Cable with cable insulation layer and preparation method thereof

Abstract

The invention relates to the technical field of power cables, and particularly discloses a cable with a cable insulation layer and a preparation method thereof, and the cable comprises a conductor and an insulation layer wrapping the conductor. The preparation method comprises the following steps: S1, raw material pretreatment: preheating and softening the high-strength silicone rubber in a temperature interval of 120-150 DEG C; s2, a mixing procedure: adding an aluminum hydroxide flame retardant and ethylene-vinyl acetate copolymer resin into the pretreated high-strength silicone rubber; and S3, extruding and coating: applying the mixed composite material to the periphery of a conductor through an extruder, and controlling the extrusion temperature to be 140-170 DEG C. The cable can be used for power transmission in a high-temperature environment, and has the advantages that the flexibility and tear resistance are maintained in the high-temperature environment, and meanwhile, the long-term thermal stability is improved; in addition, the preparation method disclosed by the invention has the advantages of improving the compatibility of the filler and the matrix and improving the mechanical property of the cable.

Description

Technical Field

[0001] This application relates to the field of power cable technology, and more specifically, to a cable with a cable insulation layer and a method for preparing the same. Background Technology

[0002] Power cables are cables used to transmit and distribute electrical energy. They are usually composed of one or more mutually insulated conductors, with insulation layers, shielding layers, sheaths, and other structures covering the conductors. They can reliably transmit electrical energy in power systems and have the characteristics of good insulation performance, large transmission capacity, and immunity to external environmental influences. They are widely used in power transmission in urban power grids, industrial enterprises, buildings, and other fields.

[0003] The relevant power cables form a protective layer with polyethylene and polyvinyl chloride. The main molecular chains and carbon-carbon bonds of polyethylene and polyvinyl chloride are the main structure. When the operating temperature exceeds 70°C, the carbon-carbon bonds are easily oxidized and broken by heat, the molecular chains degrade, and the tensile strength of the insulation layer decreases by more than 35% after long-term high-temperature aging, which leads to a decrease in the thermal stability of the cable. Summary of the Invention

[0004] In order to solve the problem of reduced thermal stability caused by the use of polyethylene and polyvinyl chloride as protective layers in related power cables, this application provides a cable with a cable insulation layer and a method for preparing the same.

[0005] In a first aspect, this application provides a cable with a cable insulation layer, employing the following technical solution: A cable with cable insulation includes a conductor and an insulation layer covering the conductor, said insulation layer comprising the following components in parts by weight: 2-4 parts of high-strength silicone rubber; 4-6 parts of aluminum hydroxide flame retardant; 1-3 parts of ethylene-vinyl acetate copolymer resin.

[0006] By adopting the above technical solution, the use of high-strength silicone rubber as the matrix skeleton results in a silicon-oxygen bond in the molecular backbone that has a stronger inherent strength than the traditional carbon-carbon bond, giving the layer high dimensional stability and tear resistance under thermal load conditions. The aluminum hydroxide flame retardant undergoes a decomposition and endothermic phase transition in the temperature range of 230℃ to 350℃, and the concentration of combustible gas is diluted through the vaporization of crystal water, while simultaneously generating a continuous nano-alumina ceramic film in situ to prevent oxygen penetration. The ethylene-vinyl acetate copolymer resin, with the polar vinyl acetate units contained in its molecular chain, forms a hydrogen bond topological interpenetrating network with the silanol groups of silicone rubber, and utilizes its hot melt processing characteristics to optimize the dispersion continuity of inorganic fillers during mixing. Therefore, it achieves the elimination of micro-defects at the organic / inorganic interface, thereby synergistically enhancing the insulation layer's resistance to environmental stress-induced cracking and the durability of its flame retardant performance.

[0007] Preferably, the aluminum hydroxide flame retardant undergoes surface modification treatment, wherein the surface modification treatment involves coating the aluminum hydroxide particles with a titanate coupling agent.

[0008] By adopting the above technical solution, the aluminum hydroxide flame retardant undergoes hydrolytic condensation with the hydroxyl groups on the aluminum hydroxide surface after being coated with a titanate coupling agent, forming Al-O-Ti chemical bonds. The long-chain alkyl groups of the coupling agent are entangled with the organic matrix molecular chains through van der Waals forces. This modification process is completed at 80–100℃ and 800–1200 rpm for 20–40 min, thus achieving a 40% improvement in the dispersion uniformity of the flame retardant in the matrix, an interfacial bonding strength of 15 MPa, and optimized mechanical properties and thermal stability of the cable insulation layer.

[0009] Preferably, the aluminum hydroxide flame retardant is in the form of nano-sized particles with a D50 particle size distribution in the range of 30nm to 100nm.

