Halogen-free flame-retardant TPU material suitable for charging pile cable and preparation method of halogen-free flame-retardant TPU material

Abstract

The invention discloses a halogen-free flame-retardant TPU (thermoplastic polyurethane) material suitable for a charging pile cable and a preparation method of the halogen-free flame-retardant TPU material, belongs to the technical field of TPU material processing, and aims to solve the technical problem that the flame retardance and wear resistance of a TPU material for a cable in the prior art need to be further improved. The material comprises the following raw material components in parts by weight: 80-100 parts of a cross-linked thermoplastic elastomer, 10-20 parts of a modified filler, 10-20 parts of a flame-retardant chain extender, 3-5 parts of a stabilizer, 3-5 parts of an antioxidant, 3-5 parts of an ultraviolet light absorber and 3-5 parts of a lubricant, after the modified thermoplastic elastomer is prepared, the modified thermoplastic elastomer is activated and cross-linked with the flame-retardant cross-linking agent, a silane structure is introduced into the structure, the flame-retardant cross-linking agent and the modified filler enhance the flame-retardant capability of the material through a synergistic effect, and meanwhile, the compatibility of the material and an inorganic material is enhanced by hybridizing a polyurethane chain segment; the wear resistance, flame retardance and other properties of the material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of TPU material processing, and in particular to a halogen-free flame-retardant TPU material suitable for charging pile cables and a preparation method thereof. Background Art

[0002] The development of flame-retardant TPU cable materials is mainly to meet the safety requirements of electric vehicle charging piles. Early TPU was widely used in the cable industry due to its excellent physical properties and processing flexibility. However, early TPU materials had deficiencies in flame retardancy. Moreover, with the improvement of environmental protection standards, the research and development focus has shifted to non-halogen flame retardant technology, which not only meets environmental protection requirements but also maintains the mechanical strength and chemical resistance of the material. Modern flame-retardant TPU cable materials not only pass strict flame retardant tests, but also withstand high temperatures and chemical corrosion, meet high safety and environmental protection standards, and become an ideal choice for charging pile cables.

[0003] Prior art CN113881216B discloses a wear-resistant flame-retardant modified polyurethane cable material and a preparation method thereof, which is made of thermoplastic polyurethane, polyolefin elastomer and modifier, wherein the modifier includes a compatibilizer, a synergistic flame retardant and a filler, wherein the compatibilizer is at least one of maleic anhydride grafted EVA and a silane coupling agent, the synergistic flame retardant is a composition of diethyl aluminum phosphinate and nano magnesium hydroxide, and the filler is at least two of nano calcium carbonate, nano aluminum oxide and nano carbon black; the invention uses thermoplastic polyurethane as a matrix material, and improves the flame retardant properties of the thermoplastic polyurethane by blending a polyolefin elastomer and a modifier, while taking into account the improvement of its wear resistance.

[0004] However, the above patent content is to achieve the technical effect of improving the wear resistance and flame retardancy of the material by melt extrusion of thermoplastic polyurethane and auxiliary materials. However, the synergistic flame retardant is a composition of diethyl aluminum phosphinate and nano magnesium hydroxide. The polarity difference between the two is large, resulting in weak interface bonding force, which leads to weak dispersion performance and synergistic coordination ability of the two in the organic system. Therefore, the flame retardant performance of the material needs to be further improved. In addition, the polarity difference between inorganic components such as fillers and thermoplastic polyurethane is also large, which will also lead to poor compatibility between the overall materials, making the wear resistance performance need to be further improved.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0006] The object of the present invention is to provide a halogen-free flame-retardant TPU material suitable for charging pile cables and a preparation method thereof, so as to solve the technical defects proposed by the background technology.

[0007] The object of the present invention can be achieved by the following technical scheme: a halogen-free flame-retardant TPU material suitable for charging pile cables, comprising the following raw material components in parts by weight: 80-100 parts of a cross-linked thermoplastic elastomer, 10-20 parts of a modified filler, 10-20 parts of a flame retardant chain extender, 3-5 parts of a stabilizer, 3-5 parts of an antioxidant, 3-5 parts of an ultraviolet absorber, and 3-5 parts of a lubricant;

[0008] Among them, the preparation method of the cross-linked thermoplastic elastomer is as follows: 8-10 parts of activated thermoplastic elastomer, 3-5 parts of flame retardant chain extender, 0.5-0.8 parts of triethylamine and 40-60 parts of N,N-dimethylformamide are weighed by weight, added into a reactor and stirred, the temperature of the reactor is increased to 80-100°C, the reaction is kept warm for 2-4 hours, and the cross-linked thermoplastic elastomer is obtained by post-treatment.

[0009] The reaction principle for preparing cross-linked thermoplastic elastomers is as follows: under the catalysis of high temperature and alkaline conditions, the epoxy group in the flame retardant chain extension group undergoes ring opening to generate free radicals that react with the hydroxyl groups in the activated thermoplastic elastomer, ultimately forming a complex spatial network structure to prepare a cross-linked thermoplastic elastomer.

[0010] Furthermore, the post-treatment includes: after the reaction is completed, the reactor is cooled to room temperature, the reaction liquid is added into a rotary evaporator with a water bath temperature of 80-100° C., and the reduced pressure distillation is performed until no liquid is extracted to obtain a cross-linked thermoplastic elastomer.

[0011] A further method for preparing the activated thermoplastic elastomer comprises the following steps:

[0012] A1. Add diethylene glycol ether, 1,5-hexadiene-3,4-diol, dibutyltin dilaurate and toluene into a reactor. After the temperature of the reactor is raised to 60-80° C., add toluene-2,6-diisocyanate solution into the reactor and keep the temperature for 2-3 hours. After the reaction is completed, post-process to obtain a modified thermoplastic elastomer.

[0013] The reaction equation for preparing the modified thermoplastic elastomer is:

[0014]

[0015] Where:

[0016] The reaction principle for preparing modified thermoplastic elastomers is as follows: under the catalysis of a catalyst, a polymerization reaction occurs between isocyanate and polyol, and the isocyanate group (-NCO) reacts with the hydroxyl group (-OH) to form a carbamate bond (-NHCOO-). After continuous polymerization and regulation of the amount of reactants, a hydroxyl-terminated modified thermoplastic elastomer is finally prepared.

