JP2011063493A - Near-infrared ray shielding material microparticle dispersion, near-infrared ray shielding body and method for producing near-infrared ray shielding material dispersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near-infrared ray shielding material microparticle dispersion in which composite tungsten oxide microparticles whose coloring power is improved are dispersed in a medium, a near-infrared ray shielding body and a method for producing the near-infrared ray shielding material microparticle dispersion. <P>SOLUTION: The near-infrared ray shielding material microparticle dispersion, which includes near-infrared ray shielding material microparticles dispersed in a medium, is characterized in that the near-infrared ray shielding material microparticle contains composite tungsten oxide microparticles B represented by the formula: LixMyWOz (wherein M is one or more kinds of elements selected from among Cs, Rb, K, Na, Ba, Ca, Sr and Mg; W is tungsten; O is oxygen; 0.1≤x<1.0; 0.1≤y≤0.5; and 2.2≤z≤3.0), the composite tungsten oxide microparticle B is a microparticle having a hexagonal crystal structure and the particle diameter of the near-infrared ray shielding material microparticle is 1-500 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a near-infrared shielding material fine particle dispersion in which oxide material fine particles that are transparent in the visible light region, absorb in the near-infrared region, and have strong coloring power are dispersed in a medium, and the near-infrared shielding material fine particles It is related with the manufacturing method of the near-infrared shielding body manufactured from the dispersion, and a near-infrared shielding material dispersion. Specifically, a near-infrared shielding material fine particle dispersion, a near-infrared shielding material fine particle dispersion, a near-infrared shielding material dispersion, and a near-infrared shielding material dispersion in which near-infrared shielding material fine particles containing composite tungsten oxide fine particles in which lithium is dissolved are dispersed in a medium Regarding the method.

  In recent years, in the fields of various buildings and vehicle window materials, etc., it has been aimed to suppress near-infrared light while sufficiently absorbing visible light, and to suppress indoor temperature rise while maintaining brightness. With the rapid increase in demand for near-infrared shields, development of near-infrared shielding materials, near-infrared shielding glass, and the like has been actively conducted.

  In Patent Document 1, on a transparent glass substrate, at least one metal ion selected from the group consisting of Group IIIa, Group IVa, Group Vb, Group VIb and Group VIIb of the periodic table is provided as a first layer from the substrate side. A composite tungsten oxide is provided, a transparent dielectric film is provided as a second layer on the first layer, and a group IIIa, IVa, Vb, VIb of the periodic table is provided as a third layer on the second layer. And a composite tungsten oxide film containing at least one metal ion selected from the group consisting of group VIIb and group VIIb, and the refractive index of the transparent dielectric film of the second layer is the first layer and the third layer By reducing the refractive index of the composite tungsten oxide film of the layer, a heat ray-shielding glass that can be suitably used in a site where high visible light transmittance and good heat ray shielding performance are required is proposed. To have.

  In Patent Document 2, a first dielectric film is provided as a first layer from the substrate side on a transparent glass substrate in the same manner as Patent Document 1, and tungsten oxide is formed as a second layer on the first layer. There has been proposed a heat ray-shielding glass in which a film is provided and a second dielectric film is provided as a third layer on the second layer.

In Patent Document 3, a composite tungsten oxide film containing the same metal element is provided as a first layer from the substrate side on a transparent substrate by the same method as Patent Document 1, and the second layer is formed on the first layer. Heat ray blocking glass provided with a transparent dielectric film as a layer has been proposed.
In Patent Document 4, tungsten trioxide (WO ₃ ), molybdenum trioxide (MoO ₃ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta) containing an additive material such as hydrogen, lithium, sodium, or potassium. ₂ O ₅ ), a metal oxide film selected from one or more of vanadium pentoxide (V ₂ O ₅ ) and vanadium dioxide (VO ₂ ) is coated with a CVD method or a spray method and thermally decomposed at about 250 ° C. A solar control glass sheet having solar light shielding properties formed in this manner has been proposed.

  In Patent Document 5, sunlight is irradiated by using a tungsten oxide obtained by hydrolyzing tungstic acid and adding an organic polymer having a specific structure called polyvinylprolidone to the tungsten oxide. Then, the ultraviolet rays in the light are absorbed by the tungsten oxide, and excited electrons and holes are generated. The appearance amount of pentavalent tungsten is remarkably increased by a small amount of ultraviolet rays, and the coloring reaction is accelerated. In connection with this, the color density increases, and the property that the pentavalent tungsten is oxidized to hexavalent very quickly by blocking the light and the decoloring reaction is accelerated, the coloring and decoloring reaction to sunlight is performed. It is suggested that an absorption peak appears at a wavelength of 1250 nm in the near-infrared region at the time of coloring, and that a sunlight-modulable light insulating material capable of blocking the near-infrared light of sunlight can be obtained. It is.

  In Patent Document 6, tungsten trichloride is dissolved in alcohol, and the solvent is evaporated as it is, or the solvent is evaporated after heating to reflux, and then heated at 100 ° C. to 500 ° C. Obtaining a powder composed of tungsten or a hydrate thereof or a mixture of both, obtaining an electrochromic device using the tungsten oxide fine particles, forming a multilayer stack, and introducing protons into the film It proposes that the optical properties of the film can be changed.

