Polyurethane flame-retardant material, preparation method thereof and new energy automobile charging port cover

Abstract

The invention discloses a polyurethane flame-retardant material, a preparation method thereof and a new energy automobile charging port cover, the polyurethane flame-retardant material comprises thermoplastic polyurethane resin, a hydrogenated styrene-butadiene block copolymer, a maleic anhydride grafted hydrogenated styrene-butadiene block copolymer, polyphenyl ether and a flame retardant, the flame retardant comprises a silane modified phosphorus flame retardant and a silane modified nitrogen flame retardant; the preparation method comprises the following steps: mixing and extruding the hydrogenated styrene-butadiene block copolymer, the maleic anhydride grafted hydrogenated styrene-butadiene block copolymer and the polyphenyl ether to prepare master batch; mixing and extruding the master batch, the thermoplastic polyurethane resin and the flame retardant; the polyurethane flame-retardant material prepared by the invention can meet the requirement of the charging port cover of the electric vehicle on a high-flame-retardant polyurethane elastomer material, the flame retardance reaches the V0 level in the UL94 standard, and the polyurethane flame-retardant material does not crack or separate out after being placed in water at 80 DEG C for 168 hours.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and more particularly to materials used in charging port covers for new energy vehicles, specifically to a polyurethane flame-retardant material, its preparation method, and a charging port cover for new energy vehicles. Background Technology

[0002] Charging port covers for new energy vehicles need to maintain high sealing performance and structural stability over long periods of time in complex environments. Currently, mainstream materials such as reinforced PC and ABS engineering plastics have defects such as high hardness, poor elasticity, low-temperature embrittlement, easy aging, and poor flame retardancy, while metal materials are heavy and have poor insulation. While traditional polyurethane materials offer advantages in elasticity, they suffer from poor flame retardancy. The high temperatures generated during TPU combustion far exceed its melting point, causing the material to rapidly melt into a low-viscosity liquid. This also triggers thermal and oxidative degradation of its polymer chains, producing smaller molecular fragments (oligomers, monomers, flammable gases, etc.). These fragments further reduce the viscosity and molecular weight of the melt, making it more fluid and prone to dripping. Furthermore, it is difficult to form an effective char layer to prevent this molten material from dripping under gravity during combustion, which can easily ignite a fire. Simultaneously, many highly effective flame retardants (especially additive flame retardants such as phosphorus-based, halogen-based, and inorganic flame retardants) have limited compatibility with the TPU matrix. TPU is a multiphase polymer composed of hard and soft segments; flame retardant molecules may dissolve more easily in the soft or hard segments, or neither may dissolve readily. When compatibility is poor, flame retardant molecules gradually migrate from the polymer matrix to the surface during post-processing cooling or long-term storage / use, causing irreversible damage to the product's performance and appearance. Summary of the Invention

[0003] The purpose of this invention is to overcome one or more shortcomings of the prior art and provide an improved polyurethane flame retardant material that can combine good elasticity, water resistance, and flame retardancy, while also solving problems such as polyurethane's tendency to generate molten droplets at high temperatures and the easy precipitation of flame retardant molecules.

[0004] This invention also provides a method for preparing polyurethane flame-retardant material and its application in the preparation of charging port covers for new energy vehicles.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A polyurethane flame retardant material comprising a thermoplastic polyurethane resin and a flame retardant, wherein the polyurethane flame retardant material further comprises a hydrogenated styrene-butadiene block copolymer, a maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer and polyphenylene ether, and wherein the flame retardant comprises a silane-modified phosphorus-based flame retardant and a silane-modified nitrogen-based flame retardant.

[0007] The mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 5-25:0.3-3.0:0.2-2:1.

[0008] The mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.15-0.45:0.1-0.4.

[0009] In some embodiments of the present invention, the mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 6-23.5:0.35-2.8:0.25-2:1. Further, the mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 8-15:0.5-1.5:0.4-1.2:1.

[0010] According to some specific aspects of the present invention, the mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 10-12∶0.8-1.2∶0.6-1.0∶1.

[0011] In some embodiments of the present invention, the mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.17-0.4:0.1-0.35; further, the mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.25-0.38:0.15-0.25.

[0012] According to some specific aspects of the present invention, the mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.28-0.35:0.18-0.25.

