Fire prevention sheet, method for producing fire prevention sheet, and battery

Abstract

To provide a fire spread prevention sheet that reduces heat transfer between a plurality of heat sources and has excellent fire spread prevention performance; a method for manufacturing the same; and a battery.SOLUTION: There is provided a fire spread prevention sheet 1 that is arranged at least between a plurality of heat sources, can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat source is in an overheated state. The fire spread prevention sheet 1 comprises: a rubber sheet 2 made of a rubber-like elastic body; a heat insulating sheet 3 that is laminated on both sides of the rubber sheet 2 and can reduce heat transfer between a plurality of adjacent heat sources; and an adhesive layer 5 that is interposed between the rubber sheet 2 and the heat insulating sheet 3, and bonds the heat insulating sheet 3 to both sides of the rubber sheet 2 in which the adhesive layer 5 is arranged in a line shape in a plan view of the rubber sheet 2. There are also provided a method for manufacturing a fire spread prevention sheet, and a battery.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Currently, worldwide, for the purpose of reducing the load on the global environment, there is an active movement to gradually convert conventional gasoline vehicles or diesel vehicles into electric vehicles. In particular, in addition to European countries such as France, the Netherlands, and Germany, the spread of electric vehicles is also progressing in China. However, for the spread of electric vehicles, in addition to the development of high-performance batteries, there are issues such as the installation of a large number of charging stations.

[0003] Various batteries such as the above-mentioned automotive batteries may cause thermal runaway of the battery due to internal short circuits or the like, resulting in ignition, smoke generation, or the like. In recent years, as an automotive battery, one in which a plurality of battery cells are arranged and mounted in a housing is known. In such a battery in which a plurality of battery cells are arranged and mounted, when ignition, smoke generation, or the like occurs from one battery cell, heat may be transferred to the surrounding battery cells, leading to further problems such as larger ignition, smoke generation, and explosion. In order to minimize the damage caused by such problems, methods for making it difficult to transfer the heat of an abnormally heated battery cell to the surrounding battery cells have been studied. For example, a method of providing a fire spread prevention sheet such as a refractory material or a heat insulation layer between a plurality of battery cells is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although the conventionally known flame spread prevention sheet can exhibit corresponding characteristics, further improvement in heat insulation performance is required. That is, there is a demand for a flame spread prevention sheet that further reduces heat conduction between a plurality of battery cells and has an excellent flame spread prevention function. The above requirement is applicable not only to battery cells but also to other heat sources such as circuit boards, electronic components, or the main body of electronic devices. Further, the present invention can be used for secondary batteries mounted on environmentally considerate electric vehicles and also contributes to the achievement of the applicant's sustainable development goal of "ensuring all people's access to affordable, reliable, and sustainable modern energy."

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a flame spread prevention sheet, a method for manufacturing the flame spread prevention sheet, and a battery that reduce heat transfer between a plurality of heat sources and have excellent flame spread prevention performance.

Means for Solving the Problems

[0007] (1) A flame spread prevention sheet according to an embodiment for achieving the above object is a flame spread prevention sheet that is at least disposed between a plurality of heat sources and can prevent flame spread by suppressing heat transfer to other heat sources when the heat source is in an overheated state. The flame spread prevention sheet includes a rubber sheet made of a rubber-like elastic body, a heat insulation sheet laminated on both surfaces of the rubber sheet and capable of reducing heat transfer between adjacent plurality of the heat sources, and an adhesive layer interposed between the rubber sheet and the heat insulation sheet and bonding the heat insulation sheet to both surfaces of the rubber sheet. The adhesive layer is provided in a line shape or a lattice shape in a plan view of the rubber sheet. (2) In a flame spread prevention sheet according to another embodiment, preferably, the adhesive layer is composed of a first adhesive layer that bonds the heat insulation sheet to one surface of the rubber sheet and a second adhesive layer that bonds the heat insulation sheet to the other surface of the rubber sheet. The first adhesive layer and the second adhesive layer are provided in a line shape or a lattice shape in a plan view of the rubber sheet, and the second adhesive layer may be provided at a position different from that of the first adhesive layer in a thickness direction from the one surface of the rubber sheet toward the other surface of the rubber sheet. (3) In the fire spread prevention sheet according to another embodiment, preferably, the rubber sheet may be mainly composed of a porous body. (4) In the fire spread prevention sheet according to another embodiment, preferably, the rubber sheet may be a foamed sheet of silicone rubber. (5) A method for manufacturing a fire spread prevention sheet according to an embodiment for achieving the above object is a method for manufacturing any of the above fire spread prevention sheets, including an adhesive layer forming step of applying an adhesive in a line shape or a lattice shape in a plan view of the rubber sheet on both surfaces of the rubber sheet made of a rubber-like elastic body to form an adhesive layer, and a lamination step of laminating a heat insulating sheet capable of reducing heat transfer between adjacent plurality of the heat sources on the adhesive layer and bonding the rubber sheet and the heat insulating sheet via the adhesive layer. (6) A battery according to an embodiment for achieving the above object includes a plurality of battery cells, and includes any of the above fire spread prevention sheets at least between the battery cells and / or between the battery cells and the housing.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a fire spread prevention sheet having excellent fire spread prevention performance by reducing heat transfer between a plurality of heat sources, a method for manufacturing the fire spread prevention sheet, and a battery.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

