Flexible b1 class flame retardant power cord and manufacturing method

Abstract

The application relates to the field of cable material processing, and particularly discloses a soft B1-grade flame-retardant power line and a manufacturing method, the soft B1-grade flame-retardant power line comprises a conductor and an insulation layer; the insulation layer is made of an insulation material, and the insulation material comprises the following raw materials in parts by weight: EVA 40-60 parts, LLDPE 20-40 parts, POE 15-25 parts, halogen-free flame retardant 130-150 parts, phosphorus-nitrogen synergist 15-25 parts, interface modifier 7-12 parts, filler 4-11 parts, antioxidant 0.5-0.8 parts and lubricant 0.8-2.2 parts; the manufacturing method is as follows: bare copper monofilament is twisted to prepare the conductor; the conductor surface is extruded and coated with the insulation material to form the insulation layer, and the finished product power line is obtained; the power line has the advantages of B1-grade flame-retardant grade, softness with a Shore A hardness not higher than 92HA, and ROHS 2.0 and REACH double environmental protection compliance requirements.

Description

Technical Field

[0001] This application relates to the field of cable material processing, and more specifically, it relates to a flexible B1-grade flame-retardant power cord and a method for manufacturing it. Background Technology

[0002] Power cords are essential components for transmitting electrical energy between electrical equipment and power supply systems. They are widely used in household appliances, industrial equipment, building electrical systems, and data centers. With the continuous improvement of building fire protection standards and the increasingly stringent international environmental regulations, the market has placed higher demands on the flame-retardant performance and environmental compliance of power cords.

[0003] In terms of flame retardant performance, the current national standard GB31247 classifies the combustion performance of cables into four levels: A, B1, B2, and B3. Among them, the B1 level requires the cable to have high flame retardant performance, and the oxygen index must reach more than 36%. To achieve this flame retardant level, the traditional technical route usually adopts halogen-containing flame retardant systems (such as chlorinated paraffin, bromine flame retardants, etc.) or fills a large amount of inorganic flame retardants (such as aluminum hydroxide, magnesium hydroxide, etc.) in halogen-free systems. However, both of the above solutions have obvious drawbacks: halogenated flame retardant systems release large amounts of toxic hydrogen halide gas and dense smoke when burning, endangering personnel evacuation safety, and contain harmful substances such as lead, cadmium, and hexavalent chromium, which do not meet the environmental compliance requirements of the EU RoHS 2.0 Directive (2011 / 65 / EU) and REACH Regulation (EC1907 / 2006); while halogen-free systems can solve environmental problems by filling a large amount of inorganic flame retardants, the addition of a large amount of filler will significantly increase the Shore A hardness of the insulation material, resulting in a decrease in the overall flexibility of the power cord, making installation and laying difficult, and making it difficult to meet the flexibility requirement of Shore A hardness not exceeding 92HA.

[0004] Regarding conductor structure, existing power cord products lack sufficient research on parameter optimization of multi-strand filament stranded structures. The systematic design of conductor filament diameter, number of strands, and stranding method lacks standards, affecting the overall flexibility of the conductor.

[0005] The prior art includes a Chinese invention patent with publication number CN114188085B, which discloses a multi-core flexible mineral-insulated fire-resistant cable with a five-layer composite structure. The mineral insulation layer contains halogen-containing substances such as chlorinated paraffin, which does not meet RoHS 2.0 environmental requirements, and its fire-resistant performance is fundamentally different from the B1-level flame-retardant power cable in this case. A Chinese invention patent application with publication number CN109448909A discloses an ultra-high suspended flame-retardant and fire-resistant high-voltage power cable with a multi-layer composite structure, emphasizing high tensile strength and super fire resistance, which is significantly different from the product positioning of the low-voltage flexible power cable in this case. A Chinese invention patent application with publication number CN105719728A discloses a multi-core flame-retardant flexible cable for communication power supplies with a seven-layer composite structure, emphasizing super fire resistance at 850-1000℃, but does not involve quantitative indicators for B1-level flame retardancy or RoHS 2.0 / REACH compliance requirements.

[0006] Therefore, how to manufacture a new power cord that simultaneously possesses a B1 flame retardant rating, a Shore A hardness not exceeding 92HA, and the advantages of meeting both RoHS 2.0 and REACH environmental compliance requirements is an urgent problem to be solved. Summary of the Invention

[0007] In order to prepare a new power cord that has the advantages of having a B1 flame retardant rating, a Shore A hardness of no more than 92HA, and compliance with both RoHS 2.0 and REACH environmental protection requirements, this application provides a flexible B1 flame retardant power cord and a manufacturing method thereof.

