High-impact-resistance high-molecular polymer underground communication pipeline and preparation method thereof

Abstract

The invention relates to the technical field of high-molecular composite materials, and discloses a high-impact-resistance high-molecular polymer underground communication pipeline and a preparation method of the high-impact-resistance high-molecular polymer underground communication pipeline. 28 to 32 parts of polyvinyl chloride; 7 to 9 parts of a core-shell type nano toughening agent; 4 to 6 parts of amino modified nano montmorillonite; 0.4 to 0.6 part of dicumyl peroxide; 1.2 to 1.8 parts of gamma-aminopropyltriethoxysilane (gamma-aminopropyltriethoxysilane); the method comprises the following steps: pretreating raw materials, dynamically vulcanizing and blending, carrying out gradient co-extrusion molding on an outer pressure-resistant layer, a middle impact-resistant layer and an inner conductive layer, regulating and controlling the orientation of montmorillonite through an axial stretching flow field, and then carrying out vacuum cooling, fiber winding enhancement and laser grooving sealing treatment. According to the invention, a multi-layer composite structure is constructed through dynamic vulcanization and gradient co-extrusion processes, and high impact resistance, long-acting sealing and durability of the pipe are realized in combination with montmorillonite directional arrangement, laser grooving sealing and glass fiber reinforcement technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, in particular to a high-impact polymer underground communication pipeline and a preparation method thereof. Background Art

[0002] Underground communication pipelines are subject to multiple loads, including soil pressure, mechanical impact, and hot and humid corrosion, for a long time. Traditional polymer pipes are prone to brittle fracture due to their insufficient impact resistance. This is especially true in cold regions, where freeze-thaw cycles or vehicle dynamic loads can cause microcracks to expand within the material, exacerbating the risk of leakage. Existing technologies often use single polymer blends or simple fiber reinforcements. Poor interfacial compatibility leads to phase separation, resulting in low interlayer peel strength and difficulty balancing the requirements of rigid support and toughness and energy dissipation. Furthermore, the homogeneous pipe wall structure produced by conventional extrusion processes cannot accommodate functional zoning design features, such as outer layer compression resistance, middle layer buffering, and inner layer conductivity, leading to localized failure of the pipeline under complex operating conditions.

[0003] Currently, pipe sealing mostly relies on flange connection or adhesive filling. The former weakens the strength of the pipe body due to drilling and is prone to rust, while the latter is prone to joint slippage due to the limitation of interfacial adhesion. In particular, the sealing reliability is significantly reduced under the stress of thermal expansion and contraction. In addition, the conventional cooling and shaping process makes it difficult to synchronously control the orientation distribution of the montmorillonite reinforcement phase and the network integrity of the conductive filler. During long-term service, the material will experience problems such as increased creep rate and resistivity fluctuations due to molecular chain relaxation or filler agglomeration, which restricts the durability of underground pipelines and signal transmission stability. The tightening of environmental regulations also places higher demands on the recyclability of pipes. The existing technology uses a large amount of irreversibly cross-linked thermosetting resins or heavy metal stabilizers, which increases the environmental disposal burden of abandoned pipelines.

[0004] Therefore, the present invention proposes a high-impact polymer underground communication pipeline and a preparation method thereof to solve the deficiencies of the prior art. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a high-impact polymer underground communication pipeline and its preparation method, which solves the problems of fracture and leakage, sealing failure and poor durability of underground communication pipes caused by insufficient impact resistance, weak interface bonding, single function and easy creep during long-term service.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a high-impact polymer underground communication pipeline, the pipeline comprising the following components in parts by mass:

[0007] High-density polyethylene: 55-65 parts;

[0008] Polyvinyl chloride: 28-32 parts;

[0009] Core-shell nano toughening agent: 7-9 parts;

[0010] Amino-modified nano-montmorillonite: 4-6 parts;

[0011] Dicumyl peroxide: 0.4-0.6 parts;

[0012] γ-Aminopropyltriethoxysilane: 1.2-1.8 parts.

[0013] Using high-density polyethylene (HDPE) as the continuous phase and polyvinyl chloride (PVC) as the dispersed phase, a dynamic vulcanization reaction is initiated by dicumyl peroxide (DCP), simultaneously achieving crosslinking of the HDPE and plasticization of the PVC in the shear field of a twin-screw extruder. During this process, the crosslinked network of the HDPE molecular chains forms a chemically interpenetrating structure with the PVC microdomains. This crosslinking point restricts the slippage of the PVC molecular chains, thereby improving the material's creep resistance. Furthermore, the dynamic vulcanization process avoids the interfacial debonding defects caused by phase separation in traditional blends, achieving a synergistic enhancement of mechanical properties.

[0014] The core-shell nanotoughener consists of a silicone rubber core and an epoxy-grafted acrylate shell. The elastic deformation of the core dissipates impact energy, while the epoxy groups in the shell undergo nucleophilic substitution with the -Cl groups in the PVC molecular chain, forming covalent bonds. This design creates a chemical bridging network at the HDPE / PVC interface, enhancing interfacial bonding strength while avoiding the negative impact of excessive toughening agent addition on material rigidity.

[0015] The amino-modified nano-montmorillonite was prepared via an ion exchange reaction between sodium montmorillonite and hexadecyltrimethylammonium bromide. First, the interlayer metal ions were replaced in an alkaline aqueous solution at 60°C to expand the interlayer spacing. Subsequently, the nano-montmorillonite was treated with silanization with γ-aminopropyltriethoxysilane (KH550). The hydrolysis-generated silanol groups condensed with the hydroxyl groups on the montmorillonite surface to form covalent bonds, while the terminal amino groups were distributed in a targeted manner on the surface of the montmorillonite. This modification process increased the interlayer spacing of the montmorillonite from 1.2 nm to over 2.8 nm. The amino groups significantly improved the interfacial compatibility with the polymer matrix and served as peroxide activation sites during dynamic vulcanization, promoting the anchoring and growth of the crosslinked network between the montmorillonite layers.

