Preparation method of B1-grade flame-retardant fire-resistant control cable

Abstract

The invention discloses a preparation method of a B1-grade flame-retardant fire-resistant control cable, belongs to the technical field of flame-retardant fire-resistant cables, and aims to solve the technical problem that the mechanical strength and the fire-resistant and flame-retardant performance of an inorganic flame-retardant modified fire-resistant fire-resistant control cable in the prior art need to be further improved. The method comprises the following steps that a plurality of cable cores are arranged in parallel, gaps among the cable cores are filled with filling ropes to form filling layers, the cable cores filled with the filling layers are wrapped together through a wrapping tape, and a wrapping layer is formed outside the cable cores. According to the invention, maleic anhydride modified polyethylene is used as a phase solvent, and polyethylene is cross-linked and enhanced by modified graphite and modified polysiloxane, so that not only is the mechanical strength of the cable material effectively improved, but also the fire resistance and flame retardance of the cable material are improved.

Description

Technical Field

[0001] The 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 fire ranks first among all types of fires. 52% of the fires with clear causes are caused by electricity. Electrical fires are very harmful to society. Regulations and standards of 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 Cables" promulgated and implemented on September 1, 2015, modified and adopted EN50575 and EN13501-6 standards, and stipulated four classification standards: A, B1, B2, and B3. At present, in the design and construction of key places such as airports and subways with dense crowds of people and places that require 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 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 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 scheme: A method for preparing a B1-class flame-retardant and fire-resistant control cable comprises 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, and 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 mixture on the outside of the sheath to obtain a crude control cable;

[0009] S3. Place the crude control cable in a water vapor box at a temperature of 100-120°C for 6-8 hours of heat preservation 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 insulating layer and a fire-resistant layer arranged in sequence from the inside to the outside, the conductor is oxygen-free copper, the insulating 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 insulating layer, and the filling rope is a low-smoke halogen-free PP flame-retardant filling rope.

[0011] Further, 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 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. 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, 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, diisopropylbenzene 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. The free radicals then combine with each other to form maleic anhydride modifications on the low-density polyethylene molecular chains, 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] Further, the modified polysiloxane is processed by the following steps:

[0017] A1. The modified flame retardant, octamethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane and xylene are mixed, the temperature of the reaction system is raised to 110-120° C., a catalyst is added to the reaction system, and the reaction is carried out by heat preservation for 4-6 hours, a capping agent is added to the reaction system, and the reaction is carried out by heat preservation for 3-5 hours, and post-treatment is performed to obtain polysiloxane;

[0018] A2. In an inert atmosphere, polysiloxane and xylene are mixed and stirred, the temperature of the reaction system is raised to 70-80° C., isocyanate methyltrimethoxysilane is added to the reaction system, and the reaction is kept warm for 60-80 minutes, and post-processed 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, and then condensation occurs between the silanols 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 is then used as an active reaction site to undergo a condensation reaction with an isocyanate methyltrimethoxysilane molecule, and trimethoxysilane is modified on the polysiloxane chain 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 0.8-1.2 g:7-9 g:2-3 g:50 mL:5 mL:0.6 g, the catalyst is a 20 wt% 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 temperature of the reaction system 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 evaporated under reduced pressure to obtain polysiloxane; in step A2, the amount ratio of the polysiloxane, xylene and isocyanate methyltrimethoxysilane is 5g:50mL:1g, and the post-treatment includes: the temperature of the reaction system is increased to 90-100° C., and low boiling substances are evaporated under reduced pressure to obtain modified polysiloxane.

[0025] Furthermore, the preparation method of the modified flame retardant material is: in 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 material.

[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 hydroxyl group on the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide molecule is used as an active reaction site to undergo a condensation reaction with the isocyanate group on the methyl-(3-isocyanatopropyl)dimethylsilane molecule, and dimethoxysilane is modified on the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide molecule to prepare a modified flame retardant.