MODE FOR CARRYING OUT THE INVENTION

[0010] Next, each embodiment of the present invention will be described with reference to the drawings. Note that each embodiment described below does not limit the invention according to the claims, and not all of the elements and combinations thereof described in each embodiment are essential for the solution means of the present invention.

[0011] 1. Fire spread prevention sheet FIG. 1 shows a perspective view of a fire spread prevention sheet according to an embodiment of the present invention. FIG. 2 shows a perspective view, a partially enlarged sectional view in the X-Z plane, and a sectional view in the X-Y plane of the fire spread prevention sheet of FIG. 1, respectively. In the present embodiment, a plane parallel to the plane of the fire spread prevention sheet is defined as an X-Y plane including X and Y axes orthogonal to each other, and an axis perpendicular to the X-Y plane (that is, the axis in the thickness direction of the fire spread prevention sheet) is defined as the Z axis. In FIG. 2, the sectional view in the X-Y plane means a plane when the thickness of the fire spread prevention sheet is cut parallel to the sheet surface (X-Y plane). The sectional view in the X-Z plane means a plane when the fire spread prevention sheet is cut parallel to the thickness direction of the sheet by the X-Z plane.

[0012] The fire spread prevention sheet 1 according to this embodiment is, for example, a sheet that is at least disposed between a plurality of heat sources such as a plurality of battery cells inside a battery, and that can suppress heat transfer to other heat sources when the heat source is in an overheated state to prevent fire spread. The fire spread prevention sheet 1 includes a rubber sheet 2 made of a rubber-like elastic body, a heat insulation sheet 3 laminated on both surfaces of the rubber sheet 2 and capable of reducing heat transfer between adjacent plurality of heat sources, and an adhesive layer 5 interposed between the rubber sheet 2 and the heat insulation sheet 3 and bonding the heat insulation sheet 3 to both surfaces of the rubber sheet 2. The adhesive layer 5 is provided in a line shape in a plan view of the rubber sheet 2 (see FIG. 2). Next, each component of the fire spread prevention sheet 1 will be described.

[0013] (1) Rubber sheet The rubber sheet 2 is a sheet made of a rubber-like elastic body. Instead of the phrase "rubber-like elastic body", the phrases "elastic body" or "cushion member" may be used. The rubber sheet 2 is located between multiple heat sources, functions to exhibit cushioning properties and enhance the adhesion between the heat source and the heat insulation sheet 3, and also functions as a protective member to prevent the heat insulation sheet 3 from being damaged by the load applied to the heat insulation sheet 3. The rubber sheet 2 is mainly composed of a porous body, preferably a porous rubber sheet. Here, "mainly" means occupying more than 50% of the volume. The meaning of "mainly" hereafter is the same. The rubber sheet 2 may be composed only of a porous body, a sheet in which the porous body occupies 90%, or a sheet in which the porous body occupies 80 - 51%. The porous rubber sheet is a sponge-like member having air bubbles inside. The air in the pores of the sponge has excellent heat insulation properties. Therefore, the sponge-like member contributes to the low thermal conductivity of the flame retardant sheet 1. Examples of the rubber include 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), as well as thermoplastic elastomers such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based, fluorine-based, or their composites, etc. Among the rubbers, silicone rubber with relatively high heat resistance can be more preferably used. The rubber sheet 2 is most preferably a foamed sheet of silicone rubber. The rubber sheet 2 may contain halogen compounds, phosphorus compounds, platinum, inorganic compounds such as magnesium hydroxide or aluminum hydroxide in order to enhance the flame retardant performance. The thickness of the rubber sheet 2 is not particularly restricted, but is preferably 1 - 20 mm, more preferably 2 - 8 mm.

