A layered synchronous injection molding production process for high-voltage cable accessories

Abstract

This application relates to the field of high-voltage cable technology and provides a layered synchronous injection molding production process for high-voltage cable accessories, including: S100, adding a first premix and a main vulcanizing agent to a functional base adhesive, and mixing to obtain a functional adhesive; S200, adding a second premix and a main vulcanizing agent to an insulating base adhesive, and mixing to obtain an insulating adhesive; S300, simultaneously injecting the functional adhesive and the insulating adhesive into a mold in layers, and after vulcanization treatment, cooling and demolding to obtain a high-voltage cable accessory; wherein, the vulcanization treatment includes a first stage vulcanization treatment and a second stage vulcanization treatment. This application adopts a layered synchronous injection molding method, which allows the functional adhesive and the insulating adhesive to directly contact each other when both are in an unvulcanized state, forming a continuous and tight interface under the action of injection pressure. This can avoid bonding obstacles caused by vulcanization, contamination, or deformation of the surface of the first-molded adhesive layer, and reduce interface gaps, micropores, and local unbonded areas.

Description

Technical Field

[0001] This application relates to the field of high-voltage cable technology, and in particular to a layered synchronous injection molding production process for high-voltage cable accessories. Background Technology

[0002] High-voltage cable accessories typically include a semi-conductive functional layer for improving electric field distribution and a main insulating layer covering the outside of the semi-conductive functional layer. To reduce interlayer assembly errors, improve product dimensional consistency, and shorten production cycles, existing technologies are increasingly adopting a layered synchronous injection molding method, in which uncured semi-conductive and insulating materials are injected separately into corresponding molding areas and co-cured within the mold.

[0003] Because the semi-conductive compound contains conductive fillers, while the main insulating compound needs to maintain high insulation performance, the two compounds differ in composition, viscosity, and vulcanization characteristics. During simultaneous injection molding, although the two compounds can form a direct contact interface, interlayer bonding mainly depends on the contact between the compounds and co-vulcanization of the main body. Insufficient cross-linking, micropores, or localized debonding can easily occur at the interface, affecting the insulation reliability of the cable accessories.

[0004] Existing technologies typically improve interfacial bonding by increasing vulcanization temperature, extending vulcanization time, or adding adhesive layers. However, increasing the overall vulcanization level makes it difficult to specifically enhance cross-interfacial connections, and adding adhesive layers adds processes and creates additional interfaces. Furthermore, if interfacial components migrate too deeply into the main insulation layer, it may affect insulation performance. Therefore, how to achieve stable interfacial bonding while maintaining the insulation performance of the main body is a problem that layered synchronous injection molding processes need to solve. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the existing technology, the purpose of this application is to provide a layered synchronous injection molding production process for high-voltage cable accessories.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: This application provides a layered synchronous injection molding production process for high-voltage cable accessories, including: S100: Add the first premix and the main vulcanizing agent to the functional base rubber, and mix to obtain the functional rubber compound; S200: Add the second premix and the main vulcanizing agent to the insulating base adhesive, and mix to obtain the insulating adhesive material; S300: Functional rubber and insulating rubber are injected into the mold in layers simultaneously. After vulcanization, the mold is cooled and demolded to obtain high-voltage cable accessories. The vulcanization process includes a first vulcanization process and a second vulcanization process.

[0007] In an optional implementation, S100 includes: S110. After mixing the silane-containing polysiloxane and the first carrier polysiloxane, the first dispersing filler is added and the mixture is continued to be mixed. After degassing, the first premix is ​​obtained. S120. The first silicone rubber matrix is ​​mixed with the processing aid and then subjected to a first mixing treatment. Then, reinforcing filler and functional filler are added in sequence for a second mixing treatment. After cooling, the functional base rubber is obtained. S130. Add the first premix to the functional base rubber and perform the first thin-pass treatment and the third mixing treatment in sequence. During the third mixing treatment, add the main vulcanizing agent to obtain the functional rubber compound.

[0008] In one optional embodiment, the temperature of the first mixing treatment is 50~80℃ and the time is 30~40min; and / or the temperature of the second mixing treatment is 135~150℃ and the time is 60~90min, with a vacuum degree of -0.085~-0.095MPa; and / or the temperature of the third mixing treatment is 20~35℃ and the time is 13~20min; and / or the first thin-pass treatment is performed 5~8 times.

[0009] In one optional embodiment, the functional rubber compound, by weight, comprises: 55-65 parts of a first silicone rubber matrix, 9-18 parts of reinforcing filler, 12-21 parts of functional filler, 2-5 parts of processing aid, 0.2-0.8 parts of silanol-containing polysiloxane, 0.08-0.4 parts of a first carrier polysiloxane, 0.03-0.16 parts of a first dispersing filler, and 0.45-1.3 parts of a main vulcanizing agent.

[0010] In an optional implementation, S200 includes: S210. After mixing the high-vinyl polysiloxane and the second carrier polysiloxane, the second dispersant filler, the reaction inhibitor and the platinum catalyst are added in sequence and the mixture is continued to be mixed. After degassing, the second premix is ​​obtained. S220. The second silicone rubber matrix is ​​mixed with the processing aid and then subjected to the fourth mixing treatment. Reinforcing filler is added and subjected to the fifth mixing treatment. After cooling, the insulating base adhesive is obtained. S230. Add a second premix to the insulating base adhesive and perform a second thin-pass treatment and a sixth mixing treatment in sequence. Add the main vulcanizing agent during the sixth mixing treatment to obtain the insulating adhesive.

