A packaging composition that combines high hydrophobicity and easy permeability, its preparation method and application.

Abstract

This application relates to the field of sensor encapsulation, specifically disclosing an encapsulation composition with both high hydrophobicity and easy permeability, its preparation method, and its application. The raw materials used include epoxy resin, a curing agent, and a hydrophobic additive in a weight ratio of 1:1:(3-4). The epoxy resin includes bisphenol A type epoxy resin or bisphenol F type epoxy resin. The hydrophobic additive is prepared from quartz sand and a surface-modified paraffin oil emulsion in a weight ratio of 100:(0.99-4.75), with the quartz sand having a mesh size of 10-1500 mesh. The preparation method involves continuously dispersing the quartz sand while simultaneously spray-mixing the surface-modified paraffin oil emulsion with the quartz sand until the surface-modified paraffin oil emulsion is completely consumed, followed by drying to obtain the hydrophobic additive. The composition of this application can be used for encapsulating sensors, exhibiting both good hydrophobicity and permeability, ensuring good insulation reliability and initial discharge voltage for the sensor.

Description

Technical Field

[0001] This application relates to the technical field of sensor packaging, and in particular to a packaging composition that combines high hydrophobicity and easy permeability, as well as its preparation method and application. Background Technology

[0002] Epoxy resin is suitable for sensor encapsulation due to its low coefficient of thermal expansion (which can be optimized to match chip materials), high thermal conductivity (achieved through the addition of inorganic fillers), and excellent electrical insulation properties. In outdoor environments with high humidity, salt spray, dust, and pollution, the hydrophobicity of the encapsulation material determines the wettability of the insulating surface and the risk of surface discharge, making it a primary characteristic for ensuring the long-term reliable operation of current transformers. Hydrophobic surfaces prevent water droplets from spreading, allowing them to form isolated beads that carry away conductive contaminants through surface tension, significantly reducing leakage current and creepage probability. Conversely, hydrophilic surfaces easily form continuous water films, dissolving salts and acidic substances to form conductive films, triggering dry arcing, causing surface corrosion, increased leakage current, and even developing into arcing failures.

[0003] Meanwhile, the coil diameter of instrument transformers (especially high-voltage coils) is as low as 0.02-0.04mm. If the epoxy resin is not fully impregnated, micro-air gaps will remain between the turns. The dielectric constant of these air gaps is significantly lower than that of the epoxy resin, which will generate a distorted electric field under alternating high voltage, inducing partial discharge, arcing / breakdown between lines. If the epoxy resin is fully impregnated, the air gaps can be replaced with a continuous insulating phase, significantly improving withstand voltage and lifespan. Vacuum casting combined with low-viscosity resin can better expel air and reduce interface defects, thereby improving the initial discharge voltage and long-term insulation reliability. In environments such as engine compartments, coils are exposed to moisture, salt spray, and oil contamination. Good impregnation and interface bonding can reduce moisture intrusion and surface discharge channels, reducing insulation resistance decay and corrosion risk.

[0004] To meet the high hydrophobicity requirement, technicians add fumed silica to the resin to improve hydrophobicity. However, this significantly increases the product viscosity, which leads to reduced permeability. As mentioned earlier, epoxy resin needs to fully penetrate into the high-voltage coil to achieve long-term insulation reliability. Reduced permeability will greatly affect performance, leading to transformer breakdown, partial discharge problems, etc. Therefore, traditional resins cannot have both good hydrophobicity and permeability, limiting the wide application of epoxy resin in sensor packaging. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a packaging composition that combines high hydrophobicity and easy permeability, along with its preparation method and application.

[0006] In a first aspect, this application provides a packaging composition that combines high hydrophobicity and easy permeability, employing the following technical solution: the raw materials used include epoxy resin, curing agent and hydrophobic additive in a weight ratio of 1:1:(3-4), wherein the epoxy resin includes bisphenol A type epoxy resin or bisphenol F type epoxy resin, and the hydrophobic additive is prepared from quartz sand and surface-modified paraffin oil emulsion in a weight ratio of 100:(0.99-4.75), wherein the mesh size of the quartz sand is 10-1500 mesh.

[0007] Preferably, the quartz sand has a mesh size of 400-600, and the weight ratio of the quartz sand to the surface-modified paraffin oil emulsion is 100:(1-2).