[0014] (2) Heat insulation sheet The heat insulation sheet 3 has a function of effectively preventing the spread of fire between a plurality of heat sources. The heat insulation sheet 3 is preferably a sheet excellent in heat resistance and flame retardancy, and more preferably has higher heat resistance than the rubber sheet 2 and is composed of a material with high flame retardancy. The heat insulation sheet 3 may be made of any material, for example, fibrous heat insulating materials such as non-woven fabric, glass wool, rock wool, cellulose fiber, polyolefin foams such as polystyrene foam, polyethylene foam, polypropylene foam, plastic heat insulating materials such as rigid urethane foam, phenolic foam, acrylic foam, silicone foam, and nanoporous materials such as aerogel. Further, the heat insulation sheet 3 may be a silica aerogel sheet in which silica aerogel is impregnated and supported with a sheet-like fiber mass as a carrier. As the sheet-like fiber mass, glass fiber; ceramic fibers such as silica fiber, alumina fiber, titania fiber, silicon carbide fiber; metal fiber; man-made mineral fibers such as rock wool, basalt fiber; carbon fiber; whiskers, etc. can be made into a paper-like or board-like shape by a papermaking method, or a sheet-like molded product such as a non-woven fabric, mat, felt, etc. formed into a sheet shape by appropriately adding a binder can be used. Among these, in order to effectively obtain the heat insulation effect of silica aerogel, a carrier that can maintain its shape as a carrier even at the heat resistance temperature of silica aerogel (about 750 °C) is more preferable. The porosity of the silica aerogel is preferably 60% or more, and more preferably 80% or more. The silica aerogel may simply be impregnated and dispersed in the sheet-like fiber mass, or may be supported in the form of constituent fibers of the sheet-like fiber mass using a binder or the like. Further, in addition to silica aerogel, the heat insulation sheet 3 may be a sheet provided with one or more of steatite (MgO·SiO 2 ), zirconia (ZrO 2 ), cordierite (2MgO·2Al 2 O 3 ·5SiO 2 ), forsterite (2MgO·SiO 2 ), or mullite (3Al 2 O 3 ·2SiO 2 ).

[0015] The heat insulation sheet 3 does not matter whether it has excellent conductivity. The heat insulation sheet 3 is preferably a sheet excellent in curvature (or bendability), and there is no restriction on its thickness, but 0.02 to 3.0 mm is preferable, and 0.1 to 2.0 mm is more preferable. The thickness of the heat insulation sheet 3 is preferably smaller than the thickness of the rubber sheet 2. However, the thickness of the heat insulation sheet 3 is preferably determined in consideration of the strength, flexibility and heat resistance of the sheet.

[0016] (3) Adhesive layer The adhesive layer 5 is a layer containing an adhesive or a cured product thereof that adheres the rubber sheet 2 and the heat insulation sheet 3. The adhesive is not particularly limited as long as it can adhere the rubber sheet 2 and the heat insulation sheet 3. For example, epoxy adhesives, urethane adhesives, acrylic adhesives, melamine adhesives, polyester adhesives, silicone adhesives, etc. can be used. Among these, it is preferable to use a silicone adhesive excellent in heat resistance and rubber elasticity. In this embodiment, the adhesive layer 5 is a layer formed by curing a curable silicone-based adhesive, and can also be referred to as a cured product of self-adhesive silicone rubber. The adhesive that becomes the material of such an adhesive layer 5 is a kind of solvent-free silicone-based adhesive, has a high adhesive strength, and has heat stability, weather resistance, good water resistance, and excellent plasticity after curing.

[0017] The next layer 5 is preferably composed of a first adhesive layer 5a that adheres the heat insulation sheet 3 to one surface of the rubber sheet 2 and a second adhesive layer 5b that adheres the heat insulation sheet 3 to the other surface of the rubber sheet 2. The first adhesive layer 5a and the second adhesive layer 5b are preferably provided in a plurality of line shapes in a plan view of the rubber sheet 2 (see the cross-sectional view in the X-Y plane of FIG. 2). More specifically, the first adhesive layer 5a is a layer formed by curing an adhesive applied in a line shape in a plan view on one surface of the rubber sheet 2. The second adhesive layer 5b is a layer formed by curing an adhesive applied in a line shape in a plan view on the other surface of the rubber sheet 2. That is, the first adhesive layer 5a and the second adhesive layer 5b preferably have a plurality of line-shaped voids 10 in the space sandwiched between the rubber sheet 2 and the heat insulation sheet 3. The second adhesive layer 5b is preferably provided at a position different from that of the first adhesive layer 5a in the thickness direction (Z-axis direction in FIG. 2) from one surface of the rubber sheet 2 toward the other surface (see the partially enlarged cross-sectional view in the X-Z plane of FIG. 2). That is, the second adhesive layer 5b is arranged at a position shifted from the first adhesive layer 5a in the Z direction. With such a configuration, the compression load of the fire spread prevention sheet 1 can be reduced.

