HDPE high molecular weight polyethylene square reinforced corrugated pipe

Abstract

This invention discloses a square-shaped reinforced corrugated pipe of high molecular weight polyethylene (HDPE), belonging to the field of HDPE corrugated pipe manufacturing technology. It comprises the following raw materials in parts by weight: 60 parts high-density polyethylene, 30-50 parts ultra-high molecular weight polyethylene, 10-30 parts reinforcing polyethylene fiber, 5-12 parts maleic anhydride-grafted SEBS, and 0.5-2.0 parts dynamic crosslinking agent. The preparation method includes the following steps: S1. Mixing; S2. Granulation; S3. Flat-walled pipe blank extrusion: the blended granules are extruded through a single-screw extruder and vacuum-sized to obtain a flat-walled pipe blank; S4. Square corrugation molding: the flat-walled pipe blank is preheated with infrared radiation, pneumatically molded, and gradient cooled to obtain the HDPE square-shaped reinforced corrugated pipe. The HDPE square-shaped reinforced corrugated pipe obtained by this invention has high mechanical strength and good creep resistance.

Description

Technical Field

[0001] This invention belongs to the field of HDPE corrugated pipe manufacturing technology, specifically HDPE high molecular weight polyethylene square reinforced corrugated pipe. Background Technology

[0002] High-density polyethylene (HDPE) corrugated pipes have been widely used in many fields such as municipal drainage and cable protection due to their significant advantages such as lightweight, corrosion resistance, and convenient construction. However, traditional HDPE corrugated pipes have certain limitations in terms of compressive and impact resistance. Specifically, the rigidity and creep resistance of ordinary HDPE are insufficient to meet the requirements of deep burial conditions; when conventional glass fiber or carbon fiber is used for reinforcement, their poor compatibility with HDPE can easily lead to interfacial delamination, and uneven fiber dispersion can reduce the ring stiffness of the pipe; in addition, traditionally formulated HDPE corrugated pipes are prone to brittleness at high temperatures. Although dynamic cross-linking technology can improve its heat resistance to some extent, it often comes at the cost of sacrificing processing fluidity.

[0003] Currently, to address the aforementioned issues, much research focuses on modifying or pretreating various inorganic fibers. For example, existing technology CN119264540A discloses a reinforcing masterbatch for HDPE double-wall corrugated pipes, which uses silane-modified inorganic fibers as reinforcing fibers to improve the pipe's ring stiffness and creep resistance. However, the compatibility issue between inorganic fibers and polyethylene still exists, resulting in poor durability of HDPE corrugated pipes after long-term use. Summary of the Invention

[0004] To overcome the aforementioned technical problems, this invention provides a square-shaped reinforced corrugated pipe made of high-molecular-weight polyethylene (HDPE). The HDPE square-shaped reinforced corrugated pipe produced by this invention using fiber self-reinforcement and dynamic cross-linking processes exhibits high strength and good creep resistance.

[0005] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0006] This invention discloses a square-shaped reinforced corrugated pipe made of high-molecular-weight polyethylene (HDPE), comprising the following raw materials in parts by weight: 60 parts high-density polyethylene (HDPE), 30-50 parts ultra-high molecular weight polyethylene (UHMWPE), 10-30 parts reinforcing polyethylene fiber, 5-12 parts maleic anhydride-grafted SEBS, and 0.5-2.0 parts dynamic crosslinking agent. High-density polyethylene and ultra-high molecular weight polyethylene are added as matrix components.

[0007] Preferably, the HDPE high molecular weight polyethylene square reinforced corrugated pipe comprises the following raw materials in parts by weight: 60 parts high-density polyethylene, 30-40 parts ultra-high molecular weight polyethylene, 15-25 parts reinforced polyethylene fiber, 8-10 parts maleic anhydride grafted SEBS and 0.8-1.5 parts dynamic crosslinking agent.

