Environment-friendly fire-resistant power cable and preparation method thereof

Abstract

The invention relates to the field of cables, and provides an environment-friendly fire-resistant power cable aiming at the problems of high cost and insufficient flame retardant property of a fire-resistant cable in the prior art, the environment-friendly fire-resistant power cable comprises a plurality of stranded copper conductors, a fire-resistant layer and an insulating layer, and the fire-resistant layer and the insulating layer are sequentially coated outside the stranded copper conductors; the fireproof layer is a mica tape, and the insulating layer is prepared from, by weight, 15-25 parts of ethylene-vinyl acetate copolymer, 10-15 parts of polyethylene, 10-15 parts of maleic anhydride, 15-25 parts of ceramic powder, 3-7 parts of kaolin, 20-30 parts of aluminum hydroxide, 15-25 parts of magnesium hydroxide, 1-3 parts of antioxidant and 0.5-3 parts of cross-linking agent. The material and the structure of the cable are optimized, so that the cable has excellent fire-resistant and flame-retardant properties.

Description

Technical Field

[0001] This invention relates to the field of cables, and in particular to an environmentally friendly fire-resistant power cable and its preparation method. Background Technology

[0002] Unlike flame-retardant cables, which focus on preventing the rapid spread of fire, fire-resistant cables ensure that the circuit can maintain normal power supply and transmit various control and alarm signals for a certain period of time during a fire, providing valuable time for evacuation and rescue. The BS6387 fire-resistant standard is being gradually adopted, requiring fire-resistant cables to have high-temperature resistance, maintain stable power transmission at high temperatures, and produce relatively little smoke when burning.

[0003] Chinese patent application CN201510852720.5 discloses a halogen-free flame-retardant ceramicized polyolefin cable material for fire-resistant cables and its preparation method. Upon ignition at high temperatures, the material undergoes ceramicization, transforming into a hard ceramic protective layer with certain mechanical strength, ensuring the normal operation of the wire and cable lines. However, microcapsules are costly and difficult to popularize, and they are easily destroyed upon ignition at high temperatures, affecting the release of red phosphorus and resulting in poor flame-retardant performance. Summary of the Invention

[0004] In order to overcome the problems of high cost and insufficient flame retardant performance of existing fire-resistant cables, this invention provides an environmentally friendly fire-resistant power cable. Through optimization of materials and structure, it has excellent flame retardant performance and reduces costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an environmentally friendly fire-resistant power cable, comprising a multi-strand stranded copper conductor, a fire-resistant layer, and an insulation layer, wherein the stranded copper conductor is sequentially covered with the fire-resistant layer and the insulation layer; the fire-resistant layer is mica tape, wherein the raw materials of the insulation layer include the following components in parts by weight: 15-25 parts of ethylene-vinyl acetate copolymer, 10-15 parts of polyethylene, 10-15 parts of maleic anhydride, 15-25 parts of ceramic powder, 3-7 parts of kaolin, 20-30 parts of aluminum hydroxide, 15-25 parts of magnesium hydroxide, 1-3 parts of antioxidant, and 0.5-3 parts of crosslinking agent.

[0006] Mica possesses extremely high heat resistance and low thermal conductivity. Environmentally friendly fire-resistant power cables utilize mica tape as the fire-resistant layer. This allows the mica tape to slow heat conduction in the event of a fire, effectively protecting the cable conductors, maintaining their structure and electrical performance, and ensuring a longer period of safe operation. Furthermore, mica is a natural mineral, renewable, and free of toxic chemicals, meeting environmental protection standards. In fire or high-temperature conditions, mica does not release harmful gases, reducing harm to the environment and human health. Mica itself has excellent insulation properties, effectively preventing short circuits and leaks in cables at high temperatures, improving cable safety. Mica tape is relatively lightweight, facilitating handling during cable production and installation without adding excessive burden.

