A flame-retardant cable

Abstract

The application provides a kind of flame-retardant cable, relating to the technical field of cable, the flame-retardant cable, including conductor, the outside of conductor is sequentially sleeved with cooling layer, flame-retardant layer and protective layer;Cooling layer is phase change layer, its outside is provided with the microchannel that is evenly distributed in circumference, cooling layer expands and fills microchannel and is attached to the inner surface of flame-retardant layer after being heated and melted;Protective layer includes inner protective layer and outer protective layer, the inner side of inner protective layer is provided with corrugated groove containing microcapsule, microcapsule is broken under the extrusion of cooling layer and flame-retardant layer;Flame-retardant layer is porous structure, the liquid phase material of cooling layer and the liquid released by microcapsule are immersed in the pore of flame-retardant layer to form sealing layer.The application increases the flame-retardant effect of flame-retardant layer by the cooperation of cooling layer, flame-retardant layer and microcapsule, improves the flame-retardant capacity of cable when short circuit and overload.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to a flame-retardant cable. BACKGROUND

[0002] The flame-retardant cable refers to the cable that is ignited under the specified test conditions, and the flame spreading range is limited and the cable can be self-extinguished. The core function is to inhibit the spread of fire, and to delay the burning speed through special materials, so as to gain time for personnel evacuation and fire rescue.

[0003] The Chinese patent with the application number CN201780055161.2 discloses a self-extinguishing power cable with microcapsules, which comprises a conductive layer, an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a first neutral conductor water-blocking layer, a concentric neutral conductor, a second neutral conductor water-blocking layer and an outer sheath layer, wherein the microcapsules filled with active agents for extinguishing flame are coated on at least one of the first neutral conductor water-blocking layer and the second neutral conductor water-blocking layer; wherein the size of the microcapsules is 5-100 μm, and the allowable rupture temperature is in the range of 90-150 ℃; in the above-mentioned application, the microcapsules are arranged in the cable, so as to extinguish the flame of the cable and prevent the occurrence of serious fire.

[0004] Similar to the above-mentioned prior art, although the microcapsules can solve the fire caused by the short circuit of the cable, when the cable is overloaded for a long time, the temperature inside the cable will gradually rise, and if the temperature of the cable reaches the rupture temperature of the microcapsules at this time, and the cable does not catch fire, the microcapsules will break prematurely, and when the temperature of the cable reaches the ignition condition, the broken microcapsules cannot effectively retard the flame of the cable.

[0005] At the same time, when the cable with the microcapsules inside is laid, the microcapsules located at the bending part of the cable are easy to break under the action of extrusion force, resulting in that the cable loses the flame-retardant effect, and the cable can only retard the flame when the cable inside catches fire, and the heat dissipation performance is poor, and when the cable is overloaded for a long time, the cable cannot be effectively cooled.

[0006] Therefore, in order to solve the above-mentioned problems, the present application provides a flame-retardant cable, which aims to improve the flame-retardant ability of the cable caused by short circuit or overload. SUMMARY

[0007] The present application aims to provide a flame-retardant cable, which aims to solve the problem of self-ignition of the cable caused by short circuit or overload.

[0008] In order to achieve the above object, the present application adopts the following technical scheme: a flame-retardant cable comprising a conductor, characterized in that the conductor is externally sleeved with a cooling layer, a flame-retardant layer and a protective layer in sequence; the cooling layer is a phase change layer, and the outer side of the cooling layer is provided with microchannels uniformly distributed in the circumference; the cooling layer expands and fills the microchannels and adheres to the inner surface of the flame-retardant layer after being melted by heat; the protective layer comprises an inner protective layer and an outer protective layer, the inner side of the inner protective layer is provided with corrugated grooves containing microcapsules, and the microcapsules are broken under the extrusion of the cooling layer and the flame-retardant layer; the flame-retardant layer has a porous structure, and the liquid phase material of the cooling layer and the liquid released by the microcapsules are jointly immersed in the pores of the flame-retardant layer to form a sealing layer.

