Low smoke zero halogen flame retardant power cable

Abstract

This invention discloses a low-smoke halogen-free flame-retardant power cable, belonging to the technical field of flame-retardant power cables. The cable comprises a core, a wrapping layer, and a sheath layer. The sheath layer is made of the following raw materials in parts by weight: 70-80 parts thermoplastic polyurethane elastomer, 20-30 parts maleic anhydride-grafted POE, 15-20 parts inorganic flame retardant, 8-16 parts halogen-free flame retardant, 1-2 parts antioxidant, 0.5-1 part ultraviolet absorber, and 2-3 parts lubricant. The halogen-free flame retardant molecules contain phosphorus, silicon, nitrogen, Schiff bases, and oxazine ring structures, achieving a dual flame-retardant mechanism in both the condensed and gaseous phases through synergistic effects, significantly improving flame-retardant performance and inhibiting dripping. The cable of this invention has the advantages of low smoke, halogen-free, highly efficient flame retardancy, and good heat resistance, making it particularly suitable for power transmission scenarios with high safety and durability requirements, such as charging piles.

Description

Technical Field

[0001] This invention belongs to the field of flame-retardant power cable technology, specifically, it relates to a low-smoke halogen-free flame-retardant power cable. Background Technology

[0002] With the rapid development of the new energy vehicle industry, charging piles, as a key supporting facility, have seen a continuous increase in both construction scale and usage frequency. Charging pile cables, serving as the "energy bridge" connecting charging piles and new energy vehicles, directly determine charging efficiency, safety, and equipment lifespan, and have become one of the key supporting components affecting the high-quality development of the charging pile industry.

[0003] In the structure of charging pile cables, the sheath, as the outermost protective structure, is in direct contact with the external environment. During use, it is frequently bent and dragged, and bears a large charging current for a long time, which leads to prominent problems such as cable heating and insulation aging.

[0004] The choice and performance of the sheath material directly affect the overall reliability and safety of the cable. Conventional charging pile cables mostly use polyvinyl chloride (PVC) for their sheaths. While this material is inexpensive and easy to process, it contains halogens. In extreme situations such as fires, it can release large amounts of toxic and harmful hydrogen halide gases and dense fumes, posing serious health risks. It can also obstruct vision, corrode equipment, and significantly hinder fire rescue and evacuation, failing to meet the safety requirements of charging pile locations with dense crowds and sophisticated equipment. Furthermore, PVC has poor weather resistance, abrasion resistance, and low-temperature performance. Long-term outdoor use can lead to aging, cracking, and breakage, resulting in decreased cable insulation performance and potential short circuits and leakage, severely impacting the normal operation of the charging pile and potentially causing equipment damage and personal injury.

[0005] In conclusion, there is an urgent need to invent a low-smoke, halogen-free, flame-retardant power cable to meet the higher technical requirements of the charging pile cable field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-smoke halogen-free flame-retardant power cable.

[0007] The objective of this invention can be achieved through the following technical solutions: A low-smoke halogen-free flame-retardant power cable includes a cable core, a wrapping layer, and a sheath layer.

[0008] Preferably, the material of the wrapping layer is polyester tape.

[0009] Preferably, the material of the sheath layer comprises the following raw materials in parts by weight: 70-80 parts thermoplastic polyurethane elastomer, 20-30 parts maleic anhydride-grafted POE, 15-20 parts inorganic flame retardant, 8-16 parts halogen-free flame retardant, 1-2 parts antioxidant, 0.5-1 part ultraviolet absorber, and 2-3 parts lubricant.

[0010] Preferably, the inorganic flame retardant is ultrafine aluminum hydroxide with a surface treated with a silane coupling agent, and D50 ≤ 1.5 μm.

[0011] Preferably, the antioxidant is a phenolic antioxidant.

[0012] Preferably, the ultraviolet absorber is a benzotriazole ultraviolet absorber.

[0013] Preferably, the lubricant is one of zinc stearate, calcium stearate, and oleamide.

