Fire resistant cable and method of making the same

Abstract

The application discloses a fire-resistant cable and a preparation method thereof, and relates to the technical field of cables.The preparation method is as follows: copper wires are twisted to form a conductor, a layer of phlogopite tape is wound on the surface of the conductor, a layer of insulating material is extruded on the surface and solidified to obtain an insulating core; 4-6 insulating cores are twisted together to form a cable core, polypropylene ropes are filled in the gaps between the cable cores, the cable core is fixed by winding with a binding tape, a layer of sheath material is extruded on the outer surface and solidified to obtain the fire-resistant cable.The insulating material is prepared from epoxy resin E51, a synergist, modified basalt and amine benzene sulfone; and the sheath material is prepared from carbon fiber short-cut filaments, modified basalt, curing agent T31, modified powder and epoxy resin E51.The introduction of the synergist, modified basalt and modified powder effectively improves the wear resistance, fire resistance and high-temperature resistance of the fire-resistant cable.Therefore, the application has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and more specifically to a fire-resistant cable and its preparation method. Background Technology

[0002] A cable is an electrical device used to transmit electrical energy, electrical signals, and realize electromagnetic energy conversion. It consists of four parts: a conductor, an insulation layer, a shielding layer, and a sheath. The conductor, usually made of a highly conductive metal, carries current and transmits electrical energy or signals. The insulation layer, made of a highly insulating material, surrounds the conductor to prevent current leakage and short circuits between conductors, ensuring safe and stable power transmission. The shielding layer, generally made of metal, primarily reduces interference from the cable's internal electromagnetic field to the outside world, while also preventing external electromagnetic fields from affecting the internal signals, ensuring signal transmission quality. The sheath layer, the outermost layer of the cable, mainly provides protection. Cables are widely used in the power industry, industrial sectors, construction industry, and communications industry; therefore, the demand for cables is increasing, and performance requirements are becoming more stringent. For example, the power supply lines for fire pumps, smoke exhaust fans, and fire alarm controllers need to have excellent fire resistance.

[0003] However, in practical applications, the fire resistance time of cables is still relatively short, which cannot meet the requirements for long-term normal operation during a fire, thus limiting their application. Therefore, the fire resistance and high-temperature performance stability of existing cables still need to be further improved. Summary of the Invention

[0004] The purpose of this invention is to provide a fire-resistant cable and its preparation method, thereby solving the following technical problems:

[0005] Existing cables still suffer from poor fire resistance and performance stability at high temperatures.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a fire-resistant cable includes the following steps:

[0008] S1: Twist 2-10 copper wires with a diameter of 0.5-5mm together to form a conductor, then wrap a layer of phlogopite tape around the surface of the conductor, and then use an extruder to extrude a layer of insulating material on its surface and cure it to form an insulating layer with a thickness of 0.5-2.5mm, thus obtaining an insulated wire core.

[0009] S2: Twist 4-6 insulated wire cores together to form a cable core, fill the gaps between the cable cores with polypropylene rope, then wrap and fix it with binding tape, then extrude a layer of sheath material on the outer surface and perform secondary curing to form a 1-3mm thick sheath layer, thus obtaining a fire-resistant cable.

[0010] The insulating material comprises the following raw materials in parts by weight: 200-250 parts of epoxy resin E51, 10-12 parts of synergist, 20-25 parts of modified basalt, and 92-112 parts of sulfamic acid.

[0011] The sheath material comprises the following raw materials in parts by weight: 5-7 parts of chopped carbon fiber filaments, 35-45 parts of modified basalt, 18-20 parts of curing agent T31, 10-12 parts of modified powder, and 100-150 parts of epoxy resin E51.

[0012] The synergist was prepared by reacting phenylphosphonic dichloride with anhydrous piperazine in the presence of triethylamine;

[0013] The modified basalt is basalt that has been pretreated with sodium hydroxide aqueous solution, grafted with silane coupling agent KH550, and then modified with sodium phytate and nickel acetate.

[0014] The modified powder is a mixed powder obtained by reacting magnesium nitrate and aluminum nitrate, which is first grafted with silane coupling agent KH-550, and then grafted with a polymer of hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone.

[0015] Preferably, the method for preparing the insulating material is as follows:

[0016] Add synergists to epoxy resin E51 at 68-72℃ and stir well. Then add modified basalt and stir well. Then add sulfone aminophenylene at 115-125℃ and mix for 5-7 minutes. After degassing under vacuum, extrude and granulate to obtain the insulating material.

[0017] Preferably, the sheath material is prepared by the following method:

[0018] Carbon fiber short filaments, modified basalt, curing agent T31, and modified powder are mixed evenly. Then, epoxy resin E51 is added and stirred at 800-1000 r / min for 30-50 min. After degassing under vacuum for 30-60 min, the mixture is extruded and granulated to obtain the sheath material.

