Halogen-free flame-retardant, high-heat-insulation, high-strength cable wrapping composite material and preparation method thereof

Abstract

The application discloses a kind of halogen-free flame-retardant, high heat insulation, high strength cable wrapping composite material and preparation method thereof.The cable wrapping composite material is that halogen-free flame-retardant, high heat insulation, high strength coating is coated on glass fiber cloth by coating instrument, and is prepared by heat curing at 80 DEG C.The raw materials of the coating include: thermoplastic polyurethane 80 parts, polydopamine and ZIF-8 double-layer wrapped ammonium polyphosphate 18 parts, polyphosphazene nanoshell wrapped cuprous oxide or polyphosphazene nanoshell wrapped titanium dioxide 2 parts by weight fraction.The application uses polydopamine and ZIF-8 double-layer wrapped ammonium polyphosphate, polyphosphazene nanoshell wrapped cuprous oxide or titanium dioxide as hybrid flame retardant.The halogen-free flame-retardant, high heat insulation, high strength cable wrapping composite material prepared by the application has excellent mechanical properties, and the attached flame-retardant coating can effectively insulate heat, significantly reduce the fire risk of cable, and protect the internal structure of cable.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant and heat insulation material preparation, specifically relating to a halogen-free flame retardant, high heat insulation, and high strength cable wrapping composite material and its preparation method. Background Technology

[0002] In today's era, electricity has become the core energy source supporting the operation of society, and the ability to ensure its stable and efficient transmission is directly related to the stable development of modern society. Cables, as a key carrier of electricity transmission, play an irreplaceable role in various fields. However, while cables bring convenience, they also pose certain dangers. Cable fires caused by high temperatures, aging, and short circuits occur frequently, posing a significant threat to social economy and public safety. Therefore, improving the heat insulation and fire resistance performance of cable materials is an urgent problem to be solved.

[0003] Currently, the use of fire-resistant wrapping tape is one of the main measures to improve the flame-retardant and heat-insulating performance of cables. Fire-resistant wrapping tape not only possesses excellent flame-retardant properties itself, but also covers and protects the cable's insulation layer and conductor, effectively isolating heat and protecting the cable's internal structure. Furthermore, compared to complex built-in flame-retardant materials, the application of fire-resistant wrapping tape is easier to install and maintain, and it can be easily applied to different types of cables, improving the flexibility of production and use, thus leading to its widespread use. In recent years, many scholars have studied it. Sun et al. used fiberglass cloth as a matrix, modified phenolic resin to prepare a coating, and then impregnated the tape with the composite coating to obtain a coarse wrapping tape. The resulting composite material possesses advantages such as low smoke and flame retardancy, and simple processing. However, the inherent brittleness and limited adhesive properties of phenolic resin restrict its application range. Yao et al. prepared a fire-resistant and arc-resistant cable wrapping tape by coating both sides of glass fiber cloth with a fire-resistant and heat-insulating layer and a semi-conductive coating, which can effectively prevent the spread of flames and also has properties such as high temperature resistance, salt resistance, and acid and alkali resistance. However, it still suffers from drawbacks such as high material cost, complex processing, and insufficient mechanical properties, making it unsuitable for large-scale industrial production. Therefore, how to prepare a cable wrapping tape that combines halogen-free flame retardancy, high heat insulation, high strength, and is inexpensive and easy to process is an urgent problem to be solved.

[0004] Thermoplastic polyurethane (TPU), with its excellent mechanical properties, corrosion resistance, and fatigue resistance, has been widely used in industries such as cables, medical devices, hoses, and transportation. Fiberglass cloth is a high-quality inorganic non-metallic material with excellent heat resistance and corrosion resistance; however, it is brittle and easily breaks under impact or compression, and also suffers from defects such as burrs and poor abrasion resistance, further limiting its application. To overcome these shortcomings, a proposed approach is to add flame retardants to liquid TPU and then uniformly coat it onto the surface of fiberglass cloth to prepare a cable wrapping material with excellent flame retardant, heat insulation, and mechanical properties. The current urgent problem is finding a suitable additive.

