Light-absorbing material and composition including same

Abstract

The purpose of the present invention is to provide a novel light-absorbing material. The purpose of the present invention is to provide a novel light-absorbing material capable of exhibiting light absorption performance typically over a wider wavelength range. A light-absorbing material according to the present disclosure is characterized by including a silicon oxynitride-based composition represented by the compositional formula SixAlwOyNz (where x, y, and z are independent positive real numbers that are not 0, and w is an independent positive real number including 0), and further including at least one type of element different from the silicon oxynitride-based composition, the integrated value of the KM value obtained by Kubelka-Munk conversion (KM conversion) from a wavelength of 600 nm to a wavelength of 2400 nm being 700 or more when the reflection spectrum of a powder of the light-absorbing material in the ultraviolet to near-infrared region is measured by a diffuse reflection method.

Description

Light-absorbing material and composition containing the same

[0001] The present invention relates to light-absorbing materials and compositions containing the same.

[0002] Currently, there is a growing need for light-shielding technology, i.e., materials that absorb light in specific wavelength ranges, in a variety of applications. For example, ultraviolet and infrared absorbing glass is known as a material that can absorb infrared rays that are contained in external light sources such as sunlight and light bulbs and become heat components, as well as ultraviolet rays that are harmful to the skin, etc. (Patent Document 1).

[0003] Furthermore, inorganic compound-based ultraviolet and infrared absorbing materials have been proposed that not only absorb light but also have solvent resistance such as alkali resistance, moisture resistance, heat resistance, heat ray blocking performance, etc. (Patent Documents 2 to 5). Furthermore, in order to address the issue of using expensive and toxic metal elements, an infrared absorbing material containing iron element in alumina has been proposed from the perspective of being cheaper and emphasizing safety (Patent Document 6).

[0004] Meanwhile, silicon oxynitride-based materials have been attracting attention as materials that combine excellent heat resistance, abrasion resistance, corrosion resistance, and other properties with industrial productivity and safety, as they can be obtained by firing at relatively low temperatures (Patent Documents 7 and 8). SIALON-based materials have also been attracting attention as materials that require low reflectivity for applications such as optical components (Patent Documents 9 and 10).

[0005] Patent Document 1: JP 2013-209224 A Patent Document 2: JP 2023-034390 A Patent Document 3: JP 2013-087228 A Patent Document 4: JP 2001-262064 A Patent Document 5: JP 2000-319554 A Patent Document 6: JP 2015-127809 A Patent Document 7: JP 10-158003 A Patent Document 8: WO 2023 / 136349 Patent Document 9: JP 2007-238430 A Patent Document 10: JP 06-172034 A

[0006] The above patent documents discuss various materials. However, the optical properties of these materials, such as light absorption, transmittance, and reflectance, are limited to a relatively limited wavelength range. Specifically, the light absorption properties in Patent Document 1 are for a light source with a dominant wavelength of 510 to 560 nm. Patent Document 2 discloses absorbance at 500 nm and 1300 nm. Patent Documents 3 and 4 disclose suppression (blocking) of transmission in the ultraviolet and / or near-infrared range, but not suppression (blocking) of transmission in the visible range. Patent Document 5 discusses minimal transmittance in the 700 to 1800 nm range, while Patent Document 6 discusses spectral transmittance in the 300 to 2000 nm range. Patent Document 7 does not discuss optical properties. Patent Document 8 discusses light transmittance in the 2000 to 2500 nm or 400 to 700 nm range. Patent Document 9 discloses reflectance in the visible range of 380 to 800 nm. The reflectance in Patent Document 10 is for wavelengths between 350 and 800 nm.

[0007] However, there is room for further investigation into the optical properties over a wider wavelength range, meaning that further material development is required.

[0008] Therefore, an object of the present invention is to provide a novel light-absorbing material, typically a novel light-absorbing material that can exhibit light-absorbing performance over a wider wavelength range.

[0009] As a result of extensive research, the inventors discovered that when a silicon oxynitride-based material contains a different element, it exhibits a previously unknown light absorption ability, more specifically, a high light absorption ability over a wide wavelength range, and this discovery led to the idea for the present invention.

[0010] The present invention provides the following aspects.

