Mica reinforced and modified high-rigidity double-wall corrugated pipe as well as preparation method and application thereof

Abstract

The invention discloses a mica reinforced and modified high-rigidity double-wall corrugated pipe as well as a preparation method and application thereof, and relates to the technical field of pipeline preparation. Comprising the following steps: mixing modified mica powder, high-density polyethylene and a compatilizer to prepare a high-rigidity integrated material, and then carrying out melt blending extrusion molding on the high-rigidity integrated material. The modified mica powder comprises the step of modifying the mica powder by adopting a coupling agent. The mica powder is modified, the coupling agent is used for treating the mica powder, the coupling agent can enter mica layers through ultrasonic dispersion modification, the compatibility and dispersity of the mica are improved, the mechanical property of the mica is improved, and the phenomenon that the structure of the mica powder is damaged by mechanical shearing in the material mixing process is avoided; and the mechanical property and the quality stability of the double-wall corrugated pipe are ensured. The double-wall corrugated pipe provided by the invention has the characteristics of high ring stiffness and excellent impact resistance, realizes rigidity-toughness balance, and is suitable for application occasions with higher external load and / or severe geological environment.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline preparation, and in particular to a mica-reinforced and modified high-rigidity double-wall corrugated pipe, a preparation method thereof, and applications thereof. Background Art

[0002] With the continuous improvement of the performance of polymer materials such as polyolefins, polyesters, polyamides, and polyurethanes, pipes made from these materials have gradually become chemically resistant, non-toxic, inexpensive, and pressure-resistant. As a result, they have gradually replaced traditional cast iron and reinforced concrete pipes in municipal engineering. Furthermore, in the municipal drainage and sewage market, double-wall corrugated pipes of the same size offer lighter weight and higher hoop stiffness than traditional polyethylene (PE) solid-wall pipes. Therefore, double-wall corrugated pipes have become the mainstream product for large-diameter municipal drainage and sewage pipes.

[0003] To further enhance the mechanical properties of double-wall corrugated pipes, reinforcing masterbatches, such as mica, are commonly added to the raw materials. Mica, which often has a flaky structure and a high aspect ratio, is widely used in plastic modification. When incorporated into polymers such as polyolefins, polyesters, polyamides, and polyurethanes, it can significantly improve the flexural strength, tensile strength, and tear resistance of the resulting composites.

[0004] However, double-wall corrugated pipe production currently relies primarily on a compounding process, where raw materials, reinforcing masterbatch, and other processing aids are mixed at high speed before being fed into an extruder. Due to mica's high diameter-to-thickness ratio and flaky structure, it is prone to structural damage during preparation and processing, resulting in poor resin modification. Furthermore, uneven distribution of raw material components during transportation and mixing can lead to significant fluctuations in the mechanical properties of the final product, compromising product quality and stability.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a mica-reinforced and modified high-rigidity double-wall corrugated pipe and a preparation method and application thereof.

[0007] The present invention is achieved in that: In a first aspect, the present invention provides a method for preparing a mica-reinforced modified high-rigidity double-wall corrugated pipe, comprising mixing modified mica powder, high-density polyethylene and a compatibilizer to prepare a high-rigidity integral material, and then melt-blending and extruding the high-rigidity integral material.

[0008] The preparation of modified mica powder includes using a coupling agent to perform ultrasonic mixing modification on the mica powder.

[0009] In a second aspect, the present invention provides a mica-reinforced and modified high-rigidity double-wall corrugated pipe, which is prepared by the preparation method of any one of the aforementioned embodiments.

[0010] In a third aspect, the present invention provides an application of a double-wall corrugated pipe according to the aforementioned embodiment in a drainage or sewage pipe system.

[0011] The present invention has the following beneficial effects: The present invention provides a mica-reinforced, modified, high-rigidity double-wall corrugated pipe, as well as a preparation method and application thereof. The invention involves modifying mica powder, treating the mica powder with a coupling agent, and then subjecting the mica powder to ultrasonic dispersion modification, allowing the coupling agent to penetrate between mica layers, thereby improving the compatibility and dispersibility of the mica and enhancing the mechanical properties of the mica. This prevents mechanical shear damage to the mica powder structure during material mixing, thereby ensuring the mechanical properties and quality stability of the double-wall corrugated pipe. The double-wall corrugated pipe provided by the present invention combines high ring stiffness with excellent impact resistance, achieving a balanced rigidity and toughness, and is suitable for applications with high external loads and / or harsh geological environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 This is a flow chart of the method for preparing the mica-reinforced and modified high-rigidity double-wall corrugated pipe provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0014] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0015] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0016] In a first aspect, the present invention provides a method for preparing a mica-reinforced modified high-rigidity double-wall corrugated pipe, comprising mixing modified mica powder, high-density polyethylene and a compatibilizer to prepare a high-rigidity integral material, and then melt-blending and extruding the high-rigidity integral material.

