JP2021084825A - Mixed composite tungsten oxide fine particle powder, mixed composite tungsten oxide fine particle dispersion liquid, and mixed composite tungsten oxide fine particle dispersion - Google Patents

Abstract

To provide a composite tungsten oxide fine particle powder, a composite tungsten oxide fine particle dispersion liquid, and a composite tungsten oxide fine particle dispersion in which blueness is suppressed to the extent that b* value becomes a positive value while securing excellent infrared absorption characteristics.SOLUTION: A mixed composite tungsten oxide fine particle powder comprises composite tungsten oxide fine particles having a crystallite diameter of 10 nm or more and 35 nm or less and composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less and has a value of a ratio of "(mass of the composite tungsten oxide fine particles having the crystallite diameter of 10 nm or more and 35 nm or less)/(mass of the composite tungsten oxide fine particles having the crystallite diameter of 45 nm or more and 100 nm or less)" in a range of 1 or more and 3 or less.SELECTED DRAWING: Figure 1

Description

The present invention has a mixed composite tungsten oxide fine particle powder, a mixed composite tungsten oxide fine particle dispersion liquid, and a mixed composite having a predetermined color while having good visible light transmission and excellent infrared absorption characteristics. Regarding tungsten oxide fine particle dispersion.

In recent years, the demand for infrared absorbers has increased rapidly, and many patent applications have been filed for infrared absorbers. Looking at these applications from a functional point of view, for example, in the fields of window materials for various buildings and vehicles, while maintaining brightness by blocking light in the infrared region while sufficiently taking in visible light. Some are aimed at suppressing the temperature rise in the room.

The present inventors disclose in Patent Document 1 an infrared shielding material fine particle dispersion in which infrared shielding material fine particles are dispersed in a medium, and excellent optical properties, conductivity, and a manufacturing method of the infrared shielding material fine particle dispersion. did. Above all, the infrared shielding property of the infrared shielding material fine particle dispersion was superior to that of the conventional shielding material.

The above-mentioned infrared shielding material fine particles are fine particles of tungsten oxide represented by the general formula WyOz (where W is tungsten, O is oxygen, 2.2 ≦ z / y ≦ 2.999), and / and the general formula. MxWyOz (However, M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, One or more elements selected from Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1, 2.2 ≦ z / y ≦ 3.0 ), The particle diameter of the infrared shielding material fine particles is 1 nm or more and 800 nm or less.

In Patent Document 2, a laminated glass in which fine particles of composite tungsten oxide and / and fine particles of hexaboroxide are dispersed is a laminated glass filled between glass plates, and has an excellent infrared absorption function. However, a product having a low haze value and excellent visible light transparency has been proposed.

However, the infrared shielding material fine particle dispersion and the laminated glass disclosed in Patent Documents 1 and 2 are all colored slightly blue due to the influence of containing the composite tungsten oxide, and improvement is required from the viewpoint of design. It had been.

Therefore, for example, as in Patent Document 3, by incorporating the above-mentioned composite tungsten oxide and a compound having maximum absorption in the wavelength region of 300 to 500 nm, the bluish tint peculiar to the composite tungsten oxide is suppressed or removed. An infrared shielding filter has been proposed.

JP-A-2010-168430 Japanese Unexamined Patent Publication No. 2010-202495 Japanese Unexamined Patent Publication No. 11-181336 Japanese Unexamined Patent Publication No. 2008-30798

However, according to the study by the present inventors, for example, the near-infrared ray shielding filter that suppresses or removes the bluish color disclosed in Patent Document 3 has insufficient removal of the bluish color.
Here, for example, in the composite tungsten oxide having infrared absorption characteristics disclosed in Patent Document 4, b * in the L * a * b * color system showed a negative value. However, since the compound having maximum absorption in the wavelength region of 300 to 500 nm is an organic material, it has low weather resistance and cannot withstand the usage environment in fields such as window materials of various buildings and vehicles.

On the other hand, in the composite tungsten oxide fine particles, the value of b * changes from negative to positive as the particle size of the fine particles increases. Therefore, the present inventions and others have tried to solve the above-mentioned problems by increasing the particle size of the composite tungsten oxide fine particles. However, as the particle size of the fine particles increases, light scattering in the short wavelength region increases, and the visible light transmittance of the composite tungsten oxide fine particles decreases, making it impossible to ensure excellent infrared absorption characteristics. Was found.

The present invention has been made under the above-mentioned circumstances, and the problem to be solved is to have a bluish tint to the extent that the value of b * becomes a positive value while ensuring excellent infrared absorption characteristics. It is to provide the suppressed composite tungsten oxide fine particle powder, the composite tungsten oxide fine particle dispersion liquid, and the composite tungsten oxide fine particle dispersion.

In order to solve the above-mentioned problems, the present inventors have studied a configuration for removing the bluish tint of the composite tungsten oxide fine particles while ensuring excellent infrared absorption characteristics. As a result, two or more types of composite tungsten oxide fine particles having different crystallite diameters are mixed in a specific range ratio, and two or more types of composite tungsten oxide fine particles having different crystallite diameters are mixed. The present invention has been completed with the idea that the above-mentioned problems can be solved by using fine particle powder, an admixture composite tungsten oxide fine particle dispersion, and an admixture composite tungsten oxide fine particle dispersion.

That is, the first invention for solving the above-mentioned problems is
It contains composite tungsten oxide fine particles having a crystallite diameter of 10 nm or more and 35 nm or less, and composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less.
The value of the ratio of "(mass of composite tungsten oxide fine particles having a crystallite diameter of 10 nm or more and 35 nm or less) / (mass of composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less)" is in the range of 1 or more and 3 or less. It is an admixture composite tungsten oxide fine particle powder.

