Fire resistant low voltage power cable

Abstract

This invention discloses a fire-resistant and flame-retardant low-voltage power cable, comprising, from the inside out, a conductor, a fire-resistant insulation layer, a flame-retardant isolation layer, an armor layer, and a low-smoke halogen-free flame-retardant outer sheath. The fire-resistant insulation layer tightly covers the conductor and is a ceramicized silicone rubber composite material. This ceramicized silicone rubber composite material can form a dense ceramic layer at high temperatures of 600–1000℃. Multiple conductors covered with fire-resistant insulation layers are stranded to form a cable core. The flame-retardant isolation layer tightly wraps around the cable core and is an intumescent flame-retardant tape. The armor layer is fitted over the flame-retardant isolation layer and has a stainless steel wire braided structure. The low-smoke halogen-free flame-retardant outer sheath covers the armor layer. This invention utilizes an intumescent flame-retardant tape, combined with nano-montmorillonite synergistic flame retardant, to enhance the fire-induced expansion effect, enabling the rapid formation of a continuous, dense, and high-strength carbon foam barrier layer.

Description

Technical Field

[0001] This invention relates to the field of power cable technology, and in particular to a fire-resistant and flame-retardant low-voltage power cable. Background Technology

[0002] Low-voltage power cables are the core carriers for building power distribution, industrial equipment power supply, and infrastructure wiring. Their fire resistance and flame retardant properties are directly related to personnel evacuation, equipment safety, and continuous power supply in fire scenarios.

[0003] Traditional cables often use intumescent flame-retardant insulation layers, which consist mainly of a single intumescent flame-retardant component and a binder. The interfacial adhesion between the substrate and the coating is weak, resulting in poor and uneven expansion upon exposure to fire, making it difficult to form a continuous and dense barrier layer. This allows flames to easily penetrate the insulation layer and spread to the cable core. Furthermore, combustion produces large amounts of smoke and toxic gases, hindering rescue operations at fire scenes and posing serious health risks. Therefore, this application proposes a fire-resistant and flame-retardant low-voltage power cable. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a fire-resistant and flame-retardant low-voltage power cable.

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

[0006] A fire-resistant and flame-retardant low-voltage power cable includes, from the inside out, a conductor, a fire-resistant insulation layer, a flame-retardant isolation layer, an armor layer, and a low-smoke halogen-free flame-retardant outer sheath.

[0007] The fire-resistant insulating layer tightly covers the outside of the conductor. The fire-resistant insulating layer is a ceramicized silicone rubber composite material. The ceramicized silicone rubber composite material can form a dense ceramic layer at a high temperature of 600-1000℃.

[0008] Multiple conductors covered with fire-resistant insulation layers are twisted together to form a cable core, and the flame-retardant isolation layer is tightly wrapped around the outside of the cable core. The flame-retardant isolation layer is an intumescent flame-retardant tape.

[0009] The armor layer is fitted over the flame-retardant isolation layer, and the armor layer is a stainless steel wire braided structure;

[0010] The low-smoke halogen-free flame-retardant outer sheath covers the outside of the armor layer, and the low-smoke halogen-free flame-retardant outer sheath is a low-smoke halogen-free polyolefin composite material.

[0011] Preferably, the ceramicized silicone rubber composite material is composed of the following raw materials in the indicated weight ratios:

[0012] 60-80 parts of silicone rubber matrix, 25-32 parts of ceramic powder, 12-18 parts of flame retardant, 3-6 parts of coupling agent, 1-3 parts of antioxidant, and 2-4 parts of synergistic ceramic agent;

[0013] The ceramic powder is a mixture of kaolin and silicon dioxide, with a weight ratio of 1.2:1 to 2.2:1.

[0014] The flame retardant is a compound of magnesium hydroxide and aluminum hydroxide in a weight ratio of 1.5:1 to 3.5:2, and both have undergone surface modification treatment.

[0015] The coupling agent is a compound of silane coupling agents KH550 and KH560 in a weight ratio of 1:1;

[0016] The antioxidant is a compound of antioxidant 1010 and auxiliary antioxidant DLTP in a weight ratio of 2:1.

[0017] The synergistic ceramic-forming agent is a compound of talc powder and mica powder in a weight ratio of 1:1, with a particle size of 5-10 μm.

[0018] Preferably, the preparation process of the ceramicized silicone rubber composite material includes the following steps:

[0019] Raw material pretreatment: Place ceramic powder and synergistic ceramicizing agent in an oven at 110-120℃ and dry for 2-3 hours to remove moisture; preheat silicone rubber matrix at 60-80℃ for 30 minutes to soften the matrix; after surface modification treatment, flame retardant is dried at 90℃ for 1 hour; coupling agent and antioxidant are stored in a sealed container at room temperature and stirred evenly before use.

[0020] Premixing: Place the pretreated silicone rubber matrix into a mixer and stir for 5 to 8 minutes at a temperature of 90 to 100°C and a speed of 50 to 80 r / min. Then add the complex coupling agent and continue stirring for 3 to 5 minutes to ensure that the coupling agent is evenly dispersed in the silicone rubber matrix.

[0021] Filler mixing: Pretreated ceramic powder, synergistic ceramicizing agent, modified flame retardant and compound antioxidant are added to the internal mixer in sequence. During this process, the top plug of the internal mixer is opened once every 3 minutes to exhaust the air, so that the filler and silicone rubber matrix are fully integrated to form a uniform mixed rubber compound.

[0022] Mixing and homogenization: Transfer the mixed rubber compound to a two-roll mill and pass it through a thin mill 4 to 6 times at a temperature of 75 to 85°C. The thickness of each pass should be controlled at 0.5 to 1 mm. Then adjust the roller gap to 2 to 3 mm and run the mill for 6 to 10 minutes. During this period, the mill is turned over multiple times to further improve the uniformity of the rubber compound.

[0023] Cooling and granulation: The homogenized rubber compound is placed in a cooler and cooled to room temperature. Then, it is cut into granules with a particle size of 3-5 mm by a pelletizer, sealed and stored for later use, thus obtaining ceramicized silicone rubber composite material.

[0024] Preferably, the intumescent flame-retardant tape is composed of the following raw materials in the indicated weight ratio:

[0025] 40-60 parts of base material, 35-50 parts of intumescent flame retardant, 6-12 parts of binder, 4-9 parts of smoke suppressant, 2-5 parts of synergistic flame retardant, and 1-3 parts of toughening agent;

[0026] The substrate is made of glass fiber cloth with a basis weight of 90-130 g / m², and the surface is treated with plasma.

