Acid and alkali resistant waterproof power cable

Abstract

The invention relates to the field of power cables, and particularly discloses an acid and alkali resistant waterproof power cable. The acid and alkali resistant waterproof power cable comprises a conductor layer, an insulating layer and a sheath layer which are sequentially arranged from inside to outside, the preparation method comprises the following steps: S1, preparing the conductor layer: smelting electrolytic copper, tin, silver and rare earth elements, and then performing wire drawing, and controlling the wire drawing speed to be 10-15m / s to obtain a conductor wire core; s2, extrusion of an insulating layer: mixing fluororubber, epichlorohydrin rubber, nano-silica and a flame retardant, and extruding the mixture at 70-90 DEG C by a twin-screw extruder to coat the conductor layer; s3, extruding a sheath layer: mixing the raw materials, and coating the raw materials outside the insulating layer at 60-85 DEG C by a single screw extruder; s4, irradiation crosslinking: carrying out electron beam irradiation on the coated cable; and S5, cooling and rolling. The cable can be used in a highly corrosive environment, and has the advantage of avoiding premature failure of the sheath layer of the power cable in the highly corrosive environment.

Description

Technical Field

[0001] The present application relates to the field of power cables, and more specifically, to an acid-resistant, alkali-resistant and waterproof power cable. Background Art

[0002] Power cable is an electrical device specially designed for the transmission and distribution of electrical energy. Its core structure consists of a conductor, an insulating layer that wraps the conductor, and a protective sheath and outer sheath. Unlike overhead wires, power cables are usually laid underground, on the seabed, in pipelines or inside buildings. They are used to connect power stations, substations, urban power grids, and supply power to various industrial and civilian power terminals. They are safe, reliable, have little environmental impact, and have high space utilization. They are suitable for power transmission systems of various voltage levels from low voltage to ultra-high voltage.

[0003] Related power cables usually use rubber-based composite materials as the basic protective layer, and improve the mechanical strength by adding carbon black, and meet the basic protection requirements under normal conditions. However, conventional single fillers cannot form a continuous barrier network in the matrix, resulting in the protective layer being accelerated by ultraviolet degradation due to acid corrosion in a composite corrosion environment, and photoaging exacerbates the expansion of microcracks to form penetration channels, leading to premature failure of the protective layer. Summary of the Invention

[0004] In order to solve the problem that the protective layer of related power cables usually adopts rubber-based composite materials as the basic protective layer, which causes premature failure of the protective layer in a composite corrosion environment, the present application provides an acid- and alkali-resistant and waterproof power cable.

[0005] The present application provides an acid- and alkali-resistant and waterproof power cable, which adopts the following technical solutions: An acid- and alkali-resistant and waterproof power cable comprises a conductor layer, an insulating layer, and a sheath layer, which are sequentially arranged from the inside out. The conductor layer is made of the following raw materials in parts by weight: 90-95 parts of electrolytic copper, 2-5 parts of tin, 0.5-1.5 parts of silver, and 0.1-0.8 parts of rare earth elements. The insulating layer is made of the following raw materials in parts by weight: 35-60 parts of fluororubber, 20-45 parts of epichlorohydrin rubber, 5-15 parts of nano-silicon dioxide, and 3-8 parts of a flame retardant. The sheath layer is made of the following raw materials in parts by weight: 50-80 parts of hydrogenated nitrile butadiene rubber, 0.3-1 part of carboxylated modified graphene, 10-25 parts of carbon black, and 1-4 parts of an antioxidant.

[0006] By adopting the above technical solution, the grain boundaries are pinned and the grains are refined by using a specific ratio of lanthanum-cerium alloy rare earth elements in the conductor layer, and the fluororubber / chloroether rubber synergistically compounded with the nano-silica three-dimensional network in the insulation layer enhances the corrosion resistance and flame retardancy of the power cable, and the carboxyl modified graphene in the sheath layer is directionally arranged to form a layered barrier. Therefore, the premature failure of the sheath layer of the power cable in a strong corrosive environment is avoided.

[0007] Preferably, the weight ratio of fluororubber to epichlorohydrin rubber in the insulating layer is 1.2-1.8:1.

[0008] By adopting the above technical solution, due to the use of a fluororubber to epichlorohydrin rubber weight ratio of 1.2-1.8:1 design, and a plasticizing process of 65±5℃ double-roller mixing for 30 minutes, followed by calendering to control the insulation layer thickness to 0.5mm, the power cable obtained has high insulation performance, and the tensile strength retention rate after aging at 120℃ reaches 92%, which meets the long-term insulation stability and mechanical durability requirements of high-voltage cables.

[0009] Preferably, the rare earth element of the conductor layer is one or more combinations of lanthanum, cerium and yttrium, and the particle size of the rare earth element is 1-5 μm.

[0010] By adopting the above technical solution, lanthanum / cerium / yttrium rare earth micropowders with a particle size of 1-5 μm are melted and incorporated, and a vacuum melting and rapid cold rolling process at 1550±20℃ is used in this process to form a rare earth solid solution grain boundary uniform distribution structure. Therefore, the obtained conductor layer has a stable high-temperature conductivity of ≥5.8×10 7 S / m, the thermal expansion coefficient is reduced to 8.2×10 -6 / K and formed into a strip with a thickness of 0.5 mm.

[0011] Preferably, the surface carboxylation degree of the carboxyl modified graphene of the sheath layer is 0.8-1.2 mmol / g, and the specific surface area is 150-250 m 2 / g.

[0012] By adopting the above technical solution, due to the surface carboxylation degree of 0.8-1.2mmol / g and the specific surface area of ​​150-250m 2 / g of carboxylated modified graphene was prepared, and the carboxylated modified graphene was treated by an aqueous phase treatment process of 800W ultrasonic dispersion for 30min and 12000rpm centrifugation for 10min, followed by an interface bonding strengthening process of 60℃ vacuum drying and curing. Therefore, the conductivity of the sheath layer was improved, the interface bonding strength was increased, and the uniformity of graphene dispersion was enhanced.

[0013] Preferably, it further comprises a water-blocking tape provided between the insulating layer and the sheath layer, wherein the water-blocking tape is made of a composite of super absorbent fiber and polyester non-woven fabric.

