Low-smoke halogen-free high-flame-retardant new energy cable material and processing technology thereof

Abstract

The application discloses a low-smoke halogen-free high-flame-retardant new energy cable material and a processing technology thereof, and belongs to the technical field of cable materials, and mainly relates to how to further improve the halogen-free low-smoke flame-retardant performance, mechanical performance and insulation performance of the new energy cable material, and specifically comprises the following components by weight: 100 parts of polyethylene, 40-48 parts of flame-retardant powder, 12-16 parts of composite polysiloxane, 10-15 parts of composite reinforcing material and 2-4 parts of auxiliary additive. The synergistic effect between the prepared flame-retardant powder, the composite polysiloxane and the composite reinforcing material is utilized to further improve the halogen-free low-smoke flame-retardant performance, the mechanical performance and the insulation performance of the prepared new energy cable material.

Description

Technical Field

[0001] This invention relates to the field of cable material technology, specifically to a low-smoke, halogen-free, high flame-retardant new energy cable material and its processing technology. Background Technology

[0002] The rapid development of the new energy industry has placed stringent demands on the comprehensive performance of cable materials. Low smoke and halogen-free properties, as well as high flame retardancy, are the core performance indicators of new energy cables. At the same time, excellent mechanical and electrical insulation properties must also be taken into account to adapt to the complex operating environment of new energy equipment. Although the polyethylene-based new energy cable materials currently on the market have basic insulation and processing properties, they generally suffer from poor compatibility and uneven dispersion of flame retardant components with the matrix during the flame retardant modification process. The smoke suppression and flame retardant effect of a single flame retardant system is limited, making it difficult to meet the high-level requirements of halogen-free and low smoke flame retardancy. During combustion, they are prone to producing a large amount of smoke and toxic gases, posing safety hazards.

[0003] Currently, inorganic flame-retardant fillers added to improve flame retardancy tend to form stress concentration points in the matrix, leading to a decrease in the tensile strength, elongation at break, and other mechanical properties of the material, and even problems such as embrittlement and cracking. This makes it impossible to meet the mechanical load requirements during cable laying and use. At the same time, the internal microstructure of traditional modified cable materials has defects such as micropores and gaps, and the grain boundary characteristics of inorganic fillers can also easily cause charge migration, which reduces the breakdown voltage of the material, damages the insulation performance, and affects the electrical safety and service life of new energy cables.

[0004] In addition, the synergistic effect between the functional components of common cable materials is limited. Most of the modification links such as flame retardancy, toughening, reinforcement and insulation are independent of each other, making it difficult to achieve simultaneous improvement of various properties. Although some modification methods can improve a single property, they will sacrifice other properties, and cannot meet the comprehensive requirements of new energy cables for halogen-free low smoke, high flame retardancy, high mechanical strength and high insulation.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a low-smoke, halogen-free, high flame-retardant new energy cable material and its processing technology, in order to solve the technical problem of how to further improve the halogen-free, low-smoke, flame-retardant, mechanical, and insulation properties of new energy cable materials.

[0007] The objective of this invention can be achieved through the following technical solution: a low-smoke, halogen-free, high flame-retardant new energy cable material, comprising the following components by weight: 100 parts polyethylene, 40-48 parts flame-retardant powder, 12-16 parts composite polysiloxane, 10-15 parts composite reinforcing material, and 2-4 parts auxiliary additives.

[0008] The auxiliary additives comprise the following components by weight: 0.8-1 parts dicumyl peroxide, 1-1.5 parts calcium stearate, and 0.5-0.8 parts antioxidant 1010;

[0009] The flame retardant powder is prepared as follows: DOPD derivative is added to a reaction vessel containing N,N-dimethylformamide, heated to 35-40℃ and stirred until the DOPD derivative is completely dissolved. Then, 2,6-diisocyanate toluene is added and stirred for 20-30 minutes. Finally, ammonium polyphosphate, emulsifier OP-10 and dibutyltin dilaurate are added, and the temperature is further increased to 80-90℃. The reaction is carried out for 8-10 hours. After the reaction is completed, the mixture is filtered, and the product is washed 3-4 times with N,N-dimethylformamide and anhydrous ethanol, respectively. The product is then placed in a vacuum drying oven and dried at 60℃ to constant weight to obtain flame retardant powder, wherein the DOPD derivative is a DOPD with hydroxyl modification.

