JP2011063484A - Near-infrared ray shielding material microparticle, method for producing the same, near-infrared ray shielding material microparticle dispersion and near-infrared ray shielding body - Google Patents

Abstract

Disclosed are a near-infrared shielding material fine particle with improved heat resistance and moist heat resistance, a near-infrared shielding material fine particle dispersion in which the fine particle is dispersed, and the like.
The near-infrared shielding material fine particles have a general formula LixMyWOz (Li is lithium, M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, and Mg, W Is composed of tungsten, O is oxygen, 0.0001 ≦ x <0.1, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0), which is composed of fine particles of composite tungsten oxide B having a hexagonal crystal structure in which lithium is solid-solved. The ratio of lattice constants c / a is represented by the general formula MyWOz (M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, Mg, W is tungsten, O is Oxygen, which is larger than the lattice constant ratio c / a of the composite tungsten oxide A expressed by 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0), and its numerical value is 1.027300 to 1.029000.
[Selection] Figure 1

Description

  The present invention relates to a near-infrared shielding material fine particle that is transparent in the visible light region and absorbs in the near-infrared region, a method for producing the same, and a near-infrared shielding material fine particle in which near-infrared shielding material fine particles are dispersed in a medium. Dispersion and near-infrared shielding material produced from this near-infrared shielding material fine particle dispersion, and in particular, near-infrared shielding material fine particles with improved heat and moisture resistance, a method for producing the same, and near-infrared shielding material fine particle dispersion Body and near-infrared shield.

  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.

  For example, in Patent Document 1, on a transparent glass substrate, at least one selected from the group consisting of IIIa group, IVa group, Vb group, VIb group and VIIb group of the periodic table as the first layer from the substrate side. A composite tungsten oxide film containing metal ions is provided, a transparent dielectric film is provided as a second layer on the first layer, and a group IIIa of the periodic table is provided as a third layer on the second transparent dielectric film, A composite tungsten oxide film containing at least one metal ion selected from the group consisting of IVa group, Vb group, VIb group and VIIb group is provided, and the refractive index of the transparent dielectric film constituting the second layer Is made lower than the refractive index of the composite tungsten oxide film of the first layer and the third layer, and a heat ray-shielding glass that can be suitably used for a portion requiring high visible light transmittance and good heat ray shielding performance is proposed. ing.

  Further, 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 the second layer is oxidized on the first layer. There has been proposed a heat ray-shielding glass in which a tungsten film is provided and the second-layer 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 the transparent substrate by the same method as Patent Document 1, and the first layer is formed on the first layer. Heat ray blocking glass having a transparent dielectric film as two layers has been proposed.

Further, in Patent Document 4, tungsten trioxide (WO ₃ ), molybdenum trioxide (MoO ₃ ), niobium pentoxide (Nb ₂ O ₅ ), and tantalum pentoxide containing additional elements such as hydrogen, lithium, sodium, and potassium. A metal oxide film selected from one or more of (Ta ₂ O ₅ ), vanadium pentoxide (V ₂ O ₅ ), and vanadium dioxide (VO ₂ ) is coated on a glass sheet by a CVD method or a spray method, and 250 A solar control glass sheet having solar light shielding properties formed by thermal decomposition at about ° C. has been proposed.

  In Patent Document 5, a tungsten oxide obtained by hydrolyzing tungstic acid is used, and an organic polymer having a specific structure called polyvinylpyrrolidone is added to the tungsten oxide, so that when sunlight is irradiated, Is absorbed by the tungsten oxide to generate excited electrons and holes, and the appearance of pentavalent tungsten is remarkably increased by a small amount of ultraviolet light, and the coloring reaction is accelerated. In addition, the property that the pentavalent tungsten is oxidized to hexavalent very quickly by blocking the light and the decoloring reaction becomes fast, and the coloring and decoloring reaction to sunlight is fast. There has been proposed a sunlight-modulable light-insulating material that has an absorption peak at 1250 nm and can block near-infrared rays of sunlight.

  In Patent Document 6, tungsten trichloride or its solvent is obtained by dissolving tungsten hexachloride in alcohol and evaporating the solvent as it is, or evaporating the solvent after heating to reflux, and then heating at 100 ° C. to 500 ° C. Obtaining a powder composed of a hydrate or a mixture of both, obtaining an electrochromic device using the tungsten oxide fine particles, forming a multilayer structure, and introducing an optical film into the film when protons are introduced. It has been proposed that the characteristics can be changed.

Further, in Patent Document 7, meta-type ammonium tungstate and various water-soluble metal salts are used as raw materials, and heated to about 300 to 700 ° C., the inert gas (addition amount; about By supplying a hydrogen gas to which 50 vol% or more or water vapor (added amount; about 15 vol% or less) is added, M _x WO ₃ (M: metal element such as alkali group Ia, group IIa, rare earth, 0 <x Methods for preparing various tungsten bronzes represented by <1) have been proposed.