[0014] By adopting the above technical solution, due to the use of a composite structure of super absorbent fiber and polyester non-woven fabric, the two are processed by a lamination process with a hot pressing temperature of 130-150°C, a pressure of 0.8-1.2 MPa, and a composite speed of 2-3 m / min, and the fiber distribution is controlled by a loading amount of 35-45wt%, thereby achieving efficient waterproofing and mechanical reliability effects in the gap between the insulation layer and the sheath layer.

[0015] Preferably, the sheath layer further comprises 0.5-2 parts by weight of an ultraviolet absorber, and the ultraviolet absorber is a benzotriazole compound.

[0016] By adopting the above technical solution, since 0.5-2 parts of benzotriazole ultraviolet absorbers are used and the ultraviolet absorbers are melt-dispersed by a synchronous melt blending process with the sheath layer substrate through a mixing device, the sheath layer is prompted to form a stable ultraviolet shielding layer and the weather resistance is improved.

[0017] The present application provides a method for preparing an acid- and alkali-resistant and waterproof power cable, which adopts the following technical solution: A method for preparing an acid- and alkali-resistant and waterproof power cable comprises the following steps: S1: Conductor layer preparation: Electrolytic copper, tin, silver and rare earth elements are smelted and then drawn at a speed of 10-15 m / s to obtain a conductor core; S2: Insulation layer extrusion: Fluororubber, epichlorohydrin rubber, nano-silica and flame retardant are mixed and extruded through a twin-screw extruder at 70-90°C to coat the conductor layer; S3: Sheath layer extrusion: After mixing hydrogenated nitrile rubber, carboxyl modified graphene, carbon black and antioxidant, it is coated on the outside of the insulation layer through a single screw extruder at 60-85℃; S4: Irradiation cross-linking: The coated cable is subjected to electron beam irradiation with an irradiation dose of 15-30 kGy; S5: Cooling and rewinding: The cable is water-cooled to 25-40°C before rewinding.

[0018] Preferably, the head pressure of the twin-screw extruder in S2 is 8-12 MPa, and the screw aspect ratio is 28:1.

[0019] By adopting the above technical solution, 0.5-1 parts of lanthanum, cerium and rare earth with a particle size of 2-5 μm are mixed into the conductor layer, and the conductor layer raw materials are melted at 1100-1200 ° C and drawn at a speed of 10-15 m / s. In the insulation layer, 35-60 parts of fluororubber / 20-45 parts of chloroether rubber are compounded and extruded by a twin-screw extruder at 70-85 ° C., 0.3-1 parts of carboxylated modified graphene are used in the sheath layer in conjunction with carbon black and kneaded at 140-150 ° C., and then extruded through a single-screw extruder at 60-85 ° C., and then the cable is cross-linked by two-stage irradiation in the range of 15-30 kGy, and then the cable is water-cooled in steps. Therefore, the conductor layer, insulation layer and sheath layer with different properties cooperate with each other.

[0020] Preferably, 0.5-2 parts by weight of an ultraviolet absorber is further added to S3, and the mixture is dispersed at a speed of 600-800 rpm for 10-15 minutes during the mixing stage.

[0021] By adopting the above technical solution, due to the operation of limiting the head pressure to 8-12MPa and selecting a screw with a length-to-diameter ratio of 28:1, a synergistic effect of enhanced material compression and plasticization effect, improved component mixing and dispersion, and stable melt uniformity and physical properties is achieved.

[0022] Preferably, the electron beam irradiation of S4 is carried out in two stages, with a dose of 8-12 kGy in the first stage and a dose of 7-18 kGy in the second stage, with a cooling time of 2-5 minutes.

[0023] By adopting the above technical solution, due to the use of two-stage irradiation and ventilation cooling between the two stages of irradiation, and the use of a free radical recombination three-dimensional network construction mechanism, the cross-linking density is increased and the molecular chain breakage is avoided.

[0024] In summary, this application has the following beneficial effects: 1. Since the present application adopts the technical solution of adding modified graphene and ultraviolet absorber to the sheath layer, the layered barrier structure of the carboxylated modified graphene and the benzotriazole ultraviolet absorber synergistically inhibit acid corrosion and ultraviolet degradation, which makes the power cable zero cracking after the 10wt% H2SO4 immersion test, the water immersion local discharge is reduced, and the strength retention rate is high after the ultraviolet aging test, thereby achieving the effect of avoiding premature failure of the sheath layer of the power cable in a strong corrosive environment.

[0025] 2. In this application, the technical solution of adding rare earth elements to the conductor layer is preferably adopted. Since rare earth elements refine the grains and form solid solutions through the grain boundary pinning effect, the conductivity of the conductive layer is improved and the insulation resistance retention rate after the salt spray test is improved, thereby preventing the conductor from being easily oxidized in a high humidity environment and causing an increase in resistance.

[0026] 3. The method of the present application adopts a technical solution that optimizes the weight ratio of fluororubber to epichlorohydrin rubber in the insulating layer to 1.2-1.8:1. This ratio range enables the chemical resistance of fluororubber and the flexibility of epichlorohydrin rubber to produce a synergistic effect, thereby promoting the improvement of the volume resistivity and oxygen index of the insulating layer, thereby ensuring that the power cable has both high acid and alkali resistance and mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present application provides a process flow chart of a method for preparing an acid-resistant, alkali-resistant and waterproof power cable. DETAILED DESCRIPTION

[0028] The present application is further described in detail below with reference to the accompanying drawings and examples.

[0029] Related power cables usually use rubber-based composite materials as the basic protective layer, and improve the mechanical strength by adding carbon black, and meet the basic protection requirements under normal conditions. However, conventional single fillers cannot form a continuous barrier network in the matrix, resulting in the protective layer being accelerated by ultraviolet degradation due to acid corrosion in a composite corrosion environment, and photoaging exacerbates the expansion of microcracks to form penetration channels, leading to premature failure of the protective layer.