[0008] The method for preparing the reinforced polyethylene fiber involves immobilizing ultra-high molecular weight polyethylene fibers after swelling in a mixed solvent of decahydronaphthalene and xylene. Decahydronaphthalene is a good solvent for high molecular weight polyethylene fibers, effectively penetrating the amorphous regions of the fiber and relaxing the molecular chains. Xylene, as an auxiliary solvent, penetrates the micropores of the fiber surface more quickly and easily than decahydronaphthalene due to its smaller molecular weight. Solvent penetration relaxes the molecular chains on the fiber surface, forming an entangleable "sticky outer shell layer" that interlocks with the molecular chains of the matrix components.

[0009] In some preferred embodiments, the equivalent diameter of the ultra-high molecular weight polyethylene fiber is 15–20 μm.

[0010] In some preferred embodiments, the elastic modulus of the ultra-high molecular weight polyethylene fiber is >95 GPa.

[0011] In some preferred embodiments, the tensile strength of the ultra-high molecular weight polyethylene fiber is >3500MPa.

[0012] In some preferred embodiments, the volume ratio of decahydronaphthalene / xylene is 3 to 2:1.

[0013] In some preferred embodiments, the swelling temperature is 78–82°C, and the swelling time is 30–45 seconds.

[0014] In some preferred embodiments, the degree of swelling is controlled to be 15-20% of the fiber diameter expansion rate.

[0015] In some preferred embodiments, the immobilization involves immediately immersing the swollen ultra-high molecular weight polyethylene fibers in ethanol at -15 to -20°C for 3 to 8 seconds.

[0016] In some preferred embodiments, the residual solvent after immobilization is removed by hot air circulation.

[0017] In some preferred embodiments, the Mw of the ultra-high molecular weight polyethylene powder is ≥2.5 million.

[0018] In some preferred embodiments, the melt index (190°C, 5kg) of the high-density polyethylene is 0.1 to 0.6 g / 10min.

[0019] In some preferred embodiments, the melt index (190°C, 2.16 kg) of the maleic anhydride-grafted SEBS is 0.5–3.0 g / 10 min.

[0020] In some preferred embodiments, the grafting rate of the maleic anhydride-grafted SEBS is 1.0% to 2.0%.

[0021] Among them, maleic anhydride grafted SEBS acts as a compatibilizer and toughening agent to improve dispersibility.

[0022] In some preferred embodiments, the dynamic crosslinking agent is dicumyl peroxide (DCP, CAS No.: 80-43-3) and triallyl isocyanurate (TAIC, CAS No.: 1025-15-6); the mass ratio of dicumyl peroxide (DCP): triallyl isocyanurate (TAIC) in the dynamic crosslinking agent is 1:1.2-1.5. DCP acts as a free radical initiator, and its half-life determines the crosslinking rate; TAIC is a trifunctional crosslinking aid, and a slight excess ensures sufficient free radical capture, preventing degradation caused by unreacted DCP.

[0023] In some preferred embodiments, the raw materials for preparing the HDPE high molecular weight polyethylene square reinforced corrugated pipe further include additives; the additives are 2 to 5 parts rheology modifier, 0.5 to 2 parts UV-resistant composite agent and 0.3 to 0.7 parts lubricant; preferably, the additives are 2 to 3 parts rheology modifier, 0.7 to 1.2 parts UV-resistant composite agent and 0.3 to 0.7 parts lubricant.

[0024] In some preferred embodiments, the UV-resistant composite agent is nano-cerium oxide and a light stabilizer. Preferably, the mass ratio of the UV-resistant composite agent nano-cerium oxide to the light stabilizer is 1:2 to 3.

[0025] The light stabilizer is light stabilizer 944 (CAS No.: 70624-18-9), light stabilizer UV-292 (CAS No.: 82919-37-7), or light stabilizer 770 (CAS No.: 52829-07-9);

[0026] Furthermore, the lubricant is at least one of polyethylene wax, modified polyethylene wax, mineral oil, potassium stearate, zinc stearate, sodium stearate, and magnesium stearate; the lubricant and the hyperbranched polyester synergistically regulate the rheological properties and reduce extrusion fluctuations.

