A method for preparing and applying a prefabricated insulating connector

Abstract

This invention provides a method for preparing and applying a prefabricated insulating component joint. The method involves first preheating, degassing, and premixing the raw materials for later use; then casting the pretreated raw materials, followed by initial curing and demolding to obtain an initially cured prefabricated insulating component joint; finally, post-curing the prefabricated insulating component joint, followed by cooling to obtain the final prefabricated insulating component joint. The raw materials include bisphenol-type epoxy resin, an anhydride curing agent, and fillers; the minimum initial curing temperature is 117°C, and the maximum initial curing temperature is 135°C. This method simplifies existing manufacturing processes and reduces the risk of cracking in ultra-high voltage combined prefabricated insulating component joints during storage, transportation, and online operation. This invention also provides applications of this preparation method.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage prefabricated component technology, specifically relating to a method for preparing and applying a prefabricated insulating component joint. Background Technology

[0002] With increasing calls for environmental protection, the development of renewable and clean energy has become a hot topic in power development worldwide. Offshore wind power, island wind power, and solar power will be the future directions for power development in coastal areas. Since these energy sources are far from land and require transmission via submarine cables, high-voltage direct current (HVDC) submarine cable transmission is the optimal technological choice. ±160kV, ±200kV, and ±320kV projects are already in operation. In the near future, flexible DC transmission will play a crucial role in supplying power to remote areas, offshore power, urban grid capacity expansion and upgrading, new energy utilization, and improving power quality in distribution networks, driving a significant increase in demand for high-voltage and ultra-high-voltage DC cables and accessories. In recent years, with the development of power grids, high-voltage and ultra-high-voltage DC transmission has been developing rapidly. Under these conditions, ±525kV (±535kV) series DC cable accessories have broad application prospects and significant market and social benefits.

[0003] The ±525kV series prefabricated composite insulation joints are large in size, thick-walled, and involve numerous production processes and long production cycles. During molding, it is necessary to prevent the inherent brittleness and cracking of the anhydride-cured bisphenol A epoxy resin system used in existing electrical insulation castings. It is also crucial to overcome shrinkage cracking caused by inconsistent shrinkage rates and thicknesses between different materials within the product structure. Furthermore, it is essential to address the issues of asynchronous curing due to the large size of the product, long casting time, and inconsistent physicochemical properties of the internal materials. The molding process is exceptionally complex compared to conventional epoxy insulation components. Improper process control can significantly increase the risk of cracking during storage, transportation, and online operation of the ultra-high voltage prefabricated composite insulation joints. Simultaneously, the pass rate for ±525kV (±535kV) ultra-high voltage DC cable accessories remains relatively low.

[0004] Therefore, in order to further improve the competitiveness of products, it is necessary to further improve the product qualification rate, enhance product performance, and further optimize the product material mixing process and product molding process. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for preparing a prefabricated insulating component joint, which simplifies the existing preparation process and reduces the risk of cracking of ultra-high voltage combined prefabricated insulating component joints during storage, transportation, and online operation.

[0006] The present invention also provides an application of a prefabricated insulating component joint.

[0007] A first aspect of the present invention provides a method for preparing a prefabricated insulating component joint, comprising the following steps:

[0008] S1: After preheating, degassing and premixing the raw materials, set them aside for later use;

[0009] S2: After pouring the pre-treated raw materials from step S1, perform initial curing and demolding to obtain the pre-cured pre-insulated joint.

[0010] S3: The prefabricated insulating component joint obtained in step S2 is post-cured and cooled to obtain the prefabricated insulating component joint.

[0011] The raw materials for preparation include bisphenol-type epoxy resin, acid anhydride curing agent, and filler;

[0012] The minimum starting temperature for initial curing is 117°C, and the maximum starting temperature for post-curing is 135°C.

[0013] Based on the curing characteristics of epoxy resin, this invention proposes a preparation method to reduce the risk of cracking in ultra-high voltage combined prefabricated insulation component joints, and establishes a molding and curing model for ultra-high voltage combined prefabricated insulation component joints.