The admixture composite tungsten oxide fine particle powder, the admixture composite tungsten oxide fine particle dispersion, and the admixture composite tungsten oxide fine particle dispersion according to the present invention have excellent infrared absorption characteristics but have a bluish tint removed. Excellent in sex.

It is a production flow chart of the admixture composite tungsten oxide fine particle powder, the admixture composite tungsten oxide fine particle dispersion liquid, and the admixture composite tungsten oxide fine particle dispersion according to the present invention. It is a schematic plan view of the crystal structure in the composite tungsten oxide having a hexagonal crystal structure.

An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a production flow chart of an admixture composite tungsten oxide fine particle powder, an admixture composite tungsten oxide fine particle dispersion liquid, and an admixture composite tungsten oxide fine particle dispersion according to the present invention.

As shown in FIG. 1, first, the composite tungsten oxide fine particles (A) are prepared. Then, the composite tungsten oxide fine particles (A) are divided (i), and the divided composite tungsten oxide fine particles (A) are subjected to wet pulverization / dispersion treatments (ii) and (iii), respectively, to be predetermined. The composite tungsten oxide fine particle dispersion liquids (B) and (C) having the crystallite diameter of (C) are obtained. The dispersions of the composite tungsten oxide fine particle dispersions (B) and (C) having the predetermined crystallite diameter are mixed (iv) at a predetermined ratio, and the mixed composite tungsten oxide fine particle dispersion according to the present invention ( D). The admixture composite tungsten oxide fine particle dispersion liquid (D) becomes the admixture composite tungsten oxide fine particle dispersion (E) according to the present invention by being dispersed (v) in a predetermined medium. Further, the solvent is removed (vi) from the miscible composite tungsten oxide fine particle dispersion liquid (D) to obtain the miscible composite tungsten oxide fine particle (F) according to the present invention. The mixed composite tungsten oxide fine particle dispersion (E) according to the present invention is also obtained by dispersing (vii) the mixed composite tungsten oxide fine particle (F) in a predetermined medium.

Hereinafter, the present invention is described in [1] composite tungsten oxide fine particles and a method for producing the same, [2] composite tungsten oxide fine particle dispersion having a predetermined crystallite diameter [3] mixed composite tungsten oxide fine particle dispersion, [4]. ] The admixture composite tungsten oxide fine particle dispersion, and [5] the admixture composite tungsten oxide fine particle powder will be described in this order.

[1] Composite tungsten oxide fine particles and a method for producing the same,
In general, it is known that a material containing free electrons exhibits a reflection absorption response to electromagnetic waves around a region of sunlight having a wavelength of 200 nm to 2600 nm due to plasma oscillation. It is known that when the powder of such a substance is made into fine particles smaller than the wavelength of light, geometric scattering in the visible light region (wavelength 380 nm to 780 nm) is reduced and transparency in the visible light region can be obtained.
In the present invention, "transparency" is used to mean "less scattering and high transparency with respect to light in the visible light region."

In general, since there are no effective free electrons in tungsten oxide (WO ₃ ), the absorption and reflection characteristics in the infrared region are small, and it is not effective as infrared absorption fine particles.
On the other hand, WO ₃ having an oxygen deficiency and composite tungsten oxide obtained by adding a positive element such as Na to WO _{3 are known to be conductive materials and materials having free electrons.} Analysis of single crystals and the like of materials having these free electrons suggests the response of free electrons to light in the infrared region.
Hereinafter, regarding the composite tungsten oxide fine particles (A) according to the present invention and the method for producing the same, (1) the composition of the composite tungsten oxide, (2) the crystal structure of the composite tungsten oxide fine particles, and (3) the composite tungsten oxide. The optical characteristics of the fine particles and (4) the method for producing the composite tungsten oxide fine particles will be described in this order.

(1) Composition of Composite Tungsten Oxide The present inventors have found that there is a particularly effective range as infrared absorbing fine particles in a specific portion of the composition range of the tungsten and oxygen, and it is transparent in the visible light region. In the infrared region, we came up with composite tungsten oxide fine particles that have absorption.

Further, by adding the element M described later to the above-mentioned WO _{3 to form a composite tungsten oxide, free electrons are generated in the WO 3} , and a strong absorption property derived from free electrons is exhibited especially in the near infrared region. , Effective as infrared absorbing fine particles near 1000 nm.

That is, by using the control of the amount of oxygen and the addition of the element M that generates free electrons in combination with _{respect to the WO 3, more efficient infrared absorbing fine particles can be obtained.} When the general formula of the infrared absorbing fine particles in which the control of the amount of oxygen and the addition of the element M that generates free electrons are used is described as MxWyOz (where M is the M element, W is tungsten, and O is oxygen). , 0.001 ≦ x / y ≦ 1, 2.0 ≦ z / y ≦ 3, and infrared absorbing fine particles satisfying the relationship are desirable.

First, the value of x / y indicating the amount of the element M added will be described.
If the value of x / y is larger than 0.001, a sufficient amount of free electrons are generated in the composite tungsten oxide, and the desired infrared absorption effect can be obtained. Then, as the amount of the element M added increases, the amount of free electrons supplied increases and the infrared absorption efficiency also increases, but the effect is saturated when the value of x / y is about 1. Further, when the value of x / y is smaller than 1, it is preferable because it is possible to avoid the formation of an impurity phase in the infrared absorbing fine particles.

The element M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au. , Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be , Hf, Os, Bi, I, and preferably one or more.

Here, from the viewpoint of stability in the MxWyOz to which the element M is added, the element M is an alkali metal, an alkaline earth metal, a rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir. , Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti , Nb, V, Mo, Ta, Re, more preferably one or more elements selected from. From the viewpoint of improving the optical properties and weather resistance of the infrared absorbing fine particles, it is more preferable that the element M belongs to an alkaline earth metal element, a transition metal element, a group 4B element, and a group 5B element.