[0030] The present application provides an acid- and alkali-resistant and waterproof power cable, comprising a conductor layer, an insulating layer, and a sheath layer, which are arranged in sequence from the inside to the outside; the conductor layer is made of the following raw materials in parts by weight: 90-95 parts of electrolytic copper, 2-5 parts of tin, 0.5-1.5 parts of silver, and 0.1-0.8 parts of rare earth elements; the insulating layer is made of the following raw materials in parts by weight: 35-60 parts of fluororubber, 20-45 parts of epichlorohydrin rubber, 5-15 parts of nano-silicon dioxide, and 3-8 parts of a flame retardant; the sheath layer is made of the following raw materials in parts by weight: 50-80 parts of hydrogenated nitrile rubber, 0.3-1 part of carboxylated modified graphene, 10-25 parts of carbon black, and 1-4 parts of an antioxidant.

[0031] By adopting the technical solution of adding 0.3-1 parts of modified graphene and 0.5-2 parts of UV absorber to the sheath layer, the layered barrier structure of the carboxylated modified graphene and the benzotriazole UV absorber synergistically inhibit acid corrosion and UV degradation. This ensures that the power cable has zero cracking after 240 hours of immersion in 10wt% H2SO4, a local discharge of ≤2.5pC under water immersion, and a strength retention rate of ≥94% after 500 hours of UV aging, thereby solving the problem of premature failure of the protective layer.

[0032] An embodiment of the present application provides an acid- and alkali-resistant and waterproof power cable, comprising a conductor layer, an insulating layer, and a sheath layer, which are arranged in sequence from the inside to the outside; the conductor layer is made of the following raw materials in parts by weight: 90-95 parts of electrolytic copper, 2-5 parts of tin, 0.5-1.5 parts of silver, and 0.1-0.8 parts of rare earth elements; the insulating layer is made of the following raw materials in parts by weight: 35-60 parts of fluororubber, 20-45 parts of epichlorohydrin rubber, 5-15 parts of nano-silicon dioxide, and 3-8 parts of flame retardant; the sheath layer is made of the following raw materials in parts by weight: 50-80 parts of hydrogenated nitrile rubber, 0.3-1 part of carboxylated modified graphene, 10-25 parts of carbon black, and 1-4 parts of antioxidant.

[0033] Specifically, 90-95 parts of electrolytic copper, 2-5 parts of tin, 0.5-1.5 parts of silver and 0.1-0.8 parts of rare earth elements composed of a lanthanum-cerium alloy with a mass ratio of 3:1 are used as raw materials; the electrolytic copper is placed in a vacuum melting furnace and heated to 1120°C for complete melting, and then tin and silver are added and stirred for 25 minutes to achieve melting homogenization, and finally rare earth elements are added and stirred at 200 rpm for 10 minutes under argon protection, and a copper alloy conductor core wire with a diameter of 2.5 mm is formed by continuous casting and rolling. In this process, rare earth elements pin the grain boundaries by forming intermetallic compounds, so that the grain size is refined to 8.5 μm and the conductivity is increased to 102% IACS; 35-60 parts of fluororubber, 20-45 parts of chloroether rubber, a particle size of 20 nm and surface treated with silane coupling agent KH-570 are used for the preparation of the insulating layer. The invention discloses a method for preparing a rubber sheath comprising: premixing fluororubber and chloroether rubber in an internal mixer at 65°C for 5 minutes, adding nanosilica in three times and controlling the mixing temperature not to exceed 75°C, adding the flame retardant 3 minutes before the end of mixing, and the total mixing time is 18 minutes. Through this process, silica forms a dense three-dimensional network structure in the rubber matrix, with an oxygen index of 32.5 and improved acid permeability. The sheath layer uses 50-80 parts of hydrogenated nitrile rubber, 0.3-1 parts of graphene modified by acrylic acid grafting, 10-25 parts of N550 carbon black and 1-4 parts of antioxidant RD. The carboxyl modified graphene is pre-dispersed in the rubber base liquid by ball milling to form a premix, which is melt-blended with carbon black and antioxidant at 135°C in a twin-screw extruder, and the shear rate is controlled at 1500s. -1The graphene is arranged in a direction along the extrusion direction to form a continuous layered barrier structure; finally, a three-layer co-extrusion process is used to simultaneously cover the insulation layer and the sheath layer outside the conductor layer, the extrusion pressure is 12MPa, and the temperature gradient of the cooling water tank is reduced from 85°C to 25°C; experimental verification shows that the cable has a volume expansion rate of ≤1.8% after being immersed in 50wt% sodium hydroxide solution for 168 hours, while the same cable does not crack after being immersed in 10wt% sulfuric acid solution for 240 hours, and the local discharge under 10kV water immersion is stable at below 3pC, thereby achieving the effect of reducing the acid and alkali penetration rate of the graphene-modified sheath layer to 17% of that of conventional cables, and the insulation resistance retention rate is ≥95% after 3000 hours of salt spray test.

[0034] The weight ratio of fluororubber to chloroether rubber in the insulating layer is 1.2-1.8:1.

[0035] Specifically, fluororubber and epichlorohydrin rubber were weighed in a weight ratio of (1.2-1.8):1, the raw materials were placed in a two-roll mill, and mixed at 65±5°C for 30 minutes to fully plasticize the rubber and mix evenly. After calendering, an insulation layer sample with a thickness of 0.5 mm was obtained. Experimental testing showed that the volume resistivity of the obtained finished products was greater than 1.5×1015 Ω·cm, indicating that this ratio range can ensure that the insulation performance meets the application requirements of high-voltage cables, and the tensile strength retention rate of the finished products with a ratio of 1.2-1.8:1 reached 92% after aging test at 120°C.

[0036] The rare earth element of the conductor layer is one or more combinations of lanthanum, cerium and yttrium, and the particle size of the rare earth element is 1-5 μm.

[0037] Specifically, during the preparation of the conductor layer, rare earth element powder is added to optimize performance. The rare earth element is selected from a single component or a composite of lanthanum, cerium, and yttrium in any proportion. Its physical form is micron-sized particles processed by a ball milling process. The laser particle size analyzer is used for calibration and verification to ensure that the particle size of the rare earth powder is controlled within the range of 1μm-5μm. The rare earth powder is added by directly incorporating it into the conductor layer substrate during the melting stage, and the addition amount is 0.1wt%-1.5wt% of the total mass of the substrate. X-ray diffraction analysis of the conductor layer treated in this way shows that the rare earth elements are uniformly distributed at the grain boundaries in the form of a solid solution. This distribution feature enables the conductor layer to maintain a stable conductivity of 5.8×10 7 S / m, while the thermal expansion coefficient is reduced to 8.2×10 -6 / K, the implementation of this technical solution adopts conventional vacuum induction melting equipment, the melting temperature is controlled at 1550±20℃, the holding time is 30min, and finally the strip with a thickness of 0.5mm is formed by rapid cold rolling.

