Low-smoke halogen-free flame-retardant polyolefin sheath environmental protection cable and preparation method thereof

Abstract

This invention discloses a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable and its preparation method, belonging to the technical field of wire and cable materials. The cable includes a low-smoke, halogen-free, flame-retardant polyolefin sheath and a cable body. The low-smoke, halogen-free, flame-retardant polyolefin sheath is made of polyolefin sheath material, which is prepared through the following steps: setting the temperature to 180-200℃, mixing polyolefin resin and antioxidant, adding vinyl epoxy silicone resin and mixing, adding phosphorus-containing polyamide and continuing mixing, cooling to 105-110℃, adding a crosslinking agent and mixing to obtain the polyolefin sheath material. Through the molecular-level synergistic flame-retardant effect of vinyl epoxy silicone resin and phosphorus-containing polyamide, no additional flame retardant is needed, avoiding the addition of toxic flame retardants such as halogens, and no release of toxic hydrogen halide gas. The synergistic flame retardancy of vinyl epoxy silicone resin and phosphorus-containing polyamide solves the problem of poor flame-retardant performance of polyolefin sheaths.

Description

Technical Field

[0001] This invention belongs to the field of wire and cable materials technology, specifically relating to a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable and its preparation method. Background Technology

[0002] In the wire and cable industry, the selection of flame-retardant wire and cable sheathing materials is crucial. Currently, most flame-retardant wire and cable sheathing materials are polyvinyl chloride (PVC) and polyolefin polymers with added halogenated flame retardants. PVC and traditional halogenated flame retardants release large amounts of toxic gases during combustion, causing significant environmental impact. In fires, they release large amounts of toxic and corrosive gases and smoke, severely affecting personnel escape and fire rescue operations. Therefore, their use is subject to many restrictions.

[0003] To overcome the aforementioned problems, polyolefin polymers and halogen-free flame retardants are often used as alternative materials. Commonly used flame retardants include metal hydroxides (such as aluminum hydroxide and magnesium hydroxide), phosphorus-based flame retardants (such as red phosphorus and phosphate esters), silicone-based flame retardants (such as silicone rubber and silicone resin), and intumescent flame retardants. These flame retardants function through mechanisms such as gas-phase flame retardancy, condensed-phase flame retardancy, or synergistic flame retardancy, but they still face many challenges in practical applications. First, polyolefins, as non-polar saturated carbon chain polymers, have poor compatibility with most flame retardants, leading to easy phase separation during blending, affecting the mechanical properties and flame retardant efficiency of the material, and posing safety hazards in practical applications. Second, achieving ideal flame retardant effects often requires adding a high proportion of flame retardant (usually 30% to 60%), which significantly reduces the mechanical properties and processing fluidity of the material. In addition, some flame retardants (such as metal hydroxides) are prone to decomposition and failure during high-temperature processing, while phosphorus-based flame retardants have migration and precipitation problems. Summary of the Invention

[0004] The purpose of this invention is to provide a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable and its preparation method, so as to solve the problem of poor flame-retardant performance of the polyolefin sheath of the cable.

[0005] The objective of this invention can be achieved through the following technical solutions: A low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable includes a low-smoke, halogen-free, flame-retardant polyolefin sheath and a cable body. The low-smoke, halogen-free, flame-retardant polyolefin sheath is made of polyolefin sheath material, which is prepared by the following steps: setting the temperature to 180-200℃, adding polyolefin resin and antioxidant and mixing for 2-3 minutes, adding vinyl epoxy silicone resin and mixing for 3-5 minutes, adding phosphorus-containing polyamide and continuing to mix for 3-5 minutes, cooling to 105-110℃, adding crosslinking agent and mixing for 2-3 minutes to obtain the polyolefin sheath material.

[0006] Further, by weight, the product contains 80 parts of polyolefin resin, 0.3-0.4 parts of antioxidant, 2-4 parts of vinyl epoxy silicone resin, 16-18 parts of phosphorus-containing polyamide, and 1.3-1.5 parts of crosslinking agent.

[0007] Furthermore, the polyolefin resin is low-density polyethylene; the crosslinking agent is dicumyl peroxide.

[0008] Furthermore, the phosphorus-containing polyamide is prepared by the following steps: Triamine methylphosphine oxide and a dicarboxylic acid were added to N-methylpyrrolidone, pyridine and triphenyl phosphite. Under nitrogen protection, the temperature was raised to 100°C and the mixture was stirred for 4-5 hours. After the reaction was completed, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain phosphorus-containing polyamide.

