HEAT-INSULATING MATERIAL

Abstract

This heat-insulating material comprises: a porous structure in which a plurality of particles are bonded to form a skeleton and which has pores in the skeleton; infrared ray shielding particles; and hollow organic particles. When the mass of the heat-insulating material is specified as 100 mass%, the content of the infrared ray shielding particles in the heat-insulating material is 10 to 30 mass%. When the mass of the heat-insulating material is specified as 100 mass%, the content of the hollow organic particles is 5 to 30 mass%. The heat-insulating material exhibits excellent heat-insulating properties even at high temperatures and has excellent flexibility and compression recovery.

Description

Technical area

[0001] The disclosure relates to a thermally insulating material that utilizes a porous structure, such as an aerogel. State of the art

[0002] Conventionally, various heat-insulating materials have been used for heat flow control in automotive parts, building construction materials, industrial equipment, and the like. Materials with low thermal conductivity, such as silica aerogel, are known as heat-insulating materials. For example, in battery packs mounted in hybrid vehicles or electric vehicles, heat-insulating materials are interposed between adjacent battery cells, etc. This type of heat-insulating material is required to have excellent heat insulation properties, particularly at high temperatures, so that it can prevent heat transfer and thermal runaway in the event of a battery cell abnormally generating heat.Furthermore, in a battery pack, a battery module formed by laminating a plurality of battery cells is housed in a case in a state where it is fixed by fasteners from two sides in the lamination direction. During charging and discharging, battery cells expand and contract. Therefore, it is preferable that the heat-insulating material disposed between battery cells can deform in response to external pressure or expansion and contraction of the battery cells while maintaining its heat-insulating property.

[0003] For example, Patent Document 1 describes an aerogel composite containing aerogel components and hollow silica particles as an aerogel composite with thermal insulation properties and flexibility. Patent Document 2 describes a product comprising nanoporous particles and hollow latex particles, wherein the hollow latex particles are directly bonded to each other to form a continuous matrix, and the nanoporous particles are dispersed in the continuous matrix of the hollow latex particles. Document listPatent documents Patent Document 1: International Publication No. 2017 / 038646. Patent Document 2: Japanese translation of PCT International Application No. 2013-543036. SUMMARY OF THE INVENTIONTechnical Problem

[0004] According to the aerogel composite described in Patent Document 1 above, flexibility is improved by adding hollow silica particles to the aerogel component. However, hollow silica particles are made of a rigid inorganic material despite having a hollow structure. Consequently, the obtained flexibility is insufficient. Furthermore, according to Patent Document 1, flexibility is imparted to the aerogel merely for the purpose of improving the handleability of the aerogel. Therefore, even if the aerogel composite can be compressed and deformed by, for example, external pressure, the aerogel composite cannot be said to have the resilience to return to its original shape after release. Furthermore, Patent Document 1 does not consider a high-temperature thermal insulation property.

[0005] On the other hand, the hollow latex particles described in Patent Document 2 are made of a polymer and serve as a binder that binds nanoporous particles together. As described in Patent Document 2, the hollow latex particles are directly bonded to each other to form a continuous network structure (matrix), and the nanoporous particles are dispersed in the continuous matrix of hollow latex particles. Consequently, in the product described in Patent Document 2, the continuous hollow latex particles become a heat transfer path, leading to a deterioration in thermal insulation properties. Furthermore, when this product is used at high temperatures, there is a risk that the matrix may decompose, deteriorate, or disappear, causing its shape to be lost.Furthermore, paragraph

[0044] of Patent Document 2 states that "the concentration of additional additives such as infrared attenuators and reflective particles is 5% by mass or less based on the total weight of the product." Even if infrared ray shielding particles are added as an additional additive, a small amount of 5% by mass or less of the entire product will not be effective in blocking radiant heat, and the heat insulating property at high temperatures will be insufficient.

[0006] The disclosure has been provided in view of these circumstances and aims to provide a heat-insulating material utilizing a porous structure, having very good heat-insulating property even at high temperatures, and having excellent flexibility and recovery against compression. Solution to the problem

[0007] (1) To solve the above problem, the heat-insulating material of the disclosure is a heat-insulating material comprising a porous structure in which a plurality of particles are connected to form skeletons and which has pores between the skeletons, infrared ray shielding particles, and hollow organic particles, wherein the infrared ray shielding particles have a content of 10 mass% or more and 30 mass% or less when a mass of the heat-insulating material is 100 mass%, and the hollow organic particles have a content of 5 mass% or more and 30 mass% or less when a mass of the heat-insulating material is 100 mass%.

[0008] Due to the porous structure, a very good thermal insulation effect can be achieved primarily by preventing conduction and convection of the three forms of heat transfer (conduction, convection, and radiation). Radiation is a phenomenon in which heat moves through electromagnetic waves, and the higher the temperature, the greater the emitted radiant energy. Therefore, in high-temperature environments, radiation becomes the main factor in heat transfer. Consequently, at high temperatures, it is difficult to achieve the desired thermal insulation properties with a porous structure alone, and it becomes effective to use infrared ray shielding particles that can prevent heat transfer by radiation.However, in the case where a large amount of infrared ray shielding particles is mixed, the infrared ray shielding particles bond together to form a heat transfer path, which may lead to increased conductive heat transfer and deterioration of the heat insulating property. According to the heat insulating material of the disclosure, by controlling the content of infrared ray shielding particles, both radiation and conductive heat transfer can be prevented, thereby realizing excellent heat insulating properties not only at room temperature but also at high temperatures of 500°C or higher.

[0009] The heat-insulating material of the disclosure includes hollow organic particles in addition to infrared-ray shielding particles. Hollow organic particles are particles formed from an organic material and having voids inside. The hollow organic particles provide flexibility, allowing deformation against compressive loads and recovery after unloading. The hollow organic particles are arranged between porous inorganic particles and porous inorganic particles. In the heat-insulating material of the disclosure, since the content of hollow organic particles is relatively low, the hollow organic particles do not easily bond to each other, and many of the hollow organic particles are arranged discontinuously.Consequently, in the heat-insulating material of the disclosure, the porous structure forms a matrix, and the hollow organic particles are distributed among the porous structures. Consequently, even though the heat-insulating material of the disclosure contains hollow organic particles, which are organic components, heat transfer paths are not easily formed. As a result, the hollow organic particles do not easily disappear even at high temperatures, and excellent heat-insulating properties can be maintained.

