Heat insulating material

Abstract

Provided is a heat insulating material comprising a heat insulating layer containing inorganic particles and inorganic fibers. The heat insulating material satisfies at least one of the following conditions: (A) an electrical conductivity ES of extracted water obtained by heating and extracting 1.0 g of the heat insulating layer with 50 g of ultrapure water is 10-60 μS / cm; (B) the heat insulating layer has a moisture absorption amount of less than 3.5% as calculated from the normal mass W0 of the heat insulating layer and the mass W1 after the layer has been allowed to stand for 72 h in an environment of 85°C and 85% RH according to the following formula: moisture absorption amount [%] = ((W1 - W0) / W0 × 100; and (C) the heat insulating layer has a moisture absorption breakdown voltage of 1.25 kV / mm or more as measured after the layer has been allowed to stand for 72 h in an environment of 85°C and 85% RH for moisture absorption.

Description

insulation

[0001] The present application claims priority to Japanese Patent Application No. 2023-170255, filed on September 29, 2023, the entire contents of which are incorporated herein by reference.

[0002] Non-aqueous electrolyte secondary batteries such as lithium ion batteries are widely used as power sources for electrically powered vehicles such as hybrid cars and electric cars, portable electronic devices such as mobile terminals, mobile phones and laptop computers, wearable devices, etc. For example, in modules or packs of lithium ion batteries mounted on electric cars and the like, a plurality of cells are stacked, and adjacent cells are not in direct contact with each other, and a heat insulating material is sometimes placed between the cells to further insulate them from each other.

[0003] Patent Document 1 describes an insulating sheet to be interposed between battery cells of a battery pack, which is manufactured by a wet papermaking method using a blend of first particles made of silica particles, second particles made of titania or the like, and linear or needle-shaped inorganic fibers, and describes that the sheet exhibits excellent insulating properties even at high temperatures of 500°C or higher.

[0004] Japanese Patent Application Publication No. 2021-34278

[0005] Some thermal insulating materials are used in applications requiring not only thermal insulation but also electrical insulation (short-circuit prevention). For example, in battery modules or battery packs (hereinafter collectively referred to as "battery modules, etc.") in which multiple cells are stacked, it is desirable for the thermal insulating material disposed between adjacent cells to have the function of preventing short circuits between the cells, particularly when the exterior materials of the cells are conductive (typically made of metal). In recent years, the use of nonaqueous electrolyte secondary batteries as power sources for vehicles has become increasingly widespread, and as a result, battery modules, etc., are increasingly exposed to various usage environments. However, previous studies on the insulating properties of thermal insulating materials disposed between cells have focused mainly on the performance of the thermal insulating material in a standard state and have not fully considered the possibility that the state of the thermal insulating material may change due to the usage environment, etc. For example, if a technology were provided to improve the insulating performance of a thermal insulating layer in a hygroscopic state, it would be useful because it would improve the insulating reliability of thermal insulating materials equipped with such a thermal insulating layer.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a heat insulating material having good insulation reliability against environmental changes.

[0007] The thermal insulation material provided herein comprises a thermal insulation layer that includes inorganic particles and inorganic fibers.

[0008] In some embodiments, the heat insulating material has an electrical conductivity E Ｓ In the composition containing inorganic particles and inorganic fibers, the electrical conductivity E Ｓ A heat insulating layer having a value within the above range is likely to have good insulating performance even in a hygroscopic state, and can constitute a heat insulating material with good insulating reliability against environmental changes.

[0009] In some embodiments, the heat insulating layer has a moisture absorption amount of less than 3.5%, calculated from the normal mass W0 and the mass W1 after standing in an environment of 85°C and 85% RH for 72 hours using the following formula: Moisture absorption amount [%] = ((W1 - W0) / W0) × 100. Heat insulating layers that satisfy the above moisture absorption amount tend to exhibit good insulating performance even in a hygroscopic state, and are suitable as a component of a heat insulating material that has good insulating reliability against environmental changes.

[0010] In some embodiments, the heat insulating layer has a moisture breakdown voltage of 1.25 kV / mm or more, measured after being left to stand for 72 hours in an environment of 85°C and 85% RH to absorb moisture. A heat insulating layer that satisfies the moisture breakdown voltage requirement exhibits good insulating performance even in a moisture-absorbed state, and is therefore suitable as a component of a heat insulating material that has good insulation reliability against environmental changes.

[0011] In some aspects of the technology disclosed herein, the heat insulating layer preferably contains the inorganic particles and inorganic fibers in a mass ratio of 50:50 to 95:5. A mass ratio in this range makes it easy to obtain a heat insulating layer that has both good heat insulating properties and mechanical strength.

[0012] In some embodiments of the technology disclosed herein, the inorganic particles preferably include silicon dioxide (silica) particles, and the inorganic fibers preferably include glass fibers. A heat insulating layer containing silica particles and glass fibers is likely to achieve both good heat insulation and mechanical strength.

[0013] In some embodiments, the insulating layer has a density of 0.2 g / cm ３ ~0.5g / cm ３ and preferably has a thermal conductivity of 0.045 W / (m·K) or less under conditions of 80° C. and a pressure of 2 MPa. A heat insulating layer that satisfies these properties has an excellent balance between light weight and low thermal conductivity under pressure conditions.

[0014] The heat insulating material disclosed herein can be used, for example, as a component of a heat insulating member disposed between adjacent cells in a battery module or battery pack including an array of multiple cells. In particular, taking advantage of its excellent insulation reliability against environmental changes, the heat insulating material disclosed herein is suitable as a heat insulating material disposed between adjacent cells in an in-vehicle battery module or battery pack (for example, used as a power source for driving a vehicle).

[0015] This specification also provides an insulating material disposed between adjacent cells in a battery module or battery pack including a plurality of arranged cells. The insulating material includes any of the insulating layers disclosed herein and a coating layer that covers the insulating layer in a breathable manner. An insulating material having such a configuration has good deformability due to the breathability of the coating layer, and is easily compressively deformed due to, for example, volumetric expansion of the cells. Furthermore, the insulating layer in the insulating material disclosed herein can exhibit good insulating performance even when it absorbs moisture that has penetrated through the coating layer.

[0016] Appropriate combinations of the elements described in this specification may also be included within the scope of the invention for which patent protection is sought by this patent application.

[0017] FIG. 1 is a perspective view schematically showing an example of a battery module in which a heat insulating material according to an embodiment is disposed between cells. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is a perspective view schematically showing a heat insulating material according to an embodiment. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3. FIG. 5 is a cross-sectional view schematically showing a heat insulating material according to another embodiment. FIG. 6 is a cross-sectional view schematically showing a heat insulating material according to another embodiment.

[0018] Preferred embodiments of the present invention are described below. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings for carrying out the invention described in this specification and the common general technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actual product provided.

[0019] In this specification, "weight" may be read as "mass." For example, "% by weight" may be read as "% by mass," and "parts by weight" may be read as "parts by mass."

[0020] The heat insulating material disclosed in this specification includes a heat insulating layer containing inorganic particles and inorganic fibers. A heat insulating layer containing inorganic fibers in addition to inorganic particles (e.g., silica particles) makes it easier to obtain a heat insulating material that has high heat insulating properties and excellent mechanical strength.

[0021] (Inorganic Particles) The type of inorganic particles is not particularly limited, and examples thereof include silica particles, zinc oxide particles, aluminum oxide particles, titanium oxide particles, silicon carbide particles, ilmenite particles (ilmenite, FeTiO), zirconium silicate particles, iron (III) oxide particles, iron (II) (wustite (FeO) particles, magnetite particles (Fe ３ O ４ ), hematite particles (Fe ２ O ３)), chromium dioxide particles, zirconium oxide particles, manganese dioxide particles, zirconia sol, titania sol, silica sol, alumina sol, bentonite particles, kaolin particles, etc. Furthermore, carbon-based particles such as graphite, carbon black, and carbon powder can also be used as the inorganic particles in the technology disclosed herein. Graphite having a particle diameter of 18 μm or less is preferred. The particle diameter of graphite is measured in the same manner as the average primary particle diameter of silica particles. If a nominal value for particle diameter is provided by a manufacturer, this nominal value may be used. The shape of graphite can be any of flake, scaly, spherical, etc. Commercially available flake graphite products include BF-3AK, FBF, BF-10AK, etc. manufactured by Chuetsu Graphite Co., Ltd., and GE-1, Z-5F, CNP7, V-10F, etc. manufactured by Ito Graphite Co., Ltd. Commercially available flaky graphite products include HLP and SB-1 manufactured by Chuetsu Graphite Industries Co., Ltd. Commercially available spherical graphite products include SG-BH8 manufactured by Ito Graphite Industries Co., Ltd. Commercially available carbon black products include TOKABLACK #5500 manufactured by Tokai Carbon Co., Ltd. and MA100 manufactured by Mitsubishi Chemical Corporation. While not particularly limited, in some embodiments using carbon black as inorganic particles, carbon black with a relatively high DBP oil absorption is generally preferred from the perspective of reducing thermal conductivity. The DBP oil absorption is suitably, for example, 40 mL / 100 g or more, and preferably 60 mL / 100 g or more or 80 mL / 100 g or more. The heat insulating material may contain one type of inorganic particle or two or more types of inorganic particles. The inorganic particles are preferably capable of suppressing thermal radiation, more specifically, inorganic particles having an absorption peak in the infrared region. The absorption peak in the infrared region can be measured using an infrared spectrophotometer. The inorganic particles may also function as a binder that binds the inorganic fibers together.

[0022] The thermal insulation layer according to some embodiments contains silicon dioxide (silica, SiO ２) is preferable. Silica can be classified into crystalline silica, amorphous silica, etc. based on structural characteristics, and can be classified into natural silica, synthetic silica, etc. based on the method of acquisition. Synthetic silica can be classified into dry silica, wet silica, silica aerogel, etc. based on the production method. Dry silica can be classified into silica obtained by a combustion method, silica obtained by an arc method, etc., and wet silica can be classified into silica obtained by a gel method, silica obtained by a precipitation method, etc. The type of silica particles is not particularly limited, but dry silica and silica aerogel are preferable. Among dry silicas, fumed silica is more preferable. Among fumed silicas, hydrophilic fumed silica is particularly preferable. Note that hydrophilic fumed silica refers to fumed silica that mainly has hydrophilic silanol groups (Si—OH) on the surface, and generally refers to fumed silica in which the silanol groups have not been replaced with hydrophobic groups by surface treatment or the like.

[0023] The apparent specific gravity of the silica particles is not particularly limited and is usually 30 g / L to 130 g / L, preferably 40 g / L or more, for example 50 g / L or more, and preferably 120 g / L or less, for example 100 g / L or less. In some embodiments, the apparent specific gravity of the silica particles may be, for example, 80 g / L or less, or 60 g / L or less. The apparent specific gravity of the silica particles can be determined by filling a container capable of measuring volume, such as a 250 mL graduated cylinder, measuring the filling mass (X g) and filling volume (Y mL) of the silica particles, and dividing the filling mass by the filling volume ([apparent specific gravity (g / L)] = X / Y × 1000).

[0024] Commercially available silica particles include hydrophilic fumed silica such as AEROSIL 50, 90, 130, 200, 200V, 300, and 380 from the AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.), QS-09, QS-10, QS-102, QS-20, QS-20L, QS-30, Q40, and CP-102 from the Reolosil series (manufactured by Tokuyama Corporation), and HDKV15, N20, T30, and T40 from the HDK series (manufactured by Wacker Asahi Kasei Silicone Co., Ltd.), as well as hydrophobic fumed silica such as AEROSIL R972 and R976S from the AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.), and HDK from the HDK series (manufactured by Wacker Asahi Kasei Silicone Co., Ltd.). Examples of suitable silica aerogels include AIRICA (manufactured by Tokuyama Corporation), which is a silica aerogel, such as H15, H20, and H30. The heat insulating layer may contain one type of silica particles or two or more types of silica particles.

[0025] In an embodiment in which the inorganic particles in the insulating material disclosed herein include silica particles, the proportion of silica particles among the inorganic particles is, for example, suitably 30% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more, and may be 85% by mass or more, 90% by mass or more, or even 95% by mass or more. The inorganic particles may be essentially composed of silica particles. Here, "substantially" means that inorganic particles other than silica particles are not contained, at least intentionally, and does not prevent inorganic particles other than silica particles from being unintentionally contained as impurities or crushed particles of other components, etc.

[0026] Inorganic particles (e.g., silica particles) may exist as primary particles, as aggregates formed by aggregation of primary particles, or as aggregates formed by further aggregation of aggregates. In the thermal insulation layer disclosed herein, the inorganic particles may be dispersed in the form of primary particles, aggregates, aggregates, or a combination thereof.

