Flame-retardant fireproof cable and preparation method thereof

Abstract

The invention discloses a flame-retardant fireproof cable and a preparation method thereof, and belongs to the technical field of cable preparation. The preparation method of the flame-retardant fireproof cable comprises the following steps: uniformly mixing the high-density polyethylene, the linear low-density polyethylene, the ethylene-vinyl acetate copolymer, the antioxidant, the flame retardant, the calcium stearate, the stearic acid, the polyethylene wax, the compatilizer and the cross-linking agent, and heating to 170-190 DEG C; and extruding through a double-screw extruder and wrapping the surface of a cable core material to form a sheath layer, thereby obtaining the flame-retardant fireproof cable. The flame retardant is formed by grafting polymethylhydrosiloxane modified by gamma-(methacryloyloxy) propyl trimethoxy silane to a polyphosphazene microsphere; the inside of the polyphosphazene microsphere is coated with a nano calcium carbonate embedding material; the content in the nano calcium carbonate embedded material comprises a nitrogen and phosphorus-containing DOPO derivative, hexamethylenediamine tetra (methylene phosphonic acid) cobalt and phenyl lanthanum phosphonate; and the flame retardant is introduced to improve the flame retardant property and mechanical property of the polyethylene cable material.

Description

Technical Field

[0001] The invention belongs to the technical field of cable preparation, and particularly relates to a flame-retardant and fireproof cable and a preparation method thereof. Background Art

[0002] Polyethylene is highly valued for its excellent tensile and flexural strength. It also exhibits exceptional flexibility and maintains its properties over a wide temperature range, making it an ideal choice for cable manufacturing. However, due to limitations in its chemical structure, polyethylene's flame retardancy is relatively weak, a drawback that significantly restricts its application. To address this issue, a common approach currently used in the industry is to add large amounts of inorganic flame retardants, such as aluminum hydroxide and magnesium hydroxide, to polyethylene. While this approach can improve flame retardancy to a certain extent, the addition of large amounts of inorganic flame retardants inevitably leads to a decrease in the mechanical properties of polyethylene. It also adversely affects the material's processing, increasing production difficulties. Therefore, researchers urgently need to develop new and efficient flame retardants and effectively incorporate them into polyethylene. This approach aims to significantly enhance the flame retardancy of polyethylene without compromising its inherent excellent mechanical properties, thereby expanding its application and meeting the needs of a wider range of industries. Summary of the Invention

[0003] The purpose of the present invention is to provide a flame retardant and fireproof cable and a preparation method thereof, which are used to solve the technical problem of improving the flame retardant properties of polyethylene materials without reducing the original good mechanical properties of polyethylene materials.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a flame-retardant and fire-resistant cable, the flame-retardant and fire-resistant cable comprising a cable core material obtained by twisting copper wires, and a sheath layer wrapped around the surface of the cable core material, the method comprising the following steps: High-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant, flame retardant, calcium stearate, stearic acid, polyethylene wax, compatibilizer, and cross-linking agent are uniformly mixed and heated to 170-190° C., and then extruded through a twin-screw extruder and wrapped around the surface of the cable core material to form a sheath layer, thereby obtaining the flame-retardant and fire-resistant cable.

[0005] As a preferred technical solution of the present invention, the mass ratio of the high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant, flame retardant, calcium stearate, stearic acid, polyethylene wax, compatibilizer, and cross-linking agent is 40-50:15-25:45-55:1-2:5-7:1-2:1-2:7-9:8-10:2-3.

[0006] As a preferred technical solution of the present invention, the compatibilizer is maleic anhydride grafted polyethylene.

[0007] As a preferred technical solution of the present invention, the cross-linking agent is diisopropyl peroxide.

[0008] As a preferred technical solution of the present invention, the antioxidant is antioxidant 1010.

