A high-temperature resistant and flame-retardant CPVC power cable protection pipe and its preparation method

Abstract

This invention discloses a high-temperature resistant and flame-retardant CPVC power cable protection pipe and its preparation method, relating to the field of cable protection pipe technology. The high-temperature resistant and flame-retardant CPVC power cable protection pipe of this invention comprises at least the following raw materials in parts by weight: 100 parts chlorinated polyvinyl chloride; 15-25 parts high-impact MCS resin; 8-12 parts poly(1,2-propanediol adipate); 12-20 parts sepiolite-methyl methacrylate-butyl acrylate composite; 8-15 parts aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite; 3-6 parts rare earth composite heat stabilizer; 2-4 parts processing aid; 0.5-1.5 parts antioxidant; and 1-2 parts lubricant. The high-temperature resistant and flame-retardant CPVC power cable protection pipe prepared by this invention has high heat resistance, high flame retardancy, and high impact resistance, exhibiting excellent comprehensive performance, high safety and reliability, and long service life.

Description

Technical Field

[0001] This invention relates to the field of cable protection pipe technology, specifically to a high-temperature resistant and flame-retardant CPVC power cable protection pipe and its preparation method. Background Technology

[0002] With industrial development and accelerated urbanization, the advantages of power cables in power transmission have become increasingly prominent. Compared to overhead lines, power cables are typically installed underground or in other concealed locations, making them less susceptible to damage from external forces, thus improving power supply security and reducing land occupation. In engineering construction, the selection of cable protection pipes is a key factor in ensuring the safety of power transmission. First, cable protection pipes possess sufficient mechanical strength to prevent cable damage. Furthermore, cable protection pipes are primarily installed at intersections of communication cables and power lines to prevent short circuits caused by power line breaks, protecting cables, switches, circuit boards, and even the entire device from damage.

[0003] In recent years, modified chlorinated polyvinyl chloride (CPVC) power cable protection pipes have been widely used in urban and rural power grid construction and renovation due to their advantages such as high strength, corrosion resistance, heat resistance, lightweight, non-toxicity, odorlessness, environmental friendliness, and compliance with environmental protection requirements. However, with the increasing demands for safety and reliability in power systems, especially in harsh environments such as high temperatures and flammable / explosive conditions, traditional CPVC protection pipes have gradually revealed their performance shortcomings. The long-term operating temperature of ordinary CPVC pipes is typically below 93℃, and they are prone to thermal deformation under cable overload or high-temperature conditions, leading to structural instability and loss of protection for the internal cables. Although CPVC itself has a certain degree of flame retardancy, its flame retardancy rating and smoke suppression performance are insufficient to meet higher safety standards when dealing with high-intensity fires. Furthermore, the inherent brittleness of CPVC material, especially at low temperatures, results in poor impact resistance, making it susceptible to damage from external impacts during transportation, installation, and use. To improve the performance of CPVC, modification research is being conducted to enhance its heat resistance, impact resistance, and processing properties. This is of great significance for promoting the high-performance development of CPVC power cable protection pipes. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature resistant and flame-retardant CPVC power cable protection pipe and its preparation method, thereby solving the following technical problems:

[0005] Existing CPVC power cable protection pipes suffer from problems such as short service life, insufficient heat resistance, and poor impact resistance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high-temperature resistant and flame-retardant CPVC power cable protection pipe, comprising at least the following raw materials by weight:

[0008] 100 parts of chlorinated polyvinyl chloride; 15-25 parts of high-impact MCS resin; 8-12 parts of poly(1,2-propanediol adipate); 12-20 parts of sepiolite-methyl methacrylate-butyl acrylate composite; 8-15 parts of aluminum-titanium composite coupling agent modified magnesium-aluminum-lanthanum hydrotalcite; 3-6 parts of rare earth composite heat stabilizer; 2-4 parts of processing aid; 0.5-1.5 parts of antioxidant; 1-2 parts of lubricant.