[0027] The intumescent flame retardant is a compound of ammonium polyphosphate, pentaerythritol and melamine, with a weight ratio of 3.5:1.2:1 to 5.5:2.2:1.

[0028] The adhesive is a blend of waterborne polyurethane resin and waterborne epoxy resin in a weight ratio of 2:1, with a solid content of 35% to 55%.

[0029] The smoke suppressant is a compound of ammonium molybdate and nano-magnesium hydroxide in a weight ratio of 1:1.5, and the nano-magnesium hydroxide has a particle size of 50-100 nm.

[0030] The synergistic flame retardant is nano-montmorillonite with a particle size of 20–50 nm; the toughening agent is a water-based acrylic emulsion with a solid content of 40%–50%.

[0031] The flame retardant and smoke suppressant composite is a mixture of nano zinc oxide and carbon black in a weight ratio of 2:1. The nano zinc oxide has a particle size of 30-80 nm, and the carbon black has a particle size of 10-30 nm.

[0032] Preferably, the preparation process of the intumescent flame-retardant tape includes the following steps:

[0033] Raw material pretreatment: The intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are sieved separately and then dried in a vacuum drying oven; the substrate is treated with plasma after surface impurities are removed by dust removal equipment; the binder and toughening agent are mixed evenly in proportion and ultrasonically dispersed for 15 minutes before use.

[0034] Mixing and pulping: The pretreated intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are put into a high-speed mixer to obtain a mixed powder; the mixture of compound binder and toughening agent is slowly added to the mixed powder, and mixing continues. Deionized water is added according to the viscosity of the slurry to adjust the solid content of the system to 45% to 65% to form a paste slurry. Let it stand for 8 minutes to eliminate air bubbles.

[0035] Double-sided coating: The pretreated substrate is laid flat on the unwinding device of the coating machine. The unwinding tension is adjusted to 3-5N. A combined coating method of doctor blade and roller coating is adopted. First, the first side is coated by doctor blade. After preliminary drying in the pre-drying tunnel, the second side is coated by roller coating to ensure uniform coating.

[0036] Segmented drying: The coated substrate is sent into a continuous drying chamber and a three-stage drying process is adopted: the first stage temperature is 85-95℃ and the time is 18-25 minutes; the second stage temperature is 105-115℃ and the time is 22-28 minutes; the third stage temperature is 125-135℃ and the time is 12-18 minutes. The air velocity in the drying chamber is controlled at 1.2-1.8m / s to maintain good ventilation.

[0037] Cooling and cutting: The dried flame-retardant tape is cooled to room temperature by cooling rollers at a temperature of 25-30℃, and then cut into strip structures with a width of 20-50mm by a slitting machine at a cutting speed of 35-55r / min. The cutting is assisted by ultrasonic cutting to prevent the substrate fibers from fuzzing.

[0038] Inspection and storage: Sampling inspection ensures that the product thickness is 0.35-0.55mm, the tensile strength is not less than 60N / cm, the expansion ratio when exposed to fire is 18-30 times, and the smoke density level during combustion is ≤65. After passing the inspection, the product is sealed and stored in a dry and ventilated warehouse with a humidity of 50%-60%.

[0039] Preferably, the preparation process of the flame retardant and smoke suppressant composite agent includes the following steps:

[0040] Raw material pretreatment: Select zinc oxide powder and carbon black powder. Put the zinc oxide powder into a ball mill and coarsely grind for 30 minutes to obtain fine powder; dry the carbon black powder in a 100℃ oven for 1 hour to remove surface adsorbed water.

[0041] Solution preparation: Weigh the pretreated zinc oxide and carbon black at a weight ratio of 2:1, add them to deionized water, and add polyethylene glycol 400 dispersant accounting for 0.5% of the total mass of the mixed powder. Stir to form a suspension.

[0042] Ultrasonic dispersion: The suspension is placed in an ultrasonic dispersion device to disperse the powder agglomerates;

[0043] Coprecipitation reaction: The uniformly dispersed suspension is heated to 70-80℃, and a 1mol / L ammonium bicarbonate solution is slowly added dropwise to adjust the pH of the system to 8.0-8.5. The mixture is stirred at a constant temperature for 2 hours to form a zinc salt-carbon black composite precipitate.

[0044] Solid-liquid separation: The mixture after the reaction is placed in a centrifuge to separate the precipitate. The precipitate is washed repeatedly with deionized water 3 to 4 times until the pH of the washing solution is neutral.

[0045] Calcination activation: After the washed precipitate is dried in an oven for 4 hours, it is transferred to a muffle furnace and heated to 450-500℃ at a heating rate of 5℃ / min under a nitrogen protective atmosphere, and then calcined at a constant temperature for 2 hours.

[0046] Crushing and sieving: After the calcined composite solid is crushed by a high-speed crusher, it is passed through a standard sieve and the powder under the sieve is collected;

[0047] Finished product storage: Pack the sieved composite powder into a sealed, moisture-proof container and store it in a dry, ventilated place for later use.

[0048] Preferably, the thickness of the fire-resistant insulation layer is 0.8 to 1.2 mm, the wrapping overlap rate of the flame-retardant isolation layer is 25% to 35%, and the thickness of the formed flame-retardant isolation layer is 0.5 to 0.8 mm.

[0049] Preferably, the outer surface of the flame-retardant isolation layer is provided with an anti-slip texture, which is used to enhance the friction between the flame-retardant isolation layer and the armor layer.

[0050] The present invention has the following beneficial effects:

[0051] 1. The intumescent flame retardant tape of this application adopts an intumescent flame retardant system composed of ammonium polyphosphate, pentaerythritol and melamine, combined with nano-montmorillonite synergistic flame retardant, which improves the expansion effect when exposed to fire, and can quickly form a continuous, dense and high-strength carbon foam barrier layer, effectively blocking the conduction path of flame and heat to the cable core.

[0052] 2. This application uses ammonium molybdate and nano-magnesium hydroxide compound smoke suppressant, combined with a special flame retardant and smoke suppressant composite agent. Through the synergistic effect of multiple components, it significantly inhibits the amount of smoke generated during combustion and reduces smoke density. In addition, the cable adopts a fully halogen-free design, which can effectively avoid the release of toxic halogen acid gases commonly seen when traditional flame-retardant cables burn. Only a small amount of non-toxic thermal decomposition gases may be produced, which greatly improves the visibility at the fire scene, reduces the harm to rescue personnel and the surrounding environment, and meets the environmental safety requirements of critical locations.