[0016] After activation with a silane coupling agent, the amino-modified nano-montmorillonite intercalates with the -CH2- groups of the HDPE molecular chains through hydrogen bonding. During subsequent axial tensile flow, the montmorillonite flakes align along the pipe's axis, forming a reinforced structure similar to a "rebar skeleton." This axial orientation of the montmorillonite flakes not only enhances the pipe's hoop stiffness but also absorbs impact energy through interlamellar slip, achieving a balanced balance between rigidity and toughness.

[0017] Preferably, the high-density polyethylene has a bimodal distribution and a density of 0.953-0.958 g / cm3 ; The degree of polymerization of the polyvinyl chloride is 1250-1350.

[0018] Preferably, the core layer of the core-shell nano toughener is methyl vinyl silicone rubber with a core particle size of 80-120 nm, and the shell layer is acrylic acid ester grafted with glycidyl methacrylate with a shell thickness of 10-20 nm.

[0019] Preferably, the interlayer spacing of the amino-modified nano-montmorillonite is ≥3.0 nm and the cation exchange capacity is 95-105 mmol / 100 g; the purity of the dicumyl peroxide is ≥98% and the active oxygen content is ≥5.6%; the amino content of the γ-aminopropyltriethoxysilane is ≥0.7 mmol / g and the purity is ≥97%.

[0020] The present invention also provides a method for preparing a high-impact polymer underground communication pipeline, the method comprising the following steps:

[0021] S1, drying high-density polyethylene, premixing polyvinyl chloride with an organotin stabilizer, and performing silane coupling activation on the amino-modified nano-montmorillonite, wherein the silane coupling activation uses γ-aminopropyltriethoxysilane;

[0022] S2, melt-blending the pretreated high-density polyethylene, polyvinyl chloride, core-shell nano toughening agent, activated nano-montmorillonite and dicumyl peroxide, and extruding the mixture through a twin-screw extruder for dynamic vulcanization reaction;

[0023] S3, forming the dynamically vulcanized alloy melt into a composite pipe having an outer pressure-resistant layer, a middle impact-resistant layer, and an inner conductive layer through a gradient co-extrusion die, and controlling the orientation of the nano-montmorillonite through an axial stretching flow field;

[0024] S4. The pipe is vacuum sized and cooled, reinforced by glass fiber winding, and sealed by laser grooving at the end.

[0025] Preferably, the step S1 includes:

[0026] The high-density polyethylene is dried at 75-85° C. for 3.5-4.5 hours;

[0027] When the polyvinyl chloride is premixed, 0.7-0.9 parts of an organic tin stabilizer and 0.3-0.5 parts of calcium stearate are added, the premixing temperature is 45-55° C., and the mixing time is 8-10 minutes;

[0028] In the silane coupling activation treatment of the amino-modified nano-montmorillonite, the addition amount of γ-aminopropyltriethoxysilane is 25-35% of the mass of the nano-montmorillonite, the activation temperature is 105-115° C., and the activation time is 12-18 minutes.

[0029] Preferably, the step S2 includes:

[0030] The melt blending temperature is 180-190°C and the mixing time is 8-12 minutes;

[0031] The screw speed of the twin-screw extruder is 350-450 rpm, and the extrusion temperature is controlled in five zones: zone 1: 175-180°C, zone 2: 185-190°C, zone 3: 190-195°C, zone 4: 195-200°C, and zone 5: 200-205°C.

[0032] The amount of dicumyl peroxide added in the dynamic vulcanization reaction is 1.2-1.8% of the mass of polyvinyl chloride, and the reaction time is 2.5-3.5 minutes;

[0033] The mass ratio of the core-shell nano toughening agent to the amino-modified nano montmorillonite is 1.5:1-2.5:1;

[0034] The extrusion pressure is 12-16 MPa.

[0035] Preferably, the structural parameters of the gradient co-extrusion die in step S3 are:

[0036] The compression ratio of the outer pressure-resistant layer is 2.5:1-3.5:1 and the flow channel inclination angle is 25-35°. The compression ratio of the middle impact-resistant layer is 1.8:1-2.2:1 and the flow channel inclination angle is 15-25°. The compression ratio of the inner conductive layer is 3.0:1-4.0:1 and the flow channel inclination angle is 40-50°.

[0037] The content of activated nano-montmorillonite in the outer compression layer is 8-10% and the addition amount of nitrogen micro-foaming agent is 0.2-0.4%, the content of core-shell nano-toughening agent in the middle impact-resistant layer is 10-12%, and the content of conductive carbon black in the inner conductive layer is 14-16%;

[0038] The thickness ratio of the outer layer, the middle layer and the inner layer of the composite pipe is 1:0.6-0.8:0.4-0.6.

[0039] The outer pressure-resistant layer, the middle impact-resistant layer and the inner conductive layer are formed simultaneously through a gradient co-extrusion die head:

[0040] Outer compression layer: High-content nano-montmorillonite and nitrogen micro-foam structure form a "rigid skeleton-porous energy absorption" composite system. The axial orientation of the montmorillonite enhances the compressive strength, and the micro-foam pores dissipate external impact energy through collapse and deformation;

[0041] Middle impact-resistant layer: enriched with core-shell nano-tougheners, which utilize the dual mechanism of energy dissipation and interface bonding of the core-shell structure to prevent crack propagation;

[0042] Inner conductive layer: Conductive carbon black forms a three-dimensional conductive network in the HDPE matrix, which achieves static dissipation through electron tunneling effect and avoids communication signal interference.