[0007] The insulation layer prepared from the above raw materials is a halogen-free polyolefin. It releases no halogen acid gas during combustion, with minimal release of toxic and corrosive gases, resulting in extremely low smoke concentration and excellent flame-retardant properties. In the insulation layer of environmentally friendly fire-resistant power cables, various raw materials play different roles, as follows: Ceramic powder is added as a raw material, which, upon ignition at high temperatures, undergoes vitrification to transform into a hard ceramic protective layer, providing excellent heat insulation and a certain mechanical strength, ensuring the normal operation of the cable line. The various raw materials in the insulation layer play different roles, as follows: Maleic anhydride, as a copolymer modifier, helps enhance the compatibility of polyethylene and ethylene-vinyl acetate copolymer, improving the interfacial bonding performance between the two relatively incompatible polymers. Therefore, the insulation material provides good electrical insulation properties, suitable for extreme environments, and improves the cable's toughness, heat resistance, and weather resistance. Ceramic powder and kaolin, as fillers, enhance the rigidity and strength of the material, improving high-temperature resistance. Aluminum hydroxide and magnesium hydroxide, as flame retardants, improve stability at high temperatures and cable safety, delaying flame propagation and inhibiting flame and smoke generation.

[0008] Preferably, the method for preparing the mica tape includes the following steps: (S1) Acidification treatment is performed on calcined mica paper to obtain calcined mica paper with carboxyl groups; (S2) Spray a water-based adhesive solution containing glass fibers onto the surface of calcined mica paper with carboxyl groups; (S3) Hot pressing, cooling and then winding and cutting to obtain a mica tape with mica on one side and glass fiber on the other side.

[0009] The layered structure of calcined mica allows it to form a seamless carbonized layer at high temperatures. This layer effectively isolates the flame and heat transfer, preventing the diffusion of heat and oxygen, thus significantly improving the material's flame retardant properties. The coating of glass fiber provides additional strength and thermal stability. Under high-temperature conditions, glass fiber not only increases structural integrity but also helps form a heat-resistant structure, preventing direct flame contact. Acidification of the calcined mica paper surface allows the acid to react with the silicon-oxygen and aluminum-oxygen chains on the mica powder surface, leading to the introduction of carboxyl groups (-COOH). In this process, the acid's reactivity allows it to break existing chemical bonds, promoting the formation of carboxyl groups. The introduction of carboxyl groups enhances its adhesion to glass fiber. The combination of calcined mica paper and glass fiber utilizes their respective advantages: calcined mica provides excellent flame retardancy and heat insulation, while glass fiber provides good mechanical strength and heat resistance, complementing each other to form a more effective flame-retardant barrier.

[0010] More preferably, the glass fiber is a modified glass fiber, and the preparation method of the modified glass fiber includes the following steps: placing the glass fiber in a hydrogen peroxide solution.

[0011] Hydrogen peroxide can corrode the surface of glass fibers, increasing their specific surface area and the number of active sites, thus promoting their dispersion on mica paper. Furthermore, hydrogen peroxide can introduce polar functional groups onto the glass fiber surface, improving the compatibility between the glass fibers and the insulating layer.

[0012] More preferably, the water-based adhesive is a polyurethane water-based adhesive.

[0013] Waterborne polyurethane adhesives exhibit excellent bonding strength, effectively bonding mica paper and glass fiber. After curing, waterborne polyurethane adhesives typically retain some elasticity, helping them adapt to temperature changes and the thermal expansion of materials, enabling applications in high-temperature environments.

[0014] Furthermore, the preparation method of the polyurethane waterborne adhesive includes the following steps: slowly stirring polyurethane acrylate with deionized water to avoid the formation of bubbles, while adding thickener and lubricant, and obtaining the polyurethane waterborne adhesive after defoaming.

[0015] Preferably, the thickness of the refractory layer is 0.12 to 0.16 mm; the refractory layer includes two layers of mica tape, which are composed of a first mica tape and a second mica tape wrapped around each other, and the stranded copper conductor is wrapped with the first mica tape and the second mica tape in sequence, with an overlap rate of 25% to 30%.

[0016] The tower-type mica uninterrupted wrapping machine is adopted. The tower-type mica has no joints in the middle. The middle part of the outer wrapping tape overlaps with the edge of the inner overlap. The equipment display screen can automatically set the overlap, and the wrapping is uniform and flat, which effectively ensures the wrapping quality and avoids failure of fire resistance test due to wrapping defects.

[0017] Preferably, the mica side of the mica tape is close to the stranded copper conductor, and the glass fiber side of the mica tape is close to the insulating layer.

[0018] The above technical solution features the mica layer facing inwards and the fiberglass layer facing outwards to effectively protect the mica layer from falling off.

[0019] Preferably, the thickness of the insulating layer is 2.4 to 2.6 mm.