  Further, Patent Document 7 uses an ammonium metatungstate and various water-soluble metal salts as raw materials and is heated to about 300 to 700 ° C. while being heated with an inert gas (added) MxWO3 (M: metal element such as alkali group Ia, group IIa, rare earth, 0 <x <, by supplying hydrogen gas to which an amount; about 50 vol% or more) or water vapor (addition amount: about 15 vol% or less) is added. Various methods for preparing tungsten bronzes represented by 1) have been proposed.

Further, Patent Document 8 discloses a near-infrared shielding material fine particle dispersion comprising tungsten oxide fine particles and / or composite tungsten oxide fine particles, a near-infrared shielding material, a method for producing near-infrared shielding material fine particles, and a near-infrared shielding material. Fine particles have been proposed.
By the way, the heat ray blocking materials described in Patent Documents 1 to 3 are mainly methods using a dry method such as a sputtering method, a vapor deposition method, an ion plating method and a chemical vapor deposition method (CVD method). Manufactured. For this reason, there exists a subject that a large sized manufacturing apparatus is required and manufacturing cost becomes high. In addition, since the base material of the heat ray blocking material is exposed to high-temperature plasma or needs to be heated after the film formation, when a resin such as a film is used as a base material, the film is separately formed on the equipment. It was necessary to examine the conditions.

  Further, the solar control coated glass sheet described in Patent Document 4 forms a film on the glass by using a CVD method or a combination of a spray method and a thermal decomposition method, but the precursor material is expensive. In the case of using a resin such as a film as a base material because of the fact that it is decomposed at a high temperature, etc., it was necessary to separately examine the film forming conditions.

Furthermore, since the sunlight-modulable light insulating material and the electrochromic element described in Patent Documents 5 to 6 are materials that change the color tone by ultraviolet rays or a potential difference, the structure of the film is complicated and the color tone change is not desired. It was difficult to apply in the field of use.
Furthermore, Patent Document 7 describes a method for preparing tungsten bronze, but there is no description of the particle diameter and optical characteristics of the obtained powder. This is considered to be because the tungsten bronze is used for an electrolysis apparatus, a fuel cell electrode material, and an organic synthesis catalyst material, and not for solar ray shielding as in the present invention.

  On the other hand, compared with the above-described conventional techniques described in Patent Documents 1 to 7, Patent Document 8 proposes tungsten oxide fine particles and / or composite tungsten oxide fine particles used for the production of a near-infrared shield. The oxide fine particles have excellent visible light permeability and good near infrared shielding effect. For this reason, it attracts attention as a near-infrared shield that is suitably used in the fields of various buildings and vehicle window materials.

  However, Patent Document 8 describes tungsten oxide fine particles and / or composite tungsten oxide fine particles, but the coloring power is not fully satisfactory, and there is room for improvement.

JP-A-8-59300 JP-A-8-12378 JP-A-8-283044 JP 2000-1119045 A JP-A-9-127559 JP 2003-121884 A JP-A-8-73223 Japanese Patent No. 4096205

  The present invention has been made in order to solve the above-described problems, and is a large-scale manufacturing apparatus that can transmit visible light sufficiently, does not have a half-miller-like appearance, and forms a film on a substrate. Although not required and high-temperature heat treatment is not required at the time of film formation, near-infrared rays are efficiently shielded by composite tungsten oxide fine particles, and near-infrared shielding material fine particle dispersion, near-infrared shielding material and near-infrared shielding material fine particle dispersion It is to provide a manufacturing method. More specifically, the problem will be described. Near-infrared shielding material fine particle dispersion in which composite tungsten oxide fine particles with improved coloring power are dispersed in a medium, near-infrared shielding material, and method for producing near-infrared shielding material fine particle dispersion The purpose is to provide.

  As a result of continual research conducted by the present inventors in order to solve the above problems, as a fine particle having a near-infrared shielding function, a general formula MyWOz (where M is Cs, Rb, K, Na, Ba, Ca, One or more elements selected from Sr and Mg, W is tungsten, O is oxygen, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) And a general formula LixMyWOz (wherein M is Cs, Rb, One or more elements selected from K, Na, Ba, Ca, Sr, Mg, W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5 2.2 ≦ z ≦ 3.0) After baking the mixture obtained by adding a lithium-containing compound to the above raw material in the air or in an inert gas atmosphere, in a reducing gas atmosphere or in a mixed atmosphere of a reducing gas and an inert gas The composite tungsten oxide (referred to as composite tungsten oxide B for distinction from the composite tungsten oxide A before lithium is dissolved) obtained by heat treatment in FIG. It has been found that the force increases, and when the composite tungsten oxide B is used in the near-infrared shielding material fine particle dispersion, the amount of use can be reduced as compared with the composite tungsten oxide A, and the present invention has been achieved.

That is, the invention according to claim 1
In a near-infrared shielding material fine particle dispersion in which near-infrared shielding material fine particles are dispersed in a medium,
The near-infrared shielding material fine particles have a general formula LixMyWOz (where M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O contains oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) fine particles B of composite tungsten oxide, The fine particles of the composite tungsten oxide B are fine particles having a hexagonal crystal structure, and the near-infrared shielding material fine particles have a particle diameter of 1 nm to 500 nm.