[0011] [1] A light-absorbing material comprising a silicon oxynitride-based composition represented by the composition formula SixAlwOyNz, wherein x, y, and z are each independently a positive real number other than 0, and w is an independent positive real number including 0, and further comprising at least one element different from said silicon oxynitride-based composition, characterized in that, when a reflectance spectrum of a powder of said light-absorbing material in the ultraviolet to near-infrared region is measured by a diffuse reflectance method, the integrated value of the K.M. value obtained by the Kubelka-Munk transformation, i.e., K.M. transformation, from a wavelength of 600 nm to a wavelength of 2400 nm is 700 or more.

[0012] [2] The light-absorbing material according to [1], comprising a silicon oxynitride-based composition represented by the composition formula SixAlwOyNz, wherein x, y, and z are each independently a positive real number other than 0, and w is an independent positive real number including 0, and further comprising at least one element different from the silicon oxynitride-based composition, wherein the light-absorbing material has a K.M. value of 0.4 or more at a wavelength of 1800 nm.

[0013] [3] The light-absorbing material according to [1] or [2], wherein the different element is selected from the group consisting of Fe, Cu, Cr, Co, Ti, Ni, Mn, and Zr.

[0014] [4] The light-absorbing material according to any one of [1] to [3], wherein the different element is Fe.

[0015] [5] The light-absorbing material according to any one of [1] to [4], characterized in that the content of the different element is 0.002 mass % or more and 10.0 mass % or less.

[0016] [6] A composition comprising the light-absorbing material according to any one of [1] to [5].

[0017] According to the present disclosure, a novel light-absorbing material and a composition containing the same are provided. The light-absorbing material can exhibit light absorption performance over a relatively wide wavelength range. The absorbing material contains a silicon oxynitride composition as a base, can have high thermal stability, and can have a high degree of freedom in material form, and can be provided in various forms such as powder, slurry, film, sheet, and grease. The absorbing material can contain a different element and exhibit a coloring effect due to the different element.

[0018] FIG. 1 is a schematic side view of the device configuration for the light irradiation and temperature rising test. FIG. 2 is an enlarged side view of a test piece and a reference piece. FIG. 3 is a schematic top view of the device configuration for the light irradiation and temperature rising test. FIG. 4 is a diagram showing an example of structure measurement by X-ray diffraction (XRD). FIG. 5 is a diagram showing an example of structure measurement by X-ray diffraction (XRD).

[0019] Hereinafter, one embodiment of the present invention will be described in detail, but the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Furthermore, when multiple upper and lower limit values ​​are specified for a specific parameter, any upper and lower limit values ​​can be combined to form a suitable numerical range.

[0020] One embodiment of the present invention, a light-absorbing material, comprises a silicon oxynitride-based composition represented by the formula SixAlwOyNz (where x, y, and z are each independently a positive real number that is not 0, and w is an independent positive real number that includes 0).

[0021] (Silicon oxynitride composition) The silicon oxynitride composition can contain silicon (Si), aluminum (Al), oxygen (O), and nitrogen (N) as constituent elements. The composition ratio (or molar ratio) of each constituent element is represented by x, w, y, and z. That is, the composition ratio of silicon (Si) is x, that of aluminum (Al), that of oxygen (O), and that of nitrogen (N) is z. Here, x, y, and z are each independent positive real numbers other than 0, and w is an independent positive real number including 0. Therefore, the silicon oxynitride composition is a composition containing silicon (Si), oxygen (O), and nitrogen (N) as essential constituent elements, and when X-ray diffraction analysis (XRD) is performed, the peak positions observed are those of silicon oxynitride (Si ２ N ２ The peak position may overlap with that observed for silicon oxynitride (Si). Furthermore, the silicon oxynitride-based composition may contain aluminum (Al), and may include a sialon-based composition. The sialon-based composition is a composition containing silicon (Si), aluminum (Al), oxygen (O), and nitrogen (N) as essential constituent elements, and is sometimes referred to as sialon. In particular, silicon oxynitride (Si ２ N ２ A silicon oxynitride (Si) composition in which some of the silicon (Si) atoms are replaced with aluminum (Al) atoms and some of the nitrogen (N) atoms are replaced with oxygen (O) atoms is called O'-sialon. Sialon exhibits superior heat resistance, mechanical strength in high-temperature environments, thermal shock resistance, and wear resistance to silicon oxynitride. Silicon oxynitride compositions that do not contain aluminum (Al) are sometimes called Sion.

