A method for manufacturing a steel belt reinforced spiral wound cable protection pipe

Abstract

This application relates to the field of cable protection pipe manufacturing technology, and discloses a method for preparing a steel-reinforced spiral cable protection pipe, comprising the following steps: mixing block copolymer polypropylene, ethylene-vinyl alcohol copolymer, hydroxyl-terminated highly branched polyester, ethylene-1-octene copolymer, microcrystalline wax, and electromagnetic rheology premixed masterbatch, and feeding the mixture into a co-rotating twin-screw extruder; injecting a crosslinking solution during extrusion to dynamically vulcanize the ethylene-1-octene copolymer, and extruding a composite melt; heating the surface of a corrugated galvanized steel strip using a medium-frequency induction heating coil, coating the heated galvanized steel strip surface with the composite melt and spirally winding it to obtain a preliminary pipe; introducing the preliminary pipe into a circulating water bath cooling tank with ultrasonic transducers for cooling and solidification, and then traction cutting to obtain a steel-reinforced spiral cable protection pipe. This invention improves the impact toughness, interfacial peel strength, and dimensional stability of the steel-reinforced spiral cable protection pipe.

Description

Technical Field

[0001] This invention relates to the field of cable protection pipe manufacturing technology, specifically a method for preparing a steel strip reinforced wound cable protection pipe. Background Technology

[0002] Steel-reinforced spiral cable protection pipes provide ring stiffness through a metal steel strip and corrosion resistance and electrical insulation through a polymer coating. They are widely used in underground cable laying projects. In the existing extrusion coating process of steel-reinforced spiral cable protection pipes, when the high-temperature polymer melt directly contacts the room-temperature metal steel strip, the polymer melt undergoes rapid cooling and contraction upon contact with the room-temperature metal. This cooling and contraction causes the polymer macromolecular chain segments to freeze rapidly, limiting the polymer's ability to penetrate into the micropores on the surface of the metal steel strip. This results in insufficient interfacial peel strength between the polymer layer and the metal steel strip, making the steel-reinforced spiral cable protection pipe prone to delamination under stress.

[0003] To improve the impact resistance of polymer coatings, existing processes generally add elastomer components to the base resin for physical blending. However, simple physical blending is difficult to balance the impact toughness and extrusion processing fluidity of composite materials. Increasing the amount of elastomer components will lead to an increase in the apparent viscosity of the composite melt, causing torque overload of extrusion equipment and rough surface defects of steel strip reinforced spiral cable protection pipes.

[0004] In existing steel-reinforced spiral wound cable protection pipes, the cooling process after extrusion molding generally employs conventional circulating water bath cooling. When the high-temperature pipe enters the cooling water tank, the cooling water on the pipe surface vaporizes, forming an insulating vapor film. This insulating vapor film hinders heat transfer, resulting in differences in cooling rates along the inner and outer walls and the thickness of the cross-section of the steel-reinforced spiral wound cable protection pipe. This uneven cooling rate distribution causes residual internal stress to accumulate in the polymer material during crystallization and shrinkage. The presence of residual internal stress reduces the dimensional stability of the steel-reinforced spiral wound cable protection pipe, leading to a decrease in its overall mechanical properties. Therefore, this invention proposes a method for manufacturing steel-reinforced spiral wound cable protection pipes to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a steel-reinforced spiral cable protection pipe, which solves the problems of insufficient interfacial bonding between the polymer matrix and the metal steel strip during the processing of existing steel-reinforced spiral cable protection pipes, and the difficulty in balancing the impact toughness and processing fluidity of the composite material, resulting in unstable mechanical properties of the pipe.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a steel strip reinforced spiral cable protection pipe includes the following steps: Block copolymer polypropylene, ethylene-vinyl alcohol copolymer, hydroxyl-terminated highly branched polyester, ethylene-1-octene copolymer, microcrystalline wax and electromagnetic rheology premixed masterbatch are physically mixed to obtain a mixture, which is then fed into the main feed port of a co-rotating twin-screw extruder. The co-rotating twin-screw extruder is programmed to increase the temperature. A crosslinking solution is injected into the middle section of the co-rotating twin-screw extruder to perform dynamic vulcanization treatment of the ethylene-1-octene copolymer. A vacuum pump is turned on in the exhaust section of the co-rotating twin-screw extruder to perform azeotropic devolatilization. The composite melt is then extruded through the die of the co-rotating twin-screw extruder. Galvanized steel strip is pressed into a corrugated shape, and the surface of the galvanized steel strip is heated by a medium-frequency induction heating coil. The composite melt is then wrapped around the heated galvanized steel strip and spirally overlapped to obtain the initial state pipe. The initial state of the pipe is introduced into a circulating water bath cooling tank equipped with ultrasonic transducers for cooling and solidification. After traction and fixed-length cutting, a steel strip reinforced spiral cable protection pipe is obtained.

[0007] By adopting the above technical solution, block copolymer polypropylene is used as the structural matrix, ethylene-vinyl alcohol copolymer is added to provide barrier properties, ethylene-1-octene copolymer is added as the elastomer phase, and electromagnetic rheological premixed masterbatch is added to adjust the rheological properties of the composite melt. Physical mixing and melt processing are carried out through a co-rotating twin-screw extruder.

[0008] During the extrusion process, a crosslinking solution is injected to dynamically vulcanize the ethylene-1-octene copolymer. The mechanism of dynamic vulcanization is as follows: under high-temperature shearing, the crosslinking solution initiates a crosslinking reaction of the ethylene-1-octene copolymer molecular chains. As the crosslinking reaction proceeds, the ethylene-1-octene copolymer transforms from a linear macromolecule into a three-dimensional network structure. Simultaneously, under the mechanical shearing action of the co-rotating twin-screw extruder, the crosslinked ethylene-1-octene copolymer is broken down and uniformly dispersed in the continuous phase of block copolymer polypropylene in the form of micron-sized crosslinked rubber particles, forming a thermoplastic dynamically vulcanized rubber structure. The dispersed crosslinked rubber particles can absorb impact energy and induce crazing and shear bands in the matrix, thereby improving the impact toughness of the composite melt.

[0009] The galvanized steel strip is heated by a medium-frequency induction heating coil, which raises the surface temperature of the galvanized steel strip. When the composite melt is coated on the heated surface of the galvanized steel strip, the high-temperature surface of the galvanized steel strip prevents the composite melt from cooling and shrinking rapidly at the moment of contact. This ensures that the polymer chain segments maintain sufficient mobility on the surface of the galvanized steel strip, promoting the penetration of the polymer chain segments into the micropores of the galvanized steel strip surface and forming a mechanically interlocked structure.

[0010] The initial state pipe containing the composite melt is introduced into a circulating water bath cooling tank equipped with ultrasonic transducers. The ultrasonic transducers generate cavitation and micro-acoustic flow effects in the circulating water, which break the vapor film on the surface of the initial state pipe, improve heat exchange efficiency, make the cooling rate of the inner and outer walls of the initial state pipe more uniform, eliminate residual internal stress generated during the polymer crystallization process, and at the same time, the mechanical vibration energy of the ultrasonic waves is transferred to the incompletely solidified composite melt, promoting the uniform distribution of electromagnetic rheological premixed masterbatch inside the composite melt.

[0011] Therefore, it improves the impact toughness of the pipe, the interfacial peel strength between the polymer and the metal strip, and the dimensional stability of the product.

[0012] Preferably, the material ratio range of the physical mixture is: 60-80 parts by mass of block copolymer polypropylene, 3-8 parts by mass of ethylene-vinyl alcohol copolymer, 1-5 parts by mass of hydroxyl-terminated highly branched polyester, 5-12 parts by mass of ethylene-1-octene copolymer, 1-5 parts by mass of microcrystalline wax, and 4.5-9 parts by mass of electromagnetic rheology premixed masterbatch.

[0013] By employing the above technical solution and controlling the material ratio of physical mixing, the number of elastomer particles formed by dynamic vulcanization is kept within a range that effectively toughens the polypropylene block copolymer matrix without disrupting its continuity. Hydroxyl-terminated highly branched polyester and microcrystalline wax are used in combination at predetermined mass ratios to provide internal lubrication at the molecular level and external release effect, reducing the apparent viscosity of the composite melt.

[0014] Preferably, the co-rotating twin-screw extruder includes a feeding and plasticizing section in zones one to three, a homogenization and dynamic vulcanization section in zones four to seven, a venting section in zone eight, and a die section; the crosslinking solution is injected in zone four of the homogenization and dynamic vulcanization section in zones four to seven.

[0015] The temperature of the feeding and plasticizing sections in zones one to three of the co-rotating twin-screw extruder is set to 165–180°C. The temperature of the homogenization and dynamic vulcanization zones four to seven of the co-rotating twin-screw extruder is set to 205–215°C. The temperature of the eighth-zone exhaust section of the co-rotating twin-screw extruder is set to 200–210°C. The temperature of the die section of the co-rotating twin-screw extruder is set to 195–205°C; Maintain the vacuum level of the eight-zone exhaust section of the co-rotating twin-screw extruder at -0.085 to -0.095 MPa.