[0053] 3. The intumescent flame-retardant tape of this application uses a plasma-treated substrate, combined with a binder of water-based polyurethane resin and water-based epoxy resin, and a toughening agent is added to significantly improve the interfacial bonding force between the substrate and the coating, solve the problem of easy peeling off of the flame-retardant tape coating, and ensure that the flame-retardant isolation layer structure is intact under the conditions of cable laying, bending and other working conditions, and will not lose its protective function due to interlayer peeling. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the overall structure of a fire-resistant and flame-retardant low-voltage power cable proposed in this invention.

[0055] In the diagram: 1. Conductor; 2. Fire-resistant insulation layer; 3. Flame-retardant isolation layer; 4. Armor layer; 5. Low-smoke halogen-free flame-retardant outer sheath. Detailed Implementation

[0056] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0057] Example 1: Power distribution cable suitable for vertical shafts and evacuation passages in high-rise buildings. Raw material preparation: The conductor is oxygen-free copper wire, 0.2mm in diameter, stranded to form a conductor with a cross-sectional area of ​​2.5mm². Ceramicized silicone rubber composite material raw materials: 70 parts silicone rubber matrix, 28 parts ceramic powder (kaolin:silica = 1.8:1), 15 parts flame retardant (magnesium hydroxide:aluminum hydroxide = 2.5:1, surface modified with silane coupling agent KH550), 4.5 parts coupling agent (KH550:KH560 = 1:1), 2 parts antioxidant (1010:DLTP = 2:1), 3 parts synergistic ceramicizing agent (talc:mica powder = 1:1, particle size 5-10μm). Intumescent flame retardant tape raw materials: 50 parts base material (glass fiber cloth, 110g / m²), intumescent flame retardant (polyphosphate)... Ammonium:Pentaerythritol:Melamine = 4.5:1.7:1) 42 parts, binder (waterborne polyurethane resin:waterborne epoxy resin = 2:1, solid content 45%) 9 parts, smoke suppressant (ammonium molybdate:nano magnesium hydroxide = 1:1.5, nano magnesium hydroxide particle size 50-100nm) 6 parts, synergistic flame retardant (nano montmorillonite, particle size 20-50nm) 3.5 parts, toughening agent (waterborne acrylic emulsion, solid content 45%) 2 parts, flame retardant and smoke suppressant composite agent (nano zinc oxide:carbon black = 2:1, nano zinc oxide particle size 30-80nm, carbon black particle size 10-30nm) 2.2 parts; armor layer: 304 stainless steel wire, diameter 0.3mm; low smoke halogen-free flame retardant outer sheath: low smoke halogen-free polyolefin composite material (melt index 2.5g / 10min, oxygen index ≥32%).

[0058] Preparation of each functional layer, and preparation of the flame retardant and smoke-suppressing composite agent:

[0059] Raw material pretreatment: Select micron-sized zinc oxide powder with a purity ≥99.5% and carbon black powder with a purity ≥99%. Put the zinc oxide powder into a ball mill and coarsely grind for 30 minutes to obtain fine powder; put the carbon black powder into a 100℃ oven and dry for 1 hour to remove surface adsorbed water.

[0060] Solution preparation: Weigh 3.6 kg of pretreated zinc oxide and 1.8 kg of carbon black at a weight ratio of 2:1, add them to 30 L of deionized water, and add polyethylene glycol 400 dispersant at a weight ratio of 0.5% of the total mass of the mixed powder. Stir for 15 minutes to form a suspension.

[0061] Ultrasonic dispersion: Place the suspension in a 400W ultrasonic dispersion device and disperse for 30 minutes to break up powder agglomerates;

[0062] Coprecipitation reaction: The uniformly dispersed suspension was transferred to a reaction vessel, heated to 75°C, and a 1 mol / L ammonium bicarbonate solution was slowly added dropwise. The pH of the system was adjusted to 8.2, and the reaction was carried out at a constant temperature with stirring for 2 hours to form a zinc salt-carbon black composite precipitate.

[0063] Solid-liquid separation: Place the reaction mixture into a centrifuge and centrifuge at 3000 r / min for 15 minutes to separate the precipitate; wash the precipitate repeatedly with deionized water 4 times until the pH of the washing solution is 7.0 (neutral).

[0064] Calcination activation: The washed precipitate was placed in an oven and dried at 120°C for 4 hours. Then it was transferred to a muffle furnace and heated to 480°C at a rate of 5°C / min under a nitrogen protective atmosphere. The temperature was then kept constant for 2 hours.

[0065] Crushing and sieving: The calcined composite solid is crushed by a high-speed crusher and then passed through a 300-mesh standard sieve to collect the powder that passes through the sieve.

[0066] Preparation of ceramicized silicone rubber composite materials:

[0067] Raw material pretreatment: Place ceramic powder and synergistic ceramicizing agent in a 115℃ oven and dry for 2.5 hours to remove moisture; preheat silicone rubber matrix at 70℃ for 30 minutes to soften the matrix; dry the surface-modified flame retardant at 90℃ for 1 hour; store coupling agent and antioxidant in a sealed container at room temperature and stir well before use.

[0068] Premixing: Place 70 parts of the pretreated silicone rubber matrix into a mixer and stir for 6.5 minutes at a temperature of 95℃ and a speed of 65r / min. Then add 4.5 parts of the complex coupling agent and continue stirring for 4 minutes to make the coupling agent evenly dispersed in the silicone rubber matrix.

[0069] Filler mixing: Add 28 parts ceramic powder, 3 parts synergistic ceramicizing agent, 15 parts modified flame retardant and 2 parts compound antioxidant to the internal mixer in sequence. Maintain the temperature at 110℃ and the speed at 100r / min, and stir for 15 minutes. During this period, open the top plug of the internal mixer to vent once every 3 minutes, and vent for 12 seconds each time to fully integrate the filler with the silicone rubber matrix and form a uniform mixed rubber compound.

[0070] Mixing and homogenization: Transfer the mixed rubber compound to a two-roll mill and pass it through a thin mill 5 times at a temperature of 80℃, with the thickness of each pass controlled at 0.8mm. Then adjust the roller gap to 2.5mm and run the mill for 8 minutes, turning it over multiple times during the process to further improve the uniformity of the rubber compound.

[0071] Cooling and granulation: The homogenized rubber compound is placed in a cooler and cooled to room temperature. Then, it is cut into 4mm particles by a pelletizer, sealed and stored for later use, thus obtaining the ceramicized silicone rubber composite material.