[0022] The silicon oxynitride composition is primarily composed of SiON and / or SIALON. Typically, the SiON and / or SIALON content is 50% by mass or more based on 100% by mass of the solids content of the silicon oxynitride composition. A higher SiON and / or SIALON content is preferable because it facilitates the attainment of properties derived from SiON and / or SIALON. From this perspective, the SiON content is preferably 65% ​​by mass or more, and more preferably 85% by mass or more. The upper limit of the SiON content is not particularly limited and may be 100% by mass, 99%, 98%, 97%, 96%, 95%, or 94% by mass.

[0023] Silicon oxynitride-based compositions may contain any component other than SION and / or SIALON, typically SiO, SiO ２ and / or Si ３ N ４ The silicon oxynitride composition may contain, for example, silicon dioxide. However, as the content of these optional components increases, the content of SiON and / or SIALON decreases, making it difficult to obtain the properties derived from SiON and / or SIALON. Therefore, the content of the optional components is preferably less than 50% by mass, more preferably less than 35% by mass, and even more preferably less than 15% by mass, based on 100% by mass of the solids content of the silicon oxynitride composition. The lower limit of the content of the optional components is not particularly limited, and may be 0% by mass, 1%, 2%, 3%, 4%, 5%, or 6% by mass.

[0024] The composition ratio (or molar ratio) of each element constituting the silicon oxynitride composition is measured by inductively coupled plasma atomic emission spectrometry. However, the oxygen (O) content is measured by an oxygen quantification method using an inert gas fusion-infrared absorption method in accordance with JIS R1603:2007. The nitrogen (N) content is measured by an nitrogen quantification method using an inert gas fusion-thermal conduction method in accordance with JIS R1603:2007. The structure of the silicon oxynitride composition can also be estimated by observing it using X-ray diffraction analysis (XRD).

[0025] The light-absorbing material, which is one embodiment of the present invention, contains at least one element different from the silicon oxynitride-based composition.

[0026] (Heterogeneous element) The heterogeneous element is an element different from the constituent elements contained in the silicon oxynitride composition, i.e., silicon (Si), aluminum (Al), oxygen (O), and nitrogen (N). The light-absorbing material of this embodiment contains a silicon oxynitride composition and a heterogeneous element, and thereby can exhibit light absorption different from the light absorption obtained by the silicon oxynitride composition alone. Typically, it is possible to exhibit light absorption over a wide wavelength range. The type of heterogeneous element may be appropriately selected depending on the desired light absorption.

[0027] Although we do not wish to be bound by any particular theory, it is believed that in silicon oxynitride-based compositions, different elements can exist in a variety of states with different absorption wavelengths, which changes the optical properties of the silicon oxynitride-based composition itself, making it possible for the composition to exhibit light absorption properties over a wide wavelength range.

[0028] The hetero element is not particularly limited as long as it acts to provide light absorption and does not interfere with the effects of the present invention. As described above, the type of hetero element may be appropriately selected depending on the desired light absorption. Such hetero elements are transition elements. Typically, one or more hetero elements may be selected from Fe, Cu, Cr, Co, Ti, Ni, Mn, and Zr, or two or more may be selected. These hetero elements are transition elements and affect the coloration of materials containing these hetero elements through actions such as charge transfer. In other words, the inclusion of these hetero elements makes it possible to adjust the coloration of the light-absorbing material. Among these hetero elements, Fe may be selected. Fe is preferred because of its low procurement cost, ease of availability, and ease of handling. Furthermore, it is also preferred to use a material containing multiple hetero elements, such as stainless steel, as a raw material from the perspective of ease of availability and handling. The hetero elements may be added from the outside, or component elements contained in the raw material used may be used.

