure.
[0048]
After the step (b), water is desorbed as the indium hydroxide becomes indium oxide. Therefore, the peak ratio (HP_B2) / (HP_A) Is not reduced to ½ or less, it is preferable to remove and dehydrate the desorbed water or replace it with an organic solvent, and heat treatment again.
Process (d) :Desalting treatment
As a method for desalting, the concentration of salts (including cations and anions) in the indium oxide fine particle-dispersed sol can be reduced, and the electric conductivity of the sol is set to 100 μS / cm or less, more preferably 50 μS / cm or less. If possible, there is no particular limitation, and examples thereof include a method of deionizing with an ion exchange resin, an ultrafiltration membrane cleaning method, and a decantation method.
[0049]
If the electric conductivity of the indium oxide fine particle dispersed sol is 100 μS / cm or less, the stability of the dispersed sol in which the indium oxide fine particles are dispersed is improved, and the indium oxide fine particle dispersed sol described later is used. The stability of the resulting coating liquid for forming a transparent conductive film is also improved, and the film obtained using such a coating liquid is excellent in adhesion to a substrate, film strength, transparency, and the like.
[0050]
It is desirable that the average particle diameter of the indium oxide fine particles in the indium oxide fine particle dispersed sol thus obtained is in the range of approximately 2 to 200 nm, more preferably 5 to 150 nm.
Coating liquid for forming transparent conductive film
Next, the coating liquid for forming a transparent conductive film according to the present invention will be described.
[0051]
The coating liquid for forming a transparent conductive film according to the present invention comprises the indium oxide fine particles as conductive fine particles and a polar solvent.
Polar solvents include water, methanol, ethanol, propanol, butanol, diacetone alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, alcohols such as ethylene glycol, hexylene glycol, isopropyl glycol; acetic acid methyl ester, acetic acid ethyl ester, etc. Esters such as diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether and diethylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone, acetylacetone and acetoacetate Is mentioned. These may be used singly or in combination of two or more.
[0052]
In the coating liquid for forming a transparent conductive film, it is desirable that indium oxide fine particles are contained in the range of 0.1 to 7% by weight, preferably 0.5 to 5% by weight as an oxide.
When the indium oxide fine particles in the coating liquid for forming a transparent conductive film is less than the lower limit, the film thickness of the obtained film may be thin, and thus sufficient conductivity may not be obtained. If the indium oxide fine particles exceed the above upper limit, the indium oxide fine particles may form secondary particles (aggregated particles or non-monodispersed particles connected in a chain) in the coating solution. If the amount of secondary particles is increased, the adhesion to the substrate and the denseness of the film may be lowered, the film strength may be lowered, and sufficient conductivity may not be obtained. Furthermore, the film may be thick, the light transmittance may be reduced to deteriorate the transparency, or the flatness of the film surface may be reduced to cause streaks, unevenness, etc., resulting in a poor appearance.
[0053]
In addition to the indium oxide fine particles, the coating liquid for forming a transparent conductive film of the present invention includes Au, Ag, Pd, Pt, Rh, Ru, Cu, Fe, Ni, Co, Sn, Ti, In, Al, Metal fine particles composed of at least one selected from metals such as Ta and Sb, or composite metal fine particles composed of two or more metals (sometimes collectively referred to as metal fine particles) may be included.
[0054]
Preferred combinations of two or more metals include Au-Cu, Ag-Pt, Ag-Pd, Au-Pd, Au-Rh, Pt-Pd, Pt-Rh, Fe-Ni, Ni-Pd, and Fe-Co. , Cu-Co, Ru-Ag, In-Sn, Au-Cu-Ag, Ag-Cu-Pt, Ag-Cu-Pd, Ag-Au-Pd, Au-Rh-Pd, Ag-Pt-Pd, Ag -Pt-Rh, Fe-Ni-Pd, Fe-Co-Pd, Cu-Co-Pd and the like.
[0055]
Such metal fine particles may be contained in an amount that does not impair the object of the present invention, and the content thereof is not particularly limited. For example, in the coating liquid for forming a transparent conductive film, 30 wt. % Or less, preferably 10% by weight or less.