[0017] A2. Add the oxidizing liquid and N,N-dimethylformamide into a reactor and stir. After the temperature of the reactor drops to 0-5°C, add the modified thermoplastic elastomer into the reactor and keep the temperature for 1-2 hours. After post-treatment, an activated thermoplastic elastomer is obtained.

[0018] The reaction equation for preparing activated thermoplastic elastomer is:

[0019]

[0020] The reaction principle for preparing the activated thermoplastic elastomer is: under alkaline and low temperature conditions, potassium permanganate oxidizes the double bonds in the modified thermoplastic elastomer into hydroxyl groups, thereby enhancing the reaction activity of the modified thermoplastic elastomer, and finally preparing the activated thermoplastic elastomer.

[0021] Further, in step A1, the dosage ratio of diethylene glycol ether, 1,5-hexadiene-3,4-diol, dibutyltin dilaurate toluene and toluene-2,6-diisocyanate solution is 4-5g:8-10g:0.2-0.5g:40-60mL:10-12mL, and the toluene-2,6-diisocyanate solution is prepared by configuring toluene-2,6-diisocyanate and toluene in a dosage ratio of 1g:2-3mL. The post-treatment includes: after the reaction is completed, the reaction kettle is cooled to room temperature, and the reaction solution is added to a rotary evaporator with a water bath temperature of 80-100°C. The method comprises the following steps: distilling under reduced pressure until no liquid is extracted to obtain a modified thermoplastic elastomer; in step A2, the amount ratio of the oxidizing liquid, N,N-dimethylformamide and the modified thermoplastic elastomer is 3-5mL:20-30mL:5-8g, the oxidizing liquid is prepared by preparing potassium permanganate, sodium hydroxide and deionized water in an amount ratio of 3-5g:0.3-0.5g:20-30mL, and the post-treatment comprises: after the reaction is completed, the reactor is heated to room temperature, the reaction liquid is added to a rotary evaporator with a water bath temperature of 80-100°C, and distilling under reduced pressure until no liquid is extracted to obtain an activated thermoplastic elastomer.

[0022] Furthermore, the preparation method of the flame retardant chain extender comprises the following steps:

[0023] B1. Add flame retardant monomer, (2-methyl-2-propylene) succinic anhydride, platinum tetrachloride and dimethyl sulfoxide into a reaction kettle, introduce nitrogen protection, raise the temperature of the reaction kettle to 120-140° C., keep the temperature for reaction for 2-4 hours, and post-treat to obtain a reaction precursor;

[0024] The reaction equation for preparing the reaction precursor is:

[0025]

[0026] Where:

[0027] The reaction principle for preparing the reaction precursor is: under the catalysis of a catalyst and high temperature and under the protection of a nitrogen atmosphere, the silicon-hydrogen bonds of the flame retardant monomer undergo a silicon-hydrogen addition reaction with the double bonds on (2-methyl-2-propylene) succinic anhydride to finally prepare the reaction precursor. The mass spectrometry analysis data of the reaction precursor are m / z: 454.14 (100.0%), 455.14 (31.5%), 456.14 (5.6%), 456.13 (3.4%), and 457.14 (1.4%).

[0028] B2. Add the reaction precursor, N,N'-di(2-hydroxyethyl)-1,3-propylenediamine, chlorine trichloride and pyridine into the reaction kettle, raise the temperature of the reaction kettle to 80-100°C, keep the temperature for 2-3h, and post-treat to obtain the modified flame retardant;

[0029] The reaction equation for preparing the modified flame retardant is:

[0030]

[0031] The reaction principle for preparing the modified flame retardant is as follows: under the catalysis of a catalyst and high temperature, the secondary amino group in the reaction precursor undergoes a ring-opening reaction with N,N'-di(2-hydroxyethyl)-1,3-propylenediamine to generate an amide and a carboxyl group, and the carboxyl group further reacts with the hydroxyl group on N,N'-di(2-hydroxyethyl)-1,3-propylenediamine to further cross-link to form a complex spatial network structure, and finally the modified flame retardant is prepared.

[0032] B3. Add modified flame retardant, epichlorohydrin, sodium carbonate, triethyl borate and ethyl acetate into the reactor, lower the temperature of the reactor to 0-5°C, keep the reaction temperature for 1-2h, and post-treat to obtain flame retardant chain extender.

[0033] The reaction equation for preparing the flame retardant chain extender is:

[0034]

[0035] The reaction principle for preparing the flame retardant chain extender is as follows: under the catalysis of weak alkalinity and low temperature, the epoxy group is protected, a large number of hydroxyl groups on the modified flame retardant react with the chlorine groups on epichlorohydrin, a large number of epoxy groups are introduced into the modified flame retardant, and finally the flame retardant chain extender is prepared.

[0036] Further, in step B1, the amount ratio of the flame retardant monomer, (2-methyl-2-propylene) succinic anhydride, platinum tetrachloride and dimethyl sulfoxide is 8-10g:4-5g:0.3-0.5g:40-60mL, and the post-treatment includes: after the reaction is completed, the nitrogen is turned off after the reactor is cooled to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80-100°C, and the reaction is distilled under reduced pressure until no liquid is extracted to obtain a reaction precursor; in step B2, the amount ratio of the reaction precursor, N,N'-bis(2-hydroxyethyl)-1,3-propylenediamine, chlorine trichloride and pyridine is 8-10g:3-5g:0.3-0.5g: 40-60mL, post-treatment includes: after the reaction is completed, the reaction kettle is lowered to room temperature, the reaction liquid is added to a rotary evaporator with a water bath temperature of 80-100°C, and the reduced pressure distillation is performed until no liquid is produced to obtain a modified flame retardant; in step B3, the amount ratio of the modified flame retardant, epichlorohydrin, sodium carbonate, triethyl borate and ethyl acetate is 8-10g:4-5g:1-2g:0.3-0.5g:40-60mL, and the post-treatment includes: after the reaction is completed, the reaction kettle is lowered to room temperature, the reaction liquid is added to a rotary evaporator with a water bath temperature of 80-100°C, and the reduced pressure distillation is performed until no liquid is produced to obtain a flame retardant chain extender.

