Self-extinguishing cable and preparation method thereof

Abstract

The invention relates to the field of cables, in particular to a self-extinguishing cable and a preparation method thereof. The invention provides a self-extinguishing cable. The self-extinguishing cable comprises a plurality of wire cores and a wear-resistant outer sheath coating the plurality of wire cores, fire extinguishing cotton is filled between the plurality of wire cores and the wear-resistant outer sheath. The fire extinguishing cotton comprises the following raw materials in parts by weight: 50-70 parts of a dry powder extinguishing agent and 80-100 parts of ethylene propylene diene monomer. The fire-extinguishing cotton is light in material and good in insulation effect, can keep the roundness of the cable as a filling material, is firm and stable in structure and good in toughness, and effectively prolongs the service life of the cable. When the cable is short-circuited to generate huge current to cause the cable to be on fire and cause combustion, the fire extinguishing cotton can be combusted to release particles of the internal dry powder fire extinguishing agent, the particles are dense and fine in concentration and cover the insulating surface of the cable to form an isolating layer for hindering combustion, and meanwhile, non-combustible gas is separated out, so that the oxygen concentration in the air is reduced, and the flame is extinguished.

Description

Technical Field

[0001] The invention relates to the field of cables, and in particular to a self-fire extinguishing cable and a preparation method thereof. Background Art

[0002] According to Chinese fire data, from January to October 2023, a total of 745,000 fires were reported nationwide, resulting in 1,381 deaths, 2,063 injuries, and direct property losses of 6.15 billion yuan. Compared with the same period last year, the number of fires and the number of injured increased by 2.5% and 6.5% respectively, and electricity was the primary cause of fire. Therefore, electrical safety remains the top priority of fire prevention awareness, and short-circuit fires in wires and cables are still a key point of prevention that cannot be ignored.

[0003] Most of the power cables on the market currently require flame retardancy as a characteristic, but flame retardant cables only prevent the spread of flames after the cable catches fire, and cannot prevent the occurrence of fire. In the later stage of a fire, it mainly causes the combustion of other combustibles, which eventually leads to a larger fire. The early stage of a fire is the golden period for extinguishing a fire. Ordinary flame retardant power cables are difficult to detect in the early stages of a fire due to the laying environment, use conditions and other reasons. In the prior art, the coating, the total protective layer and the outer sheath are improved, and flame retardant material components are developed and added to the coating. The "self-extinguishing cable" disclosed in Chinese Patent 202210791461.X reduces the fire or extinguishes the flame through the CO2 in the cable.

[0004] However, the method of filling the cable with CO2 reduces the toughness of the cable, places high requirements on the storage of the cable, and shortens the service life of the cable. Summary of the invention

[0005] The present invention aims to overcome the above problems existing in the prior art and provides a self-fire extinguishing cable and a preparation method thereof. Fire extinguishing cotton is used as the filling material. The cable has a firm and stable structure and good toughness, and its service life is effectively extended.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a self-fire extinguishing cable, comprising: A plurality of wire cores and an anti-wear outer sheath covering the plurality of wire cores; fire extinguishing cotton is filled between the plurality of wire cores and the anti-wear outer sheath; The raw materials of the fire extinguishing cotton include the following components in parts by weight: 50-70 parts of dry powder fire extinguishing agent and 80-100 parts of EPDM rubber.

[0007] Fire extinguishing cotton is light in material and has good insulation effect. As a filling material, it can keep the cable round, and the cable structure is firm, stable and tough. When a cable short circuit generates a huge current, causing the cable to catch fire and burn, the fire extinguishing cotton will burn and release the particles of dry powder fire extinguishing agent inside. The particles are dense and fine, covering the surface of the cable insulation to form an isolation layer that hinders combustion, and at the same time, non-combustible gas is precipitated to reduce the oxygen concentration in the air and extinguish the flame.

[0008] Preferably, the preparation method of the dry powder fire extinguishing agent comprises the following steps: Weigh 100-120 parts of fire extinguishing base material, 5-10 parts of lubricant, and 3-5 parts of moisture-proof agent according to the weight of the constituent raw materials; grind and add 30-40 parts of fluorocarbon alkylamine, heat to 80-90°C, keep warm and stir, and vacuum dry; then add 15-30 parts of carbon nanotubes The product is subjected to high-speed ball milling and passed through a 400-500 mesh sieve to obtain a dry powder fire extinguishing agent.

[0009] In the above technical solution, the carbon nanotubes are co-grinded with the fire extinguishing base material, which greatly enhances the dispersibility of the dry powder fire extinguishing agent and also helps the subsequent interaction between the dry powder fire extinguishing agent and the EPDM rubber in the fire extinguishing cotton. Fluorocarbon alkylamine is a surfactant that mainly plays the role of reducing surface tension, enhancing dispersibility and stability, and can form a thin film on the surface of the dry powder fire extinguishing agent to enhance the compatibility and dispersibility of the dry powder fire extinguishing agent. Fluorocarbon alkylamine helps the dry powder fire extinguishing agent to be more evenly dispersed in the EPDM rubber instead of directly causing obvious cross-linking or grafting reactions with the rubber.

