Waterproof pressure-resistant insulated reliable submarine cable and preparation method thereof

Abstract

This invention discloses a waterproof, pressure-resistant, and reliably insulated submarine cable and its preparation method, relating to the field of cable technology. The preparation method specifically includes the following steps: S1: Extruding pressure-resistant insulating material onto a conductive core and heat-treating it to form a pressure-resistant insulating layer; S2: Wrapping an aluminum-plastic composite tape around the pressure-resistant insulating layer to form a shielding layer; S3: Winding a steel tape onto the shielding layer to form an armor layer; S4: Extruding a waterproof reinforcing material onto the armor layer and heat-treating it to form a waterproof reinforcing layer, thus obtaining a waterproof, pressure-resistant, and reliably insulated submarine cable. The submarine cable prepared by this invention possesses excellent waterproof and pressure-resistant insulation properties through the pressure-resistant insulating layer and the waterproof reinforcing layer. It also exhibits excellent mechanical and thermal aging resistance properties, enabling it to adapt to harsh underwater working environments and greatly ensuring the stable and reliable operation of the submarine cable, which is of great significance.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a waterproof, pressure-resistant, and reliably insulated submarine cable and its manufacturing method. Background Technology

[0002] Submarine cables are core equipment for offshore wind power, island power grid interconnection, and transoceanic power transmission. They operate in complex deep-sea environments, enduring high pressure, high salinity, and high corrosion. Their waterproofing, pressure resistance, and insulation performance directly determine the safety and stability of power transmission. Currently, the insulation layers of submarine cables often use single-filler modified polyethylene. However, the filler has poor compatibility with the matrix, easily forming micropores at the interface, resulting in poor high-voltage breakdown resistance; furthermore, their resistance to thermal aging is insufficient; and their surface waterproofing performance needs further improvement.

[0003] In summary, to solve the above problems, this invention provides a waterproof, pressure-resistant, and reliably insulated submarine cable, which is of great significance for improving the reliability and stability of submarine cables. Summary of the Invention

[0004] The purpose of this invention is to provide a waterproof, pressure-resistant, and reliably insulated submarine cable and its manufacturing method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for manufacturing a waterproof, pressure-resistant, and reliably insulated submarine cable includes the following steps:

[0007] S1: Extruding the pressure-resistant insulating material onto the conductive core and heat-treating it to form a pressure-resistant insulating layer;

[0008] S2: Wrap the aluminum-plastic composite tape around the pressure-resistant insulation layer to form a shielding layer;

[0009] S3: Wind the steel strip onto the shielding layer to form an armor layer;

[0010] S4: Extrude the waterproof reinforcing material onto the armor layer, heat treat it to form a waterproof reinforcing layer, and obtain a waterproof, pressure-resistant, and reliably insulated submarine cable.

[0011] Furthermore, the pressure-resistant insulating material comprises the following raw material components in parts by weight: 100 parts of low-density polyethylene, 7-13 parts of modified filler A, 3-5 parts of maleic anhydride-grafted polyethylene, 2-3 parts of crosslinking agent, 0.5-1.5 parts of lubricant, and 0.2-0.3 parts of antioxidant.

[0012] Furthermore, the waterproof reinforcing material comprises the following raw material components in parts by weight: 100 parts of low-density polyethylene, 7-13 parts of modified filler B, 3-5 parts of maleic anhydride-grafted polyethylene, 2-3 parts of crosslinking agent, 0.5-1.5 parts of lubricant, and 0.2-0.3 parts of antioxidant.

[0013] Furthermore, the crosslinking agent is obtained by mixing and compounding a peroxide crosslinking agent and an allyl co-crosslinking agent in a mass ratio of 1:(0.5~1).

[0014] Further, the peroxide crosslinking agent is any one of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and α,α-bis(tert-butylperoxy)diisopropylbenzene.

[0015] Furthermore, the alkenyl co-crosslinking agent includes one or a combination of several of triallyl cyanurate, triallyl isocyanurate, and trimethylolpropane trimethacrylate.

[0016] Furthermore, the lubricant includes, but is not limited to, one or more combinations of magnesium stearate, calcium stearate, zinc stearate, polyethylene wax, and ethylene bis-stearamide.

[0017] Further, the preparation method of the modified filler A is as follows: (1) Add filler A to a stirring pot, stir and heat to 50-60℃ at a speed of 50-80r / min, then spray silane hydrolysate into it with a spray particle size of 50-100μm and a spray rate of 5-10mL / min, keep warm and stir for 1-3h, discharge the material, and vacuum dry to obtain silane modified filler A; (2) Under nitrogen protection, add 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and allyl alcohol glycidyl ether to dimethylformamide, stir and mix for 10-20min, then add ferric chloride, stir and react at 70-80℃ for 2-4h, and obtain antioxidant by vacuum distillation, washing and vacuum drying; (3) Under nitrogen protection, add antioxidant Add tert-butyldimethylchlorosilane to dimethylformamide, stir and mix for 10-20 min, then add triethylamine, stir and react at 0-20℃ for 1-2 h, and obtain TBS protective antioxidant by vacuum distillation, washing and vacuum drying; (4) Under nitrogen protection, add silane modified filler A and TBS protective antioxidant to dimethylformamide, stir and mix for 10-20 min, then add benzoyl peroxide, stir and react at 90-100℃ for 6-18 h; then add maleic anhydride grafted polyethylene, heat to 100-110℃, and continue stirring and reacting for 12-24 h; after cooling to room temperature, add tetrabutylammonium fluoride, stir and react for 1-2 h, and obtain modified filler A by filtration, washing and vacuum drying.