[0014] Preferably, the halogen-free flame retardant is prepared by the following steps: A1. In a dry three-necked flask (with a magnetic stir bar, nitrogen protection, and a spherical condenser), add aminopropyl double-ended head and tetrahydrofuran, stir to dissolve, then add p-hydroxybenzaldehyde and anhydrous sodium sulfate, then heat to 66-70℃ and reflux for 4-5 hours. After the reaction is completed, after post-treatment, compound 1 is obtained. A2. In a dry three-necked flask (with a magnetic stir bar and nitrogen protection), add p-aminophenol and anhydrous tetrahydrofuran. After stirring evenly, add sodium hydroxide powder in batches. After the addition is complete, stir at room temperature for 30-40 minutes. Then, dissolve dimethylphosphonic chloride in anhydrous tetrahydrofuran and slowly add it dropwise to the flask through a dropping funnel (using an ice-water bath during the dropping process). After the dropping is complete, stir the reaction at room temperature for 3-4 hours. After the reaction is complete, and after post-processing, compound 2 is obtained. A3. In a dry three-necked flask (with a magnetic stir bar, nitrogen protection, and a spherical condenser), add compound 2 and tetrahydrofuran. After stirring evenly, place the apparatus under ice-water bath conditions and add formaldehyde solution (concentration 37%) dropwise. After the addition is complete, add compound 1, stir evenly, and then heat to 66-70℃ and reflux for 5-7 hours. After the reaction is complete, and after post-processing, obtain a halogen-free flame retardant.

[0015] Preferably, the ratio of the aminopropyl double-ended end cap to p-hydroxybenzaldehyde is 24.8g:28.1-30.3g.

[0016] Preferably, the ratio of p-aminophenol, sodium hydroxide powder and dimethylphosphonic chloride is 11.5-12.7g:4.2g:11.2g.

[0017] Preferably, the ratio of compound 2, formaldehyde solution and compound 1 is 39.2-41.5g:30g:45.6g.

[0018] The reaction formula for step A1 is as follows: The reaction equations for steps A2-A3 are as follows: This invention prepares a halogen-free flame retardant through the above three steps. During the preparation process, attention must be paid to the amount of raw materials used in each step. In step A1, the molar ratio of aminopropyl double-ended compound to p-hydroxybenzaldehyde should be close to 1:2, and p-hydroxybenzaldehyde should be in excess to ensure complete reaction. In step A2, the molar ratio of p-aminophenol to dimethylphosphonochloride should be close to 1:1, and p-aminophenol should be in excess to retain the amino group. Finally, in step A3, the molar ratio of compound 1 to compound 2 should be close to 1:2, and compound 1 should be in excess to ensure complete reaction and obtain a halogen-free flame retardant.

[0019] As can be seen from the above reaction formula, the halogen-free flame retardant molecule prepared by this invention contains multiple flame-retardant groups. Phosphorus generates phosphoric acid and metaphosphoric acid at high temperatures, promoting dehydration and char formation while inhibiting the release of combustible gases. Silicon forms a dense silicon-carbon layer during combustion, isolating heat and oxygen. The Schiff base structure contains nitrogen, which releases non-combustible gases during combustion, diluting oxygen and promoting char formation. These multiple elements work synergistically to achieve a dual flame-retardant mechanism in both the condensed and gaseous phases. This significantly improves the flame-retardant performance of the matrix. Finally, the oxazine ring, a thermosetting structural unit with a high thermal decomposition temperature, not only inhibits dripping but also improves the heat resistance of the matrix.

[0020] The beneficial effects of this invention are: The cable produced by this invention is halogen-free and will not release large amounts of toxic and harmful hydrogen halide gas and dense smoke when burned, thus avoiding harm to human health. This invention achieves a dual flame-retardant mechanism of condensed phase and gas phase by using a self-made halogen-free flame retardant, which promotes char formation, isolates oxygen and heat, and releases non-combustible gases, thus significantly improving the flame-retardant performance of cables. The oxazine ring in the flame retardant has a high thermal decomposition temperature, which can inhibit dripping, improve the heat resistance of the cable, reduce the risk of fire spread and long-term working stability; Using polyurethane elastomer as the sheath provides better weather resistance and reduces aging and cracking compared to traditional PVC sheaths, thus extending the cable's service life.