[0009] A further technical scheme of the present application is that the cooling layer changes from a solid phase to a liquid phase after the temperature rises, and the microchannels provide expansion space when the cooling layer melts.

[0010] A further technical scheme of the present application is that the outer protective layer is arranged on the outer side of the inner protective layer, and a plurality of microcapsules are arranged in the grooves.

[0011] A further technical scheme of the present application is that the outer surface of the conductor is coated with an insulating layer, the outer side of the insulating layer is sleeved with a shielding layer, a filling layer is arranged between the insulating layer and the shielding layer, and the insulating layer, the filling layer and the shielding layer are located between the conductor and the cooling layer.

[0012] A further technical scheme of the present application is that the conductor comprises a cable core composed of one or more strands of conductive material, and the surface of the conductor is coated with a boron nitride nanosheet coating.

[0013] A further technical scheme of the present application is that the insulating layer comprises a cross-linked polyethylene matrix, magnesium hydroxide nanoparticles and carbon nanotubes.

[0014] A further technical scheme of the present application is that the shielding layer has a grid structure, and the outer surface of the shielding layer is coated with an electromagnetic interference coating.

[0015] A further technical scheme of the present application is that the flame-retardant layer realizes double flame retardation in cooperation with the cooling layer and the microcapsules.

[0016] A further technical scheme of the present application is that the outer protective layer comprises polyvinyl chloride and graphene, and the inner protective layer comprises thermoplastic polyurethane and nanosilica.

[0017] A further technical scheme of the present application is that the radial section of the groove is corrugated, and the interior of the microcapsule is filled with a high-temperature-resistant and electrically insulating liquid.

[0018] The beneficial effects are:

[0019] 1. The present application is provided with microcapsules and grooves, cooperates with the inner protective layer, when the cable is extruded or twisted by external force, the corrugated structure can disperse the local pressure and reduce the risk of cracking of the protective layer; and the grooves provide buffer space for the microcapsules to avoid mechanical impact causing the capsules to break prematurely, at the same time the microcapsules can cool the flame retardant layer, realize the cooperation of flame retardant, achieve the purpose of enhancing the protection ability and flame retardant.

[0020] 2. The present application is provided with cooling layer and microcapsules, which jointly act on the flame retardant layer, the porous ceramicized silicone rubber matrix is used as the flame retardant layer, when the phase change material of the cooling layer melts and expands, it is immersed in the flame retardant layer together with the silicone oil released by the microcapsules, forming a dense sealing layer. This sealing layer can isolate oxygen contact and inhibit the combustion chain reaction, thereby improving the flame retardant ability of the cable when facing short circuit or overload.

[0021] 3. The present application is provided with cooling layer, microcapsules and flame retardant layer, which improves the ability of the cable to respond quickly when short circuit and to protect continuously when overload; when the cable is short-circuited, the current increases suddenly, causing the local temperature to exceed the melting point of paraffin, the cooling layer rapidly phase changes and absorbs heat, forming a "temperature platform" effect to inhibit temperature rise, and at the same time, directional fire extinguishing is carried out, that is, the microcapsules at the corresponding position break, release silicone oil for directional cooling and fill the pores to prevent flame spread; when the cable is continuously overloaded, the cooling layer continuously melts to absorb heat, delaying the temperature rise rate, and the liquid paraffin of the cooling layer and the silicone oil released by the broken microcapsules together impregnate the flame retardant layer, forming a dynamic sealing layer to block heat transfer. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of embodiment one of the present application.

[0023] Figure 2 is a structural schematic diagram of the microchannel in the specific embodiment of the present application.

[0024] Figure 3 is a structural schematic diagram of embodiment two of the present application.

[0025] Figure 4 is a structural schematic diagram of the groove in the specific embodiment of the present application.

[0026] Figure 5 is a structural schematic diagram of the present application Figure 3 is a local enlarged view of A in the present application.

