High-weather-resistant flame-retardant cable insulation protective shell

Abstract

The invention provides a high-weather-resistance flame-retardant cable insulation protection shell which comprises two outer protection layers connected with each other through a flange, a base body of each outer protection layer is a composite body of silane grafted EPDM and polyaryletherketone, and carbon quantum dots are embedded into the polyaryletherketone of the base body in a uniformly dispersed mode; the outer protection layer comprises an inner layer, a middle layer and an outer layer which are sequentially arranged from inside to outside, a spiral groove is formed in the inner surface of the inner layer, the middle layer is a honeycomb plate, the wall thickness of each honeycomb hole is gradually increased from the outer layer to the inner layer, the honeycomb wall of each honeycomb hole is in a wave shape, each honeycomb hole is filled with a phase-change material containing zinc borate, phosphorus nitrogen and kaolin, and the phase-change material is a phase-change material containing zinc borate, phosphorus nitrogen and kaolin. The phase-change material is melted to absorb heat when the temperature reaches a first set value, the outer layer is a scale layer for shielding the middle layer, a shape memory alloy wire is embedded in each scale, the shape memory alloy wires shrink to close the scales when the temperature reaches a second set value, and the second set value is smaller than the first set value. The zinc borate, the phosphorus nitrogen and the kaolin seep outwards 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] The cable insulation protective shell connects or segments the metal sheath of the high-voltage cable. The protective shell also provides electrical insulation, external sealing, ground connection and mechanical protection for the intermediate joint. In recent years, as power companies have increased their requirements for cable accessories, the flame retardant performance requirements for supporting products have also increased, prompting suppliers to optimize and upgrade the traditional copper shell insulation layer by using new composite materials to achieve a higher flame retardant grade.

[0003] However, there is still room for improvement in the weather resistance and flame retardancy of cable insulation protective shells. Because the traditional blending process leads to weak interfacial bonding between the flame retardant and the polymer matrix, microcracks are easily caused under the action of ultraviolet rays. In addition, the homogeneous structure produces isotropic expansion during temperature cycles, which easily leads to interfacial stratification. This is the main reason why weather resistance can be further improved. Because a single-component flame retardant system cannot achieve "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, that is, the flame heats the air to form an updraft, generating strong convection in the smooth channel, continuously inhaling fresh oxygen and exhausting high-temperature flue gas, resulting in a doubling of the 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-mentioned technical problems and provides 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 comprises 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 which are sequentially arranged 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, each honeycomb hole is infused with a phase change material containing zinc borate, phosphorus nitrogen, and kaolin, the phase change material melts to absorb heat when the temperature reaches a first set value, the outer layer is a scale layer shielding the intermediate layer, each scale is embedded with a shape memory alloy wire, the shape memory alloy wire shrinks when the temperature reaches a second set value to close the scale, the second set value is less than the first set value, the zinc borate, the phosphorus nitrogen, and the kaolin seep outward when the scale is closed;

[0007] Among them, zinc borate decomposes at high temperature to generate 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 generate 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 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 implementation manner, a grounding terminal is provided on the outer protective layer, and the grounding terminal is connected to the protective copper shell.

[0016] As an implementation manner, 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, so that the matrix of the outer sheath 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, can absorb ultraviolet light, and 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 polymer chains. Therefore, the weather resistance of the cable insulation protective shell is improved through material improvements.

[0018] In addition to the improvement in material, the matrix is ​​also improved in structure, that is, a layered structure of an inner layer, an intermediate layer, and an outer layer is set. The spiral groove set in the inner layer can guide the combustion gas to form a Coanda effect vortex and extend the flame path. The intermediate layer is a composite structure of a honeycomb plate and a corrugated plate, that is, the side walls of each honeycomb hole of the honeycomb plate are corrugated, so that each honeycomb hole can be filled with a phase change material containing zinc borate, phosphorus nitrogen, and kaolin. The phase change material melts when the temperature reaches a first set value. At this time, each scale of the outer layer has contraction potential energy, because the shape memory alloy wire shrinks 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 causes zinc borate, phosphorus nitrogen, and kaolin to seep out with the melt. Zinc borate and phosphorus nitrogen are both flame retardants. 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. The ceramic layer can isolate oxygen and reflect heat, terminating the combustion chain reaction. Phosphorus and nitrogen decompose at high temperatures to generate phosphoric acid, which reacts with 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 to achieve synergistic flame retardancy. It can be seen that the outer sheath, through the improvement of materials and structures, enables the inner layer, middle layer, and outer layer to respond to high temperatures together, achieving synchronous flame retardancy inside and outside. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0021] Figure 3 A schematic cross-sectional view of the inner layer of the outer sheath of a highly weather-resistant and flame-retardant cable insulation protective shell provided in 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 described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments 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 comprises two outer sheaths 2 connected to each other by a flange 1, wherein the matrix of the outer sheath 2 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 2 comprises an inner layer 3, an intermediate layer 4, and an outer layer 5 arranged in sequence from the inside to the outside, wherein the inner surface of the inner layer 3 is provided with a spiral groove 6, the intermediate layer 4 is a honeycomb plate, 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 generate 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 generate phosphoric acid, which reacts with aluminum hydroxyl contained in 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, can absorb ultraviolet light, and 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. As a result, the cable insulation protective shell improves weather resistance through material improvements.