[0010] By adopting the above technical solution, since the aluminum hydroxide flame retardant is prepared by wet grinding into nanoparticles, and using 0.3 mm zirconia beads to grind at 3000 rpm for 120 min, its specific surface area reaches 150–300 m². 2 / g, the thermal decomposition initiation temperature drops to 230℃ and the heat absorption reaches 1.55kJ / g, and the decomposition generates a nano-alumina barrier layer with an oxygen diffusion coefficient of <5×10 -12 m 2 The dense ceramic barrier, with a density of / s, is achieved through ultrasonic dispersion at 28kHz during mixing, resulting in agglomerate size <1μm and interfacial bonding strength increased to 18MPa. This results in a cable with a LOI >38% and a volume resistivity >1×10⁻⁶ at 150℃. 14 The effect of Ω·cm.

[0011] Secondly, this application provides a method for preparing a cable with a cable insulation layer, using the following technical solution: A method for preparing a cable with a cable insulation layer includes the following steps: S1: Raw material pretreatment: Preheat and soften the high-strength silicone rubber in the temperature range of 120℃~150℃; S2: Mixing process: Add aluminum hydroxide flame retardant and ethylene-vinyl acetate copolymer resin to the pretreated high-strength silicone rubber, and mix in an internal mixer at 130-160℃ and 0.6-1.2MPa for 15-30 minutes; S3: Extrusion Coating: The compounded composite material is applied to the outer periphery of the conductor through an extruder, with the extrusion temperature controlled at 140-170℃.

[0012] By adopting the above technical solutions, S1 preheats at 120–150℃ for 15 min, increasing the free volume of silicone rubber by 120% and reducing the Shore A hardness to 45±3, reaching a plastic state; S2 mixes 5 parts Al(OH)3 flame retardant and 2 parts EVA resin at 45 rpm, 145±5℃, and 0.9±0.3 MPa for 20 min; S3 coats the conductor through twin-screw extrusion, thus achieving the effects of enhanced interfacial bonding, improved dispersion uniformity, optimized mechanical strength, and precision molding.

[0013] Preferably, the aluminum hydroxide flame retardant used in S2 needs to undergo surface modification treatment beforehand. The treatment process includes: stirring aluminum hydroxide with a coupling agent accounting for 1.5% to 3% of its mass at 80 to 100°C at a speed of 800 to 1200 rpm for 20 to 40 minutes.

[0014] By adopting the above technical solution, the pretreatment of aluminum hydroxide flame retardant is carried out in a high-speed disperser: 2.0% titanate coupling agent is added uniformly at 85±5℃ and stirred at 1000±200rpm for 30min, so that the alkoxy groups of the coupling agent are hydrolyzed and condensed with the hydroxyl groups on the surface of Al(OH)3 to form a 1.8–2.2nm Al-O-Ti bonded layer, and its long-chain alkyl groups are pre-anchored to the polymer matrix by van der Waals forces; thus, the effect of SEM-EDS verification shows that the agglomerate size is reduced from 12.5μm to 3.8μm and the interfacial bonding strength is increased to 15.2MPa.

[0015] Preferably, during the mixing process of S2, an ultrasonic field with a frequency of 20 to 40 kHz is applied simultaneously, and the ultrasonic power density is 0.5 to 1.5 W / cm.

[0016] By adopting the above technical solution, by uniformly adding 2.0% titanate coupling agent at 85±5℃ and stirring at 1000±200rpm for 30min, the alkoxy groups of the coupling agent are hydrolyzed and condensed with the hydroxyl groups on the Al(OH)3 surface to form a 1.8–2.2nm Al-O-Ti chemical bond layer. At the same time, its long-chain alkyl groups are pre-anchored to the polymer matrix through van der Waals forces. Therefore, the SEM-EDS verified effect of reducing the agglomerate size from 12.5μm to 3.8μm and increasing the interfacial bonding strength to 15.2MPa is obtained.

[0017] Preferably, the rotor speed of the internal mixer is set to 30-60 rpm, and the mixing time of S2 is controlled to be 20 minutes.

[0018] By adopting the above technical solution, and by setting the internal mixer rotor speed to 45±15 rpm and mixing at a constant temperature of 145±5℃ for 20 minutes, this speed, based on the shear rate calculation formula, stabilizes the melt shear rate at 12-24 s. -1The range ensures that the shear force of 0.8-1.6N on the filler can overcome the van der Waals force of 0.5nN. At the same time, during the mixing process, the torque value evolves with time in three stages: the torque increases to 32kN·m during the initial 0-5min dry powder wetting period, the torque is maintained at 28±2kN·m during the middle 5-15min dispersion equilibrium period, and the torque decreases to 25kN·m during the later 15-20min molecular chain relaxation period. Therefore, the effect of obtaining nano-aluminum hydroxide agglomerate size ≤0.8μm and dispersion phase spacing variation coefficient ≤5% verified by SEM is achieved.

[0019] Preferably, the die pressure of the extruder in S3 is maintained at 8-15 MPa, and the conductor traction speed is controlled at 10-25 m / min.

[0020] By adopting the above technical solution, the melt shear rate is stabilized at 120-250 s by controlling the die pressure of the extrusion process to 12±3 MPa. -1 Meanwhile, the melt elastic modulus was reduced to 0.15 MPa, effectively avoiding sharkskin defects; and because the conductor traction speed was set to 18±7 m / min, matching the melt relaxation time τ=1.2s, the molecular chain orientation degree reached 85%, and the crystallinity was increased to 35±2% as verified by DSC; and the temperature gradient was set to 140±5℃ for the feeding section, 155±3℃ for the compression section, and 170±2℃ for the die section. Therefore, the crystal size reached 200-300nm after SAXS testing.

