Insulating material for EBA / PE blended cross-linked GIS cable terminal and preparation method of insulating material

Abstract

The invention relates to the technical field of polyethylene cables, and particularly discloses an EBAPE blended cross-linked insulating material for a GIS cable terminal, a preparation method of the EBAPE blended cross-linked insulating material and a high-voltage cable product based on the EBAPE blended cross-linked insulating material. The insulating material is prepared from EBA, PE, a silane coupling agent, a cross-linking agent, a cross-linking assistant, a catalyst and an antioxidant through a specific process. Wherein a blending system of EBA and PE is subjected to a crosslinking reaction under the grafting action of a silane coupling agent to form a stable three-dimensional network structure, collaborative optimization of electrical properties and mechanical properties of the material is achieved from the molecular level, and the problems that an existing PE blending and crosslinking type high-voltage cable is poor in electrical properties and mechanical properties, complex in preparation process and unfriendly to environment are solved.

Description

Technical Field

[0001] The present application relates to the technical field of polyethylene cables, and particularly relates to an insulating material for an EBA / PE blend cross-linked GIS cable terminal and a preparation method thereof. Background Art

[0002] In modern power transmission systems, high-voltage cables, as key carriers for power transmission, the performance of their insulating layers is directly related to the safety and stability of power grid operation. Currently, cross-linked polyethylene (XLPE) has become the mainstream material for the insulating layer of high-voltage cables (110 kV and above) due to its excellent electrical insulation performance, mechanical strength, and processing performance. Against the backdrop of the rapid development of smart grids, new energy power generation grid connection, and urban underground utility tunnel construction, high-voltage cables are facing severe application challenges. Ultra-high voltage power transmission scenarios require materials to have higher resistance to electric breakdown and partial discharge; laying in complex terrains places extremely high demands on flexibility and tear resistance; extreme environments such as high temperature and humidity, and high altitude require long-term heat resistance and aging resistance performance guarantees. However, as the mainstream insulating material, XLPE, due to its semi-crystalline polymer characteristics, has problems such as insufficient low-temperature toughness (brittle below -40°C), limited heat resistance grade (long-term use temperature around 105°C), and weak resistance to electrical aging under high-frequency voltage. At the same time, the preparation process of traditional silane-crosslinked XLPE also has drawbacks such as long production cycle, high energy consumption, and difficulty in controlling cross-linking uniformity.

[0003] Currently, the modification of PE-based insulating materials mainly focuses on blend modification and cross-linking process optimization, but both have obvious defects. In terms of blend modification, adding polar elastomers such as EVA can improve flexibility, but the dielectric properties decrease due to dipole loss, restricting its application in cables above 110 kV, and it is prone to phase separation with PE; non-polar elastomers have poor toughening effects and high costs. In the optimization of the cross-linking process, silane-crosslinked PE has problems such as long cross-linking time, high energy consumption, and weak resistance to electrical tree growth; although electron beam cross-linking can shorten the time, high-energy radiation is prone to cause molecular chain breakage, and protective additives need to be added, increasing the complexity of the formulation.

[0004] In summary, existing insulating materials have significant deficiencies in aspects such as the balance of mechanical-electrical properties, the coordination of heat resistance and processing efficiency, and environmental adaptability. Therefore, developing high-voltage cable insulating materials with excellent mechanical-electrical properties, high process efficiency, and environmental friendliness has become an urgent need for the development of the industry. Summary of the Invention

[0005] In view of this, the purpose of the present application is to provide an insulating material for EBA / PE blend cross-linked GIS cable terminals and a preparation method thereof, which are used to solve the problems of poor electrical and mechanical properties, cumbersome preparation process, and environmental unfriendliness of existing PE blend cross-linked high-voltage cables.

[0006] To achieve the above technical purpose, the present application provides an insulating material for EBA / PE blend cross-linked GIS cable terminals, including the following components in mass percentages:

[0007] PE 60% - 85%;

[0008] EBA 5% - 30%;

[0009] Silane coupling agent 1% - 2%;

[0010] Cross-linking agent 0.5% - 3%;

[0011] Cross-linking auxiliary agent 0.8% - 1.2%;

[0012] Catalyst 0.1 - 1%;

[0013] The balance is antioxidant.