[0017] The preparation of modified mica powder includes using a coupling agent to perform ultrasonic mixing modification on the mica powder.

[0018] Each mica particle in the mica powder is a flaky structure, and the mica flakes have a high diameter-to-thickness ratio. Therefore, as a reinforcing masterbatch for polymer materials such as polyolefins, it can significantly improve the comprehensive performance of the material. However, due to process influences, the structure of the mica flakes is easily destroyed during the mixing process, resulting in poor performance of the material. The present invention uses a coupling agent to perform ultrasonic dispersion modification on the mica powder. The coupling agent can improve the compatibility and dispersibility of the mica, improve the mechanical properties of the mica, avoid mechanical shearing during the mixing of materials to destroy the structure of the mica powder, and ensure the mechanical properties and quality stability of the double-walled corrugated pipe. The double-walled corrugated pipe provided by the present invention has the characteristics of high ring stiffness and excellent impact resistance, achieves a balance between rigidity and toughness, and is suitable for applications with high external loads and / or harsh geological environments.

[0019] In some embodiments, the present invention provides a method for preparing a mica-reinforced and modified high-rigidity double-wall corrugated pipe comprising the following steps: S01. Preparation of modified mica powder In an optional embodiment, the method for preparing modified mica powder includes: mixing a dispersant, a coupling agent and a solvent to prepare a mixed solution, dispersing the mica powder in the mixed solution and performing ultrasonic mixing modification, and drying the solid in the mixed solution after modification.

[0020] Preferably, in order to ensure uniform dispersion of the coupling agent, the dispersant and the coupling agent are first mixed to obtain a mixing aid, and then the mixing aid is dissolved in a solvent to obtain a mixed solution.

[0021] Preferably, the coupling agent includes one or more of a silane coupling agent, a titanate coupling agent or an aluminate coupling agent; more preferably, the coupling agent is KH550.

[0022] Preferably, the dispersant includes at least one of polyethylene glycol (PEG) or polyvinyl pyrrolidone (PVP). The selection of the above dispersant raw materials facilitates efficient dispersion of the coupling agent KH550.

[0023] And / or, the mass ratio of the dispersant to the coupling agent is 1 to 3:1, for example, any value selected from 1:1, 1.5:1, 2:1, 2.5:1, or 3:1, or a range between any two values. Controlling the ratio of the dispersant to the coupling agent within this range facilitates sufficient dispersion of the coupling agent.

[0024] And / or, in order to ensure that each mica flake in the mica powder is uniformly modified, it is necessary to increase the dispersion of the coupling agent in the solution. Therefore, a solvent is added to the mixed auxiliary agent formed by the dispersant and the coupling agent to further disperse the two. The total concentration of the dispersant and the coupling agent in the solvent is 2-5 wt%.

[0025] And / or, the solvent comprises an ethanol-water mixed solvent, wherein the volume ratio of ethanol to water in the ethanol-water mixed solvent is 3-5:1, preferably 4:1.

[0026] And / or, in order to further improve the comprehensive performance of the double-wall corrugated pipe, the diameter-to-thickness ratio of the mica powder is greater than or equal to 80.

[0027] And / or, the process of modifying the mica powder in the mixed solution further includes adding nano-montmorillonite into the mixed solution.

[0028] That is, in some embodiments, mica powder can be added alone to the mixed solution, or a mixed solid of mica powder and nano-montmorillonite can be added to the mixed solution.

[0029] Preferably, a mixed solid of mica powder and nano-montmorillonite is added to the mixed solution, with the mass ratio of nano-montmorillonite to mica powder being 1:8-10. This is because adding a small amount of nano-montmorillonite to the mica powder can further enhance the interfacial bonding between the mica powder and the coupling agent by utilizing the layered structure and ion exchange capacity of the nano-montmorillonite, thereby improving the overall performance of the double-wall corrugated pipe.

[0030] And / or, during the modification of the mica powder in the mixed solution, the mass-to-volume ratio of the solid material to the mixed solution is 60-80 g:1 mL. By controlling the contents of the solid material and the mixed solution, the mica powder can be fully exposed to the coupling agent for modification, thereby improving the overall performance of the mica powder.

