Infrared-absorbing fiber and fiber product

Abstract

The present invention addresses the problem of providing infrared-absorbing fibers containing composite tungsten oxide particles having excellent infrared absorption performance.　Infrared-absorbing fibers according to the present invention each include a fiber and composite tungsten oxide particles disposed at one or more locations selected from the inside and surfaces of the fiber. The composite tungsten oxide particles contain a composite tungsten oxide. The composite tungsten oxide is represented by general formula MxWyOz (0.20≤x / y≤0.37, 2.2≤z / y≤3.3) and has a hexagonal crystal system. In a STEM-HAADF image of the composite tungsten oxide particles obtained through [001] incidence, the proportion of the number of spots included therein at which the Z-contrast of tungsten atoms has reduced to 95% or less of the average is 0.01-10%.

Description

Infrared absorbing fibers and textile products

[0001] The present invention relates to infrared absorbing fibers and textile products.

[0002] Functional cold weather clothing with heat-retaining and heat-generating functions has been proposed. There are three main methods for improving the cold weather protection effect.

[0003] The first method is to maintain heat retention by reducing the dissipation of heat generated by the human body.

[0004] A specific example of the first method is to control the woven or knitted structure of cold weather clothing, or to make the fibers used hollow or porous, thereby physically increasing the air space and reducing the dissipation of heat generated by the human body to the outside, thereby maintaining heat retention.

[0005] The second method is to utilize the chemical and physical properties of the fibers contained in cold weather clothing so that the fibers themselves store heat.

[0006] The third method is to store heat through active methods, such as chemically or physically processing the fibers contained in cold weather clothing to radiate the heat generated by the human body back towards the human body, or converting some of the sunlight received by the cold weather clothing into heat.

[0007] As one of the second methods, Patent Document 1 discloses a technology that utilizes the latent heat of phase transition of paraffin-based hydrocarbons for heat storage.

[0008] As a third method, a method has been proposed in which ceramic particles such as alumina, zirconia, and magnesia are kneaded into the fiber itself to utilize the far-infrared radiation effect and the ability to convert light into heat that these inorganic particles have, or a method has been proposed in which dyes with high absorption in the near-infrared region are used.In other words, methods have been proposed in which external energy is actively taken in.

[0009] For example, Patent Document 2 describes a material with a thermal conductivity of 0.3 kcal / m ２ The present invention discloses a heat-radiating fiber characterized by containing one or more inorganic fine particles having heat-radiating properties and containing at least one of metals and metal ions having a temperature of .25°C or higher.

[0010] Patent Document 3 discloses a near-infrared absorbing processing method for a cellulosic fiber structure in which a dye having a higher absorption property in the near-infrared region than a black dye is combined with another dye to achieve a spectral reflectance of 65% or less in the near-infrared absorption range of 750 to 1500 nm. Examples of dyes that have a higher absorption property in the near-infrared region than a black dye include direct dyes, reactive dyes, naphthol dyes, and vat dyes.

[0011] In Patent Document 4, the applicant proposes a technology for a near-infrared absorbing fiber and a textile product using the fiber, characterized in that the near-infrared absorbing fiber contains ultrafine particles having near-infrared absorbing properties inside the fiber, the ultrafine particles having near-infrared absorbing properties are composite tungsten oxide ultrafine particles, and the composite tungsten oxide ultrafine particles have an XRD peak top intensity ratio of 0.13 or more when the XRD peak intensity value of the (220) plane of a silicon powder standard sample (640c, manufactured by NIST) is set to 1.

[0012] However, when a human body is photographed using a CCD camera or the like with natural light as a light source, the infrared rays contained in the natural light are transmitted through clothing to photograph the human body, and in recent years, criminal acts exploiting this phenomenon, known as voyeurism, have become a social problem. To solve this problem, infrared-shielding fibers that absorb or reflect infrared rays have been produced, and clothing made from these infrared-shielding fibers (infrared-shielding fiber structures) has been developed.

[0013] For example, Patent Document 5 discloses a knitted fabric obtained by adhering an infrared absorbing agent selected from anthraquinone-based, indigo-based, benzoquinone-based, naphthoquinone-based, or phthalocyanine-based agents to a core-sheath type synthetic fiber.

[0014] Japanese Unexamined Patent Publication No. 2018-135605 Japanese Unexamined Patent Publication No. 11-279830 Japanese Unexamined Patent Application No. 9-291463 International Publication No. 2018 / 235839 Japanese Unexamined Patent Application No. 2008-223171

[0015] Incidentally, in order to prevent so-called surreptitious photography, it is necessary to suppress the content of infrared absorbing particles in infrared absorbing fibers so as not to impair the texture of the fibers while preventing the transmission and reflection of infrared light. Therefore, there is a demand for infrared absorbing fibers containing infrared absorbing particles that have excellent infrared absorbing performance.

[0016] Therefore, one aspect of the present invention aims to provide an infrared absorbing fiber containing composite tungsten oxide particles that has excellent infrared absorbing properties.

[0017] In one aspect of the present invention, a fiber is provided, and composite tungsten oxide particles are disposed at one or more locations selected from the interior and the surface of the fiber, wherein the composite tungsten oxide particles comprise a composite tungsten oxide, and the composite tungsten oxide is represented by the general formula M ｘ W ｙ O ｚ (wherein M element is one or more elements selected from alkali metal elements, alkaline earth metal elements, 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; and 0.20≦x / y≦0.37, 2.2≦z / y≦3.3), the crystal system is hexagonal, The infrared absorbing fiber contains 0.01% to 10% by number of spots in which the Z contrast of tungsten atoms has dropped to 95% or less of the average value in a STEM-HAADF image of the composite tungsten oxide particles from a

[001] incidence angle.

[0018] One aspect of the present invention provides an infrared absorbing fiber containing composite tungsten oxide particles that has excellent infrared absorbing properties.

[0019] FIG. 1 is a schematic diagram of a composite material manufacturing apparatus that can be suitably used in the method for manufacturing composite tungsten oxide particles of this embodiment. FIG. 2 is an explanatory diagram of a reduction treatment apparatus used in the reduction treatment step. FIG. 3 is a schematic diagram of an infrared absorbing particle dispersion. FIG. 4 is a schematic diagram of an infrared absorbing fiber. FIG. 5 is a schematic diagram of the crystal structure of composite tungsten bronze observed with

[001] incidence. FIG. 6 is an XRD pattern of the composite tungsten oxide particles obtained in Example 1. FIG. 7A is a STEM-HAADF image of the composite tungsten oxide particles obtained in Example 1. FIG. 7B is a STEM-HAADF image of the composite tungsten oxide particles obtained in Example 1. FIG. 8A is a line profile quantifying the Z contrast of tungsten atoms along line L1 in FIG. 7B. FIG. 8B is a line profile quantifying the Z contrast of tungsten atoms along line L2 in FIG. 7B. FIG. 8C is a line profile quantifying the Z contrast of tungsten atoms along line L3 in FIG. 7B. FIG. 8D is a line profile quantifying the Z contrast of tungsten atoms along line L4 in FIG. 7B. FIG. 8E is a line profile quantifying the Z contrast of tungsten atoms along line L5 in FIG. 7B. FIG. 8F is a line profile quantifying the Z contrast of tungsten atoms along line L6 in FIG. 7B. FIG. 9A is a STEM-HAADF image of a composite tungsten oxide particle obtained in Comparative Example 1. FIG. 9B is a STEM-HAADF image of a composite tungsten oxide particle obtained in Comparative Example 1. FIG. 10A is a STEM-HAADF image of a composite tungsten oxide particle obtained in Comparative Example 1. FIG. 10B is a line profile quantifying the Z contrast of tungsten atoms in a composite tungsten oxide particle obtained in Comparative Example 1. Fig. 10C is a line profile quantifying the Z contrast of tungsten atoms in the composite tungsten oxide particles obtained in Comparative Example 1. Fig. 10D is a line profile quantifying the Z contrast of tungsten atoms in the composite tungsten oxide particles obtained in Comparative Example 1. Fig. 11A is a transmitted light profile of the near-infrared absorbing particle dispersion liquid according to Example 1.FIG. 11B is a transmitted light profile of a near-infrared absorbing particle dispersion liquid according to Comparative Example 1. FIG. 12A is a STEM-HAADF image of a composite tungsten oxide particle according to Example 1, taken from a

[110] incidence angle. FIG. 12B is a STEM-HAADF image of a composite tungsten oxide particle according to Example 1, taken from a

[110] incidence angle. FIG. 13 is a schematic diagram showing the arrangement of W atoms and Cs atoms in FIG. 12B. FIG. 14A is an XPS spectrum of W atoms in a composite tungsten oxide particle obtained in Example 1. FIG. 14B is an XPS spectrum of W atoms in a composite tungsten oxide particle obtained in Comparative Example 1. FIG. 15A is a molar absorption coefficient curve of a composite tungsten oxide particle obtained in Example 1. FIG. 15B is a molar absorption coefficient curve of a composite tungsten oxide particle obtained in Comparative Example 1. FIG. 16A shows the reflectance of a knit fabric for evaluating voyeurism prevention obtained in Example 1. FIG. 16B shows the reflectance of the knit fabric for evaluation of voyeurism prevention obtained in Comparative Example 1.

[0020] Specific examples of infrared-absorbing fibers and textile products according to one embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0021] Before describing the infrared absorbing fiber, the composite tungsten oxide particles contained in the infrared absorbing fiber of this embodiment will be described. [Composite tungsten oxide particles] The composite tungsten oxide particles contain a composite tungsten oxide. Note that the composite tungsten oxide particles may be composed of a composite tungsten oxide, but this does not exclude the inclusion of inevitable impurities even in this case.

[0022] The composite tungsten oxide is represented by the general formula M ｘ W ｙ O ｚ It is expressed as:

[0023] However, the M element in the above general formula is an alkali metal element, an alkaline earth metal element, a rare earth element, Mg (magnesium), Zr (zirconium), Cr (chromium), Mn (manganese), Fe (iron), Ru (ruthenium), Co (cobalt), Rh (rhodium), Ir (iridium), Ni (nickel), Pd (palladium), Pt (platinum), Cu (copper), Ag (silver), Au (gold), Zn (zinc), Cd (cadmium), Al (aluminum), Ga (gallium), In (indium), Tl (thallium), The element may be one or more elements selected from the group consisting of tungsten (W), silicon (Si), germanium (Ge), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), boron (B), fluorine (F), phosphorus (P), sulfur (S), selenium (Se), bromine (Br), tellurium (Te), titanium (Ti), niobium (Nb), vanadium (V), molybdenum (Molybdenum), tantalum (Ta), rhenium (Re), beryllium (Be), hafnium (Hf), osmium (Os), bismuth (Bi), and iodine (I). W represents tungsten, O represents oxygen, and x, y, and z preferably satisfy the relationships 0.20≦x / y≦0.37 and 2.2≦z / y≦3.3, respectively.

[0024] Examples of alkali metal elements include Li (lithium), Na (sodium), K (potassium), Rb (rubidium), Cs (cesium), and Fr (francium). Examples of alkaline earth metal elements include Ca (calcium), Sr (strontium), Ba (barium), and Ra (radium). Examples of rare earth elements include Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium).

[0025] The crystalline system of the composite tungsten oxide is hexagonal.

[0026] The composite tungsten oxide particles contain 0.01% to 10% by number of spots in which the Z contrast of tungsten atoms has dropped to 95% or less of the average value in a STEM-HAADF image of the composite tungsten oxide particles from

[001] incidence. (1) Regarding the composition The composite tungsten oxide contained in the composite tungsten oxide particles is a compound represented by the general formula M ｘ W ｙ O ｚ The M element, W, O, x, y, and z in the formula have already been described, and therefore will not be described here.

[0027] The composite tungsten oxide can have one or more tungsten bronze-type crystal structures selected from, for example, a tetragonal crystal structure, a cubic crystal structure, and a hexagonal crystal structure. The composite tungsten oxide contained in the composite tungsten oxide particles of this embodiment is a hexagonal crystal structure.

[0028] When the composite tungsten oxide has a hexagonal crystal structure, the particles have improved transmittance in the visible light region and improved absorption of light in the near-infrared region.

[0029] Composite tungsten oxides function as infrared-shielding materials even when they have a tetragonal or cubic tungsten bronze-type crystal structure. However, the absorption position of light in the near-infrared region tends to change depending on the crystal structure of the composite tungsten oxide. The absorption position of light in the near-infrared region tends to shift toward longer wavelengths in the tetragonal crystal compared to the cubic crystal, and further shift toward longer wavelengths in the hexagonal crystal compared to the tetragonal crystal. In addition, accompanying this shift in absorption position, hexagonal crystals absorb the least light in the visible light region, followed by tetragonal crystals, and of these, cubic crystals absorb the most light in the visible light region. Therefore, for applications requiring more light in the visible light region to be transmitted and more light in the infrared region to be shielded, it is preferable to use a composite tungsten oxide having a hexagonal tungsten bronze-type crystal structure.

[0030] As described above, when the composite tungsten oxide has a hexagonal crystal structure, the transmittance of the composite tungsten oxide particles in the visible light region and the absorption of the light in the near-infrared region are particularly improved.For this reason, it is preferable that the composite tungsten oxide particles contain a composite tungsten oxide with a hexagonal crystal structure.And, when one or more elements selected from Cs, Rb, K, Tl, Ba, and In are used as the M element, it is easy to form a hexagonal crystal.For this reason, it is preferable that the M element contains one or more elements selected from Cs, Rb, K, Tl, Ba, and In, and it is more preferable that the M element contains one or more elements selected from Rb and Cs.

[0031] Here, the arrangement of the M element when the composite tungsten oxide has a hexagonal crystal structure will be described.

[0032] An octahedron formed by a unit of a W (tungsten) atom and six O (oxygen) atoms, i.e., an octahedron with O atoms at the vertices and a W atom in the center, is assembled into six units to form a hexagonal void (tunnel) composed of O atoms. An M element is then placed in the void to form one unit, and many of these units are assembled to form a hexagonal crystal structure.

[0033] When a composite tungsten oxide having a hexagonal crystal structure has a uniform crystal structure, the ratio of the amount of substance of the M element to W is 0.20≦x / y≦0.37, preferably 0.25≦x / y≦0.37, and more preferably 0.30≦x / y≦0.36. Theoretically, when z / y=3, the value of x / y becomes 0.33, and it is considered that the M element is arranged in all of the hexagonal voids. Note that the above x, y, and z are the same as those in the general formula M described above. ｘ W ｙ O ｚ In the above equation, x, y, and z are used, and so on.

[0034] The composite tungsten oxide is tungsten trioxide (WO ３) and the M element is added. Since tungsten trioxide does not contain effective free electrons, the infrared absorption effect cannot be achieved unless the ratio of oxygen to 1 mole of tungsten is less than 3. However, in composite tungsten oxide, the addition of the M element generates free electrons, and the infrared absorption effect can be achieved. Therefore, the ratio of oxygen to 1 mole of tungsten can be 3 or less. Furthermore, the ratio of oxygen to 1 mole of tungsten may exceed 3. However, WO ２ The crystalline phase of WO may cause absorption or scattering of light in the visible light region, and may reduce absorption of light in the near-infrared region. ２ From the viewpoint of suppressing the formation of , the ratio of oxygen to 1 mole of tungsten is preferably set to be greater than 2.

[0035] Therefore, z / y, which is the ratio of oxygen to 1 mole of tungsten, preferably satisfies 2.2≦z / y≦3.3 as described above. (2) Regarding the average particle size When the composite tungsten oxide particles of this embodiment are used for applications requiring transparency, for example, the composite tungsten oxide particles preferably have an average particle size of 800 nm or less. This is because particles with an average particle size of 800 nm or less do not completely block light due to scattering, and can maintain high visibility in the visible light range while simultaneously efficiently maintaining transparency. In particular, when transparency in the visible light range is important, it is preferable to further consider the scattering of light in the visible light range by the particles.

[0036] When emphasis is placed on reducing scattering of light in the visible light range by such particles, the average particle size is more preferably 200 nm or less, and even more preferably 100 nm or less.

[0037] This is because a small average particle size can suppress light scattering, thereby suppressing unintended gloss in the visible light range and the occurrence of unintended color tones due to light scattering whose intensity is wavelength-dependent (Rayleigh scattering).

[0038] Furthermore, if coarse particles are present in the process of kneading the composite tungsten oxide particles of this embodiment into fibers, the yarn may be broken during spinning. From this perspective, it is preferable to reduce the particle size of the composite tungsten oxide particles.

[0039] Therefore, the composite tungsten oxide particles of this embodiment preferably have an average particle size of 800 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. The lower limit of the average particle size of the composite tungsten oxide particles of this embodiment is not particularly limited, but is preferably, for example, 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more.