[0027] The average primary particle size of the inorganic particles is not particularly limited and is, for example, about 1 nm to 100 nm, preferably 2 nm or more, more preferably 4 nm or more, and preferably 80 nm or less, more preferably 40 nm or less, even more preferably 30 nm or less, and particularly preferably 20 nm or less. The above average primary particle size range can be applied to various inorganic particles, for example, to the average primary particle size of silica particles when the inorganic particles include silica particles. When fumed silica is included as the silica particles, the average primary particle size of the fumed silica is, for example, about 1 nm to 40 nm, preferably 2 nm or more, more preferably 4 nm or more, and preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 18 nm or less. When silica aerogel is included as the silica particles, the average primary particle size of the silica aerogel is, for example, about 1 nm to 20 nm, preferably 18 nm or less, and more preferably 10 nm or less. When the average primary particle size of the inorganic particles (e.g., silica particles) is within the above range, good thermal insulation properties can be easily ensured. The average primary particle diameter of inorganic particles can be determined using an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Specifically, inorganic particles seen in the electron microscope are randomly selected, their particle diameters are measured, and the average value of these values ​​is calculated. The particle diameter can be determined by measuring the diameter of spherical particles; by measuring the mean value of the short and long axes of ellipsoidal particles seen in the electron microscope; or by measuring the mean value of the short and long axes of irregularly shaped particles.

[0028] When inorganic particles (e.g., silica particles) exist as aggregates of primary particles, the average particle size of the aggregates (hereinafter also referred to as secondary aggregates) is not particularly limited and is, for example, about 0.1 μm to 100 μm, preferably 1 μm or more, more preferably 2 μm or more, and preferably 90 μm or less, more preferably 80 μm or less. The average particle size of secondary aggregates of inorganic particles can be determined by the same methods as for the primary particle size.

[0029] The BET specific surface area of ​​the inorganic particles (e.g., silica particles) is not particularly limited. The BET specific surface area of ​​the inorganic particles is, for example, 40 m ２ / g or more 800m ２ / g or less, and ２ / g or more 600m ２ In some embodiments, the BET specific surface area of ​​the inorganic particles may be about 90 m / g or less. ２ / g or more 380m ２ / g, and preferably less than 130m ２ / g or more, more preferably 175m ２ / g or more, more preferably 200m ２ / g or more, and preferably 350m ２ / g or less, more preferably 320m ２ / g or less, more preferably 300m ２ / g or less. When the BET specific surface area of ​​the inorganic particles is within the above range, good heat insulation properties can be easily ensured even under high temperature and high humidity conditions. The BET specific surface area can be measured by the multipoint nitrogen adsorption method (BET method) in accordance with the International Organization for Standardization ISO 5794 / 1. For example, "AEROSIL 380" manufactured by Aerosil Co., Ltd. has a nominal value of the BET specific surface area of ​​380 m ２ / g, and taking into account the error, it is 350m ２ / g~410m ２ In this case, the nominal value of 380 m ２ / g is considered as the standard.

[0030] The content of inorganic particles (e.g., silica particles) in the heat insulating layer is not particularly limited and may be, for example, in the range of 50% by mass to 99.5% by mass, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less. When the content of inorganic particles is within the above range, good heat insulating properties and mechanical strength can be easily ensured.

[0031] (Inorganic Fibers) The type of inorganic fibers contained in the heat insulating layer is not particularly limited. Examples of inorganic fibers that can be preferably used from the viewpoint of heat resistance and strength include silica fibers, glass fibers, alumina fibers, silica-alumina fibers, silica-alumina-magnesia fibers, biosoluble inorganic fibers, zirconia fibers, alkaline earth silicate fibers, alkaline earth silicate (AES) fibers, glass wool, rock wool, and basalt fibers. The heat insulating layer may contain one type of inorganic fiber or two or more types of inorganic fibers.

[0032] The content of inorganic fibers in the heat insulating layer is not particularly limited and may be, for example, 0.5% by mass to 50% by mass, preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. When the fiber content is within the above range, good thermal resistance is easily ensured and the heat insulating layer is easily manufactured.

[0033] The average fiber length of the inorganic fibers is not particularly limited and may be, for example, 0.05 mm to 50 mm, preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 2 mm or more, and is preferably 25 mm or less, more preferably 13 mm or less, and even more preferably 10 mm or less, and may be 8 mm or less, or may be 6 mm or less. When the average fiber length of the fibers is within the above range, it is easy to produce the heat insulating layer.

[0034] The average fiber diameter of the inorganic fibers is not particularly limited and may be, for example, 0.1 μm to 50 μm, preferably 1 μm or more, more preferably 5 μm or more, even more preferably 7 μm or more, and is preferably 25 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less. When the average fiber diameter of the fibers is within the above range, good thermal insulation properties and mechanical strength can be easily ensured.

[0035] The inorganic fibers preferably contain inorganic fibers having a fiber length of 3 mm or more and less than 35 mm. The proportion of inorganic fibers having a fiber length of 3 mm or more and less than 35 mm to the total number of inorganic fibers is not particularly limited and may be, for example, 30% to 100%, preferably 95% or less, and also preferably 35% or more, more preferably 40% or more, and even more preferably 50% or more. When the content proportion of inorganic fibers having the above fiber length is within the above range, good thermal insulation and mechanical strength are easily ensured.

[0036] The mass ratio of inorganic particles (e.g., silica particles) to inorganic fibers in the heat insulating layer (inorganic particles: inorganic fibers) is not particularly limited and may be, for example, within the range of 40:60 to 99: 1. From the viewpoint of easily ensuring a good balance between good heat insulating properties and mechanical strength, in some embodiments, the mass ratio (inorganic particles: inorganic fibers) is, for example, suitably 45:55 or more, preferably 50:50 or more, more preferably 60:40 or more, even more preferably 70:30 or more, or may be 80:20 or more (e.g., 82:18 or more), or may be, for example, 98:2 or less, preferably 95:5 or less, may be 90:10 or less, or may be 88:12 or less.

[0037] (Dispersant) The heat insulating layer may contain a dispersant as an optional component. For example, when preparing a heat insulating layer using a mixed solution containing inorganic particles and inorganic fibers in a solvent, the dispersant can be useful for improving the ease of preparation of the mixed solution, improving handleability (e.g., improving fluidity), improving dispersion stability (e.g., suppressing viscosity changes over time), and improving moldability. The dispersant is not particularly limited, and a material that can achieve the desired effect can be appropriately selected and used. Dispersants can be classified as 1) polymeric dispersants, 2) surfactant-type dispersants (low molecular weight dispersants), and 3) inorganic dispersants. In some embodiments, non-polymeric dispersants can be preferably used from the viewpoint of suppressing a decrease in the consistency of the mixed solution and suppressing the aggregation of inorganic particles. Here, "non-polymeric" refers to molecules that do not contain polymers (polymers) produced by polymerization reactions in their structure, so-called "low molecular weight compounds." A suitable example of a non-polymeric dispersant is a surfactant. Surfactants are classified into anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. The surfactants can be used alone or in appropriate combinations of two or more. In some embodiments, cationic or nonionic surfactants can be preferably used as dispersants.

[0038] An example of an embodiment in which the use of a dispersant is preferable is one in which silica particles are used as at least a portion of the inorganic particles and a protic solvent is used as the solvent for the mixed solution. For example, in an embodiment in which hydrophilic fumed silica is used as at least a portion of the inorganic particles, the hydrophilic fumed silica and the protic solvent are bonded by hydrogen bonds, which tends to increase the viscosity of the mixed solution. Furthermore, as the specific surface area of ​​inorganic particles (e.g., silica particles such as hydrophilic fumed silica) increases, the area that interacts with the solvent increases, which tends to increase the viscosity of the mixed solution. If the viscosity of the mixed solution becomes excessively high, mixing itself may become difficult, leading to concerns about reduced productivity and reduced quality stability. A dispersant can be used to prevent such phenomena. Furthermore, suppressing an excessive increase in the viscosity of the mixed solution is also preferable from the perspective of preventing damage to the inorganic fibers, etc.

[0039] In some embodiments, one or more compounds represented by the following formula (A1), (A2), (A3), or (A4) can be preferably used as the dispersant.

[0040] In the above formulas (A1) and (A2), R １ , R ２ , R ３ , and R ４ each independently represents a hydrocarbon group which may contain a heteroatom. １ , R ２ , R ３ , and R ４ In addition, two or more of R may be bonded to each other to form a cyclic structure. ５ represents a hydrocarbon group which may contain a heteroatom, and R ６ and R ７ each independently represents a hydrocarbon group which may contain a hetero atom or a hydrogen atom. ５ , R ６ and R ７ In addition, two or more of R may be bonded to each other to form a cyclic structure. ８ and R ９ each independently represents a hydrocarbon group which may contain a heteroatom. ８ and R ９ may be bonded to each other to form a cyclic structure.

[0041] The non-polymeric dispersants represented by formulas (A1), (A2), (A3), and (A4) can generally be considered to be cationic surfactants such as quaternary ammonium salts, amine salts, and pyridinium salts. The non-polymeric dispersants in the heat insulating layer may exist in the form of a salt combined with a counterion, or in the form of a free compound or ion. Examples of such salts include ammonium salts of the dispersant of formula (A1) and a counterion (e.g., chloride ion, bromide ion, ethyl sulfate ion, etc.), and amine salts of the dispersant of formula (A3) and acetic acid. Formulas (A1) to (A4) are described in detail below.

[0042] R in formulas (A1) and (A2) １ , R ２ , R ３ , and R ４ each independently represents a "hydrocarbon group which may contain a heteroatom." The hydrocarbon group is not limited to a linear structure and may have a branched structure, a cyclic structure, a carbon-carbon unsaturated bond (a carbon-carbon double bond, a carbon-carbon triple bond), or the like, and may be any of a saturated hydrocarbon group, an unsaturated hydrocarbon group, an alicyclic saturated hydrocarbon group, an alicyclic unsaturated hydrocarbon group, an aromatic hydrocarbon group, or the like.

[0043] Furthermore, the term "hydrocarbon group which may contain a heteroatom" means that a carbon atom or a hydrogen atom of the hydrocarbon group may be substituted with a heteroatom, or a functional group containing a heteroatom may be formed at the end or inside of the hydrocarbon group. Specific examples of heteroatoms include a nitrogen atom (N), an oxygen atom (O), and a sulfur atom (S), and preferred examples include a nitrogen atom and an oxygen atom. For example, the term "hydrocarbon group which may contain a nitrogen atom" means a hydrocarbon group in which a carbon atom or a hydrogen atom of the hydrocarbon group is substituted with a nitrogen atom, and a primary amino group (-NH ２ The term "hydrocarbon group which may contain an oxygen atom" means that a carbon atom or a hydrogen atom of the hydrocarbon group is substituted with an oxygen atom, and a functional group containing an oxygen atom, such as an ether bond (-O-), a carbonyl group (=O), or a hydroxyl group (-OH), may be formed at the end or inside of the hydrocarbon group. The term "hydrocarbon group which may contain a sulfur atom" means that a carbon atom or a hydrogen atom of the hydrocarbon group is substituted with a sulfur atom, and a functional group containing a sulfur atom, such as a thioether bond (-S-) or a thiol group (-SH), may be formed at the end or inside of the hydrocarbon group. When the hydrocarbon group contains a heteroatom, one hydrocarbon group (for example, R ５The number of heteroatoms contained in one hydrocarbon group may be one or two or more. The upper limit of the number of heteroatoms contained in one hydrocarbon group is not particularly limited. In some embodiments, the number of heteroatoms contained in one hydrocarbon group may be, for example, 10 or less, suitably 6 or less, preferably 5 or less or 4 or less, and more preferably 3 or less or 2 or less. Furthermore, the type of heteroatom contained in one hydrocarbon group may be one type or two or more types.

[0044] Furthermore, R １ , R ２ , R ３ , and R ４ The hydrocarbon groups may be bonded to each other to form a cyclic structure, and examples of "bonded to each other to form a cyclic structure" include the cation in hexadecylpyridinium chloride. This cation is represented by R １ becomes a hexadecyl group, and R ２ and R ３ are bonded to each other to form a cyclic structure. The formed cyclic structure may have a carbon-carbon unsaturated bond. In hexadecylpyridinium chloride, the formed cyclic structure has a carbon-carbon unsaturated bond, and can be considered to form a pyridinium structure.

[0045] R in formulas (A1) and (A2) １ , R ２ , R ３ , and R ４ The total number of carbon atoms (hereinafter sometimes referred to as the "total C number") of the hydrocarbon groups combined is, when considered in terms of the cation of the above-mentioned hexadecylpyridinium chloride, R １ is a hexadecyl group, so it has 16 carbon atoms, and R ２ and R ３ are bonded to each other to form a pyridinium structure, so the number of carbon atoms is 5. Therefore, in the cation of hexadecylpyridinium chloride, R １ , R ２ , R ３ , and R ４The total number of carbon atoms in the combined hydrocarbon groups is 16 + 5 = 21.

[0046] R in formulas (A1) and (A2) １ , R ２ , R ３ , and R ４ The total number of carbon atoms in the combination of these hydrocarbon groups is typically 4 to 40, and is usually suitably 8 or more (e.g., 8 to 40), advantageously 9 or more, and preferably 10 or more (e.g., 11 or more or 12 or more). In some embodiments, the total number of carbon atoms is preferably 13 or more, more preferably 14 or more, even more preferably 15 or more, and preferably 35 or less, more preferably 25 or less, and even more preferably 20 or less. When the total number of carbon atoms is within the above range, the blended liquid can be stabilized in dispersion, and the insulating properties of the insulating material are improved. In some embodiments, the total number of carbon atoms is suitably 18 or less, and may be 16 or less, 14 or less, 13 or less, or 12 or less. Within a range in which appropriate dispersion stability is obtained, it is advantageous for the total number of carbon atoms not to be too high to be advantageous in terms of the fluidity of the blended liquid (e.g., improved fluidity due to increased consistency).

