Infrared absorbing fiber and fiber product

Abstract

The present invention addresses the problem of providing an infrared-absorbing fiber containing composite tungsten oxide particles having excellent infrared-absorbing performance. An infrared absorbing fiber according to the present invention comprises a fiber and composite tungsten oxide particles provided at one or more positions selected from the inside and the surface of the fiber, the composite tungsten oxide particles comprising a composite tungsten oxide represented by the general formula MxWyOz (0.20 < = x / y < = 0.37, 2.2 < = z / y < = 3.3) and having a hexagonal crystal system, and the composite tungsten oxide particles have a particle diameter of 1-5 [mu] m and a particle diameter of 1-5 [mu] m. A STEM-HAADF image incident from [001] contains 0.01% to 10% of spots in which the Z contrast of tungsten atoms is reduced to 95% or less of the average value, in a number ratio.

Description

Technical Field

[0001] This invention relates to infrared absorbing fibers and fiber products. Background Technology

[0002] Functional cold-weather clothing with both heat-insulating and heat-generating functions has been proposed. Methods to improve cold-weather protection can be broadly categorized into three types.

[0003] The first method is to reduce the loss of heat generated by the body in order to maintain warmth.

[0004] As a specific means of the first method, the following methods can be cited, such as controlling the weaving structure of the cold-weather clothing, or making the fibers used hollow or porous, thereby physically increasing the air layer, thereby reducing the loss of heat generated by the human body to the outside and maintaining the insulation.

[0005] The second method utilizes the chemical and physical properties of the fibers contained in the cold-weather clothing to allow the fibers to retain heat.

[0006] The third method involves chemically and physically processing the fibers in the cold-weather clothing to radiate heat generated by the human body back to the body, or to convert some of the sunlight received by the cold-weather clothing into heat, thus using this active method to store heat.

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

[0008] As one of the third methods, it has been proposed to incorporate alumina-based, zirconium-based, and magnesium-based ceramic particles into the fiber itself, utilizing the far-infrared radiation effect or the light-to-heat conversion effect of these inorganic particles, as well as using dyes with high absorption rates in the near-infrared region. In other words, a method for actively absorbing external energy has been proposed.

[0009] For example, Patent Document 2 discloses a thermal radiation fiber, characterized by containing one or more inorganic microparticles with thermal radiation properties, wherein the inorganic microparticles have a thermal conductivity of 0.3 kcal / m 2 At least one of the metals and metal ions at temperatures above sec·℃.

[0010] Patent Document 3 discloses a near-infrared absorption processing method for cellulose-based fiber structures. By combining dyes with properties exhibiting greater absorption in the near-infrared region than black dyes with other dyes, the spectral reflectance of the fabric in the 750-1500 nm near-infrared absorption range is reduced to below 65%. Direct dyes, reactive dyes, naphthol dyes, and vat dyes are disclosed as dyes with greater absorption in the near-infrared region than black dyes.

[0011] In Patent Document 4, the applicant proposed a near-infrared absorbing fiber containing ultrafine particles with near-infrared absorption properties within the fiber, characterized in that... The ultrafine particles with near-infrared absorption properties are composite tungsten oxide ultrafine particles. The composite tungsten oxide ultrafine particles are those with an XRD peak intensity ratio of 0.13 or higher when the XRD peak intensity of the (220) plane of a silicon powder standard sample (NIST, 640c) is set to 1. The technology for fiber products using this fiber was also proposed.

[0012] Furthermore, when photographing the human body using a CCD camera or similar device with natural light as the light source, the infrared rays contained in the natural light can penetrate clothing and be seen on the body. In recent years, crimes 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 developed, and clothing made from these infrared shielding fibers (infrared shielding fiber structures) has been manufactured.

[0013] For example, Patent Document 5 discloses a knitted fabric made by attaching an infrared absorber selected from anthraquinone, indigo, benzoquinone, naphthoquinone or phthalocyanine to a core-sheath type synthetic fiber.

[0014] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-135605 Patent Document 2: Japanese Patent Application Publication No. 11-279830 Patent Document 3: Japanese Patent Application Publication No. 9-291463 Patent Document 4: International Publication No. 2018 / 235839 Patent Document 5: Japanese Patent Application Publication No. 2008-223171 Summary of the Invention The problem that the invention aims to solve Regarding infrared absorbing fibers, to prevent so-called "spy photography," it's necessary to prevent infrared light from passing through or reflecting while suppressing the content of infrared absorbing particles to avoid compromising the fiber's tactile feel. Therefore, an infrared absorbing fiber containing infrared absorbing particles with excellent infrared absorption properties is needed.

[0015] Therefore, one aspect of the present invention aims to provide an infrared absorbing fiber comprising composite tungsten oxide particles with excellent infrared absorption properties.

[0016] Methods for solving problems In one aspect of the present invention, an infrared absorbing fiber is provided, comprising fibers, and Composite tungsten oxide particles are disposed at more than one location selected from the interior and surface of the fiber. The composite tungsten oxide particles contain composite tungsten oxide. The composite tungsten oxide uses the general formula M x W y O z (Here, element M is one or more elements selected from alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I; W represents tungsten; O represents oxygen; 0.20 ≤ x / y ≤ 0.37; 2.2 ≤ z / y ≤ 3.3). The crystal system is hexagonal. Regarding the composite tungsten oxide particles, in the STEM-HAADF image incident from

[001] , there are spots containing 0.01% to 10% by number of tungsten atoms whose Z-contrast is reduced to less than 95% of the average value.

[0017] The effects of the invention According to one aspect of the present invention, an infrared absorbing fiber comprising composite tungsten oxide particles with excellent infrared absorption properties can be provided. Attached Figure Description

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[0049] The following describes specific examples of an infrared absorbing fiber and fiber article according to one embodiment of the present invention (hereinafter referred to as "this embodiment") with reference to the accompanying drawings. Furthermore, the present invention is not limited to these examples, but is intended to include all modifications within the meaning and scope equivalent to the claims, as shown in the claims.

[0050] Before describing the infrared absorbing fiber, let me first explain the composite tungsten oxide particles contained in the infrared absorbing fiber of this embodiment.

[0051] [Composite tungsten oxide particles] The composite tungsten oxide particles contain composite tungsten oxide. Furthermore, the composite tungsten oxide particles may be composed of composite tungsten oxide, but even in this case, the presence of unavoidable impurities cannot be ruled out.

[0052] The above-mentioned composite tungsten oxide is made of general formula M x W y O z express.

[0053] In the above general formula, element M can be selected from alkali metals, alkaline earth metals, rare earth elements, 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), Si (silicon), Ge (germanium), Sn (tin), Pb (lead), Sb (antimony), B (boron), F (fluorine), P (phosphorus), S (sulfur), Se (selenium), Br (bromine), Te (tellurium), Ti (titanium), Nb (niobium), V (vanadium), Mo (molybdenum), Ta (tantalum), Re (rhenium), Be (beryllium), Hf (hafnium), Os (osmium), Bi (bismuth), and I (iodine) as one or more elements. In addition, W represents tungsten, O represents oxygen, and x, y, and z preferably satisfy 0.20≤x / y≤0.37 and 2.2≤z / y≤3.3, respectively.

[0054] 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).

[0055] In addition, the crystal system of this composite tungsten oxide is hexagonal.

[0056] Furthermore, regarding composite tungsten oxide particles, in the STEM-HAADF image of composite tungsten oxide particles incident from

[001] , there are spots whose Z contrast decreases to less than 95% of the average value, containing tungsten atoms at a ratio of more than 0.01% to less than 10%.

[0057] (1) Regarding the composition The composite tungsten oxide contained in the composite tungsten oxide particles is as described above, derived from the general formula M. x W y O z The M, W, O, x, y, and z elements in the formula are as described above and will not be explained here.

[0058] The composite tungsten oxide can take the form of one or more tungsten bronze-type crystal structures, for example, selected from tetragonal, cubic, and hexagonal crystals. Furthermore, the composite tungsten oxide particles in this embodiment contain hexagonal composite tungsten oxide.

[0059] When the composite tungsten oxide has a hexagonal crystal structure, the transmittance of the particle in the visible light region is improved, and the light absorption in the near-infrared region is enhanced.

[0060] When composite tungsten oxide adopts a tetragonal or cubic tungsten bronze-type crystal structure, it also functions as an infrared shielding material. However, depending on the crystal structure adopted by the composite tungsten oxide, the light absorption position in the near-infrared region tends to change. Compared to cubic crystals, the light absorption position in the near-infrared region shifts towards longer wavelengths in tetragonal crystals, while in hexagonal crystals, it tends to shift even further towards longer wavelengths than in tetragonal crystals. Furthermore, along with this change in absorption position, the light absorption in the visible light region is lowest in hexagonal crystals, followed by tetragonal crystals, with cubic crystals exhibiting the highest visible light absorption. Therefore, in applications requiring the transmission of more visible light while blocking more infrared light, composite tungsten oxide with a hexagonal tungsten bronze-type crystal structure is preferred.

[0061] As described above, when the composite tungsten oxide has a hexagonal crystal structure, the light transmittance in the visible light region and the light absorption in the near-infrared region of the composite tungsten oxide particles are particularly improved. Therefore, the composite tungsten oxide particles preferably contain a hexagonal crystal structure. Furthermore, if one or more elements selected from Cs, Rb, K, Tl, Ba, and In are used in the M element, hexagonal crystals are easily formed. Therefore, the M element preferably contains one or more elements selected from Cs, Rb, K, Tl, Ba, and In, and more preferably contains one or more elements selected from Rb and Cs.

[0062] Here, we explain the configuration of the M element when the composite tungsten oxide has a hexagonal crystal structure.

[0063] An octahedron, consisting of W (tungsten) atoms and six O (oxygen) atoms as units—that is, an octahedron with O atoms at its vertices and W atoms at its center—is assembled with six of these octahedrons to form hexagonal gaps (tunnels) composed of O atoms. Then, an M element is placed in these gaps to form one unit, and these units are assembled in large quantities to form a hexagonal crystal structure.

[0064] When the composite tungsten oxide with a hexagonal crystal structure has a uniform crystal structure, the molar ratio of element M 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, it is assumed that by making the value of x / y 0.33, element M is disposed in all the hexagonal voids. Furthermore, the above x, y, and z mean the aforementioned general formula M x W y O z The x, y, and z values ​​are the same in the following cases.

[0065] Composite tungsten oxide has a composition in which tungsten trioxide (WO3) has added element M. Since tungsten trioxide lacks effective free electrons, it cannot achieve infrared absorption unless the oxygen-to-tungsten ratio is less than 3:1. However, in composite tungsten oxide, by adding element M to generate free electrons, infrared absorption can be achieved. Therefore, the oxygen-to-tungsten ratio can be 3:1 or less. Alternatively, the oxygen-to-tungsten ratio can also exceed 3:1. However, the crystalline phase of WO2 absorbs or scatters light in the visible light region, potentially reducing light absorption in the near-infrared region. Therefore, from the viewpoint of suppressing WO2 formation, the oxygen-to-tungsten ratio is preferably greater than 2:1.

[0066] Therefore, the oxygen-to-tungsten ratio z / y is preferably satisfied as described above: 2.2 ≤ z / y ≤ 3.3.

[0067] (2) Regarding the average particle size When using the composite tungsten oxide particles of this embodiment for applications requiring transparency, 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, thus maintaining high visibility in the visible light region while efficiently preserving transparency. In particular, when transparency in the visible light region is of paramount importance, it is preferable to further consider light scattering in the visible light region caused by the particles.

[0068] When it is important to reduce light scattering in the visible light region caused by these particles, the average particle size is more preferably 200 nm or less, and even more preferably 100 nm or less.

[0069] This is because if the average particle size is small, light scattering can be suppressed, which can suppress unintentional gloss in the visible light region and unintentional hue caused by wavelength-dependent light scattering (Rayleigh scattering).

[0070] Furthermore, if coarse particles are present during the process of incorporating the composite tungsten oxide particles of this embodiment into the fiber, there is a risk of yarn breakage during spinning. From this perspective, it is also preferable to reduce the particle size of the composite tungsten oxide particles.

[0071] Therefore, the average particle size of the composite tungsten oxide particles in this embodiment is preferably 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 in this embodiment is not particularly limited; for example, it is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more.

[0072] Based on the above reasons, the average particle size of the composite tungsten oxide particles is preferably 1 nm to 800 nm, more preferably 5 nm to 200 nm, even more preferably 10 nm to 200 nm, and particularly preferably 10 nm to 100 nm.

[0073] The average particle size of the composite tungsten oxide particles was determined and calculated by measuring the particle size of each composite tungsten oxide particle from transmission electron microscopy (TEM) images. Specifically, three fields of view were selected, each containing more than 200 composite tungsten oxide particles. The images of the composite tungsten oxide particles in each field of view were binarized, and the average particle size was calculated through image analysis. Furthermore, there is no particular upper limit on the number of composite tungsten oxide particles in one field of view; for example, a magnification level could be selected such that less than 500 composite tungsten oxide particles are contained in one field of view. Alternatively, all composite tungsten oxide particles in the three fields of view could be used as evaluation objects; for example, particles totaling between 500 and 800, or particles totaling between 600 and 700, could be selected from the total of the three fields of view.

[0074] Specifically, the diameter of a circle is calculated from the area of ​​each composite tungsten oxide particle and then used as the particle size. The particle sizes of all evaluated composite tungsten oxide particles are then summed and divided by the number of particles evaluated to calculate the average particle size. In other words, the arithmetic mean of the evaluated composite tungsten oxide particle sizes can be used as the average particle size.

[0075] (3) Contrast of atomic number (Z) of tungsten atoms in composite tungsten oxide particles In this embodiment, it is preferable that the composite tungsten oxide particles, in a STEM-HAADF image (STEM-High-Angle Annular Dark Field image) incident from

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

[001] is an image of the substrate surface of the composite tungsten oxide.

[0076] According to the inventors' research, composite tungsten oxide particles can particularly improve visible light transmittance and infrared shielding performance by having a moderate amount of trace oxygen defects that are difficult to detect through XRD patterns or the like.

[0077] Furthermore, since the composite tungsten oxide particles contain less than 10% tungsten atoms (hereinafter also referred to as "W atoms") in the dark areas of the Z-contrast, the W remaining around the W defect area can be oxidized, resulting in an oxygen defect amount within a reasonable range. Also, because the composite tungsten oxide particles contain more than 0.01% W atoms in the dark areas of the Z-contrast, oxygen defects can be moderately introduced.

[0078] The dark areas in the Z-contrast of W atoms in composite tungsten oxide particles represent the absence of W atoms. The dark areas caused by the Z-contrast of W atoms refer to spots (dots) where the Z-contrast of W atoms drops to less than 95% of the average Z-contrast of W atoms in the field of view of the STEM-HAADF image of composite tungsten oxide particles.

[0079] In STEM-HAADF image observation, particles that can be observed with incident light at

[001] and have a size of tens of nm or more can be selected from the dispersed composite tungsten oxide particles. Then, in order to extract the contrast of W atom spots, the size of the observation field can be made to be between 20 nm square and 50 nm square.

[0080] Figure 5 Displaying hexagonal Cs 0.33 The relationship between the crystal structure of the (001) plane of WO3 and the W atom / W atom column (hereinafter also referred to as "W / W column"). Figure 7A , Figure 7B Cs obtained in Example 1 is shown. 0.33 STEM-HAADF image of WO3 particles. Additionally... Figures 8A to 8F show Figure 7B The Z contrast of W atoms in the W atom / W atom column at lines L1 to L6 is shown.