[0027] In addition to the improvement in material, the matrix is ​​also improved in structure, that is, a layered structure of an inner layer 3, an intermediate layer 4, and an outer layer 5 is set. The spiral groove 6 set in the inner layer 3 can guide the combustion gas to form a Coanda effect vortex and extend the flame path. The spiral groove 6 is a groove arranged spirally along the axis of the outer protective layer 2. The intermediate layer 4 is a composite structure of a honeycomb plate and a corrugated plate, that is, the side walls of each honeycomb hole 7 of the honeycomb plate are wavy, so that each honeycomb hole 7 can be filled with a phase change material containing zinc borate, phosphorus nitrogen, and kaolin. The honeycomb plate is used because the honeycomb hole 7 of the honeycomb plate can provide light weight and high pressure resistance, which is conducive to the infusion of phase change materials containing zinc borate, phosphorus nitrogen, and kaolin. The wall thickness of each honeycomb hole 7 gradually increases from the outer layer 5 to the inner layer 3, forming a continuously changing thickness gradient. In this way, the thin-wall design of the outer layer 5 reduces the weight and adapts to the surface flexibility requirements, that is, the closed extrusion of the scale layer. The thick wall design of the inner layer 3 enhances the 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 the first set value. At this time, each scale 8 of the outer layer 5 already has contraction potential energy, because the shape memory alloy wire shrinks when the temperature reaches the second set value, and the second set value is less than the first set value. Therefore, the closure of the scale 8 causes zinc borate, phosphorus nitrogen, and kaolin to seep out with the melt. Zinc borate and phosphorus nitrogen are both flame retardants. 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. The ceramic layer can isolate oxygen and reflect heat, terminating the combustion chain reaction. Phosphorus nitrogen decomposes at high temperature to form phosphoric acid, which reacts with aluminum hydroxyl contained in kaolin to form a carbon layer, providing an incremental carbon layer required to form a ceramic layer, thereby strengthening the ceramic layer to synergistically retardant. It can be seen that the outer protective layer 2 improves the material and structure together, so that the inner layer 3, the middle layer 4, and the outer layer 5 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 of 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, the carbon quantum dots are set to 0.5wt%, which can protect 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. It can also avoid uneven dispersion and decreased mechanical properties 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 has the function of heat storage and temperature regulation. Specifically, paraffin wax absorbs heat through phase change from solid to liquid, which alleviates the high temperature accumulation during cable operation. Expanded graphite, as a porous carrier, wraps the paraffin wax to prevent leakage. It can also enhance the thermal conductivity of the composite material and promote uniform 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 trough of the corrugated structure is a weak point for stress concentration and heat transfer. Filling aerogel here can specifically block the external high temperature from being transmitted to the middle layer and the inner layer. At the same time, due to its extremely low density, aerogel avoids increasing the overall weight.

[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 to 3:1, 3 parts of zinc borate decompose at high temperature to generate a boron oxide glass layer to isolate oxygen, and 1 part of kaolin acts as a catalyst to promote carbonization and enhance the strength of the ceramic layer. After the ratio optimization of 3:1, it is ensured that the two react fully and avoid excessive kaolin causing material embrittlement.

[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 the shape memory effect at a specific temperature, the alloy wire contracts, driving the scales 8 of the scale layer to close, thereby actively enhancing the thermal insulation and sealing properties. Nickel-titanium alloy is fatigue-resistant and corrosion-resistant, and is 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 materials (such as cobalt salt complexes) are placed at a certain position of the inner layer 3 because the inner layer 3 directly contacts the cable conductor, and the thermochromic temperature-indicating materials can quickly sense internal temperature changes and indicate overheating risks through color changes (such as blue → red). The observation window 9 refers to a transparent or translucent area that allows the color change of the inner layer 3 to be directly observed from the outer layer 5, thereby realizing 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 disposed in the highly weather-resistant flame-retardant cable insulation protective shell can resist external electromagnetic interference and protect the stability of cable signal transmission. In addition, the material strength of the metal copper can resist external extrusion or impact and extend the service life of the protective 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 through the grounding terminal 11 to discharge static electricity or lightning current to prevent equipment damage, and 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 are connected to the outer layer 5 , and a wall thickness of 200 μm where the honeycomb holes 7 are connected to the inner layer 3 .

[0046] In this embodiment, the outer layer of the honeycomb hole 7 is thin-walled and the inner layer of the honeycomb hole 7 is thick-walled by gradient mechanical setting. The 50 μm thin wall can reduce weight and adapt to bending. The 200 μm thick wall can enhance the bearing capacity and prevent structural deformation caused by internal pressure or thermal expansion.

[0047] The specific implementation methods described above further describe the invention purpose, technical solutions, and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the protection scope of the present invention. It is particularly pointed out 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 protection scope of the present invention.

Claims

1. Highly weather-resistant and flame-retardant cable insulation protective shell, characterized in that: It comprises two outer protective layers connected to each other by flanges, 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 which are sequentially arranged 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, each honeycomb hole is infused with a phase change material containing zinc borate, phosphorus nitrogen, and kaolin, the phase change material melts to absorb heat when the temperature reaches a first set value, the outer layer is a scale layer shielding the intermediate layer, each scale is embedded with a shape memory alloy wire, the shape memory alloy wire shrinks when the temperature reaches a second set value to close the scale, the second set value is less than the first set value, the zinc borate, the phosphorus nitrogen, and the kaolin seep outward when the scale is closed; Among them, zinc borate decomposes at high temperature to generate 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 generate 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 shell according to claim 1 is 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 shell according to claim 1, characterized in that: The phase change material is a composite material of paraffin and expanded graphite.

4. The highly weather-resistant and flame-retardant cable insulation protective shell 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 shell 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 shell 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 shell according to claim 1, characterized in that: The inner layer is provided with a thermochromic temperature indicating material, and the 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 shell 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 shell according to claim 8, characterized in that: The outer protective layer is provided with a grounding terminal, and the grounding terminal is connected to the protective copper shell.

10. The highly weather-resistant and flame-retardant cable insulation protective shell according to claim 1, characterized in that: 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.

Images