[0013] In some embodiments of the present invention, the polyurethane flame retardant material comprises, by weight parts: 50-70 parts of thermoplastic polyurethane resin, 3-8 parts of hydrogenated styrene-butadiene block copolymer, 2-6 parts of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 3-8 parts of polyphenylene ether, 12-20 parts of silane-modified phosphorus flame retardant, 8-16 parts of silane-modified nitrogen flame retardant, and 0.2-1.0 parts of antioxidant.

[0014] In some embodiments of the present invention, the content of the thermoplastic polyurethane resin in the polyurethane flame retardant material is more than 50% by mass percentage.

[0015] Furthermore, by mass percentage, the content of the thermoplastic polyurethane resin in the polyurethane flame retardant material is 50%-70%.

[0016] According to some specific aspects of the present invention, the antioxidant may include, but is not limited to, antioxidant 1010, antioxidant 1098, antioxidant 1024, etc.

[0017] According to the present invention, the silane-modified phosphorus flame retardant is prepared by reacting a silane coupling agent with a phosphorus flame retardant, and the silane-modified nitrogen flame retardant is prepared by reacting a silane coupling agent with a nitrogen flame retardant.

[0018] In some embodiments of the present invention, the silane coupling agent is γ-aminopropyltriethoxysilane and / or γ-methacryloyloxypropyltrimethoxysilane.

[0019] In some embodiments of the present invention, during the preparation of the silane-modified phosphorus flame retardant, the mass ratio of silane coupling agent to phosphorus flame retardant is 1-5:100.

[0020] In some embodiments of the present invention, during the preparation of the silane-modified nitrogen-based flame retardant, the mass ratio of silane coupling agent to nitrogen-based flame retardant is 3-8:100.

[0021] In some embodiments of the present invention, the phosphorus-based flame retardant is a hypophosphite (e.g., aluminum hypophosphite, magnesium hypophosphite, etc.).

[0022] In some embodiments of the present invention, the phosphorus-based flame retardant is melamine cyanurate (MCA) or the like.

[0023] In some embodiments of the present invention, the mass ratio of the silane-modified phosphorus flame retardant to the silane-modified nitrogen flame retardant is 1-3:1.

[0024] According to some specific aspects of the present invention, the preparation method of the silane-modified phosphorus-based flame retardant includes:

[0025] The phosphorus-based flame retardant is pre-dried in a vacuum drying oven to remove adsorbed moisture. Generally, it is difficult to completely remove moisture; the moisture content after drying is approximately 0.05%-0.2% (this ensures uniform dispersion and facilitates subsequent hydrolysis). After drying, the mixture is sieved to ensure uniform particle dispersion. The dried phosphorus-based flame retardant is then added to anhydrous ethanol (generally with a moisture content of approximately 0.2%) and treated using an ultrasonic disperser in a water bath at 40-60℃ to form a uniform suspension.

[0026] Weigh the silane coupling agent according to the specified ratio, and slowly add it dropwise to the suspension while mechanically stirring. After the addition is complete, raise the temperature to 50-70℃ and initiate the reaction. A protective gas (such as nitrogen or argon) should be introduced throughout the reaction to isolate oxygen. Stirring should be maintained during the reaction to ensure complete hydrolysis of the silane and its reaction with the surface hydroxyl groups of the phosphorus-based flame retardant. After the reaction is complete, the mixture should be vacuum filtered, and the solid product collected. Wash with anhydrous ethanol and dry to obtain the silane-modified phosphorus-based flame retardant.

[0027] Furthermore, the solid-liquid ratio of phosphorus-based flame retardant to anhydrous ethanol is 1:5 to 1:10 (g / mL, the ratio of the mass of phosphorus-based flame retardant to the volume of anhydrous ethanol).

[0028] According to some specific aspects of the present invention, the preparation method of the silane-modified nitrogen-based flame retardant includes:

[0029] Melamine cyanurate (MCA) was pre-dried in a vacuum drying oven to remove adsorbed moisture, resulting in a moisture content of approximately 0.05%-0.2%. The dried MCA was then added to toluene and treated with an ultrasonic disperser to ensure uniform dispersion of the MCA in the toluene, forming a stable suspension.

