Fireproof flame-retardant 10kV power cable

Abstract

The invention relates to the technical field of cables, and provides a fireproof flame-retardant 10kV power cable and a preparation method thereof. The fire-resistant flame-retardant 10kV power cable comprises a conductor and a fire-resistant flame-retardant layer, the fireproof flame-retardant layer is prepared from the following raw materials in parts by weight: 35 to 45 parts of linear low-density polyethylene, 40 to 50 parts of ethylene-vinyl acetate copolymer, 25 to 30 parts of modified aluminum hydroxide, 5 to 8 parts of polyethylene grafted maleic anhydride, 10 to 12 parts of phosphate modified halloysite nanotube, 5 to 8 parts of ZIF-8 loaded zinc borate core-shell particles, 15 to 20 parts of magnesium hydroxide and 2 to 3 parts of silane coupling agent. 0.5 to 1 part of antioxidant, 0.5 to 1 part of calcium stearate and 1 to 1.5 parts of polyethylene wax. According to the cable prepared in the invention, the situation that a conductor is exposed and the fire resistance is lost due to cracking and falling under long-time high-temperature baking is avoided; the continuous effectiveness of the flame retardant at high temperature is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a fire-resistant and flame-retardant 10kV power cable. Background Art

[0002] With the rapid development of society and the economy, electricity demand is growing. Power cables, as key carriers of power transmission and distribution, have been widely used in various industrial, commercial, and civil fields. As a key component of the medium-voltage distribution system, 10kV power cables are crucial for transmitting electricity from substations to various power terminals. However, in some special scenarios, such as high-rise buildings, underground shopping malls, and industrial plants, where there are dense crowds or high fire risks, more stringent requirements are placed on the fire resistance and flame retardancy of power cables. The emergence of fire-resistant and flame-retardant 10kV power cables provides important support for ensuring the safe and stable operation of power systems in extreme situations such as fires.

[0003] Fire-resistant, flame-retardant 10kV power cables are designed to maintain circuit integrity, continue transmitting power, and effectively prevent the spread of flames in the event of a fire. They typically consist of a conductor, insulation, a fire-resistant and flame-retardant layer, and a sheath. The conductor, serving as the current transmission channel, is typically made of highly conductive copper or aluminum. The insulation isolates the conductor from the external environment, ensuring safe current transmission and is often made of materials such as cross-linked polyethylene. The fire-resistant and flame-retardant layer is a key component of fire-resistant and flame-retardant cables, ensuring mechanical strength and electrical performance under high-temperature flames, ensuring the cable's normal operation during fires.

[0004] The performance of the fire-resistant layer materials of some existing fire-resistant and flame-retardant 10kV power cables decays rapidly under the action of high-temperature flames. For example, some cables that use traditional mica tape as the fire-resistant layer are prone to cracking and falling off after long-term high-temperature baking, resulting in the exposure of the conductor and the loss of fire resistance. Some flame retardants may decompose and become ineffective at high temperatures and cannot continue to exert their flame retardant effect. Moreover, the formula and structural design of the flame retardant layer are not optimized enough, resulting in the flame not being quickly contained when spreading on the cable surface, which easily causes the fire to expand. In order to solve the above technical problems, the present invention proposes a new fire-resistant and flame-retardant 10kV power cable. Summary of the Invention

[0005] The present invention proposes a fire-resistant and flame-retardant 10kV power cable and a preparation method thereof, which improves the problem of rapid performance degradation of the fire-resistant layer material of the existing fire-resistant and flame-retardant 10kV power cable under the action of high-temperature flames, avoids the situation where cracking and falling off caused by long-term high-temperature baking lead to the exposure of the conductor and loss of fire resistance; and improves the sustained effectiveness of the flame retardant at high temperature to prevent its decomposition and failure.

