Near-infrared absorbing material particles, near-infrared absorbing material particle dispersion, near-infrared absorbing material particle dispersion

Abstract

Provided are near-infrared absorbing material particles containing particles of a composite tungsten oxide represented by the general formula MxWyOz (where the M element is one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I; W is tungsten; O is oxygen; 0.001≤x / y≤1; and 3.0<z / y).

Description

[Technical Field]

[0001] The present invention relates to near-infrared absorbing material particles, a near-infrared absorbing material particle dispersion, and a near-infrared absorbing material particle dispersion. [Background technology]

[0002] Near-infrared rays contained in sunlight penetrate window materials and other materials, enter indoor spaces, and raise the surface temperatures of the walls and floors inside the room, thereby raising the indoor air temperature. To maintain a comfortable indoor thermal environment, it has been common practice to use light-blocking materials in window materials and other materials to block the near-infrared rays that enter through windows, thereby preventing the indoor air temperature from rising.

[0003] Patent Document 1 proposes a light-shielding film containing black fine powder including inorganic pigments such as carbon black and titanium black, and organic pigments such as aniline black, as a light-shielding material used in window materials and the like.

[0004] Patent Document 2 discloses a thermal insulation sheet made of a woven fabric in which a strip-shaped film having infrared reflectivity and a strip-shaped film having infrared absorbency are used as warp and weft, respectively. It also describes that the strip-shaped film having infrared reflectivity is made by depositing aluminum on a synthetic resin film and laminating another synthetic resin film on top of it.

[0005] The present applicant has proposed in Patent Document 3 an infrared-shielding material microparticle dispersion in which infrared material microparticles are dispersed in a medium, the infrared material microparticles containing tungsten oxide microparticles and / or composite tungsten oxide microparticles, and the dispersed particle diameter of the infrared material microparticles being 1 nm or more and 800 nm or less. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2003-029314 [Patent Document 2] Japanese Patent Publication No. 9-107815 [Patent Document 3] International Publication No. 2005 / 037932 Summary of the Invention [Problem to be solved by the invention]

[0007] However, according to the investigations of the present inventors, it has become clear that the proposals and disclosures described in Patent Document 1 and Patent Document 2 have the following problems.

[0008] The black fine powder described in Patent Document 1 has a large absorption in the visible light region. For this reason, window materials and the like to which this black fine powder is applied have a dark color tone, which is thought to limit the methods and uses of the material.

[0009] Window materials and the like to which a metal vapor deposition film is applied, such as the heat-retaining sheet described in Patent Document 2, have a half-mirror appearance. For this reason, when window materials and the like to which a metal vapor deposition film is applied are used outdoors, the reflection is dazzling and it has been thought that this would cause problems in terms of the scenery.

[0010] Patent Document 3 was made to solve the above-mentioned problems. It provides near-infrared shielding material microparticles, a near-infrared shielding material microparticle dispersion, a near-infrared shielding body, and near-infrared shielding material microparticles, which sufficiently transmit visible light, do not have a half-mirror appearance, efficiently shield invisible near-infrared rays with wavelengths of 780 nm or more, and are transparent and do not change color, as well as a method for producing the same. However, in recent years, performance such as weather resistance has also been required.

[0011] An object of one aspect of the present invention is to provide near-infrared absorbing material particles that are excellent in weather resistance. [Means for solving the problem]

[0012] In one aspect of the invention, compounds of general formula M x W yO z (However, the M element is C s、 R b or and contains particles of a composite tungsten oxide represented by one or more selected elements, W is tungsten, O is oxygen, 0.20 ≦ x / y ≦ 0.37, 3.0 < z / y < 3.4), The composite tungsten oxide has a hexagonal crystal structure, The lattice constant of the composite tungsten oxide is such that the a-axis is 7.3850 Å or more and 7.4186 Å or less, and the c-axis is 7.5600 Å or more and 7.6240 Å or less, providing near-infrared absorbing material particles having a particle size of 10 nm or more and 100 nm or less.

Advantages of the Invention

[0013] In one aspect of the present invention, near-infrared absorbing material particles excellent in weather resistance can be provided.

Brief Description of the Drawings

[0014] [Figure 1] Explanatory drawing of the hybrid plasma reactor used in Example 1. [Figure 2] Explanatory drawing of the high-frequency plasma reactor used in Example 2.

Modes for Carrying Out the Invention

[0015] Hereinafter, the near-infrared absorbing material particles, the near-infrared absorbing material particle dispersion liquid, and the near-infrared absorbing material particle dispersion body according to the present embodiment will be described in detail in the order of "1. Near-infrared absorbing material particles", "2. Method for producing near-infrared absorbing material particles", "3. Near-infrared absorbing material particle dispersion liquid", and "4. Near-infrared absorbing material particle dispersion body". 1. Near-infrared absorbing material particles The near-infrared absorbing material particles according to the present embodiment can contain particles of a composite tungsten oxide represented by the general formula M x W y O z .

[0016] In the general formula above, the M element is one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I. W is tungsten and O is oxygen. x, y, and z can satisfy 0.001 ≦ x / y ≦ 1 and 3.0 < z / y.

[0017] In order to obtain near-infrared absorbing material particles with excellent weather resistance, the inventors of the present invention conducted intensive research. In this specification, "excellent weather resistance" means that the near-infrared absorption characteristics do not change significantly even when placed in a high-temperature environment.

[0018] Generally, it is known that a material containing free electrons exhibits a reflection absorption response due to plasma vibration with respect to electromagnetic waves having wavelengths from 200 nm to 2600 nm around the region of sunlight. And when the powder of the material containing the free electrons is made into particles smaller than the wavelength of light, it is known that the geometric scattering in the visible light region (wavelength of 380 nm or more and 780 nm or less) is reduced and transparency in the visible light region is obtained. In this specification, "transparency" is used to mean less scattering and high transmittance with respect to light in the visible light region.

[0019] Tungsten oxide represented by the general formula WO 3-a and so-called tungsten bronzes obtained by adding a positive element such as Na to tungsten trioxide are known to be conductive materials and materials containing free electrons. And the response of free electrons to light in the near-infrared region has been suggested by the analysis of these materials such as single crystals.

[0020] Generally, since there are no effective free electrons in tungsten trioxide (WO3), it has little absorption and reflection characteristics in the near-infrared region and is not effective as a near-infrared absorption material. Here, it is known that by reducing the ratio of oxygen to tungsten in tungsten trioxide below 3, free electrons are generated in the tungsten oxide.

[0021] Also, conventionally, an M element has been added to the tungsten oxide to form a composite tungsten oxide. This configuration generates free electrons in the composite tungsten oxide, and absorption characteristics derived from the free electrons are exhibited in the near-infrared region, making it effective as a near-infrared absorption material around a wavelength of 1000 nm.

[0022] The inventors of the present invention conducted further research on tungsten oxide and composite tungsten oxide in order to obtain near-infrared absorption material particles with excellent weather resistance. As a result, in near-infrared absorption material particles containing particles of a composite tungsten oxide represented by the general formula M x W y O z it was found that by setting 3.0 < z / y with respect to y and z in the above general formula, both near-infrared absorption characteristics and weather resistance can be achieved, and the present invention was completed.

[0023] The near-infrared absorption material particles of the present embodiment can contain particles of a composite tungsten oxide represented by the general formula M as described above. The near-infrared absorption material particles of the present embodiment can also be composed of particles of a composite tungsten oxide represented by the above general formula. However, even in this case, it does not exclude containing inevitable components mixed in during the manufacturing process or the like.

[0024] ​​​​​​Here, as described above, from the viewpoint of enhancing stability, the M element in the above general formula is preferably one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I. In particular, from the viewpoint of particularly improving the optical properties and weather resistance as a near-infrared absorbing material, the M element is more preferably an alkali metal, alkaline earth metal element, transition metal element, Group 4B element, or Group 5B element.

[0025] When composite tungsten oxide particles contain crystals having a hexagonal crystal structure, the particles have particularly improved transmittance in the visible light region and particularly improved absorption in the near-infrared region. The hexagonal crystal structure is formed by a group of six octahedra formed by WO6 units, which form hexagonal voids (tunnels), and each void is filled with an M element to form a single unit, and these single units are then aggregated together.

[0026] It should be noted that the composite tungsten oxide particles are not limited to those containing crystals having a hexagonal crystal structure, and for example, if they have a structure in which six octahedra formed from the above-mentioned unit structure, i.e., WO6 units, are assembled to form hexagonal voids, and the M element is arranged in the voids, it is possible to particularly improve the transmittance in the visible light region and particularly improve the absorption in the near-infrared region. Therefore, even if the composite tungsten oxide particles do not contain crystals having a hexagonal crystal structure and only have the above-mentioned unit structure, they can still achieve a high effect.

[0027] As described above, when composite tungsten oxide particles have a structure in which cations of the M element are added to hexagonal voids, absorption in the near-infrared region is particularly improved. Generally, adding an M element with a large ionic radius tends to form a hexagonal crystal or the above structure. Specifically, when the composite tungsten oxide contains one or more elements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn as the M element, the hexagonal crystal or the above structure is likely to form. Therefore, the composite tungsten oxide particles preferably contain one or more elements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn as the M element, and more preferably, the M element is one or more elements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn.

[0028] Furthermore, among these M elements having a large ionic radius, particles of a composite tungsten oxide containing one or more elements selected from Cs and Rb are likely to form hexagonal crystals or the above-mentioned structure, and can achieve both absorption in the near-infrared region and transmission in the visible light region, while also exhibiting particularly high performance.

[0029] When particles of a composite tungsten oxide having a hexagonal crystal structure have a uniform crystal structure, x / y, which indicates the content ratio of element M relative to 1 mole of tungsten, is preferably 0.2 or more and 0.5 or less, and more preferably 0.33. When the value of x / y is 0.33, it is believed that element M is arranged in all of the hexagonal voids.

[0030] The composite tungsten oxide particles are also effective as a near-infrared absorbing material when they contain crystals other than the above-mentioned hexagonal crystals, such as tetragonal crystals or cubic crystals.

[0031] The cubic and tetragonal composite tungsten oxides each have a suitable range and upper limit of the amount of element M added, which is derived from their structures, and the upper limit of x / y, which is the content ratio of M element to 1 mole of tungsten, is 1 mole in the case of a cubic crystal, and about 0.5 moles in the case of a tetragonal crystal. Note that the upper limit of x / y, which is the content ratio of M element to 1 mole of tungsten, varies depending on the type of M element, etc., but in the case of a tetragonal crystal, about 0.5 moles is easy to industrially produce.

[0032] However, it is difficult to simply define these structures, and the ranges are examples showing particularly basic ranges, so the present invention is not limited to these.

[0033] Depending on the crystal structure contained in the composite tungsten oxide particles, the absorption position in the near-infrared region tends to change. The absorption position in the near-infrared region tends to shift toward longer wavelengths in tetragonal crystals compared to cubic crystals, and furthermore, the absorption position in the hexagonal crystals tends to shift toward longer wavelengths compared to tetragonal crystals. Furthermore, accompanying this shift in absorption position, absorption in the visible light region is lowest in hexagonal crystals, followed by tetragonal crystals, with cubic crystals having the highest absorption. Therefore, it is preferable to select the crystal system contained depending on the required performance, etc. For example, when used in applications requiring greater transmission of light in the visible light region and greater absorption of light in the near-infrared region, it is preferable that the composite tungsten oxide particles contain hexagonal crystals. However, the trends in the optical properties described here are merely rough trends, and will vary depending on the type and amount of added element and the amount of oxygen, and the present invention is not limited thereto.