[0008] In a first aspect, this application provides a flexible B1-grade flame-retardant power cord, employing the following technical solution: A flexible B1-grade flame-retardant power cord includes a conductor and an insulation layer. The insulation layer is made of an insulating material comprising the following raw materials in parts by weight: 40-60 parts EVA, 20-40 parts LLDPE, 15-25 parts POE, 130-150 parts halogen-free flame retardant, 15-25 parts phosphorus-nitrogen synergist, 7-12 parts interface modifier, 4-11 parts filler, 0.5-0.8 parts antioxidant, and 0.8-2.2 parts lubricant.

[0009] By adopting the above technical solution, EVA, LLDPE and POE are combined. EVA is used as the main elastic matrix to provide flexibility and flame retardancy synergy. The high elasticity and flexibility of POE improve the low temperature impact resistance and elongation of the power cord, thereby improving the flexibility of the insulation material. LLDPE can improve the tensile strength and abrasion resistance of the insulation layer, further ensuring the strength and flexibility of the insulation material, so that the power cord has the flexibility of Shore A hardness not exceeding 92HA.

[0010] The combination of halogen-free flame retardants and phosphorus-nitrogen synergists further enhances the flame retardancy of the power cord. Combined with fillers, it further improves the strength and flame retardant effect, enabling the power layer to achieve a B1 flame retardancy rating. Furthermore, the halogen-free flame retardant is environmentally friendly, meeting both RoHS 2.0 and REACH environmental compliance requirements.

[0011] Preferably, the halogen-free flame retardant comprises 80-90 parts of magnesium hydroxide and 50-60 parts of aluminum hydroxide, wherein the magnesium hydroxide is surface-treated with stearic acid and the aluminum hydroxide is surface-treated with aluminate.

[0012] By adopting the above technical solutions, magnesium hydroxide can absorb heat and decompose to release water, diluting flammable gases, while aluminum hydroxide can form an alumina ceramic insulation layer, further achieving a flame-retardant effect. Magnesium hydroxide undergoes stearic acid surface treatment, and aluminum hydroxide undergoes aluminate ester surface treatment, which enhances the compatibility and bonding of magnesium hydroxide and aluminum hydroxide with EVA, LLDPE, and POE, avoiding excessive degradation of the mechanical properties of the flame-retardant layer due to the addition of large amounts of flame retardants, and ensuring the mechanical properties of the insulation layer.

[0013] Magnesium hydroxide has a decomposition temperature of approximately 340℃, which is higher than that of aluminum hydroxide. This makes it more suitable for the temperature requirements of polymer processing. It does not decompose prematurely during processing, thus not affecting material properties. Furthermore, it can continue to decompose and absorb heat at higher combustion temperatures, improving the high-temperature flame-retardant stability of the material. Aluminum hydroxide has a decomposition temperature of 190–230℃. It can decompose and absorb heat in the initial stage of combustion, inhibiting the material's temperature rise. It can play a role in preventing the spread of fire in the early stages of a fire. In addition, aluminum hydroxide can significantly slow down the thermal decomposition of polyolefin (EVA / LLDPE) matrix, ensuring the insulation of the insulation layer while maintaining high strength and flame retardancy.

[0014] Preferably, the phosphorus-nitrogen synergist comprises 12-18 parts of ammonium polyphosphate and 3-7 parts of melamine cyanurate.

[0015] By adopting the above technical solution, ammonium polyphosphate will gradually degrade to produce phosphoric acid during combustion, which catalyzes the dehydration and carbonization of the polyolefin matrix material, promotes the formation of an intumescent barrier carbon layer, isolates oxygen and heat conduction, inhibits dripping, and prevents further combustion of the internal matrix. Moreover, ammonium polyphosphate has good compatibility with the polyolefin matrix and is not prone to excessive damage to the mechanical and insulating properties of the insulation layer. Melamine cyanurate, as a nitrogen source, decomposes upon heating to release non-flammable gases such as ammonia and nitrogen, which not only dilutes the oxygen concentration in the combustion zone but also carries away some heat, synergistically forming an intumescent carbon layer with ammonium polyphosphate, controlling dripping while improving flame retardancy.

