Fireproof flame-retardant cable

Abstract

The invention discloses a fireproof flame-retardant cable, and relates to the field of power transmission and distribution line equipment. The preparation method comprises the following steps: performing ultrasonic radiation on organic bentonite to strip an interlayer structure, and then inserting rubber and acrylic acid into the interlayer structure of the bentonite in sequence to form a loose three-dimensional network structure. After mixing and adding phenyl phosphorus dichloride, cooking to generate an organic phosphorus flame-retardant compound and polymerizing. And then heating and drying bentonite to reduce the interplanar spacing, so that silicon oxide is generated, the structure is compact, the air contact surface is reduced, and the flame-retardant and fireproof effects are achieved. In addition, the composite bentonite and the alumina trihydrate are mixed as a filler to prepare the flame-retardant fireproof aerogel layer, the alumina trihydrate absorbs heat and is dehydrated when encountering high temperature, the temperature rise rate is slowed down, water is released to swell, the composite bentonite wraps, extends and is carbonized to prevent the combustible part from being in contact with combustion-supporting gas, and the flame-retardant effect is achieved. The cable prepared by the invention has fireproof and flame-retardant effects.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission and distribution line equipment, and particularly to a fireproof and flame-retardant cable. Background Art

[0002] Current flame-retardant wires and cables only have the function of high-temperature flame retardancy and cannot prevent fire. Generally, mica tapes are wound outside the conductor or insulating layer. When such a cable is in a high-temperature environment, although the mica tape is not affected by high temperature, the conductive conductor inside the mica tape is melted due to high temperature, resulting in the interruption of the line, and the insulating layer will also melt and even catch fire; in addition, the mica tape is easily dragged during the erection process of the wire and cable, resulting in mechanical damage, so that it cannot play the role of fire prevention and insulation.

[0003] Existing fireproof cables are either complex in structure, high in cost, or complex in manufacturing process, and have extremely high requirements for installation and laying, and their fireproof performance is not ideal. How to simplify the process and improve the fireproof performance of the cable while reducing material and production costs is of great significance. Organic bentonite has many excellent properties, such as good thermal stability, high residual carbon content, large reserves, low production cost, etc. However, due to its own structure, bentonite has a small interlayer spacing and is easy to agglomerate in the polymer matrix. In addition, the flame-retardant effect of bentonite is general and cannot meet the requirements of fireproof materials. However, there are a large number of exchangeable cations between the bentonite layers, which provides the necessary conditions for modification. Mixing the modified organic bentonite with aluminum trihydroxide to prepare an aerogel layer as a fireproof and flame-retardant layer, based on this idea, the present invention provides a fireproof and flame-retardant cable and its preparation method. Summary of the Invention

[0004] The purpose of the present invention is to provide a fireproof and flame-retardant cable and its preparation method to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: A fireproof and flame-retardant cable, from the inside to the outside, the cable sequentially includes an insulating cable core, a modified aerogel layer, a stainless steel layer, and an outer sheath layer.

[0006] Further, the modified aerogel layer is prepared by mixing organic composite bentonite and aluminum trihydroxide.

[0007] Further, the organic composite bentonite is obtained by subjecting bentonite to ultrasonic treatment, reacting with rubber and acrylic acid to generate an organic phosphorus-based flame retardant and polyacrylic acid, and then accumulating by heating.

