Highly weather-resistant flame-retardant cable insulation protective shell

Abstract

The present invention provides a highly weather-resistant and flame-retardant cable insulation protective shell, comprising two outer sheaths interconnected by flanges, wherein the matrix of the outer sheath is a composite of silane-grafted EPDM and polyaryletherketone, and carbon quantum dots are uniformly dispersed and embedded in the polyaryletherketone of the matrix; the outer sheath comprises an inner layer, an intermediate layer, and an outer layer arranged in sequence from the inside to the outside, the inner surface of the inner layer is provided with a spiral groove, the intermediate layer is a honeycomb plate, and the wall thickness of each honeycomb hole gradually increases from the outer layer to the inner layer, the honeycomb wall of each honeycomb hole is wavy, and a phase change material containing zinc borate, phosphorus nitrogen, and kaolin is poured into each honeycomb hole, the phase change material melts to absorb heat when the temperature reaches a first set value, the outer layer is a scale layer that shields the intermediate layer, and each scale is embedded with a shape memory alloy wire, which contracts to close the scale when the temperature reaches a second set value, the second set value being less than the first set value, and the zinc borate, phosphorus nitrogen, and kaolin seep outward when the scales are closed.

Description

Technical Field

[0001] The invention relates to the technical field of protective hardware, in particular to a highly weather-resistant and flame-retardant cable insulation protective shell. Background Art

[0002] Cable insulation shields connect or segment the metal sheaths of high-voltage cables. They also provide electrical insulation, external sealing, grounding, and mechanical protection for intermediate joints. In recent years, as power companies have increased their requirements for cable accessories, so too have their demands for flame retardancy. This has prompted suppliers to optimize and upgrade the insulation layer of traditional copper shields using new composite materials to achieve higher flame retardancy ratings.

[0003] However, there is still room for improvement in the weather resistance and flame retardancy of cable insulation protective sheaths. This is because the traditional blending process results in a weak interface between the flame retardant and the polymer matrix, which easily causes microcracks under the influence of ultraviolet rays. In addition, the homogeneous structure produces isotropic expansion during temperature cycling, which easily leads to interfacial delamination. This is the main reason why weather resistance can be further improved. Because a single-component flame retardant system cannot achieve a "gas phase-condensed phase" synergistic barrier, and the smooth surface structure cannot form an effective droplet barrier, a "chimney effect" will occur during vertical combustion. In this case, the flame heats the air to form an updraft, generating strong convection within the smooth channel, continuously drawing in fresh oxygen and exhausting high-temperature smoke, resulting in a doubling of combustion intensity. This is the main reason why flame retardancy can be further improved. Summary of the Invention

[0004] The present invention aims to solve the above technical problems and provide a highly weather-resistant and flame-retardant cable insulation protective shell.

[0005] The technical solution of the present invention is that the highly weather-resistant and flame-retardant cable insulation protective shell includes two outer sheaths connected to each other by a flange, the matrix of the outer sheath is a composite of silane-grafted EPDM and polyaryletherketone, and carbon quantum dots are uniformly dispersed and embedded in the polyaryletherketone of the matrix;

[0006] The outer protective layer includes an inner layer, an intermediate layer, and an outer layer arranged in sequence from the inside to the outside, the inner surface of the inner layer is provided with a spiral groove, the intermediate layer is a honeycomb plate, and the wall thickness of each honeycomb hole gradually increases from the outer layer to the inner layer, the honeycomb wall of each honeycomb hole is wavy, and a phase change material containing zinc borate, phosphorus nitrogen, and kaolin is poured into each honeycomb hole, and the phase change material melts to absorb heat when the temperature reaches a first set value, the outer layer is a scale layer that shields the intermediate layer, and each scale is embedded with a shape memory alloy wire, and the shape memory alloy wire contracts to close the scale when the temperature reaches a second set value, and the second set value is less than the first set value, and the zinc borate, phosphorus nitrogen, and kaolin seep outward when the scale is closed;

[0007] Among them, zinc borate decomposes at high temperature to form boron oxide glass phase, which reacts with carbides contained in the matrix to form a ceramic layer. Phosphorus and nitrogen decompose at high temperature to form phosphoric acid, which reacts with aluminum hydroxyl contained in kaolin to form a carbon layer.