[0021] In summary, the cable produced by this invention is low-smoke and halogen-free, with excellent flame retardant and heat resistance properties, and is particularly suitable for the field of charging pile cable technology. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 Preparation of halogen-free flame retardants: A1. In a dry three-necked flask (with a magnetic stir bar, nitrogen protection, and a spherical condenser), add 24.8 g of aminopropyl double-ended flask and 150 mL of tetrahydrofuran. After stirring and dissolving, add 28.1 g of p-hydroxybenzaldehyde and 10 g of anhydrous sodium sulfate. Then heat to 66 °C and reflux for 4 h. After the reaction is complete, cool to room temperature and remove anhydrous sodium sulfate by atmospheric pressure filtration. Then, rotary evaporate the solution, dissolve it in toluene, wash with saturated brine, add anhydrous sodium sulfate to the organic layer and dry it. Remove the solvent by rotary evaporation and dry under vacuum to obtain compound 1. A2. In a dry three-necked flask (with a magnetic stir bar and nitrogen protection), add 23.0 g of p-aminophenol and 100 mL of anhydrous tetrahydrofuran. After stirring evenly, add 8.4 g of sodium hydroxide powder in batches. After the addition is complete, stir at room temperature for 30 min. Then, dissolve 22.4 g of dimethylphosphonic chloride in 100 mL of anhydrous tetrahydrofuran and slowly add it dropwise to the flask through a dropping funnel (using an ice-water bath during the dropping process). After the addition is complete, stir the reaction at room temperature for 3 h. After the reaction is complete, filter, concentrate the filtrate under reduced pressure, and purify it by silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 1:3) to obtain compound 2. A3. In a dry three-necked flask (with a magnetic stir bar, nitrogen protection, and a spherical condenser), add 39.2 g of compound 2 and 150 mL of tetrahydrofuran. After stirring evenly, place the apparatus in an ice-water bath and add 30 g of formaldehyde solution (37% concentration) dropwise. After the addition is complete, add 45.6 g of compound 1 and stir evenly. Then heat to 66 °C and reflux for 5 h. After the reaction is complete, cool to room temperature and remove the solvent by rotary evaporation. Add toluene and deionized water to separate the layers. Take the toluene layer and wash it once with saturated sodium carbonate solution, three times with saturated sodium bicarbonate solution, and once with saturated brine. Then separate the organic phase layer, dry it with anhydrous sodium sulfate, and remove the solvent by rotary evaporation to obtain a halogen-free flame retardant. Preparation of sheath layer material: 70 parts of thermoplastic polyurethane elastomer were dried at 80℃ for 2 hours. According to the formula, the dried thermoplastic polyurethane elastomer, 20 parts of maleic anhydride-grafted POE, 15 parts of inorganic flame retardant (ultrafine aluminum hydroxide with D50≤1.5μm treated with silane coupling agent KH-550), 8 parts of halogen-free flame retardant, 1 part of antioxidant 1010, 0.5 parts of ultraviolet absorber UV-328 and 2 parts of zinc stearate were put into a high-speed mixer and mixed evenly. The mixture was then extruded through a twin-screw extruder and granulated to obtain the sheath layer material. A low-smoke, halogen-free, flame-retardant power cable is prepared by the following steps: B1. Copper wires are placed in a stranding machine to be stranded to obtain stranded copper wires, which are then used as conductors. Cross-linked polyethylene insulation is extruded over the conductors and then cross-linked by electron beam irradiation (dose 12Mrad) to form the cable core. B2. Multiple cable cores are twisted into a cable and a layer of polyester tape is wrapped around the outside to form a wrapping layer; then, the sheath material is extruded and wrapped on the surface of the wrapping layer using an extruder. After the sheath is extruded, it is cooled by passing it through a cooling water tank to obtain a low-smoke halogen-free flame-retardant power cable.

