A preparation method of B1 flame retardant and fire resistant control cable

Abstract

The present invention discloses a method for preparing a Class B1 flame-retardant and fire-resistant control cable, belonging to the technical field of flame-retardant and fire-resistant cables. The method is used to solve the technical problem in the prior art that the mechanical strength and fire-resistant and flame-retardant properties of inorganic flame-retardant modified fire-resistant and flame-retardant control cables need to be further improved. The method comprises the following steps: arranging a plurality of cable cores in parallel, filling the gaps between the cable cores with filling ropes to form a filling layer, and wrapping the plurality of cable cores filled with the filling layer together using wrapping tape to form a wrapping layer on the exterior of the plurality of cable cores. The method uses maleic anhydride-modified polyethylene as a compatibilizing agent and cross-links and strengthens the polyethylene with modified graphite and modified polysiloxane, thereby effectively improving not only the mechanical strength of the cable material but also its fire-resistant and flame-retardant properties.

Description

Technical Field

[0001] The present invention relates to the technical field of flame-retardant and fire-resistant cables, and in particular to a method for preparing a B1-class flame-retardant and fire-resistant control cable. Background Art

[0002] Electrical fires rank first among all types of fires. 52% of fires with identified causes are caused by electricity. Electrical fires are highly harmful to society. Regulations and standards in countries around the world have provisions on the combustion performance of cables. my country's GB31247-2014 "Classification of Combustion Performance of Electrical Cables and Optical Fiber Cables" promulgated and implemented on September 1, 2015, modified and adopted the EN50575 and EN13501-6 standards, stipulating four classification standards: A, B1, B2, and B3. At present, in the design and construction of key places with dense crowds of people, such as airports and subways, and places requiring special protection, it is gradually required to use flame-retardant and fire-resistant cable products with a combustion grade of B1.

[0003] However, the flame retardancy of cables in the prior art mainly relies on the sheath layer structure with external protection. Flame retardants are usually used to modify the cable materials for flame retardancy during processing. However, organic flame retardant materials or halogens will produce a large amount of toxic smoke when burned, which is difficult to meet the B1 level requirements. Although inorganic flame retardants can avoid the production of toxic smoke during combustion, the flame retardant effect of inorganic flame retardant materials is poor, the amount added is large, and the compatibility of inorganic fillers with cable materials is poor, making it difficult to disperse evenly in the cable materials, resulting in the mechanical strength of the cable needing to be further improved, resulting in the mechanical strength and fire retardant properties of the inorganic flame retardant modified fire-resistant flame retardant control cable in the prior art needing to be further improved.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a B1-class flame-retardant and fire-resistant control cable, which is used to solve the technical problem in the prior art that the mechanical strength and fire-resistant and flame-retardant properties of inorganic flame-retardant modified fire-resistant and flame-retardant control cables need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solution: A method for preparing a B1-class flame-retardant and fire-resistant control cable, comprising the following steps:

[0007] S1. Arrange several cable cores in parallel, and fill the gaps between the cable cores with filling ropes to form a filling layer. Use a wrapping tape to wrap the several cable cores filled with the filling layer together to form a wrapping layer outside the several cable cores.

[0008] S2, adding low-density polyethylene, maleic anhydride-modified polyethylene, modified polysiloxane, modified graphite, initiator and auxiliary additives into a twin-screw extruder, melt-mixing for 8 minutes, and extruding and coating the obtained mixture on the outside of the wrapping layer to obtain a crude control cable;

[0009] S3. Place the crude control cable product in a water vapor box at a temperature of 100-120° C. and perform heat preservation treatment for 6-8 hours to form a sheath layer outside the wrapping layer to obtain the control cable.

[0010] Furthermore, in step S1, the cable core includes a conductor, an insulation layer and a fire-resistant layer arranged in sequence from the inside to the outside, the conductor is oxygen-free copper, the insulation layer is obtained by coating cross-linked polyethylene on the outside of the conductor, the fire-resistant layer is obtained by wrapping synthetic phlogopite tape on the outside of the insulation layer, and the filling rope is a low-smoke halogen-free PP flame-retardant filling rope.

[0011] Furthermore, in step S2, the weight ratio of the low-density polyethylene, maleic anhydride-modified polyethylene, modified polysiloxane, modified graphite, initiator and auxiliary additives is 80-90:40-50:25-35:17-19:2-3:3-5, the initiator is dicumyl peroxide, and the auxiliary additives are composed of a dispersant, a plasticizer, an antioxidant, and a lubricant in a weight ratio of 3:5:2:3. The dispersant is a stearate, the plasticizer is a phthalate, the antioxidant is any one of antioxidant AW, antioxidant DNP, and antioxidant CPPD, and the lubricant is one or more of butyl stearate, oleamide, and ethylene bisstearamide. The temperatures of the six temperature sections of the twin-screw extruder from the feed end to the discharge end are 175°C, 180°C, 180°C, 180°C, 180°C, and 185°C, respectively.

[0012] Furthermore, the preparation method of maleic anhydride modified polyethylene is: low-density polyethylene, maleic anhydride and an initiator are mixed, and then added into a twin-screw extruder, melt-mixed for 4-6 minutes and then extruded, cooled and crushed to obtain maleic anhydride modified polyethylene.

[0013] The synthetic reaction mechanism of maleic anhydride modified polyethylene is:

[0014] In a high-temperature environment, dicumyl peroxide decomposes to produce free radicals that attack the hydrogen atoms on the low-density polyethylene chain and the double bonds on the maleic anhydride molecules, causing the CH bonds and double bonds to break and open, forming free radicals. Then, free radicals combine with each other to form maleic anhydride modifications on the low-density polyethylene molecular chain, thereby preparing maleic anhydride-modified polyethylene.

