Corrosion-resistant insulated power cable

Abstract

The invention relates to the technical field of cables, and provides a corrosion-resistant insulated power cable. The corrosion-resistant insulated power cable is sequentially provided with a conductor layer, an insulating layer and a sheath layer from inside to outside, and the insulating layer is prepared from the following raw materials in parts by weight: low-density polyethylene, magnesium hydroxide and calcium carbonate composite powder, an antioxidant, dicumyl peroxide, zinc stearate and polyethylene wax; the sheath layer comprises the following raw materials in parts by weight: PVC resin, magnesium hydroxide and calcium carbonate composite powder, diisononyl phthalate, a calcium-zinc composite stabilizer, an antioxidant, polyethylene wax and calcium stearate. According to the corrosion-resistant insulated power cable prepared in the invention, the corrosion resistance of the power cable in extreme corrosion environments such as strong acid, strong alkali, high-concentration salt mist and the like is improved, and the condition that a common cable sheath is easy to expand and crack in the extreme corrosion environments is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular, it relates to a kind of corrosion-resistant insulated power cable. BACKGROUND

[0002] Corrosion-resistant insulated power cable refers to the long-term stable operation in corrosive environment, effectively resist chemical attack, electrochemical corrosion and so on, maintain its electrical properties and mechanical properties.The cable is improved by using special material, structure design or protective measures, the adaptability of cable to corrosive environment is improved, the service life of cable is prolonged, and good insulation performance is also required to ensure the safety and stability of power transmission.

[0003] Although existing plastic, rubber and other sheath materials have certain corrosion resistance, but in some extreme corrosive environment, such as strong acid, strong alkali, high concentration salt fog, the corrosion resistance of these materials often cannot meet the requirements.For example, in the production workshop of chemical enterprise, cable may be in contact with various strong corrosive chemicals, ordinary plastic sheath cable may appear sheath expansion, cracking and other problems in a short time, which leads to cable insulation damage and causes safety accident.In order to solve the above technical problems, the present application proposes a new corrosion-resistant insulated power cable. SUMMARY

[0004] The present application proposes a kind of corrosion-resistant insulated power cable, the corrosion resistance of power cable in strong acid, strong alkali, high concentration salt fog and other extreme corrosive environment is improved, and the expansion and cracking of ordinary cable sheath in extreme corrosive environment are improved.

[0005] The technical scheme of the present application is as follows: In a first aspect, the present application proposes a kind of corrosion-resistant insulated power cable, which is sequentially provided with conductor layer, insulation layer and sheath layer from inside to outside, the insulation layer includes the following raw materials by weight: low density polyethylene 80-90 parts, magnesium hydroxide@calcium carbonate composite powder 35-45 parts, antioxidant 0.7-1 part, dicumyl peroxide 2.4-3 parts, zinc stearate 0.2-0.4 parts, polyethylene wax 0.4-0.6 parts;The sheath layer includes the following raw materials by weight: PVC resin 90-100 parts, magnesium hydroxide@calcium carbonate composite powder 30-35 parts, diisononyl phthalate 20-22 parts, calcium-zinc composite stabilizer 4-5 parts, antioxidant 1-2 parts, polyethylene wax 0.5-0.7 parts, calcium stearate 0.6-0.9 parts.

[0006] As a further technical solution, the preparation method of the magnesium hydroxide@calcium carbonate composite powder comprises: adding the nano calcium carbonate pretreated by silane coupling agent KH560 into the magnesium hydroxide after the zinc stearate melting coating in multiple times, vibration mixing treatment for 20-30 min, discharging and then passing through a 325 mesh screen to obtain the composite powder.

[0007] As a further technical solution, the zinc stearate melting coating step comprises: preheating and drying the magnesium hydroxide, then adding the 115-125℃ melting zinc stearate into the magnesium hydroxide, mixing at 250-350 rpm for 20-30 min, and passing through a 200 mesh screen after cooling.

[0008] As a further technical solution, the weight ratio of the magnesium hydroxide and the zinc stearate is 35-40:8-12.

[0009] As a further technical solution, the preparation method of the pretreated nano calcium carbonate comprises: hydrolyzing the silane coupling agent KH560 with anhydrous ethanol, then adding the nano calcium carbonate, and ultrasonic treatment at 300-350 W and 55-65℃ for 20-30 min.

