High-temperature-resistant flame-retardant cable and preparation method thereof

Abstract

The invention relates to the technical field of cables, and provides a high-temperature-resistant flame-retardant cable and a preparation method thereof. The high-temperature-resistant flame-retardant cable comprises a conductor and a flame-retardant outer sheath, the flame-retardant outer sheath is prepared from the following raw materials in parts by weight: 40 to 50 parts of linear low-density polyethylene, 35 to 45 parts of ethylene-vinyl acetate copolymer, 10 to 15 parts of ethylene propylene diene monomer, 15 to 18 parts of modified aluminum hydroxide, 10 to 14 parts of modified magnesium hydroxide, 5 to 8 parts of polyethylene grafted maleic anhydride, 5 to 8 parts of microencapsulated red phosphorus, 2 to 3 parts of silane coupling agent and 0.8 to 1 part of antioxidant. The composite material is prepared from the following components in parts by weight: 0.5-1 part of a light stabilizer, 0.5-1 part of calcium stearate, 0.8-1 part of polyethylene wax and 0.5-0.9 part of carbon nanotubes. According to the cable prepared in the invention, the performance stability of an existing high-temperature-resistant material in a high-temperature environment is improved, and the problems of softening, melting and the like of the cable are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a high-temperature resistant flame-retardant cable and a preparation method thereof. Background Art

[0002] Cables, as crucial carriers for power and information transmission, are widely used in various fields. High-temperature-resistant materials maintain their physical and chemical properties at high temperatures, ensuring the cable's electrical performance is not affected. Flame-retardant materials prevent the spread of flames and the transfer of heat by forming a carbonized layer and releasing flame-retardant gases during combustion.

[0003] Although existing high-temperature resistant materials can withstand high temperatures to a certain extent, in some high-temperature environments, the performance of some materials will drop sharply, and problems such as softening and melting will occur, resulting in the cable not being able to work properly. Although some flame-retardant materials can form a carbonized layer when burning, the strength and stability of the carbonized layer are insufficient, and it is easy to crack or fall off, and it cannot effectively prevent the spread of flames. In addition, although some flame-retardant materials can form a carbonized layer when burning, the strength and stability of the carbonized layer are insufficient, and it is easy to crack or fall off, and it cannot effectively prevent the spread of flames. In order to solve the above-mentioned technical problems, the present invention proposes a new high-temperature resistant flame-retardant cable and a preparation method thereof. Summary of the Invention

[0004] The present invention proposes a high-temperature resistant flame-retardant cable and a preparation method thereof, which improves the performance stability of existing high-temperature resistant materials in high-temperature environments, avoids problems such as softening and melting, and ensures the normal operation of the cable; improves the strength and stability of the carbonized layer of existing flame-retardant materials during combustion, prevents it from cracking or falling off, and more effectively prevents the spread of flames.

[0005] The technical solutions of the present invention are as follows: In the first aspect, the present invention proposes a high-temperature resistant flame-retardant cable, comprising a conductor and a flame-retardant outer sheath, wherein the flame-retardant outer sheath is composed of the following raw materials in parts by weight: 40-50 parts of linear low-density polyethylene, 35-45 parts of ethylene-vinyl acetate copolymer, 10-15 parts of EPDM rubber, 15-18 parts of modified aluminum hydroxide, 10-14 parts of modified magnesium hydroxide, 5-8 parts of polyethylene grafted maleic anhydride, 5-8 parts of microencapsulated red phosphorus, 2-3 parts of silane coupling agent, 0.8-1 part of antioxidant, 0.5-1 part of light stabilizer, 0.5-1 part of calcium stearate, 0.8-1 part of polyethylene wax, and 0.5-0.9 part of carbon nanotubes.

[0006] As a further technical solution, the preparation method of the modified aluminum hydroxide comprises: vacuum drying aluminum hydroxide powder at 100-120℃ for 2-4h; mixing ethanol and water uniformly, slowly adding silane coupling agent A-151, stirring at room temperature to obtain a hydrolysis solution, dispersing the dried aluminum hydroxide powder in the hydrolysis solution, reacting at a temperature of 50-60℃ and a speed of 200-300 rpm for 10-12h, and obtaining the modified aluminum hydroxide after centrifugal drying.

[0007] As a further technical solution, the weight ratio of the dried aluminum hydroxide, ethanol, water and silane coupling agent A-151 is 10g:100-150mL:50-100mL:0.3-0.5g.

