Thin fire-resistant sheet having excellent flame-blocking and fire-resistance properties for electric vehicle battery, and manufacturing method thereof

Abstract

A fire-resistant sheet for an electric vehicle battery according to an embodiment of the present invention comprises: a flame-blocking layer for blocking direct heat transfer from the flame; and a fire-resistant adhesive layer laminated on the flame-blocking layer, the fire-resistant adhesive layer comprising synthetic resin, thermal expansion material, a phosphorus-based flame retardant, and fire-resistant inorganic material.

Description

A fire-resistant sheet for a thin electric vehicle battery with excellent flame blocking and fire resistance performance and a method for manufacturing the same

[0001] The present invention relates to a technology for refractory materials for electric vehicle batteries, and more specifically, to a refractory sheet for a thin electric vehicle battery, which improves flame blocking and fire resistance performance by laminating a refractory adhesive layer containing a heat-expandable material in a synthetic resin to a flame blocking layer, and a method for manufacturing the same.

[0002]

[0003] The secondary battery market has been growing rapidly with the recent expansion of electric vehicles. However, fires caused by thermal runaway in batteries are frequently causing casualties and property damage. To address this issue, various fire-resistant materials are being developed. Conventional methods typically involve the use of flame-retardant adhesives to secure refractory materials, seal gaps, prevent heat dissipation, and prevent the ingress of foreign substances.

[0004]

[0005] However, existing flame retardants each have the following limitations. First, halogenated flame retardants such as Br and Cl exhibit excellent flame retardancy, but their use is restricted due to their environmental hazards and are subject to international regulations. Phosphorous and inorganic flame retardants, which are intended to replace them, have significantly lower flame retardancy compared to halogenated flame retardants. Therefore, to achieve comparable flame retardancy, the flame retardant ratio must be increased. This not only increases manufacturing costs, but also causes problems such as easy peeling and reduced fixation.

[0006]

[0007] Meanwhile, attempts have been made to apply thermally expandable layered inorganic materials to refractory laminates and battery materials. This method offers significant improvements in flame retardancy, excellent fire retardancy due to the expansion-induced void closure, and the ability to withstand temperatures as high as approximately 3600°C. However, this method also struggles to achieve complete shielding due to the graphite dust generated after expansion. This dust can also cause malfunctions in advanced products and mechanical failures, limiting its use as a heat-insulating sealing material. Furthermore, the increased thickness of adhesives or tapes due to graphite increases production costs.

[0008]

[0009] Therefore, there is a need to develop new refractory materials that can solve the above problems.

[0010]

[0011] The present invention is intended to solve the above-described problems, and proposes a refractory material for a thin electric vehicle battery having excellent flame blocking and fire resistance performance, and a method for manufacturing the same.

[0012] However, the technical tasks that this embodiment seeks to accomplish are not limited to the technical tasks described above, and other technical tasks may exist.

[0013]

[0014] A fire-resistant sheet for an electric vehicle battery according to one embodiment of the present invention comprises a flame-blocking layer that blocks direct heat transfer from a flame and a fire-resistant adhesive layer laminated on the flame-blocking layer, wherein the fire-resistant adhesive layer comprises a synthetic resin, a heat-expanding material, a phosphorus flame retardant, and a fire-resistant inorganic material.

[0015] In addition, the flame blocking layer is characterized by being one selected from among mica sheet, metal sheet, silica sheet, alumina sheet, glass fiber, flame retardant nonwoven fabric, refractory fiber, carbon fiber, and combinations thereof.

[0016] In addition, the refractory inorganic material is characterized by being any one selected from yellow soil, bentonite, kaolin, aluminum hydroxide, aluminum oxide, alumina trihydrate (ATH), magnesium hydroxide, zinc oxide, magnesium oxide, and combinations thereof.

[0017] In addition, the synthetic resin is any one selected from among acrylic resin, epoxy resin, polyvinyl acetal resin, polyvinyl chloride resin, polyolefin resin, and combinations thereof, and the acrylic resin is any one selected from among polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polybutylacrylate (PBA), polymethyl acrylate (PMA), acrylic copolymer, and combinations thereof.

[0018] In addition, the thermal expansion material is characterized by being one selected from expandable graphite, vermiculite, perlite, expandable mica, and a combination thereof.

[0019] In addition, the content ratio of the refractory adhesive layer is characterized in that it includes 40 to 70 parts by weight of the synthetic resin, 5 to 15 parts by weight of the phosphorus flame retardant, 5 to 20 parts by weight of the refractory inorganic material, 10 to 20 parts by weight of the thermal expansion material, and the remaining amount of additives, based on 100 parts by weight of the total refractory adhesive layer.

[0020] In addition, the fire-resistant adhesive layer is characterized in that the combined weight of the phosphorus flame retardant, the fire-resistant inorganic material, and the thermal expansion material is 45 parts by weight or less, based on 100 parts by weight of the total of the fire-resistant adhesive layer.

[0021] In addition, the thickness of the flame blocking layer is 50 to 1000 μm, and the thickness of the fire-resistant adhesive layer is 40 to 1300 μm.

[0022] In addition, the above-mentioned fire-resistant adhesive layer is characterized by having an adhesive strength of 400 gf / 25 mm or more measured based on ASTM D3330 while satisfying the UL94 V-0 flame retardancy rating.

[0023] In addition, the fire-resistant sheet for the electric vehicle battery is characterized in that it is attached to any one part selected from the following: a pressure pad between battery cells, a module cover covering the outside of a battery module, an inner surface of a battery pack in which a battery module is stored, a battery pack cover covering the outside of a battery pack, a gap between battery modules, a cover for protecting electrical wiring inside a battery pack, and a combination thereof.

[0024]

[0025] In addition, a method for manufacturing a fire-resistant sheet for an electric vehicle battery according to one embodiment of the present invention includes a step of preparing a flame-blocking layer that blocks direct heat transfer from a flame, a step of preparing a fire-resistant adhesive layer laminated on the flame-blocking layer, and a step of bonding the flame-blocking layer and the fire-resistant adhesive layer to each other, wherein the fire-resistant adhesive layer is characterized in that it includes a synthetic resin, a heat-expandable material, a phosphorus-based flame retardant, and a fire-resistant inorganic material.

[0026]

[0027] The fire-resistant sheet for an electric vehicle battery according to the present invention can simultaneously achieve excellent flame blocking performance and fire resistance despite its thin thickness.

[0028] In addition, it provides excellent initial adhesion while maintaining a thin thickness, enabling stable attachment. Due to these characteristics, it can be widely applied to various parts of an electric vehicle battery system, such as the contact pressure pad between battery cells, battery module cover, and battery pack cover.

[0029] Additionally, the tape does not burn out even when exposed to high temperatures, providing a continuous fire prevention effect, which means that it can perform a stable fire spread prevention function even in a thermal runaway situation of the battery.

[0030] Additionally, the manufacturing process can be simplified compared to existing refractory materials, which can improve productivity and reduce costs.

[0031] However, the effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the attached drawings.