[0008] Further, a preparation method of a fireproof and flame-retardant cable includes the following preparation steps: (1) Mix the organo - quaternary - ammonium - salt - intercalated bentonite with deionized water at a mass ratio of 1:1000 - 5000, oscillate it under ultrasonic waves with a frequency of 20 kHz - 120 kHz and a power of 100 W - 1200 W for 10 - 20 min, take the solid, and dry it at 50 °C for 2 h; heat the high - speed mixer to 180 - 200 °C, keep it at a constant temperature for 5 - 15 min, put in 6 - 10 parts of the dried bentonite and 2 parts of butyl rubber, stir at a speed of 600 r / min for 15 - 25 min, continue to stir and cool down to 110 - 120 °C, put in 1 - 5 parts of acrylic acid and continue to stir for 5 - 15 min, then put in 0.05 - 0.25 parts of phenyl dichlorophosphine and 0.08 - 0.2 parts of ammonium persulfate, continue to stir for 20 min, then carry out steam cooking, the cooking temperature is 80 - 100 °C, the cooking time is 4 - 6 h, after the cooking is completed, put it into a glass cup, place it in the heating chamber of a muffle furnace, the heating temperature is 105 °C, and the heating time is 1 - 15 d; after heating, cool it to room temperature to prepare the organic composite bentonite; (2) Soak polystyrene with a cross - linking degree of 5 - 15% in absolute ethanol for 24 - 48 h, take it out and air - dry it naturally at room temperature for 6 h. Put the air - dried polystyrene and tetrabutyl titanate into a mixed solution of dichloromethane and carbon tetrachloride, heat it to 50 °C, and stir at a speed of 200 - 300 r / min for 12 - 15 h, then lower the temperature to room temperature to obtain the aerogel precursor; (3) Use an extruder to extrude and wrap the aerogel precursor on the insulated cable core, the extrusion temperature is 55 - 65 °C, then place it in a high - pressure closed device, pressurize it to 16 MPa and heat it to 40 - 60 °C, and keep the temperature for 8 - 10 h. After completion, reduce the pressure and temperature to normal pressure and normal temperature to obtain a polystyrene aerogel layer cable; uniformly mix aluminum trihydrate, organic composite bentonite, polydopamine, vinyltriethoxysilane, and benzyl alcohol, then add 5 mm agate balls as ball - milling media, the ball - to - material ratio is 10:1, put the ball - milling tank on the ball - mill and ball - mill it at a rotation speed of 550 r / min for 15 - 75 min to obtain the filler; uniformly spray the filler on the surface of the polystyrene aerogel layer cable, then place it in a closed environment at 30 - 40 °C for 3 - 5 h, then raise the temperature to 70 - 80 °C and keep it for 2 - 3 h, and finally raise the temperature to 100 - 120 °C and keep it for 30 - 60 min to obtain the modified aerogel layer cable; (4) Use a stainless - steel strip to carry out on - line coating and welding on the cable core wrapped with the modified aerogel. The welded stainless - steel pipe is subjected to grooving treatment; wrap a sheath layer outside the stainless - steel layer, and its raw materials include the following components in parts by weight: 40 - 50 parts of chlorosulfonated polyethylene, 15 - 25 parts of chlorinated polyethylene, 8 - 16 parts of EVA, 20 - 30 parts of halogen - free low - smoke flame - retardant polyolefin, 1 - 2 parts of vinyltriethoxysilane, and 1 - 2 parts of silane coupling agent KH550.

[0009] Further, the size of the organic bentonite in step (1) is 20 - 200 mesh.

[0010] Further, in step (2), the weight ratio of air-dried low cross-linked polystyrene, tetrabutyl titanate, dichloromethane, and carbon tetrachloride is 10 - 16:1:20:50.

[0011] Further, in step (3), the mass parts of aluminum trihydrate, organic composite bentonite, polydopamine, vinyltriethoxysilane, and benzyl alcohol are 10 - 20 parts, 5 - 13 parts, 5 - 11 parts, 2 - 4 parts, and 15 - 35 parts respectively.

[0012] Further, in step (3), the weight ratio of the filler to the polystyrene aerogel is 0.5 - 1:1.

[0013] Further, in step (4), the silane coupling agent is silane coupling agent KH550.

[0014] Further, the stainless-steel sheath in step (4) is made by welding and grooving a stainless-steel strip with a thickness of 0.1 - 0.2 mm, a tensile strength of 520 - 595 MPa, and an elongation rate of 42% - 48%; during welding, a mixed gas of helium and argon with a volume ratio of 1:2 is used for protection; the minimum bending radius of the cable thus produced is 7 - 15 times the diameter of the cable.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention prepares an aerogel layer by mixing organic composite bentonite and inorganic aluminum trihydrate to wrap the cable, so as to achieve the effects of fire prevention and flame retardancy.