  Further, Patent Document 8 discloses a near-infrared shielding material fine particle dispersion in which near-infrared shielding material fine particles composed of tungsten oxide fine particles and / or composite tungsten oxide fine particles are dispersed in a medium such as resin or glass. A near-infrared shielding body produced from a dispersion, a method for producing the above-mentioned near-infrared shielding material fine particles, and near-infrared shielding material fine particles have been proposed.

  By the way, the near-infrared shielding body (heat ray shielding glass) described in Patent Documents 1 to 3 is mainly a dry type by a vacuum film forming method such as a sputtering method, a vapor deposition method, an ion plating method and a chemical vapor deposition method (CVD method). Since it is manufactured by the method using the method, there is a problem that a large manufacturing apparatus is required and the manufacturing cost is increased. In addition, since the near-infrared shielding base material is exposed to high-temperature plasma or requires heating after film formation because it is manufactured by the above method, a resin such as a film is used instead of glass. In the case of using it as a base material, it was necessary to separately examine the film forming conditions on equipment.

  Moreover, the near-infrared shielding body (solar control glass sheet) described in Patent Document 4 forms a metal oxide film as a raw material on glass by a CVD method or a combination of a spray method and a thermal decomposition method. Since the precursor raw material is expensive and decomposes at high temperature, it is necessary to separately examine the film forming conditions when using a resin such as a film instead of a glass sheet as a base material. .

  Moreover, since the sunlight-modulable light heat insulating material described in Patent Document 5 and the electrochromic element described in Patent Document 6 are materials that change their color tone by ultraviolet rays or a potential difference, the structure of the film is complicated, There is a problem that is difficult to apply in the field of use where color change is not desired.

  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 because, in Patent Document 7, tungsten bronze is considered to be an electrolysis device, a fuel cell electrode material, and an organic synthesis catalyst material, and the above-described near-infrared shield is not used.

  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, there are cases where these composite tungsten oxide fine particles are not sufficiently satisfied with respect to heat resistance and heat and moisture resistance, and there is still 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 paying attention to such problems, and the object of the present invention is to provide near-infrared shielding material fine particles (composite tungsten oxide fine particles) with improved heat resistance and heat-and-moisture resistance and a method for producing the same. In addition, another object is to provide a near-infrared shielding material fine particle dispersion in which the near-infrared shielding material fine particles (composite tungsten oxide fine particles) are dispersed in a medium and a near-infrared shielding body.

  Therefore, in order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, the general formula MyWOz (where M is selected from Cs, Rb, K, Na, Ba, Ca, Sr, and Mg). One or more elements, W is tungsten, O is oxygen, composite tungsten oxide represented by 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) The compound of general formula LixMyWOz (where Li is lithium, M is Cs, Rb) produced by reacting a compound having a lithium element such as lithium carbonate with a compound tungsten oxide A for distinction from the composite tungsten oxide formed. , K, Na, Ba, Ca, Sr, Mg, one or more elements, W is tungsten, O is oxygen, 0.0001 ≦ x <0.1, 0.1 ≦ y ≦ 0. 5, 2.2 ≦ z ≦ 3.0 Is a composite tungsten oxide having a hexagonal crystal structure in which lithium is represented by the following formula (referred to as composite tungsten oxide B to distinguish it from the composite tungsten oxide A before lithium is dissolved): -It has been found that the heat and moisture resistance is excellent, and the near-infrared shielding material fine particle dispersion in which the composite tungsten oxide B is dispersed and the near-infrared shield are also excellent in the heat and moisture resistance. I came to discover that. The present invention has been completed based on such technical findings.

That is, the invention according to claim 1
In the near-infrared shielding material fine particles 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, 0.0001 ≦ x <0.1, 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 The lattice constant ratio c / a is represented by the 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) is larger than the lattice constant ratio c / a of the composite tungsten oxide A, and the numerical value is 1.027300-1.029000,
The invention according to claim 2
In the near-infrared shielding material fine particles according to the invention of claim 1,
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) and a mixture of a compound having a lithium element and a compound having a lithium element is calcined in the atmosphere or in an inert gas atmosphere, and then reduced gas. It is obtained by heat treatment in an atmosphere or a mixed atmosphere of a reducing gas and an inert gas,
The invention according to claim 3
In the near-infrared shielding material fine particles according to the invention of claim 2,
The compound having a lithium element is lithium carbonate.

Next, the invention according to claim 4 is:
In the manufacturing method of near-infrared shielding material fine particles having absorption in the near-infrared region,
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, and the general formula LixMyWOz (where Li is lithium, M is Cs, Rb, K, Na, One or more elements selected from Ba, Ca, Sr, and Mg, W is tungsten, O is oxygen, 0.0001 ≦ x <0.1, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) A compound having lithium element is added to the raw material so as to have a composition represented by ≦ z ≦ 3.0), and the mixture is fired in the atmosphere or in an inert gas atmosphere, and then in a reducing gas atmosphere. Or heat treatment in a mixed atmosphere of reducing gas and inert gas, Characterized in that to produce the near infrared ray shielding material fine particles according to claim 1,
The invention according to claim 5
In the manufacturing method of the near-infrared shielding material fine particles according to the invention of claim 4,
The compound having a lithium element is lithium carbonate.