[0016] By adopting the above technical solution, a distributed temperature control zone is established. The temperature of the feeding and plasticizing section in zones one to three ensures that the base resin is completely melted. The temperature of the homogenization and dynamic vulcanization section in zones four to seven provides the activation energy required for the crosslinking reaction. The crosslinking solution is injected in zone four, providing sufficient residence time to complete the crosslinking reaction of the ethylene-1-octene copolymer. The exhaust section in zone eight, in conjunction with vacuum control, produces an azeotropic devolatilization effect. The solvent in the crosslinking solution is used as an azeotropic agent to remove reaction byproducts and residual small molecule volatiles, thus avoiding the generation of porosity defects inside the composite melt.

[0017] Preferably, the crosslinking solution is composed of 0.3 to 1.0 parts by weight of octylphenol formaldehyde resin, 0.3 to 1.0 parts by weight of stannous chloride dihydrate, and 0.3 to 0.8 parts by weight of 2,2,4-trimethylpentane.

[0018] By employing the above technical solution, octylphenol formaldehyde resin is used as a crosslinking agent, and stannous chloride dihydrate is used as a Lewis acid catalyst. Under the high-temperature environment of the homogenization and dynamic vulcanization stages, the hydroxymethyl group of octylphenol formaldehyde resin loses water molecules to form a carbocation intermediate under the catalysis of stannous chloride dihydrate. The carbocation intermediate attacks the tertiary carbon atom position on the ethylene-1-octene copolymer molecular chain and undergoes an electrophilic substitution reaction, thereby constructing stable carbon-carbon crosslinking bonds between the ethylene-1-octene copolymer molecular chains. 2,2,4-trimethylpentane is used as a nonpolar solvent to promote the penetration and diffusion of octylphenol formaldehyde resin in the ethylene-1-octene copolymer phase and improve the crosslinking reaction rate.

[0019] Preferably, the preparation steps of the hydroxyl-terminated highly branched polyester include: In a reactor equipped with a mechanical stirrer, a nitrogen inlet device, and a water separator, 1–2 mol of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, 15–20 mol of 2,2-bis(hydroxymethyl)propionic acid, and 0.2–0.4 wt% of p-toluenesulfonic acid, representing the total mass of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 2,2-bis(hydroxymethyl)propionic acid, are added. Under nitrogen protection, the reactor is heated to 120-140℃ to carry out esterification reaction for 2-3 hours. After the water generated by the esterification reaction is collected by the water separator, the internal pressure of the reactor is evacuated to -0.09 to -0.095 MPa and the melt polycondensation reaction is continued at 120-140℃ for 3-5 hours. The reaction vessel was cooled to 20-30°C, the polycondensation product was extracted, and the polycondensation product was dissolved in acetone. The product was then purified by ice-water precipitation and vacuum dried to obtain a hydroxyl-terminated highly branched polyester.

[0020] By employing the above technical solution, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, containing three hydroxyl groups, is used as the central core molecule, and 2,2-bis(hydroxymethyl)propionic acid, containing one carboxyl group and two hydroxyl groups, is used as the branching monomer. A stepwise polycondensation reaction occurs under the catalysis of p-toluenesulfonic acid.

[0021] The specific reaction process is as follows: the hydroxyl group of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol undergoes a dehydration condensation reaction with the carboxyl group of 2,2-bis(hydroxymethyl)propionic acid to form an ester bond, generating a first-generation branched macromolecule. The first-generation branched macromolecule has multiple unreacted hydroxyl groups on its periphery. The unreacted hydroxyl groups continue to undergo esterification condensation with the excess carboxyl group of 2,2-bis(hydroxymethyl)propionic acid in the system to form a branched structure. The initial atmospheric pressure esterification reaction combined with the later vacuum dehydration condensation promotes the forward condensation reaction.

[0022] The synthesized hydroxyl-terminated hyperbranched polyester possesses a highly dense three-dimensional spherical molecular structure. The molecular chains do not undergo chain entanglement and exist in a random coil state. During processing, it can effectively reduce the frictional resistance between the block copolymer polypropylene macromolecular chains, acting as a rheology modifier. Simultaneously, the numerous polar hydroxyl groups distributed on the periphery of the hydroxyl-terminated hyperbranched polyester can form hydrogen bonds with the ethylene-vinyl alcohol copolymer, improving the compatibility of the ethylene-vinyl alcohol copolymer in the nonpolar block copolymer polypropylene matrix.

[0023] Preferably, the electromagnetic rheological premixed masterbatch is made by mixing polyisobutylene with surface-modified carbonyl iron powder; The preparation steps of surface-modified carbonyl iron powder include: 100-120 parts by weight of raw carbonyl iron powder are dispersed in a mixed solvent consisting of 400-500 parts by weight of anhydrous ethanol and 40-60 parts by weight of deionized water, and the pH of the mixed solvent is adjusted to 4.0-4.5 using glacial acetic acid. Add 1.5 to 3.0 parts by weight of γ-methacryloxypropyltrimethoxysilane to the mixed solvent, place the mixed solvent in a constant temperature water bath at 50 to 70°C, and set the mechanical stirring speed to 200 to 400 rpm to mechanically stir the mixed solvent for 2 to 4 hours. After the reaction was completed, the mixed solvent was treated with a centrifuge and the solid product was extracted. The solid product was washed three times with anhydrous ethanol and then dried in a vacuum oven at 70-90°C for 10-14 hours to obtain surface-modified carbonyl iron powder.

[0024] The preparation steps of the electromagnetic rheological premixed masterbatch include: 15-25 parts by mass of the polyisobutylene and 10 parts by mass of the surface-modified carbonyl iron powder are fed into an internal mixer. The working temperature of the internal mixer is set to 70-90°C and the speed of the internal mixer is set to 30-50 rpm. Polyisobutylene and surface-modified carbonyl iron powder were subjected to low-shear intensive mixing for 10-20 minutes. After mixing, the mixture was discharged and naturally cooled at 20-30°C to obtain electromagnetic rheological premixed masterbatch.

[0025] By adopting the above technical solution, in the environment of acidic deionized water and anhydrous ethanol, the trimethoxy group of γ-methacryloxypropyltrimethoxysilane undergoes a hydrolysis reaction to generate silanol group. The silanol group then undergoes a dehydration condensation reaction with the metal hydroxyl group on the surface of the original carbonyl iron powder to form a silicon-oxygen-iron chemical bond.

[0026] The reaction mechanism is as follows: the inorganic affinity group at one end of the γ-methacryloxypropyltrimethoxysilane molecule is fixed on the surface of the original carbonyl iron powder, and the methacryloxy carbon-carbon double bond at the other end of the γ-methacryloxypropyltrimethoxysilane molecule faces outward, changing the surface of the original carbonyl iron powder from hydrophilic to lipophilic.

[0027] When surface-modified carbonyl iron powder and polyisobutylene are mixed in an internal mixer, the long-chain molecules of polyisobutylene can coat the outside of the surface-modified carbonyl iron powder. Polyisobutylene has damping properties and self-adhesion. After being made into an electromagnetic rheological premixed masterbatch, it is added to the extrusion system. When the composite melt is coated onto the surface of galvanized steel strip, the thickening effect of polyisobutylene can improve the initial peel strength between the polymer layer and the metal layer. The surface-modified carbonyl iron powder generates micro-orientation in the medium-frequency induction heating magnetic field region, which promotes the local regular arrangement of polymer matrix molecular chains and improves the overall rigidity of the product.

[0028] Preferably, the thickness of the galvanized steel strip is 0.6 to 1.2 mm, the surface of the galvanized steel strip is heated to 175 to 185°C, and the spiral lap winding speed is set to 5 to 15 m / min.

[0029] By adopting the above technical solution, the extrusion temperature of the composite melt is matched, the interface temperature gradient between the composite melt and the galvanized steel strip is reduced, and interface crystallization defects in the composite melt are prevented.

[0030] Preferably, the frequency of the ultrasonic transducer is set to 25–30 kHz, and the power density of the ultrasonic transducer is set to 0.2–0.5 W / cm². 2 The ambient water temperature of the circulating water bath cooling tank is set at 15-25℃, and the initial state of the pipe material is cooled to complete solidification in the circulating water bath cooling tank for 10-30 seconds.

[0031] By adopting the above technical solution, an ultrasonic transducer with a set frequency and power density can generate a sound field. The cavitation bubble caused by the sound field collapses instantly to generate a micro-jet, which peels off the insulating vapor film on the surface of the initial pipe, achieving uniform cooling and preventing thermal stress cracks from forming on the cross section of the initial pipe.

[0032] This invention provides a method for preparing a steel-reinforced spiral cable protection pipe. It has the following beneficial effects: 1. In this invention, a crosslinking solution is injected into the extrusion process of a co-rotating twin-screw extruder to dynamically vulcanize the ethylene-1-octene copolymer. The crosslinking solution initiates a crosslinking reaction in the ethylene-1-octene copolymer to generate micron-sized crosslinked rubber particles. These crosslinked rubber particles are uniformly dispersed in the continuous phase of block copolymer polypropylene. They can absorb impact energy when the steel-reinforced spiral cable protection pipe is subjected to external impact, and induce the formation of crazing and shear bands in the continuous phase of block copolymer polypropylene, thereby improving the impact toughness of the steel-reinforced spiral cable protection pipe.