[0081] The spots whose positions in the dark region of the Z-contrast of the W atom are confirmed, such as... Figure 7B The contrast weakens at points P1 and P2, indicating a deficiency of W atoms. Furthermore, in... Figure 7B In the diagram, the leading edge of the arrow marked with symbols such as P1 indicates the point in the aforementioned dark area.

[0082] The Z-contrast of W atoms can be obtained from images obtained by observing a sample using scanning transmission electron microscopy with high-angle scattering dark field (STEM-HAADF), where only electrons with large scattering angles are detected among the electrons passing through the sample (STEM-HAADF). Here, since the scattering angle is proportional to the square of the atomic number (Z), elements with larger atomic numbers exhibit brighter contrast. Therefore, contrast caused by differences in composition and elements can be obtained. Furthermore, in the case of composite tungsten bronze, the difference in contrast can be used to identify M elements such as Cs and W atoms.

[0083] In this embodiment, to distinguish between defective and non-defective W atoms, the difference in contrast intensity at tungsten pillars (W pillars) in the STEM-HAADF image, which are tungsten spots, is utilized. If W atoms are defective, the maximum Z contrast at that spot decreases. Hexagonal Cs 0.33 The W atom defect sites on the (001) facet of WO3 are displayed with a lower Z-contrast average than those at spots with W atom / W atom rows. These spots form defect regions of W atom extending in a columnar shape along the (001) direction. The largest sites extend beyond 10 nm in the (001) direction. No connected W atom defects beyond 5 nm were identified on the (001) facet.

[0084] The process of synthesizing composite tungsten oxide particles according to this embodiment will be used to explain the situation regarding the Z contrast of W atoms in the STEM-HAADF image of the composite tungsten oxide particles incident from

[001] .

[0085] Regarding the (001) plane of hexagonal composite tungsten oxide, the crystal structure will be explained. For example... Figure 5 As shown, an octahedron 54, formed by W atoms 51 and six O atoms 52, i.e., an octahedron 54 with O atoms at its vertices and W atoms 51 at its center, is assembled with six of them to form a hexagonal void (tunnel) 55 composed of O atoms 52. Furthermore, Figure 5 Circles with the same shaded line in the middle indicate that they are the same atoms.

[0086] Then, M element 53 is arranged to form a unit in the hexagonal void 55 composed of O atoms 52. Furthermore, this unit is aggregated in large quantities to form a hexagonal crystal structure. The hexagonal void 55 is parallel to the (001) plane. In addition, the (001) plane is perpendicular to the c-axis. By observing the (001) plane, the difference between M element 53 and W atom 51 can be distinguished from crystallographically.

[0087] As the composite tungsten oxide particles in this embodiment, Cs 0.33 Taking WO3 particles as an example, the changes in the crystal structure of the particles during the synthesis process are explained. The composite tungsten oxide particles of this embodiment, as described below, are manufactured through a raw material preparation process, an aerosol formation process, a heat treatment process, and a reduction treatment process. In the aerosol formation process, the aerosolized raw material is rapidly heated to above 500°C in the heat treatment process to undergo a reaction that transforms the raw material into composite tungsten oxide through short-term heating. Then, the heating is followed by rapid cooling to stop the reaction. The composite tungsten oxide particles obtained after the heat treatment process contain hexagonal crystals (Cs). 0.33 WO3) and Cs4W 11 O 35(Cs2O) 0.44 (WO6, etc.). STEM-HAADF images of the composite tungsten oxide particles confirm the presence of numerous W atom defects. These W atom defect sites become Cs-excess regions, contributing to the formation of heterogeneous phases.

[0088] The composite tungsten oxide particles containing heterogeneous phases obtained through a heat treatment process are subjected to a reduction treatment process without oxygen supply, during which Cs atoms, W atoms, and O atoms, which are elements of M, undergo rearrangement. This atomic rearrangement results in composite tungsten oxide particles exhibiting dark areas in the Z-contrast of W atoms observed in STEM-HAADF images incident from

[001] . Furthermore, the dark areas in the Z-contrast of W atoms in the STEM-HAADF images of the composite tungsten oxide particles obtained through the reduction treatment process are presumably traces of the aforementioned heterogeneous phase or W atom defects.

[0089] On the other hand, as shown in Comparative Example 1 described later, when synthesizing composite tungsten oxide particles under a reducing atmosphere for a longer time than in Example 1 without aerosolizing the raw materials, hexagonal single-phase composite tungsten oxide particles can be obtained by adjusting the atmosphere and heating conditions. The composite tungsten oxide particles prepared without aerosolizing the raw materials, as evaluated in Comparative Example 1, are... Figure 9B As shown, even when observing the STEM-HAADF image incident from

[001] , the dark areas in the Z contrast of W atoms are almost impossible to confirm.

[0090] In this embodiment, the composite tungsten oxide particles may also have a defect surface in a direction perpendicular to the c-axis in a STEM-HAADF image (prism surface) of the composite tungsten oxide particles incident from

[110] .

[0091] The aforementioned defect surfaces are caused by the loss of W atoms. Furthermore, sometimes there are spaces along the c-axis where M elements such as cesium and W atoms are absent.

[0092] Figure 12A , Figure 12B This is a STEM-HAADF image of the composite tungsten oxide particles involved in Example 1, incident from

[110] . Figure 12A In the study, a basal surface defect, namely defect surface 121, caused by a W atom defect of approximately 30 nm in length perpendicular to the c-axis direction, was confirmed. Additionally, a space 122 was confirmed where Cs atoms of approximately 3 nm in length along the c-axis direction are absent and where W atoms are not present.

[0093] Figure 12B yes Figure 12A The enlarged view shows the defect surface 121, which is a base surface defect, and the space 122 where Cs and W are absent along the c-axis direction. These are considered to be interface residues of the crystallization region when Cs and W atoms rearrange within the crystal during the heat treatment process.

[0094] Furthermore, a distorted structure with a 1 / 4 period shift in the crystal structure was confirmed to exist, with a defect surface 121 sandwiched between W atoms with a length of approximately 30 nm perpendicular to the c-axis. Figure 13 It is a schematic representation Figure 12A , Figure 12B A diagram showing the configuration of W and Cs atoms.

[0095] In the composite tungsten oxide particles of this embodiment, as described above, dark areas in the Z-contrast of W atoms in the STEM-HAADF image incident from

[001] were observed, presumably traces of W atom defects before the reduction treatment process. It can be confirmed that the composite tungsten oxide particles of this embodiment contain a large number of W atom defects before the reduction treatment process in the synthesis process. These W atom defect sites become Cs excess regions, which contribute to the formation of heterogeneous phases other than hexagonal crystals. Then, during the reduction treatment process, W atom rearrangement occurs, and when a hexagonal crystal structure is adopted, defect surfaces, i.e., defects on the substrate surface (001), are sometimes generated in the direction perpendicular to the c-axis. Due to the presence of these defects, it is believed that the rearrangement of W atoms to maintain the hexagonal crystal structure is carried out during the reduction treatment process. It is believed that during the rearrangement of W atoms in an attempt to maintain the hexagonal crystal, W atom defects (defect surfaces) are generated on the prism surfaces, maintaining the hexagonal crystal structure at the locations where no defects are generated.

[0096] As described above, in hexagonal composite tungsten oxide, theoretically, when z / y = 3, the value of x / y is 0.33, which is considered to represent the maximum amount of M element. Furthermore, x, y, and z in the above and following descriptions refer to x, y, and z in the general formula of the composite tungsten oxide particles described above. The molar ratio of M element to 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 molar ratio of M element is in the range of 0.20 ≤ x / y ≤ 0.37, then through the rearrangement of W atoms, even with defects on the prism facets, composite tungsten oxide particles with excellent infrared absorption characteristics can be produced while maintaining the hexagonal crystal structure. If the amount of M element is small, for example, x / y is less than 0.20, it is difficult to form a hexagonal crystal structure; even if a hexagonal crystal structure is formed, the number of free electrons supplied to the 5d orbitals of W atoms is small, resulting in poor infrared absorption characteristics.

[0097] On the other hand, when the molar ratio (x / y) of M to W is greater than 0.37, M is in excess. In addition to the prismatic faces, many W atoms will be missing on the substrate surface. Furthermore, in addition to hexagonal crystals, heterogeneous phases such as the pyrochlore phase will also be generated, resulting in poor infrared absorption characteristics. Such defects on the substrate surface are planar or banded defects with a length of more than 10 nm in the (001) direction.

[0098] According to the inventors' research, in the STEM-HAADF image (substrate plane image) of composite tungsten oxide particles with a molar ratio (x / y) of M element to W element greater than 0.37, incident from

[001] , band-shaped defects are observed. These band-shaped defects are planar defects of W atoms parallel to the c-axis. This phenomenon is caused by an excess of M atoms relative to W atoms. Due to the excess M atoms, in the process of W atom rearrangement, in addition to hexagonal crystals, heterogeneous phases such as pyrochlore are also generated. Furthermore, band-shaped W atom defects with a length exceeding 10 nm are also generated on the substrate surface of the composite tungsten oxide particles. It can be considered that once a W atom defect region with a length of more than 10 nm is formed, the defect region begins to form periodically, and heterogeneous phases such as pyrochlore are stabilized.

[0099] Furthermore, during the industrial synthesis of the composite tungsten oxide particles of this embodiment, the ratio of M element source to W element source may deviate in the raw material preparation process described later. In this case, the molar ratio (x / y) of some M elements and W elements may be greater than 0.37, and a portion of the resulting composite tungsten oxide particles may have band-shaped W atom defects with a length exceeding 10 nm on the substrate surface. However, if the proportion of particles with such defects is less than 20%, the infrared absorption characteristics will not deteriorate.

[0100] (4) XPS evaluation of composite tungsten oxide particles The W atoms in the infrared-absorbing composite tungsten oxide particles adopt W atoms due to oxygen vacancies. 5+ and W 6+ The electronic state. Then, by separating the intensity of the 4f orbital of the W atom in the XPS spectrum into those originating from W. 6+ and W 5+ The intensity of the oxidation state can be used to evaluate the oxidation state. As an example of the composite tungsten oxide particles of this embodiment, the composite tungsten oxide particles of Example 1, as confirmed by separating the XPS spectra, exhibit a further improvement in oxidation state compared to the composite tungsten oxide particles synthesized by the solid-state method listed in Comparative Example 1.

[0101] Figure 14A This is an XPS diagram of the W atom 4f distribution of the cesium tungsten composite oxide particles related to Example 1. Additionally, Figure 14B This is the XPS diagram of the W atom 4f distribution of the cesium tungsten composite oxide particles in Comparative Example 1.

[0102] In hexagonal cesium tungsten composite oxides, W 6+ It has 4f in the binding energy range of 34eV to 36eV. 7 / 2 The peak has a 4f value in the binding energy range of 36 eV to 38 eV. 5 / 2 The peak. W5+ It has 4f in the binding energy range of 32eV to 34eV. 7 / 2 The peak exhibits 4f in the binding energy range of 35 eV to 37 eV. 5 / 2 The peak.

[0103] Based on this knowledge, W4f 7 / 2 and W4f 5 / 2 With the peak spacing fixed at 2.18 eV and the peak area ratio fixed at 0.75, the measured distribution plot was fitted using the least squares method with a Gaussian or Lorentz distribution, thus enabling peak separation in XPS. By knowing W... 5+ W of XPS 6+ With W 5+ The intensity ratio of the total intensity indicates the oxidation state of the W atoms in the composite tungsten oxide particles. Furthermore, during peak separation, the background of the distribution map was removed, allowing for the identification of W4f atoms. 7 / 2 and W4f 5 / 2 The half-peak widths are consistent.

[0104] The composite tungsten oxide particles involved in Example 1 account for W 6+ With W 5+ Total strength W 5+ The proportion was 24.9%, while that of the composite tungsten oxide particles involved in Comparative Example 1 was 25.96%. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) 6+ With W 5+ Intensity separation, Figure 14A The distribution diagram shown indicates the composite tungsten oxide particle ratio of Example 1. Figure 14B The W of the composite tungsten oxide particles shown in Comparative Example 1 5+ The proportion is small, that is, W 6+ A higher proportion of oxidation indicates further oxidation.

[0105] In Example 1, W 5+ The reason for the reduced oxidation is speculated to be because, for example Figure 7A , Figure 7B or Figure 12A , Figure 12B As shown, due to the presence of W defects formed along the c-axis or the base plane, W atoms in the crystal are stabilized by combining with oxygen.

[0106] While the above example is just one instance, as mentioned earlier, the composite tungsten oxide particles of this embodiment can be manufactured by aerosolizing the raw materials and then subjecting them to heat treatment or similar processes. Composite tungsten oxide particles manufactured using this method, which involves aerosolizing the raw materials, tend to oxidize more readily than composite tungsten oxide particles obtained through conventional solid-state synthesis, pulverization, or similar methods.

[0107] (5) Peak separation and integrated intensity of local surface plasmon absorption and polaron absorption of composite tungsten oxide particles In the composite tungsten oxide particles of this embodiment, the oxidation state affects the optical properties. The molar absorptivity curve was studied based on the absorbance curves measured by a spectrophotometer of the dispersion of the composite tungsten oxide particles. The absorption in the absorbance curve is due to localized surface plasmon absorption and polaron absorption of the particles; the combination of these absorptions results in the absorbance curve.

[0108] In the case of composite tungsten oxide, localized surface plasmon absorption exhibits anisotropy relative to the c-axis. Specifically, in the case of composite tungsten oxide particles, localized surface plasmon absorption includes absorption of localized surface plasmon resonance perpendicular to the c-axis (LSPR⊥) and absorption of localized surface plasmon resonance parallel to the c-axis (LSPR / / ).

[0109] That is, in composite tungsten oxide particles, there are three absorption elements: absorption caused by local surface plasmon resonance perpendicular to the c-axis (vertical direction) (LSPR⊥), absorption caused by local surface plasmon resonance parallel to the c-axis (parallel direction) (LSPR / / ), and polaron absorption. Therefore, the molar absorptivity curve of composite tungsten oxide particles can be separated into three absorption curves.

[0110] Specifically, the horizontal wavelength of the molar absorptivity curve is converted to energy (eV), and the molar absorptivity curve is fitted with Gaussian and Lorentz distributions based on Mie scattering theory. Then, the absorption curves are separated into absorption curves caused by local surface plasmon resonance perpendicular to the c-axis (LSPR⊥), absorption curves caused by local surface plasmon resonance parallel to the c-axis (LSPR / / ), and absorption curves of polaron absorption.

[0111] In the separation of molar absorptivity curves, by obtaining the absorption curves of absorption caused by local surface plasmon resonance perpendicular to the c-axis (LSPR⊥), absorption curves of absorption caused by local surface plasmon resonance parallel to the c-axis (LSPR / / ), and absorption curves of polaron absorption, the average value of the Gaussian or Lorentz distribution (which becomes the energy (wavelength) of the peak value) can be determined. Each Gaussian distribution is represented by equation (1).

[0112]

Number 1

[0113] The Lorentz distribution is represented by the following equation (2).

[0114]

Number 2

[0115] The results of separating absorption curves at wavelengths above 0.5 eV and below 2.0 eV (wavelengths above 620 nm and below 2500 nm) using these functions are as follows: Figure 15A , Figure 15B As shown. In addition, the near-infrared region (wavelength above 780nm and below 2500nm) is 0.5eV to 1.59eV.

