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Abstract

The present invention aims to provide a sheet that can suppress deformation of the sheet when a heat-expandable fire-resistant coating layer expands. [Solution] The sheet of the present invention comprises a glass cloth and a heat-expandable fire-resistant coating layer laminated on the glass cloth, wherein the glass cloth has a cover factor of 1000 or more.

Description

[Technical Field]

[0001] This invention relates to a sheet. [Background technology]

[0002] Traditionally, in building structures, the law stipulates that the main structural elements such as columns, beams, floors, roofs, and walls must be made of fire-resistant material in order to protect the building from fire.

[0003] One method for creating a fire-resistant structure is to attach a heat-expandable fire-resistant sheet to the parts of the main structure and other areas that require fire resistance, using an adhesive.

[0004] As an example of the aforementioned heat-expandable fire-resistant sheet, Patent Document 1 proposes a heat-expandable fire-resistant sheet composed of a fibrous sheet and a heat-expandable fire-resistant material, wherein the fibrous sheet contains inorganic fibers, and the inorganic fibers are arranged in a mesh-like structure. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-92256 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The inventors of this invention have found that the heat-expandable fire-resistant sheet described in Patent Document 1 has a problem in that the heat-expandable fire-resistant sheet is prone to deformation when the heat-expandable fire-resistant material expands. Furthermore, they have found that when the heat-expandable fire-resistant sheet deforms, parts that should be given fire resistance, such as the main structure, become exposed, and the fire resistance of the main structure may be inferior.

[0007] The present invention aims to solve the above-mentioned conventional problems and to provide a sheet that can suppress deformation of the sheet when the heat-expandable fire-resistant coating layer expands.

Means for Solving the Problem

[0008] As a result of the inventor's study, it was found that the heat-expandable refractory sheet described in Patent Document 1 has a mesh structure in which inorganic fibers are arranged at intervals of 2 mm to 30 mm, so that the rigidity of the fibrous sheet is inferior, and thus deformation is likely to occur when the heat-expandable refractory material foams. As a result of further intensive study by the inventor, it was found that by using a glass cloth having a cover factor of 1000 or more, deformation of the sheet can be effectively suppressed when the heat-expandable refractory coating layer foams. The present invention has been completed by further study based on such findings.

[0009] That is, the present invention provides an invention in the following aspects. <1> A sheet having a glass cloth and a heat-expandable refractory coating layer laminated on the glass cloth, wherein the glass cloth has a cover factor of 1000 or more. <2> The sheet according to <1>, wherein the heat-expandable refractory coating layer is laminated on the glass cloth without an adhesive layer. <3> The sheet according to <1>, wherein the heat-expandable refractory coating layer is laminated on the glass cloth without an adhesive layer, and a part of the heat-expandable refractory coating layer is laminated in a state of biting into the weave of the glass cloth. <4> The sheet according to any one of <1> to <3>, wherein no other layer is laminated on the surface of the heat-expandable refractory coating layer opposite to the surface on which the glass cloth is laminated. <5> The ratio (mass of heat-expandable refractory coating layer / mass of glass cloth) of the mass (g / m 2 ) of the glass cloth to the mass (g / m 2 ) of the heat-expandable refractory coating layer is 0.5 to 3.5. The sheet according to any one of <1> to <4>. <6> The aforementioned heat-expandable fire-resistant coating layer comprises a resin, a foaming agent, and a carbonizing agent. <1> ~ <5> The sheet listed in one of the following. <7> The aforementioned resin is an ethylene-vinyl acetate copolymer. <6> The sheet described above. <8> The foaming agent is one or more selected from the group consisting of melamine and its derivatives, ammonium polyphosphate, and ammonium phosphate. <6> or <7> The sheet described above. <9> The carbonizing agent is a polyhydric alcohol. <6> ~ <8> The sheet listed in one of the following. <10> The aforementioned polyhydric alcohol is at least one selected from the group consisting of pentaerythritol, dipentaerythritol, and tripentaerythritol. <9> The sheet described above. <11> Used in battery packs that house battery packs in which multiple battery cells are connected in series or parallel, <1> ~ <10> The sheet listed in one of the following. <12> A battery pack containing a battery pack in which multiple battery cells are connected in series or parallel, <1> ~ <10> A battery pack equipped with a sheet as described in one of the following. <13> As a component of a battery pack that houses a battery pack in which multiple battery cells are connected in series or parallel <1> ~ <10> A method for suppressing thermal runaway in a battery pack, comprising using a sheet described in any of the above, wherein when the battery cell ignites, the heat-expandable fire-resistant coating layer of the sheet expands, thereby preventing the overheating from spreading to other battery cells adjacent to the ignited battery cell. [Effects of the Invention]

