A high-temperature expansion thermal insulation composite material, its preparation method and application

Abstract

This invention provides a high-temperature expansion thermal insulation composite material, its preparation method, and its application. The composite material comprises the following parts by weight: 30-50 parts of functionalized acrylate emulsion, 25-40 parts of expandable graphite, 45-60 parts of flame retardant, 15-25 parts of nano-inorganic filler, 1.5-2.5 parts of alkylphenol polyoxyethylene ether phosphate diester salt, 1-2 parts of dimethyl polysiloxane, 15-35 parts of water, and a substrate: a protective film layer. This invention uses functionalized acrylate emulsion as the matrix and, through innovative multi-component composite system, achieves multi-mechanism flame retardant and fireproof effects, ultimately obtaining a high-strength, high-fireproof, and high-thermal-insulation high-temperature expansion thermal insulation composite material. During use, this composite material can adhere well to the top cover and base of a lithium-ion battery casing, placed within the inner layer of the battery casing. It can be composited with unsaturated resin systems or interlayers to prepare battery casing composite materials, reducing vehicle weight, replacing aluminum alloy battery casings, and meeting the fireproof requirements of new energy vehicle battery casings.

Description

Technical Field

[0001] This invention relates to a thermal insulation composite material, and more particularly to a composite material that expands and provides thermal insulation under extreme high-temperature conditions, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of the energy storage industry and new energy vehicles, the market demand for high-performance lithium-ion batteries has continued to rise, while the requirements for "lightweight" and "high power" batteries have become increasingly stringent. However, once a lithium-ion battery experiences thermal runaway, the battery system temperature can soar to over 1300°C. Accompanied by high-pressure airflow and particle impact effects, this can easily lead to damage to the battery casing and explosion, directly threatening people's lives and property, and potentially releasing substances harmful to health and the environment. With people's increasing awareness of fire safety, achieving effective protection against extreme high temperatures, pressure changes, and particle impacts in lithium-ion battery fire scenarios, while simultaneously preventing the spread of harmful substances, has become a critical issue that the industry urgently needs to address.

[0003] The casing of lithium-ion batteries must withstand extreme temperature and pressure surges, as well as particle impacts, known as "particle fires," caused by thermal runaway. Currently, most widely used lithium-ion batteries use aluminum casings, but aluminum has a melting point of only 660°C and is extremely prone to burning through at temperatures as high as 1300°C. When the internal pressure of the battery rises and triggers thermal runaway, "particle fires" erupt with an intensity similar to bullet fire. An aluminum casing alone cannot provide sufficient protection; additional fire-retardant materials are necessary to prevent the escape of flames and hot gases and withstand the multiple impacts of extreme environments.

[0004] Current mainstream fire-retardant materials for lithium-ion batteries all have significant defects: While mica sheet fireproof cloth boasts excellent thermal insulation properties, it is brittle and lacks flexibility. The expansion and contraction of lithium-ion batteries during charging and discharging, along with vibrations from vehicle operation, can easily cause the mica sheets to crack or even break over time. Once the structure is damaged, the fireproof performance will be significantly reduced. Furthermore, mica sheets are difficult to fit tightly into complex battery casings, such as curved or uneven surfaces, easily creating gaps that affect the thermal insulation effect. Simultaneously, its hard and brittle nature makes it prone to producing fragments and burrs during cutting and installation, which may puncture the battery insulation layer and cause a short circuit. To ensure thermal insulation, the mica layer needs to reach a certain thickness, which increases the volume and weight of the battery pack, reducing energy density.

[0005] Fire-retardant intumescent coatings are mature in fire protection of steel structures, but they present significant challenges when adapted to aluminum casings for lithium-ion batteries. In thermal runaway scenarios, the initial expansion temperature of the coating is mostly 180-200℃. The carbon layer structure formed by expansion is not strong enough and is easily blown away by the high-pressure airflow from the battery, resulting in poor stability and ablation resistance. Moreover, the expansion carbon layer of most intumescent coatings has a tolerance limit of less than 1300℃. Under this extreme high temperature, sintering, pulverization, and cracking will occur, the weight loss rate will increase significantly, and the heat insulation capacity will decrease sharply. This will cause the temperature of the back surface of the battery casing to rise rapidly, the mechanical properties will fail, and the fire protection effect cannot be guaranteed.

[0006] While aerogel composites represent a high-end solution for fire protection and thermal insulation of current power batteries, outperforming mica sheets and intumescent coatings in overall performance, their shortcomings are equally undeniable. Aerogels themselves are fragile and prone to pulverization, lacking flexibility. Even when combined with fibers to form felt, their compressive and tensile strengths remain low. The long-term operating temperature limit for most commercial aerogel felts is only 500℃-650℃. Above this temperature, the material deteriorates rapidly, with increased pore size and particle growth leading to higher thermal conductivity and a continuous decline in insulation capacity. Under sustained extreme high temperatures of 1300℃, the organic components of the aerogel decompose, and the inorganic framework is prone to sintering, causing material shrinkage and cracking, ultimately resulting in complete failure of its thermal insulation performance.