[0015] Furthermore, the weight ratio of the low-density polyethylene, maleic anhydride and initiator is 60:1:0.2, the initiator is dicumyl peroxide, and the temperatures of the six temperature zones of the twin-screw extruder from the feed end to the discharge end are 175°C, 180°C, 180°C, 180°C, 180°C and 185°C, respectively.

[0016] Furthermore, the modified polysiloxane is processed by the following steps:

[0017] A1. Mixing a modified flame retardant, octamethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and xylene, raising the temperature of the reaction system to 110-120° C., adding a catalyst to the reaction system, and keeping the temperature for 4-6 hours. Adding a capping agent to the reaction system, keeping the temperature for 3-5 hours, and post-treating to obtain polysiloxane;

[0018] A2. Under an inert atmosphere, polysiloxane and xylene were mixed and stirred, the temperature of the reaction system was raised to 70-80°C, isocyanate methyltrimethoxysilane was added to the reaction system, and the reaction was kept warm for 60-80 minutes, and post-treated to obtain modified polysiloxane.

[0019] The synthetic reaction formula of modified polysiloxane is:

[0020]

[0021] Where: .

[0022] The synthetic reaction mechanism of modified polysiloxane is:

[0023] Under the catalysis of formic acid, the methoxysilane groups in the modified flame retardant modified with dimethoxysilane, octamethylcyclotetrasiloxane and 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane molecules undergo hydrolysis reaction to generate silanols, which then condense with each other to prepare a long polysiloxane chain with unsaturated double bonds and phosphorus modification. During the reaction, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane is used as a chain-terminating end group to form a hydroxyl modification on the polysiloxane chain segment; the end-capped hydroxyl group on the polysiloxane molecular chain then acts as an active reaction site to undergo a condensation reaction with isocyanate methyltrimethoxysilane molecules to modify the polysiloxane chain with trimethoxysilane to prepare a modified polysiloxane.

[0024] Further, in step A1, the modified flame retardant, octamethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, xylene, catalyst and end-capping agent are used in a ratio of 0.8-1.2g:7-9g:2-3g:50mL:5mL:0.6g, the catalyst is a 20wt% formic acid aqueous solution, the end-capping agent is 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and the post-treatment includes: after the reaction is completed, the reaction system temperature is reduced to At room temperature, 1 wt% sodium hydroxide solution is added to the reaction system to adjust the system pH to 7, the system is allowed to stand for separation, the organic phase is washed with purified water until neutral and then dried, the organic phase is transferred to a rotary evaporator with a water bath temperature of 90-100° C., and low-boiling substances are removed by evaporation under reduced pressure to obtain a polysiloxane; in step A2, the polysiloxane, xylene, and isocyanate methyltrimethoxysilane are used in a ratio of 5 g:50 mL:1 g, and the post-treatment includes: raising the temperature of the reaction system to 90-100° C., and removing low-boiling substances by evaporation under reduced pressure to obtain a modified polysiloxane.

[0025] Furthermore, the preparation method of the modified flame retardant is as follows: under an inert atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, tetrahydrofuran and triethylamine are mixed, the temperature of the reaction system is increased to 40-50°C, stirred until the system is dissolved, methyl-(3-isocyanatepropyl)dimethylsilane is added to the reaction system, the reaction is kept warm for 8-10 hours, and post-processed to obtain the modified flame retardant.

[0026] The synthetic reaction formula of the modified flame retardant is:

[0027]

[0028] The synthetic reaction mechanism of the modified flame retardant is:

[0029] The modified flame retardant is prepared by modifying the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide molecule with dimethoxysilane, using the hydroxyl group on the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide molecule as an active reaction site to undergo a condensation reaction with the isocyanate group on the methyl-(3-isocyanatopropyl)dimethylsilane molecule.

[0030] The mass analysis data of the modified flame retardant material are: m / z: 435.1267 (100.0%), 436.1301 (21.6%), 436.1263 (5.1%), 437.1235 (3.3%), 437.1334 (2.2%), 437.1309 (1.2%), 437.1296 (1.1%).

[0031] Furthermore, the molar ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide and methyl-(3-isocyanatepropyl)dimethylsilane is 1:1, and the amount ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, tetrahydrofuran and triethylamine is 1g:10mL:0.1g. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 50-60°C, and low-boiling substances are distilled off under reduced pressure to obtain a modified flame retardant.

[0032] Furthermore, the modified graphite is obtained by processing the following steps:

[0033] B1. Mix and stir the loaded graphite and buffer solution, raise the temperature of the reaction system to 70-80°C, add dopamine hydrochloride to the reaction system, keep the temperature for 8-10 hours, and post-treat to obtain activated graphite;

[0034] B2. Mix activated graphite, ethanol and KH-560, raise the temperature of the reaction system to 50-60°C, add alkali solution to the reaction system, keep the temperature and react for 55-65 minutes, and post-treat to obtain modified graphite.

[0035] The synthetic reaction mechanism of modified graphite is:

[0036] Activated graphite is prepared by dispersing loaded graphite in a buffer solution, and then allowing self-polymerization reaction between dopamine hydrochloride molecules to form a polydopamine layer coating on the graphite surface. KH-560 is hydrolyzed under the catalysis of sodium hydroxide to generate silanols, which undergo condensation reaction with active functional groups on the surface of the activated graphite. KH-560 is grafted onto the surface of the activated graphite to prepare modified graphite.

[0037] Furthermore, in step B1, the ratio of the loaded graphite, buffer and dopamine hydrochloride is 3g:30mL:1g, the buffer is a 1mol / L Tris-hydrochloride solution with a pH of 8.5, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtered, the filter cake is washed with purified water three times and then dried, and the filter cake is transferred to a drying oven at a temperature of 70-80°C and vacuum dried to a constant weight to obtain activated graphite.

