Heat insulating material

Abstract

This thermal insulation material (10) is provided with: thermal insulation layers (11, 12), each of which has a porous structure having a skeleton that is composed of a plurality of particles connected with each other, while having pores inside and hydrophobic portions at least on the surface among the surface and the inside; and a pair of functional layers (16, 17) which are arranged on both sides of the thermal insulation layers (11, 12) in the thickness direction. The pair of functional layers (16, 17) have the same characteristics that include at least one of fire resistance and radiant heat dissipation properties.

Description

Technical Field

[0001] The present disclosure relates to a heat insulating material using a porous structure such as silica aerogel.

Background Art

[0002] Conventionally, various heat insulating materials have been used for in-vehicle parts, residential building materials, industrial equipment, etc. for the purpose of controlling heat flow. In addition to high heat insulation performance, various specifications are required for heat insulating materials according to the application. For example, in a battery pack mounted in a hybrid vehicle or an electric vehicle, a heat insulating material is interposed between adjacent battery cells. As a heat insulating material for a battery pack, for example, Patent Document 1 describes a heat insulating material in which fiber sheets carrying silica aerogel are laminated. Silica aerogel has a structure in which a plurality of silica fine particles are connected to form a skeleton and has a pore structure with a size of about 10 to 50 nm. Therefore, it has a low thermal conductivity and is useful as a constituent material of a heat insulating material. Further, Patent Document 1 describes a configuration in which a heat dissipating material having a high thermal conductivity such as a graphite sheet is disposed between the laminated fiber sheets (paragraphs

[0038] -

[0040] and FIG. 7). According to this configuration, when a battery cell undergoes thermal runaway, the heat in the heat insulating material can be transferred to the housing of the battery pack or the like by the heat dissipating material, so that a rapid temperature rise is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] For the heat insulating material for a battery pack, high heat insulation, fire resistance, electrical insulation, etc. in a high-temperature atmosphere are required. However, the current heat insulating materials do not fully satisfy the required characteristics, and further improvement of characteristics and addition of new characteristics are desired in the heat insulating materials.

[0005] As a heat insulating material with characteristics added other than heat insulation, for example, Patent Document 2 describes a heat insulating material having an aerogel sheet, a sol-impermeable coating layer disposed on one surface of the sheet, and a functional layer disposed on the other surface of the sheet. The sol-impermeable coating layer is a layer that suppresses dust generation by preventing the aerogel from being exposed on the surface of the aerogel sheet (paragraph

[0025] ). The functions of the functional layer include heat diffusion, insulation, sound absorption, vibration resistance, water impermeability, and water vapor permeability, which are characteristics required in electronic components (paragraphs

[0032] -

[0034] ). According to the heat insulating material described in Patent Document 2, the functional layer is disposed only on one side of the aerogel sheet. For this reason, depending on whether the heat source is disposed on one side or the other side of the aerogel sheet, the performance obtained will vary. Also, as the functions of the functional layer, since it is aimed at heat dissipation in electronic components, fire resistance and radiative heat dissipation related to heat transfer at high temperatures are not mentioned.

[0006] In addition, Patent Document 3 describes a heat transfer type heat dissipating material having a heat insulating laminate, an electrical insulating layer disposed on one surface thereof, and a heat transfer layer disposed inside the electrical insulating layer. The heat transfer type heat dissipating material is attached to a device having a heat generating portion and a heat dissipation allowable portion, and dissipates heat from the heat generating portion to the heat dissipation allowable portion by moving the heat through the heat transfer layer inside the electrical insulating layer (paragraph

[0014] , FIG. 2). Patent Document 3 describes a three-layer structure composed of a first base material, a heat insulating layer containing silica aerogel, and a second base material or a functional layer as the heat insulating laminate (paragraph

[0021] ). Here, when the heat insulating laminate is composed of a first base material, a heat insulating layer, and a second base material, it is described that the first base material and the second base material may be of the same type (paragraph

[0040] ). However, the first and second base materials mentioned are merely simple base materials such as cardboard (paragraph

[0024] ) and do not add desired properties such as fire resistance. In the first place, the heat transfer type heat dissipating material described in Patent Document 3 is used by attaching the electrical insulating layer side to the device. That is, since the direction in which the heat source is disposed is determined on one side, there is no need to consider the symmetry of the heat insulating laminate. Therefore, the description regarding the first and second base materials does not suggest the symmetry of the properties of the heat insulating material.

[0007] In view of such circumstances, the present disclosure has been made, and an object thereof is to provide a heat insulating material having at least one of the properties of fire resistance and radiative heat dissipation, and exhibiting the same properties regardless of whether the heat source is disposed on either side in the thickness direction of the heat insulating layer.

Means for Solving the Problems

[0008] (1) To solve the above problems, the heat insulating material of the present disclosure includes a heat insulating layer having a porous structure in which a plurality of particles are connected to form a skeleton, having pores inside, and having a hydrophobic portion at least on the surface among the surface and the inside, and a pair of functional layers disposed on both sides in the thickness direction of the heat insulating layer, and the pair of functional layers have the same properties, and the properties have at least one of fire resistance and radiative heat dissipation. (2) Preferably, in the configuration of (1) above, the pair of the functional layers has a high emissivity material with an emissivity of 0.6 or more, and it is better to have a configuration with radiative heat dissipation property. (3) Preferably, in the configuration of (1) or (2) above, the pair of the functional layers has a high melting point material with a melting point of 500 °C or more, and it is better to have a configuration with fire resistance. (4) Preferably, in any of the configurations of (1) to (3) above, the pair of the functional layers is preferably configured to have electrical insulation property. (5) Preferably, in the configuration of (4) above, the pair of the functional layers has a volume resistivity of 1×10 6 Ω·cm or more and is preferably configured to have an electrical insulating material. (6) Preferably, in any of the configurations of (1) to (5) above, the thermal conductivity of the pair of the functional layers is preferably 2.5 W / m·K or less. (7) Preferably, in any of the configurations of (1) to (6) above, the pair of the functional layers preferably has one or more selected from mica, kaolinite, silica, talc, zirconia, and titanium oxide. (8) Preferably, in any of the configurations of (1) to (7) above, the heat insulating layer has a first heat insulating layer and a second heat insulating layer laminated in the thickness direction, and includes a radiation reflection layer disposed between the first heat insulating layer and the second heat insulating layer, and the pair of the functional layers is preferably disposed on the side opposite to the radiation reflection layer of the first heat insulating layer and on the side opposite to the radiation reflection layer of the second heat insulating layer. (9) Preferably, in the configuration of (8) above, the radiation reflection layer preferably has a low emissivity material with an emissivity of 0.2 or less. (10) Preferably, in the configuration of (8) or (9) above, the radiation reflection layer is preferably a metal foil, a metal vapor deposition film, or a dried film of a metal paste. (11) Preferably, in any of the configurations of (1) to (10) above, the thickness of the heat insulating layer is preferably 100 μm or more and 5000 μm or less. (12) Preferably, in any of the configurations (1) to (11) above, the heat insulation layer preferably has one or more selected from a thickening agent and reinforcing fibers. (13) Preferably, in any of the configurations (1) to (12) above, the heat insulation layer preferably has infrared shielding particles. (14) Preferably, in any of the configurations (1) to (13) above, the porous structure is preferably a silica aerogel in which a plurality of silica fine particles are connected to form a skeleton.