[0006] The technical solutions of the present invention are as follows: In the first aspect, the present invention proposes a fire-resistant and flame-retardant 10kV power cable, comprising a conductor and a fire-resistant and flame-retardant layer, wherein the fire-resistant and flame-retardant layer is composed of the following raw materials in parts by weight: 35-45 parts of linear low-density polyethylene, 40-50 parts of ethylene-vinyl acetate copolymer, 25-30 parts of modified aluminum hydroxide, 5-8 parts of polyethylene grafted maleic anhydride, 10-12 parts of phosphate-modified halloysite nanotubes, 5-8 parts of ZIF-8 loaded zinc borate core-shell particles, 15-20 parts of magnesium hydroxide, 2-3 parts of silane coupling agent, 0.5-1 part of antioxidant, 0.5-1 part of calcium stearate, and 1-1.5 parts of polyethylene wax.

[0007] As a further technical solution, the preparation method of the modified aluminum hydroxide includes: dispersing aluminum hydroxide powder in water, adding dopamine hydrochloride and reacting at pH 8.5-9.0 for 6-8 hours, adding silane coupling agent KH550, continuing the reaction at a temperature of 50-60°C for 10-12 hours, and obtaining modified aluminum hydroxide after centrifugal drying.

[0008] As a further technical solution, the weight ratio of the aluminum hydroxide, water, dopamine hydrochloride and KH550 is 10g:150-200mL:0.2-0.4g:0.3-0.5g.

[0009] As a further technical solution, the preparation method of the phosphate-modified halloysite nanotubes includes: dispersing the halloysite nanotubes in water at 60-70°C, adding a phosphoric acid solution with a mass concentration of 10%-15% and a silane coupling agent KH570, reacting for 3-4 hours under ultrasonic assistance at a power of 150-250W, and centrifuging, washing, and drying to obtain the obtained product.

[0010] As a further technical solution, the weight ratio of the halloysite, phosphoric acid solution and KH570 is 1g:50-100mL:10-15mL:0.05-0.15g.

[0011] As a further technical solution, the preparation method of the ZIF-8 loaded zinc borate core-shell particles comprises: dispersing zinc borate in methanol, adding zinc nitrate and 2-methylimidazole, and reacting at 25-35° C. for 6-8 hours to obtain the particles.

[0012] As a further technical solution, the molar ratio of the zinc borate, ethanol, zinc nitrate and 2-methylimidazole is 1g:50-100mL:0.5-1g:1.5-3g.

[0013] As a further technical solution, the antioxidant includes antioxidant 1010 and / or antioxidant 168.

[0014] In a second aspect, the present invention proposes a method for preparing a fire-resistant and flame-retardant 10kV power cable, the steps comprising: weighing raw materials according to a formula, mixing them in a high-speed mixer at 1000-1200rpm for 15-20min; and melt-extruding a coated conductor through a twin-screw extruder to form a fire-resistant and flame-retardant 10kV power cable.

[0015] As a further technical solution, the temperature of the twin-screw extruder is 160-180°C.

[0016] The working principle and beneficial effects of the present invention are: The present invention constructs a triple flame retardant mechanism of "gas phase flame retardancy - condensed phase catalytic carbonization - carbon layer reinforcement" through the synergistic effect of multiple components. Among them, modified aluminum hydroxide enhances interfacial bonding, phosphoric acid-modified halloysite nanotubes promote the formation of a dense carbon layer, and ZIF-8-loaded zinc borate core-shell particles control the slow release of the flame retardant to form a complementary effect, achieving excellent performance of fire resistance time ≥89 minutes, LOI ≥35%, and residual carbon rate ≥52%.

[0017] When aluminum hydroxide decomposes under heat, it absorbs a large amount of heat, which has a cooling effect, while also releasing water vapor, which dilutes combustible gases. In the present invention, the modified aluminum hydroxide is more evenly dispersed in the polymer matrix, effectively reducing particle agglomeration and improving compatibility with the matrix, thereby better exerting its flame retardant and fire-resistant properties.