[0008] As an embodiment, the carbon quantum dots account for 0.5% of the total mass of the composite.

[0009] As an embodiment, the phase change material is a composite material of paraffin wax and expanded graphite.

[0010] As an embodiment, an aerogel insulation layer is provided at the trough of the honeycomb wall.

[0011] As an embodiment, the mass ratio of the zinc borate to the kaolin is 3:1.

[0012] As an embodiment, the shape memory alloy wire is made of nickel-titanium alloy.

[0013] As an embodiment, the inner layer is provided with a thermochromic temperature indicating material, and observation windows are provided at corresponding positions of the middle layer and the outer layer.

[0014] As an embodiment, it also includes a protective copper shell arranged in the outer protective layer.

[0015] As an embodiment, a grounding terminal is provided on the outer protective layer, and the grounding terminal is connected to the protective copper shell.

[0016] As an embodiment, the wall thickness of the honeycomb holes connecting the outer layer is 50 μm, and the wall thickness of the honeycomb holes connecting the inner layer is 200 μm.

[0017] Compared with the prior art, the beneficial effect of the present invention is that the matrix of the outer sheath of the highly weather-resistant and flame-retardant cable insulation protective shell improves compatibility by introducing functional groups (silanes) to form a more stable multiphase system. EPDM has the characteristics of flexibility and aging resistance, and polyaryletherketone has the characteristics of rigidity and high heat resistance. Functional groups are introduced into the EPDM molecular chain to improve its compatibility with polyaryletherketone, thereby making the matrix of the outer sheath both flexible and heat-resistant. Strengthening the interface by silane grafting can reduce phase interface defects and inhibit crack propagation caused by thermal expansion differences at high temperatures. The embedded carbon quantum dots have a wide absorption spectrum and can absorb ultraviolet light. They convert high-energy ultraviolet rays into low-energy visible light or release heat energy through the fluorescence effect, reducing the damage of ultraviolet rays to the polymer chain. Therefore, the weather resistance of the cable insulation protective shell is improved through material improvements.

[0018] In addition to improvements in materials, the substrate also features structural improvements, including a layered structure consisting of an inner layer, an intermediate layer, and an outer layer. The spiral grooves in the inner layer guide the combustion gases into a Coanda-effect vortex, extending the flame path. The intermediate layer is a composite structure of a honeycomb panel and a corrugated plate. Specifically, the sidewalls of each honeycomb cell in the honeycomb panel are wavy, allowing the cells to be filled with a phase-change material containing zinc borate, phosphorus nitrogen, and kaolin. The phase-change material melts at a first set temperature, at which point the scales in the outer layer already possess contraction potential. This is because the shape memory alloy wire contracts at a second set temperature, which is lower than the first set temperature. Consequently, the closing of the scales allows the zinc borate, phosphorus nitrogen, and kaolin to seep outward with the melt. Zinc borate and phosphorus nitrogen are both flame retardants. Zinc borate decomposes at high temperatures to form a boron oxide glass phase, which reacts with carbides in the substrate to form a ceramic layer. This ceramic layer isolates oxygen and reflects heat, terminating the combustion chain reaction. Phosphorus and nitrogen decompose at high temperatures to form phosphoric acid, which reacts with the aluminum hydroxyl groups in kaolin to form a carbon layer. This provides the incremental carbon layer needed to form the ceramic layer, thereby strengthening the ceramic layer and providing synergistic flame retardancy. This shows that through the combined improvements in the materials and structure of the outer sheath, the inner, middle, and outer layers all respond to high temperatures, achieving simultaneous flame retardancy inside and out. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic structural diagram of a highly weather-resistant and flame-retardant cable insulation protective cover provided in an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the outer sheath and the middle layer of the highly weather-resistant and flame-retardant cable insulation protective shell provided by an embodiment of the present invention;

[0021] Figure 3 This is a schematic cross-sectional view of the outer sheath and inner layer of the highly weather-resistant and flame-retardant cable insulation protective shell provided by an embodiment of the present invention.

[0022] In the figure: 1. Flange; 2. Outer protective layer; 3. Inner layer; 4. Middle layer; 5. Outer layer; 6. Spiral groove; 7. Honeycomb hole; 8. Scale; 9. Observation window; 10. Protective copper shell; 11. Grounding terminal. DETAILED DESCRIPTION

[0023] The above and other embodiments and advantages of the present invention are clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments.

