High-temperature-resistant and pressure-resistant PE pipe and preparation method thereof

Abstract

This application relates to the field of plastic pipes, and more particularly to a high-temperature resistant and pressure-resistant PE pipe and its preparation method. A high-temperature resistant and pressure-resistant PE pipe is composed of the following components in parts by weight: 75-85 parts polyethylene; 18-22 parts POE-g-MAH composite refined montmorillonite; 0.1-1 parts poly(octadecyl methacrylate) composite titanium dioxide; 0.6-1.2 parts antioxidant; and 0.5-1.5 parts nucleating agent. This application has the effect of improving the high-temperature resistance and pressure resistance of PE pipes.

Description

Technical Field

[0001] This application relates to the field of plastic pipes, and in particular to a high-temperature resistant and pressure-resistant PE pipe and its preparation method. Background Technology

[0002] PE (polyethylene) pipes are widely used in building water supply and drainage, municipal pipe networks, and industrial fluid transportation due to their advantages such as light weight, corrosion resistance, and convenient installation. With the continuous expansion of application scenarios, PE pipes often face harsh conditions such as high-temperature media transportation, underground pipe pressure, and long-term use under complex working conditions. However, because PE has a low melting point, it is prone to deformation or release of harmful substances when exposed to high temperatures for extended periods. Furthermore, PE material has relatively low hardness, making it prone to aging and brittleness. Therefore, to enhance the high-temperature resistance and compressive strength of PE pipes, inorganic fillers are generally added to modify the polyethylene. However, due to the poor compatibility between inorganic fillers and the polyethylene matrix, agglomeration is likely to occur, failing to effectively exert the reinforcing effect. Summary of the Invention

[0003] To improve the high temperature resistance and pressure resistance of PE pipes, this application provides a high temperature and pressure resistant PE pipe and its preparation method.

[0004] This application provides a high-temperature resistant and pressure-resistant PE pipe and its preparation method, which adopts the following technical solution: Firstly, the high-temperature resistant and pressure-resistant PE pipe provided in this application adopts the following technical solution: A high-temperature resistant and pressure-resistant PE pipe, the material being composed of the following components in parts by weight: 75-85 parts of polyethylene; 18-22 parts of POE-g-MAH composite refined montmorillonite; 0.1-1 parts of octadecyl polymethacrylate composite titanium dioxide; Antioxidant 0.6-1.2 parts; Nucleating agent 0.5-1.5 parts.

[0005] By adopting the above technical solution, POE-g-MAH is an ethylene-octene copolymer grafted with maleic anhydride. Refined montmorillonite has a layered nanostructure and a large specific surface area. Using refined montmorillonite as a nanofiller can enhance the impact resistance and heat distortion temperature of polyethylene, improving pipe rigidity. Because montmorillonite has hydrophilic and oleophobic properties, its compatibility with POE-g-MAH is improved. The use of refined montmorillonite further enhances the interfacial bonding force between montmorillonite and POE-g-MAH, thereby ensuring uniform dispersion of refined montmorillonite in the polyethylene system and further enhancing its reinforcing effect, thus increasing the impact strength of PE pipes. Simultaneously, POE-g-MAH also has a toughening effect, which is beneficial for improving the toughness and compressive strength of PE pipes. Furthermore, by combining it with polymethyl methacrylate (PMMAH)... The combination of ester-composite titanium dioxide further improves the strength and high-temperature resistance of polyethylene. POE-g-MAH can also reduce interfacial tension and improve the compatibility of polyoctadecyl methacrylate (POE) with PE. The blending of POE-g-MAH composite titanium dioxide and POE-g-MAH composite refined montmorillonite with PE allows for better composite of POE-g-MAH, refined montmorillonite, and titanium dioxide with polyethylene. POE-g-MAH improves the interfacial compatibility of the blend, stably achieving the synergistic effect of POE-g-MAH, refined montmorillonite, and titanium dioxide in improving the compressive strength of PE pipes. In addition, the addition of antioxidants can inhibit the oxidative degradation of pipes at high temperatures, which is also beneficial for delaying aging and extending the service life of pipes. The addition of nucleating agents can induce and improve the crystal structure of copolymers, further enhancing the impact strength and heat distortion temperature of PE pipes.