[0010] Furthermore, the ratio of the DOPD derivative, N,N-dimethylformamide, 2,6-diisocyanate toluene, ammonium polyphosphate, emulsifier OP-10, and dibutyltin dilaurate is 9g:300-340mL:6g:80-90g:1g:0.3g.

[0011] Furthermore, the preparation method of the DOPD derivative is as follows: DOPO is added to a reaction vessel containing anhydrous ethanol, and stirred until the DOPO is completely dissolved. Then, paraformaldehyde and diethanolamine are added, the temperature is raised to 50-60℃, and the reaction is stirred for 10-12 hours. After the reaction is completed, the mixture is filtered, washed 3-5 times with anhydrous ethanol, and the product is placed in a vacuum drying oven and dried at 60℃ to constant weight to obtain the DOPD derivative. The ratio of DOPO, anhydrous ethanol, paraformaldehyde, and diethanolamine is 70-72g:300mL:30g:34.7g.

[0012]

[0013] Furthermore, the preparation method of the composite polysiloxane is as follows: boric acid is added to a reaction vessel containing anhydrous ethanol, heated to 50-60℃, and stirred until the boric acid is completely dissolved. Then, hydroxyl-terminated polydimethylsiloxane is added, the temperature is first raised to 70-75℃ and reacted for 3-4 hours, and then the temperature is raised to 110-120℃ and reacted for another 1-2 hours. After the reaction is completed, the mixture is transferred to a drying oven and dried at 110℃ until no bubbles are generated, thus obtaining the composite polysiloxane. The ratio of boric acid, anhydrous ethanol and hydroxyl-terminated polydimethylsiloxane is 5g:50-60mL:95g.

[0014]

[0015] Furthermore, the preparation method of the composite reinforcing material is as follows: maleic anhydride, allyl acetate, acrylamide, azobisisobutyronitrile and butyl acetate are added to a reaction vessel and reacted at 70-80℃ under an argon atmosphere for 5-6 hours. After the reaction is completed, the mixture is filtered, and the product is washed 3-4 times with butyl acetate and n-hexane, respectively. Then, it is placed in a vacuum drying oven and dried at 60℃ to constant weight to obtain the composite reinforcing material.

[0016]

[0017] Furthermore, the ratio of maleic anhydride, allyl acetate, acrylamide, azobisisobutyronitrile and butyl acetate is 4.8-5.0g:2.8-3.0g:0.6g:0.08g:50mL.

[0018] The present invention also proposes a processing technology for a low-smoke, halogen-free, high flame-retardant new energy cable material, comprising the following steps:

[0019] S1. Add polyethylene, flame retardant powder, composite polysiloxane, composite reinforcing material and auxiliary additives into a high-speed mixer and mix at 80-100℃ and 400-600r / min for 5-10 minutes to obtain a premix.

[0020] S2. Add the premixed material to a twin-screw extruder, melt-blend and extrude it to uniformly coat the outside of the new energy cable conductor, and then immediately put it into a vulcanizing tube. After maintaining it at 180-200℃ for 10-20 minutes, take it out and cool it to room temperature in a cold water bath to obtain the new energy cable material.

[0021] Furthermore, in step S2, the temperatures of the eight temperature zones of the twin-screw extruder, arranged from the feed end toward the die head, are sequentially set to 130℃, 135℃, 140℃, 140℃, 145℃, 145℃, 145℃, and 140℃, and the spindle speed of the twin-screw extruder is 80 r / min.

[0022] The present invention has the following beneficial effects:

[0023] 1. The flame-retardant powder of this invention is based on DOPD derivatives with a phosphorus-phenanthroline structure, combined with the phosphorus and nitrogen flame-retardant elements of ammonium polyphosphate, forming a phosphorus-nitrogen synergistic gas-phase-condensed-phase two-phase flame-retardant system. The three-dimensional polymer shell coating on its surface can also improve the dispersibility and thermal stability of the flame-retardant components. The boron-oxygen bonds and siloxane network contained in the composite polysiloxane will form a dense silicon-boron carbon layer at high temperature, isolating oxygen and heat transfer. At the same time, the decomposition products of siloxane can dilute flammable gases, achieving a low-smoke and smoke-suppressing effect. The ternary copolymer structure of the composite reinforcing material introduces polar functional groups, which can form an interface bond with the flame-retardant powder and composite polysiloxane, so that each flame-retardant component is uniformly dispersed in the polyethylene matrix, avoiding local flame-retardant failure. The three work together, with the flame-retardant carbonization of phosphorus and nitrogen, the physical isolation of silicon and boron, and the interfacial compatibility of functional groups, significantly improving the halogen-free low-smoke flame-retardant level of the material and achieving a highly efficient flame-retardant and smoke-suppressing effect.