[0116] Figure 15A The display shows the molar absorptivity curve of the composite tungsten oxide particles in Example 1, which is an example of composite tungsten oxide particles in this embodiment. Additionally, Figure 15B The table shows the molar absorptivity curves of the composite tungsten oxide particles in Comparative Example 1, which is an example of composite tungsten oxide particles synthesized and pulverized using a conventional solid-state method. Table 2 shows the peak positions, peak intensities, and integral intensities of the absorption curves for the three absorption elements. Furthermore, Table 3 shows the ratio of the integral intensities of the absorption curves for the three absorption elements to the integral intensities of the molar absorptivity curve.

[0117] Figure 15A , Figure 15B This is one example; the molar absorptivity curves in each figure are illustrative and not limited to these molar absorptivity curves. However, the composite tungsten oxide particles of this embodiment show similarities to... Figure 15A The molar absorptivity curve shown exhibits the same tendency.

[0118] Figure 15A The absorption peak in the absorption curve of the localized surface plasmon resonance (LSPR⊥) perpendicular to the c-axis in the composite tungsten oxide particles of Example 1 is 0.86 eV (wavelength 1435 nm), and the integrated intensity of the absorption curve is 96015.38 [L·eV / (mol·cm)].

[0119] exist Figure 15A In the molar absorptivity curve shown, the absorption peak of the local surface plasmon resonance (LSPR / / ) absorption curve parallel to the c-axis is 1.20 eV (wavelength 1030 nm), and the integrated intensity of this absorption curve is 33042.00 [L·eV / (mol·cm)].

[0120] exist Figure 15A In the molar absorptivity curve shown, the absorption peak of 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)].

[0121] exist Figure 15A Of the three absorption curves shown in the molar absorptivity curves, the proportion of the integral intensity of the polaron absorption curve is 8.7%. The composite tungsten oxide particles of Example 1 were synthesized by aerosolization followed by heat treatment, etc., and the integral intensity of polaron absorption was reduced compared with composite tungsten oxide particles synthesized by conventional solid-state methods.

[0122] on the other hand, Figure 15B The display shows the molar absorptivity curve of the composite tungsten oxide particles of Comparative Example 1, synthesized and pulverized using a previously known solid-state method. Figure 15B In the molar absorptivity curve shown, the absorption peak of the local surface plasmon resonance (LSPR⊥) absorption curve perpendicular to the c-axis is 0.80 eV (wavelength 1550 nm), and the integrated intensity of this absorption curve is 78843.30 [L·eV / (mol·cm)].

[0123] exist Figure 15B In the molar absorptivity curve shown, the absorption peak of the local surface plasmon resonance (LSPR / / ) absorption curve 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)].

[0124] exist Figure 15B In the molar absorptivity curve shown, the absorption peak of the polaron absorption curve is 1.40 eV (wavelength 885 nm), and the integral intensity of the absorption curve is 31174.01 [L·eV / (mol·cm)].

[0125] exist Figure 15B Of the three absorption curves shown in the molar absorptivity curve, the proportion of the integral intensity of the polaron absorption curve is 23.9%.

[0126] A comparison of the integrated intensity ratios of the polaron absorption curves above clearly shows that the composite tungsten oxide particles of Example 1 exhibit weaker polaron absorption than those of Comparative Example 1. This is also evidenced by the fact that the peak value of the polaron absorption curve of the composite tungsten oxide particles of Example 1 at 1.26 eV (wavelength 985 nm) is weaker than the peak value of the polaron absorption curve of the composite tungsten oxide synthesized by the solid-state method at 1.40 eV (wavelength 885 nm).

[0127] Furthermore, the composite tungsten oxide particles of Example 1 exhibit absorption induced by localized surface plasmon resonance, meaning the proportions of the integrated intensities of the absorption curves for LSPR⊥ and LSPR / / are significantly increased. In particular, the proportion of the integrated intensity of the LSPR / / absorption curve in the composite tungsten oxide particles of Example 1, synthesized and pulverized by the solid-state method, is greater than that in the composite tungsten oxide particles of Comparative Example 1. These differences in absorption states manifest in optical properties.

[0128] Here, the integrated intensities of the three absorption curves are those between 0.5 eV and 2.0 eV (wavelengths between 620 nm and 2500 nm). By comparing the integrated intensities of the three absorption elements—local surface plasmon resonance (LSPR⊥) perpendicular to the c-axis, local surface plasmon resonance (LSPR / / ) parallel to the c-axis, and polaron absorption—in the aforementioned range, the contributions of these three absorption elements in the near-infrared region (wavelengths between 780 nm and 2500 nm) can be understood.

[0129] Furthermore, starting from the low-energy side, absorption peaks appear sequentially, including localized surface plasmon resonance perpendicular to the c-axis, localized plasmon absorption parallel to the c-axis, and polaron absorption. That is, polaron absorption occurs in the high-energy region (short-wavelength side in the near-infrared region).

[0130] It is known that the absorption caused by polarons in composite tungsten oxide particles is due to the W atoms in the crystal that make up the particles. 5+ Caused by. As shown in the XPS results above, the composite tungsten oxide particles of this embodiment are due to W caused by oxygen deficiency. 5+ The proportion of polaron absorption is less than that of previously known composite tungsten oxide particles when performing peak separation of the molar absorptivity curve.

[0131] The composite tungsten oxide particles of this embodiment exhibit sharp infrared absorption near a wavelength of 1000 nm because the integrated intensity or peak value of the absorption curve of localized surface plasmon absorption parallel to the c-axis is higher than that of polaron absorption. In other words, the composite tungsten oxide particles of this embodiment have weak light absorption near a wavelength of 800 nm due to polaron absorption, but possess the effect of absorbing infrared light near a wavelength of 1000 nm. In contrast, conventionally known composite tungsten oxide particles synthesized by solid-state methods, such as... Figure 15BAs shown, the integrated intensity or peak value of the absorption curve of polaron absorption is higher than that of the absorption curve of localized surface plasmon absorption parallel to the c-axis. This difference is reflected in the hue of the transmitted light; according to the composite tungsten oxide particles of this embodiment, when prepared into a dispersion or mixture, the transmitted light can be made into a neutral hue. Furthermore, the composite tungsten oxide particles of this embodiment exhibit excellent visible light transmittance and near-infrared shielding properties.

[0132] Furthermore, the molar absorptivity of the powder composed of composite tungsten oxide particles in the dispersion can be obtained from the molar absorptivity curve. The molar absorptivity of the powder composed of composite tungsten oxide particles in this embodiment is preferably 2600 L / (mol·cm) or more, and more preferably 2800 L / (mol·cm) or more.

[0133] Previously known composite tungsten oxide particles could also have their absorption curve peaked lower than that of localized surface plasmon absorption parallel to the c-axis by adjusting the manufacturing conditions.

[0134] However, if the peak value of the absorption curve of polaron absorption in previously known composite tungsten oxide particles is lower than the peak value of the absorption curve of localized surface plasmon absorption parallel to the c-axis, the molar absorptivity will be less than 2000 L / (mol·cm). A high molar absorptivity is ideal in infrared absorbing materials, allowing for excellent infrared shielding even with a small amount of material.

[0135] Based on the crystal structure and electronic state of composite tungsten oxide, the composite tungsten oxide particles of this embodiment can be made with superior infrared absorption capabilities compared to the composite tungsten oxide particles synthesized and pulverized by a conventional solid-state method as illustrated in Comparative Example 1.

[0136] The composite tungsten oxide particles of this embodiment can impart infrared absorption functionality to the fiber by being disposed at one or more positions selected from the inside and surface of the fiber.

[0137] Regarding the dispersion of the composite tungsten oxide particles of this embodiment in a solvent, when the transmittance distribution is measured by a spectrophotometer, even with a transmittance peak of 75% or more in the region of wavelengths between 500 nm and 600 nm, the transmittance trough in the near-infrared region remains below 5%. In other words, the composite tungsten oxide particle dispersion of this embodiment exhibits excellent infrared shielding effect (infrared absorption effect). Therefore, regarding the infrared-absorbing fibers and fiber products of this embodiment, the amount of composite tungsten oxide particles required to prevent unauthorized photography using CCD cameras or other imaging devices can be reduced compared to the use of conventionally known composite tungsten oxide particles.

[0138] Furthermore, the dispersion of composite tungsten oxide particles in this embodiment, compared to the dispersion of composite tungsten oxide particles shown in Comparative Example 1, can also transmit red light with a wavelength around 800 nm. Therefore, it also helps to improve the hue of infrared absorbing fibers using composite tungsten oxide particles.

[0139] [Manufacturing method of composite tungsten oxide particles] This document outlines the method for manufacturing the composite tungsten oxide particles according to this embodiment.

[0140] The method for manufacturing composite tungsten oxide particles according to this embodiment can produce the previously described composite tungsten oxide particles, therefore the explanation of the already described matters is omitted. Furthermore, only a configuration example of the method for manufacturing composite tungsten oxide particles is shown here, and the method for manufacturing composite tungsten oxide particles described herein is not limited to the following configuration example.

[0141] The method for manufacturing composite tungsten oxide particles in this embodiment is preferably a method that can directly synthesize composite tungsten oxide particles with a particle size of less than 1 μm. If composite tungsten oxide particles with a particle size of less than 1 μm can be directly synthesized, particles with minimal impact from pulverization or dispersion damage can be obtained, such as composite tungsten oxide particles with a particle size of less than 800 nm.

[0142] A preferred method for directly synthesizing composite tungsten oxide particles with a particle size of less than 1 μm is a manufacturing method that synthesizes particles by supplying a raw material aerosol containing an M element source and a tungsten element source to an electric furnace, flame, or plasma for heat treatment.

[0143] Therefore, the method for manufacturing composite tungsten oxide particles in this embodiment may include the following raw material preparation process, aerosol formation process, heat treatment process, and reduction treatment process.

[0144] In the raw material preparation process, raw materials containing M element source and tungsten element source can be prepared.

[0145] In the aerosol formation process, the raw materials prepared in the raw material preparation process can be aerosolized.

[0146] In the heat treatment process, the aerosolized raw materials can be heat-treated in the reaction field.

[0147] In the reduction process, the particles obtained in the heat treatment process can be reduced in an atmosphere containing reducing gas.

[0148] (1) Regarding each process The following describes each step of the method for manufacturing composite tungsten oxide particles according to this embodiment.

[0149] (1-1) Raw material preparation process In the raw material preparation process, raw materials containing M element source and tungsten element source (hereinafter also referred to as "W element source") can be prepared.

[0150] In the raw material preparation process, the raw materials can be mixed and prepared so that the ratio of the amount of element M to the amount of element W in the raw materials corresponds to the composition of the target composite tungsten oxide particles.

[0151] The state of the raw materials used in the raw material preparation process is not particularly limited; they can be liquids or powders, but preferably capable of forming aerosols through spraying or other means. Furthermore, an aerosol refers to a mixture of tiny liquid or solid particles suspended in a gas and the surrounding gas.

[0152] When the raw material is liquid, it can be prepared, for example, by preparing a solution containing M element source and W element source.

[0153] Alternatively, a solution containing the M element source and a solution containing the W element source can be prepared separately in advance, and the two solutions can be mixed in the raw material preparation process to form a raw material mixture solution.

[0154] The heat treatment process described later can also involve supplying the raw material in the form of droplets. In this case, the raw material preparation process can be performed by mixing a solution containing an element M source and a solution containing an element W source before the raw material is supplied to the droplet forming unit (droplet forming means) that forms the droplets, or within the droplet forming unit. Then, the aerosol forming process described later can be performed in the droplet forming unit.

[0155] For example, when pre-mixing a solution containing an element M source and a solution containing an element W source, problems such as gelation may occur. In this case, it is preferable to prepare the two solutions in advance as described above and mix them before the aerosol formation step. When performing the raw material preparation step before the aerosol formation step, the molar ratio of element M and element W in the raw material can be adjusted to the desired range by adjusting the concentration of the two solutions and the feeding rate of the two solutions to the droplet forming section.

[0156] As mentioned above, when the raw material preparation process is performed before the aerosol formation process, the aerosol formation process and the raw material preparation process do not need to be clearly distinguished, and the two processes can be performed consecutively.

[0157] As mentioned above, in the raw material preparation process, when mixing a solution containing an M element source and a solution containing a W element source, there is no particular limitation on the specific mixing method, and any method can be used.

[0158] There are no particular limitations on the source of tungsten (W), as long as it is a raw material containing tungsten, such as elemental tungsten or tungsten compounds. Tungsten salts can be used as the W source; for example, tungsten hexacarbonyl is preferred. Tungsten hexacarbonyl can be represented as W(CO)6, for example. Furthermore, considering ease of handling, organic solutions containing the W source are preferred as the solution.

[0159] There are no particular limitations on the source of element M; any raw material containing element M is acceptable, including elemental M and compounds containing element M. For example, a solution containing a salt of element M can be used as the source of element M. There are no particular limitations on the type of salt of element M used as the source of element M; for example, one or more salts selected from carbonates, acetates, nitrates, hydroxides, etc., containing element M can be used.

[0160] From the perspective of ease of operation, an ethanol solution containing the M element source is preferred as the solution containing the M element source.

[0161] For example, even when the element M is cesium, although more than one salt selected from carbonates, acetates, nitrates, hydroxides, etc., can be used as the salt source of element M, acetate is particularly preferred. This is because cesium acetate is particularly soluble in ethanol.

[0162] Furthermore, the proportion of M element relative to 1 mole of tungsten in the resulting composite tungsten oxide, i.e., the doping amount, is determined by the ratio of W element source to M element source when forming the raw material mixed solution. Therefore, the doping amount can be controlled, for example, by the solution concentration containing the W element source and the solution concentration containing the M element source.

[0163] The concentration of the W element source in the solution, i.e., the concentration of W element salts, is not particularly limited. For example, the tungsten concentration in the solution containing the W element source is preferably 0.001 mol / L to 10 mol / L, more preferably 0.01 mol / L to 10 mol / L, and even more preferably 0.01 mol / L to 1 mol / L. This is because by ensuring the tungsten concentration in the solution containing the W element source is 0.001 mol / L or higher, the production rate of composite tungsten oxide particles per unit time can be sufficiently ensured, for example, by recovering a sufficient amount through filters, thereby improving productivity. In addition, by ensuring the tungsten concentration in the solution containing the W element source is 10 mol / L or lower, the redeposition of dissolved W element source can be suppressed, and particle aggregation can be suppressed, for example, the mixing of coarse composite tungsten oxide particles with a particle size greater than 1 μm can be suppressed. Furthermore, additives such as pH-adjusting agents and surfactants can be added to the solution containing the W element source.

[0164] Furthermore, the concentration of the M element source in the solution containing the M element source is not particularly limited, and can be selected based on the desired composition of the manufactured composite tungsten oxide particles, the concentration of the W element source in the solution containing the W element source, and so on.

[0165] In addition to solutions containing W element sources and solutions containing M element sources, any other components may be added to the raw material mixture solution.

[0166] So far, the example given is that the raw material is a liquid, but the raw material can also be a solid, such as a powder. When the raw material is a powder, it can be prepared, for example, by mixing powder of an element M compound and powder of a tungsten compound. Alternatively, for example, tungsten compound powder can be added to a solution containing an element M source and stirred, and a precursor powder whose solvent has been removed by drying or the like can be used as the raw material.

