Impact-resistant HDPE corrugated pipe and preparation method thereof

Abstract

The invention discloses an anti-impact HDPE corrugated pipe and a preparation method thereof, and belongs to the technical field of corrugated pipe preparation. The anti-impact HDPE corrugated pipe is prepared from the following components in parts by weight: 70-80 parts of high-density polyethylene, 5-9 parts of polypropylene, 5-9 parts of an elastic additive, 2-5 parts of bonding resin, 1-4 parts of a compound additive, 1-2 parts of an ultraviolet light absorber and 1-2 parts of an antioxidant. The HDPE corrugated pipe prepared by the invention has excellent impact resistance, low temperature resistance and corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrugated pipe preparation, and particularly relates to an impact-resistant HDPE corrugated pipe and a preparation method thereof. Background Art

[0002] As an important pipeline material, HDPE corrugated pipes are widely used in municipal engineering such as drainage, gas supply, and water supply, as well as in fields such as agricultural irrigation and communication pipelines. However, with the continuous development of infrastructure construction and the increasing complexity of application scenarios, the performance requirements for HDPE corrugated pipes are also getting higher and higher. Traditional HDPE corrugated pipes are prone to deformation or damage when subjected to external impacts, which seriously affects their service life and safety. Especially in some areas with complex geological conditions and harsh construction environments, HDPE corrugated pipes need to withstand greater external force impacts, and the impact resistance of traditional materials often fails to meet the actual requirements. Therefore, it is urgent to improve the impact resistance of HDPE corrugated pipes.

[0003] Patent CN111087669A discloses a preparation method of an impact-resistant and highly tough corrugated pipe. In this invention, modified fossil powder is added to the raw materials for corrugated pipe preparation, and through extrusion granulation, sizing, traction, and cooling and shaping, an impact-resistant and highly tough corrugated pipe is obtained. Using talcum powder as the raw material and mixing it with sodium silicate solution, under the action of hydrochloric acid, sodium silicate reacts with hydrochloric acid to fix nano-silica particles on the surface, increasing the specific surface area of talcum powder. By adsorbing esterification products through the high specific surface area of talcum powder, the compatibility between the modified talcum powder and the polyethylene matrix is improved. When the corrugated pipe material is subjected to external forces, relative slippage is easily generated between the lamellae, improving the toughness of the corrugated board. A large amount of nano-scale silica is deposited on the surface of the modified talcum powder, improving the impact resistance of the corrugated board. However, there is still room for improvement in the impact resistance, high-temperature resistance, and corrosion resistance of the corrugated pipes prepared by this method. Summary of the Invention

[0004] The purpose of the present invention is to provide an impact-resistant HDPE corrugated pipe and a preparation method thereof, aiming to solve the technical problems of poor impact resistance, high-temperature resistance, and corrosion resistance of corrugated pipes in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides an impact-resistant HDPE corrugated pipe, which is composed of the following components in parts by weight: 70 - 80 parts of high-density polyethylene, 5 - 9 parts of polypropylene, 5 - 9 parts of elastic additive, 2 - 5 parts of bonding resin, 1 - 4 parts of composite additive, 1 - 2 parts of ultraviolet absorber, and 1 - 2 parts of antioxidant.

[0006] Preferably, the preparation method of the elastic additive includes the following steps: Q1: Under argon protection, add 2-amino-4-hydroxy-6-methylpyrimidine into a container, then add hexamethylene diisocyanate and pyridine, heat under reflux with stirring for reaction. After the reaction is completed, add n-pentane, filter by suction, wash, and dry to obtain Intermediate 1; Q2: Add 2-amino-2-methyl-1,3-propanediol into a container, then add Intermediate 1, and then add chloroform. Under nitrogen protection, heat in an oil bath for reaction. After the reaction is completed, cool, filter by suction, dissolve, centrifuge, precipitate, filter, wash, and dry to obtain Intermediate 2; In the above process, the synthesis reaction formula of Intermediate 2 is as follows:

[0007] Q3: Add oleic acid, trimethylolpropane, phthalic anhydride and neopentyl glycol into a container, then add xylene and hypophosphorous acid, raise the temperature for reaction, and continue to raise the temperature for reaction. After the reaction is completed, cool, rotary evaporate, and dry to obtain Intermediate 3; In the above process, the synthesis reaction formula of Intermediate 3 is as follows:

[0008] Q4: Add Intermediate 3 and isophorone diisocyanate into a container, then add N,N-dimethylformamide. Under nitrogen protection, raise the temperature for reaction, stir evenly, add dibutyltin dilaurate, continue the reaction, then add Intermediate 2, raise the temperature and continue the reaction. After the reaction is completed, rotary evaporate, and dry to obtain the elastic additive.