[0040] For the above reasons, the average particle size of the composite tungsten oxide particles is preferably 1 nm or more and 800 nm or less, more preferably 5 nm or more and 200 nm or less, even more preferably 10 nm or more and 200 nm or less, and even more preferably 10 nm or more and 100 nm or less.

[0041] The average particle size of composite tungsten oxide particles is calculated by measuring the particle size of each composite tungsten oxide particle from a transmission electron microscope image. Specifically, three fields of view are selected at a magnification that includes 200 or more composite tungsten oxide particles in one field of view, and the image of the composite tungsten oxide particles in each field of view is binarized, and the average particle size is calculated by image analysis. The upper limit of the number of composite tungsten oxide particles in one field of view is not particularly limited, and for example, the magnification may be selected so that one field of view includes 500 or less composite tungsten oxide particles. All composite tungsten oxide particles in the three fields of view may be evaluated, but for example, a total of 500 to 800 particles may be selected, or a total of 600 to 700 particles may be selected in the three fields of view.

[0042] Specifically, the equivalent circle diameter is calculated from the area of ​​each composite tungsten oxide particle, and this is taken as the particle size of the composite tungsten oxide particle. The average particle size can then be calculated by adding up the particle sizes of all the composite tungsten oxide particles evaluated and dividing by the number of particles evaluated. That is, the average particle size can be determined as the arithmetic mean of the particle sizes of the composite tungsten oxide particles evaluated. (3) Atomic Number (Z) Contrast of Tungsten Atoms in Composite Tungsten Oxide Particles In a STEM-HAADF image (STEM-High-Angle Annular Dark Field) from

[001] incidence, the composite tungsten oxide particles of this embodiment preferably contain dark areas in the atomic number (Z) contrast of tungsten atoms (hereinafter also referred to as "Z contrast") of 0.01% to 10%, more preferably 0.1% to 10%, and even more preferably 0.2% to 10%. The STEM-HAADF image of the composite tungsten oxide particle from the

[001] incidence is an image observing the basal plane of the composite tungsten oxide.

[0043] According to the investigations of the inventors of the present invention, the composite tungsten oxide particles can particularly improve the visible light transmittance and infrared shielding performance by having an appropriate amount of minute oxygen vacancies, which are difficult to grasp by XRD patterns and the like.

[0044] Furthermore, by containing 10% or less of the dark areas in the Z contrast of tungsten atoms (hereinafter also referred to as "W atoms") in the composite tungsten oxide particles, the W remaining around the W deficiency region can be oxidized, and the amount of oxygen deficiency can be contained to a degree that is not excessive. Also, by containing 0.01% or more of the dark areas in the Z contrast of W atoms in the composite tungsten oxide particles, oxygen deficiency can be introduced appropriately.

[0045] Dark areas in the Z contrast of W atoms in composite tungsten oxide particles indicate defects of W atoms. The dark areas in the Z contrast of W atoms refer to spots (points) where the Z contrast of W atoms has fallen to 95% or less of the reference value, where the average value of the Z contrast of W atoms included in the observation field of the STEM-HAADF image of the composite tungsten oxide particles is taken as the reference value.

[0046] When observing a STEM-HAADF image, particles that can be observed with

[001] incidence and have a size of several tens of nanometers or more can be selected from the dispersed composite tungsten oxide particles. To extract the contrast of the W atom spot, the observation field size can be set to 20 nm to 50 nm square.

[0047] Figure 5 shows the hexagonal Cs ０．３３ WO ３ 7A and 7B show the relationship between the crystal structure of the (001) plane of Cs obtained in Example 1 and the W atom / W atomic row (hereinafter also referred to as "W / W row"). ０．３３ WO ３ 8A to 8F show the Z contrast of W atoms in the W atom / W atom row along lines L1 to L6 shown in FIG. 7B.

[0048] The spots where dark areas of the Z contrast of W atoms were confirmed have weak contrast, such as points P1 and P2 in Figure 7B, and these spots indicate defects of W atoms. In Figure 7B, the tips of the arrows labeled P1 and so on indicate the above-mentioned dark areas.

[0049] The Z contrast of W atoms can be determined from the image (STEM-HAADF) obtained by observing a sample using a scanning transmission electron microscope (STEM-HAADF) and detecting only the transmitted electrons with large scattering angles among the electrons that have passed through the sample. Here, since the magnitude of the scattering angle is proportional to the square of the atomic number (Z), the higher the atomic number of the element, the brighter the contrast. Therefore, contrast due to differences in composition and elements can be obtained. In the case of composite tungsten bronze, it is possible to distinguish between M elements such as Cs and W atoms based on the difference in contrast.

[0050] In this embodiment, in order to distinguish between areas where W atoms are missing and areas where they are not, the difference in contrast intensity at tungsten columns (W columns), which are spots (points) where tungsten is located, in the STEM-HAADF image is utilized. If W atoms are missing, the maximum value of Z contrast at that spot decreases. Hexagonal Cs ０．３３ WO ３ The W atom vacancy sites on the (001) plane are shown with a contrast lower than the average Z contrast of the spots where the W atoms of the W atom / W atom row are arranged. The spots form columnar W atom vacancy regions extending in the (001) direction. At their largest locations, they extend over 10 nm in the (001) direction. No interconnected W atom vacancies of 5 nm or more are observed on the (001) plane.

[0051] From the process of synthesizing the composite tungsten oxide particles of this embodiment, it will be explained that the Z contrast of W atoms can be confirmed in the STEM-HAADF image of the composite tungsten oxide particles from the

[001] incidence.

[0052] The (001) plane of the hexagonal composite tungsten oxide will be described from the perspective of its crystal structure. As shown in Fig. 5, an octahedron 54 is formed as a unit, each of which is composed of a W atom 51 and six O atoms 52. In other words, six octahedrons 54, each of which has an O atom at each vertex and a W atom 51 in the center, are assembled to form a hexagonal void (tunnel) 55 composed of O atoms 52. In Fig. 5, circles with the same hatching indicate the same atoms.

[0053] An M element 53 is arranged in a hexagonal gap 55 formed by O atoms 52 to form one unit. Furthermore, a large number of these units gather to form a hexagonal crystal structure. The hexagonal gap 55 is parallel to the (001) plane. The (001) plane is also perpendicular to the c-axis. By observing the (001) plane, the M element 53 and the W atom 51 can be crystallographically distinguished from each other.

[0054] The composite tungsten oxide particles of this embodiment include Cs ０．３３ WO ３ The change in the crystal structure of particles during the synthesis process will be explained using particles as an example. The composite tungsten oxide particles of this embodiment are manufactured through a raw material preparation step, an aerosol formation step, a heat treatment step, and a reduction treatment step, as will be described later. The raw material aerosolized in the aerosol formation step is rapidly heated to 500°C or higher in the heat treatment step, and a reaction that converts the raw material into composite tungsten oxide proceeds in a short heating period. Then, after heating, the raw material is rapidly cooled to stop the reaction that converts the raw material into composite tungsten oxide. The composite tungsten oxide particles obtained through the heat treatment step are composed of a hexagonal crystal (Cs ０．３３ WO ３ ) and heterophase (Cs ４ W １１ O ３５ , (Cs ２ O) ０．４４ WO ６ STEM-HAADF image observation of the composite tungsten oxide particles confirms that they contain a large number of missing W atoms. These missing W atoms form Cs-rich regions and contribute to the formation of a heterogeneous phase.

[0055] The composite tungsten oxide particles containing heterogeneous phases obtained through the heat treatment process undergo a reduction treatment process in which oxygen is not supplied, resulting in a rearrangement of the M elements, namely, Cs atoms, W atoms, and O atoms. The rearrangement of the atoms results in a transformation into composite tungsten oxide particles in which dark areas are observed in the Z contrast of W atoms in STEM-HAADF images taken from the

[001] incidence. The dark areas in the Z contrast of W atoms in STEM-HAADF images taken from the

[001] incidence of the composite tungsten oxide particles that have undergone the reduction treatment process are presumed to be traces of the heterogeneous phases and vacancies of W atoms.

[0056] On the other hand, as shown in Comparative Example 1 described below, when composite tungsten oxide particles are synthesized by heating the raw materials in a reducing atmosphere for a longer time than in Example 1 without aerosolizing them, hexagonal single-phase composite tungsten oxide particles can be obtained by adjusting the atmosphere and heating conditions. As shown in Figure 9B, which shows the evaluation results of Comparative Example 1, when the composite tungsten oxide particles prepared without aerosolizing the raw materials are observed in a STEM-HAADF image from the

[001] incidence, almost no dark areas in the Z contrast of W atoms are confirmed.

[0057] The composite tungsten oxide particle of this embodiment may also have a defect plane in the direction perpendicular to the c-axis in a STEM-HAADF image (prism plane) of the composite tungsten oxide particle from

[110] incidence.

[0058] The above-mentioned defect plane is generated by the defect of W atoms. Furthermore, there may be a space in the c-axis direction where atoms of the M element such as cesium and W atoms are not present.

[0059] 12A and 12B are STEM-HAADF images from the

[110] incidence of the composite tungsten oxide particle according to Example 1. In Fig. 12A, the presence of a defect plane 121, which is a defect in the basal plane caused by a defect of a W atom and has a length of about 30 nm in the direction perpendicular to the c-axis, was confirmed. In addition, the presence of a space 122, which is about 3 nm long and does not contain Cs atoms or W atoms, was confirmed in the c-axis direction.

[0060] Fig. 12B is an enlarged view of Fig. 12A. It is believed that the defect plane 121, which is a defect in the basal plane, and the space 122 along the c-axis direction where no Cs or W is present remain as the interface of the crystallized region when the Cs and W atoms are rearranged within the crystal during the heat treatment process.

[0061] Furthermore, it was confirmed that there was a distorted structure in which the crystal structure was shifted by a quarter period across a defect plane 121 caused by a defect of W atoms about 30 nm in length in the direction perpendicular to the c-axis. Figure 13 is a diagram showing a schematic diagram of the arrangement of W atoms and Cs atoms in Figures 12A and 12B.

[0062] As described above, in the composite tungsten oxide particles of this embodiment, dark areas are observed in the Z-contrast of W atoms in the STEM-HAADF image from

[001] incidence, which are presumed to be traces of W atom vacancies before the reduction treatment process. It can be confirmed that the composite tungsten oxide particles of this embodiment before the reduction treatment process in the synthesis process contain a large number of W atom vacancies. These W atom vacancies form Cs-excess regions and contribute to the formation of heterophases other than hexagonal crystals. Furthermore, when rearrangement of W atoms occurs during the reduction treatment process and a hexagonal crystal structure is formed, vacant planes, i.e., basal plane (001) vacancies, may occur in a direction perpendicular to the c-axis. The presence of these vacancies is thought to promote rearrangement of W atoms during the reduction treatment process, maintaining the hexagonal crystal structure. During the process of rearrangement of W atoms to maintain the hexagonal crystal structure, vacant W atoms (vacant planes) are generated on the prism surfaces, presumably maintaining the hexagonal crystal structure in areas where no vacancies occur.

[0063] As described above, in hexagonal composite tungsten oxide, theoretically, when z / y = 3, the value of x / y is 0.33, and thus the M element is most abundantly located. Note that in the above and following descriptions, x, y, and z refer to x, y, and z in the general formula of the composite tungsten oxide particles described above. The mass ratio of the M element to the W element is in the range of 0.20≦x / y≦0.37, preferably 0.25≦x / y≦0.37, and more preferably 0.30≦x / y≦0.36. If the mass ratio of the M element is in the range of 0.20≦x / y≦0.37, the rearrangement of W atoms may cause defects on the prism surface, but the composite tungsten oxide particles can maintain their hexagonal structure and have excellent infrared absorption properties. When the amount of M element is small, such as when x / y is less than 0.20, it is difficult to form a hexagonal crystal structure, and even if a hexagonal crystal structure is formed, the number of free electrons supplied to the 5d orbital of the W atom is small, resulting in poor infrared absorption properties.

[0064] On the other hand, when the ratio of the amount of substance of the M element to the W element (x / y) is greater than 0.37, the M element becomes excessive, and many W atom vacancies occur not only on the prism planes but also on the basal planes, and heterophases such as pyrochlore phases occur in addition to hexagonal crystals, resulting in poor infrared absorption properties. These vacancies on the basal planes are planar or strip-shaped vacancies with a length in the (001) direction of 10 nm or more.

[0065] According to the studies of the present inventors, in STEM-HAADF images (basal plane images) from the

[001] incidence of composite tungsten oxide particles having a mass ratio (x / y) of M element to W element of greater than 0.37, band-shaped defects are observed. These band-shaped defects are planar defects of W atoms parallel to the c-axis. This phenomenon occurs because the number of M element atoms is in excess of the number of W atoms. Due to the excess M element atoms, in the process of rearrangement of W atoms, in addition to hexagonal crystals, heterophases such as pyrochlore phases are generated, and band-shaped W atom defects exceeding 10 nm in length also occur on the basal plane of the composite tungsten oxide particles. When W atom vacancy regions with lengths of 10 nm or more are formed, vacancy regions begin to form periodically, which is thought to stabilize heterophases such as pyrochlore phases. When the composite tungsten oxide particles of this embodiment are industrially synthesized, bias in the blending of the M element source and the W element source may occur in the raw material preparation process described below. In this case, the ratio of the amount of substance (x / y) of the M element to the W element may be greater than 0.37 in some of the obtained composite tungsten oxide particles, and some of the particles may have band-like W atom defects with a length of more than 10 nm on the basal surface. However, if the number ratio of particles with such defects is less than 20%, the infrared absorption properties will not be deteriorated. (4) Evaluation of composite tungsten oxide particles by XPS The W atoms of the composite tungsten oxide particles that absorb infrared rays are W atoms resulting from oxygen vacancies. ５＋ And, W ６＋ The intensity of the 4f orbital of the W atom in the XPS spectrum is expressed as W ６＋ and W ５＋ By separating the XPS spectrum, it can be confirmed that the composite tungsten oxide particles according to Example 1, which is an example of the composite tungsten oxide particles of the present embodiment, have a more advanced oxidation state than the composite tungsten oxide particles synthesized by the solid-phase method listed in Comparative Example 1.

[0066] 14A is a 4f profile of W atoms by XPS of the cesium tungsten composite oxide particles according to Example 1. Also, FIG. 14B is a 4f profile of W atoms by XPS of the cesium tungsten composite oxide particles according to Comparative Example 1.

[0067] In the hexagonal cesium tungsten composite oxide, W ６＋ is 4f in the binding energy range of 34 eV to 36 eV. ７／２ and 4f peaks in the binding energy range of 36 eV to 38 eV. ５／２ and a peak of W ５＋ is 4f in the binding energy range of 32 eV to 34 eV. ７／２ and 4f peaks in the binding energy range of 35 eV to 37 eV. ５／２ and a peak of

[0068] Based on this knowledge, W4f ７／２ and W4f ５／２ The peak spacing is fixed at 2.18 eV, the peak area ratio is fixed at 0.75, and a Gaussian or Lorentzian distribution is applied to the measured profile by the least squares method, thereby enabling XPS peak separation. ６＋ and W ５＋ W for the sum of the intensities ５＋ By knowing the ratio of the intensity of W4f, the oxidation state of the W atoms in the composite tungsten oxide particles can be determined. ７／２ and W4f ５／２ The half-widths of the spectra were matched.

[0069] The composite tungsten oxide particles according to Example 1 are ６＋ and W ５＋ W for total strength ５＋ The proportion of W in the composite tungsten oxide particles of Comparative Example 1 was 25.96%. ６＋ and W ５＋ The intensity separation shows that the composite tungsten oxide particles of Example 1, the profile of which is shown in FIG. 14A, have a higher W content than the composite tungsten oxide particles of Comparative Example 1, the profile of which is shown in FIG. 14B. ５＋ The proportion of W is small. ６＋ The higher the proportion of , the more oxidation has progressed.

[0070] In Example 1, W ５＋The reason why the amount of W atoms in the crystal is small and oxidation is advanced is presumably because the W atoms in the crystal are stabilized by bonding with oxygen due to the presence of W vacancies formed in the c-axis direction or the basal plane direction, as shown in Figures 7A and 7B or Figures 12A and 12B.