[0043] Preferably, the control parameters of the axial stretching flow field in step S3 are:

[0044] Die convergence angle 18-22°, melt drawing rate 300-400s -1 , stretching temperature 175-185 ° C; the axial orientation angle of the nano-montmorillonite layer is ≤ 5°, the aspect ratio of the montmorillonite layer is ≥ 50: 1 and the orientation degree is ≥ 85%;

[0045] The length of the outlet shaping section of the gradient co-extrusion die head is 2.0-2.5 times the outer diameter of the pipe and the shaping pressure is 8-12 MPa.

[0046] An axial stretching flow field is applied in the convergent section of the gradient coextrusion die. Through the coupling of the melt stretching rate and the temperature field, the nano-montmorillonite flakes are induced to align along the axial direction of the tube. The high degree of orientation of the montmorillonite flakes (≥85%) causes them to undergo an energy-dissipating "sheet slip-reorientation" mechanism under hoop stress, significantly improving the tube's bending resistance. Furthermore, the oriented montmorillonite flakes serve as a pre-formed framework for fiber winding reinforcement, enhancing the interfacial bonding strength between the subsequent glass fiber and the matrix.

[0047] Preferably, the step S4 includes:

[0048] During the vacuum sizing cooling, the outer layer cooling rate is 50-60°C / min and the inner layer cooling rate is 20-30°C / min, and the sizing pressure is 0.3-0.5MPa;

[0049] In the glass fiber winding reinforcement, the fiber tape tension is 7.5-8.5N and the winding angle is 45-55°, the number of winding layers is 3-5 layers, the heat setting temperature after winding is 135-145°C and the holding time is 8-12 minutes;

[0050] During the laser grooving and sealing treatment of the port, the grooving depth is 0.25-0.35 mm, the groove width is 0.15-0.25 mm and the grooving rate is 120-150 mm / s. The coating amount of the hot melt adhesive after grooving is 0.8-1.2 g / m, and the curing temperature of the hot melt adhesive is 105-115°C.

[0051] A differentiated cooling strategy employs rapid cooling of the outer layer and slow cooling of the inner layer. Rapid cooling of the outer layer instantly freezes the montmorillonite's oriented structure, preventing orientation rebound caused by molecular chain relaxation. Slow cooling of the inner layer reduces internal stress in the conductive carbon black network caused by thermal contraction, preventing microcracks in the conductive layer. This gradient cooling process ensures the dimensional stability of the pipe and the integrity of the functional layer.

[0052] Glass fiber is wound at a 45-55° helix angle, achieving an optimal ratio of hoop and axial load distribution (60-70% of the load is centered). During the heat setting process, the fiber wrap forms a chemical bond with the pipe matrix. This prestressed state offsets external load fluctuations during service and improves long-term deformation resistance.

[0053] Laser grooving creates micron-scale grooves at the ends of the pipe, increasing the contact area of ​​the joint through a mechanical interlocking effect. During the curing process, the hot-melt adhesive penetrates the grooves, forming a dual sealing interface with the groove walls through both chemical bonding and physical anchoring. This design overcomes the limitations of traditional adhesive seals, which rely on surface bonding, and significantly improves the joint's resistance to leakage and slippage.

[0054] The present invention provides a high-impact polymer underground communication pipeline and a preparation method thereof. It has the following beneficial effects:

[0055] This invention constructs an HDPE / PVC interpenetrating network structure through a dynamic vulcanization reaction. Combined with the elastic energy dissipation and interfacial chemical bonding mechanism of a core-shell toughening agent, this effectively disperses stress under external impact loads, preventing brittle fracture. During the preparation process, an axial tensile flow field induces oriented alignment of the montmorillonite flakes, forming a biomimetic reinforced skeleton that synergistically enhances creep resistance and ensures controllable long-term deformation in complex underground stress environments.

[0056] 2. This invention overcomes the performance limitations of traditional pipes limited by single materials through the zoned flow channel design of the gradient co-extrusion die head and the coordinated molding of the outer high-rigidity montmorillonite reinforcement layer, the middle toughening buffer layer, and the inner conductive layer. Dynamic vulcanization and linked control of extrusion process parameters ensure close interface bonding between the functional layers, while simultaneously meeting the multiple requirements of compression resistance, impact resistance, and electromagnetic shielding.

[0057] 3. This invention utilizes a gradient cooling process to rapidly lock the montmorillonite's orientation in the outer layer, while slowly cooling the inner layer reduces stress within the conductive layer, thereby inhibiting the propagation of microcracks caused by temperature fluctuations. The optimized design of the glass fiber winding angle and prestress distribution further blocks the crack propagation path, ensuring the pipeline maintains long-term structural integrity in harsh geological conditions such as humidity, heat, acidity, and alkalinity.

[0058] 4. This invention utilizes a composite sealing technology combining laser grooving and hot-melt adhesive coating, achieving efficient sealing of pipe joints through the synergistic effect of mechanical interlocking and chemical bonding. This process avoids the weakening of pipe walls associated with traditional flange connections while simplifying on-site construction processes, making it particularly suitable for rapid deployment of underground pipe networks in confined spaces.

[0059] 5. This invention utilizes a recyclable HDPE / PVC substrate in its composition design, combined with a dynamic vulcanization process, to achieve high-value recycling of waste plastics. No heavy metal stabilizers are required during the preparation process, and the use of montmorillonite intercalation reduces polymer usage, improving performance while reducing raw material costs and environmental risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a flow chart of the preparation method of the present invention;

[0061] Figure 2 Schematic diagram of the pipeline of the present invention. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0063] See also Figure 1 -read Figure 2 :

[0064] Example 1:

[0065] Formula composition (mass parts): 60 parts of high-density polyethylene, 30 parts of polyvinyl chloride, 8 parts of core-shell nano toughener, 5 parts of amino-modified nano montmorillonite, 0.5 parts of dicumyl peroxide, and 1.5 parts of γ-aminopropyltriethoxysilane.