[0009] As a preferred technical solution of the present invention, the method for preparing the flame retardant comprises the following steps: S1. Mix dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and triethylamine, stir for 30-40 minutes, add N-hydroxyethyl acrylamide, add carbon tetrachloride dropwise in an ice-water bath, and react at room temperature for 10-15 hours. After the reaction, the product is diluted with dichloromethane, extracted with a saturated sodium chloride solution, and the organic layer is dehydrated and then distilled under reduced pressure. The product is purified using a developing agent prepared from petroleum ether and ethyl acetate in a volume ratio of 1:10, and the solvent is removed by distillation under reduced pressure to obtain a nitrogen-phosphorus DOPO derivative. The nitrogen-phosphorus DOPO derivative is obtained by grafting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) onto the hydroxyl end of N-hydroxyethyl acrylamide, and the phosphorus-phosphorus DOPO derivative is obtained, which exerts a phosphorus-nitrogen synergistic flame retardant effect in the flame retardant process. S2. Hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate were mixed, refluxed and stirred at 80-90° C. for 3-5 hours, transferred to a polytetrafluoroethylene autoclave, and subjected to hydrothermal reaction at 100° C. for 24 hours. The mixture was washed, centrifuged, and dried to obtain hexamethylenediaminetetramethylenephosphonic acid cobalt; S3, taking phenylphosphonic acid, deionized water and lanthanum nitrate hexahydrate, mixing, reflux stirring at 80-90 ° C for 3-5 hours, transferring to a polytetrafluoroethylene autoclave, constant temperature hydrothermal reaction at 100 ° C for 24 hours, washing, centrifuging, and drying to obtain lanthanum phenylphosphonate; The synergistic effect of hexamethylenediaminetetramethylenephosphonic acid cobalt and lanthanum phenylphosphonate synthesized by hydrothermal reaction as flame retardant additives and nitrogen-phosphorus-containing DOPO derivatives improves the thermal stability of the material while achieving a good condensed phase flame retardant effect in the matrix. The catalytic effect is used to form a dense carbon layer to enhance the barrier effect. S4. Mix the nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, phenyl phosphonic acid lanthanum, sodium dodecylbenzenesulfonate, and anhydrous ethanol, stir ultrasonically for 10-20 minutes, add calcium chloride solution, stir at 40-50° C. for 1-2 hours, then add sodium carbonate solution and continue stirring for 1-2 hours, collect the precipitate by centrifugation, wash, and dry at 60° C. for 6-8 hours to obtain a nano-calcium carbonate embedding material; use nano-calcium carbonate as a wall material to embed the nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, and phenyl phosphonic acid lanthanum; add sodium dodecylbenzenesulfonate to improve the dispersibility and stability of the nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, and phenyl phosphonic acid lanthanum; S5. Mix 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, and nano-calcium carbonate embedding material, ultrasonically disperse for 30-40 minutes, add hexachlorocyclotriphosphazene, stir at 45°C for 7-9 hours, centrifuge, wash the solid phase, and vacuum dry to obtain polyphosphazene microspheres; synthesize polyphosphazene microspheres using 4,4'-dihydroxydiphenyl sulfone and hexachlorocyclotriphosphazene as comonomers and the nano-calcium carbonate embedding material as a template; S6. In a nitrogen atmosphere, polymethyl hydrogen siloxane and toluene are mixed, an ethanol solution of chloroplatinic acid is added, and the mixture is stirred at 65-75° C. for 30-40 minutes. The mixture is heated to 90-95° C., γ-(methacryloyloxy)propyltrimethoxysilane is added, and the mixture is refluxed with stirring for 4-6 hours. The mixture is purified by distillation under reduced pressure to obtain modified polymethyl hydrogen siloxane, so that γ-(methacryloyloxy)propyltrimethoxysilane is grafted onto the polymethyl hydrogen siloxane. S7. Mix the polyphosphazene microspheres, modified polymethylhydrogensiloxane and toluene, stir ultrasonically for 40-60 minutes, filter, wash the solid phase, and vacuum dry to obtain the flame retardant.

[0010] As a preferred technical solution of the present invention, in step S1, the dosage ratio of dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triethylamine, N-hydroxyethyl acrylamide, and carbon tetrachloride is 200-300 mL: 20-25 g: 2.4-3.6 g: 12-16 mL: 10.7-13.8 mL.

[0011] As a preferred technical solution of the present invention, in step S2, the dosage ratio of hexamethylenediaminetetramethylenephosphonic acid, deionized water and cobalt nitrate hexahydrate is 8-10 g:200 mL:15.8-17.4 g.

[0012] As a preferred technical solution of the present invention, in step S3, the dosage ratio of phenylphosphonic acid, deionized water and lanthanum nitrate hexahydrate is 8-10 g:200 mL:7.5-10.2 g.