[0037] Furthermore, the preparation method of the flame retardant monomer comprises the following steps:

[0038] C1, adding vinylmethylsilane, trimethylchlorosilane, chlorotristriphenylphosphine rhodium and toluene into a reaction kettle, introducing nitrogen protection, reacting at room temperature for 1-2h, and post-treating to obtain modified silane;

[0039] The reaction equation for preparing modified silane is:

[0040]

[0041] The reaction principle for preparing modified silane is: under the catalysis of the catalyst, the silicon-hydrogen bond is activated, and under the protection of nitrogen, an elimination reaction occurs with the silicon-chlorine bond to finally obtain modified silane. The mass spectrometry analysis data of the modified silane are m / z: 158.09 (100.0%), 159.09 (10.2%), 159.10 (7.8%), 160.09 (7.0%), 160.10 (1.1%).

[0042] C2, adding modified silane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakistriphenylphosphine palladium and dimethyl sulfoxide into a reaction kettle, introducing nitrogen protection, raising the temperature of the reaction kettle to 80-100° C., keeping the temperature for reaction for 1-2 hours, and post-treating to obtain phosphosilane;

[0043] The reaction equation for preparing phosphosilane is:

[0044]

[0045] The reaction principle for preparing phosphosilane is as follows: under the catalysis of a catalyst and high temperature, the carbon-carbon double bond on the modified silane reacts with the phosphorus-hydrogen bond on 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to finally prepare phosphosilane. The mass spectrometry analysis data of phosphosilane are m / z: 372.11 (100.0%), 373.12 (20.9%), 373.11 (10.2%), 374.11 (7.0%), 374.12 (4.6%), 375.11 (1.7%).

[0046] C3. Add silyl phosphide, ammonium fluoride and dimethyl sulfoxide into a reactor, introduce nitrogen protection, raise the temperature of the reactor to 80-100° C., keep the temperature for reaction for 1-2 hours, and post-treat to obtain a flame retardant monomer.

[0047] The reaction equation for preparing the flame retardant monomer is:

[0048]

[0049] The reaction principle for preparing the flame retardant monomer is as follows: the fluoride ions in ammonium fluoride carry out nucleophilic attack on the silicon atom on the trimethylsilyl group. Due to the strong silicon-fluorine bond formed between the fluorine atom and the silicon atom, the trimethylsilyl group is separated from the molecule. After the trimethylsilyl group is removed, the shielded Si-H bond is exposed again to obtain the flame retardant monomer. The mass spectrometry data of the flame retardant monomer are m / z: 300.07 (100.0%), 301.08 (17.6%), 301.07 (5.1%), 302.07 (3.4%), 302.08 (2.8%).

[0050] Further, in step C1, the amount ratio of vinylmethylsilane, trimethylchlorosilane, chlorotriphenylphosphine rhodium and toluene is 4-6g:3-5g:0.3-0.5g:40-60mL, and the post-treatment includes: after the reaction is completed, the nitrogen is turned off after the reactor is cooled to room temperature, and the reaction solution is added to a rotary evaporator with a water bath temperature of 80-100°C, and the reduced pressure distillation is carried out until no liquid is extracted to obtain modified silane; in step C2, the amount ratio of modified silane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakistriphenylphosphine palladium and dimethyl sulfoxide is 4-6g:8-10g :0.3-0.5g:40-60mL, post-treatment includes: after the reaction is completed, the nitrogen is turned off after the reactor is lowered to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80-100°C, and distilled under reduced pressure until no liquid is produced to obtain phosphosilane; in step C3, the amount ratio of phosphosilane, ammonium fluoride and dimethyl sulfoxide is 4-6g:1-2g:20-30mL, and the post-treatment includes: after the reaction is completed, the nitrogen is turned off after the reactor is lowered to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80-100°C, and distilled under reduced pressure until no liquid is produced to obtain a flame retardant monomer.

[0051] Furthermore, the preparation method of the modified filler comprises the following steps:

[0052] D1. Add magnesium hydroxide and aluminum hydroxide into a grinder, grind and mix evenly, and sieve to obtain a mixed powder;

[0053] D2. Add flame retardant powder, triethylamine and deionized water into a reactor and stir. After the temperature of the reactor is reduced to 0-5°C, add 3-(2,3-epoxypropoxy)propyltrimethoxysilane into the reactor and keep the temperature for 30-40 minutes. Post-process and obtain the modified filler.

[0054] The reaction principle for preparing modified fillers is:

[0055] Furthermore, in step D1, the dosage ratio of magnesium hydroxide to aluminum hydroxide is 1g:2-3g, and the mesh size of the sieve is 300-600 mesh; in step D2, the stirring rate of the reactor is 80-120rpm, and the dosage ratio of flame retardant powder, triethylamine, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and deionized water is 8-10g:0.3-0.5g:2-3g:40-60mL, and the post-treatment includes: after the reaction is completed, the reactor is heated to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is placed in a drying oven at a temperature of 60°C for vacuum drying until the filter cake has a constant weight to obtain a modified filler.

[0056] A method for preparing a halogen-free flame-retardant TPU material suitable for charging pile cables comprises the following steps:

[0057] S1, adding a cross-linked thermoplastic elastomer, a modified filler, a flame retardant chain extender, a stabilizer, an antioxidant, an ultraviolet absorber and a lubricant into a stirring tank, and mixing them uniformly to obtain a TPU material;

[0058] S2, adding the TPU material precursor into a twin-screw extruder, and melt-extrude to obtain the TPU material.

[0059] Furthermore, in step S2, the temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 160°C, 165, 265°C, 170°C, 170°C, 180°C, and 180°C respectively, the main engine speed of the twin-screw extruder is 80-120rpm, and the pressure is 100-150bar to obtain TPU material by melt extrusion.

[0060] Furthermore, the stabilizer is one or more of 2-hydroxy-4-n-octyloxybenzophenone, bis(2,2,6,6-tetramethylpiperidinyl)methylene succinate and 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole; the antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl) phosphate and hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; the ultraviolet absorber is one or more of diphenyltriazolyldiphenyltriazoline, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole-4-one) and 2-hydroxy-4-methoxybenzoic acid butyl ester; the lubricant is one or more of calcium stearate, zinc stearate and polyethylene wax.

