An extruded insulation low voltage power cable and a method for manufacturing the same

Abstract

The application relates to the technical field of cables, and discloses an extruded insulation low-voltage power cable and a preparation method thereof. Copper rods are annealed by wire drawing to obtain copper wires, and the copper wires are twisted to form a copper wire core. Insulating material is extruded on the outer periphery of the copper wire core, cross-linked, and formed into an insulating layer to obtain a cable. An inner lining layer is wrapped on the outer surface of the cable, and an outer sheath is wrapped on the outer periphery of the inner lining layer to obtain the extruded insulation low-voltage power cable. The extruded insulation low-voltage power cable has good tensile, antibacterial and flame-retardant effects.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, in particular to an extruded insulated low-voltage power cable and a preparation method thereof. Background Art

[0002] With the continuous development of urban power grids and the widespread use of distributed energy, low-voltage power cables, as a crucial component of power transmission and distribution systems, have become increasingly important. Their performance and quality play a crucial role in ensuring the reliability and safety of power supply. Traditional low-voltage power cables suffer from deficiencies in insulation materials and flame retardancy. For example, the high dielectric constant of the insulation material leads to high cable capacitance, which not only increases energy loss but also affects signal transmission quality. Conventional cables are prone to combustion in extreme situations, such as fires, releasing large amounts of harmful gases, posing a serious threat to personal safety and equipment. Therefore, preventing this phenomenon is crucial to solving the problem. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the deficiencies in the prior art, the present invention provides an extruded insulated low-voltage power cable and a preparation method thereof, which has good tensile, antibacterial and flame retardant effects.

[0005] (2) Technical solution

[0006] To achieve the above object, the present invention provides the following technical solution: an extruded insulated low-voltage power cable, comprising the following components by weight: a copper wire core, an insulating material, an inner lining layer, and an outer sheath;

[0007] The insulating material comprises the following components by weight: 80-100 parts by weight of low-density polyethylene and 1-3 parts by weight of nano-grade zinc oxide;

[0008] The inner lining layer is made of polyvinyl chloride wrapping tape;

[0009] The outer sheath comprises the following components by weight: 85-120 parts by weight of polyvinyl chloride, 8-15 parts by weight of quaternary ammonium salt modified copolyester, 10-16 parts by weight of o-phenylphenol, and 1-3 parts by weight of talc powder; the particle size of the talc powder is 20 nm.

[0010] Furthermore, the preparation method of the quaternary ammonium salt modified copolyester is:

[0011] S1. Add N,N'-dimethylethylenediamine and 1,4-butane sultone to a reactor containing acetonitrile solvent, stir and mix, then add dropwise a 2-5% by mass fraction of sodium hydroxide solution, react at 65-80°C for 3-5 hours, and then concentrate under reduced pressure to remove the solvent, wash, and dry to obtain a tertiary amino-modified sodium sulfonate;

[0012] S2. To the reactor were added 12.1-12.8 g of octamethylcyclotetrasiloxane, 1-1.5 g of 1,3-diglycidyloxypropyl-1,1,3,3-tetramethyldisiloxane, and under a nitrogen atmosphere, 11-12 mg of tetramethylammonium hydroxide catalyst was added, the temperature was raised to 110-115 ° C for 4-5 h, and then the temperature was raised to 135-140 ° C for 1-1.5 h, the material was cooled, filtered and dried to obtain a double-ended epoxy silicone oil;

[0013] S3. Add double-terminal epoxy silicone oil and tertiary amino-modified sodium sulfonate to tetrahydrofuran solvent, then add tetrabutylammonium bromide catalyst, heat to 55-60 ° C, carry out quaternization reaction, and then rotary distillation and silica gel column chromatography separation, the eluent is a mixed solution of petroleum ether and ethyl acetate, gradient elution to obtain hydroxyl-modified double-terminal sodium sulfonate;

[0014] S4. Add glycolide, ε-caprolactone, hydroxyl-modified double-ended sodium sulfonate and 1,4-butanediol to a three-necked flask filled with chloroform, introduce inert gas for protection at 90-100°C, stir for 20-25 minutes, raise the temperature to 180-200°C, continue to add stannous octoate catalyst, react for 2-4 hours to obtain the product, and then wash to obtain a quaternary ammonium salt-modified copolyester.

