A high-voltage flame-retardant power cable and a method for producing the same

Abstract

The application relates to the technical field of cables, and discloses a high-voltage flame-retardant power cable and a preparation method thereof. The high-voltage flame-retardant power cable comprises, from inside to outside, a cable core, an insulation layer, a shielding layer and an outer sheath layer. The shielding layer comprises, from inside to outside, an insulation shielding layer and a metal shielding layer. The cable core comprises, from inside to outside, a conductor and a conductor shielding layer. The insulation layer is a cross-linked polyethylene insulation layer. The outer sheath layer comprises the following components in parts by weight: 55-65 parts of polyethylene, 35-45 parts of polyvinyl chloride, 3-6 parts of ethylene-vinyl alcohol copolymer, 4-8 parts of flame retardant PSPPP, 4-8 parts of flame retardant XDPO, 8-12 parts of a filler, 8-12 parts of a compatilizer, 1-1.5 parts of a heat stabilizer and 0.5-1 part of an antioxidant. The above technical scheme solves the problem of insufficient flame retardancy of high-voltage power cables in the related art.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a high-voltage flame-retardant power cable and its preparation method. Background Technology

[0002] High-voltage power cables, as core infrastructure equipment in power transmission systems, are widely used in power grid transmission, industrial support, rail transportation, and other technical fields. The outer sheath of the cable is a crucial protective structure that ensures the insulation structure of the high-voltage cable, resists external environmental corrosion, and prevents the spread of fire. Its flame-retardant properties are key indicators for curbing cable fires, preventing the spread of fire, and reducing losses during power cable replacement.

[0003] Currently, the flame-retardant modification technology for the outer sheath of high-voltage power cables in China generally suffers from a lack of simplistic formulation design. Most industry practitioners use a single inorganic or organic flame retardant to modify the outer sheath, resulting in a simple and limited formulation structure. This traditional modification method offers limited improvement in flame-retardant performance and is ill-suited to the safety requirements of high-voltage cables under complex operating conditions. The overall flame-retardant performance exhibits significant defects: single flame retardant systems have low flame-retardant efficiency; under long-term high-voltage current carrying, alternating temperature rises, and short-circuit overload conditions, the outer sheath is prone to carbonization, cracking, and molten dripping, failing to effectively prevent the spread of open flames and heat transfer; furthermore, the flame-retardant effect of a single component is limited, easily generating toxic fumes when the cable encounters fire, and molten drippings can trigger secondary combustion and explosion accidents.

[0004] Therefore, the aforementioned problems restrict the safe and stable operation of high-voltage power cables in scenarios requiring flame retardant performance, such as power grid hubs, industrial plants, and rail transit. It is necessary to develop high-voltage power cables with excellent flame retardant performance. Summary of the Invention

[0005] This invention proposes a high-voltage flame-retardant power cable and its preparation method to solve or alleviate at least one of the above-mentioned problems.

[0006] The technical solution of the present invention is as follows: This invention proposes a high-voltage flame-retardant power cable, comprising, from the inside out, a cable core, an insulation layer, a shielding layer, and an outer sheath layer; the shielding layer comprises, from the inside out, an insulating shielding layer and a metallic shielding layer; the cable core comprises, from the inside out, a conductor and a conductor shielding layer; the insulation layer is a cross-linked polyethylene insulation layer; the outer sheath layer comprises the following components in parts by weight: 55-65 parts polyethylene, 35-45 parts polyvinyl chloride, 3-6 parts ethylene-vinyl alcohol copolymer, 4-9 parts flame retardant PSPPP, 4-8 parts flame retardant XDPO, 8-12 parts filler, 8-12 parts compatibilizer, 1-1.5 parts heat stabilizer, and 0.5-1 part antioxidant.

[0007] Preferably, the mass ratio of the flame retardant PSPPP to the flame retardant XDPO is 6:4.

[0008] Preferably, the outer sheath layer comprises the following components in parts by weight: 55-65 parts polyethylene, 35-45 parts polyvinyl chloride, 3-6 parts ethylene-vinyl alcohol copolymer, 6 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 4-6 parts zinc stannate, 8-12 parts filler, 8-12 parts compatibilizer, 1-1.5 parts heat stabilizer, and 0.5-1 part antioxidant.