[0016] First, the organic bentonite is subjected to ultrasonic radiation to generate an interlayer exfoliated structure under the action of high-frequency mechanical waves. Then, rubber is inserted into the interlayer structure of the bentonite to form a composite material with a nano-dispersed structure. Acrylic acid is inserted into the gaps of the composite material, so that the composite material is infiltrated by acrylic acid to form a loose three-dimensional network structure. After adding phenyl dichlorophosphate and mixing, the bentonite is steamed with high-temperature water vapor. During the steaming process, part of the acrylic acid reacts with phenyl dichlorophosphate to generate an organophosphorus-based flame retardant compound, and the excess acrylic acid monomer is in-situ addition polymerized to obtain polyacrylic acid, which locks the organophosphorus-based flame retardant compound and makes it firmly adhere to the three-dimensional structure of the bentonite, capturing the free radicals generated by the pyrolysis of silicone rubber during combustion, so that the combustion reaction is inhibited and delayed. Then, while drying the bentonite by heating, the crystal plane spacing of the bentonite is reduced, and silicon oxides are generated by itself, cementing the remaining mineral components, so that the bentonite undergoes a condensation and accumulation behavior, and the structure of the composite bentonite tends to be compact, reducing the air contact surface to achieve the effect of flame retardancy and fire prevention. Secondly, the processed composite bentonite is mixed with aluminum trihydrate to prepare a flame-retardant and fireproof aerogel layer as a filler. When the temperature of the aerogel layer is too high, the aluminum trihydrate will absorb heat and dehydrate, slowing down the rate of temperature rise of the aerogel layer to achieve the flame-retardant effect. In addition, the released water will be absorbed by the surrounding composite bentonite. The swollen bentonite will wrap and extend due to the volume change, and carbonize to block the contact between the combustible part and the combustion-supporting gas, further achieving the flame-retardant effect through the synergistic mechanism with aluminum trihydrate. Detailed implementation mode

[0017] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] In order to more clearly illustrate the method provided by the present invention, the following examples are used for detailed description. The test methods for each index of a fireproof and flame-retardant cable manufactured in the following examples are as follows: Flame retardancy: The sample cables of the examples and the comparative examples are subjected to a flame-retardant test: The sample cables are kept vertical, the height of the torch flame for the test is 125 mm, the thermal power is 500 W, and they are burned for 15 s, then stopped for 15 s, and repeated 5 times. Then, observe the burning time of the remaining flame and determine the degree of burn according to the overall appearance after the flame goes out. The above experiment is carried out three times for each cable, and the average value is taken.