[0027] REFERENCE NUMERALS:

[0028] 1, conductor; 2, insulating layer; 21, filling layer; 3, shielding layer; 4, cooling layer; 41, microchannel; 5, flame retardant layer; 6, protective layer; 61, outer protective layer; 62, inner protective layer; 621, groove; 622, microcapsule. DETAILED DESCRIPTION

[0029] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1

[0031] To improve the flame retardancy and flexibility of flame retardant cables, such as Figure 1 and Figure 2 As shown, in the first embodiment of the present invention, a flame-retardant cable is proposed, including a conductor 1, the outside of the conductor 1 is sequentially covered with a cooling layer 4 and a flame-retardant layer 5, the outside of the flame-retardant layer 5 is covered with a protective layer 6, the cooling layer 4 is a phase change layer, and the outside of the cooling layer 4 is provided with a plurality of microchannels 41. After being subjected to high temperature, the cooling layer 4 melts and expands and adheres to the inner surface of the flame-retardant layer 5 to form a sealing layer.

[0032] It should be noted that the setting of the microchannel 41 increases the flexibility of the cable. When the cable is locally twisted during installation or movement, the setting of the microchannel 41 can solve the problem of excessive torsional stress of the cable causing rupture in the torsional area of ​​the cable. At the same time, the setting of the microchannel 41 leaves expansion space for the cooling layer 4. After melting, the cooling layer 4 expands in volume and fills the microchannel 41, so that the melted cooling layer 4 adheres to the inner side of the flame retardant layer 5, thereby increasing the heat transfer performance of the flame retardant layer 5.

[0033] In this embodiment, the cooling layer 4 changes from a solid phase to a liquid phase after the temperature rises, and a plurality of microchannels 41 are evenly distributed on the outer side of the cooling layer 4 in a circumferential manner.

[0034] It should be noted that the cooling layer 4 can be a phase change layer made of organic paraffin as a phase change material and expanded graphite as a supporting structure. Paraffin has a high latent heat of phase change. When the temperature rises to the range of 47°-64°, the paraffin enters the main melting stage. The heat is mainly used to destroy the van der Waals force between molecules rather than continue to increase the temperature. Therefore, the temperature remains relatively stable, forming a "temperature platform" phenomenon, which plays a role in regulating the temperature. Expanded graphite has good thermal conductivity and supporting function, which can improve the thermal conductivity and stability of the phase change layer.

[0035] In this embodiment, the outer surface of the conductor 1 is covered with an insulating layer 2, the outer surface of the insulating layer 2 is provided with a shielding layer 3, a filling layer 21 is provided between the insulating layer 2 and the shielding layer 3, and the insulating layer 2, the filling layer 21 and the shielding layer 3 are located between the conductor 1 and the cooling layer 4.

[0036] The conductor 1 includes one or more cable cores composed of a winding group of conductive material, and the surface of the conductor 1 is coated with a boron nitride nanosheet coating. Exemplarily, the conductor 1 can be a silver-plated copper core, which has good electrical conductivity and thermal conductivity, and can quickly transmit current and conduct generated heat. The thickness of the boron nitride nanosheet coating on the conductor 1 is 3-13 μm, and the boron nitride nanosheet coating has high thermal conductivity and chemical stability, and forms a directional arrangement structure by chemical vapor deposition method, which can further improve the axial thermal conductivity of the conductor 1 and accelerate the heat transfer speed.

[0037] The insulating layer 2 includes a cross-linked polyethylene matrix, magnesium hydroxide nanoparticles and carbon nanotubes. Exemplarily, the insulating layer 2 forms a three-dimensional heat-conducting network by electron beam irradiation, and the mass fraction of the magnesium hydroxide nanoparticles can be 10-20%, and the mass fraction of the carbon nanotubes can be 3-5%.

[0038] It should be noted that the magnesium hydroxide nanoparticles have good flame retardant performance, can decompose and absorb heat when a fire occurs, and can inhibit the spread of flames. The carbon nanotubes have excellent thermal conductivity, can improve the thermal conductivity of the insulating layer 2, and promote the dissipation of heat. The three-dimensional heat-conducting network formed by electron beam irradiation enables heat to be quickly transferred in the insulating layer 2, thereby improving the heat dissipation capacity of the insulating layer 2. In addition, the filling layer 21 can further enhance the mechanical properties and protection performance of the insulating layer 2.

