Preparation method of composite explosion-proof control cable

Abstract

The application discloses a preparation method of a composite explosion-proof control cable and relates to the technical field of cables. The cable comprises, from inside to outside, a copper conductor, an insulation layer, a mica tape wrapped fire-resistant layer, nano-modified polyolefin sheath, a galvanized steel wire braided armored layer and a flame-retardant polyvinyl chloride outer sheath. Nano-zinc oxide powder is added to the insulation layer material, and the surface of the insulation layer is modified by passing sulfur vapor by adopting a co-extrusion and in-situ vulcanization process. Cross-linking reaction occurs between sulfur and the polymer of the surface layer of the insulation layer, and the nano-zinc oxide on the surface of the insulation layer is reacted, thereby generating a thin layer of zinc sulfide with high thermal stability in-situ, forming a dense physical covering layer, effectively preventing direct ablation of the insulation layer body by a high-temperature electric arc, and reducing the risk of breakdown of the insulation layer and explosion.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and specifically to a method for preparing a composite explosion-proof control cable. Background Technology

[0002] Currently, control cables used in flammable and explosive environments mostly use cross-linked polyethylene or similar polyolefin thermosetting resins as their insulation material. These materials exhibit good dielectric properties and thermal aging life under normal electrical conditions, but they reveal several inherent defects in the actual service conditions of explosion-proof cables.

[0003] First, when cross-linked polyethylene insulation is exposed to high-temperature electric arcs or direct external flames, the material surface rapidly undergoes pyrolysis, melting, or even combustion, causing a sharp drop in insulation resistance. This makes it highly susceptible to forming conductive paths and generating electric sparks between the conductor and the metal armor layer or shielding layer, becoming an ignition source in explosive gas or dust environments. To improve flame retardancy, existing technologies typically add halogenated flame retardants or large amounts of inorganic hydroxide fillers to the insulation material. However, these additives significantly degrade the mechanical flexibility and extrusion processability of the insulation layer, leading to cracks when cables are bent and laid inside equipment. Furthermore, halogenated flame retardants release large amounts of corrosive and toxic fumes during combustion, increasing the risk of secondary disasters. Second, conventional cross-linked polyethylene insulation lacks an inorganic protective coating. After long-term electrochemical aging, erosion in humid environments, or mechanical damage, microscopic pores and cracks easily form on the surface. These defects become inducing sites for partial discharge. The continued action of partial discharge further accelerates insulation degradation, gradually developing into penetrating breakdown, ultimately triggering a discharge spark and causing an explosion.

[0004] While existing technologies employ external mica tape wrapping or ceramicized polyolefin sheathing, these external layers are merely physically bonded to the insulation layer. Under bending and thermal cycling conditions during cable manufacturing and use, delamination or peeling can easily occur, resulting in insufficient reliability and durability of the protective effect. Furthermore, cross-linked polyethylene itself lacks a self-protective mechanism for endothermic decomposition at high temperatures. Once heat penetrates the surface, it rapidly transfers to deeper layers, causing the insulation layer to soften, deform, or even lose its mechanical integrity. Some researchers have attempted to incorporate micron-sized inorganic powders into the insulation layer to improve arc resistance, but powder agglomeration and compatibility issues with the matrix make uniform powder distribution difficult. Moreover, the presence of inorganic particles often becomes a new electric field concentration point, increasing the probability of partial discharge. Based on this background, there is a need to develop a method that can form an inorganic heat-resistant protective layer in situ on the surface of the insulation layer without sacrificing its flexibility and processability, thereby simultaneously improving its resistance to arc erosion, flame retardancy, and suppression of partial discharge. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a composite explosion-proof control cable to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a composite explosion-proof control cable, wherein the cable comprises, from the inside out, a copper conductor, an insulation layer, a mica tape wrapped fire-resistant layer, a nano-modified polyolefin sheath, a galvanized steel wire braided armor layer, and a flame-retardant polyvinyl chloride outer sheath. The insulating layer material is prepared by adding nano zinc oxide powder and modifying the surface of the insulating layer by introducing sulfur vapor through co-extrusion and in-situ vulcanization processes.