[0009] Preferably, in Q1, the dosage ratio of 2-amino-4-hydroxy-6-methylpyrimidine, hexamethylene diisocyanate, pyridine and n-pentane is (5 - 7.5) g : (50 - 75) mL : (4 - 6) mL : (15 - 20) mL, the temperature of heating under reflux with stirring for reaction is 95 - 105 °C, the reaction time is 10 - 12 h, and wash with acetone; in Q2, the dosage ratio of 2-amino-2-methyl-1,3-propanediol, Intermediate 1 and chloroform is (15 - 19.34) g : (30 - 33.4) g : (170 - 190) mL, the temperature of heating in an oil bath for reaction is 55 - 65 °C, and the reaction time is 10 - 14 h.

[0010] Preferably, in Q3, the dosage ratio of oleic acid, trimethylolpropane, phthalic anhydride, neopentyl glycol, xylene and hypophosphorous acid is (200 - 216.2) g : (91.2 - 96.4) g : (85 - 89.9) g : (10 - 14.3) g : (30 - 34.6) g : (0.6 - 1.1) g. The temperature for the first-stage reaction is raised to 150 - 155 °C, and the reaction time is 30 - 45 min. Then the temperature is further raised to 220 - 230 °C, and the reaction time is 4 - 7 h. In Q4, the dosage ratio of intermediate 3, isophorone diisocyanate, N,N-dimethylformamide, dibutyltin dilaurate and intermediate 2 is (8 - 12) g : (1.45 - 1.83) g : (30 - 40) mL : (0.01 - 0.014) mL : (0.85 - 1.02) g. The temperature for the first-stage reaction is raised to 60 - 65 °C, and the reaction time is 4 - 5 h. Then the temperature is further raised to 70 - 75 °C, and the reaction time is 1 - 2 h.

[0011] Preferably, the preparation method of the composite auxiliary agent comprises the following steps: S1: Add 9-thioxanthone and N-bromosuccinimide into a container filled with dichloromethane, then dropwise add methanesulfonic acid, stir and react at room temperature. After the reaction is completed, add sodium sulfite, extract, combine the organic phases, wash, dry, distill under reduced pressure, and recrystallize to obtain product A. Under an argon atmosphere, add diphenyl ether into tetrahydrofuran, add a n-hexane solution of n-butyllithium at a low temperature, after the dropping is completed, react at a low temperature, then react at room temperature, and then add it into a tetrahydrofuran solution containing product A for reaction. After the reaction is completed, add saturated ammonium chloride, extract, distill under vacuum, dissolve, reflux, cool, dilute, wash, reduce the pressure, and purify to obtain product B. S2: Add product B, acetamide, tris(dibenzylideneacetone)dipalladium, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene and cesium carbonate into a container. Under argon protection, add 1,4-dioxane, stir to dissolve, then heat and reflux for reaction. After the reaction is completed, cool, dilute, wash, reduce the pressure, and recrystallize to obtain product C. S3: Add product C into a mixed solution of methanol and hydrochloric acid, heat for reaction, adjust the pH, filter, and recrystallize to obtain product D. S4: Add product D, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, isoquinoline and m-cresol into a container. Under argon protection, heat and stir, then continue to heat and stir. After the stirring is completed, precipitate, filter, dissolve, purify, and dry under vacuum to obtain the composite auxiliary agent.

[0012] In the above process, the synthesis reaction formula of the composite auxiliary agent is as follows:

[0013] The results of mass spectrometry analysis of product A are as follows: m / z: 369.85 (100.0%), 367.85 (50.2%), 371.85 (47.8%), 370.85 (14.9%), 372.85 (7.7%), 368.85 (7.5%), 371.84 (4.4%), 373.84 (2.2%); the results of mass spectrometry analysis of product B are as follows: m / z: 521.91 (100.0%), 523.91 (52.2%), 519.91 (50.2%), 522.91 (27.8%), 524.91 (14.5%), 520.92 (13.7%), 523.92 (3.8%), 525.90 (2.1%), 521.92 (2.0%), 525.92 (1.7%); the results of mass spectrometry analysis of product C are as follows: m / z: 478.14 (100.0%), 479.14 (31.7%), 480.14 (6.0%), 480.13 (4.5%), 479.13 (1.5%), 481.13 (1.5%); the results of mass spectrometry analysis of product D are as follows: m / z: 394.11 (100.0%), 395.12 (27.3%), 396.11 (4.7%), 396.12 (4.0%), 395.11 (1.5%), 397.11 (1.3%).