[0008] As a further technical solution, the preparation method of the modified magnesium hydroxide comprises: vacuum drying magnesium hydroxide powder at 100-120℃ for 2-4h, adding silane coupling agent Si-69 into anhydrous ethanol, adding acetic acid / water mixture to adjust pH to 5 to obtain Si-69 hydrolysis solution; dispersing the dried magnesium hydroxide powder in the Si-69 hydrolysis solution, reacting at a temperature of 60-70℃ for 8-10h, and obtaining the modified aluminum hydroxide after centrifugal drying.

[0009] As a further technical solution, the weight ratio of the dried magnesium hydroxide, ethanol and silane coupling agent Si-69 is 10g:180-220mL:0.4-0.6g.

[0010] As a further technical solution, the preparation method of the microencapsulated red phosphorus comprises: mixing formaldehyde and water, stirring at a speed of 200±20rpm, heating the water bath to 50±2℃, adding NaOH aqueous solution to adjust pH to 8.8±0.2, adding melamine to heat to 85±2℃ at a rate of 2℃ / min, and reacting for 30-50min to prepare a prepolymer; mixing red phosphorus and antimony trioxide, adding water to grind, and then heating to 90-98℃ for azeotropic distillation for 1.5-2.5h to obtain a mixed system; slowly adding the prepolymer to the mixed system, adding hydrochloric acid to adjust pH to 3-5, stirring and reacting, and then centrifuging, washing with water, and drying to obtain the microencapsulated red phosphorus.

[0011] As a further technical solution, the weight ratio of the formaldehyde, water and melamine is 90-110:300-340:120-130; and the weight ratio of the red phosphorus, antimony trioxide and water is 50:20-30:180-220.

[0012] As a further technical solution, the stirring reaction is carried out at a temperature of 80-90℃ and a speed of 300-400 rpm for 50-70min.

[0013] As a further technical solution, the antioxidant includes at least one of antioxidant 1010, antioxidant 1076 and antioxidant 168; the light stabilizer includes light stabilizer 770 and / or light stabilizer 944.

[0014] In the second aspect, the present invention proposes a method for preparing a high-temperature resistant flame-retardant cable, the steps comprising: weighing raw materials according to the formula, stirring and mixing in a high-speed mixer at 40-50°C and 600-800rpm for 20-30 minutes; melting through a twin-screw extruder, and extruding a coated conductor at 175-185°C to form a high-temperature resistant flame-retardant cable.

[0015] The working principle and beneficial effects of the present invention are: The present invention uses a specific modification method to surface-treat aluminum hydroxide and magnesium hydroxide, significantly improving their dispersibility and interfacial bonding strength in the polymer matrix. The modified aluminum hydroxide is surface-treated with silane coupling agent A-151, while the modified magnesium hydroxide is modified with silane coupling agent Si-69. As inorganic flame retardants, aluminum hydroxide and magnesium hydroxide can decompose and absorb heat at high temperatures. The decomposition reaction absorbs a large amount of heat, reduces the surface temperature of the material, and releases non-combustible gases such as water vapor. These decomposition products migrate to the surface of the material and interact with the polymer decomposition products to promote the dehydration and carbonization of the polymer to form a carbonized layer. The modified aluminum hydroxide and magnesium hydroxide have enhanced interfacial bonding with the polymer matrix, making the bonding between the carbonized layer and the matrix tighter, and the formed carbonized layer is more dense and stable.

[0016] Through modification, the surface properties of aluminum hydroxide and magnesium hydroxide are improved, enabling better compatibility with the polymer matrix and forming a uniform dispersion system. This uniform dispersion not only increases the utilization rate of the flame retardant but also enhances the interfacial bonding strength within the material, helping to form a denser carbonized layer during combustion, thereby more effectively preventing the spread of flames. Furthermore, the synergistic effect of the modified aluminum hydroxide and magnesium hydroxide enables the material to maintain better thermal stability and mechanical properties at high temperatures, avoiding problems such as softening and melting. Furthermore, the dense carbonized layer prevents the escape of smoke, further reducing smoke emissions.