[0032]

[0033] FIGS. 1 to 3 are drawings for explaining a refractory sheet for an electric vehicle battery according to one embodiment of the present invention.

[0034] FIG. 4 is a drawing showing a photo of the results of a fire resistance test of a fire-resistant sheet for an electric vehicle battery according to one embodiment of the present invention.

[0035]

[0036] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention will be able to easily propose other inventions that are retrograde or other embodiments included within the scope of the spirit of the present invention by adding, modifying, or deleting other components within the scope of the same spirit. However, this will also be considered to be included within the scope of the spirit of the present invention.

[0037] Additionally, the terminology used herein is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. Throughout the specification of the present invention, the term "including" or "comprising" a component does not exclude other components, but rather implies the inclusion of other components, unless specifically stated otherwise. The present invention will be described in detail below.

[0038]

[0039] FIGS. 1 to 3 are drawings for explaining a refractory sheet for an electric vehicle battery according to one embodiment of the present invention.

[0040]

[0041] Referring to FIGS. 1 to 3, a fire-resistant sheet for an electric vehicle battery according to one embodiment of the present invention includes a flame-blocking layer (10) and a fire-resistant adhesive layer (20). At this time, the fire-resistant sheet for an electric vehicle battery is characterized in that the fire-resistant adhesive layer (20) is not lost even under a predetermined temperature condition, and the fire-resistant sheet satisfies the V-0 grade of the UL94 test while having excellent adhesive strength, flame retardancy, and fire resistance, and can be manufactured with a thin thickness.

[0042] Accordingly, the fire-resistant sheet for the electric vehicle battery can be attached to any one part selected from the pressure pad between battery cells, the module cover covering the outside of the battery module, the inner surface of the battery pack in which the battery module is stored, the battery pack cover covering the outside of the battery pack, the gap between battery modules, the cover for protecting the electrical wiring inside the battery pack, and a combination thereof, and is not limited thereto, and can be modified in various ways at a level obvious to a person skilled in the art.

[0043] For example, the fire-resistant sheet of the present invention can be utilized in various industrial fields in addition to its main use in electric vehicle battery systems, and for example, it can be applied around electrical wiring or communication cables in general buildings to prevent the spread of fire, and in particular, it can provide effective fire safety when applied to wiring ducts or cable trays in multi-use facilities, and in industrial facilities, it can be used as an insulation material for high-temperature pipelines or boiler systems, and can also be utilized as a firewall reinforcement material in flammable material storage facilities or hazardous material handling areas in chemical plants. In particular, the fire-resistant sheet of the present invention can be utilized to secure the fire safety of important equipment in IT infrastructure facilities such as the fire-resistant treatment of high-temperature equipment in semiconductor manufacturing processes, clean rooms, and server rooms or communication equipment rooms in data centers.

[0044] In addition, the fire-resistant sheet of the present invention may be in a form in which a fire-resistant adhesive layer (20) is laminated on one side of a flame-blocking layer (10), but is not limited thereto and can be modified in various ways at a level obvious to a person skilled in the art.

[0045] For example, the fire-resistant sheet may have a fire-resistant adhesive layer (20) laminated on both sides of the fire-resistant adhesive layer (10), and the fire-resistant layer (10) may be laminated on both sides of the fire-resistant adhesive layer (20). In addition, the fire-resistant sheet may have a fire-resistant layer (10) positioned on each of the outermost layers so that the fire-resistant layer (10) and the fire-resistant adhesive layer (20) may be laminated in a cross-like manner in a plurality of layers, and the fire-resistant adhesive layer (20) may be positioned on each of the outermost layers so that the fire-resistant layer (10) and the fire-resistant adhesive layer (20) may be laminated in a cross-like manner in a plurality of layers.

[0046]

[0047] The flame blocking layer (10) of the present invention is configured to block direct heat transfer from internal and external flames, and the flame blocking layer (10) may be any one selected from among mica sheets, metal sheets, silica sheets, alumina sheets, glass fibers, flame-retardant nonwoven fabrics, refractory fibers, carbon fibers, and combinations thereof. Preferably, a mica sheet may be used, but the present invention is not limited thereto.

[0048] For example, a mica sheet used as a flame barrier layer (10) can be composed of flaky particles obtained by exfoliating mica, a glass fiber substrate, and a silicone-based binder for binding them. The most notable characteristic of the mica sheet is that it has a layered silicate structure, which has a hexagonal plate-shaped crystal structure as its base and a form in which an exfoliation layer having a thickness of 0.1 to 1 μm is laminated. Due to this structural characteristic, the mica sheet can simultaneously secure excellent heat resistance and insulation.

[0049] For example, mica sheets have a high heat-resistant temperature of 900 to 1000℃ and a low thermal conductivity of 0.30 to 0.5 W / mK. In addition, they have a thermal expansion coefficient of 8 to 12 * 10^-6 / K, which provides excellent resistance to thermal shock. These thermal properties play a very important role in the thermal runaway situation of electric vehicle batteries. In particular, the layered structure delays heat transfer, the formation of a fine air layer maximizes the insulation effect, and the thermal energy can be effectively dispersed and absorbed.

[0050] Furthermore, in terms of electrical properties, mica sheets exhibit a high breakdown voltage of 1520 kV / mm and a volume resistivity of 10^15 to 10^16 Ω·cm, which can be very effective in preventing electrical short-circuits and blocking the propagation of thermal runaway. In addition, a dielectric constant of 5 to 7 (based on 1 MHz) and a low dielectric loss tangent of 0.0001 to 0.001 can also provide an electromagnetic shielding effect.

[0051] For example, the manufacturing of mica sheets can be comprised of the steps of exfoliation, shaping, and post-processing of mica.

[0052] First, the exfoliation process appropriately combines mechanical and chemical exfoliation of natural mica to obtain mica particles with a uniform particle size distribution. Mechanical exfoliation uses shear force to physically separate mica crystals, while chemical exfoliation involves inserting a specific substance between the layers to cause swelling. By appropriately combining these two methods, an optimized interlayer spacing in the range of 0.1 to 1 μm can be achieved.

[0053] At this time, optimizing the interlayer spacing is a key factor in determining product performance. If the spacing is too narrow, heat transfer can occur rapidly, degrading insulation performance. Conversely, if the spacing is excessively wide, mechanical strength can be reduced and handling can be compromised. Therefore, precise control of the interlayer spacing can be crucial during the peeling process.

[0054] Next, in the molding process, the exfoliated mica particles are molded into sheets together with a glass fiber substrate. To prevent uneven interlayer spacing during the re-lamination process of the mica particles, the viscosity and application amount of the binder are precisely controlled. If necessary, additional shear force can be applied to ensure uniform interlayer alignment. Wet or dry molding methods can be selectively employed, allowing for controlled dimensional stability and density of the product.

[0055] Finally, post-processing involves heat treatment to harden the binder and surface treatment to enhance moisture resistance. During this process, it is crucial to maintain a uniform interlayer spacing while ensuring appropriate mechanical strength and heat resistance. In particular, controlling the heat treatment temperature and time optimizes the degree of crosslinking of the binder, thereby improving the physical properties of the final product.

