Long-life nuclear-radiation-resistant low-smoke flame-retardant marine cable sheath material as well as preparation method and application thereof

Abstract

The invention relates to the field of cables, and particularly discloses a long-life nuclear-radiation-resistant low-smoke flame-retardant marine cable sheath material as well as a preparation method and application thereof. The invention relates to a long-life nuclear-radiation-resistant low-smoke flame-retardant marine cable sheath material. Used raw materials comprise the following components: EVA, EBA, EEA, linear low-density polyethylene, low-density polyethylene, maleic anhydride graft, color master batches, an inorganic flame retardant, an organosilicon flame retardant, carbon nanotubes, a surface treating agent, a crosslinking sensitizer, a compound multi-element antioxidant, a light stabilizer, an ultraviolet absorber and a lubricant. The preparation method comprises the following steps: premixing and mixing the raw materials to obtain the sheath material. The sheath material disclosed by the invention can be used for preparing a sheath layer of a cable, has good thermal stability, flame retardance and mechanical properties, is relatively high in tensile strength, tearing strength and elongation at break, and also has excellent performance in a thermal aging test and a mineral oil resistance test.

Description

Technical Field

[0001] This application relates to the technical field of cables, and in particular to a long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material, its preparation method, and its application. Background Technology

[0002] Existing marine cables are prone to aging and have a short service life under nuclear radiation environments. Furthermore, their flame-retardant properties deteriorate in the event of a fire after irradiation, posing a threat to personnel and equipment safety. Under the combined effects of high temperature and radiation, the rate of free radical generation in the cross-linked polyolefin sheath material accelerates, and oxidative degradation and radiation-induced chain scission mutually promote each other, leading to increased embrittlement of the material. In addition, radiation may damage the flame retardant structure, resulting in a decrease in flame-retardant performance. To address these issues with marine cables, existing technologies typically employ high-temperature and radiation-resistant cable products. Some products may resist the effects of radiation and high temperatures by using special high-performance materials, such as polymers with special chemical structures. Other products may achieve cable protection by adding protective structures, such as multiple protective layers, each with different functions, such as heat insulation or radiation blocking. Still other products incorporate special additives during the cable manufacturing process to improve cable performance.

[0003] However, existing marine cables have significant drawbacks. In a nuclear radiation environment, these cables are prone to aging, resulting in a significantly shortened lifespan. Furthermore, their flame-retardant properties deteriorate in the event of a fire after irradiation, posing a serious threat to the safety of personnel and equipment on board. In addition, while some high-temperature and radiation-resistant cables can resist radiation and high temperatures to a certain extent, their complex structures and excessive costs mean that, while meeting the requirements for high-temperature and radiation resistance, their conventional performance cannot meet the corresponding standard requirements. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material, its preparation method, and its application.

[0005] In one aspect, this application provides a long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material. By weight, the raw materials used include the following components: 15-30 parts EVA; 10-25 parts EBA; 12-23 parts EEA; 20-30 parts linear low-density polyethylene; 5-10 parts low-density polyethylene; 5-15 parts maleic anhydride graft; 3-6 parts color masterbatch; 120-180 parts inorganic flame retardant; 3-8 parts organosilicon flame retardant; 2-5 parts carbon nanotubes; 1-2 parts surface treatment agent; 1.2-1.8 parts crosslinking sensitizer; 1.0-2.5 parts compounded multi-element antioxidant; 0.5-1.0 parts light stabilizer; 0.2-0.6 parts ultraviolet absorber; and 0.5-1 part lubricant.

[0006] Preferably, the raw materials used, by weight, include the following components: 20-25 parts EVA; 5-20 parts EBA; 16-18 parts EEA; 25-27 parts linear low-density polyethylene; 6-8 parts low-density polyethylene; 10-12 parts maleic anhydride graft; 3-6 parts color masterbatch; 155-160 parts inorganic flame retardant; 6-7 parts organosilicon flame retardant; 3-4 parts carbon nanotubes; 1-2 parts surface treatment agent; 1.2-1.8 parts crosslinking sensitizer; 1.0-2.5 parts compounded multi-element antioxidant; 0.5-1.0 parts light stabilizer; 0.2-0.6 parts ultraviolet absorber; and 0.5-1 part lubricant.

