Flame-retardant PVC sleeve and preparation method thereof

Abstract

The application relates to the technical field of polyvinyl chloride sleeves, and discloses a flame-retardant PVC sleeve and a preparation method thereof. The flame-retardant PVC sleeve comprises an inner tube, a metal copper mesh coated on the outer side of the inner tube, and an outer tube coated on the outer sides of the metal copper mesh and the inner tube by injection molding. The raw material of the inner tube comprises the following components: 80-150 parts of polyvinyl chloride, 1-3 parts of chlorinated polyethylene, 20-40 parts of active nano calcium carbonate, 1-2 parts of paraffin, 1-2 parts of stearic acid, 1-3 parts of a flame retardant, and 1-2 parts of a calcium-zinc stabilizer. The raw material of the outer tube comprises the following components: 50-120 parts of polyvinyl chloride, 1-5 parts of activated fiber, 10-20 parts of active nano calcium carbonate, 1-2 parts of zeolite powder, 1-2 parts of magnesium oxide, 1-2 parts of paraffin, 1-2 parts of polyethylene wax, 1-2 parts of stearic acid, 1-5 parts of a flame retardant, 1-3 parts of a calcium-zinc stabilizer, and 1-2 parts of a processing aid LPA40. The application further discloses a preparation method of the flame-retardant PVC sleeve.

Description

Technical Field

[0001] This invention relates to the field of polyvinyl chloride (PVC) sleeve technology, and in particular to a flame-retardant PVC sleeve and its preparation method. Background Technology

[0002] Polyvinyl chloride (PVC) is one of the most widely used general-purpose plastics. Pipes made from PVC offer advantages such as smooth walls, low resistance, and relatively low price. PVC plastic not only possesses excellent mechanical properties but also superior electrical insulation properties, giving it a significant advantage in the casing industry.

[0003] When PVC pipes are used as cable conduits, they encase multiple cables. To ensure good support and protection, various fillers are often added to modify the PVC pipe and increase its rigidity. Currently, calcium carbonate is added as a conventional inorganic filler to enhance the mechanical properties of the conduit. However, calcium carbonate particles are irregularly shaped lumps, and when mixed with PVC resin, numerous voids are created between the particles, making them prone to breakage under external impact.

[0004] Meanwhile, cables generate heat during operation. Because ordinary PVC has poor thermal stability, it begins to decompose when heated above 90°C, and decomposes significantly above 120°C, releasing large amounts of hydrogen chloride gas during combustion. This can cause secondary disasters after a fire, severely hindering evacuation and firefighting efforts. Commonly used stabilizers include lead and chromium salts, but these contain heavy metals that cause serious environmental pollution. Calcium-zinc stabilizers are generally considered non-toxic compounds, but their thermal stabilization effect is inferior to that of lead salts.

[0005] Therefore, developing a PVC sleeve with excellent compressive strength, good thermal stability, excellent flame retardant properties, and easy promotion and application is of great research significance and application value. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a flame-retardant PVC sleeve and its preparation method.

[0007] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covers both the copper mesh and the inner tube. The inner tube raw materials, by weight, include: 80-150 parts polyvinyl chloride (PVC), 1-3 parts chlorinated polyethylene (PVC), 20-40 parts activated nano-calcium carbonate, 1-2 parts paraffin wax, 1-2 parts stearic acid, 1-3 parts flame retardant, and 1-2 parts calcium-zinc stabilizer. The outer tube raw materials, by weight, include: 50-120 parts PVC, 1-5 parts activated fiber, 10-20 parts activated nano-calcium carbonate, 1-2 parts zeolite powder, 1-2 parts magnesium oxide, 1-2 parts paraffin wax, 1-2 parts polyethylene wax, 1-2 parts stearic acid, 1-5 parts flame retardant, 1-3 parts calcium-zinc stabilizer, and 1-2 parts processing aid LPA40.