[0021] Preferably, the coupling agent is γ-aminopropyltriethoxysilane, and the amount used is 2% of the mass of aluminum hydroxide.

[0022] By adopting the above technical solution, γ-aminopropyltriethoxysilane is selected as the coupling agent, and its dosage is controlled at 2.0% of the mass of aluminum hydroxide. The silane is dissolved in a 4:1 ethanol-water mixed solvent to prepare a 5% mass fraction solution. The solution is then hydrolyzed at 90±2℃ and stirred at 1200rpm for 20min to generate silanol. After that, aluminum hydroxide powder is added and the treatment is continued for 30min. This allows the silanol to undergo a condensation reaction with the hydroxyl groups on the filler surface to form Al-O-Si covalent bonds. The amino groups provide hydrogen bonding sites with silicone rubber. Therefore, the coupling agent effectively modifies aluminum hydroxide, enhancing its bonding performance with silicone rubber.

[0023] Preferably, the ultrasonic frequency is fixed at 28kHz, and the ultrasonic power density is set to 1.0W / cm². 3 .

[0024] By adopting the above technical solution, the ultrasonic frequency is fixed at 28±0.5kHz, and the ultrasonic power density is set at 1.0±0.2W / cm². 3An ultrasonic probe was immersed in the melt to a depth of 50 mm and acted for 15 min, forming cavitation bubbles with diameters of 0.1-200 μm in the melt. When these bubbles collapsed, they generated extreme conditions of local temperature of 5000 K and pressure of 500 MPa, as well as a microjets of 100 m / s. This disrupted the 0.5 eV van der Waals forces between aluminum hydroxide particles. At the same time, the acoustic flow effect resulted in a Reynolds number Re > 4000, which increased the eddy current intensity of the melt by 40%. Therefore, the effect of reducing the agglomeration size of the nanofiller to 0.76 ± 0.13 μm and the coefficient of variation of distribution CV = 3.8%, as verified by SEM, was achieved.

[0025] In summary, this application has the following beneficial effects: 1. Because this application uses the molecular structure characteristic that the silicon-oxygen bond energy in the high-strength silicone rubber molecular chain is higher than that of the conventional carbon-carbon bond energy, the breaking of silicon-oxygen bonds in high-temperature environments requires the absorption of more energy, which improves the tensile strength retention rate of the cable insulation layer after long-term high-temperature aging, ensuring that the cable maintains its flexibility and tear resistance in high-temperature environments, while also improving long-term thermal stability.

[0026] 2. In this application, nano-alumina hydroxide is preferably used, which undergoes a decomposition reaction at 230 to 350 degrees Celsius. The heat absorption per unit mass is 1.55 kJ / g, which is higher than that of micron-sized fillers. Due to the formation of a dense alumina ceramic layer with a thickness of 0.5 microns, the oxygen diffusion coefficient is reduced, which blocks the contact between combustible gases and oxygen, resulting in highly efficient and lightweight flame retardancy and enhancing the stability and safety of the cable in harsh environments.

[0027] 3. The method of this application forms Al-O-Si covalent and hydrogen bonding sites on the surface of aluminum hydroxide by γ-aminopropyltriethoxysilane, thereby improving the strength of the filler-matrix interface and enabling the cable to maintain a high tensile strength retention rate after long-term high-temperature aging. Thus, it achieves the effect of improving the compatibility between the filler and the matrix and improving the mechanical properties of the cable. Attached Figure Description

[0028] Figure 1 This is a schematic cross-sectional view of a cable with cable insulation layer proposed in this application; Figure 2 This is a flowchart illustrating a method for preparing a cable with a cable insulation layer as proposed in this application.

[0029] Among them, 1. conductor; 2. insulating layer. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] The relevant power cables use polyethylene and polyvinyl chloride to form the insulation layer. The main molecular chains and carbon-carbon bonds of polyethylene and polyvinyl chloride are the main structure. When the operating temperature exceeds 70°C, the carbon-carbon bonds are easily oxidized and broken by heat, the molecular chains degrade, and the tensile strength of the insulation layer decreases by more than 35% after long-term high-temperature aging, which leads to a decrease in the thermal stability of the cable.

[0032] This application provides a cable with a cable insulation layer and a method for preparing the same. The cable with the cable insulation layer includes a conductor and an insulation layer covering the conductor. The insulation layer contains the following components in parts by weight: 2-4 parts of high-strength silicone rubber; 4-6 parts of aluminum hydroxide flame retardant; and 1-3 parts of ethylene-vinyl acetate copolymer resin.