[0056] Mica sheets manufactured through this manufacturing process exhibit excellent heat resistance and insulation, significantly improving the fire safety of electric vehicle batteries. Specifically, by optimizing the interlayer spacing, the material effectively delays heat transfer while simultaneously ensuring adequate mechanical strength, maximizing its performance as a fire-resistant material.

[0057] In the present invention, by using a mica sheet having such excellent characteristics as a flame-blocking layer (10), the fire safety of an electric vehicle battery can be greatly improved, and in particular, by combining it with a fire-resistant adhesive layer (20), the fire prevention performance can be further maximized, which can greatly contribute to improving the overall safety of an electric vehicle battery system.

[0058] In addition, the flame blocking layer (10) may have a thickness of 50 to 1000 μm, and when the thickness of the flame blocking layer (10) is less than 50 μm, the mechanical strength against external impact is weak, so it may be easily damaged, and it is difficult to effectively block flame and heat when thermal runaway occurs. In addition, the durability is reduced due to the thin thickness, so it is difficult to secure long-term reliability, and there is a problem that wrinkles or tears easily occur during product handling. For example, when the flame blocking layer (10) is a mica sheet, it is difficult to sufficiently implement the layered structure of the mica sheet, so the heat blocking performance may be significantly reduced. In addition, the mica sheet may be easily broken or cracked during the lamination process with the refractory adhesive layer (20), and the adhesive of the refractory adhesive layer (20) may excessively penetrate between the layers of the mica sheet, making it difficult to exhibit the original heat blocking performance.

[0059] On the other hand, if the thickness of the flame barrier layer (10) exceeds 1000 μm, the flexibility of the product is significantly reduced, making it difficult to install it on curved or stepped parts of the electric vehicle battery system. In addition, excessive thickness may cause an increase in the overall volume of the electric vehicle battery system, which may lead to an increase in manufacturing costs due to an increase in material costs. In particular, there are disadvantages such as reduced workability during post-processing and an increase in the weight of the product, making handling inconvenient. For example, if the flame barrier layer (10) is a mica sheet, delamination between layers of the mica sheet may easily occur, and the interfacial bonding strength with the fire-resistant adhesive layer (20) may be reduced. In particular, when exposed to high temperatures, delamination may become more severe, rapidly reducing the fire-blocking performance, and thermal stress may occur due to a difference in thickness with the fire-resistant adhesive layer (20), which may cause the bonding state to become unstable. In addition, excessive thickness of the mica sheet may cause the adhesive strength of the fire-resistant adhesive layer (20) to not be sufficiently developed.

[0060] Additionally, a metal sheet may be used as the flame-blocking layer (10) of the present invention, which can serve as another form of fire prevention solution that replaces or supplements mica sheets. The metal sheet, based on the inherent non-combustibility and excellent heat resistance of metal, can serve as an effective fire-blocking barrier in the event of a fire.

[0061] For example, the metal sheet may include stainless steel (SUS), Invar, and a super heat-resistant alloy.

[0062] For example, stainless steel is an iron-based alloy containing 10.5% or more chromium (Cr), and has excellent corrosion resistance and heat resistance, as well as excellent mechanical strength. In particular, austenitic stainless steel such as SUS 304 or SUS 316 has excellent stability at high temperatures, making it suitable as a material for fire prevention.

[0063] For example, Invar, a 36% nickel-iron alloy, features a very low coefficient of thermal expansion (approximately 1.2*10^-6 / K). This low thermal expansion minimizes thermal deformation during a fire, resulting in excellent dimensional stability, which can be a key factor in enhancing the reliability of fire-resistant performance.

[0064] For example, when even more extreme high-temperature stability is required, superalloys can be applied. Nickel-chromium-based superalloys maintain stable mechanical properties up to approximately 1000°C and form a dense oxide film at high temperatures, preventing further oxidation. Cobalt-based superalloys maintain stable properties up to approximately 1100°C and, with their particularly excellent thermal fatigue resistance, can maintain stable performance even after repeated thermal shock.

[0065] Additionally, the thickness of the metal sheet should be optimized considering fire-blocking performance and practical applicability. Typically, a thickness in the range of 50 to 200 μm can be applied. If the thickness is too thin, mechanical strength and fire-blocking performance may be degraded, while if it is too thick, weight increases and flexibility decreases, making practical application difficult.

[0066] In addition, the surface of the metal sheet may require surface treatment to improve adhesion with the fire-resistant adhesive layer (20). For example, the surface roughness may be increased or the surface energy may be adjusted through chemical etching, sandblasting, corona treatment, etc., and the adhesion may be further improved through primer treatment if necessary. In particular, since the metal sheet is electrically conductive, an appropriate insulation design may be required when applied to an electric vehicle battery system. To this end, electrical safety can be secured by applying an insulation coating to the surface of the metal sheet or by designing a fire-resistant adhesive layer (20) with insulating properties. When the metal sheet is used as a flame barrier layer (10), excellent mechanical strength, dimensional stability, and highly reliable fire-blocking performance can be obtained, which can contribute to further improving the safety of the electric vehicle battery.

[0067] However, without limitation thereto, the flame blocking layer (10) can be modified in various ways at a level obvious to a person skilled in the art.

[0068]

[0069] The fire-resistant adhesive layer (20) of the present invention is a key component that provides the adhesive strength of the flame-blocking layer (10) while also providing additional flame-retardant performance in the event of a fire. At this time, an essential characteristic of the fire-resistant adhesive layer (20) is that it should not be lost even at a predetermined temperature and should maintain adhesive strength. This may be to prevent the fire-resistant sheet for electric vehicle batteries from losing adhesive strength and detaching from the attachment due to flame.

[0070] For example, the fire-resistant adhesive layer (20) may include synthetic resin, thermal expansion material, phosphorus flame retardant, and fire-resistant inorganic material as main components. At this time, the synthetic resin may be any one selected from acrylic resin, epoxy resin, polyvinyl acetal resin, polyvinyl chloride resin, polyolefin resin, and combinations thereof, and preferably may be an acrylic resin, and the acrylic resin may be any one selected from polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polybutyl acrylate (PBA), polymethyl acrylate (PMA), acrylic copolymer, and combinations thereof. However, the present invention is not limited thereto, and various modifications may be made at a level obvious to those skilled in the art.

[0071] Here, the acrylic resin used in the refractory adhesive layer (20) of the present invention is a component that provides excellent adhesive properties and durability. For example, polybutylacrylate (PBA) has a low glass transition temperature (Tg) due to its flexible butyl group, resulting in excellent flexibility and initial adhesive strength at room temperature. These properties enable it to provide high adhesiveness to various adherends, and in particular, it has the advantage of maintaining adhesive strength even at low temperatures. On the other hand, polymethyl methacrylate (PMMA) has a high glass transition temperature and excellent heat resistance and mechanical strength due to the dense molecular structure of methyl methacrylate. These properties significantly contribute to improving stability at high temperatures. For example, polyethyl acrylate (PEA) exhibits intermediate properties between PBA and PMMA due to the appropriate chain length of the ethyl group, and can achieve a balance of adhesion and heat resistance, while polymethyl acrylate (PMA) has excellent weather resistance and durability due to the stability of the methyl group, ensuring long-term reliability, and is particularly excellent in resistance to ultraviolet rays and oxidation.

