Cross-linked polyethylene insulated flame-retardant marine power cable and preparation method thereof

Abstract

The invention discloses a crosslinked polyethylene insulated flame-retardant marine power cable and a preparation method thereof, and relates to the technical field of power cables. The bismuth borate nano powder and the modified polyolefin are blended to serve as the cable material, the aging problem is reduced, and the cable transmission efficiency is improved. Organic-inorganic composite particles are prepared from 1-isopropyl-4-piperidone and zirconium dichloride under the catalysis of concentrated hydrochloric acid through a saturated solution evaporation method, and electromagnetic interference generated by internal signals is shielded; and then mixing with ammonium tripolyphosphate and copper powder, and spraying to the surface of the modified polyethylene insulating layer to form an organic-inorganic shielding layer, thereby enhancing the electromagnetic shielding effect while achieving the anti-aging effect. And the modified polyolefin is prepared by copolymerizing sodium methallyl sulfonate, diethylene glycol dimethacrylate and trivinyl phosphine, and has a stable three-dimensional structure, so that substances with an aging effect are difficult to enter the material, and the anti-aging and flame-retardant properties are enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of power cables, in particular to a cross-linked polyethylene insulated flame-retardant shipboard power cable and a preparation method thereof. Background Art

[0002] In recent years, with the increasing development and popularization of the use of wires and cables in production and life, the demand for wires and cables has increased rapidly, and with the development of the economy, the requirements for their materials have become higher and higher. Cross-linked polyethylene (XLPE) materials with excellent electrical and mechanical properties and low prices are widely used in high-voltage power cable insulation. However, in the development of XLPE DC cable insulation materials, my country started later than foreign countries and has less technical accumulation, and higher voltage insulation materials still need to be imported from foreign countries in large quantities every year. With the continuous increase in my country's demand for power resources, the development of XLPE insulated high-voltage DC cables to higher voltage levels is imperative.

[0003] Although my country has vigorously developed ultra-clean XLPE cable materials for high-voltage cables in recent years, there is still a certain gap between the ultra-clean cable materials for high-voltage and even ultra-high-voltage cables and those for foreign countries. Usually, the flame retardancy of cables is improved by adding flame retardant materials. Inorganic flame retardants and fillers are often used flame retardants. In actual use, the addition of inorganic flame retardants will change the vulcanization properties, physical and mechanical properties, and thermal properties of the rubber. At the same time, these powders are very easy to agglomerate, which directly affects the flame retardant effect of inorganic filler particles. These agglomerated inorganic flame retardants and fillers will greatly cause void defects inside the material, which will lead to a decrease in the overall mechanical properties of the cable material and a decrease in insulation performance. The insulation properties of nano-doped composite dielectric materials can be significantly improved, but this modification mechanism depends to a large extent on the dispersibility of the nano-fillers. It is difficult to obtain nano-doped modified materials with uniform dispersion and stable raw material performance with the current production process. The application of nano-doped modification technology in actual production requires substantial adjustment and optimization of production equipment and processes. In the field of organic molecule grafting modification technology, existing studies have shown that molecules with functional groups are introduced into the polymer matrix by using the grafting process. Deep trap energy levels are introduced inside the XLPE material through the polar groups in the grafted compounds. This can form a uniformly distributed Coulomb force field in the polymer matrix, inhibit carrier transport and electrode charge injection, and effectively avoid the phenomenon of uneven dispersion inside the material. This is more in line with the current status of my country's existing cable production and manufacturing processes and is easy to implement. Summary of the invention

[0004] The object of the present invention is to provide a cross-linked polyethylene insulated flame-retardant shipboard power cable and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a cross-linked polyethylene insulated flame-retardant shipboard power cable, the cross-linked polyethylene insulated flame-retardant shipboard power cable comprises a conductor, a modified polyethylene insulation layer, an organic-inorganic shielding layer, and a sheath layer.