[0031] When only modified mica powder is added to the mixed solution, the solid material is the modified mica powder, and the mass volume ratio of the modified mica powder to the mixed solution is 60~80g:1mL; when modified mica powder and nano-montmorillonite are added to the mixed solution, the solid material is the modified mica powder and nano-montmorillonite, and the ratio of the total mass of the modified mica powder and nano-montmorillonite to the volume of the mixed solution is 60~80g:1mL.

[0032] And / or, during the modification process, the ultrasonic temperature is 40-50°C, the ultrasonic time is 30-60 minutes, the ultrasonic frequency is 20-30 kHz, and the ultrasonic power is 300-500 W. Through ultrasonic dispersion modification, the cavitation effect generated during the ultrasonic process can promote the penetration of KH550 molecules into the mica interlayers while preventing mechanical shear damage to the mica sheets.

[0033] Preferably, the process further comprises performing solid-liquid separation on the suspension obtained after modification, and drying the solid phase to completely remove the residual solvent in the solid. More preferably, the drying is performed by vacuum drying, and the modified mica powder is obtained after drying. S02. Preparation of high-rigidity integrated material In an optional embodiment, the preparation of the high-rigidity integral material comprises mixing a mixed melt of modified mica powder, high-density polyethylene and a compatibilizer using a twin-screw extruder.

[0034] In an optional embodiment, the mass ratio of modified mica powder, high-density polyethylene and compatibilizer is: 20~80:40~80:2~10.

[0035] And / or, the compatibilizer includes any one of maleic anhydride grafted polyethylene or methacrylic acid grafted polyethylene.

[0036] Preferably, the mixed melt adopts twin-screw extruder to mix, and the two screw rods of twin-screw extruder rotate in the same direction.The melt viscosity of high-density polyethylene is relatively low, and fluidity is good, and modified mica powder is easily agglomerated in high-density polyethylene melt, adopts the distributed mixing of twin-screw extruder, i.e. non-high-intensity shearing, not only can be conducive to the dispersion of modified mica powder, and the structure of modified mica powder can be avoided from being destroyed. In addition, the self-cleaning property and controlled shearing characteristics of co-rotating twin-screw are more suitable for high-filling system, and single-screw shear rate distribution is uneven, and melting section easily forms high shear zone, and mixing ability is weak, is only suitable for low-filling or shear-insensitive system, and the structure of co-rotating twin-screw can also more effectively avoid the problem that single-screw causes mica particles to be broken because of local shearing too high.

[0037] In an optional embodiment, the screw parameters of the twin-screw extruder include at least one of the following 1) to 8).

[0038] 1) The aspect ratio of the screw is 28~36:1, and the length of the melting section accounts for 30~40% of the total screw length, and the length of the mixing section accounts for 40~50% of the total screw length.

[0039] Since the melting point of high-density polyethylene (HDPE) is approximately 120-30°C, sufficiently long melting and mixing sections are required. Furthermore, the screw's aspect ratio must be controlled within the above range to ensure gradual dispersion of the modified mica powder under low shear conditions. A high screw aspect ratio can increase energy consumption and easily lead to shear overheating, which is detrimental to the dispersion of HDPE and modified mica powder.

[0040] 2) The pitch of the feeding section of the screw is 1.2~1.5 times the screw diameter, and the screw groove depth is 0.15~0.2 times the screw diameter.

[0041] The feeding section adopts large pitch and shallow thread to quickly transport materials, avoid the accumulation of modified mica powder at the feeding port, and reduce the initial compression shear force.

[0042] 3) The pitch of the melting section of the screw is a gradual pitch, and the pitch transitions from 1.15 to 1.25 times the screw diameter to 0.95 to 1.05 times the screw diameter along the direction from the feeding section to the mixing section. In an optional embodiment, the compression ratio of the mixed melt in the melting section is 1.8 to 2.2.

[0043] When the mixed melt enters the melting section, the density of the high-density polyethylene changes. The mixed melt needs to be moderately compressed to gently melt the high-density polyethylene and avoid shear shock caused by sudden compression.

[0044] 4) The melting section of the screw also features shallow-toothed kneading blocks as threaded elements. These blocks are staggered at an angle of 30-45° and 10-15 mm thick. Each screw contains two to three sets of these blocks, with the spacing between adjacent blocks being two to three times the screw diameter. These blocks facilitate the melting of high-density polyethylene and the dispersion of modified mica powder.