[0018] In the first adhesive layer 5a and the second adhesive layer 5b, the distance between any two adjacent lines is not particularly restricted. However, when the flame retardant sheet 1 is compressed by adjacent heat sources, it is preferable that the rubber sheet 2 does not enter the gap 10 and bury the gap 10. As such a grid interval, 1 mm to 20 mm is preferable, and 3 mm to 8 mm is more preferable. Also, the distance between the above two lines is not limited to an equal interval. For example, the distance between the lines may vary depending on the location. Further, the line shapes of the first adhesive layer 5a and the second adhesive layer 5b do not follow the longitudinal and lateral directions of the rubber sheet 2. For example, they may be diagonal line shapes inclined with respect to the longitudinal and lateral directions of the rubber sheet 2. Also, the first adhesive layer 5a and the second adhesive layer 5b do not have to be layers formed in line shapes facing the same direction, and may be layers facing different directions. For example, the second adhesive layer 5b may be formed by rotating the first adhesive layer 5a by 90 degrees. In that case, in a plan view of the transmission plane in the thickness direction of the flame retardant sheet 1, a grid-like adhesive layer is formed by the first adhesive layer 5a and the second adhesive layer 5b.

[0019] According to the flame retardant sheet 1 configured as described above, since the adhesive layer 5 (the first adhesive layer 5a and the second adhesive layer 5b) that adheres the rubber sheet 2 and the heat insulating sheet 3 is provided in a plurality of line shapes in a plan view of the rubber sheet 2, a line-shaped gap 10 is formed between the rubber sheet 2 and the heat insulating sheet 3. The air present in the gap 10 forms a heat insulating layer. Therefore, the flame retardant sheet 1 can reduce heat transfer between a plurality of heat sources and improve the flame retardant performance.

[0020] 2. Modification example of the flame retardant sheet FIG. 3 shows a perspective view, a partially enlarged cross-sectional view in the X-Z plane, and a cross-sectional view in the X-Y plane of a modification example of the flame retardant sheet of FIG. 1. In FIG. 3, the cross-sectional view in the X-Y plane means a plane when the thickness of the flame retardant sheet is cut parallel to the sheet surface (X-Y plane). The cross-sectional view in the X-Z plane means a plane when the flame retardant sheet is cut parallel to the thickness direction of the sheet by the X-Z plane.

[0021] The fire spread prevention sheet 1 according to the modified example shown in FIG. 3 includes a rubber sheet 2 and a heat insulation sheet 3 common to the fire spread prevention sheet 1 shown in FIG. 1. The difference between the fire spread prevention sheet 1 according to the modified example and the fire spread prevention sheet 1 shown in FIG. 1 is that, in addition to the linear adhesive layer 5, it is provided with an adhesive layer 6 that intersects the adhesive layer 5. Hereinafter, the differences from the fire spread prevention sheet 1 shown in FIG. 1 will be mainly described.

[0022] Adhesive layer The adhesive layers 5 and 6 are layers containing an adhesive for adhering the rubber sheet 2 and the heat insulation sheet 3 or a cured product thereof. The adhesive layer 6 is composed of the same adhesive as the above-described adhesive layer 5. The adhesive layer 6 is preferably composed of a first adhesive layer 6a that adheres the heat insulation sheet 3 to one surface of the rubber sheet 2 and a second adhesive layer 6b that adheres the heat insulation sheet 3 to the other surface of the rubber sheet 2. The first adhesive layers 5a and 6a are preferably provided in a lattice pattern in a plan view of the rubber sheet 2. Similarly, the second adhesive layers 5b and 6b are also preferably provided in a lattice pattern in a plan view of the rubber sheet 2 (see a cross-sectional view in the X-Y plane of FIG. 3). More specifically, the first adhesive layers 5a and 6a are layers formed by curing an adhesive applied in a lattice pattern on one surface of the rubber sheet 2 in a plan view. The second adhesive layers 5b and 6b are layers formed by curing an adhesive applied in a lattice pattern on the other surface of the rubber sheet 2 in a plan view. The first adhesive layers 5a and 6a preferably have a plurality of lattice-shaped voids 10 in the space sandwiched between the rubber sheet 2 and the heat insulation sheet 3. The second adhesive layers 5b and 6b are preferably provided at positions different from those of the first adhesive layers 5a and 6a in the thickness direction (Z-axis direction in FIG. 3) from one surface of the rubber sheet 2 to the other surface (see a partially enlarged cross-sectional view in the X-Z plane of FIG. 3). The second adhesive layer 5b is arranged at a position shifted from the first adhesive layer 5a in the Z direction. The second adhesive layer 6b is also arranged at a position shifted from the first adhesive layer 6a in the Z direction. With such a configuration, the compression load of the fire spread prevention sheet 1 can be reduced.

