Fire-resistant sheet, method for manufacturing the same, and battery

Abstract

[Problem] Provided are: a fire-spread prevention sheet capable of achieving elastic deformation that efficiently absorbs expansion of a heat source while achieving reflection of heat from the heat source; and a battery comprising the same.　[Solution] The present invention relates to: a fire-spread prevention sheet that is interposed between heat sources and is capable of preventing the spread of fire between the heat sources, and has a laminate structure having a plurality of layers, wherein a metal-film-equipped rubber sheet 17, in which a metal film 13 is provided on at least one surface in the thickness direction of a first rubber sheet 11, is provided inside the fire-spread prevention sheet in the thickness direction, and the metal film 13 is a film in which metal particles 15 are deposited; a method for manufacturing the fire-spread prevention sheet; and a battery.

Description

Cross-reference

[0001] This application claims priority under the Paris Convention based on Japanese Patent Application No. 2024-147066, filed in Japan on 29 August 2024, and all contents of said application are incorporated herein by reference. [Technical Field]

[0002] This invention relates to a fire-prevention sheet, a method for manufacturing the same, and a battery. [Background technology]

[0003] Automotive power is shifting from engines powered by fossil fuels such as gasoline and diesel to motors powered by electricity from batteries. In lithium-ion batteries, a type of battery, multiple battery cells (also simply called "cells") are typically arranged within the casing.

[0004] Battery cells can generate heat during charging and discharging. If a battery cell overheats, that heat can transfer to neighboring battery cells, resulting in the entire battery overheating and increasing the risk of fire. To prevent this, it is preferable to interpose materials that reduce heat conduction between battery cells. Conventionally, various methods have been considered to make it difficult for the heat of an overheated battery cell to be transferred to surrounding battery cells. For example, a method of providing a fire-resistant sheet such as a fire-resistant material or an insulating layer between multiple battery cells is known (see Patent Document 1).

[0005] On the other hand, when battery cells overheat, the battery cell containers expand. To absorb such expansion, it is preferable to interpose a material with high elastic deformation between battery cells. Prior to the present invention, the inventors of this applicant developed a fire-preventing sheet comprising a rubber sheet made of a rubber-like elastic material, heat-insulating sheets laminated on both sides of the rubber sheet that can reduce heat transfer between multiple adjacent heat sources, and an adhesive layer interposed between the rubber sheet and the heat-insulating sheets to bond the heat-insulating sheets to both sides of the rubber sheet (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-206604 [Patent Document 2] Japanese Patent Publication No. 2023-062546 [Overview of the project] [Problems that the invention aims to solve]

[0007] Based on the above-mentioned conventionally known knowledge of fire-spread prevention sheets, the inventors have conducted further development and have come up with the following improvements. One is to make it easier to reflect heat emitted from heat sources such as battery cells. The other is to enable the fire-spread prevention sheet to achieve elastic deformation that can more reliably absorb the expansion of the heat source.

[0008] When a laminated sheet, consisting of metal plates with high thermal conductivity, such as aluminum, placed on both sides of a rubber sheet in the thickness direction, is sandwiched between heat sources, the heat from the overheated heat sources is immediately transferred to the metal plates. As a result, the metal plates themselves become hot, which is undesirable. Furthermore, using ordinary metal plates inhibits the elastic deformation of the rubber sheets that make up the laminated sheet. Consequently, when the heat sources expand, the elastic deformation of the rubber cannot be performed in response to that expansion.

[0009] Based on the above findings, the present invention aims to provide a fire-spread prevention sheet and a battery equipped therewith that can achieve elastic deformation that efficiently absorbs the expansion of a heat source while reflecting heat from the heat source. [Means for solving the problem]