[0047] In some embodiments, R in formulas (A1) and (A2) １ , R ２ , R ３ , and R ４ At least one hydrocarbon group may have 5 to 35 or 6 to 35 (e.g., 8 to 35) carbon atoms. In some embodiments, the number of carbon atoms is preferably 10 or more, more preferably 11 or more, and even more preferably 12 or more, and is preferably 30 or less, more preferably 20 or less, and even more preferably 18 or less, and may be 16 or less, 14 or less, 12 or less, 10 or less, or 9 or less. When the number of carbon atoms is within the above range, the blended liquid tends to be more stably dispersed.

[0048] R in formula (A3) ５ represents a hydrocarbon group, and R ６ and R ７each independently represents a "hydrocarbon group which may contain a heteroatom" or a "hydrogen atom." The hydrocarbon group has the same meaning as the hydrocarbon group in the above formulae (A1) and (A2), and the hydrocarbon groups may be bonded to each other to form a cyclic structure.

[0049] R in formula (A3) ５ , R ６ , and R ７ The total number of carbon atoms (total C number) in the hydrocarbon groups R ５ , R ６ , and R ７ The total number of carbon atoms in the combination of these hydrocarbon groups is typically 3 to 40, and is usually suitably 8 or more (e.g., 8 to 40), advantageously 9 or more, and preferably 10 or more (e.g., 11 or more or 12 or more). In some embodiments, the total number of carbon atoms is preferably 13 or more, more preferably 14 or more, even more preferably 15 or more, and is preferably 35 or less, more preferably 25 or less, and even more preferably 20 or less. When the total number of carbon atoms is within the above range, the blended liquid can be stabilized in dispersion, and the insulating properties of the insulating material are improved. In some embodiments, the total number of carbon atoms is suitably 18 or less, and may be 16 or less, 14 or less, 13 or less, or 12 or less. Within a range in which appropriate dispersion stability is obtained, it is advantageous for the total number of carbon atoms not to be too high to be advantageous in terms of the fluidity of the blended liquid (e.g., improved fluidity due to increased consistency).

[0050] In some embodiments, R in formula (A3) ５ , R ６ , and R ７ At least one hydrocarbon group has 6 to 35 carbon atoms (e.g., 8 to 35), preferably 10 or more, more preferably 11 or more, and even more preferably 12 or more, and preferably 30 or less, more preferably 20 or less, and even more preferably 18 or less. When the number of carbon atoms is within the above range, the blended liquid tends to be more stably dispersed.

[0051] R in formula (A4) ８ and R ９each independently represents a "hydrocarbon group which may contain a heteroatom." The hydrocarbon group has the same meaning as the hydrocarbon group in the above formulae (A1) and (A2), and the hydrocarbon groups may be bonded to each other to form a cyclic structure.

[0052] R in formula (A4) ８ and R ９ The total number of carbon atoms (total C number) combining the above hydrocarbon groups is typically 2 to 40, and is usually suitably 8 or more (e.g., 8 to 40), advantageously 9 or more, and preferably 10 or more (e.g., 11 or more or 12 or more). In some embodiments, the total number of carbon atoms is preferably 13 or more, more preferably 14 or more, even more preferably 15 or more, and is preferably 35 or less, more preferably 25 or less, and even more preferably 20 or less. When the total number of carbon atoms is within the above range, the blended liquid can be stabilized in dispersion, and the insulating properties of the insulating material are improved. In some embodiments, the total number of carbon atoms is suitably 18 or less, and may be 16 or less, 14 or less, 13 or less, or 12 or less. Within a range in which appropriate dispersion stability is obtained, it is advantageous for the total number of carbon atoms not to be too high to improve the fluidity of the blended liquid (e.g., improving fluidity by increasing consistency).

[0053] In some embodiments, R in formula (A4) ８ and R ９ At least one hydrocarbon group typically has 7 to 35 (e.g., 8 to 35) carbon atoms, preferably 10 or more, more preferably 11 or more, and even more preferably 12 or more, and preferably 30 or less, more preferably 20 or less, and even more preferably 18 or less. When the number of carbon atoms is within the above range, the blended liquid tends to be more stably dispersed.

[0054] Specific examples of the salt of the non-polymeric dispersant represented by formula (A1) include nonyltrimethylammonium chloride, nonyltrimethylammonium bromide, decyltrimethylammonium chloride, decyltrimethylammonium bromide, undecyltrimethylammonium chloride, undecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, tridecyltrimethylammonium chloride, tridecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, pentadecyltrimethylammonium chloride, pentadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, heptadecyltrimethylammonium chloride, heptadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and octadecyltrimethylammonium bromide. Examples of suitable ammonium salts include octadecyltrimethylammonium, nonadecyltrimethylammonium chloride, nonadecyltrimethylammonium bromide, icosyltrimethylammonium chloride, icosyltrimethylammonium bromide, henicosyltrimethylammonium chloride, henicosyltrimethylammonium bromide, docosyltrimethylammonium chloride, docosyltrimethylammonium bromide, tricosyltrimethylammonium chloride, tricosyltrimethylammonium bromide, tetracosyltrimethylammonium chloride, tetracosyltrimethylammonium bromide, pentacosyltrimethylammonium chloride, pentacosyltrimethylammonium bromide, hexacosyltrimethylammonium chloride, hexacosyltrimethylammonium bromide, heptacosyltrimethylammonium chloride, heptacosyltrimethylammonium bromide, and dioctadecyldimethylammonium chloride.Other examples of the salt of the non-polymeric dispersant represented by formula (A1) include pentyltrimethylammonium chloride (8 total carbon atoms), pentyltrimethylammonium bromide, hexyltrimethylammonium chloride (9 total carbon atoms), hexyltrimethylammonium bromide, heptyltrimethylammonium chloride (10 total carbon atoms), heptyltrimethylammonium bromide, octyltrimethylammonium chloride (11 total carbon atoms), octyltrimethylammonium bromide, dibutyldimethylammonium chloride (10 total carbon atoms), dibutyldimethylammonium bromide, dihexyldimethylammonium chloride (14 total carbon atoms), dihexyldimethylammonium bromide, dioctyldimethylammonium chloride (18 total carbon atoms), dioctyldimethylammonium bromide, didecyldimethylammonium chloride (22 total carbon atoms), didecyldimethylammonium bromide, octyldimethylethylammonium ethyl sulfate (12 total carbon atoms), and the like.

[0055] Specific examples of the salt of the non-polymeric dispersant represented by formula (A2) include dodecylpyridinium chloride, dodecylpyridinium bromide, hexadecylpyridinium chloride, hexadecylpyridinium bromide, and (1-hexadecyl-4-methylpyridinium chloride).

[0056] Examples of the non-polymeric dispersant represented by formula (A3) include non-polymeric dispersants represented by the following formula (A3-1), (A3-2), or (A3-3).

[0057] (In formula (A3-1), R ５ represents a hydrocarbon group which may contain a heteroatom (e.g., a nitrogen atom), and R ５ has 8 to 40 (e.g., 8 to 35) carbon atoms. ５ represents a hydrocarbon group which may contain a heteroatom (e.g., a nitrogen atom), and R ５ has 6 to 38 (e.g., 7 to 35) carbon atoms. ５ and R １１ each independently represents a hydrocarbon group which may contain a heteroatom (for example, a nitrogen atom), and j represents an integer of 0 to 5.５ and R １１ The total number of carbon atoms in the hydrocarbon groups combined is 3 to 35 (e.g., 7 to 35).

[0058] Specific examples of the non-polymeric dispersant represented by formula (A3) include dodecylamine, dodecyldimethylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, hexadecyldimethylamine, heptadecylamine, octadecylamine, nonadecylamine, icosylamine, henicosylamine, docosylamine, tricosylamine, tetracosylamine, pentacosylamine, hexacosylamine, heptacosylamine, and N-dodecylpiperidine. Other examples of the non-polymeric dispersant represented by formula (A3) include hexyldimethylamine, heptyldimethylamine, octylamine, octyldimethylamine, nonylamine, nonyldimethylamine, decylamine, decyldimethylamine, and undecylamine. Still other examples of the non-polymeric dispersant represented by formula (A3) include R ５ , R ６ , R ７ and a non-polymeric dispersant in which at least one of the groups is a hydrocarbon group containing a heteroatom (for example, a hydrocarbon group having an ether bond and / or a hydroxy group). A specific example of such a non-polymeric dispersant is stearyl propylene glycol dimethylamine (C １８ H ３７ OCH ２ CH(OH)CH ２ N (CH ３ ) ２ ) are listed.

[0059] Specific examples of the non-polymeric dispersant represented by formula (A4) include 4-dodecylpyridine, 2-methyl-4-tridecylpyridine, 2-tetradecylpyridine, and 4-pentadecylpyridine.

[0060] The content of the dispersant (e.g., a non-polymeric dispersant) in the heat insulating layer is not particularly limited. The content of the dispersant is typically greater than 0% by mass, and may be, for example, 0.0001% by mass or more, 0.0005% by mass or more, 0.001% by mass or more, or 0.05% by mass or more. The content of the dispersant in the heat insulating layer may be, for example, 7% by mass or less, and is usually 5% by mass or less (e.g., 0.0001% by mass or more and 5% by mass or less) from the viewpoint of easily suppressing the influence on other properties. In some embodiments, the content of the dispersant in the thermal insulation layer is, for example, about 0.01% to 5% by mass, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, particularly preferably 0.5% by mass or less, and may be 0.3% by mass or less, 0.1% by mass or less, 0.05% by mass or less, 0.01% by mass or less, 0.005% by mass or less, 0.001% by mass or less, or 0.0005% by mass or less. Note that, depending on the manufacturing method of the thermal insulation material, the amount of dispersant relative to the amount of inorganic particles (relative amount by mass) may differ between the amount of dispersant used during manufacturing and the amount of dispersant contained in the resulting thermal insulation material. This is because, for example, when a mixed solution containing inorganic particles, inorganic fibers, and a dispersant is applied to a solvent, the coating is compression-molded to a desired thickness, and then dried to produce a thermal insulation layer, if some of the dispersant contained in the mixed solution is washed away with the solvent during compression molding, the amount of dispersant contained in the resulting thermal insulation material will decrease. The dispersant contained in the thermal insulation layer can be considered to be the remaining amount of dispersant used during the production of the thermal insulation material. The content of dispersant in the thermal insulation layer can be determined by extracting the dispersant from the thermal insulation layer using an appropriate solvent (a solvent capable of dissolving the target dispersant) and performing quantitative analysis using a known method. The type of dispersant contained in the thermal insulation layer can be determined by extracting the dispersant from the thermal insulation layer using an appropriate solvent as described above, and identifying the dispersant contained in the resulting extract using a known method.

[0061] (Other Components) The heat insulating layer may further contain other components in addition to the inorganic particles and inorganic fibers described above, and the dispersant described above as an optional component. Specific examples of such other components include binders (binding agents), organic fibers, and the like. When the heat insulating layer contains a binder, the type of binder is not particularly limited, but specific examples include thermoplastic resins, thermosetting resins, sugars, and the like. The heat insulating layer may contain one type of binder, or may contain two or more types of binders. By containing the above binder, shape stability is improved.

[0062] When the heat insulating layer contains a binder, the type of binder is not particularly limited. The binder may be an organic binder or an inorganic binder. Specific examples of organic binders include thermoplastic resins, thermoplastic elastomers, thermosetting resins, thermosetting elastomers, sugars, water-soluble polymers, etc. Specific examples of inorganic binders include aluminum oxide, zirconium oxide, magnesium oxide, titanium oxide, calcium oxide, etc. The binder can help improve the shape stability of the heat insulating layer. The heat insulating layer may contain one type of binder or two or more types of binders. Alternatively, the heat insulating layer may be substantially free of binders.

[0063] When the heat insulating layer contains a binder, the content of the binder is not particularly limited and may be, for example, 0.01% by mass to 10% by mass of the heat insulating layer, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. When the binder content is within the above range, the heat insulating layer is likely to have both good heat insulating properties and good shape stability.

[0064] The insulating layer may contain organic fibers in addition to inorganic fibers. Specific examples of organic fibers include felts made of cellulose fiber, polyester, polypropylene, etc. The use of organic fibers can be advantageous from the viewpoints of improving cushioning properties and durability against repeated pressure fatigue. The content of organic fibers in the insulating layer can be appropriately set to obtain the desired usage effect, and may be, for example, more than 0 parts by mass, 1 part by mass or more, 4 parts by mass or more, 8 parts by mass or more, or 16 parts by mass or more per 100 parts by mass of inorganic fibers. On the other hand, in some embodiments, from the viewpoint of heat resistance, etc., the content of organic fibers in the insulating layer is suitably less than 100 parts by mass per 100 parts by mass of inorganic fibers, advantageously less than 50 parts by mass, and may be less than 20 parts by mass, less than 10 parts by mass, less than 5 parts by mass, or less than 1 part by mass. The insulating material may also be free of organic fibers.