[0018] Furthermore, the filler A is obtained by mixing and compounding aluminum fluoride, aluminum oxide, and needle-shaped aluminum oxide in a mass ratio of (1~2):(6~8):(1~2).

[0019] Furthermore, the ratio of the filler A to the silane hydrolysate is 1g:(0.1~0.3)mL.

[0020] Furthermore, the fluorinated aluminum nitride is prepared according to the modification method disclosed in the prior art CN109535649A "A method and system for modifying aluminum nitride filler in electrical epoxy resin".

[0021] Furthermore, the antioxidant comprises the following raw material components in parts by weight: 2.5-3 parts of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 1-1.2 parts of allyl alcohol glycidyl ether, 0.02-0.04 parts of ferric chloride, and 10-20 parts of dimethylformamide.

[0022] Furthermore, the TBS protective antioxidant comprises the following raw material components in parts by weight: 3-3.5 parts antioxidant, 3.5-4 parts tert-butyldimethylchlorosilane, 6-10 parts triethylamine, and 30-40 parts dimethylformamide.

[0023] Further, the modified filler A comprises the following raw material components in parts by weight: 13-17 parts of silane modified filler A, 2-2.6 parts of antioxidant, 1-2 parts of maleic anhydride grafted polyethylene, 0.01-0.02 parts of benzoyl peroxide, 0.8-1.2 parts of tetrabutylammonium fluoride, and 40-50 parts of dimethylformamide.

[0024] Further, the preparation method of the modified filler B is as follows: (1) Add filler B to a mixing pot, stir and heat to 50-60℃ at a speed of 50-80r / min, then spray silane hydrolysate into it with a spray particle size of 50-100μm and a spray rate of 5-10mL / min, keep warm and stir for 1-3h, discharge the material, vacuum dry to obtain silane modified filler B; (2) Under nitrogen protection, add perfluorocyclohexane carboxylic acid and allyl alcohol glycidyl ether to dimethylformamide, stir and mix for 10-20min, then... Add ferric chloride to it and stir at 70~80℃ for 2~4h. After vacuum distillation, washing and vacuum drying, the waterproofing agent is obtained. (3) Under nitrogen protection, silane modified filler B and waterproofing agent are added to dimethylformamide and stirred for 10~20min. Then benzoyl peroxide is added to it and stirred at 90~100℃ for 6~18h. Then maleic anhydride grafted polyethylene is added to it, the temperature is raised to 100~110℃, and the stirring reaction continues for 12~24h. After filtration, washing and vacuum drying, modified filler B is obtained.

[0025] Furthermore, the filler B is obtained by mixing and compounding talc powder and polytetrafluoroethylene fiber in a mass ratio of (8~9):(1~2).

[0026] Furthermore, the ratio of the filler B to the silane hydrolysate is 1g:(0.1~0.3)mL.

[0027] Furthermore, the waterproofing agent comprises the following raw material components in parts by weight: 3-3.5 parts perfluorocyclohexane carboxylic acid, 1-1.2 parts allyl alcohol glycidyl ether, 0.02-0.04 parts ferric chloride, and 10-20 parts dimethylformamide.

[0028] Further, the modified filler B comprises the following raw material components in parts by weight: 13-17 parts of silane modified filler B, 2-2.6 parts of waterproofing agent, 1-2 parts of maleic anhydride grafted polyethylene, 0.01-0.02 parts of benzoyl peroxide, and 40-50 parts of dimethylformamide.

[0029] Furthermore, the preparation method of the silane hydrolysate is as follows: add aminosilane coupling agent and vinylsilane coupling agent to 90~95wt% ethanol aqueous solution, add acetic acid to adjust the pH to 4.5~5, and stir and mix at 50~60℃ for 1~1.5h to obtain silane hydrolysate.

[0030] Furthermore, the volume ratio of the aminosilane coupling agent, the vinylsilane coupling agent, and the ethanol aqueous solution is (0.8~1):(0.8~1):8.

[0031] Furthermore, in this invention, the maleic anhydride grafting rate of the maleic anhydride-grafted polyethylene is 0.8~1.5wt%.

[0032] Furthermore, the preparation method of the pressure-resistant insulating material or waterproof reinforcing material is as follows: the raw material components are mixed evenly according to the formula ratio, and then melt-extruded to obtain the pressure-resistant insulating material or waterproof reinforcing material.

[0033] Furthermore, the melt extrusion is carried out using a single-screw extruder with the following operating parameters: melt extrusion temperature of 162~170℃, screw length-to-diameter ratio of 25~30:1, and compression ratio of 2.5~3:1.

[0034] Furthermore, the extrusion parameters are: extrusion temperature of 158~162℃ and screw speed of 30~50r / min.

[0035] Furthermore, the heat treatment is carried out using saturated steam, and the parameters of the heat treatment are: heat treatment temperature of 170~180℃ and heat treatment time of 30~40min.

[0036] Furthermore, the steel strip has a thickness of 0.15~0.23mm, a width of 8~20mm, and a winding spacing of 2~4 times the width of the steel strip.

[0037] Furthermore, the diameter of the conductive core is 10-14 mm; the thickness of the voltage-resistant insulating layer is 8-10 mm; the thickness of the shielding layer is 0.5-1 mm; and the thickness of the waterproof reinforcement layer is 10-12 mm.