[0014] One technical solution of the present invention concerning a prefabricated insulating component joint has at least the following beneficial effects:

[0015] On the one hand, the higher the degree of curing of epoxy resin, the higher the Tg value of the material, which reduces the mobility of molecular chains at the same ambient temperature, resulting in lower material toughness. Lower ambient temperatures lead to higher modulus and lower elongation of the epoxy resin. When epoxy resin is subjected to high and low temperature cycling, the significant difference in shrinkage between the internal metal inserts and the material itself, coupled with a larger product volume, prevents the release of stress, leading to cracking. On the other hand, the faster the cooling rate after epoxy resin curing, the shorter the time available for molecular chain adjustment, increasing the likelihood of internal shrinkage stress. Therefore, while ensuring that the performance of the prefabricated insulation joint meets the requirements of high-voltage insulated cable accessories, adjusting the degree of curing of the prefabricated insulation joint (reflected in controlling the material's Tg range) and controlling the cooling rate of the cured samples and products can simultaneously ensure good crack resistance.

[0016] The preparation method of the present invention can control the glass transition temperature (Tg) range of the pre-made insulating component joint by adjusting the curing process parameters without changing the material formula, control the cooling rate of the sample and product after curing, construct a brand-new product curing process model, and reduce the risk of product cracking.

[0017] The preparation method of the present invention controls the glass transition temperature (Tg) range of the prefabricated insulation joint, which can not only ensure that the curing degree of the material meets the technical requirements, but also increase the movement ability of the molecular chains of the cured material, improve the toughness of the material, especially the anti-cracking performance of the material at low temperatures.

[0018] The preparation method of the present invention controls the cooling rate after the prefabricated insulation joint is cured, which can increase the adjustment time of the molecular chains during the cooling and shrinkage process of the material, enable the molecular chains to be fully arranged in the system, reduce the shrinkage stress of the material, and thus further improve the toughness of the material.

[0019] The preparation method of the present invention does not require changing the preparation raw materials. Therefore, it is beneficial to the arrangement of mass production.

[0020] The preparation method of the present invention has a process and parameters that are particularly suitable for electrical insulation casting materials such as bisphenol A epoxy resin / anhydride curing agent. Similar inventive concepts can be adapted to solve the problem of curing shrinkage cracking of thermosetting materials.

[0021] The preparation method of the present invention adopts a brand-new curing process model. For the sample pieces, the cracking ratio can be reduced from about 80% to 0. For the prefabricated insulation joint products, after 10 cycles of -40°C to 35°C, no cracking occurs, and the test results of relevant electrical performance tests are all qualified.

[0022] According to some embodiments of the present invention, the anhydride curing agent includes methyltetrahydrophthalic anhydride.

[0023] According to some embodiments of the present invention, the filler includes alumina.

[0024] According to some embodiments of the present invention, the filler includes electrical-grade α-alumina.

[0025] According to some embodiments of the present invention, the preparation raw materials include:

[0026] Bisphenol epoxy resin: 100 parts;

[0027] Anhydride curing agent: 35 parts to 40 parts;

[0028] Filler: 300 parts to 350 parts.

[0029] According to some embodiments of the present invention, the preparation raw materials include:

[0030] Bisphenol epoxy resin: 100 parts;

[0031] Anhydride curing agent: 38 parts to 40 parts;

[0032] Filler: 300 parts to 330 parts.

[0033] In step S1, the raw materials are preheated, degassed, and premixed before being set aside. Their functions include:

[0034] It can remove trace amounts of water and other small volatile molecules that may be present in the raw materials, preventing the formation of pores inside the product.

[0035] Premixing allows the resin and powder filler to be fully impregnated and mixed, preventing inconsistent performance due to uneven mixing.

[0036] It facilitates the control of the system viscosity and the filling of materials in the mold during casting.

[0037] The raw materials are preheated, degassed, and premixed. For bisphenol-type epoxy resin and fillers, the temperature is 130℃~135℃, the pressure is 2mbar~5mbar, and the time is 4h~6h. For anhydride-based curing agents, the temperature is 50℃~60℃, the pressure is 8mbar~12mbar, and the time is 4h~6h.

[0038] In step S2, the casting can be carried out using a fully automatic continuous flexible epoxy vacuum casting equipment.

[0039] After initial curing, the sample is basically formed and meets the requirements for demolding. The demolding operation is completed within the specified time after initial curing.

[0040] After demolding, the samples were post-cured within 10 minutes under different post-curing processes. The post-cured samples were then cooled to room temperature at different cooling rates for testing.

[0041] According to some embodiments of the present invention, the initial curing includes a first-stage initial curing and a second-stage initial curing.

