Infrared absorbing particles, infrared absorbing particle dispersion, infrared absorbing particle dispersion, infrared absorbing bonded transparent substrate, infrared absorbing transparent substrate

Abstract

Infrared absorbing particles containing composite tungsten oxide particles, wherein the composite tungsten oxide particles have a hexagonal crystal structure and are infrared absorbing particles of composite tungsten oxide represented by the general formula MxWyOz (wherein M is one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, Fe, W is tungsten, O is oxygen, 0.25≤x / y≤0.39, 2.70≤z / y≤2.90).

Description

Technology Field

[0001] The present invention relates to infrared absorbing particles, an infrared absorbing particle dispersion, an infrared absorbing particle dispersion, an infrared absorbing bonded transparent substrate, and an infrared absorbing transparent substrate. Background Technology

[0002] As a method to remove or reduce heat components from external light sources such as sunlight or light bulbs, conventional practices have involved forming a coating containing a material that reflects infrared rays on a glass surface to create heat-reflecting glass. Furthermore, the material contains FeO x , CoO x , CrO x , TiO x Metal oxides such as Ag, Au, Cu, Ni, and Al have been used.

[0003] However, since these metal oxides or metal materials have the property of simultaneously reflecting or absorbing visible light in addition to infrared light, which contributes significantly to the thermal effect, there was a problem in that the visible light transmittance of the heat-reflecting glass was reduced. In particular, since high transmittance in the visible light region is required for substrates used in building materials, vehicles, telephone boxes, etc., when using materials such as the metal oxides mentioned above, the film thickness had to be made very thin. For this reason, a method has been adopted to deposit a thin film with a thickness of 10 nm at the level of a physical film deposition method using spray baking, CVD, sputtering, or vacuum deposition.

[0004] However, these film deposition methods require large-scale equipment or vacuum facilities, and have drawbacks such as difficulties in productivity and large-area production, as well as high manufacturing costs. In addition, when using these materials to increase solar shading characteristics, there is a tendency for the reflectance of light in the visible light region to increase simultaneously, and there is also a drawback of impairing the aesthetics by giving a shiny, mirror-like appearance.

[0005] To improve these problems, it is considered necessary to have a film with low reflectance in the visible light region and high reflectance in the infrared region as physical properties.

[0006] Antimony tin oxide (hereinafter abbreviated as ATO) and indium tin oxide (hereinafter abbreviated as ITO) are known as materials that possess high visible light transmittance and excellent solar shielding capabilities. Since these materials have relatively low visible light reflectivity, they do not provide a shiny appearance. However, because the plasma frequency is in the near-infrared region, the reflection and absorption effects are not yet sufficient for light in the near-infrared region, which is closer to the visible light region. Furthermore, these materials have a problem in that, due to their low solar shielding power per unit weight, achieving high shielding capabilities requires a large amount of material, resulting in relatively high costs.

[0007] In addition, as infrared shielding materials with solar radiation shielding capabilities, slightly reduced tungsten oxide, molybdenum oxide, and vanadium oxide films can be cited. These films are materials that can be used as so-called electrochromic materials; however, they are transparent when sufficiently oxidized, and when reduced by electrochemical methods, they generate absorption across the spectrum from the long-wavelength visible light region to the near-infrared region.

[0008] In Patent Document 1, a heat-blocking glass is proposed, characterized by having a first dielectric film as a first layer on a transparent glass substrate from the substrate side, a composite tungsten oxide film containing at least one metal element selected from the group consisting of groups IIIa, IVa, Vb, VIb, and VIIb of the periodic table as a second layer on the first layer, and a second dielectric film as a third layer on the second layer.

[0009] In Patent Document 2, an ultraviolet heat ray blocking glass is proposed, characterized by being formed by providing, on a transparent glass substrate, a first transparent dielectric film having an oxide having ultraviolet blocking performance having at least one component selected from the group consisting of zinc, cerium, titanium, and cadmium, a composite oxide of these, or a composite oxide having a trace amount of metal element added to these oxides as a first layer from the substrate side, providing a second transparent dielectric film as a second layer on the first layer, providing a composite tungsten oxide film containing at least one metal element selected from the group consisting of groups IIIa, IVa, Vb, VIb, and VIIb of the periodic table as a third layer on the second layer, and providing a third transparent dielectric film as a fourth layer on the third layer.

[0010] In Patent Document 3, a heat-blocking glass is proposed, characterized by having a composite tungsten oxide film containing at least one metal element selected from the group consisting of groups IIIa, IVa, Vb, VIb, and VIIb of the periodic table provided as a first layer on a transparent substrate from the substrate side, and a transparent dielectric film provided as a second layer on the first layer.

[0011] Patent Document 4 proposes a method for depositing a tungsten oxide film in a gas phase, characterized by using a target containing tungsten and sputtering in an atmosphere containing carbon dioxide. According to this deposition method, it is disclosed that a tungsten oxide film having high thermal insulation and uniform optical properties within the plane can be stably produced.

[0012] For example, as described in Patent Documents 1 to 4, the sputtering method has been used conventionally as a method for manufacturing an infrared shielding layer containing a tungsten compound. However, this physical film deposition method requires large-scale equipment or vacuum facilities, which presents challenges in terms of productivity, and while it is technically possible to perform large-area expansion, there is also the challenge that the manufacturing cost of the film increases.

[0013] Therefore, the applicant, in Patent Document 5, general formula W which transmits light in the visible light region and absorbs light in the infrared region y O x Tungsten oxide microparticles denoted by , or general formula M x W y O z An infrared shielding material fine particle dispersion formed by dispersing composite tungsten oxide fine particles, denoted as [ ], in a medium, an infrared shielding material, a method for manufacturing infrared shielding material fine particles, and infrared shielding material fine particles are disclosed.

[0014] In addition, the applicant, in Patent Document 6, [document] general formula W which transmits light in the visible light region and absorbs light in the infrared region. y O x Tungsten oxide microparticles denoted by or general formula M x W y O z A method for manufacturing tungsten oxide microparticles for forming a solar ray shield, which are composite tungsten oxide microparticles denoted as [], and tungsten oxide microparticles for forming a solar ray shield were disclosed.

[0015] As disclosed in Patent Documents 5 and 6, a solar shield containing tungsten oxide microparticles, etc., does not require large-scale equipment or vacuum facilities such as physical film deposition methods, and can be produced at a low cost with high productivity. In addition, from the perspective of the characteristics of the solar shield, a solar shield containing tungsten oxide microparticles, etc., can further improve light transmittance in the visible light region without reducing infrared shielding performance. Prior art literature

[0016] Japanese Patent Publication No. Hei 8-12378 Japanese Patent Publication No. Hei 8-59301 Japanese Patent Publication No. Hei 8-283044 Japanese Patent Publication No. Hei 10-183334 Japanese Patent No. 4096205 Japanese Patent No. 4626284 The problem to be solved

[0017] However, the conventional general formula W y O x Tungsten oxide microparticles denoted by or general formula M x W y O z Optical components (films, resin sheets, etc.) containing composite tungsten oxide microparticles, denoted as [label], exhibited a characteristic blue color of tungsten oxide. For this reason, depending on the application, it was required to have a lighter color.

[0018] In addition, infrared absorbing materials may be exposed to high temperature and high humidity environments caused by heat from sunlight or atmospheric moisture during use. For this reason, infrared absorbing materials are required to have excellent weather resistance, meaning that the degradation of infrared absorption characteristics (solar shading characteristics) is suppressed even when exposed to high temperature and high humidity environments.

[0019] Taking into account the problems of the prior art described above, one aspect of the present invention aims to provide infrared absorbing particles that are light blue in color and have excellent weather resistance and infrared absorption characteristics. means of solving the problem

[0020] In one aspect of the present invention, the infrared absorbing particle contains composite tungsten oxide particles, and

[0021] The above composite tungsten oxide particles have a hexagonal crystal structure and general formula M x W y O z (wherein M is one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, Fe, W is tungsten, O is oxygen, 0.25≤x / y≤0.39, 2.70≤z / y≤2.90) provides infrared absorbing particles that are particles of a composite tungsten oxide. Effects of the invention

[0022] In one aspect of the present invention, infrared absorbing particles that are light blue and have excellent weather resistance and infrared absorption characteristics can be provided. Brief explanation of the drawing

[0023] Figure 1 is a schematic diagram of an infrared absorbing particle dispersion. Figure 2 is a schematic diagram of an infrared absorbing particle dispersion. Figure 3 is a schematic cross-sectional view of an infrared absorption bonded transparent substrate. Figure 4 is a schematic cross-sectional view of an infrared-absorbing transparent substrate. Figure 5 is the XRD pattern of the infrared absorbing particles obtained in Example 3. Figure 6 is the XRD pattern of infrared absorbing particles obtained in Comparative Examples 1 and 2. Specific details for implementing the invention

[0024] Specific examples of infrared absorbing particles, infrared absorbing particle dispersions, infrared absorbing particle dispersions, infrared absorbing bonded transparent substrates, and infrared absorbing transparent substrates according to one embodiment of the present disclosure (hereinafter referred to as "the present embodiment") are described below. Furthermore, the present invention is not limited to these examples, and is intended to include all modifications within the meaning and scope equivalent to the claims, as defined by the claims.

[0025] Hereinafter, embodiments for carrying out the present invention will be described in the following order: 1. infrared absorbing particles, 2. a method for manufacturing infrared absorbing particles, 3. an infrared absorbing particle dispersion, 4. an infrared absorbing particle dispersion, 5. an infrared absorbing bonded transparent substrate, 6. an infrared absorbing transparent substrate, and 7. physical properties.

[0026] 1. Infrared absorbing particles

[0027] The infrared absorbing particles according to the present embodiment may contain composite tungsten oxide particles. Additionally, the infrared absorbing particles of the present embodiment may be composed solely of composite tungsten oxide particles, but even in this case, the inclusion of unavoidable impurities is not excluded.

[0028] Composite tungsten oxide particles are of general formula M x W y O z It can be made of particles of complex tungsten oxide denoted as .

[0029] In the above general formula, the element M can be one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, and Fe, W can be tungsten, and O can be oxygen. x, y, and z can satisfy 0.25≤x / y≤0.39 and 2.70≤z / y≤2.90.

[0030] The above composite tungsten oxide particles may have a hexagonal crystal structure.

[0031] (Regarding the composition, crystal structure, and lattice constant of complex tungsten oxide particles)

[0032] In the above general formula for composite tungsten oxide particles, the value of x / y, representing the amount of element M added, is preferably 0.25 or higher and 0.39 or lower, and more preferably 0.25 or higher and 0.32 or lower. This is because if the value of x is 0.25 or higher and 0.39 or lower, composite tungsten oxide particles with hexagonal crystals are easy to obtain, and the infrared absorption effect is sufficiently manifested. In addition to hexagonal composite tungsten oxide particles, the infrared absorbing particles may be tetragonal or M 0.36 WO 3.18 (Cs4W 11 O 35 Although there are cases containing orthorhombic precipitates (e.g.), these precipitates do not affect the infrared absorption effect. In the composite tungsten oxide particles, theoretically, it is thought that the added M element is placed in all hexagonal pores at the point where the x / y value becomes 0.33.

[0033] In addition, it is preferable that the value of z / y in the above general formula be 2.70 ≤ z / y ≤ 2.90. By making the value of z / y 2.70 or higher, it is possible to produce infrared absorbing particles that are light blue and have excellent weather resistance and infrared absorption characteristics. Furthermore, by making the value of z / y 2.70 or higher, the light transmittance at a wavelength of 850 nm can be increased, for example. With the increase in the functionality of automobiles, vehicle-mounted devices and sensors that perform control using infrared communication waves are widely used. In order to increase the precision of control of these various vehicle-mounted devices and the detection precision of sensors, it is also required to design a high light transmittance at a wavelength of 850 nm. Since the infrared absorbing particles of the present embodiment have excellent light transmittance at a wavelength of 850 nm as described above, the precision of control of vehicle-mounted devices and detection of sensors can be increased in automobiles, etc., in which an infrared absorbing particle dispersion using said infrared absorbing particles is placed in an opening such as a window.