[0019] Preferably, the curing process is as follows: first, curing at 150-160℃ and 1MPa for 1.5-2 hours, then curing at 190-210℃ and 10MPa for 2-3 hours, and finally curing at 225-235℃ and 10MPa for 2-3 hours;

[0020] The secondary curing process involves curing at 125-135℃ and 8-10MPa for 30-40 minutes.

[0021] Preferably, the synergist is prepared by the following method:

[0022] A1: Dissolve phenylphosphonic dichloride in N,N-dimethylformamide to obtain a phenylphosphonic dichloride solution;

[0023] A2: Add anhydrous piperazine and triethylamine to N,N-dimethylformamide and stir at 1-10℃ for 30-40 min. Then, add phenylphosphonic dichloride solution dropwise at 0.5 g / min and stir at 1-10℃ for 2-3 h, then at 25-35℃ for 10-15 h. Finally, reflux at 75-100℃ for 10-12 h, cool, filter, and wash the filter cake 5-7 times with chloroform. Vacuum dry at 75-80℃ for 10-15 h to obtain the synergist.

[0024] Preferably, the mass ratio of phenylphosphonic dichloro to N,N-dimethylformamide in A1 is 10-12:20-24;

[0025] The mass ratio of N,N-dimethylformamide, anhydrous piperazine, triethylamine, and phenylphosphonic dichloride solution in A2 is 60-72:8.6-10.3:10.2-12.2:30-36.

[0026] Preferably, the modified basalt is prepared by the following method:

[0027] B1: Add basalt to an aqueous sodium hydroxide solution and stir at 98-100℃ for 2-3 hours. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 105-110℃ for 20-30 hours to obtain pretreated basalt.

[0028] B2: Add pretreated basalt, silane coupling agent KH550, and glacial acetic acid to deionized water and stir at 75-80℃ for 3-4 hours. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 105-110℃ for 20-30 hours to obtain grafted basalt.

[0029] B3: Add grafted basalt and sodium phytate to deionized water and stir at 75-80℃ for 1-1.5h. Then add nickel acetate and stir at 75-80℃ for 2-3h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 105-110℃ for 20-30h to obtain modified basalt.

[0030] Preferably, the mass ratio of the sodium hydroxide aqueous solution to basalt in B1 is 900-1000:60-70;

[0031] The concentration of the sodium hydroxide aqueous solution described in B1 is 4 mol / L;

[0032] The mass ratio of deionized water, pretreated basalt, silane coupling agent KH550, and glacial acetic acid in B2 is 800-1000:60-70:2-3.5:0.5-1;

[0033] The mass ratio of deionized water, grafted basalt, sodium phytate, and nickel acetate described in B3 is 1500-2500:60-70:108-156:63-87.

[0034] Preferably, the modified powder is prepared by the following method:

[0035] C1: Add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to deionized water and stir well to obtain a mixed solution;

[0036] C2: Add sodium hydroxide and sodium carbonate to deionized water and stir well. Deoxygenate with nitrogen gas at a flow rate of 100 mL / min for 20-30 min, then add the mixture dropwise at a flow rate of 1 mL / min. Stir at 68-70℃ under a nitrogen atmosphere for 18-20 h. After cooling, centrifuge and wash the precipitate with deionized water 5-6 times. Finally, vacuum dry at 55-60℃ for 10-15 h, grind and pass through a 200-mesh sieve to obtain the mixed powder.

[0037] C3: Add the mixed powder to anhydrous ethanol and sonicate for 15-25 min. Then add the ethanol solution of silane coupling agent KH-550 dropwise and stir at 45-50℃ for 3-4 h. Then centrifuge and wash the precipitate with anhydrous ethanol 3-5 times. Finally, vacuum dry at 55-60℃ for 8-10 h, grind and pass through a 200-mesh sieve to obtain the grafted powder.

[0038] C4: Add the grafted powder to anhydrous acetonitrile and sonicate for 20-30 min. After deoxygenating with nitrogen at a flow rate of 100 mL / min for 20-30 min, add hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone sequentially at 0-5℃ and stir for 10-20 min. Then, add triethylamine dropwise and stir at 0-5℃ for 1-2.5 h. Then, stir at 65-70℃ for 18-20 h. After cooling, centrifuge and wash 3-5 times with anhydrous acetonitrile, 2-4 times with deionized water, and once with anhydrous ethanol. Finally, vacuum dry at 65-70℃ for 10-15 h, grind, and pass through a 100-mesh sieve to obtain the modified powder.

[0039] Preferably, the mass ratio of deionized water, magnesium nitrate hexahydrate, and aluminum nitrate nonahydrate in C1 is 200-250: 20.6-24.7: 9.4-11.3;

[0040] The mass ratio of deionized water, sodium hydroxide, sodium carbonate, and the mixed solution described in C2 is 200-250: 8.8-10.6: 1.3-1.6: 230-286;

[0041] The mass ratio of anhydrous ethanol, mixed powder, and silane coupling agent KH-550 in the ethanol solution described in C3 is 200-240:10-12:10-12;

[0042] The ethanol solution of the silane coupling agent KH-550 described in C3 has a mass fraction of 3%;

[0043] The mass ratio of anhydrous acetonitrile, grafted powder, hexachlorocyclotriphosphazene, 4,4'-dihydroxydiphenyl sulfone, and triethylamine in C4 is 200-240:10-12:12.5-15:31-37.2:11-13.

