Corrosion-resistant double armored submarine cable and preparation method thereof

Abstract

The application discloses a kind of corrosion-resistant double-armored submarine cable and preparation method thereof, it is related to submarine cable technical field.The corrosion-resistant double-armored submarine cable includes outer sheath layer, water barrier layer, double-armored layer, insulating inner liner, filling layer, insulating layer, copper conductor in turn from surface to inside;The outer sheath layer is obtained by extruding coating on the surface of double-armored layer by corrosion-resistant submarine cable material;The corrosion-resistant submarine cable material includes the following raw material components: by mass parts, 75-90 parts of high-density polyethylene, 30-50 parts of ultra-high molecular weight polyethylene, 10-25 parts of modified microfiber, 8-15 parts of ethylene-vinyl acetate copolymer, 0.2-0.5 parts of antioxidant, 1-1.2 parts of lubricant.The application optimizes sheath layer material, solves the problems of existing double-armored submarine cable corrosion failure, short service life, unstable performance and other problems, meets the demand of long-term service reliability.

Description

Technical Field

[0001] This invention relates to the field of submarine cable technology, specifically a corrosion-resistant double-armored submarine cable and its preparation method. Background Technology

[0002] With the rapid development of global marine resources, the large-scale construction of offshore wind power, and the advancement of transoceanic communication projects, submarine cables (hereinafter referred to as submarine cables), as the core carriers for marine power transmission and signal connectivity, are facing increasingly harsh service environments, and the requirements for service life, mechanical performance, and corrosion resistance are constantly increasing. Because submarine cables are buried in seabed sediment or suspended in seawater for long periods of time, they must continuously withstand multiple complex effects, including mechanical stresses such as deep-sea hydrostatic pressure, ocean current impact, and friction from seabed reefs, as well as multiple corrosive effects such as electrochemical corrosion, chemical degradation, and microbial erosion caused by high salinity and high humidity. At the same time, they must also resist the aging and damage to the sheath material caused by ultraviolet radiation from the sea surface. Their service reliability directly determines the stable operation and safety of marine engineering projects.

[0003] Currently, in the protective structure of submarine cables, the armor layer is the core that ensures their mechanical performance. Double-armored structures, due to their excellent tensile, compressive, impact, and mechanical puncture resistance, are widely used in submarine cable designs for complex marine environments such as the mid-deep sea and strong currents. Existing double-armored submarine cables typically use two layers of twisted metal wires or wrapped metal strips for the armor layer. The metal wires or strips of the two armor layers are arranged at different angles and directions along the cable's axis, effectively preventing further damage to the internal structure of the cable after sharp objects penetrate, thus enhancing the cable's mechanical protection capabilities. However, in actual service, existing double-armored submarine cables still face prominent problems such as sheath failure, severely shortening the cable's service life and increasing maintenance costs and safety risks in marine engineering projects.

[0004] To address the corrosion resistance issue of submarine cables, existing technologies modify the sheath material by adding inorganic fillers such as calcium carbonate and talc to improve its mechanical properties and corrosion resistance. However, traditional filler modification often involves simple filling, resulting in poor interfacial bonding with the polyolefin matrix and a tendency for filler agglomeration. This makes it difficult to significantly improve the sheath's impermeability and may even cause the sheath material to become brittle, affecting its mechanical toughness.

[0005] In summary, there is an urgent need to develop a corrosion-resistant double-armored submarine cable to solve the problems of corrosion failure, short lifespan, and unstable performance of existing double-armored submarine cables, and to meet the requirements for long-term service reliability. Summary of the Invention

[0006] The purpose of this invention is to provide a corrosion-resistant double-armored submarine cable and its preparation method, so as to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing a corrosion-resistant double-armored submarine cable includes the following preparation steps: S1: Twisting and pressing copper wires together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the insulating liner and the insulating layer with foamed material to form a filler layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer, resulting in a corrosion-resistant double-armored submarine cable.

[0008] Preferably, the corrosion-resistant submarine cable material comprises the following raw material components: by weight, 75-90 parts high-density polyethylene, 30-50 parts ultra-high molecular weight polyethylene, 10-25 parts modified microfiber, 8-15 parts ethylene-vinyl acetate copolymer, 0.2-0.5 parts antioxidant, and 1-1.2 parts lubricant.