[0167] When the raw material is solid, there are no particular limitations on the source of W element, and tungsten salts can be used, such as H2WO4 and ammonium paratungstate.

[0168] In H2WO4, the elements other than tungsten are H (hydrogen) and O (oxygen). These elements are removed from the system during the heat treatment process described later. Therefore, by using H2WO4 as the W element source, composite tungsten oxide particles with suppressed impurity contamination can be obtained, making it a preferred choice.

[0169] As a source of element M, powdered salts containing element M can be used, for example. The type of salt containing element M is not particularly limited; for example, one or more salts selected from elements M, such as carbonates, acetates, nitrates, and hydroxides, can be used.

[0170] For example, when the element M is cesium, although one or more of the following can be used: carbonate, acetate, nitrate, hydroxide, etc., carbonate is particularly preferred.

[0171] (1-2) Aerosol Formation Process In the method for manufacturing composite tungsten oxide particles according to this embodiment, it is preferable to prepare the raw materials prepared in the raw material preparation step into an aerosol state and supply it to the heat treatment step. Specifically, it is preferable to transport the aerosol through a carrier gas such as oxygen to the heat treatment step.

[0172] Therefore, the method for manufacturing composite tungsten oxide particles according to this embodiment may include an aerosol forming step of preparing an aerosol containing raw material droplets or particles.

[0173] There are no particular limitations on the means and methods for forming aerosols in the aerosol formation process; they can be selected based on the state of the raw materials.

[0174] When the raw material is liquid, an aerosol can be formed by spraying the liquid raw material into the carrier gas using various atomizers such as centrifugal atomizers or dual-fluid nozzles. Alternatively, droplets can be formed by irradiating the liquid with ultrasound.

[0175] When the raw material is powder, a dispersed state of the raw material powder can be formed, and an aerosol can be formed by supplying the powder to a gas stream. For example, an aerosol forming device can be used, which includes a stirring section with rotating brushes or stirring blades, and a powder supply section such as a piston or screw feeder that feeds the raw material to the stirring section. The raw material powder supplied from the powder supply section is dispersed into particles constituting the powder in the stirring section, and an aerosol can be generated from the raw material powder by sending each particle into a carrier gas. In order to disperse the raw material powder into particles, the rotation speed of the brush or stirring blades in the stirring section can be selected, and it is preferable to rotate at a high speed.

[0176] When forming droplets dispersed in the gas during 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 keeping the droplet diameter to 100 μm or less, coarsening of the resulting composite tungsten oxide particles can be prevented, and nanoscale composite tungsten oxide particles can be obtained. Furthermore, there is no particular limitation on the lower limit of the droplet size formed in the aerosol forming process. However, forming droplets that are too small is difficult and may reduce productivity; for example, a size of 1 μm or more is preferred.

[0177] When forming solid particles dispersed in the gas during the aerosol forming 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 making the particle diameter 100 μm or less, heat treatment can be performed more precisely inside the particles. The particle diameter can be measured in the same way as the particle size of the previously described composite tungsten oxide particles.

[0178] (1-3) Heat treatment process In the heat treatment process, raw materials can be processed into composite tungsten oxide particles through heat treatment. Heat treatment can be performed on the raw materials at a temperature above 500°C, and the composition of the heat source is not particularly limited. Therefore, the heat treatment process can be carried out by introducing the raw materials into a flame using a carrier gas, into a tubular electric furnace, or by introducing plasma. Regardless of whether a flame, electric furnace, or plasma is used, the heat treatment temperature can be set above 500°C. By heat treatment at temperatures above 500°C, the compounds contained in the raw materials decompose, and tungsten reacts with element M to form composite tungsten oxide.

[0179] Since the composite tungsten oxide particles obtained after the heat treatment process contain appropriate W atom defects or heterogeneous phases, composite tungsten oxide particles with Z-contrast dark areas containing W atoms can be obtained after the reduction treatment process. Therefore, conditions such as the heat treatment temperature can be selected to produce composite tungsten oxide particles with appropriate W atom defects or heterogeneous phases after the heat treatment process, and to produce composite tungsten oxide particles with confirmed W atom Z-contrast reduction spots after the reduction treatment process. For this purpose, in order to include W atoms in the Z-contrast dark areas at a desired proportion after the reduction treatment process, it is preferable to conduct preliminary experiments to select the raw material supply rate, heat treatment temperature, etc., in the heat treatment process. Furthermore, the heat treatment temperature and other conditions are preferably selected to reduce or remove heterogeneous phases after the reduction treatment process.

[0180] The heat treatment temperature only needs to be sufficient to allow the reaction between tungsten and element M to occur; therefore, 500°C or higher is acceptable, but 550°C or higher is preferred, and 1000°C or higher is even more preferred. There is no particular upper limit to the heat treatment temperature, but from the viewpoint of minimizing energy consumption, 4000°C or lower is preferable.

[0181] In the heat treatment process, as described above, a flame can be used to heat-treat the raw materials. By adjusting the temperature of the flame reaction field during the heat treatment process, the particle size of the resulting composite tungsten oxide particles can be selected.

[0182] In the case where liquid feedstock is sprayed into a carrier gas to form droplets, and this feedstock is introduced into a flame to synthesize composite tungsten oxide particles, the feedstock droplets move within the flame via a carrier gas such as oxygen. Once the feedstock droplets are delivered into the flame, an organic solvent containing the tungsten source and the M element source burns, and the solvent is decomposed through the combustion reaction. The heat generated by the combustion reaction facilitates the decomposition of tungsten and the M element, which precipitate out during cooling at the flame tail.

[0183] For example, as mentioned earlier, tungsten hexacarbonyl can be used as a W source, and cesium acetate can be used as a M source if the M element is cesium. These salts decompose during the heat treatment process. In this case, W easily precipitates as WO6, while Cs, as a monomer, is difficult to form oxides. Some of the Cs cannot precipitate as nano-sized powder and is discharged from the system through the filter.

[0184] Then, under the above conditions, during the decomposition of the solute portion, tungsten reacts with element M to form composite tungsten oxide.

[0185] When using a flame in a heat treatment process, there are no particular limitations on the flame formation conditions. For example, a mixture of gases containing oxygen and hydrocarbons can be used to form the flame. By forming a flame using a mixture of gases containing oxygen and hydrocarbons, a temperature-stable flame can be formed, resulting in composite tungsten oxide particles with suppressed deviations in particle size and other characteristics.

[0186] There are no particular limitations on the method for adjusting the flame size and flame temperature. For example, it is preferable to adjust the flow rates of the two gases while ensuring that the flow ratio of oxygen to combustible gases such as hydrocarbons in the gas mixture supplied to the flame is a flow ratio that enables combustion of combustible gases. This is because the firepower can be adjusted while ensuring the amount of oxygen required for combustion of combustible gases.

[0187] For example, when using a mixture of oxygen and propane to form a flame, the preferred flow-volume ratio of propane to oxygen in the mixture is 1 part propane to 5 parts oxygen and 8 parts oxygen, with the propane flow rate in the range of 0.5 L / min to 2 L / min. This is because when the propane flow rate is 1, the combustion of propane as a combustible gas can be sufficiently promoted by making the oxygen flow rate 5 parts or more. However, in order to avoid an oversupply of oxygen, it is preferable to supply 8 parts or less oxygen relative to 1 part propane.

[0188] The heat treatment temperature, such as that in a flame reaction field, also affects the particle size of the resulting composite tungsten oxide particles.

[0189] This is speculated because the sublimation of the generated composite tungsten oxide particles utilizes thermal energy from reaction fields such as flames, and fine-sized particles are obtained through the splitting of sublimated particles.

[0190] The composite tungsten oxide particles obtained after heat treatment can be recovered, for example, using a filter.

[0191] (1-4) Reduction Process The particles obtained after heat treatment, specifically composite tungsten oxide particles, sometimes do not exhibit infrared absorption characteristics. Therefore, the inventors of this invention conducted research and discovered that by further subjecting the heat-treated composite tungsten oxide particles to a reduction treatment process, the composite tungsten oxide particles can exhibit infrared absorption characteristics.

[0192] Therefore, the method for manufacturing composite tungsten oxide particles according to this embodiment may include a reduction treatment step in which the particles obtained in the heat treatment step are reduced under an atmosphere containing a reducing gas. Specifically, for example, the method for manufacturing composite tungsten oxide particles according to this embodiment may include a reduction treatment step in which, after the heat treatment step, the particles are reduced under an atmosphere containing a reducing gas at a temperature in the range of 400°C to 700°C.

[0193] The conditions for reduction treatment are not particularly limited, but it is preferable to select conditions that ensure the crystal structure of the reduced-treated composite tungsten oxide particles remains unchanged before and after the reduction treatment process, and that no metallic tungsten or the like precipitates, when analyzed by X-ray diffraction patterns. Furthermore, it is also preferable to select conditions that ensure the reduced-treated composite tungsten oxide particles contain the dark areas of the Z-contrast of W atoms in the desired proportion.

[0194] In the reduction process, the composite tungsten oxide particles obtained in the heat treatment process can be reduced by heating and cooling them in a reducing atmosphere containing reducing gas.

[0195] During the reduction process, the composite tungsten oxide particles can be stirred or left to stand. The treatment of the composite tungsten oxide particles in the reduction process can be appropriately selected, but it is preferred to select treatment conditions that do not precipitate metallic tungsten.

[0196] The reduction treatment temperature is preferably above 400°C, more preferably above 450°C, and even more preferably above 500°C.

[0197] There is no particular limit to the upper limit of the temperature for the reduction process. For example, it is preferred to be below 700°C, more preferably below 650°C, and even more preferably below 650°C.

[0198] Furthermore, when the raw material is liquid, reducing the raw material concentration during the aerosol formation process results in smaller particle sizes. Smaller particles are easier to reduce, thus allowing for a lower temperature in the reduction process. In the reduction process, the temperature can be raised from room temperature to the reduction temperature and then cooled back to room temperature.

[0199] The reduction conditions can be determined based on the optical properties of the obtained composite tungsten oxide particles.

[0200] By setting the reduction treatment temperature above 400°C, the reduction of the composite tungsten oxide particles is accelerated, allowing for a more accurate expression of their infrared absorption properties. Conversely, by setting the temperature below 700°C, the reduction of the composite tungsten oxide particles to metallic tungsten can be suppressed.

[0201] The reducing atmosphere is preferably a mixture of inert gases such as argon and reducing gases such as H2 (hydrogen), with H2 being the preferred reducing gas.

[0202] When using H2 gas as the reducing gas, the H2 gas content in the reducing atmosphere can be appropriately selected, but the H2 gas content, by volume percentage, is preferably in the range of 0.1% to 10%, more preferably in the range of 2% to 10%. If reduction is carried out in an atmosphere containing only the reducing gas, the reduction reaction will proceed excessively, which may result in the precipitation of metallic tungsten; therefore, caution is required.

[0203] The reduction treatment process, from heating to cooling, is expected to take at least 30 minutes. There is no particular upper limit to the reduction treatment time; for example, preliminary tests are preferred to avoid excessive reduction. Furthermore, the total time from heating to cooling refers to the time from heating at room temperature to reaching the reduction treatment temperature and then cooling back to room temperature. Preferably, the composite tungsten oxide particles are placed in the aforementioned reducing atmosphere during this time.

[0204] By implementing a reduction process in this way, the non-target heterogeneous phase in the composite tungsten oxide particles obtained after the heat treatment process can be converted into the target composite tungsten oxide phase.

[0205] (2) Apparatus applicable to the manufacturing method of composite tungsten oxide particles (2-1) Composite material manufacturing equipment The following description is an example of the configuration of a composite material manufacturing apparatus applicable to the method for manufacturing composite tungsten oxide particles according to this embodiment.

[0206] Figure 1 This is a schematic diagram illustrating the composite material manufacturing apparatus 10 of this embodiment.

[0207] The composite material manufacturing apparatus 10 includes a storage section 11 for holding a solution as raw material, a two-fluid nozzle 12 for forming raw material droplets and simultaneously forming a flame, and a reaction tube 13 connected to a filter 14 for recovering the formed composite tungsten oxide particles. As described above, the raw material solution can include a solution containing both an M element source and a W element source.

[0208] Supplying a raw material solution and carrier gas to the dual-fluid nozzle 12 can form an aerosol (aerosol formation process). For example, supplying oxygen and hydrocarbons to the dual-fluid nozzle 12 also creates a flame reaction field; the resulting aerosol is then supplied to the flame for heat treatment (heat treatment process). Cooling water piping 131 is arranged around the reaction tube 13, and the cooling water is circulated. The composite tungsten oxide particles introduced into the reaction tube 13 are recovered through a filter 14, such as a bag filter.

[0209] In addition, an injector 15 can be installed on the downstream side to adjust the supply of carrier gas.

[0210] While this example demonstrates a composite material apparatus for forming raw material droplets, heat treatment using a flame, and forming composite tungsten oxide particles, it is not limited to this form. The raw material can also be powder, and the heat source for heat treatment can be an electric furnace, etc.

[0211] (2-2) Reduction treatment device The reduction process described above can be performed in the reduction processing apparatus.

[0212] The reduction processing apparatus is not particularly limited as long as it is configured to perform the described reduction processing steps. For example, it may be equipped with a container for storing the particles, i.e., composite tungsten oxide particles, obtained from the described composite material manufacturing apparatus, a gas pipeline for supplying a mixed gas as a reducing atmosphere into the container, and a heat source for heating the container.

[0213] Alternatively, a mixed gas serving as a reducing atmosphere can be introduced into and discharged into the container, and the composite tungsten oxide particles to be treated can be placed under the gas flow of this mixed gas. In this case, in order to form this gas flow, a supply pipe and an exhaust pipe for the mixed gas can be installed as gas piping.

[0214] Alternatively, it can be used with stirring blades containing composite tungsten oxide particles in a stirring container.

[0215] Figure 2 This is a schematic diagram illustrating one configuration example of a reduction processing apparatus, showing a cross-sectional view of the plane passing through the central axis of the reaction tube 21 of the reduction processing apparatus 20.

[0216] The reduction processing apparatus 20 is a horizontal tubular furnace. A gas inlet pipe (not shown) can be installed at one port 21A of the reaction tube 21, and a gas exhaust pipe (not shown) can be installed at the other port 21B of the tubular furnace. Then, by supplying a mixed gas as a reducing atmosphere from one port 21A side, the reaction tube 21 can be made into a reducing atmosphere.

[0217] A heater 22 can be installed around the reaction tube 21. Composite tungsten oxide particles are placed in a ceramic container 23 such as a boat, which can be positioned inside the tubular furnace reaction tube 21 corresponding to the heater 22.

[0218] Using the reduction treatment device 20, the reaction tube 21 is filled with a reducing atmosphere, and the composite tungsten oxide particles 24 placed in the container 23 can be reduced by heating them to the desired temperature through the heater 22.

[0219] [Infrared Absorbing Particle Dispersion] Next, an example of the composition of an infrared absorbing particle dispersion that can be used in manufacturing the infrared absorbing fiber of this embodiment will be described.

[0220] The infrared absorbing particle dispersion of this embodiment may contain infrared absorbing particles and a liquid medium. Furthermore, the previously described composite tungsten oxide particles can be used as the infrared absorbing particles.