[0030] Weigh the silane coupling agent according to the mass ratio, and slowly add the silane coupling agent dropwise to the suspension while mechanically stirring. After the addition is complete, a protective gas (such as nitrogen or argon) is introduced throughout the process to isolate oxygen. Continue ultrasonic treatment to promote the hydrolysis of the silane coupling agent and its grafting onto the MCA surface. After the reaction is complete, the mixture is vacuum filtered, and the solid product is collected. Wash with anhydrous toluene and dry to obtain the silane-modified nitrogen-based flame retardant.

[0031] Furthermore, the solid-liquid ratio of MCA to toluene solution is 1:8 to 1:12 (g / mL).

[0032] According to some preferred aspects of the present invention, the thermoplastic polyurethane resin has a Shore hardness of 80A-95A (e.g., 80A, 81A, 82A, 83A, 84A, 85A, 86A, 87A, 88A, 89A, 90A, 91A, 92A, 93A, 94A, etc.) and a melt index of 2-30 g / 10min (e.g., 2 g / 10min, 3 g / 10min, 4 g / 10min, 5 g / 10min, 6 g / 10min) measured at 190°C and 2.16 kg. 7g / 10min, 8g / 10min, 9g / 10min, 10g / 10min, 12g / 10min, 13g / 10min, 15g / 10min, 16g / 10min, 18g / 10min, 20g / 10m in, 21g / 10min, 22g / 10min, 23g / 10min, 24g / 10min, 25g / 10min, 26g / 10min, 27g / 10min, 28g / 10min, 29g / 10min, etc.).

[0033] According to some preferred aspects of the invention, the styrene content in the hydrogenated styrene-butadiene block copolymer is 25%-60% (e.g., it can be 25%, 26%, 27%, 28%, 29%, 30%, 32%, 33%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 48%, 50%, 52%, 53%, 55%, 56%, 57%, 58%, 59%, etc.).

[0034] According to some preferred aspects of the invention, the grafting rate of maleic anhydride in the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 1.0%-1.8% (e.g., it can be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, etc.).

[0035] According to some preferred aspects of the invention, the intrinsic viscosity of the polyphenylene ether is 0.35-0.5 dl / g (e.g., it can be 0.35 dl / g, 0.4 dl / g, 0.45 dl / g, 0.5 dl / g, etc.).

[0036] In this invention, the test method for "intrinsic viscosity" is determined according to GB / T 1632.1-2020 (or ISO 1628-1:2021), the solvent is chloroform, and the test temperature is 25℃.

[0037] According to some preferred aspects of the present invention, the polyurethane flame retardant material is prepared by the following method: mixing and extruding a hydrogenated styrene-butadiene block copolymer, a maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer and a polyphenylene ether to form a masterbatch; then mixing and extruding the masterbatch, a thermoplastic polyurethane resin and a flame retardant.

[0038] Another technical solution provided by the present invention: a method for preparing the above-mentioned polyurethane flame retardant material, the preparation method comprising:

[0039] The hydrogenated styrene-butadiene block copolymer, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer and polyphenylene ether are mixed according to the formula, then extruded and granulated to obtain the masterbatch.

[0040] The thermoplastic polyurethane resin of the formula is dried, mixed with masterbatch and flame retardant, then extruded and granulated to obtain polyurethane flame retardant material.

[0041] In some embodiments of the present invention, the extrusion temperature is 170-260°C during the preparation of the masterbatch.

[0042] Furthermore, in the process of preparing the masterbatch, the extrusion is carried out using a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are as follows: Zone 1 170-190℃, Zone 2 190-230℃, Zone 3 210-250℃, Zone 4 230-260℃, Zone 5 230-260℃, Zone 6 230-260℃, Zone 7 230-260℃, Zone 8 230-250℃, Zone 9 220-240℃, Die head 200-220℃, and screw speed 200-350 rpm.

[0043] In some embodiments of the present invention, during the preparation of polyurethane flame-retardant materials by mixing thermoplastic polyurethane resin, masterbatch, flame retardant, etc., the extrusion temperature is 130-210°C.