[0010] (2) In the above configuration, the porous structure may have an average particle diameter of 1 μm or more and 1000 μm or less. According to this configuration, in addition to the effect of improving the heat insulation property being easily provided by the porous structure, the radiant heat shielding effect is also easily provided by the infrared ray shielding particles.

[0011] (3) In any of the above configurations, the infrared ray shielding particles may have an average particle diameter of 0.3 μm or more and 22 μm or less. According to this configuration, the infrared ray shielding particles easily provide the radiant heat shielding effect. Furthermore, since the infrared ray shielding particles are filled into the gaps between the porous structures and the connection between the infrared ray shielding particles and other components is prevented, thereby hindering the formation of heat transmission paths, the thermal insulation property is less likely to deteriorate.

[0012] (4) In any of the above configurations, the hollow organic particles may have an average particle diameter of 1 μm or more and 1000 μm or less. According to this configuration, both the desired thermal insulation property and the desired flexibility and resilience can be achieved.

[0013] (5) In any of the above configurations, the hollow organic particles may have a Young's modulus of 1 MPa or more and 30 MPa or less. According to this configuration, the desired flexibility and resilience can be achieved.

[0014] (6) In any of the above configurations, the hollow organic particles can be made of one or more selected from natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber, urethane rubber, silicone rubber, ethylene-vinyl acetate rubber, epichlorohydrin rubber, acrylic rubber, styrene-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer, olefin-based thermoplastic elastomer, polyester, a crosslinked polyacrylonitrile body, a crosslinked polymethyl methacrylate body, and a crosslinked polybutyl methacrylate body. According to this configuration, the production of particles with a hollow structure is easy, and the elastic modulus of the obtained hollow particles can be easily adjusted. This allows the desired flexibility and resilience to be achieved.

[0015] (7) In any of the above configurations, the infrared ray shielding particles may comprise at least one of particles of one kind and particles of a mixture of two or more kinds selected from silicon carbide, kaolinite, montmorillonite, titanium oxide, silicon nitride, mica, aluminum oxide, aluminum nitride, boron carbide, iron oxide, magnesium oxide, tin oxide, zinc oxide, tantalum oxide, manganese ferrite, manganese oxide, nickel oxide, nickel, silver oxide, silver, bismuth oxide, carbon black, graphite, titanium, iron titanium oxide, zirconium, zirconium oxide, zirconium silicate, barium titanate, manganese dioxide, chromium oxide, titanium carbide, tungsten carbide, tungsten oxide, niobium oxide, indium tin oxide, and cerium oxide. According to this configuration, the particles themselves are less likely to heat up because the heat capacity of the infrared ray shielding particles is relatively large. Moreover, the heat resistance of the infrared ray shielding particles is also high.Consequently, this is beneficial for improving the thermal insulation property under high temperature conditions.

[0016] (8) In any of the above configurations, the porous structure may comprise a silica aerogel in which a plurality of silica particles are bonded to form frameworks. A silica aerogel has a good balance between the size of the frameworks and the size of the pores and exhibits excellent thermal insulation properties.

[0017] (9) In any of the above configurations, it may further comprise at least one of a processing aid and inorganic fibers. The processing aid may be used in an appropriate manner according to the manufacturing method with a view to facilitating the production of the heat-insulating material. For example, when water is used as a solvent for the composition for producing the heat-insulating material, by selecting components having a dispersion function or a thickening function, the powder such as the porous structure and water can be more easily mixed. When compression molding the powder such as the porous structure, selecting thermoplastic components improves the moldability. Furthermore, the presence of inorganic fibers is effective for improving the mechanical strength of the heat-insulating material and preventing the porous structure from falling off.

[0018] (10) In any of the above configurations, the hollow organic particles may be discontinuous between the porous structure and the porous structure. In this configuration, many of the hollow organic particles, which are organic components, are distributed without being continuous. Consequently, the hollow organic particles are less likely to form a heat transfer path, and very good thermal insulation properties can be maintained.

[0019] (11) In any of the above configurations, a binder that binds the porous structure, the infrared-shielding particles, and the hollow organic particles may not be included. Generally, organic materials are used as the binder, and if a binder is present, there is a risk that a heat transfer path may be formed through the binder. In this configuration, since there is no binder, very good thermal insulation properties can be achieved under high-temperature conditions.

[0020] (12) In any of the above configurations, the hollow organic particles may comprise single-cavity type particles having a cavity inside. In the single-cavity type particles, only the outermost shell part is made of an organic material, and the rest consists of cavities. Therefore, according to this configuration, it is easy to reduce the density of the heat-insulating material and adjust the flexibility.

[0021] (13) In any of the above configurations, the hollow organic particles may comprise multi-void type particles having a plurality of voids inside. In the case of multi-void type particles, the plurality of voids are arranged inside the particle body made of an organic material. That is, in multi-void type particles, the organic material exists not only in the outermost layer but also inside the particles. Consequently, according to this configuration, it is easy to adjust the resilience of the heat-insulating material. Effects of the invention

[0022] According to the heat-insulating material of this disclosure, excellent heat-insulating properties can be achieved not only at room temperature but also at high temperatures of 500°C or higher. According to the heat-insulating material of this disclosure, flexibility can be achieved that allows deformation against a compressive load and recovery after unloading. DESCRIPTION OF EMBODIMENTS

[0023] The heat-insulating material of this disclosure will be described in detail below. The heat-insulating material of this disclosure is not limited to the following embodiments and can be implemented in various forms with modifications and improvements that can be made by a person skilled in the art within a scope that does not deviate from the gist of this disclosure. <Wärmeisolierendes Material>

[0024] The heat insulating material of this disclosure comprises a porous structure, infrared ray shielding particles, and hollow organic particles. [Porous structure]

