High-toughness MPP cable protection pipe and preparation method thereof

Abstract

The invention discloses a high-toughness MPP cable protection tube and a preparation method thereof, and relates to the technical field of cable protection tubes, and the protection tube is prepared from the following raw materials in parts by mass through melt blending and extrusion molding: 70-85 parts of modified polypropylene matrix resin, 10-20 parts of a composite toughening system, 3-8 parts of a reinforced fiber in-situ fiber forming component and 1-5 parts of a functional additive. A shell layer of a core shell is an intercalation network of nano-scale organic montmorillonite and hyperbranched polyesteramide, and a core layer is a maleic anhydride grafted hydrogenated styrene-butadiene block copolymer, so that the nano-scale organic montmorillonite and hyperbranched polyesteramide intercalation network in core shell particles inhibits crack propagation; and the maleic anhydride grafted hydrogenated styrene-butadiene block copolymer has the functions of improving the interfacial compatibility and improving the low-temperature toughness.

Description

Technical Field

[0001] This invention relates to the field of cable protection pipe technology, specifically to a high-toughness MPP cable protection pipe and its preparation method. Background Technology

[0002] Traditional PVC pipes have a temperature resistance limit of 70-90℃. However, in high-voltage cable operation, conductor temperatures can reach over 90℃, and during short circuits exceeding 250℃, they easily soften and deform, leading to pipe deformation or cable damage due to pressure. While concrete and steel pipes are heat-resistant, they suffer from brittleness and corrosion, making them unsuitable for complex environments. Ordinary PVC pipes have a ring stiffness of only 2-4 kN / m², insufficient to withstand the multiple pressures of soil layers, vehicle traffic, and construction in urban underground pipe networks, and are prone to deformation due to uneven settlement. Rigid pipes such as concrete pipes require numerous joints when turning or bypassing obstacles, increasing leakage risk and extending construction time. Furthermore, existing high-toughness MPP cable protection pipes cannot suppress crack propagation and have poor interfacial compatibility, reducing low-temperature toughness.

[0003] The existing high-toughness MPP cable protection pipes have the following drawbacks: 1. Patent document CN120709892A discloses a high-toughness MPP cable protection pipe and its preparation method, "including a protection pipe body and an inner tube layer, the outer surface of the inner tube layer is extruded with a filling core layer, the outer surface of the filling core layer is spirally wound with multiple flexible metal wires, the outer surface of the filling core layer is extruded with an outer tube layer, the inner wall of one end of the protection pipe body is provided with an internal thread, the outer wall of the other end of the protection pipe body is provided with an external thread, and the external thread is corresponding to the internal thread, the outer diameter of the external thread is the same as the inner diameter of the internal thread, the inner and outer walls of the two ends of the MPP cable protection pipe are provided with threads in opposite directions, the two cable protection pipes are spliced ​​by the threaded connection at both ends, no auxiliary equipment is needed for installation, improving the splicing efficiency of the cable protection pipe, the spliced ​​cable protection pipe can be quickly disassembled, which is convenient for subsequent inspection of the cable inside the cable protection pipe, and improves the use effect of the cable protection pipe." However, the existing high-toughness MPP cable protection pipe cannot suppress crack propagation and has poor interface compatibility, which reduces low-temperature toughness. Summary of the Invention

[0004] The purpose of this invention is to provide a high-toughness MPP cable protection pipe and its preparation method, so as to solve the technical problems mentioned in the background art that the high-toughness MPP cable protection pipe cannot suppress crack propagation and has poor interfacial compatibility, which reduces low-temperature toughness.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-toughness MPP cable protection pipe, wherein the protection pipe is prepared by melt blending and extrusion molding of the following raw materials in parts by weight: 70-85 parts of modified polypropylene matrix resin, 10-20 parts of composite toughening system, 3-8 parts of in-situ fiber-forming component of reinforcing fiber, and 1-5 parts of functional additives, wherein the melt flow rate of the modified polypropylene matrix resin is 0.5-1.5 g / 10 min at 230℃ and 2.16 kg, and the isotacticity of the modified polypropylene matrix resin is greater than or equal to 95%, and the composite toughening system comprises the following materials in parts by weight: maleic anhydride grafted with hydrogen... The composition includes 5-12 parts of styrene-butadiene block copolymer, 3-8 parts of nano-sized organomontmorillonite, and 2-5 parts of hyperbranched polyesteramide. The interlayer spacing of the nano-sized organomontmorillonite is greater than or equal to 2.5 nm, and the terminal hydroxyl functionalization of the hyperbranched polyesteramide is 8-16. The in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melt temperature difference greater than or equal to 30 °C, and the ratio of polyvinyl alcohol to polyphenylene sulfide is 1:2 to 2:1. The functional additives are an antioxidant complex, a light stabilizer, and a lubricant, ethylene bis-stearamide. The antioxidant complex is an antioxidant 1010 / 168 complex, and the stabilizer is light stabilizer 944.