[0044] Furthermore, in the process of preparing polyurethane flame-retardant materials by mixing thermoplastic polyurethane resin, masterbatch, flame retardant, etc., the extrusion is carried out using a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are as follows: Zone 1 130-150℃, Zone 2 170-190℃, Zone 3 180-200℃, Zone 4 190-210℃, Zone 5 190-210℃, Zone 6 190-210℃, Zone 7 190-210℃, Zone 8 180-200℃, Zone 9 180-200℃, Die head 180-200℃, and screw speed 200-350 rpm.

[0045] Another technical solution provided by the present invention: a charging port cover for new energy vehicles, wherein the raw material of the charging port cover for new energy vehicles includes the polyurethane flame-retardant material described above.

[0046] In some embodiments of the present invention, polyurethane flame-retardant material is used to make a charging port cover for new energy vehicles by injection molding.

[0047] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0048] Based on the problems existing in the preparation of products such as charging port covers for new energy vehicles using polyurethane materials, the inventors of this invention, through extensive experimental research, proposed a carbon-forming flame-retardant system using polyphenylene ether, surface-modified phosphorus-based flame retardants, and surface-modified nitrogen-based flame retardants. This system solves the problem of TPU flame retardant dripping, while simultaneously improving the material's high-temperature resistance and water resistance. The synergistic effect of the surface modification of the flame retardant and maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer improves the compatibility between the flame retardant and polyurethane, enhancing the material's mechanical and physical properties, water resistance, and flame retardant performance, and resolving the industry-wide problem of polyurethane materials precipitating whitening. The TPU material prepared by this invention meets the requirements for high flame-retardant polyurethane elastomer materials for electric vehicle charging port covers, namely, achieving the V0 level of flame retardant performance in the UL94 standard, and not cracking or precipitating after being placed in water at 80°C for 168 hours. Detailed Implementation

[0049] Charging port covers for new energy vehicles need to maintain high sealing performance and structural stability over long periods in complex environments. However, current materials suffer from various issues, including poor injection elasticity, poor flame retardancy, heavy weight, and poor insulation. While polyurethane materials offer good elasticity, they also suffer from poor flame retardancy, particularly at high temperatures where they are prone to forming molten droplets (potentially causing fires). Furthermore, flame retardants can migrate and leach out, resulting in a "whitening" appearance on the product. Additionally, their water resistance needs further improvement. Therefore, developing a polyurethane flame-retardant material that combines good mechanical properties, good water resistance, meets UL94 V-0 standards, and is environmentally friendly and does not leach out is crucial for improving the reliability of new energy vehicle components.

[0050] Based on this, the inventors of this invention propose a novel polyurethane flame retardant material that can solve the above problems, comprising thermoplastic polyurethane resin, hydrogenated styrene-butadiene block copolymer, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, polyphenylene ether, and a flame retardant, wherein the flame retardant comprises a silane-modified phosphorus flame retardant and a silane-modified nitrogen flame retardant.

[0051] Furthermore, the main concept of this invention lies in:

[0052] (1) In the system of this invention, phosphorus-based flame retardant is the acid source, polyphenylene ether is the carbon source, and nitrogen-based flame retardant is the gas source. When the material is heated, the acid source first decomposes to produce acid. The acid catalyzes the dehydration, esterification, and cross-linking of the carbon source to form a viscous, carbon-rich molten precursor. At the same time, the acid source itself or its decomposition products melt, increasing the viscosity of the system. As the temperature continues to rise, the gas source decomposes to produce a large amount of non-combustible gas. The gas forms bubbles in the viscous molten mixture, driving the entire system to expand. Under high temperature and acid catalysis, the expanded foam further dehydrates and graphitizes, forming a three-dimensional network carbon layer with rigidity, porosity, and heat insulation properties. The dense carbon layer isolates external heat from the interior, protecting the substrate. The large number of closed bubbles in the carbon layer have extremely low thermal conductivity, effectively blocking heat. The carbon layer prevents external oxygen from entering and also prevents internal combustible degradation products from escaping. After the viscous melt expands and solidifies, its viscosity increases significantly, effectively inhibiting molten dripping.