[0011] In an optional embodiment, the platinum catalyst is added under a nitrogen atmosphere; and / or the fourth mixing treatment is performed at a temperature of 50-80°C for 30-40 min; and / or the fifth mixing treatment is performed at a temperature of 135-150°C for 60-90 min under a vacuum of -0.085 to -0.095 MPa; and / or the sixth mixing treatment is performed at a temperature of 20-35°C for 8-13 min; and / or the second thin-pass treatment is performed 3-5 times.

[0012] In one optional embodiment, the insulating compound, by weight, comprises: 60-70 parts of a second silicone rubber matrix, 16-26 parts of reinforcing filler, 2-5 parts of processing aid, 1.2-4.3 parts of high-vinyl polysiloxane, 1.8-5.7 parts of a second carrier polysiloxane, 0.24-0.87 parts of a second dispersing filler, 0.03-0.15 parts of platinum catalyst, 0.005-0.030 parts of reaction inhibitor, and 0.49-1.48 parts of main vulcanizing agent.

[0013] In one alternative embodiment, the main vulcanizing agent comprises a methyl vinyl silicone rubber carrier and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane.

[0014] In one alternative implementation, the temperature of the first vulcanization treatment is 90~115°C, the time is 5~10 min, and the pressure is 5~8 MPa.

[0015] In one optional implementation, the temperature of the second vulcanization treatment is 165~175°C, and the time is 20~35 min.

[0016] The beneficial effects of this application include at least the following: (1) This application adopts a layered synchronous injection molding method, which allows the functional rubber and the insulating rubber to come into direct contact when they are both in an uncured state. Under the action of injection pressure, a continuous and tight interface is formed, which can avoid the bonding obstacles caused by the curing, contamination or deformation of the surface of the first molded rubber layer, and reduce the interface gap, micropores and local unbonded areas. (2) In this application, the interfacial reaction components are respectively made into a first premix and a second premix, and then added to the corresponding base adhesive. This can improve the dispersion uniformity of a small amount of silane-containing components, high vinyl components and platinum catalyst in high viscosity silicone rubber, reduce local enrichment, precipitation and uneven catalytic activity, and make the reaction degree formed along the molding interface more consistent. (3) Through the first stage of vulcanization treatment, the silane-containing polysiloxane migrates to the adjacent area of ​​the interface in a limited manner, and undergoes hydrosilylation reaction with the high vinyl polysiloxane under the action of platinum catalysis, thereby forming a cross-interface chemical connection between the functional layer and the insulating layer, improving the interlayer peel strength and the interface stability after thermal cycling, and reducing the risk of interface debonding and crack propagation during long-term operation. (4) The main vulcanizing agent in the two rubber compounds is initiated to cross-link the bulk phase through the second vulcanization treatment. While obtaining the required mechanical strength, elasticity and dimensional stability, the interface reaction area formed by the first vulcanization is fixed, and the low molecular weight reaction components are restricted from continuing to migrate to the deep part of the main insulating layer. Therefore, it is possible to maintain a relatively clear semi-conductive-insulating electrical boundary while improving the interfacial bonding strength. Detailed Implementation

[0017] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.

[0018] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0019] High-voltage cable accessories typically consist of a semi-conductive functional layer and a main insulation layer. Current layered simultaneous injection molding processes usually inject uncured semi-conductive and insulating materials into corresponding areas, where they are co-cured within a mold. However, the two materials differ in composition, viscosity, and curing behavior. The interlayer bonding relies mainly on physical contact and co-curing of the main material, which can easily lead to problems such as insufficient interfacial bonding, micropores, or debonding.

[0020] Currently, interfacial bonding is mainly improved by increasing the vulcanization temperature, extending the vulcanization time, or adding an adhesive layer. However, the former is difficult to effectively form a stable cross-interfacial chemical bond, while the latter increases the processing steps and introduces an additional electrical transition layer. If conductive fillers or low-molecular-weight components migrate excessively into the main insulation layer, it may also affect the insulation performance and electric field distribution. In addition, the kinetics of interfacial reaction and main vulcanization are not entirely consistent. Direct high-temperature vulcanization can easily lead to insufficient interfacial reaction or excessive migration of reactive components.

[0021] This application provides a layered synchronous injection molding production process for high-voltage cable accessories. By setting a silane-containing polysiloxane in a semi-conductive functional adhesive and setting a high-vinyl polysiloxane, a platinum catalyst, and a reaction inhibitor in a main insulating adhesive, after synchronous injection molding, the silane-containing component is first allowed to migrate to the adjacent area of ​​the interface at a lower temperature and undergo hydrosilicification pre-crosslinking. Then, the temperature is raised to complete the peroxide main curing of the two adhesives, thereby forming a stable cross-interface connection and restricting the migration of reactive components to the depth of the main insulating layer.

[0022] This application provides a layered synchronous injection molding production process for high-voltage cable accessories, including: S100: Add the first premix and the main vulcanizing agent to the functional base rubber, and mix to obtain the functional rubber compound; S200: Add the second premix and the main vulcanizing agent to the insulating base adhesive, and mix to obtain the insulating adhesive material; S300: Functional rubber and insulating rubber are injected into the mold in layers simultaneously. After vulcanization, the mold is cooled and demolded to obtain high-voltage cable accessories. The vulcanization process includes a first vulcanization process and a second vulcanization process.

[0023] Preferably, steps S100 and S200 respectively prepare functional adhesive and insulating adhesive. The silanol-containing polysiloxane in the functional adhesive has a relatively high migration ability and can migrate short distances to the interface and the adjacent area of ​​the insulating adhesive after the two adhesives come into contact. The high vinyl polysiloxane in the insulating adhesive provides hydrosilylation reaction sites, the platinum catalyst is used to catalyze the interface reaction, and the reaction inhibitor is used to inhibit premature reaction at low temperature.