[0010] The sheet of the present invention can effectively suppress deformation of the sheet when the heat-expandable fire-resistant coating layer expands. [Brief explanation of the drawing]

[0011] [Figure 1]This is a photograph showing the state of the sheet sample from Example 1 after the heating test. [Figure 2] This is a photograph showing the state of the sheet sample from Example 2 after the heating test. [Modes for carrying out the invention]

[0012] The sheet of the present invention is a sheet having a glass cloth and a heat-expandable fire-resistant coating layer laminated on the glass cloth, wherein the glass cloth has a cover factor of 1000 or more. The sheet of the present invention will be described in detail below.

[0013] <glass cloth> The sheet of the present invention comprises glass cloth. In the sheet of the present invention, the glass cloth primarily serves to enhance the fire resistance of the sheet and to act as a base material for fixing the heat-expandable fire-resistant coating layer described later.

[0014] Glass cloth is made up of glass yarn for both the warp and weft threads.

[0015] The glass material constituting the glass yarn is not particularly limited, and known glass materials can be used. Specific examples of glass materials include alkali-free glass (E glass), acid-resistant alkali-containing glass (C glass), high-strength, high-modulus glass (S glass, T glass, etc.), and alkali-resistant glass (AR glass).

[0016] The yarn count of the glass yarn is not particularly limited as long as the cover factor described later is satisfied. The yarn count of the glass yarn is preferably 20 to 140 tex, more preferably 60 to 140 tex. In the present invention, the yarn counts of the warp and weft threads in the glass cloth are values ​​measured and calculated according to the method specified in "7.1 Yarn Count" of the Japanese Industrial Standard JIS R 3420:2013 (General Test Methods for Glass Fibers).

[0017] The average diameter of the glass single fibers constituting the glass yarn is not particularly limited as long as the coverage factor described later is satisfied, but for example, it is 6 to 10 μm, preferably 8.5 to 10 μm. The number of glass single fibers constituting the glass yarn is also not particularly limited as long as the coverage factor described later is satisfied, but for example, it is 150 to 1000, preferably 350 to 900. Here, the average diameter and number of glass single fibers are measured and calculated as follows. Two pieces of glass cloth to be measured are cut to 30 cm square, one for warp observation and the other for weft observation, and each is embedded in epoxy cold embedding resin and hardened. Next, the glass cloth embedded in epoxy cold embedding resin is polished to the extent that the warp or weft is observable, and the average diameter is observed and measured using an SEM at a magnification of 1000x, and the number of fibers at a magnification of 500x. (1) Average diameter of glass single fiber (μm) For both the warp and weft threads, 30 strands are randomly selected. The diameter of the cross-section (the largest portion) of all the glass fibers in these 30 warp and weft threads is measured, and the arithmetic mean is calculated to determine the average diameter of the glass fibers in the warp and weft threads. (2) Number of bottles (bottles) Thirty warp threads and 30 weft threads are randomly selected, the total number of glass filaments in these 30 warp and weft threads is measured, and the arithmetic mean is calculated to determine the number of glass filaments in the warp and weft threads.