[0007] Furthermore, the insulating layer, by weight, comprises 100 parts of cross-linked polyethylene matrix resin, 6-10 parts of nano zinc oxide powder, 0.3-0.7 parts of antioxidant 1010, 0.2-0.5 parts of antioxidant 168, 0.5-1.0 parts of dicumyl peroxide, 0.2-0.5 parts of triallyl isocyanurate, and 0.15-0.3 parts of zinc stearate.

[0008] Furthermore, a method for preparing a composite explosion-proof control cable includes the following preparation steps: (1) Cross-linked polyethylene matrix resin, nano zinc oxide powder, antioxidant 1010, antioxidant 168, dicumyl peroxide, triallyl isocyanurate, and zinc stearate are put into a high-speed mixer and stirred at room temperature to make the nano zinc oxide and each additive uniformly dispersed; then the mixture is fed into a twin-screw extruder, melt-blended and granulated to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head, where the above-mentioned insulating granules are melted and extruded onto the surface of the conductor to form an insulating layer; (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel, which is maintained at atmospheric pressure to slightly positive pressure. Solid sulfur is heated in the evaporator, and nitrogen gas is bubbled through the evaporator to carry out saturated sulfur vapor. The mixed gas is heated by the preheater before entering the reaction channel. The insulated wire core stays in the channel for 60s-150s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank to allow the insulation layer to cool and solidify rapidly; (5) Double-layer mica tape is wrapped around the cooled insulated core to form a fire-resistant layer; then a nano-modified polyolefin sheath is extruded over the mica tape. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath, and after passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

[0009] Furthermore, in step (2), the extrusion thickness of the insulating layer is 1 mm.

[0010] Furthermore, in step (3), the reaction channel length is 1.5m-3m.

[0011] Furthermore, in step (3), the solid sulfur is placed in an evaporator and heated to 160°C-180°C.

[0012] Furthermore, in step (3), the flow rate of nitrogen is 1.0 L / min to 2.0 L / min.

[0013] Furthermore, in step (3), the preheater is heated to 160°C-180°C.

[0014] Furthermore, in step (4), the water temperature of the cooling water tank is controlled between 15℃ and 35℃.

[0015] Furthermore, in step (5), the thickness of the polyolefin sheath is 0.9mm-1.6mm.

[0016] Furthermore, the cross-linked polyethylene matrix resin, model LD100BW, is sourced from Sinopec Beijing Yanhua Petrochemical Co., Ltd., with a melt flow rate of 2.1 g / 10 min and a density of 0.922 g / cm³.

[0017] Furthermore, the nano zinc oxide powder, model VK-J30, is from Xuancheng Jingrui New Materials Co., Ltd., with an average particle size of 30nm; lead (Pb) content: 0-0.001%; ​​manganese (Mn) content: 0-0.001%; ​​copper (Cu) content: 0-0.002%.

[0018] Furthermore, the triallyl isocyanurate, model number TAIC, is from Shanghai Dunmei, with a bromine value of 183-188, an acid value of 2-0.2 mg KOH / g, and a density of 1.155 g / mL.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. This invention adds nano-zinc oxide powder to the insulating layer material, which is then uniformly dispersed in the cross-linked polyethylene matrix. When sulfur vapor is introduced onto the surface of the insulating layer using a co-extrusion and in-situ vulcanization process, the sulfur vapor not only undergoes a cross-linking reaction with the polymer on the surface of the insulating layer, but also reacts with the nano-zinc oxide on the surface of the insulating layer, generating a thin layer of zinc sulfide with high thermal stability in situ. This forms a dense physical covering layer, effectively preventing the direct ablation of the insulating layer by a high-temperature electric arc, thereby reducing the risk of the insulating layer being broken down and causing an explosion.

[0020] 2. The addition of nano zinc oxide enhances the reactivity of the insulation layer with sulfur vapor. The generated zinc sulfide grains make the surface of the insulation layer more compact, which increases the partial discharge initiation voltage and reduces the possibility of sparks or arcs caused by weak points in the insulation, thus improving the explosion-proof safety of the conductor.

