Low-smoke halogen-free flame-retardant environment-friendly power cable

Abstract

The invention relates to the technical field of cables, and provides a low-smoke halogen-free flame-retardant environment-friendly power cable which sequentially comprises a conductor, an insulating layer, a shielding layer and an outer sheath layer from inside to outside. The outer sheath layer is prepared from the following raw materials in parts by weight: 90-100 parts of high-density polyethylene, 40-50 parts of a flame retardant, 10-15 parts of an ethylene-butyl acrylate copolymer, 0.5-2 parts of an antioxidant, 1-3 parts of a plasticizer, 0.5-1.5 parts of a lubricant and 1.5-3 parts of a compatilizer; the flame retardant comprises the following raw materials in parts by weight: 100 parts of magnesium hydroxide, 18-20 parts of methyl methacrylate and 4-6 parts of itaconic acid. According to the technical scheme, the problem of poor flame retardance of the power cable in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable. Background Technology

[0002] As the core carrier of power transmission and distribution, power cables are widely used in many fields such as industrial production, urban infrastructure, and high-rise buildings. Their operational safety and environmental protection are of paramount importance. With the acceleration of urbanization and the advancement of smart grid construction, the market's requirements for cables in terms of fire prevention and environmental protection are becoming increasingly stringent. Traditional power cables mostly use halogenated polymer materials such as polyvinyl chloride, which easily produce a large amount of toxic and harmful gases, dense black smoke, and corrosive acid liquid when burned, polluting the environment. They have been gradually replaced by low-smoke halogen-free flame-retardant cables.

[0003] However, existing low-smoke halogen-free cables have poor flame retardancy. To improve this, a large amount of inorganic flame retardants such as magnesium hydroxide is usually added to the outer sheath. However, directly adding magnesium hydroxide to the cable's outer sheath material can lead to agglomeration, which prevents it from achieving its full flame-retardant effect. Therefore, there is a need to propose a low-smoke halogen-free flame-retardant environmentally friendly power cable. Summary of the Invention

[0004] This invention proposes a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable, which solves the problem of poor flame retardancy in power cables in related technologies.

[0005] The technical solution of the present invention is as follows: This invention proposes a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable, which comprises, from the inside out, a conductor, an insulation layer, a shielding layer, and an outer sheath layer. The outer sheath layer comprises the following raw materials in parts by weight: 90-100 parts of high-density polyethylene, 40-50 parts of flame retardant, 10-15 parts of ethylene-butyl acrylate copolymer, 0.5-2 parts of antioxidant, 1-3 parts of plasticizer, 0.5-1.5 parts of lubricant, and 1.5-3 parts of compatibilizer. The flame retardant comprises the following raw materials in parts by weight: 100 parts magnesium hydroxide, 18-20 parts methyl methacrylate, and 4-6 parts itaconic acid.

[0006] As a further technical solution, the mass ratio of methyl methacrylate to itaconic acid is 3~5:1, preferably 4:1.

[0007] As a further technical solution, the preparation method of the flame retardant includes the following steps: S1. Disperse magnesium hydroxide and silane coupling agent in water to obtain magnesium hydroxide aqueous dispersion; S2. Disperse sodium dodecylbenzenesulfonate in water, add methyl methacrylate and itaconic acid, emulsify at 60~65℃ for 20~30 min, cool, and then add an initiator to obtain an emulsion; S3. After mixing the emulsion and the magnesium hydroxide aqueous dispersion, the mixture is filtered and dried to obtain the flame retardant.

[0008] As a further technical solution, in step S1, the mass of the silane coupling agent is 3% to 5% of the mass of magnesium hydroxide.

[0009] As a further technical solution, the silane coupling agent is silane coupling agent KH-570.

[0010] As a further technical solution, in step S1, the mass-to-volume ratio of magnesium hydroxide and water is 1g:8mL.

[0011] As a further technical solution, in step S2, the mass-to-volume ratio of sodium dodecylbenzenesulfonate and water is 1g:50mL; the mass ratio of methyl methacrylate, sodium dodecylbenzenesulfonate and initiator is 100:6:2.