[0016] Preferably, the interface modifier comprises 6-10 parts maleic anhydride-grafted POE and 1-2 parts silane coupling agent KH-550.

[0017] By adopting the above technical solutions, maleic anhydride grafted POE can improve the compatibility and connection between magnesium hydroxide, aluminum hydroxide and EVA and LLDPE, increase the structural density and stability of the insulation layer, and, combined with its own elasticity, improve the flexibility and strength of the insulation layer, minimizing the risk of cracking and brittleness caused by excessive addition of inorganic fillers, thus ensuring the service life of the insulation layer. Meanwhile, the silane coupling agent KH-550 contains ethoxy and amino groups, which can form chemical bonds at the interface between inorganic fillers and organic polymers, enhancing the interfacial bonding force and further ensuring the strength and flexibility of the insulation layer.

[0018] Preferably, the lubricant comprises 0.6-1.4 parts calcium stearate and 0.2-0.8 parts polyethylene wax.

[0019] By adopting the above technical solution, calcium stearate and polyethylene wax are combined. Calcium stearate can reduce the internal friction of polyolefin molecular chains and improve melt flowability, while polyethylene wax can promote the dispersion effect of halogen-free flame retardants, phosphorus-nitrogen synergists and fillers, and ensure dispersion uniformity, thereby giving the insulating material the advantages of good flexibility and high strength.

[0020] Preferably, the conductor is made of 56-119 bare copper monofilaments twisted together, the diameter of the copper monofilaments is 0.3-0.4 mm, and the interface agent is 4-16 mm thick. 2 .

[0021] By adopting the above technical solutions, the flexibility of the conductor is greatly improved after multiple strands of fine monofilaments are twisted together, making it easier to bend and solving the problem of large cross-sectional area conductors being difficult to bend and lay. Compared with solid wires of the same cross-section, the stranded structure increases the total surface area of ​​the conductor, reduces power loss, and has better conductivity. At the same time, the stranded structure has higher tensile and bending resistance, higher reliability, and a longer service life.

[0022] Preferably, the filler comprises 2-5 parts nano-silica and 2-6 parts zinc borate.

[0023] By adopting the above technical solutions, the filling effect of nano-silica combined with the filling properties of zinc borate gives the insulation layer high strength and good flexibility. Nano-silica can block heat transfer, slow down the thermal decomposition of the polyolefin matrix, and inhibit combustion. Nano-silica can also enhance the char layer structure of the intumescent flame retardant system, improve the thermal stability and mechanical strength of the char layer, and ensure the flame retardant effect of the char layer. Zinc borate melts and absorbs heat at high temperatures, while releasing water of crystallization, lowering the temperature and isolating heat. Zinc borate can also synergistically catalyze the dehydration of the polyolefin matrix into char with phosphorus and nitrogen synergists, while promoting the formation of a denser intumescent char layer. In the condensed phase, it can promote the formation of hard heat-insulating residue, effectively inhibit the generation of molten droplets during the combustion process, avoid secondary fires caused by molten droplets, and ensure the flame retardant effect of the flame retardant layer.

[0024] Preferably, the zinc borate is a loaded zinc borate, which is obtained by treating zinc borate particles with a branched polyethyleneimine solution.

[0025] By adopting the above technical solution, branched polyethyleneimine, a high-molecular-weight cationic polymer, can form steric hindrance on the surface of zinc borate particles, preventing the aggregation of zinc borate particles and allowing them to be uniformly dispersed in the EVA / LLDPE / POE matrix with smaller particle size. This avoids stress concentration caused by large particle aggregation, reduces the probability of crack initiation under external force, and improves the overall tensile strength and impact resistance of the insulation layer. Furthermore, branched polyethyleneimine can interact with the polyolefin matrix and inorganic filler surface, improving interfacial bonding and thus enhancing the strength and structural stability of the insulation layer. At the same time, the uniformly dispersed modified zinc borate can fill the tiny voids in the matrix, making the overall structure of the insulation layer more compact without destroying the continuous phase structure of the polyolefin matrix itself. This improves strength while preserving the toughness of the matrix, avoiding the material embrittlement problem caused by large additions of ordinary zinc borate.