[0023] Note that the size of the grids formed by the first adhesive layers 5a and 6a and the second adhesive layers 5b and 6b is not particularly limited. However, when the fire spread prevention sheet 1 is compressed by adjacent heat sources, it is preferable that the size is such that the rubber sheet 2 can enter the void 10 and does not bury the void 10. As such a grid size, the longitudinal and lateral lengths are preferably both 1 mm to 20 mm, and more preferably 3 mm to 8 mm. Further, the intervals between adjacent first adhesive layers 5a, between adjacent first adhesive layers 6a, between adjacent second adhesive layers 5b, and between adjacent second adhesive layers 6b are not limited to equal intervals. For example, the intervals may vary depending on the location. Also, the first adhesive layers 5a and 6a do not have to be along the longitudinal and transverse directions of the rubber sheet 2, and may be, for example, in an oblique line shape inclined with respect to the longitudinal and transverse directions of the rubber sheet 2. Similarly, the second adhesive layers 5b and 6b do not have to be along the longitudinal and transverse directions of the rubber sheet 2, and may be, for example, in an oblique line shape inclined with respect to the longitudinal and transverse directions of the rubber sheet 2. Further, the grid formed by the second adhesive layers 5b and 6b may be rotated with respect to the grid formed by the first adhesive layers 5a and 6a. For example, the grid of the second adhesive layers 5b and 6b may be formed to be rotated 45 degrees with respect to the grid of the first adhesive layers 5a and 6a. It may be formed like this.

[0024] According to the fire spread prevention sheet 1 configured as described above, the adhesive layer 5 (the first adhesive layer 5a and the second adhesive layer 5b) that adheres the rubber sheet 2 and the heat insulating sheet 3 and the adhesive layer 6 (the first adhesive layer 6a and the second adhesive layer 6b) are each provided in a grid pattern in a plan view of the rubber sheet 2. Therefore, a grid-shaped void 10 is formed between the rubber sheet 2 and the heat insulating sheet 3. The air present in the void 10 forms a heat insulating layer. Thus, the fire spread prevention sheet 1 can reduce the heat transfer between a plurality of heat sources and improve the fire spread prevention performance.

[0025] 3. Method for manufacturing the fire spread prevention sheet Next, an example of a preferred method for manufacturing the fire spread prevention sheet according to the embodiment of the present invention will be described.

[0026] FIG. 4 shows an example of the flow of the main steps of the method for manufacturing a fire spread prevention sheet according to an embodiment of the present invention.

[0027] The method for manufacturing a fire spread prevention sheet according to this embodiment is a method for manufacturing the fire spread prevention sheet 1 described above. The method for manufacturing the fire spread prevention sheet 1 is common to various fire spread prevention sheets 1 in which the adhesive layer is formed in a line shape and a lattice shape. The manufacturing method includes an adhesive layer forming step (S110) and a laminating step (S120). Further, the method for manufacturing the fire spread prevention sheet 1 preferably includes a rubber sheet manufacturing step (S100). Hereinafter, each step will be described.

[0028] (1) Rubber sheet manufacturing step (S100) The rubber sheet manufacturing step is a step of manufacturing a rubber sheet 2 made of a rubber-like elastic body. More specifically, first, a silicone rubber, a crosslinking agent, a coloring agent, etc., which are the materials of the rubber sheet 2, are kneaded using a kneader such as a mixing roll and separated into a sheet shape. Next, the sheet-shaped molded product is cured by heat treatment to produce the rubber sheet 2. In the method for manufacturing a fire spread prevention sheet, for example, when the rubber sheet 2 can be prepared without manufacturing it by means such as purchase, the rubber sheet manufacturing step (S100) may be omitted.

[0029] (2) Adhesive layer forming step (S110) The next layer formation step is a step of forming an adhesive layer 5, or adhesive layers 5 and 6, by applying an adhesive in a line shape or a grid shape in a plan view of the rubber sheet 2 on both surfaces of the rubber sheet 2 made of a rubber-like elastic body. In this embodiment, the adhesive is preferably a curable silicone-based adhesive in an uncured state (or semi-cured state). That is, in this embodiment, the adhesive layer formation step is a step of forming an uncured adhesive layer by applying an adhesive in a line shape or a grid shape in a plan view of the rubber sheet 2 on both surfaces of the rubber sheet 2. More specifically, in the adhesive layer formation step, first, an adhesive is applied in a line shape or a grid shape in a plan view on one surface of the rubber sheet 2 to form a first adhesive layer in an uncured state. At this time, the first adhesive layer in the uncured state includes voids 10 arranged in a line shape or a grid shape. Next, an adhesive is applied in a line shape or a grid shape in a plan view on the other surface of the rubber sheet 2 to form a second adhesive layer in an uncured state. At this time, the second adhesive layer also includes voids 10 arranged in a line shape or a grid shape. Further, the second adhesive layer is preferably provided at a position different from that of the first adhesive layer in the thickness direction from one surface of the rubber sheet 2 toward the other surface.