The invention according to claim 2
In the near-infrared shielding material fine particle dispersion according to claim 1,
The near-infrared shielding material fine particles have a general formula MyWOz (where M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O represents oxygen, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0), a mixture of a compound tungsten oxide A represented by lithium and a compound containing lithium in the atmosphere or an inert gas After calcination in an atmosphere, heat treatment is performed in a reducing gas atmosphere or a mixed atmosphere of a reducing gas and an inert gas. General formula LixMyWOz (where M is Cs, Rb, K, Na , Ba, Ca, Sr, and Mg, one or more elements selected from W, tungsten is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2 ≦ z ≦ 3.0) composite tungsten oxide fine particles And it is the particle diameter of the near infrared ray shielding material particles is characterized in that it is a 1 nm to 500 nm.

The invention according to claim 3
In the near-infrared shielding material fine particle dispersion according to claim 2,
The compound having a lithium element is lithium carbonate.

The invention according to claim 4
In the near-infrared shielding material fine particle dispersion according to claim 1,
The medium is a resin or glass.

The invention according to claim 5
In the near-infrared shielding material fine particle dispersion according to claim 4,
The resin is 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. -Any one or more of a sulfonate resin, an acrylic resin, and a polyvinyl butyral resin.
The invention according to claim 6
The near-infrared shielding material fine particle dispersion according to claim 1 is formed in a plate shape or a film shape.
The invention according to claim 7 provides:
In the method for producing a near-infrared shielding material fine particle dispersion in which near-infrared shielding material fine particles are dispersed in a medium,
The near-infrared shielding material fine particles have a general formula MyWOz (where M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O is oxygen, 0.1 ≤ y ≤ 0.5, 2.2 ≤ z ≤ 3.0) as a raw material, fine particles of composite tungsten oxide A, and the general formula LixMyWOz (where M is M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, and Mg, W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) A mixture obtained by adding a lithium-containing compound to the raw material so as to have a composition represented by After firing in a reducing gas atmosphere or a mixture of reducing and inert gases And it can be obtained by heat treatment in 囲気, characterized by distributing to the near infrared ray shielding fine material particles and the medium.

The invention according to claim 8 provides:
The method for producing a near-infrared shielding material fine particle dispersion according to claim 7, wherein the lithium element-containing compound is lithium carbonate.

  According to the present invention, since the coloring power is increased by dissolving lithium in the composite tungsten oxide fine particles, the amount of filler used, that is, while maintaining the original high transparency and solar shading characteristics of the composite tungsten oxide fine particles, Near-infrared shielding material fine particles can be reduced.

The schematic diagram of the crystal structure of the composite tungsten oxide which has a hexagonal crystal. 4 is a TEM image of fine particles in the dispersion according to Example 1. FIG.

  The near-infrared shielding material fine particle dispersion of the present invention is characterized in that near-infrared shielding material fine particles containing composite tungsten oxide fine particles in which lithium is dissolved are dispersed. It is.

1. Near-infrared shielding material fine particles Near-infrared shielding material fine particles according to the present invention having absorption in the near-infrared region,
General formula LixMyWOz (where Li is lithium, M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) Fine particles of composite tungsten oxide B having a hexagonal crystal structure in which lithium is solid-solved It is characterized by comprising.

First, in the composite tungsten oxide represented by the general formula LixMyWOz and the general formula MyWOz, the composition ratio z of oxygen (O) when the composition of tungsten (W) is 1 is shown in parentheses of each general formula. It is 2.2 or more and 3.0 or less. When the composition ratio z is within this range, chemical stability as a material can be obtained, and therefore it can be applied as an effective near-infrared shielding material. The composition ratio y of the element (M) when the composition of tungsten (W) is 1 is 0.1 or more and 0.5 or less from the viewpoint of optical characteristics as shown in parentheses of each general formula. It is necessary to be. When the value of y is less than 0.1, the composite tungsten oxide represented by the general formula LixMyWOz and the general formula MyWOz becomes unstable as a compound, and foreign phases such as WO ₃ and WO ₂ are precipitated. Moreover, although the near-infrared absorption characteristics improve as the value of y increases, the maximum value at which the composite tungsten oxide stably exists as a compound is 0.5 or less, and preferably around 0.33.

Further, when the composite tungsten oxide fine particles represented by the general formulas LixMyWOz and the general formula MyWOz have a hexagonal crystal structure, the transparency of the fine particles is improved in the visible light region and the absorbability in the near infrared region is improved. improves. This will be described with reference to FIG. 1, which is a schematic plan view of the hexagonal crystal structure. In FIG. 1, six octahedrons formed of WO ₆ units denoted by reference numeral 1 are assembled to form a hexagonal void (tunnel), and the element (M) denoted by reference numeral 2 is formed in the void. The unit is arranged to constitute one unit, and a large number of these one units are assembled to form a hexagonal crystal structure.

  When the cation of the element (M) is added to the hexagonal void, the absorption in the near infrared region is improved. Here, generally, when an element (M) having a large ionic radius is added, the hexagonal crystal is formed, which is preferable.

  When the composite tungsten oxide particles having a hexagonal crystal structure have a uniform crystal structure, the addition amount y of the element (M) is not less than 0.1 and not more than 0.5 as described above, and preferably 0.8. It is around 33. When the composition ratio z = 3 of oxygen (O), the value of y is 0.33, so that the element (M) is considered to be disposed in all hexagonal voids.

