A polyvinyl chloride-based flame-retardant cable sheath material and a method for producing the same

Abstract

This invention belongs to the field of cable sheath technology, specifically relating to a polyvinyl chloride (PVC) flame-retardant cable sheath material and its preparation method. The PVC flame-retardant cable sheath material, by weight, comprises the following raw materials: 100 parts modified PVC, 25-35 parts plasticizer, 15-25 parts filler, 8-15 parts modified flame retardant, 5-10 parts stabilizer, 1-2 parts lubricant, and 0.5-1.5 parts antioxidant. This invention mainly improves the flame-retardant performance of the PVC flame-retardant cable sheath material by modifying PVC with terminal thiol hyperbranched castor oil and branched polythiols, and by modifying magnesium hydroxide with vinyl polysiloxane. This also improves its low-temperature resistance. The PVC flame-retardant cable sheath material provided by this invention can be used for extended periods in environments below -50°C, and has broad application prospects in Northeast China, Inner Mongolia, and Northwest China.

Description

Technical Field

[0001] This invention belongs to the field of cable sheath technology, specifically relating to a polyvinyl chloride flame-retardant cable sheath material and its preparation method. Background Technology

[0002] Cable sheaths are the first line of defense between the cable's internal structure and the external environment, and are crucial to the cable's operational reliability. Currently, cable sheath materials mainly include polypropylene, polyvinyl chloride, ethylene-vinyl acetate copolymer, and polyethylene. Among these, polyvinyl chloride is the most widely used cable sheath due to its high cost-effectiveness, good flexibility, and ease of installation.

[0003] Polyvinyl chloride (PVC) can suppress the concentration of combustible gases and reduce the intensity of combustion to a certain extent, but its flame retardant effect is still relatively limited. Therefore, in order to improve the flame retardant performance of cables, flame retardants are often added to modify them. However, the balance between flame retardant efficiency and mechanical properties has not been fully resolved, and high addition amounts often lead to the material becoming hard and brittle.

[0004] Most of the Northeast, Inner Mongolia, and Northwest regions are located in high-altitude and cold areas, where winter temperatures can reach -50°C. Improving the flame-retardant effect of cable sheath materials while enhancing their low-temperature reliability has become a major technical problem that urgently needs to be solved.

[0005] Chinese Patent Publication No. CN 117986773 A discloses a PVC cable sheath material comprising the following raw materials in parts by weight: 100 parts polyvinyl chloride resin; 10-15 parts silicone-modified polyurethane elastomer; 15-20 parts plasticizer; 1-1.4 parts lubricant; 7-8 parts stabilizer; 0.8-1 part antioxidant; 0.8-1 part anti-aging agent; 15-17 parts filler. Under nitrogen protection, 5-hydroxypentanal, triethylamine, and ethyl acetate are mixed, and diphenyl chlorophosphate is added to obtain an intermediate product. The intermediate product is then added to ethanol, and p-aminophenol is added to react and obtain a flame retardant. The flame retardant and epoxy cashew phenol are added to ethanol, and transition metal ions are added to obtain a plasticizer. By combining flame retardancy and plasticization, the molecular weight of the plasticizer is increased, improving its migration resistance. Improved migration resistance reduces intermolecular forces in PVC and improves the low-temperature impact resistance of the cable material. However, the oxygen index of this technology can only reach about 29%.

[0006] Chinese Patent CN120399369B discloses a low-temperature resistant, flame-retardant, and UV-resistant PVC cable sheath composition, its preparation method, and the cable thereof. This composition uses polyvinyl chloride (PVC) as a matrix, supplemented with chlorinated polyethylene elastomer, environmentally friendly plasticizers, and calcium-zinc stabilizers. It also incorporates nano-sized magnesium hydroxide, zinc stannate, passivated zinc borate, sodium tungstate, and modified montmorillonite to form a multi-component synergistic flame-retardant system, significantly improving the material's flame retardancy, low smoke emission, and thermal stability. Simultaneously, the synergistic effect of UV absorbers and antioxidants enhances the material's weather resistance and service life. The resulting cable sheath material exhibits excellent low-temperature flexibility, flame-retardant and smoke-suppressing properties, and UV aging resistance, making it suitable for high-performance cable applications in harsh environments. However, the embrittlement temperature of this technical solution only reaches -40℃. Summary of the Invention

[0007] The purpose of this invention is to provide a polyvinyl chloride flame-retardant cable sheath material and its preparation method.