[0038] Furthermore, in step B2, the ratio of the activated graphite, ethanol, KH-560 and alkali solution is 3g:20mL:1g:5mL, the alkali solution is 0.3-0.5mol / L sodium hydroxide solution, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtered, the filter cake is washed with purified water until neutral and then dried, and the filter cake is transferred to a drying oven at a temperature of 70-80°C and vacuum dried to constant weight to obtain modified graphite.

[0039] Furthermore, the supported graphite is processed by the following steps:

[0040] C1. Mix aluminum chloride, magnesium chloride and dilute hydrochloric acid, stir until the system is dissolved, add expandable graphite to the reaction system, ultrasonically disperse for 40-60 minutes, and post-treat to obtain a loaded graphite precursor;

[0041] C2. Add the supported graphite precursor to the alkaline solution, stir at room temperature for 30-50 minutes, and post-treat to obtain supported graphite.

[0042] The synthetic reaction mechanism of supported graphite is:

[0043] Dilute hydrochloric acid is used as a solvent to promote the dissolution and dispersion of aluminum chloride and magnesium chloride, ultrasonic dispersion is used to promote the penetration of metal ions into the interlayer structure of graphite, low-boiling substances are distilled off under reduced pressure to remove part of the water and volatile impurities in the solution, and the interaction between the metal ions and the graphite layers is promoted to form a supported graphite precursor; after the supported graphite precursor is mixed with a sodium hydroxide solution, the metal ions react with hydroxide ions to generate corresponding magnesium and aluminum metal hydroxide precipitates or complexes that remain in the interlayer structure of the graphite or are partially deposited on the surface of the graphite to obtain supported graphite.

[0044] Furthermore, in step C1, the amount ratio of the aluminum chloride, magnesium chloride, dilute hydrochloric acid and expandable graphite is 3g:2g:50mL:15g, the concentration of the dilute hydrochloric acid is 0.8-1.5mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 70-80°C, and low-boiling substances are removed under reduced pressure to obtain a loaded graphite precursor; in step C2, the amount ratio of the loaded graphite precursor and the alkaline solution is 1g:5mL, and the alkaline solution is 3-5mol / L sodium hydroxide solution. The post-treatment includes: after the reaction is completed, filtering, rinsing the filter cake with purified water until neutral and then drying, transferring the filter cake to a drying oven at a temperature of 70-80°C, and vacuum drying to constant weight to obtain loaded graphite.

[0045] The present invention has the following beneficial effects:

[0046] 1. The B1-class flame-retardant and fire-resistant control cable of the present invention coats the conductor layer by layer with an insulating layer and a fire-resistant layer, so that the cable conductor has good high-temperature resistance. After filling it with a filling rope, a semiconductor shielding tape is selected to wrap it to reduce the interference of the electromagnetic field on the conductor. Then, a sheath layer is melt-extruded and coated on the outside of the wrapping layer. By optimizing the molecular composition of the sheath layer material, a synergistic flame retardant system is constructed on the cable sheath layer with expanded graphite loaded with metal particles and modified polysiloxane modified with phosphorus, thereby improving the flame retardant performance of the cable material. In addition, by introducing active reaction sites on the constituent materials, cross-linking between material molecules is promoted, the cross-linking degree of the material is increased, and the high-temperature resistance and mechanical strength of the material are further improved.

[0047] 2. The B1-class flame-retardant and fire-resistant control cable of the present invention enhances the reactivity and nitrogen content of the activated graphite by loading aluminum and magnesium metal particles on expanded graphite and then coating it with polydopamine. The expanded graphite can expand rapidly at high temperatures to form a carbon layer on the surface of the polymer, separating the combustibles from the heat source and absorbing a large amount of heat. Aluminum and magnesium will oxidize at high temperatures to form metal oxides with a higher melting point, forming a physical barrier to slow combustion, which cooperates with the expanded graphite to jointly improve its fire resistance and flame retardant properties. Polydopamine is rich in nitrogen and increases the nitrogen content in the activated graphite. Nitrogen can participate in the formation of stable nitrides or nitrogen oxides during the combustion process, which helps to inhibit the combustion reaction. The long polysiloxane chain segment body on the modified polysiloxane molecular chain and the phosphorus-containing compound modified on the chain segment are further combined with the modified graphite to further improve the fire resistance stability and flame retardant properties of the control cable.

[0048] 3. The B1-class flame-retardant and fire-resistant control cable of the present invention can effectively improve the dispersibility of the modified graphite in the sheath layer material by forming a polydopamine coating and epoxy group modification on the modified graphite. In addition, under a high temperature environment, the epoxy group modified on the modified graphite particles can undergo ring-opening condensation with active groups such as amino and hydroxyl groups to promote intermolecular crosslinking, and enhance its polarity by modifying the polyethylene with maleic anhydride. Through the mechanism of similar chain segments, the maleic anhydride-modified polyethylene can be uniformly dispersed in the low-density polyethylene, making it easier for the polyethylene to form hydrogen bonds with the phosphorus-containing and olefin-modified polysiloxane segments, thereby enhancing the interaction between the two polymers. Under the action of the initiator, the unsaturated double bonds on the modified polysiloxane molecular chain are initiated to undergo free radical polymerization with the polyethylene to form chemical bonds. At the same time, after high-temperature steam treatment, the hydrolysis and condensation of the siloxane bonds on the molecules can be promoted, further improving the degree of crosslinking between the molecules, so that the cable sheath layer exhibits good mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the present invention.