[0018] In glass cloth, the weaving density of the warp and weft threads is not particularly limited, but for example, it is 20 threads / 25 mm or more and 100 threads / 25 mm or less, preferably 25 threads / 25 mm or more and 75 threads / 25 mm or less, and more preferably 30 threads / 25 mm or more and 50 threads / 25 mm or less. The weaving density of the warp threads in glass cloth may be the same as or different from the weaving density of the weft threads. In the present invention, the weaving density of the warp and weft threads is a value measured and calculated according to the method specified in "7.9 Density (weaving density)" of the Japanese Industrial Standard JIS R 3420:2013 (General Test Methods for Glass Fibers).

[0019] The glass cloth has a cover factor of 1000 or more. By using a glass cloth having a cover factor of 1000 or more, it is possible to increase the rigidity of the sheet and suppress deformation of the sheet when the heat-expandable refractory coating layer foams during heating. In the present invention, the cover factor is a value calculated by the following formula (I). CF = (Dw) 1 / 2 ×W + (Df) 1 / 2 ×F (I) In the above formula, the abbreviations represent the following. Dw: The count of warp yarns (dtex) Df: The count of weft yarns (dtex) W: Warp yarn density (threads / 25 mm) F: Weft yarn density (threads / 25 mm)

[0020] The cover factor is preferably 1000 to 4000, more preferably 1300 to 3500, still more preferably 1500 to 3000, even more preferably 1700 to 2500, yet more preferably 1850 to 2500, and particularly preferably 2000 to 2500.

[0021] The thickness of the glass cloth is, for example, 80 to 450 μm, preferably 110 to 400 μm, more preferably 140 to 350 μm, still more preferably 150 to 330 μm, and even more preferably 170 to 310 μm. In the present invention, the thickness of the glass cloth is measured using an electronic micrometer with a minimum display value of 0.001 mm in accordance with Method B specified in "7.10.1 Thickness of Cloth" of Japanese Industrial Standard JIS R 3420:2013 (General Test Methods for Glass Fibers).

[0022] The mass of the glass cloth is, for example, 80 to 500 g / m 2 and preferably 130 to 450 g / m 2 , more preferably 180 to 400 g / m 2 , still more preferably 180 to 380 g / m 2 , even more preferably 200 to 380 g / m 2In this invention, the mass of the glass cloth is measured in accordance with the method specified in "7.2 Mass of cloth and mat (mass)" of the Japanese Industrial Standard JIS R 3420:2013 (General Test Methods for Glass Fibers).

[0023] <Heat-expandable fire-resistant coating layer> The sheet of the present invention has a heat-expandable fire-resistant coating layer. In the sheet of the present invention, the heat-expandable fire-resistant coating layer expands when the ambient temperature reaches a predetermined temperature due to a fire or the like, forming an insulating layer.

[0024] Examples of heat-expandable compositions used as materials for forming a heat-expandable fire-resistant coating layer include those containing a resin, a foaming agent, and a carbonizing agent.

[0025] Examples of resins included in the heat-expandable composition include polyethylene resins, polypropylene resins, polybutene resins, polypentene resins, polystyrene resins, polycarbonate resins, acrylic resins, polyphenylene ether resins, polyamide resins, polyvinyl chloride resins, phenolic resins, polyurethane resins, chloroprene resins, petroleum resins, polybutadiene, polyisobutylene, nitrile rubber, butyl rubber, vinyltoluene-butadiene copolymer, vinyltoluene-acrylic acid ester copolymer, vinyltoluene-methacrylate ester copolymer, styrene-butadiene copolymer, ethylene-methacrylate ester copolymer, and ethylene-vinyl acetate copolymer. These may be used individually or in combination of two or more. Of these, in the sheet manufacturing method of the present invention described later, ethylene-vinyl acetate copolymer is preferred from the viewpoint of facilitating the lamination of a heat-expandable fire-resistant coating layer onto glass cloth by extrusion molding using pellets made of the heat-expandable composition.

[0026] In the heat-expandable fire-resistant coating layer, the content of the resin is, for example, 15 to 40% by mass, preferably 25 to 35% by mass.

