Inorganic fiber blanket, laminate, battery pack unit, and electric mobility

Abstract

Provided are an inorganic fiber blanket having excellent flame-shielding properties, a battery pack cover using the inorganic fiber blanket, a battery pack unit using the battery pack cover, and an electric mobility using the battery pack unit. The inorganic fiber blanket is formed of a needle blanket having a basis weight of 700 g / m2 or less, and a bulk density of 0.125 g / cm3 or more. The battery pack cover includes this inorganic fiber blanket. The battery pack unit uses this battery pack cover. The electric mobility uses this battery pack unit.

Description

Inorganic fiber blanket, laminate, battery pack unit and electric mobility

[0001] The present invention relates to an inorganic fiber blanket, a laminate, a battery pack unit, and an electric mobility device.

[0002] A battery pack unit used in electric mobility such as an electric vehicle (EV) has a housing and a battery pack disposed within the housing (Patent Document 1: WO2019 / 044801).

[0003] Patent Document 1 describes that the container is made of a laminate in which a non-combustible or flame-retardant fiber layer such as glass fiber is provided on one surface of a synthetic resin plate.

[0004] International Publication No. 2019 / 044801

[0005] In the case of battery packs for EVs, the energy density of battery modules installed in electric vehicles is on the rise in order to extend driving distances, and there are growing demands for measures to prevent battery heat generation and the risk of thermal runaway. In the event of a battery fire due to thermal runaway or other reasons, a fire-resistant material with excellent flame-blocking properties is required in the gap between the battery pack and the battery pack cover to delay the spread of the fire to interior components. However, the gap between the battery pack and the battery pack cover is limited, so the fire-resistant material must be thin. If the material is too thick, there is a risk of either the battery pack or the battery pack cover collapsing. On the other hand, if the thickness of the fire-resistant material is too thin, it will not be able to exhibit sufficient flame-blocking properties.

[0006] An object of the present invention is to provide an inorganic fiber blanket with excellent flame-blocking properties. Another object of the present invention is to provide a laminate using this inorganic fiber blanket, a battery pack unit having this inorganic fiber blanket, and an electric mobility using this battery pack unit.

[0007] The present inventors have found that an inorganic fiber blanket with a high bulk density can be obtained by devising a needling process, and further found that an inorganic fiber blanket with a specific bulk density and basis weight can achieve both thickness and flame-blocking performance.

[0008] [1] Basis weight 700g / m ２ or less, and a bulk density of 0.125 g / cm ３ An inorganic fiber blanket comprising the above needle blanket.

[0009] [2] The needle blanket has needle penetration marks penetrating from one surface to the other surface, and the density of the needle penetration marks is 35 / cm ２ The inorganic fiber blanket according to [1] below.

[0010] [3] Basis weight 700g / m ２ or less, and a bulk density of 0.125 g / cm ３ The inorganic fiber blanket described above is characterized in that it is not penetrated for 5 minutes in a flame test at a flame temperature of 1000°C and an air jet speed of 100 m / s, using a laminate consisting of the inorganic fiber blanket and an aluminum alloy plate with a thickness of 0.8 mm as a test specimen.

[0011] [4] The inorganic fiber blanket according to any one of [1] to [3], having a peel strength of 4.0 N or more as determined by the following method. <Method for measuring peel strength> Measurement is performed using a tensile tester. The size of the effective portion of the test piece is 50 mm x 75 mm. A slit is made in the thickness center of one end on the 50 mm width side, extending 25 mm in the longitudinal direction. Both ends of the slit are gripped and attached to the tensile tester, and the blanket is pulled at a speed of 100 mm / min. The maximum load is defined as the peel strength.

[0012] [5] A laminate comprising the inorganic fiber blanket according to any one of [1] to [4] and a substrate.

[0013] [6] The laminate according to [5], wherein the substrate is a metal substrate.

[0014] [7] The laminate according to [6], wherein the metal is aluminum, an aluminum alloy, magnesium, a magnesium alloy, titanium, a titanium alloy, iron, or stainless steel.

[0015] [8] The laminate according to any one of [5] to [7], which is used as a battery pack cover.