[0071] Although the above example is merely an example, as previously mentioned, the composite tungsten oxide particles of this embodiment can be produced by aerosolizing raw materials and then subjecting them to heat treatment, etc. Composite tungsten oxide particles produced by such a production method involving aerosolization of raw materials tend to be more oxidized than composite tungsten oxide particles synthesized by a conventional solid-phase method and obtained by pulverization, etc. (5) Peak Separation and Integrated Intensity of Localized Surface Plasmon Absorption and Polaron Absorption of Composite Tungsten Oxide Particles The oxidation state of the composite tungsten oxide particles of this embodiment affects their optical properties. The molar extinction coefficient curve was examined from the absorption curve of a dispersion of composite tungsten oxide particles measured by a spectrophotometer. The absorption in the absorption curve is caused by the localized surface plasmon absorption and polaron absorption of the particles, and the absorption curve is the result of the combination of these absorptions.

[0072] In the case of a composite tungsten oxide, the localized surface plasmon absorption exhibits anisotropy with respect to the c-axis. Specifically, in the case of a composite tungsten oxide particle, the localized surface plasmon absorption includes localized surface plasmon resonance absorption in a direction perpendicular to the c-axis (LSPR⊥) and localized surface plasmon resonance absorption in a direction parallel to the c-axis (LSPR / / ).

[0073] That is, in composite tungsten oxide particles, there are three absorption components: absorption due to localized surface plasmon resonance in a direction perpendicular to the c-axis (vertical direction) (LSPR⊥), absorption due to localized surface plasmon resonance in a direction parallel to the c-axis (parallel direction) (LSPR / / ), and polaron absorption. Therefore, the molar absorption coefficient curve of the composite tungsten oxide particles can be separated into three absorption curves.

[0074] Specifically, the wavelength on the horizontal axis of the molar absorption coefficient curve is converted to energy (eV), and the molar absorption coefficient curve is fitted with a Gaussian distribution and a Lorentzian distribution based on Mie scattering theory, and then the absorption curve is separated into an absorption curve due to localized surface plasmon resonance in a direction perpendicular to the c-axis (LSPR⊥), an absorption curve due to localized surface plasmon resonance in a direction parallel to the c-axis (LSPR / / ), and an absorption curve due to polaron absorption.

[0075] By separating the molar absorption coefficient curves, the absorption curve due to localized surface plasmon resonance in a direction perpendicular to the c-axis (LSPR⊥), the absorption curve due to localized surface plasmon resonance in a direction parallel to the c-axis (LSPR / / ), and the absorption curve due to polaron absorption can be obtained, thereby determining the average values ​​(peak energy (wavelength)) of the Gaussian distribution and Lorentzian distribution. Each Gaussian distribution is expressed by equation (1).

[0076] In formula (1), A represents the peak intensity, b represents the average value, E represents the energy, and c represents the standard deviation.

[0077] The Lorentz distribution is expressed by the following equation (2).

[0078] In equation (2), E is the energy, b is the average value, and d is a constant.

[0079] The absorption curves in the range of 0.5 eV to 2.0 eV (wavelengths of 620 nm to 2500 nm) were separated using these functions and the results are shown in Figures 15A and 15B. The near-infrared region (wavelengths of 780 nm to 2500 nm) is 0.5 eV to 1.59 eV.

[0080] Figure 15A shows the molar absorption coefficient curve of composite tungsten oxide particles according to Example 1, which is an example of the composite tungsten oxide particles of this embodiment. Figure 15B shows the molar absorption coefficient curve of composite tungsten oxide particles according to Comparative Example 1, which is an example of composite tungsten oxide particles synthesized by a conventional solid-phase method and obtained by pulverization. Table 2 shows the peak positions, peak intensities, and integrated intensities of the absorption curves of the three absorption elements. Furthermore, Table 3 shows the ratios of the integrated intensities of the absorption curves of the three absorption elements to the integrated intensity of the molar absorption coefficient curve.

[0081] 15A and 15B are merely examples, and the molar absorption coefficient curves in each figure are illustrative and are not limited to these molar absorption coefficient curves, but the composite tungsten oxide particles of the present embodiment exhibit a tendency similar to the molar absorption coefficient curve shown in FIG. 15A.

[0082] The absorption peak in the localized surface plasmon resonance (LSPR⊥) absorption curve in the direction perpendicular to the c-axis of the composite tungsten oxide particle according to Example 1 shown in FIG. 15A is 0.86 eV (wavelength 1435 nm), and the integrated intensity of the absorption curve is 96015.38 [L eV / (mol cm)].

[0083] In the molar absorption coefficient curve shown in FIG. 15A, the absorption peak in the absorption curve of localized surface plasmon resonance (LSPR / / ) in the direction parallel to the c-axis is 1.20 eV (wavelength 1030 nm), and the integrated intensity of the absorption curve is 33042.00 [L eV / (mol cm)].

[0084] In the molar absorption coefficient curve shown in FIG. 15A, the absorption peak in the polaron absorption curve is 1.26 eV (wavelength 985 nm), and the integrated intensity of the absorption curve is 12265.60 [L·eV / (mol·cm)].

[0085] 15A , the proportion of the integrated intensity of the polaron absorption curve is 8.7% of the integrated intensity of the three absorption curves. The composite tungsten oxide particles of Example 1 were synthesized by aerosolization followed by heat treatment or the like, and the integrated intensity of the polaron absorption was reduced compared to composite tungsten oxide particles synthesized by the conventional solid-phase method.

[0086] 15B shows the molar absorption coefficient curve of the composite tungsten oxide particles according to Comparative Example 1, which were synthesized by a conventional solid-phase method and then pulverized. In the molar absorption coefficient curve shown in FIG. 15B, the absorption peak in the localized surface plasmon resonance (LSPR⊥) absorption curve in the direction perpendicular to the c-axis is 0.80 eV (wavelength 1550 nm), and the integrated intensity of the absorption curve is 78,843.30 [L eV / (mol cm)].

[0087] In the molar absorption coefficient curve shown in FIG. 15B, the absorption peak in the absorption curve of localized surface plasmon resonance (LSPR / / ) in the direction parallel to the c-axis is 1.00 eV (wavelength 1240 nm), and the integrated intensity of the absorption curve is 20209.67 [L eV / (mol cm)].

[0088] In the molar absorption coefficient curve shown in FIG. 15B, the absorption peak in the polaron absorption curve is 1.40 eV (wavelength 885 nm), and the integrated intensity of the absorption curve is 31174.01 [L·eV / (mol·cm)].

[0089] Of the integrated intensities of the three absorption curves in the molar absorption coefficient curve shown in FIG. 15B, the proportion of the integrated intensity of the absorption curve of polaron absorption is 23.9%.

[0090] As is clear from the comparison of the proportions of integrated intensities of the polaron absorption curves above, the composite tungsten oxide particles of Example 1 have weaker polaron absorption than the composite tungsten oxide particles of Comparative Example 1. This is also shown by the fact that the peak value of the polaron absorption curve appearing at 1.26 eV (wavelength 985 nm) of the composite tungsten oxide particles of Example 1 is weaker than the peak value of the polaron absorption appearing at 1.40 eV (wavelength 885 nm) of the composite tungsten oxide synthesized by the solid-phase method.

[0091] Furthermore, the composite tungsten oxide particles of Example 1 have a higher ratio of integrated intensity of the absorption curves of LSPR⊥ and LSPR / / , which are absorptions due to localized surface plasmon resonance. In particular, the ratio of integrated intensity of the absorption curve of LSPR / / in the composite tungsten oxide particles of Example 1 is higher than the ratio of integrated intensity of the absorption curve of LSPR / / in the composite tungsten oxide particles of Comparative Example 1, which were synthesized by a solid-phase method and pulverized. These differences in absorption state are reflected in optical properties.

[0092] Here, the integrated intensity of each of the three absorption curves is the integrated intensity at 0.5 eV or more and 2.0 eV or less (wavelength 620 nm or more and 2500 nm or less). By comparing the integrated intensities of the three absorption components, i.e., localized surface plasmon resonance (LSPR⊥) in an orientation perpendicular to the c-axis, localized surface plasmon resonance (LSPR / / ) in an orientation parallel to the c-axis, and polaron absorption, within the above range, the contributions of the three absorption components in the near-infrared region (wavelength 780 nm or more and 2500 nm or less) can be determined.

[0093] Furthermore, absorption peaks appear in the following order from the low energy side: localized surface plasmon resonance perpendicular to the c-axis, localized material plasmon absorption parallel to the c-axis, and polaron absorption. In other words, absorption due to polarons appears in the high energy region (the short wavelength side of the near-infrared region).

[0094] The absorption by polarons in composite tungsten oxide particles is due to the W atoms in the crystals that make up the particles. ５＋ As shown in the above XPS results, the composite tungsten oxide particles of the present embodiment have W due to oxygen deficiency. ５＋Since the molar absorption coefficient curve is less than that of conventionally known composite tungsten oxide particles, when peak separation is performed, the proportion of polaron absorption is smaller than that of conventionally known composite tungsten oxide particles. In the composite tungsten oxide particles of this embodiment, the integrated intensity or peak value of the absorption curve of localized surface plasmon absorption in the direction parallel to the c-axis is higher than the integrated intensity or peak value of polaron absorption, resulting in rapid absorption of infrared light near a wavelength of 1000 nm. That is, the composite tungsten oxide particles of this embodiment have weak absorption of light near a wavelength of 800 nm due to polaron absorption, but are effective in absorbing infrared light near a wavelength of 1000 nm. In contrast, the composite tungsten oxide particles synthesized by the conventionally known solid-phase method have a higher integrated intensity or peak value of the absorption curve of polaron absorption than the integrated intensity or peak value of the absorption curve of localized surface plasmon absorption in the direction parallel to the c-axis, as shown in FIG. 15B . This difference appears in the color tone of transmitted light, and the composite tungsten oxide particles of this embodiment can make the transmitted light have a neutral color tone when made into a dispersion or a dispersion. Furthermore, the composite tungsten oxide particles of this embodiment can exhibit excellent properties in terms of visible light transmission performance and near-infrared shielding performance.

[0095] Furthermore, the molar absorption coefficient of the powder composed of composite tungsten oxide particles in the dispersion can be determined from the molar absorption coefficient curve. The molar absorption coefficient of the powder composed of the composite tungsten oxide particles of this embodiment is preferably 2600 L / (mol cm) or more, and more preferably 2800 L / (mol cm) or more.

[0096] By adjusting the manufacturing conditions of conventionally known composite tungsten oxide particles, the peak value of the absorption curve for polaron absorption can be made lower than the peak value of the absorption curve for localized surface plasmon absorption in the direction parallel to the c-axis.

[0097] However, when the peak value of the absorption curve of the polaron absorption is lower than the peak value of the absorption curve of the localized surface plasmon absorption in the direction parallel to the c-axis in a conventionally known composite tungsten oxide particle, the molar extinction coefficient becomes less than 2000 L / (mol cm). It is desirable for an infrared-absorbing material to have a high molar extinction coefficient, and a high molar extinction coefficient enables even a small amount of the infrared-absorbing material to exhibit an excellent infrared-shielding effect.

[0098] The composite tungsten oxide particles of the present embodiment can be composite tungsten oxide particles that have superior infrared absorption ability to the composite tungsten oxide particles exemplified in Comparative Example 1, which are obtained by synthesis using a conventionally known solid-phase method and pulverization, due to the crystal structure and electronic state of the composite tungsten oxide.

[0099] The composite tungsten oxide particles of this embodiment can impart infrared absorbing properties to the fibers by being disposed in one or more locations selected from the interior and surface of the fibers.

[0100] When the light transmission profile of a dispersion of the composite tungsten oxide particles of this embodiment dispersed in a solvent is measured using a spectrophotometer, the peak transmittance in the wavelength range of 500 nm to 600 nm can be 75% or more, and the bottom transmittance in the near-infrared region can be 5% or less. That is, the dispersion of the composite tungsten oxide particles of this embodiment has an excellent infrared shielding effect (infrared absorption effect). Therefore, the amount of composite tungsten oxide particles added to the infrared-absorbing fibers and textile products of this embodiment required to exhibit the function of preventing voyeurism by imaging devices such as CCD cameras can be reduced compared to when conventional composite tungsten oxide particles are used.

[0101] Furthermore, the dispersion of composite tungsten oxide particles of this embodiment can transmit red light with a wavelength of around 800 nm, compared to the dispersion of composite tungsten oxide particles shown in Comparative Example 1. This can also contribute to improving the color tone of infrared-absorbing fibers that use composite tungsten oxide particles. [Method for producing composite tungsten oxide particles] An outline of the method for producing composite tungsten oxide particles of this embodiment will be described.

[0102] According to the method for producing composite tungsten oxide particles of this embodiment, the composite tungsten oxide particles described above can be produced, so the matters already described will not be described again. Note that, here, only a configuration example of the method for producing composite tungsten oxide particles is shown, and the method for producing the composite tungsten oxide particles described above is not limited to the following configuration example.

[0103] The method for producing composite tungsten oxide particles of this embodiment is preferably a method that can directly synthesize composite tungsten oxide particles with a particle diameter of 1 μm or less. If composite tungsten oxide particles with a particle diameter of 1 μm or less can be directly synthesized, fine particles that are less affected by damage caused by pulverization or dispersion, for example, composite tungsten oxide particles with a particle diameter of 800 nm or less, can be obtained.

[0104] A preferred method for directly synthesizing composite tungsten oxide particles having a particle size of 1 μm or less is a production method in which the particles are synthesized through a heat treatment step in which an aerosol of raw materials containing an M element source and a tungsten element source is supplied to an electric furnace, flame, or plasma.

[0105] Therefore, the method for producing composite tungsten oxide particles of the present embodiment can include the following raw material preparation step, aerosol formation step, heat treatment step, and reduction treatment step.

[0106] In the raw material preparation step, a raw material containing an M element source and a tungsten element source can be prepared.

[0107] In the aerosol forming step, the raw material prepared in the raw material preparing step can be aerosolized.

[0108] In the heat treatment process, the aerosolized raw material can be heat treated in a reaction field.

[0109] In the reduction treatment step, the particles obtained in the heat treatment step can be reduced in an atmosphere containing a reducing gas. (1) Regarding Each Step Hereinafter, each step of the method for producing composite tungsten oxide particles of this embodiment will be described. (1-1) Raw Material Preparation Step In the raw material preparation step, a raw material containing an M element source and a tungsten element source (hereinafter also referred to as a "W element source") can be prepared.

[0110] In the raw material preparation step, the raw materials can be blended and prepared so that the ratio of the amount of substance of the M element to the amount of substance of the W element contained in the raw materials corresponds to the composition of the target composite tungsten oxide particles.

[0111] The state of the raw material prepared in the raw material preparation step is not particularly limited, and may be liquid or powder, and preferably can be formed into an aerosol by spraying, etc. Here, an aerosol refers to a mixture of minute liquid or solid particles suspended in a gas and the surrounding gas.

[0112] When the raw material is a liquid, the raw material can be prepared by preparing a solution containing, for example, an M element source and a W element source.

[0113] Alternatively, a solution containing an M element source and a solution containing a W element source may be prepared in advance, and the two solutions may be mixed in the raw material preparation step to form a raw material mixed solution.

[0114] The raw material may be supplied in the form of droplets to the heat treatment step described below. In this case, a raw material preparation step can be carried out by mixing a solution containing an M element source and a solution containing a W element source immediately before supplying the raw material to a droplet formation section (droplet formation means) that forms the droplets, or in the droplet formation section. Then, an aerosol formation step described below can be carried out in the droplet formation section.

[0115] For example, if premixing a solution containing an M element source with a solution containing a W element source poses problems such as gelation, it is preferable to prepare both solutions in advance as described above and mix them immediately before the aerosol formation step. When the raw material preparation step is performed immediately before the aerosol formation step, the ratio of the amounts of substance of the M element and the W element in the raw material can be adjusted to a desired range by adjusting the concentrations of both solutions and the speeds at which both solutions are sent to the droplet formation unit.

[0116] As described above, when the raw material preparation step is carried out immediately before the aerosol formation step, the aerosol formation step and the raw material preparation step do not need to be clearly separated, and both steps can be carried out continuously.

[0117] When the solution containing the M element source and the solution containing the W element source are mixed in the raw material preparation step as described above, the specific method for mixing is not particularly limited, and any method can be used.

[0118] The W element source is not particularly limited, and may be any raw material containing tungsten, such as simple tungsten or a tungsten compound. As the W element source, a tungsten salt or the like may be used, and for example, hexacarbonyl tungsten may be preferably used. Hexacarbonyl tungsten is, for example, W(CO) ６ As the solution containing the W element source, an organic solution containing the W element source can be preferably used because of ease of handling.

[0119] The M element source is not particularly limited, and may be any raw material containing the M element, such as the M element itself or a compound containing the M element. As a solution containing the M element source, for example, a solution of a salt containing the M element can be used. The type of salt of the M element that is the M element source is not particularly limited, and for example, one or more types selected from carbonates, acetates, nitrates, hydroxides, etc. of the M element can be used.