When such metal fine particles are contained, the conductivity of the conductive coating is improved and the electromagnetic wave shielding ability is improved, and in addition, the transmittance can be controlled by using the metal fine particles. In addition, when the metal fine particles and the indium oxide fine particles according to the present invention are used in combination, the salt water resistance, oxidation resistance and the like are excellent as compared with the case of using only the metal fine particles.
[0056]
Further, when the metal fine particles are mixed and used in this way, an organic stabilizer may be included in the coating liquid for forming a transparent conductive film in order to improve the dispersibility of the metal fine particles. Specific examples of such organic stabilizers include gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, and citric acid. And the like, and heterocyclic compounds or mixtures thereof such as polyvalent carboxylic acids and salts thereof, acetylacetone or mixtures thereof.
[0057]
Further, the coating liquid for forming a transparent conductive film of the present invention preferably contains fine particle carbon and / or titanium black as a colorant. Furthermore, dyes and pigments may be included. When such a colorant is contained, a display device having excellent contrast can be obtained.
The coating liquid for forming a transparent conductive film according to the present invention may contain a matrix forming component component that acts as a binder for the indium oxide fine particles after the film is formed. Such a matrix-forming component is preferably composed of silica. Specifically, silicic acid obtained by dealkalizing a hydrolyzed polycondensate of an organosilicon compound such as alkoxysilane or an aqueous alkali metal silicate solution. Examples thereof include polycondensates and paint resins. This matrix-forming component may be contained in an amount of 0.01 to 0.5 parts by weight, preferably 0.03 to 0.3 parts by weight, based on 1 part by weight of conductive fine particles as a solid content.
[0058]
The solid content concentration in the coating liquid for forming a transparent conductive film according to the present invention (total amount of indium-based oxide fine particles and additives such as fine metal particles, fine particle carbon, dye, and pigment added as needed) is liquid. From the viewpoints of the fluidity and dispersibility of particulate components such as indium oxide particles in the coating solution, it is preferably 15% by weight or less, preferably 0.15 to 5% by weight.
[0059]
If the coating liquid for forming the transparent conductive film as described above is used, the indium oxide fine particles are uniformly dispersed, and the obtained transparent conductive film is densely filled with the indium oxide fine particles. Excellent adhesion, and generally 10²-10^FourSince a transparent conductive fine particle layer having a low surface resistance of Ω / □ can be formed, charging can be prevented, and an electromagnetic field generated along with the emission of electromagnetic waves and electromagnetic waves can be effectively shielded.
[0060]
Moreover, since the conductive fine particles are mainly composed of indium oxide-based fine particles, the substrate with a transparent conductive film obtained is excellent in salt water resistance, oxidation resistance and transparency.
Base material with transparent conductive film
Next, the substrate with a transparent conductive film according to the present invention will be specifically described.
A substrate with a transparent conductive film according to the present invention is provided on a substrate, a transparent conductive fine particle layer containing the indium-based oxide fine particles on the substrate, and the transparent conductive fine particle layer. And a transparent film having a lower refractive index than the conductive fine particle layer.
[0061]
The substrate is not particularly limited as long as it is highly transparent, but for example, a film, sheet, or other molded body made of glass, plastic, ceramic or the like is preferably used.
A transparent conductive fine particle layer made of indium oxide fine particles as the conductive fine particles is formed on the substrate.
[0062]
The particle diameter of the indium-based oxide fine particles is 2 to 200 nm, preferably 5 to 150 nm.
[Transparent conductive fine particle layer (sometimes referred to as transparent conductive film if a matrix is included)]
The thickness of the transparent conductive fine particle layer is preferably in the range of 5 to 200 nm, and preferably in the range of 10 to 150 nm. With a thickness in this range, a transparent conductive film with excellent antistatic properties and electromagnetic shielding properties is provided. A substrate can be obtained.
[0063]
Such a transparent conductive film may contain metal fine particles, a colorant, a matrix component, an organic stabilizer, and the like as required, as in the coating solution described above. The same thing is mentioned.
Such a transparent conductive fine particle layer is formed by applying the above-mentioned coating liquid for forming a transparent conductive film on a substrate and drying it.
[0064]
As a method for forming the transparent conductive fine particle layer, for example, a coating solution for forming a transparent conductive film was applied on a substrate by a method such as a dipping method, a spinner method, a spray method, a roll coater method, or a flexographic printing method. Then, it dries at a temperature in the range of room temperature to about 90 ° C.