[0020] Preferably, the conductor is a Class II tin-plated copper conductor, and more preferably a seven-strand stranded wire.

[0021] Secondly, the present invention provides a method for preparing an environmentally friendly fire-resistant power cable, comprising the following steps: (1) Preparation of multi-strand stranded copper conductor; (2) Wrap mica tape around the conductor to form a fire-resistant layer; (3) An insulation layer of 2.4-2.6 mm is extruded on the outside of the mica tape and cross-linked by irradiation to obtain an environmentally friendly fire-resistant power cable.

[0022] Therefore, the beneficial effects of the present invention are as follows: (1) Improve the fire resistance and flame retardancy of the cable by selecting materials for each layer of the cable material. For example, the insulation layer is selected as halogen-free polyolefin and polyurethane water-based adhesive, which has excellent flame retardancy and fire resistance. Mica tape is selected as the fire-resistant layer. In the event of a fire, the mica tape can delay heat conduction, effectively protect the conductor of the cable, maintain its structure and electrical performance, and maintain a safe working state for a longer period of time.

[0023] (2) By optimizing the preparation method of mica tape, the fire resistance of the cable is made better. For example, the calcined mica paper is acidified; hydrogen peroxide can corrode the surface of glass fiber; polyurethane water-based adhesive is used to bond mica paper and glass fiber, which can be used in high temperature environment. Detailed Implementation

[0024] The technical solution of the present invention will be further described below through specific embodiments.

[0025] In this invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the field. The methods in the embodiments, unless otherwise specified, are conventional methods in the field.

[0026] General Implementation Examples An environmentally friendly fire-resistant power cable includes a multi-strand stranded copper conductor, a fire-resistant layer, and an insulation layer. The stranded copper conductor is sequentially covered with the fire-resistant layer and the insulation layer. The fire-resistant layer is mica tape. The insulation layer is made of the following components in parts by weight: 15-25 parts ethylene-vinyl acetate copolymer, 10-15 parts polyethylene, 10-15 parts maleic anhydride, 15-25 parts ceramic powder, 3-7 parts kaolin, 20-30 parts aluminum hydroxide, 15-25 parts magnesium hydroxide, 1-3 parts antioxidant, and 0.5-3 parts crosslinking agent.

[0027] Preferably, the method for preparing the mica tape includes the following steps: (S1) Acidification treatment is performed on calcined mica paper to obtain calcined mica paper with carboxyl groups; (S2) Spray a water-based adhesive solution containing glass fibers onto the surface of calcined mica paper with carboxyl groups; (S3) Hot pressing, cooling and then winding and cutting to obtain a mica tape with mica on one side and glass fiber on the other side.

[0028] More preferably, the glass fiber is a modified glass fiber, and the preparation method of the modified glass fiber includes the following steps: placing the glass fiber in a hydrogen peroxide solution.

[0029] More preferably, the water-based adhesive is a polyurethane water-based adhesive.

[0030] Furthermore, the preparation method of the polyurethane waterborne adhesive includes the following steps: slowly stirring polyurethane acrylate with deionized water to avoid the formation of bubbles, while adding thickener and lubricant, and obtaining the polyurethane waterborne adhesive after defoaming.

[0031] Preferably, the thickness of the refractory layer is 0.12 to 0.16 mm; the refractory layer includes two layers of mica tape, which are composed of a first mica tape and a second mica tape wrapped around each other, and the stranded copper conductor is wrapped with the first mica tape and the second mica tape in sequence, with an overlap rate of 25% to 30%.

[0032] Preferably, the mica side of the mica tape is close to the stranded copper conductor, and the glass fiber side of the mica tape is close to the insulating layer.

[0033] Preferably, the thickness of the insulating layer is 2.4 to 2.6 mm.

[0034] Preferably, the conductor is a Class II tin-plated copper conductor, and more preferably a seven-strand stranded wire.

[0035] A method for preparing an environmentally friendly fire-resistant power cable includes the following steps: (1) Preparation of multi-strand stranded copper conductor; (2) Wrap mica tape around the conductor to form a fire-resistant layer; (3) An insulation layer of 2.4-2.6 mm is extruded on the outside of the mica tape and cross-linked by irradiation to obtain an environmentally friendly fire-resistant power cable.