[0013] As a preferred technical solution of the present invention, in step S4, the dosage ratio of the nitrogen-phosphorus DOPO derivative, cobalt hexamethylenediaminetetramethylenephosphonate, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, anhydrous ethanol, calcium chloride solution, and sodium carbonate solution is 1.8-2.8 g: 0.6-0.8 g: 0.2-0.3 g: 0.11-0.23 g: 50 mL: 250 mL: 500 mL; the concentration of the calcium chloride solution is 1 mol / L; and the concentration of the sodium carbonate solution is 1 mol / L.

[0014] As a preferred technical solution of the present invention, in step S5, the dosage ratio of the 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, nano-calcium carbonate embedding material, and hexachlorocyclotriphosphazene is 1.2-1.5 g:100 mL:3-4 mL:2.2-2.8 g:1-1.2 g.

[0015] As a preferred technical solution of the present invention, in step S6, the dosage ratio of the polymethylhydrogensiloxane, toluene, chloroplatinic acid, anhydrous ethanol, and γ-(methacryloyloxy)propyltrimethoxysilane is 3.2-4.4 g: 200 mL: 0.04-0.06 g: 25 mL: 9.7-11.3 g.

[0016] As a preferred technical solution of the present invention, in step S7, the mixing ratio of the polyphosphazene microspheres, modified polymethylhydrogensiloxane and toluene is 2.3-3.4 g: 5.8-7.2 g: 100 mL.

[0017] The flame retardant and fireproof cable is prepared by the above preparation method.