[0014] Preferably, in S1, the dosage ratio of 9-thioxanthone, N-bromosuccinimide, dichloromethane and methanesulfonic acid is (5 - 7.2) g : (9.12 - 9.48) g : (100 - 120) mL : (3.12 - 3.54) mL, and the stirring reaction time is 10 - 12 h; the dosage ratio of diphenyl ether, n-hexane solution and product A is (1.72 - 1.98) mL : (4.12 - 4.65) mL : (2 - 2.2) g, the concentration of the n-hexane solution of n-butyllithium is 2.5 mol / L, the low-temperature environment temperature is -78~-80 °C, the low-temperature reaction time is 1 - 2 h, the room-temperature reaction time is 2 - 4 h, and the total reaction time is 10 - 12 h.

[0015] Preferably, in S2, the dosage ratio of product B, acetamide, tris(dibenzylideneacetone)dipalladium, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, cesium carbonate and 1,4-dioxane is (2 - 2.5) g : (0.45 - 0.49) g : (0.18 - 0.25) g : (0.32 - 0.45) g : (3.54 - 3.95) g : (35 - 42) mL, the heating reflux reaction temperature is 100 - 110 °C, and the reaction time is 8 - 10 h; in S3, the dosage ratio of product C, methanol and hydrochloric acid is (1.25 - 1.73) g : (8 - 12) mL : (5 - 8) mL, the heating reaction temperature is 55 - 60 °C, the reaction time is 3 - 5 h, and the pH is adjusted to 10 - 10.2.

[0016] Preferably, in S4, the dosage ratio of product D, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, isoquinoline and m-cresol is (0.45 - 0.55) g : (0.51 - 0.62) g : (0.11 - 0.16) mL : (4.8 - 5.4) mL, the heating and stirring temperature is 80 - 85 °C, the stirring time is 4 - 6 h, and the continued heating and stirring temperature is 185 - 192 °C, and the stirring time is 10 - 14 h.

[0017] Preferably, a preparation method of an impact-resistant HDPE corrugated pipe includes the following steps: Step 1: Add high-density polyethylene, polypropylene, an elastic additive, a bonding resin, a composite additive, an ultraviolet absorber and an antioxidant into a high-speed mixer, mix evenly to obtain a mixture. Step 2: Add the mixture into a twin-screw extruder, melt, mix and plasticize to obtain a uniform melt, extrude, shape, cool and cut to obtain an impact-resistant HDPE corrugated pipe.

[0018] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: 1. By adding the prepared elastic additive and composite additive to the preparation process of the HDPE corrugated pipe, the impact resistance, low-temperature resistance and chemical corrosion resistance of the HDPE corrugated pipe can be effectively improved.

[0019] 2. The elastic additive prepared in the present invention is added to the HDPE corrugated pipe, which can effectively improve its impact resistance and low-temperature resistance. The elastic additive can serve as a dispersed phase in the HDPE matrix. When the corrugated pipe is subjected to external force impact, the elastic additive can act as a stress concentration point, absorb energy through stretching and fracture, and the shear band disperses stress through plastic deformation to prevent crack propagation. At the same time, the polar groups contained can be combined with the weakly polar surface of HDPE through van der Waals forces, enhancing the interfacial bonding force and improving the impact resistance; the flexible chain segments contained in the elastic additive can still maintain high elasticity at low temperatures, delaying the embrittlement process of the corrugated pipe, and the flexible chain segments in the low-temperature environment can also move locally to absorb impact energy and inhibit brittle fracture.

[0020] 3. The composite auxiliary agent prepared in the present invention is added to the HDPE corrugated pipe, which can effectively improve its impact resistance and chemical corrosion resistance. The composite auxiliary agent can form a micron-level elastic dispersed phase in the HDPE matrix, consume energy through crazes and shear bands to enhance the impact resistance. At the same time, the carbon-fluorine bonds and low surface energy contained endow the material with excellent chemical corrosion resistance. Detailed implementation mode