[0051] In the figure: 100, cable core; 101, conductor; 102, insulation layer; 103, fire-resistant layer; 200, wrapping layer; 300, filling layer. DETAILED DESCRIPTION

[0052] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] In the present invention, the cross-linked polyethylene is selected from Tianjin No. 1 Branch Cable Co., Ltd., model number RS485;

[0054] In the present invention, the synthetic phlogopite tape is selected from Shanghai Haoliang Optoelectronic Equipment Co., Ltd., with a mica content of 80%, a thickness of 0.6-0.8 mm, a width of 900-1000 mm, a breakdown strength of >15 KV / mm, and a tensile strength of 2100 N / 15 mm;

[0055] In the present invention, the low-smoke halogen-free PP flame-retardant filling rope is selected from Ningjin County Haoxin New Material Technology Co., Ltd., and the oxygen index is 28%;

[0056] In the present invention, the wrapping tape is a semiconductor shielding cloth tape, selected from Qufu Jintong Mining Equipment Co., Ltd., and its backing material is a semiconductor;

[0057] In the present invention, the density of low-density polyethylene is 0.918 g / cm 3 , the melt mass flow rate is 70g / 10min (190℃, 2.16kg).

[0058] Example 1

[0059] This embodiment provides a method for preparing a cable material for a Class B1 flame-retardant and fire-resistant control cable, comprising the following steps:

[0060] S1. Preparation of maleic anhydride modified polyethylene

[0061] Weigh out 60 parts of low-density polyethylene, 1 part of maleic anhydride and 0.2 parts of dicumyl peroxide as an initiator, and then add them to a twin-screw extruder. The temperatures of the six temperature sections of the twin-screw extruder from the feed end to the discharge end are 175° C., 180° C., 180° C., 180° C., 180° C. and 185° C., respectively. Adjust the main shaft speed of the twin-screw extruder, maintain melt mixing for 4 minutes, then extrude, cool and crush to obtain maleic anhydride-modified polyethylene.

[0062] S2. Preparation of modified polysiloxane

[0063] Weigh: 24.6 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, 216 mL of tetrahydrofuran, and 2.2 g of triethylamine are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is raised to 40°C and stirred until the system is dissolved. 18.9 g of methyl-(3-isocyanatepropyl)dimethylsilane is added to the three-necked flask and the reaction is kept warm for 8 hours. The temperature of the three-necked flask is raised to 50°C and low-boiling substances are evaporated under reduced pressure to obtain a modified flame retardant.

[0064] Weigh: 80 g of modified flame retardant, 700 g of octamethylcyclotetrasiloxane, 200 g of 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and 5000 mL of xylene are added to a reactor and stirred. The temperature of the reactor is raised to 110 ° C. 500 mL of 20 wt% formic acid aqueous solution is added to the reactor and the reaction is kept warm for 4 h. 60 g of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, a capping agent, is added to the reactor and the reaction is kept warm for 3 h. The temperature of the reactor is lowered to room temperature. 1 wt% sodium hydroxide solution is added to the reaction system to adjust the pH of the system to 7. The solution is allowed to stand and separate. The organic phase is washed with purified water until neutral and then dried with anhydrous sodium sulfate for 4 h. Filtered, the organic phase is transferred to a rotary evaporator with a water bath temperature of 90 ° C. Low boiling substances are evaporated under reduced pressure to obtain polysiloxane;

[0065] Under an inert atmosphere, 500 g of polysiloxane and 5000 mL of xylene were weighed and added to a nitrogen-protected reactor with stirring. The temperature of the reactor was raised to 70°C. 100 g of isocyanate methyltrimethoxysilane was added to the reactor and the reaction was kept warm for 60 minutes. The temperature of the reactor was raised to 90°C, and low-boiling substances were evaporated under reduced pressure to obtain modified polysiloxane.

[0066] S3. Preparation of loaded graphite

[0067] Weigh 30 g of aluminum chloride, 20 g of magnesium chloride, and 500 mL of 0.8 mol / L hydrochloric acid into a three-necked flask and stir until the system is dissolved. Add 150 g of expandable graphite to the three-necked flask and ultrasonically disperse for 40 min. Raise the temperature of the three-necked flask to 70°C and remove low-boiling substances under reduced pressure to obtain a supported graphite precursor.

[0068] The loaded graphite precursor and 3 mol / L sodium hydroxide solution were mixed at a ratio of 1 g:5 mL, stirred at room temperature for 30 min, filtered, and the filter cake was rinsed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 70°C and vacuum dried to constant weight to obtain loaded graphite.

[0069] S4. Preparation of modified graphite

[0070] Weigh: 120 g of loaded graphite and 1200 mL of 1 mol / L Tris-hydrochloride solution are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 70°C. 40 g of dopamine hydrochloride is added to the three-necked flask and the reaction is kept warm for 8 hours. The temperature of the three-necked flask is lowered to room temperature, and the filter cake is filtered. The filter cake is washed three times with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 70°C and vacuum dried to a constant weight to obtain activated graphite;

[0071] Weigh: 120 g of activated graphite, 800 mL of ethanol and 40 g of KH-560 were added to a three-necked flask and stirred. The temperature of the three-necked flask was raised to 50°C, and 200 mL of 0.3 mol / L sodium hydroxide solution was added to the reaction system. The reaction was kept warm for 55 minutes. The temperature of the three-necked flask was lowered to room temperature, filtered, and the filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at a temperature of 7°C and vacuum dried to constant weight to obtain modified graphite.

[0072] S5. Preparation of cable materials

[0073] Calcium stearate, dioctyl phthalate, antioxidant AW, and butyl stearate are uniformly mixed in a weight ratio of 3:5:2:3 to obtain an auxiliary additive;

[0074] The following components were weighed in parts by weight: 80 parts of low-density polyethylene, 40 parts of maleic anhydride-modified polyethylene, 25 parts of modified polysiloxane, 17 parts of modified graphite, 2 parts of initiator dicumyl peroxide, and 3 parts of auxiliary additives, and mixed to obtain a cable material.