[0019] Oxygen index: The sample cables of the examples and the comparative examples are tested according to the method in GB / T2406-2008 "Test Method for Flammability of Plastics - Oxygen Index Method"; the corresponding standard value is ≥32 according to the standard in JB / T10707-2007; Example 1 (1) Mix bentonite intercalated with organic quaternary ammonium salt of 20 mesh with deionized water at a mass ratio of 1:1000, oscillate under ultrasonic waves with a frequency of 20 kHz and a power of 100 W for 10 min, take the solid, and dry it at 50 °C for 2 h; Heat the high-speed mixer to 180 °C, keep it at a constant temperature for 5 min, put in 6 parts of dried bentonite and 2 parts of butyl rubber, stir at a speed of 600 r / min for 15 min, continue to stir and cool down to 110 °C, put in 1 part of acrylic acid and continue to stir for 5 min, then put in 0.05 part of phenyl dichloride and 0.08 part of ammonium persulfate, continue to stir for 20 min, and then carry out steam cooking. The cooking temperature is 80 °C and the cooking time is 4 h. After the cooking is completed, put it into a glass cup and place it in the heating chamber of a muffle furnace. The heating temperature is 105 °C and the heating time is 1 d; After heating, cool it to room temperature to prepare organic composite bentonite; (2) Soak polystyrene with a crosslinking degree of 5% in absolute ethanol for 24 h, take it out and air-dry it naturally at room temperature for 6 h. Place the air-dried polystyrene and tetrabutyl titanate in a mixed solution of dichloromethane and carbon tetrachloride. The weight ratio of the air-dried low-crosslinking-degree polystyrene, tetrabutyl titanate, dichloromethane, and carbon tetrachloride is 10:1:20:50. Heat the mixed solution to 50 °C and stir it at a speed of 200 r / min for 12 h, then lower the temperature to room temperature to obtain the aerogel precursor; (3) Use an extruder to extrude and wrap the aerogel precursor on the insulated cable core. The extrusion temperature is 55 °C, and then place it in a high-pressure closed device, pressurize it to 16 MPa and raise the temperature to 40 °C, and maintain the temperature for 8 h. After completion, reduce the pressure and temperature to normal pressure and normal temperature to obtain a polystyrene aerogel layer cable; Mix 10 parts, 5 parts, 5 parts, 2 parts, and 15 parts by mass of aluminum trihydrate, organic composite bentonite, polydopamine, vinyltriethoxysilane, and benzyl alcohol respectively, and then add 5 mm agate balls as ball-milling media. The ball-to-material ratio is 10:1. Place the ball-milling tank on the ball mill and ball-mill it at a rotation speed of 550 r / min for 15 min respectively to obtain the filler; Spray the filler evenly on the surface of the polystyrene aerogel layer cable, and then place it in a closed environment at 30 °C for 3 h, then raise the temperature to 70 °C and keep it for 2 h, and finally raise the temperature to 100 °C and keep it for 30 min to obtain the modified aerogel layer cable; (4) Use a stainless steel strip to conduct on-line coating and welding on the cable core wrapped with the modified aerogel. The welded stainless steel pipe is subjected to grooving treatment; The stainless steel sheath is made by welding and grooving a stainless steel strip with a thickness of 0.1 mm, a tensile strength of 520 MPa, and an elongation rate of 42%. During welding, a mixed gas of helium and argon with a volume ratio of 1:2 is used for protection; The minimum bending radius of the obtained cable is 7 times the diameter of the cable; Wrap a sheath layer outside the stainless steel layer, and its raw materials include the following components in parts by weight: 40 parts of chlorosulfonated polyethylene, 15 parts of chlorinated polyethylene, 8 parts of EVA, 20 parts of halogen-free low-smoke flame-retardant polyolefin, 1 part of vinyltriethoxysilane, and 1 part of silane coupling agent KH550.

[0020] Example 2 (1) Mix the 110-mesh organic quaternary ammonium salt intercalated bentonite with deionized water at a mass ratio of 1:3000, oscillate it for 15 min under ultrasonic waves with a frequency of 70 kHz and a power of 650 W, take the solid, and dry it at 50 °C for 2 h; heat the high-speed mixer to 190 °C, keep it at a constant temperature for 10 min, put in 8 parts of the dried bentonite and 2 parts of butyl rubber, stir at a speed of 600 r / min for 20 min, continue to stir and cool down to 115 °C, put in 3 parts of acrylic acid and continue to stir for 10 min, then put in 0.15 parts of phenyl dichlorophosphine and 0.14 parts of ammonium persulfate, continue to stir for 20 min, and then carry out steam cooking. The cooking temperature is 90 °C and the cooking time is 5 h. After cooking, put it into a glass cup and place it in the heating chamber of a muffle furnace. The heating temperature is 105 °C and the heating time is 8 d; after heating, cool it to room temperature to prepare the organic composite bentonite. (2) Soak the polystyrene with a crosslinking degree of 10% in absolute ethanol for 36 h, take it out and air-dry it naturally at room temperature for 6 h. Put the air-dried polystyrene and tetrabutyl titanate into a mixed solution of dichloromethane and carbon tetrachloride. The weight ratio of the air-dried low-crosslinking polystyrene, tetrabutyl titanate, dichloromethane, and carbon tetrachloride is 13:1:20:50; heat the mixed solution to 50 °C, stir at a speed of 250 r / min for 13.5 h, and then cool it down to room temperature to obtain the aerogel precursor. (3) Use an extruder to extrude and wrap the aerogel precursor on the insulated cable core. The extrusion temperature is 60 °C, and then place it in a high-pressure closed device, pressurize it to 16 MPa and heat it to 50 °C, and keep the temperature for 9 h. After completion, reduce the pressure and cool it down to normal pressure and normal temperature to obtain the polystyrene aerogel layer cable; mix 15 parts, 9 parts, 8 parts, 3 parts, and 25 parts of aluminum trihydrate, organic composite bentonite, polydopamine, vinyltriethoxysilane, and benzyl alcohol by mass, and then add 5 mm agate balls as the ball-milling medium. The ball-to-material ratio is 10:1. Put the ball-milling tank on the ball mill and ball-mill it at a speed of 550 r / min for 45 min respectively to obtain the filler; evenly spray the filler on the surface of the polystyrene aerogel layer cable, then place it in a closed environment at 35 °C and keep it for 4 h, then heat it to 75 °C and keep it for 2.5 h, and finally heat it to 110 °C and keep it for 45 min to obtain the modified aerogel layer cable. (4) The cable core wrapped with modified aerogel is coated and welded online with a stainless steel strip. After welding, the stainless steel pipe is subjected to grooving treatment. The stainless steel sheath is made by welding and grooving a stainless steel strip with a thickness of 0.15 mm, a tensile strength of 560 MPa, and an elongation rate of 45%. During welding, a mixed gas of helium and argon with a volume ratio of 1:2 is used for protection. The minimum bending radius of the manufactured cable is 11 times the diameter of the cable. A sheath layer is wrapped outside the stainless steel layer, and its raw materials include the following components in parts by weight: 45 parts of chlorosulfonated polyethylene, 20 parts of chlorinated polyethylene, 12 parts of EVA, 25 parts of halogen-free low-smoke flame-retardant polyolefin, 1.5 parts of vinyltriethoxysilane, and 1.5 parts of silane coupling agent KH550.