[0008] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a polyvinyl chloride flame-retardant cable sheath material, which, by weight, comprises the following raw materials: 100 parts modified polyvinyl chloride, 25-35 parts plasticizer, 15-25 parts filler, 8-15 parts modified flame retardant, 5-10 parts stabilizer, 1-2 parts lubricant, and 0.5-1.5 parts antioxidant. The modified polyvinyl chloride is prepared by dissolving polyvinyl chloride resin powder in solvent A, adding terminal thiol hyperbranched castor oil, branched polythiol B and acid-binding agent, reacting under nitrogen protection, and then performing post-treatment after the reaction is completed to obtain the product.

[0009] Furthermore, solvent A is cyclohexanone.

[0010] Furthermore, the branched polythiol B is 2,3-dithio(2-mercapto)-1-propanethiol.

[0011] Furthermore, the acid-binding agent is potassium carbonate.

[0012] Furthermore, the mass ratio of the polyvinyl chloride resin powder, solvent A, terminal thiol hyperbranched castor oil, branched polythiol B, and acid-binding agent is 100:300-400:10-20:5-10:20-30.

[0013] Furthermore, the preparation method of the modified polyvinyl chloride is as follows: dissolve polyvinyl chloride powder in solvent A, add terminal thiol hyperbranched castor oil, branched polythiol B and acid-binding agent, and react at 50-70℃ for 8-15 hours under nitrogen protection. After the reaction is completed, remove the solvent, wash and dry to obtain the product. Furthermore, the preparation method of the terminal thiol hyperbranched castor oil is as follows: the double-bonded castor oil derivative and the branched polythiol A are mixed evenly in solvent B, and azobisisobutyronitrile is added under nitrogen protection. After the reaction is completed, the product is obtained by post-treatment.

[0014] Furthermore, the branched polythiothiool A is selected from at least one of pentaerythritol tetra(3-mercaptopropionate) and trimethylolpropane tri(3-mercaptopropionate).

[0015] Furthermore, the molar ratio of the double-bonded castor oil derivative to the branched polythiol A is 1:1-3.

[0016] Furthermore, solvent B is selected from at least one of tetrahydrofuran, dichloromethane, chloroform, and acetone.

[0017] Furthermore, the mass ratio of the double-bonded castor oil derivative, solvent B, and azobisisobutyronitrile is 100:1-2.

[0018] Furthermore, the amount of azobisisobutyronitrile added is 1-2% of the mass of the double-bonded castor oil derivative.

[0019] Furthermore, the preparation method of the terminal thiol hyperbranched castor oil is as follows: the double-bonded castor oil derivative and the branched polythiol A are mixed evenly in solvent B, and azobisisobutyronitrile is added under nitrogen protection. The mixture is reacted at 40-60℃ for 8-24 hours. After the reaction is completed, the solvent and unreacted substances are removed by rotary evaporation to obtain the final product.

[0020] Furthermore, the preparation method of the double-bonded castor oil derivative is as follows: ricinoleic acid and methacrylic anhydride are mixed, a polymerization inhibitor is added, the mixture is reacted, and methacrylic acid is removed by rotary evaporation to obtain the product.

[0021] Furthermore, the polymerization inhibitor is selected from at least one of hydroquinone, p-benzoquinone, methyl hydroquinone, p-hydroxyanisole, and p-methoxyphenol.

[0022] Furthermore, the molar ratio of ricinoleic acid to methacrylic anhydride is 1:2-5.

[0023] Furthermore, the mass ratio of the methacrylic anhydride to the polymerization inhibitor is 100:0.1-0.5.

[0024] Furthermore, the preparation method of the double-bonded castor oil derivative is as follows: ricinoleic acid and methacrylic anhydride are mixed, a polymerization inhibitor is added, and the mixture is reacted at 80-100℃ for 2-4 hours. The methacrylic acid is then removed by rotary evaporation to obtain the product.

[0025] Furthermore, the plasticizer is selected from at least one of tributyl acetylcitrate, dioctyl adipate, and epoxidized soybean oil.

[0026] Furthermore, the filler is selected from at least one of calcium carbonate, talc, and mica powder.

[0027] Furthermore, the modified flame retardant is obtained by reacting aluminum hydroxide containing carbon-carbon double bonds and vinyl polysiloxane.