[0025] The porous structure has backbones formed by a plurality of interconnected particles, with pores present between the backbones. The diameter of the particles (primary particles) constituting the backbones is preferably about 2 to 5 nm, and the size of the pores formed between the backbones is preferably about 10 to 50 nm. In the case where many of the pores are so-called mesopores with a size of 50 nm or less, since the mesopores are smaller than the mean free path of air, air convection is restricted and heat transfer is inhibited. The shape of the porous structure is not particularly limited, and it can be a spherical shape, irregularly shaped masses, etc., but a tapered shape or a spherical shape is preferred.In this case, the dispersibility of the porous structure improves, making it easier to prepare a composition for producing a heat-insulating material (hereinafter referred to as a "heat-insulating material composition"). Furthermore, the gaps between porous structures can be minimized and the filling amount can be increased, preventing the bonding between infrared-ray shielding particles and hollow organic particles, thereby improving the heat-insulating property. The porous structure can be used as prepared, or it can be further pulverized before use. A grinding device such as a jet mill or a spheroidization treatment device can be used for pulverization. By pulverizing, the corners of the particles are removed, and the particles acquire a rounded shape. This smoothes the surface of the heat-insulating material and makes it less prone to cracking.

[0026] The average particle diameter of the porous structure is preferably 1 μm or more and 1000 μm or less. If the average particle diameter of the porous structure is less than 1 μm, the filling properties of the porous structure deteriorate and the gaps between porous structures increase, making it difficult to achieve the effect of improving thermal insulation properties. On the other hand, if the particle diameter of the porous structure exceeds 1000 μm, since the infrared ray shielding particles fill the gaps between porous structures, there is a risk that the area without infrared ray shielding particles may become larger. In this case, there is a risk that the frequency of infrared rays emitted from the heat source and incident on the infrared ray shielding particles will decrease, thereby reducing the radiant heat shielding effect.For example, the average particle diameter of the porous structure is preferably 8 μm or more, and more preferably 50 μm or more. Furthermore, considering the stability of the heat-insulating material composition and the ease of coating, it is preferably 500 μm or less, and more preferably 300 μm or less. The average particle diameter of the porous structure may be the mean diameter (D). 50 ), which is obtained from the volume-based particle size distribution measured by a laser diffraction / scattering method. It should be noted that when commercially available products are used, catalog values ​​can be used.

[0027] In cases where the particle diameters of porous structures differ, small-diameter porous structures enter the gaps between large-diameter porous structures. This facilitates the achievement of dense packing, allowing a larger filling amount of porous structures. Furthermore, the small-diameter porous structures can inhibit the bonding of infrared-shielding particles and hollow organic particles. As a result, the effect of improving thermal insulation properties becomes stronger. In this regard, it is preferable to use porous structures with a broad particle diameter distribution or to combine two or more types with different average particle diameters.Furthermore, in the manufacturing process of the heat-insulating material, the stirring conditions of the materials may be adjusted so that some of the large-diameter particles are crushed into small-diameter particles.

[0028] From the viewpoint of improving the heat insulating property, the content of the porous structure is preferably 40 mass% or more, and more preferably 50 mass% or more when the total mass of the heat insulating material is 100 mass%. On the other hand, considering the balance between the heat insulating property and the flexibility and resilience, as well as preventing falling off, the content of the porous structure is preferably 75 mass% or less, and more preferably 70 mass% or less when the total mass of the heat insulating material is 100 mass%.

[0029] The porous structure preferably has hydrophobic sites on at least the outer surface and the interior (pore-forming surface). The presence of hydrophobic sites on the surface can prevent moisture and other substances from penetrating the pores, thereby maintaining the porous structure and making the thermal insulation property less likely to be impaired. For example, functions such as hydrophobicity can be imparted to the surface of the porous structure by surface treatment with silane coupling agents and the like. Further, a porous structure having hydrophobic sites can be manufactured by using specific materials as starting materials for the porous structure, or a hydrophobic treatment such as providing hydrophobic groups can be applied during the manufacturing process of the porous structure.

[0030] The type of porous structure is not particularly limited. Primary particles include, for example, inorganic particles such as silicon oxide, aluminum oxide, zirconium oxide, and titanium oxide. Of these, porous structures with silicon oxide as the primary particles are preferred due to their excellent chemical stability. For example, a silicon oxide aerogel in which a plurality of silicon oxide particles are bonded to form skeletons is suitable due to the good balance between the size of the skeletons and the size of the pores. Furthermore, aggregated structures in which nanoparticles with particle diameters of less than 1 µm are bonded to form skeletons are also suitable. Nanoparticles that can be used include those produced from fumed silica, wet silicon oxide, and those particles that have been pulverized or dispersed, or those produced from nanoparticle sols, such ascolloidal silicon oxide and colloidal aluminum oxide.

[0031] The manufacturing process for an aerogel is not specifically limited and can be one in which the drying process is carried out at atmospheric pressure or under supercritical conditions. For example, drying at atmospheric pressure allows for simple and inexpensive manufacturing. Depending on the difference in drying methods when manufacturing an aerogel, those manufactured at atmospheric pressure are sometimes referred to as "xerogels," and those manufactured under supercritical conditions are referred to as "aerogels." However, in this specification, both are collectively referred to as "aerogels." [Infrared radiation shielding particles]

[0032] The infrared ray shielding particles absorb heat from a heat source and re-emit it from the surface on the side of the heat source, thereby shielding radiant heat from the heat source and contributing to improving heat insulation performance, especially under high-temperature conditions. The content of the infrared ray shielding particles is 10 mass% or more to sufficiently provide the radiation heat transfer prevention effect when the total mass of the heat-insulating material is set to 100 mass%. When the content of the infrared ray shielding particles is 15 mass% or more, the radiant heat shielding effect becomes higher.On the other hand, in view of preventing the bonding between infrared ray shielding particles and other components so that the formation of a transmission path for heat becomes difficult, the content of the infrared ray shielding particles is 30 mass% or less, and more preferably 20 mass% or less when the total mass of the heat insulating material is set to 100 mass%.