Advantages of the Invention

[0009] In the heat insulating material of the present disclosure, functional layers having the same characteristics are arranged on both sides in the thickness direction of the heat insulating layer. That is, a pair of functional layers are symmetrically arranged with the heat insulating layer interposed therebetween. Therefore, no matter on which side in the thickness direction of the heat insulating layer the heat source is arranged, the characteristics of the functional layer are exhibited in the same manner. The functional layer has either one or both of the characteristics of fire resistance and radiative heat dissipation. When it has fire resistance, for example, when used in a battery pack, it is possible to suppress fire spread in the case where a battery cell undergoes thermal runaway. When it has radiative heat dissipation, the heat insulation property in a high-temperature atmosphere can be improved. In the heat insulating material of the present disclosure, in order to improve the heat insulation property, attention is paid to "radiation", which is the main factor of heat transfer in a high-temperature atmosphere among the three modes of heat transfer (conduction, convection, radiation). "Radiation" is a phenomenon in which heat is transferred by electromagnetic waves, and the higher the temperature, the greater the radiant energy emitted. When the functional layer has radiative heat dissipation, the heat emitted from the heat source is absorbed in the functional layer closer to the heat source, and is re-emitted from the surface on the heat source side, so that the transfer of heat to the heat insulating layer is suppressed, and the heat insulation property of the entire heat insulating material is improved.

[0010] Incidentally, Patent Document 4 describes a silica aerogel blanket containing an opacifying agent that blocks radiant heat. In the silica aerogel blanket, the opacifying agent is mixed with the silica aerogel as part of the heat insulation layer. For this reason, it is impossible to separate the heat transfer suppression function by conduction by the silica aerogel and convection, and the radiant heat blocking function by the opacifying agent, and it is difficult to take optimal heat countermeasures. Further, the second aerogel layer containing the opacifying agent is disposed between the first aerogel layer and the third aerogel layer so that the opacifying agent is not exposed on the surface of the aerogel blanket. Since the second aerogel layer contains silica aerogel and is a single layer as a heat insulation layer, it is disposed on the heat source side separately from the heat insulation layer and does not function to suppress heat transfer to the heat insulation layer.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the heat insulating material of the present disclosure will be described.

[0013] <First Embodiment> [Configuration] First, the configuration of the heat insulating material of the present embodiment will be described. FIG. 1 shows a cross-sectional view of the heat insulating material of the present embodiment in the thickness direction. In FIG. 1, for convenience, the stacking direction (thickness direction) of the members is defined as the left-right direction. As shown in FIG. 1, the heat insulating material 10 includes a first heat insulating layer 11, a second heat insulating layer 12, a first base material 13, a second base material 14, a radiation reflecting layer 15, a first functional layer 16, and a second functional layer 17. The first heat insulating layer 11, the first base material 13, and the first functional layer 16, and the second heat insulating layer 12, the second base material 14, and the second functional layer 17 are arranged symmetrically with respect to the radiation reflecting layer 15 interposed therebetween. The first functional layer 16 and the second functional layer 17 are arranged symmetrically with respect to the first heat insulating layer 11 and the second heat insulating layer 12 interposed therebetween. Here, the first heat insulating layer 11 and the second heat insulating layer 12 are the same in configuration, shape, and dimensions. The first base material 13 and the second base material 14 are the same in configuration, shape, and dimensions. The first functional layer 16 and the second functional layer 17 are the same in configuration, shape, and dimensions. Therefore, regarding the heat insulating layer, the base material, and the functional layer, the first heat insulating layer 11, the first base material 13, and the first functional layer 16 will be described as representatives of each.

[0014] The first heat insulating layer 11 has a rectangular sheet shape with a thickness of 1000 μm. The first heat insulating layer 11 includes silica aerogel, silica particles and gypsum as a binder, carboxymethyl cellulose sodium (CMC) and polyethylene oxide (PEO) as a thickener, and glass fiber as a reinforcing fiber. The silica particles are nanoparticles with an average particle diameter of 12 nm. The content of silica aerogel in the first heat insulating layer 11 is 64% by mass when the whole of the first heat insulating layer 11 is 100% by mass.

[0015] The first base material 13 is disposed on the left side of the first heat insulation layer 11. The first base material 13 is made of glass cloth. The first base material 13 has a rectangular sheet shape with a thickness of 100 μm, and the size in the plane direction is slightly larger than that of the first heat insulation layer 11. At the contact surface between the first heat insulation layer 11 and the first base material 13, a part of the first heat insulation layer 11 is impregnated into the spaces (hole parts) between the fibers of the first base material 13. Around the first heat insulation layer 11 and the second heat insulation layer 12, the first base material 13 and the second base material 14 overlap and are fused together. The first heat insulation layer 11, the second heat insulation layer 12, and the radiation reflection layer 15 are accommodated in a bag-shaped closed space formed by the first base material 13 and the second base material 14.

[0016] The radiation reflection layer 15 is interposed between the first heat insulation layer 11 and the second heat insulation layer 12. The radiation reflection layer 15 is made of aluminum foil. The thickness of the radiation reflection layer 15 is 100 μm, and the emissivity is 0.04.

[0017] The first functional layer 16 is disposed on the outer surface (left surface) of the first base material 13. The first functional layer 16 is disposed on the side opposite to the radiation reflection layer 15 of the first heat insulation layer 11. The first functional layer 16 has a thin film shape with a thickness of 200 μm. The first functional layer 16 includes mica, kaolinite, ammonium polyphosphate as a flame retardant, and urethane resin as a binder. The emissivity of mica is 0.7, the melting point is 1250 °C, the volume resistivity is 1×10 14 Ω·cm, and the thermal conductivity (perpendicular to the plane) is 0.67 W / m·K. The emissivity of kaolinite is 0.9, the melting point is 1100 °C, the volume resistivity is 1×10 12 Ω·cm, and the thermal conductivity is 0.3 W / m·K. The emissivity of the first functional layer 16 is 0.6, the electrical resistivity in the thickness direction is 1×10 6 Ω·cm, and the thermal conductivity is 2.5 W / m·K. The first functional layer 16 satisfies the V-0 standard in the UL94 standard combustion test. Thus, the first functional layer 16 has fire resistance, radiation heat dissipation, and electrical insulation properties, and the thermal conductivity of the first functional layer 16 is relatively low.