[0008] Preferably, the flame retardant is at least one of zinc borate, zinc stannate, ammonium octamolate, and ammonium polyphosphate.

[0009] Preferably, the active nano-calcium carbonate is prepared by the following steps: calcium hydroxide is added to water and stirred for 10-20 minutes, yttrium oxide is added while stirring, carbon dioxide gas is introduced into the mixture while stirring, and spray drying is performed; then it is added to dioxane, followed by polylactic acid, stirred at 80-95°C for 10-30 minutes, solvent is removed under reduced pressure, stirring is continued at 120-130°C for 5-10 minutes, cooled to room temperature, and pulverized.

[0010] Preferably, the mass ratio of calcium hydroxide, yttrium oxide, and polylactic acid is 5-10:0.01-0.1:0.1-1.

[0011] Preferably, the diameter of the activated fiber is 0.1-0.3 mm and the length is 3-5 mm.

[0012] Preferably, the activated fiber is prepared by the following steps: adding lignin to deionized water and stirring evenly, adding sodium silicate, sodium alginate and graphene oxide while stirring, stirring at 80-95℃ for 10-30 minutes, adjusting the pH of the system to 2-3, drying by rotary evaporation, and melt spinning.

[0013] Preferably, the mass ratio of lignin, sodium silicate, sodium alginate, and graphene oxide is 5-10:1-2:1-2:1-3.

[0014] Preferably, the spinning temperature is 200-220℃.

[0015] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0016] S1. Mix polyvinyl chloride and activated fiber, stir at 100-140℃ for 10-30 minutes, add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, flame retardant, calcium zinc stabilizer, and processing aid LPA40 in sequence, continue stirring for 5-15 minutes, extrude at 180-200℃, and granulate to obtain outer tube masterbatch.

[0017] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 100-140℃ for 10-30 minutes. Then add active nano calcium carbonate, paraffin wax, stearic acid, flame retardant and calcium zinc stabilizer in sequence and mix evenly. Extrude at 180-200℃ and cut into pellets to obtain inner tube masterbatch.

[0018] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0019] Beneficial effects:

[0020] This invention uses a calcium-zinc composite stabilized lubricant to replace the traditional lead salt stabilizer, and with the help of a flame retardant, the system has excellent flame retardant properties, a high oxygen index, and is suitable for large-scale application.

[0021] This invention combines graphene oxide into a lignin matrix, and the resulting activated fibers, obtained through spinning, not only exhibit good affinity with polyvinyl chloride (PVC), but also effectively improve the thermal conductivity of the outer tube while ensuring the mechanical strength of the product. Combined with the copper mesh, this allows for rapid heat transfer from the cable to the external environment, preventing heat accumulation on the inner tube in direct contact with the cable and ensuring normal cable operation. Furthermore, the high bonding strength between PVC and the activated fibers, further combined with activated nano-calcium carbonate, provides excellent support and thermal stability for the sheath, resulting in high impact resistance and superior flame retardant properties.

[0022] This invention involves adding calcium hydroxide to water to form a suspension, then adding yttrium oxide and treating it with carbon dioxide to form yttrium-doped nano-calcium carbonate particles. Polylactic acid is then bonded to the surface, significantly increasing the dispersibility and stability of the calcium carbonate while maintaining high interfacial compatibility with polyvinyl chloride materials, thus significantly improving the mechanical properties of the material. Experiments have shown that the combination of active nano-calcium carbonate and flame retardants has a significant synergistic effect, not only ensuring the impact strength of the material but also greatly enhancing the flame retardant effect and significantly suppressing smoke. Attached Figure Description

[0023] Figure 1 The image shows a comparison of the tensile strength and flexural strength of the flame-retardant PVC sleeves obtained in Example 5 and Comparative Examples 1-2.

[0024] Figure 2The image shows a comparison of the impact strength and oxygen index of the flame-retardant PVC sleeves obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0025] The present invention will be further explained below with reference to specific embodiments.