[0010] Preferably, the method for preparing the fire extinguishing cotton comprises the following steps: (S1) adding 10 to 15 parts of dry powder fire extinguishing agent to 80 to 100 parts of EPDM rubber, stirring at a low speed at 80 to 100° C. for 3 to 5 minutes to make the mixture uniform, cooling to room temperature, adding to an open mill, controlling the temperature at 150 to 180° C. for foaming, granulating, and obtaining EPDM rubber sponge; (S2) adding 30 to 55 parts of dry powder fire extinguishing agent to the EPDM rubber sponge obtained in (S1), stirring at a low speed for 3 to 5 minutes at 80 to 100° C. to make the mixture uniform, and cooling to room temperature to obtain a finished product.

[0011] The foamed product obtained in step (S1) is EPDM rubber sponge, which has good heat resistance and flame retardancy. In addition, no additional foaming agent needs to be added in the above reaction, because the fluorocarbon alkylamine in the dry powder fire extinguishing agent as an organic foaming agent and the fire extinguishing base as an inorganic foaming agent react with the EPDM rubber to release gas, thereby forming bubbles, and obtaining EPDM rubber sponge with ideal properties.

[0012] In step (S2), the dry powder fire extinguishing agent is blended with EPDM rubber sponge. Since the carbon nanotubes are grafted with the EPDM rubber sponge, the dry powder fire extinguishing agent is more evenly dispersed in the EPDM rubber, thereby improving the compatibility and interaction between the dry powder fire extinguishing agent and the EPDM rubber. When subjected to high-temperature combustion, the dry powder fire extinguishing agent particles uniformly distributed inside are quickly released to hinder the burning of the cable. Based on theoretical research and experiments, the team of the present invention found that the temperature of the grafting reaction is preferably controlled at 80 to 100°C. When the reaction temperature is greater than 100°C, by-products will be produced. It is speculated that the reason is that the temperature is too high, resulting in intermolecular condensation, side reactions, impurities, and the accidental release of dry powder fire extinguishing agent particles. Based on this, the present invention controls the temperature of the reaction at 80 to 100°C, which can accelerate the rate of the grafting reaction.

[0013] Preferably, the carbon nanotubes are carbonyl-modified carbon nanotubes, and the preparation method comprises the following steps: Weigh the carbon nanotube raw material and put it into a high-temperature furnace, evacuate the high-temperature furnace to less than or equal to -0.09MPa, introduce inert gas into the high-temperature furnace until the pressure in the high-temperature furnace is greater than the standard atmospheric pressure and the purity of the inert gas in the high-temperature furnace is greater than or equal to 98%, open the gas outlet of the high-temperature furnace to keep the inert gas flowing; heat the high-temperature furnace to 800-1000°C; stop inputting the inert gas, and input oxygen into the high-temperature furnace, the flow rate of the oxygen is 500-600mL / min; keep the high-temperature furnace warm until carbonyl-modified carbon nanotubes are formed.

[0014] Oxygen will react with the surface of carbon nanotubes to introduce carbonyl functional groups on the surface of carbon nanotubes. Carbonyl functional groups have strong electrophilicity and can react chemically with EPDM rubber containing nucleophilic functional groups to form covalent bonds, thereby achieving grafting. After grafting, a strong bond is formed between carbon nanotubes and EPDM rubber, thereby enhancing the compatibility and bonding ability of carbon nanotubes and EPDM rubber, and also helping to improve the mechanical properties of the composite material.

[0015] Preferably, the fire extinguishing base material is one or more of sodium bicarbonate, sodium carbonate, ammonium carbonate, and ammonium phosphate; the lubricant is one or more of magnesium stearate, mica powder, and talcum powder; The moisture-proof agent is silica gel.

[0016] Preferably, the number of the wire cores is 3, and the 3 wire cores are distributed in a triangle. When the 3 wire cores are closed, a space is left in the middle, and the space is filled with nitrogen.

[0017] The space between the closed wire cores is filled with inert gas, which helps to release the fire extinguishing particles; and the release of inert gas can reduce the oxygen content at the fire point and play a flame retardant role.

[0018] Preferably, each wire core comprises a twisted conductor and an insulation layer.

[0019] Preferably, the wear-resistant outer protective layer is formed by extruding halogen-free, low-smoke, flame-retardant polyolefin insulation material.

[0020] Halogen-free, low-smoke, flame-retardant polyolefin is used as the sheath material to cover the surface of the cable core and has a good protective effect.

[0021] Preferably, a fire extinguishing inner protective layer is further provided on the inner side of the wear-resistant outer protective layer, and the preparation method of the fire extinguishing inner protective layer is to make the fire extinguishing cotton into a strip shape to form a cable wrapping tape.

