Fire-spread prevention sheet and fire-spread prevention cover

Abstract

Provided is a fire-spread prevention sheet capable of preventing the spread of fire in products such as a product comprising a lithium-ion battery.　This fire-spread prevention sheet comprises: an inorganic fiber-molded body having a softening point temperature of 1000°C or more and a thermal conductivity of 0.5 W / m･K or less at 1000°C; and an inorganic fiber woven fabric covering the entirety of the inorganic fiber-molded body. The inorganic fiber woven fabric preferably comprise glass fibers, and the basis weight thereof is preferably 100 g / m2 or more.

Description

Fire prevention sheets and covers

[0001] The present invention relates to a fire prevention sheet suitable for preventing the spread of fire, particularly fires that break out in products equipped with lithium ion batteries, and a fire prevention cover using the same.

[0002] In recent years, efforts to prevent global warming have promoted the use of natural energy sources, such as solar power, instead of fossil fuels like petroleum. In particular, there is a global demand for electric vehicles, and many electric vehicles are being manufactured and sold. Lithium-ion batteries are commonly used in electric vehicles, and it is known that such batteries can experience thermal runaway if the separator separating the battery's positive and negative electrodes becomes overheated and melts during a fire. It is difficult to extinguish a battery experiencing thermal runaway, and once thermal runaway occurs, the thermal runaway can spread in a chain reaction, leading to thermal diffusion. Therefore, technologies have been developed to insert insulating material between electric vehicle battery cells to suppress thermal runaway between cells, and to incorporate flame-retardant materials into battery modules to protect drivers and passengers from thermal runaway (see, for example, Patent Document 1 below).

[0003] Automobiles are mainly imported and exported by ship, but recently, there have been confirmed cases of fires breaking out on car carriers. When transporting electric vehicles equipped with lithium-ion batteries, as mentioned above, the lithium-ion batteries can go into thermal runaway, which not only takes a long time to extinguish, but can also spread to many cars, damaging the carrier itself and potentially killing the crew.

[0004] On the other hand, lithium-ion batteries are becoming increasingly commonplace, being used in electronic devices such as personal computers and as storage batteries in homes equipped with solar power generation facilities. As lithium-ion batteries are increasingly being used in homes, there has been concern that these batteries could ignite and experience thermal runaway, potentially causing a major house fire. To prevent the spread of fire in the event of a lithium-ion battery fire, inorganic fiber sheets that can be used as fire-resistant heat-resistant materials for storage batteries (see Patent Document 2 below) and flame-resistant fiber sheets that can be used to prevent the spread of fire in various electrical appliances (see Patent Document 3 below) have been developed.

[0005] International Publication No. 2019 / 044801 Japanese Patent Application Laid-Open No. 2020-122228 Japanese Patent Application Laid-Open No. 2023-130115

[0006] Lithium-ion battery packs are made up of multiple battery modules each consisting of a battery cell, and although there have been conventional insulation materials between the battery cells and flame retardants between the battery modules, no measures have been taken to prevent the fire from spreading to the surrounding area in the event of a fire breaking out in an entire product, such as an electric vehicle or storage battery, that uses lithium-ion batteries.When a lithium-ion battery pack ignites, the reaction inside the battery causes thermal runaway, which causes the fire to continue and become impossible to extinguish, leading to a large-scale fire.

[0007] In particular, when vehicles are loaded onto car carriers, they are spaced approximately 10 cm apart to maximize loading efficiency. Therefore, if a car fire occurs, the vehicles are so close together that the fire can easily ignite adjacent vehicles and spread, potentially resulting in a major fire. Furthermore, if a residential storage battery ignites and goes into thermal runaway, it could quickly spread to a home, causing a major fire and even taking lives. Minimizing fires on car carriers and in homes like these could enhance the safety of lithium-ion battery products.

[0008] Therefore, an object of the present invention is to provide a fire prevention sheet and a fire prevention cover using the same that have fire resistance and heat insulation properties against ignition of lithium ion batteries and can prevent the spread of fire to the surrounding area. This fire prevention cover can be placed on the target object in advance, but it can also be stored at all times and removed for use in the event of a fire.

[0009] The present invention has the following aspects.

[0010] [1] A fire spread prevention sheet comprising an inorganic fiber molded body having a softening point temperature of 1000°C or higher and a thermal conductivity at 1000°C of 0.5 W / m·K or lower, and an inorganic fiber woven fabric covering the entire body.

[0011] [2] The fire spread prevention sheet according to [1], wherein the inorganic fiber woven fabric is made of glass fiber.

[0012] [3] The inorganic fiber woven fabric has a basis weight of 100 g / m２ The fire spread prevention sheet according to [1] or [2], characterized in that:

[0013] [4] The fire spread prevention sheet according to any one of [1] to [3], wherein the inorganic fiber woven fabric is a fabric in which warp threads and weft threads are alternately crossed, and is a fabric to which no coating material is applied.

[0014] [5] The fire spread prevention sheet according to any one of [1] to [4], which has a covering material that covers at least a part of the edge of the inorganic fiber woven fabric.

[0015] [6] The fire spread prevention sheet according to any one of [1] to [3], wherein the inorganic fiber woven fabric is a fabric in which warp threads and weft threads are alternately crossed, and is a fabric to which a coating material is applied.

[0016] [7] The fire spread prevention sheet according to any one of [1] to [3], wherein the inorganic fiber woven fabric is a woven fabric in which at least one of the warp and weft threads crosses over or under at least two or more of the other threads.

[0017] [8] The fire spread prevention sheet according to any one of [1] to [7], wherein the inorganic fiber molded body is a needle blanket containing alumina / silica-based fibers.

[0018] [9] The inorganic fiber molded body has a basis weight of 300 g / m ２ The fire spread prevention sheet according to any one of [1] to [8] above.

[0019]

[10] A fire spread prevention cover in which a plurality of fire spread prevention sheets according to any one of [1] to [9] are sewn together with thread, the thread having a first thread that is more durable at high temperatures than the inorganic fibers of the inorganic fiber woven fabric.

[0020]

[11] The fire spread prevention cover according to

[10] , wherein the threads include second threads that are more durable at room temperature than the first threads.

[0021]

[12] The fire spread prevention cover according to

[11] , wherein the first thread is located on the edge side of the fire spread prevention sheet, and the second thread is located inside the fire spread prevention sheet relative to the first thread and extends in parallel with the first thread.

[0022]

[13] A fire spread prevention cover according to any one of

[10] to

[12] , in which three or more of the fire spread prevention sheets are connected by seams formed with the thread, and the seams are alternately arranged on both sides of the fire spread prevention cover.

[0023]

[14] A fire spread prevention cover according to any one of

[10] to

[12] , in which three or more of the fire spread prevention sheets are connected by seams formed with the thread, and the seams are arranged on one side of the fire spread prevention cover.

[0024]

[15] The fire spread prevention cover according to any one of

[10] to

[14] , which is used to cover a product equipped with a lithium ion battery.