[0034] By making the z / y value 2.90 or less, a sufficient amount of free electrons are generated to increase the absorption and reflection characteristics in the infrared region, thereby enabling the creation of high-efficiency infrared absorption particles.

[0035] In addition, it does not matter if some of the oxygen in the composite tungsten oxide particles is replaced by other elements. Examples of such other elements include nitrogen, sulfur, halogens, etc.

[0036] It is desirable for the composite tungsten oxide particles to have a hexagonal crystal structure. This is because when the composite tungsten oxide particles have 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 or the infrared absorbing particles containing the composite tungsten oxide particles are particularly enhanced.

[0037] In addition, if one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, and Fe are used in the M element, it becomes easier to form a hexagon. For this reason, it is desirable for the M element to include one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, and Fe.

[0038] The lattice constant of the composite tungsten oxide particles is not particularly limited, but, for example, it is preferable that the a-axis be 7.3850 Å or larger and 7.4186 Å or smaller, and the c-axis be 7.5600 Å or larger and 7.6240 Å or smaller. Infrared absorbing particles containing composite tungsten oxide particles may be ground to obtain a desired particle size as described below, but it is preferable that the lattice constant of the composite tungsten oxide particles before and after grinding satisfy the above range.

[0039] (Regarding particle size)

[0040] The particle size of the infrared absorbing particles of the present embodiment can be selected according to the infrared absorbing particles, infrared absorbing particle dispersion, infrared absorbing particle dispersion, infrared absorbing bonded transparent substrate, or the purpose of use of the infrared absorbing transparent substrate, and is not particularly limited.

[0041] The average dispersion particle size of the infrared absorbing particles is preferably, for example, 1 nm or more and 800 nm or less, and more preferably 1 nm or more and 400 nm or less. This is because if the average dispersion particle size is 800 nm or less, strong infrared absorption ability can be exerted by the infrared absorbing particles, and if the average dispersion particle size is 1 nm or more, industrial manufacturing is easy.

[0042] In particular, when the average dispersion particle size is 400 nm or less, it is possible to avoid the infrared absorption film or molded body (plate, sheet) becoming a gray color with monotonously reduced transmittance. In addition, by making the average dispersion particle size 400 nm or less, when the infrared absorption particle dispersion liquid is used to form an infrared absorption particle dispersion, the transmission of visible light can be increased by suppressing haze in particular.

[0043] When using an infrared absorbing particle dispersion, etc., for applications requiring light transparency in the visible light region, it is desirable for the infrared absorbing particles to have an average dispersion particle size of 40 nm or less. Here, the average dispersion particle size is defined as the 50% volume cumulative particle size measured using the DLS-8000 manufactured by Otsuka Denshi Co., Ltd., which is based on the principle of dynamic light scattering. This is because if the infrared absorbing particles have an average dispersion particle size smaller than 40 nm, light scattering caused by Mie scattering and Rayleigh scattering of the infrared absorbing particles is sufficiently suppressed, thereby maintaining high light visibility in the visible light region while simultaneously maintaining transparency efficiently. When used for applications requiring particular transparency, such as windproofing for automobiles, it is more desirable to make the average dispersion particle size of the infrared absorbing particles 30 nm or less, and even more desirable to make it 25 nm or less, in order to further suppress scattering.

[0044] The particle size of the composite tungsten oxide particles regarding the infrared absorbing particles described above can be appropriately selected according to the intended use of the infrared absorbing film, infrared absorbing particle dispersion, infrared absorbing transparent substrate, or infrared absorbing bonded transparent substrate manufactured using said composite tungsten oxide particles or their dispersion, and is not particularly limited. It is preferable that the particle size of such composite tungsten oxide particles be 1 nm or larger and 800 nm or smaller. Furthermore, when transparency is prioritized, it is preferable that the particle size of the composite tungsten oxide particles be 200 nm or smaller, and more preferably 100 nm or smaller. This is because if the particle size is large, light in the visible light region with wavelengths of 380 nm to 780 nm is scattered by geometric scattering or Mie scattering, causing the appearance of the infrared absorbing material to become cloudy like glass, making it difficult to obtain clear transparency. When the particle size becomes 200 nm or smaller, the above scattering is reduced, and it becomes the Rayleigh scattering region. In the Rayleigh scattering region, since scattered light is reduced in proportion to the sixth power of the particle size, scattering is reduced along with a decrease in particle size, thereby improving transparency. Furthermore, it is desirable that the scattered light is very small when the particle size is 100 nm or less. As mentioned above, excellent infrared absorption characteristics can be exhibited by the composite tungsten oxide particles according to the present embodiment when the particle size is 800 nm or less, and industrial manufacturing is easy when the particle size is 1 nm or more.

[0045] The particle size here can be calculated by measuring the particle sizes of multiple particles using a transmission electron microscope (TEM), for example, while the composite tungsten oxide particles are dispersed. Additionally, since composite tungsten oxide particles are typically irregular in shape, the diameter of the smallest circle circumscribing the particle can be defined as the particle size. For example, when the particle sizes of multiple particles are measured individually using a transmission electron microscope as described above, it is desirable that the particle sizes of all particles satisfy the above range. The number of particles to be measured is not particularly limited, but it is desirable to be, for example, between 10 and 50.

[0046] (About color)

[0047] The infrared absorbing particle of the present embodiment has a hue L when only light absorption by said infrared absorbing particle is calculated. * a * b * b in the color system * It is desirable to satisfy >0.

[0048] This is the hue when only the light absorption of infrared absorbing particles is calculated, L * a * b * b in the color system * This is because it can be made light blue by satisfying >0.

[0049] Calculating only the light absorption by infrared absorbing particles means that when performing the evaluation, a measurement of the blank is also performed, and by subtracting the evaluation result of the blank from the evaluation result of the infrared absorbing particles, the influence of light reflection caused by the cell, etc., used during the measurement is eliminated.

[0050] (Regarding the covering)

[0051] Infrared absorbing particles may undergo surface treatment for purposes such as surface protection, improved durability, prevention of oxidation, and improved water resistance. Although the specific details of the surface treatment are not particularly limited, for example, the surface of the infrared absorbing particles of the present embodiment may be coated with a compound containing one or more atoms selected from Si, Ti, Zr, and Al. That is, the infrared absorbing particles may have a coating by the said compound. In this case, one or more compounds selected from oxides, nitrides, carbides, etc. may be examples of compounds containing one or more atoms selected from Si, Ti, Zr, and Al.

[0052] 2. Method for manufacturing infrared absorbing particles

[0053] According to the method for manufacturing infrared absorbing particles of the present embodiment, infrared absorbing particles as described above can be manufactured. For this reason, the description of previously explained matters is omitted.

[0054] The inventor of the present invention has investigated a method for manufacturing infrared absorbing particles that are light blue in color and have excellent weather resistance and infrared absorption characteristics.

[0055] Furthermore, the weather resistance referred to here means, for example, an infrared-absorbing particle dispersion, the ability to suppress the degradation of solar shading characteristics when placed in high-temperature or high-humidity environments.

[0056] As a result, it was discovered that infrared absorbing particles capable of solving the above problem can be obtained by performing the following first heat treatment process and second heat treatment process on a predetermined raw material, and the present invention was completed.

[0057] The first heat treatment process (oxidizing gas heat treatment process) is a process of heat treatment performed under an atmosphere of a first gas containing at least an oxygen source.

[0058] The second heat treatment process (non-oxidizing gas heat treatment process) is a process of heat treatment under an atmosphere of a second gas containing one or more types selected from reducing gas and inert gas.

[0059] In addition, the order in which the first heat treatment process and the second heat treatment process are performed is not particularly limited; for example, the second heat treatment process may be performed after the first heat treatment process, or the first heat treatment process may be performed after the second heat treatment process.

[0060] Here, the raw material powder provided for heat treatment is described, and then the heat treatment conditions are described in detail.

[0061] (1) Raw material powder

[0062] Here, raw material powder is one or more types selected from a mixture of tungstic acid (H2WO4) or a mixture of tungstic acid and a compound containing element M, and a dry powder of a mixture of tungstic acid (H2WO4) or a mixture of tungstic acid and a solution containing element M.

[0063] The above tungstic acid mixture is a mixture of tungstic acid (H2WO4) and tungsten oxide.

[0064] The above mixed powder and dry powder are described.

[0065] (Mixed powder)

[0066] As described above, a mixed powder can be used as the raw material powder. For example, a mixed powder of tungstic acid and a compound containing M element, or a mixed powder of tungstic acid and a compound containing M element can be used.

[0067] Here, the tungstic acid (H2WO4) used in the raw material powder is not particularly limited as long as it becomes an oxide upon calcination. In addition, the tungsten oxide used in the tungstic acid mixture may be any of W2O3, WO2, or WO3.

[0068] In addition, the M element-containing compound used to add M element by mixing with tungstic acid or a mixture of tungstic acid is preferably one or more selected from oxides, hydroxides, and carbonates. For this reason, the M element-containing compound is preferably one or more selected from oxides of M element, hydroxides of M element, and carbonates of M element.

[0069] In addition, it is preferable that the M element be one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, and Fe.

[0070] The mixing of tungstic acid (H2WO4) or a mixture of tungstic acid and a compound containing element M can be carried out using a commercially available grinder, kneader, ball mill, sand mill, paint shaker, etc. (mixing process).

[0071] (Dry powder)

[0072] In addition, as a raw material powder, a dry powder of a mixed solution of tungstic acid (H2WO4) or a mixture of tungstic acid and a solution containing M element can be used.

[0073] As tungstic acid and tungstic acid mixtures have been explained in the section on mixtures, they will be omitted here.

[0074] It is preferable that the solution containing the element M be one or more types selected from an aqueous solution of a metal salt of the element M, a colloidal solution of a metal oxide of the element M, and an alkoxy solution of the element M.

[0075] The types of metal salts used in aqueous solutions of metal salts of element M are not particularly limited, and examples include nitrates, sulfates, chlorides, carbonates, etc.

[0076] In addition, the drying temperature or time when manufacturing the dry powder is not specifically limited.

[0077] It is preferable that the raw material powder contains tungsten and element M in a ratio according to the target composition. For example, it is preferable that the raw material powder contains element M (M) and tungsten (W) in a molar ratio such that M / W is 0.25 or more and 0.39 or less.

[0078] (2) Heat treatment process

[0079] The method for manufacturing infrared absorbing particles of the present embodiment may include a first heat treatment process for heat-treating raw powder as previously described and a second heat treatment process.

[0080] (2-1) First heat treatment process

[0081] The first heat treatment process (oxidizing gas heat treatment process) is a process of heat treatment performed under an atmosphere of a first gas containing at least an oxygen source.

[0082] The oxygen source gas is not particularly limited, but one or more types selected from oxygen gas, air gas, and water vapor are preferred.

[0083] Gases other than the oxygen source of the first gas are not particularly limited, but may contain, for example, an inert gas. The inert gas is not particularly limited and may use one or more gases selected from nitrogen, argon, helium, etc.

[0084] The concentration of the oxygen source in the first gas can be appropriately selected according to the heat treatment temperature or the volume of material being heat-treated and is not particularly limited; however, since excessive oxidation may reduce the infrared absorption function, it is desirable to set the concentration to one that oxidizes only the surface of the particles.

[0085] The temperature during heat treatment can be appropriately selected depending on the amount of raw material powder to be heat treated, etc., and is not particularly limited. For example, it is preferable to be 400°C or higher and 850°C or lower.