When the matrix-forming component as described above is contained in the coating liquid for forming a transparent conductive film, the matrix-forming component may be cured.
[0065]
For example, a film formed by applying a coating solution for forming a transparent conductive film is heated at 150 ° C. or higher at the time of drying or after drying, or an uncured film is irradiated with ultraviolet rays or electron beams having a wavelength shorter than that of visible light. X-rays, γ-rays or other electromagnetic waves may be irradiated or exposed to an active gas atmosphere such as ammonia. If it does in this way, hardening of a film formation ingredient will be accelerated and the hardness of the film obtained will become high.
[Transparent coating]
In the substrate with a transparent conductive film according to the present invention, a transparent film having a refractive index lower than that of the transparent conductive fine particle layer is formed on the transparent conductive fine particle layer.
[0066]
The film thickness of the transparent coating at this time is preferably in the range of 50 to 300 nm, preferably 80 to 200 nm.
When the film thickness of the transparent coating is less than 50 nm, the strength and antireflection performance of the film may be inferior.
When the film thickness of the transparent coating exceeds 300 nm, cracks may occur in the film or the strength of the film may decrease, and the film may be too thick and the antireflection performance may be insufficient.
[0067]
Such a transparent film is formed from, for example, inorganic oxides such as silica, titania and zirconia, and composite oxides thereof. In the present invention, a silica-based film made of a hydrolyzable polycondensate of a hydrolyzable organosilicon compound or a silicate polycondensate obtained by dealkalizing an alkali metal silicate aqueous solution is particularly preferable as the transparent film. The base material with a transparent conductive film on which such a transparent film is formed is excellent in antireflection performance.
[0068]
The transparent coating further has an average particle diameter in the range of 5 to 300 nm, preferably 10 to 200 nm, and a refractive index in the range of 1.28 to 1.42, preferably in the range of 1.28 to 1.40. It is desirable to include low refractive index particles.
The average particle diameter of the low refractive index particles used is appropriately selected according to the thickness of the formed transparent film.
[0069]
When the refractive index of the low refractive index particles is 1.42 or less, the obtained substrate with a transparent conductive film has low bottom reflectance and luminous reflectance, and can exhibit excellent antireflection performance.
The content of the low refractive index particles in the transparent coating is 10 to 90% by weight, preferably 20 to 80% by weight in terms of oxide.
[0070]
The low refractive index particles used in the present invention are not particularly limited as long as the average particle diameter and refractive index are in the above ranges, and conventionally known particles can be used. For example, the composite oxide sol disclosed in JP-A-7-133105 filed by the applicant of the present application and the porous composite oxide particles having the coating layer disclosed in WO00 / 37359 can be suitably used.
[0071]
Furthermore, the transparent film may contain additives such as fine particles, dyes, and pigments made of a low refractive index material such as magnesium fluoride, if necessary.
The method for forming the transparent film is not particularly limited, and depending on the material of the transparent film, a dry thin film forming method such as a vacuum evaporation method, a sputtering method, or an ion plating method, or the dipping method or spinner method as described above. A wet thin film forming method such as a spray method, a roll coater method, or a flexographic printing method can be employed.
[0072]
When the transparent film is formed by a wet thin film forming method, a conventionally known coating liquid for forming a transparent film can be used. As such a coating liquid for forming a transparent film, specifically, a coating liquid containing an inorganic oxide such as silica, titania, zirconia, or a composite oxide thereof as a transparent film forming component is used.
In the present invention, a silica-based transparent film-forming coating containing a hydrolyzable polycondensate of a hydrolyzable organosilicon compound or a silicic acid solution obtained by dealkalizing an alkali metal silicate aqueous solution as a coating film for forming a transparent film A liquid is preferable, and it is particularly preferable to contain a hydrolyzed polycondensate of alkoxysilane represented by the following general formula [1]. The silica-based coating formed from such a coating solution has a refractive index smaller than that of the conductive fine particle layer containing indium oxide fine particles, and the obtained substrate with a transparent conductive coating is excellent in antireflection properties.