[0022] In a second aspect, the present invention provides a method for preparing the above-mentioned self-fire extinguishing cable, comprising the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 and 2.8 mm, the extrusion temperature is 150 to 180°C, and the screw speed is controlled at 20 to 30 r / min; obtaining a wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outer side of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 150-180°C and made into a strip shape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: Extruding the wear-resistant outer sheath on the outer side of the fire-extinguishing inner sheath, the extrusion temperature is 150-180°C, and the screw speed is controlled at 10-20r / min to obtain a self-extinguishing cable.

[0023] The beneficial effects of the present invention are: (1) The self-extinguishing cable of the present invention uses fire extinguishing cotton as a filling material. The cable has a firm and stable structure and effectively extends its service life. When a cable short circuit generates a huge current, causing the cable to catch fire and burn, the fire extinguishing cotton will burn and release the particles of the internal dry powder fire extinguishing agent, which can reduce the incidence of fire. (2) The fire extinguishing cotton of the present invention uses EPDM rubber as a matrix, and its grafting reaction with carbon nanotubes makes the dry powder fire extinguishing agent more evenly dispersed in the EPDM rubber, thereby improving the compatibility and interaction between the dry powder fire extinguishing agent and the EPDM rubber, which makes the fire extinguishing cotton suitable for filling self-extinguishing cables; (3) Based on theoretical research and experiments, the present invention team found that the temperature of the grafting reaction is best controlled at 80-100°C, which can accelerate the rate of the grafting reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1The structure diagram of the self-extinguishing cable of the embodiment of the present invention is shown in FIG. 1 is a conductor, 2 is an insulating layer, 3 is a fire extinguishing cotton, 4 is a fire extinguishing inner sheath, and 5 is an anti-wear outer sheath. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the technical solution embodiment of the present invention clearer, the technical solution of the embodiment of the present invention is clearly explained and illustrated in conjunction with the accompanying drawings below, but the following embodiments are only preferred embodiments of the present invention, rather than all embodiments. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without making creative work are all within the scope of protection of the present invention.

[0026] Overall embodiment A self-fire extinguishing cable, comprising: A plurality of wire cores and an anti-wear outer sheath covering the plurality of wire cores; fire extinguishing cotton is filled between the plurality of wire cores and the anti-wear outer sheath; The raw materials of the fire extinguishing cotton include the following components in parts by weight: 50-70 parts of dry powder fire extinguishing agent and 80-100 parts of EPDM rubber.

[0027] Preferably, the preparation method of the dry powder fire extinguishing agent comprises the following steps: Weigh 100-120 parts of fire extinguishing base material, 5-10 parts of lubricant, and 3-5 parts of moisture-proof agent according to the weight of the constituent raw materials; grind and add 30-40 parts of fluorocarbon alkylamine, heat to 80-90°C, keep warm and stir, and vacuum dry; then add 15-30 parts of carbon nanotubes The product is subjected to high-speed ball milling and passed through a 400-500 mesh sieve to obtain a dry powder fire extinguishing agent.

[0028] Preferably, the method for preparing the fire extinguishing cotton comprises the following steps: (S1) adding 10 to 15 parts of dry powder fire extinguishing agent to 80 to 100 parts of EPDM rubber, stirring at a low speed at 80 to 100° C. for 3 to 5 minutes to make the mixture uniform, cooling to room temperature, adding to an open mill, controlling the temperature at 150 to 180° C. for foaming, granulating, and obtaining EPDM rubber sponge; (S2) adding 30 to 55 parts of dry powder fire extinguishing agent to the EPDM rubber sponge obtained in (S1), stirring at a low speed for 3 to 5 minutes at 80 to 100° C. to make the mixture uniform, and cooling to room temperature to obtain a finished product.

[0029] Preferably, the carbon nanotubes are carbonyl-modified carbon nanotubes, and the preparation method comprises the following steps: Weigh the carbon nanotube raw material and put it into a high-temperature furnace, evacuate the high-temperature furnace to less than or equal to -0.09MPa, introduce inert gas into the high-temperature furnace until the pressure in the high-temperature furnace is greater than the standard atmospheric pressure and the purity of the inert gas in the high-temperature furnace is greater than or equal to 98%, open the gas outlet of the high-temperature furnace to keep the inert gas flowing; heat the high-temperature furnace to 800-1000°C; stop inputting the inert gas, and input oxygen into the high-temperature furnace, the flow rate of the oxygen is 500-600mL / min; keep the high-temperature furnace warm until carbonyl-modified carbon nanotubes are formed.

[0030] Preferably, the fire extinguishing base material is one or more of sodium bicarbonate, sodium carbonate, ammonium carbonate, and ammonium phosphate; the lubricant is one or more of magnesium stearate, mica powder, and talcum powder; The moisture-proof agent is silica gel.