[0026] Branched polyethyleneimine itself contains nitrogen, which can form a boron-phosphorus-nitrogen ternary synergistic flame retardant system with the boron element in zinc borate and the phosphorus-nitrogen synergist in the formulation: During combustion, the nitrogen source can promote the foaming of the expanded char layer, the boron source can stabilize the char layer structure, and the phosphorus source can catalyze dehydration into char. The three work together to form a more fluffy, dense, and stable expanded barrier char layer than the ordinary binary system, which greatly improves the barrier effect. In addition, the uniformly dispersed zinc borate can form a glassy coating layer more quickly during combustion. Combined with the gas phase dilution effect of the nitrogen source, it can further reduce the release of smoke during combustion, while improving the strength of the char layer, inhibiting the shedding of molten droplets, and completely avoiding secondary fires caused by molten droplets. Compared with ordinary zinc borate, the smoke suppression and anti-dripping effects are more significantly improved.

[0027] Preferably, the insulating material further comprises 2-5 parts of bismaleimide-modified calcium sulfate whiskers and 2-5 parts of allyl polyoxyethylene ether-modified potassium titanate whiskers.

[0028] By adopting the above technical solutions, bismaleimide-modified calcium sulfate whiskers and allyl polyoxyethylene ether-modified potassium titanate whiskers give the insulating material high strength and high toughness. Bismaleimide and allyl polyoxyethylene ether can crosslink to form a connecting network, improving the compatibility of calcium sulfate whiskers and potassium titanate whiskers with the polyolefin substrate, increasing the structural density and crosslinking network stability, thereby improving the toughness of the insulating layer. Furthermore, bismaleimide has active double bonds that react with the polyolefin matrix, improving the interfacial bonding force between calcium sulfate whiskers and EVA, LLDPE, and POE. On the surface of potassium titanate whiskers, allyl polyoxyethylene ether can, on the one hand, prevent whisker agglomeration by utilizing steric hindrance, ensuring whisker dispersion, and on the other hand, allyl groups can participate in the crosslinking reaction, further improving the density and bonding force of the various substances inside the insulating layer, thereby improving the strength and toughness of the insulating layer.

[0029] When the insulation layer with a high cross-linked network and high structural density is subjected to external impact and cracks are generated, the whiskers will consume the fracture energy through three effects: whisker pull-out, crack bridging, and crack deflection. When the whiskers are pulled out of the matrix, the friction consumes energy; bridging the two sides of the crack prevents crack propagation; and forcing the crack to deflect increases the fracture path, ultimately improving the impact toughness of the insulation layer and solving the problem of embrittlement caused by adding a large amount of flame retardant filler.

[0030] The cross-linked network formed by bismaleimide-modified calcium sulfate whiskers and allyl polyoxyethylene ether-modified potassium titanate whiskers in the insulation layer can not only restrain the flow and migration of molten droplets during combustion, but also form an ordered fibrous skeleton in the char layer, ensuring the strength and thermal stability of the char layer and preventing char layer cracking from affecting flame retardancy. Furthermore, bismaleimide can promote char formation in the nearby matrix during combustion, while the whiskers are responsible for stabilizing the char skeleton and ensuring its agglomerated flame retardant effect. At the same time, potassium titanate whiskers can transfer heat to avoid local overheating, and the allyl groups in allyl polyoxyethylene ether can further improve the thermal stability of the insulation layer, slow down the combustion process, and improve the flame retardant effect of the insulation layer.

[0031] Secondly, this application provides a method for manufacturing a flexible B1-grade flame-retardant power cord, employing the following technical solution: A method for manufacturing a flexible B1-grade flame-retardant power cord includes the following steps: S1. Preparation of conductor (1); S2. Insulating material is extruded onto the surface of conductor (1), and the insulating material forms an insulating layer (2) to obtain the finished power cord.

[0032] By adopting the above technical solution, the power cord produced has the advantages of having a B1 flame retardant rating, a Shore A hardness of no more than 92HA, and compliance with both RoHS 2.0 and REACH environmental protection requirements.