[0025] 1 is a diagram schematically showing a cross section of a fire spread prevention sheet according to one embodiment of the present invention; FIG. 2 is a diagram showing an example of a method for joining the periphery of the fire spread prevention sheet of FIG. 1; FIG. 3 is a partially enlarged perspective view showing an example of a fire spread prevention cover made using a fire spread prevention sheet in an unfolded state; FIG. 4 is a partially enlarged perspective view showing the fire spread prevention cover of FIG. 3 in a folded state; FIG. 5 is a partially enlarged perspective view showing another example of a fire spread prevention cover made using a fire spread prevention sheet in an unfolded state; FIG. 6 is a partially enlarged perspective view showing the fire spread prevention cover of FIG. 5 in a folded state; FIG. 7 is a graph showing the relationship between the number of cycles and weight change in an abrasion test for sheets of Examples 1 and 3 and Comparative Example 2; FIG. 8 is a micrograph of the surface of the coated plate of Example 1 in a damage test in the examples; FIG. 9 is a micrograph of the surface of the coated plate of Example 3 in a damage test in the examples; FIG. 10 is a micrograph of the surface of the coated plate of Example 4 in a damage test in the examples; FIG. 11 is a micrograph of the surface of the coated plate of Comparative Example 2 in a damage test in the examples; 1 is a graph showing the relationship between the immersion time and the water absorption weight of each glass fiber woven fabric in a water permeability test in Examples. 2 is a diagram for explaining a measurement method for a flexibility test in Examples. 3 is a graph showing the relationship between the deflection distance and the applied weight of each test sheet in a flexibility test in Examples.

[0026] An embodiment of the fire spread prevention sheet of the present invention will be described below, although the present invention is not limited to this embodiment.

[0027] (Fire spread prevention sheet) As shown in Figure 1, a fire spread prevention sheet 1 according to one embodiment of the present invention is characterized by comprising an inorganic fiber molded body 2 having a softening point temperature of 1000°C or higher and a thermal conductivity at 1000°C of 0.5 W / m·K or lower, and an inorganic fiber woven fabric 3 covering the entire body.

[0028] (Inorganic Fiber Molded Product) The inorganic fiber molded product 2 has a softening point temperature of 1000°C or higher, which provides heat resistance that can withstand high heat generated by a fire and can shield the flames. From this perspective, the softening point temperature of the inorganic fiber molded product 2 is more preferably 1050°C or higher, and particularly preferably 1100°C or higher. The softening point temperature of the inorganic fiber molded product 2 can be measured, for example, by penetration measurement using an alumina pin. Specifically, an alumina pin with an outer diameter of 1.0 mm and a length of 25 mm is embedded in the inorganic fiber molded product 2 to a depth of 5 mm, and the temperature is raised to a predetermined temperature at a rate of 6°C / min while applying a load of 0.2 MPa. The predetermined temperature is determined as the softening point temperature when the height displacement of the alumina pin after maintaining that temperature for 1 hour is 20%.

[0029] The inorganic fiber molded body 2 has a thermal conductivity of 0.5 W / m·K or less at 1000°C, which not only provides high heat resistance but also excellent heat insulation so as to prevent excessive heat from being transferred to the surrounding area. From this perspective, the thermal conductivity of the inorganic fiber molded body 2 at 1000°C is more preferably 0.4 W / m·K or less, and particularly preferably 0.3 W / m·K or less. The thermal conductivity of the inorganic fiber molded body 2 at 1000°C can be measured, for example, by a transient hot wire method.

[0030] <Weight per unit area of ​​inorganic fiber molded body> The weight per unit area of ​​the inorganic fiber molded body 2 is set to 300 g / m ２ More than 600 g / m ２By increasing the basis weight to a certain level or more, the tensile strength is increased, the material can withstand the pressure and particles of gas that are emitted when a lithium-ion battery ignites, and the heat insulating performance is also improved. The upper limit of the basis weight is not particularly limited, but is preferably 1500 g / m ２ The following are preferable. As the basis weight increases, the weight of the sheet or cover increases, and the effort required for installation and removal increases. Therefore, the basis weight can be determined appropriately taking into consideration the ease of installation and removal.

[0031] <Shape of inorganic fiber molded body> The inorganic fiber molded body 2 is preferably in the form of a sheet having a predetermined thickness, although it is not particularly limited thereto. The thickness tends to increase as the basis weight increases. The planar shape of the inorganic fiber molded body 2 is not particularly limited thereto, and various shapes such as a square or a circle can be used.

[0032] <Material of Inorganic Fiber Molded Body> The inorganic fibers used for the inorganic fiber molded body 2 are not particularly limited, and examples thereof include single or composite fibers such as silica, alumina / silica, and zirconia, spinel, and titania containing these. Among these, alumina / silica-based fibers are preferred, and crystalline alumina / silica-based fibers are particularly preferred. The alumina / silica composition ratio (mass ratio) of the alumina / silica-based fibers is preferably in the range of 60 / 40 to 95 / 5, more preferably in the range of 70 / 30 to 84 / 16, and particularly preferably in the range of 70 / 30 to 76 / 24. Examples of the inorganic fiber molded body 2 include a needle blanket made of alumina / silica-based fibers that has heat insulating properties and does not contain a binder that burns when exposed to high temperatures.

[0033] <Average fiber diameter> The average fiber diameter of the inorganic fibers is preferably 3 μm to 10 μm, and more preferably 5 μm to 8 μm. The average fiber diameter is the average value of 100 fibers measured by observation with a microscope. If the average fiber diameter of the inorganic fibers is within the above range, even if the fire spread prevention sheet is damaged in the event of a fire and fiber dust is scattered, there is a low risk of it entering the alveoli of surrounding people, and there is no need to worry about health damage, which is preferable.

[0034] <Method for manufacturing inorganic fiber molded body> The inorganic fiber molded body 2 can be manufactured by a method including a step of obtaining a mat-like aggregate of inorganic fiber precursors by a sol-gel method, a step of subjecting the obtained mat-like aggregate of inorganic fiber precursors to a needling treatment, and a firing step of firing the needling-treated mat-like aggregate of inorganic fiber precursors to form an inorganic fiber molded body. However, the inorganic fiber molded body may also be manufactured by a method other than this.

[0035] Below, an example of a method for manufacturing the inorganic fiber molded body 2 will be explained using a method for manufacturing an alumina / silica-based fiber molded body as an example, but the inorganic fiber molded body of the present invention is not limited to an alumina / silica-based fiber molded body and, as mentioned above, may be a molded body made of silica, zirconia, spinel, titania, or a composite fiber thereof.

[0036] <<Spinning Step>> To produce a mat-like aggregate of alumina / silica-based fibers by the sol-gel method, first, a spinning solution containing basic aluminum chloride, a silicon compound, an organic polymer as a thickener, and water is spun by a blowing method to obtain an aggregate of alumina / silica fiber precursors.

[0037] <<Preparation of spinning solution>> Basic aluminum chloride; Al(OH) ３－ｘ Cl ｘ can be prepared, for example, by dissolving metallic aluminum in an aqueous solution of hydrochloric acid or aluminum chloride. The value of x in the above chemical formula is typically 0.45 to 0.54, preferably 0.5 to 0.53. Silica sol is preferably used as the silicon compound, but other water-soluble silicon compounds such as tetraethyl silicate and water-soluble siloxane derivatives can also be used. Suitable organic polymers include water-soluble polymers such as polyvinyl alcohol, polyethylene glycol, and polyacrylamide. The degree of polymerization of these is typically 1,000 to 3,000.

