Infrared-transmitting material particles, infrared-transmitting material particle dispersions, infrared-transmitting material particle dispersions, and infrared-transmitting laminates

Abstract

The present invention provides novel infrared-transmitting material particles that can block visible light while transmitting infrared light. [Solution] Composition formula: A x Bi y O z It contains a complex bismuth oxide represented by, In the above compositional formula, element A is one or more elements selected from calcium, strontium, and barium, Bi is bismuth, and O is oxygen. The above compositional formula comprises infrared-transmitting material particles where x, y, and z satisfy the relationships 2.5 ≤ z / y ≤ 4.0 and 0.6 ≤ x / y ≤ 1.8.

Description

[Technical Field]

[0001] The present invention relates to infrared-transmitting material particles, infrared-transmitting material particle dispersions, infrared-transmitting material particle dispersions, and infrared-transmitting laminates. [Background technology]

[0002] In recent years, infrared sensors and infrared cameras have been utilized in a wide range of technological fields.

[0003] For example, in the automotive sector, infrared sensors and infrared cameras are installed on vehicles to detect the surrounding environment for the purpose of autonomous driving and driver assistance, and sensing using infrared light in the wavelength range of approximately 800nm ​​to 1100nm is now being performed.

[0004] To accurately detect the conditions around a vehicle, high-precision infrared sensors and infrared cameras (hereinafter, infrared sensors and infrared cameras will be collectively referred to as "infrared sensors, etc.") are required.

[0005] In infrared sensors and the like, light in the visible to near-infrared range becomes noise, causing a decrease in measurement accuracy. Therefore, there is a need for filters or coatings that can selectively transmit light in the target infrared range from the light input to the detection unit, while reducing the transmittance of light in the visible to near-infrared range, and infrared-transmitting materials have been studied for a long time.

[0006] For example, Patent Document 1 discloses an infrared-transmitting product having a coating layer that transmits infrared rays, and also discloses that aggregates of fine particles of pigments such as titanium dioxide and zinc oxide are dispersed in the coating layer.

[0007] Patent Document 2 describes an infrared-transmitting, curable composition containing anthraquinone-based, perinone-based, and quinophthalone-based dyes. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2021-56346 [Patent Document 2] International Publication No. 2021 / 084980 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] By the way, depending on the type and application of an infrared sensor or the like, the properties required for an infrared transmitting material may also differ. For this reason, a novel infrared transmitting material has been demanded so that an optimal selection can be made according to the application or the like.

[0010] In one aspect of the present invention, an object is to provide novel infrared transmitting material particles that can block visible light and transmit infrared rays. [Means for Solving the Problems]

[0011] The infrared transmitting material particles according to one embodiment of the present invention have a composition formula: A x Bi y O z and contain a composite bismuth oxide represented by In the composition formula, element A is one or more elements selected from calcium, strontium, and barium, Bi is bismuth, O is oxygen, x, y, and z in the composition formula satisfy the relational expressions of 2.5 ≤ z / y ≤ 4.0 and 0.6 ≤ x / y ≤ 1.8. [Effects of the Invention]

[0012] According to one embodiment of the present invention, novel infrared transmitting material particles that can block visible light and transmit infrared rays can be provided. [Brief Description of the Drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram of an infrared transmitting material particle dispersion liquid according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is an explanatory view of an infrared transmitting material particle dispersion according to one aspect of the present disclosure. [Figure 3] FIG. 3 is an explanatory view of an infrared transmitting laminate according to one aspect of the present disclosure. [Figure 4] FIG. 4 is an explanatory view of an infrared transmitting substrate according to one aspect of the present disclosure. [Figure 5] FIG. 5 is a transmittance curve of resin sheets produced in Examples and Comparative Examples.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention.

[0015] Hereinafter, [1] infrared transmitting material particles, [2] method for producing infrared transmitting material particles, [3] infrared transmitting material particle dispersion, and [4] infrared transmitting material particle dispersion will be described in detail in this order. [1] Infrared Transmitting Material Particles The inventors of the present invention have studied novel infrared transmitting material particles.

[0016] As a result, it has been found that by using infrared transmitting material particles containing a composite bismuth oxide (hereinafter also referred to as "composite oxide"), visible light can be blocked and infrared rays can be transmitted, and the present invention has been completed. The infrared transmitting material particles of the present embodiment are preferably near infrared transmitting material particles that block visible light while transmitting light in the near infrared region, particularly in the infrared region.

[0017] In studying new infrared-transmitting material particles, the inventor of the present invention focused on the oxide of bismuth (Bi), which is one of the typical elements. However, bismuth trioxide (Bi2O3), the most typical oxide of bismuth, is a semiconductor with a predicted band gap of about 2.9 eV. Although it has a pale yellow color, it did not have sufficient ability to shield visible light. However, when a composite bismuth oxide with a positive element added to the above oxide was prepared, it was found that the electronic band structure changed greatly and absorption occurred in the visible light region. Moreover, surprisingly, the composite bismuth oxide focused on by the inventor of the present invention can maintain a high transmittance of light in the near-infrared region even when it sufficiently absorbs light in the visible light region and reduces the transmittance of light in the visible light region, and it has been found that it functions as infrared-transmitting material particles.

[0018] The principle by which the composite bismuth oxide selectively absorbs light in the visible light region while maintaining a high transmittance of light in the infrared region is still under research. However, the inventors of the present invention believe that these absorption characteristics are fundamentally due to the coexistence of trivalent bismuth (Bi 3+ ) and pentavalent bismuth (Bi 5+ ) in the composite bismuth oxide.

[0019] For example, in BaBiO3 having a monoclinic structure, which is one of the composite bismuth oxides, the barium (Ba) constituting the crystal has a valence of 2 (Ba 2+ ), and oxygen has a valence of -2 (O 2- ). And bismuth can take two kinds of valences, trivalent (Bi 3+ ) and pentavalent (Bi 5+ ), depending on the site where it exists.

[0020] At this time, trivalent bismuth and pentavalent bismuth have different energy levels, and interband transitions can occur between their respective energy levels. Since the energy of this interband transition corresponds to the energy of light with wavelengths of visible light (wavelengths from 380 nm to 780 nm), it is thought that selective absorption of light in the visible light region occurs. On the other hand, since interband transitions hardly occur in the energy band lower than the energy in question, i.e., in light with longer wavelengths, the inventors of this invention speculate that high transparency is ensured for infrared light with wavelengths longer than visible light. Other composite bismuth oxides besides BaBiO3 also have trivalent (Bi) in their crystal structure. 3+ ) and pentavalent (Bi 5+ It is thought that selective absorption of light in the visible light region occurs through the same mechanism in order for these two factors to coexist.

[0021] Furthermore, the inventors of the present invention have found that within a specific portion of the composition range of the composite bismuth oxide, there is a range that is particularly effective as infrared-transmitting material particles. Specifically, they have found that by setting the composition range of the composite bismuth oxide within a predetermined range, it is possible to maintain high transmittance in the infrared region while exhibiting particularly strong absorption in the visible light region. (1) About the composition The infrared-transmitting material particles of this embodiment have the composition formula: A x Bi y O z It may contain a composite bismuth oxide represented by the above composition formula. The infrared-transmitting material particles of this embodiment may consist solely of the composite bismuth oxide represented by the above composition formula. However, this does not exclude the inclusion of unavoidable impurities introduced during the manufacturing process.

[0022] In the above chemical formula, element A(A) is one or more elements selected from Ca (calcium), Sr (strontium), and Ba (barium). Note that element A may contain multiple elements, such as barium and strontium. In the above chemical formula, Bi represents bismuth and O represents oxygen.

[0023] In the above empirical formula, x, y, and z are coefficients. Preferably, x, y, and z in the above empirical formula satisfy the relationships 2.5 ≤ z / y ≤ 4.0 and 0.6 ≤ x / y ≤ 1.8, and more preferably, 2.9 ≤ z / y ≤ 3.1 and 0.9 ≤ x / y ≤ 1.1. This is because satisfying these relationships allows Bi to be formed. 3+ and Bi 5+ This is because the relative abundance of the element is appropriately adjusted, resulting in stronger selective absorption in the visible light region. (2) Regarding volume-average particle size The volume-average particle diameter of the infrared-transmitting material particles in this embodiment is not particularly limited, but is preferably 1 nm to 800 nm, more preferably 1 nm to 200 nm, even more preferably 1 nm to 100 nm, and particularly preferably 1 nm to 80 nm.

[0024] By setting the volume-average particle diameter of the infrared-transmitting material particles in this embodiment to 800 nm or less, the haze for infrared light can be reduced in the infrared-transmitting material dispersion containing the infrared-transmitting material particles of this embodiment. Therefore, the measurement accuracy when the infrared-transmitting material dispersion is used in an infrared sensor or the like can be particularly improved.

[0025] Furthermore, by setting the volume-average particle diameter of the infrared-transmitting material particles in this embodiment to 1 nm or more, it is possible to manufacture them industrially with high productivity and stability.

[0026] The method for measuring the volume-average particle size will be explained in the examples. (3) Regarding the crystal structure The crystal structure of the composite bismuth oxide is not particularly limited, but it can have one or more crystal structures selected from, for example, cubic, tetragonal, orthorhombic, and monoclinic. The infrared-transmitting material particles of this embodiment may contain composite bismuth oxides with different crystal structures, or they may consist only of composite bismuth oxides with the same crystal structure. [2] Method for manufacturing infrared-transmitting material particles Next, a method for producing the infrared-transmitting material particles of this embodiment will be described.

[0027] The infrared-transmitting material particles of this embodiment can be manufactured, for example, using a solid-phase reaction method.