[0120] As the solution containing the M element source, an ethanol solution containing the M element source can be preferably used because of ease of handling.

[0121] For example, even when the M element is cesium, one or more salts selected from carbonates, acetates, nitrates, hydroxides, etc. can be used as the salt of the M element source, but acetate is particularly preferred because cesium acetate is particularly easily dissolved in ethanol.

[0122] The ratio of the M element to 1 mole of tungsten element in the obtained composite tungsten oxide, i.e., the doping amount, is determined by the ratio of the W element source to the M element source when forming the raw material mixed solution. Therefore, the doping amount can be controlled by, for example, the concentration of the solution containing the W element source or the concentration of the solution containing the M element source.

[0123] The concentration of the W element source contained in the solution containing the W element source, i.e., the concentration of the salt of the W element, is not particularly limited. For example, the tungsten concentration of the solution containing the W element source is preferably 0.001 mol / L or more and 10 mol / L or less, more preferably 0.01 mol / L or more and 10 mol / L or less, and even more preferably 0.01 mol / L or more and 1 mol / L or less. This is because, by making the tungsten concentration of the solution containing the W element source 0.001 mol / L or more, the production amount of composite tungsten oxide particles per unit time can be sufficiently ensured, and for example, a sufficient amount can be recovered using a filter, etc., thereby improving productivity. Furthermore, by making the tungsten concentration of the solution containing the W element source 10 mol / L or less, the reprecipitation of the dissolved W element source can be suppressed, the generated particles can be suppressed from agglomerating, and for example, the inclusion of coarse composite tungsten oxide particles having a particle diameter of more than 1 μm can be suppressed. Furthermore, additives such as agents for adjusting pH and surfactants can be added to the solution containing the W element source.

[0124] Furthermore, the concentration of the M element source contained in the solution containing the M element source is not particularly limited, and can be selected depending on the desired composition of the composite tungsten oxide particles to be produced, the concentration of the W element source contained in the solution containing the W element source, and the like.

[0125] Any component other than the solution containing the W element source and the solution containing the M element source can be added to the raw material mixture solution.

[0126] Up to this point, the case where the raw material is a liquid has been described as an example, but the raw material may also be solid, for example, powder. When the raw material is a powder, it can be prepared by, for example, mixing a powder of an M element compound with a powder of a tungsten compound. Furthermore, for example, a precursor powder obtained by adding a tungsten compound powder to a solution containing an M element source and stirring, and then removing the solvent by drying or the like, can be used as the raw material.

[0127] When the raw material is a solid, the W element source is not particularly limited, and tungsten salts or the like can be used. For example, H ２ WO ４and ammonium paratungstate can be preferably used.

[0128] H ２ WO ４ The elements other than tungsten are H (hydrogen) and O (oxygen), and the elements other than tungsten are discharged to the outside of the system in the heat treatment process described later. ２ WO ４ can be preferably used because it is possible to obtain composite tungsten oxide particles in which the inclusion of impurities is suppressed.

[0129] The M element source can be, for example, a powder of a salt containing the M element. The type of salt containing the M element is not particularly limited, but one or more types selected from carbonates, acetates, nitrates, hydroxides, etc. of the M element can be used.

[0130] For example, when the M element is cesium, one or more selected from carbonates, acetates, nitrates, hydroxides, etc. can be used, with carbonates being particularly preferred. (1-2) Aerosol Formation Step In the method for producing composite tungsten oxide particles of this embodiment, it is preferable to supply the raw material prepared in the raw material preparation step in the form of an aerosol to the heat treatment step. Specifically, it is preferable to transport the aerosol using a carrier gas such as oxygen and subject it to the heat treatment step.

[0131] Therefore, the method for producing composite tungsten oxide particles of the present embodiment can also include an aerosol formation step in which the raw material is converted into an aerosol containing droplets or particles of the raw material.

[0132] The means and method for forming the aerosol in the aerosol forming step are not particularly limited, and can be selected depending on the state of the raw material, etc.

[0133] When the raw material is a liquid, an aerosol can be formed by spraying the liquid toward a carrier gas using various atomizers such as a centrifugal atomizer or a two-fluid nozzle. Alternatively, droplets can be formed by irradiating the liquid with ultrasound.

[0134] When the raw material is a powder, an aerosol can be formed by a device that disperses the raw material powder and supplies the powder into an airflow. For example, the aerosol can be formed by an aerosol forming device that includes a stirring unit such as a rotating brush or stirring blade, and a powder supply unit that includes a piston or screw feeder that delivers the raw material to the stirring unit. The raw material powder supplied from the powder supply unit is dispersed into particles that make up the powder in the stirring unit, and an aerosol can be generated from the raw material powder by sending each particle into a carrier gas. The stirring unit allows the rotation speed of the brush or stirring blade to be selected so that the raw material powder can be dispersed into particles, and it is preferable to rotate it at high speed.

[0135] When forming droplets dispersed in a gas in the aerosol forming process, the size of the formed droplets is not particularly limited, but the diameter of the droplets is preferably 100 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. By setting the diameter of the droplets to 100 μm or less, it is possible to prevent the obtained composite tungsten oxide particles from becoming coarse, and it is possible to obtain composite tungsten oxide particles on the order of nanometers. Note that the lower limit of the size of the droplets formed in the aerosol forming process is not particularly limited. However, since it is difficult to form excessively small droplets and there is a risk of reduced productivity, it is preferable that the droplet size be, for example, 1 μm or more.

[0136] When forming solid particles dispersed in a gas in the aerosol formation process, the particle size is not particularly limited, but the particle diameter is preferably 100 μm or less, more preferably 10 μm or less, and even more preferably 3 μm or less. By setting the particle diameter to 100 μm or less, it is possible to more reliably perform heat treatment to the inside of the particles. The particle diameter can be measured in the same manner as the particle size of the composite tungsten oxide particles described above. (1-3) Heat Treatment Process In the heat treatment process, the raw material is heat-treated to process the raw material into composite tungsten oxide particles. The heat treatment only needs to be performed at a temperature of 500°C or higher, and the configuration of the heat source is not particularly limited. Therefore, the heat treatment process can be performed by using a carrier gas to introduce the raw material into a flame, a tubular electric furnace, or a plasma. Whether a flame, an electric furnace, or plasma is used, the heat treatment temperature can be 500°C or higher. By carrying out the heat treatment at 500° C. or higher, the compounds contained in the raw material are decomposed, and tungsten reacts with the M element to form a composite tungsten oxide.

[0137] By containing appropriate W atom deficiencies and heterogeneous phases in the composite tungsten oxide particles obtained after the heat treatment process, composite tungsten oxide particles containing dark areas due to the Z contrast of W atoms can be obtained after the reduction treatment process. Therefore, conditions such as the heat treatment temperature can be selected so that appropriate W atom deficiencies and heterogeneous phases are generated in the composite tungsten oxide particles obtained after the heat treatment process, and composite tungsten oxide particles in which spots with reduced W atom Z contrast are confirmed after the reduction treatment process are produced. For this reason, it is preferable to conduct a preliminary test or the like and select the raw material supply rate, heat treatment temperature, etc. in the heat treatment process so that the desired proportion of dark areas in the Z contrast of W atoms is contained after the reduction treatment process. Note that it is preferable to select conditions such as the heat treatment temperature so that heterogeneous phases can be reduced or removed after the reduction treatment process.

[0138] The heat treatment temperature is sufficient as long as it can promote the reaction between tungsten and the element M, and therefore may be 500° C. or higher, preferably 550° C. or higher, and more preferably 1000° C. or higher. There is no particular upper limit to the heat treatment temperature, but from the viewpoint of suppressing energy consumption, it is preferably 4000° C. or lower.

[0139] In the heat treatment step, a flame can be used as described above, and the raw material can be heat-treated using the flame. By using a flame in the heat treatment step and adjusting the temperature of the flame reaction field, the particle size of the resulting composite tungsten oxide particles can be selected.

[0140] When a liquid raw material is atomized into a carrier gas to form droplets, and the droplets are introduced into a flame to synthesize composite tungsten oxide particles, the droplets of the raw material are transported through the flame by a carrier gas such as oxygen gas. When the droplets of the raw material are transported into the flame, the organic solvent containing the raw material tungsten source and M element source burns, and the solvent is decomposed by the combustion reaction. The heat generated by the combustion reaction contributes to the decomposition reaction of tungsten and M element, which precipitate during the cooling process in the tail flame of the flame field.

[0141] For example, as mentioned above, the W element source may be tungsten hexacarbonyl, and the M element source may be cesium acetate if the M element is cesium. These salts decompose in the heat treatment process. At this time, W is converted into WO ６ On the other hand, Cs does not easily form oxides as a monomer, and some of it passes through the filter and is discharged to the outside of the system without being able to precipitate as nano-sized powder.

[0142] In the above case, tungsten reacts with the M element during the decomposition process of the solute portion to form a composite tungsten oxide.

[0143] When a flame is used in the heat treatment process, the conditions for forming the flame are not particularly limited, but the flame can be formed using, for example, a mixed gas containing oxygen and a hydrocarbon. By forming a flame using a mixed gas containing oxygen and a hydrocarbon, a flame with a stable temperature can be formed, and composite tungsten oxide particles can be produced with reduced variation in particle size, etc.

[0144] The method for adjusting the flame size and temperature is not particularly limited, but it is preferable to adjust the flow rates of the oxygen and flammable gases such as hydrocarbons in the gas mixture supplied to the flame, while maintaining a flow rate ratio that allows the flammable gas to burn. This is because it is possible to adjust the heat power while ensuring the amount of oxygen necessary for the flammable gas to burn.

[0145] For example, when a flame is formed using a gas mixture containing oxygen and propane, the volumetric ratio of the flow rates of propane and oxygen in the gas mixture is preferably 5 to 8 oxygen parts per 1 part of propane, and the flow rate of propane is preferably in the range of 0.5 to 2 L / min. This is because, when the flow rate of propane is 1, by setting the flow rate of oxygen to 5 or more, combustion of propane, which is a flammable gas, can be sufficiently promoted. However, it is preferable to supply 8 or less oxygen parts per 1 part of propane to avoid excessive oxygen supply.

[0146] The heat treatment temperature in the flame reaction field, etc. also affects the particle size of the resulting composite tungsten oxide particles.

[0147] This is presumably because thermal energy in a reaction field such as a flame is used to sublimate the generated composite tungsten oxide particles, causing the particles to burst upon sublimation, resulting in particles with a fine particle size.

[0148] The composite tungsten oxide particles obtained by the heat treatment can be recovered, for example, using a filter. (1-4) Reduction Treatment Step Particles obtained through the heat treatment step, specifically composite tungsten oxide particles, may not exhibit infrared absorption properties. Therefore, the inventors of the present invention conducted studies and found that by further performing a reduction treatment step in which the composite tungsten oxide particles obtained through the heat treatment step are subjected to a reduction treatment, the composite tungsten oxide particles can exhibit infrared absorption properties.

[0149] Therefore, the method for producing composite tungsten oxide particles of this embodiment can also have a reduction treatment step in which the particles obtained in the heat treatment step are reduced in an atmosphere containing a reducing gas. Specifically, for example, the method for producing composite tungsten oxide particles of this embodiment can have a reduction treatment step in which the particles obtained in the heat treatment step are reduced in an atmosphere containing a reducing gas at a temperature in the range of more than 400°C and less than 700°C after the heat treatment step.

[0150] Although the conditions for the reduction treatment are not particularly limited, it is preferable to select the conditions for the reduction treatment so that, when the composite tungsten oxide particles after the reduction treatment are analyzed by X-ray diffraction pattern, the crystal structure does not change before and after the reduction treatment step, and metallic tungsten etc. does not precipitate. In addition, it is preferable to also select the conditions for the reduction treatment so that the composite tungsten oxide particles after the reduction treatment step contain dark areas in the Z contrast of W atoms at a desired ratio.

[0151] In the reduction treatment step, the composite tungsten oxide particles obtained in the heat treatment step can be reduced by raising and lowering the temperature in a reducing atmosphere containing a reducing gas, that is, by performing heat treatment.

[0152] During the reduction treatment step, the composite tungsten oxide particles may be stirred or left to stand, and the handling of the composite tungsten oxide particles during the reduction treatment step can be selected appropriately, but it is preferable to select handling conditions so as not to cause precipitation of metallic tungsten.

[0153] The temperature of the reduction treatment (reduction treatment temperature) is preferably higher than 400°C, more preferably 450°C or higher, and even more preferably 500°C or higher.

[0154] The upper limit of the temperature of the reduction treatment is not particularly limited, but is preferably less than 700°C, more preferably 650°C or less, and even more preferably less than 650°C.

[0155] In addition, when the raw material is a liquid, the particle size obtained in the aerosol formation step decreases when the raw material concentration is reduced. Since the particles with a smaller diameter are easier to reduce, the temperature in the reduction treatment step can be lowered. In the reduction treatment step, the temperature can be raised from room temperature to the reduction treatment temperature and then lowered back to room temperature.

[0156] The reduction conditions can be determined based on the optical properties of the resulting composite tungsten oxide particles.

[0157] By setting the reduction temperature to above 400° C., the reduction process of the composite tungsten oxide particles can be advanced, and the infrared absorption properties can be more reliably exhibited. Furthermore, by setting the temperature to below 700° C., the reduction of the composite tungsten oxide particles to metallic tungsten can be suppressed.

[0158] The reducing atmosphere is a mixture of an inert gas such as argon and H ２ It is preferable to use a mixed gas atmosphere with a reducing gas such as H ２ Gas is preferred.

[0159] H as a reducing gas ２ When gas is used, H in a reducing atmosphere ２ The gas content can be appropriately selected. ２ The gas content is preferably in the range of 0.1% to 10% by volume, more preferably 2% to 10% by volume. Care must be taken when reduction is carried out in an atmosphere containing only a reducing gas, as this may cause the reduction reaction to proceed excessively, resulting in the precipitation of metallic tungsten.

[0160] The reduction treatment time is preferably 30 minutes or more, including the total time from temperature increase to temperature decrease. There is no particular upper limit to the reduction treatment time, and it is preferable to select it by conducting a preliminary test or the like so that the reduction does not proceed excessively. Here, the total time from temperature increase to temperature decrease means the time from starting temperature increase from room temperature, reaching the reduction treatment temperature, and cooling to room temperature. It is preferable that the composite tungsten oxide particles are placed in the reducing atmosphere described above during this time.

[0161] By carrying out the reduction treatment step in this way, it is possible to convert the undesired heterogeneous phase in the composite tungsten oxide particles obtained after the heat treatment step into the desired composite tungsten oxide phase. (2) Apparatus that can be suitably used in the method for producing composite tungsten oxide particles (2-1) Composite material production apparatus An example of the configuration of a composite material production apparatus that can be suitably used in the method for producing composite tungsten oxide particles of this embodiment will be described below.

[0162] FIG. 1 is a diagram schematically illustrating a composite material manufacturing apparatus 10 according to the present embodiment.

[0163] The composite material manufacturing apparatus 10 has a storage section 11 containing a raw material solution, a two-fluid nozzle 12 that forms droplets of the raw material and also forms a flame, and a reaction tube 13 connected to a filter 14 that collects the formed composite tungsten oxide particles. As already explained, the raw material solution can be a solution containing an M element source and a W element source.

[0164] A raw material solution and a carrier gas are supplied to the two-fluid nozzle 12 to form an aerosol (aerosol formation process). For example, oxygen and a hydrocarbon are supplied to the two-fluid nozzle 12, forming a flame reaction field. The formed aerosol can be supplied into the flame and subjected to heat treatment (heat treatment process). A cooling water pipe 131 is arranged around the reaction tube 13, and cooling water is circulated through the pipe. The composite tungsten oxide particles introduced into the reaction tube 13 are collected by a filter 14, such as a bag filter.

[0165] In addition, an ejector 15 may be provided at the most downstream side to adjust the supply amount of carrier gas.

[0166] Here, an example of the configuration of a composite material apparatus in which droplets of raw material are formed and heat-treated using a flame to form composite tungsten oxide particles is shown, but the present invention is not limited to this configuration, and the raw material may be a powder or the like, and the heat source used for the heat treatment may be an electric furnace, etc. (2-2) Reduction Treatment Apparatus The reduction treatment apparatus can carry out the reduction treatment step described above.

[0167] The reduction treatment device is not particularly limited as long as it is configured to be able to carry out the reduction treatment step described above. For example, it may include a container for storing the composite tungsten oxide particles obtained by the composite material production device described above, a gas pipe for supplying a mixed gas that forms a reducing atmosphere into the container, and a heat source for heating the container.

[0168] Alternatively, a mixed gas that forms a reducing atmosphere may be introduced into the container and then exhausted, and the composite tungsten oxide particles to be treated may be placed under a gas flow of the mixed gas. In this case, a gas supply pipe and an exhaust pipe may be provided as gas pipes so that such a gas flow can be formed.