[0053] (2) The surface-modified flame retardant used in this invention achieves a certain degree of compatibility with TPU (mainly soft segments) through its organic modified layer. The maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer (MAH-g-SEBS) strongly "grabs" the flame retardant (or its modified layer) through its MAH groups (mainly through some bonding, such as strong hydrogen bonds formed between MAH and polar groups on the flame retardant surface; the carboxyl groups of MAH can form ionic bonds with metal cations). At the same time, it strongly "grabs" the soft and hard segments of TPU through its SEBS segments and MAH groups. The molecular chain entanglement of the non-polar EB segments in SEBS with the soft segments of TPU, and the hydrogen bonding between MAH and the hard segments of TPU, achieve multi-level interfacial bonding between the flame retardant and the matrix. The synergistic effect of these two factors constructs an extremely strong and compatible interfacial transition layer between the flame retardant and the TPU matrix. This transition layer acts like a "super glue" and "buffer," more firmly "locking" flame retardant molecules within the polymer network. This stronger physical constraint (entanglement and coating) significantly increases the resistance to their migration from the matrix to the surface, substantially reducing the migration ability of small-molecule flame retardants or additives. Surface modification improves dispersion; MAH-g-SEBS further stabilizes the dispersion, preventing excessively high local flame retardant concentrations (exceeding the solubility limit) and reducing the driving force for precipitation. The strengthened interface reduces the interfacial tension between the flame retardant phase and the TPU phase, inhibiting phase separation, a precursor to precipitation. Through this synergistic effect, the stability of the flame retardant in the TPU matrix is ​​significantly improved. Even under long-term use, temperature changes, or high humidity environments, its tendency to migrate and precipitate to the surface is greatly suppressed, effectively solving the problem of surface whitening.

[0054] (3) This invention introduces hydrogenated styrene-butadiene block copolymer, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and polyphenylene ether to improve the high temperature resistance and water resistance of the material. Polyphenylene ether provides basic high heat resistance and high water resistance. Hydrogenated styrene-butadiene block copolymer toughens polyphenylene ether and improves processability. Its own saturated structure ensures its stability and low water absorption in high temperature / humidity environments. Maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, as a highly efficient compatibilizer, establishes a strong chemical bond interface between polyphenylene ether and hydrogenated styrene-butadiene block copolymer through chemical reaction (for example, the maleic anhydride group of MAH-g-SEBS undergoes ring-opening esterification reaction with the phenolic hydroxyl group at the end of polyphenylene ether during melt blending to form a covalent ester bond interface; at the same time, its SEBS segments are physically interlocked with the amorphous region of polyphenylene ether through molecular entanglement, synergistically improving the stability of phase domains. This chemical bond interface significantly inhibits phase separation and water penetration in high temperature / high humidity environments, enabling the composite material to maintain durable performance). This strong interface is key to improving high-temperature resistance: it effectively transfers stress at high temperatures, maintaining the integrity, dimensional stability, and mechanical strength of the composite material, and preventing failure due to thermal stress or creep. This strong interface is also crucial for improving water resistance: it eliminates the main pathway for moisture penetration (weak physical interface), significantly reducing the risk of swelling, delamination, and hydrolysis in aqueous environments, maintaining the inherent low water absorption and long-term performance stability of PPO, thereby enhancing both the material's high-temperature resistance and water resistance.

[0055] In summary, in this invention: 1) using a TPU substrate can reduce the hardness of the charging port cover and improve the elasticity of the material; 2) using a flame retardant system of polyphenylene ether, surface-modified phosphorus-based flame retardant, and surface-modified nitrogen-based flame retardant solves the problem of TPU flame retardant dripping, while improving the material's high-temperature resistance and water resistance; 3) the synergistic effect of the surface-modified flame retardant and maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer improves the compatibility between the flame retardant and polyurethane, improves the material's mechanical and physical properties, water resistance, and flame retardant properties, and solves the industry-wide problem of polyurethane materials precipitating white.

[0056] Furthermore, in the system of this invention, the mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 5-25:0.3-3.0:0.2-2:1; the mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.15-0.45:0.1-0.4. These ratios are preferred ratios derived from extensive practical experience by the inventors, and can achieve better results.