[0027] Examples of foaming agents included in the heat-foaming composition include melamine and its derivatives (e.g., melamine formaldehyde, methylolated melamine, hexamethoxymethylmelamine, melamine monophosphate, melamine diphosphate, melamine polyphosphate phosphate, melamine pyrophosphate, and melamine cyanurate), dicyandiamide and its derivatives, azodicarbonamide, urea, thiourea, ammonium polyphosphate, and ammonium phosphate. These may be used individually or in combination of two or more. Of these, one or more selected from the group consisting of melamine and its derivatives, ammonium polyphosphate, and ammonium phosphate are preferred.

[0028] In the heat-expandable fire-resistant coating layer, the content of the foaming agent is, for example, 30 to 60% by mass, preferably 35 to 55% by mass, and more preferably 40 to 50% by mass.

[0029] Examples of carbonizing agents included in the heat-expanding composition include polyhydric alcohols, polysaccharides, and oligosaccharides. Examples of polyhydric alcohols include pentaerythritol, dipentaerythritol, and tripentaerythritol. Examples of polysaccharides include starch and cellulose. Examples of oligosaccharides include glucose and fructose. These may be used individually or in combination of two or more. Of these, polyhydric alcohols are preferred, and more preferably at least one selected from the group consisting of pentaerythritol, dipentaerythritol, and tripentaerythritol.

[0030] In the heat-expandable refractory coating layer, the content of the carbonizing agent is, for example, 5 to 25% by mass, and preferably 5 to 15% by mass.

[0031] The heat-expandable composition may contain components other than resins, foaming agents, and carbonizing agents. These other components may include fillers such as silicates like talc, carbonates such as calcium carbonate and sodium carbonate, metal oxides such as titanium dioxide, aluminum oxide, and zinc oxide, and natural minerals such as clay, volcanic ash, and mica; fibers such as organic fibers (e.g., pulp fibers, polyester fibers, polypropylene fibers, aramid fibers, vinylon fibers, polyethylene fibers, polyarylate fibers, PBO fibers, nylon fibers, acrylic fibers, vinyl chloride fibers, cellulose fibers, etc.) and inorganic fibers (e.g., glass fibers, rock wool, silica fibers, silica-alumina fibers, carbon fibers, silicon carbide fibers, etc.); and additives such as flame retardants, pigments, thickeners, dispersants, preservatives, and antifungal agents. These may be used individually or in combination of two or more. Of these, fillers and fibers (preferably inorganic fibers) are preferred. When a filler is included, the filler content in the heat-expandable fire-resistant coating layer is, for example, 5 to 25% by mass, preferably 5 to 15% by mass. When fibers are included, the fiber content in the heat-expandable fire-resistant coating layer is, for example, 0.5 to 10% by mass, preferably 1 to 5% by mass. Additives are selected within a range that does not significantly affect the heat-expandable fire-resistant coating layer, and the additive content in the heat-expandable fire-resistant coating layer is, for example, 0.1 to 5% by mass, preferably 0.5 to 3% by mass.

[0032] The mass of the heat-expandable fire-resistant coating layer is, for example, 50 to 500 g / m². 2 The amount is preferably 80-500 g / m². 2 , comfortable 200~500g / m 2 More preferably 280-450 g / m² 2 , more preferably 300-450 g / m 2 That is the case.

[0033] The thickness of the heat-expandable fire-resistant coating layer is, for example, 15 to 310 μm, preferably 35 to 310 μm, more preferably 125 to 310 μm, even more preferably 150 to 290 μm, and even more preferably 170 to 270 μm.

[0034] <Sheet structure, etc.> The sheet of the present invention is formed by laminating the glass cloth and the heat-expandable fire-resistant coating layer. In the sheet of the present invention, the heat-expandable fire-resistant coating layer may be laminated to the glass cloth without an adhesive layer, or it may be laminated to the glass cloth via an adhesive layer. However, when the heat-expandable fire-resistant coating layer is laminated to the glass cloth via an adhesive layer, the adhesive layer tends to burn when heated, causing the glass cloth and the heat-expandable fire-resistant coating layer to separate easily, resulting in insufficient fixation of the heat-expandable fire-resistant coating layer by the glass cloth, and making it difficult to effectively suppress deformation of the sheet when the heat-expandable fire-resistant coating layer expands. For this reason, it is preferable that the heat-expandable fire-resistant coating layer is laminated to the glass cloth without an adhesive layer.