[0017] The present invention uses microencapsulation technology to coat red phosphorus and simultaneously introduces antimony trioxide as a synergist to create a dual flame retardant system. During the combustion process, the shell of the microencapsulated red phosphorus ruptures due to heat, releasing the red phosphorus. Red phosphorus reacts with oxygen at high temperatures to produce phosphorus-containing compounds such as phosphoric acid and metaphosphoric acid. These compounds have a strong dehydrating effect and can promote the dehydration and carbonization of the polymer, forming a carbonized layer. Antimony trioxide reacts with red phosphorus to produce compounds such as antimony oxide and antimony phosphate. These compounds can fill the pores of the carbonized layer, further improving the strength and stability of the carbonized layer, making the carbonized layer more dense and effectively preventing the transfer of heat and oxygen. Antimony trioxide sublimates at high temperatures, absorbing heat and lowering the surface temperature of the material. Its sublimation products can dilute combustible gases and inhibit the combustion reaction. At the same time, the compounds generated by the reaction of antimony trioxide and red phosphorus can capture free radicals, such as hydrogen radicals and hydroxyl radicals, in the gas phase, terminating the combustion chain reaction, thereby exerting a flame retardant effect in the gas phase.

[0018] Furthermore, the oxides produced by the decomposition of modified aluminum hydroxide and magnesium hydroxide interact with the compounds formed by the reaction of microencapsulated red phosphorus / antimony trioxide to form a more complex and dense carbonized layer structure. The oxides of the modified aluminum hydroxide / magnesium hydroxide provide a skeletal support for the carbonized layer, while the compounds formed by the reaction of microencapsulated red phosphorus / antimony trioxide fill the pores of the framework, enhancing the strength and stability of the carbonized layer. This synergistic effect enables the carbonized layer to better withstand the impact of flames and heat, effectively preventing flame spread. The modified aluminum hydroxide / magnesium hydroxide and microencapsulated red phosphorus / antimony trioxide mutually promote the carbonization reaction during combustion. The heat and products generated by the decomposition of aluminum hydroxide / magnesium hydroxide provide conditions for the oxidation reaction of red phosphorus, accelerating its carbonization. The carbonized layer formed by the carbonization of red phosphorus provides attachment points for the decomposition products of aluminum hydroxide / magnesium, promoting their further participation in the formation of the carbonized layer. This synergistic effect improves the rate and quality of carbonization, enabling the material to form an effective carbonized layer more quickly during combustion.

[0019] Antimony trioxide acts as a flame retardant in the gas phase, inhibiting the combustion reaction and reducing the generation of combustible gases, thereby reducing the combustion intensity on the material surface. This creates a more favorable environment for the formation of a condensed-phase carbonized layer, enabling it to form and develop under relatively mild conditions, improving its quality and stability. The dense condensed-phase carbonized layer effectively blocks the transfer of heat and oxygen, reducing the contact between combustible gases in the gas phase and oxygen, thereby enhancing the gas-phase flame retardant effect. Furthermore, the carbonized layer can adsorb and immobilize some free radicals and combustion products in the gas phase, further inhibiting the combustion reaction.

[0020] In summary, modified aluminum hydroxide / magnesium and microencapsulated red phosphorus / antimony trioxide successfully formed a dual flame retardant system through carbonization and smoke suppression. They cooperated with each other in the condensed phase and gas phase, optimized the carbonization layer structure, improved the carbonization rate and quality, enhanced the gas phase flame retardant effect, and improved the dispersion and compatibility of the components, thereby achieving synergistic efficiency and significantly improving the flame retardant properties of high temperature resistant flame retardant cables. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] It should be noted that the linear low-density polyethylene in the present invention, CAS No.: 9002-88-4, MDL No.: MFCD00084423, Article No.: L909897, was purchased from Maclean Reagent; ethylene-vinyl acetate copolymer, CAS No.: 24937-78-8, MDL No.: MFCD00133996, Article No.: P815474, was purchased from Maclean Reagent; EPDM rubber was purchased from ExxonMobil Chemical Co., Ltd., USA, model 2504; polyethylene grafted maleic anhydride was purchased from Shanghai Jingzhengfeng Chemical Additive Co., Ltd., model GR202; polyethylene wax was purchased from Qingdao Haihao Chemical Co., Ltd., model H100.