[0024] Specifically, S100 includes: S110. After mixing the silane-containing polysiloxane and the first carrier polysiloxane, the first dispersing filler is added and the mixture is continued to be mixed. After degassing, the first premix is ​​obtained. S120. The first silicone rubber matrix is ​​mixed with the processing aid and then subjected to a first mixing treatment. Then, reinforcing filler and functional filler are added in sequence for a second mixing treatment. After cooling, the functional base rubber is obtained. S130. Add the first premix to the functional base rubber and perform the first thin-pass treatment and the third mixing treatment in sequence. During the third mixing treatment, add the main vulcanizing agent to obtain the functional rubber compound.

[0025] Preferably, in step S110, the silane-containing polysiloxane, the first carrier polysiloxane, and the first dispersing filler are pre-prepared into a first premix, so that the low-viscosity, low-dosage silane-containing polysiloxane can be uniformly added to the high-viscosity functional base adhesive. If the silane-containing polysiloxane is directly added to the adhesive containing a large amount of reinforcing filler and functional filler, local enrichment, precipitation, or uneven concentration can easily occur, resulting in differences in the degree of reaction at different interface sites. Therefore, the silane-containing polysiloxane and the first carrier polysiloxane are first mixed at 25-30°C and 300-500 rpm for 10 min, and then the first dispersing filler is added in portions, and mixing is continued at 25-35°C and 500-800 rpm for 15-20 min. The first carrier polysiloxane can improve its compatibility with the first silicone rubber matrix, and the first dispersing filler can improve the viscosity and carrying capacity of the premix, so that the low-molecular-weight silane-containing components are distributed in a more uniform state. After the first premix is ​​mixed, degas it for 8 to 10 minutes at a temperature not higher than 40°C and a vacuum degree of -0.085 to -0.095 MPa. This can remove the air entrained during the mixing process and avoid excessively high temperatures from increasing the volatilization and flow of silane-containing polysiloxanes.

[0026] Preferably, in step S120, the first silicone rubber matrix and processing aids are first mixed, and then a first mixing treatment is performed at 50~80℃ for 30~40 minutes. Appropriate heating can reduce the mixing resistance of the silicone rubber matrix, ensure uniform distribution of the processing aids, and improve their wetting effect on the surface of subsequent fillers. After the first mixing treatment, reinforcing fillers and functional fillers are added sequentially. Both reinforcing fillers and functional fillers can be added in multiple stages. The reinforcing filler is first dispersed in the first silicone rubber matrix to form a relatively uniform mechanical reinforcing network; subsequently, conductive carbon black and other functional fillers are added to establish conductive pathways in the already formed continuous colloidal phase, which can reduce the mutual agglomeration and competitive wetting that occur when reinforcing fillers and functional fillers are added simultaneously. After adding reinforcing and functional fillers, a second mixing process is carried out at 135~150℃ and a vacuum of -0.085~-0.095MPa for 60~90 minutes. On the one hand, the high-temperature environment helps the processing aids to fully wet the filler surface, promoting the breakup and fine dispersion of agglomerates; on the other hand, the vacuum environment can effectively remove moisture, low-molecular-weight volatiles, and entrained air from the rubber compound. Since the functional rubber compound has a high proportion of conductive fillers, filler agglomeration or internal pores can easily lead to uneven resistivity of the semiconductive layer and distortion of the interfacial electric field. Therefore, this high-temperature vacuum mixing not only improves the uniformity of the rubber compound structure but also significantly reduces the risk of micropore formation at the interface after vulcanization.

[0027] Preferably, in step S130, a first premix is ​​added to the functional base rubber. The first premix is ​​added at 20-35°C and subjected to 5-8 first thin-pass treatments. Since the functional base rubber contains a large amount of reinforcing and functional fillers, the rubber compound has a high viscosity. A small amount of the first premix is ​​not easily dispersed uniformly by short-term mixing alone. During the thin-pass process, the rubber compound repeatedly passes through a small roller gap to form thin sheets. The first premix is ​​gradually stretched, divided, and distributed into the interior of the rubber compound, making the concentration of the silane-containing components in the functional rubber compound more uniform. After the thin-pass treatment, a third mixing treatment is performed at 20-35°C for 13-20 minutes. This inhibits premature decomposition of peroxides and reduces the possibility of scorching caused by shear heat, ensuring the functional rubber compound remains in a stable uncured state before simultaneous injection molding. The main vulcanizing agent is added during the third mixing treatment, which shortens the time it endures shear and temperature accumulation. This ensures uniform dispersion of the first premix and the main vulcanizing agent without causing a rise in rubber compound temperature or a decrease in operational stability. After the third mixing process, the material is degassed at a temperature not exceeding 35°C and a vacuum degree of -0.085 to -0.095 MPa to remove air re-entered during the thin-pass and mixing process, so that the resulting functional rubber compound has more stable fluidity and lower internal air content during injection molding.

[0028] Preferably, the functional rubber compound, by weight, comprises: 55-65 parts of a first silicone rubber matrix, 9-18 parts of reinforcing filler, 12-21 parts of functional filler, 2-5 parts of processing aid, 0.2-0.8 parts of silanol-containing polysiloxane, 0.08-0.4 parts of a first carrier polysiloxane, 0.03-0.16 parts of a first dispersing filler, and 0.45-1.3 parts of a main vulcanizing agent.