[0075] Example 2

[0076] This embodiment provides a method for preparing a cable material for a Class B1 flame-retardant and fire-resistant control cable, comprising the following steps:

[0077] S1. Preparation of maleic anhydride modified polyethylene

[0078] Weigh out 60 parts of low-density polyethylene, 1 part of maleic anhydride and 0.2 parts of dicumyl peroxide as an initiator, and then add them to a twin-screw extruder. The temperatures of the six temperature zones of the twin-screw extruder from the feed end to the discharge end are 175° C., 180° C., 180° C., 180° C., 180° C. and 185° C., respectively. Adjust the main shaft speed of the twin-screw extruder, maintain melt mixing for 5 minutes, then extrude, cool and crush to obtain maleic anhydride-modified polyethylene.

[0079] S2. Preparation of modified polysiloxane

[0080] Weigh: 24.6 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, 216 mL of tetrahydrofuran, and 2.2 g of triethylamine are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is raised to 45° C. and stirred until the system is dissolved. 18.9 g of methyl-(3-isocyanatepropyl)dimethylsilane is added to the three-necked flask and the reaction is kept warm for 9 hours. The temperature of the three-necked flask is raised to 50-60° C. and low-boiling substances are evaporated under reduced pressure to obtain a modified flame retardant;

[0081] Weigh: 100 g of modified flame retardant, 800 g of octamethylcyclotetrasiloxane, 250 g of 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and 5000 mL of xylene are added to a reactor and stirred. The temperature of the reactor is raised to 115 ° C. 500 mL of 20 wt% formic acid aqueous solution is added to the reactor and kept warm for 5 h. 60 g of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, a capping agent, is added to the reactor and kept warm for 4 h. The temperature of the reactor is lowered to room temperature. 1 wt% sodium hydroxide solution is added to the reaction system to adjust the pH of the system to 7. The solution is allowed to stand and separate. The organic phase is washed with purified water until neutral and then dried with anhydrous sodium sulfate for 5 h. Filtered, the organic phase is transferred to a rotary evaporator with a water bath temperature of 95 ° C. Low boiling substances are evaporated under reduced pressure to obtain polysiloxane;

[0082] Under an inert atmosphere, 500 g of polysiloxane and 5000 mL of xylene were weighed and added to a nitrogen-protected reactor with stirring. The temperature of the reactor was raised to 75° C., 100 g of isocyanate methyltrimethoxysilane was added to the reactor, and the reaction was kept warm for 70 minutes. The temperature of the reactor was raised to 95° C., and low-boiling substances were evaporated under reduced pressure to obtain modified polysiloxane.

[0083] S3. Preparation of loaded graphite

[0084] Weigh 30 g of aluminum chloride, 20 g of magnesium chloride, and 500 mL of 1.2 mol / L hydrochloric acid into a three-necked flask and stir until the system is dissolved. Add 150 g of expandable graphite to the three-necked flask and ultrasonically disperse for 50 min. Raise the temperature of the three-necked flask to 75°C and remove low-boiling substances under reduced pressure to obtain a supported graphite precursor.

[0085] The loaded graphite precursor and 4 mol / L sodium hydroxide solution were mixed at a ratio of 1 g:5 mL, stirred at room temperature for 40 min, filtered, and the filter cake was rinsed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 75°C and vacuum dried to constant weight to obtain loaded graphite.

[0086] S4. Preparation of modified graphite

[0087] Weigh: 120 g of loaded graphite and 1200 mL of 1 mol / L Tris-hydrochloride solution are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 75°C. 40 g of dopamine hydrochloride is added to the three-necked flask and the reaction is kept warm for 9 hours. The temperature of the three-necked flask is lowered to room temperature, and the mixture is filtered. The filter cake is washed three times with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and dried under vacuum to a constant weight to obtain activated graphite;

[0088] Weigh: 120 g of activated graphite, 800 mL of ethanol and 40 g of KH-560 are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 55°C, 200 mL of 0.4 mol / L sodium hydroxide solution is added to the reaction system, and the reaction is kept warm for 60 minutes. The temperature of the three-necked flask is lowered to room temperature, filtered, and the filter cake is washed with purified water until neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and vacuum dried to constant weight to obtain modified graphite.

[0089] S5. Preparation of cable materials

[0090] Zinc stearate, dibutyl phthalate, antioxidant DNP, and oleamide are uniformly mixed in a weight ratio of 3:5:2:3 to obtain an auxiliary additive;

[0091] The following materials were weighed in parts by weight: 85 parts of low-density polyethylene, 45 parts of maleic anhydride-modified polyethylene, 30 parts of modified polysiloxane, 18 parts of modified graphite, 2.5 parts of initiator dicumyl peroxide and 4 parts of auxiliary additives, and mixed to obtain a cable material.

[0092] Example 3

[0093] This embodiment provides a method for preparing a cable material for a Class B1 flame-retardant and fire-resistant control cable, comprising the following steps:

[0094] S1. Preparation of maleic anhydride modified polyethylene

[0095] Weigh out 60 parts of low-density polyethylene, 1 part of maleic anhydride and 0.2 parts of dicumyl peroxide as an initiator, and then add them to a twin-screw extruder. The temperatures of the six temperature sections of the twin-screw extruder from the feed end to the discharge end are 175° C., 180° C., 180° C., 180° C., 180° C. and 185° C., respectively. Adjust the main shaft speed of the twin-screw extruder, maintain melt mixing for 6 minutes, then extrude, cool and crush to obtain maleic anhydride-modified polyethylene.