[0028] Further, the modified flame retardant is prepared by mixing aluminum hydroxide, methacryloxysilane and an aqueous ethanol solution, reacting, filtering, washing and drying to obtain aluminum hydroxide containing carbon-carbon double bonds; mixing aluminum hydroxide containing carbon-carbon double bonds, vinyl polysiloxane and an aqueous ethanol solution, adding azobisisobutyronitrile under nitrogen protection, reacting, filtering, washing and drying to obtain the modified flame retardant.

[0029] Further, the methacryloyloxysilane is selected from at least one of 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyldimethoxysilane, methacryloyloxypropylmethyldiethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, methacryloyloxytrimethoxysilane, and methacryloyloxytriethoxysilane.

[0030] Furthermore, the mass fraction of the ethanol aqueous solution is 80-90%.

[0031] Further, the mass ratio of the aluminum hydroxide, the aqueous ethanol solution, and the methacryloxysilane is 1:20-40:0.1-0.2.

[0032] Furthermore, the molecular structural formula of the vinyl polysiloxane is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH).

[0033] Furthermore, the vinyl polysiloxane is V421-1300 from Shandong Dayi Chemical Co., Ltd., with a vinyl content of 0.0509-0.0623 mol / 100g and a viscosity of 1300±70 cps (25℃).

[0034] Furthermore, the mass ratio of the aluminum hydroxide containing carbon-carbon double bonds, vinyl polysiloxane, aqueous ethanol solution, and azobisisobutyronitrile is 1:0.1-0.4:20-40:0.01-0.04.

[0035] Further, the preparation method of the modified flame retardant is as follows: aluminum hydroxide, methacryloxysilane and ethanol aqueous solution are mixed and reacted at 70-75℃ for 4-6 hours, filtered, washed and dried to obtain aluminum hydroxide containing carbon-carbon double bonds; aluminum hydroxide containing carbon-carbon double bonds, vinyl polysiloxane and ethanol aqueous solution are mixed, azobisisobutyronitrile is added under nitrogen protection, and reacted at 65-75℃ for 24 hours, filtered, washed and dried to obtain the modified flame retardant.

[0036] Furthermore, the stabilizer is a calcium-zinc composite stabilizer.

[0037] Furthermore, the lubricant is selected from at least one of calcium stearate and polyethylene wax.

[0038] Furthermore, the antioxidant is selected from at least one of antioxidant 1010, antioxidant 246, antioxidant 168 and antioxidant BHT.

[0039] A second aspect of the present invention provides a method for preparing a polyvinyl chloride flame-retardant cable sheath material, comprising the following steps: Modified polyvinyl chloride, plasticizer, filler, modified flame retardant, stabilizer, lubricant and antioxidant are mixed and extruded into granules to obtain polyvinyl chloride flame retardant cable sheath material.

[0040] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: This invention provides a polyvinyl chloride (PVC) flame-retardant cable sheath material. Based on existing PVC flame-retardant cable sheath material formulations, this invention primarily improves the flame-retardant properties of the PVC flame-retardant cable sheath material by modifying PVC with terminal thiol hyperbranched castor oil and branched polythiols, and by modifying magnesium hydroxide with vinyl polysiloxane. This effectively enhances both the flame-retardant performance and low-temperature resistance of the PVC flame-retardant cable sheath material. The PVC flame-retardant cable sheath material provided by this invention can be used for extended periods in environments below -50°C, and has broad application prospects in Northeast China, Inner Mongolia, and Northwest China, as detailed below: The modified polyvinyl chloride (PVC) provided by this invention is obtained by co-modification with terminal thiol hyperbranched castor oil and branched polythiol B. The thiol groups in the terminal thiol hyperbranched castor oil and branched polythiol B can react with chlorine atoms in the PVC molecular chain, introducing hyperbranched castor oil into the PVC molecular chain and introducing carboxyl and hydroxyl groups, thereby improving the fluidity of the PVC molecular chain, increasing the inter-chain spacing, increasing the free volume between polymer molecules, and improving the low-temperature toughness of the sheath material. The modified flame retardant provided by this invention is composed of hydroxide containing carbon-carbon double bonds. The reaction of aluminum and vinyl polysiloxane yields a vinyl polysiloxane coating on the surface of magnesium hydroxide. This coating improves the dispersibility of magnesium hydroxide in the system and forms a synergistic flame retardant effect between Si and magnesium hydroxide. Simultaneously, the polysiloxane on the surface of magnesium hydroxide can interact with modified polyvinyl chloride containing hydroxyl and carboxyl groups. The compliant siloxane segments can interweave between polyvinyl chloride molecular chains, further increasing the distance between polyvinyl chloride molecular chains and weakening the strong polar interaction between polyvinyl chloride chain segments. Consequently, the embrittlement temperature of the polyvinyl chloride flame-retardant cable sheath material is ≤-60℃. Attached Figure Description