[0057] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0058] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0059] The silane-modified aluminum hypophosphite was obtained as follows: Aluminum hypophosphite was pre-dried in a vacuum drying oven at 80℃ for 4 hours to remove adsorbed moisture; the moisture content after drying was approximately 0.2%. After drying, it was sieved (using a 250-mesh sieve) to ensure uniform particle dispersion. The dried aluminum hypophosphite was added to anhydrous ethanol (100g aluminum hypophosphite to 800mL ethanol); under a 50℃ water bath, it was treated with an ultrasonic disperser (300W power, 40kHz frequency) for 30 minutes to form a uniform suspension. The silane coupling agent γ-aminopropyltriethoxysilane (KH550) was weighed according to the specified ratio; the silane coupling agent KH550 was slowly added dropwise to the suspension while mechanically stirring at 600rpm; after the addition was complete, the temperature was raised to 60±2℃ and the reaction was maintained at this temperature for 2 hours, with nitrogen gas purging throughout to isolate oxygen; stirring was maintained at 300rpm during the reaction to ensure complete hydrolysis of the silane and reaction with the hydroxyl groups on the surface of the hypophosphite. After the reaction was complete, the mixture was vacuum filtered through a Buchner funnel to collect the solid product. The solid product was washed three times with anhydrous ethanol (100 mL each time) to thoroughly remove unreacted KH550 and byproducts. The filter cake was transferred to an 80°C vacuum drying oven and dried for 12 hours to obtain a white powdery silane-modified aluminum hypophosphite. The mass ratio of aluminum hypophosphite to the silane coupling agent KH550 was 100:2.

[0060] The silane-modified melamine cyanurate was obtained as follows: Melamine cyanurate was pre-dried in a vacuum drying oven at 80℃ for 4 hours to remove adsorbed moisture, resulting in a moisture content of approximately 0.15%. The dried MCA was added to toluene at a solid-liquid ratio of 1:10 (g / mL); the mixture was then treated with an ultrasonic disperser (300W power, 40kHz frequency) for 30 minutes to ensure uniform dispersion of the MCA in the toluene, forming a stable suspension. The silane coupling agent γ-methacryloyloxypropyltrimethoxysilane (KH570) was weighed according to the specified ratio; the silane coupling agent KH570 was slowly added dropwise to the suspension while mechanically stirring at 600rpm; after the addition was complete, nitrogen gas was purged throughout to isolate oxygen, and ultrasonic treatment was continued for 1 hour (300W power, temperature controlled at 55℃) to promote the hydrolysis of the silane coupling agent and its grafting onto the MCA surface. After the reaction was completed, the mixture was vacuum filtered through a Buchner funnel to collect the solid product; it was washed three times with anhydrous toluene to remove unreacted KH570 and byproducts; the product was then dried in a vacuum drying oven at 80°C for 8 hours to obtain a white powdery silane-modified melamine cyanurate. The mass ratio of MCA to silane coupling agent was 100:5.

[0061] Example 1

[0062] This example provides a polyurethane flame retardant material and its preparation method. The formulation of the polyurethane flame retardant material is shown in Table 1.

[0063] Table 1

[0064]

[0065] The preparation method of this polyurethane flame retardant material includes:

[0066] Step 1: Weigh out 5 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 5 parts by weight of polyphenylene ether, and 0.1 parts by weight of antioxidant 1010, place them in a high-speed mixer, and mix for 5 minutes to obtain a mixture.

[0067] Step 2: Feed the mixture obtained in Step 1 into a twin-screw extruder, and after extrusion and granulation, obtain masterbatch;

[0068] Step 3: Pre-dry the TPU in a 100℃ drying oven for 4 hours to remove adsorbed moisture. Weigh out 55.5 parts TPU resin, 14.1 parts masterbatch, 18 parts silane-modified hypophosphite, 12 parts silane-modified melamine cyanurate, and 0.4 parts antioxidant 1010 by weight, place them in a high-speed mixer, and mix for 5 minutes to obtain the mixture.

[0069] Step 4: Feed the mixture obtained in Step 3 into a twin-screw extruder, and after extrusion and granulation, obtain polyurethane flame retardant material.

[0070] In the second step, the temperature of the twin-screw extruder is set to 170-260℃, with zone 1 at 180℃, zone 2 at 210℃, zone 3 at 235℃, zone 4 at 245℃, zone 5 at 245℃, zone 6 at 245℃, zone 7 at 245℃, zone 8 at 240℃, zone 9 at 230℃, the die head at 210℃, and the screw speed at 300 rpm.