[0045] 5) The pitch of the mixing section and the homogenizing section of the screw is 0.95~1.05 times the screw diameter, and the screw groove is 0.2~0.25 times the screw diameter. By controlling the mixing section and the homogenizing section to have equal pitch and deep screw groove structure, combined with low shear mixing (shear rate controlled at 500~800 s - ¹) To achieve the dispersion of modified mica powder.

[0046] 6) The screws in the mixing section and homogenizing section are equipped with reverse conveying blocks and / or barrier-type threads. The staggered angle of the reverse conveying blocks is 55-65°, and each screw is equipped with 1-2 sets of reverse conveying blocks. The reverse conveying blocks and barrier-type threads can reduce the retention of the mixed melt and prevent the modified mica powder from being destroyed due to retention.

[0047] 7) The screw surface features a micro-pit array structure, with each pit measuring 50-100 μm in diameter and 20-30 μm in depth, with a spacing of 200-300 μm between adjacent pits. This micro-pit array structure allows the twin-screw extruder to rotate at high speed during mixing, forming an air film. This further reduces direct contact between the modified mica powder and the screw surface, preventing structural damage to the modified mica powder.

[0048] 8) The twin-screw extruder's die channel has an aspect ratio of 8-10:1, with a convergence angle of 30° or less. By controlling die parameters within this range, a streamlined die structure is created, which reduces shearing at the exit and prevents damage to the modified mica flakes.

[0049] In an optional embodiment, the parameters of the mixing process of the modified mica powder, high-density polyethylene and the compatibilizer include at least one of the following 1) to 3).

[0050] 1) The speed of the twin-screw extruder is 50-80 rpm. When the speed of the twin-screw extruder is too high, for example, greater than or equal to 100 rpm, the modified mica sheets are easily broken due to the increased shear force, which destroys the diameter-to-thickness ratio of the modified mica sheets and the modified film structure on the surface, affecting the overall performance of the double-wall corrugated pipe.

[0051] Preferably, the feeding speed is linked to the rotation speed of the twin-screw extruder, and the feeding speed is controlled by the rotation speed of the twin-screw extruder to avoid material piling.

[0052] 2) The temperature of the feeding section is 140~150℃, the temperature of the melting section is 170~180℃, the temperature of the mixing section is 180~190℃, the temperature of the homogenizing section is 190~200℃, and the temperature of the die head is 180~190℃.

[0053] By controlling the temperature of the feeding section within 140-150°C, slightly above the softening point of HDPE, material agglomeration can be effectively avoided. By controlling the temperature of the mixing section to not exceed 200°C, the oxidative degradation of HDPE can be effectively prevented, while the viscosity of the mixed melt can be reduced, thereby reducing the shear force on the mixed melt.

[0054] 3) The vacuum degree in the mixing section is 0.05-0.08 MPa. By providing an exhaust port at the end of the mixing section, volatile substances in the mixed melt and moisture adsorbed on the surface of the modified mica powder are discharged after the mixed melt is evenly mixed and before discharging, ensuring the performance of the high-rigidity integrated material, facilitating the formation of double-wall corrugated tubes with good morphology and structure, and avoiding defects such as bubbles.

[0055] By controlling the screw parameters and process parameters of the twin-screw extruder, the modified mica powder is subjected to a smaller shear force in the initial stage of mixing, and then the shear force is gradually increased and the shear force at the outlet is reduced, ultimately achieving uniform dispersion of the modified mica flakes in high-density polyethylene.

[0056] S03, Double-wall corrugated pipe forming process In an optional embodiment, the melt blending extrusion molding includes extrusion using a single-screw extruder, and parameters of the extrusion process of the single-screw extruder include at least one of the following 1) to 3).

[0057] 1) The feeding section temperature is 185-195°C, which is 5-15°C higher than the feeding section temperature of 180-190°C in the existing molding process. This reduces the friction resistance between the modified mica powder and the screw and avoids clogging of the feeding section.

[0058] The temperature of the compression section is 200~210℃. The compression section is the key temperature rising area. The higher temperature promotes the melting of high-density polyethylene and wraps the modified mica particles, reducing the agglomeration of modified mica powder. At this time, the viscosity of the melt is high and higher energy is required for melting.

[0059] The temperature of the metering section is 210~220℃, which can ensure uniform mixing of the melt and avoid the occurrence of local unmelted particles.