[0006] Preferably, the raw materials for preparing the POE-g-MAH composite refined montmorillonite include POE-g-MAH, silane coupling agent and refined montmorillonite, and the weight ratio of POE-g-MAH, silane coupling agent and refined montmorillonite is (4-7):(1.5-2.3):(15-20).

[0007] By adopting the above technical solution, refined montmorillonite is modified with a silane coupling agent to obtain silane coupling agent modified refined montmorillonite, thereby improving the bonding between refined montmorillonite and POE-g-MAH. This facilitates the stable realization of the composite of POE-g-MAH and refined montmorillonite, thereby improving the compatibility between refined montmorillonite and polyethylene. This allows refined montmorillonite to better improve the impact resistance and heat resistance of PE pipes, and POE-g-MAH further enhances the toughness of PE pipes, thus facilitating the stable improvement of the high temperature resistance and pressure resistance of PE pipes.

[0008] Preferably, the silane coupling agent is KH-550.

[0009] By adopting the above technical solution, KH-550 is used to modify refined montmorillonite. The amino groups in KH-550 react with the maleic anhydride in POE-g-MAH to form chemical bonds, thereby improving the connection stability between the silane coupling agent-modified refined montmorillonite and POE-g-MAH. This is beneficial for the stable modification effect of POE-g-MAH on refined montmorillonite. In addition, KH-550 can not only organically modify refined montmorillonite, changing the interlayer of montmorillonite from hydrophilic to oleophilic and reducing surface energy, but also increase the interlayer spacing of montmorillonite. Moreover, the refined montmorillonite particles are smaller, making it easier for coupling agent molecules to enter the interlayer of montmorillonite, further increasing the interlayer spacing of montmorillonite. This is beneficial for POE-g-MAH and polyethylene to enter the interlayer, further improving the reinforcing effect of refined montmorillonite, so as to further improve the high temperature resistance and pressure resistance of PE pipes.

[0010] Preferably, the raw materials for preparing the polyoctadecyl methacrylate composite titanium dioxide include titanium dioxide microspheres, titanate coupling agent and octadecyl methacrylate, and the weight ratio of the titanium dioxide microspheres, titanate coupling agent and octadecyl methacrylate is (0.5-1):(2.3-5.2):(5.7-8.3).

[0011] By employing the above technical solution, the surface of titanium dioxide microspheres is modified using a titanate coupling agent, forming an organic coating layer on the surface of the titanium dioxide microspheres. This improves the surface activity of the titanium dioxide microspheres. Furthermore, double bonds are grafted onto the surface of the titanium dioxide microspheres as initiation sites, facilitating the graft polymerization of octadecyl methacrylate with the titanium dioxide microspheres. This results in the coating of the titanium dioxide microspheres with polyoctadecyl methacrylate, improving the compatibility between the titanium dioxide microspheres and polyethylene. This facilitates the composite formation of titanium dioxide microspheres and polyethylene, and helps to stably achieve the modification effect of titanium dioxide on polyethylene. Consequently, the high-temperature resistance and pressure resistance of the modified polyethylene are further improved, leading to a further enhancement of the high-temperature resistance and pressure resistance of PE pipes.

[0012] Preferably, the titanate coupling agent is a vinyl titanate coupling agent.

[0013] By adopting the above technical solution, the titanate coupling agent forms an organic coating layer on the surface of titanium dioxide microspheres, and gives the surface of titanium dioxide microspheres carbon-carbon double bonds. Through free radical polymerization, styrene and divinylbenzene are cross-linked and polymerized with the double bonds on the surface of modified zirconium oxide. By blending and melting octadecyl methacrylate composite titanium dioxide with PE, the composite of titanium dioxide and PE is stably realized, improving the chemical stability of PE pipes and further improving the strength and high temperature resistance of PE pipes.