[0038] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0039] (1) In this invention, aluminum nitride, alumina, and needle-shaped alumina are used as filler A. The three work together to give polyethylene excellent insulation and breakdown resistance, thereby ensuring the voltage resistance insulation performance of the voltage-resistant insulation layer. In addition, aluminum nitride and alumina, as particulate reinforcing fillers, fill the pores in polyethylene, playing a role in toughening, creep resistance, and improving heat resistance; while needle-shaped alumina can be used as fiber reinforcing filler to form a fiber reinforcing network in polyethylene, greatly improving the tensile strength, flexural strength, etc. of polyethylene; under the synergistic effect of the three, the stability of the voltage-resistant insulation layer is further guaranteed. Considering the poor compatibility of the three components in the resin, a silane coupling agent was designed to treat the surface of filler A. To further enhance the performance of filler A, in addition to using a conventional vinyl silane coupling agent, an amino silane coupling agent was added to simultaneously introduce vinyl and amino groups onto the surface of filler A, resulting in silane-modified filler A. Next, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and allyl alcohol glycidyl ether were reacted to prepare an antioxidant containing hindered phenolic groups. Finally, an antioxidant and maleic anhydride-grafted polyethylene were designed to graft and modify the silane-modified filler A, resulting in modified filler A. However, the antioxidant contains hindered phenolic groups. If it reacts directly with silane-modified filler A, the hindered phenolic groups will consume the free radicals generated by benzoyl peroxide, thus preventing the subsequent grafting modification process of silane-modified filler A from proceeding effectively. Therefore, the proposed solution uses tert-butyldimethylchlorosilane to shield the phenolic hydroxyl groups on the antioxidant, ensuring the subsequent grafting modification reaction process. Finally, tetrabutylammonium fluoride is added to remove the TBS protecting group, thus preparing modified filler A. By modifying filler A through grafting with antioxidant and maleic anhydride onto polyethylene, the compatibility and dispersibility of filler A in polyethylene are enhanced, while the thermo-oxidative resistance of the withstand voltage insulation layer is further improved. Moreover, the hindered phenolic groups do not migrate and precipitate like the added antioxidants, which can greatly ensure the long-term stability of the withstand voltage insulation layer. The inventors also considered the issue of aluminum nitride's susceptibility to hydrolysis. Since water is inevitably encountered during the modification process using silane coupling agents, the invention incorporates fluorination treatment of the aluminum nitride to enhance its hydrolysis resistance and prevent a decrease in modification effectiveness due to hydrolysis. Furthermore, the silane hydrolysate is prepared using a 90-95 wt% high-ethanol aqueous solution and introduced via a stirring spray. Therefore, this invention, through a triple hydrolysis-resistant system of "fluorination treatment + high-ethanol aqueous solution + gentle stirring," fundamentally solves the problem of voltage withstand insulation layer performance degradation caused by aluminum nitride hydrolysis. It is important to note that the stirring speed in the mixing tank should not be too fast to avoid damaging the needle-like alumina; a speed of 50-80 r / min is recommended.

[0040] (2) In this invention, talc powder and polytetrafluoroethylene fiber are selected as filler B. Both have excellent waterproof performance and can improve the waterproof performance of the waterproof reinforcement layer. Similarly, the combination of particles and fibers can also improve the relevant mechanical properties of the waterproof reinforcement layer and ensure its long-term stability. In this invention, aminosilane coupling agent and vinylsilane coupling agent are used to modify it. Amino and vinyl groups are introduced into filler B to obtain silane-modified filler B. Then, perfluorocyclohexane carboxylic acid and allyl alcohol glycidyl ether are reacted to prepare a fluorine-containing waterproofing agent. Then, the waterproofing agent and maleic anhydride grafted polyethylene are used to graft and modify the silane-modified filler B. While enhancing the compatibility and dispersion of filler B in polyethylene, the waterproof performance of the waterproof reinforcement layer is further enhanced. At the same time, the corrosion resistance of polyethylene is also enhanced, thus achieving stable protection of the overall performance of the submarine cable.

[0041] (3) In this invention, maleic anhydride-grafted polyethylene is added to the pressure-resistant insulation material and the waterproof reinforcement layer material as a reinforcing resin. It can further eliminate the interfacial pores between the filler and the polyethylene matrix. At the same time, maleic anhydride can be used as a crosslinking active group to further improve the crosslinking uniformity of the pressure-resistant insulation layer and the waterproof reinforcement layer, thereby improving the pressure-resistant insulation performance, waterproof performance and corrosion resistance of the submarine cable.

[0042] In summary, this invention obtains modified filler A and modified filler B by selecting and modifying fillers; and uses them to specifically enhance the functional layers of submarine cables, resulting in a pressure-resistant insulation layer and a waterproof reinforcement layer. These two specific functional layers endow submarine cables with excellent waterproof, pressure-resistant, and insulation properties, while also possessing excellent mechanical and thermal aging resistance properties, enabling them to adapt to harsh underwater working environments and greatly ensuring the stable and reliable operation of submarine cables, which is of great significance. Detailed Implementation

[0043] 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.

[0044] 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:

[0045] In the following examples, the low-density polyethylene is LLDPE and the brand is Saudi SABIC.

[0046] 2,5-Dimethyl-2,5-di(tert-butylperoxide)hexane, CAS No. 78-63-7; triallyl cyanurate, CAS No. 101-37-1; both purchased from Taizhou Suze Chemical Materials Co., Ltd.