[0018] [Manufacturing method] Next, a method for manufacturing the heat insulating material of the present embodiment will be described. First, water is added to colloidal silica, CMC and PEO are added thereto and stirred, then silica aerogel and glass fiber are added and stirred, and further gypsum is added and stirred to prepare a composition for the heat insulating layer. Similarly, water is added to the urethane resin emulsion, mica, kaolinite, and ammonium polyphosphate are added thereto and stirred to prepare a composition for the functional layer. Next, the prepared composition for the heat insulating layer is applied to one surface of the first base material 13 and one surface of the second base material 14, respectively, to form a coating film with a thickness of 1000 μm. Then, an aluminum foil (radiation reflecting layer 15) is disposed on the surface of the coating film of the first base material 13, and the first base material 13 and the second base material 14 are overlapped so that the two coating films are laminated via the aluminum foil. Then, the obtained laminate is disposed in a molding die and pressed while heating to 150°C. As a result, the coating film is cured to form the first heat insulating layer 11 and the second heat insulating layer 12. Further, the overlapping portion of the first base material 13 and the second base material 14 is fused. Finally, the prepared composition for the functional layer is applied to the other surface (outer surface) of the first base material 13 and the other surface (outer surface) of the second base material 14, respectively, and dried at a temperature of about 100°C to form the first functional layer 16 and the second functional layer 17.

[0019] [Function and Effect] Next, the function and effect of the heat insulating material of the present embodiment will be described. The heat insulating layer in the heat insulating material 10 of the present embodiment has a first heat insulating layer 11 and a second heat insulating layer 12 laminated in the thickness direction. On both sides in the thickness direction (left-right direction) of the heat insulating layer (the first heat insulating layer 11 and the second heat insulating layer 12), a pair of functional layers (the first functional layer 16 and the second functional layer 17) having the same configuration are disposed. Since the pair of functional layers 16 and 17 are symmetrically disposed with the heat insulating layers 11 and 12 interposed therebetween, the characteristics of the functional layers 16 and 17 are exhibited in the same manner regardless of whether the heat source is disposed on either side in the left-right direction of the heat insulating material 10. Further, since the heat insulating layers 11 and 12 are covered by the functional layers 16 and 17, the first base material 13, and the second base material 14, it is effective in suppressing the dropout of the silica aerogel.

[0020] The functional layers 16 and 17 contain mica and kaolinite. Both of these are high-emissivity materials with an emissivity of 0.6 or more, high-melting-point materials with a melting point of 500°C or more, and electrical insulating materials with a volume resistivity of 1×10 6 Ω·cm or more. Furthermore, the functional layers 16 and 17 also contain ammonium polyphosphate as a flame retardant. Therefore, the functional layers 16 and 17 have fire resistance, radiant heat dissipation properties, and electrical insulation properties. Since the functional layers 16 and 17 have fire resistance, for example, when the heat insulating material 10 is disposed between battery cells of a battery pack, it is possible to suppress the spread of fire due to thermal runaway of the battery cells. Since the functional layers 16 and 17 have radiant heat dissipation properties, the heat released from the heat source is absorbed in the functional layers 16 and 17 and re-emitted from the surface on the heat source side. As a result, the transfer of heat to the heat insulating layers 11 and 12 is suppressed, and the heat insulation property of the entire heat insulating material 10 is enhanced. "Radiation" is a major factor in heat transfer in a high-temperature atmosphere. Therefore, by suppressing this, the heat insulation property, particularly in a high-temperature atmosphere, is improved. Furthermore, since the functional layers 16 and 17 have electrical insulation properties, they are also suitable for applications that require electrical insulation in addition to heat insulation, such as electronic devices and battery packs. Also, since the functional layers 16 and 17 having electrical insulation properties are disposed on the outermost layer of the heat insulating material 10, even if it has a conductive material (radiation reflecting layer 15 made of aluminum foil) inside, conduction to the outside can be blocked. Also, the thermal conductivity of the functional layers 16 and 17 is relatively low. Therefore, heat conduction in the overlapping portion of the first base material 13 and the second base material 14 that does not pass through the heat insulating layers 11 and 12 can also be suppressed.

[0021] The heat insulating material 10 has a radiation reflecting layer 15 between the first heat insulating layer 11 and the second heat insulating layer 12. The radiation reflecting layer 15 is made of aluminum foil. Aluminum foil is a low-emissivity material with an emissivity of 0.2 or less. Therefore, the heat that reaches from the heat source through the first functional layer 16, the first base material 13, and the first heat insulating layer 11, or through the second functional layer 17, the second base material 14, and the second heat insulating layer 12, is reflected by the radiation reflecting layer 15. As a result, most of the heat released from the heat source can be blocked by the heat insulating material 10. According to the heat insulating material 10, the heat resistance increases due to the lamination of the first heat insulating layer 11, the radiation reflecting layer 15, and the second heat insulating layer 12. Thereby, the heat insulation property of the entire heat insulating material 10 can be enhanced.

[0022] In the heat insulation layers 11 and 12, the binders that bind the constituent components such as silica aerogel are silica particles and gypsum. Thereby, even when used in a high-temperature atmosphere, decomposition and deterioration of the binder are less likely to occur, generation of cracks in the heat insulation layers 11 and 12 is suppressed, and thus the heat insulation structure can be maintained. Further, since the heat insulation layers 11 and 12 become relatively hard, the heat insulation layers 11 and 12 are not easily crushed even when compressed, and the heat insulation structure can be maintained. The heat insulation layers 11 and 12 have glass fibers (reinforcing fibers). Due to the actions of both the inorganic binder such as silica particles and the glass fibers, the shape retention in a high-temperature atmosphere is improved and it becomes difficult to be crushed even when compressed. Further, by having glass fibers, the stability and film-forming property of the composition for the heat insulation layer are improved, and the dropout of the silica aerogel is suppressed. The heat insulation layers 11 and 12 have CMC and PEO (thickeners). Thereby, the viscosity of the composition for the heat insulation layer becomes high, the water suspension property of the hydrophobic silica aerogel is improved, and the silica aerogel is easily dispersed. Further, since flexibility is imparted, generation of cracks during the production of the heat insulation layers 11 and 12 can be suppressed.

[0023] <Second Embodiment> The difference between the heat insulating material of the present embodiment and the heat insulating material of the first embodiment is that it does not include the first base material and the second base material. Here, the description will focus on the differences. Fig. 2 shows a cross-sectional view in the thickness direction of the heat insulating material of the present embodiment. In Fig. 2, members corresponding to those in Fig. 1 are denoted by the same reference numerals.

[0024] As shown in Fig. 2, the heat insulating material 20 includes a first heat insulating layer 11, a second heat insulating layer 12, a radiation reflecting layer 15, a first functional layer 16, and a second functional layer 17. The first heat insulating layer 11 and the first functional layer 16, and the second heat insulating layer 12 and the second functional layer 17 are arranged symmetrically with respect to the radiation reflecting layer 15 interposed therebetween. The first functional layer 16 and the second functional layer 17 are arranged symmetrically with respect to the first heat insulating layer 11 and the second heat insulating layer 12 interposed therebetween. The first functional layer 16 is disposed on the surface (left surface) of the first heat insulating layer 11 opposite to the radiation reflecting layer 15. The second functional layer 17 is disposed on the surface (right surface) of the second heat insulating layer 12 opposite to the radiation reflecting layer 15. Since the configuration of each layer is the same as that of the first embodiment, the description thereof is omitted.