[0036] Example 1 An environmentally friendly fire-resistant power cable is manufactured using the following steps: (1) Prepare 7 strands of type II tin-plated copper conductor; (2) Preparation of refractory layer: S1: Acidification treatment is performed on calcined mica paper to obtain calcined mica paper with carboxyl groups; S2: Place glass fibers in a hydrogen peroxide solution to modify them; slowly stir polyurethane acrylate with deionized water to avoid forming bubbles, while adding thickener polyvinyl alcohol and lubricant silicone oil, and let the mixture stand for 60 minutes to allow the bubbles to dissipate, thus obtaining a water-based polyurethane adhesive; add the modified glass fibers to the water-based polyurethane adhesive, and spray the water-based polyurethane adhesive solution containing the modified glass fibers onto the surface of calcined mica paper with carboxyl groups, and then dry it; S3: Hot pressing, cooling, and then winding and slitting to obtain mica tape; S4: Two layers of mica tape are wrapped around the conductor. The mica side of the mica tape is close to the stranded copper conductor, and the glass fiber side of the mica tape is close to the insulation layer. The overlap rate is 30%, forming a fire-resistant layer with a thickness of 0.16mm. (3) Preparation of the insulating layer: SS1: Preparation of insulating layer particles: EVA ethylene-vinyl acetate copolymer, polyethylene mLLDPE, maleic anhydride, ceramic powder, kaolin, aluminum hydroxide, magnesium hydroxide, antioxidant DLTP and crosslinking agent TAIC are mixed according to the components shown in Table 1 by weight. After mixing and plasticizing, the mixture is extruded and granulated to obtain insulating layer particles. SS2: An insulation layer of 2.6mm is extruded onto the outside of mica tape and cross-linked by irradiation to obtain an environmentally friendly fire-resistant power cable.

[0037] Example 2 An environmentally friendly fire-resistant power cable is manufactured using the following steps: (1) Prepare 7 strands of type II tin-plated copper conductor; (2) Preparation of refractory layer: S1: Acidification treatment is performed on calcined mica paper to obtain calcined mica paper with carboxyl groups; S2: Place glass fibers in a hydrogen peroxide solution to modify them; slowly stir polyurethane acrylate with deionized water to avoid forming bubbles, while adding thickener polyvinyl alcohol and lubricant silicone oil, and let the mixture stand for 60 minutes to allow the bubbles to dissipate, thus obtaining a water-based polyurethane adhesive; add the modified glass fibers to the water-based polyurethane adhesive, and spray the water-based polyurethane adhesive solution containing the modified glass fibers onto the surface of calcined mica paper with carboxyl groups, and then dry it; S3: Hot pressing, cooling, and then winding and slitting to obtain mica tape; S4: Two layers of mica tape are wrapped around the conductor. The mica side of the mica tape is close to the stranded copper conductor, and the glass fiber side of the mica tape is close to the insulation layer. The overlap rate is 25%, forming a fire-resistant layer with a thickness of 0.16mm. (3) Preparation of the insulating layer: SS1: Preparation of insulating layer particles: The raw materials with a content of 33VA (EVA-vinyl acetate copolymer), polyethylene mLLDPE, maleic anhydride, ceramic powder, kaolin, aluminum hydroxide, magnesium hydroxide, antioxidant 1010 / 168, UV531, UV5411 and crosslinking agent TAIC are mixed according to the weight parts shown in Table 1. After mixing and plasticizing, the mixture is extruded and granulated to obtain insulating layer particles; SS2: An insulating layer of 2.6 mm is extruded on the outside of the mica tape and crosslinked by irradiation to obtain an environmentally friendly fire-resistant power cable.

