Highly adhesive and 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, acrylic monomer, thermal expansion material, inorganic flame retardant, and an additive.

Description

High-adhesion fire-resistant sheet for electric vehicle batteries with excellent flame blocking and fire resistance performance and 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 high-adhesion refractory sheet for electric vehicle batteries, 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 high-adhesion refractory material for electric vehicle batteries 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 includes a flame-blocking layer that blocks direct heat transfer from a flame and a fire-resistant adhesive layer laminated on the flame-blocking layer, and the fire-resistant adhesive layer is characterized in that it includes a synthetic resin, an acrylic monomer, a heat-expanding material, an inorganic flame retardant, and an additive.

[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 content ratio of the fire-resistant adhesive layer is characterized in that it includes 15 to 30 parts by weight of synthetic resin, 5 to 15 parts by weight of acrylic monomer, 40 to 70 parts by weight of inorganic flame retardant, 3 to 15 parts by weight of thermal expansion agent, and the remainder of additives, based on 100 parts by weight of the total fire-resistant adhesive layer.

[0017] In addition, the thermal expansion material is characterized by being one selected from expandable graphite, vermiculite, perlite, expandable mica, and a combination thereof.

[0018] 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.

[0019] In addition, the acrylic monomer is characterized in that it is any one selected from 2-Hydroxypropyl acrylate, 2-Hydroxyethyl acrylate, 4-Hydroxybutyl acrylate, isobornyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, t-butyl acrylate, glycidyl acrylate, dimethylaminoethyl acrylate, acryloylmorpholine, and combinations thereof.

[0020] In addition, the thickness of the flame blocking layer is 50 to 1000 μm, and the thickness of the fire-resistant adhesive layer is 100 to 3000 μm.

[0021] In addition, the above-mentioned fire-resistant adhesive layer is characterized by having an adhesive strength of 800 gf / 25 mm or more measured based on ASTM D3330 while satisfying the UL94 V-0 flame retardancy rating.

[0022] In addition, the refractory adhesive layer further includes a refractory inorganic substance, and the refractory inorganic substance 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.

[0023] In addition, the content ratio of the refractory adhesive layer is characterized in that it further includes 5 to 20 parts by weight of refractory inorganic material based on 100 parts by weight of the total refractory adhesive layer.

[0024] 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.

[0025]

[0026] 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, an acrylic monomer, a heat-expanding material, an inorganic flame retardant, and an additive.

[0027]

[0028] The fire-resistant sheet for an electric vehicle battery according to the present invention can simultaneously achieve excellent flame blocking performance and fire resistance.

[0029] In addition, the refractory adhesive layer provides excellent expansion thickness and adhesive strength, 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.

[0030] In addition, the excellent stress dissipation ability due to the foam structure of the refractory adhesive layer effectively absorbs shock and vibration, and acts as an insulating layer that delays heat transfer, so it can act as a more effective protective film when exposed to direct flame or high temperatures.

[0031] 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.

[0032] Additionally, the manufacturing process can be simplified compared to existing refractory materials, which can improve productivity and reduce costs.

[0033] 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.

[0034]

[0035] FIGS. 1 to 3 are drawings for explaining a refractory sheet for an electric vehicle battery according to one embodiment of the present invention.

[0036] 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.

[0037]

[0038] 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.

[0039] 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.

[0040]

[0041] FIGS. 1 to 3 are drawings for explaining a refractory sheet for an electric vehicle battery according to one embodiment of the present invention.

[0042]

[0043] Referring to FIGS. 1 to 3, a fire-resistant sheet for an electric vehicle battery according to an embodiment of the present invention includes a flame-blocking layer (10) and a fire-resistant adhesive layer (20). In this case, 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, satisfies the V-0 grade of the UL94 test, and has excellent adhesive strength. In addition, since the fire-resistant adhesive layer (20) is formed of a foam structure (foam structure) containing bubbles in the adhesive structure, the fire-resistant adhesive layer (20) can serve as an insulating layer that delays heat transfer, which can improve heat blocking performance in the event of a fire. In particular, since the bubbles inside the foam structure have the effect of dispersing heat and delaying heat transfer, it can serve as a more effective protective film when exposed to direct flame or high temperature. Additionally, the foam structure is thicker than the PSA (Pressure Sensitive Adhesives) structure, and this thick structure allows for the inclusion of more refractory additives such as flame retardants or heat-conducting fillers, which can improve the overall refractory performance.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 as the outermost layer, 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 as the outermost layer, 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.