[0033] In summary, this application has the following beneficial effects: 1. EVA, LLDPE, and POE are combined. EVA serves as the main elastic matrix, providing flexibility and flame retardancy synergy. POE's high elasticity and flexibility improve the low-temperature impact resistance and elongation of the power cord, thereby enhancing the flexibility of the insulation material. LLDPE can improve the tensile strength and abrasion resistance of the insulation layer, further ensuring the strength and flexibility of the insulation material, giving the power cord a Shore A hardness not exceeding 92HA. Halogen-free flame retardants and phosphorus-nitrogen synergists are combined to further improve the flame retardancy of the power cord. Combined with fillers, the strength and flame retardant effect are further improved, enabling the power layer to achieve a B1 flame retardancy rating. Furthermore, the halogen-free flame retardant is environmentally friendly, meeting both RoHS 2.0 and REACH environmental compliance requirements.

[0034] 2. The combination of bismaleimide, allyl polyoxyethylene ether, and branched polyethyleneimine forms a cross-linking network. Branched polyethyleneimine promotes the expansion of the char layer, while bismaleimide-modified calcium sulfate whiskers act as an inert skeleton, interspersed and supported within the expanded char layer, significantly improving its mechanical strength and thermal stability. This prevents the char layer from cracking and falling off due to heat. In addition to ensuring the stability of the char layer, the allyl polyoxyethylene ether-modified potassium titanate whiskers are uniformly dispersed in the char layer, further filling the pores and making the barrier layer denser. Ultimately, a three-layer composite barrier structure of glass phase, foamed char layer, and fiber skeleton is formed, which isolates oxygen and heat from being transferred to the internal matrix, significantly slowing down the combustion rate and improving the flame retardant effect. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of the power line in Embodiment 1 of this application; In the diagram: 1. Conductor; 2. Insulating layer. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0037] Example of preparation of zinc borate with loading Preparation Example 1: Zinc borate loaded with borate was prepared using the following method: 1 kg of zinc borate was placed in 10 kg of branched polyethyleneimine solution. The average particle size of zinc borate was 100 nm. The mass fraction of the branched polyethyleneimine solution was 3%, and the solvent was water. The solution was ultrasonically dispersed at 60 °C for 30 min and then stirred at 200 r / min for 2 h. Zinc borate was then separated, dried, and air-jet pulverized to obtain the finished product. The average particle size of the finished product was less than 200 nm.

[0038] Preparation example of bismaleimide modified calcium sulfate whiskers Preparation Example 2: Bismaleimide-modified calcium sulfate whiskers were prepared by the following method: 1 kg of calcium sulfate whiskers were added to 10 kg of bismaleimide solution. The average length of the calcium sulfate whiskers was 30 μm. The mass fraction of the bismaleimide solution was 2%. The solvent was N,N-dimethylformamide. The dissolution temperature of the bismaleimide solution was 60℃. After maintaining the temperature at 60℃ and ultrasonically dispersing for 30 min, the mixture was stirred at 200 r / min for 2 h. Then, the calcium sulfate whiskers were separated, dried, and dispersed to obtain the finished bismaleimide-modified calcium sulfate whiskers with an average particle size of less than 50 μm.

[0039] Preparation example of potassium titanate whiskers modified with allyl polyoxyethylene ether Preparation Example 3: Allyl polyoxyethylene ether modified potassium titanate whiskers were prepared by the following method: 1 kg of potassium titanate whiskers were added to 10 kg of allyl polyoxyethylene ether solution. The average length of the potassium titanate whiskers was 10 μm. The mass fraction of the allyl polyoxyethylene ether solution was 2%. The solvent was water. The mixture was kept at 60 °C and ultrasonically dispersed for 30 min. Then, it was stirred at 200 r / min for 2 h. The potassium titanate whiskers were then separated, dried, and dispersed to obtain the finished allyl polyoxyethylene ether modified potassium titanate whiskers with an average particle size of less than 20 μm. Example

[0040] Among the following raw materials, magnesium hydroxide was purchased from Dingxi Kaimete New Material Technology Co., Ltd., model GM3SA; aluminum hydroxide was purchased from Linyi Banlan Chemical Technology Co., Ltd., model H-WF-2N; and other raw materials were all commercially available.