[0033] 2. This invention heats the surface of the galvanized steel strip using a medium-frequency induction heating coil, preventing the composite melt from rapidly cooling and shrinking upon contact with the galvanized steel strip surface. This promotes the penetration of polymer chains within the composite melt into the micropores of the galvanized steel strip surface, forming a mechanically interlocking structure. Combined with the physical adhesion-enhancing effect of polyisobutylene in the electromagnetic rheological premixed masterbatch of the composite melt, the interfacial peel strength between the composite melt and the galvanized steel strip is improved, preventing delamination and peeling of the steel strip reinforced spiral cable protection pipe during processing and use.

[0034] 3. In this invention, the initial state pipe is introduced into a circulating water bath cooling tank equipped with ultrasonic transducers for cooling and solidification. The ultrasonic transducers generate a cavitation effect in the circulating water bath cooling tank. When the cavitation bubbles collapse, micro-jet streams are generated. The micro-jet streams destroy the insulating vapor film on the surface of the initial state pipe, making the cooling rate of the inner and outer walls of the initial state pipe more uniform. The uniform cooling rate eliminates the residual internal stress generated in the cross-section of the initial state pipe during the polymer crystallization process, prevents thermal stress cracks from occurring after the steel strip reinforced spiral cable protection pipe is formed, and improves the dimensional stability of the steel strip reinforced spiral cable protection pipe. Attached Figure Description

[0035] Figure 1 This is a schematic diagram comparing the change of the linear expansion coefficient of pipe samples with temperature in an embodiment of the present invention; Figure 2 This is a schematic diagram showing the change of the linear expansion coefficient of the comparative pipe sample of the present invention with temperature. Figure 3 This is a schematic diagram showing the change of internal temperature of a pipe sample in an alternating magnetic field over time, as an embodiment of the present invention. Figure 4This is a comparative schematic diagram showing the change of internal temperature of the comparative pipe sample of the present invention over time in an alternating magnetic field. Figure 5 This is a schematic diagram showing the comparison of the ring stiffness test of the pipe samples of the present invention; Figure 6 This is a schematic diagram comparing the peel strength between the resin layer and the galvanized steel strip layer of the pipe sample of the present invention; Figure 7 This is a schematic diagram comparing the average absorbed energy of the drop hammer impact damage of the pipe samples of the present invention under 0°C freezing conditions. Figure 8 This is a schematic diagram comparing the tensile strength recovery rate of the 1B dumbbell-shaped tensile test specimen after heat treatment in a constant temperature oven according to the present invention. Figure 9 This is a schematic diagram of the tensile strength recovery rate of the 1B dumbbell-shaped tensile test specimen after alternating magnetic field induction heating treatment according to the present invention. Detailed Implementation

[0036] The technical solutions in 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.

[0037] Preparation Examples 1-9: Preparation Example 1: This preparation example provides a method for preparing hydroxyl-terminated highly branched polyesters, including the following steps: In a reactor equipped with a mechanical stirrer, a nitrogen inlet device, and a water separator, 1 mol of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 15 mol of 2,2-bis(hydroxymethyl)propionic acid are added, followed by the addition of p-toluenesulfonic acid, which accounts for 0.2 wt% of the total mass of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 2,2-bis(hydroxymethyl)propionic acid.

[0038] Under nitrogen protection, the reactor temperature is raised to 120°C and maintained at 120°C for 2 hours for esterification. After the water generated by the esterification reaction is collected by the water separator, the internal pressure of the reactor is evacuated to -0.09 MPa, and the melt polycondensation reaction continues at 120°C for 3 hours.

[0039] After the melt polycondensation reaction was completed, the reactor was cooled to room temperature (25°C), the polycondensation product was extracted, and the polycondensation product was dissolved in acetone. Then, the polycondensation product was purified by ice-water precipitation. Finally, the purified product was placed in a vacuum drying oven for vacuum drying to obtain a hydroxyl-terminated highly branched polyester.

[0040] Preparation Example 2: This preparation example provides a method for preparing hydroxyl-terminated highly branched polyesters, including the following steps: In a reactor equipped with a mechanical stirrer, a nitrogen inlet device, and a water separator, 1.5 mol of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 18 mol of 2,2-bis(hydroxymethyl)propionic acid are added, followed by the addition of p-toluenesulfonic acid, which accounts for 0.3 wt% of the total mass of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 2,2-bis(hydroxymethyl)propionic acid.

[0041] Under nitrogen protection, the reactor temperature is raised to 130°C and maintained at 130°C for 2.5 hours for esterification. After the water generated by the esterification reaction is collected by the water separator, the internal pressure of the reactor is evacuated to -0.09 MPa, and the melt polycondensation reaction continues at 130°C for 4 hours.

[0042] After the melt polycondensation reaction was completed, the reactor was cooled to room temperature (20°C), the polycondensation product was extracted, and the polycondensation product was dissolved in acetone. Subsequently, the polycondensation product was purified by ice-water precipitation. Finally, the purified product was placed in a vacuum drying oven for vacuum drying to obtain a hydroxyl-terminated highly branched polyester.

[0043] Preparation Example 3: This preparation example provides a method for preparing hydroxyl-terminated highly branched polyesters, including the following steps: In a reactor equipped with a mechanical stirrer, a nitrogen inlet device, and a water separator, 2 mol of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 20 mol of 2,2-bis(hydroxymethyl)propionic acid are added, followed by the addition of p-toluenesulfonic acid, which accounts for 0.4 wt% of the total mass of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 2,2-bis(hydroxymethyl)propionic acid.

[0044] Under nitrogen protection, the reactor temperature is raised to 140°C and maintained at 140°C for 3 hours for esterification. After the water generated by the esterification reaction is collected by the water separator, the internal pressure of the reactor is evacuated to -0.095 MPa, and the melt polycondensation reaction continues at 140°C for 5 hours.

[0045] After the melt polycondensation reaction was completed, the reactor was cooled to room temperature (30°C), the polycondensation product was extracted, and the polycondensation product was dissolved in acetone. Then, the polycondensation product was purified by ice-water precipitation. Finally, the purified product was placed in a vacuum drying oven for vacuum drying to obtain a hydroxyl-terminated highly branched polyester.

[0046] Preparation Example 4: This preparation example provides a method for preparing surface-modified carbonyl iron powder, including the following steps: 100 parts by weight of raw carbonyl iron powder were dispersed in a mixed solvent consisting of 400 parts by weight of anhydrous ethanol and 40 parts by weight of deionized water, and the pH of the mixed solvent was adjusted to 4.0 using glacial acetic acid.

[0047] Subsequently, 1.5 parts by mass of γ-methacryloxypropyltrimethoxysilane were added dropwise to the mixed solvent. The mixed solvent was placed in a 50°C constant temperature water bath and the mechanical stirring device was set to 200 rpm for 2 hours.

[0048] After the reaction was completed, the mixed solvent was treated with a centrifuge and the solid product was extracted. The solid product was washed three times with anhydrous ethanol. Finally, the washed solid product was placed in a vacuum oven at 70°C and dried for 10 hours to obtain surface-modified carbonyl iron powder.

[0049] Preparation Example 5: This preparation example provides a method for preparing surface-modified carbonyl iron powder, including the following steps: 110 parts by weight of raw carbonyl iron powder were dispersed in a mixed solvent consisting of 450 parts by weight of anhydrous ethanol and 50 parts by weight of deionized water, and the pH of the mixed solvent was adjusted to 4.2 using glacial acetic acid.

[0050] Subsequently, 2.2 parts by mass of γ-methacryloyloxypropyltrimethoxysilane were added dropwise to the mixed solvent. The mixed solvent was placed in a 60°C constant temperature water bath, and the mechanical stirring device was set to 300 rpm for 3 hours.

[0051] After the reaction was completed, the mixed solvent was treated with a centrifuge and the solid product was extracted. The solid product was washed three times with anhydrous ethanol. Finally, the washed solid product was placed in a vacuum oven at 80°C and dried for 12 hours to obtain surface-modified carbonyl iron powder.

[0052] Preparation Example 6: This preparation example provides a method for preparing surface-modified carbonyl iron powder, including the following steps: 120 parts by weight of raw carbonyl iron powder were dispersed in a mixed solvent consisting of 500 parts by weight of anhydrous ethanol and 60 parts by weight of deionized water, and the pH of the mixed solvent was adjusted to 4.5 using glacial acetic acid.

[0053] Subsequently, 3.0 parts by mass of γ-methacryloxypropyltrimethoxysilane were added dropwise to the mixed solvent. The mixed solvent was placed in a 70°C constant temperature water bath and the mechanical stirring device was set to 400 rpm for 4 hours.

[0054] After the reaction was completed, the mixed solvent was treated with a centrifuge and the solid product was extracted. The solid product was washed three times with anhydrous ethanol. Finally, the washed solid product was placed in a vacuum oven at 90°C and dried for 14 hours to obtain surface-modified carbonyl iron powder.

[0055] Preparation Example 7: This preparation example provides a method for preparing electromagnetic rheological premixed masterbatch, including the following steps: 20 parts by mass of polyisobutylene and 10 parts by mass of surface-modified carbonyl iron powder prepared in Preparation Example 5 were fed into an internal mixer.

[0056] Set the internal mixer operating temperature to 80℃ and the internal mixer speed to 40rpm, and perform low-shear internal mixing for 15 minutes.

[0057] After the mixing process is completed, the material is discharged and naturally cooled at 25°C to obtain electromagnetic rheological premixed masterbatch.