[0060] The die head temperature is 210-220°C. By increasing the die head temperature, the resistance of the melt through the die head is reduced, avoiding the risk of excessive die pressure caused by process adjustments when using existing molds. This also reduces the risk of orientation of the modified mica powder. Therefore, the process provided by the present invention can be applied to existing equipment and molds, eliminating the additional cost of new mold processing, resulting in greater applicability and better double-wall corrugated pipe performance.

[0061] The die temperature is 205~215℃; since the inner and outer walls of the double-wall corrugated pipe need to be formed synchronously, the die temperature is fine-tuned to ensure that the flow rate of the inner and outer layers of the melt is consistent, avoiding wall thickness deviation caused by uneven distribution of modified mica powder.

[0062] 2) The speed of the single-screw extruder is 20~35rpm, and the back pressure is 0.3~0.8MPa.

[0063] By controlling the speed of the single-screw extruder within the above range, the molding process of the modified mica powder is facilitated. When the speed is too high, the mica flakes in the modified mica powder will be broken or over-oriented, that is, arranged along the flow direction, thereby reducing the circumferential strength of the double-wall corrugated pipe; when the speed is too low, the residence time of the high-rigidity integral material will be prolonged, and there may be a risk of degradation due to increased temperature.

[0064] The back pressure should be controlled within the above range to avoid shear overheating of the high-rigidity integral material caused by excessive back pressure, which may cause decomposition of the coupling agent of the modified mica powder.

[0065] 3) The traction speed is 8~12m / min, the cooling method adopts synchronous water cooling of the inner and outer walls, the cooling water temperature is 15~25℃, and the vacuum degree in the shaping sleeve is 60~70kPa.

[0066] By controlling the pulling speed within the above range and matching the low screw speed with the slow pulling speed, sufficient support for the melt is ensured during corrugation formation, especially at the peaks and troughs. Excessive pulling speeds can easily lead to thinning or fracture of the double-wall corrugated pipe wall. Excessive pulling speeds can also affect the corrugation morphology, resulting in uneven corrugation due to the accumulation of high-rigidity, monolithic material.

[0067] By selecting the above cooling method, the inner and outer walls are water-cooled synchronously, and the cooling air volume is increased, especially in the inner layer of the double-wall corrugated tube, to avoid uneven cooling caused by the poor thermal conductivity of the modified mica powder, resulting in defects such as the core not being cooled thoroughly.

[0068] By controlling the vacuum degree of the shaping sleeve within the above range, the fit between the high-rigidity integral material and the shaping sleeve can be enhanced, compensating for insufficient molding caused by decreased fluidity.

[0069] In a second aspect, the present invention provides a mica-reinforced and modified high-rigidity double-wall corrugated pipe, which is prepared by the preparation method of any one of the aforementioned embodiments.

[0070] In a third aspect, the present invention provides an application of a double-wall corrugated pipe according to the aforementioned embodiment in a drainage or sewage pipe system.

[0071] Example 1 Please refer to Figure 1 This embodiment provides a method for preparing a mica-reinforced and modified high-rigidity double-wall corrugated pipe, comprising the following steps: S01. Preparation of modified mica powder Polyethylene glycol and coupling agent KH550 were mixed in a mass ratio of 3:1, and then added into an ethanol-water mixed solvent (the volume ratio of ethanol to water was 4:1) and mixed evenly to prepare a mixed solution.

[0072] The total concentration of polyethylene glycol and coupling agent KH550 in the mixed solution was 5 wt %.

[0073] Mica powder with a diameter-to-thickness ratio of 120:1 was added to a mixed solution of mica powder and nano-montmorillonite at a mass ratio of 9:1, with the total mass of mica powder and nano-montmorillonite to the volume of the mixed solution being 80g:1mL. Ultrasonic dispersion modification was then performed at a temperature of 50°C, a duration of 60 minutes, a frequency of 25kHz, and a power of 500W.

[0074] After the modification is completed, the solid is separated and vacuum dried to obtain modified mica powder.

[0075] S02. Preparation of high-rigidity integrated material High-density polyethylene, maleic anhydride grafted polyethylene, and the modified mica powder obtained in step S01 were added to a twin-screw extruder in a mass ratio of 70:5:20 for melt blending to prepare a high-rigidity integral material.

[0076] The twin-screw extruder's two screws rotate in the same direction, with an aspect ratio of 36:1. The screw surface features a micro-pit array structure, with each pit measuring 100 μm in diameter and 30 μm deep, and a 300 μm spacing between adjacent pits. The screws are divided into a feeding section, a melting section, a mixing section, and a homogenizing section, along the feed-to-discharge path. The homogenizing section is followed by the extruder's die head.