[0072] These acrylic resins possess excellent affinity for various substrates, such as metals and plastics, due to the polar groups, such as carboxyl and hydroxyl groups, within their molecular structures. Furthermore, these polar groups can physically and chemically interact with other components of the present invention, such as thermal expansion agents, refractory inorganic materials, and phosphorus flame retardants, thereby forming stable complexes.

[0073] In particular, in the fire-resistant adhesive layer (20) of the present invention, it may be more preferable to use an acrylic copolymer rather than an acrylic monomer, because the acrylic copolymer can utilize the advantages of each monomer and compensate for its disadvantages through a combination of different monomers, thereby optimizing various physical properties required for the fire-resistant adhesive layer (20).

[0074] For example, in the case of poly(n-butyl acrylate-co-methyl methacrylate), which is a copolymer of n-butyl acrylate and methyl methacrylate, the n-butyl acrylate monomer provides adhesion and flexibility at room temperature due to its low glass transition temperature, and the methyl methacrylate monomer can improve heat resistance and mechanical strength due to its high glass transition temperature and dense structure.

[0075] In addition, poly(2-ethylhexyl acrylate-co-acrylic acid), a copolymer of 2-ethylhexyl acrylate and acrylic acid, has excellent adhesive properties provided by 2-ethylhexyl acrylate, and due to the carboxyl group (-COOH) of acrylic acid, adhesion to the adherend can be improved and compatibility with additives can also be improved.

[0076] In addition, a terpolymer such as poly(2-ethylhexyl acrylate-co-acrylic acid-co-2-hydroxyethyl methacrylate) can be formed by increasing the content of acrylic acid or introducing a monomer containing a hydroxyl group (-OH), such as 2-hydroxyethyl methacrylate. These polar groups can improve the dispersibility of the particles through physical and chemical interactions with the additive particles and contribute to maintaining a stable complex structure even at high temperatures. In particular, by controlling the molecular weight and molecular weight distribution of the acrylic copolymer, the viscosity and flow characteristics of the refractory adhesive layer (20) can be optimized. An appropriate molecular weight is important for securing processability along with sufficient mechanical strength, and the molecular weight distribution affects the initial adhesion and long-term adhesion stability of the adhesive. In addition, by controlling the degree of crosslinking of the copolymer, the dimensional stability and solvent resistance at high temperatures can be improved.

[0077] Through the molecular design of this acrylic copolymer, the fire-resistant adhesive layer (20) can effectively implement the flame retardant performance required in case of fire along with excellent adhesive properties. In particular, in the present invention, by optimizing the composition and structure of the acrylic copolymer, a stable fire-resistant adhesive layer can be implemented that does not delaminate or lose layers even at high temperatures of 300°C or higher, and has excellent compatibility with other components of the present invention, and a stable fire-resistant adhesive layer in which these additives are uniformly dispersed can be formed.

[0078]

[0079] In addition, the thermal expansion material, which is one of the main components of the fire-resistant adhesive layer (20) of the present invention, can form an insulating layer and provide an oxygen blocking effect through rapid volume expansion when a fire occurs. For example, the thermal expansion material may be any one selected from expandable graphite, vermiculite, perlite, expandable mica, and a combination thereof, and preferably expandable graphite, but is not limited thereto, and may be modified in various ways at a level obvious to a person skilled in the art.

[0080] For example, expanded graphite is manufactured by injecting an intercalating agent, such as sulfuric acid, between graphite layers. When exposed to temperatures above 200°C, the intercalating agent decomposes, releasing gases that cause the interlayers of the graphite to rapidly expand. This expansion process can expand up to 100 to 300 times its original volume, and the resulting worm-shaped porous structure provides excellent insulation and oxygen barrier properties.

[0081] For example, vermiculite exhibits the characteristic of expanding in volume as the water of crystallization between its layers evaporates during a fire. Perlite can form a porous structure as pearlite foams at high temperatures. Expanded mica can also exhibit the characteristic of expanding in volume as the moisture present between its layers evaporates at high temperatures.

[0082] These thermal expansion agents must be dispersed in an appropriate size within the acrylic copolymer matrix. If the particle size is too small, the expansion effect will be reduced, and if it is too large, the uniformity of the adhesive layer may be reduced. Therefore, it is important to optimize the particle size distribution of the thermal expansion agent, and if necessary, the compatibility with the acrylic copolymer can be improved through surface treatment. In particular, in the present invention, by optimizing the content and particle size distribution of the thermal expansion agent, uniform expansion occurs throughout the fire-resistant adhesive layer (20) when a fire occurs. Through this, it is possible to form an effective insulation layer while preventing the detachment of the flame barrier layer (10), and excellent fire prevention performance can be realized through a synergistic effect with other flame retardant components. In addition, the thermal expansion agent also has a complementary effect with other additives such as yellow clay and phosphorus-based flame retardants. For example, the porous structure formed during expansion can promote the ceramicization of yellow clay and contribute to stabilizing the formation of a char layer of a phosphorus-based flame retardant. Through these complex actions, stable flame retardant performance can be achieved even at high temperatures exceeding 300℃.

[0083] For example, in the present invention, expanded graphite may be adopted as a thermal expansion material, wherein the expanded graphite has a worm-shaped porous structure formed by expanding when heat is applied, which can physically block the diffusion of oxygen and delay heat transfer.

[0084] For example, when a fire occurs, expanded graphite can rapidly expand due to the gas generated when an intercalant, such as sulfuric acid, inserted between the layers of the expanded graphite decomposes at a temperature of 200°C or higher. At this time, the formed worm-shaped porous structure can form a physical barrier within the refractory adhesive layer (20), blocking the inflow of oxygen and hindering heat transfer. In addition, as the expanded graphite expands, the volume of the refractory adhesive layer (20) increases, which effectively seals the area where a fire occurred, and in particular, can be very effective in preventing the spread of fire through gaps or gaps in an electric vehicle battery system. Furthermore, the porous structure of expanded graphite contains many air layers inside, which can provide excellent insulation performance, and this insulation effect can contribute to inhibiting the spread of fire by delaying heat transfer, and the refractory structure of expanded graphite can form a more solid firewall by acting complementarily with the char layer formed by the phosphorus flame retardant, and can provide structural stability even during the ceramicization process of yellow clay.

[0085] Due to the action of this expanded graphite, the refractory adhesive layer (20) of the present invention can exhibit active fire prevention performance beyond a simple adhesive function, which can greatly improve the safety of electric vehicle batteries.