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Example 1: This example discloses a preparation method of an elastic additive, including the following steps: Q1: Under argon protection, 6.25 g of 2-amino-4-hydroxy-6-methylpyrimidine is added to a container, then 62.5 mL of hexamethylene diisocyanate and 5 mL of pyridine are added, and the mixture is heated under reflux with stirring at 100 °C for 12 h. After the reaction is completed, 16.5 mL of n-pentane is added, filtered by suction, washed with acetone, and dried to obtain Intermediate 1; Q2: 17.17 g of 2-amino-2-methyl-1,3-propanediol is added to a container, then 31.7 g of Intermediate 1 is added, and then 180 mL of chloroform is added. Under nitrogen protection, the reaction is heated in an oil bath at 60 °C for 12 h. After the reaction is completed, it is cooled, filtered by suction, dissolved, centrifuged, precipitated, filtered, washed, and dried to obtain Intermediate 2; Q3: Add 208 g of oleic acid, 93.5 g of trimethylolpropane, 84.4 g of phthalic anhydride, and 12.15 g of neopentyl glycol into a container. Then add 32.3 g of xylene and 0.85 g of hypophosphorous acid. After heating the reaction at 155 °C for 30 min, continue to heat the reaction at 220 °C for 6 h. After the reaction is completed, cool, perform rotary evaporation, and dry to obtain intermediate 3; Q4: Add 10 g of intermediate 3 and 1.64 g of isophorone diisocyanate into a container. Then add 35 mL of N,N-dimethylformamide. Under nitrogen protection, heat the reaction at 60 °C for 4 h. After stirring evenly, add 0.012 mL of dibutyltin dilaurate, and continue the reaction. Then add 0.93 g of intermediate 2, and heat the reaction at 75 °C for 1 h. After the reaction is completed, perform rotary evaporation and dry to obtain the elastic additive.

[0023] This example discloses a preparation method of a composite auxiliary agent, including the following steps: S1: Add 6.6 g of 9-thioxanthone and 9.3 g of N-bromosuccinimide into a container equipped with 110 mL of dichloromethane. Then dropwise add 3.33 mL of methanesulfonic acid, and stir the reaction at room temperature for 12 h. After the reaction is completed, add sodium sulfite, extract, combine the organic phases, wash, dry, perform vacuum distillation, and recrystallize to obtain product A; Under an argon atmosphere, add 1.85 mL of diphenyl ether into 20 mL of tetrahydrofuran. Add 4.38 mL of a 2.5 mol / L n-butyllithium hexane solution at -78 °C in a low-temperature environment. After the dropping is completed, react at -78 °C for 2 h, then react at room temperature for 4 h, and then add it to a 10 mL tetrahydrofuran solution containing 2.1 g of product A, and react for 12 h. After the reaction is completed, add saturated ammonium chloride, extract, perform vacuum distillation, dissolve, reflux the reaction, cool, dilute, wash, reduce the pressure, and purify to obtain product B; S2: Add 2.25 g of product B, 0.47 g of acetamide, 0.21 g of tris(dibenzylideneacetone)dipalladium, 0.38 g of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and 3.75 g of cesium carbonate into a container. Under argon protection, add 38 mL of 1,4-dioxane, stir to dissolve, and heat the reaction under reflux at 105 °C for 10 h. After the reaction is completed, cool, dilute, wash, reduce the pressure, and recrystallize to obtain product C; S3: Add 1.49 g of product C into a mixed solution containing 10 mL of methanol and 6.5 mL of hydrochloric acid, heat the reaction at 55 °C for 4 h, then adjust the pH to 10, filter, and recrystallize to obtain product D; S4: Add 0.5 g of product D, 0.55 g of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 0.13 mL of isoquinoline, and 5.1 mL of m-cresol into a container. Under argon protection, heat and stir at 85 °C for 6 h, then continue to heat and stir at 190 °C for 12 h. After stirring, precipitate, filter, dissolve, purify, and dry under vacuum to obtain the composite auxiliary agent.

[0024] This example discloses an impact-resistant HDPE corrugated pipe, which is characterized by being composed of the following components in parts by weight: 75 parts of high-density polyethylene, 7 parts of polypropylene, 7 parts of elastic additive, 3.5 parts of bonding resin, 2.5 parts of composite auxiliary agent, 1.5 parts of ultraviolet absorber, and 1.5 parts of antioxidant.

[0025] This example discloses a preparation method of an impact-resistant HDPE corrugated pipe, including the following steps: Step 1: Add high-density polyethylene, polypropylene, elastic additive, bonding resin, composite auxiliary agent, ultraviolet absorber, and antioxidant into a high-speed mixer, mix evenly to obtain a mixture. Step 2: Add the mixture into a twin-screw extruder, melt, mix, and plasticize to obtain a uniform melt, extrude, shape, cool, and cut to obtain the impact-resistant HDPE corrugated pipe.