[0041] Figure 1 A photograph of a round cable with aluminum core, polyvinyl chloride insulation, and polyvinyl chloride sheath, prepared using the polyvinyl chloride flame-retardant cable sheath material of Example 3; Figure 2 The test results of the mechanical properties of the sheath of the round cable with aluminum core, polyvinyl chloride insulation, and polyvinyl chloride sheath prepared using the polyvinyl chloride flame-retardant cable sheath material of Example 3; Figure 3 The non-combustible experimental results of aluminum core PVC insulated PVC sheathed round cables prepared using the PVC flame-retardant cable sheath material of Example 3 are presented. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The sources of raw materials for the embodiments and comparative examples of the present invention are shown below: Polyvinyl chloride resin powder, with an average degree of polymerization of 950-1100 and a K value of 66-68, Zhongtai Chemical SG5; Aluminum hydroxide, 10000 mesh, Dongguan Hongtaiji Flame Retardant Materials Co., Ltd. Calcium-zinc composite stabilizer, Zanyu Technology Group Co., Ltd., HYCZ-105; Ricinoleic acid, purity ≥99%, Suzhou Yake Technology Co., Ltd.; The calcium carbonate is light calcium carbonate, with a mesh size of 3000, produced by Shandong Zhongtian Mining Co., Ltd. Pentaerythritol tetra(3-mercaptopropionate), CAS No.: 7575-23-7; Pusi (Wuxi) New Material Technology Co., Ltd. Example

[0044] This embodiment provides a polyvinyl chloride flame-retardant cable sheath material, which, by weight, includes the following raw materials: 100 parts modified polyvinyl chloride, 25 parts plasticizer, 15 parts filler, 8 parts modified flame retardant, 5 parts stabilizer, 1 part lubricant, and 0.5 parts antioxidant.

[0045] The specific preparation method of the modified polyvinyl chloride is as follows: 100 parts of polyvinyl chloride powder are dissolved in 250 parts of solvent A (cyclohexanone), 15 parts of terminal thiol hyperbranched castor oil, 8 parts of branched polythiol B (2,3-dithio(2-mercapto)-1-propanethiol) and 25 parts of acid-binding agent (potassium carbonate) are added, and the mixture is reacted at 60°C for 12 hours under nitrogen protection. After the reaction is completed, the solvent is removed, and the mixture is washed with a 65% (v / v) methanol aqueous solution and dried to obtain the final product.

[0046] The preparation method of the terminal thiol hyperbranched castor oil is as follows: the double-bonded castor oil derivative and branched polythiol A (pentaerythritol tetra(3-mercaptopropionate)) are mixed evenly in solvent B (tetrahydrofuran, the amount added is 10 times the total mass of the double-bonded castor oil derivative and branched polythiol A (pentaerythritol tetra(3-mercaptopropionate)) at a molar ratio of 1:2. Under nitrogen protection, azobisisobutyronitrile (the amount added is 1.5% of the mass of the double-bonded castor oil derivative) is added, and the reaction is carried out at 50°C for 12 hours. After the reaction is completed, the solvent and unreacted substances are removed by rotary evaporation to obtain the final product.

[0047] The preparation method of the double-bonded castor oil derivative is as follows: ricinoleic acid and methacrylic anhydride are mixed in a molar ratio of 1:3, a polymerization inhibitor (hydroquinone, the amount added is 0.3% of the mass of methacrylic anhydride) is added, the reaction is carried out at 90℃ for 3 hours, and methacrylic acid is removed by rotary evaporation to obtain the product.

[0048] The plasticizer is dioctyl adipate.

[0049] The filler is calcium carbonate.