[0044] The beneficial effects of this invention are:

[0045] This invention provides a fire-resistant cable and its preparation method. The invention effectively improves the fire resistance and high-temperature performance stability of the cable through the following method.

[0046] (1) The modified basalt of this invention has high hardness. After etching with sodium hydroxide, a rough structure is formed on the surface. Combined with KH550 grafting, the interfacial compatibility with the resin is improved. It can resist friction and wear through "rigid support" and reduce material surface peeling. Sodium phytate and nickel acetate form a phosphorus-nickel synergistic flame retardant system. Phosphorus can promote char formation to form a heat insulation layer, and nickel acts as a catalyst to enhance the stability of the char layer and inhibit flame propagation. Basalt can support the material morphology at high temperature. Phosphate esters generated by the high-temperature decomposition of sodium phytate can form a glassy flame retardant coating, delaying heat transfer and resin degradation, and extending the fire resistance time. KH550 grafting enables chemical bonding between basalt and resin, reducing interfacial defects. Rigid basalt particles can disperse external loads, inhibit crack propagation, and improve tensile strength. The inorganic skeleton of basalt and the stable char layer formed by the phosphorus-nickel system can reduce the rate of thermal oxidation decomposition of resin, thereby increasing the proportion of strength retained by the material at high temperature.

[0047] (2) In the synergist molecule of the present invention, the phosphorus element reacts at high temperature to generate a viscous protective layer such as phosphate ester, which isolates oxygen and heat; the inert gas released by the nitrogen element dilutes the combustible gas, and the two work together to play a flame-retardant role. At high temperature, the synergist decomposes to form a stable and dense phosphorus-nitrogen composite carbonized layer, which hinders the flame from eroding the substrate and transferring heat, delays the thermal oxidative degradation of epoxy resin, and prolongs the fire resistance time.

[0048] (3) The layered double hydroxide lamellar structure in the modified powder of this invention has a rigidity-enhancing effect, the cross-linking network of polyphosphazene can improve the material hardness, and the silane coupling agent improves the interfacial bonding force between the powder and epoxy resin, reducing filler shedding during wear. The layered double hydroxide decomposes at high temperature, absorbing heat and releasing inert gases such as carbon dioxide. When polyphosphazene burns, it forms a phosphorus-based flame-retardant coating. The two can work together to exert a flame-retardant effect. The layered double hydroxide lamellars form a physical barrier layer at high temperature, slowing down heat transfer; the glassy phosphorus oxide coating generated by the decomposition of polyphosphazene can isolate oxygen and protect the substrate from rapid oxidation. The inorganic rigid skeleton and organic cross-linking structure of the modified powder can disperse stress and improve tensile strength. Both the layered double hydroxide and polyphosphazene have excellent high-temperature stability and can inhibit the thermal degradation and softening of epoxy resin at high temperatures.

[0049] Therefore, the fire-resistant cable prepared by this invention has excellent wear resistance, fire resistance and high temperature resistance, as well as a wider range of application prospects. Detailed Implementation

[0050] 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.

[0051] Example 1: A method for preparing a fire-resistant cable is as follows:

[0052] S1: Add 60g of basalt to 900g of sodium hydroxide aqueous solution with a concentration of 4mol / L and stir at 98℃ for 2h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 105℃ for 20h to obtain pretreated basalt.

[0053] S2: Add 60g of pretreated basalt, 2g of silane coupling agent KH550 and 0.5g of glacial acetic acid to 800mL of deionized water and stir at 75℃ for 3h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 105℃ for 20h to obtain grafted basalt.

[0054] S3: Add 60g of grafted basalt and 108g of sodium phytate to 1500mL of deionized water and stir at 75℃ for 1h. Then add 63g of nickel acetate and stir at 75℃ for 2h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 105℃ for 20h to obtain modified basalt.

[0055] S4: Dissolve 10g of phenylphosphonic dichloride in 20g of N,N-dimethylformamide to obtain a phenylphosphonic dichloride solution;

[0056] S5: Add 8.6g of anhydrous piperazine and 10.2g of triethylamine to 60g of N,N-dimethylformamide and stir at 1℃ for 30min. Then, add 30g of phenylphosphonic dichloride solution dropwise at 0.5g / min and stir at 1℃ for 2h, then at 25℃ for 10h, and finally reflux at 75℃ for 10h. After cooling, filter and wash the filter cake 5 times with chloroform. Dry under vacuum at 75℃ for 10h to obtain the synergist.

[0057] S6: Add 10g of synergist to 200g of epoxy resin E51 at 68℃ and stir for 20min. Then add 20g of modified basalt and stir for 20min. Then add 92g of aminophenyl sulfone at 115℃ and mix at 800r / min for 5min. After degassing under vacuum for 30min, extrude and granulate to obtain the insulating material.