[0038] The spinning solution contains aluminum from basic aluminum chloride and silicon from silicon compound in a ratio of Al ２ O ３ and SiO ２In terms of weight ratio, the aluminum concentration is usually 99:1 to 65:35, preferably 99:1 to 70:30, and the aluminum concentration is preferably 170 g / L to 210 g / L and the organic polymer concentration is preferably 20 g / L to 50 g / L.

[0039] If the amount of silicon compound in the spinning solution is less than the above range, the alumina constituting the short fibers is likely to be converted to α-alumina, and the short fibers are likely to become embrittled due to the coarsening of alumina particles. On the other hand, if the amount of silicon compound in the spinning solution is more than the above range, mullite (3Al ２ O ３ 2SiO ２ ) and silica (SiO ２ ) increases and heat resistance tends to decrease.

[0040] When the aluminum concentration in the spinning solution is less than 170 g / L or the organic polymer concentration is less than 20 g / L, the spinning solution does not have an appropriate viscosity, resulting in a small fiber diameter for the resulting alumina / silica-based fibers. In other words, excessive free water in the spinning solution results in a slow drying rate during spinning by the blowing method, excessive stretching, and changes in the fiber diameter of the spun precursor fibers, preventing the production of short fibers with a predetermined average fiber diameter and a sharp fiber diameter distribution. Furthermore, when the aluminum concentration is less than 170 g / L, productivity decreases. On the other hand, when the aluminum concentration exceeds 210 g / L or the organic polymer concentration exceeds 50 g / L, the viscosity is too high to form a spinning solution. The preferred aluminum concentration in the spinning solution is 180 g / L to 200 g / L, and the preferred organic polymer concentration is 30 g / L to 40 g / L.

[0041] The spinning solution is prepared by dissolving the above Al in a basic aluminum chloride aqueous solution. ２ O ３ : SiO ２ The silicon compound and the organic polymer are added in proportion to each other, and the aluminum and organic polymer are concentrated so that their concentrations fall within the above-mentioned ranges.

[0042] <<Blowing>> Spinning (conversion of the spinning solution into fibers) is usually carried out by a blowing method in which the spinning solution is supplied into a high-speed spinning airflow, thereby obtaining an alumina short fiber precursor. The structure of the spinning nozzle used in the above spinning is not particularly limited, but a preferred structure is, for example, as described in Japanese Patent No. 2602460, in which the air flow blown out from the air nozzle and the spinning solution flow extruded from the spinning solution supply nozzle are parallel flows, and the parallel air flows are sufficiently rectified to contact the spinning solution.

[0043] In addition, during spinning, it is preferable that a sufficiently drawn fiber is first formed from the spinning solution under conditions in which evaporation of water and decomposition of the spinning solution are suppressed, and then the fiber is promptly dried. To achieve this, it is preferable to change the atmosphere from a state that suppresses evaporation of water to a state that promotes evaporation of water during the process from when the fiber is formed from the spinning solution to when it reaches the fiber collector.

[0044] The alumina / silica-based fiber precursor can be collected and accumulated using an accumulation device that has a structure in which an endless belt made of wire mesh is placed at approximately right angles to the spinning airflow, and the spinning airflow containing the alumina / silica-based fiber precursor is collided with the endless belt while the endless belt is rotating, and can be recovered as a continuous sheet-like accumulation (thin layer sheet) of the alumina / silica-based fiber precursor.

[0045] The basis weight of this thin sheet is preferably 10 g / m ２ ~200g / m ２ , particularly preferably 30 g / m ２ ~100g / m ２ To an extent, but not limited to this.

[0046] The thin sheets collected from the above-mentioned stacking device can be further stacked. Specifically, for example, a stack of inorganic fiber precursors (thin sheets) can be continuously drawn out and fed to a folding device, where they are folded to a predetermined width and stacked, while being continuously moved in a direction perpendicular to the folding direction, thereby forming a stack of inorganic fiber precursors (laminated sheet). By stacking the thin sheets in this manner, the basis weight of the laminated sheet becomes uniform throughout the sheet. As the above-mentioned folding device, the one described in JP 2000-80547 A can be used.

[0047] <<Needling Aid or Antifriction Agent Application Step>> A needling aid or antifriction agent is applied to the sheet surface of the thin sheet or laminated sheet of alumina / silica-based inorganic fiber precursor obtained by spinning, as needed. The needling aid or antifriction agent is preferably applied to both sheet surfaces.

[0048] The needling aid is not particularly limited as long as it has the effect of strengthening the threads near the mat surface of the inorganic fiber precursor aggregate, and various coating materials, for example, acrylic polymer coating materials, can be used.

[0049] The antifriction agent may be a surfactant or emulsion that reduces friction between the needle and the fiber. The needling aid or antifriction agent is applied by applying a solution or dispersion (wet coating).

[0050] <<Needling Treatment Step>> After a needling aid and / or an antifriction agent is applied to the laminated sheet of alumina / silica-based inorganic fiber precursor obtained by spinning, the laminated sheet is subjected to a needling treatment in which needles having barbs are inserted and removed from the laminated sheet. The needling treatment may be performed from only one side of the laminated sheet or from both sides. Preferably, it is performed from both sides.

[0051] The needles are preferably inserted and withdrawn in a direction perpendicular to the sheet surface of the laminate sheet. The needles are inserted deeper than the center of the laminate sheet in the thickness direction. The needles may also be inserted so as to penetrate the laminate sheet in the thickness direction.

[0052] In this way, the needling process forms needle marks on the inorganic fiber molded body 2. That is, when the needling process is performed by piercing and removing barbed needles into the laminated sheet, at least some of the fibers are caused to extend substantially in the thickness direction by the needles at the locations where the needles are pierced and removed. This forms needle marks on the surface of the inorganic fiber molded body 2. The inorganic fiber threads extending substantially in the thickness direction inside the needling-treated inorganic fiber molded body 2 are called warp threads.

[0053] The needling treatment is carried out to adjust the bulk density and peel strength of the inorganic fiber molded body 2 by forming warp threads.

[0054] The needle marks may penetrate the inorganic fiber molded body 2, or may penetrate from one mat surface and extend so as not to reach the other mat surface.

[0055] <<Firing Step>> The inorganic fiber molded body 2 is preferably a fired body obtained by firing an inorganic fiber precursor that has been subjected to a needling treatment. Firing is usually performed at a temperature of 900°C or higher, preferably 1000 to 1300°C. Firing temperatures of 900°C or higher are preferred because sufficient crystallization proceeds, resulting in alumina / silica-based fibers with excellent strength. Firing temperatures of 1300°C or lower are also preferred because excessive grain growth of the fiber crystals does not proceed, resulting in alumina / silica-based fibers with appropriate strength.

[0056] (Inorganic fiber woven fabric) The inorganic fiber woven fabric 3 covers the entire inorganic fiber molded body 2. By covering the entire inorganic fiber molded body 2 with the inorganic fiber woven fabric 3, force is distributed to the warp and weft threads, and concentration of force on the inorganic fiber molded body 2 can be avoided. In this way, the inorganic fiber woven fabric 3 compensates for and protects the fibers of the inorganic fiber molded body 2, which are prone to breaking due to mechanical impact, allowing the fire spread prevention sheet 1 to be used repeatedly. Furthermore, the inorganic fiber molded body 2 alone has poor handleability (ease of handling). This is because the inorganic fibers are exposed, which causes wear and dust generation during handling. On the other hand, by covering the entire body with the inorganic fiber woven fabric 3, handleability can be improved. This is because scattering of dust can be prevented, and dust removal is not necessary.