[0073]
R_aSi (OR ')_4-a            [1]
(In the formula, R is a vinyl group, an aryl group, an acrylic group, an alkyl group having 1 to 8 carbon atoms, a hydrogen atom or a halogen atom, and R ′ is a vinyl group, an aryl group, an acrylic group, or a carbon system having 1 to 8 carbon atoms. Alkyl group, -C₂H_FourOC_nH_{2n + 1}(N = 1 to 4) or a hydrogen atom, and a is an integer of 1 to 3. )
Such alkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctylsilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, methyltriisopropoxysilane, Examples include vinyltrimethoxysilane, phenyltrimethoxysilane, and dimethyldimethoxysilane.
[0074]
When one or more of the above alkoxysilanes are hydrolyzed in the presence of an acid catalyst, for example, in a water-alcohol mixed solvent, a coating solution for forming a transparent film containing a hydrolyzed polycondensate of alkoxysilane is obtained. . It is preferable that the density | concentration of the film formation component contained in such a coating liquid is 0.5 to 2.0 weight% in conversion of an oxide.
The coating liquid for forming a transparent film used in the present invention has an average particle diameter in the range of 5 to 300 nm, preferably 10 to 200 nm, and a refractive index of 1.28 to 1.42, more preferably 1.28 to 1. It is desirable to include low refractive index particles in the range of .40.
[0075]
In the present invention, a film formed by applying such a coating solution for forming a transparent film is heated at 150 ° C. or higher at the time of drying or after drying, or ultraviolet light having a wavelength shorter than that of visible light is applied to an uncured film. Further, electromagnetic waves such as electron beams, X-rays and γ-rays may be irradiated or exposed to an active gas atmosphere such as ammonia. If it does in this way, hardening of a film formation ingredient will be accelerated and the hardness of the transparent film obtained will become high.
[0076]
Further, when the transparent coating film forming coating solution is applied to form a coating film, the transparent coating film forming coating solution is applied while maintaining the transparent conductive fine particle layer at about 40 to 90 ° C. As a result, ring-shaped irregularities are formed on the surface of the transparent coating, and an anti-glare substrate with a transparent coating with little glare is obtained.
Display device
The substrate with a transparent conductive film according to the present invention generally has 10 necessary for antistatic and electromagnetic shielding.²-10^FourIt has a surface resistance in the range of Ω / □, is excellent in transparency and has sufficient antireflection performance in the visible light region and near infrared region, and is suitably used as a front plate of a display device.
[0077]
The display device according to the present invention is a device that electrically displays an image such as a cathode ray tube (CRT), a fluorescent display tube (FIP), a plasma display (PDP), a liquid crystal display (LCD), and the like. A front plate made of a substrate with a transparent conductive film.
When a display device having a conventional front plate is operated, an image is displayed on the front plate, and at the same time, the front plate is charged or electromagnetic waves are emitted from the front plate. The face plate is approximately 10 as described above.²-10^FourSince it is composed of a substrate with a transparent conductive film having a surface resistance of Ω / □, it is possible to prevent such charging or effectively shield electromagnetic waves and electromagnetic fields generated by the emission of these electromagnetic waves. it can.
[0078]
In addition, when reflected light is generated on the front plate of the display device, the display image is difficult to see due to the reflected light. In the display device according to the present invention, the front plate has sufficient antireflection performance in the visible light region and the near infrared region. Since it is comprised with the base material with a transparent conductive film which has this, such reflected light can be prevented effectively.
Furthermore, the front plate of the cathode ray tube is composed of a substrate with a transparent conductive film according to the present invention, and among these transparent conductive films, a small amount is added to at least one of the transparent conductive fine particle layer and the transparent film formed thereon. When these dyes or pigments are contained, each of these dyes or pigments absorbs light having a specific wavelength, thereby improving the contrast of a display image broadcast from the cathode ray tube.
[0079]
【The invention's effect】
According to the present invention, indium-based oxidation in which indium-based oxide fine particles having a uniform particle diameter are stably monodispersed without firing at a high temperature and without pulverization in the presence of acid or alkali after firing. A fine particle-dispersed sol and a production method thereof are provided.
[0080]
Furthermore, by using the indium oxide fine particles as conductive fine particles, a uniform and dense film can be obtained, which is suitable for the production of a substrate with a transparent conductive film excellent in conductivity, film strength and the like. A coating liquid for forming a transparent conductive film that can be used, and a substrate with a transparent conductive film formed using the coating liquid are provided.