[0029] Furthermore, S200 includes: S210. After mixing the high-vinyl polysiloxane and the second carrier polysiloxane, the second dispersant filler, the reaction inhibitor and the platinum catalyst are added in sequence and the mixture is continued to be mixed. After degassing, the second premix is ​​obtained. S220. The second silicone rubber matrix is ​​mixed with the processing aid and then subjected to the fourth mixing treatment. Reinforcing filler is added and subjected to the fifth mixing treatment. After cooling, the insulating base adhesive is obtained. S230. Add a second premix to the insulating base adhesive and perform a second thin-pass treatment and a sixth mixing treatment in sequence. Add the main vulcanizing agent during the sixth mixing treatment to obtain the insulating adhesive.

[0030] Preferably, in step S210, the high-vinyl polysiloxane and the second carrier polysiloxane are first mixed, and then the second dispersant is added. If the high-vinyl polysiloxane and platinum catalyst are directly added to the insulating base adhesive, uneven local reaction sites and catalyst concentrations are likely to occur. However, the second carrier polysiloxane enables the high-vinyl component to be compatible with the second silicone rubber matrix, and the second dispersant increases the viscosity of the premix, allowing the high-vinyl component and the subsequently added platinum catalyst to remain relatively stably on the insulating adhesive side, reducing their tendency to migrate freely into the functional adhesive. Mixing the high-vinyl polysiloxane and the second carrier polysiloxane at 45~55℃ and 300~500 rpm, and then adding the second dispersant and continuing dispersion at 45~55℃ and 500~800 rpm, can appropriately reduce the viscosity of the high-vinyl polysiloxane and improve its mixing efficiency with the carrier polysiloxane and the dispersant. The mixture was then cooled to no higher than 25°C, and the reaction inhibitor and platinum catalyst were added sequentially. The reaction inhibitor was added first and evenly distributed, ensuring that the platinum catalyst was inhibited by low temperature upon entering the system, reducing the possibility of premature reaction of the second premix during preparation and subsequent mixing. The platinum catalyst was added under a nitrogen atmosphere, reducing the entry of moisture, dust, and other impurities from the air into the catalytic system, thus lowering the risk of contamination or fluctuation in platinum catalytic activity. Using milder mixing conditions of 20–25°C and 200–300 rpm ensured uniform catalyst dispersion while limiting shear heat generation, extending the workability of the insulating compound. The second premix was degassed at no higher than 25°C and a vacuum of -0.08 to -0.09 MPa, eliminating entrained gases during mixing and reducing the loss of reaction inhibitors caused by strong vacuum or high temperatures.

[0031] Preferably, in step S220, the second silicone rubber matrix and processing aid are first subjected to a fourth mixing treatment at 50-80°C for 30-40 minutes to form a uniform, processable continuous phase in the insulating matrix and improve the wetting efficiency of the subsequent reinforcing filler. Then, the reinforcing filler is added, and a fifth mixing treatment is performed at 135-150°C and a vacuum of -0.085 to -0.095 MPa for 60-90 minutes. This refines the agglomerated structure of the reinforcing filler and removes moisture, volatiles, and entrained air. The insulating layer is sensitive to moisture, micropores, and impurities. The fifth mixing treatment under the above conditions can reduce dielectric weaknesses within the insulating layer, lowering the possibility of localized electric field concentration and partial discharge.

[0032] Preferably, in step S230, after adding the second premix to the insulating base adhesive, a second thin-pass treatment is performed 3-5 times, followed by a sixth mixing treatment at 20-35°C for 8-13 minutes. The main vulcanizing agent is added during the sixth mixing treatment to ensure uniform dispersion in the insulating adhesive. The number of second thin-pass treatments is less than the first, and the sixth mixing treatment time is shorter than the third. This is because the second premix has already completed the pre-dispersion of the high-vinyl components, platinum catalyst, and reaction inhibitor; after adding it to the insulating base adhesive, only macroscopic uniform distribution needs to be achieved. Simultaneously, the platinum catalytic system is more sensitive to shear heat generation and temperature accumulation; reducing the number of thin-pass treatments and mixing time can reduce the risk of premature deactivation of reaction inhibitors, premature release of catalytic activity, and shortened working life of the adhesive. The main vulcanizing agent is added during the sixth mixing treatment to ensure uniform dispersion while avoiding unnecessary prolonged thin-pass treatment. After mixing, degassing is performed at a temperature not exceeding 30°C and a vacuum degree of -0.08 to -0.09 MPa to reduce the internal gas content of the insulating adhesive.

[0033] Preferably, the insulating compound, by weight, comprises: 60-70 parts of a second silicone rubber matrix, 16-26 parts of reinforcing filler, 2-5 parts of processing aid, 1.2-4.3 parts of high-vinyl polysiloxane, 1.8-5.7 parts of a second carrier polysiloxane, 0.24-0.87 parts of a second dispersing filler, 0.03-0.15 parts of platinum catalyst, 0.005-0.030 parts of reaction inhibitor, and 0.49-1.48 parts of main vulcanizing agent.

[0034] Preferably, a main vulcanizing agent is added to both types of rubber compounds, enabling the functional and insulating compounds to form complete bulk cross-linked networks under subsequent high-temperature conditions. The main vulcanizing agent includes a methyl vinyl silicone rubber carrier and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, which helps to bring the main vulcanization temperature zones of the two compounds closer together, reducing interfacial displacement, deformation, or stress unevenness caused by one side being rapidly vulcanized while the other side remains in a high-flow state.