[0057] <Shape of inorganic fiber woven fabric> The inorganic fiber woven fabric 3 is preferably in the form of a sheet having a predetermined thickness, although it is not particularly limited. The thickness tends to increase as the basis weight (described below) increases, and is not particularly limited, but is preferably 0.01 to 0.50 mm, more preferably 0.05 to 0.40 mm, and particularly preferably 0.10 to 0.30 mm. The planar shape of the inorganic fiber woven fabric 3 is not particularly limited, and can be various shapes such as a square or a circle, and is preferably one size larger than the planar shape of the inorganic fiber molded body 2.

[0058] <Material of inorganic fiber woven fabric> The inorganic fiber woven fabric 3 is made of inorganic fiber woven fabric made of inorganic fiber yarns, and is preferably made of a flexible material that does not ignite or burn in a fire and has a certain degree of strength. Examples of inorganic fiber woven fabrics include glass fiber woven fabric and silica fiber woven fabric, and among these, glass fiber woven fabric is preferred.

[0059] <Weaving Method of Inorganic Fiber Woven Fabric> Inorganic fiber woven fabrics are fabrics in which warp and weft threads intersect, including fabrics in which warp and weft threads alternately intersect one another (e.g., plain weave), and fabrics in which at least one of the warp and weft threads crosses over or under at least two or more of the other threads (e.g., twill weave, satin weave, etc.). Note that "one thread" also includes a form in which two or more threads are bundled together. The weaving method can be selected from plain weave, twill weave, satin weave, etc., but from the viewpoint of preventing dust scattering, plain weave is preferred, and weaves in which the weave is tightly woven are particularly preferred. Furthermore, twill weave and satin weave are preferred from the viewpoints of flexibility and water permeability. Specific examples of glass fiber woven fabrics include "H201MC (product name)" and "H105MZ (product name)" manufactured by Unitika Ltd.

[0060] <Weight per unit area of ​​inorganic fiber woven fabric> The weight per unit area of ​​the inorganic fiber woven fabric 3 is not particularly limited, but is preferably 100 g / m ２ More than 150 g / m ２ The above is more preferable. This makes the inorganic fiber woven fabric 3 denser, and the inorganic fibers of the inorganic fiber molded body 2 less likely to protrude outward from the inorganic fiber woven fabric 3. Therefore, the protective performance can be maintained even with repeated use, and when used as a fire prevention cover, the covered object is less likely to be scratched. The upper limit of the basis weight is not particularly limited, but is preferably 1000 g / m ２ The following are preferable. As the basis weight increases, the weight increases and the effort required for installation and removal increases. Therefore, the basis weight can be determined appropriately taking into consideration the ease of installation and removal.

[0061] <Count and Density of Inorganic Fibers> The count (thread thickness) of the inorganic fibers used in the inorganic fiber woven fabric 3 is preferably 10 to 80 tex, more preferably 20 to 70 tex. The density of the inorganic fibers used in the inorganic fiber woven fabric 3 is preferably 20 to 70 threads / 25 mm, more preferably 30 to 60 threads / 25 mm. The count and density may be different or the same between the vertical and horizontal directions. More specifically, examples of the inorganic fiber woven fabric 3 include an inorganic fiber woven fabric 3 having a count of 65 to 70 tex and a density of 30 to 45 threads / 25 mm, and an inorganic fiber woven fabric 3 having a count of 20 to 25 tex and a density of 55 to 60 threads / 25 mm. This results in a dense weave in the inorganic fiber woven fabric 3, making it less likely for gaps to form between the weaves. Furthermore, this avoids deterioration in the ease of installation and removal of the inorganic fiber molded body 2.

[0062] <Application of Coating Material to Inorganic Fiber Woven Fabric> Depending on the weaving method, a coating material may be applied to the inorganic fiber woven fabric 3. This smooths the surface of the inorganic fiber woven fabric 3, making the surface of the coated object less susceptible to scratches. Furthermore, depending on the weaving method, a coating material need not be applied to the inorganic fiber woven fabric 3. Not applying a coating material improves flexibility and makes it easier to fold, and improves water permeability, allowing water to be sprayed onto a fire-preventing object after the fire spread prevention sheet 1 is placed over it, or it can be submerged in water to cool it. The inorganic fiber woven fabric 3 to which the coating material is applied is preferably plain weave, as described above. Applying a coating material to a plain weave results in a sheet that is less prone to deformation and is easier to stand on its own. On the other hand, when the inorganic fiber woven fabric 3 is a twill or satin weave, a coating material may or may not be applied, and the presence or absence of a coating material does not significantly affect flexibility and water permeability. Regardless of the weaving method, not applying a coating material may cause the inorganic fiber woven fabric 3 to easily fray at its edges. To prevent this, it is preferable to provide a covering material on at least a part of the edge, and more preferably to provide a covering material so as to cover the edge. Examples of the covering material include resin film, cloth, paper, etc., and it can be attached with an adhesive, etc. Commercially available cellophane tape can also be used.

[0063] Silicone resin, urethane resin, etc. can be used as the coating material, with silicone resin being preferred. The hardness of the coating material should be lower than the hardness of the contact area of ​​the coated material with the inorganic fiber woven fabric 3. The hardness can be measured by a scratch hardness test (pencil method). The coating material can be applied by brush coating, spray coating, roll coating, etc., with spray coating being preferred. For example, it can be applied using a commercially available silicone spray. The amount of coating material to be applied is not particularly limited, but is preferably 3 to 40 mg / m ２ is preferred, and 10 to 20 mg / m ２ is more preferred.

[0064] <Method for Manufacturing Fire-Spread-Arresting Sheet> The fire-spread-arresting sheet 1 can be manufactured by covering the entire inorganic fiber molded body 2 with an inorganic fiber woven fabric 3 and, if necessary, applying a coating material to the surface of the inorganic fiber woven fabric 3. To completely cover the inorganic fiber molded body 2 with the inorganic fiber woven fabric 3, for example, two sheets of inorganic fiber woven fabric 3 having the same planar shape can be stacked, the inorganic fiber molded body 2 can be sandwiched between them, and the edges can be bonded all around to cover the entire surface. Examples of methods for bonding include sewing with thread, bonding with adhesive tape such as glass cloth tape, and bonding with an adhesive such as an acrylic adhesive. The thread is preferably made of glass fiber or stainless steel fiber. Alternatively, one sheet of inorganic fiber woven fabric 3 can be folded over and stacked, the inorganic fiber molded body 2 can be sandwiched between the sheets, and the open edges can be bonded to cover the entire surface. This bonding can be performed using a method similar to that described above.