[0009] Furthermore, the dicarboxylic acid is one of adipic acid, sebacic acid, and dodecanoic acid; the molar ratio of triaminemethylphosphine oxide to the dicarboxylic acid is 1:1; the ratio of the amount of dicarboxylic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite is 10 mmol: 20 mL: 4 mL: 4 mL.

[0010] Furthermore, the vinyl epoxy silicone resin is prepared by hydrolysis and condensation of epoxy silane, alkoxy silane and vinyl silane.

[0011] Furthermore, the vinyl epoxy silicone resin is prepared by the following steps: Epoxysilane and alkoxysilane are added to an aqueous ethanol solution, heated to 70-75℃, stirred for 10-15 min, an organotin catalyst is added, and the reaction is stirred for 4-5 h. Vinylsilane is added and the reaction is continued for 3-4 h. After the reaction is completed, small molecule byproducts are removed by rotary evaporation to obtain vinyl epoxy silicone resin.

[0012] Furthermore, the molar ratio of epoxysilane, alkoxysilane, and vinylsilane is 0.4-0.5:3:0.1-0.3; The amount of organotin catalyst added is 1% to 2% of the total amount of silane.

[0013] Furthermore, the epoxy silane is one of 3-glycidyl etheroxypropylmethyldiethoxysilane and 3-glycidyl etheroxypropylmethyldimethoxysilane; The alkoxysilane is one of dimethyldimethoxysilane and diethoxydimethylsilane; The vinylsilane is one of dimethylethoxyvinylsilane and trivinylethoxysilane.

[0014] A method for preparing a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable includes the following steps: melting and extruding polyolefin sheath material at a temperature of 180-200℃, uniformly extruding it onto the surface of the cable body, and cooling it to obtain a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable.

[0015] The beneficial effects of this invention are: This invention provides a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable. The cable includes a low-smoke, halogen-free, flame-retardant polyolefin sheath made of polyolefin sheath material. In the preparation of the polyolefin sheath material, polyolefin resin, vinyl epoxy silicone resin, and phosphorus-containing polyamide are used as the main materials. Through molecular-level synergistic flame retardancy, no additional flame retardants are needed, avoiding the addition of toxic flame retardants such as halogens and preventing the release of toxic hydrogen halide gases. Furthermore, through the synergistic flame retardancy of vinyl epoxy silicone resin and phosphorus-containing polyamide, its oxygen index can be increased to over 30.5%, significantly superior to conventional polyolefin materials, thus solving the problem of poor flame retardant performance of polyolefin sheaths. Detailed Implementation

[0016] 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.

[0017] The following is a detailed description of a low-halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable and its preparation method, according to an embodiment of this application.

[0018] The first aspect of this application provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body. The low-smoke halogen-free flame-retardant polyolefin sheath is made of polyolefin sheath material, which is prepared by the following steps: Set the temperature to 180-200℃, add polyolefin resin and antioxidant and mix for 2-3 minutes, add vinyl epoxy silicone resin and mix for 3-5 minutes, add phosphorus-containing polyamide and continue mixing for 3-5 minutes, cool down to 105-110℃, add crosslinking agent and mix for 2-3 minutes to obtain polyolefin sheath material.

[0019] In some specific embodiments, by weight, there are 80 parts of polyolefin resin, 0.3-0.4 parts of antioxidant 1010, 24 parts of vinyl epoxy silicone resin, 16-18 parts of phosphorus-containing polyamide, and 1.3-1.5 parts of crosslinking agent.

[0020] In some specific embodiments, the polyolefin resin is low-density polyethylene, the antioxidant is antioxidant 1010, and the crosslinking agent is dicumyl peroxide.

[0021] In some specific embodiments, the phosphorus-containing polyamide is prepared by the following steps: Triamine methylphosphine oxide and a dicarboxylic acid were added to N-methylpyrrolidone, pyridine and triphenyl phosphite. Under nitrogen protection, the temperature was raised to 100°C and the mixture was stirred for 4-5 hours. After the reaction was completed, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain phosphorus-containing polyamide.

[0022] In some specific embodiments, the dicarboxylic acid is one of adipic acid, sebacic acid, and dodecanoic acid; the molar ratio of triaminemethylphosphine oxide to the dicarboxylic acid is 1:1; and the ratio of the amount of dicarboxylic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite is 10 mmol: 20 mL: 4 mL: 4 mL.