[0030] (3) Laminating step (S120) The laminating step is a step of laminating a heat insulating sheet 3 capable of reducing heat transfer between adjacent plurality of heat sources on the adhesive layer 5, or the adhesive layers 5 and 6, and bonding the rubber sheet 2 and the heat insulating sheet 3 through these adhesive layers. Then, the adhesive layer 5, or the adhesive layers 5 and 6 can be cured to manufacture the fire spread prevention sheet 1. The curing is preferably performed by leaving it at room temperature in the air or heating it in the air. However, the curing method is not limited to leaving it at room temperature or heating, and may be performed by irradiation with ultraviolet rays or electron beams, or even by another method.

[0031] Note that, for the method of manufacturing the fire spread prevention sheet, the adhesive layer forming step (S110) and the lamination step (S120) may be performed on each side of the rubber sheet 2. More specifically, a first adhesive layer may be formed on one surface of the rubber sheet 2, and the heat insulation sheet 3 may be laminated on the first adhesive layer to bond the heat insulation sheet 3 to one surface of the rubber sheet 2. Next, a second adhesive layer may be formed on the other surface of the rubber sheet 2, and the heat insulation sheet 3 may be laminated on the second adhesive layer to bond the heat insulation sheet 3 to the other surface of the rubber sheet 2, and the first adhesive layer and the second adhesive layer may be cured to manufacture the fire spread prevention sheet 1.

[0032] 4. Battery Next, a battery including the fire spread prevention sheet according to the embodiment of the present invention will be described.

[0033] FIG. 5 shows a longitudinal sectional view of a battery including the fire spread prevention sheet according to the embodiment of the present invention.

[0034] Here, the "longitudinal sectional view" means a cross-section obtained by cutting the battery in the length direction (i.e., the height direction) of the battery cells inside the battery housing. Also, in FIG. 5, the battery includes 12 battery cells, but the number of battery cells is not particularly limited.

[0035] The battery 40 illustrated in FIG. 5 is, for example, a battery for an electric vehicle and includes a number of battery cells 30 (an example of a heat source). The battery 40 includes a bottomed housing 41 that is open on one side. The housing 41 is preferably made of aluminum or an aluminum-based alloy. The battery 40 includes a plurality of battery cells 30 within the housing 41. The battery cells 30 are arranged inside the housing 41 at 44. Electrodes are provided protruding above the battery cells 30. The plurality of battery cells 30 are preferably given a force in a compressing direction using screws or the like from both sides within the housing 41 so as to be in close contact with each other (not shown). At the bottom 42 of the housing 41, one or a plurality of water-cooling pipes 43 are provided for flowing cooling water, which is an example of the coolant 45. The coolant 45 may also be referred to as a cooling medium or a coolant. The above-described fire spread prevention sheet 1 is provided at least between the battery cells 30 and / or between the battery cells 30 and the housing 41. The battery 40 according to this embodiment sandwiches the fire spread prevention sheet 1 between both the battery cells 30 and between the battery cells 30 and the housing 41.

[0036] In the battery 40, the fire spread prevention sheet 1 is preferably arranged such that its widest surface is in contact with the widest side surface of the battery cell 30. In the battery 40 illustrated in FIG. 5, one fire spread prevention sheet 1 is arranged between the side surface of the interior 44 of the housing 41 and the battery cell 30, and between adjacent battery cells 30. However, in the battery 40, the fire spread prevention sheet 1 need not be arranged between all adjacent battery cells 30 as long as it is arranged between at least two adjacent battery cells 30. Also, the fire spread prevention sheet 1 need not be arranged between the side surface of the interior 44 of the housing 41 and the battery cell 30. Further, in the battery 40, a plurality of fire spread prevention sheets 1 may be arranged between adjacent battery cells 30.

[0037] In this embodiment, the fire spread prevention sheet 1 has substantially the same size as the widest surface (side surface) of the battery cell 30, but it may be larger or smaller than the side surface. However, in order to enhance the fire spread prevention performance, it is preferable that the fire spread prevention sheet 1 is the same as or larger than the side surface of the battery cell 30.

[0038] Thus, by arranging the fire spread prevention sheet 1 between a plurality of battery cells 30 inside the battery 40, heat transfer to other battery cells 30 can be suppressed even when the battery cell 30 is in an overheated state. Further, the fire spread prevention sheet 1 can further reduce heat transfer between a plurality of battery cells 30 by including a filler having a lower thermal conductivity than the adhesive in the adhesive layers 5 and 6, and can improve the fire spread prevention performance.

[0039] <Other Embodiments> As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to these and can be implemented with various modifications.