[0077] In this embodiment, the diameter of the screw is 150 mm, the pitch of the feeding section is 180 mm, and the depth of the screw groove is 30 mm.

[0078] The melting section has a gradual pitch, transitioning from 180mm to 150mm from the feeding section to the mixing section. The melting section accounts for 40% of the total screw length. Shallow-toothed kneading blocks serve as threaded elements in the melting section. These blocks are staggered at 45° and 15mm thick. Each screw has three sets of these blocks, with the spacing between adjacent blocks being 300mm.

[0079] The pitch of the mixing and homogenizing sections is 150mm, and the screw groove is 30mm. The mixing section accounts for 40% of the total screw length. The mixing and homogenizing sections are equipped with reverse conveying blocks and barrier threads. The reverse conveying blocks are staggered at 65°, and each screw is equipped with two sets of reverse conveying blocks.

[0080] The length-to-diameter ratio of the head flow channel of the twin-screw extruder is 10:1, and the convergence angle is equal to 30°.

[0081] The mixing parameters of high-density polyethylene, maleic anhydride grafted polyethylene and modified mica in the twin-screw extruder include: a rotation speed of 70 rpm, a temperature of the feeding section of 150° C., a temperature of the melting section of 180° C., a temperature of the mixing section of 190° C., a temperature of the homogenizing section of 190° C., and a temperature of the die head of 180° C.

[0082] The compression ratio of the mixed melt of high-density polyethylene, maleic anhydride grafted polyethylene and modified mica in the melting section is 2.2, and the vacuum degree in the mixing section is 0.08 MPa.

[0083] S03, Double-wall corrugated pipe forming process The high-rigidity integral material obtained in step S02 is extruded using a single-screw extruder.

[0084] The temperature of the feeding section of the single-screw extruder is 185°C, the compression section is 210°C, the metering section is 210°C, the head is 210°C, and the die is 205°C; the speed of the single-screw extruder is 20rpm, and the back pressure is 0.5MPa; the traction speed of the high-rigidity integral material is 8m / min, and the cooling method adopts synchronous water cooling of the inner and outer walls. The cooling water temperature is 15°C, and the vacuum degree in the shaping sleeve is 60kPa.

[0085] Example 2 This embodiment provides a method for preparing a mica-reinforced and modified high-rigidity double-wall corrugated pipe. The specific steps are similar to those in Example 1, with the only difference being that the mass ratio of high-density polyethylene, maleic anhydride grafted polyethylene, and modified mica powder is 70:5:30.

[0086] Example 3 This embodiment provides a method for preparing a mica-reinforced and modified high-rigidity double-wall corrugated pipe. The specific steps are similar to those in Example 1, with the only difference being that the mass ratio of high-density polyethylene, maleic anhydride grafted polyethylene, and modified mica powder is 70:2:30.

[0087] Comparative Example 1 This comparative example provides a method for preparing a double-wall corrugated pipe. The specific steps are similar to those in Example 1, except that no modified mica powder and compatibilizer are added, and high-density polyethylene is directly extruded and formed according to step S03.

[0088] Comparative Example 2 This comparative example provides a method for preparing a double-wall corrugated pipe. The specific steps are similar to those of Example 2, except that modified talc powder is used instead of modified mica powder. The preparation method of the modified talc powder includes: mixing talc powder with a coupling agent KH550 at a ratio of 80g:1mL, followed by high-temperature drying at 120°C for 2 hours.

[0089] Comparative Example 3 This comparative example provides a method for preparing a double-wall corrugated pipe. The specific steps are similar to those in Example 1, except that the mica powder is not modified, and the raw materials in step S02 are high-density polyethylene and unmodified mica powder in a mass ratio of 70:30.

[0090] Comparative Example 4 This comparative example provides a method for preparing a double-wall corrugated pipe. The specific steps are similar to those in Example 2, with the only difference being that the aspect ratio of the screw of the twin-screw extruder in step S02 is 40:1.

[0091] Comparative Example 5 This comparative example provides a method for preparing a double-wall corrugated pipe. The specific steps are similar to those in Example 2, with the only difference being that the rotation speed of the twin-screw extruder in step S02 is 100 rpm.

[0092] Comparative Example 6 This comparative example provides a method for preparing a double-wall corrugated pipe. The specific steps are similar to those of Example 2, except that step S03 is different, as follows: The high-rigidity integral material obtained in step S02 is extruded using a single-screw extruder.