  It is also effective as a near-infrared shielding material when the composite tungsten oxide B fine particles in which lithium represented by the general formula LixMyWOz has a tetragonal or cubic tungsten bronze structure other than the hexagonal crystal described above. is there. The absorption position in the near-infrared region tends to change depending on the crystal structure of the composite tungsten oxide B fine particles in which lithium is dissolved, and the absorption position in the near-infrared region is longer when it is a tetragonal crystal than a cubic crystal. It moves to the wavelength side, and when it is hexagonal, it tends to move to the longer wavelength side than when it is tetragonal. Further, accompanying the change in the absorption position, the absorption in the visible light region is the smallest in the hexagonal crystal, the next is the tetragonal crystal, and the cubic is the largest among them. Therefore, as described above, it is necessary to use hexagonal tungsten bronze for the purpose of transmitting light in the visible light region and shielding light in the near infrared region. However, the tendency of the optical characteristics described here is merely a rough tendency, and varies depending on the kind of additive element, the amount of addition, and the amount of oxygen, and is not limited to this. Accordingly, a composite tungsten oxide B produced by reacting a composite tungsten oxide A fine particle represented by the general formula MyWOz with a compound having a lithium element such as lithium carbonate and having a solid solution of lithium represented by the general formula LixMyWOz. Even if the fine particles contain some tetragonal or cubic tungsten bronze structures other than the hexagonal crystals described above, they can be used as the near-infrared shielding material of the present invention.

Next, in the composite tungsten oxide B represented by the general formula LixMyWOz, the composition ratio x of lithium (Li) when the composition of tungsten (W) is 1 is shown in parentheses in the general formula. 0.1 ≦ x <1.0. More preferably, x is 0.1 or more, and the sum of x and y in the general formula LixMyWOz is 0.1 ≦ x + y <1.0. In the composite tungsten oxide having a hexagonal crystal structure, when the composition ratio of oxygen (O) is z = 3, other than hexagonal voids formed by assembling six octahedrons formed of the above WO ₆ units In addition, three octahedrons that are also formed in units of WO ₆ are assembled to form a triangular void (tunnel). That is, although there is a site different from the M element, it is considered that lithium is arranged in the triangular void.

  Here, the lithium (Li) is in solid solution means a state in which part or all of the added lithium supplied from the compound having a lithium element is in solid solution. This solid solution state can be confirmed by identifying the crystal phase of the composite tungsten oxide B by X-ray diffraction. That is, when X-ray diffraction of composite tungsten oxide B is performed and only the peak attributed to composite tungsten oxide A is observed, it can be said that all of the added lithium supplied from the compound containing lithium element is in solid solution. .

  By the way, the near-infrared shielding material fine particles according to the present invention composed of the composite tungsten oxide B in which lithium is solid-solved represented by the general formula LixMyWOz particularly absorbs light in the vicinity of a wavelength of 1000 nm, so that the transmission color tone is blue. Become a system. In addition, the particle diameter of the near-infrared shielding material fine particles according to the present invention can be appropriately selected depending on the intended use of the near-infrared shielding material fine particles. First, when used for the purpose of maintaining transparency, it preferably has a particle diameter of 500 nm or less. This is because particles smaller than 500 nm do not completely block light by scattering, and can maintain visibility in the visible light region and at the same time efficiently maintain transparency. In particular, when importance is attached to transparency in the visible light region, it is preferable to further consider scattering by particles.

  When importance is attached to the reduction of scattering by the particles, the particle diameter is 200 nm or less, preferably 100 nm or less. The reason for this is that if the particle diameter of the particles is small, the scattering of light in the visible light region of 400 nm to 780 nm due to geometric scattering or Mie scattering is reduced. This is because it is possible to avoid the adverse effect that transparency cannot be obtained. That is, when the particle diameter is 200 nm or less, the geometric scattering or Mie scattering is reduced, and a Rayleigh scattering region is obtained. This is because in the Rayleigh scattering region, the scattered light decreases in inverse proportion to the sixth power of the particle diameter, so that the scattering is reduced and the transparency is improved as the particle diameter decreases. Furthermore, when the particle diameter is 100 nm or less, the scattered light is preferably extremely small. From the viewpoint of avoiding light scattering, a smaller particle diameter is preferable, and industrial production is possible if the particle diameter is 1 nm or more.

  By selecting the particle diameter of the near-infrared shielding material fine particles according to the present invention to be 500 nm or less, the haze value of the near-infrared shielding material fine particle dispersion obtained by dispersing the near-infrared shielding material fine particles in a medium such as resin or glass is The visible light transmittance can be 85% or less and the haze can be 30% or less. When the haze is greater than 30%, it becomes like frosted glass, and clear transparency cannot be obtained.

  Note that the near-infrared shielding material fine particle surface according to the present invention is coated with an oxide containing one or more elements of Si, Ti, Zr, and Al, which improves the weather resistance of the near-infrared shielding material fine particles. From the viewpoint of making it.