[0086] By performing an oxidation treatment in the first heat treatment process, for example, the surface of the composite tungsten oxide particles can be oxidized to make them polaron-absorbing free. By performing the first heat treatment process, the transmittance of the wavelength of infrared communication waves is increased, and infrared absorbing particles that are light blue and have high weather resistance (heat resistance and moisture resistance) are obtained.

[0087] The first heat treatment process may be carried out in a single step, but it may also be carried out in multiple steps in which the atmosphere or temperature is changed during the heat treatment. For example, in the first step, heat treatment may be carried out at a temperature of 400°C or higher and 850°C or lower under a mixed gas atmosphere of an inert gas and an oxygen source gas, and in the second step, heat treatment may be carried out at a temperature of 400°C or higher and 850°C or lower under an inert gas atmosphere. By carrying out the first heat treatment process in multiple steps in this way, infrared absorbing particles having particularly excellent infrared absorption capabilities can be obtained.

[0088] (2-2) Second heat treatment process

[0089] The second heat treatment process (non-oxidizing gas heat treatment process) is a process of heat treatment under an atmosphere of a second gas containing one or more types selected from reducing gas and inert gas.

[0090] By performing a second heat treatment process, oxygen vacancies can be formed in the infrared absorbing particles.

[0091] As previously explained, the atmosphere during heat treatment in the second heat treatment process may be an inert gas alone, a reducing gas alone, or a mixed gas of an inert gas and a reducing gas.

[0092] As an inert gas, one or more gases selected from nitrogen, argon, helium, etc., can be used without being particularly limited.

[0093] The reducing gas is not specifically limited, and one or more gases selected from, for example, hydrogen, alcohol, etc. may be used.

[0094] When a mixed gas of an inert gas and a reducing gas is used as the second gas, the concentration of the reducing gas in the inert gas can be appropriately selected according to the heat treatment temperature or the amount of raw material powder to be heat treated, and is not particularly limited. The concentration of the reducing gas in the second gas is preferably, for example, 20 volume% or less, more preferably 10 volume% or less, and even more preferably 7 volume% or less.

[0095] This is because by keeping the concentration of the reducing gas in the second gas at 20 volume% or less, the generation of WO2 or W, which do not have an infrared shielding function due to rapid reduction, can be avoided.

[0096] When using a mixed gas as the second gas, the lower limit of the concentration, i.e., the content ratio of the reducing gas in the second gas is not specifically limited, but it is preferable that the content ratio of the reducing gas in the second gas exceeds 1 volume%. This is because if the content ratio of the reducing gas in the second gas exceeds 1 volume%, oxygen vacancies can be generated more reliably.

[0097] The temperature during heat treatment in the second heat treatment process can be appropriately selected according to the atmosphere or the amount of raw material powder to be heat treated, and is not particularly limited. When the atmosphere is an inert gas alone, from the perspective of crystallinity or coloring power, a temperature of 400°C or higher and 1200°C or lower is preferable, a temperature of 500°C or higher and 1000°C or lower is more preferable, and a temperature of 500°C or higher and 900°C or lower is even more preferable. Even when the second gas includes a reducing gas, the second heat treatment temperature is not particularly limited, but, for example, the above temperature range, which is the same as when the second gas is an inert gas alone, may be a suitable range.

[0098] The second heat treatment process may be carried out in a single step, but it may also be carried out in multiple steps in which the atmosphere or temperature is changed during the heat treatment. For example, in the first step, heat treatment may be performed at 400°C or higher and 850°C or lower under a mixed gas atmosphere of an inert gas and a reducing gas, and in the second step, heat treatment may be performed at 800°C or higher and 1000°C or lower under an inert gas atmosphere. By carrying out the second heat treatment process in multiple steps in this way, infrared absorbing particles having particularly excellent infrared absorption capabilities can be obtained.

[0099] The heat treatment time in the second heat treatment process is not specifically limited and can be appropriately selected according to the heat treatment temperature, atmosphere, and amount of raw material powder to be heat treated, but for example, it may be from 5 minutes to 7 hours.

[0100] By carrying out the heat treatment process described above, the infrared absorbing particles described above can be obtained. In addition, the method for manufacturing infrared absorbing particles according to the present embodiment may include a grinding process to grind the infrared absorbing particles to obtain a desired particle size, or a sieving process, if necessary.

[0101] (3) Formula process

[0102] As previously explained, the infrared absorbing particles may have their surfaces modified with a compound containing one or more atoms selected from Si, Ti, Zr, and Al. Thus, the method for manufacturing infrared absorbing particles may further include a modification process, for example, in which the infrared absorbing particles are modified with a compound containing one or more atoms selected from Si, Ti, Zr, and Al.

[0103] In the modification process, the specific conditions for modifying the infrared absorbing particles are not particularly limited. For example, a modification process may be performed to form a film on the surface of the infrared absorbing particles by adding an alkoxide containing one or more types of metals selected from the metal group above to the infrared absorbing particles being modified.

[0104] 3. Infrared absorbing particle dispersion

[0105] The infrared absorbing particle dispersion of the present embodiment may contain a liquid medium and infrared absorbing particles as described above. Specifically, for example, as schematically illustrated in FIG. 1, the infrared absorbing particle dispersion (10) may have a liquid medium (12) and infrared absorbing particles (11) as described above. It is preferable that the infrared absorbing particles (11) as described above be placed in the liquid medium (12) and dispersed within the liquid medium (12). Furthermore, FIG. 1 is a schematic drawing, and the infrared absorbing particle dispersion of the present embodiment is not limited to this form. For example, although the infrared absorbing particles (11) are described as spherical particles in FIG. 1, the shape of the infrared absorbing particles (11) is not limited to this form and may have any shape. As described above, the infrared absorbing particles (11) may have a coating on their surface, for example. The infrared absorbing particle dispersion (10) may include other additives as needed, in addition to the infrared absorbing particles (11) and the liquid medium (12).

[0106] (1) Regarding the components contained

[0107] As described above, the infrared absorbing particle dispersion of the present embodiment may contain a liquid medium and infrared absorbing particles as previously described. Since infrared absorbing particles have already been described, a description thereof is omitted. Below, a dispersant, etc., that may contain the liquid medium and the infrared absorbing particle dispersion as needed will be described.

[0108] (1-1) Regarding liquid media

[0109] The liquid medium is not specifically limited, and various liquid media can be used. For example, one type selected from the group of liquid medium materials including water, organic solvents, oils and fats, liquid resins, and liquid plasticizers for plastics, or a mixture of two or more types selected from the group of liquid medium materials can be used.

[0110] As organic solvents, various types can be selected, such as alcohol-based, ketone-based, ester-based, amide-based, hydrocarbon-based, and glycol-based solvents. Specifically, alcohol-based solvents such as methanol, ethanol, 1-propanol, isopropanol (isopropyl alcohol), butanol, pentanol, benzyl alcohol, diacetone alcohol, and 1-methoxy-2-propanol; ketone-based solvents such as dimethyl ketone, acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ester-based solvents such as 3-methyl-methoxy-propionate and butyl acetate; and glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate; Examples include 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 ethylene chloride and chlorobenzene. Among these, organic solvents with low polarity are preferred, and in particular, isopropyl alcohol, ethanol, 1-methoxy-2-propanol, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, and n-butyl acetate are more preferred. These solvents may be used in combination of one or more types. Additionally, if necessary, an acid or an alkali may be added to adjust the pH.

[0111] As for the oil, one or more types selected from drying oils such as linseed oil, sunflower oil, and tung oil; semi-drying oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil, and rice bran oil; non-drying oils such as olive oil, coconut oil, palm oil, and dehydrated castor oil; fatty acid monoesters obtained by directly esterifying a fatty acid of vegetable oil with a monoalcohol; ethers; isopha (registered trademark) E, exol (registered trademark) hexane, heptane, E, D30, D40, D60, D80, D95, D110, and D130 (all from ExxonMobil) may be used.

[0112] As a liquid resin, monomers or oligomers that are cured by polymerization, such as methyl methacrylate or styrene, thermoplastic resins, etc., can be used by dissolving them in a liquid medium.

[0113] Preferred examples of liquid plasticizers for plastics include plasticizers that are compounds of monohydric alcohols and organic acid esters, ester-based plasticizers such as polyhydric alcohol organic acid ester compounds, and phosphate-based plasticizers such as organic phosphate-based plasticizers. Among these, triethylene glycol di-2-ethylhexanoate, triethylene glycol di-2-ethylbutyrate, and tetraethylene glycol di-2-ethylhexanoate are more preferred because they have low hydrolytic properties.

[0114] (1-2) Dispersants, coupling agents, surfactants

[0115] The infrared absorbing particle dispersion of the present embodiment may contain one or more types selected from a dispersant, a coupling agent, and a surfactant as needed.

[0116] Dispersants, coupling agents, and surfactants can be selected according to the application, but materials having amine-containing groups, hydroxyl groups, carboxyl groups, or epoxy groups as functional groups can be suitably used.

[0117] The above functional group adsorbs to the surface of infrared absorbing particles to prevent aggregation of infrared absorbing particles, and even when used as, for example, an infrared absorbing film, has the effect of particularly uniformly dispersing the infrared absorbing particles within the infrared absorbing film.

[0118] The infrared absorbing particle dispersion of the present embodiment may include a dispersant. Such dispersants include coupling agents or surfactants that function as dispersants. Suitable dispersants include one or more selected from phosphate ester compounds, polymer-based dispersants, silane-based coupling agents, titanate-based coupling agents, aluminum-based coupling agents, etc., but are not limited to these.

[0119] As polymeric dispersants, one or more types selected from acrylic polymeric dispersants, urethane polymeric dispersants, acrylic block copolymer polymeric dispersants, polyether dispersants, polyester polymeric dispersants, etc. may be cited.

[0120] The amount of the dispersant added is preferably in the range of 10 parts by mass or more and 1,000 parts by mass or less, per 100 parts by mass of infrared absorbing particles, and more preferably in the range of 20 parts by mass or more and 200 parts by mass or less. When the amount of the dispersant added is within the above range, the infrared absorbing particles do not aggregate in the liquid medium, and dispersion stability can be particularly maintained.

[0121] (2) Method for adding infrared absorbing particles to a liquid medium

[0122] The method of adding infrared absorbing particles to a liquid medium is not particularly limited, but it is preferable to use a method that can uniformly disperse the infrared absorbing particles within the liquid medium.

[0123] For example, one or more types selected from bead mills, ball mills, sand mills, paint shakers, ultrasonic homogenizers, etc. may be cited.

[0124] Through dispersion treatment using these dispersion means, the infrared absorbing particles are dispersed into a liquid medium, and simultaneously, micronization by collisions between the infrared absorbing particles proceeds, allowing the infrared absorbing particles to be further micronized and dispersed. In other words, when performing dispersion treatment, grinding and dispersion treatment can be performed.

[0125] Although the content of infrared absorbing particles in the infrared absorbing particle dispersion described above is not particularly limited, it is preferable that the infrared absorbing particle dispersion of the present embodiment contains infrared particles in an amount of 0.001 mass% or more and 80.0 mass% or less. If the amount is 0.001 mass% or more, it can be suitably used for manufacturing a coating layer or a plastic molded article, which is a type of infrared absorbing particle dispersion containing infrared absorbing particles, and if the amount is 80.0 mass% or less, industrial production is easy. It is more preferable that the content of infrared absorbing particles in the infrared absorbing particle dispersion be 0.01 mass% or more and 80.0 mass% or less, and even more preferable that it be 1 mass% or more and 35 mass% or less.