[0015] Furthermore, the usage ratio of N,N'-dimethylethylenediamine, 1,4-butanesultone, and sodium hydroxide solution in S1 is 1.13-1.26 g: 2.3-2.7 g: 3-6 mL.

[0016] Furthermore, the mass ratio of the double-ended epoxy silicone oil, the tertiary amino-modified sodium sulfonate, and the tetrabutylammonium bromide catalyst in S3 is 1g:1.85-2.14g:0.01-0.015g.

[0017] Furthermore, the reaction time in S3 is 4-6 hours.

[0018] Furthermore, the inert gas in S4 is nitrogen.

[0019] Furthermore, the mass ratio of glycolide, ε-caprolactone, hydroxyl-modified double-ended sodium sulfonate, 1,4-butanediol, and stannous octoate in S4 is 3.1-3.2g:1g:0.1-0.14g:0.12-0.13g:0.01-0.02g.

[0020] Furthermore, the stirring rate in S4 is 300-310 r / min.

[0021] Furthermore, the preparation method of the extruded insulated low-voltage power cable is:

[0022] Step 1: The copper rod is drawn and annealed to obtain copper wire, and multiple copper wires are twisted to form a copper wire core;

[0023] Step 2: Extruding the insulating material around the outer periphery of the copper wire core, and cross-linking the insulating material to form an insulating layer to obtain a cable;

[0024] Step 3: Wrap an inner lining layer around the outer surface of the cable, and then wrap an outer sheath around the outer periphery of the inner lining layer to obtain an extruded insulated low-voltage power cable.

[0025] Furthermore, the outer sheath is prepared by mixing polyvinyl chloride, quaternary ammonium salt modified copolyester, o-phenylphenol and talc, kneading at 160-170° C. for 3-5 minutes, and forming the outer sheath.

[0026] (3) Beneficial technical effects

[0027] The present invention prepares copper wires by drawing and annealing copper rods, and twists multiple copper wires to form a copper wire core; extrudes an insulating material around the outer periphery of the copper wire core, and cross-links the insulating material to form an insulating layer to prepare a cable; wraps an inner lining layer around the outer surface of the cable, and then wraps an outer sheath around the outer periphery of the inner lining layer to prepare an extruded insulated low-voltage power cable.

[0028] The chains of quaternary ammonium salt-modified copolyester in the outer sheath of extruded insulated low-voltage power cable will be entangled with polyvinyl chloride, and the connection between them will be tighter. When subjected to external force, the energy is dispersed to various fulcrums, which has a better stretching effect; the silicon element contained in it can produce a glass-like substance on the surface of the material when heated, which isolates material transport and energy transfer and has a good flame retardant effect. Sodium sulfonate can promote the release of carbon dioxide and water when burned, accelerate the carbonization rate of polymer molecules, and promote the cross-linking of polymer molecules. These processes help to improve the flame retardancy of the material; the quaternary ammonium salt contained in it has a good antibacterial effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the H NMR spectrum of tertiary amine modified sodium sulfonate. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] In Examples 1-3 and Comparative Examples 1-3, the diameter of the copper wire core is 1 mm, the thickness of the insulating material is 1.2 mm, the thickness of the inner lining layer is 1.5 mm, and the thickness of the outer sheath is 5 mm.

[0033] Example 1

[0034] An extruded insulated low-voltage power cable comprises the following weight components: a copper wire core, an insulating material, an inner lining layer, and an outer sheath;

[0035] The insulating material comprises the following components by weight: 80 parts by weight of low-density polyethylene and 1 part by weight of nano-grade zinc oxide;

[0036] The inner lining layer is made of polyvinyl chloride wrapping tape;

[0037] The outer sheath comprises the following components by weight: 85 parts by weight of polyvinyl chloride, 8 parts by weight of quaternary ammonium salt modified copolyester, 10 parts by weight of o-phenylphenol, and 1 part by weight of talc.