[0065] (Properties of the Heat Insulating Layer, etc.) The thickness of the heat insulating layer is not particularly limited and may be, for example, approximately 0.3 mm to 10 mm, preferably 0.5 mm or more, and may be 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, or 1.0 mm or more. From the viewpoint of heat insulating performance and insulation performance, a thicker heat insulating layer is advantageous. In some embodiments, the thickness of the heat insulating layer may be, for example, 1.2 mm or more, 1.5 mm or more, or 2 mm or more. In some embodiments, the thickness of the heat insulating layer may be, for example, 9 mm or less, preferably 7 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less, and may be less than 2 mm, less than 1.5 mm, 1.3 mm or less, or 1.0 mm or less, or less than 1.0 mm. By reducing the thickness of the heat insulating layer, it is possible to reduce the thickness and weight of the heat insulating material. The thickness of the insulating layer can be determined by measuring the cross section of the insulating layer at several points (e.g., 10 points) using a thickness measuring device (e.g., Ozaki Seisakusho's digital thickness gauge JAN-257 (measuring probe Φ20 mm)).

[0066] The density of the heat insulating layer is not particularly limited, and may be, for example, 0.2 to 0.5 g / cm ３In some embodiments, the density of the insulating layer is preferably 0.3 g / cm ３ More preferably, 0.35 g / cm ３ More preferably, 0.37 g / cm ３ or more, and preferably 0.45 g / cm ３ The following is the result.

[0067] The number of insulating layers included in the thermal insulation material disclosed herein is not particularly limited, as long as it is at least 1. From the viewpoint of ease of manufacturing the thermal insulation material and thinning, in some embodiments, the number of insulating layers is suitably 10 or less, preferably 7 or less, more preferably 5 or less, and may be 3 or less, 2 or less, or even 1.

[0068] The heat insulating layer may be bonded to the adjacent layer with an adhesive or pressure-sensitive adhesive, or may not be bonded to the adjacent layer. In some embodiments, it is preferable that the heat insulating layer is not bonded to the adjacent layer with an adhesive or pressure-sensitive adhesive. By not using an adhesive or pressure-sensitive adhesive, that is, by not using an adhesive or pressure-sensitive adhesive, the thermal conductivity can be reduced compared to when an adhesive or pressure-sensitive adhesive is used.

[0069] The shape of the heat insulating layer is not particularly limited. In some embodiments, the shape of the heat insulating layer when viewed from above may be, for example, a polygon such as a quadrangle, a circle, an ellipse, etc. Examples of quadrangles include rectangles (including squares and rectangles).

[0070] (Insulating properties of the thermal insulation layer) In the technology disclosed herein, the breakdown voltage of the thermal insulation layer in a hygroscopic state (hygroscopic breakdown voltage) is not particularly limited. In some embodiments, the hygroscopic breakdown voltage of the thermal insulation layer is suitably, for example, higher than 1.20 kV / mm, and preferably 1.25 kV / mm or higher. A high hygroscopic breakdown voltage of the thermal insulation layer means that it has good insulating performance (short-circuit prevention performance) even in a hygroscopic state. Such a thermal insulation layer and a thermal insulation material including the thermal insulation layer are preferred from the viewpoint of insulation reliability against environmental changes. From the viewpoint of improving the insulation reliability, in some embodiments, the hygroscopic breakdown voltage of the thermal insulation layer is advantageously 1.30 kV / mm or higher, preferably 1.40 kV / mm or higher, more preferably 1.50 kV / mm or higher (e.g., greater than 1.50 kV / mm), and even more preferably 1.60 kV / mm or higher, and may be, for example, 1.70 kV / mm or higher, 1.80 kV / mm or higher, or 1.85 kV / mm or higher. The upper limit of the moisture-absorbed breakdown voltage is not particularly limited. In some embodiments, from the viewpoint of the availability and cost of the materials used to manufacture the thermal insulation layer, or taking into account the balance with other properties such as thermal insulation properties and compressibility, the moisture-absorbed breakdown voltage of the thermal insulation layer may be, for example, approximately 4.00 kV / mm or less, 3.00 kV / mm or less, 2.50 kV / mm or less, 2.00 kV / mm or less, less than 1.90 kV / mm, or less than 1.70 kV / mm. The moisture-absorbed breakdown voltage of the thermal insulation layer is measured using the thermal insulation layer after being left to stand in an environment of 85 ° C and 85% RH for 72 hours to absorb moisture, more specifically, it is measured by the method described in the Examples below.

[0071] (Electrical conductivity of extracted water E Ｓ In the technology disclosed herein, the electrical conductivity E of the extracted water obtained by heating and extracting 1.0 g of the heat insulating layer with 50 g of ultrapure water is Ｓ In some embodiments, the upper limit of the electrical conductivity E Ｓmay be, for example, approximately 75 μS / cm or less, advantageously 70 μS / cm or less, preferably 60 μS / cm or less, more preferably 50 μS / cm or less or 40 μS / cm or less, and even more preferably 35 μS / cm or less or 30 μS / cm or less (e.g., less than 30 μS / cm).

[0072] Electrical conductivity of extracted water E Ｓ A thermal insulation layer with a lower value generally tends to exhibit a higher breakdown voltage upon moisture absorption. The reason for this, although not intended to be limited to, is that ionic impurities contained in the thermal insulation layer have a higher electrical conductivity than the electrical conductivity E Ｓ At least a part of the ionic impurities may be derived from a solvent (e.g., a protic solvent such as water) used in preparing a mixed solution containing inorganic particles and inorganic fibers in the manufacturing process of the thermal insulation layer. Ionic impurities derived from the solvent remain (adhere) in the thermal insulation layer formed by drying the mixed solution, and the ionic impurities flow out (elute) from the thermal insulation material by hot water extraction and increase the electrical conductivity E of the extracted water. Ｓ The presence of the ionic impurities in the heat insulating layer can increase the moisture absorption amount of the heat insulating layer, which can in turn increase the breakdown voltage during moisture absorption. Furthermore, in a heat insulating layer with a relatively high content of ionic impurities, when the heat insulating layer is exposed to a high humidity environment or comes into contact with liquid water (for example, water produced by condensation of moisture in the environment), there is a concern that the ionic impurities will be partially concentrated or precipitated in areas, which may trigger a short circuit and reduce the insulation performance. According to the technology disclosed herein, the electrical conductivity E of the extracted water can be increased by 100%. Ｓ By limiting the electrical conductivity E of the extracted water Ｓ By controlling the content of impurities that increase the breakdown voltage, a heat insulating material with high insulation reliability can be obtained even when moisture is absorbed. For example, it is possible to preferably achieve a breakdown voltage when moisture is absorbed that satisfies any combination of the upper and lower limits described above.

[0073] The electrical conductivity E ＳIn some embodiments, the lower limit of the electrical conductivity E is set to 0.05 μS / cm or more, for example, 3 μS / cm or more, 5 μS / cm or more, or 8 μS / cm or more, taking into consideration the availability and cost of the material used to manufacture the thermal insulation layer, or the balance with other properties such as thermal insulation properties and compressibility properties. Ｓ The electrical conductivity E of the extracted water of the heat insulating layer may be, for example, 10 μS / cm or more, 13 μS / cm or more, 15 μS / cm or more, 18 μS / cm or more, or 20 μS / cm or more. Ｓ The electrical conductivity E can be determined by measuring the electrical conductivity of the extracted water obtained by heating and extracting 1.0 g of the heat insulating layer with 50 g of ultrapure water. Ｓ More specifically, it is measured by the method described in the Examples below.

[0074] (Moisture absorption amount of the heat insulating layer) In the technology disclosed herein, the moisture absorption amount of the heat insulating layer, calculated by the following formula: Moisture absorption amount [%] = ((W1 - W0) / W0) × 100, is not particularly limited. In the above formula, W0 represents the mass of the heat insulating material in its normal state. In the above formula, W1 represents the mass of the heat insulating material after it has been left to stand in an environment of 85°C and 85% RH for 72 hours (mass after absorbing moisture). More specifically, the mass at normal state W0 and the mass after absorbing moisture W1 are measured by the methods described in the examples below.

[0075] In some embodiments, the moisture absorption of the insulating layer is preferably less than 3.5%, and more preferably 3.3% or less. Insulating layers that satisfy the above moisture absorption requirements generally tend to exhibit good insulation performance even in a hygroscopic state. Such insulating layers facilitate the production of insulating materials with good insulation reliability against environmental changes. The moisture absorption of the insulating material in the technology disclosed herein may be, for example, 3.0% or less or less than 3.0%, 2.8% or less, 2.5% or less, 2.2% or less, or 2.0% or less or less than 2.0%. The lower limit of the moisture absorption of the insulating layer is not particularly limited, but is typically greater than 0.0%. In some embodiments, the moisture absorption of the insulating layer may be, for example, 0.3% or more, 0.5% or more, 0.7% or more, or 1.0% or more, taking into account the availability and cost of materials used to manufacture the insulating layer, or the balance with other properties such as insulating properties and compressibility.

[0076] (Thermal properties of the insulating layer) The thermal conductivity of the insulating layer at 80°C and a pressure of 2 MPa is preferably 0.010 W / K·m or more, and preferably 0.3 W / K·m or less, more preferably 0.1 W / K·m or less, more preferably 0.08 W / K·m or less, more preferably 0.06 W / K·m or less, more preferably 0.055 W / K·m or less, more preferably 0.045 W / K·m or less, and even more preferably 0.04 W / K·m or less.

[0077] The thermal conductivity of the insulating layer at 600°C and 2 MPa pressure is preferably 0.010 W / K·m or more, and preferably 0.3 W / K·m or less, more preferably 0.2 W / K·m or less, more preferably 0.1 W / K·m or less, more preferably 0.08 W / K·m or less, and even more preferably 0.075 W / K·m or less.

[0078] When the thickness (initial thickness) of the heat insulating layer is adjusted to 2 mm without pressure, the heat resistance at 80°C and 2 MPa pressure is preferably 0.020 (K·m ２ ) / W or more, more preferably 0.025 (K m ２ ) / W or more, more preferably 0.03 (K m２ ) / W or more, more preferably 0.035 (K·m ２ ) / W or more, and preferably 0.1 (K m ２ The thermal resistance of the heat insulating layer having an initial thickness of 2 mm at 600°C and a pressure of 2 MPa is preferably 0.010 (K·m ２ ) / W or more, more preferably 0.015 (K·m ２ ) / W or more, more preferably 0.020 (K·m ２ ) / W or more, and preferably 0.1 (K m ２ ) / W or less.

[0079] The thermal conductivity of the heat insulating layer can be measured by the method described in Japanese Industrial Standards JIS A 1412-2:1999 "Method for measuring thermal resistance and thermal conductivity of thermal insulating materials - Part 2: Heat flow meter method (HFM method)."

[0080] The heat flow meter method (HFM method) is a secondary measurement method or comparative measurement method that measures heat transfer characteristics such as thermal conductivity and thermal resistance by comparing a flat thermal insulation material (heat insulating layer) as a test specimen with a standard plate. The detailed measurement procedure and measurement conditions are explained below.

[0081] The insulation layer is cut to a predetermined size (e.g., 20 mm x 20 mm) to prepare a test specimen, and an alumina composite material ("RS-100", manufactured by ZIRCAR Refractory Composites, Inc., thickness: 5 mm, thermal conductivity: 0.66 W / K m) or the like is prepared as a standard plate. Next, the first thermocouple, titanium plate, insulation layer, titanium plate, second thermocouple, standard plate, and third thermocouple are placed on the lower plate of a pneumatic press in this order from top to bottom, and the test specimen, standard plate, thermocouple, etc. are tightly attached between the upper and lower plates. The upper and lower plates are then heated to their respective predetermined measurement temperatures, and a load is applied to the test specimen, etc. using the pneumatic press to achieve the predetermined measurement pressure.

[0082] The measurement temperatures may be, for example, 80° C. for the upper plate on the first thermocouple side and 30° C. for the lower plate on the third thermocouple side. On the other hand, the measurement temperatures under high temperature conditions may be, for example, 600° C. for the upper plate on the first thermocouple side and 40° C. for the lower plate on the third thermocouple side.

[0083] The measurement pressure can be, for example, 2 MPa (load: 800 N). Measurement is continued under heating and pressure until the detected temperature of each thermocouple stabilizes. The thermal conductivity k1 of the thermal insulating layer can be calculated from the detected temperature of each thermocouple after the temperature stabilizes, the thickness of the thermal insulating layer under pressure, the thermal conductivity of the standard plate, and the thickness of the standard plate under pressure using the following formula (I): k1 = k2 × (L1 × ΔT1) / (L2 × ΔT2) (I) (where k1 is the thermal conductivity of the thermal insulating layer [W / (m K)], k2 is the thermal conductivity of the standard plate [W / (m K)], L1 is the thickness of the thermal insulating layer under pressure, L2 is the thickness of the standard plate, ΔT1 is the temperature difference between the temperatures of the second thermocouple and the third thermocouple, and ΔT2 is the temperature difference between the temperatures of the first thermocouple and the second thermocouple.)