[0018] Beneficial effects of the present invention: The present invention prepares a flame retardant based on polyphosphazene microspheres, and grafts organic silicon on the surface of the polyphosphazene. On the one hand, the flexibility of the cable is enhanced. On the other hand, during the combustion process, oxygen-containing phosphoric acid generated by the decomposition of the flame retardant promotes the dehydration and carbonization of the organic silicon, so that silicon migrates to the polyethylene surface to form a silicon layer, forming a physical barrier. A silicon dioxide-filled residual carbon layer is generated to form a dense and continuous residual carbon layer, which prevents further combustion of the polyethylene substrate. Furthermore, nano-calcium carbonate embedding material-polyphosphazene microspheres is prepared. During the combustion process, the polyphosphazene forms a carbon layer, and the nano-calcium carbonate decomposes to generate carbon dioxide, which has a synergistic flame retardant effect. The nitrogen-phosphorus DOPO derivative, cobalt hexamethylenediaminetetramethylenephosphonate, and lanthanum phenylphosphonate embedded in the nano-calcium carbonate are released. Through the synergistic effect of the three, a condensed phase is formed to have a flame retardant effect. At the same time, the formation of the carbon layer is catalyzed to form a denser carbon layer, thereby improving the barrier effect. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0020] Example 1 A method for preparing a flame retardant and fireproof cable comprises the following steps: The cable core material obtained by twisting the copper wires and the sheath material are uniformly mixed and heated to 170°C, and then extruded through a twin-screw extruder and wrapped on the surface of the cable core material to form a sheath layer, thereby obtaining a flame retardant and fireproof cable; The sheath material includes 40 parts by mass of high-density polyethylene, 15 parts by mass of linear low-density polyethylene, 45 parts by mass of ethylene-vinyl acetate copolymer, 1 part by mass of antioxidant 1010, 5 parts by mass of flame retardant, 1 part by mass of calcium stearate, 1 part by mass of stearic acid, 7 parts by mass of polyethylene wax, 8 parts by mass of maleic anhydride grafted polyethylene, and 2 parts by mass of diisopropyl peroxide; The preparation method of the flame retardant comprises the following steps: S1. Mix dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and triethylamine, stir for 30 minutes, add N-hydroxyethyl acrylamide, add carbon tetrachloride dropwise in an ice-water bath, and react at room temperature for 10 hours. After the reaction, the product is diluted with dichloromethane, extracted with a saturated sodium chloride solution, and the organic layer is dehydrated and then distilled under reduced pressure. The product is purified using a developing agent prepared by petroleum ether and ethyl acetate in a volume ratio of 1:10, and then the solvent is removed by distillation under reduced pressure to obtain a nitrogen-phosphorus DOPO derivative; the ratio of dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triethylamine, N-hydroxyethyl acrylamide, and carbon tetrachloride is 200 mL:20 g:2.4 g:12 mL:10.7 mL; S2. Hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate were mixed, refluxed and stirred at 80° C. for 3 h, transferred to a polytetrafluoroethylene autoclave, and hydrothermally reacted at 100° C. for 24 h, washed, centrifuged, and dried to obtain hexamethylenediaminetetramethylenephosphonic acid cobalt; the ratio of hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate was 8 g:200 mL:15.8 g; S3. Phenylphosphonic acid, deionized water, and lanthanum nitrate hexahydrate were mixed, refluxed and stirred at 80° C. for 3 h, transferred to a polytetrafluoroethylene autoclave, and subjected to a hydrothermal reaction at 100° C. for 24 h. The mixture was washed, centrifuged, and dried to obtain lanthanum phenylphosphonate; the ratio of phenylphosphonic acid, deionized water, and lanthanum nitrate hexahydrate was 8 g:200 mL:7.5 g. S4. The nitrogen-phosphorus-containing DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, and anhydrous ethanol are mixed, ultrasonically stirred for 10 minutes, a calcium chloride solution is added, and the mixture is stirred at 40° C. for 1 hour. Then, a sodium carbonate solution is added and the mixture is stirred for 1 hour. The precipitate is collected by centrifugation, washed, and dried at 60° C. for 6 hours to obtain a nano-calcium carbonate embedding material; the amount ratio of the nitrogen-phosphorus-containing DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, anhydrous ethanol, calcium chloride solution, and sodium carbonate solution is 1.8 g: 0.6 g: 0.2 g: 0.11 g: 50 mL: 250 mL: 500 mL; the concentration of the calcium chloride solution is 1 mol / L; the concentration of the sodium carbonate solution is 1 mol / L; S5. Mix 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, and nano-calcium carbonate embedding material, ultrasonically disperse for 30 minutes, add hexachlorocyclotriphosphazene, stir at 45°C for 7 hours, centrifuge, wash the solid phase, and vacuum dry to obtain polyphosphazene microspheres; the ratio of 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, nano-calcium carbonate embedding material, and hexachlorocyclotriphosphazene is 1.2 g:100 mL:3 mL:2.2 g:1 g; S6. In a nitrogen atmosphere, polymethyl hydrogen siloxane and toluene were mixed, an ethanol solution of chloroplatinic acid was added, and the mixture was stirred at 65° C. for 30 min. The mixture was heated to 90° C., γ-(methacryloyloxy)propyltrimethoxysilane was added, and the mixture was refluxed and stirred for 4 h. The mixture was purified by vacuum distillation to obtain modified polymethyl hydrogen siloxane; the ratio of the polymethyl hydrogen siloxane, toluene, chloroplatinic acid, anhydrous ethanol, and γ-(methacryloyloxy)propyltrimethoxysilane was 3.2 g:200 mL:0.04 g:25 mL:9.7 g. S7. Mix the polyphosphazene microspheres, modified polymethyl hydrogen siloxane and toluene, stir ultrasonically for 40 minutes, filter, wash the solid phase, and vacuum dry to obtain the flame retardant; the dosage ratio of the polyphosphazene microspheres, modified polymethyl hydrogen siloxane and toluene is 2.3g:5.8g:100mL.