[0021] 3. When exposed to external flames or high-temperature electric arcs, the zinc sulfide layer on the surface of the insulation layer undergoes endothermic decomposition. This decomposition process consumes a large amount of heat energy, inhibiting the rate of temperature rise of the insulation layer itself. The resulting zinc oxide remains in solid form on the surface of the insulation layer, continuing to function as an oxygen barrier. This synergistic effect gives the insulation layer excellent flame-retardant properties.

[0022] 4. The insulation layer of the present invention retains good mechanical flexibility after vulcanization treatment. Because the vulcanization reaction is limited to the surface area of ​​the insulation layer, its elongation at break and bending performance still meet the requirements of cable wiring inside equipment. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The testing methods for various indicators of a composite explosion-proof control cable manufactured in the following embodiments are as follows: Tensile strength and elongation at break: Cables of the same length from the example and comparative examples were tested in accordance with GB / T 2951.

[0025] 200℃ thermal stability time: Take cables of the same length as the example and the comparative example, raise the temperature of the thermal aging test chamber to about 200℃, and quickly put the cables into it. Start timing when the temperature reaches 200℃, and observe the color change. Record the time required for the color to start to turn slightly yellow as the thermal stability time at 200℃.

[0026] Flame retardancy: Cables of the same length from both the example and the comparative example were tested according to IEC 60332-3.

[0027] Oxygen Index: The oxygen index of the example and comparative cables of the same length is based on GB2406-2008 standard.

[0028] Example 1 (1) According to the following mass parts, cross-linked polyethylene matrix resin 100 parts, nano zinc oxide powder 6 parts, antioxidant 1010 0.3 parts, antioxidant 168 0.2 parts, dicumyl peroxide 0.5 parts, triallyl isocyanurate 0.2 parts, zinc stearate 0.15 parts; put the above raw materials into a high-speed mixer and stir at room temperature for 15 minutes to make the nano zinc oxide and each additive uniformly dispersed; then feed the mixture into a twin-screw extruder and melt blend and granulate at 130°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The extruder head temperature is controlled at 130°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel. The channel is 1.5m long and is kept at atmospheric pressure to slightly positive pressure. The absolute pressure is 0.10MPa. Solid sulfur is placed in the evaporator and heated to 160°C. Nitrogen gas is bubbled through the evaporator at a flow rate of 1.0L / min under standard conditions to carry out saturated sulfur vapor. The mixed gas is preheated to 160°C before entering the reaction channel to control the sulfur vapor volume fraction at 0.5%. The temperature in the reaction channel is maintained at 160°C and the insulated wire core stays in the channel for 60s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank. The water temperature is controlled at 15°C to allow the insulation layer to cool and solidify rapidly, thus terminating all chemical reactions. (5) Wrap mica tape in two layers with an overlap of 20% around the cooled insulated core to form a fire-resistant layer; then extrude a nano-modified polyolefin sheath over the mica tape. The polyolefin sheath has a thickness of 0.9 mm. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath with a thickness of 1.5mm. After passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

[0029] Example 2 (1) According to the following mass parts, cross-linked polyethylene matrix resin 100 parts, nano zinc oxide powder 7 parts, antioxidant 1010 0.4 parts, antioxidant 168 0.3 parts, dicumyl peroxide 0.6 parts, triallyl isocyanurate 0.3 parts, zinc stearate 0.2 parts; put the above raw materials into a high-speed mixer and stir at room temperature for 15 minutes to make the nano zinc oxide and each additive uniformly dispersed; then feed the mixture into a twin-screw extruder and melt blend and granulate at 135°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The extruder head temperature is controlled at 135°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel. The channel is 1.875m long and is kept at atmospheric pressure to slightly positive pressure with an absolute pressure of 0.10MPa. Solid sulfur is heated to 165°C in an evaporator. Nitrogen gas is bubbled through the evaporator at a flow rate of 1.25L / min under standard conditions to carry out saturated sulfur vapor. The mixed gas is heated to 165°C by a preheater before entering the reaction channel to control the sulfur vapor volume fraction at 0.6%. The temperature in the reaction channel is maintained at 165°C and the insulated wire core stays in the channel for 85s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank. The water temperature is controlled at 20°C to allow the insulation layer to cool and solidify rapidly, thus terminating all chemical reactions. (5) Wrap mica tape in two layers with an overlap of 25% around the cooled insulated core to form a fire-resistant layer; then extrude a nano-modified polyolefin sheath over the mica tape. The polyolefin sheath has a thickness of 1.1 mm. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath with a thickness of 1.5mm. After passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