[0169] Furthermore, a stirring blade or the like may be used in combination to stir the composite tungsten oxide particles in the container.

[0170] FIG. 2 is a diagram showing a schematic configuration example of a reduction treatment device, and shows a cross section taken along a plane passing through the central axis of a reaction tube 21 of a reduction treatment device 20.

[0171] The reduction treatment device 20 is a horizontal tubular furnace, and can be used by attaching a gas inlet pipe (not shown) to one opening 21A of the reaction tube 21 and a gas exhaust pipe (not shown) to the other opening 21B of the tubular furnace. Then, by supplying a mixed gas that forms a reducing atmosphere from the opening 21A side, the inside of the reaction tube 21 can be made into a reducing atmosphere.

[0172] A heater 22 can be provided around the reaction tube 21, and the composite tungsten oxide particles can be placed in a ceramic container 23 such as a boat and placed at a position corresponding to the heater 22 inside the reaction tube 21 of the tubular furnace.

[0173] Using this reduction treatment device 20, the inside of the reaction tube 21 is made into a reducing atmosphere, and heating is performed to a desired temperature by the heater 22, thereby performing a reduction treatment on the composite tungsten oxide particles 24 placed in the container 23. [Infrared absorbing particle dispersion] Next, a description will be given of one example of the configuration of the infrared absorbing particle dispersion that can be used when producing the infrared absorbing fiber of this embodiment.

[0174] The infrared absorbing particle dispersion of this embodiment can contain infrared absorbing particles and a liquid medium. The infrared absorbing particles can be the above-mentioned composite tungsten oxide particles.

[0175] The liquid medium may be one or more selected from the group consisting of water, organic solvents, oils and fats, liquid resins, and liquid plasticizers. That is, as shown in Fig. 3, an infrared absorbing particle dispersion 30 of this embodiment may contain infrared absorbing particles 31 and a liquid medium 32. The infrared absorbing particle dispersion preferably has a configuration in which infrared absorbing particles are dispersed in a liquid medium.

[0176] 3 is a schematic diagram, and the infrared absorbing particle dispersion liquid of this embodiment is not limited to this form. For example, in FIG. 3, the infrared absorbing particles 31 are represented by circles and depicted as spherical particles, but the shape of the infrared absorbing particles 31, which are the composite tungsten oxide particles described above, is not limited to this form and can have any shape. The infrared absorbing particles 31 may, for example, have a coating on their surfaces. The infrared absorbing particle dispersion liquid 30 may contain other additives as needed in addition to the infrared absorbing particles 31 and the liquid medium 32.

[0177] As the liquid medium, as described above, one or more selected from water, organic solvents, oils and fats, liquid resins, and liquid plasticizers can be used.

[0178] As the organic solvent, various types can be selected, such as alcohols, ketones, esters, hydrocarbons, and glycols. Specific examples of the solvent include one or more selected from alcohol solvents such as isopropyl alcohol, methanol, ethanol, 1-propyl alcohol, butanol, pentanol, benzyl alcohol, diacetone alcohol, and 1-methoxy-2-propyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, methylpropyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ester solvents such as 3-methyl-methoxypropyl ether and n-butyl acetate; glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate; amides such as formamide, N-methylformamide, dimethylformamide, dimethylacetamide, and N-methyl-2-propylidone; aromatic hydrocarbons such as toluene and xylene; and halogenated hydrocarbons such as ethylene chloride and chlorobenzene. However, among these, organic solvents with low polarity are preferred, and in particular, isopropyl alcohol, ethanol, 1-methoxy-2-propyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, n-butyl acetate, etc. These organic solvents can be used alone or in combination of two or more.

[0179] Examples of fats and oils that can be used include one or more selected from drying oils such as linseed oil, sunflower oil, and tung oil; semi-drying oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil, and rice bran oil; non-drying oils such as olive oil, coconut oil, palm oil, and dehydrated castor oil; fatty acid monoesters obtained by directly esterifying fatty acids of vegetable oils with monoalcohols; ethers; and petroleum solvents such as Isopar (registered trademark) E, Exxor (registered trademark) Hexane, Heptane, E, D30, D40, D60, D80, D95, D110, and D130 (all manufactured by ExxonMobil).

[0180] As the liquid resin, for example, one or more types selected from liquid acrylic resin, liquid epoxy resin, liquid polyester resin, liquid urethane resin, etc. can be used.

[0181] As the liquid plasticizer, for example, a liquid plasticizer for plastics can be used.

[0182] The components contained in the infrared absorbing particle dispersion are not limited to the infrared absorbing particles and the liquid medium described above. The infrared absorbing particle dispersion may further contain any optional components added thereto, as necessary.

[0183] For example, an acid or alkali may be added to the infrared absorbing particle dispersion liquid as needed to adjust the pH of the dispersion liquid.

[0184] In addition, in order to further improve the dispersion stability of the infrared absorbing particles in the above-described infrared absorbing particle dispersion and to prevent the dispersed particle size from becoming coarse due to re-aggregation, various surfactants, coupling agents, and the like may be added to the infrared absorbing particle dispersion as dispersants.

[0185] The dispersant, such as the surfactant or coupling agent, can be selected depending on the application, but it is preferable that the dispersant has one or more functional groups selected from an amino group, a hydroxyl group, a carboxyl group, and an epoxy group. These functional groups adsorb to the surface of the infrared-absorbing particles to prevent aggregation and have the effect of uniformly dispersing the infrared-absorbing particles even in an infrared-shielding film formed using the infrared-absorbing particles. It is more preferable that the dispersant is a polymeric dispersant having one or more functional groups selected from the above functional groups (functional groups) in the molecule.

[0186] Suitable commercially available dispersants include Solsperse (registered trademark) 9000, 12000, 17000, 20000, 21000, 24000, 26000, 27000, 28000, 32000, 35100, 54000, and 250 (manufactured by Lubrizol Japan Co., Ltd.), and EFKA (registered trademark). 4008, 4009, 4010, 4015, 4046, 4047, 4060, 4080, 7462, 4020, 4050, 4055, 4400, 4401, 4402, 4403, 4300, 4320, 4330, 4340, 6220, 6225, 6700, 6780, 6782, 8503 (manufactured by Fuka Additives), Ajisper (registered trademark) PA111, PB821, PB822, PN411, Famex L-12 (manufactured by Ajinomoto Fine-Techno Co., Ltd.), DisperBYK (registered trademark) 101, 102, 106, 108, 111, 116, 130, 140, 142, 145, 161, 162, 163, 164, 166, 167, 168, 170, 171, 174, 180, 182, 192, 193, 2000, 2001, 2020, 2025, 2050, 2070, 2155, 2164, 220S, 300, 306, 320, 322, 325, 330, 340, 350, 377, 378, 380N, 410, 425, 430 (manufactured by Pick Chemie Japan Co., Ltd.), Dispaton (registered trademark) 1751N, 1831, 1850, 1860, 1934, DA-400N, DA-703-50, DA-725, DA-705, DA-7301, DN-900, NS-5210, NVI-8514L (manufactured by Kusumoto Chemicals Co., Ltd.), Arfon (registered trademark) UC-3000, UF-5022, UG-4010, UG-4035, UG-4070 (manufactured by Toagosei Co., Ltd.), and the like.

[0187] The method for dispersing the infrared absorbing particles in the liquid medium is not particularly limited as long as it can disperse the infrared absorbing particles in the liquid medium. In this case, it is preferable that the infrared absorbing particles can be dispersed so that the average particle size is 800 nm or less, and more preferably 1 nm or more and 800 nm or less.

[0188] Examples of methods for dispersing infrared-absorbing particles in a liquid medium include dispersion methods using devices such as a bead mill, a ball mill, a sand mill, a paint shaker, and an ultrasonic homogenizer. Among these, pulverization and dispersion using a media agitation mill such as a bead mill, a ball mill, a sand mill, or a paint shaker that uses a medium media (beads, balls, Ottawa sand) is preferred from the viewpoint of shortening the time required to achieve a desired average particle size. By the pulverization-dispersion treatment using a media agitation mill, not only is the infrared-absorbing particles dispersed in the liquid medium, but also microparticulation due to collisions between the infrared-absorbing particles and between the media and the infrared-absorbing particles progresses, allowing the infrared-absorbing particles to be dispersed in a more microparticulate form. In other words, the pulverization-dispersion treatment is performed.

[0189] The average particle size of the infrared absorbing particles is preferably 1 nm or more and 800 nm or less, as described above. This is because a small average particle size can suppress light scattering, thereby suppressing unintended gloss in the visible light region and the occurrence of unintended color tones due to light scattering whose intensity is wavelength-dependent (Rayleigh scattering).

[0190] Furthermore, if coarse particles are present in the process of kneading the composite tungsten oxide particles of this embodiment into fibers, the yarn may be broken during spinning. From this perspective, it is preferable to reduce the particle size of the composite tungsten oxide particles.

[0191] Therefore, the average particle size of the infrared absorbing particles is preferably 800 nm or less, more preferably 200 nm or less, even more preferably 100 nm or less, and particularly preferably 30 nm or less. The lower limit of the average particle size of the infrared absorbing particles is not particularly limited, but is, for example, preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more.

[0192] For the above reasons, the average particle size of the infrared absorbing particles is preferably 1 nm or more and 800 nm or less, more preferably 5 nm or more and 200 nm or less, still more preferably 10 nm or more and 200 nm or less, even more preferably 10 nm or more and 100 nm or less, and particularly preferably 10 nm or more and 30 nm or less.

[0193] The dispersed state of the infrared absorbing particles in the infrared absorbing fiber obtained using the infrared absorbing particle dispersion of this embodiment will not result in aggregation of particles having a particle size greater than the average particle size of the infrared absorbing particles in the dispersion, as long as the particles are added to the fiber using a known method.

[0194] The content of the infrared absorbing particles in the infrared absorbing particle dispersion liquid of this embodiment is not particularly limited, but is preferably, for example, 0.01% by mass or more and 80% by mass or less. This is because a sufficient solar radiation transmittance can be exhibited, that is, the solar radiation transmittance can be sufficiently suppressed, by setting the content of the infrared absorbing particles to 0.01% by mass or more. Also, by setting the content to 80% by mass or less, the infrared absorbing particles can be uniformly dispersed in the dispersion medium.

[0195] The infrared absorbing particle dispersion of this embodiment contains the composite tungsten oxide particles described above, and therefore can be an infrared absorbing particle dispersion that has excellent visible light transmittance and infrared shielding performance. Furthermore, the infrared absorbing particle dispersion of this embodiment has an excellent infrared shielding effect, in that even if the peak transmittance in the wavelength range of 500 nm to 600 nm is 75% or more, the bottom transmittance in the infrared range can be 5% or less. Furthermore, the infrared absorbing particle dispersion of this embodiment can achieve a transmittance of 50% or more at a wavelength of 700 nm and a transmittance of 30% or more at a wavelength of 800 nm. [Infrared absorbing fiber] The infrared absorbing fiber according to the present invention will be described.

[0196] Fig. 4 shows a schematic diagram of the infrared absorbing fiber of this embodiment. Fig. 4 shows a schematic cross-sectional view of an infrared absorbing fiber 40 taken along a plane passing through a central axis CA of a fiber 41. As shown in Fig. 4, the infrared absorbing fiber 40 of this embodiment can include fibers 41 and composite tungsten oxide particles 42.

[0197] The arrangement of the composite tungsten oxide particles 42 is not particularly limited, and the composite tungsten oxide particles 42 can be arranged, for example, at one or more locations selected from the surface 41A and the interior 41B of the fiber 41. Note that FIG. 4 is a schematic diagram showing an example in which the composite tungsten oxide particles 42 are arranged on both the surface 41A and the interior 41B of the fiber 41, but this is not a limitation. The composite tungsten oxide particles 42 may be arranged on only one of the surface 41A and the interior 41B of the fiber 41. Furthermore, while FIG. 4 depicts the composite tungsten oxide particles 42 as spherical particles, the shape of the composite tungsten oxide particles 42 is not limited to this shape and can have any shape.

[0198] The components contained in the infrared-absorbing fiber of this embodiment will be described below. (1) Components Contained in the Infrared-Absorbing Fiber (1-1) Fiber (1-1-1) Types of Fiber The fibers contained in the infrared-absorbing fiber of this embodiment can be selected from a variety of types depending on the application, and are not particularly limited. For example, the fibers can be one or more types selected from a fiber group consisting of synthetic fibers, semi-synthetic fibers, natural fibers, regenerated fibers, and inorganic fibers, and mixed yarns obtained by blending, doubling, or mixing two or more types of fibers selected from the above fiber group. In other words, fibers selected from the above fiber group can be used, or fibers selected from the above mixed yarns can be used.

[0199] In particular, in consideration of the ease with which the infrared absorbing particles can be incorporated into the interior of the fibers and the durability of heat retention, the fibers preferably contain synthetic fibers, and more preferably are made of synthetic fibers.

[0200] Each fiber will be described below. (Synthetic Fiber) The synthetic fiber is not particularly limited, but for example, one or more types selected from polyurethane fibers, polyamide fibers, acrylic fibers, polyester fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, polyether ester fibers, etc. can be used.

[0201] Examples of polyamide fibers include nylon, nylon 6, nylon 66, nylon 11, nylon 610, nylon 612, aromatic nylon, and aramid.

[0202] Examples of acrylic fibers include polyacrylonitrile, acrylonitrile-vinyl chloride copolymer, and modacrylic.

[0203] Examples of polyester fibers include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene naphthalate.

[0204] Examples of polyolefin fibers include polyethylene, polypropylene, and polystyrene.

[0205] Examples of polyvinyl alcohol fibers include vinylon.

[0206] Examples of polyvinylidene chloride fibers include vinylidene.

[0207] Examples of polyvinyl chloride fibers include polyvinyl chloride.

[0208] Examples of polyetherester fibers include Rexe, Success, etc. (Semi-synthetic fibers) As the semi-synthetic fibers, for example, one or more types selected from cellulose-based fibers, protein-based fibers, chlorinated rubber, hydrochloric rubber, etc. can be used.

[0209] Examples of cellulosic fibers include acetate, triacetate, and acetate oxide.

[0210] An example of the protein-based fiber is Promix, etc. (Natural Fiber) As the natural fiber, for example, one or more types selected from plant fibers, animal fibers, mineral fibers, etc. can be used.

[0211] Examples of plant fibers include cotton, kapok, flax, hemp, jute, Manila hemp, sisal, New Zealand hemp, ramie, palm, rush, and wheat straw.

[0212] Examples of animal fibers include wool such as sheep's wool, goat's hair, mohair, cashmere, alpaca, angora, camel, and vicuna, as well as silk, down, and feathers.

[0213] Examples of mineral fibers include asbestos, etc. (Recycled Fiber) As the recycled fiber, for example, one or more types selected from cellulose-based fibers, protein-based fibers, alginate fibers, rubber fibers, chitin fibers, mannan fibers, etc. can be used.

[0214] Examples of cellulosic fibers include rayon, viscose rayon, cupro, polynosic, and cuprammonium rayon.

[0215] Examples of protein fibers include casein fiber, peanut protein fiber, corn protein fiber, soy protein fiber, regenerated silk, etc. (Inorganic Fibers) As inorganic fibers, for example, one or more types selected from metal fibers, carbon fibers, silicate fibers, etc. can be used.

[0216] Examples of the metal fibers include metal fibers, gold threads, silver threads, and heat-resistant alloy fibers.

[0217] Examples of silicate fibers include glass fibers, slag fibers, rock fibers, etc. (1-1-2) Fiber Shape The cross-sectional shape of the fiber is not particularly limited, and examples thereof include one or more types selected from circular, triangular, hollow, flat, Y-shaped, star-shaped, core-sheath type, etc.

[0218] The inclusion and arrangement of composite tungsten oxide particles in the fiber are not particularly limited. For example, when the cross-sectional shape of the fiber is a core-sheath type, the composite tungsten oxide particles may be contained in the core or sheath of the fiber. Furthermore, the shape of the fiber is not particularly limited, and may be a filament (long fiber) or a staple (short fiber). (1-2) Composite Tungsten Oxide Particles Since the composite tungsten oxide particles have already been described, a detailed description will be omitted.

[0219] The content of the composite tungsten oxide particles in the infrared absorbing fiber of this embodiment is not particularly limited and can be selected depending on the properties required of the infrared absorbing fiber, etc. The composite tungsten oxide particles have a very high infrared absorption capacity per unit weight, so that they can exert their effects at a usage amount of about one-fourth to one-tenth of that of ITO or ATO.