[0016] [9] A battery pack unit having the inorganic fiber blanket according to any one of [1] to [4].

[0017]

[10] A battery pack unit having the laminate according to [8] and a battery pack, in which the inorganic fiber blanket of the laminate is disposed on the battery pack side.

[0018]

[11] A battery pack unit having the laminate according to [8] and a battery pack, wherein the base material of the laminate is disposed closer to the battery pack than the inorganic fiber blanket.

[0019]

[12] An electric mobility vehicle equipped with any one of the battery pack units according to [9] to

[11] .

[0020] The inorganic fiber blanket used in the present invention has a small basis weight and a high bulk density, and therefore has excellent flame-blocking properties even when it is thin. Therefore, a battery cover equipped with this inorganic fiber blanket has excellent flame-blocking properties.

[0021] Fig. 2 is a schematic cross-sectional view of a battery pack unit. Fig. 3 is a schematic cross-sectional view of a battery pack unit, in which a canopy portion and a box portion for storing a battery pack are separated compared to Fig. 1. Fig. 4 is an explanatory diagram of a peel test method. Fig. 5 is an explanatory diagram of a peel test method. Fig. 6 is an explanatory diagram of needling.

[0022] [Inorganic fiber blanket] The inorganic fiber blanket of the present invention has a basis weight of 700 g / m ２ or less, and a bulk density of 0.125 g / cm ３ The inorganic fiber blanket may be a nonwoven fabric or a woven fabric, as long as it is a blanket-shaped (sheet-shaped) fiber having a predetermined thickness.

[0023] The basis weight (mass per unit area) of the inorganic fiber blanket is 700 g / m ２ Preferably 650 g / m or less ２ Particularly preferably 600 g / m ２ By setting the basis weight within the above range, the thickness range of the inorganic fiber blanket can be restricted, allowing it to be accommodated in a limited space. This is also preferable from the viewpoint of reducing the weight of the vehicle body.

[0024] The basis weight of the inorganic fiber blanket is preferably 300 g / m ２ More preferably, 400 g / m ２ More preferably, 500 g / m ２ If the basis weight is within the above range, the flame-blocking performance can be further improved in terms of the amount of fibers per unit area.

[0025] The bulk density of the inorganic fiber blanket is 0.125 g / cm ３ or more, preferably 0.130 g / cm ３ There is no upper limit to the bulk density, but it is preferably 0.200 g / cm ３ Particularly preferably 0.150 g / cm ３ The following is the result.

[0026] Bulk density is 0.125 g / cm ３ If the amount of fiber per unit volume is above this, the amount of fiber per unit volume is sufficient, and the battery pack can have flame-blocking properties and wind pressure resistance against explosion due to thermal runaway.

[0027] The thickness of the inorganic fiber blanket (measured by the method described in the Examples below) is preferably 0.1 mm or more, more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more, and is preferably 5.0 mm or less, more preferably 4.0 mm or less, and particularly preferably 3.0 mm or less.

[0028] The basis weight and thickness of the inorganic fiber blanket can be set within the above range by adjusting the amount of fiber per unit area when the inorganic fiber aggregates that make up the inorganic fiber blanket are stacked in a folding device.

[0029] The inorganic fibers constituting this inorganic fiber blanket are not particularly limited, and examples thereof include single or composite fibers of silica, alumina / silica, and zirconia, spinel, titania, etc. The inorganic fibers are preferably alumina / silica-based fibers, and particularly preferably crystalline alumina / silica-based fibers. The alumina / silica composition ratio (mass ratio) of the alumina / silica-based fibers is preferably in the range of 60 to 95 / 40 to 5, more preferably 70 to 84 / 30 to 16, and particularly preferably 70 to 76 / 30 to 24.

[0030] The inorganic fibers preferably have an average fiber length of 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. ３ mm or less, more preferably 1.0 × 10 ３ The inorganic fibers are fibers having a length of 1 / 2 mm or less. The average fiber diameter of the inorganic fibers is preferably 3 to 10 μm, and particularly preferably 5 to 8 μm. If the average fiber length and average fiber diameter of the inorganic fibers are within these ranges, the inorganic fiber blanket will have high tensile strength, which is preferable. If the average fiber length and average fiber diameter of the inorganic fibers are within these ranges, the amount of dust floating in the air can be reduced, which is also preferable. The average fiber length of the inorganic fibers is the average value of 300 fibers measured by observation with a microscope. The average fiber diameter is the average value of 100 fibers measured by observation with a microscope.