[0005] Recent studies have shown that the introduction of ammonium polyphosphate can significantly improve the flame retardant and thermal insulation properties of polymers. For example, Cheng et al. found that adding 9% ammonium polyphosphate to epoxy resin reduced the thermal conductivity from 0.1606 W / m·K to 0.0458 W / m·K, while increasing the limiting oxygen index from 19.2% to 26.1%, demonstrating excellent thermal insulation and flame retardant properties. Nie et al. added ammonium polyphosphate to TPU through melt blending, and the peak heat release rate and total heat release of the modified composite material decreased by 87% and 65%, respectively, showing excellent flame retardant properties. However, the poor dispersibility of ammonium polyphosphate leads to a significant decrease in the mechanical properties of the composite material. Zhi et al. used polydopamine and copper to double-coat ammonium polyphosphate, enabling the modified ammonium polyphosphate to be uniformly distributed in the TPU matrix. The composite material prepared by adding 5% polydopamine and copper-coated ammonium polyphosphate showed a 25% and 29% reduction in total heat release rate and total smoke emission rate, respectively, due to the catalytic effect of copper, without a significant decrease in mechanical properties. However, the flame retardant properties of the material were insufficient to meet practical application requirements. This demonstrates that simply modifying the surface or using double-layer coating technology to prepare coated ammonium polyphosphate is unlikely to achieve satisfactory flame retardant effects. Summary of the Invention

[0006] This invention introduces a dual synergistic (synergistic dispersion and synergistic catalysis) effect to enhance the flame retardant properties of the TPU coating, while also endowing the packaging material with excellent mechanical and thermal insulation properties to meet the operational environment requirements of modern society.

[0007] The first objective of this invention is to prepare a halogen-free flame-retardant, high-heat-insulating, and high-strength coating. By adding polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate and polyphosphazene nanoshell encapsulated cuprous oxide / titanium dioxide, the prepared coating can have high strength while imparting excellent flame-retardant and heat-insulating properties to the material.

[0008] The second objective of this invention is to prepare a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material, which is prepared by coating glass fiber cloth with the above-mentioned coating. This can effectively improve the shortcomings of glass fiber cloth, such as brittleness, numerous burrs, and poor wear resistance, so that the cable wrapping material has excellent mechanical properties.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] The first aspect of the present invention provides a halogen-free flame-retardant, high heat-insulating, and high-strength coating, wherein the raw materials of the coating, by weight, include: 80 parts of thermoplastic polyurethane, 18 parts of ammonium polyphosphate double-coated with polydopamine and ZIF-8, 2 parts of cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells, and 60 parts of N,N-dimethylformamide.

[0011] The preparation method of the polydopamine and ZIF-8 double-layer-coated ammonium polyphosphate includes the following steps:

[0012] (1) Ammonium polyphosphate was ultrasonically dispersed in methanol and stirred continuously at room temperature for 30 minutes. Then, 2-methylimidazole and zinc nitrate hexahydrate were added and stirred continuously at room temperature for 3 hours. After centrifugation, washing with anhydrous ethanol, and vacuum drying at 60°C overnight, substance A was obtained.

[0013] (2) Disperse substance A in anhydrous ethanol, add Tris-HCl buffer and polydopamine in sequence, adjust the pH and stir continuously at room temperature for 24 hours. After filtering and washing with anhydrous ethanol, the resulting solution is dried under vacuum at 60°C for 24 hours to obtain polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate.

[0014] The preparation method of cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells includes the following steps: dispersing cuprous oxide or titanium dioxide in acetonitrile, adding 4,4'-diaminodiphenyl ether, triethylamine and hexachlorotriphosphazene in sequence, setting the reaction temperature to 40°C, stirring continuously for 6 hours, centrifuging after reaction, washing with anhydrous ethanol, and vacuum drying at 60°C for 24 hours to obtain cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells.

[0015] The preparation method of the halogen-free flame-retardant, high-heat-insulating, and high-strength coating includes the following steps:

[0016] (1) Weigh out appropriate proportions of thermoplastic polyurethane, polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate, cuprous oxide encapsulated in polyphosphazene nanoshells or titanium dioxide encapsulated in polyphosphazene nanoshells as raw materials.

[0017] (2) Add thermoplastic polyurethane, polydopamine and ZIF-8 double-coated ammonium polyphosphate to N,N-dimethylformamide and stir until dissolved;

[0018] (3) Mix the two solutions obtained in step (2), and add cuprous oxide wrapped in polyphosphazene nanoshells or titanium dioxide wrapped in polyphosphazene nanoshells. After ultrasonic stirring, a halogen-free flame-retardant, high heat-insulating, and high-strength coating is obtained.

[0019] The second aspect of the present invention provides a method for preparing a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material, comprising the following steps: uniformly coating the above-mentioned halogen-free flame-retardant, high-heat-insulating, and high-strength coating onto both sides of a glass fiber cloth using a coating instrument, and then performing a heat curing treatment to shape it, thereby obtaining the halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material.