[0220] The infrared absorbing fiber of this embodiment can contain the composite tungsten oxide particles in a proportion of 0.001% by mass or more and 80% by mass or less of the solid content of the fiber. Furthermore, when taking into consideration the weight of the fiber after the addition of the composite tungsten oxide particles and the raw material cost, it is more preferable that the infrared absorbing fiber of this embodiment contains the composite tungsten oxide particles in a proportion of 0.005% by mass or more and 50% by mass or less.

[0221] By including composite tungsten oxide particles in an infrared-absorbing fiber at a ratio of 0.001% by mass or more relative to the solid content of the fiber, sufficient infrared absorption can be achieved even when the fabric containing the composite tungsten oxide particles is thin. Furthermore, by including composite tungsten oxide particles in an amount of 80% by mass or less relative to the solid content of the fiber, deterioration of spinnability due to filter clogging, thread breakage, etc. can be more reliably avoided when spinning the infrared-absorbing fiber. Furthermore, by setting the composite tungsten oxide particle content to 80% by mass or less, deterioration of the physical properties of the fiber can be more reliably avoided. (1-3) Additives and Far-Infrared Emitting Substances The infrared-absorbing fiber of this embodiment can be composed only of the fiber and composite tungsten oxide particles, but can also contain optional components, such as far-infrared emitting substances and additives described below, depending on the purpose. (Additives) The infrared-absorbing fiber of this embodiment can also contain antioxidants, flame retardants, deodorizers, insect repellents, antibacterial agents, ultraviolet absorbers, etc., depending on the purpose, as long as the performance of the fiber is not impaired. (Far-infrared emitting material) The far-infrared emitting material is a material capable of emitting far-infrared rays, and is preferably in particulate form. That is, far-infrared emitting material particles can be suitably used as the far-infrared emitting material.

[0222] The far-infrared emitting material can be disposed at one or more locations selected from the surface and the interior of the fiber.

[0223] Examples of far-infrared emitting materials include ZrO ２ , SiO ２ , TiO ２ , Al ２ O ３ , MnO ２ , MgO, Fe ２ O ３ , metal oxides such as CuO, carbides such as ZrC, SiC, TiC, ZrN, Si ３ N ４ , nitrides such as AlN, and the like.

[0224] An example of a composite tungsten oxide particle is a particle containing cesium tungsten oxide, which has the property of absorbing solar energy with a wavelength of 300 nm to 3000 nm, and in particular, selectively absorbing infrared light with a wavelength of 900 nm to 2500 nm, converting it to heat, or re-radiating it.

[0225] On the other hand, particles of far-infrared emitting material have the ability to receive the energy absorbed by cesium tungsten oxide, which is an infrared absorbing material, convert the energy into thermal energy of mid- to far-infrared wavelengths, and radiate it. ２ The particles convert this energy into thermal energy with a wavelength of 2,000 nm or more and 20,000 nm or less and radiate it. Therefore, by having the far-infrared emitting material capable of emitting far-infrared rays and the composite tungsten oxide particles coexist inside or on the surface of the fiber, the solar energy absorbed by the composite tungsten oxide particles is efficiently consumed inside and on the surface of the fiber, resulting in more effective heat retention.

[0226] The content of the far-infrared emitting substance in the infrared absorbing fiber is not particularly limited, and can be selected depending on the performance required of the infrared absorbing fiber.

[0227] The infrared absorbing fiber of this embodiment preferably contains the far-infrared emitting substance in a proportion of, for example, 0.001% by mass or more and 80% by mass or less relative to the solid content of the fiber.

[0228] This is because, by setting the content of the far-infrared emitting substance to 0.001% by mass or more, a sufficient thermal energy radiation effect can be obtained even if the fabric containing the infrared-absorbing fiber is thin. Also, by setting the content of the far-infrared emitting substance to 80% by mass or less, it is possible to more reliably avoid a decrease in spinnability of the infrared-absorbing fiber due to clogging of the filter, yarn breakage, etc. during spinning. (2) Method for producing infrared-absorbing fiber A method for producing the infrared-absorbing fiber of this embodiment will be described. The method for producing the infrared-absorbing fiber of this embodiment can produce the infrared-absorbing fiber already described, so a description of the matters already described will be omitted.

[0229] The method for producing an infrared absorbing fiber of this embodiment may include an infrared absorbing fiber production step of preparing an infrared absorbing fiber containing a fiber and composite tungsten oxide particles.

[0230] The composite tungsten oxide particles and fibers have already been explained, so a detailed explanation will be omitted here.

[0231] In the infrared absorbing fiber manufacturing process, specifically, for example, composite tungsten oxide particles can be disposed in one or more locations selected from the surface and the interior of the fiber.

[0232] The method for disposing composite tungsten oxide particles in one or more locations selected from the surface and interior of a fiber is not particularly limited. For example, any of the following methods (a) to (d) can be used: (a) A method in which composite tungsten oxide particles are directly mixed into the raw polymer of a synthetic fiber and then spun. (b) A method in which a masterbatch is prepared in advance by incorporating a high concentration of composite tungsten oxide particles into a portion of the raw polymer, and the masterbatch is diluted to a predetermined concentration before spinning. (c) A dispersion solution is prepared in advance by dispersing composite tungsten oxide particles in a raw monomer or oligomer solution. The desired raw polymer is then synthesized using this dispersion solution, and the composite tungsten oxide particles are simultaneously dispersed in the raw polymer and spun. (d) A method in which composite tungsten oxide particles are attached to the surface of fibers obtained by previous spinning using a binder or the like.

[0233] Here, the above methods (a) to (d) will be further explained with specific examples. Method (a): This will be explained using an example in which polyester fibers are used as the fibers.

[0234] First, a composite tungsten oxide particle dispersion is added to polyethylene terephthalate resin pellets, which are a thermoplastic resin, and the mixture is mixed uniformly in a blender. The solvent is then removed. The mixture from which the solvent has been removed is melt-kneaded in a twin-screw extruder to obtain a masterbatch containing the composite tungsten oxide particles. The resulting masterbatch is melt-mixed near the melting temperature of the resin and spun by, for example, various known methods to produce infrared-absorbing fibers.

[0235] The method for producing the masterbatch is not particularly limited. For example, a masterbatch in which the composite tungsten oxide particles are dispersed in a thermoplastic resin can be prepared by first melt-mixing a composite tungsten oxide particle dispersion, powder or pellets of a thermoplastic resin, and, if necessary, other additives, using a kneader while removing the solvent.

[0236] The kneading machine is not particularly limited, and for example, one or more types selected from mixers such as a Riboblender, a tumbler, a Nauta mixer, a Henschel mixer, a super mixer, and a planetary mixer, as well as a Banbury mixer, a kneader, a roll, a kneader-ruder, a single-screw extruder, and a twin-screw extruder can be used.

[0237] The method for preparing the mixture in which the composite tungsten oxide particles are dispersed in the resin is not limited to the above-mentioned form.

[0238] For example, after preparing a composite tungsten oxide particle dispersion, first remove the dispersion medium from the dispersion by a known method.Then, the powder obtained by removing the dispersion medium, thermoplastic resin powder particles or pellets, and other additives as necessary are uniformly melt-mixed to produce a mixture in which composite tungsten oxide particles are dispersed in a thermoplastic resin.In addition, to produce a mixture in which composite tungsten oxide particles are dispersed in a thermoplastic resin, a method can also be used in which composite tungsten oxide particles are directly added to a thermoplastic resin and melt-mixed.

[0239] A mixture of the composite tungsten oxide particles obtained by the above-described method and a thermoplastic resin is kneaded in a vented single-screw or twin-screw extruder and processed into pellets, thereby obtaining a masterbatch containing infrared-absorbing particles.

[0240] This masterbatch and a target amount of a masterbatch made of polyethylene terephthalate without the addition of composite tungsten oxide particles are melt-mixed near the melting temperature of the resin and spun according to a known method. Method (b): A masterbatch containing composite tungsten oxide particles is prepared using a method similar to (a). Then, this masterbatch and a masterbatch made of polyethylene terephthalate without the addition of composite tungsten oxide particles are melt-mixed near the melting temperature of the resin to achieve a desired mixing ratio and spun according to a known method, thereby producing infrared-absorbing fibers. Method (c): For example, a case where urethane fibers are used as the fibers will be described.

[0241] A polymeric diol containing composite tungsten oxide particles is reacted with an organic diisocyanate in a twin-screw extruder to synthesize an isocyanate-terminated prepolymer, which is then reacted with a chain extender to produce a polyurethane solution (raw polymer). The polyurethane solution can be spun according to various known methods to produce infrared-absorbing particles. Method (d): This method will be described using an example in which composite tungsten oxide particles are attached to the surface of natural fibers.

[0242] First, a treatment liquid is prepared by mixing composite tungsten oxide particles, one or more binder resins selected from acrylic, epoxy, urethane, and polyester, and a solvent such as water.

[0243] Next, natural fibers are immersed in the prepared treatment solution, or the natural fibers are impregnated with the prepared treatment solution by padding, printing, spraying, or the like, and then dried. This allows the composite tungsten oxide particles to adhere to the natural fibers. Method (d) can also be applied to synthetic fibers, semi-synthetic fibers, regenerated fibers, inorganic fibers, or blends, doubling, or mixed fibers thereof, in addition to the natural fibers described above.

[0244] The method for preparing the composite tungsten oxide particle dispersion liquid that can be used when carrying out the above-mentioned methods (a) to (d) is not particularly limited, and for example, the dispersion liquid can be prepared by the method already described for the infrared absorbing particle dispersion liquid.

[0245] The dispersion medium for the composite tungsten oxide particle dispersion is not particularly limited and can be selected according to the fibers to be mixed. For example, various common organic solvents such as alcohols, ethers, esters, ketones, and aromatic compounds, as well as water, can be suitably used.

[0246] When the composite tungsten oxide particles are attached to or mixed with fibers or the polymers that are their raw materials, the dispersion of the composite tungsten oxide particles can be directly mixed with the fibers or the polymers that are their raw materials. If necessary, the pH can be adjusted by adding an acid or alkali to the dispersion of the composite tungsten oxide particles, and various surfactants, coupling agents, etc. can be added to further improve the dispersion stability of the composite tungsten oxide particles.

[0247] As described above, the infrared-absorbing fiber according to this embodiment contains composite tungsten oxide particles as an infrared-absorbing component. Even with a small content of composite tungsten oxide particles, the infrared-absorbing fiber according to this embodiment efficiently absorbs near-infrared rays from sunlight and converts them into heat, making it possible to provide a fiber with excellent heat retention even with a small content of composite tungsten oxide particles. Furthermore, because the infrared-absorbing fiber according to this embodiment can have a low content of composite tungsten oxide particles, it does not impair the design of the textile product and avoids impairing basic fiber properties such as strength and elongation. As a result, the fiber according to this embodiment can be used in a variety of applications, such as textile products requiring heat retention, such as cold weather clothing, sportswear, stockings, curtains, and other industrial textile products. Furthermore, when the infrared-shielding textile structure according to this embodiment is used in clothing, the amount of infrared rays contained in natural light that reach the human skin can be reduced, thereby reducing damage to the skin. When the textile product of this embodiment is used as a curtain and placed on a window of a building, the curtain absorbs infrared rays contained in sunlight and has an infrared-blocking function. This blocks infrared rays from sunlight entering the window, thereby suppressing an increase in room temperature in the summer. Furthermore, the infrared-absorbing fiber of this embodiment has excellent infrared absorption performance even with a small content of composite tungsten oxide particles, which are infrared-absorbing particles. This prevents transmission and reflection of infrared light, preventing so-called voyeurism while preventing damage to the texture of the fiber. Therefore, it can be used for various purposes as an infrared-absorbing fiber for preventing so-called voyeurism. [Textile Products] The textile product of this embodiment is obtained by processing the infrared-absorbing fiber described above and can contain the infrared-absorbing fiber described above. The textile product of this embodiment can also be composed of the infrared-absorbing fiber described above. (1) The voyeurism prevention function of the textile product of this embodiment against CCD cameras. Fabrics using the infrared-absorbing fiber of this embodiment and textile products such as clothing using this fabric have a content of composite tungsten oxide particles, for example, cesium-tungsten composite oxide, per unit area of ​​0.08 g / m. ２If the above is the case, it is possible to prevent infrared surreptitious photography (viewing with a CCD camera) in accordance with the Japan Spinners' Association test (Voken standard "BQE A 033").

[0248] In the textile product (infrared shielding textile structure) using the infrared absorbing fiber of this embodiment, the content of the composite tungsten oxide particles per unit area is 0.08 g / m as described above, from the viewpoint of providing a function to prevent surreptitious photography by a CCD camera. 2 More preferably, it can be 0.15 g / m or more. 2 More preferably, it is 0.20 g / m or more. 2 The upper limit of the content per unit area of ​​the composite tungsten oxide particles in the textile product of this embodiment is not particularly limited, but is, for example, 4.5 g / m 2 You can do the following:

[0249] Therefore, the content per unit area of ​​the composite tungsten oxide particles in the textile product of this embodiment is 0.08 g / m 2 4.5g / m or more 2 The thickness can be less than 0.15 g / m 2 4.5g / m or more 2 More preferably, it is 0.20 g / m or less. 2 4.5g / m or more 2 The following is the result.

[0250] The content of composite tungsten oxide particles per unit area of ​​the textile product of this embodiment is 0.08 g / m 2 If this is the case, the average reflectance of the textile product in the infrared region (wavelengths of 800 nm to 1300 nm) can be 65% or less. If the average reflectance of the textile product of this embodiment is 65% or less, it is possible to prevent surreptitious infrared photography (viewing with a CCD camera) in clothing that uses the textile product of this embodiment as a woven or knitted fabric. The average reflectance of the textile product of this embodiment is more preferably 60% or less, and even more preferably 55% or less.

[0251] The average reflectance of the textile product of this embodiment can be selected by the content per unit area of ​​the composite tungsten oxide particles. For example, the content per unit area of ​​the composite tungsten oxide particles of the textile product of this embodiment can be selected to be 0.15 g / m 2By setting the content of the composite tungsten oxide particles per unit area of ​​the textile product to 0.20 g / m or more, the average reflectance of the textile product can be set to 60% or less. 2 By setting the reflectance at or above this level, the average reflectance of the textile product can be set to 55% or less.

[0252] The content of composite tungsten oxide particles per unit area of ​​the textile product of this embodiment is 4.5 g / m 2 If the average reflectance exceeds 4.5 g / m, the average reflectance will be lower than 0.07%, but even if the average reflectance is lowered, the effect of preventing surreptitious photography by infrared rays will not be further improved. Therefore, the content of the composite tungsten oxide particles per unit area of ​​the textile product of this embodiment is set to 4.5 g / m as described above. 2 It can be less than 3.5 g / m 2 The content of the composite tungsten oxide particles per unit area may be 3.5 g / m or less. 2 However, if the composite tungsten oxide particles are contained in an excessive amount per unit area of ​​the textile product, it may be difficult to develop certain colors when dyeing the textile product.

[0253] In addition, the average reflectance of textile products that do not contain composite tungsten oxide particles in the infrared region (wavelengths of 800 nm to 1300 nm) is 77%, as confirmed in the Reference Example below, and this average reflectance makes it possible to take surreptitious photographs using infrared light (viewing with a CCD camera).

[0254] The average reflectance is the average value of the reflectance of a textile product measured with a spectrophotometer at 5 nm intervals in the wavelength range of 800 nm or more and 1300 nm or less.

[0255] Regarding solutions to prevent infrared surreptitious photography (viewing with a CCD camera), we will explain how we focus on the reflectivity of textile products.

[0256] When we look at an object with our eyes, we can recognize it because the light that hits the object is reflected and our eyes form an image of the object, and the same is true for images captured by a camera.

[0257] In addition, the textile product contains infrared-absorbing composite tungsten oxide particles at one or more locations selected from the surface and interior of the fiber, and when the textile product is irradiated with light, the composite tungsten oxide particles absorb the infrared light, thereby reducing the reflectance in the infrared wavelength range exceeding 780 nm. That is, the reflectance of infrared light among the light components irradiated onto the textile product of this embodiment is reduced. As a result, even if the textile product of this embodiment is photographed with a CCD camera, the image will be unclear due to the reduced reflectance in the wavelength range exceeding 780 nm.

[0258] It is known that the wavelength range of widely used CCD cameras is 400 nm to 1200 nm. The textile product of this embodiment reduces the reflectance of the irradiated light components in the infrared wavelength range exceeding 780 nm, making it possible to prevent surreptitious photography using infrared rays (viewing with a CCD camera). Up to this point, we have explained the use of a CCD camera as an example of an imaging device used for surreptitious photography using infrared rays, but the textile product of this embodiment can prevent surreptitious photography using imaging devices capable of capturing infrared rays, regardless of the type of camera.