[0048]

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] For example, the manufacturing of mica sheets can be comprised of the steps of exfoliation, shaping, and post-processing of mica.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 the mica sheet. 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.

[0063] For example, the metal sheet may include stainless steel (SUS), Invar, and a super heat-resistant alloy.

[0064] 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.

[0065] 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 fire, resulting in excellent dimensional stability, which can be a key factor in enhancing the reliability of fire-resistant performance.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070]

[0071] 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 and providing an insulating effect due to its foam structure (foam structure). At this time, the essential characteristics of the fire-resistant adhesive layer (20) include that it should not be lost even at a predetermined temperature and maintain its shape to provide a continuous insulating effect, while maintaining adhesive strength. This may be to prevent the fire-resistant sheet for an electric vehicle battery from losing adhesive strength due to flame and being detached from the attachment.

[0072] For example, the fire-resistant adhesive layer (20) may include synthetic resin, acrylic monomer, thermal expansion material, inorganic flame retardant, etc. 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 may preferably be acrylic resin, but is not limited thereto, and may be modified in various ways at a level obvious to a person skilled in the art.

[0073] Here, the acrylic resin used in the refractory adhesive layer (20) of the present invention provides excellent adhesive properties and durability, and is a component that forms a base of a foam structure. The acrylic resin can play a role in forming and maintaining an appropriate bubble structure during the foaming process. For example, the acrylic resin may be any one selected from polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polybutyl acrylate (PBA), polymethyl acrylate (PMA), an acrylic copolymer, and a combination thereof. Preferably, an acrylic copolymer may be adopted, but the present invention is not limited thereto, and various modifications may be made at a level obvious to those skilled in the art.

[0074] For example, PMMA has a high glass transition temperature (approximately 105°C) and excellent mechanical strength, which can improve the structural stability of foams. In particular, the methyl side chains of PMMA enable uniform distribution of bubbles during the foaming process, which can contribute to the uniformity of physical properties of the final product. In addition, PMMA can provide additional flame retardancy by forming a carbon layer (cha) during pyrolysis. PBA can provide excellent flexibility and adhesion properties at room temperature due to its low glass transition temperature (approximately -54°C), and the appropriate length of the butyl side chain in PBA enables good wetting with the adherend, which can realize high adhesion. PEA has an intermediate glass transition temperature (approximately -24°C), which can be effective in balancing adhesion and cohesion, and in the case of PMA, an oxygen barrier effect can also be expected due to the dense structure of the methyl side chain.

[0075] In particular, for acrylic copolymers, foaming characteristics and physical properties can be optimized through the combination of different monomers. For example, a copolymer of PMMA and PBA can simultaneously achieve the structural stability of PMMA and the flexibility of PBA, and the physical properties of the final product can be precisely controlled by adjusting the copolymerization ratio. Furthermore, a copolymer of PEA and PMA can provide enhanced heat resistance along with appropriate adhesive strength.

[0076] Additionally, the molecular weight and molecular weight distribution of the acrylic resin significantly affect the foam properties. For example, a molecular weight in the range of 50,000 to 500,000 g / mol is applied, which can facilitate foam formation and stabilization during the foaming process. A broad molecular weight distribution (PDI > 2.0) can contribute to improved processability, which can help form a uniform foam structure. A foam-type fire-resistant adhesive (20) based on such an acrylic resin can simultaneously realize excellent adhesive properties and fire resistance, and an insulating effect due to the foam structure can also be expected, thereby significantly contributing to the improvement of the safety of electric vehicle batteries.

[0077]

[0078] In addition, the acrylic monomer, which is one of the main components of the refractory adhesive layer (20) of the present invention, may be a component for forming a foam structure. For example, the acrylic monomer may be any one selected from 2-Hydroxypropyl acrylate, 2-Hydroxyethyl acrylate, 4-Hydroxybutyl acrylate, isobornyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, t-butyl acrylate, glycidyl acrylate, dimethylaminoethyl acrylate, acryloylmorpholine, and combinations thereof. It is possible to adopt, preferably, 2-Hydroxypropyl acrylate and isobornyl acrylate, but is not limited thereto, and can be modified in various ways at a level obvious to those skilled in the art.