[0031] The inorganic fiber blanket of the present invention can be obtained by various methods, for example, a papermaking method or a needling method.

[0032] The inorganic fiber blanket is preferably a needle blanket that has been subjected to a needling treatment. By performing the needling treatment, needle penetration marks that penetrate from one surface to the other surface are formed in the inorganic fiber blanket. Hereinafter, the surface perpendicular to the thickness direction of the inorganic fiber blanket may be referred to as the mat surface. Also, the side surface (thickness direction surface) of the inorganic fiber blanket perpendicular to the mat surface may be referred to as the end surface. That is, the inorganic fiber blanket in the first aspect of the present invention has a basis weight of 700 g / m２ or less, and a bulk density of 0.125 g / cm ３ The inorganic fiber blanket includes the above needle blanket.

[0033] <Needle penetration mark density> When visible light is irradiated onto the matte surface of the inorganic fiber blanket, the amount of light transmitted through the needle penetration marks is greater than the amount of light transmitted through areas other than the needle penetration marks, and the transmitted light is observed as light spots on the peeled surface. The number of light spots due to transmission to the peeled surface can be counted to determine the number of needle penetration marks.

[0034] In addition, the unit area (1 cm ２ The number of needle penetration marks per mat (needle penetration mark density) is preferably 35 marks / cm as an average value over the entire mat surface. ２ or less, more preferably 32 particles / cm ２ Setting the number of needle penetration marks within the above range is preferable from the viewpoints that wind pressure resistance can be provided against explosion due to thermal runaway of the battery pack, and that the thickness can be controlled within a range that allows insertion between the battery pack and the substrate.

[0035] In the present invention, the unit area (1 cm ) of the mat surface of the inorganic fiber blanket ２ The number of needle penetration marks per mat (needle penetration mark density) is preferably 5 marks / cm on average over the entire mat surface. ２ More preferably, 6 particles / cm ２ If the number of needle penetration marks is within the above range, the interlayer peel strength and tensile strength of the entire mat are improved in terms of the amount of restraint of the fibers by the warp yarns, and the flame-blocking performance can be improved.

[0036] The inorganic fiber blanket in the second aspect of the present invention has a basis weight of 700 g / m ２ or less, and a bulk density of 0.125 g / cm ３ The above inorganic fiber blanket is an inorganic fiber blanket in which the laminate is not penetrated for 5 minutes in a flame test at a flame temperature of 1000°C and an air jet speed of 100 m / s.

[0037] <Peel Strength> The inorganic fiber blanket of the present invention preferably has a peel strength determined as a load peak (N) in a peel test described below of 4.0 N or more, more preferably 5.0 N or more, and particularly preferably 6.0 N or more. The higher the peel strength of the inorganic fiber blanket, the more advantageous it is.

[0038] A peel strength of 4.0 N or more is preferable in terms of providing wind pressure resistance against explosions due to thermal runaway of the battery pack. Furthermore, when the battery pack is bonded to the cover substrate using an adhesive, peeling is unlikely to occur at the surface layer, and the battery pack can maintain adhesion without falling off the substrate during driving.

[0039] <Peel Test> A test piece of 50 mm × 75 mm was die-cut out from an inorganic fiber blanket, and a 25 mm deep notch was made in the center of the thickness of one end face in the longitudinal direction of this test piece 11 as shown in Figures 3 and 4 . Both ends formed by the notch were supported by gripping jigs 12, and the test piece was then set in a tensile tester and pulled in opposite directions perpendicular to the mat surface at a speed of 100 mm / min, and the maximum load value was defined as the peel strength.

[0040] <Tensile strength> The inorganic fiber blanket preferably has a tensile strength of 20 N or more, preferably 25 N or more, particularly preferably 30 N or more. The higher the tensile strength of the inorganic fiber blanket, the better, and there is no upper limit, but it is preferably 100 kN or less, particularly preferably 50 kN or less. The tensile strength is a value measured by the method described in the examples below.