[0047] Maleic anhydride-grafted polyethylene, model 900E, with a maleic anhydride grafting rate of 0.8~1.2wt% and a melt index of 1.0~3.0g / 10min, was purchased from Nanjing Feiteng New Material Technology Co., Ltd.

[0048] Aluminum nitride, particle size 0.5~1μm; alumina, particle size 1~3μm; talc, particle size 1~3μm; needle-shaped alumina, diameter 2~3μm, aspect ratio 8~10:1; polytetrafluoroethylene fiber, diameter 2~3μm, aspect ratio 8~10:1; antioxidant 1076; all purchased from Hubei Yongkuo Technology Co., Ltd.

[0049] 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, CAS No. 20170-32-5, was purchased from Shanghai Dingmiao Chemical Technology Co., Ltd.

[0050] Perfluorocyclohexanecarboxylic acid, CAS number 374-88-9, was purchased from Chengdu Sitiande Biotechnology Co., Ltd.

[0051] The aluminum-plastic composite tape, with an aluminum thickness of 0.15mm and a copolymer thickness of 0.05mm, was purchased from Suzhou Zhihong Cable Materials Co., Ltd.

[0052] Galvanized steel strip, with specifications of 0.2mm (thickness) × 10mm (width), purchased from Zibo Chijiang Trading Co., Ltd.

[0053] Fluorinated aluminum nitride was prepared according to the modification method disclosed in the existing technology CN109535649A "A method and system for modifying aluminum nitride filler in electrical epoxy resin"; the specific method is as follows: aluminum nitride is placed in a quartz plasma reactor for plasma fluorination modification. The modification parameters are: Ar flow rate of 2.5 SLM, CF4 flow rate of 0.25 SLM, voltage amplitude of 10kV, voltage frequency of 50kHz, and modification treatment for 45min.

[0054] Preliminary preparations:

[0055] 1. Preparation of crosslinking agent: 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane and triallyl cyanurate are mixed and compounded at a mass ratio of 1:0.75 to obtain the crosslinking agent;

[0056] 2. Preparation of silane hydrolysate: γ-aminopropyltriethoxysilane and vinyltriethoxysilane were added to a 92wt% aqueous ethanol solution, and acetic acid was added to adjust the pH to 4.8. The mixture was stirred and mixed at 55℃ for 1 h to obtain the silane hydrolysate; the volume ratio of γ-aminopropyltriethoxysilane, vinyltriethoxysilane, and aqueous ethanol solution was 1:1:8.

[0057] 3. Preparation of vinylsilane hydrolysate: Add vinyltriethoxysilane to a 92wt% aqueous ethanol solution, add acetic acid to adjust the pH to 4.8, and stir and mix at 55℃ for 1 h to obtain vinylsilane hydrolysate; the volume ratio of vinyltriethoxysilane to aqueous ethanol solution is 2:8.

[0058] Example 1: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0059] 1. Preparation of modified filler A: (1) Filler A (aluminum fluoride nitride, alumina, and needle alumina mixed in a mass ratio of 1.5:7:1.5) was added to a mixing pot and stirred at 60 r / min to raise the temperature to 55°C. Then, silane hydrolysate was sprayed into the pot at a spray particle size of 60 μm and a spray rate of 7.5 mL / min. The mixture was kept warm and stirred for 2 h. The mixture was then discharged and dried under vacuum to obtain silane modified filler A. The ratio of filler A to silane hydrolysate was 1 g: 0.2 mL. (2) Under nitrogen protection, 2.75 parts of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 1.1 parts of allyl alcohol glycidyl ether were added to 15 parts of dimethylformamide and stirred for 15 min. Then, 0.03 parts of ferric chloride were added and stirred at 75°C for 3 h. The mixture was then distilled under reduced pressure, washed, and dried under vacuum to obtain the final product. Antioxidant; (3) Under nitrogen protection, 3.25 parts of antioxidant and 3.75 parts of tert-butyldimethylchlorosilane were added to 35 parts of dimethylformamide and stirred for 15 min. Then 8 parts of triethylamine were added and stirred at 10°C for 1.5 h. After vacuum distillation, washing and vacuum drying, TBS protective antioxidant was obtained; (4) Under nitrogen protection, 15 parts of silane modified filler A and 2.3 parts of TBS protective antioxidant were added to 45 parts of dimethylformamide and stirred for 15 min. Then 0.015 parts of benzoyl peroxide were added and stirred at 95°C for 12 h. Then 1.5 parts of maleic anhydride grafted polyethylene were added, the temperature was raised to 105°C, and the stirring reaction was continued for 18 h. After cooling to room temperature, 1 part of tetrabutylammonium fluoride was added and stirred for 1.5 h. After filtration, washing and vacuum drying, modified filler A was obtained;

[0060] 2. Preparation of modified filler B: (1) Filler B (talc powder and polytetrafluoroethylene fiber mixed in a mass ratio of 8.5:1.5) was added to a mixing pot and stirred at a speed of 60 r / min to raise the temperature to 55°C. Then, silane hydrolysate was sprayed into it with a spray particle size of 60 μm and a spray rate of 7.5 mL / min. The mixture was kept warm and stirred for 2 h, discharged, and vacuum dried to obtain silane modified filler B. The ratio of filler B to silane hydrolysate was 1 g: 0.2 mL. (2) Under nitrogen protection, 3.25 parts of perfluorocyclohexane carboxylic acid and 1.1 parts of allyl alcohol glycidyl ether were added to 15 (2) In 35 parts of dimethylformamide, stir and mix for 15 min, then add 0.03 parts of ferric chloride, stir and react at 75°C for 3 h, and then obtain the waterproofing agent by vacuum distillation, washing and vacuum drying; (3) Under nitrogen protection, add 15 parts of silane modified filler B and 2.3 parts of waterproofing agent to 35 parts of dimethylformamide, stir and mix for 15 min, then add 0.015 parts of benzoyl peroxide, stir and react at 95°C for 12 h; then add 1.5 parts of maleic anhydride grafted polyethylene, heat to 105°C, continue stirring and reacting for 18 h, and then obtain the modified filler B by filtration, washing and vacuum drying;