[0093] The temperature of the feeding section of the single-screw extruder is 180°C, the compression section is 190°C, the metering section is 200°C, the head is 200°C, and the die is 195°C; the speed of the single-screw extruder is 50rpm, and the back pressure is 1.0MPa; the traction speed of the high-rigidity integral material is 15m / min, and the cooling method adopts synchronous water cooling of the inner and outer walls. The cooling water temperature is 20°C, and the vacuum degree in the shaping sleeve is 60kPa.

[0094] Comparative Example 7 This comparative example provides a method for preparing a mica-reinforced, modified, high-rigidity double-wall corrugated pipe. The specific steps are similar to those of Example 2, with the only difference being that in step S02, the high-rigidity integral material is mixed using a single-screw extruder, and the parameters of the single screw are the same as those of Example 1. Specifically, the number of screws in the twin-screw extruder of Example 1 is simply adjusted to one, and the screw structure and operating parameters of the single-screw extruder (such as speed, temperature, vacuum degree, and compression ratio) are the same as those of Example 1.

[0095] Test Example 1 The double-wall corrugated pipes prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were subjected to performance tests according to GB / T19472.1-2019, and the results shown in Table 1 were obtained.

[0096] Table 1 Performance of double-wall corrugated pipe

[0097] As shown in Table 1, the double-wall corrugated pipes prepared using the methods provided in the examples of the present invention exhibit high ring stiffness, excellent impact resistance, good ring flexibility, and a suitable density, achieving both light weight and excellent mechanical properties. Example 2, with its high mica content, exhibits higher ring stiffness and slightly reduced impact resistance, but still meets national standards and exhibits excellent overall performance. Example 3 reduces the compatibilizer content compared to Example 2. Comparative Example 1 uses pure high-density polyethylene to prepare double-wall corrugated pipes, which have low ring stiffness and are easily damaged during use, making it difficult to meet usage requirements; Comparative Example 2 uses modified talcum powder to replace modified mica powder, which has low ring stiffness and poor overall performance; the mica powder in Comparative Example 3 is not modified, and no compatibilizer is added, its TIR is high, and the ring stiffness is low. The unmodified and uncompatibilized mica powder has poor dispersion in the HDPE substrate, resulting in poor performance; Comparative Examples 4 and 5 adjusted the parameters of the twin-screw extruder, and their ring stiffness was lower than that of Example 2, and their TIR was higher than that of Example 2. The overall performance of the obtained double-wall corrugated pipes was poor, mainly because the high aspect ratio and high rotation speed would destroy the microstructure of the mica; Comparative Example 6 adjusted the molding process parameters of the double-wall corrugated pipe, and the TIR was unqualified. The performance of the obtained double-wall corrugated pipes was poor, mainly because the molding effect was poor and the size of the pipes was uneven. In comparative example 7, a single-screw extruder is used in step S02, which has low ring stiffness and poor overall performance. The reason is that the shear rate of the single screw is unevenly distributed, a high shear zone is easily formed in the melting section, and the mixing ability is weak, which easily leads to problems such as mica structure destruction and uneven dispersion.

[0098] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a mica-reinforced and modified high-rigidity double-wall corrugated pipe, characterized in that: The method comprises mixing modified mica powder, high-density polyethylene and a compatibilizer to prepare a high-rigidity integral material, and then subjecting the high-rigidity integral material to melt blending and extrusion molding; The preparation of the modified mica powder comprises the steps of using a coupling agent to perform ultrasonic mixing modification on the mica powder.

2. The preparation method according to claim 1, characterized in that The preparation method of the modified mica powder comprises: mixing a dispersant, a coupling agent and a solvent to prepare a mixed solution, dispersing the mica powder in the mixed solution to perform ultrasonic mixing modification, and drying the solid in the mixed solution after modification; And / or, the coupling agent includes one or more of a silane coupling agent, a titanate coupling agent or an aluminate coupling agent; and / or, the mass ratio of the dispersant to the coupling agent is 1 to 3:1; and / or, the total concentration of the dispersant and the coupling agent in the solvent is 2-5 wt %; And / or, the solvent comprises an ethanol-water mixed solvent, wherein the volume ratio of ethanol to water in the ethanol-water mixed solvent is 3 to 5:1; and / or, the dispersant comprises at least one of polyethylene glycol or polyvinyl pyrrolidone; And / or, the mica powder has an aspect ratio greater than or equal to 80; And / or, the process of modifying the mica powder in the mixed solution further comprises adding nano-montmorillonite to the mixed solution; And / or, the mass ratio of the nano-montmorillonite to the mica powder is 1:8-10; And / or, during the modification of the mica powder in the mixed solution, the mass volume ratio of the solid material to the mixed solution is 60-80 g:1 mL; And / or, during the modification process, the ultrasonic temperature is 40-50° C., the ultrasonic time is 30-60 min, the ultrasonic frequency is 20-30 kHz, and the ultrasonic power is 300-500 W.

