Cable semiconductive shielding material based on polyolefin elastomer ionomer compound system and preparation method thereof

Abstract

The invention discloses a cable semi-conductive shielding material based on a polyolefin elastomer ionomer compound system and a preparation method of the cable semi-conductive shielding material, and belongs to the field of cables. Aiming at the problems of high addition amount of conductive filler, complex process, high volume resistivity and the like of a cable shielding material in the prior art, in the technical scheme of the invention, in a mixing stage, POE / Zn-EMAA is premixed, and carboxylated graphene microchips FGMP and zinc oxide whiskers are synchronously added; single-screw extrusion granulation is performed, the melt temperature is reduced by 20 DEG C, and the graphene structure is prevented from being damaged; keeping the temperature of the obtained granules at 60-80 DEG C, and adding a cross-linking agent (DCP / BIBP) for post-absorption; the preparation method provided by the invention has the advantages of lower conductive filler addition amount, lower volume resistivity and the like, the high melt index adapts to high-speed extrusion, and the production process is simple.

Description

Technical Field

[0001] This invention relates to a semiconductive shielding material for cables based on a polyolefin elastomer ionomer composite system and its preparation method, belonging to the field of cables. Background Technology

[0002] With the rapid development of my country's economy and the increasing demand for electricity, the use of high-voltage power cables is growing, and the industry is continuously developing towards higher voltage, ultra-high voltage, larger capacity, and more environmentally friendly technologies. Semi-conductive shielding material is a special composite material mainly composed of conductive fillers, matrix resin, and additives. It has a certain degree of conductivity, but is not completely conductive, hence the name "semi-conductive." Semi-conductive shielding material is mainly used in various power cables, communication cables, and control cables. In these cables, the semi-conductive shielding material acts as a shielding layer, effectively improving the cable's anti-interference capability and transmission quality, optimizing the electric field distribution, and preventing partial discharge.

[0003] Traditional EVA / EBA system semiconductive shielding materials have some defects and are not suitable for use as conductor shielding layers in 66kV and above cross-linked polyethylene (XLPE) cables.

[0004] Traditional EVA / EBA system semiconducting shielding materials have a high amount of conductive filler added. Traditional cable semiconducting shielding materials require 30% to 40% carbon black filler by mass, resulting in poor melt flowability, rough extrusion surface, and limited elongation at break of the finished product.

[0005] The melt flow index of traditional EVA / EBA system semiconductive shielding materials is not suitable for high-speed extrusion production, and the production efficiency is low and the production process is relatively complex.

[0006] Traditional EVA / EBA semiconductive shielding materials have high volume resistivity, while the volume resistivity of the film decreases with increasing temperature. At high temperatures, molecular thermal motion intensifies, increasing electron and ion mobility and enhancing conductivity. At room temperature, the resistivity of EVA is approximately 3-5 Ω·m.

[0007] Traditional EVA / EBA system semiconductive shielding materials have complex manufacturing processes, require many additives, and increase energy consumption and cost. Summary of the Invention

[0008] To address the shortcomings of existing technologies, a cable semiconductive shielding material based on a polyolefin elastomer ionomer composite system and its preparation method are proposed. This system forms a low-threshold conductive system composed of a polyolefin elastomer (POE) and a ethylene-zinc methacrylate ionomer (Zn-EMAA) composite resin matrix, combined with functionalized graphene microplates (FGMP).

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is a method for preparing a cable semiconductive shielding material based on a polyolefin elastomer ionomer composite system, comprising the following steps: 1) During the mixing stage, POE and Zn-EMAA are premixed, and carboxylated graphene micro-flakes FGMP and zinc oxide whiskers are added simultaneously to obtain POE / Zn-EMAA premix. 2) Single-screw extrusion granulation: The POE / Zn-EMAA premix is ​​granulated after the temperature is reduced by 20°C; 3) Keep the obtained granules at 60-80℃ and add a crosslinking agent for post-absorption.