[0010] As a further technical solution, the use amount ratio of the magnesium hydroxide after the zinc stearate melting coating, the silane coupling agent KH560, the anhydrous ethanol and the nano calcium carbonate is 60-70:0.2-0.24:20-24:10-12.

[0011] As a further technical solution, the magnesium hydroxide after the zinc stearate melting coating is added with the pretreated nano calcium carbonate in two times, and mixed in a vibration mill, the first time adding 50%, and treating at a frequency of 25-30 Hz for 10-12 min, then adding the remaining pretreated nano calcium carbonate, and increasing the frequency to 35-40 Hz for treating for 10-18 min.

[0012] As a further technical solution, the antioxidant comprises the antioxidant 1010 and the antioxidant 168 with a weight ratio of 2-4:1.

[0013] In the second aspect, the application provides a preparation method of a corrosion-resistant insulating power cable, comprising the following steps: (1) plasticizing the low-density polyethylene in a plasticizing machine, adding the antioxidant, the zinc stearate and the magnesium hydroxide@calcium carbonate composite powder in sequence, mixing for 8-10 min; adding the dicumyl peroxide after cooling, continuing mixing for 3-5 min, discharging, and granulating by a double-screw granulator at a temperature not higher than 120℃ to obtain an insulating layer master batch; (2) The conductor is preheated to 75-85 DEG C, the insulation layer master batch is extruded to cover the surface of the conductor to form an insulation layer, cooled in a water tank at 55-65 DEG C, and crosslinked by saturated steam treatment at 160-170 DEG C for 10-15 min and then cooled to room temperature; (3) The PVC resin, calcium-zinc stabilizer, 50% amount of diisononyl phthalate, is heated to 75-85 DEG C, stirred at 500-600 rpm for 10-15 min, the magnesium hydroxide@calcium carbonate composite powder and the remaining diisononyl phthalate are added, heated to 110-115 DEG C, and stirred for 3-5 min, polyethylene wax is added and stirred for 8-10 min, and then discharged after cooling to 40-45 DEG C, and extruded outside the insulation layer by using a single screw extruder to obtain the corrosion-resistant insulated power cable.

[0014] As a further technical solution, the temperature of the feeding zone of the single screw extruder is 140±2 DEG C, the temperature of the compression zone is 155±2 DEG C, the temperature of the metering zone is 160±2 DEG C, and the temperature of the die is 165±2 DEG C.

[0015] The working principle and beneficial effects of the present application are as follows: The magnesium hydroxide@calcium carbonate composite powder is obtained by adding the nano calcium carbonate pretreated by silane coupling agent KH560 into the magnesium hydroxide coated by zinc stearate in multiple times, and then vibration mixing. The core-shell structure design makes the magnesium hydroxide as the core and the nano calcium carbonate as the shell, forming a unique microstructure. In the extreme corrosion environment, the core-shell structure can play a synergistic effect. The magnesium hydroxide itself has certain flame-retardant and insulating properties, while the shell layer formed by the nano calcium carbonate can effectively block the penetration of corrosive media, protecting the internal magnesium hydroxide and other parts of the cable from corrosion, thereby improving the overall corrosion resistance of the cable. In addition, in the corrosion environment, single magnesium hydroxide or nano calcium carbonate filler has limitations in blocking corrosive media. In the magnesium hydroxide@calcium carbonate core-shell structure, the nano calcium carbonate shell tightly wraps the magnesium hydroxide core, forming a physical barrier. When the corrosive medium contacts the surface of the cable, it first needs to break through the barrier of the nano calcium carbonate shell. Due to the density and continuity of the shell layer, the penetration of the corrosive medium is greatly increased. At the same time, the magnesium hydroxide core can also play a certain buffering and resistance role, further preventing the corrosive medium from penetrating deeply into the cable, and the synergistic effect of the two significantly improves the blocking ability of the cable to the corrosive medium.