[0031] Preferably, the number of the wire cores is 3, and the 3 wire cores are distributed in a triangle. When the 3 wire cores are closed, a space is left in the middle, and the space is filled with nitrogen.

[0032] Preferably, each wire core comprises a twisted conductor and an insulation layer.

[0033] Preferably, the wear-resistant outer protective layer is formed by extruding halogen-free, low-smoke, flame-retardant polyolefin insulation material.

[0034] Preferably, a fire extinguishing inner protective layer is further provided on the inner side of the wear-resistant outer protective layer, and the preparation method of the fire extinguishing inner protective layer is to make the fire extinguishing cotton into a strip shape to form a cable wrapping tape.

[0035] A method for preparing the above-mentioned self-fire extinguishing cable comprises the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 and 2.8 mm, the extrusion temperature is 150 to 180°C, and the screw speed is controlled at 20 to 30 r / min; obtaining a wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outer side of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 150-180°C and made into a strip shape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: Extruding the wear-resistant outer sheath on the outer side of the fire-extinguishing inner sheath, the extrusion temperature is 150-180°C, and the screw speed is controlled at 10-20r / min to obtain a self-extinguishing cable.

[0036] Example 1 Carbonyl-modified carbon nanotubes are prepared by the following steps: weighing carbon nanotube raw materials and placing them in a high-temperature furnace, evacuating the high-temperature furnace to -0.09MPa, introducing nitrogen into the high-temperature furnace until the pressure in the high-temperature furnace is greater than the standard atmospheric pressure and the purity of the inert gas in the high-temperature furnace is greater than or equal to 98%, opening the gas outlet of the high-temperature furnace to keep the inert gas flowing; heating the high-temperature furnace to 800°C; stopping the input of nitrogen, and inputting oxygen into the high-temperature furnace, the flow rate of the oxygen is 500mL / min; keeping the high-temperature furnace warm until carbonyl-modified carbon nanotubes are formed. The carbon nanotubes selected in this embodiment are multi-walled carbon nanotubes, with an inner diameter of 3nm, an outer diameter of 8nm, a length of 3μm, 8 tube wall layers, and an aspect ratio of 230.

[0037] Example 2 Carbonyl-modified carbon nanotubes are prepared by the following steps: Weigh the carbon nanotube raw material and put it into a high-temperature furnace, evacuate the high-temperature furnace to -0.10MPa, introduce nitrogen into the high-temperature furnace until the pressure in the high-temperature furnace is greater than the standard atmospheric pressure and the purity of the inert gas in the high-temperature furnace is greater than or equal to 98%, open the gas outlet of the high-temperature furnace, and keep the inert gas flowing; heat the high-temperature furnace to 1000℃; stop inputting nitrogen, and input oxygen into the high-temperature furnace, the flow rate of the oxygen is 600mL / min; keep the high-temperature furnace warm until carbonyl-modified carbon nanotubes are formed. The carbon nanotubes selected in this embodiment have an inner diameter of 5nm, an outer diameter of 15nm, and a length of 20μm.

[0038] Example 3 Dry powder fire extinguishing agent is made by the following steps: Weigh a fire extinguishing base material, a lubricant and a moisture-proof agent, grind them, add a fluorocarbon alkylamine, heat to 80°C, keep warm and stir, and vacuum dry; then add the carbon nanotubes prepared in Example 1 and perform high-speed ball milling, pass through a 400-mesh sieve to obtain a dry powder fire extinguishing agent; the fire extinguishing base material is a mixture of sodium bicarbonate and sodium carbonate, the lubricant is magnesium stearate, and the moisture-proof agent is silica gel; the weight parts of each component raw material are shown in Table 1.

[0039] Example 4 Dry powder fire extinguishing agent is made by the following steps: Weigh a fire extinguishing base material, a lubricant and a moisture-proof agent, grind them, add a fluorocarbon alkylamine, heat to 90° C., keep warm and stir, and vacuum dry; then add the carbon nanotubes prepared in Example 2 and perform high-speed ball milling, pass through a 500-mesh sieve, and obtain a dry powder fire extinguishing agent; the fire extinguishing base material is ammonium phosphate, the lubricant is a mixture of mica powder and talcum powder, and the moisture-proof agent is silica gel. The weight parts of each component raw material are shown in Table 1.

[0040] Comparative Example 1 Dry powder fire extinguishing agent is made by the following steps: The fire extinguishing base material, lubricant and moisture-proof agent are weighed and ground, and fluorocarbon alkylamine is added, the temperature is raised to 90° C., the mixture is stirred at the temperature, and vacuum dried; unmodified carbon nanotubes are added and high-speed ball milling is performed, and the mixture is sieved through a 500-mesh sieve to obtain a dry powder fire extinguishing agent; the fire extinguishing base material is ammonium phosphate, the lubricant is a mixture of mica powder and talcum powder, and the moisture-proof agent is silica gel. The weight parts of each component raw material are shown in Table 1.

