Fire spread prevention sheet, method of manufacturing the same, and battery including the same

Abstract

To provide a heat extension prevention sheet having low thermal conductivity and high cushioning properties, a method of manufacturing the same, and a battery including the same.SOLUTION: Provided is a fire spread prevention sheet 1 that includes a heat insulating sheet 3 containing a metal oxide capable of inhibiting heat transfer from a heat source and a rubber sheet 2 having higher elasticity than the heat insulating sheet 3, wherein some sheet end faces 3a, 3b of the heat insulating sheet 3 are exposed from the outer periphery of the rubber sheet 2; ventilation flow paths 4, 5 are provided between the heat insulating sheet 3 and the inside of the rubber sheet 2, allowing ventilation to the outside; the flow paths 4, 5 are formed along the outer surface of the heat insulating sheet 3 from first openings 4a, 5a opened to the side of a first sheet end face 3a included in some of the sheet end faces; and lead to second openings 4b, 5b opening to the side of a second sheet end face 3b, another sheet end face included in some of the sheet end faces. Also described are a method of manufacturing the same, and a battery including the same.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire prevention sheet, a method for manufacturing the same, and a battery including the same. [Background technology]

[0002] Currently, there is a growing movement around the world to gradually replace conventional gasoline or diesel vehicles with electric vehicles in order to reduce the burden on the global environment. Electric vehicles are becoming increasingly popular, particularly in European countries such as France, the Netherlands, and Germany, as well as in China. The widespread use of electric vehicles requires high-performance batteries.

[0003] Some batteries may experience thermal runaway during discharge or charging, resulting in fire, smoke, or other problems. Recently, automotive batteries with multiple battery cells arranged in a housing have become known. In such a battery with multiple battery cells arranged in a row, if one battery cell were to catch fire or emit smoke, the heat could be transferred to the surrounding battery cells, potentially causing further fires, smoke, explosions, or other problems. To minimize damage caused by such problems, methods have been developed to prevent the transfer of heat from abnormally hot battery cells to the surrounding battery cells. For example, a known method involves providing a fire-prevention sheet, such as a fire-resistant material or a heat-insulating layer, between multiple battery cells (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-206604 Summary of the Invention [Problem to be solved by the invention]

[0005] As a fire prevention sheet, for example, a ceramic fire-resistant sheet can be placed between battery cells (also simply referred to as "cells"). However, the cell containers that make up a battery expand when overheated during discharge and / or charging. Therefore, even though high-hardness ceramic sheets have low thermal conductivity and excellent heat resistance, they are not suitable for preventing fire spread between cells because they have poor cushioning properties. On the other hand, even though resin sheets have slightly better cushioning properties than ceramic sheets, they are inferior to ceramic sheets in terms of heat resistance.

[0006] There is a market demand for a heat spread prevention sheet that has low thermal conductivity in the thickness direction and excellent cushioning in the same direction. Meeting this demand will also contribute to the achievement of the Applicant's Sustainable Development Goal of "ensuring access to affordable, reliable, sustainable and modern energy for all."

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a heat spread prevention sheet having low thermal conductivity and high cushioning properties, a method for manufacturing the same, and a battery equipped with the same. [Means for solving the problem]

