High-density polyethylene (HDPE) square reinforced corrugated pipe

Abstract

Belonging to the technical field of HDPE corrugated pipe manufacturing, the invention discloses an HDPE high molecular weight polyethylene square reinforced corrugated pipe, which comprises the following preparation raw materials by mass: 60 parts of high density polyethylene, 30-50 parts of ultrahigh molecular weight polyethylene, 10-30 parts of reinforced polyethylene fiber, 5-12 parts of maleic anhydride grafted SEBS and 0.5-2.0 parts of a dynamic cross-linking agent. The preparation method comprises the following steps: S1, mixing materials; S2, granulating; s3, extrusion of a flat-wall pipe blank: extruding the blended granules through a single-screw extruder, and performing vacuum sizing to obtain the flat-wall pipe blank; and S4, square corrugation forming, wherein the flat-wall pipe blank is subjected to infrared preheating, air pressure forming and gradient cooling, and then the HDPE square reinforced corrugated pipe is obtained. The HDPE high molecular weight polyethylene square reinforced corrugated pipe prepared by the invention is high in mechanical strength and good in creep resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of HDPE corrugated pipe manufacturing, specifically HDPE high molecular weight polyethylene square reinforced corrugated pipe. Background Art

[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 light weight, 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 difficult to meet the requirements of large burial depth conditions; when using conventional glass fiber or carbon fiber for reinforcement, due to their poor compatibility with HDPE, it is easy to cause interface delamination, and uneven fiber dispersion will reduce the ring stiffness of the pipe; in addition, traditional formula HDPE corrugated pipes are prone to brittle cracking in high-temperature environments. Although dynamic crosslinking technology can improve its heat resistance to a certain extent, it often sacrifices processing fluidity.

[0003] Currently, to solve the above problems, many studies focus on modifying or pretreating various inorganic fibers. For example, the prior art CN119264540A discloses an HDPE double-wall corrugated pipe reinforcing masterbatch, which uses silane-modified inorganic fibers as reinforcing fibers to improve the ring stiffness and creep resistance of the pipe. However, the compatibility problem between inorganic fibers and polyethylene still exists, which makes the durability of HDPE corrugated pipes poor after long-term use. Summary of the Invention

[0004] To overcome the above technical problems, the present invention provides an HDPE high molecular weight polyethylene square reinforced corrugated pipe. The HDPE high molecular weight polyethylene square reinforced corrugated pipe prepared by the present invention using fiber self-reinforcement and dynamic crosslinking process has high strength and good creep resistance.

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

[0006] The present invention discloses an HDPE high molecular weight polyethylene square reinforced corrugated pipe, which comprises the following raw materials for preparation in parts by mass: 60 parts of high-density polyethylene (HDPE), 30-50 parts of ultra-high molecular weight polyethylene (UHMWPE), 10-30 parts of reinforced polyethylene fiber, 5-12 parts of maleic anhydride grafted SEBS, and 0.5-2.0 parts of 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 mass: 60 parts of high density polyethylene, 30-40 parts of ultra-high molecular weight polyethylene, 15-25 parts of reinforced polyethylene fiber, 8-10 parts of maleic anhydride grafted SEBS, and 0.8-1.5 parts of dynamic crosslinking agent.

[0008] The preparation method of the reinforced polyethylene fiber: The ultra-high molecular weight polyethylene fiber is swollen and immobilized in a decalin / xylene mixed solvent. Among them, decalin is a good solvent for high molecular weight polyethylene fiber, which can effectively penetrate the amorphous region of the fiber and relax the molecular chain; xylene, as an auxiliary solvent, is more likely to rapidly penetrate the surface micropores of the fiber due to its smaller molecular weight than decalin. Solvent penetration relaxes the molecular chains on the fiber surface to form a "sticky outer shell layer" that can be entangled and interlocked with the molecular chains of the matrix component.

[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 > 95 GPa.

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

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

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

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

[0015] In some preferred embodiments, the immobilization is to immediately immerse the swollen ultra-high molecular weight polyethylene fiber in ethanol at -15 to -20 °C for 3-8 s.

[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 ≥ 2.5 million.

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

[0019] In some preferred embodiments, the melt index (at 190 °C, 2.16 kg) of the maleic anhydride grafted SEBS is 0.5 to 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 is used 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) to triallyl isocyanurate (TAIC) in the dynamic crosslinking agent is 1:1.2 to 1.5. Among them, DCP is used as a free radical initiator, and its half-life determines the crosslinking rate; TAIC is a trifunctional crosslinking aid, and a slight excess can ensure sufficient capture of free radicals to avoid degradation caused by unreacted DCP.