[0058] Preparation Example 8: This preparation example provides a method for preparing electromagnetic rheological premixed masterbatch, including the following steps: 15 parts by mass of polyisobutylene and 10 parts by mass of surface-modified carbonyl iron powder prepared in Preparation Example 4 were fed into an internal mixer.

[0059] Set the internal mixer operating temperature to 70℃ and the internal mixer speed to 30rpm, and perform low-shear internal mixing for 10 minutes.

[0060] After the mixing process is completed, the material is discharged and naturally cooled at 20°C to obtain electromagnetic rheological premixed masterbatch.

[0061] Preparation Example 9: This preparation example provides a method for preparing electromagnetic rheological premixed masterbatch, including the following steps: 25 parts by mass of polyisobutylene and 10 parts by mass of surface-modified carbonyl iron powder prepared in Preparation Example 6 were fed into an internal mixer.

[0062] Set the internal mixer operating temperature to 90℃ and the internal mixer speed to 50rpm, and perform low-shear internal mixing for 20 minutes.

[0063] After the mixing process is completed, the material is discharged and naturally cooled at 30°C to obtain electromagnetic rheological premixed masterbatch.

[0064] Examples 1-5: Example 1: This embodiment provides a method for preparing a steel strip reinforced spiral cable protection pipe, including the following steps: 70 parts by mass of block copolymer polypropylene, 5.5 parts by mass of ethylene-vinyl alcohol copolymer, 3 parts by mass of hydroxyl-terminated highly branched polyester prepared in Preparation Example 2, 8.5 parts by mass of ethylene-1-octene copolymer, 3 parts by mass of microcrystalline wax, and 6 parts by mass of electromagnetic rheological premixed masterbatch prepared in Preparation Example 7 were physically mixed, and the resulting mixture was fed into the main feed port of a co-rotating twin-screw extruder.

[0065] The temperature of the feeding and plasticizing section in zones one to three of the co-rotating twin-screw extruder is set at 175℃, the temperature of the homogenization and dynamic vulcanization section in zones four to seven of the co-rotating twin-screw extruder is set at 210℃, the temperature of the venting section in zone eight of the co-rotating twin-screw extruder is set at 205℃, and the temperature of the die section of the co-rotating twin-screw extruder is set at 200℃.

[0066] A crosslinking solution was prepared by dissolving 0.6 parts by weight of octylphenol formaldehyde resin and 0.6 parts by weight of stannous chloride dihydrate in 0.5 parts by weight of 2,2,4-trimethylpentane. The crosslinking solution was then injected into the co-rotating twin-screw extruder in zone four using a high-pressure liquid metering pump.

[0067] In the eighth zone of the co-rotating twin-screw extruder, the vacuum pump is turned on to maintain the vacuum level of the exhaust section of the co-rotating twin-screw extruder at -0.09MPa for azeotropic devolatilization.

[0068] A 0.8mm thick galvanized steel strip is pressed into a corrugated shape using a roller pressing device. The surface of the galvanized steel strip is heated to 180℃ using a medium-frequency induction heating coil. The composite melt extruded from the die of a co-rotating twin-screw extruder is then wrapped onto the heated galvanized steel strip surface using a winding machine, and spirally overlapped at a winding speed of 10m / min to obtain the initial state pipe.

[0069] The initial state pipe is directly introduced into the circulating water bath cooling tank. A 28kHz frequency, 0.35W / cm² power density device is installed at the bottom of the rear section of the circulating water bath cooling tank. 2 The ultrasonic transducer, the initial state of the pipe is cooled to complete solidification in an ambient water temperature of 20℃ for 20 seconds, and then traction and fixed-length cutting are used to obtain a steel strip reinforced spiral cable protection pipe.

[0070] Example 2: This embodiment provides a method for preparing a steel strip reinforced spiral cable protection pipe, including the following steps: 80 parts by mass of block copolymer polypropylene, 3 parts by mass of ethylene-vinyl alcohol copolymer, 1 part by mass of hydroxyl-terminated highly branched polyester prepared in Preparation Example 1, 5 parts by mass of ethylene-1-octene copolymer, 1 part by mass of microcrystalline wax, and 4.5 parts by mass of electromagnetic rheological premixed masterbatch prepared in Preparation Example 8 were physically mixed, and the mixture obtained by physical mixing was fed into the main feed port of a co-rotating twin-screw extruder.

[0071] The temperature of the feeding and plasticizing section in zones one to three of the co-rotating twin-screw extruder is set at 175℃, the temperature of the homogenization and dynamic vulcanization section in zones four to seven of the co-rotating twin-screw extruder is set at 210℃, the temperature of the venting section in zone eight of the co-rotating twin-screw extruder is set at 205℃, and the temperature of the die section of the co-rotating twin-screw extruder is set at 200℃.

[0072] A crosslinking solution was prepared by dissolving 0.3 parts by weight of octylphenol formaldehyde resin and 0.3 parts by weight of stannous chloride dihydrate in 0.3 parts by weight of 2,2,4-trimethylpentane. The crosslinking solution was then injected into the co-rotating twin-screw extruder in zone four using a high-pressure liquid metering pump.

[0073] In the eighth zone of the co-rotating twin-screw extruder, the vacuum pump is turned on to maintain the vacuum level of the exhaust section of the co-rotating twin-screw extruder at -0.09MPa for azeotropic devolatilization.

[0074] A 0.6mm thick galvanized steel strip is pressed into a corrugated shape using a roller pressing device. The surface of the galvanized steel strip is heated to 180℃ using a medium-frequency induction heating coil. The composite melt extruded from the die of a co-rotating twin-screw extruder is then wrapped onto the heated galvanized steel strip surface using a winding machine, and spirally overlapped and wound at a winding speed of 10m / min to obtain the initial state pipe.

[0075] The initial state pipe is directly introduced into the circulating water bath cooling tank. A 25kHz frequency, 0.35W / cm² power density device is installed at the bottom of the rear section of the circulating water bath cooling tank. 2 The ultrasonic transducer, the initial state of the pipe is cooled to complete solidification in an ambient water temperature of 20℃ for 20 seconds, and then traction and fixed-length cutting are used to obtain a steel strip reinforced spiral cable protection pipe.

[0076] Example 3: This embodiment provides a method for preparing a steel strip reinforced spiral cable protection pipe, including the following steps: 60 parts by mass of block copolymer polypropylene, 8 parts by mass of ethylene-vinyl alcohol copolymer, 5 parts by mass of hydroxyl-terminated highly branched polyester prepared in Preparation Example 3, 12 parts by mass of ethylene-1-octene copolymer, 5 parts by mass of microcrystalline wax, and 9 parts by mass of electromagnetic rheological premixed masterbatch prepared in Preparation Example 9 were physically mixed, and the mixture obtained by physical mixing was fed into the main feed port of a co-rotating twin-screw extruder.

[0077] The temperature of the feeding and plasticizing section in zones one to three of the co-rotating twin-screw extruder is set at 175℃, the temperature of the homogenization and dynamic vulcanization section in zones four to seven of the co-rotating twin-screw extruder is set at 210℃, the temperature of the venting section in zone eight of the co-rotating twin-screw extruder is set at 205℃, and the temperature of the die section of the co-rotating twin-screw extruder is set at 200℃.

[0078] A crosslinking solution was prepared by dissolving 1.0 parts by weight of octylphenol formaldehyde resin and 1.0 parts by weight of stannous chloride dihydrate in 0.8 parts by weight of 2,2,4-trimethylpentane. The crosslinking solution was then injected into the co-rotating twin-screw extruder in zone four using a high-pressure liquid metering pump.

[0079] In the eighth zone of the co-rotating twin-screw extruder, the vacuum pump is turned on to maintain the vacuum level of the exhaust section of the co-rotating twin-screw extruder at -0.09MPa for azeotropic devolatilization.

[0080] A 1.2mm thick galvanized steel strip is pressed into a corrugated shape using a roller pressing device. The surface of the galvanized steel strip is heated to 180℃ using a medium-frequency induction heating coil. The composite melt extruded from the die of a co-rotating twin-screw extruder is then wrapped onto the heated galvanized steel strip surface using a winding machine, and spirally overlapped at a winding speed of 10m / min to obtain the initial state pipe.

[0081] The initial state pipe is directly introduced into the circulating water bath cooling tank. A 30kHz frequency, 0.35W / cm² power density device is installed at the bottom of the rear section of the circulating water bath cooling tank. 2 The ultrasonic transducer, the initial state of the pipe is cooled to complete solidification in an ambient water temperature of 20℃ for 20 seconds, and then traction and fixed-length cutting are used to obtain a steel strip reinforced spiral cable protection pipe.

[0082] Example 4: This embodiment provides a method for preparing a steel strip reinforced spiral cable protection pipe, including the following steps: 70 parts by mass of block copolymer polypropylene, 5.5 parts by mass of ethylene-vinyl alcohol copolymer, 3 parts by mass of hydroxyl-terminated highly branched polyester prepared in Preparation Example 2, 8.5 parts by mass of ethylene-1-octene copolymer, 3 parts by mass of microcrystalline wax, and 6 parts by mass of electromagnetic rheological premixed masterbatch prepared in Preparation Example 7 were physically mixed, and the resulting mixture was fed into the main feed port of a co-rotating twin-screw extruder.

