Composite fireproof material, preparation method and application thereof

Abstract

The application belongs to the technical field of fireproof and heat-insulating materials, and particularly relates to a composite fireproof material and a preparation method and application thereof. The composite fireproof material is composed of a polyurethane foam matrix and an alumina fiber reinforced material. The alumina fiber reinforced material is an alumina fiber grid coated with a copper plating layer on the surface. The alumina fiber reinforced material is arranged in parallel in the in-plane direction in the polyurethane foam matrix.

Description

Technical Field

[0001] This invention belongs to the field of fireproof and heat-insulating materials technology, and particularly relates to a composite fireproof material, its preparation method and application. Background Technology

[0002] With the continuous upgrading of my country's power grid capacity, the rapid development of the new energy vehicle industry, and the continuous advancement of aerospace technology, fire safety issues at key nodes in power transmission networks, such as cable trench firewalls, thermal management pads for high-energy-density battery packs, and spacecraft thermal protection systems, are becoming increasingly prominent, serving as crucial links in ensuring the stable operation of various high-precision equipment. In these application scenarios, polyurethane foam and other polymer materials are traditionally used as the base materials for firewalls or thermal insulation buffer components. Polyurethane foam, with its excellent foaming and molding processability, low-density and lightweight characteristics, and basic flame-retardant properties achievable by adding conventional flame retardants, holds a significant market share in the fireproofing and insulation field. However, as modern equipment increasingly demands higher levels of integration, power density, and longer service life, unprecedented challenges are posed to the comprehensive performance of fireproof and thermal insulation materials. Traditional single-component homogeneous polyurethane foam materials are gradually revealing their inherent performance shortcomings in complex service environments, making it difficult to meet the stringent safety and energy efficiency requirements of modern industry.

[0003] Specifically, traditional polyurethane foam materials face two major technical defects that are difficult to overcome in long-term operation. First, as a typical polymeric insulation material, polyurethane has an extremely low intrinsic thermal conductivity. While this characteristic is beneficial in preventing the spread of flames and external heat during a fire, it severely hinders the dissipation of the large amount of heat generated by cables or battery cells during normal equipment operation. This leads to long-term heat accumulation inside the firewall, easily forming localized hot spots. This not only accelerates the aging of cable insulation or surrounding components but also creates more serious safety hazards and fire hazards. Second, polyurethane foam materials themselves have relatively poor mechanical properties and insufficient structural rigidity. Under long-term environmental temperature changes, foundation settlement, or external impacts, the foam matrix is ​​prone to volume shrinkage and even macroscopic cracking. Once penetrating cracks form inside the material, these gaps directly become channels for flames and high-temperature smoke to penetrate during a fire, causing the entire firewall to fail completely. To address these pain points, existing technological improvements often focus on compromises in optimizing single properties. For example, to improve thermal conductivity, large amounts of highly thermally conductive inorganic fillers such as boron nitride, silicon carbide, and alumina are incorporated; or short-cut fibers and particles are added to enhance mechanical properties. However, isotropic high-filler composition, while increasing thermal conductivity, significantly impairs the material's insulating properties and easily disrupts the foam pore structure, leading to further degradation of mechanical properties. Randomly distributed short-cut reinforcing phases, on the other hand, struggle to form a continuous, directional load-bearing network, offering limited improvement in crack resistance and often accompanied by serious problems such as weak interfacial bonding and stress concentration.

[0004] In summary, existing modification technologies struggle to synergistically resolve the contradictions between heat dissipation and insulation, and between strength and flame retardancy, within a single homogeneous material system. Therefore, there is an urgent need in this field to develop a novel composite material structure that overcomes the isotropic limitations of traditional homogeneous foam materials. This structure should create a material system capable of efficient thermal conductivity in a specific direction to quickly dissipate localized heat buildup within internal equipment, while maintaining extremely low thermal conductivity in another critical direction to provide excellent fire and heat insulation. Furthermore, the development of a robust and continuous stress transfer and load-bearing network within this polymer matrix is ​​crucial to fundamentally overcome the matrix's tendency to shrink and crack, thereby maintaining structural integrity under complex mechanical stress and thermal shock, and achieving a perfect balance between mechanical strength, efficient thermal conductivity, and durable fire and heat insulation. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a composite fireproof material, its preparation method, and its application.

[0006] Firstly, a composite fire-resistant material, employing the following technical solution: A composite fireproof material, wherein the composite fireproof material is composed of a polyurethane foam matrix and an alumina fiber reinforcement material; The alumina fiber reinforcement material is an alumina fiber mesh with a copper plating layer on the surface; The alumina fiber reinforcement material is arranged in a parallel in-plane orientation within the polyurethane foam matrix.

[0007] Furthermore, the copper layer is a continuous metal plating layer bonded to the surface of the alumina fiber mesh by a chemical copper plating process; the mass of the alumina fiber reinforcing material accounts for 10wt% to 30wt% of the total mass of the composite fireproof material.

[0008] Furthermore, the polyurethane foam matrix is ​​formed by foaming and curing a premix and a polyisocyanate; the raw materials of the premix, by weight, include the following components: 30 to 50 parts by weight of polyol, 5 to 15 parts by weight of flame retardant, 2 to 8 parts by weight of catalyst, 1 to 5 parts by weight of foaming agent, 5 to 15 parts by weight of expandable graphite, 5 to 15 parts by weight of ammonium polyphosphate, and 10 to 30 parts by weight of inorganic flame retardant filler; the amount of polyisocyanate added is 25 to 45 parts by weight per 100 parts by weight of the premix.

[0009] Furthermore, the polyol is selected from at least one of polyether polyols, polyester polyols, and polycarbonate polyols; The inorganic flame-retardant filler is selected from at least one of magnesium hydroxide and aluminum hydroxide; The flame retardant is selected from at least one of dimethyl methylphosphonate, tri(1-chloro-2-propyl) phosphate, and triethyl phosphate; The catalyst is selected from at least one of organotin catalysts and tertiary amine catalysts; The foaming agent is selected from at least one of water, cyclopentane, and fluorinated hydrocarbons; The polyisocyanate is selected from at least one of polydiphenylmethane diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

[0010] Secondly, a method for preparing a composite fire-resistant material adopts the following technical solution: A method for preparing a composite fire-resistant material includes the following steps: Step (1): After pretreatment of the alumina fiber mesh, it is immersed in the chemical copper plating solution to carry out an autocatalytic reduction reaction, and a metallic copper plating layer is deposited on the surface of the alumina fiber. After cleaning and drying, the alumina fiber reinforced material is obtained. Step (2): After dehydrating the polyol, it is mixed evenly with flame retardant, catalyst, foaming agent, expandable graphite, ammonium polyphosphate and inorganic flame retardant filler to obtain premix. Step (3): The alumina fiber reinforced material obtained in step (1) is laid in a molding mold in a parallel in-plane direction. The premixed material obtained in step (2) is mixed with polyisocyanate and then injected into the molding mold with the reinforced material. The mixture foams, expands and wraps the reinforced material in the mold. After heat preservation and curing, the composite fireproof material is obtained.