[0029] The content of the different elements is not particularly limited as long as it does not interfere with the effects of the present invention. The content of the different elements may be adjusted appropriately depending on the desired light absorption properties, coloring effect, etc. Typically, the content of the different elements may be 0.002 mass% or more and 10.0 mass% or less, based on the light-absorbing material (100 mass%). If the content of the different elements is less than 0.002 mass%, the desired effect may not be obtained. Therefore, the lower limit of the content of the different elements may be appropriately selected, and may be 0.002 mass% or more, 0.003 mass% or more, 0.005 mass% or more, 0.007 mass% or more, 0.010 mass% or more, 0.030 mass% or more, 0.050 mass% or more, 0.070 mass% or more, 0.100 mass% or more, 0.200 mass% or more, 0.300 mass% or more, 0.400 mass% or more, 0.500 mass% or more, 1.000 mass% or more, 2.000 mass% or more, or 3.000 mass% or more. On the other hand, if the content of the different elements exceeds 10.0 mass%, the effects provided by the different elements may saturate. Furthermore, the content of the silicon oxynitride-based composition may decrease relatively, and the effects provided by the silicon oxynitride-based composition may decrease. Therefore, the upper limit of the content of the different elements may be selected as appropriate, and may be 10.0 mass% or less, 9.0 mass% or less, 7.0 mass% or less, 5.0 mass% or less, 4.0 mass% or less, 3.8 mass% or less, or 3.0 mass% or less.

[0030] The content of the different elements is measured by inductively coupled plasma atomic emission spectrometry, in the same manner as the content of each constituent element of the silicon oxynitride composition.

[0031] In one embodiment of the present invention, the light-absorbing material has a powder of the material whose reflectance spectrum in the ultraviolet to near-infrared region is measured using a diffuse reflectance method, and the integral of the K.M. value obtained from a wavelength of 600 nm to 2400 nm using the Kubelka-Munk transformation (also referred to as the K.M. transformation) is 700 or more. Here, the integral is the sum of all the K.M. values ​​measured at wavelengths of 1 nm each. To enhance the light-shielding effect and the temperature-raising effect due to light absorption, the integral is preferably 800 or more, 900 or more, 950 or more, 980 or more, and even more preferably 1000 or more. The upper limit of the integral is not particularly limited, and may typically be 4000 or less, 3700 or less, 3600 or less, 3500 or less, 3400 or less, 3300 or less, 3000 or less, 2500 or less, 2400 or less, 2200 or less, or 2100 or less. The range of the integral is not particularly limited as long as it is 700 or more, and may be a combination of the above-mentioned lower and upper limits. Typically, the range of the integral may be 700 or more and 3700 or less, 900 or more and 3700 or less, 1400 or more and 3700 or less, 2000 or more and 3700 or less, 900 or more and 2500 or less, or 1400 or more and 2100 or less.

[0032] (K.M. Value Obtained by Kubelka-Munk Transformation (K.M. Transformation)) For a powder sample, the K.M. value of the sample can be calculated by performing Kubelka-Munk Transformation (K.M. Transformation) on the spectrum obtained by measuring the diffuse reflectance of the sample.

[0033] Alternatively, the light-absorbing material according to one embodiment of the present invention preferably has a K.M. value obtained by Kubelka-Munk transformation (K.M. transformation) of 0.4 or more at a wavelength of 1800 nm. This is because the wavelength of 1800 nm is a typical wavelength range in which infrared light has high biological transmittance but cannot be fully absorbed by conventional infrared absorbing materials, particularly light-absorbing materials based on organic materials with high versatility. In this respect, the K.M. value at 1800 nm is more preferably 0.5 or more, and the K.M. value at 1800 nm is even more preferably 0.6 or more, 0.8 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.5 or more. The upper limit of the K.M. value at 1800 nm is not particularly limited, and may typically be 4.0 or less, 3.7 or less, 3.5 or less, 3.0 or less, 2.5 or less, 2.4 or less, 2.1 or less, or 2.0 or less. The K.M. value at 1800 nm is more preferably 0.5 or more, and even more preferably 0.6 or more, 0.8 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.5 or more. The upper limit of the K.M. value at 1800 nm is not particularly limited, and may typically be 4.0 or less, 3.7 or less, 3.5 or less, 3.0 or less, 2.5 or less, 2.4 or less, 2.1 or less, or 2.0 or less. The K.M. value range is preferably 0.4 or more, and may be a combination of the above-mentioned lower and upper limits. Typically, the K.M. value at 1800 nm may be in the range of 0.4 to 4.0, 0.6 to 2.4, 0.6 to 2.1, 0.8 to 2.4, 1.1 to 2.4, 1.5 to 2.4, or 1.3 to 2.1.