[0028] When synthesizing the infrared-transmitting material particles of this embodiment using a solid-phase reaction method, for example, an element A source containing element A and a bismuth element source containing bismuth can be used as raw materials.

[0029] The method for producing infrared-transmitting material particles of this embodiment may include a mixed powder preparation step (first mixed powder preparation step) for preparing a mixed powder of an element A source and a bismuth element source.

[0030] As the source of element A, one or more selected from element A compounds and element A itself can be used. Preferably, the element A compound used as a raw material is one or more selected from oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, organic compounds, sulfides, and chlorides of element A.

[0031] Since element A has already been explained, we will omit the explanation here.

[0032] As the bismuth element source, one or more selected from bismuth compounds and elemental bismuth can be used. Preferably, the bismuth compound used as a raw material is one or more selected from bismuth oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, organic compounds, sulfides, and chlorides.

[0033] In the mixed powder preparation process, the specific procedure for obtaining a mixed powder of an element A source and a bismuth element source is not particularly limited. For example, one method is to dry-mix an element A compound, which is the element A source, and a bismuth compound, which is the bismuth element source, in powder form to obtain a mixed powder. Alternatively, the element A compound, which is the element A source, can be dissolved in water, wet-mixed with a bismuth compound, which is the bismuth element source, and then dried to obtain a mixed powder.

[0034] In the mixed powder preparation process, it is preferable to mix the elements such that the ratio of element A to bismuth in the resulting mixed powder is equal to the ratio of element A to bismuth in the target composite bismuth oxide.

[0035] In other words, it is preferable to mix the raw materials so as to satisfy the aforementioned molar ratio x / y of element A to element bismuth in the target composite oxide. It is preferable that x and y satisfy the relationship 0.6 ≤ x / y ≤ 1.8, and more preferably 0.9 ≤ x / y ≤ 1.1, as described above. For this reason, it is preferable to mix the element A source and the bismuth source so as to satisfy the above preferred range.

[0036] Furthermore, the infrared-transmitting material particles of this embodiment can also be synthesized in multiple steps to obtain infrared-transmitting material particles containing a composite oxide of the desired composition. In this case, in the first mixed powder preparation step, the element A source and the bismuth element source can be mixed to obtain the composition of the intermediate product.

[0037] Furthermore, the method for producing infrared-transmitting material particles of this embodiment may include a firing step (first firing step) in which the mixed powder obtained in the mixed powder preparation step (first mixed powder preparation step) is fired.

[0038] The conditions for the firing process are not particularly limited. In the firing process, for example, the mixed powder can be fired in any of the following atmospheres selected from an inert gas-only atmosphere, a reducing gas-only atmosphere, a vacuum atmosphere, a mixed gas atmosphere of an inert gas and a reducing gas, or an oxidizing atmosphere containing oxygen.

[0039] For example, when introducing an oxygen vacancy in a composite oxide to make the z / y ratio in the aforementioned compositional formula smaller than the stoichiometric ratio, the calcination atmosphere is preferably a mixed gas atmosphere of an inert gas and a reducing gas. The reducing gas is not particularly limited, but hydrogen gas is preferred, for example. When hydrogen gas is used as the reducing gas, the volume ratio of hydrogen gas is preferably 1% or more, and more preferably 3% or more. There is no particular upper limit to the volume ratio of hydrogen gas, and it can also be reduced gas alone, so it can be up to 100%.

[0040] The inert gas is not particularly limited, but one or more gases selected from nitrogen gas, noble gases, etc., can be used.

[0041] As an oxidizing atmosphere, any atmosphere containing oxygen is acceptable; for example, an atmosphere containing 18% to 100% oxygen by volume can be used. For example, an atmospheric atmosphere can be used.

[0042] The firing temperature conditions in the firing process are not particularly limited, but it is preferable that the firing temperature be above the temperature at which the generated composite oxide begins to crystallize, and below the melting point of the composite oxide. Specifically, for example, it is preferable that the firing temperature be between 400°C and 1000°C.

[0043] The infrared-transmitting material particles of this embodiment can be synthesized in multiple steps to obtain infrared-transmitting material particles containing a composite oxide of the desired composition.

[0044] When synthesis is carried out in multiple stages, for example, an element source that matches the desired composition, such as a bismuth element source, can be added and mixed to the intermediate product obtained in the calcination step (first calcination step) (second mixed powder preparation step). It is also possible to prepare multiple types of intermediate products with different compositions and mix them in the second mixed powder preparation step. When preparing multiple types of intermediate products with different compositions, the mixed powder preparation step (first mixed powder preparation step) and calcination step (first calcination step) described above can be performed for each intermediate product.

[0045] The bismuth element source used in the second mixed powder preparation step is not particularly limited, but for example, the bismuth element source material described in the first mixed powder preparation step can be used. In the second mixed powder preparation step, it is preferable to mix the powder so that the ratio of the amount of substance of element A to the amount of substance of bismuth element in the resulting mixed powder is the same as the ratio of the amount of substance of element A to the amount of substance of bismuth element in the target composite oxide. That is, it is preferable to mix the powder so that it satisfies the range x / y, which is the ratio of the amount of substance of element A to the amount of substance of bismuth element in the target composite oxide. Mixing can be carried out in the same manner as in the mixed powder preparation step, so the explanation is omitted here.

[0046] The resulting mixed powder can then be subjected to a firing process (second firing process) to prepare the infrared-transmitting material particles of this embodiment. The conditions for the second firing process are not particularly limited, but the firing atmosphere and firing temperature can be carried out in the same manner as described in the first firing process, for example, and therefore will not be described here. The firing conditions for the first firing process and the second firing process may be the same or different.

[0047] Here, we have described a method for producing infrared-transmitting material particles containing a composite oxide in two steps, but it is also possible to produce infrared-transmitting material particles containing a composite oxide in three or more steps (n steps). In this case, the descriptions of the second mixed powder preparation step and the second calcination step above can be replaced with the nth mixed powder preparation step and the nth calcination step.

[0048] The nth mixed powder preparation step can be supplied with an intermediate product obtained by calcining the mixed powder prepared in the (n-1) mixed powder preparation step in the (n-1) calcination step.

[0049] In the n-1 mixed powder preparation step, the intermediate product obtained in the n-2 calcination step can be used to mix the intermediate product with the bismuth element source, according to the composition of the intermediate product to be supplied to the nth step. Aside from the above, the configuration can be the same as the second mixed powder preparation step. Therefore, the explanation is omitted.

[0050] Furthermore, the (n-1)th firing process can be carried out under the same firing conditions as the first and second firing processes, except that the mixed powder prepared in the (n-1)th mixed powder preparation process is used, so the explanation is omitted. Note that the conditions for each firing process may be the same or different.

[0051] By performing the steps described above, infrared-transmitting material particles of this embodiment can be obtained. After the firing process is completed, the obtained infrared-transmitting material particles can be crushed, pulverized, sieved, etc., as needed to obtain the desired particle size distribution. [3] Infrared transmitting material particle dispersion Next, an example of the configuration of the infrared-transmitting material particle dispersion of this embodiment will be described.

[0052] The infrared-transmitting material particle dispersion of this embodiment may include a liquid medium and infrared-transmitting material particles disposed in the liquid medium. Infrared-transmitting material particles according to one aspect of this disclosure can be used as the infrared-transmitting material particles.

[0053] Specifically, as schematically shown in Figure 1, for example, the infrared-transmitting material particle dispersion 10 of this embodiment may include infrared-transmitting material particles 11 and a liquid medium 12. The infrared-transmitting material particles 11 can be placed in the liquid medium 12. In the infrared-transmitting material particle dispersion 10 of this embodiment, it is preferable that the infrared-transmitting material particles 11 are dispersed in the liquid medium 12.

[0054] Figure 1 is a schematic diagram, and the infrared-transmitting material particle dispersion 10 of this embodiment is not limited to this form. For example, in Figure 1, the infrared-transmitting material particles 11 are represented by circles and described as spherical particles, but the shape of the infrared-transmitting material particles 11 is not limited to this form and can have any shape. The infrared-transmitting material particles 11 may also have a coating on their surface, for example. In addition to the infrared-transmitting material particles 11 and the liquid medium 12, the infrared-transmitting material particle dispersion 10 may also contain other additives as needed.

[0055] As the liquid medium 12, one or more selected from, for example, water, organic solvents, oils and fats, liquid resins, and liquid plasticizers can be used.

[0056] Various organic solvents can be selected, including alcohol-based, ketone-based, ester-based, hydrocarbon-based, and glycol-based solvents. Specifically, examples of organic solvents include alcohol-based solvents such as isopropyl alcohol, methanol, ethanol, 1-propyl ketone, butanol, pentanol, benzyl alcohol, diacetone alcohol, and 1-methoxy-2-propyl ketone; ketone-based solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ester-based solvents such as 3-methyl-methoxypropyl ketone and n-butyl acetate; and ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. One or more of the following can be selected: glycol derivatives such as ethyl ether, ethylene glycol isopropyl ether, propyl glycol monoethyl ether, propyl glycol methyl ether acetate, and propyl glycol ethyl ether acetate; amides such as formamide, N-methylformamide, dimethylformamide, dimethylacetamide, and N-methyl-2-pyridone; aromatic hydrocarbons such as toluene and xylene; and halogenated hydrocarbons such as ethylene glycol and chlorobenzene.

[0057] However, among these, organic solvents with low polarity are preferred, and more preferably one or more selected from isopropyl alcohol, ethanol, 1-methoxy-2-propylanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propyl glycol monomethyl ether acetate, n-butyl acetate, etc. One or more organic solvents can be used.