[0023] Example 1 This embodiment provides a high-temperature resistant flame-retardant cable, including a conductor and a flame-retardant outer sheath. The flame-retardant outer sheath is composed of the following raw materials in parts by weight: 45 parts of linear low-density polyethylene, 40 parts of ethylene-vinyl acetate copolymer, 12 parts of EPDM rubber, 16 parts of modified aluminum hydroxide, 12 parts of modified magnesium hydroxide, 6 parts of polyethylene grafted maleic anhydride, 7 parts of microencapsulated red phosphorus, 2.5 parts of silane coupling agent KH550, 0.9 part of antioxidant, 0.8 part of light stabilizer, 0.7 part of calcium stearate, 0.9 part of polyethylene wax, and 0.7 part of carbon nanotubes.

[0024] The preparation method of modified aluminum hydroxide includes: vacuum drying aluminum hydroxide powder at 110°C for 3 hours; taking 120mL of ethanol and 8mL of water and mixing them evenly, slowly adding 0.4g of silane coupling agent A-151 and stirring at room temperature to obtain a hydrolyzate, dispersing 10g of the dried aluminum hydroxide powder in the hydrolyzate, reacting at a temperature of 55°C and 250 rpm for 11 hours, centrifuging, washing with anhydrous ethanol three times, and vacuum drying at 70°C for 8 hours to obtain modified aluminum hydroxide; The preparation method of modified magnesium hydroxide includes: vacuum drying magnesium hydroxide powder at 110°C for 3 hours, adding 0.5g of silane coupling agent Si-69 to 200mL of anhydrous ethanol, and dropwise adding a small amount of a 1:1 weight ratio acetic acid / water mixture to adjust the pH to 5 to obtain a Si-69 hydrolyzate; dispersing 10g of the dried magnesium hydroxide powder in the Si-69 hydrolyzate, reacting at a temperature of 65°C for 10 hours, centrifuging and separating the solid, washing with ethanol three times, vacuum drying at 70°C for 11 hours, and grinding to obtain modified magnesium hydroxide; The preparation method of microencapsulated red phosphorus includes: mixing 100g of formaldehyde and 320g of water, stirring at a rate of 200rpm, heating in a water bath to 50°C, adding a 10% by mass NaOH aqueous solution, adjusting the pH to 8.8, adding 125g of melamine, heating at a rate of 2°C / min to 85°C, and reacting at this temperature for 40min to prepare a prepolymer; mixing 50g of red phosphorus and 25g of antimony trioxide, adding 200g of water, grinding, and then azeotropically co-existing at 94°C for 2h to obtain a mixed system; slowly adding the prepolymer to the mixed system, adding hydrochloric acid to adjust the pH to 4, stirring at 85°C and 350rpm for 60min, and then centrifuging, washing with water, and drying to obtain the product; Among them, the antioxidant is antioxidant 1010; the light stabilizer is light stabilizer 770; The preparation method of a high-temperature resistant flame-retardant cable comprises the following steps: weighing raw materials according to a formula, stirring and mixing them in a high-speed mixer at 45°C and 700 rpm for 25 minutes; melting them through a twin-screw extruder, and extruding a coated conductor at 180°C to form a high-temperature resistant flame-retardant cable.

[0025] Example 2 This embodiment provides a high-temperature resistant flame-retardant cable, including a conductor and a flame-retardant outer sheath. The flame-retardant outer sheath is composed of the following raw materials in parts by weight: 40 parts of linear low-density polyethylene, 35 parts of ethylene-vinyl acetate copolymer, 10 parts of EPDM rubber, 15 parts of modified aluminum hydroxide, 10 parts of modified magnesium hydroxide, 5 parts of polyethylene grafted maleic anhydride, 5 parts of microencapsulated red phosphorus, 2 parts of silane coupling agent KH550, 0.8 parts of antioxidant, 0.5 parts of light stabilizer, 0.5 parts of calcium stearate, 0.8 parts of polyethylene wax, and 0.5 parts of carbon nanotubes.