[0061] 3.S1: Install a withstand voltage insulation layer:

[0062] S11: Mix 100 parts of low-density polyethylene, 10 parts of modified filler A, 4 parts of maleic anhydride grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude them at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material;

[0063] S12: Extrude the voltage-resistant insulating material onto a φ12mm pure copper conductive core. The extrusion parameters are: extrusion temperature of 160℃ and screw speed of 40r / min. Then, perform heat treatment with saturated steam. The heat treatment parameters are: heat treatment temperature of 175℃ and heat treatment time of 35min to form a 9mm thick voltage-resistant insulating layer.

[0064] S2: Set up a shielding layer: Wrap the aluminum-plastic composite tape around the pressure-resistant insulation layer to form a 0.75mm thick shielding layer;

[0065] S3: Set up the armor layer: wind the galvanized steel strip onto the shielding layer with a winding spacing of 3 times the width of the steel strip to form the armor layer;

[0066] S4: Install a waterproof reinforcement layer:

[0067] S41: Mix 100 parts of low-density polyethylene, 10 parts of modified filler B, 4 parts of maleic anhydride grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude them at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material;

[0068] S42: Extrude the waterproof reinforcement material onto the armor layer. The extrusion parameters are: extrusion temperature of 160℃ and screw speed of 40r / min. Then, perform heat treatment with saturated steam. The heat treatment parameters are: heat treatment temperature of 175℃ and heat treatment time of 35min to form an 11mm thick waterproof reinforcement layer, resulting in a waterproof, pressure-resistant, and reliable submarine cable.

[0069] Example 2: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0070] Example 2 is based on Example 1, but with the following adjustment: the amount of raw material components for the voltage-resistant insulating material is adjusted, while other processes remain unchanged. Specifically:

[0071] S11: Mix 100 parts of low-density polyethylene, 7 parts of modified filler A, 3 parts of maleic anhydride grafted polyethylene, 2 parts of crosslinking agent, 0.5 parts of calcium stearate, and 0.2 parts of antioxidant 1076 evenly, and melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material.

[0072] Example 3: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0073] Example 3 is based on Example 1, but with the following adjustment: the amount of raw material components in the voltage-resistant insulating material is adjusted, while other processes remain unchanged. Specifically:

[0074] S11: Mix 100 parts of low-density polyethylene, 13 parts of modified filler A, 5 parts of maleic anhydride grafted polyethylene, 3 parts of crosslinking agent, 1.5 parts of calcium stearate, and 0.3 parts of antioxidant 1076 evenly, and melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material.

[0075] Example 4: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0076] Example 4 is based on Example 1, but with the following adjustment: the amount of raw material components for the waterproofing reinforcement material is adjusted, while other processes remain unchanged. Specifically:

[0077] S41: Mix 100 parts of low-density polyethylene, 7 parts of modified filler B, 3 parts of maleic anhydride grafted polyethylene, 2 parts of crosslinking agent, 0.5 parts of calcium stearate, and 0.2 parts of antioxidant 1076 evenly, and then melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material.

[0078] Example 5: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0079] Example 5 is based on Example 1, but with the following adjustment: the amount of raw material components for the waterproofing reinforcement material is adjusted, while other processes remain unchanged. Specifically:

[0080] S41: Mix 100 parts of low-density polyethylene, 13 parts of modified filler B, 5 parts of maleic anhydride grafted polyethylene, 3 parts of crosslinking agent, 1.5 parts of calcium stearate, and 0.3 parts of antioxidant 1076 evenly, and then melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material.

[0081] The following is a control experiment based on Example 1, with comparative examples 1 to 7, as detailed below:

[0082] Comparative Example 1: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0083] Comparative Example 1 is based on Example 1, with the following adjustment: no further modification treatment is applied to the silane-modified filler A, while other processes remain unchanged. Specifically:

[0084] S11: Mix 100 parts of low-density polyethylene, 10 parts of silane-modified filler A, 4 parts of maleic anhydride-grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material.

[0085] Comparative Example 2: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0086] Comparative Example 2 is based on Example 1, with the following adjustment: no further modification treatment is applied to the silane-modified filler B, while other processes remain unchanged. Specifically:

[0087] S41: Mix 100 parts of low-density polyethylene, 10 parts of silane-modified filler B, 4 parts of maleic anhydride-grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and then melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material.

[0088] Comparative Example 3: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0089] Comparative Example 3 is based on Example 1, with the following adjustment: maleic anhydride-grafted polyethylene is not added to the pressure-resistant insulation material and the waterproof reinforcement layer, while other processes remain unchanged. Specifically:

[0090] S11: Mix 100 parts of low-density polyethylene, 10 parts of modified filler A, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude them at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material.

[0091] …

[0092] S41: Mix 100 parts of low-density polyethylene, 10 parts of modified filler B, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material.