[0012] As a further technical solution, in step S2, the cooling is to cool to 35~40℃.

[0013] As a further technical solution, the initiator is ammonium persulfate.

[0014] As a further technical solution, in step S3, the mixing temperature is 65~75℃ and the time is 2.5~3h.

[0015] As a further technical solution, the ethylene-butyl acrylate copolymer includes a first ethylene-butyl acrylate copolymer and a second ethylene-butyl acrylate copolymer; the melt flow rates of the first ethylene-butyl acrylate copolymer and the second ethylene-butyl acrylate copolymer are different.

[0016] As a further technical solution, the melt flow rate of the first ethylene-butyl acrylate copolymer is 7.0 g / 10 min, and the test conditions are 190℃ / 2.16 kg; the melt flow rate of the second ethylene-butyl acrylate copolymer is 12 g / 10 min, and the test conditions are 190℃ / 2.16 kg.

[0017] This invention relates to a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable. By adding two components—a blend of ethylene-butyl acrylate copolymers with different melt flow rates—to the outer sheath layer, the impact toughness of the outer sheath layer can be improved. The first ethylene-butyl acrylate copolymer, with a lower melt flow rate, has a higher molecular weight and longer molecular chains, resulting in tighter entanglement with the high-density polyethylene matrix and higher interfacial bonding strength. The second ethylene-butyl acrylate copolymer, with a higher melt flow rate, has better fluidity and can form a more uniform dispersed phase within the high-density polyethylene matrix. The synergistic effect of these two components enhances the impact toughness of the outer sheath layer of the low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable.

[0018] As a further technical solution, the mass ratio of the first ethylene-butyl acrylate copolymer to the second ethylene-butyl acrylate copolymer is 6~8:3, preferably 7:3.

[0019] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 1098 and antioxidant 168.

[0020] As a further technical solution, the plasticizer includes one or both of dioctyl sebacate and trioctyl trimellitate.

[0021] As a further technical solution, the lubricant includes one or both of ethylene bis-stearamide and zinc stearate.

[0022] As a further technical solution, the compatibilizer is maleic anhydride-grafted polyethylene.

[0023] As a further technical solution, the conductor is made of 5 to 7 copper wires with a diameter of 5 to 10 mm twisted together.

[0024] As a further technical solution, the insulation layer is a cross-linked polyethylene insulation layer.

[0025] As a further technical solution, the shielding layer is a tin-plated copper wire braided shielding layer.

[0026] This invention also proposes a method for preparing a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable, comprising the following steps: A1. An insulating layer is formed by extruding insulating material onto the outside of the conductor; A2. The shielding material is woven into the outside of the insulation layer to form a shielding layer; A3. After mixing the raw materials for the outer sheath layer, they are extruded onto the outside of the shielding layer to obtain a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable.

[0027] The working principle and beneficial effects of this invention are as follows: This invention relates to a low-smoke halogen-free flame-retardant environmentally friendly power cable. By adding a flame retardant composed of magnesium hydroxide, methyl methacrylate, and itaconic acid to the outer sheath layer, the flame-retardant performance of the cable is improved. Firstly, magnesium hydroxide, the core inorganic flame-retardant component, undergoes an endothermic decomposition reaction upon heating, forming a dense inorganic barrier layer on the material surface that isolates oxygen and combustible gases, thus exerting a flame-retardant effect. Secondly, the polymer matrix formed by the polymerization of methyl methacrylate and itaconic acid can act as an organic coating layer, encapsulating the magnesium hydroxide particles and improving their dispersibility. This addresses the issue of magnesium hydroxide's tendency to agglomerate in the cable's outer sheath, further enhancing the flame-retardant effect and ultimately improving the flame-retardant performance of the low-smoke halogen-free flame-retardant environmentally friendly power cable. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] In the following examples and comparative examples, the high-density polyethylene (HDPE) was grade HHM5502LW; the first ethylene-butyl acrylate copolymer had a melt flow rate of 7.0 g / 10 min and was tested at 190°C / 2.16 kg, grade 3717AC; the second ethylene-butyl acrylate copolymer had a melt flow rate of 12 g / 10 min and was tested at 190°C / 2.16 kg, grade HP4051; maleic anhydride-grafted polyethylene (MEP) was model E60P; cross-linked polyethylene (COP) was grade XHF1500X04 and was purchased from LyondellBasell Polyolefins (Shanghai) Co., Ltd.; and magnesium hydroxide had an average particle size of 7 μm.