[0033] The high-strength silicone rubber molecular chain used in the insulation layer has a higher silicon-oxygen bond energy than the conventional carbon-carbon bond energy. The breaking of silicon-oxygen bonds in high-temperature environments requires the absorption of more energy, which improves the tensile strength retention rate of the cable insulation layer after long-term high-temperature aging. This ensures that the cable maintains its flexibility and tear resistance in high-temperature environments, while also improving long-term thermal stability, thereby solving the problem of reduced thermal stability of power cables.

[0034] Please see the appendix Figure 1 This application provides a cable with a cable insulation layer, including a conductor 1 and an insulation layer 2 covering the conductor. The insulation layer 2 is composed of components comprising the following parts by mass: 2-4 parts of high-strength silicone rubber; 4-6 parts of aluminum hydroxide flame retardant; 1-3 parts of ethylene-vinyl acetate copolymer resin.

[0035] Specifically, in the two-component insulation layer, high-strength silicone rubber serves as the main matrix material. The silicon-oxygen bonds in its molecular chain have higher bond energies than conventional carbon-carbon bonds, giving the insulation layer excellent thermal stability and flexible tear resistance. The aluminum hydroxide flame retardant undergoes an endothermic phase transition upon thermal decomposition, releasing water of crystallization in the range of 230℃ to 350℃. This reduces the concentration of flammable gases through a gas-phase dilution effect, while simultaneously generating an alumina ceramic barrier layer that isolates oxygen. The molecular chain of the ethylene-vinyl acetate copolymer resin contains strongly polar vinyl acetate groups, which form a molecular-level entanglement network with the high-strength silicone rubber through hydrogen bonding. Furthermore, its thermoplastic properties promote the uniform dispersion of the aluminum hydroxide flame retardant during the mixing process, eliminating interfacial defects between the inorganic filler and the organic matrix. This synergistically enhances the insulation layer's resistance to environmental stress cracking and its flame-retardant durability.

[0036] See appendix Figure 1 The aluminum hydroxide flame retardant undergoes surface modification treatment, which involves coating the aluminum hydroxide particles with a titanate coupling agent.

[0037] Specifically, the surface modification treatment of aluminum hydroxide flame retardant involves coating the particles with a titanate coupling agent. The alkoxy groups in this coupling agent molecule undergo a hydrolytic condensation reaction with the hydroxyl groups on the surface of aluminum hydroxide, forming a stable aluminum-oxygen-titanium chemical bond interface. Simultaneously, the long-chain organic groups of the titanate coupling agent, namely C... 12 -C 18 Alkyl groups extend outwards and form molecular chain entanglements with the organic polymer matrix through van der Waals forces. This process is carried out in the temperature range of 80℃ to 100℃ and is continuously treated for 20 min to 40 min at a stirring rate of 800 rpm to 1200 rpm. The dispersion uniformity of the aluminum hydroxide flame retardant in the organic matrix is ​​improved by 40% after surface coating, and the interfacial bonding strength with the matrix reaches 15 MPa, thereby optimizing the mechanical properties and long-term thermal stability of the cable insulation layer.

[0038] See appendix Figure 1 The aluminum hydroxide flame retardant is made of nano-sized particles with a D50 particle size distribution in the range of 30nm to 100nm.

[0039] Specifically, the aluminum hydroxide flame retardant consists of nanoscale particles prepared by a wet milling process. The volumetric cumulative particle size distribution (D50) is controlled within the range of 30 nm to 100 nm. This size range is achieved by continuously processing the particles with 0.3 mm diameter zirconia grinding media at 3000 rpm for 120 minutes. The nanoparticles have a diameter of 150 nm. 2 / g~300m 2 With a specific surface area of ​​ / g, its thermal decomposition reaction initiation temperature is reduced to 230℃, and the heat absorption per unit mass reaches 1.55kJ / g, which is 40% higher than that of conventional micron-sized fillers; the nano-alumina barrier layer generated by decomposition is less than 0.5μm thick, forming a continuous and dense ceramic barrier, and the oxygen diffusion coefficient is reduced to 5×10 -12 m 2 / s or less; during the composite material mixing stage, a 28kHz ultrasonic field with a power density of 0.5W / cm² is used. 3 ~1.5W / cm 3 Assisted dispersion stabilizes particle agglomeration size to less than 1μm, increases interfacial bonding strength to 18MPa, and ultimately imparts a limiting oxygen index of over 38% and a volume resistivity of over 1×10⁻⁶ at 150℃ to the cable insulation layer. 14 Ω·cm.

[0040] See appendix Figure 2 A method for preparing a cable with a cable insulation layer includes the following steps: S1: Raw material pretreatment: Preheat and soften the high-strength silicone rubber in the temperature range of 120℃~150℃; S2: Mixing process: Add aluminum hydroxide flame retardant and ethylene-vinyl acetate copolymer resin to the pretreated high-strength silicone rubber, and mix in an internal mixer at 130-160℃ and 0.6-1.2MPa for 15-30 minutes; S3: Extrusion Coating: The compounded composite material is applied to the outer periphery of the conductor through an extruder, with the extrusion temperature controlled at 140-170℃.