[0020] The present invention has the following advantages and beneficial effects:

[0021] This invention uses an original method to prepare a coating that combines halogen-free flame retardancy, high heat insulation and mechanical reinforcement properties, and then combines it with glass fiber cloth, effectively combining the advantages of both, with low cost and simple preparation process.

[0022] The polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate and polyphosphazene nanoshell-encapsulated cuprous oxide / titanium dioxide system of this invention achieve simultaneous improvement of the flame retardant, heat insulation and mechanical properties of TPU matrix through a multi-scale synergistic mechanism. Regarding flame retardancy, when the composite material comes into contact with a flame, the modified ammonium polyphosphate can rapidly catalyze the dehydration and cross-linking of the TPU matrix to form an expanded char layer, effectively blocking the transfer of heat and oxygen. The addition of metal oxides further promotes this process. The generated CuO / TiO2 enhances the density of the carbon layer, forming a more continuous barrier. In the gas phase, AZP and PZM release inert gases such as N2, NH3, and CO2 during thermal degradation, diluting the concentration of combustible gases. At the same time, they release PO· and HPO· free radicals, which capture active groups and terminate the combustion chain reaction, thereby endowing the TPU matrix with excellent flame retardant properties. In addition, the addition of hybrid flame retardants can effectively enhance the phonon scattering effect inside the TPU matrix, thereby improving the thermal insulation performance of the composite material. The mechanical reinforcement mechanism comes from the good dispersion of hybrid flame retardants in the matrix and the nano-reinforcement effect, which effectively improves the interfacial compatibility between the TPU matrix and the glass fiber cloth, giving the composite material excellent mechanical properties. Attached Figure Description

[0023] Figure 1 It is a halogen-free, flame-retardant, high-insulation, high-strength cable wrapping composite material with low thermal conductivity.

[0024] Figure 2The results are the vertical combustion test results of Example 1 (TPU / G-APP@ZIF-8@PDA-Cu2O@PZM), Example 2 (TPU / G-APP@ZIF-8@PDA-TiO2@PZM), and Comparative Example 1 (TPU / G);

[0025] Figure 3 The heat release curves of halogen-free flame-retardant, high-insulation, and high-strength cable wrapping composite materials during combustion are shown: (a) heat release rate; (b) total heat release.

[0026] Figure 4 These are the tensile strength and elongation at break data of halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite materials. Detailed Implementation

[0027] The technical solutions of the present invention are described below with reference to specific embodiments. The described embodiments are merely some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0028] A halogen-free flame-retardant, high-heat-insulating, and high-strength coating, wherein the raw materials of the coating, by weight, include: 80 parts of thermoplastic polyurethane, 18 parts of ammonium polyphosphate double-coated with polydopamine and ZIF-8, 2 parts of cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells, and 60 parts of N,N-dimethylformamide.

[0029] The preparation method of the polydopamine and ZIF-8 double-layer-coated ammonium polyphosphate includes the following steps:

[0030] (1) 10 g of ammonium polyphosphate was ultrasonically dispersed in 200 mL of methanol and stirred continuously at room temperature for 30 minutes. Then, 26.27 g of 2-methylimidazole and 11.89 g of zinc nitrate hexahydrate were added to two 150 mL portions of methanol and stirred until dissolved. These were then poured into the ammonium polyphosphate solution and stirred at room temperature for 3 hours. After centrifugation, the mixture was washed with anhydrous ethanol and dried under vacuum at 60 °C overnight to obtain substance A.

[0031] (2) 10 g of substance A was ultrasonically dispersed in 1000 mL of anhydrous ethanol, and then 1.21 g of Tris-HCl buffer (adjusted to pH 8.5 with NaOH) and 1.00 g of polydopamine were added sequentially. The mixture was stirred at room temperature for 24 hours. After the reaction was completed, the mixture was washed three times with anhydrous ethanol and then dried at 60 °C for 24 hours to obtain polydopamine and ZIF-8 bilayer-coated ammonium polyphosphate.

[0032] The preparation method of the cuprous oxide or titanium dioxide encapsulated in the polyphosphazene nanoshell includes the following steps:

[0033] Ten mg of cuprous oxide or titanium dioxide was ultrasonically dispersed in 50 mL of acetonitrile. Then, 40 mg of 4,4'-diaminodiphenyl ether and 3 mL of triethylamine were added to the above solution. Next, 20 mg of hexachlorotriphosphazene was dissolved in 5 mL of acetonitrile and added dropwise to the system over 30 minutes. The mixture was maintained at 40 °C and ultrasonically stirred for 6 hours. After the reaction was complete, the precipitate was collected by centrifugation and washed three times with 20 mL of ethanol. Finally, the precipitate was vacuum dried at 60 °C to obtain cuprous oxide or titanium dioxide nanoshells encapsulated in polyphosphazene nanoshells.