[0023] The synthesis of triaminemethylphosphine oxide was based on an existing method (Shao Yuena. Research on phosphorus-containing reactive monomers and high-performance polymers [D]. Hubei University for Nationalities, 2022. DOI:10.27764 / d.cnki.ghbmz.2022.000207.). Tetramethylolphosphine sulfate and methyl carbamate were mixed in a molar ratio of 1:8 and reacted at 107℃ for 2 hours. After the reaction, water was added for dilution, followed by the addition of 25% ammonia solution and stirring for another 6 hours. After vacuum drying at room temperature, 30% hydrogen peroxide solution was added for oxidation. The oxidized product was mixed with calcium hydroxide and water, heated under reflux for 5 hours, and then purged with carbon dioxide until neutral. After cooling, the mixture was filtered, and the filtrate was concentrated by rotary evaporation. Ethanol was added and filtered again. The ethanol was removed by rotary evaporation to obtain triaminemethylphosphine oxide. The molar ratio of tetramethylolphosphine sulfate, ammonia solution, hydrogen peroxide solution, and calcium hydroxide was 10g:20mL:15mL:5g.

[0024] In some specific embodiments, the vinyl epoxy silicone resin is prepared by hydrolysis and condensation of epoxy silane, alkoxy silane and vinyl silane.

[0025] In some specific embodiments, the vinyl epoxy silicone resin is prepared by the following steps: Epoxysilane and alkoxysilane are added to an aqueous ethanol solution, heated to 70-75℃, stirred for 10-15 min, an organotin catalyst is added, and the reaction is stirred for 4-5 h. Vinylsilane is added and the reaction is continued for 3-4 h. After the reaction is completed, small molecule byproducts are removed by rotary evaporation to obtain vinyl epoxy silicone resin.

[0026] In some specific embodiments, the molar ratio of epoxysilane, alkoxysilane and vinylsilane is 0.4-0.5:3:0.1-0.3; the amount of organotin catalyst added is 1% to 2% of the total amount of silane.

[0027] In some specific embodiments, the epoxy silane is one of 3-glycidyl etheroxypropylmethyldiethoxysilane and 3-glycidyl etheroxypropylmethyldimethoxysilane; The alkoxysilane is one of dimethyldimethoxysilane and diethoxydimethylsilane; The vinylsilane is one of dimethylethoxyvinylsilane and trivinylethoxysilane.

[0028] The second aspect of this application provides a method for preparing a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable, comprising the following steps: melting and extruding polyolefin sheath material at a temperature of 180-200°C, uniformly extruding it onto the surface of the cable body, and cooling it to obtain a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable.

[0029] In some specific embodiments, the cable body includes a conductor and an insulation layer, wherein the insulation layer is formed by wrapping the conductor with insulating material using an extruder, and the conductor is copper or aluminum.

[0030] The following is a detailed description with reference to specific examples.

[0031] Example 1 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 2 parts vinyl epoxy silicone resin, 18 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0032] The phosphorus-containing polyamide is prepared through the following steps: Triaminemethylphosphine oxide and a diacid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. Under nitrogen protection, the mixture was heated to 100°C and stirred for 4 hours. After the reaction was completed, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The diacid was adipic acid. The molar ratio of triaminemethylphosphine oxide to the diacid was 1:1. The molar ratio of the diacid, N-methylpyrrolidone, pyridine, and triphenyl phosphite was 10 mmol: 20 mL: 4 mL: 4 mL.

[0033] Vinyl epoxy silicone resin is prepared through the following steps: Epoxysilane and alkoxysilane were added to an aqueous ethanol solution, heated to 70°C, and stirred for 10 min. Dibutyltin dilaurate was added, and the reaction was stirred for 4 h. Vinylsilane was then added, and the reaction continued for 3 h. After the reaction was completed, small molecule byproducts were removed by rotary evaporation to obtain vinyl epoxy silicone resin. The molar ratio of epoxysilane, alkoxysilane, and vinylsilane was 0.4:3:0.1; the amount of dibutyltin dilaurate added was 1% of the total amount of silane. The epoxysilane was 3-glycidyl etheroxypropylmethyldiethoxysilane; the alkoxysilane was dimethyldimethoxysilane; and the vinylsilane was dimethylethoxyvinylsilane.