[0007] Preferably, the inorganic flame retardant comprises magnesium hydroxide and aluminum hydroxide in a weight ratio of 1:2.

[0008] By adopting the above technical solution, this application first uses a compound of ethylene copolymers EVA, EBA, and EEA with long side chain structures, which improves the thermal stability of the sheath material in terms of microstructure. At the same time, its polar groups enhance the compatibility between the resin and flame retardant in the system, improving the flame retardant performance of the sheath. This application also adds linear low-density polyethylene with high crystallinity, large molecular weight, and low melt index. The long polymer segments in its molecular chain can bind the interlayer molecules, increase the number of ligation molecules between crystals, thereby increasing the crystallinity of polyethylene, making the molecular chain arrangement more regular, the density of bonding between grains greater, and the connecting molecules less likely to untangle and loosen at high temperatures. At the same time, the higher the crystallinity, the higher its melting point, thus further ensuring the thermal stability of the material. The inorganic flame retardant, organosilicon flame retardant, and carbon nanotubes in the system can achieve a good synergistic flame retardant effect, giving the material good crusting properties and anti-dripping properties, thereby significantly increasing the flame retardant performance and light transmittance of the material. When the organosilicon flame retardant burns, it generates a unique inorganic heat-insulating protective layer containing -Si-O and -Si-C bonds, which not only prevents the escape of combustion decomposition products but also inhibits the thermal decomposition of polymer materials, achieving the purpose of high flame retardancy, low smoke production, and low toxicity. Carbon nanotubes can promote the formation of a good char layer during combustion, reduce the heat release of the material, and reduce smoke production. At the same time, the nanomaterials are well dispersed during mixing and act as cross-linking grid points in the later irradiation cross-linking process, thereby giving the material a more perfect three-dimensional network structure, improving the mechanical properties and thermal stability of the material, and giving the material a higher long-term service temperature and a longer service life. This application presents an anti-aging and anti-radiation system composed of compounded multi-element antioxidants, ultraviolet light absorbers, and light stabilizers. This system can act on free radicals generated during the aging process, block and slow down the aging process, reduce the increase in loss factor caused by high-temperature aging and gamma-ray radiation, and reduce the generation of internal cracks and micropores in the polymer, thereby giving the material excellent radiation resistance.

[0009] In summary, the sheath material of this application exhibits good thermal stability, flame retardancy, and mechanical properties after molding. According to experimental data, the sheath material has high tensile strength, tear strength, and elongation at break after molding, and also shows excellent performance in thermal aging tests and mineral oil resistance tests.

[0010] Preferably, the inorganic flame retardant further includes SDBS-modified calcined hydrotalcite, and the weight ratio of SDBS-modified calcined hydrotalcite, magnesium hydroxide, and aluminum hydroxide is 1:1:2.

[0011] Optionally, the SDBS-modified calcined hydrotalcite is prepared by the following method: magnesium nitrate, aluminum nitrate and sodium hydroxide are slowly mixed, heated and aged, cooled, filtered, dried and calcined to obtain calcined hydrotalcite. Then, the calcined hydrotalcite is mixed with 1,2-propanediol and reacted. SDBS is then added for modification. After the reaction is completed, the product is washed with 1,2-propanediol, filtered, washed and dried to obtain SDBS-modified calcined hydrotalcite.

[0012] By adopting the above technical solution, this application also adds SDBS-modified calcined hydrotalcite to the inorganic flame retardant. SDBS-modified calcined hydrotalcite has a layered structure, which can enhance the density of the system. Magnesium hydroxide has a high decomposition temperature, which is suitable for high-temperature processing systems. Aluminum hydroxide has a high heat absorption capacity, which can quickly reduce the surface temperature of the material when it is heated. The combination of the three can achieve the three functions of flame retardancy, smoke suppression and thermal stability in one, effectively optimizing the flame retardant performance of the sheath material.