[0035] Furthermore, in the sheet of the present invention, it is preferable that the heat-expandable fire-resistant coating layer is laminated to the glass cloth without an adhesive layer, and that a portion of the heat-expandable fire-resistant coating layer is embedded in the weave of the glass cloth. In other words, it is preferable that the heat-expandable composition, which is the material for forming the heat-expandable fire-resistant coating layer, hardens while embedded in the weave of the glass cloth, so that a portion of the heat-expandable fire-resistant coating layer is formed between the weave of the glass cloth. With the sheet of the present invention having this structure, when the heat-expandable fire-resistant coating layer expands, the heat-expandable fire-resistant coating layer is sufficiently fixed by the glass cloth, and coupled with the fact that the glass cloth has the aforementioned cover factor, deformation of the sheet can be suppressed more effectively.

[0036] Furthermore, it is preferable that the sheet of the present invention does not have any other layers laminated on the surface opposite to the surface on which the glass cloth of the heat-expandable fire-resistant coating layer is laminated. Having this structure in the sheet of the present invention makes it easier to suppress deformation of the sheet caused by thermal shrinkage of other layers during heating.

[0037] The mass of the sheet of the present invention is, for example, 300 to 900 g / m². 2 The amount is preferably 400-800 g / m².2 , more preferably 480-800 g / m² 2 More preferably 580-800 g / m² 2 , more preferably 600-750 g / m² 2 Particularly preferred is 600-700 g / m² 2 That is the case.

[0038] In the sheet of the present invention, the mass of the glass cloth (g / m²) 2 ) and the mass (g / m²) of the heat-expandable fire-resistant coating layer 2 The ratio (mass of heat-expandable fire-resistant coating layer / mass of glass cloth) is, for example, 0.3 to 4, preferably 0.5 to 3.5, more preferably 0.7 to 2.5, even more preferably 0.8 to 2.5, and particularly preferably 1.8 to 2.3.

[0039] <Method of manufacturing the sheet>

[0040] The method for manufacturing the sheet of the present invention is not particularly limited, but a preferred example is a manufacturing method that includes the following steps. (Step 1) A step to prepare pellets of a heat-expandable composition and glass cloth, which are materials for forming a heat-expandable fire-resistant coating layer. (Step 2) A step in which the pellets are melted and the molten heat-expandable composition is extruded onto the glass cloth by an extrusion molding method so that the heat-expandable composition becomes a sheet, thereby laminating a heat-expandable fire-resistant coating layer onto the glass cloth.

[0041] Step 2, for example, involves extruding molten pellets onto glass cloth using a T-die. In this method, the extruded heat-expandable composition is in a molten state and sheet-like form onto the glass cloth. The molten heat-expandable composition and the glass cloth are then pressed together by passing them through a roll, and cooled to integrate them. This method allows the heat-expandable fire-resistant coating layer to be laminated onto the glass cloth with a portion of the heat-expandable fire-resistant coating layer embedded in the weave of the glass cloth.

[0042] <Uses of the sheet> The sheet of the present invention is not particularly limited in its use, but is preferably used, for example, as a covering material for major structural elements such as columns, beams, floors, roofs, and walls to protect buildings from fire, and as a battery pack (secondary battery housing) that houses a battery pack in which multiple battery cells are connected in series or parallel. Examples of such battery packs include lithium-ion secondary batteries. In such battery packs, when an abnormality occurs in some battery cells, the battery cells may overheat and ignite, and the overheating may propagate to adjacent battery cells; this phenomenon is called thermal runaway. When thermal runaway occurs in a battery cell, the flammable electrolyte burns, and components of the battery cell such as electrodes and battery containers may melt and ignite, potentially causing high-temperature blasts to violently eject from individual battery cells.

