Low-smoke halogen-free flame-retardant polyolefin sheath environment-friendly cable and preparation method thereof

Abstract

The invention discloses a low-smoke halogen-free flame-retardant polyolefin sheath environment-friendly cable and a preparation method thereof, and belongs to the technical field of wire and cable materials, the cable comprises a low-smoke halogen-free flame-retardant polyolefin sheath and a cable main body, the low-smoke halogen-free flame-retardant polyolefin sheath is made of a polyolefin sheath material, and the low-smoke halogen-free flame-retardant polyolefin sheath is made of a halogen-free flame-retardant polyolefin sheath material. The polyolefin sheath material is prepared by the following steps: setting the temperature to be 180-200 DEG C, mixing polyolefin resin and an antioxidant, adding vinyl epoxy silicon resin for mixing, adding phosphorus-containing polyamide for continuous mixing, cooling to 105-110 DEG C, and adding a cross-linking agent for mixing to obtain the polyolefin sheath material. Through the molecular-level synergistic flame-retardant effect of the vinyl epoxy silicone resin and the phosphorus-containing polyamide, no additional flame retardant is needed, the addition of toxic flame retardants such as halogen is avoided, and toxic halogen hydride gas is not released. Through synergistic flame retardance of the vinyl epoxy silicone resin and the phosphorus-containing polyamide, the problem of poor flame retardance of the polyolefin sheath is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wire and cable materials, and in particular relates to a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable and a preparation method thereof. Background Art

[0002] In the wire and cable industry, the selection of flame-retardant wire and cable sheath materials is crucial. At present, flame-retardant wire and cable sheath materials are mostly polyvinyl chloride and polyolefin polymers with halogen-containing flame retardants. Polyvinyl chloride and traditional halogen-containing flame retardants will release a large amount of toxic gases when burned, which will have a great impact on the environment. When burning in a fire, they will release a large amount of toxic and corrosive gases and smoke, which seriously affect the escape of personnel and fire rescue work. Therefore, their use is subject to many restrictions, which limit their use.

[0003] To overcome these issues, 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), silicon-based flame retardants (such as silicone rubber and silicone resin), and intumescent flame retardants. These flame retardants work through various mechanisms, including vapor-phase flame retardancy, condensed-phase flame retardancy, and synergistic flame retardancy. However, practical applications still face numerous challenges. First, polyolefins, as non-polar, saturated carbon chain polymers, have poor compatibility with most flame retardants, leading to phase separation during blending, which affects the mechanical properties and flame retardant efficiency of the material and poses safety risks in practical applications. Second, achieving the desired flame retardant effect often requires a high proportion of flame retardant (typically 30% to 60%), which significantly reduces the material's mechanical properties and processing fluidity. Furthermore, some flame retardants (such as metal hydroxides) are prone to decomposition and inactivation during high-temperature processing, while phosphorus-based flame retardants pose migration and precipitation issues. Summary of the Invention

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

[0005] The purpose of the present invention can be achieved through the following technical solutions: A low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable comprises 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 a polyolefin sheath material, and the polyolefin sheath material is prepared by the following steps: setting the temperature to 180-200° C., adding a polyolefin resin and an antioxidant and kneading them for 2-3 minutes, adding a vinyl epoxy silicone resin and kneading them for 3-5 minutes, adding a phosphorus-containing polyamide and continuing to knead them for 3-5 minutes, cooling the temperature to 105-110° C., adding a cross-linking agent and kneading them for 2-3 minutes to obtain the polyolefin sheath material.

[0006] Furthermore, based on weight, the polyolefin resin comprises 80 parts, the antioxidant 0.3-0.4 parts, the vinyl epoxy silicone resin 2-4 parts, the phosphorus-containing polyamide 16-18 parts, and the cross-linking agent 1.3-1.5 parts.

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

[0008] Furthermore, the phosphorus-containing polyamide is prepared by the following steps: Triaminomethylphosphine oxide and dibasic acid are added to N-methylpyrrolidone, pyridine and triphenyl phosphite, and the temperature is raised to 100°C under nitrogen protection, and the reaction is stirred for 4-5 hours. After the reaction is completed, the reaction liquid is poured into water and filtered. The obtained polymer is washed with ethanol and dried to obtain phosphorus-containing polyamide.