[0050] The modified flame retardant is prepared by mixing 1 part aluminum hydroxide, 0.2 parts methacryloyloxysilane (3-methacryloyloxypropyltrimethoxysilane), and 30 parts ethanol aqueous solution (90% by mass), reacting at 75°C for 5 hours, filtering, washing, and drying to obtain aluminum hydroxide containing carbon-carbon double bonds; mixing 1 part aluminum hydroxide containing carbon-carbon double bonds, 0.3 parts vinyl polysiloxane, and 30 parts ethanol aqueous solution (90% by mass), adding 0.03 parts azobisisobutyronitrile under nitrogen protection, reacting at 70°C for 24 hours, filtering, washing, and drying to obtain the modified flame retardant.

[0051] The molecular structural formula of the vinyl polysiloxane is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH), produced by Shandong Dayi Chemical Co., Ltd., is V421-1300. It has a vinyl content of 0.0509-0.0623 mol / 100g and a viscosity of 1300±70 cps (25℃).

[0052] The stabilizer is a calcium-zinc composite stabilizer.

[0053] The lubricant is calcium stearate.

[0054] The antioxidant is antioxidant 1010.

[0055] The preparation method of the above-mentioned polyvinyl chloride flame-retardant cable sheath material includes the following steps: Modified polyvinyl chloride, plasticizer, filler, modified flame retardant, stabilizer, lubricant and antioxidant are mixed and extruded into granules to obtain polyvinyl chloride flame retardant cable sheath material. Example

[0056] This embodiment provides a polyvinyl chloride flame-retardant cable sheath material, which, by weight, includes the following raw materials: 100 parts modified polyvinyl chloride, 30 parts plasticizer, 20 parts filler, 12 parts modified flame retardant, 8 parts stabilizer, 1.5 parts lubricant, and 1 part antioxidant.

[0057] The specific preparation method of the modified polyvinyl chloride is as follows: 100 parts of polyvinyl chloride powder are dissolved in 250 parts of solvent A (cyclohexanone), 15 parts of terminal thiol hyperbranched castor oil, 8 parts of branched polythiol B (2,3-dithio(2-mercapto)-1-propanethiol) and 25 parts of acid-binding agent (potassium carbonate) are added, and the mixture is reacted at 60°C for 12 hours under nitrogen protection. After the reaction is completed, the solvent is removed, and the mixture is washed with a 65% (v / v) methanol aqueous solution and dried to obtain the final product.

[0058] The preparation method of the terminal thiol hyperbranched castor oil is as follows: the double-bonded castor oil derivative and branched polythiol A (pentaerythritol tetra(3-mercaptopropionate)) are mixed evenly in solvent B (tetrahydrofuran, the amount added is 10 times the total mass of the double-bonded castor oil derivative and branched polythiol A (pentaerythritol tetra(3-mercaptopropionate)) at a molar ratio of 1:2. Under nitrogen protection, azobisisobutyronitrile (the amount added is 1.5% of the mass of the double-bonded castor oil derivative) is added, and the reaction is carried out at 50°C for 12 hours. After the reaction is completed, the solvent and unreacted substances are removed by rotary evaporation to obtain the final product.

[0059] The preparation method of the double-bonded castor oil derivative is as follows: ricinoleic acid and methacrylic anhydride are mixed in a molar ratio of 1:3, a polymerization inhibitor (hydroquinone, the amount added is 0.3% of the mass of methacrylic anhydride) is added, the reaction is carried out at 90℃ for 3 hours, and methacrylic acid is removed by rotary evaporation to obtain the product.

[0060] The plasticizer is dioctyl adipate.

[0061] The filler is calcium carbonate.

[0062] The modified flame retardant is prepared by mixing 1 part aluminum hydroxide, 0.2 parts methacryloyloxysilane (3-methacryloyloxypropyltrimethoxysilane), and 30 parts ethanol aqueous solution (90% by mass), reacting at 75°C for 5 hours, filtering, washing, and drying to obtain aluminum hydroxide containing carbon-carbon double bonds; mixing 1 part aluminum hydroxide containing carbon-carbon double bonds, 0.3 parts vinyl polysiloxane, and 30 parts ethanol aqueous solution (90% by mass), adding 0.03 parts azobisisobutyronitrile under nitrogen protection, reacting at 70°C for 24 hours, filtering, washing, and drying to obtain the modified flame retardant.

[0063] The molecular structural formula of the vinyl polysiloxane is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH), produced by Shandong Dayi Chemical Co., Ltd., is V421-1300. It has a vinyl content of 0.0509-0.0623 mol / 100g and a viscosity of 1300±70 cps (25℃).