[0018] In addition, the components such as the phosphate-modified halloysite nanotubes in the present invention can catalyze the polymer matrix to form a dense carbon layer during the combustion process. The presence of phosphate groups promotes the dehydration, cross-linking and other reactions of the polymer at high temperature, accelerating the formation of the carbon layer. The dense carbon layer effectively isolates the transfer of heat and oxygen, preventing the further spread of combustion. The halloysite nanotubes themselves have a nanoscale tubular structure and a large specific surface area. After being modified with phosphate groups, not only the acid sites on the surface are increased, the catalytic carbonization ability is improved, but also the compatibility with the polymer matrix is improved by grafting the silane coupling agent KH570. During combustion, the phosphate-modified halloysite nanotubes can more efficiently promote the polymer to form a dense carbon layer and enhance the barrier properties of the carbon layer.

[0019] The ZIF-8 loaded zinc borate core-shell particles and other components in the present invention have a strengthening effect on the carbon layer. ZIF-8 loaded with zinc borate forms a core-shell structure, which has unique advantages. The ZIF-8 shell can control the release rate of zinc borate to prevent it from decomposing prematurely. During the combustion process, zinc borate is slowly released and synergistically acts with the carbon layer to enhance the thermal stability and mechanical strength of the carbon layer. At the same time, ZIF-8 itself also has certain flame retardant properties, further enhancing the flame retardant effect of the entire fire-resistant flame retardant layer. In addition, ZIF-8, as a metal-organic framework material, has a unique pore structure and a high specific surface area, which can effectively load zinc borate and control its release rate. During the combustion process, zinc borate is slowly released and interacts with the carbon layer, enhancing the thermal stability and mechanical strength of the carbon layer, and further enhancing the barrier properties of the carbon layer. DETAILED DESCRIPTION

[0020] 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.

[0021] 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's reagent; ethylene-vinyl acetate copolymer, CAS No.: 24937-78-8, MDL No.: MFCD00133996, Article No.: P815474, was purchased from MacLean's reagent.

[0022] Example 1 This embodiment provides a fire-resistant and flame-retardant 10kV power cable, including a conductor and a fire-resistant and flame-retardant layer, wherein the fire-resistant and flame-retardant layer 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, 28 parts of modified aluminum hydroxide, 7 parts of polyethylene grafted maleic anhydride, 11 parts of phosphate-modified halloysite nanotubes, 6 parts of ZIF-8 loaded zinc borate core-shell particles, 18 parts of magnesium hydroxide, 2.5 parts of silane coupling agent KH550, 0.8 parts of antioxidant, 0.8 parts of calcium stearate, and 1.2 parts of polyethylene wax.

[0023] The preparation method of modified aluminum hydroxide includes: dispersing 10g of aluminum hydroxide powder in 180mL of water, adding 0.3g of dopamine hydrochloride and reacting at pH 8.8 for 7h, adding 0.4g of silane coupling agent KH550, continuing to react at a temperature of 55°C for 11h, centrifuging at 9000 rpm for 18 minutes, collecting the precipitate, washing the precipitate with deionized water three times until neutral, drying in a vacuum drying oven at 60°C for 13 hours, and crushing through a 200-mesh sieve to obtain modified aluminum hydroxide; The preparation method of phosphate-modified halloysite nanotubes includes: dispersing 1 g of halloysite nanotubes in 80 mL of 65°C water, adding 12 mL of a 12% mass concentration phosphoric acid solution and 0.1 g of a silane coupling agent KH570, reacting under 200 W ultrasonic assistance for 3.5 hours, centrifuging at 6000 rpm for 10 minutes, washing three times alternately with ethanol and deionized water, and drying under vacuum at 60°C for 8 hours to obtain the obtained nanotubes. The preparation method of ZIF-8 loaded zinc borate core-shell particles includes: dispersing 1g of zinc borate in 80mL of methanol, adding 0.8g of zinc nitrate and 2.2g of 2-methylimidazole at 500rpm under nitrogen protection, reacting at 30°C for 7h, centrifuging at 10000rpm for 5min, washing with methanol three times, and then vacuum drying at 50°C for 6h and passing through a 400-mesh sieve to obtain the obtained particles; The antioxidants are antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; The preparation method of this fire-resistant and flame-retardant 10kV power cable includes the following steps: weighing raw materials according to a formula, drying them in an 80°C oven for 4 hours, and then mixing them in a 1100rpm high-speed mixer for 18 minutes; using a twin-screw extruder to control the first zone: 160°C, the second zone: 170°C, the third zone: 175°C, and the fourth zone: 180°C for melt extrusion of the coated conductor, with a screw length-to-diameter ratio of 32:1, a rotation speed of 300 rpm, a die head pressure maintained at 9MPa, and a coating thickness controlled to 2mm to form a fire-resistant and flame-retardant 10kV power cable.