[0014] Preferably, the antioxidant is selected from one or two of phosphite antioxidants and phenolic antioxidants.

[0015] Preferably, the antioxidants are antioxidant 168 and antioxidant 1010, and the weight ratio of antioxidant 168 to antioxidant 1010 is (0.2-0.5):(0.5-0.7).

[0016] By adopting the above technical solution, antioxidant 168 and antioxidant 1010, as phosphite antioxidant and phenolic antioxidant combined in a certain proportion, produce a synergistic antioxidant effect on polyethylene, which is beneficial to improve the antioxidant effect, thereby further improving the antioxidant properties and stability of polyethylene and extending the service life of PE pipes.

[0017] Preferably, the nucleating agent is N,N'-dicyclohexyl-2,6-naphthalenediamide.

[0018] By adopting the above technical solution and adding N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide, polyethylene can form a β-crystalline structure, which improves the impact resistance and heat resistance of polyethylene, and further enhances the strength and high-temperature resistance of PE pipes.

[0019] Optionally, the polyethylene is medium-density polyethylene.

[0020] Secondly, this application provides a method for preparing high-temperature resistant and pressure-resistant PE pipes, using the following preparation scheme: A method for preparing high-temperature resistant and pressure-resistant PE pipe includes the following steps: S1. Weigh out polyethylene, POE-g-MAH composite refined montmorillonite, polymethyl methacrylate composite titanium dioxide, antioxidant and nucleating agent according to the weight ratio. Mix polyethylene with POE-g-MAH composite refined montmorillonite, polymethyl methacrylate composite titanium dioxide, antioxidant and nucleating agent in a high-speed mixer according to the weight ratio to obtain a premix. S2. The above premixed material is fed into a twin-screw extruder for melt extrusion via a metering feeder to prepare high-temperature resistant and pressure-resistant PE pipe.

[0021] In summary, this application includes at least one of the following beneficial technical effects: 1. This application uses refined montmorillonite as a nanofiller to enhance the impact resistance and heat distortion temperature of polyethylene, and improves the compatibility of refined montmorillonite through POE-g-MAH, enhances the interfacial bonding force between refined montmorillonite and polyethylene, and POE-g-MAH has a toughening effect, further improving the toughness of the polyethylene system and the compressive strength of the pipe. 2. This application also selects octadecyl methacrylate composite titanium dioxide to further improve the strength and high temperature resistance of polyethylene. Furthermore, the use of titanate coupling agent enables octadecyl methacrylate to be stably grafted and composited with modified titanium dioxide, thereby stably improving the high temperature resistance and compressive strength of polyethylene. Detailed Implementation

[0022] The following section provides further explanation of this application through specific experiments. All raw materials used in this application are commercially available.

[0023] The montmorillonite used is Comisell K-10 with grade C001939. POE-g-MAH uses maleic anhydride grafting rate of 3-5% from ExxonMobil, USA; The titanium dioxide microspheres used are 1µm titanium dioxide microspheres from Shanghai Yipuri Biotechnology Co., Ltd. The vinyl titanate coupling agent selected is the vinyl titanate coupling agent from Liyang Ruipu New Materials Co., Ltd.; The polyethylene used is MDPE of the Borealis brand ME6052. Example Example 1

[0024] Preparation method of POE-g-MAH composite refined montmorillonite: Montmorillonite was fed into a high-speed shear disperser and refined at 10,000 rpm. The refined montmorillonite was then separated in a cyclone dust collector to control the particle size to 10-20 μm. 2.0 kg of the refined montmorillonite was mixed with 0.23 kg of KH-550 and 7.5 kg of ethanol and stirred at 60 °C for 50 min. After the reaction, the mixture was allowed to cool naturally to room temperature and centrifuged to obtain a precipitate. The precipitate was dried to obtain silane coupling agent modified refined montmorillonite. Then, 0.7 kg of POE-g-MAH was mixed with the silane coupling agent modified refined montmorillonite to obtain a mixture with a maleic anhydride grafting rate of 5 wt%. The mixture was fed into a twin-screw extruder and melt-mixed at 190 °C to obtain a melt-mixed preform. The melt-mixed preform was extruded and granulated to obtain POE-g-MAH composite refined montmorillonite particles.