[0038] Example 3 An environmentally friendly fire-resistant power cable is manufactured using the following steps: (1) Prepare 8 strands of type II tin-plated copper conductor; (2) Preparation of refractory layer: S1: Acidification treatment is performed on calcined mica paper to obtain calcined mica paper with carboxyl groups; S2: Place glass fibers in a hydrogen peroxide solution to modify them; slowly stir polyurethane acrylate with deionized water to avoid forming bubbles, while adding thickener polyvinyl alcohol and lubricant silicone oil, and let the mixture stand for 60 minutes to allow the bubbles to dissipate, thus obtaining a water-based polyurethane adhesive; add the modified glass fibers to the water-based polyurethane adhesive, and spray the water-based polyurethane adhesive solution containing the modified glass fibers onto the surface of calcined mica paper with carboxyl groups, and then dry it; S3: Hot pressing, cooling, and then winding and slitting to obtain mica tape; S4: Two layers of mica tape are wrapped around the conductor. The mica side of the mica tape is close to the stranded copper conductor, and the glass fiber side of the mica tape is close to the insulation layer. The overlap rate is 25%, forming a fire-resistant layer with a thickness of 0.12mm. (3) Preparation of the insulating layer: SS1: Preparation of insulating layer particles: EVA ethylene-vinyl acetate copolymer, polyethylene mLLDPE, maleic anhydride, ceramic powder, kaolin, aluminum hydroxide, magnesium hydroxide, antioxidant DLTP and crosslinking agent TAIC are mixed according to the components shown in Table 1 by weight. After mixing and plasticizing, the mixture is extruded and granulated to obtain insulating layer particles. SS2: An insulation layer of 2.4mm is extruded onto the outside of mica tape and cross-linked by irradiation to obtain an environmentally friendly fire-resistant power cable.

[0039] Table 1 Raw materials for insulation layers Example 4 An environmentally friendly fire-resistant power cable differs from Example 1 in that the calcined mica paper is not acidified and the surface of the calcined mica paper does not contain carboxyl groups.

[0040] Example 5 An environmentally friendly fire-resistant power cable differs from Example 1 in that the glass fiber is not treated with hydrogen peroxide.

[0041] Test case Voltage tests were conducted on the cables from Examples 1 to 5. All cables from Examples 1 to 5 did not break down under AC 3.5kV / 5min conditions. The cables from Examples 1 to 5 had a pH value ≥ 4.3, conductivity ≤ 10μs / mm, and light transmittance not less than 60%. This indicates that these cables exhibit good insulation performance and safety under higher voltages, and possess chemical stability and low conductivity, which contributes to their long-term use in humid or corrosive environments.

[0042] In the halogen gas release test, the cables of Examples 1-5 had HCl and HBr contents ≤0.5% and HF contents ≤0.1%. This demonstrates the low halogen release properties of these cables under fire conditions.

[0043] The cables from Examples 1 to 5 were subjected to a high-temperature aging test at 110°C. The mechanical properties before and after aging are as follows: 1) Before aging: Tensile strength ≥ 6.5 MPa, elongation at break ≥ 200%; 2) Under the conditions of (150±2)℃ and (10×24)h, the change rate of tensile strength after aging is ≤±30%, and the change rate of elongation at break after aging is ≤±30%. This indicates that the cables in Examples 1-5 have good mechanical strength and sufficient elasticity before aging, making them suitable for use in dynamic or flexible environments. The cables in Examples 1-5 retain their mechanical properties well under high-temperature aging conditions, exhibiting outstanding high-temperature resistance and maintaining good mechanical properties in high-temperature environments.

[0044] The cables of Examples 1-5 were tested for thermal elongation after cross-linking at a temperature of (200±3)℃, a load time of 15 min, a mechanical pressure of 0.20 MPa, a maximum elongation of 100% under load, and a maximum permanent deformation of 25% after cooling. This indicates that these cables have good thermal stability and resilience after cross-linking, and can effectively cross-link at high temperatures without losing their original physical properties. Furthermore, the cables of Examples 1-5 passed the IEC332-3 bundled burning test, with the smoke concentration meeting the technical requirements of IEC1034-2, the corrosive gas content meeting the recommended values ​​specified in IEC754-2, and the insulated cores passing the single-core vertical burning test specified in IPCEAS-19-81.

[0045] The flame retardant properties of the mica tapes from Examples 1-5 were further tested. Specifically, the vertical burning performance of the samples was determined according to GB / T 2408—2008 "Determination of Burning Performance of Plastics—Horizontal and Vertical Methods," with sample dimensions of 125 mm in length, 13 mm in width, and 3 mm in thickness. The limiting oxygen index of the samples was determined according to GB / T 2406.1-2008 "Determination of Burning Behavior of Plastics—Oxygen Index Method—Part 1: Guidelines," with sample dimensions of 125 mm in length, 6.5 mm in width, and 3 mm in thickness. The results are shown in Table 2.