[0007] Therefore, developing new fireproof materials that combine ultra-toughness, high temperature resistance, impact resistance, and stable thermal insulation properties, especially by breaking through the performance bottlenecks of existing materials through technologies such as polymer crosslinking, has become the core research direction and future breakthrough focus in the field of lithium-ion battery fire protection. Summary of the Invention

[0008] In order to overcome the shortcomings and deficiencies of existing fire-resistant materials for lithium-ion battery casings under extreme high-temperature conditions, this invention provides a flexible composite material that expands and insulates under extreme high-temperature conditions. In the event of thermal runaway of a lithium-ion battery, it forms an insulating layer and has fire-resistant and heat-insulating effects.

[0009] The technical solution adopted in this invention is as follows: A high-temperature expansion thermal insulation composite material comprises the following materials in parts by weight: 30-50 parts of functionalized acrylate emulsion, 25-40 parts of expandable graphite, 45-60 parts of flame retardant, 15-25 parts of nano-inorganic filler, 1.5-2.5 parts of alkylphenol polyoxyethylene ether phosphate diester salt, 1-2 parts of dimethyl polysiloxane, 15-35 parts of water, and a substrate: a protective film layer. Functionalized acrylate emulsions are synthesized by introducing siloxane groups, ester functional groups, hydroxyl groups, carboxyl groups, N-hydroxymethylacrylamide, epoxy functional groups, epoxy resin segments, or urethane groups into the acrylate molecular chain through copolymerization. Flame retardants include solid flame retardants and organophosphate flame retardants, with the solid flame retardant and organophosphate flame retardant having a mass ratio of 30-40 parts and 15-30 parts, respectively. The solid flame retardant is a core-shell structured solid flame retardant, with the core material being a solid flame retardant and the shell material being chitosan, with a molecular weight in the range of 50,000-300,000. The core-shell structured solid flame retardant is prepared using a "blending-adsorption-crosslinking" method.

[0010] Preferably, the functionalized acrylate emulsion includes: silicone-acrylate copolymer emulsion, vinyl acetate-acrylate copolymer emulsion, self-crosslinking acrylate emulsion, epoxy resin modified acrylate emulsion, or polyurethane modified acrylate emulsion.

[0011] Preferably, the expandable graphite is graphite whose volume can expand to 20-500 times under temperature conditions of 200-1000℃.

[0012] Preferably, the core-shell structured solid flame retardant is one or more of metal hydroxides, ammonium polyphosphates, phosphates, silicates, and zinc borate; the organophosphate flame retardant is one or more of tributyl phosphate, triethyl phosphate, triphenyl phosphate, diphenyltoluene phosphate, diphenylisooctyl phosphate, or reactive phosphates.

[0013] Preferably, the nano-inorganic filler includes one or more of nano-silica, porous nano-zinc oxide, nano-titanium dioxide, porous calcium carbonate, and hollow microspheres.

[0014] Preferably, the protective film layer is silicone rubber coated glass fiber cloth, glass fiber fireproof cloth, basalt fiber fireproof cloth, acrylic fiber fireproof cloth, high silica oxygen fire-resistant fiber cloth, or flame-retardant cloth.

[0015] A method for preparing a high-temperature expansion thermal insulation composite material includes the following steps: Step 1: Mix the functionalized acrylate emulsion, organophosphate flame retardant, and water thoroughly to obtain solution A; Step 2: Chitosan acid solution and solid flame retardant powder are shear-blended at high speed under pH 4.5-5.5 conditions, so that chitosan is initially adsorbed on the surface of flame retardant particles through different forces such as hydrogen bonds, coordination bonds, and electrostatic attraction; then a crosslinking agent is added and slowly stirred, so that chitosan forms a stable network crosslinked shell layer on the surface of flame retardant particles and between particles. The final product is washed and vacuum dried to obtain a solid flame retardant with a core-shell structure.

[0016] Step 3: Thoroughly mix expandable graphite, core-shell structured solid flame retardant, and nano-inorganic filler to obtain mixed powder B; Step 4: Add the mixed powder B obtained in Step 3, alkylphenol polyoxyethylene ether phosphate diester salt and dimethyl polysiloxane to the solution A obtained in Step 1, and stir thoroughly to obtain gel C; Step 5: Apply the gel C obtained in Step 4 onto the protective film layer using a coating machine, and dry it to obtain the composite material.

[0017] Preferably, in step one, the stirring speed is 800 r / min and the stirring time is 3 minutes; in step two, the high-speed shear blending speed is 4000 r / min and the stirring time is 30 minutes; in step three, the mixing speed of the powder is 500 r / min and the stirring time is 5 minutes; and in step four, the stirring speed is 700 r / min and the stirring time is 3 minutes.

[0018] Preferably, the drying temperature in step five is 60°C and the drying time is 6 hours.

[0019] Application of a high-temperature expansion thermal insulation composite material: It can be applied to the fire protection of lithium-ion batteries and to prepare battery casing composite materials.

[0020] The beneficial effects of this invention are as follows: Using functionalized acrylic emulsions as adhesives not only endows composite materials with excellent mechanical stability and flexibility, allowing them to be bent, folded, and twisted, but also ensures good compatibility with various additives. When combined with nano-inorganic fillers, the bonding strength can be flexibly adjusted to meet the needs of flexible products.

[0021] Using solid flame retardants, optimized for compatibility through core-shell coating, and compounded with organophosphate flame retardants, this product achieves highly efficient fireproof and heat insulation with low smoke, no toxicity, and no corrosive gases. At high temperatures, the two work synergistically to form a robust, expanding charred layer and a glassy protective layer, blocking heat and oxygen transfer. The addition of dispersants and defoamers improves surface porosity defects and increases the yield rate.