[0024] Example 2 This embodiment provides a fire-resistant and flame-retardant 10kV power cable, including a conductor and a fire-resistant and flame-retardant layer, wherein the fire-resistant and flame-retardant layer is composed of the following raw materials in parts by weight: 35 parts of linear low-density polyethylene, 40 parts of ethylene-vinyl acetate copolymer, 25 parts of modified aluminum hydroxide, 5 parts of polyethylene grafted maleic anhydride, 10 parts of phosphate-modified halloysite nanotubes, 5 parts of ZIF-8 loaded zinc borate core-shell particles, 15 parts of magnesium hydroxide, 2 parts of silane coupling agent KH550, 0.5 parts of antioxidant, 0.5 parts of calcium stearate, and 1 part of polyethylene wax.

[0025] The preparation method of modified aluminum hydroxide includes: dispersing 10g of aluminum hydroxide powder in 150mL of water, adding 0.2g of dopamine hydrochloride and reacting at pH 8.5 for 6h, adding 0.3g of silane coupling agent KH550, continuing to react at a temperature of 50°C for 10h, centrifuging at 8000 rpm for 15 minutes, collecting the precipitate, washing the precipitate with deionized water three times until neutral, drying in a vacuum drying oven at 60°C for 12 hours, and crushing through a 200-mesh sieve to obtain modified aluminum hydroxide; The preparation method of phosphate-modified halloysite nanotubes includes: dispersing 1 g of halloysite nanotubes in 50 mL of 60°C water, adding 10 mL of a 10% mass concentration phosphoric acid solution and 0.05 g of a silane coupling agent KH570, reacting under 150 W ultrasonic assistance for 3 hours, centrifuging at 6000 rpm for 10 minutes, washing alternately with ethanol and deionized water three times, and drying under vacuum at 60°C for 8 hours to obtain the obtained product. The preparation method of ZIF-8 loaded zinc borate core-shell particles includes: dispersing 1g of zinc borate in 50mL of methanol, adding 0.5g of zinc nitrate and 1.5g of 2-methylimidazole under nitrogen protection at 500rpm, reacting at 25°C for 6h, centrifuging at 10000rpm for 5min, washing with methanol three times, and then vacuum drying at 50°C for 6h and passing through a 400-mesh sieve to obtain the obtained particles; The antioxidants are antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; The preparation method of this fire-resistant and flame-retardant 10kV power cable includes the following steps: weighing raw materials according to a formula, drying them in an 80°C oven for 4 hours, and then mixing them in a 10,000 rpm high-speed mixer for 15 minutes; and melt-extruding a coated conductor through a twin-screw extruder at 160°C in zone one, 170°C in zone two, 175°C in zone three, and 180°C in zone four, with a screw length-to-diameter ratio of 32:1, a rotation speed of 300 rpm, a die head pressure maintained at 8 MPa, and a coating thickness controlled to 2 mm to form a fire-resistant and flame-retardant 10kV power cable.

[0026] Example 3 This embodiment provides a fire-resistant and flame-retardant 10kV power cable, including a conductor and a fire-resistant and flame-retardant layer, wherein the fire-resistant and flame-retardant layer is composed of the following raw materials in parts by weight: 45 parts of linear low-density polyethylene, 50 parts of ethylene-vinyl acetate copolymer, 30 parts of modified aluminum hydroxide, 8 parts of polyethylene grafted maleic anhydride, 12 parts of phosphate-modified halloysite nanotubes, 8 parts of ZIF-8 loaded zinc borate core-shell particles, 20 parts of magnesium hydroxide, 3 parts of silane coupling agent KH550, 1 part of antioxidant, 1 part of calcium stearate, and 1.5 parts of polyethylene wax.