[0008] By adopting the above technical solution, this application uses epoxy resin, curing agent and hydrophobic additive in a specific weight ratio, selects bisphenol A type or bisphenol F type epoxy resin, and prepares hydrophobic additives from quartz sand and surface-modified paraffin oil emulsion in a specific weight ratio, and the quartz sand mesh size is 10-1500 mesh, so that the encapsulation composition has both high hydrophobicity and easy permeability, which can meet the requirements of material hydrophobicity for sensor encapsulation in harsh environments such as outdoor high humidity, reduce leakage current and creepage probability, and at the same time can fully penetrate into the transformer coil, replace the air gap with a continuous insulating phase, improve withstand voltage and life, reduce water vapor intrusion and surface discharge channels, and reduce insulation resistance decay and corrosion risk.

[0009] Preferably, the curing agent comprises methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:(0.45-0.65).

[0010] Preferably, the molar ratio of methyltetrahydrophthalic anhydride to tetrahydrophthalic anhydride is 1:0.6.

[0011] By adopting the above technical solution, this application utilizes methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride, both of which are liquid or low-melting-point acid anhydrides, to form a low-viscosity homogeneous system when mixed with epoxy resin. The difference in molecular structure between the two acid anhydrides produces a steric hindrance effect after mixing, reducing intermolecular forces and thus lowering the overall viscosity of the system. The methyl group of methyltetrahydrophthalic anhydride and the ortho-position structure of tetrahydrophthalic anhydride may form a looser molecular arrangement when mixed, reducing internal friction. Therefore, it can effectively reduce the overall viscosity of the encapsulation composition, helping it to penetrate more smoothly into the high-voltage coil and achieve long-term insulation reliability.

[0012] This application also strictly controls the molar ratio of methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride. If the amount of methyltetrahydrophthalic anhydride is too high, it will lead to an excess of reactive sites, causing an exponential increase in the reaction rate, releasing a large amount of heat in a short time, and resulting in cracking of the cured product. If the amount of tetrahydrophthalic anhydride is too high, the epoxy resin molecules will not be able to fully cross-link, increasing voids and affecting the sealing effect. Secondly, this application provides a method for preparing the above-mentioned encapsulation composition that combines high hydrophobicity and easy permeability, comprising the following steps: S1. Quartz sand is continuously dispersed under the conditions of amplitude of 1-2.5mm and vibration frequency of 5-30Hz. At the same time, surface-modified paraffin oil emulsion is spray-mixed with quartz sand at a temperature of 90-100℃ until the surface-modified paraffin oil emulsion is consumed. Then, it is dried at a temperature of 70-80℃ to obtain a hydrophobic additive. S2. Heat the epoxy resin to 65-125℃, add the hydrophobic additive, stir evenly and use it as component A, and use the curing agent as component B. Store them separately to obtain the encapsulation composition.

[0013] By adopting the above technical solution, in step S1, the quartz sand is subjected to continuous dispersion treatment with specific amplitude and vibration frequency, and then spray-mixed with surface-modified paraffin oil emulsion at a specific temperature and dried. This allows the quartz sand and surface-modified paraffin oil emulsion to be fully mixed, resulting in a hydrophobic additive with good performance. In step S2, the epoxy resin is heated and then the hydrophobic additive is added and stirred evenly as component A, while the curing agent is stored separately as component B. This yields a composition for encapsulation that combines high hydrophobicity and easy permeability. This ensures that when the composition is used for sensor encapsulation, it can improve hydrophobicity to reduce leakage current and creepage probability, while ensuring good permeability to improve pressure resistance and lifespan.

[0014] Preferably, in S1, the spray droplet size of the surface-modified paraffin oil emulsion is 10-150 μm.

[0015] Preferably, in step S1, the spray mixing is performed in stages, specifically as follows: Quartz sand is continuously dispersed under vibration conditions of 2-2.5 mm amplitude and 20-30 Hz frequency. Simultaneously, surface-modified paraffin oil emulsion is spray-blended with quartz sand at 90-100℃, controlling the spray droplet size of the surface-modified paraffin oil emulsion to be 80-150 μm. When the surface-modified paraffin oil emulsion is more than half full, the temperature is kept constant, and the amplitude is adjusted to 1-1.5 mm, the vibration frequency to 5-10 Hz, and the spray droplet size to 10-50 μm, until the surface-modified paraffin oil emulsion is completely consumed. The mixture is then dried at 70-80℃ to obtain a hydrophobic additive.

