Special flame-retardant polyurethane composite material for new energy automobile and preparation method of special flame-retardant polyurethane composite material

Abstract

According to the special flame-retardant polyurethane composite material for the new energy automobile and the preparation method of the special flame-retardant polyurethane composite material, due to the introduction of the composite flame retardant in the formula, especially the synergistic effect of the phosphorus-based flame retardant, the nitrogen-based flame retardant and the inorganic nano flame-retardant particles, the flame-retardant property of the material is greatly improved, and by calculating the flame-retardant synergistic coefficient, the flame-retardant property of the material is greatly improved. According to the flame-retardant polyurethane composite material and the preparation method thereof, the flame-retardant value of the flame-retardant polyurethane composite material is ensured to be greater than or equal to 0.85, the flame-retardant effect of the composite material can reach a preset standard, the modified polyol resin and the isocyanate are used as main components of the polyurethane composite material, good mechanical properties and structural stability are provided, and the mechanical properties and heat resistance of the material are further enhanced by adding the nano synergist; according to the present invention, the material can be maintained stable under the high temperature or fire hazard condition so as to reduce the fire hazard accident occurrence, such that the energy source and the loss can be reduced, the catalyst and the additive in the formula can easily improve the processing performance of the material so as to easily perform injection molding, extrusion or compression molding, such that the production cost can be easily reduced, and the production efficiency can be easily improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle materials, and in particular to a flame-retardant polyurethane composite material special for new energy vehicles and a preparation method thereof. Background Art

[0002] With the rapid development of the new energy vehicle industry, the safety and environmental protection requirements for automotive interior materials are increasing. As one of the important materials for the interior of new energy vehicles, the flame retardant performance of flame-retardant polyurethane composite materials directly affects the safety of the vehicle. Although traditional polyurethane composite materials have certain flame retardant properties, their flame retardant effect is often unsatisfactory under high temperature or fire conditions, and it is difficult to meet the high flame retardant performance requirements of new energy vehicles.

[0003] In order to improve the flame retardant properties of polyurethane composites, researchers began to explore methods of adding flame retardants. However, simply adding flame retardants often leads to a decrease in the mechanical properties of the composites, and also affects their processing performance and service life. Therefore, how to improve the flame retardant properties of the composites while ensuring their mechanical properties has become a problem that needs to be solved urgently. Summary of the Invention

[0004] In view of this, the present invention proposes a flame-retardant polyurethane composite material specially designed for new energy vehicles and a preparation method thereof, which can effectively ensure the mechanical properties of the composite material while improving its flame retardant properties.

[0005] The technical solution of the present invention is achieved as follows:

[0006] A flame-retardant polyurethane composite material specially designed for new energy vehicles, comprising:

[0007] 40-60 parts of modified polyol resin;

[0008] 20-35 parts of isocyanate;

[0009] 15-25 parts of composite flame retardant;

[0010] 2-8 parts of nano synergist;

[0011] 0.1-1.5 parts of catalyst;

[0012] 0.5-3 parts of additives;

[0013] The composite flame retardant is composed of phosphorus-based flame retardant, nitrogen-based flame retardant and inorganic nano flame retardant particles in the following proportions:

[0014] F e =(P%×N%) / LOI 2 ;

[0015] Among them, the F eis the flame retardant synergy coefficient, and F e ≥0.85, where P is the mass percentage of phosphorus, N is the mass percentage of nitrogen, and LOI is the limiting oxygen index.

[0016] As a further optional solution for the flame-retardant polyurethane composite material for new energy vehicles, the modified polyol resin is a copolymer of vegetable oil-based polyol and polyether polyol, has a hydroxyl value range of 200-400 mgKOH / g, and contains 0.5-2 wt% of siloxane side chains.

[0017] As a further optional solution for the flame-retardant polyurethane composite material for new energy vehicles, the isocyanate is one or more of diphenylmethane diisocyanate, toluene diisocyanate or polymethylene polyisocyanate.