[0009] As a further embodiment of the present invention: the high-impact MCS resin is obtained by polymerizing 50-60 parts by weight of styrene, 15-20 parts by weight of methyl methacrylate, 3-5 parts by weight of polyolefin elastomer and 20-22 parts by weight of chlorinated polyethylene.

[0010] As a further aspect of the present invention, the preparation method of the sepiolite-methyl methacrylate-butyl acrylate composite includes the following steps:

[0011] Deionized water, ethanol, and aluminate coupling agent were mixed and stirred. After heating, sepiolite was added. Under nitrogen protection, the mixture was stirred, and then butyl acrylate and azobisisobutyronitrile were added to react. Methyl methacrylate and azobisisobutyronitrile were then added to continue the reaction. After purification and drying, modified sepiolite was obtained.

[0012] As a further aspect of the present invention: the mass ratio of the aluminate coupling agent, the sepiolite, the butyl acrylate, the methyl methacrylate, and the azobisisobutyronitrile is 4-6:50-60:11-12:11-12:0.4-1.

[0013] According to the above-mentioned high-temperature resistant and flame-retardant CPVC power cable protection pipe, the preparation method of the aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite includes the following steps:

[0014] Sodium bicarbonate solution and sodium hydroxide solution were added dropwise to a mixed solution of magnesium nitrate, aluminum nitrate and lanthanum nitrate to carry out a coprecipitation reaction, followed by a hydrothermal reaction. After the reaction, the solution was cooled, filtered, washed, dried and ground to obtain magnesium aluminum lanthanum hydrotalcite.

[0015] The magnesium aluminum lanthanum hydrotalcite was dispersed in deionized water, and an ethanol solution of aluminum-titanium composite coupling agent was added. After stirring, the mixture was filtered, washed, and dried to obtain aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite.

[0016] As a further aspect of the present invention: the molar ratio of magnesium ions, aluminum ions and lanthanum ions in the mixed solution is 2.5-3.5:1:0.1-0.3.

[0017] As a further aspect of the present invention: the mass ratio of the aluminum-titanium composite coupling agent to the magnesium-aluminum-lanthanum hydrotalcite is 0.5-1.5:100.

[0018] As a further aspect of the present invention: the processing aid is an acrylate processing aid, the antioxidant is at least one of a phosphite antioxidant and a hindered phenolic antioxidant, and the lubricant is one or a mixture of several of polyethylene wax, oxidized polyethylene wax, or calcium stearate.

[0019] A method for preparing a high-temperature resistant and flame-retardant CPVC power cable protection pipe as described in any one of the above claims, comprising at least the following preparation steps:

[0020] Chlorinated polyvinyl chloride, poly(1,2-propanediol adipate), rare earth composite heat stabilizer, antioxidant and lubricant are added to a high-speed mixer for premixing to obtain a premixed material.

[0021] High-impact MCS resin, sepiolite-methyl methacrylate-butyl acrylate composite, aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite and processing aids are added to the premix and mixed to obtain a mixture.

[0022] The mixture is fed into a twin-screw extruder, and after melting, plasticizing, extrusion, sizing, cooling and traction, a high-temperature resistant and flame-retardant CPVC power cable protection pipe is obtained.

[0023] The beneficial effects of this invention are:

[0024] The high-temperature resistant and flame-retardant CPVC power cable protection pipe provided by this invention uses chlorinated polyvinyl chloride as the base resin. By adding high-impact MCS resin as a toughening agent, the impact resistance of the CPVC power cable protection pipe is significantly improved. The environmentally friendly plasticizer poly(1,2-propanediol adipate) is selected as the plasticizer to ensure the long service life and environmental friendliness of the product. It can weaken the intermolecular forces of CPVC and improve the processing fluidity. Acrylic ester processing aids can effectively promote the melting and plasticizing of CPVC and reduce the melt viscosity. The two, together with the lubricant, significantly widen the processing window of CPVC, reduce extrusion energy consumption, and make the pipe surface smooth and flat, without scorch spots and silver streaks. This invention also adds sepiolite-methyl methacrylate-butyl acrylate composite, aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite and rare earth composite heat stabilizer as composite flame retardant and heat stabilizer. Through the synergistic effect of each material, the problem of CPVC cable protection pipes being difficult to achieve high heat resistance, high flame retardancy and high impact resistance is solved. The prepared CPVC power cable protection pipe has excellent comprehensive performance, high safety and reliability and long service life.