[0014] Further, the cross-linking agent is selected from one of silane coupling agents and peroxides.

[0015] Further, the cross-linking auxiliary agent includes one or more of calcium stearate, magnesium stearate, and zinc stearate.

[0016] Further, the silane coupling agent includes one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, diethylaminomethyltriethoxysilane, dichloromethyltriethoxysilane, and vinyltrimethoxysilane.

[0017] Further, the peroxide includes one of dicumyl peroxide, bis(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and bis(2,4-dichlorobenzoyl)peroxide.

[0018] Further, the catalyst includes one or more of dibutyltin dilaurate, diethyltin dilaurate, dibutyltin oxide, zinc diethyldithiocarbamate, and stannous dioctyldithiocarbamate.

[0019] Furthermore, the antioxidant includes one or more of antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 1135, and antioxidant 3114.

[0020] The present application provides a method for preparing an insulating material for an EBA / PE blend cross-linked GIS cable terminal. The preparation is carried out using the insulating material for an EBA / PE blend cross-linked GIS cable terminal, and includes the following steps:

[0021] Step S1, premixing: uniformly mixing PE and EBA to obtain a premix.

[0022] Step S2, extrusion blending: feeding the premix into an extruder to melt it, adding a silane coupling agent, a cross-linking agent, a cross-linking aid, a catalyst, and an antioxidant, and stirring for a preset time to obtain the insulating material for an EBA / PE blend cross-linked GIS cable terminal.

[0023] The present application provides a method for manufacturing a high-voltage cable, including the following steps:

[0024] Step S1, melting the insulating material for an EBA / PE blend cross-linked GIS cable terminal to obtain a cable premix.

[0025] Step S2, extruding the cable premix to coat it outside the conductor to form a prefabricated cable with an insulating layer blank.

[0026] Step S3, placing the prefabricated cable in warm water for a preset time of cross-linking reaction to obtain a high-voltage cable.

[0027] Furthermore, the temperature of warm water cross-linking is 70~90°C, and the time of warm water cross-linking is 12~24 h.

[0028] In summary, the present invention provides an insulating material for an EBA / PE blend cross-linked GIS cable terminal, a high-voltage cable, and a method for manufacturing the same. The insulating material for an EBA / PE blend cross-linked GIS cable terminal is prepared from polyethylene (PE), ethylene-butyl acrylate copolymer (EBA), a silane coupling agent, a cross-linking agent, a cross-linking aid, a catalyst, and an antioxidant through a specific process. Among them, the blend system of EBA and PE forms a stable three-dimensional network structure through a cross-linking reaction under the grafting action of the silane coupling agent, realizing the synergistic optimization of the electrical properties and mechanical properties of the high-voltage cable insulating material at the molecular level. In addition, due to the catalytic effect of the ester group of EBA on the hydrolysis reaction of silane, the warm water cross-linking time of this material is shortened from 24~48 hours of traditional XLPE to 12~24 hours, significantly improving the production efficiency.

[0029] Compared with the prior art, the insulating material for EBA / PE blend cross-linked GIS cable terminals of the present invention realizes the dual optimization of electrical and mechanical properties, further simplifies the cross-linking process, and improves the production efficiency. Specific Embodiments

[0030] The technical solutions of the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. Based on the embodiments in the specification of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope claimed by the present application.

[0031] Among them, there are no special restrictions on the sources of all raw materials of the present invention, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0032] The embodiments of the present application provide an insulating material for EBA / PE blend cross-linked GIS cable terminals, comprising the following components in mass percentages:

[0033] PE 60% - 85%;

[0034] EBA 5% - 30%;

[0035] Silane coupling agent 1% - 2%;

[0036] Cross-linking agent 0.5% - 3%;

[0037] Cross-linking aid 0.8% - 1.2%;

[0038] Catalyst 0.1 - 1%;

[0039] The balance is antioxidant.