[0018] As a further optional solution for the flame-retardant polyurethane composite material for new energy vehicles, the nano synergist is surface hydroxylated graphene or silicon dioxide nanosheets with a particle size of ≤50 nm.

[0019] A method for preparing a flame-retardant polyurethane composite material for new energy vehicles, specifically comprising:

[0020] Step S1, mixing the modified polyol resin, the composite flame retardant and the nano synergist under vacuum conditions, controlling the moisture content to ≤0.05% and the temperature to 80-100° C.;

[0021] Step S2, adding isocyanate dropwise to the product of step S1, adding a catalyst and reacting at 120-140° C. for 2-4 hours until the NCO content is ≤0.5%;

[0022] Step S3, adding additives to the product of step S2, and subjecting the product to injection molding or compression molding, with a holding pressure of 10-15 MPa and a holding time of 10-30 minutes;

[0023] Step S4, post-treatment: heat treatment by gradient heating to 160-180°C for 4-8 hours to form a cross-linking density ≥ 0.8 mol / cm 3 mesh structure.

[0024] As a further optional solution to the method for preparing the flame-retardant polyurethane composite material for new energy vehicles, the additives in step S3 include 0.3-1.5wt% of carbon nanotube dispersion and 0.1-0.5wt% of ultraviolet absorber, and the composite material needs to be ultrasonically shaken for 10-20 minutes before molding.

[0025] A flame-retardant polyurethane composite material preparation device for new energy vehicles, comprising:

[0026] A mixing device is used to mix the modified polyol resin, composite flame retardant and nano synergist under vacuum conditions, and control the moisture content to ≤0.05% and maintain the temperature at 80-100°C;

[0027] Reactor: connected to the mixing device, used to receive the product of the mixing device and dropwise add isocyanate thereto. The reactor is equipped with a heating system and a stirrer to react at a temperature of 120-140°C for 2-4 hours until the NCO content is ≤0.5%;

[0028] Molding equipment: connected to the reactor, used to receive the product from the reactor and add additives to it;

[0029] Heat treatment device: connected to the molding equipment, used for post-processing of the molded composite products.

[0030] As a further optional solution for the equipment for preparing flame-retardant polyurethane composite materials for new energy vehicles, the reactor is further equipped with an NCO content detection device for real-time monitoring of the reaction progress.

[0031] As a further optional solution for the preparation equipment of flame-retardant polyurethane composite materials for new energy vehicles, the heat treatment device includes a heating system and a temperature control system, which is used to increase the temperature to 160-180°C according to a set gradient and maintain the heat treatment time for 4-8 hours to form a cross-linking density ≥ 0.8 mol / cm 3 mesh structure.

[0032] The beneficial effects of the present invention are as follows: the introduction of the composite flame retardant in the formula, in particular the synergistic effect of the phosphorus-based flame retardant, the nitrogen-based flame retardant and the inorganic nano flame retardant particles, greatly improves the flame retardant properties of the material; by calculating the flame retardant synergy coefficient and ensuring that its value is greater than or equal to 0.85, it can be ensured that the flame retardant effect of the composite material meets the predetermined standard; the modified polyol resin and isocyanate, as the main components of the polyurethane composite material, provide good mechanical properties and structural stability; the addition of the nano synergist further enhances the mechanical properties and heat resistance of the material, allowing it to remain stable under high temperature or fire conditions; the composite material uses an environmentally friendly flame retardant, reducing pollution to the environment; at the same time, due to its excellent flame retardant properties, it can reduce the occurrence of fire accidents, thereby saving energy and reducing losses; the catalyst and additives in the formula help improve the processing properties of the material, making it easy to be injection molded, extruded or compression molded, which is conducive to reducing production costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a formula table of a flame-retardant polyurethane composite material specially used for new energy vehicles of the present invention;

[0035] Figure 2 This is a schematic flow chart of a method for preparing a flame-retardant polyurethane composite material for new energy vehicles according to the present invention;