[0096] S2. Preparation of modified polysiloxane

[0097] Weigh: 24.6 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, 216 mL of tetrahydrofuran, and 2.2 g of triethylamine are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is raised to 50° C. and stirred until the system is dissolved. 18.9 g of methyl-(3-isocyanatepropyl)dimethylsilane is added to the three-necked flask and the reaction is kept warm for 10 hours. The temperature of the three-necked flask is raised to 60° C. and low-boiling substances are evaporated under reduced pressure to obtain a modified flame retardant.

[0098] Weigh: 120 g of modified flame retardant, 900 g of octamethylcyclotetrasiloxane, 300 g of 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and 5000 mL of xylene are added to a reactor and stirred. The temperature of the reactor is raised to 120 ° C. 500 mL of 20 wt% formic acid aqueous solution is added to the reactor and kept warm for 6 h. 60 g of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, a capping agent, is added to the reactor and kept warm for 5 h. The temperature of the reactor is lowered to room temperature. 1 wt% sodium hydroxide solution is added to the reaction system to adjust the pH of the system to 7. The mixture is allowed to stand and separate. The organic phase is washed with purified water until neutral and then dried with anhydrous sodium sulfate for 6 h. Filtered, the organic phase is transferred to a rotary evaporator with a water bath temperature of 100 ° C. Low boiling substances are evaporated under reduced pressure to obtain polysiloxane;

[0099] Under an inert atmosphere, 500 g of polysiloxane and 5000 mL of xylene were weighed and added to a nitrogen-protected reactor with stirring. The temperature of the reactor was raised to 80° C., 100 g of isocyanate methyltrimethoxysilane was added to the reactor, and the reaction was kept warm for 80 minutes. The temperature of the reactor was raised to 100° C., and low-boiling substances were evaporated under reduced pressure to obtain modified polysiloxane.

[0100] S3. Preparation of loaded graphite

[0101] Weigh 30 g of aluminum chloride, 20 g of magnesium chloride, and 500 mL of 1.5 mol / L hydrochloric acid into a three-necked flask and stir until the system is dissolved. Add 150 g of expandable graphite to the three-necked flask and ultrasonically disperse for 60 min. Raise the temperature of the three-necked flask to 80°C and remove low-boiling substances under reduced pressure to obtain a supported graphite precursor.

[0102] The loaded graphite precursor and 5 mol / L sodium hydroxide solution were mixed at a ratio of 1 g:5 mL, stirred at room temperature for 50 min, filtered, and the filter cake was rinsed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 80°C and vacuum dried to constant weight to obtain loaded graphite.

[0103] S4. Preparation of modified graphite

[0104] Weigh: 120 g of loaded graphite and 1200 mL of 1 mol / L Tris-hydrochloride solution are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 80°C. 40 g of dopamine hydrochloride is added to the three-necked flask and the reaction is kept warm for 10 hours. The temperature of the three-necked flask is lowered to room temperature, and the mixture is filtered. The filter cake is washed three times with purified water and then dried. The filter cake is transferred to a drying oven at 80°C and dried under vacuum to a constant weight to obtain activated graphite.

[0105] Weigh: 120 g of activated graphite, 800 mL of ethanol and 40 g of KH-560 are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 60°C, 200 mL of 0.5 mol / L sodium hydroxide solution is added to the reaction system, and the reaction is kept warm for 65 minutes. The temperature of the three-necked flask is lowered to room temperature, filtered, and the filter cake is washed with purified water until neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified graphite.

[0106] S5. Preparation of cable materials

[0107] Magnesium stearate, diisopropyl phthalate, antioxidant CPPD, and ethylene bisstearamide are mixed uniformly in a weight ratio of 3:5:2:3 to obtain an auxiliary additive;

[0108] The following components were weighed in parts by weight: 90 parts of low-density polyethylene, 50 parts of maleic anhydride-modified polyethylene, 35 parts of modified polysiloxane, 19 parts of modified graphite, 3 parts of initiator dicumyl peroxide, and 5 parts of auxiliary additives, and mixed to obtain a cable material.

[0109] Example 4

[0110] See also Figure 1 This embodiment provides a method for preparing a Class B1 flame-retardant and fire-resistant control cable, comprising the following steps:

[0111] Step 1: Prepare the cable core

[0112] An oxygen-free copper conductor 101 is selected, cross-linked polyethylene is extruded and coated on the outside of the conductor 101 to form an insulating layer 102 on the outside of the conductor 101, a synthetic phlogopite tape is wrapped on the outside of the insulating layer 102 to form a fire-resistant layer 103 on the outside of the insulating layer 102, and a cable core 100 is obtained.

[0113] Step 2: Wrapping

[0114] Several cable cores 100 are arranged in parallel, and filling ropes are placed in the gaps between the cable cores 100 to form a filling layer 300 . The cable cores 100 filled with the filling layer 300 are wrapped together using a wrapping tape to form a wrapping layer 200 on the outside of the several cable cores 100 .

[0115] Step 3: Extrusion molding

[0116] The cable material prepared in Example 1 was added to a twin-screw extruder. The temperatures of the six temperature sections of the twin-screw extruder from the feed end to the discharge end were 175° C., 180° C., 180° C., 180° C., 180° C., and 185° C. The main shaft speed of the twin-screw extruder was adjusted to maintain melt mixing for 8 minutes. The material was then extruded and coated on the outside of the wrapping layer 200 to obtain a crude control cable.

[0117] The crude control cable is placed in a water vapor box at a temperature of 100° C. and subjected to heat preservation treatment for 8 hours. A sheath layer 400 is formed outside the wrapping layer 300 to obtain the control cable.