[0026] The preparation method of modified aluminum hydroxide includes: vacuum drying aluminum hydroxide powder at 100°C for 2 hours; taking 100 mL of ethanol and 50 mL of water and mixing them evenly, slowly adding 0.3 g of silane coupling agent A-151 and stirring at room temperature to obtain a hydrolyzate, dispersing 10 g of the dried aluminum hydroxide powder in the hydrolyzate, reacting at a temperature of 50°C and 200 rpm for 10 hours, centrifuging, washing with anhydrous ethanol three times, and vacuum drying at 60°C for 6 hours to obtain modified aluminum hydroxide; The preparation method of the modified magnesium hydroxide comprises the following steps: vacuum drying magnesium hydroxide powder at 100 DEG C for 2 hours, adding 0.4g silane coupling agent Si-69 into 180mL anhydrous ethanol, adding a small amount of 1:1 weight ratio acetic acid / water mixture to adjust pH to 5 to obtain Si-69 hydrolyzate; dispersing 10g dried magnesium hydroxide powder into the Si-69 hydrolyzate, reacting at 60 DEG C for 8 hours, centrifugally separating the solid, washing with ethanol for 3 times, and vacuum drying at 60 DEG C for 10 hours to obtain the modified magnesium hydroxide; The preparation method of the microencapsulated red phosphorus comprises the following steps: mixing 90g formaldehyde and 300g water, stirring at a speed of 200rpm, heating the water to 50 DEG C in a water bath, adding 10% mass fraction NaOH aqueous solution to adjust pH to 8.8, adding 120g melamine, heating to 85 DEG C at a speed of 2 DEG C / min, and keeping the temperature constant for 30min to prepare a prepolymer; mixing 50g red phosphorus and 20g antimony sesquioxide, grinding with 180g water, and then constant boiling at 90 DEG C for 1.5h to obtain a mixed system; slowly adding the prepolymer into the mixed system, adding hydrochloric acid to adjust pH to 3, stirring at 80 DEG C and 300rpm for 50min, and then centrifuging, washing with water, and drying to obtain the microencapsulated red phosphorus. The antioxidant is antioxidant 1076, and the light stabilizer is light stabilizer 944. The preparation method of the high-temperature-resistant flame-retardant cable comprises the following steps: weighing raw materials according to a formula, stirring and mixing in a high-speed mixer at 40 DEG C and 600rpm for 20min, melting through a double-screw extruder, and extruding a conductor to form the high-temperature-resistant flame-retardant cable at 175 DEG C.

[0027] Example 3 The high-temperature-resistant flame-retardant cable comprises a conductor and a flame-retardant outer sheath, and the flame-retardant outer sheath is composed of the following raw materials in parts by weight: linear low-density polyethylene 50 parts, ethylene-vinyl acetate copolymer 45 parts, ethylene-propylene-diene rubber 15 parts, modified aluminum hydroxide 18 parts, modified magnesium hydroxide 14 parts, polyethylene grafted maleic anhydride 8 parts, microencapsulated red phosphorus 8 parts, silane coupling agent KH550 3 parts, antioxidant 1 part, light stabilizer 1 part, calcium stearate 1 part, polyethylene wax 1 part, and carbon nanotube 0.9 part.

[0028] The preparation method of the modified aluminum hydroxide comprises the following steps: vacuum drying aluminum hydroxide powder at 120 DEG C for 4 hours; mixing 150mL ethanol and 100mL water uniformly, slowly adding 0.5g silane coupling agent A-151 to obtain a hydrolyzate under stirring at room temperature, dispersing 10g dried aluminum hydroxide powder into the hydrolyzate, reacting at 60 DEG C and 300rpm for 12 hours, centrifuging, washing with anhydrous ethanol for 3 times, and vacuum drying at 80 DEG C for 12 hours to obtain the modified aluminum hydroxide. The preparation method of modified magnesium hydroxide includes: vacuum drying magnesium hydroxide powder at 120°C for 4 hours, adding 0.6g of silane coupling agent Si-69 to 220mL of anhydrous ethanol, and dropwise adding a small amount of a 1:1 weight ratio acetic acid / water mixture to adjust the pH to 5 to obtain a Si-69 hydrolyzate; dispersing 10g of the dried magnesium hydroxide powder in the Si-69 hydrolyzate, reacting at a temperature of 70°C for 10 hours, centrifuging and separating the solid, washing with ethanol three times, vacuum drying at 80°C for 12 hours, and grinding to obtain modified magnesium hydroxide; The preparation method of microencapsulated red phosphorus includes: mixing 110g of formaldehyde and 340g of water, stirring at a rate of 200rpm, heating the mixture in a water bath to 50°C, adding a 10% by mass NaOH aqueous solution, adjusting the pH to 8.8, adding 130g of melamine, heating the mixture at a rate of 2°C / min to 85°C, and reacting the mixture for 50min to obtain a prepolymer; mixing 50g of red phosphorus with 30g of antimony trioxide, adding 220g of water, grinding the mixture, and then azeotropically reacting the mixture at 98°C for 2.5h to obtain a mixed system; slowly adding the prepolymer to the mixed system, adjusting the pH to 5 with hydrochloric acid, reacting the mixture at 90°C and 400rpm with stirring for 70min, and then centrifuging, washing with water, and drying the mixture to obtain the microencapsulated red phosphorus. Among them, the antioxidant is antioxidant 168; the light stabilizer is light stabilizer 770; The preparation method of a high-temperature resistant flame-retardant cable comprises the following steps: weighing raw materials according to a formula, stirring and mixing in a high-speed mixer at 50°C and 800 rpm for 30 minutes; melting through a twin-screw extruder, and extruding a coated conductor at 185°C to form a high-temperature resistant flame-retardant cable.