[0022] Nano-inorganic fillers can improve the fire resistance of composite materials, reduce the ablation rate and shrinkage rate, and can also serve as a carrier for flame retardants to promote their uniform dispersion. At the same time, they can work synergistically with expandable graphite and flame retardants to enhance the stability of the expanded carbon layer skeleton, thereby significantly improving the fireproof and heat insulation effect and fire resistance time.

[0023] The protective film layer endows the composite material with good mechanical strength, flexibility and tensile deformation resistance. It can not only isolate some heat, but also protect the stability of the carbon foam layer formed by high temperature expansion, resist the impact of high pressure airflow, and effectively block the spread of dense smoke, heat and fire.

[0024] Overall, this invention uses functionalized acrylic emulsion as the matrix and innovates through multi-component system composite to form a multi-mechanism flame retardant and fireproof effect, ultimately obtaining a high-strength, high-fireproof, and high-heat-insulating composite material.

[0025] During use, this invention can fit well with the top cover and base of a lithium-ion battery casing, and be placed inside the top cover of the battery casing; or it can be used as a battery heat insulation pad for thermal protection between battery cells, effectively preventing the spread of high temperature between battery cells and providing heat insulation for charging cables. It can also be combined with unsaturated resin systems or interlayers to prepare battery casing composite materials, which can reduce the weight of the vehicle body to a certain extent, replace aluminum alloy battery casings, and meet the corresponding fire protection requirements for new energy vehicle battery casings. Attached Figure Description

[0026] Figure 1 This is a front view of the 1.5mm thick composite material sheet at room temperature in Embodiment 1 of the present invention.

[0027] Figure 2 This is a front view of the roll of the 1.5mm thick composite material at room temperature in Embodiment 1 of the present invention.

[0028] Figure 3 This is a front view of the state of the 1.5mm thick composite material bonded to a 2mm aluminum plate in Example 1 of the present invention after continuous firing at 1300℃ for 30 minutes.

[0029] Figure 4 This is a side view of the state of the 1.5mm thick composite material in Example 1 of the present invention after continuous firing at 1300℃ for 30 minutes.

[0030] Figure 5 The image shows the back aluminum plate and the back of the composite material after the 1.5mm thick composite material was continuously fired at 1300℃ for 30 minutes in Example 1 of this invention.

[0031] Figure 6 This is a front view of the 1.5mm thick composite material in Comparative Example 1 of the present invention after being continuously fired at 1300℃ for 30 minutes. Detailed Implementation

[0032] Example 1 30 parts of functionalized acrylate emulsion vinyl acetate-acrylate copolymer emulsion, 15 parts of organophosphate flame retardant tributyl phosphate, and 35 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0033] 25 parts of expandable graphite, 15 parts of core-shell structured solid flame retardant aluminum hydroxide, 15 parts of ethylenediamine phosphate, and 15 parts of nano-inorganic filler nano-silica were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 1.5 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 1.0 part of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective silicone rubber-coated fiberglass cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a high-temperature expansion and heat insulation composite material.

[0034] Comparative Example 1 30 parts of functionalized acrylate emulsion vinyl acetate-acrylate copolymer emulsion, 15 parts of organophosphate flame retardant tributyl phosphate, and 35 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0035] 25 parts of expandable graphite, 15 parts of core-shell structured solid flame retardant aluminum hydroxide, and 15 parts of ethylenediamine phosphate were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 1.5 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 1.0 part of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed using a mixer at 700 r / min for 3 minutes to obtain gel-like material C. This gel was then coated onto a protective silicone rubber-coated fiberglass cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a high-temperature expansion and heat insulation composite material.

[0036] Example 2 50 parts of functionalized acrylate emulsion organosilicon-acrylate copolymer emulsion, 20 parts of organophosphate flame retardant diphenyltoluene phosphate, and 25 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0037] 40 parts of expandable graphite, 10 parts of core-shell structured solid flame retardant aluminum hydroxide, 10 parts of magnesium hydroxide, 20 parts of melamine phosphate, and 25 parts of nano-inorganic filler nano-titanium dioxide were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 2.5 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 2.0 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective film of high-silica refractory fiber cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a composite material that expands and insulates at high temperatures.

[0038] Comparative Example 2-1 Add 50 parts of functionalized acrylate emulsion silicone-acrylate copolymer emulsion and 25 parts of water to a container, and stir at 800 r / min for 3 min to obtain solution A; Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0039] 40 parts of expandable graphite, 15 parts of solid flame retardant aluminum hydroxide, 15 parts of magnesium hydroxide, 30 parts of core-shell structured solid flame retardant melamine phosphate, and 25 parts of nano-inorganic filler nano-titanium dioxide were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 2.5 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 2.0 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective film of high-silica refractory fiber cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a composite material that expands and insulates at high temperatures.

[0040] Comparative Example 2-2 50 parts of functionalized acrylate emulsion organosilicon-acrylate copolymer emulsion, 30 parts of organophosphate flame retardant diphenyltoluene phosphate, and 25 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0041] 40 parts of expandable graphite, 30 parts of core-shell structured solid flame retardant melamine phosphate, and 25 parts of nano-inorganic filler nano-titanium dioxide were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 2.5 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 2.0 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective film of high-silica refractory fiber cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 h. The resulting composite material was then cut to the required size to obtain a composite material that expands and insulates at high temperatures.