[0034] By combining the above-mentioned control of the oxygen content with the addition of an element M that generates free electrons to the composite tungsten oxide, a near-infrared absorbing material with better weather resistance can be obtained. The general formula of the composite tungsten oxide, which is a near-infrared absorbing material that combines the control of the oxygen content and the addition of an element M that generates free electrons, is x W y O zWhen described as such, x and y can satisfy 0.001 ≦ x / y ≦ 1, and preferably satisfy 0.20 ≦ x / y ≦ 0.37.

[0035] Also, for y and z in the above general formula, the relationship 3.0 < z / y is satisfied, preferably 3.0 < z / y < 3.4 is satisfied, more preferably 3.0 < z / y < 3.3 is satisfied, and even more preferably 3.0 < z / y < 3.22 is satisfied.

[0036] The applicant of the present application discloses in Patent Document 1 that for composite tungsten oxide fine particles having a hexagonal crystal structure, when z / y = 3, the value of x / y becomes 0.33, and it is considered that element M is arranged in all of the hexagonal voids.

[0037] It has been confirmed by chemical analysis that the composite tungsten oxide particles contained in the near-infrared absorbing material particles according to the present embodiment have z / y exceeding 3. On the other hand, it has been confirmed by powder X-ray diffraction that the composite tungsten oxide particles contained in the near-infrared absorbing material particles according to the present embodiment may take a tungsten bronze structure of at least one of tetragonal, cubic, and hexagonal when z / y = 3. Therefore, it is preferable that the composite tungsten oxide particles contained in the near-infrared absorbing material particles according to the present embodiment contain crystals of one or more crystal structures selected from hexagonal, tetragonal, and cubic crystals. By containing crystals of the above crystal structure, particularly excellent near-infrared absorption characteristics and visible light transmittance characteristics can be exhibited.

[0038] By the way, it is considered that oxygen atoms when the z / y value exceeds 3 enter the crystal of the composite tungsten oxide particles. As a result, when oxygen atoms enter the crystal, it is considered that excellent weather resistance can be realized without the crystal of the composite tungsten oxide particles being deteriorated even when exposed to heat or moisture.

[0039] The crystal structure of the composite tungsten oxide particles contained in the near-infrared absorbing material particles according to the present embodiment can be confirmed by an X-ray diffraction pattern by the powder X-ray diffraction method (θ-2θ method).

[0040] The near-infrared absorbing material particles of this embodiment exhibit light transmission characteristics having a maximum value in a wavelength range of 350 nm or more and 600 nm or less and a minimum value in a wavelength range of 800 nm or more and 2100 nm or less, and can exhibit excellent near-infrared absorbing effect and weather resistance. The near-infrared absorbing material particles of this embodiment more preferably have a maximum value in a wavelength range of 440 nm or more and 600 nm or less and a minimum value in a wavelength range of 1150 nm or more and 2100 nm or less.

[0041] Furthermore, the near-infrared absorbing material particles according to this embodiment preferably have a particle diameter of 100 nm or less. From the viewpoint of exhibiting better near-infrared absorbing properties, the particle diameter is more preferably 10 nm or more and 100 nm or less, even more preferably 10 nm or more and 80 nm or less, particularly preferably 10 nm or more and 60 nm or less, and most preferably 10 nm or more and 40 nm or less. When the particle diameter of the near-infrared absorbing material particles is in the range of 10 nm or more and 40 nm or less, the best near-infrared absorbing properties are exhibited.

[0042] Here, the particle size refers to the size of each individual near-infrared absorbing material particle that is not aggregated, that is, the particle size of each individual particle.

[0043] The particle size here does not include the size of aggregates of near-infrared absorbing material particles, and is different from the dispersed particle size.

[0044] The particle diameter here can be calculated by, for example, measuring the particle diameters of multiple particles using a transmission electron microscope (TEM) or the like while the near-infrared absorbing material particles are dispersed. Note that since near-infrared absorbing material particles are usually irregular in shape, the diameter of the smallest circle circumscribing the particle can be used as the particle diameter of the particle. For example, when the particle diameters of multiple particles are measured particle by particle using a transmission electron microscope as described above, it is preferable that the particle diameters of all particles satisfy the above range. The number of particles to be measured is not particularly limited, but is preferably, for example, 10 to 50.

[0045] Furthermore, from the viewpoint of exhibiting excellent near-infrared absorption properties, the crystallite diameter of the composite tungsten oxide particles is preferably 10 nm or more and 100 nm or less, more preferably 10 nm or more and 80 nm or less, even more preferably 10 nm or more and 60 nm or less, and particularly preferably 10 nm or more and 40 nm or less. This is because, if the crystallite diameter is in the range of 10 nm or more and 40 nm or less, particularly excellent near-infrared absorption properties are exhibited. The crystallite diameter of the composite tungsten oxide particles contained in the near-infrared absorbing material particles can be calculated using the Rietveld method from the X-ray diffraction pattern measured by powder X-ray diffraction (θ-2θ method).

[0046] The general formula of the composite tungsten oxide contained in the composite tungsten oxide particles is M x W y O z When the M element contains one or more elements selected from Cs and Rb and the composite tungsten oxide has a hexagonal crystal structure, the lattice constant of the composite tungsten oxide is preferably 7.3850 Å or more and 7.4186 Å or less for the a-axis and 7.5600 Å or more and 7.6240 Å or less for the c-axis. By setting the above lattice constants for the composite tungsten oxide, particularly excellent properties can be achieved in terms of near-infrared absorption characteristics and weather resistance. In the above case, it is more preferable that the M element consists of one or more elements selected from Cs and Rb. The above lattice constant can be calculated using the Rietveld method.

[0047] Furthermore, near-infrared absorbing material particle dispersions containing particles of the composite tungsten oxide according to this embodiment largely absorb light in the near-infrared region, particularly light with a wavelength around 1000 nm, and therefore the transmitted color tone is often blue to green.

[0048] The dispersed particle diameter of the near-infrared absorbing material particles of this embodiment can be selected depending on the intended use. First, when used in an application that requires maintaining transparency, it is preferable that the dispersed particle diameter is 800 nm or less. This is because particles with a dispersed particle diameter of 800 nm or less do not completely block light due to scattering, and can maintain visibility in the visible light region while efficiently maintaining transparency.

[0049] In particular, when transparency in the visible light region is important, it is preferable to further consider scattering by particles. Note that the dispersed particle size includes the size of an aggregate of near-infrared absorbing material particles, and is different from the particle size described above.

[0050] When prioritizing the reduction of scattering by the particles, the dispersed particle diameter of the near-infrared absorbing material particles of this embodiment is preferably 200 nm or less, more preferably 10 nm to 200 nm, and even more preferably 10 nm to 100 nm. This is because a small dispersed particle diameter reduces scattering of light in the visible light region with wavelengths of 380 nm to 780 nm due to geometric scattering or Mie scattering, thereby preventing a dispersion containing the near-infrared absorbing material particles of this embodiment from becoming like frosted glass and losing clear transparency. That is, when the dispersed particle diameter is 200 nm or less, the geometric scattering or Mie scattering is reduced, resulting in a Rayleigh scattering region. In the Rayleigh scattering region, scattered light is proportional to the sixth power of the dispersed particle diameter, so scattering is reduced as the dispersed particle diameter decreases, improving transparency. Furthermore, a dispersed particle diameter of 100 nm or less is preferable because scattered light is significantly reduced. From the perspective of avoiding light scattering, a small dispersed particle diameter is preferable, and a dispersed particle diameter of 10 nm or more facilitates industrial production.

[0051] By setting the dispersed particle diameter to 800 nm or less, the haze (haze value) of the near-infrared absorbing material particle dispersion in which near-infrared absorbing material particles are dispersed in a medium can be set to 10% or less at a visible light transmittance of 85% or less. In particular, by setting the dispersed particle diameter to 100 nm or less, the haze can be set to 1% or less.

[0052] The light scattering of the near-infrared absorbing material particle dispersion must be considered in terms of the dispersion particle diameter, since it is necessary to take into account the aggregation of the near-infrared absorbing material particles.

[0053] The surface of the near-infrared absorbing particle of this embodiment may be coated with a compound containing one or more elements selected from Si, Ti, Zr, and Al. By coating the surface of the near-infrared absorbing particle with the compound, weather resistance can be particularly improved.

[0054] The compound containing one or more elements selected from Si, Ti, Zr, and Al can be one or more selected from the group consisting of hydrolysis products of metal chelate compounds containing Si, Ti, Zr, and Al, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds. The metal chelate compounds and metal cyclic oligomer compounds are preferably metal alkoxides, metal acetylacetonates, and metal carboxylates, and therefore preferably have one or more groups selected from ether bonds, ester bonds, alkoxy groups, and acetyl groups.

[0055] The operation of coating the surfaces of the near-infrared absorbing material particles with these compounds is preferably carried out before preparing a near-infrared absorbing material particle dispersion or the like. (1) Surface treatment agents, coating film materials, etc. Here, the surface treatment agent for the near-infrared absorbing material particles of this embodiment, the material for the coating film, etc. will be described in the following order: (1-1) metal chelate compound, (1-2) metal cyclic oligomer compound, (1-3) hydrolysis products of metal chelate compounds and metal cyclic oligomer compounds, and polymers thereof, and (1-4) the amount of surface treatment agent added and the film thickness. (1-1) Metal chelate compounds The metal chelate compound is preferably one or more selected from alkoxy group-containing Si-, Ti-, Zr- and Al-based chelate compounds.

[0056] As the Si-based chelate compound, a tetrafunctional silane compound represented by the general formula Si(OR)4 (where R is the same or different monovalent hydrocarbon group having from 1 to 6 carbon atoms) or a hydrolysis product thereof can be used. Specific examples of tetrafunctional silane compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. As the Si-based chelate compound, it is also possible to use a silane monomer in which some or all of the alkoxy groups of the above-mentioned alkoxysilane monomer have been hydrolyzed to form silanol groups (Si-OH), an oligomer, or a polymer self-condensed through a hydrolysis reaction.

[0057] Furthermore, examples of hydrolysis products of tetrafunctional silane compounds include silane monomers in which some or all of the alkoxy groups have been hydrolyzed to form silanol (Si-OH) groups, oligomers of tetramer to pentamer, and polymers (silicone resins) with a weight-average molecular weight (Mw) of approximately 800 to 8,000. The hydrolysis product of the tetrafunctional silane compound refers to the entire hydrolysis product of the tetrafunctional silane compound. Note that it is not necessary for all of the alkoxysilyl groups (Si-OR) in the alkoxysilane monomer to be hydrolyzed to form silanol (Si-OH) groups during the hydrolysis reaction.

[0058] Examples of Ti-based chelate compounds include titanium alcoholates such as methyl titanate, ethyl titanate, isopropyl titanate, butyl titanate, and 2-ethylhexyl titanate, and polymers thereof, titanium acetylacetonate, titanium tetraacetylacetonate, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate, and titanium triethanolamine.

[0059] Examples of Zr-based chelate compounds include zirconium alcoholates such as zirconium ethylate and zirconium butyrate, or polymers thereof, zirconium tributoxystearate, zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, zirconium dibutoxybis(acetylacetonate), zirconium tributoxyethylacetoacetate, and zirconium butoxyacetylacetonate bis(ethylacetoacetate).

[0060] Examples of Al-based chelate compounds include aluminum alcoholates such as aluminum ethylate, aluminum isopropylate, aluminum sec-butylate, and mono-sec-butoxyaluminum diisopropylate, or polymers thereof, ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl acetoacetate), octyl acetoacetate aluminum diisopropylate, stearyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetonate bis(ethyl acetoacetate), aluminum tris(acetylacetonate), and aluminum ethyl acetoacetate diisopropylate.