[0011] Further, in step (1), the pretreatment sequentially includes heat treatment, alkaline washing, sensitization and activation; The heat treatment conditions are: treatment at 350℃~450℃ for 0.5h~2h; The alkaline washing conditions are: treatment with a 15.0 mol / L to 25.0 mol / L potassium hydroxide aqueous solution at a temperature of 40℃ to 60℃ for 10 min to 20 min; The sensitization conditions are: treatment with a 0.2 mol / L to 0.8 mol / L stannous chloride aqueous solution at a temperature of 20℃ to 30℃ for 10 min to 20 min; The activation conditions are: treatment with a 0.5 mol / L to 1.5 mol / L silver nitrate aqueous solution at a temperature of 20 to 30°C for 5 to 15 minutes.

[0012] Further, in step (1), the chemical copper plating solution contains the following components by mass percentage: 1.0%~2.0% inorganic copper salt, 3.0%~5.0% complexing agent, 2.0%~4.0% reducing agent, and the balance is water; The conditions for the autocatalytic reduction reaction are: reaction at a constant temperature of 50℃~70℃ for 5min~20min; The drying conditions are as follows: drying under vacuum at a temperature of 70℃~90℃ for 5~20 minutes.

[0013] Further, in step (2), the dehydration treatment conditions are: vacuum distillation for 1.5h to 3h at 110℃~130℃ and a vacuum degree of -0.08MPa~-0.12MPa; The mixing conditions are: stirring at a speed of 300 r / min to 800 r / min for 20 min to 40 min.

[0014] Furthermore, in step (3), the mixing time of the premix and the polyisocyanate is 30s~90s; The conditions for heat preservation and curing are: heat preservation at a temperature of 40℃~50℃ for 12h~36h.

[0015] Thirdly, the application of a composite fire-resistant material adopts the following technical solution: Application of a composite fireproof material in the preparation of cable trench firewalls, battery pack thermal management gaskets, or spacecraft thermal protection systems.

[0016] The beneficial effects of this invention are: This invention provides a composite fireproof material that incorporates an alumina fiber mesh coated with a copper layer as a reinforcing material into a polyurethane foam matrix. This mesh is oriented parallel to the in-plane direction, creating a multi-scale synergistic reinforcement and anisotropic thermal conductivity network structure. At the microscopic interface, the dense copper coating significantly reduces the interfacial thermal resistance between the insulating alumina fibers and the polyurethane matrix, and utilizes the excellent thermal conductivity of copper to establish an efficient phonon transport channel. Secondly, at the macroscopic structure, the in-plane orientation of the reinforcing material forms a continuous thermally conductive and load-bearing skeleton in the in-plane direction parallel to the fibers, rapidly diffusing locally accumulated heat to the periphery and improving in-plane heat dissipation efficiency. In the inter-plane direction perpendicular to the fibers, the polyurethane foam's porous structure effectively blocks heat, maintaining an extremely low thermal conductivity, thus meeting the dual requirements of efficient heat dissipation and durable insulation. Meanwhile, this directionally arranged continuous fiber-metal composite mesh constructs a strong mechanical transmission path within the matrix. When the material is subjected to thermal stress or external impact, the gradient bonding interface formed by the copper plating on the surface can effectively disperse and transfer the load, absorb destructive energy, and thus significantly inhibit the initiation and propagation of microcracks within the polyurethane matrix. This physical mechanism fundamentally endows the foam matrix with excellent tensile strength, elastic modulus, and crack resistance, ensuring the long-term mechanical integrity and safety reliability of the fireproof isolation structure under complex working conditions. Detailed Implementation

[0017] The following detailed description, in conjunction with embodiments, illustrates the composite fire-retardant material, its preparation method, and its application according to the present invention. For the sake of simplicity, this document cannot exhaustively list all alternative technical features and embodiments included in the present invention. Therefore, those skilled in the art should understand that any technical feature and embodiment within this embodiment does not limit the scope of protection of the present invention. The scope of protection includes all alternative technical features and embodiments adopted by those skilled in the art without inventive effort. Specifically, any embodiment obtained by replacing any technical feature in the present invention or by combining any two or more technical features provided by the present invention should be within the scope of protection of the present invention.

[0018] Example Example 1 This embodiment 1 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 20 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0019] This embodiment 1 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 400 °C for 1 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a concentrated potassium hydroxide aqueous solution (approximately 19.1 mol / L) at 50 °C for 15 min for alkaline washing; after washing, it was sensitized in a stannous chloride aqueous solution (0.5 mol / L) at 25 °C for 15 min; after washing, it was then activated in a silver nitrate aqueous solution (1 mol / L) at 25 °C for 10 min; after each step, it was thoroughly washed with deionized water.

[0020] Preparation of the electroless copper plating solution: Weigh 1.5 g of anhydrous copper sulfate as the inorganic copper salt, 4.0 g of sodium tartrate as the complexing agent, and measure 2.5 mL of formaldehyde as the reducing agent. Dissolve all three in 90 g of deionized water and stir thoroughly. Immerse the activated fiber mesh in the electroless copper plating solution and perform a self-catalytic reduction reaction in a 60 ℃ constant temperature water bath for 10 min, allowing copper ions to be reduced on the fiber surface to form a dense copper coating. After the reaction is complete, remove the fiber, rinse it with deionized water, and then dry it in an 80 ℃ vacuum oven for 10 min to obtain the alumina fiber reinforced material.

[0021] Step (2), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 120 °C and -0.1 MPa for 2 h. After cooling, the dehydrated polyether polyol, dimethyl methyl phosphate, organotin catalyst, expandable graphite, ammonium polyphosphate, magnesium hydroxide, aluminum hydroxide, and deionized water were weighed out in a mass ratio of 38:11:5:11:11:11:11:2 and placed in a beaker. The mixture was stirred at 500 r / min for 30 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0022] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 35 g of polymeric diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 1 min to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 45 ℃ forced-air drying oven and cured for 24 h. After curing, the material was demolded to obtain the composite fireproof material.