[0041] Specifically, in S1, high-strength silicone rubber is placed in a hot air circulating oven and preheated for 15 minutes at a temperature range of 120℃~150℃, causing the free volume of the silicone rubber molecular chains to expand to 120% of their original volume, and the Shore A hardness to decrease to 45±3, reaching the plastic state requirement. In S2, the preheated silicone rubber is fed into an internal mixer, and 5 parts by weight of aluminum hydroxide flame retardant and 2 parts by weight of ethylene-vinyl acetate copolymer resin are added. The mixture is then kneaded under the conditions of a rotor speed of 45 rpm, a temperature of 145±5℃, and a pressure of 0.9±0.3 MPa. During the 20-minute process, the vinyl acetate groups of EVA resin and the silanol groups of silicone rubber form hydrogen bonds with an energy of 25 kJ / mol. At the same time, the mechanical shear force controls the agglomeration size of the filler to below 1.5 μm. In S3, the compound is coated with the conductor by a twin-screw extruder under temperature gradient control. The feed section is 140℃, the compression section is 155℃, and the die section is 170℃. The screw length-to-diameter ratio is 40:1, the die pressure is 12 MPa, and the traction speed is 18 m / min. This results in an insulation layer crystallinity of 35% and a thickness tolerance controlled within ±0.05 mm.

[0042] See appendix Figure 2 The aluminum hydroxide flame retardant used in S2 needs to undergo surface modification treatment beforehand. The treatment process includes stirring aluminum hydroxide with a coupling agent accounting for 1.5% to 3% of its mass at 80 to 100°C at a speed of 800 to 1200 rpm for 20 to 40 minutes.

[0043] Specifically, the pretreatment process of aluminum hydroxide flame retardant is implemented as follows: aluminum hydroxide powder is placed in a high-speed disperser, heated to 85±5℃, and 2.0% by mass of titanate coupling agent is added at a uniform speed. The chemical composition of titanate is isopropyltris(dioctylpyrophosphoryloxy) titanate. The mixture is stirred continuously at 1000±200 rpm for 30 min. During this process, the alkoxy groups of the coupling agent are hydrolyzed to generate hydroxyl groups, which undergo a condensation reaction with the hydroxyl groups on the surface of aluminum hydroxide to form an Al-O-Ti chemical bond layer with a thickness of 1.8-2.2 nm. At the same time, the long-chain alkyl groups of the coupling agent pre-anchor to the polymer matrix through van der Waals forces. The dispersion uniformity of the modified filler in the silicone rubber matrix is ​​verified by SEM-EDS. The agglomeration size is reduced from 12.5 μm to 3.8 μm, and the interfacial bonding strength is increased to 15.2 MPa.

[0044] See appendix Figure 2 During the mixing process of S2, an ultrasonic field with a frequency of 20 to 40 kHz is applied simultaneously, and the ultrasonic power density is 0.5 to 1.5 W / cm.

[0045] Specifically, an ultrasonic field of 20kHz to 40kHz is applied simultaneously during the mixing process, with the ultrasonic probe immersed in the melt to a depth of 50mm and the power density controlled at 0.8±0.3W / cm³. 3 The ultrasonic waves generated cavitation bubbles with diameters of 0.1-200 μm in the melt. Upon collapse, these bubbles formed microjets with a local temperature of 5000 K and a pressure of 500 MPa, with a velocity of 100 m / s. These microjets were able to disrupt the van der Waals forces between aluminum hydroxide particles. Simultaneously, the acoustic flow effect increased the eddy current intensity of the melt by 40%, promoting the uniformity of nanoparticle dispersion. SEM verification showed that the agglomeration size was reduced to below 0.8 μm, and the coefficient of variation (CV) of the filler distribution was <5%.

[0046] See appendix Figure 2 The rotor speed of the internal mixer is set to 30-60 rpm, and the mixing time of S2 is controlled to 20 minutes.

[0047] Specifically, the internal mixer rotor speed is set to 45±15 rpm, and the mixture is stirred for 20 minutes under a constant temperature of 145±5℃; this speed range is based on the shear rate calculation formula: Where R is the rotor radius and h is the gap, the melt shear rate is stabilized at 12-24 s. -1 Within a certain range, the shear force on the filler is 0.8-1.6N, which overcomes the van der Waals force of 0.5nN. The torque value during the mixing process evolves over time in three stages: initially, during the dry powder wetting period (0-5 min), the torque increases to 32kN·m; during the dispersion equilibrium period (5-15 min), it remains at 28±2kN·m; and during the molecular chain relaxation period (15-20 min), it decreases to 25kN·m. Finally, SEM verification shows that the agglomerate size of nano-aluminum hydroxide is ≤0.8μm, and the coefficient of variation (CV) of the dispersed phase spacing is ≤5%.

[0048] See appendix Figure 2 In S3, the die pressure of the extruder is maintained at 8-15 MPa, and the conductor traction speed is controlled at 10-25 m / min.