[0029] Example 4 The present embodiment provides a high-temperature resistant flame-retardant cable, including a conductor and a flame-retardant outer sheath. The flame-retardant outer sheath is composed of the following raw materials in parts by weight: 40 parts of linear low-density polyethylene, 45 parts of ethylene-vinyl acetate copolymer, 10 parts of EPDM rubber, 18 parts of modified aluminum hydroxide, 10 parts of modified magnesium hydroxide, 8 parts of polyethylene grafted maleic anhydride, 5 parts of microencapsulated red phosphorus, 3 parts of silane coupling agent KH550, 0.8 parts of antioxidant, 1 part of light stabilizer, 0.5 parts of calcium stearate, 1 part of polyethylene wax, and 0.5 parts of carbon nanotubes.

[0030] The preparation method of modified aluminum hydroxide includes: vacuum drying aluminum hydroxide powder at 100°C for 4 hours; taking 100 mL of ethanol and 100 mL of water, mixing them evenly, slowly adding 0.3 g of silane coupling agent A-151, stirring at room temperature to obtain a hydrolyzate, dispersing 10 g of the dried aluminum hydroxide powder in the hydrolyzate, reacting at a temperature of 60°C and 200 rpm for 12 hours, centrifuging, washing with anhydrous ethanol three times, and vacuum drying at 60°C for 12 hours to obtain modified aluminum hydroxide; The preparation method of modified magnesium hydroxide includes: vacuum drying magnesium hydroxide powder at 100°C for 4 hours, adding 0.4g of silane coupling agent Si-69 to 220mL of anhydrous ethanol, and adding a small amount of a 1:1 weight ratio acetic acid / water mixture to adjust the pH to 5 to obtain a Si-69 hydrolyzate; dispersing 10g of the dried magnesium hydroxide powder in the Si-69 hydrolyzate, reacting at a temperature of 60°C for 10 hours, centrifuging and separating the solid, washing with ethanol three times, vacuum drying at 60°C for 12 hours, and grinding to obtain modified magnesium hydroxide; The preparation method of microencapsulated red phosphorus includes: mixing 90g of formaldehyde and 340g of water, stirring at a rate of 200rpm, heating the water bath to 50°C, adding a 10% by mass NaOH aqueous solution, adjusting the pH to 8.8, adding 120g of melamine, heating the mixture to 85°C at a rate of 2°C / min, and reacting the mixture at a constant temperature for 50min to obtain a prepolymer; mixing 50g of red phosphorus with 20g of antimony trioxide, adding 220g of water, grinding the mixture, and then azeotropically reacting the mixture at a constant temperature of 90°C for 2.5h to obtain a mixed system; slowly adding the prepolymer to the mixed system, adding hydrochloric acid to adjust the pH to 3, stirring the mixture at 90°C and 300rpm for 70min, and then centrifuging, washing with water, and drying the mixture to obtain the microencapsulated red phosphorus. Among them, the antioxidant is antioxidant 1010; the light stabilizer package is light stabilizer 944; The preparation method of a high-temperature resistant flame-retardant cable comprises the following steps: weighing raw materials according to a formula, stirring and mixing them in a high-speed mixer at 40°C and 800 rpm for 20 minutes; melting them through a twin-screw extruder, and extruding a coated conductor at 185°C to form a high-temperature resistant flame-retardant cable.

[0031] Comparative Example 1 In this comparative example, the modified aluminum hydroxide was replaced by unmodified aluminum hydroxide, and untreated aluminum hydroxide powder was directly used. The rest was the same as in comparative example 1, and the preparation steps were the same as in comparative example 1.