[0084] The detected temperature being stabilized may mean that the temperature change after about 10 minutes has passed falls within a predetermined range (for example, within ±0.1° C.).

[0085] The thermal resistance of the heat insulating layer can be calculated from the above-mentioned thermal conductivity k1 and thickness under pressure L1 by the following formula (II): R1 = L1 / k1 (II) (where R1 is the thermal resistance [(m ２ K) / W], k1 is the thermal conductivity of the heat insulating layer [W / (m K)], and L1 is the thickness of the heat insulating layer when pressed.

[0086] (Compression Characteristics of the Insulating Layer) The compression characteristics of the insulating layer are not particularly limited and can be appropriately selected depending on the application and mode of use. In some embodiments, the 2 MPa compressive deformation rate of the insulating layer can be, for example, within a range of 5% to 50%. The 2 MPa compressive deformation rate of the insulating layer is measured as the compressive strain [%] when the compressive stress reaches 2 MPa in a compression test in which the insulating layer is compressed in the thickness direction, and more specifically, is measured by the method described in the Examples below. By having the 2 MPa compressive deformation rate of the insulating layer within an appropriate range, for example, in an insulating material disposed between cells of a lithium-ion battery module, battery expansion (e.g., expansion associated with cell charging) can be appropriately buffered. In some embodiments, the 2 MPa compressive deformation rate is preferably 10% or more, more preferably 15% or more, and also preferably 35% or less, more preferably 30% or less, and even more preferably 25% or less (e.g., 23% or less).

[0087] In some embodiments, the preferred range of compressive stress when the compressive strain of the insulating layer is 25%, 50%, or 70% is a density of 300 kg / m ３ In the case of the above high density heat insulating layer (hereinafter abbreviated as "high density heat insulating layer"), and the case of the density of 300 kg / m ３ The compressive stress can be measured in the same manner as for the buffer layer described later.

[0088] The compressive stress (the value [MPa] obtained by dividing the compressive force [N] by the initial cross-sectional area of ​​the test specimen) when the compressive strain of the high-density insulating layer is 25% is, for example, about 1 MPa to 5 MPa, preferably 1.3 MPa or more, more preferably 1.7 MPa or more, even more preferably 2.0 MPa or more, and preferably 4.5 MPa or less, more preferably 4.0 MPa or less, even more preferably 3.5 MPa or less.

[0089] The compressive stress when the compressive strain of the high-density insulating layer is 50% is, for example, about 4.0 MPa to 15 MPa, preferably 5.0 MPa or more, more preferably 6.0 MPa or more, even more preferably 7.0 MPa or more, and preferably 13 MPa or less, more preferably 11 MPa or less, even more preferably 9.0 MPa or less.

[0090] The compressive stress when the compressive strain of the high-density insulating layer is 70% is, for example, about 10 MPa to 25 MPa, preferably 11 MPa or more, more preferably 12 MPa or more, even more preferably 13 MPa or more, and preferably 23 MPa or less, more preferably 21 MPa or less, even more preferably 19 MPa or less.

[0091] The compressive stress when the compressive strain of the low-density insulating layer is 25% is, for example, about 0.05 MPa to 1.0 MPa, preferably 0.1 MPa or more, more preferably 0.15 MPa or more, even more preferably 0.20 MPa or more, and preferably 0.7 MPa or less, more preferably 0.5 MPa or less, even more preferably 0.3 MPa or less.

[0092] The compressive stress when the compressive strain of the low-density insulating layer is 50% is, for example, 1.0 MPa to 4.0 MPa, preferably 1.3 MPa or more, more preferably 1.5 MPa or more, even more preferably 1.7 MPa or more, and preferably 3.5 MPa or less, more preferably 3.0 MPa or less, even more preferably 2.5 MPa or less.

[0093] The compressive stress when the compressive strain of the low-density insulating layer is 70% is, for example, about 4.0 MPa to 10 MPa, preferably 4.5 MPa or more, more preferably 5.0 MPa or more, even more preferably 5.5 MPa or more, and preferably 9.0 MPa or less, more preferably 8.0 MPa or less, even more preferably 7.0 MPa or less.

[0094] <Preparation of Heat Insulating Layer> The method for preparing the heat insulating layer disclosed herein is not particularly limited, and the layer can be prepared by appropriately employing known processes. For example, a mixture containing inorganic particles and inorganic fibers and other optional components (such as a dispersant) that may be used as needed can be prepared by a known mixing method such as a wet method or a dry method, and the mixture can be used to prepare a heat insulating layer. Examples of methods for preparing a heat insulating layer that include preparing the mixture (typically a slurry-like mixed liquid) by a wet method include methods that include the following steps: Mixing step: A step of mixing inorganic particles, inorganic fibers, and other optional components (such as a dispersant) that may be used as needed in a solvent to obtain a mixed liquid. Coating step: A step of applying the mixed liquid to obtain a coating film. Molding step: A step of molding the coating film to obtain a heat insulating layer.

[0095] The mixing in the mixing step can be carried out using, for example, a Disper, a Laboplastomill, a Trimix, a planetary mixer, a kneader, or the like.

[0096] The type of solvent is not particularly limited. For example, a solvent selected from protic solvents such as alcohols (e.g., alcohols having about 1 to 4 carbon atoms, such as methanol, ethanol, isopropyl alcohol, and ethylene glycol), amides, and water, and aprotic solvents such as esters, ketones, nitriles, and ethers can be used. A mixed solvent containing two or more solvents may also be used.

[0097] The surface tension of the solvent is not particularly limited and is, for example, 20 mN / m to 73 mN / m, preferably 21 mN / m or more, and preferably 50 mN / m or less, more preferably 40 mN / m or less, and even more preferably 30 mN / m or less. When the surface tension of the solvent is within the above range, the heat insulating properties and mechanical strength are improved. The above-mentioned range of surface normal force can also be applied to the surface tension of a mixed solvent. The surface tension of a solvent (which may be a mixed solvent) can be measured by the ring method. Note that the surface tension of a mixed solvent obtained by mixing the protic solvent isopropyl alcohol (surface tension: 21 mN / m) and water (surface tension: 73 mN / m) in a mass ratio of 5:1 is approximately 23 mN / m.

[0098] When using the above-mentioned dispersant (preferably a non-polymeric dispersant), the amount of dispersant to be mixed into the mixed solution in the mixing step is not particularly limited and can be appropriately set in consideration of the balance between the use effect and the influence on other properties. The amount of dispersant to be mixed in the mixed solution may be, for example, 0.0001 parts by mass or more, based on the amount of the active ingredient of the dispersant, relative to 100 parts by mass of the inorganic particles (e.g., silica particles) contained in the mixed solution. From the viewpoint of easily obtaining a higher use effect, it may be 0.0005 parts by mass or more, 0.001 parts by mass or more, 0.05 parts by mass or more, or for example, 10 parts by mass or less. From the viewpoint of easily avoiding the influence on other properties, it is usually appropriate that it is 5 parts by mass or less (e.g., 0.0001 parts by mass or more and 5 parts by mass or less), advantageously 3 parts by mass or less, may be 2 parts by mass or less, 1 part by mass or less, or less than 1 part by mass (e.g., 0.8 parts by mass or less). In some embodiments, the amount of dispersant in the mixed solution is suitably, for example, 0.05 to 5 parts by mass, preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 2 parts by mass or less, based on the amount of the active ingredient of the dispersant per 100 parts by mass of the inorganic particles (e.g., silica particles) contained in the mixed solution. When the amount of dispersant in the mixed solution is within the above range, the dispersibility of the mixed solution is stable, and a heat insulating layer with good heat insulating properties is likely to be obtained.

[0099] In embodiments in which water is used as at least a portion of the solvent in the mixed solution, the type and quality of the water (hereinafter also referred to as "production water") are not particularly limited and can be selected taking into consideration availability, cost, and the like. In addition to purified water such as distilled water, ultrapure water, reverse osmosis water (RO water), and ion-exchanged water (deionized water), tap water, softened water, industrial water, recycled water, and various types of water such as groundwater, spring water, river water, and rainwater can be selected, provided that they do not significantly impair the performance of the heat insulating layer (e.g., insulating performance such as breakdown voltage upon moisture absorption) or cause inconvenience in the production process (e.g., a significant decrease in the consistency of the mixed solution over time). These waters can be used after appropriate treatment, such as filtration, as necessary.

[0100] In some embodiments, the electrical conductivity E of the water used to produce the thermal insulation layer Ｍ is suitably, for example, 8000 μS / cm or less, advantageously 6000 μS / cm or less, preferably 4000 μS / cm or less, more preferably 2000 μS / cm or less, and even more preferably 1000 μS / cm or less or less than 1000 μS / cm. Ｍ is, for example, 800 μS / cm or less, preferably 600 μS / cm or less, more preferably 400 μS / cm or less, and even more preferably 300 μS / cm or less, and may be 250 μS / cm or less, 200 μS / cm or less, 150 μS / cm or less, 100 μS / cm or less, 80 μS / cm or less, 60 μS / cm or less, 40 μS / cm or less, 20 μS / cm or less, 10 μS / cm or less, or 5 μS / cm. Ｍ is not particularly limited, and is suitably, for example, 1 μS / cm or more, and may be 2 μS / cm or more, 5 μS / cm or more, 15 μS / cm or more, 30 μS / cm or more, or 50 μS / cm or more, or may be 70 μS / cm or more, 90 μS / cm or more, 120 μS / cm or more, 170 μS / cm or more, or 240 μS / cm or more. Ｍ can be used as a guide to determine the amount of ionic compounds (typically, ionic metal compounds) contained in the manufacturing water. Usually, at least a portion of the ionic compounds in the manufacturing water remains in the heat insulating layer obtained from the mixed solution prepared using the manufacturing water, and therefore, the electrical conductivity E Ｍ By selecting the quality of the production water using the above, it is possible to control within a practical range the effect of the production water quality on the performance of the heat insulating layer (for example, insulation performance such as dielectric breakdown voltage upon moisture absorption) and the effect on the properties of the mixed liquid (for example, flow properties such as consistency and their stability over time).

[0101] The mixing temperature when preparing the mixture is not particularly limited, but is usually from 20° C. to the boiling point of the solvent, preferably 22° C. or higher, and preferably 50° C. or lower, more preferably 40° C. or lower, and even more preferably 30° C. or lower. When the mixing temperature is within the above range, the solvent (e.g., organic solvent) is less likely to volatilize, and the blending ratio is less likely to change.

[0102] The mixing time is not particularly limited and is, for example, 1 minute to 5 hours, preferably 5 minutes or more, and preferably 4 hours or less, more preferably 2 hours or less, and even more preferably 1 hour or less. When the mixing time is within the above range, the heat insulating layer can be produced efficiently.

[0103] The consistency (initial consistency) of the mixed liquid is not particularly limited, but can be, for example, within a range of about 50 to 250. In some embodiments, the initial consistency of the mixed liquid is, for example, 55 or more, 60 or more, or 65 or more, preferably 70 or more, more preferably 75 or more, even more preferably 80 or more, and particularly preferably 85 or more (e.g., 90 or more). It is preferable that the initial consistency of the mixed liquid is not too low from the viewpoint of reducing fiber breakage of the inorganic fibers during preparation, stirring, feeding, application, etc. of the mixed liquid. When the consistency of the mixed liquid is within the above range, fiber breakage can be reduced when the fibers are uniformly dispersed. Furthermore, in some embodiments, the initial consistency of the mixed liquid is preferably 240 or less, more preferably 230 or less, and even more preferably 220 or less (e.g., 210 or less or 200 or less). Having an initial consistency of the mixed liquid that is not too high can be advantageous from the viewpoints of uniform dispersion of the inorganic fibers, moldability when molding the mixed liquid to obtain a thermal insulation layer, and shape accuracy of the molded product (thermal insulation layer).

[0104] The consistency of the mixed solution 24 hours after preparation (24-hour consistency) is not particularly limited and can be, for example, within a range of about 50 to 200. In some embodiments, the 24-hour consistency of the mixed solution is, for example, 55 or more, 60 or more, or 65 or more, preferably 70 or more, more preferably 75 or more, even more preferably 80 or more, and particularly preferably 85 or more (e.g., 90 or more). In some embodiments, the initial consistency of the mixed solution is preferably 240 or less, more preferably 230 or less, and even more preferably 220 or less (e.g., 210 or less or 200 or less). Having the 24-hour consistency of the mixed solution within the above range increases the degree of freedom in setting the time from preparation of the mixed solution to application, which is preferable from the perspective of production management.

[0105] In some embodiments, the consistency reduction rate calculated from the initial consistency V0 and the 24-hour consistency V1 according to the following formula: consistency reduction rate [%] = (V0 - V1) / V0 × 100 is suitably 50% or less, advantageously 40% or less, preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less (e.g., less than 20%, 15% or less, or 10% or less). Furthermore, the consistency reduction rate is suitably -20% or more, preferably -10% or more, and more preferably 0% or more. Having the consistency reduction rate of the mixed solution within the above range increases the degree of freedom in setting the time from preparation of the mixed solution to application, which is preferable from the perspective of production management.