[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, the amount ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, tetrahydrofuran and triethylamine is 1g:10mL:0.1g, and the post-treatment comprises: after the reaction is completed, the temperature of the reaction system is increased to 50-60°C, and low boiling points are removed by distillation under reduced pressure to obtain a modified flame retardant.

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

[0033] B1, the loaded graphite and the buffer solution are mixed and stirred, the temperature of the reaction system is raised to 70-80°C, dopamine hydrochloride is added to the reaction system, the reaction is kept warm for 8-10 hours, and post-processed 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 for 55-65 minutes, and post-treat to obtain modified graphite.

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

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

[0037] Furthermore, in step B1, the amount ratio of the loaded graphite, the buffer and the 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 3 times and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80°C, and the weight is constant during vacuum drying to obtain activated graphite.

[0038] Furthermore, in step B2, the amount 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 it is neutral and then dried, 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] Further, 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 into the alkaline solution, stir for 30-50 minutes at room temperature, 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, and 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, while promoting the interaction between the metal ions and the graphite layer to form a supported graphite precursor. After the supported graphite precursor is mixed with a sodium hydroxide solution, the metal ions react with the hydroxide ions to generate corresponding magnesium and aluminum metal hydroxide precipitates or complexes that are retained in the interlayer structure of the graphite or 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 increased to 70-80°C, and low-boiling substances are evaporated under reduced pressure to obtain a supported graphite precursor; in step C2, the amount ratio of the supported graphite precursor and the alkaline solution is 1g:5mL, the alkaline solution is 3-5mol / L sodium hydroxide solution, and the post-treatment includes: after the reaction is completed, suction filtration, rinsing the filter cake with purified water until it is neutral and then draining it, transferring the filter cake to a drying oven at a temperature of 70-80°C, and vacuum drying it to constant weight to obtain supported 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 cloth tape is selected to wrap it to reduce the interference of the electromagnetic field on the conductor, and 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, the flame retardant performance of the cable material is improved, and by introducing active reaction sites on the constituent materials, the cross-linking between the 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 increases the reactivity and nitrogen content of 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, which separates the combustibles from the heat source and absorbs 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 down 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 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 segment body on the modified polysiloxane molecular chain and the phosphorus-containing compound modified on the segment are further coordinated 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 modified graphite in the sheath layer material by forming a polydopamine coating and epoxy modification on the modified graphite, and under a high temperature environment, the epoxy modified on the modified graphite particles can undergo ring-opening condensation with active groups such as amino groups and hydroxyl groups to promote intermolecular crosslinking, and enhance its polarity by modifying polyethylene with maleic anhydride. Through the mechanism of similar chain segments, the maleic anhydride-modified polyethylene can be evenly dispersed in the low-density polyethylene, making it easier for polyethylene to form hydrogen bonds with phosphorus-containing and olefin-modified polysiloxane segments, thereby enhancing the interaction between the two polymers, and under the action of an initiator, the unsaturated double bonds on the modified polysiloxane molecular chain are initiated to undergo free radical polymerization with polyethylene to form chemical bonds. At the same time, after high-temperature steam treatment, the siloxane bonds on the molecules can be promoted to hydrolyze and condense, further improving the degree of intermolecular crosslinking, 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 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 solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 is 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 0.6-0.8mm, a width of 900-1000mm, a breakdown strength of>15KV / mm, and a tensile strength of 2100N / 15mm;

[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 by weight: 60 parts of low-density polyethylene, 1 part of maleic anhydride and 0.2 parts of initiator dicumyl peroxide, mix them, and then add them into a twin-screw extruder. The temperatures of the 6 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, add them into a three-necked flask protected by nitrogen and stir, raise the temperature of the three-necked flask to 40°C, stir until the system is dissolved, add 18.9 g of methyl-(3-isocyanatepropyl)dimethylsilane into the three-necked flask, keep the temperature for 8 hours, raise the temperature of the three-necked flask to 50°C, and remove low-boiling substances under reduced pressure to obtain a modified flame retardant;