2. Production of near-infrared shielding material fine particles (1) Production of composite tungsten oxide B fine particles represented by general formula LixMyWOz The above general formula LixMyWOz (where Li is lithium, M is Cs, Rb, K, Na, Ba, Ca, One or more elements selected from Sr and Mg, W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3 In order to produce a composite tungsten oxide B fine particle having a hexagonal crystal structure in which lithium is represented by a solid solution, first, the general formula MyWOz (where M is Cs, Rb, K, Na, Ba) , Ca, Sr, Mg, one or more elements, W is tungsten, O is oxygen, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) Composite tungsten oxide A was synthesized and the resulting composite tongue The compound containing lithium element is added to the gusten oxide A fine particles, and the mixture is baked in the atmosphere or in an inert gas atmosphere, and then in a reducing gas atmosphere or a mixed atmosphere of a reducing gas and an inert gas. It can be manufactured by firing (heat treatment).

  When the mixture of the composite tungsten oxide A fine particles and the compound containing lithium element is baked in the atmosphere or an inert gas atmosphere and then baked (heat treatment) in a mixed atmosphere of a reducing gas and an inert gas, Although it will not specifically limit if the density | concentration of the reducing gas in active gas is suitably selected according to baking (heat processing) temperature, Preferably it is 20 vol% or less, More preferably, it is 10 vol% or less, More preferably, it is 7-0.01 vol. %. This is because when the concentration of the reducing gas in the inert gas is 20 vol% or less, rapid reduction of the composite tungsten oxide A fine particles can be avoided.

  The firing temperature may be appropriately selected according to the atmosphere, but when firing a mixture of the composite tungsten oxide A fine particles and the compound containing lithium element in the air, the temperature is higher than 650 ° C. and 1000 ° C. or lower. The firing (heat treatment) temperature in the reducing gas atmosphere or in the mixed atmosphere of reducing gas and inert gas is 400 ° C. or higher and 1000 ° C. or lower, preferably 500 ° C. or higher and 900 ° C. or lower. The firing (heat treatment) time may be appropriately selected according to the amount of treatment, but 5 minutes or more and 10 hours or less is sufficient. In addition, lithium carbonate is desirable for the compound having a lithium element.

  Further, when a mixture of the composite tungsten oxide A fine particles and the compound containing lithium element is baked in an atmosphere of an inert gas alone, it is more than 200 ° C. and less than 600 ° C. from the viewpoint of shortening the manufacturing time and single phase. The temperature is preferably more than 300 ° C. and less than 500 ° C., more preferably more than 350 ° C. and less than 450 ° C.

If the calcination (heat treatment) temperature is too low, it takes time to diffuse lithium atoms, which is not productive. Conversely, if the firing (heat treatment) temperature is too high, a heterogeneous phase is generated. On the other hand, when the mixture of the composite tungsten oxide A fine particles and the compound containing lithium element is fired in the air or in an inert gas atmosphere, and then fired (heat treatment) in a mixed atmosphere of a reducing gas and an inert gas. The temperature at which WO ₂ is not generated may be appropriately selected according to the reducing gas concentration. The firing (heat treatment) time at this time may be appropriately selected according to the selected temperature.

(2) Production of Composite Tungsten Oxide A Fine Particles Represented by General Formula MyWOz Next, the above general formula LixMyWOz (where Li is lithium, M is Cs, Rb, K, Na, Ba, Ca, Sr, Mg) 1 or more elements selected from the above, W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) A raw material for obtaining a composite tungsten oxide B having a hexagonal crystal structure in which lithium is solid-solved, that is, a general formula MyWOz (where M is Cs, Rb, K, Na, Ba, Ca, Sr, One or more elements selected from Mg, W is tungsten, O is oxygen, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) The manufacturing method will be described.

Tungsten acid (H ₂ WO ₄ ), ammonium tungstate, tungsten hexachloride, tungsten hydrate obtained by adding water to tungsten hexachloride dissolved in alcohol and hydrolyzing it, and then evaporating the solvent. As a compound having at least one selected tungsten compound and M element (Cs, Rb, K, Na, Ba, Ca, Sr, Mg), tungstate, chloride, nitrate, sulfate, oxalate , Oxides, carbonates, hydroxides, and other compounds having M element are dry-mixed, and the resulting mixed powder is mixed with an inert gas alone or in a mixed gas atmosphere of an inert gas and a reducing gas. It can be manufactured by one-step firing in steps, or the mixed powder can be fired in a mixed gas atmosphere of inert gas and reducing gas in the first step. An example is a method of producing by two-stage firing in an inert gas atmosphere in the second step. Note that tungsten oxide fine particles may be used instead of the tungsten compound.

Moreover, the following method is illustrated as a manufacturing method different from the said method. That is, as a tungsten compound, hydration of tungsten obtained by adding water to tungstic acid (H ₂ WO ₄ ), ammonium tungstate, tungsten hexachloride, tungsten hexachloride dissolved in alcohol, hydrolyzing it, and then evaporating the solvent. The mixture prepared by wet-mixing one or more tungsten compounds selected from the above and an aqueous solution containing the M element salt is dried to obtain a dried powder, and the resulting dried powder is converted into an inert gas. It is manufactured by firing in one step in a single step or in a mixed gas atmosphere of an inert gas and a reducing gas, or the dried powder is mixed in an inert gas and reducing gas atmosphere in the first step. And a method of producing by performing two-stage firing in which the second step is performed in an inert gas atmosphere. Note that tungsten oxide fine particles may be used instead of the tungsten compound. The salt of the M element is not particularly limited, and examples thereof include nitrates, sulfates, chlorides and carbonates. Moreover, the drying temperature and time at the time of drying the said liquid mixture prepared by wet mixing are not specifically limited.