[0024] 2. The three-dimensional polymer shell on the surface of the flame-retardant powder of the present invention weakens the interfacial compatibility problem between inorganic flame-retardant fillers and organic matrix, reduces stress concentration points, and the boron-oxygen cross-linked siloxane network of the composite polysiloxane has good flexibility and elasticity, which can form an elastic toughening phase in the polyethylene matrix to alleviate stress transmission when the material is subjected to external force. The composite reinforcing material is a ternary copolymer structure containing carboxyl anhydride, ester and amide groups. These polar functional groups can form intermolecular forces with polyethylene molecular chains and other components. At the same time, its polymer chains can form an entangled network in the matrix, which plays a role in physical reinforcement. The three work together to optimize the dispersion of the flame-retardant powder, the elastic toughening of the composite polysiloxane, and the network reinforcement of the composite reinforcing material. This not only makes up for the problem of decreased mechanical properties of the material caused by the addition of flame-retardant fillers, but also further improves the tensile strength and elongation at break of the material, so that the material has both flame retardancy and excellent mechanical properties.

[0025] 3. The three-dimensional polymer shell on the surface of the flame-retardant powder of this invention is an insulating organic structure that encapsulates inorganic particles of ammonium polyphosphate. This avoids the decrease in insulation performance caused by grain boundary defects of inorganic fillers. At the same time, the presence of phosphorus and nitrogen elements does not introduce conductive impurities, thus maintaining the insulating properties of the flame-retardant components. The siloxane backbone of the composite polysiloxane is a non-polar insulating structure. The dense network formed by boron-oxygen crosslinking can reduce micropores and gaps inside the material, reducing the probability of charge migration and breakdown. Its good film-forming properties can also improve the structural density of the material. The ternary copolymer structure of the composite reinforcing material is an insulating organic polymer. Its tight bonding with the matrix and each component can fill the micro-voids in the matrix, reduce the conductive channels inside the material, and improve the structural stability of the material. This avoids structural defects caused by external forces or heat that affect insulation. The three work together: the insulating coating of the flame-retardant powder, the dense insulating network of the composite polysiloxane, and the structural densification of the composite reinforcing material interact to optimize the internal microstructure of the material, reduce insulation defects, improve the breakdown voltage of the material, and ensure the excellent insulation performance of the cable material. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0027] In this application, the polyethylene is selected from Xinhongshou Plastics (Suzhou) Co., Ltd., and its grade is BPD2167.

[0028] In this application, the paraformaldehyde is selected from Beijing Jingtu Hengsheng Chemical Technology Co., Ltd., CAS No. 30525-89-4;

[0029] In this application, the hydroxyl-terminated polydimethylsiloxane is selected from Hubei Xinjiecheng Chemical Technology Co., Ltd., CAS No. 88497-56-7.

[0030] Example 1

[0031] This embodiment provides a processing technology for a low-smoke, halogen-free, high flame-retardant new energy cable material, including the following steps:

[0032] S1. Preparation of DOPD derivatives

[0033] Weigh 70g of DOPO and add it to a reaction vessel containing 300mL of anhydrous ethanol. Stir until the DOPO is completely dissolved, then add 30g of paraformaldehyde and 34.7g of diethanolamine. Heat to 50℃ and stir for 10h. After the reaction is complete, filter and wash three times with anhydrous ethanol. Place the product in a vacuum drying oven and dry at 60℃ to constant weight to obtain the DOPD derivative.

[0034] During the reaction, DOPO first undergoes a nucleophilic addition reaction of the depolymerized formaldehyde monomer with the carbonyl group via a pH bond to generate a DOPO intermediate containing a hydroxymethyl group. Subsequently, this intermediate undergoes a Mannich-type condensation reaction with diethanolamine, forming a CN bond through dehydration. This allows the phosphenanthrene structure of DOPO to be linked to the nitrogen atom of diethanolamine via a methylene group, ultimately yielding the DOPO derivative.