The invention according to claim 6
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 the general formula LixMyWOz (where Li is lithium, M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, and Mg, and W is tungsten. , O is oxygen, 0.0001 ≦ x <0.1, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) and a hexagonal crystal structure in which lithium is dissolved. It is composed of fine particles of composite tungsten oxide B having a lattice constant ratio c / a selected from the general formula MyWOz (where M is selected from 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) Ratio of lattice constant of composite tungsten oxide A c / larger than a and the numerical value is 1.027300 to 1.029000 And characterized in that the particle diameter is 1nm or more 500nm or less,
The invention according to claim 7 provides:
In the near-infrared shielding material fine particle dispersion according to the invention of claim 6,
The medium in which the near-infrared shielding material fine particles are dispersed is a resin or glass,
The invention according to claim 8 provides:
In the near-infrared shielding material fine particle dispersion according to the invention of claim 7,
The resin is a 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, It is one or more types selected from polyvinyl butyral resins.

The invention according to claim 9 is
In the near-infrared shield,
The near-infrared shielding material fine particle dispersion according to any one of claims 6 to 8 is formed in a plate shape, a film shape, or a thin film shape.

  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, 0.0001 ≦ x <0.1, 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 The lattice constant ratio c / a is represented by the 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) is larger than the lattice constant ratio c / a of the composite tungsten oxide A, and the numerical value is Near-infrared shielding material according to the present invention which is 1.027300 to 1.029000 According to particles, it is very excellent in heat-wet heat resistance compared with the conventional near-infrared shielding material.

  Therefore, it is possible to exhibit excellent heat resistance and moist heat resistance while maintaining the conventional high visible light transmission performance and near infrared absorption performance.

  Similarly, a near-infrared shielding material fine particle dispersion according to the present invention, in which fine particles of the composite tungsten oxide B having a hexagonal crystal structure in which lithium represented by the general formula LixMyWOz is dissolved, and the The near-infrared shielding body according to the present invention produced from the near-infrared shielding material fine particle dispersion can also exhibit excellent heat and moisture resistance.

The schematic diagram of the crystal structure of the composite tungsten oxide which has a hexagonal crystal. The schematic diagram of the hexagonal close-packed lattice for demonstrating ratio c / a of a lattice constant.

  Hereinafter, embodiments of the present invention will be described in detail.

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, 0.0001 ≦ x <0.1, 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 The lattice constant ratio c / a is represented by the 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) is larger than the lattice constant ratio c / a of the composite tungsten oxide A, and the numerical value is 1.027300 to 1.029000.

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. 0.0001 ≦ x <0.1. 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.

  And the ratio c / a of the lattice constant in the composite tungsten oxide B represented by the general formula LixMyWOz (see the hexagonal close-packed lattice symbols a and c shown in the schematic diagram of FIG. 2) is a compound containing a lithium element. It is confirmed that the lattice constant ratio c / a of the composite tungsten oxide A represented by the general formula MyWOz before the reaction is larger than the lattice constant ratio c / a of the composite tungsten oxide B represented by LixMyWOz. Therefore, it is considered that lithium (Li) is in solid solution. More specifically, the ratio c / a of the lattice constant in the composite tungsten oxide B expressed by the general formula LixMyWOz is the ratio c of the lattice constant of the composite tungsten oxide A expressed by the general formula MyWOz as the starting material. More than 0.000050 compared to / a. On the other hand, the upper limit of the difference between the lattice constant ratio c / a of the composite tungsten oxide B and the lattice constant ratio c / a of the starting composite tungsten oxide A is 0.001700 or less. The reason why the upper limit is 0.001700 or less is that the lattice constant ratio c / a of the composite tungsten oxide B is larger than the lattice constant ratio c / a of the starting composite tungsten oxide A by more than 0.001700. This is because the lattice constant ratio c / a becomes excessive, the element (M), which will be described later, is easily desorbed, and the heat resistance and moist heat resistance are lowered. And the ratio c / a of the lattice constant of the composite tungsten oxide B expressed by the general formula LixMyWOz needs to be 1.027300 to 1.029000.

  Further, the c-axis of the lattice constant in the composite tungsten oxide B represented by the general formula LixMyWOz is also the c-axis of the lattice constant of the composite tungsten oxide A represented by the general formula MyWOz before reacting with the compound having a lithium element. It is considered that lithium (Li) is in a solid solution also from the fact that it has been confirmed that it is more elongated. 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.

  By the way, regarding the composite tungsten oxide B in which lithium represented by the general formula LixMyWOz is solid-solved, the reason why the heat resistance / humidity and heat resistance are improved as compared with the composite tungsten oxide A represented by the general formula MyWOz at present. Although it is unknown, the present inventors infer as follows.