[0024] Example 2 Preparation of halogen-free flame retardants: A1. In a dry three-necked flask (with a magnetic stir bar, nitrogen protection, and a spherical condenser), add 24.8 g of aminopropyl double-ended compound and 150 mL of tetrahydrofuran. After stirring and dissolving, add 30.3 g of p-hydroxybenzaldehyde and 10 g of anhydrous sodium sulfate. Then heat to 70 °C and reflux for 5 h. After the reaction is complete, cool to room temperature and remove anhydrous sodium sulfate by atmospheric pressure filtration. Then, rotary evaporate the mixture, dissolve it in toluene, wash it with saturated brine, add anhydrous sodium sulfate to the organic layer and dry it. Remove the solvent by rotary evaporation and dry under vacuum to obtain compound 1. A2. In a dry three-necked flask (with a magnetic stir bar and nitrogen protection), add 25.4 g of p-aminophenol and 100 mL of anhydrous tetrahydrofuran. After stirring evenly, add 8.4 g of sodium hydroxide powder in portions. After the addition is complete, stir at room temperature for 40 min. Then, dissolve 22.4 g of dimethylphosphonic chloride in 100 mL of anhydrous tetrahydrofuran and slowly add it dropwise to the flask through a dropping funnel (using an ice-water bath during the dropping process). After the addition is complete, stir the reaction at room temperature for 4 h. After the reaction is complete, filter, concentrate the filtrate under reduced pressure, and purify it by silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 1:3) to obtain compound 2. A3. In a dry three-necked flask (with a magnetic stir bar, nitrogen protection, and a spherical condenser), add 41.5 g of compound 2 and 150 mL of tetrahydrofuran. After stirring evenly, place the apparatus in an ice-water bath and add 30 g of formaldehyde solution (37% concentration) dropwise. After the addition is complete, add 45.6 g of compound 1 and stir evenly. Then heat to 70 °C and reflux for 7 h. After the reaction is complete, cool to room temperature and remove the solvent by rotary evaporation. Add toluene and deionized water to separate the layers. Take the toluene layer and wash it once with saturated sodium carbonate solution, three times with saturated sodium bicarbonate solution, and once with saturated brine. Then separate the organic phase layer, dry it with anhydrous sodium sulfate, and remove the solvent by rotary evaporation to obtain a halogen-free flame retardant. Preparation of sheath layer material: 75 parts of thermoplastic polyurethane elastomer were dried at 80℃ for 2 hours. According to the formula, the dried thermoplastic polyurethane elastomer, 25 parts of maleic anhydride-grafted POE, 17.5 parts of inorganic flame retardant (ultrafine aluminum hydroxide with D50≤1.5μm treated with silane coupling agent KH-550), 12 parts of halogen-free flame retardant, 1.5 parts of antioxidant 1010, 0.75 parts of ultraviolet absorber UV-328 and 2.5 parts of calcium stearate were put into a high-speed mixer and mixed evenly. The mixture was then extruded through a twin-screw extruder and granulated to obtain the sheath layer material. A low-smoke, halogen-free, flame-retardant power cable is prepared by the following steps: B1. Copper wires are placed in a stranding machine to be stranded to obtain stranded copper wires, which are then used as conductors. Cross-linked polyethylene insulation is extruded over the conductors and then cross-linked by electron beam irradiation (dose 12Mrad) to form the cable core. B2. Multiple cable cores are twisted into a cable and a layer of polyester tape is wrapped around the outside to form a wrapping layer; then, the sheath material is extruded and wrapped on the surface of the wrapping layer using an extruder. After the sheath is extruded, it is cooled by passing it through a cooling water tank to obtain a low-smoke halogen-free flame-retardant power cable.

[0025] Example 3 The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the sheath material is prepared through the following steps: 80 parts of thermoplastic polyurethane elastomer were dried at 80℃ for 2 hours. According to the formula, the dried thermoplastic polyurethane elastomer, 30 parts of maleic anhydride-grafted POE, 20 parts of inorganic flame retardant (ultrafine aluminum hydroxide with D50≤1.5μm treated with silane coupling agent KH-550), 16 parts of halogen-free flame retardant, 2 parts of antioxidant 1010, 1 part of ultraviolet absorber UV-328 and 3 parts of oleic amide were put into a high-speed mixer and mixed evenly. The mixture was then extruded through a twin-screw extruder and granulated to obtain the sheath layer material. A low-smoke, halogen-free, flame-retardant power cable is prepared by the following steps: B1. Copper wires are placed in a stranding machine to be stranded to obtain stranded copper wires, which are then used as conductors. Cross-linked polyethylene insulation is extruded over the conductors and then cross-linked by electron beam irradiation (dose 12Mrad) to form the cable core. B2. Multiple cable cores are twisted into a cable and a layer of polyester tape is wrapped around the outside to form a wrapping layer; then, the sheath material is extruded and wrapped on the surface of the wrapping layer using an extruder. After the sheath is extruded, it is cooled by passing it through a cooling water tank to obtain a low-smoke halogen-free flame-retardant power cable.