[0065] More specifically, for example, as shown in Figure 2, two rectangular inorganic fiber woven fabrics 3 are stacked on top of each other, a rectangular inorganic fiber molded body 2 is sandwiched between them, and the four sides of the inorganic fiber woven fabrics 3 are attached with adhesive tape 4, thereby covering the entire inorganic fiber molded body 2 with the inorganic fiber woven fabrics 3 and producing a fire spread prevention sheet 1.

[0066] When applying a coating material to the inorganic fiber woven fabric 3, the coating material may be applied to the inorganic fiber woven fabric 3 in advance, but it is preferable to apply the coating material after joining the edges of the inorganic fiber woven fabric 3 to cover the entire inorganic fiber molded body 2. The coating material can be applied by spraying an appropriate amount using, for example, a silicone spray.

[0067] <Physical properties of fire spread prevention sheet> In the flame insulation test shown in the examples below, the fire spread prevention sheet 1 preferably has an average back surface temperature of 300° C. or less, more preferably 250° C. or less, and particularly preferably 230° C. or less. When the temperature is within this range, the heat insulation performance is sufficient, and in the event of a fire, the surrounding area can be kept below the ignition temperature of plastic materials and the like, thereby preventing the spread of fire.

[0068] In the abrasion test shown in the Examples below, the weight loss rate of the fire spread prevention sheet 1 is preferably 0.5% or less, more preferably 0.3% or less, and particularly preferably 0.1% or less. By keeping the weight loss rate within this range, it is possible to prevent the generation of fiber powder due to abrasion and prevent contamination of products such as automobiles and batteries during storage and transportation by fiber powder. Fiber powder not only contaminates products, but also irritates the skin of workers if it becomes airborne, potentially penetrating the lungs, thereby preventing illnesses caused by such fiber powder.

[0069] <Uses of Fire Prevention Sheet> The fire prevention sheet 1 has fire resistance and heat insulation against fires, particularly fires from lithium ion batteries, and can prevent the spread of fire to the surrounding area, making it suitable for covering products equipped with lithium ion batteries (including the lithium ion batteries themselves). For example, by covering products equipped with lithium ion batteries with the fire prevention sheet 1 or by separating products, it is possible to block the flame and prevent the fire from spreading if a lithium ion battery catches fire. Furthermore, because the fire prevention sheet 1 does not easily damage the covered object, it can be used to cover products so that it comes into direct contact with them.

[0070] Examples of products equipped with lithium ion batteries include electric vehicles or hybrid vehicles, electric mobility such as electric motorcycles, residential or industrial storage batteries, home appliances, electronic devices such as personal computers, power tools, etc. Among these, lithium ion batteries are preferred for use in electric vehicles or hybrid vehicles, as they have fire resistance and heat insulation properties and are less likely to scratch the products, and are particularly preferred for use when transporting these vehicles by ship or storing them in warehouses.

[0071] (Fire spread prevention cover) The fire spread prevention sheet 1 may be used as is in sheet form, or multiple fire spread prevention sheets 1 may be joined together to form a fire spread prevention cover that matches the outer shape of the product. Furthermore, as shown in Fig. 3 or 5, multiple fire spread prevention sheets 1 may be joined together to form a large single sheet, fire spread prevention covers 5A and 5B. The fire spread prevention cover is not particularly limited, but is preferably formed by sewing multiple fire spread prevention sheets 1 together with thread, and can be formed into a three-dimensional (stereoscopic) shape or a single sheet shape. When a three-dimensional (stereoscopic) shape is used, it is preferable to form it in a shape that matches the automobile.

[0072] Examples of suture threads that can be used include inorganic fiber threads such as glass fiber threads, silica fiber threads, and alumina fiber threads, and metal fiber threads such as stainless steel fiber threads. Stainless steel fiber threads and glass fiber threads are preferred from the viewpoint of maintaining strength at room temperature, and silica fiber threads and alumina fiber threads are preferred from the viewpoint of maintaining durability at high temperatures. Specifically, examples of glass fiber threads that can be used include Unitika Ltd.'s product name "G371 / 2" and I.S.T. Co., Ltd.'s product name "YF152Z." Examples of silica fiber threads that can be used include HT-ST17 manufactured by HT Tech Co., Ltd., HT-SYB525 manufactured by HT Tech Co., Ltd., and HT-CT1280 manufactured by HT Tech Co., Ltd.

[0073] When stitching the fire spread prevention sheet 1, it is preferable to use at least two threads, sewn in parallel with an appropriate spacing. The at least two threads are preferably at least two types selected from the threads described above. Using two types of threads makes the sheet less likely to unravel under various conditions. For example, by using a combination of stainless steel fiber threads and silica fiber threads, the silica fiber threads are more durable than the inorganic fibers of the inorganic fiber woven fabric at high temperatures, such as 1000°C or higher, during combustion, but less durable than the inorganic fibers of the inorganic fiber woven fabric at room temperature. Conversely, the stainless steel fiber threads are more durable than the silica fiber threads at room temperature, but less durable than the silica fiber threads at high temperatures. Therefore, by combining these threads, the weaknesses of each can be compensated for. In this invention, durability refers to the rate of decrease in tension of the stitched threads per unit time (e.g., 1 hour) when placed at a specified temperature. Furthermore, "high temperature" refers to the temperature during combustion, for example, 800°C or higher, 1000°C or higher, or 1200°C or higher, and "room temperature" refers to ordinary temperature, for example, 10°C to 30°C, 15°C to 25°C, or 20°C to 25°C.

[0074] The distance between the at least two threads is not particularly limited, but is preferably a constant distance, for example, preferably 3 mm to 15 mm, more preferably 4 mm to 10 mm, and particularly preferably 5 mm to 8 mm. If the distance is shorter than 3 mm, the needle holes will be close to each other during sewing, which will cause significant damage to the inorganic fiber molded product or the inorganic fiber woven fabric and make them more likely to unravel.

[0075] For example, when making a three-dimensional fire prevention cover for an automobile, fire prevention sheets can be made to fit each side of the automobile except for the bottom, and each side can be connected with thread or the like to create a three-dimensional cover that fits the shape of the automobile.

[0076] The fire spread prevention sheet 1 or fire spread prevention cover may be rolled up by the high-pressure gas generated during a fire, causing it to lose its fire spread prevention performance. Therefore, it is preferable to provide a fastener for securing the sheet or cover to the product. Examples of fasteners include strings or belts that can be tied to the product, and hooks or rings that can be hung on the product. When the fire spread prevention cover is for use with an automobile, a fastener for securing the cover to a lashing belt, which is used to secure the automobile to the floor of a car carrier, may be used.

[0077] Furthermore, if the fire spread prevention cover is made into a single sheet, it can be folded and stored normally, and taken out and used to cover the burning object in the event of a fire. The single sheet fire spread prevention cover can be made by sewing together long fire spread prevention sheets 1, and can be made into fire spread prevention covers 5A, 5B as shown in Figure 3 or Figure 5, for example.

[0078] As shown in Figure 3 or Figure 4, the fire spread prevention cover 5A is made by using three or more long fire spread prevention sheets 1, each 250 cm long and 128 cm wide, overlapping each sheet with the edges aligned and sewing the left and right longitudinal edges together in an alternating order, so that the fire spread prevention cover 5A has a folding screen shape with the seams 8A appearing alternately on both sides, as shown in Figure 3. This makes it easy to fold, as shown in Figure 4, and when unfolding, it automatically unfolds into a sheet shape by lifting the longitudinal edges of the cover, making it possible to provide a cover that can be used to quickly prevent the spread of fire in an emergency.