[0021] Example 3 (1) The 200-mesh organo-quaternary ammonium salt intercalated bentonite and deionized water are mixed at a mass ratio of 1:5000, oscillated for 20 min under ultrasonic waves with a frequency of 120 kHz and a power of 1200 W, and the solid is taken and dried at 50°C for 2 h. The high-speed mixer is heated to 200°C and kept at a constant temperature for 15 min. 10 parts of dried bentonite and 2 parts of butyl rubber are put in and stirred at a speed of 600 r / min for 25 min. Stirring is continued and the temperature is lowered to 120°C, then 5 parts of acrylic acid are put in and stirred for 15 min. Subsequently, 0.25 parts of phenyl dichlorophosphine and 0.2 parts of ammonium persulfate are put in and stirred for 20 min. Then, steam cooking is carried out, the cooking temperature is 100°C, and the cooking time is 6 h. After cooking is completed, it is filled into a glass cup and placed in the heating chamber of a muffle furnace. The heating temperature is 105°C and the heating time is 15 d. After heating, it is cooled to room temperature to prepare the organic composite bentonite. (2) The polystyrene with a crosslinking degree of 15% is soaked in absolute ethanol for 48 h, taken out and naturally air-dried at room temperature for 6 h. The air-dried polystyrene and tetrabutyl titanate are placed in a mixed solution of dichloromethane and carbon tetrachloride. The weight ratio of the air-dried low-crosslinking-degree polystyrene, tetrabutyl titanate, dichloromethane, and carbon tetrachloride is 16:1:20:50. The mixed solution is heated to 50°C and stirred at a speed of 300 r / min for 15 h, and then the temperature is lowered to room temperature to obtain the aerogel precursor. (3) Use an extruder to extrude and wrap the aerogel precursor around the insulated cable core at an extrusion temperature of 65 °C, then place it in a high-pressure closed equipment, pressurize it to 16 MPa and heat it to 60 °C, and maintain the temperature for 10 h. After completion, reduce the pressure and cool it down to normal pressure and normal temperature to obtain a polystyrene aerogel layer cable; Mix aluminum trihydrate, organic composite bentonite, polydopamine, vinyltriethoxysilane, and benzyl alcohol according to 20 parts, 13 parts, 11 parts, 4 parts, and 35 parts by mass, then add 5 mm agate balls as ball milling media, with a ball-to-material ratio of 10:1. Place the ball milling tank on the ball mill and ball mill at a speed of 550 r / min for 75 min respectively to obtain a filler; Spray the filler evenly on the surface of the polystyrene aerogel layer cable, then place it in a closed environment at 40 °C for 5 h, then heat it to 80 °C and maintain it for 3 h, and finally heat it to 120 °C and maintain it for 60 min to obtain a modified aerogel layer cable; (4) Use a stainless steel strip to conduct on-line coating and welding on the cable core wrapped with the modified aerogel. After welding, the stainless steel pipe is subjected to grooving treatment; The stainless steel sheath is made by welding and grooving a stainless steel strip with a thickness of 0.2 mm, a tensile strength of 595 MPa, and an elongation rate of 48%; During welding, a mixed gas of helium and argon with a volume ratio of 1:2 is used for protection; The minimum bending radius of the cable obtained is 15 times the diameter of the cable; Wrap a sheath layer outside the stainless steel layer, and its raw materials include the following components in parts by weight: 50 parts of chlorosulfonated polyethylene, 25 parts of chlorinated polyethylene, 16 parts of EVA, 30 parts of halogen-free low-smoke flame-retardant polyolefin, 2 parts of vinyltriethoxysilane, and 2 parts of silane coupling agent KH550.