[0008] (1) In order to achieve the above object, one embodiment of a fire spread prevention sheet is a fire spread prevention sheet that is disposed at least between a plurality of heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, a heat insulating sheet capable of suppressing heat transfer from the heat source and containing a metal oxide; a rubber sheet having higher elasticity than the heat insulating sheet; Equipped with a part of the sheet end surface of the heat insulating sheet is exposed from the outer periphery of the rubber sheet; a ventilation flow path that allows ventilation between the heat insulating sheet and the inside of the rubber sheet, The flow path extends from a first opening that opens to the side of a first sheet end face included in the portion of the sheet end faces to a second opening that is formed along the outer surface of the insulation sheet and opens to the side of a second sheet end face, which is another sheet end face included in the portion of the sheet end faces. (2) In another embodiment of the fire spread prevention sheet, preferably, the first sheet end face and the second sheet end face are opposite each other, and two flow paths may be formed from the first sheet end face to the second sheet end face. (3) In order to achieve the above object, a fire spread prevention sheet according to one embodiment is a fire spread prevention sheet that is disposed at least between a plurality of heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, a heat insulating sheet capable of suppressing heat transfer from the heat source and containing a metal oxide; a rubber sheet having higher elasticity than the heat insulating sheet; Equipped with a part of the sheet end surface of the heat insulating sheet is exposed from the outer periphery of the rubber sheet; a ventilation flow path that allows ventilation between the heat insulating sheet and the inside of the rubber sheet, The flow path extends from a first opening that opens to the side of a first sheet end face included in the portion of the sheet end face to a second opening that is formed along the outer surface of the insulation sheet and is different from the first opening and opens to the side of the first sheet end face. (4) In another embodiment of the fire spread prevention sheet, preferably, the sheet surface of the rubber sheet that covers one side of the thickness direction of the insulating sheet may be raised in the thickness direction of the rubber sheet compared to the sheet surface that covers the other side of the thickness direction. (5) In another embodiment of the fire spread prevention sheet, preferably, the sheet surface covering one side of the thickness direction of the insulating sheet may have a step that reduces the thickness of the rubber sheet above the flow path between the center of the surface of the insulating sheet, passing above the flow path, and reaching the end. (6) In the fire spread prevention sheet according to another embodiment, the rubber sheet may preferably be a porous rubber sheet. (7) In the fire prevention sheet according to another embodiment, the heat insulating sheet may preferably contain at least one of silica, diatomaceous earth, and talc as the metal oxide or material containing the metal oxide. (8) In order to achieve the above object, one embodiment of a method for manufacturing a fire spread prevention sheet is a method for manufacturing a fire spread prevention sheet that is disposed at least between a plurality of heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, The fire spread prevention sheet is a heat insulating sheet capable of suppressing heat transfer from the heat source and containing a metal oxide; a rubber sheet having higher elasticity than the heat insulating sheet; Equipped with a part of the sheet end surface of the heat insulating sheet is exposed from the outer periphery of the rubber sheet; a ventilation flow path that allows ventilation between the heat insulating sheet and the inside of the rubber sheet, the flow path leads from a first opening that opens to a side of a first sheet end face included in the partial sheet end faces to a second opening that is formed along the outer surface of the heat insulating sheet and opens to a side of a second sheet end face that is another sheet end face included in the partial sheet end faces, or leads from the first opening to a second opening that is formed along the outer surface of the heat insulating sheet and is different from the first opening and opens to a side of the first sheet end face, The method for producing the fire spread prevention sheet includes: a placement step of placing the heat insulating sheet on a first curable rubber sheet; a covering step of covering the heat insulating sheet with a second curable rubber sheet after the placing step; a lamination step of sandwiching the heat insulating sheet between the first curable rubber sheet and the second curable rubber sheet and laminating the first curable rubber sheet and the second curable rubber sheet together so as to form the flow path; a curing step of curing at least the first curable rubber sheet and the second curable rubber sheet to integrate the first curable rubber sheet, the heat insulating sheet, and the second curable rubber sheet; Includes. (9) In another embodiment of the method for manufacturing a fire prevention sheet, the laminating step may preferably be a step of performing laminating processing by applying a roller to the sheet surface covering one side of the thickness direction of the insulating sheet in a direction from the center of the surface of the insulating sheet, past a position above the flow path, to the end. (10) In another embodiment of the method for producing a fire spread prevention sheet, preferably, when the flow paths are present at two locations in the width direction of the heat insulating sheet, The lamination process may be a process of performing a lamination process by applying the roller to the sheet surface covering one side of the thickness direction of the insulation sheet in a direction from the center of the surface of the insulation sheet, past a position above the flow path, to both ends in the width direction. (11) In another embodiment of the method for producing a fire spread prevention sheet, preferably, when the flow paths are present in two locations in the width direction and one location in the length direction of the heat insulating sheet, The lamination process may further be a process of performing a lamination process by applying the roller to the sheet surface covering one side of the thickness direction of the insulation sheet in a direction from the center of the surface of the insulation sheet, past a position above the flow path, to one end in the longitudinal direction. (12) In another embodiment of the method for manufacturing a fire prevention sheet, it is preferable that the method further includes a cutting step of cutting the hardened body after the hardening step so as to remove the flow path on the longitudinal side of the insulating sheet. (13) In order to achieve the above object, a battery according to one embodiment comprises: A battery including a plurality of battery cells in a housing, Any of the fire spread prevention sheets described above is provided at least between the battery cells, among between the battery cells and between the battery cells and the housing. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a heat spread prevention sheet having low thermal conductivity and high cushioning properties, a method for manufacturing the same, and a battery including the same. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows a plan view, a front view, and a right side view of a fire spread prevention sheet according to a first embodiment. [Figure 2] FIG. 2 shows a cross-sectional view of the fire spread prevention sheet of FIG. 1 taken along line AA, a cross-sectional view of the same sheet taken along line BB, and an enlarged view of part C in the cross-sectional view taken along line AA. [Figure 3] FIG. 3 shows a plan view, a front view, and a right side view of the fire spread prevention sheet according to the second embodiment. [Figure 4] FIG. 4 shows a cross-sectional view of the fire spread prevention sheet of FIG. 3 taken along line DD and a cross-sectional view of the same sheet taken along line EE. [Figure 5] FIG. 5 shows a flow of the main steps for manufacturing a fire spread prevention sheet according to one embodiment. [Figure 6] FIG. 6 shows a diagram for explaining the steps from the covering step to the laminating step (6A) and the cutting step (6B) in the flow of FIG. [Figure 7] FIG. 7 shows a longitudinal cross-sectional view of a battery according to one embodiment and an enlarged view of one fire spread prevention sheet sandwiched between battery cells in the longitudinal cross-sectional view. [Figure 8] Figure 8 is a diagram for explaining the method of evaluating the thermal conductivity of a fire spread prevention sheet according to the second embodiment, showing an oblique view (8A) of an area 20 mm from the end of the long side of the fire spread prevention sheet and a cross-sectional view (8B) of the vicinity of the same area during evaluation. [Figure 9] Figure 9 shows the temperature distribution of comparative material 1 (labeled "SR sponge" in the figure), comparative material 2 (labeled "SR sponge + insulation sheet" in the figure), and fire prevention sheet 1a (labeled "SR sponge + insulation sheet + cavity" in the figure) just before the start of the evaluation (initial stage). [Figure 10]FIG. 10 shows the temperature distribution of each evaluation object 60 seconds after the initial state of FIG. [Figure 11] FIG. 11 shows the temperature distribution of each evaluation object 120 seconds after the initial state of FIG. [Figure 12] FIG. 12 shows the temperature distribution of each evaluation object 180 seconds after the initial state of FIG. [Figure 13] FIG. 13 shows the temperature distribution of each evaluation object 240 seconds after the initial state of FIG. [Figure 14] FIG. 14 shows the temperature distribution of each evaluation object 300 seconds after the initial state of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, various embodiments of the present invention will be described with reference to the drawings. Note that the various embodiments described below do not limit the scope of the invention as claimed, and not all of the elements and combinations thereof described in the various embodiments are necessarily essential to the solution of the present invention.

[0012] 1. Fire prevention sheet (1) First embodiment Fig. 1 shows a plan view, a front view, and a right side view of the fire spread prevention sheet according to the first embodiment. Fig. 2 shows a cross-sectional view of the fire spread prevention sheet of Fig. 1 taken along line AA, a cross-sectional view of the same sheet taken along line BB, and an enlarged view of part C in the cross-sectional view of line AA.