[0033] In order to fill the gaps between porous structures and prevent the infrared ray shielding particles from bonding with other components, thus making it difficult to form a heat transmission path, it is preferable that the particle diameter of the infrared ray shielding particles be relatively small. However, if the particle diameter is too small, infrared rays are less likely to impinge on the particles, and further, the scattering of infrared rays becomes insufficient, making it difficult to provide the radiant heat shielding effect. In this regard, the average particle diameter of the infrared ray shielding particles is preferably 0.3 μm or more and 22 μm or less. The shape of the infrared ray shielding particles is not particularly limited, and can be, for example, spherical, flat, etc.Regarding the average particle diameter of the infrared ray shielding particles, as in the case of the porous structure, the mean diameter (D. 50 ) obtained from the volume-based particle size distribution measured by a laser diffraction / scattering method may be used, and in the case of using commercially available products, catalog values ​​may be used.

[0034] As the infrared ray shielding particles, there may be mentioned particles of one kind or particles of a mixture of two or more kinds selected from silicon carbide, kaolinite, montmorillonite, titanium oxide, silicon nitride, mica, aluminum oxide, aluminum nitride, boron carbide, iron oxide, magnesium oxide, tin oxide, zinc oxide, tantalum oxide, manganese ferrite, manganese oxide, nickel oxide, nickel, silver oxide, silver, bismuth oxide, carbon black, graphite, titanium, iron titanium oxide, zirconium, zirconium oxide, zirconium silicate, barium titanate, manganese dioxide, chromium oxide, titanium carbide, tungsten carbide, tungsten oxide, niobium oxide, indium tin oxide, and cerium oxide. Of these, from the viewpoint of enhancing the shielding effect of radiant heat, it is preferable that the infrared ray shielding particles comprise high emissivity particles with an emissivity of 0.6 or more in the infrared wavelength range.High-emissivity particles include silicon carbide, kaolinite, silicon nitride, mica, alumina, zirconium oxide, aluminum nitride, zirconium silicate, cerium oxide, boron carbide, manganese oxide, tin oxide, iron oxide, and the like. Furthermore, in view of enhancing the shielding effect of radiant heat by scattering incident infrared rays, a form containing particles with a high refractive index in the infrared wavelength range is also effective. For example, high-refractive index particles with a refractive index of 2.0 or more in the visible light wavelength range are preferred. High-refractive index particles include silicon carbide, titanium oxide, zirconium oxide, silicon nitride, aluminum nitride, zinc oxide, tantalum oxide, tungsten oxide, niobium oxide, cerium oxide, manganese oxide, tin oxide, bismuth oxide, iron oxide, barium titanate, and the like.

[0035] For example, silicon carbide, titanium oxide, silicon nitride, mica, aluminum oxide, aluminum nitride, boron carbide, iron oxide, magnesium oxide, etc., have a relatively high specific heat, so they have a large heat capacity, and the particles themselves do not heat up easily. In this respect, they also contribute to improving the thermal insulation properties of the heat-insulating material. Furthermore, they also have very good heat resistance, thus contributing to improving the heat resistance of the heat-insulating material. Silicon carbide is particularly preferred because it only exhibits a slight increase in thermal conductivity even in a high-temperature atmosphere of about 800°C. [Hollow organic particles]

[0036] The content of the hollow organic particles is preferably 5 mass% or more, more preferably 10 mass% or more, and even more preferably 15 mass% or more, when the total mass of the heat-insulating material is 100 mass%, from the viewpoint of imparting flexibility and resilience to the heat-insulating material. On the other hand, from the viewpoint of increasing the content of components contributing to heat insulation to improve the heat-insulating property and preventing the connection between the hollow organic particles and other components, making it difficult to form a heat transfer path, the content of the hollow organic particles is preferably 30 mass% or less, and more preferably 20 mass% or less, when the total mass of the heat-insulating material is 100 mass%.

[0037] If the particle diameter of the hollow organic particles is too small, it becomes difficult to obtain the effect of improving flexibility and resilience. Therefore, the average particle diameter of the hollow organic particles is preferably 1 μm or more, and more preferably 10 μm or more. On the other hand, if the particle diameter is too large, the co-located infrared ray shielding particles may be separated from each other, which may deteriorate the heat insulating property at high temperatures. Therefore, the average particle diameter of the hollow organic particles is preferably 1000 μm or less, and more preferably 500 μm or less and 200 μm or less. The shape of the hollow organic particles is not particularly limited and can be spherical, flat, etc.Regarding the average particle diameter of the hollow organic particles, as in the case of the porous structure, the mean diameter (D. 50 ) obtained from the volume-based particle size distribution measured by a laser diffraction / scattering method may be used, and in the case of using commercially available products, catalog values ​​may be used.

[0038] The hollow organic particle is a particle having a cavity inside, and the cavity may be one cavity or a plurality of cavities. The former single-cavity type particle, also called a balloon structure, includes a shell part formed of an organic material and a single cavity present inside. The latter multi-cavity type particle includes a particle body formed of an organic material and a plurality of cavities present inside. The multi-cavity type particle is a concept that includes porous particles. As the hollow organic particle, one of the single-cavity type particle and the multi-cavity type particle may be used, or both may be used in combination.The hollow organic particles can be produced, for example, by foaming organic particles or by crushing an organic foam.

[0039] The organic material is not specifically limited. Preferred materials include, for example, crosslinked rubbers such as natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber, urethane rubber, silicone rubber, ethylene-vinyl acetate rubber, epichlorohydrin rubber, and acrylic rubber; thermoplastic elastomers such as styrene-based, vinyl chloride-based, and olefin-based; and resins such as polyester, crosslinked polyacrylonitrile, crosslinked polymethyl methacrylate, and crosslinked polybutyl methacrylate. The surface of the hollow organic particles may be surface-treated for purposes such as preventing dust generation and improving handling, improving flame retardancy, and inorganic particles or the like may be applied.Furthermore, the organic material may contain flame retardants or the like to improve flame retardancy.

[0040] From the viewpoint of imparting a desired resilience to the heat-insulating material, the elastic modulus of the hollow organic particles is preferably 1 MPa or more, and more preferably 2.5 MPa or more. On the other hand, from the viewpoint of imparting a desired flexibility against compression to the heat-insulating material, the elastic modulus of the hollow organic particles is preferably 30 MPa or less, and more preferably 20 MPa or less.