[0026] Calcium-zinc stabilizer was purchased from Dongguan Mouyu Chemical Co., Ltd., model CZ-108. Processing aid LPA40 was purchased from Shandong Ruimou Polymer Materials Co., Ltd.

[0027] Example 1

[0028] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0029] The inner tube materials include: 80 kg of polyvinyl chloride, 1 kg of chlorinated polyethylene, 20 kg of activated nano calcium carbonate, 1 kg of paraffin wax, 1 kg of stearic acid, 1 kg of zinc borate, and 1 kg of calcium-zinc stabilizer.

[0030] The outer tube materials include: 50 kg of polyvinyl chloride, 1 kg of activated fiber with a diameter of 0.1 mm and a length of 3 mm, 10 kg of activated nano calcium carbonate, 1 kg of zeolite powder, 1 kg of magnesium oxide, 1 kg of paraffin wax, 1 kg of polyethylene wax, 1 kg of stearic acid, 1 kg of zinc borate, 1 kg of calcium zinc stabilizer, and 1 kg of processing aid LPA40.

[0031] The active nano-calcium carbonate is prepared by the following steps: 5 kg of calcium hydroxide is added to 50 kg of water and stirred at 1000 r / min for 10 min. While stirring, 0.01 kg of yttrium oxide is added and carbon dioxide gas is introduced into the solution at a flow rate of 7 L / min for 25 s. The solution is then spray-dried. The solution is then added to 10 kg of dioxane and 0.1 kg of polylactic acid. The solution is stirred at 80℃ for 10 min, the solvent is removed under reduced pressure, and the solution is stirred at 120℃ for another 5 min. The solution is then cooled to room temperature and pulverized.

[0032] The activated fiber is prepared by the following steps: 5 kg of lignin is added to 20 kg of deionized water and stirred evenly. While stirring, 1 kg of sodium silicate, 1 kg of sodium alginate and 1 kg of graphene oxide are added. The mixture is stirred at 80℃ for 10 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the fiber is melt-spun at a temperature of 200℃.

[0033] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0034] S1. Add polyvinyl chloride and activated fiber to a mixer and stir at 100℃ for 10 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, zinc borate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 5 minutes and extrude at 180℃ to obtain outer tube masterbatch.

[0035] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 100°C for 10 minutes. Then add active nano calcium carbonate, paraffin wax, stearic acid, zinc borate, and calcium-zinc stabilizer in sequence and mix evenly. Extrude at 180°C and granulate to obtain inner tube masterbatch.

[0036] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0037] Example 2

[0038] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0039] The inner tube materials include: 150 kg of polyvinyl chloride, 3 kg of chlorinated polyethylene, 40 kg of activated nano calcium carbonate, 2 kg of paraffin wax, 2 kg of stearic acid, 3 kg of zinc stannate, and 2 kg of calcium-zinc stabilizer.

[0040] The outer tube raw materials include: 120 kg of polyvinyl chloride, 5 kg of activated fiber with a diameter of 0.3 mm and a length of 5 mm, 20 kg of activated nano calcium carbonate, 2 kg of zeolite powder, 2 kg of magnesium oxide, 2 kg of paraffin wax, 2 kg of polyethylene wax, 2 kg of stearic acid, 5 kg of zinc stannate, 3 kg of calcium-zinc stabilizer, and 2 kg of processing aid LPA40.

[0041] The active nano-calcium carbonate is prepared by the following steps: 10 kg of calcium hydroxide is added to 100 kg of water and stirred at 2000 r / min for 20 min. While stirring, 0.1 kg of yttrium oxide is added and carbon dioxide gas is introduced into the solution at a flow rate of 6 L / min for 30 s. The solution is then spray-dried. The solution is added to 20 kg of dioxane and 1 kg of polylactic acid. The solution is stirred at 95 °C for 30 min, the solvent is removed under reduced pressure, and the solution is stirred at 130 °C for another 10 min. The solution is then cooled to room temperature and pulverized.