[0058] S7: Add 20.6g magnesium nitrate hexahydrate and 9.4g aluminum nitrate nonahydrate to 200g deionized water and stir for 20min to obtain a mixed solution;

[0059] S8: Add 8.8g sodium hydroxide and 1.3g sodium carbonate to 200g deionized water and stir for 20min. After deoxygenating with nitrogen at a flow rate of 100mL / min for 20min, add 230g of the mixed solution dropwise at a flow rate of 1mL / min. Then stir for 18h under a nitrogen atmosphere at 68℃. After cooling, centrifuge and wash the precipitate 5 times with deionized water. Finally, vacuum dry at 55℃ for 10h, grind and pass through a 200-mesh sieve to obtain the mixed powder.

[0060] S9: Add 10g of mixed powder to 200g of anhydrous ethanol and sonicate for 15min. Then add 10g of ethanol solution of 3% KH-550 silane coupling agent and stir at 45℃ for 3h. Then centrifuge and wash the precipitate three times with anhydrous ethanol. Finally, vacuum dry at 55℃ for 8h, grind and pass through a 200-mesh sieve to obtain the grafted powder.

[0061] S10: Add 10g of grafted powder to 200g of anhydrous acetonitrile and sonicate for 20min. After deoxygenating with nitrogen at a flow rate of 100mL / min for 20min, add 12.5g of hexachlorocyclotriphosphazene and 31g of 4,4'-dihydroxydiphenyl sulfone sequentially at 0℃ and stir for 10min. Then add 11g of triethylamine dropwise and stir at 0℃ for 1h. Then stir at 65℃ for 18h. After cooling, centrifuge and wash three times with anhydrous acetonitrile, twice with deionized water, and once with anhydrous ethanol. Finally, vacuum dry at 65℃ for 10h, grind, and pass through a 100-mesh sieve to obtain modified powder.

[0062] S11: Mix 5g of carbon fiber short filaments, 35g of modified basalt, 18g of curing agent T31 and 10g of modified powder evenly, then add 100g of epoxy resin E51 and stir at 800r / min for 30min. After degassing under vacuum for 30min, extrude and granulate to obtain the sheath material.

[0063] S12: Two copper wires with a diameter of 0.5mm are twisted together to form a conductor;

[0064] S13: A layer of phlogopite tape is wound around the surface of the conductor, and then an insulating material is extruded onto the surface using an extruder and cured to form a 0.5mm thick insulating layer, thus obtaining an insulated wire core; wherein, the curing treatment is as follows: first, it is cured at 150℃ and 1MPa for 1.5h, then cured at 190℃ and 10MPa for 2h, and finally cured at 225℃ and 10MPa for 2h.

[0065] S14: Four insulated wire cores are twisted together to form a cable core, and polypropylene rope is filled between the cable cores. Then, the cores are wrapped and fixed with binding tape. A layer of sheath material is then extruded onto the outer surface and cured at 125℃ and 8MPa for 30 minutes to form a 1mm thick sheath layer, thus obtaining a fire-resistant cable.

[0066] Example 2: A method for preparing a fire-resistant cable is as follows:

[0067] S1: Add 65g of basalt to 950g of 4mol / L sodium hydroxide aqueous solution and stir at 99℃ for 2.5 seconds. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 108℃ for 25 hours to obtain pretreated basalt.

[0068] S2: Add 65g of pretreated basalt, 2.8g of silane coupling agent KH550 and 0.8g of glacial acetic acid to 900mL of deionized water and stir at 78℃ for 3.5h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 108℃ for 25h to obtain grafted basalt.

[0069] S3: Add 65g of grafted basalt and 132g of sodium phytate to 2000mL of deionized water and stir at 78℃ for 1.2h. Then add 75g of nickel acetate and stir at 78℃ for 2.5h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 108℃ for 25h to obtain modified basalt.

[0070] S4: Dissolve 11g of phenylphosphonic dichloride in 22g of N,N-dimethylformamide to obtain a phenylphosphonic dichloride solution;

[0071] S5: Add 9.4g of anhydrous piperazine and 11.2g of triethylamine to 66g of N,N-dimethylformamide and stir at 5℃ for 35min. Then, add 33g of phenylphosphonic dichloride solution dropwise at 0.5g / min and stir at 5℃ for 2.5h, then at 30℃ for 13h, and finally reflux at 85℃ for 11h. After cooling, filter and wash the filter cake 6 times with chloroform. Dry under vacuum at 78℃ for 13h to obtain the synergist.

[0072] S6: Add 11g of synergist to 225g of epoxy resin E51 at 70℃ and stir for 30min. Then add 22.5g of modified basalt and stir for 30min. Then add 102g of aminophenyl sulfone at 120℃ and mix at 850r / min for 6min. After degassing under vacuum for 45min, extrude and granulate to obtain the insulating material.