[0041] In this specification, the elastic modulus of hollow organic particles is calculated from the results of the following compression test. First, the hollow organic particle powder is placed in a cylindrical container made of SUS with a diameter of 11.3 mm. Next, a cylindrical press made of SUS with a diameter of 11.2 mm is inserted into the cylindrical container, and the hollow organic particle powder is pressed by the press's own weight (load of 2 N). This process is repeated, and the initial filling height of the hollow organic particle powder is set to 14 mm. The press is placed in the compression testing machine while inserted into the cylindrical container. Then, using the Tensilon universal material testing machine "RTF1350" manufactured by A&D Co., Ltd., the compression test is carried out.A compression test is conducted in which the upper surface of the filled powder is repeatedly pressed with the compression device. The conditions of the compression test are as follows. Pressing speed: 6 mm / min. Upper limit of pressure load: 3 MPa. Number of pressing operations: 10 times.

[0042] After the compression test, a stress-compression rate curve is generated based on the obtained data, where the horizontal axis represents the compression rate and the vertical axis represents the compressive stress. The compression rate on the horizontal axis is a value calculated by the following equation (I). Compression rate (%) = amount of compression by the compression device (mm) / 14 [initial filling height of the hollow organic particle powder] (mm) × 100...(I) Then, in the stress-compression rate curve of the 10th compression, the point where the compressive stress is 0 MPa and the point where the compressive stress is 3 MPa are connected by a straight line, and the value obtained by multiplying the slope of the resulting line by 100 is defined as the elastic modulus of the hollow organic particles.

[0043] The hollow organic particles are arranged between the porous structures. In order to prevent the formation of a heat transfer path through the hollow organic particles, it is preferable that most of the hollow organic particles be arranged discontinuously, in other words, in a scattered manner. For example, when a heat-insulating material is manufactured in a sheet form and the thickness direction becomes the direction of heat transfer, the hollow organic particles do not form a matrix and do not continue in the thickness direction, making it less likely that the heat-insulating property will be impaired. [Other ingredients]

[0044] The heat-insulating material of the disclosure may include other components such as processing aids, inorganic fibers, inorganic reinforcing particles, flame retardants, organic fibers, hollow inorganic particles, organic binders, etc., in addition to the porous structure, infrared-shielding particles, and hollow organic particles, to the extent that they do not impair the effects achieved by the disclosure. It should be noted that when a binder is present that binds the constituent materials such as the porous structure, there is a risk that a heat transfer path may be formed by the binder. Therefore, from the viewpoint of preventing the formation of a heat transfer path and achieving excellent heat insulating properties at high temperatures, it is preferable that the heat-insulating material be in a form without a binder. (1) Processing aids

[0045] Porous structures with hydrophobic patches on their surface or inside are not readily compatible with water. Of these, silica aerogels and aggregated structures of silica powder tend to float on water due to their low density.

[0046] In order to facilitate manufacturing, such as improving the water-suspensibility of the porous structure, and to facilitate dispersing the porous structure when preparing a heat-insulating material composition using water as a solvent, it is preferable to include a processing aid according to the manufacturing process of the heat-insulating material. Examples of processing aids include surfactants, thickeners, and suspending agents.

[0047] Surfactants include ionic surfactants (cationic surfactants, anionic surfactants, amphoteric surfactants) and non-ionic surfactants. For example, when an ionic surfactant is used, even with relatively small amounts, the viscosity of the heat-insulating material composition can be increased or the dispersion of materials, such as the porous structure, in the heat-insulating material composition can be stabilized. Examples of ionic surfactants include sodium carboxymethyl cellulose (CMC-Na), polycarboxylic acid amine salts, polycarboxylic acid ammonium salts, polycarboxylic acid sodium salts, and TEMPO-oxidized cellulose nanofibers (CNF-Na). When a non-ionic surfactant is used, materials such asThe porous structure can be more easily incorporated into the solvent when preparing the heat-insulating material composition. Furthermore, when these materials aggregate or separate in the heat-insulating material composition, they can be more easily redispersed or the solvent can be more easily released when the heat-insulating material is dried and molded. Examples of nonionic surfactants include polyethylene oxide (PEO) and polyvinyl alcohol (PVA). Furthermore, it is preferable to use both nonionic surfactants and ionic surfactants in combination because the above-mentioned effects of each surfactant can be adjusted as desired. For example, the water retention of PEO is not particularly high.As a result, when the heat-insulating material composition is manufactured, water does not easily penetrate into the gaps between the porous structures, and voids are less likely to occur when water evaporates during drying. As a result, infrared-shielding particles and hollow organic particles can be more easily filled into the gaps between the porous structures. Furthermore, small-diameter porous structures can be more easily filled into the gaps between large-diameter porous structures.

[0048] When processing aids are present on the surface or in the gaps of materials such as porous structures, there is a risk that a heat transfer path may be formed through the processing aids. Therefore, in order to prevent the formation of a heat transfer path, it is preferable that the content of the processing aid be 10 mass% or less, and more preferably 7 mass% or less, when the total mass of the heat-insulating material is 100 mass%. (2) Inorganic fibers

[0049] Inorganic fibers physically entangle around the porous structure, thereby improving the mechanical strength of the heat-insulating material while preventing the porous structure from peeling off. The type of inorganic fibers is not specifically limited, but considering heat resistance and mechanical strength, glass fibers and ceramic fibers such as alumina fibers are preferred. From the viewpoint of providing a reinforcing effect, the content of inorganic fibers is preferably 5 mass% or more when the total mass of the heat-insulating material is 100 mass%. From the viewpoint of preventing the formation of a heat transfer path, it is preferable to set the content to 15 mass% or less. Considering both the reinforcing effect and the prevention of the formation of a heat transfer path, the length of the inorganic fibers is preferably 16 mm or less. (3) Inorganic reinforcing particles