[0027] In some preferred embodiments, the rheology modifier is a hyperbranched polyester; the rheology modifier is a hydroxyl-terminated hyperbranched polyester or a carboxyl-terminated hyperbranched polyester.

[0028] In this invention, the HDPE (high molecular weight polyethylene) square reinforced corrugated pipe is prepared by the following steps:

[0029] S1. Mixing: The dynamic crosslinking agent is dissolved in acetone and then premixed with high-density polyethylene and ultra-high molecular weight polyethylene through atomized spraying. Then, maleic anhydride grafted SEBS, reinforced polyethylene fibers and additives are added to obtain the mixture.

[0030] S2. Granulation: The mixture is extruded and granulated using a twin-screw granulator;

[0031] S3. Flat-walled tube blank extrusion: The blended granules are extruded through a single screw extruder and vacuum sizing to obtain a flat-walled tube blank;

[0032] S4. Square Corrugated Forming: HDPE square reinforced corrugated pipe is obtained by infrared preheating, air pressure forming and gradient cooling of flat wall tube blank.

[0033] In S2, the temperatures of each zone of the twin-screw extruder are as follows: feeding zone 160±3℃—melting zone 190±2℃—mixing zone 205±2℃—fiber inlet zone 180±2℃—homogenization zone 195±3℃—die zone 200±2℃.

[0034] In S3, the extrusion speed of the single screw extruder is 25-30 rpm;

[0035] In S3, the pump outlet pressure of the single-screw extruder is ≥8MPa;

[0036] In S3, the vacuum degree of the vacuum calibrator is -0.08 to -0.10 MPa;

[0037] In S3, the water temperature in the cooling front section of the vacuum sizing process is 25±2℃, and the water temperature in the cooling rear section is 15±2℃.

[0038] In S3, the traction speed of the vacuum sizing is 0.8 to 1.2 m / min.

[0039] In S4, the heating temperature of the peak during infrared preheating is 210-215℃, and the heating temperature of the trough is 185-195℃.

[0040] In S4, the surface temperature of the flat-walled tube blank during infrared preheating is 165-170°C.

[0041] In S4, the infrared preheating time is 25-35 seconds.

[0042] In S4, the peak pressure during air pressure forming is 0.75±0.05MPa and the trough pressure is 0.65±0.05MPa.

[0043] In S4, the peak pressure holding time during the air pressure forming process is 6-9 seconds, and the trough pressure holding time is 10-13 seconds.

[0044] In S4, the gradient cooling includes pre-cooling, strong cooling, and slow cooling;

[0045] The precooling is achieved by air cooling at a temperature of 35-45°C at the mold inlet.

[0046] The intensive cooling method involves cooling the wave crest to -10 to -20°C at a cooling rate of 40 to 60°C / s.

[0047] The slow cooling method involves cooling the trough to -50 to -60°C at a cooling rate of 3 to 6°C / s.

[0048] After gradient cooling, post-processing is required. Post-processing involves irradiating the product with an electron beam of 50–70 kGy at an energy of 1.5–3.0 MeV, with a local dose at the peak reaching 70–85 kGy. After dimensional correction, the product is then cut and packaged.

[0049] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0050] Compared with the prior art, the beneficial effects of the present invention are:

[0051] 1. This invention uses ultra-high molecular weight polyethylene fibers, which, after selective swelling and immobilization treatment, form a homogeneous interface with the matrix components, thereby significantly improving peel strength. Compared to traditional methods using inorganic fibers, this invention avoids the interface defect problem caused by the poor compatibility between inorganic fibers and matrix components.