[0025] The manufacturing method of the heat insulating material 20 is as follows. First, in the same manner as in the first embodiment, a composition for a heat insulating layer and a composition for a functional layer are prepared. Next, the prepared composition for a heat insulating layer is preformed into a sheet shape with a thickness of 1000 μm. Subsequently, the preformed sheet-shaped composition for a heat insulating layer is disposed on both surfaces of an aluminum foil (radiation reflecting layer 15) and pressure-bonded, and then dried at 150°C. Thereby, the first heat insulating layer 11 and the second heat insulating layer 12 are formed on both surfaces of the radiation reflecting layer 15. Then, the prepared composition for a functional layer is applied to the surfaces of the first heat insulating layer 11 and the second heat insulating layer 12, respectively, and dried at a temperature of about 100°C to form the first functional layer 16 and the second functional layer 17.

[0026] The heat insulating material 20 of the present embodiment has the same effects as the heat insulating material 10 of the first embodiment with respect to the common parts of the configuration. According to the heat insulating material 20, since a base material is not required, it is easy to reduce the thickness, and the cost is reduced by the number of components being small.

[0027] <Third Embodiment> The difference between the heat insulating material of the present embodiment and the heat insulating material of the second embodiment is that a functional layer is disposed not only on the surfaces of the first heat insulating layer and the second heat insulating layer but also on the end faces including the radiation reflecting layer. Here, the description will be centered on the differences. Fig. 3 shows a cross-sectional view in the thickness direction of the heat insulating material of the present embodiment. In Fig. 3, members corresponding to those in Fig. 2 are denoted by the same reference numerals.

[0028] As shown in FIG. 3, the heat insulating material 30 includes a first heat insulating layer 11, a second heat insulating layer 12, a radiation reflecting layer 15, a first functional layer 16, a second functional layer 17, and a third functional layer 18. The first functional layer 16 and the second functional layer 17 are arranged symmetrically with respect to the left and right, sandwiching the first heat insulating layer 11 and the second heat insulating layer 12. The first functional layer 16 is arranged on the surface (left surface) of the first heat insulating layer 11 opposite to the radiation reflecting layer 15. The second functional layer 17 is arranged on the surface (right surface) of the second heat insulating layer 12 opposite to the radiation reflecting layer 15. The third functional layer 18 is arranged on the four end faces in the thickness direction of the first heat insulating layer 11, the second heat insulating layer 12, and the radiation reflecting layer 15. The third functional layer 18 is formed continuously with the first functional layer 16 and the second functional layer 17 and has the same configuration and characteristics as both layers. That is, the first functional layer 18 has mica, kaolinite, ammonium polyphosphate, and urethane resin, and has fire resistance, radiation heat dissipation, and electrical insulation. Since the configurations of the layers other than the third functional layer 18 are the same as those in the first embodiment, the description thereof is omitted. The first functional layer 16 and the second functional layer 17 are arranged on the left and right surfaces of the heat insulating material 30, and the third functional layer 18 is arranged on the four end faces. That is, the entire outer side of the heat insulating material 30 is covered with the functional layers 16, 17, 18 having fire resistance, radiation heat dissipation, and electrical insulation.

[0029] The manufacturing method of the heat insulating material 30 is as follows. First, in the same manner as in the first embodiment, a composition for the heat insulating layer and a composition for the functional layer are prepared. Next, in the same manner as in the second embodiment, the first heat insulating layer 11 and the second heat insulating layer 12 are formed on both surfaces of the radiation reflecting layer 15. Then, the prepared composition for the functional layer is applied to the surfaces of the first heat insulating layer 11 and the second heat insulating layer 12 and the four end faces in the thickness direction including the radiation reflecting layer 15, and dried at a temperature of about 100° C. to form the first functional layer 16, the second functional layer 17, and the third functional layer 18.

[0030] The heat insulation material 30 of this embodiment has the same functions and effects as the heat insulation material 10 of the first embodiment and the heat insulation material 20 of the second embodiment for the parts with the same configuration. According to the heat insulation material 30, since the entire outer side is covered with the functional layers 16, 17, and 18 having fire resistance and the like, the heat and flame blocking effect is higher and the safety is further improved.

[0031] <Fourth Embodiment> The difference between the heat insulation material of this embodiment and the heat insulation material of the first embodiment is that the heat insulation layer is a single layer and does not have a radiation reflection layer. Here, the description will focus on the differences. FIG. 4 shows a cross-sectional view of the heat insulation material of this embodiment in the thickness direction. In FIG. 4, the members corresponding to those in FIG. 1 are denoted by the same reference numerals.

[0032] As shown in FIG. 4, the heat insulation material 40 includes a heat insulation layer 41, a first base material 13, a second base material 14, a first functional layer 16, and a second functional layer 17. The first functional layer 16 and the second functional layer 17 are arranged symmetrically with respect to the left and right across the heat insulation layer 41. The heat insulation layer 41 has a rectangular sheet shape with a thickness of 2000 μm. The configuration of the heat insulation layer 41 is the same as that of the first heat insulation layer 11 and the second heat insulation layer 12 of the first embodiment, and it has silica aerogel, silica particles, CMC, PEO, and glass fibers.

[0033] The manufacturing method of the heat insulation material 40 is as follows. First, in the same manner as in the first embodiment, a composition for the heat insulation layer and a composition for the functional layer are prepared. Next, the prepared composition for the functional layer is applied to one surface of the first base material 13 to form a coating film with a thickness of 2000 μm. Subsequently, the second base material 14 is overlapped so as to cover the formed coating film. This is placed in a mold and pressed while heating to 150°C. Thereby, the coating film is cured to become the heat insulation layer 41. Also, at the periphery of the heat insulation layer 41, the overlapping portion of the first base material 13 and the second base material 14 is fused. Then, the prepared composition for the functional layer is applied to the other surface (outer surface) of the first base material 13 and the other surface (outer surface) of the second base material 14, respectively, and dried at a temperature of about 100°C to form the first functional layer 16 and the second functional layer 17.

[0034] The heat insulating material 40 of this embodiment has the same functions and effects as the heat insulating material 10 of the first embodiment for the parts with the same configuration. According to the heat insulating material 40, since the radiation reflection layer is not arranged, the heat insulating layer 41 can be made into a single layer, which facilitates manufacturing and reduces costs.

[0035] <Other forms> As described above, four embodiments of the heat insulating material of the present disclosure have been explained. However, the embodiments are not limited to the above forms. It is also possible to implement in various modified forms and improved forms that those skilled in the art can perform.

[0036] [Configuration of heat insulating material] The heat insulating material of the present disclosure may include a heat insulating layer and a pair of functional layers arranged on both sides in the thickness direction of the heat insulating layer, and the other configurations are not particularly limited.

[0037] (1) Heat insulating layer The heat insulating layer may be a single layer or two or more layers. In the case of two or more layers, other layers may be interposed between the heat insulating layers. The total thickness of the heat insulating layer may be appropriately determined according to the application. From the viewpoint of heat insulation performance, the thickness of each layer of the heat insulating layer is desirably 100 μm or more, 300 μm or more, or 500 μm or more. If the heat insulating layer is too thick, not only the cost will increase, but also the strength will decrease and it will become brittle. Therefore, the thickness of each layer of the heat insulating layer is desirably 5000 μm or less, 3000 μm or less, or 2000 μm or less. The heat insulating layer has a porous structure.