Regarding the value of z / y indicating the control of the amount of oxygen, in 2.0 ≦ z / y ≦ 3.0, there is a supply of free electrons depending on the amount of the element M added as described above. Therefore, 2.0 ≦ z / y ≦ 3.0 is preferable, 2.2 ≦ z / y ≦ 3.0 is more preferable, and 2.45 ≦ z / y ≦ 3.0 is more preferable.

(2) Crystal Structure of Composite Tungsten Oxide Fine Particles When the composite tungsten oxide fine particles (A) according to the present invention have a hexagonal crystal structure, the transmission of the fine particles in the visible light region is improved and absorption in the infrared region is improved. Is improved. The crystal structure of this hexagonal crystal will be described with reference to FIG. 2, which is a schematic plan view.

In FIG. 2, _six octahedrons formed by WO 6 units indicated by reference numeral 11 are assembled to form a hexagonal void, and the element M indicated by reference numeral 12 is arranged in the void to form one. Units are formed, and a large number of these one unit are assembled to form a hexagonal crystal structure.
Then, in order to obtain the effect of improving the transmission of light in the visible light region and improving the absorption of light in the infrared region, the composite tungsten oxide fine particles include the unit structure described with reference to FIG. The composite tungsten oxide fine particles (A) may be crystalline or amorphous.

When the cation of the element M is added to the hexagonal voids and exists, the transmission of light in the visible light region is improved and the absorption of light in the infrared region is improved. Here, in general, the hexagonal crystal is likely to be formed when the element M having a large ionic radius is added. Specifically, hexagonal crystals are likely to be formed when Cs, K, Rb, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn are added. Of course, elements other than these are not limited to the above-mentioned elements as long as the above-mentioned element M exists in the hexagonal voids formed in _{WO 6 units.}

When the composite tungsten oxide fine particles (A) having a hexagonal crystal structure have a uniform crystal structure, the amount of the additive element M added is preferably 0.2 or more and 0.5 or less in terms of x / y, and further. It is preferably 0.33. When the value of x / y is 0.33, it is considered that the above-mentioned element M is arranged in all the hexagonal voids.

In addition to hexagonal crystals, tetragonal and cubic composite tungsten oxides are also effective as infrared absorbing fine particles. The absorption position in the infrared region tends to change depending on the crystal structure, and the absorption position tends to move to the longer wavelength side in the order of cubic <tetragonal <hexagonal. Along with this, the absorption in the visible light region is less in the order of hexagonal crystal, tetragonal crystal, and cubic crystal. Therefore, it is preferable to use a hexagonal composite tungsten oxide for applications in which light in a more visible light region is transmitted and light in a more infrared region is absorbed. However, the tendency of the optical characteristics described here is only a rough tendency and changes depending on the type of added element, the amount of added element, and the amount of oxygen, and the present invention is not limited to this.

(3) Optical Characteristics of Composite Tungsten Oxide Fine Particles The composite tungsten oxide fine particles (A) according to the present invention absorb a large amount of light in the near infrared region, particularly in the vicinity of a wavelength of 1000 nm, so that the transmitted color tone is bluish. There are many.

(4) Method for Producing Composite Tungsten Oxide Fine Particles The composite tungsten oxide fine particles (A) according to the present invention are obtained by heat-treating a starting material, which is a tungsten compound, in a reducing gas atmosphere to obtain composite tungsten oxide fine particles. It can be obtained by setting the crystallite diameter of the fine particles to the above-mentioned predetermined value.
Hereinafter, the composite tungsten oxide (A) according to the present invention will be described in the order of (i) starting material and (ii) heat treatment.

(I) Starting Material The starting material for the composite tungsten oxide according to the present invention is a simple substance or a mixture containing a compound of tungsten and element M, respectively. As the raw material for tungsten, tungstic acid powder, tungsten trioxide powder, tungsten dioxide powder, tungsten oxide hydrate powder, tungsten hexachloride powder, ammonium tungstate powder, or tungsten hexachloride powder is dissolved in alcohol and then dried. Tungsten oxide hydrate powder obtained in the above, or tungsten oxide hydrate powder obtained by dissolving tungsten hexachloride in alcohol, adding water to precipitate, and drying this. , Any one or more selected from tungsten compound powder and metallic tungsten powder obtained by drying an aqueous solution of ammonium tungstate is preferable. Examples of the raw material of the element M include element M alone, element M chloride salt, nitrate, sulfate, oxalate, oxide, carbonate, tungstate, hydroxide and the like, but are limited thereto. Not done.

When the above-mentioned starting material is weighed and the composite tungsten oxide according to the present invention is labeled as MxWyOz (where M is the M element, W is tungsten, and O is oxygen) using a general formula, 0.001 Mix and mix in a predetermined amount that satisfies <x / y ≦ 1. At this time, it is preferable that the raw materials for tungsten and the element M are mixed as uniformly as possible, preferably at the molecular level. Therefore, it is most preferable that each of the above-mentioned starting materials is mixed in the form of a raw material solution. Therefore, it is preferable that each starting material is soluble in a solvent such as water or an organic solvent.

If each starting material is soluble in a solvent such as water or an organic solvent, the tungsten according to the present invention is obtained by sufficiently mixing each starting material and the solvent, mixing them, and further volatilizing the solvent. A mixture of starting materials for the compounds can be produced.
However, when a soluble solvent cannot be prepared for each starting material, a mixture of starting materials of the tungsten compound can also be produced by sufficiently and uniformly mixing each starting material by a known means such as a ball mill. ..

(Ii) Heat treatment Next, heat treatment in a reducing gas atmosphere will be described. The starting material is preferably heat-treated at 300 ° C. or higher and 900 ° C. or lower, more preferably 500 to 800 ° C. or lower, and even more preferably 500 to 600 ° C. or lower. If the temperature is 300 ° C or higher, the reaction for producing the composite tungsten oxide having a hexagonal structure according to the present invention proceeds, and if the temperature is 900 ° C or lower, the composite tungsten oxide fine particles or metallic tungsten having a structure other than hexagonal are not intended. It is preferable that a side reaction product is hard to be formed.