[0083] The temperature of the feeding and plasticizing section in zones one to three of the co-rotating twin-screw extruder is set to 165℃, the temperature of the homogenization and dynamic vulcanization section in zones four to seven of the co-rotating twin-screw extruder is set to 205℃, the temperature of the venting section in zone eight of the co-rotating twin-screw extruder is set to 200℃, and the temperature of the die section of the co-rotating twin-screw extruder is set to 195℃.

[0084] A crosslinking solution was prepared by dissolving 0.6 parts by weight of octylphenol formaldehyde resin and 0.6 parts by weight of stannous chloride dihydrate in 0.5 parts by weight of 2,2,4-trimethylpentane. The crosslinking solution was then injected into the co-rotating twin-screw extruder in zone four using a high-pressure liquid metering pump.

[0085] In the eighth zone of the co-rotating twin-screw extruder, the vacuum pump is turned on to maintain the vacuum level of the exhaust section of the co-rotating twin-screw extruder at -0.085MPa for azeotropic devolatilization.

[0086] A 0.8mm thick galvanized steel strip is pressed into a corrugated shape using a roller pressing device. The surface of the galvanized steel strip is heated to 175℃ using a medium-frequency induction heating coil. The composite melt extruded from the die of a co-rotating twin-screw extruder is then wrapped onto the heated galvanized steel strip surface using a winding machine, and spirally overlapped at a winding speed of 5m / min to obtain the initial state pipe.

[0087] The initial state pipe is directly introduced into the circulating water bath cooling tank. A 28kHz frequency, 0.2W / cm² power density device is installed at the bottom of the rear section of the circulating water bath cooling tank. 2 The ultrasonic transducer, the initial state of the pipe is cooled to complete solidification in an ambient water temperature of 15℃ for 30 seconds, and then traction and fixed-length cutting are used to obtain a steel strip reinforced spiral cable protection pipe.

[0088] Example 5: This embodiment provides a method for preparing a steel strip reinforced spiral cable protection pipe, including the following steps: 70 parts by mass of block copolymer polypropylene, 5.5 parts by mass of ethylene-vinyl alcohol copolymer, 3 parts by mass of hydroxyl-terminated highly branched polyester prepared in Preparation Example 2, 8.5 parts by mass of ethylene-1-octene copolymer, 3 parts by mass of microcrystalline wax, and 6 parts by mass of electromagnetic rheological premixed masterbatch prepared in Preparation Example 7 were physically mixed, and the resulting mixture was fed into the main feed port of a co-rotating twin-screw extruder.

[0089] The temperature of the feeding and plasticizing section in zones one to three of the co-rotating twin-screw extruder is set to 180℃, the temperature of the homogenization and dynamic vulcanization section in zones four to seven of the co-rotating twin-screw extruder is set to 215℃, the temperature of the venting section in zone eight of the co-rotating twin-screw extruder is set to 210℃, and the temperature of the die section of the co-rotating twin-screw extruder is set to 205℃.

[0090] A crosslinking solution was prepared by dissolving 0.6 parts by weight of octylphenol formaldehyde resin and 0.6 parts by weight of stannous chloride dihydrate in 0.5 parts by weight of 2,2,4-trimethylpentane. The crosslinking solution was then injected into the co-rotating twin-screw extruder in zone four using a high-pressure liquid metering pump.

[0091] In the eighth zone of the co-rotating twin-screw extruder, the vacuum pump is turned on to maintain the vacuum level of the exhaust section of the co-rotating twin-screw extruder at -0.095MPa for azeotropic devolatilization.

[0092] A 0.8mm thick galvanized steel strip is pressed into a corrugated shape using a roller pressing device. The surface of the galvanized steel strip is heated to 185℃ using a medium-frequency induction heating coil. The composite melt extruded from the die of a co-rotating twin-screw extruder is then wrapped onto the heated galvanized steel strip surface using a winding machine, and spirally overlapped and wound at a winding speed of 15m / min to obtain the initial state pipe.

[0093] The initial state pipe is directly introduced into the circulating water bath cooling tank. A 28kHz frequency, 0.5W / cm² power density device is installed at the bottom of the rear section of the circulating water bath cooling tank. 2 The ultrasonic transducer, the initial state of the pipe is cooled to complete solidification in an ambient water temperature of 25℃ for 10 seconds, and then traction and fixed-length cutting are used to obtain a steel strip reinforced spiral cable protection pipe.

[0094] Comparative Examples 1-5: Comparative Example 1: Compared with Example 1, the difference is that ethylene-vinyl alcohol copolymer is not added, the hydroxyl-terminated highly branched polyester prepared in Preparation Example 2 is used, ethylene-1-octene copolymer, microcrystalline wax, electromagnetic rheology premixed masterbatch prepared in Preparation Example 7 is used, octylphenol formaldehyde resin, stannous chloride dihydrate, and 2,2,4-trimethylpentane are used, and 100 parts by weight of block copolymer polypropylene is directly fed into the main feed port of a co-rotating twin-screw extruder, and all other aspects are the same.

[0095] Comparative Example 2: Compared with Example 1, the difference is that no microcrystalline wax is added during the physical mixing process in step one, while the rest are the same.

[0096] Comparative Example 3: Compared with Example 1, the difference is that octylphenol formaldehyde resin, stannous chloride dihydrate and 2,2,4-trimethylpentane are not added in step one, the crosslinking solution is not injected into the fourth zone of the co-rotating twin-screw extruder, and the ethylene-1-octene copolymer is not subjected to dynamic vulcanization treatment. All other aspects are the same.

[0097] Comparative Example 4: Compared with Example 1, the difference is that 2,2,4-trimethylpentane is not used in step one. Octylphenol formaldehyde resin and stannous chloride dihydrate are directly fed as solid powder into zone four of the co-rotating twin-screw extruder. In addition, the vacuum pump is not turned on in zone eight of the co-rotating twin-screw extruder to maintain the internal air pressure of zone eight of the co-rotating twin-screw extruder at atmospheric pressure and no azeotropic devolatilization treatment is performed. All other aspects are the same.

[0098] Comparative Example 5: Compared with Example 1, the difference is that the hydroxyl-terminated highly branched polyester prepared in Preparation Example 2 is not added during the physical mixing process in step one; all other aspects are the same.

[0099] Test Examples 1-4: Test Example 1: Macroscopic Thermomechanical Analysis Test of Thermodynamic Internal Stress Energy Storage and Microcrystalline Wax Gating and Unlocking Mechanism This test case provides specific operational steps for macroscopic thermomechanical analysis testing: Using a low-speed precision cutting machine, rectangular test strips with a length of 10.0 mm, a width of 5.0 mm, and a thickness consistent with the original pipe wall thickness were cut from the flat area of ​​the pipes prepared in Examples 1 to 5 and Comparative Examples 1 to 5. The cut surfaces at both ends of the rectangular test strips were mechanically ground to ensure that the two ends of the rectangular test strips were parallel.

[0100] The rectangular test specimen is vertically mounted on the quartz sample stage of the thermomechanical analyzer. The flat-bottomed quartz expansion probe of the thermomechanical analyzer is lowered so that it is in complete contact with the top end face of the rectangular test specimen. The constant static preload applied by the flat-bottomed quartz expansion probe is set to 0.05N to ensure that the flat-bottomed quartz expansion probe and the rectangular test specimen are in close contact during the test and that no forced mechanical compression deformation occurs.

[0101] The heating furnace of the sealed thermomechanical analyzer is purged with high-purity nitrogen at a flow rate of 50 mL / min for atmosphere protection, and the air inside the heating furnace is purged for 10 minutes to remove all air from the furnace.

[0102] The temperature control program of the thermomechanical analyzer was set, the initial temperature of the heating furnace was set to 25℃ and held constant for 5 minutes, and then the internal temperature of the heating furnace was linearly increased from 25℃ to 120℃ at a fixed heating rate of 3℃ / min.

[0103] During the programmed heating process, a high-precision linear variable differential transformer displacement sensor inside the thermomechanical analyzer was used to collect and record the dimensional changes of the rectangular test specimen along its length in real time. After the test, the data processing software built into the thermomechanical analyzer was used to perform calculus calculations on the curves of the collected dimensional changes versus temperature, extracting the average linear expansion coefficient in the 25℃ to 60℃ range, the peak linear expansion coefficient in the 70℃ to 80℃ range, and the sudden increase in macroscopic transient dimensional strain triggered at a specific temperature point.

[0104] Table 1. Comparison of Macroscopic Thermal Expansion Parameters from Thermomechanical Analysis ; Conclusions and Analysis: According to Table 1, Figure 1 and Figure 2The data from Examples 1 to 5 show that the average linear expansion coefficients in the 25°C to 60°C ranged from 108.91 μm / (m·°C) to 116.35 μm / (m·°C), consistent with the basic thermal expansion physical characteristics of normal multiphase polyolefin alloy materials. When the temperature was raised to the region near the phase transformation point of 75°C set by the microcrystalline wax (between 70°C and 80°C), the peak linear expansion coefficients of Examples 1 to 5 showed a significant increase, with the highest abrupt change reaching 452.18 μm / (m·°C), accompanied by a sudden increase in dimensional strain of 1.35% to 2.11%. This physical volume expansion demonstrates that during the preparation process, the block copolymer polypropylene continuous phase matrix underwent a transformation from a molten state to a monoclinic crystal system. The accompanying thermodynamic volume contraction has successfully applied compressive stress to the internal ethylene-1-octene copolymer elastomer microparticles. When the furnace temperature reaches 75°C, the microcrystalline wax enriched around the interface of the elastic microparticles undergoes an endothermic phase change from a solid phase to a locally low-viscosity fluid. This releases the rigid steric hindrance imposed on the ethylene-1-octene copolymer by the block copolymer polypropylene matrix. The high-stress ellipsoidal ethylene-1-octene copolymer microparticles, now free from spatial constraints, instantly release their internally stored elastic potential energy and recover towards the sphere, resulting in isotropic volume expansion. This translates into an increase in the probe displacement of the thermomechanical analyzer under macroscopic testing. The above data verify the establishment of the linkage mechanism between thermodynamic internal stress pre-storage and microcrystalline wax phase change gating unlocking in engineering material systems.