[0086] At this time, the particle size of the expanded graphite may be 30 to 270 μm, and when the particle size of the expanded graphite is less than 30 μm, the particle size is too small to obtain the expected expansion effect when a fire occurs, and the volume of the porous structure formed after expansion is not sufficient, so that the oxygen blocking and insulation effects may be significantly reduced. In addition, fine particles are easily aggregated within the acrylic copolymer matrix, and as a result, uniform expansion does not occur throughout the refractory adhesive layer (20), which may result in uneven fire prevention performance. On the other hand, when the particle size of the expanded graphite exceeds 270 μm, the uniformity of the refractory adhesive layer (20) may be deteriorated and the adhesive strength may be reduced due to large particles. In particular, in a situation where the thickness of the refractory adhesive layer (20) is limited, excessively large expanded graphite particles may cause structural instability within the layer, which may cause delamination between layers during long-term storage or use. In addition, large particles are easily exposed to the surface, which reduces the smoothness of the refractory adhesive layer (20), which may cause a decrease in the adhesive strength with the adherend.

[0087]

[0088] In addition, the phosphorus-based flame retardant used in the fire-resistant adhesive layer (20) of the present invention is an environmentally friendly flame retardant that exhibits a flame retardant effect by forming a carbonized layer through a dehydration and carbonization action during thermal decomposition. Unlike halogen-based flame retardants, the phosphorus-based flame retardant does not generate harmful gases when burned, and has the advantage of not lowering the physical properties of the fire-resistant adhesive layer (20) due to its excellent compatibility with acrylic copolymers. At this time, the phosphorus-based flame retardant that can be used in the present invention can be broadly classified into three types.

[0089] For example, low-molecular-weight phosphorus compounds may include aluminum diethylphosphinate, aluminum hypophosphite, and ammonium polyphosphate. In particular, aluminum diethylphosphinate has excellent thermal stability and does not decompose during processing, and can exhibit effective flame retardant performance at high temperatures of 300°C or higher. This can suppress combustion in the gas phase by forming radicals containing phosphorus during thermal decomposition, and at the same time, form a dense carbon layer to provide an oxygen and heat blocking effect.

[0090] For example, the phosphate ester series may include triphenyl phosphate, tricresyl phosphate, resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), etc., and these phosphate esters have a structure in which an organic group is bonded through oxygen centered on a P=O bond, and in particular, phosphate esters containing an aromatic structure may have excellent thermal stability and excellent compatibility with acrylic copolymers.

[0091] For example, phosphate polyesters are flame retardants in the form of polymers containing phosphoric acid groups within their molecular structure, and can be manufactured through the polymerization of a phosphorus-containing diol and a dicarboxylic acid, or a phosphorus-containing dicarboxylic acid and a diol. Due to their polymer structure, these phosphate polyesters have excellent heat resistance, excellent compatibility with acrylic copolymers, and can form an effective carbon layer upon thermal decomposition.

[0092] These phosphorus-based flame retardants can be used alone in the fire-resistant adhesive layer (20), but more effective flame retardant performance can be achieved by using two or more in combination. For example, when a low-molecular-weight phosphorus-based compound and a phosphoric acid ester are used together, the flame retardant mechanisms in the gas phase and the solid phase work complementarily to obtain a more excellent fire prevention effect. In addition, the phosphorus-based flame retardant also works effectively with other components of the fire-resistant adhesive layer (20). In particular, the carbonized layer formed within the expanded structure of the expanded graphite can form a more stable fire barrier and provide additional heat resistance during the ceramicization process of the yellow clay. Through these complex actions, the fire-resistant adhesive layer (20) of the present invention can exhibit excellent flame retardant performance.

[0093]

[0094] In addition, the refractory inorganic material used in the refractory adhesive layer (20) of the present invention is configured to prevent the loss of the refractory adhesive layer (20) in the event of a fire and provide structural stability while providing additional heat resistance. The refractory inorganic material may include yellow soil, bentonite, kaolin, aluminum hydroxide, aluminum oxide, alumina trihydrate (ATH), magnesium hydroxide, zinc oxide, magnesium oxide, etc., and these refractory inorganic materials may perform various roles in the refractory adhesive layer (20) depending on their respective characteristics.

[0095] For example, clay minerals such as yellow clay, bentonite, and kaolin can form a stable inorganic structure when ceramicized at high temperatures, thereby maintaining the structural stability of the refractory adhesive layer (20). In particular, yellow clay, which contains silica (SiO2), alumina (Al2O3), and iron oxide (Fe2O3) as main components, can effectively prevent the refractory adhesive layer (20) from being lost when ceramicized at high temperatures of 300°C or higher.

[0096] For example, refractory minerals in the form of hydrates, such as aluminum hydroxide, alumina trihydrate, and magnesium hydroxide, undergo endothermic reactions while releasing water of crystallization during thermal decomposition. For example, aluminum hydroxide begins thermal decomposition at about 180 to 200°C and exhibits a high heat absorption of about 1170 J / g, and aluminum oxide produced after decomposition has a high melting point of about 2000°C, which can provide additional heat resistance.

[0097] Additionally, the above-mentioned refractory inorganic materials also function as heat-dissipating fillers. In particular, oxides such as aluminum oxide, zinc oxide, and magnesium oxide possess appropriate thermal conductivity and effectively dissipate generated heat. This can contribute to preventing localized temperature increases and improving overall heat management efficiency.

[0098] These refractory minerals also exhibit a synergistic effect with other components of the refractory adhesive layer (20). The ceramicization of clay minerals stabilizes the expanded structure of expanded graphite, the endothermic reaction of hydrates promotes the formation of a carbonized layer of the phosphorus flame retardant, and the oxides strengthen the formed carbonized layer, thereby forming a more effective fire barrier.

[0099] The particle size of the refractory minerals is also an important consideration. Nano-sized particles can be uniformly dispersed within the acrylic copolymer matrix, providing a reinforcing effect and contributing to improved product durability and reliability. Surface treatment can further enhance dispersibility and compatibility, if necessary.

[0100] Through the complex action of these refractory inorganic substances, the refractory adhesive layer (20) of the present invention can simultaneously exhibit excellent refractory performance and heat dissipation performance, and in particular, it performs a continuous protective function without being lost even at high temperatures of 300°C or higher, and can greatly improve the fire safety of electric vehicle batteries.

[0101] The particle size of the yellow clay used in the refractory adhesive layer (20) of the present invention may preferably be 10 to 40 μm. For example, if the particle size of the yellow clay is less than 10 μm, the specific surface area may increase excessively, which may easily cause agglomeration within the acrylic copolymer matrix, making uniform dispersion difficult throughout the refractory adhesive layer (20). In addition, excessively small particles may restrict the chain movement of the acrylic copolymer, which may significantly reduce the adhesive strength, and it may be difficult to form a sufficient structure during the ceramicization process.

[0102] On the other hand, when the particle size of the yellow clay exceeds 40 μm, the smoothness of the refractory adhesive layer (20) may be reduced due to the large particles, which may lead to a decrease in the adhesive strength with the adherend. In addition, the gap between the large particles may increase, which may reduce the continuity of the inorganic structure formed after ceramicization, and this may cause a decrease in the structural stability of the refractory adhesive layer (20) in the event of a fire. In particular, excessively large yellow clay particles within the limited thickness of the refractory adhesive layer (20) may cause an uneven stress distribution within the layer, which may adversely affect long-term reliability.