[0013] The fire spread prevention sheet 1 according to this embodiment is a sheet that is placed at least between multiple heat sources and can prevent the spread of fire by suppressing heat transfer to other heat sources when a heat source is overheated. Here, examples of "heat sources" include battery cells placed inside an automobile battery, batteries used for devices other than automobiles, or battery cells placed inside such batteries. However, "heat sources" also include, in addition to batteries or battery cells, heaters or their components, and components in electrical or electronic devices (circuit boards, circuit components, etc.).

[0014] The fire spread prevention sheet 1 includes a heat insulating sheet 3 capable of suppressing heat transfer from a heat source and a rubber sheet 2 having greater elasticity than the heat insulating sheet 3. Some sheet end faces 3a, 3b of the heat insulating sheet 3 are exposed from the outer periphery of the rubber sheet 2. In this embodiment, the sheet end faces 3a, 3b are the two end faces on the shorter sides of the heat insulating sheet 3, which is rectangular in plan view and smaller in thickness direction, i.e., both longitudinal end faces of the heat insulating sheet 3. The fire spread prevention sheet 1 includes ventilation flow paths 4, 5 between the heat insulating sheet 3 and the inside of the rubber sheet 2, allowing ventilation to the outside. Note that the "flow path" is also referred to as a channel. The flow paths 4, 5 extend from first openings 4a, 5a opening laterally to a first sheet end face 3a included in the aforementioned partial sheet end faces 3a, 3b, to second openings 4b, 5b formed along the outer surface of the heat insulating sheet 3 and opening laterally to a second sheet end face 3b, another sheet end face included in the aforementioned partial sheet end faces 3a, 3b.

[0015] In this embodiment, the first sheet end face 3a and the second sheet end face 3b are opposite end faces. Two flow paths 4 and 5 are formed, connecting the first sheet end face 3a to the second sheet end face 3b. More specifically, the flow path 4 is a substantially linear air passage extending from a first opening 4a located on the side of the first sheet end face 3a along the long side of the cross-sectional sheet 3 to a second opening 4b located on the side of the second sheet end face 3b. The flow path 5 is a substantially linear air passage extending from a first opening 5a located on the side of the first sheet end face 3a along the long side of the cross-sectional sheet 3 to a second opening 5b located on the side of the second sheet end face 3b. The first opening 5a is located on the opposite side of the first opening 4a across the first sheet end face 3a. The second opening 5b is located on the opposite side of the second sheet end face 3b across the second sheet end face 3b. As a result, the heat insulating sheet 3 is in close contact with the rubber sheet 2 on both sides thereof that are widest in the thickness direction, while the entire outer peripheral edge surface is exposed to the air.

[0016] In the fire spread prevention sheet 1, the sheet surface of the rubber sheet 2 on one side covering the heat insulating sheet 3 in the thickness direction is preferably raised in the thickness direction of the rubber sheet compared to the sheet surface on the other side covering the heat insulating sheet 3 in the thickness direction. In this embodiment, as shown in the front view of FIG. 1 , the bottom surface of the rubber sheet 2 located below the heat insulating sheet 3 is substantially flat, while the top surface of the rubber sheet 2 located above the heat insulating sheet 3 has a gently raised shape. In addition, the sheet surface on the side covering one side in the thickness direction of the heat insulating sheet 3 (i.e., the top surface) may have a step that reduces the thickness of the rubber sheet 2 above the flow channels 4 and 5, from the center of the surface of the heat insulating sheet 3, past the position above the flow channels 4 and 5, to the end of the fire spread prevention sheet 1. This step will be described in detail in the explanation of the manufacturing method.

[0017] In this embodiment, the rubber sheet 2 is preferably a porous rubber sheet (also called a foam rubber sheet). As described above, the heat insulating sheet 3 has both of its widest surfaces fixed to the inner surface of the rubber sheet 2. Therefore, even if a portion of the widest surface of the heat insulating sheet 3 chips or becomes powdery, the chipped portion or powder is unlikely to spill out of the fire spread prevention sheet 1. The rubber sheet 2 is a porous elastic sheet and contains numerous pores. The rubber sheet 2 functions as a cushioning member that can compress and expand in response to the thermal expansion and subsequent contraction of battery cells, which are an example of a heat source. Furthermore, the pores present inside and on the surface of the rubber sheet 2 provide space for air storage when a heat source is present on both sides of the rubber sheet 2 in the thickness direction, or when a heat source and a non-heat source are present on both sides. Therefore, the rubber sheet 2 contributes to the high thermal insulation properties of the fire spread prevention sheet 1.

[0018] The ratio of the volume of the holes (also called "voids") in the rubber sheet 2 to the volume of the rubber sheet 2 (the external volume including the holes) is preferably 50 / 100 to 95 / 100, and more preferably 60 / 100 to 85 / 100. The holes contribute to the function of increasing the heat insulating properties of the rubber sheet 2, and also contribute to the function of facilitating elastic deformation of the rubber sheet 2 when compressed and released.

[0019] The rubber sheet 2 is made of an elastomer to provide elastic deformation properties to the rubber sheet 2. The rubber sheet 2 is preferably obtained through a foaming and curing process using heat. Therefore, the elastomer is preferably a thermosetting elastomer. Examples of thermosetting elastomers include silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, ethylene propylene diene rubber, nitrile rubber (NBR), and styrene butadiene rubber (SBR). Among these, silicone rubber, which has relatively high heat resistance, is preferred. The rubber sheet 2 is more preferably a foamed silicone rubber sheet.