[0010] (1) A fire spread prevention sheet according to one embodiment for achieving the above objective is a fire spread prevention sheet that can be interposed between heat sources to prevent the spread of fire between heat sources, It has a laminate structure with multiple layers, The first rubber sheet is provided with a metal film on at least one side in the thickness direction of the first rubber sheet, inside the thickness direction of the fire-spread prevention sheet, The aforementioned metal film is a film in which metal particles are deposited. (2) In a fire-spread prevention sheet according to another embodiment, preferably the metal film may be formed 1 mm or more inward from both surfaces in the thickness direction of the fire-spread prevention sheet. (3) In another embodiment of the fire-spread prevention sheet, preferably the outer surface of the plurality of layers may be covered with an insulating film. (4) In a fire-spread prevention sheet according to another embodiment, preferably the first rubber sheet may be a sponge-like porous sheet. (5) In a fire-spread prevention sheet according to another embodiment, preferably the first rubber sheet may be silicone rubber. (6) In a fire-preventing sheet according to another embodiment, preferably the plurality of layers further comprises a second rubber sheet, the second rubber sheet being positioned opposite the metal film-bearing surface of the metal film-bearing rubber sheet. (7) In a fire-spread prevention sheet according to another embodiment, preferably at least one of the first rubber sheet and the second rubber sheet may be a sponge-like porous sheet. (8) In a fire-spread prevention sheet according to another embodiment, preferably at least one of the first rubber sheet and the second rubber sheet may be silicone rubber. (9) In a fire spread prevention sheet according to another embodiment, preferably, the metal film may be a thin film mainly composed of aluminum, copper, silver or gold, or a thin film of an alloy containing at least one element selected from aluminum, copper, silver and gold. (10) A fire spread prevention sheet according to another embodiment may preferably further include a metal oxide-containing heat insulating sheet on the metal film side of the rubber sheet with a metal film. (11) A fire spread prevention sheet according to another embodiment may preferably further include a second rubber sheet on a side of the heat insulating sheet opposite to the metal film. (12) In a fire spread prevention sheet according to another embodiment, preferably, a metal oxide-containing heat insulating sheet may be provided on at least one outer side in the thickness direction of the fire spread prevention sheet. (13) A method for manufacturing a fire spread prevention sheet according to an embodiment for achieving the above object is a method of manufacturing a fire spread prevention sheet that is interposed between heat sources to prevent fire spread between the heat sources, the fire spread prevention sheet has a laminated structure with a plurality of layers, the manufacturing method includes: a metal film forming step of forming a metal film with deposited metal particles on at least one surface in the thickness direction of a first rubber sheet that is one of the plurality of layers, to produce a rubber sheet with a metal film, and a laminating step of laminating the first rubber sheet and one or two other layers. (14) In a method for manufacturing a fire spread prevention sheet according to another embodiment, preferably, a covering step of covering the outside of the plurality of layers with an insulating film may be performed after the laminating step. (15) In a method for manufacturing a fire spread prevention sheet according to another embodiment, preferably, the one or two other layers may include a second rubber sheet. (16) In a method for manufacturing a fire spread prevention sheet according to another embodiment, preferably, the one or two other layers may include a metal oxide-containing heat insulating sheet. ​(17) In a method for manufacturing a fire-spread prevention sheet according to another embodiment, preferably the metal film formation step may be carried out by a metal deposition or sputtering process. (18) In a method for manufacturing a fire-preventing sheet according to another embodiment, preferably, prior to the metal film formation step, a primer treatment step may be performed on one side of the first rubber sheet in the thickness direction to facilitate the formation of the metal film. (19) A battery according to one embodiment for achieving the above objective is A battery that has multiple battery cells arranged in a row, One of the aforementioned fire-prevention sheets is interposed between the battery cells, which serve as heat sources. (20) A fire-spread prevention sheet according to one embodiment for achieving the above objective is a sheet that can be interposed between heat sources to prevent the spread of fire between heat sources, and has a laminate structure in which a metal film is sandwiched between a first rubber sheet and a second rubber sheet, wherein the metal film is a film in which metal particles are deposited. (21) In a fire-spread prevention sheet according to another embodiment, preferably at least one of the first rubber sheet and the second rubber sheet is a sponge-like porous sheet. (22) In a fire-spread prevention sheet according to another embodiment, preferably at least one of the first rubber sheet and the second rubber sheet may be silicone rubber. (23) In a fire-spread prevention sheet according to another embodiment, preferably the metal film may be one or more films of aluminum, copper, tin, or an alloy containing at least one of these elements. (24) A method for manufacturing a fire-preventing sheet according to one embodiment for achieving the above objective is a method for manufacturing any of the above-described fire-preventing sheets, comprising a metal film forming step of forming a metal film on one side in the thickness direction of a first rubber sheet, and a lamination step of laminating a second rubber sheet onto the metal film surface of the first rubber sheet. (25) In a method for manufacturing a fire-spread prevention sheet according to another embodiment, preferably, prior to the metal film formation step, a primer treatment step may be performed on one side of the first rubber sheet in the thickness direction to facilitate the formation of the metal film. (26) In a method for manufacturing a fire-spread prevention sheet according to another embodiment, preferably the metal film formation step may be carried out by a metal deposition or sputtering process. (27) A battery according to one embodiment for achieving the above objective is a battery comprising a plurality of battery cells arranged in a row, wherein one of the above-mentioned fire-spread prevention sheets is interposed between the battery cells. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a fire-spread prevention sheet that can reflect heat from a heat source while also achieving elastic deformation that efficiently absorbs the expansion of the heat source, and a battery equipped therewith. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows an enlarged view of the main part and a part A of the battery according to the first embodiment of the present invention. [Figure 2] Figure 2 shows a perspective view of a fire-spread prevention sheet according to the first embodiment of the present invention. [Figure 3] Figure 3 shows the main manufacturing process of the fire-spread prevention sheet shown in Figure 2. [Figure 4] Figure 4 shows the first step in the manufacturing process of the fire-spread prevention sheet shown in Figure 2. [Figure 5] Figure 5 shows the next step following the state shown in Figure 4. [Figure 6] Figure 6 shows the next step following the state shown in Figure 5. [Figure 7] Figure 7 shows the evaluation method (7A) and evaluation results (7B) of an example of a fire spread prevention sheet according to the first embodiment. [Figure 8] Figure 8 shows a disassembled and assembled perspective view of the fire-spread prevention sheet according to the second embodiment. [Figure 9] Figure 9 shows the main manufacturing process of the fire-spread prevention sheet shown in Figure 8. [Figure 10] Figure 10 shows a disassembled and assembled perspective view of the fire spread prevention sheet according to the third embodiment. [Figure 11] Figure 11 shows the main manufacturing process of the fire-spread prevention sheet shown in Figure 10. [Figure 11A] Figure 11A shows a disassembled and assembled perspective view of the fire-spread prevention sheet according to the fourth embodiment. [Figure 11B] Figure 11B shows a disassembled and assembled perspective view of a fire-spread prevention sheet with a different structure from that of Figure 11A. [Figure 11C] Figure 11C shows a disassembled and assembled cross-sectional view and an assembled cross-sectional view of a fire-spread prevention sheet comprising a metal-filmed rubber sheet in which a metal film is formed on both sides in the thickness direction of the first rubber sheet. [Figure 11D] Figure 11D shows a longitudinal cross-sectional view illustrating the laminated structure of a fire-spread prevention sheet according to another modified example. [Figure 11E] Figure 11E shows the main manufacturing process of the fire-resistant sheet shown in Figure 11D. [Figure 12] Figure 12 shows schematic diagrams of the layer structure of the foamed silicone rubber sheets of Examples 1 and 2 and Comparative Examples 1 and 2. [Figure 13] Figure 13 shows a photograph of a thermal resistance measuring device used to investigate the thermal resistance and thermal conductivity of three samples from Examples 1 and 2 and Comparative Example 1. [Figure 14] Figure 14 shows photographs of each sample A, B, and C sandwiched between the upper rod (Reference material) and the lower rod (Reference material). [Figure 15]Figure 15 shows a schematic diagram of the sample sandwiched between the upper and lower rods. (15A) shows the heat flow from the heat source to the upper rod, sample, lower rod, and heat sink (cooling section), the compression of the sample between the upper and lower rods, and the locations where the four thermocouples are fixed. (15B) shows the existence of the thermal resistance of the sample itself (Rth, Bulk), the thermal resistance between the sample and the upper rod (Rth, contact Ref-sample), and the thermal resistance between the sample and the lower rod (Rth, contact Ref-sample), as well as the formula for measuring thermal conductivity. [Figure 16] Figure 16 shows the changes in thermal resistance (16A) and thermal conductivity (16B) when the pressure applied to sample A of Example 1, sample B of Example 2, and sample C of Comparative Example 1 is increased. [Figure 17] Figure 17 shows a graph of the relationship between thickness and stress when sample A from Example 1, sample C from Comparative Example 1, and sample D from Comparative Example 2 are compressed in the thickness direction. [Figure 18] Figure 18 shows an optical microscope image (magnification during observation: 500x) of the thin aluminum film of sheet a, which constitutes sample A. [Figure 19] Figure 19 shows scanning electron microscope images of the aluminum thin film of sheet a (magnifications at 1000x, 3000x, and 10000x). [Explanation of Symbols]

[0013] 1...Battery, 5...Battery cell (example of heat source), 10, 10a, 10b, 10c, 10d, 10e, 10f...Fire prevention sheet, 11...First rubber sheet (e.g., sponge-like porous sheet), 12...Second rubber sheet (e.g., sponge-like porous sheet), 13...Metal film, 14...Pores, 15...Metal particles, 17...Rubber sheet with metal film, 31, 32...Insulation sheet. [Modes for carrying out the invention]

[0014] Next, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below are not intended to limit the invention as defined in the claims, and not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0015] <First Embodiment> First, a fire-spread prevention sheet, a method for manufacturing the fire-spread prevention sheet, and a battery according to the first embodiment of the present invention will be described.

[0016] Figure 1 shows an enlarged view of the main part and a part A of the battery according to the first embodiment of the present invention.

[0017] The battery 1 according to this embodiment is, for example, a battery for an electric vehicle, and is preferably a lithium-ion battery. The battery 1 is equipped with a number of battery cells (also simply called "cells") 5 arranged in a row, with a fire-spread prevention sheet 10 sandwiched between the battery cells 5. The fire-spread prevention sheet 10 is designed to minimize the spread of fire to adjacent battery cells 5 even if some of the battery cells 5 become overheated and, in the worst case, ignite. The fire-spread prevention sheet 10 is also elastically deformable in the direction of its thickness. Multiple battery cells 5 are compressed in the direction in which they are arranged and set inside the battery 1. At this time, the fire-spread prevention sheet 10 is compressed and deformed by the compression from the battery cells 5. On the other hand, when the compression from the multiple battery cells 5 is released, the fire-spread prevention sheet 10 returns to its original thickness. Furthermore, the fire-spread prevention sheet 10 is elastically deformable in accordance with the deformation of the battery cells 5 when the battery cells 5, which are an example of a heat source, expand due to heat.

[0018] Figure 2 shows a perspective view of a fire-spread prevention sheet according to the first embodiment of the present invention.