[0027] The preparation method of modified aluminum hydroxide includes: dispersing 10g of aluminum hydroxide powder in 200mL of water, adding 0.4g of dopamine hydrochloride and reacting at pH 9.0 for 8h, adding 0.5g of silane coupling agent KH550, continuing to react at a temperature of 60°C for 12h, centrifuging at 10000 rpm for 20 minutes, collecting the precipitate, washing the precipitate with deionized water three times until neutral, drying in a vacuum drying oven at 60°C for 14 hours, and crushing through a 200-mesh sieve to obtain modified aluminum hydroxide; The preparation method of phosphate-modified halloysite nanotubes includes: dispersing 1 g of halloysite nanotubes in 100 mL of 70°C water, adding 15 mL of a 15% mass concentration phosphoric acid solution and 0.15 g of a silane coupling agent KH570, reacting under ultrasonic assistance at a power of 250 W for 4 hours, centrifuging at 6000 rpm for 10 minutes, washing alternately with ethanol and deionized water three times, and drying under vacuum at 60°C for 8 hours to obtain the obtained product. The preparation method of ZIF-8 loaded zinc borate core-shell particles includes: dispersing 1g of zinc borate in 100mL of methanol, adding 1g of zinc nitrate and 3g of 2-methylimidazole under nitrogen protection at 500rpm, reacting at 35°C for 8h, centrifuging at 10000rpm for 5min, washing with methanol three times, and then vacuum drying at 50°C for 6h and passing through a 400-mesh sieve to obtain the obtained particles; The antioxidants are antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; The preparation method of this fire-resistant and flame-retardant 10kV power cable includes the following steps: weighing raw materials according to a formula, drying them in an 80°C oven for 4 hours, and then mixing them in a 1200rpm high-speed mixer for 20 minutes; using a twin-screw extruder to control the first zone: 160°C, the second zone: 170°C, the third zone: 175°C, and the fourth zone: 180°C for melt extrusion of the coated conductor, with a screw length-to-diameter ratio of 32:1, a rotation speed of 300 rpm, a die head pressure maintained at 10 MPa, and a coating thickness controlled to 2 mm to form a fire-resistant and flame-retardant 10kV power cable.

[0028] Example 4 This embodiment provides a fire-resistant and flame-retardant 10kV power cable, including a conductor and a fire-resistant and flame-retardant layer, wherein the fire-resistant and flame-retardant layer is composed of the following raw materials in parts by weight: 35 parts of linear low-density polyethylene, 50 parts of ethylene-vinyl acetate copolymer, 25 parts of modified aluminum hydroxide, 8 parts of polyethylene grafted maleic anhydride, 10 parts of phosphate-modified halloysite nanotubes, 8 parts of ZIF-8 loaded zinc borate core-shell particles, 15 parts of magnesium hydroxide, 3 parts of silane coupling agent KH550, 0.5 parts of antioxidant, 1 part of calcium stearate, and 1 part of polyethylene wax.