[0042] According to some embodiments of the present invention, the initial curing temperature of the first stage is 117°C to 125°C.

[0043] According to some embodiments of the present invention, the initial curing time of the first stage is 540 min to 600 min.

[0044] The first stage of initial curing ensures that the material is able to flow and the entire system is thermally expanded (at this time, the molecular chains can still move). The molecular chains have sufficient time and space to rearrange, eliminating stress concentration points caused by insufficient rearrangement of molecular chains and preventing thermal stress cracking (internal stress cracking).

[0045] According to some embodiments of the present invention, the initial curing temperature of the second stage is 130°C to 135°C.

[0046] According to some embodiments of the present invention, the initial curing time of the second stage is 360 min to 420 min.

[0047] The second stage of initial curing ensures that the product has initially solidified and formed, possessing the mechanical strength required for demolding. Furthermore, while the molecular chains are no longer mobile at this stage, molecular chain segments (links) can still move locally, facilitating further rearrangement and adjustment of these segments (links) and further elimination of stress concentration points. This prevents volumetric stress cracking (external stress cracking) and thermal stress cracking (internal stress cracking).

[0048] According to some embodiments of the present invention, the post-curing temperature is 130°C to 135°C.

[0049] According to some embodiments of the present invention, the post-curing time is 420 min to 660 min.

[0050] Post-curing can, on the one hand, further improve the mechanical strength of the product, ensuring that the mechanical strength of the product ultimately meets the requirements for product use and preventing external stress cracking (volume stress cracking); on the other hand, it can also control the glass transition temperature (Tg) of the product.

[0051] According to some embodiments of the present invention, the cooling rate is 0.05℃ / min to 0.3℃ / min.

[0052] The cooling rate is controlled at 0.05℃ / min to 0.3℃ / min. This is to control the appropriate cooling rate and prevent the product from freezing due to rapid cooling, which would prevent the molecular chain segments (chain segments) in the microstructure from being fully arranged and adjusted, thus creating internal stress concentration points and causing thermal stress cracking.

[0053] According to some embodiments of the present invention, the Tg temperature range of the prefabricated insulating component joint is 104°C to 107°C.

[0054] According to some embodiments of the present invention, the Tg temperature range of the prefabricated insulating component joint is 105°C to 107°C.

[0055] Tg characterizes the temperature at which an amorphous polymer material transitions from a highly elastic state to a glassy state (or vice versa) under heating conditions. In the highly elastic state, molecular chain segments (links) can still move, and internal stress can be released through the movement of chain segments (links), so the product generally does not crack. In the glassy state, however, the movement of the entire molecular chain (segments, links) is frozen, and it cannot be released under the action of internal stress and / or external stress, thus the product is at risk of cracking. The Tg of the same material after curing reflects, to some extent, the toughness (or brittleness) of the material. If the Tg is too low, the product has good flexibility, but the product is not completely cured, and the mechanical strength is insufficient to support the external stress that it may bear, which may lead to volumetric stress cracking (external stress cracking); if the Tg is too high, the product has high rigidity and hardness, but poor flexibility. If the product is cooled too quickly during the molding process, it is very easy to generate internal stress concentration points and cause thermal stress cracking (internal stress cracking).

[0056] The preparation method of the present invention is mainly applicable to the manufacture of large-volume, long-length epoxy insulating parts (mainly prefabricated insulating part joints).

[0057] "Large volume" mainly refers to a volume greater than 200L.

[0058] "Large length" mainly refers to a side length greater than 1.3m.

[0059] A second aspect of the present invention provides a high-pressure and / or ultra-high-pressure preform, which is prepared by the aforementioned preparation method.

[0060] One of the technical solutions of the present invention concerning high-pressure and / or ultra-high-pressure precast components has at least the following beneficial effects:

[0061] The high-voltage and / or ultra-high-voltage prefabricated components of the present invention are prepared by the preparation method of the present invention, ensuring that the various performance characteristics of the prefabricated insulation component joint meet the requirements of high-voltage insulated cable accessories. By adjusting the curing degree of the prefabricated insulation component joint (reflected in controlling the Tg range of the material) and controlling the cooling rate of the sample and product after curing, the sample / product can simultaneously possess good crack resistance.