[0010] In the optimized preparation method of the above-mentioned cable semiconductive shielding material based on polyolefin elastomer ionomer complex system, the temperature is maintained at 160°C for 5 minutes during the mixing stage in step 1). During single-screw extrusion granulation in step 2), the extrusion granulation temperature is 170℃; In step 3), the added crosslinking agent includes one or a mixture of two of DCP and BIBP.

[0011] In the optimized preparation method of the above-mentioned cable semiconductive shielding material based on polyolefin elastomer ionomer complex system, the weight parts of POE are 60-70, the weight parts of Zn-EMAA are 30-40, the weight parts of FGMP are 3-8, the weight parts of zinc oxide whiskers are 5-10, and the weight parts of crosslinking agent are 0.5.

[0012] In the optimized preparation method of the above-mentioned cable semiconductive shielding material based on polyolefin elastomer ionomer complex system, the weight parts of POE are 65, the weight parts of Zn-EMAA are 35, the weight parts of FGMP are 5, the weight parts of zinc oxide whiskers are 8, and the weight parts of crosslinking agent are 0.5.

[0013] In the optimized preparation method of the cable semiconductive shielding material based on the polyolefin elastomer ionomer complex system, the absorption time in step 3) is 2 hours.

[0014] In the optimized preparation method of the above-mentioned cable semiconductive shielding material based on the polyolefin elastomer ionomer compound system, during single-screw extrusion granulation in step 2), a cooling jacket is set at the feed inlet of the extruder, and chilled water at 15-20°C is introduced at a flow rate of 15 L / min to pre-cool the POE / Zn-EMAA premix (initial temperature of POE / Zn-EMAA premix is ​​25°C). This reduces the temperature of the material entering the barrel to 15-20°C, reduces the heating load on the barrel, and prevents the material from sticking together at the feed inlet due to excessive temperature. At the same time, the screw speed is set to 40-50 r / min to reduce the shear rate between the screw and the material, thereby reducing frictional heat generation. The single screw has a length-to-diameter ratio of 20:1; the extrusion chamber from the feed inlet to the die is divided into multiple zones with sequentially set temperatures: 140℃ (Zone 1, feed section), 155℃ (Zone 2, front section of compression), 165℃ (Zone 3, rear section of compression), 170℃ (Zone 4, metering section), and 168℃ (Zone 5, die). The temperature of each zone is precisely controlled by a PID temperature control system (temperature control accuracy ±1℃) to avoid local overheating, resulting in an overall barrel temperature reduction of 15-20℃ compared to traditional processes.

[0015] In the optimized method for preparing the cable semiconductive shielding material based on the polyolefin elastomer ionomer complex system, in step 3), the crosslinking agent and white oil are mixed and stirred (at a speed of 300 r / min for 15 min to prepare a crosslinking agent white oil solution). Equipment inspection steps: Check the mixer's vacuum system (vacuum degree must reach -0.09MPa or above), temperature control system (temperature control accuracy ±1℃), and stirring system (speed adjustable range 0-60r / min) to ensure the equipment is operating normally; clean the inside of the mixer thoroughly to avoid residual other materials and impurities; Granule feeding and preheating steps: Feed the qualified granules after extrusion and granulation into the mixer, close the feed inlet, turn on the heating system, set the temperature to 50-70℃, the rotation speed to 4-6r / min, and preheat for 30min. During this period, the temperature of the granules is monitored in real time by the temperature sensor built into the mixer. When the temperature reaches the set value, stop heating and maintain a constant temperature.

[0016] Crosslinking agent spraying and vacuum penetration steps: Turn on the high-pressure atomizing nozzle, and spray the crosslinking agent white oil solution evenly on the surface of the granules at a rate of 5 mL / min. The amount of crosslinking agent white oil solution sprayed is 1-1.5% of the granule mass, corresponding to a solution mass of 5%-7.5%, and the spraying time is 40-60 min. After the spraying is completed, immediately turn on the vacuum system and reduce the pressure inside the mixer to -0.08 to -0.1 MPa, and maintain it for 30 minutes. During this period, monitor the pressure in real time with a vacuum gauge to ensure that the vacuum level is stable and to avoid a decrease in the penetration effect due to leakage. Constant temperature stirring and absorption: Turn off the vacuum system, adjust the mixer speed to 10 r / min, turn on the heating system, maintain the temperature at 75℃, and carry out constant temperature stirring and absorption for 2 hours; At 1 hour and 1.5 hours of absorption, the vacuum system was turned on for 10 minutes to remove the gas inside the pellets. After 2 hours of absorption, the heating system was turned off, the cooling jacket of the mixer was turned on, and circulating cooling water at 25°C was introduced to lower the temperature of the pellets to room temperature (25°C) for 1 hour.