[0016] The stearic acid zinc in the stearic acid zinc coated magnesium hydroxide serves as a surfactant, and the hydrophilic group and the lipophilic group in the molecular structure of the stearic acid zinc can interact with the surface of the magnesium hydroxide and water molecules or other polymer matrices respectively. Through the melting coating, the stearic acid zinc forms a uniform coating layer on the surface of the magnesium hydroxide, changes the physical and chemical properties of the surface of the magnesium hydroxide, reduces the agglomeration tendency between the magnesium hydroxide particles, and enables the magnesium hydroxide to be better dispersed in the raw material system of the insulation layer and the sheath layer. In the insulation layer and the sheath layer, good dispersibility is crucial to improve the flame retardation and insulation performance of the cable. The uniformly dispersed magnesium hydroxide can fully exert its flame retardation effect, and when the cable encounters high temperature or fire, the magnesium hydroxide decomposes and absorbs heat, reduces the surrounding temperature, and at the same time releases water vapor to dilute the concentration of combustible gas, thereby achieving the effect of flame retardation. Moreover, the uniformly dispersed magnesium hydroxide can also form a continuous insulation network, reduce the generation of insulation defects, improve the volume resistivity of the cable, and enhance the insulation performance. The stearic acid zinc coating improves the dispersibility of the magnesium hydroxide, and further improves the overall flame retardation and insulation performance of the cable.

[0017] The silane coupling agent KH560 in the silane coupling agent KH560 modified nano calcium carbonate builds a "bridge" between the nano calcium carbonate and the polymer matrix, enhances the interfacial bonding force between them, and enables the nano calcium carbonate to be better dispersed in the polymer matrix and form a stable overall structure. After the interfacial bonding is enhanced, the gap between the nano calcium carbonate and the polymer matrix is reduced, and a more dense structure is formed. In an extreme corrosion environment, this dense structure can effectively prevent the penetration of corrosive media. The nano calcium carbonate particles are uniformly distributed in the polymer matrix, forming a micro barrier, and the corrosive medium needs to bypass these particles to continue to penetrate, greatly increasing the length and difficulty of the penetration path. At the same time, good interfacial bonding also ensures that the nano calcium carbonate and the polymer matrix will not easily occur debonding or separation under the action of external force or thermal stress, thereby maintaining the stability of the structure and further enhancing the barrier ability of the cable to corrosive media.

[0018] The present application adds the magnesium hydroxide coated by zinc stearate melt into the nano calcium carbonate pretreated by silane coupling agent KH560 twice, and mixes in the vibration mill. The first time is 50%, and the frequency is 25-30 Hz, and the processing time is 10-12 min. At this time, it is mainly to let part of the magnesium hydroxide and nano calcium carbonate preliminarily contact and mix. At lower frequency, there is enough time for particles to collide and adjust position, so that the two can be preliminarily uniformly distributed. Then add the remaining pretreated nano calcium carbonate, the frequency is raised to 35-40 Hz, and the processing time is 10-18 min. Increasing the frequency increases the collision frequency and energy between particles, so that the remaining magnesium hydroxide and nano calcium carbonate can be more fully mixed, further breaking the agglomerates that may exist, so that the composite powder reaches a more uniform dispersion state.

[0019] This segmented vibration mixing process not only helps to improve the dispersion, but also enhances the bonding strength of the magnesium hydroxide-carbonate core-shell structure. In the preliminary mixing stage at lower frequency, magnesium hydroxide and nano calcium carbonate begin to contact each other, forming a preliminary core-shell structure prototype. In the high-frequency mixing stage, the energy generated by the higher vibration frequency can promote the nano calcium carbonate to better wrap around the surface of the magnesium hydroxide, making the combination between the two more closely. This close core-shell combination structure can better resist external force and corrosion medium erosion during subsequent cable manufacturing and use, maintain the integrity of the structure, and thus improve the overall performance of the cable. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0021] It should be noted that the low-density polyethylene in the present application is purchased from PetroChina Jilin Petrochemical Company, and the brand is DFDA-7042; the PVC resin is purchased from Henan Haocun Chemical Industry Co., Ltd., and the brand is SG5; the polyethylene wax is purchased from Guangzhou Binlong Chemical Co., Ltd., and the model is D1100.