[0036] Figure 3 This is a schematic diagram of the composition of a flame-retardant polyurethane composite material preparation device for new energy vehicles according to the present invention. DETAILED DESCRIPTION

[0037] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] refer to Figures 1 to 3 , a flame-retardant polyurethane composite material for new energy vehicles, comprising:

[0039] 40-60 parts of modified polyol resin;

[0040] 20-35 parts of isocyanate;

[0041] 15-25 parts of composite flame retardant;

[0042] 2-8 parts of nano synergist;

[0043] 0.1-1.5 parts of catalyst;

[0044] 0.5-3 parts of additives;

[0045] The composite flame retardant is composed of phosphorus-based flame retardant, nitrogen-based flame retardant and inorganic nano flame retardant particles in the following proportions:

[0046] F e =(P%×N%) / LOI 2 ;

[0047] Among them, the F e is the flame retardant synergy coefficient, and F e≥0.85, where P is the mass percentage of phosphorus, N is the mass percentage of nitrogen, and LOI is the limiting oxygen index.

[0048] In this embodiment, the introduction of composite flame retardants in the formulation, particularly the synergistic effect of phosphorus-based flame retardants, nitrogen-based flame retardants, and inorganic nano-flame retardant particles, greatly improves the flame retardant properties of the material. By calculating the flame retardant synergy coefficient and ensuring its value is greater than or equal to 0.85, it is possible to ensure that the flame retardant effect of the composite material meets the predetermined standard. The modified polyol resin and isocyanate, as the main components of the polyurethane composite material, provide excellent mechanical properties and structural stability. The addition of the nano-synergist further enhances the mechanical properties and heat resistance of the material, allowing it to remain stable under high temperature or fire conditions. The composite material uses environmentally friendly flame retardants, reducing environmental pollution. At the same time, due to its excellent flame retardant properties, it can reduce the occurrence of fire accidents, thereby saving energy and reducing losses. The catalysts and additives in the formulation help improve the processing properties of the material, making it easy to injection mold, extrusion, or compression mold, which helps reduce production costs and improve production efficiency.

[0049] Preferably, the modified polyol resin is a copolymer of vegetable oil-based polyol and polyether polyol, has a hydroxyl value in the range of 200-400 mgKOH / g, and contains 0.5-2 wt% of siloxane side chains.

[0050] In this embodiment, the introduction of vegetable oil-based polyols makes the composite material have the characteristics of renewable resources, reducing the dependence on non-renewable resources such as petroleum. The addition of siloxane side chains not only improves the performance of the material, but also usually comes from an environmentally friendly synthesis path, further enhancing the environmental friendliness of the composite material. The copolymerization of vegetable oil-based polyols and polyether polyols produces new chemical structures. These structures help to interact with flame retardants, thereby improving the overall flame retardant effect. The siloxane side chains may form a protective layer at high temperatures, slowing down the transfer of heat and the penetration of oxygen, further enhancing the flame retardant performance. The specific hydroxyl value range (200-400mgKOH / g) ensures the good compatibility of the polyol resin with the isocyanate. The activity of the cyanate reaction is moderate, which helps to form a stable cross-linked structure, thereby improving the mechanical properties of the composite material. The introduction of siloxane side chains can enhance the flexibility and toughness of the molecular chain, so that the composite material has better resistance to deformation and fracture when subjected to external forces. The siloxane side chain has excellent heat resistance and chemical corrosion resistance. Its introduction can improve the heat resistance and aging resistance of the composite material. The copolymer of vegetable oil-based polyols and polyether polyols usually has good fluidity, which is conducive to the processing and molding of the composite material. The addition of siloxane side chains may further improve the processing performance of the material, such as reducing viscosity, increasing melt fluidity, etc., making the composite material easier to injection molding, extrusion or compression molding.

[0051] Preferably, the isocyanate is one or more of diphenylmethane diisocyanate, toluene diisocyanate or polymethylene polyisocyanate.