  When the mixed powder or dry powder is fired in a mixed gas atmosphere of an inert gas and a reducing gas, the concentration of the reducing gas in the inert gas can be selected as appropriate depending on the firing temperature. Although not limited, Preferably it is 20 vol% or less, More preferably, it is 10 vol% or less, More preferably, it is 7-0.01 vol%. This is because when the concentration of the reducing gas in the inert gas is 20 vol% or less, rapid reduction of the tungsten compound in the mixed powder or dry powder can be avoided.

The firing temperature may be appropriately selected depending on the atmosphere, but when the mixed powder or dry powder is fired in an atmosphere of an inert gas alone, the composite tungsten oxide A fine particles represented by the general formula MyWOz are used. From the viewpoint of the crystallinity and coloring power, it exceeds 500 ° C. and is 1200 ° C. or less, preferably 1100 ° C. or less, more preferably 1000 ° C. or less. On the other hand, when the mixed powder or the dried powder is fired in a mixed gas atmosphere of an inert gas and a reducing gas, a temperature at which WO ₂ is not generated may be appropriately selected according to the reducing gas concentration. Furthermore, when producing composite tungsten oxide A fine particles by two-stage firing, firing is performed at 100 ° C. or more and 650 ° C. or less in a mixed gas atmosphere of an inert gas and a reducing gas at the first step. The conditions for firing at over 500 ° C. and below 1200 ° C. in an inert gas atmosphere are exemplified as preferred conditions from the viewpoint of near-infrared shielding properties. The firing treatment time at this time may be appropriately selected according to the firing temperature, but 5 minutes or more and 10 hours or less is sufficient.

Here, tungstic acid (H ₂ WO ₄ ), ammonium tungstate, tungsten hexachloride, tungsten hydrate obtained by adding water to tungsten hexachloride dissolved in alcohol and hydrolyzing it, and then evaporating the solvent, and A compound having M element such as tungstate, chloride, nitrate, sulfate, oxalate, oxide, carbonate, hydroxide, etc., for one or more tungsten compounds selected from tungsten oxide fine particles Is added using the dry mixing method described above, the compound having the element M is preferably an oxide or hydroxide.

  The dry mixing may be performed with a commercially available grinder, kneader, ball mill, sand mill, paint shaker, or the like.

3. Near-infrared shielding material fine particle dispersion and near-infrared shielding material General formula LixMyWOz (where Li is lithium, M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg) W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0). As a method of applying the near-infrared shielding material fine particles according to the present invention composed of the fine particles of the composite tungsten oxide B having the following crystal structure, there is a method in which the fine particles are appropriately dispersed in a medium and formed on a desired substrate surface. is there. This method can be applied to a base material having a low heat-resistant temperature such as a resin material because the near-infrared shielding material fine particles fired at a high temperature in advance can be bound to the base material surface in the base material or by a binder. It is possible and has the advantage of being inexpensive and does not require a large device for formation.

  In addition, since the near-infrared shielding material fine particles according to the present invention composed of fine particles of composite tungsten oxide B have conductivity, when used as a continuous film, they absorb and interfere with radio waves from mobile phones and the like. There is a fear. However, when the near-infrared shielding material fine particles are dispersed in the matrix, since each particle is dispersed in an isolated state, it has radio wave permeability and thus has versatility.

Hereinafter, the near-infrared shielding material fine particle dispersion according to the present invention in which the above-mentioned near-infrared shielding material fine particles are dispersed in a medium, and the near-infrared shielding according to the present invention produced using this near-infrared shielding material fine particle dispersion Explain the body.
(1) Method of dispersing fine particles in a liquid medium and forming a thin film on the surface of the substrate Near-infrared shielding material fine particles obtained by finely pulverizing the near-infrared shielding material according to the present invention are appropriately dispersed in a liquid medium to obtain near-infrared rays. A dispersion liquid of shielding material fine particles is obtained, or a mixture obtained by appropriately mixing the near infrared shielding material fine particles with a solvent is wet pulverized to obtain a dispersion of near infrared shielding material fine particles.

  Then, after adding a resin medium to the obtained dispersion liquid of the near-infrared shielding material fine particles, a coating film is formed by appropriately coating on the surface of the substrate, and then the solvent is evaporated and the resin is cured by a predetermined method. This makes it possible to form a thin film (near-infrared shielding body) in which near-infrared shielding material fine particles are dispersed in a resin medium. The coating method is not particularly limited as long as a resin film (coating film) containing fine particles of near-infrared shielding material can be uniformly coated on the substrate surface. Bar coating method, gravure coating method, spray coating method, dip coating Laws are exemplified. Further, those in which the near-infrared shielding material fine particles are directly dispersed in the binder resin do not need to evaporate the solvent after being applied to the surface of the substrate, and therefore are environmentally and industrially preferable.

  As the resin medium, for example, a UV curable resin, a thermosetting resin, an electron beam curable resin, a room temperature curable resin, a thermoplastic resin, and the like can be appropriately 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 And polyvinyl butyral resin. These resins may be used alone or in combination. Also, a binder using a metal alkoxide can be used. Representative examples of the metal alkoxide include alkoxides such as Si, Ti, Al, and Zr. Binders using these metal alkoxides can form oxide films by hydrolysis and polycondensation by heating or the like.