[0020] The heat insulating sheet 3 is a sheet containing a metal oxide and preferably has higher heat resistance than the rubber sheet 2. By enclosing the heat insulating sheet 3 within the fire prevention sheet 1, even if a battery cell overheats and, in the worst case, catches fire, heat transfer to other battery cells adjacent to the battery cell in question can be prevented. The heat insulating sheet 3 may be a sheet containing only a metal oxide, but is preferably a composite sheet containing a metal oxide and resin or rubber. As described below, the heat insulating sheet 3 preferably contains, as the metal oxide or material containing the metal oxide, silica, aerogel (including silica aerogel), diatomaceous earth, talc, mica, aluminum hydroxide, and / or magnesium hydroxide, and more preferably, as the metal oxide or material containing the metal oxide, at least one of silica, diatomaceous earth, and talc. The heat insulating sheet 3 can be obtained, for example, by a manufacturing method including a mold forming process or a process similar to papermaking. In this embodiment, the heat insulating sheet 3 does not have holes like the rubber sheet 2. However, the heat insulating sheet 3 may have holes.

[0021] When the heat insulating sheet 3 contains a resin, the resin is preferably polyphenylene sulfide (PPS) or polyether ether ketone (PEEK), which have excellent heat resistance. When the heat insulating sheet 3 contains a rubber, the rubber is preferably a thermosetting elastomer such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, ethylene propylene diene rubber, nitrile rubber (NBR), or styrene butadiene rubber (SBR).

[0022] When the heat insulating sheet 3 contains a metal oxide but no resin or rubber, the mass ratio of the metal oxide in the heat insulating sheet 3 is preferably 80 to 100 mass%, more preferably 85 to 99 mass%. When the heat insulating sheet 3 contains a resin or rubber in addition to the metal oxide, the mass ratio of the metal oxide in the heat insulating sheet 3 is preferably 50 to 80 mass%, more preferably 60 to 75 mass%. That is, the heat insulating sheet 3 preferably contains at least one of silica, diatomaceous earth, and talc in an amount of 50 mass% or more relative to the total mass of the heat insulating sheet 3. The filler may also be surface-treated. For example, a silane coupling agent can be used to surface treat the filler.

[0023] The total thickness of the fire spread prevention sheet 1 is not particularly limited. It can be selected appropriately depending on the type and size of the heat source, the size of the space in which the fire spread prevention sheet 1 is placed, and the number of fire spread prevention sheets 1 to be used. For example, if the heat source is a battery cell for an automobile, which is subject to large vibrations, the rubber sheet 2, which acts as a cushion, may be made thicker. If the heat source is a heater or a component in an electronic device, which is not subject to large vibrations, the heat insulating sheet 3 may be made thicker.

[0024] Considering the productivity and versatility of the fire spread prevention sheet 1, the total thickness of the fire spread prevention sheet 1 is preferably 0.8 to 10 mm, and more preferably 1.5 to 5 mm. In this case, the thickness of the rubber sheet 2 on one side of the heat insulating sheet 3 in the thickness direction can be set to a range of 0.3 to 2 mm, and the thickness of the heat insulating sheet 3 can be set to a range of 0.5 to 2 mm.

[0025] The flow paths 4 and 5 function to release heat transmitted to the fire spread prevention sheet 1 to the outside. The flow paths 4 and 5 act as channels for air flow, particularly when the fire spread prevention sheet 1 is compressed in the thickness direction. Therefore, the fire spread prevention sheet 1 equipped with the flow paths 4 and 5 can effectively suppress heat transfer from one side of the sheet 1 to the other side in the thickness direction.

[0026] (2) Second embodiment Fig. 3 shows a plan view, a front view, and a right side view of a fire spread prevention sheet according to a second embodiment. Fig. 4 shows a cross-sectional view of the fire spread prevention sheet of Fig. 3 taken along line DD and a cross-sectional view of the same sheet taken along line EE.

[0027] The fire spread prevention sheet 1a according to this embodiment, like the fire spread prevention sheet 1, is a sheet that is disposed at least between multiple heat sources and can prevent the spread of fire by suppressing heat transfer to other heat sources when one heat source is overheated. The fire spread prevention sheet 1a includes a heat insulating sheet 3 containing a metal oxide and capable of suppressing heat transfer from the heat source, and a rubber sheet 2 that is more elastic than the heat insulating sheet 3. A portion of the sheet end face 3a of the heat insulating sheet 3 is exposed from the outer periphery of the rubber sheet 2, but the sheet end face opposite the sheet end face 3a is not exposed from the outer periphery of the rubber sheet 2. A ventilation flow path 7 is provided between the heat insulating sheet 3 and the inside of the rubber sheet 2, allowing ventilation to the outside. The flow path 7 is a continuous flow path that includes the flow paths 4 and 5 in the first embodiment as well as a flow path 6 connecting flow path 4 and flow path 5. That is, the flow path 7 runs from a first opening 7a that opens to the side of a first sheet end face 3a included in some of the sheet end faces to a second opening 7b that is different from the first opening 7a and is formed along the outer surface of the heat insulating sheet 3 and opens to the side of the first sheet end face 3a. The first opening 7a corresponds to the first opening 4a of the flow path 4 in the first embodiment. The second opening 7b corresponds to the first opening 5a of the flow path 5 in the first embodiment.

[0028] More specifically, the flow path 7 is a generally U-shaped air passageway that extends from a first opening 7a located to the side of the first sheet end face 3a to the long side end face, short side end face, and long side end face of the cross-sectional sheet 3, and leads to a second opening 7b located to the side of the first sheet end face 3a. The second opening 7b is located on the opposite side of the first opening 7a across the sheet end face 3a. As a result, the heat insulating sheet 3 is in close contact with the rubber sheet 2 on both sides that are widest in the thickness direction, while the entire outer peripheral end face is exposed to the air.