[0025] Preparation method of polyoctadecyl methacrylate composite titanium dioxide: 0.10 kg of titanium dioxide microspheres were mixed with 0.30 kg of toluene and ultrasonically dispersed for 40 min. Then, 0.52 kg of titanate coupling agent was added under magnetic stirring at 95 °C, and the mixture was refluxed for 50 min. After the reaction was completed, the precipitate was separated by centrifugation and dried to obtain titanate coupling agent modified titanium dioxide microspheres. Then, 0.83 kg of octadecyl methacrylate was mixed with titanate coupling agent modified titanium dioxide microspheres, and 0.6 kg of toluene solvent was added. The mixture was stirred under nitrogen atmosphere for 30 min, and 0.14 kg of initiator azobisisobutyronitrile was added. The mixture was reacted at 80 °C for 6 h, and then filtered, washed, and dried to obtain polyoctadecyl methacrylate composite titanium dioxide, wherein the titanate coupling agent was a vinyl titanate coupling agent.

[0026] Preparation of a high-temperature resistant and pressure-resistant PE pipe: S1. Mix 1.8 kg of POE-g-MAH composite refined montmorillonite, 0.01 kg of poly(octadecyl methacrylate) composite titanium dioxide, 7.5 kg of polyethylene, 0.06 kg of antioxidant and 0.05 kg of nucleating agent evenly in a high-speed mixer to obtain a premix; S2. The above premixed material is fed into a twin-screw extruder via a metering feeder, and the premixed material is melt-mixed at 280°C. Then, it is extruded through an extrusion die at 340°C to prepare high-temperature resistant and pressure-resistant PE pipe.

[0027] The antioxidant consists of 0.02 kg of antioxidant 168 and 0.04 kg of antioxidant 1010, and the nucleating agent is specifically 0.05 kg of N,N'-dicyclohexyl-2,6-naphthalenediamide. Example 2

[0028] The difference between this embodiment and Embodiment 1 is that the raw materials weighed are different in the process of preparing high-temperature and high-pressure resistant PE pipes.

[0029] In the process of preparing high-temperature and pressure-resistant PE pipes, 2.0 kg of POE-g-MAH composite refined montmorillonite, 0.07 kg of poly(octadecyl methacrylate) composite titanium dioxide, 8.0 kg of polyethylene, 0.09 kg of antioxidant and 0.10 kg of nucleating agent are weighed. The antioxidant consists of 0.04 kg of antioxidant 168 and 0.05 kg of antioxidant 1010, and the nucleating agent is 0.10 kg of N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide. Example 3

[0030] The difference between this embodiment and Embodiment 1 is that the raw materials weighed are different in the process of preparing high-temperature and high-pressure resistant PE pipes.

[0031] In the process of preparing high-temperature and pressure-resistant PE pipes, 2.2 kg of POE-g-MAH composite refined montmorillonite, 0.1 kg of poly(octadecyl methacrylate) composite titanium dioxide, 8.5 kg of polyethylene, 0.12 kg of antioxidant and 0.15 kg of nucleating agent are weighed. The antioxidant consists of 0.05 kg of antioxidant 168 and 0.07 kg of antioxidant 1010, and the nucleating agent is 0.15 kg of N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide. Example 4

[0032] The difference between this embodiment and Example 3 is that in the preparation of POE-g-MAH composite refined montmorillonite, the montmorillonite is fed into a high-speed shear disperser, which refines the montmorillonite at a speed of 8000 rpm. The montmorillonite is then separated in a cyclone dust collector, controlling the particle size to 10-20 μm to obtain refined montmorillonite. 1.5 kg of refined montmorillonite is mixed with 0.15 kg of KH-550 and 6.5 kg of ethanol, and stirred at 50°C for 30 min. After the reaction, it is naturally cooled to room temperature, centrifuged to obtain a precipitate, and dried to obtain silane coupling agent modified refined montmorillonite. Then, 0.4 kg... POE-g-MAH was mixed with silane coupling agent to modify and refine montmorillonite to obtain a mixture, wherein the maleic anhydride grafting rate of POE-g-MAH was 3wt%. The mixture was fed into a twin-screw extruder and melt-mixed at 180°C to obtain a melt-mixed preform. The melt-mixed preform was extruded and granulated to obtain POE-g-MAH composite refined montmorillonite particles. Example 5