[0050] To improve the mechanical strength of the heat-insulating material, inorganic reinforcing particles can be incorporated into the heat-insulating material. The type of inorganic reinforcing particles is not specifically limited, and for example, particles with a relatively high hardness and specific surface area, such as precipitated silicon oxide, silica gel, fumed silica, wollastonite, potassium titanate, magnesium silicate, glass flakes, calcium carbonate, barium sulfate, etc., can be used. (4) Flame retardants

[0051] By incorporating a flame retardant, flame retardancy can be imparted to the heat-insulating material. Known flame retardants, such as halogen-based, phosphorus-based, and metal hydroxide-based types, can be used. Considering environmental influences, it is preferable to use phosphorus-based flame retardants. Examples of phosphorus-based flame retardants include ammonium polyphosphate, red phosphorus, and phosphate esters. Of these, those that are insoluble in water or those coated with a water-resistant resin are preferred because the flame retardant is less likely to flow out even if it comes into contact with moisture during use. For example, ammonium polyphosphate and resin-coated ammonium polyphosphate are preferred. <Verfahren zur Herstellung eines wärmeisolierenden Materials>

[0052] The heat-insulating material of the disclosure can be produced by compression molding a material comprising a porous structure, infrared-ray shielding particles, and hollow organic particles. Alternatively, it can be produced by applying and drying a liquid (including slurry) heat-insulating material composition to a base material or by compression molding a clay-like heat-insulating material composition.

[0053] The thickness of the heat-insulating material can be appropriately determined according to the application. For example, from the viewpoint of heat-insulating property, it is preferable that the thickness of the heat-insulating material be set to 0.1 mm or more, 0.5 mm or more, or even 1 mm or more. If the heat-insulating material is too thick, it not only becomes expensive but also difficult to insert the heat-insulating material into narrow spaces. Therefore, for example, 10 mm or less, 8 mm or less are suitable. In particular, from the viewpoint of making the heat-insulating material thinner and increasing flexibility, it is preferable to set the thickness of the heat-insulating material to 5 mm or less, or even 3 mm or less. The density of the heat-insulating material is preferably 0.4 g / cm 3 or less. <Nutzungsform des wärmeisolierenden Materials>

[0054] The heat-insulating material of the disclosure can be used alone, or it can be used together with a base material that supports the heat-insulating material, an outer material that houses the heat-insulating material, etc. The base material can be arranged only on one side in the thickness direction of the heat-insulating material, or it can be arranged on two sides so as to surround the heat-insulating material. Further, the heat-insulating material can be covered with a single base material, using the base material as the outer material. An adhesive layer can be arranged between the heat-insulating material and the base material. The adhesive layer can include, in addition to adhesive components, flame retardants, etc.

[0055] Materials for the base material include fabric, resin, paper, steel sheet, etc. Fibers that make up the fabric include glass fibers, rock wool, ceramic fibers, alumina fibers, silica fibers, carbon fibers, metal fibers, polyimide fibers, aramid fibers, polyphenylene sulfide (PPS) fibers, etc. Common ceramic fibers include refractory ceramic fibers (RCF), polycrystalline alumina fibers (PCW), and alkaline earth silicate (AES) fibers. Of these, AES fibers are safer because they are biodegradable. Resins include polyethylene terephthalate (PET), polyimide, polyamide, PPS, etc. Papers include pulp, mixed materials of pulp and magnesium silicate, etc. Steel sheets include GALVALUME steel sheet (registered trademark), galvanized iron sheet, stainless steel (SUS) sheet, iron sheet, titanium sheet, etc.The form of the base material is not particularly limited and includes a woven fabric, a nonwoven fabric, a film, a sheet, etc. The base material may be a single layer or may be a laminate in which the same material or different materials are laminated in two or more layers.

[0056] For example, woven fabrics (a woven fabric), nonwoven fabrics made of inorganic fibers such as glass fibers or metal fibers, such as glass cloth, and fire-resistant heat-insulating paper made of a blend of pulp and magnesium silicate have relatively low thermal conductivity and excellent shape retention in high-temperature atmospheres. Furthermore, by using a base material with high heat resistance, the heat-insulating material of the disclosure can be used for applications requiring high heat resistance, thereby expanding its applications. Furthermore, by using a fire-resistant base material, safety is further improved. A base material with high heat resistance can be made of glass fibers, rock wool, ceramic fibers, polyimide, PPS, etc., and includes in particular a glass fiber fleece, a glass fabric, an aluminum-glass fabric, an AES wool paper, a polyimide fiber fleece, etc. Examples

[0057] Next, the disclosure will be described more specifically by means of examples. <Herstellung von wärmeisolierenden Materialproben>

[0058] Heat-insulating material samples with the compositions shown in Table 1 below were prepared. For samples of Examples 1 to 3, water was first weighed into a resin container, a surfactant as a processing aid was added, and stirring was carried out at 800 rpm for 60 minutes using an air-driven blade stirrer to dissolve the surfactant in water. After stopping stirring, silicon carbide (SiC) powder as infrared ray shielding particles and a hollow organic particle powder were added, and stirring was continued at 800 rpm for 15 minutes. While continuing to stir, silica aerogel powder was added as a porous structure and completely wetted in the liquid. Then, glass fibers as inorganic fibers were added and stirring was carried out at 800 rpm for 30 minutes.Subsequently, additional stirring was carried out at 1000 rpm for 10 minutes to produce a clay-like heat-insulating material composition.

[0059] For samples of Comparative Examples 1 to 3, heat-insulating material compositions were prepared in the same manner as the samples of Examples 1 to 3, except that the hollow organic particle powder was not included and instead an organic binder was included in the sample of Comparative Example 2 and a solid organic particle powder was included in the sample of Comparative Example 3.