[0013] Preferably, the light stabilizer is a hindered amine light stabilizer.

[0014] By adopting the above technical solution, based on the introduction of SDBS-modified calcined hydrotalcite into the system of this application, hindered amine light stabilizer is also used as a light stabilizer. The nanosheets of SDBS-modified calcined hydrotalcite form a physical barrier layer in the matrix, which can increase the reflectivity of ultraviolet rays to 45-60%, reduce the amount of free radicals generated by the hindered amine light stabilizer, and thus optimize its treatment effect. In addition, SDBS-modified calcined hydrotalcite has the property of decomposition and endothermic reaction at high temperature, which can reduce the surface temperature of the material and extend the effective action time of the hindered amine light stabilizer at high temperature. Therefore, the two have a good synergistic effect, which can optimize the working effect of the anti-aging and anti-radiation system composed of compounded multi-element antioxidants, ultraviolet light absorbers and light stabilizers, so that the material has better radiation resistance.

[0015] Preferably, the compound multi-element antioxidant includes antioxidant 1010, antioxidant 168 and antioxidant 1076 in a weight ratio of 1:2:1.

[0016] By adopting the above technical solution, this application utilizes antioxidants 1010, 168, and 1076 in a weight ratio of 1:2:1. Antioxidants 1010 and 1076 are used as the main antioxidant components. They capture free radicals (RO· / ROO·) through phenolic hydroxyl groups, blocking the oxidation chain reaction and providing long-term thermo-oxidative stability. Antioxidant 168 decomposes hydroperoxides (ROOH), inhibiting thermal degradation during processing and reducing the amount of free radicals generated. The combined use of the three can improve the free radical scavenging efficiency and prolong the oxidation induction period. This optimizes the working effect of the anti-aging and anti-radiation system composed of compounded multi-element antioxidants, ultraviolet light absorbers, and light stabilizers, giving the material superior radiation resistance.

[0017] Preferably, the surface treatment agent includes an aluminate coupling agent and an aminosilane coupling agent.

[0018] Preferably, the weight ratio of the aluminate coupling agent to the aminosilane coupling agent is 1:1.

[0019] By adopting the above technical solution, the surface treatment agent of this application includes an aluminate coupling agent and an aminosilane coupling agent, employing a double-coating method. This increases the interfacial compatibility between the filler (inorganic flame retardant, carbon nanotubes) and the base material (EVA, EBA, EEA, linear low-density polyethylene, and low-density polyethylene) within the system, forming a hydrophobic surface and improving the flame retardant and low-smoke properties of the material. Furthermore, this application controls the weight ratio of the aluminate coupling agent and the aminosilane coupling agent to be 1:1, which allows for a better synergistic effect between the two, further improving the flame retardant and low-smoke properties of the material.

[0020] Secondly, this application provides a method for preparing a long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material, comprising the following steps: premixing the raw materials for 1-2 minutes, and then kneading them at a temperature of 105-115°C for 6-8 minutes to obtain the sheath material.

[0021] By adopting the above technical solution, this application premixes and blends multiple raw materials, enabling each raw material to fully exert its function. The resulting sheath material has good thermal stability, flame retardancy, and mechanical properties, and has a long service life.

[0022] Thirdly, this application provides a long-life, nuclear radiation-resistant, low-smoke, flame-retardant marine cable, comprising a conductor, an insulation layer, a filling layer, a wrapping layer, and a sheath layer arranged sequentially from the inside out. The sheath layer is obtained by extruding the aforementioned sheath material at an extrusion temperature of 130-160°C.

[0023] Optionally, the conductor is made of tin-plated copper wire.

[0024] Optionally, the raw materials used in the insulating layer include low-density polyethylene, linear low-density polyethylene, EVA, antioxidants, copper inhibitors, light stabilizers, lubricants, and crosslinking sensitizers.

[0025] Optionally, the filler layer is made of glass fiber rope.

[0026] Optionally, the material used for the wrapping layer is a low-smoke, halogen-free flame-retardant tape.