[0041] Example 1: A flexible B1-grade flame-retardant power cord: The system includes conductor 1 and insulation layer 2. The insulation material of insulation layer 2 comprises: 50 kg EVA, 30 kg LLDPE, 20 kg POE, 140 kg halogen-free flame retardant, 20 kg phosphorus-nitrogen synergist, 9.5 kg interface modifier, 7 kg filler, 0.6 kg antioxidant, and 1.5 kg lubricant. The EVA contains 28% VA, the LLDPE is a C6 copolymer, the POE contains 25% octene, and the halogen-free flame retardant consists of 85 kg magnesium hydroxide and 55 kg aluminum hydroxide, wherein the magnesium hydroxide has a D... 50 It is 1.5 μm, aluminum hydroxide D 50 The particle size is 1.0 μm; the phosphorus-nitrogen synergist consists of 15 kg ammonium polyphosphate and 5 kg melamine cyanurate; the interface modifier consists of 8 kg maleic anhydride-grafted POE and 1.5 kg silane coupling agent KH-550, with a grafting rate of 0.8% for maleic anhydride-grafted POE; the filler consists of 3 kg nano silica and 4 kg zinc borate, with an average particle size of 15 nm for nano silica and type 2335 zinc borate; the antioxidant consists of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2; the lubricant consists of 1 kg calcium stearate and 0.5 kg polyethylene wax. The manufacturing method is as follows: S1. Select bare copper monofilaments with a diameter of 0.3mm, and twist 56 monofilaments together using the standard twisting method to form a cross-sectional area of ​​4mm². 2 Conductor 1 has an outer diameter of approximately 2.4 mm and a stranding pitch ratio controlled at 14-16 times; S2. Weigh the insulating material and dry it at 70℃ for 2 hours. Then, premix it in a high-speed mixer for 5 minutes, and then add it to a mixer. Mix it at 180℃ for 15 minutes, and then extrude it through a twin-screw extruder to obtain insulating granules. Add the insulating granules to a single-screw extruder and use an extrusion method to control the temperature of each zone of the extruder as follows: feeding section 130℃, second section 150℃, third section 160℃, die section 165℃, neck section 185℃, and head section 165℃. Extrude the insulating granules evenly onto the outside of a 4mm² conductor 1 to form an insulating layer 2. The nominal thickness of the insulating layer 2 is 0.8mm. After cooling and shaping in a water bath, the wire is wound up to obtain the finished power cord.

[0042] Example 2: The difference between this example and Example 1 is that: The system includes conductor 1 and insulation layer 2. The insulation material of insulation layer 2 comprises: 40 kg EVA, 20 kg LLDPE, 15 kg POE, 130 kg halogen-free flame retardant, 15 kg phosphorus-nitrogen synergist, 7 kg interface modifier, 4 kg filler, 0.5 kg antioxidant, and 0.8 kg lubricant. The halogen-free flame retardant consists of 80 kg magnesium hydroxide and 50 kg aluminum hydroxide, wherein the magnesium hydroxide has a D... 50 It is 1.5 μm, aluminum hydroxide D 50 The particle size is 1.0 μm; the phosphorus-nitrogen synergist consists of 12 kg ammonium polyphosphate and 3 kg melamine cyanurate; the interface modifier consists of 6 kg maleic anhydride-grafted POE and 1 kg silane coupling agent KH-550, with a grafting rate of 0.8% for maleic anhydride-grafted POE; the filler consists of 2 kg nano silica and 2 kg zinc borate, with an average particle size of 15 nm for nano silica and type 2335 zinc borate; the antioxidant consists of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2; the lubricant consists of 0.6 kg calcium stearate and 0.2 kg polyethylene wax. The manufacturing method is as follows: S1. Select bare copper monofilaments with a diameter of 0.3mm, and twist 84 monofilaments together using the standard twisting method to form a cross-sectional area of ​​6mm². 2 Conductor 1; S2. Weigh the insulating material and dry it at 70℃ for 2 hours. Then, premix it in a high-speed mixer for 5 minutes, then add it to a mixer and mix it at 175℃ for 20 minutes. Then, extrude and granulate it through a twin-screw extruder to obtain insulating granules. Add the insulating granules to a single-screw extruder and use an extrusion method to control the temperature of each zone of the extruder as follows: feeding section 130℃, second section 150℃, third section 160℃, die section 165℃, neck section 185℃, and head section 165℃. Extrude the insulating granules evenly onto the outside of a 6mm² conductor 1 to form an insulating layer 2. The nominal thickness of the insulating layer 2 is 0.8mm. After cooling and shaping in a water bath, the wire is wound up to obtain the finished power cord.