[0009] Furthermore, the dibasic acid is one of adipic acid, sebacic acid and dodecanedioic acid; the molar ratio of triaminemethylphosphine oxide to the dibasic acid is 1:1; and the usage ratio of the dibasic 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: Add epoxysilane and alkoxysilane to an ethanol aqueous solution, heat to 70-75°C, stir for 10-15 minutes, add an organic tin catalyst, stir and react for 4-5 hours, add vinyl silane and continue to react for 3-4 hours. After the reaction is completed, remove small molecular by-products 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 epoxysilane is one of 3-glycidyloxypropylmethyldiethoxysilane and 3-glycidyloxypropyltetramethyldimethoxysilane; The alkoxysilane is one of dimethyldimethoxysilane and diethoxydimethylsilane; The vinyl silane is one of dimethylethoxyvinyl silane and trivinylethoxysilane.

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

[0015] Beneficial effects of the present invention: The present invention provides an environmentally friendly low-smoke, halogen-free, flame-retardant polyolefin sheathed cable. The cable includes a low-smoke, halogen-free, flame-retardant polyolefin sheath made of a polyolefin sheath material. In the process of preparing 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, the addition of additional flame retardants is unnecessary, the addition of toxic flame retardants such as halogens is avoided, and toxic hydrogen halide gas is not released. Furthermore, through the synergistic flame retardancy of the vinyl epoxy silicone resin and phosphorus-containing polyamide, the oxygen index can be increased to over 30.5%, significantly superior to conventional polyolefin materials, solving the problem of poor flame retardancy of the polyolefin sheath. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall 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 the present application.

[0018] In a first aspect, an embodiment of the present 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, wherein the low-smoke, halogen-free, flame-retardant polyolefin sheath is made of a polyolefin sheath material, and the polyolefin sheath material is prepared by the following steps: Set the temperature to 180-200°C, 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 to 105-110°C, add crosslinking agent and mix for 2-3 minutes to obtain polyolefin sheath material.

[0019] In some specific embodiments, based on weight parts, the polyolefin resin is 80 parts, the antioxidant 1010 is 0.3-0.4 parts, the vinyl epoxy silicone resin is 24 parts, the phosphorus-containing polyamide is 16-18 parts, and the cross-linking agent is 1.3-1.5 parts.

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

[0021] In some specific embodiments, the phosphorus-containing polyamide is prepared by the following steps: Triaminomethylphosphine oxide and dibasic acid are added to N-methylpyrrolidone, pyridine and triphenyl phosphite, and the temperature is raised to 100°C under nitrogen protection, and the reaction is stirred for 4-5 hours. After the reaction is completed, the reaction liquid is poured into water and filtered. The obtained polymer is washed with ethanol and dried to obtain phosphorus-containing polyamide.

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

[0023] Triaminomethylphosphine oxide (TMPO) was synthesized using a conventional method (Shaow 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). The following steps were used to synthesize TMPO: TMPO and methyl carbamate were mixed in a molar ratio of 1:8 and reacted at 107°C for 2 hours. After the reaction, the mixture was diluted with water, and 25% ammonia was added, followed by stirring for 6 hours. The mixture was dried under vacuum at room temperature and oxidized with 30% hydrogen peroxide solution. The oxidized product was mixed with calcium hydroxide and water, heated to reflux for 5 hours, and then carbon dioxide was introduced until neutral. After cooling, the mixture was filtered, and the filtrate was concentrated by rotary evaporation, then ethanol was added and filtered. The filtrate was then rotary evaporated to remove the ethanol, yielding TMPO. The ratio of TMPO to ammonia solution, hydrogen peroxide solution, and calcium hydroxide was 10 g:20 mL:15 mL:5 g.

[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: Add epoxysilane and alkoxysilane to an ethanol aqueous solution, heat to 70-75°C, stir for 10-15 minutes, add an organic tin catalyst, stir and react for 4-5 hours, add vinyl silane and continue to react for 3-4 hours. After the reaction is completed, remove small molecular by-products 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; and the amount of the organic tin catalyst added is 1% to 2% of the total amount of silane.

[0027] In some specific embodiments, the epoxysilane is one of 3-glycidyloxypropylmethyldiethoxysilane and 3-glycidyloxypropyltetramethyldimethoxysilane; The alkoxysilane is one of dimethyldimethoxysilane and diethoxydimethylsilane; The vinyl silane is one of dimethylethoxyvinyl silane and trivinylethoxysilane.