[0035] Preferably, in step S300, after the functional and insulating rubber materials are prepared, they are simultaneously injected in layers. This allows the two rubber materials to form a direct contact interface while both are in an uncured state. Simultaneous injection molding avoids bonding obstacles caused by surface curing, contamination, or shrinkage of the first-formed rubber layer. Under injection pressure, the two rubber materials simultaneously fill their respective molding areas and wet each other, reducing interface wrinkles, air gaps, and unbonded areas. This provides continuous contact conditions for the subsequent migration of silane-containing components and hydrosilylation reactions. During simultaneous injection molding, the temperature of the barrel and conveyor channel is 20-30°C, the pressure is 10-18 MPa, and the time is 30-90 seconds. This prevents the peroxide and platinum catalyst system from reacting prematurely before entering the mold, ensuring that the two high-viscosity rubber materials fully fill their respective areas and form a tight bond at the designed interface.

[0036] Further, after injection molding, a vulcanization process is performed, which includes a first vulcanization process and a second vulcanization process. The temperature of the first vulcanization process is 90~115℃. Within this temperature range, the rubber compound has not yet rapidly formed a dense peroxide cross-linking network, and the molecular chains and low-molecular-weight silane-containing polysiloxanes still have a certain degree of mobility. The inhibitory effect of the reaction inhibitor gradually weakens, and the silane-containing components can migrate short distances to the interface region adjacent to the insulating rubber compound and undergo a preliminary hydrosilylation reaction with the high vinyl components. The time is 5~10 minutes, which can prevent the silane-containing components from migrating too deeply and prevent the interface reaction area from being too wide and affecting the electrical boundary of the main insulation layer. The pressure is 5~8MPa, which can maintain close contact between the two rubber compounds and reduce the interface voids formed by rubber shrinkage or gas expansion. The second stage of vulcanization is performed at a temperature of 165-175℃ for 20-35 minutes. This allows the main vulcanizing agent to decompose rapidly and initiate bulk cross-linking of the two rubber compounds. As the main cross-linking network gradually forms, the continued migration of silanol-containing polysiloxanes and other low-molecular-weight reactive components is restricted, and the pre-cross-linked interfacial region formed in the first stage of vulcanization is fixed in the contact adjacent area. Simultaneously, the incompletely reacted silanol-containing groups and vinyl groups at the interface continue to undergo hydrosilylation, further improving the cross-interfacial bonding.

[0037] Example 1

[0038] This embodiment provides a layered synchronous injection molding production process for high-voltage cable accessories, including the following steps: S110. Mix 0.4 parts of silane-containing polysiloxane and 0.2 parts of the first carrier polysiloxane at 28°C and 400 rpm for 10 min, then add 0.08 parts of the first dispersing filler, and continue mixing at 30°C and 650 rpm for 18 min. Degas for 9 min under the conditions of temperature not exceeding 40°C and vacuum degree of -0.09 MPa to obtain the first premix. S120. Mix 63.92 parts of the first silicone rubber matrix with 3.5 parts of processing aid, and perform a first mixing treatment at 65°C for 35 min. Add 14 parts of reinforcing filler in three portions, and then add 17 parts of functional filler in three portions, mixing for 10 min after each addition. After the addition is completed, perform a second mixing treatment at 145°C and a vacuum degree of -0.09 MPa for 75 min, and then cool to 32°C to obtain the functional base rubber. S130. Transfer the functional base rubber to a two-roll mill, control the roll temperature at 25°C, add the first premix, and perform six first thin pass treatments under a roll gap of 0.5~1mm, followed by a third mixing treatment. Add 0.9 parts of the main vulcanizing agent during the third mixing treatment. The temperature of the third mixing treatment is 28°C and the total time is 16min to obtain the functional rubber compound. S210. Mix 2.5 parts of high-vinyl polysiloxane and 3.75 parts of second-carrier polysiloxane at 50°C and 400 rpm for 25 min. Add 0.5 parts of second dispersion filler and continue mixing at 50°C and 650 rpm for 18 min. After cooling to 23°C, add 0.01 parts of reaction inhibitor and mix at 250 rpm for 5 min. Add 0.08 parts of platinum catalyst under nitrogen atmosphere and continue mixing at 23°C and 250 rpm for 10 min. Degas for 5 min under conditions of temperature not exceeding 25°C and vacuum degree of -0.085 MPa to obtain the second premix. S220. Mix 67.76 parts of the second silicone rubber matrix with 3.5 parts of processing aid, and perform a fourth mixing treatment at 65°C for 35 minutes. Add 21 parts of reinforcing filler in three portions, and perform a fifth mixing treatment at 145°C and a vacuum of -0.09MPa for 75 minutes. Then cool to 28°C to obtain the insulating base adhesive. S230. Transfer the insulating base adhesive to a two-roll mill, control the roller temperature at 22°C, add the second premix and perform four second thin pass treatments, then perform a sixth mixing treatment, and add 0.9 parts of the main vulcanizing agent during the sixth mixing treatment. The temperature of the sixth mixing treatment is 25°C and the total time is 10 minutes to obtain the insulating adhesive. S300: The functional rubber compound and the insulating rubber compound are loaded into separate injection units. The temperature of the barrel and the conveying channel is controlled at 25℃. The mixture is injected into the mold synchronously at an injection pressure of 14MPa for 60s. After injection, the first stage of vulcanization is carried out at 105℃ and 6.5MPa for 8 minutes. Then, the temperature is increased to 170℃ at a heating rate of 3℃ / min for the second stage of vulcanization for 28 minutes. After cooling to 55℃, the mixture is demolded to obtain the high-voltage cable accessory.