[0038] The carboxylation degree of the carboxyl modified graphene surface of the sheath layer is 0.8-1.2mmol / g, and the specific surface area is 150-250m 2 / g.

[0039] Specifically, the surface carboxylation degree of the carboxyl modified graphene raw material is 0.8-1.2 mmol / g as determined by acid-base titration, and the specific surface area is 150-250 m 2 / g; when preparing the sheath layer, the carboxyl-modified graphene is dispersed in deionized water, and after ultrasonic treatment at a power of 800W for 30 minutes, the upper suspension is centrifuged at 12000rpm for 10 minutes, and the upper suspension is evenly coated on the surface of the sheath layer substrate, and then vacuum dried and solidified at 60°C; performance testing has verified that the addition of carboxyl-modified graphene raw materials improves the conductivity of the sheath layer and the interfacial bonding strength. At the same time, this parameter combination can optimize the dispersion and interfacial bonding strength of graphene in the matrix.

[0040] It also includes a water-blocking tape arranged between the insulating layer and the sheath layer, and the water-blocking tape is made of a composite of super absorbent fiber and polyester non-woven fabric.

[0041] Specifically, a water-blocking tape is provided between the insulation layer and the sheath layer of the power cable. The water-blocking tape is made of super absorbent fiber and polyester non-woven fabric through a lamination process. The super absorbent fiber is made of cross-linked sodium polyacrylate-based material with a fiber diameter range of 15-25 μm and a water absorption rate of ≥150 g / g; and the polyester non-woven fabric base material has a gram weight of 40-60 g / m 2 , thickness 0.15-0.25mm; the parameters of the lamination process are set as: hot pressing temperature 130-150℃, pressure 0.8-1.2MPa, composite speed 2-3m / min; finally, the super absorbent fiber is evenly loaded in the gaps between the polyester non-woven fabric fibers, with a load of 35-45wt%, the thickness of the water-blocking tape is controlled at 0.48-0.52mm, and the longitudinal tensile strength is ≥18MPa.

[0042] The sheath layer further comprises 0.5-2 parts by weight of an ultraviolet absorber, which is a benzotriazole compound.

[0043] Specifically, when preparing the cable sheath layer, a benzotriazole ultraviolet absorber is mixed into the base material of the sheath layer in an amount of 0.5-2 parts. The ultraviolet absorber is evenly blended with the main material of the sheath layer through a mixing device to improve the weather resistance of the sheath layer under outdoor lighting conditions. The selection of benzotriazole compounds includes but is not limited to 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole and other derivatives, which are synchronously melted and dispersed with the polymer matrix during the mixing stage to finally form a sheath layer composite material with stable ultraviolet shielding function.

[0044] See attached Figure 1 A method for preparing an acid- and alkali-resistant and waterproof power cable comprises the following steps: S1: Conductor layer preparation: Electrolytic copper, tin, silver and rare earth elements are smelted and then drawn at a speed of 10-15 m / s to obtain a conductor core; S2: Insulation layer extrusion: Fluororubber, epichlorohydrin rubber, nano-silica and flame retardant are mixed and extruded through a twin-screw extruder at 70-90°C to coat the conductor layer; S3: Sheath layer extrusion: After mixing hydrogenated nitrile rubber, carboxyl modified graphene, carbon black and antioxidant, it is coated on the outside of the insulation layer through a single screw extruder at 60-85℃; S4: Irradiation cross-linking: The coated cable is subjected to electron beam irradiation with an irradiation dose of 15-30 kGy; S5: Cooling and rewinding: The cable is water-cooled to 25-40°C before rewinding.

[0045] Specifically, in S1, 90-95 parts of electrolytic copper, 3-5 parts of tin, 0.5-1.5 parts of silver and 0.5-1 part of lanthanum-cerium mixed rare earth with a particle size of 2-5 μm are placed in a vacuum induction furnace, the melting temperature is controlled to 1100-1200 ° C, and after melting under the protection of inert gas, a continuous casting unit is formed into a casting billet, which is drawn at a speed of 10-15 m / s to obtain a conductor core with a diameter of 2.5-3.0 mm; in S2, a twin-screw extruder is used. The barrel temperature is divided into 70-80℃ for the feeding section, 80-90℃ for the melting section and 75-85℃ for the die section. 35-60 parts of fluororubber, 20-45 parts of chloroether rubber, 5-15 parts of nano-silicon dioxide and 3-8 parts of ammonium polyphosphate flame retardant are pre-mixed and then added. The extrusion pressure is maintained at 8-12MPa. An insulation layer with a thickness of 1.0-1.5mm is formed on the outside of the conductor core. A single-screw extruder is used in S3 to mix 50-80 parts of hydrogenated nitrile rubber and 10-20 parts of nitrile rubber. 1 part, 0.3-1 part of carboxyl modified graphene, 10-25 parts of carbon black N330 and 1.0-4.0 parts of antioxidant 4010NA are mixed in an internal mixer at 140-150℃ for 10-20min, and then coated on the outside of the insulation layer at an extrusion temperature of 60-85℃ through a 50-80 mesh filter. The thickness of the sheath layer is controlled at 1.2-1.8mm. An electron accelerator device is used in S4, and the beam energy is set to 2.0-3.0MeV. The total dose of 15-30kGy is irradiated in two stages. After the first irradiation of 8-12kGy, the cable is air-cooled for 2-5 minutes, and then a second irradiation of 7-18kGy is implemented. In S5, the cable passes through three stepped water cooling tanks in sequence. The temperature of the first tank is 35±1℃, the second tank is 30±1℃ and the third tank is 25±1℃. The residence time of each tank is 30-60s. The cooling rate is controlled at ≤5℃ / min, and finally it is wound at a speed of 400-600m / h.

[0046] See attached Figure 1 , the head pressure of the twin-screw extruder in S2 is 8-12MPa, and the screw length-diameter ratio is 28:1.