[0022] Example 1 The present embodiment provides a kind of corrosion-resistant insulated power cable, which is sequentially arranged conductor layer, insulating layer and sheath layer from inside to outside, The insulating layer includes the following raw materials by weight: 85 parts of low-density polyethylene, 40 parts of magnesium hydroxide-carbonate composite powder, 0.9 parts of antioxidant, 2.8 parts of dicumyl peroxide, 0.3 parts of zinc stearate and 0.5 parts of polyethylene wax; The sheath layer comprises the following raw materials by weight: 95 parts of PVC resin, 32 parts of magnesium hydroxide@calcium carbonate composite powder, 21 parts of diisononyl phthalate, 4.5 parts of calcium-zinc composite stabilizer, 1.5 parts of antioxidant, 0.6 parts of polyethylene wax, and 0.8 parts of calcium stearate; The preparation method of the magnesium hydroxide@calcium carbonate composite powder comprises the following steps: The magnesium hydroxide is preheated to 100°C and dried for 10 minutes, and then zinc stearate is added to the magnesium hydroxide at 120°C, mixed at 300 rpm for 25 minutes, and then sieved through a 200-mesh screen to obtain the zinc stearate melt-coated magnesium hydroxide; the weight ratio of the magnesium hydroxide to the zinc stearate is 38:10; The silane coupling agent KH560 is hydrolyzed with anhydrous ethanol, and then the nano calcium carbonate is added, and the pre-processed nano calcium carbonate is obtained by ultrasonic treatment at 320 W and 60°C for 25 minutes; The pre-processed nano calcium carbonate treated by the silane coupling agent KH560 is added to the zinc stearate melt-coated magnesium hydroxide in two portions, and mixed in a vibration mill, 50% of the pre-processed nano calcium carbonate is added at a frequency of 28 Hz for 11 minutes, and then the remaining pre-processed nano calcium carbonate is added, the frequency is increased to 38 Hz, and the processing time is 14 minutes, and then the material is sieved through a 325-mesh screen to obtain the composite powder: the weight ratio of the zinc stearate melt-coated magnesium hydroxide, the silane coupling agent KH560, the anhydrous ethanol, and the nano calcium carbonate is 65:0.22:22:11; The antioxidant comprises antioxidant 1010 and antioxidant 168 in a weight ratio of 3:1; The preparation method of the corrosion-resistant insulated power cable comprises the following steps: (1) The low-density polyethylene is plasticized in a 110°C internal mixer, and then the antioxidant, zinc stearate, and the magnesium hydroxide@calcium carbonate composite powder are added in sequence, and mixed for 9 minutes; the temperature is lowered to 100°C, and dicumyl peroxide is added, and the mixing is continued for 4 minutes before the material is discharged, and then the material is granulated by a double-screw granulator at a temperature of 120°C to obtain the insulation layer masterbatch; (2) The conductor is preheated to 80°C, the insulation layer masterbatch is extruded and coated on the surface of the conductor to form an insulation layer, the material is cooled in a 60°C water tank, and then crosslinking is performed by saturated steam treatment at 165°C for 12 minutes before the material is cooled to room temperature; (3) The PVC resin, the calcium-zinc stabilizer, and 50% of the diisononyl phthalate are heated to 80°C, and stirred at 550 rpm for 12 minutes, and then the magnesium hydroxide@calcium carbonate composite powder and the remaining diisononyl phthalate are added, and the temperature is increased to 112°C for continued stirring for 4 minutes, and then the polyethylene wax is added and stirred for 9 minutes, and the temperature is lowered to 42°C before the material is discharged, and then the material is extruded and coated outside the insulation layer by using a single-screw extruder, the temperature of the feeding zone is 140°C, the temperature of the compression zone is 155°C, the temperature of the metering zone is 160°C, the temperature of the die head is 165°C, and the material is water-cooled and shaped to obtain the corrosion-resistant insulated power cable.