[0033] The difference between this embodiment and Example 3 is that in the preparation of polyoctadecyl methacrylate composite titanium dioxide, 0.05 kg of titanium dioxide microspheres are mixed with 0.24 kg of toluene, ultrasonically dispersed for 35 min, and then 0.23 kg of titanate coupling agent is added under magnetic stirring at 90 °C. The mixture is refluxed for 45 min, and after the reaction is completed, the precipitate is separated by centrifugation. The precipitate is dried to obtain titanate coupling agent modified titanium dioxide microspheres. Then, 0.57 kg of octadecyl methacrylate is mixed with titanate coupling agent modified titanium dioxide microspheres, 0.5 kg of toluene solvent is added, and the mixture is stirred for 25 min under nitrogen atmosphere. 0.11 kg of initiator azobisisobutyronitrile is added, and the mixture is reacted at 80 °C for 5 h. After filtration, washing, and drying, polyoctadecyl methacrylate composite titanium dioxide is obtained, wherein the titanate coupling agent is a vinyl titanate coupling agent. Comparative Example

[0034] Comparative Example 1 The difference between this comparative example and Example 3 is that, in the preparation of POE-g-MAH composite refined montmorillonite, montmorillonite is fed into a high-speed shear disperser, which refines the montmorillonite at a speed of 10,000 rpm. The montmorillonite is then introduced into a cyclone dust collector for separation, and the particle size of the montmorillonite is controlled to 10-20 μm to obtain refined montmorillonite. 0.7 kg of POE-g-MAH and 2.0 kg of refined montmorillonite without silane coupling agent modification are mixed to obtain a mixture, wherein the maleic anhydride grafting rate of POE-g-MAH is 5 wt%. The mixture is fed into a twin-screw extruder and melt-mixed at 190°C to obtain a melt-mixed preform. The melt-mixed preform is extruded and granulated to obtain POE-g-MAH composite refined montmorillonite particles.

[0035] Comparative Example 2 The difference between this comparative example and Example 3 is that, in the process of preparing high-temperature and pressure-resistant PE pipes, POE-g-MAH composite refined montmorillonite is not added, but 2.2 kg of refined montmorillonite is added instead.

[0036] Comparative Example 3 The difference between this comparative example and Example 3 is that, in the process of preparing the high-temperature and pressure-resistant PE pipe, octadecyl methacrylate composite titanium dioxide is not added; instead, 0.1 kg of polymethyl methacrylate composite titanium dioxide is added. The preparation method of the polymethyl methacrylate composite titanium dioxide is as follows: 0.10 kg of titanium dioxide microspheres were mixed with 0.30 kg of toluene and ultrasonically dispersed for 40 min. Then, 0.52 kg of titanate coupling agent was added under magnetic stirring at 95 °C, and the mixture was refluxed for 50 min. After the reaction was completed, the precipitate was separated by centrifugation and dried to obtain titanate coupling agent modified titanium dioxide microspheres. Then, 0.83 kg of methyl methacrylate was mixed with titanate coupling agent modified titanium dioxide microspheres, 0.6 kg of toluene solvent was added, and the mixture was stirred under nitrogen for 30 min. Then, 0.14 kg of initiator azobisisobutyronitrile was added, and the mixture was reacted at 80 °C for 6 h. After filtration, washing, and drying, polymethyl methacrylate composite titanium dioxide was obtained, wherein the titanate coupling agent was a vinyl titanate coupling agent. Performance testing

[0037] The following tests were performed on the high-temperature resistant and pressure-resistant PE pipes prepared in the various embodiments and comparative examples of this application.