  Moreover, as said base material with which the dispersion liquid of near-infrared shielding material microparticles | fine-particles etc. are apply | coated, a film or a board may be used if desired, and a 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. Moreover, glass other than resin can be used.

(2) Method of Dispersing Fine Particles in Solid Medium and Forming into Plate (Board) Shape or Film Shape Next, as another method using the near-infrared shielding material fine particles according to the present invention, fine particles are treated as a solid medium (substrate ) May be directly dispersed therein. In order to disperse the fine particles in the solid medium (base material), the fine particles may be permeated from the surface of the base material, or after the base material is melted by raising the temperature to a temperature higher than the melting temperature of the base material, May be mixed. The resin containing near-infrared shielding material fine particles obtained in this way (near-infrared shielding material fine particle dispersion) can be formed into a film or board shape by a predetermined method and applied as a near-infrared shielding body. It is.

  For example, as a method for dispersing near-infrared shielding material fine particles in a PET resin as a solid medium, a dispersion in which the fine particles are dispersed is first prepared by the above-described method, and the PET resin and the fine particle dispersion are mixed. After that, the dispersion liquid is evaporated and then heated to about 300 ° C., which is the melting temperature of the PET resin, and further, the PET resin is melted, mixed, and cooled to produce a PET resin in which fine particles are dispersed. It becomes.

  And the method of grind | pulverizing or disperse | distributing the said near-infrared shielding material microparticles | fine-particles is not specifically limited, For example, ultrasonic irradiation, a bead mill, a sand mill etc. can be used. Moreover, in order to obtain a uniform dispersion, various additives and dispersants may be added, or the pH may be adjusted. The dispersant can be appropriately selected according to the application, and examples thereof include a polymer dispersant, a silane coupling agent, a titanate coupling agent, and an aluminum coupling agent, but are not limited thereto. It is not a thing.

Examples of the present invention will be specifically described below together with comparative examples. However, the present invention is not limited to the following examples. In each example, the visible light transmittance and the solar radiation transmittance were measured using a spectrophotometer U-4000 manufactured by Hitachi, Ltd. and calculated based on JIS R 3106. In the film evaluation, the film was formed with three types of bar coaters with different wire diameters, and the amount of filler used (g / m 2) and visible when the solar transmittance was 40% from the three-point plot of the film. The light transmittance was determined. The amount of filler used was calculated by cutting a PET (polyethylene terephthalate) film before and after film formation into a certain size and measuring its weight.
In addition, the measurement wavelength range of visible light transmittance is 380 nm to 780 nm, and the measurement wavelength range of solar transmittance is 200 nm to 2600 nm.

[Example 1]
After adding 45.30 g of tungstic acid to an aqueous solution in which 9.75 g of cesium carbonate was dissolved in 25 g of water, the mixture was dried at 105 ° C. to obtain a dry powder. Next, the dry powder is heated while supplying 1.6% H ₂ gas using N ₂ gas as a carrier, and heat-treated at a temperature of 800 ° C. for 1 hour to obtain Cs _0.33 WO ₃ fine particles. Obtained. As a result of identifying the crystal phase by powder X-ray diffraction of the fired powder, it was confirmed that it was a Cs _0.33 WO ₃ single phase. It is thought that lithium is dissolved.

Next, after 10 g of the fine particles and 0.268 g of lithium carbonate were sufficiently mixed in a crusher, the mixture was heat-treated at 800 ° C. for 6 hours in the atmosphere, and further 20 minutes in a 1.6% H ₂ / N ₂ atmosphere. Li _0.2 Cs _0.33 WO ₃ fine particles a were obtained by heat treatment. As a result of identifying the crystal phase by powder X-ray diffraction of the calcined powder, it was found that it was Cs _0.3 WO ₃ single phase (hexagonal crystal). Thus, _{then, Cs 0.33} WO ₃ and _Li 0.2 _{Cs 0.33} WO ₃ such that 8% by weight in terms of, polymeric dispersing agent 8% by weight (solid content: 40%), toluene Dispersion A was obtained by weighing 84% by weight and pulverizing and dispersing with a paint shaker containing 0.3 mmφZrO ₂ beads for 8 hours. The particle diameter of the Li _0.2 Cs _0.33 WO ₃ fine particles in the dispersion was 100 nm or less, as is apparent from the TEM image in FIG.

Next, 66.7% by weight of the above dispersion (liquid A) and 33.3% by weight of UV curable resin [UV3701 manufactured by Toa Gosei Co., Ltd.] were mixed well and Li _0.002 Cs _0.33 WO ₃ A coating solution containing fine particles (composite tungsten oxide B fine particles) was prepared, and three kinds of bar coaters (that is, bars of counts 14, 24, and 30) having different wire diameters were used on a glass substrate having a thickness of 3 mm. The coating solution is applied to form three types of coatings with different thicknesses, and after drying for one minute at 70 ° C to evaporate the solvent, the coating is irradiated with ultraviolet rays using a high-pressure mercury lamp. A near-infrared shield 1 according to Example 1 was obtained. Table 1 shows the visible light transmittance and filler usage of the near-infrared shield 1.