[0021] Example 2 A method for preparing a flame retardant and fireproof cable comprises the following steps: The cable core material obtained by twisting the copper wires and the sheath material are uniformly mixed and heated to 180°C, and then extruded through a twin-screw extruder and wrapped on the surface of the cable core material to form a sheath layer, thereby obtaining a flame retardant and fireproof cable; The sheath material includes 45 parts by mass of high-density polyethylene, 20 parts by mass of linear low-density polyethylene, 50 parts by mass of ethylene-vinyl acetate copolymer, 1.5 parts by mass of antioxidant 1010, 6 parts by mass of flame retardant, 1.5 parts by mass of calcium stearate, 1.5 parts by mass of stearic acid, 8 parts by mass of polyethylene wax, 9 parts by mass of maleic anhydride grafted polyethylene, and 2.5 parts by mass of diisostyrene peroxide; The preparation method of the flame retardant comprises the following steps: S1. Mix dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and triethylamine, stir for 35 minutes, add N-hydroxyethyl acrylamide, add carbon tetrachloride dropwise in an ice-water bath, and react at room temperature for 12 hours. After the reaction, the product is diluted with dichloromethane, extracted with a saturated sodium chloride solution, and the organic layer is dehydrated and then distilled under reduced pressure. The product is purified using a developing agent prepared by petroleum ether and ethyl acetate in a volume ratio of 1:10, and then the solvent is removed by distillation under reduced pressure to obtain a nitrogen-phosphorus DOPO derivative; the ratio of dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triethylamine, N-hydroxyethyl acrylamide, and carbon tetrachloride is 250 mL:22 g:3.0 g:14 mL:12.6 mL; S2. Hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate were mixed, refluxed and stirred at 85° C. for 4 h, transferred to a polytetrafluoroethylene autoclave, and hydrothermally reacted at 100° C. for 24 h, washed, centrifuged, and dried to obtain hexamethylenediaminetetramethylenephosphonic acid cobalt; the ratio of hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate was 9 g:200 mL:16.5 g; S3. Phenylphosphonic acid, deionized water, and lanthanum nitrate hexahydrate were mixed, refluxed and stirred at 85° C. for 4 h, transferred to a polytetrafluoroethylene autoclave, and subjected to a hydrothermal reaction at 100° C. for 24 h. The mixture was washed, centrifuged, and dried to obtain lanthanum phenylphosphonate; the ratio of phenylphosphonic acid, deionized water, and lanthanum nitrate hexahydrate was 9 g:200 mL:8.9 g. S4. Take the nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, and anhydrous ethanol, mix them, ultrasonically stir for 15 minutes, add calcium chloride solution, stir at 45°C for 1.5 hours, then add sodium carbonate solution and continue stirring for 1.5 hours, collect the precipitate by centrifugation, wash, and dry at 60°C for 7 hours to obtain a nano-calcium carbonate embedding material; the dosage ratio of the nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, anhydrous ethanol, calcium chloride solution, and sodium carbonate solution is 2.3g:0.7g:0.25g:0.17g:50mL:250mL:500mL; the concentration of the calcium chloride solution is 1mol / L; the concentration of the sodium carbonate solution is 1mol / L; S5. Mix 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, and nano-calcium carbonate embedding material, ultrasonically disperse for 35 minutes, add hexachlorocyclotriphosphazene, stir at 45°C for 8 hours, centrifuge, wash the solid phase, and vacuum dry to obtain polyphosphazene microspheres; the ratio of 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, nano-calcium carbonate embedding material, and hexachlorocyclotriphosphazene is 1.35 g:100 mL:3.5 mL:2.5 g:1.1 g; S6. In a nitrogen atmosphere, polymethyl hydrogen siloxane and toluene were mixed, an ethanol solution of chloroplatinic acid was added, and the mixture was stirred at 70° C. for 35 min. The mixture was heated to 93° C., γ-(methacryloyloxy)propyltrimethoxysilane was added, and the mixture was refluxed and stirred for 5 h. The mixture was purified by vacuum distillation to obtain modified polymethyl hydrogen siloxane; the ratio of the polymethyl hydrogen siloxane, toluene, chloroplatinic acid, anhydrous ethanol, and γ-(methacryloyloxy)propyltrimethoxysilane was 3.8 g:200 mL:0.05 g:25 mL:10.5 g. S7. Mix the polyphosphazene microspheres, modified polymethyl hydrogen siloxane and toluene, stir ultrasonically for 50 minutes, filter, wash the solid phase, and vacuum dry to obtain the flame retardant; the dosage ratio of the polyphosphazene microspheres, modified polymethyl hydrogen siloxane and toluene is 2.8g:6.5g:100mL.