[0019] The fire-spread prevention sheet 10 according to this embodiment is a sheet that can be interposed between battery cells 5, which are an example of a heat source, to prevent the spread of fire between the battery cells 5, and has a laminate structure having multiple layers. Many fire-spread prevention sheets 10 are provided inside the battery 1 so that both sides in the thickness direction are in contact with the battery cells 5. However, at least one of the multiple fire-spread prevention sheets 10 may be provided inside the battery 1 so that one side in the thickness direction is in contact with the battery cells 5, and the opposite side is in contact with the housing (not shown) of the battery 1.

[0020] The fire-spread prevention sheet 10 in this embodiment has a laminate structure in which a metal film 13 is sandwiched between a first rubber sheet 11 and a second rubber sheet 12. The second rubber sheet 12 is one of several layers that make up the laminate structure. The second rubber sheet 12 is positioned opposite the surface of the metal film-attached rubber sheet 17 (first rubber sheet 11 + metal film 13), which will be described later, that has the metal film 13. The metal film 13 is a thin film formed on the first rubber sheet 11, more specifically a film in which metal particles are deposited. In this application, metal particles are broadly interpreted to include metal atoms.

[0021] The thicknesses of the first rubber sheet 11 and the second rubber sheet 12 may be relatively larger or the same, but are preferably the same. As a result, the metal film 13 is positioned exactly in the middle of the thickness of the fire-preventing sheet 10. There are no particular restrictions on the range of thicknesses of the first rubber sheet 11 and the second rubber sheet 12, but are preferably 0.5 mm to 10 mm, more preferably 1 mm to 7 mm. The metal film 13 has a form in which one or more layers of metal particles are deposited.

[0022] The first rubber sheet 11 and the second rubber sheet 12 are configured to include, for example, thermosetting elastomers such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, nitrile rubber (NBR), or styrene butadiene rubber (SBR); thermoplastic elastomers such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based, and fluorine-based elastomers, or composites thereof. Silicone rubber sheets with excellent heat resistance are preferred as the first rubber sheet 11 and the second rubber sheet 12. The first rubber sheet 11 and the second rubber sheet 12 may also contain fillers such as silica and graphite. Furthermore, porous sheets with high elasticity (also called sponge-like porous sheets) are preferred as the first rubber sheet 11 and the second rubber sheet 12. In this embodiment, porous sheets made of silicone rubber (also called foamed silicone rubber sheets) are used as a more preferred form of the first rubber sheet 11 and the second rubber sheet 12. The thermal insulation properties of the sheets can be further enhanced by having small air pockets inside the first rubber sheet 11 and the second rubber sheet 12.

[0023] Furthermore, the first rubber sheet 11 and the second rubber sheet 12 do not necessarily have to be made of the same type of rubber. For example, either the first rubber sheet 11 or the second rubber sheet 12 may be made of silicone rubber, and the other may be made of non-silicone rubber. Alternatively, either the first rubber sheet 11 or the second rubber sheet 12 may be a sponge-like porous sheet, and the other may be a non-sponge sheet.

[0024] The metal film 13 is not limited to any particular type of metal, but is preferably a thin film mainly composed of aluminum, copper, tin, silver, or gold, or a thin film of an alloy containing at least one of the elements aluminum, copper, tin, silver, or gold. The metal film 13 may be a film of one type of metal component, or a film in which films of two types of metal components are laminated. The metal film 13 may be, for example, a film of aluminum, a film of copper, a film of tin, a film of silver, a film of gold, a film of aluminum alloy, a film of copper alloy, a film of tin alloy, a film of silver alloy, or a film in which two or more of the above films are laminated. The metal film 13 is a thin film in which metal particles (preferably crystal grains) are formed in an island-like or scale-like manner, and is different from a metal film or metal sheet formed by rolling or the like. As can be seen from the exemplary thickness described above, the metal film 13 is very thin. Therefore, the risk of the metal film 13 hindering the elastic deformation of the fire-spread prevention sheet 10 in the thickness direction can be reduced. The thickness of the metal film 13 is preferably 50 nm to 700 nm, more preferably 60 nm to 600 nm, even more preferably 100 nm to 500 nm, and particularly more preferably 100 nm to 300 nm. The metal film 13 is located inside the fire-prevention sheet 10 in the thickness direction and not on the outer surface of the fire-prevention sheet 10 in the thickness direction. It is preferable that the metal film 13 is formed at least 1 mm inside both surfaces in the thickness direction of the fire-prevention sheet 10 (thickness: preferably 4 to 10 mm, more preferably 5 to 8 mm). This is also true for subsequent fire-prevention sheets 10a, 10b, 10c, 10d, 10e, and 10f. The metal film 13 is a film formed on the sheet surface from within the pores of the sponge-like sheet (porous sheet), and is not a film fixed only to the sheet surface. The metal portion in the pores of the metal film 13 is an extremely fine needle-like portion that enhances the adhesion force between the film and the sheet. In other words, the metal film 13 has a shape like a pincushion, with a portion of it inserted into the holes of the sheet. Therefore, against the continuous expansion of the porous sheet, the metal film 13 is less likely to peel off as it follows the deformation of the porous sheet.

[0025] Figure 3 shows the main manufacturing process of the fire-resistant sheet shown in Figure 2. Figures 4-6 show the manufacturing process of the fire-resistant sheet shown in Figure 2 in stepwise perspective views. Figure 5 shows a magnified view of a portion B1 in the metal film 13, and further magnified B2 within B1.

[0026] The method for manufacturing the fire-spread prevention sheet 10 according to this embodiment preferably includes a primer treatment (S100), a metal film formation step (S200), and a first lamination step (S300) as a lamination step, as shown in Figure 3. The primer treatment is an optional step and is not a required step.

[0027] (1) Primer treatment (S100) This step is a step that facilitates the formation of a metal film 13 on one side in the thickness direction of the first rubber sheet 11 prior to the metal film formation step (S200). Various primer treatments can be selected depending on the material of the first rubber sheet 11. For example, when the first rubber sheet 11 is silicone rubber, the application of a silane coupling agent can be exemplified as a primer treatment. Examples of silane coupling agents include epoxy-functional alkoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; mercapto-functional alkoxysilanes such as γ-mercaptopropyltrimethoxysilane; amine-functional alkoxysilanes such as γ-aminopropyltrimethoxysilane and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; and methacrylic-functional alkoxysilanes such as 3-methacryloxypropyltrimethoxysilane.

[0028] (2) Metal film formation process (S200) This process, as shown in Figure 5, is a process for manufacturing a rubber sheet with a metal film, in which metal particles 15 are deposited on at least one side in the thickness direction of a first rubber sheet 11, which is one of the multiple layers constituting the fire-spread prevention sheet 10. If the primer treatment process (S100) is performed, the metal film 13 is formed on the primer-treated surface of the first rubber sheet 11. The metal film formation process (S200) is preferably performed by metal deposition or sputtering. Deposition is a method in which a metal is heated in a vacuum chamber and evaporated to form a metal film 13 on one side of the first rubber sheet 11. Examples of methods for depositing metal include resistance heating, electron beam irradiation, laser heating, and high-frequency induction. Sputtering is a method in which an inert gas such as argon is used as an ion to collide with a metal target in a vacuum chamber, causing metal atoms to fly out from the target and form a metal film 13 on the first rubber sheet 11. For the metal film formation process (S200), sputtering, which allows for relatively high-density film formation, is preferred. The preferred vacuum level in the vacuum chamber before sputtering is 8 × 10⁻⁶. ―4 The pressure is less than or equal to Pa. Examples of sputtering types include magnetron sputtering, RF sputtering, reactive sputtering, DC sputtering, and two-electrode sputtering.