[0027] By adopting the above technical solution, the sheath layer of the long-life, radiation-resistant, low-smoke, flame-retardant marine cable of this application is extruded from the above sheath material at a temperature of 130-160℃, giving the marine cable comprehensive performance of long life, radiation resistance, and low smoke flame retardancy. The water immersion insulation resistance at a bending radius of 20D is 18600MΩ·km. Under the 250kGy irradiation aging test, the water immersion insulation resistance at a bending radius of 20D is 16100MΩ·km, and there is no breakdown after being treated at 3.5kV voltage for 5 minutes. The carbonization height is 1.2m in the bundled flame retardant Class A test.

[0028] In summary, this application has the following beneficial technical effects: 1. The sheath material of this application has good thermal stability, flame retardancy and mechanical properties after molding. It has high tensile strength, tear strength and elongation at break. It also has excellent performance in heat aging test (135±2℃, 168h) and mineral oil resistance test (121±2℃, 18h). 2. The preparation method of this application premixes and kneads multiple raw materials, which allows each raw material to play its full role. The resulting sheath material has good thermal stability, flame retardancy and mechanical properties, and has a long service life. 3. The sheath layer of the long-life, radiation-resistant, low-smoke, flame-retardant marine cable of this application is made by extruding the above-mentioned sheath material at a temperature of 130-160℃, which gives the marine cable comprehensive performance of long life, radiation resistance, low smoke, and flame retardancy. The water immersion insulation resistance at a bending radius of 20D is 18600MΩ·km. Under the 250kGy irradiation aging test, the water immersion insulation resistance at a bending radius of 20D is 16100MΩ·km and there is no breakdown after being treated at a voltage of 3.5kV for 5 minutes. The carbonization height is 1.2m in the bundled flame retardant Class A test. Detailed Implementation

[0029] Material source Unless otherwise specified, all raw materials used in this application are commercially available products, specifically: EVA was purchased from DuPont, and its brand name is V422. EBA was purchased from DuPont, and its brand name is 4170. EEA was purchased from Styron, and its brand name is 5986. The low-density polyethylene was purchased from Sinopec, and its grade was 7042. The linear low-density polyethylene was purchased from ExxonMobil, grade 6101XR. Maleic anhydride graft material was purchased from Styron, brand name PP-MAH-5986; The masterbatch was purchased from Cabot, brand number 2014; Aluminum hydroxide was purchased from Rheinheide, brand name LY-SP; Magnesium hydroxide was purchased from Chick, brand name A7; The silicone flame retardant was purchased from Dow Corning, brand name DC-8008; The carbon nanotubes were purchased from Jiangsu Xianfeng, and the grade was 100338. The aluminate coupling agent was purchased from Dongguan Dinghai, brand name dl-411; The aminosilane coupling agent was purchased from Guangzhou Goode, brand name CS-7680; The crosslinking sensitizer was purchased from Guangzhou Jingpu, brand name PL400; Antioxidant 1010, Antioxidant 168 and Antioxidant 1076 were purchased from Liansheng Chemical. The light stabilizer was purchased from Guangzhou Shanghe, brand name HS-944, a polymeric high molecular weight hindered amine light stabilizer; The ultraviolet absorber was purchased from Lianlong, brand name UV329; The lubricant is PE wax, purchased from Qihong Polymer, brand name S3816. Antioxidant FL800 was purchased from BASF; Zinc phosphate, an inorganic passivating agent, was purchased from Shandong Chengshun Chemical Co., Ltd. Copper inhibitor, purchased from BASF, brand name 1024; Disodium ethylenediamine acetate, an organic chelating agent, was purchased from Jinan Xinlong Chemical Co., Ltd. The antioxidant was purchased from Kejuya, brand name 445; SDBS-modified calcined hydrotalcite is prepared by the following method: First, weigh magnesium nitrate and aluminum nitrate in a molar ratio of 2:1 and dissolve them in deionized water. Separately, dissolve an equal amount of NaOH in deionized water. Add both solutions dropwise simultaneously. After the addition is complete, continue stirring for 1 hour. The resulting white solution is aged at 75°C for 24 hours, cooled to room temperature, and then filtered. The resulting filter cake is repeatedly washed with deionized water several times, dried at 70°C for 12 hours, ground, and calcined at 300°C for 3 hours to obtain calcined hydrotalcite. Hydrotalcite was dissolved in 1,2-propanediol and stirred at high speed at 65°C to form a homogeneous slurry. Nitric acid was added, and the mixture was stirred for 1 hour. Then, SDBS was gradually added, and the mixture was stirred at room temperature for 3 hours. After the reaction was completed, the mixture was filtered and washed twice with 1,2-propanediol. After filtration and washing, the mixture was dried in an oven at 65°C for 24 hours to obtain SDBS-modified calcined hydrotalcite. The weight ratio of calcined hydrotalcite, SDBS, and nitric acid was controlled to be 1:0.15:2.2 during the reaction.