[0221] As a liquid medium, one or more selected from water, organic solvents, oils, liquid resins, and liquid plasticizers can be used. That is, for example, Figure 3 As shown, the infrared absorbing particle dispersion 30 of this embodiment may include infrared absorbing particles 31 and a liquid medium 32. Preferably, the infrared absorbing particle dispersion has a configuration in which the infrared absorbing particles are dispersed in the liquid medium.

[0222] also, Figure 3 This is a schematic diagram; the infrared-absorbing particle dispersion of this embodiment is not limited to this form. For example, in Figure 3 The mid-infrared absorbing particles 31 are represented by circles and described as spherical particles, but the shape of the composite tungsten oxide particles, i.e., the infrared absorbing particles 31, is not limited to this shape and can have any shape. The infrared absorbing particles 31 may also have a coating layer on their surface, for example. In addition to the infrared absorbing particles 31 and the liquid medium 32, the infrared absorbing particle dispersion 30 may also contain other additives as needed.

[0223] As a liquid medium, as mentioned above, one or more selected from water, organic solvents, oils, liquid resins, and liquid plasticizers may be used.

[0224] As organic solvents, various solvents such as alcohols, ketones, esters, hydrocarbons, and glycols can be selected. Specifically, one or more solvents can be selected from the following: alcohol solvents such as isopropanol, methanol, ethanol, 1-propanol, butanol, pentanol, benzyl alcohol, diacetone alcohol, and 1-methoxy-2-propanol; ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ester solvents such as 3-methyl-methoxy-propionate 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-pyrrolidone; aromatic hydrocarbons such as toluene and xylene; and halogenated hydrocarbons such as dichloroethane and chlorobenzene. However, organic solvents with low polarity are preferred, especially isopropanol, ethanol, 1-methoxy-2-propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, and n-butyl acetate. These organic solvents can be used alone or in combination of two or more.

[0225] As an oil, for example, one or more of the following can be used: drying oils such as flaxseed 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 that allow the fatty acids of vegetable oils to undergo direct esterification with monohydric alcohols; ethers; and petroleum-based solvents such as Isopar (registered trademark) E, Exxsol (registered trademark) Hexane, Heptane, E, D30, D40, D60, D80, D95, D110, and D130 (or more, manufactured by ExxonMobil).

[0226] As a liquid resin, one or more selected from liquid acrylic resin, liquid epoxy resin, liquid polyester resin, liquid polyurethane resin, etc. can be used.

[0227] As a liquid plasticizer, for example, liquid plasticizers for plastics can be used.

[0228] The components of an infrared absorbing particle dispersion are not limited to the infrared absorbing particles and liquid medium mentioned above. Any other components may be added to the infrared absorbing particle dispersion as needed.

[0229] For example, acid or alkali can be added to the infrared absorbing particle dispersion as needed to adjust the pH of the dispersion.

[0230] In addition, in order to further improve the dispersion stability of infrared absorbing particles and avoid coarsening of dispersed particle size due to re-aggregation in the above-mentioned infrared absorbing particle dispersion, various surfactants, coupling agents and other dispersants can be added to the infrared absorbing particle dispersion.

[0231] The surfactant, coupling agent, and other dispersants can be selected according to the application, but preferably, the dispersant has one or more functional groups selected from amino, hydroxyl, carboxyl, and epoxy groups. These functional groups adsorb onto the surface of infrared absorbing particles to prevent aggregation, and also have the effect of uniformly dispersing infrared absorbing particles in infrared shielding films formed using infrared absorbing particles. More preferably, the dispersant is a polymeric dispersant having one or more of the aforementioned functional groups (functional group groups) in its molecule.

[0232] Commercially available dispersants suitable for use include SOLSPERSE (registered trademark) 9000, 12000, 17000, 20000, 21000, 24000, 26000, 27000, 28000, 32000, 35100, 54000, 250 (manufactured by Lubrizol Co., Ltd., Japan), 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 (EFKA). Additives (company name), Ajisper (registered trademark) PA111, PB821, PB822, PN411, Famex L-12 (Made by Ajinomoto Fine Technology 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 (BYK-Chemie) One or more of the following: Disparlon (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 Chemical Co., Ltd.), and ARUFON (registered trademark) UC-3000, UF-5022, UG-4010, UG-4035, UG-4070 (manufactured by Toa Synthetic Co., Ltd.).

[0233] The method for dispersing infrared absorbing particles into a liquid medium is not particularly limited, as long as it can disperse the infrared absorbing particles into the liquid medium. In this case, it is preferable that the average particle size of the dispersed infrared absorbing particles is 800 nm or less, and more preferably that it is 1 nm or more but less than 800 nm.

[0234] Examples of methods for dispersing infrared-absorbing particles into a liquid medium include those using bead mills, ball mills, sand mills, paint shakers, and ultrasonic homogenizers. From the viewpoint of shortening the time required to achieve the desired average particle size, media-stirred mills such as bead mills, ball mills, sand mills, and paint shakers are preferred for pulverization and dispersion. By using media-stirred mills for pulverization and dispersion, while the infrared-absorbing particles are dispersed into the liquid medium, microparticles are also formed due to collisions between the infrared-absorbing particles or collisions between the medium and the infrared-absorbing particles, resulting in more microparticle-sized dispersion of the infrared-absorbing particles. In other words, a pulverization-dispersion process is performed.

[0235] 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 if the average particle size is small, light scattering can be suppressed, thereby suppressing unintentional gloss in the visible light region and unintentional hue caused by wavelength-dependent light scattering (Rayleigh scattering).

[0236] Furthermore, if coarse particles are present during the process of incorporating the composite tungsten oxide particles of this embodiment into the fiber, there is a risk of yarn breakage during spinning. From this perspective, it is also preferable to reduce the particle size of the composite tungsten oxide particles.

[0237] 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 for example, it is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more.

[0238] Based on the above reasons, the average particle size of the infrared absorbing particles is preferably 1 nm to 800 nm, more preferably 5 nm to 200 nm, even more preferably 10 nm to 200 nm, even more preferably 10 nm to 100 nm, and particularly preferably 10 nm to 30 nm.

[0239] The dispersion state of infrared absorbing particles in infrared absorbing fibers obtained using the infrared absorbing particle dispersion of this embodiment will not be more aggregated than the average particle size of infrared absorbing particles in the dispersion, provided that a known method of adding the fibers is used.

[0240] The content of infrared absorbing particles in the infrared absorbing particle dispersion 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 by making the content of infrared absorbing particles 0.01% by mass or more, sufficient solar transmittance can be achieved, that is, solar transmittance can be sufficiently suppressed. In addition, by making it 80% by mass or less, the infrared absorbing particles can be uniformly dispersed in the dispersion medium.

[0241] The infrared absorbing particle dispersion according to this embodiment, containing the aforementioned composite tungsten oxide particles, can be formulated as an infrared absorbing particle dispersion with excellent visible light transmittance and infrared shielding performance. Furthermore, the infrared absorbing particle dispersion according to this embodiment achieves excellent infrared shielding effect even with a transmittance peak of 75% or more in the wavelength range of 500 nm to 600 nm.

[0242] [Infrared Absorbing Fiber] This invention relates to infrared absorbing fibers.

[0243] Figure 4 This diagram shows a schematic representation of the infrared absorbing fiber according to this embodiment. Figure 4 A schematic cross-sectional view of the plane of the central axis CA of the fiber 41 of the infrared-absorbing fiber 40 is shown. Figure 4 As shown, the infrared absorbing fiber 40 of this embodiment may include fiber 41 and composite tungsten oxide particles 42.

[0244] The arrangement of the composite tungsten oxide particles 42 is not particularly limited; for example, the composite tungsten oxide particles 42 can be arranged at one or more positions selected from the surface 41A and interior 41B of the fiber 41. Furthermore, Figure 4 This is a schematic diagram. Although it shows an example of composite tungsten oxide particles 42 disposed on both the surface 41A and the interior 41B of the fiber 41, it is not limited to this configuration. The composite tungsten oxide particles 42 may be disposed on either the surface 41A or the interior 41B of the fiber 41. Furthermore, in Figure 4 The composite tungsten oxide particles 42 are described as spherical particles, but the shape of the composite tungsten oxide particles 42 is not limited to this form and can have any shape.

[0245] The following describes the components contained in the infrared absorbing fiber of this embodiment.

[0246] (1) Components contained in infrared absorbing fibers (1-1) Fiber (1-1-1) About the types of fibers The infrared absorbing fiber in this embodiment can be selected from various materials depending on the application, and there is no particular limitation. For example, one or more fibers selected from a group of fibers composed of synthetic fibers, semi-synthetic fibers, natural fibers, regenerated fibers, and inorganic fibers, as well as blended yarns made from two or more fibers selected from the aforementioned fiber groups through blending, plying, or mixing, can be used. That is, fibers selected from the aforementioned fiber groups or fibers selected from the aforementioned blended yarns can be used.

[0247] In particular, considering the ease with which infrared absorbing particles are contained within the fiber, and the durability of heat retention, the fiber preferably contains synthetic fibers, and more preferably is composed of synthetic fibers.

[0248] The following describes each fiber.

[0249] (synthetic fiber) As a synthetic fiber, there are no particular limitations. For example, one or more of the following can be used: polyurethane fiber, polyamide fiber, acrylic fiber, polyester fiber, polyolefin fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyvinyl chloride fiber, polyether ester fiber, etc.

[0250] Examples of polyamide fibers include nylon, nylon 6, nylon 66, nylon 11, nylon 610, nylon 612, aromatic nylon, and aramid.

[0251] Examples of acrylic fibers include polyacrylonitrile, acrylonitrile-vinyl chloride copolymer, and modified polyacrylonitrile fiber MODACRYLIC.

[0252] Examples of polyester fibers include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, and polyethylene naphthalate.

[0253] Examples of polyolefin fibers include polyethylene, polypropylene, and polystyrene.

[0254] Examples of polyvinyl alcohol-based fibers include vinylon.

[0255] Examples of polyvinylidene chloride-based fibers include, for example, vinylidene chloride.

[0256] Examples of polyvinyl chloride (PVC) fibers include, for example, polyvinyl chloride.

[0257] Examples of polyether ester fibers include Rexe and Success.

[0258] (Semi-synthetic fiber) As a semi-synthetic fiber, one or more of the following can be used: cellulose-based fibers, protein-based fibers, chlorinated rubber, hydrochloric acid rubber, etc.

[0259] Examples of cellulose-based fibers include cellulose acetate, cellulose triacetate, and cellulose oxidized acetate.

[0260] As a protein-based fiber, Promix is ​​an example.

[0261] (Natural fiber) As a natural fiber, it can be selected from one or more types of plant fibers, animal fibers, mineral fibers, etc.

[0262] Examples of plant fibers include cotton, kapok, flax, hemp, jute, Manila hemp, sisal, New Zealand hemp, Apocynum venetum, coconut, rush, and wheat straw.

[0263] Animal fibers include, for example, wool, goat hair, mohair, cashmere, alpaca wool, angora wool, camel hair, pygmy alpaca wool, silk, down, feathers, etc.

[0264] Examples of mineral fibers include asbestos and other mineral fibers.

[0265] (Regenerated Fiber) As a regenerated fiber, one or more of the following can be used: cellulose fiber, protein fiber, alginate fiber, rubber fiber, chitin fiber, mannan fiber, etc.

[0266] Examples of cellulose-based fibers include rayon, viscose rayon, cupro rayon, high wet modulus rayon, and cupro rayon.

[0267] Examples of protein-based fibers include casein fiber, peanut protein fiber, corn protein fiber, soybean protein fiber, and regenerated silk.

[0268] (Inorganic fibers) As an inorganic fiber, one or more types selected from metal fibers, carbon fibers, silicate fibers, etc. can be used.

[0269] Examples of metal fibers include metal fibers, gold wires, silver wires, and heat-resistant alloy fibers.

[0270] Examples of silicate fibers include glass fiber, slag fiber, and rock fiber.

[0271] (1-1-2) Fiber shape The cross-sectional shape of the fiber is not particularly limited; for example, one or more can be selected from circular, triangular, hollow, flat, Y-shaped, star-shaped, core-sheath type, etc.

[0272] There are no particular limitations on the morphology of the composite tungsten oxide particles contained in the fiber. For example, when the fiber cross-sectional shape is core-sheath type, the composite tungsten oxide particles can be contained in the fiber core or in the sheath. In addition, there are no particular limitations on the shape of the fiber; it can be a filament (long fiber) or a short fiber (short fiber).

[0273] (1-2) Composite tungsten oxide particles The description of composite tungsten oxide particles has already been provided, so it will be omitted here.

[0274] In the infrared absorbing fiber of this embodiment, the content of composite tungsten oxide particles is not particularly limited and can be selected according to the required characteristics of the infrared absorbing fiber. The infrared absorption capacity per unit weight of composite tungsten oxide particles is very high, so its effect can be achieved with an amount of about 1 / 4 to 1 / 10 compared to ITO or ATO.

[0275] The infrared absorbing fiber of this embodiment may contain composite tungsten oxide particles in a proportion of 0.001% to 80% by mass relative to the solid composition of the fiber. Furthermore, considering the fiber weight and raw material cost after adding composite tungsten oxide particles, the infrared absorbing fiber of this embodiment more preferably contains composite tungsten oxide particles in a proportion of, for example, 0.005% to 50% by mass.

[0276] By including composite tungsten oxide particles in the infrared-absorbing fiber at a proportion of 0.001% by mass or more relative to the fiber solids content, sufficient infrared absorption can be achieved even in thinner fabrics containing these particles. Furthermore, by including composite tungsten oxide particles at a proportion of 80% by mass or less relative to the fiber solids content, reduced spinnability due to filter clogging or thread breakage can be more effectively avoided during the spinning of the infrared-absorbing fiber. Additionally, by keeping the aforementioned content of composite tungsten oxide particles at 80% by mass or less, damage to the physical properties of the fiber can be more effectively avoided.

[0277] (1-3) Additives, far-infrared radiating substances The infrared absorbing fiber of this embodiment may consist only of the above-described fiber and composite tungsten oxide particles, but may also contain any other components, such as far-infrared radiating substances or additives as described below, depending on the purpose.

[0278] (additive) The infrared absorbing fiber involved in this embodiment may also contain antioxidants, flame retardants, deodorants, insect repellents, antibacterial agents, ultraviolet absorbers, etc., depending on the purpose, without impairing the fiber's performance.

[0279] (Far-infrared radiating substances) Far-infrared radiating materials are materials capable of radiating far-infrared rays, preferably in particle form. That is, far-infrared radiating material particles are preferred as far-infrared radiating materials.

[0280] Far-infrared radiating materials can be placed at one or more locations selected from the fiber surface and interior.

[0281] Examples of far-infrared radiating substances include one or more metal oxides such as ZrO2, SiO2, TiO2, Al2O3, MnO2, MgO, Fe2O3, and CuO; carbides such as ZrC, SiC, and TiC; and nitrides such as ZrN, Si3N4, and AlN.

[0282] Examples of composite tungsten oxide particles include those containing cesium tungsten oxide. Cesium tungsten oxide has the property of absorbing solar energy in the wavelength range of 300 nm to 3000 nm, and in particular, selectively absorbing infrared radiation in the region of 900 nm to 2500 nm, converting it into heat or re-radiation.