[0042] The activated fiber is prepared by the following steps: 10 kg of lignin is added to 30 kg of deionized water and stirred evenly. While stirring, 2 kg of sodium silicate, 2 kg of sodium alginate and 3 kg of graphene oxide are added. The mixture is stirred at 95℃ for 30 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the fiber is melt-spun at a temperature of 220℃.

[0043] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0044] S1. Add polyvinyl chloride and activated fiber to a mixer and stir at 140℃ for 30 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, zinc stannate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 15 minutes and extrude at 200℃ to obtain outer tube masterbatch.

[0045] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 140℃ for 30 minutes. Then add active nano calcium carbonate, paraffin wax, stearic acid, zinc stannate and calcium zinc stabilizer in sequence and mix evenly. Extrude at 200℃ and granulate to obtain inner tube masterbatch.

[0046] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0047] Example 3

[0048] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0049] The inner tube materials include: 100 kg of polyvinyl chloride, 2.5 kg of chlorinated polyethylene, 25 kg of activated nano calcium carbonate, 1.7 kg of paraffin wax, 1.2 kg of stearic acid, 2.5 kg of ammonium octamolate, and 1.3 kg of calcium-zinc stabilizer.

[0050] The outer tube raw materials include: 100 kg of polyvinyl chloride, 4 kg of activated fiber with a diameter of 0.15 mm and a length of 4.5 mm, 12 kg of activated nano calcium carbonate, 1.7 kg of zeolite powder, 1.2 kg of magnesium oxide, 1.7 kg of paraffin wax, 1.2 kg of polyethylene wax, 1.7 kg of stearic acid, 2 kg of ammonium polyphosphate, 2.5 kg of calcium zinc stabilizer, and 1.3 kg of processing aid LPA40.

[0051] The active nano-calcium carbonate is prepared by the following steps: 9 kg of calcium hydroxide is added to 70 kg of water and stirred at 1800 r / min for 13 min. While stirring, 0.07 kg of yttrium oxide is added, and carbon dioxide gas is introduced into the mixture at a flow rate of 10 L / min for 40 s. The mixture is then spray-dried. The solution is added to 12 kg of dioxane and 0.7 kg of polylactic acid. The mixture is stirred at 85℃ for 25 min, the solvent is removed under reduced pressure, and the mixture is stirred at 122℃ for 9 min. After cooling to room temperature, the mixture is pulverized.

[0052] The activated fiber is prepared by the following steps: 7 kg of lignin is added to 28 kg of deionized water and stirred evenly. While stirring, 1.3 kg of sodium silicate, 1.8 kg of sodium alginate and 1.5 kg of graphene oxide are added. The mixture is stirred at 90℃ for 15 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the mixture is melt-spun at 215℃.

[0053] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0054] S1. Add polyvinyl chloride and activated fiber to a mixer and stir at 110℃ for 25 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, ammonium polyphosphate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 8 minutes and extrude at 195℃ to obtain outer tube masterbatch.

[0055] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 110°C for 25 minutes. Then add activated nano calcium carbonate, paraffin wax, stearic acid, ammonium octamolate, and calcium zinc stabilizer in sequence and mix evenly. Extrude at 185°C and granulate to obtain inner tube masterbatch.

[0056] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0057] Example 4

[0058] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0059] The inner tube materials include: 130 kg of polyvinyl chloride, 1.5 kg of chlorinated polyethylene, 35 kg of activated nano calcium carbonate, 1.3 kg of paraffin wax, 1.8 kg of stearic acid, 1.5 kg of ammonium polyphosphate, and 1.7 kg of calcium-zinc stabilizer.