[0052] In this embodiment, the isocyanate is selected as one or more of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI) or polymethylene polyisocyanate (PMDI). The polyurethane generated by the reaction of these with polyols has excellent mechanical properties such as high strength, high toughness and wear resistance. These properties enable the composite material to withstand large external forces and impacts and is not prone to deformation and cracking. The type of isocyanate has an important influence on the flame retardant properties of the polyurethane composite material. MDI, TDI and PMD I can all improve the flame retardancy of the material to a certain extent. Through reasonable formulation design, the self-extinguishing or flame retardant properties of the composite material can be achieved, thereby reducing the risk of fire. The polyurethane composite material prepared by MDI, TDI and PMD I can still remain stable at high temperatures and is not prone to thermal decomposition and degradation. At the same time, they also have good weather resistance and can resist the damage to the material properties caused by environmental factors such as ultraviolet rays and oxidation. By adjusting the ratio and type of MDI, TDI and PMD I, polyurethane composite materials with different properties can be customized. For example, the proportion of MDI can be increased to improve the strength and hardness of the material, or the proportion of TDI can be increased to improve the strength and hardness of the material. I ratio to improve the flexibility and elasticity of the material. This customizability allows the performance of the composite material to be optimized according to different application requirements.

[0053] Preferably, the nanosynergist is surface hydroxylated graphene or silica nanosheets with a particle size of ≤50 nm.

[0054] In this embodiment, the surface hydroxylated graphene and silica nanosheets act as nanosynergists, which can synergize with the flame retardant to enhance the flame retardancy of the composite material. The lamellar structure and excellent barrier properties of graphene, as well as the heat absorption capacity and high specific surface area of silica, work together in the combustion process to effectively slow down the spread of flames and reduce the release of combustion heat. The addition of nanosynergists can significantly reduce the combustion rate of the composite material, prolong the burning time, and provide more time for escape and rescue. During the combustion process, the nanosynergists can form a protective layer on the surface of the composite material to isolate oxygen and heat, further step to slow down the combustion process; the surface hydroxylation treatment makes the graphene and silica nanosheets have good dispersion in the composite material, avoids the occurrence of agglomeration, and is beneficial to the uniformity and stability of the composite material; the addition of nanosynergists can reduce the viscosity of the composite material to a certain extent, improve the fluidity, and facilitate the processing of molding and injection molding; both graphene and silica nanosheets have high thermal stability and can maintain the stable performance of the composite material at high temperatures. The addition of nanosynergists can also enhance the weather resistance of the composite material and resist the damage to the material performance caused by environmental factors such as ultraviolet rays and oxidation.

[0055] A method for preparing a flame-retardant polyurethane composite material for new energy vehicles, specifically comprising:

[0056] Step S1, mixing the modified polyol resin, the composite flame retardant and the nano synergist under vacuum conditions, controlling the moisture content to ≤0.05% and the temperature to 80-100° C.;

[0057] Step S2, adding isocyanate dropwise to the product of step S1, adding a catalyst and reacting at 120-140° C. for 2-4 hours until the NCO content is ≤0.5%;

[0058] Step S3, adding additives to the product of step S2, and subjecting the product to injection molding or compression molding, with a holding pressure of 10-15 MPa and a holding time of 10-30 minutes;

[0059] Step S4, post-treatment: heat treatment by gradient heating to 160-180°C for 4-8 hours to form a cross-linking density ≥ 0.8 mol / cm 3 mesh structure.