[0283] On the other hand, the particles of the far-infrared radiating material have the ability to receive the energy absorbed by cesium tungsten oxide, which is an infrared absorbing material, and convert this energy into heat energy with mid- to far-infrared wavelengths, which is then radiated. For example, ZrO2 particles convert this energy into heat energy with wavelengths between 2000 nm and 20000 nm and radiate it. Therefore, by having this far-infrared radiating material with far-infrared radiating ability coexist with composite tungsten oxide particles inside or on the surface of the fiber, the solar energy absorbed by the composite tungsten oxide particles is efficiently consumed inside or on the surface of the fiber, thus achieving more effective heat preservation.

[0284] There is no particular limit to the content of far-infrared radiating substances in infrared absorbing fibers; the content can be selected based on the required performance of the infrared absorbing fibers.

[0285] The infrared absorbing fiber of this embodiment preferably contains far-infrared radiating substances in a proportion of, for example, 0.001% by mass or more and 80% by mass or less relative to the solid composition of the fiber.

[0286] This is because by ensuring that the far-infrared radiating material contains 0.001% by mass or more, even a thin fabric containing infrared absorbing fibers can achieve sufficient heat radiation. Furthermore, by ensuring that the far-infrared radiating material contains 80% by mass or less, the reduced spinnability of the infrared absorbing fibers can be more reliably prevented during spinning due to filter clogging or thread breakage.

[0287] (2) Manufacturing method of infrared absorbing fiber This embodiment describes a method for manufacturing infrared absorbing fibers. Since the infrared absorbing fibers described previously can be manufactured using this method, previously stated details are omitted.

[0288] The method for manufacturing infrared absorbing fibers in this embodiment may include an infrared absorbing fiber manufacturing process for modulating infrared absorbing fibers containing fibers and composite tungsten oxide particles.

[0289] The composite tungsten oxide particles and fibers have already been explained, so the explanation is omitted here.

[0290] In the manufacturing process of infrared absorbing fibers, specifically, for example, composite tungsten oxide particles can be disposed at one or more locations selected from the fiber surface and interior.

[0291] There are no particular limitations on the method of depositing composite tungsten oxide particles at one or more locations selected from the fiber surface and interior. For example, any of the methods (a) to (d) below can be used.

[0292] (a) A method for spinning by directly mixing composite tungsten oxide particles into a raw material polymer of synthetic fibers.

[0293] (b) A method of pre-manufacturing a masterbatch containing a high concentration of composite tungsten oxide particles in a portion of the raw material polymer, and then diluting the masterbatch to a specified concentration during spinning before spinning.

[0294] (c) A method of pre-preparing a dispersion solution in which composite tungsten oxide particles are dispersed in a solution of raw material monomers or oligomers. Then, using this dispersion solution to synthesize the target raw material polymer while simultaneously dispersing the composite tungsten oxide particles in the raw material polymer, followed by spinning.

[0295] (d) A method of attaching composite tungsten oxide particles to the surface of pre-spun fibers using an adhesive or the like.

[0296] Here, specific examples are given to further illustrate the methods (a) to (d) above.

[0297] (a) Method: Let's take the case of using polyester fiber as the fiber as an example.

[0298] First, a dispersion of composite tungsten oxide particles is added to polyethylene terephthalate resin particles, which are thermoplastic resins. After uniform mixing in a mixer, the solvent is removed. The mixture, from which the solvent has been removed, is then melt-blended using a twin-screw extruder to obtain a masterbatch containing composite tungsten oxide particles. The obtained masterbatch is then melt-blended near the melting temperature of the resin, and spun, for example, by various known methods, to produce infrared-absorbing fibers.

[0299] Furthermore, the manufacturing method of the aforementioned masterbatch is not particularly limited. For example, a masterbatch in which composite tungsten oxide particles are dispersed in a thermoplastic resin can be prepared by first using a mixer to remove solvent while melting and mixing a dispersion of composite tungsten oxide particles, powder or granules of thermoplastic resin, and other additives as needed.

[0300] There are no particular limitations on the type of mixing machine. For example, one or more of the following can be used: belt mixer, drum mixer, Nota mixer, Henschel mixer, super mixer, planetary mixer, Banbury internal mixer, kneader, roller, kneading extruder, single screw extruder, twin screw extruder, etc.

[0301] The preparation method of the mixture in which composite tungsten oxide particles are dispersed in the resin is not limited to the above-described form.

[0302] For example, after preparing a dispersion of composite tungsten oxide particles, the dispersion medium is first removed using a known method. Then, by uniformly melting and mixing the powder obtained after removing the dispersion medium, the powder or granules of the thermoplastic resin, and other additives as needed, a mixture in which composite tungsten oxide particles are dispersed in a thermoplastic resin can also be produced. Alternatively, in the production of a mixture in which composite tungsten oxide particles are dispersed in a thermoplastic resin, a method can be used where the composite tungsten oxide particles are directly added to the thermoplastic resin and melt-mixed.

[0303] The mixture of composite tungsten oxide particles obtained by the above method and thermoplastic resin is kneaded using a vented single-screw or twin-screw extruder and processed into granules, thereby obtaining a masterbatch containing infrared absorbing particles.

[0304] The masterbatch is melt-mixed with a target amount of polyethylene terephthalate masterbatch without the addition of composite tungsten oxide particles at a temperature near the melting temperature of the resin, and then spun according to a known method.

[0305] Method (b): Using the same method as (a), a masterbatch containing composite tungsten oxide particles is prepared. Then, this masterbatch is melt-mixed with a masterbatch composed of polyethylene terephthalate without the addition of composite tungsten oxide particles at a desired mixing ratio near the melting temperature of the resin and spun according to a known method, thereby producing infrared absorbing fibers.

[0306] Method (c): For example, let's take the case where polyurethane fiber is used as the fiber as an example.

[0307] 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. This prepolymer is then reacted with a chain extender to produce a polyurethane solution (raw material polymer). Infrared absorbing particles can be manufactured by spinning this polyurethane solution using various known methods.

[0308] (d) Method: For example, the case of attaching composite tungsten oxide particles to the surface of natural fibers will be used as an example.

[0309] First, a treatment solution is prepared by mixing composite tungsten oxide particles, an adhesive resin selected from acrylic, epoxy, polyurethane, polyester, and a solvent such as water.

[0310] Next, the natural fiber is immersed in a prepared treatment solution, or the prepared treatment solution is applied to the natural fiber through padding, printing, or spraying, and then dried. This allows the composite tungsten oxide particles to adhere to the natural fiber. Furthermore, method (d) can be applied not only to natural fibers, but also to synthetic fibers, semi-synthetic fibers, regenerated fibers, inorganic fibers, or any blends, twists, or polymers thereof.

[0311] Furthermore, there are no particular limitations on the method of preparing the composite tungsten oxide particle dispersion that can be used when implementing the methods described in (a) to (d) above. For example, it can be prepared by the method described above in the process of infrared absorption of particle dispersion.

[0312] In addition, the dispersion medium of the composite tungsten oxide particle dispersion is not particularly limited and can be selected in conjunction with the mixed fibers. For example, various common organic solvents such as alcohols, ethers, esters, ketones, and aromatic compounds, or water can be preferred.

[0313] When attaching or mixing composite tungsten oxide particles into fibers or their raw material polymers, the dispersion of composite tungsten oxide particles can also be directly mixed into the fibers or their raw material polymers. Additionally, acid or alkali can be added to the composite tungsten oxide particle dispersion to adjust the pH as needed. To further improve the dispersion stability of the composite tungsten oxide particles, various surfactants, coupling agents, etc., can also be added.

[0314] As explained above, the infrared-absorbing fiber of this embodiment contains composite tungsten oxide particles as an infrared-absorbing component. Even with a low content of composite tungsten oxide particles, the infrared-absorbing fiber of this embodiment can efficiently absorb near-infrared rays from sunlight and other sources, converting them into heat. Therefore, even with a low content of composite tungsten oxide particles, it can provide a fiber with excellent heat retention. Furthermore, because the infrared-absorbing fiber of this embodiment can reduce the content of composite tungsten oxide particles, it does not compromise the design of fiber products and avoids compromising the basic physical properties of the fiber, such as strength and elongation. As a result, the fiber of this embodiment can be used for various applications, including cold-weather clothing, sportswear, stockings, curtains, and other industrial fiber products requiring heat retention. Moreover, when the infrared-shielding fiber structure of this embodiment is used in clothing, the amount of infrared rays contained in natural light reaching the human skin can be reduced, thus minimizing skin damage. If the fiber product of this embodiment is used as a curtain and placed on the windows of buildings, the curtain absorbs the infrared rays contained in sunlight and becomes a curtain with infrared shading function, thereby blocking the infrared rays of sunlight entering the window, and thus suppressing the rise of room temperature in summer.

[0315] Furthermore, the infrared-absorbing fiber according to this embodiment possesses excellent infrared absorption performance even with a low content of composite tungsten oxide particles, which are infrared-absorbing particles. Therefore, it can prevent the transmission or reflection of infrared light, thus preventing both so-called "spy camera" photography and damage to the fiber's tactile feel. Consequently, it can be used as an infrared-absorbing fiber for so-called anti-spy camera purposes for various applications.

[0316] [Fiber Products] The fiber product of this embodiment is made by processing the aforementioned infrared absorbing fibers, and may include the aforementioned infrared absorbing fibers. Alternatively, the fiber product of this embodiment may also be composed of the aforementioned infrared absorbing fibers.

[0317] (1) The anti-spy camera function of the fiber product in this embodiment for CCD cameras Fabrics using the infrared-absorbing fibers of this embodiment and fiber products using the fabric as clothing, wherein the content of composite tungsten oxide particles, such as cesium tungsten composite oxide, per unit area is 0.08 g / m² 2 The above methods can be used to prevent infrared covert photography (CCD camera see-through) as tested by the Japan Textile Association (Boken standard "BQE A 033").

[0318] From the viewpoint of providing a function to prevent CCD camera covert photography, the fiber product (infrared shielding fiber structure) using the infrared absorbing fiber of this embodiment has a composite tungsten oxide particle content of 0.08 g / m² per unit area, as described above. 2 The preferred value is 0.15 g / m³. 2 The above, more preferably 0.20 g / m 2 That's all. The upper limit of the unit area content of the composite tungsten oxide particles in the fiber product of this embodiment is not particularly limited; for example, it can be 4.5 g / m². 2 the following.

[0319] Therefore, the unit area content of the composite tungsten oxide particles in the fiber product of this embodiment can be 0.08 g / m². 2 The above 4.5g / m 2 The preferred value is 0.15 g / m³. 2 The above 4.5g / m 2 The following is more preferably 0.20 g / m 2 The above 4.5g / m 2 the following.

[0320] If the content of composite tungsten oxide particles per unit area of ​​the fiber product in this embodiment is 0.08 g / m² 2 Therefore, the average reflectance of the fiber product in the infrared region (wavelength 800nm ​​to 1300nm) can be set to 65% or less. If the average reflectance of the fiber product in this embodiment is 65% or less, infrared covert photography (CCD camera see-through) can be prevented in clothing made from fabrics or knitted garments using the fiber product of this embodiment. More preferably, the average reflectance of the fiber product in this embodiment is 60% or less, and even more preferably 55% or less.

[0321] The average reflectivity of the fiber product in this embodiment can be selected by the content of composite tungsten oxide particles per unit area. For example, the content of composite tungsten oxide particles per unit area of ​​the fiber product in this embodiment can be set to 0.15 g / m². 2 The above allows the average reflectivity of the fiber product to be below 60%. Furthermore, by setting the content of composite tungsten oxide particles per unit area of ​​the fiber product in this embodiment to 0.20 g / m², [further improvements can be achieved]. 2 The above measures can reduce the average reflectivity of fiber products to below 55%.

[0322] When the content of composite tungsten oxide particles per unit area of ​​the fiber product of this embodiment exceeds 4.5 g / m² 2At this point, the average reflectivity will be less than 0.07%, but even if the average reflectivity is further reduced, the effect of preventing infrared eavesdropping will not be further improved. Therefore, the content of composite tungsten oxide particles per unit area of ​​the fiber product in this embodiment can be 4.5 g / m² as described above. 2 The following can also be 3.5g / m 2 The following applies if the content of composite tungsten oxide particles per unit area is 3.5 g / m². 2 Below this level, the average reflectance is below 0.2%, effectively preventing infrared surreptitious photography. However, if the fiber product contains an excessive amount of composite tungsten oxide particles per unit area, it may sometimes cause difficulties in color development, depending on the color of the fiber product's dyeing process.

[0323] Furthermore, fiber products without composite tungsten oxide particles have an average reflectance of 77% in the infrared region (wavelength 800nm~1300nm), as confirmed in the following reference example. This average reflectance makes infrared covert photography (CCD camera see-through) possible.

[0324] In addition, the above-mentioned average reflectance refers to the average reflectance of fiber products measured by a spectrophotometer at 5 nm intervals in the region with wavelengths above 800 nm and below 1300 nm.

[0325] Regarding solutions to prevent infrared spying (CCD camera see-through), it is important to consider the reflectivity of fiber products.

[0326] When we look at an object, we can recognize it because the light shining on the object reflects off it and forms an image of the object in our eyes. The same is true for images captured by cameras.

[0327] Furthermore, in the fiber product, composite tungsten oxide particles that absorb infrared radiation are present at one or more locations selected from the fiber surface and interior. If the fiber product is irradiated with light, these composite tungsten oxide particles absorb infrared radiation, thus reducing the reflectivity of the infrared region with wavelengths exceeding 780 nm. In other words, the reflectivity of infrared radiation decreases in the light component irradiating the fiber product of this embodiment. As a result, even when attempting to photograph the fiber product of this embodiment with a CCD camera, the image becomes unclear due to the reduced reflectivity in the region with wavelengths exceeding 780 nm.

[0328] Furthermore, the wavelength range of widely used CCD cameras is known to be 400nm to 1200nm. In the fiber product of this embodiment, since the reflectivity of the infrared region with wavelengths exceeding 780nm in the illuminated light component decreases, infrared covert photography (CCD camera see-through) can be prevented. Thus, although a camera device for infrared covert photography has been described using a CCD camera as an example, the fiber product of this embodiment can prevent covert photography using infrared-capable camera devices regardless of the type of camera.

[0329] On the other hand, the light absorption of the composite tungsten oxide particles contained in the fiber product of this embodiment in the visible light region is very small compared to the light absorption in the infrared region where the wavelength exceeds 780 nm. That is, since the composite tungsten oxide particles contained in the fiber product of this embodiment have low light absorption in the visible light region, the fiber product can be freely colored by dyeing or the like.

[0330] Example The following specific embodiments are provided for illustration, but the present invention is not limited to these embodiments.

[0331] (1) Evaluation method (1-1) Powder X-ray diffraction pattern For the composite tungsten oxide particles, powder X-ray diffraction (XRD) patterns were determined using a BRUKER D2 PHASER apparatus. Additionally, CuKα rays were used as the radiation source, with a tube voltage of 45 kV and a tube current of 40 mA, and powder X-ray diffraction patterns were also determined.

[0332] (1-2) STEM and HAADF image observation The obtained composite tungsten oxide particles were observed using a transmission electron microscope. High-angle annular dark-field (HAADF) images were also observed using a JEOL STEM (model: JEM-ARM200F). The atomic number (Z) contrast in the HAADF image is proportional to the square of the atomic number of the atoms in the particle and the number of atoms. Since the more layers of heavy atoms are stacked, the brighter the contrast, the brightest and second brightest contrast is considered to be W, the third brightest contrast is Cs, and O cannot be confirmed.

[0333] The sample was placed on a Cu grid with a support film using a dispersion method for observation.