First, the presence of water in the atmosphere of the composite tungsten oxide A is deeply related to the deterioration (heat resistance / moisture and heat resistance) phenomenon of the composite tungsten oxide A represented by the general formula MyWOz under wet and high temperature conditions. This has been confirmed by the present inventors. The composite tungsten oxide A represented by the general formula MyWOz is an acidic oxide like WO ₃ and is unstable in moisture. When WO ₃ is immersed in water, the W component is eluted and the pH is lowered. When the composite tungsten oxide A represented by the general formula MyWOz is immersed in water, the W component is similarly eluted and the pH is lowered. At this time, when the element (M) is a basic element such as Cs, Rb, K, Na, Ba, Ca, Sr, etc., the elution of the element (M) is promoted in the form of neutralizing the acidic aqueous solution. It is considered that the infrared absorption ability is lowered. Further, even when moisture is not involved, it is expressed by the general formula MyWOz that desorption of the element (M) occurs in the composite tungsten oxide A expressed by the general formula MyWOz exposed at a high temperature. This is confirmed by the change in the ratio c / a of the lattice constant before and after the composite tungsten oxide A was exposed to a high-temperature dry air atmosphere. On the other hand, in the composite tungsten oxide B represented by the general formula LixMyWOz, it is considered that elution and desorption of the element (M) are suppressed because lithium (Li) is in solid solution. From such an idea, when the lithium (Li) composition ratio x of the composite tungsten oxide B represented by the general formula LixMyWOz is less than 0.0001, the amount of Li that suppresses elution and desorption of the element (M) is small. Insufficient durability of the composite tungsten oxide B cannot be obtained. On the other hand, when the lithium (Li) composition ratio x is 0.1 or more, the durability (heat resistance / moisture heat resistance) of the composite tungsten oxide B is deteriorated. Although the details of this reason are not clear, it is presumed that the element (M) is easily desorbed when the ratio c / a of the lattice constants becomes excessive as Li increases.

  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, 0.0001 ≦ x <0.1, 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) The composite tungsten oxide A was synthesized and the resulting composite A compound containing lithium element is added to the tungsten 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. Can be produced 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, 0.0001 ≦ x <0.1, 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, 0.0001 ≦ x <0.1, 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.

  Hereinafter, examples of the present invention will be specifically described with reference to comparative examples, but the present invention is not limited to the following examples.

  Here, in each Example, the visible light transmittance and the solar radiation transmittance of the near-infrared shield were measured using “Spectrophotometer U-4000” manufactured by Hitachi, Ltd., and based on JIS R 3106. Calculated. In addition, film evaluation (that is, evaluation of a near-infrared shielding material fine particle dispersion in which composite tungsten oxide fine particles B in which lithium is dissolved) is dispersed is a mixed liquid (coating liquid) having near-infrared shielding material fine particles and an ultraviolet curable resin. Measure the visible light transmittance and solar radiation transmittance of three kinds of near-infrared shielding material fine particle dispersions obtained by using three types of bar coaters with different wire diameters and having different film thicknesses. In addition, the solar radiation (wavelength range 200 nm to 2600 nm) transmittance when the visible light (wavelength range 380 nm to 780 nm) transmittance is 70% is obtained from the three-point plot of the film (near-infrared shielding material fine particle dispersion).

[Example 1]
An aqueous solution in which 7.43 kg of cesium carbonate was dissolved in 6.70 kg of water was added to 34.57 kg of tungstic acid (H ₂ WO ₄ ). After mixing, water was removed while stirring at 100 ° C. to dry powder. Got.

Next, while supplying 5% H ₂ gas with N ₂ gas as a carrier (that is, in a mixed gas atmosphere of an inert gas and a reducing gas), the dry powder is heated and heated at a temperature of 800 ° C. After baking for 5.5 hours, Cs _0.33 WO ₃ fine particles (that is, composite tungsten oxide A fine particles) were obtained. As a result of identifying the crystal phase of the calcined powder obtained by the calcining treatment by X-ray diffraction, it was Cs _0.33 WO ₃ single phase, and the lattice constant ratio c / a was 1.027547.

Next, 10 g of the above-mentioned Cs _0.33 WO ₃ fine particles and 2.68 × 10 ⁻³ g of lithium carbonate were sufficiently mixed in a crusher and baked in the atmosphere at 800 ° C. for 6 hours, and then N ₂ Li _0.002 Cs _0.33 WO ₃ fine particles (that is, composite tungsten oxide B fine particles) by heat-treating at 800 ° C. for 20 minutes while supplying 1.6% H ₂ gas using a gas as a carrier. Manufactured. As a result of identifying the crystal phase of the calcined powder by X-ray diffraction, only the peak attributed to Cs _0.33 WO ₃ was observed. The ratio c / a of the lattice constant is 1.027630, which is larger than the ratio c / a of the lattice constant of the Cs _0.33 WO ₃ fine particles not containing lithium, and lithium is dissolved. It was confirmed that

Next, 8% by weight of the above Li _0.002 Cs _0.33 WO ₃ fine particles (8% by weight in terms of Cs _0.33 WO ₃ ), 8% by weight of a polymeric dispersant (solid content 40%), toluene 84 Dispersion in which Li _0.002 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) are dispersed by weighing and weighting in a paint shaker containing 0.3 mmφZrO ₂ beads for 8 hours. A liquid (liquid A) was obtained. The particle diameter of the Li _0.002 Cs _0.33 WO ₃ fine particles in the dispersion (liquid A) was 10 to 50 nm as a result of TEM observation.