[0029] As shown in the enlarged view of part B1 and part B2 of Figure 5, the metal film 13 is a film in which metal particles 15 are deposited. When the first rubber sheet 11 is a sponge-like porous sheet, the metal film 13 is formed on the outermost surface of the first rubber sheet 11. The first rubber sheet 11 also has holes 14 that are recessed inward on its outermost surface. The metal particles 15 enter into the holes 14 or are deposited in a way that blocks the holes 14. For this reason, the metal film 13 is formed on the first rubber sheet 11 in a form that extends from the outermost surface of the first rubber sheet 11 into the holes 14.

[0030] (3) First lamination process (S300) This step involves laminating the first rubber sheet 11 with one or two other layers. In this embodiment, the first lamination step is a lamination step in which a second rubber sheet 12, which is an example of another layer, is laminated onto the metal film 13 surface of the first rubber sheet 11, as shown in Figure 6. Prior to this step, the surface of the second rubber sheet 12 that is in contact with the metal film 13 may be treated in the same way as the primer treatment step (S100). In addition, heating, or a combination of heating and pressurizing, may be performed in the first lamination step (S300). Furthermore, lamination may be performed using a heat-resistant adhesive.

[0031] Next, I will explain the preliminary experiments.

[0032] Figure 7 shows the evaluation method (7A) and evaluation results (7B) of an example of a fire spread prevention sheet according to the first embodiment. In graph (7B), the horizontal axis represents elapsed time (sec), and the vertical axis represents temperature (°C).

[0033] The fire spread prevention performance was tested by placing sample X between a heating element (800°C) 20 and a temperature measuring plate 21, as shown in (7A), and applying pressure between the heating element 20 and the temperature measuring plate 21 when the heating element reached 800°C. The pressure applied was 0.1 MPa. The temperature was measured at the position of the temperature measuring plate 21. Three types of samples were used for sample X. The first sample was a 4.2 mm thick foamed silicone rubber sheet (specific gravity: 0.36) used as a comparative material (Sample A). The second sample was a sheet used as an example of this embodiment (Sample B), which is a sheet in which a laminated film of a 1 μm thick copper thin film and a 0.3 μm thick tin alloy (Sn-Ag-P alloy) thin film is sandwiched between two 2.1 mm thick foamed silicone rubber sheets (specific gravity: 0.36). The copper thin film was formed by vapor deposition on one side of the 2.1 mm thick foamed silicone rubber sheet. The thin film of the tin alloy described above was formed by vapor deposition on the surface of a thin film of copper. Vacuum deposition was performed using a batch deposition system (model: LP1300BSD) manufactured by ULVAC, with a vacuum level of 1 × 10⁻⁶ in the chamber. ―4 ~1 × 10 ―6The experiment was conducted within the range of Pa. Furthermore, the deposition was performed by heating the metal for deposition using a resistance heating method. The third sample was a sheet used as a comparative material (Sample C), consisting of a 10 μm thick aluminum foil sandwiched between two 2.1 mm thick foamed silicone rubber sheets (specific gravity: 0.36). Note that the foamed silicone rubber sheet is also referred to as silicone sponge.

[0034] As shown in (7B), Sample A, Sample B, and Sample C all showed a temperature increase over time. Since all samples maintained a temperature below 400°C, they demonstrated a significant temperature rise suppression effect compared to the temperature of the heating element (800°C). Furthermore, it was found that Sample B showed a greater temperature rise suppression effect than Sample A. In addition, Sample C showed a greater temperature rise suppression effect than Sample B. However, in the case of a structure like Sample C, in which aluminum foil is sandwiched between foamed silicone rubber sheets, it was found that it was difficult to compress even when the load was concentrated in the center of the laminated sheet. This is thought to be because the aluminum foil does not stretch easily, and therefore the foil suppressed the deformation of the foamed silicone rubber sheet. This phenomenon was not observed in the structure of Sample B. From these results, it was determined that Sample B, which has a relatively large heat shielding effect and suppresses the deformation of the silicone rubber as little as possible, is an overall superior structure.

[0035] <Second Embodiment> Next, a fire-spread prevention sheet, a method for manufacturing the fire-spread prevention sheet, and a battery according to a second embodiment of the present invention will be described. In the second embodiment, the description of parts common to the first embodiment will be omitted as appropriate.

[0036] Figure 8 shows a disassembled and assembled perspective view of the fire-spread prevention sheet according to the second embodiment.

[0037] The fire-spread prevention sheet 10a according to the second embodiment has a structure in which a laminate of a metal-film-coated rubber sheet 17 and a second rubber sheet 12 is sandwiched between heat insulating sheets 31 and 32 from an even outerter surface than the fire-spread prevention sheet 10 according to the first embodiment. Here, the heat insulating sheets 31 and 32 are sheets containing metal oxides and have the function of enhancing the heat insulating properties of the fire-spread prevention sheet 10a by being present on both sides in the thickness direction of the laminate. Preferably, the heat insulating sheets 31 and 32 are sheets mainly containing talc, diatomaceous earth, silica, aerogel (e.g., silica aerogel), mullite, cordierite, steatite, forsterite, titania, or zirconia, and more preferably sheets mainly containing talc, diatomaceous earth, silica, or aerogel. Talc is generally a ceramic mainly composed of hydrated magnesium silicate and contains small amounts of impurities such as iron oxide. The type and amount of impurities vary depending on the origin of the talc ore, but the talc contained in the heat insulating sheets 31 and 32 is not particularly limited in that respect.

[0038] The term "primarily" above means that the ratio of the mass of metal oxides such as talc, diatomaceous earth, silica, aerogel, mullite, cordierite, steatite, forsterite, titania, or zirconia to the total mass of the heat insulating sheets 31 and 32 exceeds 50% by mass. The content of the metal oxide in the total heat insulating sheets 31 and 32 is preferably 51% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. In addition to the above metal oxides, the heat insulating sheets 31 and 32 may also contain relatively heat-resistant materials such as silicone rubber, aramid fibers, and polyphenylene sulfide. Furthermore, the heat insulating sheets 31 and 32 may be composed almost entirely or entirely of the above metal oxides. There are no particular restrictions on the manufacturing method of the heat insulating sheets 31 and 32, but examples include a manufacturing method that includes a process similar to the papermaking process included in the paper manufacturing process, a method of molding the heat insulating sheet material by placing it in a mold, and a method of shaping a molten material containing the material into a sheet shape using a 3D printer.

[0039] Figure 9 shows the main manufacturing process of the fire-spread prevention sheet shown in Figure 8.

[0040] The method for manufacturing a fire-resistant sheet according to this embodiment preferably includes, as shown in Figure 9, a metal film formation step (S200), a first lamination step (S300) which is the first of two lamination steps, and a second lamination step (S400) which is the second of two lamination steps. Similar to the method for manufacturing a fire-resistant sheet according to the first embodiment, the method for manufacturing a fire-resistant sheet according to the second embodiment may optionally include a primer treatment (S100).

[0041] The metal film formation process (S200) and the first lamination process (S300) are the same as in the first embodiment, so redundant explanations will be omitted.

[0042] Second lamination process (S400) This process is one of the lamination processes for laminating a first rubber sheet 11 with one or two other layers, and involves laminating a laminate in which a second rubber sheet 12 is laminated on the metal film 13 surface of a metal film-attached rubber sheet 17, and then laminating the laminate by sandwiching it between heat insulating sheets 31 and 32 on both sides in the thickness direction. The heat insulating sheets 31 and 32 and the rubber sheets 11 and 12 can be fixed by any method, but for example, they can be fixed using an adhesive.