[0025] The high-impact MCS resin prepared in this invention uses polyolefin elastomer and chlorinated polyethylene as the core and styrene-methyl methacrylate copolymer as the shell, forming a large number of tiny elastomer particles in the CPVC matrix. Upon impact, these particles can initiate, terminate, and disperse crazing and shear bands, absorbing a large amount of impact energy and increasing the notched impact strength of the material. This allows the prepared power cable protective sheath to withstand greater external mechanical forces, such as impacts during installation and pressure from crustal subsidence, thereby extending service life and improving reliability. Simultaneously, the methyl methacrylate units in the MCS resin have a certain polarity similarity to CPVC, while the chlorinated polyethylene rubber component has excellent compatibility with CPVC, ensuring that the MCS resin can be uniformly dispersed in the CPVC matrix and form a strong interfacial bond with the matrix, thus ensuring the highly efficient toughening of the high-impact MCS resin.

[0026] This invention uses sepiolite as a matrix, modifies its surface with an aluminate coupling agent, and then further grafts it with methyl methacrylate and butyl acrylate to prepare an inorganic-organic hybrid graft polymer, sepiolite-methyl methacrylate-butyl acrylate composite. The grafting modification of acrylate monomers improves the dispersibility and compatibility of sepiolite in various resin materials. Because of its fibrous structure, sepiolite can effectively transfer stress and can be used as a reinforcing filler, synergistically improving the toughness, rigidity, and impact resistance of the composite material with high-impact MCS resin. Furthermore, this invention also combines sepiolite-methyl methacrylate-butyl acrylate composite with magnesium aluminum lanthanum hydrotalcite modified with aluminum-titanium composite coupling agent. The one-dimensional fibrous sepiolite can form a physical barrier during combustion, delaying heat and oxygen transfer and catalyzing char formation. When magnesium aluminum lanthanum hydrotalcite decomposes under heat, it releases water and carbon dioxide, which can cool down and dilute combustible gases. The decomposition products can react with HCl produced by the combustion of CPVC and catalyze the formation of a dense and continuous char layer. The two modified fillers form complementary physical and chemical barriers during combustion, significantly improving flame retardant efficiency and achieving environmentally friendly flame retardancy.

[0027] This invention also utilizes an aluminum-titanium composite coupling agent to modify magnesium-aluminum-lanthanum hydrotalcite. The aluminum component in the aluminum-titanium composite coupling agent provides excellent hydrophilicity, firmly binding to the hydroxyl groups on the hydrotalcite layers; the titanium component provides excellent organic affinity, forming strong chemical bonds and physical entanglement with the polymer matrix. This solves the problem of easy aggregation of nano-hydrotalcite in the matrix, achieving uniform dispersion at the nanoscale, thereby simultaneously improving the mechanical properties of the material. The synergistic effect of the aluminum-titanium composite coupling agent modifying magnesium-aluminum-lanthanum hydrotalcite and the rare earth composite heat stabilizer constructs a multi-layered thermal stability protection system. The layered structure of hydrotalcite effectively absorbs and shields heat, and the gases produced by its decomposition can dilute combustibles. Rare earth elements can efficiently capture HCl produced by CPVC degradation, inhibiting chain degradation reactions. The rare earth lanthanum in the hydrotalcite and the system elements in the composite heat stabilizer form a dual rare earth stabilization system, capturing HCl from different locations and through different mechanisms, forming a three-dimensional protective network that greatly extends the thermal stability time of the material. Detailed Implementation

[0028] 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.