[0060] The details of the materials are as follows. Silicon oxide aerogel powder: Pulverized product of "Aerogel Particles P200," manufactured by Cabot Corporation, average particle diameter 100 µm. Silicon carbide powder: "Fuji Random GC#4000," manufactured by Fuji Manufacturing Co., Ltd., average particle diameter 5 µm. Hollow organic particle powder: acrylonitrile-based copolymer microballoons, “Matsumoto Microsphere (registered trademark) MFL-HD60CA,” manufactured by Matsumoto Yushi-Seiyaku Co., Ltd., average particle diameter 50 to 70 µm, elastic modulus 17 MPa. Surfactant: Polyethylene oxide "PEO-8," manufactured by Sumitomo Seika Chemicals Co., Ltd., viscosity-average molecular weight 1.7 million to 2.2 million. Glass fibers: "ECS03-615," manufactured by Central Glass Fiber Co., Ltd., length 3 mm, fiber diameter 9 µm. Organic binder: Silicone emulsion, “Siltech E-2152,” manufactured by Siltech Corporation. Solid organic particle powder: Acrylic rubber powder, “XM-TM-1,” manufactured by Matsumoto Yushi-Seiyaku Co., Ltd., average particle diameter 30 µm.

[0061] Next, a base was prepared by stacking a first spacer plate made of SUS on a glass fiber paper. The first spacer plate had a thickness of 7 mm and had a 150 mm square injection hole formed in the center. The prepared heat-insulating material composition was filled into the injection hole of the first spacer plate and formed into a plate shape. Subsequently, the first spacer plate was removed, a glass fiber paper was stacked from above, and then a second spacer plate was placed on top, thus forming a laminate consisting of "glass fiber paper / heat-insulating layer composition / glass fiber paper / second spacer plate."The second spacer plate had a thickness of 6 mm and, corresponding to the first spacer plate, had a square-shaped injection hole of 150 mm square formed in the center. The pre-formed heat-insulating layer composition was placed in the injection hole of the second spacer plate. Separately, a first plate material made of aluminum with a thickness of 5 mm and a size of 320 mm square, and a second plate material made of aluminum with a thickness of 1 mm and a size of 320 mm square, were prepared. A plurality of groove portions were formed on one side of the first plate material. Each of the plurality of groove portions had a linear shape with a width of 2.5 mm, a depth of 3 mm, and a length of 200 mm, and was formed in parallel at intervals of 5 mm.The second plate material had punched holes with a diameter of 1 mm, always formed at intervals of 2 mm. The second plate material was stacked on one side of the first plate material, and the laminate was placed on top. Then, the second plate material was placed on the laminate, and the first plate material was stacked so that the side with the groove portions faced the second plate material. In this state, pressure drying was performed by hot pressing at a temperature of 165 °C and a load of about 980 kN for 10 minutes. After that, the laminate was cooled to room temperature (20 °C ± 5 °C), and the first plate material, the second plate material, the second spacer plate, and the upper and lower glass fiber papers were removed, so that a plate-shaped heat-insulating material sample with a thickness of 6 mm was obtained.The density of the obtained heat-insulating material sample was measured using the water displacement density meter “DSG-1” manufactured by Toyo Seiki Seisaku-sho, Ltd. <Verfahren zur Bewertung der Wärmeisoliereigenschaft> (1) Measurement of thermal conductivity at room temperature

[0062] The thermal conductivity of the heat-insulating material sample at room temperature (20 °C ± 5 °C) was measured using the “Non-steady-state thermal conductivity tester Quick Lambda HC-10” manufactured by EKO Instruments Co., Ltd. (2) Measurement of thermal conductivity at high temperature

[0063] The thermal conductivity of the prepared heat-insulating material sample at 800°C was measured using the "Quick Thermal Conductivity Meter QTM-700" and the "High Temperature Probe PD-31N" manufactured by Kyoto Electronics Manufacturing Co., Ltd., as follows. First, three heat-insulating material samples were stacked to form two laminates with a thickness of 18 mm. These laminates were placed on each of the upper and lower sides of the probe, surrounding the probe. A weight of approximately 5 kg, which was not heavy enough to destroy the laminates, was placed on top, and the resulting sample was placed in an electric furnace. Then, the temperature in the electric furnace was raised to 800°C, and after the furnace temperature stabilized, the thermal conductivity was measured. (3) Evaluation criteria

[0064] For thermal insulation performance at room temperature, a thermal conductivity of 0.050 W / m K or less at room temperature was considered acceptable (indicated by ◦ in Table 1 below), and a thermal conductivity of more than 0.050 W / m K was considered unacceptable (indicated by × in the same table). Regarding thermal insulation performance at high temperature, a thermal conductivity of less than 0.30 W / m K at 800 °C was considered acceptable (indicated by ◦ in the same Table 1), and a thermal conductivity of 0.30 W / m K or more was considered unacceptable (indicated by × in the same table). <Verfahren zur Bewertung der Flexibilität und des Rückstellvermögens>

[0065] Using the Tensilon universal material testing machine "RTF 1350" manufactured by A&D Co., Ltd., a compression test was performed on the prepared heat-insulating material sample (a square plate with dimensions of 150 mm long, 150 mm wide, and 6 mm thick) by pressing the central section with a compression end with a diameter of 60 mm. The compression test was performed by reciprocating the compression end at a speed of 1 mm / minute with an upper limit of compressive stress set to 1.0 MPa. The section where the compressive stress changed from 0.02 MPa to 1.0 MPa to 0.02 MPa was set as one cycle, which was repeated for 3 cycles.Based on the data obtained from the compression test, a load-compression rate curve was constructed with the compression rate on the horizontal axis and the compressive load on the vertical axis. The compression rate on the horizontal axis is the value calculated by the following equation (II).