[0029] The flow path 7 has the same configuration as the first embodiment except that it is a substantially U-shaped flow path with flow path 6 added between flow paths 4 and 5. Therefore, in the fire spread prevention sheet 1a, a description of the configuration common to the fire spread prevention sheet 1 will be omitted.

[0030] The flow paths 7 function to release heat transferred to the fire spread prevention sheet 1a to the outside. The flow paths 7 function as channels for airflow, particularly when the fire spread prevention sheet 1a is compressed in the thickness direction. Therefore, the fire spread prevention sheet 1a equipped with the flow paths 7 can effectively suppress heat transfer from one side of the sheet 1a to the other side in the thickness direction. The flow paths 7 are also formed in a roughly U-shape. Therefore, only the first sheet end surface 3a of the heat insulating sheet 3 is exposed to the outside, and the other sheet end surfaces are exposed to the flow paths 7 but are not directly exposed to the outside of the fire spread prevention sheet 1a. When the fire spread prevention sheet 1a is used with the first opening 7a and the second opening 7b of the roughly U-shaped flow paths 7 facing upward, the fire spread prevention sheet 1a has an even better ability to prevent powder from falling off when a portion of the heat insulating sheet 3 is chipped, compared to the fire spread prevention sheet 1 according to the first embodiment.

[0031] 2. Manufacturing method of fire prevention sheet Next, a method for manufacturing the fire spread prevention sheet according to one embodiment will be described. The following manufacturing method includes the manufacturing methods for both the fire spread prevention sheet 1 according to the first embodiment and the fire spread prevention sheet 1a according to the second embodiment.

[0032] Fig. 5 shows a flow of the main steps for producing a fire spread prevention sheet according to one embodiment. Fig. 6 shows a diagram for explaining the steps from the covering step to the laminating step (6A) and the cutting step (6B) in the flow of Fig. 5.

[0033] A method for manufacturing a fire spread prevention sheet in one embodiment is a method for manufacturing a fire spread prevention sheet 1, 1a that is placed at least between multiple heat sources and can prevent the spread of fire by suppressing heat transfer to other heat sources when a heat source is in an overheated state.

[0034] The method for manufacturing the fire spread prevention sheet includes a placement step (S110), a covering step (S120), a bonding step (S130), a curing step (S140), and a cutting step (S150). Note that the cutting step (S150) is not necessarily required. Below, the contents of each step will be explained, focusing mainly on the manufacture of the fire spread prevention sheet 1.

[0035] (A) Placement process (S110) This step involves placing the heat insulating sheet 3 on the first curable rubber sheet 2a. After curing, the first curable rubber sheet 2a becomes part of the rubber sheet 2. The first curable rubber sheet 2a may be laminated with a resin film 8 such as PET. The first curable rubber sheet 2a preferably contains a known foaming agent. This causes the first curable rubber sheet 2a to become a foamed rubber sheet after curing. From the placing step to the laminating step, the first curable rubber sheet 2a is preferably placed on a flat table, the heat insulating sheet 3 is placed thereon, and the second curable rubber sheet 2b is further placed thereon to create a three-layer structure. Therefore, after curing, the second curable rubber sheet 2b side of the rubber sheet 2 is likely to bulge. Furthermore, a step 10 is likely to form on the bulged side.

[0036] (B) Coating process (S120) This step involves covering the heat insulating sheet 3 with the second curable rubber sheet 2b after the above-mentioned placement step. The second curable rubber sheet 2b becomes part of the rubber sheet 2 after curing. The second curable rubber sheet 2b may be laminated with a resin film 8 such as PET. The second curable rubber sheet 2b preferably contains a known foaming agent. This causes the second curable rubber sheet 2b to become a foamed rubber sheet after curing. When referring to the first curable rubber sheet 2a and the second curable rubber sheet 2b collectively or when referring to both, they are referred to as curable rubber sheets 2a and 2b.

[0037] (C) Lamination process (S130) In this step, the first curable rubber sheet 2a and the second curable rubber sheet 2b are sandwiched between the heat insulating sheet 3 and bonded together to form flow channels 4 and 5. In a more preferred embodiment of this step, as shown in FIG. 6 (6A), a roller 9 is applied to the surface (also referred to as the sheet surface or the top surface) of the second curable rubber sheet 2b that covers one side of the heat insulating sheet 3 in the thickness direction, in a direction from the center of the surface of the heat insulating sheet 3, past positions above the flow channels, to the edges of the heat insulating sheet 3. When flow channels are present at two locations in the width direction of the heat insulating sheet 3, this step is performed by applying a roller 9 to the surface (top surface) of the second curable rubber sheet 2b that covers one side of the heat insulating sheet 3 in the thickness direction, in a direction from the center of the surface of the heat insulating sheet 3, past positions above the flow channels 4 and 5, to both widthwise ends of the curable rubber sheets 2a and 2b, to bond the sheets together. The roller 9 rotates and moves in the direction of arrow X, that is, from the center of the surface of the heat insulating sheet 3 toward the ends of the curable rubber sheets 2a and 2b. The roller 9 is a rotatable member, but it may also be a non-rotatable member. As the roller 9 moves from a high position where the heat insulating sheet 3 is present to a low position where the heat insulating sheet 3 is not present, a step 10 may be formed on the second curable rubber sheet 2b near the end of the heat insulating sheet 3. Furthermore, flow paths 4 and 5 are formed in the space near the step 10 inside the curable rubber sheets 2a and 2b.

[0038] This process is also performed when manufacturing a fire spread prevention sheet 1a having flow channels 7 at two locations in the width direction and one location in the length direction of the heat insulating sheet 3. In this process, in addition to the lamination process using the roller 9 described above, the lamination process is performed by applying the roller 9 to the surface (top surface) of the second curable rubber sheet 2b covering one side of the thickness direction of the heat insulating sheet 3, in a direction from the center of the surface of the heat insulating sheet 3, past a position above the flow channels 6, to one end in the length direction. Because the roller 9 moves from a high position where the heat insulating sheet 3 is present to a low position where the heat insulating sheet 3 is not present, a step 10 may be formed in the second curable rubber sheet 2b near the end of the heat insulating sheet 3. Furthermore, a flow channel 6 is formed in the space near the step 10 inside the curable rubber sheets 2a and 2b.