[0060] In this embodiment, by mixing the modified polyol resin, composite flame retardant and nanosynergist under vacuum conditions and strictly controlling the moisture content and temperature, the uniform distribution and effective effect of the flame retardant component in the material are ensured, which helps to form an efficient flame retardant system and significantly improves the flame retardant properties of the composite material; the reaction of the modified polyol resin and isocyanate generates a high-strength polyurethane network structure, and the addition of the nanosynergist further enhances the mechanical properties of the material, which makes the composite material have excellent tensile, compression and shear resistance, meeting the material strength requirements of new energy vehicles; the gradient temperature increase heat treatment during the preparation process promotes further crosslinking and curing of the polyurethane chain segments, forming a network structure with a high crosslinking density, which helps The invention is used to improve the heat resistance and weather resistance of the composite material, so that it can maintain stable performance under high temperature or harsh environment; in step S1, the raw materials are mixed under vacuum conditions to effectively remove moisture and air in the material, avoid the generation of bubbles and defects, and ensure the uniformity and density of the composite material; by precisely controlling the temperature and time and adding a catalyst, the full reaction of the isocyanate and the polyol resin is ensured, the NCO content is reduced, and the stability and reliability of the material are improved; in step S3, the injection molding or compression molding technology is used, combined with appropriate holding pressure and holding time, to achieve rapid molding and curing of the composite material, and the gradient temperature rising heat treatment in step S4 further promotes the crosslinking and curing of the material, thereby improving production efficiency.

[0061] Preferably, the additives in step S3 include 0.3-1.5 wt% of carbon nanotube dispersion and 0.1-0.5 wt% of ultraviolet absorber, and the product needs to be ultrasonically shaken for 10-20 minutes before molding.

[0062] In this embodiment, carbon nanotubes have excellent mechanical properties and toughness. Adding them to the composite material as a dispersion can significantly improve the strength and toughness of the material. The carbon nanotubes form a network structure in the material, effectively dispersing and bearing external forces, thereby improving the overall mechanical properties of the composite material. The addition of carbon nanotubes can also improve the wear resistance and fatigue resistance of the composite material. Under friction and fatigue loads, carbon nanotubes can act as a reinforcing phase to slow down the wear and fatigue damage of the material and extend its service life. Carbon nanotubes have good electrical conductivity. Their addition makes the composite material have a certain conductivity, which is helpful for components such as the battery pack shell in new energy vehicles to achieve functions such as heat dissipation and electromagnetic shielding of the battery pack, thereby improving the safety and reliability of the battery system. ; The addition of UV absorbers can effectively absorb and convert UV radiation, reducing the aging, fading and performance degradation of materials caused by UV exposure, which is especially important for new energy vehicle components exposed to outdoor environments for a long time; UV absorbers protect polymers from photochemical decomposition by selectively absorbing high-energy UV rays and converting energy into heat or harmless low-energy radiation, which helps maintain the long-term stability and performance of composite materials; ultrasonic vibration treatment of the composite material for 10-20 minutes before molding helps to evenly disperse carbon nanotubes and UV absorbers in the material. The vibration of ultrasound can break up agglomerates, promote the full mixing of additives and matrix resin, and improve the uniformity and performance of the composite material.

[0063] A flame-retardant polyurethane composite material preparation device for new energy vehicles, comprising:

[0064] A mixing device is used to mix the modified polyol resin, composite flame retardant and nano synergist under vacuum conditions, and control the moisture content to ≤0.05% and maintain the temperature at 80-100°C;

[0065] Reactor: connected to the mixing device, used to receive the product of the mixing device and dropwise add isocyanate thereto. The reactor is equipped with a heating system and a stirrer to react at a temperature of 120-140°C for 2-4 hours until the NCO content is ≤0.5%;

[0066] Molding equipment: connected to the reactor, used to receive the product from the reactor and add additives to it;

[0067] Heat treatment device: connected to the molding equipment, used for post-processing of the molded composite products.