[0079] The fire spread prevention cover 5A is preferably sewn together by parallel stitching at least two threads, including a first thread 7A and a second thread 6A, to form a seam 8A. Preferably, the second thread 6A located on the inner side is a stainless steel fiber thread or a glass fiber thread, and the first thread 7A located on the outer side is a silica fiber thread or an alumina fiber thread. Because the stainless steel fiber thread or the glass fiber thread 6A has strength at room temperature, it can prevent the fire spread prevention sheet 1 from coming apart even when a load is applied when unfolding the cover 5A. Because the silica fiber thread or the alumina fiber thread 7A has strength at high temperatures, when the fire spread prevention cover 5A is used in a fire, even if the stainless steel fiber thread or the glass fiber thread 6A melts due to heat, the silica fiber thread or the alumina fiber thread 7A can prevent the fire spread prevention sheet 1 from coming apart.

[0080] As shown in Figures 5 and 6, the fire spread prevention cover 5B is made by using three or more long fire spread prevention sheets 1, each measuring, for example, 250 cm long and 128 cm wide, overlapping the longitudinal edges of each fire spread prevention sheet 1 in a palm-to-palm fashion and sewing along the longitudinal edges to form a seam 8B. As shown in Figure 5, the seam 8B is visible on one side of the fire spread prevention cover 5A, and adjacent longitudinal edges are overlapped and sewn together in a palm-to-palm fashion. Therefore, by overlapping and folding the seam 8B as shown in Figure 6, each fire spread prevention sheet can be folded in half widthwise for compact storage. In this case, the sheets are preferably sewn together in parallel using at least two threads, including a first thread 7B and a second thread 6B, similar to the fire spread prevention cover 5A. Preferably, the inner second thread 6B is stainless steel fiber thread or glass fiber thread, and the outer first thread 7B is silica fiber thread or alumina fiber thread.

[0081] The inorganic fiber woven fabric 3 used for the fire spread prevention covers 5A, 5B can be selected from twill, satin, or plain weave glass fiber woven fabric depending on the desired characteristics. If no coating material is applied to the surface of the inorganic fiber woven fabric 3, this increases flexibility and makes it easier to fold. It also increases water permeability, allowing water to be sprayed over the fire spread prevention covers 5A, 5B placed over a burning object to cool the covered object during fire extinguishing.

[0082] (Lithium-ion battery product case) The fire-prevention sheet 1 may be used as the lining of a lithium-ion battery product case for storing or transporting lithium-ion batteries or products equipped with lithium-ion batteries. This can block the flame if a lithium-ion battery inside the case catches fire during transport or storage, preventing the flame from spreading outside the case. The case may be a conventional box-shaped case, preferably a collapsible container. The fire-prevention sheet 1 can be attached to the inside of the case with an adhesive or the like to create a lithium-ion battery product case.

[0083] (Effects) The fire spread prevention sheet 1 has heat resistance and thermal insulation properties, and can prevent the spread of fire caused by a fire such as a lithium-ion battery from spreading to surrounding objects and facilities, or conversely, protect equipment equipped with lithium-ion batteries from surrounding flames. Therefore, the present invention can reduce fire damage during storage and transportation of lithium-ion batteries and products equipped with them. Furthermore, the fire spread prevention sheet 1 with a coating applied to its surface is less likely to scratch the surface of the covered object, making it suitable for use on painted products such as tablet devices and automobiles. The fire spread prevention sheet 1 without a coating on its surface has excellent flexibility and water permeability, making it possible to fabricate a foldable fire spread prevention cover that is easy to store.

[0084] An example of the fire spread prevention sheet of the present invention will be described below, but the present invention is not limited to this example.

[0085] Examples 1 to 4 and Comparative Examples 1 to 3 shown below were prepared.

[0086] [Example 1] (Inorganic fiber molded body) Silica sol was added to an aqueous solution of basic aluminum chloride (aluminum content 165 g / L, Al / Cl=1.8 (atomic ratio)) to obtain an inorganic fiber molded body. ２ O ３ : SiO ２ Polyvinyl alcohol was then added, and the mixture was concentrated to prepare a spinning solution having a viscosity of 70 poise (25°C) and an alumina / silica content of approximately 35% by mass.

[0087] The spinning solution was spun by a blowing method. A spinning nozzle with the same structure as that shown in Fig. 6 of Japanese Patent No. 2602460 was used. For collection, an endless wire mesh belt was installed at a substantially right angle to the spinning airflow, and the spinning airflow containing the alumina / silica-based fiber precursor was collided with the rotating endless belt to collect the fiber as a continuous sheet (thin sheet).

[0088] The thin sheets collected from the stacking device were sprayed with a lubricant, then continuously drawn out and fed to a folding device, where they were folded to a predetermined width and stacked, while being continuously moved perpendicular to the folding direction to form a laminated sheet. The folding device used was a folding device with a structure similar to that described in JP 2000-80547 A.

[0089] The basis weight can be changed by changing the number of times the fiber precursor is folded by the stacking device.

[0090] The mat-like aggregate of alumina / silica-based fiber precursor obtained by spinning was subjected to a needling treatment using needles. The needling treatment was performed by punching using a needle punching machine. The needling treatment with needles was performed on both sides. When the needling treatment was performed on the laminated sheet of inorganic fiber precursor, the needles were needled so that they penetrated from one side to the other, so that a predetermined needle penetration density was achieved after firing, and so that an average of five barbs per needle penetrated to the other side.

[0091] Then, it is fired at 1200°C and the weight is 600g / m ２ An inorganic fiber molded body made of crystalline alumina / silica-based fibers was obtained. Firing was performed in an electric furnace, raising the temperature to 1200°C at a rate of 5°C / min, holding at 1200°C for 30 minutes, and then allowing to cool naturally. This inorganic fiber molded body was cut out using a punching die to a length of 150 mm and a width of 100 mm.

[0092] The composition ratio of this crystalline alumina / silica-based fiber was alumina / silica = 72 / 28 (mass ratio), and the average fiber diameter (average value of 100 fibers) of the crystalline alumina / silica-based fibers measured by microscopic observation of the inorganic fiber blanket was 5.5 μm. The thermal conductivity of this inorganic fiber molded product at 1000 °C was measured by the transient hot wire method and was 0.30 W / m K. The softening point of the inorganic fiber molded product was measured by penetration measurement using an alumina pin and was 1000 °C or higher.

[0093] (Inorganic fiber woven fabric) As an inorganic fiber woven fabric, a thickness of 0.17 mm and a basis weight of 204 g / m ２ , bulk density 1.200 g / cm ３ A glass fiber woven fabric (H201MC manufactured by Unitika Ltd.) was used. The glass fiber woven fabric was plain woven and cut into a rectangular shape with a length of 200 mm and a width of 200 mm.

[0094] (Sheet) Two sheets of inorganic fiber woven fabric were stacked, the inorganic fiber molded body was sandwiched between them, and the sheets were bonded together with glass cloth tape (product name: Glass Cloth Tape 361, manufactured by 3M Co.) so as to close the four outer edges, and the total basis weight of the inorganic fiber woven fabric was 400 g / m ２ The sheet was Example 1. The total basis weight is the sum of the basis weights of the inorganic fiber woven fabrics on the front and back surfaces.