[0026] Example 2: This example discloses a preparation method of an elastic additive, including the following steps: Q1: Under argon protection, add 5 g of 2-amino-4-hydroxy-6-methylpyrimidine into a container, then add 75 mL of hexamethylene diisocyanate and 4 mL of pyridine, heat and stir under reflux at 100 °C for 12 h. After the reaction, add 15 mL of n-pentane, filter by suction, wash with acetone, and dry to obtain intermediate 1. Q2: Add 15 g of 2-amino-2-methyl-1,3-propanediol into a container, then add 33.4 g of intermediate 1, and then add 170 mL of chloroform. Under nitrogen protection, heat and react in an oil bath at 60 °C for 12 h. After the reaction, cool, filter by suction, dissolve, centrifuge, precipitate, filter, wash, and dry to obtain intermediate 2. Q3: Add 216.2 g of oleic acid, 91.2 g of trimethylolpropane, 85 g of phthalic anhydride, and 10 g of neopentyl glycol into a container, then add 34.6 g of xylene and 0.6 g of hypophosphorous acid. After heating and reacting at 155 °C for 30 min, continue to heat and react at 220 °C for 6 h. After the reaction, cool, rotary evaporate, and dry to obtain intermediate 3. Q4: Add 12 g of Intermediate 3 and 1.45 g of isophorone diisocyanate into a container, then add 40 mL of N,N-dimethylformamide. Under nitrogen protection, heat the reaction mixture to 60 °C and react for 4 h. After stirring evenly, add 0.014 mL of dibutyltin dilaurate, and continue the reaction. Then add 0.85 g of Intermediate 2, heat the reaction mixture to 75 °C and continue the reaction for 1 h. After the reaction is completed, perform rotary evaporation and drying to obtain an elastic additive.

[0027] This example discloses a preparation method of a composite auxiliary agent, which includes the following steps: S1: Add 5 g of 9-thioxanthone and 9.12 g of N-bromosuccinimide into a container containing 120 mL of dichloromethane, then dropwise add 3.12 mL of methanesulfonic acid, and stir the reaction at room temperature for 12 h. After the reaction is completed, add sodium sulfite, extract, combine the organic phases, wash, dry, perform vacuum distillation, and recrystallize to obtain Product A; Under an argon atmosphere, add 1.72 mL of diphenyl ether into 20 mL of tetrahydrofuran, add 4.12 mL of a 2.5 mol / L n-butyllithium hexane solution at -78 °C under a low-temperature environment. After the addition is completed, react at -78 °C for 2 h, then react at room temperature for 4 h, and then add it to a 10 mL tetrahydrofuran solution containing 2.2 g of Product A and react for 12 h. After the reaction is completed, add saturated ammonium chloride, extract, perform vacuum distillation, dissolve, reflux the reaction, cool, dilute, wash, reduce the pressure, and purify to obtain Product B; S2: Add 2.5 g of Product B, 0.45 g of acetamide, 0.18 g of tris(dibenzylideneacetone)dipalladium, 0.32 g of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and 3.54 g of cesium carbonate into a container. Under argon protection, add 35 mL of 1,4-dioxane, stir to dissolve, and heat and reflux the reaction at 105 °C for 10 h. After the reaction is completed, cool, dilute, wash, reduce the pressure, and recrystallize to obtain Product C; S3: Add 1.25 g of Product C into a mixed solution containing 12 mL of methanol and 5 mL of hydrochloric acid, heat the reaction at 55 °C for 4 h, then adjust the pH to 10, filter, and recrystallize to obtain Product D; S4: Add 0.45 g of Product D, 0.51 g of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 0.11 mL of isoquinoline, and 4.8 mL of m-cresol into a container. Under argon protection, heat and stir at 85 °C for 6 h, then continue to heat and stir at 190 °C for 12 h. After the stirring is completed, precipitate, filter, dissolve, purify, and perform vacuum drying to obtain the composite auxiliary agent.

[0028] This example discloses an impact-resistant HDPE corrugated pipe, which is characterized by being composed of the following components in parts by weight: 70 parts of high-density polyethylene, 5 parts of polypropylene, 9 parts of elastic additive, 2 parts of bonding resin, 1 part of composite auxiliary agent, 1 part of ultraviolet absorber, and 1 part of antioxidant.