[0066] Compression rate (%) = Amount of pressing by the compression end (mm) after the compressive load in the pressing process of the first cycle has reached 0.01 MPa / Thickness of the heat-insulating material sample (mm) when the compressive load in the Pressing process of the first cycle has reached 0.01 MPa×100 [Flexibility]

[0067] In the stress-compression rate curve of the second cycle, the point where the compressive stress at the beginning of the cycle was 0.02 MPa and the point where the compressive stress was 1.0 MPa were connected by a straight line, and the value obtained by multiplying the slope of the resulting line by 100 was used as the index value for the flexibility of the heat-insulating material sample. That is, the index value for flexibility is the value calculated by the following equation (III). Flexibility index value=(1.0−0.02) / (a−b)×100 [a: Compression rate (%) when the pressure load is 1.0 MPa, b: Compression rate (%) when the pressure load at the beginning of the cycle is 0.02 MPa]

[0068] In this example, a Flexibility Index value of 4.0 or less was considered acceptable (indicated by o in Table 1 below), and a value greater than 4.0 was considered unacceptable (indicated by × in the same table). [Recovery capacity]

[0069] In the stress-compression rate curve of the second cycle, the value obtained by subtracting the compression rate when the compressive load was 0.02 MPa at the end of the cycle from the compression rate when the compressive load was 1.0 MPa was used as the recovery index value of the heat-insulating material sample. In this example, a recovery index value of 25% or more was considered acceptable (indicated by ◦ in Table 1 below), and a value of less than 25% was considered unacceptable (indicated by × in the same table). [Evaluation results of thermal insulation properties, flexibility and resilience]

[0070] Table 1 shows the composition, density and evaluation results of various properties of the heat-insulating material samples. [Table 1] Example 1 Example 2 Example 3 Comparison example 1 Comparison example 2 Comparison example 3 Material (unit: g) Organic component Hollow organic particle 160 92 42 - - - Organic binder - - - - 160 - Massive organic particle - - - - - 160 Porous structure Silicon oxide aerogel 282 Infrared radiation shielding particles silicon carbide 58 Processing aids Surfactant 11 Inorganic fibers Glass fibers 32 Water 685 637 603 574 378 604 Content of organic component [mass%] 29 19 10 0 29 29 Density [g / cm 3 ] 0,16 0,19 0,21 0,27 0,23 0,29 Characteristic Thermal insulation properties Thermal conductivity at room temperature [W / m · K] 0,030 0,029 0,024 0,022 0,034 0,033 Evaluation ◯ ◯ ◯ ◯ ◯ ◯ Thermal conductivity at high temperatures [W / m · K] 0,18 0,20 0,16 0,15 0,30 0,38 Evaluation ◯ ◯ ◯ ◯ x x flexibility Index value 3,2 3,2 4,0 4,5 5,8 4,5 Evaluation ◯ ◯ ◯ × × × resilience Index value [%] 33 32 27 23 18 23 Evaluation ◯ ◯ ◯ × × ×

[0071] As shown in Table 1, it was confirmed that the samples of Examples 1 to 3 containing hollow organic particles in a predetermined proportion had excellent thermal insulation properties at both room temperature and high temperature. It was also confirmed that the samples of Examples 1 to 3 satisfied both the flexibility and recovery properties. In contrast, according to the samples of Comparative Examples 1 to 3, which did not contain hollow organic particles, both the flexibility and recovery properties were poor. Furthermore, in the sample of Comparative Example 2 in which an organic binder was blended and in the sample of Comparative Example 3 containing solid organic particles instead of hollow organic particles, the thermal insulation properties decreased at high temperatures. INDUSTRIAL APPLICABILITY

[0072] The heat-insulating material of the disclosure is suitable for heat-insulating materials for vehicles, heat-insulating materials for buildings, heat-insulating materials for electronic devices, heat-insulating materials for heat-retaining and cold storage containers, and the like. Among these, it is particularly suitable for heat-insulating materials for battery packs requiring high-temperature heat-insulating properties and heat-insulating mats requiring cushioning properties. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2017 / 038646

[0003] JP 2013-543036

[0003]

Claims

[1] Thermally insulating material comprising: a porous structure in which a plurality of particles are bonded to form skeletons and which has pores between the skeletons, infrared ray shielding particles and hollow organic particles, wherein the infrared ray shielding particles have a content of 10 mass% or more and 30 mass% or less when a mass of the heat insulating material is 100 mass%, and the hollow organic particles have a content of 5 mass% or more and 30 mass% or less when a mass of the heat-insulating material is 100 mass%. [2] The heat insulating material according to claim 1, wherein the porous structure has an average particle diameter of 1 µm or more and 1000 µm or less. [3] The heat insulating material according to claim 1, wherein the infrared ray shielding particles have an average particle diameter of 0.3 µm or more and 22 µm or less. [4] The heat insulating material according to claim 1, wherein the hollow organic particles have an average particle diameter of 1 µm or more and 1000 µm or less. [5] The heat insulating material according to claim 1, wherein the hollow organic particles have a modulus of elasticity of 1 MPa or more and 30 MPa or less. [6] The heat insulating material according to claim 1, wherein the hollow organic particles are made of one or more selected from natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber, urethane rubber, silicone rubber, ethylene-vinyl acetate rubber, epichlorohydrin rubber, acrylic rubber, styrene-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer, olefin-based thermoplastic elastomer, polyester, a crosslinked polyacrylonitrile body, a crosslinked polymethyl methacrylate body, and a crosslinked polybutyl methacrylate body. [7] The heat insulating material according to claim 1, wherein the infrared ray shielding particles comprise at least one of particles of one kind and particles of a mixture of two or more kinds selected from silicon carbide, kaolinite, montmorillonite, titanium oxide, silicon nitride, mica, aluminum oxide, aluminum nitride, boron carbide, iron oxide, magnesium oxide, tin oxide, zinc oxide, tantalum oxide, manganese ferrite, manganese oxide, nickel oxide, nickel, silver oxide, silver, bismuth oxide, carbon black, graphite, titanium, iron titanium oxide, zirconium, zirconium oxide, zirconium silicate, barium titanate, manganese dioxide, chromium oxide, titanium carbide, tungsten carbide, tungsten oxide, niobium oxide, indium tin oxide and cerium oxide. [8] The thermal insulating material according to claim 1, wherein the porous structure comprises a silica aerogel in which a plurality of silica particles are bonded to form skeletons. [9] The heat insulating material according to claim 1, further comprising at least one of a processing aid and inorganic fibers. [10] The heat insulating material according to claim 1, wherein the hollow organic particles are discontinuous between the porous structure and the porous structure. [11] The heat insulating material according to claim 1, which does not comprise a binder that binds the porous structure, the infrared ray shielding particles and the hollow organic particles. [12] The heat insulating material according to claim 1, wherein the hollow organic particles comprise single-cavity type particles having a cavity therein. [13] The heat insulating material according to claim 1, wherein the hollow organic particles comprise particles of the multi-void type having a plurality of voids inside.