[0038] High temperature resistance test: Referring to GB / T 1633-2000 "Determination of Vicat softening temperature (VST) of thermoplastic plastics", test specimens were made of the high temperature resistant and pressure resistant PE pipes prepared in Examples 1-5 and Comparative Examples 1-3 of this application, and the Vicat softening temperature of the specimens was measured. The higher the Vicat softening temperature, the higher the softening critical temperature of the pipe, that is, the better the high temperature resistance.

[0039] Compression test: Referring to GB / T 9647-2015 "Determination of ring stiffness of thermoplastic pipes", test specimens were made of the high temperature resistant and compression resistant PE pipes prepared in Examples 1-5 and Comparative Examples 1-3 of this application, and the ring stiffness of the test specimens was measured.

[0040] High-temperature aging test: Referring to GB / T 19466.6-2009 "Differential scanning calorimetry (DSC) for plastics (Part 6): Determination of oxidation induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)", test specimens were made from the high-temperature resistant and pressure-resistant PE pipes prepared in Examples 1-5 and Comparative Examples 1-3 of this application. The specimens were heated from 50°C to 200°C in a nitrogen atmosphere at a rate of 20°C / min. After holding the temperature for 3 minutes, the gas was switched to oxygen, and the temperature was held for another 5 minutes after the point of significant exothermic change appeared. The oxidation induction time of the specimens was then measured.

[0041] Based on the data, it can be seen that the Vicat softening temperature of the high-temperature and pressure-resistant PE pipes prepared in Examples 1-3 all reached above 171℃, indicating good high-temperature resistance and high ring stiffness. The oxidation induction time at 200℃ was ≥49.7min, and the overall performance was better than that of the high-temperature and pressure-resistant PE pipes prepared in Comparative Examples 1-3. It can be seen that the materials obtained in the above examples have excellent performance and good high-temperature and pressure resistance.

[0042] Combining Example 3 and Comparative Example 1 with the data, it can be seen that the difference between Comparative Example 1 and Example 3 is that when preparing high-temperature and pressure-resistant PE pipes in Comparative Example 1, the montmorillonite was not refined and the silane coupling agent was not modified. It was found that the pipes showed varying degrees of reduction in high-temperature resistance, pressure resistance, and high-temperature aging resistance. This indicates that the refinement treatment of montmorillonite and the modification treatment with the silane coupling agent are beneficial to improving the strengthening effect of montmorillonite on PE pipes, and are beneficial to improving the compatibility of montmorillonite with POE-g-MAH and polyethylene. The refinement treatment of montmorillonite and the modification treatment with the silane coupling agent have a promoting effect on improving the impact resistance and heat resistance of PE pipes.

[0043] Combining Example 3 and Comparative Example 2 with the data, it can be seen that the difference between Comparative Example 2 and Example 3 is that Comparative Example 2 lacks POE-g-MAH composite refined montmorillonite. Instead, Comparative Example 2 includes refined montmorillonite. Lacking the modification treatment of refined montmorillonite and the addition of POE-g-MAH, it was found that the pipe's resistance to high temperature, pressure, and high-temperature aging was reduced to varying degrees, and further reduced compared to Comparative Example 1. This indicates that the silane coupling agent modification treatment and the composite of POE-g-MAH are beneficial to improving the strengthening effect of refined montmorillonite on PE pipes, and the composite of POE-g-MAH is beneficial to improving the compressive strength of PE pipes. This shows that the silane coupling agent modification treatment of refined montmorillonite and its composite with POE-g-MAH have a promoting effect on improving the heat resistance, compressive strength, and high-temperature aging resistance of PE pipes.