[0058] As oils and fats, one or more selected from drying oils such as linseed oil, sunflower oil, and tung oil; semi-drying oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil, and rice bran oil; non-drying oils such as olive oil, coconut oil, palm oil, and dehydrated castor oil; fatty acid monoesters obtained by directly esterifying fatty acids of vegetable oils with monoalcohols; ethers; and petroleum-based solvents such as Isopar® E, Exsol® Hexane, Heptan, E, D30, D40, D60, D80, D95, D110, and D130 (all manufactured by ExxonMobil) can be used.

[0059] As the liquid resin, one or more types selected from, for example, liquid acrylic resin, liquid epoxy resin, liquid polyester resin, liquid urethane resin, etc., can be used.

[0060] As a liquid plasticizer, for example, a liquid plasticizer for plastics can be used.

[0061] The components contained in the infrared-transmitting material particle dispersion are not limited to infrared-transmitting material particles and a liquid medium. The infrared-transmitting material particle dispersion may also contain any additional components as needed.

[0062] For example, the pH of the infrared-transmitting material particle dispersion may be adjusted by adding an acid or alkali as needed.

[0063] Furthermore, in order to further improve the dispersion stability of infrared-transmitting material particles in the infrared-transmitting material particle dispersion and to avoid coarsening of the dispersed particle size due to re-aggregation, the infrared-transmitting material particle dispersion of this embodiment may also contain various surfactants, coupling agents, etc., as dispersants.

[0064] Dispersants such as surfactants and coupling agents can be selected according to the application, but it is preferable that the dispersant has one or more functional groups selected from amino groups, amine-containing groups, hydroxyl groups, carboxyl groups, and epoxy groups. These functional groups adsorb to the surface of infrared-transmitting material particles to prevent aggregation and have the effect of uniformly dispersing infrared-transmitting material particles in infrared-transmitting material dispersions made using infrared-transmitting material particles. It is even more preferable that the dispersant is a polymeric dispersant having one or more functional groups (or functional group group) selected from the above in its molecule.

[0065] Suitable commercially available dispersants include Solspers® 9000, 12000, 17000, 20000, 21000, 24000, 26000, 27000, 28000, 32000, 35100, 54000, 250 (manufactured by Lubrizol Japan Co., Ltd.) and EFKA®. 4008, 4009, 4010, 4015, 4046, 4047, 4060, 4080, 7462, 4020, 4050, 4055, 4400, 4401, 4402, 4403, 4300, 4320, 4330, 4340, 6220, 6225, 6700, 6780, 6782, 8503 (manufactured by F-CA Additives), Azisper (registered trademark) PA111, PB821, PB822, PN411, Phemex L-12 (manufactured by Ajinomoto Fine Techno Co., Ltd.), DisperBYK (registered trademark) 101, 102, 106, 108, 111, 116, 130, 140, 142, 145, 161, 162, 163, 164, 166, 167, 168, 170, 171, 174, 180, 182, 192, 193, 2000, 2001, 2020, 2025, 2050, 2070, 2155, 2164, 220S, 300, 306, 320, 322, 325, 330, 340, 350, 377, 378, 380N, 410, 425, 430 (manufactured by Pick Chemistry Japan Co., Ltd.), Disparon (registered trademark) One or more types selected from 1751N, 1831, 1850, 1860, 1934, DA-400N, DA-703-50, DA-725, DA-705, DA-7301, DN-900, NS-5210, NVI-8514L (manufactured by Kusumoto Kasei Co., Ltd.), Alphon (registered trademark) UC-3000, UF-5022, UG-4010, UG-4035, UG-4070 (manufactured by Toagosei Co., Ltd.), etc.

[0066] Methods for dispersing infrared-transmitting material particles in a liquid medium include, for example, dispersion methods using devices such as bead mills, ball mills, sand mills, paint shakers, and ultrasonic homogenizers. Among these, grinding and dispersion using a media stirring mill such as a bead mill, ball mill, sand mill, or paint shaker that uses a media (beads, balls, Ottawa sand) is preferable from the viewpoint of shortening the time required to achieve the desired average particle size. Grinding and dispersion processing using a media stirring mill simultaneously disperses the infrared-transmitting material particles in the liquid medium and also promotes micronization through collisions between infrared-transmitting material particles and collisions of the media with the infrared-transmitting material particles, thereby further miniaturizing and dispersing the infrared-transmitting material particles. In other words, it is ground and dispersed. [4] Infrared transmitting material particle dispersion Next, an example of the configuration of the infrared-transmitting material particle dispersion of this embodiment will be described.

[0067] The infrared-transmitting material particle dispersion of this embodiment may include a solid medium and infrared-transmitting material particles disposed within the solid medium. Infrared-transmitting material particles according to one aspect of this disclosure can be used as the infrared-transmitting material particles.

[0068] Specifically, as schematically shown in Figure 2, for example, the infrared-transmitting material particle dispersion 20 may include infrared-transmitting material particles 21 and a solid medium 22. The infrared-transmitting material particles 21 can be arranged in the solid medium 22. In this embodiment, it is preferable that the infrared-transmitting material particles 21 are dispersed in the solid medium 22.

[0069] Figure 2 is a schematic diagram, and the infrared-transmitting material particle dispersion of this embodiment is not limited to this form. For example, in Figure 2, the infrared-transmitting material particles 21 are represented by circles and described as spherical particles, but the shape of the infrared-transmitting material particles 21 is not limited to this form and can have any shape. The infrared-transmitting material particles 21 may also have a coating on their surface, for example. In addition to the infrared-transmitting material particles 21 and the solid medium 22, the infrared-transmitting material particle dispersion 20 may also contain other additives as needed. (1) Regarding the components contained in the infrared-transmitting material particle dispersion (1-1) Solid medium The solid medium is not particularly limited, but for example, thermoplastic resins, thermosetting resins, and UV-curing resins can be used as the medium resin. In other words, resin may be used as the solid medium.

[0070] The specific material of the resin used in the solid medium is not particularly limited, but it is preferably one type of resin selected from the group of resins consisting of polyester resin, polycarbonate resin, acrylic resin, styrene resin, polyamide resin, polyethylene resin, vinyl chloride resin, olefin resin, epoxy resin, polyimide resin, fluororesin, ethylene-vinyl acetate copolymer, polyvinyl acetal resin, and ultraviolet curing resin, or a mixture of two or more types of resins selected from the aforementioned group. Polyethylene terephthalate resin can be suitably used as the polyester resin.

[0071] These media resins may also contain polymeric dispersants having one or more functional groups selected from amino groups, hydroxyl groups, carboxyl groups, and epoxy groups in their main skeleton.

[0072] The solid medium is not limited to resins; binders using metal alkoxides can also be used as solid media. Typical examples of such metal alkoxides include those of Si, Ti, Al, and Zr. By hydrolyzing and condensing binders using these metal alkoxides through heating or other means, it is possible to obtain a dispersion of infrared-transmitting material particles in which the solid medium contains oxides. (1-2) Infrared-transmitting material particles Since infrared-transmitting material particles according to one aspect of this disclosure can be used as infrared-transmitting material particles, a detailed explanation is omitted.

[0073] The content ratio of infrared-transmitting material particles in the infrared-transmitting material particle dispersion according to this embodiment is not particularly limited and can be selected according to the properties required for the infrared-transmitting material particle dispersion. For example, the infrared-transmitting material particle dispersion may contain 0.001% by mass or more and 80% by mass or less of infrared-transmitting material particles.

[0074] Furthermore, the infrared-transmitting material particle dispersion of this embodiment has, for example, an infrared-transmitting material particle content per unit area of ​​projection area of, for example, 0.3 g / m². 2 More than 4.0g / m 2 The following is also acceptable.

[0075] The content of infrared-transmitting material particles per projected area is 0.3 g / m². 2 By doing so, it is possible to sufficiently reduce the transmittance of light in the visible light region while increasing the transmittance of light in the infrared region.

[0076] The content of infrared-transmitting material particles per projected area is 4.0 g / m². 2 By doing the following, the transmittance of light in the infrared region can be particularly increased. (1-3) Other additives (Infrared absorbing particles) The particle dispersion of the infrared-transmitting material in this embodiment may further contain infrared-absorbing particles.

[0077] The infrared-transmitting material particle dispersion of this embodiment further contains infrared-absorbing particles, so that at least a portion of the light in the infrared region is absorbed by the infrared-absorbing particles, thereby increasing the selectivity of the wavelength range of light transmitted by the infrared-transmitting material particle dispersion of this embodiment. The infrared-transmitting material particle dispersion of this embodiment further contains infrared-absorbing particles, so that noise in infrared sensors and the like to which the infrared-transmitting material particle dispersion of this embodiment is applied can be reduced, thereby improving the detection accuracy of infrared sensors and the like.

[0078] The infrared absorbing particles that can be used are not particularly limited, as they can be selected according to the optical properties required for the infrared transmitting material particle dispersion, specifically, the wavelength range of the transmitted light.

[0079] When the infrared-transmitting material particle dispersion of this embodiment contains infrared-absorbing particles, the infrared-absorbing particles are preferably made of a material that absorbs infrared radiation in a specific wavelength range within the infrared region.

[0080] The infrared absorbing particles are not particularly limited, but may include, for example, hexaborides.

[0081] The hexaboride may be, for example, a hexaboride represented by the chemical formula XB6.

[0082] In the above compositional formula, element X may be one or more elements selected from La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Y (yttrium), Sm (samarium), Eu (europium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Sr (strontium), and Ca (calcium). The infrared absorbing particles may also be particles made of hexaborides. However, even in this case, the presence of unavoidable impurities introduced during the manufacturing process is not excluded.