[0106] The method for measuring the consistency of the mixed solution can be exemplified by the method described in Japanese Industrial Standard JIS K 2220:2013, "Grease - Part 7: Consistency Test Method," and in particular, measurement as "immiscible consistency" can be used. Measuring instruments capable of measuring consistency are commercially available, and a specific example is the PENETRO METER manufactured by Nikka Engineering. The measurement procedure involves preparing a container large enough that a conical weight will not come into contact with the container when lowered, filling it with the mixed solution, and placing it in a measuring device with the weight attached. Next, the position of the weight is adjusted to a position where it comes into contact with the mixed solution, and this position is designated as the zero point. Then, at room temperature (25°C), the weight is lowered for 5 seconds (±0.1 seconds), and the depth (mm) of the weight immersed in the mixed solution x 10 is calculated as the consistency. The conical weight may be a standard cone as specified in the Japanese Industrial Standards, with a total mass of 102.5 g ± 0.05 g and a mass of the weight holder of 47.5 ± 0.05 g.

[0107] The coating method and conditions in the coating step are not particularly limited, and any known method can be appropriately adopted. For example, coating can be performed using a comma coater, spin coater, die coater, roll coater, calendar roll, dispenser, etc.

[0108] The molding method and molding conditions in the molding step are not particularly limited, and known methods can be appropriately adopted. For example, compression molding can be performed using a heat press or a vacuum press, followed by drying using a floating oven, an IR oven, or the like. The drying temperature is preferably, for example, 60°C to 150°C. The drying time is preferably, for example, 4 minutes to 20 minutes.

[0109] <Coating layer> The heat insulating material disclosed in this specification preferably includes a coating layer. The coating layer is a layer that serves to prevent inorganic particles and the like from falling off the heat insulating layer and to protect the heat insulating layer. For example, a coating layer formed using a resin film can be preferably used.

[0110] The type of resin for the coating layer is not particularly limited. Specific examples of the resin for the coating layer include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyimide (PI), flame-retardant polycarbonate (PC), breathable porous polyethylene (PE), flame-retardant polyethylene (PE), and biaxially oriented nylon film (Ny). Breathable porous PE preferably has a molecular weight of 1,000,000 to 7,000,000.

[0111] The thickness of the coating layer is not particularly limited and is, for example, 0.001 mm to 0.2 mm, preferably 0.005 mm or more, more preferably 0.007 mm or more, even more preferably 0.010 mm or more, and preferably 0.15 mm or less, more preferably 0.10 mm or less, even more preferably 0.050 mm or less. When the thickness of the coating layer is within the above range, both low thermal conductivity and mechanical strength can be achieved. The thickness of the coating layer can be measured in the same manner as the thickness of the heat insulating layer.

[0112] The number of coating layers is usually 1 or more, preferably 2 or more, and usually 5 or less, preferably 4 or less, and more preferably 3 or less. The two or more coating layers may be two or more resin films, or one resin film may be folded back to form two coating layers. In this case, the number of coating layers is considered to be two.

[0113] When the heat insulating material includes two or more coating layers, the two or more coating layers may sandwich and enclose the heat insulating layer from the thickness direction, and the gap between the coating layers (the space partitioned by the two or more coating layers) may be sealed. The method for sealing the gap between the coating layers is not particularly limited, but examples include a method in which a seal portion is provided on the outer edge of the coating layer and the seal portions between the opposing coating layers are bonded together. The method for bonding the seal portions is also not particularly limited, and examples include welding using heat welding, ultrasonic welding, etc., and adhesion using adhesives, pressure-sensitive adhesives, etc. The welding may be performed by directly welding the resin of the coating layer, or by providing a separate resin layer for welding and welding it.

[0114] The cover layer may be bonded to the adjacent insulating layer with or without an adhesive or pressure-sensitive adhesive, and in some embodiments, it is preferred that the cover layer is not bonded with an adhesive or pressure-sensitive adhesive.

[0115] In the thermal insulation material disclosed herein, the thermal insulation layer may be covered with two or more coating layers in a breathable manner, and may be sealed within a space partitioned by those coating layers. In some embodiments, the coating layer preferably covers the thermal insulation layer in a breathable manner. The method for achieving the breathable coating is not particularly limited. For example, methods such as using a coating layer with through-holes as a ventilation hole or providing a non-sealed portion that functions as a ventilation hole at a portion of the joint between two or more coating layers can be used alone or in appropriate combination. The ventilation hole is typically provided so as to communicate the inside of the coating layer (the thermal insulation layer side) with the external space. A thermal insulation material configured to be breathably covered with a coating layer has good deformability due to the breathability of the coating layer, and is easily compressively deformed, for example, due to volumetric expansion of the cells.

[0116] The number of ventilation holes in the coating layer is usually 1 or more, preferably 2 or more, and usually 50 or less, preferably 25 or less, and more preferably 10 or less.

[0117] The total open area of ​​the vents in the covering layer is typically 0.000079 cm ２ ~10cm ２ It is suitable that the thickness is 0.0001 cm. ２ More preferably, 0.005 cm ２ More preferably, 0.01 cm ２ and preferably 5 cm ２ Less than 4 cm, more preferably ２ Less than 3 cm, more preferably ２ When the total opening area of ​​the vent holes in the coating layer is within the above range, it is easy to prevent powder from leaking out from the heat insulating layer.

[0118] The ventilation holes in the covering layer may be covered with a ventilation membrane. The ventilation membrane usually has an air permeability of 4 cm ３ / (cm 2・s) ~500cm ３ / (cm 2 s), preferably 7 cm ３ / (cm 2 s) or more, more preferably 10 cm ３ / (cm 2 s) or more, more preferably 21 cm ３ / (cm 2 s) or more, and preferably 250 cm ３ / (cm 2 s) or less, more preferably 200 cm ３ / (cm 2 s) or less, more preferably 100 cm ３ / (cm 2 ・s) or less.

[0119] <Buffer layer> The heat insulating material disclosed herein may include a layer other than the heat insulating layer and coating layer described above. One example of such a layer is a buffer layer. The buffer layer may play a role in compensating for physical properties that are insufficient in the heat insulating layer alone. The buffer layer will be described in detail below.

[0120] In some embodiments, a buffer layer made of a fiber-containing fibrous molded body (hereinafter sometimes abbreviated as "fiber molded body") or a buffer layer made of a foam-containing foam-molded body (hereinafter sometimes abbreviated as "foam molded body") may be preferably used.

[0121] (Fiber Molded Product) The type of fiber contained in the fiber molded product is not particularly limited and may be inorganic or organic. Specific examples include inorganic fibers such as glass wool and rock wool, and organic fibers such as cellulose fiber, polyester, and felt made of polypropylene. In some embodiments, inorganic fibers are preferred, and glass wool is particularly preferred. Glass wool is a cured product containing fibers and a thermosetting resin (e.g., a phenolic binder), and the fibers are bonded together with the thermosetting resin. It also has the effect of increasing compressive stress and exhibiting a buffering function. The fiber molded product may contain one type of fiber or two or more types of fibers. The fiber assembly may be in the form of a nonwoven fabric, woven fabric, knitted fabric, or the like, and may be in the form of a nonwoven fabric, for example.

[0122] The fiber content in the fiber molding is not particularly limited, but is, for example, 50% by mass or more (typically 50% by mass to 99% by mass), preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more (for example, 82% by mass or more), and is preferably 97% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less. When the fiber content is within the above range, the fiber molding is likely to exhibit cushioning properties.

[0123] The average fiber length of the fibers in the fiber molding is not particularly limited and is, for example, 1 mm to 200 mm, preferably 5 mm or more, more preferably 10 mm or more, and even more preferably 20 mm or more, and is preferably 175 mm or less, more preferably 150 mm or less, and even more preferably 125 mm or less. When the average fiber length of the fibers is within the above range, the molding is likely to exhibit appropriate cushioning properties.

[0124] The average fiber diameter of the fibers in the fiber molding is not particularly limited and is, for example, 3 μm to 13 μm, preferably 4 μm or more, more preferably 4.5 μm or more, even more preferably 5 μm or more, and is preferably 10 μm or less, more preferably 9 μm or less, even more preferably 8 μm or less. When the average fiber diameter of the fibers is within the above range, the fiber molding is likely to achieve both cushioning properties and low thermal conductivity.

[0125] The fibrous molded product preferably contains a binder in addition to the fibers. The type of binder for the fibrous molded product is not particularly limited, but may be an organic binder or an inorganic binder.

[0126] Specific examples of organic binders include thermoplastic resins, thermoplastic elastomers, thermosetting resins, thermosetting elastomers, sugars, and water-soluble polymers. Specific examples of inorganic binders include aluminum oxide, zirconium oxide, magnesium oxide, titanium oxide, and calcium oxide. When the binder is one of those described above, shape stability is improved. The binders can be used alone or in combination of two or more.

[0127] The binder content in the fiber molding is not particularly limited and is, for example, 1 to 50% by mass of the fiber molding, preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and may be 10% by mass or more or 12% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and may be 18% by mass or less or 16% by mass or less. When the binder content is within the above range, low thermal conductivity and good cushioning properties are achieved.

[0128] In some embodiments, the fiber molded article serving as the buffer layer preferably contains fibers but does not contain hydrophilic fumed silica. The fiber molded article may, for example, contain fibers but not contain inorganic particles. In some embodiments, the fiber molded article serving as the buffer layer preferably contains fibers and a binder but does not contain hydrophilic fumed silica. The fiber molded article may, for example, contain fibers and a binder but not contain inorganic particles. Some fibers used in the fiber molded article are sold with a thermosetting resin dispersed as a binder (adhered to at least a portion of the fibers). These fibers can be cut to the desired shape and then heated and compressed to form a fiber molded article.

[0129] (Foam Molded Article) The foam molded article is a molded article containing a foam. The material of the foam is usually a resin such as a thermoplastic resin or a thermosetting resin. The foam can be molded by appropriately adopting a known molding method and its conditions.

[0130] The type of resin of the foam constituting the foam molded article is not particularly limited. Specific examples include foams formed from resins such as polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate resin, polyvinyl chloride resin (PVC), styrene resins such as polystyrene, polyurethane resins such as polyurethane resin, resol-type phenolic resins such as phenolic resin (PF), melamine resins such as melamine resin (MF), and epoxy resins such as epoxy resin (EP).

[0131] The cell structure of the foamed molded product may be a closed cell structure, an open cell structure, a mixture of these, or an intermediate cell structure. The cell structure of the foamed molded product can be appropriately selected depending on the desired physical properties, etc.

[0132] (Thickness of Buffer Layer) When the thermal insulating material includes a buffer layer, the thickness of the buffer layer is typically 0.5 to 10 mm, but is preferably 1 mm or more, more preferably 1.5 mm or more, even more preferably 2 mm or more, and is preferably 7 mm or less, more preferably 6 mm or less, and even more preferably 5 mm or less. When the thickness of the buffer layer is within the above range, it can appropriately buffer stress generated by battery expansion (e.g., expansion associated with charging a cell). Note that the thickness of the buffer layer can be measured by measuring the cross-sectional thickness of the buffer layer using a thickness gauge (digital thickness gauge JAN-257, probe Φ20, manufactured by Ozaki Manufacturing Co., Ltd.) in the same manner as for the thermal insulating layer, and further, the average value of the values ​​obtained by performing this measurement at any 10 locations can be used.

[0133] (Compression characteristics of buffer layer) The compressive elastic modulus (yield stress / strain) of the buffer layer is, for example, about 0.5 MPa to 20 MPa, preferably 0.7 MPa or more, more preferably 0.9 MPa or more, even more preferably 1.1 MPa or more, and preferably 18 MPa or less, more preferably 16 MPa or less, even more preferably 14 MPa or less.

[0134] The compressive stress when the compressive strain of the buffer layer is 25% is, for example, 0.1 MPa to 4 MPa, preferably 0.2 MPa or more, more preferably 0.3 MPa or more, even more preferably 0.4 MPa or more, and preferably 3.7 MPa or less, more preferably 3.5 MPa or less, even more preferably 3.3 MPa or less.

[0135] The compressive stress when the compressive strain of the buffer layer is 50% is, for example, 0.3 MPa to 7 MPa, preferably 0.5 MPa or more, more preferably 0.6 MPa or more, even more preferably 0.7 MPa or more, and preferably 6.5 MPa or less, more preferably 6.0 MPa or less, even more preferably 5.5 MPa or less.

[0136] The compressive stress when the compressive strain of the buffer layer is 70% is, for example, 2 MPa to 15 MPa, preferably 2.3 MPa or more, more preferably 2.5 MPa or more, even more preferably 2.7 MPa or more, and preferably 14 MPa or less, more preferably 12 MPa or less, even more preferably 10 MPa or less.

[0137] The compressive stress and compressive modulus (yield stress / strain) of the buffer layer can be measured using a precision autograph universal testing machine, etc. Specifically, the buffer layer is cut to a predetermined size to prepare a test specimen (the cross-sectional area parallel to a plane perpendicular to the compression direction is the cross-sectional area used to calculate the compressive stress), and the test specimen is compressed at a predetermined compression rate (e.g., 0.5 mm / min) to measure the compressive stress and displacement, thereby allowing the calculation to be performed.