Furthermore, if such a substrate with a transparent conductive film is used as a front plate of a display device, it is excellent in antistatic performance, electromagnetic shielding performance, antireflection performance, etc., and also in salt water resistance and oxidation resistance. Therefore, a display device having excellent durability can be provided.
[0081]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
[0082]
[Example 1]
Indium oxide fine particles ( ITO-1 ) Preparation of dispersion sol
Step (a)
A solution obtained by dissolving 79.9 g of indium nitrate in 686 g of water and a solution obtained by dissolving 12.7 g of potassium stannate in a potassium hydroxide solution having a concentration of 10% by weight were prepared. Was added to 1000 g of pure water maintained at 50 ° C. over 2 hours. During this time, the pH in the system was maintained at 11, and indium hydroxide containing tin was prepared.
[0083]
Next, indium hydroxide containing tin was separated by filtration, washed sufficiently with warm water, and then indium hydroxide containing tin was dispersed in water so that the concentration as oxide was 4% by weight. A dispersion was prepared. First, alkali metal was removed using a cation exchange resin, and then anions were removed using an anion exchange resin.
Next, an ultrafiltration device (manufactured by Asahi Kasei Kogyo Co., Ltd .: Microza SIP-1013) was added while adding ethyl alcohol to a dispersion of indium hydroxide containing tin having a concentration of 5% by weight as the oxide after washing. The solvent substitution was carried out to prepare an ethyl alcohol dispersion of indium hydroxide containing tin. The concentration of indium hydroxide containing tin in the dispersion as an oxide was 5% by weight, and the water content was 3% by weight.
Step (b)
Subsequently, the ethyl alcohol dispersion of indium hydroxide containing tin was heat-treated at 200 ° C. for 2 hours in an autoclave.
Step (d)
Subsequently, ion removal (desalting) was performed using a cation exchange resin and then an anion exchange resin to prepare a tin-containing indium oxide fine particle (ITO-1) dispersion sol (concentration as an oxide of 5% by weight). .
[0084]
About the obtained tin containing indium oxide fine particle (ITO-1) dispersion | distribution sol, electrical conductivity was measured with the conductivity meter (TOA Electronics company make: CM-14P), and stability of sol was evaluated. The conductivity was measured by diluting the obtained sol so that the concentration as an oxide was 0.5% by weight.
The results are shown in Table 1.
[0085]
Sol stability
A sol having a concentration of 5% by weight as an oxide was placed in a transparent sample bottle and allowed to stand at 25 ° C. for 24 hours, and then visually observed and evaluated according to the following criteria.
Has the same transparency as the initial stage: ○
Two-phase separation of transparent and translucent phases is observed: △
Sediment is observed at the bottom of the sample bottle: ×
In addition, X-ray diffraction patterns were measured for indium oxide fine particles (ITO-1) obtained by drying at 110 ° C. for 2 hours, and the peak in the plane index (2, 2, 2) attributed to indium oxide. (P_A) And the peak in the plane index (2, 2, 0) attributed to indium hydroxide (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) And its ratio (HP_B2) / (HP_A) The X diffraction pattern is shown in FIG.
[0086]
Further, a TEM photograph was taken, the particle diameter was measured for 20 particles, and this average value was shown as the average particle diameter in Table 1.
[0087]
[Example 2]
Indium oxide fine particles ( ITO-2 ) Preparation of dispersion sol
Step (c)
After step (b) carried out in the same manner as in Example 1, solvent substitution was performed using an ultrafiltration device while adding ethyl alcohol to the resulting dispersion, and dispersion of indium oxide fine particles containing tin in ethyl alcohol was performed. A liquid was prepared. At this time, the concentration as an oxide was 5% by weight, and the water content was 0.5% by weight.
[0088]
Subsequently, the ethyl alcohol dispersion of indium hydroxide containing tin was again heat-treated at 200 ° C. for 2 hours in an autoclave.
Step (d)
Subsequently, ion removal (desalting) was performed in the same manner as in Example 1 to prepare an indium-based oxide fine particle (ITO-2) dispersion sol (concentration as an oxide of 5% by weight).
[0089]
The resulting indium oxide fine particle (ITO-2) dispersed sol was evaluated for electrical conductivity and sol stability, and the results are shown in the table.