[0072] Preparation of intumescent flame retardant tape: Raw material pretreatment: 42 parts of intumescent flame retardant, 6 parts of smoke suppressant, 3.5 parts of synergistic flame retardant, and 2.2 parts of flame retardant and smoke suppressant composite agent were passed through a 250-mesh sieve and then dried in a vacuum drying oven at 85-95℃ for 3 hours; 50 parts of glass fiber cloth substrate were subjected to plasma treatment (processing power 350W, time 4 minutes) after removing surface impurities with a dust removal device, and then preheated in a 100℃ oven for 10 minutes; 9 parts of binder and 2 parts of toughening agent were mixed evenly in proportion and ultrasonically dispersed for 15 minutes before use;

[0073] Mixing and Pulping: The pretreated intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are placed in a high-speed mixer and dry-mixed at 1200 r / min for 15 minutes to obtain a mixed powder. The mixture of compound binder and toughening agent is slowly added to the mixed powder, and the mixture is continued to be mixed at 800 r / min for 8 minutes. An appropriate amount of deionized water is added according to the viscosity of the slurry to adjust the solid content of the system to 55% to form a paste-like slurry. The slurry is allowed to stand for 8 minutes to eliminate air bubbles, and stirred once every 2 minutes during this period (300 r / min, 30 seconds).

[0074] Double-sided coating: The pretreated substrate is laid flat on the unwinding device of the coating machine. The unwinding tension is adjusted to 4N. A combined coating method of doctor blade and roller coating is adopted. First, the first side (thickness 0.2mm) is coated by doctor blade. After preliminary drying in the pre-drying tunnel (temperature 65℃, time 4 minutes), the second side (thickness 0.2mm) is coated by roller coating to ensure uniform coating.

[0075] Segmented drying: The coated substrate is sent into a continuous drying box and a three-stage drying process is adopted: the first stage temperature is 90℃ and the time is 22 minutes, the second stage temperature is 110℃ and the time is 25 minutes, and the third stage temperature is 130℃ and the time is 15 minutes. The wind speed in the drying box is controlled at 1.5m / s to maintain good ventilation.

[0076] Cooling and cutting: The dried flame-retardant tape is cooled to room temperature by a cooling roller at 28°C, and then cut into strips with a width of 35mm by a slitting machine at a cutting speed of 45r / min. The cutting is assisted by ultrasonic waves to prevent the base material fibers from fuzzing; at the same time, anti-slip textures are pressed on the outer surface of the flame-retardant tape.

[0077] Inspection and storage: The performance of the flame-retardant tape was sampled and tested. Its thickness was 0.45mm, tensile strength was 68N / cm, fire expansion ratio was 25 times, and smoke density level during combustion was 52, which met the requirements. The qualified flame-retardant tape was sealed and stored in a dry and ventilated warehouse with a humidity of 55% for later use.

[0078] Overall cable forming: Insulation coating. After wiping the oxygen-free copper conductor with anhydrous ethanol to remove impurities and drying it, ceramicized silicone rubber composite material particles are added to a 60℃ hot air drying hopper. The material is then coated through a single screw extruder (segmented temperature control 130℃-160℃, speed 40r / min) and a concentric die (concentricity deviation ≤0.03mm). After cooling and shaping in a 25℃ constant temperature water bath, the insulation layer thickness is re-inspected to be 1.0mm (deviation ±0.05mm). After passing the inspection, the cable proceeds to the next process.

[0079] Cable core stranding: Three insulated wires are twisted regularly to the right, with the gaps filled with 0.5mm fiberglass rope that has been dried at 100℃ for 2 hours. The cable core diameter is checked every 50m (deviation ≤0.1mm). After stranding, the cable is fixed with polyester cable ties at 200mm intervals and the length is marked to prevent loosening.

[0080] Flame-retardant insulation layer wrapping: Intumescent flame-retardant tape is wrapped with overlapping layers at a tension of 6N, with the anti-slip texture facing outwards and tightly attached to the cable core, with a final thickness of 0.65mm (deviation ≤0.03mm). After sampling inspection to ensure no missing or skipped wrapping, the cable enters the armoring process.

[0081] Armoring: Stainless steel wire armoring is performed using a 16-spindle high-speed braiding machine, using 304 stainless steel wire (0.3mm in diameter, 120r / min speed, 2N tension per wire) to ensure that the braided layer and the flame-retardant layer are tightly bonded without slippage. Every 100m is tested to ensure there are no broken wires or missing braids, and the surface is flat and smooth.

[0082] Outer sheath coating: Low-smoke halogen-free polyolefin is coated by a twin-screw extruder with a die pressure of 12MPa and a final thickness of 1.5mm (deviation ±0.1mm). After pre-cooling in 30℃ warm water and setting in 20℃ cold water, the insulation performance is tested by a spark tester and it passes the test before proceeding to post-processing.

[0083] Finished product processing and inspection: The cable is wound up with a tension of 15N. After completing all tests such as appearance, size, fire resistance, and flame retardancy, a sealing plug is installed, a label is affixed, and the cable is stored in a dry and ventilated warehouse to obtain the finished product.

[0084] Example 2: Lighting and general socket distribution cables suitable for multi-story residential buildings. Raw material preparation: Conductor: oxygen-free copper wire, single wire diameter 0.18mm, stranded to form a conductor with a cross-sectional area of ​​1.5mm²; ceramicized silicone rubber composite material raw materials are the same as in Example 1; intumescent flame retardant tape raw materials: 40 parts base material, 35 parts intumescent flame retardant, 6 parts binder, 4 parts smoke suppressant, 2 parts synergistic flame retardant, 1 part toughening agent, 1.5 parts flame retardant and smoke suppressant composite agent; armor layer: 304 stainless steel wire, diameter 0.25mm; low smoke halogen-free flame retardant outer sheath: low smoke halogen-free polyolefin composite material.

[0085] Preparation of each functional layer and preparation of flame retardant and smoke suppressant composite: Raw material pretreatment: Select nano-grade zinc oxide powder with a purity ≥99.5% and conductive carbon black powder with a purity ≥99%. Put the zinc oxide powder into a planetary ball mill, add zirconium oxide ball milling media, and grind at a speed of 200 r / min for 45 minutes to obtain uniform powder; put the carbon black powder into a 110℃ oven to dry for 1.5 hours to completely remove surface adsorbed water and impurities;

[0086] Solution preparation: Weigh 2.0 kg of pretreated zinc oxide and 1.0 kg of carbon black at a weight ratio of 2:1, add them to 25 L of deionized water, and add sodium dodecylbenzene sulfonate dispersant at a weight ratio of 0.8% of the total mass of the mixed powder. Turn on the high-speed stirrer and stir at 800 r / min for 20 minutes to form a uniform suspension.