[0028] The second aspect of the embodiment of the present application provides a method for preparing a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable, comprising the following steps: melt-extruding the polyolefin sheath material at a temperature of 180-200°C, uniformly extruding it on 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, and the insulation layer is formed by wrapping an insulation material around the conductor using an extruder, and the conductor is copper or aluminum.

[0030] The following is a detailed description with reference to the embodiments.

[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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 2 parts, the phosphorus-containing polyamide is 18 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0032] Wherein, the phosphorus-containing polyamide is prepared by the following steps: Triaminomethylphosphine oxide and a dibasic acid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. The temperature was raised to 100°C under nitrogen and stirred for 4 hours. After the reaction, the reaction solution was poured into water and filtered. The resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The dibasic acid was adipic acid, and the molar ratio of triaminomethylphosphine oxide to the dibasic acid was 1:1. The dibasic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite were used in a ratio of 10 mmol:20 mL:4 mL:4 mL.

[0033] Wherein, vinyl epoxy silicone resin is prepared by the following steps: Epoxysilane and alkoxysilane were added to an ethanol-water solution, heated to 70°C, and stirred for 10 minutes. Dibutyltin dilaurate was then added and allowed to react with stirring for 4 hours. Vinylsilane was then added and the reaction continued for 3 hours. After the reaction, small molecular weight byproducts were removed by rotary evaporation to obtain a 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 silane amount. The epoxysilane was 3-glycidoxypropylmethyldiethoxysilane; 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 is prepared by the following steps: Set the temperature to 200°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 3 minutes, add vinyl epoxy silicone resin and mix for 5 minutes, add phosphorus-containing polyamide and continue mixing for 5 minutes, cool to 110°C, add dicumyl peroxide and mix for 3 minutes to obtain a polyolefin sheath material. According to weight, the low-density polyethylene is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 2 parts, the phosphorus-containing polyamide is 18 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 200°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0035] Wherein, the phosphorus-containing polyamide is the same as that in Example 1.

[0036] Wherein, the vinyl epoxy silicone resin is the same as that 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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 2.5 parts, the phosphorus-containing polyamide is 17.5 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0038] Wherein, the phosphorus-containing polyamide is the same as that in Example 1.

[0039] Wherein, the vinyl epoxy silicone resin is the same as that 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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 3 parts, the phosphorus-containing polyamide is 17 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0041] Wherein, the phosphorus-containing polyamide is the same as that in Example 1.

[0042] Wherein, the vinyl epoxy silicone resin is the same as that 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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 4 parts, the phosphorus-containing polyamide is 16 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0044] Wherein, the phosphorus-containing polyamide is the same as that in Example 1.

[0045] Wherein, the vinyl epoxy silicone resin is the same as that 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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 2 parts, the phosphorus-containing polyamide is 18 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0047] Wherein, the phosphorus-containing polyamide is prepared by the following steps: Triaminomethylphosphine oxide and a dibasic acid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. The temperature was raised to 100°C under nitrogen and stirred for 4 hours. After the reaction, the reaction solution was poured into water and filtered. The resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The dibasic acid was sebacic acid. The molar ratio of triaminomethylphosphine oxide to the dibasic acid was 1:1. The dibasic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite were used in a ratio of 10 mmol:20 mL:4 mL:4 mL.

[0048] Wherein, the vinyl epoxy silicone resin is the same as that 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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 2 parts, the phosphorus-containing polyamide is 18 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0050] Wherein, the phosphorus-containing polyamide is prepared by the following steps: Triaminomethylphosphine oxide and a dibasic acid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. The temperature was raised to 100°C and stirred for 4 hours under nitrogen. After the reaction, the reaction solution was poured into water and filtered. The resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The dibasic acid was dodecanedioic acid. The molar ratio of triaminomethylphosphine oxide to the dibasic acid was 1:1. The dibasic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite were used in a ratio of 10 mmol:20 mL:4 mL:4 mL.