[0061] The present invention has the following beneficial effects:

[0062] 1. During the combustion of the TPU material prepared by the present invention, the phosphoric acid component in the flame retardant chain extender decomposes to produce acidic substances, which promotes the carbonization of the organic chain segments to form a molten carbon layer. The tertiary amine groups therein decompose to produce a large amount of ammonia, which cooperates with the water vapor generated by the thermal decomposition of the modified filler to take away a large amount of heat, and causes the molten carbon layer to foam to form a flame retardant structure. The metal oxides generated by the high-temperature decomposition of the modified filler form a protective slag layer that cooperates with the foamed carbon layer to isolate the transfer of heat. In addition, the large number of silicon groups in the chain segments give the material a higher ignition point, inhibit the process of thermal decomposition of organic matter, and significantly improve the flame retardancy of the material.

[0063] 2. The present invention prepares an activated thermoplastic elastomer having a large number of active functional groups and cross-links it with a flame retardant chain extender, and introduces a modified filler modified by a silane coupling agent into the system. Under the modification of the silane coupling agent, the interfacial bonding force between the materials is significantly enhanced, and after cross-linking with the flame retardant chain extender, the polyurethane segments form a complex three-dimensional structure, and a silane structure is introduced into the structure. On this basis, the modified filler serves as the skeleton of the TPU material, and the two work together to significantly improve the wear resistance and impact resistance of the material.

[0064] 3. In the process of preparing the flame retardant chain extender, the present invention firstly protects the silicon-hydrogen bond, and then uses a flame retardant organic matter to form a cross-link with the silane structure to form a more stable organic structure. The protective group is removed to give the flame retardant monomer excellent reactivity, and the reactive monomer is cross-linked. The ring opening and cross-linking process of the cyclic anhydride is completed by the selection of reactants. By optimizing the selection of reactants and the reaction process, the reaction steps are simplified, and the process of industrial production of flame retardant chain extenders is further simplified, so that the TPU material prepared by the present invention has excellent industrial prospects. DETAILED DESCRIPTION

[0065] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] Example 1

[0067] This embodiment provides a method for preparing a halogen-free flame-retardant TPU material suitable for charging pile cables, comprising the following steps:

[0068] S1. Preparation of flame retardant monomers

[0069] Weigh: 10.0 g of vinylmethylsilane, 8.0 g of trimethylchlorosilane, 0.8 g of chlorotristriphenylphosphine rhodium and 100.0 mL of toluene, add them into a reactor, introduce nitrogen protection, react at room temperature for 1 h, after the reaction is completed, turn off the nitrogen after the reactor is cooled to room temperature, and add the reaction liquid into a rotary evaporator with a water bath temperature of 80° C., and distill under reduced pressure until no liquid is produced to obtain modified silane;

[0070] Weigh: 12.0 g of modified silane, 18.0 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 0.8 g of tetrakistriphenylphosphine palladium and 100.0 mL of dimethyl sulfoxide, add them into a reactor, introduce nitrogen protection, raise the temperature of the reactor to 80° C., and keep the temperature for reaction for 1 hour. After the reaction is completed, turn off the nitrogen after the reactor is cooled to room temperature, and add the reaction liquid into a rotary evaporator with a water bath temperature of 80° C., and distill under reduced pressure until no liquid is produced to obtain phosphosilane;

[0071] Weigh: 10.0g of silane phosphide, 3.0g of ammonium fluoride and 50.0mL of dimethyl sulfoxide are added to a reactor, and nitrogen is introduced for protection. The temperature of the reactor is raised to 80°C and the reaction is kept warm for 1h. After the reaction is completed, the nitrogen is turned off after the reactor is lowered to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80°C, and distilled under reduced pressure until no liquid is produced to obtain a flame retardant monomer.

[0072] S2. Preparation of flame retardant chain extender

[0073] Weigh: 18.0g flame retardant monomer, 9.0g (2-methyl-2-propylene) succinic anhydride, 0.8g platinum tetrachloride and 100.0mL dimethyl sulfoxide into a reactor, and after nitrogen protection, the temperature of the reactor is raised to 120°C, and the reaction is kept warm for 2h. After the reaction is completed, the nitrogen is turned off after the reactor is cooled to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80°C, and the reaction precursor is obtained by reduced pressure distillation until no liquid is produced;

[0074] Weigh: 16.0 g of reaction precursor, 10.0 g of N, N'-di(2-hydroxyethyl)-1,3-propylenediamine, 0.8 g of chlorine trichloride and 100.0 mL of pyridine and add them into a reactor. The temperature of the reactor is raised to 80°C and kept warm for 2 hours. After the reaction is completed, the reactor is lowered to room temperature and the reaction liquid is added into a rotary evaporator with a water bath temperature of 80°C. The reaction liquid is distilled under reduced pressure until no liquid is extracted to obtain a modified flame retardant.

[0075] Weigh: 18.0g modified flame retardant, 9.0g epichlorohydrin, 3.0g sodium carbonate, 0.8g triethyl borate and 100.0mL ethyl acetate and add them into the reactor, lower the temperature of the reactor to 5°C, and keep the reaction for 1h. After the reaction is completed, lower the reactor to room temperature, add the reaction liquid into a rotary evaporator with a water bath temperature of 80°C, and distill under reduced pressure until no liquid is extracted to obtain a flame retardant chain extender.

[0076] S3. Preparation of cross-linked thermoplastic elastomer

[0077] Weigh: 10.0 g of toluene-2,6-diisocyanate and 30.0 mL of toluene to prepare a toluene-2,6-diisocyanate solution;

[0078] Weigh: 9.0 g of diethylene glycol ether, 18.0 g of 1,5-hexadiene-3,4-diol, 0.8 g of dibutyltin dilaurate and 100.0 mL of toluene are added to a reactor. After the temperature of the reactor is raised to 60° C., 20.0 mL of toluene-2,6-diisocyanate solution is added to the reactor. The reaction is kept warm for 2 hours. After the reaction is completed, the reactor is lowered to room temperature, the reaction liquid is added to a rotary evaporator with a water bath temperature of 80° C., and reduced pressure distillation is performed until no liquid is extracted to obtain a modified thermoplastic elastomer;

[0079] Weigh: 8.0 g potassium permanganate, 0.8 g sodium hydroxide and 50.0 mL deionized water to prepare an oxidation solution;

[0080] Weigh: 8.0 mL of oxidation solution and 50.0 mL of N,N-dimethylformamide were added to the reactor and stirred. After the temperature of the reactor dropped to 5°C, 16.0 g of modified thermoplastic elastomer was added to the reactor and kept warm for 1 hour. After the reaction was completed, the reactor was heated to room temperature and the reaction liquid was added to a rotary evaporator with a water bath temperature of 80°C. The reaction mixture was distilled under reduced pressure until no liquid was extracted to obtain an activated thermoplastic elastomer.