[0105] Compared with the data of Comparative Example 1, pure block copolymer polypropylene maintained a smooth thermal expansion transition throughout the entire test temperature range, without any sudden increase in transient strain caused by stress release, which established that the sudden change in thermal expansion originated from the physical properties of the multiphase blend system rather than the substrate itself.

[0106] Compared with the data of Comparative Example 2, the peak linear expansion coefficient of the test sample without added microcrystalline wax in the 70℃ to 80℃ range was only 112.79 μm / (m·℃), which is almost the same as the linear expansion coefficient in the room temperature range. This objectively proves that even if the elastic potential energy of the ethylene-1-octene copolymer is stored in the system through rapid cooling and solidification, without the free volume generated by phase change melting provided by microcrystalline wax, it is impossible to release the rigid lattice constraint in the temperature range below the melting point of block copolymer polypropylene by simply relying on external heating. The elastic potential energy is in a physically locked state. The addition of microcrystalline wax and the phase change rheological unlocking mechanism are technically necessary.

[0107] Compared with the data of Comparative Example 3, the test sample without dynamic vulcanization treatment showed only a slight deformation of 0.28% at around 75℃. The ethylene-1-octene copolymer molecular chains that did not undergo chemical cross-linking to form a three-dimensional incompressible network structure underwent irreversible plastic slip deformation under the compressive stress generated by the crystallization shrinkage of the block copolymer polypropylene matrix. They could not convert mechanical stress into elastic deformation potential energy of polymer chain segments for storage. When the microcrystalline wax melted and the steric hindrance was relieved by heating, the uncross-linked ethylene-1-octene copolymer could not provide expansion recovery stress, which proved that the three-dimensional cross-linked network based on chemical bonds is a prerequisite for the occurrence of the physical kinetic energy storage mechanism.

[0108] In addition, since Comparative Examples 4 and 5 also possessed ethylene-1-octene copolymers with microcrystalline wax and dynamic vulcanization treatment, they still exhibited strain surge increment characteristics similar to those of the examples in macroscopic thermomechanical analysis tests. The above physical stress release verification data provides exclusive evidence to support the analysis of the overall repair failure of these two comparative examples due to chemical recombination failure in the subsequent tensile repair efficiency test.

[0109] Test Example 2: Test of Heating and Triggering Efficiency of Alternating Magnetic Field in Electromagnetic Transformer This test case provides specific operating procedures for testing the efficiency of alternating magnetic field-induced heating and triggering. Using a CNC precision cutting machine, square tube strips with a length of 50.0 mm and a width of 50.0 mm were cut from the tubes obtained in Examples 1 to 5 and Comparative Examples 1 to 5. A blind hole with a depth of 25.0 mm and a diameter of 1.0 mm was drilled at the center of the side of the square tube strip using a micro bench drill. The end of the blind hole was located at the geometric center of the resin layer inside the square tube strip.

[0110] The temperature of the environmental testing chamber was set to 25.0℃ and maintained at that temperature for 60 minutes to ensure that the initial internal temperature of the square tubular sample was completely balanced with the ambient temperature.

[0111] The alternating magnetic field generator equipped with a circulating water cooling system was placed in the environmental testing chamber. After applying thermal grease to the multi-channel high-precision K-type thermocouple probe, it was fully inserted into the blind hole of the square tubular template. Then, the square tubular template was fixed at the center of the induction coil of the alternating magnetic field generator.

[0112] Turn on the alternating magnetic field generator and set its output frequency to 50kHz and magnetic field strength to 30kA / m to simulate the alternating electromagnetic field environment generated during the operation of the ultra-high voltage cable.

[0113] The data acquisition recorder connected to the multi-channel high-precision K-type thermocouple probe is turned on, and the real-time temperature data inside the square tube sample is continuously recorded at a sampling frequency of 1Hz. After continuously applying an alternating magnetic field for 300s, the alternating magnetic field generator is turned off. The temperature time series data recorded by the data acquisition recorder is saved, and the time required to reach 75℃ and the highest equilibrium temperature within 300s are extracted.

[0114] Table 2. Comparison of Test Data on Induction Temperature Rise Inside Pipes under Alternating Magnetic Field Environment ; Conclusions and Analysis: According to Table 2, Figure 3 and Figure 4 According to the data, the time required for the internal temperature of the pipes prepared in Examples 1 to 5 to rise from an initial temperature of 25°C to 75°C under the action of an alternating magnetic field of 50kHz and 30kA / m is distributed between 112.5s and 158.2s, and the highest equilibrium temperature can be stabilized in the range of 82.1°C to 91.7°C within 300s.

[0115] The above data verifies that the electromagnetic rheological premixed masterbatch can achieve efficient internal heating by relying solely on the alternating magnetic field of the environment without any external direct heating source. The physical essence of the heat generation phenomenon lies in the fact that the surface-modified carbonyl iron powder in the electromagnetic rheological premixed masterbatch, as hard magnetic particles, undergoes repeated magnetic moment reversals in the alternating magnetic field, generating hysteresis loss. At the same time, polyisobutylene, as a high-viscosity rheological medium, allows the surface-modified carbonyl iron powder particles to undergo microscopic spatial rotation, resulting in rheological friction loss between particles and between particles and polyisobutylene molecular chains. The hysteresis loss and rheological friction loss are converted into heat energy, causing the internal temperature of the pipe to quickly break through the phase change melting temperature of microcrystalline wax (75°C). In Example 3, since the electromagnetic rheological premixed masterbatch was added in the largest amount (9 parts by mass), the time required for the internal temperature to rise to 75°C was the shortest, confirming that the induction heating rate is positively controlled by the concentration of the premixed masterbatch.

[0116] Compared with the data of Comparative Example 1, the pure block copolymer polypropylene pipe without the addition of electromagnetic rheological premix masterbatch does not have the ability to generate heat in the alternating magnetic field. The highest equilibrium temperature within 300s is only 25.5℃. The slight fluctuation of the ambient baseline temperature eliminates the interference of the alternating magnetic field generator's own heating on the temperature of the test sample. This proves that the completely insulated and non-magnetic block copolymer polypropylene skeleton is in a state of transmission to the alternating magnetic field. This clarifies that the local heating triggering mechanism depends entirely on the electromagnetic rheological phase added in this invention.

[0117] Observing the data of Comparative Examples 2 to 5, since Comparative Examples 2 to 5 also added electromagnetic rheological premixed masterbatch, the time required for the internal temperature to rise to 75°C and the highest equilibrium temperature within 300s were very close to those of Example 1. The temperature increase itself is not the purpose of self-repair, but a means of triggering physiological phase transition unlocking. Although Comparative Examples 2 to 5 were able to successfully reach the trigger temperature threshold of 75°C, in subsequent tests, due to the lack of microcrystalline wax (Comparative Example 2), the lack of pre-stored elastic kinetic energy (Comparative Example 3), or the damage to the chemical reorganization network (Comparative Examples 4 and 5), even if sufficient heat was generated, it was impossible to complete the mechanical closure and chemical healing of the microcracks in the pipe.

[0118] The test data establishes the feasibility of using electromagnetic rheological premixed masterbatch as an energy conversion hub. Combined with the gating settings of microcrystalline wax, it constructs the conditions for spontaneously starting the repair process based on the internal cable environment, thus overcoming the engineering application limitations of traditional thermoplastic self-healing materials that rely on external heating with a manual hot air gun.

[0119] Test Example 3: Initial Foundation Mechanical Property Test of Pipe This test example provides specific operational steps for testing the initial foundation mechanical properties of pipes: According to the national standard GB / T9647, pipe samples with a length of 300.0 mm were cut from the pipes prepared in Examples 1 to 5 and Comparative Examples 1 to 5. The pipe samples were placed between the upper and lower pressure plates of the microcomputer-controlled electronic universal testing machine. The constant compression speed of the microcomputer-controlled electronic universal testing machine was set to 10 mm / min. A compressive load was applied to the radial direction of the pipe samples. The load value corresponding to the vertical deformation of the inner diameter of the pipe samples reached 3% of the original inner diameter was recorded. The ring stiffness value of the pipe samples was calculated.

[0120] According to the industry-standard pipe peel test, peel test strips with a width of 20.0 mm and a length of 150.0 mm were cut from the pipes prepared in Examples 1 to 5 and Comparative Examples 1 to 5 along the spiral seam direction of the pipe surface. The resin layer and the galvanized steel strip layer of the peel test strip were manually peeled apart by 30.0 mm at the end. The ends of the resin layer and the galvanized steel strip layer were clamped in the upper and lower clamps of the electronic tensile testing machine. The tensile speed of the electronic tensile testing machine was set to 50 mm / min, and a 180-degree constant speed peel test was performed. The average peel force value during the stable peel stage was recorded. The average peel force value was divided by the width of the peel test strip to calculate the peel strength value between the resin layer and the galvanized steel strip layer.