[0039] (D) Curing process (S140) This process involves curing at least the first curable rubber sheet 2a and the second curable rubber sheet 2b to integrate the first curable rubber sheet 2a, the heat insulating sheet 3, and the second curable rubber sheet 2b. This process may involve partial curing of the material of the heat insulating sheet 3. The curing process is preferably a thermal curing process. The curing process may be a single-stage process or a two-stage or more-stage process. The heating temperature in this process is preferably 180 to 230°C, more preferably 190 to 220°C. If the curing process involves multiple stages, it is preferable to change the heating temperature or heating time for each stage. The curing process causes the uncured curable rubber sheets 2a and 2b to foam and harden. This process also promotes adhesion and integration of the two rubber sheets 2 and the heat insulating sheet 3. This completes the fire spread prevention sheet 1, which is a laminate (also called a cured body) in which the heat insulating sheet 3 is sandwiched inside the rubber sheet 2 and has flow paths 4, 5 on both sides of the width of the heat insulating sheet 3, or the fire spread prevention sheet 1a, which has a continuous flow path 7 formed by adding flow path 6 to flow paths 4, 5. The flow paths 4, 5 or flow path 7 have the function of releasing heat from the fire spread prevention sheet 1, 1a, but also perform the following other functions during the manufacturing process.

[0040] The heat insulating sheet 3 may contain volatile components such as air or moisture. If the curing process is carried out with the heat insulating sheet 3 tightly covered with the curable rubber sheets 2a and 2b, the air and moisture inside the heat insulating sheet 3 cannot escape to the outside. This can cause the heat insulating sheet 3 to expand during the curing of the curable rubber sheets 2a and 2b, potentially resulting in defective products. However, if the flow paths 4 and 5 or the flow path 7 are formed before the curing process, the air or moisture can escape from the heat insulating sheet 3 to the outside through the flow paths 4 and 5 or the flow path 7 during the curing process, reducing or eliminating the problem of the heat insulating sheet 3 expanding.

[0041] (E) Cutting process (S150) This step is preferably performed when manufacturing a fire spread prevention sheet 1, and is carried out to remove the flow path 6 after it has been formed (see 6B). This step involves cutting the hardened body after the hardening step so as to remove the flow path 6 on the longitudinal side of the heat insulating sheet 3. Figure 6 (6B) illustrates an example of cutting the end side (area in the direction of arrow Y) of the fire spread prevention sheet 1, 1a from the position of line L (a position near the boundary between the end of the heat insulating sheet 3 and the flow path 6). Note that this step is not necessary if the flow path 6 is not formed, or if the flow path 6 is formed but does not need to be removed. In this sense, the cutting step is considered an optional step.

[0042] The above steps complete the production of the fire spread prevention sheets 1, 1a. If the resin film 8 is present, it may be removed immediately before, immediately after, or during the curing step, or after the cutting step.

[0043] 3. Battery FIG. 7 shows a longitudinal cross-sectional view of a battery according to one embodiment and an enlarged view of one fire spread prevention sheet sandwiched between battery cells in the longitudinal cross-sectional view.

[0044] The battery 20 according to this embodiment is, for example, a battery for an electric vehicle, and includes a plurality of battery cells (also simply referred to as "cells") 25 arranged side by side. The number of battery cells 25 is eight in this embodiment, but may be two to seven, or nine or more. The battery 20 is a storage battery, preferably a lithium-ion battery. The battery 20 includes a housing 21 with a bottom that is open on one side. The battery cells 25 are disposed inside 22 of the housing 21. The plurality of battery cells 25 are preferably pressed against each other by applying compressive force from both sides of the housing 21 using screws or the like (not shown). The bottom of the housing 21 is provided with a through-hole 23 for flowing cooling water, which is an example of a coolant. The coolant may also be referred to as a cooling medium or a coolant. The battery cells 25 are disposed inside the housing 21 with a fire-prevention sheet 1 or a fire-prevention sheet 1a sandwiched between adjacent battery cells 25.

[0045] As described above, the battery 20 according to one embodiment includes a plurality of battery cells 25 in the housing 21, and includes the fire spread prevention sheets 1, 1a at least between the battery cells 25, among between the battery cells 25 and between the battery cells 25 and the housing 21. However, the fire spread prevention sheets 1, 1a do not have to be disposed between the battery cells 25 and the housing 21.

[0046] The fire-spread prevention sheet 1, 1a disposed between the battery cells 25 is a sheet having a configuration in which a heat-insulating sheet 3 is provided inside a rubber sheet 2. When the battery cells 25 are set in the housing 21, the fire-spread prevention sheet 1, 1a is sandwiched and compressed between the battery cells 25, and the repulsive force of the fire-spread prevention sheet 1, 1a holds the battery cells 25 in the housing 21 of the battery 20. Because the fire-spread prevention sheet 1, 1a includes a rubber sheet 2, preferably a porous foam rubber sheet, it elastically deforms in its thickness direction and easily recovers to its original thickness even when the compression is subsequently released repeatedly. Furthermore, the fire-spread prevention sheet 1, 1a is compressed in its thickness direction when stored in the housing 21 in a compressed state between the battery cells 25, and is further compressed when the battery cells 25 heat and expand during charging and / or discharging of the battery 20. The rubber sheet 2 is preferably a porous sheet. Therefore, the portion of the rubber sheet 2 reduces in thickness more significantly when sandwiched and compressed between the battery cells 25.