[0006] Preferably, the modified polypropylene matrix resin is a propylene-ethylene block copolymer, wherein the ethylene segment content is 8-15 wt%, and 5-10% of butyl rubber microparticles, accounting for 5% of the total resin content, are premixed by dynamic vulcanization technology, and the particle size of the butyl rubber microparticles is less than or equal to 1 μm.

[0007] Preferably, in the composite toughening system, the grafting rate of the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 0.8-1.5%, and the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is pre-assembled with nano-sized organomontmorillonite and hyperbranched polyesteramide in a mass ratio of 3-4:1-2:1 to form core-shell structured composite particles. The shell layer is an intercalation network of nano-sized organomontmorillonite and hyperbranched polyesteramide, and the core layer is the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer.

[0008] Preferably, the in-situ fiber-forming component of the reinforcing fiber is induced by a biaxial tensile field during the extrusion process, and polyvinyl alcohol and polyphenylene sulfide form microfibers with a diameter of 50~200nm and an aspect ratio of ≥50, and the microfibers are oriented along the axial direction of the tube with an orientation degree of ≥85%.

[0009] Preferably, the ring stiffness of the protective tube is greater than or equal to SN12, the drop hammer impact strength of the protective tube is greater than or equal to 15kJ / m² in an environment of ~30℃, and the heat deformation temperature of the protective tube is greater than or equal to 125℃ in an environment of 0.45MPa.

[0010] Preferably, the method for preparing the protective tube includes the following steps: Step 1, Premixing Modification: The components of the composite toughening system are premixed in a high-speed mixer at 80~100℃ for 10~15min to form core-shell composite particles; Step 2, Matrix Activation: The modified polypropylene matrix resin and the in-situ fiber-forming component of the reinforcing fiber are added to the main feed port of the twin-screw extruder and melted and plasticized at the working temperature of 160~180℃ of the twin-screw extruder to form a molten matrix; Step 3, Gradient Blending: The core-shell composite particles obtained in Step 1 are injected into a twin-screw extruder through a side feed port and blended with the molten matrix at 180~210℃ to form a blended melt. The screw speed of the twin-screw extruder is 200~400 rpm, and the shear rate is greater than or equal to 500 s. -1 ; Step 4, In-situ fiber formation and orientation: After the blended melt is extruded through the die of a twin-screw extruder, it immediately enters a biaxial stretching device and is formed under the conditions of longitudinal stretching ratio of 3~5:1 and transverse stretching ratio of 2~3:1. The cooling and setting temperature is 40~60℃. Step 5, Post-processing: The protective tube is sized and cut to obtain the finished product.

[0011] Preferably, the gradient blending step 3 adopts a three-zone temperature control design: the first zone is 180 ± 5℃ to allow the polyvinyl alcohol and polyphenylene sulfide to melt and disperse; the second zone is 195 ± 5℃ to trigger the interface reaction between maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, nano-sized organomontmorillonite, and hyperbranched polyesteramide core-shell particles and the matrix; the third zone is 205 ± 5℃ to complete the construction of the dynamic crosslinking network.

[0012] Preferably, the biaxial stretching device is a composite mechanism of air-expanded radial expansion and tracked axial traction, wherein the radial expansion air pressure is 0.8~1.2MPa and the axial traction speed ratio is 3.0~4.5; in step 4, during the cooling and shaping process, an alternating electromagnetic field is applied, the frequency of the alternating electromagnetic field is 50~100Hz, and the intensity of the alternating electromagnetic field is 0.5~1T, to induce the nano-sized organic montmorillonite sheets to be radially oriented along the pipe wall.

[0013] Preferably, the protective tube has a composite structure of a micro-foamed layer and a dense skin layer. The micro-foamed layer has a density of 0.6~0.8 g / cm³ and a pore diameter of less than or equal to 50 μm. The dense skin layer has a thickness of 20~30% of the wall thickness. 0.2~0.5% of nano-calcium carbonate nucleating agent is added to the micro-foamed layer, and the foaming agent is a compound of endothermic azodicarbonamide and exothermic 4,4'-oxobisbenzenesulfonyl hydrazine, with a compounding ratio of 1:1~1:2.