[0121] According to national standard GB / T14152, impact test specimens with a length of 200.0 mm were cut from the pipes prepared in Examples 1 to 5 and Comparative Examples 1 to 5. The impact test specimens were placed in a constant temperature freezer at 0℃ for 24 hours for conditioning. After conditioning, the specimens were placed on the V-shaped bracket of a drop hammer impact testing machine. A fixed drop hammer with a mass of 1.0 kg and a punch radius of 12.5 mm was used to perform heavy hammer impact tests on the surface of the specimens from different heights. The step method was used to test and calculate the average value of the drop hammer impact energy absorbed, which caused 50% of the impact test specimens to undergo brittle fracture.

[0122] Table 3. Comparison of initial foundation mechanical properties of pipes ; Conclusions and Analysis: According to Table 3, Figure 5 , Figure 6 and Figure 7 According to the data, the ring stiffness of the pipes prepared in Examples 1 to 5 remained at 10.32 kN / m. 2 Up to 11.21 kN / m 2 Between these values, the average energy absorbed by the drop hammer impact at 0℃ ranges from 31.8J to 42.1J, and the peel strength between the resin layer and the galvanized steel strip layer ranges from 76.2N / cm to 95.8N / cm. These data indicate that after introducing a complex multiphase system containing ethylene-1-octene copolymer, ethylene-vinyl alcohol copolymer, microcrystalline wax, and electromagnetic rheological premixed masterbatch into the main continuous phase of block copolymer polypropylene, the pipe does not lose the necessary mechanical support capacity as an engineering cable protection pipe. On the contrary, it obtains low-temperature impact resistance and metal interface adhesion performance through multiphase blending modification.

[0123] Compared with the data in Comparative Example 1, the pure polyolefin pipe made from only 100 parts by mass of block copolymer polypropylene has a strength of 12.45 kN / m. 2 While achieving the highest rigidity index, the average energy absorbed by a drop hammer impact at 0°C is only 15.6 J, and the peel strength is only 42.3 N / cm. Pure block copolymer polypropylene exhibits significant low-temperature brittleness, and the adhesion between the non-polar macromolecular chains and the polar galvanized steel strip surface is poor. In this example, by adding ethylene-1-octene copolymer microparticles that have undergone dynamic vulcanization treatment, the high cross-linking density elastomer three-dimensional network dissipates the instantaneous impact energy applied externally, thereby improving the overall impact toughness of the pipe by more than 100%.

[0124] Compared with the data of Comparative Example 3, the average energy absorbed by the pipe without dynamic vulcanization crosslinking treatment of ethylene-1-octene copolymer decreased to 24.5J in the 0℃ environment of drop hammer impact damage. The molecular chains of ethylene-1-octene copolymer that have not formed a chemical bond crosslinking network underwent plastic slip or even molecular chain breakage when subjected to high-speed heavy hammer impact. They could not absorb a large amount of external energy through reversible elastic deformation like crosslinked elastomer particles. The test data proves that the dynamic vulcanization process of this invention not only serves the thermodynamic internal stress pre-storage mechanism, but also serves as a means to maintain the toughness of composite pipe and prevent pipe from breaking during use.

[0125] Compared with the data of Comparative Example 5, the peel strength of the pipe without the addition of terminal hydroxyl highly branched polyester decreased to 45.8 N / cm, which is at the same level as that of Comparative Example 1 without any modifier. The terminal hydroxyl highly branched polyester relies on the extremely high density of free polar hydroxyl groups carried on the periphery of the spherical molecular structure to establish physical adsorption and hydrogen bonding between the non-polar polyolefin continuous phase and the polar metal surface. The high density of terminal hydroxyl groups is not only responsible for chemical recombination with ethylene-vinyl alcohol copolymer during the self-repair stage of pipe damage, but also acts as an interfacial tackifier in the initial state of the pipe when it is intact. It is responsible for firmly anchoring the resin coating layer to the surface of the galvanized steel strip, preventing interlayer peeling damage when the pipe is under stress or bent and wound during service.

[0126] Based on the fundamental mechanical data from Examples 1 to 5, it can be seen that the multiphase linkage self-healing system constructed by the present invention has complete mechanical feasibility in practical engineering applications, and the formula design meets or even exceeds the basic physical boundary conditions of the pipe.

[0127] Test Example 4: Comparative Test of Macroscopic Self-Healing Efficiency After Damage This test case provides specific operational steps for a comparative test of macroscopic self-healing efficiency after damage: According to the national standard GB / T1040.2, standard type 1B dumbbell-shaped tensile test specimens were punched out from the flat area of ​​the pipe wall of the pipes prepared in Examples 1 to 5 and Comparative Examples 1 to 5 using a mechanical punching machine. The punched type 1B dumbbell-shaped tensile test specimens were divided into a non-destructive reference group, a damage treatment group A, and a damage treatment group B. Each group contained 5 parallel type 1B dumbbell-shaped tensile test specimens.

[0128] The type 1B dumbbell-shaped tensile test specimen of the non-destructive testing datum group was installed between the upper and lower clamps of the microcomputer-controlled electronic universal testing machine. The tensile speed of the microcomputer-controlled electronic universal testing machine was set to 50 mm / min for room temperature tensile testing. The average value of the initial tensile yield strength of the type 1B dumbbell-shaped tensile test specimen of the non-destructive testing datum group when it yielded was recorded.

[0129] Using a special tool equipped with a micrometer, a single-sided V-shaped surface microcrack with a depth of 0.5 mm was cut transversely along the direction perpendicular to the tensile direction in the narrow parallel section of the center of the 1B type dumbbell-shaped tensile test specimens of damage treatment group A and damage treatment group B, to simulate the penetrating scratches that the pipe is subjected to during service.

[0130] The type 1B dumbbell-shaped tensile test specimens of damage treatment group A were subjected to oven heating repair treatment. The type 1B dumbbell-shaped tensile test specimens of damage treatment group A were placed flat in a constant temperature drying oven at 75℃ and heated at a constant temperature for 30 minutes. They were then removed and cooled in an environment of 25℃ for 24 hours. The type 1B dumbbell-shaped tensile test specimens of damage treatment group B were subjected to induction heating repair treatment. The type 1B dumbbell-shaped tensile test specimens of damage treatment group B were placed at the center of the induction coil of an alternating magnetic field generator. The output frequency of the alternating magnetic field generator was set to 50kHz and the magnetic field strength to 30kA / m. The alternating magnetic field was continuously applied for 180s and then the alternating magnetic field generator was turned off. The type 1B dumbbell-shaped tensile test specimens of damage treatment group B were then cooled in an environment of 25℃ for 24 hours.

[0131] The repaired and cooled 1B dumbbell-shaped tensile test specimens of damage treatment group A and damage treatment group B were installed on a microcomputer-controlled electronic universal testing machine and subjected to room temperature tensile testing at a tensile speed of 50 mm / min. The average tensile yield strength after repair of damage treatment group A and damage treatment group B was recorded. The average tensile yield strength after repair was divided by the average initial tensile yield strength to calculate the corresponding tensile strength recovery rate.

[0132] Table 4. Comparison of Macroscopic Self-Healing Efficiency Test Data after Damage ; Conclusions and Analysis: According to Table 4, Figure 8 and Figure 9According to the data, the pipe samples prepared in Examples 1 to 5, after undergoing microcrack cutting damage with a depth of 0.5 mm, showed a tensile strength recovery rate of 81.87% to 93.16% regardless of whether a 75°C constant temperature drying oven was used to directly provide an ambient heat source (Treatment A) or an alternating magnetic field was used to induce heat inside the pipe through electromagnetic rheological premixed masterbatch (Treatment B). The test data confirmed the completeness and effectiveness of the multiphase phase change linkage microcrack self-healing mechanism proposed in this invention. When the trigger temperature of 75°C is reached, the microcrystalline wax undergoes a phase change and melts to generate free volume, thus releasing the block copolymer polypropylene matrix from the copolymerization of ethylene-1-octene. The steric hindrance lock-up effect applied by the elastomer causes the ethylene-1-octene copolymer microparticles under high stress to expand by releasing elastic potential energy, forcibly pushing and compressing the two sides of the microcrack to achieve physical closure. After the physical distance is reduced, the free polar hydroxyl groups on the terminal hydroxyl highly branched polyester molecular chain and the polar functional groups on the ethylene-vinyl alcohol copolymer chain segment reassociate at a very close distance to form a dense intermolecular hydrogen bond network, achieving chemical healing. The physical mechanism provides mechanical kinetic energy to close the crack, and the chemical mechanism provides thermodynamic binding force to solidify the crack. The two work together to complete the performance repair. In Example 3, due to the highest proportion of each functional phase added, the recovery rate reached the highest of 93.16%.

[0133] Compared with the data of Comparative Example 1, the tensile strength recovery rate of pure block copolymer polypropylene material after damage and treatment was only maintained at a low level of about 27%. The remaining strength was provided only by the unbroken resin layer at the bottom of the microcrack. The material itself could not undergo any spontaneous closure or healing reaction, which established the engineering vulnerability of traditional single polyolefins when faced with microcrack propagation.