[0040] For example, the above-described fire spread prevention sheet 1 is a sheet having a substantially rectangular parallelepiped shape, but is not limited thereto, and may be, for example, an ellipse, a circle, a triangle, a polygon, or the like. The shape of the fire spread prevention sheet 1 is preferably appropriately designed according to the shape of the heat source, the application, and the like.

[0041] Further, in the fire spread prevention sheet 1, the second adhesive layer 5b (or the second adhesive layer 6b) does not necessarily have to be provided at a position different from that of the first adhesive layer 5a (or the first adhesive layer 6a) in the thickness direction from one surface to the other surface of the rubber sheet 2.

[0042] Further, the heat source includes not only the battery cell 30 but also all objects that generate heat, such as a circuit board and an electronic device body. For example, the heat source may be an electronic component such as a capacitor and an IC chip.

Example

[0043] Next, examples of the present invention will be described while comparing them with comparative examples. Note that the present invention is not limited to the following examples.

[0044] 1. Main raw materials of the adhesive layer As the adhesive serving as the constituent material of the adhesive layer of the flame retardant sheet, a silicone adhesive was used. For the silicone adhesive, KE-2090-50A and KE-2090-50B manufactured by Shin-Etsu Chemical Co., Ltd. were used.

[0045] 2. Rubber sheet As the rubber sheet serving as the constituent material of the flame retardant sheet, a silicone sponge prepared as follows was used. First, 100 parts by mass of a curable silicone rubber composition (product number: KE-9710U manufactured by Shin-Etsu Chemical Co., Ltd.), 0.3 parts by mass of an organic peroxide crosslinking agent (product number: C-1A manufactured by Shin-Etsu Chemical Co., Ltd.), 2.0 parts by mass of an organic peroxide crosslinking agent (product number: C-3 manufactured by Shin-Etsu Chemical Co., Ltd.), and 2.0 parts by mass of an addition reaction type crosslinking agent (product number: C-25A manufactured by Shin-Etsu Chemical Co., Ltd.) were prepared, and 1.0 part by mass of a foaming agent and 1.0 part by mass of a coloring agent were added thereto, and these were kneaded using a mixing roll. Here, 1 part by mass corresponds to 1 g. The same applies to the description of the following examples. While separating the kneaded mixture into a sheet shape using a mixing roll, a polyethylene terephthalate (PET) film was attached to one surface of the sheet-shaped molded product. Next, the separated sheet-shaped molded product was peeled off from the mixing roll, and the above PET film was also attached to the other surface. This sheet-shaped molded product was left standing in a thermostatic bath heated to 195°C and primary vulcanized for 5 minutes. Then, the sheet-shaped molded product was taken out of the thermostatic bath and the PET films attached to both surfaces were peeled off, and a silicone sponge with a thickness of 5 mm was produced by secondary vulcanization at 200°C for 4 hours.

[0046] 3. Heat insulation sheet As the heat insulation sheet serving as the constituent material of the flame retardant sheet, a heat insulation sheet (product number: I-80F, thickness 0.8 mm) manufactured by Awa Paper Co., Ltd. was used.

[0047] 4. Evaluation method (Thermal chain test) FIG. 6 shows a photograph of a test apparatus for a thermal chain reaction test and a magnified photograph of a part D thereof, respectively.

[0048] The thermal chain reaction test of the flame spread prevention sheet was conducted as follows using the test apparatus shown in FIG. 6. The temperature of the heat source metal plate 21 simulating an abnormally heating battery cell is raised to 600°C. Next, a sample S is placed between the heat source metal plate 21 simulating the time of abnormal heating and the metal plate 22 simulating a battery cell adjacent thereto. Next, the heat source metal plate 21 is pushed at 30 kPa with an air cylinder so that the heat insulating sheet of the heat source metal plate 21 and the sample S are in contact with each other. Next, the temperature profile of the metal plate 22 on the bottom surface side of the heat insulating sheet is recorded for 15 minutes. The maximum temperature reached by the metal plate 22 is the t of the heat source metal plate 21 1 position and the t of the metal plate 22 2 position is measured by providing thermocouples.

[0049] 5. Manufacture of Samples of Flame Spread Prevention Sheets <Example> (1) Example 1 An adhesive obtained by kneading 50 parts by mass of a silicone adhesive (product number: KE-2090-50A) and 50 parts by mass of a silicone adhesive (product number: KE-2090-50B) was applied to both sides of a silicone sponge in a line shape (see FIG. 2) in a plan view using a metal spatula and / or a syringe (this application method is referred to as "line"). The interval between adjacent lines was 5 mm, and the width of the line was 1 mm. Next, a heat insulating sheet was laminated on each of the adhesives applied in a plurality of lines, and vulcanized in a constant temperature bath at 170°C for 5 minutes to produce a sample of a circular flame spread prevention sheet having a diameter of 50 mm. The sample was evaluated by the above evaluation method.