[0024] In one embodiment, Figures 1 to 3 shown.

[0025] The highly weather-resistant and flame-retardant cable insulation protective shell provided in this embodiment includes two outer sheaths 2 connected to each other by a flange 1. The matrix of the outer sheath 2 is a composite of silane-grafted EPDM and polyaryletherketone, and carbon quantum dots are uniformly dispersed in the polyaryletherketone of the matrix; the outer sheath 2 includes an inner layer 3, an intermediate layer 4, and an outer layer 5 arranged in sequence from the inside to the outside. The inner surface of the inner layer 3 is provided with a spiral groove 6. The intermediate layer 4 is a honeycomb board, and the wall thickness of each honeycomb hole 7 gradually increases from the outer layer 5 to the inner layer 3. The honeycomb wall of each honeycomb hole 7 is wavy, and each honeycomb hole 7 is filled with zinc borate, phosphorus nitrogen, and The phase change material of kaolin melts to absorb heat when the temperature reaches a first set value. The outer layer 5 is a scale layer that shields the middle layer 4. Each scale 8 is embedded with a shape memory alloy wire. The shape memory alloy wire contracts to close the scale 8 when the temperature reaches a second set value. The second set value is less than the first set value. Zinc borate, phosphorus and nitrogen, and kaolin seep outward when the scale 8 is closed; among them, zinc borate decomposes at high temperature to form a boron oxide glass phase, which reacts with the carbide contained in the matrix to form a ceramic layer. Phosphorus and nitrogen decompose at high temperature to form phosphoric acid, which reacts with the aluminum hydroxyl contained in the kaolin to form a carbon layer.

[0026] In this embodiment, compared with the traditional blending process, that is, each component is dispersed by melting or mechanical shearing, and the interface is mainly physically bonded. The matrix of the outer sheath 2 of the cable insulation protective shell improves compatibility by introducing functional groups (silanes) to form a more stable multiphase system. EPDM has the characteristics of flexibility and aging resistance, and polyaryletherketone has the characteristics of rigidity and high heat resistance. Functional groups are introduced into the EPDM molecular chain to improve its compatibility with polyaryletherketone, so that the matrix of the outer sheath 2 has both flexibility and heat resistance. Strengthening the interface by silane grafting can reduce phase interface defects and inhibit crack propagation caused by thermal expansion differences at high temperatures. The embedded carbon quantum dots have a wide absorption spectrum and can absorb ultraviolet light. They convert high-energy ultraviolet rays into low-energy visible light or heat energy release through the fluorescence effect, reducing the damage of ultraviolet rays to the polymer chain. Therefore, the cable insulation protective shell has improved weather resistance through material improvements.

[0027] In addition to material improvements, the substrate also features structural improvements, with a layered structure consisting of an inner layer 3, an intermediate layer 4, and an outer layer 5. The spiral grooves 6 in the inner layer 3 guide the combustion gases to form Coanda-effect vortices, extending the flame path. These spiral grooves 6 are arranged spirally along the axis of the outer protective layer 2. The intermediate layer 4 is a composite structure of a honeycomb panel and a corrugated panel. The sidewalls of each honeycomb cell 7 in the honeycomb panel are wavy, allowing for the infusion of a phase change material containing zinc borate, phosphorus nitrogen, and kaolin. The honeycomb panel is used because its cells 7 offer lightweight and high compressive strength, facilitating the infusion of the phase change material containing zinc borate, phosphorus nitrogen, and kaolin. The wall thickness of each honeycomb cell 7 gradually increases from the outer layer 5 to the inner layer 3, forming a continuously varying thickness gradient. This thin-walled design of the outer layer 5 reduces weight while meeting the surface flexibility requirements, namely, the closed extrusion of the flaky layer. The thick wall design of the inner layer 3 enhances the load-bearing capacity and prevents fracture caused by stress concentration. Phase change material refers to a substance that absorbs heat by changing its physical state at a specific temperature. The phase change material melts when the temperature reaches a first set value. At this time, the scales 8 of the outer layer 5 already have contraction potential energy because the shape memory alloy wire contracts when the temperature reaches a second set value, and the second set value is less than the first set value. Therefore, the closure of the scales 8 causes zinc borate, phosphorus nitrogen, and kaolin to seep outward with the melt. Zinc borate and phosphorus nitrogen are both flame retardants. Zinc borate decomposes at high temperatures to form a boron oxide glass phase, which reacts with the carbide contained in the matrix to form a ceramic layer. The ceramic layer can isolate oxygen and reflect heat, terminating the combustion chain reaction. Phosphorus nitrogen decomposes at high temperatures to form phosphoric acid, which reacts with the aluminum hydroxyl contained in kaolin to form a carbon layer, providing the incremental carbon layer required to form the ceramic layer, thereby strengthening the ceramic layer for synergistic flame retardancy. It can be seen that the outer protective layer 2 is improved in material and structure, so that the inner layer 3, the middle layer 4, and the outer layer 5 can respond to high temperature together, achieving synchronous flame retardancy inside and outside.