[0014] Preferably, the outer surface of the protective tube is provided with a spiral corrugated reinforcement structure, with a peak height of 4-6 mm, a wave pitch of 8-12 mm, and a corrugated cross section that is trapezoidal with an inclination angle of 45-60°. Conductive carbon fiber yarns are embedded at the bottom of the corrugations, with a diameter of 7-10 μm and a resistivity of less than or equal to 10 μm. -3 The shielding tube is coated with nano-silica and fluorosilicone resin hydrophobic coatings, with a thickness of 10~20μm, a contact angle of ≥150°, and a roll-off angle of ≤5°. The inner wall of the protective tube is coated with nano-silica and fluorosilicone resin hydrophobic coatings, with a contact angle of ≥150° and a roll-off angle of ≤5°.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes a composite toughening system with a maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer grafting rate of 1.2%. The maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is pre-assembled with nano-sized organomontmorillonite and hyperbranched polyesteramide in a mass ratio of 3~4:1~2:1 to form core-shell structured composite particles. The shell layer is an intercalation network of nano-sized organomontmorillonite and hyperbranched polyesteramide, and the core layer is maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer. This achieves the functions of inhibiting crack propagation by the intercalation network of nano-sized organomontmorillonite and hyperbranched polyesteramide in the core-shell particles, improving interfacial compatibility, and enhancing low-temperature toughness by the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer. 2. This invention employs a three-zone temperature control design in the gradient blending step 3: Zone 1 is 180 ± 5°C to melt and disperse polyvinyl alcohol and polyphenylene sulfide; Zone 2 is 195 ± 5°C to trigger the interface reaction between maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, nano-sized organomontmorillonite, and hyperbranched polyesteramide core-shell particles and the matrix; Zone 3 is 205 ± 5°C to complete the construction of a dynamic cross-linked network. The biaxial stretching device is a composite mechanism of air-expanded radial expansion and tracked axial traction, wherein the radial expansion air pressure is 1.0 MPa and the axial traction speed ratio is 3.0~4.5; in step 4, during the cooling and shaping process, the alternating electromagnetic field is eliminated, realizing the formation of microfibers with a diameter of 150 nm and an aspect ratio of 60 between polyvinyl alcohol and polyphenylene sulfide, with an axial orientation degree of 90%, thus enabling the nanofibers to be directionally reinforced. 3. In this invention, a three-zone temperature control design is adopted in the gradient blending step 3: the first zone is 180 ± 5℃ to melt and disperse polyvinyl alcohol and polyphenylene sulfide; the second zone is 195 ± 5℃ to trigger the interface reaction between maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, nano-sized organomontmorillonite, and hyperbranched polyesteramide core-shell particles and the matrix; the third zone is 205 ± 5℃ to complete the construction of a dynamic cross-linked network. The biaxial stretching device is a composite mechanism of air-expanded radial expansion and tracked axial traction, wherein the radial expansion air pressure is 1.0MPa and the axial traction speed ratio is 3.0~4.5; in step 4, during the cooling and shaping process, an alternating electromagnetic field is applied with a frequency of 80Hz and an intensity of 0.8T to induce the nano-sized organomontmorillonite sheets to be radially oriented along the pipe wall. This achieves the function of the sheet-oriented arrangement blocking water molecule diffusion, improving water resistance, and solving the circumferential strength deficiency. 4. This invention utilizes a composite structure in the pipe wall of the protective tube, which consists of a micro-foamed layer and a dense skin layer. The micro-foamed layer has a density of 0.7 g / cm³ and a pore diameter of ≤50 μm. The dense skin layer accounts for 25% of the wall thickness. 0.3% of nano-calcium carbonate nucleating agent is added to the micro-foamed layer, and the foaming agent is a compound of endothermic azodicarbonamide and exothermic 4,4'-oxobisbenzenesulfonyl hydrazine in a ratio of 1:1.5. This achieves reduced pipe density, making it lightweight and energy-saving, while the pore structure reduces thermal conductivity, protecting the cable from external temperature differences and improving thermal insulation performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the comparison of the low-temperature toughness properties of the present invention; Figure 2 This is a schematic diagram illustrating the comparison of tensile strength properties of the present invention; Figure 3 This is a comparative illustration of the water-resistant performance of the present invention; Figure 4 This is a comparative illustration of the thermal insulation performance of the present invention; Figure 5 This is a schematic diagram illustrating the comparative performance of the corrugated compressive strength of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The test conditions for the comparative examples and embodiments were as follows: Impact strength was tested according to ISO 179-1:2010 using a notched beam simple support test. The specimen size was 80×10×4 mm, the notch depth was 2 mm, and the test temperature was -30℃ / 23℃. The equipment used was an Instron 5967 universal testing machine and a ZBC-4B impact testing machine. Heat distortion temperature was measured according to GB / T 1634.2-2019, with a load of 0.45 MPa and a heating rate of 120℃ / h, at which point the deformation reached 0.25 mm. Ring stiffness was tested according to GB / T 19472.1-2019 using a three-point loading test. The pipe diameter was Φ110 mm, the compression rate was 2 mm / min, and the SN grade was calculated using the formula S = (0.0186×F) / δ, where F is the load and δ is the deformation; tensile strength was simulated during underground laying, with axial pressure applied until the pipe buckled, and the maximum load was recorded; the equipment used was an XJ-832 pipe ring stiffness testing machine; pipe sections were obtained after wall thinning and subjected to liquid nitrogen brittle fracture, and the morphology and orientation of PVA / PPS microfibers were observed using a Hitachi SU8010 field emission electron microscope; electromagnetic shielding effectiveness was tested according to IEEE 299-2006 using a vector network analyzer (Keysight N5224B) in the 1 GHz band (SE = 10log). 10 (P t / P o ), P t Incident power, P o Transmitted power; hydrophobicity and abrasion resistance were measured using an OCA20 contact angle meter with 5 μL of deionized water added, measuring the static contact angle and the critical angle at which the substrate tilted to allow the water droplet to roll; coating abrasion resistance was tested according to GB / T 1768-2006 using a rubber wheel abrasion test; lightweighting and thermal insulation were measured using the drainage method (GB / T 1033.1-2008), measuring the ratio of microfoamed layer to skin layer; thermal conductivity was measured using the transient planar heat source method according to ISO 22007-2 standard.