[0023] Example 2 This embodiment 2 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 10 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0024] This embodiment 2 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 350 °C for 0.5 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 40 °C potassium hydroxide aqueous solution (15.0 mol / L) for 10 min for alkaline washing; after washing, it was sensitized in a 20 °C stannous chloride aqueous solution (0.2 mol / L) for 10 min; after washing, it was then activated in a 20 °C silver nitrate aqueous solution (0.5 mol / L) for 5 min; after each step, it was thoroughly washed with deionized water.

[0025] Preparation of the electroless copper plating solution: Weigh 1.0 g of anhydrous copper sulfate as the inorganic copper salt, 3.0 g of sodium tartrate as the complexing agent, and measure 2.0 mL of formaldehyde as the reducing agent. Dissolve all three in 94.0 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform an autocatalytic reduction reaction in a 50 ℃ constant temperature water bath for 5 min, allowing copper ions to be reduced on the fiber surface to form a dense copper coating. After the reaction is complete, remove the fiber, rinse it with deionized water, and then dry it in a 70 ℃ vacuum oven for 5 min to obtain the alumina fiber reinforced material.

[0026] Step (2), preparation of polyurethane premix: Polyester polyol was dehydrated by vacuum distillation at 110 °C and -0.08 MPa for 1.5 h. After cooling, the dehydrated polyester polyol, triethyl phosphate, tertiary amine catalyst, cyclopentane, expandable graphite, ammonium polyphosphate, and magnesium hydroxide were weighed out in a mass ratio of 30:5:2:1:5:5:10 and placed in a beaker. The mixture was stirred at 300 r / min for 20 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0027] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 25 g of diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 30 seconds to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 40 ℃ forced-air drying oven and cured for 12 h. After curing, the material was demolded to obtain the composite fireproof material.

[0028] Example 3 This embodiment 3 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 30 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0029] This embodiment 3 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 450 °C for 2 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 60 °C potassium hydroxide aqueous solution (25.0 mol / L) for 20 min for alkaline washing; after washing, it was sensitized in a 30 °C stannous chloride aqueous solution (0.8 mol / L) for 20 min; after washing, it was then activated in a 30 °C silver nitrate aqueous solution (1.5 mol / L) for 15 min; after each step, it was thoroughly washed with deionized water.

[0030] Preparation of the electroless copper plating solution: Weigh 2.0 g of anhydrous copper sulfate as the inorganic copper salt, 5.0 g of sodium tartrate as the complexing agent, and measure 4.0 mL of formaldehyde as the reducing agent. Dissolve all three in 89.0 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform an autocatalytic reduction reaction in a 70 ℃ constant temperature water bath for 20 min, allowing copper ions to be reduced on the fiber surface to form a dense copper coating. After the reaction is complete, remove the fiber, rinse it with deionized water, and then dry it in a 90 ℃ vacuum oven for 20 min to obtain the alumina fiber reinforced material.

[0031] Step (2), preparation of polyurethane premix: Polycarbonate polyol was dehydrated by vacuum distillation at 130 °C and -0.12 MPa for 3 h. After cooling, the dehydrated polycarbonate polyol, tris(1-chloro-2-propyl) phosphate, organotin catalyst, fluorinated hydrocarbon compound, expandable graphite, ammonium polyphosphate, and aluminum hydroxide were weighed in a mass ratio of 50:15:8:5:15:15:30 and placed in a beaker. The mixture was stirred at 800 r / min for 40 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0032] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 45 g of toluene diisocyanate was added. The mixture was stirred rapidly for 90 s to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 50 ℃ forced-air drying oven and cured for 36 h. After curing, the material was demolded to obtain the composite fireproof material.

[0033] Example 4 This embodiment 4 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 15 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0034] This embodiment 4 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 380 ℃ for 1.2 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 45 ℃ potassium hydroxide aqueous solution (concentration 18.0 mol / L) for 12 min for alkaline washing; after washing, it was sensitized in a 22 ℃ stannous chloride aqueous solution (concentration 0.4 mol / L) for 12 min; after washing, it was then activated in a 22 ℃ silver nitrate aqueous solution (concentration 0.8 mol / L) for 8 min; after each of the above treatments, it was thoroughly washed with deionized water.

[0035] Preparation of the electroless copper plating solution: Weigh 1.2 g of anhydrous copper sulfate as the inorganic copper salt, 3.5 g of sodium tartrate as the complexing agent, and measure 2.5 mL of formaldehyde as the reducing agent. Dissolve all three in 92.8 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform an autocatalytic reduction reaction in a 55 ℃ constant temperature water bath for 8 min, allowing copper ions to be reduced on the fiber surface to form a dense copper plating layer. After the reaction is complete, remove the fiber, rinse it with deionized water, and then dry it in a 75 ℃ vacuum oven for 8 min to obtain the alumina fiber reinforced material.

[0036] Step (2), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 115 °C and -0.09 MPa for 2 h. After cooling, the dehydrated polyether polyol, dimethyl methylphosphonate, organotin catalyst, water, expandable graphite, ammonium polyphosphate, magnesium hydroxide, and aluminum hydroxide were weighed out in a mass ratio of 40:10:4:3:10:10:15:5 and placed in a beaker. The mixture was stirred at 400 r / min for 25 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0037] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 30 g of polymeric diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 45 s to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 42 ℃ forced-air drying oven and cured for 18 h. After curing, the material was demolded to obtain the composite fireproof material.

[0038] Example 5 This embodiment 5 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 25 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0039] This embodiment 5 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 420 °C for 1.8 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 55 °C potassium hydroxide aqueous solution (22.0 mol / L) for 18 min for alkaline washing; after washing, it was sensitized in a 28 °C stannous chloride aqueous solution (0.6 mol / L) for 18 min; after washing, it was then activated in a 28 °C silver nitrate aqueous solution (1.2 mol / L) for 12 min; after each step, it was thoroughly washed with deionized water.

[0040] Preparation of the electroless copper plating solution: Weigh 1.8 g of anhydrous copper sulfate as the inorganic copper salt, 4.5 g of sodium tartrate as the complexing agent, and measure 3.5 mL of formaldehyde as the reducing agent. Dissolve all three in 90.2 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform an autocatalytic reduction reaction in a 65 ℃ constant temperature water bath for 15 min, allowing copper ions to be reduced on the fiber surface to form a dense copper plating layer. After the reaction is complete, remove the fiber and rinse it with deionized water, then dry it in a vacuum oven at 85 ℃ for 15 min to obtain the alumina fiber reinforced material.