[0034] Example 2 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 200℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 3 minutes. Vinyl epoxy silicone resin was added and mixed for 5 minutes. Phosphorus-containing polyamide was added and mixed for another 5 minutes. The temperature was lowered to 110℃, and dicumyl peroxide was added and mixed for 3 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 2 parts vinyl epoxy silicone resin, 18 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 200℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0035] The phosphorus-containing polyamide is the same as in Example 1.

[0036] The vinyl epoxy silicone resin used is the same as in Example 1.

[0037] Example 3 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 2.5 parts vinyl epoxy silicone resin, 17.5 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0038] The phosphorus-containing polyamide is the same as in Example 1.

[0039] The vinyl epoxy silicone resin used is the same as in Example 1.

[0040] Example 4 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 3 parts vinyl epoxy silicone resin, 17 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0041] The phosphorus-containing polyamide is the same as in Example 1.

[0042] The vinyl epoxy silicone resin used is the same as in Example 1.

[0043] Example 5 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 4 parts vinyl epoxy silicone resin, 16 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0044] The phosphorus-containing polyamide is the same as in Example 1.

[0045] The vinyl epoxy silicone resin used is the same as in Example 1.

[0046] Example 6 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 2 parts vinyl epoxy silicone resin, 18 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0047] The phosphorus-containing polyamide is prepared through the following steps: Triaminemethylphosphine oxide and a diacid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. Under nitrogen protection, the mixture was heated to 100°C and stirred for 4 hours. After the reaction was completed, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The diacid was sebacic acid. The molar ratio of triaminemethylphosphine oxide to the diacid was 1:1. The molar ratio of the diacid, N-methylpyrrolidone, pyridine, and triphenyl phosphite was 10 mmol: 20 mL: 4 mL: 4 mL.

[0048] The vinyl epoxy silicone resin used is the same as in Example 1.

[0049] Example 7 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 2 parts vinyl epoxy silicone resin, 18 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0050] The phosphorus-containing polyamide is prepared through the following steps: Triaminemethylphosphine oxide and a diacid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. Under nitrogen protection, the mixture was heated to 100°C and stirred for 4 hours. After the reaction was completed, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The diacid was dodecanoic acid. The molar ratio of triaminemethylphosphine oxide to the diacid was 1:1. The molar ratio of the diacid, N-methylpyrrolidone, pyridine, and triphenyl phosphite was 10 mmol: 20 mL: 4 mL: 4 mL.

[0051] The vinyl epoxy silicone resin used is the same as in Example 1.

[0052] Example 8 This embodiment provides a low-smoke halogen-free flame-retardant polyolefin-sheathed environmentally friendly cable, comprising a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body, the cable being prepared through the following steps: The temperature was set at 180℃ and the rotation speed at 50 rpm. Low-density polyethylene and antioxidant were added and mixed for 2 minutes. Vinyl epoxy silicone resin was added and mixed for 3 minutes. Phosphorus-containing polyamide was added and mixed for another 3 minutes. The temperature was lowered to 105℃, and dicumyl peroxide was added and mixed for 2 minutes to obtain the polyolefin sheath material. By weight, the composition was: 80 parts low-density polyethylene, 0.3 parts antioxidant 1010, 2 parts vinyl epoxy silicone resin, 18 parts phosphorus-containing polyamide, and 1.3 parts dicumyl peroxide. Polyolefin sheath material is melt-extruded at a temperature of 180℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

[0053] The phosphorus-containing polyamide is the same as in Example 1.

[0054] Vinyl epoxy silicone resin is prepared through the following steps: Epoxysilane and alkoxysilane were added to an aqueous ethanol solution, heated to 75°C, and stirred for 15 min. Dibutyltin dilaurate was added, and the reaction was stirred for 5 h. Vinylsilane was then added, and the reaction continued for 4 h. After the reaction was completed, small molecule byproducts were removed by rotary evaporation to obtain vinyl epoxy silicone resin. The molar ratio of epoxysilane, alkoxysilane, and vinylsilane was 0.5:3:0.3; the amount of dibutyltin dilaurate added was 1.5% of the total amount of silane. The epoxysilane was 3-glycidoxypropylmethyldimethoxysilane; the alkoxysilane was diethoxydimethylsilane; and the vinylsilane was dimethylethoxyvinylsilane.

[0055] Comparative Example 1 Compared with Example 1, this comparative example replaces the phosphorus-containing polyamide with an equal amount of vinyl epoxy silicone resin, while keeping the other raw materials and preparation process the same as in Example 1.