[0052] 2. Regarding the molding process, this invention employs dynamic cross-linking controllable molding technology. The DCP / TAIC system can achieve reversible dissociation at processing temperatures, effectively ensuring the stability of the melt flow index, significantly improving the material's processability, and thus greatly increasing the product yield. The cooling method of this invention utilizes peak / trough differential cooling technology. Rapid cooling at the peaks quickly sets the fiber orientation structure, while slow cooling at the troughs helps promote the relaxation and fusion of the matrix component molecular chains, thereby optimizing the material's internal structure. Compared to traditional uniform cooling methods, this cooling technology not only improves cooling efficiency but also has significant energy-saving advantages.

[0053] 3. The HDPE (high molecular weight polyethylene) square-shaped reinforced corrugated pipe of the present invention has excellent mechanical properties. Ring stiffness ≥ 16 kN / m 2 In some preferred embodiments, the strength can reach 16.5–18 kN / m. 2 The high-temperature creep rate is low, with a creep rate of ≤4 after 3000 hours of testing at 40℃, and ≤3.7 in some preferred embodiments; the true impact rate (TIR) ​​during the impact strength test is ≤10%, and 5.5-6.8% in some preferred embodiments. Detailed Implementation

[0054] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0055] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0056] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is understood that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0057] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0058] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0059] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0060] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0061] Unless otherwise specified, the term "or" is inclusive in this invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0062] The raw material information used in the following embodiments is as follows:

[0063] High-density polyethylene (HDPE) was purchased from Zhishun Technology (9011A), with a melt flow index of 0.1–0.6 g / 10 min (190℃, 5 kg) and a density of 0.96 ± 0.03 g / cm³. 3 Tensile strength ≥22MPa, elongation at break ≥150%;

[0064] Ultra-high molecular weight polyethylene (UHMWPE) was purchased from YOCHIC in South Korea. UHMWPE U050 H has a molecular weight of 3.7 million and a particle size of 125 μm.

[0065] Ultra-high molecular weight polyethylene fiber was purchased from Shandong Luxian, with a density of 0.97 g / cm³. 3 Equivalent diameter is 15-20 μm, tensile strength > 3500 MPa, elastic modulus > 95 GPa, and elongation at break is 3-5%;

[0066] Maleic anhydride-grafted SEBS was purchased from Chuanheng Plastics. Its melt index (2.16 kg / 190℃) was 0.5–3.0 g / 10 min, and the grafting rate was 1.0–2.0%.

[0067] The hydroxyl-terminated hyperbranched polyester was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd. as HyPer H302. It is an aromatic hyperbranched polyester with a hydroxyl value of 260 mg KOH / g and a molecular weight of 2500 g / mol.

[0068] The carboxyl-terminated hyperbranched polyester was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd. as HyPer C302. It is a long-chain aromatic polyester with an acid value of 260 mg KOH / g and a molecular weight of 2800 g / mol.

[0069] This includes, but is not limited to, raw materials from the above manufacturers and models.

[0070] Example 1

[0071] 1. The raw materials for preparing the HDPE high molecular weight polyethylene square reinforced corrugated pipe in this embodiment include the following parts by weight: 60 parts high-density polyethylene, 40 parts ultra-high molecular weight polyethylene, 20 parts reinforced polyethylene fiber, 8 parts maleic anhydride grafted SEBS, 1.2 parts dynamic crosslinking agent, 2 parts rheology modifier, 1.0 part UV-resistant composite agent and 0.5 parts lubricant.

[0072] The preparation method of reinforced polyethylene fiber in this embodiment is as follows: ultra-high molecular weight polyethylene fiber is swollen in a mixed solvent of decahydronaphthalene / xylene (mass ratio 3 / 1) at 78°C for 30s, and the fiber diameter expansion rate is controlled at 16%. The swollen ultra-high molecular weight polyethylene fiber is immediately immersed in ethanol at -15 to -20°C for 3 to 8s for immobilization, and the residual solvent is removed by hot air circulation.