[0087] Ultrasonic dispersion: The suspension is placed in a 600W ultrasonic dispersion device and dispersed at a constant temperature of 30℃ for 40 minutes to further break up powder agglomerates and ensure uniform powder dispersion.

[0088] Coprecipitation reaction: The uniformly dispersed suspension was transferred to a stainless steel reactor and heated to 75°C. A 1.2 mol / L ammonium bicarbonate solution was slowly added dropwise at a rate of 1.5 mL / min. The pH value of the system was monitored in real time until the pH value reached 8.2. Then the reaction was stirred at a constant temperature for 2.5 hours to form a zinc salt-carbon black composite precipitate.

[0089] Solid-liquid separation: The reaction mixture was placed in a horizontal screw centrifuge and centrifuged at 4000 r / min for 20 minutes to separate the precipitate; the precipitate was washed repeatedly with deionized water 4 times until the pH of the washing solution was 7.0, and then washed once with anhydrous ethanol to remove residual water.

[0090] Calcination activation: The washed precipitate was placed in a vacuum oven and dried at 130°C for 5 hours. Then it was transferred to a tube furnace and heated to 460°C at a rate of 3°C / min under an argon protective atmosphere, and calcined at a constant temperature for 2.5 hours.

[0091] Crushing and sieving: The calcined composite solid is crushed by an ultra-fine pulverizer and then passed through a 400-mesh standard sieve to collect the powder that passes through the sieve.

[0092] Finished product storage: The sieved composite powder is placed into a vacuum-sealed moisture-proof packaging container and stored in a dry and ventilated place for later use, thus obtaining the flame retardant and smoke-suppressing composite agent.

[0093] The preparation process of the ceramicized silicone rubber composite material is the same as that in Example 1.

[0094] Preparation of intumescent flame retardant tape: Raw material pretreatment: 35 parts of intumescent flame retardant, 4 parts of smoke suppressant, 2 parts of synergistic flame retardant, and 1.5 parts of flame retardant and smoke suppressant composite agent were passed through a 300-mesh sieve and then placed in a vacuum drying oven at 90℃ for 3.5 hours to remove moisture and impurities; 40 parts of glass fiber cloth substrate were subjected to high-pressure airflow dust removal equipment to remove surface impurities, then subjected to ultraviolet light modification treatment, and then placed in a 105℃ oven for preheating for 15 minutes; 6 parts of binder and 1 part of toughening agent were mixed evenly in proportion, and 0.5% of defoamer was added to the total mass of the mixture. Before use, the mixture was ultrasonically dispersed for 20 minutes.

[0095] Mixing and pulping: The pretreated intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are placed in a double planetary mixer and dry-mixed for 15 minutes at 1200 r / min to obtain a uniformly mixed powder. The mixture of compound binder, toughening agent, and defoamer is slowly added to the mixed powder, and the mixture is kept at 800 r / min for 8 minutes. An appropriate amount of deionized water is added according to the viscosity of the slurry to adjust the solid content of the system to 48% to form a uniform paste slurry. The slurry is placed in a vacuum degassing tank and degassed for 10 minutes at a pressure of -0.08 MPa to completely eliminate air bubbles inside the slurry.

[0096] Double-sided coating: The pre-treated substrate is laid flat on the unwinding device of the high-precision coating machine, the unwinding tension is adjusted to 3.5N, and the slit extrusion coating method is used. The first side is coated first, and after preliminary drying in the pre-drying tunnel, the second side is coated. During the coating process, the substrate temperature is monitored in real time by an infrared thermometer to ensure uniform coating.

[0097] Segmented drying: The coated substrate is sent into a continuous hot air drying box and a four-stage drying process is adopted: the first stage temperature is 80℃ and the time is 15 minutes, the second stage temperature is 95℃ and the time is 20 minutes, the third stage temperature is 110℃ and the time is 25 minutes, and the fourth stage temperature is 125℃ and the time is 10 minutes. The air velocity in the drying box is controlled at 1.0m / s to maintain good ventilation and avoid coating cracking.

[0098] Cooling and cutting: The dried flame-retardant tape is cooled to room temperature by a constant temperature cooling roller at 25℃, and then cut into 20mm wide strips by a high-precision slitting machine at a cutting speed of 35r / min. The cutting blade is made of diamond blade to prevent the base material fibers from fuzzing. At the same time, a diamond anti-slip texture is pressed on the outer surface of the flame-retardant tape by an embossing roller with a texture depth of 0.1mm.

[0099] Inspection and storage: The performance of the flame-retardant tape was sampled and tested. Its thickness was 0.35mm, tensile strength was 62N / cm, fire expansion ratio was 18 times, and smoke density level during combustion was 60, which met the requirements. The qualified flame-retardant tape was sealed and stored in a dry and ventilated warehouse with a humidity of 50% for later use.

[0100] The technical process for integral cable forming in this embodiment is the same as that in Embodiment 1.

[0101] Example 3: Application in industrial production equipment power distribution scenarios. Raw material preparation: The conductor is oxygen-free copper wire with a single wire diameter of 0.22mm, stranded to form a conductor with a cross-sectional area of ​​4.0mm²; the raw material of the ceramicized silicone rubber composite material is the same as that in Example 1; the raw material of the intumescent flame retardant tape is: 60 parts of base material, 50 parts of intumescent flame retardant, 12 parts of binder, 9 parts of smoke suppressant, 5 parts of synergistic flame retardant, 3 parts of toughening agent, and 3 parts of flame retardant and smoke suppressant composite agent; the armor layer is made of 304 stainless steel wire with a diameter of 0.35mm; the low-smoke halogen-free flame retardant outer sheath is made of low-smoke halogen-free polyolefin composite material.

[0102] Preparation of flame retardant and smoke suppressant composite agent: Raw material pretreatment: Select nano-grade zinc oxide powder with a purity ≥99.8% and superconducting carbon black powder with a purity ≥99.5%. Mix the zinc oxide powder and carbon black powder in a weight ratio of 2:1 in advance, and put them into an air jet mill to pulverize for 30 minutes to obtain mixed initial powder; put the mixed initial powder into a vacuum oven at 120℃ and dry for 2 hours to completely remove surface adsorbed water and volatile impurities;

[0103] Solution preparation: Weigh 6.0 kg of the pretreated mixed powder and add it to 45 L of deionized water. At the same time, add 1.0% of the total mass of the mixed powder as dispersant, polymethyl methacrylate. Turn on the high-speed shear emulsifier and stir at 1200 r / min for 30 minutes to form a stable suspension.