[0047] Specifically, in S2, the head pressure control value is set to 8-12MPa. This pressure range can ensure that the material obtains compression and plasticization effects during the extrusion process, promoting the mixing and dispersion of various components. At the same time, the extruder's screw structure has an aspect ratio of 28:1. This aspect ratio can extend the residence time of the material in the barrel and enhance the shearing and mixing effects, ensuring the uniformity and physical properties of the melt.

[0048] See attached Figure 1 0.5-2 parts by weight of ultraviolet absorber are also added to S3, and the mixture is dispersed at a speed of 600-800 rpm for 10-15 minutes during the mixing stage.

[0049] Specifically, in S3, when the material temperature reaches 160℃±5℃, 0.5-2.0 parts of benzotriazole ultraviolet absorber are added to the internal mixer, and the mixture is added in two equal batches through the side feeding port, with an interval of 2.0 minutes between each batch; when the mixing speed is lower than 600rpm, the torque monitoring shows uneven dispersion, and when the mixing speed exceeds 800rpm, the melt temperature rises by more than 15℃ / min, triggering thermal oxidation side reactions, so the mixing speed is controlled within the range of 600rpm-800rpm; after continuous dispersion for 10.0min-15.0min, near-infrared spectroscopy is used to confirm that the characteristic peak intensity fluctuation value of the absorber is less than ±3%, which indicates that S3 achieves molecular-level dispersion; the phenolic hydroxyl group of the ultraviolet absorber forms a keto structure after absorbing ultraviolet photons, converts light energy into heat energy and releases it, and then restores its original configuration; this process needs to ensure the compatibility of the absorber with the polymer interface, so the melt shear rate is controlled at 5000s -1 -7000s -1 , the corresponding rotation speed range is 600-800rpm, and the dispersed phase particle size is ≤200nm; thermodynamic analysis shows that when the dosage of UV absorber is less than 0.5 parts, the transmittance is higher than 10%, which indicates that the critical concentration of UV absorption is insufficient; and when the dosage of UV absorber is higher than 2.0 parts, the crystallinity changes and causes the impact strength of the sheath layer to decrease, so the addition range of UV absorber is 0.5-2 parts.

[0050] See attached Figure 1 , S4 electron beam irradiation is carried out in two stages, the first stage dose is 8-12 kGy, the second stage dose is 7-18 kGy, and the interval cooling time is 2-5 minutes.

[0051] Specifically, in the first stage of irradiation, the cable passed through the first irradiation chamber at a transmission speed of 3.0m / min. The internal parameters of the first irradiation chamber were set as follows: beam energy of 2.5MeV, scanning width of 300mm, and electron beam irradiation dose of 8-12kGy. At the same time, the electron beam irradiation dose was calibrated in real time by a dosimeter and controlled in an environment 30°C below the glass transition temperature of the substrate material to ensure the initiation of free radical cross-linking reactions of the polymer molecular chains. Interval cooling: After the first stage of irradiation, the cables enter an air cooling tunnel. The parameters of the air cooling tunnel are set as follows: the forced ventilation temperature is set to 20±2℃, the wind speed is 5m / s, and the cooling is continued for 2-5 minutes. The cable surface temperature change is monitored in real time until it drops to 50℃. This operation is to prevent heat accumulation from causing molecular chain breakage. Second stage irradiation: After interval cooling, the cables enter the second irradiation chamber, the beam density is increased to 15mA, and the received dose is 17-18kGy; this stage promotes the recombination of free radicals to form a three-dimensional network structure, and the cross-linking density is increased to 75% as measured by the swelling method.

[0052] Example 1 The present embodiment provides an acid- and alkali-resistant and waterproof power cable, comprising a conductor layer, an insulating layer, and a sheath layer. The conductor layer is composed of the following components in parts by mass: 90 parts of electrolytic copper, 2 parts of tin, 0.5 parts of silver, and 0.1 parts of lanthanum-cerium alloy; the insulating layer is composed of the following components in parts by mass: 35 parts of fluororubber, 20 parts of chloroether rubber, 5 parts of nano-silicon dioxide, and 3 parts of ammonium polyphosphate flame retardant; the sheath layer is composed of the following components in parts by mass: 50 parts of hydrogenated nitrile rubber, 0.3 parts of carboxylated modified graphene, 10 parts of carbon black N550, and 1 part of antioxidant RD; the water-blocking tape is composed of a super absorbent fiber loading of 35 wt%, a polyester non-woven fabric weighing 40 g / m 2 ; Ultraviolet absorber: 0.5 parts of benzotriazole.

[0053] Preparation process of the above acid- and alkali-resistant and waterproof power cable: S1: Preparation of conductor layer: 90 parts of electrolytic copper were placed in a vacuum induction furnace, heated to 1100°C for melting, followed by adding 2 parts of tin and 0.5 parts of silver and stirring for 25 minutes. Subsequently, 0.1 parts of lanthanum-cerium alloy were added and stirred at 200 rpm for 10 minutes under argon protection. At this time, the molten raw material was drawn at 10 m / s. After continuous casting and rolling, the raw material obtained a conductor core with a diameter of 2.5 mm.

[0054] S2: Insulation layer extrusion: 35 parts of fluororubber and 20 parts of epichlorohydrin rubber were mixed at 65°C for 5 minutes; 5 parts of nanosilica were added in three batches at a temperature below 75°C; 3 parts of flame retardant were added 3 minutes before the end of mixing, and the total mixing time was 18 minutes. The mixed product was then coated on the outside of the conductor core through a twin-screw extruder to form an insulation layer. During this process, the barrel temperature was set in different zones, with the feeding section at 70°C, the melting section at 80°C, and the die head at 75°C. The extrusion pressure of the mixed product was set at 8MPa. S3: Sheath layer extrusion: 50 parts of hydrogenated nitrile rubber, 0.3 parts of carboxylated modified graphene, 10 parts of carbon black, and 1 part of antioxidant were kneaded at 140°C for 10 minutes. 0.5 parts of ultraviolet absorber were then added and dispersed at 600 rpm for 10 minutes. The melted product was extruded through a single-screw extruder at 60°C to coat the insulation layer. The sheath layer thickness was controlled to 1.2 mm. S4: Irradiation cross-linking: In the first stage, the cable passes through the first irradiation chamber at a speed of 3.0m / min. The electron beam energy of the electron accelerator in the first irradiation chamber is set to 2.5MeV, and the electron beam irradiation dose is 8kGy. The cable is then cooled in an air cooling tunnel for 2 minutes, reducing the cable surface temperature to 50°C. In the second stage, the cooled cable enters the second irradiation chamber, where the beam current density is increased to 15mA and the electron beam irradiation dose is adjusted to 17kGy. S5: Cooling and rewinding: The cable passes through three-stage water cooling tanks in sequence. The water temperature of the first stage is 35±1℃, the second stage is 30±1℃ and the third stage is 25±1℃. The residence time of each stage is 30s. The cooling rate is controlled at 3℃ / min and finally it is reeled at a speed of 400m / h.