[0103]

[0104] At this time, the thickness of the fire-resistant adhesive layer (20) of the present invention is preferably 40 to 1300 μm. Here, the thicker the fire-resistant adhesive layer (20), the better the fire-resistant performance can be, and the fire-resistant adhesive layer (20) of the present invention is characterized in that it can satisfy the fire-resistant performance exceeding the predetermined specifications even with a thin thickness.

[0105] For example, if the thickness of the refractory adhesive layer (20) is less than 40 μm, the adhesive layer is too thin to secure sufficient adhesive strength, and additives such as refractory inorganic substances and expanded graphite may not be uniformly dispersed. In addition, it may be difficult to secure sufficient expansion space for the expanded graphite in the event of a fire, and it may also be difficult to secure structural stability through ceramicization of the refractory inorganic substances.

[0106] On the other hand, if the thickness of the refractory adhesive layer (20) exceeds 1300 μm, the adhesive layer may be too thick, resulting in reduced flexibility and workability, and there is a risk of interlayer delamination due to increased internal stress. In addition, excessive thickness may increase drying time and increase manufacturing costs.

[0107] In addition, the fire-resistant adhesive layer (20) of the present invention may be composed of 40 to 70 parts by weight of a synthetic resin, 5 to 15 parts by weight of a phosphorus-based flame retardant, 5 to 20 parts by weight of a refractory inorganic material, 10 to 20 parts by weight of a thermal expansion material, and the remainder of additives, based on a total of 100 parts by weight. This composition ratio is designed so that the functions of each component can be optimally expressed.

[0108] For example, the synthetic resin mainly uses an acrylic copolymer, and accounts for 40 to 70 parts by weight of the total composition to provide basic adhesive characteristics and physical properties. The phosphorus-based flame retardant is blended in an amount of 5 to 15 parts by weight to exhibit effective flame retardant performance, and in particular, can perform a fire prevention function through the formation of a carbon layer. The refractory inorganic material is blended in an amount of 5 to 20 parts by weight to provide structural stability at high temperatures, and in particular, prevents the loss of the fire-resistant adhesive layer (20) through the ceramization of yellow clay. The thermal expandable material is blended in an amount of 10 to 20 parts by weight to provide a space blocking effect through expansion in the event of a fire. Through such an optimized blending ratio, the fire-resistant adhesive layer (20) can effectively exhibit various protective functions required in the event of a fire along with excellent adhesive characteristics. That is, while providing stable adhesive strength at room temperature, in the event of a fire, the expansion of the expanded graphite, the formation of the carbon layer of the phosphorus-based flame retardant, and the ceramization of yellow clay work in combination to exhibit excellent fire prevention performance.

[0109] In addition, the refractory adhesive layer (20) of the present invention may include various additives in addition to the main components as needed, as long as the purpose of the invention is not impaired. At this time, the type of the additive component is not particularly limited, and various additives may be used. For example, a dispersant that helps uniformly disperse the additives may be used, and in particular, a silane-based coupling agent or surfactant may be used to improve the dispersion stability of inorganic particles such as refractory inorganic materials or expanded graphite. In addition, an isocyanate-based or epoxy-based compound may be used as a curing agent to control the crosslinking degree of the synthetic resin, thereby improving the heat resistance and cohesiveness of the refractory adhesive layer (20). In addition, a curing accelerator or curing retardant may be added as needed to control the curing speed. Organic solvents such as toluene, ethyl acetate, and methyl ethyl ketone may be used as solvents required in the process of manufacturing the adhesive, and these serve to control the application properties and drying characteristics of the adhesive. In addition, workability and application uniformity can be optimized through a viscosity modifier. Stabilizers such as antioxidants and UV stabilizers can be used to improve the long-term reliability of the refractory adhesive layer (20), and colorants or pigments can be used to provide product identification, if necessary. Furthermore, antifoaming agents can effectively remove air bubbles that may occur during the manufacturing process. These additives can be added in appropriate amounts for each purpose to optimize the properties and performance of the refractory adhesive layer (20), and the amount of additives can be appropriately selected within a range that does not impair formability, etc. The additives can be used alone or in combination of two or more.

[0110]

[0111] In addition, the method for manufacturing the above-mentioned fire-resistant sheet for an electric vehicle battery can be manufactured through a step of preparing a flame-blocking layer, a step of preparing a fire-resistant adhesive layer, and a step of bonding the flame-blocking layer and the fire-resistant adhesive layer to each other, which will be described in detail below.

[0112]

[0113] Hereinafter, experimental examples, manufacturing examples, and / or examples of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the experimental examples, manufacturing examples, and / or examples described herein.

[0114]

[0115] < Manufacturing Example >

[0116] Manufacturing Example 1: Manufacturing of a fire-resistant adhesive layer (excluding phosphorus-based flame retardant)

[0117] After adding an isocyanate series hardener and MEK (Methyl Ethyl Ketone) to an acrylic copolymer PSA and stirring sufficiently, expanded graphite with a particle size of 40 to 50 μm as a thermal expansion agent was added and stirred, and then yellow clay was added and stirred to obtain a syrup with a solid content of 55%.

[0118] Additionally, after stirring for 5 minutes at a rotation speed of 1800 RPM using a stirrer, reverse stirring was performed to degas, and then roll coating was used to coat a polyester release film with a thickness of 250 μm.

[0119] Afterwards, the sample was dried for 3 minutes in a 125℃ convection oven to dry all residual solvent, and then cooled sufficiently to room temperature. When the thickness was measured, it was confirmed to be approximately 100 μm.

[0120] Afterwards, a refractory adhesive layer was manufactured by maturing for more than 48 hours in a maturing room with a temperature environment of 50℃ to ensure sufficient crosslinking reaction.

[0121] Examples 1 and 2 were manufactured using the above manufacturing example 1.

[0122]

[0123] Manufacturing Example 2: Manufacturing of a fire-resistant adhesive layer (including a phosphorus-based flame retardant)

[0124] It was manufactured in the same manner as Manufacturing Example 1, except that an additional flame retardant was added.

[0125] Examples 3 to 9 were manufactured using the above manufacturing example 2.

[0126]

[0127] Manufacturing Example 3: Manufacturing of refractory sheet

[0128] The refractory adhesive layers of Examples 1 to 9 were laminated with a mica sheet having a thickness of 150 μm to manufacture the refractory sheets of Examples 10 to 18. At this time, the lamination of the refractory adhesive layers and the mica sheet was performed through a laminating method.

[0129]

[0130] < Example >

[0131] The mixing ratios (based on 100 parts by weight of the total) of Examples 1 to 9 manufactured using Manufacturing Examples 1 and 2 are summarized in Table 1 below.