[0068] In this embodiment, the mixing device mixes the modified polyol resin, the composite flame retardant and the nano synergist under vacuum conditions, which can effectively remove air and moisture from the mixture, prevent the generation of bubbles in the subsequent reaction process, and affect the performance of the material. The moisture content is controlled at ≤0.05%, which can avoid the reaction of moisture with isocyanate at high temperature to form urea bonds, thereby affecting the crosslinking degree and performance of the polyurethane composite material. The temperature of the mixture is maintained at 80-100°C, which can ensure that the various raw materials do not react prematurely during the mixing process and is conducive to the uniform dispersion of the raw materials. The reactor is equipped with a heating system and an agitator, which can react at a temperature of 120-140°C for 2-4 hours to ensure that the raw materials are fully reacted to form a high molecular weight polyurethane composite material. The function of the agitator is to ensure the reaction The materials are evenly mixed to improve the reaction efficiency. By controlling the reaction time and temperature, the NCO (isocyanate group) content is ensured to be ≤0.5%, which is conducive to obtaining a polyurethane composite material with a moderate degree of crosslinking and stable performance. Adding additives such as catalysts and foaming agents to the molding equipment can further adjust the performance of the polyurethane composite material, such as increasing the reaction rate and improving the pore structure. The molding equipment can adjust the molding process parameters such as temperature, pressure, time, etc. according to different product requirements to meet the production requirements of products of different shapes and sizes. Heat treatment of the molded composite product can further solidify the material and improve the mechanical properties and heat resistance of the material. Heat treatment can also eliminate the internal stress generated by the material during the molding process and improve the dimensional stability and service life of the material.

[0069] Preferably, the reactor is further equipped with an NCO content detection device for real-time monitoring of the reaction progress.

[0070] In this embodiment, the NCO content detection device can monitor the NCO (isocyanate group) content in the reactor in real time, thereby accurately monitoring the reaction progress. This avoids performance fluctuations caused by inaccurate reaction time in traditional methods and improves product stability and consistency. By real-time monitoring of the NCO content, reaction conditions such as temperature and stirring speed can be adjusted in a timely manner to ensure that the reaction proceeds under optimal conditions, which helps to reduce the occurrence of side reactions and improve the utilization rate of raw materials and the purity of the product. Real-time monitoring of the NCO content helps to accurately determine the reaction endpoint, thereby avoiding unnecessary waste of reaction time, which can significantly shorten the production cycle and improve production efficiency. By accurately controlling the reaction process, unnecessary energy consumption can be reduced. For example, when the reaction approaches the endpoint, the power of the heating system can be appropriately reduced to save energy. Real-time monitoring of the NCO content helps to ensure that the product meets the predetermined performance indicators. When the NCO content drops to ≤0.5%, it indicates that the reaction has been fully progressed and the product performance is stable and reliable. By accurately controlling the reaction process, the scrap rate caused by incomplete or overreaction can be reduced, which helps to reduce production costs and improve economic benefits.

[0071] Preferably, the heat treatment device includes a heating system and a temperature control system, which is used to raise the temperature to 160-180°C according to a set gradient and maintain the heat treatment time for 4-8 hours to form a crosslinking density ≥ 0.8 mol / cm 3 mesh structure.

[0072] In this embodiment, through gradient heating and long-term heat treatment, the cross-linking reaction between the polyurethane molecular chains is fully carried out, thereby forming a network structure with high cross-linking density. The increase in cross-linking density helps to enhance the mechanical properties and heat resistance of the material. Long-term heat treatment can also make the network structure more stable, reduce structural changes caused by temperature changes, and improve the dimensional stability and service life of the material; the network structure with high cross-linking density makes the polyurethane composite material have higher tensile strength, compressive strength and bending strength, meeting the high requirements of new energy vehicles for the mechanical properties of materials. The stable network structure formed during the heat treatment process helps to improve the heat resistance of the material, so that the composite material can be used in high temperature environments. Maintain stable performance under the environment. Heat treatment can also improve the chemical resistance of polyurethane composite materials and enhance their resistance to acids, alkalis and other chemicals; the gradient heating method can avoid excessive internal stress of the material caused by rapid heating, which is conducive to uniform heating of the material and stable performance. The temperature control system can accurately control the temperature during the heat treatment process to ensure that the material is heat treated within the set temperature range, thereby improving the quality and consistency of the product; the heat treatment device is equipped with an automatic control system, which can realize the automation and intelligence of the heat treatment process, reduce manual intervention, and improve production efficiency. By accurately controlling the heat treatment time and temperature, the production cycle can be shortened and the delivery speed of the product can be increased.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flame-retardant polyurethane composite material for new energy vehicles, characterized in that: include: 40-60 parts of modified polyol resin; 20-35 parts of isocyanate; 15-25 parts of composite flame retardant; 2-8 parts of nano synergist; 0.1-1.5 parts of catalyst; 0.5-3 parts of additives; The composite flame retardant is composed of phosphorus-based flame retardant, nitrogen-based flame retardant and inorganic nano flame retardant particles in the following proportions: F e =(P%×N%) / LAW 2 ; Among them, the F e is the flame retardant synergy coefficient, and F e ≥0.85, where P is the mass percentage of phosphorus, N is the mass percentage of nitrogen, and LOI is the limiting oxygen index.