[0043] Example 3: The difference between this example and Example 1 is that: The system includes conductor 1 and insulation layer 2. The insulation material of insulation layer 2 comprises: 60 kg EVA, 40 kg LLDPE, 25 kg POE, 150 kg halogen-free flame retardant, 25 kg phosphorus-nitrogen synergist, 12 kg interface modifier, 11 kg filler, 0.8 kg antioxidant, and 2.2 kg lubricant. The halogen-free flame retardant consists of 90 kg magnesium hydroxide and 60 kg aluminum hydroxide, wherein the magnesium hydroxide has a D... 50 It is 1.5 μm, aluminum hydroxide D 50 The particle size is 1.0 μm; the phosphorus-nitrogen synergist consists of 18 kg ammonium polyphosphate and 7 kg melamine cyanurate; the interface modifier consists of 10 kg maleic anhydride-grafted POE and 2 kg silane coupling agent KH-550, with a grafting rate of 0.8% for maleic anhydride-grafted POE; the filler consists of 5 kg nano silica and 6 kg zinc borate, with an average particle size of 15 nm for nano silica and type 2335 zinc borate; the antioxidant consists of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2; the lubricant consists of 1.4 kg calcium stearate and 0.8 kg polyethylene wax. The manufacturing method is as follows: S1. Select bare copper monofilaments with a diameter of 0.4mm, and twist 119 monofilaments together using the standard twisting method to form a cross-sectional area of ​​16mm². 2 Conductor 1; S2. Weigh the insulating material and dry it at 70℃ for 2 hours. Then, premix it in a high-speed mixer for 5 minutes, and then add it to a mixer. Mix it at 185℃ for 15 minutes, and then extrude it through a twin-screw extruder to obtain insulating granules. Add the insulating granules to a single-screw extruder and use an extrusion method to control the temperature of each zone of the extruder as follows: feeding section 130℃, second section 150℃, third section 160℃, die section 165℃, neck section 185℃, and head section 165℃. Extrude the insulating granules evenly onto the outside of a 16mm² conductor 1 to form an insulating layer 2. The nominal thickness of the insulating layer 2 is 0.8mm. After cooling and shaping in a water bath, the wire is wound up to obtain the finished power cord.

[0044] Example 4: The difference between this example and Example 1 is that: The zinc borate used as the insulating material is the modified zinc borate prepared in Example 1.

[0045] Example 5: The difference between this example and Example 4 is that: 4 kg of bismaleimide-modified calcium sulfate whiskers and 4 kg of allyl polyoxyethylene ether-modified potassium titanate whiskers were added to the insulating material. The bismaleimide-modified calcium sulfate whiskers were those prepared in Preparation Example 2, and the allyl polyoxyethylene ether-modified potassium titanate whiskers were those prepared in Preparation Example 3.

[0046] Example 6: The difference between this example and Example 5 is that: Add 2 kg of bismaleimide-modified calcium sulfate whiskers and 2 kg of allyl polyoxyethylene ether-modified potassium titanate whiskers to the insulating material.

[0047] Example 7: The difference between this example and Example 5 is that: Add 5 kg of bismaleimide-modified calcium sulfate whiskers and 5 kg of allyl polyoxyethylene ether-modified potassium titanate whiskers to the insulating material.

[0048] Example 8: The difference between this example and Example 5 is that: In the insulating material, bismaleimide-modified calcium sulfate whiskers are replaced with an equal mass of calcium sulfate whiskers, and allyl polyoxyethylene ether-modified potassium titanate whiskers are replaced with an equal mass of potassium titanate whiskers.

[0049] Performance testing 1. Flame retardant performance testing The finished power cords were tested using the methods described in Examples 1-8, and the oxygen index of the insulation layer of the power cords was tested in accordance with GB / T2406.2-2009. The data were recorded.

[0050] 2. Mechanical performance testing The finished power cords were tested using the methods described in Examples 1-5 and 8, respectively. The Shore hardness of the insulation layer was tested according to GB / T2411-2018, and the tensile strength and elongation at break were tested according to GB / T5013. Data were recorded. Table 1 Performance Test Table (In the table below, " / " indicates that the corresponding embodiment did not test this item and there is no data)

[0051] 3. Environmental protection testing The finished power cords were tested using the method in Example 1. The content of substances in the insulation layer of the power cords was tested in accordance with GB / T39560. The contents of lead (8 ppm), cadmium (6 ppm), mercury (5 ppm), hexavalent chromium (32 ppm), PBB (28 ppm), and PBDE (31 ppm) all met the RoHS 2.0 limit requirements. The REACH SVHC substance screening results showed that no excessive items were detected.