[0038] The preparation method of the quaternary ammonium salt modified copolyester is:

[0039] S1. Add 1.13 g of N,N'-dimethylethylenediamine and 2.3 g of 1,4-butane sultone to a reactor containing 50 mL of acetonitrile solvent and stir to mix. Then, add 3 mL of a 2% sodium hydroxide solution dropwise. The mixture is reacted at 65°C for 3 h. After reaction, the mixture is concentrated under reduced pressure to remove the solvent, washed, and dried to obtain a tertiary amino group-modified sodium sulfonate. The reaction is as follows:

[0040]

[0041] S2. To the reactor was added 12.1 g of octamethylcyclotetrasiloxane, 1 g of 1,3-diglycidyloxypropyl-1,1,3,3-tetramethyldisiloxane, and under a nitrogen atmosphere, 11 mg of tetramethylammonium hydroxide catalyst was added. The temperature was raised to 110 ° C for 4 h, then raised to 135 ° C for 1 h, the material was cooled, filtered and dried to obtain a double-ended epoxy silicone oil;

[0042] S3. To 45 mL of tetrahydrofuran solvent, 1 g of double-terminal epoxy silicone oil and 1.85 g of tertiary amino-modified sodium sulfonate were added, followed by the addition of 0.01 g of tetrabutylammonium bromide catalyst. The temperature was raised to 55°C and the quaternization reaction was carried out for 4 h. After completion, rotary distillation and silica gel column chromatography were performed to separate the mixture using a mixed solution of petroleum ether and ethyl acetate as the eluent, and gradient elution was performed to obtain hydroxyl-modified double-terminal sodium sulfonate;

[0043] S4. Add 3.1 g of glycolide, 1 g of ε-caprolactone, 0.1 g of hydroxyl-modified sodium double-ended sulfonate and 0.12 g of 1,4-butanediol into a three-necked flask containing 40 mL of chloroform, introduce nitrogen at 90°C for protection, stir for 20 minutes at a stirring rate of 300 r / min, raise the temperature to 180°C, and continue to add 0.01 g of stannous octoate catalyst, stir and react for 2 hours to obtain the product, which is then washed to obtain a quaternary ammonium salt-modified copolyester.

[0044] The preparation method of the extruded insulated low-voltage power cable is as follows:

[0045] Step 1: annealing the copper rod by drawing to obtain copper wire, and twisting multiple copper wires to form a copper wire core;

[0046] Step 2: Extruding the insulating material around the outer periphery of the copper wire core, and forming an insulating layer through cross-linking to obtain a cable; the specific steps are: adding the insulating material to the extruder hopper, and gradually plasticizing and melting the insulating material in the barrel through the rotation of the screw and the heating effect of the heating system. The temperature setting of the extruder is successively increased from the feeding section to the head section, which is 120, 150 ° C, and 180 ° C to ensure that the material is fully plasticized and has good fluidity. A mold is installed at the extruder head. The shape of the mold core and the mold sleeve in the mold matches the size and shape of the cable insulation layer. When the insulating material is melted, it is extruded through the annular gap between the mold core and the mold sleeve under a certain pressure, and tightly wrapped around the outside of the copper wire core to form an insulating layer.

[0047] Step 3: Wrap an inner lining layer around the outer surface of the cable, and then wrap an outer sheath around the outer periphery of the inner lining layer to obtain an extruded insulated low-voltage power cable.

[0048] The outer sheath is prepared by mixing polyvinyl chloride, quaternary ammonium salt modified copolyester, o-phenylphenol and talcum powder, kneading at 160° C. for 3 minutes, and forming the outer sheath.

[0049] Example 2

[0050] An extruded insulated low-voltage power cable comprises the following weight components: a copper wire core, an insulating material, an inner lining layer, and an outer sheath;

[0051] The insulating material comprises the following components by weight: 100 parts by weight of low-density polyethylene and 3 parts by weight of nano-grade zinc oxide;

[0052] The inner lining layer is made of polyvinyl chloride wrapping tape;

[0053] The outer sheath comprises the following components by weight: 120 parts by weight of polyvinyl chloride, 15 parts by weight of quaternary ammonium salt modified copolyester, 16 parts by weight of o-phenylphenol, and 3 parts by weight of talc.

[0054] The preparation method of the quaternary ammonium salt modified copolyester is:

[0055] S1. Add 1.26 g of N,N'-dimethylethylenediamine and 2.7 g of 1,4-butane sultone to a reactor containing 60 mL of acetonitrile solvent and stir to mix. Then, add 6 mL of a 5% sodium hydroxide solution dropwise. The mixture is reacted at 80°C for 3 h. After reaction, the solvent is removed by concentration under reduced pressure, washed, and dried to obtain a tertiary amino-modified sodium sulfonate.