[0061] These compounds are alkoxy-containing aluminum chelate compounds obtained by dissolving aluminum alcoholate in an aprotic solvent, petroleum solvent, hydrocarbon solvent, ester solvent, ketone solvent, ether solvent, amide solvent, or the like, adding β-diketone, β-ketoester, monohydric or polyhydric alcohol, fatty acid, or the like to the solution, heating under reflux, and subjecting the solution to a ligand substitution reaction. (1-2) Metallocyclic Oligomer Compounds The metal cyclic oligomer compound is preferably one or more selected from Al-, Zr-, Ti-, and Si-based cyclic oligomer compounds, such as cyclic aluminum oxide octylate, cyclic aluminum oxide isopropylate, and cyclic aluminum oxide stearate. (1-3) Hydrolysis products of metal chelate compounds and metallocyclic oligomer compounds, and their polymers The hydrolysis products of the metal chelate compounds and metal cyclic oligomer compounds, and polymers thereof, may be one or more selected from hydrolysis products in which all of the alkoxy groups, ether bonds, and ester bonds in the above-mentioned metal chelate compounds and metal cyclic oligomer compounds have been hydrolyzed to form hydroxyl groups or carboxyl groups, partial hydrolysis products in which only a portion of the alkoxy groups, ether bonds, and ester bonds have been hydrolyzed, and polymers self-condensed through the hydrolysis reaction.

[0062] The near-infrared absorbing material particles of this embodiment can be obtained by coating the surfaces of the near-infrared absorbing material particles with one or more types selected from the hydrolysis products and polymers described above to form a coating film.

[0063] That is, the above hydrolysis product is not limited to a hydrolysis product in which all of the alkoxy groups and the like have been hydrolyzed, but includes a partial hydrolysis product.

[0064] In this specification, "a coating film formed on the surface of a near-infrared absorbing material particle using one or more selected from a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound" may be simply referred to as "a coating film".

[0065] For example, in a reaction system involving an organic solvent such as alcohol, even if sufficient water is present in the system based on the stoichiometric composition, not all of the alkoxy groups, ether bonds, and ester bonds of the metal chelate compound or metal cyclic oligomer compound used as the starting material are hydrolyzed depending on the type and concentration of the organic solvent. Therefore, depending on the conditions of the surface coating method described below, even after hydrolysis, the hydrolysis product may become amorphous, with carbon C incorporated into the molecule. As a result, the coating film may contain one or more undecomposed metal chelate compounds and metal cyclic oligomer compounds, but this is not a particular problem as long as the amount is so small that it does not cause aggregation of near-infrared absorbing material particles.

[0066] When the coating film contains one or more undecomposed metal chelate compounds and cyclic metal oligomer compounds, the hydrolysis and dehydration condensation reactions of silane coupling agents, silane alkoxides, and polysilazanes in the dispersion (coating liquid) used to prepare a near-infrared absorbing material dispersion in a subsequent process may rapidly proceed. Furthermore, as a result of the rapid progression of these reactions, the polymers of the silane coupling agents, silane alkoxides, and polysilazanes may act as crosslinkers, causing aggregation of near-infrared absorbing material particles in the near-infrared absorbing material particle dispersion used for surface treatment. Aggregation of near-infrared absorbing material particles may also result in a decrease in properties such as visible light transparency.

[0067] To avoid such a situation, when the coating film contains undecomposed metal chelate compounds or cyclic metal oligomer compounds, it is preferable to proceed with the decomposition of these compounds in the "(2-5) heat treatment step" described below, and allow them to react until they become polymerized reactive hydrolysis products.

[0068] That is, in the coating film that coats the surface of the near-infrared absorbing material particle, it is preferable that the alkoxy groups, ether bonds, and ester bonds contained in the metal chelate compound or the cyclic metal oligomer compound are partially or entirely hydrolyzed, and the hydrolysis products that have become hydroxyl groups or carboxyl groups are preferably polymers that have self-condensed through the hydrolysis reaction. (1-4) Amount of surface treatment agent added, film thickness The amount of the metal chelate compound or metal cyclic oligomer compound added when forming the coating film is not particularly limited, but is preferably 0.05 parts by mass or more and 1,000 parts by mass or less, more preferably 5 parts by mass or more and 500 parts by mass or less, and even more preferably 50 parts by mass or more and 250 parts by mass or less, in terms of metal element, relative to 100 parts by mass of the near-infrared absorbing material particles.

[0069] This is because, when the amount of the metal chelate compound or the metal cyclic oligomer compound added is 0.05 parts by mass or more in terms of metal element, the hydrolysis product of the compound or the polymer of the hydrolysis product has the effect of coating the surface of the near-infrared absorbing material particles, that is, a particularly high effect in improving weather resistance is obtained.

[0070] Furthermore, when the amount of the metal chelate compound or the metal cyclic oligomer compound added is 1,000 parts by mass or less in terms of metal element, it is possible to avoid excessive adsorption onto the near-infrared absorbing material particles, and the improvement in weather resistance due to the surface coating does not saturate, and an improvement in the coating effect can be expected.

[0071] By setting the amount of metal chelate compound or metal cyclic oligomer compound to 1,000 parts by mass or less in terms of metal element, excessive adsorption onto near-infrared absorbing material particles can be avoided. This prevents near-infrared absorbing material particles from easily granulating together via hydrolysis products of the metal chelate compound or metal cyclic oligomer compound or polymers of the hydrolysis products when removing the medium after forming a coating film. Suppressing granulation between near-infrared absorbing material particles ensures good transparency. Additionally, increased production costs due to increased addition amounts and processing times caused by excess metal chelate compound or metal cyclic oligomer compound can be avoided. Therefore, from an industrial perspective, it is preferable to set the amount of metal chelate compound or metal cyclic oligomer compound to 1,000 parts by mass or less in terms of metal element.

[0072] The thickness of the coating film of the near-infrared absorbing material particles is not particularly limited, but is preferably 0.5 nm or more. This is because if the coating film is 0.5 nm or more, the near-infrared absorbing material particles are thought to exhibit particularly excellent weather resistance and chemical stability. On the other hand, from the viewpoint of fully ensuring the optical properties of the near-infrared absorbing material particles, it is thought that the thickness of the coating film is preferably 100 nm or less. The thickness of the coating film is more preferably 0.5 nm or more and 20 nm or less, and even more preferably 1 nm or more and 10 nm or less.

[0073] The thickness of the coating film can be measured from a transmission electron microscope image of the surface-treated infrared absorbing material particles. (2) Method for producing surface-coated near-infrared absorbing material particles To produce surface-coated near-infrared absorbing material particles, first, near-infrared absorbing material particles are dispersed in water or a water-containing organic solvent to prepare a near-infrared absorbing material particle dispersion for forming a coating film (hereinafter, sometimes referred to as "coating film forming dispersion") (coating film forming dispersion preparation step). Note that the surface-coated near-infrared absorbing material particles can be produced by "2. Method for producing near-infrared absorbing material particles" described below.

[0074] The surface treatment agent explained in "(1) Surface treatment agent, coating film material, etc." is prepared (surface treatment agent preparation step).

[0075] Then, while mixing and stirring the dispersion liquid for forming a coating film, a surface treatment agent is added thereto (surface treatment agent addition step).

[0076] After the near-infrared absorbing material particles are surface-coated by the surface treatment agent addition step, the solvent in the mixture of the coating film-forming dispersion, the surface treatment agent, and a solvent such as water can be removed by an appropriate drying treatment (drying step). (2-1) Dispersion preparation process for coating film formation In the step of preparing a dispersion liquid for forming a coating film, the dispersion liquid for forming a coating film is preferably prepared by pulverizing near-infrared absorbing material particles in advance as necessary, dispersing them in water or an appropriate organic solvent containing water, and making them monodisperse. The dispersion concentration of the near-infrared absorbing material particles in the dispersion liquid is preferably 0.01% by mass or more and 80% by mass or less. By setting the dispersion concentration within this range, the liquid stability of the dispersion liquid can be improved.

[0077] In the dispersion liquid prepared in the coating film-forming dispersion liquid preparation step, it is preferable that the near-infrared absorbing material particles are kept dispersed and do not aggregate. This is to prevent the near-infrared absorbing material particles from aggregating and becoming surface-coated in the form of aggregates in the subsequent surface treatment agent addition step for performing surface treatment on the near-infrared absorbing material particles. This is also to prevent the aggregates from remaining in the near-infrared absorbing material particle dispersion described below, thereby reducing the transparency of the near-infrared absorbing material particle dispersion.

[0078] The specific method for pulverizing and dispersing the near-infrared absorbing material particles in the step of preparing the dispersion for forming a coating film is not particularly limited, and examples thereof include pulverizing and dispersing methods using devices such as a bead mill, a ball mill, a sand mill, a paint shaker, an ultrasonic homogenizer, etc. Among these, pulverizing and dispersing using a media such as beads, balls, or Ottawa sand in a media agitation mill such as a bead mill, a ball mill, a sand mill, or a paint shaker is preferred because it takes a short time to reach the desired dispersed particle size. (2-2) Surface treatment agent preparation process In the surface treatment agent preparation step, it is sufficient to prepare the surface treatment agent already described, and therefore a description thereof will be omitted here. (2-3) Surface treatment agent addition process In the surface treatment agent addition step, the surface treatment agent can be added to the coating film-forming dispersion while mixing and stirring the dispersion.

[0079] In the surface treatment agent addition step, the surfaces of the near-infrared absorbing material particles are coated with a coating film containing one or more selected from the group consisting of a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound.

[0080] In the surface treatment agent addition step, the surface treatment agent is added while mixing and stirring the prepared dispersion for forming a coating film. At this time, it is desirable to dilute the dispersion for forming a coating film to an appropriate concentration with water or an appropriate organic solvent containing water, as necessary. Specifically, for example, it is preferable to dilute the dispersion so that the dispersion concentration of the near-infrared absorbing material particles is 0.01% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less. Diluting to the above dispersion concentration ensures more uniform surface coating of all the contained near-infrared absorbing material particles.

[0081] Hereinafter, the addition will be described in the order of (2-3-1) a method for surface coating near-infrared absorbing material particles using a dispersion for forming a coating film containing water as a medium, and (2-3-2) a method for surface coating near-infrared absorbing material particles using a dispersion for forming a coating film containing a water-containing organic solvent as a medium. (2-3-1) Surface coating method for near-infrared absorbing material particles using a dispersion liquid for forming a coating film containing water as a medium The inventors of the present invention have found that, in preparing the above-mentioned dispersion for forming a coating film, it is preferable to add a surface treatment agent to the dispersion for forming a coating film containing water as a medium while stirring and mixing the dispersion, and further to immediately complete the hydrolysis reaction of the added metal chelate compound and metal cyclic oligomer compound. Note that, from the viewpoint of uniformly coating the surface of the near-infrared absorbing material particles, it is preferable to add the surface treatment agent dropwise.

[0082] This is thought to be due to the reaction order of the added surface treatment agent. In a dispersion for forming a coating film using water as a medium, the hydrolysis reaction of the surface treatment agent always occurs first, followed by a polymerization reaction of the generated hydrolysis product. As a result, it is thought that the amount of carbon (C) remaining in the molecules of the surface treatment agent present in the coating film can be reduced compared to when water is not used as a medium. It is thought that by reducing the amount of carbon (C) remaining in the molecules of the surface treatment agent present in the coating film, it is possible to form a coating film that densely coats the surfaces of individual near-infrared absorbing material particles.