[0035] S2. Preparation of flame-retardant powder

[0036] Weigh 45g of DOPD derivative and add it to a reaction vessel containing 1500mL of N,N-dimethylformamide. Heat to 35℃ and stir until the DOPD derivative is completely dissolved. Then add 30g of 2,6-diisocyanate toluene and stir for another 20min. Finally, add 400g of ammonium polyphosphate, 5g of emulsifier OP-10 and 1.5g of dibutyltin dilaurate. Continue to heat to 80℃ and react for 8h. After the reaction is complete, filter and wash the product three times with N,N-dimethylformamide and anhydrous ethanol, respectively. Place it in a vacuum drying oven and dry at 60℃ to constant weight to obtain flame retardant powder.

[0037] During the reaction, the DOPO derivative undergoes stepwise addition polymerization of hydroxyl and isocyanate groups with 2,6-diisocyanate toluene to generate a urethane prepolymer containing terminal isocyanate groups. Subsequently, under the dispersion of OP-10 emulsifier, the prepolymer is adsorbed onto the surface of ammonium polyphosphate particles. The terminal isocyanate groups and the active hydrogen on the surface of ammonium polyphosphate are further cross-linked by addition under the catalysis of dibutyltin dilaurate to form a three-dimensional polymer shell encapsulating the ammonium polyphosphate. After washing and drying, flame-retardant powder is obtained.

[0038] S3, Preparation of composite polysiloxane

[0039] Weigh 50g of boric acid and add it to a reaction vessel containing 500mL of anhydrous ethanol. Heat the mixture to 50℃ and stir until the boric acid is completely dissolved. Then add 950g of hydroxyl-terminated polydimethylsiloxane. First, heat the mixture to 70℃ and react for 3 hours, then heat it to 110℃ and continue reacting for 1 hour. After the reaction is complete, transfer the mixture to a drying oven and dry it at 110℃ until no bubbles are generated to obtain the composite polysiloxane.

[0040] During the reaction, boric acid first undergoes an esterification reaction with anhydrous ethanol under hydrothermal conditions to generate triethyl borate. Subsequently, triethyl borate undergoes an ester exchange reaction with the terminal silanol groups, releasing ethanol and forming a BO-Si bonded prepolymer. Upon further heating, the ester exchange is fully completed and small molecules are removed. At the same time, the residual boron hydroxyl groups further condense with the silanol groups to construct a composite polysiloxane network with boron-oxygen bonds as crosslinking points. Finally, the residual small molecules are removed by drying to obtain a stable boron-modified polydimethylsiloxane product.

[0041] S4. Preparation of composite reinforced materials

[0042] Weigh out 48g maleic anhydride, 28g allyl acetate, 6g acrylamide, 0.8g azobisisobutyronitrile and 500mL butyl acetate and add them to the reaction vessel. React at 70℃ under an argon atmosphere for 5h. After the reaction is complete, filter the product and wash it three times with butyl acetate and n-hexane, respectively. Then place it in a vacuum drying oven and dry it at 60℃ to constant weight to obtain the composite reinforced material.

[0043] During the reaction, under an argon atmosphere, azobisisobutyronitrile decomposes under heating conditions to generate isobutyronitrile free radicals, which initiate free radical copolymerization of maleic anhydride, allyl acetate, and acrylamide. Through chain initiation, chain propagation, and chain termination, a crude ternary random copolymer containing carboxyl anhydride, ester, and amide groups is formed. Unreacted monomers and impurities are then removed by filtration and stepwise washing with butyl acetate and n-hexane to obtain a polymeric composite reinforced material.

[0044] S5. Preparation of new energy cable materials

[0045] Weigh out the following by weight: 0.8 parts dicumyl peroxide, 1 part calcium stearate, and 0.5 parts antioxidant 1010. Mix them evenly to obtain the auxiliary additive.

[0046] Weigh out the following by weight: 100 parts polyethylene, 40 parts flame retardant powder, 12 parts composite polysiloxane, 10 parts composite reinforcing material and 2 parts auxiliary additives. Add them to a high-speed mixer and mix at 80°C and 400 r / min for 5 minutes to obtain a premix.

[0047] The premixed material is added to a twin-screw extruder. The twin-screw extruder has eight temperature zones set from the feed end toward the die head, with temperatures of 130℃, 135℃, 140℃, 140℃, 145℃, 145℃, 145℃, and 140℃ respectively. The spindle speed is 80 r / min. The material is melt-blended and extruded, uniformly coating the outside of the new energy cable conductor. It is then immediately placed into a vulcanizing tube and kept at 180℃ for 10 minutes. After that, it is taken out and cooled to room temperature in a cold water bath to obtain the new energy cable material.