[0126] In addition, when the visible light transmittance of the infrared absorbing particle dispersion is 80%, it is preferable that the concentration of infrared absorbing particles in the infrared absorbing particle dispersion be 0.05 mass% or more and 0.20 mass% or less.

[0127] When the visible light transmittance of the infrared absorbing particle dispersion is 80%, if the concentration of infrared absorbing particles in the infrared absorbing particle dispersion is 0.05 mass% or more and 0.20 mass% or less, it can have sufficient near-infrared absorption characteristics.

[0128] In the infrared absorbing particle dispersion of the present embodiment, the light transmittance of the liquid medium is denoted as the baseline, and the color tone when only light absorption by the infrared absorbing particles is calculated is L * a * b * b in the color system *It is desirable that it be >0. By satisfying the above range, it means that it is a light blue infrared absorbing particle.

[0129] The light transmittance of the infrared absorbing particle dispersion of the present embodiment can be measured as a function of wavelength by placing the infrared absorbing particle dispersion of the present embodiment in a suitable transparent container and using a spectrophotometer.

[0130] (3) Regarding the average dispersion particle size

[0131] The characteristics of the infrared absorbing particle dispersion of the present embodiment can be confirmed by measuring the dispersion state of the infrared absorbing particles when the infrared absorbing particles are dispersed in a liquid medium. For example, the state of the infrared absorbing particles within the dispersion can be confirmed by sampling the infrared absorbing particle dispersion of the present embodiment and measuring it with various commercially available particle size distribution meters. As a particle size distribution meter, for example, the measurement can be performed using the DLS-8000 manufactured by Otsuka Denshi Co., Ltd., which is based on the principle of dynamic light scattering.

[0132] The particle size of the infrared absorbing particles in the infrared absorbing particle dispersion of the present embodiment can be selected according to the purpose of use of the infrared absorbing dispersion, etc., and is not particularly limited.

[0133] In the infrared absorbing particle dispersion of the present embodiment, the average dispersed particle size of the infrared absorbing particles is preferably 1 nm or more and 800 nm or less, and more preferably 1 nm or more and 400 nm or less. This is because if the average dispersed particle size is 800 nm or less, strong infrared absorption ability can be exhibited by the infrared absorbing particles, and if the average dispersed particle size is 1 nm or more, industrial manufacturing is easy.

[0134] In particular, when the average dispersion particle size is 400 nm or less, it is possible to avoid the infrared shielding film or molded body (plate, sheet) becoming a gray color with monotonously reduced transmittance. In addition, by making the average dispersion particle size 400 nm or less, when the infrared absorbing particle dispersion liquid is used to form an infrared absorbing particle dispersion, the visible light transmittance can be increased by suppressing haze in particular.

[0135] When an infrared-absorbing particle dispersion, etc., is used for applications where light transparency in the visible light region is particularly required, it is desirable that the infrared-absorbing particles in said infrared-absorbing particle dispersion have an average dispersion particle size of 40 nm or less. Here, the average dispersion particle size is defined as the 50% volume cumulative particle size measured using the DLS-8000 manufactured by Otsuka Denshi Co., Ltd., which is based on the principle of dynamic light scattering. This is because if said infrared-absorbing particles have an average dispersion particle size smaller than 40 nm, light scattering caused by Mie scattering and Rayleigh scattering of the infrared-absorbing particles is sufficiently suppressed, thereby maintaining high light visibility in the visible light region while simultaneously maintaining transparency efficiently. When used for applications where transparency is particularly required, such as windproofing for automobiles, it is more desirable to make the average dispersion particle size of the infrared-absorbing particles 30 nm or less, and even more desirable to make it 25 nm or less, in order to further suppress scattering.

[0136] 4. Infrared absorbing particle dispersion

[0137] Next, the infrared absorbing particle dispersion of the present embodiment will be described.

[0138] The infrared absorbing particle dispersion of the present embodiment may include a solid medium and infrared absorbing particles already described disposed within the solid medium. Specifically, for example, as schematically illustrated in FIG. 2, the infrared absorbing particle dispersion (20) may have a solid medium (22) and infrared absorbing particles (21) already described, and the infrared absorbing particles (21) may be disposed within the solid medium (22). It is preferable that the infrared absorbing particles (21) be dispersed within the solid medium (22). Furthermore, FIG. 2 is a schematic drawing, and the infrared absorbing particle dispersion of the present embodiment is not limited to this form. For example, in FIG. 2, the infrared absorbing particles (21) are described as spherical particles, but the shape of the infrared absorbing particles (21) is not limited to this form and may have any shape. The infrared absorbing particles (21) may, for example, have a coating on their surface. The infrared absorbing particle dispersion (20) may include other additives as needed, in addition to the infrared absorbing particles (21) and the solid medium (22).

[0139] (1) Regarding the components contained

[0140] As described above, the infrared absorbing particle dispersion of the present embodiment may contain a solid medium and infrared absorbing particles as previously described. Since infrared absorbing particles have already been described, a description thereof is omitted. Below, the components that may contain the solid medium and the infrared absorbing particle dispersion as necessary are described.

[0141] (1-1) Solid media

[0142] First, I will explain solid media, which are solid-state media.

[0143] As for the solid medium, it is not particularly limited as long as it can be solidified while the infrared absorbing particles are dispersed. For example, inorganic binders obtained by hydrolyzing metal alkoxides or organic binders such as resins can be used.

[0144] In particular, it is preferable that the solid medium comprises a thermoplastic resin or a UV-curable resin. Furthermore, in the infrared absorbing particle dispersion of the present embodiment, if it becomes a solid ultimately even if it is in a liquid state during the manufacturing process, it can be referred to as a solid medium.

[0145] When the solid medium includes a thermoplastic resin, the thermoplastic resin is not particularly limited and can be arbitrarily selected according to the required transmittance or strength, etc. As the thermoplastic resin, for example, one type of resin selected from the group of resins consisting of polyethylene terephthalate resin, polycarbonate resin, acrylic resin, styrene resin, polyamide resin, polyethylene resin, vinyl chloride resin, olefin resin, epoxy resin, polyimide resin, fluoropolymer, ethylene-vinyl acetate copolymer, and polyvinyl acetal resin, a mixture of two or more types of resins selected from the said group of resins, or a copolymer of two or more types of resins selected from the said group of resins may be preferably used.

[0146] Meanwhile, when the solid medium contains a UV-curable resin, the UV-curable resin is not particularly limited, and, for example, an acrylic UV-curable resin can be suitably used.

[0147] (1-2) Regarding other components

[0148] As described below as a method for manufacturing an infrared absorbing particle dispersion, the infrared absorbing particle dispersion may contain a dispersant or a plasticizer, etc.

[0149] (2) Regarding the content of infrared absorbing particles

[0150] The content of infrared absorbing particles dispersed in the infrared absorbing particle dispersion is not particularly limited and can be arbitrarily selected depending on the application, etc. For example, the content of infrared absorbing particles in the infrared absorbing particle dispersion is preferably 0.001 mass% or more and 80.0 mass% or less, and more preferably 0.01 mass% or more and 70.0 mass% or less.

[0151] If the content of infrared absorbing particles in the infrared absorbing particle dispersion is 0.001 mass% or more, the thickness of the dispersion can be reduced to obtain the required infrared absorption effect. This is because it increases the range of applications and facilitates easy transport.

[0152] In addition, by keeping the content of infrared absorbing particles at 80.0 mass% or less, the content ratio of the solid medium in the infrared absorbing particle dispersion can be ensured, thereby increasing the strength.

[0153] It is preferable that the content of infrared absorbing particles per unit projected area included in the infrared absorbing particle dispersion be 0.04 g / m² or more and 10.0 g / m² or less. In addition, "content per unit projected area" refers to the weight (g) of infrared absorbing particles contained in the thickness direction per unit area (m²) through which light passes in the infrared absorbing particle dispersion of the present embodiment.

[0154] By setting the content of the infrared absorbing particle dispersion per unit projected area to the above range, the intensity of the infrared absorbing particle dispersion can be maintained while maintaining a high infrared absorption effect.

[0155] The color tone when only light absorption by infrared absorbing particles is calculated in the infrared absorbing particle dispersion of the present embodiment is L * a * b * b in the color system *It is preferable that it be >0. Satisfying the above range implies that it is a light blue infrared absorbing particle. Furthermore, the same applies to the infrared absorbing bonded transparent substrate or the infrared absorbing transparent substrate described later.

[0156] (3) Regarding the shape of the infrared absorbing particle dispersion

[0157] The infrared absorbing particle dispersion can be molded into any shape depending on the application, and the shape is not particularly limited.

[0158] The infrared absorbing particle dispersion can have, for example, a sheet shape, a board shape, or a film shape, and can be applied to various uses.

[0159] (4) Method for manufacturing infrared absorbing particle dispersion

[0160] Here, a method for manufacturing an infrared absorbing particle dispersion of the present embodiment is described.

[0161] An infrared absorbing particle dispersion may also be manufactured by, for example, mixing the aforementioned solid medium with the infrared absorbing particles already described, molding the mixture into a desired shape, and then curing it.

[0162] In addition, an infrared-absorbing particle dispersion may also be manufactured using, for example, the infrared-absorbing dispersion solution already described. In this case, the infrared-absorbing particle dispersion, plasticizer dispersion solution, or masterbatch described below may be prepared first, and then the infrared-absorbing particle dispersion may be manufactured using said infrared-absorbing particle dispersion, etc. This will be explained in detail below.

[0163] First, a mixing process can be carried out to mix the infrared absorbing particle dispersion described above with a thermoplastic resin or plasticizer. Subsequently, a drying process can be carried out to remove solvent components (liquid media components) derived from the infrared absorbing particle dispersion.

[0164] By removing the solvent component, an infrared absorbing particle dispersion (hereinafter simply referred to as "dispersion") in which infrared absorbing particles are dispersed at a high concentration in one or more materials selected from a thermoplastic resin and an infrared absorbing particle dispersion, or a dispersion in which infrared absorbing particles are dispersed at a high concentration in a plasticizer (hereinafter simply referred to as "plasticizer dispersion") can be obtained.

[0165] The method for removing solvent components from a mixture of an infrared absorbing particle dispersion and a thermoplastic resin, etc., is not particularly limited, but, for example, it is preferable to use a method of vacuum drying of the mixture of the infrared absorbing particle dispersion and the thermoplastic resin, etc. Specifically, the mixture of the infrared absorbing particle dispersion and the thermoplastic resin, etc., is vacuum dried while stirring to separate the dispersion or plasticizer dispersion from the solvent components. As for the apparatus used for vacuum drying, a vacuum stirring type dryer may be used, but any apparatus having the above function is acceptable and is not particularly limited. Furthermore, the pressure value during vacuum drying in the drying process is not particularly limited and can be selected arbitrarily.

[0166] By using a vacuum drying method to remove solvent components, the efficiency of solvent removal from a mixture of an infrared-absorbing particle dispersion and a thermoplastic resin can be improved. Furthermore, since the infrared-absorbing particle dispersion or the plasticizer dispersion is not exposed to high temperatures for extended periods when the vacuum drying method is used, it is desirable to prevent the aggregation of infrared-absorbing particles dispersed within the dispersion or the plasticizer dispersion. Additionally, the productivity of the infrared-absorbing particle dispersion or the plasticizer dispersion is increased, and the recovery of evaporated solvent is facilitated, which is also desirable from an environmental perspective.

[0167] In addition, as described above, a masterbatch may also be used when manufacturing an infrared absorbing particle dispersion.

[0168] A masterbatch can be manufactured, for example, by dispersing an infrared absorbing particle dispersion or an infrared absorbing particle dispersion in a resin and pelletizing the resin.