[0079] Here, acrylic monomers containing a hydroxyl group (-OH) can form hydrogen bonds or chemical bonds with other components in the fire-resistant adhesive layer (20) due to the hydroxyl group in the molecule, thereby improving both fire resistance and adhesive strength, and acrylic monomers containing a cyclic structure have excellent thermal stability due to the ring structure in the molecule, and in particular, isobornyl acrylate can improve heat resistance by providing a high glass transition temperature (Tg) due to its rigid bicyclic structure, and acrylic monomers containing an alkyl group can control adhesive properties through an appropriate side chain structure, and in the case of 2-ethylhexyl acrylate, excellent adhesive strength can be provided due to its long alkyl chain, and among functional acrylic monomers, glycidyl acrylate can undergo a crosslinking reaction through an epoxy group, and dimethylaminoethyl acrylate and acryloylmorpholine can improve adhesive strength and compatibility through their polar groups. In particular, these monomers form an appropriate cross-linking structure with synthetic resins (e.g., acrylic resins) during the foaming process, enabling uniform bubble distribution. Furthermore, they interact with thermal expansion agents, inorganic flame retardants, and other materials to simultaneously achieve excellent fire resistance and adhesive properties. This could play a significant role in improving the fire safety of electric vehicle batteries.

[0080]

[0081] In addition, the thermal expandable material, which is one of the main components of the refractory adhesive layer (20) of the present invention, can serve as a nucleating agent for forming bubbles during the foaming process. For example, the thermal expandable material may be any one selected from expandable graphite, vermiculite, perlite, expandable mica, and a combination thereof, preferably expandable graphite, but is not limited thereto and can be modified in various ways as would be apparent to a person skilled in the art.

[0082] 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.

[0083] 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.

[0084] 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 may be reduced, and if the particle size 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 entire 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 blocking layer (10), and excellent fire prevention performance can be realized through a synergistic effect with other flame retardant components.

[0085] In addition, thermal expansion agents have a complementary effect with other additives such as inorganic flame retardants. The moisture released when hydrate-based flame retardants such as aluminum hydroxide or magnesium hydroxide are thermally decomposed can promote the expansion of the thermal expansion agent, and at the same time, the porous structure formed by the thermal expansion agent can effectively capture the decomposition gases of these hydrates to maximize the cooling effect.

[0086] 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.

[0087] For example, when a fire occurs, expanded graphite can rapidly expand due to the gas generated when an intercalating agent, 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 worm-shaped porous structure formed can form a physical barrier within the fire-resistant adhesive layer (20), blocking the inflow of oxygen and hindering heat transfer. In addition, as the expanded graphite expands, the volume of the fire-resistant adhesive layer (20) increases, which effectively seals the area where a fire occurred and can be particularly effective in preventing the spread of fire through gaps or gaps in an electric vehicle battery system. Furthermore, the porous structure of the expanded graphite can provide excellent insulation performance because it contains many air layers inside, and this insulation effect can contribute to inhibiting the spread of fire by delaying heat transfer. Due to the action of the expanded graphite, the fire-resistant adhesive layer (20) of the present invention can exhibit active fire prevention performance beyond a simple adhesive function, which can significantly improve the safety of electric vehicle batteries.

[0088] 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 adhesive strength with the adherend.

[0089]

[0090] In addition, the inorganic flame retardant used in the fire-resistant adhesive layer (20) of the present invention is a main component that improves the fire resistance performance of the fire-resistant adhesive layer (20), and the inorganic flame retardant may be any one selected from among aluminum hydroxide, aluminum oxide, alumina trihydrate (ATH), magnesium hydroxide, zinc oxide, magnesium oxide, and combinations thereof, and preferably, aluminum hydroxide and aluminum oxide may be adopted, but the present invention is not limited thereto and may be modified in various ways at a level apparent to a person skilled in the art.

[0091] Here, inorganic flame retardants have a relatively small effect on UV transmittance, so they can provide effective flame retardant performance without interfering with the photopolymerization reaction of acrylic monomers. In particular, hydrate-based flame retardants such as aluminum hydroxide, alumina trihydrate, and magnesium hydroxide offer multiple flame retardant mechanisms, which can undergo endothermic reactions while releasing water of crystallization upon thermal decomposition. For example, alumina trihydrate begins to decompose at approximately 180 to 200°C and exhibits a high heat absorption of approximately 1170 J / g. The released moisture effectively diffuses through the pore structure of the foam, maximizing the cooling effect. Furthermore, oxide-based flame retardants such as aluminum oxide, zinc oxide, and magnesium oxide inherently possess high heat resistance and can act as fillers to reinforce the cell walls of the foam formed during the UV curing process. In particular, aluminum oxide has a high melting point of approximately 2000°C, enabling it to provide stable protection even in extreme fire conditions.