[0041] Example 5 Dry powder fire extinguishing agent is made by the following steps: Weigh a fire extinguishing base material, a lubricant and a moisture-proof agent, grind them, add a fluorocarbon alkylamine, heat to 90° C., keep warm and stir, and vacuum dry; then add the carbon nanotubes prepared in Example 1 and perform high-speed ball milling, pass through a 500-mesh sieve, and obtain a dry powder fire extinguishing agent; the fire extinguishing base material is ammonium carbonate, the lubricant is a mixture of mica powder and talcum powder, and the moisture-proof agent is silica gel. The weight parts of each component raw material are shown in Table 1.

[0042] Comparative Example 2 Dry powder fire extinguishing agent is made by the following steps: Weigh a fire extinguishing base material, a lubricant and a moisture-proof agent, grind them, add a fluorocarbon alkylamine, heat to 90° C., keep warm and stir, and vacuum dry; then add the carbon nanotubes prepared in Example 1 and perform high-speed ball milling, pass through a 500-mesh sieve, and obtain a dry powder fire extinguishing agent; the fire extinguishing base material is ammonium phosphate, the lubricant is a mixture of mica powder and talcum powder, and the moisture-proof agent is silica gel. The weight parts of each component raw material are shown in Table 1.

[0043] Table 1 Raw material composition of dry powder fire extinguishing agent Fire extinguishing base Lubricants Moisture-proofing agent Fluorocarbon alkylamine Carbon Nanotubes Example 3 100 10 5 40 30 Example 4 120 5 3 30 27 Comparative Example 1 120 5 3 30 27 Example 5 120 5 5 40 15 Comparative Example 2 120 10 5 40 5 Example 6 Fire extinguishing cotton is made by the following steps: (S1) adding the dry powder fire extinguishing agent prepared in Example 4 to EPDM rubber, stirring at a low speed for 3 minutes at 80° C. to make the mixture uniform, cooling to room temperature, adding to an open mixer, controlling the temperature at 150° C. to foam, granulate, and obtain EPDM rubber sponge; (S2) Add the dry powder fire extinguishing agent prepared in Example 4 to the EPDM rubber sponge prepared in (S1), stir at a low speed for 3 minutes at 80° C. to make the mixture uniform, and cool to room temperature to obtain a finished product; the weight parts of each component raw material are shown in Table 2.

[0044] Comparative Example 3 Fire extinguishing cotton is made by the following steps: (S1) adding the dry powder fire extinguishing agent prepared in Comparative Example 1 to EPDM rubber, stirring at a low speed for 3 minutes at 80° C. to make the mixture uniform, cooling to room temperature, adding to an open mixer, controlling the temperature at 150° C. to foam, granulate, and obtain EPDM rubber sponge; (S2) Add the dry powder fire extinguishing agent prepared in Comparative Example 1 to the EPDM rubber sponge prepared in (S1), stir at a low speed for 3 minutes at 80° C. to make the mixture uniform, and cool to room temperature to obtain a finished product; the weight parts of each component raw material are shown in Table 2.

[0045] Comparative Example 4 Fire extinguishing cotton is made by the following steps: (S1) adding the dry powder fire extinguishing agent prepared in Comparative Example 2 to EPDM rubber, stirring at a low speed for 3 minutes at 80° C. to make the mixture uniform, cooling to room temperature, adding to an open mixer, controlling the temperature at 150° C. to foam, granulate, and obtain EPDM rubber sponge; (S2) Add the dry powder fire extinguishing agent prepared in Comparative Example 2 to the EPDM rubber sponge prepared in (S1), stir at a low speed for 3 minutes at 80° C. to make the mixture uniform, and cool to room temperature to obtain a finished product; the weight parts of each component raw material are shown in Table 2.

[0046] Example 7 Fire extinguishing cotton is made by the following steps: (S1) adding the dry powder fire extinguishing agent prepared in Example 4 to EPDM rubber, stirring at a low speed for 5 minutes at 100° C. to make the mixture uniform, cooling to room temperature, adding to an open mixer, controlling the temperature at 180° C. to foam, granulate, and obtain EPDM rubber sponge; (S2) Add the dry powder fire extinguishing agent prepared in Example 4 to the EPDM rubber sponge prepared in (S1), stir at a low speed for 3 minutes at 100° C. to ensure uniform mixing, and cool to room temperature to obtain a finished product; the weight parts of each component raw material are shown in Table 2.

[0047] Comparative Example 5 Fire extinguishing cotton is made by the following steps: (S1) adding the dry powder fire extinguishing agent prepared in Example 4 to EPDM rubber, stirring at a low speed at 120° C. for 5 minutes to make the mixture uniform, cooling to room temperature, adding to an open mixer, controlling the temperature at 180° C. for foaming, granulating, and obtaining EPDM rubber sponge; (S2) Add the dry powder fire extinguishing agent prepared in Example 4 to the EPDM rubber sponge prepared in (S1), stir at a low speed for 3 minutes at 120° C. to make the mixture uniform, and cool to room temperature to obtain a finished product; the weight parts of each component raw material are shown in Table 2.