[0038] The porous structure is formed by a plurality of particles connected to form a skeleton and having pores inside. The diameter of the particles (primary particles) forming the skeleton is preferably about 2 to 5 nm, and the size of the pores formed between the skeletons is preferably about 10 to 50 nm. Most of the pores are so-called mesopores with a size of 50 nm or less. Since the mesopores are smaller than the mean free path of air, the convection of air is restricted and the heat transfer is inhibited. The shape of the porous structure is not particularly limited, such as spherical or irregularly shaped lumps, but a chamfered shape or a spherical shape is preferred. In this case, since the dispersibility in the liquid is improved, it becomes easy to prepare a composition for producing a heat insulating layer (composition for heat insulating layer). Also, the voids between the porous structures can be reduced and the filling amount can be increased, thereby enhancing the heat insulation property. The porous structure may be used in the as-manufactured state, or it may be further pulverized and used. For the pulverization treatment, a pulverization device such as a jet mill or a spheroidization treatment device may be used. By performing the pulverization treatment, the corners of the particles are removed and the particles become rounded. As a result, the particles are more likely to bond to each other and the porous structure is less likely to fall off. Also, the surface of the heat insulating layer becomes smooth and cracks are less likely to occur.

[0039] When the maximum length of the porous structure is taken as the particle diameter, the average particle diameter of the porous structure is preferably about 1 to 200 μm. The larger the particle diameter of the porous structure, the smaller the surface area and the larger the pore volume, so the effect of enhancing the heat insulation property becomes greater. For example, those with an average particle diameter of 10 μm or more are suitable. On the other hand, considering the stability of the composition for heat insulating layer and the ease of coating, those with an average particle diameter of 100 μm or less are suitable. Also, when using two or more types with different particle diameters in combination, the porous structure with a smaller diameter enters the gaps between the porous structures with a larger diameter, so the filling amount can be increased and the effect of enhancing the heat insulation property becomes greater.

[0040] The porous structure has a hydrophobic site at least on the surface among the surface and the interior. When having a hydrophobic site on the surface, penetration of moisture and the like can be suppressed, so that the pore structure is maintained and the heat insulation property is hardly impaired. For example, by performing surface treatment with a silane coupling agent or the like, functions such as hydrophobicity can be imparted to the surface of the porous structure. Further, in the manufacturing process of the porous structure, a hydrophobization treatment such as imparting a hydrophobic group may be performed.

[0041] The type of the porous structure is not particularly limited. Examples of the primary particles include silica, alumina, zirconia, titania, and the like. Among them, from the viewpoint of excellent chemical stability, it is desirable that the primary particle is silica, that is, a silica aerogel in which a plurality of silica fine particles are connected to form a skeleton. The silica aerogel exhibits white and reflects infrared rays. Therefore, when using the silica aerogel, a heat shielding effect can be imparted to the heat insulation layer.

[0042] The manufacturing method of the silica aerogel is not particularly limited, and it may be one in which the drying process is performed at normal pressure or one in which it is performed supercritically. For example, if the hydrophobization treatment is performed before the drying process, it is not necessary to dry supercritically, that is, it may be dried at normal pressure, so that it can be manufactured more easily and at a lower cost. Depending on the difference in the drying method when manufacturing the aerogel, one dried at normal pressure may be called "xerogel" and one dried supercritically may be called "aerogel", but in this specification, both are collectively referred to as "aerogel".

[0043] The content of the porous structure in the heat insulation layer may be appropriately determined in consideration of heat insulation performance, mechanical strength, etc. For example, from the perspective of reducing the thermal conductivity (increasing the heat insulation performance), the content of the porous structure is desirably 40% by mass or more when the total mass of the heat insulation layer is 100% by mass. It is more preferable that it is 50% by mass or more, or 60% by mass or more. On the other hand, as the amount of the porous structure increases, there is a risk that the porous structure is likely to fall off. Therefore, the content of the porous structure is desirably 75% by mass or less when the total mass of the heat insulation layer is 100% by mass. It is more preferable that it is 70% by mass or less.

[0044] From the perspective of ensuring self-supportability of the heat insulation layer, that is, the heat insulation layer can support its own weight alone and can be handled alone, the heat insulation layer may contain a binder that binds components such as the porous structure. However, if a binder exists on the surface or in the gaps of components such as the porous structure, there is a risk that a heat transfer path is formed through the binder. Therefore, from the perspective of suppressing the formation of the heat transfer path and realizing high heat insulation performance in a high-temperature atmosphere, it is desirable that the heat insulation layer has no binder.

[0045] When the heat insulating layer has a binder, from the viewpoint of facilitating the preparation of the heat insulating layer composition, it is preferable to use a binder (aqueous binder) having water (including pure water, tap water, etc.) as a solvent. The component of the binder may be an organic material or an inorganic material. From the viewpoint of reducing the decomposition and deterioration of the organic component when used in a high-temperature atmosphere and suppressing the occurrence of cracks and the like, it is desirable to use an inorganic binder in which the component of the binder is an inorganic material. Examples of the inorganic material include metal oxides such as silica, titania, zinc oxide, and zirconia, as well as water glass (sodium silicate), cement, plaster, magnesium silicate, quicklime, and slaked lime. Among them, a binder having silica is preferable because it is easily compatible with the porous structure and is inexpensive and easily available. In addition, a high-strength heat insulating layer can be formed by binding while reacting with water as a solvent and filling the gaps between the porous structures. Cement, plaster, and magnesium silicate, which are hydraulic materials, are also preferable because they are inexpensive and easily available.

[0046] When the inorganic material is nanoparticles (particles on the order of nanometers), the disadvantages of hardness and brittleness due to the heat insulating layer having the inorganic material can be improved. As the binder having silica nanoparticles, colloidal silica having water as a dispersion medium, sodium silicate solution, etc. may be used. As the binder having titania nanoparticles, an aqueous dispersion of titania, etc. may be used.

[0047] Examples of the organic binder in which the component of the binder is an organic material include a water-soluble binder and an emulsion-like binder. Among them, an emulsion-like binder (aqueous emulsion-based binder) is preferable. The aqueous emulsion-based binder is emulsified by introducing a surfactant or a hydrophilic group. According to the aqueous emulsion-based binder, since the surfactant and the hydrophilic group volatilize during drying, the hydrophilicity decreases and it becomes difficult to dissolve in water. Therefore, it is considered that stickiness is less likely to occur after the heat insulating layer composition is cured. As the emulsification method, either a forced emulsification type using a surfactant as an emulsifier or a self-emulsification type having a hydrophilic group introduced may be used.