[0039] The shielding layer 3 has a grid structure, and the outer surface of the shielding layer 3 is coated with an electromagnetic interference coating. The shielding layer 3 can be made of metal, and the grid structure can effectively shield external electromagnetic interference and protect the signal transmission inside the cable from interference. The electromagnetic interference coating can further enhance the shielding effect of the shielding layer 3 and improve the anti-interference ability of the cable.

[0040] The flame-retardant layer 5 has a porous structure and can realize double flame retardation in cooperation with the cooling layer 4 and the microcapsule 622. Exemplarily, the flame-retardant layer 5 can be a porous ceramic layer made of a ceramicized silicone rubber matrix and compounded with zinc borate or melamine polyphosphate. The porosity of the porous ceramic layer is ≥60%, the ceramicized silicone rubber matrix has good flexibility and flame retardant performance, and can quickly ceramicize to form a hard ceramic protective layer to prevent the spread of flames when a fire occurs. Zinc borate and melamine polyphosphate have a synergistic flame-retardant effect, which can improve the flame-retardant effect of the flame-retardant layer 5. The high porosity of the porous ceramic layer makes it have good heat insulation performance, which can further reduce the temperature inside the cable and improve the flame-retardant performance of the cable.

[0041] In this embodiment, the conductor 1 is set as a silver-plated copper core coated with a boron nitride nanosheet coating, a shielding layer 3 is set outside the insulating layer 2, and a cooling layer 4, a flame retardant layer 5 and a protective layer 6 are sequentially arranged outside the shielding layer 3. The cooling layer 4 is a phase change layer made of organic paraffin as a phase change material and expanded graphite as a supporting structure. A plurality of microchannels 41 are provided on the outside of the cooling layer 4. The above arrangement improves the thermal management and heat dissipation capabilities of the cable, reduces the possibility of cable combustion, enhances the cable's anti-electromagnetic interference capability, improves the cable's flexibility, and prevents the cooling layer 4 from excessive expansion and damaging the flame retardant layer 5.

[0042] Example 2

[0043] In actual use, cables can short-circuit or overload, causing internal temperature increases and potentially causing spontaneous combustion. When a cable short-circuits, the resistance between conductors 1 approaches zero, and the current instantly reaches 10-1000 times its normal value. According to Joule's law, the square of the current increases, leading to an exponential increase in heat, which can cause spontaneous combustion. When a cable is overloaded, the heat generated by the resistance of conductor 1 cannot be dissipated in time, causing the temperature to continue to rise, and the insulation layer 2 begins to decompose. If it reaches its ignition point, it can directly ignite.

[0044] In order to solve the above technical problems, Figures 3 to 5 As shown, in another embodiment of the present invention, a plurality of microcapsules 622 are provided on the inner side of the protective layer 6 of the flame-retardant cable. The microchannels 41 and the microcapsules 622 can assist the flame-retardant layer 5 in improving the flame-retardant effect of the cable when the cable is short-circuited and overloaded. That is, the liquid phase material of the cooling layer 4 and the liquid released by the microcapsules 622 are immersed in the pores of the flame-retardant layer 5 together to form a sealing layer, thereby improving the flame-retardant effect.

[0045] The protective layer 6 also includes an inner protective layer 62 that is sleeved over the flame-retardant layer 5. The outer protective layer 61 is sleeved on the outer side of the inner protective layer 62. The inner side of the inner protective layer 62 is provided with a plurality of grooves 621 that match the microcapsules 622. The microcapsules 622 are respectively located in the corresponding grooves 621. The inner protective layer 62 with the grooves 621 and the microcapsules 622 can cushion the impact of the cable, thereby protecting the cable.

[0046] The outer protective layer 61 includes polyvinyl chloride and graphene, and the inner protective layer 62 includes thermoplastic polyurethane and nano-silicon dioxide.

[0047] It should be noted that polyvinyl chloride has excellent mechanical properties and chemical corrosion resistance, and graphene has excellent electrical and thermal conductivity, which can improve the strength and heat dissipation performance of the outer protective layer 61. Thermoplastic polyurethane has good flexibility and wear resistance, and nano-silica can improve the hardness and aging resistance of the inner protective layer 62. The outer protective layer 61 and the inner protective layer 62 work together to achieve synergistic mechanical protection and flame retardancy.