[0064] The stabilizer is a calcium-zinc composite stabilizer.

[0065] The lubricant is calcium stearate.

[0066] The antioxidant is antioxidant 1010.

[0067] The preparation method of the above-mentioned polyvinyl chloride flame-retardant cable sheath material includes the following steps: Modified polyvinyl chloride, plasticizer, filler, modified flame retardant, stabilizer, lubricant and antioxidant are mixed and extruded into granules to obtain polyvinyl chloride flame retardant cable sheath material. Example

[0068] This embodiment provides a polyvinyl chloride flame-retardant cable sheath material, which, by weight, includes the following raw materials: 100 parts modified polyvinyl chloride, 35 parts plasticizer, 25 parts filler, 15 parts modified flame retardant, 10 parts stabilizer, 2 parts lubricant, and 1.5 parts antioxidant.

[0069] The specific preparation method of the modified polyvinyl chloride is as follows: 100 parts of polyvinyl chloride powder are dissolved in 250 parts of solvent A (cyclohexanone), 15 parts of terminal thiol hyperbranched castor oil, 8 parts of branched polythiol B (2,3-dithio(2-mercapto)-1-propanethiol) and 25 parts of acid-binding agent (potassium carbonate) are added, and the mixture is reacted at 60°C for 12 hours under nitrogen protection. After the reaction is completed, the solvent is removed, and the mixture is washed with a 65% (v / v) methanol aqueous solution and dried to obtain the final product.

[0070] The preparation method of the terminal thiol hyperbranched castor oil is as follows: the double-bonded castor oil derivative and branched polythiol A (pentaerythritol tetra(3-mercaptopropionate)) are mixed evenly in solvent B (tetrahydrofuran, the amount added is 10 times the total mass of the double-bonded castor oil derivative and branched polythiol A (pentaerythritol tetra(3-mercaptopropionate)) at a molar ratio of 1:2. Under nitrogen protection, azobisisobutyronitrile (the amount added is 1.5% of the mass of the double-bonded castor oil derivative) is added, and the reaction is carried out at 50°C for 12 hours. After the reaction is completed, the solvent and unreacted substances are removed by rotary evaporation to obtain the final product.

[0071] The preparation method of the double-bonded castor oil derivative is as follows: ricinoleic acid and methacrylic anhydride are mixed in a molar ratio of 1:3, a polymerization inhibitor (hydroquinone, the amount added is 0.3% of the mass of methacrylic anhydride) is added, the reaction is carried out at 90℃ for 3 hours, and methacrylic acid is removed by rotary evaporation to obtain the product.

[0072] The plasticizer is dioctyl adipate.

[0073] The filler is calcium carbonate.

[0074] The modified flame retardant is prepared by mixing 1 part aluminum hydroxide, 0.2 parts methacryloyloxysilane (3-methacryloyloxypropyltrimethoxysilane), and 30 parts ethanol aqueous solution (90% by mass), reacting at 75°C for 5 hours, filtering, washing, and drying to obtain aluminum hydroxide containing carbon-carbon double bonds; mixing 1 part aluminum hydroxide containing carbon-carbon double bonds, 0.3 parts vinyl polysiloxane, and 30 parts ethanol aqueous solution (90% by mass), adding 0.03 parts azobisisobutyronitrile under nitrogen protection, reacting at 70°C for 24 hours, filtering, washing, and drying to obtain the modified flame retardant.

[0075] The molecular structural formula of the vinyl polysiloxane is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH), produced by Shandong Dayi Chemical Co., Ltd., is V421-1300. It has a vinyl content of 0.0509-0.0623 mol / 100g and a viscosity of 1300±70 cps (25℃).

[0076] The stabilizer is a calcium-zinc composite stabilizer.

[0077] The lubricant is calcium stearate.

[0078] The antioxidant is antioxidant 1010.

[0079] The preparation method of the above-mentioned polyvinyl chloride flame-retardant cable sheath material includes the following steps: Modified polyvinyl chloride, plasticizer, filler, modified flame retardant, stabilizer, lubricant and antioxidant are mixed and extruded into granules to obtain polyvinyl chloride flame retardant cable sheath material.

[0080] Comparative Example 1 The difference between this comparative example and Example 3 is that the modified polyvinyl chloride is replaced with unmodified polyvinyl chloride; all other aspects are the same.