The reducing gas at this time is not particularly limited, but H ₂ is preferable. Then, when _{H 2} is used as the reducing gas, the composition of the reducing atmosphere, for example, Ar, is a mixture from 0.1 to 0.8% by volume of _{H 2} in an inert gas such as _{N 2} It is preferably, more preferably 0.1 to 0.5% mixed. When H ₂ is 0.1% to 0.8% by volume, reduction can be efficiently promoted while controlling the generation of oxygen vacancies. Conditions such as the reduction temperature and reduction time, and the type and concentration of the reducing gas can be appropriately selected according to the amount of the sample.
If necessary, the reduction treatment may be carried out in a reducing gas atmosphere, and then the heat treatment may be carried out in an inert gas atmosphere. In this case, the heat treatment in the atmosphere of the inert gas is preferably performed at a temperature of 400 ° C. or higher and 1200 ° C. or lower.

[2] Composite tungsten oxide fine particle dispersion liquid having a predetermined crystallite diameter A composite tungsten oxide fine particle dispersion liquid is produced by dispersing the composite tungsten oxide fine particles (A), that is, infrared absorbing fine particles in a liquid solvent. However, in the present invention, it has a composite tungsten oxide fine particle dispersion liquid (B) having a predetermined crystallite diameter (10 nm or more and 35 nm or less) and a predetermined crystallite diameter (45 nm or more and 100 nm or less). Two types of composite tungsten oxide fine particle dispersion liquid (C) are produced.
In the present invention, the composite tungsten oxide fine particle dispersion liquid (B) having a predetermined crystallite diameter is referred to as "dispersion liquid (B)" and the composite tungsten oxide fine particle dispersion liquid (C) having a predetermined crystallite diameter. May be described as "dispersion liquid (C)".

For both the dispersion liquid (B) and the dispersion liquid (C) having the two types of predetermined crystallite diameters, the composite tungsten oxide fine particles (A) and, if desired, an appropriate amount of a dispersant, a coupling agent, a surfactant and the like are added. It can be obtained by adding to a liquid solvent and performing wet pulverization / dispersion treatment under different conditions.

Hereinafter, with respect to the composite tungsten oxide fine particle dispersion having the two types of predetermined crystallite diameters, (1) solvent, (2) dispersant, (3) crystallite diameter of composite tungsten oxide fine particles, and (4) composite. The dispersion particle size of the tungsten oxide fine particles and (5) wet pulverization / dispersion treatment will be described in this order. The solvent and dispersant are common to the dispersion liquid (B) and the dispersion liquid (C). Then, it is convenient from the viewpoint of the manufacturing process that the contents of the composite tungsten oxide fine particles are the same in the dispersion liquid (B) and the dispersion liquid (C).

(1) Solvent The solvent of the composite tungsten oxide fine particle dispersion liquid has a function of maintaining the dispersibility of the composite tungsten oxide fine particle dispersion liquid and does not cause coating defects when the composite tungsten oxide fine particle dispersion liquid is applied. Function is required.

As the solvent, water, an organic solvent, a vegetable oil, a compound derived from a vegetable oil, a petroleum solvent, an oil or fat, a liquid resin, a liquid plastic for plastics, or a mixture thereof can be selected to produce a composite tungsten oxide fine particle dispersion. .. As the organic solvent satisfying the above requirements, various solvents such as alcohol-based, ketone-based, hydrocarbon-based, glycol-based, and aqueous-based solvents can be selected. Specifically, alcohol solvents such as methanol, ethanol, 1-propanol, isopropanol, butanol, pentanol, benzyl alcohol and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone. Solvents: Ester solvents such as 3-methyl-methoxy-propionate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, propylene Glycol derivatives such as glycol ethyl ether acetate; amides such as formamide, N-methylformamide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone; aromatic hydrocarbons such as toluene and xylene; ethylene chloride, Examples thereof include halogenated hydrocarbons such as chlorbenzene. Among these, organic solvents having low polarity are preferable, and isopropyl alcohol, ethanol, 1-methoxy-2-propanol, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, n-butyl acetate and the like are more preferable. preferable. These solvents can be used alone or in combination of two or more.

As the vegetable oil, flaxseed oil, sunflower oil, tung oil, sesame oil, cottonseed oil, rapeseed oil, soybean oil, rice bran oil, olive oil, palm oil, palm oil, dehydrated sunflower oil and the like are preferable.

As the compound derived from vegetable oil, fatty acid monoester obtained by directly transesterifying a fatty acid of vegetable oil with monoalcohol, vegetable oil such as ethers, and the like are preferable.

As the petroleum-based solvent, Isopar E, Exor Hexane, Exor Heptane, Exor E, Exor D30, Exor D40, Exor D60, Exor D80, Exor D95, Exor D110, Exor D130 (all manufactured by Exor Mobile Co., Ltd.) and the like are preferable.

As the liquid resin, methyl methacrylate and the like are preferable. Examples of the liquid plasticizer for plastics include a plasticizer which is a compound of a monohydric alcohol and an organic acid ester, an ester-based plasticizer such as a polyhydric alcohol organic acid ester compound, and phosphorus such as an organic phosphoric acid-based plasticizer. A preferable example is an acid-based plasticizer. Of these, triethylene glycol di-2-ethylhexaonete, triethylene glycol di-2-ethylbutyrate, and tetraethylene glycol di-2-ethylhexaonate are more preferable because they have low hydrolyzability.