[0022] Comparative Example 1 The difference between Comparative Example 1 and Example 2 lies in the difference in step (1). Modify step (1) as follows: Mix 110-mesh organo-quaternary ammonium salt intercalated bentonite and deionized water at a mass ratio of 1:3000, oscillate it under ultrasonic waves with a frequency of 70 kHz and a power of 650 W for 15 min, take the solid, and dry it at 50 °C for 2 h; Heat the high-speed mixer to 190 °C, keep it at a constant temperature for 10 min, put in 8 parts of dried bentonite and 3 parts of acrylic acid, stir at a speed of 600 r / min for 20 min, continue to stir and cool down to 115 °C, then put in 0.15 parts of phenyl dichlorophosphine and 0.14 parts of ammonium persulfate, continue to stir for 20 min, and then carry out steam cooking. The cooking temperature is 90 °C and the cooking time is 5 h. After the cooking is completed, put it into a glass cup and place it in the heating chamber of a muffle furnace. The heating temperature is 105 °C and the heating time is 8 d; After heating, cool it to room temperature to prepare organic composite bentonite; The remaining steps are the same as those in Example 2.

[0023] Comparative Example 2 The difference between Comparative Example 2 and Example 2 lies in step (1). Step (1) is changed to: Mix bentonite intercalated with organic quaternary ammonium salt of 110 mesh with deionized water at a mass ratio of 1:3000, oscillate for 15 min under ultrasonic waves with a frequency of 70 kHz and a power of 650 W, take the solid, and dry it at 50°C for 2 h; Heat the high-speed mixer to 190°C, keep it at a constant temperature for 10 min, add 8 parts of dried bentonite and 2 parts of butyl rubber, stir at a speed of 600 r / min for 20 min, continue stirring and cool down to 115°C, add 3 parts of acrylic acid and continue stirring for 10 min, then add 0.15 part of phenyl dichlorophosphine and continue stirring for 20 min, then carry out steam cooking, the cooking temperature is 90°C, and the cooking time is 5 h. After the cooking is completed, put it into a glass cup and place it in the heating chamber of a muffle furnace, the heating temperature is 105°C, and the heating time is 8 d; After heating, cool it to room temperature to prepare organic composite bentonite; The remaining steps are the same as those in Example 2.

[0024] Comparative Example 3 The difference between Comparative Example 3 and Example 2 lies in step (1). Step (1) is changed to: Mix bentonite intercalated with organic quaternary ammonium salt of 110 mesh with deionized water at a mass ratio of 1:3000, oscillate for 15 min under ultrasonic waves with a frequency of 70 kHz and a power of 650 W, take the solid, and dry it at 50°C for 2 h; Heat the high-speed mixer to 190°C, keep it at a constant temperature for 10 min, add 8 parts of dried bentonite and 2 parts of butyl rubber, stir at a speed of 600 r / min for 20 min, continue stirring and cool down to 115°C, add 3 parts of acrylic acid and continue stirring for 10 min, then add 0.14 part of ammonium persulfate and continue stirring for 20 min, then carry out steam cooking, the cooking temperature is 90°C, and the cooking time is 5 h. After the cooking is completed, put it into a glass cup and place it in the heating chamber of a muffle furnace, the heating temperature is 105°C, and the heating time is 8 d; After heating, cool it to room temperature to prepare organic composite bentonite; The remaining steps are the same as those in Example 2.