[0092] The particle characteristics of inorganic flame retardants significantly impact the performance of UV-curable foams. Particles with an appropriate particle size distribution can promote uniform foam formation and enhance foam stability during UV curing. Furthermore, nano-sized particles can effectively reinforce the foam walls within the foam's foam structure, and their large surface area provides a more effective cooling effect during thermal decomposition.

[0093] In particular, inorganic flame retardants exhibit excellent compatibility with acrylic monomers and photoinitiators, enabling them to form a stable dispersion in UV-curable systems. This is a crucial factor in ensuring uniformity of the curing reaction and improving the physical properties of the final product. Furthermore, they can work complementarily with other additives, such as thermal expansion agents and refractory inorganic materials, to maximize the fire resistance of foams.

[0094] Through these complex actions, the refractory adhesive layer (20) of the present invention can exhibit excellent refractory performance even in the UV curing process, which can contribute to significantly improving the safety of electric vehicle batteries.

[0095]

[0096] In addition, the fire-resistant adhesive layer (20) of the present invention may include additives such as a photoinitiator and a coagulant. For example, the photoinitiator plays a role in initiating photopolymerization of an acrylic monomer by generating radicals through UV irradiation, which may contribute to stabilizing the bubble structure formed through a mechanical foaming process. Here, the photoinitiator may be classified into a Type I photoinitiator, which is an α-cleavage type that decomposes alone to generate radicals, and a Type II photoinitiator, which is a hydrogen abstraction type that generates radicals through a reaction with a hydrogen donor, depending on the radical generation mechanism. For example, the photoinitiator may be 1-hydroxy cyclohexyl phenyl ketone, benzophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,2-dimethoxy-2-phenylacetophenone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, benzophenone, It may be any one selected from thioxanthone, 4-(dimethylamino)benzophenone, isopropylthioxanthone, and combinations thereof, preferably 1-hydroxy cyclohexyl phenyl ketone, but is not limited thereto and may be modified in various ways as is apparent to those skilled in the art.For example, in the present invention, Type I and Type II photoinitiators may be appropriately combined and used as photoinitiators, and for example, 1-hydroxy cyclohexyl phenyl ketone and benzophenone may be used together to simultaneously optimize surface curing and internal curing. In addition, the content of the photoinitiator may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total refractory adhesive layer (20), which may be an optimal range that can secure a sufficient degree of curing while preventing discoloration or deterioration of physical properties due to the remaining photoinitiator.

[0097] For example, the coagulant may play a role in improving the internal strength of the UV-curable foam and stabilizing the cell structure, and for example, the coagulant may be any one selected from 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and combinations thereof, and preferably, 1,6-hexanediol diacrylate is used, and 1,6-hexanediol diacrylate is a flexible alkylene It has acrylate groups at the chain and both ends, so that it provides an appropriate crosslinking density during the photopolymerization process while maintaining the flexibility of the foam, and has excellent compatibility with inorganic flame retardants or other additives, so that a uniform foam structure can be formed. However, the present invention is not limited thereto, and various modifications can be made at a level obvious to those skilled in the art. In addition, the coagulant may be included in an amount of 0.01 to 1 part by weight based on the total 100 parts by weight of the fire-resistant adhesive layer (20). If it is less than 0.01 part by weight, it is difficult to secure sufficient mechanical strength, and if it exceeds 1 part by weight, the foam may become too rigid, which may deteriorate the adhesive properties.