[0034] That is, the light-absorbing material according to one embodiment of the present invention exhibits light absorption over a wide wavelength range from the visible light region to the infrared region. Typically, when a composition containing the light-absorbing material according to this embodiment is irradiated with light having a wavelength from the visible light region to the infrared region, the temperature rise can be faster and the final temperature can be higher than that of a composition not containing the light-absorbing material. In particular, the light-absorbing material according to one embodiment of the present invention has a high K.M. value at a specific wavelength in the infrared region and is therefore likely to absorb light having a wavelength in the infrared region.

[0035] (Method for Producing Light-Absorbing Material) The light-absorbing material according to one embodiment of the present invention may be produced by any method without particular limitation. Typically, the light-absorbing material can be produced as follows: Raw materials are mixed to a desired composition ratio so as to obtain a silicon oxynitride-based composition contained in the light-absorbing material. Separately, different elements contained in the light-absorbing material are mixed with the silicon oxynitride composition to obtain a desired content. Alternatively, different elements may be mixed into a mixture of raw materials to obtain a silicon oxynitride-based composition. The mixture may also be subjected to appropriate treatments such as drying, pulverization, heating, cooling, pressurization, and decompression. The silicon oxynitride-based composition of the present invention can be obtained by heating and firing the resulting raw material mixture under conditions such as those described in, for example, JP 2021-34587 A, typically at about 1400 to 1600°C in a nitrogen atmosphere for several hours. The resulting fired product may also be subjected to appropriate treatments such as drying, pulverization, heating, cooling, pressurization, and decompression.

[0036] In one embodiment of the present invention, a composition is provided, the composition comprising the light-absorbing material according to one embodiment of the present invention described above. The composition may be a resin composition comprising a resin.

[0037] The form of a composition comprising a light-absorbing material, which is one embodiment of the present invention, is not limited as long as it does not interfere with the effects of the present invention. Typically, the composition may be an amorphous solid such as a powder or granules, or may be a solid having a regular shape such as a lump, pellet, film, plate, etc. Furthermore, the form of the light-absorbing material itself is also not limited. Typically, the light-absorbing material may be an amorphous solid such as a powder or granules, or may be a solid having a regular shape such as a lump, pellet, film, plate, etc.

[0038] The composition may be a liquid such as a slurry, grease, or paint. Examples of solvents for these liquids include water and organic solvents. Examples of organic solvents that can be used include alcohols such as methanol, ethanol, and isobutyl alcohol; ether alcohols such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; esters such as methyl acetate and ethyl acetate; and ketones such as methyl ethyl ketone and cyclohexanone. Depending on the application, one or more solvents may be used in combination. The liquid may contain an acid, and examples of the acid that can be used include mineral acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid.

[0039] <Additives> Furthermore, the composition may contain the following additives as optional components within the range that does not significantly impair the effects of the present invention. Examples of additives that can be used in the composition include inorganic compounds (aluminum oxide (Al ２ O ３ ), zirconium oxide (ZrO ２ ), hafnium oxide (HfO ２ ), magnesium oxide (MgO), titanium oxide (TiO ２ ), vanadium oxide (VO ２ , V ２ O ５ ), boron oxide (BO ３The heat-shielding and light-shielding substrate may contain, as appropriate, known additives for heat-shielding and light-shielding substrates, such as oxides (metal oxides and non-metal oxides) such as talc and kaolin; alkali metal salts such as sodium carbonate, potassium carbonate, cesium carbonate, potassium chloride, sodium chloride, potassium bromide, potassium iodide, sodium iodide, potassium sulfate, and sodium sulfate; alkaline earth metal salts such as calcium carbonate, magnesium carbonate, calcium chloride, magnesium chloride, barium sulfate, and magnesium sulfate; and phosphates such as magnesium hydrogen phosphate and magnesium hydrogen phosphate), light stabilizers, antioxidants, antiaging agents, heat stabilizers, colorants (e.g., pigments and dyes), lubricants, fillers, antistatic agents, slip agents, antiblocking agents, fibrous reinforcements, particulate reinforcements, plasticizers, foaming agents, weather resistance agents, crystal nucleating agents, crystallization accelerators, release agents, flame retardants, and flame retardant assistants. These additives may be commercially available products or separately synthesized preparations. Furthermore, commercially available products or prepared products may be used after processing such as granulation (aggregation, pulverization) and the like.

[0040] The present invention will be specifically described below with reference to examples, although the present invention is not limited to the following examples.

[0041] Sample powders of light-absorbing materials were prepared under the following various conditions.