[0006] Furthermore, the modified polyethylene insulation layer comprises, by weight, 55 to 65 parts of cross-linked polyethylene, 30 to 40 parts of modified polyolefin, 13 to 19 parts of bismuth borate nanopowder, and 2 to 4 parts of plasticizer;

[0007] The preparation method of the modified polyolefin is as follows: by weight, in a nitrogen atmosphere, 8 to 14 parts of sodium methacrylate sulfonate, 5 to 11 parts of diethylene glycol dimethacrylate, 4 to 6 parts of trivinyl phosphine, and 64 to 94 parts of toluene are uniformly mixed, 0.1 to 0.3 parts of triisobutylaluminum are added, the temperature is raised to 65 to 85° C., and the mixture is stirred at 130 rpm for reaction for 12 to 26 hours. After the reaction is completed, the mixture is connected to air, cooled naturally to room temperature, filtered to obtain a solid, washed with ethanol for 3 times, and dried in an oven at 30 to 40° C. for 10 to 18 hours to obtain the modified polyolefin.

[0008] Furthermore, the particle size of the bismuth borate nanopowder is 10 to 60 nm.

[0009] Furthermore, the organic-inorganic shielding layer is prepared by preparing composite particles by evaporating 1-isopropyl-4-piperidone and zirconium dichloride under the catalysis of concentrated hydrochloric acid, mixing with ammonium tripolyphosphate and copper powder, and spraying them onto the surface of the modified polyethylene insulation layer.

[0010] Furthermore, a method for preparing a cross-linked polyethylene insulated flame-retardant marine power cable comprises the following preparation steps:

[0011] (1) 55 to 65 parts of cross-linked polyethylene, 30 to 40 parts of modified polyolefin, 13 to 19 parts of bismuth borate nanopowder, and 2 to 4 parts of plasticizer are uniformly mixed, extruded through a mixer, and pelletized to obtain modified polyethylene particles;

[0012] (2) melting and extruding 25 to 75 parts of modified polyethylene particles at 130 to 140° C. to coat a copper conductor to form an insulating layer, thereby obtaining an insulated battery cell;

[0013] (3) 40 to 50 parts of an acrylate binder, 22 to 30 parts of organic-inorganic composite particles, 5 to 9 parts of ammonium tripolyphosphate, 34 to 56 parts of copper nanopowder, and 62 to 84 parts of toluene are mixed uniformly at 50 to 70° C., and sprayed uniformly on the surface of the insulating battery core by a sprayer to form an organic-inorganic shielding layer with a thickness of 0.1 to 0.3 mm. The layer is dried at 40 to 50° C. for 1 to 3 hours, and then cross-linked polyethylene is extruded at 150 to 170° C. on the periphery of the shielding layer, and naturally cooled to room temperature to obtain a cross-linked polyethylene insulated flame-retardant shipboard power cable; the acrylate binder is obtained by copolymerizing 85 to 97% of butyl acrylate and 3 to 15% of acrylic acid.

[0014] Furthermore, the cross-linked polyethylene includes 100 parts by weight of polyethylene with a molecular weight of 50,000 to 100,000, 20 parts by weight of organic peroxide, and 5 parts by weight of poly-1,2-butadiene.

[0015] Furthermore, the plasticizer in step (1) is a mixture of any one or more of dibutyl phthalate, dioctyl phthalate, and chlorinated paraffin.

[0016] Furthermore, the parameters of the mixer in step (1) are: head temperature of 140-150°C, screw speed of 220-240 r / min, extrusion pressure of 6-12 MPa, shear rate of 160-200 s -1 .

[0017] Furthermore, in step (2), the cross-sectional area of ​​the copper conductor is 0.5 to 200 mm2, and the thickness of the insulation layer is 0.4 to 2.0 mm.

[0018] Furthermore, the preparation method of the organic-inorganic composite particles in step (3) is: 14 to 20 parts of 1-isopropyl-4-piperidone, 8 to 14 parts of zirconium dichloride, and 100 to 180 parts of ethanol are mixed evenly, concentrated hydrochloric acid is added until the solution is clarified, filtered with a double-layer filter paper, the solution is collected, and slowly evaporated at 25 to 35° C. for 16 to 20 hours, and the solid is collected to obtain organic-inorganic composite particles.