[0040] It should be noted that polyethylene (PE), as the base polymer, provides rigid support and insulation properties for the material. Ethylene-butyl acrylate copolymer (EBA, molecular weight 20,000 - 50,000) can be uniformly dispersed in the PE matrix due to the good compatibility between its non-polar ethylene main chain and PE. Moreover, the flexible butyl acrylate side chains in the EBA molecule fill the gaps in the PE crystal regions through physical entanglement, forming a unique "rigid-flexible combination" microstructure. After cross-linking, the PE crystal regions and the EBA amorphous regions form Si-O-Si covalent bonds through the hydrolysis cross-linking of the alkoxy groups of the silane, constructing a three-dimensional network structure with both rigidity and flexibility. At this time, the material maintains an elongation at break ≥ 300% at -50°C. This structure not only makes the dielectric constant (1 kHz) of the material ≤ 2.5 and tanδ ≤ 0.0005, which is better than that of the EVA / PE blend system, but also reduces the free volume inside the material and increases the breakdown field strength, enabling the breakdown field strength it can withstand to reach 35 - 40 kV / mm (25°C, power frequency). At the same time, the corona resistance life of the electron beam cross-linked sample prepared with this combination is 30% longer than that of traditional XLPE at high frequency (10 kHz), and it also retains the high insulation property of PE (volume resistivity ).

[0041] In some embodiments, the cross-linking agent is selected from one of silane coupling agents and peroxides.

[0042] In some embodiments, the cross-linking aid includes one or more of calcium stearate, magnesium stearate, and zinc stearate.

[0043] In some embodiments, the silane coupling agent includes one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, diethylaminomethyltriethoxysilane, dichloromethyltriethoxysilane, and vinyltrimethoxysilane.

[0044] In some embodiments, the peroxide includes one of dicumyl peroxide, bis(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and bis(2,4-dichlorobenzoyl)peroxide.

[0045] In some embodiments, the catalyst includes one or more of dibutyltin dilaurate, diethyltin dilaurate, dibutyltin oxide, zinc diethyldithiocarbamate, and stannous dioctyldithiocarbamate.

[0046] In some embodiments, the antioxidant includes one or more of antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 1135, and antioxidant 3114.

[0047] The embodiment of the present application provides a preparation method of an insulating material for an EBA / PE blend cross-linked GIS cable terminal, which is prepared by using the insulating material for an EBA / PE blend cross-linked GIS cable terminal, and includes the following steps:

[0048] Step S1, premixing: uniformly mixing PE and EBA to obtain a premix.

[0049] Step S2, extrusion blending: feeding the premix into an extruder to melt it, adding a silane coupling agent, a cross-linking agent, a cross-linking aid, a catalyst, and an antioxidant, and stirring for a preset time to obtain an insulating material for an EBA / PE blend cross-linked GIS cable terminal.

[0050] The embodiment of the present application provides a preparation method of a high-voltage cable, which includes the following steps:

[0051] Step S1, melting the insulating material for an EBA / PE blend cross-linked GIS cable terminal to obtain a cable premix.

[0052] Step S2, extruding the cable premix to coat it outside the conductor to form a prefabricated cable with an insulating layer blank.

[0053] Step S3, placing the prefabricated cable in warm water for cross-linking reaction for a preset time to obtain a high-voltage cable.

[0054] In some specific embodiments, the melting and extrusion temperature is 160~190°C; the temperature of warm water cross-linking is 70~90°C, the water flow rate is 5~10 L / min, and the warm water cross-linking time is 12~24 h.