[0029] The preparation method of modified aluminum hydroxide includes: dispersing 10g of aluminum hydroxide powder in 200mL of water, adding 0.2g of dopamine hydrochloride and reacting at pH 9.0 for 6h, adding 0.5g of silane coupling agent KH550, continuing to react at a temperature of 50°C for 12h, centrifuging at 8000rpm for 20 minutes, collecting the precipitate, washing the precipitate with deionized water three times until neutral, drying in a vacuum drying oven at 60°C for 12 hours, and crushing through a 200-mesh sieve to obtain modified aluminum hydroxide; The preparation method of phosphate-modified halloysite nanotubes includes: dispersing 1 g of halloysite nanotubes in 100 mL of 60°C water, adding 15 mL of a 10% mass concentration phosphoric acid solution and 0.15 g of a silane coupling agent KH570, reacting under 150 W ultrasonic assistance for 4 hours, centrifuging at 6000 rpm for 10 minutes, washing alternately with ethanol and deionized water three times, and drying under vacuum at 60°C for 8 hours to obtain the obtained product. The preparation method of ZIF-8-loaded zinc borate core-shell particles includes: dispersing 1g of zinc borate in 50mL of methanol, adding 1g of zinc nitrate and 1.5g of 2-methylimidazole under nitrogen protection at 500rpm, reacting at 35°C for 6h, centrifuging at 10000rpm for 5min, washing with methanol three times, and then vacuum drying at 50°C for 6h and passing through a 400-mesh sieve to obtain the obtained particles; The antioxidants are antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; The preparation method of this fire-resistant and flame-retardant 10kV power cable includes the following steps: weighing raw materials according to a formula, drying them in an 80°C oven for 4 hours, and then mixing them in a 1200rpm high-speed mixer for 15 minutes; and melt-extruding a coated conductor through a twin-screw extruder at 160°C in zone one, 170°C in zone two, 175°C in zone three, and 180°C in zone four, with a screw length-to-diameter ratio of 32:1, a rotation speed of 300 rpm, a die head pressure maintained at 10 MPa, and a coating thickness controlled to 2 mm to form a fire-resistant and flame-retardant 10kV power cable.

[0030] 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 Example 1, and the preparation steps were the same as in Example 1.

[0031] Comparative Example 2 In this comparative example, the phosphate-modified halloysite nanotubes were replaced by unmodified halloysite nanotubes, and no phosphoric acid treatment was performed. The rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0032] Comparative Example 3 In this comparative example, the ZIF-8 loaded zinc borate core-shell particles were replaced by ordinary zinc borate powder without loading ZIF-8, and the rest were the same as in Example 1, and the preparation steps were the same as in Example 1.

[0033] Comparative Example 4 This comparative example does not include modified aluminum hydroxide, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0034] Comparative Example 5 This comparative example does not include phosphate-modified halloysite nanotubes, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0035] Comparative Example 6 This comparative example does not include ZIF-8 loaded zinc borate core-shell particles, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0036] Test Example 1: The fire-resistant and flame-retardant 10kV power cables prepared in the above Examples 1-4 and Comparative Examples 1-6 were subjected to the following tests: Fire resistance test: Refer to GB / T19216.21-2003 "Line integrity test for electric or optical cables under fire conditions" for the test. The cable sample is placed in a 950°C flame for 90 minutes while applying a rated voltage of 10kV. The presence of cracks or shedding of the insulation layer and the exposure time of the conductor are recorded. Flame retardant performance test: Refer to GB / T18380.12-2022 "Combustion test of electric and optical cables under flame conditions" for testing. Use a vertical combustion test to record the carbonization height, self-extinguishing time, and whether the dripping material ignites the cotton layer below. Thermal stability analysis: Tested in accordance with ISO11358-1-2014 "Thermogravimetric Analysis (TGA) of Plastics" using a thermogravimetric analyzer (TGA) in a nitrogen atmosphere at a heating rate of 10°C / min to 800°C, recording the carbon residue rate and maximum decomposition temperature of the material. 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. The test results are shown in Table 1 below: Table 1

[0037] In combination with the above content, the hydroxyl groups on the surface of unmodified aluminum hydroxide in Comparative Example 1 caused particle agglomeration, weak interface bonding caused stress concentration, and reduced tensile strength retention; the carbonization height of Comparative Example 2 increased by 76.7%, and the self-extinguishing time was extended by 433%. The acidic sites of the unphosphoric acid-treated halloysite nanotubes were insufficient, the catalytic carbonization ability was reduced, and the surface was not grafted with KH570, resulting in poor compatibility with the polymer and more cracks during combustion; the oxygen index of Comparative Example 3 was reduced by 29.8%, and the self-extinguishing time was extended by 533%; the loss of the ZIF-8 shell caused the premature decomposition of zinc borate, and the failure to form a core-shell structure caused the flame retardant release rate to be out of control; Comparative Example 4 had the worst comprehensive performance, with a fire resistance time of only 61 minutes; the complete lack of aluminum hydroxide caused the endothermic dehydration reaction to disappear; the residual carbon rate of Comparative Example 5 plummeted by 43.5%, and the oxygen index of Comparative Example 6 dropped drastically by 42.2%, and the tensile strength retention rate was the lowest, indicating that ZIF-8 loaded zinc borate core-shell particles are indispensable for synergistic flame retardancy and thermal stability.