[0019] Furthermore, the spraying conditions of the sprayer in step (3) are: spray gun moving speed 700-900 mm / s, current 1500A-1600A, and spraying distance 450-550 mm.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] (1) The present invention uses bismuth borate nanopowder and modified polyolefin as cable materials. The bismuth borate nanopowder has good stability, reduces the problem of cable aging caused by environmental factors, and achieves anti-aging performance. At the same time, it has good electrical insulation, can effectively prevent current leakage, reduce power loss, and thus improve the transmission efficiency of the cable. The nanoparticle size structure has a large specific surface area and can be better dispersed in the modified polyolefin, which can further improve the overall stability of the electrical material and enhance the anti-aging effect of the cable.

[0022] (2) The present invention utilizes 1-isopropyl-4-piperidone and zirconium dichloride in the presence of concentrated hydrochloric acid to prepare organic-inorganic composite particles by saturated solution evaporation method, which can effectively shield the electromagnetic interference generated by internal signals, thereby achieving high transmission efficiency performance; the particles are then mixed with ammonium tripolyphosphate and copper powder, sprayed onto the surface of the modified polyethylene insulation layer, and an organic-inorganic shielding layer is formed on the surface through electrostatic bonding, which can inhibit the interaction of active free radicals on the polymer molecular chain, achieve anti-aging effects, and enhance the electromagnetic shielding effect.

[0023] (3) The modified polyolefin is prepared by copolymerization of sodium methacrylate, diethylene glycol dimethacrylate and trivinyl phosphine, and has a stable three-dimensional structure, which makes it difficult for substances with aging effects to enter the interior of the material, thereby enhancing the anti-aging performance. The modified polyolefin contains P and S groups, which synergistically promote the dehydration of plastic particles into carbon. The free radicals such as PO and PO2 produced by pyrolysis can quench active free radicals such as H and OH in the gas phase, thereby preventing the continuation of the chain reaction when the cable burns. It can also prevent heat from transferring into the interior of the material and reduce the generation of combustible gases, thereby achieving a flame retardant effect. In addition, the multiple ether bonds contained in diethylene glycol dimethacrylate can form a stable connection with the composite particles, enhance the interaction between molecular chains, reduce environmental damage to molecular chains, and thus delay cable aging. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of the cross-linked polyethylene insulated flame-retardant marine power cable prepared in the following examples are as follows:

[0026] Tensile strength: Take the same mass of the embodiment and the comparative example, and test them according to GB / T 1040.2. When the corresponding standard value is greater than or equal to 9, refer to the corresponding standard in JB / T 10707-2007. After aging the sample at 100°C for 200h, test it again.

[0027] Flame retardant grade: Take the embodiment and comparative example of the same quality and test them with reference to GB / T 19666-2019.

[0028] Volume resistivity at 20°C: The examples and comparative examples of the same mass were tested according to GB / T 1410-2007.

[0029] Dielectric loss factor, dielectric constant, dielectric strength: the embodiment and comparative example of the same mass were tested in accordance with JB / T10437-2004.

[0030] Shielding efficiency: Take the embodiment and comparative example of the same mass, uniformly spray the shielding layer with a thickness of 0.1 mm, test the shielding efficiency of the cable, and record the results.

[0031] Example 1

[0032] (1) 14 parts of 1-isopropyl-4-piperidone, 8 parts of zirconium dichloride, and 100 parts of ethanol were mixed evenly, concentrated hydrochloric acid was added until the solution was clear, filtered with double-layer filter paper, the solution was collected, and slowly evaporated at 25° C. for 16 hours, and the solid was collected to prepare organic-inorganic composite particles;