(2) Dispersant The dispersant, coupling agent, and surfactant can be selected according to the intended use, but it is preferable to have an amine-containing group, a hydroxyl group, a carboxyl group, or an epoxy group as a functional group. These functional groups have the effect of adsorbing on the surface of the composite tungsten oxide fine particles, preventing the composite tungsten oxide fine particles from aggregating, and uniformly dispersing the composite tungsten oxide fine particles according to the present invention even in the infrared absorbing film.

Dispersants that can be preferably used include, but are limited to, phosphoric acid ester compounds, polymer-based dispersants, silane-based coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and the like. It's not a thing. Examples of the polymer-based dispersant include acrylic-based polymer dispersants, urethane-based polymer dispersants, acrylic block copolymer-based polymer dispersants, polyether dispersants, polyester-based polymer dispersants, and the like.

The amount of the dispersant added is preferably in the range of 10 parts by mass to 1000 parts by mass, and more preferably in the range of 20 parts by mass to 200 parts by mass with respect to 100 parts by mass of the composite tungsten oxide fine particles. When the amount of the dispersant added is within the above range, the composite tungsten oxide fine particles do not aggregate in the dispersion liquid, and the dispersion stability is maintained.

(3) Crystalline Diameter of Composite Tungsten Oxide Fine Particles The bluish tint of the composite tungsten oxide fine particles according to the present invention is suppressed to the extent that the value of b * becomes a positive value while ensuring excellent infrared absorption characteristics. From the viewpoint of forming fine particles, it is important that the fine particles have a predetermined crystallite diameter.

This is described later in the mixed composite tungsten oxide fine particle dispersion containing the composite tungsten oxide fine particles, the mixed composite tungsten oxide fine particle dispersion, and the mixed composite tungsten oxide fine particle powder according to the present invention, in which the crystallite diameter is 10 nm. In the composite tungsten oxide fine particles of 35 nm or more and the composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less,
The value of the ratio of "(mass of composite tungsten oxide fine particles having a crystallite diameter of 10 nm or more and 35 nm or less) / (mass of composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less)" is in the range of 1 or more and 3 or less. This is because it is important that it is contained in such a way.

In the measurement of the crystallite diameter of the composite tungsten oxide fine particles according to the present invention, the measurement of the X-ray diffraction pattern by the powder X-ray diffraction method (θ-2θ method) and the analysis by the Rietveld method are used. The X-ray diffraction pattern can be measured by using, for example, a powder X-ray diffractometer "X'Pert-PRO / MPD" manufactured by PANalytical Co., Ltd. of Spectris Co., Ltd.

(4) Dispersed particle size of composite tungsten oxide fine particles In order to select the dispersed particle size of the mixed composite tungsten oxide fine particles according to the present invention according to the purpose of use, which will be described later, in the dispersion liquids (B) and (C). The dispersed particle size of the dispersed composite tungsten oxide fine particles can be selected.

First, when used in an application in which transparency is desired to be maintained, it is preferable to have a particle size of 800 nm or less. This is because particles smaller than 800 nm do not completely block light due to scattering, and can maintain visibility in the visible light region and at the same time efficiently maintain transparency. In particular, when the transparency in the visible light region is emphasized, it is preferable to further consider scattering by particles.

When the reduction of scattering by the particles is emphasized, the dispersed particle size is preferably 200 nm or less, preferably 150 nm or less. The reason for this is that if the dispersed particle size of the particles is small, the scattering of light in the visible light region having a wavelength of 400 nm to 780 nm due to geometric scattering or Mie scattering is reduced, and as a result, the infrared absorbing film becomes like frosted glass. It is possible to avoid the loss of clear transparency. That is, when the dispersed particle size is 200 nm or less, the geometrical scattering or Mie scattering is reduced, and a Rayleigh scattering region is formed. This is because in the Rayleigh scattering region, the scattered light is reduced in proportion to the sixth power of the particle size, so that the scattering is reduced and the transparency is improved as the dispersed particle size is reduced.
Further, when the dispersed particle size is 150 nm or less, the scattered light becomes very small, which is preferable. From the viewpoint of avoiding light scattering, it is preferable that the dispersed particle size is small, and if the dispersed particle size is 1 nm or more, industrial production is easy.

By setting the dispersed particle size to 800 nm or less, the haze value of the mixed composite tungsten oxide fine particle dispersion liquid and the mixed composite tungsten oxide fine particle dispersion according to the present invention is 85% or less in visible light transmittance and 30% or less in haze. Can be. If the haze is a value larger than 30%, it becomes like frosted glass and clear transparency cannot be obtained.
The dispersed particle size of the composite tungsten oxide fine particles can be measured by using ELS-8000 or the like manufactured by Otsuka Electronics Co., Ltd. based on the dynamic light scattering method.

(5) Wet pulverization / dispersion treatment By adding the composite tungsten oxide fine particles (A), a dispersant, and if desired, a coupling agent, a surfactant, etc. to a liquid solvent, and performing a wet pulverization / dispersion treatment. , The composite tungsten oxide fine particle dispersion liquid according to the present invention can be obtained.
At this time, the dispersion liquid (B) and the dispersion liquid (C) can be prepared by controlling the conditions of the wet pulverization / dispersion treatment.

The dispersion treatment method can be arbitrarily selected from known methods as long as the composite tungsten oxide fine particles are uniformly dispersed in the solvent, and for example, a method such as a bead mill, a ball mill, a sand mill, or an ultrasonic dispersion can be used. ..
In order to obtain a uniform dispersion liquid (B) and dispersion liquid (C), various additives and dispersants may be added or the pH may be adjusted.