[0026] Comparative Example 1 The difference between this comparative example and Example 3 is that in this comparative example, an equal amount of ammonium polyphosphate is used to replace the halogen-free flame retardant to obtain the sheath material.

[0027] Comparative Example 2 It uses commercially available PVC sheath material, manufactured by Shandong Taikai Cable Co., Ltd., model ZH-90.

[0028] The sheath materials obtained in Examples 1, 2, and 3 were subjected to the following performance tests compared with Comparative Examples 1 and 2: The oxygen index was determined according to GB / T 2406.2 standard; Smoke density was determined using GB / T 8323.2 standard; The heat distortion temperature was determined according to GB / T 1634.2 standard. The measured results of the above performance are shown in Table 1: Table 1 As can be seen from the test results in Table 1, the cable prepared by the embodiment of the present invention has significantly better flame retardancy and heat resistance than the comparative example, and is low-smoke and halogen-free, making it particularly suitable for the field of charging pile cable technology.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A low-smoke halogen-free flame-retardant power cable, comprising a cable core, a wrapping layer, and a sheath layer, characterized in that, The sheath layer comprises the following raw materials in parts by weight: 70-80 parts thermoplastic polyurethane elastomer, 20-30 parts maleic anhydride-grafted POE, 15-20 parts inorganic flame retardant, 8-16 parts halogen-free flame retardant, 1-2 parts antioxidant, 0.5-1 part ultraviolet absorber, and 2-3 parts lubricant.

2. The low-smoke halogen-free flame-retardant power cable according to claim 1, characterized in that, The inorganic flame retardant is ultrafine aluminum hydroxide with a surface treated with a silane coupling agent, and D50≤1.5μm.

3. The low-smoke halogen-free flame-retardant power cable according to claim 1, characterized in that, The antioxidant is a phenolic antioxidant.

4. The low-smoke halogen-free flame-retardant power cable according to claim 1, characterized in that, The ultraviolet absorber is a benzotriazole ultraviolet absorber.

5. A low-smoke halogen-free flame-retardant power cable according to claim 1, characterized in that, The lubricant is one of zinc stearate, calcium stearate, and oleamide.

6. The low-smoke halogen-free flame-retardant power cable according to claim 1, characterized in that, The halogen-free flame retardant is prepared by the following steps: A1. In a flask, add aminopropyl double-ended and tetrahydrofuran, stir to dissolve, then add p-hydroxybenzaldehyde and anhydrous sodium sulfate, and reflux at 66-70℃ for 4-5 hours. After the reaction is complete, compound 1 is obtained. A2. Add p-aminophenol and anhydrous tetrahydrofuran to a flask, stir well, add sodium hydroxide powder, stir at room temperature for 30-40 min, then dissolve dimethylphosphonic chloride in anhydrous tetrahydrofuran and add it dropwise to the flask. After the addition is complete, stir the reaction at room temperature for 3-4 h. The reaction is complete, and compound 2 is obtained. A3. In a flask, add compound 2 and tetrahydrofuran, stir well, and then add formaldehyde solution (concentration 37%) dropwise under an ice-water bath. After the addition is complete, add compound 1, stir well, and reflux at 66-70℃ for 5-7 hours. Once the reaction is complete, a halogen-free flame retardant is obtained.

7. A low-smoke halogen-free flame-retardant power cable according to claim 6, characterized in that, The ratio of aminopropyl double-ended to p-hydroxybenzaldehyde is 24.8g:28.1-30.3g.

8. A low-smoke halogen-free flame-retardant power cable according to claim 6, characterized in that, The ratio of p-aminophenol, sodium hydroxide powder, and dimethylphosphonochloride is 11.5-12.7g:4.2g:11.2g.

9. A low-smoke halogen-free flame-retardant power cable according to claim 6, characterized in that, The ratio of compound 2, formaldehyde solution and compound 1 is 39.2-41.5g:30g:45.6g.

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