[0038] 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 fire-resistant and flame-retardant 10kV power cable, characterized in that: The invention comprises a conductor and a fire-resistant and flame-retardant layer, wherein the fire-resistant and flame-retardant layer is composed of the following raw materials in parts by weight: 35-45 parts of linear low-density polyethylene, 40-50 parts of ethylene-vinyl acetate copolymer, 25-30 parts of modified aluminum hydroxide, 5-8 parts of polyethylene grafted maleic anhydride, 10-12 parts of phosphate-modified halloysite nanotubes, 5-8 parts of ZIF-8 loaded zinc borate core-shell particles, 15-20 parts of magnesium hydroxide, 2-3 parts of silane coupling agent, 0.5-1 part of antioxidant, 0.5-1 part of calcium stearate, and 1-1.5 parts of polyethylene wax.

2. A fire-resistant and flame-retardant 10kV power cable according to claim 1, characterized in that: The preparation method of the modified aluminum hydroxide comprises: dispersing aluminum hydroxide powder in water, adding dopamine hydrochloride and reacting at a pH of 8.5-9.0 for 6-8 hours, adding a silane coupling agent KH550, continuing the reaction at a temperature of 50-60° C. for 10-12 hours, and obtaining the modified aluminum hydroxide after centrifugal drying.

3. A fire-resistant and flame-retardant 10kV power cable according to claim 2, characterized in that: The weight ratio of the aluminum hydroxide, water, dopamine hydrochloride and KH550 is 10g:150-200mL:0.2-0.4g:0.3-0.5g.

4. The fire-resistant and flame-retardant 10kV power cable according to claim 1, characterized in that: The preparation method of the phosphate-modified halloysite nanotubes comprises: dispersing the halloysite nanotubes in 60-70° C. water, adding a 10%-15% mass concentration of phosphoric acid solution and a silane coupling agent KH570, reacting for 3-4 hours under the assistance of ultrasound at a power of 150-250W, and centrifugally washing and drying to obtain the obtained product.

5. The fire-resistant and flame-retardant 10kV power cable according to claim 4, characterized in that: The weight ratio of the halloysite, phosphoric acid solution and KH570 is 1g:50-100mL:10-15mL:0.05-0.15g.

6. The fire-resistant and flame-retardant 10kV power cable according to claim 1, characterized in that: The preparation method of the ZIF-8 loaded zinc borate core-shell particles comprises: dispersing zinc borate in methanol, adding zinc nitrate and 2-methylimidazole, and reacting at 25-35° C. for 6-8 hours to obtain the particles.

7. The fire-resistant and flame-retardant 10kV power cable according to claim 6, characterized in that: The molar ratio of the zinc borate methanol, zinc nitrate and 2-methylimidazole is 1g:50-100mL:0.5-1g:1.5-3g.

8. The fire-resistant and flame-retardant 10kV power cable according to claim 1, characterized in that: The antioxidant includes antioxidant 1010 and / or antioxidant 168.

9. A method for preparing a fire-resistant and flame-retardant 10kV power cable according to any one of claims 1 to 8, characterized in that the steps include: The raw materials are weighed according to the formula and mixed in a high-speed mixer at 1000-1200 rpm for 15-20 minutes; and the conductor is melt-extruded and coated through a twin-screw extruder to form a fire-resistant and flame-retardant 10kV power cable.

10. The method for preparing a fire-resistant and flame-retardant 10kV power cable according to claim 9, characterized in that: The temperature of the twin-screw extruder is 160-180°C.

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