[0043] Furthermore, instead of laminating the thermal insulation sheets 31 and 32 after the completion of the above-mentioned laminate, the thermal insulation sheets 31 and 32 may be attached to the rubber sheets 11 and 12 before laminating the first rubber sheet 11 and the second rubber sheet 12, or before forming the metal film 13. Therefore, in the flow of Figure 9, the second lamination process (S400) can also be performed immediately before the metal film formation process (S200) or immediately before the first lamination process (S300). Thus, the second lamination process can be divided into the process of laminating the thermal insulation sheet 31 onto the first rubber sheet 11 and the process of laminating the thermal insulation sheet 32 ​​onto the second rubber sheet 12.

[0044] The battery according to the second embodiment has the same configuration as battery 1 according to the first embodiment. Therefore, a description of the battery according to the second embodiment will be omitted.

[0045] <Third Embodiment> Next, a fire-spread prevention sheet, a method for manufacturing the fire-spread prevention sheet, and a battery according to the third embodiment of the present invention will be described. In the third embodiment, the description of parts common to the first or second embodiment will be omitted as appropriate.

[0046] Figure 10 shows a disassembled and assembled perspective view of the fire spread prevention sheet according to the third embodiment.

[0047] The fire-spread prevention sheet 10b according to the third embodiment has a structure that is the same as the fire-spread prevention sheet 10a according to the second embodiment, but without the second rubber sheet 12. That is, it has a structure in which a first rubber sheet 11, on which a metal film 13 is formed on one side, is sandwiched between heat insulating sheets 31 and 32 on both sides in the thickness direction. Therefore, one side of the metal film 13 is in contact with the first rubber sheet 11, but the other side of the metal film 13 is in contact with the heat insulating sheet 32. An adhesive layer may be interposed between the metal film 13 and the heat insulating sheet 32. The composition and manufacturing method of the heat insulating sheets 31 and 32 are the same as those described in the second embodiment.

[0048] Figure 11 shows the main manufacturing process of the fire-spread prevention sheet shown in Figure 10.

[0049] The method for manufacturing the fire-resistant sheet according to this embodiment preferably includes a metal film formation step (S200) and a second lamination step (S400), as shown in Figure 11. Similar to the method for manufacturing the fire-resistant sheet according to the first embodiment, the method for manufacturing the fire-resistant sheet according to the third embodiment may optionally include a primer treatment (S100).

[0050] The metal film formation process (S200) is the same as in the first embodiment, so a redundant explanation will be omitted.

[0051] Second lamination process (S400) This process is a type of lamination process in which heat insulating sheets 31 and 32 are attached to both sides in the thickness direction of the metal-filmed rubber sheet 17, which has a metal film 13 formed on one side of the first rubber sheet 11. The heat insulating sheets 31 and 32 and the metal-filmed rubber sheet 17 can be fixed by any method, but for example, they can be fixed using an adhesive. In addition, part of the second lamination process (S400) may be performed before the metal film formation process (S200). In that case, the heat insulating sheet 31 can be attached to one side of the first rubber sheet 11, and then the metal film 13 can be formed on the side of the first rubber sheet 11 opposite to the heat insulating sheet 31, and the heat insulating sheet 32 ​​can be attached to the side with the metal film 13.

[0052] The battery according to the third embodiment has the same configuration as the battery 1 according to the first embodiment. Therefore, a description of the battery according to the third embodiment will be omitted.

[0053] <Fourth Embodiment> Next, a fire-spread prevention sheet, a method for manufacturing the fire-spread prevention sheet, and a battery according to the fourth embodiment of the present invention will be described. In the fourth embodiment, the description of parts common to the first, second, or third embodiment will be omitted as appropriate.

[0054] Figure 11A shows a disassembled and assembled perspective view of a fire-spread prevention sheet according to the fourth embodiment. Figure 11B shows a disassembled and assembled perspective view of a fire-spread prevention sheet with a different structure from that of Figure 11A.

[0055] The fire-spread prevention sheet 10c according to the fourth embodiment includes a metal oxide-containing heat-insulating sheet 32 ​​on the metal film 13 side of the metal film-coated rubber sheet 17. The fire-spread prevention sheet 10d according to a modified example of the fourth embodiment includes a second rubber sheet 12 on the side of the heat-insulating sheet 32 ​​opposite to the metal film 13.

[0056] In other words, the fire-spread prevention sheet 10c has a structure obtained by removing the heat insulating sheet 31 from the fire-spread prevention sheet 10b according to the third embodiment. An adhesive layer may be interposed between the metal film 13 and the heat insulating sheet 32. The structure and manufacturing method of the heat insulating sheet 32 ​​are the same as those described in the second embodiment.

[0057] The fire-spread prevention sheet 10d has a structure that further includes a second rubber sheet 12 in addition to the heat insulating sheet 32 ​​of the fire-spread prevention sheet 10c according to the fourth embodiment described above. That is, the fire-spread prevention sheet 10d has a structure in which a rubber sheet with a metal film 17, a heat insulating sheet 32 ​​arranged on the side of the metal film 13, and a second rubber sheet 12 are laminated in that order. An adhesive layer may be interposed between the heat insulating sheet 32 ​​and the second rubber sheet 12.

[0058] The method for manufacturing the fire-spread prevention sheet 10c according to the fourth embodiment preferably includes a metal film formation step (S200) and a second lamination step (S400), similar to that shown in Figure 11. The metal film formation step (S200) is the same as that of the first embodiment, so a redundant explanation will be omitted.

[0059] The second lamination step (S400) differs slightly from the third embodiment in that it is a step of attaching the heat insulating sheet 32 ​​to the metal film 13 side of the metal film-coated rubber sheet 17, which has the metal film 13 formed on one side of the first rubber sheet 11. The heat insulating sheet 31 does not exist. The heat insulating sheet 32 ​​and the metal film-coated rubber sheet 17 can be fixed by any method, but for example, they can be fixed using an adhesive.

[0060] A modified version of the fourth embodiment is a method for manufacturing the fire-spread prevention sheet 10d, in which the first lamination step (S300) and the second lamination step (S400) are performed in reverse order in the process shown in Figure 9, and the second lamination step (S400) is the same as the second lamination step (S400) in the fourth embodiment, i.e., only the heat insulating sheet 32 ​​is attached.

[0061] The battery according to the fourth embodiment has the same configuration as battery 1 according to the first embodiment. Therefore, a description of the battery according to the fourth embodiment will be omitted.

[0062] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified in various ways.

[0063] In the above-described embodiment, both the first rubber sheet 11 and the second rubber sheet 12 are sponge-like porous sheets, but either one of the rubber sheets 11 or 12 may be a sponge-like porous sheet. Alternatively, both rubber sheets 11 and 12 may be non-sponge-like rubber sheets.

[0064] In the embodiment described above, the metal film 13 is formed over the entire area of ​​one side of the first rubber sheet 11. However, the metal film 13 may be formed over one or more areas on a part of that one side.

[0065] Furthermore, the metal film 13 may be formed on both sides of the first rubber sheet 11 in the thickness direction.

[0066] Figure 11C shows a disassembled and assembled cross-sectional view and an assembled cross-sectional view of a fire-spread prevention sheet comprising a metal-filmed rubber sheet in which a metal film is formed on both sides in the thickness direction of the first rubber sheet.