[0050] (2) Example 2 Except for the application form of the adhesive, the same conditions as in Example 1 were adopted. Specifically, the adhesive used in Example 1 was applied to both sides of the silicone sponge in a grid pattern (see Figure 3) in a plan view (this application method is referred to as "grid"). The vertical and horizontal lengths of the grid were 5 mm, and the width of the lines constituting the grid was 1 mm. Next, a heat insulation sheet was laminated on the adhesive applied in a grid pattern, and a sample of the flame spread prevention sheet was produced under the same conditions as in Example 1. The samples were evaluated by the above evaluation method.

[0051] <Comparative Example> Comparative Example 1 Except for the application form of the adhesive, the same conditions as in Example 1 were adopted. The adhesive used in Example 1 was applied to the entire area of both sides of the silicone sponge (this application method is referred to as "normal"). Next, a heat insulation sheet was laminated on the adhesive in a full-surface application state, vulcanized in a constant temperature bath at 170°C for 5 minutes, and a sample of a circular flame spread prevention sheet with a diameter of 50 mm was produced. This sample is a flame spread prevention sheet in which the adhesive is applied to the entire surface of the silicone sponge and the adhesive layer has no voids. The samples were evaluated by the above evaluation method.

[0052] 6. Results and Discussion Next, the results of the thermal chain test in which each test piece of Example 1, 2 and Comparative Example 1 was brought into contact with a heat source at 600°C are shown.

[0053] Table 1 shows the temperature and thermal conductivity for each adhesive pattern. Figure 7 is a graph of the thermal chain test results, showing the time change of the temperature on the bottom surface side.

[0054]

Table 1

[0055] As is clear from Table 1 and FIG. 7, it was found that the maximum temperature difference after 900 seconds in the thermal chain test was 5.2 (°C), and the thermal conductivity was 0.028 (W / m·K). The adhesive application patterns, in ascending order of low thermal conductivity, were line pattern → grid pattern → normal pattern. This is presumably because the line pattern had the most gaps between the heat insulation sheet and the silicone sponge, and the small number of heat transfer paths from the heat source led to low thermal conductivity.

Industrial Applicability

[0056] The flame spread prevention sheet according to the present invention can be used in various batteries such as automotive batteries, rechargeable household batteries, and batteries for electronic devices such as PCs, as well as various electronic devices such as automobiles, industrial robots, power generation devices, PCs, and household electrical appliances.

Explanation of Symbols

[0057] 1... Flame spread prevention sheet, 2... Rubber sheet, 3... Heat insulation sheet, 5, 6... Adhesive layer, 5a, 6a... First adhesive layer, 5b, 6b... Second adhesive layer, 10... Gap, 30... 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 can prevent the spread of fire by suppressing heat transfer to other heat sources when the heat sources are in an overheated state, A rubber sheet made of a rubber-like elastic material; a heat insulating sheet laminated on both sides of the rubber sheet and capable of reducing heat transfer between adjacent heat sources; an adhesive layer interposed between the rubber sheet and the heat insulating sheet and bonding the heat insulating sheet to both sides of the rubber sheet; Equipped with The adhesive layer is a first adhesive layer that adheres the heat insulating sheet to one surface of the rubber sheet; a second adhesive layer that adheres the heat insulating sheet to the other surface of the rubber sheet; It is composed of the first adhesive layer and the second adhesive layer are provided in a line shape or a lattice shape in a plan view of the rubber sheet, A fire spread prevention sheet characterized in that the second adhesive layer is provided at a different position from the first adhesive layer in the thickness direction from the one surface to the other surface of the rubber sheet.

2. 2. The fire prevention sheet according to claim 1, wherein the rubber sheet is mainly composed of a porous material.

3. 3. The fire prevention sheet according to claim 2, wherein the rubber sheet is a foamed silicone rubber sheet.

4. A method for producing the fire spread prevention sheet according to any one of claims 1 to 3, an adhesive layer forming step of applying an adhesive to both sides of a rubber sheet made of a rubber-like elastic material in a line or lattice pattern in a plan view of the rubber sheet to form adhesive layers; a lamination step of laminating a heat insulating sheet capable of reducing heat transfer between adjacent heat sources on the adhesive layer and bonding the rubber sheet and the heat insulating sheet via the adhesive layer; A method for producing a fire spread prevention sheet comprising the steps of:

5. A battery comprising a plurality of battery cells, and a fire spread prevention sheet according to any one of claims 1 to 3 provided at least either between the battery cells or between the battery cells and a housing.

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