[0048] Example 8 Fire extinguishing cotton is made by the following steps: (S1) adding the dry powder fire extinguishing agent prepared in Example 4 to EPDM rubber, stirring at a low speed for 3 minutes at 80° C. to make the mixture uniform, cooling to room temperature, adding to an open mixer, controlling the temperature at 150° C. to foam, granulate, and obtain EPDM rubber sponge; (S2) Add the dry powder fire extinguishing agent prepared in Example 4 to the EPDM rubber sponge prepared in (S1), stir at a low speed for 5 minutes at 80° C. to make the mixture uniform, and cool to room temperature to obtain a finished product; the weight parts of each component raw material are shown in Table 2.

[0049] Table 2 Raw material composition of fire extinguishing cotton Example 9 like Figure 1 A self-fire extinguishing cable is shown, comprising: 3 wire cores; the 3 wire cores are distributed in a triangle shape, and a space is left in the middle when the 3 wire cores are closed, and the space is filled with nitrogen; each wire core includes a twisted conductor and an insulating layer; An anti-wear outer sheath is coated on the outside of the three wire cores; the anti-wear outer sheath is extruded from halogen-free, low-smoke, flame-retardant polyolefin insulation material; the fire extinguishing cotton prepared in Example 7 is filled between the three wire cores and the anti-wear outer sheath.

[0050] The self-extinguishing cable is made by the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 mm, the extrusion temperature is 150°C, and the screw speed is controlled at 20 r / min; obtaining the wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outside of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 180°C, and the strip is made into a cable wrapping tape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: The wear-resistant outer sheath is extruded on the outer side of the fire-extinguishing inner sheath at an extrusion temperature of 180°C and a screw speed of 10 r / min to obtain a self-extinguishing cable.

[0051] Comparative Example 6 like Figure 1 A self-fire extinguishing cable is shown, comprising: 3 wire cores; the 3 wire cores are distributed in a triangle shape, and a space is left in the middle when the 3 wire cores are closed, and the space is filled with nitrogen; each wire core includes a twisted conductor and an insulating layer; An anti-wear outer sheath is coated on the outside of the three wire cores; the anti-wear outer sheath is extruded from halogen-free, low-smoke, flame-retardant polyolefin insulation material; the fire extinguishing cotton prepared in Comparative Example 3 is filled between the three wire cores and the anti-wear outer sheath.

[0052] The self-extinguishing cable is made by the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 mm, the extrusion temperature is 150°C, and the screw speed is controlled at 20 r / min; obtaining the wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outside of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 180°C, and the strip is made into a cable wrapping tape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: The wear-resistant outer sheath is extruded on the outer side of the fire-extinguishing inner sheath at an extrusion temperature of 180°C and a screw speed of 10 r / min to obtain a self-extinguishing cable.

[0053] Comparative Example 7 like Figure 1 A self-fire extinguishing cable is shown, comprising: 3 wire cores; the 3 wire cores are distributed in a triangle shape, and a space is left in the middle when the 3 wire cores are closed, and the space is filled with nitrogen; each wire core includes a twisted conductor and an insulating layer; An anti-wear outer sheath is coated on the outside of the three wire cores; the anti-wear outer sheath is extruded from halogen-free, low-smoke, flame-retardant polyolefin insulation material; the fire extinguishing cotton prepared in Comparative Example 4 is filled between the three wire cores and the anti-wear outer sheath.

[0054] The self-extinguishing cable is made by the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 mm, the extrusion temperature is 150°C, and the screw speed is controlled at 20 r / min; obtaining the wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outside of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 180°C, and the strip is made into a cable wrapping tape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: The wear-resistant outer sheath is extruded on the outer side of the fire-extinguishing inner sheath at an extrusion temperature of 180°C and a screw speed of 10 r / min to obtain a self-extinguishing cable.

[0055] Comparative Example 8 like Figure 1 A self-fire extinguishing cable is shown, comprising: 3 wire cores; the 3 wire cores are distributed in a triangle shape, and a space is left in the middle when the 3 wire cores are closed, and the space is filled with nitrogen; each wire core includes a twisted conductor and an insulating layer; An anti-wear outer sheath is coated on the outside of the three wire cores; the anti-wear outer sheath is extruded from halogen-free, low-smoke, flame-retardant polyolefin insulation material; the fire extinguishing cotton prepared in Comparative Example 5 is filled between the three wire cores and the anti-wear outer sheath.

[0056] The self-extinguishing cable is made by the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 mm, the extrusion temperature is 150°C, and the screw speed is controlled at 20 r / min; obtaining the wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outside of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 180°C, and the strip is made into a cable wrapping tape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: The wear-resistant outer sheath is extruded on the outer side of the fire-extinguishing inner sheath at an extrusion temperature of 180°C and a screw speed of 10 r / min to obtain a self-extinguishing cable.