[0049] Specifically, the extrusion process parameters are set as follows: die pressure is controlled at 12±3MPa, and conductor traction speed is set at 18±7m / min; this pressure range stabilizes the melt shear rate at 120-250s. -1 The shear rate is based on the formula Where W is the die width, H is the height, and Q is the volumetric flow rate; at the same time, the melt elastic modulus is reduced to 0.15MPa to avoid sharkskin defects; the traction speed is matched with the melt relaxation time τ = 1.2s to achieve a molecular chain orientation degree of 85%, and DSC verification shows that the crystallinity is improved to 35±2%; the temperature gradient is controlled as follows: feed section 140±5℃, compression section 155±3℃, die section 170±2℃, and the crystal size reaches 200-300nm after SAXS testing.

[0050] See appendix Figure 2 The coupling agent used is γ-aminopropyltriethoxysilane, and the amount used is 2% of the mass of aluminum hydroxide.

[0051] Specifically, γ-aminopropyltriethoxysilane is selected as the coupling agent, and its dosage is controlled at 2.0% of the mass of aluminum hydroxide. Then, the silane is dissolved in an ethanol-water mixed solvent with a volume ratio of 4:1 to prepare a 5% mass fraction solution. The solution is then hydrolyzed at 90±2℃ and stirred at 1200 rpm for 20 min to generate silanol. Subsequently, aluminum hydroxide powder is added and the treatment is continued for 30 min, so that the silanol and the hydroxyl groups on the filler surface undergo a condensation reaction to form Al-O-Si covalent bonds, while the amino groups provide hydrogen bonding sites with the silicone rubber.

[0052] See appendix Figure 2 The ultrasonic frequency was fixed at 28kHz, and the ultrasonic power density was set to 1.0W / cm². 3 .

[0053] Specifically, the ultrasonic frequency is fixed at 28±0.5kHz, and the ultrasonic power density is set at 1.0±0.2W / cm². 3 The ultrasonic probe was immersed in the melt to a depth of 50 mm for 15 min, forming cavitation bubbles with a diameter of 0.1-200 μm in the melt. Upon collapse, these bubbles generated extreme conditions of local temperature 5000 K and pressure 500 MPa, with a microjet velocity of 100 m / s. This effectively disrupted the van der Waals forces between aluminum hydroxide particles by 0.5 eV. Simultaneously, the acoustic flow effect resulted in a Reynolds number Re > 4000, increasing the melt eddy current intensity by 40%. SEM verification showed that this reduced the agglomeration size of the nanofiller to 0.76 ± 0.13 μm, while the coefficient of variation (CV) was 3.8%.

[0054] Example 1 This embodiment provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor. The insulation layer is composed of components comprising the following parts by weight: High-strength silicone rubber: 2 parts; Aluminum hydroxide flame retardant: 4 parts; Ethylene-vinyl acetate copolymer resin: 1 part; The manufacturing process of the above-mentioned cable with cable insulation layer: S1: Preheat high-strength silicone rubber at 120℃ for 15 minutes, and the Shore A hardness will decrease to 48; S2: Add modified aluminum hydroxide flame retardant and EVA resin to the pretreated silicone rubber, and mix in a Banbury mixer at 145℃ / 0.9MPa / 45rpm for 20min, while simultaneously applying 28kHz / 1.0W / cm. 3 ultrasound; S3: Extrusion coating (feed section 140℃ / compression section 155℃ / die section 170℃), die pressure 12MPa, traction speed 18m / min.

[0055] Example 2 This embodiment provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor. The insulation layer is composed of components comprising the following parts by weight: High-strength silicone rubber: 3 parts; Aluminum hydroxide flame retardant: 5 parts (modified with titanate coupling agent, D50 = 65nm); Ethylene-vinyl acetate copolymer resin: 2 parts.

[0056] The manufacturing process of the above-mentioned cable with cable insulation layer: Same as Example 1.

[0057] Example 3 This embodiment provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor. The insulation layer is composed of components comprising the following parts by weight: High-strength silicone rubber: 4 parts; Aluminum hydroxide flame retardant: 6 parts; Ethylene-vinyl acetate copolymer resin: 3 parts.

[0058] The manufacturing process of the above-mentioned cable with cable insulation layer: Same as Example 1.

[0059] Example 4 This embodiment provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor. The insulation layer is composed of components comprising the following parts by weight: High-strength silicone rubber: 3 parts; Aluminum hydroxide flame retardant: 5 parts; Ethylene-vinyl acetate copolymer resin: 2 parts.

[0060] The manufacturing process of the above-mentioned cable with cable insulation layer: S1: Preheat high-strength silicone rubber at 120℃ for 15 minutes to soften it, and the Shore A hardness will be reduced to 48. S2: Add 5 parts aluminum hydroxide flame retardant and 2 parts EVA resin to the pretreated silicone rubber; mixing conditions: 130℃, 0.6MPa, mixing for 30min, with a rotor speed of 30rpm; S3: Extrusion coating temperature gradient: feeding section 140℃, compression section 140℃, die section 150℃; die pressure: 8MPa, traction speed: 10m / min.

[0061] Example 5 This embodiment provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor. The insulation layer is composed of components comprising the following parts by weight: Same as Example 4.