[0132]

[0133] Acrylic copolymer PSA Expanded graphite Yellow earth flame retardant Other additives Example 1608.315 - Residual amount Example 2608.320 - Residual amount Example 35510264 Residual amount Example 45510266.6 Residual amount Example 550102610 Residual amount Example 65015.9264 Residual amount Example 76014.89.113.4 Residual amount Example 86015.39.111.8 Residual amount Example 96016.99.111.8 Residual amount

[0134]

[0135] <Experimental Example>

[0136] Experimental Example 1-1: Adhesion Test

[0137] In order to measure the adhesive strength of the refractory adhesive layer (20) to the SUS304 plate, the adhesive strength was tested based on ASTM D3330, a standard test method for measuring the adhesive strength (peel adhesion) of adhesive tape. At this time, the leaving time was 30 minutes at room temperature (23℃ / 50% environment).

[0138]

[0139] Experimental Example 1-2: Flame Retardancy Test

[0140] For the manufactured refractory adhesive layer (20), a combustion test was conducted based on the UL94V standard, a safety standard for evaluating the combustibility of plastic materials, and the flame retardancy was determined.

[0141] Here, the UL94V flame retardancy test determines the grade by measuring three main items: first, the total time taken for primary and secondary combustion and extinguishment of sparks for each individual specimen is measured, next, the sum of the primary and secondary combustion times of five specimens is checked, and lastly, whether the cotton ignites due to the falling flame generated during the combustion process.

[0142] At this time, the test is conducted using a standardized specimen with a width of 0.5 inches (approximately 13 mm) and a length of 5 inches (approximately 127 mm), and the test method is to adjust the height of a blue flame generated by methane gas to 3 / 4 inch (approximately 19 mm), and then contact this single flame with the specimen for 10 seconds, and when the flame is removed and the combustion of the specimen naturally stops, the process of contacting the flame again for 10 seconds in the same manner is repeated, and based on the test results, the flame retardancy grade is determined according to the predetermined criteria in Table 2 below.

[0143]

[0144] Sum of the 1st and 2nd combustion times and the spark extinguishing time of each specimen Total sum of the 1st and 2nd combustion times of 5 specimens Ignition of cotton due to falling sparks V-0 Within 10 seconds Within 50 seconds Should not be present V-1 Within 30 seconds Within 250 seconds Should not be present V-2 Within 30 seconds Within 250 seconds May be present

[0145]

[0146] The experimental results for Experimental Examples 1-1 and 1-2 are summarized in Table 3 below.

[0147]

[0148] Adhesion gf / 25mm Flame retardancy Example 1656V-0 Example 2640V-0 Example 3501V-0 Example 4421V-0 Example 5201V-0 Example 6122V-0 Example 7497V-0 Example 8424V-0 Example 9427V-0

[0149]

[0150] In the flame retardancy test, all examples 1 to 9 were confirmed to have flame retardancy performance of V-0 or higher. However, in the adhesion test, it was confirmed that the adhesion was measured differently depending on the example.

[0151] Specifically, excellent adhesion was measured in Examples 1 and 2, in which no phosphorus flame retardant was added, and it was confirmed that Example 2, in which more yellow clay was added, had slightly lower adhesion than Example 1. Through this, it was confirmed that the adhesion performance decreased as the weight portion of the refractory inorganic material increased.

[0152] Meanwhile, although Examples 1 to 9 all had excellent flame retardant performance, it was confirmed that the adhesive strength was low in some examples, making them difficult to use as actual products. Specifically, when comparing Examples 3 and 4, it was confirmed that the adhesive strength slightly decreased as more phosphorus-based flame retardants were included, and when looking at the results of Experimental Examples 5 and 6, it was confirmed that the adhesive strength decreased significantly when the expanded graphite, yellow clay, and phosphorus-based flame retardant exceeded 45 parts by weight out of the total 100 parts by weight.

[0153] In addition, in light of the results of Experimental Examples 7 to 9, it was confirmed that the adhesive strength slightly decreased as the weight ratio of expanded graphite increased.

[0154] Therefore, in order to achieve a certain level of adhesiveness, the weight of the refractory inorganic material (yellow clay) should be maintained at 5 to 20 parts by weight, and the expanded graphite, yellow clay, and phosphorus flame retardant should be managed so that they do not exceed 45 parts by weight out of the total 100 parts by weight.

[0155]

[0156] Experimental Example 2: Fire Resistance Test

[0157] A fire resistance test was performed on the refractory sheets of Examples 10 to 18. In this case, Example 10 was a refractory sheet having a thickness of 250 μm manufactured by laminating a mica sheet to Example 1, and similarly, Examples 11 to 18 were refractory sheets having a thickness of 250 μm manufactured by laminating a mica sheet to Examples 2 to 9.

[0158] In addition, Comparative Example 1 was manufactured by laminating a mica sheet to the adhesive layer (general) of Company 1, and Comparative Example 2 was manufactured by laminating a mica sheet to the adhesive layer (flame retardant) of Company 2.

[0159]

[0160] The fire resistance test method is as follows.

[0161]

[0162] 1) The specimen shall have an area of ​​75mm*75mm and be attached to a 0.7mm thick SUS304 steel plate.

[0163] 2) To determine the fire resistance performance, set each horizontally aligned torch to maintain a distance of 150 mm between the discharge port and the specimen, and adjust the torch intensity to set the applied temperature to 1300℃.

[0164] 3) The prepared sample was set up, the torch flame was directed toward the flame blocking layer, and the temperature was measured by attaching a thermometer to the SUS304 steel plate on the opposite side of the flame irradiation at intervals of 5, 10, 20, and 30 minutes based on the start time of flame application.

[0165]

[0166] The experimental results for Experimental Example 2 are summarized in Table 4 below.

[0167]

[0168] Fire resistance, heat insulation (℃) 5 minutes 10 minutes 20 minutes 30 minutes SUS304 single 51 15 20 5 18 5 23 Example 10 35 6 39 5 4 2 2 4 21 Example 11 35 23 8 8 4 1 0 4 10 Example 12 32 23 4 6 36 6 38 9 Example 13 31 0 3 4 0 3 5 0 3 7 0 Example 14 32 7 34 5 35 7 36 8 Example 15 36 0 3 6 2 3 5 9 35 3 Example 16 31 43 5 4 3 6 1 3 6 8 Example 17 28 43 4 5 34 9 35 2 Example 18 28 7 34 2 3 5 4 3 5 6

[0169]

[0170] As a result of the experiment, looking at Examples 10 and 11, it was confirmed that the temperature difference of the refractory sheet laminated with the refractory adhesive layer (20) without the phosphorus flame retardant added was slightly reduced compared to SUS304 alone (reference point), and as a result, it was confirmed that the refractory adhesive layer (20) without the phosphorus flame retardant added had poor fire resistance.

[0171] In addition, it was confirmed that the greater the combined weight of the three materials (expanded graphite, yellow clay, and phosphorus-based flame retardant), the better the fire resistance and heat insulation properties. However, when the combined weight of the three materials (expanded graphite, yellow clay, and phosphorus-based flame retardant) exceeded 45, it was confirmed that the fire resistance and heat insulation properties were somewhat reduced. As seen in Experimental Example 1-1 above, when the combined weight of the three materials (expanded graphite, yellow clay, and phosphorus-based flame retardant) exceeded 45, the adhesiveness was significantly reduced, and it may be difficult to perform the proper function by being detached from the adherend.