[0066] The preparation steps are as follows:

[0067] Raw material pretreatment (S1):

[0068] High-density polyethylene was treated in a drying oven at 80°C for 4 hours;

[0069] Polyvinyl chloride was premixed with 0.8 parts of organotin stabilizer and 0.4 parts of calcium stearate in a high-speed mixer at 50°C for 9 minutes;

[0070] The amino-modified nano-montmorillonite was activated with 30% by mass of γ-aminopropyltriethoxysilane (i.e., 1.5 parts of silane) at 110°C for 15 minutes.

[0071] Dynamic vulcanization reaction extrusion (S2):

[0072] The pretreated raw materials were melt blended at 185°C for 10 minutes;

[0073] Twin-screw extruder parameters: screw speed 400 rpm, five-zone temperatures are 178°C, 188°C, 193°C, 198°C, and 203°C, and extrusion pressure is 14 MPa;

[0074] Dynamic vulcanization reaction conditions: DCP addition amount is 1.5% (i.e. 0.45 parts) of PVC mass, reaction time is 3 minutes; the mass ratio of core-shell toughening agent to montmorillonite is 2:1.

[0075] Gradient coextrusion (S3):

[0076] Die head parameters: outer layer compression ratio 3:1, flow channel inclination 30°, middle layer compression ratio 2:1, flow channel inclination 20°, inner layer compression ratio 3.5:1, flow channel inclination 45°;

[0077] Functional layer components: the outer layer contains 9% montmorillonite + 0.3% nitrogen foaming agent, the middle layer contains 11% toughening agent, and the inner layer contains 15% conductive carbon black;

[0078] Pipe thickness ratio 1:0.7:0.5; stretching flow field control: convergence angle 20°, stretching rate 350s -1 , temperature 180℃, montmorillonite orientation degree 88%.

[0079] Post-processing (S4):

[0080] Vacuum sizing cooling: outer layer cooling rate 55℃ / min, inner layer 25℃ / min, sizing pressure 0.4MPa;

[0081] Glass fiber winding: tension 8.0N, winding angle 50°, number of layers 4, heat setting temperature 140℃, holding temperature for 10 minutes;

[0082] Laser grooving: groove depth 0.30 mm, groove width 0.20 mm, grooving rate 135 mm / s, hot melt adhesive coating amount 1.0 g / m, curing temperature 110°C.

[0083] Example 2:

[0084] Formula composition (mass parts): 55 parts of high-density polyethylene, 28 parts of polyvinyl chloride, 7 parts of core-shell nano toughener, 4 parts of amino-modified nano montmorillonite, 0.4 parts of dicumyl peroxide, and 1.2 parts of γ-aminopropyltriethoxysilane.

[0085] The preparation steps are as follows:

[0086] Raw material pretreatment (S1):

[0087] High-density polyethylene was dried at 75°C for 3.5 hours;

[0088] Polyvinyl chloride was premixed with 0.7 parts of organotin stabilizer and 0.3 parts of calcium stearate at 45°C for 8 minutes;

[0089] Montmorillonite activation: Silane addition amount is 25% (i.e. 1.0 part), activation temperature is 105℃ and lasts for 12 minutes.

[0090] Dynamic vulcanization reaction extrusion (S2):

[0091] Melt blending temperature 180 ° C, time 8 minutes;

[0092] The twin-screw speed is 350 rpm, the five-zone temperatures are 175°C, 185°C, 190°C, 195°C, and 200°C, and the extrusion pressure is 12 MPa;

[0093] The DCP addition amount was 1.2% (0.336 parts), the reaction time was 2.5 minutes, and the core-shell toughening agent / montmorillonite ratio was 1.5:1.

[0094] Gradient coextrusion (S3):

[0095] The outer layer has a compression ratio of 2.5:1 and an inclination of 25°; the middle layer has a compression ratio of 1.8:1 and an inclination of 15°; the inner layer has a compression ratio of 3:1 and an inclination of 40°;

[0096] Outer layer: 8% montmorillonite + 0.2% foaming agent, middle layer: 10% toughening agent, inner layer: 14% carbon black; thickness ratio: 1:0.6:0.4;

[0097] Tensile flow field: convergence angle 18°, rate 300s -1 , temperature 175℃, montmorillonite orientation degree 85%.

[0098] Post-processing (S4):

[0099] The outer layer is cooled at 50℃ / min, the inner layer at 20℃ / min, and the sizing pressure is 0.3MPa;

[0100] Fiber tension 7.5N, winding angle 45°, 3 layers, heat setting 135℃ for 8 minutes;

[0101] The groove depth is 0.25 mm, the groove width is 0.15 mm, the speed is 120 mm / s, the hot melt adhesive is 0.8 g / m, and the curing temperature is 105°C.

[0102] Example 3:

[0103] Formula composition (mass parts): 65 parts of high-density polyethylene, 32 parts of polyvinyl chloride, 9 parts of core-shell nano toughener, 6 parts of amino-modified nano montmorillonite, 0.6 parts of dicumyl peroxide, and 1.8 parts of γ-aminopropyltriethoxysilane.

[0104] The preparation steps are as follows:

[0105] Raw material pretreatment (S1):

[0106] High-density polyethylene was dried at 85°C for 4.5 hours;

[0107] Polyvinyl chloride was premixed with 0.9 parts of organotin stabilizer and 0.5 parts of calcium stearate at 55°C for 10 minutes;

[0108] Montmorillonite activation: 35% silane addition (i.e. 2.1 parts), activation temperature 115°C for 18 minutes.

[0109] Dynamic vulcanization reaction extrusion (S2):

[0110] Melt blending temperature 190 ° C, time 12 minutes;

[0111] The twin-screw speed was 450 rpm, the five-zone temperatures were 180°C, 190°C, 195°C, 200°C, and 205°C, and the extrusion pressure was 16 MPa.

[0112] The DCP addition amount was 1.8% (0.576 parts), the reaction time was 3.5 minutes, and the core-shell toughening agent / montmorillonite ratio was 2.5:1.