[0259] On the other hand, the light absorption in the visible light region of the composite tungsten oxide particles contained in the textile product of this embodiment is small compared to the light absorption in the infrared region of wavelengths exceeding 780 nm. In other words, since the light absorption in the visible light region of the composite tungsten oxide particles contained in the textile product of this embodiment is small, it is possible to freely impart colors to the textile product by dyeing or the like.

[0260] Specific examples will be described below, but the present invention is not limited to these examples. (1) Evaluation Method (1-1) Powder X-ray Diffraction Pattern The powder X-ray diffraction pattern (XRD pattern) of the composite tungsten oxide particles was measured using a powder X-ray diffractometer (BRUKER D2 PHASER). The powder X-ray diffraction pattern was measured using CuKα radiation as the radiation source, with a tube voltage of 45 kV and a tube current of 40 mA. (1-2) STEM Image and HAADF Image Observation The obtained composite tungsten oxide particles were observed using a transmission electron microscope. High-angle angular dark-field images (HAADF) were also observed using a JEOL STEM (model: JEM-ARM200F). The atomic number (Z) contrast in an HAADF image is proportional to the square of the atomic number of the atoms in the particle and the number of atoms. The more heavier atoms there are, the brighter the contrast. Therefore, the brightest and second brightest contrasts are W, and the third brightest contrast is Cs, and it is thought that O cannot be identified.

[0261] The sample was placed on a Cu mesh with a support film by the dispersion method and observed.

[0262] During the observation, a high-angle scattering dark-field image (STEM-HAADF) was acquired at an accelerating voltage of 200 kV. This observation image was obtained by detecting only the transmitted electrons with large scattering angles among the electrons that had passed through the sample, and as described above, contrast due to differences in composition can be obtained. Note that since the magnitude of the scattering angle is proportional to the square of the atomic number (Z), the higher the atomic number of the element, the brighter the contrast. In the case of the composite tungsten oxide particles prepared in the examples and comparative examples, it is possible to distinguish Cs and W based on the difference in contrast.

[0263] In the evaluation, we used the difference in contrast intensity at tungsten columns (W columns), which are spots (points) where tungsten is located, in the STEM-HAADF image to distinguish between areas with and without W defects. If W is missing, the maximum value of Z contrast at that spot decreases.

[0264] The contrast of the observed STEM-HAADF images was evaluated and observed using Digital Micrograph (Version 3.43.3213.0) manufactured by Gatan Corp. The observed data was read into this software, and the contrast of the relevant area was extracted using the line profile function.

[0265] For the STEM-HAADF image, particles with a size of 50 nm or more were selected from the dispersed composite tungsten oxide particles to suppress deterioration due to the electron beam. The particle size used to select particles for observation was the diameter of the smallest encompassing circle that contained the particle. Furthermore, in order to clearly distinguish the Z contrast of W atoms, the observation field size was set to 20 nm square or more and 50 nm square or less.

[0266] Figure 5 shows the hexagonal Cs, a Cs-W-O compound with a hexagonal crystal structure. ０．３３ WO ３ 5 shows the crystal structure in the

[001] incident direction, i.e., on the (001) plane. W / W columns 501, in which only W atoms 51 are arranged, and W / Cs columns 502, in which W atoms 51 and Cs atoms, the M element 53, are alternately arranged, are arranged. The region S between the double arrows indicating the a-axis length and the b-axis length in the figure forms a unit cell. W columns and Cs columns exist in the c-axis direction, which is perpendicular to the paper surface, and there are three W columns and one Cs column per region S. To calculate the percentage of dark areas in the Z contrast of tungsten atoms in the STEM-HAADF image, the number of W columns within the observation field was first counted with reference to the crystal structure shown in FIG. 5 .

[0267] Next, the maximum Z contrast value of the spots in each W column within the observation field was calculated using the software, and the average value was calculated. In addition, the number of dark areas, which are spots where the maximum contrast value of the spots in each W column within the observation field is 95% or less of the average value, was counted.

[0268] The ratio of the number of dark areas in the observation field to the number of W columns in the observation field was then determined. (1-3) Transmitted Light Profile The optical properties of the infrared absorbing particle dispersion were measured using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.) to measure the transmitted light profile at 5 nm intervals in the wavelength range of 200 nm to 2600 nm. (1-4) Composition Analysis The ratio of each component contained in the composite tungsten oxide particles was evaluated by the following method.

[0269] The mass proportion of Cs was determined as an average value of three measurements for each sample using a polarized Zeeman atomic absorption spectroscopy (AAS, model: ZA3300, manufactured by Hitachi High-Tech Corporation).

[0270] The mass ratio of W was determined as the average value of three analyses of each sample performed using inductively-coupled plasma optical emission spectroscopy (ICP-OES, model: ICPE-9800, manufactured by Shimadzu Corporation).

[0271] The mass proportion of O was determined as the average value of three analyses per sample performed using an infrared detector for oxygen detection (infrared absorption spectroscopy (IRS)) with an oxygen / nitrogen / hydrogen analyzer (ON-836, LECO Japan Corp.). [Example 1] (1) Production of composite tungsten oxide particles Composite tungsten oxide particles were produced and evaluated using the composite material production apparatus 10 shown in FIG. 1 and the reduction treatment apparatus shown in FIG. 2. Specific conditions are described below.

[0272] The composite material manufacturing apparatus 10 has a storage section 11 containing a solution containing a W element source and an M element source, which are raw material solutions; a two-fluid nozzle 12 that forms droplets of the raw materials and also forms a flame; and a reaction tube 13 connected to a filter 14 that collects the formed composite tungsten oxide particles.

[0273] The supply rate of the raw material solution to the two-fluid nozzle 12 was set to 3 g / min. The flow rate of oxygen, which was a carrier gas, was set to 15 L / min, controlled by the ejector 15. The air flow rate in the ejector 15 was controlled to be within the range of 160 L / min to 180 L / min.

[0274] Propane gas and oxygen gas were used to form the flame by the two-fluid nozzle 12, with the flow rate of the propane gas being 1.2 L / min and the flow rate of the oxygen gas being 6.0 L / min.

[0275] The raw material is W(CO) ６ in tetrahydrofuran (THF) (a solution containing a W element source) and a solution in which cesium acetate, an M element source, is dissolved in ethanol (a solution containing an M element source) were used and stored in the storage unit 11. The mixed solution, which was the raw material, was prepared so that the ratio of the amount of substance of Cs (Cs) as the M element contained therein to the amount of substance of tungsten (W), Cs / W, was 0.37.

[0276] The raw material solution and oxygen as a carrier gas were supplied from the storage section 11 to the two-fluid nozzle 12 to form an aerosol (aerosol forming step).

[0277] As described above, propane gas and oxygen gas were supplied to the two-fluid nozzle 12 to form a flame reaction field, and the formed aerosol was supplied into the flame and subjected to heat treatment (heat treatment process).

[0278] In the heat treatment step, the heat treatment conditions were selected so that the composite tungsten oxide particles obtained after the heat treatment step would have appropriate W atom deficiencies and heterogeneous phases, and so that the composite tungsten oxide particles would have spots with reduced Z contrast of W atoms after the reduction treatment step. Specifically, the heat treatment conditions were selected based on the results of tests conducted in advance. Note that in the heat treatment step, the raw material was heat treated at a temperature of 550°C or higher.

[0279] The composite tungsten oxide particles obtained in the heat treatment step were introduced into reaction tube 13. Cooling water piping 131 was arranged around reaction tube 13, and cooling water was circulated through it. The composite tungsten oxide particles introduced into reaction tube 13 were collected by filter 14, which was a bag filter.

[0280] The composite tungsten oxide particles obtained after the heat treatment step were evaluated for their XRD patterns.

[0281] Figure 6 shows the XRD pattern of the obtained composite tungsten oxide particles. In Figure 6, the XRD pattern (A) shown as "As produced" is the XRD pattern of the composite tungsten oxide particles after the heat treatment step. Hexagonal Cs ０．３３ WO ３ (ICDD: 81-1245) or orthorhombic Cs ４ W １１ O ３５ (ICDD:51-1891) and a small amount of cubic pyrochlore (Cs ２ O) ０．４４ W ２ O ６ (ICDD: 47-0566) phase. The minor crystalline phase was identified using Rietveld analysis.

[0282] Further, reduction treatment was carried out using the reduction treatment device 20 shown in FIG.

[0283] As shown in FIG. ２ In a gas flow of 97% by volume of Ar, a heater 22 was provided around the reaction tube 21, and the temperature was raised from room temperature to 500°C. After the part where the container 23 was placed reached the reduction treatment temperature, the part was maintained at that temperature for 2 hours, and then cooled to room temperature to perform reduction treatment (reduction treatment step). In this way, reduced particles, which are composite tungsten oxide particles according to Example 1, were obtained.

[0284] Figure 6 shows the XRD pattern of the obtained composite tungsten oxide particles. In Figure 6, the XRD pattern (B) shown as "Heat treated" is the XRD pattern of the composite tungsten oxide particles after the reduction treatment step. The obtained XRD pattern shows that Cs ０．３３ WO ３The diffraction peaks included only the peaks of , , and it was confirmed that the crystal system was hexagonal.

[0285] The composite tungsten oxide particles after the reduction treatment step according to Example 1 were subjected to the composition analysis described above, and the Cs / W ratio, which is the ratio of the amounts of cesium and tungsten, was determined. As a result, it was confirmed that the Cs / W ratio decreased from 0.37 in the starting composition to 0.34. However, the value of 0.34 is 0.01 higher than the theoretical composition ratio of 0.33, and since the XRD pattern shows a single phase, it is believed that there is almost no Cs deficiency.

[0286] Furthermore, when the composition of the composite tungsten oxide particles was analyzed, it was confirmed that the O / W ratio, which is the ratio of the amounts of oxygen and tungsten, was 2.841. In the following description, the composite tungsten oxide particles were evaluated using XRD patterns and Cs ０．３３ WO ３ (2) Production of infrared absorbing particle dispersion liquid 10 mass% of the composite tungsten oxide particles after the reduction treatment step according to Example 1, 10 mass% of an acrylic polymer dispersant (an acrylic dispersant with an amine value of 48 mg KOH / g and a decomposition temperature of 250°C), and 80 mass% of toluene were weighed out. The weighed materials were placed in a paint shaker together with zirconia beads having a diameter of 0.05 mm, and a dispersion treatment was carried out for 100 minutes using the paint shaker to obtain the infrared absorbing particle dispersion liquid according to Example 1, Cs ０．３３ WO ３ A particle dispersion was obtained.

[0287] The average particle size of the composite tungsten oxide particles in the dispersion liquid of Example 1 obtained was measured (measured by a transmission electron microscope) and was found to be 27.2 nm.

[0288] The average particle size of the composite tungsten oxide particles was calculated by observing them in three fields of view using a transmission electron microscope.Specifically, the images of a total of 600 to 700 composite tungsten oxide particles were observed in three fields of view, and the area of ​​each particle was calculated from the binarized data, and the equivalent circle diameter of each particle was calculated.Then, the particle sizes of all the composite tungsten oxide particles evaluated, that is, the arithmetic mean value of the equivalent circle diameters, was taken as the average particle size.

[0289] Cs according to Example 1 ０．３３ WO ３ The particle dispersion liquid was separated, and the solvent was removed to obtain Cs ０．３３ WO ３ particles were obtained.

[0290] Cs, which is the composite tungsten oxide particle according to Example 1 ０．３３ WO ３ STEM-HAADF images of the particle are shown in Figures 7A and 7B. Figure 7A shows a STEM-HAADF image of the entire particle. Figure 7B shows an enlarged image of a square region 71 in the particle shown in Figure 7A. As shown in Figure 7B, the size of the observation field was adjusted to approximately 20 nm square. Approximately 15 dark areas, which are regions with low Z contrast of W atoms, were observed within this particle. The number of tungsten columns in this field of view was calculated to be 2,249 columns, based on the size of the unit cell and the size of the field of view, since there were three tungsten columns in the unit lattice. In other words, W vacancies exist in 0.67% of the columns.

[0291] The dark areas, which are areas with low contrast, were defined as spots where the maximum value of the Z contrast of the tungsten column spots was 95% or less of the average value.

[0292] 8A to 8F show line profiles including W defects in STEM-HAADF images of the composite tungsten oxide particles in Example 1. 8A to 8F correspond to the line profiles of lines L1 to L6 in FIG. 7B, respectively.

[0293] Although the Z contrast may vary even within the same line due to factors such as particle thickness and inclination relative to the electron beam, the maximum Z contrast values ​​of the spots of each tungsten column within the field of view were averaged to determine the Z contrast intensity of W atoms in a bulk region without W defects. Using the average value of the maximum Z contrast values ​​of the spots of each tungsten column within the field of view as the standard, the locations where the maximum contrast value of the tungsten column spots was 95% or less of the average value were determined to be W defects.

[0294] On the line L1 shown in FIG. 8A, the maximum value of the Z contrast at point P1 is 89.1% of the average value, and at point P2 it drops to 88.4%, and these points are W-deficient portions.

[0295] On line L2 shown in FIG. 8B, the maximum value of Z contrast decreased to 89.3%, 92.8%, 93.2%, and 91.35% of the average value at points P3 to P6, respectively.

[0296] On the line L3 shown in FIG. 8C, at points P7 and P8, the maximum values ​​of the Z contrast decreased to 86.95% and 85.6%, respectively, relative to the average value.

[0297] On line L4 shown in FIG. 8D, at points P9 and P10, the maximum Z contrast decreased to 89.2% and 89.4%, respectively, relative to the average value.

[0298] On the line L5 shown in FIG. 8E, at point P11, the maximum value of the Z contrast decreased to 88.6% of the average value.

[0299] On line L6 shown in FIG. 8F, at points P12 to P15, the maximum value of Z contrast decreased to 94.0%, 93.2%, 93.4%, and 90.6% of the average value, respectively.

[0300] FIG. 12A is a STEM-HAADF image of the composite tungsten oxide particle according to Example 1, taken from the

[110] incident angle, i.e., an image of the prism surface. In FIG. 12A, a defect plane 121 due to a defect of W atoms is formed in a direction perpendicular to the c-axis. The defect is a defect in the basal plane (001) plane. FIG. 12B is an enlarged view of the defect plane in FIG. 12A. It was confirmed that adjacent to the defect, there is a space 122 approximately 3 nm long in the c-axis direction where no Cs or W atoms are present. These defect planes 121, which are defects in the basal plane, and the space 122 along the c-axis direction where no Cs or W atoms are present are thought to be due to the fact that they remained as the interface of the crystallized region when the Cs and W atoms rearranged within the crystal during the heat treatment process.

[0301] Furthermore, it was confirmed that there was a distorted structure in which the crystal structure was shifted by a quarter period across a defect plane 121 caused by a defect of W atoms about 30 nm in length in the direction perpendicular to the c-axis. Figure 13 is a diagram showing a schematic diagram of the arrangement of W atoms and Cs atoms in Figures 12A and 12B.

[0302] The transmitted light profile was measured under the above-mentioned conditions as the optical properties of the infrared absorbing particle dispersion liquid according to Example 1. The results of the transmitted light profile are shown in FIG.

[0303] When measuring the optical properties, the infrared absorbing particle dispersion was adjusted so that the visible light transmittance was 80%.

[0304] A molar absorption coefficient curve was obtained from the absorption curve obtained when measuring the transmitted light profile of the infrared absorbing particle dispersion liquid according to Example 1. The molar absorption coefficient curve was then separated into absorption curves of three absorption components: an absorption curve of localized surface plasmon resonance (LSPR⊥) in a direction perpendicular to the c-axis, an absorption curve of localized surface plasmon resonance (LSPR / / ) in a direction parallel to the c-axis, and an absorption curve of polaron absorption. The results are shown in FIG. 15A. In FIG. 15A, "exp." is the actual measured value, and "calc" is the sum of the absorption curves of the three absorption components.

[0305] The peak positions, peak intensities, and integrated intensities of the absorption curves of the three absorption elements are shown in Table 2. Furthermore, Table 3 shows the ratios of the integrated intensities of the absorption curves of the three absorption elements to the integrated intensity of the molar extinction coefficient curve.

[0306] Furthermore, the chromaticity L ＊ , a ＊ , b ＊ The color system values ​​were calculated. The results are shown in Table 4. (3) Production of infrared absorbing fiber The toluene was removed from the infrared absorbing particle dispersion liquid of Example 1 using a spray dryer. ０.３３ WO ３ A dispersed powder (Powder A) was obtained.