[0029] This embodiment discloses a preparation method of an impact-resistant HDPE corrugated pipe, comprising the following steps: Step 1: Add high-density polyethylene, polypropylene, an elastic additive, a bonding resin, a composite auxiliary agent, an ultraviolet absorber, and an antioxidant into a high-speed mixer, mix evenly to obtain a mixed material; Step 2: Add the mixed material into a twin-screw extruder, melt, mix, and plasticize it to obtain a uniform melt, extrude, shape, cool, and cut to obtain the impact-resistant HDPE corrugated pipe.

[0030] Example 3: This embodiment discloses a preparation method of an elastic additive, comprising the following steps: Q1: Under argon protection, add 7.5 g of 2-amino-4-hydroxy-6-methylpyrimidine into a container, then add 50 mL of hexamethylene diisocyanate and 6 mL of pyridine, heat and stir under reflux at 100 °C for 12 h. After the reaction is completed, add 20 mL of n-pentane, perform suction filtration, wash with acetone, and dry to obtain Intermediate 1; Q2: Add 19.34 g of 2-amino-2-methyl-1,3-propanediol into a container, then add 30 g of Intermediate 1, and then add 190 mL of chloroform. Under nitrogen protection, heat and react in an oil bath at 60 °C for 12 h. After the reaction is completed, cool, perform suction filtration, dissolve, centrifuge, precipitate, filter, wash, and dry to obtain Intermediate 2; Q3: Add 200 g of oleic acid, 96.4 g of trimethylolpropane, 89.9 g of phthalic anhydride, and 14.3 g of neopentyl glycol into a container, then add 30 g of xylene and 1.1 g of hypophosphorous acid. After heating and reacting at 155 °C for 30 min, continue to heat and react at 220 °C for 6 h. After the reaction is completed, cool, perform rotary evaporation, and dry to obtain Intermediate 3; Q4: Add 8 g of Intermediate 3 and 1.83 g of isophorone diisocyanate into a container, then add 30 mL of N,N-dimethylformamide. Under nitrogen protection, heat and react at 60 °C for 4 h. After stirring evenly, add 0.01 mL of dibutyltin dilaurate, continue the reaction, then add 1.02 g of Intermediate 2, and continue to react by heating at 75 °C for 1 h. After the reaction is completed, perform rotary evaporation and dry to obtain the elastic additive.

[0031] This embodiment discloses a preparation method of a composite auxiliary agent, comprising the following steps: S1: Add 7.2 g of 9-thioxanthone and 9.48 g of N-bromosuccinimide into a container filled with 105 mL of dichloromethane. Then, dropwise add 3.54 mL of methanesulfonic acid, and stir the reaction at room temperature for 12 h. After the reaction is completed, add sodium sulfite, extract, combine the organic phases, wash, dry, distill under reduced pressure, and recrystallize to obtain product A. Under an argon atmosphere, add 1.98 mL of diphenyl ether into 20 mL of tetrahydrofuran. At a low temperature of -78 °C, add 4.65 mL of a 2.5 mol / L n-butyllithium hexane solution. After the addition is complete, react at a low temperature of -78 °C for 2 h, then react at room temperature for 4 h. Then, add it into a 10 mL tetrahydrofuran solution containing 2 g of product A and react for 12 h. After the reaction is completed, add saturated ammonium chloride, extract, distill under vacuum, dissolve, reflux the reaction, cool, dilute, wash, reduce the pressure, and purify to obtain product B; S2: Add 2 g of product B, 0.49 g of acetamide, 0.25 g of tris(dibenzylideneacetone)dipalladium, 0.45 g of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and 3.95 g of cesium carbonate into a container. Under argon protection, add 42 mL of 1,4-dioxane, stir to dissolve, and then heat and reflux the reaction at 105 °C for 10 h. After the reaction is completed, cool, dilute, wash, reduce the pressure, and recrystallize to obtain product C; S3: Add 1.73 g of product C into a mixed solution containing 8 mL of methanol and 8 mL of hydrochloric acid, heat and react at 55 °C for 4 h, then adjust the pH to 10, filter, and recrystallize to obtain product D; S4: Add 0.55 g of product D, 0.62 g of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 0.16 mL of isoquinoline, and 5.4 mL of m-cresol into a container. Under argon protection, heat and stir at 85 °C for 6 h, then continue to heat and stir at 190 °C for 12 h. After the stirring is completed, precipitate, filter, dissolve, purify, and dry under vacuum to obtain the composite additive.