In addition, for indium oxide fine particles (ITO-2), an X-ray diffraction pattern was measured, and the peak (P, P) in the plane index (2, 2, 2) attributed to indium oxide_A) And the peak in the plane index (2, 2, 0) attributed to indium hydroxide (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) And its ratio (HP_B2) / (HP_A)
[0090]
The results are shown in Table 1.
Further, a TEM photograph was taken, the particle diameter was measured for 20 particles, and this average value was taken as the average particle diameter. The results are shown in Table 1.
[0091]
[Example 3]
Indium oxide fine particles ( ITO-3 ) Preparation of dispersion sol
Step (a)
To 600 g of an indium hydroxide-containing ethyl alcohol dispersion (concentration 5 wt% as an oxide and water content 3 wt%) obtained in the same manner as in step (a) of Example 1, an indium oxide species was added. As a particle, 150 g of the indium oxide fine particle (ITO-1) dispersion sol (concentration 5% by weight as an oxide) prepared in Example 1 was mixed and MO was mixed._G/ MO_Z= 4.0 A mixed dispersion of an indium hydroxide organic solvent dispersion of 4.0 and an indium oxide seed particle dispersion sol was prepared.
Step (b)
Subsequently, the mixed dispersion was heat-treated at 200 ° C. for 2 hours in an autoclave.
Step (d)
Subsequently, ion removal (desalting) was performed using a cation exchange resin and then an anion exchange resin to prepare an indium oxide fine particle (ITO-3) dispersion sol (solid content concentration 5 wt%).
[0092]
The resulting indium oxide fine particle (ITO-3) dispersed sol was evaluated for electrical conductivity and sol stability, and the results are shown in the table.
In addition, the X-ray diffraction pattern of indium oxide fine particles (ITO-3) obtained by drying at 110 ° C. for 2 hours was measured, and the peak in the plane index (2, 2, 2) attributed to indium oxide (P_A) And the peak in the plane index (2, 2, 0) attributed to indium hydroxide (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) And its ratio (HP_B2) / (HP_A)
[0093]
The results are shown in Table 1. Separately, the X-ray diffraction pattern is shown in FIG.
Further, a TEM photograph was taken, the particle diameter was measured for 20 particles, and this average value was taken as the average particle diameter. The results are shown in Table 1.
[0094]
[Example 4]
Indium oxide fine particles ( ITO-4 ) Preparation of dispersion sol
To 600 g of an indium hydroxide-containing ethyl alcohol dispersion (concentration 5 wt% as oxide and 3 wt% water content) obtained in the same manner as in step (a) of Example 1, an indium oxide species was added. Mixing 100 g of the indium oxide fine particle (ITO-1) dispersion sol (concentration as an oxide of 5% by weight) prepared in Example 1 as MO_G/ MO_Z= Indium oxide fine particles (ITO-4) in the same manner as in Example 3 except that a mixed dispersion of an indium hydroxide organic solvent dispersion of 6.0 and an indium oxide seed particle dispersion sol was prepared. A dispersion sol (concentration as an oxide of 5% by weight) was prepared.
[0095]
The obtained indium oxide fine particle (ITO-4) dispersed sol was measured for electric conductivity, and the stability of the sol was evaluated. The results are shown in Table 1.
In addition, for indium oxide fine particles (ITO-4), an X-ray diffraction pattern was measured, and the peak (P, P) in the plane index (2, 2, 2) attributed to indium oxide_A) And the peak in the plane index (2, 2, 0) attributed to indium hydroxide (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) And its ratio (HP_B2) / (HP_A) The results are shown in Table 1.
[0096]
Further, a TEM photograph was taken, the particle diameter was measured for 20 particles, and this average value was taken as the average particle diameter. The results are shown in Table 1.
[0097]
[Comparative Example 1]
Indium oxide fine particles ( ITO-5 ) Preparation of dispersion sol
A solution obtained by dissolving 79.9 g of indium nitrate in 686 g of water and a solution obtained by dissolving 12.7 g of potassium stannate in a potassium hydroxide solution having a concentration of 10% by weight were prepared. Was added to 1000 g of pure water maintained at 50 ° C. over 2 hours. During this time, the pH in the system was maintained at 11. The tin-containing indium oxide hydrate dispersion was filtered and washed from the obtained tin-containing indium oxide hydrate dispersion, and then dispersed again in water to give a metal oxide precursor having a concentration of 10% by weight as an oxide. A hydroxide dispersion was prepared. This dispersion was spray-dried at a temperature of 100 ° C. to prepare a metal oxide precursor hydroxide powder. The powder was heat-treated at 550 ° C. for 2 hours in a nitrogen gas atmosphere.