[0025] Comparative Example 4 The difference between Comparative Example 4 and Example 2 lies in step (1). Step (1) is changed to: Mix bentonite intercalated with organic quaternary ammonium salt of 110 mesh with deionized water at a mass ratio of 1:3000, oscillate for 15 min under ultrasonic waves with a frequency of 70 kHz and a power of 650 W, take the solid, and dry it at 50°C for 2 h; Heat the high-speed mixer to 190°C, keep it at a constant temperature for 10 min, put in 8 parts of dried bentonite and 2 parts of butyl rubber, stir at a speed of 600 r / min for 20 min, continue to stir and cool down to 115°C, put in 3 parts of acrylic acid and continue to stir for 10 min, then put in 0.15 parts of phenyl dichlorophosphine and 0.14 parts of ammonium persulfate, continue to stir for 20 min, then carry out steam cooking, the cooking temperature is 90°C, the cooking time is 5 h, after the cooking is completed, put it into a constant temperature drying oven, dry it at 50°C for 5 h to prepare organic composite bentonite; The remaining steps are the same as those in Example 2.

[0026] Comparative Example 5 The difference between Comparative Example 5 and Example 2 lies in step (3). Step (3) is changed to: Use an extruder to extrude and wrap the aerogel precursor on the insulated cable core, the extrusion temperature is 60°C, then place it in a high-pressure closed device, pressurize to 16 MPa and heat up to 50°C, and keep the temperature for 9 h. After completion, depressurize and cool down to normal pressure and normal temperature to obtain a polystyrene aerogel layer cable; Mix organic composite bentonite, polydopamine, vinyltriethoxysilane and benzyl alcohol in 15 parts, 9 parts, 8 parts, 3 parts and 25 parts by mass respectively, then add 5 mm agate balls as ball milling media, the ball-to-material ratio is 10:1, put the ball milling tank on the ball mill and ball mill at a rotation speed of 550 r / min for 45 min respectively to obtain a filler; Spray the filler evenly on the surface of the polystyrene aerogel layer cable, then place it in a closed environment at 35°C for 4 h, then heat up to 75°C and keep it for 2.5 h, and finally heat up to 110°C and keep it for 45 min to obtain a modified aerogel layer cable; The remaining steps are the same as those in Example 2.

[0027] Effect Example The following Table 1 gives the performance analysis results of a fireproof and flame-retardant cable using Examples 1 to 3 and Comparative Examples 1 to 5 of the present invention.

[0028] Table 1 From the comparison of the experimental data on the flame retardancy and oxygen index between the examples and the comparative examples, it can be found that in the present invention, organic bentonite is subjected to ultrasonic radiation to generate an interlayer exfoliated structure under the action of high-frequency mechanical waves. Then, rubber is inserted into the interlayer structure of bentonite to form a composite material with a nano-dispersed structure. Acrylic acid is interspersed in the gaps of the composite material, so that the composite material is infiltrated by acrylic acid to form a loose three-dimensional network structure. After adding phenyl dichlorophosphine and mixing, the bentonite is steamed with high-temperature water vapor. During the steaming process, part of the acrylic acid reacts with phenyl dichlorophosphine to generate an organophosphorus-based flame retardant compound, and the excess acrylic acid monomers are in-situ addition polymerized to obtain polyacrylic acid, which locks the organophosphorus-based flame retardant compound and makes it firmly adhere to the three-dimensional structure of bentonite, capturing the free radicals generated by the pyrolysis during the combustion of silicone rubber, so that the combustion reaction is inhibited and delayed. Then, while drying the bentonite by heating, the crystal plane spacing of the bentonite is reduced, and silicon oxides are generated by itself, cementing the remaining mineral components, so that the bentonite undergoes a condensation and accumulation behavior, and the structure of the composite bentonite tends to be compact, reducing the air contact surface to achieve the effect of flame retardancy and fire prevention. The present invention uses the treated composite bentonite mixed with aluminum trihydroxide as a filler to prepare a flame-retardant and fire-proof aerogel layer. When the temperature of the aerogel layer is too high, aluminum trihydroxide will absorb heat and dehydrate, slowing down the rate of temperature rise of the aerogel layer to achieve the flame retardant effect. In addition, the released water will be absorbed by the surrounding composite bentonite. The swollen bentonite wraps and extends due to the volume change, and carbonizes to block the contact between the combustible part and the combustion-supporting gas. The aerogel prepared in this way makes the cable have the effect of fire prevention and flame retardancy.