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 according to Example 1 was obtained.

  When the optical characteristics of the near-infrared shield according to Example 1 were measured, the solar radiation transmittance was 32.9% and the haze was 0.5% when the visible light transmittance was 70%. Therefore, the near-infrared shield according to Example 1 can be suitably used as a near-infrared shield that is transparent in the visible light region and has absorption in the near-infrared region.

  Next, in order to investigate the heat resistance of the near-infrared shield according to Example 1, an accelerated deterioration test was performed.

  That is, after forming a film on the glass substrate using the coating solution so that the initial visible light transmittance is 70%, the glass substrate is exposed to an air atmosphere at 120 ° C., and after 72 hours. The change rate of visible light transmittance (hereinafter referred to as ΔVLT) and the change rate of solar radiation transmittance (hereinafter referred to as ΔST) were examined. Hereinafter, the accelerated deterioration test exposed to an air atmosphere at 120 ° C. is abbreviated as a heat resistance test, and is represented as “heat resistance” in Table 1.

  As a result, ΔVLT after 72 hours in the heat resistance test was 2.27% and ΔST after 72 hours was 1.36%, confirming the improvement in heat resistance as compared with Comparative Example 1 described below.

  Furthermore, after forming a film on the PET (polyethylene terephthalate) film having a thickness of 50 μm so as to have an initial visible light transmittance of 70% using the coating solution, the PET film was subjected to an atmosphere of 80 ° C. and 95% RH. ΔVLT and ΔST were measured 72 hours after exposure. Hereinafter, the accelerated deterioration test exposed in an atmosphere of 80 ° C. and 95% RH is abbreviated as a “moisture heat resistance test” and is expressed as “moisture heat resistance” in Table 1.

  As a result, ΔVLT after 72 hours in the heat and humidity resistance test was 2.95%, and ΔST after 72 hours was 1.80%, confirming an improvement in heat and humidity resistance compared to Comparative Example 1 described below. .

[Example 2]
In place 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, except that 6.71 × 10 ⁻³ g of lithium carbonate was added. In the same manner as in Example 1, Li _0.005 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) according to Example 2 were produced.

In addition, as a result of identification of the crystal phase by X-ray diffraction of the baked powder according to Example 2, only a peak attributed to Cs _0.33 WO ₃ was observed. The ratio c / a of the lattice constant is 1.027659, which is larger than the ratio c / a of the lattice constant of the Cs _0.33 WO ₃ fine particles not containing lithium, and the lithium is dissolved. It was confirmed that

_{Also, Li 0.005 Cs 0.33 WO 3 Li} 0.005 fine particles dispersion was prepared in the same manner as in Example 1 so as to be 8% by weight _{Cs 0.33} WO ₃ terms (A solution) in The particle diameter of the Cs _0.33 WO ₃ fine particles was 10 to 50 nm as a result of TEM observation.

  And as in Example 1, when the optical characteristics of the near-infrared shield according to Example 2 were measured, the solar radiation transmittance was 33.1% and the haze was 0.4% when the visible light transmittance was 70%. there were.

  In addition, ΔVLT after 72 hours in the heat resistance test was 2.13%, and ΔST after 72 hours was 1.35%, confirming improvement in heat resistance as compared with Comparative Example 1 described below. Note that the wet heat resistance test was not performed in Example 2.

[Example 3]
In place 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, except that 1.34 × 10 ⁻² g of lithium carbonate was added. In the same manner as in Example 1, Li _0.010 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) according to Example 3 were produced.

In addition, as a result of identification of the crystal phase by X-ray diffraction of the baked powder according to Example 3, only a peak attributed to Cs _0.33 WO ₃ was observed. Further, the ratio c / a of the lattice constant is 1.027798, which is larger than the ratio c / a of the lattice constant of the Cs _0.33 WO ₃ fine particles not containing lithium, and the lithium is dissolved. It was confirmed that

_{Also, Li 0.010 Cs 0.33 WO 3 Li} 0.010 fine particles dispersion was prepared in the same manner as in Example 1 so as to be 8% by weight _{Cs 0.33} WO ₃ terms (A solution) in The particle diameter of the Cs _0.33 WO ₃ fine particles was 10 to 50 nm as a result of TEM observation.

  And as in Example 1, when the optical characteristics of the near-infrared shield according to Example 3 were measured, the solar radiation transmittance was 33.3% and the haze was 0.4% when the visible light transmittance was 70%. there were.