[0041] Step (2), preparation of polyurethane premix: Polyester polyol was dehydrated by vacuum distillation at 125 °C and -0.11 MPa for 2.5 h. After cooling, the dehydrated polyester polyol, triethyl phosphate, tertiary amine catalyst, cyclopentane, expandable graphite, ammonium polyphosphate, and aluminum hydroxide were weighed out in a mass ratio of 45:12:6:4:12:12:25 and placed in a beaker. The mixture was stirred at 600 r / min for 35 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0042] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding mold with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 40 g of isophorone diisocyanate was added. The mixture was stirred rapidly for 75 s to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 48 ℃ forced-air drying oven and cured for 30 h. After curing, the material was demolded to obtain the composite fireproof material.

[0043] Example 6 This embodiment 6 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 12 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0044] This embodiment 6 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 360 °C for 0.8 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 42 °C potassium hydroxide aqueous solution (16.0 mol / L) for 12 min for alkaline washing; after washing, it was sensitized in a 24 °C stannous chloride aqueous solution (0.3 mol / L) for 12 min; after washing, it was then activated in a 24 °C silver nitrate aqueous solution (0.6 mol / L) for 6 min; after each step, it was thoroughly washed with deionized water.

[0045] Preparation of the electroless copper plating solution: Weigh 1.1 g of anhydrous copper sulfate as the inorganic copper salt, 3.2 g of sodium tartrate as the complexing agent, and measure 2.2 mL of formaldehyde as the reducing agent. Dissolve all three in 93.5 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform an autocatalytic reduction reaction in a 52 ℃ constant temperature water bath for 6 min, allowing copper ions to be reduced on the fiber surface to form a dense copper plating layer. After the reaction is complete, remove the fiber, rinse it with deionized water, and then dry it in a 72 ℃ vacuum oven for 6 min to obtain the alumina fiber reinforced material.

[0046] Step (2), preparation of polyurethane premix: Polycarbonate polyol was dehydrated by vacuum distillation at 112 °C and -0.09 MPa for 1.8 h. After cooling, the dehydrated polycarbonate polyol, tris(1-chloro-2-propyl) phosphate, organotin catalyst, fluorinated hydrocarbon compound, expandable graphite, ammonium polyphosphate, and magnesium hydroxide were weighed out in a mass ratio of 35:8:3:2:8:8:15 and placed in a beaker. The mixture was stirred at 350 r / min for 22 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0047] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 28 g of diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 40 seconds to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 41 ℃ forced-air drying oven and cured for 16 h. After curing, the material was demolded to obtain the composite fireproof material.

[0048] Example 7 This embodiment 7 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 28 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0049] This embodiment 7 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 440 °C for 1.8 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 58 °C potassium hydroxide aqueous solution (24.0 mol / L) for 18 min for alkaline washing; after washing, it was sensitized in a 28 °C stannous chloride aqueous solution (0.7 mol / L) for 18 min; after washing, it was then activated in a 28 °C silver nitrate aqueous solution (1.4 mol / L) for 14 min; after each step, it was thoroughly washed with deionized water.

[0050] Preparation of the electroless copper plating solution: Weigh 1.9 g of anhydrous copper sulfate as the inorganic copper salt, 4.8 g of sodium tartrate as the complexing agent, and measure 3.8 mL of formaldehyde as the reducing agent. Dissolve all three in 89.5 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform an autocatalytic reduction reaction in a 68 ℃ constant temperature water bath for 18 min, allowing copper ions to be reduced on the fiber surface to form a dense copper plating layer. After the reaction is complete, remove the fiber and rinse it with deionized water, then dry it in a vacuum oven at 88 ℃ for 18 min to obtain the alumina fiber reinforced material.

[0051] Step (2), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 128 °C and -0.11 MPa for 2.8 h. After cooling, the dehydrated polyether polyol, dimethyl methylphosphonate, tertiary amine catalyst, water, expandable graphite, ammonium polyphosphate, and aluminum hydroxide were weighed out in a mass ratio of 48:14:7:4:14:14:28 and placed in a beaker. The mixture was stirred at 700 r / min for 38 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0052] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 42 g of polymeric diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 80 s to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 49 ℃ forced-air drying oven and cured for 32 h. After curing, the material was demolded to obtain the composite fireproof material.

[0053] Example 8 This embodiment 8 provides a composite fireproof material, which is composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is an alumina fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process. The alumina fiber reinforcement accounts for 18 wt% of the total mass of the composite fireproof material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix, forming a continuous three-dimensional thermally conductive and mechanically load-bearing network.

[0054] This embodiment 8 also provides a method for preparing a composite fireproof material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Alumina fiber mesh measuring 50 cm × 50 cm was placed in a muffle furnace and heat-treated at 400 °C for 1 h to remove residual organic treatment agents from the surface. The heat-treated fiber mesh was then sequentially immersed in a 50 °C potassium hydroxide aqueous solution (20.0 mol / L) for 15 min for alkaline washing; after washing, it was sensitized in a 25 °C stannous chloride aqueous solution (0.5 mol / L) for 15 min; after washing, it was then activated in a 25 °C silver nitrate aqueous solution (1.0 mol / L) for 10 min; after each step, it was thoroughly washed with deionized water.

[0055] Preparation of the electroless copper plating solution: Weigh 1.5 g of anhydrous copper sulfate as the inorganic copper salt, 4.0 g of sodium tartrate as the complexing agent, and measure 3.0 mL of formaldehyde as the reducing agent. Dissolve all three in 91.5 g of deionized water and stir until homogeneous. Immerse the activated fiber mesh in the electroless copper plating solution and perform a self-catalytic reduction reaction in a 60 ℃ constant temperature water bath for 10 min, allowing copper ions to be reduced on the fiber surface to form a dense copper coating. After the reaction is complete, remove the fiber, rinse it with deionized water, and then dry it in an 80 ℃ vacuum oven for 10 min to obtain the alumina fiber reinforced material.

[0056] Step (2), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 120 °C and -0.10 MPa for 2 h. After cooling, the dehydrated polyether polyol, tris(1-chloro-2-propyl) phosphate, organotin catalyst, cyclopentane, expandable graphite, ammonium polyphosphate, magnesium hydroxide, and aluminum hydroxide were weighed out in a mass ratio of 38:11:5:2:11:11:10:10 and placed in a beaker. The mixture was stirred at 500 r / min for 30 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0057] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding mold with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix obtained in step (2) was weighed and 35 g of toluene diisocyanate was added. The mixture was stirred rapidly for 60 s to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforced material. The mixture freely foamed, expanded, and completely enveloped the reinforced material in the mold. The mold filled with the material was then transferred to a 45 ℃ forced-air drying oven and cured for 24 h. After curing, the material was demolded to obtain the composite fireproof material.