[0081] Comparative Example 2 The difference between this comparative example and Example 3 is that the modified polyvinyl chloride was replaced with polyvinyl chloride and 15 parts of terminal thiol hyperbranched castor oil and 8 parts of branched polythiol B (2,3-dithio(2-mercapto)-1-propanethiol) were added; all other aspects were the same.

[0082] Comparative Example 3 The difference between this comparative example and Example 3 is as follows: the preparation method of the modified polyvinyl chloride is as follows: 100 parts of polyvinyl chloride powder are dissolved in 250 parts of solvent A (cyclohexanone), 15 parts of terminal thiol hyperbranched castor oil, 0 parts of branched polythiol B (2,3-dithio(2-mercapto)-1-propanethiol) and 25 parts of acid-binding agent (potassium carbonate) are added, and the mixture is reacted at 60°C for 12 hours under nitrogen protection. After the reaction is completed, the solvent is removed, and the mixture is washed with a 65% (v / v) methanol aqueous solution and dried to obtain the product; the rest are the same.

[0083] Comparative Example 4 The difference between this comparative example and Example 3 is as follows: the preparation method of the modified polyvinyl chloride is as follows: 100 parts of polyvinyl chloride powder are dissolved in 250 parts of solvent A (cyclohexanone), 15 parts of terminal mercapto hyperbranched castor oil, 8 parts of linear thiol (1,6-hexanedithiol) and 25 parts of acid-binding agent (potassium carbonate) are added, and the mixture is reacted at 60°C for 12 hours under nitrogen protection. After the reaction is completed, the solvent is removed, and the mixture is washed with a 65% methanol aqueous solution and dried to obtain the final product; the rest are the same.

[0084] Comparative Example 5 The difference between this comparative example and Example 3 is as follows: the preparation method of the modified polyvinyl chloride is as follows: 100 parts of polyvinyl chloride powder are dissolved in 250 parts of solvent A (cyclohexanone), 0 parts of terminal thiol hyperbranched castor oil, 8 parts of branched polythiol B (2,3-dithio(2-mercapto)-1-propanethiol) and 25 parts of acid-binding agent (potassium carbonate) are added, and the mixture is reacted at 60°C for 12 hours under nitrogen protection. After the reaction is completed, the solvent is removed, and the mixture is washed with a 65% (v / v) methanol aqueous solution and dried to obtain the product; the rest are the same.

[0085] Comparative Example 6 The difference between this comparative example and Example 3 is that the modified flame retardant is prepared by adding aluminum hydroxide to ethanol containing methacryloyloxysilane (3-methacryloyloxypropyltrimethoxysilane), reacting, filtering, washing, and drying to obtain the modified flame retardant; the rest are the same.

[0086] Comparative Example 7 The difference between this comparative example and Example 3 is that the molecular structure of the vinyl polysiloxane is as follows: (CH3)3SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)3, specifically V411-1000 from Shandong Dayi Chemical Co., Ltd., has a vinyl content of 0.01-0.012 mol / 100g and a viscosity of 1000±50 cps (25℃); all other properties are identical.

[0087] Comparative Example 8 The difference between this comparative example and Example 3 is that the molecular structure of the vinyl polysiloxane is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] n Si(CH3)2(CH=CH2) is V411-1000 from Shandong Dayi Chemical Co., Ltd., with a vinyl content of 0.013-0.027 mol / 100g and a viscosity of 500±25 cps (25℃); all other properties are the same.

[0088] Performance testing 1. Oxygen Index Test: The test is conducted according to the standard GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics". 2. Vertical flammability rating test: The test is conducted according to the standard GB / T 2408-2021 "Determination of flammability of plastics - Vertical method". 3. Embrittlement temperature test: The test is conducted in accordance with the standard GB / T 5470-2008 "Determination of embrittlement temperature of plastics by impact method".

[0089] The test results are shown in Table 1 below.

[0090] Table 1

[0091] Comparative experiments of Comparative Examples 1-8 and Examples 1-3 demonstrated that the modified polyvinyl chloride and modified flame retardant provided by the present invention have a good synergistic effect, not only exhibiting excellent flame retardancy but also significantly improving the low-temperature resistance of polyvinyl chloride flame-retardant cable sheath materials.