[0083] When adding the surface treatment agent dropwise, it is also preferable to add the surface treatment agent itself diluted with an appropriate solvent dropwise in order to adjust the amount of the surface treatment agent added per unit time. The solvent used for dilution is preferably one that does not react with the surface treatment agent and has high compatibility with water, which is the medium of the dispersion for forming a coating film. Specifically, alcohol-based, ketone-based, glycol-based, and other solvents can be preferably used.

[0084] The dilution ratio of the surface treatment agent is not particularly limited, but from the viewpoint of ensuring productivity, the dilution ratio is preferably 100 times or less.

[0085] In the above-mentioned dispersion for forming a coating film containing water as a medium, the metal chelate compound, the metal cyclic oligomer compound, their hydrolysis products, and polymers of the hydrolysis products are decomposed into metal ions immediately after addition, but the decomposition into the metal ions ends when the solution becomes saturated.

[0086] On the other hand, in the coating film-forming dispersion liquid containing water as a medium, the near-infrared absorbing material particles are kept dispersed by electrostatic repulsion.

[0087] As a result, the surfaces of all near-infrared absorbing material particles are coated with a coating film containing one or more selected from the group consisting of hydrolysis products of metal chelate compounds, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds. (2-3-2) Surface coating method for near-infrared absorbing material particles using a dispersion for forming a coating film using an organic solvent containing water As a variation of the surface coating method for near-infrared absorbing material particles using the above-mentioned dispersion liquid for forming a coating film containing water as a medium, a method is also preferred in which an organic solvent containing water is used as a medium for the dispersion liquid for forming a coating film, and the above-mentioned reaction sequence is carried out while adjusting the amount of water to be added to an appropriate value.

[0088] This preparation method is suitable when it is desired to reduce the amount of water contained in the coating film-forming dispersion for convenience of subsequent steps, for example.

[0089] Specifically, the above-mentioned surface treatment agent and pure water are added dropwise in parallel while stirring and mixing a dispersion for forming a coating film containing an organic solvent containing water. At this time, the medium temperature, which affects the reaction rate, and the dropping speed of the surface treatment agent and pure water are appropriately controlled. Note that the organic solvent may be any solvent that dissolves in water at room temperature, such as an alcohol, ketone, or glycol solvent, and various solvents can be selected.

[0090] When adding the surface treatment agent dropwise, it is preferable to add the surface treatment agent diluted with an appropriate solvent in order to adjust the amount of the surface treatment agent added per unit time. In this case, the solvent used for dilution is preferably one that does not react with the surface treatment agent and has high compatibility with the organic solvent containing water that is the medium of the dispersion for forming the coating film. Specifically, alcohol-based, ketone-based, glycol-based, and other solvents can be preferably used.

[0091] The dilution ratio of the surface treatment agent can be the same as in the "(2-3-1) Method for surface coating near-infrared absorbing material particles using a dispersion liquid for forming a coating film containing water as a medium" already explained. (2-4) Drying process In the drying step, after the near-infrared absorbing material particles are surface-coated in the surface treatment agent addition step, the solvent in the mixture of the coating film-forming dispersion, the surface treatment agent, and a solvent such as water can be removed by an appropriate drying treatment.

[0092] As the drying treatment equipment, from the viewpoint of being capable of one or more operations selected from heating and decompression and facilitating mixing and recovery of the surface-coated near-infrared absorbing material particles, an atmospheric dryer, a universal mixer, a ribbon mixer, a vacuum fluidized bed dryer, a vibration fluidized bed dryer, a freeze dryer, a Ribocone, a rotary kiln, a spray dryer, a Pulcon dryer, and the like are preferred, but are not limited to these.

[0093] The drying temperature in the drying step is not particularly limited, but is preferably a temperature higher than that at which the solvent in the dispersion volatilizes and at which the element M does not desorb from the composite tungsten oxide contained in the near-infrared absorbing material particles even in the air. For example, the drying temperature is preferably 150°C or lower. (2-5) Heat treatment process As described above in "(1-3) Hydrolysis products of metal chelate compounds and cyclic metal oligomer compounds, and their polymers," when undecomposed metal chelate compounds or cyclic metal oligomer compounds are contained in the coating film of the surface-treated near-infrared absorbing material particles, it is preferable to promote the decomposition of the chelate compounds, etc. by heat treatment. Therefore, a heat treatment step can be carried out as necessary.

[0094] The conditions for the heat treatment are not particularly limited, and the heat treatment can be carried out in an air atmosphere or an inert gas atmosphere. However, since the heat treatment is preferably carried out so as not to desorb the M element of the composite tungsten oxide contained in the near-infrared absorbing material particles, the heat treatment atmosphere is preferably an inert gas atmosphere.

[0095] The heat treatment temperature is not particularly limited, but is preferably a temperature equal to or higher than the temperature at which the metal chelate compound or metal cyclic oligomer compound contained in the coating film decomposes and lower than the temperature at which the near-infrared absorbing material particles begin to crystallize. Specifically, the heat treatment temperature is preferably in the range of 200°C or higher and lower than 500°C.

[0096] For example, by performing heat treatment within the above temperature range, the decomposition of undecomposed metal chelate compounds and metal cyclic oligomer compounds can be promoted without causing particle growth of the near-infrared absorbing material particles, thereby obtaining surface-treated near-infrared absorbing material particles. 2. Method for producing near-infrared absorbing material particles A configuration example of a method for producing near-infrared absorbing particles will be described. According to the method for producing near-infrared absorbing particles of this embodiment, the near-infrared absorbing particles described above can be produced. Therefore, some of the matters already described will not be described again.

[0097] The near-infrared absorbing material particles of this embodiment contain the above-described general formula M x W y O z The composite tungsten oxide particles represented by the formula (I) can be produced by, for example, the following solid-state reaction method or plasma method.

[0098] Each method will be explained below. (1) Solid-state reaction method When composite tungsten oxide particles are produced by a solid-state reaction method, the following steps may be included.

[0099] A tungsten compound and an M element compound are mixed to prepare a raw material mixture (mixing step). Preferably, the raw material mixture is blended and mixed so that the molar ratio of the M element to tungsten in the raw material mixture is the ratio of x to y in the above general formula of the target composite tungsten oxide particles.

[0100] The raw material mixture obtained in the mixing step is heat-treated in an atmosphere containing oxygen (first heat treatment step).

[0101] The heat-treated product obtained after the first heat treatment step is heat-treated in a reducing gas atmosphere, a mixed gas atmosphere of a reducing gas and an inert gas, or an inert gas atmosphere (second heat treatment step).

[0102] After the second heat treatment step, if necessary, a pulverization treatment or the like may be carried out so that the particles of the near-infrared absorbing material have a desired particle size.

[0103] The near-infrared absorbing material particles of the present embodiment, including the composite tungsten oxide particles obtained by the above steps, have sufficient near-infrared absorbing power and have properties preferred as near-infrared absorbing material particles. In addition, the near-infrared absorbing material particles can be excellent in weather resistance.

[0104] Each step will be described in detail below. (Mixing process) The tungsten compound to be subjected to the mixing step can be one or more compounds selected from the group consisting of tungsten acid (H2WO4), ammonium tungstate, tungsten hexachloride, and tungsten hydrate obtained by adding water to tungsten hexachloride dissolved in alcohol to hydrolyze it, and then evaporating the solvent.

[0105] The M element compound to be subjected to the mixing step may be, for example, one or more selected from oxides, hydroxides, nitrates, sulfates, chlorides, and carbonates of the M element.

[0106] In the mixing step, when mixing the tungsten compound and the M element compound, the mass ratio (M:W) of the M element (M) to tungsten (W) in the resulting raw material mixture is adjusted to satisfy the target general formula M x W y O z It is preferable to mix the raw materials so that x:y is equal to the above.

[0107] The mixing method is not particularly limited, and either wet mixing or dry mixing can be used. In the case of wet mixing, a mixed powder of the M element compound and the tungsten compound is obtained by drying the mixture obtained after wet mixing. The drying temperature and time after wet mixing are not particularly limited.

[0108] The dry mixing may be carried out using a known mixing device such as a commercially available crusher, kneader, ball mill, sand mill, or paint shaker, and there are no particular limitations on the mixing conditions such as the mixing time and mixing speed. (First heat treatment step) The heat treatment temperature in the first heat treatment step is not particularly limited, but is preferably higher than the temperature at which the composite tungsten oxide particles crystallize, specifically, for example, 500°C or higher and 1000°C or lower, and more preferably 500°C or higher and 800°C or lower. (Second heat treatment process) In the second heat treatment step, as described above, heat treatment can be performed in a reducing gas atmosphere, a mixed gas atmosphere of a reducing gas and an inert gas, or an inert gas atmosphere at a temperature of 500°C or higher and 1200°C or lower.

[0109] When a reducing gas is used in the second heat treatment step, the type of reducing gas is not particularly limited, but hydrogen (H2) is preferred. Furthermore, when hydrogen is used as the reducing gas, its concentration is not particularly limited and can be appropriately selected depending on the firing temperature, the amount of the starting materials, etc. For example, it is 20 vol% or less, preferably 10 vol% or less, and more preferably 7 vol% or less. A reducing gas concentration of 20 vol% or less can avoid the formation of WO2, which does not have solar radiation shielding properties, due to rapid reduction. (2) Plasma method The near-infrared absorbing material particles of this embodiment contain the above-described general formula M x W y O z The composite tungsten oxide particles represented by the formula (I) can also be produced by, for example, a plasma method. When producing near-infrared absorbing material particles by a plasma method, the following steps can be included.

[0110] As a starting material, a raw material mixture of a tungsten compound and an M element compound, or a compound represented by the general formula M x W y O z´ A composite tungsten oxide precursor represented by the following formula is prepared (raw material preparation step).

[0111] The starting material prepared in the raw material preparation step is supplied to plasma together with a carrier gas, and undergoes evaporation and condensation processes to produce the desired composite tungsten oxide particles (reaction step). (Raw material preparation process) When preparing a raw material mixture of a tungsten compound and an M element compound as a starting material, it is preferable to blend and mix the raw materials so that the mass ratio (M:W) of the M element (M) to tungsten (W) in the raw material mixture of the tungsten compound and the M element compound is equal to the ratio x:y of x to y in the general formula of the target composite tungsten oxide described above.

[0112] As the tungsten compound and the M element compound, the same materials as those explained in the solid-phase reaction method can be suitably used, and therefore a description thereof will be omitted here.

[0113] Also, in the composite tungsten oxide precursor represented by the general formula M x W y O z´ M can be the aforementioned M element, W can be tungsten, and O can be oxygen. It is preferable that x, y, and z´ satisfy 0.001 ≦ x / y ≦ 1 and 2.0 < z´ / y.

[0114] The general formula M x W y O z´ The composite tungsten oxide precursor represented by can be synthesized, for example, by the aforementioned solid-phase reaction method. It is preferable that x / y in such a composite tungsten oxide precursor is a material that matches x / y in the particles of the composite tungsten oxide represented by the target general formula M x W y O z (Reaction process) As the carrier gas for transporting the starting materials in the reaction process, a mixed gas of an inert gas and an oxygen gas can be used.

[0115] The plasma can be generated, for example, in an atmosphere of an inert gas alone or a mixed gas of an inert gas and a hydrogen gas. The plasma is not particularly limited, but a thermal plasma is preferable. The raw materials supplied into the plasma evaporate instantaneously, and the evaporated raw materials condense in the process of reaching the plasma afterglow part and are rapidly solidified outside the plasma frame to generate particles of the composite tungsten oxide. According to the plasma method, for example, particles of a composite tungsten oxide with a single crystal phase can be generated.