[0058] Comparative Example Comparative Example 1 Comparative Example 1 provides a fireproof material, which is pure polyurethane foam without any added reinforcing materials.

[0059] Comparative Example 1 also provides a method for preparing a fire-retardant material, comprising the following steps: Step (1), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 120 °C and -0.1 MPa for 2 h. After cooling, the dehydrated polyether polyol, dimethyl methyl phosphate, organotin catalyst, expandable graphite, ammonium polyphosphate, magnesium hydroxide, aluminum hydroxide, and deionized water were weighed out in a mass ratio of 38:11:5:11:11:11:11:2 and placed in a beaker. The mixture was stirred at 500 r / min for 30 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0060] Step (3), foaming and molding: Weigh 100 g of the premix obtained in step (2) above, add 35 g of polymeric diphenylmethane diisocyanate, and stir rapidly for 1 min to mix evenly. Immediately afterward, pour the mixture into a molding mold with dimensions of 1000 mm × 600 mm × 500 mm. The mixture will freely foam and expand in the mold. Then, transfer the mold filled with the material to a 45°C forced-air drying oven and keep it at that temperature for 24 h to cure. After curing, demold to obtain the fireproof material.

[0061] Comparative Example 2 Comparative Example 2 provides a composite fire-retardant material composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement is a bare alumina fiber mesh without chemical copper plating. The alumina fiber reinforcement accounts for 20 wt% of the total mass of the composite fire-retardant material and is arranged parallel to each other in the in-plane direction within the polyurethane foam matrix.

[0062] Comparative Example 2 also provides a method for preparing a composite fire-resistant material, including the following steps: Step (1), Pretreatment of alumina fiber reinforced material: A 50 cm × 50 cm alumina fiber mesh was placed in a muffle furnace and heat-treated at 400 °C for 1 hour to remove residual organic treatment agents from the surface. Without subsequent alkaline washing, sensitization, activation, or chemical copper plating, the unplated alumina fiber reinforced material was obtained.

[0063] Step (2), preparation of polyurethane premix: Same as step (2) in Example 1.

[0064] Step (3), composite molding: The uncoated alumina fiber mesh processed in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation in the in-plane direction at the bottom of a molding die with dimensions of 1000 mm × 600 mm × 500 mm. 100 g of the premix prepared in step (2) was weighed and 35 g of polymeric diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 1 min to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforcing material. The mixture foamed, expanded, and completely enveloped the reinforcing material. The mold filled with the material was then transferred to a 45 ℃ forced-air drying oven and cured for 24 h. After curing, the material was demolded to obtain the composite fireproof material.

[0065] Comparative Example 3 Comparative Example 3 provides a composite fireproof material composed of a polyurethane foam matrix and an alumina fiber reinforcement. The alumina fiber reinforcement consists of short-cut alumina fibers with a uniform copper plating layer on their surface, achieved through a chemical copper plating process. The short-cut alumina fiber reinforcement accounts for 20 wt% of the total mass of the composite fireproof material and is randomly distributed within the polyurethane foam matrix.

[0066] Comparative Example 3 also provides a method for preparing a composite fire-resistant material, including the following steps: Step (1), Preparation of alumina fiber reinforced material: Same as step (1) in Example 1, but after the reaction is complete, take out the copper-plated fiber mesh, rinse it with deionized water, dry it in a vacuum oven at 80°C for 10 min, and then mechanically crush and cut it into short alumina fibers@copper with a length of 5~10 mm.

[0067] Step (2), preparation of polyurethane premix: Same as step (2) in Example 1.

[0068] Step (3), composite molding: Weigh 100 g of the premix obtained in step (2) above, and add the chopped alumina fiber@copper obtained in step (1) (20 wt% of the total mass of the final material) directly to the premix. Stir with an electric stirrer to disperse it randomly and evenly in the premix. Then add 35 g of polymeric diphenylmethane diisocyanate and stir rapidly for 1 min to mix it evenly. Immediately pour the mixture into a molding mold with dimensions of 1000 mm × 600 mm × 500 mm. The mixture foams and expands freely in the mold. Then transfer it to a 45 ℃ forced-air drying oven and keep it warm for 24 h for curing. After curing, demold to obtain the composite fireproof material.

[0069] Comparative Example 4 Comparative Example 4 provides a composite fireproof material composed of a polyurethane foam matrix, an uncoated alumina fiber mesh, and pure copper powder directly dispersed in the matrix. The total mass of the uncoated alumina fibers and pure copper powder accounts for 20 wt% of the total mass of the composite fireproof material, and the fibers are arranged in a parallel orientation along the in-plane direction.

[0070] Comparative Example 4 also provides a method for preparing a composite fire-retardant material, including the following steps: Step (1), Pretreatment of alumina fibers: Take an alumina fiber mesh with a size of 50 cm × 50 cm, place it in a muffle furnace, and heat treat it at 400 ℃ for 1 hour to remove residual organic treatment agent on the surface, and set it aside for later use.

[0071] Step (2), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 120 °C and -0.1 MPa for 2 h. After cooling, the dehydrated polyether polyol, dimethyl methyl phosphate, organotin catalyst, expandable graphite, ammonium polyphosphate, magnesium hydroxide, aluminum hydroxide, and deionized water were weighed out in a mass ratio of 38:11:5:11:11:11:11:2. Pure copper powder (the amount added was equivalent to the weight ratio of the coating in Example 1) was then added to a beaker. The mixture was stirred at 500 r / min for 30 min using an electric stirrer to form a homogeneous copper-containing premix for later use.

[0072] Step (3), composite molding: The alumina fiber mesh after heat treatment in step (1) was cut into 500 mm × 500 mm sheets and laid in parallel orientation at the bottom of the molding mold. 100 g of the premix prepared in step (2) was weighed and 35 g of polymeric diphenylmethane diisocyanate was added. The mixture was stirred rapidly for 1 min to ensure uniform mixing. The mixture was then immediately poured into the mold containing the reinforcing material for foaming. It was then transferred to a 45 ℃ forced-air drying oven for curing for 24 h. After demolding, the composite fireproof material was obtained.

[0073] Comparative Example 5 Comparative Example 5 provides a composite fire-retardant material composed of a polyurethane foam matrix and alumina fiber reinforcement. No expandable graphite or ammonium polyphosphate is added to the polyurethane premix.