[0023] Embodiment 2 The embodiment provides a corrosion-resistant insulated power cable, which is sequentially provided with a conductor layer, an insulation layer and a sheath layer from inside to outside, The insulation layer comprises the following raw materials in parts by weight: 80 parts of low-density polyethylene, 35 parts of magnesium hydroxide@calcium carbonate composite powder, 0.7 parts of antioxidant, 2.4 parts of dicumyl peroxide, 0.2 parts of zinc stearate and 0.4 parts of polyethylene wax; The sheath layer comprises the following raw materials in parts by weight: 90 parts of PVC resin, 30 parts of magnesium hydroxide@calcium carbonate composite powder, 20 parts of diisononyl phthalate, 4 parts of calcium-zinc composite stabilizer, 1 part of antioxidant, 0.5 part of polyethylene wax and 0.6 part of calcium stearate; The preparation method of the magnesium hydroxide@calcium carbonate composite powder comprises the following steps: The magnesium hydroxide is preheated to 100 DEG C and dried for 10 minutes, and then zinc stearate is added to the magnesium hydroxide and mixed at 250 rpm for 20 minutes, and the zinc stearate-melted coated magnesium hydroxide is obtained after being cooled and sieved through a 200-mesh sieve; the weight ratio of the magnesium hydroxide to the zinc stearate is 35:8; The silane coupling agent KH560 is hydrolyzed with anhydrous ethanol, and then the nano calcium carbonate is added, and the pretreated nano calcium carbonate is obtained by ultrasonic treatment at 300 W and 55 DEG C for 20 minutes; The zinc stearate-melted coated magnesium hydroxide is added with the pretreated nano calcium carbonate by the silane coupling agent KH560 in two times, and the mixture is mixed in a vibration mill, 50% of the pretreated nano calcium carbonate is added in the first time, and the mixture is treated at a frequency of 25 Hz for 10 minutes, then the remaining pretreated nano calcium carbonate is added, the frequency is increased to 35 Hz, and the mixture is treated for 10 minutes, and the composite powder is obtained after being sieved through a 325-mesh sieve, the weight ratio of the zinc stearate-melted coated magnesium hydroxide, the silane coupling agent KH560, the anhydrous ethanol and the nano calcium carbonate is 60:0.2:20:10; The antioxidant comprises antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1; The preparation method of the corrosion-resistant insulated power cable comprises the following steps: (1) The low-density polyethylene is plasticized in a 110 DEG C internal mixer, and then the antioxidant, the zinc stearate and the magnesium hydroxide@calcium carbonate composite powder are sequentially added and mixed for 8 minutes; the temperature is reduced to 100 DEG C, the dicumyl peroxide is added, and the mixture is continuously mixed for 3 minutes and then discharged; the insulation layer master batch is obtained by granulating the mixture through a double-screw granulator at a temperature of 120 DEG C; (2) The conductor is preheated to 75 DEG C, the insulation layer master batch is extruded and coated on the surface of the conductor to form the insulation layer, the insulation layer is cooled in a 55 DEG C water tank, and the cross-linking is performed by treating the insulation layer in saturated steam at 160 DEG C for 10 minutes, and then the insulation layer is cooled to room temperature; (3) PVC resin, calcium-zinc stabilizer, 50% of diisononyl phthalate, heated to 75℃, stirring at 500 rpm for 10 min, adding magnesium hydroxide@calcium carbonate composite powder and the rest of diisononyl phthalate, heated to 110℃ continue to stir for 3 min, adding polyethylene wax stirring 8 min, cooling to 40℃ discharge, using single screw extruder extrusion coated outside the insulation layer, feeding zone temperature is 140℃, compression zone temperature is 155℃, metering zone temperature is 160℃, die temperature is 165℃, water cooling to get corrosion-resistant insulation power cable.