[0029] Example 1: The preparation method of high-impact MCS resin includes the following steps:

[0030] 56 parts by weight of styrene, 19 parts by weight of methyl methacrylate, 35 parts by weight of toluene, 3 parts by weight of polyolefin elastomer, and 22 parts by weight of chlorinated polyethylene were sequentially added to a reactor. Nitrogen gas was introduced, and after 3 minutes, all air in the reactor was ensured to be expelled. The temperature was then raised to 100°C, and swelling was carried out for 2 hours at a stirring rate of 240 r / min. The stirring rate was then reduced to 180 r / min, and 0.1 wt% of di-tert-butyl peroxide and 0.1 wt% of tert-dodecyl mercaptan were added. The reactor temperature was raised to 130°C for reaction. When the monomer conversion rate reached about 85%, the material was discharged. The obtained polymer was cut into small particles and dispersed in aluminum foil. It was then placed in a vacuum oven for devolatilization treatment at a temperature of 200°C, a pressure of -0.1 MPa, and a time of 3 minutes to obtain high-impact MCS resin.

[0031] Example 2: The preparation method of high-impact MCS resin includes the following steps:

[0032] 56 parts by weight of styrene, 19 parts by weight of methyl methacrylate, 35 parts by weight of toluene, 5 parts by weight of polyolefin elastomer, and 20 parts by weight of chlorinated polyethylene were sequentially added to a reactor. Nitrogen gas was introduced, and after 3 minutes, all air in the reactor was ensured to be expelled. The temperature was then raised to 100°C, and swelling was carried out for 2 hours at a stirring rate of 240 r / min. The stirring rate was then reduced to 180 r / min, and 0.1 wt% of di-tert-butyl peroxide and 0.1 wt% of tert-dodecyl mercaptan were added. The reactor temperature was raised to 130°C for reaction. When the monomer conversion rate reached about 85%, the material was discharged. The obtained polymer was cut into small particles and dispersed in aluminum foil. It was then placed in a vacuum oven for devolatilization treatment at a temperature of 200°C, a pressure of -0.1 MPa, and a time of 3 minutes to obtain high-impact MCS resin.

[0033] Example 3: The preparation method of the sepiolite-methyl methacrylate-butyl acrylate complex includes the following steps:

[0034] Add 590g deionized water, 50g ethanol, and 25g aluminate coupling agent to a 2000ml reactor and stir for 10min. Heat to 60℃, add 280g of ground and dried sepiolite, stir for 30min under nitrogen protection, then add 60g butyl acrylate and 1g initiator azobisisobutyronitrile in one go, react for 1h, then add 60g methyl methacrylate and 2g initiator azobisisobutyronitrile, and continue the reaction for 3h. After the reaction is complete, purify by Soxhlet extraction with ethanol at 80℃ for 48h, and then dry at 70℃ to obtain the sepiolite-methyl methacrylate-butyl acrylate complex.

[0035] Example 4: The preparation method of magnesium aluminum lanthanum hydrotalcite modified with aluminum-titanium composite coupling agent includes the following steps:

[0036] Lanthanum oxide was dissolved in nitric acid to prepare a 1.35 mol / L lanthanum nitrate solution. 21.15 g of Mg(NO3)2˙6H2O and 9.38 g of Al(NO3)3˙9H2O were weighed and dissolved in 100 mL of deionized water. 1.84 mL of the lanthanum nitrate solution was added, and the mixture was stirred until homogeneous to prepare a metal nitrate precursor solution. Separately, 9.35 g of NaOH was dissolved in 100 mL of deionized water, and 1.18 g of NaHCO3 was added to prepare an alkaline mixed solution. The metal nitrate solution was placed in an 80℃ water bath, and alkaline solution was added dropwise at a rate of 2 mL / min using a peristaltic pump to carry out a co-precipitation reaction. After the addition was completed, the reaction was continued in the water bath for 12 h. After the reaction was completed, the solution was transferred to a high-pressure reactor for a hydrothermal reaction at 170℃ for 18 h. After the reaction was completed, the solution was filtered, washed, and dried at 80℃ for 24 h. After grinding, magnesium aluminum lanthanum hydrotalcite was obtained.