[0030] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0031] Example 1.1 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheathing material is prepared by the following steps: EVA, EBA, EEA, linear low-density polyethylene, low-density polyethylene, maleic anhydride graft, color masterbatch, inorganic flame retardant, organosilicon flame retardant, carbon nanotubes, surface treatment agent, crosslinking sensitizer, compound multi-component antioxidant, light stabilizer, ultraviolet light absorber, and lubricant are formulated according to the components and dosages in Table 1, premixed for 2 minutes, and then kneaded at 105°C for 8 minutes to obtain the sheath material.

[0032] Example 1.2 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheathing material is prepared by the following steps: EVA, EBA, EEA, linear low-density polyethylene, low-density polyethylene, maleic anhydride graft, color masterbatch, inorganic flame retardant, organosilicon flame retardant, carbon nanotubes, surface treatment agent, crosslinking sensitizer, compound multi-component antioxidant, light stabilizer, ultraviolet light absorber, and lubricant are formulated according to the components and dosages in Table 1, premixed for 1 min, and then kneaded at 115℃ for 6 min to obtain the sheath material.

[0033] Examples 1.3-1.4 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.1 in that the amount of raw materials used is different, as shown in Table 1. All other aspects are the same as in Example 1.1.

[0034] Table 1. Raw material components and dosages used in Examples 1.1-1.4 Example 2.1 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that the inorganic flame retardant consists of 22.9 kg of SDBS-modified calcined hydrotalcite, 45.7 kg of magnesium hydroxide, and 91.4 kg of aluminum hydroxide, while the rest is the same as in Example 1.3.

[0035] Example 2.2 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that the inorganic flame retardant is composed of 40 kg of SDBS-modified calcined hydrotalcite, 40 kg of magnesium hydroxide, and 80 kg of aluminum hydroxide, while the rest is the same as in Example 1.3.

[0036] Example 2.3 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that the inorganic flame retardant consists of 64 kg of SDBS-modified calcined hydrotalcite, 32 kg of magnesium hydroxide, and 64 kg of aluminum hydroxide, while the rest is the same as in Example 1.3.

[0037] Example 2.4 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that the inorganic flame retardant consists of 80 kg of SDBS-modified calcined hydrotalcite, 26.7 kg of magnesium hydroxide, and 53.3 kg of aluminum hydroxide, while the rest is the same as in Example 1.3.

[0038] Example 2.5 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheathing material differs from Example 1.3 in that all magnesium hydroxide is replaced with SDBS-modified calcined hydrotalcite, while the rest is the same as in Example 1.3.

[0039] Example 2.6 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheathing material differs from Example 1.3 in that all aluminum hydroxide is replaced with SDBS-modified calcined hydrotalcite, while the rest is the same as in Example 1.3.

[0040] Example 3.1 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that: the amount of antioxidant 1010 is 0.5 kg, the amount of antioxidant 168 is 1.5 kg, and the amount of antioxidant 1076 is 0.5 kg, while the rest are the same as in Example 1.3.

[0041] Example 3.2 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that: the amount of antioxidant 1010 is 0.8 kg, the amount of antioxidant 168 is 0.9 kg, and the amount of antioxidant 1076 is 0.8 kg, while the rest are the same as in Example 1.3.