[0334] During observation, a high-angle scattering dark-field image (STEM-HAADF) was acquired using an accelerating voltage of 200 kV. This image was obtained by detecting only electrons with large scattering angles among those that passed through the sample, thus obtaining contrast due to compositional differences, as described above. Furthermore, since the scattering angle is proportional to the square of the atomic number (Z), elements with larger atomic numbers exhibit brighter contrast. In the case of the composite tungsten oxide particles modulated in the Examples and Comparative Examples, Cs and W can be identified by the difference in contrast.

[0335] In the evaluation, to distinguish between defective and non-defective areas of W, the difference in contrast intensity within the tungsten pillars (W pillars) in the STEM-HAADF image, which are configured as spots (dots) of tungsten, was used. If W is defective, the maximum value of Z contrast is reduced at that spot.

[0336] The contrast evaluation of the observed STEM-HAADF images was performed using DigitalMicrograph (Version 3.43.3213.0) manufactured by Gatan. The software was used to read the observation data, and the contrast of corresponding areas was extracted using the line distribution plot function.

[0337] In STEM-HAADF imaging, particles larger than 50 nm were selected from dispersed composite tungsten oxide particles to suppress electron beam-induced degradation. Furthermore, the particle size used for observation was determined by the diameter of the smallest circumscribed circle containing the particles. Then, to clearly distinguish the Z-contrast of W atoms, observations were performed with a field of view size between 20 nm square and 50 nm square.

[0338] Figure 5 Cs-WO compounds exhibiting a hexagonal crystal structure are known as hexagonal Cs. 0.33 The crystal structure of WO3 in the

[001] incident direction, i.e., on the (001) plane. Only W / W columns 501 containing W atoms 51 are arranged, and W / Cs columns 502 alternately contain W atoms 51 and Cs atoms as M element 53. Furthermore, the region S between the double arrows representing the a-axis length and b-axis length in the figure is the unit cell. W pillars and Cs pillars exist in the c-axis direction perpendicular to the paper plane, with 3 columns of W pillars and 1 column of Cs pillars in each region S.

[0339] When calculating the proportion of dark areas in the Z-contrast of tungsten atoms in a STEM-HAADF image, first refer to Figure 5 The crystal structure shown is used to count the number of W pillars within the field of view.

[0340] Next, the software described above is used to calculate the maximum Z-contrast of each W-pillar spot within the observation field of view, and its average value is obtained. Additionally, the number of dark spots (the spots whose maximum Z-contrast of each W-pillar spot within the observation field of view is less than 95% of the aforementioned average value) is counted.

[0341] Then, calculate the ratio of the number of dark areas in the field of view to the number of W pillars in the field of view.

[0342] (1-3) Transmittance distribution diagram The optical properties of the infrared-absorbing particle dispersion were determined using a spectrophotometer (Hitachi, Ltd. U-4100) at 5 nm intervals in the wavelength range of 200 nm to 2600 nm.

[0343] (1-4) Composition Analysis The proportions of each component in the composite tungsten oxide particles were evaluated using the following methods.

[0344] The mass ratio of Cs was determined three times for each sample using a polarized Zeeman atomic absorption spectroscopy (AAS, model: ZA3300, manufactured by Hitachi High Technology Co., Ltd.) and the average value was obtained.

[0345] The mass ratio of W was determined by analyzing each sample three times using inductively-coupled plasma optical emission spectroscopy (ICP-OES, model: ICPE-9800, manufactured by Shimadzu Corporation) to obtain the average value.

[0346] The mass ratio of O was determined by an oxygen-nitrogen-hydrogen analyzer (ON-836, LECO Japan Corp.) using an infrared absorption spectroscopy (IRS) detector for oxygen detection, with each sample analyzed three times and the average value taken.

[0347] [Example 1] (1) Manufacturing of composite tungsten oxide particles use Figure 1 The composite material manufacturing apparatus 10 shown Figure 2 The reduction treatment apparatus shown was used to manufacture and evaluate composite tungsten oxide particles. Specific conditions are described below.

[0348] The composite material manufacturing apparatus 10 has a storage section 11 in which a solution containing W and M element sources is placed as a raw material solution, a two-fluid nozzle 12 that forms raw material droplets and forms a flame, and a reaction tube 13 connected to a filter 14 that recovers the formed composite tungsten oxide particles.

[0349] The feed solution supply rate to the dual-fluid nozzle 12 is set to 3 g / min. Additionally, the oxygen flow rate, used as the carrier gas, is controlled by the injector 15 and set to 15 L / min. The air flow rate in the injector 15 is controlled within the range of 160 L / min to 180 L / min.

[0350] The flame formation of the dual-fluid nozzle 12 uses propane and oxygen, with the propane flow rate set to 1.2 L / min and the oxygen flow rate set to 6.0 L / min.

[0351] As raw materials, a mixed solution containing W element source W(CO)6 dissolved in THF (tetrahydrofuran) and a mixed solution containing element M cesium acetate dissolved in ethanol are used and stored in storage compartment 11. The mixed solution is prepared such that the ratio of the amount of element M Cs (Cs) to the amount of element tungsten (W), i.e., Cs / W, is 0.37.

[0352] The above-mentioned raw material solution and oxygen as carrier gas are supplied from the storage section 11 to the dual-fluid nozzle 12 to form an aerosol (aerosol formation process).

[0353] As described above, propane and oxygen are supplied to the dual-fluid nozzle 12 to form a flame reaction field. The resulting aerosol is supplied into the flame for heat treatment (heat treatment process).

[0354] In the heat treatment process, heat treatment conditions were selected such that the resulting composite tungsten oxide particles exhibited appropriate W atom defects or heterogeneous phases, and that composite tungsten oxide particles with confirmed W atom-related Z-contrast reduction spots were produced after the reduction treatment process. Specifically, the heat treatment conditions were selected based on the results of prior experimental studies. Furthermore, the heat treatment process involved heat-treating the raw materials at temperatures above 550°C.

[0355] The composite tungsten oxide particles obtained in the heat treatment process are introduced into the reaction tube 13. Cooling water piping 131 is arranged around the reaction tube 13, and the cooling water is circulated. The composite tungsten oxide particles introduced into the reaction tube 13 are recovered through a filter 14, which acts as a bag filter.

[0356] The composite tungsten oxide particles obtained after the heat treatment process were evaluated by XRD patterns.

[0357] Figure 6 The XRD pattern of the obtained composite tungsten oxide particles is shown. Figure 6 In the image, XRD pattern (A), shown as the "prepared state," is the XRD pattern of the composite tungsten oxide particles after heat treatment. It was identified as being composed of hexagonal Cs... 0.33 WO3 (ICDD: 81-1245) or orthorhombic Cs4W 11 O 35 The crystal phase consists of (ICDD: 51-1891) and a small amount of cubic pyrochlore (Cs₂O). 0.44 W2O6 (ICDD: 47-0566) phase. Identification of a small number of crystalline phases was performed using Rietveld analysis.

[0358] Furthermore, using Figure 2 The restoration processing device 20 shown performed the restoration process.

[0359] like Figure 2 As shown, under a gas flow of 3 volume% H2 / 97 volume% Ar, a heater 22 was placed around the reaction tube 21, and the temperature was raised from room temperature to 500°C. After the portion of the container 23 reached the reduction treatment temperature, it was maintained for 2 hours, and then cooled to room temperature, thereby performing the reduction treatment (reduction treatment step). Thus, reduced particles of composite tungsten oxide particles as Example 1 were obtained.

[0360] Figure 6 The XRD pattern of the obtained composite tungsten oxide particles is shown. Figure 6 In the image, the XRD pattern (B) shown as "heat treatment" is the XRD pattern of the composite tungsten oxide particles after the reduction treatment process. It is confirmed that the obtained XRD pattern contains only Cs. 0.33 The diffraction peaks of WO3 indicate that its crystal system is hexagonal.

[0361] The composite tungsten oxide particles following the reduction treatment process in Example 1 were subjected to the previously described compositional analysis, and the Cs / W ratio, which is the molar ratio of cesium to tungsten, was determined. The results confirmed that the Cs / W ratio decreased from 0.37 in the initial composition to 0.34. However, this value of 0.34 is 0.01 higher than the theoretical composition of 0.33, and the XRD pattern showed a single phase; therefore, it is considered that there is almost no Cs deficiency.

[0362] Furthermore, compositional analysis of the composite tungsten oxide particles confirmed an O / W ratio of 2.841, representing the molar ratio of oxygen to tungsten. In the following description, the composite tungsten oxide particles, along with their XRD pattern evaluation, are described as Cs. 0.33 WO3.

[0363] (2) Preparation of infrared absorbing particle dispersion Weigh 10% by mass of the composite tungsten oxide particles after the reduction treatment process of Example 1, 10% by mass of an acrylic polymeric dispersant (acrylic dispersant with an amine value of 48 mg KOH / g and a decomposition temperature of 250°C), and 80% by mass of toluene. Place the weighed materials together with 0.05 mm diameter zirconia beads into a coating shaker and disperse them for 100 minutes to obtain Cs as the infrared absorbing particle dispersion of Example 1. 0.33 WO3 particle dispersion.

[0364] The average particle size (measured by transmission electron microscopy) of the composite tungsten oxide particles in the dispersion of Example 1 was 27.2 nm.

[0365] Furthermore, the average particle size of the composite tungsten oxide particles was observed and calculated using transmission electron microscopy in three fields of view. Specifically, images of a total of 600 to 700 composite tungsten oxide particles were observed in the three fields of view. The area of ​​each particle was calculated from the binarized data, and the diameter of each particle converted to a circle was calculated. Then, the arithmetic mean of the particle sizes of all evaluated composite tungsten oxide particles, i.e., the diameters converted to circles, was taken as the average particle size.

[0366] Take Cs related to Example 1 0.33 The WO3 particle dispersion was desolventized to obtain Cs, which is the composite tungsten oxide particle involved in Example 1. 0.33 WO3 particles.

[0367] Figure 7A , Figure 7B The image shows the composite tungsten oxide particles, namely Cs, involved in Example 1. 0.33 STEM-HAADF image of WO3 particles. Figure 7A Displays a STEM-HAADF image of the entire particle. Additionally, Figure 7B Show magnified view Figure 7A An image of quadrilateral region 71 in the particle shown. Figure 7B As shown, the size of the observation field was adjusted to approximately 20 nm square. Within this particle, approximately 15 regions with low Z-contrast of W atoms were identified, i.e., dark areas. Regarding the number of tungsten pillars in this field of view, since there are 3 tungsten pillars in the unit cell, based on the unit cell size and the field size, 2249 pillars were calculated in the field. That is to say, W defects exist in 0.67% of the pillars.

[0368] The dark areas, which are regions with low contrast, are spots where the maximum Z-contrast of the tungsten column spots drops to below 95% of the average.

[0369] Figures 8A to 8F The STEM-HAADF image of the composite tungsten oxide particles in Example 1 shows the line distribution of W defects. Figures 8A to 8F Corresponding to Figure 7B Line distribution diagram of lines L1 to L6 in the diagram.

[0370] Even within the same straight line, Z-contrast can vary depending on factors such as particle thickness or tilt relative to the electron beam. However, by averaging the maximum Z-contrast value of each tungsten column spot within the field of view, the Z-contrast intensity of W atoms in the block region without W defects is taken as the basis. Using the average of the maximum Z-contrast values ​​of each tungsten column spot within the field of view as a benchmark, the regions where the maximum contrast value of the tungsten column spots is below 95% relative to the average value are considered as W defect regions.

[0371] exist Figure 8AIn line L1 shown, the maximum Z contrast at point P1 drops to 89.1% relative to the average, and at point P2 it drops to 88.4%. These points are the W defects.

[0372] exist Figure 8B In line L2 shown, at points P3 to P6, the maximum Z contrast decreases to 89.3%, 92.8%, 93.2%, and 91.35% respectively relative to the average value.

[0373] exist Figure 8C In line L3 shown, at points P7 and P8, the maximum Z contrast decreases to 86.95% and 85.6% respectively relative to the average value.

[0374] exist Figure 8D In line L4 shown, at points P9 and P10, the maximum Z contrast decreases to 89.2% and 89.4% respectively relative to the average value.

[0375] exist Figure 8E In line L5 shown, at point P11, the maximum Z contrast decreases to 88.6% relative to the average.

[0376] exist Figure 8F In line L6 shown, at points P12 to P15, the maximum Z contrast values ​​decrease to 94.0%, 93.2%, 93.4%, and 90.6% respectively relative to the average value.

[0377] Figure 12A This refers to a STEM-HAADF image, specifically an image of the prismatic facet, incident from

[110] on the composite tungsten oxide particles involved in Example 1. Figure 12A The defect surface 121 is caused by W atom defects perpendicular to the c-axis. This defect is a defect on the base surface (001). Figure 12B yes Figure 12A A magnified view of the defect surface. It was confirmed that there is a space 122 adjacent to the defect where Cs and W atoms are absent, with a length of approximately 3 nm along the c-axis. These defect surfaces 121, which serve as basal surface defects, and the spaces 122 where Cs and W are absent along the c-axis, are believed to be remnants left as interfaces of crystallization regions during the rearrangement of Cs and W atoms within the crystal during the heat treatment process.

[0378] Furthermore, a distorted structure with a 1 / 4 period shift in the crystal structure was confirmed to exist, with a defect surface 121 sandwiched between W atoms with a length of approximately 30 nm perpendicular to the c-axis. Figure 13 It is a schematic representation Figure 12A , Figure 12B A diagram showing the configuration of W and Cs atoms.

[0379] As for the optical properties of the infrared absorbing particle dispersion relating to Example 1, the transmittance pattern was measured under the conditions described above. The results of the transmittance pattern show... Figure 11A The transmittance for each wavelength is shown in Table 1.

[0380] In addition, when measuring optical properties, the infrared absorbing particle dispersion was adjusted to have a visible light transmittance of 80%.

[0381] The molar absorptivity curve was determined from the absorbance curve obtained by measuring the transmittance distribution of the infrared absorbing particle dispersion involved in Example 1. Then, the molar absorptivity curve was separated into three absorption elements: the absorption curve of localized surface plasmon resonance (LSPR⊥) perpendicular to the c-axis, the absorption curve of localized surface plasmon resonance (LSPR / / ) parallel to the c-axis, and the absorption curve of polaron absorption. The results are as follows... Figure 15A As shown. Figure 15A In this text, “exp.” represents the measured value, and “calc” represents the sum of the absorption curves of the three absorption elements.

[0382] Table 2 shows the peak positions, peak intensities, and integrated intensities of the absorption curves involving the three absorption elements. Furthermore, Table 3 shows the ratio of the integrated intensities of the absorption curves for the three absorption elements to the integrated intensities of the molar absorptivity curve.

[0383] Furthermore, the values ​​of L*, a*, and b*, representing colorimetry, were calculated from the spectrophotometer measurement data. The results are shown in Table 4.

[0384] (3) Manufacturing of infrared absorbing fibers Regarding the infrared absorbing particle dispersion involved in Example 1, toluene was removed using a spray dryer to obtain Cs. 0.33 WO3 dispersible powder (Powder A).

[0385] The obtained dispersion powder (powder A) was added to polyethylene terephthalate resin particles, which are thermoplastic resins. After uniform mixing in a mixer, the mixture was melt-kneaded and extruded using a twin-screw extruder. The extruded wire was then cut into granules. Through the above operations, Cs containing heat radiation absorbing components was obtained. 0.33 WO3 particles 40% by mass masterbatch (masterbatch a1).