[0051] Wherein, the vinyl epoxy silicone resin is the same as that 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 is prepared by the following steps: Set the temperature to 180°C and the rotation speed to 50 rpm, add low-density polyethylene and antioxidant and mix for 2 minutes, add vinyl epoxy silicone resin and mix for 3 minutes, add phosphorus-containing polyamide and continue mixing for 3 minutes, cool to 105°C, add dicumyl peroxide and mix for 2 minutes to obtain a polyolefin sheath material. In parts by weight, the low-density polyethylene (LDPE) is 80 parts, the antioxidant 1010 is 0.3 parts, the vinyl epoxy silicone resin is 2 parts, the phosphorus-containing polyamide is 18 parts, and the dicumyl peroxide is 1.3 parts. The polyolefin sheath material is melt-extruded at a temperature of 180°C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

[0053] Wherein, the phosphorus-containing polyamide is the same as that in Example 1.

[0054] Wherein, vinyl epoxy silicone resin is prepared by the following steps: Epoxysilane and alkoxysilane were added to an ethanol-water solution, heated to 75°C, stirred for 15 minutes, and then dibutyltin dilaurate was added. The reaction was stirred for 5 hours. Vinylsilane was added and the reaction continued for 4 hours. After the reaction, the small molecular weight byproducts were removed by rotary evaporation to obtain a 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 silane amount. The epoxysilane was 3-glycidyloxypropyltetramethyldimethoxysilane; 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, and the remaining raw materials and preparation process remain the same as those in Example 1.

[0056] Comparative Example 2 Compared with Example 1, this comparative example replaces the phosphorus-containing polyamide with polyamide, and the polyamide is prepared by the following steps: Dodecanediamine and dodecanedioic acid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. The temperature was raised to 100°C under nitrogen and stirred for 4 hours. After the reaction, the reaction solution was poured into water and filtered. The resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The molar ratio of dodecanediamine to dodecanedioic acid was 1:1. The ratio of dodecanedioic 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 Compared with Example 1, the phosphorus-containing polyamide in this comparative example is different. The phosphorus-containing polyamide is prepared by the following steps: Bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide and a dibasic acid were added to N-methylpyrrolidone, pyridine, and triphenyl phosphite. The temperature was raised to 100°C and stirred for 4 hours under nitrogen. After the reaction, the reaction solution was poured into water and filtered. The resulting polymer was washed with ethanol and dried to obtain a phosphorus-containing polyamide. The dibasic acid was adipic acid. The molar ratio of bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide to the dibasic acid was 1:1. The amount ratio of the dibasic acid, N-methylpyrrolidone, pyridine, and triphenyl phosphite was 10 mmol:20 mL:4 mL:4 mL.

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

[0059] Comparative Example 4 Compared with Example 1, this comparative example differs in that the preparation process of the vinyl epoxy silicone resin is different: Epoxysilane and alkoxysilane were added to an ethanol-water solution, heated to 70°C, stirred for 10 minutes, and then dibutyltin dilaurate was added. The reaction was stirred for 4 hours. Vinylsilane was added and the reaction continued for 3 hours. After the reaction, the small molecular weight byproducts were removed by rotary evaporation to obtain a 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 silane amount. The epoxysilane was 3-glycidoxypropylmethyldiethoxysilane; the alkoxysilane was dimethyldimethoxysilane; and the vinylsilane was dimethylethoxyvinylsilane.

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

[0061] The sheath materials of Examples 1-8 and Comparative Examples 1-4 were tested for tensile properties and limiting oxygen index (LOI). Tensile properties were tested according to GB / T 528-2009, while LOI was tested according to GB / T 2406.2-2009. The samples were 4.0 mm thick. The results are shown in Table 1. Table 1 According to the test results, by controlling the ratio of vinyl epoxy silicone resin and phosphorus-containing polyamide, the limiting oxygen index of the polyolefin sheath material can be improved. The molecular-level synergistic flame retardant effect of vinyl epoxy silicone resin and phosphorus-containing polyamide can also avoid the problem of flame retardant migration, thereby maintaining a relatively stable tensile strength. Vinyl epoxy silicone resin acts as a "compatibility agent" between phosphorus-containing polyamide and polyolefin resin to enhance interfacial binding. According to the results of Example 1 and Comparative Example 4, the proportion of epoxy groups in vinyl epoxy silicone resin should not be too high. Too high will lead to a decrease in the dispersibility of the raw materials, thereby affecting the overall performance of the material. According to the results of Example 1 and Comparative Example 1-Comparative Example 2, a single vinyl epoxy silicone resin and conventional polyamide have limited improvement in the flame retardant properties of the material. According to the comparison of Example 1 and Comparative Example 3, different types of phosphorus-containing polyamides have different degrees of improvement for the material. Polyamides with a certain degree of branching can better enhance the mechanical properties and flame retardant properties of the material.