[0033] (2) Under a nitrogen atmosphere, 8 parts of sodium methacrylate sulfonate, 5 parts of diethylene glycol dimethacrylate, 4 parts of trivinyl phosphine, and 64 parts of toluene were mixed evenly, 0.1 parts of triisobutylaluminum were added, the temperature was raised to 65° C., and the mixture was stirred at 130 rpm for 12 h. After the reaction was completed, the air was connected, and the mixture was naturally cooled to room temperature. The solid was filtered, washed with ethanol three times, and dried in an oven at 30° C. for 10 h to obtain a modified polyolefin;

[0034] (3) Boric acid and bismuth oxide were mixed in a mass ratio of 1:1.2, 14 parts of the mixed powder were placed in a ball mill, 30 parts of anhydrous ethanol were added, ball milled for 2 hours, dried at 40° C. for 3 hours, and then allowed to stand at 240° C. for 2 hours, and ground into a powder with a particle size of 10 nm to obtain bismuth borate nanopowder;

[0035] (4) 55 parts of cross-linked polyethylene, 30 parts of modified polyolefin, 13 parts of bismuth borate nanopowder, and 2 parts of dibutyl phthalate were mixed uniformly, extruded and pelletized in a mixer at a head temperature of 140° C., a screw speed of 220 r / min, an extrusion pressure of 6 MPa, and a shear rate of 160 s -1 , to obtain modified polyethylene particles;

[0036] (5) 25 parts of modified polyethylene particles were melted and extruded at 130°C to coat a cross-sectional area of ​​0.5 mm 2 The copper conductor is formed into an insulating layer with a thickness of 0.4 mm to obtain an insulated battery core;

[0037] (6) 40 parts of acrylate binder, 22 parts of organic-inorganic composite particles, 5 parts of ammonium tripolyphosphate, 34 parts of copper nanopowder, and 62 parts of toluene were mixed uniformly at 50°C, and sprayed uniformly on the surface of the insulating battery core by a sprayer at a spray gun moving speed of 700 mm / s, a current of 1500 A, and a spraying distance of 450 mm to form a 0.1 mm thick organic-inorganic shielding layer, which was dried at 40°C for 1 h. Subsequently, cross-linked polyethylene was extruded at 150°C on the periphery of the shielding layer and naturally cooled to room temperature to obtain a cross-linked polyethylene insulated flame-retardant marine power cable with a volume resistivity of 6.5×10 14 Ω·m.

[0038] Example 2

[0039] (1) 17 parts of 1-isopropyl-4-piperidone, 11 parts of zirconium dichloride, and 140 parts of ethanol were mixed evenly, concentrated hydrochloric acid was added until the solution was clear, filtered with double-layer filter paper, the solution was collected, and slowly evaporated at 30° C. for 18 hours, and the solid was collected to prepare organic-inorganic composite particles;

[0040] (2) Under a nitrogen atmosphere, 11 parts of sodium methacrylate sulfonate, 8 parts of diethylene glycol dimethacrylate, 5 parts of trivinyl phosphine, and 79 parts of toluene were mixed evenly, 0.2 parts of triisobutylaluminum were added, the temperature was raised to 75° C., and the mixture was stirred at 130 rpm for 19 h. After the reaction was completed, the air was connected, and the mixture was naturally cooled to room temperature. The solid was filtered, washed with ethanol three times, and dried in an oven at 35° C. for 14 h to obtain a modified polyolefin;

[0041] (3) Boric acid and bismuth oxide were mixed in a mass ratio of 1:1.4, 23 parts of the mixed powder was placed in a ball mill, 45 parts of anhydrous ethanol was added, ball milled for 3 hours, dried at 40° C. for 4 hours, and then allowed to stand at 260° C. for 4 hours, and ground into a powder with a particle size of 35 nm to obtain bismuth borate nanopowder;

[0042] (4) 60 parts of cross-linked polyethylene, 35 parts of modified polyolefin, 16 parts of bismuth borate nanopowder, and 3 parts of dioctyl phthalate were mixed uniformly, extruded and pelletized in a mixer at a head temperature of 145° C., a screw speed of 230 r / min, an extrusion pressure of 8 MPa, and a shear rate of 180 s -1 , to obtain modified polyethylene particles;