[0042] Comparative Examples 2-3 50 parts of functionalized acrylate emulsion organosilicon-acrylate copolymer emulsion, 30 parts of organophosphate flame retardant diphenyltoluene phosphate, and 25 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0043] 40 parts of expandable graphite, 15 parts of core-shell structured solid flame retardant aluminum hydroxide, 15 parts of magnesium hydroxide, and 25 parts of nano-inorganic filler nano-titanium dioxide were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 2.5 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 2.0 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective film of high-silica refractory fiber cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a composite material that expands and insulates at high temperatures.

[0044] Example 3 45 parts of functionalized acrylic emulsion and epoxy resin modified acrylic emulsion, 18 parts of organophosphate flame retardant diphenyltoluene phosphate and 15 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0045] 40 parts of expandable graphite, 10 parts of core-shell structured solid flame retardant magnesium hydroxide, 20 parts of ammonium polyphosphate, and 18 parts of nano-inorganic filler nano-calcium carbonate were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 2.0 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 1.5 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective acrylic fiber fireproof cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a composite material that expands and insulates at high temperatures.

[0046] Comparative Example 3-1 45 parts of functionalized acrylic emulsion and epoxy resin modified acrylic emulsion, 18 parts of organophosphate flame retardant diphenyltoluene phosphate and 15 parts of water were added to a container and stirred at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0047] 40 parts of expandable graphite, 10 parts of core-shell structured solid flame retardant magnesium hydroxide, 20 parts of ammonium polyphosphate, and 18 parts of nano-inorganic filler nano-calcium carbonate were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B was added to solution A and dispersed and stirred at high speed using a mixer at 700 r / min for 3 minutes to obtain gel C. The gel C was coated onto a protective film acrylic fiber fireproof cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 h. The resulting composite material was then cut into the required size to obtain a composite material that expands and insulates at high temperatures.

[0048] Comparative Example 3-2 Add 45 parts of ordinary acrylic emulsion, 18 parts of organophosphate flame retardant diphenyltoluene phosphate, and 15 parts of water to a container, and stir at 800 r / min for 3 min to obtain solution A. Preparation of core-shell structured solid flame retardant: Dissolve chitosan in 1%-2% dilute acetic acid to prepare a 0.5%-1.5% solution, stir until clear, the pH of this solution is about 3.5-4.5, to ensure that the chitosan is fully protonated and positively charged; slowly adjust the pH of the chitosan solution to 4.5-5.5 with dilute NaOH solution, and slowly add the flame retardant powder to the adjusted chitosan solution under high-speed shear stirring (homogenizer), and continue high-speed shear stirring for 30-60 minutes to fully disperse the particles and allow them to collide and adsorb with chitosan molecules. The above suspension was transferred to a conventional stirrer, and glutaraldehyde aqueous solution (concentration 0.5%-2%) was slowly added dropwise as a crosslinking agent. The amount of glutaraldehyde was 10%-30% of the chitosan mass. The mixture was gently stirred at 40℃-60℃ for 2-4 hours to form a crosslinked network, which encapsulated and fixed the flame retardant particles in the network. The product was centrifuged, filtered, washed, and finally freeze-dried or vacuum-dried at 60℃ to obtain chitosan-coated flame retardant powder.

[0049] 40 parts of expandable graphite, 10 parts of core-shell structured solid flame retardant magnesium hydroxide, 20 parts of ammonium polyphosphate, and 18 parts of nano-inorganic filler nano-calcium carbonate were added to a high-speed mixer and mixed evenly at 500 r / min for 3 min to obtain mixed powder B. Mixed powder B, 2.0 parts of alkylphenol polyoxyethylene ether phosphate diester dispersant, and 1.5 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed at 700 r / min for 3 minutes to obtain gel-like substance C. This gel was then coated onto a protective acrylic fiber fireproof cloth using a coating machine and conveyed to a drying room for hot air drying at 60℃ for 6 hours. The resulting composite material was then cut to the required size to obtain a composite material that expands and insulates at high temperatures.

[0050] Comparative Example 3-3 45 parts of functionalized acrylic emulsion modified with epoxy resin, 18 parts of organophosphate flame retardant diphenyltoluene phosphate, and 15 parts of water were added to a container and stirred at 800 rpm for 3 minutes to obtain solution A. 40 parts of expandable graphite, 10 parts of unmodified or uncoated solid flame retardant magnesium hydroxide, 20 parts of ammonium polyphosphate, and 18 parts of ordinary calcium carbonate were added to a high-speed mixer and mixed at 500 rpm for 3 minutes to obtain mixed powder B. The obtained mixed powder B, 2.0 parts of alkylphenol polyoxyethylene ether phosphate diester salt dispersant, and 1.5 parts of dimethyl polysiloxane defoamer were added to solution A and dispersed and stirred at high speed using a mixer at a speed of 700 r / min for 3 minutes to obtain a gel-like substance C. This substance was then coated onto a protective film acrylic fiber fireproof cloth using a coating machine and conveyed to a drying room for hot air drying at a temperature of 60℃ for 6 hours. The resulting composite material was then cut into the required size to obtain a composite material that provides thermal insulation during high-temperature expansion.