[0073] S7: Add 22.7g magnesium nitrate hexahydrate and 10.3g aluminum nitrate nonahydrate to 225g deionized water and stir for 25min to obtain a mixed solution;

[0074] S8: Add 9.7g sodium hydroxide and 1.45g sodium carbonate to 252g deionized water and stir for 25min. After deoxygenating with nitrogen at a flow rate of 100mL / min for 25min, add 258g of the mixed solution dropwise at a flow rate of 1mL / min. Then stir for 19h under a nitrogen atmosphere at 69℃. After cooling, centrifuge and wash the precipitate 6 times with deionized water. Finally, vacuum dry at 58℃ for 13h, grind and pass through a 200-mesh sieve to obtain the mixed powder.

[0075] S9: Add 11g of mixed powder to 220g of anhydrous ethanol and sonicate for 20min. Then add 11g of 3% KH-550 ethanol solution of silane coupling agent and stir at 48℃ for 3.5h. Then centrifuge and wash the precipitate 4 times with anhydrous ethanol. Finally, vacuum dry at 58℃ for 9h, grind and pass through a 200-mesh sieve to obtain the grafted powder.

[0076] S10: 11g of grafted powder was added to 220g of anhydrous acetonitrile and sonicated for 25min. After deoxygenation with nitrogen at a flow rate of 100mL / min for 25min, 13.7g of hexachlorocyclotriphosphazene and 34.1g of 4,4'-dihydroxydiphenyl sulfone were added sequentially at 3℃ and stirred for 15min. Then, 12g of triethylamine was added dropwise and stirred at 3℃ for 1.7h. Then, the mixture was stirred at 68℃ for 19h. After cooling, the mixture was centrifuged and washed 4 times with anhydrous acetonitrile, 3 times with deionized water, and 1 time with anhydrous ethanol. Finally, the mixture was vacuum dried at 68℃ for 13h, ground, and passed through a 100-mesh sieve to obtain the modified powder.

[0077] S11: Mix 6g of carbon fiber short filaments, 40g of modified basalt, 19g of curing agent T31 and 11g of modified powder evenly, then add 125g of epoxy resin E51 and stir at 900r / min for 40min. After degassing under vacuum for 45min, extrude and granulate to obtain the sheath material.

[0078] S12: Six copper wires with a diameter of 3mm are twisted together to form a conductor;

[0079] S13: A layer of phlogopite tape is wound around the surface of the conductor, and then an insulating material is extruded onto the surface using an extruder and cured to form a 1.5mm thick insulating layer, thus obtaining an insulated wire core; wherein, the curing treatment is as follows: first, it is cured at 155℃ and 1MPa for 1.8h, then cured at 200℃ and 10MPa for 2.5h, and finally cured at 230℃ and 10MPa for 2.5h.

[0080] S14: Five insulated wire cores are twisted together to form a cable core, and polypropylene rope is filled between the cable cores. Then, the cores are wrapped and fixed with binding tape. A layer of sheath material is then extruded onto the outer surface and cured at 130℃ and 9MPa for 35 minutes to form a 2mm thick sheath layer, thus obtaining a fire-resistant cable.

[0081] Example 3: A method for preparing a fire-resistant cable is as follows:

[0082] S1: Add 70g of basalt to 1000g of sodium hydroxide aqueous solution with a concentration of 4mol / L and stir at 100℃ for 3h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 110℃ for 30h to obtain pretreated basalt.

[0083] S2: Add 70g of pretreated basalt, 3.5g of silane coupling agent KH550 and 1g of glacial acetic acid to 1000mL of deionized water and stir at 80℃ for 4h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 110℃ for 30h to obtain grafted basalt.

[0084] S3: Add 70g of grafted basalt and 156g of sodium phytate to 2500mL of deionized water and stir at 80℃ for 1.5h. Then add 87g of nickel acetate and stir at 80℃ for 3h. Then centrifuge and wash the precipitate with deionized water until the pH is 7. Finally, dry at 110℃ for 30h to obtain modified basalt.

[0085] S4: Dissolve 12g of phenylphosphonic dichloride in 24g of N,N-dimethylformamide to obtain a phenylphosphonic dichloride solution;

[0086] S5: Add 10.3g of anhydrous piperazine and 12.2g of triethylamine to 72g of N,N-dimethylformamide and stir at 10℃ for 40min. Then, add 36g of phenylphosphonic dichloride solution dropwise at 0.5g / min and stir at 10℃ for 3h, then at 35℃ for 15h, and finally reflux at 100℃ for 12h. After cooling, filter and wash the filter cake 7 times with chloroform. Dry under vacuum at 80℃ for 15h to obtain the synergist.

[0087] S6: Add 12g of synergist to 250g of epoxy resin E51 at 72℃ and stir for 40min. Then add 25g of modified basalt and stir for 40min. Then add 112g of aminophenyl sulfone at 125℃ and mix at 900r / min for 7min. After degassing under vacuum for 60min, extrude and granulate to obtain the insulating material.