[0043] In a battery pack equipped with the above-described battery pack, if one battery cell experiences thermal runaway, there is a high probability that adjacent battery cells will also experience thermal runaway, potentially leading to a major accident. Therefore, it is preferable to use the sheet of the present invention to suppress thermal runaway. Examples of how the sheet of the present invention can be provided in the battery pack include providing the sheet between adjacent battery cells and providing it to cover the inner wall of the battery pack's cover material. In such configurations, in a battery pack containing a battery pack in which multiple battery cells are connected in series or parallel, if a battery cell ignites, the heat-expandable fire-resistant coating layer of the sheet of the present invention will expand, increasing its heat insulation and preventing the overheating from spreading to other battery cells adjacent to the ignited battery cell. [Examples]

[0044] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0045] Example 1 As the glass cloth, we prepared "H201MC 107F," a product of Unitika Ltd.'s E-glass cloth brand name. This glass cloth consists of warp and weft threads of G75 1 / 0 1Z (average diameter of glass single fibers 9 μm, number of single fibers 400, count 67.5 tex), with a warp density of 42 threads / 25 mm, a weft density of 31 threads / 25 mm, a cover factor of 1897, and a mass of 208 g / m². 2 The thickness was 180 μm.

[0046] A heat-expandable composition was prepared to have the following composition 1, and then melt-kneaded to form pellets. <Composition 1> (Synthetic resin) Ethylene-vinyl acetate copolymer: 29.0% by mass (Foaming agent) Ammonium phosphate: 46.0% by mass (Carbonizing agent) Pentaerythritol: 11.0% by mass (Other ingredients) Titanium dioxide: 11.0% by mass Glass fiber: 2.0% by mass Additive (dispersant): 1.0% by mass Total 100.0% by mass

[0047] The prepared pellets are melted and transferred from the T-die onto the glass cloth in a molten, sheet-like state, resulting in a heat-expandable fire-resistant coating layer with a mass of 309 g / m². 2 The mixture was extruded in this manner, and the molten heat-expandable composition and the glass cloth were passed through a roll and pressed together, then cooled to integrate them and obtain a sheet. In this sheet, a portion of the heat-expandable fire-resistant coating layer was laminated in a state where it was embedded in the weave of the glass cloth. The mass of this sheet was 517 g / m². 2 That was the case.

[0048] Example 2 The mass of the heat-expandable fire-resistant coating layer is 421 g / m². 2 A sheet was obtained in the same manner as in Example 1, except that it was extruded in the manner described above. In this sheet, a portion of the heat-expandable fire-resistant coating layer was laminated in a state where it was embedded in the weave of the glass cloth. The mass of this sheet was 629 g / m². 2 That was the case.

[0049] Example 3 For the glass cloth, we prepared "H155MC110F," a product of Unitika Ltd.'s E-glass cloth brand. This glass cloth has warp and weft threads of G75 1 / 0 1Z (average diameter of glass single fibers 9 μm, number of single fibers 400, count 67.5 tex), a warp density of 31 threads / 25 mm, a weft density of 25 threads / 25 mm, a cover factor of 1455, and a mass of 158 g / m². 2 The thickness was 150 μm.

[0050] The pellets prepared in Example 1 were melted and transferred from the T-die onto the glass cloth in a molten, sheet-like state, with a heat-expandable refractory coating layer having a mass of 311 g / m². 2 The mixture was extruded in this manner, and the molten heat-expandable composition and the glass cloth were passed through a roll and pressed together. It was then cooled to integrate them, resulting in a sheet. In this sheet, a portion of the heat-expandable fire-resistant coating layer was laminated in a state where it was embedded in the weave of the glass cloth. The mass of this sheet was 469 g / m². 2 That was the case.