[0048] The radial section of the groove 621 is corrugated, the microcapsules 622 are filled with high-temperature-resistant and electrically insulating liquid, and the plurality of microcapsules 622 are uniformly distributed in the interior of the groove 621. The high-temperature-resistant and electrically insulating liquid filled in the microcapsules 622 can be silicone oil. The microcapsules 622 can release silicone oil when broken, fill the cracks of the inner protective layer 62, and isolate oxygen, achieving the purposes of flame retardation and enhanced protection.

[0049] It should be noted that the radial section of the groove 621 is corrugated, which cooperates with the inner protective layer 62 to disperse local pressure and reduce the risk of cracking of the protective layer when the cable is extruded or twisted by external force. In addition, the groove 621 provides a buffer space for the microcapsules 622 to avoid premature rupture of the microcapsules 622 caused by mechanical impact.

[0050] In this embodiment, by arranging the inner protective layer 62 in the interior of the outer protective layer 61, arranging the groove 621 in the interior of the inner protective layer 62, and arranging the microcapsules 622 filled with silicone oil in the interior of the groove 621, the cable can be protected by the inner protective layer 62 and the microcapsules 622. When the inner protective layer 62 cracks due to aging, the corresponding microcapsules 622 will be torn, the microcapsules 622 release silicone oil, and the silicone oil fills the cracks through capillary action, restoring the integrity of the protection and prolonging the service life of the cable. The microcapsules 622 achieve the purposes of enhanced protection and flame retardation.

[0051] It should be noted that the flame-retardant layer 5 is made of porous ceramic silicone rubber matrix (porosity ≥ 60%). When the phase change material (such as paraffin) of the cooling layer 4 melts and expands, it is immersed in the pores together with the silicone oil released by the microcapsules 622, forming a dense sealing layer. This sealing layer can isolate oxygen and inhibit the combustion chain reaction.

[0052] At the same time, zinc borate and melamine polyphosphate are added to the flame-retardant layer 5 to form a synergistic flame-retardant effect with the silicone oil. Zinc borate decomposes into glassy borate at high temperature, covering the surface of the material. Melamine polyphosphate releases inert gas to dilute oxygen. Silicone oil penetrates to enhance the sealing property, and the three work together to improve the limiting oxygen index, thereby improving the flame-retardant effect.

[0053] In addition, when the cable is short-circuited, the temperature in the cable rises sharply, and the cooling layer 4 is in a solid-liquid mixed state. The solid in the cooling layer 4 breaks the microcapsules 622 in the corresponding area through the flame-retardant layer 5, and the silicone oil in the microcapsules 622 flows out to cool the flame-retardant layer 5.

[0054] When the cable is overloaded, the temperature inside the cable continues to rise, and after the melting point of the temperature paraffin, the paraffin of the cooling layer 4 absorbs heat and melts, and when the paraffin melts, the volume will expand significantly (expansion rate about 10%-20%), so that the cooling layer 4 expands, and the melted liquid of the cooling layer 4 will immerse the fire-retardant layer 5, so that the fire-retardant layer 5 forms a sealed state to isolate external air, and at the same time, the cooling layer 4 will extrude the fire-retardant layer 5, and then extrude the microcapsule 622, so that the microcapsule 622 is extruded and broken, and the silicone oil in the microcapsule 622 will wet the fire-retardant layer 5, which cools the fire-retardant layer 5 and further forms a sealed state to isolate external air, thereby improving the fire-retardant effect.

[0055] When the cable is overloaded, the temperature inside the cable continues to rise, and after the melting point of the temperature paraffin, the paraffin of the cooling layer 4 absorbs heat and melts, and when the paraffin melts, the volume will expand significantly (expansion rate about 10%-20%), so that the cooling layer 4 expands, and the melted liquid of the cooling layer 4 will immerse the fire-retardant layer 5, so that the fire-retardant layer 5 forms a sealed state to isolate external air, and at the same time, the cooling layer 4 will extrude the fire-retardant layer 5, and then extrude the microcapsule 622, so that the microcapsule 622 is extruded and broken, and the silicone oil in the microcapsule 622 will wet the fire-retardant layer 5, which cools the fire-retardant layer 5 and further forms a sealed state to isolate external air, thereby improving the fire-retardant effect.