[0169] As another method for manufacturing a masterbatch, an infrared absorbing particle dispersion or an infrared absorbing particle dispersion is first uniformly mixed with a thermoplastic resin powder or pellet and, if necessary, other additives. Then, the mixture is kneaded in a vented single-screw or double-screw extruder and processed into a pellet shape by a method of cutting a conventional melt-extruded strand. In this case, the shape may be cylindrical or prismatic. It is also possible to employ the so-called hot-cut method, which involves directly cutting the melt-extruded material. In this case, it is common to take a shape close to a sphere.

[0170] By following the above steps, an infrared absorbing particle dispersion, a plasticizer dispersion, and a masterbatch can be prepared.

[0171] Furthermore, the infrared absorbing particle dispersion of the present embodiment can be manufactured by uniformly mixing an infrared absorbing particle dispersion, a plasticizer dispersion, or a masterbatch in a solid medium and molding it into a desired shape. At this time, as previously explained, an inorganic binder or an organic binder such as a resin may be used as the solid medium. As a binder, a thermoplastic resin or a UV-curable resin may be preferably used. Since thermoplastic resins and UV-curable resins that are particularly suitable for use have already been described, a description thereof is omitted here.

[0172] When using a thermoplastic resin as a solid medium, an infrared absorbing particle dispersion, a plasticizer dispersion or masterbatch, the thermoplastic resin, and additives other than plasticizers, depending on the purpose, can be first mixed. Then, the mixture can be manufactured into a sheet-shaped infrared absorbing particle dispersion formed, for example, into a flat or curved shape by various molding methods such as extrusion molding, injection molding, calender roll molding, extrusion, casting, or inflation molding.

[0173] In addition, when an infrared absorbing particle dispersion using a thermoplastic resin as a solid medium is used as an intermediate layer placed between, for example, a transparent substrate, and the thermoplastic resin contained in the infrared absorbing particle dispersion does not possess sufficient flexibility or adhesion to the transparent substrate, a plasticizer may be added when manufacturing the infrared absorbing particle dispersion. Specifically, for example, when the thermoplastic resin is polyvinyl acetal resin, it is preferable to add an additional plasticizer.

[0174] The plasticizer to be added is not particularly limited, and any substance capable of functioning as a plasticizer for the thermoplastic resin used can be used. For example, when polyvinyl acetal resin is used as the thermoplastic resin, plasticizers such as compounds of monohydric alcohols and organic acid esters, ester-based plasticizers such as polyhydric alcohol organic acid ester compounds, and phosphate-based plasticizers such as organic phosphate-based plasticizers can be preferably used.

[0175] The plasticizer is preferably an ester compound synthesized from a polyhydric alcohol and a fatty acid, in that it is desirable to be in a liquid state at room temperature.

[0176] And, as previously explained, the infrared absorbing particle dispersion of the present embodiment may have any shape, for example, a sheet shape, a board shape, or a film shape.

[0177] 5. Infrared absorption bonded transparent substrate

[0178] Next, an example of the configuration of the infrared absorption bonded transparent substrate of the present embodiment will be described.

[0179] The infrared absorption bonded transparent substrate of the present embodiment may have a plurality of transparent substrates and an infrared absorption particle dispersion of the present embodiment. Additionally, the infrared absorption particle dispersion may have a laminated structure disposed between the plurality of transparent substrates.

[0180] Specifically, as shown in FIG. 3, which is a schematic cross-sectional view along the stacking direction of a transparent substrate and an infrared absorbing particle dispersion, the infrared absorbing bonded transparent substrate (30) may have a plurality of transparent substrates (311, 312) and an infrared absorbing particle dispersion (32). The infrared absorbing particle dispersion (32) may be placed between the plurality of transparent substrates (311, 312). FIG. 3 shows an example having two transparent substrates (311, 312), but it is not limited to this form.

[0181] The infrared absorption bonded transparent substrate of the present embodiment may have a structure in which an infrared absorption particle dispersion, which is an intermediate layer, is fitted together using a transparent substrate (transparent substrate) on both sides.

[0182] As for the transparent substrate, it is not particularly limited and can be arbitrarily selected considering the visible light transmittance, etc. For example, as the transparent substrate, one or more types selected from plate glass, plate-shaped plastic, board-shaped plastic, film-shaped plastic, etc. may be used. In addition, it is preferable that the transparent substrate be transparent in the visible light region.

[0183] When using a transparent plastic substrate, the plastic material is not particularly limited and can be selected according to the application; polycarbonate resin, acrylic resin, polyethylene terephthalate resin, polyamide resin, vinyl chloride resin, olefin resin, epoxy resin, polyimide resin, fluoropolymer resin, etc., may be used.

[0184] In addition, two or more transparent substrates may be used in the infrared absorption bonded transparent substrate of the present embodiment, but when two or more transparent substrates are used, transparent substrates including different materials may be combined and used as the constituent transparent substrates, for example. In addition, the thickness of the constituent transparent substrates does not need to be the same, and transparent substrates with different thicknesses may be combined and used.

[0185] The infrared absorption bonded transparent substrate of the present embodiment may use the infrared absorption particle dispersion described previously as an intermediate layer. Since the infrared absorption particle dispersion has already been described, a description thereof is omitted here.

[0186] The infrared absorbing particle dispersion used in the infrared absorbing bonded transparent substrate of the present embodiment is not particularly limited, but it may preferably be formed into a sheet shape, a board shape, or a film shape.

[0187] In addition, the infrared absorption bonded transparent substrate of the present embodiment can be manufactured by bonding and integrating a plurality of opposing transparent substrates in which an infrared absorption particle dispersion formed into a sheet shape or the like is inserted.

[0188] In addition, when the infrared absorption bonded transparent substrate has three or more transparent substrates, there are two or more places between the transparent substrates, but it is not necessary to place an infrared absorption particle dispersion between all the transparent substrates, and it is sufficient to place an infrared absorption particle dispersion in at least one place.

[0189] 6. Infrared-absorbing transparent substrate

[0190] The infrared-absorbing transparent substrate of the present embodiment may have a transparent substrate and an infrared-absorbing layer disposed on at least one surface of the transparent substrate. The infrared-absorbing layer may be an infrared-absorbing particle dispersion as previously described. Specifically, as shown in FIG. 4, which is a schematic cross-sectional view along the lamination direction of the transparent substrate and the infrared-absorbing layer, the infrared-absorbing transparent substrate (40) may have a transparent substrate (41) and an infrared-absorbing layer (42). The infrared-absorbing layer (42) may be disposed on at least one surface (41A) of the transparent substrate (41).

[0191] The method for manufacturing an infrared-absorbing transparent substrate is not particularly limited. For example, using the infrared-absorbing particle dispersion described above, a coating layer containing infrared-absorbing particles can be formed on a transparent substrate (transparent substrate) selected from a film substrate and a glass substrate. By such operation, an infrared-absorbing film or infrared-absorbing glass, which is an infrared-absorbing transparent substrate, can be manufactured.

[0192] The coating layer can be produced, for example, by using a coating solution mixed with a plastic or monomer and an infrared absorbing particle dispersion solution already described.

[0193] For example, an infrared absorption film can be manufactured as follows.

[0194] A coating solution is obtained by adding a medium resin, which becomes a solid medium after curing, to the aforementioned infrared absorbing particle dispersion. After coating this coating solution onto the surface of a film substrate, the liquid medium contained in the coating solution is evaporated. Then, by curing the medium resin according to the method used for the medium resin, a coating layer (coating film) in which the infrared absorbing particles are dispersed within a solid medium is formed, thereby making it an infrared absorbing film.

[0195] In addition, by using a glass substrate as the transparent substrate, infrared absorbing glass can also be produced in the same way.

[0196] The medium resin of the coating layer above can be selected according to the purpose from, for example, UV-curable resin, thermosetting resin, electron beam-curable resin, room-temperature curable resin, thermoplastic resin, etc. Specifically, the medium resin may be, for example, polyethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin, ethylene vinyl acetate copolymer, polyester resin, polyethylene terephthalate resin, fluoropolymer, polycarbonate resin, acrylic resin, polyvinyl butyral resin, etc.

[0197] These media resins may be used alone or in combination. Above all, among the media resins for the coating layer, it is particularly desirable to use a UV-curable resin binder from the perspective of productivity and equipment costs.

[0198] In addition, binders using metal alkoxides can also be used. Representative examples of such metal alkoxides include alkoxides of Si, Ti, Al, and Zr. With binders using these metal alkoxides, it is possible for a solid medium to form a coating layer containing an oxide film by hydrolyzing and polycondensing through heating or the like.

[0199] As for the material of the film substrate described above, for example, polyester resin, acrylic resin, urethane resin, polycarbonate resin, polyethylene resin, ethylene vinyl acetate copolymer, vinyl chloride resin, fluoropolymer, etc., it can be used according to various purposes. Above all, as the film substrate of the infrared absorption film, it is preferable that it be a polyester film, and more preferable that it be a polyethylene terephthalate (PET) film. The term "film substrate" refers to a plastic substrate made of synthetic resin, and its thickness or shape is not limited.

[0200] In addition, to facilitate the adhesion of the coating layer to the film substrate, it is preferable that the surface of the film substrate undergoes surface treatment. Furthermore, to improve the adhesion of the coating layer to the glass substrate or film substrate, it is also a desirable configuration to form an intermediate layer on the glass substrate or film substrate and to form a coating layer on the intermediate layer. The composition of the intermediate layer is not particularly limited and can be composed of, for example, a polymer film, a metal layer, an inorganic layer (e.g., an inorganic oxide layer such as silica, titania, or zirconia), an organic / inorganic composite layer, etc.

[0201] A method of applying a coating solution containing an infrared absorbing particle dispersion, etc., to form a coating layer on a film substrate or a glass substrate is any method capable of uniformly applying the coating solution containing an infrared absorbing particle dispersion, etc. to the surface of said substrate, and is not particularly limited. Examples include bar coating, gravure coating, spray coating, dip coating, etc.

[0202] For example, in the case of a bar coating method using a UV-curable resin, an infrared-absorbing transparent substrate can be produced as follows.

[0203] A coating film can be formed on a film substrate or a glass substrate by using a coating solution in which additives are appropriately added and the liquid concentration is adjusted to have suitable leveling properties, and by using a wire bar of a number selected according to the thickness of the coating layer and the content of infrared absorbing particles. Then, a coating layer can be formed on a film substrate or a glass substrate by removing the liquid medium contained in the coating solution by drying and curing the solid medium by irradiating it with ultraviolet light. At this time, the drying conditions of the coating film vary depending on each component, the type of liquid medium, and the ratio of use, but are typically at a temperature of 60°C or higher and 140°C or lower for 20 seconds or more and 10 minutes or less. There are no particular restrictions on the irradiation with ultraviolet light, and, for example, a UV exposure device such as an ultra-high pressure mercury lamp can be suitably used.

[0204] In addition, in the preceding or subsequent processes for forming the coating layer, the adhesion between the transparent substrate and the coating layer, the smoothness of the film during coating, and the drying properties of the organic solvent may be adjusted. Examples of preceding processes include a surface treatment process of the transparent substrate and a pre-bake (pre-heating of the substrate) process, and examples of subsequent processes include a post-bake (post-heating of the substrate) process, which can be appropriately selected. In the pre-bake or post-bake process, it is preferable that the heating temperature be 80°C or higher and 200°C or lower, and the heating time be 30 seconds or higher and 240 seconds or lower.

[0205] The thickness of the coating layer on the film substrate or glass substrate is not particularly limited, but in practice, it is preferable to be 10 μm or less, and more preferable to be 6 μm or less. This is because if the thickness of the coating layer is 10 μm or less, it can provide sufficient pencil hardness and abrasion resistance, and in addition, prevent warping of the film substrate from occurring during volatilization of the liquid medium and curing of the solid medium in the coating layer.