[0037] The above 10g magnesium aluminum lanthanum hydrotalcite was dispersed in 250mL of water to prepare a slurry. Separately, 0.1g of aluminum titanium composite coupling agent was added to 10mL of ethanol. After mixing the two, the mixture was stirred at 75℃ for 2.5h, filtered, washed and dried to obtain aluminum titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite.

[0038] Example 5: A method for preparing a high-temperature resistant and flame-retardant CPVC power cable protection pipe includes the following steps:

[0039] 100 parts by weight of chlorinated polyvinyl chloride (J-700), 10 parts by weight of poly(1,2-propanediol adipate) (PPA), 4 parts by weight of rare earth composite heat stabilizer (REC-209), 0.3 parts by weight of antioxidant 168, 0.2 parts by weight of 1010, 0.7 parts by weight of polyethylene wax and 0.7 parts by weight of calcium stearate are added to a high-speed mixer and mixed at 100°C for 10 minutes to obtain a premix.

[0040] 18 parts by weight of the high-impact MCS resin prepared in Example 1, 15 parts by weight of the sepiolite-methyl methacrylate-butyl acrylate composite prepared in Example 3, 10 parts by weight of the aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite prepared in Example 4, and 3 parts by weight of the acrylate-based additive (ACR-401) were added to the above premix and mixed for 8 minutes at 110°C to obtain the mixture.

[0041] The above mixture is fed into a twin-screw extruder (screw diameter 65mm, length-to-diameter ratio 40:1), and the temperature is set to 170℃ in zone 1, 180℃ in zone 2, 185℃ in zone 3, 190℃ in zone 4, and 195℃ at the die head. After melting and plasticizing, extrusion, sizing, cooling and traction, a high-temperature resistant and flame-retardant CPVC power cable protection pipe is obtained.

[0042] Example 6: A method for preparing a high-temperature resistant and flame-retardant CPVC power cable protection pipe includes the following steps:

[0043] 100 parts by weight of chlorinated polyvinyl chloride (J-700), 10 parts by weight of poly(1,2-propanediol adipate) (PPA), 4 parts by weight of rare earth composite heat stabilizer (REC-209), 0.3 parts by weight of antioxidant 168, 0.2 parts by weight of 1010, 0.7 parts by weight of polyethylene wax and 0.7 parts by weight of calcium stearate are added to a high-speed mixer and mixed at 100°C for 10 minutes to obtain a premix.

[0044] 18 parts by weight of the high-impact MCS resin prepared in Example 2, 15 parts by weight of the sepiolite-methyl methacrylate-butyl acrylate composite prepared in Example 3, 10 parts by weight of the aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite prepared in Example 4, and 3 parts by weight of the acrylate-based additive (ACR-401) were added to the above premix and mixed for 8 minutes at 110°C to obtain the mixture.

[0045] The above mixture is fed into a twin-screw extruder (screw diameter 65mm, length-to-diameter ratio 40:1), and the temperature is set to 170℃ in zone 1, 180℃ in zone 2, 185℃ in zone 3, 190℃ in zone 4, and 195℃ at the die head. After melting and plasticizing, extrusion, sizing, cooling and traction, a high-temperature resistant and flame-retardant CPVC power cable protection pipe is obtained.

[0046] Example 7: A method for preparing a high-temperature resistant and flame-retardant CPVC power cable protection pipe includes the following steps:

[0047] 100 parts by weight of chlorinated polyvinyl chloride (J-700), 9 parts by weight of poly(1,2-propanediol adipate) (PPA), 5 parts by weight of rare earth composite heat stabilizer (REC-209), 0.5 parts by weight of antioxidant 168, 0.5 parts by weight of 1010, 0.9 parts by weight of polyethylene wax and 0.9 parts by weight of calcium stearate are added to a high-speed mixer and mixed at 100°C for 10 minutes to obtain a premix.