[0019] The comparative example is based on a conventional MPP pipe. The comparative example components are: 85 parts polypropylene homopolymer, 15 parts polyolefin elastomer, and 5 parts calcium carbonate. It is formed by single-screw extrusion. The data are based on GB / T 19472.1 and ISO 179.

[0020] Example 1: Please refer to Figure 1A high-toughness MPP cable protection pipe is disclosed. The pipe is prepared from the following raw materials by melt blending and extrusion molding: 70-85 parts of modified polypropylene matrix resin, 10-20 parts of a composite toughening system, 3-8 parts of in-situ fiber-forming reinforcing fibers, and 1-5 parts of functional additives. The modified polypropylene matrix resin has a melt flow rate of 0.5-1.5 g / 10 min at 230°C and 2.16 kg, and the isotacticity of the modified polypropylene matrix resin is greater than or equal to 95%. The composite toughening system comprises... The mixture comprises the following components by weight: 10 parts maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 5 parts nano-sized organomontmorillonite, and 3 parts hyperbranched polyesteramide. The interlayer spacing of the nano-sized organomontmorillonite is 2.8 nm, and the terminal hydroxyl functionality of the hyperbranched polyesteramide is 12. The in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melt temperature difference of greater than or equal to 30°C, wherein the ratio of polyvinyl alcohol to polyphenylene sulfide is 1:2 to 2:1. The functional additives are an antioxidant complex, a light stabilizer, and a lubricant. The additive is ethylene bis-stearamide, the antioxidant complex is an antioxidant 1010 / 168 complex, the stabilizer is light stabilizer 944, the modified polypropylene matrix resin is a propylene-ethylene block copolymer, wherein the ethylene segment content is 12wt%, and 8% butyl rubber microparticles are premixed in the total resin using dynamic vulcanization technology. The particle size of the butyl rubber microparticles is 0.8μm. In the composite toughening system, the grafting rate of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 1.2%. Butadiene block copolymers, nano-sized organomontmorillonite, and hyperbranched polyesteramide are pre-assembled into core-shell structured composite particles at a mass ratio of 3~4:1~2:1. The shell layer of the core-shell is an intercalation network of nano-sized organomontmorillonite and hyperbranched polyesteramide, and the core layer is maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer. This process enables the nano-sized organomontmorillonite and hyperbranched polyesteramide intercalation network in the core-shell particles to inhibit crack propagation, while the maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer improves interfacial compatibility and enhances low-temperature toughness.

[0021] Comparison table of low-temperature toughness properties.