[0009] Preferably, the mass ratio of the flame retardant PSPPP, the flame retardant XDPO, and zinc stannate is 6:4:5.

[0010] Preferably, the filler comprises inorganic powder and / or fiber filler; the inorganic powder comprises at least one of calcium carbonate, talc, carbon black and mica powder; The fiber filler includes at least one of glass fiber, carbon fiber and aramid fiber.

[0011] Preferably, the compatibilizer includes at least one of maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene.

[0012] Preferably, the heat stabilizer includes at least one of stearate and calcium-zinc stabilizer.

[0013] Preferably, the antioxidant is a composite antioxidant, including phenolic antioxidants and phosphite antioxidants.

[0014] Preferably, the mass ratio of the phenolic antioxidant to the phosphite antioxidant is 5:1 to 3.

[0015] This invention also proposes a method for preparing a high-voltage flame-retardant power cable, comprising the following steps: After a single mixing of polyethylene, polyvinyl chloride, ethylene-vinyl alcohol copolymer, compatibilizer, heat stabilizer and antioxidant, the remaining components of the outer sheath layer are added and mixed to obtain the mixture for the outer sheath layer. An insulation layer and a shielding layer are sequentially arranged on the outside of the cable core. The outer sheath layer is then extruded with a mixture to cover the shielding layer, thus obtaining the high-voltage flame-retardant power cable.

[0016] The beneficial effects of this invention are as follows: In this invention, two flame retardants, PSPPP and XDPO, are compounded and added to the outer sheath layer of high-voltage power cables. This effectively solves the technical defects of insufficient flame retardant performance in traditional single flame retardant systems and significantly improves the flame retardancy of high-voltage power cables. Among them, the flame retardant PSPPP (polyphenylphosphonic acid diphenyl sulfone ester) can promote the dehydration and cross-linking of the outer sheath layer substrate at high temperatures, and form dense char, exerting a condensed phase flame retardant mechanism to form a stable and dense char layer structure. This effectively blocks the inward conduction of external oxygen and heat, inhibiting the thermal decomposition of the substrate. At the same time, the flame retardant XDPO (p-xylylbis(diphenylphosphine oxide)) can exert a gas-phase flame retardant effect. After thermal decomposition, it can capture combustion free radicals, dilute the concentration of combustible gases, and block the combustion chain reaction. The combined use of the two flame retardants can achieve synergistic flame retardancy in both the condensed and gas phases, avoiding the problem of limited flame retardancy and efficiency of a single flame retardant. Both are organic flame retardants with good compatibility with the polymer matrix and can be stably dispersed in the outer sheath substrate, improving flame retardant performance while retaining the excellent mechanical properties of the outer sheath. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be described through embodiments.

[0019] A specific embodiment of the first aspect of the present invention provides a high-voltage flame-retardant power cable, comprising, from the inside out, a cable core, an insulation layer, a shielding layer, and an outer sheath layer. The shielding layer comprises, from the inside out, an insulating shielding layer and a metallic shielding layer. The cable core comprises, from the inside out, a conductor and a conductor shielding layer. The insulation layer is a cross-linked polyethylene insulation layer. The outer sheath layer comprises the following components in parts by weight: 55-65 parts of polyethylene, 35-45 parts of polyvinyl chloride, 3-6 parts of ethylene-vinyl alcohol copolymer, 4-9 parts of flame retardant PSPPP, 4-8 parts of flame retardant XDPO, 8-12 parts of filler, 8-12 parts of compatibilizer, 1-1.5 parts of heat stabilizer, and 0.5-1 part of antioxidant.