[0095] [Example 2] The inorganic fiber woven fabric of Example 1 was prepared using a fabric with a thickness of 0.26 mm and a basis weight of 314 g / m ２ , bulk density 1.208 g / cm ３ The total weight of the inorganic fiber woven fabric was 600 g / m. ２ The sheet was used as Example 2.

[0096] [Example 3] The inorganic fiber woven fabric of Example 1 was prepared using a fabric with a thickness of 0.09 mm and a basis weight of 102 g / m ２ , bulk density 1.133 g / cm ３ The total weight of the inorganic fiber woven fabric was 200 g / m. ２ The sheet was used as Example 3.

[0097] [Example 4] A silicone spray (product name "HS Silicone Spray (Dry)" manufactured by AZ) was applied to each of the front and back surfaces of the sheet of Example 1 at a rate of approximately 16 g / m. ２ The sheet was sprayed with silicone resin at 1000 W ...

[0098] Comparative Example 1 The sheet of Comparative Example 1 was prepared using only the glass fiber woven fabric used in Example 1.

[0099] Comparative Example 2 A sheet of Comparative Example 2 was prepared using only the inorganic fiber molded product used in Example 1.

[0100] Comparative Example 3: A silicone spray (product name "HS Silicone Spray (Dry)" manufactured by AZ) was applied to each of the front and back surfaces of the inorganic fiber molded article used in Example 1 at a rate of approximately 16 g / m ２ The sheet was sprayed with silicone resin at 1000 W ...

[0101] <Softening Point Temperature Test Method> An alumina pin with an outer diameter of 1.0 mm and a length of 25 mm was embedded in the inorganic fiber molding to a depth of 5 mm, and the temperature was raised to a predetermined temperature at a rate of 6°C / min while applying a load of 0.2 MPa. After maintaining that temperature for 1 hour, the height of the alumina pin was measured. The temperature at which the height of the alumina pin was displaced by 20% was taken as the softening point temperature. In other words, if the height displacement of the alumina pin was less than 20%, the softening point temperature was determined to be higher than the predetermined temperature, and if the displacement was greater than 20%, the softening point temperature was determined to be lower than the predetermined temperature. In this example, 1000°C and 1200°C were selected as the predetermined temperatures.

[0102] <Evaluation> The above test was performed on N=3 inorganic fiber molded bodies. When the predetermined temperature was 1000°C, the height variations of the alumina pins were 2.4%, 4.1%, and 1.1%, respectively. Therefore, the softening point temperature of the inorganic fiber molded body in this example is 1000°C or higher. When the predetermined temperature was 1200°C, the height variations of the alumina pins were 0.5%, 0.8%, and 2.0%, respectively. Therefore, the softening point temperature of the inorganic fiber molded body in this example is 1200°C or higher.

[0103] (Flame Heat Insulation Test) The following flame heat insulation test was carried out using the sheets of Examples 1 and 2 and Comparative Example 1.

[0104] <Test Method> Thermocouples were attached to both sides of the sheets of Examples 1 and 2 and Comparative Example 1, and the sheets were heated with a Bunsen burner to raise the temperature of the front surface to 1000°C. After the front surface temperature stabilized at 1000°C, the back surface temperature was measured for 3 minutes, and the average of these temperatures was taken as the average back surface temperature. The average value can be calculated by arithmetic averaging.

[0105] <Judgment> If there were no penetration holes and the flame was blocked, and the average temperature of the back surface opposite the flame was 300°C or less, it was judged to have passed, as it could be said that the automotive exterior plastic would not ignite. If the sheet had holes penetrated by the flame or the average back surface temperature exceeded 300°C, there was a risk of the fire spreading, so it was judged to have failed. The presence or absence of penetration holes was confirmed visually.

[0106] <Results> The results of the insulation test are shown in Table 1 below.

[0107]

[0108] <Discussion> From the test results, it is determined that Examples 1 and 2 have flame-blocking and heat-insulating properties against a 1000°C flame, the temperature on the back surface is kept below 300°C, and the spread of fire can be prevented. In contrast, in Comparative Example 1, the holes are penetrated and the flame cannot be blocked. From this point of view, it is determined that the inorganic fiber woven fabric alone does not have sufficient flame-blocking and heat-insulating properties against a 1000°C flame, and it is unable to keep the temperature of surrounding plastic materials below the ignition temperature, making it unable to prevent the spread of fire.

[0109] [Wear Test] The following wear test was carried out using Examples 1 and 3 and Comparative Example 2.

[0110] <Test Method> The surface of a 120 mm long x 60 mm wide stainless steel plate (SUS430) was roughened with 80 mesh waterproof abrasive paper, and each sheet was placed on top of it. A 2.3 kg weight was then placed on top of the sheet, and the weight was repeatedly slid in a 50 mm stroke along the length of the stainless steel plate. The progress of wear was evaluated from the weight loss rate of each sheet after 100, 150, and 200 slides. The weight loss rate was calculated using the following formula: Weight loss rate = (sheet weight before test - sheet weight after test) / sheet weight before test

[0111] <Results> The test results are shown in Table 2. The relationship between the number of slides and the weight change is shown in a graph in FIG.

[0112]

[0113] (Discussion) From the test results, it was determined that Examples 1 and 3 were resistant to wear even with repeated use and could be used for a long period of time. In contrast, it was found that wear progressed in proportion to the number of times of friction in Comparative Example 2. From this point of view, it is believed that covering the entire inorganic fiber molded product with an inorganic fiber woven fabric would be suitable as a fire prevention sheet or cover for products equipped with lithium-ion batteries, such as electric vehicles.

[0114] [Damage Test] The following damage test was carried out using Examples 1, 3, and 4 and Comparative Examples 2 and 3.

[0115] <Test method> Each sheet was placed on a coated plate (automotive paint (black) Toyota No. 202 test piece SPCC-SD cationic electrodeposition + urethane coating) measuring 120 mm in length x 120 mm in width x 0.8 mm in thickness, and a 4.2 kg weight was placed on top of it. The weight was then slid in the length direction of the coated plate, and this sliding was repeated 10 times. The surface of the coated plate after sliding was photographed with a microscope (magnification 200x, manufactured by KEYENCE Corporation, "Digital Microscope VHX-5000" product name), and the photograph was then visually observed.

[0116] <Results> Micrographs of Examples 1, 3, and 4 and Comparative Examples 2 and 3 are shown in FIGS. 4 to 8, respectively.

[0117] Comparing Example 1 (FIG. 8) and Example 3 (FIG. 9) with Comparative Example 2 (FIG. 11), it was confirmed that Examples 1 and 3, in which the inorganic fiber molded body was covered with an inorganic fiber woven fabric, had fewer scratches and were less likely to scratch the surface of the coated plate. Comparing Example 1 (FIG. 8) with Example 4 (FIG. 10), it was confirmed that Example 4, in which a silicone resin was applied, had fewer scratches and was less likely to scratch the surface of the coated plate. Comparing Comparative Example 2 (FIG. 11) with Comparative Example 3 (FIG. 12), no difference was observed in the number of scratches on the surface of the coated plate when the silicone resin was applied directly to the inorganic fiber molded body. Furthermore, comparing Example 1 (FIG. 8) with Example 3 (FIG. 9), it was confirmed that the inorganic fiber woven fabric in Example 1, which had a larger basis weight, had fewer scratches and was less likely to scratch the surface of the coated plate.