[0055] It should be noted that from the perspective of rheology, the melt flow index (MFI, test conditions: 190 °C / 2.16 kg) of EBA and PE has good matching (the difference ≤ 20%), and this characteristic ensures the melt pressure stability (fluctuation range ≤ 0.5 MPa) of the blend system during the extrusion process. Based on this excellent rheological property, the insulation layer thickness tolerance of high-voltage cables can be accurately controlled within ±1%, significantly improving the dimensional accuracy and quality stability of the products. In terms of crosslinking kinetics, the ester groups in the molecular structure of EBA have a significant catalytic effect on the hydrolysis reaction of silane. Specifically, compared with traditional XLPE materials, the crosslinking reaction time of the system of the present invention is shortened by 50% (from 24 to 48 hours to 12 to 24 hours), and the crosslinking degree (gel content) is increased to 80 - 85% (traditional XLPE is 75 - 80%). At the same time, EBA plays a "molecular bridging" role between the insulation layer and the shielding layer in the cable: during co-extrusion, through physical entanglement and interfacial chemical reactions induced by the diffusion of silane crosslinking agent, the interfacial peel strength between the two layers of materials is increased by 40% (≥8 N / mm), effectively preventing the hidden danger of partial discharge caused by interlayer delamination; the introduction of flexible segments of EBA reduces the difference in thermal expansion coefficients between the insulation layer and the shielding layer to ≤5% (the difference in the traditional system ≥15%), significantly reducing the interfacial stress concentration phenomenon caused by inconsistent deformation. In addition, this material system can achieve synchronous molding of the insulation layer and the shielding layer under processing parameters (extrusion temperature of 160 - 190 °C, crosslinking with warm water at 75 °C for 18 hours), overcoming the efficiency bottleneck of segmented processing required for traditional multi-layer structures.

[0056] The applicant further provides the following specific examples for reference to describe the present invention. It should be noted that these examples are merely descriptive and do not limit the present invention in any way.

[0057] Example 1

[0058] This example provides an EBA / PE blend crosslinked insulating material for GIS cable terminals and a high-voltage cable, and its components and preparation steps are as follows:

[0059] The components and contents of the EBA / PE blend crosslinked insulating material for GIS cable terminals are shown in Table 1.

[0060] The preparation steps of the high-voltage cable are as follows:

[0061] This embodiment of the present application provides a method for preparing a high-voltage cable, including the following steps:

[0062] Step S1, put EBA and PE into a high-speed mixer according to the ratio in Table 1, and mix for 5 - 10 minutes at room temperature to obtain a premix;

[0063] Step S2: Convey the premix to an extruder, set the temperature of the melting section of the extruder at 160 - 190 °C to melt the material; sequentially add a silane coupling agent, a crosslinking agent, a crosslinking aid, a catalyst, and an antioxidant to the molten material, set the screw speed of the mixing section at 150 - 250 rpm, and stir for 3 - 5 minutes; maintain a vacuum degree of -0.08 MPa in the exhaust section to remove moisture and volatiles in the material; extrude and pelletize through the extrusion section to form an EBA / PE blend crosslinked insulating material for GIS cable terminations with a particle size of 2 - 4 mm for standby;

[0064] Step S3: Melt and extrude the EBA / PE blend crosslinked insulating material for GIS cable terminations, and coat it on the outside of the conductor to form a prefabricated cable with an insulating layer blank;

[0065] Step S4: Place the prefabricated cable in a hot water tank at 80 °C, control the water flow rate at 5 - 10 L / min, and perform warm water crosslinking treatment for 24 hours to obtain a high-voltage cable.

[0066] Comparative Example 1

[0067] Specific substance components, mass ratios, and preparation parameters can be seen in Table 1, and other parts are the same as those in Example 1.

[0068] Comparative Example 2

[0069] Specific substance components, mass ratios, and preparation parameters can be seen in Table 1, and other parts are the same as those in Example 1.

[0070] Comparative Example 3

[0071] Specific substance components, mass ratios, and preparation parameters can be seen in Table 1, and other parts are the same as those in Example 1.

[0072] Perform the following effect performance tests on the high-voltage cables prepared in the above examples and comparative examples: crosslinking efficiency (GB / T18474 - 2001), elongation at break (GB / T 1040.2 - 2006), breakdown field strength (GB / T 1408.1 - 2016), dielectric loss (GB / T3048.11 - 2007), interfacial peel strength (GB / T 2790 - 1995), and the test results are shown in Table 1.

[0073] Table 1. Composition, preparation parameters, and performance test data

[0074]

[0075] Based on the data in Table 1, the following conclusions can be drawn:

[0076] Example 1 shows significant advantages in various performance indicators. Its crosslinking efficiency (83%), breakdown field strength (38 kV / mm), and interfacial peel strength (8.2 N / mm) all reach the highest values, demonstrating excellent comprehensive performance. Comparative Example 1 (pure PE system) and Comparative Example 2 (pure EBA system) only use a single polymer, and their performance indicators are all lower than those of Example 1, indicating that a single polymer is difficult to meet the comprehensive performance requirements of high-voltage cable insulating materials, further verifying the necessity of PE / EBA blending in promoting interfacial bonding and crosslinking reactions.