[0042] <SION System> <Example 1> 62 g of tetraethyl orthosilicate (FUJIFILM Wako Pure Chemical Corporation), 5 g of iron chloride (FUJIFILM Wako Pure Chemical Corporation), 50 g of water, and 53 g of ethanol were stirred at room temperature for 1 hour. Precipitation was performed with aqueous ammonia to obtain a solid, which was then washed with distilled water and then ethanol. The solid was dried to obtain silica gel containing 0.82% by mass of Fe. 2.1 g of the obtained silica gel, 2.9 g of metal silicon powder (Kojundo Chemical Laboratory Co., Ltd.), and 20 g of ethanol were mixed in a ball mill using alumina balls for 6 hours and then dried under reduced pressure at 60°C for 6 hours to obtain a mixture. The resulting mixture was fired at 1500°C in a nitrogen atmosphere (nitrogen flow rate 1 L / min) for 3 hours. The mixture was then cooled to room temperature in the nitrogen atmosphere over 12 hours to obtain a fired product. The fired product was then crushed in an agate mortar to obtain a sample powder.

[0043] Comparative Example 1 A silica gel was synthesized, calcined, and pulverized in the same manner as in Example 1, except that iron chloride was not used. The calcined product was then pulverized in the same manner as in Example 1 to obtain a sample powder.

[0044] Comparative Example 2: 6.0 g of metallic silicon powder (Kojundo Chemical Laboratory Co., Ltd.), 6.0 g of silicon dioxide powder (SiO ２ ) (High Purity Chemical Laboratory Co., Ltd.) 4.3 g was mixed in a ball mill using alumina balls for 6 hours to obtain a mixture. The obtained mixture was held in a nitrogen atmosphere (nitrogen flow rate 1 L / min) at a furnace temperature of 1500°C for 3 hours. Thereafter, it was cooled to room temperature over 12 hours while still in the nitrogen atmosphere to obtain a fired product. The fired product was pulverized in an agate mortar to obtain a sample powder.

[0045] <Example 2> Metallic silicon powder 6.0 g, silicon dioxide powder (SiO ２ ) 4.3 g, and iron trioxide (Fe ２ O ３ ) (FUJIFILM Wako Pure Chemical Corporation) was added, and the mixture was ball milled using alumina balls for 6 hours to obtain a mixture. The resulting mixture was maintained at a furnace temperature of 1500°C for 3 hours under a nitrogen atmosphere (nitrogen flow rate 1 L / min). After that, it was cooled to room temperature over 12 hours while still in the nitrogen atmosphere to obtain a fired product. The fired product was pulverized in an agate mortar to obtain a sample powder.

[0046] Example 3: Diiron trioxide (Fe ２ O ３ A fired product was prepared in the same manner as in Example 2, except that the amount of the powder was changed to 0.6 g, to obtain a sample powder.

[0047] Example 4: 106.3 g of metal silicon powder, 106.3 g of silicon dioxide powder (SiO containing 0.04 mass % of impurity Fe element) ２113.7 g of Fe was used and mixed in a ball mill using alumina balls for 6 hours to obtain a mixture. The obtained mixture was held in a nitrogen atmosphere (nitrogen flow rate 2 L / min) at a furnace temperature of 1425°C for 3 hours. It was then cooled to room temperature over 12 hours while still in the nitrogen atmosphere to obtain a fired product. The fired product was pulverized in an alumina mortar to obtain a sample powder. The fired product contained the metal elements Al, Ca, Mg, K, and Na in addition to Fe, and the total amount of these metal elements (excluding Fe) was 0.3 mass%.

[0048] Example 5: Diiron trioxide (Fe ２ O ３ A fired product was prepared in the same manner as in Example 4, except that an additional 17.6 g of Fe was added and mixed. The resulting sample contained 4.1 mass % of Fe element.

[0049] Example 6: SiO containing 0.01% by mass of Fe element ２ A sample powder was obtained in the same manner as in Example 2, except that the following was used.

[0050] <Example 7> 2.9 g of metal silicon powder, 2.9 g of silicon dioxide powder (SiO ２ ) 2.1 g, iron trioxide (Fe ２ O ３ 0.1 g of ammonium hydroxide and 20 g of ethanol were mixed in a ball mill using alumina balls for 6 hours. The resulting slurry was dried under reduced pressure at room temperature for 12 hours to obtain a mixture. The resulting mixture was kept at a furnace temperature of 1500°C for 3 hours in a nitrogen atmosphere (nitrogen flow rate 1 L / min). It was then cooled to room temperature over 12 hours while still in the nitrogen atmosphere to obtain a fired product. The fired product was pulverized in an agate mortar to obtain a sample powder.