[0043] (5) 50 parts of modified polyethylene particles were melted and extruded at 135°C to coat a cross-sectional area of ​​100 mm 2 A copper conductor is formed to form an insulating layer with a thickness of 1.2 mm to obtain an insulated battery core;

[0044] (6) 45 parts of acrylate binder, 26 parts of organic-inorganic composite particles, 7 parts of ammonium tripolyphosphate, 45 parts of copper nanopowder, and 73 parts of toluene were mixed uniformly at 60°C, and sprayed uniformly on the surface of the insulating battery core by a sprayer with a spray gun moving speed of 800 mm / s, a current of 1550 A, and a spraying distance of 500 mm to form a 0.2 mm thick organic-inorganic shielding layer, which was dried at 45°C for 2 h. Subsequently, cross-linked polyethylene was extruded at 160°C on the periphery of the shielding layer and naturally cooled to room temperature to obtain a cross-linked polyethylene insulated flame-retardant marine power cable with a volume resistivity of 6.8×10 14 Ω·m.

[0045] Example 3

[0046] (1) 20 parts of 1-isopropyl-4-piperidone, 14 parts of zirconium dichloride, and 180 parts of ethanol were mixed evenly, concentrated hydrochloric acid was added until the solution was clear, filtered with double-layer filter paper, the solution was collected, and slowly evaporated at 35° C. for 20 hours, and the solid was collected to prepare organic-inorganic composite particles;

[0047] (2) Under a nitrogen atmosphere, 14 parts of sodium methacrylate sulfonate, 11 parts of diethylene glycol dimethacrylate, 6 parts of trivinylphosphine, and 94 parts of toluene were mixed evenly, 0.3 parts of triisobutylaluminum were added, the temperature was raised to 85° C., and the mixture was stirred at 130 rpm for 26 h. After the reaction was completed, the air was connected, and the mixture was naturally cooled to room temperature. The solid was filtered, washed with ethanol three times, and dried in an oven at 40° C. for 18 h to obtain a modified polyolefin;

[0048] (3) Boric acid and bismuth oxide were mixed in a mass ratio of 1:1.6, 32 parts of the mixed powder was placed in a ball mill, 60 parts of anhydrous ethanol was added, ball milled for 4 hours, dried at 40° C. for 5 hours, and then allowed to stand at 280° C. for 6 hours, and ground into a powder with a particle size of 60 nm to obtain bismuth borate nanopowder;

[0049] (4) 65 parts of cross-linked polyethylene, 40 parts of modified polyolefin, 19 parts of bismuth borate nanopowder, and 4 parts of chlorinated paraffin were mixed uniformly, extruded and pelletized in a mixer at a head temperature of 150° C., a screw speed of 240 r / min, an extrusion pressure of 12 MPa, and a shear rate of 200 s -1 , to obtain modified polyethylene particles;

[0050] (5) 75 parts of modified polyethylene particles were melted and extruded at 140°C to coat a cross-sectional area of ​​200 mm 2 A copper conductor is formed to form an insulating layer with a thickness of 2.0 mm to obtain an insulated battery core;

[0051] (6) 50 parts of acrylate binder, 30 parts of organic-inorganic composite particles, 9 parts of ammonium tripolyphosphate, 56 parts of copper nanopowder, and 84 parts of toluene were mixed uniformly at 70°C, and sprayed uniformly on the surface of the insulating core by a sprayer at a spray gun moving speed of 900 mm / s, a current of 1600 A, and a spraying distance of 550 mm to form a 0.3 mm thick organic-inorganic shielding layer, which was dried at 50°C for 3 h. Subsequently, cross-linked polyethylene was extruded at 170°C on the periphery of the shielding layer and naturally cooled to room temperature to obtain a cross-linked polyethylene insulated flame-retardant marine power cable with a volume resistivity of 6.6×10 14 Ω·m.

[0052] Comparative Example 1

[0053] The difference between Comparative Example 1 and Example 2 is that bismuth borate nanopowder is not added when preparing the modified polyethylene particles. The remaining steps are the same as in Example 2.