[0116] ​The plasma used in the method for producing near-infrared absorbing material particles of this embodiment is preferably, for example, any one of DC arc plasma, high-frequency plasma, microwave plasma, and low-frequency AC plasma, or a combination of these, or plasma obtained by an electrical method in which a magnetic field is applied to DC plasma, plasma obtained by a high-power laser, or plasma obtained by a high-power electron beam or ion beam. Whichever thermal plasma is used, it is preferably a thermal plasma having a high-temperature portion of 10,000 K or higher, more preferably 10,000 K or higher and 25,000 K or lower, and in particular, plasma in which the particle generation time can be controlled.

[0117] A specific example of the configuration of the reaction step in the method for producing near-infrared absorbing material particles of this embodiment by a plasma method will be described with reference to FIG.

[0118] The device shown in FIG. 1 is a hybrid plasma reactor 10 in which a DC plasma device and a high frequency plasma device are superimposed.

[0119] The hybrid plasma reactor 10 has a water-cooled quartz double tube 11 and a reaction vessel 12 connected to the water-cooled quartz double tube 11. A vacuum exhaust device 13 is connected to the reaction vessel 12.

[0120] A DC plasma torch 14 is provided above the water-cooled quartz double tube 11, and the DC plasma torch 14 is provided with a plasma generation gas supply port 15.

[0121] The system is configured so that sheath gas for generating high-frequency plasma and protecting the quartz tube can be supplied along the inner wall of the water-cooled quartz double tube 11 outside the plasma region, and a sheath gas inlet 16 is provided on the upper flange of the water-cooled quartz double tube 11.

[0122] A water-cooled copper coil 17 for generating high-frequency plasma is arranged around the water-cooled quartz double tube 11 .

[0123] A raw material powder carrier gas supply port 18 is provided near the DC plasma torch 14 and is connected by piping to a raw material powder supply device 19 that supplies raw material powder.

[0124] A gas supply device 20 can be connected by piping to the plasma generation gas supply port 15, the sheath gas inlet 16, and the raw material powder supply device 19, so that a predetermined gas can be supplied to each component from the gas supply device 20. If necessary, supply ports can be provided in addition to the components described above so that the components in the device can be cooled or a predetermined atmosphere can be created, and these can be connected to the gas supply device 20.

[0125] An example of the configuration of a method for producing composite tungsten oxide particles using the hybrid plasma reactor 10 will be described.

[0126] First, the reaction system consisting of the water-cooled quartz double tube 11 and the reaction vessel 12 is evacuated using the vacuum exhaust device 13. The degree of vacuum at this time is not particularly limited, but it can be evacuated to, for example, about 0.1 Pa (about 0.001 Torr). After the reaction system is evacuated, argon gas is supplied from the gas supply device 20, and the reaction system can be filled with argon gas. For example, it is preferable to have an argon gas flow system at 1 atmosphere within the reaction system.

[0127] Thereafter, a plasma gas can be supplied into the reaction vessel 12. The plasma gas is not particularly limited, but can be any gas selected from, for example, argon gas, a mixed gas of argon and helium (Ar-He mixed gas), a mixed gas of argon and nitrogen (Ar-N mixed gas), neon, helium, and xenon.

[0128] The supply flow rate of the plasma gas is not particularly limited, but for example, it can be introduced from the plasma generating gas supply port 15 at a flow rate of preferably 3 L / min to 30 L / min, more preferably 3 L / min to 15 L / min. Then, DC plasma can be generated.

[0129] Meanwhile, outside the plasma region, sheath gas for generating high-frequency plasma and protecting the quartz tube can be supplied in a spiral pattern from sheath gas inlet 16 along the inner wall of water-cooled quartz double tube 11. There are no particular limitations on the type or supply rate of the sheath gas, but for example, argon gas at 20 L / min to 50 L / min and hydrogen gas at 1 L / min to 5 L / min can be flowed to generate high-frequency plasma.

[0130] A high frequency power supply can then be applied to the water-cooled copper coil 17 for generating high frequency plasma. The conditions of the high frequency power supply are not particularly limited, but for example, a high frequency power supply of about 4 MHz and 15 kW to 50 kW can be applied.

[0131] After generating such a hybrid plasma, the raw material can be introduced using a carrier gas from a raw material powder carrier gas supply port 18 by a raw material powder supply device 19. There are no particular limitations on the carrier gas, and for example, a mixed gas consisting of argon gas at 1 L / min to 8 L / min and oxygen gas at 0.001 L / min to 0.8 L / min can be used.

[0132] The starting material mixture or composite tungsten oxide precursor is introduced into the plasma to carry out the reaction. The supply rate of the starting material from the raw material powder carrier gas supply port 18 is not particularly limited, but is preferably 1 g / min to 50 g / min, more preferably 1 g / min to 20 g / min.

[0133] By setting the feed rate of the starting material to 50 g / min or less, the proportion of the starting material passing through the center of the plasma flame can be sufficiently increased, the proportion of unreacted materials and intermediate products can be suppressed, and the proportion of the desired composite tungsten oxide particles produced can be increased. Also, by setting the feed rate of the starting material to 1 g / min or more, productivity can be increased.

[0134] The starting material supplied to the plasma is instantly vaporized in the plasma and undergoes a condensation process to produce composite tungsten oxide particles with an average primary particle size of 100 nm or less.

[0135] The particle size of the composite tungsten oxide particles obtained by the manufacturing method of this embodiment can be easily controlled by the plasma output, plasma flow rate, the amount of raw material powder supplied, and the like.

[0136] After the reaction, the composite tungsten oxide particles produced are deposited in the reaction vessel 12 and can be recovered.

[0137] The near-infrared absorbing material particles obtained by the production method described above may be coated on the surface with a coating film. The method for forming the coating film has already been described, so the description will be omitted here.

[0138] The method for producing near-infrared absorbing particles of the present embodiment has been described above. The near-infrared absorbing particles obtained by this production method can be evaluated and confirmed, for example, by the following method.

[0139] For example, the constituent elements of the near-infrared absorbing material particles obtained by the above-mentioned method for producing near-infrared absorbing material particles can be quantitatively analyzed by chemical analysis. The analytical method is not particularly limited, but for example, the M element and tungsten can be analyzed by plasma emission spectroscopy, and oxygen can be analyzed by inert gas impulse heating fusion infrared absorption spectroscopy.

[0140] The crystal structure of the composite tungsten oxide particles contained in the near-infrared absorbing material particles can be confirmed by powder X-ray diffraction.

[0141] The particle size of the near-infrared absorbing material particles can be confirmed by particle size measurement based on TEM observation or dynamic light scattering. 3. Near-infrared absorbing material particle dispersion The near-infrared absorbing material particle dispersion liquid of this embodiment can contain the near-infrared absorbing material particles described above and a dispersion medium.

[0142] The near-infrared absorbing material particles are preferably dispersed in a dispersion medium.

[0143] The near-infrared absorbing material particle dispersion liquid according to this embodiment is obtained by mixing and dispersing near-infrared absorbing material particles containing the above-described composite tungsten oxide particles in an appropriate dispersion medium (solvent).

[0144] The type of dispersion medium used in the near-infrared absorbing material particle dispersion liquid of this embodiment is not particularly limited. For example, the dispersion medium can be selected depending on the conditions, environment, etc. when the dispersion liquid is applied or kneaded into other materials. Furthermore, when the near-infrared absorbing material particle dispersion liquid of this embodiment further contains other components such as an inorganic binder or a binder such as a resin binder, the dispersion medium can be selected in accordance with the other components, for example, the binder.

[0145] The dispersion medium may be one or more selected from water, alcohols such as ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol, and diacetone alcohol, ethers such as methyl ether, ethyl ether, and propyl ether, esters, ketones such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, isobutyl ketone, and methyl isobutyl ketone, and aromatic hydrocarbons such as toluene, and various organic solvents.

[0146] The dispersion medium may be a resin monomer or oligomer.

[0147] Although the content ratio of the dispersion medium in the near-infrared absorbing material particle dispersion liquid is not particularly limited, it is preferable that the dispersion medium is contained in an amount of 80 parts by mass or more relative to 100 parts by mass of the near-infrared absorbing material particles. This is because, by containing the dispersion medium in an amount of 80 parts by mass or more relative to 100 parts by mass of the near-infrared absorbing material particles, it is easy to ensure the storage stability of the dispersion liquid and also ensure workability when preparing a near-infrared absorbing material particle dispersion.

[0148] The near-infrared absorbing material particle dispersion liquid of this embodiment may contain any optional components in addition to the near-infrared absorbing material particles and the dispersion medium.

[0149] For example, when water is used as the dispersion liquid, the pH of the dispersion liquid may be adjusted by adding an acid or alkali to the near-infrared absorbing material particle dispersion liquid of this embodiment.

[0150] On the other hand, in order to further improve the dispersion stability of the near-infrared absorbing material particles in the dispersion liquid, the near-infrared absorbing material particle dispersion liquid of the present embodiment may further contain various dispersants, surfactants, coupling agents, etc.

[0151] The method for dispersing near-infrared absorbing material particles in a dispersion medium is not particularly limited. For example, it is preferable that the method be a method for uniformly dispersing near-infrared absorbing material particles in a dispersion medium, and that the particle size of the near-infrared absorbing material particles can be adjusted. Specifically, it is preferable that the method be a method for uniformly dispersing near-infrared absorbing material particles in a dispersion medium, and that the particle size of the near-infrared absorbing material particles is 100 nm or less, more preferably a method for 10 nm to 100 nm, even more preferably a method for 10 nm to 80 nm, particularly preferably a method for 10 nm to 60 nm, and most preferably a method for 10 nm to 40 nm. Note that, when the near-infrared absorbing material particles are sufficiently atomized in the near-infrared absorbing material particle dispersion, the crystallite size of the composite tungsten oxide particles contained in the near-infrared absorbing material particles is approximately equal to the particle size of the near-infrared absorbing material particles.

[0152] Examples of a method for dispersing the near-infrared absorbing material particles in a dispersion medium include one or more methods selected from a bead mill, a ball mill, a sand mill, a paint shaker, an ultrasonic homogenizer, and the like.

[0153] By mechanical dispersion treatment using these equipments, the particles of the near-infrared absorbing material are dispersed in the dispersion medium, and at the same time, the particles of the near-infrared absorbing material are atomized due to collisions between each other.

[0154] The state of the near-infrared absorbing material particle dispersion liquid of this embodiment can be confirmed by measuring the dispersion state of the near-infrared absorbing material particles when the near-infrared absorbing material particles are dispersed in a dispersion medium. For example, it can be confirmed by sampling a sample from a liquid in which the near-infrared absorbing material particles of this embodiment exist as particles and particle aggregates in a dispersion medium, and measuring the state using various commercially available particle size distribution meters. As the particle size distribution meter, for example, a known measuring device based on the dynamic light scattering method, such as the ELS-8000 manufactured by Otsuka Electronics Co., Ltd., can be used.

[0155] From the viewpoint of optical properties, the dispersed particle size of the near-infrared absorbing material particles is preferably 800 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less.

[0156] The lower limit of the dispersed particle size of the near-infrared absorbing material is not particularly limited, but is preferably, for example, 10 nm or more.

[0157] The near-infrared absorbing material particles are preferably uniformly dispersed in the dispersion medium.

[0158] By setting the dispersed particle diameter of the near-infrared absorbing material particles to 800 nm or less, it is possible to prevent, for example, a near-infrared absorbing film (near-infrared shielding film) or a molded product (plate, sheet, etc.) produced using the near-infrared absorbing material particle dispersion from becoming grayish in color with monotonically decreasing transmittance.