[0029] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claimed claim.

Claims

1. A fireproof and flame-retardant cable, which sequentially comprises an insulating cable core, a modified aerogel layer, a stainless steel layer, and an outer sheath layer from inside to outside, and is characterized in that, It includes the following preparation steps: (1) Mix bentonite intercalated with organic quaternary ammonium salt of 20 mesh with deionized water at a mass ratio of 1:1000, oscillate it under ultrasonic waves with a frequency of 20 kHz and a power of 100 W for 10 min, take the solid, and dry it at 50 °C for 2 h; heat the high-speed mixer to 180 °C, keep it at a constant temperature for 5 min, put 6 parts of bentonite and 2 parts of butyl rubber after drying into it, stir at a speed of 600 r / min for 15 min, continue to stir and cool down to 110 °C, put 1 part of acrylic acid into it and continue to stir for 5 min, then put 0.05 part of phenyl dichlorophosphine and 0.08 part of ammonium persulfate into it, continue to stir for 20 min, and then carry out steam cooking. The cooking temperature is 80 °C and the cooking time is 4 h. After the cooking is completed, put it into a glass cup and place it in the heating chamber of a muffle furnace. The heating temperature is 105 °C and the heating time is 1 d; after heating, cool it to room temperature to prepare organic composite bentonite; (2) Immerse polystyrene with a crosslinking degree of 5% in absolute ethanol for 24 h, take it out and air-dry it naturally at room temperature for 6 h. Put the air-dried polystyrene and tetrabutyl titanate into a mixed solution of dichloromethane and carbon tetrachloride. The weight ratio of air-dried low-crosslinking-degree polystyrene, tetrabutyl titanate, dichloromethane, and carbon tetrachloride is 10:1:20:50; heat the mixed solution to 50 °C and stir it at a speed of 200 r / min for 12 h, and then lower the temperature to room temperature to obtain an aerogel precursor; (3) Use an extruder to extrude and wrap the aerogel precursor on an insulating cable core. The extrusion temperature is 55 °C, and then place it in a high-pressure closed device, pressurize it to 16 MPa and heat it to 40 °C, and keep the temperature for 8 h. After completion, reduce the pressure and temperature to normal pressure and normal temperature to obtain a polystyrene aerogel layer cable; mix 10 parts, 5 parts, 5 parts, 2 parts, and 15 parts by mass of aluminum trihydrate, organic composite bentonite, polydopamine, vinyltriethoxysilane, and benzyl alcohol respectively, and then add 5 mm agate balls as ball-milling media. The ball-to-material ratio is 10:

1. Put the ball-milling tank on a ball mill and ball-mill it at a rotation speed of 550 r / min for 15 min respectively to obtain a filler; evenly spray the filler on the surface of the polystyrene aerogel layer cable, and then place it in a closed environment at 30 °C for 3 h, then heat it to 70 °C and keep it for 2 h, and finally heat it to 100 °C and keep it for 30 min to obtain a modified aerogel layer cable; (4) Use a stainless steel strip to conduct on-line cladding and welding on the cable core wrapped with the modified aerogel. The welded stainless steel pipe is subjected to grooving treatment; the stainless steel sheath is made by welding and grooving a stainless steel strip with a thickness of 0.1 mm, a tensile strength of 520 MPa, and an elongation rate of 42%; during welding, a mixed gas of helium and argon with a volume ratio of 1:2 is used for protection; the minimum bending radius of the obtained cable is 7 times the diameter of the cable; wrap a sheath layer outside the stainless steel layer, and its raw materials include the following components in parts by weight: 40 parts of chlorosulfonated polyethylene, 15 parts of chlorinated polyethylene, 8 parts of EVA, 20 parts of halogen-free low-smoke flame-retardant polyolefin, 1 part of vinyltriethoxysilane, and 1 part of silane coupling agent KH550.

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