[0134] Compared with the data of Comparative Example 2, the tensile strength recovery rate of the pipe without microcrystalline wax was only about 36% even when heated to 75°C or placed in an alternating magnetic field. Without the free volume provided by microcrystalline wax for phase change melting, the block copolymer polypropylene continuous phase matrix still maintained a completely rigid solid skeleton support state at 75°C. This rigid skeleton firmly blocked the ethylene-1-octene copolymer, and the elastic recovery potential energy stored in the ethylene-1-octene copolymer could not be released by overcoming the physical spatial steric hindrance. The two sides of the crack could not approach each other in terms of physical distance, which caused the subsequent hydrogen bond recombination chemical healing to completely lose the spatial distance basis. This verifies the necessity of the microcrystalline wax temperature gating unlocking mechanism as the first switch of the self-healing link.

[0135] Compared with the data of Comparative Example 3, the recovery rate of ethylene-1-octene copolymer pipes without dynamic vulcanization crosslinking treatment remained at around 42%. Because the ethylene-1-octene copolymer did not form a three-dimensional network with high crosslinking density, it could not resist the compressive stress caused by the crystallization shrinkage of the block copolymer polypropylene matrix during the extrusion cooling stage, thus causing irreversible plastic deformation. It could not convert the compressive stress into elastic potential energy to be pre-stored inside the material. When the microcrystalline wax melted and unlocked, the ethylene-1-octene copolymer, which did not have the energy storage state, could not generate volume expansion thrust, and the physical closure of the crack failed. This proves that the three-dimensional network based on chemical bond crosslinking is the material basis for providing self-healing mechanical kinetic energy.

[0136] Compared with the data of Comparative Example 4, the pipes that did not undergo azeotropic devolatilization treatment and were not injected with 2,2,4-trimethylpentane only achieved a tensile strength recovery rate of about 60%. Comparative Example 4, which has microcrystalline wax and dynamic vulcanized elastomer, can complete physical approach and closure. However, due to the failure to remove moisture from the system, the residual water molecules occupied a large number of free hydroxyl sites on the terminal hydroxyl highly branched polyester. This caused the ethylene-vinyl alcohol copolymer segments to be unable to form a sufficiently dense hydrogen bond network with the polar hydroxyl groups occupied by water. As a result, although the cracks were closed, they were not strong and immediately reopened after slight stretching. This confirms that the exclusion of moisture to compete for hydroxyl sites is a mandatory chemical boundary condition to ensure the strength of chemical healing.

[0137] Compared with the data of Comparative Example 5, the tensile strength recovery rate of the pipe without the addition of terminal hydroxyl highly branched polyester remained at about 55%. Comparative Example 5 could also complete the physical closure action, but it completely lacked the chemical crosslinking hub that provides high density terminal hydroxyl groups. The macromolecular chain segments at the microcrack interface lacked sufficient chemical association force and could not resist secondary stretching. Combining the data of Comparative Examples 2 to 5, as long as any one of the four links of crystallization volume shrinkage energy storage, temperature gating unlocking, elastic expansion closure, and mesoscopic hydrogen bond recombination is missing, the macroscopic self-healing efficiency of the pipe will decrease. This demonstrates that the linkage system of the present invention is a closed loop of mutual intervention and mutual synergy.

Claims

1. A method of manufacturing a steel belt reinforced, coiled cable protection pipe, characterized in that, Includes the following steps: Block copolymer polypropylene, ethylene-vinyl alcohol copolymer, hydroxyl-terminated highly branched polyester, ethylene-1-octene copolymer, microcrystalline wax and electromagnetic rheology premixed masterbatch are physically mixed to obtain a mixture, and the mixture is fed into the main feed port of a co-rotating twin-screw extruder. The co-rotating twin-screw extruder is subjected to programmed temperature rise, a crosslinking solution is injected into the middle section of the co-rotating twin-screw extruder to perform dynamic vulcanization treatment of the ethylene-1-octene copolymer, a vacuum pump is turned on in the exhaust section of the co-rotating twin-screw extruder to perform azeotropic devolatilization, and the composite melt is extruded through the die of the co-rotating twin-screw extruder. Galvanized steel strip is pressed into a corrugated shape, and the surface of the galvanized steel strip is heated by a medium-frequency induction heating coil. The composite melt is then wrapped around the heated surface of the galvanized steel strip and spirally overlapped to obtain the initial state pipe. The initial state pipe is introduced into a circulating water bath cooling tank equipped with ultrasonic transducers for cooling and solidification. After traction and fixed-length cutting, a steel strip reinforced spiral cable protection pipe is obtained.

2. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The material ratio range for the physical mixing is: 60-80 parts by weight of the block copolymer polypropylene, 3-8 parts by weight of the ethylene-vinyl alcohol copolymer, 1-5 parts by weight of the hydroxyl-terminated highly branched polyester, 5-12 parts by weight of the ethylene-1-octene copolymer, 1-5 parts by weight of the microcrystalline wax, and 4.5-9 parts by weight of the electromagnetic rheology premixed masterbatch.

3. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The co-rotating twin-screw extruder includes a feeding and plasticizing section in zones one to three, a homogenization and dynamic vulcanization section in zones four to seven, a venting section in zone eight, and a die section. The crosslinking solution is injected into zone four of the homogenization and dynamic vulcanization sections in zones four to seven.

4. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 3, characterized in that, The temperature of the feeding and plasticizing sections in zones one to three of the co-rotating twin-screw extruder is set to 165–180°C. The temperature of the homogenization and dynamic vulcanization zones four to seven of the co-rotating twin-screw extruder is set to 205–215°C. The temperature of the eighth-zone exhaust section of the co-rotating twin-screw extruder is set to 200–210°C. The temperature of the die section of the co-rotating twin-screw extruder is set to 195–205°C. The vacuum level of the eight-zone exhaust section of the co-rotating twin-screw extruder is maintained at -0.085 to -0.095 MPa.

5. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The crosslinking solution is composed of 0.3 to 1.0 parts by weight of octylphenol formaldehyde resin, 0.3 to 1.0 parts by weight of stannous chloride dihydrate, and 0.3 to 0.8 parts by weight of 2,2,4-trimethylpentane.

6. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The preparation steps of the terminal hydroxyl highly branched polyester include: In a reactor equipped with a mechanical stirrer, a nitrogen inlet device, and a water separator, 1-2 mol of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, 15-20 mol of 2,2-bis(hydroxymethyl)propionic acid, and 0.2-0.4 wt% of p-toluenesulfonic acid, representing 0.2-0.4 wt% of the total mass of the 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and the 2,2-bis(hydroxymethyl)propionic acid, are added. Under nitrogen protection, the reactor is heated to 120-140°C to carry out an esterification reaction for 2-3 hours. After the water generated by the esterification reaction is collected by the water separator, the internal pressure of the reactor is evacuated to -0.09 to -0.095 MPa and the melt polycondensation reaction is continued at 120-140°C for 3-5 hours. The reaction vessel was cooled to 20-30°C, the polycondensation product was extracted, and the polycondensation product was dissolved in acetone. The product was then purified by ice-water precipitation and vacuum dried to obtain a hydroxyl-terminated highly branched polyester.

7. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The electromagnetic rheological premixed masterbatch is prepared by mixing polyisobutylene with surface-modified carbonyl iron powder; the preparation steps of the surface-modified carbonyl iron powder include: 100-120 parts by weight of raw carbonyl iron powder are dispersed in a mixed solvent consisting of 400-500 parts by weight of anhydrous ethanol and 40-60 parts by weight of deionized water, and the pH of the mixed solvent is adjusted to 4.0-4.5 using glacial acetic acid. Add 1.5 to 3.0 parts by weight of γ-methacryloxypropyltrimethoxysilane to the mixed solvent, place the mixed solvent in a constant temperature water bath at 50 to 70°C, and mechanically stir the mixed solvent at a speed of 200 to 400 rpm for 2 to 4 hours. After the reaction was completed, the mixed solvent was treated with a centrifuge and the solid product was extracted. The solid product was washed three times with anhydrous ethanol and then dried in a vacuum oven at 70-90°C for 10-14 hours to obtain surface-modified carbonyl iron powder.

8. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 7, characterized in that, The preparation steps of the electromagnetic rheological premixed masterbatch include: 15-25 parts by weight of the polyisobutylene and 10 parts by weight of the surface-modified carbonyl iron powder are fed into an internal mixer. The working temperature of the internal mixer is set to 70-90°C and the rotation speed of the internal mixer is set to 30-50 rpm. The polyisobutylene and the surface-modified carbonyl iron powder were subjected to low-shear intensive mixing for 10-20 minutes. After mixing, the mixture was discharged and naturally cooled at 20-30°C to obtain electromagnetic rheological premixed masterbatch.

9. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The thickness of the galvanized steel strip is 0.6 to 1.2 mm. The surface of the galvanized steel strip is heated to 175 to 185°C, and the spiral lap winding speed is set to 5 to 15 m / min.

10. The method for preparing the steel strip reinforced wound cable protection pipe according to claim 1, characterized in that, The frequency of the ultrasonic vibrator is set to 25-30 kHz, the power density of the ultrasonic vibrator is set to 0.2-0.5 W / cm 2 ; the ambient water temperature of the circulating water bath cooling tank is set to 15-25℃, and the initial-state pipe is cooled to complete solidification in the circulating water bath cooling tank for 10-30 s.

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