[0093] Comparative Example 4: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0094] Comparative Example 4 is based on Example 1, with the following adjustment: vinyl silane hydrolysate was used to modify filler A and filler B, while other processes remained unchanged. Specifically:

[0095] 1. Preparation of modified filler A: (1) Filler A (aluminum fluoride nitride, alumina, and needle alumina mixed in a mass ratio of 1.5:7:1.5) was added to a mixing pot, stirred at 60 r / min and heated to 55 °C, and then vinyl silane hydrolysate was sprayed into it with a spray particle size of 60 μm and a spray rate of 7.5 mL / min. The mixture was kept warm and stirred for 2 h, discharged, and vacuum dried to obtain silane modified filler A. The ratio of filler A to vinyl silane hydrolysate was 1 g: 0.2 mL. (2) Under nitrogen protection, 2.75 parts of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 1.1 parts of Allyl alcohol glycidyl ether was added to 15 parts of dimethylformamide and stirred for 15 min. Then 0.03 parts of ferric chloride were added and stirred at 75°C for 3 h. After vacuum distillation, washing and vacuum drying, an antioxidant was obtained. (3) Under nitrogen protection, 15 parts of silane modified filler A and 2.3 parts of antioxidant were added to 35 parts of dimethylformamide and stirred for 15 min. Then 0.015 parts of benzoyl peroxide were added and stirred at 95°C for 12 h. Then 1.5 parts of maleic anhydride grafted polyethylene were added, the temperature was raised to 105°C, and the stirring reaction was continued for 18 h. After filtration, washing and vacuum drying, modified filler A was obtained.

[0096] 2. Preparation of modified filler B: (1) Filler B (talc powder and polytetrafluoroethylene fiber mixed in a mass ratio of 8.5:1.5) was added to a mixing pot and stirred at a speed of 60 r / min to raise the temperature to 55°C. Then, vinyl silane hydrolysate was sprayed into it with a spray particle size of 60 μm and a spray rate of 7.5 mL / min. The mixture was kept warm and stirred for 2 h, discharged, and vacuum dried to obtain silane modified filler B. The ratio of filler B to vinyl silane hydrolysate was 1 g: 0.2 mL. (2) Under nitrogen protection, 3.25 parts of perfluorocyclohexane carboxylic acid and 1.1 parts of allyl alcohol glycidyl ether were added to Add 15 parts of dimethylformamide, stir and mix for 15 min, then add 0.03 parts of ferric chloride, stir and react at 75°C for 3 h, and obtain waterproofing agent by vacuum distillation, washing and vacuum drying; (3) Under nitrogen protection, add 15 parts of silane modified filler B and 2.3 parts of waterproofing agent to 35 parts of dimethylformamide, stir and mix for 15 min, then add 0.015 parts of benzoyl peroxide, stir and react at 95°C for 12 h; then add 1.5 parts of maleic anhydride grafted polyethylene, heat to 105°C, continue stirring and reacting for 18 h, and obtain modified filler B by filtration, washing and vacuum drying.

[0097] Comparative Example 5: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0098] Comparative Example 5 is based on Example 1, with the following adjustments: no fillers are added to the pressure-resistant insulating material and the waterproof reinforcing material, while other processes remain unchanged. Specifically:

[0099] S11: Mix 100 parts of low-density polyethylene, 4 parts of maleic anhydride grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude them at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material.

[0100] …

[0101] S41: Mix 100 parts of low-density polyethylene, 4 parts of maleic anhydride-grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material.

[0102] Comparative Example 6: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0103] Comparative Example 6 is based on Example 1, with the following adjustments: Modified filler A is added to both the voltage-resistant insulating material and the waterproof reinforcing material, while other processes remain unchanged. Specifically:

[0104] S11: Mix 100 parts of low-density polyethylene, 10 parts of modified filler A, 4 parts of maleic anhydride grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude them at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a pressure-resistant insulating material;

[0105] …

[0106] S41: Mix 100 parts of low-density polyethylene, 10 parts of modified filler A, 4 parts of maleic anhydride grafted polyethylene, 2.5 parts of crosslinking agent, 1 part of calcium stearate, and 0.25 parts of antioxidant 1076 evenly, and melt-extrude the mixture at 165°C using a single-screw extruder with a screw length-to-diameter ratio of 30:1 and a compression ratio of 3:1 to obtain a waterproof reinforcing material.

[0107] Comparative Example 7: A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable:

[0108] Comparative Example 7 is based on Example 1, with the following adjustment: the antioxidant is not protected with TBS, while other processes remain unchanged. Specifically:

[0109] 1. Preparation of modified filler A: (1) Filler A (aluminum fluoride nitride, alumina, and needle alumina mixed in a mass ratio of 1.5:7:1.5) was added to a mixing pot and stirred at a speed of 60 r / min to raise the temperature to 55°C. Then, silane hydrolysate was sprayed into it with a spray particle size of 60 μm and a spray rate of 7.5 mL / min. The mixture was kept warm and stirred for 2 h, discharged, and vacuum dried to obtain silane modified filler A. The ratio of filler A to silane hydrolysate was 1 g: 0.2 mL. (2) Under nitrogen protection, 2.75 parts of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 1.1 parts of allyl alcohol were added. Glycidyl ether was added to 15 parts of dimethylformamide and stirred for 15 min. Then 0.03 parts of ferric chloride were added and stirred at 75°C for 3 h. After vacuum distillation, washing and vacuum drying, an antioxidant was obtained. (3) Under nitrogen protection, 15 parts of silane-modified filler A and 2.3 parts of antioxidant were added to 45 parts of dimethylformamide and stirred for 15 min. Then 0.015 parts of benzoyl peroxide were added and stirred at 95°C for 12 h. Then 1.5 parts of maleic anhydride-grafted polyethylene were added, the temperature was raised to 105°C, and the stirring reaction was continued for 18 h. After filtration, washing and vacuum drying, modified filler A was obtained.