[0138] (Thermal Properties of Buffer Layer) The thermal conductivity of the buffer layer is not particularly limited. In some embodiments, the thermal conductivity of the buffer layer at 80°C and 2 MPa is, for example, 0.02 W / K·m or more, preferably 0.030 W / K·m or more, more preferably 0.040 W / K·m or more, and even more preferably 0.050 W / K·m or more, and is preferably 0.2 W / K·m or less, more preferably 0.15 W / K·m or less, and even more preferably 0.1 W / K·m or less. The thermal conductivity of the buffer layer at 600°C and 2 MPa is preferably 0.04 W / K·m or more, more preferably 0.05 W / K·m or more, and even more preferably 0.06 W / K·m or more, and is preferably 0.30 W / K·m or less, more preferably 0.25 W / K·m or less, and even more preferably 0.20 W / K·m or less. The thermal conductivity of the buffer layer can be measured using a method similar to that used to measure the thermal conductivity of a thermal insulating material.

[0139] The thermal resistance of the buffer layer is not particularly limited. In some embodiments, the thermal resistance of the buffer layer under conditions of 80°C and 2 MPa is preferably 0.020 (K·m ２ ) / W or more, more preferably 0.025 (K m ２ ) / W or more, more preferably 0.03 (K m ２ ) / W or more, and preferably 0.07 (K m ２ ) / W or less, more preferably 0.06 (K m ２ ) / W or less, more preferably 0.05 (K·m ２ ) / W or less. The thermal resistance of the heat insulating layer under conditions of 600°C and 2 MPa is preferably 0.001 (K·m ２ ) / W or more, more preferably 0.003 (K m ２ ) / W or more, more preferably 0.005 (K·m ２ ) / W or more, and preferably 0.1 (K m ２ ) / W or less, more preferably 0.05 (K·m ２ ) / W or less, more preferably 0.01 (K m ２ ) / W or less. The thermal resistance of the buffer layer can be measured by the same method as that for measuring the thermal resistance of a heat insulating material.

[0140] The thermal resistance of the buffer layer when adjusted to have a thickness of 2 mm without pressure at 80°C and 2 MPa is not particularly limited, but is preferably 0.01 (K·m ２ ) / W or more, more preferably 0.02 (K m ２ ) / W or more, more preferably 0.03 (K m ２ ) / W or more, and preferably 0.10 (K·m ２ ) / W or less, more preferably 0.09 (K m ２ ) / W or less, more preferably 0.08 (K m ２ ) / W or less. The thermal resistance of the buffer layer can be measured by the same method as that for measuring the thermal resistance of the heat insulating layer.

[0141] The number of buffer layers is usually 10 or less, preferably 5 or less, and more preferably 3 or less, and may be 2 or 1.

[0142] The buffer layer may be bonded to an adjacent layer with an adhesive or pressure-sensitive adhesive, or may not be bonded with an adhesive or pressure-sensitive adhesive. In some embodiments, it is preferable that the buffer layer is not bonded with an adhesive or pressure-sensitive adhesive. By not using an adhesive or pressure-sensitive adhesive, an increase in thermal conductivity can be suppressed compared to when an adhesive or pressure-sensitive adhesive is used.

[0143] The shape of the buffer layer is not particularly limited. In some embodiments, the shape of the buffer layer when viewed in plan may be, for example, a polygon such as a quadrangle, a circle, an ellipse, etc. Examples of quadrangles include rectangles (including squares and rectangles).

[0144] <Applications> The applications of the thermal insulating material disclosed herein are not particularly limited, and the thermal insulating material can be used appropriately for known applications that thermal insulating materials are used in. The thermal insulating material according to some embodiments is preferably used as a thermal insulating material disposed between cells of a battery module, and more specifically, is particularly preferably used as a thermal insulating material disposed between cells of a lithium-ion battery module.

[0145] Fig. 1 is a perspective view schematically illustrating an example of a battery module according to an embodiment in which a thermal insulator is disposed between cells, and Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1. As shown in Fig. 1, a battery module 50 includes a plurality of battery cells (here, rectangular cells) 51 arranged in the thickness direction, with a thermal insulator 52 disposed between each of the battery cells 51. The plurality of battery cells 51 thus arranged with the thermal insulator 52 sandwiched between them are typically restrained by applying a pressing force (compressive force) in the thickness direction via restraint plates 52a, 52a disposed at both ends, and are housed in a battery case 53 for use.

[0146] As shown in FIG. 2 , the thermal insulation material 52 has a laminated structure in which a thermal insulation layer 521 and a buffer layer 522 are sandwiched between two resin films (two covering layers) 523A and 523B in the thickness direction. The resin films 523A and 523B are sealed by bonding (e.g., heat welding) at seals provided along their outer edges, and together form the covering material 523. The insulating material 52 having such a structure is sandwiched between two adjacent battery cells 51, thereby providing thermal insulation between the opposing surfaces 51 a of the two battery cells 51. Note that while FIG. 2 shows a structure in which two buffer layers 522A and 522B are stacked within the covering material 523, the number of buffer layers may be one or more, or two or more buffer layers may be arranged separately on both sides of the thermal insulation layer. Similarly, although Fig. 2 shows a configuration having only one insulating layer 521, the number of insulating layers may be two or more. Furthermore, the buffer layer may be disposed on the outside of the cladding material, or multiple buffer layers may be disposed separately on the outside and inside of the cladding material. The cladding material 523 may be provided with ventilation holes.

[0147] Several possible embodiments of the thermal insulation material are described below in more detail. FIG. 3 is a perspective view schematically illustrating a thermal insulation material according to one embodiment, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. As shown in FIG. 4, the thermal insulation material 1 has a configuration in which an insulating layer 10 consisting of two insulating layers 10A and 10B is laminated on one surface 20a of a buffer layer 20, and the insulating layer 10 is sandwiched and enveloped in the thickness direction by two resin films (two coating layers) 31A and 31B. The resin films 31A and 31B are sealed by adhesion (e.g., thermal welding) at seal portions 32 provided along their outer edges, forming a coating material 30. The resin film 31A is formed into a convex shape that generally covers the end face of the laminate of the thermal insulation layer 10 and the buffer layer 20. A vent (through-hole) 33 is formed in the portion covering this end face. A ventilation membrane 34 is disposed at the opening of the vent 33 to the outside to prevent powder from leaking from the thermal insulation layer. When this insulating material 1 is placed between cells in a battery module having a plurality of cells arranged in the thickness direction, for example, it can be used by placing it so that the Z direction (thickness direction of the insulating material 1) shown in Figure 4 is the arrangement direction of the cells and the Y direction is the electrode extraction direction of the cells, i.e., so that the opening direction of the ventilation hole of the insulating material 1 (X direction) and the electrode extraction direction of the cells do not coincide.

[0148] FIG. 5 is a cross-sectional view schematically illustrating another embodiment of a thermal insulation material. In this embodiment, two thermal insulation layers 10A and 10B constituting the thermal insulation layer 10 are laminated separately on one surface 20a and the other surface 20b of the buffer layer 20. A thermal insulation material 1 having such a configuration has high structural symmetry in the thickness direction and is easy to suppress the temperature difference between the two surfaces, which may be advantageous from the perspective of preventing deformation (e.g., warpage) of the thermal insulation material. As shown in the embodiment example in FIG. 6, the buffer layer 20 may have a laminated structure consisting of two layers, namely, buffer layers 20A and 20B, or may have a laminated structure of three or more layers. Furthermore, the inner surface 10a of the thermal insulation layer 10A and the buffer material 20 may or may not be bonded. The same applies to the bonding between the inner surface of the thermal insulation layer 10B and the buffer material 20.

[0149] 7 is a cross-sectional view schematically illustrating a thermal insulation material according to another embodiment. In this embodiment, the thermal insulation layer 10 is enclosed in a covering material 30, while the buffer material 20 is disposed outside the covering material 30. More specifically, one surface 20a of the buffer material 20 is fixed to one surface of the covering material 30 via an adhesive layer 40 made of an adhesive or pressure-sensitive adhesive. The thermal insulation material disclosed herein can also be implemented in such an embodiment.

[0150] The target cells are not limited to rectangular cells, but may be, for example, laminated cells or cylindrical cells. The shape of the heat insulating material can be appropriately adopted depending on the type of cell.

[0151] In addition, target devices for the battery include electric vehicles (EVs), hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs), portable electronic devices such as mobile terminals, mobile phones and notebook computers, and wearable devices.

[0152] As is clear from the above description and the following examples, the present specification discloses the following: [1] A thermal insulation material having a thermal insulation layer containing inorganic particles and inorganic fibers, wherein the electrical conductivity E of the extracted water obtained by heating and extracting 1.0 g of the thermal insulation layer with 50 g of ultrapure water is 0.015 g. Ｓ [2] A thermal insulation material having a thermal insulation layer containing inorganic particles and inorganic fibers, wherein the thermal insulation layer has a moisture absorption amount calculated from a normal mass W0 and a mass W1 after standing in an environment of 85°C and 85% RH for 72 hours by the following formula: Moisture absorption amount [%] = ((W1 - W0) / W0) × 100 of less than 3.5%. [3] A thermal insulation material having a thermal insulation layer containing inorganic particles and inorganic fibers, wherein the thermal insulation layer has a moisture absorption breakdown voltage of 1.25 kV / mm or more, measured after standing in an environment of 85°C and 85% RH for 72 hours to absorb moisture. [4] A thermal insulation material having a thermal insulation layer containing inorganic particles and inorganic fibers, wherein the thermal insulation layer has a moisture absorption breakdown voltage of 1.25 kV / mm or more, measured after standing in an environment of 85°C and 85% RH for 72 hours to absorb moisture. [A] A thermal insulation material having a thermal insulation layer containing inorganic particles and inorganic fibers, wherein the thermal insulation layer satisfies the following conditions: (A) the electrical conductivity E of the extracted water obtained by heating and extracting 1.0 g of the thermal insulation layer with 50 g of ultrapure water Ｓ(B) the heat insulating layer has a moisture absorption amount calculated from a normal mass W0 and a mass W1 after standing in an environment of 85°C and 85% RH for 72 hours by the following formula: Moisture absorption amount [%] = ((W1 - W0) / W0) × 100; of less than 3.5%; and (C) the heat insulating layer has a moisture absorption breakdown voltage of 1.25 kV / mm or more, measured after standing in an environment of 85°C and 85% RH for 72 hours to absorb moisture. [5] The heat insulating material according to any of [1] to [4] above, wherein the heat insulating layer contains the inorganic particles and the inorganic fibers in a mass ratio of 50:50 to 95:5. [6] The heat insulating material according to any one of [1] to [5], wherein the inorganic particles include silicon dioxide particles and the inorganic fibers include glass fibers. [7] The heat insulating layer has a density of 0.2 g / cm ３ ~0.5g / cm ３ [8] The heat insulating material according to any one of [1] to [7] above, wherein the heat insulating layer has a thermal conductivity of 0.045 W / (m·K) or less under conditions of 80°C and a pressurized state of 2 MPa. [9] The heat insulating material according to any one of [1] to [8] above, which is used by being disposed between adjacent cells of a battery module or battery pack including an array of multiple cells.

[10] A heat insulating material disposed between adjacent cells of a battery module or battery pack including an array of multiple cells, the heat insulating material comprising: the heat insulating layer according to any one of [1] to [9] above; and a covering layer that covers the heat insulating layer in a breathable manner.

[0153] Hereinafter, several examples of the present invention will be described, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0154] <Production of Heat Insulating Material (Heat Insulating Layer)> (Example 1) A mixed solvent of 300 parts of isopropyl alcohol (IPA) and 60 parts of manufacturing water was prepared. As the manufacturing water, a solution containing 0.00007 parts of potassium chloride per 100 parts of distilled water was used. Hydrophilic fumed silica ("AEROSIL (registered trademark) 200", manufactured by Nippon Aerosil Co., Ltd., average primary particle size: approximately 12 nm, BET specific surface area: 200 m) was added to 360 parts of the mixed solvent. ２ / g), 100 parts of inorganic glass fiber ("CS 6J-888", manufactured by Nitto Boseki Co., Ltd., average fiber length: 6 mm, average fiber diameter: 11 μm), and "Cortamin 24P" manufactured by Kao Corporation (active ingredient: dodecyltrimethylammonium chloride (C １２ H ２５ N ＋ (CH ３ ) ３ Cl), active ingredient content: 27% by mass), 1.8 parts (0.5 parts as the amount of the active ingredient) were added and mixed to obtain a mixed solution having an initial consistency measured by the method described below in the range of 75 to 110. The obtained mixed solution was applied to a thickness of 2 mm to form a coating film, which was then compression-molded in a hot press to form a sheet with a thickness of 1 mm, and then dried at 100°C for 10 minutes to produce the heat insulating material (heat insulating layer) according to this example.