[0056] S2. To the reactor were added 12.8 g of octamethylcyclotetrasiloxane, 1.5 g of 1,3-diglycidyloxypropyl-1,1,3,3-tetramethyldisiloxane, and 12 mg of tetramethylammonium hydroxide catalyst under nitrogen atmosphere. The reaction temperature was raised to 115 ° C for 5 h, then raised to 140 ° C for 1.5 h, the material was cooled, filtered and dried to obtain a double-ended epoxy silicone oil;

[0057] S3. To 65 mL of tetrahydrofuran solvent, 1 g of double-terminal epoxy silicone oil and 2.14 g of tertiary amino-modified sodium sulfonate were added, followed by the addition of 0.015 g of tetrabutylammonium bromide catalyst. The temperature was raised to 60°C and the quaternization reaction was carried out for 6 h. After completion, rotary distillation and silica gel column chromatography were performed to separate the mixture using a mixed solution of petroleum ether and ethyl acetate as the eluent, and gradient elution was performed to obtain hydroxyl-modified double-terminal sodium sulfonate;

[0058] S4. Add 3.2 g of glycolide, 1 g of ε-caprolactone, 0.14 g of hydroxyl-modified sodium double-ended sulfonate and 0.13 g of 1,4-butanediol into a three-necked flask containing 50 mL of chloroform, introduce nitrogen at 100°C for protection, stir for 25 minutes at a stirring rate of 310 r / min, raise the temperature to 200°C, and continue to add 0.02 g of stannous octoate catalyst, stir and react for 4 hours to obtain the product, which is then washed to obtain a quaternary ammonium salt-modified copolyester.

[0059] The preparation method of the extruded insulated low-voltage power cable is as follows:

[0060] Step 1: annealing the copper rod by drawing to obtain copper wire, and twisting multiple copper wires to form a copper wire core;

[0061] Step 2: Extruding the insulating material around the outer periphery of the copper wire core, and forming an insulating layer through cross-linking to obtain a cable; the specific steps are: adding the insulating material to the extruder hopper, and gradually plasticizing and melting the insulating material in the barrel through the rotation of the screw and the heating effect of the heating system. The temperature setting of the extruder is successively increased from the feeding section to the head section, which is 120, 150 ° C, and 180 ° C to ensure that the material is fully plasticized and has good fluidity. A mold is installed at the extruder head. The shape of the mold core and the mold sleeve in the mold matches the size and shape of the cable insulation layer. When the insulating material is melted, it is extruded through the annular gap between the mold core and the mold sleeve under a certain pressure, and tightly wrapped around the outside of the copper wire core to form an insulating layer.

[0062] Step 3: Wrap an inner lining layer around the outer surface of the cable, and then wrap an outer sheath around the outer periphery of the inner lining layer to obtain an extruded insulated low-voltage power cable.

[0063] The outer sheath is prepared by mixing polyvinyl chloride, quaternary ammonium salt modified copolyester, o-phenylphenol and talcum powder, kneading at 170° C. for 5 minutes, and forming the outer sheath.

[0064] Example 3

[0065] An extruded insulated low-voltage power cable comprises the following weight components: a copper wire core, an insulating material, an inner lining layer, and an outer sheath;

[0066] The insulating material comprises the following components by weight: 90 parts by weight of low-density polyethylene and 2 parts by weight of nano-grade zinc oxide;

[0067] The inner lining layer is made of polyvinyl chloride wrapping tape;

[0068] The outer sheath comprises the following components by weight: 110 parts by weight of polyvinyl chloride, 12 parts by weight of quaternary ammonium salt modified copolyester, 13 parts by weight of o-phenylphenol, and 2 parts by weight of talc.

[0069] The preparation method of the quaternary ammonium salt modified copolyester is:

[0070] S1. Add 1.19 g of N,N'-dimethylethylenediamine and 2.5 g of 1,4-butane sultone to a reactor containing 55 mL of acetonitrile solvent and stir to mix. Then, add 4 mL of a 3% sodium hydroxide solution dropwise. The mixture is reacted at 70°C for 4 h. After reaction, the solvent is removed by concentration under reduced pressure, washed, and dried to obtain a tertiary amino-modified sodium sulfonate.