[0098]

[0099] The thickness of the fire-resistant adhesive layer (20) of the present invention may be 100 to 3000 μm. In this case, when the thickness of the fire-resistant adhesive layer (20) is less than 100 μm, sufficient space for forming a UV-curable foam structure is not secured, making it difficult to obtain a uniform bubble distribution, and the bubble size may also be limited, making it difficult to form an effective insulating structure. In addition, due to a thickness that is too thin, the dispersion of the refractory inorganic material and the inorganic flame retardant may become uneven, which may result in partial uneven curing during UV curing. In particular, since sufficient space required for the behavior of the thermal expansion material is not secured, it may be difficult to exhibit the required expansion performance in the event of a fire. On the other hand, when the thickness of the fire-resistant adhesive layer (20) exceeds 3000 μm, UV light may not sufficiently reach the interior of the foam, causing uneven curing, which may result in the occurrence of an uncured region. Furthermore, excessive thickness can easily cause bubble coalescence or collapse during the foaming process, resulting in an uneven foam structure. In particular, thick foam structures pose a risk of delamination or cracking due to uneven distribution of internal stress, which can negatively impact long-term reliability. Furthermore, if the foam structure becomes too thick, mechanical properties deteriorate and flexibility decreases, making it difficult to adapt to the diverse geometries of electric vehicle battery systems.

[0100] In addition, the fire-resistant adhesive layer (20) of the present invention may be composed of 15 to 30 parts by weight of a synthetic resin, 5 to 15 parts by weight of an acrylic monomer, 40 to 70 parts by weight of an inorganic flame retardant, 3 to 15 parts by weight of a thermal expansion agent, and the remainder of additives, based on a total of 100 parts by weight. This composition ratio may be designed so that the functions of each component can be optimally expressed.

[0101] For example, the content of the synthetic resin is limited to 15 to 30 parts by weight because it is the optimal range required to form the basic matrix of the foam. If it is less than 15 parts by weight, it is difficult to form a stable foam structure. If it exceeds 30 parts by weight, the content of other functional additives is limited, which may result in a decrease in fire resistance performance. In addition, the content of the acrylic monomer is limited to 5 to 15 parts by weight because it is the range for forming an appropriate crosslinking structure through UV curing. If it is less than 5 parts by weight, it is difficult to obtain a sufficient degree of crosslinking, which may result in a decrease in the mechanical strength of the foam. If it exceeds 15 parts by weight, the foam may become too rigid due to excessive crosslinking. In addition, the content of the inorganic flame retardant is set to 40 to 70 parts by weight because it is necessary to secure sufficient fire resistance performance. If it is less than 40 parts by weight, it is difficult to achieve the required flame retardancy performance. If it exceeds 70 parts by weight, the UV curing reaction may be inhibited and the mechanical properties of the foam may be weakened. Furthermore, the content of thermal expansion agent is limited to 3 to 15 parts by weight to ensure adequate expansion performance in case of fire. Below 3 parts by weight, sufficient expansion effect is difficult to achieve, and above 15 parts by weight, the basic properties of the foam deteriorate and UV curing may be hindered. The content ratios of these components are closely related to each other, enabling optimal foam structure formation and fire resistance.

[0102]

[0103] In addition, the refractory adhesive layer (20) of the present invention may further include a refractory inorganic substance to further improve refractory performance and prevent loss of the refractory adhesive layer (20), and the refractory inorganic substance may be any one selected from yellow soil, bentonite, kaolin, aluminum hydroxide, aluminum oxide, alumina trihydrate (ATH), magnesium hydroxide, zinc oxide, magnesium oxide, and combinations thereof. At this time, yellow clay can be preferably used, wherein yellow clay is a natural clay mineral whose main components are silica (SiO2), alumina (Al2O3), iron oxide (Fe2O3), etc., and acts as a reinforcing agent to stabilize the bubble structure of the foam during the UV curing process, and can prevent the foam from being lost in the event of a fire through its characteristic of being ceramicized at a high temperature of 300℃ or higher. Here, the particle size of the yellow clay can be 10 to 40μm, which can be an optimal range for forming a uniform bubble structure and securing light transmittance during UV curing. The content of the refractory inorganic material can be further included in an amount of 5 to 20 parts by weight based on the total 100 parts by weight of the refractory adhesive layer (20). If it is less than 5 parts by weight, it is difficult to expect sufficient fire resistance performance, and if it exceeds 20 parts by weight, the UV curing reaction may be inhibited and the adhesive properties of the foam may deteriorate.

[0104]

[0105] In addition, the refractory adhesive layer (20) of the present invention may contain various additives as needed, in addition to the additives mentioned above, 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 for controlling the curing speed may be added as needed. 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 viscosity modifiers. Stabilizers such as antioxidants and UV stabilizers can be used to improve the long-term reliability of the refractory adhesive layer (20), and product identification can be provided through colorants or pigments as needed. In addition, air bubbles that may occur during the manufacturing process can be effectively removed through anti-foaming agents. These additives can be added in appropriate amounts for each purpose to contribute to optimizing 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.