[0041] [Method for manufacturing inorganic fiber blanket] The inorganic fiber blanket can be obtained by various methods, for example, it can be manufactured by a papermaking method or a needling method. In the papermaking method, inorganic fibers are opened, and the opened inorganic fibers are dispersed in a solvent to obtain a mixed liquid, which is then subjected to a solvent removal treatment and dried to obtain a paper mat. In the needling method, it can be manufactured by, for example, the following method.

[0042] [Method for manufacturing a needled blanket] The needled blanket 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 (aggregate) of inorganic fiber precursors to a needling treatment, and a firing step of firing the needled mat-like aggregate of inorganic fiber precursors to form an inorganic fiber blanket. However, the needled blanket may also be manufactured by a method other than this.

[0043] Hereinafter, an example of a method for producing a needling-treated inorganic fiber blanket will be described using a method for producing an alumina / silica-based fiber blanket as an example. However, the inorganic fiber blanket of the present invention is not limited to an alumina / silica-based fiber blanket and may be a blanket made of silica, zirconia, spinel, titania, or composite fibers thereof, as described above.

[0044] <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.

[0045] <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.

[0046] The spinning solution contains aluminum from basic aluminum chloride and silicon from silicon compound in a ratio of Al ２ O ３ and SiO２ In terms of mass ratio, the aluminum concentration is usually 99:1 to 65:35, preferably 99:1 to 70:30, and the aluminum concentration is preferably 150 to 210 g / L and the organic polymer concentration is preferably 15 to 50 g / L.

[0047] 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.

[0048] When the aluminum concentration in the spinning solution is less than 150 g / L or the organic polymer concentration is less than 15 g / L, the spinning solution does not have an appropriate viscosity, resulting in a small fiber diameter for the resulting alumina / silica-based fibers. That is, 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 150 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 160 to 200 g / L, and the preferred organic polymer concentration is 20 to 40 g / L.

[0049] 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.

[0050] <<Blowing>> Spinning (fibrillation of the spinning solution) 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-mentioned spinning is not particularly limited, but it is preferable to use a structure such as that 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.

[0051] 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.

[0052] 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.

[0053] The basis weight of this thin sheet is preferably 10 to 300 g / m ２ , particularly preferably 30 to 200 g / m ２ To an extent, but not limited to this.

[0054] 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 (basis weight) of the laminated sheet becomes uniform throughout the sheet. As the above-mentioned folding device, the device described in JP 2000-80547 A can be used.

[0055] <Step of applying needling aid or antifriction agent> If necessary, a needling aid or antifriction agent is applied to the sheet surface of the thin sheet or laminated sheet of the alumina / silica-based inorganic fiber precursor obtained by spinning. The needling aid or antifriction agent is preferably applied to both sheet surfaces.

[0056] 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 agents, for example, acrylic polymer coating agents, can be used.

[0057] 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).

[0058] <Needling Treatment Step> A needling aid and / or an antifriction agent is applied as needed to the laminated sheet of alumina / silica-based inorganic fiber precursor obtained by spinning, and then the laminated sheet 9 is subjected to a needling treatment in which needles 7 having barbs 8 are inserted and removed from the laminated sheet 9, as shown in Fig. 5. 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.

[0059] 5, the needles 7 are preferably inserted and withdrawn in a direction perpendicular to the sheet surface of the laminated sheet 9. The needles are preferably inserted so as to penetrate the laminated sheet in the thickness direction.

[0060] In this way, needle penetration marks are formed in the inorganic fiber blanket by the needling process. 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 in the approximate thickness direction by the needles at the locations where the needles are pierced and removed. This forms needle penetration marks on the surface of the inorganic fiber blanket. Inside the inorganic fiber blanket that has been subjected to the needling process, the inorganic fiber threads extending in the approximate thickness direction are called warp threads.

[0061] The needling treatment is carried out to adjust the bulk density and peel strength of the inorganic fiber blanket by forming warp threads.