[0062] The high-voltage and / or ultra-high-voltage preforms of the present invention are prepared using a novel curing process model. After 10 cycles at -40℃ to 35℃, no cracking occurred, and the relevant electrical performance test results were all qualified.

[0063] According to some embodiments of the present invention, high-voltage prefabricated components refer to 110kV prefabricated components.

[0064] According to some embodiments of the present invention, ultra-high voltage prefabricated components refer to prefabricated components of 220kV to 330kV.

[0065] According to some embodiments of the present invention, UHV prefabricated components refer to prefabricated components with a voltage rating of ≥500kV. Attached Figure Description

[0066] Figure 1 These are schematic diagrams of the ultra-high voltage prefabricated insulating component joints in Examples 3 to 5. Detailed Implementation

[0067] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0068] In some embodiments of the present invention, a method for preparing a prefabricated insulating connector is provided, comprising the following steps:

[0069] S1: After preheating, degassing and premixing the raw materials, set them aside for later use;

[0070] S2: After pouring the pre-treated raw materials from step S1, perform initial curing and demolding to obtain the pre-cured pre-insulated joint.

[0071] S3: The prefabricated insulating component joint obtained in step S2 is post-cured and cooled to obtain the prefabricated insulating component joint of the present invention.

[0072] The raw materials for preparation include bisphenol-type epoxy resin, acid anhydride curing agents, and fillers;

[0073] The minimum initial curing temperature is 117℃, and the maximum initial curing temperature is 135℃.

[0074] Based on the curing characteristics of epoxy resin, this invention proposes a preparation method to reduce the risk of cracking in the joint of ultra-high voltage combined prefabricated insulation components, and establishes a molding and curing model for the joint of ultra-high voltage combined prefabricated insulation components.

[0075] It is understandable that, on the one hand, the higher the degree of curing of epoxy resin, the higher the Tg value of the material, and the less mobile the molecular chains are at the same ambient temperature, resulting in lower material toughness. The lower the ambient temperature, the higher the modulus and the lower the elongation of the epoxy resin. When epoxy resin is under high and low temperature cycling, due to the large difference in shrinkage rates between the internal metal inserts and the material itself, and the larger product volume, the stress generated between them cannot be released, leading to cracking. On the other hand, the faster the cooling rate after epoxy resin curing, the shorter the time available for molecular chain adjustment, and the greater the possibility of shrinkage stress generated within the material. Therefore, while ensuring that the performance of the prefabricated insulation joint meets the requirements of high-voltage insulated cable accessories, adjusting the degree of curing of the prefabricated insulation joint (reflected in controlling the material Tg range) and controlling the cooling rate of the sample and product after curing are crucial to ensure that the sample / product simultaneously possesses good crack resistance.

[0076] It can also be understood that the preparation method of the present invention can control the glass transition temperature (Tg) range of the pre-insulated component joint by adjusting the curing process parameters without changing the material formula, control the cooling rate of the sample and product after curing, construct a brand-new product curing process model, and reduce the risk of product cracking.

[0077] Furthermore, the preparation method of the present invention controls the glass transition temperature (Tg) range of the pre-insulated component joint, which can not only ensure that the degree of curing of the material meets the technical requirements, but also increase the mobility of the molecular chains of the cured material, improve the toughness of the material, especially the crack resistance of the material at low temperature.

[0078] Furthermore, the preparation method of the present invention controls the cooling rate after the pre-insulated joint has been cured, which can increase the adjustment time of the molecular chains during the cooling and shrinkage process of the material, so that the molecular chains are fully arranged in the system, reduce the shrinkage stress of the material, and thus further improve the toughness of the material.

[0079] It is understood that the preparation method of the present invention does not require changes to the raw materials, which is beneficial for large-scale production.

[0080] It can also be understood that the preparation method, process, and parameters of this invention are particularly suitable for electrical insulating castables such as bisphenol A type epoxy resin / anhydride curing agent. Similar inventive concepts can be adapted to solve the problem of curing shrinkage and cracking in thermosetting materials.

[0081] It should be noted that the preparation method of this invention adopts a completely new curing process model, which can reduce the cracking rate of the sample from about 80% to 0. For the pre-insulated connector product, no cracking occurred after 10 cycles of -40℃ to 35℃, and the relevant electrical performance test results were all qualified.

[0082] In some embodiments of the present invention, the anhydride curing agent includes methyltetrahydrophthalic anhydride.