[0030] Example 1 A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable comprises, from the inside out, a conductor, a shielding layer, an insulation layer, and an outer sheath layer. The outer sheath layer comprises the following raw materials in parts by weight: 90 parts high-density polyethylene, 40 parts flame retardant, 10 parts ethylene-butyl acrylate copolymer, 0.5 parts antioxidant 1010, 1 part dioctyl sebacate, 0.5 parts ethylene bis-stearamide, and 1.5 parts maleic anhydride-grafted polyethylene; the ethylene-butyl acrylate copolymer is a first type of ethylene-butyl acrylate copolymer. The preparation method of flame retardant includes the following steps: S1. Disperse 100 parts of magnesium hydroxide and silane coupling agent KH-570 in water to obtain a magnesium hydroxide aqueous dispersion; the mass-to-volume ratio of magnesium hydroxide to water is 1 g: 8 mL; the mass of silane coupling agent KH-570 is 3% of the mass of magnesium hydroxide; S2. Disperse sodium dodecylbenzenesulfonate in water, add 18 parts methyl methacrylate and 6 parts itaconic acid, emulsify at 60°C for 30 min, cool to 40°C, and then add ammonium persulfate to obtain an emulsion; the mass-volume ratio of sodium dodecylbenzenesulfonate to water is 1 g: 50 mL; the mass ratio of methyl methacrylate, sodium dodecylbenzenesulfonate and initiator is 100:6:2; S3. After mixing the emulsion and magnesium hydroxide aqueous dispersion at 65°C for 3 hours, the mixture is filtered and dried to obtain the flame retardant. A method for preparing a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable includes the following steps: A1. After stranding six copper wires with a diameter of 8mm into a conductor, cross-linked polyethylene is extruded onto the outside of the conductor to form an insulation layer. A2. Tinned copper wire is braided onto the outside of the insulation layer to form a tinned copper wire braided shielding layer; A3. After mixing the raw materials for the outer sheath layer, they are extruded onto the outside of the shielding layer to obtain a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable.

[0031] Example 2 A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable comprises, from the inside out, a conductor, a shielding layer, an insulation layer, and an outer sheath layer. The outer sheath layer comprises the following raw materials in parts by weight: 95 parts high-density polyethylene, 45 parts flame retardant, 12 parts ethylene-butyl acrylate copolymer, 1.5 parts antioxidant 1098, 2 parts trioctyl trimellitate, 1 part ethylene bis-stearamide, and 2 parts maleic anhydride-grafted polyethylene; the ethylene-butyl acrylate copolymer is a first type of ethylene-butyl acrylate copolymer. The preparation method of the flame retardant includes the following steps: S1. Disperse 100 parts of magnesium hydroxide and silane coupling agent KH-570 in water to obtain a magnesium hydroxide aqueous dispersion; the mass-to-volume ratio of magnesium hydroxide to water is 1 g: 8 mL; the mass of silane coupling agent KH-570 is 4% of the mass of magnesium hydroxide; S2. Disperse sodium dodecylbenzenesulfonate in water, add 18 parts methyl methacrylate and 6 parts itaconic acid, emulsify at 63°C for 25 min, cool to 40°C, and then add ammonium persulfate to obtain an emulsion; the mass-volume ratio of sodium dodecylbenzenesulfonate to water is 1 g: 50 mL; the mass ratio of methyl methacrylate, sodium dodecylbenzenesulfonate and initiator is 100:6:2; S3. After mixing the emulsion and magnesium hydroxide aqueous dispersion at 70°C for 2.5 hours, the mixture is filtered and dried to obtain the flame retardant. A method for preparing a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable is the same as in Example 1.