[0022] Example 3 A method for preparing a flame retardant and fireproof cable comprises the following steps: The cable core material obtained by twisting the copper wires and the sheath material are uniformly mixed and heated to 190°C, and then extruded through a twin-screw extruder and wrapped on the surface of the cable core material to form a sheath layer, thereby obtaining a flame retardant and fireproof cable; The sheath material includes 50 parts by mass of high-density polyethylene, 25 parts by mass of linear low-density polyethylene, 55 parts by mass of ethylene-vinyl acetate copolymer, 2 parts by mass of antioxidant 1010, 7 parts by mass of flame retardant, 2 parts by mass of calcium stearate, 2 parts by mass of stearic acid, 9 parts by mass of polyethylene wax, 10 parts by mass of maleic anhydride grafted polyethylene, and 3 parts by mass of diisostyrene peroxide; The preparation method of the flame retardant comprises the following steps: S1. Mix dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and triethylamine, stir for 40 minutes, add N-hydroxyethyl acrylamide, add carbon tetrachloride dropwise in an ice-water bath, and react at room temperature for 15 hours. After the reaction, the product is diluted with dichloromethane, extracted with a saturated sodium chloride solution, and the organic layer is dehydrated and then distilled under reduced pressure. The product is purified using a developing agent prepared by petroleum ether and ethyl acetate in a volume ratio of 1:10, and then the solvent is removed by distillation under reduced pressure to obtain a nitrogen-phosphorus DOPO derivative; the ratio of dichloromethane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, triethylamine, N-hydroxyethyl acrylamide, and carbon tetrachloride is 300 mL:25 g:3.6 g:16 mL:13.8 mL; S2. Hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate were mixed, refluxed and stirred at 90° C. for 5 h, transferred to a polytetrafluoroethylene autoclave, and hydrothermally reacted at 100° C. for 24 h, washed, centrifuged, and dried to obtain hexamethylenediaminetetramethylenephosphonic acid cobalt; the ratio of hexamethylenediaminetetramethylenephosphonic acid, deionized water, and cobalt nitrate hexahydrate was 10 g:200 mL:17.4 g; S3. Phenylphosphonic acid, deionized water, and lanthanum nitrate hexahydrate were mixed, refluxed and stirred at 90° C. for 5 h, transferred to a polytetrafluoroethylene autoclave, and subjected to a hydrothermal reaction at 100° C. for 24 h. The mixture was washed, centrifuged, and dried to obtain lanthanum phenylphosphonate; the ratio of phenylphosphonic acid, deionized water, and lanthanum nitrate hexahydrate was 10 g:200 mL:10.2 g. S4. The nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, and anhydrous ethanol are mixed, ultrasonically stirred for 20 minutes, a calcium chloride solution is added, and the mixture is stirred at 50° C. for 2 hours. Then, a sodium carbonate solution is added and the mixture is stirred for 2 hours. The precipitate is collected by centrifugation, washed, and dried at 60° C. for 8 hours to obtain a nano-calcium carbonate embedding material; the amount ratio of the nitrogen-phosphorus DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt, lanthanum phenylphosphonate, sodium dodecylbenzenesulfonate, anhydrous ethanol, calcium chloride solution, and sodium carbonate solution is 2.8 g: 0.8 g: 0.3 g: 0.23 g: 50 mL: 250 mL: 500 mL; the concentration of the calcium chloride solution is 1 mol / L; the concentration of the sodium carbonate solution is 1 mol / L; S5. Mix 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, and nano-calcium carbonate embedding material, ultrasonically disperse for 40 minutes, add hexachlorocyclotriphosphazene, stir at 45°C for 9 hours, centrifuge, wash the solid phase, and vacuum dry to obtain polyphosphazene microspheres; the ratio of 4,4'-dihydroxydiphenyl sulfone, acetonitrile, triethylamine, nano-calcium carbonate embedding material, and hexachlorocyclotriphosphazene is 1.5 g:100 mL:4 mL:2.8 g:1.2 g; S6. In a nitrogen atmosphere, polymethyl hydrogen siloxane and toluene were mixed, an ethanol solution of chloroplatinic acid was added, and the mixture was stirred at 75° C. for 40 min. The mixture was heated to 95° C., γ-(methacryloyloxy)propyltrimethoxysilane was added, and the mixture was refluxed with stirring for 6 h. The mixture was purified by distillation under reduced pressure to obtain modified polymethyl hydrogen siloxane; the ratio of the polymethyl hydrogen siloxane, toluene, chloroplatinic acid, anhydrous ethanol, and γ-(methacryloyloxy)propyltrimethoxysilane was 4.4 g:200 mL:0.06 g:25 mL:11.3 g. S7. Mix the polyphosphazene microspheres, modified polymethyl hydrogen siloxane and toluene, stir ultrasonically for 60 minutes, filter, wash the solid phase, and vacuum dry to obtain the flame retardant; the dosage ratio of the polyphosphazene microspheres, modified polymethyl hydrogen siloxane and toluene is 3.4g:7.2g:100mL.