[0088] S7: Add 24.7g magnesium nitrate hexahydrate and 11.3g aluminum nitrate nonahydrate to 250g deionized water and stir for 30min to obtain a mixed solution;

[0089] S8: Add 10.6g sodium hydroxide and 1.6g sodium carbonate to 250g deionized water and stir for 30min. After deoxygenating with nitrogen at a flow rate of 100mL / min for 30min, add 286g of the mixed solution dropwise at a flow rate of 1mL / min. Then stir at 70℃ under a nitrogen atmosphere for 20h. After cooling, centrifuge and wash the precipitate 6 times with deionized water. Finally, vacuum dry at 60℃ for 15h, grind and pass through a 200-mesh sieve to obtain the mixed powder.

[0090] S9: Add 12g of mixed powder to 240g of anhydrous ethanol and sonicate for 25min. Then add 12g of ethanol solution of 3% KH-550 silane coupling agent and stir at 50℃ for 4h. Then centrifuge and wash the precipitate 5 times with anhydrous ethanol. Finally, vacuum dry at 60℃ for 10h, grind and pass through a 200-mesh sieve to obtain the grafted powder.

[0091] S10: 12g of grafted powder was added to 240g of anhydrous acetonitrile and sonicated for 30min. After deoxygenation with nitrogen at a flow rate of 100mL / min for 30min, 15g of hexachlorocyclotriphosphazene and 37.2g of 4,4'-dihydroxydiphenyl sulfone were added sequentially at 5℃ and stirred for 20min. Then, 13g of triethylamine was added dropwise and stirred at 5℃ for 2.5h. Then, the mixture was stirred at 70℃ for 20h. After cooling, the mixture was centrifuged and washed 5 times with anhydrous acetonitrile, 4 times with deionized water, and once with anhydrous ethanol. Finally, the mixture was vacuum dried at 70℃ for 15h, ground, and passed through a 100-mesh sieve to obtain the modified powder.

[0092] S11: Mix 7g of carbon fiber short filaments, 45g of modified basalt, 20g of curing agent T31 and 12g of modified powder evenly, then add 150g of epoxy resin E51 and stir at 1000r / min for 50min. After degassing under vacuum for 60min, extrude and granulate to obtain the sheath material.

[0093] S12: Twist 10 copper wires with a diameter of 5mm together to form a conductor;

[0094] S13: A layer of phlogopite tape is wound around the surface of the conductor, and then an insulating material is extruded onto the surface using an extruder and cured to form a 2.5mm thick insulating layer, thus obtaining an insulated wire core; wherein, the curing treatment is as follows: first, it is cured at 160℃ and 1MPa for 2 hours, then cured at 210℃ and 10MPa for 3 hours, and finally cured at 235℃ and 10MPa for 3 hours.

[0095] S14: Six insulated wire cores are twisted together to form a cable core, and polypropylene rope is filled between the cable cores. Then, the cores are wrapped and fixed with binding tape. A layer of sheath material is then extruded onto the outer surface and cured at 135℃ and 10MPa for 40 minutes to form a 3mm thick sheath layer, thus obtaining a fire-resistant cable.

[0096] Comparative Example 1:

[0097] Compared with Example 1, this comparative example only did not add "modified basalt" in the preparation process of S6. All other steps and parameters were the same, and will not be repeated here. The final result was a fire-resistant cable.

[0098] Comparative Example 2:

[0099] Compared with Example 1, this comparative example only did not add the "synergist" in the preparation process of S6. All other steps and parameters were the same, and will not be repeated here. The final result was a fire-resistant cable.

[0100] Comparative Example 3:

[0101] Compared with Example 1, this comparative example only replaces the "modified powder" added in the preparation process of S11 with the "grafted powder" prepared in S9. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a fire-resistant cable is obtained.

[0102] Comparative Example 4:

[0103] Compared with Example 1, this comparative example only did not add "modified powder" in the preparation process of S11. All other steps and parameters are the same, and will not be repeated here. The final result is a fire-resistant cable.

[0104] Comparative Example 5:

[0105] Compared with Example 1, this comparative example only replaces the "modified basalt" added in the preparation process of S11 with the "grafted basalt" prepared in S2. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a fire-resistant cable is obtained.

[0106] Comparative Example 6:

[0107] Compared with Example 1, this comparative example only did not add "modified basalt" in the preparation process of S11. All other steps and parameters were the same, and will not be repeated here. The final result was a fire-resistant cable.

[0108] Performance testing:

[0109] Abrasion resistance testing:

[0110] Referring to GB / T 3960-2016 "Test Method for Sliding Friction and Wear of Plastics", the wear amount (g) of the sheath layer of the fire-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was determined when the load was 30N, the sliding speed was 2m / s, and the sliding distance was 5000m. The test results are shown in Table 1.

[0111] Determination of limiting oxygen index:

[0112] Referring to GB / T 2406.1-2008 "Determination of Burning Performance of Plastics by Oxygen Index Method", the limiting oxygen index (%) of the fire-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was determined, and the test results are shown in Table 1.

[0113] Fire resistance testing:

[0114] Referring to GB 12666.6-2008 "Fire-resistant Cables" standard, the fire-resistant time (min) of the fire-resistant cables prepared in Examples 1-3 and Comparative Examples 1-6 of this invention at 950-1000℃ was determined, and the test results are shown in Table 1.