[0057] Example 10 like Figure 1 A self-fire extinguishing cable is shown, comprising: 3 wire cores; the 3 wire cores are distributed in a triangle shape, and a space is left in the middle when the 3 wire cores are closed, and the space is filled with nitrogen; each wire core includes a twisted conductor and an insulating layer; An anti-wear outer sheath is coated on the outside of the three wire cores; the anti-wear outer sheath is extruded from halogen-free, low-smoke, flame-retardant polyolefin insulation material; the fire extinguishing cotton prepared in Example 8 is filled between the three wire cores and the anti-wear outer sheath.

[0058] The self-extinguishing cable is made by the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 mm, the extrusion temperature is 150°C, and the screw speed is controlled at 20 r / min; obtaining the wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outside of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 180°C, and the strip is made into a cable wrapping tape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: The wear-resistant outer sheath is extruded on the outer side of the fire-extinguishing inner sheath at an extrusion temperature of 180°C and a screw speed of 10 r / min to obtain a self-extinguishing cable.

[0059] Embodiment 11 A self-extinguishing fire cable comprises: 4 wire cores; each wire core comprises a twisted conductor and an insulating layer; An anti-wear outer sheath is coated on the outside of the four wire cores; the anti-wear outer sheath is extruded from a halogen-free, low-smoke, flame-retardant polyolefin insulation material; the fire extinguishing cotton prepared in Example 8 is filled between the four wire cores and the anti-wear outer sheath.

[0060] The self-extinguishing cable is made by the following steps: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 2.8 mm, the extrusion temperature is 180°C, and the screw speed is controlled at 30 r / min; obtaining the wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outer side of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 150°C and the strip is made into a fire extinguishing inner protective layer. (4) Preparation of wear-resistant outer sheath: an wear-resistant outer sheath is extruded on the outer side of the fire-extinguishing inner sheath at a temperature of 150°C and a screw speed of 20 r / min to obtain a self-extinguishing cable.

[0061] Example 12 The self-extinguishing cables obtained in Examples 9 to 11 and Comparative Examples 6 to 8 were subjected to the following performance tests: Tensile strength and elongation at break: tested in accordance with GB / T 2951; Limiting oxygen index: tested according to ISO 4586; Stabilization time at 200°C: TG test: nitrogen atmosphere, heating rate of 10°C / min, room temperature to 650°C.

[0062] The results of the above performance tests are shown in Table 3.

[0063] Table 3 Performance test results of self-extinguishing cables It can be seen from the data of tensile strength and elongation at break that the self-extinguishing cable provided by the present invention has good toughness. It can be seen from the limiting oxygen index data that the self-extinguishing cable provided by the present invention has good flame retardant properties. It can be seen from the data of stabilization time at 200°C that the thermal stability of the self-extinguishing cables obtained in Examples 9 to 11 is better than that of the self-extinguishing cables obtained in Comparative Examples 6 to 8. This is because sufficient weight portions of carbonyl-modified carbon nanotubes are used in the self-extinguishing cables of Examples 9 to 11, and the carbon nanotubes have good compatibility with rubber in the fire extinguishing cotton, thereby enhancing the toughness, flame retardancy and thermal stability of the cable.

[0064] Comparing Example 9 with Comparative Example 6, the toughness, flame retardancy and thermal stability of the self-extinguishing cable of Comparative Example 6 are not good. The presumed reason is that in Comparative Example 1, the added carbon nanotubes are not modified. Therefore, in the fire extinguishing cotton of Comparative Example 3, there are fewer covalent bonds formed by grafting carbon nanotubes and EPDM rubber, which reduces the compatibility of the fire extinguishing agent and rubber in the fire extinguishing cotton. The toughness, flame retardancy and thermal stability of the self-extinguishing cable of Comparative Example 6 are also reduced accordingly.

[0065] Comparing Example 9 with Comparative Example 7, the toughness, flame retardancy and thermal stability of the self-extinguishing cable of Comparative Example 7 are not good. The presumed reason is that in Comparative Example 2, a small amount of carbonyl-modified carbon nanotubes are added. Therefore, in the fire-extinguishing cotton of Comparative Example 4, the covalent bonds formed by the grafting of carbon nanotubes and EPDM rubber are small, which reduces the compatibility of the fire extinguishing agent and rubber in the fire-extinguishing cotton. The toughness, flame retardancy and thermal stability of the self-extinguishing cable of Comparative Example 7 are also reduced accordingly.

[0066] Comparing Example 9 with Comparative Example 8, the toughness, flame retardancy and thermal stability of the self-extinguishing cable of Comparative Example 8 are not good. It is speculated that the reason is that the stirring temperature after the dry powder fire extinguishing agent is added to the EPDM rubber in Comparative Example 5 is too high, resulting in a side reaction. The grafting reaction of the EPDM rubber and the carbon nanotubes will produce by-products and generate impurities. Based on this, the present invention controls the temperature of the heating reaction at 80-100°C, which can accelerate the rate of the grafting reaction.