[0016] Preferably, in the spray blending of S1, when the amount of surface-modified paraffin oil emulsion is less than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 100-120 μm, and when the amount of surface-modified paraffin oil emulsion is more than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 20-30 μm.

[0017] By adopting the above technical solution, this application performs stepwise spray blending in the preparation of the hydrophobic additive. In the initial stage, under conditions of larger amplitude, higher vibration frequency, and larger spray droplet size, the surface-modified paraffin oil emulsion and quartz sand can be initially and fully contacted and mixed, achieving a pre-wetting effect. In the later stage, adjusting to smaller amplitude, lower vibration frequency, and smaller spray droplet size allows the surface-modified paraffin oil emulsion to adhere more uniformly to the quartz sand. The resulting hydrophobic additive enables the encapsulation composition to possess both high hydrophobicity and easy permeability, avoiding the problem of reduced permeability due to increased hydrophobicity. This meets the sensor encapsulation requirements, improves the voltage withstand capability, lifespan, and insulation reliability of the encapsulated sensor, and reduces leakage current, creepage probability, insulation resistance attenuation, and corrosion risk. Furthermore, in the spray blending process of preparing the hydrophobic additive, this application further controls different spray droplet sizes based on the amount of surface-modified paraffin oil emulsion used, enabling better mixing of the quartz sand and the surface-modified paraffin oil emulsion.

[0018] Thirdly, this application provides an application of the above-mentioned encapsulation composition that combines high hydrophobicity and easy permeability, comprising the following steps: potting a sensor with the encapsulation composition, curing, then cooling, demolding, and obtaining an encapsulated sensor.

[0019] Preferably, the flow rate of the glue is 0.5-0.8 L / min, and when the glue is filled to 70-80% of the volume, it is left to stand for 20-25 minutes, and then the glue is filled to 100% of the volume.

[0020] By adopting the above technical solution, this application uses the encapsulation composition to encapsulate the sensor, and controls the flow rate of the potting compound and adopts an intermittent potting method, which allows the composition to penetrate and fill better, reduces internal defects, and improves the encapsulation effect and the long-term insulation reliability of the sensor.

[0021] In summary, this application has the following beneficial technical effects: 1. This application uses epoxy resin, curing agent and hydrophobic additive in a specific weight ratio, selects bisphenol A type or bisphenol F type epoxy resin, and prepares hydrophobic additives from quartz sand and surface modified paraffin oil emulsion in a specific weight ratio, and the quartz sand mesh is 10-1500 mesh, so that the encapsulation composition has both high hydrophobicity and easy permeability, which can meet the requirements of material hydrophobicity for sensor encapsulation in harsh environments such as outdoor high humidity, reduce leakage current and creepage probability, and at the same time can fully penetrate into the transformer coil, replace the air gap with a continuous insulating phase, improve withstand voltage and life, reduce water vapor intrusion and surface discharge channels, and reduce insulation resistance decay and corrosion risk; 2. In preparing the hydrophobic additive, this application performs spray blending in steps and further controls different spray droplet sizes according to the amount of surface-modified paraffin oil emulsion, which enables the quartz sand and surface-modified paraffin oil emulsion to mix better, so that the encapsulation composition has both high hydrophobicity and easy permeability. 3. This application uses the encapsulation composition to encapsulate the sensor, and controls the flow rate of the potting compound and adopts an intermittent potting method, which allows the composition to penetrate and fill better, reduce internal defects, improve the encapsulation effect and the long-term insulation reliability of the sensor. Detailed Implementation

[0022] Material source Unless otherwise specified, all raw materials used in this application are commercially available products, specifically: The epoxy resin is a bisphenol A type epoxy resin, purchased from Nantong Xingchen Synthetic Materials Co., Ltd., with an epoxy equivalent of 181-190 g / eq. The surface-modified paraffin oil emulsion was obtained by mixing paraffin oil emulsion with a solid content of 30% purchased from Hengshui Shengkang Chemical Co., Ltd. with 0.5wt% KH570 for 30 min. The quartz sand was purchased from Huzhou Jinpeng Electrical Materials Co., Ltd.