[0071] S2. To the reactor were added 12.5 g of octamethylcyclotetrasiloxane, 1.2 g of 1,3-diglycidyloxypropyl-1,1,3,3-tetramethyldisiloxane, and 11 mg of tetramethylammonium hydroxide catalyst under nitrogen atmosphere. The reaction temperature was raised to 114 ° C for 5 h, then raised to 136 ° C for 1.2 h, the material was cooled, filtered and dried to obtain a double-ended epoxy silicone oil;

[0072] S3. To 50 mL of tetrahydrofuran solvent, 1 g of double-terminal epoxy silicone oil and 2.11 g of tertiary amino-modified sodium sulfonate were added, followed by the addition of 0.012 g of tetrabutylammonium bromide catalyst. The temperature was raised to 58°C and the quaternization reaction was carried out for 5 h. After completion, rotary distillation and silica gel column chromatography were performed to separate the mixture using a mixed solution of petroleum ether and ethyl acetate as the eluent, and gradient elution was performed to obtain hydroxyl-modified double-terminal sodium sulfonate;

[0073] S4. Add 3.1 g of glycolide, 1 g of ε-caprolactone, 0.13 g of hydroxyl-modified sodium double-ended sulfonate and 0.125 g of 1,4-butanediol into a three-necked flask containing 45 mL of chloroform, introduce nitrogen at 95°C for protection, stir for 22 minutes at a stirring rate of 300 r / min, raise the temperature to 190°C, and continue to add 0.01 g of stannous octoate catalyst, stir and react for 3 hours to obtain the product, which is then washed to obtain a quaternary ammonium salt-modified copolyester.

[0074] The preparation method of the extruded insulated low-voltage power cable is as follows:

[0075] Step 1: annealing the copper rod by drawing to obtain copper wire, and twisting multiple copper wires to form a copper wire core;

[0076] Step 2: Extruding the insulating material around the outer periphery of the copper wire core, and forming an insulating layer through cross-linking to obtain a cable; the specific steps are: adding the insulating material to the extruder hopper, and gradually plasticizing and melting the insulating material in the barrel through the rotation of the screw and the heating effect of the heating system. The temperature setting of the extruder is successively increased from the feeding section to the head section, which is 120, 150 ° C, and 180 ° C to ensure that the material is fully plasticized and has good fluidity. A mold is installed at the extruder head. The shape of the mold core and the mold sleeve in the mold matches the size and shape of the cable insulation layer. When the insulating material is melted, it is extruded through the annular gap between the mold core and the mold sleeve under a certain pressure, and tightly wrapped around the outside of the copper wire core to form an insulating layer.

[0077] Step 3: Wrap an inner lining layer around the outer surface of the cable, and then wrap an outer sheath around the outer periphery of the inner lining layer to obtain an extruded insulated low-voltage power cable.

[0078] The outer sheath is prepared by mixing polyvinyl chloride, quaternary ammonium salt modified copolyester, o-phenylphenol and talcum powder, kneading at 165° C. for 4 minutes, and forming the outer sheath.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 3 is that tertiary amine-modified sodium sulfonate is used instead of quaternary ammonium salt-modified copolyester.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 3 is that hydroxyl-modified double-terminated sodium sulfonate is used instead of quaternary ammonium salt-modified copolyester.

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 3 is that no quaternary ammonium salt is added to modify the copolyester.

[0085] The tensile strength and elongation at break of the outer sheath were measured with reference to GB / T 1040.1-2018. The limiting oxygen index of the outer sheath was measured with reference to ISO4589-2.

[0086] Table 1: Mechanical and flame retardancy tests.

[0087]

[0088]

[0089] As can be seen from Table 1, Examples 1-3 of the present invention have better tensile and flame retardant effects than Comparative Examples 1-3.

[0090] Antibacterial rate: tested according to the film-sticking method in accordance with test method 1 of GB 21551.2-2010. Test bacteria: Escherichia coli (ATCC 25922).

[0091] project Antibacterial rate (%) Example 1 99.9 Example 2 99.9 Example 3 99.9 Comparative Example 1 60.2 Comparative Example 2 93.5 Comparative Example 3 55.1

[0092] As can be seen from Table 1, Examples 1-3 of the present invention have better antibacterial effects than Comparative Examples 1-3.