[0206] The content of infrared absorbing particles in the coating layer is not particularly limited, but it is preferable that the content per projected area of ​​the coating layer be 0.1 g / m² or more and 10.0 g / m² or less. This is because if the content per projected area is 0.1 g / m² or more, the infrared absorbing particles can exhibit particularly high infrared absorption characteristics.

[0207] In addition, if the content per projected area is 10.0 g / m² or less, the transmittance of visible light of the infrared-absorbing transparent substrate can be sufficiently maintained.

[0208] In addition, to further impart ultraviolet absorption capabilities to the infrared absorption film or infrared absorption glass, which is an infrared absorption transparent substrate of the present embodiment, at least one of the following may be added as a coating layer: inorganic particles such as titanium oxide, zinc oxide, or cerium oxide, or organic particles such as benzophenone or benzotriazole.

[0209] 7. Regarding physical properties

[0210] Although infrared absorbing particle dispersions, infrared absorbing particle dispersions, infrared absorbing bonded transparent substrates, and infrared absorbing transparent substrates (collectively referred to as "infrared absorbing particle dispersions, etc."), the optical properties of infrared absorbing particle dispersions, etc. can be selected according to the application, etc., and are not particularly limited.

[0211] It is preferable that the light transmittance of an infrared absorbing particle dispersion, etc., at a wavelength of 850 nm be 30% or higher, and more preferable that it be 35% or higher. This is because by making the light transmittance at a wavelength of 850 nm 30% or higher, the transmittance of signals from mobile phones or various sensors can be increased.

[0212] It is desirable that the visible light transmittance of an infrared-absorbing particle dispersion, etc., be 70% or higher. This is because having a visible light transmittance of 70% or higher means excellent transparency to visible light, and thus sufficiently high visibility can be achieved even when used in the windows of passenger cars.

[0213] The solar transmittance of the infrared absorbing particle dispersion, etc., is preferably 65% ​​or less, and more preferably 60% or less. This is because by making the solar transmittance 65% or less, the intrusion of infrared rays into the indoor space can be sufficiently suppressed.

[0214] In addition, regarding the infrared absorbing particle dispersion, etc., from the perspective of effectively suppressing sunlight, it is desirable that the light transmittance at a wavelength of 1550 nm be 25% or less.

[0215] For infrared absorbing particle dispersions, etc., the haze value is preferably 2% or less, and more preferably 1% or less. By keeping the haze value at 2% or less, fogging is suppressed, and visibility can be improved when used on window glass, etc.

[0216] The infrared absorbing particles, infrared absorbing particle dispersion, infrared absorbing particle dispersion, infrared absorbing bonded transparent substrate, and infrared absorbing transparent substrate of the present embodiment can be used for various purposes, and their uses are not particularly limited. For example, they can be used in a wide range of fields requiring infrared absorption functions, such as window materials for vehicles, buildings, offices, and general houses, as well as single-pane glass, laminated glass, plastics, fibers, and other materials used in telephone booths, shop windows, lighting lamps, and transparent cases.

[0217] Examples

[0218] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples.

[0219] First, the method for evaluating samples in the following examples and comparative examples will be explained.

[0220] (1) Chemical analysis

[0221] Chemical analysis of the composite tungsten oxide particles containing the obtained infrared absorbing particles was performed by atomic absorption analysis (AAS) for Cs and by ICP emission spectroscopy (ICP-OES) for W. For oxygen, the sample was melted in He gas using a light element analysis device (LECO model: ON-836), and the CO gas produced by the reaction with carbon in the analysis crucible was quantified by IR absorption spectroscopy.

[0222] (2) Crystal structure, lattice constant

[0223] The crystal structure and lattice constant of the composite tungsten oxide particles containing infrared absorbing particles obtained in the following examples and comparative examples were measured and calculated.

[0224] First, the X-ray diffraction pattern of the infrared absorbing particles was measured using the powder X-ray diffraction method (θ-2θ method) with a powder X-ray diffraction apparatus (X'Pert-PRO / MPD manufactured by PANalytical, Spectris Co., Ltd.). From the obtained X-ray diffraction pattern, the crystal structure of the composite tungsten oxide particles contained in the particles was determined, and the lattice constants were calculated by Rietveld analysis. In addition, the external standard method was adopted for the Rietveld analysis. Rietveld analysis of the X-ray diffraction pattern of a Si standard powder (NIST640c) measured at the same time was performed first, and the zero shift value and half-width parameter obtained at that time were defined as the apparatus parameters, thereby refining the Rietveld analysis of the target composite tungsten oxide particles.

[0225] (3) Spectral transmittance of infrared-absorbing particle dispersion, color system

[0226] In the following examples and comparative examples, the transmittance of the infrared absorbing particle dispersion was measured by holding the dispersion in a spectrophotometer cell (manufactured by GL Science Co., Ltd., model number: S10-SQ-1, material: synthetic quartz, optical path length: 1 mm) and using a spectrophotometer U-4100 manufactured by Hitachi Seisakusho Co., Ltd.

[0227] During the measurement, the transmittance was measured with the liquid medium of the dispersion (methyl isobutyl ketone, etc., hereinafter abbreviated as MIBK) filled into the cell described above, thereby establishing a baseline for the transmittance measurement. As a result, the spectral transmittance and visible light transmittance described below exclude the contribution of light reflection from the surface of the spectrophotometer cell or light absorption by the liquid medium, and only the light absorption by infrared-absorbing particles is calculated.

[0228] Visible light transmittance and solar irradiance transmittance were calculated by measuring the transmitted light profile at intervals of 5 nm in the range of wavelengths from 200 nm to 2600 nm and based on JIS A 5759 (2016) in the range of wavelengths from 300 nm to 2100 nm.

[0229] And, the color system is L based on JIS Z 8701 (1999). * a * b * Using a color system (D65 light source / 10-degree field of view), L * , a * , b * Measured the value of.

[0230] (4) Infrared absorbing transparent substrate, spectral transmittance of infrared absorbing bonded transparent substrate, color system

[0231] The transmittance of the infrared-absorbing transparent substrate and the infrared-absorbing bonded transparent substrate was also measured using a spectrophotometer U-4100 manufactured by Hitachi Seisakusho Co., Ltd. In addition, solar irradiance transmittance and visible light transmittance were measured and calculated under the same conditions as in the evaluation before and after the heat resistance test below. For the infrared-absorbing bonded transparent substrate, the light transmittance at a wavelength of 850 nm was measured.

[0232] And, the color system is L based on JIS Z 8701 (1999). * a * b * Using a color system (D65 light source / 10-degree field of view), L * , a * , b * Measured the value of.

[0233] In addition, for the infrared-absorbing transparent substrate before and after the heat resistance test and the moisture resistance test described below, the transmitted light profile was measured at intervals of 5 nm in the wavelength range of 200 nm to 2600 nm, and the visible light transmittance and solar radiation transmittance were calculated in the wavelength range of 300 nm to 2100 nm based on JIS A 5759 (2016). For the heat resistance test and the moisture resistance test, for each test, a test specimen cut from the infrared-absorbing transparent substrate prepared in each example and comparative example was provided.

[0234] In addition, for the infrared-absorbing bonded transparent substrate, heat resistance and moisture resistance tests were conducted in the same manner, and the solar irradiance transmittance before and after the heat resistance and moisture resistance tests was calculated. For the infrared-absorbing bonded transparent substrate, samples for spectral transmittance, heat resistance, and moisture resistance tests were prepared separately for each example and comparative example, and each evaluation was performed.

[0235] (5) Heat resistance evaluation

[0236] An infrared-absorbing transparent substrate was maintained at 120°C in the atmosphere for 125 hours, and the changes in visible light transmittance and solar radiation transmittance before and after exposure to the atmosphere were evaluated. In the infrared-absorbing transparent substrate, a change in solar radiation transmittance before and after exposure of 1.0% or less was judged to have good heat resistance, and a change exceeding 1.0% was judged to have insufficient heat resistance.

[0237] Heat resistance evaluation was also performed on the infrared-absorbing bonded transparent substrate under the same conditions.

[0238] (6) Evaluation of moisture and heat resistance

[0239] An infrared-absorbing transparent substrate was maintained in an atmosphere of 85°C and 95% humidity for 94 hours, and the changes in visible light transmittance and solar radiation transmittance before and after exposure to the said atmosphere were evaluated. A change in solar radiation transmittance of less than 2.0% before and after exposure in the infrared-absorbing transparent substrate was judged to have good heat resistance, and a change of 2.0% or more was judged to have poor heat resistance.

[0240] Moisture and heat resistance was evaluated for infrared-absorbing bonded transparent substrates under the same conditions.

[0241] Below, the sample preparation conditions of the examples and comparative examples will be described.

[0242] [Example 1]

[0243] (1) Manufacturing of infrared absorbing particles

[0244] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed in a ratio equivalent to Cs / W (molar ratio) = 0.29 / 1.00, and then thoroughly mixed in a grinder to form a mixture (mixing process).

[0245] The mixture was subjected to reduction treatment for 1 hour at a temperature of 570°C under a supply of 3 volume% H2 gas with N2 gas as a carrier (second heat treatment process).

[0246] Next, the product was calcined at a temperature of 820°C for 0.5 hours under a 1 volume% compressed air supply using N2 gas as a carrier (first heat treatment process, first step), and also calcined at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0247] By the above operation, infrared absorbing particles (hereinafter abbreviated as “Powder A1”) containing hexagonal cesium tungsten bronze, i.e., cesium tungsten oxide particles were obtained.

[0248] As a result of the chemical analysis of powder A1, the Cs / W (molar ratio) was 0.29 / 1. The compositional ratios of other components are shown in the column of the chemical analysis compositional ratios in Table 1. In addition, the crystal structure and lattice constant of the cesium tungsten oxide particles, which are composite tungsten oxide particles, are shown in Table 1.

[0249] (2) Infrared absorbing particle dispersion

[0250] Powder A1 was weighed at 23.0 mass%, an acrylic polymer dispersant having a group containing an amine as a functional group (an acrylic dispersant with an amine value of 48 mgKOH / g and a decomposition temperature of 250°C) at 18.4 mass%, and MIBK, a liquid medium, at 58.6 mass%. These were loaded into a paint shaker containing 0.3 mm φ ZrO2 beads and subjected to grinding and dispersion treatment for 4 hours to obtain an infrared absorbing particle dispersion (hereinafter abbreviated as "dispersion B1").

[0251] The obtained dispersion B1 was appropriately diluted with MIBK to achieve a visible light transmittance of 80%, placed in a spectrophotometer cell, and the spectral transmittance was measured. Additionally, the concentration of infrared absorbing particles at this time is shown in Table 2 as the infrared absorbing particle concentration. The colorimeter was measured from the transmitted light profile when the dilution rate was adjusted to achieve a visible light transmittance of 80%. The results of the solar irradiance transmittance and the evaluation of the colorimeter are shown in Table 2.

[0252] (3) Infrared absorbing transparent substrate

[0253] Infrared absorbing glass and infrared absorbing film were fabricated and evaluated according to the following procedure. Infrared absorbing glass and infrared absorbing film are examples of infrared absorbing transparent substrates, and the coating layer, which is an infrared absorbing layer (infrared absorbing particle layer), is an infrared absorbing particle dispersion.

[0254] (3-1) Fabrication of Infrared Absorbing Glass

[0255] 100 mass% of the obtained dispersion B1 and 50 mass% of Aronix UV-3701 (hereinafter referred to as UV-3701), a UV-curable resin for hard coats, were mixed to form an infrared absorbing particle coating solution (hereinafter referred to as “coating solution C1”). Coating solution C1 was applied onto a 3 mm thick blue glass plate (Teijin HPE-50) using a bar coater (No. 16) to form a coating film. In addition, the same glass was used when manufacturing the infrared absorbing glass in other examples and comparative examples.