[0009] Preferably, the preparation steps of the corrosion-resistant submarine cable material are as follows: after weighing the raw materials according to the mass parts, high-density polyethylene, ultra-high molecular weight polyethylene, ethylene-vinyl acetate copolymer, modified microfiber, antioxidant and lubricant are placed in a mixer and mixed at 140-160℃ and 30-50 r / min. After mixing for 10-15 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. Preferably, the preparation steps of the modified microfibers are as follows: polyethylene terephthalate, high-density polyethylene, and maleic anhydride-grafted ethylene-octene copolymer are dried, mixed, and extruded to obtain coarse particles; the coarse particles are pulverized and drawn into fibers using a granulator, then dried in a cold water bath and sheared to obtain microfibers; the microfibers are ultrasonically treated in anhydrous ethanol for 40-60 minutes, dried, and then immersed in a dopamine hydrochloride solution. The pH of the solution is adjusted to 8.5 using Tris buffer solution, stirred for 24 hours, washed, and dried to obtain polydopamine-microfibers; the polydopamine-microfibers are immersed in a calcium chloride solution and placed separately from the ammonium bicarbonate solution in the same sealed container for gas mineralization to obtain calcium carbonate-coated microfibers; the calcium carbonate-coated microfibers are mixed with a functionalized borate ester coupling agent and reacted at 100-120℃ for 20-30 minutes to obtain modified microfibers; More preferably, the coarse particles include the following raw material components: by weight, 10-20 parts polyethylene terephthalate, 75-85 parts high-density polyethylene, and 5-10 parts maleic anhydride-grafted ethylene-octene copolymer. Preferably, the process parameters for mixed extrusion are: extrusion zone temperature of 195-205℃, 220-230℃, 245-255℃, 260-270℃, 245-255℃, and rotation speed of 100 rpm; Preferably, the average diameter of the microfibers is 1-3 μm and the length is 3-5 mm; The preferred process parameters for gas mineralization are: a calcium chloride solution concentration of 0.05-0.1 mol / L, a calcium-magnesium ratio of (1.5-2):1, a pH of 8-9, a temperature of 70-80℃, and a time of 16-24 h. Preferably, the amount of functionalized borate coupling agent is 1-3 wt% of the calcium carbonate-coated microfibers.

[0010] Preferably, the preparation steps of the functionalized borate ester coupling agent are as follows: s1: Dissolve cyanuric chloride and anhydrous sodium carbonate in toluene, add a toluene solution containing long-chain amines at -5~0℃, react for 3-4 hours, filter under reduced pressure and concentrate, dry and dissolve in acetone solution, add acetone solution containing short-chain amines at 30-35℃, adjust pH to 6-7, react for 2-4 hours, filter, wash filter cake and dry to obtain product A; s2: Diethanolamine and boric acid were placed in toluene, heated to 115-120℃ under nitrogen atmosphere, refluxed for 2 hours to remove water, cooled, phenol was added, refluxed for 8 hours to remove water, cooled, and then purified by vacuum distillation to remove toluene to obtain product B. s3: Product A and product B, along with anhydrous sodium carbonate, were placed in anhydrous N,N-dimethylformamide and heated to 130℃ for 8-10 hours. The mixture was then filtered, the filter cake was washed, and the functionalized borate ester coupling agent was obtained.

[0011] More preferably, the long-chain amine in s1 is any one of dodecylamine, hexadecylamine, and octadecylamine; and the short-chain amine is any one of ethylenediamine, butanediamine, and hexamethylenediamine. Product A comprises the following raw material components: 15-20 parts cyanuric chloride, 16.5-22 parts long-chain amine, and 2.2-3 parts short-chain amine; The mass ratio of product A to product B in s3 is (5-7):1.