[0081] Weigh: 18.0g activated thermoplastic elastomer, 8.0g flame retardant chain extender, 1.2g triethylamine and 100.0g N,N-dimethylformamide, add into the reactor and stir, raise the temperature of the reactor to 80°C, keep warm for 2h, after the reaction is completed, lower the temperature of the reactor to room temperature, add the reaction liquid into a rotary evaporator with a water bath temperature of 80°C, and distill under reduced pressure until no liquid is extracted to obtain a cross-linked thermoplastic elastomer.

[0082] S4. Preparation of TPU material

[0083] Weigh: 10.0 g of magnesium hydroxide and 20.0 g of aluminum hydroxide, add them into a grinder, grind and mix evenly, and pass through a 300-mesh sieve to obtain a mixed powder;

[0084] Weigh: 18.0 g of flame retardant powder, 0.8 g of triethylamine and 100.0 mL of deionized water are added to a reactor and stirred. After the temperature of the reactor is lowered to 5° C., 5.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane is added to the reactor and the reaction is kept warm for 30 minutes. After the reaction is completed, the reactor is heated to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is placed in a drying oven at a temperature of 60° C. for vacuum drying until the filter cake has a constant weight, thereby obtaining a modified filler;

[0085] Weigh: 88.0 g of a cross-linked thermoplastic elastomer, 16.0 g of a modified filler, 16.0 g of a flame retardant chain extender, 3.6 g of 2-hydroxy-4-n-octyloxybenzophenone, 3.6 g of tris(2,4-di-tert-butylphenyl)phosphate, 3.6 g of diphenyltriazolyldiphenyltriazoline and 3.6 g of polyethylene wax, add them into a stirring tank, mix well to obtain a TPU material precursor;

[0086] The TPU material precursor is added into a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port to the discharge port are 160°C, 165, 265°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 80 rpm and the pressure is 100 bar to obtain the TPU material by melt extrusion.

[0087] Example 2

[0088] This embodiment provides a method for preparing a halogen-free flame-retardant TPU material suitable for charging pile cables, comprising the following steps:

[0089] S1. Preparation of flame retardant monomers

[0090] Weigh: 12.0 g of vinylmethylsilane, 8.0 g of trimethylchlorosilane, 0.8 g of chlorotristriphenylphosphine rhodium and 100.0 mL of toluene, add them into a reactor, introduce nitrogen protection, react at room temperature for 1 h, after the reaction is completed, turn off the nitrogen after the reactor is cooled to room temperature, and add the reaction liquid into a rotary evaporator with a water bath temperature of 80° C., and distill under reduced pressure until no liquid is produced to obtain modified silane;

[0091] Weigh: 10.0 g of modified silane, 18.0 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 0.8 g of tetrakistriphenylphosphine palladium and 100.0 mL of dimethyl sulfoxide, add them into a reactor, introduce nitrogen protection, raise the temperature of the reactor to 80° C., and keep the temperature for reaction for 1 hour. After the reaction is completed, turn off the nitrogen after the reactor is cooled to room temperature, and add the reaction liquid into a rotary evaporator with a water bath temperature of 80° C., and distill under reduced pressure until no liquid is produced to obtain phosphosilane;

[0092] Weigh: 10.0g of phosphosilane, 2.4g of ammonium fluoride and 50.0mL of dimethyl sulfoxide are added to a reactor, and nitrogen is introduced for protection. The temperature of the reactor is raised to 80°C and the reaction is kept warm for 1h. After the reaction is completed, the nitrogen is turned off after the reactor is lowered to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80°C, and distilled under reduced pressure until no liquid is produced to obtain a flame retardant monomer.

[0093] S2. Preparation of flame retardant chain extender

[0094] Weigh: 18.0g flame retardant monomer, 9.0g (2-methyl-2-propylene) succinic anhydride, 1.0g platinum tetrachloride and 100.0mL dimethyl sulfoxide into a reactor, and after nitrogen protection, the temperature of the reactor is raised to 140°C, and the reaction is kept warm for 2h. After the reaction is completed, the nitrogen is turned off after the reactor is cooled to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 80°C, and the reaction precursor is obtained by reduced pressure distillation until no liquid is produced;

[0095] Weigh: 18.0 g of reaction precursor, 9.0 g of N, N'-di(2-hydroxyethyl)-1,3-propylenediamine, 0.8 g of chlorine trichloride and 100.0 mL of pyridine and add them into a reactor. The temperature of the reactor is raised to 80°C and kept warm for 2 hours. After the reaction is completed, the reactor is lowered to room temperature and the reaction liquid is added into a rotary evaporator with a water bath temperature of 100°C. The reaction liquid is distilled under reduced pressure until no liquid is extracted to obtain a modified flame retardant.

[0096] Weigh: 18.0g modified flame retardant, 9.0g epichlorohydrin, 2.4g sodium carbonate, 0.8g triethyl borate and 100.0mL ethyl acetate and add into the reactor, lower the temperature of the reactor to 0°C, keep warm for 2h, after the reaction is completed, lower the reactor to room temperature, add the reaction liquid into a rotary evaporator with a water bath temperature of 100°C, and distill under reduced pressure until no liquid is extracted to obtain a flame retardant chain extender.