[0159] The dispersed particle size refers to the particle size of a single particle of the near-infrared absorbing material dispersed in the near-infrared absorbing material particle dispersion liquid, or the particle size of an aggregated particle of the near-infrared absorbing material particles.

[0160] In a near-infrared absorbing material particle dispersion, near-infrared absorbing material particles aggregate to form coarse aggregates, and if a large number of such coarse particles are present, the coarse particles become a source of light scattering. As a result, when a near-infrared absorbing material particle dispersion such as a near-infrared absorbing film or a molded product is produced using the near-infrared absorbing material particle dispersion, the haze increases, which may cause a decrease in visible light transmittance. Therefore, it is preferable to thoroughly disperse the near-infrared absorbing material particles to avoid the generation of coarse particles. 4. Near-infrared absorbing material particle dispersion The near-infrared absorbing particle dispersion of this embodiment may contain the near-infrared absorbing material particles described above and a solid medium. The near-infrared absorbing material particles are preferably dispersed in the solid medium.

[0161] The near-infrared absorbing material particle dispersion of this embodiment can be obtained by dispersing the above-described near-infrared absorbing material particles in an appropriate solid medium.

[0162] The near-infrared absorbing material particle dispersion of the present embodiment is prepared by, for example, mechanically pulverizing near-infrared absorbing material particles under predetermined conditions, dispersing the particles in a solid medium such as a resin, and maintaining the dispersed state. Therefore, the near-infrared absorbing material particle dispersion can be applied to base materials with low heat resistance temperatures, such as resin materials, and has the advantages of being inexpensive and not requiring large-scale equipment for formation.

[0163] Since the near-infrared absorbing material of this embodiment is a conductive material, when it is used as a continuous film, there is a risk that it will absorb and reflect and interfere with radio waves from mobile phones, etc. However, when the near-infrared absorbing material is dispersed as particles in a matrix of a solid medium, each particle is dispersed in an isolated state, and therefore radio wave transparency can be exhibited, making it versatile.

[0164] The average particle size of the near-infrared absorbing material particles dispersed in the matrix of the solid medium of the near-infrared absorbing material particle dispersion may differ from the dispersed particle size of the near-infrared absorbing material particles dispersed in the near-infrared absorbing material particle dispersion liquid or the dispersion liquid for forming the near-infrared absorbing material particle dispersion used to form the near-infrared absorbing material particle dispersion. This is because, when the near-infrared absorbing material particle dispersion is obtained from the near-infrared absorbing material particle dispersion liquid or the dispersion liquid for forming the near-infrared absorbing material particle dispersion, the agglomerates of the near-infrared absorbing material particles that have agglomerated in the dispersion liquid are released.

[0165] The solid medium for the near-infrared absorbing material particle dispersion is not particularly limited, but for example, a resin or glass can be used.

[0166] When a resin is used as the solid medium, the type of resin is not particularly limited, but the resin may be one or more selected from, for example, polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polystyrene resin, polyamide resin, polyethylene resin, vinyl chloride resin, polyvinyl butyral resin, polyester resin, olefin resin, epoxy resin, polyimide resin, fluororesin, ethylene-vinyl acetate copolymer resin, and polyvinyl acetal resin.

[0167] The content of near-infrared absorbing material particles in the near-infrared absorbing material particle dispersion is not particularly limited, but the near-infrared absorbing material particle dispersion preferably contains near-infrared absorbing material particles in a proportion of 0.001% by mass or more and 80% by mass or less. This is because a near-infrared absorbing material particle content of 0.001% by mass or more can exhibit sufficient near-infrared shielding function. Furthermore, by setting the content of near-infrared absorbing material particles to 80% by mass or less, the proportion of solid medium contained in the near-infrared absorbing material particle dispersion can be increased, thereby increasing the strength of the dispersion.

[0168] The shape of the near-infrared absorbing material particle dispersion of this embodiment is not particularly limited and can be arbitrarily selected depending on the application, etc. For example, the near-infrared absorbing material particle dispersion of this embodiment is preferably in the form of a sheet, a board, or a film.

[0169] The method for producing the near-infrared absorbing material particle dispersion of this embodiment is not particularly limited, and the dispersion can be produced by adding the near-infrared absorbing material particles described above to a solid medium and dispersing them as necessary.

[0170] The near-infrared absorbing material particle dispersion of this embodiment can be produced, for example, by the following procedure.

[0171] First, a dispersion liquid for forming a near-infrared absorbing material particle dispersion can be prepared. The dispersion liquid for forming a near-infrared absorbing material particle dispersion can be prepared, for example, by adding and dissolving a resin as a solid medium to the near-infrared absorbing material particle dispersion. Alternatively, the dispersion liquid can be prepared by adding one or more of a silane coupling agent, a silane alkoxide, a polysilazane, or a polyorganosilane, which is a precursor of a silicate compound or the like that becomes glass, to the near-infrared absorbing material particle dispersion.

[0172] The prepared dispersion liquid for forming a near-infrared absorbing material particle dispersion is then applied to a transparent substrate such as a glass plate, a plastic plate, etc. Next, the dispersion medium of the near-infrared absorbing material particle dispersion contained in the dispersion liquid for forming a near-infrared absorbing material particle dispersion is dried, volatilized, etc., to obtain a near-infrared absorbing transparent substrate having a cured near-infrared absorbing material particle dispersion formed on the surface of the transparent substrate.

[0173] Alternatively, a near-infrared absorbing material particle dispersion can be obtained by kneading near-infrared absorbing material particles or a near-infrared absorbing material particle dispersion into a solid medium. [Example]

[0174] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Example 1] 23.5 g of Cs2CO3 was dissolved in 36 g of water, and this was added to 109 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 1 (raw material preparation step).

[0175] Next, the reaction step was carried out using the raw material mixture prepared in the raw material preparation step, using the hybrid plasma reactor 10 shown in FIG. 1 in which DC plasma and high frequency plasma are superimposed.

[0176] First, the reaction system was evacuated to about 0.1 Pa (about 0.001 torr) using the vacuum exhaust device 13, and then completely replaced with argon gas to create an argon flow system at 1 atmosphere.

[0177] DC plasma was generated by flowing argon gas at 8 L / min through the plasma generating gas supply port 15. The DC power input at this time was 6 kW.

[0178] Furthermore, argon gas at 40 L / min and hydrogen gas at 3 L / min were spirally flowed from the sheath gas inlet 16 along the inner wall of the water-cooled quartz double tube 11 as gases for generating high-frequency plasma and protecting the quartz tube, to generate high-frequency plasma.

[0179] The input of the high frequency power supply was set to 45 kW. After generating such a hybrid plasma, the raw material mixture according to Example 1 was supplied into the plasma from the raw material powder supply device 19 at a supply rate of 2 g / min using a mixed gas of argon gas at 3 L / min and oxygen gas at 0.01 L / min as a carrier gas.

[0180] As a result, the raw material was instantly evaporated and condensed in the plasma tail flame to form fine particles. Particles (cesium tungsten oxide particles a), which are particles of the near-infrared absorbing material, were collected at the bottom of the reaction vessel 12.

[0181] The particle diameter of the collected cesium tungsten oxide particles a was determined by TEM observation, and it was confirmed that the particle diameter of the 30 particles evaluated was 10 nm or more and 50 nm or less. The particle diameter was calculated using the diameter of the smallest circle circumscribing the particle to be evaluated.

[0182] The results of quantitative analysis of Cs, W, and O of the recovered cesium tungsten oxide particles a were 14.7 wt%, 65.5 wt%, and 18.3 wt%, respectively, as shown in Table 1. The chemical formula calculated from the quantitative analysis was Cs 0.31 WO 3.21 We were able to confirm that this is the case.

[0183] Cs was measured using a flame atomic absorption spectrometer (Varian, model: SpectrAA 220FS). W was measured using an ICP optical emission spectrometer (Shimadzu, model: ICPE9000). O was measured using an oxygen / nitrogen simultaneous analyzer (Leco, model: ON836). The same applies to the other examples and comparative examples below.

[0184] The X-ray diffraction pattern of the cesium tungsten oxide particles a was measured by powder X-ray diffraction (θ-2θ method) using a powder X-ray diffractometer (X'Pert-PRO / MPD manufactured by PANalytical, Spectris Co., Ltd.). The crystal structure of the compound contained in the cesium tungsten oxide particles a was identified from the obtained X-ray diffraction pattern, and it was found to be a hexagonal Cs 0.3 The same peaks as those of WO3 were confirmed. As described above, the crystal structure of the obtained composite tungsten oxide can be identified by the X-ray diffraction pattern. In the case of this example, as described above, the crystal structure of the compound contained in the composite tungsten oxide particles matches the peaks of a similar hexagonal composite tungsten oxide. Therefore, it can be confirmed that the crystal structure of the composite tungsten oxide obtained in this example, i.e., cesium tungsten oxide, is hexagonal.

[0185] 20.0 mass% of cesium tungsten oxide particles a, 16.0 mass% of an acrylic polymer dispersant having an amine-containing functional group (an acrylic dispersant with an amine value of 48 mg KOH / g and a decomposition temperature of 250°C) (hereinafter referred to as "dispersant a"), and 64.0 mass% of methyl isobutyl ketone as a dispersion medium were weighed out, and loaded into a paint shaker (manufactured by Asada Iron Works) containing 0.3 mm diameter ZrO2 beads. A near-infrared absorbing material particle dispersion liquid (Liquid A-1) was prepared by crushing and dispersing the particles for 50 minutes.

[0186] Here, the dispersed particle diameter of the cesium tungsten oxide particles a in the near-infrared absorbing material particle dispersion liquid (liquid A-1) was measured using a particle size measuring device (ELS-8000 manufactured by Otsuka Electronics Co., Ltd.) based on the dynamic light scattering method, and was found to be 50 nm.

[0187] In addition, the dispersion medium was removed from the near-infrared absorbing material particle dispersion liquid (A-1 liquid), and the recovered near-infrared absorbing material particles were measured for their X-ray diffraction pattern using a powder X-ray diffractometer (X'Pert-PRO / MPD manufactured by PANalytical, Spectris Co., Ltd.). The crystallite diameter was determined from the X-ray diffraction pattern by the Rietveld method, and the crystallite diameter was found to be 25.0 nm. In addition, the lattice constants determined by the Rietveld method were 7.4099 Å for the a-axis and 7.6090 Å for the c-axis. In the following other examples and comparative examples, the crystallite diameter and lattice constant were also determined by the Rietveld method.

[0188] Next, the obtained near-infrared absorbing material particle dispersion liquid (Liquid A-1) and a UV curable resin (Aronix UV-3701 (Toa Gosei Co., Ltd.)) were weighed out to a weight ratio of 1:9, and mixed and stirred to prepare a dispersion liquid for forming a near-infrared absorbing material particle dispersion (Liquid AA-1).

[0189] Then, using a bar coater with bar No. 16, the dispersion liquid for forming a near-infrared absorbing material particle dispersion (AA-1 liquid) was applied onto a soda-lime glass substrate with a thickness of 3 mm, and then dried under conditions of 70° C. for 1 minute. Next, a high-pressure mercury lamp was used to irradiate the coating liquid, thereby obtaining a near-infrared absorber A, which is a near-infrared absorbing material particle dispersion according to Example 1.

[0190] Here, the optical properties of the near-infrared absorber A were measured, and the results were that the visible light transmittance was 69.7% and the solar radiation transmittance was 47.0%.

[0191] The optical properties were measured using a Hitachi U-4000 spectrophotometer. The other optical properties listed below were also measured using the same spectrophotometer. Visible light transmittance and solar radiation transmittance were calculated according to JIS R 3106 (2019).