[0307] The obtained dispersed powder (powder A) was added to polyethylene terephthalate resin pellets, which is a thermoplastic resin, and mixed uniformly in a blender. After that, the mixture was melt-kneaded and extruded in a twin-screw extruder, and the extruded strands were cut into pellets. By the above operations, the heat ray absorbing component Cs ０.３３ WO ３ A masterbatch (masterbatch a1) containing 40% by mass of particles was obtained.

[0308] The masterbatch a1 was melt-spun and then drawn to produce a polyester multifilament yarn a1. The resulting polyester multifilament yarn a1 was cut to produce polyester staple a1.

[0309] Also, Cs ０．３３ WO ３ A particle-free masterbatch was melt-spun and then drawn to produce polyester multifilament yarn a2. The obtained polyester multifilament yarn a2 was cut to produce polyester staple a2. Spun yarn a1 was produced from polyester staple a1, and spun yarn a2 was produced from polyester staple a2. (4) Production of a warm knit as a textile product Knit product a1, which is the textile product according to Example 1 having near-infrared absorbing properties, was obtained using spun yarn a1 and spun yarn a2. Knit product a1 was produced by adjusting the blending ratio of spun yarn a1 and spun yarn a2 so that the solar reflectance was 8%. (Evaluation of temperature-raising effect) Next, the temperature-raising effect on the back surface of the fabric of the produced knit product a1 was measured as follows.

[0310] In an environment of 20°C and 60% RH, a lamp with a spectrum approximating sunlight (solar simulator XL-03E50 modified by Seric Co., Ltd.) was irradiated from a distance of 30 cm from the fabric of the knit product, and the temperature of the backside of the fabric was measured at regular intervals (0 seconds, 30 seconds, 60 seconds, 180 seconds, 360 seconds, and 600 seconds) using a radiation thermometer (HT-11 by Minolta Co., Ltd.).

[0311] The evaluation results are shown in Table 5. (Evaluation of voyeurism prevention) Using spun yarn a1 and spun yarn a2, precursor knit fabrics according to Example 1 were produced so that the amount of composite tungsten oxide particles used per unit area was the value shown in Table 6. In Example 1, six types of precursor knit fabrics were produced, with the content of composite tungsten oxide particles per unit area varying from concentration B to concentration G, as shown in Table 6.

[0312] The precursor knit fabric was then dyed brown with a cationic dye to produce the knit fabric for evaluating the anti-secret photography method according to Example 1. The reason for dyeing the knit fabric for evaluating the anti-secret photography method according to Example 1 was to avoid the situation where undyed white knit products would be see-through even with visible light.

[0313] Additionally, as a reference example, a knitted fabric for evaluation of voyeurism prevention according to the reference example was produced using only spun yarn a2, which did not contain composite tungsten oxide particles, in the same manner as the knitted fabric for evaluation of voyeurism prevention according to this example. (Average Reflectance of Knitted Product According to Example 1) Then, using a spectrophotometer manufactured by Hitachi, Ltd., the reflectance of the knitted fabric according to Example 1 was measured at 5-nm intervals in the wavelength range of 800 nm to 1300 nm, and the average reflectance was calculated. The reflectance measurement results in the wavelength range of 300 nm to 2500 nm are shown in Figure 16A, and the evaluation results of the average reflectance of the fabric are shown in Table 6. (Evaluation of Knitted Fabrics According to Example 1 and Reference Example) Next, the knitted fabrics according to Example 1 and Reference Example were evaluated for "infrared voyeurism prevention (viewing with a CCD camera)" using the following test method in accordance with the Japan Spinners Inspection Association's Boken standard "BQE A 033." "Test Method" (Step 1) A test piece of the knitted fabric was placed over a transmission test plate (eye chart) and placed on a test stand. (Second step) Using an infrared projector, approximately 7 mW / cm was applied to the surface of the test piece. 2(Step 3) The test piece is photographed normally with a digital camera. (Step 4) The test piece is photographed through transmission with an infrared camera. (Step 5) The photographed image is checked to determine whether or not infrared light is transmitted. "Determination results" The knit fabric according to Example 1 was not observed to transmit infrared light. In contrast, the knit fabric according to the Reference Example was observed to transmit infrared light. [Comparative Example 1] (1) Production of composite tungsten oxide particles Cs was added to 0.330 kg of water. ２ CO ３ 0.216 kg was dissolved in H ２ WO ４ After adding the mixture to 1.000 kg of the mixture and thoroughly stirring, the mixture was dried to obtain a dried product. ２ 5% H by volume with gas as carrier ２ The dried product was placed in an electric furnace and heated while gas was being supplied, and calcined at a temperature of 800°C for 1 hour. After that, the supply gas was changed to N ２ The gas was switched to gas only, and the temperature was lowered to room temperature, obtaining a composite tungsten oxide coarse powder according to Comparative Example 1. (2) Production of Infrared-Absorbing Particle Dispersion 10% by mass of the obtained composite tungsten oxide coarse powder, 10% by mass of an acrylic polymer dispersant (an acrylic dispersant with an amine value of 48 mg KOH / g and a decomposition temperature of 250°C), and 80% by mass of toluene were weighed. The weighed materials were placed in a paint shaker together with zirconia beads with a diameter of 0.1 mm, and a dispersion treatment was carried out using the paint shaker for 2 hours to obtain an infrared-absorbing particle dispersion according to Comparative Example 1. The average particle size of the composite tungsten oxide particles in the obtained dispersion according to Comparative Example 1 (measured using a transmission electron microscope) was measured to be 25.1 nm. The average particle size was measured and calculated using the same procedures and conditions as in Example 1. The dispersion according to Comparative Example 1 was also sampled, and the solvent was removed to obtain the composite tungsten oxide particles according to Comparative Example 1, Cs ０．３３ WO ３ particles were obtained.

[0314] 9A and 9B show the composite tungsten oxide particles according to Comparative Example 1, Cs ０．３３ WO ３A STEM-HAADF image of a particle is shown. Figure 9A shows a STEM-HAADF image of the entire particle. Figure 9B shows an enlarged image of a square region 91 in the particle shown in Figure 9A. Powders synthesized via the solid-phase method have a fracture surface due to the long-term dispersion treatment. Since contrast is affected by the particle thickness, a region 91 in the center of the particle, where this effect is thought to be small, was enlarged and extracted.

[0315] In Figure 9B, low contrast regions of the Cs columns were confirmed at the locations indicated by arrows 92 and 93. The loss of these Cs columns is thought to be the result of Cs being desorbed during the long-term grinding process.

[0316] 10B to 10D show the results of extracting line profiles for lines L11 to L13, which are W / W columns, in the STEM-HAADF image shown in FIG. 10A. No points were found where the Z contrast of W atoms was 95% or less of the average contrast. In other words, it was confirmed that no W defects had occurred.

[0317] The transmitted light profile was measured under the above-mentioned conditions as the optical properties of the infrared absorbing particle dispersion liquid according to Comparative Example 1. The results of the transmitted light profile are shown in FIG.

[0318] Furthermore, a molar absorption coefficient curve was determined from the absorption curve obtained when measuring the transmitted light profile of the infrared absorbing particle dispersion liquid according to Comparative Example 1. The molar absorption coefficient curve was then separated into absorption curves of three absorption components: an absorption curve of localized surface plasmon resonance (LSPR⊥) in an orientation perpendicular to the c-axis, an absorption curve of localized surface plasmon resonance (LSPR / / ) in an orientation parallel to the c-axis, and an absorption curve of polaron absorption. The results are shown in FIG. 15B.

[0319] The peak positions, peak intensities, and integrated intensities of the absorption curves of the three absorption elements are shown in Table 2. Furthermore, Table 3 shows the ratios of the integrated intensities of the absorption curves of the three absorption elements to the integrated intensity of the molar extinction coefficient curve.

[0320] Furthermore, the infrared absorbing particle dispersion liquid according to Comparative Example 1 was diluted so that the visible light transmittance was 80%, and the chromaticity L ＊ , a ＊ , b ＊ The color system values ​​were calculated. The results are shown in Table 4. (3) Production of infrared absorbing fiber The toluene was removed from the infrared absorbing particle dispersion liquid of Comparative Example 1 using a spray dryer. ０.３３ WO ３ A dispersed powder (Powder B) was obtained.

[0321] The obtained dispersed powder (powder B) was added to polyethylene terephthalate resin pellets, which are thermoplastic resins, and after uniformly mixing in a blender, the mixture was melt-kneaded and extruded in a twin-screw extruder, and the extruded strands were cut into pellets. ０.３３ WO ３ A masterbatch containing 40% by mass of particles (masterbatch b1) was obtained.

[0322] Masterbatch b1 was melt-spun and then drawn to produce polyester multifilament yarn b1. The obtained polyester multifilament yarn b1 was cut to produce polyester staple b1. Spun yarn b1 was produced from polyester staple b1. (4) Production of a warm knit as a textile product Knit product b1, a textile product according to Comparative Example 1, was obtained using spun yarn b1 and spun yarn a2 produced in Example 1 that did not contain composite tungsten oxide particles. Knit product b1 was produced by adjusting the blending ratio of spun yarn b1 and spun yarn a2 so that the solar reflectance was 8%. (Evaluation of temperature-raising effect) Next, the temperature-raising effect on the back surface of the fabric of the produced knit product b1 was measured under the same conditions as in Example 1.

[0323] The evaluation results are shown in Table 5. Table 5 shows that there was no difference in the temperature rise on the back surface of the fabric of the knit products according to Example 1 and Comparative Example 1. [Evaluation of voyeurism prevention] (Evaluation of voyeurism prevention) A precursor knit fabric according to Comparative Example 1 was produced using spun yarn b1 and spun yarn a2 so that the amount of composite tungsten oxide particles used per unit area was the value shown in Table 6. In Comparative Example 1, six types of precursor knit fabrics were produced, with the content of composite tungsten oxide particles per unit area varying from concentration B to concentration G, as shown in Table 6.

[0324] Thereafter, the precursor knit fabric was dyed brown with a cationic dye to prepare a knit fabric for evaluation of voyeurism prevention according to Comparative Example 1.

[0325] The obtained knit fabric for evaluation of voyeurism prevention according to Comparative Example 1 was evaluated under the same conditions as in Example 1. The measurement results of reflectance are shown in Fig. 16B, and the evaluation results of the average reflectance of the fabric are shown in Table 6.

[0326]

[0327]

[0328]

[0329]

[0330]

[0331] It was confirmed that in the infrared absorbing particle dispersion liquid of Example 1 shown in FIG. 11A , even if the peak of the transmittance in the wavelength region of 500 nm to 600 nm was set to 75% or more, the bottom of the transmittance in the near-infrared region could be set to 5% or less.

[0332] In contrast to this, in the infrared absorbing particle dispersion liquid of Comparative Example 1 shown in FIG. 11B , when the peak of the transmittance in the wavelength region of 500 nm to 600 nm was set to 75% or more, the bottom of the transmittance in the near-infrared region could not be set to 5% or less, and it was confirmed that the near-infrared shielding effect was inferior.

[0333] Furthermore, Table 1 shows that the transmittance at a wavelength of 700 nm of the infrared absorbing particle dispersion of Example 1 is higher than that of the infrared absorbing particle dispersion composed of conventional composite tungsten oxide particles of Comparative Example 1, indicating that light on the long wavelength side of the visible light range (wavelengths of 380 nm or more and 780 nm or less) is also transmitted. This shows that the composite tungsten oxide particles of Example 1 are also capable of transmitting red light with a wavelength of around 800 nm, and therefore contribute to improving the color tone of conventional composite tungsten oxide particles.

[0334] From Table 4, the infrared absorbing particle dispersion liquid according to Example 1 has b ＊ is −0.61502, whereas the near infrared absorbing particle dispersion liquid according to Comparative Example 1 has b ＊ was -0.71411. ＊ The more negative the value, the more blue the dispersion is. Example 1 shows that the dispersion is less blue than the conventional composite tungsten oxide particles, which also contributes to improving color tone.

[0335] According to the results shown in Table 6, in the knit fabric for evaluation of voyeurism prevention according to Example 1, the content of composite tungsten oxide particles per unit area was 0.09 g / m ２ In contrast, in the knit fabric for evaluation of the voyeurism prevention method according to Comparative Example 1, the content of the composite tungsten oxide particles per unit area was 0.13 g / m. ２ It was confirmed that the effect of preventing transmission would not be realized unless the content of composite tungsten oxide particles per unit area was 0.09 g / m. Furthermore, the following points can be confirmed by comparing Figures 16A and 16B. In the reflectance curve of the knit fabric for evaluation of voyeurism prevention according to Example 1 shown in Figure 16A, the content of composite tungsten oxide particles per unit area was 0.09 g / m. ２ In contrast, the reflectance curve of the knit fabric for evaluation of voyeurism prevention according to Comparative Example 1 shown in FIG. 16B shows that the content per unit area of ​​the composite tungsten oxide particles is 0.09 g / m. 2At a concentration B of 0.05, the reflectance exceeds 65% at a wavelength of 1,050 nm. These results demonstrate that the composite tungsten oxide particles contained in the infrared-absorbing fiber of this embodiment have superior infrared absorption properties to conventionally known composite tungsten oxide particles. This application claims priority based on Japanese Patent Application No. 2023-170834, filed with the Japan Patent Office on September 29, 2023, the entire contents of which are incorporated herein by reference.

[0336] DESCRIPTION OF SYMBOLS 10 Composite material manufacturing apparatus 11 Storage section 12 Two-fluid nozzle 13 Reaction tube 131 Piping 14 Filter 15 Ejector 20 Reduction treatment device 21 Reaction tube 21A One port 21B Other port 22 Heater 23 Container 24 Composite tungsten oxide particle 30 Infrared absorbing particle dispersion 31 Infrared absorbing particle 32 Liquid medium 40 Infrared absorbing fiber 41 Fiber 42 Composite tungsten oxide particle 41A Surface 41B Interior CA Central axis 501 W / W row 502 W / Cs row 51 W atom 52 O atom 53 M element 54 Octahedron 55 Void 71 Regions L1 to L6 Lines P1 to P15 Points 91 Regions 92, 93 Arrows L11 to L13 Line 121 Missing surface 122 Space

Claims

1. A method for producing a composite tungsten oxide particle comprising: a fiber; and a composite tungsten oxide particle disposed at one or more locations selected from the interior and surface of the fiber, the composite tungsten oxide particle comprising a composite tungsten oxide, the composite tungsten oxide being represented by the general formula M ｘ W ｙ O ｚ (wherein M element is one or more elements selected from alkali metal elements, alkaline earth metal elements, 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; 0.20≦x / y≦0.37, 2.2≦z / y≦3.3), the crystal system is hexagonal, An infrared absorbing fiber, comprising 0.01% or more and 10% or less of spots in which the Z contrast of tungsten atoms has dropped to 95% or less of the average value in a STEM-HAADF image of the composite tungsten oxide particle from a [001] incidence angle.

2. The infrared absorbing fiber according to claim 1, wherein the M element of the composite tungsten oxide includes one or more elements selected from the group consisting of Rb and Cs.

3. The infrared absorbing fiber according to claim 1 or 2, wherein the average particle size of the composite tungsten oxide particles is 10 nm or more and 200 nm or less.

4. The infrared absorbing fiber according to claim 1 or 2, wherein the composite tungsten oxide particle has a defect plane in a direction perpendicular to the c-axis in a STEM-HAADF image from [110] incidence.

5. The infrared absorbing fiber according to claim 1 or 2, wherein the fiber is one or more types selected from a fiber group consisting of synthetic fibers, semi-synthetic fibers, natural fibers, regenerated fibers, and inorganic fibers, and a mixed yarn obtained by blending, doubling, or mixing two or more types of fibers selected from the fiber group.

6. The infrared absorbing fiber according to claim 5, wherein the synthetic fiber is one or more selected from the group consisting of polyurethane fibers, polyamide fibers, acrylic fibers, polyester fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, and polyether ester fibers.

7. The infrared absorbing fiber according to claim 5, wherein the semi-synthetic fiber is at least one type selected from the group consisting of cellulose-based fiber, protein-based fiber, chlorinated rubber, and hydrochloric rubber.

8. The infrared absorbing fiber according to claim 5, wherein the natural fibers are at least one type selected from the group consisting of vegetable fibers, animal fibers, and mineral fibers.

9. The infrared absorbing fiber according to claim 5, wherein the regenerated fiber is one or more selected from the group consisting of cellulose-based fiber, protein-based fiber, alginate fiber, rubber fiber, chitin fiber, and mannan fiber.

10. The infrared absorbing fiber according to claim 5, wherein the inorganic fiber is at least one type selected from the group consisting of metal fiber, carbon fiber, and silicate fiber.

11. A textile product containing the infrared absorbing fiber according to claim 1 or 2.

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