[0097] S3. Preparation of cross-linked thermoplastic elastomer

[0098] Weigh: 10.0 g of toluene-2,6-diisocyanate and 20.0 mL of toluene to prepare a toluene-2,6-diisocyanate solution;

[0099] Weigh: 9.0 g of diethylene glycol ether, 18.0 g of 1,5-hexadiene-3,4-diol, 0.8 g of dibutyltin dilaurate and 100.0 mL of toluene are added to a reactor. After the temperature of the reactor is raised to 80° C., 20.0 mL of toluene-2,6-diisocyanate solution is added to the reactor. The reaction is kept warm for 3 hours. After the reaction is completed, the reactor is lowered to room temperature, the reaction liquid is added to a rotary evaporator with a water bath temperature of 100° C., and reduced pressure distillation is performed until no liquid is extracted to obtain a modified thermoplastic elastomer;

[0100] Weigh: 10.0 g potassium permanganate, 0.8 g sodium hydroxide and 50.0 mL deionized water to prepare an oxidation solution;

[0101] Weigh: 10.0 mL of oxidation solution and 50.0 mL of N,N-dimethylformamide were added to the reactor and stirred. After the temperature of the reactor dropped to 0°C, 18.0 g of modified thermoplastic elastomer was added to the reactor and kept warm for 1 hour. After the reaction was completed, the reactor was heated to room temperature and the reaction liquid was added to a rotary evaporator with a water bath temperature of 80°C. The reaction liquid was distilled under reduced pressure until no liquid was extracted to obtain an activated thermoplastic elastomer.

[0102] Weigh: 18.0g activated thermoplastic elastomer, 9.0g flame retardant chain extender, 1.2g triethylamine and 100.0g N,N-dimethylformamide, add into the reactor and stir, raise the temperature of the reactor to 100°C, keep warm and react for 4h. After the reaction is completed, lower the temperature of the reactor to room temperature, add the reaction liquid into a rotary evaporator with a water bath temperature of 80°C, and distill under reduced pressure until no liquid is extracted to obtain a cross-linked thermoplastic elastomer.

[0103] S4. Preparation of TPU material

[0104] Weigh: 10.0 g of magnesium hydroxide and 20.0 g of aluminum hydroxide, add them into a grinder, grind and mix evenly, and pass through a 600-mesh sieve to obtain a mixed powder;

[0105] Weigh: 18.0 g of flame retardant powder, 0.8 g of triethylamine and 100.0 mL of deionized water are added to a reactor and stirred. After the temperature of the reactor is reduced to 0°C, 5.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane is added to the reactor and the reaction is carried out for 30 minutes of heat preservation. After the reaction is completed, the reactor is heated to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is placed in a drying oven at a temperature of 60°C for vacuum drying until the filter cake has a constant weight to obtain a modified filler;

[0106] Weigh: 96.0 g of a cross-linked thermoplastic elastomer, 18.0 g of a modified filler, 18.0 g of a flame retardant chain extender, 4.8 g of 2-hydroxy-4-n-octyloxybenzophenone, 4.8 g of tris(2,4-di-tert-butylphenyl)phosphate, 4.8 g of diphenyltriazolyldiphenyltriazoline and 4.8 g of polyethylene wax, add them into a stirring tank, mix well to obtain a TPU material precursor;

[0107] The TPU material precursor is added into a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port to the discharge port are 160°C, 165, 265°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 120rpm, and the pressure is 150bar to obtain the TPU material by melt extrusion.

[0108] Example 3

[0109] This embodiment provides a method for preparing a halogen-free flame-retardant TPU material suitable for charging pile cables, comprising the following steps:

[0110] S1. Preparation of flame retardant monomers

[0111] Weigh: 10.0 g of vinylmethylsilane, 8.0 g of trimethylchlorosilane, 0.8 g of chlorotristriphenylphosphine rhodium and 100.0 mL of toluene, add them into a reactor, introduce nitrogen protection, react at room temperature for 2 h, after the reaction is completed, turn off the nitrogen after the reactor is cooled to room temperature, and add the reaction liquid into a rotary evaporator with a water bath temperature of 100° C., and distill under reduced pressure until no liquid is produced to obtain modified silane;

[0112] Weigh: 12.0 g of modified silane, 18.0 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 0.8 g of tetrakistriphenylphosphine palladium and 100.0 mL of dimethyl sulfoxide, add them into a reactor, introduce nitrogen protection, raise the temperature of the reactor to 100° C., and keep the temperature for 2 hours. After the reaction is completed, turn off the nitrogen after the reactor is cooled to room temperature, and add the reaction liquid into a rotary evaporator with a water bath temperature of 80° C., and distill under reduced pressure until no liquid is produced to obtain phosphosilane;

[0113] Weigh: 10.0g of silane phosphide, 2.4g of ammonium fluoride and 50.0mL of dimethyl sulfoxide are added to a reactor, and nitrogen is introduced for protection. The temperature of the reactor is raised to 90°C and the reaction is kept warm for 2h. After the reaction is completed, the nitrogen is turned off after the reactor is lowered to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 90°C, and distilled under reduced pressure until no liquid is produced to obtain a flame retardant monomer.

[0114] S2. Preparation of flame retardant chain extender

[0115] Weigh: 18.0g flame retardant monomer, 9.0g (2-methyl-2-propylene) succinic anhydride, 0.8g platinum tetrachloride and 100.0mL dimethyl sulfoxide into a reactor, and after nitrogen protection, the temperature of the reactor is raised to 130°C, and the reaction is kept warm for 3h. After the reaction is completed, the nitrogen is turned off after the reactor is cooled to room temperature, and the reaction liquid is added to a rotary evaporator with a water bath temperature of 90°C, and the reaction precursor is obtained by reduced pressure distillation until no liquid is produced;

[0116] Weigh: 18.0 g of reaction precursor, 8.0 g of N, N'-di(2-hydroxyethyl)-1,3-propylenediamine, 0.8 g of chlorine trichloride and 100.0 mL of pyridine and add them into a reactor. The temperature of the reactor is raised to 90°C and kept warm for 2 hours. After the reaction is completed, the reactor is lowered to room temperature and the reaction liquid is added into a rotary evaporator with a water bath temperature of 90°C. The reaction liquid is distilled under reduced pressure until no liquid is extracted to obtain a modified flame retardant.

[0117] Weigh: 18.0g modified flame retardant, 10.0g epichlorohydrin, 3.6g sodium carbonate, 0.8g triethyl borate and 100.0mL ethyl acetate and add them into the reactor, lower the temperature of the reactor to 3°C, and keep the reaction for 2h. After the reaction is completed, lower the reactor to room temperature, add the reaction liquid into a rotary evaporator with a water bath temperature of 100°C, and distill under reduced pressure until no liquid is extracted to obtain a flame retardant chain extender.