[0062] <Firing step> The inorganic fiber blanket is preferably a fired body obtained by firing a needling-treated inorganic fiber precursor. Firing is usually performed at a temperature of 900°C or higher, preferably 1000 to 1300°C. A firing temperature of 900°C or higher is preferred because crystallization proceeds sufficiently, resulting in alumina / silica-based fibers with excellent strength. A firing temperature of 1300°C or lower is also preferred because excessive grain growth of the fiber crystals does not proceed, resulting in alumina / silica-based fibers with appropriate strength.

[0063] The laminate of the present invention includes an inorganic fiber blanket and a substrate. The inorganic fiber blanket and the substrate may be simply stacked on top of each other, or may be bonded to each other with an adhesive or the like. The laminate of the present invention is preferably used as a battery pack cover that covers a battery pack.

[0064] [Substrate] The substrate to be laminated with the inorganic fiber blanket is not limited, and housing materials such as metal substrates and reinforced resin substrates can be used. From the viewpoint of flame resistance, metal substrates are preferred, and aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, titanium alloys, iron, stainless steel, etc. are suitable. If the laminate of the present invention has excellent flame resistance, it is suitable for use as a battery pack cover and is therefore preferred.

[0065] [Battery Pack Unit] The battery pack unit of the present invention includes a battery pack and a battery pack cover having an inorganic fiber blanket. FIGS. 1 and 2 are schematic cross-sectional views showing an example of a battery pack unit. This battery pack unit 1 includes a substrate (sometimes referred to as a battery pack cover substrate in a battery pack cover application) 2, a battery pack 3 disposed within the substrate 2, and an inorganic fiber blanket 4 disposed between the battery pack 3 and the substrate 2. The inorganic fiber blanket 4 and the substrate 2 are overlapped to form a battery pack cover 5. The two may be bonded together with an adhesive. The inorganic fiber blanket 4 is disposed inside the battery pack unit 1 relative to the substrate 2, but may also be disposed outside the substrate 2. The battery pack 3 includes multiple battery modules 6 or multiple individual battery cells 6. The inorganic fiber blanket 4 may be disposed so as to cover the entire surface of the pack 3, or may be disposed on only a portion of the pack 3. If disposed on only a portion of the pack 3, the location where it is disposed is not limited and may be on any one of the top, bottom, and / or side surfaces.

[0066] Fig. 1 shows an embodiment in which the battery pack cover 5 covers the entire surface of the battery pack 3. Fig. 2 shows an embodiment in which the battery pack cover 5 is placed on only a portion of the upper surface of the battery pack 3. In this embodiment, the battery pack cover 5 is placed on the vent portion (outlet) of the battery module 6 or the individual battery cell 6. In Fig. 2, the battery pack cover base material 2 and the portion S for storing the battery pack are separated.

[0067] This battery pack unit 1 can improve the flame-blocking properties of the battery pack cover without impairing loading capacity, and is therefore suitable for use as a battery for electric mobility such as electric vehicles, electric motorcycles, and ships. The battery is not limited to, and examples include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead-acid batteries, air batteries, and solid-state batteries. Of these, lithium-ion batteries are preferred.

[0068] [Example 1] <Production of inorganic fiber blanket> Silica sol was added to an aqueous solution of basic aluminum chloride (aluminum content 165 g / L, Al / Cl=1.8 (atomic ratio)), and the composition of the finally obtained alumina fiber was Al 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.

[0069] 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).

[0070] 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.

[0071] The basis weight can be changed by changing the number of times the fiber precursor is folded by the stacking device.

[0072] The mat-like aggregate of alumina / silica-based fiber precursor obtained by spinning was subjected to a needling treatment using needles 7, as shown in Figure 5. 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 9 of inorganic fiber precursor, the needles were needled so that they penetrated from one side to the other, so that a predetermined needle penetration mark density was achieved after firing, and so that an average of five barbs 8 per needle penetrated to the other side.

[0073] Then, it is fired at 1200°C and the basis weight is 600g / m ２ (Thickness 4.0 mm, bulk density 0.15 g / cm ３ ), needle penetration mark density 30.2 / cm ２ The sintering was carried out in an electric furnace by increasing 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.

[0074] 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 observing the inorganic fiber blanket with a microscope was 5.5 μm.