[0030] Example 3 (1) According to the following mass parts, cross-linked polyethylene matrix resin 100 parts, nano zinc oxide powder 8 parts, antioxidant 1010 0.5 parts, antioxidant 168 0.35 parts, dicumyl peroxide 0.75 parts, triallyl isocyanurate 0.35 parts, zinc stearate 0.25 parts; put the above raw materials into a high-speed mixer and stir at room temperature for 20 minutes to make the nano zinc oxide and each additive uniformly dispersed; then feed the mixture into a twin-screw extruder and melt blend and granulate at 140°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The temperature of the extruder head is controlled at 140°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After leaving the extruder head, the insulated wire core immediately enters the closed reaction channel, which is 2.25m long and is kept at atmospheric pressure to slightly positive pressure, with an absolute pressure of 0.125MPa. Solid sulfur is heated to 170°C in an evaporator, and nitrogen gas is bubbled through the evaporator at a flow rate of 1.5L / min under standard conditions to carry out saturated sulfur vapor. The mixed gas is preheated to 170°C before entering the reaction channel to control the sulfur vapor volume fraction at 0.75%. The temperature in the reaction channel is maintained at 175°C, and the insulated wire core stays in the channel for 105s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank. The water temperature is controlled at 25°C to allow the insulation layer to cool and solidify rapidly, thus terminating all chemical reactions. (5) Wrap mica tape in two layers with an overlap of 25% around the cooled insulated core to form a fire-resistant layer; then extrude a nano-modified polyolefin sheath over the mica tape. The polyolefin sheath has a thickness of 1.25 mm. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath with a thickness of 1.5mm. After passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

[0031] Example 4 (1) According to the following mass parts, cross-linked polyethylene matrix resin 100 parts, nano zinc oxide powder 9 parts, antioxidant 1010 0.6 parts, antioxidant 168 0.45 parts, dicumyl peroxide 0.9 parts, triallyl isocyanurate 0.5 parts, zinc stearate 0.3 parts; put the above raw materials into a high-speed mixer and stir at room temperature for 25 minutes to make the nano zinc oxide and each additive uniformly dispersed; then feed the mixture into a twin-screw extruder and melt blend and granulate at 145°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The temperature of the extruder head is controlled at 145°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel. The channel is 3m long and is kept at normal pressure to slightly positive pressure. The absolute pressure is 0.15MPa. Solid sulfur is heated to 175°C in the evaporator. Nitrogen gas is bubbled through the evaporator at a flow rate of 1.75L / min under standard conditions to carry out saturated sulfur vapor. The mixed gas is heated to 175°C by the preheater before entering the reaction channel to control the sulfur vapor volume fraction at 0.9%. The temperature in the reaction channel is maintained at 185°C and the insulated wire core stays in the channel for 130s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank. The water temperature is controlled at 30°C to allow the insulation layer to cool and solidify rapidly, thus terminating all chemical reactions. (5) Wrap mica tape in two layers with an overlap rate of 28% around the cooled insulated core to form a fire-resistant layer; then extrude a nano-modified polyolefin sheath over the mica tape. The polyolefin sheath has a thickness of 1.6 mm. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath with a thickness of 1.5mm. After passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