[0039] Example 2

[0040] This embodiment provides a layered synchronous injection molding production process for high-voltage cable accessories, including the following steps: S110. Mix 0.3 parts of silane-containing polysiloxane and 0.15 parts of the first carrier polysiloxane at 25°C and 300 rpm for 10 min, then add 0.06 parts of the first dispersing filler and continue mixing at 25°C and 500 rpm for 15 min; degas for 8 min at a temperature not higher than 40°C and a vacuum degree of -0.085 MPa to obtain the first premix. S120. Mix 64.29 parts of the first silicone rubber matrix with 3.50 parts of processing aid, and perform a first mixing treatment at 50°C for 30 minutes. Add 13.50 parts of reinforcing filler in three portions, and then add 17.5 parts of functional filler in three portions. Mix for 10 minutes after each addition. After the addition is completed, perform a second mixing treatment at 135°C and a vacuum of -0.085MPa for 60 minutes. Then cool to 30°C to obtain the functional base rubber. S130. Transfer the functional base rubber to a two-roll mill, control the roll temperature at 20°C, add the first premix, and perform five first thin pass treatments under a roll gap of 0.5~1mm, followed by a third mixing treatment. Add 0.7 parts of the main vulcanizing agent during the third mixing treatment. The temperature of the third mixing treatment is 22°C and the total time is 13min to obtain the functional rubber compound. S210. Mix 1.4 parts of high-vinyl polysiloxane and 2.10 parts of second-carrier polysiloxane at 45°C and 300 rpm for 20 min. Add 0.28 parts of second-dispersant filler and continue mixing at 45°C and 500 rpm for 15 min. After cooling to 20°C, add 0.01 parts of reaction inhibitor and mix at 200 rpm for 5 min. Add 0.04 parts of platinum catalyst under a nitrogen atmosphere and continue mixing at 20°C and 200 rpm for 10 min. Degas for 5 min at a temperature not exceeding 25°C and a vacuum degree of -0.08 MPa to obtain the second premix. S220. Mix 69.52 parts of the second silicone rubber matrix with 4 parts of processing aid, and perform a fourth mixing treatment at 50°C for 30 minutes. Add 22 parts of reinforcing filler in three portions, and perform a fifth mixing treatment at 135°C and a vacuum degree of -0.085MPa for 60 minutes. Then cool to 25°C to obtain the insulating base adhesive. S230. Transfer the insulating base adhesive to a two-roll mill, control the roller temperature at 20°C, add the second premix and perform three second thin pass treatments, then perform a sixth mixing treatment, and add 0.65 parts of the main vulcanizing agent during the sixth mixing treatment. The temperature of the sixth mixing treatment is 22°C and the total time is 8 minutes to obtain the insulating adhesive. S300: The functional rubber compound and the insulating rubber compound are loaded into separate injection units. The temperature of the barrel and the conveying channel is controlled at 23°C. The mixture is injected into the mold synchronously at an injection pressure of 12MPa for 50 seconds. After injection, the first stage of vulcanization is carried out at 90°C and 5MPa for 5 minutes. Then, the temperature is increased to 165°C at a heating rate of 2°C / min for the second stage of vulcanization for 20 minutes. After cooling to 55°C, the mixture is demolded to obtain the high-voltage cable accessory.

[0041] Example 3

[0042] This embodiment provides a layered synchronous injection molding production process for high-voltage cable accessories, including the following steps: S110. Mix 0.7 parts of silane-containing polysiloxane and 0.35 parts of the first carrier polysiloxane at 30°C and 500 rpm for 15 min, then add 0.14 parts of the first dispersing filler and continue mixing at 35°C and 800 rpm for 20 min; degas for 10 min at a temperature not higher than 40°C and a vacuum degree of -0.095 MPa to obtain the first premix. S120. Mix 56.11 parts of the first silicone rubber matrix with 4.5 parts of processing aid, and perform a first mixing treatment at 80°C for 40 minutes. Add 17.00 parts of reinforcing filler in three portions, and then add 20 parts of functional filler in three portions, mixing for 15 minutes after each addition. After the addition is completed, perform a second mixing treatment at 150°C and a vacuum degree of -0.095MPa for 90 minutes, and then cool to 35°C to obtain the functional base rubber. S130. Transfer the functional base rubber to a two-roll mill, control the roll temperature at 30°C, add the first premix, and perform the first thin pass treatment 8 times under the condition of roll gap of 0.5~1mm, then perform the third mixing treatment, and add 1.2 parts of the main vulcanizing agent during the third mixing treatment. The temperature of the third mixing treatment is 33°C and the total time is 20min to obtain the functional rubber compound. S210. Mix 3.5 parts of high-vinyl polysiloxane and 5.25 parts of second-carrier polysiloxane at 55°C and 500 rpm for 30 min. Add 0.7 parts of second-dispersant filler and continue mixing at 55°C and 800 rpm for 20 min. After cooling to 25°C, add 0.02 parts of reaction inhibitor and mix at 300 rpm for 5 min. Add 0.11 parts of platinum catalyst under nitrogen atmosphere and continue mixing at 25°C and 300 rpm for 10 min. Degas for 5 min under conditions of temperature not exceeding 25°C and vacuum degree of -0.090 MPa to obtain the second premix.