[0077] Through the comparative analysis of Example 1 and Comparative Example 3, it is found that when replacing EBA with an equal amount of EVA, Example 1 shows significant advantages in terms of crosslinking efficiency (+11%), breakdown field strength (+8 kV / mm), interfacial peel strength (+2.7 N / mm), crosslinking time (24 h), etc.; at the same time, it is also superior to Comparative Example 3 in terms of elongation at break at -50 °C (+130%) and dielectric loss (reduced by 32%). This result shows that the combination of PE, EBA, and silane coupling agent has a significant synergistic effect in improving the material properties. Its mechanism may stem from the excellent non-polar compatibility between EBA and PE, as well as the strengthening effect of the silane coupling agent on the PE / EBA interpenetrating network structure. Compared with the traditional PE / EVA blending system, this combination can more effectively optimize the crosslinking efficiency, enhance the insulation performance and interfacial stability, providing an innovative path for improving the performance of high-voltage cable insulating materials.

[0078] The above are the preferred embodiments of this application and are not used to limit the present invention. Although this application has been described in detail with reference to the examples, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements for some of the technical features. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

1. An insulating material for an EBA / PE blended cross-linked GIS cable terminal, characterized in that, Components including the following mass percentages: PE 60% - 85%; EBA 5% - 30%; Silane coupling agent 1% - 2%; Crosslinking agent 0.5% - 3%; Crosslinking aid 0.8% - 1.2%; Catalyst 0.1 - 1%; The balance is antioxidant.

2. The insulating material for EBA / PE blend crosslinked GIS cable terminals according to claim 1, characterized in that, The crosslinking agent is selected from one of silane coupling agents and peroxides.

3. The insulating material for EBA / PE blend crosslinked GIS cable terminal according to claim 1, characterized in that: The crosslinking aid includes one or more of calcium stearate, magnesium stearate, and zinc stearate.

4. The insulating material for EBA / PE blend crosslinked GIS cable terminal according to any one of claims 1 and 3, characterized in that: The silane coupling agent includes one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, diethylaminomethyltriethoxysilane, dichloromethyltriethoxysilane, and vinyltrimethoxysilane.

5. The insulating material for EBA / PE blend crosslinked GIS cable terminal according to any one of claims 1 and 3, characterized in that: The peroxide includes one of dicumyl peroxide, bis(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and bis(2,4-dichlorobenzoyl)peroxide.

6. The insulating material for EBA / PE blend crosslinked GIS cable terminal according to claim 1, characterized in that: The catalyst includes one or more of dibutyltin dilaurate, diethyltin dilaurate, dibutyltin oxide, zinc diethyldithiocarbamate, and stannous dioctyldithiocarbamate.

7. The insulating material for EBA / PE blend crosslinked GIS cable terminal according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 1135, and antioxidant 3114.

8. A preparation method of an insulating material for an EBA / PE blend cross-linked GIS cable terminal, characterized in that, Prepared using the insulating material for EBA / PE blend crosslinked GIS cable terminal according to any one of claims 1 - 7, including the following steps: Step S1, premixing: Mix PE and EBA evenly to obtain a premix. Step S2, extrusion blending: Feed the premix into an extruder to melt, add the silane coupling agent, crosslinking agent, crosslinking aid, catalyst, and antioxidant, and stir for a preset time to obtain the insulating material for EBA / PE blend crosslinked GIS cable terminal.

9. A method for preparing a high-voltage cable, characterized in that, Including the following steps: Step S1, melt the insulating material for EBA / PE blend crosslinked GIS cable terminal according to any one of claims 1 - 7 to obtain a cable premix. Step S2, extrude the cable premix to coat it outside the conductor to form a prefabricated cable with an insulating layer blank. Step S3, place the prefabricated cable in warm water for crosslinking reaction for a preset time to obtain a high-voltage cable.

10. The preparation method of the high-voltage cable according to claim 9, wherein, The temperature of the warm water crosslinking is 70~90°C, and the time of the warm water crosslinking is 12~24 h.

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