[0113] Gradient coextrusion (S3):

[0114] The outer layer has a compression ratio of 3.5:1 and an inclination angle of 35°; the middle layer has a compression ratio of 2.2:1 and an inclination angle of 25°; the inner layer has a compression ratio of 4:1 and an inclination angle of 50°;

[0115] Outer layer: montmorillonite 10% + foaming agent 0.4%, middle layer: toughening agent 12%, inner layer: carbon black 16%; thickness ratio: 1:0.8:0.6;

[0116] Tensile flow field: Convergence angle 22°, rate 400s -1 , temperature 185℃, montmorillonite orientation degree 90%.

[0117] Post-processing (S4):

[0118] The outer layer is cooled at 60℃ / min, the inner layer at 30℃ / min, and the sizing pressure is 0.5MPa;

[0119] Fiber tension 8.5N, winding angle 55°, number of layers 5, heat setting 145℃ for 12 minutes;

[0120] The groove depth is 0.35 mm, the groove width is 0.25 mm, the speed is 150 mm / s, the hot melt adhesive is 1.2 g / m, and the curing temperature is 115°C.

[0121] Comparative Example 1:

[0122] Compared with Example 1, the difference is that dicumyl peroxide (DCP) is not added in step S2, and dynamic vulcanization reaction is not performed during the twin-screw extrusion process. The other preparation conditions are the same as those in Example 1.

[0123] Comparative Example 2:

[0124] Compared with Example 1, the difference is that the core-shell nano toughening agent is replaced by an equal amount of ordinary styrene-butadiene rubber (without core-shell structure and without epoxy group), and the other preparation conditions are the same as those in Example 1.

[0125] Comparative Example 3:

[0126] Compared with Example 1, the difference is that the amino-modified nano-montmorillonite is replaced by unmodified sodium-montmorillonite, and the silane coupling activation treatment is not performed in step S1. The other preparation conditions are the same as those in Example 1.

[0127] Comparative Example 4:

[0128] Compared with Example 1, the difference is that a common single-layer extrusion die head (compression ratio 2.5:1, flow channel inclination angle 25°) is used in step S3, and the outer layer, middle layer and inner layer structures are not distinguished. The other preparation conditions are the same as those in Example 1.

[0129] Comparative Example 5:

[0130] Compared with Example 1, the difference is that no axial stretching flow field is applied in step S3 (ie, there is no die head convergence angle and stretching rate control), and the other preparation conditions are the same as those in Example 1.

[0131] Comparative Example 6:

[0132] Compared with Example 1, the difference is that the mass ratio of the core-shell nano toughening agent to the amino-modified nano montmorillonite is 1:1 (2:1 in Example 1), and the other preparation conditions are the same as in Example 1.

[0133] Comparative Example 7:

[0134] Compared with Example 1, the difference is that during vacuum sizing cooling in step S4, the outer layer and the inner layer adopt the same cooling rate (40°C / min), and the other preparation conditions are the same as those in Example 1.

[0135] Test Example 1: Interface bonding and dynamic vulcanization effect experiment

[0136] Experimental purpose: To verify the key role of dynamic vulcanization reaction, core-shell toughening agent structure and toughening agent / montmorillonite ratio on the material interface bonding and mechanical properties.

[0137] The test samples are as follows:

[0138] Sample No. Sample type Description of key differences 1# Example 1 Completely innovative process preparation 2# Comparative Example 1 (without DCP) No DCP added, no dynamic vulcanization reaction 3# Comparative Example 2 (Ordinary Styrene-Butadiene Rubber) The core-shell toughening agent is replaced by ordinary styrene-butadiene rubber 4# Comparative Example 6 (mass ratio 1:1) Toughener / montmorillonite mass ratio 1:1 (2:1 in Example 1)

[0139] The experimental steps are as follows:

[0140] Sample preparation:

[0141] Each sample was injection molded into a standard test specimen (tensile specimen: GB / T-1040-2006-Type-1A; impact specimen: GB / T-1843-2008-80×10×4 mm notched specimen).

[0142] Interlayer peeling specimen: Cut the cross section of the gradient structure pipe and bond the outer layer and the middle layer to form a peeling surface (bonding area 25×10mm).

[0143] Tensile strength test:

[0144] Equipment: Universal material testing machine (50kN range, 0.5% accuracy);

[0145] Conditions: tensile rate 50 mm / min, room temperature 23 ± 2 °C;

[0146] Data recording: Take the average value of 5 samples and retain 1 decimal place.

[0147] Notched impact strength test:

[0148] Equipment: Pendulum impact tester (energy 7.5 J, span 60 mm);

[0149] Conditions: notch depth 2mm, impact speed 3.8m / s;

[0150] Data recording: Take the mean of 10 samples after removing outliers and retain the integer.

[0151] Interlayer peel strength test:

[0152] Equipment: Universal material testing machine (5kN range, 100mm clamp spacing);

[0153] Conditions: peeling angle 180°, rate 100 mm / min;

[0154] Data recording: Convert the peak peel force into unit width strength (N / mm) and retain two decimal places.

[0155] The experimental data are shown in Table 1:

[0156] Table 1: Test Example 1 - Interface Bonding and Dynamic Vulcanization Effect Test Data

[0157] Sample No. Tensile strength (MPa) <![CDATA[Izod impact strength (kJ / m 2 )]]> Interlayer peel strength (N / mm) 1# 38.7 69 8.35 2# 24.3 31 3.12 3# 29.5 45 5.8 4# 32.8 53 6.94

[0158] Test Case 1 Experimental Summary:

[0159] The dynamic vulcanization process triggers the chemical crosslinking of high-density polyethylene and polyvinyl chloride by dicumyl peroxide to form an interpenetrating network structure, which significantly improves the material interface bonding force. When the dynamic vulcanization reaction was not carried out in Comparative Example 1, the tensile strength and interlayer peeling strength decreased by 37.2% and 62.6% respectively, verifying the anchoring effect of the HDPE crosslinking network and the PVC micro-region during the dynamic vulcanization process. Its mechanism of limiting the slippage of the molecular chain effectively inhibits the interface peeling. The interpenetrating network further cooperates with the chemical bonding of the epoxy group of the core-shell nano toughener and the PVC molecular chain. Experimental data show that after Comparative Example 2 uses ordinary rubber to replace the core-shell toughener, the notched impact strength is reduced by 34.8%, indicating that the synergistic mechanism of the elastic core layer energy dissipation and shell chemical bridging of the core-shell structure is crucial to the improvement of impact performance.