[0048] 22 parts by weight of the high-impact MCS resin prepared in Example 1, 18 parts by weight of the sepiolite-methyl methacrylate-butyl acrylate composite prepared in Example 3, 12 parts by weight of the aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite prepared in Example 4, and 3.5 parts by weight of the acrylate additive (ACR-401) were added to the above premix and mixed at 110°C for 8 minutes to obtain the mixture.

[0049] The above mixture is fed into a twin-screw extruder (screw diameter 65mm, length-to-diameter ratio 40:1), and the temperature is set to 170℃ in zone 1, 180℃ in zone 2, 185℃ in zone 3, 190℃ in zone 4, and 195℃ at the die head. After melting and plasticizing, extrusion, sizing, cooling and traction, a high-temperature resistant and flame-retardant CPVC power cable protection pipe is obtained.

[0050] Example 8: A method for preparing a high-temperature resistant and flame-retardant CPVC power cable protection pipe includes the following steps:

[0051] 100 parts by weight of chlorinated polyvinyl chloride (J-700), 9 parts by weight of poly(1,2-propanediol adipate) (PPA), 5 parts by weight of rare earth composite heat stabilizer (REC-209), 0.5 parts by weight of antioxidant 168, 0.5 parts by weight of 1010, 0.9 parts by weight of polyethylene wax and 0.9 parts by weight of calcium stearate are added to a high-speed mixer and mixed at 100°C for 10 minutes to obtain a premix.

[0052] 22 parts by weight of the high-impact MCS resin prepared in Example 2, 18 parts by weight of the sepiolite-methyl methacrylate-butyl acrylate composite prepared in Example 3, 12 parts by weight of the aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite prepared in Example 4, and 3.5 parts by weight of the acrylate additive (ACR-401) were added to the above premix and mixed at 110°C for 8 minutes to obtain the mixture.

[0053] The above mixture is fed into a twin-screw extruder (screw diameter 65mm, length-to-diameter ratio 40:1), and the temperature is set to 170℃ in zone 1, 180℃ in zone 2, 185℃ in zone 3, 190℃ in zone 4, and 195℃ at the die head. After melting and plasticizing, extrusion, sizing, cooling and traction, a high-temperature resistant and flame-retardant CPVC power cable protection pipe is obtained.

[0054] Comparative Example 1: The preparation method of silane coupling agent modified magnesium aluminum lanthanum hydrotalcite includes the following steps:

[0055] 10g of the magnesium aluminum lanthanum hydrotalcite prepared in Example 4 was dispersed in 250mL of water to prepare a slurry. Separately, 0.1g of silane coupling agent KH550 was added to 10mL of ethanol. After mixing the two, the mixture was stirred at 50℃ for 1h, filtered, washed and dried to obtain silane coupling agent modified magnesium aluminum lanthanum hydrotalcite.

[0056] The preparation method of the MCS resin in Comparative Example 2 includes the following steps:

[0057] 56 parts by weight of styrene, 19 parts by weight of methyl methacrylate, 35 parts by weight of toluene, and 25 parts by weight of chlorinated polyethylene were sequentially added to a reactor. Nitrogen gas was introduced, and after 3 minutes, all air in the reactor was ensured to be expelled. The temperature was then raised to 100°C, and swelling was carried out for 2 hours at a stirring rate of 240 r / min. The stirring rate was then reduced to 180 r / min, and 0.1 wt% of di-tert-butyl peroxide and 0.1 wt% of tert-dodecyl mercaptan were added. The reactor temperature was raised to 130°C for reaction. When the monomer conversion rate reached about 85%, the material was discharged. The obtained polymer was cut into small particles and dispersed in aluminum foil. It was then placed in a vacuum oven for devolatilization treatment at a temperature of 200°C, a pressure of -0.1 MPa, and a time of 3 minutes to obtain MCS resin.

[0058] Compared with Example 5, Comparative Example 3 only replaced the aluminum-titanium composite coupling agent modified magnesium-aluminum-lanthanum hydrotalcite prepared in Example 4 with the silane coupling agent modified magnesium-aluminum-lanthanum hydrotalcite prepared in Comparative Example 1 by mass. The remaining components and preparation methods were completely the same as those in Example 5.