[0104] Ultrasonic dispersion: The suspension is placed in an 800W ultrasonic dispersion device and dispersed for 50 minutes at a constant temperature of 35℃. The ultrasonic dispersion method combined with stirring is used to ensure that the powder is completely dispersed without agglomeration.

[0105] Coprecipitation reaction: The uniformly dispersed suspension was transferred to a high-pressure reactor, heated to 85°C, and the pressure was maintained at 0.3 MPa. A 1.5 mol / L ammonium bicarbonate solution was slowly added dropwise at a rate of 2.0 mL / min. The pH of the system was adjusted to 8.8. The reaction was carried out under constant temperature and pressure with stirring for 3 hours to form a zinc salt-carbon black composite precipitate.

[0106] Solid-liquid separation: The reaction mixture was placed in a disc centrifuge and centrifuged at 5000 r / min for 25 minutes to separate the precipitate; the precipitate was washed repeatedly with deionized water 5 times until the pH of the washing solution was 7.0 (neutral), and then washed twice with isopropanol to improve the drying efficiency of the precipitate.

[0107] Calcination activation: The washed precipitate was placed in a freeze dryer and dried for 8 hours at -50℃ and vacuum degree ≤10Pa. Then it was transferred to a tube furnace and heated to 520℃ at a heating rate of 4℃ / min under a protective atmosphere of nitrogen and argon. The temperature was then kept constant for 3 hours.

[0108] Crushing and sieving: After the calcined composite solid is crushed twice by an air jet mill, it is passed through a 500-mesh standard sieve and the powder under the sieve is collected.

[0109] Finished product storage: The sieved composite powder is placed into a sealed packaging container protected by inert gas and stored in a dry, cool, and ventilated place for later use, thus obtaining the flame retardant and smoke suppressant composite agent.

[0110] Preparation of intumescent flame retardant tape: Raw material pretreatment: 50 parts of intumescent flame retardant, 9 parts of smoke suppressant, 5 parts of synergistic flame retardant, and 3 parts of flame retardant and smoke suppressant composite agent were passed through a 350-mesh sieve and then placed in a vacuum drying oven at 100℃ for 4 hours to completely remove moisture and impurities; 60 parts of glass fiber cloth substrate were plasma treated and then coated with silane coupling agent, and preheated in an oven at 110℃ for 20 minutes; 12 parts of binder and 3 parts of toughening agent were mixed evenly in proportion, and 0.8% of defoamer was added to the total mass of the mixture. The mixture was ultrasonically dispersed for 25 minutes before use.

[0111] Mixing and pulping: The pretreated intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are placed in a high-speed mixer and dry-mixed at 1800 r / min for 20 minutes to obtain a uniformly mixed powder. The mixture of compound binder, toughening agent, and defoamer is slowly added to the mixed powder, and the mixture is continued to be mixed at 1000 r / min for 12 minutes. An appropriate amount of deionized water is added according to the viscosity of the slurry to adjust the solid content of the system to 68% to form a uniform paste slurry. The slurry is placed in a vacuum degassing tank and degassed at a pressure of -0.09 MPa for 15 minutes to completely eliminate air bubbles inside the slurry.

[0112] Double-sided coating: The pre-treated substrate is laid flat on the unwinding device of the high-precision coating machine. The unwinding tension is adjusted to 5.5N. A combined coating method of doctor blade and roller coating is adopted. First, the first side is coated by doctor blade. After preliminary drying in the pre-drying tunnel, the second side is coated by roller coating. During the coating process, the coating thickness is monitored in real time by an online thickness monitoring instrument to ensure uniform coating.

[0113] Segmented drying: The coated substrate is sent into a continuous hot air drying box and a four-stage drying process is adopted: the first stage temperature is 90℃ and the time is 20 minutes, the second stage temperature is 105℃ and the time is 25 minutes, the third stage temperature is 120℃ and the time is 30 minutes, and the fourth stage temperature is 140℃ and the time is 15 minutes. The air velocity in the drying box is controlled at 2.0m / s to maintain good ventilation and ensure that the coating is completely cured.

[0114] Cooling and Cutting: After drying, the flame-retardant tape is cooled to room temperature by a constant temperature cooling roller at 30℃. It is then cut into 50mm wide strips by a high-precision slitting machine at a cutting speed of 55r / min. The cutting blade is made of diamond and equipped with an electrostatic dust removal device to prevent the substrate fibers from fuzzing and dust from adsorbing. At the same time, a trapezoidal anti-slip texture is pressed on the outer surface of the flame-retardant tape by an embossing roller with a texture depth of 0.15mm to improve the adhesion with the armor layer.

[0115] Inspection and storage: The performance of the flame-retardant tape was sampled and tested. Its thickness was 0.55mm, tensile strength was 75N / cm, fire expansion ratio was 30 times, and smoke density level during combustion was 50, which met the requirements. The qualified flame-retardant tape was sealed and stored in a dry and ventilated warehouse with a humidity of 60% for later use.

[0116] The technical process for integral cable forming in this embodiment is the same as that in Embodiment 1.

[0117] Comparative Example 1: Traditional PVC insulated flame-retardant cable, using traditional stranding process to prepare copper conductors, without any special pretreatment after stranding; using traditional PVC resin as insulation material, melt-coated in a single-screw extruder with temperature control within a single temperature range, and naturally cooled and shaped; multiple insulated wires are randomly stranded, with gaps filled with ordinary polypropylene filler rope, maintaining stability only through stranding tension; traditional flame-retardant tape is manually wrapped, with no precise control or online monitoring of tension and overlap rate; ordinary PVC sheath material is used for extrusion coating, and naturally cooled by air; the finished product is directly wound up, with only a simple visual inspection before winding, without systematic performance testing.

[0118] Comparative Example 2: Traditional rubber-insulated unarmored cable: using ordinary natural rubber as insulation material, it is mixed in an open rubber mixing mill and then traditionally extruded and coated, with temperature controlled by experience; multiple insulated conductors are simply twisted to the left, with no fixed pitch design and no gap filling; the flame-retardant isolation layer and armor layer are omitted, and ordinary rubber sheath material is directly extruded and coated onto the cable core without concentricity control; the finished product is naturally cooled and wound up, with no precise tension control.