[0024] Example 3 The embodiment provides a kind of corrosion-resistant insulation power cable, sequentially set conductor layer, insulation layer and sheath layer from inside to outside, Insulation layer includes the following raw materials by weight: low density polyethylene 90 parts, magnesium hydroxide@calcium carbonate composite powder 45 parts, antioxidant 1 part, dicumyl peroxide 3 parts, zinc stearate 0.4 parts, polyethylene wax 0.6 parts; Sheath layer includes the following raw materials by weight: PVC resin 100 parts, magnesium hydroxide@calcium carbonate composite powder 35 parts, diisononyl phthalate 22 parts, calcium-zinc composite stabilizer 5 parts, antioxidant 2 parts, polyethylene wax 0.7 parts, calcium stearate 0.9 parts; Wherein, the preparation method of magnesium hydroxide@calcium carbonate composite powder includes: Magnesium hydroxide is preheated to 100℃ and dried for 10 minutes, 125℃ zinc stearate is added to magnesium hydroxide, mixed at 350 rpm for 30 min, and sieved through 200 mesh after cooling to obtain zinc stearate melt coated magnesium hydroxide;The weight ratio of magnesium hydroxide and zinc stearate is 40:8-12; Silane coupling agent KH560 is hydrolyzed with anhydrous ethanol, and then nano calcium carbonate is added, and the pretreated nano calcium carbonate is obtained by ultrasonic treatment at 350 W and 65℃ for 30 min; The pretreated nano calcium carbonate after silane coupling agent KH560 is added to the zinc stearate melt coated magnesium hydroxide in two times, and mixed in a vibration mill, the first 50% is added, and treated at a frequency of 30 Hz for 12 min, then the rest of the pretreated nano calcium carbonate is added, the frequency is raised to 40 Hz, and treated for 18 min, sieved through 325 mesh after discharge, to obtain composite powder: the amount ratio of zinc stearate melt coated magnesium hydroxide, silane coupling agent KH560, anhydrous ethanol and nano calcium carbonate is 70:0.24:24:12; Wherein, the antioxidant includes antioxidant 1010 and antioxidant 168 in a weight ratio of 4:1; The preparation method of corrosion-resistant insulation power cable, the steps include: (1) Low density polyethylene is plasticized in a 110℃ internal mixer, antioxidant, zinc stearate and magnesium hydroxide@calcium carbonate composite powder are added in turn, and mixed for 10 min; cooled to 100℃, add dicumyl peroxide, continue to mix for 5 min, then discharge, through the double screw granulator at a temperature not higher than 120℃, get the insulation layer masterbatch; (2) The conductor is preheated to 85℃, the insulation layer masterbatch is extruded to cover the surface of the conductor to form an insulation layer, cooled in a 65℃ water tank, crosslinked by saturated steam at 170℃ for 15 min, and then cooled to room temperature; (3) PVC resin, calcium zinc stabilizer, 50% amount of diisononyl phthalate, are heated to 85℃, stirred at 600 rpm for 15 min, add magnesium hydroxide@calcium carbonate composite powder and the remaining diisononyl phthalate, heat to 115℃ continue to stir for 5 min, add polyethylene wax and stir for 10 min, cool to 45℃ discharge, use single screw extruder to extrude and cover outside the insulation layer, the temperature of feeding zone is 140℃, the temperature of compression zone is 155℃, the temperature of metering zone is 160℃, the temperature of die head is 165℃, water cooling and shaping to get corrosion-resistant insulated power cable.

[0025] Comparative Example 1 Based on the adjustment of Example 1, the difference from Example 1 is that the magnesium hydroxide@calcium carbonate composite powder is replaced by equal amount of zinc stearate melt-coated magnesium hydroxide.

[0026] Comparative Example 2 Based on the adjustment of Example 1, the difference from Example 1 is that the magnesium hydroxide@calcium carbonate composite powder is replaced by equal amount of magnesium hydroxide.

[0027] Comparative Example 3 Based on the adjustment of Example 1, the difference from Example 1 is that the magnesium hydroxide@calcium carbonate composite powder is replaced by equal amount of silane coupling agent KH560 pretreated nano calcium carbonate.

[0028] Comparative Example 4 Based on the adjustment of Example 1, the difference from Example 1 is that the magnesium hydroxide@calcium carbonate composite powder is replaced by equal amount of nano calcium carbonate.

[0029] Comparative Example 5 Based on the adjustment of Example 1, the difference from Example 1 is that in the preparation of magnesium hydroxide@calcium carbonate composite powder, the amount ratio of zinc stearate melt-coated magnesium hydroxide to nano calcium carbonate is adjusted to 70:6.

[0030] Comparative Example 6 On the basis of Example 1, adjustments were made, and different from Example 1, the magnesium hydroxide after zinc stearate melt coating was directly added to the nano calcium carbonate pretreated by silane coupling agent KH560.