[0074] Comparative Example 5 also provides a method for preparing a composite fire-retardant material, comprising the following steps: Step (1), Preparation of alumina fiber reinforced material: Same as step (1) in Example 1.

[0075] Step (2), preparation of polyurethane premix: The polyether polyol was dehydrated by vacuum distillation at 120 °C and -0.1 MPa for 2 h. After cooling, the dehydrated polyether polyol, dimethyl methyl phosphate, organotin catalyst, magnesium hydroxide, aluminum hydroxide, and deionized water were weighed out in a mass ratio of 60:11:5:11:11:2 and placed in a beaker. The mixture was stirred at 500 r / min for 30 min using an electric stirrer to form a homogeneous polyurethane premix for later use.

[0076] Step (3), composite molding: Same as step (3) in Example 1.

[0077] Comparative Example 6 Comparative Example 6 provides a composite fireproof material, which is basically the same as that in Example 1, except that the mass of the alumina fiber reinforced material accounts for 5 wt% of the total mass of the composite fireproof material.

[0078] Comparative Example 6 also provides a method for preparing a composite fire-retardant material, comprising the following steps: Step (1), Preparation of alumina fiber reinforced material: Same as step (1) in Example 1.

[0079] Step (2), preparation of polyurethane premix: Same as step (2) in Example 1.

[0080] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut and laid in a parallel in-plane direction at the bottom of the molding mold. The overall pouring amount of the premix and isocyanate was adjusted so that the final mass of the alumina fiber reinforced material accounted for only 5 wt% of the total mass of the composite fireproof material. The mixture was allowed to foam and expand freely in the mold. It was then transferred to a 45 ℃ forced-air drying oven for curing for 24 h. After demolding, the composite fireproof material was obtained.

[0081] Comparative Example 7 Comparative Example 7 provides a composite fireproof material, which is basically the same as that in Example 1, except that the mass of the alumina fiber reinforced material accounts for 40 wt% of the total mass of the composite fireproof material.

[0082] Comparative Example 7 also provides a method for preparing a composite fire-retardant material, comprising the following steps: Step (1), Preparation of alumina fiber reinforced material: Same as step (1) in Example 1.

[0083] Step (2), preparation of polyurethane premix: Same as step (2) in Example 1.

[0084] Step (3), composite molding: The alumina fiber reinforced material obtained in step (1) was cut and densely and orientedly laid at the bottom of the molding die. The overall pouring amount of the premix and isocyanate was adjusted so that the final mass of the alumina fiber reinforced material accounted for up to 40 wt% of the total mass of the composite fireproof material. The mixture was foamed and cured in the mold. It was then transferred to a 45 ℃ forced-air drying oven for curing for 24 h. After demolding, the composite fireproof material was obtained.

[0085] Comparative Example 8 Comparative Example 8 provides a composite fireproof material, which is composed of a polyurethane foam matrix and a glass fiber reinforcement material. The glass fiber reinforcement material is a glass fiber mesh with a uniform copper plating layer on its surface obtained through a chemical copper plating process.

[0086] Comparative Example 8 also provides a method for preparing a composite fire-retardant material, comprising the following steps: Step (1), Preparation of glass fiber reinforced material: A standard E-type glass fiber mesh with dimensions of 50 cm × 50 cm was used to replace the alumina fiber mesh. It was placed in a muffle furnace and heat-treated at 400 °C for 1 h. Subsequently, it was sequentially immersed in a concentrated potassium hydroxide aqueous solution at 50 °C for 15 min for alkaline washing; sensitized in a stannous chloride aqueous solution at 25 °C for 15 min; and activated in a silver nitrate aqueous solution at 25 °C for 10 min. Each step involved thorough washing with deionized water.

[0087] Prepare the chemical copper plating solution: Dissolve 1.5 g anhydrous copper sulfate, 4.0 g sodium tartrate, and 2.5 mL formaldehyde in 90 g deionized water. Immerse the activated glass fiber mesh in the copper plating solution and react in a constant temperature water bath at 60 ℃ for 10 min. After washing, dry in a vacuum oven at 80 ℃ for 10 min to obtain the glass fiber@copper reinforced material.

[0088] Step (2), preparation of polyurethane premix: Same as step (2) in Example 1.

[0089] Step (3), composite molding: The glass fiber reinforced material obtained in step (1) was cut into 500 mm × 500 mm sheets and laid in a parallel arrangement at the bottom of the mold. 100 g of the premix from step (2) was weighed and mixed with 35 g of polymeric diphenylmethane diisocyanate before casting. After foaming, the mixture was placed in a 45 ℃ forced-air drying oven for 24 h to cure. After demolding, the composite fireproof material was obtained.

[0090] Application Examples Application Example 1: Application in Cable Trench Firewalls This application example 1 provides a method for applying the composite fireproof material prepared in Example 1 to a high-voltage cable trench firewall, specifically including the following process: (1) Module processing: The large-size composite fireproof material sheet obtained by demolding in Example 1 is processed into matching firewall assembly modules using CNC cutting equipment according to the cross-sectional dimensions of the target cable trench. During the cutting process, the in-plane direction (i.e., the direction in which the alumina fiber reinforcement material is arranged in parallel) and the inter-plane direction (perpendicular to the direction of fiber arrangement) of the material are strictly marked.

[0091] (2) Oriented installation and assembly: In the designated fireproof section of the inner wall of the cable trench, the processed firewall assembly modules are stacked and built. During the building process, the placement direction of the modules is controlled so that the "in-plane direction" of the composite material is perpendicular to the cable direction, that is, the two ends of the fiber face the cable group and the concrete sidewall of the cable trench respectively; at the same time, the "inter-plane direction" of the composite material is parallel to the extension direction of the cable trench.

[0092] (3) Gap sealing and fixing: The gaps between modules and between modules and through-wall cables are sealed with expanding fireproof sealant. External metal brackets are used for auxiliary fixing to prevent the modules from shifting due to long-term foundation settlement.