[0155] The content of dodecyltrimethylammonium chloride contained in the obtained insulation material (insulation layer) was measured by liquid chromatography mass spectrometry (LC / MS). First, standard solutions of several concentrations containing QOTAMINE 24P were prepared, and a calibration curve of dodecyltrimethylammonium chloride concentration and LC / MS area value was created. Next, 0.05 g of insulation material was sampled and added to 25 mL of a 1:1 (volume ratio) mixture of ultrapure water and ethanol, and the mixture was shaken for at least 1 hour to extract the dodecyltrimethylammonium chloride contained in the insulation material. The resulting solution was passed through a membrane filter (0.20 μm) and introduced into the LC / MS, and the content of dodecyltrimethylammonium chloride in the solution was measured using the calibration curve. The content of dodecyltrimethylammonium chloride contained in the insulation material was calculated from the content of dodecyltrimethylammonium chloride contained in 0.05 g of insulation material, and found to be approximately 0.3% by mass. The LC / MS measurement conditions were as follows. Measurement equipment: High-performance liquid chromatograph mass spectrometer (Thermo Fisher Scientific, UltiMate3000 / TSQ QUANTUM ACCESS MAX) Column: "L-column3 C18" manufactured by Chemicals Evaluation and Research Institute, Japan Eluent composition: Pure water (with ammonium acetate) / acetonitrile gradient conditions Flow rate: 0.6 mL / min Detector: MS (full scan: 100-500, m / z=228) Column temperature: 40°C Injection volume: 5 μL Ionization method: ESI (POS) Ion spray voltage: 3.0 kV Evaporation temperature: 350°C Capillary temperature: 270°C

[0156] (Examples 2 to 4, 7 to 12 and Comparative Examples 1 and 2) The heat insulating materials (heat insulating layers) of each example were prepared in the same manner as in Example 1, except that a solution containing the types and amounts of compounds shown in Table 1 per 100 parts of distilled water was used as the manufacturing water.

[0157] In this example, tap water collected at the experimental site was used as is (without adding any ionic compounds afterwards) as the production water. The insulation material (insulation layer) of this example was produced in the same manner as in Example 1, except that this production water was used.

[0158] In this example, the tap water used in Example 5 was softened using a water softener equipped with a cation exchange resin (softened water), and the softened water was used as is (without subsequent addition of an ionic compound) as the production water. A thermal insulating material (thermal insulating layer) according to this example was produced in the same manner as in Example 1, except that this production water was used.

[0159] <Measurement and Evaluation> (Electrical conductivity E of production water Ｍ ) Electrical conductivity E of the water used for production Ｍ was measured in an environment of 23°C and 50% RH using a commercially available electrical conductivity meter (compact electrical conductivity meter "LAQUAwin EC-33B" manufactured by Horiba, Ltd.).

[0160] (Initial Penetration of Mixed Liquid) Penetration was measured as "immiscible penetration" in accordance with the contents of Japanese Industrial Standard JIS K 2220:2013 "Grease - Part 7: Penetration Test Method." Specifically, a container large enough that the conical weight would not come into contact with the container when lowered was prepared, filled with the mixed liquid, and placed in a PENETRO METER manufactured by Nikka Engineering Co., Ltd., to which the weight was attached. Next, the position of the weight was adjusted to a position where the weight and the mixed liquid came into contact, and this position was designated as the zero point. Under room temperature (25°C) conditions, the weight was lowered for 5 seconds (±0.1 seconds), and the depth (mm) of the weight penetrating into the mixed liquid x 10 was calculated as the penetration depth. The conical weight used was a standard cone specified in Japanese Industrial Standards, with a total mass of 102.5 g and a mass of the weight holder of 47.5 g ±0.05 g.

[0161] (Consistency of Mixed Liquid After 24 Hours) Each mixed liquid was allowed to stand for 24 hours, and the consistency thereafter was measured in the same manner as in the "Measurement of Initial Consistency of Mixed Liquid" above.

[0162] (Electrical conductivity of extracted water E Ｓ A sample was cut out from the heat insulating material (heat insulating layer) according to each example, and 1.0 g was weighed. ３50 g of ultrapure water was placed in a container, and the sample was placed in the ultrapure water and immersed in it. The container was sealed with a lid and left to stand in a dryer at 120°C for 2 hours. After 2 hours had passed, the container was removed from the dryer and left to stand in an environment of 23°C and 50% RH for 1 hour to cool, and then the water (extracted water) in the container was withdrawn with a syringe. The extracted water was dropped into a commercially available electrical conductivity meter (compact electrical conductivity meter "LAQUAwin EC-33B" manufactured by Horiba, Ltd.) through a filter (syringe filter manufactured by Merck Millipore, product name "Millex FG" (0.20 μm, hydrophobic PTFE, 25 mm, non-sterile)) attached to the tip of the syringe, and the electrical conductivity E of the extracted water under the above environment was measured. Ｓ was measured.

[0163] (Compressive deformation rate of thermal insulation material (thermal insulation layer)) A compression test was conducted using a precision universal testing machine (Autograph AGS-5kNX, manufactured by Shimadzu Corporation) to compress the thermal insulation material at a compression rate of 0.5 mm / min, and the compressive strain [%] (compressive displacement amount / initial thickness of test piece) and compressive stress [MPa] were measured. The compressive strain when the compressive stress reached 2 MPa was read, and this was adopted as the compressive deformation rate of the thermal insulation material.

[0164] (Thermal Conductivity of Insulating Material (Insulating Layer)) Thermal conductivity was measured at 80°C and 2 MPa in accordance with the contents of Japanese Industrial Standard JIS A 1412-2:1999, "Method for Measuring Thermal Resistance and Thermal Conductivity of Thermal Insulating Materials - Part 2: Heat Flow Meter Method (HFM Method)." First, a sample was prepared by cutting the insulating material (1 mm thick when not pressurized) into a size of 20 mm x 20 mm. A sample, a reference sample (alumina composite material ("RS-100," manufactured by ZIRCAR Refractory Composites, Inc., thickness: 5 mm, thermal conductivity: 0.66 W / (m·K))), and a titanium plate (thickness: 0.2 mm) were prepared. Next, on the lower plate surface of a pneumatic press (manufactured by Imoto Machinery Co., Ltd.), from the top, thermocouple 1 (sheathed thermocouple K type (SCHS1-0), φ = 0.15, class JIS1, manufactured by Chino Corporation), titanium plate, insulating material as a test specimen, titanium plate, thermocouple 2 (sheathed thermocouple K type (SCHS1-0), φ = 0.15, class JIS1, manufactured by Chino Corporation), standard plate, thermocouple 3 (sheathed thermocouple K type (SCHS1-0), φ = 0.15, class JIS1, manufactured by Chino Corporation) were sandwiched in this order to closely contact the insulating material, standard plate, thermocouple, etc. Next, the upper and lower plates were heated and the load of the press was adjusted to 800 N (equivalent to 2 MPa), and then pressurized. In the heated and pressurized state, measurement was continued until the detected temperature of the thermocouple stabilized. The measurement temperatures were two different: one where the upper plate was 80°C and the lower plate was 30°C, and the other where the upper plate was 600°C and the lower plate was 40°C. The temperature was defined as being stable when the temperature change after 10 minutes was within ±0.1°C. The thermal conductivity k1 of the thermal insulation material was calculated from the temperatures detected by each thermocouple after the temperature had stabilized, the thickness of the thermal insulation material when compressed, and the thermal conductivity and thickness of the standard sample using the following formula (I). k1 = k2 × (L1 × ΔT1) / (L2 × ΔT2) (I) (In the formula, k1 is the thermal conductivity of the insulating material [W / (m K)], k2 is the thermal conductivity of the standard plate [W / (m K)], L1 is the thickness of the insulating material when pressed, L2 is the thickness of the standard plate, ΔT1 is the temperature difference between the temperatures of the second thermocouple and the third thermocouple, and ΔT2 is the temperature difference between the temperatures of the first thermocouple and the second thermocouple.)

[0165] (Density of Heat Insulating Material (Heat Insulating Layer)) The heat insulating material according to each example was cut into a size of 20 mm x 20 mm, and the mass and thickness were measured. The mass was divided by the volume to calculate the density [g / cm ３ ] was calculated.

[0166] (Amount of moisture absorption of thermal insulation material (thermal insulation layer)) A sample of approximately 1.0 g was cut out from the thermal insulation material according to each example, and the mass of the sample was precisely weighed in an environment of 23°C and 50% RH, and this was designated as the normal mass W0 [g]. Next, the sample was left to stand in an environment of 85°C and 85% RH for 72 hours to absorb moisture, and then the mass was measured, and this was designated as the mass after moisture absorption W1 [g]. The measurement of the mass after moisture absorption W1 was carried out within 10 minutes after the sample was taken out of the environment of 85°C and 85% RH and placed in an environment of 23°C and 50% RH. Based on the obtained values ​​of W0 and W1, the amount of moisture absorption was calculated using the following formula: Amount of moisture absorption [%] = ((W1 - W0) / W0) x 100

[0167] (Breakdown voltage of thermal insulation material (thermal insulation layer) upon moisture absorption) Four samples used in measuring the mass W1 after moisture absorption were quickly stacked. Using this laminate as the measurement sample, the breakdown voltage was measured in accordance with JIS C2110-1:2016. The measurement was performed using a commercially available breakdown tester (Musashi Intec Co., Ltd., AC withstand voltage tester IPK-:60S (60 kV 5 kVA)) under conditions of 23°C and 50% RH, with a φ25 mm spherical electrode and a voltage rise rate of 500 V / sec.

[0168] The results obtained are shown in Table 1 together with an outline of the heat insulating material according to each example.

[0169]

[0170] As shown in Table 1, in a comparison between Examples 1 to 12 and Comparative Examples 1 and 2, which were produced under the same conditions except for the type and amount of ionic compounds contained in the production water, the insulating materials of Examples 1 to 12 had a higher electrical conductivity E of the extracted water than the insulating materials of Comparative Examples 1 and 2. Ｓ The heat insulating materials of Examples 1 to 6 had a lower electrical conductivity E of extracted water than the heat insulating materials of Examples 7 to 10. ＳThe insulation materials of Examples 1 to 12 also had a clearly higher breakdown voltage when absorbing moisture than the insulation materials of Comparative Examples 1 and 2. The insulation materials of Examples 1 to 6 exhibited an even higher breakdown voltage when absorbing moisture than the insulation materials of Examples 7 to 12.

[0171] Furthermore, the mixed solutions used to prepare the insulating materials in Examples 1 to 12 all maintained a 24-hour consistency of 70 or higher, and no process problems arose with regard to the handleability or moldability of the mixed solutions, either initially (immediately after preparation) or after 24 hours. The mixed solutions of Examples 1 to 9 exhibited more favorable handleability and moldability. Furthermore, the mixed solutions of Examples 1 to 12 all had a consistency loss rate calculated from the initial consistency V0 and the 24-hour consistency V1 using the following formula: Consistency Loss Rate [%] = (V0 - V1) / V0 × 100; which was suppressed to 25% or less, and no significant change in consistency (viscosity increase) was observed over time. The mixed solutions of Examples 1 to 9 all had a consistency loss rate of less than 20%, demonstrating better consistency stability.

[0172] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0173] REFERENCE SIGNS LIST 1 Heat insulating material 10, 10A, 10B, 521 Heat insulating layer 20, 20A, 20B, 522 Buffer layer 30, 523 Covering material (covering layer) 31A, 31B Resin film 32 Sealing portion 33 Ventilation hole 34 Ventilation film 40 Adhesive layer 50 Battery module 51 Battery cell

Claims

1. A heat insulating material having a heat insulating layer containing inorganic particles and inorganic fibers, wherein the electrical conductivity E of the extracted water obtained by heating and extracting 1.0 g of the heat insulating layer with 50 g of ultrapure water is Ｓ A thermal insulating material having a resistivity of 10 μS / cm or more and 60 μS / cm or less.

2. A thermal insulation material having a thermal insulation layer containing inorganic particles and inorganic fibers, wherein the thermal insulation layer has a moisture absorption amount of less than 3.5%, calculated from the normal mass W0 and the mass W1 after being left to stand in an environment of 85°C and 85% RH for 72 hours using the following formula: Moisture absorption amount [%] = ((W1 - W0) / W0) x 100.

3. An insulating material having an insulating layer containing inorganic particles and inorganic fibers, wherein the insulating layer has a moisture-absorbed dielectric breakdown voltage of 1.25 kV / mm or more when measured after being left to stand for 72 hours in an environment of 85°C and 85% RH to absorb moisture.

4. An insulating material according to any one of claims 1 to 3, wherein the insulating layer contains the inorganic particles and the inorganic fibers in a mass ratio of 50:50 to 95:

5.

5. An insulating material according to any one of claims 1 to 3, wherein the inorganic particles include silicon dioxide particles and the inorganic fibers include glass fibers.

6. The heat insulating layer has a density of 0.2 g / cm ３ ~0.5g / cm ３ The heat insulating material according to any one of claims 1 to 3, wherein the thermal conductivity at 80 ° C. and a pressure of 2 MPa is 0.045 W / (m · K) or less.

7. The heat insulating material according to any one of claims 1 to 3, which is used by being disposed between adjacent cells of a battery module or battery pack including a plurality of arranged cells.

8. A heat insulating material disposed between adjacent cells of a battery module or battery pack including a plurality of arranged cells, the heat insulating material comprising the heat insulating layer according to any one of claims 1 to 3 and a covering layer covering the heat insulating layer in a breathable manner.

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