[0051] Comparative Example 4 Ultra-thin fire-retardant intumescent coatings available on the market.

[0052] Comparative Example 5 5mm thick composite fireproof aerogel felt.

[0053] Performance testing of expansion thermal insulation composite materials In the above examples, the prepared intumescent thermal insulation composite material, the commercially available ultrathin fire-retardant intumescent coating of Comparative Example 4, and the 5mm thick composite fire-retardant aerogel felt of Comparative Example 5 were mechanically composited with a 2mm thick aluminum plate, and the following performance tests were conducted: 1. Mechanical bonding test of 2mm aluminum plate: A 1.5mm thick composite material, i.e. a protective film layer, is bonded to one side of a 2mm thick aluminum plate. The plate is then heated at 1300℃ for 30 minutes to observe the changes in the 2mm aluminum plate and the temperature of the back surface of the aluminum plate.

[0054] 2. Expansion coefficient test of composite materials at 1300℃: The expansion coefficient and weight loss rate of composite materials, as well as commercially available ultra-thin fire-retardant expansion coatings and 5mm thick composite fire-retardant aerogel felts, were tested after being fired at 1300℃ for 30 minutes. The expansion coefficient is a multiple of the initial thickness.

[0055] As can be seen from the experimental results in Table 1, the high-temperature expansion and heat insulation flexible composite materials prepared in Examples 1 to 3 of this invention have an expansion coefficient of around 21, high carbon foam stability, and a weight loss rate of less than 50%. Moreover, when a 1.5 mm thick composite material is bonded to a 2 mm aluminum plate and fired at 1300 °C for 30 minutes, the temperature of the back surface of the aluminum plate does not exceed 150 °C within 30 minutes.

[0056] Comparative Example 4, a commercially available ultra-thin fire-retardant intumescent coating, mainly consists of intumescent flame retardants: acid source, carbon source, gas source, functional additives, and resin. A 3mm thick layer of the fire-retardant intumescent coating was applied to a 2mm aluminum plate. After a 30-minute flame test at 1300℃, the aluminum plate showed significant softening. Although the plate was not penetrated and no open flame was observed, the temperature on the unexposed side of the aluminum plate rose sharply, reaching a maximum of 423℃. This was primarily because 1300℃ exceeded the tolerance limit of the intumescent carbon layer in the fire-retardant coating. The resulting carbon layer structure lacked sufficient strength and was easily dispersed by the 1300℃ high-temperature airflow, exhibiting poor stability and ablation resistance. This led to sintering, pulverization, and cracking of the carbon layer, a significant increase in weight loss, and a sharp decrease in heat insulation capacity. Consequently, the temperature on the unexposed side rose sharply, mechanical properties failed, and the fire-retardant effect could not be guaranteed.

[0057] Comparative example 5 of commercially available fire-retardant aerogel felt is mainly composed of inorganic aerogel and fiber substrate. A 5mm thick fire-retardant aerogel felt was mechanically bonded to a 2mm aluminum plate. After a 30-minute flame test at 1300℃, although the aluminum plate was not completely penetrated, it turned noticeably red-hot, and the temperature of the unexposed side rose sharply, reaching a maximum of 552℃. At high temperatures, aerogel materials primarily rely on physical insulation; their nanoporous structure greatly enhances heat conduction, thus delaying heat loss. However, because aerogel itself is very fragile, it easily pulverizes and crumbles under external force, lacking flexibility. Even when combined with fibers to form felt, it only improves flexibility to a certain extent. Since the long-term safe operating temperature of most aerogel felts is around 650℃, exceeding this temperature accelerates material degradation. At a sustained high temperature of 1300℃, the organic components decompose, and the inorganic framework sinters, leading to shrinkage and cracking, thus severely reducing insulation performance and affecting the mechanical properties of the battery casing aluminum plate.

[0058] Based on the results of the composite materials prepared in Example 1 and Comparative Example 1, under the same testing conditions, Comparative Example 1 lacks nano-inorganic fillers compared to Example 1. The coefficient of thermal expansion of the composite material prepared in Comparative Example 1 is slightly larger than that in Example 1. This is mainly because the percentage of expandable graphite in Comparative Example 1 is higher than that in Example 1 due to the absence of nano-inorganic fillers, resulting in a slightly larger coefficient of thermal expansion. Compared to Example 1, Comparative Example 1 exhibits poorer carbon foam stability after combustion. When a 1.5mm thick composite material bonded to a 2mm thick aluminum plate was burned at 1300℃, the carbon layer was loose and unstable, easily scattering under the impact of 1300℃, failing to achieve a good dense heat insulation effect. Consequently, the temperature of the back-fired surface of the aluminum plate in Comparative Example 1 was slightly higher. The main reason is that the nano-inorganic filler can maintain its excellent high-temperature resistance even at 1300℃. Therefore, the addition of the nano-inorganic filler improves the heat resistance of the composite material and reduces the ablation rate. Secondly, the large crystallization shrinkage of the resin emulsion leads to a large shrinkage rate of the composite material. The addition of nano-inorganic filler, which also functions as an activator and reinforcing agent, can effectively increase the volume and strength of the resin, significantly reduce the shrinkage rate of the composite material, improve processing fluidity, and optimize the key mechanical properties of the resin, further improving the mechanical stability of the composite material. Therefore, the weight loss rate of the composite material prepared in Example 1 is lower than that in Comparative Example 1. Thirdly, the nano-inorganic filler can improve the fire resistance of the composite material, reduce the ablation rate and shrinkage rate, and can also act as a flame retardant carrier to promote its uniform dispersion. At the same time, it can synergistically enhance the stability of the expanded carbon layer skeleton with expandable graphite and flame retardant, greatly improving the fireproof and heat insulation effect and fire resistance aging, making the carbon foam layer more stable, dense and heat-insulating after the composite material expands. Therefore, the coefficient of thermal expansion of the composite material in Example 1 is higher than that in Comparative Example 1, the weight loss rate is lower than that in Comparative Example 1, and the temperature of the back-fired surface of the composite material in Example 1 bonded to a 2mm aluminum plate does not exceed 150℃ when tested at 1300℃ for 30 minutes.