[0093] The application effect of Example 1 in cable trench firewall: Under normal cable operating conditions, due to the material's high in-plane thermal conductivity of 0.85 W / (m·K), the large amount of heat continuously dissipated by the cable can be quickly and efficiently conducted to the relatively low-temperature concrete trench walls on both sides of the cable trench along the copper-plated fiber network distributed in-plane, and then dissipated. This effectively avoids heat accumulation and the formation of localized hot spots inside traditional polyurethane firewalls, thus delaying the aging of the cable insulation layer. When a fire occurs in a section of the cable trench, the inter-plane thermal conductivity parallel to the trench's direction is only 0.14 W / (m·K), demonstrating the excellent thermal insulation and bridging effect of this composite fireproof material. It can effectively block the conduction of high temperatures from the fire zone to non-fire zones. Simultaneously, the composite fireproof material has a tensile strength of 8.1 MPa, maintaining structural integrity even under high-temperature fire conditions and high-pressure water jet impacts, without shrinkage or cracking. Its limiting oxygen index of 56.1% and UL-94 V-0 flame-retardant performance transform it into a robust fire-resistant and smoke-proof barrier, providing ultimate protection for the safe operation of the power grid.

[0094] Application Example 2: Application in Thermal Management Gaskets for Power Battery Packs in New Energy Vehicles This application example 2 provides a method for applying the composite fire-retardant material prepared in example 4 to a thermal management gasket between battery modules in a new energy vehicle, specifically including the following process: (1) Thin sheet cutting: The composite fireproof material with anisotropic structure prepared in Example 4 is precisely cut along the direction parallel to the internal alumina fiber orientation to prepare a flexible thermal management pad with a thickness of 3 mm ~ 5 mm.

[0095] (2) Surface treatment: In order to meet the insulation requirements in the battery pack and further improve the interface adhesion, a thermally conductive silicone insulating film with a thickness of 10 μm ~ 20 μm is coated on both sides of the gasket after slicing.

[0096] (3) Battery module assembly: When assembling square aluminum-cased battery modules or soft-pack battery modules, the above-mentioned thermal management pads are sandwiched between two adjacent individual cells. During installation, it is necessary to ensure that the "in-plane direction" (high thermal conductivity direction) of the thermal management pads is vertically downward and directly connected to the liquid cooling plate at the bottom of the battery pack; while the "inter-plane direction" (thermal insulation direction) of the pads is facing the surface of the individual cells on both sides.

[0097] (4) Pressure tightening: Apply a certain pre-tightening force to the cell and gasket through the module end plate, and use the elastic deformation of the polyurethane foam matrix to make the gasket and cell surface fit tightly together, eliminating the air gap at the interface.

[0098] The application effect of Example 1 in thermal management gaskets for power battery packs of new energy vehicles: During high-rate charge-discharge cycles of power batteries, the heat generated by the battery cells is first transferred to the gaskets. The gaskets, utilizing their extremely high in-plane thermal conductivity, rapidly conduct the heat downwards to the bottom liquid cooling system, eliminating temperature gradients within the module and maintaining the battery's optimal operating temperature. When an individual battery cell within the module experiences thermal runaway due to internal short circuits or other reasons, resulting in a rapid temperature increase or even fire, the gaskets exhibit excellent thermal insulation in the interfacial direction facing adjacent cells, preventing the lateral spread of heat to adjacent healthy cells. The continuous fiber skeleton within the composite material withstands the mechanical compression caused by the thermal runaway expansion of the battery cells, preventing the gaskets from rupturing. Combined with the synergistic effect of its vapor-phase flame retardancy and the solid-phase flame retardancy of the dense carbon layer on the surface, it successfully blocks the chain propagation of thermal runaway, significantly improving the safety boundary of the battery pack.

[0099] Performance characterization and testing methods To verify the various performance indicators of the composite fireproof material described in this invention, the following test methods were used to characterize the performance of the samples prepared in each embodiment and comparative example: 1. Thermal conductivity test The thermal conductivity of the material was tested using a laser flash thermal conductivity meter (LFA 467, NETZSCH GmbH, Germany). The sample was cut into circular pieces with a diameter of 12.7 mm and a thickness of 2 mm, both parallel to the direction of alumina fiber orientation (in-plane direction) and perpendicular to the direction of fiber orientation (inter-plane direction). The thermal diffusivity of the samples was measured at 25°C. Combined with the sample density and specific heat capacity, the in-plane thermal conductivity (λ∥) and inter-plane thermal conductivity (λ⊥) were calculated.

[0100] 2. Mechanical property testing The tensile properties of the materials were tested using a universal testing machine (AG-X plus, Shimadzu Corporation, Japan) in accordance with ISO 527 or ASTM D638 standards. The demolded composite sheet was cut into standard dumbbell-shaped strips along a plane parallel to the fibers. The tensile rate was set to 5 mm / min, and the tensile strength, modulus of elasticity, and elongation at break of the samples were recorded. Each group of samples was tested in parallel five times, and the average value was taken.

[0101] 3. Flame retardant performance test (1) Limiting Oxygen Index (LOI): According to ASTM D2863 standard, the limiting oxygen index tester (HC-2 type, Nanjing Jiangning Analytical Instrument Factory) was used for testing. The sample size was 130 mm × 10 mm × 10 mm. The minimum oxygen concentration percentage required to maintain stable combustion of the material was determined.

[0102] (2) Vertical flammability rating (UL-94): According to ASTM D3801 standard, the test is conducted using a CZF-3 vertical flammability tester. The sample size is 125 mm × 13 mm × 10 mm. The V-0, V-1 or V-2 rating is determined based on the burning time of the sample and whether there are molten droplets igniting the degreased cotton.

[0103] 4. Thermal stability test (1) Thermal decomposition characteristics: Thermogravimetric analysis (TGA 8000, PerkinElmer, USA) was used to test the temperature at a nitrogen atmosphere with a heating rate of 10℃ / min and a temperature range of 30℃ to 800℃. The temperature corresponding to the maximum weight loss rate was recorded.

[0104] (2) Dimensional stability: The linear expansion coefficient of the sample was tested using a thermomechanical analyzer (TMA 402 F1, NETZSCH, Germany). The heating rate was 5 ℃ / min, and the test temperature range was -50℃ to 150℃. The average linear expansion coefficient was used for comparison.

[0105] Performance test results data table Table 1 below shows the test results of various properties of the fireproof material samples prepared in Examples 1-8 and Comparative Examples 1-8.

[0106] Table 1 Performance test results of the fire-resistant materials provided in Examples 1-8 and Comparative Examples 1-8

[0107] Test Results The test data from Examples 1-8 show that Example 1 exhibits a high in-plane thermal conductivity of 0.85 W / (m·K), significantly improved compared to the matrix material, while maintaining an extremely low inter-plane thermal conductivity of 0.14 W / (m·K), demonstrating excellent anisotropic thermal conductivity. Simultaneously, its tensile strength reaches 8.1 MPa, and its limiting oxygen index is as high as 56.1%, passing the UL-94 V-0 test. Examples 2-8, after adjusting the skeleton addition ratio, polyol matrix type, and copper plating process parameters, although the specific values ​​fluctuated, maintained an in-plane thermal conductivity between 0.62 and 0.98 W / (m·K), and their mechanical strength and flame retardant rating remained at extremely high levels. This fully demonstrates that the directional network system constructed in this invention has a wide process adaptability window and high performance stability.