[0064] Weigh: 80g of modified flame retardant, 700g of octamethylcyclotetrasiloxane, 200g of 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and 5000mL of xylene, add to a reactor and stir, raise the temperature of the reactor to 110°C, add 500mL of 20wt% formic acid aqueous solution to the reactor, keep warm and react for 4h, add 60g of end-capping agent 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane to the reactor, keep warm and react for 3h, lower the temperature of the reactor to room temperature, add 1wt% sodium hydroxide solution to the reaction system, adjust the pH of the system to 7, stand and separate, wash the organic phase with purified water to neutrality, and then dry it with anhydrous sodium sulfate for 4h, filter, transfer the organic phase to a rotary evaporator with a water bath temperature of 90°C, and evaporate low boiling substances 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. The reaction was kept warm for 60 min. The temperature of the reactor was raised to 90° C. Low-boiling substances were evaporated under reduced pressure to obtain modified polysiloxane.

[0066] S3. Preparation of loaded graphite

[0067] Weigh: 30g aluminum chloride, 20g magnesium chloride and 500mL 0.8mol / L hydrochloric acid into a three-necked flask and stir until the system is dissolved. Add 150g expandable graphite into the three-necked flask and disperse by ultrasonic for 40min. Raise the temperature of the three-necked flask to 70°C and remove low boiling points 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, 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, and the filter cake is washed with purified water for 3 times and then dried. The filter cake is transferred to a drying oven at a temperature of 70° C. and the weight is constant during vacuum drying to obtain activated graphite;

[0071] Weigh: 120g of activated graphite, 800mL of ethanol and 40g of KH-560 are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 50°C. 200mL of 0.3mol / L sodium hydroxide solution is added to the reaction system. The reaction is kept warm for 55min. The temperature of the three-necked flask is lowered to room temperature, filtered, the filter cake is washed with purified water until it is neutral and then dried. The filter cake is 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] Weigh out 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 diisopropylbenzene peroxide and 3 parts of auxiliary additives, and mix 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 by weight: 60 parts of low-density polyethylene, 1 part of maleic anhydride and 0.2 parts of initiator dicumyl peroxide, mix them, and then add them into a twin-screw extruder. The temperatures of the 6 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 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, add them into a three-necked flask protected by nitrogen and stir, raise the temperature of the three-necked flask to 45° C., stir until the system is dissolved, add 18.9 g of methyl-(3-isocyanatepropyl)dimethylsilane into the three-necked flask, keep the temperature for 9 hours, raise the temperature of the three-necked flask to 50-60° C., remove low boiling substances under reduced pressure, and obtain a modified flame retardant;

[0081] Weigh: 100g of modified flame retardant, 800g of octamethylcyclotetrasiloxane, 250g of 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and 5000mL of xylene, add to a reactor and stir, raise the temperature of the reactor to 115°C, add 500mL of 20wt% formic acid aqueous solution to the reactor, keep warm and react for 5h, add 60g of end-capping agent 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane to the reactor, keep warm and react for 4h, lower the temperature of the reactor to room temperature, add 1wt% sodium hydroxide solution to the reaction system, adjust the pH of the system to 7, stand and separate, wash the organic phase with purified water to neutrality, and then dry it with anhydrous sodium sulfate for 5h, filter, transfer the organic phase to a rotary evaporator with a water bath temperature of 95°C, and evaporate low boiling substances 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. The reaction was kept warm for 70 min. The temperature of the reactor was raised to 95° C. Low-boiling substances were evaporated under reduced pressure to obtain modified polysiloxane.

[0083] S3. Preparation of loaded graphite

[0084] Weigh: 30g aluminum chloride, 20g magnesium chloride and 500mL 1.2mol / L hydrochloric acid into a three-necked flask and stir until the system is dissolved. Add 150g expandable graphite into the three-necked flask and disperse by ultrasonic for 50min. Raise the temperature of the three-necked flask to 75°C and remove low boiling points 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, 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. The reaction is kept warm for 9 hours. The temperature of the three-necked flask is lowered to room temperature. The filter cake is filtered and washed with purified water for 3 times and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and kept constant in vacuum drying to obtain activated graphite.