[0023] In some preferred embodiments, the preparation raw materials of the HDPE high molecular weight polyethylene square reinforced corrugated pipe further include additives; the additives are 2 to 5 parts of rheological agent, 0.5 to 2 parts of anti-ultraviolet composite agent, and 0.3 to 0.7 parts of lubricant; preferably, the additives are 2 to 3 parts of rheological agent, 0.7 to 1.2 parts of anti-ultraviolet composite agent, and 0.3 to 0.7 parts of lubricant.

[0024] In some preferred embodiments, the anti-ultraviolet composite agent is nano-ceria and a light stabilizer. Preferably, the mass ratio of nano-ceria to the light stabilizer in the anti-ultraviolet composite agent 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 rheological agent is a hyperbranched polyester; the rheological agent is a hyperbranched polyester with terminal hydroxyl groups or a hyperbranched polyester with terminal carboxyl groups;

[0028] In the present invention, for the HDPE high molecular weight polyethylene square reinforced corrugated pipe, its preparation method includes the following steps:

[0029] S1. Blending: Dissolve the dynamic crosslinking agent in acetone, then premix it with high-density polyethylene and ultra-high molecular weight polyethylene by atomized spraying, and then add maleic anhydride grafted SEBS, reinforced polyethylene fiber and additives to obtain a blended material;

[0030] S2. Pelletizing: Use a twin-screw pelletizer to extrude and pelletize the blended material;

[0031] S3. Extrusion of flat-wall tube blank: Extrude the blended pellets through a single-screw extruder and then subject them to vacuum sizing to obtain a flat-wall tube blank;

[0032] S4. Square corrugation forming: Infrared preheat the flat-wall tube blank, form it by air pressure, and then cool it by gradient to obtain an HDPE square reinforced corrugated pipe.

[0033] In S2, the temperature of each zone of the twin-screw extruder: feeding zone 160±3°C - melting zone 190±2°C - mixing zone 205±2°C - fiber inlet zone 180±2°C - homogenizing zone 195±3°C - die head zone 200±2°C;

[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 ≥8 MPa;

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

[0037] In S3, the water temperature at the front stage of cooling in the vacuum sizing is 25±2°C, and the water temperature at the rear stage is 15±2°C;

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

[0039] In S4, the heating temperature at the wave peak during infrared preheating is 210 - 215°C, and the heating temperature at the wave valley is 185 - 195°C.

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

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

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

[0043] In S4, the wave peak pressure holding time during air pressure forming is 6 - 9 s, and the wave valley pressure holding time is 10 - 13 s.

[0044] In S4, the gradient cooling includes precooling, intensive cooling, and slow cooling;

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

[0046] The intensive cooling is to cool the wave crest to -10 to -20°C at a cooling rate of 40 - 60°C / s;

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

[0048] After gradient cooling, post - treatment is required. The post - treatment is to irradiate with an electron beam of 50 - 70 kGy with an energy of 1.5 - 3.0 MeV. The local dose at the wave crest can reach 70 - 85 kGy. After size correction, cutting and packaging can be carried out.

[0049] On the basis of conforming to the common knowledge in the art, the above - mentioned preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

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

[0051] 1. The present invention uses ultra - high - molecular - weight polyethylene fibers. After selective swelling - immobilization treatment, a homogeneous interface is formed with the matrix component, thus significantly improving the peel strength. Compared with the traditional method of using inorganic fibers, the present invention avoids the interface defect problem caused by the poor compatibility between inorganic fibers and matrix components.

[0052] 2. In terms of the forming process, the present invention adopts a dynamic cross - linking controllable forming technology. Among them, the DCP / TAIC system can achieve reversible dissociation at the processing temperature, effectively ensuring the stability of the melt index, significantly improving the processability of the material, and thus greatly increasing the yield rate of the product. The cooling method of the present invention uses a wave - crest / wave - trough differential cooling technology. The rapid cooling at the wave crest can quickly fix the orientation structure of the fibers, while the slow cooling at the wave trough helps to promote the relaxation and fusion of the molecular chains of the matrix component, thereby optimizing the internal structure of the material. Compared with the traditional uniform cooling method, this cooling technology not only improves the cooling efficiency but also has significant energy - saving advantages.