[3] Admixture composite tungsten oxide fine particle dispersion liquid (D)
In the mixed composite tungsten oxide fine particle dispersion liquid (D) according to the present invention, the composite tungsten oxide fine particles having different crystallite diameters are uniform at the nano level by mixing the dispersion liquid (B) and the dispersion liquid (C). Can be obtained by mixing with.
The mixed composite tungsten oxide fine particle dispersion (D) has a crystallite diameter in the range of 10 nm or more and 35 nm or less and a crystallite diameter of 45 nm or more and 100 nm in a histogram in which the vertical axis represents the frequency of existence and the horizontal axis represents the crystallite diameter. It has peaks in the following ranges.
The obtained mixed composite tungsten oxide fine particle dispersion liquid (D) has excellent infrared absorption characteristics and has a bluish tint removed.

The mixing method of the dispersion liquid (B) and the dispersion liquid (C) is not particularly limited, but when mixing a small amount of the dispersion liquid, the dispersion liquids (B) and (C) are put in an appropriate container and stirred. It can be mixed uniformly by shaking the whole container. Further, when a large amount of dispersion liquid is mixed, it can be uniformly mixed by adding the other dispersion liquid while stirring one dispersion liquid using a stirrer or the like. Further, a device capable of uniformly mixing a plurality of liquids inside, such as a liquid mixing type dispenser, can also be used.

As described above, when the content of the composite tungsten oxide fine particles is the same in the dispersion liquid (B) and the dispersion liquid (C), the composite tungsten oxide fine particles having different crystallite diameters are mixed at a predetermined mass ratio. It is convenient because the operation of mixing the dispersion liquid (B) and the dispersion liquid (C) at a predetermined mass ratio can be performed.

Here, the mixing ratio is not particularly limited as long as it is selected so that the influence of one of the dispersion liquid (B) and the dispersion liquid (C) does not become too large. For example, it is possible to preferably select a mixing ratio in which the coloring power (absorbance) of the two types of dispersions is substantially the same. For example, when the concentration ratio of the composite tungsten oxide fine particle dispersion having a crystallite diameter of 25 nm and the composite tungsten oxide fine particle dispersion having a crystallite diameter of 50 nm to have the same visible light transmittance is 1.5 / 1. A mixing ratio of 1.5 / 1 can be preferably selected.

In the case of the composite tungsten oxide fine particle dispersion liquid (B) having a crystallite diameter of 10 nm or more and 35 nm or less and the composite tungsten oxide fine particle dispersion liquid (C) having a crystallite diameter of 45 nm or more and 100 nm or less, "dispersion liquid (B) / dispersion". When the value of the mass ratio of "liquid (C)" is in the range of 1 or more and 3 or less, the influence of one of the dispersion liquids does not become too large. This is because the smaller the crystallite diameter of the composite tungsten oxide fine particles, the lower the coloring power of the dispersion liquid. Therefore, the mixing ratio of the dispersion liquid (B) having a crystallite diameter of 10 nm or more and 35 nm or less with respect to the dispersion liquid (C) having a crystallite diameter of 45 nm or more and 100 nm or less is mixed so as to be an equal amount or more and 3% by mass or less. The composite tungsten oxide fine particle dispersion liquid (D) is prepared.

The content of the composite tungsten oxide fine particles in the mixed composite tungsten oxide fine particle dispersion liquid (D) according to the present invention is preferably 0.01% by mass to 75% by mass. If the content of the composite tungsten oxide fine particles is 0.01% by mass or more, it can be suitably used for manufacturing a coating film or a plastic molded body described later, and if it is 75% by mass or less, industrial production is possible. It's easy. More preferably, it is 1% by mass or more and 35% by mass or less.

[4] Admixture composite tungsten oxide fine particle dispersion (E)
By dispersing the mixed composite tungsten oxide fine particle dispersion liquid (D) according to the present invention or the mixed composite tungsten oxide fine particle powder (F) described later in a solid medium, a dispersed powder, a masterbatch, or infrared absorption can be absorbed. An admixture composite tungsten oxide fine particle dispersion (E) such as a film or an infrared absorbing plastic molded body can be produced.

As an example of a general usage method, a method for producing an infrared absorbing film using the mixed composite tungsten oxide fine particle dispersion liquid (D) according to the present invention will be described. An infrared absorbing film is produced by mixing the above-mentioned mixed composite tungsten oxide fine particle dispersion (D) with a plastic or a monomer to prepare a coating liquid, and forming a coating film on a substrate by a known method. Can be done. The infrared absorbing film is an example of the admixture composite tungsten oxide fine particle dispersion (E) according to the present invention.

As the medium of the coating film, for example, UV curable resin, thermosetting resin, electron beam curable resin, room temperature curable resin, thermoplastic resin and the like can be selected according to the purpose. Specifically, polyethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin, ethylene vinyl acetate copolymer, polyester resin, polyethylene terephthalate resin, fluorine resin, polycarbonate resin, acrylic resin. , Polyvinyl butyral resin can be mentioned. These resins may be used alone or in combination. It is also possible to use a binder using a metal alkoxide. Typical examples of the metal alkoxide are alkoxides such as Si, Ti, Al, and Zr. Binders using these metal alkoxides can form an oxide film by hydrolyzing and polycondensing by heating or the like.

The base material may be a film as described above, but may be a board if desired, and the shape is not limited. As the transparent base material, PET, acrylic, urethane, polycarbonate, polyethylene, ethylene-vinyl acetate copolymer, vinyl chloride, fluororesin and the like can be used according to various purposes. In addition to resin, glass can be used.

[5] Mixed composite tungsten oxide fine particle powder (F)
By removing the solvent (vi) from the miscible composite tungsten oxide fine particle dispersion liquid (D) according to the present invention described above, the miscible composite tungsten oxide fine particle powder (F) according to the present invention can be obtained.

In order to remove the solvent (vi) from the miscible composite tungsten oxide fine particle dispersion (D), it is preferable to dry the mixed composite tungsten oxide fine particle dispersion (D) under reduced pressure. Specifically, the mixed composite tungsten oxide fine particle dispersion liquid (D) may be depressurized while stirring to evaporate the solvent component, thereby separating the mixed composite tungsten oxide fine particle-containing composition and the solvent component. The pressure at the time of depressurization in the drying step is appropriately selected.