[0118] <Discussion> It was found that when an inorganic fiber molded body is entirely covered with a large-area inorganic fiber woven fabric and a silicone resin is further applied to the surface of the inorganic fiber woven fabric, the surface of the coated object is less likely to be damaged. From this point of view, it is believed that the fire-preventing sheet of the present invention is suitable for covering painted products such as automobiles.

[0119] [Water permeability test] Test specimens were prepared using the following glass fiber woven fabrics and the inorganic fiber molded article prepared in Example 1, cut into A3 size pieces, and subjected to a water permeability test. (1) Surface-coated twill glass fiber woven fabric (basis weight 313 g / m ２ (2) Plain woven glass fiber fabric without surface coating (weight 211 g / m ２ (3) Surface-coated plain weave glass fiber woven fabric (basis weight 210 g / m ２ ; "H202M205F" manufactured by Unitika Ltd.

[0120] The A3-sized inorganic molded body and each of the above glass fiber woven fabrics were cut to a size slightly larger than A3 size. Two sheets of this glass fiber woven fabric were stacked, the inorganic fiber molded body was sandwiched between them, and the four edges were sewn with stainless steel fiber thread (HT-SYB525, manufactured by HT Tech Co., Ltd.). A water-absorbent mat (17 cm long x 12.5 cm wide x 2 mm thick, product name: Super Absorbent Mat Sham Dry (registered trademark)) made of 80% rayon and 20% polypropylene was sandwiched between each half-folded test body and then folded in half again, i.e., the test body was folded in quarters. The corner where the water-absorbent mat was located was immersed in water and removed after 30 seconds, and the water absorption of the water-absorbent mat was measured. After the measurement, the test body was returned to its quarter-folded state and submerged for another 30 seconds, and the water absorption was measured. Similar measurements were then performed every minute. The results are shown in the graph in Figure 13.

[0121] <Results> (1) The surface-coated twill glass fiber woven fabric (triangle marks in the graph in Figure 13) had a water absorption of 41 g after 30 seconds, reaching saturation. Therefore, no further measurements were taken. (2) The surface-uncoated plain-weave glass fiber woven fabric (solid line with square marks in the graph in Figure 13) had a water absorption of 41 g after 1 minute, reaching saturation. Therefore, no further measurements were taken. (3) The surface-coated plain-weave glass fiber woven fabric (solid line with diamond marks in the graph in Figure 13) had a water absorption of 41 g after 5 minutes, reaching saturation.

[0122] <Discussion> It was confirmed that water permeability increases in the following order: twill weave with surface coating, plain weave without surface coating, and plain weave with surface coating. Therefore, it was understood that the use of twill glass fiber fabric is suitable for making a fire prevention cover with excellent water permeability.

[0123] [Flexibility Test] In the flexibility test, the specimen used in the water permeability test was used.

[0124] As shown in Figure 14, each test sheet was placed on a test stand with one long edge extending outward by 12 cm, and a fixing weight was placed on top of the test sheet to fix it in place. A weight was attached to double-sided tape attached 10 cm from the edge of the test stand, and a load was applied to each test piece. The applied weight was measured to cause a vertical deflection of 1 cm, 2 cm, or 4 cm for each test piece. The results are shown in the graph in Figure 15.

[0125] <Results> The test sheet using the twill-woven glass fiber woven fabric (solid line with triangles in the graph in Figure 15) deflected by more than 4 cm even without applying a load. The test sheet using the plain-woven glass fiber woven fabric without a surface coating (solid line with squares in the graph in Figure 15) deflected by 2 cm without applying a load, and by 4 cm with a load of 9 g. The test sheet using the plain-woven glass fiber woven fabric with a surface coating (solid line with diamonds in the graph in Figure 15) deflected by 1 cm with a load of 3 g, 2 cm with a load of 10 g, and 4 cm with a load of 29 g.

[0126] <Discussion> It was confirmed that flexibility increases in the following order: twill weave with surface coating, plain weave without surface coating, and plain weave with surface coating. It was confirmed that twill glass fiber woven fabric is best used when flexibility is required, such as for making it easier to fold as a fire prevention sheet or cover.

[0127] REFERENCE SIGNS LIST 1 Fire prevention sheet 2 Inorganic fiber molded body 3 Inorganic fiber woven fabric 4 Adhesive tape 5A, 5B Fire prevention cover 6A, 6B Second thread 7A, 7B First thread 8A, 8B Seam

Claims

1. A fire prevention sheet comprising an inorganic fiber molded body having a softening point of 1000°C or higher and a thermal conductivity at 1000°C of 0.5 W / m·K or less, and an inorganic fiber woven fabric covering the entire body.

2. The fire prevention sheet according to claim 1, wherein the inorganic fiber woven fabric is made of glass fiber.

3. The inorganic fiber woven fabric has a basis weight of 100 g / m ２ 3. The fire spread prevention sheet according to claim 2, wherein the above-mentioned 4. The fire spread prevention sheet according to claim 1, wherein the inorganic fiber woven fabric is a fabric in which warp threads and weft threads are alternately crossed, and is a fabric to which no coating material is applied.

5. The fire spread prevention sheet according to claim 4, which has a covering material covering at least a part of the edge of the inorganic fiber woven fabric.

6. The fire spread prevention sheet according to claim 1, wherein the inorganic fiber woven fabric is a fabric in which warp threads and weft threads are alternately crossed and to which a coating material is applied.

7. The fire spread prevention sheet according to claim 1, wherein the inorganic fiber woven fabric is a fabric in which at least one of the warp and weft threads crosses over or under at least two or more of the other threads.

8. The fire spread prevention sheet according to claim 1, wherein the inorganic fiber molded body is a needle blanket containing alumina / silica fibers.

9. The inorganic fiber molded body has a basis weight of 300 g / m ２ The fire spread prevention sheet according to claim 8, wherein the fire spread prevention sheet is as described above.

10. A fire spread prevention cover formed by sewing together a plurality of fire spread prevention sheets according to any one of claims 1 to 9 with thread, wherein the thread has a first thread that is more durable at high temperatures than the inorganic fibers of the inorganic fiber woven fabric.

11. The fire spread prevention cover according to claim 10, wherein the yarn includes a second yarn that is more durable at room temperature than the first yarn.

12. A fire prevention cover as described in claim 11, wherein the first thread is located on the edge side of the fire prevention sheet, and the second thread is located inside the fire prevention sheet more than the first thread and extends parallel to the first thread.

13. A fire prevention cover as described in claim 10, in which three or more fire prevention sheets are connected by stitching formed with the thread, and the stitching is arranged alternately on both sides of the fire prevention cover.

14. A fire prevention cover as described in claim 10, in which three or more fire prevention sheets are connected by seams formed with the thread, and the seams are located on one side of the fire prevention cover.

15. The fire prevention cover according to claim 10, which is used to cover a product equipped with a lithium ion battery.

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