[0053] 3. The mechanical properties of the HDPE high - molecular - weight polyethylene square reinforced corrugated pipe of the present invention are excellent. The ring stiffness ≥ 16 kN / m 2 , and in some preferred embodiments, it can reach 16.5 - 18 kN / m 2 ; the high - temperature creep rate is low, the creep rate at 40°C for a test time of 3000 h is ≤ 4, and in some preferred embodiments, it is ≤ 3.7; the true impact rate TIR during the impact strength test is ≤ 10%, and in some preferred embodiments, it is 5.5 - 6.8%. Detailed implementation mode

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

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

[0056] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can include or exclude the end values 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 a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present invention, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0057] If there is no special indication, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0058] If there is no special indication, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0059] Unless otherwise specified, all steps of the present invention can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

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

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

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

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

[0064] Ultra-high molecular weight polyethylene (UHMWPE) was purchased from Korea Yuhwa UHMWPE U050 H, with 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 / cm 3 , an equivalent diameter of 15 - 20 μm, a tensile strength > 3500 MPa, an elastic modulus > 95 GPa, and an elongation at break of 3 - 5%;

[0066] Maleic anhydride grafted SEBS was purchased from Chuanheng Plastics, with a melt index (2.16 kg / 190 °C) of 0.5 - 3.0 g / 10 min and a grafting rate of 1.0 - 2.0%;

[0067] The hydroxyl-terminated hyperbranched polyester was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., HyPer H302, which 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., HyPer C302, which has a long-chain aromatic polyester structure, an acid value of 260 mg KOH / g, and a molecular weight of 2800 g / mol.

[0069] Raw materials include but are not limited to the above manufacturer models.

[0070] Example 1

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

[0072] The preparation method of the reinforced polyethylene fiber in this example: The ultra-high molecular weight polyethylene fiber is swollen in a mixed solvent of decahydronaphthalene / xylene (mass ratio 3 / 1) at 78 °C for 30 s, 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 8 s for immobilization, and the residual solvent is removed by hot air circulation.

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

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

[0075] In this example, the mass ratio of nano-ceria to light stabilizer (light stabilizer 944) in the anti-ultraviolet composite agent is 1:3;

[0076] In this example, the lubricant is polyethylene wax.

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

[0078] S1. Mixing: The dynamic crosslinking agent is dissolved in acetone and premixed with high density polyethylene and ultra-high molecular weight polyethylene by atomized spraying, and then maleic anhydride grafted SEBS, rheology modifier, anti-ultraviolet composite agent, and lubricant are added to obtain a mixed material;

[0079] S2. Pelletizing: Add the mixed materials in the feeding area and the reinforcing fibers in the fiber inlet area. Use a twin-screw pelletizer to extrude and pelletize the mixed materials. The temperature of each zone is as follows: feeding area 160°C - melting zone 190°C - mixing zone 205°C - fiber inlet area 180°C - homogenizing zone 195°C - die head zone 200°C to obtain the blended pellets;

[0080] S3. Flat-wall tube blank extrusion: Extrude the blended pellets through a single-screw extruder and then perform vacuum sizing to obtain a flat-wall tube blank;

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

[0082] During vacuum sizing, the vacuum degree is -0.08 MPa, the water temperature at the front section of vacuum sizing and cooling is 25°C, the water temperature at the rear section is 15°C, and the traction speed of vacuum sizing is 0.8 m / min;

[0083] S4. Square corrugation forming: Infrared preheat the flat-wall tube blank, perform pneumatic forming, and gradient cooling to obtain an HDPE high molecular weight polyethylene square reinforced corrugated pipe;

[0084] The infrared preheating time is 30 s. During infrared preheating, the heating temperature at the wave crest is 215°C, the heating temperature at the wave trough is 190°C, and the surface temperature of the flat-wall tube blank is 170°C;

[0085] During pneumatic forming, the wave crest is kept under pressure at 0.75 ± 0.05 MPa for 7 - 9 s, and the wave trough is kept under pressure at 0.65 ± 0.05 MPa for 11 - 13 s;

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

[0087] After gradient cooling, post-treatment is required. The post-treatment is electron beam irradiation with an energy of 2.5 MeV and a dose of 55 kGy (the local dose at the wave crest can reach 70 kGy), and then perform size correction and cutting and packaging.