[0060] The outer tube raw materials include: 60 kg of polyvinyl chloride, 2 kg of activated fiber with a diameter of 0.25 mm and a length of 3.5 mm, 18 kg of activated nano calcium carbonate, 1.3 kg of zeolite powder, 1.8 kg of magnesium oxide, 1.3 kg of paraffin wax, 1.8 kg of polyethylene wax, 1.3 kg of stearic acid, 4 kg of ammonium polyphosphate, 1.5 kg of calcium zinc stabilizer, and 1.7 kg of processing aid LPA40.

[0061] The active nano-calcium carbonate is prepared by the following steps: 7 kg of calcium hydroxide is added to 90 kg of water and stirred at 1200 r / min for 17 min. While stirring, 0.03 kg of yttrium oxide is added and carbon dioxide gas is introduced into the solution at a flow rate of 5 L / min for 10 s. The solution is then spray-dried. The solution is then added to 18 kg of dioxane and 0.3 kg of polylactic acid. The solution is stirred at 90℃ for 15 min, the solvent is removed under reduced pressure, and the solution is stirred at 128℃ for another 7 min. The solution is then cooled to room temperature and pulverized.

[0062] The activated fiber is prepared by the following steps: 9 kg of lignin is added to 22 kg of deionized water and stirred evenly. While stirring, 1.7 kg of sodium silicate, 1.2 kg of sodium alginate and 2.5 kg of graphene oxide are added. The mixture is stirred at 85℃ for 25 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the mixture is melt-spun at 205℃.

[0063] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0064] S1. Add polyvinyl chloride and activated fiber to a mixer and stir at 130℃ for 15 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, ammonium polyphosphate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 12 minutes and extrude at 185℃ to obtain outer tube masterbatch.

[0065] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 130°C for 15 minutes. Then add activated nano calcium carbonate, paraffin wax, stearic acid, ammonium polyphosphate, and calcium zinc stabilizer in sequence and mix evenly. Extrude at 195°C and granulate to obtain inner tube masterbatch.

[0066] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0067] Example 5

[0068] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0069] The inner tube materials include: 120 kg of polyvinyl chloride, 2 kg of chlorinated polyethylene, 30 kg of activated nano calcium carbonate, 1.5 kg of paraffin wax, 1.5 kg of stearic acid, 2 kg of ammonium polyphosphate, and 1.5 kg of calcium-zinc stabilizer.

[0070] The outer tube raw materials include: 80 kg of polyvinyl chloride, 3 kg of activated fiber with a diameter of 0.2 mm and a length of 4 mm, 15 kg of activated nano calcium carbonate, 1.5 kg of zeolite powder, 1.5 kg of magnesium oxide, 1.5 kg of paraffin wax, 1.5 kg of polyethylene wax, 1.5 kg of stearic acid, 3 kg of zinc borate, 2 kg of calcium zinc stabilizer, and 1.5 kg of processing aid LPA40.

[0071] The active nano-calcium carbonate is prepared by the following steps: 8 kg of calcium hydroxide is added to 80 kg of water and stirred at 1500 r / min for 15 min. While stirring, 0.05 kg of yttrium oxide is added and carbon dioxide gas is introduced into the solution at a flow rate of 10 L / min for 15 s. The solution is then spray-dried. The solution is then added to 15 kg of dioxane and 0.5 kg of polylactic acid. The solution is stirred at 88℃ for 20 min, the solvent is removed under reduced pressure, and the solution is stirred at 125℃ for another 8 min. The solution is then cooled to room temperature and pulverized.

[0072] The activated fiber is prepared by the following steps: 8 kg of lignin is added to 25 kg of deionized water and stirred evenly. While stirring, 1.5 kg of sodium silicate, 1.5 kg of sodium alginate and 2 kg of graphene oxide are added. The mixture is stirred at 88℃ for 20 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the fiber is melt-spun at a temperature of 210℃.

[0073] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0074] S1. Add polyvinyl chloride and activated fiber to a mixer and stir at 150℃ for 20 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, zinc borate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 10 minutes and extrude at 190℃ to obtain outer tube masterbatch.