[0056] Comparative Example 2 Compared with Example 1, this comparative example replaces the phosphorus-containing polyamide with polyamide, which is prepared by the following steps: Dodecanediamine and dodecanoic acid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. Under nitrogen protection, the mixture was heated to 100°C and stirred for 4 hours. After the reaction was complete, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain polyamide. The molar ratio of dodecanediamine to dodecanoic acid was 1:1. The molar ratio of dodecanoic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite was 10 mmol: 20 mL: 4 mL: 4 mL. The remaining raw materials and preparation process were the same as in Example 1.

[0057] Comparative Example 3 This comparative example differs from Example 1 in that the phosphorus-containing polyamide is prepared via the following steps: Bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide and a diacid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. Under nitrogen protection, the mixture was heated to 100°C and stirred for 4 hours. After the reaction was completed, the reaction solution was poured into water, filtered, and the resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The diacid was adipic acid. The molar ratio of bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide to the diacid was 1:1. The molar ratio of the diacid, N-methylpyrrolidone, pyridine, and triphenyl phosphite was 10 mmol: 20 mL: 4 mL: 4 mL.

[0058] The remaining raw materials and preparation process are the same as in Example 1.

[0059] Comparative Example 4 The difference between this comparative example and Example 1 lies in the preparation process of the vinyl epoxy silicone resin. Specifically: Epoxysilane and alkoxysilane were added to an aqueous ethanol solution, heated to 70°C, and stirred for 10 min. Dibutyltin dilaurate was added, and the reaction was stirred for 4 h. Vinylsilane was then added, and the reaction continued for 3 h. After the reaction was completed, small molecule byproducts were removed by rotary evaporation to obtain vinyl epoxy silicone resin. The molar ratio of epoxysilane, alkoxysilane, and vinylsilane was 2:3:0.1; the amount of dibutyltin dilaurate added was 1% of the total amount of silane. The epoxysilane was 3-glycidyl etheroxypropylmethyldiethoxysilane; the alkoxysilane was dimethyldimethoxysilane; and the vinylsilane was dimethylethoxyvinylsilane.

[0060] The remaining raw materials and preparation process are the same as in Example 1.

[0061] The sheath materials of Examples 1-8 and Comparative Examples 1-4 were subjected to performance tests, including tensile properties and limiting oxygen index. Tensile properties were tested according to GB / T 528-2009 standard; limiting oxygen index was tested according to GB / T2406.2-2009. The sample thickness was 4.0 mm. The results are shown in Table 1. Table 1 The test results show that controlling the ratio of vinyl epoxy silicone resin to phosphorus-containing polyamide can improve the limiting oxygen index of the polyolefin sheath material. The molecular-level synergistic flame-retardant effect of vinyl epoxy silicone resin and phosphorus-containing polyamide can also prevent flame retardant migration, thus maintaining relatively stable tensile strength. Vinyl epoxy silicone resin acts as a "compatibility agent" between the phosphorus-containing polyamide and the polyolefin resin, improving interfacial bonding. According to the results of Example 1 and Comparative Example 4, the proportion of epoxy groups in the vinyl epoxy silicone resin should not be too high, as this will reduce the dispersibility of the raw materials and affect the overall performance of the material. According to the results of Example 1 and Comparative Examples 1-2, the improvement in flame-retardant performance of the material by a single vinyl epoxy silicone resin and conventional polyamide is limited. A comparison between Example 1 and Comparative Example 3 shows that different types of phosphorus-containing polyamides have different degrees of improvement on the material; polyamides with a certain degree of branching can better improve the mechanical and flame-retardant properties of the material.