[0048] During the reaction, under high-speed mixing, the raw materials undergo only physical dispersion. Calcium stearate plays a lubricating and dispersing role, allowing the flame-retardant powder, composite polysiloxane, composite reinforcing material, and auxiliary additives to be uniformly dispersed in the softened polyethylene matrix to form a premix. Subsequently, the premix is ​​completely melted and plasticized by a twin-screw extruder, and the components form a melt system with good interfacial bonding and coat the conductor. Then, in a heated vulcanizing tube, dicumyl peroxide rapidly decomposes to generate free radicals, initiating three-dimensional chemical cross-linking between polyethylene, composite polysiloxane, and composite reinforcing material, forming a dense interpenetrating network structure. Finally, the material is cooled in a cold water bath, allowing the cross-linked material structure to quickly solidify, resulting in a low-smoke, halogen-free, and highly flame-retardant new energy cable material.

[0049] Example 2

[0050] This embodiment provides a processing technology for a low-smoke, halogen-free, high flame-retardant new energy cable material, including the following steps:

[0051] S1. Preparation of DOPD derivatives

[0052] Weigh 71g of DOPO and add it to a reaction vessel containing 300mL of anhydrous ethanol. Stir until the DOPO is completely dissolved, then add 30g of paraformaldehyde and 34.7g of diethanolamine. Heat to 55℃ and stir for 11h. After the reaction is complete, filter and wash four times with anhydrous ethanol. Place the product in a vacuum drying oven and dry at 60℃ to constant weight to obtain the DOPD derivative.

[0053] S2. Preparation of flame-retardant powder

[0054] Weigh 45g of DOPD derivative and add it to a reaction vessel containing 1600mL of N,N-dimethylformamide. Heat to 35℃ and stir until the DOPD derivative is completely dissolved. Then add 30g of 2,6-diisocyanate toluene and stir for another 25 minutes. Finally, add 425g of ammonium polyphosphate, 5g of emulsifier OP-10, and 1.5g of dibutyltin dilaurate. Continue to heat to 85℃ and react for 9 hours. After the reaction is complete, filter the product and wash it three times with N,N-dimethylformamide and anhydrous ethanol, respectively. Then place it in a vacuum drying oven and dry it at 60℃ to constant weight to obtain flame retardant powder.

[0055] S3, Preparation of composite polysiloxane

[0056] Weigh 50g of boric acid and add it to a reaction vessel containing 550mL of anhydrous ethanol. Heat the mixture to 55℃ and stir until the boric acid is completely dissolved. Then add 950g of hydroxyl-terminated polydimethylsiloxane. First, heat the mixture to 70℃ and react for 3.5h. Then, heat the mixture to 115℃ and continue reacting for 1.5h. After the reaction is complete, transfer the mixture to a drying oven and dry it at 110℃ until no bubbles are generated to obtain the composite polysiloxane.

[0057] S4. Preparation of composite reinforced materials

[0058] Weigh out 49g maleic anhydride, 29g allyl acetate, 6g acrylamide, 0.8g azobisisobutyronitrile and 500mL butyl acetate and add them to the reaction vessel. React at 75℃ under an argon atmosphere for 5.5h. After the reaction is complete, filter the product and wash it three times with butyl acetate and n-hexane, respectively. Then place it in a vacuum drying oven and dry it at 60℃ to constant weight to obtain the composite reinforced material.

[0059] S5. Preparation of new energy cable materials

[0060] Weigh out the following components by weight: 0.9 parts dicumyl peroxide, 1.2 parts calcium stearate, and 0.7 parts antioxidant 1010. Mix them thoroughly to obtain the auxiliary additive.

[0061] Weigh out the following by weight: 100 parts polyethylene, 44 parts flame retardant powder, 14 parts composite polysiloxane, 12 parts composite reinforcing material and 3 parts auxiliary additives, add them to a high-speed mixer, and mix at 90°C and 500 r / min for 8 minutes to obtain a premix.

[0062] The premixed material is added to a twin-screw extruder. The twin-screw extruder has eight temperature zones set from the feed end toward the die head, with temperatures of 130℃, 135℃, 140℃, 140℃, 145℃, 145℃, 145℃, and 140℃ respectively. The spindle speed is 80 r / min. The material is melt-blended and extruded, uniformly coating the outside of the new energy cable conductor. It is then immediately placed into a vulcanizing tube and kept at 190℃ for 15 minutes. After that, it is taken out and cooled to room temperature in a cold water bath to obtain the new energy cable material.