[0062] The manufacturing process of the above-mentioned cable with cable insulation layer: S1 raw material pretreatment: The high-strength silicone rubber is preheated and softened at 135℃ for 15 minutes to reduce its Shore A hardness to 45.

[0063] S2 mixing process: Add 5 parts aluminum hydroxide flame retardant and 2 parts ethylene-vinyl acetate copolymer resin to the pretreated silicone rubber. The mixture was mixed in an internal mixer at 145°C and 0.9 MPa for 22.5 minutes, with a rotor speed of 45 rpm.

[0064] S3 Extrusion Coating: The conductor is coated by an extruder. The extrusion temperature gradient is as follows: feed section: 155℃; compression section: 155℃; die section: 165℃; die pressure: 11.5MPa; traction speed: 17.5m / min.

[0065] Example 6 This embodiment provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor. The insulation layer is composed of components comprising the following parts by weight: Same as Example 4.

[0066] The manufacturing process of the above-mentioned cable with cable insulation layer: S1. Raw material pretreatment: Preheat and soften the high-strength silicone rubber at 150℃ for 15 minutes to reduce its Shore A hardness to 42; S2. Mixing process: Add 5 parts of aluminum hydroxide flame retardant and 2 parts of ethylene-vinyl acetate copolymer resin to the pretreated silicone rubber; mix in an internal mixer at 160℃ and 1.2MPa for 15 minutes, with the rotor speed at 60rpm.

[0067] S3. Extrusion Coating: The conductor is coated by an extruder. The extrusion temperature gradient is as follows: feed section: 160℃; compression section: 165℃; die section: 170℃; die pressure: 15MPa; traction speed: 25m / min.

[0068] Comparative Example 1 This comparative example provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor, the insulation layer being composed of components comprising the following parts by weight: Same as Example 1, but the aluminum hydroxide flame retardant was not modified.

[0069] The manufacturing process of the above-mentioned cable with cable insulation layer: S2: Cancel ultrasonic treatment, and change the mixing conditions to 160℃ / 0.6MPa / 30rpm for 30min; the remaining steps are the same as in Example 1.

[0070] Comparative Example 2 This comparative example provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor, the insulation layer being composed of components comprising the following parts by weight: Same as Example 2, but the aluminum hydroxide is micron-sized and unmodified.

[0071] The manufacturing process of the above-mentioned cable with cable insulation layer: The steps are the same as in Example 2.

[0072] Comparative Example 3 This comparative example provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor, the insulation layer being composed of components comprising the following parts by weight: Same as Example 3.

[0073] The manufacturing process of the above-mentioned cable with cable insulation layer: S2: Cancel ultrasonic treatment and extend the mixing time to 30 min; the remaining steps are the same as in Example 3.

[0074] Comparative Example 4 This comparative example provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor, the insulation layer being composed of components comprising the following parts by weight: Unmodified aluminum hydroxide was used, and the rest was the same as in Example 4.

[0075] The manufacturing process of the above-mentioned cable with cable insulation layer: S2: Surface modification and ultrasonication are omitted. Mix at 160°C and 0.6MPa for 30 minutes. The rest is the same as in Example 4.

[0076] Comparative Example 5 This comparative example provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor, the insulation layer being composed of components comprising the following parts by weight: Aluminum hydroxide was replaced with micron-sized aluminum hydroxide; otherwise, the process was the same as in Example 5.

[0077] The manufacturing process of the above-mentioned cable with cable insulation layer: Same as Example 5.

[0078] Comparative Example 6 This comparative example provides a cable with a cable insulation layer, including a conductor and an insulation layer covering the conductor, the insulation layer being composed of components comprising the following parts by weight: Same as Example 6.

[0079] The manufacturing process of the above-mentioned cable with cable insulation layer: S2 cancels ultrasound, otherwise the same as in Example 6.

[0080] Performance testing Detection method: Volume resistivity: Tested according to IEC62631-3-1 (150℃); Limiting Oxygen Index (LOI): Tested according to ASTM D2863; Dispersed particle size: Statistical based on ISO13322-1 SEM.

[0081] Performance Comparison Table 1: Test items Control group 1 Example 1 Testing standards in conclusion Volume resistivity <![CDATA[3.1×10 13 ]]> <![CDATA[8.5×10 13 ]]> IEC62631-3-1 Increased by 174% Performance Comparison Table 2: Test items Control group 2 Example 2 Testing standards in conclusion LOI 30.5％ 38.5％ ASTM D2863 An increase of 26.2%. Performance Comparison Table 3: Test items Control group 3 Example 3 Testing standards in conclusion Group size 3.9μm 0.81μm ISO 13322-1 79% reduction Performance Comparison Table 4: Performance Comparison Table 5: Test items Comparative Example 5 Example 5 Testing standards in conclusion Limiting oxygen index 30.5％ 38.5％ ASTM D2863 Nanofillers promote LOI improvement Performance Comparison Table 6: Example Conclusion: Combining Example 1 and Comparative Example 1 with the performance comparison table 1, it can be seen that after modification with the titanate coupling agent, the agglomerate size of Example 1 decreased to 0.85 μm, a reduction of 79.8%, and the volume resistivity increased to 8.5 × 10⁻⁶. 13 Ω·cm confirms that the Al-O-Ti bonding layer formed on the surface optimizes the interfacial bonding strength and insulation performance.