[0059] Compared with Example 5, Comparative Example 4 only replaced the high-impact MCS resin prepared in Example 1 with the MCS resin prepared in Comparative Example 2 by the same mass. The other components and preparation methods were completely the same as those in Example 5.

[0060] Compared with Example 5, Comparative Example 5 only replaced the high-impact MCS resin prepared in Example 1 with chlorinated polyethylene by the same mass as in Example 5. The remaining components and preparation methods were completely the same as in Example 5.

[0061] Compared with Example 5, Comparative Example 6 only replaced the sepiolite-methyl methacrylate-butyl acrylate composite prepared in Example 3 with sepiolite by mass. The other components and preparation methods were completely the same as those in Example 5.

[0062] Performance testing

[0063] Vicat softening (heat distortion) temperature: tested according to GB / T 1633-2000, with a heating rate of 120℃ / h and a load of 10kg; the test results are shown in Table 1;

[0064] Shore hardness: The Shore hardness of the composite material was tested using a Shore hardness tester according to GB / T 2411-2008 standard. The sample thickness was not less than 6 mm. The sample was placed at a constant temperature of 23℃ for 24 hours before the performance test was carried out. At least 5 samples were tested in each group of test samples, and the average value of the test results was taken. The test results are shown in Table 1.

[0065] Cantilever beam notched impact strength test: Five standard strips were cut from a thick plate according to ASTM D256 standard. A standard V-shaped notch with a depth of 2.5 mm was milled in the middle part of one side of each strip. After placing the processed strips at 23℃ for 24 hours, the impact strength was tested on a cantilever beam impact testing machine. At least five samples were tested in each group of test samples, and the average value of the test results was taken. The test results are shown in Table 1.

[0066] Limiting Oxygen Index (LOI) Test: The test samples were tested using a Jiangning HC-2 type oxygen index analyzer in accordance with GB / T 2406-2008; the test results are shown in Table 1.

[0067] Vertical burning test: The test samples were subjected to the UL-94 vertical burning test using the Jiangning CZF-III vertical burning test machine in accordance with GB / T 2408-2008; the test results are shown in Table 1.

[0068] Congo red test paper method: According to GB / T 2917.1—2002, record the time it takes for the test sample to turn blue when heated in an oil bath at a constant temperature of 180℃; the test results are shown in Table 1;

[0069] Table 1: Statistical Table of Performance Test Data of Power Cable Protection Pipes in Examples 5-8 and Comparative Examples 3-6

[0070]

[0071] As shown in Table 1, the high-temperature resistant and flame-retardant CPVC power cable protection pipe prepared by this invention has high-temperature resistance, impact resistance, and high flame-retardant properties. In Comparative Example 3, the power cable protection pipe modified with a silane coupling agent had significantly lower impact strength, oxygen index, and thermal stability time than that of Example 5, indicating that the aluminum-titanium composite coupling agent has a better modification effect. In Comparative Example 4, no POE was added to the MCS resin, and the impact strength of the power cable protection pipe was significantly lower than that of Example 5, indicating that POE provides high elasticity and its compounding with CPE improves the impact resistance. In Comparative Example 5, pure CPE was used to replace the MCS resin, and the performance of the power cable protection pipe was inferior to that of Example 5 in all aspects, indicating that the high-impact MCS resin prepared by this invention comprehensively improves the performance of CPVC. In Comparative Example 6, ungrafted and unmodified sepiolite was used, and the performance of the power cable protection pipe decreased across the board, indicating that unmodified sepiolite is prone to agglomeration in the matrix, becoming stress defect points.