  In addition, ΔVLT after 72 hours in the heat resistance test was 1.98%, and ΔST after 72 hours was 1.26%, confirming an improvement in heat resistance as compared with Comparative Example 1 described below. In Example 3, the wet heat resistance test was not performed.

[Example 4]
Li _0.002 Cs _0.33 WO ₃ fine particles 8 wt% (Cs _0.33 WO ₃ equivalent 8 wt%), polymer dispersant (solid content 40%) 8 wt%, toluene 84 wt% The same as Example 1 except that the pulverization / dispersion treatment time with the paint shaker was changed to 6 hours instead of the conditions of Example 1 weighed and pulverized / dispersion treatment with the paint shaker containing 0.3 mmφZrO ₂ beads for 8 hours. Then, a dispersion (Liquid A) according to Example 4 in which Li _0.002 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) were dispersed was prepared.

The particle diameter of the Li _0.002 Cs _0.33 WO ₃ fine particles in the dispersion (liquid A) prepared in the same manner as in Example 1 was 70 to 110 nm as a result of TEM observation.

  And as in Example 1, when the optical characteristics of the near-infrared shield according to Example 4 were measured, the solar radiation transmittance was 33.9% and the haze was 0.6% when the visible light transmittance was 70%. there were.

  In addition, ΔVLT after 72 hours in the heat resistance test was 2.22% and ΔST after 72 hours was 1.29%, confirming the improvement in heat resistance as compared with Comparative Example 1 described below. In Example 4, the wet heat resistance test was not performed.

[Example 5]
Li _0.002 Cs _0.33 WO ₃ fine particles 8 wt% (Cs _0.33 WO ₃ equivalent 8 wt%), polymer dispersant (solid content 40%) 8 wt%, toluene 84 wt% The same as Example 1 except that the pulverizing / dispersing time by the paint shaker was changed to 4 hours instead of the conditions of Example 1 which were weighed and pulverized / dispersed by the paint shaker containing 0.3 mmφZrO ₂ beads for 8 hours. Then, a dispersion (Liquid A) according to Example 5 in which Li _0.002 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) were dispersed was prepared.

The particle diameter of the Li _0.002 Cs _0.33 WO ₃ fine particles in the dispersion (liquid A) prepared in the same manner as in Example 1 was 150 to 200 nm as a result of TEM observation.

  And as in Example 1, when the optical properties of the near-infrared shield according to Example 5 were measured, the solar radiation transmittance was 35.6% and the haze was 1.1% when the visible light transmittance was 70%. there were.

  In addition, ΔVLT after 72 hours in the heat resistance test was 2.10% and ΔST after 72 hours was 1.12%, confirming improvement in heat resistance as compared with Comparative Example 1 described below. In Example 5, the wet heat resistance test was not performed.

[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.

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, and the lattice constant ratio c / a was 1.027547.

Further, the particle diameter of the Cs _0.33 WO ₃ fine particles in the dispersion (liquid A) prepared in the same manner as in Example 1 so that the amount of Cs _0.33 WO ₃ fine particles is 8% by weight is the result of TEM observation. 10 to 50 nm.

  And like Example 1, when the optical characteristic of the near-infrared shielding body which concerns on the comparative example 1 was measured, when the visible light transmittance | permeability is 70%, the solar radiation transmittance | permeability is 33.3% and haze is 0.6%. there were.

  In addition, ΔVLT after 72 hours in the heat test is 4.87%, ΔST after 72 hours is 2.75%, and ΔVLT after 72 hours in the heat and humidity test is 5.55%. ΔST after 72 hours was 3.01%, which was confirmed to be inferior in heat resistance as compared with Examples 1 to 5 and inferior in moist heat resistance as compared with Example 1.

[Comparative Example 2]
As in Example 1, except that 0.266 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 _0.20 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 fired powder according to Comparative Example 2 by X-ray diffraction, only the peak attributed to Cs _0.33 WO ₃ was observed. Further, the ratio c / a of the lattice constant is 1.029114 (that is, outside the above-mentioned “1.027300 to 1.029000” range of the present invention), and the lattice constant of the Cs _0.33 WO ₃ fine particles containing no lithium is included. The ratio c / a was larger and it was confirmed that lithium was dissolved.

_{Also, Li 0.20} in Li _{0.20 Cs 0.33} WO ₃ fine particles _{Cs 0.33} WO ₃ terms in dispersion prepared in the same manner as in Example 1 so as to be 8 wt% (A solution) in The particle diameter of the Cs _0.33 WO ₃ fine particles was 10 to 50 nm as a result of TEM observation.

  As in Example 1, when the optical characteristics of the near-infrared shield according to Comparative Example 2 were measured, the solar radiation transmittance was 36.5% and the haze was 0.4% when the visible light transmittance was 70%. .

  In addition, ΔVLT after 72 hours in the above heat test is 9.87%, and ΔST after 72 hours is 10.91%, which is inferior in heat resistance as compared with Examples 1 to 5 and Comparative Example 1. It was confirmed. In Comparative Example 2, the wet heat resistance test was not performed.