[0055] Example 2 The present embodiment provides an acid- and alkali-resistant and waterproof power cable, comprising a conductor layer, an insulating layer, and a sheath layer. The conductor layer is composed of the following components in parts by mass: 92.5 parts of electrolytic copper, 3.5 parts of tin, 1.0 part of silver, and 0.45 part of lanthanum-cerium alloy; the insulating layer is composed of the following components in parts by mass: 47.5 parts of fluororubber, 32.5 parts of chloroether rubber, 10 parts of nano-silicon dioxide, and 5.5 parts of flame retardant; the sheath layer is composed of the following components in parts by mass: 65 parts of hydrogenated nitrile rubber, 0.65 parts of carboxylated modified graphene, 17.5 parts of carbon black, and 2.5 parts of antioxidant; the water-blocking tape is composed of a super absorbent fiber loading of 40 wt%, a polyester non-woven fabric weighing 50 g / m 2 ; Ultraviolet absorber: 1.25 parts of benzotriazole.

[0056] Preparation process of the above acid- and alkali-resistant and waterproof power cable: S1: Conductor layer preparation: 92.5 parts of electrolytic copper were placed in a vacuum induction furnace and heated to 1150°C to melt. Subsequently, 3.5 parts of tin and 1.0 part of silver were added and stirred at this temperature for 25 minutes. Subsequently, 0.45 parts of lanthanum-cerium alloy was added and stirred at 200 rpm under argon protection for 10 minutes. At this time, the molten raw material was drawn at 12.5 m / s. After continuous casting and rolling, the raw material obtained a conductor core with a diameter of 2.75 mm. S2: Insulation layer extrusion: 47.5 parts of fluororubber and 32.5 parts of epichlorohydrin rubber were mixed at 65°C for 5 minutes; 10 parts of nanosilica were added in three batches at a temperature below 75°C; 5.5 parts of flame retardant were added 3 minutes before the end of mixing, and the total mixing time was 18 minutes. The mixed product was then coated on the outside of the conductor core through a twin-screw extruder to form an insulation layer. During this process, the barrel temperature was set in different zones, with the feeding section at 75°C, the melting section at 85°C, and the die head at 80°C. The extrusion pressure of the mixed product was set at 10 MPa. S3: Sheath layer extrusion: 65 parts of hydrogenated nitrile rubber, 0.65 parts of carboxylated modified graphene, 17.5 parts of carbon black, and 2.5 parts of antioxidant were mixed at 145°C for 10 minutes. 1.25 parts of ultraviolet absorber were then added and dispersed at 700 rpm for 12.5 minutes. The melted product was then extruded onto the insulation layer using a single-screw extruder at 72.5°C. The sheath layer thickness was controlled to 1.5 mm. S4: Irradiation cross-linking: In the first stage, the cable passes through the first irradiation chamber at a speed of 3.0m / min. The electron beam energy of the electron accelerator in the first irradiation chamber is set to 2.5MeV, and the electron beam irradiation dose is 10kGy. The cable is then cooled in an air cooling tunnel for 3.5 minutes, reducing the cable surface temperature to 50°C. In the second stage, the cooled cable enters the second irradiation chamber, where the beam current density is increased to 15mA and the electron beam irradiation dose is adjusted to 12.5kGy. S5: Cooling and rewinding: The cable passes through three-stage water cooling tanks in sequence. The water temperature of the first stage is 35±1℃, the second stage is 30±1℃ and the third stage is 25±1℃. The residence time of each stage is 45s. The cooling rate is controlled at 3℃ / min and finally reeled at a speed of 500m / h.

[0057] Example 3 This embodiment provides an acid- and alkali-resistant and waterproof power cable, comprising a conductor layer, an insulating layer, and a sheath layer. The conductor layer is composed of the following components in parts by mass: 95 parts of electrolytic copper, 5 parts of tin, 1.5 parts of silver, and 0.8 parts of lanthanum-cerium alloy; the insulating layer is composed of the following components in parts by mass: 60 parts of fluororubber, 45 parts of chloroether rubber, 15 parts of nano-silicon dioxide, and 8 parts of flame retardant; the sheath layer is composed of the following components in parts by mass: 80 parts of hydrogenated nitrile rubber, 1.0 part of carboxylated modified graphene (carboxylated 1.2 mmol / g), 25 parts of carbon black, and 4 parts of antioxidant; the water-blocking tape is composed of 45 wt% of super absorbent fiber and 60 g / m2 of polyester non-woven fabric. 2 ; Ultraviolet absorber: 2.0 parts of benzotriazole.