[0017] The optimized method for preparing the above-mentioned cable semiconductive shielding material based on the polyolefin elastomer ionomer complex system involves mixing the crosslinking agent and white oil at a mass ratio of 1:5 and stirring at 300 r / min for 15 min to prepare a 20% crosslinking agent white oil solution. When the crosslinking agent is BIBP, the crosslinking agent is mixed with white oil and stirred at 300 r / min for 15 min to prepare a 15% crosslinking agent white oil solution.

[0018] The optimized cable semiconductive shielding material based on the polyolefin elastomer ionomer complex system is prepared using the above-described preparation method.

[0019] In the optimized cable semiconductive shielding material based on the polyolefin elastomer ionomer complex system, zinc ions in Zn-EMAA complex with FGMP carboxyl groups to form an ionic-π bond double cross-linked conductive network.

[0020] The beneficial effects of this application are as follows: This application discloses a method for preparing cable semiconductive shielding materials based on a polyolefin elastomer ionomer composite system. In ethylene-zinc methacrylate ionomer (Zn-EMAA), zinc ions complex with the carboxyl groups of graphene microplates (FGMP) to form an "ionic bond-π bond" double cross-linked conductive network.

[0021] After cross-linking, POE / Zn-EMAA forms an island structure, creating a matrix that achieves a balance between rigidity and flexibility, balancing fluidity, strength, and high electrical conductivity, thus improving melt strength. Its strength and elongation are higher than those of EVA and EBA.

[0022] Carboxylated graphene microplates (FGMP) overcome the bottleneck of low-addition conductivity through ionic bond anchoring, indirectly increasing extrusion flowability and improving the speed of cable production lines. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the combined functional monomer structure of Zn-EMAA ionomer and carboxylated graphene. Detailed Implementation

[0024] This application discloses a method for preparing a cable semiconductive shielding material based on a polyolefin elastomer ionomer composite system. The main equipment involved in the preparation process includes an internal mixer and a single-screw extruder, eliminating the need for twin-screw high-shear equipment.

[0025] The preparation method of the cable semiconductive shielding material based on the polyolefin elastomer ionomer composite system of this application mainly includes the following steps; 1) During the mixing stage, POE and Zn-EMAA are premixed, and carboxylated graphene micro-flakes FGMP and zinc oxide whiskers are added simultaneously; 2) Single-screw extrusion granulation: Melt temperature reduced by 20℃; 3) Keep the obtained granules at 60-80℃ and add a crosslinking agent for post-absorption.

[0026] During single-screw extrusion granulation in step 2), a cooling jacket is installed at the feed inlet of the extruder, and chilled water at 15-20°C is introduced at a flow rate of 15 L / min to pre-cool the POE / Zn-EMAA premix (initial temperature of POE / Zn-EMAA premix is ​​25°C). This reduces the temperature of the material as it enters the barrel to 15-20°C, reducing the heating load on the barrel and preventing the material from sticking together at the feed inlet due to excessive temperature. At the same time, the screw speed is set to 40-50 r / min to reduce the shear rate between the screw and the material, thereby reducing frictional heat generation. The single screw has a length-to-diameter ratio of 20:1; the extrusion chamber from the feed inlet to the die is divided into multiple zones with sequentially set temperatures: 140℃ (Zone 1, feed section), 155℃ (Zone 2, front section of compression), 165℃ (Zone 3, rear section of compression), 170℃ (Zone 4, metering section), and 168℃ (Zone 5, die). The temperature of each zone is precisely controlled by a PID temperature control system (temperature control accuracy ±1℃) to avoid local overheating, resulting in an overall barrel temperature reduction of 15-20℃ compared to traditional processes.