[0028] Therefore, the highly weather-resistant and flame-retardant cable insulation protective shell has significantly improved weather resistance and flame retardancy through improvements in materials and structure.

[0029] In one embodiment, the carbon quantum dots in the highly weather-resistant and flame-retardant cable insulation protective shell account for 0.5% of the total mass of the composite.

[0030] In this embodiment, by precisely controlling the amount of carbon quantum dots, the content is set to 0.5wt%. This not only protects the material from light aging through the ultraviolet conversion function of the carbon quantum dots, that is, absorbing ultraviolet light and converting it into harmless visible light and heat energy, but also avoids the uneven dispersion and mechanical property degradation caused by excessive addition.

[0031] In one embodiment, the phase change material of the highly weather-resistant and flame-retardant cable insulation protective shell is a composite material of paraffin and expanded graphite.

[0032] In this embodiment, paraffin wax provides heat storage and temperature regulation. Specifically, it absorbs heat through its phase transition from solid to liquid, mitigating high temperatures accumulated during cable operation. Expanded graphite, a porous carrier, encapsulates the paraffin wax, preventing leakage. It also enhances the thermal conductivity of the composite material, promoting even heat distribution.

[0033] In one embodiment, the highly weather-resistant and flame-retardant cable insulation protective shell has an aerogel insulation layer provided at the trough of the honeycomb wall.

[0034] In this embodiment, the troughs of the corrugated structure are weak points where stress concentrates and heat transfer occurs. Filling these areas with aerogel effectively blocks the transfer of high external temperatures to the middle and inner layers. Furthermore, due to its extremely low density, aerogel avoids adding weight to the overall structure.

[0035] In one embodiment, the mass ratio of zinc borate to kaolin in the highly weather-resistant and flame-retardant cable insulation protective shell is 3:1.

[0036] In this embodiment, by setting the mass ratio of zinc borate to kaolin at 3:1, 3 parts of zinc borate decompose at high temperature to form a boron oxide glass layer, isolating it from oxygen, while 1 part of kaolin acts as a catalyst to promote carbonization and enhance the strength of the ceramic layer. This optimized 3:1 ratio ensures sufficient reaction between the two and avoids embrittlement of the material caused by excessive kaolin.

[0037] In one embodiment, the shape memory alloy wire of the highly weather-resistant and flame-retardant cable insulation protective shell is made of nickel-titanium alloy.

[0038] In this embodiment, the shape memory alloy wire, made of nickel-titanium alloy, triggers a shape memory effect at a specific temperature. The wire contracts, driving the scales 8 of the scale layer to close, thereby actively enhancing thermal insulation and sealing. Nickel-titanium alloy is fatigue-resistant and corrosion-resistant, making it suitable for long-term outdoor use.

[0039] In one embodiment, the highly weather-resistant and flame-retardant cable insulation protective shell has an inner layer 3 provided with a thermochromic temperature-indicating material, and observation windows 9 are provided at corresponding positions of the middle layer 4 and the outer layer 5 .

[0040] Thermochromic temperature-indicating material (such as a cobalt salt complex) is positioned within inner layer 3 because it directly contacts the cable conductor. This material can quickly sense internal temperature changes and indicate overheating risks through a color change (e.g., from blue to red). Observation window 9 is a transparent or translucent area that allows direct observation of the color changes of inner layer 3 from outer layer 5, enabling non-destructive temperature monitoring.