[0020] In this invention, the flame retardant for the outer sheath of the high-voltage flame-retardant power cable is composed of flame retardant PSPPP and flame retardant XDPO. The amount of flame retardant PSPPP added is 4 to 9 parts, for example, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.4 parts, 9 parts, etc.; the amount of flame retardant XDPO added is 4 to 8 parts, for example, 4 parts, 4.2 parts, 4.6 parts, 5 parts, 5.4 parts, 5.8 parts, 6.2 parts, 6.6 parts, 7 parts, 7.4 parts, 7.8 parts, 8 parts, etc. Based on this, when the mass ratio of flame retardant PSPPP to flame retardant XDPO is 6:4, the synergistic flame retardant effect of flame retardant PSPPP and flame retardant XDPO is better, which can further improve the flame retardancy.

[0021] In one embodiment of the present invention, the outer sheath layer comprises the following components in parts by weight: 55-65 parts of polyethylene, 35-45 parts of polyvinyl chloride, 3-6 parts of ethylene-vinyl alcohol copolymer, 6 parts of flame retardant PSPPP, 4 parts of flame retardant XDPO, 4-6 parts of zinc stannate, 8-12 parts of filler, 8-12 parts of compatibilizer, 1-1.5 parts of heat stabilizer, and 0.5-1 part of antioxidant.

[0022] In this invention, zinc stannate is further introduced into the flame retardant system of flame retardants PSPPP and XDPO as a flame retardant synergist. It possesses smoke-suppressing, anti-dripping, and char-aiding properties, which help improve the density and thermal stability of the char layer, preventing cracking and peeling, thus further enhancing the flame retardant effect. Furthermore, the advantage of this invention lies in the use of specific flame retardants PSPPP, XDPO, and zinc stannate. If any one of these flame retardants is missing... Replacing one or more flame retardants with a combination of conventional flame retardants in the field will reduce the flame retardant effect. The amount of zinc stannate added is 4 to 6 parts, for example, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 parts, 5.2 parts, 5.5 parts, 5.8 parts, 6 parts, etc. When the mass ratio of flame retardant PSPPP, flame retardant XDPO and zinc stannate is 6:4:5, the flame retardant effect of PSPPP, flame retardant XDPO and zinc stannate is optimal.

[0023] In this invention, the filler for the outer sheath of the high-voltage flame-retardant power cable includes inorganic powder and / or fiber filler. The inorganic powder includes at least one of calcium carbonate, talc, carbon black, and mica powder, which enhances the hardness, wear resistance, and chemical corrosion resistance of the outer sheath. The fiber filler includes at least one of glass fiber, carbon fiber, and aramid fiber, with a diameter of 5-10 μm (e.g., 5 μm, 6 μm, 8 μm, 10 μm) and a length of 0.05-5 mm (e.g., 0.05 mm, 0.5 mm, 1 mm, 3 mm, 5 mm). Due to its high strength and high modulus, the fiber filler significantly improves the mechanical strength of the outer sheath, enhancing its tensile and bending resistance.

[0024] In this invention, the compatibilizer for the outer sheath of the high-voltage flame-retardant power cable includes at least one of maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene. The compatibilizer effectively improves the compatibility between the components and enhances interfacial bonding, thereby ensuring the overall performance of the outer sheath and guaranteeing the stable operation of the high-voltage power cable in various environments.

[0025] In this invention, the heat stabilizer for the outer sheath of the high-voltage flame-retardant power cable effectively inhibits the degradation reaction of polyvinyl chloride during processing, extending the service life of the outer sheath. The heat stabilizer includes at least one of stearate and calcium-zinc stabilizers. For example, stearate can be lead stearate, barium stearate, calcium stearate, etc.

[0026] In this invention, the anti-aging agent for the outer sheath of the high-voltage flame-retardant power cable is a composite anti-aging agent, composed of phenolic anti-aging agents and phosphite anti-aging agents. It can effectively inhibit the aging phenomenon caused by oxidation, heat and other factors during long-term use of the cable. The phenolic anti-aging agent can be, for example, anti-aging agent 264, anti-aging agent 2246, etc.; the phosphite anti-aging agent can be, for example, anti-aging agent 168, anti-aging agent 619, etc.; the mass ratio of phenolic anti-aging agent to phosphite anti-aging agent is 5:1~3, for example, 5:1, 5:1.5, 5:2, 5:2.5, 5:3, etc.