[0032] Example 5 (1) According to the following mass parts, 100 parts of cross-linked polyethylene matrix resin, 10 parts of nano zinc oxide powder, 0.7 parts of antioxidant 1010, 0.5 parts of antioxidant 168, 1.0 part of dicumyl peroxide, 0.5 parts of triallyl isocyanurate, and 0.3 parts of zinc stearate; put the above raw materials into a high-speed mixer and stir at room temperature for 25 minutes to make the nano zinc oxide and each additive uniformly dispersed; then feed the mixture into a twin-screw extruder and melt-blend and granulate at 145°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The temperature of the extruder head is controlled at 145°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel. The channel is 3m long and is kept at atmospheric pressure to slightly positive pressure. The absolute pressure is 0.15MPa. Solid sulfur is placed in the evaporator and heated to 180°C. Nitrogen gas is bubbled through the evaporator at a flow rate of 2.0L / min under standard conditions to carry out saturated sulfur vapor. The mixed gas is preheated to 180°C before entering the reaction channel to control the sulfur vapor volume fraction at 1.0%. The temperature in the reaction channel is maintained at 190°C and the insulated wire core stays in the channel for 150s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank. The water temperature is controlled at 35°C to allow the insulation layer to cool and solidify rapidly, thus terminating all chemical reactions. (5) Wrap mica tape in two layers with an overlap rate of 30% around the cooled insulated wire core to form a fire-resistant layer; then extrude a nano-modified polyolefin sheath over the mica tape. The polyolefin sheath has a thickness of 1.6 mm. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath with a thickness of 1.5mm. After passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

[0033] Comparative Example 1 (1) According to the following mass parts, 100 parts of cross-linked polyethylene matrix resin, 0.5 parts of antioxidant 1010, 0.35 parts of antioxidant 168, 0.75 parts of dicumyl peroxide, 0.35 parts of triallyl isocyanurate, and 0.25 parts of zinc stearate; put the above raw materials into a high-speed mixer and stir at room temperature for 20 minutes to make the additives evenly dispersed; then feed the mixture into a twin-screw extruder and melt-blend and granulate at 140°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The temperature of the extruder head is controlled at 140°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel. The channel is 2.25m long and is kept at atmospheric pressure to slightly positive pressure. The absolute pressure is 0.125MPa. Solid sulfur is heated to 170°C in the evaporator. Nitrogen gas is bubbled through the evaporator at a flow rate of 1.5L / min under standard conditions to carry out saturated sulfur vapor. The mixed gas is heated to 170°C by the preheater before entering the reaction channel to control the sulfur vapor volume fraction at 0.75%. The temperature in the reaction channel is maintained at 175°C and the insulated wire core stays in the channel for 105s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank. The water temperature is controlled at 25°C to allow the insulation layer to cool and solidify rapidly. (5) Wrap mica tape in two layers with an overlap of 25% around the cooled insulated core to form a fire-resistant layer; then extrude a nano-modified polyolefin sheath over the mica tape. The polyolefin sheath has a thickness of 1.25 mm. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath with a thickness of 1.5mm. After passing the spark test and pressure resistance test, the finished cable is obtained.

[0034] Comparative Example 2 (1) Prepare insulating layer granules according to the same formula and process as step (1) in Example 3, that is, containing 8 parts of nano zinc oxide powder and other additives; (2) An insulating layer is formed using the same conductor insulation extrusion process as step (2) in Example 3; (3) The in-situ vulcanization reaction step is eliminated, that is, after the insulated wire core leaves the extruder head, it directly enters the cooling water tank, and the water temperature is controlled at 25°C to cool and solidify the insulation layer without passing through the closed reaction channel and sulfur vapor treatment. (4) Then, following the same process as steps (5) and (6) in Example 3, the mica tape is wrapped, the polyolefin sheath is extruded, the armor is braided, and the outer sheath is extruded to obtain the finished cable.