[0042] Example 4.1 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that all silane coupling agents are replaced with aluminate coupling agents, while the rest are the same as in Example 1.3.

[0043] Example 4.2 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that all silane coupling agents are replaced with aminosilane coupling agents, while the rest are the same as in Example 1.3.

[0044] Example 4.3 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material differs from Example 1.3 in that the silane coupling agent is replaced with 0.5 kg of aluminate coupling agent and 1.5 kg of aminosilane coupling agent, while the rest is the same as in Example 1.3.

[0045] Example 4.4 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheathing material differs from Example 1.3 in that the silane coupling agent is replaced with 1 kg of aluminate coupling agent and 1 kg of aminosilane coupling agent, while the rest is the same as in Example 1.3.

[0046] Example 4.5 A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheathing material differs from Example 1.3 in that the silane coupling agent is replaced with 1.5 kg of aluminate coupling agent and 0.5 kg of aminosilane coupling agent, while the rest is the same as in Example 1.3.

[0047] Comparative Example 1.1 The difference from Example 1.1 is that EVA is removed, the amount of EBA is 35kg, and the amount of EEA is 17kg. Everything else is the same as in Example 1.1.

[0048] Comparative Example 1.2 The difference from Example 1.1 is that EBA is removed, the amount of EVA is 30kg, and the amount of EEA is 22kg. All other aspects are the same as in Example 1.1.

[0049] Comparative Example 1.3 The difference from Example 1.1 is that EEA is removed, the amount of EBA is 33kg, and the amount of EVA is 19kg. All other aspects are the same as in Example 1.1.

[0050] Comparative Example 2.1 The difference from Example 1.1 is that the amount of compound multi-element antioxidant is 0.5 kg, the amount of light stabilizer is 1.5 kg, and the amount of ultraviolet absorber is 0.1 kg, while the rest are the same as in Example 1.1.

[0051] Comparative Example 2.2 The difference from Example 1.1 is that the amount of compound multi-element antioxidant is 3 kg, the amount of light stabilizer is 0.2 kg, and the amount of ultraviolet absorber is 0.8 kg, while the rest are the same as in Example 1.1.

[0052] Performance testing The performance of the molded sheath material samples was tested. in: The thermal aging test was conducted at a temperature of 135±2℃ for 168 hours. The mineral oil resistance test was conducted at a temperature of 121±2℃ for 18 hours.

[0053] Table 2.1 Performance Test Table-1 Data Analysis: As can be seen from Table 2.1, the marine cable sheath material obtained in Examples 1.1-1.4 of this application has a tensile strength of 12.0-12.7 MPa, an elongation at break of 200-260%, and a tear strength of 6.7-7.0 N / mm after molding. It exhibits excellent performance in the thermal aging test (135±2℃, 168h), with the change rate of tensile strength after aging not exceeding 8% and the change rate of elongation at break not exceeding 7%. It also exhibits excellent performance in the mineral oil resistance test (121±2℃, 18h), with the change rate of tensile strength not exceeding 44% and the change rate of elongation at break not exceeding 28%. It is evident that the sheath material of this application has good thermal stability, flame retardancy, and mechanical properties after molding.

[0054] The adjustment between Examples 2.1-2.6 and Example 1.3 is that the composition of the inorganic flame retardant has been changed. The results show that the change rate of tensile strength and elongation at break after aging in Examples 2.1-2.4 is reduced. However, the change rate of tensile strength and elongation at break after aging in Examples 2.5-2.6 is increased compared with Example 1.3. It can be seen that the SDBS modified calcined hydrotalcite of this application can enhance the density of the system by virtue of its layered structure. Magnesium hydroxide has a high decomposition temperature and is suitable for high-temperature processing systems. Aluminum hydroxide has a high heat absorption and can quickly reduce the surface temperature of the material when it is heated. The combination of the three can achieve the three functions of flame retardancy, smoke suppression and thermal stability in one, and there is a good synergistic effect among the three, which effectively optimizes the flame retardant performance of the sheath material.