[0031] Test Example 1: The corrosion-resistant insulated power cables prepared in the foregoing Examples 1-3 and Comparative Examples 1-6 were tested as follows: Volume resistivity: The resistivity at 20°C was determined according to GB / 15662 standard; Corrosion resistance: The sheath sheet (100mm x 100mm x 2mm) was placed in 20% H2SO4, 20% NaOH, 10% NaCl solution, soaked at 23°C for 168h, washed with water, and dried with filter paper, and the mass change rate was tested; Thermal cycle delamination: The cable sample was subjected to-40°C~105°C cold and heat cycle for 100 times, and whether the cable sample had cracks and pulverization was observed; The test results are shown in Table 1 below: Table 1

[0032] According to the foregoing data, it can be seen that the magnesium hydroxide@calcium carbonate core-shell structure in Examples 1-3 has a volume resistivity of >1.9 x 10 5 Ω·cm, and a corrosion solution mass change rate of ≤2.0%, which is much better than that of the single filler in Comparative Example 1-4; the zinc stearate coating improves the dispersibility of magnesium hydroxide and enhances the flame retardation and insulation; the KH560 modified calcium carbonate enhances the interface bonding and blocks the penetration of corrosion medium.

[0033] Comparative Example 1 only uses zinc stearate melt coated magnesium hydroxide, which leads to a significant decrease in insulation, corrosion resistance and thermal stability. The volume resistivity is 43% lower than that of Example 1, due to the lack of reinforcing effect of nano calcium carbonate. The mass change rate of acid mist / alkali mist / salt mist is much higher than that of Example 1, because the core-shell structure blocks the penetration of corrosion medium. After heat cycle, slight pulverization occurs, because the single filler leads to poor matrix compatibility.

[0034] Comparative Example 2 directly uses uncoated magnesium hydroxide, and the volume resistivity (0.8 x 10 5 Ω·cm) is the lowest among all samples, because the uncoated magnesium hydroxide has poor dispersibility, forming insulation defects. The corrosion resistance is very weak, because the unmodified filler is easily eroded by corrosion medium. After heat cycle, obvious cracks occur, because the filler has insufficient interface bonding with the matrix.

[0035] Comparative Example 3 only uses silane coupling agent KH560 modified nano calcium carbonate, insufficient insulation and corrosion resistance. The volume resistivity is low, and the flame-retardant insulation synergistic effect of magnesium hydroxide is lacking. The mass change rate of acid mist / alkali mist / salt mist is higher than that of Example 1, but better than that of Comparative Examples 1-2, because the modified calcium carbonate partially improves corrosion resistance. Partial pulverization after thermal cycling, because a single filler cannot form a complete protective network.

[0036] Comparative Example 4 uses unmodified nano calcium carbonate, and the comprehensive performance is poor, with high risk of failure. The volume resistivity is the lowest among all samples, because the unmodified calcium carbonate is severely agglomerated, which destroys the insulation continuity. The corrosion resistance is extremely weak, which is 3 times higher than that of Example 1, because the untreated filler is easily dissolved by chemical media. Severe cracking after thermal cycling, because the filler has extremely poor compatibility with the matrix.

[0037] Comparative Example 5 has too low a proportion of nano calcium carbonate in the composite powder, and the reinforcing effect is insufficient, resulting in a partial decrease in performance. The volume resistivity is lower than that of Example 1, because the nano calcium carbonate content is insufficient to fully improve the insulation. The corrosion resistance decreases by 70% compared to Example 1, because the core-shell structure is not complete. Slight delamination after thermal cycling, because the stress concentration is caused by the unbalanced proportion of fillers.

[0038] Comparative Example 6 simplifies the mixing process and does not segment vibration, resulting in insufficient dispersion uniformity. The performance is slightly better than that of a single filler but not as good as that of the example. The volume resistivity is lower than that of Example 1, because direct mixing leads to uneven dispersion of fillers. The corrosion resistance is better than that of Comparative Examples 1-5, but 50% higher than that of Example 1, because the unsegmented high-frequency mixing weakens the core-shell bonding strength. No delamination after thermal cycling, which proves that the basic process can still maintain mechanical stability.

[0039] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A corrosion-resistant insulated power cable, characterized in that: From the inside to the outside, a conductor layer, an insulating layer and a sheath layer are sequentially arranged. The insulating layer comprises the following raw materials in parts by weight: 80-90 parts of low-density polyethylene, 35-45 parts of magnesium hydroxide @ calcium carbonate composite powder, 0.7-1 part of antioxidant, 2.4-3 parts of dicumyl peroxide, 0.2-0.4 parts of zinc stearate, and 0.4-0.6 parts of polyethylene wax; the sheath layer comprises the following raw materials in parts by weight: 90-100 parts of PVC resin, 30-35 parts of magnesium hydroxide @ calcium carbonate composite powder, 20-22 parts of diisononyl phthalate, 4-5 parts of calcium zinc composite stabilizer, 1-2 parts of antioxidant, 0.5-0.7 parts of polyethylene wax, and 0.6-0.9 parts of calcium stearate.