[0058] Preparation process of the above acid- and alkali-resistant and waterproof power cable: S1: Conductor layer preparation: 95 parts of electrolytic copper were placed in a vacuum induction furnace and heated to 1200°C to melt. Subsequently, 5 parts of tin and 1.5 parts of silver were added and stirred at this temperature for 25 minutes. Subsequently, 0.8 parts of lanthanum-cerium alloy was added and stirred at 200 rpm under argon protection for 10 minutes. At this time, the molten raw material was drawn at 15 m / s. After continuous casting and rolling, the raw material obtained a conductor core with a diameter of 3.0 mm. S2: Insulation layer extrusion: 60 parts of fluororubber and 45 parts of epichlorohydrin rubber were mixed at 65°C for 5 minutes; 15 parts of nanosilica were added in three batches at a temperature below 75°C; 8 parts of flame retardant were added 3 minutes before the end of mixing, and the total mixing time was 18 minutes. The mixed product was then coated on the outside of the conductor core through a twin-screw extruder to form an insulation layer. During this process, the barrel temperature was set in different zones, with the feeding section at 80°C, the melting section at 90°C, and the die head at 85°C. The extrusion pressure of the mixed product was set at 12 MPa. S3: Sheath layer extrusion: 80 parts of hydrogenated nitrile rubber, 1.0 part of carboxylated modified graphene, 25 parts of carbon black, and 4 parts of antioxidant were mixed at 150°C for 10 minutes. 2.0 parts of ultraviolet absorber were then added and dispersed at 800 rpm for 15 minutes. The melted product was then extruded onto the insulation layer using a single-screw extruder at 85°C. The thickness of the sheath layer was controlled to be 1.8 mm. S4: Irradiation cross-linking: In the first stage, the cable passes through the first irradiation chamber at a speed of 3.0m / min. The electron beam energy of the electron accelerator in the first irradiation chamber is set to 2.5MeV, and the electron beam irradiation dose is 12kGy. The cable is then cooled in an air cooling tunnel for 5 minutes, reducing the cable surface temperature to 50°C. In the second stage, the cooled cable enters the second irradiation chamber, where the beam current density is increased to 15mA and the electron beam irradiation dose is adjusted to 18kGy. S5: Cooling and rewinding: The cable passes through three-stage water cooling tanks in sequence. The water temperature of the first stage is 35±1℃, the second stage is 30±1℃ and the third stage is 25±1℃. The residence time of each stage is 60s. The cooling rate is controlled at 3℃ / min and finally reeled at a speed of 600m / h.

[0059] Comparative Example 1 This comparative example provides a power cable, comprising a conductor layer, an insulation layer and a sheath layer, wherein rare earth elements are omitted from the conductor layer, and the remaining components are the same as those in Example 1.

[0060] Preparation process of the above power cable: No rare earth element is added to S1, and the rest is the same as in Example 1.

[0061] Comparative Example 2 This comparative example provides a power cable, comprising a conductor layer, an insulation layer and a sheath layer, wherein the insulation layer comprises fluororubber and epichlorohydrin rubber in a ratio of 1:1, i.e., 32.5 parts fluororubber and 32.5 parts epichlorohydrin rubber, and the remaining components are the same as those in Example 2.

[0062] Preparation process of the above power cable: The same as in Example 2.

[0063] Comparative Example 3 This comparative example provides a power cable, comprising a conductor layer, an insulation layer and a sheath layer, wherein the sheath layer deletes the carboxyl-modified graphene, and the remaining components are the same as those in Example 3.

[0064] Preparation process of the above power cable: Same as Example 3.

[0065] Conductor conductivity test: Method: Conductivity of conductor cores was measured using a four-probe resistance meter in accordance with GB / T3048. Samples were taken from the conductor layers of Examples 1-3 and Comparative Example 1. The surfaces were cleaned with alcohol before testing. Calculation: Conductivity (%IACS) = (standard copper conductivity / sample resistivity) × 100%. The standard copper conductivity was 58.0 MS / m.

[0066] Sample source: Three sections of 50 cm in length were taken from the conductor cores of Examples 1, 2, 3 and Comparative Example 1, and the results were averaged.

[0067] Insulation layer volume resistivity test: Method: According to IEC60243, the volume resistivity of the insulation layer was measured using a high resistance meter. The sample was a slice with an insulation layer thickness of 1.0 mm. A 500 V DC voltage was applied for 60 seconds. The volume resistivity (Ω·cm) was calculated as follows: (test voltage × sample thickness) / (current × sample area).

[0068] Sample source: 5 samples were prepared from the insulation layer materials of Examples 1, 2, 3 and Comparative Example 2.

[0069] Acid and alkali resistance test: method: Volume expansion rate after NaOH immersion: A 20 cm long cable sample was immersed in a 50 wt% NaOH solution for 168 hours. The volume change was measured after removal. The volume expansion rate (%) was calculated as follows: (volume after immersion - initial volume) / initial volume × 100%.

[0070] Observation of cracks after immersion in H2SO4: The samples were immersed in 10 wt% H2SO4 solution for 240 h. The surface cracks were observed using an optical microscope (magnification 100×), and the crack area ratio was calculated using image analysis software.

[0071] Sample source: 3 sections of each of the complete cables of Examples 1, 2, 3 and Comparative Example 3 were taken.

[0072] Waterproof test: Method: According to the IEC60502 standard, the cable sample was immersed in a water tank with a depth of 1m and an AC voltage of 10kV was applied. The partial discharge was then measured using a partial discharge detector. The test time was 30 minutes and the result was taken as the stable value.

[0073] Sample source: 2 samples with a length of 10 m were taken from each of the cables of Examples 1, 2, 3 and Comparative Example 3.

[0074] Salt spray test insulation resistance retention rate: Method: According to ASTM B117, the samples were placed in a salt spray chamber for 3000 hours. The salt spray chamber parameters were set to: 5wt% NaCl solution, pH 6.5-7.2, temperature 35°C. Before the test and every 500 hours during the test, the insulation resistance was measured with a megohmmeter. The calculation method is: Retention rate (%) = (resistance after test / initial resistance) × 100%.

[0075] Sample source: 3 sections of each of the cables of Examples 1, 2, 3 and Comparative Example 1 were taken.

[0076] UV aging intensity test: Method: According to GB / T16422.3 standard, the sheath layer sample was aged for 500 hours using a QUV accelerated aging instrument, in which the accelerated aging instrument has a built-in UVB-313 lamp with an irradiance of 0.71W / m 2 , measure the tensile strength after aging and calculate the retention rate: retention rate (%) = (strength after aging / initial strength) × 100%.

[0077] Sample source: 5 specimens (size 150 mm×25 mm) were prepared from the sheath layer materials of Examples 2, 3 and Comparative Example 3.

[0078] Irradiation crosslink density test: Method: Using the swelling method, the sample was immersed in toluene at a constant temperature of 25°C for 24 hours, and the mass before and after swelling was measured. The cross-linking density (%) was calculated as follows: (mass before swelling - mass after swelling) / mass before swelling × 100%.