[0052] As can be seen from Examples 1-3 and Table 1, the power cord prepared in this application has the advantages of good flame retardancy, Shore hardness below 92HA and environmental friendliness. At the same time, it has good tensile strength and elongation at break, indicating high strength and good toughness, which can improve the quality of the power cord.

[0053] As can be seen from Examples 1 and 4 and Table 1, loading branched polyethyleneimine onto the surface of zinc borate not only improves the compatibility and bonding effect between modified zinc borate and the polyolefin matrix, and enhances the interfacial bonding force, thereby increasing the tensile strength, but also the branched polyethyleneimine itself contains nitrogen, which can form a boron-phosphorus-nitrogen ternary synergistic flame retardant system with the boron element of zinc borate and the phosphorus-nitrogen synergist in the formulation, thereby improving the flame retardant effect.

[0054] As can be seen from Examples 4 and 5-7 and Table 1, the addition of bismaleimide-modified calcium sulfate whiskers and allyl polyoxyethylene ether-modified potassium titanate whiskers can further improve the flame retardancy of the power cord. Although the Shore hardness is increased, it is lower than 92HA, which meets the requirements. At the same time, the tensile strength is high and the elongation at break is appropriate, ensuring that the finished power cord has high mechanical strength and good flexibility and flame retardancy.

[0055] As can be seen from Examples 5 and 8 and Table 1, bismaleimide, allyl polyoxyethylene ether, and branched polyethyleneimine can be cross-linked to form a connecting network. Branched polyethyleneimine can promote the expansion of the carbon layer and ensure the stability of the carbon layer. The cross-linked network can further improve the mechanical strength and toughness.

[0056] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A flexible B1-grade flame-retardant power cord, characterized in that, It includes a conductor (1) and an insulating layer (2); the insulating layer (2) is made of insulating material, which includes the following raw materials in parts by weight: 40-60 parts of EVA, 20-40 parts of LLDPE, 15-25 parts of POE, 130-150 parts of halogen-free flame retardant, 15-25 parts of phosphorus-nitrogen synergist, 7-12 parts of interface modifier, 4-11 parts of filler, 0.5-0.8 parts of antioxidant, and 0.8-2.2 parts of lubricant.

2. The flexible B1-grade flame-retardant power cord according to claim 1, characterized in that: The halogen-free flame retardant comprises 80-90 parts of magnesium hydroxide and 50-60 parts of aluminum hydroxide. The magnesium hydroxide is surface-treated with stearic acid, and the aluminum hydroxide is surface-treated with aluminate.

3. A flexible B1-grade flame-retardant power cord according to claim 1, characterized in that, The phosphorus-nitrogen synergist comprises 12-18 parts of ammonium polyphosphate and 3-7 parts of melamine cyanurate.

4. A flexible B1-grade flame-retardant power cord according to claim 1, characterized in that, The interface modifier comprises 6-10 parts maleic anhydride-grafted POE and 1-2 parts silane coupling agent KH-550.

5. A flexible B1-grade flame-retardant power cord according to claim 1, characterized in that, The lubricant comprises 0.6-1.4 parts calcium stearate and 0.2-0.8 parts polyethylene wax.

6. A flexible B1-grade flame-retardant power cord according to claim 1, characterized in that, The conductor is made of 56-119 bare copper monofilaments twisted together, with a diameter of 0.3-0.4 mm for the copper monofilaments and an interface agent of 4-16 mm. 2 .

7. A flexible B1-grade flame-retardant power cord according to claim 1, characterized in that, The filler comprises 2-5 parts nano-silica and 2-6 parts zinc borate.

8. A flexible B1-grade flame-retardant power cord according to claim 7, characterized in that, The zinc borate is a loaded zinc borate, which is prepared by treating zinc borate particles with a branched polyethyleneimine solution.

9. A flexible B1-grade flame-retardant power cord according to claim 1, characterized in that, The insulating material also includes 2-5 parts of bismaleimide-modified calcium sulfate whiskers and 2-5 parts of allyl polyoxyethylene ether-modified potassium titanate whiskers.

10. A method for manufacturing a flexible B1-grade flame-retardant power cord according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Preparation of conductor (1); S2. Insulating material is extruded onto the surface of conductor (1), and the insulating material forms an insulating layer (2) to obtain the finished power cord.

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