[0160] The optimized synergistic ratio of amino-modified montmorillonite intercalation and core-shell toughening agents further enhanced material properties. In Comparative Example 6, the imbalance of the toughening agent to montmorillonite mass ratio (1:1) resulted in a 15.2% decrease in tensile strength, demonstrating that a 1.5:1-2.5:1 ratio achieves a balance of stiffness and toughness through the synergistic effect of toughening agent enrichment at the interface and enhanced dispersion of the montmorillonite flakes. Amino modification and silane activation of the montmorillonite enhance its compatibility with the polymer matrix. In Comparative Example 3, the unmodified montmorillonite exhibited limited reinforcement due to insufficient intercalation and flake agglomeration, further demonstrating the key role of modified montmorillonite in interfacial strengthening.

[0161] Comprehensive experimental data show that the interpenetrating network constructed by dynamic vulcanization reaction, the chemical bridging of core-shell toughening agents and the coordinated design of montmorillonite intercalation-orientation are the core innovative paths for improving material interface bonding and mechanical properties.

[0162] Test Example 2: Functional structure and process correlation experiment

[0163] Experimental purpose: To verify the synergistic effect of gradient co-extrusion structure design, montmorillonite modification process and axial tensile flow field on the rigidity, conductivity and mechanical properties of the pipe.

[0164] The test samples are as follows:

[0165] Sample No. Sample type Description of key differences 1# Example 1 Completely innovative process preparation 2# Comparative Example 3 (unmodified montmorillonite) Using unmodified sodium montmorillonite and not silane activated 3# Comparative Example 4 (single-layer structure) Ordinary single-layer extrusion structure, no functional partition 4# Comparative Example 5 (no stretching flow field) Without axial tensile flow, montmorillonite is randomly distributed.

[0166] The experimental steps are as follows:

[0167] Sample preparation:

[0168] Ring stiffness test: Cut the pipe to a length of 300mm, and make sure both ends are smooth and free of burrs (according to GB / T-9647);

[0169] Surface resistivity test: Cut the inner conductive layer into 50×50mm square specimens, clean the surface with ethanol and then dry;

[0170] Three-point bending test: injection molded standard specimens (80×10×4mm), 5 specimens per group.

[0171] Ring stiffness test:

[0172] Equipment: Ring stiffness testing machine (50kN range, 200mm plate diameter);

[0173] Conditions: compression rate 5 mm / min, compression amount 3% pipe diameter, record the maximum load;

[0174] Data calculation: Ring stiffness = 0.0186 × load (N) / deformation (mm), retain one decimal place.

[0175] Surface resistivity test:

[0176] Equipment: High resistance meter (test voltage 100V, range 1×10 3 ~1×10 12 Ω);

[0177] Conditions: room temperature 23±2℃, humidity 50±5%, electrode spacing 50mm;

[0178] Data recording: Take the median of three measurements and express it in scientific notation.

[0179] Three-point bending strength test:

[0180] Equipment: Universal material testing machine (span 64mm, indenter radius 5mm);

[0181] Conditions: Loading rate 2 mm / min, record the breaking load;

[0182] Data calculation: Bending strength = 3 × load × span / (2 × width × thickness 2 ), retain the integer.

[0183] The experimental data are shown in Table 2:

[0184] Table 2: Test Example 2 - Functional Structure and Process Correlation Test Data

[0185] Sample No. <![CDATA[Ring stiffness (kN / m 2 )]]> Surface resistivity (Ω) Three-point bending strength (MPa) 1# 14.3 <![CDATA[8.2×10 2 ]]> 82 2# 9.7 <![CDATA[3.6×10 4 ]]> 64 3# 6.5 <![CDATA[2.1×10 11 ]]> 58 4# 11.2 <![CDATA[7.9×10 2 ]]> 70

[0186] Test Case 2 Experimental Summary:

[0187] The zoning structure design of the gradient co-extrusion die head forms a rigidity-enhanced honeycomb-shaped compression-resistant layer through the synergistic effect of the high-compression ratio flow channel in the outer layer and the montmorillonite micro-foaming. When the single-layer structure is used in Example 4, the ring stiffness decreases by 54.5%, verifying the directional regulation of mechanical bearing capacity by functional zoning. The axial orientation of the outer layer of montmorillonite and the nitrogen foaming holes form a "skeleton-pore" composite system, which dissipates energy through the dual mechanisms of hole collapse and layer slip under compression load, while the core-shell toughening agent enriched in the middle impact-resistant layer resists the fracture propagation path through the elastic core layer deformation. The two work together to make the ring stiffness of Example 1 reach 14.3kN / m 2 , which is significantly higher than the single-layer homogeneous structure of Comparative Example 4.

[0188] The silane activation treatment of amino-modified montmorillonite and the control of axial stretching flow field are the key to achieving high orientation of the sheets. When unmodified montmorillonite was used in Comparative Example 3, the ring stiffness decreased by 32.2% and the surface resistivity increased to 10 due to insufficient intercalation between the layers and the aggregation of the sheets. 4 Ω-level performance demonstrates that the modified montmorillonite not only enhances rigidity but also maintains the continuity of the carbon black network in the conductive layer by improving dispersion. In Example 1, the montmorillonite flakes were aligned axially with an aspect ratio of ≥50:1 under a tensile flow field, forming a fiber-like reinforced structure. The three-point bending strength increased by 14.6% compared to Comparative Example 5 (without a tensile flow field). This demonstrates that the oriented flakes absorb energy through slip reorientation under bending stress, breaking through the strength bottleneck of traditional randomly filled composite materials.