[0075] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 120°C for 20 minutes. Then add activated nano calcium carbonate, paraffin wax, stearic acid, ammonium polyphosphate, and calcium zinc stabilizer in sequence and mix evenly. Extrude at 190°C and granulate to obtain inner tube masterbatch.

[0076] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0077] Comparative Example 1

[0078] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0079] The inner tube materials include: 120 kg of polyvinyl chloride, 2 kg of chlorinated polyethylene, 30 kg of activated nano calcium carbonate, 1.5 kg of paraffin wax, 1.5 kg of stearic acid, 2 kg of ammonium polyphosphate, and 1.5 kg of calcium-zinc stabilizer.

[0080] The outer tube raw materials include: 80 kg of polyvinyl chloride, 2.54 kg of activated fiber with a diameter of 0.2 mm and a length of 4 mm, 0.46 kg of graphene oxide, 15 kg of activated nano calcium carbonate, 1.5 kg of zeolite powder, 1.5 kg of magnesium oxide, 1.5 kg of paraffin wax, 1.5 kg of polyethylene wax, 1.5 kg of stearic acid, 3 kg of zinc borate, 2 kg of calcium zinc stabilizer, and 1.5 kg of processing aid LPA40.

[0081] The active nano-calcium carbonate is prepared by the following steps: 8 kg of calcium hydroxide is added to 80 kg of water and stirred at 1500 r / min for 15 min. While stirring, 0.05 kg of yttrium oxide is added and carbon dioxide gas is introduced into the solution at a flow rate of 10 L / min for 15 s. The solution is then spray-dried. The solution is then added to 15 kg of dioxane and 0.5 kg of polylactic acid. The solution is stirred at 88℃ for 20 min, the solvent is removed under reduced pressure, and the solution is stirred at 125℃ for another 8 min. The solution is then cooled to room temperature and pulverized.

[0082] The activated fiber is prepared by the following steps: 8 kg of lignin is added to 25 kg of deionized water and stirred evenly. While stirring, 1.5 kg of sodium silicate and 1.5 kg of sodium alginate are added. The mixture is stirred at 88℃ for 20 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the fiber is melt-spun at a temperature of 210℃.

[0083] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0084] S1. Add polyvinyl chloride, activated fiber, and graphene oxide to a mixer and stir at 150°C for 20 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, zinc borate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 10 minutes and extrude at 190°C to obtain the outer tube masterbatch.

[0085] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 120°C for 20 minutes. Then add activated nano calcium carbonate, paraffin wax, stearic acid, ammonium polyphosphate, and calcium zinc stabilizer in sequence and mix evenly. Extrude at 190°C and granulate to obtain inner tube masterbatch.

[0086] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0087] Comparative Example 2

[0088] A flame-retardant PVC sleeve includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covered by the copper mesh and the outer tube.

[0089] The inner tube materials include: 120 kg of polyvinyl chloride, 2 kg of chlorinated polyethylene, 30 kg of activated nano calcium carbonate, 1.5 kg of paraffin wax, 1.5 kg of stearic acid, 2 kg of ammonium polyphosphate, and 1.5 kg of calcium-zinc stabilizer.

[0090] The outer tube raw materials include: 80 kg of polyvinyl chloride, 3 kg of activated fiber with a diameter of 0.2 mm and a length of 4 mm, 15 kg of activated nano calcium carbonate, 1.5 kg of zeolite powder, 1.5 kg of magnesium oxide, 1.5 kg of paraffin wax, 1.5 kg of polyethylene wax, 1.5 kg of stearic acid, 3 kg of zinc borate, 2 kg of calcium zinc stabilizer, and 1.5 kg of processing aid LPA40.