[0098]
This was dispersed in ethanol to a concentration of 30% by weight, adjusted to pH 3.5 with an aqueous nitric acid solution, and then ground in a sand mill for 0.2 hours while maintaining the mixture at 30 ° C. Was prepared. Subsequently, ethanol was added to prepare an indium oxide fine particle (ITO-5) dispersion sol having a concentration of 20% by weight as an oxide.
Part of the obtained indium oxide fine particle (ITO-5) dispersion sol was diluted to a concentration of 5% by weight as an oxide, and the stability was evaluated. The electrical conductivity was evaluated by diluting to%, and the results are shown in Table 1.
[0099]
In addition, for indium oxide fine particles (ITO-5), an X-ray diffraction pattern was measured, and the peak (P, P) in the plane index (2, 2, 2) attributed to indium hydroxide_A) And the peak in the plane index (2, 2, 0) attributed to indium hydroxide (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) And its ratio (HP_B2) / (HP_A) The results are shown in Table 1. FIG. 2 shows the X-ray diffraction pattern of the indium oxide fine particles (ITO-5).
[0100]
Further, a TEM photograph was taken, the particle diameter was measured for 20 particles, and the average value was taken as the average particle diameter.
[0101]
[Comparative Example 2]
Indium oxide fine particles ( ITO-6 ) Preparation of dispersion sol
Indium oxide fine particle (ITO-6) dispersion sol (concentration as oxide 5% by weight) was obtained in the same manner as in Example 1 except that the temperature of the autoclave was changed to 100 ° C. in the step (b) of Example 1. Prepared.
[0102]
The obtained indium-based oxide fine particle (ITO-6) dispersed sol was evaluated for electric conductivity and sol stability, and the results are shown in Table 1.
In addition, for indium oxide fine particles (ITO-6), an X-ray diffraction pattern was measured, and the peak (P, P) in the plane index (2, 2, 2) attributed to indium hydroxide._A) And the peak in the plane index (2, 2, 0) attributed to indium hydroxide (P_B2) And peak (P_B2) Peak height (HP_B2) And peak (P_A) Peak height (HP_A) And its ratio (HP_B2) / (HP_A) The results are shown in Table 1. FIG. 3 shows the X-ray diffraction pattern of indium oxide fine particles (ITO-6).
[0103]
Further, a TEM photograph was taken, the particle diameter was measured for 20 particles, and the average value was taken as the average particle diameter.
[Evaluation]
Coating liquid for forming transparent conductive film (C-1) ~ (C-6) Preparation of
First, water and a 2: 1 mixed solvent of butylcellsolve are mixed so that the indium-based oxide fine particles (ITO-1) to (ITO-6) dispersed sol obtained above have the concentrations shown in Table 1. Then, coating liquids (C-1) to (C-6) for forming a transparent conductive film were prepared.
[0104]
Stability was evaluated about each obtained coating liquid for transparent conductive film formation, and the result was shown in the table | surface.
Coating solution stability
The coating solution was put in a transparent sample bottle and allowed to stand in a thermostatic bath at 50 ° C. for 24 hours, and this was examined by visual observation and change in viscosity by shaking, and evaluated according to the following criteria.
[0105]
Has the same transparency as the initial stage and has no change in viscosity: ○
Increase in viscosity is observed: △
Precipitates are observed at the bottom of the sample bottle, and the viscosity increases: ×
Coating liquid for transparent film formation (T) Preparation of
Normal ethyl silicate (SiO₂: 28 wt%) 50 g of ethanol, 194.6 g of ethanol, 1.4 g of concentrated nitric acid, and 34 g of pure water were stirred at room temperature for 5 hours, and SiO 2₂A liquid (M) containing a matrix-forming component having a concentration of 5% by weight was prepared. To this was added a mixed solvent of ethanol / butanol / diacetone alcohol / isopropanol (2: 1: 1: 5 weight mixing ratio), and SiO 2₂A coating solution (T) for forming a transparent film having a concentration of 1% by weight was prepared.