3. The preparation method according to claim 1, characterized in that The preparation of the high-rigidity integral material comprises mixing a mixed melt of the modified mica powder, the high-density polyethylene and the compatibilizer using a twin-screw extruder.

4. The preparation method according to claim 3, characterized in that The mixed melt is mixed using a twin-screw extruder, and the two screws of the twin-screw extruder rotate in the same direction; And / or, the screw parameters of the twin-screw extruder include at least one of the following 1) to 8); 1) The aspect ratio of the screw is 28-36:1, the length of the melting section accounts for 30-40% of the total length of the screw, and the length of the mixing section accounts for 40-50% of the total length of the screw; 2) The pitch of the feeding section of the screw is 1.2 to 1.5 times the screw diameter, and the screw groove depth is 0.15 to 0.2 times the screw diameter; 3) The pitch of the melting section of the screw is a gradual pitch, and the pitch transitions from 1.15 to 1.25 times the screw diameter to 0.95 to 1.05 times the screw diameter along the direction from the feeding section to the mixing section; 4) The melting section of the screw is further provided with shallow toothed kneading blocks as thread elements. The staggered angle of the shallow toothed kneading blocks is 30-45 degrees and the thickness is 10-15 mm. Each screw is provided with 2-3 groups of shallow toothed kneading blocks, and the spacing between two adjacent shallow toothed kneading blocks is 2-3 times the screw diameter. 5) The pitch of the mixing section and the homogenizing section of the screw is 0.95 to 1.05 times the screw diameter, and the screw groove is 0.2 to 0.25 times the screw diameter; 6) The screws of the mixing section and the homogenizing section are provided with reverse conveying blocks and / or barrier-type threads; the reverse conveying blocks are staggered at an angle of 55-65°, and each screw is provided with 1-2 sets of the reverse conveying blocks; 7) The surface of the screw has a micro-pit array structure, each micro-pit has a diameter of 50-100 μm, a depth of 20-30 μm, and a spacing between two adjacent micro-pits of 200-300 μm; 8) The length-to-diameter ratio of the die flow channel of the twin-screw extruder is 8-10:1, and the convergence angle is less than or equal to 30°.

5. The preparation method according to claim 4, characterized in that The compression ratio of the mixed melt in the melting section is 1.8 to 2.

2.

6. The preparation method according to claim 4, characterized in that The parameters of the mixing process of the modified mica powder, the high-density polyethylene and the compatibilizer include at least one of the following 1) to 3); 1) The speed of the twin-screw extruder is 50~80rpm; 2) The temperature of the feeding section is 140-150°C, the temperature of the melting section is 170-180°C, the temperature of the mixing section is 180-190°C, the temperature of the homogenizing section is 190-200°C, and the temperature of the die head is 180-190°C; 3) The vacuum degree of the mixing section is 0.05~0.08MPa.

7. The preparation method according to claim 1, characterized in that The mass ratio of the modified mica powder, the high-density polyethylene and the compatibilizer is: 20-80:40-80:2-10; And / or, the compatibilizer includes any one of maleic anhydride grafted polyethylene or methacrylic acid grafted polyethylene.

8. The preparation method according to claim 1, characterized in that The melt blending extrusion molding includes extrusion using a single screw extruder, and the parameters of the single screw extruder extrusion process include at least one of the following 1) to 3); 1) The temperature of the feeding section is 185~195℃, the compression section is 200~210℃, the metering section is 210~220℃, the die is 210~220℃, and the die is 205~215℃; 2) The speed of the single screw extruder is 20-35 rpm, and the back pressure is 0.3-0.8 MPa; 3) The traction speed is 8~12m / min, the cooling method adopts synchronous water cooling of the inner and outer walls, the cooling water temperature is 15~25℃, and the vacuum degree in the shaping sleeve is 60~70kPa.

9. A mica reinforced and modified high-rigidity double-wall corrugated pipe, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the double-wall corrugated pipe according to claim 9 in a drainage or sewage pipe system.

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