[0051] Example 4 For the glass cloth, we prepared "H350MJ90CH," a product of Unitika Ltd.'s E-glass cloth brand. This glass cloth has warp and weft threads of G37 1 / 0 1Z (average diameter of glass single fibers 9 μm, number of single fibers 800, count 135 tex), a warp density of 33 threads / 25 mm, a weft density of 30 threads / 25 mm, a cover factor of 2315, and a mass of 375 g / m². 2 The thickness was 300 μm.

[0052] The pellets prepared in Example 1 were melted and transferred from the T-die onto the glass cloth in a molten, sheet-like state, with a heat-expandable refractory coating layer having a mass of 322 g / m². 2 The mixture was extruded in this manner, and the molten heat-expandable composition and the glass cloth were passed through a roll and pressed together. It was then cooled to integrate them, resulting in a sheet. In this sheet, a portion of the heat-expandable fire-resistant coating layer was laminated in a state where it was embedded in the weave of the glass cloth. The mass of this sheet was 697 g / m².2 That was the case.

[0053] Example 5 As the glass cloth, we prepared E-glass cloth product name "H105MZ107F" manufactured by Unitika Ltd. This glass cloth has warp and weft threads of E225 1 / 0 1Z (average diameter of glass single fiber 7 μm, number of single fibers 200, count 22.5 tex), warp density of 60 threads / 25 mm, weft density of 57 threads / 25 mm, cover factor of 1755, and mass of 109 g / m 2 The thickness was 95 μm.

[0054] The pellets prepared in Example 1 were melted and transferred from the T-die onto the glass cloth in a molten, sheet-like state, with a heat-expandable refractory coating layer having a mass of 315 g / m². 2 The mixture was extruded in this manner, and the molten heat-expandable composition and the glass cloth were passed through a roll and pressed together. It was then cooled to integrate them, resulting in a sheet. In this sheet, a portion of the heat-expandable fire-resistant coating layer was laminated in a state where it was embedded in the weave of the glass cloth. The mass of this sheet was 424 g / m². 2 That was the case.

[0055] Comparative Example 1 For the glass cloth, we prepared "M85F104," an E-glass cloth manufactured by Unitika Ltd. This glass cloth has the following specifications: warp and weft threads are G75 1 / 0 1Z (average diameter of glass single fibers 9 μm, number of single fibers 400, count 67.5 tex), warp density is 16 threads / 25 mm, weft density is 15 threads / 25 mm, cover factor is 805, and mass is 84 g / m². 2 The thickness was 100 μm.

[0056] The pellets prepared in Example 1 were melted and transferred from the T-die onto the glass cloth in a molten, sheet-like state, with a heat-expandable refractory coating layer having a mass of 299 g / m². 2The material was extruded in this manner, and the molten heat-expandable composition and the glass cloth were passed through a roll and pressed together, then cooled to integrate them and obtain a sheet. In this sheet, a portion of the heat-expandable fire-resistant coating layer was laminated in a state where it was embedded in the weave of the glass cloth. The mass of this sheet was 383 g / m². 2 That was the case.

[0057] (evaluation) The sheets from Examples 1-5 and Comparative Example 1 were cut into 10cm squares to obtain measurement samples. These samples were placed in a muffle furnace and heated at 500°C for 1 hour while resting on the hearth. After that, the samples were removed, placed on a flat table to cool to room temperature, and the curvature height of the four sides of the samples was measured. The maximum value of the curvature height of the four sides was determined as the curvature and evaluated according to the following criteria. A score of "C" or higher was considered acceptable. The evaluation results are shown in Table 1, and a photograph of the sample from Example 1 after heating is shown in Figure 1, and a photograph of the sample from Example 2 after heating is shown in Figure 2. <Evaluation Criteria> A: Curvature of 5mm or less B: Curvature exceeds 5mm but is less than or equal to 10mm C: Warp exceeding 10mm but not exceeding 20mm D: Warping exceeds 20 mm, or the heat-expandable fire-resistant coating layer and the glass cloth are separated.