[0062] The samples in Example 1 and Comparative Examples 1 to 4 were subjected to a low-temperature impact performance test. The low-temperature impact performance test is to test the notched impact strength of the sheath material sample at -70°C (the sample is immersed in a freezing medium at -70°C for 3 minutes). The sample is made into a sample of 80mm×10mm×4mm, with a notch angle of 45o , depth of 2mm, impact velocity of 3.5 m / s, impact energy of 2.75 J; and the volume resistivity of the sample was tested according to GB / T 31838.2-2019. Each sample was tested in parallel 3 times and the average value was taken. The test results are shown in Table 2 below:

[0063] According to the test results, the sheath material prepared by the present invention has good low-temperature resistance, wherein the introduction of vinyl epoxy silicone resin can improve the interface bonding between the two phases, and the organic silicon segment and the phosphorus-containing polyamide segment can be introduced into the polyethylene matrix by copolymerization or block, forming a network structure with a certain 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 will reduce the resistivity of the material, but the branched structure of phosphorus-containing polyamide and the molecular chain entanglement of vinyl epoxy silicone resin are many, which destroy the regularity of the polymer main chain, hinder the close stacking of the molecular chain, lead to a decrease in crystallinity and inhibit carrier migration, and utilize the synergistic effect of phosphorus-containing polyamide and silicone resin to keep the volume resistivity of the material at 10 15 Ω·cm and above, meeting the cable insulation requirements.

[0064] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0065] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention 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 comprises 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 a polyolefin sheath material. The polyolefin sheath material is prepared by the following steps: setting the temperature to 180-200°C, adding a polyolefin resin and an antioxidant and kneading for 2-3 minutes, adding a vinyl epoxy silicone resin and kneading for 3-5 minutes, adding a phosphorus-containing polyamide and continuing to knead for 3-5 minutes, cooling to 105-110°C, adding a cross-linking agent and kneading for 2-3 minutes to obtain the polyolefin sheath material.

2. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 1, characterized in that: In parts by weight, the composition includes 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 cross-linking agent.

3. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 1, characterized in that: The polyolefin resin is low-density polyethylene; the cross-linking agent is dicumyl peroxide.

4. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 1, characterized in that: The phosphorus-containing polyamide is prepared by the following steps: Triaminomethylphosphine oxide and dibasic acid are added to N-methylpyrrolidone, pyridine and triphenyl phosphite, and the temperature is raised to 100°C under nitrogen protection, and the reaction is stirred for 4-5 hours. After the reaction is completed, the reaction liquid is poured into water and filtered. The obtained polymer is washed with ethanol and dried to obtain phosphorus-containing polyamide.

5. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 4, characterized in that: The dibasic acid is one of adipic acid, sebacic acid and dodecanedioic acid; the molar ratio of triaminemethylphosphine oxide to the dibasic acid is 1:1; and the amount ratio of the dibasic acid, N-methylpyrrolidone, pyridine and triphenyl phosphite is 10 mmol:20 mL:4 mL:4 mL.

6. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 1, characterized in that: The vinyl epoxy silicone resin is prepared by hydrolyzing and condensing epoxy silane, alkoxy silane and vinyl silane.

7. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 1, characterized in that: Vinyl epoxy silicone resin is prepared by the following steps: Add epoxysilane and alkoxysilane to an ethanol aqueous solution, heat to 70-75°C, stir for 10-15 minutes, add an organic tin catalyst, stir and react for 4-5 hours, add vinyl silane and continue to react for 3-4 hours. After the reaction is completed, remove small molecular by-products by rotary evaporation to obtain vinyl epoxy silicone resin.

8. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 6, characterized in that: 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.

9. The low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to claim 6, characterized in that: The epoxy silane is one of 3-glycidyloxypropylmethyldiethoxysilane and 3-glycidyloxypropyltetramethyldimethoxysilane; The alkoxysilane is one of dimethyldimethoxysilane and diethoxydimethylsilane; The vinyl silane is one of dimethylethoxyvinyl silane and trivinylethoxysilane.

10. A method for preparing a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: the polyolefin sheath material is melt-extruded at a temperature of 180-200 DEG C, uniformly extruded on the surface of the cable body, and cooled to obtain a low-smoke, halogen-free, flame-retardant polyolefin sheathed environmentally friendly cable.

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