[0034] The preparation method of the halogen-free flame-retardant, high-heat-insulating, and high-strength coating includes the following steps:

[0035] (1) Weigh out appropriate proportions of thermoplastic polyurethane, polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate, cuprous oxide encapsulated in polyphosphazene nanoshells or titanium dioxide encapsulated in polyphosphazene nanoshells as raw materials.

[0036] (2) Add thermoplastic polyurethane, polydopamine and ZIF-8 double-layer coated ammonium polyphosphate to N,N-dimethylformamide respectively, and stir at 80°C until dissolved;

[0037] (3) Mix the two solutions obtained in step (2), and add cuprous oxide wrapped in polyphosphazene nanoshells or titanium dioxide wrapped in polyphosphazene nanoshells. After ultrasonic stirring, a halogen-free flame-retardant, high heat-insulating, and high-strength coating is obtained.

[0038] A method for preparing a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material includes the following steps: uniformly coating the above-mentioned halogen-free flame-retardant, high-heat-insulating, and high-strength coating onto both sides of a glass fiber cloth using a coating instrument, and then performing a heat curing treatment to shape it, thereby obtaining the halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material.

[0039] Example 1

[0040] A method for preparing a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material includes the following steps:

[0041] (1) The raw materials are 80 parts by weight of thermoplastic polyurethane, 18 parts by weight of ammonium polyphosphate double-coated with polydopamine and ZIF-8, and 2 parts by weight of cuprous oxide coated with polyphosphazene nanoshell.

[0042] (2) Add thermoplastic polyurethane to 30 parts by weight of N,N-dimethylformamide, add polydopamine and ZIF-8 double-layer coated ammonium polyphosphate to 30 parts by weight of N,N-dimethylformamide, and stir at 80°C until dissolved.

[0043] (3) Mix the two solutions obtained in step (2), add cuprous oxide wrapped in polyphosphazene nanoshells and stir ultrasonically to obtain a halogen-free flame retardant, high heat insulation and high strength coating.

[0044] (4) Use a coating machine to evenly coat 5g of the above coating onto both sides of a 15cm × 15cm glass fiber cloth, and after heat curing at 80℃, obtain a halogen-free flame-retardant, high heat insulation, and high strength cable wrapping composite material (TPU / G-APP@ZIF-8@PDA-Cu2O@PZM, abbreviated as TPU / G-APZ-CP).

[0045] Example 2

[0046] A method for preparing a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material includes the following steps:

[0047] (1) The raw material group consists of 80 parts by weight of thermoplastic polyurethane, 18 parts by weight of ammonium polyphosphate double-coated with polydopamine and ZIF-8, and 2 parts by weight of titanium dioxide coated with polyphosphazene nanoshell.

[0048] (2) Add thermoplastic polyurethane to 30 parts by weight of N,N-dimethylformamide, add polydopamine and ZIF-8 double-layer coated ammonium polyphosphate to 30 parts by weight of N,N-dimethylformamide, and stir at 80°C until dissolved.

[0049] (3) Mix the two solutions obtained in step (2), add titanium dioxide wrapped in polyphosphazene nanoshells and stir ultrasonically to obtain a halogen-free flame retardant, high heat insulation and high strength coating.

[0050] (4) Use a coating machine to evenly coat 5g of the above coating onto both sides of a 15cm × 15cm glass fiber cloth, and after heat curing at 80℃, obtain a halogen-free flame-retardant, high heat insulation, and high strength cable wrapping composite material (TPU / G-APP@ZIF-8@PDA-TiO2@PZM, abbreviated as TPU / G-APZ-TP).

[0051] Comparative Example 1

[0052] A method for preparing thermoplastic polyurethane / glass fiber cloth cable wrapping tape includes the following steps:

[0053] (1) Using 100 parts by weight of thermoplastic polyurethane as raw material;

[0054] (2) Add thermoplastic polyurethane to 60 parts by weight of N,N-dimethylformamide and stir at 80°C until dissolved to obtain unmodified coating;

[0055] (3) Use a coating machine to evenly coat 5g of the above coating onto both sides of a 15cm × 15cm glass fiber cloth, and then heat-cur it at 80℃ to obtain cable wrapping composite material (TPU / G).