[0119] It should be noted that the parameter performance table of the fire-resistant and flame-retardant low-voltage power cable prepared through the above embodiments and comparative examples is as follows:

[0120] Table 1: Performance Parameters of Examples and Comparative Examples

[0121] Comparison Projects Example 1 Implementation 2 Implementation Three Comparative Example 1 Comparative Example 2 Flame retardant properties (self-extinguishing time / s) 16 20 18 60 90 Smoke suppression performance (smoke density rating, SDR) 30 32 35 80 90 Tensile strength (MPa) 16 14 13 8 6

[0122] Specifically, in terms of flame retardant performance (self-extinguishing time / s): the example group (16-20s) is far superior to the comparative group (60-90s). Among them, Example 1 performed best (16s), Example 3 performed best (18s), and Example 2 was slightly weaker (20s). The self-extinguishing time of all three was controlled within 20s, indicating that the cable has excellent flame retardant properties. After the open flame is removed, it can quickly stop the combustion and inhibit the continued spread of the flame, which meets the stringent requirements for the flame retardancy of cables in the power distribution scenario of industrial production equipment. In contrast, the self-extinguishing times of Comparative Examples 1 and 2 are 60s and 90s, respectively. Even after the open flame is removed, it still takes a long time to extinguish, and the risk of flame spread is high, which cannot meet the safety requirements of complex industrial environments.

[0123] Specifically, in terms of smoke suppression performance (smoke density level SDR): the example group (30-35) was significantly better than the comparative group (80-90). Example 1 had the best smoke suppression effect (30), followed by Example 2 (32) and Example 3 (35), but all were at a low smoke density level. In the event of a fire, this could reduce smoke release, reduce obstruction of vision and the harm of toxic fumes, and buy time for the evacuation of personnel and emergency response of equipment at the industrial site. The smoke density level of the comparative group was much higher than that of the examples, which could easily form a dense smoke environment in the fire, exacerbating the risk of casualties and property damage.

[0124] Specifically, in terms of tensile strength (MPa): the strength of the example group (13-16MPa) was significantly higher than that of the comparative group (6-8MPa). Example 1 had the highest tensile strength (16MPa), exhibiting the strongest tensile and breakage resistance. Although Example 2 (14MPa) and Example 3 (13MPa) showed slight decreases, they still met the mechanical requirements of cable laying and dragging in industrial scenarios. The tensile strength of the comparative group was only 40%-50% of that of the example group. In environments with frequent start-ups and shutdowns and vibrations of industrial equipment, it was prone to problems such as sheath cracking and insulation damage, affecting power supply stability.

[0125] In summary, the aforementioned cables exhibit improvements in flame retardancy, fire resistance, smoke suppression, and mechanical properties, fully meeting the stringent safety and stability requirements of power distribution in industrial production equipment. In contrast, the comparative cables, manufactured using traditional processes, have significant performance limitations and struggle to meet the demands of complex industrial environments.

[0126] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fire-resistant and flame-retardant low-voltage power cable, characterized in that, It includes, from the inside out, a conductor (1), a fire-resistant insulation layer (2), a flame-retardant isolation layer (3), an armor layer (4), and a low-smoke halogen-free flame-retardant outer sheath (5); The fire-resistant insulation layer (2) tightly covers the outside of the conductor (1). The fire-resistant insulation layer (2) is a ceramicized silicone rubber composite material. The ceramicized silicone rubber composite material can form a dense ceramic layer at a high temperature of 600-1000℃. Multiple conductors (1) covered with fire-resistant insulation layer (2) are twisted together to form a cable core. The flame-retardant isolation layer (3) is tightly wrapped around the outside of the cable core. The flame-retardant isolation layer (3) is an intumescent flame-retardant strip. The armor layer (4) is fitted over the flame-retardant isolation layer (3), and the armor layer (4) is a stainless steel wire braided structure; The low-smoke halogen-free flame-retardant outer sheath (5) covers the outside of the armor layer (4), and the low-smoke halogen-free flame-retardant outer sheath (5) is a low-smoke halogen-free polyolefin composite material.

2. The fire-resistant and flame-retardant low-voltage power cable according to claim 1, characterized in that, The ceramicized silicone rubber composite material is composed of the following raw materials in the indicated weight ratios: 60-80 parts of silicone rubber matrix, 25-32 parts of ceramic powder, 12-18 parts of flame retardant, 3-6 parts of coupling agent, 1-3 parts of antioxidant, and 2-4 parts of synergistic ceramic agent; The ceramic powder is a mixture of kaolin and silicon dioxide, with a weight ratio of 1.2:1 to 2.2:

1. The flame retardant is a compound of magnesium hydroxide and aluminum hydroxide in a weight ratio of 1.5:1 to 3.5:2, and both have undergone surface modification treatment. The coupling agent is a compound of silane coupling agents KH550 and KH560 in a weight ratio of 1:1; The antioxidant is a compound of antioxidant 1010 and auxiliary antioxidant DLTP in a weight ratio of 2:

1. The synergistic ceramic-forming agent is a compound of talc powder and mica powder in a weight ratio of 1:1, with a particle size of 5-10 μm.

3. The fire-resistant and flame-retardant low-voltage power cable according to claim 2, characterized in that, The preparation process of ceramicized silicone rubber composite material includes the following steps: Raw material pretreatment: Place ceramic powder and synergistic ceramicizing agent in an oven at 110-120℃ and dry for 2-3 hours to remove moisture; preheat silicone rubber matrix at 60-80℃ for 30 minutes to soften the matrix; after surface modification treatment, flame retardant is dried at 90℃ for 1 hour; coupling agent and antioxidant are stored in a sealed container at room temperature and stirred evenly before use. Premixing: Place the pretreated silicone rubber matrix into a mixer and stir for 5 to 8 minutes at a temperature of 90 to 100°C and a speed of 50 to 80 r / min. Then add the complex coupling agent and continue stirring for 3 to 5 minutes to ensure that the coupling agent is evenly dispersed in the silicone rubber matrix. Filler mixing: Pretreated ceramic powder, synergistic ceramicizing agent, modified flame retardant and compound antioxidant are added to the internal mixer in sequence. During this process, the top plug of the internal mixer is opened once every 3 minutes to exhaust the air, so that the filler and silicone rubber matrix are fully integrated to form a uniform mixed rubber compound. Mixing and homogenization: Transfer the mixed rubber compound to a two-roll mill and pass it through a thin mill 4 to 6 times at a temperature of 75 to 85°C. The thickness of each pass should be controlled at 0.5 to 1 mm. Then adjust the roller gap to 2 to 3 mm and run the mill for 6 to 10 minutes. During this period, the mill is turned over multiple times to further improve the uniformity of the rubber compound. Cooling and granulation: The homogenized rubber compound is placed in a cooler and cooled to room temperature. Then, it is cut into granules with a particle size of 3-5 mm by a pelletizer, sealed and stored for later use, thus obtaining ceramicized silicone rubber composite material.