[0118] S3. Preparation of cross-linked thermoplastic elastomer

[0119] Weigh: 10.0 g of toluene-2,6-diisocyanate and 25.0 mL of toluene to prepare a toluene-2,6-diisocyanate solution;

[0120] Weigh: 9.6 g of diethylene glycol ether, 18.0 g of 1,5-hexadiene-3,4-diol, 0.8 g of dibutyltin dilaurate and 100.0 mL of toluene are added to a reactor. After the temperature of the reactor is raised to 70° C., 20.0 mL of toluene-2,6-diisocyanate solution is added to the reactor. The reaction is kept warm for 3 hours. After the reaction is completed, the reactor is lowered to room temperature, the reaction liquid is added to a rotary evaporator with a water bath temperature of 90° C., and reduced pressure distillation is performed until no liquid is extracted to obtain a modified thermoplastic elastomer;

[0121] Weigh: 8.0 g potassium permanganate, 0.8 g sodium hydroxide and 50.0 mL deionized water to prepare an oxidation solution;

[0122] Weigh: 10.0 mL of oxidation solution and 50.0 mL of N,N-dimethylformamide were added to the reactor and stirred. After the temperature of the reactor dropped to 3°C, 16.0 g of modified thermoplastic elastomer was added to the reactor and kept warm for 2 hours. After the reaction was completed, the reactor was heated to room temperature and the reaction liquid was added to a rotary evaporator with a water bath temperature of 90°C. The reaction mixture was distilled under reduced pressure until no liquid was extracted to obtain an activated thermoplastic elastomer.

[0123] Weigh: 18.0g activated thermoplastic elastomer, 10.0g flame retardant chain extender, 1.6g triethylamine and 100.0g N,N-dimethylformamide, add into the reactor and stir, raise the temperature of the reactor to 90°C, keep warm and react for 3h. After the reaction is completed, lower the temperature of the reactor to room temperature, add the reaction liquid into a rotary evaporator with a water bath temperature of 90°C, and distill under reduced pressure until no liquid is extracted to obtain a cross-linked thermoplastic elastomer.

[0124] S4. Preparation of TPU material

[0125] Weigh: 10.0 g of magnesium hydroxide and 25.0 g of aluminum hydroxide, add them into a grinder, grind and mix evenly, and pass through a 450-mesh sieve to obtain a mixed powder;

[0126] Weigh: 18.0g of flame retardant powder, 0.8g of triethylamine and 100.0mL of deionized water are added to a reactor and stirred. After the temperature of the reactor is reduced to 3°C, 6.0g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane is added to the reactor and the reaction is carried out for 30 minutes of heat preservation. After the reaction is completed, the reactor is heated to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is placed in a drying oven at a temperature of 60°C for vacuum drying until the filter cake has a constant weight to obtain a modified filler;

[0127] Weigh: 96.0 g of a cross-linked thermoplastic elastomer, 16.0 g of a modified filler, 16.0 g of a flame retardant chain extender, 4.8 g of 2-hydroxy-4-n-octyloxybenzophenone, 4.8 g of tris(2,4-di-tert-butylphenyl)phosphate, 4.8 g of diphenyltriazolyldiphenyltriazoline and 3.6 g of polyethylene wax, add them into a stirring tank, mix well to obtain a TPU material precursor;

[0128] The TPU material precursor is added into a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port to the discharge port are 160°C, 165, 265°C, 170°C, 170°C, 180°C, and 180°C, respectively. The main engine speed of the twin-screw extruder is 100 rpm and the pressure is 125 bar to obtain the TPU material by melt extrusion.

[0129] Comparative Example 1

[0130] The difference between this comparative example and Example 3 is that step S1 is eliminated, and in step S2, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is used to replace the flame retardant monomer.

[0131] Comparative Example 2

[0132] The difference between this comparative example and Example 3 is that step S1 and step S2 are eliminated, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is used to replace the flame retardant chain extender.

[0133] Comparative Example 3

[0134] The difference between this comparative example and Example 3 is that the activation step of the modified thermoplastic elastomer in step S3 is cancelled, and the modified thermoplastic elastomer is used instead of the activated thermoplastic elastomer in the process of preparing the cross-linked thermoplastic elastomer.

[0135] Performance Testing:

[0136] The combustion performance was tested on the limiting oxygen index of the TPU materials prepared in Examples 1-3 and Comparative Examples 1-3 with reference to the standard GB / T 2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method Part 2: Room Temperature Test";

[0137] The flame retardant properties refer to the standard GB / T 2408-2021 "Horizontal and vertical methods for determination of combustion performance of plastics" for the vertical combustion grades of the TPU materials prepared in Examples 1-3 and Comparative Examples 1-3;

[0138] The relative volume wear and tensile strength of the TPU materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested with reference to the standard GB / T 33091-2016 "Polyurethane sieve plate";

[0139] The cantilever beam impact strength of the TPU materials prepared in Examples 1-3 and Comparative Examples 1-3 was tested with reference to the standard GB / T 1843-2008 "Determination of cantilever beam impact strength of plastics";

[0140] See Table 1 for specific data:

[0141] Table 1-Performance test data of each sample

[0142]

[0143] Data Analysis:

[0144] Comparing and analyzing the data in Table 1 above, the composite polyurethane prepared by the present invention has a limiting oxygen index of 41.3%, a vertical combustion grade of V-0, and a relative volume wear of 38 mm. 3 , tensile strength is 56MPa and cantilever beam impact strength is 66.2kJ·m -2 , all data are better than those of the comparative example, indicating that: the present invention is to prepare a modified thermoplastic elastomer, activate it to introduce a large number of active functional groups and cross-link it with a flame retardant cross-linking agent, introduce a silane structure into the structure, and the flame retardant cross-linking agent and the modified filler enhance the flame retardancy of the material through synergistic effect, while hybridizing the polyurethane chain segment and enhancing its cross-linking ability with inorganic materials, ultimately improving the wear resistance and flame retardancy of the material.