[0012] Preferably, the water-blocking buffer layer is obtained by wrapping semi-conductive non-woven fabric tape with an overlap rate of 20-25%; Preferably, the filler is an ethylene-vinyl acetate copolymer foam filler with a density of 80-90 kg / m³. 3 ; Preferably, the double armor layer is obtained by double-layer reverse twisting of galvanized steel wire; Compared with the prior art, the beneficial effects achieved by the present invention are: 1. This invention employs galvanized steel wire for double-layer armoring. Reverse twisting balances the torsional stress of the submarine cable during bending, reducing the risk of localized stress concentration in a single-layer armor. The water-blocking layer uses overlapping semi-conductive non-woven fabric tape, exhibiting excellent water-blocking performance, breathability, and flexibility. It tightly adheres to the surface of the double armor layer, effectively preventing seawater penetration. The filling layer uses ethylene-vinyl acetate copolymer (EVA) foam material, which possesses excellent buffering performance, flexibility, and interfacial compatibility. It fills the gap between the insulation layer and the inner insulation liner, dispersing the static pressure of deep-sea water and preventing the insulation layer from breaking due to excessive pressure. The outermost sheath layer uses corrosion-resistant submarine cable material with high-density polyethylene, ultra-high molecular weight polyethylene, and ethylene-vinyl acetate copolymer as the main base material, supplemented with modified microfibers and other auxiliary materials. The synergistic effect of these materials achieves a balanced improvement in performance. 2. The modified microfibers prepared in this invention are obtained by extruding and drawing high-density polyethylene reinforced with polyethylene terephthalate (PET), followed by dopamine coating, gas mineralization, and modification with a borate ester coupling agent. The polymer-synthesized microfibers serve as a high-strength skeleton, and a rough structure is constructed on their surface through polydopamine coating and mineralization. This calcium carbonate coating further enhances the seawater barrier effect and improves the seawater corrosion resistance of the sheath layer. A specific coupling agent material is then synthesized, which can react with borate esters and calcium carbonate... 3+ Coordination enables tight bonding with calcium carbonate-coated microfibers, while the long alkyl chain is exposed on the surface of the modified microfibers, forming a hydrophobic layer that further improves the dispersibility between materials. In addition, the long alkyl chain can achieve chemical bonding and physical entanglement with the host substrate, enhancing interfacial adhesion. The short-chain amine acts as a linker, connecting the two triazine rings. The length of the short-chain amine affects the rigidity and flexibility of the middle segment of the skeleton, which can be adjusted by combining it with the long-chain amine. Finally, the ultraviolet absorption properties of the triazine ring, benzene ring, etc., of this coupling agent can cope with long-term service. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0014] It should be noted that the following quantities are by weight, and there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include: The water-blocking buffer layer is made of a 200μm thick semi-conductive non-woven fabric tape with an overlap rate of 20%; the tensile strength of the semi-conductive non-woven fabric tape is 43N / cm, the elongation is 12%, and the surface resistance is 1500Ω. The filler is EVA foam with a density of 80 kg / m³. 3 ; Both the insulation layer and the insulation liner are made of EPDM rubber, with a volume resistivity of 2×10⁻⁶ at 20℃. 15 Ω·cm; The double armor layer is made of galvanized steel wire with a diameter of 2.5mm twisted in two reverse directions; The high-density polyethylene is designated as type 5000S; the ultra-high molecular weight polyethylene has a relative molecular mass of 2 million; the ethylene-vinyl acetate copolymer is designated as type 7470M; the maleic anhydride-grafted ethylene-octene copolymer has a grafting rate of 1.0-1.5% and a density of 0.89 g / cm³. 3 The antioxidant is 702; the lubricant is polyethylene wax. The preparation steps of functionalized borate ester coupling agents are as follows: s1: Dissolve 18.4 parts of cyanuric chloride and 11 parts of anhydrous sodium carbonate in 500 parts of toluene. Add a toluene solution containing 29.6 parts of octadecylamine at -5℃. After reacting for 4 hours, filter and concentrate under reduced pressure. After drying, dissolve in 500 parts of acetone. Add an acetone solution containing 1.2 parts of hexamethylenediamine at 35℃. Adjust the pH to 7. After reacting for 4 hours, filter, wash the filter cake, and dry to obtain product A. s2: 2.6 parts of diethanolamine and 1.6 parts of boric acid were placed in 50 parts of toluene. Under a nitrogen atmosphere, the mixture was heated to 120°C and refluxed to remove water for 2 hours. After cooling, 7.2 parts of phenol were added and refluxed to remove water for 8 hours. After cooling, the toluene was removed by vacuum distillation and purified to obtain product B. s3: 12 parts of product A, 2 parts of product B, and 2 parts of anhydrous sodium carbonate were placed in 150 parts of anhydrous N,N-dimethylformamide. The mixture was heated to 130℃ and reacted for 10 h. The mixture was then filtered, the filter cake was washed, and the functionalized borate ester coupling agent was obtained.