[0067] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A self-fire extinguishing cable, characterized in that: include: A plurality of wire cores and an anti-wear outer sheath covering the plurality of wire cores; fire extinguishing cotton is filled between the plurality of wire cores and the anti-wear outer sheath; The raw materials of the fire extinguishing cotton include the following components in parts by weight: 50-70 parts of dry powder fire extinguishing agent and 80-100 parts of EPDM rubber.

2. A self-fire extinguishing cable according to claim 1, characterized in that: The preparation method of the fire extinguishing cotton comprises the following steps: (S1) adding 10 to 15 parts of dry powder fire extinguishing agent to 80 to 100 parts of EPDM rubber, stirring at a low speed for 3 to 5 minutes at 80 to 100° C. to make the mixture uniform, cooling to room temperature and adding to an open mill, controlling the temperature at 150 to 180° C. to foam and granulate to obtain EPDM rubber sponge; (S2) adding 30 to 55 parts of dry powder fire extinguishing agent to the EPDM rubber sponge obtained in (S1), stirring at a low speed for 3 to 5 minutes at 80 to 100° C. to make the mixture uniform, and cooling to room temperature to obtain a finished product.

3. A self-fire extinguishing cable according to claim 1, characterized in that: The preparation method of the dry powder fire extinguishing agent comprises the following steps: According to the weight of the constituent raw materials, 100-120 parts of fire extinguishing base material, 5-10 parts of lubricant, and 3-5 parts of moisture-proof agent are weighed; grind and add 30-40 parts of fluorocarbon alkylamine, heat to 80-90° C., keep warm and stir, and vacuum dry; then add 15-30 parts of carbon nanotubes for high-speed ball milling, pass through a 400-500 mesh sieve, and obtain a dry powder fire extinguishing agent.

4. A self-fire extinguishing cable according to claim 3, characterized in that: The carbon nanotubes are carbonyl-modified carbon nanotubes, and the preparation method comprises the following steps: Weigh the carbon nanotube raw material and put it into a high-temperature furnace, evacuate the high-temperature furnace to less than or equal to -0.09MPa, introduce inert gas into the high-temperature furnace until the pressure in the high-temperature furnace is greater than the standard atmospheric pressure and the purity of the inert gas in the high-temperature furnace is greater than or equal to 98%, open the gas outlet of the high-temperature furnace to keep the inert gas flowing; heat the high-temperature furnace to 800-1000°C; stop inputting the inert gas, and input oxygen into the high-temperature furnace, the flow rate of the oxygen is 500-600mL / min; keep the high-temperature furnace warm until carbonyl-modified carbon nanotubes are formed.

5. A self-fire extinguishing cable according to claim 1, characterized in that: The fire extinguishing base material is one or more of sodium bicarbonate, sodium carbonate, ammonium carbonate and ammonium phosphate; The lubricant is one or more of magnesium stearate, mica powder and talc; The moisture-proof agent is silica gel.

6. A self-fire extinguishing cable according to claim 1, characterized in that: The number of the wire cores is 3, and the 3 wire cores are distributed in a triangle shape. When the 3 wire cores are closed, a space is left in the middle, and the space is filled with nitrogen.

7. A self-fire extinguishing cable according to claim 1, characterized in that: Each wire core includes a twisted conductor and an insulation layer.

8. A self-fire extinguishing cable according to claim 1, characterized in that: The wear-resistant outer protective layer is formed by extruding halogen-free, low-smoke, flame-retardant polyolefin insulating material.

9. A self-fire extinguishing cable according to claim 1, characterized in that: A fire-extinguishing inner protective layer is also provided on the inner side of the wear-resistant outer protective layer. The preparation method of the fire-extinguishing inner protective layer is to make the fire-extinguishing cotton into a strip shape to form a cable wrapping tape.

10. A method for preparing a self-fire extinguishing cable according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Conductor preparation; (2) Preparation of insulation layer: adopting a single-layer insulation production method, the thickness of the insulation layer is controlled between 0.70 and 2.8 mm, the extrusion temperature is 150 to 180°C, and the screw speed is controlled at 20 to 30 r / min; obtaining a wire core; (3) Preparation of fire extinguishing cotton: tightly wrap the insulation layer around the outer side of the wire core and squeeze in the fire extinguishing cotton. The extrusion temperature is 150-180°C and made into a strip shape to form a fire extinguishing inner protective layer; (4) Preparation of wear-resistant outer sheath: Extruding the wear-resistant outer sheath on the outer side of the fire-extinguishing inner sheath, the extrusion temperature is 150-180°C, and the screw speed is controlled at 10-20r / min to obtain a self-extinguishing cable.

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