[0088] Example 2

[0089] The difference between this example and Example 1 is:

[0090] The raw materials for preparing the HDPE high molecular weight polyethylene square reinforced corrugated pipe in this example include the following parts by mass of raw materials: 60 parts of high-density polyethylene, 30 parts of ultra-high molecular weight polyethylene, 15 parts of reinforced polyethylene fiber, 10 parts of maleic anhydride grafted SEBS, 1.5 parts of dynamic cross-linking agent, 3 parts of rheological agent, 1.2 parts of anti-ultraviolet composite agent, and 0.3 part of lubricant;

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

[0092] Example 3

[0093] The difference between this example and Example 1 lies in:

[0094] The raw materials for preparing the HDPE high molecular weight polyethylene square reinforced corrugated pipe in this example include the following parts by mass of raw materials: 60 parts of high density polyethylene, 35 parts of ultra-high molecular weight polyethylene, 25 parts of reinforced polyethylene fiber, 7.3 parts of maleic anhydride grafted SEBS, 0.8 part of dynamic crosslinking agent, 2.6 parts of rheological agent, 0.8 part of anti-ultraviolet composite agent and 0.6 part of lubricant;

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

[0096] In this example, the rheological agent is a carboxyl-terminated hyperbranched polyester;

[0097] In this example, the mass ratio of nano-ceria to light stabilizer (light stabilizer 944) in the anti-ultraviolet composite agent is 1:2.5;

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

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

[0100] Example 4

[0101] The difference between this example and Example 1 lies in:

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

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

[0104] Example 5

[0105] The difference between this example and Example 1 lies in:

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

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

[0108] Example 6

[0109] The difference between this example and Example 1 is that:

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

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

[0112] Example 7

[0113] The difference between this example and Example 1 is that:

[0114] In S3, the extrusion speed of the single-screw extruder is 30 rpm, and the pump outlet pressure is 10 MPa;

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

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

[0117] Example 8

[0118] The difference between this example and Example 1 is that:

[0119] The gradient in this example is divided into strong cooling and slow cooling, and there is no pre-cooling process; for strong cooling, the wave peak is cooled to -10 °C at a cooling rate of 30 °C / s; for slow cooling, the wave trough is cooled to -20 °C at a cooling rate of 10 °C / s.

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

[0121] Comparative Example 1

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

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

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

[0125] Comparative Example 2

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

[0127] The raw materials for preparing the HDPE high molecular weight polyethylene square reinforced corrugated pipe in this comparative example include the following parts by mass of raw materials: 60 parts of high density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of reinforced polyethylene fiber, 8.4 parts of maleic anhydride grafted SEBS, 2.7 parts of rheological agent, 0.8 part of anti-ultraviolet composite agent, and 0.62 part of lubricant.

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

[0129] Comparative Example 3

[0130] The difference between this comparative example and Example 1 lies in:

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

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

[0133] Comparative Example 4

[0134] The difference between this comparative example and Example 1 lies in:

[0135] S1. Mixing: Dissolve the dynamic crosslinking agent in acetone and premix it with high density polyethylene and ultra-high molecular weight polyethylene by atomized spraying, and then add maleic anhydride grafted SEBS, reinforced polyethylene fiber and additives to obtain a mixed material;

[0136] S2. Pelletizing: Add the mixed material in the feeding zone, and use a twin-screw pelletizing machine to extrude and pelletize the mixed material. The temperature of each zone is: feeding zone 160°C - melting zone 190°C - mixing zone 205°C - homogenizing zone 195°C - die head zone 200°C to obtain a blended pellet;

[0137] The reinforced polyethylene fiber in this comparative example is added during mixing, unlike in Example 1 where it is added in the fiber inlet zone during pelletizing. Other raw materials, steps and parameters are the same as those in Example 1.

[0138] Test Example

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

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

[0141] The impact strength test method refers to GB / T 14152. The test temperature is 23 ± 2 °C, the impact energy is 25 J, and the true impact rate TIR, that is, the total number of failures / the total number of impacts;

[0142] The circumferential strain test method refers to GB / T 18042. The test time is 3000 h, the test temperature is 40 ± 2 °C, and the applied stress is 0.6 MPa.

[0143] Table 1

[0144]

[0145]

[0146] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods. The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. HDPE high molecular weight polyethylene square reinforced corrugated pipe, characterized in that, The preparation raw materials include the following parts by mass: 60 parts of high-density polyethylene, 30 - 50 parts of ultra-high molecular weight polyethylene, 10 - 30 parts of reinforced polyethylene fiber, 5 - 12 parts of maleic anhydride grafted SEBS, and 0.5 - 2.0 parts of dynamic crosslinking agent.

2. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 1, characterized in that, The preparation method of the reinforced polyethylene fiber: swelling the ultra-high molecular weight polyethylene fiber in a mixed solvent of decalin / xylene and then immobilizing it.

3. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 2, wherein Meet at least one of the following conditions ① - ⑦: ① The equivalent diameter of the ultra-high molecular weight polyethylene fiber is 15 - 20 μm; ② The elastic modulus of the ultra-high molecular weight polyethylene fiber > 95 GPa; ③ The tensile strength of the ultra-high molecular weight polyethylene fiber > 3500 MPa; ④ The volume ratio of decalin / xylene is 3 - 2:1; ⑤ The swelling temperature is 78 - 82 °C, and the swelling time is 30 - 45 s; ⑥ The swelling degree of the swelling is to control the fiber diameter expansion rate at 15 - 20%; ⑦ The immobilization is to immediately immerse the swollen ultra-high molecular weight polyethylene fiber in ethanol at -15 - -20 °C for 3 - 8 s.

4. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 1, characterized in that Meet at least one of the following conditions ① - ⑤: ① The Mw of the ultra-high molecular weight polyethylene powder ≥ 2.5 million; ② The melt index of the high-density polyethylene at 190 °C and 5 kg load is 0.1 - 0.6 g / 10 min; ③ The melt index of the maleic anhydride grafted SEBS at 190 °C and 2.16 kg load is 0.5 - 3.0 g / 10 min; ④ The grafting rate of the maleic anhydride grafted SEBS is 1.0 - 2.0%; ⑤ The dynamic crosslinking agent is dicumyl peroxide and triallyl isocyanurate.

5. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 1, characterized in that, The preparation raw materials also include additives; the additives are 2 - 5 parts of rheological agent, 0.5 - 2 parts of anti-ultraviolet composite agent, and 0.3 - 0.7 parts of lubricant.

6. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 5, characterized in that, Meet at least one of the following conditions ① - ③: ① The anti-ultraviolet composite agent is nano-ceria and light stabilizer; ② The lubricant is at least one of polyethylene wax, modified polyethylene wax, mineral oil, potassium stearate, zinc stearate, sodium stearate, magnesium stearate; ③ The rheological agent is hyperbranched polyester.

7. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to any one of claims 1 to 6, characterized in that, Its preparation method includes the following steps: S1. Mixing: Dissolve the dynamic crosslinking agent in acetone, and then premix it with high-density polyethylene and ultra-high molecular weight polyethylene by atomized spraying, and then add maleic anhydride grafted SEBS, reinforced polyethylene fiber and additives to obtain a mixed material; S2. Pelletizing: Use a twin-screw extruder to extrude and pelletize the mixed material; S3. Flat wall tube blank extrusion: Extrude the blended pellets through a single-screw extruder and then vacuum sizing to obtain a flat wall tube blank; S4. Square corrugation forming: Infrared preheat the flat wall tube blank, pneumatically form it, and then gradient cool it to obtain an HDPE square reinforced corrugated pipe.

8. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 7, characterized in that, Meet at least one of the following conditions ① - ⑥: ① The temperature of each zone of the twin-screw extruder: feeding zone 160 ± 3 °C - melting zone 190 ± 2 °C - mixing zone 205 ± 2 °C - fiber inlet zone 180 ± 2 °C - homogenizing zone 195 ± 3 °C - die head zone 200 ± 2 °C; ② The extrusion speed of the single-screw extruder is 25 - 30 rpm; ③ The pump outlet pressure of the single-screw extruder ≥ 8 MPa; ④ The vacuum degree of the vacuum sizing is -0.08 to -0.10 MPa; ⑤ The water temperature at the front stage of cooling in the vacuum sizing is 25 ± 2 °C, and the water temperature at the rear stage is 15 ± 2 °C; ⑥ The traction speed of the vacuum sizing is 0.8 to 1.2 m / min.

9. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 7, characterized in that, Meet at least one of the following conditions ① to ⑤: ① The heating temperature at the wave peak during the infrared preheating is 210 to 215 °C, and the heating temperature at the wave trough is 185 to 195 °C; ② The time of the infrared preheating is 25 to 35 s; ③ The wave peak air pressure during the pneumatic forming is 0.75 ± 0.05 MPa, and the wave trough air pressure is 0.65 ± 0.05 MPa; ④ The wave peak pressure holding time during the pneumatic forming is 6 to 9 s, and the wave trough pressure holding time is 10 to 13 s; ⑤ The gradient cooling includes pre-cooling, strong cooling, and slow cooling.

10. The HDPE high molecular weight polyethylene square reinforced corrugated pipe according to claim 9, characterized in that, Meet at least one of the following conditions ① to ③: ① The pre-cooling is air cooling at a temperature of 40 °C at the mold inlet; ② The strong cooling cools the wave peak to -10 to -20 °C at a cooling rate of 40 to 60 °C / s; ③ The slow cooling cools the wave trough to -50 to -60 °C at a cooling rate of 3 to 6 °C / s.

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