[0063] Example 3

[0064] This embodiment provides a processing technology for a low-smoke, halogen-free, high flame-retardant new energy cable material, including the following steps:

[0065] S1. Preparation of DOPD derivatives

[0066] Weigh 72g of DOPO and add it to a reaction vessel containing 300mL of anhydrous ethanol. Stir until the DOPO is completely dissolved, then add 30g of paraformaldehyde and 34.7g of diethanolamine. Heat to 60℃ and stir for 12h. After the reaction is complete, filter and wash 5 times with anhydrous ethanol. Place the product in a vacuum drying oven and dry at 60℃ to constant weight to obtain the DOPD derivative.

[0067] S2. Preparation of flame-retardant powder

[0068] Weigh 45g of DOPD derivative and add it to a reaction vessel containing 1700mL of N,N-dimethylformamide. Heat to 40℃ and stir until the DOPD derivative is completely dissolved. Then add 30g of 2,6-diisocyanate toluene and stir for another 30 minutes. Finally, add 450g of ammonium polyphosphate, 5g of emulsifier OP-10, and 1.5g of dibutyltin dilaurate. Continue to heat to 90℃ and react for 10 hours. After the reaction is complete, filter the product and wash it four times with N,N-dimethylformamide and anhydrous ethanol, respectively. Place the product in a vacuum drying oven and dry it at 60℃ to constant weight to obtain flame retardant powder.

[0069] S3, Preparation of composite polysiloxane

[0070] Weigh 50g of boric acid and add it to a reaction vessel containing 600mL of anhydrous ethanol. Heat the mixture to 60℃ and stir until the boric acid is completely dissolved. Then add 950g of hydroxyl-terminated polydimethylsiloxane. First, heat the mixture to 75℃ and react for 4 hours, then heat it to 120℃ and continue reacting for 2 hours. After the reaction is complete, transfer the mixture to a drying oven and dry it at 110℃ until no bubbles are generated to obtain the composite polysiloxane.

[0071] S4. Preparation of composite reinforced materials

[0072] Weigh out 50g maleic anhydride, 30g allyl acetate, 6g acrylamide, 0.8g azobisisobutyronitrile and 500mL butyl acetate and add them to the reaction vessel. React at 80℃ under an argon atmosphere for 6 hours. After the reaction is complete, filter the product and wash it four times with butyl acetate and n-hexane, respectively. Then place it in a vacuum drying oven and dry it at 60℃ to constant weight to obtain the composite reinforced material.

[0073] S5. Preparation of new energy cable materials

[0074] Weigh out the following by weight: 1 part dicumyl peroxide, 1.5 parts calcium stearate, and 0.8 parts antioxidant 1010. Mix them evenly to obtain the auxiliary additive.

[0075] Weigh out the following by weight: 100 parts polyethylene, 48 parts flame retardant powder, 16 parts composite polysiloxane, 15 parts composite reinforcing material and 4 parts auxiliary additives, add them to a high-speed mixer, and mix at 100℃ and 600r / min for 10 minutes to obtain a premix.

[0076] The premixed material is added to a twin-screw extruder. The twin-screw extruder has eight temperature zones set from the feed end toward the die head, with temperatures of 130℃, 135℃, 140℃, 140℃, 145℃, 145℃, 145℃, and 140℃ respectively. The spindle speed is 80 r / min. The material is melt-blended and extruded, uniformly coating the outside of the conductor of the new energy cable. It is then immediately placed into a vulcanizing tube and kept at 200℃ for 20 minutes. After that, it is taken out and cooled to room temperature in a cold water bath to obtain the new energy cable material.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 3 is that step S2 is omitted, and the flame retardant powder in step S5 is replaced with the DOPD derivative prepared in step S1.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 3 is that steps S1 and S2 are omitted, and the flame retardant powder in step S5 is replaced with DOPO in step S1.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 3 is that step S3 is omitted, and the hydroxyl-terminated polydimethylsiloxane in step S3 is used instead of the composite polysiloxane in step S5.

[0083] Comparative Example 4

[0084] The difference between this comparative example and Example 3 is that step S4 is omitted and no composite reinforcing material is added in step S5.

[0085] Performance testing:

[0086] The tensile strength and elongation at break of a low-smoke, halogen-free, high flame-retardant new energy cable material prepared in Examples 1-3 and Comparative Examples 1-4 were determined in accordance with the standard GB / T 1040.1-2025 "Determination of tensile properties of plastics - Part 1: General".