[0032] This example discloses an impact-resistant HDPE corrugated pipe, which is characterized by being composed of the following components in parts by weight: 80 parts of high-density polyethylene, 9 parts of polypropylene, 5 parts of elastic additive, 5 parts of bonding resin, 4 parts of composite additive, 2 parts of ultraviolet absorber, and 2 parts of antioxidant.

[0033] This example discloses a preparation method of an impact-resistant HDPE corrugated pipe, including the following steps: Step 1: Add high-density polyethylene, polypropylene, elastic additive, bonding resin, composite additive, ultraviolet absorber, and antioxidant into a high-speed mixer, mix evenly to obtain a mixed material; Step 2: Add the mixed material into a twin-screw extruder, melt, mix, and plasticize to obtain a uniform melt, extrude, shape, cool, and cut to obtain the impact-resistant HDPE corrugated pipe.

[0034] Comparative Example 1: Compared with Example 1, in the process of preparing the impact-resistant HDPE corrugated pipe, no elastic additive was added in Comparative Example 1, and other conditions remained unchanged.

[0035] Comparative Example 2: Compared with Example 1, in the process of preparing the impact-resistant HDPE corrugated pipe, no composite auxiliary agent was added in Comparative Example 2, and other conditions remained unchanged.

[0036] Experimental Example: The properties of the impact-resistant HDPE corrugated pipes prepared in Examples 1-3 and Comparative Examples 1-2 were tested. The impact resistance of the samples was tested according to GB / T 14152-2001. The samples were placed in an environment of -35°C, and then the tensile strength of the samples was tested according to GB / T 1040.2-2022. The reduction rate of the tensile strength before and after the experiment was calculated. After the samples were soaked in a solution with a hydrochloric acid content of 10 vt% or a solution with an alkali content of 10 wt% for 0.5 h, they were inspected at room temperature to check whether there were obvious changes in appearance. The test results are shown in Table 1: Table 1

[0037] It can be seen from the test results in Table 1 that the HDPE corrugated pipes prepared in Examples 1-3 of the present invention have excellent impact resistance, low temperature resistance and chemical corrosion resistance. By comparing Comparative Example 1 with Examples 1-3, it can be seen that adding an elastic additive can effectively improve the impact resistance and low temperature resistance of the HDPE corrugated pipe; by comparing Comparative Example 2 with Examples 1-3, it can be seen that adding a composite auxiliary agent can improve the impact resistance and chemical corrosion resistance of the HDPE corrugated pipe.

[0038] As mentioned above, only the preferred specific embodiments of the present invention are described, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

[0039] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific embodiments. Obviously, according to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An impact-resistant HDPE corrugated pipe, characterized in that, It consists of the following components in parts by weight: 70 - 80 parts of high - density polyethylene, 5 - 9 parts of polypropylene, 5 - 9 parts of elastic additive, 2 - 5 parts of bonding resin, 1 - 4 parts of composite auxiliary agent, 1 - 2 parts of ultraviolet absorber, and 1 - 2 parts of antioxidant.

2. An impact-resistant HDPE corrugated pipe according to claim 1, characterized in that, The preparation method of the elastic additive includes the following steps: Q1: Under argon protection, add 2 - amino - 4 - hydroxy - 6 - methylpyrimidine into a container, then add hexamethylene diisocyanate and pyridine, heat for reflux stirring reaction. After the reaction is completed, add n - pentane, filter by suction, wash, and dry to obtain intermediate 1; Q2: Add 2 - amino - 2 - methyl - 1,3 - propanediol into a container, then add intermediate 1, and then add chloroform. Under nitrogen protection, react by oil - bath heating. After the reaction is completed, cool, filter by suction, dissolve, centrifuge, precipitate, filter, wash, and dry to obtain intermediate 2; Q3: Add oleic acid, trimethylolpropane, phthalic anhydride, and neopentyl glycol into a container, then add xylene and hypophosphorous acid, raise the temperature for reaction, and then continue to raise the temperature for reaction. After the reaction is completed, cool, rotary evaporate, and dry to obtain intermediate 3; Q4: Add intermediate 3 and isophorone diisocyanate into a container, then add N,N - dimethylformamide. Under nitrogen protection, raise the temperature for reaction, stir evenly, add dibutyltin dilaurate, continue the reaction, then add intermediate 2, raise the temperature and continue the reaction. After the reaction is completed, rotary evaporate and dry to obtain the elastic additive.