2. A corrosion-resistant insulated power cable according to claim 1, characterized in that: The preparation method of the magnesium hydroxide@calcium carbonate composite powder comprises: adding nano calcium carbonate pretreated with a silane coupling agent KH560 to magnesium hydroxide melt-coated with zinc stearate in multiple portions, vibrating and mixing for 20-30 minutes, and filtering the discharged material through a 325-mesh sieve to obtain a composite powder.

3. The corrosion-resistant insulated power cable according to claim 2, characterized in that: The zinc stearate melt coating step comprises: preheating and drying magnesium hydroxide, then adding 115-125° C. melted zinc stearate into the magnesium hydroxide, mixing at 250-350 rpm for 20-30 minutes, cooling, and passing through a 200-mesh sieve.

4. The corrosion-resistant insulated power cable according to claim 3, characterized in that: The weight ratio of the magnesium hydroxide to the zinc stearate is 35-40:8-12.

5. The corrosion-resistant insulated power cable according to claim 2, characterized in that: The preparation method of the pretreated nano-calcium carbonate comprises: hydrolyzing the silane coupling agent KH560 with anhydrous ethanol, then adding the nano-calcium carbonate, and ultrasonically treating the mixture at 300-350W and 55-65°C for 20-30 minutes.

6. The corrosion-resistant insulated power cable according to claim 5, characterized in that: The ratio of magnesium hydroxide, silane coupling agent KH560, anhydrous ethanol and nano calcium carbonate after the zinc stearate is melt-coated is 60-70: 0.2-0.24：20-24：10-12。 7. The corrosion-resistant insulated power cable according to claim 2, characterized in that: The magnesium hydroxide after melt coating with zinc stearate is added to the nano-calcium carbonate pretreated with silane coupling agent KH560 in two times and mixed in a vibration mill. 50% is added for the first time and processed at a frequency of 25-30 Hz for 10-12 minutes. Then, the remaining pretreated nano-calcium carbonate is added and the frequency is increased to 35-40 Hz and processed for 10-18 minutes.

8. The corrosion-resistant insulated power cable according to claim 1, characterized in that: The antioxidant includes antioxidant 1010 and antioxidant 168 in a weight ratio of 2-4:

1.

9. A method for preparing a corrosion-resistant insulated power cable according to any one of claims 1 to 8, characterized in that the steps include: (1) Plasticize low-density polyethylene in an internal mixer, add antioxidant, zinc stearate and magnesium hydroxide@calcium carbonate composite powder in sequence, and mix for 8-10 minutes; Cool down and add dicumyl peroxide, continue mixing for 3-5 minutes, then discharge the material and granulate it through a twin-screw granulator at a temperature not higher than 120°C to obtain the insulation layer masterbatch; (2) Preheat the conductor to 75-85℃, extrude and coat the insulation masterbatch on the surface of the conductor to form an insulation layer, cool it in a 55-65℃ water tank, treat it with saturated steam at 160-170℃ for 10-15 minutes for cross-linking, and then cool it to room temperature; (3) PVC resin, calcium zinc stabilizer, and 50% diisononyl phthalate are heated to 75-85°C and stirred at 500-600 rpm for 10-15 minutes. Magnesium hydroxide@calcium carbonate composite powder and the remaining diisononyl phthalate are added and heated to 110-115°C and stirred for 3-5 minutes. Polyethylene wax is added and stirred for 8-10 minutes. The material is cooled to 40-45°C and discharged. The material is extruded and coated on the outside of the insulation layer using a single-screw extruder and water-cooled to obtain the corrosion-resistant insulated power cable.

10. The method for preparing the corrosion-resistant insulated power cable according to claim 9, characterized in that: The temperature of the feeding zone of the single-screw extruder is 140±2°C, the temperature of the compression zone is 155±2°C, the temperature of the metering zone is 160±2°C, and the temperature of the die head is 165±2°C.

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