[0087] The breakdown voltage of a low-smoke halogen-free high flame-retardant new energy cable material prepared in Examples 1-3 and Comparative Examples 1-4 was determined according to the standard GB / T 1408.1-2016 "Electrical strength test method for insulating materials - Part 1: Test under power frequency" to reflect the insulation performance of the material.

[0088] The halogen-free, low-smoke flame retardant rating of a low-smoke, halogen-free, high flame-retardant new energy cable material prepared in Examples 1-3 and Comparative Examples 1-4 was determined according to the standard GB / T 19666-2019 "General Rules for Flame Retardant and Fire-Resistant Wires, Cables or Optical Cables". The specific test results are shown in Table 1 below:

[0089] Table 1 - Performance Test Data of Samples

[0090] Group item Halogen-free low smoke flame retardant grade Tensile strength (MPa) Elongation at break (%) Breakdown voltage (kV) Example 1 WDZAN 24.5 318 25.8 Example 2 WDZAN 24.8 322 26.0 Example 3 WDZAN 25.2 327 26.3 Comparative Example 1 WDZCN 20.5 298 24.1 Comparative Example 2 WDZCN 18.1 256 19.4 Comparative Example 3 WDZBN 16.2 231 20.1 Comparative Example 4 WDZCN 14.8 207 21.3

[0091] Data Analysis:

[0092] Comparative analysis of the data in Table 1 above shows that the low-smoke halogen-free high flame-retardant new energy cable material prepared by this invention has a tensile strength of 25.2 MPa, an elongation at break of 327%, a breakdown voltage of 26.3 kV, and a halogen-free low-smoke flame-retardant rating of WDZAN.

[0093] Comparative Example 1 eliminated the flame retardant powder preparation step and replaced the flame retardant powder with DOPD derivative. Due to the lack of the phosphorus-nitrogen synergistic flame retardant system of ammonium polyphosphate and the coating and dispersion effect of the three-dimensional polymer shell, the flame retardant component of DOPD derivative alone could not form a gas-phase-condensed phase two-phase flame retardant effect. Moreover, the decreased dispersibility easily caused local flame retardant failure, resulting in the material's halogen-free low smoke flame retardant grade dropping to WDZCN, tensile strength decreasing to 20.5MPa, elongation at break decreasing to 298%, and breakdown voltage decreasing to 24.1kV.

[0094] Comparative Example 2 eliminated the preparation of DOPD derivatives and flame retardant powder, and directly replaced the flame retardant powder with DOPO. Because DOPO was not modified with hydroxyl groups and modified with ammonium polyphosphate, the synergistic effect of phosphorus and nitrogen between the phosphaphenanthrene structure and ammonium polyphosphate was lost. There was also no three-dimensional polymer shell to optimize the interface compatibility. Not only was the flame retardant char formation effect greatly weakened, but also a large number of stress concentration points were generated due to the poor bonding between the inorganic filler and the matrix. As a result, its flame retardant grade was WDZCN, the tensile strength was only 18.1MPa, the elongation at break was 256%, and the breakdown voltage was 19.4kV.

[0095] Comparative Example 3 eliminated the preparation of composite polysiloxane and replaced it with hydroxyl-terminated polydimethylsiloxane. Due to the lack of the BO-Si bond crosslinking network formed by boric acid modification, a dense silicon boron carbon layer could not be formed at high temperature, and the physical isolation and smoke suppression effects were greatly reduced. In addition, there was no elastic crosslinking phase to relieve stress transmission, and the micropores and gaps inside the material increased, resulting in the flame retardant rating being reduced to WDZBN, with a tensile strength of 16.2 MPa, an elongation at break of 231%, and a breakdown voltage of 20.1 kV.

[0096] Comparative Example 4, without the addition of composite reinforcing material, lacked a ternary copolymer structure containing carboxyl anhydride, ester, and amide groups. This prevented the formation of intermolecular forces and entanglement networks with other components, resulting in uneven dispersion of flame-retardant components, localized flame-retardant failure, loss of physical reinforcement and structural densification, and increased micro-pores within the material, forming conductive channels. Consequently, the flame retardant rating was WDZCN, the tensile strength was 14.8 MPa, the elongation at break was 207%, and the breakdown voltage was 21.3 kV.