[0051] Comparative Example 3: Fe ２ O ３ A sample powder was obtained in the same manner as in Example 7, except that no was added.

[0052] Example 9 A sample powder was obtained in the same manner as in Example 4, except that 106 g of metallic silicon and 114 g of silicon dioxide powder containing 0.03 mass % of Fe element as an impurity were used.

[0053] Example 10 A sample powder was obtained in the same manner as in Comparative Example 2, except that 0.2 g of stainless steel powder containing 67.5 mass %, 17.0 mass %, 13.0 mass %, and 2.5 mass % of Fe, Cr, Ni, and Mo, respectively, was added.

[0054] <SIALON system> <Example 8> 53 g of metal silicon powder, silicon dioxide powder (SiO ２ ) 38 g, aluminum oxide (Al ２ O ３ ) 14 g and iron trioxide (Fe ２ O ３ 1.8 g of the powder was mixed in a ball mill using alumina balls for 6 hours. The resulting mixture was held in a nitrogen atmosphere (nitrogen flow rate 1 L / min) at a furnace temperature of 1500°C for 3 hours. After that, it was cooled to room temperature over 12 hours while still in the nitrogen atmosphere to obtain a fired product. The fired product was pulverized in an alumina mortar to obtain a sample powder.

[0055] Comparative Example 4: Fe ２ O ３ A fired product was prepared in the same manner as in Example 8 except that no additive was added, and a sample powder was obtained.

[0056] Reference Examples 1 to 3 The heat-absorbing glasses listed in Table 1 were crushed in an agate mortar to prepare sample powders. Similarly, sample powders were prepared from silica powder. Glass (G) was green glass, and glass (B) was black glass. Elemental analysis of heat-absorbing glass (B) revealed that it contained 0.97% by mass of Al and 0.32% by mass of Fe. No Fe was detected in the silica powder.

[0057] The sample powders of the light-absorbing material produced above were subjected to elemental analysis and diffuse reflectance measurement in the following manner. In addition, some of the sample powders were subjected to a light irradiation temperature rise test and structural measurement by X-ray diffraction (XRD).

[0058] [Elemental Analysis] Quantitative analysis was performed under the following conditions to examine the elements in the samples. (1) Elements other than O and N: The sample and acid were placed in a decomposition vessel, heated and decomposed by microwave irradiation, and then the volume was adjusted to a constant level with ultrapure water to obtain a test solution. Elements detected at 10 μg / g or more were qualitatively analyzed using inductively coupled plasma atomic emission spectroscopy (instrument: Agilent Technologies ICP AES Agilent 5110 VDV model), and elements detected at 100 μg / g or more were quantitatively analyzed. In addition to the elements listed in Table 2, Cr, Ni, Ca, Cu, K, Mn, Mo, Na, Ti, and other elements were detected in each example and comparative example. (2) O and N Elements: Using a LECO TCH600 model, O was measured by inert gas fusion-infrared absorption spectroscopy, and N was measured by inert gas fusion-thermal conductivity spectroscopy.

[0059] [Measurement of diffuse reflectance of ultraviolet, visible, and near-infrared light] The obtained sample powder was filled into a measurement holder, and diffuse reflectance was measured under the following conditions. Kubelka-Munk transformation (K.M. transformation) was performed to obtain K.M. values. The results are shown in Tables 1 and 2. Model: Spectrophotometer V-770 manufactured by JASCO Corporation, integrating sphere unit ISN-923 model Measurement wavelength: 200 to 2500 nm Bandwidth: UV / VIS 5.0 nm, NIR 20.0 nm Response: 0.96 sec Data acquisition: 1 nm Scanning speed: 1000 nm / min Standard white board: A Spectralon reflectance measurement adapter manufactured by Labsphere was installed for measurement (specular reflection light was removed)

[0060]

[0061]

[0062] [Light Irradiation Temperature Rise Test] (Preparation of Test Pieces) For each of the samples of Examples 4, 6, and 10, Comparative Example 2, and Reference Example 3, 0.65 g of sample powder was mixed with 45 g of liquid acrylic adhesive (woodworking bond) to prepare a slurry. This was applied to a metal substrate 7 measuring 200 mm in length, 300 mm in width, and 0.5 mm in thickness at a thickness of 0.15 mm. After drying and curing in an oven at 60°C for 30 minutes, a test piece 1 for the light irradiation temperature rise test was obtained, having a coating film layer measuring 110 mm in length and 60 mm in width. A reference piece 1' was obtained in the same manner as above, using liquid acrylic adhesive (woodworking bond) without mixing the sample powder.