[0110] Performance Testing: 1. At 160℃, the voltage-resistant insulating materials prepared in Examples 1-5 and Comparative Examples 1-7 were extruded into samples of 150mm × 50mm × 9mm (thickness) and heat-treated with saturated steam. The heat treatment parameters were: heat treatment temperature 175℃ and heat treatment time 35min, to obtain voltage-resistant insulation test samples to simulate voltage-resistant insulation layers. Under the same conditions, the waterproof reinforcing materials prepared in Examples 1-5 and Comparative Examples 1-7 were extruded into samples of 150mm × 50mm × 11mm (thickness) and heat-treated with saturated steam. The heat treatment parameters were: heat treatment temperature 175℃ and heat treatment time 35min, to obtain waterproof reinforcing test samples to simulate waterproof reinforcing layers. 2. The voltage-resistant insulating test samples were tested for high-voltage withstand performance and heat aging resistance. The waterproof reinforcing test samples were tested for water absorption resistance and corrosion resistance. The specific test methods are as follows:

[0111] (1) High voltage withstand performance test: The power frequency AC test method is used to apply a 35kV voltage at a frequency of 50Hz to the withstand voltage insulation test sample and maintain it for 10h;

[0112] (2) Heat aging resistance test: The withstand voltage insulation test sample was placed in an environment of 135℃ for 7 days, and then the tensile strength test was carried out. The test speed was 2mm / min. The tensile strength before and after heat aging was counted and the tensile strength change rate was calculated.

[0113] (3) Water absorption resistance test: Place the water-resistant enhanced test sample in a vacuum drying oven at 70℃ for 24h, cool it to room temperature in a desiccator, weigh and record the weight; then immerse the water-resistant enhanced test sample in deionized water at 70℃ for 96h, take it out, wipe the surface dry, weigh and record the weight; count the mass before and after water absorption, and calculate the water absorption rate;

[0114] (4) Corrosion resistance test: The water-resistant enhanced test sample was placed in a vacuum drying oven at 70℃ for 24h, cooled to room temperature in a desiccator, and weighed and recorded; the water-resistant enhanced test sample was immersed in a 3.5wt% NaCl solution at 70℃ for 96h, taken out, wiped dry, placed in a vacuum drying oven for 24h, cooled to room temperature in a desiccator, and weighed and recorded; the mass before and after corrosion was counted and the weight loss rate was calculated.

[0115] The specific test results are shown in Table 1 below:

[0116] Table 1

[0117] Test Project High pressure withstand performance Heat aging resistance Water absorption resistance Corrosion resistance Test Results Whether it is penetrated Tensile strength change rate (%) Water absorption rate (%) Weight loss rate (%) Example 1 no -8.27 0.07 0.02 Example 2 no -9.95 0.07 0.02 Example 3 no -7.92 0.07 0.02 Example 4 no -8.26 0.10 0.05 Example 5 no -8.27 0.06 0.02 Comparative Example 1 yes -16.33 0.07 0.02 Comparative Example 2 no -8.27 0.23 0.10 Comparative Example 3 yes -12.65 0.11 0.05 Comparative Example 4 no -10.34 0.10 0.04 Comparative Example 5 yes -34.11 0.42 0.31 Comparative Example 6 no -8.25 0.15 0.07 Comparative Example 7 yes -12.12 0.07 0.02

[0118] Results Analysis: As shown in Table 1 above, this invention obtains modified filler A and modified filler B by selecting and modifying fillers; and uses them to perform specific functional enhancement modifications on the functional layers of submarine cables, resulting in a pressure-resistant insulation layer and a waterproof reinforcement layer; through these two specific functional layers, the submarine cable is endowed with excellent waterproof, pressure-resistant and insulation properties, while also possessing excellent mechanical and thermal aging resistance properties, enabling it to adapt to the harsh underwater working environment, greatly ensuring the stable and reliable operation of the submarine cable, which is of great significance.