[0032] Example 3 A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable comprises, from the inside out, a conductor, a shielding layer, an insulation layer, and an outer sheath layer. The outer sheath layer comprises the following raw materials in parts by weight: 100 parts high-density polyethylene, 50 parts flame retardant, 15 parts ethylene-butyl acrylate copolymer, 2 parts antioxidant 168, 3 parts trioctyl trimellitate, 1.5 parts zinc stearate, and 3 parts maleic anhydride-grafted polyethylene; the ethylene-butyl acrylate copolymer is a first type of ethylene-butyl acrylate copolymer. The preparation method of the flame retardant includes the following steps: S1. Disperse 100 parts of magnesium hydroxide and silane coupling agent KH-570 in water to obtain a magnesium hydroxide aqueous dispersion; the mass-to-volume ratio of magnesium hydroxide to water is 1g:8mL; the mass of silane coupling agent KH-570 is 5% of the mass of magnesium hydroxide; S2. Disperse sodium dodecylbenzenesulfonate in water, add 18 parts methyl methacrylate and 6 parts itaconic acid, emulsify at 65°C for 20 min, cool to 40°C, and then add ammonium persulfate to obtain an emulsion; the mass-volume ratio of sodium dodecylbenzenesulfonate to water is 1 g: 50 mL; the mass ratio of methyl methacrylate, sodium dodecylbenzenesulfonate and initiator is 100:6:2; S3. After mixing the emulsion and magnesium hydroxide aqueous dispersion at 75°C for 2.5 hours, the mixture is filtered and dried to obtain the flame retardant. A method for preparing a low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable is the same as in Example 1.

[0033] Example 4 Compared with Example 1, the only difference in this example is that in the preparation method of the flame retardant in this example, methyl methacrylate is 19.2 parts and itaconic acid is 4.8 parts.

[0034] Example 5 Compared with Example 1, the only difference in this example is that in the preparation method of the flame retardant in this example, methyl methacrylate is 20 parts and itaconic acid is 4 parts.

[0035] Example 6 Compared with Example 1, the only difference in this example is that the ethylene-butyl acrylate copolymer in this example is composed of a first ethylene-butyl acrylate copolymer and a second ethylene-butyl acrylate copolymer with a mass ratio of 6:3.

[0036] Example 7 Compared with Example 1, the only difference in this example is that the ethylene-butyl acrylate copolymer in this example is composed of a first ethylene-butyl acrylate copolymer and a second ethylene-butyl acrylate copolymer with a mass ratio of 7:3.

[0037] Example 8 Compared with Example 1, the only difference in this example is that the ethylene-butyl acrylate copolymer in this example is composed of a first ethylene-butyl acrylate copolymer and a second ethylene-butyl acrylate copolymer with a mass ratio of 8:3.

[0038] Example 9 Compared with Example 1, the only difference in this example is that the ethylene-butyl acrylate copolymer in this example is a second ethylene-butyl acrylate copolymer.

[0039] Comparative Example 1 Compared with Example 1, the only difference in this comparative example is that in the preparation method of the flame retardant in this comparative example, itaconic acid is replaced with an equal amount of methyl methacrylate.

[0040] Comparative Example 2 Compared with Example 1, the only difference in this comparative example is that in the preparation method of the flame retardant in this comparative example, methyl methacrylate is replaced with an equal amount of itaconic acid.

[0041] Comparative Example 3 The only difference between this comparative example and Example 1 is that the flame retardant used in this comparative example is magnesium hydroxide.

[0042] The outer sheaths of the low-smoke halogen-free flame-retardant environmentally friendly power cables prepared in Examples 1-9 and Comparative Examples 1-3 were tested according to the following methods: 1. Flame retardant performance test: The oxygen index of the outer sheath of the medium voltage fireproof cable was determined according to the test method specified in GB / T 2406.2-2009 "Determination of burning behavior by oxygen index method for plastics - Part 2: Room temperature test"; the sample type was type V, and the ignition method was method B, diffusion ignition method; 2. Impact toughness test: According to the GB / T 1843 / A method specified in Table 1 of GB / T 1843-2008 "Determination of impact strength of plastic cantilever beam", the notched impact strength is tested using a cantilever beam impact testing machine. The sample size is 80mm×10mm×4mm, and the notch type is A. The test results are shown in Tables 1 and 2: Table 1. Test results of flame retardant performance of the outer sheath of low-smoke halogen-free flame-retardant environmentally friendly power cables

[0043] According to the data in Table 1, when the flame retardant is composed of magnesium hydroxide, methyl methacrylate and itaconic acid, it can improve the flame retardant performance of the outer sheath of low-smoke halogen-free flame-retardant environmentally friendly power cables.