[0083] In some embodiments of the present invention, the filler comprises alumina.

[0084] In some embodiments of the present invention, the filler comprises electrical grade α-alumina.

[0085] In some embodiments of the present invention, the raw materials for preparation include:

[0086] Bisphenol type epoxy resin: 100 parts;

[0087] Anhydride curing agent: 35 to 40 parts;

[0088] Filler: 300-350 parts.

[0089] In some embodiments of the present invention, the raw materials for preparation include:

[0090] Bisphenol type epoxy resin: 100 parts;

[0091] Anhydride curing agent: 38 to 40 parts;

[0092] Filler: 300-330 parts.

[0093] In step S1, the raw materials are preheated, degassed, and premixed before being set aside. Their functions include:

[0094] It can remove trace amounts of water and other small volatile molecules that may be present in the raw materials, preventing the formation of pores inside the product.

[0095] Premixing allows the resin and powder filler to be fully impregnated and mixed, preventing inconsistent performance due to uneven mixing.

[0096] It facilitates the control of the system viscosity and the filling of materials in the mold during casting.

[0097] The raw materials are preheated, degassed, and premixed. For bisphenol-type epoxy resin and fillers, the temperature is 130℃~135℃, the pressure is 2mbar~5mbar, and the time is 4h~6h. For anhydride-based curing agents, the temperature is 50℃~60℃, the pressure is 8mbar~12mbar, and the time is 4h~6h.

[0098] In step S2, the casting can be carried out using a fully automatic continuous flexible epoxy vacuum casting equipment.

[0099] After initial curing, the sample is basically formed and meets the requirements for demolding. The demolding operation is completed within the specified time after initial curing.

[0100] After demolding, the samples were post-cured within 10 minutes under different post-curing processes. The post-cured samples were then cooled to room temperature at different cooling rates for testing.

[0101] In some embodiments of the present invention, the initial curing includes a first-stage initial curing and a second-stage initial curing.

[0102] In some embodiments of the present invention, the initial curing temperature of the first stage is 117°C to 125°C.

[0103] In some embodiments of the present invention, the initial curing time of the first stage is 540 min to 600 min.

[0104] The first stage of initial curing ensures that the material is able to flow and the entire system is thermally expanded (at this time, the molecular chains can still move). The molecular chains have sufficient time and space to rearrange, eliminating stress concentration points caused by insufficient rearrangement of molecular chains and preventing thermal stress cracking (internal stress cracking).

[0105] In some embodiments of the present invention, the initial curing temperature of the second stage is 130°C to 135°C.

[0106] In some embodiments of the present invention, the initial curing time of the second stage is 360 min to 420 min.

[0107] The second stage of initial curing ensures that the product has initially solidified and formed, possessing the mechanical strength required for demolding. Furthermore, while the molecular chains are no longer mobile at this stage, molecular chain segments (links) can still move locally, facilitating further rearrangement and adjustment of these segments (links) and further elimination of stress concentration points. This prevents volumetric stress cracking (external stress cracking) and thermal stress cracking (internal stress cracking).

[0108] In some embodiments of the present invention, the post-curing temperature is 130°C to 135°C.

[0109] In some embodiments of the present invention, the post-curing time is 420 min to 660 min.

[0110] Post-curing can, on the one hand, further improve the mechanical strength of the product, ensuring that the mechanical strength of the product ultimately meets the requirements for product use and preventing external stress cracking (volume stress cracking); on the other hand, it can also control the glass transition temperature (Tg) of the product.

[0111] In some embodiments of the present invention, the cooling rate is 0.05°C / min to 0.3°C / min.

[0112] The cooling rate is controlled at 0.05℃ / min to 0.3℃ / min. This is to control the appropriate cooling rate and prevent the product from freezing due to rapid cooling, which would prevent the molecular chain segments (chain segments) in the microstructure from being fully arranged and adjusted, thus creating internal stress concentration points and causing thermal stress cracking.

[0113] In some embodiments of the present invention, the Tg temperature range of the prefabricated insulating component joint is 104°C to 107°C.

[0114] In some embodiments of the present invention, the Tg temperature range of the prefabricated insulating component joint is 105°C to 107°C.