[0073] In this embodiment, the mass ratio of DCP to TAIC in the dynamic crosslinking agent is 1:1.2;

[0074] In this embodiment, the rheology modifier is a hydroxyl-terminated hyperbranched polyester;

[0075] In this embodiment, the mass ratio of nano-cerium oxide to light stabilizer (light stabilizer 944) in the UV-resistant composite agent is 1:3;

[0076] The lubricant in this embodiment is polyethylene wax.

[0077] 2. The preparation method of the HDPE high molecular weight polyethylene square reinforced corrugated pipe in this embodiment is as follows:

[0078] S1. Mixing: The dynamic crosslinking agent is dissolved in acetone and then premixed with high-density polyethylene and ultra-high molecular weight polyethylene through atomized spraying. Then, maleic anhydride grafted SEBS, rheology modifier, UV stabilizer and lubricant are added to obtain the mixture.

[0079] S2. Granulation: The mixture is added in the feeding zone and the reinforcing fiber is added in the fiber inlet zone. The mixture is extruded and granulated using a twin-screw granulator. The temperatures of each zone are: feeding zone 160℃, melting zone 190℃, mixing zone 205℃, fiber inlet zone 180℃, homogenization zone 195℃, and die zone 200℃, to obtain blended granules.

[0080] S3. Flat-walled tube blank extrusion: The blended granules are extruded through a single screw extruder and vacuum sizing to obtain a flat-walled tube blank;

[0081] The extrusion speed of the single-screw extruder is 25 rpm, and the pump outlet pressure is 8 MPa.

[0082] The vacuum degree during vacuum sizing is -0.08MPa, the water temperature in the cooling section before vacuum sizing is 25℃ and the water temperature in the cooling section is 15℃, and the traction speed of vacuum sizing is 0.8m / min.

[0083] S4. Square corrugated forming: The flat-walled tube blank is preheated by infrared, formed by air pressure, and cooled by gradient to obtain HDPE high molecular weight polyethylene square reinforced corrugated pipe.

[0084] The infrared preheating time is 30s. During infrared preheating, the heating temperature of the peak is 215℃, the heating temperature of the trough is 190℃, and the surface temperature of the flat-walled tube blank is 170℃.

[0085] During pneumatic molding, the peaks are held at a pressure of 0.75±0.05MPa for 7–9 seconds, and the troughs are held at a pressure of 0.65±0.05MPa for 11–13 seconds.

[0086] Gradient cooling is divided into pre-cooling, strong cooling, and slow cooling. Pre-cooling involves air cooling at 40°C at the mold inlet to initially shape the contour. Strong cooling cools the peak to -15°C at a cooling rate of 50°C / s. Slow cooling cools the trough to -50°C at a cooling rate of 5°C / s.

[0087] After gradient cooling, post-processing is required. Post-processing involves irradiating the product with an electron beam of 55 kGy (with a local peak dose of up to 70 kGy) at an energy of 2.5 MeV, followed by dimensional correction, cutting, and packaging.

[0088] Example 2

[0089] The difference between this embodiment and Embodiment 1 is as follows:

[0090] The raw materials for preparing the HDPE square reinforced corrugated pipe in this embodiment include the following parts by weight: 60 parts high-density polyethylene, 30 parts ultra-high molecular weight polyethylene, 15 parts reinforced polyethylene fiber, 10 parts maleic anhydride grafted SEBS, 1.5 parts dynamic crosslinking agent, 3 parts rheology modifier, 1.2 parts UV-resistant composite agent and 0.3 parts lubricant.

[0091] The other raw materials, steps, and parameters are the same as in Example 1.

[0092] Example 3

[0093] The difference between this embodiment and Embodiment 1 is as follows:

[0094] The raw materials for preparing the HDPE square reinforced corrugated pipe in this embodiment include the following parts by weight: 60 parts high-density polyethylene, 35 parts ultra-high molecular weight polyethylene, 25 parts reinforced polyethylene fiber, 7.3 parts maleic anhydride grafted SEBS, 0.8 parts dynamic crosslinking agent, 2.6 parts rheology modifier, 0.8 parts UV-resistant composite agent, and 0.6 parts lubricant.