[0055] The adjustment between Examples 4.1-4.5 and Example 1.3 lies in the change of the surface treatment agent composition. Results show that the changes in tensile strength and elongation at break after aging are reduced in Examples 4.3-4.5, while the overall data for Examples 4.1-4.2 show no significant difference from Example 1.3. This indicates that the surface treatment agent of this application, comprising an aluminate coupling agent and an aminosilane coupling agent, employs a double-coating method, increasing the interfacial compatibility between the filler (inorganic flame retardant, carbon nanotubes) and the base material (EVA, EBA, EEA, linear low-density polyethylene, and low-density polyethylene), forming a hydrophobic surface, and improving the flame retardant and low-smoke properties of the material. Furthermore, this application controls the weight ratio of the aluminate coupling agent and the aminosilane coupling agent to 1:1, which allows for better synergistic effects between the two, further improving the flame retardant and low-smoke properties of the material.

[0056] Comparative Examples 1.1-1.3, which removed EVA, EBA, and EEA respectively, showed a significant decline in overall data. This demonstrates that the use of ethylene copolymers EVA, EBA, and EEA with long side chain structures in this application improves the thermal stability of the sheath material in terms of microstructure, enhances the compatibility between the resin and flame retardant in the system with polar groups, and improves the flame retardant performance of the sheath.

[0057] Application examples A long-life, nuclear radiation-resistant, low-smoke, flame-retardant marine cable is manufactured using the following method: First, tin-plated copper wires are stranded to form a conductor. The tin plating process is electroplating, with a tin layer thickness of (1.0~1.5)μm. The conductor structure consists of 7 wires × each wire with a nominal diameter of 0.52mm. The conductor is stranded using a 1+6 regular stranding structure with a stranding pitch ratio of 16 times and an outer diameter of 1.56mm. Then 80kg of low-density polyethylene, 10kg of linear low-density polyethylene, and 10kg of... EVA, 2kg antioxidant 1010, 4kg antioxidant FL800, 2kg antioxidant 168, 4kg light stabilizer 531, 2kg copper inhibitor 1024, 1kg inorganic passivator zinc phosphate, 1kg organic chelating agent and antioxidant 445 are put into a mixer and thoroughly mixed for 10 minutes. Then, the mixture is put into a reciprocating extrusion granulator (BUSS) for extrusion granulation. After water cooling and drying, cross-linked polyethylene insulation material is produced. The insulation layer is produced by tube extrusion. The nominal thickness of the insulation layer is 0.7mm. The core / sleeve diameter is 3.0mm / 6.0mm. The extrusion temperature is 160℃, 170℃, 175℃, 180℃, 185℃, 190℃, 200℃, 210℃. After extrusion, segmented cooling is used. The outer diameter of the insulated wire core after extrusion is 2.75mm. It is cross-linked by irradiation. The irradiation process is to control the thermal elongation at 30%-50% with energy. The wire core is twisted and filled with fiberglass rope on the side to obtain a filling layer, and then wrapped with a layer of low smoke halogen-free flame retardant tape with a nominal thickness of 0.2mm to obtain a wrapping layer; The sheath layer is produced by extrusion, using the sheath material obtained in Example 1. The nominal thickness of the sheath layer is 1.0 mm, with a core / sleeve diameter of 8.3 mm / 10.6 mm. Extrusion temperatures are 130℃, 140℃, 145℃, 150℃, 160℃, 160℃, and 160℃. Segmented cooling is used after extrusion to ensure good crystallinity of the sheath material. The outer diameter of the extruded sheath core is 10.7 mm. During production, the processing temperature and time are controlled, along with the corresponding processing speed and screw rotation speed (traction speed 30 m / min, screw rotation speed 20 r / min), to avoid excessively high temperatures and excessively long processing times that could lead to material degradation. Radiation crosslinking is used, and to ensure that oil resistance and tear resistance meet requirements, the thermal elongation is controlled at 20%-30%. After finishing, a long-life, nuclear radiation-resistant, low-smoke, flame-retardant marine cable is obtained.