[0015] In the following examples, parts refer to parts by weight, and all raw materials mentioned above and others not mentioned are commercially available.

[0016] Example 1: This example provides a method for preparing a corrosion-resistant double-armored submarine cable, specifically including the following preparation steps: S1: Twist and press 7 copper wires with a diameter of 0.5mm together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer with a thickness of 1 mm; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the 1mm thick insulating liner and the insulating layer with foam material to form a 0.5mm thick filling layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer with a thickness of 3mm, thus obtaining a corrosion-resistant double-armored submarine cable. The preparation steps of the corrosion-resistant submarine cable material are as follows: After weighing the raw materials according to the mass parts, 85 parts of high-density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of modified microfiber, 10 parts of ethylene-vinyl acetate copolymer, 0.2 parts of antioxidant, and 1.0 parts of lubricant are placed in a mixer and mixed at 140℃ and 30r / min. After mixing for 15 minutes, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. The preparation steps of the modified microfibers are as follows: 15 parts of polyethylene terephthalate, 80 parts of high-density polyethylene, and 8 parts of maleic anhydride-grafted ethylene-octene copolymer are dried and then mixed and extruded at 100 rpm. The extrusion zone temperatures are 195℃, 220℃, 250℃, 260℃, and 250℃ to obtain coarse particles. The coarse particles are then pulverized and drawn into fibers using a granulator, followed by cold water bath drying and shearing to obtain microfibers with an average diameter of 3 μm and a length of 3 mm. The microfibers are then ultrasonically treated in anhydrous ethanol for 50 min and dried. Polydopamine-microfibers were obtained by immersing the microfibers in a 4.5 g / L dopamine hydrochloride solution, adjusting the pH to 8.5 with Tris buffer, stirring for 24 h, washing and drying. The polydopamine-microfibers were then immersed in a 0.1 mol / L calcium chloride solution and placed separately from a 0.1 mol / L ammonium bicarbonate solution in a sealed container for gas mineralization to obtain calcium carbonate-coated microfibers. The calcium carbonate-coated microfibers were then mixed with a functionalized borate ester coupling agent and reacted at 100 °C for 20 min to obtain modified microfibers. The process parameters for gas mineralization are: Ca 2+ / Mg 2+ The ratio was 1.5:1, the pH was 8.5, the temperature was 80℃, and the time was 24h; the amount of functionalized borate ester coupling agent accounted for 1 wt% of calcium carbonate-coated microfibers.

[0017] Example 2: This example provides a method for preparing a corrosion-resistant double-armored submarine cable, specifically including the following preparation steps: S1: Twist and press 7 copper wires with a diameter of 0.5mm together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer with a thickness of 1 mm; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the 1mm thick insulating liner and the insulating layer with foam material to form a 0.5mm thick filling layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer with a thickness of 3mm, thus obtaining a corrosion-resistant double-armored submarine cable. The preparation steps of the corrosion-resistant submarine cable material are as follows: After weighing the raw materials according to the mass parts, 85 parts of high-density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of modified microfiber, 10 parts of ethylene-vinyl acetate copolymer, 0.2 parts of antioxidant, and 1.0 parts of lubricant are placed in a mixer and mixed at 150°C and 50 r / min. After mixing for 10 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. The preparation steps of the modified microfibers are as follows: 20 parts of polyethylene terephthalate, 70 parts of high-density polyethylene, and 10 parts of maleic anhydride-grafted ethylene-octene copolymer are dried and then mixed and extruded at 100 rpm. The extrusion zone temperatures are 200℃, 220℃, 250℃, 260℃, and 250℃ to obtain coarse particles. The coarse particles are then pulverized and drawn into fibers using a granulator. After being dried in a cold water bath, the fibers are sheared to obtain microfibers with an average diameter of 3 μm and a length of 3 mm. The microfibers are then ultrasonically treated in anhydrous ethanol for 60 min and then dried. The microfibers were then immersed in a 4.5 g / L dopamine hydrochloride solution, and the pH of the solution was adjusted to 8.5 using Tris buffer. After stirring for 24 h, the microfibers were washed and dried to obtain polydopamine-microfibers. The polydopamine-microfibers were then immersed in a 0.1 mol / L calcium chloride solution and placed separately from the 0.1 mol / L ammonium bicarbonate solution in a sealed container for gas mineralization to obtain calcium carbonate-coated microfibers. The calcium carbonate-coated microfibers were then mixed with a functionalized borate ester coupling agent and reacted at 110 °C for 30 min to obtain modified microfibers. The process parameters for gas mineralization are: Ca 2+ / Mg 2+ The ratio was 2:1, the pH was 8.5, the temperature was 80℃, and the time was 16h; the amount of functionalized borate ester coupling agent accounted for 2wt% of the calcium carbonate coated microfibers.