[0047] The heat insulating sheet 3 is less likely to deform than the rubber sheet 2 and exhibits almost no cushioning properties. However, the heat insulating sheet 3 contains a non-flammable metal oxide. Therefore, even if a battery cell 25 overheats or even ignites, the fire spread prevention sheets 1, 1a can prevent the fire from spreading to other battery cells 25 due to the presence of the heat insulating sheet 3.

[0048] 4. Evaluation of thermal conductivity of fire prevention sheets Figure 8 is a diagram for explaining the method of evaluating the thermal conductivity of a fire spread prevention sheet according to the second embodiment, showing an oblique view (8A) of an area 20 mm from the end of the long side of the fire spread prevention sheet and a cross-sectional view (8B) of the vicinity of the same area during evaluation.

[0049] Three types of materials were evaluated: a foamed silicone rubber sheet (comparative material 1), a sheet (comparative material 2) consisting of a foamed silicone rubber sheet with a heat insulating sheet 3 sandwiched between it, and a fire spread prevention sheet (fire spread prevention sheet 1a according to the second embodiment) consisting of a foamed silicone rubber sheet with a heat insulating sheet 3 sandwiched between it and with flow paths 7 (cavities) formed on both sides of the heat insulating sheet 3. The area for thermal conductivity evaluation was a 20 mm area extending from the edge of the sheet beyond the flow paths.

[0050] Comparative material 1 has a total thickness of 3 mm, thermal conductivity of 0.1 W / mK, and density of 0.36 g / cm 3 The comparative material 2 is a 1 mm thick, 3 mm thick heat insulating sheet (manufactured by Awa Paper Co., Ltd., model number: I-100D, thermal conductivity: 0.05 W / mK, density: 0.30 g / cm 3 It is a composite sheet in which a 1mm thick silicone sponge sheet (made of the same material as comparative material 1) is sandwiched between two 1mm thick silicone sponge sheets. Comparative material 2 does not have any flow paths. Fire spread prevention sheet 1a is a sheet in which a flow path (opening: length 0.5mm x width 1mm) is formed in comparative material 2.

[0051] Each evaluation object was subjected to a heat conduction analysis using an analysis tool (Marc nonlinear finite element method) manufactured by MSC Software Co., Ltd. Each evaluation object sheet was sandwiched between a plate initially at 25°C and a heat source fixed at 800°C, and the temperature distribution over time was evaluated. The evaluation was carried out in 60-second intervals from the start to 300 seconds.

[0052] FIG. 9 shows the temperature distribution of Comparative Material 1 (labeled "SR sponge" in the figure), Comparative Material 2 (labeled "SR sponge + heat insulating sheet" in the figure), and Fire Spread Prevention Sheet 1a (labeled "SR sponge + heat insulating sheet + cavity" in the figure) immediately before the start of the evaluation (initial stage). FIG. 10 shows the temperature distribution of each evaluation object 60 seconds after the initial state of FIG. 9. FIG. 11 shows the temperature distribution of each evaluation object 120 seconds after the initial state of FIG. 9. FIG. 12 shows the temperature distribution of each evaluation object 180 seconds after the initial state of FIG. 9. FIG. 13 shows the temperature distribution of each evaluation object 240 seconds after the initial state of FIG. 9. FIG. 14 shows the temperature distribution of each evaluation object 300 seconds after the initial state of FIG. 9.

[0053] In the upper left of the SR sponge diagram in Figure 9, there is a bar that indicates, from bottom to top, the plate, heater, and rubber sponge by color. In the upper left of the SR sponge + heat insulating sheet and SR sponge + heat insulating sheet + cavity diagrams in Figure 9, there is a bar that indicates, from bottom to top, the plate, heater, heat insulating sheet (meaning the heat insulating sheet), and rubber sponge by color.

[0054] On the left side of each of the figures in Figures 10 to 14 for SR sponge, SR sponge + heat insulating sheet, and SR sponge + heat insulating sheet + cavity, there is a bar that indicates increasing temperatures in different colors from bottom to top in 80°C increments from 0°C to 800°C.

[0055] Comparing the temperature changes over time from the initial stage for the three evaluation targets, it was found that the SR sponge had higher thermal conductivity from the heat source to the plate than the other two types of sheets. Furthermore, when comparing the SR sponge + insulation sheet with the SR sponge + insulation sheet + cavity, it was found that after 120 seconds, the SR sponge + insulation sheet + cavity had lower thermal conductivity from the heat source to the plate than the SR sponge + insulation sheet. These results confirmed that the presence of the insulation sheet 3, and further the presence of the flow channels 7, reduces thermal conductivity in the thickness direction of the sheet.

[0056] 5. Other embodiments Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be practiced in various modified forms.

[0057] For example, the fire spread prevention sheet 1 may not have one of the flow paths 4, 5. In the rubber sheet 2 of the fire spread prevention sheet 1, 1a, the sheet surface on the side covering one side of the thickness direction of the heat insulating sheet 3 and the sheet surface on the side covering the other side of the thickness direction may both be raised in the thickness direction of the rubber sheet 2. Also, the sheet surface on the side covering one side of the thickness direction of the heat insulating sheet 3 and the sheet surface on the side covering the other side of the thickness direction may both be approximately flat. Also, the fire spread prevention sheet 1, 1a may not have the step 10 and may be smoothly inclined. Also, the step 10 may be formed on not only one side of the rubber sheet 2 in the thickness direction, but also on both sides.

[0058] The features of the claims may be combined in any combination except where they are incombinable with one another. [Industrial Applicability]

[0059] The present invention can be used in the field of preventing the spread of fire caused by an overheated state of a heat source. [Explanation of symbols]

[0060] DESCRIPTION OF SYMBOLS 1,1a...fire prevention sheet, 2...rubber sheet, 2a...first curable rubber sheet (curable rubber sheet), 2b...second curable rubber sheet (curable rubber sheet), 3...sheet end surface, 3a...first sheet end surface, 3b...second sheet end surface, 4...flow path, 4a...first opening, 4b...second opening, 5a...first opening, 5b...second opening, 6...flow path, 7...flow path, 7a...first opening, 7b...second opening, 8...resin film, 9...roller, 10...step, 20...battery, 21...casing, 25...battery cell (an example of a heat source).