[0058] Performance testing The long-life, nuclear radiation-resistant, low-smoke, flame-retardant marine cables obtained in the corresponding use cases were tested. The 50-year life thermal aging test (155℃, 895h) and the irradiation aging test (250kGy) were both carried out according to the recorded parameters.

[0059] Table 2.2 Performance Test Table-2 Data Analysis: As can be seen from Table 2.2, the long-life, radiation-resistant, low-smoke, flame-retardant marine cable made from the sheath material obtained in the embodiments of this application has a water immersion insulation resistance of 18600 MΩ·km at a bending radius of 20D, a water immersion insulation resistance of 16100 MΩ·km at a bending radius of 20D under a 250kGy irradiation aging test, and no breakdown after 5 minutes of treatment at a voltage of 3.5kV. In the bundled flame retardant Class A test, the carbonization height is 1.2m, demonstrating comprehensive performance of long life, radiation resistance, and low smoke flame retardancy.

[0060] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material, characterized in that, The raw materials used, by weight, include the following components: 15-30 portions of EVA; EBA 10-25 servings; EEA 12-23 copies; 20-30 parts of linear low-density polyethylene; 5-10 parts of low-density polyethylene; 5-15 parts of maleic anhydride graft; 3-6 parts of color masterbatch; 120-180 parts of inorganic flame retardant; 3-8 parts of organosilicon flame retardant; 2-5 parts carbon nanotubes; 1-2 parts of surface treatment agent; Crosslinking sensitizer 1.2-1.8 parts; 1.0-2.5 parts of compound multi-antioxidant; Light stabilizer 0.5-1.0 parts; 0.2-0.6 parts of ultraviolet absorber; 0.5-1 part lubricant.

2. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 1, characterized in that, The raw materials used, by weight, include the following components: 20-25 parts EVA; 15-20 EBA portions; EEA 16-18 copies; 25-27 parts of linear low-density polyethylene; 6-8 parts of low-density polyethylene; 10-12 parts of maleic anhydride graft; 3-6 parts of color masterbatch; 155-160 parts of inorganic flame retardant; 6-7 parts of silicone flame retardant; 3-4 parts of carbon nanotubes; 1-2 parts of surface treatment agent; Crosslinking sensitizer 1.2-1.8 parts; 1.0-2.5 parts of compound multi-antioxidant; Light stabilizer 0.5-1.0 parts; 0.2-0.6 parts of ultraviolet absorber; 0.5-1 part lubricant.

3. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 1, characterized in that, The inorganic flame retardant comprises magnesium hydroxide and aluminum hydroxide in a weight ratio of 1:

2.

4. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 3, characterized in that, The inorganic flame retardant also includes SDBS-modified calcined hydrotalcite, and the weight ratio of SDBS-modified calcined hydrotalcite, magnesium hydroxide, and aluminum hydroxide is 1:1:

2.

5. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 4, characterized in that, The light stabilizer is a hindered amine light stabilizer.

6. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 1, characterized in that, The compound multi-element antioxidants include antioxidant 1010, antioxidant 168, and antioxidant 1076 in a weight ratio of 1:2:

1.

7. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 1, characterized in that, The surface treatment agent includes aluminate coupling agents and aminosilane coupling agents.

8. The long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to claim 7, characterized in that, The weight ratio of the aluminate coupling agent to the aminosilane coupling agent is 1:

1.

9. A method for preparing a long-life, radiation-resistant, low-smoke, flame-retardant marine cable sheath material according to any one of claims 1-8, characterized in that, The process includes the following steps: premixing the raw materials for 1-2 minutes, and then kneading them at 105-115℃ for 6-8 minutes to obtain the sheath material.

10. A long-life, nuclear radiation-resistant, low-smoke, flame-retardant marine cable, characterized in that... It includes a conductor, an insulating layer, a filling layer, a wrapping layer, and a sheath layer arranged sequentially from the inside out. The sheath layer is obtained by extruding the sheath material according to any one of claims 1-8 at an extrusion temperature of 130-160°C.

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