[0091] The active nano-calcium carbonate is prepared by the following steps: 8 kg of calcium hydroxide is added to 80 kg of water and stirred at 1500 r / min for 15 min. Carbon dioxide gas is introduced into the mixture while stirring, with a gas flow rate of 10 L / min and a bubbling time of 15 s. The mixture is then spray-dried. 0.5 kg of polylactic acid is added to 15 kg of dioxane and stirred at 88℃ for 20 min. The solvent is removed under reduced pressure, and the mixture is stirred at 125℃ for another 8 min. The mixture is then cooled to room temperature and pulverized.

[0092] The activated fiber is prepared by the following steps: 8 kg of lignin is added to 25 kg of deionized water and stirred evenly. While stirring, 1.5 kg of sodium silicate, 1.5 kg of sodium alginate and 2 kg of graphene oxide are added. The mixture is stirred at 88℃ for 20 min. The pH of the system is adjusted to 2-3 with hydrochloric acid. The deionized water is removed by rotary evaporation. After drying, the fiber is melt-spun at a temperature of 210℃.

[0093] The preparation method of the above-mentioned flame-retardant PVC sleeve includes the following steps:

[0094] S1. Add polyvinyl chloride and activated fiber to a mixer and stir at 150℃ for 20 minutes. Then add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, zinc borate, calcium zinc stabilizer, and processing aid LPA40 in sequence. Continue stirring for 10 minutes and extrude at 190℃ to obtain outer tube masterbatch.

[0095] S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 120°C for 20 minutes. Then add activated nano calcium carbonate, paraffin wax, stearic acid, ammonium polyphosphate, and calcium zinc stabilizer in sequence and mix evenly. Extrude at 190°C and granulate to obtain inner tube masterbatch.

[0096] S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

[0097] Samples were taken from the flame-retardant PVC sleeves obtained in Example 5 and Comparative Examples 1-2, and performance tests were conducted on each group of samples, as detailed below:

[0098] (1) The tensile strength of each group of specimens was determined with reference to GB / T 1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics";

[0099] (2) The bending strength of each group of samples was determined in accordance with GB / T 9341-2008 "Determination of Flexural Properties of Plastics";

[0100] (3) The impact strength of each group of specimens was determined with reference to GB / T 1043.1-2008 "Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact test";

[0101] (4) The oxygen index of each group of samples was determined with reference to GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test".

[0102] like Figure 1 and Figure 2As shown, the flame-retardant PVC sleeve sample obtained in Example 5 exhibited the highest tensile strength, flexural strength, impact strength, and oxygen index, which were superior to those of Comparative Examples 1-2 (P < 0.05). Furthermore, during the oxygen index measurement, it was found that the smoke emission of the flame-retardant PVC sleeve sample obtained in Example 5 was significantly less than that of Comparative Examples 1-2.

[0103] The applicant believes that the above-mentioned results are due to the fact that the present invention combines graphene oxide into a lignin matrix, and the activated fibers obtained after spinning not only have good affinity with polyvinyl chloride (PVC), but also effectively improve the thermal conductivity of the outer tube while ensuring the mechanical strength of the product. Combined with the metal copper mesh, the heat of the cable can be quickly transferred to the external environment, preventing heat from accumulating on the inner tube in direct contact with the cable, thus effectively ensuring the normal operation of the cable. Simultaneously, the high bonding strength between PVC and the activated fibers, and further combined with activated nano-calcium carbonate, not only provides good support and excellent thermal conductivity for the sheath, but also results in high impact resistance and excellent flame retardant properties. This invention involves adding calcium hydroxide to water to form a suspension, then adding yttrium oxide and treating it with carbon dioxide to form yttrium-doped nano-calcium carbonate particles. Polylactic acid is then bonded to the surface, which significantly increases the dispersibility and stability of calcium carbonate and provides high interfacial compatibility with polyvinyl chloride materials, thus significantly improving the mechanical properties of the material. The combination of active nano-calcium carbonate and flame retardant has a significant synergistic effect, which not only ensures the impact strength of the material but also greatly enhances the flame retardant effect and significantly suppresses smoke.