[0082] Combining Example 2 and Comparative Example 2 with the performance comparison table 2, it can be seen that in Example 2, the LOI increased to 38.5% after using nanoscale fillers, an increase of 26.2%, and the coefficient of variation decreased to 3.8%, verifying that the 30-100nm particle size range can pass through 250nm. 2 The high specific surface area enhances the endothermic effect of thermal decomposition, resulting in a qualitative change in flame retardant efficiency.

[0083] Combining Example 3 and Comparative Example 3 with Performance Comparison Table 3, it can be seen that Example 3 uses 28kHz / 1.0W / cm². 3 After ultrasound, the aggregate size stabilized at 0.81 μm, a decrease of 79%, and the binding strength increased to 18 MPa, an increase of 112%. This proves that the 500 MPa microjets generated by the ultrasonic cavitation effect can break the 0.5 eV van der Waals forces and achieve molecular-level dispersion strengthening.

[0084] Combining Example 4 and Comparative Example 4 with the performance comparison table 4, it can be seen that Comparative Example 4, which uses unmodified aluminum hydroxide, produces interface defects and causes a 64% decrease in resistivity, confirming that the titanate coupling agent coating can improve the interfacial bonding force.

[0085] Combining Example 5 and Comparative Example 5 with the performance comparison table 5, it can be seen that Comparative Example 5 uses micron-sized fillers and the LOI is 30.5% as tested, while Example 5 uses nano-sized fillers and the LOI reaches 38.5% as tested. This verifies that 30-100nm particle size improves flame retardant efficiency through high specific surface area.

[0086] Combining Example 6 and Comparative Example 6 with the performance comparison table 6, it can be seen that Comparative Example 6, which used no ultrasonic treatment, resulted in an aggregate size of 3.9 μm, while Example 5, which used 28 kHz / 1.0 W / cm², showed a smaller aggregate size. 3 Ultrasonic treatment reduced the aggregate size to 0.76 μm, demonstrating the effectiveness of ultrasonic treatment.

[0087] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A cable with cable insulation, comprising a conductor (1) and an insulation layer (2) covering the conductor, characterized in that, The insulating layer (2) comprises the following components in parts by weight: 2-4 parts of high-strength silicone rubber; 4-6 parts of aluminum hydroxide flame retardant; 1-3 parts of ethylene-vinyl acetate copolymer resin.

2. A cable with a cable insulation layer according to claim 1, characterized in that, The aluminum hydroxide flame retardant undergoes surface modification treatment, which involves coating the aluminum hydroxide particles with a titanate coupling agent.

3. A cable with a cable insulation layer according to claim 1, characterized in that, The aluminum hydroxide flame retardant is in the form of nano-sized particles with a D50 particle size distribution in the range of 30nm to 100nm.

4. A method for preparing a cable with a cable insulation layer, characterized in that, A cable with cable insulation layer as described in any one of claims 1-3, comprising the following steps: S1: Raw material pretreatment: Preheat and soften the high-strength silicone rubber in the temperature range of 120℃~150℃; S2: Mixing process: Add aluminum hydroxide flame retardant and ethylene-vinyl acetate copolymer resin to the pretreated high-strength silicone rubber, and mix in an internal mixer at 130~160℃ and 0.6~1.2MPa for 15~30 minutes; S3: Extrusion Coating: The compounded composite material is applied to the outer periphery of the conductor through an extruder, with the extrusion temperature controlled at 140-170℃.

5. The method for preparing a cable with a cable insulation layer according to claim 4, characterized in that, The aluminum hydroxide flame retardant used in S2 needs to undergo surface modification treatment beforehand. The treatment process includes stirring aluminum hydroxide with a coupling agent accounting for 1.5% to 3% of its mass at 80 to 100°C at a speed of 800 to 1200 rpm for 20 to 40 minutes.

6. The method for preparing a cable with a cable insulation layer according to claim 4, characterized in that, During the mixing process of S2, an ultrasonic field with a frequency of 20~40kHz is applied simultaneously, and the ultrasonic power density is 0.5~1.5W / cm.

7. The method for preparing a cable with a cable insulation layer according to claim 4, characterized in that, The rotor speed of the internal mixer is set to 30-60 revolutions per minute, and the mixing time of S2 is controlled to 20 minutes.

8. A method for preparing a cable with a cable insulation layer according to claim 4, characterized in that, In S3, the die pressure of the extruder is maintained at 8~15MPa, and the conductor traction speed is controlled at 10~25m / min.

9. A method for preparing a cable with a cable insulation layer according to claim 4, characterized in that, The coupling agent used is γ-aminopropyltriethoxysilane, and the amount used is 2% of the mass of aluminum hydroxide.

10. A method for preparing a cable with a cable insulation layer according to claim 4, characterized in that, The ultrasonic frequency was fixed at 28kHz, and the ultrasonic power density was set to 1.0W / cm³.

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