[0041] In one embodiment, the highly weather-resistant and flame-retardant cable insulation protective shell further includes a protective copper shell 10 disposed within the outer sheath 2 .

[0042] In this embodiment, the protective copper shell 10, located within the highly weather-resistant and flame-retardant cable insulation shell, can resist external electromagnetic interference and maintain the stability of cable signal transmission. Furthermore, the strength of the metallic copper can withstand external extrusion or impact, extending the service life of the shell.

[0043] In one embodiment, the highly weather-resistant and flame-retardant cable insulation protective shell has a grounding terminal 11 on its outer sheath 2 , and the grounding terminal 11 is connected to the protective copper shell 10 .

[0044] In this embodiment, the protective copper shell 10 is connected to the grounding system via the grounding terminal 11 to discharge static electricity or lightning current to prevent equipment damage. This also meets the mandatory requirements for cable grounding in electrical safety standards.

[0045] In one embodiment, the highly weather-resistant and flame-retardant cable insulation protective shell has a wall thickness of 50 μm where the honeycomb holes 7 connect to the outer layer 5 , and a wall thickness of 200 μm where the honeycomb holes 7 connect to the inner layer 3 .

[0046] In this embodiment, gradient mechanical design is used to achieve a thin outer layer of honeycomb cells 7 and a thick inner layer. The 50 μm thin wall reduces weight and accommodates bending, while the 200 μm thick wall enhances load-bearing capacity and prevents structural deformation caused by internal pressure or thermal expansion.

[0047] The specific embodiments described above further illustrate the purpose of the present invention, technical solutions, and beneficial effects. It should be understood that the above description is merely a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. In particular, it should be noted that for those skilled in the art, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Highly weather-resistant and flame-retardant cable insulation protective shell, characterized by: It comprises two outer protective layers connected to each other by a flange, wherein the matrix of the outer protective layer is a composite of silane-grafted EPDM and polyaryletherketone, and carbon quantum dots are uniformly dispersed and embedded in the polyaryletherketone of the matrix; The outer protective layer includes an inner layer, an intermediate layer, and an outer layer arranged in sequence from the inside to the outside, the inner surface of the inner layer is provided with a spiral groove, the intermediate layer is a honeycomb plate, and the wall thickness of each honeycomb hole gradually increases from the outer layer to the inner layer, the honeycomb wall of each honeycomb hole is wavy, and a phase change material containing zinc borate, phosphorus nitrogen, and kaolin is poured into each honeycomb hole, and the phase change material melts to absorb heat when the temperature reaches a first set value, the outer layer is a scale layer that shields the intermediate layer, and each scale is embedded with a shape memory alloy wire, and the shape memory alloy wire shrinks to close the scale when the temperature reaches a second set value, and the second set value is less than the first set value. When the temperature of the phase change material reaches the first set value, each scale of the outer layer has contraction potential energy, and the closure of each scale causes the zinc borate, phosphorus nitrogen, and kaolin to seep outward along with the melt; Among them, zinc borate decomposes at high temperature to form boron oxide glass phase, which reacts with carbides contained in the matrix to form a ceramic layer. Phosphorus and nitrogen decompose at high temperature to form phosphoric acid, which reacts with aluminum hydroxyl contained in kaolin to form a carbon layer.

2. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: The carbon quantum dots account for 0.5% of the total mass of the composite.

3. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: The phase change material is a composite material of paraffin wax and expanded graphite.

4. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: An aerogel heat insulation layer is provided at the trough of the honeycomb wall.

5. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: The mass ratio of the zinc borate to the kaolin is 3:

1.

6. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: The shape memory alloy wire is made of nickel-titanium alloy.

7. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: The inner layer is provided with a thermochromic temperature-indicating material, and corresponding positions of the middle layer and the outer layer are provided with observation windows.

8. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: It also includes a protective copper shell arranged in the outer protective layer.

9. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 8, characterized in that: A grounding terminal is provided on the outer protective layer, and the grounding terminal is connected to the protective copper shell.

10. The highly weather-resistant and flame-retardant cable insulation protective cover according to claim 1, characterized in that: The thickness of the wall of the honeycomb holes connecting the outer layer is 50 μm, and the thickness of the wall of the honeycomb holes connecting the inner layer is 200 μm.

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