[0119] 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 of manufacturing a waterproof, pressure-resistant, insulated, and reliable submarine cable, characterized by: Includes the following steps: S1: Extruding the pressure-resistant insulating material onto the conductive core and heat-treating it to form a pressure-resistant insulating layer; S2: Wrap the aluminum-plastic composite tape around the pressure-resistant insulation layer to form a shielding layer; S3: Wind the steel strip onto the shielding layer to form an armor layer; S4: Extrude waterproof reinforcing material onto the armor layer, heat treat it to form a waterproof reinforcing layer, and obtain a waterproof, pressure-resistant, and reliably insulated submarine cable; The pressure-resistant insulating material comprises the following raw material components in parts by weight: 100 parts low-density polyethylene, 7-13 parts modified filler A, 3-5 parts maleic anhydride grafted polyethylene, 2-3 parts crosslinking agent, 0.5-1.5 parts lubricant, and 0.2-0.3 parts antioxidant; The modified filler A is obtained by sequentially modifying and grafting filler A with silane hydrolysate, antioxidant, and maleic anhydride grafted polyethylene; the filler A is obtained by mixing and compounding aluminum fluoride nitride, alumina, and needle alumina in a mass ratio of (1~2):(6~8):(1~2); The specific preparation method of the modified filler A is as follows: (1) Add the filler A to the silane hydrolysate in the form of spray while stirring, keep it at 50~60℃ and stir, then discharge and dry to obtain silane modified filler A; (2) Under nitrogen protection, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, allyl alcohol glycidyl ether and ferric chloride were added to dimethylformamide and stirred at 70~80℃. The mixture was then separated and purified to obtain an antioxidant. (3) Under nitrogen protection, antioxidant, tert-butyldimethylchlorosilane and triethylamine were added to dimethylformamide and stirred at 0~20℃. After separation and purification, TBS protective antioxidant was obtained. (4) Under nitrogen protection, silane modified filler A, TBS protective antioxidant and benzoyl peroxide were added to dimethylformamide and stirred at 90~100℃; then maleic anhydride grafted polyethylene was added and stirred at 100~110℃; finally tetrabutylammonium fluoride was added and stirred at room temperature. After separation and purification, modified filler A was obtained. The ratio of filler A to silane hydrolysate is 1 g: (0.1~0.3) mL; the antioxidant comprises the following raw material components in parts by weight: 2.5~3 parts of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 1~1.2 parts of allyl alcohol glycidyl ether, 0.02~0.04 parts of ferric chloride, and 10~20 parts of dimethylformamide; the TBS protective antioxidant comprises the following raw material components in parts by weight: 3~3.5 parts of antioxidant, 3.5~4 parts of tert-butyldimethylchlorosilane, 6~10 parts of triethylamine, and 30~40 parts of dimethylformamide; the modified filler A comprises the following raw material components in parts by weight: silane modified filler A 13-17 parts, antioxidant 2-2.6 parts, maleic anhydride grafted polyethylene 1-2 parts, benzoyl peroxide 0.01-0.02 parts, tetrabutylammonium fluoride 0.8-1.2 parts, dimethylformamide 40-50 parts.

2. The method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable according to claim 1, characterized in that: The waterproof reinforcement material comprises the following raw material components in parts by weight: 100 parts low-density polyethylene, 7-13 parts modified filler B, 3-5 parts maleic anhydride grafted polyethylene, 2-3 parts crosslinking agent, 0.5-1.5 parts lubricant, and 0.2-0.3 parts antioxidant. The modified filler B is obtained by sequentially modifying and grafting filler B with silane hydrolysate, waterproofing agent, and maleic anhydride grafted polyethylene; the filler B is obtained by mixing and compounding talc powder and polytetrafluoroethylene fiber in a mass ratio of (8~9):(1~2).

3. The method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable according to claim 2, characterized in that: The specific preparation method of the modified filler B is as follows: (1) Add the filler B to the silane hydrolysate in the form of spray while stirring, keep it at 50~60℃ and stir, then discharge and dry to obtain silane modified filler B; (2) Under nitrogen protection, perfluorocyclohexane carboxylic acid, allyl alcohol glycidyl ether and ferric chloride were added to dimethylformamide and stirred at 70~80℃. After separation and purification, a waterproofing agent was obtained. (3) Under nitrogen protection, silane-modified filler B, waterproofing agent, and benzoyl peroxide were added to dimethylformamide and stirred at 90~100℃. Then maleic anhydride-grafted polyethylene was added and stirred at 100~110℃. After separation and purification, modified filler B was obtained.

4. The method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable according to claim 3, characterized in that: The ratio of filler B to silane hydrolysate is 1g:(0.1~0.3)mL; the waterproofing agent comprises the following raw material components in parts by weight: perfluorocyclohexane carboxylic acid 3~3.5 parts, allyl alcohol glycidyl ether 1~1.2 parts, ferric chloride 0.02~0.04 parts, dimethylformamide 10~20 parts; the modified filler B comprises the following raw material components in parts by weight: silane modified filler B 13~17 parts, waterproofing agent 2~2.6 parts, maleic anhydride grafted polyethylene 1~2 parts, benzoyl peroxide 0.01~0.02 parts, dimethylformamide 40~50 parts.

5. A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable according to any one of claims 1 or 2, characterized in that: The preparation method of the silane hydrolysate is as follows: add aminosilane coupling agent and vinylsilane coupling agent to 90-95 wt% ethanol aqueous solution, add acetic acid to adjust the pH to 4.5-5, stir and mix at 50-60℃ to obtain silane hydrolysate; The volume ratio of the aminosilane coupling agent, the vinylsilane coupling agent, and the ethanol aqueous solution is (0.8~1):(0.8~1):

8.

6. A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable according to any one of claims 1 or 2, characterized in that: The maleic anhydride grafting rate of the maleic anhydride-grafted polyethylene is 0.8~1.5wt%.

7. A method for preparing a waterproof, pressure-resistant, and reliably insulated submarine cable according to any one of claims 1 or 2, characterized in that: The pressure-resistant insulating material or waterproof reinforcing material is obtained by melt extrusion. The working parameters of the melt extrusion are: melt extrusion temperature of 162~170℃, screw length-to-diameter ratio of 25~30:1, and compression ratio of 2.5~3:

1. The parameters of the extrusion are: extrusion temperature of 158~162℃ and screw speed of 30~50 r / min. The heat treatment is carried out using saturated steam, and the parameters of the heat treatment are: heat treatment temperature of 170~180℃ and heat treatment time of 30~40 min.

8. The waterproof, pressure-resistant, and reliably insulated submarine cable prepared by the method described in claim 1 yields a waterproof, pressure-resistant, and reliably insulated submarine cable.