[0093] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0095] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive examples. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. An extruded insulated low-voltage power cable, characterized in that: Includes the following weight components: copper wire core, insulation material, inner lining layer, outer sheath; The insulating material comprises the following components by weight: 80-100 parts by weight of low-density polyethylene and 1-3 parts by weight of nano-grade zinc oxide; The inner lining layer is made of polyvinyl chloride wrapping tape; The outer sheath comprises the following components by weight: 85-120 parts by weight of polyvinyl chloride, 8-15 parts by weight of quaternary ammonium salt modified copolyester, 10-16 parts by weight of o-phenylphenol, and 1-3 parts by weight of talc; The preparation method of the quaternary ammonium salt modified copolyester is: S1. Add N,N'-dimethylethylenediamine and 1,4-butane sultone to a reactor containing acetonitrile solvent, stir and mix, then add dropwise a 2-5% by mass sodium hydroxide solution, react at 65-80°C for 3-5 hours, and then concentrate under reduced pressure to remove the solvent, wash, and dry to obtain a tertiary amino-modified sodium sulfonate. S2. To the reactor were added 12.1-12.8 g of octamethylcyclotetrasiloxane, 1-1.5 g of 1,3-diglycidyloxypropyl-1,1,3,3-tetramethyldisiloxane, and under a nitrogen atmosphere, 11-12 mg of tetramethylammonium hydroxide catalyst was added, the temperature was raised to 110-115 ° C for 4-5 h, and then the temperature was raised to 135-140 ° C for 1-1.5 h, the material was cooled, filtered and dried to obtain a double-ended epoxy silicone oil; S3. Add double-terminal epoxy silicone oil and tertiary amino-modified sodium sulfonate to tetrahydrofuran solvent, then add tetrabutylammonium bromide catalyst, heat to 55-60 ° C, carry out quaternization reaction, and then rotary distillation and silica gel column chromatography separation, the eluent is a mixed solution of petroleum ether and ethyl acetate, gradient elution to obtain hydroxyl-modified double-terminal sodium sulfonate; S4. Add glycolide, ε-caprolactone, hydroxyl-modified double-ended sodium sulfonate and 1,4-butanediol to a three-necked flask filled with chloroform, introduce inert gas for protection at 90-100°C, stir for 20-25 minutes, raise the temperature to 180-200°C, continue to add stannous octoate catalyst, react for 2-4 hours to obtain the product, and then wash to obtain a quaternary ammonium salt-modified copolyester.

2. The extruded insulated low-voltage power cable according to claim 1, characterized in that: The usage ratio of N,N'-dimethylethylenediamine, 1,4-butanesultone, and sodium hydroxide solution in S1 is 1.13-1.26 g: 2.3-2.7 g: 3-6 mL.

3. The extruded insulated low-voltage power cable according to claim 1, characterized in that: The mass ratio of the double-ended epoxy silicone oil, tertiary amino-modified sodium sulfonate, and tetrabutylammonium bromide catalyst in S3 is 1g:1.85-2.14g:0.01-0.015g.

4. The extruded insulated low-voltage power cable according to claim 1, characterized in that: The reaction time in S3 is 4-6 hours.

5. The extruded insulated low-voltage power cable according to claim 1, characterized in that: The inert gas in S4 is nitrogen.

6. The extruded insulated low-voltage power cable according to claim 1, characterized in that: The mass ratio of glycolide, ε-caprolactone, hydroxyl-modified double-ended sodium sulfonate, 1,4-butanediol, and stannous octoate in S4 is 3.1-3.2g: 1g: 0.1-0.14g: 0.12-0.13g: 0.01-0.02g.

7. The extruded insulated low-voltage power cable according to claim 1, characterized in that: The stirring rate in S4 is 300-310 r / min.

8. A method for preparing an extruded insulated low-voltage power cable according to any one of claims 1 to 7, characterized in that: The preparation method of the extruded insulated low-voltage power cable is as follows: Step 1: The copper rod is drawn and annealed to obtain copper wire, and multiple copper wires are twisted to form a copper wire core; Step 2: Extruding the insulating material around the outer periphery of the copper wire core, and cross-linking the insulating material to form an insulating layer to obtain a cable; Step 3: Wrap an inner lining layer around the outer surface of the cable, and then wrap an outer sheath around the outer periphery of the inner lining layer to obtain an extruded insulated low-voltage power cable.

9. The method for preparing an extruded insulated low-voltage power cable according to claim 8, characterized in that: The outer sheath is prepared by mixing polyvinyl chloride, quaternary ammonium salt modified copolyester, o-phenylphenol and talcum powder, kneading at 160-170° C. for 3-5 minutes, and forming the outer sheath.

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