[0059] Based on the results of the composite materials prepared in Example 2 and Comparative Examples 2-1, 2-2, and 2-3, under the same testing conditions, Example 2 and Comparative Examples 2-1, 2-2, and 2-3 lacked the corresponding organophosphorus liquid flame retardants, metal hydroxide flame retardants, and phosphate solid flame retardants. The coefficient of thermal expansion of the composite material prepared in Example 2 was greater than that of Comparative Examples 2-1, 2-2, and 2-3. This is mainly due to the multi-component compounding of the flame retardants. The use of solid flame retardants, optimized through core-shell and coating treatments, combined with organophosphorus ester flame retardants, achieves high-efficiency fireproof and heat insulation with low smoke, non-toxicity, and no corrosive gases. At high temperatures, they synergistically form a robust, expanding charred layer and a glassy protective layer, blocking heat and oxygen transfer.

[0060] Based on the results of the composite materials prepared in Example 2 and Comparative Examples 2-1, 2-2, and 2-3, under the same testing conditions, solid flame retardants possess properties such as good thermal stability, non-volatility, and long-lasting effects. Microstructural design, such as core-shell coating, can address the fundamental problems of poor compatibility and easy migration between added solid flame retardants and polymers. However, inorganic flame retardants alone require an addition amount of over 50% to achieve a significant flame-retardant effect. A large filler content inevitably leads to poor flowability of the composite material, affecting its processing and mechanical properties. Therefore, in Comparative Example 2-1, when a 1.5mm thick composite material bonded to a 2mm thick aluminum plate was subjected to a 1300℃ impact test, the carbon foam exhibited poor stability and was prone to scattering, failing to achieve a good dense thermal insulation effect.

[0061] The use of organophosphate flame retardants, in small quantities, provides excellent flame retardant properties. During combustion, it forms a thin, glassy or liquid protective layer on the polymer surface, acting as a heat-insulating and oxygen-barrier, reducing oxygen diffusion and heat transfer between the gas and solid phases, inhibiting carbon oxidation, and effectively isolating the polymer from air. The flame-retardant effect of organophosphate flame retardants lies in promoting dehydration and carbonization during the initial decomposition of the composite material. This dehydration and carbonization relies on the oxygen-containing groups in the resin emulsion itself, which is essential for polymers with inherent oxygen-containing groups in their structure. Therefore, the composite materials in Comparative Examples 2-2 and 2-3 exhibit better carbon foam stability after combustion. Furthermore, in the test of burning a 1.5mm thick composite material bonded to a 2mm thick aluminum plate, no carbon foam dispersion was observed under impact at 1300℃, demonstrating better flame retardant and heat insulation effects than Comparative Example 2-1.

[0062] However, when organophosphate flame retardants are combined with metal hydroxides, phosphates or silicates, they can produce a significant "1+1>2" synergistic flame retardant effect. This synergistic flame retardant effect mainly comes from the complementarity and enhancement in the gas phase and condensed phase, resulting in a better flame retardant effect and a better expansion insulation effect.

[0063] The crystalline water vapor and non-combustible gas produced by the high-temperature decomposition of solid flame retardants dilute the concentration of oxygen and combustible gases, absorb a certain amount of heat, and inhibit the spread of combustion. At the same time, the generated metal oxides catalyze the thermo-oxidative crosslinking reaction of the resin emulsion, and the organophosphate flame retardants promote the dehydration and carbonization of the composite material during the initial decomposition. Together, they form a strong, porous phosphorus-carbon hybrid barrier on the polymer surface, effectively isolating heat and combustibles.

[0064] Therefore, multi-component formulations of flame retardants, using solid flame retardants and optimized for compatibility through core-shell coating, combined with organophosphate flame retardants, offer higher efficiency and more comprehensive functions. Compared to high-volume additions of single flame retardants, the synergistic system has less impact on the mechanical and processing properties of the substrate, achieving highly efficient fireproofing and heat insulation with low smoke, no toxicity, and no corrosive gases. At high temperatures, the synergistic effect forms a robust, expanding char layer and a glassy protective layer, blocking heat and oxygen transfer.