[0018] Example 3: This example provides a method for preparing a corrosion-resistant double-armored submarine cable, specifically including the following preparation steps: S1: Twist and press 7 copper wires with a diameter of 0.5mm together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer with a thickness of 1 mm; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the 1mm thick insulating liner and the insulating layer with foam material to form a 0.5mm thick filling layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer with a thickness of 3mm, thus obtaining a corrosion-resistant double-armored submarine cable. The preparation steps of the corrosion-resistant submarine cable material are as follows: after weighing the raw materials according to the mass parts, 85 parts of high-density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of modified microfiber, 10 parts of ethylene-vinyl acetate copolymer, 0.2 parts of antioxidant, and 1.0 parts of lubricant are mixed at 160℃ and 50 r / min. After mixing for 10 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. The preparation steps of the modified microfibers are as follows: 20 parts of polyethylene terephthalate, 80 parts of high-density polyethylene, and 10 parts of maleic anhydride-grafted ethylene-octene copolymer are dried and then mixed and extruded at 100 rpm. The extrusion zone temperatures are 200℃, 230℃, 250℃, 270℃, and 250℃ to obtain coarse particles. The coarse particles are then pulverized and drawn into fibers using a granulator. After being dried in a cold water bath, the fibers are sheared to obtain microfibers with an average diameter of 3 μm and a length of 3 mm. The microfibers are then ultrasonically treated in anhydrous ethanol for 50 min and then dried. The microfibers were then immersed in a 4.5 g / L dopamine hydrochloride solution, and the pH of the solution was adjusted to 8.5 using Tris buffer. After stirring for 24 h, the microfibers were washed and dried to obtain polydopamine-microfibers. The polydopamine-microfibers were then immersed in a 0.1 mol / L calcium chloride solution and placed separately from the 0.1 mol / L ammonium bicarbonate solution in a sealed container for gas mineralization to obtain calcium carbonate-coated microfibers. The calcium carbonate-coated microfibers were then mixed with a functionalized borate ester coupling agent and reacted at 100 °C for 20 min to obtain modified microfibers. The process parameters for gas mineralization are: Ca 2+ / Mg 2+ The ratio was 2:1, the pH was 8.5, the temperature was 80℃, and the time was 24h; the amount of functionalized borate ester coupling agent accounted for 3wt% of the calcium carbonate coated microfibers.

[0019] Comparative Example 1: As a control experiment for Example 3, the difference is that the functionalized borate ester coupling agent was replaced with the commercially available silane coupling agent KH550, including the following steps: S1: Twist and press 7 copper wires with a diameter of 0.5mm together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer with a thickness of 1 mm; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the 1mm thick insulating liner and the insulating layer with foam material to form a 0.5mm thick filling layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer with a thickness of 3mm, thus obtaining a corrosion-resistant double-armored submarine cable. The preparation steps of the corrosion-resistant submarine cable material are as follows: after weighing the raw materials according to the mass parts, 85 parts of high-density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of modified microfiber, 10 parts of ethylene-vinyl acetate copolymer, 0.2 parts of antioxidant, and 1.0 parts of lubricant are mixed at 160℃ and 50 r / min. After mixing for 10 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. The preparation steps of the modified microfibers are as follows: 20 parts of polyethylene terephthalate, 80 parts of high-density polyethylene, and 10 parts of maleic anhydride-grafted ethylene-octene copolymer are dried and then extruded at 100 rpm under extrusion zone temperatures of 200℃, 230℃, 250℃, 270℃, and 250℃ to obtain coarse particles. These coarse particles are then pulverized and drawn into fibers using a granulator, followed by cold water bath drying and shearing to obtain microfibers with an average diameter of 3 μm and a length of 3 mm. The microfibers are then ultrasonically treated in anhydrous ethanol for 50 min, dried, and then immersed in a solution with a mass concentration of 4.5 g / L. In a dopamine hydrochloride solution, the pH was adjusted to 8.5 using Tris buffer, and after stirring for 24 h, the solution was washed and dried to obtain polydopamine-microfibers. The polydopamine-microfibers were then immersed in a 0.1 mol / L calcium chloride solution and placed separately from a 0.1 mol / L ammonium bicarbonate solution in a sealed container for gas mineralization to obtain calcium carbonate-coated microfibers. The calcium carbonate-coated microfibers were then dispersed in anhydrous ethanol, and an ethanol solution containing silane coupling agent KH550 at pH 4 was added. After stirring at 65 °C for 50 min, the mixture was filtered, washed, and dried to obtain modified microfibers. The process parameters for gas mineralization are: Ca 2+ / Mg 2+ The ratio was 2:1, the pH was 8.5, the temperature was 80℃, and the time was 24h; the amount of KH550 used accounted for 3wt% of the calcium carbonate-coated microfibers.