[0058] [Table 1]

[0059] The sheets of Examples 1 to 5 are sheets having a glass cloth and a heat-expandable fire-resistant coating layer laminated to the glass cloth without an adhesive layer in between. A portion of the heat-expandable fire-resistant coating layer is embedded in the weave of the glass cloth, and the cover factor of the glass cloth is 1000 or more. As a result, deformation of the sheet can be effectively suppressed when the heat-expandable fire-resistant coating layer expands.

[0060] In particular, the sheets of Examples 1, 2 and 4 have a glass cloth cover factor in the range of 1500 to 3000, and the mass of the glass cloth (g / m²) is within the range of 1500 to 3000. 2 ) and the mass (g / m²) of the heat-expandable fire-resistant coating layer 2 The ratio (mass of heat-expandable fire-resistant coating layer / mass of glass cloth) was in the range of 0.7 to 2.5, indicating that deformation of the sheet was more effectively suppressed when the heat-expandable fire-resistant coating layer expanded. Furthermore, comparing Examples 1 and 2, Example 2 had a larger mass of glass cloth (g / m²). 2 ) and the mass (g / m²) of the heat-expandable fire-resistant coating layer 2 The ratio (mass of heat-expandable fire-resistant coating layer / mass of glass cloth) was within the range of 1.8 to 2.3, indicating that the deformation of the sheet was more effectively suppressed when the heat-expandable fire-resistant coating layer expanded.

[0061] On the other hand, in Comparative Example 1, the glass cloth cover factor was less than 1000, resulting in warping exceeding 20 mm and separation between the heat-expandable fire-resistant coating layer and the glass cloth.

Claims

1. A sheet comprising a glass cloth and a heat-expandable fire-resistant coating layer laminated on the glass cloth, The aforementioned glass cloth is a sheet having a cover factor of 1000 or more.

2. The sheet according to claim 1, wherein the heat-expandable fire-resistant coating layer is laminated to the glass cloth without an adhesive layer in between.

3. The sheet according to claim 1, wherein the heat-expandable fire-resistant coating layer is laminated onto the glass cloth without an adhesive layer, and a portion of the heat-expandable fire-resistant coating layer is laminated in such a state that it is embedded in the weave of the glass cloth.

4. The sheet according to claim 1, wherein no other layer is laminated on the surface of the heat-expandable fire-resistant coating layer opposite to the surface on which the glass cloth is laminated.

5. The mass of the glass cloth (g / m 2 ) and the mass (g / m²) of the heat-expandable fire-resistant coating layer 2 The sheet according to claim 1, wherein the ratio (mass of heat-expandable fire-resistant coating layer / mass of glass cloth) is 0.5 to 3.

5.

6. The sheet according to claim 1, wherein the heat-expandable fire-resistant coating layer comprises a resin, a foaming agent, and a carbonizing agent.

7. The sheet according to claim 6, wherein the resin is an ethylene-vinyl acetate copolymer.

8. The sheet according to claim 6, wherein the foaming agent is one or more selected from the group consisting of melamine and its derivatives, ammonium polyphosphate, and ammonium phosphate.

9. The sheet according to claim 6, wherein the carbonizing agent is a polyhydric alcohol.

10. The sheet according to claim 9, wherein the polyhydric alcohol is at least one selected from the group consisting of pentaerythritol, dipentaerythritol, and tripentaerythritol.

11. A sheet according to any one of claims 1 to 10, used in a battery pack that houses a battery pack in which multiple battery cells are connected in series or in parallel.

12. A battery pack for housing a battery pack in which multiple battery cells are connected in series or in parallel, comprising the sheet described in any one of claims 1 to 10.

13. A method for suppressing thermal runaway in a battery pack, wherein a sheet described in any one of claims 1 to 10 is used as a component of a battery pack containing a battery pack in which multiple battery cells are connected in series or parallel, and when a battery cell ignites, the heat-expandable fire-resistant coating layer of the sheet expands, thereby preventing overheating from spreading to other battery cells adjacent to the ignited battery cell.

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