[0044] Combining Example 3 and Comparative Example 3 with the data, it can be seen that the difference between Comparative Example 3 and Example 3 is that Comparative Example 3 lacks polymethyl methacrylate (PMMA) composite titanium dioxide. Instead, PMMA composite titanium dioxide is added to Comparative Example 3. It was found that the pipe material's high temperature resistance, pressure resistance, and high temperature aging resistance were all reduced to varying degrees, and the reduction in ring stiffness was significant. Since PMMA has poorer compatibility with polyethylene than PMMA, using PMMA instead of PMMA in the composite with titanium dioxide reduces the compatibility of the titanium dioxide composite in polyethylene, making it easier to produce a clear phase interface. This indicates that PMMA composite titanium dioxide in the composite system with polyethylene is mainly used to improve the system's stress and heat resistance, thereby further improving the heat resistance and pressure resistance of the PE pipe.

[0045] Based on Examples 3 and 4 and the data, it can be seen that POE-g-MAH composite refined montmorillonite can effectively improve the Vicat softening temperature and ring stiffness of the system and prolong the oxidation induction time, thereby effectively improving the strength and high temperature resistance of the pipe.

[0046] Combining Examples 3 and 5 with the data, it can be seen that polyoctadecyl methacrylate composite titanium dioxide can effectively improve the Vicat softening temperature and ring stiffness of the system, thereby further improving the strength and high temperature resistance of PE pipes.

[0047] The above are all preferred embodiments of this application. These embodiments are only explanations of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-temperature resistant and pressure-resistant PE pipe, characterized in that: Composed of the following components in parts by weight: 75-85 parts of polyethylene; 18-22 parts of POE-g-MAH composite refined montmorillonite; 0.1-1 parts of octadecyl polymethacrylate composite titanium dioxide; Antioxidant 0.6-1.2 parts; Nucleating agent 0.5-1.5 parts.

2. The high-temperature resistant and pressure-resistant PE pipe according to claim 1, characterized in that: The raw materials for preparing the POE-g-MAH composite refined montmorillonite include POE-g-MAH, silane coupling agent and refined montmorillonite, and the weight ratio of POE-g-MAH, silane coupling agent and refined montmorillonite is (4-7):(1.5-2.3):(15-20).

3. The high-temperature resistant and pressure-resistant PE pipe according to claim 2, characterized in that: The silane coupling agent used is KH-550.

4. The high-temperature resistant and pressure-resistant PE pipe according to claim 1, characterized in that: The raw materials for preparing the polyoctadecyl methacrylate composite titanium dioxide include titanium dioxide microspheres, titanate coupling agent and octadecyl methacrylate, and the weight ratio of the titanium dioxide microspheres, titanate coupling agent and octadecyl methacrylate is (0.5-1):(2.3-5.2):(5.7-8.3).

5. The high-temperature resistant and pressure-resistant PE pipe according to claim 4, characterized in that: The titanate coupling agent is a vinyl titanate coupling agent.

6. The high-temperature resistant and pressure-resistant PE pipe according to claim 1, characterized in that: The antioxidant is selected from one or two of phosphite antioxidants and phenolic antioxidants.

7. The high-temperature resistant and pressure-resistant PE pipe according to claim 6, characterized in that: The antioxidants selected are antioxidant 168 and antioxidant 1010, and the weight ratio of antioxidant 168 to antioxidant 1010 is (0.2-0.5):(0.5-0.7).

8. The high-temperature resistant and pressure-resistant PE pipe according to claim 1, characterized in that: The nucleating agent is N,N'-dicyclohexyl-2,6-naphthalenediamide.

9. The high-temperature resistant and pressure-resistant PE pipe according to claim 1, characterized in that: The polyethylene is medium-density polyethylene.

10. A method for preparing high-temperature resistant and pressure-resistant PE pipe according to any one of claims 1-9, characterized in that: Includes the following steps: S1. Weigh out polyethylene, POE-g-MAH composite refined montmorillonite, polymethyl methacrylate composite titanium dioxide, antioxidant and nucleating agent according to the weight ratio. Mix polyethylene with POE-g-MAH composite refined montmorillonite, polymethyl methacrylate composite titanium dioxide, antioxidant and nucleating agent in a high-speed mixer according to the weight ratio to obtain a premix. S2. The above premixed material is fed into a twin-screw extruder for melt extrusion via a metering feeder to prepare high-temperature resistant and pressure-resistant PE pipe.