[0035] Comparative Example 3 (1) According to the following mass parts, 100 parts of cross-linked polyethylene matrix resin, 0.5 parts of antioxidant 1010, 0.35 parts of antioxidant 168, 0.75 parts of dicumyl peroxide, 0.35 parts of triallyl isocyanurate, and 0.25 parts of zinc stearate; put the above raw materials into a high-speed mixer and stir at room temperature for 20 minutes to make the additives evenly dispersed; then feed the mixture into a twin-screw extruder and melt-blend and granulate at 140°C to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head. The temperature of the extruder head is controlled at 140°C. The above-mentioned insulating layer granules are melted and extruded onto the surface of the conductor to form an insulating layer. The extrusion thickness of the insulating layer is 1 mm. (3) After the insulated wire core leaves the extruder head, it enters the cooling water tank directly. The water temperature is controlled at 25℃ to cool and solidify the insulation layer without any vulcanization treatment. (4) Then, following the same process as steps (5) and (6) in Example 3, the mica tape is wrapped, the polyolefin sheath is extruded, the armor is braided, and the outer sheath is extruded to obtain the finished cable.

[0036] Example of effect Table 1 below shows the performance analysis results of a composite explosion-proof control cable using Embodiments 1 to 5 and Comparative Examples 1 to 3 of the present invention.

[0037] Table 1 It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A composite explosion-proof control cable, characterized in that, The cable, from the inside out, comprises a copper conductor, an insulation layer, a mica tape wrapped fire-resistant layer, a nano-modified polyolefin sheath, a galvanized steel wire braided armor layer, and a flame-retardant polyvinyl chloride outer sheath. The insulating layer material is prepared by adding nano zinc oxide powder and modifying the surface of the insulating layer by introducing sulfur vapor through co-extrusion and in-situ vulcanization processes.

2. The composite explosion-proof control cable according to claim 1, characterized in that, The insulating layer, by weight, comprises 100 parts of cross-linked polyethylene matrix resin, 6-10 parts of nano zinc oxide powder, 0.3-0.7 parts of antioxidant 1010, 0.2-0.5 parts of antioxidant 168, 0.5-1.0 parts of dicumyl peroxide, 0.2-0.5 parts of triallyl isocyanurate, and 0.15-0.3 parts of zinc stearate.

3. A method for preparing a composite explosion-proof control cable, characterized in that, The preparation steps include the following: (1) Cross-linked polyethylene matrix resin, nano zinc oxide powder, antioxidant 1010, antioxidant 168, dicumyl peroxide, triallyl isocyanurate, and zinc stearate are put into a high-speed mixer and stirred at room temperature to make the nano zinc oxide and each additive uniformly dispersed; then the mixture is fed into a twin-screw extruder, melt-blended and granulated to obtain insulating layer granules; (2) After stranding multiple annealed copper conductors, they are fed into the extruder head, where the above-mentioned insulating granules are melted and extruded onto the surface of the conductor to form an insulating layer; (3) After the insulated wire core leaves the extruder head, it immediately enters the closed reaction channel, which is maintained at atmospheric pressure to slightly positive pressure. Solid sulfur is heated in the evaporator, and nitrogen gas is bubbled through the evaporator to carry out saturated sulfur vapor. The mixed gas is heated by the preheater before entering the reaction channel. The insulated wire core stays in the channel for 60s-150s. (4) After the insulated wire core that has completed the reaction leaves the reaction channel, it immediately enters the cooling water tank to allow the insulation layer to cool and solidify rapidly; (5) A double-layer mica tape is wrapped around the cooled insulated core to form a fire-resistant layer; then a nano-modified polyolefin sheath is extruded over the mica tape. (6) Galvanized steel wire is braided on the polyolefin sheath with a braiding density of 80% to form an armor layer; the outermost layer is extruded with flame-retardant polyvinyl chloride outer sheath, and after passing the spark test and pressure test, the composite explosion-proof control cable is obtained.

4. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (2), the thickness of the extruded insulating layer is 1 mm.

5. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (3), the reaction channel length is 1.5m-3m.

6. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (3), solid sulfur is placed in an evaporator and heated to 160℃-180℃.

7. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (3), the flow rate of nitrogen is 1.0 L / min to 2.0 L / min.

8. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (3), the preheater is heated to 160℃-180℃.

9. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (4), the water temperature of the cooling water tank is controlled between 15℃ and 35℃.

10. The method for preparing a composite explosion-proof control cable according to claim 3, characterized in that, In step (5), the thickness of the polyolefin sheath is 0.9mm-1.6mm.

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