[0172] In addition, when comparing Example 16 and Example 18, it was confirmed that the higher the content of the phosphorus flame retardant, the better the fire resistance is not necessarily, but that the fire resistance can be improved only when the appropriate ratio with the expanded graphite is adjusted.

[0173]

[0174] Table 5 and Drawing 2 below are tables showing the experimental results for Comparative Example 1, Comparative Example 2, and Experimental Example 2 of Example 17. In this case, Comparative Example 1 was manufactured by laminating a mica sheet to the adhesive layer (general) of Company 1, and Comparative Example 2 was manufactured by laminating a mica sheet to the adhesive layer (flame retardant) of Company 2.

[0175]

[0176] Fire resistance, heat insulation (℃), adhesive layer loss, 5 minutes, 10 minutes, 20 minutes, 30 minutes, SUS304, single, 511520518523 - Comparative example, 1435422434444, loss, comparative example, 2320362371374, loss, practical example, 17284345349352, no loss

[0177]

[0178] Referring to Table 5 and FIG. 4, it was confirmed with the naked eye that the fire-resistant sheets of Comparative Examples 1 and 2 lost their adhesive layers, whereas the fire-resistant sheet of Example 17 of the present invention did not lose its adhesive layer. In addition, Comparative Example 1, which used a general adhesive layer, did not show a significant difference in fire resistance from SUS304 alone (reference point), and Comparative Example 2, which used a fire-resistant adhesive layer, measured comparable fire resistance to SUS304 alone (reference point) and Comparative Example 1, but it was confirmed that the adhesive layer was lost.

[0179]

[0180] Above, the present invention has been described in detail with reference to the drawings and preferred embodiments, but the scope of the technical idea of ​​the present invention is not limited to these drawings and embodiments.

[0181] In addition, in order to more clearly express the technical idea of ​​the present invention, the attached drawings briefly express or omit components that are not related to or have little to do with the technical idea of ​​the present invention.

[0182] That is, it is obvious to those skilled in the art that the present invention can be variously changed or modified within the spirit and scope of the present invention, and therefore, it is made clear that such changes or modifications fall within the scope of the appended patent claims.

[0183] Furthermore, various modifications or equivalent embodiments may exist within the scope of the technical concept of the present invention. Therefore, the scope of the technical concept according to the present invention should be interpreted by the claims, and technical concepts equivalent to or within the scope of the claims should be interpreted as falling within the scope of the present invention.

[0184]

[0185] The fire-resistant sheet for an electric vehicle battery according to the present invention can simultaneously achieve excellent flame blocking performance and fire resistance despite its thin thickness.

[0186] In addition, it provides excellent initial adhesion while maintaining a thin thickness, enabling stable attachment. Due to these characteristics, it can be widely applied to various parts of an electric vehicle battery system, such as the contact pressure pad between battery cells, battery module cover, and battery pack cover.

[0187] Additionally, the tape does not burn out even when exposed to high temperatures, providing a continuous fire prevention effect, which means that it can perform a stable fire spread prevention function even in a thermal runaway situation of the battery.

[0188] Additionally, the manufacturing process can be simplified compared to existing refractory materials, which can improve productivity and reduce costs.

Claims

1. A flame barrier layer that blocks direct heat transfer from the flame; and A fire-resistant adhesive layer laminated on the above flame-blocking layer; The above refractory adhesive layer is, A refractory sheet for an electric vehicle battery, characterized by comprising a synthetic resin, a thermal expansion agent, a phosphorus flame retardant, and a refractory inorganic material.

2. In paragraph 1, The above flame blocking layer is, A fire-resistant sheet for an electric vehicle battery, characterized by being any one selected from among mica sheets, metal sheets, silica sheets, alumina sheets, glass fibers, flame-retardant nonwoven fabrics, fire-resistant fibers, carbon fibers, and combinations thereof.

3. In paragraph 1, The above refractory minerals are, A fire-resistant sheet for an electric vehicle battery, characterized by being at least one selected from among yellow soil, bentonite, kaolin, aluminum hydroxide, aluminum oxide, alumina trihydrate (ATH), magnesium hydroxide, zinc oxide, magnesium oxide, and combinations thereof.

4. In paragraph 1, The above synthetic resin, A fire-resistant sheet for an electric vehicle battery, characterized by being made of any one selected from acrylic resin, epoxy resin, polyvinyl acetal resin, polyvinyl chloride resin, polyolefin resin, and combinations thereof.

5. In paragraph 4, The above acrylic resin, A fire-resistant sheet for an electric vehicle battery, characterized by being any one selected from polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polybutylacrylate (PBA), polymethyl acrylate (PMA), acrylic copolymer, and combinations thereof.

6. In paragraph 1, The above thermal expansion material is, A refractory sheet for an electric vehicle battery characterized by being any one selected from expandable graphite, vermiculite, perlite, expandable mica, and combinations thereof.

7. In paragraph 1, The content ratio of the above refractory adhesive layer is: A fire-resistant sheet for an electric vehicle battery, characterized in that it comprises 40 to 70 parts by weight of the synthetic resin, 5 to 15 parts by weight of the phosphorus flame retardant, 5 to 20 parts by weight of the refractory inorganic material, 10 to 20 parts by weight of the thermal expansion material, and the remainder of additives, for a total of 100 parts by weight of the fire-resistant adhesive layer.

8. In paragraph 7, The above refractory adhesive layer is, A fire-resistant sheet for an electric vehicle battery, characterized in that the combined weight of the phosphorus flame retardant, the refractory inorganic material, and the thermal expansion agent is 45 weight parts or less out of the total 100 weight parts of the fire-resistant adhesive layer.

9. In paragraph 1, A fire-resistant sheet for an electric vehicle battery, characterized in that the thickness of the flame-blocking layer is 50 to 1000 μm, and the thickness of the fire-resistant adhesive layer is 40 to 1300 μm.

10. In paragraph 1, The above refractory adhesive layer is, A fire-resistant sheet for electric vehicle batteries, characterized by having an adhesive strength of 400 gf / 25 mm or more as measured according to ASTM D3330 while satisfying the UL94 V-0 flame retardancy rating.

11. In paragraph 1, The above fire-resistant sheet for an electric vehicle battery is characterized in that it is attached to any one part selected from the group consisting of a pressure pad between battery cells, a module cover covering the outside of a battery module, an inner surface of a battery pack in which a battery module is stored, a battery pack cover covering the outside of a battery pack, a gap between battery modules, a cover for protecting electrical wiring inside a battery pack, and a combination thereof.

12. A method for manufacturing a refractory sheet for an electric vehicle battery, A step in which a flame barrier layer is prepared to block direct heat transfer from the flame; A step of preparing a fire-resistant adhesive layer laminated on the above flame-blocking layer; and A step in which the above flame blocking layer and the above fire-resistant adhesive layer are combined with each other; The above refractory adhesive layer is, A method for manufacturing a refractory sheet for an electric vehicle battery, characterized in that it comprises a synthetic resin, a thermal expansion agent, a phosphorus flame retardant, and a refractory inorganic material.

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