[0083] Hexaborides absorb infrared light around 900 nm in the near-infrared region, but transmit infrared light with wavelengths of 1500 nm or higher. By including infrared-absorbing particles containing hexaborides in an infrared-transmitting material particle dispersion, the dispersion can exhibit wavelength selectivity, reducing the transmittance of infrared light around 900 nm while transmitting light with wavelengths of 1500 nm or higher.

[0084] Infrared sensors that use light with wavelengths of 1500 nm or higher for sensing are also known. Therefore, infrared-transmitting material particle dispersions that exhibit wavelength selectivity to transmit light with wavelengths of 1500 nm or higher can be suitably used as covers for infrared sensors.

[0085] When the infrared absorbing particles contain hexaboride, the hexaboride may be lanthanum hexaboride, in which element X in the above composition formula contains lanthanum. Lanthanum hexaboride is known to have a particularly high free electron density among the aforementioned hexaborides. Therefore, among hexaborides, it has particularly excellent absorption characteristics for infrared light around wavelengths of 900 nm to 1100 nm. By including hexaboride in the infrared absorbing particles, the transmittance of infrared light around wavelengths of 900 nm to 1100 nm in the infrared transmitting material particle dispersion can be particularly reduced, and the wavelength selectivity can be particularly enhanced.

[0086] The volume-average particle diameter of the infrared-absorbing particles is not particularly limited and may be, for example, within the same range as in the case of infrared-transmitting material particles. In particular, from the viewpoint of reducing haze in the infrared region of the infrared-transmitting material particle dispersion, it may be 1 nm to 800 nm, 1 nm to 200 nm, 1 nm to 100 nm, or 1 nm to 80 nm. (Plasticizers, etc.) When resin is used as the solid medium, the infrared-transmitting material particle dispersion of this embodiment may also contain known additives such as plasticizers, flame retardants, color inhibitors, and fillers that are typically added to these resins. However, the solid medium is not limited to resin, and binders using metal alkoxides can also be used. Therefore, additives can be selected according to the type of solid medium.

[0087] The shape of the infrared-transmitting material particle dispersion according to this embodiment is not particularly limited, but it can have, for example, a sheet shape, a board shape, or a film shape.

[0088] When infrared-transmitting material particle dispersions in sheet, board, or film form are used as an intermediate layer on a transparent substrate such as laminated glass, the solid medium contained in the infrared-transmitting material particle dispersion may not have sufficient flexibility or adhesion to the transparent substrate as is. In this case, the infrared-transmitting material particle dispersion may contain a plasticizer. Specifically, for example, if the solid medium is polyvinyl acetal resin and the infrared-transmitting material particle dispersion is used for applications such as an intermediate film, it is preferable that the infrared-transmitting material particle dispersion further contains a plasticizer.

[0089] In this case, the plasticizer can be a substance used as a plasticizer in the solid medium used in the infrared-transmitting material particle dispersion of this embodiment. For example, plasticizers used in an infrared-transmitting material particle dispersion composed of polyvinyl acetal resin include plasticizers that are compounds of monohydric alcohols and organic acid esters, ester-based plasticizers such as polyhydric alcohol organic acid ester compounds, and phosphoric acid-based plasticizers such as organophosphate plasticizers. It is preferable that any of these plasticizers be liquid at room temperature. Among these, plasticizers that are ester compounds synthesized from polyhydric alcohols and fatty acids are preferred.

[0090] Furthermore, the infrared-transmitting material particle dispersion of this embodiment may also contain an ultraviolet-absorbing material. By including an ultraviolet-absorbing material in the infrared-transmitting material particle dispersion, the wavelength selectivity of the infrared-transmitting material particle dispersion can be further enhanced. This can further reduce noise in infrared sensors and the like, and further improve the measurement accuracy of infrared sensors and the like. The ultraviolet-absorbing material can absorb at least a portion of the light in the ultraviolet region.

[0091] Ultraviolet light can degrade infrared sensors and infrared-transmitting particle dispersions. Therefore, by including an ultraviolet-absorbing material in the infrared-transmitting particle dispersion, the lifespan of the infrared sensors and the infrared-transmitting particle dispersion itself can be extended. The ultraviolet-absorbing material is not particularly limited and can be selected from known materials depending on the required properties of the infrared-transmitting particle dispersion. (2) Shape of infrared-transmitting material particle dispersion The infrared-transmitting material particle dispersion of this embodiment is not particularly limited in shape and can be selected according to the application. The infrared-transmitting material particle dispersion of this embodiment may have a sheet shape, a board shape, or a film shape. This is because the infrared-transmitting material particle dispersion can be applied to a variety of applications by being in the shape of a sheet, board shape, or film shape. In addition to a plate shape, the board shape also includes interior parts such as dashboards and door panels in the interior of vehicles such as automobiles, and housings of home appliances. (3) Method for producing an infrared-transmitting material particle dispersion The method for manufacturing the infrared-transmitting material particle dispersion of this embodiment is described below. Note that this merely shows an example configuration for the method of manufacturing the infrared-transmitting material particle dispersion, and the previously described method for manufacturing the infrared-transmitting material particle dispersion is not limited to the following example configuration.

[0092] The infrared-transmitting material particle dispersion of this embodiment can be manufactured, for example, using a masterbatch. In this case, the method for manufacturing the infrared-transmitting material particle dispersion of this embodiment may include, for example, the following masterbatch manufacturing step.

[0093] In the masterbatch preparation process, a masterbatch can be prepared in which infrared-transparent material particles are dispersed in a solid medium.

[0094] The specific method for producing a masterbatch is not particularly limited. For example, a masterbatch can be produced by dispersing an infrared-transmitting material particle dispersion or infrared-transmitting material particles in a solid medium and then pelletizing the solid medium.

[0095] Furthermore, as infrared-transmitting material particles, infrared-transmitting material particle dispersion powder obtained by removing the liquid medium from an infrared-transmitting material particle dispersion can also be used.

[0096] For example, a mixture can be prepared by uniformly mixing an infrared-transmitting material particle dispersion, infrared-transmitting material particles, or infrared-transmitting material particle dispersion powder with a solid medium in powder or pellet form, and other additives as needed. Then, a masterbatch can be manufactured by kneading this mixture in a vented single-screw or twin-screw extruder and processing the molten-extruded strand into pellets by cutting. In this case, the pellets can be cylindrical or prismatic in shape. It is also possible to use the so-called hot-cut method, in which the molten extruded material is cut directly, when producing pellets. In this case, a shape close to a sphere is common.

[0097] Furthermore, when using an infrared-transmitting material particle dispersion as a raw material in the masterbatch preparation process, it is preferable to reduce or remove the liquid medium derived from the infrared-transmitting material particle dispersion. In this case, there is no particular limit to the extent to which the liquid medium contained in the infrared-transmitting material particle dispersion is removed. For example, it is preferable to remove the liquid medium from the infrared-transmitting material particle dispersion to an amount that is acceptable to remain in the masterbatch. If a liquid plasticizer is used as the liquid medium, the entire amount of the liquid plasticizer may remain in the infrared-transmitting material particle dispersion.

[0098] The method for reducing and removing the liquid medium contained in the infrared-transmitting material particle dispersion or a mixture of the infrared-transmitting material particle dispersion and a solid medium is not particularly limited. For example, it is preferable to carry out a drying process in which the infrared-transmitting material particle dispersion is dried under reduced pressure. Specifically, the infrared-transmitting material particle dispersion is dried under reduced pressure while being stirred to separate the infrared-transmitting material particle-containing composition from the components of the liquid medium. Examples of equipment used for this reduced-pressure drying include a vacuum-stirring type dryer, but any equipment having the above function is acceptable and is not particularly limited. Furthermore, the pressure value during the reduced pressure in the drying process is selected as appropriate.

[0099] By using a vacuum drying method to remove the liquid medium, the efficiency of removing the liquid medium and other substances originating from the infrared-transmitting material particle dispersion is improved. Furthermore, since the infrared-transmitting material particle dispersion powder obtained after vacuum drying and the raw material infrared-transmitting material particle dispersion liquid are not exposed to high temperatures for a long period of time, aggregation of the infrared-transmitting material particles dispersed in the infrared-transmitting material particle dispersion powder and the infrared-transmitting material particles dispersed in the infrared-transmitting material particle dispersion liquid does not occur, which is preferable. In addition, the productivity of the infrared-transmitting material particle dispersion powder and other substances is increased, and the recovery of evaporated liquid medium and other solvents is easy, which is also preferable from an environmental perspective.

[0100] In the infrared-transmitting material particle dispersion powder obtained after the drying process, it is preferable to thoroughly remove solvent components with a boiling point of 120°C or lower. For example, it is preferable that the residual amount of such solvent components be 2.5% by mass or less. If the residual solvent components are 2.5% by mass or less, bubbles will not be generated when the infrared-transmitting material particle dispersion powder is processed into, for example, an infrared-transmitting material particle dispersion, and the appearance and optical properties will be well maintained. Furthermore, if the residual solvent components in the infrared-transmitting material particle dispersion powder are 2.5% by mass or less, when the infrared-transmitting material particle dispersion powder is stored for a long period of time, aggregation due to natural drying of the residual solvent components will not occur, and long-term stability will be maintained.

[0101] The resulting masterbatch can be mixed with a solid medium to adjust its dispersion concentration while maintaining the dispersion state of the infrared-transmitting material particles contained in the masterbatch, which is an infrared-transmitting material particle dispersion.

[0102] Furthermore, the method for producing the infrared-transmitting material particle dispersion of this embodiment may optionally include a molding step in which the obtained masterbatch, or a masterbatch to which a solid medium has been added as described above, is molded to form an infrared-transmitting material particle dispersion of a desired shape.