[0106]

[0107] 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.

[0108]

[0109] 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.

[0110]

[0111] < Manufacturing Example >

[0112] Manufacturing Example 1: Manufacturing of a refractory adhesive layer

[0113] First, 22 parts by weight of acrylic copolymer, a synthetic resin, is mixed with MEK (Methyl Ethyl Ketone) and stirred thoroughly to produce a homogeneous solution. Next, 25 parts by weight of aluminum hydroxide and 33 parts by weight of aluminum oxide, inorganic flame retardants, are sequentially added while stirring.

[0114] Next, 8.76 parts by weight of 2-hydroxypropyl acrylate, an acrylic monomer, and 3 parts by weight of isobornyl acrylate are added, and then 8 parts by weight of expanded graphite with a particle size of 30 to 270 μm as a thermal expansion agent is added and stirred sufficiently.

[0115] Finally, 0.2 parts by weight of 1-hydroxycyclohexyl phenyl ketone as a photoinitiator and 0.04 parts by weight of 1,6-hexanediol diacrylate as a coagulant are added and stirred to obtain a uniform mixture.

[0116] Afterwards, the mixture is stirred for 5 minutes at 1800 RPM using a stirrer, followed by reverse stirring to undergo a defoaming process. Next, the mixture is coated to the target thickness on a release film using roll coating, and a foam structure is formed through a mechanical foaming process.

[0117] The foamed coating layer is irradiated with UV light to initiate a photopolymerization reaction. UV irradiation conditions should be set to an appropriate light intensity and time to ensure complete curing. After UV curing is complete, allow the coating to cool sufficiently to room temperature and then measure its thickness to confirm that the target thickness has been achieved.

[0118] Through this manufacturing process, Example 1 with a thickness of 300 μm, Example 2 with a thickness of 500 μm, and Example 3 with a thickness of 1300 μm were manufactured.

[0119]

[0120] Manufacturing Example 2: Manufacturing of refractory sheet

[0121] The refractory adhesive layers of Examples 1 to 3 were laminated with a mica sheet having a thickness of 150 μm to manufacture the refractory sheets of Examples 4 to 6. At this time, the lamination of the refractory adhesive layers and the mica sheet was performed through a laminating method.

[0122]

[0123] <Experimental Example>

[0124] Experimental Example 1-1: Adhesion Test

[0125] 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).

[0126]

[0127] Experimental Example 1-2: Flame Retardancy Test

[0128] 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.

[0129] 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.

[0130] 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 1 below.

[0131]

[0132] 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

[0133]

[0134] The experimental results for Experimental Examples 1-1 and 1-2 are summarized in Table 2 below.

[0135]

[0136] Adhesion gf / 25mm Flame retardancy Example 1835V-0 Example 2920V-0 Example 31050V-0

[0137]

[0138] In the flame retardancy test, all of Examples 1 to 3 were confirmed to have flame retardancy performance of V-0 or higher. In addition, in the adhesion test, it was confirmed that the adhesion was measured differently depending on the Example, and it was confirmed that the adhesion slightly increased as the thickness of the fire-resistant adhesive layer (20) increased. In particular, it was confirmed that the fire-resistant adhesive layer (20) satisfied the UL94 V-0 flame retardancy rating and had an adhesion of 800 gf / 25 mm or higher as measured based on ASTM D3330.

[0139]

[0140] Experimental Example 2: Fire Resistance Test

[0141] A fire resistance test was performed on the refractory sheets of Examples 4 to 6. In this case, Example 4 was manufactured by laminating a mica sheet to Example 1 to produce a refractory sheet having a thickness of 450 μm. Similarly, Example 5 was manufactured by laminating a mica sheet to Example 2 to produce a refractory sheet having a thickness of 650 μm. In Example 6, a mica sheet was laminated to Example 3 to produce a refractory sheet having a thickness of 1450 μm.

[0142] In addition, Comparative Example 1 is a case where a 250 μm thick fire-resistant sheet is manufactured by laminating a mica sheet to the adhesive layer (general) of Company 1, and Comparative Example 2 is a case where a 250 μm thick fire-resistant sheet is manufactured by laminating a mica sheet to the adhesive layer (flame retardant) of Company 2.

[0143]

[0144] The fire resistance test method is as follows.