[Comparative Example 3]
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 3 were produced.

In addition, as a result of the identification of the crystal phase by X-ray diffraction of the fired powder according to Comparative Example 3, only the peak attributed to Cs _0.33 WO ₃ was observed. The ratio c / a of the lattice constant is 1.029107 (that is, outside the above-mentioned “1.027300 to 1.029000” range of the present invention), and the lattice constant of the Cs _0.33 WO ₃ fine particles not containing lithium is The ratio c / a was larger and it was confirmed that lithium was dissolved.

_{Also, Li 0.10} in Li _{0.10 Cs 0.33} WO ₃ fine particles _{Cs 0.33} WO ₃ terms in dispersion prepared in the same manner as in Example 1 so as to be 8 wt% (A solution) in The particle diameter of the Cs _0.33 WO ₃ fine particles was 10 to 50 nm as a result of TEM observation.

  As in Example 1, when the optical characteristics of the near-infrared shield according to Comparative Example 2 were measured, the solar radiation transmittance was 36.2% and the haze was 0.4% when the visible light transmittance was 70%. .

  In addition, ΔVLT after 72 hours in the heat resistance test was 9.80%, and ΔST after 72 hours was 10.86%, which is inferior in heat resistance as compared with Examples 1 to 5 and Comparative Example 1. It was confirmed. In Comparative Example 3, the wet heat resistance test was not performed.

[Comparative Example 4]
Instead of the methods of Examples 1 to 5 and Comparative Examples 1 to 3 described above, in which composite tungsten oxide B fine particles are produced using Cs _0.33 WO ₃ fine particles (composite tungsten oxide A fine particles) as a starting material, a tungsten compound, M An attempt was made to produce composite tungsten oxide B fine particles using a compound having an element and a compound having an Li element.

That is, an aqueous solution in which 9.75 g of cesium carbonate and 6.70 × 10 ⁻² g of lithium carbonate were dissolved in 30 g of water was added to 45.30 g of tungstic acid, mixed, and stirred at 100 ° C. While removing water, a dry powder was obtained.

Next, while supplying 1.6% H ₂ gas using N ₂ gas as a carrier (that is, in a mixed gas atmosphere of an inert gas and a reducing gas), the dry powder is heated to a temperature of 800 ° C. Li _0.010 Cs _0.33 WO ₃ fine particles (that is, composite tungsten oxide B fine particles) were produced by firing (heat treatment) for 20 minutes under the conditions.

As in Example 1, as a result of identification of the crystal phase by X-ray diffraction of the fired powder, a peak of CsLiWO ₄ was recognized in addition to a peak attributed to Cs _0.33 WO ₃ .

  For this reason, subsequent dispersion / film formation evaluation was not performed due to precipitation of heterogeneous phases.

［評 価］
（１）Ｃｓ_０．３３ＷＯ_３微粒子（複合タングステン酸化物Ａ微粒子）の格子定数の比ｃ／ａよりも大きく、その数値が１．０２９０００以下であるリチウムが固溶した「複合タングステン酸化物Ｂ微粒子」を、近赤外線遮蔽材料微粒子として適用した実施例１〜５に係る近赤外線遮蔽体は、可視光透過率７０％のときの日射透過率が全て３７％未満であり、「耐熱試験」および「耐湿熱試験」における７２時間後のΔＶＬＴやΔＳＴも３．０％未満である。

[Evaluation]
(1) “Compound Tungsten Oxide B” in which lithium having a value larger than the lattice constant ratio c / a of Cs _0.33 WO ₃ fine particles (composite tungsten oxide A fine particles) and having a numerical value of 1.029000 or less was dissolved. The near-infrared shields according to Examples 1 to 5 in which “fine particles” are applied as near-infrared shielding material fine particles have all the solar radiation transmittances of less than 37% when the visible light transmittance is 70%. ΔVLT and ΔST after 72 hours in the “moisture and heat resistance test” are also less than 3.0%.