[0103] The specific method for forming the infrared-transmitting material particle dispersion is not particularly limited, but known methods such as extrusion molding and injection molding can be used.

[0104] In the molding process, for example, infrared-transmitting material particle dispersions can be manufactured in the form of sheets, boards, or films, which are formed into planar or curved shapes. The method for forming the material into sheets, boards, or films is not particularly limited, and various known methods can be used. For example, calendering rolls, extrusion, casting, inflation, injection molding, etc., can be used.

[0105] The method for producing the infrared-transmitting material particle dispersion of this embodiment is not limited to the form having the masterbatch preparation step described above.

[0106] For example, the above-mentioned infrared-transmitting material particle dispersion powder may be mixed with a solid medium powder or pellet, melt-kneaded, and manufactured without going through a masterbatch.

[0107] For example, the method for producing the infrared-transmitting material particle dispersion of this embodiment may include the following precursor liquid preparation step and infrared-transmitting material particle dispersion production step.

[0108] In the precursor preparation step, a precursor for infrared-transmitting material particle dispersions can be prepared by mixing a solid medium monomer, oligomer, and an uncured, liquid solid medium precursor with infrared-transmitting material particles, infrared-transmitting material particle dispersion powder, or infrared-transmitting material particle dispersion liquid.

[0109] In the process for producing infrared-transmitting material particle dispersions, a solid medium precursor such as a monomer is cured in an infrared-transmitting material particle dispersion precursor liquid by chemical reactions such as condensation or polymerization to produce an infrared-transmitting material particle dispersion.

[0110] For example, when using acrylic resin as the solid medium, the precursor preparation step involves mixing acrylic monomer or an acrylic-based UV-curing resin with infrared-transmitting material particles to obtain an infrared-transmitting material particle dispersion precursor.

[0111] Next, in the infrared-transmitting material particle dispersion preparation process, an infrared-transmitting material particle dispersion precursor liquid is filled into a predetermined mold or the like and radical polymerization is performed to obtain an infrared-transmitting material particle dispersion using acrylic resin.

[0112] When using a resin that hardens by crosslinking as the solid medium, the dispersion can be obtained by crosslinking the infrared-transmitting material particle dispersion precursor liquid, similar to the case where acrylic resin is used as described above. (4) Examples of application The infrared-transmitting material particle dispersion of this embodiment can be used in various ways, and its use and application are not particularly limited. Below, examples of applications of the infrared-transmitting material particle dispersion of this embodiment will be described, including infrared-transmitting interlayers, infrared-transmitting laminates, and infrared-transmitting substrates. (4-1) Infrared-transmitting interlayers, infrared-transmitting laminates The infrared-transmitting laminate of this embodiment may have a laminated structure comprising an infrared-transmitting material particle dispersion according to one aspect of the present disclosure and a transparent substrate. The infrared-transmitting laminate of this embodiment may have an infrared-transmitting material particle dispersion according to one aspect of the present disclosure and a transparent substrate as elements, and may be a laminate formed by laminating these together.

[0113] An example of an infrared-transmitting laminate is one in which two or more transparent substrates and an infrared-transmitting material particle dispersion according to one aspect of this disclosure are arranged between the multiple transparent substrates. In this case, the infrared-transmitting material particle dispersion can be arranged, for example, between the multiple transparent substrates and used as an infrared-transmitting interlayer.

[0114] In the case of an infrared-transmitting laminate, specifically as shown in Figure 3, a schematic cross-sectional view along the lamination direction of the transparent substrate and the infrared-transmitting material particle dispersion, the infrared-transmitting laminate 30 can have multiple transparent substrates 311 and 312 and an infrared-transmitting material particle dispersion 32. The infrared-transmitting material particle dispersion 32 can be placed between the multiple transparent substrates 311 and 312. Figure 3 shows an example with two transparent substrates 311 and 312, but the configuration is not limited to this.

[0115] The infrared-transmitting material particle dispersion that forms the infrared-transmitting interlayer is preferably in the shape of a sheet, a board, or a film.

[0116] The substrate can preferably be one or more selected from plate glass, plate-shaped plastic, or film-shaped plastic. The optical properties of the substrate are not particularly limited and can be selected according to the optical properties required for the infrared-transmitting laminate. The substrate may be a transparent substrate that does not block light in the infrared region, i.e., a substrate that transmits light in the infrared region, or a transparent substrate that does not block light in the visible light region or the infrared light region.

[0117] The substrate may transmit only at least a portion of the infrared light region required by, for example, an infrared sensor, and block at least a portion of the remaining infrared light region not used by the infrared sensor. For this reason, the substrate may contain infrared absorbing particles. The substrate may also contain ultraviolet absorbing materials. As infrared absorbing particles or ultraviolet absorbing materials, for example, the materials described in the section on infrared transmitting material particle dispersions can be used.

[0118] When using plastic as a base material, the type of plastic is not particularly limited and can be selected according to the application. For example, one or more types can be selected from polycarbonate resin, acrylic resin, polyester resin, polyamide resin, vinyl chloride resin, olefin resin, epoxy resin, polyimide resin, ionomer resin, fluororesin, etc. Polyethylene terephthalate resin can be suitably used as the polyester resin.

[0119] By interposing an infrared-transmitting material particle dispersion according to one aspect of this disclosure as a component of the intermediate layer sandwiched between multiple substrates, an infrared-transmitting laminate structure, which is an excellent type of infrared-transmitting laminate, can be created.

[0120] The above-mentioned infrared-transmitting laminate can also be formed by bonding and integrating multiple opposing substrates, with an infrared-transmitting material particle dispersion sandwiched between them, using a known method.

[0121] When using an infrared-transmitting material particle dispersion according to one aspect of this disclosure as an infrared-transmitting interlayer, the solid medium can be the one described for the infrared-transmitting material particle dispersion. However, from the viewpoint of increasing the adhesion strength between the infrared-transmitting interlayer and the transparent substrate, the solid medium is preferably polyvinyl acetal resin.

[0122] The infrared-transmitting interlayer of this embodiment can be manufactured by a method for manufacturing an infrared-transmitting material particle dispersion according to one aspect of the present disclosure, and can be an infrared-transmitting interlayer having any of the following shapes: sheet, board, or film.

[0123] Furthermore, if the infrared-transmitting interlayer does not have sufficient flexibility or adhesion to the substrate, it is preferable to add a liquid plasticizer for the media resin. For example, if the media resin used for the infrared-transmitting interlayer is polyvinyl acetal resin, adding a liquid plasticizer for polyvinyl acetal resin is beneficial for improving adhesion to the transparent substrate.

[0124] As a plasticizer, substances used as plasticizers for solid resins can be used. For example, plasticizers applied to infrared-transmitting material particle dispersions using polyvinyl acetal resin as a solid medium include plasticizers that are compounds of monohydric alcohols and organic acid esters, ester-based plasticizers such as polyhydric alcohol organic acid ester compounds, and phosphoric acid-based plasticizers such as organophosphate plasticizers. It is preferable that all plasticizers are liquid at room temperature. Among these, plasticizers that are ester compounds synthesized from polyhydric alcohols and fatty acids are preferred.

[0125] The intermediate layer of the infrared-transmitting laminate may be composed solely of the infrared-transmitting interlayer according to this embodiment.

[0126] The infrared-transmitting interlayer of this embodiment is one form of an infrared-transmitting material particle dispersion. The infrared-transmitting material particle dispersion according to this embodiment can be used without being sandwiched between two or more transparent substrates. In other words, the infrared-transmitting material particle dispersion according to this embodiment can function as an infrared-transmitting material particle dispersion on its own.

[0127] The infrared-transmitting laminate according to this embodiment is not limited to the form in which an infrared-transmitting material particle dispersion is arranged between transparent substrates as described above, but can take any configuration as long as it has a laminated structure including an infrared-transmitting material particle dispersion and a transparent substrate. (4-2) Infrared-transmitting substrate The infrared-transmitting substrate of this embodiment comprises a substrate and an infrared-transmitting layer disposed on at least one surface of the substrate, wherein the infrared-transmitting layer can be an infrared-transmitting material particle dispersion according to one aspect of the present disclosure.

[0128] Specifically, as shown in Figure 4, a schematic cross-sectional view along the lamination direction of the substrate and the infrared-transmitting layer, the infrared-transmitting substrate 40 may have a substrate 41 and an infrared-transmitting layer 42. The infrared-transmitting layer 42 can be arranged on at least one surface 41A of the substrate 41.

[0129] The infrared-transmitting substrate of this embodiment may have a substrate as described above. Preferably, one or more substrates selected from, for example, a transparent film substrate and a transparent glass substrate can be used. The optical properties of the substrate are not particularly limited and can be selected according to the optical properties required for the infrared-transmitting substrate. The substrate may be a transparent substrate that does not block light in the infrared region, i.e., transmits light in the infrared region, or it may be a transparent substrate that does not block light in the visible light region or the infrared region.

[0130] The substrate may transmit only at least a portion of the infrared light region required by, for example, an infrared sensor, and block at least a portion of the remaining infrared light region not used by the infrared sensor. For this reason, the substrate may contain infrared absorbing particles. The substrate may also contain ultraviolet absorbing materials. As infrared absorbing particles or ultraviolet absorbing materials, for example, the materials described in the section on infrared transmitting material particle dispersions can be used.

[0131] The film substrate is not limited to a film shape; for example, it may be in the shape of a board or a sheet.

[0132] As the material for the film substrate, one or more selected from polyester resin, acrylic resin, urethane resin, polycarbonate resin, polyethylene resin, ethylene vinyl acetate copolymer, vinyl chloride resin, fluororesin, etc., can be suitably used and can be used according to various purposes. However, the material for the film substrate is preferably polyester resin, and more preferably polyethylene terephthalate resin (PET resin). In other words, the film substrate is preferably a polyester resin film, and more preferably a polyethylene terephthalate resin film.