[0022] Example 2: Please refer to Figure 2A high-toughness MPP cable protection pipe is disclosed. The pipe is prepared by melt blending and extrusion molding of the following raw materials in parts by weight: 70-85 parts modified polypropylene matrix resin, 10-20 parts composite toughening system, 6 parts in-situ fiber-forming component of reinforcing fiber, and 1-5 parts functional additives. The modified polypropylene matrix resin has a melt flow rate of 0.5-1.5 g / 10 min at 230℃ and 2.16 kg, and an isotacticity greater than or equal to 95%. The composite toughening system comprises the following materials in parts by weight: 5-12 parts maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 3-8 parts nano-sized organomontmorillonite, and 2-5 parts hyperbranched polyesteramide. The interlayer spacing of the nano-sized organomontmorillonite is greater than... The diameter is equal to 2.5 nm. The functional degree of the terminal hydroxyl groups of the hyperbranched polyesteramide is 8-16. The in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melt temperature difference of greater than or equal to 30°C. The ratio of polyvinyl alcohol to polyphenylene sulfide is 1.5:1. The functional additives are an antioxidant complex, a light stabilizer, and a lubricant, ethylene bis-stearamide. The antioxidant complex is an antioxidant 1010 / 168 complex. The stabilizer is a light stabilizer 944. During the extrusion process, the in-situ fiber-forming component of the reinforcing fiber is induced by a biaxial stretching field. Polyvinyl alcohol and polyphenylene sulfide form microfibers with a diameter of 50-200 nm and an aspect ratio of greater than or equal to 50. The microfibers are oriented along the axial direction of the tube with an orientation degree of greater than or equal to 85%. The preparation method of this protective tube includes the following steps: Step 1, Premixing Modification: The components of the composite toughening system are premixed in a high-speed mixer at 80~100℃ for 10~15min to form core-shell composite particles; Step 2, Matrix Activation: The modified polypropylene matrix resin and the in-situ fiber-forming component of the reinforcing fiber are added to the main feed port of the twin-screw extruder and melted and plasticized at the working temperature of 160~180℃ of the twin-screw extruder to form a molten matrix; Step 3, Gradient Blending: The core-shell composite particles obtained in Step 1 are injected into a twin-screw extruder through a side feed port and blended with the molten matrix at 180~210℃ to form a blended melt. The screw speed of the twin-screw extruder is 200~400 rpm, and the shear rate is greater than or equal to 500 s. -1 ; Step 4, In-situ fiber formation and orientation: After the blended melt is extruded through the die of a twin-screw extruder, it immediately enters a biaxial stretching device and is formed under the conditions of longitudinal stretching ratio of 4:1 and transverse stretching ratio of 2.5:1. The cooling and setting temperature is 40~60℃. Step 5, Post-processing: The protective tube is sized and cut to obtain the finished product; The gradient blending step 3 employs a three-zone temperature control design: Zone 1 is 180 ± 5°C to melt and disperse polyvinyl alcohol and polyphenylene sulfide; Zone 2 is 195 ± 5°C to trigger the interface reaction between maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, nano-sized organomontmorillonite, and hyperbranched polyesteramide core-shell particles and the matrix; Zone 3 is 205 ± 5°C to complete the construction of a dynamic cross-linked network. The biaxial stretching device is a composite mechanism of air-expanded radial expansion and tracked axial traction, wherein the radial expansion air pressure is 1.0 MPa and the axial traction speed ratio is 3.0~4.5. In step 4, during the cooling and shaping process, the alternating electromagnetic field is eliminated, enabling polyvinyl alcohol and polyphenylene sulfide to form microfibers with a diameter of 150 nm and an aspect ratio of 60, with an axial orientation degree of 90%, thus achieving the function of directional reinforcement of the nanofibers.

[0023] Comparison table of tensile strength properties.

[0024] Example 3, please refer to Figure 3 A high-toughness MPP cable protection pipe is disclosed. The pipe is prepared from the following raw materials by melt blending and extrusion molding: 70-85 parts modified polypropylene matrix resin, 10-20 parts composite toughening system, 6 parts in-situ fiber-forming component, and 1-5 parts functional additives. The modified polypropylene matrix resin has a melt flow rate of 0.5-1.5 g / 10 min at 230°C and 2.16 kg, and an isotacticity greater than or equal to 95%. The composite toughening system comprises the following materials in parts by weight: 5-12 parts maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 6 parts nano-sized organomontmorillonite, and 2-5 parts hyperbranched polyesteramide. The interlayer spacing of the nano-sized organomontmorillonite is greater than... At 2.5 nm, the hyperbranched polyesteramide has a terminal hydroxyl functionality of 8-16. The in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melt temperature difference of ≥30°C, and the ratio of polyvinyl alcohol to polyphenylene sulfide is 1.5:1. The functional additives are an antioxidant complex, a light stabilizer, and a lubricant, ethylene bis-stearamide. The antioxidant complex is an antioxidant 1010 / 168 complex, and the stabilizer is a light stabilizer 944. During the extrusion process, the in-situ fiber-forming component of the reinforcing fiber is induced by a biaxial stretching field, and polyvinyl alcohol and polyphenylene sulfide form microfibers with a diameter of 50-200 nm and an aspect ratio of ≥50. The microfibers are oriented along the axial direction of the tube, and the orientation degree is ≥85%. The preparation method of this protective tube includes the following steps: Step 1, Premixing Modification: The components of the composite toughening system are premixed in a high-speed mixer at 80~100℃ for 10~15min to form core-shell composite particles; Step 2, Matrix Activation: The modified polypropylene matrix resin and the in-situ fiber-forming component of the reinforcing fiber are added to the main feed port of the twin-screw extruder and melted and plasticized at the working temperature of 160~180℃ of the twin-screw extruder to form a molten matrix; Step 3, Gradient Blending: The core-shell composite particles obtained in Step 1 are injected into a twin-screw extruder through a side feed port and blended with the molten matrix at 180~210℃ to form a blended melt. The screw speed of the twin-screw extruder is 200~400 rpm, and the shear rate is greater than or equal to 500 s. -1 ; Step 4, In-situ fiber formation and orientation: After the blended melt is extruded through the die of a twin-screw extruder, it immediately enters a biaxial stretching device and is formed under the conditions of longitudinal stretching ratio of 4:1 and transverse stretching ratio of 2.5:1. The cooling and setting temperature is 40~60℃. Step 5, Post-processing: The protective tube is sized and cut to obtain the finished product; The gradient blending step 3 employs a three-zone temperature control design: Zone 1 is 180 ± 5°C to allow the polyvinyl alcohol and polyphenylene sulfide to melt and disperse; Zone 2 is 195 ± 5°C to trigger the interface reaction between maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, nano-sized organomontmorillonite, and hyperbranched polyesteramide core-shell particles and the matrix; Zone 3 is 205 ± 5°C to complete the construction of a dynamic cross-linked network. The biaxial stretching device is a composite mechanism of air-expanded radial expansion and tracked axial traction, wherein the radial expansion air pressure is 1.0 MPa and the axial traction speed ratio is 3.0~4.5. In step 4, during the cooling and shaping process, an alternating electromagnetic field is applied with a frequency of 80 Hz and an intensity of 0.8 T, inducing the nano-sized organomontmorillonite sheets to be radially oriented along the pipe wall. This achieves the function of the sheet-oriented arrangement blocking water molecule diffusion, improving water resistance, and solving the circumferential strength deficiency.