[0032] Comparative Example 2 No modified aluminum hydroxide was added in this comparative example. The rest was the same as in comparative example 1, and the preparation steps were the same as in comparative example 1.

[0033] Comparative Example 3 In this comparative example, the modified magnesium hydroxide was replaced by unmodified magnesium hydroxide, and untreated magnesium hydroxide powder was directly used. The rest was the same as in comparative example 1, and the preparation steps were the same as in comparative example 1.

[0034] Comparative Example 4 In this comparative example, no modified magnesium hydroxide was added, and the rest was the same as in comparative example 1, and the preparation steps were the same as in comparative example 1.

[0035] Comparative Example 5 In this comparative example, no antimony trioxide was added during the preparation of microencapsulated red phosphorus. The rest of the preparation was the same as in comparative example 1, and the preparation steps were the same as in comparative example 1.

[0036] Comparative Example 6 In this comparative example, the microencapsulated red phosphorus was replaced with red phosphorus of equal mass, and the rest of the preparation steps were the same as those in comparative example 1.

[0037] Comparative Example 7 In this comparative example, no microencapsulated red phosphorus was added. The rest of the preparation process was the same as in comparative example 1.

[0038] Test Example 1: The high-temperature resistant flame-retardant cables prepared in Examples 1-4 and Comparative Examples 1-7 were subjected to the following tests: Fire resistance test: refer to GB / T19216.21-2003 "Line integrity test for electric or optical cables under flame conditions" for testing, and place the cable sample in a 1000℃ flame for 2 hours; Oxygen Index (LOI) test: Refer to GB / T2406.2-2022 "Determination of Combustion Behavior of Plastics by Oxygen Index Method" to test the minimum oxygen concentration (%) required for the material to maintain combustion in an oxygen-nitrogen mixture; Tensile strength and its retention rate: refer to GB / T2951.21-2008 "General test methods for cable insulation and sheath materials" for testing. After aging the sample in a 250℃ oven for 168 hours, test the tensile strength and calculate the performance retention rate before and after aging. Thermal cycle delamination: the cable sample is kept at -40℃ for 2 hours, then heated to 85℃ and kept for 2 hours, and the cycle is repeated 20 times. The cross section is then observed. The test results are shown in Table 1 below: Table 1

[0039] In combination with the above content, the oxygen index of the unmodified aluminum hydroxide of comparative example 1 decreases by 16%, and the fire-resistant time is shortened by 16%, and the tensile strength retention rate decreases by 17%. The unmodified aluminum hydroxide has poor dispersibility, and the flame retardant efficiency is low and weakens the thermal stability of the material. Comparative example 2 has no modified aluminum hydroxide, and the oxygen index decreases by 20%, and the thermal cycle stratification is serious, and the aluminum hydroxide lacks and causes the flame retardant system to collapse, proving that its endothermic decomposition is crucial to fire resistance. Comparative example 3 has no modified magnesium hydroxide, and the oxygen index decreases by 18%, and stratification is obvious, and the interface bonding of unmodified magnesium hydroxide is weak, which affects the efficiency of flame retardant gas release and the material density. Comparative example 4 has no modified magnesium hydroxide, and the tensile strength retention rate decreases by 24%, and the magnesium hydroxide lack weakens the material anti-aging ability, confirms its smoke suppression and the effect of promoting thermal stability. Comparative example 5 does not add antimony trioxide, and the oxygen index decreases by 12%, and stratification is slight, and the antimony trioxide lack reduces the red phosphorus carbonization efficiency, but the microcapsule structure still provides basic flame retardancy. Comparative Example 6, using unencapsulated red phosphorus, saw a 26% drop in oxygen index and severe delamination. Unencapsulated red phosphorus readily absorbs moisture and hydrolyzes, destroying the polymer structure and losing its vapor-phase flame retardant properties. Comparative Example 7, lacking microencapsulated red phosphorus, saw a 27% decrease in tensile strength retention. The lack of red phosphorus resulted in insufficient char formation, demonstrating that condensed-phase flame retardancy plays a key role in its high-temperature integrity. Therefore, the modified aluminum hydroxide / magnesium hydroxide and microencapsulated red phosphorus / antimony trioxide char formation and smoke suppression successfully constitute a dual flame-retardant system.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high temperature resistant flame retardant cable, characterized in that: The invention comprises a conductor and a flame-retardant outer sheath, wherein the flame-retardant outer sheath is composed of the following raw materials in parts by weight: 40-50 parts of linear low-density polyethylene, 35-45 parts of ethylene-vinyl acetate copolymer, 10-15 parts of EPDM rubber, 15-18 parts of modified aluminum hydroxide, 10-14 parts of modified magnesium hydroxide, 5-8 parts of polyethylene grafted maleic anhydride, 5-8 parts of microencapsulated red phosphorus, 2-3 parts of silane coupling agent, 0.8-1 part of antioxidant, 0.5-1 part of light stabilizer, 0.5-1 part of calcium stearate, 0.8-1 part of polyethylene wax, and 0.5-0.9 part of carbon nanotube.