3. The impact-resistant HDPE corrugated pipe according to claim 2, wherein In Q1, the dosage ratio of 2 - amino - 4 - hydroxy - 6 - methylpyrimidine, hexamethylene diisocyanate, pyridine, and n - pentane is (5 - 7.5) g:(50 - 75) mL:(4 - 6) mL:(15 - 20) mL; in Q2, the dosage ratio of 2 - amino - 2 - methyl - 1,3 - propanediol, intermediate 1, and chloroform is (15 - 19.34) g:(30 - 33.4) g:(170 - 190) mL.

4. An impact-resistant HDPE corrugated pipe according to claim 2, characterized in that, In Q3, the dosage ratio of oleic acid, trimethylolpropane, phthalic anhydride, neopentyl glycol, xylene, and hypophosphorous acid is (200 - 216.2) g:(91.2 - 96.4) g:(85 - 89.9) g:(10 - 14.3) g:(30 - 34.6) g:(0.6 - 1.1) g; in Q4, the dosage ratio of intermediate 3, isophorone diisocyanate, N,N - dimethylformamide, dibutyltin dilaurate, and intermediate 2 is (8 - 12) g:(1.45 - 1.83) g:(30 - 40) mL:(0.01 - 0.014) mL:(0.85 - 1.02) g.

5. The impact-resistant HDPE corrugated pipe according to claim 1, wherein The preparation method of the composite auxiliary agent includes the following steps: S1: Add 9-thioxanthone and N-bromosuccinimide into a container filled with dichloromethane, then dropwise add methanesulfonic acid, stir and react at room temperature. After the reaction is completed, add sodium sulfite, extract, combine the organic phases, wash, dry, distill under reduced pressure, and recrystallize to obtain product A; Under an argon atmosphere, add diphenyl ether into tetrahydrofuran, add a n-hexane solution of n-butyllithium at a low temperature environment, after dropping is completed, react at a low temperature, then react at room temperature, and then add it into a tetrahydrofuran solution containing product A, react, after the reaction is completed, add saturated ammonium chloride, extract, distill under vacuum, dissolve, reflux and react, cool, dilute, wash, reduce the pressure, and purify to obtain product B; S2: Add product B, acetamide, tris(dibenzylideneacetone)dipalladium, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and cesium carbonate into a container, under argon protection, add 1,4-dioxane, stir to dissolve, then heat and reflux to react. After the reaction is completed, cool, dilute, wash, reduce the pressure, and recrystallize to obtain product C; S3: Add product C into a mixed solution of methanol and hydrochloric acid, heat and react, adjust the pH, filter, and recrystallize to obtain product D; S4: Add product D, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, isoquinoline, and m-cresol into a container, under argon protection, heat and stir, then continue to heat and stir. After stirring is completed, precipitate, filter, dissolve, purify, and dry under vacuum to obtain the composite auxiliary agent.

6. The impact-resistant HDPE corrugated pipe according to claim 5, characterized in that, In the above S1, the dosage ratio of 9-thioxanthone, N-bromosuccinimide, dichloromethane, and methanesulfonic acid is (5 - 7.2) g : (9.12 - 9.48) g : (100 - 120) mL : (3.12 - 3.54) mL; The dosage ratio of diphenyl ether, n-hexane solution, and product A is (1.72 - 1.98) mL : (4.12 - 4.65) mL : (2 - 2.2) g.

7. An impact-resistant HDPE corrugated pipe according to claim 5, characterized in that, In the above S2, the dosage ratio of product B, acetamide, tris(dibenzylideneacetone)dipalladium, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, cesium carbonate, and 1,4-dioxane is (2 - 2.5) g : (0.45 - 0.49) g : (0.18 - 0.25) g : (0.32 - 0.45) g : (3.54 - 3.95) g : (35 - 42) mL; In the above S3, the dosage ratio of product C, methanol, and hydrochloric acid is (1.25 - 1.73) g : (8 - 12) mL : (5 - 8) mL.

8. An impact-resistant HDPE corrugated pipe according to claim 5, characterized in that, In the above S4, the dosage ratio of product D, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, isoquinoline, and m-cresol is (0.45 - 0.55) g : (0.51 - 0.62) g : (0.11 - 0.16) mL : (4.8 - 5.4) mL.

9. The preparation method of an impact-resistant HDPE corrugated pipe according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1: Add high-density polyethylene, polypropylene, elastic additive, binder resin, composite auxiliary agent, ultraviolet absorber, and antioxidant into a high-speed mixer, mix evenly to obtain a mixed material; Step 2: Add the mixture into a twin-screw extruder, melt, mix and plasticize it to obtain a uniform melt, then extrude, shape, cool and cut it to obtain the impact-resistant HDPE corrugated pipe.

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