[0027] In step 3), the crosslinking agent is mixed with white oil and stirred (at a speed of 300 r / min for 15 min) to prepare a crosslinking agent-white oil solution; Equipment inspection steps: Check the mixer's vacuum system (vacuum degree must reach -0.09MPa or above), temperature control system (temperature control accuracy ±1℃), and stirring system (speed adjustable range 0-60r / min) to ensure the equipment is operating normally; clean the inside of the mixer thoroughly to avoid residual other materials and impurities; Granule feeding and preheating steps: Feed the qualified granules after extrusion and granulation into the mixer, close the feed inlet, turn on the heating system, set the temperature to 50-70℃, the rotation speed to 4-6r / min, and preheat for 30min. During this period, the temperature of the granules is monitored in real time by the temperature sensor built into the mixer. When the temperature reaches the set value, stop heating and maintain a constant temperature.

[0028] Crosslinking agent spraying and vacuum penetration steps: Turn on the high-pressure atomizing nozzle, and spray the crosslinking agent white oil solution evenly on the surface of the granules at a rate of 5 mL / min. The amount of crosslinking agent white oil solution sprayed is 1-1.5% of the granule mass, corresponding to a solution mass of 5%-7.5%, and the spraying time is 40-60 min. After the spraying is completed, immediately turn on the vacuum system and reduce the pressure inside the mixer to -0.08 to -0.1 MPa, and maintain it for 30 minutes. During this period, monitor the pressure in real time with a vacuum gauge to ensure that the vacuum level is stable and to avoid a decrease in the penetration effect due to leakage. Constant temperature stirring and absorption: Turn off the vacuum system, adjust the mixer speed to 10 r / min, turn on the heating system, maintain the temperature at 75℃, and carry out constant temperature stirring and absorption for 2 hours; At 1 hour and 1.5 hours of absorption, the vacuum system was turned on for 10 minutes to remove the gas inside the pellets. After 2 hours of absorption, the heating system was turned off, the cooling jacket of the mixer was turned on, and circulating cooling water at 25°C was introduced to lower the temperature of the pellets to room temperature (25°C) for 1 hour.

[0029] When the crosslinking agent is DCP, the crosslinking agent and white oil are mixed at a mass ratio of 1:5 and stirred at 300 r / min for 15 min to prepare a 20% crosslinking agent white oil solution. When the crosslinking agent is BIBP, the crosslinking agent is mixed with white oil and stirred at 300 r / min for 15 min to prepare a 15% crosslinking agent white oil solution.

[0030] The technical solution of this application will be described in detail below with reference to specific embodiments.

[0031] In one embodiment of this application, during the mixing stage, 65 parts by weight of polyolefin elastomer POE (Engage 8180) and 35 parts by weight of ethylene-zinc methacrylate ionomer (Zn-EMAA) are premixed, and 5 parts by weight of carboxylated graphene microplates FGMP and 8 parts by weight of zinc oxide whiskers ZnOw are added simultaneously. The mixture is then mixed at 160°C for 5 minutes to obtain material one.

[0032] The material obtained above is added to a single-screw extrusion granulation equipment for extrusion granulation. The melt temperature is reduced by 20°C to avoid damage to the graphene structure, i.e., extrusion granulation is carried out at 170°C.

[0033] The resulting granules are kept at 60-80℃, and 0.5 parts by weight of DCP are added. The mixture is then absorbed at 69-80℃ for 2 hours.

[0034] This embodiment yields a cable semiconductive shielding material based on a polyolefin elastomer ionomer complex system, wherein zinc ions in Zn-EMAA complex with FGMP carboxyl groups to form an ionic-π bond double crosslinked conductive network.

[0035] In another embodiment of this application, during the mixing stage, 60 parts by weight of polyolefin elastomer POE (Engage 8180) and 30 parts by weight of ethylene-zinc methacrylate ionomer (Zn-EMAA) are premixed, and 3 parts by weight of carboxylated graphene microplates FGMP and 5 parts by weight of zinc oxide whiskers ZnOw are added simultaneously. The mixture is then mixed at 160°C for 5 minutes to obtain material one.