[0020] Comparative Example 2: As a control experiment for Example 3, the difference is that the modified microfibers were replaced with modified calcium carbonate, including the following steps: S1: Twist and press 7 copper wires with a diameter of 0.5mm together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer with a thickness of 1 mm; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the 1mm thick insulating liner and the insulating layer with foam material to form a 0.5mm thick filling layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer with a thickness of 3mm, thus obtaining a corrosion-resistant double-armored submarine cable. The preparation steps of the corrosion-resistant submarine cable material are as follows: after weighing the raw materials according to the mass parts, 85 parts of high-density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of modified calcium carbonate, 10 parts of ethylene-vinyl acetate copolymer, 0.2 parts of antioxidant, and 1.0 parts of lubricant are mixed at 160℃ and 50 r / min. After mixing for 10 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. The preparation steps of modified calcium carbonate are as follows: calcium carbonate is mixed with functionalized borate ester coupling agent and reacted at 100℃ for 20 min to obtain modified microfibers; the amount of functionalized borate ester coupling agent is 3 wt% of calcium carbonate.

[0021] Comparative Example 3: As a control experiment for Example 3, the difference is that the octadecylamine in the functionalized borate ester coupling agent was replaced with octylamine, including the following steps: S1: Twist and press 7 copper wires with a diameter of 0.5mm together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer with a thickness of 1 mm; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the 1mm thick insulating liner and the insulating layer with foam material to form a 0.5mm thick filling layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer with a thickness of 3mm, thus obtaining a corrosion-resistant double-armored submarine cable. The preparation steps of the corrosion-resistant submarine cable material are as follows: after weighing the raw materials according to the mass parts, 85 parts of high-density polyethylene, 40 parts of ultra-high molecular weight polyethylene, 20 parts of modified microfiber, 10 parts of ethylene-vinyl acetate copolymer, 0.2 parts of antioxidant, and 1.0 parts of lubricant are mixed at 160℃ and 50 r / min. After mixing for 10 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material. The preparation steps of the modified microfibers are as follows: 20 parts of polyethylene terephthalate, 80 parts of high-density polyethylene, and 10 parts of maleic anhydride-grafted ethylene-octene copolymer are dried and then mixed and extruded at 100 rpm. The extrusion zone temperatures are 200℃, 230℃, 250℃, 270℃, and 250℃ to obtain coarse particles. The coarse particles are then pulverized and drawn into fibers using a granulator. After being dried in a cold water bath, the fibers are sheared to obtain microfibers with an average diameter of 3 μm and a length of 3 mm. The microfibers are then ultrasonically treated in anhydrous ethanol for 50 min and then dried. The microfibers were then immersed in a 4.5 g / L dopamine hydrochloride solution, and the pH of the solution was adjusted to 8.5 using Tris buffer. After stirring for 24 h, the microfibers were washed and dried to obtain polydopamine-microfibers. The polydopamine-microfibers were then immersed in a 0.1 mol / L calcium chloride solution and placed separately from the 0.1 mol / L ammonium bicarbonate solution in a sealed container for gas mineralization to obtain calcium carbonate-coated microfibers. The calcium carbonate-coated microfibers were then mixed with a functionalized borate ester coupling agent and reacted at 100 °C for 20 min to obtain modified microfibers. The process parameters for gas mineralization are: Ca 2+ / Mg 2+ The ratio was 2:1, pH was 8.5, temperature was 80℃, and time was 24h; the amount of functionalized borate ester coupling agent accounted for 3wt% of the calcium carbonate-coated microfibers. The preparation steps of functionalized borate ester coupling agents are as follows: s1: Dissolve 18.4 parts of cyanuric chloride and 11 parts of anhydrous sodium carbonate in 500 parts of toluene. Add a toluene solution containing 14.2 parts of octadecylamine at -5℃. After reacting for 4 hours, filter and concentrate under reduced pressure. After drying, dissolve in 500 parts of acetone solution. Add an acetone solution containing 1.2 parts of hexamethylenediamine at 35℃. Adjust the pH to 7. After reacting for 4 hours, filter, wash the filter cake, and dry to obtain product A. s2: 2.6 parts of diethanolamine and 1.6 parts of boric acid were placed in 50 parts of toluene. Under a nitrogen atmosphere, the mixture was heated to 120°C and refluxed to remove water for 2 hours. After cooling, 7.2 parts of phenol were added and refluxed to remove water for 8 hours. After cooling, the toluene was removed by vacuum distillation and purified to obtain product B. s3: 12 parts of product A, 2 parts of product B, and 2 parts of anhydrous sodium carbonate were placed in 150 parts of anhydrous N,N-dimethylformamide. The mixture was heated to 130℃ and reacted for 10 h. The mixture was then filtered, the filter cake was washed, and the functionalized borate ester coupling agent was obtained.