[0118] Example 5

[0119] See also Figure 1 This embodiment provides a method for preparing a Class B1 flame-retardant and fire-resistant control cable, comprising the following steps:

[0120] Step 1: Prepare the cable core

[0121] An oxygen-free copper conductor 101 is selected, cross-linked polyethylene is extruded and coated on the outside of the conductor 101 to form an insulating layer 102 on the outside of the conductor 101, a synthetic phlogopite tape is wrapped on the outside of the insulating layer 102 to form a fire-resistant layer 103 on the outside of the insulating layer 102, and a cable core 100 is obtained.

[0122] Step 2: Wrapping

[0123] Several cable cores 100 are arranged in parallel, and filling ropes are placed in the gaps between the cable cores 100 to form a filling layer 300 . The cable cores 100 filled with the filling layer 300 are wrapped together using a wrapping tape to form a wrapping layer 200 on the outside of the several cable cores 100 .

[0124] Step 3: Extrusion molding

[0125] The cable material prepared in Example 2 was added to a twin-screw extruder. The temperatures of the six temperature sections of the twin-screw extruder from the feed end to the discharge end were 175° C., 180° C., 180° C., 180° C., 180° C., and 185° C. The main shaft speed of the twin-screw extruder was adjusted to maintain melt mixing for 8 minutes. The material was then extruded and coated on the outside of the wrapping layer 200 to obtain a crude control cable.

[0126] The crude control cable is placed in a water vapor box at a temperature of 110° C. and subjected to heat preservation treatment for 7 hours, and a sheath layer 400 is formed outside the wrapping layer 300 to obtain the control cable.

[0127] Example 6

[0128] See also Figure 1 This embodiment provides a method for preparing a Class B1 flame-retardant and fire-resistant control cable, comprising the following steps:

[0129] Step 1: Prepare the cable core

[0130] An oxygen-free copper conductor 101 is selected, cross-linked polyethylene is extruded and coated on the outside of the conductor 101 to form an insulating layer 102 on the outside of the conductor 101, a synthetic phlogopite tape is wrapped on the outside of the insulating layer 102 to form a fire-resistant layer 103 on the outside of the insulating layer 102, and a cable core 100 is obtained.

[0131] Step 2: Wrapping

[0132] Several cable cores 100 are arranged in parallel, and filling ropes are placed in the gaps between the cable cores 100 to form a filling layer 300 . The cable cores 100 filled with the filling layer 300 are wrapped together using a wrapping tape to form a wrapping layer 200 on the outside of the several cable cores 100 .

[0133] Step 3: Extrusion molding

[0134] The cable material prepared in Example 3 was added to a twin-screw extruder. The temperatures of the six temperature sections of the twin-screw extruder from the feed end to the discharge end were 175° C., 180° C., 180° C., 180° C., 180° C., and 185° C. The main shaft speed of the twin-screw extruder was adjusted to maintain melt mixing for 8 minutes. The material was then extruded and coated on the outside of the wrapping layer 200 to obtain a crude control cable.

[0135] The crude control cable is placed in a water vapor box at a temperature of 120° C. and subjected to heat preservation treatment for 6 hours, and a sheath layer 400 is formed outside the wrapping layer 300 to obtain the control cable.

[0136] Comparative Example 1

[0137] The difference between this comparative example and Example 6 is that when the cable material prepared in Example 3 is used, no modified flame retardant is added during the preparation of polysiloxane in step S2.

[0138] Comparative Example 2

[0139] The difference between this comparative example and Example 6 is that when the cable material prepared in Example 3 is used, step S3 is omitted, and the supported graphite in step S4 is replaced by the expandable graphite in step S3.

[0140] Comparative Example 3

[0141] The difference between this comparative example and Example 6 is that when the cable material prepared in Example 3 is used, step S1 is omitted and maleic anhydride-modified polyethylene is not added in step S5.

[0142] Comparative Example 4

[0143] The difference between this comparative example and Example 6 is that when the cable material prepared in Example 3 is used, when preparing the modified graphite in step S4, the loaded graphite in step S3 is used instead of the activated graphite to prepare the modified graphite.

[0144] Performance testing:

[0145] The fire resistance of the control cable samples prepared in Examples 4-6 and Comparative Examples 1-3 was measured under the experimental conditions of 90 minutes of fire supply and 15 minutes of cooling with reference to the standard GB / T 19666-2019 "General Rules for Flame Retardant and Fire Resistant Wires, Cables or Optical Cables";

[0146] The tensile strength, elongation at break, and thermal shrinkage of the control cable samples prepared in Examples 4-6 and Comparative Examples 1-3 were measured with reference to Standard XF 306.1-2007 "Classification and requirements for flame retardant and fire resistant cables with plastic insulation Part 1: Flame retardant cables";

[0147] The flame retardancy levels of the control cable samples prepared in Examples 4-6 and Comparative Examples 1-3 were determined with reference to the standard GB 31247-2014 “Classification of Combustion Performance of Electrical and Optical Cables”. The specific test results are shown in Table 1.

[0148] Table 1-Performance test data of the sample

[0149] Group Project Tensile strength / MPa Elongation at break / % Flame retardant grade / level Fire resistance Example 4 15.8 205.5 B1 The fuse is blown and the indicator light does not go out Example 5 16.2 206.7 B1 The fuse is blown and the indicator light does not go out Example 6 15.9 205.8 B1 The fuse is blown and the indicator light does not go out Comparative Example 1 16.0 205.6 B2 The fuse is blown and the indicator light does not go out Comparative Example 2 16.1 206.1 B2 The fuse indicator light goes out Comparative Example 3 14.1 165.5 B1 The fuse is blown and the indicator light does not go out Comparative Example 4 15.8 204.5 B2 The fuse indicator light goes out

[0150] Data Analysis:

[0151] A comparative analysis of the data in the above table shows that the control cable prepared by the present invention has a tensile strength of the sheath layer of 16.2 MPa, an elongation at break of 206.7%, a flame retardant grade of B1, and good fire resistance stability. All performance parameters are superior to those of the comparative example, indicating that the present invention uses maleic anhydride-modified polyethylene as a phase solvent and cross-links and strengthens the polyethylene with modified graphite and improved polysiloxane, thereby effectively improving not only the mechanical strength of the cable material but also its fire resistance and flame retardant properties.