[0088] Weigh: 120g of activated graphite, 800mL of ethanol and 40g of KH-560 are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 55°C, 200mL of 0.4mol / L sodium hydroxide solution is added to the reaction system, and the reaction is kept warm for 60min. The temperature of the three-necked flask is lowered to room temperature, filtered, the filter cake is washed with purified water until it is neutral and then dried, and 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] Weigh out 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 mix 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 by weight: 60 parts of low-density polyethylene, 1 part of maleic anhydride and 0.2 parts of initiator dicumyl peroxide, mix them, and then add them into a twin-screw extruder. The temperatures of the 6 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, add them into a three-necked flask protected by nitrogen and stir, raise the temperature of the three-necked flask to 50° C., stir until the system is dissolved, add 18.9 g of methyl-(3-isocyanatepropyl)dimethylsilane into the three-necked flask, keep the temperature for 10 hours, raise the temperature of the three-necked flask to 60° C., remove low boiling substances under reduced pressure, and obtain a modified flame retardant;

[0098] Weigh: 120g of modified flame retardant, 900g of octamethylcyclotetrasiloxane, 300g of 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, and 5000mL of xylene, add to a reactor and stir, raise the temperature of the reactor to 120°C, add 500mL of 20wt% formic acid aqueous solution to the reactor, keep warm and react for 6h, add 60g of end-capping agent 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane to the reactor, keep warm and react for 5h, lower the temperature of the reactor to room temperature, add 1wt% sodium hydroxide solution to the reaction system, adjust the pH of the system to 7, stand and separate, wash the organic phase with purified water to neutrality, and then dry it with anhydrous sodium sulfate for 6h, filter, transfer the organic phase to a rotary evaporator with a water bath temperature of 100°C, and evaporate low boiling substances 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. The reaction was kept warm for 80 min. The temperature of the reactor was raised to 100° C. Low-boiling substances were evaporated under reduced pressure to obtain modified polysiloxane.

[0100] S3. Preparation of loaded graphite

[0101] Weigh: 30g aluminum chloride, 20g magnesium chloride and 500mL 1.5mol / L hydrochloric acid, add into a three-necked flask and stir until the system is dissolved, add 150g expandable graphite into the three-necked flask, ultrasonically disperse for 60min, raise the temperature of the three-necked flask to 80°C, and remove low boiling points 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, 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 filter cake is filtered, and the filter cake is washed with purified water for 3 times and then dried. The filter cake is transferred to a drying oven at a temperature of 80° C. and the weight is constant during vacuum drying to obtain activated graphite;

[0105] Weigh: 120g of activated graphite, 800mL of ethanol and 40g of KH-560 are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 60°C, 200mL of 0.5mol / L sodium hydroxide solution is added to the reaction system, and the reaction is kept warm for 65min. The temperature of the three-necked flask is lowered to room temperature, filtered, the filter cake is washed with purified water until it is neutral and then dried, and 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 uniformly mixed in a weight ratio of 3:5:2:3 to obtain an auxiliary additive;

[0108] Weigh out 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 diisopropylbenzene peroxide and 5 parts of auxiliary additives, and mix to obtain a cable material.

[0109] Example 4

[0110] See also Figure 1 The present 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, and 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 to obtain a cable core 100.

[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 several cable cores 100 filled with the filling layer 300 are wrapped together using a wrapping tape to form a wrapping layer 200 outside 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, and 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., respectively. The main shaft speed of the twin-screw extruder was adjusted to maintain melt mixing for 8 minutes, and the material was 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, and a sheath layer 400 is formed outside the wrapping layer 300 to obtain the control cable.

[0118] Example 5

[0119] See also Figure 1 The present 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, and 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 to obtain a cable core 100.

[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 several cable cores 100 filled with the filling layer 300 are wrapped together using a wrapping tape to form a wrapping layer 200 outside 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, and 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., respectively. The main shaft speed of the twin-screw extruder was adjusted to maintain melt mixing for 8 minutes, and the material was 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, and 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 to obtain a cable core 100.