[0075] [Example 2] Needle penetration mark density: 13.7 marks / cm ２ The needling treatment and firing were carried out so that the basis weight was 600 g / m ２ , thickness 4.3 mm, bulk density 0.140 g / cm ３ An inorganic fiber blanket made of crystalline alumina / silica-based fibers was obtained in the same manner as in Example 1, except that the above-mentioned conditions were met.

[0076] [Example 3] Needle penetration mark density: 40.3 marks / cm ２ The needling treatment and firing were carried out so that the basis weight was 600 g / m ２ , thickness 4.1 mm, bulk density 0.146 g / cm ３An inorganic fiber blanket made of crystalline alumina / silica-based fibers was obtained in the same manner as in Example 1, except that the above-mentioned conditions were met.

[0077] [Example 4] In the needling treatment of Example 1, needling treatment and firing were carried out so that an average of four barbs penetrated the other surface, and the basis weight was 600 g / m ２ , thickness 4.0 mm, bulk density 0.150 g / cm ３ An inorganic fiber blanket made of crystalline alumina / silica-based fibers was obtained in the same manner as in Example 1, except that the above-mentioned conditions were met.

[0078] [Example 5] Needle penetration mark density: 30.2 marks / cm ２ , basis weight 700 g / m ２ The number of layers was changed, and needling and firing were performed to obtain a thickness of 4.5 mm and a bulk density of 0.156 g / cm ３ An inorganic fiber blanket made of crystalline alumina / silica-based fibers was obtained in the same manner as in Example 1, except that the above-mentioned conditions were met.

[0079] [Example 6] Needle penetration mark density: 30.2 marks / cm ２ , basis weight 500 g / m ２ The number of layers was changed, and needling and firing were performed to obtain a thickness of 3.7 mm and a bulk density of 0.135 g / cm. ３ An inorganic fiber blanket made of crystalline alumina / silica-based fibers was obtained in the same manner as in Example 1, except that the above-mentioned conditions were met.

[0080] [Comparative Example 1] In the needling treatment of Example 1, the needles were pierced so that the number of barbs piercing to the other surface was one per needle on average, and the needle penetration mark density was 6.8 / cm ２ The needling treatment and firing were carried out so that the basis weight was 600 g / m ２ , thickness 5.3 mm, bulk density 0.113 g / cm ３ An inorganic fiber blanket made of crystalline alumina / silica-based fibers was obtained in the same manner as in Example 1, except that the above-mentioned conditions were met.

[0081] <<Measurement of Physical Properties of Inorganic Fiber Blanket>> For each of the inorganic fiber blankets obtained in the above examples and comparative examples, the peel strength and needle penetration mark density were measured by the methods described above, and the tensile strength and thickness were also measured and a flame test was performed as follows. The results are shown in Table 1.

[0082] Peel strength was measured using a tensile tester. The effective size of the test piece was 50 × 75 mm, and a slit was made in the thickness center of one end on the 50 mm width side to a length of 25 mm, and both ends formed by the slit were gripped and attached to the tensile tester, and pulled at a speed of 100 mm / min. The maximum load was defined as the peel strength.

[0083] Tensile strength was measured using a tensile tester. The parallel portion (effective portion) of the test piece was 25 mm x 100 mm, and the overall size was 25 mm x 160 mm. Each inorganic fiber blanket in the finished state was cut to the above size using a punching die, attached to the tensile tester, and pulled at a rate of 25 mm / min. The maximum load was defined as the tensile strength.

[0084] Thickness measurement method: The thickness was measured using a digital dial gauge. The measurement load was 4.9 kPa (50 g / cm ２ ) and the minimum measurement scale is 0.01 mm. The thickness of a test piece cut out by the method described in the flame test method described below was measured at five random points using the measuring jig, and the average value of the five points was used as the representative value of the measurement.

[0085] Flame test method: The inorganic fiber blankets of Examples 1 to 6 and Comparative Example 1 were cut into 3600 mm pieces using a punching die. ２ The cut inorganic fiber blanket was cut into the size of each aluminum alloy plate (3600 mm ２ The test piece was prepared by stacking a sheet of the laminated sheet (0.8 mm thick) on a sheet of the laminated sheet (0.8 mm thick) and subjected to the following flame test.