[0054] Comparative Example 2

[0055] The difference between Comparative Example 2 and Example 2 is that no organic-inorganic composite particles are added to the solution during spraying. The remaining steps are the same as Example 2.

[0056] Comparative Example 3

[0057] The difference between Comparative Example 3 and Example 2 is that sodium methacrylate sulfonate is not added when preparing the modified polyolefin. The remaining steps are the same as those of Example 2.

[0058] Comparative Example 4

[0059] The difference between Comparative Example 4 and Example 2 is that diethylene glycol dimethacrylate is not added when preparing the modified polyolefin. The remaining steps are the same as those of Example 2.

[0060] Comparative Example 5

[0061] The difference between Comparative Example 5 and Example 2 is that trivinyl phosphine is not added when preparing the modified polyolefin. The remaining steps are the same as those of Example 2.

[0062] Effect example

[0063] Table 1 below shows the performance analysis results of the cross-linked polyethylene insulated flame-retardant marine power cables of Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

[0064] Table 1

[0065]

[0066]

[0067] From the comparison of the experimental data of Examples 1, 2, and 3 with those of Comparative Example 1, it can be found that by blending bismuth borate nanopowder with modified polyolefin as a cable material, the bismuth borate nanopowder has good stability, can reduce the problem of cable aging caused by environmental factors, achieve anti-aging performance, and at the same time have good electrical insulation, effectively prevent current leakage, reduce power loss, and improve the transmission efficiency of the cable, and the nanoparticle size structure has a large specific surface area, which can achieve good dispersion in the modified polyolefin, further improve the overall stability of the electrical material, and enhance the anti-aging effect of the cable; from the comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 2, it can be found that by using 1-isopropyl-4-piperidone and zirconium dichloride under concentrated hydrochloric acid catalysis, the organic-inorganic composite particles are prepared by saturated solution evaporation method, the composite particles have a higher dielectric constant, can effectively shield the electromagnetic interference generated by the internal signal, and achieve high transmission efficiency performance, and are mixed with polyethylene, ammonium tripolyphosphate, and copper powder, and sprayed on the surface of the modified polyethylene insulation layer, can be electrostatically bonded, An organic-inorganic shielding layer is formed on its surface, which inhibits the interaction of active free radicals on the polymer molecular chain, achieves anti-aging effect and enhances the electromagnetic shielding effect; from the comparison of the experimental data of Examples 1, 2, 3 with Comparative Examples 3, 4, 5, it can be found that the material is copolymerized with sodium methyl methacrylate, diethylene glycol dimethacrylate and trivinyl phosphine, and has a stable three-dimensional structure, which makes it difficult for substances with aging effects to enter the interior of the material, thereby enhancing the anti-aging performance, and the modified polyolefin contains P and S groups, which synergistically promote the dehydration of plastic particles into carbon, and the free radicals such as PO and PO2 generated by pyrolysis can quench the active free radicals such as H and OH in the gas phase, thereby preventing the continuation of the chain reaction when the cable burns, and can also prevent heat from being transferred to the interior of the material, reducing the generation of combustible gases, thereby achieving a flame retardant effect. In addition, the multiple ether bonds contained in diethylene glycol dimethacrylate can form a stable connection with the composite particles, enhance the interaction between molecular chains, reduce environmental damage to molecular chains, and delay cable aging.

[0068] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A cross-linked polyethylene insulated flame-retardant shipboard power cable, characterized in that: The cross-linked polyethylene insulated flame-retardant shipboard power cable comprises a conductor, a modified polyethylene insulation layer, an organic-inorganic shielding layer and a sheath layer.