[0145]

[0146] 1) The specimen shall have an area of ​​75mm*75mm and be attached to a 0.7mm thick SUS304 steel plate.

[0147] 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℃.

[0148] 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.

[0149]

[0150] The experimental results for Experimental Example 2 are summarized in Fig. 4 and Table 3 below.

[0151]

[0152] 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, example, 4134145143145, no loss, example, 5135142144147, no loss, example, 676787781, no loss

[0153]

[0154] As a result of the experiment, looking at Examples 4 to 6, it was confirmed that the temperature difference of the refractory sheet of the present invention was greatly reduced compared to SUS304 alone (reference point), and when the thickness of the refractory adhesive layer (10) was 300 μm and 500 μm, the refractory heat-insulating property was almost similar, but when the thickness was 1300 μm, it was confirmed that the refractory heat-insulating property was slightly reduced.

[0155] In addition, it can be confirmed that Comparative Example 1 without a flame retardant and Comparative Example 2 with a flame retardant have somewhat lower fire resistance and heat insulation properties than the fire-resistant sheet of the present invention, and it can be confirmed with the naked eye that the fire-resistant sheets of Comparative Examples 1 and 2 lose their adhesive layers, whereas the fire-resistant sheets of Examples 4 to 6 of the present invention do not lose their adhesive layers.

[0156]

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161]

[0162] The fire-resistant sheet for an electric vehicle battery according to the present invention can simultaneously achieve excellent flame blocking performance and fire resistance.

[0163] In addition, the refractory adhesive layer provides excellent expansion thickness and adhesive strength, 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.

[0164] In addition, the excellent stress dissipation ability due to the foam structure of the refractory adhesive layer effectively absorbs shock and vibration, and acts as an insulating layer that delays heat transfer, so it can act as a more effective protective film when exposed to direct flame or high temperatures.

[0165] 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.

[0166] 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 fire-resistant sheet for an electric vehicle battery, characterized by comprising a synthetic resin, an acrylic monomer, a thermal expansion agent, an inorganic flame retardant, and an additive.

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 content ratio of the above refractory adhesive layer is: A fire-resistant sheet for an electric vehicle battery, characterized in that it comprises 15 to 30 parts by weight of a synthetic resin, 5 to 15 parts by weight of an acrylic monomer, 40 to 70 parts by weight of an inorganic flame retardant, 3 to 15 parts by weight of a thermal expansion agent, and the remainder of additives, for a total of 100 parts by weight of the fire-resistant adhesive layer.

4. 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.

5. In paragraph 1, The above synthetic resin, Any one selected from acrylic resin, epoxy resin, polyvinyl acetal resin, polyvinyl chloride resin, polyolefin resin, and combinations thereof, 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 acrylic monomer is, A fire-resistant sheet for an electric vehicle battery, characterized by being any one selected from among 2-Hydroxypropyl acrylate, 2-Hydroxyethyl acrylate, 4-Hydroxybutyl acrylate, isobornyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, t-butyl acrylate, glycidyl acrylate, dimethylaminoethyl acrylate, acryloylmorpholine, and combinations thereof.

7. In paragraph 1, The thickness of the above flame blocking layer is 50 to 1000 μm, and the thickness of the above fire-resistant adhesive layer is 100 to 3000 μm, characterized in that. Fireproof sheet for electric vehicle batteries.

8. In paragraph 1, The above refractory adhesive layer is, A fire-resistant sheet for electric vehicle batteries, characterized by having an adhesive strength of 800 gf / 25 mm or more as measured according to ASTM D3330 while satisfying the UL94 V-0 flame retardancy rating.

9. In paragraph 1, The above refractory adhesive layer is, A refractory sheet for an electric vehicle battery, further comprising a refractory inorganic substance, wherein the refractory inorganic substance is any one selected from yellow soil, bentonite, kaolin, aluminum hydroxide, aluminum oxide, alumina trihydrate (ATH), magnesium hydroxide, zinc oxide, magnesium oxide, and combinations thereof.

10. In paragraph 1, The content ratio of the above refractory adhesive layer is: A refractory sheet for an electric vehicle battery, characterized in that it further comprises 5 to 20 parts by weight of a refractory inorganic material for a total of 100 parts by weight of the refractory adhesive layer.

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 fireproof sheet for an electric vehicle battery, characterized in that it comprises a synthetic resin, an acrylic monomer, a thermal expansion agent, an inorganic flame retardant, and an additive.

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