[0027] A second aspect of the present invention provides a method for preparing a high-voltage flame-retardant power cable, used to prepare the high-voltage flame-retardant power cable provided in the first aspect of the present invention, comprising the following steps: After a single mixing of polyethylene, polyvinyl chloride, ethylene-vinyl alcohol copolymer, compatibilizer, heat stabilizer and antioxidant, the remaining components of the outer sheath layer are added and mixed to obtain the mixture for the outer sheath layer. An insulation layer and a shielding layer are sequentially installed on the outside of the cable core. The outer sheath layer is then extruded with a mixture to cover the shielding layer, resulting in a high-voltage flame-retardant power cable.

[0028] The present invention will now be described in detail with reference to preferred embodiments and comparative examples. The preferred embodiments of the present invention described below can be modified in various ways, and therefore the scope of the invention should not be construed as limited to the preferred embodiments described in detail below. Preferred embodiments are provided to help those skilled in the art to more readily understand the present invention.

[0029] In the following examples and comparative examples, the polyethylene type is 5301AA; The polyvinyl chloride (PVC) model number is DG-1300; The model number of the ethylene-vinyl alcohol copolymer is DT2904R; The model number of maleic anhydride-grafted polyethylene is TY1053H. The average particle size of zinc stannate is 3.8 μm; The calcium-zinc stabilizer is model MC 9700 KA / 1; The average particle size of talc is 5 μm; The glass fiber has an average diameter of 8μm and a length of 2mm.

[0030] Example 1 The high-voltage flame-retardant power cable comprises, from the inside out, a cable core, an insulation layer, a shielding layer, and an outer sheath. The shielding layer comprises, from the inside out, an insulating shielding layer and a metallic shielding layer. The cable core comprises, from the inside out, a conductor and a conductor shielding layer. The insulation layer is a cross-linked polyethylene insulation layer. The outer sheath comprises the following components in parts by weight: 55 parts polyethylene, 45 parts polyvinyl chloride, 3 parts ethylene-vinyl alcohol copolymer, 4 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 4 parts talc, 4 parts glass fiber, 8 parts maleic anhydride-grafted polyethylene, 1 part calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168. A method for preparing high-voltage flame-retardant power cables includes the following steps: After a single mixing of polyethylene, polyvinyl chloride, ethylene-vinyl alcohol copolymer, maleic anhydride-grafted polyethylene, calcium zinc stabilizer and antioxidant 2246, antioxidant 168, the remaining components of the outer sheath layer are added and mixed to obtain the mixture for the outer sheath layer. An insulation layer and a shielding layer are sequentially installed on the outside of the cable core. The outer sheath layer is then extruded with a mixture to cover the shielding layer, resulting in a high-voltage flame-retardant power cable.

[0031] Example 2 The high-voltage flame-retardant power cable comprises, from the inside out, a cable core, an insulation layer, a shielding layer, and an outer sheath. The shielding layer comprises, from the inside out, an insulating shielding layer and a metallic shielding layer. The cable core comprises, from the inside out, a conductor and a conductor shielding layer. The insulation layer is a cross-linked polyethylene insulation layer. The outer sheath comprises the following components in parts by weight: 65 parts polyethylene, 35 parts polyvinyl chloride, 6 parts ethylene-vinyl alcohol copolymer, 8 parts flame retardant PSPPP, 8 parts flame retardant XDPO, 6 parts talc, 6 parts glass fiber, 12 parts maleic anhydride-grafted polyethylene, 1.5 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168. A method for preparing high-voltage flame-retardant power cables includes the following steps: After a single mixing of polyethylene, polyvinyl chloride, ethylene-vinyl alcohol copolymer, maleic anhydride-grafted polyethylene, calcium zinc stabilizer and antioxidant 2246, antioxidant 168, the remaining components of the outer sheath layer are added and mixed to obtain the mixture for the outer sheath layer. An insulation layer and a shielding layer are sequentially installed on the outside of the cable core. The outer sheath layer is then extruded with a mixture to cover the shielding layer, resulting in a high-voltage flame-retardant power cable.