2. A high temperature resistant flame retardant cable according to claim 1, characterized in that: The preparation method of the modified aluminum hydroxide includes: vacuum drying aluminum hydroxide powder at 100-120°C for 2-4 hours; taking ethanol and water and mixing them evenly, slowly adding silane coupling agent A-151 and stirring at room temperature to obtain a hydrolyzate; dispersing the dried aluminum hydroxide powder in the hydrolyzate; reacting at a temperature of 50-60°C and 200-300rm for 10-12 hours; and centrifugally drying to obtain the modified aluminum hydroxide.

3. A high temperature resistant flame retardant cable according to claim 2, characterized in that: The weight ratio of the dried aluminum hydroxide, ethanol, water and silane coupling agent A-151 is 10g:100-150mL:50-100mL:0.3-0.5g.

4. The high temperature resistant flame retardant cable according to claim 1, characterized in that: The preparation method of the modified magnesium hydroxide comprises: vacuum drying magnesium hydroxide powder at 100-120° C. for 2-4 hours, adding a silane coupling agent Si-69 to anhydrous ethanol, and dropwise adding an acetic acid / water mixture to adjust the pH to 5 to obtain a Si-69 hydrolyzate; dispersing the dried magnesium hydroxide powder in the Si-69 hydrolyzate, reacting at a temperature of 60-70° C. for 8-10 hours, and centrifugally drying to obtain the modified aluminum hydroxide.

5. The high temperature resistant flame retardant cable according to claim 4, characterized in that: The weight ratio of the dried magnesium hydroxide, ethanol and silane coupling agent Si-69 is 10g:180-220mL:0.4-0.6g.

6. The high temperature resistant flame retardant cable according to claim 1, characterized in that: The preparation method of microencapsulated red phosphorus includes: mixing formaldehyde and water, stirring at a rate of 200±20 rpm, heating in a water bath to 50±2°C, adding a NaOH aqueous solution, adjusting the pH to 8.8±0.2, adding melamine, heating at a rate of 2°C / min to 85±2°C, and conducting a constant temperature reaction for 30-50 minutes to prepare a prepolymer; mixing red phosphorus and antimony trioxide, adding water, grinding, and conducting a constant temperature azeotropic reaction at 90-98°C for 1.5-2.5 hours to obtain a mixed system; slowly adding the prepolymer to the mixed system, adding hydrochloric acid to adjust the pH to 3-5, stirring for reaction, centrifuging, washing with water, and drying to obtain the product.

7. The high temperature resistant flame retardant cable according to claim 6, characterized in that: The weight ratio of the formaldehyde, water and melamine is 90-110:300-340:120-130; the weight ratio of the red phosphorus, antimony trioxide and water is 50:20-30:180-220.

8. The high temperature resistant flame retardant cable according to claim 1, characterized in that: The stirring reaction is carried out at 80-90° C. and 300-400 rpm for 50-70 minutes.

9. The high temperature resistant flame retardant cable according to claim 1, characterized in that: The antioxidant includes at least one of antioxidant 1010 , antioxidant 1076 , and antioxidant 168 ; and the light stabilizer includes light stabilizer 770 and / or light stabilizer 944 .

10. A method for preparing a high temperature resistant flame retardant cable according to any one of claims 1 to 9, characterized in that the steps include: The raw materials are weighed according to the formula, stirred and mixed in a high-speed mixer at 40-50° C. and 600-800 rpm for 20-30 minutes; melted through a twin-screw extruder, and extruded at 175-185° C. to form a high-temperature resistant flame-retardant cable.

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