[0152] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a Class B1 flame retardant and fire resistant control cable, characterized in that: The following steps are involved: S1. Arrange a plurality of cable cores (100) in parallel, and fill a filling rope in the gap between the cable cores (100) to form a filling layer (300), and wrap the plurality of cable cores (100) filled with the filling layer (300) together using a wrapping tape to form a wrapping layer (200) on the outside of the plurality of cable cores (100), wherein the cable core (100) comprises a conductor (101), an insulating layer (102), and a fire-resistant layer (103) arranged in sequence from the inside to the outside, the conductor (101) is oxygen-free copper, the insulating layer (102) is obtained by wrapping cross-linked polyethylene on the outside of the conductor (101), and the fire-resistant layer (103) is obtained by wrapping a synthetic phlogopite tape on the outside of the insulating layer (102), and the filling rope is a low-smoke, halogen-free PP flame-retardant filling rope; S2, mixing low-density polyethylene, maleic anhydride-modified polyethylene, modified polysiloxane, modified graphite, initiator and auxiliary additives into a twin-screw extruder, melt-mixing for 8 minutes, and extruding and coating the mixture on the outside of the wrapping layer (200) to obtain a crude control cable, wherein the weight ratio of the low-density polyethylene, maleic anhydride-modified polyethylene, modified polysiloxane, modified graphite, initiator and auxiliary additives is 80-90:40-50:25-35:17-19:2-3:3-5, the initiator is diisopropylbenzene peroxide, and the auxiliary additives are composed of a dispersant, a plasticizer, an antioxidant and a lubricant in a weight ratio of 3:5:2:3; S3, placing the crude control cable product in a water vapor box at a temperature of 100-120° C., and heat-insulating the box for 6-8 hours, forming a sheath layer (400) outside the wrapping layer (200), and obtaining a control cable; Modified polysiloxane is processed by the following steps: A1. Mixing a modified flame retardant, octamethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and xylene, raising the temperature of the reaction system to 110-120° C., adding a catalyst to the reaction system, and keeping the temperature for 4-6 hours. Adding a capping agent to the reaction system, keeping the temperature for 3-5 hours, and post-treating to obtain polysiloxane; A2. Under an inert atmosphere, polysiloxane and xylene were mixed and stirred, the temperature of the reaction system was raised to 70-80°C, isocyanate methyltrimethoxysilane was added to the reaction system, and the reaction was kept warm for 60-80 minutes, and post-treated to obtain modified polysiloxane.

2. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 1, characterized in that: In step A1, the amount ratio of the modified flame retardant, octamethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, xylene, catalyst and end-capping agent is 0.8-1.2g:7-9g:2-3g:50mL:5mL:0.6g, the catalyst is a 20wt% formic acid aqueous solution, and the end-capping agent is 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane; in step A2, the amount ratio of the polysiloxane, xylene and isocyanate methyltrimethoxysilane is 5g:50mL:1g.

3. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 1, characterized in that: The modified flame retardant material is prepared by mixing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, tetrahydrofuran and triethylamine under an inert atmosphere, raising the temperature of the reaction system to 40-50° C., stirring until the system is dissolved, adding methyl-(3-isocyanatepropyl)dimethylsilane to the reaction system, keeping the temperature for reaction for 8-10 hours, and performing post-treatment to obtain the modified flame retardant material.

4. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 3, characterized in that: The molar ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide and methyl-(3-isocyanatepropyl)dimethylsilane is 1:1, and the usage ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, tetrahydrofuran and triethylamine is 1 g:10 mL:0.1 g.

5. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 1, characterized in that: The modified graphite is obtained by processing the following steps: B1. Mix and stir the loaded graphite and buffer solution, raise the temperature of the reaction system to 70-80°C, add dopamine hydrochloride to the reaction system, keep the temperature for 8-10 hours, and post-treat to obtain activated graphite; B2. Mix activated graphite, ethanol and KH-560, raise the temperature of the reaction system to 50-60°C, add alkali solution to the reaction system, keep the temperature and react for 55-65 minutes, and post-treat to obtain modified graphite.

6. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 5, characterized in that: In step B1, the ratio of the loaded graphite, buffer and dopamine hydrochloride is 3g:30mL:1g, and the buffer is a 1mol / L Tris-hydrochloride solution with a pH of 8.5; in step B2, the ratio of the activated graphite, ethanol, KH-560 and alkali solution is 3g:20mL:1g:5mL, and the alkali solution is a 0.3-0.5mol / L sodium hydroxide solution.

7. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 5, characterized in that: The supported graphite is processed by the following steps: C1. Mix aluminum chloride, magnesium chloride and dilute hydrochloric acid, stir until the system is dissolved, add expandable graphite to the reaction system, ultrasonically disperse for 40-60 minutes, and post-treat to obtain a loaded graphite precursor; C2. Add the supported graphite precursor into an alkaline solution, stir at room temperature for 30-50 minutes, and post-treat to obtain supported graphite.

8. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 7, characterized in that: In step C1, the aluminum chloride, magnesium chloride, dilute hydrochloric acid and expandable graphite are used in a ratio of 3g:2g:50mL:15g, and the concentration of the dilute hydrochloric acid is 0.8-1.5mol / L; in step C2, the supported graphite precursor and the alkaline solution are used in a ratio of 1g:5mL, and the alkaline solution is a 3-5mol / L sodium hydroxide solution.

Images