2. A cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 1, characterized in that: The modified polyethylene insulation layer comprises, by weight, 55 to 65 parts of cross-linked polyethylene, 30 to 40 parts of modified polyolefin, 13 to 19 parts of bismuth borate nanopowder, and 2 to 4 parts of plasticizer; The preparation method of the modified polyolefin is as follows: by weight, in a nitrogen atmosphere, 8 to 14 parts of sodium methacrylate sulfonate, 5 to 11 parts of diethylene glycol dimethacrylate, 4 to 6 parts of trivinyl phosphine, and 64 to 94 parts of toluene are uniformly mixed, 0.1 to 0.3 parts of triisobutylaluminum are added, the temperature is raised to 65 to 85° C., and the mixture is stirred at 130 rpm for reaction for 12 to 26 hours. After the reaction is completed, the mixture is connected to air, cooled naturally to room temperature, filtered to obtain a solid, washed with ethanol for 3 times, and dried in an oven at 30 to 40° C. for 10 to 18 hours to obtain the modified polyolefin.

3. A cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 2, characterized in that: The particle size of the bismuth borate nanopowder is 10-60 nm.

4. A cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 1, characterized in that: The organic-inorganic shielding layer is prepared by preparing composite particles by evaporating 1-isopropyl-4-piperidone and zirconium dichloride under the catalysis of concentrated hydrochloric acid, mixing with ammonium tripolyphosphate and copper powder, and spraying them on the surface of the modified polyethylene insulation layer.

5. A method for preparing a cross-linked polyethylene insulated flame-retardant shipboard power cable, characterized in that: The method comprises the following preparation steps: (1) 55 to 65 parts of cross-linked polyethylene, 30 to 40 parts of modified polyolefin, 13 to 19 parts of bismuth borate nanopowder, and 2 to 4 parts of plasticizer are uniformly mixed, extruded through a mixer, and pelletized to obtain modified polyethylene particles; (2) melting and extruding 25 to 75 parts of modified polyethylene particles at 130 to 140° C. to coat a copper conductor to form an insulating layer, thereby obtaining an insulated battery cell; (3) 40 to 50 parts of acrylic binder, 22 to 30 parts of organic-inorganic composite particles, 5 to 9 parts of ammonium tripolyphosphate, 34 to 56 parts of copper nanopowder, and 62 to 84 parts of toluene are mixed uniformly at 50 to 70° C., and sprayed uniformly on the surface of the insulating battery core by a sprayer to form an organic-inorganic shielding layer with a thickness of 0.1 to 0.3 mm. The organic-inorganic shielding layer is dried at 40 to 50° C. for 1 to 3 hours, and then cross-linked polyethylene is extruded at 150 to 170° C. on the periphery of the shielding layer, and naturally cooled to room temperature to obtain a cross-linked polyethylene insulated flame-retardant shipboard power cable.

6. The method for preparing a cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 5, characterized in that: The plasticizer in step (1) is a mixture of any one or more of dibutyl phthalate, dioctyl phthalate and chlorinated paraffin.

7. The method for preparing a cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 5, characterized in that: The parameters of the mixer in step (1) are: head temperature of 140-150°C, screw speed of 220-240 r / min, extrusion pressure of 6-12 MPa, shear rate of 160-200 s -1 .

8. The method for preparing a cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 5, characterized in that: The cross-sectional area of ​​the copper conductor in step (2) is 0.5 to 200 mm 2 , the thickness of the insulation layer is 0.4~2.0mm.

9. The method for preparing a cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 5, characterized in that: The preparation method of the organic-inorganic composite particles in step (3) is as follows: 14 to 20 parts of 1-isopropyl-4-piperidone, 8 to 14 parts of zirconium dichloride, and 100 to 180 parts of ethanol are mixed evenly, concentrated hydrochloric acid is added until the solution is clarified, filtered with a double-layer filter paper, the solution is collected, and slowly evaporated at 25 to 35° C. for 16 to 20 hours, and the solid is collected to obtain the organic-inorganic composite particles.

10. The method for preparing a cross-linked polyethylene insulated flame-retardant shipboard power cable according to claim 5, characterized in that: The spraying conditions of the sprayer in step (3) are: spray gun moving speed 700-900 mm / s, current 1500A-1600A, and spraying distance 450-550 mm.

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