[0192] After a heat resistance test was conducted in which the near-infrared absorber A was exposed to 120°C in an atmospheric air for 125 hours, the visible light transmittance and solar transmittance were measured. As a result, the solar transmittance after exposure was 45.7%, and the change in solar transmittance before and after exposure at 120°C, ΔST (solar transmittance after exposure - solar transmittance before exposure) was -1.3%, indicating excellent heat resistance.

[0193] Furthermore, using a bar coater with bar No. 22, the dispersion liquid for forming a near-infrared absorbing material particle dispersion (AA-1 liquid) was applied onto a PET film substrate with a thickness of 0.05 mm, and then dried under conditions of 70° C. for 1 minute. Next, a high-pressure mercury lamp was used to irradiate the coating liquid, thereby obtaining a near-infrared absorber B, which is a near-infrared absorbing material particle dispersion according to Example 1.

[0194] The optical properties of the near-infrared absorber B were measured, and the results were that the visible light transmittance was 70.3% and the solar radiation transmittance was 49.6%.

[0195] After a moist heat resistance test was conducted in which the near infrared absorber B was exposed to an atmospheric condition of 85°C and 90% RH for 94 hours, the visible light transmittance and the solar radiation transmittance were measured. As a result, the solar radiation transmittance was 49.3%, and the change ΔST in the solar radiation transmittance before and after the moist heat resistance test was -0.3%, indicating excellent moist heat resistance.

[0196] Hereinafter, the same tests and evaluations as in Example 1 were carried out for Examples 2 to 21 and Comparative Examples 1 and 2. The results are shown in Tables 1 and 2.

[0197] [Table 1]

[0198] [Table 2] [Example 2] Near-infrared absorbing material particles were prepared using a high-frequency plasma reactor 30 shown in FIG.

[0199] The high frequency plasma reactor 30 has a water-cooled quartz double tube 31 and a reaction vessel 32 connected to the water-cooled quartz double tube 31. A vacuum exhaust device 33 is connected to the reaction vessel 32.

[0200] Above the water-cooled quartz double tube 31, a plasma generating gas supply port 34 is provided.

[0201] The water-cooled quartz double tube 31 is configured so that sheath gas for generating high-frequency plasma and for protecting the quartz tube can be supplied along the inner wall thereof, and a sheath gas inlet 36 is provided on the upper flange of the water-cooled quartz double tube 31.

[0202] A water-cooled copper coil 37 for generating high-frequency plasma is arranged around the water-cooled quartz double tube 31 .

[0203] A raw material powder carrier gas supply port 38 is provided near the plasma generating gas supply port 34 and is connected by a pipe to a raw material powder supply device 39 that supplies raw material powder.

[0204] The plasma generating gas supply port 34, sheath gas inlet 36, and raw material powder supply device 39 can be connected to a gas supply device 40 by piping, so that a predetermined gas can be supplied to each component from the gas supply device 40. Note that, if necessary, supply ports other than those for the components mentioned above can be provided and connected to the gas supply device 40 so that the components in the device can be cooled or a predetermined atmosphere can be created.

[0205] In this example, high-frequency plasma was generated by first flowing argon gas at 30 L / min through the plasma generating gas supply port 34, and then supplying a mixture of argon gas at 40 L / min and hydrogen gas at 3 L / min in a spiral fashion through the sheath gas inlet 36. The high-frequency power input at this time was 45 kW.

[0206] Next, the raw material mixture prepared in Example 1 was supplied into the plasma at a rate of 2 g / min from raw material powder supply device 39 using a mixed gas of argon gas at 3 L / min and oxygen gas at 0.01 L / min as a carrier gas.

[0207] As a result, the particle diameter of the near-infrared absorbing material particles recovered at the bottom of the reaction vessel 32 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0208] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 2 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0209] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 2 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 25.2 nm and lattice constants of an a-axis of 7.4146 Å and a c-axis of 7.5995 Å.

[0210] The results are shown in Tables 1 and 2. [Example 3] 6.65 g of Li2CO3 was dissolved in 50 g of water, and this was added to 150 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 3.

[0211] The near-infrared absorbing material particles of Example 3, Li, were prepared in the same manner as in Example 2, except that the raw material mixture of Example 3 was supplied into the plasma in the same manner as in Example 2. 0.31 WO 3.16 A powder of particles was obtained.

[0212] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0213] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 3 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be cubic Li 0.3 The same peak as that of WO3 was confirmed.

[0214] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 3 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 24.9 nm.

[0215] The results are shown in Tables 1 and 2. [Example 4] 2.74 g of Na2CO3 was dissolved in 43 g of water, and this was added to 130 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 4.

[0216] The raw material mixture according to Example 4 was supplied into plasma in the same manner as in Example 2 to form near-infrared absorbing material particles according to Example 4, namely, Na 0.1 WO 3.19 A powder of particles was obtained.

[0217] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0218] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 4 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found that the crystal structure was tetragonal Na 0.1 The same peak as that of WO3 was confirmed.

[0219] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 4 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 25.5 nm.

[0220] The results are shown in Tables 1 and 2. [Example 5] 13.43 g of K2CO3 was dissolved in 59 g of water, and this was added to 180 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 5.

[0221] The raw material mixture according to Example 5 was supplied into the plasma in the same manner as in Example 2 to form composite tungsten oxide particles according to Example 5, K 0.27 WO 3.14 A powder of particles was obtained.

[0222] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0223] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 5 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal K 0.27 The same peak as that of WO3 was confirmed.

[0224] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 5 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the crystallite diameter of the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion was 24.4 nm.

[0225] The results are shown in Tables 1 and 2. [Example 6] 22.17 g of Rb2CO3 was dissolved in 50 g of water, and this was added to 150 g of H2WO4. After sufficient stirring, the mixture was dried to obtain a raw material mixture according to Example 6.

[0226] The raw material mixture according to Example 6 was supplied to the plasma in the same manner as in Example 2 to form the composite tungsten oxide particles according to Example 6, Rb 0.3 WO 3.16 A powder of particles was obtained.

[0227] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0228] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 6 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Rb 0.3 The same peak as that of WO3 was confirmed.

[0229] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 6 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 23.9 nm and lattice constants of 7.3958 Å for the a-axis and 7.5605 Å for the c-axis.

[0230] The results are shown in Tables 1 and 2. [Example 7] 0.16 g of Cu(NO3)23H2O3 was dissolved in 40 g of water, and this was added to 120 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 7.

[0231] The raw material mixture according to Example 7 was supplied into plasma in the same manner as in Example 2 to form composite tungsten oxide particles according to Example 7, 0.2 WO 3.14 A powder of particles was obtained.

[0232] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0233] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 7 was measured by powder X-ray diffraction method (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found that the crystal structure contained in the particles was orthorhombic Cu. 0.26 The same peak as that of WO3 was confirmed.

[0234] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 7 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 26.1 nm.

[0235] The results are shown in Tables 1 and 2. [Example 8] 0.66 g of Ag2CO3 was dissolved in 40 g of water, and this was added to 120 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 8.

[0236] The raw material mixture according to Example 8 was supplied to the plasma in the same manner as in Example 2 to form composite tungsten oxide particles according to Example 8, namely, Ag 0.01 WO 3.16 A powder of particles was obtained.

[0237] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0238] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 8 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be orthorhombic Ag 0.01 The same peak as that of WO3 was confirmed.

[0239] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 8 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 23.7 nm.

[0240] The results are shown in Tables 1 and 2. [Example 9] 6.42 g of CaCO3 was dissolved in 53 g of water, and this was added to 160 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 9.

[0241] The raw material mixture according to Example 9 was supplied to the plasma in the same manner as in Example 2 to form composite tungsten oxide particles according to Example 9, namely, Ca 0.09 WO 3.14 A powder of particles was obtained.

[0242] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0243] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 9 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Ca 0.1 The same peak as that of WO3 was confirmed.

[0244] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 9 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the crystallite diameter of the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion was 23.5 nm.

[0245] The results are shown in Tables 1 and 2. [Example 10] 8.50 g of SrCO3 was dissolved in 59 g of water, and this was added to 180 g of H2WO4. After sufficient stirring, the mixture was dried to obtain a raw material mixture according to Example 10.

[0246] The raw material mixture according to Example 10 was supplied to the plasma in the same manner as in Example 2 to form the composite tungsten oxide particles according to Example 10, Sr 0.01 WO 3.16 A powder of particles was obtained.

[0247] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0248] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 10 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Sr 0.08 The same peak as that of WO3 was confirmed.

[0249] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 10 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the crystallite diameter of the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion was 26.4 nm.

[0250] The results are shown in Tables 1 and 2. [Example 11] 13.26 g of BaCO3 was dissolved in 40 g of water, and this was added to 120 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 11.

[0251] The raw material mixture of Example 11 was supplied into plasma in the same manner as in Example 2 to form composite tungsten oxide particles of Example 11, namely, Ba 0.14 WO 3.14 A powder of particles was obtained.

[0252] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0253] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 11 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Ba 0.14 The same peak as that of WO3 was confirmed.

[0254] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 11 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 24.7 nm.

[0255] The results are shown in Tables 1 and 2. [Example 12] 1.67 g of In2O3 and 150 g of H2WO4 were thoroughly mixed in a mortar to obtain a raw material mixture according to Example 12.

[0256] The raw material mixture of Example 12 was supplied into plasma in the same manner as in Example 2 to form the composite tungsten oxide particles of Example 12, In 0.02 WO 3.18 A powder of particles was obtained.

[0257] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0258] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 12 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be tetragonal In 0.02 The same peak as that of WO3 was confirmed.

[0259] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 12 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 25.0 nm.

[0260] The results are shown in Tables 1 and 2. [Example 13] 12.15 g of TlNO3 was dissolved in 180 g of water, and this was added to 60 g of H2WO. The mixture was thoroughly stirred and then dried to obtain a raw material mixture according to Example 13.

[0261] The raw material mixture of Example 13 was supplied to the plasma in the same manner as in Example 2 to form the composite tungsten oxide particles of Example 13, Tl 0.19 WO 3.19 A powder of particles was obtained.

[0262] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0263] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 13 was measured by powder X-ray diffraction method (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Tl 0.19 The same peak as that of WO3 was confirmed.

[0264] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 13 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 26.4 nm.

[0265] The results are shown in Tables 1 and 2. [Example 14] 17.18 g of SnO2 and 150 g of H2WO4 were thoroughly mixed in a mortar to obtain a raw material mixture according to Example 14.

[0266] The raw material mixture of Example 14 was supplied to plasma in the same manner as in Example 2 to form composite tungsten oxide particles of Example 14, Sn 0.19 WO 3.16 A powder of particles was obtained.

[0267] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0268] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 14 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be tetragonal Sn 0.19 The same peak as that of WO3 was confirmed.

[0269] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 14 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 23.9 nm.

[0270] The results are shown in Tables 1 and 2. [Example 15] 17.98 g of Yb2O3 and 120 g of H2WO4 were thoroughly mixed in a mortar to obtain a raw material mixture according to Example 15.

[0271] The raw material mixture of Example 15 was supplied to the plasma in the same manner as in Example 2 to form composite tungsten oxide particles of Example 15, namely, Yb 0.18 WO 3.16 A powder of particles was obtained.

[0272] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0273] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 15 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be cubic Yb 0.19 The same peak as that of WO3 was confirmed.

[0274] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 15 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the crystallite diameter of the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion was 24.3 nm.

[0275] The results are shown in Tables 1 and 2. [Example 16] 17.25 g of Snowtex S manufactured by Nissan Chemical Industries, Ltd. and 150 g of H2WO4 were thoroughly mixed in a mortar and then dried to obtain a raw material mixture according to Example 16.