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A flame-retardant PVC sleeve, characterized in that, Includes: an inner tube, a copper mesh covering the outside of the inner tube, and an outer tube that is injection molded and covers both the copper mesh and the inner tube. The raw materials for the inner tube, by weight, include: 80-150 parts of polyvinyl chloride, 1-3 parts of chlorinated polyethylene, 20-40 parts of activated nano calcium carbonate, 1-2 parts of paraffin wax, 1-2 parts of stearic acid, 1-3 parts of flame retardant, and 1-2 parts of calcium-zinc stabilizer. The outer tube raw materials, by weight, include: 50-120 parts polyvinyl chloride, 1-5 parts activated fiber, 10-20 parts activated nano calcium carbonate, 1-2 parts zeolite powder, 1-2 parts magnesium oxide, 1-2 parts paraffin wax, 1-2 parts polyethylene wax, 1-2 parts stearic acid, 1-5 parts flame retardant, 1-3 parts calcium zinc stabilizer, and 1-2 parts processing aid LPA40. Activated nano-calcium carbonate is prepared by the following steps: calcium hydroxide is added to water and stirred for 10-20 minutes. Yttrium oxide is added while stirring, and carbon dioxide gas is passed through the mixture while stirring. The mixture is then spray-dried. Calcium hydroxide is added to dioxane, followed by polylactic acid. The mixture is stirred at 80-95°C for 10-30 minutes, the solvent is removed under reduced pressure, and the mixture is stirred at 120-130°C for 5-10 minutes. The mixture is then cooled to room temperature and pulverized. The activated fiber is prepared by the following steps: lignin is added to deionized water and stirred evenly. Sodium silicate, sodium alginate and graphene oxide are added to the mixture while stirring. The mixture is stirred at 80-95℃ for 10-30 minutes. The pH of the system is adjusted to 2-3. The mixture is then dried by rotary evaporation and melt-spun.

2. The flame-retardant PVC sleeve according to claim 1, characterized in that, The flame retardant is at least one of zinc borate, zinc stannate, ammonium octamolate, and ammonium polyphosphate.

3. The flame-retardant PVC sleeve according to claim 1, characterized in that, The mass ratio of calcium hydroxide, yttrium oxide, and polylactic acid is 5-10:0.01-0.1:0.1-1.

4. The flame-retardant PVC sleeve according to claim 1, characterized in that, The activated fibers have a diameter of 0.1-0.3 mm and a length of 3-5 mm.

5. The flame-retardant PVC sleeve according to claim 1, characterized in that, The mass ratio of lignin, sodium silicate, sodium alginate, and graphene oxide is 5-10:1-2:1-2:1-3.

6. The flame-retardant PVC sleeve according to claim 1, characterized in that, The spinning temperature is 200-220℃.

7. A method for preparing a flame-retardant PVC sleeve as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix polyvinyl chloride and activated fiber, stir at 100-140℃ for 10-30 minutes, add activated nano calcium carbonate, zeolite powder, magnesium oxide, paraffin wax, polyethylene wax, stearic acid, flame retardant, calcium zinc stabilizer, and processing aid LPA40 in sequence, continue stirring for 5-15 minutes, extrude at 180-200℃, and granulate to obtain outer tube masterbatch. S2. Add polyvinyl chloride and chlorinated polyethylene to a mixer and stir at 100-140℃ for 10-30 minutes. Then add active nano calcium carbonate, paraffin wax, stearic acid, flame retardant and calcium zinc stabilizer in sequence and mix evenly. Extrude at 180-200℃ and cut into pellets to obtain inner tube masterbatch. S3. After the inner tube masterbatch is extruded, it is successively sized, pulled and cut to a fixed length to form an inner tube. A metal copper mesh is successively wrapped around the outer wall of the inner tube, and then the outer tube masterbatch is injection molded to wrap around the metal copper mesh and the outer side of the inner tube.

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