[0067] The fire-spread prevention sheet 10e shown in Figure 11C comprises a metal-filmed rubber sheet 17 having a metal film 13 formed on both sides in the thickness direction of the first rubber sheet 11, and heat insulating sheets 31 and 32 sandwiching the metal-filmed rubber sheet 17 from both sides in the thickness direction. The fire-spread prevention sheet 10e is provided with the metal film 13 on both sides in the thickness direction, whereas in the fire-spread prevention sheet 10b according to the third embodiment, the metal film 13 is provided only on one side in the thickness direction of the first rubber sheet 11.

[0068] Figure 11D shows a longitudinal cross-sectional view illustrating the laminated structure of a fire-spread prevention sheet according to another modified example. Figure 11E shows the main manufacturing process of the fire-spread prevention sheet shown in Figure 11D.

[0069] Another modified example of the fire-spread prevention sheet 10f includes an insulating film 40 that covers the outside of multiple layers constituting the fire-spread prevention sheet. The fire-spread prevention sheet 10f has a structure in which the outside of the aforementioned fire-spread prevention sheet 10e is covered with the insulating film 40. However, the insulating film 40 may also cover the outside of the other fire-spread prevention sheets 10, 10a, 10b, 10c, and 10d.

[0070] The insulating film 40 has the function of reducing the risk of electrical current flow between the fire-prevention sheets 10, 10a, 10b, 10c, 10d, 10e and the equipment (including battery 1) equipped therewith. The insulating film 40 is not particularly limited as long as it is made of a resin with excellent insulating properties, for example, olefin resins represented by polyethylene (PE) and polypropylene (PP); polyester resins represented by polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); and other resins such as polycarbonate (PC) and polyurethane (PU). Preferably, the insulating film 40 has a bag-like form that covers the entirety of multiple layers. The insulating properties of the insulating film 40 are preferably expressed as a volume resistivity of 10 8 ~10 18 It is Ω·cm.

[0071] In the method for manufacturing the fire-resistant sheet 10f, as shown in Figure 11E, preferably, a metal film formation step (S200) and a second lamination step (S400) are performed, and after the completion of lamination, a coating step (S500) is performed. The coating step (S500) is performed after the step of forming the metal film 13 and the lamination step of laminating the first rubber sheet 11 with one or two other layers, even when coating other fire-resistant sheets 10, 10a, 10b, 10c, and 10d. The method for manufacturing the fire-resistant sheet 10f may optionally include a primer treatment (S100).

[0072] The fire-preventing sheets 10, 10a, 10b, 10c, 10d, 10e, and 10f may be placed not only between the battery cells 5, but also between the battery cells 5 and the housing that encloses them. Furthermore, the fire-preventing sheets 10, 10a, 10b, 10c, 10d, 10e, and 10f may be used not only for installation on the battery 1, but also for placement between circuit boards, between electronic components, or between circuit boards and electronic components in electronic devices.

[0073] The fire-spread prevention sheet 10 is a sheet that can be interposed between heat sources to prevent the spread of fire between them, and has a laminate structure in which a metal film 13 is sandwiched between a first rubber sheet 11 and a second rubber sheet 12, and the metal film 13 is a film in which metal particles 15 are deposited. At least one of the first rubber sheet 11 and the second rubber sheet 12 is preferably a sponge-like porous sheet. At least one of the first rubber sheet 11 and the second rubber sheet 12 is preferably silicone rubber. The metal film 13 may be formed on at least one side in the thickness direction of the second rubber sheet 12. The metal film 13 of the first rubber sheet 11 and the metal film 13 of the second rubber sheet 12 may be facing each other. An adhesive layer, a heat insulating sheet 31, 32 may be placed between the metal films 13.

[0074] A method for manufacturing a fire-spread prevention sheet may include a metal film forming step of forming a metal film 13 on one side in the thickness direction of a first rubber sheet 11, and a lamination step of laminating a second rubber sheet 12 onto the metal film 13 surface of the first rubber sheet 11. Prior to the metal film forming step, a primer treatment step may be performed on one side in the thickness direction of the first rubber sheet 11 to facilitate the formation of the metal film 13. The metal film forming step may also be performed by metal vapor deposition or sputtering.

[0075] Battery 1 is comprised of multiple battery cells 5 arranged in a row, with one of the aforementioned fire-spread prevention sheets 1 interposed at least between the battery cells 5.

[0076] The metal film 13 may be formed on at least one side in the thickness direction of the second rubber sheet 12, and also on the surface of the first rubber sheet 11 facing the metal film 13. The second rubber sheet 12 is preferably a sponge-like porous sheet. It is preferable that the metal film 13 is formed so as to penetrate both the surfaces of the porous sheet other than the holes and into the holes.

[0077] The components or processes of each of the above embodiments can be combined in any way, except where they are incompatible. In particular, each claim can be combined in any way. [Examples]

[0078] Next, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments.

[0079] 1. Manufacturing of fire-resistant sheets Figure 12 shows schematic diagrams of the layer structure of the foamed silicone rubber sheets of Examples 1 and 2 and Comparative Examples 1 and 2.

[0080] (Example 1) (1) Manufacturing of foamed silicone rubber sheets The foamed silicone rubber sheets, which served as the first and second rubber sheets, were manufactured under the following conditions. First, 100 parts by mass of a curable silicone rubber composition (product code: KE-9710U, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.3 parts by mass of an organic peroxide crosslinking agent (product code: C-1A, manufactured by Shin-Etsu Chemical Co., Ltd.), 2.0 parts by mass of an organic peroxide crosslinking agent (product code: C-3, manufactured by Shin-Etsu Chemical Co., Ltd.), and 2.0 parts by mass of an addition-reaction type crosslinking agent (product code: C-25A, manufactured by Shin-Etsu Chemical Co., Ltd.) were prepared. 1.0 part by mass of a foaming agent and 1.0 part by mass of a coloring agent were added to these, and the mixture was kneaded using a mixing roll. Here, 1 part by mass corresponds to 1 g. The same applies to the following examples. While the kneaded mixture was dispensed into a sheet using a mixing roll, a polyethylene terephthalate (PET) film was attached to one side of the sheet-like molded product. Next, the dispensed sheet-like molded product was peeled off the mixing roll, and the PET film was attached to the other side as well. The sheet-like molded material was placed in a constant temperature bath heated to 195°C and subjected to primary vulcanization for 5 minutes. After that, the sheet-like molded material was removed from the constant temperature bath, the PET film attached to both sides was peeled off, and secondary vulcanization was performed at 200°C for 4 hours to produce a foamed silicone rubber sheet with a thickness of approximately 2.1 mm. Next, this sheet was cut into rectangular sheets with dimensions of 100 mm in width and 300 mm in length in a plan view. (2) Formation of aluminum film Next, a thin aluminum film was formed on one side of a foamed silicone rubber sheet. The thin film was formed under the following conditions: The aluminum film was formed by sputtering. The foamed silicone rubber (referred to as the substrate) was placed in the vacuum chamber of a carousel-type batch sputtering apparatus (method: DC magnetron sputtering). Pure aluminum was used as the sputtering target. The vacuum level inside the vacuum chamber was set to approximately 5 × 10⁻⁶. ―4 After setting to Pa, the substrate temperature was 25°C, sputtering power was 9kW, Ar flow rate was 650 sccm, and deposition pressure was 3 × 10⁻¹⁰. ―1 Sputtering was performed under Pa conditions. After 10 minutes of sputtering, an aluminum film with a thickness of approximately 100 nm was formed on one side of the substrate. The film thickness was measured using a Bruker stylus-type step gauge (model: DXT-E). (3) Manufacturing of laminates Two foamed silicone rubber sheets, one with a thin aluminum film and the other with a foamed silicone rubber film, were bonded together using an adhesive (Cemedine Co., Ltd., product number: SuperX) with the thin aluminum film facing inward. Next, a heat insulating sheet containing talc, silica, and aerogel (Awa Paper Co., Ltd., product number: I-80F, thickness 0.8~1.0 mm) was bonded to both outer surfaces of the laminate using the same adhesive. As a result, a fire-resistant sheet consisting of a heat insulating sheet / foamed silicone rubber sheet / aluminum film / foamed silicone rubber sheet / heat insulating sheet was completed. The total thickness of the fire-resistant sheet was approximately 6.8 mm. The sample manufactured under the conditions of Example 1 is designated as "A".