[0062] Low-temperature impact performance tests were conducted on the samples from Example 1 and Comparative Examples 1-4. The low-temperature impact performance test involved immersing the sheath material sample in a freezing medium at -70°C for 3 minutes to measure its notched impact strength. The samples were prepared as 80mm × 10mm × 4mm samples with a notch angle of 45°.o The impact depth was 2 mm, the impact velocity was 3.5 m / s, and the impact energy was 2.75 J. The volume resistivity of the samples was tested according to GB / T 31838.2-2019. Each sample was tested in triplicate, and the average value was taken. The test results are shown in Table 2 below: Table 2 The test results show that the sheath material prepared by this invention has good low-temperature resistance. The introduction of vinyl epoxy silicone resin improves the interfacial bonding between the two phases. Organosilicon segments and phosphorus-containing polyamide segments can be introduced into the polyethylene matrix through copolymerization or block polymerization to form a network structure with a certain degree of elasticity. This structure can effectively disperse stress and reduce brittle fracture caused by stress concentration at low temperatures. According to the test results of Example 1 and Comparative Examples 1-4, the addition of vinyl epoxy silicone resin and phosphorus-containing polyamide reduces the resistivity of the material. However, the branched structure of the phosphorus-containing polyamide and the high degree of molecular chain entanglement of the vinyl epoxy silicone resin disrupt the regularity of the polymer backbone, hindering the close packing of molecular chains, leading to decreased crystallinity and inhibiting carrier migration. Utilizing the synergistic effect of phosphorus-containing polyamide and silicone resin, the volume resistivity of the material is maintained at 10 Ω·cm. 15 Ω·cm or higher, meeting cable insulation requirements.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low smoke, halogen-free, flame-retardant, polyolefin sheathed, environmentally friendly cable, characterized in that, The cable includes a low-smoke halogen-free flame-retardant polyolefin sheath and a cable body. The low-smoke halogen-free flame-retardant polyolefin sheath is made of polyolefin sheath material, which is prepared by the following steps: setting the temperature to 180-200℃, adding polyolefin resin and antioxidant and mixing for 2-3 minutes, adding vinyl epoxy silicone resin and mixing for 3-5 minutes, adding phosphorus-containing polyamide and continuing to mix for 3-5 minutes, cooling to 105-110℃, adding crosslinking agent and mixing for 2-3 minutes to obtain the polyolefin sheath material. By weight, the composition is: 80 parts polyolefin resin, 0.3-0.4 parts antioxidant, 2-4 parts vinyl epoxy silicone resin, 16-18 parts phosphorus-containing polyamide, and 1.3-1.5 parts crosslinking agent. The phosphorus-containing polyamide is prepared by the following steps: Triamine methylphosphine oxide and a dicarboxylic acid were added to N-methylpyrrolidone, pyridine and triphenyl phosphite. Under nitrogen protection, the temperature was raised to 100°C and the mixture was stirred for 4-5 hours. After the reaction was completed, the reaction solution was poured into water and filtered. The resulting polymer was washed with ethanol and dried to obtain phosphorus-containing polyamide. The dicarboxylic acid is one of adipic acid, sebacic acid, and dodecanoic acid; the molar ratio of triaminemethylphosphine oxide to the dicarboxylic acid is 1:1; the ratio of the amount of dicarboxylic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite is 10 mmol: 20 mL: 4 mL: 4 mL; Vinyl epoxy silicone resin is prepared by the following steps: Epoxysilane and alkoxysilane are added to an aqueous ethanol solution, heated to 70-75℃, stirred for 10-15 min, an organotin catalyst is added, and the reaction is stirred for 4-5 h. Vinylsilane is added and the reaction is continued for 3-4 h. After the reaction is completed, small molecule byproducts are removed by rotary evaporation to obtain vinyl epoxy silicone resin. The molar ratio of epoxysilane, alkoxysilane and vinylsilane is 0.4-0.5:3:0.1-0.3; The amount of organotin catalyst added is 1% to 2% of the total amount of silane.

2. The low smoke zero halogen flame retardant polyolefin sheath environment-friendly cable according to claim 1, characterized in that, The polyolefin resin is low-density polyethylene; the crosslinking agent is dicumyl peroxide.

3. The low smoke zero halogen flame retardant polyolefin jacketed environmentally friendly cable according to claim 1, wherein, The vinyl epoxy silicone resin is prepared by hydrolysis and condensation of epoxy silane, alkoxy silane and vinyl silane.

4. The low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable according to claim 3, characterized in that, The epoxy silane is one of 3-glycidyl etheroxypropylmethyldiethoxysilane and 3-glycidyl etheroxypropylmethyldimethoxysilane; The alkoxysilane is one of dimethyldimethoxysilane and diethoxydimethylsilane; The vinylsilane is one of dimethylethoxyvinylsilane and trivinylethoxysilane.

5. A method for preparing a low-smoke, halogen-free, flame-retardant polyolefin-sheathed environmentally friendly cable as described in any one of claims 1-4, characterized in that, The process includes the following steps: the polyolefin sheath material is melt-extruded at a temperature of 180-200℃ and uniformly extruded onto the surface of the cable body. After cooling, a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable is obtained.

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