[0276] The raw material mixture of Example 16 was supplied into plasma in the same manner as in Example 2 to form composite tungsten oxide particles of Example 16, Si 0.04 WO 3.14 A powder of particles was obtained.

[0277] The particle diameter of the recovered near-infrared absorbing material particles was found to be 10 nm or more and 50 nm or less by TEM observation.

[0278] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 16 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be cubic Si 0.04 WO 2.839 The same peak was observed.

[0279] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 16 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 26.2 nm.

[0280] The results are shown in Tables 1 and 2. [Example 17] Composite tungsten oxide particles according to Example 17 were produced and evaluated in the same manner as in Example 2, except that a mixed gas of 5 L / min of argon gas and 0.01 L / min of oxygen gas was used as the carrier gas.

[0281] The particle diameter of the near-infrared absorbing material particles recovered from the high-frequency plasma reactor 30 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0282] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 17 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0283] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 17 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 24.5 nm. The lattice constants determined by the Rietveld method were a-axis 7.4148 Å and c-axis 7.5995 Å.

[0284] The results are shown in Tables 1 and 2. [Example 18] Composite tungsten oxide particles according to Example 18 were produced and evaluated in the same manner as in Example 2, except that a mixed gas of 4 L / min of argon gas and 0.01 L / min of oxygen gas was used as the carrier gas.

[0285] The particle diameter of the near-infrared absorbing material particles recovered from the high-frequency plasma reactor 30 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0286] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 18 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0287] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 18 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 21.7 nm. The lattice constants determined by the Rietveld method were an a-axis of 7.4116 Å and a c-axis of 7.5955 Å.

[0288] The results are shown in Tables 1 and 2. [Example 19] In Example 2, a mixed gas of argon gas at 5 L / min and oxygen gas at 0.02 L / min was used as the carrier gas, and the raw material mixture prepared in Example 1 was supplied into the plasma at a rate of 2.5 g / min. In the same manner as in Example 2, composite tungsten oxide particles according to Example 19 were produced and evaluated.

[0289] The particle diameter of the near-infrared absorbing material particles recovered from the high-frequency plasma reactor 30 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0290] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 19 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0291] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 18 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 19.1 nm. The lattice constants determined by the Rietveld method were a-axis 7.4137 Å and c-axis 7.6029 Å.

[0292] The results are shown in Tables 1 and 2. [Example 20] In Example 2, a mixed gas of argon gas at 4.5 L / min and oxygen gas at 0.02 L / min was used as the carrier gas, and the raw material mixture prepared in Example 1 was supplied into the plasma at a rate of 2.5 g / min. In the same manner as in Example 2, composite tungsten oxide particles according to Example 20 were produced and evaluated.

[0293] The particle diameter of the near-infrared absorbing material particles recovered from the high-frequency plasma reactor 30 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0294] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Example 20 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0295] A near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particles of Example 18 were used. The dispersion medium was removed from the near-infrared absorbing material particle dispersion, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, recovered from the dispersion had a crystallite diameter of 16.8 nm. The lattice constants determined by the Rietveld method were an a-axis of 7.4149 Å and a c-axis of 7.5997 Å.

[0296] The results are shown in Tables 1 and 2. [Example 21] 14.0% by mass of the near-infrared absorbing material particles obtained in Example 19 and 86.0% by mass of pure water were weighed, loaded into a paint shaker (manufactured by Asada Iron Works) containing 0.3 mm diameter ZrO2 beads, and subjected to a 50-minute crushing and dispersion process to prepare a dispersion for forming a coating film. While stirring the dispersion, a 44.0% by mass solution of aluminum ethyl acetoacetate diisopropylate as an aluminum-based chelate compound in isopropyl alcohol (IPA) was added dropwise over 5 hours. Next, the medium was evaporated using a large vacuum crusher to obtain a surface-treated near-infrared absorbing material particle powder according to Example 21. These infrared absorbing material particles were coated with an Al-containing compound.

[0297] 20.0 mass% of the surface-treated near-infrared absorbing material particles, 16.0 mass% of dispersant a, and 64.0 mass% of methyl isobutyl ketone as a dispersion medium were weighed out, and loaded into a paint shaker (manufactured by Asada Iron Works) containing 0.3 mmφZrO beads, and subjected to a dispersion treatment for 1 minute to prepare a near-infrared absorbing material particle dispersion liquid according to Example 21.

[0298] A near-infrared absorbing material particle dispersion was prepared and evaluated in the same manner as in Example 1, except that the near-infrared absorbing material particle dispersion liquid of Example 21 was used.

[0299] The results are shown in Table 2. [Comparative Example 1] The cesium tungsten oxide particles a obtained in Example 1 were fired at 500°C for 1 hour in an atmosphere of 0.3% H2 gas with N2 gas as a carrier gas to prepare near-infrared absorbing material particles according to Comparative Example 1.

[0300] The near-infrared absorbing material particles according to Comparative Example 1 were coarser than the near-infrared absorbing material particles according to Example 1 due to the effect of firing at 500°C for 1 hour under a 3% H gas atmosphere. Therefore, a near-infrared absorbing material particle dispersion and a near-infrared absorbing material particle dispersion were prepared and evaluated in the same manner as in Example 1, except that the dispersion and pulverization time for the near-infrared absorbing material particle dispersion was set to 2 hours and the near-infrared absorbing material particles according to Comparative Example 1 were used.

[0301] The X-ray diffraction pattern of the obtained near-infrared absorbing material particles according to Comparative Example 1 was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed. Furthermore, the dispersion medium was removed from the near-infrared absorbing material particle dispersion liquid, and the composite tungsten oxide particles, which were near-infrared absorbing material particles, were recovered. The crystallite diameter of the particles was 9 nm, and the lattice constants thereof were an a-axis of 7.4100 Å and a c-axis of 7.6300 Å.

[0302] The results are shown in Tables 1 and 2. Comparative Example 2 A solution was obtained by dissolving 55.45 g of cesium carbonate (Cs2CO3) in 50 g of water. This solution was added to 286 g of tungstic acid (H2WO4) and thoroughly mixed, then dried while stirring. The molar ratio of W to Cs in the dried product was W:Cs = 1:0.33.

[0303] The dried product was calcined at 800 °C for 5.5 hours in an atmosphere of 5% H2 gas with N2 gas as the carrier gas, and then the supply gas was switched to only N2 gas and cooled to room temperature to obtain cesium tungsten oxide particles, which are near-infrared absorbing material particles according to Comparative Example 2.

[0304] The X-ray diffraction pattern of the near-infrared absorbing material particles according to Comparative Example 2 was measured by the powder X-ray diffraction method (θ-2θ method). When the crystal structure contained in the particles was specified from the obtained X-ray diffraction pattern, the same peaks as those of hexagonal Cs 0.3 WO3 were confirmed.

[0305] 20.0% by mass of the near-infrared absorbing material particles according to Comparative Example 2, 16.0% by mass of the dispersant a, and 64.0% by mass of methyl isobutyl ketone were weighed and loaded into a paint shaker (manufactured by Asada Iron Works Co., Ltd.) containing 0.3 mmφ ZrO2 beads, and pulverized and dispersed for 30 hours to prepare a dispersion of near-infrared absorbing material particles according to Comparative Example 2.

[0306] In addition, a near-infrared absorbing material particle dispersion was prepared in the same manner as in Example 1 except that the dispersion of near-infrared absorbing material particles according to Comparative Example 2 was used. Also, the dispersion medium was removed from the dispersion of near-infrared absorbing material particles, and the crystallite size of the recovered composite tungsten oxide particles, which are near-infrared absorbing material particles, was 9 nm, and its lattice constants were 7.4080 Å for the a-axis and 7.6310 Å for the c-axis.

[0307] The evaluation results are shown in Table 1 and Table 2. (Summary) As is clear from Table 1, the near-infrared absorbing material particles according to Examples 1 to 20 satisfied the relationship of 3.0 < z / y for z and y in the general formula M x W y O z .

[0308] Furthermore, as is clear from Table 2, the near-infrared absorbers of Examples 1 to 21, which were produced using near-infrared absorbing material particle dispersions containing near-infrared absorbing material particles according to Examples 1 to 20, absorbed and blocked sunlight, particularly light in the near-infrared region, at a similar level compared to near-infrared absorbers produced using near-infrared absorbing material particle dispersions containing near-infrared absorbing material particles according to Comparative Examples 1 and 2, while maintaining high transmittance in the visible light region and exhibiting excellent weather resistance. In particular, in Examples 1 to 21, the rate of change (ΔST) in solar transmittance before and after the heat resistance evaluation and the weather resistance evaluation, which are evaluations of moist heat resistance, was nearly zero, or if it changed, the rate of change was negative. A rate of change in solar transmittance exceeding 1 and being positive indicates that the composite tungsten oxide particles deteriorate due to exposure, resulting in a deterioration in their ability to absorb infrared light. For these reasons, the results in Table 2 demonstrate that the composite tungsten oxide particles of this embodiment have excellent weather resistance.

[0309] The near-infrared absorbing material particles, the near-infrared absorbing material particle dispersion, and the near-infrared absorbing material particle dispersion have been described above in terms of embodiments and examples, but the present invention is not limited to the above embodiments and examples, etc. Various modifications and changes are possible within the scope of the gist of the present invention as set forth in the claims.

[0310] This application claims priority based on Japanese Patent Application No. 2019-234889, filed with the Japan Patent Office on December 25, 2019, the entire contents of which are incorporated herein by reference.

Claims

1. General formula M ｘ W ｙ O ｚ (wherein M element is one or more elements selected from Cs and Rb, W is tungsten, O is oxygen, 0.20≦x / y≦0.37, 3.0<z / y<3.4), The composite tungsten oxide has a hexagonal crystal structure, The lattice constant of the composite tungsten oxide is such that the a-axis is 7.3850 Å or more and 7.4186 Å or less, and the c-axis is 7.5600 Å or more and 7.6240 Å or less, Near-infrared absorbing material particles having a particle diameter of 10 nm or more and 100 nm or less.

2. 2. The near-infrared absorbing material particles according to claim 1, wherein the composite tungsten oxide particles also contain crystals having one or more crystal structures selected from a tetragonal crystal and a cubic crystal.

3. 3. The near-infrared absorbing material particle according to claim 1, wherein the surface of the near-infrared absorbing material particle is coated with a compound containing one or more elements selected from the group consisting of Si, Ti, Zr, and Al.

4. Particles of the near-infrared absorbing material according to any one of claims 1 to 3; A near-infrared absorbing material particle dispersion liquid comprising: a dispersion medium;

5. Particles of the near-infrared absorbing material according to any one of claims 1 to 3; a solid medium; and a near-infrared absorbing material particle dispersion comprising:

6. 6. The near-infrared absorbing material particle dispersion according to claim 5, wherein the solid medium is a resin or glass.

7. 7. The near-infrared absorbing material particle dispersion according to claim 6, wherein the resin is at least one selected from the group consisting of polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polystyrene resin, polyamide resin, polyethylene resin, vinyl chloride resin, polyvinyl butyral resin, polyester resin, olefin resin, epoxy resin, polyimide resin, fluororesin, ethylene-vinyl acetate copolymer resin, and polyvinyl acetal resin.

8. 8. The near-infrared absorbing material particle dispersion according to claim 5, wherein the near-infrared absorbing material particles are contained in an amount of 0.001% by mass or more and 80% by mass or less.

9. The near-infrared absorbing material particle dispersion according to any one of claims 5 to 8, which is in the form of a sheet, a board, or a film.

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