[0071] The temperature of the twin-screw extruder in step four is set to 130-210℃, with zone 1 at 140℃, zone 2 at 175℃, zone 3 at 185℃, zone 4 at 195℃, zone 5 at 195℃, zone 6 at 195℃, zone 7 at 195℃, zone 8 at 185℃, zone 9 at 185℃, the die head at 180℃, and the screw speed at 280 rpm.

[0072] The hydrogenated styrene-butadiene block copolymer is a hydrogenated polystyrene-polybutadiene-polystyrene block copolymer with a styrene content of 30% (purchased from Kraton, grade G1650). The maleic anhydride grafting rate in the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 1.0% (purchased from Kraton, grade FG1924). The intrinsic viscosity of polyphenylene oxide (PPO) is 0.40 dl / g (purchased from Nantong Xingchen Synthetic Materials Co., Ltd. Ruicheng Branch, grade LXR040). The TPU is BASF 1185A.

[0073] Example 2

[0074] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that: the hydrogenated styrene-butadiene block copolymer is a hydrogenated polystyrene-polybutadiene-polystyrene block copolymer with a styrene content of 33% (purchased from Kraton, grade G1651), the maleic anhydride grafting rate in the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 1.5% (purchased from Ningbo Nengzhiguang, grade GPM5601), and the intrinsic viscosity of polyphenylene ether (PPO) is 0.45 dl / g (purchased from Nantong Xingchen Synthetic Materials Co., Ltd. Ruicheng Branch, grade LXR045).

[0075] Example 3

[0076] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that: the hydrogenated styrene-butadiene block copolymer is a hydrogenated polystyrene-polybutadiene-polystyrene block copolymer with a styrene content of 42% (purchased from Kraton, grade A1536), the maleic anhydride grafting rate in the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 1.7% (purchased from Kraton, grade FG1924), and the intrinsic viscosity of polyphenylene ether (PPO) is 0.35 dl / g (purchased from Nantong Xingchen Synthetic Materials Co., Ltd. Ruicheng Branch, grade LXR035).

[0077] Example 4

[0078] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that the formulation of the polyurethane flame retardant material is shown in Table 2.

[0079] Table 2

[0080]

[0081]

[0082] Example 5

[0083] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that the formulation of the polyurethane flame retardant material is shown in Table 3.

[0084] Table 3

[0085]

[0086] Comparative Example 1

[0087] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that: silane-modified aluminum hypophosphite is replaced with an equal mass of zinc stearate-modified aluminum hypophosphite (purchased from Zhejiang Xusen Flame Retardant Technology Co., Ltd., brand name XS-FR-T300), and silane-modified melamine cyanurate is replaced with an equal mass of zinc stearate-modified melamine cyanurate (purchased from Zhejiang Xusen Flame Retardant Technology Co., Ltd., brand name XS-MC-151).

[0088] Comparative Example 2

[0089] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that the polyphenylene ether is replaced with an equal mass of polystyrene (purchased from Panjin Petrochemical, grade 825).

[0090] Comparative Example 3

[0091] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as Example 1, except that the amount of polyphenylene ether added is 15 parts, and the specific raw material formulation is shown in Table 4.

[0092] Table 4

[0093]

[0094]

[0095] Comparative Example 4

[0096] This example provides a polyurethane flame retardant material and its preparation method, which is basically the same as in Example 1, except that the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is replaced with an equal mass of hydrogenated styrene-butadiene block copolymer with the same styrene content (purchased from Kraton, grade G1645).

[0097] Performance testing

[0098] The polyurethane flame-retardant materials obtained in Examples 1-5 and Comparative Examples 1-4 were subjected to the following performance tests, and the specific results are shown in Tables 5-6. Specifically, the mechanical properties and aging resistance of the polyurethane flame-retardant materials were tested according to GB / T 2951, the water resistance was tested according to GB / T 33594, and the flame-retardant performance was determined according to UL94 vertical burning test.