[0133] When a film substrate is used as the base material, the surface of the film substrate may be surface-treated to facilitate adhesion with the infrared-transmitting layer.

[0134] Furthermore, in order to improve the adhesion between the glass substrate or film substrate and the infrared-transmitting layer, an intermediate layer may be formed on the glass substrate or film substrate, and the infrared-transmitting layer may be formed on the intermediate layer. The composition of the intermediate layer is not particularly limited and can be formed from, for example, a polymer film, a metal layer, an inorganic layer (for example, an inorganic oxide layer such as silica, titania, or zirconia), or an organic / inorganic composite layer.

[0135] Since the infrared-transmitting material particle dispersion has already been described, its explanation will be omitted here. The shape of the infrared-transmitting material particle dispersion is not particularly limited, but it is preferably in the form of a sheet, board, or film.

[0136] A method for manufacturing the infrared-transmitting substrate of this embodiment will be described.

[0137] The infrared-transmitting substrate of this embodiment can be manufactured, for example, by using the infrared-transmitting material particle dispersion liquid described above to form an infrared-transmitting layer on the substrate, which is an infrared-transmitting material particle dispersion in which infrared-transmitting material particles are dispersed in a solid medium.

[0138] Therefore, the method for manufacturing the infrared-transmitting substrate of this embodiment may include, for example, the following coating step and infrared-transmitting layer formation step.

[0139] In the coating process, a coating solution containing the aforementioned infrared-transmitting material particle dispersion can be applied to the surface of the substrate.

[0140] In the infrared-transmitting layer formation process, the infrared-transmitting layer can be formed after the liquid medium in the coating solution has been evaporated.

[0141] The coating solution used in the coating process can be prepared, for example, by adding and mixing a resin, a solid medium such as a metal alkoxide, or a solid medium precursor to an infrared-transmitting material particle dispersion according to one aspect of this disclosure.

[0142] As previously described, a solid media precursor means one or more selected from monomers, oligomers, and uncured, liquid solid media.

[0143] When an infrared-transmitting layer, which is a coating film, is formed on a substrate, the infrared-transmitting layer becomes a state in which infrared-transmitting material particles are dispersed in a solid medium. Therefore, the infrared-transmitting layer becomes an infrared-transmitting material particle dispersion. In this way, an infrared-transmitting substrate can be manufactured by providing an infrared-transmitting material particle dispersion on the surface of the substrate.

[0144] Solid media and solid media precursors have been explained in "(1) Components contained in infrared-transmitting material particle dispersions" and "(3) Method for producing infrared-transmitting material particle dispersions," so their explanation is omitted here.

[0145] The method for applying the coating solution to the substrate in order to provide an infrared-transmitting layer on the substrate is not particularly limited, as long as it is a method that can uniformly apply the coating solution to the surface of the substrate. Examples include bar coating, gravure coating, spray coating, dip coating, spin coating, screen printing, roll coating, and flow coating.

[0146] Here, we will explain the procedure for creating an infrared-transmitting layer on a substrate surface, using as an example a case where an ultraviolet-curing resin is used as the solid medium and the coating solution is applied using the bar coating method to form an infrared-transmitting layer.

[0147] A coating solution, whose concentration and additives have been appropriately adjusted to have adequate leveling properties, is applied to the substrate using a wire bar with a bar number that satisfies the desired thickness of the infrared-transmitting layer and the content of infrared-transmitting material particles. After removing the solvent, such as the liquid medium, contained in the coating solution by drying, the solid medium is cured by irradiation with ultraviolet light, thereby forming an infrared-transmitting coating layer on the substrate.

[0148] The drying conditions for the coating film vary depending on the type and proportion of each component and solvent used, but typically, it can be carried out at a temperature of 60°C to 140°C for 20 seconds to 10 minutes. There are no particular restrictions on ultraviolet irradiation, and ultraviolet exposure equipment such as ultra-high pressure mercury lamps can be suitably used.

[0149] In addition, the adhesion between the substrate and the infrared-transmitting layer, the smoothness of the coating film during coating, and the drying properties of the organic solvent can be manipulated by pre- and post-processing steps (pre-processing and post-processing) before the formation of the infrared-transmitting layer. Examples of such pre- and post-processing steps include a substrate surface treatment step, a pre-bake (pre-heating of the substrate) step, and a post-bake (post-heating of the substrate) step, which can be selected as appropriate. Preferably, the heating temperature in the pre-bake and post-bake steps is 80°C to 200°C, and the heating time is 30 seconds to 240 seconds.

[0150] The method for manufacturing the infrared-transmitting substrate of this embodiment is not limited to the method described above. Other examples of the method for manufacturing the infrared-transmitting substrate of this embodiment include the following configurations which include a coating and drying step of an infrared-transmitting material particle dispersion, or a binder coating and curing step.

[0151] In the infrared-transmitting material particle dispersion coating and drying process, the infrared-transmitting material particle dispersion according to one embodiment of the present disclosure is coated onto the surface of a substrate and dried.

[0152] The binder application and curing process involves applying a binder, such as a resin, a solid medium like a metal alkoxide, or a solid medium precursor, onto a surface coated with an infrared-transmitting material particle dispersion, and then curing it.

[0153] In this case, a film in which infrared-transmitting material particles are dispersed is formed on the surface of the substrate by the coating and drying process of the infrared-transmitting material particle dispersion. The infrared-transmitting material particle dispersion can be applied by the same method as described in the coating process of the previously described method for manufacturing the infrared-transmitting substrate.

[0154] Then, by applying a binder to a film on which the infrared-transmitting material particles are dispersed and curing it, the cured binder is arranged between the infrared-transmitting material particles, and an infrared-transmitting layer can be formed.

[0155] The infrared-transmitting substrate may also have a further coating layer on the surface of the infrared-transmitting material particle dispersion; in other words, it may have a multilayer film.

[0156] The coating layer can be a coating film of an oxide containing, for example, one or more elements selected from Si, Ti, Zr, and Al. In this case, the coating layer can be formed, for example, by applying a coating solution containing one or more elements selected from alkoxides containing one or more elements from Si, Ti, Zr, and Al, and partially hydrolyzed condensed polymers of said alkoxides, onto an infrared-transmitting layer, and then heating.

[0157] By providing a coating layer, the coated components fill the gaps between the deposited infrared-transmitting material particles in the first layer, forming a film that suppresses the refraction of visible light, thereby further reducing the film's haze value. Furthermore, it improves the adhesion of the infrared-transmitting material particles to the substrate.

[0158] Here, as a method for forming a coating film consisting of an alkoxide containing one or more of Si, Ti, Zr, and Al, or a partially hydrolyzed condensed polymer thereof, on infrared-transmitting material particles alone or on a film containing infrared-transmitting material particles, a coating method is preferred from the viewpoint of ease of film formation and cost.

[0159] As the coating solution used in the above coating method, a solvent such as water or alcohol containing one or more alkoxides containing Si, Ti, Zr, or Al, or one or more partially hydrolyzed condensed polymers of said alkoxides, can be suitably used. The content of the alkoxides etc. in the above coating solution is not particularly limited, but for example, it is preferable to have 40% by mass or less in terms of oxides in the coating obtained after heating. In addition, the pH can be adjusted by adding acids or alkalis as needed.

[0160] By applying the coating solution as a second layer onto a film mainly composed of infrared-transmitting material particles and heating it, an oxide film containing one or more materials selected from Si, Ti, Zr, and Al can be easily formed as the coating layer. It is also preferable to use an organosilazane solution as the binder component used in the coating solution or as a component of the coating solution.

[0161] The substrate heating temperature after application of the infrared-transmitting material particle dispersion containing one or more metal alkoxides from Si, Ti, Zr, and Al, and their hydrolyzed polymers, or the coating solution is not particularly limited. For example, the substrate heating temperature is preferably 100°C or higher, and more preferably above the boiling point of the solvent in the coating solution such as the infrared-transmitting material particle dispersion.

[0162] This is because when the substrate heating temperature is 100°C or higher, the polymerization reaction of the metal alkoxide or the hydrolyzed polymer of the metal alkoxide contained in the coating film can be completed. Furthermore, when the substrate heating temperature is 100°C or higher, there is almost no residue of the solvent, such as water or organic solvent, in the film, so these solvents do not cause a reduction in the transmittance of light in the infrared region in the heated film.

[0163] The infrared-transmitting material particle dispersion of this embodiment can block visible light and transmit infrared light, making it suitable for use in infrared sensors and covers for electronic devices that utilize infrared light, such as infrared cameras. [Examples]

[0164] The present invention will be described more specifically below with reference to examples, but the present invention is not limited thereto. [1] Evaluation method First, the evaluation methods in the following examples and comparative examples will be explained. (1) Volume-average particle diameter The particle size distribution of infrared-transmitting material particles in the examples and comparative examples was measured using a particle size distribution analyzer (Otsuka Electronics, Model: ELSZneo) based on the dynamic light scattering method analyzed by frequency analysis. The measurement conditions were a particle refractive index of 1.81 and a non-spherical particle shape. The background was measured using methyl isobutyl ketone, with a solvent refractive index of 1.40. The volume-average particle diameter was then determined from the obtained particle size distribution. (2) Crystal structure The crystal structure of the composite bismuth oxide contained in the infrared-transmitting material particles prepared in the examples and comparative examples was identified. Specifically, the X-ray diffraction pattern of the powder containing the infrared-transmitting material particles was measured using powder X-ray diffraction (θ-2θ method) with a powder X-ray diffractometer (Bruker D2 PHASER). The crystal structure of the composite bismuth oxide contained in the particles was identified from the obtained X-ray diffraction pattern. (3) Optical properties of infrared-transmitting material dispersions The optical properties of the infrared-transmitting laminated structures, which are resin sheets or infrared-transmitting laminates, prepared in the examples and comparative examples were measured using a spectrophotometer (Hitachi High-Tech Science Co., Ltd., Model: UH4150). Transmitted light profiles were measured at 5 nm intervals in the wavelength range of 200 nm to 2600 nm, and the visible light transmittance was determined according to JIS R 3106 (2019).