[0063] (Light Irradiation Temperature Rise Test) Test piece 1 and reference piece 1' were placed on a paper sample stage 3 of the light irradiation temperature rise test apparatus shown in Figure 1, and a light irradiation temperature rise test was conducted. The temperature rise measurement due to light irradiation was conducted using the apparatus configuration shown in Figure 1, in which a 100W incandescent lamp 2 was placed 30 cm above the test piece and a thermocouple 4 was attached below the test piece. The temperature on the back side of the sample 15 minutes after the start of light irradiation was measured with the thermocouple. Three measurements were conducted, and the average value was used as the sample temperature during light irradiation. Figure 1 is a side view of the apparatus configuration, and Figure 3 is a top view of the apparatus configuration. Figure 2 is an enlarged side view of test piece 1 and reference piece 1'. The test results are shown in Table 3. In the examples of the present invention, test piece 1, which used a silicon oxynitride-based light-absorbing material, rose in temperature more quickly and reached a higher temperature than reference piece 1', which served as a control. In the comparative examples and reference examples, no significant differences were observed between test piece 1 and reference piece 1'.

[0064]

[0065] [Structural Measurement by X-ray Diffraction (XRD)] The sample powders of Examples 2, 8, and Comparative Example 2 were placed in a measurement holder and measured under the following conditions. The results are shown in Figures 4 and 5. Model: Wide-angle X-ray diffractometer RINT-TTIII model manufactured by Rigaku Corporation X-ray source: CuKα radiation, tube voltage-tube current: 50 kV-300 mA Optical system: Diffraction line curved crystal monochromator Scanning range: 5-80° Step width: 0.02° Measurement speed: 2° / min

[0066] 4 and 5, in all of the powders of Example 2 (SION type), Example 8 (SIALON type), and Comparative Example 2 (SION type without containing any other element), Si ２ N ２ A peak of O or O'-sialon was confirmed. This suggests that the structure of the silicon oxynitride-based composition is not significantly changed by the different elements contained in the light-absorbing material, in other words, that the different elements are present at the grain boundaries of the silicon oxynitride-based composition.

[0067] REFERENCE SIGNS LIST 1 Test piece 1' Reference piece 2 Light bulb 3 Paper sample stand 4 Thermocouple 5 Temperature recorder 6 Coating film 7 Metal substrate

Claims

1. A light-absorbing material comprising a silicon oxynitride-based composition represented by the composition formula SixAlwOyNz, wherein x, y, and z are each independently a non-zero positive real number, and w is an independent positive real number including 0, and further comprising at least one element heterogeneous with respect to said silicon oxynitride-based composition, characterized in that, when the reflectance spectrum of a powder of said light-absorbing material in the ultraviolet to near-infrared region is measured by a diffuse reflectance method, the integrated value of the K.M. value obtained by the Kubelka-Munk transformation, i.e., K.M. transformation, from a wavelength of 600 nm to a wavelength of 2400 nm is 700 or more.

2. A light-absorbing material according to claim 1, comprising a silicon oxynitride-based composition represented by the composition formula SixAlwOyNz, where x, y, and z are each independently a non-zero positive real number, and w is an independent positive real number including 0, and further comprising at least one element different from said silicon oxynitride-based composition, wherein the light-absorbing material has a K.M. value of 0.4 or greater at a wavelength of 1800 nm.

3. The light-absorbing material according to claim 1, wherein the different element is selected from the group consisting of Fe, Cu, Cr, Co, Ti, Ni, Mn, and Zr.

4. The light-absorbing material according to claim 1, wherein the different element is Fe.

5. The light-absorbing material according to claim 1, wherein the content of the different element is 0.002% by mass or more and 10.0% by mass or less.

6. A composition comprising the light-absorbing material according to any one of claims 1 to 5.

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