[0032] Example 3 The high-voltage flame-retardant power cable comprises, from the inside out, a cable core, an insulation layer, a shielding layer, and an outer sheath. The shielding layer comprises, from the inside out, an insulating shielding layer and a metallic shielding layer. The cable core comprises, from the inside out, a conductor and a conductor shielding layer. The insulation layer is a cross-linked polyethylene insulation layer. The outer sheath comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 4 parts flame retardant PSPPP, 6 parts flame retardant XDPO, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168. A method for preparing high-voltage flame-retardant power cables includes the following steps: After a single mixing of polyethylene, polyvinyl chloride, ethylene-vinyl alcohol copolymer, maleic anhydride-grafted polyethylene, calcium zinc stabilizer and antioxidant 2246, antioxidant 168, the remaining components of the outer sheath layer are added and mixed to obtain the mixture for the outer sheath layer. An insulation layer and a shielding layer are sequentially installed on the outside of the cable core. The outer sheath layer is then extruded with a mixture to cover the shielding layer, resulting in a high-voltage flame-retardant power cable.

[0033] Example 4 The outer sheath layer of this embodiment comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 6 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride grafted polyethylene, 1.2 parts calcium zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0034] Example 5 The outer sheath layer of this embodiment comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 7 parts flame retardant PSPPP, 3 parts flame retardant XDPO, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride grafted polyethylene, 1.2 parts calcium zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0035] Example 6 The outer sheath layer of this embodiment comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 6 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 4 parts zinc stannate, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0036] Example 7 The outer sheath layer of this embodiment comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 6 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 5 parts zinc stannate, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0037] Example 8 The outer sheath layer of this embodiment comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 6 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 6 parts zinc stannate, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0038] Example 9 The outer sheath layer of this embodiment comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 8.4 parts flame retardant PSPPP, 5.6 parts flame retardant XDPO, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride grafted polyethylene, 1.2 parts calcium zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0039] Comparative Example 1 This comparative exception sheath layer comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 10 parts flame retardant PSPPP, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0040] Comparative Example 2 This comparative exception sheath layer comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 10 parts flame retardant XDPO, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0041] Comparative Example 3 This comparative exception sheath layer comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 8.4 parts flame retardant PSPPP, 5.6 parts zinc stannate, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0042] Comparative Example 4 This comparative exception sheath layer comprises the following components in parts by weight: 60 parts polyethylene, 40 parts polyvinyl chloride, 5 parts ethylene-vinyl alcohol copolymer, 7 parts flame retardant XDPO, 7 parts zinc stannate, 5 parts talc, 5 parts glass fiber, 10 parts maleic anhydride-grafted polyethylene, 1.2 parts calcium-zinc stabilizer, 0.5 parts antioxidant 2246, and 0.5 parts antioxidant 168; The rest is the same as in Example 3.

[0043] The following performance tests were conducted on the outer sheath of the high-voltage flame-retardant power cables of Examples 1-9 and Comparative Examples 1-4: The oxygen index was tested according to Method A - Top Surface Ignition Method in standard GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test" to characterize flame retardant performance (the sample shape is I-shaped, with dimensions of 120mm × 10mm × 4mm). The notched impact strength of the cantilever beam was determined according to the standard GB / T 1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams" (notch type A). The test results are shown in Table 1 below.

[0044] Table 1 Performance Test Results

[0045] As can be seen from the performance test results in Table 1, the high-voltage flame-retardant power cable outer sheath prepared in each embodiment of the present invention has significantly better flame-retardant performance than the comparative sample. The oxygen index of Examples 1-9 remained above 37.2%, reaching a maximum of 44.7%, significantly higher than the 29.8%-35.1% of Comparative Examples 1-4, demonstrating a significant improvement in flame retardant performance. Comparative Examples 1 and 2, using only single flame retardants PSPPP or XDPO, had oxygen indices of only 32.5% and 29.8%, respectively. Examples 1-5, using a combination of PSPPP and XDPO, all achieved oxygen indices above 37.2%, with Example 4 (6:4 mass ratio) reaching an oxygen index of 39.6%, demonstrating the synergistic flame retardant effect of the dual flame retardant system. Examples 6-8, further introducing zinc stannate as a flame retardant synergist, further increased the oxygen index to above 41.9%. Example 7, with a PSPPP, XDPO, and zinc stannate mass ratio of 6:4:5, reached a peak oxygen index of 43.7%, fully illustrating that the introduction of zinc stannate can further enhance the flame retardant effect of the dual flame retardant system.