[0189] The synergistic effect of the high compression ratio flow channel design (3.5:1) of the conductive layer and the gradient cooling process ensures the uniform dispersion of the carbon black network under high shear of the melt. The single-layer structure of Comparative Example 4 lacks a dedicated flow channel for the conductive layer, resulting in low carbon black dispersion and a surface resistivity increase to the insulating level (10 11 Ω), while in Example 1, the inner layer flow channel is inclined at 45° and the slow cooling process (20-30℃ / min) is used to reduce the carbon black agglomeration cracks, so that the resistivity is stabilized at 10 2 Ω level.

[0190] Test Example 3: Long-term service performance experiment

[0191] Experimental purpose: To verify the effects of gradient cooling process, glass fiber winding angle and laser groove sealing treatment on the long-term dimensional stability, sealing reliability and aging resistance of the pipe.

[0192] The test samples are as follows:

[0193] Sample No. Sample type Description of key differences 1# Example 1 Completely innovative process preparation 2# Comparative Example 7 (Uniform Cooling) The cooling rate of the outer and inner layers is 40℃ / min 3# Comparative Example 8 (without laser grooving) The pipe ends are not laser grooved and are directly coated with hot melt adhesive

[0194] The experimental steps are as follows:

[0195] Creep rate test:

[0196] Sample preparation: Cut the pipe into a length of 200 mm, seal both ends, and apply a constant hoop stress (6 MPa);

[0197] Equipment: Constant temperature and humidity creep testing machine (temperature 23±1℃, humidity 50±5%);

[0198] Conditions: Continuous loading for 1000 hours, with radial deformation recorded every 24 hours;

[0199] Data calculation: Creep rate = (final deformation - initial deformation) / time (mm / h), retain 3 decimal places.

[0200] Sealing joint slip force test:

[0201] Sample preparation: Laser groove the ends of two pipes (or not) and then glue them together with hot melt adhesive. Let it cure for 24 hours.

[0202] Equipment: Universal material testing machine (150mm clamp spacing, 20kN range);

[0203] Conditions: Axial tensile rate 10 mm / min, record the maximum load when the joint is detached;

[0204] Data recording: The slip force (kN) is the average of three tests, with one decimal place retained.

[0205] Aging resistance test:

[0206] Sample preparation: Cut the pipe to make impact test strips (GB / T-1843), 5 per group;

[0207] Equipment: UV aging box (wavelength 340nm, irradiation intensity 0.5W / m 2 , temperature 60℃);

[0208] Conditions: Continuous aging for 500 hours, sampling every 100 hours to test notched impact strength;

[0209] Data recording: Impact strength retention rate after aging = (strength after aging / initial strength) × 100%, retain the integer.

[0210] The experimental data are shown in Table 3:

[0211] Table 3: Test Example 3 - Long-term service performance test data

[0212] Sample No. Creep rate (mm / h) Slip force (kN) Impact strength retention rate after aging (%) 1# 0.0137 4.8 89 2# 0.0254 4.5 76 3# 0.0142 2.1 88

[0213] Test Case 3 Experimental Summary:

[0214] The gradient cooling process locks the montmorillonite layer orientation through rapid cooling of the outer layer (55°C / min), forming a stable molecular chain anchoring structure. In contrast, the uniform cooling employed in Comparative Example 7 resulted in premature solidification of the outer layer, leading to increased molecular chain relaxation and an 85.4% increase in creep rate. Slow cooling of the inner layer (25°C / min) reduces thermal stress cracking in the carbon black network of the conductive layer. Combined with the prestressed distribution of the glass fiber winding (50° winding angle), Example 1 maintains 89% impact strength retention under long-term loads, significantly slowing the progression of interfacial embrittlement caused by UV aging.

[0215] The synergistic sealing mechanism of laser grooving and hot-melt adhesive coating, through the mechanical interlocking structure formed by the groove depth (0.30mm), allows the adhesive to penetrate the groove bottom and sidewalls, achieving a three-dimensional bond between the adhesive layer and the substrate. In Comparative Example 3, where no grooves were used, relying solely on the physical adhesion of the adhesive to the smooth surface, the slip force decreased by 56.3%, demonstrating that the groove structure effectively resists joint slip by increasing the contact area and providing a stress-dissipating path. When cured at 110°C, the hot-melt adhesive partially eutectics with the polymer in the groove inner wall, forming a dual chemical-mechanical bond, further ensuring a long-lasting seal.

[0216] The matching design of the glass fiber winding angle (50°) and the heat setting temperature (140°C) achieves an optimal balance between the circumferential and axial stress distribution of the fibers in the tube. In Example 1, the fiber layer experiences a moderate shrinkage differential with the matrix during the heat setting process, forming a pre-compressive stress layer that inhibits microcrack propagation. In contrast, in Comparative Example 7, uniform cooling leads to concentrated thermal stress in the inner layer, resulting in a drop in impact retention to 76% after 500 hours of UV aging. This demonstrates that the synergistic effect of gradient cooling and the fiber winding angle effectively blocks the chain reaction of performance degradation triggered by environmental factors.

[0217] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-impact polymer underground communication pipeline, characterized in that: The pipeline comprises the following components in parts by mass: High-density polyethylene: 55-65 parts; Polyvinyl chloride: 28-32 parts; Core-shell nano toughening agent: 7-9 parts; Amino-modified nano-montmorillonite: 4-6 parts; Dicumyl peroxide: 0.4-0.6 parts; γ-Aminopropyltriethoxysilane: 1.2-1.8 parts.