[0023] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0024] Example 1.1 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability includes the following steps: S1. Quartz sand is placed in a vibrating screen and continuously dispersed under the conditions of 1.75 mm amplitude and 15 Hz vibration frequency. At the same time, surface-modified paraffin oil emulsion with a weight ratio of 0.99:100 and quartz sand with a mesh size of 10 mesh are spray-blended at 100℃, and the droplet size of the surface-modified paraffin oil emulsion is controlled to be 70 μm until the surface-modified paraffin oil emulsion is consumed. Then, it is dried by hot air circulation at 80℃ for 30 min to obtain hydrophobic additive. S2. Heat 1 kg of epoxy resin to 125°C, add 4 kg of hydrophobic additive, stir evenly and use as component A. Use 1 kg of curing agent (methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.65) as component B. Store them separately to obtain the encapsulation composition.

[0025] Example 1.2 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability includes the following steps: S1. Quartz sand is placed in a vibrating screen and continuously dispersed under the conditions of 1.75 mm amplitude and 15 Hz vibration frequency. At the same time, surface-modified paraffin oil emulsion with a weight ratio of 4.75:100 and quartz sand with a mesh size of 1500 are spray-blended at 90℃, and the droplet size of the surface-modified paraffin oil emulsion is controlled to be 70 μm until the surface-modified paraffin oil emulsion is consumed. Then, it is dried by hot air circulation at 70℃ for 30 min to obtain hydrophobic additive. S2. Heat 1 kg of epoxy resin to 65°C, add 3 kg of hydrophobic additive, stir evenly and use as component A. Use 1 kg of curing agent (methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.65) as component B. Store them separately to obtain the encapsulation composition.

[0026] Example 2.1 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 1.1 in that the 10-mesh quartz sand in S1 is replaced with 400-mesh quartz sand, and the weight ratio of the surface-modified paraffin oil emulsion to the quartz sand is adjusted to 100:1. All other aspects are the same as in Example 1.1.

[0027] Example 2.2 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 1.1 in that the 10-mesh quartz sand in S1 is replaced with 600-mesh quartz sand, and the weight ratio of the surface-modified paraffin oil emulsion to the quartz sand is adjusted to 100:2. All other aspects are the same as in Example 1.1.

[0028] Example 3.1 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 2.1 in that the curing agent in S2 is replaced with methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.6, while the rest is the same as in Example 2.1.

[0029] Example 3.2 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 2.1 in that the curing agent in S2 is replaced with methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.55, while the rest is the same as in Example 2.1.

[0030] Example 3.3 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 2.1 in that the curing agent in S2 is replaced with methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.5, while the rest is the same as in Example 2.1.

[0031] Example 3.4 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 2.1 in that the curing agent in S2 is replaced with methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.45, while the rest is the same as in Example 2.1.

[0032] Example 3.5 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 2.1 in that the curing agent in S2 is replaced with methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.35, while the rest is the same as in Example 2.1.

[0033] Example 3.6 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 2.1 in that the curing agent in S2 is replaced with methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.7, while the rest is the same as in Example 2.1.

[0034] Example 4.1 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 1.1 in that the curing agent in S2 is replaced with a 2-methylimidazole curing agent, while the rest is the same as in Example 1.1.

[0035] Example 4.2 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 1.1 in that the curing agent in S2 is replaced with phenolic amine epoxy resin curing agent T-31, while the rest is the same as in Example 1.1.

[0036] Example 5.1 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 3.1 in that, in S1, spray blending is performed stepwise, specifically as follows: Quartz sand was placed in a vibrating screen and continuously dispersed under the conditions of an amplitude of 2.5 mm and a vibration frequency of 20 Hz. At the same time, a surface-modified paraffin oil emulsion with a weight ratio of 1:100 and quartz sand with a mesh size of 400 were spray-blended at a temperature of 100°C. The droplet size of the surface-modified paraffin oil emulsion was controlled to be 150 μm. When the amount of surface-modified paraffin oil emulsion was more than half, the temperature was kept constant, and the amplitude was adjusted to 1.5 mm, the vibration frequency to 5 Hz, and the droplet size to 50 μm until the surface-modified paraffin oil emulsion was consumed. Then, it was dried by hot air circulation at a temperature of 80°C for 30 min to obtain a hydrophobic additive. All other steps were the same as in Example 3.1.