[0086] The test specimen was clamped and fixed in a stainless steel jig and placed 70 mm away from the tip of the torch burner with the inorganic fiber blanket side facing the burner and the matte surface of the inorganic fiber blanket approximately perpendicular to the axial direction of the burner.

[0087] This torch burner (Sakaguchi Manufacturing Co., Ltd.: WT-01, nozzle diameter 1.2 mm) ２ 0.50 MPa, C ２ H ２ A flame was supplied from an air nozzle at 0.02 MPa and an air pressure of 0.24 MPa (discharge nozzle diameter 3.0 mm, positioned 40 mm away from the test piece so that the mat surface of the inorganic fiber blanket was approximately perpendicular to the axial direction of the air nozzle) for 30 minutes, and a flame with a temperature of 1000°C and air at a speed of 100 m / s was sprayed toward the test piece for 10 seconds every 2 minutes, up to 15 times.

[0088] The test specimen was removed 30 minutes and 30 seconds after the start of the flame injection toward the inorganic fiber blanket of the test specimen, and it was visually confirmed whether or not the inorganic fiber blanket had been penetrated. If penetration by air (or flame) occurred during the test, the test specimen was removed at the time of penetration, and the number of air injections until penetration occurred was defined as the flame test durability cycle.

[0089]

[0090] <Considerations> As shown in Table 1, the inorganic fiber blanket of the present invention has a high flame test durability and is excellent in flame barrier properties, even though it is thin.

[0091] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese Patent Application No. 2021-188751, filed on November 19, 2021, and is incorporated by reference in its entirety.

[0092] REFERENCE SIGNS LIST 1 Battery pack unit 2 Base material (battery pack cover base material) 3 Battery pack 4 Inorganic fiber blanket 5 Battery pack cover 5' Battery pack cover 6 Battery module 7 Needle 8 Barb 9 Laminated sheet 11 Inorganic fiber blanket test piece 12 Grip jig

Claims

1. Basis weight 700g / m ２ and a bulk density of 0.125 g / cm ３ An inorganic fiber blanket comprising the above needle blanket.

2. The needle blanket has needle penetration marks penetrating from one surface to the other surface, and the density of needle penetration marks is 35 pcs / cm ２ The inorganic fiber blanket according to claim 1, wherein:

3. Basis weight 700g / m ２ and a bulk density of 0.125 g / cm ３ The inorganic fiber blanket described above is characterized in that it is not penetrated for 5 minutes in a flame test at a flame temperature of 1000°C and an air jet speed of 100 m / s, using a laminate consisting of the inorganic fiber blanket and an aluminum alloy plate having a thickness of 0.8 mm as a test piece.

4. The inorganic fiber blanket according to any one of claims 1 to 3, having a peel strength of 4.0 N or more as determined by the following method. <Method for measuring peel strength> Measured using a tensile tester. The effective size of the test piece is 50 x 75 mm. A slit is made in the center of the thickness of one end of the 50 mm width side, extending 25 mm in the longitudinal direction. Both ends formed by the cut are gripped and attached to a tensile tester, and the specimen is pulled at a speed of 100 mm / min. The maximum load is defined as the peel strength.

5. A laminate comprising the inorganic fiber blanket according to any one of claims 1 to 3 and a substrate.

6. The laminate according to claim 5 , wherein the substrate is a metal substrate.

7. 7. The laminate according to claim 6, wherein the metal is aluminum, an aluminum alloy, magnesium, a magnesium alloy, titanium, a titanium alloy, iron, or stainless steel.

8. The laminate according to claim 5 , which is used as a battery pack cover.

9. A battery pack unit comprising the inorganic fiber blanket according to any one of claims 1 to 3.

10. A battery pack unit comprising the laminate according to claim 8 and a battery pack, A battery pack unit in which the inorganic fiber blanket of the laminate is disposed on the battery pack side

11. A battery pack unit comprising the laminate according to claim 8 and a battery pack, A battery pack unit in which the base material of the laminate is disposed on the battery pack side relative to the inorganic fiber blanket.

12. An electric mobility device comprising the battery pack unit according to claim 9.