[0025] Comparison table of water resistance performance.

[0026] Example 4, please refer to Figure 4A high-toughness MPP cable protection pipe is provided, which is made from the following raw materials by melt blending and extrusion molding: 70-85 parts of modified polypropylene matrix resin, 10-20 parts of composite toughening system, 3-8 parts of in-situ fiber-forming component of reinforcing fiber, and 1-5 parts of functional additives. The melt flow rate of the modified polypropylene matrix resin is 0.5-1.5 g / 10 min at 230℃ and 2.16 kg, and the isotacticity of the modified polypropylene matrix resin is greater than or equal to 95%. The composite toughening system is composed of the following materials by weight: 5-12 parts of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 3-8 parts of nano-sized organomontmorillonite, and 2-5 parts of hyperbranched polyesteramide. The nano-sized organomontmorillonite has an interlayer spacing of ≥2.5 nm; the hyperbranched polyesteramide has a terminal hydroxyl functionality of 8-16; the in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melt temperature difference of ≥30°C, and the ratio of polyvinyl alcohol to polyphenylene sulfide is 1:2-2:1; the functional additives are an antioxidant complex, a light stabilizer, and a lubricant, ethylene bis-stearamide; the antioxidant complex is an antioxidant 1010 / 168 complex; the stabilizer is a light stabilizer 944; the modified polypropylene matrix resin is a propylene-ethylene block copolymer, wherein the ethylene segment content is 8-15 wt%, and butyl rubber accounting for 5-10% of the total resin is premixed through dynamic vulcanization technology. Microparticles, butyl rubber microparticles with a particle size of less than or equal to 1 μm, and a grafting rate of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer of 0.8-1.5% in the composite toughening system, maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is pre-assembled with nano-sized organomontmorillonite and hyperbranched polyesteramide at a mass ratio of 3-4:1-2:1 to form core-shell structured composite particles. The shell layer is an intercalation network of nano-sized organomontmorillonite and hyperbranched polyesteramide, and the core layer is maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer. The in-situ fiber-forming component of the reinforcing fiber is induced by a biaxial tensile field during extrusion, and polyvinyl alcohol and polyphenylene sulfide form microfibers with a diameter of 50-200 nm and an aspect ratio greater than or equal to 50. The fibers are oriented axially along the tube with an orientation degree of ≥85%. The ring stiffness of the protective tube is ≥SN12 grade. The drop hammer impact strength of the protective tube at ~30℃ is ≥15kJ / m². The heat distortion temperature of the protective tube at 0.45MPa is ≥125℃. The tube wall has a composite structure of micro-foamed layer and dense skin layer. The density of the micro-foamed layer is 0.7g / cm³, and the cell diameter is ≤50μm. The thickness of the dense skin layer accounts for 25% of the wall thickness. 0.3% of nano-calcium carbonate nucleating agent is added to the micro-foamed layer, and the foaming agent is a compound of endothermic azodicarbonamide and exothermic 4,4'-oxobisbenzenesulfonyl hydrazine in a 1:1 ratio.5. This achieves reduced pipe density, making it lightweight and energy-efficient; the foam structure reduces thermal conductivity, protecting the cable from external temperature differences and improving thermal insulation performance.