[0115] Tg characterizes the temperature at which an amorphous polymer material transitions from a highly elastic state to a glassy state (or vice versa) under heating conditions. In the highly elastic state, molecular chain segments (links) can still move, and internal stress can be released through the movement of chain segments (links), so the product generally does not crack. In the glassy state, however, the movement of the entire molecular chain (segments, links) is frozen, and it cannot be released under the action of internal stress and / or external stress, thus the product is at risk of cracking. The Tg of the same material after curing reflects, to some extent, the toughness (or brittleness) of the material. If the Tg is too low, the product has good flexibility, but the product is not completely cured, and the mechanical strength is insufficient to support the external stress that it may bear, which may lead to volumetric stress cracking (external stress cracking); if the Tg is too high, the product has high rigidity and hardness, but poor flexibility. If the product is cooled too quickly during the molding process, it is very easy to generate internal stress concentration points and cause thermal stress cracking (internal stress cracking).

[0116] The preparation method of the present invention is mainly applicable to the manufacture of large-volume, long-length epoxy insulating parts (mainly prefabricated insulating part joints).

[0117] "Large volume" mainly refers to a volume greater than 200L.

[0118] "Large length" mainly refers to a side length greater than 1.3m.

[0119] In other embodiments of the present invention, a high-pressure and / or ultra-high-pressure preform is provided, which is prepared by the preparation method of the present invention.

[0120] It is understood that the high-voltage and / or ultra-high-voltage prefabricated parts of the present invention are prepared by the preparation method of the present invention, which ensures that the various performance characteristics of the prefabricated insulation joint meet the requirements of high-voltage insulated cable accessories. By adjusting the curing degree of the prefabricated insulation joint (reflected in controlling the Tg range of the material) and controlling the cooling rate of the sample and product after curing, the sample / product can simultaneously have good crack resistance.

[0121] It is also understood that the high-voltage and / or ultra-high-voltage preforms of the present invention are prepared using a novel curing process model. After 10 cycles at -40℃ to 35℃, no cracking occurred, and the relevant electrical performance test results were all qualified.

[0122] In some embodiments of the present invention, high-voltage prefabricated components refer to 110kV prefabricated components.

[0123] In some embodiments of the present invention, ultra-high voltage prefabricated components refer to prefabricated components of 220kV to 330kV.

[0124] In some embodiments of the present invention, ultra-high voltage prefabricated components refer to prefabricated components with a voltage rating of ≥500kV.

[0125] The technical solution of the present invention will be better understood below with reference to specific embodiments.

[0126] Example 1

[0127] In this embodiment, a sample was prepared that conforms to industry standards, has a diameter of 140 mm, and a stress angle coating thickness of 3 mm.

[0128] The preparation method includes the following steps:

[0129] S1: After preheating, degassing and premixing the raw materials, set them aside for later use;

[0130] S2: After pouring the pre-treated raw materials from step S1, perform initial curing and demolding to obtain the pre-cured pre-insulated joint.

[0131] S3: The prefabricated insulating component joint obtained in step S2 is post-cured and cooled to obtain the prefabricated insulating component joint of the present invention.

[0132] The raw materials for preparation are:

[0133] Bisphenolic epoxy resin (Hunsman CT5531): 100 parts;

[0134] Anhydride curing agent: methyltetrahydrophthalic anhydride: 38 parts;

[0135] Electrical grade α-alumina filler: 330 parts.

[0136] In step S1, the raw materials are preheated, degassed, and premixed for later use. Specifically, for bisphenol-type epoxy resin and fillers, the temperature is 130℃, the pressure is 3 mbar, and the time is 5 hours. For anhydride-based curing agents, the temperature is 60℃, the pressure is 10 mbar, and the time is 5 hours.

[0137] In step S2, the casting is carried out using a fully automatic continuous flexible epoxy vacuum casting equipment.

[0138] Initial curing includes the first stage of initial curing and the second stage of initial curing.

[0139] The initial curing temperature for the first stage is 117℃~125℃.

[0140] The initial curing time for the first stage is 540 min to 600 min.

[0141] The initial curing temperature for the second stage is 130℃~135℃.

[0142] The initial curing time for the second stage is 360 min to 420 min.

[0143] The demolded samples began post-curing within 10 minutes. The post-cured samples were then cooled to room temperature at different cooling rates for testing.

[0144] The post-curing temperature is 130℃~135℃.

[0145] The post-curing time is 420 min to 660 min.

[0146] The cooling rate is 0.05℃ / min to 0.3℃ / min.