[0022] Performance testing: 1. Take the outer sheath of the submarine cables made in Examples 1-3 and Comparative Examples 1-3, and conduct tensile tests using a universal testing machine according to GB / T1040.2-2022. The size of the test sample is 75×10×3mm, and the tensile speed is 15mm / min. 2. Immerse the test sample in artificial seawater with a salt concentration of 15% and a temperature of 50℃. After 2000 hours, take it out and test its tensile strength, and record the tensile strength retention rate. 3. Select 800W / m 3 The test sample was irradiated with an LED-UV 360nm ultraviolet lamp with sufficient oxygen for 1200 hours. After that, the sample was taken out and its tensile strength was tested. The tensile strength retention rate was recorded. Table 1

[0023] Conclusion: As can be seen from the above test data, the formulation design and process parameter adjustment of Example 3 achieved good performance. Based on Example 3, three comparative examples were made. In Comparative Example 1, the functionalized borate ester coupling agent was replaced with the commercially available silane coupling agent KH550, resulting in weaker bonding between the calcium carbonate-coated microfibers and the substrate, a significant decrease in tensile strength, and a significant decrease in performance after aging. In Comparative Example 2, the modified microfibers were replaced with modified calcium carbonate, lacking the technical point of fiber reinforcement, and the performance decreased more significantly than that of Comparative Example 1. However, due to the modification of the functionalized borate ester coupling agent, the aging performance was slightly better than that of Comparative Example 1. In Comparative Example 3, octadecylamine was replaced with octylamine in the preparation of the functionalized borate ester coupling agent, which weakened the entanglement between the agent and the substrate, resulting in a decrease in performance.

[0024] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a corrosion-resistant double-armored submarine cable, characterized in that, The preparation steps include the following: S1: Twisting and pressing copper wires together to form a copper conductor; S2: Extruding insulating material onto the surface of a copper conductor to form an insulating layer; S3: Extrude the insulating liner onto the surface of the insulating layer, and fill the space between the insulating liner and the insulating layer with foamed material to form a filler layer; S4: After covering the insulating inner liner with a double armor layer, a water-blocking layer is formed by overlapping and wrapping a semi-conductive non-woven fabric tape around the surface of the double armor layer. S5: Extruding corrosion-resistant submarine cable material onto the surface of the water-blocking layer to form an outer sheath layer, resulting in a corrosion-resistant double-armored submarine cable. The corrosion-resistant submarine cable material comprises the following raw material components: by weight, 75-90 parts high-density polyethylene, 30-50 parts ultra-high molecular weight polyethylene, 10-25 parts modified microfiber, 8-15 parts ethylene-vinyl acetate copolymer, 0.2-0.5 parts antioxidant, and 1-1.2 parts lubricant.

2. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 1, characterized in that, The preparation steps of the corrosion-resistant submarine cable material are as follows: after weighing the raw materials according to the mass proportions, high-density polyethylene, ultra-high molecular weight polyethylene, ethylene-vinyl acetate copolymer, modified microfiber, antioxidant and lubricant are placed in a mixer and mixed at 140-160℃ and 30-50 r / min. After mixing for 10-15 min, the mixture is fed into a twin-screw extruder and extruded and granulated to obtain the corrosion-resistant submarine cable material.

3. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 1, characterized in that, The preparation steps of the modified microfiber are as follows: polyethylene terephthalate, high-density polyethylene, and maleic anhydride-grafted ethylene-octene copolymer are dried and then mixed and extruded to obtain coarse particles; the coarse particles are crushed and drawn into fibers using a granulator, then dried by traction after a cold water bath, and sheared to obtain microfibers; the microfibers are ultrasonically treated in anhydrous ethanol for 40-60 min and then dried, then immersed in a dopamine hydrochloride solution, the pH of the solution is adjusted to 8.5 using Tris buffer, stirred for 24 h, washed and dried to obtain polydopamine-microfibers; the polydopamine-microfibers are immersed in a calcium chloride solution for gas mineralization to obtain calcium carbonate-coated microfibers; the calcium carbonate-coated microfibers are mixed with a functionalized borate ester coupling agent and reacted at 100-120℃ for 20-30 min to obtain modified microfibers.

4. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 3, characterized in that, The coarse particles comprise the following raw material components: by weight, 10-20 parts polyethylene terephthalate, 75-85 parts high-density polyethylene, and 5-10 parts maleic anhydride-grafted ethylene-octene copolymer; the process parameters for the mixed extrusion are: extrusion zone temperature of 195-205℃, 220-230℃, 245-255℃, 260-270℃, and 245-255℃, and rotation speed of 100 rpm; the average diameter of the microfibers is 1-3 μm, and the length is 3-5 mm.

5. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 3, characterized in that, The amount of the functionalized borate coupling agent is 1-3 wt% of the calcium carbonate-coated microfibers.

6. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 3, characterized in that, The preparation steps of the functionalized borate ester coupling agent are as follows: s1: Dissolve cyanuric chloride and anhydrous sodium carbonate in toluene, add a toluene solution containing long-chain amines at -5~0℃, react for 3-4 hours, filter under reduced pressure and concentrate, dry and dissolve in acetone solution, add acetone solution containing short-chain amines at 30-35℃, adjust pH to 6-7, react for 2-4 hours, filter, wash filter cake and dry to obtain product A; s2: Diethanolamine and boric acid were placed in toluene, heated to 115-120℃ under nitrogen atmosphere, refluxed for 2 hours to remove water, cooled, phenol was added, refluxed for 8 hours to remove water, cooled, and then purified by vacuum distillation to remove toluene to obtain product B. s3: Product A and product B, along with anhydrous sodium carbonate, were placed in anhydrous N,N-dimethylformamide and heated to 130℃ for 8-10 hours. The mixture was then filtered, the filter cake was washed, and the functionalized borate ester coupling agent was obtained.

7. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 6, characterized in that, The long-chain amine in s1 is any one of dodecylamine, hexadecylamine, and octadecylamine; the short-chain amine is any one of ethylenediamine, butanediamine, and hexamethylenediamine; product A includes the following raw material components: 15-20 parts cyanuric chloride, 16.5-22 parts long-chain amine, and 2.2-3 parts short-chain amine; the mass ratio of product A to product B in s3 is (5-7):

1.

8. The method for preparing a corrosion-resistant double-armored submarine cable according to claim 1, characterized in that, The water-blocking buffer layer is formed by wrapping semi-conductive non-woven fabric tape with an overlap rate of 20-25%; the filler is an ethylene-vinyl acetate copolymer foam filler with a density of 80-90 kg / m³. 3 The double armor layer is obtained by twisting galvanized steel wire in two reverse directions.

9. A corrosion-resistant double-armored submarine cable, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

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