[0106]
Panel glass with transparent conductive coating ( P-1 ) ~ ( P-6) Manufacturing of
While maintaining the surface of the CRT panel glass (17 ") at 40 ° C, the above-mentioned coating liquids (C-1) to (C-6) for forming the transparent conductive film were respectively formed by spinner method at 100 rpm for 90 seconds The film thickness of the conductive layer at this time was measured, and the results are shown in the table.
[0107]
Next, on the transparent conductive fine particle layer thus formed, the coating liquid for forming a transparent film (T) was similarly applied and dried at 100 rpm for 90 seconds by a spinner method, and 30 ° C. at 30 ° C. The substrate was baked for minutes to obtain a substrate with a transparent conductive film. The film thickness of the transparent coating at this time was formed to be 50 nm.
The surface resistance of these transparent conductive film-coated substrates was measured with a surface resistance meter (Mitsubishi Yuka Co., Ltd .: LORESTA), and haze was measured with a haze computer (Nippon Denshoku Co., Ltd .: 3000A). The reflectance is measured using a reflectance meter (manufactured by Otsuka Electronics Co., Ltd .: MCPD-2000). The reflectance at the wavelength having the lowest reflectance in the wavelength range of 400 to 700 nm is defined as the bottom reflectance. The average reflectance at 700 nm was determined as the luminous reflectance.
[0108]
The results are shown in Table 1.
[0109]
[Table 1]

[Brief description of the drawings]
1 shows an X-ray diffraction pattern of indium oxide fine particles according to the present invention produced in Example 1. FIG.
2 shows an X-ray diffraction pattern of conventional indium oxide fine particles produced in Comparative Example 1. FIG.
3 shows an X-ray diffraction pattern of conventional indium oxide fine particles produced in Comparative Example 2. FIG.

Claims (8)

In the X-ray diffraction pattern, at least the peak (P _A ) in the plane index (2, 2, 2) attributed to indium oxide and the peak in the plane index (2, 0, 0) attributed to indium hydroxide ( P _B1 ), having a peak (P _B2 ) in the plane index ( _{2, 2, 0} ), and the peak height (HP _B2 ) of the peak (P _B2 ) and the peak height (HP _A ) of the peak (P _A ) The ratio (HP _B2 ) / (HP _A ) is ½ or less,
Indium oxide, indium-based oxide particles S n or F is characterized by comprising indium oxide doped.   Electrical conductivity of a sol in which the indium oxide fine particles according to claim 1 are dispersed in a dispersion medium in which the ratio of water in the dispersion medium is 80% by weight or more so that the concentration as an oxide is 4% by weight. The indium-based oxide fine particles according to claim 1, wherein the degree is 100 μS / cm or less. The method for producing indium oxide fine particles according to claim 1 or 2, comprising the following steps:
(A) preparing an organic solvent dispersion of indium hydroxide or indium hydroxide containing indium hydroxide containing tin or fluorine ;
(B) The process of heat-processing the said organic-solvent dispersion liquid in a pressure-resistant container in the temperature range of 120-400 degreeC. The method for producing indium oxide fine particles according to claim 1 or 2, comprising the following steps:
(A ') organic indium hydroxide or tin or indium-based hydroxide and indium oxide containing indium hydroxide containing fluorine, S n or F is indium-based oxide species particles comprising indium oxide doped, Preparing a solvent mixture dispersion;
(B) The process of heat-processing the obtained organic-solvent dispersion liquid in a pressure-resistant container in the temperature range of 120-400 degreeC.   5. The heat treatment is carried out by dehydration or replacement with another organic solvent as necessary, and further heat treatment at a temperature range of 120 to 400 ° C. and / or deionization treatment. A method for producing indium-based oxide fine particles as described in 1.   A coating solution for forming a transparent conductive film, comprising the indium oxide fine particles according to claim 1 or 2 and a polar solvent. A substrate;
A transparent conductive fine particle layer comprising the indium-based oxide fine particles according to claim 1 or 2 on a substrate;
A substrate with a transparent conductive film, comprising: a transparent film provided on the transparent conductive fine particle layer and having a refractive index lower than that of the transparent conductive fine particle layer.   A display device comprising a front plate comprising the substrate with a transparent conductive film according to claim 7, wherein the transparent conductive film is formed on an outer surface of the front plate.

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