By using the vacuum drying method, the efficiency of removing the solvent from the mixed composite tungsten oxide fine particle dispersion (D) is improved, and the mixed composite tungsten oxide fine particle powder according to the present invention is exposed to a high temperature for a long time. Therefore, it is preferable that the mixed composite tungsten oxide fine particles dispersed in the fine particles do not aggregate. Further, the productivity of the mixed composite tungsten oxide fine particles is increased, and the evaporated solvent can be easily recovered, which is preferable from the viewpoint of the environment.

Hereinafter, the present invention will be specifically described with reference to Examples.
However, the present invention is not limited to the following examples.

The crystallite diameter of the composite tungsten oxide fine particles was calculated by analyzing the X-ray diffraction pattern by the Rietveld method. The X-ray diffraction pattern was measured by a powder X-ray diffraction method (θ-2θ method) using a powder X-ray diffractometer (X'Pert-PRO / MPD manufactured by PANalytical Co., Ltd.).
The optical characteristics of the admixture composite tungsten oxide fine particle dispersion (D) and the admixture composite tungsten oxide fine particle dispersion (E) are measured at a wavelength of 200 nm to 2600 nm using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.). It was measured as a transmitted light profile at intervals of 5 nm in the range, and the visible light transmittance and the solar radiation transmittance were calculated according to JIS R3106. The color system of the mixed composite tungsten oxide fine particle dispersion (E) was evaluated using an L * a * b * color system (D65 light source / 10-degree field of view) based on JIS Z 8701.

[Example 1]
_{Hexagonal cesium tungsten bronze (Cs 0.33} WO _z , 2.0 ≤ z ≤ 3.0) powder with Cs / W (molar ratio) = 0.33 (YM-01 manufactured by Sumitomo Metal Mining Co., Ltd.) ) 8% by mass, 24% by mass of the polyacrylate-based dispersant, and 68% by mass of an integer were mixed to obtain a mixed solution. The obtained mixed solution is divided into two (i), and _{together with 0.3 mmφZrO 2} beads, separate paint shakers (paint shaker B and paint shaker C) (both B and C are manufactured by Asada Iron Works Co., Ltd.). ) Was loaded. Wet pulverization / dispersion treatments (ii) and (iii) were performed using the paint shaker B for 13 hours and the paint shaker C for 7 hours, and the dispersion liquid (B) according to Example 1 was subjected to the paint shaker B. Then, the composite tungsten oxide fine particle dispersion liquid (C) according to Example 1 was obtained by the paint shaker C. When the solvent was removed from the obtained dispersions (B) and (C) and the crystallite diameter of the obtained composite tungsten oxide fine particle powder was measured, the crystals of the composite tungsten oxide fine particles derived from the dispersion (B) were measured. The child diameter was 32 nm, and the crystallite diameter of the composite tungsten oxide fine particles derived from the dispersion liquid (C) was 48 nm.

The two types of dispersions (B) and (C) obtained are mixed so that the mass ratio of "(dispersion (B) / dispersion (C)" is 1.2, and shaken well. The mixture was homogenized to obtain a composite tungsten oxide fine particle dispersion liquid (D) according to Example 1.

The mixed composite tungsten oxide fine particle dispersion (D) according to Example 1 is diluted with toluene as a solvent so that the visible light transmittance is 80%, and a glass cell for measurement of a spectrophotometer (GL Science). The transmitted light profile was measured with a model number: S-10-SQ-1, material: synthetic quartz, optical path length: 1 mm) manufactured by Japan Ltd. Prior to the measurement, the baseline of the transmitted light profile was measured with the glass cell filled with toluene, which is the solvent of the dispersion liquid. By measuring the baseline, the light reflection on the surface of the glass cell for the spectrophotometer and the contribution of the light absorption of the solvent can be canceled, and only the light absorption by the mixed composite tungsten oxide fine particles is reflected in the transmitted light profile. It will be. Visible light transmittance, solar radiation transmittance, L *, a *, and b * were calculated from the transmission profile of the obtained mixed composite tungsten oxide fine particle dispersion liquid (D). The evaluation results are shown in Table 2.

Further, the mixed composite tungsten oxide fine particle dispersion liquid (D) according to Example 1 is diluted with toluene as a solvent so that the visible light transmittance is 80%, and the glass cell for measurement of the spectrophotometer ( The transmitted light profile was measured with GL Science Co., Ltd., model number: S-10-SQ-1, material: synthetic quartz, optical path length: 1 mm). Prior to the measurement, the baseline of the transmitted light profile was measured with the glass cell empty. By measuring the baseline, the light reflection on the surface of the glass cell for the spectrophotometer can be canceled, and only the light absorption by the mixed composite tungsten oxide fine particle dispersion is reflected in the transmitted light profile. L *, a *, and b * were calculated from the permeation profile of the obtained mixed composite tungsten oxide fine particle dispersion liquid (D). Then, the value of b * was a positive value. The evaluation results are shown in Table 2.

Next, the solvent was evaporated from the mixed composite tungsten oxide fine particle dispersion liquid (D) according to Example 1 by vacuum flow drying to obtain the mixed composite tungsten oxide fine particle powder (F) according to Example 1. Vacuum flow drying was performed using a vacuum crusher (24P manufactured by Ishikawa Factory Co., Ltd.). The rotation speed was 45 rpm / min, and the heater temperature was set to 70 ° C.