Claims

1. A fire prevention sheet that is disposed at least between a plurality of heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, a heat insulating sheet capable of suppressing heat transfer from the heat source and containing a metal oxide; a rubber sheet having higher elasticity than the heat insulating sheet; Equipped with a part of the sheet end surface of the heat insulating sheet is exposed from the outer periphery of the rubber sheet; a ventilation flow path that allows ventilation between the heat insulating sheet and the inside of the rubber sheet, A fire spread prevention sheet characterized in that the flow path leads from a first opening that opens to the side of a first sheet end face included in the portion of the sheet end face to a second opening that is formed along the outer surface of the insulation sheet and opens to the side of a second sheet end face, which is another sheet end face included in the portion of the sheet end face.

2. the first sheet end surface and the second sheet end surface are opposed to each other, The fire spread prevention sheet according to claim 1, wherein two of the flow paths are formed from the end surface of the first sheet to the end surface of the second sheet.

3. A fire prevention sheet that is disposed at least between a plurality of heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, a heat insulating sheet capable of suppressing heat transfer from the heat source and containing a metal oxide; a rubber sheet having higher elasticity than the heat insulating sheet; Equipped with a part of the sheet end surface of the heat insulating sheet is exposed from the outer periphery of the rubber sheet; a ventilation flow path that allows ventilation between the heat insulating sheet and the inside of the rubber sheet, A fire spread prevention sheet characterized in that the flow path runs from a first opening that opens to the side of a first sheet end face included in the portion of the sheet end face to a second opening that is formed along the outer surface of the insulation sheet and is different from the first opening and opens to the side of the first sheet end face.

4. A fire spread prevention sheet described in any one of claims 1 to 3, characterized in that in the rubber sheet, the sheet surface on one side covering one side of the thickness direction of the insulation sheet is raised in the thickness direction of the rubber sheet compared to the sheet surface on the other side covering the other side of the thickness direction.

5. A fire spread prevention sheet as described in claim 4, characterized in that the sheet surface covering one side of the thickness direction of the insulation sheet has a step that reduces the thickness of the rubber sheet at a position above the flow path between the center of the surface of the insulation sheet, passing above the position above the flow path, and reaching the end.

6. 4. The fire spread prevention sheet according to claim 1, wherein the rubber sheet is a porous rubber sheet.

7. A fire prevention sheet according to any one of claims 1 to 3, characterized in that the heat insulating sheet contains at least one of silica, diatomaceous earth and talc as the metal oxide or material containing the metal oxide.

8. A method for manufacturing a fire prevention sheet that is disposed at least between a plurality of heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, comprising: The fire spread prevention sheet is a heat insulating sheet capable of suppressing heat transfer from the heat source and containing a metal oxide; a rubber sheet having higher elasticity than the heat insulating sheet; Equipped with a part of the sheet end surface of the heat insulating sheet is exposed from the outer periphery of the rubber sheet; a ventilation flow path that allows ventilation between the heat insulating sheet and the inside of the rubber sheet, the flow path leads from a first opening that opens to a side of a first sheet end face included in the portion of the sheet end faces to a second opening that is formed along the outer surface of the heat insulating sheet and opens to a side of a second sheet end face that is another sheet end face included in the portion of the sheet end faces, or leads from the first opening to a second opening that is formed along the outer surface of the heat insulating sheet and is different from the first opening and opens to a side of the first sheet end face, The method for producing the fire spread prevention sheet includes: a placement step of placing the heat insulating sheet on a first curable rubber sheet; a covering step of covering the heat insulating sheet with a second curable rubber sheet after the placing step; a lamination step of sandwiching the heat insulating sheet between the first curable rubber sheet and the second curable rubber sheet and laminating the first curable rubber sheet and the second curable rubber sheet together so as to form the flow path; a curing step of curing at least the first curable rubber sheet and the second curable rubber sheet to integrate the first curable rubber sheet, the heat insulating sheet, and the second curable rubber sheet; A method for producing a fire spread prevention sheet, comprising:

9. The method for manufacturing a fire spread prevention sheet as described in claim 8, characterized in that the lamination process is a process of performing a lamination process by applying a roller to the sheet surface covering one side of the thickness direction of the insulation sheet, in a direction from the center of the surface of the insulation sheet, past a position above the flow path, to the end.

10. When the flow path is present at two locations in the width direction of the heat insulating sheet, The method for manufacturing a fire spread prevention sheet as described in claim 9, characterized in that the lamination process is a process of performing a lamination process by applying the roller to the sheet surface covering one side of the thickness direction of the insulation sheet in a direction from the center of the surface of the insulation sheet, past a position above the flow path, to both ends in the width direction.

11. When the flow path is present at two locations in the width direction and one location in the length direction of the heat insulating sheet, The method for manufacturing a fire spread prevention sheet as described in claim 10, characterized in that the lamination process further comprises a step of applying the roller to the sheet surface covering one side of the thickness direction of the insulation sheet in a direction from the center of the surface of the insulation sheet, past a position above the flow path, to one end in the longitudinal direction, to perform the lamination process.

12. The method for manufacturing a fire spread prevention sheet according to claim 11, further comprising a cutting step of cutting the cured body after the curing step so as to remove the flow paths on the longitudinal side of the heat insulating sheet.

13. A battery having a plurality of battery cells in a housing, A battery comprising the fire spread prevention sheet according to claim 1 at least between the battery cells, between the battery cells and the housing.

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