[0056] Comparative Example 2

[0057] A method for preparing a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material includes the following steps:

[0058] (1) The raw materials consist of 80 parts by weight of thermoplastic polyurethane and 20 parts by weight of ammonium polyphosphate;

[0059] (2) Add thermoplastic polyurethane to 30 parts by weight of N,N-dimethylformamide and ammonium polyphosphate to 30 parts by weight of N,N-dimethylformamide, and stir at 80°C until dissolved;

[0060] (3) After mixing and stirring the two solutions obtained in step (2), a halogen-free flame retardant, high heat insulation, and high strength coating is obtained;

[0061] (4) Use a coating machine to evenly coat 5g of the above coating onto both sides of a 15cm × 15cm glass fiber cloth, and after heat curing at 80℃, obtain a halogen-free flame-retardant, high heat insulation, and high strength cable wrapping composite material (TPU / G-APP, abbreviated as TPU / GA).

[0062] Comparative Example 3

[0063] A method for preparing a halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material includes the following steps:

[0064] (1) The raw material group consists of 80 parts by weight of thermoplastic polyurethane, 20 parts by weight of polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate;

[0065] (2) Add thermoplastic polyurethane to 30 parts by weight of N,N-dimethylformamide, add polydopamine and ZIF-8 double-layer coated ammonium polyphosphate to 30 parts by weight of N,N-dimethylformamide, and stir at 80°C until dissolved.

[0066] (3) After mixing and stirring the two solutions obtained in step (2), a halogen-free flame retardant, high heat insulation, and high strength coating is obtained;

[0067] (4) Use a coating machine to evenly coat 5g of the above coating onto both sides of a 15cm × 15cm glass fiber cloth, and after heat curing at 80℃, obtain a halogen-free flame-retardant, high heat insulation, and high strength cable wrapping composite material (TPU / G-APP@ZIF-8@PDA, abbreviated as TPU / G-APZ).

[0068] The cable wrapping composite materials obtained in Examples 1 and 2, and Comparative Examples 1, 2, and 3 were tested using a thermal conductivity meter. The experimental results are shown in [Figure 1]. Figure 1 The test results were obtained by using a vertical combustion test apparatus. Figure 2 Combustion tests were conducted using a cone calorimeter under conditions of 35 kW / m³. 2 The experimental results are shown in Figure 3 Tensile strength was tested using the constant-rate tensile method under the following conditions: 20 mm / min. The test results are shown below. Figure 4 .

[0069] Figure 1 The thermal conductivity test results of glass fiber cloth (GFC) and cable wrapping composites are presented. The unmodified glass fiber cloth exhibits a high thermal conductivity of 49.9 mW / m·K. After coating with pure thermoplastic polyurethane, the thermal conductivity of the composite decreased to 33.9 mW / m·K, and further decreased to 28.7 mW / m·K after the addition of ammonium polyphosphate. Furthermore, by introducing ammonium polyphosphate double-layered with polydopamine and ZIF-8, and cuprous oxide / titanium dioxide encapsulated in polyphosphazene nanoshells, the thermal conductivity of the material decreased to 20.9 mW / m·K and 20.8 mW / m·K, respectively, representing reductions of 58% and 58.3% compared to pure glass fiber cloth. This result demonstrates that the addition of the aforementioned flame retardants significantly improves the thermal insulation performance of the composite.

[0070] The flame-retardant properties of the material were evaluated using vertical burning tests and cone calorimetry. Figure 2 The results of vertical burning tests on Examples 1 and 2 and Comparative Example 1 are presented. The results show that the pure TPU coating on the surface of Comparative Example 1 was completely burned after the test, while the burn lengths of the coatings in Examples 1 and 2 after the test were 6.8 cm and 7.6 cm, respectively, indicating that the added flame retardant imparts excellent flame-retardant properties to the TPU coating. Furthermore, the flame-retardant properties of the materials were further evaluated using a cone calorimeter. Figure 3 As shown in Table 1, the PHRR of Comparative Example 1 is 227 kW / m². 2 This poses a high fire risk. After adding 20 wt% ADP, the PHRR of Comparative Example 2 sample decreased to 116 kW / m³. 2 After surface modification of the APP, the power output of Comparative Example 3 sample was further reduced to 113 kW / m². 2 However, after the addition of metal oxides, the PHRR of Examples 1 and 2 increased by 6.6% and 8.9% respectively compared to Comparative Example 3. This may be due to Cu2O and TiO2 catalyzing the early decomposition of AZP and TPU, leading to intensified local combustion. THR data showed that Examples 1 and 2 had the lowest THR (12.9 MJ / m³, respectively). 2 and 12.7 MJ / m2 This is attributed to the synergistic effect of AZP and metal oxides, which improves the quality of the char layer, enhances the heat barrier effect, and thus reduces the total heat release. The above results indicate that hybrid flame retardants provide excellent flame retardant properties for TPU coatings.