4. The fire-resistant and flame-retardant low-voltage power cable according to claim 1, characterized in that, Intumescent flame-retardant tape is composed of the following raw materials in the indicated weight ratios: 40-60 parts of base material, 35-50 parts of intumescent flame retardant, 6-12 parts of binder, 4-9 parts of smoke suppressant, 2-5 parts of synergistic flame retardant, and 1-3 parts of toughening agent; The substrate is made of glass fiber cloth with a basis weight of 90-130 g / m², and the surface is treated with plasma. The intumescent flame retardant is a compound of ammonium polyphosphate, pentaerythritol and melamine, with a weight ratio of 3.5:1.2:1 to 5.5:2.2:

1. The adhesive is a blend of waterborne polyurethane resin and waterborne epoxy resin in a weight ratio of 2:1, with a solid content of 35% to 55%. The smoke suppressant is a compound of ammonium molybdate and nano-magnesium hydroxide in a weight ratio of 1:1.5, and the nano-magnesium hydroxide has a particle size of 50-100 nm. The synergistic flame retardant is nano-montmorillonite with a particle size of 20–50 nm; the toughening agent is a water-based acrylic emulsion with a solid content of 40%–50%. The flame retardant and smoke suppressant composite is a mixture of nano zinc oxide and carbon black in a weight ratio of 2:

1. The nano zinc oxide has a particle size of 30-80 nm, and the carbon black has a particle size of 10-30 nm.

5. A fire-resistant and flame-retardant low-voltage power cable according to claim 4, characterized in that, The preparation process of intumescent flame-retardant tape includes the following steps: Raw material pretreatment: The intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are sieved separately and then dried in a vacuum drying oven; the substrate is treated with plasma after surface impurities are removed by dust removal equipment; the binder and toughening agent are mixed evenly in proportion and ultrasonically dispersed for 15 minutes before use. Mixing and pulping: The pretreated intumescent flame retardant, smoke suppressant, synergistic flame retardant, and flame retardant and smoke suppressant composite agent are put into a high-speed mixer to obtain a mixed powder; the mixture of compound binder and toughening agent is slowly added to the mixed powder, and mixing continues. Deionized water is added according to the viscosity of the slurry to adjust the solid content of the system to 45% to 65% to form a paste slurry. Let it stand for 8 minutes to eliminate air bubbles. Double-sided coating: The pretreated substrate is laid flat on the unwinding device of the coating machine. The unwinding tension is adjusted to 3-5N. A combined coating method of doctor blade and roller coating is adopted. First, the first side is coated by doctor blade. After preliminary drying in the pre-drying tunnel, the second side is coated by roller coating to ensure uniform coating. Segmented drying: The coated substrate is sent into a continuous drying chamber and a three-stage drying process is adopted: the first stage temperature is 85-95℃ and the time is 18-25 minutes; the second stage temperature is 105-115℃ and the time is 22-28 minutes; the third stage temperature is 125-135℃ and the time is 12-18 minutes. The air velocity in the drying chamber is controlled at 1.2-1.8m / s to maintain good ventilation. Cooling and cutting: The dried flame-retardant tape is cooled to room temperature by cooling rollers at a temperature of 25-30℃, and then cut into strip structures with a width of 20-50mm by a slitting machine at a cutting speed of 35-55r / min. The cutting is assisted by ultrasonic cutting to prevent the substrate fibers from fuzzing. Inspection and storage: Sampling inspection ensures that the product thickness is 0.35-0.55mm, the tensile strength is not less than 60N / cm, the expansion ratio when exposed to fire is 18-30 times, and the smoke density level during combustion is ≤65. After passing the inspection, the product is sealed and stored in a dry and ventilated warehouse with a humidity of 50%-60%.

6. The fire-resistant and flame-retardant low-voltage power cable according to claim 5, characterized in that: The preparation process of the flame retardant and smoke suppressant composite agent includes the following steps: Raw material pretreatment: Select zinc oxide powder and carbon black powder. Put the zinc oxide powder into a ball mill and coarsely grind for 30 minutes to obtain fine powder; dry the carbon black powder in a 100℃ oven for 1 hour to remove surface adsorbed water. Solution preparation: Weigh the pretreated zinc oxide and carbon black at a weight ratio of 2:1, add them to deionized water, and add polyethylene glycol 400 dispersant accounting for 0.5% of the total mass of the mixed powder. Stir to form a suspension. Ultrasonic dispersion: The suspension is placed in an ultrasonic dispersion device to disperse the powder agglomerates; Coprecipitation reaction: The uniformly dispersed suspension is heated to 70-80℃, and a 1mol / L ammonium bicarbonate solution is slowly added dropwise to adjust the pH of the system to 8.0-8.

5. The mixture is stirred at a constant temperature for 2 hours to form a zinc salt-carbon black composite precipitate. Solid-liquid separation: The mixture after the reaction is placed in a centrifuge to separate the precipitate. The precipitate is washed repeatedly with deionized water 3 to 4 times until the pH of the washing solution is neutral. Calcination activation: After the washed precipitate is dried in an oven for 4 hours, it is transferred to a muffle furnace and heated to 450-500℃ at a heating rate of 5℃ / min under a nitrogen protective atmosphere, and then calcined at a constant temperature for 2 hours. Crushing and sieving: After the calcined composite solid is crushed by a high-speed crusher, it is passed through a standard sieve and the powder under the sieve is collected; Finished product storage: Pack the sieved composite powder into a sealed, moisture-proof container and store it in a dry, ventilated place for later use.

7. The fire-resistant and flame-retardant low-voltage power cable according to claim 1, characterized in that, The thickness of the fire-resistant insulation layer (2) is 0.8 to 1.2 mm, the wrapping overlap rate of the flame-retardant isolation layer (3) is 25% to 35%, and the thickness of the formed flame-retardant isolation layer (3) is 0.5 to 0.8 mm.

8. The fire-resistant and flame-retardant low-voltage power cable according to claim 1, characterized in that, The outer surface of the flame-retardant isolation layer (3) is provided with anti-slip texture, which is used to enhance the friction between the flame-retardant isolation layer (3) and the armor layer (4).

Images