[0095] In this embodiment, the mass ratio of DCP to TAIC in the dynamic crosslinking agent is 1:1.5;

[0096] In this embodiment, the rheology modifier is a carboxyl-terminated hyperbranched polyester;

[0097] In this embodiment, the mass ratio of nano-cerium oxide to light stabilizer (light stabilizer 944) in the UV-resistant composite agent is 1:2.5;

[0098] The lubricant in this embodiment is zinc stearate.

[0099] The other raw materials, steps, and parameters are the same as in Example 1.

[0100] Example 4

[0101] The difference between this embodiment and Embodiment 1 is as follows:

[0102] The raw materials for preparing the HDPE square reinforced corrugated pipe in this embodiment include the following parts by weight: 60 parts high-density polyethylene, 40 parts ultra-high molecular weight polyethylene, 22 parts reinforced polyethylene fiber, 9 parts maleic anhydride grafted SEBS, 1.1 parts dynamic crosslinking agent, 0.95 parts anti-ultraviolet composite agent, and 0.43 parts lubricant.

[0103] The other raw materials, steps, and parameters are the same as in Example 1.

[0104] Example 5

[0105] The difference between this embodiment and Embodiment 1 is as follows:

[0106] The preparation method of reinforced polyethylene fiber in this embodiment is as follows: ultra-high molecular weight polyethylene fiber is swollen in a mixed solvent of decahydronaphthalene / xylene (mass ratio 2 / 1) at 80°C for 45s, and the fiber diameter expansion rate is 17%.

[0107] The other raw materials, steps, and parameters are the same as in Example 1.

[0108] Example 6

[0109] The difference between this embodiment and Embodiment 1 is as follows:

[0110] The preparation method of reinforced polyethylene fiber in this embodiment is as follows: ultra-high molecular weight polyethylene fiber is swollen in a mixed solvent of decahydronaphthalene / xylene (mass ratio 1 / 1) at 82°C for 45s, and the fiber diameter expansion rate is controlled at 12%.

[0111] The other raw materials, steps, and parameters are the same as in Example 1.

[0112] Example 7

[0113] The difference between this embodiment and Embodiment 1 is as follows:

[0114] The S3 single-screw extruder has an extrusion speed of 30 rpm and a pump outlet pressure of 10 MPa.

[0115] In S4, the infrared preheating time is 25s, the heating temperature of the peak during infrared preheating is 210℃, the heating temperature of the trough is 190℃, and the surface temperature of the flat-walled tube blank is 165℃.

[0116] The other raw materials, steps, and parameters are the same as in Example 1.

[0117] Example 8

[0118] The difference between this embodiment and Embodiment 1 is as follows:

[0119] In this embodiment, the gradient is divided into strong cooling and slow cooling, without a pre-cooling process; strong cooling cools the peak to -10°C at a cooling rate of 30°C / s; slow cooling cools the trough to -20°C at a cooling rate of 10°C / s.

[0120] The other raw materials, steps, and parameters are the same as in Example 1.

[0121] Comparative Example 1

[0122] The difference between this comparative example and Example 1 is as follows:

[0123] The raw materials for preparing the HDPE square reinforced corrugated pipe of this comparative example include the following parts by weight: 60 parts high-density polyethylene, 35 parts ultra-high molecular weight polyethylene, 9 parts maleic anhydride grafted SEBS, 1.1 parts dynamic crosslinking agent, 2.8 parts rheology modifier, 0.85 parts UV-resistant composite agent, and 0.49 parts lubricant.

[0124] The other raw materials, steps, and parameters are the same as in Example 1.