[0071] Table 1 CCT data of composite materials

[0072]

[0073] pass Figure 4 It can be seen that the tensile strength of pure glass fiber cloth is only 62.0 MPa, while the tensile strength of the composite material coated with thermoplastic polyurethane is significantly increased to 170.6 MPa, an increase of 175.2% year-on-year. For the material with added ammonium polyphosphate, its tensile strength and elongation at break are lower than those of the pure TPU-coated sample, which may be due to the poor dispersibility of ammonium polyphosphate. However, the tensile strengths of Examples 1 and 2 reached 202.0 MPa and 213.7 MPa, respectively, indicating that these flame retardants can be uniformly distributed in the material, and the modified coating and glass fiber cloth exhibit better interfacial compatibility, thereby effectively improving the mechanical properties of the composite material.

[0074] The foregoing provides a detailed description of the halogen-free flame-retardant, high-heat-insulating, and high-strength cable wrapping composite material and its preparation method provided by this invention. Specific examples illustrate the preparation process and application prospects of this invention, facilitating understanding of the method and core concepts. It should be noted that those skilled in the art can make various modifications and improvements to this invention, and these modifications and improvements should also fall within the scope of protection of the claims of this invention.

Claims

1. A halogen-free flame-retardant, high-heat-insulating, and high-strength coating, characterized in that, The raw materials of the coating, by weight, include: 80 parts of thermoplastic polyurethane, 18 parts of ammonium polyphosphate double-coated with polydopamine and ZIF-8, 2 parts of cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells, and 60 parts of N,N-dimethylformamide. The preparation method of the polydopamine and ZIF-8 double-layer coated ammonium polyphosphate includes the following steps: 1) Ammonium polyphosphate was ultrasonically dispersed in methanol and stirred continuously at room temperature for 30 minutes. Then, 2-methylimidazole and zinc nitrate hexahydrate were added and stirred continuously at room temperature for 3 hours. After centrifugation, washing with anhydrous ethanol, and vacuum drying at 60°C overnight, substance A was obtained. 2) Disperse substance A in anhydrous ethanol, add Tris-HCl buffer and polydopamine in sequence, adjust the pH and stir continuously at room temperature for 24 hours. After filtration and washing with anhydrous ethanol, the resulting solution is vacuum dried at 60°C for 24 hours to obtain polydopamine and ZIF-8 double-layer coated ammonium polyphosphate. The preparation method of cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells includes the following steps: dispersing cuprous oxide or titanium dioxide in acetonitrile, adding 4,4'-diaminodiphenyl ether, triethylamine and hexachlorotriphosphazene in sequence, setting the reaction temperature to 40°C, stirring continuously for 6 hours, centrifuging after reaction, washing with anhydrous ethanol, and vacuum drying at 60°C for 24 hours to obtain cuprous oxide or titanium dioxide encapsulated in polyphosphazene nanoshells; The preparation method of the halogen-free flame-retardant, high-heat-insulating, and high-strength coating includes the following steps: (1) Weigh out thermoplastic polyurethane, polydopamine and ZIF-8 double-layer encapsulated ammonium polyphosphate, cuprous oxide encapsulated in polyphosphazene nanoshell or titanium dioxide encapsulated in polyphosphazene nanoshell according to the proportion. (2) Add thermoplastic polyurethane, polydopamine and ZIF-8 double-coated ammonium polyphosphate to N,N-dimethylformamide and stir until dissolved; (3) Mix the two solutions obtained in step (2), and add cuprous oxide wrapped in polyphosphazene nanoshells or titanium dioxide wrapped in polyphosphazene nanoshells. After ultrasonic stirring, a halogen-free flame-retardant, high heat-insulating, and high-strength coating is obtained.

2. A method for preparing cable sheathing composite material using the halogen-free flame-retardant, high-heat-insulating, and high-strength coating as described in claim 1, characterized in that: A halogen-free flame-retardant, high-heat-insulating, and high-strength coating is applied to fiberglass cloth using a coating machine and then heat-cured at 80°C.

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