[0046] In addition, compared with Comparative Examples 3-4 and Example 4, Examples 6-8, which contain flame retardant PSPPP, flame retardant XDPO and zinc stannate, also have higher notched impact strength, indicating that the combined use of flame retardant PSPPP, flame retardant XDPO and zinc stannate improves impact strength.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-voltage flame-retardant power cable, characterized in that, The cable comprises, from the inside out, a cable core, an insulation layer, a shielding layer, and an outer sheath. The shielding layer comprises, from the inside out, an insulating shielding layer and a metallic shielding layer. The cable core comprises, from the inside out, a conductor and a conductor shielding layer. The insulation layer is a cross-linked polyethylene insulation layer. The outer sheath comprises the following components in parts by weight: 55-65 parts polyethylene, 35-45 parts polyvinyl chloride, 3-6 parts ethylene-vinyl alcohol copolymer, 4-9 parts flame retardant PSPPP, 4-8 parts flame retardant XDPO, 8-12 parts filler, 8-12 parts compatibilizer, 1-1.5 parts heat stabilizer, and 0.5-1 part antioxidant.

2. The high-voltage flame-retardant power cable according to claim 1, characterized in that, The mass ratio of the flame retardant PSPPP to the flame retardant XDPO is 6:

4.

3. The high-voltage flame-retardant power cable according to claim 2, characterized in that, The outer sheath layer comprises the following components in parts by weight: 55-65 parts polyethylene, 35-45 parts polyvinyl chloride, 3-6 parts ethylene-vinyl alcohol copolymer, 6 parts flame retardant PSPPP, 4 parts flame retardant XDPO, 4-6 parts zinc stannate, 8-12 parts filler, 8-12 parts compatibilizer, 1-1.5 parts heat stabilizer, and 0.5-1 part antioxidant.

4. The high-voltage flame-retardant power cable according to claim 3, characterized in that, The mass ratio of the flame retardant PSPPP, the flame retardant XDPO, and the zinc stannate is 6:4:

5.

5. The high-voltage flame-retardant power cable according to any one of claims 1 to 4, characterized in that, The filler includes inorganic powder and / or fiber filler; the inorganic powder includes at least one of calcium carbonate, talc, carbon black and mica powder; The fiber filler includes at least one of glass fiber, carbon fiber and aramid fiber.

6. The high-voltage flame-retardant power cable according to any one of claims 1 to 4, characterized in that, The compatibilizer includes at least one of maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene.

7. The high-voltage flame-retardant power cable according to any one of claims 1 to 4, characterized in that, The heat stabilizer includes at least one of stearate and calcium-zinc stabilizer.

8. The high-voltage flame-retardant power cable according to any one of claims 1 to 4, characterized in that, The antioxidant is a composite antioxidant, including phenolic antioxidants and phosphite antioxidants.

9. The high-voltage flame-retardant power cable according to claim 8, characterized in that, The mass ratio of the phenolic antioxidant to the phosphite antioxidant is 5:1~3.

10. A method for preparing a high-voltage flame-retardant power cable, used to prepare the high-voltage flame-retardant power cable according to any one of claims 1 to 9, characterized in that, Includes the following steps: After a one-time mixing of polyethylene, polyvinyl chloride, ethylene-vinyl alcohol copolymer, compatibilizer, heat stabilizer and antioxidant, the remaining components of the outer sheath layer are added and mixed to obtain the mixture for the outer sheath layer. An insulation layer and a shielding layer are sequentially arranged on the outside of the cable core. The outer sheath layer is then extruded with a mixture to cover the shielding layer, thus obtaining the high-voltage flame-retardant power cable.

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