[0147] The Tg temperature range of the prefabricated insulating component joint is 104℃~107℃.

[0148] Example 2

[0149] This embodiment prepared a sample, which differs from Example 1 in that the initial and post-curing parameters, cooling rate, and Tg temperature are different. Specific parameters are shown in Table 1.

[0150] Comparative Examples 1-6

[0151] Six samples were prepared for comparative examples 1 to 6. The differences between these samples and those of Example 1 are the initial and post-curing parameters, cooling rates, and Tg temperatures. Specific parameters are shown in Table 1.

[0152] The cracking rate of the samples prepared in Examples 1, 2 and Comparative Examples 1 to 6 was tested.

[0153] The testing method is as follows:

[0154] Each group of samples consists of 5 samples. They are first frozen at -40℃ for 48 hours and then observed for any cracking.

[0155] The number of cracks was counted, and then high and low temperature cycling was continued from -40℃ to 35℃. The heating / cooling period of the cycle was 4 hours, the isothermal period was 2 hours, and the total time of one cycle was 12 hours.

[0156] A total of 10 cycles (5 days);

[0157] Then observe again for any cracks and count the number of cracks.

[0158] The results are shown in Table 1.

[0159] Table 1. Process parameters and cracking rate of the samples.

[0160]

[0161]

[0162] Example 3

[0163] This embodiment describes the fabrication of an ultra-high voltage pre-insulated connector, with a structural reference. Figure 1 As shown, the length of the ultra-high voltage prefabricated insulating connector is 1480mm and the volume is approximately 203L.

[0164] The difference from Example 1 lies in the initial and post-curing parameters, cooling rate, and Tg temperature. See Table 2 for specific parameters.

[0165] Example 4

[0166] This embodiment describes the fabrication of an ultra-high voltage pre-insulated connector, with a structural reference. Figure 1 As shown, the length of the ultra-high voltage prefabricated insulating connector is 1480mm and the volume is approximately 203L.

[0167] The difference from Example 3 lies in the different initial and post-curing parameters, cooling rates, and Tg temperatures. See Table 2 for specific parameters.

[0168] Example 5

[0169] This embodiment describes the fabrication of an ultra-high voltage pre-insulated connector, with a structural reference. Figure 1 As shown, the length of the ultra-high voltage prefabricated insulating connector is 1480mm and the volume is approximately 203L.

[0170] The difference from Example 3 lies in the different initial and post-curing parameters, cooling rates, and Tg temperatures. See Table 2 for specific parameters.

[0171] Comparative examples 7 to 10

[0172] Four types of ultra-high voltage prefabricated insulating connectors were prepared in Comparative Examples 7 to 10. The differences between these and Example 3 are the initial and post-curing parameters, cooling rate, and Tg temperature. Specific parameters are shown in Table 2.

[0173] Table 2. Process parameters and cracking rate of prefabricated insulated joints for ultra-high voltage applications.

[0174]

[0175] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing a prefabricated insulating component joint, characterized in that, Includes the following steps: S1: After preheating, degassing and premixing the raw materials, set them aside for later use; S2: After pouring the pre-treated raw materials from step S1, perform initial curing and demolding to obtain the pre-cured pre-insulated joint. S3: The prefabricated insulating component joint obtained in step S2 is post-cured and cooled to obtain the prefabricated insulating component joint. The raw materials for preparation include bisphenol-type epoxy resin, acid anhydride curing agent, and filler; The minimum starting temperature for initial curing is 117°C, and the maximum starting temperature for post-curing is 135°C. The initial curing includes a first stage of initial curing and a second stage of initial curing. The temperature of the first stage of initial curing is 117℃~125℃ and the time of the first stage of initial curing is 540min~600min. The temperature of the second stage of initial curing is 130℃~135℃ and the time of the second stage of initial curing is 360min~420min. The post-curing temperature is 130℃~135℃, and the post-curing time is 420min~660min; The cooling rate is 0.05℃ / min to 0.3℃ / min.

2. A high-voltage precast component, characterized in that, The high-voltage preform is prepared by the preparation method described in claim 1, wherein the high-voltage preform refers to a 110kV preform.

3. A type of ultra-high voltage precast component, characterized in that, The ultra-high voltage preform is prepared by the preparation method described in claim 1, and the ultra-high voltage preform refers to a preform of 220kV~330kV.

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