[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 several cable cores 100 filled with the filling layer 300 are wrapped together using a wrapping tape to form a wrapping layer 200 outside 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, and 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., respectively. The main shaft speed of the twin-screw extruder was adjusted to maintain melt mixing for 8 minutes, and the material was 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 when preparing 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 by 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 by 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 by Example 3 is used, when preparing 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 under the experimental conditions of 90 min fire supply + 15 min cooling was determined 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, plastic insulated flame retardant and fire resistant cables, Part 1: Flame retardant cables";

[0147] The flame retardant 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 Cables 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 Fuse blown 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 Fuse blown 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 16.2 MPa and an elongation at break of 206.7% for the sheath layer, and the flame retardant grade of the control cable reaches B1, and has good fire resistance stability, and all performance parameters are better than those of the comparative example, indicating that the present invention uses maleic anhydride-modified polyethylene as a phase solvent and cross-links and strengthens polyethylene with modified graphite and improved polysiloxane, which not only effectively improves the mechanical strength of the cable material, but also improves its fire resistance and flame retardant properties.

[0152] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a B1-class 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 the gaps between the cable cores (100) with filling ropes 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) outside the plurality of cable cores (100); 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; S3. Place the crude control cable 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 (400) outside the wrapping layer (300) to obtain a control cable.

2. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 1, characterized in that: In step S1, the cable core (100) comprises a conductor (101), an insulating layer (102) and a fire-resistant layer (103) which are arranged in sequence from the inside to the outside, the conductor (101) is oxygen-free copper, the insulating layer (102) is obtained by coating the outside of the conductor (101) with cross-linked polyethylene, the fire-resistant layer (103) is obtained by wrapping a synthetic phlogopite tape around the outside of the insulating layer (102), and the filling rope is a low-smoke halogen-free PP flame-retardant filling rope; 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 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.

3. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 1, characterized in that: The modified polysiloxane is processed by the following steps: A1. The modified flame retardant, octamethylcyclotetrasiloxane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane and xylene are mixed, the temperature of the reaction system is raised to 110-120° C., a catalyst is added to the reaction system, and the reaction is carried out by heat preservation for 4-6 hours, a capping agent is added to the reaction system, and the reaction is carried out by heat preservation for 3-5 hours, and post-treatment is performed to obtain polysiloxane; A2. In an inert atmosphere, polysiloxane and xylene are mixed and stirred, the temperature of the reaction system is raised to 70-80° C., isocyanate methyltrimethoxysilane is added to the reaction system, and the reaction is kept warm for 60-80 minutes, and post-processed to obtain modified polysiloxane.

4. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 3, 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.

5. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 3, characterized in that: The preparation method of the modified flame retardant material comprises: 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 post-treating to obtain the modified flame retardant material.

6. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 5, 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 amount ratio of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methanol-10-oxide, tetrahydrofuran and triethylamine is 1g:10mL:0.1g.

7. 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, the loaded graphite and the buffer solution are mixed and stirred, the temperature of the reaction system is raised to 70-80°C, dopamine hydrochloride is added to the reaction system, the reaction is kept warm for 8-10 hours, and post-processed 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 for 55-65 minutes, and post-treat to obtain modified 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 B1, the amount ratio of the loaded graphite, the buffer and the 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 amount ratio of the activated graphite, ethanol, KH-560 and the alkali solution is 3g:20mL:1g:5mL, and the alkali solution is a 0.3-0.5mol / L sodium hydroxide solution.

9. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 7, 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 for 30-50 minutes at room temperature, and post-treat to obtain supported graphite.

10. The method for preparing a Class B1 flame retardant and fire resistant control cable according to claim 9, characterized in that: In step C1, the dosage ratio of the aluminum chloride, magnesium chloride, dilute hydrochloric acid and expandable graphite is 3g:2g:50mL:15g, and the concentration of the dilute hydrochloric acid is 0.8-1.5mol / L; in step C2, the dosage ratio of the supported graphite precursor and the alkaline solution is 1g:5mL, and the alkaline solution is 3-5mol / L sodium hydroxide solution.

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