[0043] S220: Mix 62.22 parts of the second silicone rubber matrix with 4.00 parts of processing aid, and perform a fourth mixing treatment at 80°C for 40 min; add 23 parts of reinforcing filler in three batches, and perform a fifth mixing treatment at 150°C and a vacuum degree of -0.095MPa for 90 min, and then cool to 30°C to obtain the insulating base adhesive. S230. Transfer the insulating base adhesive to a two-roll mill, control the roll temperature at 25°C, add the second premix and perform five second thin pass treatments; continue with the sixth mixing treatment, and add 1.2 parts of the main vulcanizing agent during the sixth mixing treatment. The temperature of the sixth mixing treatment is 30°C and the total time is 13 minutes to obtain the insulating adhesive. S300: The functional rubber compound and the insulating rubber compound are loaded into separate injection units. The temperature of the barrel and the conveying channel is controlled at 28°C. The mixture is injected into the mold synchronously at an injection pressure of 16MPa for 70 seconds. After injection, the first stage of vulcanization is carried out at 115°C and 8MPa for 10 minutes. Then, the temperature is increased to 175°C at a heating rate of 4°C / min for the second stage of vulcanization for 35 minutes. After cooling to 55°C, the mixture is demolded to obtain the high-voltage cable accessory.

[0044] Comparative Example 1 The preparation method of this comparative example is basically the same as that of Example 1, except that: no interfacial hydrosilicification reaction system is set up, no silanol-containing polysiloxane is added to the functional rubber compound, and it is replaced by an equal mass of the first silicone rubber matrix; no high-vinyl polysiloxane, platinum catalyst and reaction inhibitor are added to the insulating rubber compound, and it is replaced by an equal mass of the second silicone rubber matrix. The first carrier polysiloxane, the second carrier polysiloxane, the first dispersion filler, the second dispersion filler and the remaining components remain unchanged. Both rubber compounds are co-cured with peroxide only by the main vulcanizing agent, and the vulcanization conditions are the same as those in Example 1.

[0045] Comparative Example 2 The formulation and preparation method of this comparative example are basically the same as those of Example 1, except that the positions of the first premix and the second premix are interchanged. The first premix, which consists of silanol-based polysiloxane, first carrier polysiloxane, and first dispersing filler, is added to the insulating base adhesive; the second premix, which consists of high vinyl polysiloxane, second carrier polysiloxane, second dispersing filler, reaction inhibitor, and platinum catalyst, is added to the functional base adhesive. The amount of the corresponding silicone rubber matrix is ​​adjusted so that the total mass of the functional adhesive and the insulating adhesive is kept at 100 parts. The remaining process conditions are the same as those of Example 1.

[0046] Comparative Example 3 The rubber compound formulation and simultaneous injection molding conditions in this comparative example are the same as those in Example 1. The difference is that after injection molding, the first stage of vulcanization is not performed. Instead, the mold is directly heated to 170°C and vulcanized at 6.5 MPa for 30 minutes, followed by cooling and demolding.

[0047] Comparative Example 4 The rubber compound formulation and preparation method of this comparative example are the same as those of Example 1. The difference is that the first stage of vulcanization is maintained at 105°C and 6.5MPa for 25 minutes, and then the temperature is increased to 170°C at 3°C / min for the second stage of vulcanization for 28 minutes.

[0048] Performance testing Initial peel strength test: Composite samples with 2mm thick functional adhesive layer and insulating adhesive layer were prepared by simultaneous injection molding using a flat double-layer mold. A 30mm wide polytetrafluoroethylene film was pre-embedded at one end of the sample interface to form the peel initiation end. After vulcanization, the sample was cut into strips with a width of 10mm and placed at 23±2℃ for 24h. A 180° peel test was performed at a speed of 100mm / min. The average peel force during the stable peel stage was recorded and divided by the sample width to obtain the interfacial peel strength.

[0049] Peel strength and retention rate test after thermal cycling: The composite sample was kept at -40℃ for 1 hour, then heated to 120℃ and kept for 1 hour. This was one thermal cycle. A total of 100 thermal cycles were carried out. After the thermal cycle was completed, the sample was placed at 23±2℃ for 24 hours. The peel strength of the interface was tested according to the above method, and the peel strength retention rate was calculated. Interface defect area ratio test: The sample is cut along the direction perpendicular to the interface between the functional adhesive layer and the insulating adhesive layer. After freeze cutting and polishing, the interface is observed under a 200x microscope. The ratio of the total area of ​​the interface micropores, cracks and debonding areas to the total area of ​​the observed interface area is calculated to obtain the interface defect area ratio. Interface reaction transition zone width test: Microscopic infrared spectroscopy scanning and micro-area modulus testing were performed along the direction perpendicular to the interface, with a scanning step of 10 μm, to determine the width of the continuous reaction zone transitioning from the functional adhesive main state to the insulating adhesive main state. Insulation side volume resistivity test: Cut an insulating adhesive sample 1 mm away from the interface between the functional adhesive layer and the insulating adhesive layer. The sample thickness is 1 mm. Adjust the temperature at 23±2℃ and relative humidity at 50±5% for 24 h. Apply a DC voltage of 500V for 60 s and measure the volume resistivity. Partial discharge initiation voltage test: Coaxial interface model samples with identical structure and dimensions were prepared for each group of adhesives, and the voltage was increased at a rate of 0.5 kV / s under a 50 Hz AC voltage. When the apparent discharge quantity reached or exceeded 10 pC for 10 consecutive seconds, the voltage at this time was recorded as the partial discharge initiation voltage; The test results are shown in Table 1.