[0046] Table 2. Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Vertical flammability rating FV-0 FV-0 FV-0 FV-0 FV-0 Limiting oxygen index 45.7 41.7 44.8 32.6 35.1 Whether it melts or drips no no no no no As shown in Table 2, compared with Examples 4 and 5, Example 1, by acidifying and modifying the calcined mica paper with glass fiber, significantly improved the limiting oxygen index. Examples 4 and 5, however, only involved glass fiber modification; acidifying the calcined mica paper did not improve the limiting oxygen index. The reason for this is likely that only by combining acidification and glass fiber modification can a heat-resistant structure be formed, enhancing the adhesion between the mica paper and glass fiber in the mica tape.

[0047] Further fire resistance tests were conducted on the mica tapes of Examples 1 to 5. The test results of the simple fire resistance test, the fire resistance test under spraying (Class W), and the fire resistance test under mechanical impact (Class Z) are shown in Table 3.

[0048] Table 3. As shown in Table 2, compared with Examples 4 and 5, Example 1, after acidification and glass fiber modification of the calcined mica paper, was able to pass the Class W fire resistance test with spraying and the Class Z fire resistance test with mechanical impact. This is because the modification of the glass fiber improved its mechanical properties, and the acidification treatment of the calcined mica paper helped to form a waterproof structure, thus enhancing its fire resistance.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An environmentally friendly fire-resistant power cable, characterized in that, It includes a multi-stranded copper conductor, a refractory layer, and an insulating layer. The stranded copper conductor is sequentially covered with the refractory layer and the insulating layer. The refractory layer is mica tape. The insulating layer is made of the following components in parts by weight: 15-25 parts ethylene-vinyl acetate copolymer, 10-15 parts polyethylene, 10-15 parts maleic anhydride, 15-25 parts ceramic powder, 3-7 parts kaolin, 20-30 parts aluminum hydroxide, 15-25 parts magnesium hydroxide, 1-3 parts antioxidant, and 0.5-3 parts crosslinking agent.

2. The environmentally friendly fire-resistant power cable according to claim 1, characterized in that, The method for preparing the mica tape includes the following steps: (S1) Acidification treatment is performed on calcined mica paper to obtain calcined mica paper with carboxyl groups; (S2) Spray a water-based adhesive solution containing glass fibers onto the surface of calcined mica paper with carboxyl groups; (S3) Hot pressing, cooling and then winding and cutting to obtain a mica tape with mica on one side and glass fiber on the other side.

3. The environmentally friendly fire-resistant power cable according to claim 2, characterized in that, The glass fiber is a modified glass fiber, and the preparation method of the modified glass fiber includes the following steps: placing the glass fiber in a hydrogen peroxide solution.

4. The environmentally friendly fire-resistant power cable according to claim 2, characterized in that, The water-based adhesive is a polyurethane water-based adhesive.

5. The environmentally friendly fire-resistant power cable according to claim 2, characterized in that, The preparation method of the polyurethane waterborne adhesive includes the following steps: slowly stirring polyurethane acrylate with deionized water to avoid the formation of bubbles, while adding thickener and lubricant, and obtaining the polyurethane waterborne adhesive after defoaming.

6. The environmentally friendly fire-resistant power cable according to claim 1, characterized in that, The thickness of the refractory layer is 0.12 to 0.16 mm; the refractory layer includes two layers of mica tape, which are composed of a first mica tape and a second mica tape wrapped around each other, and the stranded copper conductor is wrapped with the first mica tape and the second mica tape in sequence, with an overlap rate of 25% to 30%.

7. An environmentally friendly fire-resistant power cable according to claim 2 or 6, characterized in that, The mica side of the mica tape is close to the stranded copper conductor, and the glass fiber side of the mica tape is close to the insulating layer.

8. The environmentally friendly fire-resistant power cable according to claim 1, characterized in that, The thickness of the insulating layer is 2.4 to 2.6 mm.

9. The environmentally friendly fire-resistant power cable according to claim 1, characterized in that, The conductor is a Class II tin-plated copper conductor, and more preferably a seven-strand stranded wire.

10. The method for preparing the environmentally friendly fire-resistant power cable according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Preparation of multi-strand stranded copper conductor; (2) Wrap mica tape around the conductor to form a fire-resistant layer; (3) An insulation layer of 2.4-2.6 mm is extruded on the outside of the mica tape and cross-linked by irradiation to obtain an environmentally friendly fire-resistant power cable.

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