[0036] The material obtained above is added to a single-screw extrusion granulation equipment for extrusion granulation. The melt temperature is reduced by 20°C to avoid damage to the graphene structure, i.e., extrusion granulation is carried out at 170°C.

[0037] The resulting granules are kept at 60-80℃, and 0.5 parts by weight of BIBP are added. The mixture is then absorbed at 75℃ for 2 hours.

[0038] The structure of the Zn-EMAA ionomer and carboxylated graphene combined functional monomer obtained by the method of this application is as follows: Figure 1 As shown, it achieves combined conductive functions.

[0039] The technical solution of this application shortens the mixing time to 8 minutes, which is significantly shorter than the traditional mixing time of ≥15 minutes. It also reduces energy consumption by 40% (no high shear section required).

[0040] Furthermore, in the technical solution of this application, the POE / Zn-EMAA compound achieves a "rigid and flexible" matrix, balancing fluidity, strength and high conductivity; the carboxylated graphene microplates (FGMP) are anchored by ionic bonds, breaking through the conductivity bottleneck of low addition amount, indirectly increasing extrusion fluidity and improving the speed of cable production line.

[0041] The cable semiconducting shielding material produced through the above embodiments has a measured volume resistivity of 4 Ω·cm and a melt flow index of 6.8 g / 10min.

[0042] In another embodiment of this application, during the mixing stage, 60 parts by weight of polyolefin elastomer POE (Engage 8180) and 30 parts by weight of ethylene-zinc methacrylate ionomer (Zn-EMAA) are premixed, and 3 parts by weight of carboxylated graphene microplates FGMP and 5 parts by weight of zinc oxide whiskers ZnOw are added simultaneously. The mixture is then mixed at 160°C for 5 minutes to obtain material one.

[0043] The material obtained above is added to a single-screw extrusion granulation equipment for extrusion granulation. The melt temperature is reduced by 20°C to avoid damage to the graphene structure, i.e., extrusion granulation is carried out at 170°C.

[0044] The resulting granules were kept at 80°C, and 0.5 parts by weight of BIBP were added. The mixture was then absorbed at 69-80°C for 2 hours.

[0045] In another embodiment of this application, during the mixing stage, 70 parts by weight of polyolefin elastomer POE (Engage 8180) and 40 parts by weight of ethylene-zinc methacrylate ionomer (Zn-EMAA) are premixed, and 8 parts by weight of carboxylated graphene microplates FGMP and 10 parts by weight of zinc oxide whiskers ZnOw are added simultaneously. The mixture is then mixed at 160°C for 5 minutes to obtain material one.

[0046] The material obtained above is added to a single-screw extrusion granulation equipment for extrusion granulation. The melt temperature is reduced by 20°C to avoid damage to the graphene structure, i.e., extrusion granulation is carried out at 170°C.

[0047] The resulting granules were kept at 80°C, and 0.5 parts by weight of BIBP were added. The mixture was then absorbed at 69-80°C for 2 hours.

[0048] The cable semi-conductive shielding material produced by the technical solution of this application is formed as follows.

[0049] index This invention (POE / Zn-EMAA-FGMP) Volume resistivity (Ω·cm) 1-10 Melt index (g / 10min) 5 (120℃ / 2.16kg) Tensile strength (MPa) 18.2 Resistance change after thermal aging (150℃×168h) +5% Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A method for preparing a cable semiconductive shielding material based on a polyolefin elastomer ionomer composite system, characterized in that: Includes the following steps: 1) During the mixing stage, POE and Zn-EMAA are premixed, and carboxylated graphene micro-flakes FGMP and zinc oxide whiskers are added simultaneously; POE / Zn-EMAA premix was obtained; 2) Single-screw extrusion granulation: The POE / Zn-EMAA premix is ​​granulated after the temperature is reduced by 20°C; 3) Keep the obtained granules at 60-80℃ and add a crosslinking agent for post-absorption.

2. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 1, characterized in that: In the mixing stage of step 1), the temperature is maintained at 160°C for 5 minutes; During single-screw extrusion granulation in step 2), the extrusion granulation temperature is 170℃; In step 3), the added crosslinking agent includes one or a mixture of two of DCP and BIBP.

3. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 1, characterized in that: The weight parts of POE are 60-70, Zn-EMAA are 30-40, FGMP are 3-8, zinc oxide whiskers are 5-10, and crosslinking agent is 0.

5.

4. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 1, characterized in that: The weight percentages of POE, Zn-EMAA, FGMP, zinc oxide whiskers, and crosslinking agent are 65, 35, 5, 8, and 0.5, respectively.

5. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 1, characterized in that: In step 3), the absorption time is 2 hours.

6. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 1, characterized in that: In step 2) During single-screw extrusion granulation, a cooling jacket is installed at the feed inlet of the extruder, and chilled water at 15-20℃ is introduced at a flow rate of 15L / min to pre-cool the POE / Zn-EMAA premix obtained in step 1), so that the temperature of the POE / Zn-EMAA premix drops to 15-20℃ when it enters the barrel of the extruder. Set the screw speed of the extruder to 40-50 r / min; the length-to-diameter ratio of a single screw to 20:1; The temperatures are set sequentially from the extruder inlet to the pelleting die as follows: Zone 1 feeding section temperature is set to 140℃, Zone 2 front section of compression section temperature is set to 155℃, Zone 3 rear section of compression section temperature is set to 165℃, Zone 4 metering section temperature is set to 170℃, and Zone 5 pelleting die temperature is set to 168℃.

7. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 1, characterized in that: In step 3), the crosslinking agent is mixed and stirred with white oil to prepare a crosslinking agent-white oil solution; Add the qualified granules after extrusion granulation in step 2) into the mixer, turn on the heating system, set the temperature to 50-70℃, the rotation speed to 4-6 r / min, and preheat for 30 minutes; during the preheating period, monitor the temperature of the granules in real time through the temperature sensor built into the mixer. When the temperature reaches the set value, stop heating and maintain a constant temperature. Turn on the high-pressure atomizing nozzle and spray the crosslinking agent white oil solution evenly onto the surface of the granules at a rate of 5 mL / min. The amount of crosslinking agent sprayed is 1-1.5% of the granule mass, corresponding to 5%-7.5% of the solution mass. The spraying time is 40-60 min. After the spraying is completed, immediately turn on the vacuum system to reduce the pressure inside the mixer to -0.08 to -0.1 MPa and maintain it for 30 minutes; Turn off the vacuum system, adjust the mixer speed to 10 r / min, turn on the heating system, maintain the temperature at 75℃, and carry out constant temperature stirring and absorption for 2 hours; At 1 hour and 1.5 hours of absorption, the vacuum system was turned on and evacuated for 10 minutes to remove the gas inside the pellets. After 2 hours of absorption, the heating system was turned off, the cooling jacket of the mixer was turned on, and circulating cooling water at 25°C was introduced to reduce the temperature of the pellets to room temperature (25°C) for 1 hour.

8. The method for preparing cable semiconductive shielding material based on polyolefin elastomer ionomer composite system according to claim 7, characterized in that: When the crosslinking agent is DCP, the crosslinking agent and white oil are mixed at a mass ratio of 1:5 and stirred at 300 r / min for 15 min to prepare a 20% crosslinking agent white oil solution. When the crosslinking agent is BIBP, the crosslinking agent is mixed with white oil and stirred at 300 r / min for 15 min to prepare a 15% crosslinking agent white oil solution.

9. A cable semiconductive shielding material based on a polyolefin elastomer ionomer composite system, characterized in that: Prepared using the preparation method according to any one of claims 1 to 4.

10. The cable semiconductive shielding material based on a polyolefin elastomer ionomer composite system according to claim 9, characterized in that: In Zn-EMAA, zinc ions complex with FGMP carboxyl groups to form an ionic-π bond double cross-linked conductive network; after cross-linking, POE and Zn-EMAA form an island structure.

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