[0125] Comparative Example 2

[0126] The difference between this comparative example and Example 1 is as follows:

[0127] The raw materials for preparing the HDPE square reinforced corrugated pipe of this comparative example include the following parts by weight: 60 parts high-density polyethylene, 40 parts ultra-high molecular weight polyethylene, 20 parts reinforced polyethylene fiber, 8.4 parts maleic anhydride grafted SEBS, 2.7 parts rheology modifier, 0.8 parts UV stabilizer, and 0.62 parts lubricant.

[0128] The other raw materials, steps, and parameters are the same as in Example 1.

[0129] Comparative Example 3

[0130] The difference between this comparative example and Example 1 is as follows:

[0131] The raw materials for preparing the HDPE square reinforced corrugated pipe of this comparative example include the following parts by weight: 60 parts high-density polyethylene, 35 parts ultra-high molecular weight polyethylene, 20 parts reinforced polyethylene fiber, 0.92 parts dynamic crosslinking agent, 2.3 parts rheology modifier, 1.15 parts UV-resistant composite agent, and 0.52 parts lubricant.

[0132] The other raw materials, steps, and parameters are the same as in Example 1.

[0133] Comparative Example 4

[0134] The difference between this comparative example and Example 1 is as follows:

[0135] S1. Mixing: The dynamic crosslinking agent is dissolved in acetone and then premixed with high-density polyethylene and ultra-high molecular weight polyethylene through atomized spraying. Then, maleic anhydride grafted SEBS, reinforced polyethylene fibers and additives are added to obtain the mixture.

[0136] S2. Granulation: The mixture is added to the feeding zone and extruded into granules using a twin-screw granulator. The temperatures of each zone are: feeding zone 160℃, melting zone 190℃, mixing zone 205℃, homogenization zone 195℃, and die zone 200℃, to obtain blended granules.

[0137] In this comparative example, the reinforced polyethylene fiber is added during mixing, unlike in Example 1 where it is added at the fiber inlet area during granulation. All other raw materials, steps, and parameters are the same as in Example 1.

[0138] Test case

[0139] The HDPE high molecular weight polyethylene square reinforced corrugated pipes prepared in the above embodiments and comparative examples were subjected to the following tests, and the test results are shown in Table 1.

[0140] The ring stiffness test method refers to GB / T9647;

[0141] The impact strength test method refers to GB / T14152, the test temperature is 23±2℃, the impact energy is 25J, and the true impact rate (TIR) ​​is the total number of failures / the total number of impacts.

[0142] The circumferential strain test method refers to GB / T18042, with a test time of 3000h, a test temperature of 40±2℃, and a loading stress of 0.6MPa.

[0143] Table 1

[0144]

[0145]

[0146] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this invention. It should be understood that the above descriptions are merely specific embodiments of this invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. HDPE (high molecular weight polyethylene) square reinforced corrugated pipe, characterized in that, The preparation materials include the following parts by weight: 60 parts high-density polyethylene, 30-50 parts ultra-high molecular weight polyethylene, 10-30 parts reinforced polyethylene fiber, 5-12 parts maleic anhydride grafted SEBS and 0.5-2.0 parts dynamic crosslinking agent; The method for preparing the reinforced polyethylene fiber is as follows: Ultra-high molecular weight polyethylene fiber is swollen in a mixed solvent of decahydronaphthalene / xylene at 78-82℃ for 30-45 seconds, and then the swollen ultra-high molecular weight polyethylene fiber is immediately immobilized by immersing it in ethanol at -15 to -20℃ for 3-8 seconds; the degree of swelling is controlled so that the fiber diameter expansion rate is 15-20%. The dynamic crosslinking agent is dicumyl peroxide and triallyl isocyanurate; The preparation method of the HDPE high molecular weight polyethylene square reinforced corrugated pipe includes the following steps: S1. Mixing: The dynamic crosslinking agent is dissolved in acetone and then premixed with high-density polyethylene and ultra-high molecular weight polyethylene through atomized spraying. Then, maleic anhydride grafted SEBS, reinforced polyethylene fibers and additives are added to obtain the mixture. S2. Granulation: The mixture is added in the feeding zone and the reinforcing fiber is added in the fiber inlet zone. The mixture is extruded and granulated using a twin-screw granulator. The temperatures of each zone are: feeding zone 160℃, melting zone 190℃, mixing zone 205℃, fiber inlet zone 180℃, homogenization zone 195℃, and die zone 200℃, to obtain blended granules. S3. Flat-walled tube blank extrusion: The blended granules are extruded through a single screw extruder and vacuum sizing to obtain a flat-walled tube blank; S4. Square Corrugated Forming: HDPE square reinforced corrugated pipe is obtained by infrared preheating, air pressure forming and gradient cooling of flat wall tube blank.

2. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 1, characterized in that, At least one of the following conditions ① to ④ must be met: ①The equivalent diameter of the ultra-high molecular weight polyethylene fiber is 15~20μm; ②The elastic modulus of the ultra-high molecular weight polyethylene fiber is >95 GPa; ③ The tensile strength of the ultra-high molecular weight polyethylene fiber is >3500MPa; ④ The volume ratio of the decahydronaphthalene / xylene is 3~2:

1.

3. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 1, characterized in that, At least one of the following conditions ① to ④ must be met: ①The Mw of the ultra-high molecular weight polyethylene powder is ≥2.5 million; ②The melt index of the high-density polyethylene at 190℃ and 5kg load is 0.1~0.6g / 10min; ③The melt index of the maleic anhydride-grafted SEBS at 190℃ and 2.16kg load is 0.5~3.0g / 10min; ④ The grafting rate of maleic anhydride grafted onto SEBS is 1.0~2.0%.

4. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 1, characterized in that, The raw materials for preparation also include additives; the additives are 2-5 parts rheology modifier, 0.5-2 parts UV-resistant composite agent and 0.3-0.7 parts lubricant.

5. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 4, characterized in that, At least one of the following conditions ① to ③ must be met: ①The UV-resistant composite agent is nano-cerium oxide and a light stabilizer; ②The lubricant is at least one of polyethylene wax, modified polyethylene wax, mineral oil, potassium stearate, zinc stearate, sodium stearate, and magnesium stearate; ③ The rheology modifier is a hyperbranched polyester.

6. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 1, characterized in that, At least one of the following conditions ① to ⑤ must be met: ①The extrusion speed of the single-screw extruder is 25~30 rpm; ②The pump outlet pressure of the single-screw extruder is ≥8MPa; ③ The vacuum degree of the vacuum calibrator is -0.08 to -0.10 MPa; ④ The water temperature in the cooling section before vacuum sizing is 25±2℃, and the water temperature in the cooling section is 15±2℃; ⑤ The traction speed of the vacuum sizing is 0.8~1.2m / min.

7. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 1, characterized in that, At least one of the following conditions ① to ⑤ must be met: ①The heating temperature of the peak during infrared preheating is 210~215℃, and the heating temperature of the trough is 185~195℃; ②The infrared preheating time is 25~35s; ③ During the air pressure forming process, the peak air pressure is 0.75±0.05MPa and the trough air pressure is 0.65±0.05MPa; ④ The pressure holding time for the peak during the air pressure forming process is 6~9s, and the pressure holding time for the trough is 10~13s; ⑤ The gradient cooling includes pre-cooling, strong cooling, and slow cooling.

8. The HDPE (high molecular weight polyethylene) square reinforced corrugated pipe as described in claim 7, characterized in that, At least one of the following conditions ① to ③ must be met: ①The pre-cooling mentioned above is air cooling at a temperature of 40°C at the mold inlet; ②The strong cooling is to cool the wave crest to -10~-20℃ at a cooling rate of 40~60℃ / s; ③ The slow cooling refers to cooling the trough to -50~-60℃ at a cooling rate of 3~6℃ / s.

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