[0145] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. Halogen-free flame-retardant TPU material suitable for charging pile cables, characterized in that: The invention comprises the following raw material components in parts by weight: 80-100 parts of a cross-linked thermoplastic elastomer, 10-20 parts of a modified filler, 10-20 parts of a flame retardant chain extender, 3-5 parts of a stabilizer, 3-5 parts of an antioxidant, 3-5 parts of an ultraviolet absorber and 3-5 parts of a lubricant; Among them, the preparation method of the cross-linked thermoplastic elastomer is as follows: 8-10 parts of activated thermoplastic elastomer, 3-5 parts of flame retardant chain extender, 0.5-0.8 parts of triethylamine and 40-60 parts of N,N-dimethylformamide are weighed by weight, added into a reactor and stirred, the temperature of the reactor is increased to 80-100°C, the reaction is kept warm for 2-4 hours, and the cross-linked thermoplastic elastomer is obtained by post-treatment.

2. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 1, characterized in that: The preparation method of the activated thermoplastic elastomer comprises the following steps: A1. Add diethylene glycol ether, 1,5-hexadiene-3,4-diol, dibutyltin dilaurate and toluene into a reactor. After the temperature of the reactor is raised to 60-80° C., add toluene-2,6-diisocyanate solution into the reactor and keep the temperature for 2-3 hours. After the reaction is completed, post-process to obtain a modified thermoplastic elastomer. A2. Add the oxidizing liquid and N,N-dimethylformamide into a reactor and stir. After the temperature of the reactor drops to 0-5°C, add the modified thermoplastic elastomer into the reactor and keep the temperature for 1-2 hours. After post-treatment, an activated thermoplastic elastomer is obtained.

3. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 2, characterized in that: In step A1, the amount ratio of diethylene glycol ether, 1,5-hexadiene-3,4-diol, dibutyltin dilaurate toluene and toluene-2,6-diisocyanate solution is 4-5g:8-10g:0.2-0.5g:40-60mL:10-12mL; in step A2, the amount ratio of oxidation solution, N,N-dimethylformamide and modified thermoplastic elastomer is 3-5mL:20-30mL:5-8g.

4. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 1, characterized in that: The preparation method of the flame retardant chain extender comprises the following steps: B1. Add flame retardant monomer, (2-methyl-2-propylene) succinic anhydride, platinum tetrachloride and dimethyl sulfoxide into a reaction kettle, introduce nitrogen protection, raise the temperature of the reaction kettle to 120-140°C, keep the temperature for reaction for 2-4 hours, and post-treat to obtain a reaction precursor; B2. Add the reaction precursor, N,N'-di(2-hydroxyethyl)-1,3-propylenediamine, chlorine trichloride and pyridine into the reaction kettle, raise the temperature of the reaction kettle to 80-100°C, keep the temperature for 2-3h, and post-treat to obtain the modified flame retardant; B3. Add modified flame retardant, epichlorohydrin, sodium carbonate, triethyl borate and ethyl acetate into the reactor, lower the temperature of the reactor to 0-5°C, keep the reaction temperature for 1-2h, and post-treat to obtain flame retardant chain extender.

5. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 4, characterized in that: In step B1, the amount ratio of flame retardant monomer, (2-methyl-2-propylene) succinic anhydride, platinum tetrachloride and dimethyl sulfoxide is 8-10g:4-5g:0.3-0.5g:40-60mL; in step B2, the amount ratio of reaction precursor, N,N'-di(2-hydroxyethyl)-1,3-propylenediamine, chlorine trichloride and pyridine is 8-10g:3-5g:0.3-0.5g:40-60mL; in step B3, the amount ratio of modified flame retardant, epichlorohydrin, sodium carbonate, triethyl borate and ethyl acetate is 8-10g:4-5g:1-2g:0.3-0.5g:40-60mL.

6. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 4, characterized in that: The method for preparing the flame retardant monomer comprises the following steps: C1, adding vinylmethylsilane, trimethylchlorosilane, chlorotristriphenylphosphine rhodium and toluene into a reaction kettle, introducing nitrogen protection, reacting at room temperature for 1-2h, and post-treating to obtain modified silane; C2, adding modified silane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakistriphenylphosphine palladium and dimethyl sulfoxide into a reaction kettle, introducing nitrogen protection, raising the temperature of the reaction kettle to 80-100° C., keeping the temperature for reaction for 1-2 hours, and post-treating to obtain phosphosilane; C3. Add silyl phosphide, ammonium fluoride and dimethyl sulfoxide into a reactor, introduce nitrogen protection, raise the temperature of the reactor to 80-100° C., keep the temperature for reaction for 1-2 hours, and post-treat to obtain a flame retardant monomer.

7. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 6, characterized in that: In step C1, the amount ratio of vinylmethylsilane, trimethylchlorosilane, chlorotristriphenylphosphine rhodium and toluene is 4-6g:3-5g:0.3-0.5g:40-60mL; in step C2, the amount ratio of modified silane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakistriphenylphosphine palladium and dimethyl sulfoxide is 4-6g:8-10g:0.3-0.5g:40-60mL; in step C3, the amount ratio of phosphosilane, ammonium fluoride and dimethyl sulfoxide is 4-6g:1-2g:20-30mL.

8. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 1, characterized in that: The preparation method of the modified filler comprises the following steps: D1. Add magnesium hydroxide and aluminum hydroxide into a grinder, grind and mix evenly, and sieve to obtain a mixed powder; D2. Add flame retardant powder, triethylamine and deionized water into a reactor and stir. After the temperature of the reactor is reduced to 0-5°C, add 3-(2,3-epoxypropoxy)propyltrimethoxysilane into the reactor and keep the temperature for 30-40 minutes. Post-process and obtain the modified filler.

9. The halogen-free flame-retardant TPU material suitable for charging pile cables according to claim 8, characterized in that: In step D1, the dosage ratio of magnesium hydroxide to aluminum hydroxide is 1g:2-3g, and the mesh size of the sieve is 300-600 mesh; in step D2, the stirring rate of the reactor is 80-120rpm, and the dosage ratio of flame retardant powder, triethylamine, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and deionized water is 8-10g:0.3-0.5g:2-3g:40-60mL.

10. The method for preparing the halogen-free flame-retardant TPU material suitable for charging pile cables according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, adding a cross-linked thermoplastic elastomer, a modified filler, a flame retardant chain extender, a stabilizer, an antioxidant, an ultraviolet absorber and a lubricant into a stirring tank, and mixing them evenly to obtain a TPU material precursor; S2, adding the TPU material precursor into a twin-screw extruder, and melt-extrude to obtain the TPU material.

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