Therefore, since the near-infrared shield according to Examples 1 to 5 has excellent visible light transmission performance and good near-infrared shielding performance, it can be suitably used in the fields of various buildings and vehicle window materials. It has been confirmed that it has excellent heat and moisture resistance such as visible light transmission performance and near infrared shielding performance.
(2) On the other hand, the near-infrared shielding body according to Comparative Example 1 in which Cs _0.33 WO ₃ fine particles (composite tungsten oxide A fine particles) are applied as near-infrared shielding material fine particles has a solar radiation when the visible light transmittance is 70% Although the transmittance is less than 35%, ΔVLT after 72 hours in the above “heat resistance test” is 4.87% and ΔST is 2.75%, which is inferior in heat resistance as compared with Examples 1-5. Furthermore, ΔVLT after 72 hours in the “moisture and heat resistance test” is 5.55% and ΔST is 3.01%, which is inferior to the heat and moisture resistance as compared with Example 1. Visible light transmission performance and near-infrared shielding It is confirmed that there is a problem with the heat and moisture resistance of the performance.
(3) The composition ratio x of Li element is 0.20 and 0.10, which is outside the above-mentioned “0.0001 ≦ x <0.1” range, and Cs _0.33 WO ₃ fine particles ( Li _0.20 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) and Li which are larger than the lattice constant ratio c / a of the composite tungsten oxide A fine particles) and whose numerical value exceeds 1.029000 _The near-infrared shields according to Comparative Example 2 and Comparative Example 3 in which _0.10 Cs _0.33 WO ₃ fine particles (composite tungsten oxide B fine particles) are applied as the near-infrared shielding material fine particles have a visible light transmittance of 70%. The solar transmittance of 36% exceeds 36.5% and 36.2% respectively, and the near-infrared shielding performance is inferior to the near-infrared shielding bodies according to Examples 1 to 5 and Comparative Example 1. Near infrared shielding It was confirmed that there was a problem in performance, and for ΔVLT after 72 hours in the “heat resistance test”, 9.87%, 9.80%, ΔST were 10.91%, 10.86%, It is inferior to Examples 1-5 and the comparative example 1, and it is confirmed that there is a problem in heat resistance / humidity heat resistance of visible light transmission performance and near infrared shielding performance.
(4) In addition, when producing composite tungsten oxide B fine particles in which lithium is dissolved, tungsten compound (tungstic acid) is used without using Cs _0.33 WO ₃ fine particles (composite tungsten oxide A fine particles) as a starting material. In Comparative Example 4 using the compound containing M element (cesium carbonate) and the compound containing Li element (lithium carbonate), it was confirmed that a heterogeneous phase of CsLiWO ₄ was generated and could not be used as near-infrared shielding material fine particles. It was.

  The near-infrared shielding material fine particles according to the present invention have excellent visible light transmission performance and good near-infrared shielding performance, and are also excellent in heat resistance and moisture heat resistance. The present invention has industrial applicability to be used as a constituent material of a near-infrared shield widely used in Japan.

1 WO ₆ units 2 Element (M)

Claims (9)

In the near-infrared shielding material fine particles 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, 0.0001 ≦ x <0.1, 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 The lattice constant ratio c / a is represented by the 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) is larger than the lattice constant ratio c / a of the composite tungsten oxide A, and the numerical value is Near-infrared shielding characterized by being 1.027300 to 1.029000 Fee fine.   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) and a mixture of a compound having a lithium element and a compound having a lithium element is calcined in the atmosphere or in an inert gas atmosphere, and then reduced gas. The near-infrared shielding material fine particles according to claim 1, wherein the fine particles are obtained by heat treatment in an atmosphere or a mixed atmosphere of a reducing gas and an inert gas.   The near-infrared shielding material fine particles according to claim 2, wherein the compound having a lithium element is lithium carbonate. In the manufacturing method of near-infrared shielding material fine particles having absorption in the near-infrared region,
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, and the general formula LixMyWOz (where Li is lithium, M is Cs, Rb, K, Na, One or more elements selected from Ba, Ca, Sr, and Mg, W is tungsten, O is oxygen, 0.0001 ≦ x <0.1, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) A compound having lithium element is added to the raw material so as to have a composition represented by ≦ z ≦ 3.0), and the mixture is fired in the atmosphere or in an inert gas atmosphere, and then in a reducing gas atmosphere. Or heat treatment in a mixed atmosphere of reducing gas and inert gas, The method of producing the near-infrared shielding material fine particles, characterized in that to produce the near infrared ray shielding material fine particles according to claim 1.   The method for producing fine particles of near-infrared shielding material according to claim 4, wherein the compound having a lithium element is lithium carbonate. 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 the general formula LixMyWOz (where Li is lithium, M is one or more elements selected from Cs, Rb, K, Na, Ba, Ca, Sr, and Mg, and W is tungsten. , O is oxygen, 0.0001 ≦ x <0.1, 0.1 ≦ y ≦ 0.5, 2.2 ≦ z ≦ 3.0) and a hexagonal crystal structure in which lithium is dissolved. It is composed of fine particles of composite tungsten oxide B having a lattice constant ratio c / a selected from the general formula MyWOz (where M is selected from 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) Ratio of lattice constant of composite tungsten oxide A c / larger than a and the numerical value is 1.027300 to 1.029000 And near-infrared shielding material microparticle dispersion characterized in that the particle diameter is 1nm or more 500nm or less.   The near-infrared shielding material fine particle dispersion according to claim 6, wherein the medium in which the near-infrared shielding material fine particles are dispersed 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, acrylic resin, The near-infrared shielding material fine particle dispersion according to claim 7, which is at least one selected from polyvinyl butyral resins.   The near-infrared shielding material, wherein the near-infrared shielding material fine particle dispersion according to any one of claims 6 to 8 is formed into a plate shape, a film shape, or a thin film shape.

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