[0081] (Example 2) The manufacturing of the foamed silicone rubber sheet and the formation of the aluminum film were carried out in the same manner as in Example 1. In the manufacturing of the laminate, unlike in Example 1, an insulating sheet (manufactured by Awa Paper Co., Ltd., product number: I-80F, thickness 0.8~1.0 mm) was bonded to both sides of the foamed silicone rubber sheet with the aluminum thin film using an adhesive (manufactured by Cemedyne Co., Ltd., product number: SuperX). As a result, a fire-resistant sheet consisting of an insulating sheet / foamed silicone rubber sheet / aluminum thin film / insulating sheet was completed. The total thickness of the fire-resistant sheet was approximately 4.5 mm. The sample manufactured under the conditions of Example 2 is designated as "B".

[0082] (Comparative Example 1) A foamed silicone rubber sheet was prepared using the same formulation as in Example 1, but with the thickness increased from 2.1 mm to 4.2 mm. The cut size was the same as in Example 1. Unlike Example 1, the laminate was manufactured by bonding an insulating sheet (manufactured by Awa Paper Co., Ltd., product number: I-80F, thickness 0.8~1.0 mm) to both sides of the foamed silicone rubber sheet using an adhesive (manufactured by Cemedyne Co., Ltd., product number: SuperX). As a result, an insulating sheet / foamed silicone rubber sheet / insulating sheet fire prevention sheet was completed. The total thickness of the fire prevention sheet was approximately 6.6 mm. The fire prevention sheet of Comparative Example 1 has a layer structure that is the same as the fire prevention sheet of Example 1 but without the thin aluminum film. The sample manufactured under the conditions of Comparative Example 1 is designated as "C".

[0083] (Comparative Example 2) The foamed silicone rubber sheet was manufactured under the same conditions as in Example 1. A laminate was created by sandwiching an aluminum foil (manufactured by Toyo Aluminum Co., Ltd., thickness: approximately 11 μm) between two foamed silicone rubber sheets using the adhesive used in Example 1. Next, the heat insulating sheet used in Example 1 was bonded to both outer surfaces of the laminate using the same adhesive. As a result, a fire-resistant sheet consisting of a heat insulating sheet / foamed silicone rubber sheet / aluminum foil / foamed silicone rubber sheet / heat insulating sheet was completed. The total thickness of the fire-resistant sheet was approximately 6.8 mm. The sample manufactured under the conditions of Comparative Example 2 is designated as "D".

[0084] 2. Evaluation of the characteristics of fire-spread prevention sheets (1) Experiment 1 (Evaluation of thermal resistance and thermal conductivity) Figure 13 shows a photograph of a thermal resistance measuring apparatus used to investigate the thermal resistance and thermal conductivity of three samples from Examples 1 and 2 and Comparative Example 1. Figure 14 shows a photograph of each sample A, B, and C sandwiched between the upper rod (also called the reference material) and the lower rod (also called the reference material). Figure 15 shows a schematic diagram of the sample sandwiched between the upper and lower rods. (15A) shows the heat flow from the heat source to the upper rod, sample, lower rod, and heat sink (cooling section), the compression of the sample between the upper and lower rods, and the locations where the four thermocouples are fixed. (15B) shows the thermal resistance (R) of the sample itself.th,Bulk ), the thermal resistance between the sample and the upper rod (R th,contact Ref-sample ), the thermal resistance between the sample and the lower rod (R th,contact Ref-sample ), and show the measurement formula for thermal conductivity.

[0085] The thermal resistance measurement apparatus of FIG. 13 (a TIM tester manufactured by ZFW Co., Ltd.) is equipped with a system that supplies heat from the upper rod to heat the sample, and is further equipped with a unit capable of compressing the sample using hydraulic pressure and an apparatus that optically measures the thickness of the sample (denoted as dx or Gap). The end face area (Area) of the upper rod and the lower rod is 706.86 mm 2 . The thermal resistance measurement apparatus of FIG. 13 is an apparatus that measures thermal resistance and thermal conductivity based on "ASTM D5470-17", which is a standard for evaluating thermal resistance and thermal conductivity. The thermal resistance of the sample itself (R th,Bulk ), the thermal resistance between the sample and the upper rod (R th,contact Ref-sample ), and the thermal resistance between the sample and the lower rod (R th,contact Ref-sample ), a total of three thermal resistances, are denoted as R th,app . As shown in FIG. 15 (15B), the thermal resistance measurement apparatus of FIG. 13 measures R, which is the sum of the three thermal resistances th,app , and can determine the thermal conductivity (λ th,app ) by calculating dx / Area·R eff or λ app ).

[0086] Table 1, Table 2 and Table 3 show the output data when Sample A of Example 1, Sample B of Example 2 and Sample C of Comparative Example 1 were measured by the thermal resistance measurement apparatus of FIG. 13. In the tables, Gap denotes the thickness when the sample is compressed, Force denotes the load applied to compress the sample, R th,app denotes the thermal resistance (as described above), λ app denotes the thermal conductivity, R th,app ·A denotes the value obtained by multiplying R th,app by the area, Pressure denotes the pressure resulting from the load applied to the sample, T sample denotes the temperature of the sample, and Q bottom denotes the heat flow through the sample, respectively.

[0087] Figure 16 shows the changes in thermal resistance (16A) and thermal conductivity (16B) when the pressure applied to sample A of Example 1, sample B of Example 2, and sample C of Comparative Example 1 is increased.

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3]

[0091] As shown in Tables 1-3 and Figure 16, a common trend observed in all samples was that as the pressure on the sample increased, its thickness decreased, its thermal resistance decreased, and its thermal conductivity increased. However, samples A and B (Examples 1 and 2) showed a significantly smaller decrease in thermal resistance and a smaller increase in thermal conductivity compared to sample C (Comparative Example 1). This result indicates that forming a thin aluminum film inside the fire-prevention sheet allows for higher thermal resistance even when the pressure is increased, compared to sheets without the thin film, and consequently, lower thermal conductivity. Therefore, it is considered that the thin aluminum film can suppress heat transfer from one side of the fire-prevention sheet to the other.

[0092] (2) Experiment 2 (Evaluation of stress and strain) Figure 17 shows a graph of the relationship between thickness and stress when Sample A from Example 1, Sample C from Comparative Example 1, and Sample D from Comparative Example 2 are compressed in the thickness direction. The horizontal axis of the graph represents thickness (mm), and the vertical axis represents stress (MPa). "Stress Strain" in the graph refers to stress strain. The apparatus used in Experiment 1 (see Figure 13) was used for this evaluation.