[0044] Table 2. Impact toughness test results of the outer sheath of low-smoke halogen-free flame-retardant environmentally friendly power cables

[0045] According to the data in Table 2, the present invention can improve the impact strength of the outer sheath of low-smoke halogen-free flame-retardant environmentally friendly power cables by using a combination of a first ethylene-butyl acrylate copolymer and a second ethylene-butyl acrylate copolymer with different melt flow rates, thus giving the outer sheath of the low-smoke halogen-free flame-retardant environmentally friendly power cables good impact toughness.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable, characterized in that: From the inside out, it includes a conductor, an insulating layer, a shielding layer, and an outer sheath layer. The outer sheath layer comprises the following raw materials in parts by weight: 90-100 parts high-density polyethylene, 40-50 parts flame retardant, 10-15 parts ethylene-butyl acrylate copolymer, 0.5-2 parts antioxidant, 1-3 parts plasticizer, 0.5-1.5 parts lubricant, and 1.5-3 parts compatibilizer. The flame retardant comprises the following raw materials in parts by weight: 100 parts magnesium hydroxide, 18-20 parts methyl methacrylate, and 4-6 parts itaconic acid.

2. The low-smoke halogen-free flame-retardant environmentally friendly power cable according to claim 1, characterized in that, The mass ratio of methyl methacrylate to itaconic acid is 3~5:

1.

3. The low-smoke halogen-free flame-retardant environmentally friendly power cable according to claim 1, characterized in that, The method for preparing the flame retardant includes the following steps: S1. Disperse magnesium hydroxide and silane coupling agent in water to obtain magnesium hydroxide aqueous dispersion; S2. Disperse sodium dodecylbenzenesulfonate in water, add methyl methacrylate and itaconic acid for emulsification, and then add an initiator to obtain an emulsion; S3. After mixing the emulsion and the magnesium hydroxide aqueous dispersion, the mixture is filtered and dried to obtain the flame retardant.

4. The low-smoke halogen-free flame-retardant environmentally friendly power cable according to claim 3, characterized in that, In step S1, the mass of the silane coupling agent is 3% to 5% of the mass of magnesium hydroxide.

5. The low-smoke halogen-free flame-retardant environmentally friendly power cable according to claim 3, characterized in that, In step S3, the mixing temperature is 65~75℃ and the time is 2.5~3h.

6. The low-smoke halogen-free flame-retardant environmentally friendly power cable according to claim 1, characterized in that, The ethylene-butyl acrylate copolymer includes a first ethylene-butyl acrylate copolymer and a second ethylene-butyl acrylate copolymer; the first ethylene-butyl acrylate copolymer and the second ethylene-butyl acrylate copolymer have different melt flow rates.

7. A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable according to claim 6, characterized in that, The melt flow rate of the first ethylene-butyl acrylate copolymer was 7.0 g / 10 min, and the test conditions were 190℃ / 2.16 kg; the melt flow rate of the second ethylene-butyl acrylate copolymer was 12 g / 10 min, and the test conditions were 190℃ / 2.16 kg.

8. A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable according to claim 7, characterized in that, The mass ratio of the first ethylene-butyl acrylate copolymer to the second ethylene-butyl acrylate copolymer is 6~8:

3.

9. A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable according to claim 1, characterized in that, The antioxidants include one or more of antioxidants 1010, 1098, and 168.

10. A low-smoke, halogen-free, flame-retardant, and environmentally friendly power cable according to claim 1, characterized in that, The plasticizer includes one or both of dioctyl sebacate and trioctyl trimellitate.

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