[Example 2]
As in Example 1, except that 0.133 g of lithium carbonate was added instead of the condition of Example 1 in which 2.68 × 10 ⁻³ g of lithium carbonate was added to 10 g of Cs _0.33 WO ₃ fine particles. Thus, Li _0.10 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) according to Comparative Example 2 were produced.

As a result of identifying the crystal phase of the calcined powder according to Example 2 by X-ray diffraction, only a peak attributed to Cs _0.33 WO ₃ was observed. It is thought that lithium is dissolved.
As in Example 1, the visible light transmittance and filler usage of the near-infrared shield 2 according to Example 2 are shown in Table 1.

[Comparative Example 1]
The near-infrared shielding material according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the Cs _0.33 WO ₃ fine particles (composite tungsten oxide A fine particles) produced in Example 1 were applied as the near-infrared shielding material fine particles. Manufactured.

Incidentally, the Cs _0.33 WO ₃ fine particles according to Comparative Example 1 were Cs _0.33 WO ₃ single phase as in Example 1.
_Further, to obtain dispersion prepared in the same manner as in Example 1 so that the _{Cs 0.33} WO ₃ fine particles 8 weight percent (A solution).
As in Example 1, Table 1 shows the visible light transmittance and filler usage of the near-infrared shield 3 according to Comparative Example 1.

[Evaluation]
From the results shown in Table 1, the near-infrared shields 1 and 2 according to Examples 1 and 2 and the near-infrared shield 3 according to Comparative Example 1 were compared.

As a result, the near-infrared shields 1 and 2 have a filler usage of 1.4 g / m ² or less, while the visible high transmittance is 70% or more when the solar radiation transmittance is 40%. On the other hand, the near-infrared shield 3 according to Comparative Example 1 has a filler usage of more than 1.5 g / m ^{2 even though} the visible high transmittance is 70% or more when the solar transmittance is 40%. It was. That is, in Examples 1 and 2, it was shown that the amount of the near-infrared shielding material fine particles used was reduced compared to Comparative Example 1, and the near-infrared shielding material fine particles (composite tungsten oxide B) used in the present invention were reduced. This shows that the coloring power is improved as compared with the conventional composite tungsten oxide A.

  INDUSTRIAL APPLICABILITY The present invention is suitably used when an infrared shielding effect is imparted to window materials and electronic devices used in the construction field, transportation equipment field, and the like.

1 WO ₆ units 2 Element (M)

Claims (8)

In a near-infrared shielding material fine particle dispersion in which near-infrared shielding material fine particles are dispersed in a medium,
The near-infrared shielding material fine particles have a general formula LixMyWOz (where M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O contains oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0), and composite tungsten oxide fine particles B represented by
The fine particles of the composite tungsten oxide B are fine particles having a hexagonal crystal structure;
The near-infrared shielding material fine particle dispersion, wherein the near-infrared shielding material fine particles have a particle diameter of 1 nm to 500 nm. In a near-infrared shielding material fine particle dispersion in which near-infrared shielding material fine particles are dispersed in a medium,
The near-infrared shielding material fine particles have a general formula MyWOz (where M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O represents oxygen, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0), a mixture of a compound tungsten oxide A represented by lithium and a compound containing lithium in the atmosphere or an inert gas After calcination in an atmosphere, heat treatment is performed in a reducing gas atmosphere or a mixed atmosphere of a reducing gas and an inert gas. General formula LixMyWOz (where M is Cs, Rb, K, Na , Ba, Ca, Sr, and Mg, one or more elements selected from W, tungsten is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2 ≦ z ≦ 3.0) composite tungsten oxide fine particles And it is,
The near-infrared shielding material fine particle dispersion according to claim 1, wherein the near-infrared shielding material fine particles have a particle diameter of 1 nm to 500 nm.   The near-infrared shielding material fine particle dispersion according to claim 2, wherein the compound having a lithium element is lithium carbonate.   The near-infrared shielding material fine particle dispersion according to any one of claims 1 to 3, wherein the medium is resin or glass.   The resin is 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. The near-infrared shielding material fine particle dispersion according to claim 4, wherein the near-infrared shielding material fine particle dispersion is one or more of a sulfonate resin, an acrylic resin, and a polyvinyl butyral resin.   The near-infrared shielding material according to claim 1, wherein the near-infrared shielding material fine particle dispersion is formed into a plate shape or a film shape. In the method for producing a near-infrared shielding material fine particle dispersion in which near-infrared shielding material fine particles are dispersed in a medium,
The near-infrared shielding material fine particles have a general formula MyWOz (where M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O is oxygen, 0.1 ≤ y ≤ 0.5, 2.2 ≤ z ≤ 3.0) as a raw material, fine particles of composite tungsten oxide A, and the general formula LixMyWOz (where M is M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, and Mg, W is tungsten, O is oxygen, 0.1 ≦ x <1.0, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) A mixture obtained by adding a lithium-containing compound to the raw material so as to have a composition expressed as ≦ y ≦ 0.5, in air or in an inert gas atmosphere After firing in a reducing gas atmosphere or a mixed atmosphere of reducing gas and inert gas. And it can be obtained by heat treatment in mind,
A method for producing a near-infrared shielding material fine particle dispersion, wherein the near-infrared shielding fine material particles are dispersed in a medium.   The method for producing a near-infrared shielding material fine particle dispersion according to claim 7, wherein the compound having a lithium element is lithium carbonate.