[0050] Table 1

[0051] Examples 1-3 exhibited good initial peel strength, peel strength retention after thermal cycling, and interface defect area ratio, indicating that the separation of interfacial components, simultaneous injection molding, and segmented vulcanization can form a stable interfacial bond between the functional adhesive layer and the insulating adhesive layer. Comparative Example 1 showed significantly reduced initial peel strength and thermal cycling retention, increased interface defect area ratio, and higher volume resistivity on the insulation side. This was due to the absence of migration of hydroxyl-containing components, but poor interfacial adhesion and localized defects resulted in a significantly lower partial discharge initiation voltage compared to Examples 1-3. Comparative Example 2 showed less uniform interfacial reaction, a wider reaction transition zone, and decreased volume resistivity and partial discharge initiation voltage on the insulation side. This was because, after the two premixes were interchanged, the platinum catalyst was located in the functional adhesive containing conductive carbon black, and its catalytic activity was easily affected by adsorption on the filler surface and impurities. The hydroxyl-containing components, on the other hand, migrated from the insulating adhesive. The material migrates to the interface, leaving more low-molecular-weight reactive components on the insulation side. The peel strength, thermal cycling stability, and interface defect control of Comparative Example 3 are all lower than those of the Example. This is because the high-temperature vulcanization of the main peroxide vulcanization reaction is faster, and the bulk phase network of the rubber compound begins to form before the silane-containing components complete the necessary interface migration, which limits the cross-interface hydrosilylation reaction. The interface reaction transition zone of Comparative Example 4 is widened, and the volume resistivity and partial discharge initiation voltage of the insulation side decrease. This is because a higher peel strength is obtained after extending the first stage of vulcanization time, but the migration time of the silane-containing components before the formation of the main network is too long.

[0052] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A layered synchronous injection molding production process for high-voltage cable accessories, characterized in that, include: S100: Add the first premix and the main vulcanizing agent to the functional base rubber, and mix to obtain the functional rubber compound; S200: Add the second premix and the main vulcanizing agent to the insulating base adhesive, and mix to obtain the insulating adhesive material; S300. The functional rubber material and the insulating rubber material are injected into the mold in layers simultaneously. After vulcanization, the mold is cooled and demolded to obtain the high-voltage cable accessory. The vulcanization process includes a first vulcanization process and a second vulcanization process. S100 includes: S110. After mixing the silane-containing polysiloxane and the first carrier polysiloxane, the first dispersing filler is added and the mixture is continued to be mixed. After degassing, the first premix is ​​obtained. S120. The first silicone rubber matrix is ​​mixed with the processing aid and then subjected to a first mixing treatment. Then, reinforcing filler and functional filler are added in sequence for a second mixing treatment. After cooling, the functional base rubber is obtained. S130. The first premix is ​​added to the functional base rubber and subjected to a first thin-pass treatment and a third mixing treatment in sequence. The main vulcanizing agent is added during the third mixing treatment to obtain the functional rubber compound. S200 includes: S210. After mixing the high-vinyl polysiloxane and the second carrier polysiloxane, the second dispersant filler, the reaction inhibitor and the platinum catalyst are added in sequence and the mixture is continued to be mixed. After degassing, the second premix is ​​obtained. S220. The second silicone rubber matrix is ​​mixed with the processing aid and then subjected to a fourth mixing treatment. Reinforcing filler is added and subjected to a fifth mixing treatment. After cooling, the insulating base adhesive is obtained. S230. The second premix is ​​added to the insulating base adhesive and subjected to a second thin-pass treatment and a sixth mixing treatment in sequence. The main vulcanizing agent is added during the sixth mixing treatment to obtain the insulating adhesive material. The temperature of the first stage of vulcanization treatment is 90~115℃, the time is 5~10min, and the pressure is 5~8MPa; The temperature of the second stage of vulcanization treatment is 165~175℃, and the time is 20~35min.

2. The production process according to claim 1, characterized in that, The first mixing treatment is performed at a temperature of 50-80°C for a time of 30-40 minutes; and / or The second mixing treatment is carried out at a temperature of 135~150℃ for 60~90 min, with a vacuum degree of -0.085~-0.095 MPa; and / or The third mixing process is performed at a temperature of 20-35°C for 13-20 minutes; and / or The first thin-pass processing is performed 5 to 8 times.

3. The production process according to claim 1, characterized in that, The functional rubber compound, by weight, comprises: 55-65 parts of a first silicone rubber matrix, 9-18 parts of reinforcing filler, 12-21 parts of functional filler, 2-5 parts of processing aid, 0.2-0.8 parts of silanol-containing polysiloxane, 0.08-0.4 parts of a first carrier polysiloxane, 0.03-0.16 parts of a first dispersing filler, and 0.45-1.3 parts of a main vulcanizing agent.

4. The production process according to claim 1, characterized in that, The platinum catalyst was added under a nitrogen atmosphere; and / or The fourth mixing process is carried out at a temperature of 50-80°C for 30-40 minutes; and / or The fifth mixing process is carried out at a temperature of 135~150℃ for 60~90 min, with a vacuum degree of -0.085~-0.095 MPa; and / or The sixth mixing process is carried out at a temperature of 20-35°C for a time of 8-13 minutes; and / or The second thin-pass treatment is performed 3 to 5 times.

5. The production process according to claim 1, characterized in that, The insulating compound, by weight, comprises: 60-70 parts of a second silicone rubber matrix, 16-26 parts of reinforcing filler, 2-5 parts of processing aid, 1.2-4.3 parts of high-vinyl polysiloxane, 1.8-5.7 parts of a second carrier polysiloxane, 0.24-0.87 parts of a second dispersing filler, 0.03-0.15 parts of platinum catalyst, 0.005-0.030 parts of reaction inhibitor, and 0.49-1.48 parts of main vulcanizing agent.

6. The production process according to any one of claims 1 to 5, characterized in that, The main vulcanizing agent includes a methyl vinyl silicone rubber carrier and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane.

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