2. The flame-retardant polyurethane composite material for new energy vehicles according to claim 1, characterized in that: The modified polyol resin is a copolymer of vegetable oil-based polyol and polyether polyol, has a hydroxyl value ranging from 200 to 400 mgKOH / g, and contains 0.5 to 2 wt% of siloxane side chains.

3. The flame-retardant polyurethane composite material for new energy vehicles according to claim 2, characterized in that: The isocyanate is one or more of diphenylmethane diisocyanate, toluene diisocyanate or polymethylene polyisocyanate.

4. The flame-retardant polyurethane composite material for new energy vehicles according to claim 3, characterized in that: The nano synergist is a graphene or silicon dioxide nanosheet with a surface hydroxylation and a particle size of ≤50nm.

5. A method for preparing a flame-retardant polyurethane composite material for new energy vehicles, characterized in that: Specifically include: Step S1, mixing the modified polyol resin, the composite flame retardant and the nano synergist under vacuum conditions, controlling the moisture content to ≤0.05% and the temperature to 80-100° C.; Step S2, adding isocyanate dropwise to the product of step S1, adding a catalyst and reacting at 120-140° C. for 2-4 hours until the NCO content is ≤0.5%; Step S3, adding additives to the product of step S2, and subjecting the product to injection molding or compression molding, with a holding pressure of 10-15 MPa and a holding time of 10-30 minutes; Step S4, post-treatment: heat treatment by gradient heating to 160-180°C for 4-8 hours to form a cross-linking density ≥ 0.8 mol / cm 3 mesh structure.

6. The method for preparing a flame-retardant polyurethane composite material for new energy vehicles according to claim 5, characterized in that: The additives in step S3 include 0.3-1.5 wt% of carbon nanotube dispersion and 0.1-0.5 wt% of ultraviolet absorber, and the product needs to be ultrasonically shaken for 10-20 minutes before molding.

7. A flame-retardant polyurethane composite material preparation device for new energy vehicles, characterized in that: include: A mixing device is used to mix the modified polyol resin, composite flame retardant and nano synergist under vacuum conditions, and control the moisture content to ≤ 0.05% and maintain the temperature at 80-100°C; Reactor: connected to the mixing device, used to receive the product of the mixing device and dropwise add isocyanate thereto. The reactor is equipped with a heating system and a stirrer to react at a temperature of 120-140°C for 2-4 hours until the NCO content is ≤0.5%; Molding equipment: connected to the reactor, used to receive the product from the reactor and add additives to it; Heat treatment device: connected to the molding equipment, used for post-processing of the molded composite products.

8. The flame-retardant polyurethane composite material preparation equipment for new energy vehicles according to claim 7, characterized in that: The reactor is also equipped with an NCO content detection device for real-time monitoring of the reaction process.

9. The flame-retardant polyurethane composite material preparation equipment for new energy vehicles according to claim 8, characterized in that: The heat treatment device includes a heating system and a temperature control system, which is used to increase the temperature to 160-180°C according to a set gradient and maintain the heat treatment time for 4-8 hours to form a crosslinking density ≥ 0.8 mol / cm 3 mesh structure.

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