[0079] Sample source: 3 portions of each of the irradiated sheath layer materials of Examples 1, 2, and 3 were taken.

[0080] Oxygen index test: Method: According to GB / T2406 standard, use an oxygen index meter to measure the minimum oxygen concentration required for the insulation material to maintain combustion in a nitrogen-oxygen mixture, and record the oxygen index (%).

[0081] Sample source: 5 samples were prepared from the insulation layer materials of Example 2 and Comparative Example 2.

[0082] Table 1:

[0083] Table 2:

[0084] Table 3:

[0085] Combining Example 1 and Comparative Example 1 with Table 1, it can be seen that the conductivity of the conductor layer with 0.1 parts of rare earth elements added reaches 101% IACS, and the cable insulation resistance retention rate after the salt spray test is 95%; while in Comparative Example 1, when there is no rare earth, the conductivity drops to 98% IACS, and the retention rate after salt spray treatment is 82%. This confirms that the rare earth elements refine the grains to 8.5 μm through the grain boundary pinning effect, thereby improving the conductivity and salt spray corrosion resistance, and avoiding the problem of easy oxidation of the conductor in a high humidity environment of the power cable, which leads to increased resistance. Combining Example 2 and Comparative Example 2 with Table 2, it can be seen that when the ratio of fluororubber to chloroether rubber is 1.46:1, the volume resistivity reaches 1.6×10 15 Ω·cm, and the oxygen index is 32.5%; while in comparative example 2, when the ratio is 1:1, the resistivity is reduced to 9.2×10 14 Ω·cm, and the oxygen index is 28%; this indicates that within the ratio range of 1.2-1.8:1, the high chemical resistance of fluororubber and the flexibility of epichlorohydrin rubber work synergistically to simultaneously improve the insulation performance and flame retardancy of the cable; In combination with Example 3 and Comparative Example 3 and Table 3, it can be seen that the sheath layer to which 1 part of carboxylated modified graphene is added has no cracks after immersion in 10wt% H2SO4, and the cable water immersion local discharge is 2.5pC, and the ultraviolet aging strength retention rate is 94%; while in Comparative Example 3 without graphene, the crack area reaches 15%, and the cable water immersion local discharge is 28pC, and the ultraviolet aging retention rate is 70%; it is confirmed that the carboxylated modified graphene improves the acid resistance through the layered barrier structure to achieve no cracking, maintains the integrity of the cable outer layer, and thereby improves the waterproofness of the cable. At the same time, the carboxylated modified graphene and the benzotriazole ultraviolet absorber synergistically enhance the weather resistance of the cable, avoiding early failure of the sheath layer in a strong corrosive environment.

[0086] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An acid and alkali resistant and waterproof power cable, characterized in that: It includes a conductor layer, an insulating layer and a sheath layer arranged in sequence from the inside to the outside; The conductor layer is made of the following raw materials in parts by weight: 90-95 parts of electrolytic copper, 2-5 parts of tin, 0.5-1.5 parts of silver and 0.1-0.8 parts of rare earth elements; The insulating layer is made of the following raw materials in parts by weight: 35-60 parts of fluororubber, 20-45 parts of epichlorohydrin rubber, 5-15 parts of nano-silicon dioxide and 3-8 parts of flame retardant; The sheath layer is made of the following raw materials in parts by weight: 50-80 parts of hydrogenated nitrile rubber, 0.3-1 part of carboxyl modified graphene, 10-25 parts of carbon black and 1-4 parts of antioxidant.

2. The acid- and alkali-resistant and waterproof power cable according to claim 1, characterized in that: The weight ratio of fluororubber to epichlorohydrin rubber in the insulating layer is 1.2-1.8:

1.

3. The acid- and alkali-resistant and waterproof power cable according to claim 1, characterized in that: The rare earth element of the conductor layer is one or more combinations of lanthanum, cerium and yttrium, and the particle size of the rare earth element is 1-5 μm.

4. The acid- and alkali-resistant and waterproof power cable according to claim 1, characterized in that: The carboxyl modified graphene surface of the sheath layer has a carboxyl degree of 0.8-1.2 mmol / g and a specific surface area of ​​150-250 m 2 / g.

5. The acid- and alkali-resistant and waterproof power cable according to claim 1, characterized in that: It also includes a water-blocking tape arranged between the insulating layer and the sheath layer, and the water-blocking tape is made of a composite of super absorbent fiber and polyester non-woven fabric.

6. The acid- and alkali-resistant and waterproof power cable according to claim 1, characterized in that: The sheath layer further comprises 0.5-2 parts by weight of an ultraviolet absorber, which is a benzotriazole compound.

7. A method for preparing an acid- and alkali-resistant waterproof power cable, used for the acid- and alkali-resistant waterproof power cable according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Conductor layer preparation: Electrolytic copper, tin, silver and rare earth elements are smelted and then drawn at a speed of 10-15 m / s to obtain a conductor core; S2: Insulation layer extrusion: Fluororubber, epichlorohydrin rubber, nano-silica and flame retardant are mixed and extruded through a twin-screw extruder at 70-90°C to coat the conductor layer; S3: Sheath layer extrusion: After mixing hydrogenated nitrile rubber, carboxyl modified graphene, carbon black and antioxidant, it is coated on the outside of the insulation layer through a single screw extruder at 60-85℃; S4: Irradiation cross-linking: The coated cable is subjected to electron beam irradiation with an irradiation dose of 15-30 kGy; S5: Cooling and rewinding: The cable is water-cooled to 25-40°C before rewinding.

8. The method for preparing an acid- and alkali-resistant and waterproof power cable according to claim 7, characterized in that: The head pressure of the twin-screw extruder in S2 is 8-12 MPa, and the screw length-diameter ratio is 28:

1.

9. The method for preparing an acid- and alkali-resistant and waterproof power cable according to claim 7, characterized in that: 0.5-2 parts by weight of ultraviolet absorber is also added to S3, and the mixture is dispersed at a speed of 600-800 rpm for 10-15 minutes during the mixing stage.

10. The method for preparing an acid- and alkali-resistant and waterproof power cable according to claim 7, characterized in that: Electron beam irradiation of S4 is carried out in two stages, with a dose of 8-12 kGy in the first stage and 7-18 kGy in the second stage, with a cooling time of 2-5 minutes.

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