[0048] The organic material may be either a resin or a rubber. From the viewpoints of having high adhesiveness to the porous structure and making the heat insulation layer flexible and less likely to crack, the glass transition temperature (Tg) of the binder is desirably -5°C or lower, and more desirably -20°C or lower. For example, in the case of an aqueous emulsion-based binder, it may be a resin emulsion or a rubber emulsion. Examples of the resin include acrylic resin, urethane resin, and a mixture of acrylic resin and urethane resin. Examples of the rubber include styrene-butadiene rubber (SBR), nitrile rubber, silicone rubber, urethane rubber, and acrylic rubber. From the viewpoint of making the heat insulation layer flexible, urethane resin, SBR, etc. are suitable. From the viewpoint of increasing the strength of the binder portion and improving the strength of the heat insulation layer, a crosslinking agent or the like may be used in combination to crosslink the binder components.

[0049] In addition to the porous structure and the binder, the heat insulation layer may contain other components such as infrared shielding particles, crosslinking agents, thickening agents, reinforcing fibers, and flame retardants. A porous structure having a hydrophobic site on its surface or inside is not easily wetted by water. Among them, silica aerogel has a small specific gravity and thus easily floats on water. Therefore, it is difficult to disperse silica aerogel in a liquid (including slurry)-type heat insulation layer composition using water as a solvent, and the dispersion process takes time. For example, when a thickening agent is blended, the viscosity of the heat insulation layer composition increases, the water suspension property of the hydrophobic porous structure is improved, and the porous structure is easily dispersed. Thereby, the time required for dispersing the porous structure can be shortened, and the productivity can be increased. In addition, since flexibility is imparted to the heat insulation layer, the generation of cracks is also suppressed. As the thickening agent, in addition to CMC and PEO used in the above embodiment, polysaccharides such as carboxyethyl cellulose, carboxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, xanthan gum, agarose, and carrageenan, polyvinyl alcohol, glucomannan, etc. may be used.

[0050] The infrared shielding particles absorb heat from the heat source and re-emit it from the surface on the heat source side, thereby blocking the radiant heat from the heat source. Therefore, when the infrared shielding particles are blended, the heat insulation property, particularly in a high-temperature atmosphere, is improved. Examples of the infrared shielding particles include silicon carbide, kaolinite, montmorillonite, silicon nitride, mica, alumina, zirconia, aluminum nitride, titanium oxide, zirconium silicate, zinc oxide, tantalum oxide, tungsten oxide, niobium oxide, indium tin oxide, cerium oxide, boron carbide, manganese oxide, tin oxide, bismuth oxide, iron oxide, magnesium oxide, barium titanate, and the like.

[0051] When the reinforcing fiber is blended, it physically entangles around the porous structure, thereby improving the mechanical strength of the heat insulation layer and suppressing the detachment of the porous structure. The type of the reinforcing fiber is not particularly limited, but considering heat resistance and the like, ceramic fibers such as glass fiber and alumina fiber are suitable.

[0052] When the flame retardant is blended, the heat insulation layer can be imparted with flame retardancy. As the flame retardant, known ones such as halogen-based, phosphorus-based, and metal hydroxide-based ones may be used. Considering the environmental load, it is desirable to use a phosphorus-based flame retardant. Examples of the phosphorus-based flame retardant include ammonium polyphosphate, red phosphorus, and phosphate ester. Among them, those insoluble in water are desirable because the flame retardant hardly flows out even when it comes into contact with moisture during use. For example, ammonium polyphosphate is suitable.

[0053] (2) Functional layer On both sides in the thickness direction of the heat insulating layer, a pair of functional layers having the same characteristics are arranged. For example, when the heat insulating layer is composed of two or more layers of laminates, the pair of functional layers may be arranged on both sides of the outermost heat insulating layer. The functional layer may be one layer or two or more layers, but it is preferably one layer from the viewpoints of thinning and cost. It is desirable that the functional layer has a form having a plurality of characteristics (multi-functional) in one layer. As long as the pair of functional layers have the same characteristics as a whole layer, the layer configuration, components, shape, dimensions, etc. may be different, such as one layer or two layers. Considering the ease of imparting characteristics and the ease of manufacturing, etc., it is desirable that the pair of functional layers have at least the same layer configuration and components. In this specification, a form in which two functional layers that exhibit the same function are arranged on both sides of the heat insulating layer is referred to as being arranged "symmetrically".

[0054] The pair of functional layers have at least one of fire resistance and radiant heat dissipation. For example, when used in a battery pack, a heated cigarette, a heat insulating sheet for fire prevention, etc., it is desirable that the functional layer has fire resistance. In this specification, "the functional layer has fire resistance" means satisfying at least one of the following two conditions (i) and (ii). (i) The sample of the functional layer conforms to any one of the standards of V-0, V-1, or V-2 in the combustion test of the UL94 standard. (ii) When a flame of 1000 °C and a length of 10 ± 2 cm is ejected by a propane gas burner and the heat insulating material is held for 1 minute at a position 5 ± 1 cm away from the flame, there is no perforation.

[0055] From the viewpoint of fire resistance, it is desirable that the functional layer has a high melting point material with a melting point of 500 °C or higher. Examples of the high melting point material include talc, kaolinite, montmorillonite, mica, silica, potassium titanate, titanium oxide, silicon nitride, alumina, aluminum nitride, silicon carbide, zirconia, etc. Also, similar to the heat insulating layer, it may have a flame retardant such as a halogen-based, phosphorus-based, or metal hydroxide-based one.

[0056] For example, when used in a battery pack, a heated cigarette, a heat-insulating sheet for fire prevention, etc., it is desirable to improve the heat-insulating property in a high-temperature atmosphere. In such a case, it is desirable that the functional layer has radiative heat dissipation property. In this specification, "the functional layer has radiative heat dissipation property" means that the surface emissivity of the functional layer is 0.6 or more. The emissivity may be measured using a known measuring device (for example, "Emissivity Meter TSS-5X" manufactured by Japan Sensor Co., Ltd.).

[0057] From the viewpoint of radiative heat dissipation property, it is desirable that the functional layer has a high-emissivity material with an emissivity of 0.6 or more. Examples of the high-emissivity material include mica, zirconia, alumina, aluminum nitride, silicon nitride, kaolinite, montmorillonite, and silicon carbide.

[0058] Suitable properties of the functional layer include fire resistance, radiative heat dissipation property, and in addition, electrical insulation property. For example, when used in an electronic device, a battery pack, etc., it is desirable that the functional layer has electrical insulation property. In this specification, "the functional layer has electrical insulation property" means that the electrical resistivity in the thickness direction of the functional layer is 1×10 6 Ω·cm or more. The electrical resistivity may be measured using a known measuring device (for example, "Insulation Resistor 6517B" manufactured by Keithley Instruments, Inc., applied voltage 100V).

[0059] From the viewpoint of electrical insulation property, it is desirable that the functional layer has an electrical insulating material with a volume resistivity of 1×10 6 Ω·cm or more. Examples of the electrical insulating material include silicon carbide, titanium oxide, zirconia, kaolinite, mica, talc, silicon nitride, alumina, aluminum nitride, potassium titanate, and silica.