[0115] Determination of tensile strength:

[0116] Referring to GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General", the tensile strength (MPa) of the fire-resistant cable sheath materials prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was determined, and the test results are shown in Table 1.

[0117] Determination of performance stability:

[0118] Referring to GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General", the tensile strength retention rate (%) of the fire-resistant cable sheathing materials prepared in Examples 1-3 and Comparative Examples 1-6 of this invention at 230°C was determined to reflect their performance stability at high temperatures. The test results are shown in Table 1.

[0119] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-6

[0120]

[0121] Data Analysis:

[0122] As can be seen from Table 1, the fire-resistant cable prepared according to the embodiments of the present invention has excellent wear resistance, limiting oxygen index, fire resistance, tensile strength and high temperature tensile strength stability.

[0123] In Comparative Example 6, no modified basalt was added to the sheath material. In Comparative Example 5, the modified basalt was replaced in equal amounts with grafted basalt that had not been modified with sodium phytate and nickel acetate. The wear resistance, limiting oxygen index, fire resistance, tensile strength, and high-temperature tensile strength stability of Comparative Example 6 were all lower than those of Examples 1-3, and the decrease was greater in Comparative Example 6. This indicates that the addition of modified basalt in this invention can more effectively improve the various performance characteristics of the cable. At the same time, Comparative Example 1, which did not add modified basalt to the insulation material, also showed a decrease in limiting oxygen index and fire resistance, which also indicates that the modified basalt in this invention can improve fire resistance and flame retardancy.

[0124] Comparative Example 2 did not add any synergist to the insulating material, and its limiting oxygen index and fire resistance time were significantly reduced. This is because the synergist decomposes at high temperatures to form a stable and dense phosphorus-nitrogen composite carbonized layer, which can effectively improve flame retardancy and fire resistance.

[0125] Comparative Example 4 did not add modified powder to the sheath material. In Comparative Example 3, the modified powder was replaced in equal amounts with grafted powder of ungrafted hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone polymer. The results showed that all properties were reduced, and the reduction was greater in Comparative Example 4. This is because the lamellar structure of the layered double hydroxide in the modified powder can absorb heat and release inert gases such as carbon dioxide when decomposed at high temperature, and form a physical barrier layer to slow down heat transfer and inhibit the thermal degradation and softening of the substrate. The polyphosphazene crosslinking network introduced after modification can improve the hardness of the material, reduce filler shedding during wear, and form a phosphorus-based flame-retardant coating during combustion. The glassy phosphorus oxide coating generated by decomposition can also isolate oxygen and inhibit the thermal degradation and softening of the substrate. The inorganic rigid skeleton and organic crosslinking structure after modification can synergistically improve wear resistance, flame retardancy, fire resistance, tensile strength and high-temperature performance stability.

[0126] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing a fire-resistant cable, characterized in that, Includes the following steps: S1: Copper wires are twisted together to form a conductor, then a layer of phlogopite tape is wound around the surface of the conductor, and then an insulating material is extruded onto the surface and cured to form an insulating layer, thus obtaining an insulated wire core; S2: Twist 4-6 insulated wire cores together to form a cable core, fill the gaps between the cable cores with polypropylene rope, then wrap and fix it with binding tape, then extrude a layer of sheath material on the outer surface and cure it a second time to form a sheath layer, thus obtaining a fire-resistant cable. The insulating material comprises the following raw materials in parts by weight: 200-250 parts of epoxy resin E51, 10-12 parts of synergist, 20-25 parts of modified basalt, and 92-112 parts of sulfamic acid. The sheath material comprises the following raw materials in parts by weight: 5-7 parts of chopped carbon fiber filaments, 35-45 parts of modified basalt, 18-20 parts of curing agent T31, 10-12 parts of modified powder, and 100-150 parts of epoxy resin E51. The synergist was prepared by reacting phenylphosphonic dichloride with anhydrous piperazine in the presence of triethylamine; The modified basalt is basalt that has been pretreated with sodium hydroxide aqueous solution, grafted with silane coupling agent KH550, and then modified with sodium phytate and nickel acetate. The modified powder is a mixed powder obtained by reacting magnesium nitrate and aluminum nitrate, which is first grafted with silane coupling agent KH-550, and then grafted with a polymer of hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone.

2. The method for preparing the fire-resistant cable according to claim 1, characterized in that, The method for preparing the insulating material is as follows: Add synergists to epoxy resin E51 and stir well. Then add modified basalt and stir well. Then add sulfamic acid at 115-125℃ and mix for 5-7 minutes. After degassing, extrude and granulate to obtain the insulating material.

3. The method for preparing the fire-resistant cable according to claim 1, characterized in that, The preparation method of the sheath material is as follows: Short carbon fiber filaments, modified basalt, curing agent T31, and modified powder are mixed evenly, then epoxy resin E51 is added and stirred evenly. After degassing, the mixture is extruded and granulated to obtain the sheath material.