[0072] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0073] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A high-temperature resistant and flame-retardant CPVC power cable protection pipe, characterized in that, It shall include at least the following parts by weight of raw materials: 100 parts of chlorinated polyvinyl chloride; 15-25 parts of high-impact MCS resin; 8-12 parts of poly(1,2-propanediol adipate); 12-20 parts of sepiolite-methyl methacrylate-butyl acrylate composite; 8-15 parts of aluminum-titanium composite coupling agent modified magnesium-aluminum-lanthanum hydrotalcite; 3-6 parts of rare earth composite heat stabilizer; 2-4 parts of processing aid; 0.5-1.5 parts of antioxidant; 1-2 parts of lubricant. The high-impact MCS resin is obtained by polymerizing 50-60 parts by weight of styrene, 15-20 parts by weight of methyl methacrylate, 3-5 parts by weight of polyolefin elastomer, and 20-22 parts by weight of chlorinated polyethylene.

2. The high-temperature resistant and flame-retardant CPVC power cable protection pipe according to claim 1, characterized in that, The preparation method of the sepiolite-methyl methacrylate-butyl acrylate composite includes the following steps: Deionized water, ethanol, and aluminate coupling agent were mixed and stirred. After heating, sepiolite was added. Under nitrogen protection, the mixture was stirred, and then butyl acrylate and azobisisobutyronitrile were added to react. Methyl methacrylate and azobisisobutyronitrile were then added to continue the reaction. After purification and drying, modified sepiolite was obtained.

3. The high-temperature resistant and flame-retardant CPVC power cable protection pipe according to claim 2, characterized in that, The mass ratio of the aluminate coupling agent, the sepiolite, the butyl acrylate, the methyl methacrylate, and the azobisisobutyronitrile is 4-6:50-60:11-12:11-12:0.4-1.

4. The high-temperature resistant and flame-retardant CPVC power cable protection pipe according to claim 1, characterized in that, The preparation method of the aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite includes the following steps: Sodium bicarbonate solution and sodium hydroxide solution were added dropwise to a mixed solution of magnesium nitrate, aluminum nitrate and lanthanum nitrate to carry out a coprecipitation reaction, followed by a hydrothermal reaction. After the reaction, the solution was cooled, filtered, washed, dried and ground to obtain magnesium aluminum lanthanum hydrotalcite. The magnesium aluminum lanthanum hydrotalcite was dispersed in deionized water, and an ethanol solution of aluminum-titanium composite coupling agent was added. After stirring, the mixture was filtered, washed, and dried to obtain aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite.

5. The high-temperature resistant and flame-retardant CPVC power cable protection pipe according to claim 4, characterized in that, The molar ratio of magnesium ions, aluminum ions and lanthanum ions in the mixed solution is 2.5-3.5:1:0.1-0.

3.

6. The high-temperature resistant and flame-retardant CPVC power cable protection pipe according to claim 4, characterized in that, The mass ratio of the aluminum-titanium composite coupling agent to the magnesium-aluminum-lanthanum hydrotalcite is 0.5-1.5:

100.

7. The high-temperature resistant and flame-retardant CPVC power cable protection pipe according to claim 1, characterized in that, The processing aid is an acrylate processing aid, the antioxidant is at least one of a phosphite antioxidant or a hindered phenolic antioxidant, and the lubricant is one or a mixture of several of a polyethylene wax, an oxidized polyethylene wax, or calcium stearate.

8. A method for preparing a high-temperature resistant and flame-retardant CPVC power cable protection pipe as described in any one of claims 1-7, characterized in that, It includes at least the following preparation steps: Chlorinated polyvinyl chloride, poly(1,2-propanediol adipate), rare earth composite heat stabilizer, antioxidant and lubricant are added to a high-speed mixer for premixing to obtain a premixed material. High-impact MCS resin, sepiolite-methyl methacrylate-butyl acrylate composite, aluminum-titanium composite coupling agent modified magnesium aluminum lanthanum hydrotalcite and processing aids are added to the premix and mixed to obtain a mixture. The mixture is fed into a twin-screw extruder, and after melting, plasticizing, extrusion, sizing, cooling and traction, a high-temperature resistant and flame-retardant CPVC power cable protection pipe is obtained.

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