[0060] In addition, when the thermal conductivity of the functional layer is relatively low, it is effective in improving the heat insulation performance. In this case, the thermal conductivity of the functional layer is preferably 2.5 W / m·K or less. The thermal conductivity may be measured using a known measuring device (for example, "Thermal Conductivity Checker 'Quick Lambda HC-10'" manufactured by Eihiro Seiki Co., Ltd.). From the viewpoint of reducing the thermal conductivity of the functional layer, it is desirable for the functional layer to contain talc, montmorillonite, silica, mica, kaolinite, etc. having a thermal conductivity of 2.5 W / m·K or less. Note that the thermal conductivity of the functional layer is often higher than that of the heat insulation layer. Therefore, from the viewpoint of suppressing heat conduction, it is desirable that the thickness of the functional layer be relatively small, for example, 200 μm or less.

[0061] Summarizing the above, from the viewpoints of fire resistance and electrical insulation, it is desirable for the functional layer to have a form containing mica, kaolinite, silica, talc, zirconia, and titanium oxide. Further, considering radiant heat dissipation, it is desirable for the functional layer to have mica, kaolinite, and zirconia. In addition, the functional layer may contain other components such as a binder for binding the constituent materials. Note that the functional layer can be disposed not only on both sides in the thickness direction of the heat insulation layer but also on the end faces of the heat insulation layer and the like. For example, when the entire outside of the heat insulating material is covered with a functional layer having fire resistance and the like, the heat and flame blocking effect becomes higher and the safety is further improved.

[0062] (3) Radiation reflection layer As shown in the first to third embodiments above, the heat insulating material of the present disclosure may include a radiation reflection layer in addition to the heat insulation layer and the pair of functional layers. The radiation reflection layer mainly plays a role of reflecting the heat emitted from the heat source. Thereby, the heat insulation performance of the heat insulating material is further improved. In order to exhibit the heat reflection function, it is desirable that the radiation reflection layer be disposed at a distance from the heat source. The radiation reflection layer may be disposed outside the heat insulation layer, that is, on the heat source side of the heat insulation layer. However, it is more effective in heat insulation to reflect heat in the radiation reflection layer after suppressing heat transfer by conduction and convection to some extent in the heat insulation layer. Therefore, a form in which a heat insulation layer is interposed between the heat source and the radiation reflection layer is desirable. For example, a form in which the heat insulation layer is divided into two or more layers and the radiation reflection layer is disposed therebetween is desirable.

[0063] The radiation reflection layer may be formed using a material with a low emissivity such as a metal. For example, a form having a low-emissivity material with an emissivity of 0.2 or less is desirable. Examples of the low-emissivity material include aluminum, aluminum compounds, magnesium, magnesium compounds, silver, titanium, titanium compounds, tin, gold, copper, and the like. The shape of the radiation reflection layer is not particularly limited, such as foil, film, sheet, plate, etc. Examples of the radiation reflection layer include metal foil, metal vapor deposition film, metal paste dry film obtained by drying a metal paste, and metal plate. Among these, the metal vapor deposition film may be manufactured by vapor-depositing a metal on the surface of a resin film made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyethylene (PE), or the like by vacuum vapor deposition or sputtering. The metal paste dry film may be manufactured by applying a metal filler dispersion such as an aluminum paste on a substrate and drying it. From the viewpoints of handleability, strength, etc., the thickness of the radiation reflection layer is desirably 10 μm or more, and further desirably 20 μm or more. On the other hand, from the viewpoints of thinning, flexibility, etc., the thickness of the radiation reflection layer is desirably 200 μm or less, and further desirably 100 μm or less.

[0064] (4) Substrate As shown in the first and fourth embodiments above, the heat insulation material of the present disclosure may include a substrate for supporting a heat insulation layer and a functional layer. In the first and fourth embodiments above, two substrates were used, but the number, material, shape, etc. of the substrates are not particularly limited. For example, the substrate may be arranged only on one side of the heat insulation layer, or a single substrate may be folded back to wrap the heat insulation layer and the like to form a covering body.

[0065] Examples of the material of the base material include cloth, resin, paper, etc. Examples of the fiber constituting the cloth include glass fiber, rock wool, ceramic fiber, alumina fiber, silica fiber, carbon fiber, metal fiber, polyimide fiber, aramid fiber, polyphenylene sulfide (PPS) fiber, etc. Known ceramic fibers include refractory ceramic fiber (RCF), polycrystalline alumina fiber (Polycrystalline Wool: PCW), and alkali earth silicate (AES) fiber. Among them, AES fiber has higher safety because it has biocompatibility. Examples of the resin include polyethylene terephthalate (PET), polyimide, polyamide, PPS, etc. Examples of the paper include pulp, a composite material of pulp and magnesium silicate, etc. The shape of the base material is not particularly limited, and examples include woven fabric, non-woven fabric, film, sheet, etc. The base material may be composed of a single layer or a laminate in which the same material or different materials are laminated in two or more layers.

[0066] For example, fabrics (woven fabrics) made of inorganic fibers such as glass fiber and metal fiber, such as glass cloth, non-woven fabrics, and refractory heat-insulating paper made as a composite material of pulp and magnesium silicate, have relatively low thermal conductivity and high shape retention even in a high-temperature atmosphere. Also, when a base material with high heat resistance is adopted, it can be applied to applications that require high heat resistance, so the applications of the heat-insulating material of the present disclosure are expanded. Furthermore, when a base material with fire resistance is adopted, safety is further improved. The base material with high heat resistance may be manufactured from glass fiber, rock wool, ceramic fiber, polyimide, PPS, etc. Specifically, examples include glass fiber non-woven fabric, glass cloth, alumina glass cloth, AES wool paper, polyimide fiber non-woven fabric, etc.

[0067] (5) Others In order to increase the adhesive force between the layers, the heat-insulating material of the present disclosure may be provided with an adhesive layer between the layers. For example, in the heat-insulating materials of the second and third embodiments above, an adhesive layer may be interposed between the first and second heat-insulating layers and the radiation reflection layer. The adhesive layer may contain a flame retardant etc. in addition to the adhesive component.

[0068] [Method for manufacturing heat insulating material] As shown in the first and fourth embodiments above, the heat insulating material of the present disclosure can be manufactured by applying a composition for a heat insulating layer on one surface of a base material, drying it to form a heat insulating layer, applying a composition for a functional layer on the other surface of the same base material, and drying it to form a functional layer. Alternatively, a base material on which a functional layer has been previously formed may be used. Further, as shown in the second and third embodiments, the composition for the functional layer may be directly applied to the surface of the heat insulating layer and dried to form the functional layer. For application, brushing, coating machines such as a blade coater, a bar coater, a die coater, a comma coater (registered trademark), a roll coater, or a spray may be used. Alternatively, the heat insulating layer may be immersed in the composition for the functional layer. Drying may be performed at a temperature of 80 to 150°C for several minutes to several tens of minutes.

Example

[0069] Next, the present disclosure will be described more specifically with reference to examples.