[0108] Comparative Example 1, consisting of pure polyurethane foam, exhibited extremely poor thermal conductivity and was mechanically very fragile. Comparative Example 2, using uncoated bare fibers, and Comparative Example 4, directly using physically doped copper powder, both showed significantly lower in-plane thermal conductivity than Example 1 (only 0.28 and 0.32 W / (m·K), respectively), and a marked decrease in mechanical strength. This strongly demonstrates the crucial role of the tightly packed metal layer interface constructed by electroless copper plating in reducing interfacial thermal resistance and stress transfer. Comparative Example 3, using randomly dispersed chopped fibers@copper, resulted in an interfacial thermal conductivity of 0.42 W / (m·K) and limited in-plane thermal conductivity, thus losing its anisotropic advantages. Comparative Example 5 removed a specific composite flame-retardant system, leading to a deterioration in flame-retardant performance and revealing the synergistic flame-retardant mechanism between the matrix flame retardant and the skeleton network. Comparative Examples 6 and 7 show that an excessively low proportion of reinforcement cannot construct a continuous network, while an excessively high proportion (40 wt%) destroys the foam pore structure, causing a sharp decrease in elongation at break to 15.5% and loss of interfacial thermal insulation. Comparative Example 8, which used glass fiber, could not achieve the same thermal decomposition temperature and strength as alumina fiber.

[0109] For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, but obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this invention.

Claims

1. A composite fireproof material, characterized in that, The composite fireproof material is composed of a polyurethane foam matrix and alumina fiber reinforcement material. The alumina fiber reinforcement material is an alumina fiber mesh with a copper plating layer on the surface; The alumina fiber reinforcement material is arranged in a parallel in-plane orientation within the polyurethane foam matrix.

2. The composite fireproof material according to claim 1, characterized in that, The copper layer is a continuous metal plating layer bonded to the surface of the alumina fiber mesh by a chemical copper plating process; the mass of the alumina fiber reinforcing material accounts for 10wt% to 30wt% of the total mass of the composite fireproof material.

3. The composite fireproof material according to claim 1, characterized in that, The polyurethane foam matrix is ​​formed by foaming and curing a premix and a polyisocyanate. The raw materials of the premix, by weight, include the following components: 30 to 50 parts by weight of polyol, 5 to 15 parts by weight of flame retardant, 2 to 8 parts by weight of catalyst, 1 to 5 parts by weight of foaming agent, 5 to 15 parts by weight of expandable graphite, 5 to 15 parts by weight of ammonium polyphosphate, and 10 to 30 parts by weight of inorganic flame retardant filler. The amount of polyisocyanate added is 25 to 45 parts by weight per 100 parts by weight of the premix.

4. The composite fireproof material according to claim 3, characterized in that, The polyol is selected from at least one of polyether polyols, polyester polyols, and polycarbonate polyols; The inorganic flame-retardant filler is selected from at least one of magnesium hydroxide and aluminum hydroxide; The flame retardant is selected from at least one of dimethyl methylphosphonate, tri(1-chloro-2-propyl) phosphate, and triethyl phosphate; The catalyst is selected from at least one of organotin catalysts and tertiary amine catalysts; The foaming agent is selected from at least one of water, cyclopentane, and fluorinated hydrocarbons; The polyisocyanate is selected from at least one of polydiphenylmethane diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

5. A method for preparing a composite fire-retardant material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step (1): After pretreatment of the alumina fiber mesh, it is immersed in the chemical copper plating solution to carry out an autocatalytic reduction reaction, and a metallic copper plating layer is deposited on the surface of the alumina fiber. After cleaning and drying, the alumina fiber reinforced material is obtained. Step (2): After dehydrating the polyol, it is mixed evenly with flame retardant, catalyst, foaming agent, expandable graphite, ammonium polyphosphate and inorganic flame retardant filler to obtain premix. Step (3): The alumina fiber reinforced material obtained in step (1) is laid in a molding mold in a parallel in-plane direction. The premixed material obtained in step (2) is mixed with polyisocyanate and then injected into the molding mold with the reinforced material. The mixture foams, expands and wraps the reinforced material in the mold. After heat preservation and curing, the composite fireproof material is obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the pretreatment includes heat treatment, alkaline washing, sensitization and activation in sequence; The heat treatment conditions are: treatment at 350℃~450℃ for 0.5h~2h; The alkaline washing conditions are: treatment with a 15.0 mol / L to 25.0 mol / L potassium hydroxide aqueous solution at a temperature of 40℃ to 60℃ for 10 min to 20 min; The sensitization conditions are: treatment with a 0.2 mol / L to 0.8 mol / L stannous chloride aqueous solution at a temperature of 20℃ to 30℃ for 10 min to 20 min; The activation conditions are: treatment with a 0.5 mol / L to 1.5 mol / L silver nitrate aqueous solution at a temperature of 20 to 30°C for 5 to 15 minutes.

7. The preparation method according to claim 5, characterized in that, In step (1), the electroless copper plating solution contains the following components by mass percentage: 1.0%~2.0% inorganic copper salt, 3.0%~5.0% complexing agent, 2.0%~4.0% reducing agent, and the balance is water; The conditions for the autocatalytic reduction reaction are: reaction at a constant temperature of 50℃~70℃ for 5min~20min; The drying conditions are as follows: drying under vacuum at a temperature of 70℃~90℃ for 5~20 minutes.

8. The preparation method according to claim 5, characterized in that, In step (2), the dehydration treatment conditions are: vacuum distillation for 1.5h to 3h at 110℃~130℃ and a vacuum degree of -0.08MPa~-0.12MPa; The mixing conditions are: stirring at a speed of 300 r / min to 800 r / min for 20 min to 40 min.

9. The preparation method according to claim 5, characterized in that, In step (3), the mixing time between the premix and the polyisocyanate is 30s to 90s; The conditions for heat preservation and curing are: heat preservation at a temperature of 40℃~50℃ for 12h~36h.

10. The application of a composite fire-resistant material as described in any one of claims 1 to 4 in the preparation of cable trench firewalls, battery pack thermal management gaskets, or spacecraft thermal protection systems.

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