[0165] Furthermore, the transmittance at wavelengths of 905 nm and 1550 nm was determined from the transmittance profile. [2] Manufacturing conditions for the examples and comparative examples [Example 1] Barium oxide powder (BaO, manufactured by Sigma-Aldrich, 99.99% purity) and bismuth oxide powder (Bi2O3, manufactured by Fujifilm Wako Pure Chemical Industries, 99.9% purity) were used as raw material powders.

[0166] After weighing out the two raw material powders so that the ratio of barium (Ba) to bismuth (Bi) was Ba:Bi = 1:1, they were thoroughly mixed using an automatic grinder to obtain a mixed powder.

[0167] The resulting mixed powder was placed in an alumina crucible and subjected to a firing treatment at 500°C for 2 hours in an atmospheric environment. Powder XRD measurements were performed on the resulting powder (hereinafter also referred to as infrared-transmitting material particle A), and a diffraction chart corresponding to the peak list of the International Diffraction Database (ICDD) number [01-078-0599] was obtained. Therefore, it was confirmed that the crystal structure of the composite bismuth oxide contained in infrared-transmitting material particle A is monoclinic and has the chemical formula BaBiO3.

[0168] A mixture (slurry) was prepared by mixing 10% by mass of infrared-transmitting material particles A, 10% by mass of an acrylic polymer dispersant having an amine-containing functional group, and 80% by mass of methyl isobutyl ketone. The acrylic polymer dispersant used had an amine value of 48 mgKOH / g and a decomposition temperature of 250°C. Hereafter, it will also be referred to as dispersant a.

[0169] The resulting mixture (slurry) was placed in a glass bottle with φ0.3 mm ZrO2 beads, loaded into a paint shaker, and subjected to grinding and dispersion treatment for 5 hours to obtain the infrared-transmitting material particle dispersion according to Example 1 (hereinafter sometimes referred to as infrared-transmitting material particle dispersion A). The volume-average particle diameter of the infrared-transmitting material particles contained in infrared-transmitting material particle dispersion A was measured to be 63 nm.

[0170] Dispersant a was added to the infrared-transmitting material particle dispersion A, and the mass ratio of dispersant a to infrared-transmitting material particles A was adjusted to [dispersant a]:[infrared-transmitting material particles A]=3:1 to obtain an infrared-transmitting material particle dispersion. Next, methyl isobutyl ketone was removed from this infrared-transmitting material particle dispersion using a spray dryer to obtain infrared-transmitting material particle dispersion powder (hereinafter sometimes referred to as dispersion powder A).

[0171] A composition for manufacturing an infrared-transmitting sheet (hereinafter also referred to as Composition A) was prepared by adding and mixing dispersion powder A to a polycarbonate resin, which is a thermoplastic resin, so that the visible light transmittance of the resin sheet (2.0 mm thick), which is a dispersion of infrared-transmitting material particles to be manufactured, is approximately 5%. In addition, Tinuvin® 326 (manufactured by BASF Ltd., a benzotriazole-based ultraviolet absorber), which is an ultraviolet absorber, was added to Composition A at a ratio of 0.1% by mass.

[0172] Composition A was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calender roll method, thereby obtaining a resin sheet which is an infrared-transmitting material particle dispersion according to Example 1. The content of infrared-transmitting material particles per projected area of ​​the obtained resin sheet was 2.2 g / m². 2 That's what happened.

[0173] The optical properties of the infrared-transmitting material particle dispersion (resin sheet) obtained in Example 1 were measured, and the visible light transmittance was 5.0%, the transmittance at a wavelength of 905 nm was 66.8%, and the transmittance at a wavelength of 1550 nm was 87.1%. The above measurement results are shown in Table 1. The obtained transmittance curve is shown in Figure 5. Figure 5 also shows the intensity of sunlight. [Example 2] Dispersion powder A, produced in Example 1, was added to a polycarbonate resin, which is a thermoplastic resin, so that the visible light transmittance of the resin sheet (2.0 mm thick), which is a dispersion of infrared-transmitting material particles produced, would be approximately 10%. Except for the above, a composition for producing an infrared-transmitting sheet (composition B) was prepared under the same conditions as in Example 1. In addition, an ultraviolet absorber was added to composition B under the same conditions as in composition A. The same applies to the compositions in the following other examples and comparative examples.

[0174] Composition B was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calender roll method, thereby obtaining a resin sheet which is an infrared-transmitting material particle dispersion according to Example 2. The content of infrared-transmitting material particles per projected area of ​​the obtained resin sheet was 1.7 g / m². 2 That's what happened.

[0175] The optical properties of the infrared-transmitting material particle dispersion (resin sheet) obtained in Example 2 were measured, and the visible light transmittance was 9.9%, the transmittance at a wavelength of 905 nm was 71.7%, and the transmittance at a wavelength of 1550 nm was 87.4%. The above measurement results are shown in Table 1. The obtained transmittance curve is shown in Figure 5. [Example 3] Dispersion powder A, produced in Example 1, was added to a polycarbonate resin, which is a thermoplastic resin, so that the visible light transmittance of the resin sheet (2.0 mm thick), which is a dispersion of infrared-transmitting material particles produced, would be approximately 20%. Except for the above, a composition for producing an infrared-transmitting sheet (composition C) was prepared under the same conditions as in Example 1.

[0176] Composition C was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calender roll method, thereby obtaining a resin sheet which is an infrared-transmitting material particle dispersion according to Example 3. The content of infrared-transmitting material particles per unit of projected area of ​​the obtained resin sheet was 1.1 g / m². 2 That's what happened.

[0177] The optical properties of the infrared-transmitting material particle dispersion (resin sheet) obtained in Example 3 were measured, and the visible light transmittance was 20.3%, the transmittance at a wavelength of 905 nm was 77.4%, and the transmittance at a wavelength of 1550 nm was 87.6%. The above measurement results are shown in Table 1. The obtained transmittance curve is shown in Figure 5. [Example 4] Strontium oxide powder (SrO, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., purity 99.5%) and bismuth oxide powder (Bi2O3, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., purity 99.9%) were used as raw material powders.

[0178] Two types of raw material powders were weighed out so that the ratio of strontium (Sr) to bismuth (Bi) was Sr:Bi = 1.8:1. These were then thoroughly mixed using an automatic grinder to obtain a mixed powder.

[0179] The resulting mixed powder was placed in an alumina crucible and subjected to a firing treatment at 800°C for 2 hours in an atmospheric environment. Powder XRD measurements were performed on the resulting powder (hereinafter sometimes referred to as infrared-transmitting material particle D), and a diffraction chart corresponding to the peak list of the International Diffraction Database (ICDD) number "01-081-2408" was obtained. From this, it was determined that the crystal structure of the composite bismuth oxide contained in infrared-transmitting material particle D is cubic, and the compositional formula is Sr 10 Bi6O 24 It was confirmed that it possesses [the characteristic]. However, the reason why the Sr:Bi ratio in the composition formula of infrared-transmitting material particle D (10:6 = 1.67) differs from the ratio in the powder used in manufacturing (1.8:1) is unclear, but it is possible that some of the Sr component volatilized during the calcination process.

[0180] An infrared-transmitting material particle dispersion (hereinafter also referred to as infrared-transmitting material particle dispersion D) was obtained under the same conditions and procedures as in Example 1, except that infrared-transmitting material particle D was used instead of infrared-transmitting material particle A. The volume-average particle diameter of the infrared-transmitting material particles contained in infrared-transmitting material particle dispersion D was measured to be 29 nm.

[0181] Then, using the same conditions and procedure as in Example 1, except that infrared-transmitting material particle dispersion D was used instead of infrared-transmitting material particle dispersion A, an infrared-transmitting material particle dispersion powder (hereinafter also referred to as dispersion powder D) was obtained.

[0182] Dispersion powder D was added to a polycarbonate resin, which is a thermoplastic resin, so that the visible light transmittance of the resin sheet (2.0 mm thick), which is a dispersion of infrared-transmitting material particles to be manufactured, was approximately 10%. Except for the above, the composition for manufacturing the infrared-transmitting sheet (composition D) was prepared under the same conditions as in Example 1.

[0183] Composition D was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calender roll method, resulting in a resin sheet which is an infrared-transmitting material particle dispersion according to Example 4. The content of infrared-transmitting material particles per projected area of ​​the sheet material in the obtained resin sheet was 2.5 g / m². 2 That's what happened.

[0184] The optical properties of the infrared-transmitting material particle dispersion (resin sheet) obtained in Example 4 were measured, and the visible light transmittance was 10.3%, the transmittance at a wavelength of 905 nm was 69.5%, and the transmittance at a wavelength of 1550 nm was 80.9%. The above measurement results are shown in Table 1. [Example 5] For polycarbonate resin, a thermoplastic resin, the amount of infrared-transmitting material particles added per projected area of ​​the manufactured infrared-transmitting material particle dispersion resin sheet (2.0 mm thick) is 1.7 g / m². 2 Dispersed powder A was added in such a manner (i.e., in the same proportion as in Example 2). Furthermore, a known dispersed powder of lanthanum hexaboride particles (average particle size 20 nm) was added, with the amount of lanthanum hexaboride particles added per projected area of ​​the resin sheet (2.0 mm thick) being 0.17 g / m². 2 The mixture was added in such a manner. Except for the points mentioned above, the same conditions as in Example 1 were used to prepare a composition for manufacturing an infrared-transmitting sheet (Composition E), which was prepared by mixing polycarbonate resin, dispersed powder A, dispersed powder of lanthanum hexaboride particles, and an ultraviolet absorber.