[0065] Based on the results of the composite materials prepared in Example 3 and Comparative Example 3-1, under the same testing conditions, Comparative Example 3 and Example 3-1 lacked the corresponding emulsifiers and defoamers. The composite material prepared in Example 3 had a uniform surface and no bubbles or pores in its internal cross-section. Comparative Example 3-1, due to the lack of emulsifiers and defoamers, had an uneven surface and bubbles and pores in its internal cross-section. This was mainly because the lack of emulsifiers and defoamers caused a strong repulsion between the hydrophilic powder and the hydrophobic emulsion during the mixing process, resulting in uneven distribution of the flame-retardant components in the emulsion, poor adhesion to the matrix, and the formation of an unstable slurry. Simultaneously, some air was introduced during the stirring process, leading to pores and gaps in the composite material coating process, thus reducing the product's pass rate.

[0066] Based on the results of the composite materials prepared in Example 3 and Comparative Example 3-2, under the same testing conditions, the emulsion used in Comparative Example 3-2 was an unmodified ordinary acrylic emulsion. After burning a 1.5 mm thick composite material with a 2 mm thick aluminum plate at a high temperature of 1300°C, the carbon layer of Example 3 was more stable and denser than that of Comparative Example 3-2, and the flame retardant and heat insulation effect was better. This is mainly because during the combustion of Comparative Example 3-2, the synergistic effect between the decomposition of the acrylic emulsion and the reaction with the flame retardant was not great, the char structure was relatively loose, and the flame retardant and heat insulation efficiency was limited, and the temperature of the unexposed side of the aluminum plate was more likely to rise. The modified acrylate emulsion is rich in active functional groups such as epoxy and hydroxyl groups. The active functional groups of the resin crosslink with ammonium polyphosphate and other catalysts to form a dense and high-strength skeletal carbon layer. Magnesium hydroxide and calcium carbonate can be stably embedded in it. The modified system gives fuller play to the synergistic effect of the "phosphorus-nitrogen-magnesium-calcium" multi-component, which greatly improves the interfacial strength and prevents the flame retardant from peeling off from the matrix at high temperatures. As a result, the carbon layer formed is of higher quality and has better heat insulation and oxygen barrier effects.

[0067] Based on the results of the composite materials prepared in Example 3 and Comparative Example 3-3, under the same testing conditions, in Comparative Example 3-3, the uncoated flame retardant and ordinary calcium carbonate, during mixing, showed that ordinary calcium carbonate only served as a filler, while nano-calcium carbonate functioned as both an activator and a reinforcing agent, effectively improving the resin's strength, processing fluidity, and optimizing its key mechanical properties. Core-shell coating primarily addresses the fundamental issues of chemical compatibility and reaction, determining whether the flame retardant forms a robust chemical system with the modified resin. The uncoated flame retardant's hydrophilic surface groups create strong interfacial tension with the resin containing hydrophobic segments and epoxy polar groups. This not only leads to agglomeration but also prevents effective char formation during combustion. Uncoated ammonium polyphosphate decomposes prematurely, while epoxy resin requires high temperatures to crosslink and char. This imbalance in their processes prevents synergistic effects. Although emulsifiers and defoamers were added, the emulsifiers could reduce interfacial tension, facilitate initial dispersion, slow down sedimentation, and make it easier for flame retardant particles to be "stirred" into the resin to form a homogeneous mixture. However, agglomeration still occurred. The defoamers could eliminate large air bubbles introduced during stirring, solve quality problems related to material appearance and defects, and ensure a flawless surface. However, they could not solve the microscopic defects caused by agglomerates and weak interfaces. Therefore, emulsifiers and defoamers mainly improved the processing technology and appearance, but they were powerless to address the key chemical interface bonding between the flame retardant and the resin. As a result, performance differences still existed. Consequently, the composite material prepared in Comparative Example 3-3 exhibited a loose char layer structure, cracks and pores, and was unable to effectively insulate against heat and oxygen during combustion. It also had poor expansion effect, resulting in a higher temperature on the unexposed side of the aluminum plate.

[0068] In this invention, acrylate emulsion is used as the matrix, and functionalized acrylic resin is preferred as a high-quality adhesive with excellent performance, giving it additional properties beyond basic bonding and film formation, resulting in a composite material with excellent mechanical stability.

[0069] The multi-component compounding of flame retardants offers higher efficiency and more comprehensive functions. Compared to high addition amounts of a single flame retardant, the synergistic system has less impact on the mechanical and processing properties of the substrate, achieving highly efficient fireproofing and heat insulation with low smoke, no toxicity, and no corrosive gases. At high temperatures, the synergistic effect forms a robust, expanding char layer and a glassy protective layer, blocking heat and oxygen transfer.

[0070] Adding nano-inorganic fillers, which function as both activators and reinforcing agents, can effectively increase the volume and strength of the resin, significantly reduce the shrinkage rate of the composite material, improve processing fluidity, and optimize the key mechanical properties of the resin, further enhancing the mechanical stability of the composite material. At the same time, it can improve the fire resistance of the composite material, reduce the ablation rate and shrinkage rate, and also act as a flame retardant carrier to promote its uniform dispersion. In addition, it can synergistically enhance the stability of the expanded carbon layer skeleton with expandable graphite and flame retardants, greatly improving the fireproof and heat insulation effect and fire resistance aging, making the carbon foam layer more stable, dense and heat-insulating after the composite material expands.