[0256] The glass coated with the coating film was dried at 70°C for 60 seconds to evaporate the solvent, which is a liquid medium, and then cured with a high-pressure mercury lamp. By doing so, an infrared absorbing glass was produced having a coating layer containing infrared absorbing particles on one surface of the glass substrate.

[0257] (3-2) Fabrication of Infrared Absorbing Film

[0258] In addition, coating solution C1 was applied onto a PET film substrate with a thickness of 50 μm using a bar coater (No. 8) to form a coating film. Also, in other examples and comparative examples, the same PET film was used when manufacturing the infrared absorption film.

[0259] A PET film having a coating film was dried at 70°C for 60 seconds to evaporate the solvent, which is a liquid medium, and then cured with a high-pressure mercury lamp. By doing so, an infrared absorbing film was produced having a coating layer containing infrared absorbing particles on one surface of a PET film substrate.

[0260] The optical properties of the obtained infrared-absorbing transparent substrate were evaluated. The evaluation results are shown in Table 3. In Table 3, when the type of substrate is glass, the evaluation results are for infrared-absorbing glass, and when the type of substrate is PET, the evaluation results are for infrared-absorbing film.

[0261] (3-3) Evaluation of heat resistance and moisture resistance

[0262] The heat resistance of the infrared absorbing glass and the moisture resistance of the infrared absorbing film according to Example 1 were evaluated.

[0263] (3-3-1) Heat resistance evaluation

[0264] The visible light transmittance and solar irradiance transmittance before and after exposure in the infrared absorbing glass according to Example 1 were evaluated.

[0265] The results of the evaluation are shown in Table 4.

[0266] (3-3-2) Evaluation of Moisture and Heat Resistance

[0267] The visible light transmittance and solar irradiance transmittance before and after exposure in the infrared absorption film according to Example 1 were evaluated.

[0268] The results of the evaluation are shown in Table 5.

[0269] (4) Infrared absorption bonded transparent substrate

[0270] In addition, dispersant a was further added to dispersion B1, which is an infrared absorbing particle dispersion according to Example 1, and the mass ratio of dispersant a to infrared absorbing particles was adjusted so that [dispersant a / infrared absorbing particles] = 3. Subsequently, methyl isobutyl ketone was removed from the adjusted dispersion using a spray dryer, and an infrared absorbing particle dispersion (hereinafter referred to as "dispersion") was obtained.

[0271] A composition for manufacturing an infrared absorption sheet was prepared by adding a predetermined amount of dispersion to a thermoplastic polycarbonate resin so that the visible light transmittance of the infrared absorption sheet (1.0 mm thickness) being manufactured becomes 80%.

[0272] The composition for manufacturing this infrared absorption sheet was kneaded at 280°C using a twin-screw extruder, extruded from a T-die, and formed into a sheet material with a thickness of 1.0 mm by the calender roll method to obtain the infrared absorption sheet according to Example 1. In addition, the infrared absorption sheet is an example of an infrared absorption particle dispersion.

[0273] The obtained infrared absorption sheet was placed between two green glass substrates with a thickness of 100 mm × 100 mm × about 2 mm, heated to 80°C to pre-bond, and then subjected to final bonding using an autoclave at 140°C and 14 kg / cm² to produce an infrared absorption bonded transparent substrate.

[0274] The optical properties, heat resistance, and moisture resistance of the obtained infrared absorption bonded transparent substrate were evaluated. The evaluation results are shown in Tables 6, 7, and 8.

[0275] [Example 2]

[0276] When preparing the infrared absorbing particle dispersion, the grinding and dispersion time was set to 10 hours. Except for the above points, the same operation as in Example 1 was performed to obtain powder A2, dispersion B2, infrared absorbing glass, and infrared absorbing bonded transparent substrate according to Example 2. The evaluation results are shown in Tables 1 to 3 and Table 6.

[0277] [Example 3]

[0278] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.27 / 1.00 (mixing process).

[0279] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0280] Next, it was heated under a 1 volume% compressed air supply using N2 gas as a carrier and calcined at a temperature of 820°C for 0.5 hours (first heat treatment process, first step).

[0281] In addition, it was calcined at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step). The grinding and dispersion time was set to 8 hours.

[0282] Based on the above, specifically, powder A3, dispersion B3, infrared absorbing glass, infrared absorbing film, and infrared absorbing bonded transparent substrate according to Example 3 were manufactured and evaluated by performing the same operations as in Example 1, except that the mixing process and heat treatment conditions when manufacturing the infrared absorbing particles and the grinding and dispersion time conditions when manufacturing the infrared absorbing particle dispersion were changed. The evaluation results are shown in Tables 1 to 8.

[0283] In Examples 4 to 15 and Comparative Examples 1 to 6 described below, some or all of the mixing process and heat treatment conditions when manufacturing infrared absorbing particles, and the grinding and dispersion time conditions when manufacturing infrared absorbing particle dispersion, are changed with respect to the points described below.

[0284] The X-ray diffraction pattern of the obtained powder A3 is shown in Fig. 5. As shown in Fig. 5, powder A3 is hexagonal Cs 0.3 (WO3)(ICDD01-081-1244) is identified as a single phase and is an infrared absorbing particle containing hexagonal tungsten cesium oxide particles.

[0285] [Example 4]

[0286] When manufacturing infrared absorbing particles, the mixture was heated under a 1 vol% compressed air supply with N2 gas as a carrier and calcined at a temperature of 820°C for 0.5 hours (first heat treatment process). Subsequently, it was heated under a 5 vol% H2 gas supply with N2 gas as a carrier and calcined at a temperature of 570°C for 1 hour (second heat treatment process, first step). In addition, it was calcined at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (second heat treatment process, second step).

[0287] In addition, when preparing the infrared absorbing particle dispersion, the grinding and dispersion time was set to 8 hours.

[0288] Except for the above points, the same operation as in Example 1 was performed to manufacture powder A4, dispersion B4, infrared absorbing glass, and infrared absorbing bonded transparent substrate according to Example 4, and an evaluation was performed.

[0289] In addition, powder A4 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0290] The evaluation results are shown in Tables 1 to 3 and Table 6.

[0291] [Example 5]

[0292] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.33 / 1.00 (mixing process).

[0293] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0294] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0295] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0296] Except for the above points, the same operation as in Example 1 was performed to manufacture powder A5, dispersion B5, and infrared absorption bonded transparent substrate according to Example 5, and an evaluation was conducted.

[0297] In addition, powder A5 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0298] The evaluation results are shown in Tables 1, 2, and 6.

[0299] [Example 6]

[0300] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.32 / 1.00 (mixing process).

[0301] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0302] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0303] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0304] Except for the above points, the same operation as in Example 1 was performed to manufacture powder A6, dispersion B6, and infrared absorption bonded transparent substrate according to Example 6, and an evaluation was conducted.

[0305] In addition, powder A6 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0306] The evaluation results are shown in Tables 1, 2, and 6.

[0307] [Example 7]

[0308] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.31 / 1.00 (mixing process).

[0309] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0310] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0311] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0312] Except for the above points, the same operation as in Example 1 was performed to manufacture powder A7, dispersion B7, and infrared absorption bonded transparent substrate according to Example 7, and to evaluate them.

[0313] In addition, powder A7 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0314] The evaluation results are shown in Tables 1, 2, and 6.

[0315] [Example 8]

[0316] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.30 / 1.00 (mixing process).

[0317] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0318] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0319] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0320] Except for the above points, the same operation as in Example 1 was performed to manufacture powder A8, dispersion B8, and infrared absorption bonded transparent substrate according to Example 8, and to evaluate them.

[0321] In addition, powder A8 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0322] The evaluation results are shown in Tables 1, 2, and 6.

[0323] [Example 9]

[0324] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.29 / 1.00 (mixing process).

[0325] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0326] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0327] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0328] Except for the above points, the same operation as in Example 1 was performed to manufacture powder A9, dispersion B9, and infrared absorption bonded transparent substrate according to Example 9, and to evaluate them. In addition, the mixing process was under the same conditions as in Example 1, but the substrate was added for verification.

[0329] In addition, powder A9 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0330] The evaluation results are shown in Tables 1, 2, and 6.

[0331] [Example 10]

[0332] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.28 / 1.00 (mixing process).

[0333] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0334] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0335] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0336] Except for the above points, the same operation as in Example 1 was performed to manufacture the powder A10, dispersion B10, and infrared absorption bonded transparent substrate according to Example 10, and to evaluate them.

[0337] In addition, powder A10 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0338] The evaluation results are shown in Tables 1, 2, and 6.

[0339] [Example 11]

[0340] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.26 / 1.00 (mixing process).

[0341] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0342] Next, the product was heated under a 1 volume% compressed air supply using N2 gas as a carrier and fired at a temperature of 820°C for 0.5 hours (first heat treatment process, first step), and also fired at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0343] When preparing an infrared absorption particle dispersion, the grinding and dispersion time was set to 5 hours.

[0344] Except for the above points, the same operation as in Example 1 was performed to manufacture the powder A11, dispersion B11, and infrared absorption bonded transparent substrate according to Example 11, and to evaluate them.

[0345] In addition, powder A11 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0346] The evaluation results are shown in Tables 1, 2, and 6.

[0347] [Example 12]

[0348] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.27 / 1 (mixing process).

[0349] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0350] Next, it was heated under a 1 volume% compressed air supply using N2 gas as a carrier and calcined at a temperature of 820°C for 1 hour (first heat treatment process, first step).

[0351] In addition, it was calcined at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0352] When preparing an infrared absorbing particle dispersion, the grinding and dispersion time was set to 8 hours.

[0353] Except for the above points, the same operation as in Example 1 was performed to prepare powder A12 and dispersion B12 according to Example 12, and an evaluation was conducted.

[0354] In addition, powder A12 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0355] The evaluation results are shown in Table 1 and Table 2.

[0356] [Example 13]

[0357] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.27 / 1 (mixing process).

[0358] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0359] Next, it was heated under a 1 volume% compressed air supply using N2 gas as a carrier and calcined at a temperature of 820°C for 1.5 hours (first heat treatment process, first step).

[0360] In addition, it was calcined at a temperature of 820°C for 0.5 hours under an N2 gas atmosphere (first heat treatment process, second step).

[0361] When preparing an infrared absorbing particle dispersion, the grinding and dispersion time was set to 8 hours.

[0362] Except for the above points, the same operation as in Example 1 was performed to prepare powder A13 and dispersion B13 according to Example 13, and an evaluation was conducted.

[0363] In addition, powder A13 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0364] The evaluation results are shown in Table 1 and Table 2.

[0365] [Example 14]

[0366] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.27 / 1 (mixing process).

[0367] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0368] Next, it was heated under a 1 volume% compressed air supply using N2 gas as a carrier and calcined at a temperature of 820°C for 45 minutes (first heat treatment process, first step).

[0369] In addition, it was calcined at a temperature of 820°C for 15 minutes under an N2 gas atmosphere (first heat treatment process, second step).

[0370] When preparing an infrared absorbing particle dispersion, the grinding and dispersion time was set to 8 hours.

[0371] Except for the above points, the same operation as in Example 1 was performed to prepare powder A14 and dispersion B14 according to Example 14, and an evaluation was conducted.

[0372] In addition, powder A14 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0373] The evaluation results are shown in Table 1 and Table 2.

[0374] [Example 15]

[0375] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.27 / 1 (mixing process).

[0376] The mixture was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour (second heat treatment process).

[0377] Next, it was heated under a 1 volume% compressed air supply using N2 gas as a carrier and calcined at a temperature of 820°C for 2 hours (first heat treatment process, first step).

[0378] When preparing an infrared absorbing particle dispersion, the grinding and dispersion time was set to 8 hours.