[0023] Comparative Example 1 The difference from Example 2 is that the contents of the nano-calcium carbonate embedding material only contain nitrogen-phosphorus-containing DOPO derivatives and cobalt hexamethylenediaminetetramethylenephosphonate.

[0024] Comparative Example 2 The difference from Example 2 is that the contents of the nano-calcium carbonate embedding material only contain nitrogen-phosphorus-containing DOPO derivatives and lanthanum phenylphosphonate.

[0025] Comparative Example 3 The difference from Example 2 is that the flame retardant is only the nano-calcium carbonate embedding material prepared in steps S1 to S4.

[0026] Comparative Example 4 The difference from Example 2 is that the flame retardant is only the polyphosphazene microspheres prepared in steps S1 to S5.

[0027] Performance Testing The cables prepared in each embodiment and comparative example were subjected to performance tests: the mechanical properties of the cables were tested in accordance with standard GB / T 2951.11-2008; the flame retardant properties of the cables were evaluated in accordance with standard IEC 60332, and a vertical burning test was performed; the limiting oxygen index was tested in accordance with GB / T 2406.2-2009; the test results are shown in Table 1 below.

[0028] Table 1 As can be seen from Table 1, the cables prepared in Examples 1 to 3 of the present application have good flame retardant and fireproof properties and flexibility; Comparative Examples 1 and 2 lack the synergistic flame retardant effect of nitrogen-phosphorus DOPO derivatives, cobalt hexamethylenediaminetetramethylenephosphonate and lanthanum phenylphosphonate, resulting in a decrease in the flame retardant effect of the cable, but almost no effect on the flexibility of the cable; in Comparative Example 3, only nano-calcium carbonate embedding material is added, resulting in a significant decrease in the flexibility and flame retardant properties of the cable; in Comparative Example 4, the polyphosphazene microspheres are not subjected to silicone surface treatment, resulting in a significant decrease in the flexibility of the cable and a decrease in the flame retardant effect.

[0029] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a flame-retardant and fire-resistant cable, wherein the flame-retardant and fire-resistant cable comprises a cable core material obtained by twisting copper wires, and a sheath layer wrapped around the surface of the cable core material, characterized in that: The method for preparing the flame retardant and fireproof cable comprises the following steps: High-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant, flame retardant, calcium stearate, stearic acid, polyethylene wax, compatibilizer, and cross-linking agent are uniformly mixed and heated to 170-190° C., and then extruded through a twin-screw extruder and wrapped on the surface of the cable core material to form a sheath layer, thereby obtaining the flame-retardant and fire-resistant cable; The flame retardant is polymethylhydrogensiloxane modified with γ-(methacryloyloxy)propyltrimethoxysilane grafted onto polyphosphazene microspheres; The polyphosphazene microspheres are coated with nano-calcium carbonate embeddings; The contents of the nano calcium carbonate embedding material include nitrogen-phosphorus-containing DOPO derivatives, hexamethylenediaminetetramethylenephosphonic acid cobalt and phenylphosphonic acid lanthanum.

2. The method for preparing a flame retardant and fireproof cable according to claim 1, characterized in that: The mass ratio of the high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant, flame retardant, calcium stearate, stearic acid, polyethylene wax, compatibilizer and cross-linking agent is 40-50:15-25:45-55:1-2:5-7:1-2:1-2:7-9:8-10:2-3.

3. The method for preparing a flame retardant and fireproof cable according to claim 1, characterized in that: The mass ratio of the nitrogen-phosphorus-containing DOPO derivative, hexamethylenediaminetetramethylenephosphonic acid cobalt and phenylphosphonic acid lanthanum is 1.8-2.8:0.6-0.8:0.2-0.

3.

4. The method for preparing a flame retardant and fireproof cable according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polyethylene.

5. The method for preparing a flame retardant and fireproof cable according to claim 1, characterized in that: The cross-linking agent is diisophenylpropene peroxide.

6. The method for preparing a flame retardant and fireproof cable according to claim 1, characterized in that: The antioxidant is antioxidant 1010.

7. A flame retardant and fireproof cable prepared according to the preparation method according to any one of claims 1 to 6.

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