[0071] A composite material was prepared by adding liquid phosphate ester flame retardants, core-shell coated solid flame retardants, and porous nano-inorganic fillers. This composite material was then coated onto a glass fiber cloth protective film. The protective film acts as a fire barrier for the entire composite material, giving it better mechanical strength, tensile deformation resistance, and good flexibility. The protective film also isolates some of the heat. As the heat increases, the expanding portion rapidly expands at high temperature, increasing in volume and forming a multi-microporous carbon foam layer. This effectively isolates the high-pressure airflow impact from the battery. The protective film effectively protects the stability of the carbon foam after the composite material expands under the runaway flame, further improving the fire resistance of the composite material. This isolates the dense smoke and heat from outside the area, thus blocking the fire and preventing its further spread.

[0072] This invention features a composite innovation that forms a multi-mechanism flame-retardant and fire-resistant composite material, thereby achieving high strength, high fire resistance, and high heat insulation.

[0073] Table 1 Performance Tests of Expandable Thermal Insulation Composite Materials

Claims

1. A high-temperature expansion thermal insulation composite material, characterized in that, The product comprises the following materials by weight: 30-50 parts of functionalized acrylate emulsion, 25-40 parts of expandable graphite, 45-60 parts of flame retardant, 15-25 parts of nano-inorganic filler, 1.5-2.5 parts of alkylphenol polyoxyethylene ether phosphate diester salt, 1-2 parts of dimethyl polysiloxane, 15-35 parts of water, and a substrate: a protective film layer. The functionalized acrylate emulsion is synthesized by introducing siloxane groups, ester functional groups, hydroxyl groups, carboxyl groups, N-hydroxymethylacrylamide, epoxy functional groups, epoxy resin segments or urethane groups into the acrylate molecular chain through a copolymerization reaction. The flame retardant includes a solid flame retardant and an organophosphate flame retardant, with the solid flame retardant and the organophosphate flame retardant having a mass ratio of 30-40 parts and 15-30 parts, respectively. The solid flame retardant is a core-shell structured solid flame retardant, with the shell material being chitosan and a molecular weight in the range of 50,000-300,000. The core-shell structured solid flame retardant is prepared using a "blending-adsorption-crosslinking" process.

2. The high-temperature expansion thermal insulation composite material according to claim 1, characterized in that, The functionalized acrylate emulsions include: silicone-acrylate copolymer emulsions, vinyl acetate-acrylate copolymer emulsions, self-crosslinking acrylate emulsions, epoxy resin modified acrylate emulsions, or polyurethane modified acrylate emulsions.

3. The high-temperature expansion thermal insulation composite material according to claim 1, characterized in that, The expandable graphite is graphite whose volume can expand to 20-500 times under temperature conditions of 200-1000℃.

4. The high-temperature expansion thermal insulation composite material according to claim 1, characterized in that, The core-shell structured solid flame retardant is one or more of metal hydroxides, ammonium polyphosphates, phosphates, silicates, and zinc borate; the organophosphate flame retardant is one or more of tributyl phosphate, triethyl phosphate, triphenyl phosphate, diphenyltoluene phosphate, diphenylisooctyl phosphate, or reactive phosphates.

5. The high-temperature expansion thermal insulation composite material according to claim 1, characterized in that, The nano-inorganic filler includes one or more of the following: nano-silica, porous nano-zinc oxide, nano-titanium dioxide, porous calcium carbonate, and hollow microspheres.

6. The high-temperature expansion thermal insulation composite material according to claim 1, characterized in that, The protective film layer is made of silicone rubber coated glass fiber cloth, glass fiber fireproof cloth, basalt fiber fireproof cloth, acrylic fiber fireproof cloth, high silica oxygen fire-resistant fiber cloth, or flame-retardant cloth.

7. A method for preparing a high-temperature expansion thermal insulation composite material as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Mix the functionalized acrylate emulsion, organophosphate flame retardant, and water thoroughly to obtain solution A; Step 2: Chitosan acid solution and solid flame retardant powder are shear-blended at high speed under pH 4.5-5.5 conditions, so that chitosan is initially adsorbed on the surface of flame retardant particles through hydrogen bonds, coordination bonds or electrostatic attraction. Then, a crosslinking agent is added and the mixture is slowly stirred to form a stable network crosslinked shell layer of chitosan on the surface of flame retardant particles and between particles. The final product is washed and vacuum dried to obtain a solid flame retardant with a core-shell structure. Step 3: Thoroughly mix expandable graphite, core-shell structured solid flame retardant, and nano-inorganic filler to obtain mixed powder B; Step 4: Add the mixed powder B obtained in Step 3, alkylphenol polyoxyethylene ether phosphate diester salt and dimethyl polysiloxane to the solution A obtained in Step 1, and stir thoroughly to obtain gel C; Step 5: Apply the gel-like substance C obtained in Step 4 onto the protective film layer using a coating machine, and dry it to obtain the composite material.

8. The method for preparing a high-temperature expansion thermal insulation composite material according to claim 7, characterized in that, In step one, the stirring speed is 800 r / min and the stirring time is 3 minutes; in step two, the high-speed shear blending speed is 4000 r / min and the stirring time is 30 minutes; in step three, the mixing speed of the powder is 500 r / min and the stirring time is 5 minutes; in step four, the stirring speed is 700 r / min and the stirring time is 3 minutes.

9. The method for preparing a high-temperature expansion thermal insulation composite material according to claim 7, characterized in that, In step five, the drying temperature is 60℃ and the time is 6 hours.

10. The application of a high-temperature expansion thermal insulation composite material as described in any one of claims 1-6.

Images