[0386] Melt spinning masterbatch a1 is then stretched to produce polyester multifilament yarn a1. The resulting polyester multifilament yarn a1 is then cut to produce polyester staple fiber a1.

[0387] In addition, melt spinning does not contain Cs. 0.33The WO3 particles are then stretched to produce polyester multifilament yarn a2. The resulting polyester multifilament yarn a2 is cut to produce polyester staple fiber a2. The polyester staple fiber a1 is used to produce spinning yarn a1, and the polyester staple fiber a2 is used to produce spinning yarn a2.

[0388] (4) Manufacturing of thermal insulation knitted fabrics as fiber products The fiber product, namely knitted product a1, which has near-infrared absorption properties, is obtained by using yarn a1 and yarn a2. Knitted product a1 is manufactured by adjusting the mixing ratio of yarn a1 and yarn a2 to achieve a solar reflectance of 8%.

[0389] (Evaluation of the effect of temperature increase) Next, the temperature rise effect on the back of the fabric of the knitted product a1 was measured as follows.

[0390] In an environment of 20°C and 60%RH, a solar-spectrum lamp (Seric Co., Ltd. solar simulator XL-03E50 modified) was used to irradiate the knitted fabric from a distance of 30cm. The temperature of the back 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 (Minolta Co., Ltd. HT-11).

[0391] The evaluation results are shown in Table 5.

[0392] (Anti-spy camera review) Using spindle a1 and spindle a2, precursor knitted fabrics relating to Example 1 were prepared, with the amount of composite tungsten oxide particles used per unit area as shown in Table 6. Furthermore, in Example 1, six precursor knitted fabrics with composite tungsten oxide particle content per unit area ranging from concentration B to concentration G were prepared, as shown in Table 6.

[0393] Subsequently, the precursor knitted fabric was dyed brown with a cationic dye to produce the anti-spycam evaluation knitted fabric of Example 1. Furthermore, the dyeing process was used to obtain the anti-spycam evaluation knitted fabric of Example 1 to prevent the fabric from being transparent under visible light, even in undyed white knitted products.

[0394] In addition, as a reference example, the anti-spycam evaluation knitted fabric involving the reference example was made using only yarn a2 that does not contain composite tungsten oxide particles, in the same manner as the anti-spycam evaluation knitted fabric of this embodiment.

[0395] (Average reflectance of the knitted product in Example 1) Then, using a spectrophotometer manufactured by Hitachi, the reflectance of the knitted fabric involved in Example 1 was measured at 5 nm intervals between wavelengths of 800 nm and 1300 nm, and the average reflectance was calculated. The reflectance measurement results in the wavelength range of 300 nm to 2500 nm are shown below. Figure 16A The average reflectance evaluation results of the fabrics are shown in Table 6.

[0396] (Evaluation of the knitted fabrics in Example 1 and the reference example) Next, the knitted fabrics involved in Example 1 and the Reference Example were evaluated for "prevention of infrared spying (CCD camera see-through)" according to the following test method of the Japan Textile Inspection Association's Boken standard "BQE A 033".

[0397] "Test Methods" (Step 1) Cover the test piece involving the knitted fabric onto the transmission judgment board (visual examination chart) and set it on the test table.

[0398] (Step 2) Use an infrared projector with a beam of approximately 7mW / cm². 2 The intensity of the light is projected onto the surface of the sample.

[0399] (Step 3) Take a normal picture of the above test piece with a digital camera.

[0400] (Step 4) Use an infrared camera to take photos of the above test pieces through the light.

[0401] (Step 5) Confirm the image captured to determine whether infrared light is transmitted.

[0402] "Judgment Result" Infrared transmission was not confirmed in the knitted fabric of Example 1. In contrast, infrared transmission was confirmed in the knitted fabric of the Reference Example.

[0403] [Comparative Example 1] (1) Manufacturing of composite tungsten oxide particles Dissolve 0.216 kg of Cs₂CO₃ in 0.330 kg of water. Add the resulting solution to 1.000 kg of H₂WO₄ and stir thoroughly. Then dry to obtain a dried product. Heat the dried product in an electric furnace with 5% H₂ gas supplied by volume, using N₂ gas as the carrier gas. Calcinate at 800°C for 1 hour. Then switch the gas supply to N₂ gas only and cool to room temperature to obtain the composite tungsten oxide coarse powder of Comparative Example 1.

[0404] (2) Preparation of infrared absorbing particle dispersion 10% by mass of the obtained composite tungsten oxide coarse powder, 10% by mass of acrylic polymeric dispersant (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 together with 0.1 mm diameter zirconia beads in a coating shaker and dispersed for 2 hours to obtain the infrared absorbing particle dispersion of Comparative Example 1. The average particle size (measured by transmission electron microscopy) of the composite tungsten oxide particles in the obtained dispersion of Comparative Example 1 was measured to be 25.1 nm. Furthermore, the average particle size was measured and calculated using the same steps and conditions as in Example 1. Additionally, the dispersion of Comparative Example 1 was aliquoted, and the solvent was removed to obtain the Cs of the composite tungsten oxide particles of Comparative Example 1. 0.33 WO3 particles.

[0405] Figure 9A , Figure 9B The Cs shown is from the composite tungsten oxide particles involved in Comparative Example 1. 0.33 STEM-HAADF image of WO3 particles. Figure 9A Displays a STEM-HAADF image of the entire particle. Additionally, Figure 9B Show magnified view Figure 9A An image of quadrilateral region 91 in the particle shown. The powder, synthesized via a solid-state method, has a fracture surface due to prolonged dispersion processing. Then, since the contrast is affected by the particle thickness, the central region 91 of the particle, which is considered to be less affected by it, was magnified and extracted.

[0406] exist Figure 9B In the diagram, the areas indicated by arrows 92 and 93 confirm the low-contrast region of the Cs column. The defect in this Cs column is considered to be due to the effect of Cs detachment accompanying prolonged crushing processing.

[0407] Figures 10B to 10D Show extraction Figure 10A The results show the line distribution at lines L11 to L13, which form the W / W column, in the STEM-HAADF image. No points were found where the Z-contrast of W atoms fell below 95% of the average contrast. In other words, no W defects were confirmed.

[0408] As for the optical properties of the infrared absorbing particle dispersion relating to Comparative Example 1, the transmittance pattern was measured under the conditions described above. The results of the transmittance pattern show... Figure 11B The transmittance for each wavelength is shown in Table 1.

[0409] Furthermore, the molar absorptivity curve was determined from the absorbance curve obtained during the measurement of the transmittance distribution of the infrared absorbing particle dispersion related to Comparative Example 1. Then, the molar absorptivity curve was separated into three absorption elements: the absorption curve of localized surface plasmon resonance (LSPR⊥) perpendicular to the c-axis, the absorption curve of localized surface plasmon resonance (LSPR / / ) parallel to the c-axis, and the absorption curve of polaron absorption. The results are as follows... Figure 15B As shown.

[0410] Table 2 shows the peak positions, peak intensities, and integrated intensities of the absorption curves involving the three absorption elements. Furthermore, Table 3 shows the ratio of the integrated intensities of the absorption curves for the three absorption elements to the integrated intensities of the molar absorptivity curve.

[0411] Furthermore, the infrared absorbing particle dispersion involved in Comparative Example 1 was diluted to achieve a visible light transmittance of 80%, and the values ​​of L*, a*, and b*, representing colorimetry, were calculated from the spectrophotometer measurement data. The results are shown in Table 4.

[0412] (3) Manufacturing of infrared absorbing fibers Regarding the infrared absorbing particle dispersion involving Comparative Example 1, toluene was removed using a spray dryer to obtain Cs. 0.33 WO3 dispersible powder (B powder).

[0413] The obtained dispersion powder (Powder B) was added to polyethylene terephthalate resin granules, which are thermoplastic resins. After uniform mixing in a mixer, the mixture was melt-kneaded and extruded using a twin-screw extruder. The extruded wire was then cut into granules. Through the above operations, Cs containing heat radiation absorbing components was obtained. 0.33 WO3 particles 40% by mass masterbatch (masterbatch b1).

[0414] Melt spinning masterbatch b1 is then stretched to produce polyester multifilament yarn b1. The resulting polyester multifilament yarn b1 is cut to produce polyester staple fiber b1. The polyester staple fiber b1 is then used to manufacture spun yarn b1.

[0415] (4) Manufacturing of thermal insulation knitted fabrics as fiber products Using yarn b1 and yarn a2 (which does not contain composite tungsten oxide particles) manufactured in Example 1, a fiber product relating to Comparative Example 1, namely knitted product b1, was obtained. Knitted product b1 was manufactured by adjusting the mixing ratio of yarn b1 and yarn a2 to achieve a solar reflectance of 8%.

[0416] (Evaluation of the effect of temperature increase) Next, the temperature rise effect on the back of the fabric of the knitted article b1 was measured under the same conditions as in Example 1.

[0417] The evaluation results are shown in Table 5. According to Table 5, there was no difference in the temperature rise on the back side of the fabric of the knitted products involving Example 1 and Comparative Example 1.

[0418] [Anti-spy camera rating] (Anti-spy camera review) Using spindles b1 and a2, precursor knitted fabrics relating to Comparative Example 1 were prepared, with the amount of composite tungsten oxide particles used per unit area as shown in Table 6. Furthermore, in Comparative Example 1, six precursor knitted fabrics with composite tungsten oxide particle content per unit area ranging from concentration B to concentration G were prepared, as shown in Table 6.

[0419] Subsequently, the precursor knitted fabric was dyed brown with cationic dyes to produce the anti-spy camera evaluation knitted fabric involved in Comparative Example 1.

[0420] The anti-spy camera evaluation knitted fabric obtained in Comparative Example 1 was evaluated under the same conditions as in Example 1. The results of the reflectance measurement are shown below. Figure 16B The average reflectance evaluation results of the fabrics are shown in Table 6.

[0421] Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Figure 11A In the infrared absorbing particle dispersion of Example 1 shown, it can be confirmed that even if the transmittance peak value in the wavelength region of 500nm to 600nm is above 75%, the transmittance trough value in the near-infrared region is below 5%.

[0422] In contrast, Figure 11B In the infrared absorbing particle dispersion of Comparative Example 1 shown, it can be confirmed that when the transmittance peak value in the wavelength region of 500nm to 600nm is 75% or more, the transmittance valley value in the near-infrared region cannot be 5% or less, resulting in poor near-infrared shielding effect.

[0423] Furthermore, as shown in Table 1, the transmittance of the infrared absorbing particle dispersion of Example 1 at a wavelength of 700 nm is higher than that of the infrared absorbing particle dispersion composed of conventional composite tungsten oxide particles from Comparative Example 1, indicating that long-wavelength light in the visible light region (wavelengths from 380 nm to 780 nm) is also transmitted. This suggests that the composite tungsten oxide particles of Example 1 also transmit red light near a wavelength of 800 nm, thus contributing to the improvement of the hue of conventional composite tungsten oxide particles.

[0424] Table 4 shows that the b* value of the infrared absorbing particle dispersion of Example 1 is -0.61502, while the b* value of the near-infrared absorbing particle dispersion of Comparative Example 1 is -0.71411. A more negative b* value indicates a more bluish tint to the dispersion. This suggests that Example 1 has less blue than existing composite tungsten oxide particles, which also contributes to improved color tone.

[0425] Based on the results shown in Table 6, in the knitted fabric used for anti-spy camera evaluation related to Example 1, it can be confirmed that even with a unit area content of 0.09 g / m² of composite tungsten oxide particles... 2 Furthermore, no penetration was confirmed in tests conducted by the Japan Textile Inspection Association. In contrast, in the knitted fabric used for anti-spy camera evaluation in Comparative Example 1, it was confirmed that if the unit area content of composite tungsten oxide particles were not 0.13 g / m², penetration would not be detected. 2 The above will not produce the effect of not being confirmed to have been passed.

[0426] In addition, in comparison Figure 16A , Figure 16B The following points can be confirmed. In Figure 16A The reflectance curve of the knitted fabric used for anti-spy camera evaluation in Example 1, as shown, shows that even with a unit area content of 0.09 g / m² of composite tungsten oxide particles... 2 At concentration B, the reflectivity at a wavelength of 1050 nm is also below 65%. In contrast, at... Figure 16B The reflectance curve of the knitted fabric used for anti-spy camera evaluation in Comparative Example 1 is shown, with a composite tungsten oxide particle content of 0.09 g / m². 2 At a concentration of B, the reflectivity exceeds 65% at a wavelength of 1050 nm.

[0427] Based on these results, it can be seen that the composite tungsten oxide particles contained in the infrared absorbing fiber of this embodiment have superior infrared absorption characteristics compared to previously known composite tungsten oxide particles.

[0428] This application claims priority based on Japanese Patent Application No. 2023-170834, filed with the Japanese Patent Office on September 29, 2023, and incorporates the entire contents of Japanese Patent Application No. 2023-170834 in this international application.

[0429] Explanation of reference numerals in the attached figures 10 Composite Material Manufacturing Equipment 11 Storage Department 12 Dual-fluid nozzles 13 Reaction tubes 131 Piping 14 Filters 15 Injectors 20 Reduction Processing Unit 21 Reaction tube 21A One port 21B Another port 22 Heaters 23 Containers 24 Composite Tungsten Oxide Particles 30 Infrared Absorbing Particle Dispersion 31 Infrared Absorbing Particles 32 Liquid medium 40 Infrared Absorbing Fibers 41 Fibers 42 Composite tungsten oxide particles 41A surface 41B Interior CA central axis 501 W / W column 502 W / Cs column 51 W atoms 52 O atoms 53 M elements 54 Octahedron 55 gap Area 71 L1~L6 lines Points P1 to P15 Area 91 Arrows 92 and 93 Lines L11 to L13 121 Defective surface 122 Space

Claims

1. An infrared absorbing fiber, comprising fibers, and Composite tungsten oxide particles are disposed at more than one selected location from the interior and surface of the fiber. The composite tungsten oxide particles contain composite tungsten oxide. The composite tungsten oxide is of the general formula M x W y O z This indicates that element M is one or more elements selected from alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I. W represents tungsten, O represents oxygen, and 0.20 ≤ x / y ≤ 0.37, 2.2 ≤ z / y ≤ 3.

3. The crystal system is hexagonal. In the STEM-HAADF image of the composite tungsten oxide particles incident from [001], there are spots containing 0.01% to 10% by number of which have a Z contrast of tungsten atoms reduced to less than 95% of the average value.

2. The infrared absorbing fiber according to claim 1, wherein the M element of the composite tungsten oxide comprises one or more elements selected from 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, having a defect surface in a direction perpendicular to the c-axis in a STEM-HAADF image of the composite tungsten oxide particles incident from [110].

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

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

7. The infrared absorbing fiber according to claim 5, wherein the semi-synthetic fiber is selected from one or more of cellulose-based fibers, protein-based fibers, chlorinated rubber, and hydrochloric acid rubber.

8. The infrared absorbing fiber according to claim 5, wherein the natural fiber is selected from one or more of plant fibers, animal fibers, and mineral fibers.

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

10. The infrared absorbing fiber according to claim 5, wherein the inorganic fiber is selected from one or more of metal fibers, carbon fibers, and silicate fibers.

11. A fiber product comprising the infrared absorbing fiber as described in claim 1 or 2.

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