[0027] Comparison table of thermal insulation performance.

[0028] Example 5, please refer to Figure 5 A high-toughness MPP cable protection pipe is disclosed. The pipe is made from the following raw materials by melt blending and extrusion molding: 70-85 parts modified polypropylene matrix resin, 10-20 parts composite toughening system, 3-8 parts in-situ fiber-forming component of reinforcing fibers, and 1-5 parts functional additives. The modified polypropylene matrix resin has a melt flow rate of 0.5-1.5 g / 10 min at 230℃ and 2.16 kg, and the isotacticity of the modified polypropylene matrix resin is greater than or equal to 95%. The composite toughening system comprises the following materials by weight: 5-12 parts maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, 3-8 parts nano-sized organomontmorillonite, and 2-5 parts hyperbranched polyesteramide. The nano-sized organomontmorillonite layer... The spacing is greater than or equal to 2.5 nm. The terminal hydroxyl functionality of the hyperbranched polyesteramide is 8-16. The in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melting temperature difference greater than or equal to 30°C. The ratio of polyvinyl alcohol to polyphenylene sulfide is 1:2 to 2:1. The functional additives are an antioxidant complex, a light stabilizer, and a lubricant, ethylene bis-stearamide. The antioxidant complex is an antioxidant 1010 / 168 complex, and the stabilizer is a light stabilizer 944. The outer surface of the protective tube is provided with a spiral corrugated reinforcement structure with a peak height of 5 mm, a wave pitch of 6 mm, and a trapezoidal cross-section with a trapezoidal tilt angle of 50°. Conductive carbon fiber yarns are embedded at the bottom of the corrugations. The diameter of the conductive carbon fiber yarns is 8 μm, and the resistivity is 5 × 10⁻⁶. -4 The shielding network is formed with a strength of Ω·cm, achieving a shielding effectiveness of ≥30dB at a frequency of 1GHz. The inner wall of the protective tube is coated with a hydrophobic coating of nano-silica and fluorosilicone resin, with a coating thickness of 15μm, a contact angle of 152°, and a roll-off angle of ≤5°. This enables the carbon fiber network to form a Faraday cage, reducing frictional resistance during cable laying, dispersing stress through the trapezoidal cross-section, and further improving ring stiffness. Comparison table of corrugated compressive strength.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-toughness MPP cable protection pipe, characterized in that, The protective tube is made from the following raw materials by melt blending and extrusion molding: 70-85 parts modified polypropylene matrix resin, 10-20 parts composite toughening system, 3-8 parts in-situ fiber-forming component of reinforcing fiber, and 1-5 parts functional additives. The melt flow rate of the modified polypropylene matrix resin is 0.5-1.5 g / 10 min at 230℃ and 2.16 kg, and the isotacticity of the modified polypropylene matrix resin is greater than or equal to 95%. The composite toughening system comprises the following materials in parts by weight: 5-12 parts maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer. The composition includes 3-8 parts of nano-sized organomontmorillonite and 2-5 parts of hyperbranched polyesteramide, wherein the interlayer spacing of the nano-sized organomontmorillonite is greater than or equal to 2.5 nm, and the terminal hydroxyl functionalization of the hyperbranched polyesteramide is 8-16. The in-situ fiber-forming component of the reinforcing fiber is a compound of polyvinyl alcohol and polyphenylene sulfide with a melt temperature difference greater than or equal to 30 °C, and the ratio of polyvinyl alcohol to polyphenylene sulfide is 1:2 to 2:

1. The functional additives are an antioxidant complex, a light stabilizer, and a lubricant, ethylene bis-stearamide. The antioxidant complex is an antioxidant 1010 / 168 complex, and the stabilizer is a light stabilizer 944.

2. The high-toughness MPP cable protection pipe according to claim 1, characterized in that: The modified polypropylene matrix resin is a propylene-ethylene block copolymer, wherein the ethylene segment content is 8~15wt%, and 5~10% of butyl rubber microparticles, which account for 5% of the total resin content, are premixed by dynamic vulcanization technology. The particle size of the butyl rubber microparticles is less than or equal to 1μm.

3. The high-toughness MPP cable protection pipe according to claim 1, characterized in that: In the composite toughening system, the grafting rate of maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is 0.8-1.5%. The maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer is pre-assembled with nano-sized organomontmorillonite and hyperbranched polyesteramide in a mass ratio of 3-4:1-2:1 to form core-shell structured composite particles. The shell layer is an intercalation network of nano-sized organomontmorillonite and hyperbranched polyesteramide, and the core layer is maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer.