2. The high-impact polymer underground communication pipeline according to claim 1, characterized in that: The high-density polyethylene has a bimodal distribution and a density of 0.953-0.958 g / cm 3 ; The degree of polymerization of the polyvinyl chloride is 1250-1350.

3. The high-impact polymer underground communication pipeline according to claim 1, characterized in that: The core layer of the core-shell nano toughener is methyl vinyl silicone rubber with a core particle size of 80-120 nm, and the shell layer is acrylic acid ester grafted with glycidyl methacrylate with a shell thickness of 10-20 nm.

4. The high-impact polymer underground communication pipeline according to claim 1, characterized in that: The interlayer spacing of the amino-modified nano-montmorillonite is ≥3.0 nm and the cation exchange capacity is 95-105 mmol / 100 g; the purity of the dicumyl peroxide is ≥98% and the active oxygen content is ≥5.6%; the amino content of the γ-aminopropyltriethoxysilane is ≥0.7 mmol / g and the purity is ≥97%.

5. A method for preparing a high-impact polymer underground communication pipeline, applied to a high-impact polymer underground communication pipeline according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1, drying high-density polyethylene, premixing polyvinyl chloride with an organotin stabilizer, and performing silane coupling activation on the amino-modified nano-montmorillonite, wherein the silane coupling activation uses γ-aminopropyltriethoxysilane; S2, melt-blending the pretreated high-density polyethylene, polyvinyl chloride, core-shell nano toughening agent, activated nano-montmorillonite and dicumyl peroxide, and extruding the mixture through a twin-screw extruder for dynamic vulcanization reaction; S3, forming the dynamically vulcanized alloy melt into a composite pipe having an outer pressure-resistant layer, a middle impact-resistant layer, and an inner conductive layer through a gradient co-extrusion die, and controlling the orientation of the nano-montmorillonite through an axial stretching flow field; S4. The pipe is vacuum sized and cooled, reinforced by glass fiber winding, and sealed by laser grooving at the end.

6. The method for preparing a high-impact polymer underground communication pipeline according to claim 5, characterized in that: The step S1 comprises: The high-density polyethylene is dried at 75-85° C. for 3.5-4.5 hours; When the polyvinyl chloride is premixed, 0.7-0.9 parts of an organic tin stabilizer and 0.3-0.5 parts of calcium stearate are added, the premixing temperature is 45-55° C., and the mixing time is 8-10 minutes; In the silane coupling activation treatment of the amino-modified nano-montmorillonite, the addition amount of γ-aminopropyltriethoxysilane is 25-35% of the mass of the nano-montmorillonite, the activation temperature is 105-115° C., and the activation time is 12-18 minutes.

7. The method for preparing a high-impact polymer underground communication pipeline according to claim 5, characterized in that: The step S2 comprises: The melt blending temperature is 180-190°C and the mixing time is 8-12 minutes; The screw speed of the twin-screw extruder is 350-450 rpm, and the extrusion temperature is controlled in five zones: zone 1: 175-180°C, zone 2: 185-190°C, zone 3: 190-195°C, zone 4: 195-200°C, and zone 5: 200-205°C. The amount of dicumyl peroxide added in the dynamic vulcanization reaction is 1.2-1.8% of the mass of polyvinyl chloride, and the reaction time is 2.5-3.5 minutes; The mass ratio of the core-shell nano toughening agent to the amino-modified nano montmorillonite is 1.5:1-2.5:1; The extrusion pressure is 12-16 MPa.

8. The method for preparing a high-impact polymer underground communication pipeline according to claim 5, characterized in that: The structural parameters of the gradient co-extrusion die in step S3 are: The compression ratio of the outer pressure-resistant layer is 2.5:1-3.5:1 and the flow channel inclination angle is 25-35°. The compression ratio of the middle impact-resistant layer is 1.8:1-2.2:1 and the flow channel inclination angle is 15-25°. The compression ratio of the inner conductive layer is 3.0:1-4.0:1 and the flow channel inclination angle is 40-50°. The content of activated nano-montmorillonite in the outer compression layer is 8-10% and the addition amount of nitrogen micro-foaming agent is 0.2-0.4%, the content of core-shell nano-toughening agent in the middle impact-resistant layer is 10-12%, and the content of conductive carbon black in the inner conductive layer is 14-16%; The thickness ratio of the outer layer, the middle layer and the inner layer of the composite pipe is 1:0.6-0.8:0.4-0.

6.

9. The method for preparing a high-impact polymer underground communication pipeline according to claim 5, characterized in that: The control parameters of the axial stretching flow field in step S3 are: Die convergence angle 18-22°, melt drawing rate 300-400s -1 , stretching temperature 175-185 ° C; the axial orientation angle of the nano-montmorillonite layer is ≤ 5°, the aspect ratio of the montmorillonite layer is ≥ 50: 1 and the orientation degree is ≥ 85%; The length of the outlet shaping section of the gradient co-extrusion die head is 2.0-2.5 times the outer diameter of the pipe and the shaping pressure is 8-12 MPa.

10. The method for preparing a high-impact polymer underground communication pipeline according to claim 5, characterized in that: The step S4 comprises: During the vacuum sizing cooling, the outer layer cooling rate is 50-60°C / min and the inner layer cooling rate is 20-30°C / min, and the sizing pressure is 0.3-0.5MPa; In the glass fiber winding reinforcement, the fiber tape tension is 7.5-8.5N and the winding angle is 45-55°, the number of winding layers is 3-5 layers, the heat setting temperature after winding is 135-145°C and the holding time is 8-12 minutes; During the laser grooving and sealing treatment of the port, the grooving depth is 0.25-0.35 mm, the groove width is 0.15-0.25 mm and the grooving rate is 120-150 mm / s. The coating amount of the hot melt adhesive after grooving is 0.8-1.2 g / m, and the curing temperature of the hot melt adhesive is 105-115°C.

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