[0070] [Manufacture of heat insulating material sample] [Sample A-1] A heat insulating material sample having the configuration of the fourth embodiment above was manufactured. The compositions of the heat insulating layer and the functional layer are shown in Table 1 below. First, silica aerogel, infrared shielding particles (SiC), reinforcing fibers (glass fibers), and a thickening agent (PEO) were put into a kneader ("Trimix (registered trademark)" manufactured by Inoue Seisakusho Co., Ltd.) and stirred and mixed for 1 minute. While continuing the stirring, water was added so that the solid content became 40 to 50%. Then, stirring and mixing were further performed for 15 minutes. Thereafter, every time stirring was performed for 2 minutes, the stirring was stopped, and while scraping off the materials adhering to the inner wall surface of the container, the blade surface, etc. with a spatula, additional stirring and mixing were performed for 30 minutes to manufacture a clay-like composition for the heat insulating layer. Separately, water was added to a urethane resin emulsion, and mica and ammonium polyphosphate were added thereto and stirred to prepare a composition for the functional layer.

[0071] Next, the prepared composition for the heat-insulating layer was applied onto the upper surface of the first substrate (glass cloth, thickness 100 μm) to form a coating film with a thickness of 2 mm, and then the second substrate (glass cloth, thickness 100 μm) was overlaid on the coating film. This laminate was placed in a mold and pressurized while heating to 150 °C to form a heat-insulating layer. Then, the prepared composition for the functional layer was applied onto the outer surfaces of the first substrate and the second substrate respectively, and dried at a temperature of about 100 °C to form a first functional layer and a second functional layer. The thicknesses of the first functional layer and the second functional layer are 200 μm, and the components and properties are the same. In this way, a heat-insulating material sample A-1 in which the first functional layer, the first substrate, the heat-insulating layer, the second substrate, and the second functional layer are laminated in the thickness direction was obtained.

[0072] [Sample A-2] A heat-insulating material sample A-2 was manufactured in the same manner as sample A-1, except that infrared shielding particles (SiC) were not blended in the heat-insulating layer and kaolinite was blended in the functional layer instead of mica.

[0073] [Samples B-1, B-2] For each of the heat-insulating material samples A-1 and A-2, heat-insulating material samples B-1 and B-2 having no first functional layer and second functional layer were manufactured. The heat-insulating material samples B-1 and B-2 are formed by laminating a first substrate, a heat-insulating layer, and a second substrate in the thickness direction.

[0074]

Table 1

[0075] <Evaluation of Heat-Insulating Material Samples> [Heat Insulation Property] (1) Evaluation Method The thermal conductivity of the manufactured heat insulating material sample was measured using the "Quick Thermal Conductivity Meter QTM-500" and "Probe PD-31" manufactured by Kyoto Electronics Industry Co., Ltd. First, with two heat insulating material samples stacked, the upper and lower sides of the probe were sandwiched, and a weight with a mass was placed on top so that the heat insulating material sample would not be crushed, and it was installed in a ceramic electric furnace ("ARF-30K" manufactured by Asahi Rika Seisakusho Co., Ltd.). Then, using a temperature controller ("AGC-S" manufactured by the same company), the furnace temperature was set to 800 ± 10 °C, and after 10 minutes had passed when the temperature had stabilized, the thermal conductivity was measured.

[0076] (2) Evaluation Results The evaluation results of the heat insulation performance based on the measurement results of the thermal conductivity are summarized in Table 1 above. For the evaluation of the heat insulation performance, if the thermal conductivity is less than 0.3 W / m·K, it is considered qualified (indicated by ○ in the table), and if the thermal conductivity is 0.3 W / m·K or more, it is considered unqualified (indicated by × in the table). As shown in Table 1, both Sample A-1 and A-2 had a thermal conductivity of less than 0.3 W / m·K, and it was confirmed that they had excellent heat insulation performance even in a high-temperature atmosphere of 800 °C. On the other hand, according to Sample B-2 without a functional layer, the thermal conductivity was 0.3 W / m·K or more, and the desired heat insulation performance in a high-temperature atmosphere could not be obtained. Although Sample B-1 also did not have a functional layer, its heat insulation performance was improved. This reason is considered to be that since the heat insulation layer has infrared shielding particles, the shielding effect of radiant heat was exerted.

Industrial Applicability

[0077] The heat insulating material of the present disclosure is suitable for heat insulating materials for vehicles, heat insulating materials for houses, heat insulating materials for electronic devices, heat insulating materials for heat preservation and cold storage containers, etc. Among them, it is preferably used for battery packs, heated cigarettes, fireproof heat insulating sheets, etc. that require heat insulation performance and fire resistance in a high-temperature atmosphere.

Explanation of Symbols

[0078] 10, 20, 30, 40: Heat insulating materials, 11: First heat insulating layer, 12: Second heat insulating layer, 13: First base material, 14: Second base material, 15: Radiation reflection layer, 16: First functional layer, 17: Second functional layer, 18: Third functional layer, 41: Heat insulating layer.

Claims

1. A heat insulation layer comprising a porous structure in which a plurality of particles are connected to form a skeleton, having pores inside, and having a hydrophobic site at least on the surface; and a thickener having polyethylene oxide. A pair of functional layers disposed on both sides in the thickness direction of the heat insulation layer. Comprising: The pair of functional layers have the same properties, and the properties include at least one of fire resistance and radiation heat dissipation with a surface emissivity of 0.6 or more. A heat insulating material characterized by this.

2. The pair of functional layers have a high emissivity material with an emissivity of 0.6 or more, and the heat insulating material according to claim 1 having radiation heat dissipation.

3. The pair of functional layers have a high melting point material with a melting point of 500 °C or more, and the heat insulating material according to claim 1 having fire resistance.

4. The pair of functional layers have electrical insulation properties, and the heat insulating material according to claim 1.

5. The pair of the functional layers is the heat insulating material according to claim 4, which has an electric insulating material with a volume resistivity of 1×10 ６ Ω·cm or more.

6. The thermal conductivity of the pair of functional layers is 2.5 W / m·K or less, and the heat insulating material according to claim 1.

7. The pair of functional layers have one or more selected from mica, kaolinite, silica, talc, zirconia, and titanium oxide, and the heat insulating material according to claim 1.

8. The heat insulation layer has a first heat insulation layer and a second heat insulation layer laminated in the thickness direction. Comprising a radiation reflection layer disposed between the first heat insulation layer and the second heat insulation layer. The pair of functional layers are disposed on the side opposite to the radiation reflection layer of the first heat insulation layer and on the side opposite to the radiation reflection layer of the second heat insulation layer, and the heat insulating material according to claim 1.

9. The radiation reflection layer has a low emissivity material with an emissivity of 0.2 or less, and the heat insulating material according to claim 8.

10. The radiation reflection layer is a metal foil, a metal vapor deposition film, or a metal paste dry film, and the heat insulating material according to claim 8 or claim 9.

11. The thickness of the heat insulation layer is 100 μm or more and 5000 μm or less, and the heat insulating material according to claim 1.

12. The heat insulation layer further has reinforcing fibers, and the heat insulating material according to claim 1.

13. The heat insulation layer further has infrared shielding particles, and the heat insulating material according to claim 1.

14. The porous structure is a silica aerogel in which a plurality of silica fine particles are connected to form a skeleton, and the heat insulating material according to claim 1.

15. The properties of the pair of functional layers are both fire resistance and radiation heat dissipation with a surface emissivity of 0.6 or more, and the heat insulating material according to claim 1.

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