[0099] Table 5

[0100]

[0101]

[0102] Table 6

[0103]

[0104] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0105] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A polyurethane flame-retardant material comprising thermoplastic polyurethane resin and a flame retardant, characterized in that, The polyurethane flame retardant material further comprises hydrogenated styrene-butadiene block copolymer, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer and polyphenylene ether, and the flame retardant comprises silane-modified phosphorus flame retardant and silane-modified nitrogen flame retardant. The mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 5-25:0.3-3.0:0.2-2:

1. The mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.15-0.45:0.1-0.

4.

2. The polyurethane flame-retardant material according to claim 1, characterized in that, The mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 6-23.5:0.35-2.8:0.25-2:1; and / or, The mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.17-0.4:0.1-0.

35.

3. The polyurethane flame-retardant material according to claim 2, characterized in that, The mass ratio of the thermoplastic polyurethane resin, the hydrogenated styrene-butadiene block copolymer, the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and the polyphenylene ether is 8-15:0.5-1.5:0.4-1.2:1; and / or, The mass ratio of the thermoplastic polyurethane resin, the silane-modified phosphorus flame retardant, and the silane-modified nitrogen flame retardant is 1:0.25-0.38:0.15-0.

25.

4. The polyurethane flame-retardant material according to claim 1, characterized in that, By weight, the polyurethane flame retardant material comprises: 50-70 parts of thermoplastic polyurethane resin, 3-8 parts of hydrogenated styrene-butadiene block copolymer, 2-6 parts of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 3-8 parts of polyphenylene ether, 12-20 parts of silane-modified phosphorus flame retardant, 8-16 parts of silane-modified nitrogen flame retardant, and 0.2-1.0 parts of antioxidant.

5. The polyurethane flame-retardant material according to claim 1, characterized in that, The silane-modified phosphorus-based flame retardant is prepared by reacting a silane coupling agent with a phosphorus-based flame retardant, and the silane-modified nitrogen-based flame retardant is prepared by reacting a silane coupling agent with a nitrogen-based flame retardant.

6. The polyurethane flame-retardant material according to claim 5, characterized in that, The silane coupling agent is γ-aminopropyltriethoxysilane and / or γ-methacryloyloxypropyltrimethoxysilane; and / or... In the preparation of the silane-modified phosphorus-based flame retardant, the mass ratio of silane coupling agent to phosphorus-based flame retardant is 1-5:100; and / or, In the preparation of the silane-modified nitrogen-based flame retardant, the mass ratio of silane coupling agent to nitrogen-based flame retardant is 3-8:100; and / or, The phosphorus-based flame retardant is a hypophosphite, and the phosphorus-based flame retardant is melamine cyanurate; and / or, The mass ratio of the silane-modified phosphorus-based flame retardant to the silane-modified nitrogen-based flame retardant is 1-3:

1.

7. The polyurethane flame-retardant material according to claim 1, characterized in that, The thermoplastic polyurethane resin has a Shore hardness of 80A-95A and a melt index of 2-30 g / 10 min measured at 190°C and 2.16 kg; and / or, The styrene content in the hydrogenated styrene-butadiene block copolymer is 25%-60%; and / or, The maleic anhydride grafting rate in the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 1.0%-1.8%; and / or, The intrinsic viscosity of the polyphenylene ether is 0.35-0.5 dl / g; and / or, The thermoplastic polyurethane resin content in the polyurethane flame retardant material is above 50% by mass percentage.

8. The polyurethane flame-retardant material according to claim 1, characterized in that, The polyurethane flame-retardant material is prepared by the following method: hydrogenated styrene-butadiene block copolymer, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, and polyphenylene ether are mixed and extruded to form a masterbatch; then the masterbatch, thermoplastic polyurethane resin, and flame retardant are mixed and extruded; and / or, The thermoplastic polyurethane resin content in the polyurethane flame retardant material is 50%-70% by weight.

9. A method for preparing the polyurethane flame-retardant material according to any one of claims 1-8, characterized in that, The preparation method includes: The hydrogenated styrene-butadiene block copolymer, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer and polyphenylene ether are mixed according to the formula, then extruded and granulated to obtain the masterbatch. The thermoplastic polyurethane resin of the formula is dried, mixed with masterbatch and flame retardant, then extruded and granulated to obtain polyurethane flame retardant material.

10. A charging port cover for a new energy vehicle, characterized in that, The raw material of the new energy vehicle charging port cover includes the polyurethane flame-retardant material described in any one of claims 1-8.

Images