[0097] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-smoke, halogen-free, high flame-retardant new energy cable material, characterized in that, It includes the following components by weight: 100 parts polyethylene, 40-48 parts flame retardant powder, 12-16 parts composite polysiloxane, 10-15 parts composite reinforcing material and 2-4 parts auxiliary additives; The method for preparing the flame retardant powder is as follows: DOPD derivative is added to a reaction vessel containing N,N-dimethylformamide, heated to 35-40℃ and stirred until the DOPD derivative is completely dissolved, then 2,6-diisocyanate toluene is added, and stirred for another 20-30 minutes. Finally, ammonium polyphosphate, emulsifier OP-10 and dibutyltin dilaurate are added, and the temperature is further increased to 80-90℃. The reaction is carried out for 8-10 hours. After the reaction is completed, post-processing is performed to obtain the flame retardant powder, wherein the DOPD derivative is a DOPD with hydroxyl modification.

2. The low-smoke, halogen-free, high flame-retardant new energy cable material according to claim 1, characterized in that, The ratio of the DOPD derivative, N,N-dimethylformamide, toluene 2,6-diisocyanate, ammonium polyphosphate, emulsifier OP-10, and dibutyltin dilaurate is 9g:300-340mL:6g:80-90g:1g:0.3g.

3. The low-smoke, halogen-free, high flame-retardant new energy cable material according to claim 1, characterized in that, The preparation method of the DOPD derivative is as follows: DOPO is added to a reaction vessel containing anhydrous ethanol and stirred until DOPO is completely dissolved. Then, paraformaldehyde and diethanolamine are added, the temperature is raised to 50-60℃, and the reaction is stirred for 10-12 hours. After the reaction is completed, the mixture is filtered and washed 3-5 times with anhydrous ethanol. The product is placed in a vacuum drying oven and dried at 60℃ to constant weight to obtain the DOPD derivative. The ratio of DOPO, anhydrous ethanol, paraformaldehyde, and diethanolamine is 70-72g:300mL:30g:34.7g.

4. The low-smoke, halogen-free, high flame-retardant new energy cable material according to claim 3, characterized in that, The preparation method of the composite polysiloxane is as follows: boric acid is added to a reaction vessel containing anhydrous ethanol, heated to 50-60℃, and stirred until the boric acid is completely dissolved. Then, hydroxyl-terminated polydimethylsiloxane is added, the temperature is first raised to 70-75℃ and reacted for 3-4 hours, and then the temperature is raised to 110-120℃ and reacted for another 1-2 hours. After the reaction is completed, the mixture is transferred to a drying oven and dried at 110℃ until no bubbles are generated, thus obtaining the composite polysiloxane. The ratio of boric acid, anhydrous ethanol and hydroxyl-terminated polydimethylsiloxane is 5g:50-60mL:95g.

5. The low-smoke, halogen-free, high flame-retardant new energy cable material according to claim 1, characterized in that, The method for preparing the composite reinforcing material is as follows: maleic anhydride, allyl acetate, acrylamide, azobisisobutyronitrile and butyl acetate are added to a reaction vessel and reacted at 70-80℃ under an argon atmosphere for 5-6 hours. After the reaction is completed, the mixture is filtered, and the product is washed 3-4 times with butyl acetate and n-hexane, respectively. Then, it is placed in a vacuum drying oven and dried at 60℃ to constant weight to obtain the composite reinforcing material.

6. The low-smoke, halogen-free, high flame-retardant new energy cable material according to claim 5, characterized in that, The ratio of maleic anhydride, allyl acetate, acrylamide, azobisisobutyronitrile, and butyl acetate is 4.8-5.0g:2.8-3.0g:0.6g:0.08g:50mL.

7. The processing technology of a low-smoke, halogen-free, high flame-retardant new energy cable material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Add polyethylene, flame retardant powder, composite polysiloxane, composite reinforcing material and auxiliary additives into a high-speed mixer and mix at 80-100℃ and 400-600r / min for 5-10 minutes to obtain a premix. S2. Add the premixed material to a twin-screw extruder, melt-blend and extrude it to uniformly coat the outside of the new energy cable conductor, and then immediately put it into a vulcanizing tube. After maintaining it at 180-200℃ for 10-20 minutes, take it out and cool it to room temperature in a cold water bath to obtain the new energy cable material.

8. The processing technology of a low-smoke, halogen-free, high flame-retardant new energy cable material according to claim 7, characterized in that, In step S2, the temperatures of the eight temperature zones of the twin-screw extruder, set from the feed end toward the die head, are sequentially set to 130℃, 135℃, 140℃, 140℃, 145℃, 145℃, 145℃, and 140℃, and the spindle speed of the twin-screw extruder is 80 r / min.

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