The visible light transmittance of the infrared absorbing sheet, which is the mixed composite tungsten oxide fine particle dispersion (E) obtained later, of the mixed composite tungsten oxide fine particle powder (F) and the polycarbonate resin according to Example 1 is about 80%. (In this example, the composite tungsten oxide fine particles were blended so as to have a concentration of 0.045% by mass). The obtained blend was kneaded at 290 ° C. using a twin-screw extruder and extruded from a T-die to obtain a sheet material having a thickness of 0.75 mm by a calendar roll method to obtain an infrared absorbing sheet according to Example 1. ..

The transmitted light profile of the obtained infrared absorbing sheet according to Example 1 was measured. Visible light transmittance, solar transmittance, L *, a *, and b * were calculated from the obtained transmittance profile. Then, the value of b * was a positive value. The manufacturing conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[Examples 2 and 3]
The same operation as in Example 1 was performed except that the time of the pulverization / dispersion treatment in the wet pulverization / dispersion treatments (ii) and (iii) and the mixed mass ratio of the dispersion liquids (B) and (C) were changed. By doing so, the mixed composite tungsten oxide fine particle dispersion (D), the mixed composite tungsten oxide fine particle dispersion (E), and the mixed composite tungsten oxide fine particle powder (F) according to Examples 2 and 3 are obtained. , The same evaluation as in Example 1 was carried out. Then, in Examples 2 and 3, the value of b * was a positive value in the admixture composite tungsten oxide fine particle dispersion liquid (D) and the admixture composite tungsten oxide fine particle dispersion (E). The manufacturing conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[Comparative Example 1]
_{Hexagonal cesium tungsten bronze (Cs 0.33} WO _z , 2.0 ≤ z ≤ 3.0) powder with Cs / W (molar ratio) = 0.33 (YM-01 manufactured by Sumitomo Metal Mining Co., Ltd.) ) 8% by mass, 24% by mass of the polyacrylate-based dispersant, and 68% by mass of an integer were mixed to obtain a mixed solution. The obtained mixed solution _{was loaded into a paint shaker (manufactured by Asada Iron Works Co., Ltd.) together with 0.3 mmφZrO 2} beads, and pulverized and dispersed for 9 hours to obtain a composite tungsten oxide fine particle dispersion according to Comparative Example 1. It was. After removing the solvent of the obtained dispersion liquid, the crystallite diameter of the composite tungsten oxide fine particles was measured and found to be 38 nm.

By performing the same operation as in Example 1 except that the composite tungsten oxide fine particle dispersion liquid according to Comparative Example 1 was used instead of the mixed composite tungsten oxide fine particle dispersion liquid (D) according to Example 1. , The composite tungsten oxide fine particle dispersion and the composite tungsten oxide fine particle dispersion powder according to Comparative Example 1 were obtained, and the same evaluation as in Example 1 was carried out. Then, in Comparative Example 1, the value of b * was a negative value in the mixed composite tungsten oxide fine particle dispersion liquid (D) and the mixed composite tungsten oxide fine particle dispersion (E). The manufacturing conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[Summary]
As is clear from Table 2, the mixed composite tungsten oxide fine particle dispersion liquid (D) (measured only with the composite tungsten fine particle component) and the mixed composite tungsten oxide fine particle dispersion (E) according to Examples 1 to 3 are , B * were positive values, and the bluish tint was suppressed. Further, it was confirmed that the solar transmittance was clearly lower and the infrared absorption characteristics were excellent as compared with the composite tungsten oxide fine particle dispersion and the composite tungsten oxide fine particle dispersion according to Comparative Example 1. ..

Claims (10)

It contains composite tungsten oxide fine particles having a crystallite diameter of 10 nm or more and 35 nm or less, and composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less.
The value of the ratio of "(mass of composite tungsten oxide fine particles having a crystallite diameter of 10 nm or more and 35 nm or less) / (mass of composite tungsten oxide fine particles having a crystallite diameter of 45 nm or more and 100 nm or less)" is in the range of 1 or more and 3 or less. An admixture composite tungsten oxide fine particle powder characterized by that. In a histogram in which the vertical axis represents the frequency of existence and the horizontal axis represents the crystallite diameter, the histogram is characterized by having peaks in a range of crystallite diameter of 10 nm or more and 35 nm or less and a range of crystallite diameter of 45 nm or more and 100 nm or less. , The mixed composite tungsten oxide fine particle powder according to claim 1. The composite tungsten oxide fine particles are of the general formula MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, One or more elements selected from Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, Yb, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1. , 2.0 ≦ z / y ≦ 3.0). The mixed composite tungsten oxide fine particle powder according to claim 1 or 2. A mixed composite tungsten oxide fine particle dispersion liquid, wherein the mixed composite tungsten oxide fine particle powder according to any one of claims 1 to 3 is dispersed in a predetermined solvent. The mixture according to claim 4, wherein the value of b * is a positive value when evaluated in an L * a * b * color system (D65 light source / 10-degree field of view) based on JIS Z 8701. Composite tungsten oxide fine particle dispersion. The miscible composite according to claim 4 or 5, wherein the solvent is one or more solvents selected from organic solvents, fats and oils, liquid plasticizers, compounds polymerized by curing, and water. Tungsten oxide fine particle dispersion liquid. An admixture composite tungsten oxide fine particle dispersion according to any one of claims 1 to 3, wherein the admixture composite tungsten oxide fine particle powder is dispersed in a predetermined medium. The mixture according to claim 7, wherein the value of b * is a positive value when evaluated in an L * a * b * color system (D65 light source / 10-degree field of view) based on JIS Z 8701. Composite tungsten oxide fine particle dispersion. The mixed composite tungsten oxide fine particle dispersion according to claim 7, wherein the medium is a resin. The solid resin is one or more resins selected from fluororesins, PET resins, acrylic resins, polyamide resins, vinyl chloride resins, polycarbonate resins, olefin resins, epoxy resins, and polyimide resins. The admixture composite tungsten oxide fine particle dispersion according to any one of claims 7 to 9.

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