[0092] Comparative Examples 3-5 show that terminal thiol hyperbranched castor oil and branched polythiols are essential and cannot be conventionally substituted in the preparation of modified polyvinyl chloride; otherwise, the low-temperature resistance of polyvinyl chloride flame-retardant cable sheath material will decrease. Comparative Examples 6-8 show that vinyl polysiloxane is essential and cannot be routinely substituted in the preparation of modified flame retardants; otherwise, it will lead to a decrease in the flame retardancy and low-temperature resistance of polyvinyl chloride flame-retardant cable sheath materials.

[0093] Application example: A circular cable with aluminum core, PVC insulation, and PVC sheath was prepared using the PVC flame-retardant cable sheath material of Example 3. A physical diagram is shown below. Figure 1 As shown, the mechanical performance test results of the sheath are as follows: Figure 2 As shown, the results of the non-combustible experiment are as follows: Figure 3 As shown.

[0094] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A polyvinyl chloride flame-retardant cable sheath material, characterized in that, By weight, it includes the following raw materials: 100 parts modified polyvinyl chloride, 25-35 parts plasticizer, 15-25 parts filler, 8-15 parts modified flame retardant, 5-10 parts stabilizer, 1-2 parts lubricant, and 0.5-1.5 parts antioxidant. The modified polyvinyl chloride is prepared by dissolving polyvinyl chloride resin powder in solvent A, adding terminal thiol hyperbranched castor oil, branched polythiol B and acid-binding agent, reacting under nitrogen protection, and then performing post-treatment after the reaction is completed to obtain the product.

2. The polyvinyl chloride flame-retardant cable sheath material according to claim 1, characterized in that, The preparation method of the terminal thiol hyperbranched castor oil is as follows: the double-bonded castor oil derivative and the branched polythiol A are mixed evenly in solvent B, and azobisisobutyronitrile is added under nitrogen protection. After the reaction is completed, the product is obtained by post-treatment.

3. The polyvinyl chloride flame-retardant cable sheath material according to claim 2, characterized in that, The preparation method of the double-bonded castor oil derivative is as follows: ricinoleic acid and methacrylic anhydride are mixed, a polymerization inhibitor is added, the mixture is reacted, and methacrylic acid is removed by rotary evaporation to obtain the product.

4. The polyvinyl chloride flame-retardant cable sheath material according to claim 3, characterized in that, The branched polythiothiool A is selected from at least one of pentaerythritol tetra(3-mercaptopropionate) and trimethylolpropane tri(3-mercaptopropionate).

5. The polyvinyl chloride flame-retardant cable sheath material according to claim 4, characterized in that, The branched polythiol B is 2,3-dithio(2-mercapto)-1-propanethiol.

6. The polyvinyl chloride flame-retardant cable sheath material according to any one of claims 1-5, characterized in that, The modified flame retardant is obtained by reacting aluminum hydroxide containing carbon-carbon double bonds with vinyl polysiloxane.

7. The polyvinyl chloride flame-retardant cable sheath material according to claim 6, characterized in that, The modified flame retardant is prepared by mixing aluminum hydroxide, methacryloxysilane and an aqueous ethanol solution, reacting, filtering, washing and drying to obtain aluminum hydroxide containing carbon-carbon double bonds; mixing aluminum hydroxide containing carbon-carbon double bonds, vinyl polysiloxane and an aqueous ethanol solution, adding azobisisobutyronitrile under nitrogen protection, reacting, filtering, washing and drying to obtain the modified flame retardant.

8. The polyvinyl chloride flame-retardant cable sheath material according to claim 7, characterized in that, The methacryloyloxysilane is selected from at least one of 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyldimethoxysilane, methacryloyloxypropylmethyldiethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, methacryloyloxytrimethoxysilane, and methacryloyloxytriethoxysilane.

9. The polyvinyl chloride flame-retardant cable sheath material according to claim 8, characterized in that, The molecular structural formula of the vinyl polysiloxane is as follows: (CH2=CH)(CH3)2SiO[(CH3)2SiO] m [(CH2=CH)(CH3)SiO] n Si(CH3)2(CH2=CH).

10. The method for preparing the polyvinyl chloride flame-retardant cable sheath material according to any one of claims 1-9, characterized in that, Includes the following steps: Modified polyvinyl chloride, plasticizer, filler, modified flame retardant, stabilizer, lubricant and antioxidant are mixed and extruded into granules to obtain polyvinyl chloride flame retardant cable sheath material.

Images