[0093] As shown in Figure 17, a common trend was observed in all samples: stress tended to increase with decreasing sample thickness. However, samples A and C exhibited lower stress levels when compressed in the thickness direction compared to sample D. Sample C has a structure in which a foamed silicone rubber sheet is sandwiched between insulating sheets. Sample A has the same structure as sample C, plus a thin aluminum film sandwiched inside the foamed silicone rubber sheet. Sample D has aluminum foil instead of the thin aluminum film found in sample C. From these results, it was found that even with a thin aluminum film inside the fire-prevention sheet, it exhibited low stress-strain characteristics equivalent to those of a fire-prevention sheet without the film. On the other hand, it was found that the stress-strain increased when aluminum foil was added to the fire-prevention sheet. This result indicates that aluminum foil hinders the low stress-strain characteristics of the foamed silicone rubber sheet, but the thin aluminum film does not hinder the low stress-strain characteristics of the foamed silicone rubber sheet.

[0094] 3. Evaluation of aluminum thin films and aluminum foils within fire-spread prevention sheets. (1) Evaluation of electrical conductivity To investigate the cause of the results in Experiment 2, the electrical conductivity of two sheets were investigated: one made of foamed silicone rubber with a thin aluminum film formed on one side (sheet a), which constitutes sample A; and the other made of foamed silicone rubber with aluminum foil attached to one side (sheet d), which constitutes sample D. The electrical conductivity of sheet d was investigated using a four-terminal resistance meter (model: MCP-T600) manufactured by Mitsubishi Chemical Corporation. As a result, sheet d showed extremely high electrical conductivity (electrical resistance value: 0.0024 Ω / □). On the other hand, the electrical conductivity of sheet a was investigated using a Highresta (model: MCP-HT450) manufactured by Mitsubishi Chemical Analytec. As a result, it was found that sheet a hardly conducts electricity at all (electrical resistance value: Overload, meaning the electrical resistance value is infinite).

[0095] (2) Observation of microtissue Figure 18 shows an optical microscope image (magnification at observation: 500x) of the aluminum thin film of sheet a, which constitutes sample A. Figure 19 shows scanning electron microscope images (magnification at observation: 1000x, 3000x, and 10000x) of the aluminum thin film of sheet a.

[0096] Observation of the thin film using an optical microscope and a scanning electron microscope revealed that the thin film contained numerous fine cracks and was composed of many small scales rather than a single film. In other words, while aluminum foil exists as a single sheet, the aluminum thin film consists of multiple small pieces. This difference in morphology is thought to be related to the phenomenon that aluminum foil hinders the low stress-strain properties of the foamed silicone rubber sheet, while the aluminum thin film does not. Furthermore, this difference in morphology is also thought to be related to the phenomenon that aluminum foil had excellent electrical conductivity, while the aluminum thin film conducted almost no electricity. [Industrial applicability]

[0097] This invention can be used, for example, in automobile batteries.

Claims

1. A fire-spread prevention sheet that can be interposed between heat sources to prevent the spread of fire between them, It has a laminate structure with multiple layers, The first rubber sheet is provided with a metal film attached to its interior in the thickness direction of the fire-spread prevention sheet, with a metal film on at least one side in the thickness direction of the first rubber sheet. The aforementioned metal film is a film in which metal particles are deposited, The metal film is formed at least 1 mm inward from both surfaces in the thickness direction of the fire-spread prevention sheet. A fire-spread prevention sheet characterized by having a metal oxide-containing heat insulating sheet on the metal film side of the rubber sheet with a metal film.

2. A fire-spread prevention sheet that can be interposed between heat sources to prevent the spread of fire between them, It has a laminate structure with multiple layers, The first rubber sheet is provided with a metal film attached to its interior in the thickness direction of the fire-spread prevention sheet, with a metal film on at least one side in the thickness direction of the first rubber sheet. The aforementioned metal film is a film in which metal particles are deposited, The metal film side of the rubber sheet with the metal film is provided with a heat insulating sheet containing a metal oxide. A fire-spread prevention sheet characterized by having the outside of the aforementioned multiple layers covered with an insulating film.

3. A fire-spread prevention sheet that can be interposed between heat sources to prevent the spread of fire between them, It has a laminate structure with multiple layers, The first rubber sheet is provided with a metal film attached to its interior in the thickness direction of the fire-spread prevention sheet, with a metal film on at least one side in the thickness direction of the first rubber sheet. The aforementioned metal film is a film in which metal particles are deposited, The fire-preventing sheet is provided with a metal oxide-containing heat-insulating sheet on at least one outer side in the thickness direction, The fire-spread prevention sheet is characterized in that the metal film is formed at least 1 mm inward from both surfaces in the thickness direction of the fire-spread prevention sheet.

4. A fire-spread prevention sheet that can be interposed between heat sources to prevent the spread of fire between them, It has a laminate structure with multiple layers, The first rubber sheet is provided with a metal film attached to its interior in the thickness direction of the fire-spread prevention sheet, with a metal film on at least one side in the thickness direction of the first rubber sheet. The aforementioned metal film is a film in which metal particles are deposited, The fire-preventing sheet is provided with a metal oxide-containing heat-insulating sheet on at least one outer side in the thickness direction, A fire-spread prevention sheet characterized by having the outside of the aforementioned multiple layers covered with an insulating film.

5. The fire-spread prevention sheet according to any one of claims 1 to 4, characterized in that the first rubber sheet is a sponge-like porous sheet.

6. The aforementioned plurality of layers further comprises a second rubber sheet, The fire-spread prevention sheet according to any one of claims 1 to 4, characterized in that the second rubber sheet is arranged opposite to the surface of the metal-filmed rubber sheet that has the metal film.

7. The fire-spread prevention sheet according to claim 6, characterized in that at least one of the first rubber sheet and the second rubber sheet is a sponge-like porous sheet.

8. The fire-spread prevention sheet according to any one of claims 1 to 4, characterized in that the metal film is a thin film mainly composed of aluminum, copper, tin, silver, or gold, or a thin film of an alloy containing at least one of the elements aluminum, copper, tin, silver, or gold.

9. The fire-spread prevention sheet according to claim 1 or 2, characterized in that the heat-insulating sheet is provided with a second rubber sheet on the side opposite to the metal film.

10. A method for manufacturing a fire-spread prevention sheet that can be interposed between heat sources to prevent the spread of fire between them, The aforementioned fire-spread prevention sheet has a laminate structure having multiple layers. A metal film forming step to produce a rubber sheet with a metal film by forming a metal film in which metal particles are deposited on at least one side in the thickness direction of a first rubber sheet, which is one of the plurality of layers, The process includes a lamination step of laminating the first rubber sheet with one or two other layers, One or two of the aforementioned layers include a metal oxide-containing insulating sheet. A method for manufacturing a fire-spread prevention sheet, characterized in that, after the lamination step, a coating step is performed in which the outside of the plurality of layers is covered with an insulating film.

11. The method for manufacturing a fire-preventing sheet according to claim 10, characterized in that one or two of the other layers include a second rubber sheet.

12. The method for manufacturing a fire-spread prevention sheet according to claim 10 or 11, characterized in that the metal film formation step is carried out by a metal deposition or sputtering process.

13. The method for manufacturing a fire-spread prevention sheet according to claim 10 or 11, characterized in that, prior to the metal film formation step, a primer treatment step is performed on one side of the first rubber sheet in the thickness direction to facilitate the formation of the metal film.

14. A battery that has multiple battery cells arranged in a row, A battery characterized in that a fire-spread prevention sheet according to any one of claims 1 to 4 is interposed between the battery cells that serve as heat sources.

Images