4. The method for preparing the fire-resistant cable according to claim 1, characterized in that, The curing process is as follows: first, cure at 150-160℃ and 1MPa for 1.5-2 hours, then cure at 190-210℃ and 10MPa for 2-3 hours, and finally cure at 225-235℃ and 10MPa for 2-3 hours. The secondary curing process involves curing at 125-135℃ and 8-10MPa for 30-40 minutes.

5. The method for preparing the fire-resistant cable according to claim 1, characterized in that, The preparation method of the synergist is as follows: A1: Dissolve phenylphosphonic dichloride in N,N-dimethylformamide to obtain a phenylphosphonic dichloride solution; A2: Add anhydrous piperazine and triethylamine to N,N-dimethylformamide and stir at 1-10℃ for 30-40 min. Then add phenylphosphonic dichloride solution dropwise and stir at 1-10℃ for 2-3 h, then stir at 25-35℃ for 10-15 h. Finally, reflux at 75-100℃ for 10-12 h. After cooling, filter and wash the filter cake. After vacuum drying, the synergist is obtained.

6. The method for preparing the fire-resistant cable according to claim 5, characterized in that, The mass ratio of phenylphosphonic dichloride to N,N-dimethylformamide in A1 is 10-12:20-24; The mass ratio of N,N-dimethylformamide, anhydrous piperazine, triethylamine, and phenylphosphonic dichloride solution in A2 is 60-72. 8.6-10.3：10.2-12.2：30-36。 7. The method for preparing the fire-resistant cable according to claim 1, characterized in that, The modified basalt is prepared as follows: B1: Basalt was added to an aqueous sodium hydroxide solution and stirred at 98-100℃ for 2-3 hours. After centrifugation and washing of the precipitate, the pretreated basalt was obtained after drying. B2: Add pretreated basalt, silane coupling agent KH550, and glacial acetic acid to deionized water and stir at 75-80℃ for 3-4 hours. Then centrifuge, wash the precipitate, and dry it to obtain grafted basalt. B3: Add grafted basalt and sodium phytate to deionized water and stir at 75-80℃ for 1-1.5h. Then add nickel acetate and stir at 75-80℃ for 2-3h. Then centrifuge and wash the precipitate, and dry to obtain modified basalt.

8. The method for preparing the fire-resistant cable according to claim 7, characterized in that, The mass ratio of sodium hydroxide aqueous solution to basalt in B1 is 900-1000:60-70; The concentration of the sodium hydroxide aqueous solution described in B1 is 4 mol / L; The mass ratio of deionized water, pretreated basalt, silane coupling agent KH550, and glacial acetic acid in B2 is 800-1000:60-70:2-3.5:0.5-1; The mass ratio of deionized water, grafted basalt, sodium phytate, and nickel acetate described in B3 is 1500-2500:60-70:108-156:63-87.

9. The method for preparing the fire-resistant cable according to claim 1, characterized in that, The modified powder is prepared as follows: C1: Add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to deionized water and stir well to obtain a mixed solution; C2: Add sodium hydroxide and sodium carbonate to deionized water and stir well. After passing nitrogen gas, add the mixture dropwise and stir at 68-70℃ under nitrogen atmosphere for 18-20h. After cooling, centrifuge to separate and wash the precipitate. Vacuum dry, grind and sieve to obtain mixed powder. C3: Add the mixed powder to anhydrous ethanol and sonicate, then add dropwise an ethanol solution of silane coupling agent KH-550 and stir at 45-50℃ for 3-4 hours. Then centrifuge and wash the precipitate, vacuum dry, grind and sieve to obtain the grafted powder. C4: Grafted powder is added to anhydrous acetonitrile and sonicated. After purging with nitrogen, hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone are added at 0-5℃ and stirred for 10-20 min. Then, triethylamine is added dropwise and stirred at 0-5℃ for 1-2.5 h. After stirring at 65-70℃ for 18-20 h, the mixture is cooled, centrifuged, and the precipitate is washed. The precipitate is then vacuum dried, ground, and sieved to obtain the modified powder.

10. The method for preparing the fire-resistant cable according to claim 9, characterized in that, The mass ratio of deionized water, magnesium nitrate hexahydrate, and aluminum nitrate nonahydrate in C1 is 200-250: 20.6-24.7: 9.4-11.3; The mass ratio of deionized water, sodium hydroxide, sodium carbonate, and the mixed solution described in C2 is 200-250: 8.8-10.6: 1.3-1.6: 230-286; The mass ratio of anhydrous ethanol, mixed powder, and silane coupling agent KH-550 in the ethanol solution described in C3 is 200-240:10-12:10-12; The ethanol solution of the silane coupling agent KH-550 described in C3 has a mass fraction of 3%; The mass ratio of anhydrous acetonitrile, grafted powder, hexachlorocyclotriphosphazene, 4,4'-dihydroxydiphenyl sulfone, and triethylamine in C4 is 200-240:10-12:12.5-15:31-37.2:11-13.

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