[0185] Composition E was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calender roll method, thereby obtaining a resin sheet which is an infrared-transmitting material particle dispersion according to Example 5. The content of infrared-transmitting material particles per unit of projected area of ​​the obtained resin sheet was 1.7 g / m². 2 The amount of infrared-absorbing particles per unit area of ​​the sheet material is 0.17 g / m². 2 That's what happened.

[0186] The optical properties of the infrared-transmitting material particle dispersion (resin sheet) obtained in Example 5 were measured, and the visible light transmittance was 6.5%, the transmittance at a wavelength of 905 nm was 9.1%, and the transmittance at a wavelength of 1550 nm was 67.0%. The above measurement results are shown in Table 1. The obtained transmittance curve is shown in Figure 5. [Example 6] A resin composition powder was obtained by mixing polyvinyl butyral resin powder, which is a thermoplastic resin, with triethylene glycol di-2-ethylhexanoate, a plasticizer, in a ratio of [polyvinyl butyral resin]:[triethylene glycol di-2-ethylhexanoate] = 100:40 (by weight).

[0187] Dispersion powder A, prepared in Example 1, was added to the resin composition powder so that the visible light transmittance of the resin sheet (0.7 mm thick), which is the infrared-transmitting material particle dispersion to be manufactured, would be approximately 10%. Except for the above, the composition for manufacturing the infrared-transmitting resin sheet (composition F) was prepared under the same conditions as in Example 1.

[0188] Composition F was kneaded at 200°C using a twin-screw extruder, extruded through a T-die, and obtained a 0.7 mm thick sheet material by calender roll method, thereby obtaining a resin sheet which is an infrared-transmitting material particle dispersion according to Example 6. The content of infrared-transmitting material particles per projected area of ​​the sheet material in the obtained resin sheet was 1.7 g / m². 2 That's what happened.

[0189] The obtained resin sheet was sandwiched between two blue glass plates (3 mm thick), and then pressed in a vacuum atmosphere using a press device heated to 120°C to produce an infrared-transmitting laminated structure, which is the infrared-transmitting laminate according to Example 6.

[0190] The optical properties of the infrared-transmitting laminated structure obtained in Example 6 were measured, and the visible light transmittance was 9.9%, the transmittance at a wavelength of 905 nm was 57.8%, and the transmittance at a wavelength of 1550 nm was 75.5%. The above measurement results are shown in Table 1. [Comparative Example 1] Polycarbonate resin, a thermoplastic resin, was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calender roll method, thus obtaining a resin sheet without infrared-transmitting material particles, as described in Comparative Example 1. At this time, the amount of infrared-transmitting material particles added per unit projected area of ​​the sheet material was 0 g / m². 2 That's what happened.

[0191] The optical properties of the resin sheet obtained in Comparative Example 1 were measured, and the visible light transmittance was 88.0%, the transmittance at a wavelength of 905 nm was 90.0%, and the transmittance at a wavelength of 1550 nm was 88.2%. The measurement results are shown in Table 1. The obtained transmittance curve is shown in Figure 5. [Comparative Example 2] A carbon black particle dispersion was obtained under the same conditions and procedure as in Example 1, except that carbon black particles were used instead of infrared-transmitting material particles A. The volume-average particle diameter of the carbon black particles contained in the carbon black particle dispersion was measured to be 23 nm. Then, under the same conditions and procedure as in Example 1, except that a carbon black particle dispersion was used instead of infrared-transmitting material particle dispersion A, a carbon black particle dispersion powder according to Comparative Example 2 was obtained.

[0192] Carbon black particle dispersion powder was added to a polycarbonate resin, which is a thermoplastic resin, so that the visible light transmittance of the resin sheet (2.0 mm thick), which is the carbon black particle dispersion produced, was approximately 5%. Except for the above, the composition for producing the resin sheet (composition B1) was prepared under the same conditions as in Example 1.

[0193] Composition B1 was kneaded at 280°C using a twin-screw extruder, extruded through a T-die, and obtained a 2.0 mm thick sheet material by calendering rolls, thus obtaining a resin sheet.

[0194] The optical properties of the resin sheet obtained in Comparative Example 2 were measured, and the visible light transmittance was 5.2%, the transmittance at a wavelength of 905 nm was 13.4%, and the transmittance at a wavelength of 1550 nm was 34.1%. The measurement results are shown in Table 1. The obtained transmittance curve is shown in Figure 5.

[0195] [Table 1] 3. Evaluation of the Examples and Comparative Examples In Examples 1 to 3 and Example 5, a resin sheet containing infrared-transmitting material particles according to one embodiment of the present disclosure was manufactured, and it can be confirmed that the transmittance of visible light in region 51 shown in Figure 5 is sufficiently lower compared to the resin sheet of Comparative Example 1. Furthermore, in the resin sheets of Examples 1 to 3 and Example 5, it can be confirmed that the transmittance at at least one of the wavelengths selected from the dotted line 52 (905 nm) and the dotted line 53 (1550 nm) in Figure 5 exceeds 50%, which is higher than that of the resin sheet of Comparative Example 2. Light at wavelengths of 905 nm and 1550 nm are in the infrared region, which is mainly used in infrared sensors and the like.

[0196] In other words, the resin sheets of Examples 1 to 3 blocked visible light and maintained a low visible light transmittance of approximately 20% or less, while showing high transmittance of over 50% in infrared light at wavelengths of 905 nm and 1550 nm.

[0197] Although the transmittance curve is not shown in Figure 5, as shown in Table 1, it has been confirmed that the resin sheet of Example 4 and the infrared-transmitting laminated structure of Example 6 also exhibit the same characteristics.

[0198] In Example 5, a resin sheet containing appropriate infrared-transmitting material particles in addition to the infrared-transmitting material particles according to one embodiment of the present disclosure was manufactured, resulting in high transmittance for infrared light at a wavelength of 1550 nm while blocking visible light and infrared light at a wavelength of 905 nm.

[0199] In contrast to these evaluation results, the resin sheet of Comparative Example 1 did not contain infrared-transmitting material particles according to one aspect of this disclosure. Therefore, although it had high transmittance in infrared light at wavelengths of 905 nm and 1550 nm, it did not have the function of blocking visible light.

[0200] In Comparative Example 2, instead of the infrared-transmitting material particles according to one embodiment of the present disclosure, a resin sheet containing carbon black particles, which are typically used as a black pigment, was prepared. As a result, although the resin sheet of Comparative Example 2 could block light in the visible light region and exhibit low visible light transmittance, the carbon black particles also absorbed infrared light, resulting in low transmittance of infrared light at wavelengths of 905 nm and 1550 nm. [Explanation of Symbols]

[0201] 10 Infrared transmitting material particle dispersion 11 Infrared-transmitting material particles 12 Liquid media 20 Infrared transmitting material particle dispersion 21 Infrared-transmitting material particles 22 Solid medium 30 Infrared-transmitting laminate 311 Transparent base material 312 Transparent base material 32 Infrared transmitting material particle dispersion 40 Infrared-transmitting substrate 41 Base material 41A One side 42 Infrared-transmitting layer 51 areas 52 dotted lines 53 dotted line

Claims

1. Composition formula: A ｘ Bi ｙ O ｚ It contains a complex bismuth oxide represented by, In the above compositional formula, element A is one or more elements selected from calcium, strontium, and barium, Bi is bismuth, and O is oxygen. The above compositional formula comprises infrared-transmitting material particles where x, y, and z satisfy the relationships 2.5 ≤ z / y ≤ 4.0 and 0.6 ≤ x / y ≤ 1.

8.

2. The infrared-transmitting material particles according to claim 1, wherein the volume-average particle diameter is 1 nm or more and 800 nm or less.

3. The infrared-transmitting material particle according to claim 1, wherein x, y, and z in the composition formula satisfy the relationships 2.9 ≤ z / y ≤ 3.1 and 0.9 ≤ x / y ≤ 1.

1.

4. The infrared-transmitting material particles according to claim 1, wherein the composite bismuth oxide has one or more crystal structures selected from cubic, tetragonal, orthorhombic, and monoclinic.

5. Liquid medium and A dispersion of infrared-transmitting material particles comprising infrared-transmitting material particles according to any one of claims 1 to 4, disposed in the liquid medium.

6. Solid media and An infrared-transmitting material particle dispersion comprising infrared-transmitting material particles according to any one of claims 1 to 4, disposed in the solid medium.

7. An infrared-transmitting material particle dispersion according to claim 6, having a sheet shape, a board shape, or a film shape.

8. The content of the infrared-transmitting material particles per unit area is 0.3 g / m². ２ 4.0g / m or more ２ The infrared-transmitting material particle dispersion according to claim 6 is as follows:

9. The infrared-transmitting material particle dispersion according to claim 6, further comprising infrared-absorbing particles.

10. The infrared-transmitting material particle dispersion according to claim 9, wherein the infrared-absorbing particles contain hexaboride.

11. The infrared-transmitting material particle dispersion according to claim 10, wherein the hexaboride is lanthanum hexaboride.

12. Multiple transparent substrates, An infrared-transmitting laminate comprising an infrared-transmitting material particle dispersion according to claim 6, disposed between a plurality of transparent substrates.

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