[0056] The cooling layer 4, the fire-retardant layer 5 and the microcapsule 622 are arranged, so that the ability to cope with the self-ignition caused by the temperature rise inside the cable is improved.

[0057] The above only describes the preferred embodiments of the present application, but the protection scope of the present application is not limited to this, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A flame-retardant cable comprising a conductor, characterized in that: The conductor is covered with a cooling layer, a flame retardant layer and a protective layer in sequence on the outside; The cooling layer is a phase change layer, and microchannels are evenly distributed on its outer side. When the cooling layer is heated and melted, it expands and fills the microchannels and adheres to the inner surface of the flame retardant layer. When the temperature rises, the cooling layer changes from a solid phase to a liquid phase. The microchannels provide expansion space when the cooling layer melts. The protective layer includes an inner protective layer and an outer protective layer. The inner side of the inner protective layer is provided with a corrugated groove containing microcapsules. The microcapsules are broken under the pressure of the cooling layer and the flame retardant layer. The radial cross-section of the groove is corrugated. The interior of the microcapsules is perfused with a high-temperature resistant and electrically insulating liquid. The flame retardant layer has a porous structure, and the liquid phase material of the cooling layer and the liquid released by the microcapsules are immersed in the pores of the flame retardant layer to form a sealing layer; When the cable is short-circuited, the temperature of the cable rises rapidly in a certain area. When the cooling layer faces the drastic temperature change, it is in a solid-liquid mixed state. The solid matter of the cooling layer squeezes the microcapsules in the corresponding area through the flame retardant layer, thereby cooling the flame retardant layer. When the cable is overloaded but the temperature does not reach the fire condition, the temperature inside the cable continues to rise, the cooling layer continues to melt and expand, and the melted liquid of the cooling layer adheres to the inner side of the flame retardant layer, improving the heat dissipation performance of the flame retardant layer; When the cable is continuously overloaded and heated to the point of ignition, the melted liquid in the cooling layer penetrates into the flame retardant layer, sealing the flame retardant layer and isolating it from the outside air. At the same time, the cooling layer expands and squeezes the flame retardant layer, thereby squeezing the microcapsules. After the microcapsules are squeezed, the silicone oil inside the microcapsules soaks the flame retardant layer, cooling the flame retardant layer while further sealing it and isolating it from the outside air, thereby improving the flame retardant effect. The flame retardant layer cooperates with the cooling layer and microcapsules to achieve double flame retardancy.

2. The flame-retardant cable according to claim 1, characterized in that: The outer protective layer is arranged on the outer side of the inner protective layer, and a plurality of microcapsules are arranged in the groove.

3. The flame-retardant cable according to claim 1, characterized in that: The outer surface of the conductor is covered with an insulating layer, the outer surface of the insulating layer is covered with a shielding layer, a filling layer is provided between the insulating layer and the shielding layer, and the insulating layer, the filling layer and the shielding layer are located between the conductor and the cooling layer.

4. The flame-retardant cable according to claim 3, characterized in that: The conductor comprises a cable core formed by winding one or more strands of conductive material, and the surface of the conductor is coated with a boron nitride nanosheet coating.

5. The flame-retardant cable according to claim 3, characterized in that: The insulating layer includes a cross-linked polyethylene matrix, magnesium hydroxide nanoparticles and carbon nanotubes.

6. The flame-retardant cable according to claim 3, characterized in that: The shielding layer is a grid structure, and the outer surface of the shielding layer is coated with an electromagnetic interference coating.

7. The flame-retardant cable according to claim 1, characterized in that: The outer protective layer comprises polyvinyl chloride and graphene, and the inner protective layer comprises thermoplastic polyurethane and nano-silicon dioxide.

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