[0379] Except for the above points, the same operation as in Example 1 was performed to prepare powder A15 and dispersion B15 according to Example 15, and an evaluation was conducted.

[0380] In addition, powder A15 is an infrared absorbing particle containing particles of complex tungsten oxide having a hexagonal crystal structure as shown in Table 1.

[0381] The evaluation results are shown in Table 1 and Table 2.

[0382] [Example 16]

[0383] Using dispersion B3 according to Example 3, a composition was prepared comprising 0.15 mass% of cesium tungsten oxide particles, which are infrared absorbing particles, 73.0 mass% of polyvinyl butyral resin (PVB), and 26.85 mass% of triethylene glycol di-2-ethylhexanoate (3GO), which is a plasticizer. Then, the composition was kneaded in a twin-screw extruder, extruded from a T-die, and formed into a sheet material with a thickness of 0.16 mm by the calender roll method to obtain an infrared absorbing sheet according to Example 16.

[0384] An infrared absorption bonded transparent substrate according to Example 16 was obtained in the same manner as Example 1, except that the obtained infrared absorption sheet was sandwiched between two glass substrates with a thickness of 100 mm × 100 mm × 3 mm.

[0385] The evaluation results of the obtained infrared absorption bonded transparent substrate are shown in Table 9.

[0386] [Comparative Example 1]

[0387] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.33 / 1.00 (mixing process).

[0388] The mixture obtained from the mixing process was heated under a 5 volume% H2 gas supply with N2 gas as a carrier and subjected to reduction treatment at a temperature of 570°C for 1 hour.

[0389] Next, it was calcined at a temperature of 820°C for 1 hour under an N2 gas atmosphere. In addition, the process corresponding to the first step of the first heat treatment process in Example 1 was not performed.

[0390] When preparing an infrared absorbing particle dispersion, the grinding and dispersion time was set to 10 hours.

[0391] Except for the above points, the same operation as in Example 1 was performed to obtain powder A21, dispersion B21, infrared absorbing glass, infrared absorbing film, and infrared absorbing bonded transparent substrate according to Comparative Example 1. In addition, XRD pattern measurements were performed on the obtained powder A21. The evaluation results are shown in FIG. 6 and Tables 1 to 8.

[0392] [Comparative Example 2]

[0393] When manufacturing infrared absorbing particles, the mixture was heated under a 1 volume% compressed air supply with N2 gas as a carrier and calcined at a temperature of 820°C for 0.5 hours. In addition, the process corresponding to the second heat treatment process and the second step of the first heat treatment process in Example 1 was not performed.

[0394] When preparing an infrared absorbing particle dispersion, the grinding and dispersion time was set to 8 hours.

[0395] Except for the above points, the same operation as in Example 1 was performed to obtain powder A22, dispersion B22, and infrared absorbing glass according to Comparative Example 2. In addition, the XRD pattern of the obtained powder A22 was measured. The results of the evaluation are shown in FIG. 6 and Tables 1 to 3.

[0396] [Comparative Example 3]

[0397] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.27 / 1.00. Except for the above, the same operation as in Comparative Example 1 was performed to obtain powder A23 and dispersion B23 of Comparative Example 3. The evaluation results are shown in Tables 1 and 2.

[0398] [Comparative Example 4]

[0399] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.26 / 1.00. Except for the above, the same operation as in Comparative Example 1 was performed to obtain powder A24 and dispersion B24 of Comparative Example 4. The evaluation results are shown in Tables 1 and 2.

[0400] [Comparative Example 5]

[0401] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.25 / 1.00. Except for the above, the same operation as in Comparative Example 1 was performed to obtain powder A25 and dispersion B25 according to Comparative Example 5. The evaluation results are shown in Tables 1 and 2.

[0402] [Comparative Example 6]

[0403] Each powder of tungstic acid (H2WO4) and cesium carbonate (Cs2CO3) was weighed and mixed in a ratio equivalent to Cs / W (molar ratio) = 0.20 / 1.00. Except for the above, the same operation as in Comparative Example 1 was performed to obtain powder A26 and dispersion B26 according to Comparative Example 6. The evaluation results are shown in Tables 1 and 2.

[0404] [Comparative Example 7]

[0405] An infrared absorption bonded transparent substrate according to Comparative Example 7 was obtained in the same manner as in Example 16, except that dispersion B21 according to Comparative Example 1 was used.

[0406] The evaluation results of the obtained infrared absorption bonded transparent substrate are shown in Table 9.

[0407] [Reference Example 1]

[0408] Instead of powder A1, tin-doped indium oxide powder from NYACOL was used to make powder A30.

[0409] In addition, dispersion B30 according to Reference Example 1 was obtained in the same manner as in Example 1, except that such powder A30 was used. The evaluation results are shown in Tables 1 and 2.

[0410]

[0411]

[0412]

[0413]

[0414]

[0415]

[0416]

[0417]

[0418]

[0419] [organize]

[0420] As is evident from each evaluation result, it was confirmed that the infrared absorbing particles according to Examples 1 to 15 have a hexagonal crystal structure and are particles of composite tungsten oxide having a predetermined composition.

[0421] In addition, when the standard for visible light transmittance in the infrared absorbing particle dispersion was set to 80%, the concentration of infrared absorbing particles was 0.05 mass% or more and 0.20 mass% or less. Furthermore, the infrared absorbing particle dispersions of Examples 1 to 15 were b *At the point where α is greater than 0, it was confirmed that the infrared absorbing particles contained in the infrared absorbing particle dispersion were light blue. In addition, it was confirmed that the infrared absorbing bonded transparent substrates of Examples 1 to 3 and 16 had a light transmittance of 30% or higher at 850 nm, which was also higher than that of Comparative Example 1 and Comparative Example 7. In other words, it was confirmed that the signal transmittance of mobile phones and various sensors is high, thereby increasing the detection precision of various sensors.

[0422] Regarding the infrared-absorbing transparent substrate for which a color system evaluation was performed, L * a * b * b in the color system * It was confirmed that >0. In addition, the infrared-absorbing transparent substrates of Example 1 and Example 3, which evaluated weather resistance, showed heat resistance of Δ solar transmittance 1.0% or less and moisture resistance of Δ solar transmittance less than 2.0%, and it was confirmed that they had superior weather resistance compared to the infrared-absorbing transparent substrate of Comparative Example 1.

[0423] In addition, the infrared-absorbing transparent substrate of another embodiment, for which evaluation results are not shown, exhibits the same trend regarding weather resistance evaluation.

[0424] That is, in Examples 1 to 15, it was confirmed that infrared absorbing particles with light blue color and excellent weather resistance and infrared absorption characteristics could be obtained.

[0425] Meanwhile, although the infrared absorbing particles according to Comparative Examples 1, 3 to 6 had a hexagonal crystal structure, the color tone when only the light absorption by the infrared absorbing particles in the infrared absorbing particle dispersion was calculated was L * a * b * b in the color system *It was <0. In addition, the infrared absorbing particles in Comparative Example 2 are a mixture of materials having a crystal structure other than hexagonal, and as is clear from the evaluation results of the infrared absorbing particle dispersion shown in Table 2, the solar transmittance is high, so it can be said that the infrared absorption characteristics are poor.

[0426] This application claims priority based on Patent Application No. 2021-060997 filed with the Japan Patent Office on March 31, 2021 and Patent Application No. 2021-140530 filed with the Japan Patent Office on August 30, 2021, and incorporates the entire contents of Patent Application No. 2021-060997 and Patent Application No. 2021-140530 into this international application. Explanation of the symbols

[0427] 10: Infrared absorbing particle dispersion 11, 21: Infrared absorbing particles 12: Liquid media 20, 32: Infrared absorbing particle dispersion 22: Solid Media 30: Infrared absorption bonded transparent substrate 311, 312, 41: Transparent markings 40: Infrared-absorbing transparent substrate 41A: One side 42: Infrared absorption layer

Claims

Claim 1 As an infrared absorbing particle containing composite tungsten oxide particles, said composite tungsten oxide particles have a hexagonal crystal structure and general formula M x W y O z (wherein M is one or more elements selected from Cs, Rb, K, Tl, Ba, Ca, Sr, Fe, W is tungsten, O is oxygen, 0.25≤x / y≤0.39, 2.70≤z / y≤2.90) is a particle of composite tungsten oxide, and the surface of the composite tungsten oxide particle is polaron absorption free, an infrared absorbing particle. Claim 2 In the first paragraph, an infrared absorbing particle, wherein the surface is coated with a compound containing one or more atoms selected from Si, Ti, Zr, and Al. Claim 3 An infrared absorbing particle dispersion containing a liquid medium and an infrared absorbing particle described in claim 1 or 2 disposed in the liquid medium. Claim 4 In paragraph 3, an infrared absorbing particle dispersion having an average dispersed particle diameter of the infrared absorbing particles of 1 nm or more and 800 nm or less. Claim 5 In paragraph 3, the infrared absorbing particle dispersion, wherein the liquid medium is one type selected from a group of liquid medium materials including water, organic solvent, oil, liquid resin, and liquid plasticizer for plastics, or a mixture of two or more types selected from the group of liquid medium materials. Claim 6 In paragraph 3, the infrared absorbing particle dispersion comprises a dispersant. Claim 7 In paragraph 3, an infrared absorbing particle dispersion containing 0.001 mass% or more and 80.0 mass% or less of the infrared absorbing particles. Claim 8 In paragraph 3, when the visible light transmittance of the infrared absorbing particle dispersion is 80%, the color tone when only the light absorption by the infrared absorbing particles is calculated is L * a * b * b in the color system * >0, infrared absorbing particle dispersion. Claim 9 In paragraph 3, an infrared absorbing particle dispersion having a concentration of 0.05 mass% or more and 0.20 mass% or less when the visible light transmittance is 80%. Claim 10 An infrared absorbing particle dispersion having a solid medium and infrared absorbing particles described in claim 1 or 2 disposed in the solid medium. Claim 11 In claim 10, when the content of infrared absorbing particles per unit projected area included in the infrared absorbing particle dispersion is 0.04 g / m² or more and 10.0 g / m² or less, the color tone when only light absorption by said infrared absorbing particles is calculated is L * a * b * b in the color system * >0 infrared absorbing particle dispersion. Claim 12 In claim 10, the above solid medium is an infrared absorbing particle dispersion comprising a thermoplastic resin or a UV-curable resin. Claim 13 In claim 12, the above-mentioned thermoplastic resin is an infrared absorbing particle dispersion in which one type of resin is selected from the group of resins consisting of polyethylene terephthalate resin, polycarbonate resin, acrylic resin, styrene resin, polyamide resin, polyethylene resin, vinyl chloride resin, olefin resin, epoxy resin, polyimide resin, fluoropolymer, ethylene-vinyl acetate copolymer, and polyvinyl acetal resin, a mixture of two or more types of resins selected from the said group of resins, or a copolymer of two or more types of resins selected from the said group of resins. Claim 14 In paragraph 10, an infrared absorbing particle dispersion having a sheet shape, a board shape, or a film shape. Claim 15 An infrared absorption bonded transparent substrate having a plurality of transparent substrates and an infrared absorption particle dispersion described in claim 10, wherein the infrared absorption particle dispersion has a laminated structure disposed between the plurality of transparent substrates. Claim 16 In claim 15, an infrared absorption bonded transparent substrate having a light transmittance of 30% or more at a wavelength of 850 nm. Claim 17 An infrared absorbing transparent substrate having a transparent substrate and an infrared absorbing layer disposed on at least one surface of the transparent substrate, wherein the infrared absorbing layer is an infrared absorbing particle dispersion described in claim 10. Claim 18 In claim 17, an infrared-absorbing transparent substrate having a light transmittance of 30% or more at a wavelength of 850 nm.

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