4. The high-toughness MPP cable protection pipe according to claim 1, characterized in that: During the extrusion process, the in-situ fiber-forming component of the reinforcing fiber is induced by a biaxial tensile field, and polyvinyl alcohol and polyphenylene sulfide form microfibers with a diameter of 50~200nm and an aspect ratio of ≥50. The microfibers are oriented along the axial direction of the tube and the orientation degree is ≥85%.

5. The high-toughness MPP cable protection pipe according to claim 1, characterized in that: The protective tube has a ring stiffness greater than or equal to SN12, a drop hammer impact strength greater than or equal to 15kJ / m² at ~30℃, and a heat deformation temperature greater than or equal to 125℃ at 0.45MPa.

6. The method for preparing a high-toughness MPP cable protection pipe according to claim 1, applicable to the high-toughness MPP cable protection pipe according to any one of claims 1-5, characterized in that: The preparation method of this protective tube includes the following steps: Step 1, Premixing Modification: The components of the composite toughening system are premixed in a high-speed mixer at 80~100℃ for 10~15min to form core-shell composite particles; Step 2, Matrix Activation: The modified polypropylene matrix resin and the in-situ fiber-forming component of the reinforcing fiber are added to the main feed port of the twin-screw extruder and melted and plasticized at the working temperature of 160~180℃ of the twin-screw extruder to form a molten matrix; Step 3, Gradient Blending: The core-shell composite particles obtained in Step 1 are injected into a twin-screw extruder through a side feed port and blended with the molten matrix at 180~210℃ to form a blended melt. The screw speed of the twin-screw extruder is 200~400 rpm, and the shear rate is greater than or equal to 500 s. -1 ; Step 4, In-situ fiber formation and orientation: After the blended melt is extruded through the die of a twin-screw extruder, it immediately enters a biaxial stretching device and is formed under the conditions of longitudinal stretching ratio of 3~5:1 and transverse stretching ratio of 2~3:

1. The cooling and setting temperature is 40~60℃. Step 5, Post-processing: The protective tube is sized and cut to obtain the finished product.

7. The method for preparing a high-toughness MPP cable protection pipe according to claim 6, characterized in that: The gradient blending step 3 employs a three-zone temperature control design: Zone 1 is 180 ± 5°C to allow the polyvinyl alcohol and polyphenylene sulfide to melt and disperse; Zone 2 is 195 ± 5°C to trigger the interface reaction between maleic anhydride-grafted hydrogenated styrene-butadiene block copolymer, nano-sized organomontmorillonite, and hyperbranched polyesteramide core-shell particles and the matrix; Zone 3 is 205 ± 5°C to complete the construction of the dynamic crosslinking network.

8. The method for preparing a high-toughness MPP cable protection pipe according to claim 6, characterized in that: The biaxial stretching device is a composite mechanism of air-expanded radial expansion and tracked axial traction, wherein the radial expansion air pressure is 0.8~1.2MPa and the axial traction speed ratio is 3.0~4.5; in step 4, during the cooling and shaping process, an alternating electromagnetic field is applied, the frequency of the alternating electromagnetic field is 50~100Hz, and the intensity of the alternating electromagnetic field is 0.5~1T, inducing the nano-sized organic montmorillonite sheets to be radially oriented along the pipe wall.

9. A high-toughness MPP cable protection pipe according to any one of claims 1-5, characterized in that: The protective tube has a composite structure of a micro-foamed layer and a dense skin layer. The micro-foamed layer has a density of 0.6~0.8 g / cm³ and a pore diameter of less than or equal to 50 μm. The dense skin layer has a thickness of 20~30% of the wall thickness. 0.2~0.5% of nano-calcium carbonate nucleating agent is added to the micro-foamed layer, and the foaming agent is a compound of endothermic azodicarbonamide and exothermic 4,4'-oxobisbenzenesulfonyl hydrazine, with a compounding ratio of 1:1~1:

2.

10. A high-toughness MPP cable protection pipe according to claim 1, characterized in that: The outer surface of the protective tube is provided with a spiral corrugated reinforcement structure, with a peak height of 4-6 mm, a wave pitch of 8-12 mm, and a trapezoidal cross-section with a trapezoidal inclination angle of 45-60°. Conductive carbon fiber yarns are embedded at the bottom of the corrugations, with a diameter of 7-10 μm and a resistivity of less than or equal to 10 μm. -3 The shielding tube is coated with nano-silica and fluorosilicone resin hydrophobic coatings, with a thickness of 10~20μm, a contact angle of ≥150°, and a roll-off angle of ≤5°. The inner wall of the protective tube is coated with nano-silica and fluorosilicone resin hydrophobic coatings, with a contact angle of ≥150° and a roll-off angle of ≤5°.

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