[0037] Example 5.2 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 3.1 in that, in S1, spray blending is performed stepwise, specifically as follows: Quartz sand was placed in a vibrating screen and continuously dispersed under the conditions of 2 mm amplitude and 30 Hz vibration frequency. At the same time, a surface-modified paraffin oil emulsion with a weight ratio of 1:100 and 400 mesh quartz sand were spray-blended at 100°C. The droplet size of the surface-modified paraffin oil emulsion was controlled to be 80 μm. When the amount of surface-modified paraffin oil emulsion was more than half, the temperature was kept constant, and the amplitude was adjusted to 1 mm, the vibration frequency to 10 Hz, and the droplet size to 10 μm until the surface-modified paraffin oil emulsion was consumed. Then, it was dried by hot air circulation at 80°C for 30 min to obtain a hydrophobic additive. All other steps were the same as in Example 3.1.

[0038] Example 5.3 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 5.1 in that, in S1, when the amount of surface-modified paraffin oil emulsion is less than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 120 μm; when the amount of surface-modified paraffin oil emulsion is more than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 30 μm. All other aspects are the same as in Example 5.1.

[0039] Example 5.4 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 5.1 in that, in S1, when the amount of surface-modified paraffin oil emulsion is less than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 100 μm; when the amount of surface-modified paraffin oil emulsion is more than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 20 μm. All other aspects are the same as in Example 5.1.

[0040] Example 5.5 A method for preparing an encapsulation composition that combines high hydrophobicity and easy permeability differs from Example 5.1 in that, in S1, when the amount of surface-modified paraffin oil emulsion is less than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 110 μm; when the amount of surface-modified paraffin oil emulsion is more than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 25 μm. All other aspects are the same as in Example 5.1.

[0041] Comparative Example 1 1 kg of epoxy resin was heated to 125°C, and 3.96 kg of 10-mesh quartz sand and 0.04 kg of paraffin oil emulsion were added. After stirring evenly, it was used as component A. 1 kg of curing agent (methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.65) was used as component B. The two were stored separately to obtain the encapsulation composition.

[0042] Application Example 1 The application of an encapsulation composition that combines high hydrophobicity and easy permeability includes the following steps: The sensor was ultrasonically cleaned in isopropanol for 10 minutes to remove grease and particulate matter. A vacuum encapsulation device was used, with the sensor housing sealed to the encapsulation inlet and the encapsulation outlet connected to the vacuum system. The sensor was placed in the mold, ensuring accurate positioning of the sensitive element and leads. The encapsulation composition obtained in Example 1.1 was injected at a flow rate of 0.5 L / min in two stages. The first stage was filled to 80% volume, and the mixture was allowed to stand for 20 minutes to release local air bubbles. The second stage was used to fill the remaining space and cover the surface. The mixture was cured at 75℃ / 3h + 90℃ / 2h + 100℃ / 2h + 130℃ / 2-4h until demolding. The overflow was removed and the flash was sanded to obtain the encapsulated sensor.

[0043] Application Example 2 The application of an encapsulation composition that combines high hydrophobicity and easy permeability includes the following steps: The sensor was ultrasonically cleaned in isopropanol for 10 minutes to remove grease and particulate matter. A vacuum encapsulation device was used, with the sensor housing sealed to the encapsulation inlet and the encapsulation outlet connected to the vacuum system. The sensor was placed in the mold, ensuring accurate positioning of the sensitive element and leads. The encapsulation composition obtained in Example 1.2 was injected at a flow rate of 0.8 L / min in two stages. The first stage was filled to 70% volume, and allowed to stand for 25 minutes to release local air bubbles. The second stage was used to fill and cover the surface. The mixture was cured at 75℃ / 3h + 90℃ / 2h + 100℃ / 2h + 130℃ / 2-4h until demolding. The overflow was removed and the flash was sanded down to obtain the encapsulated sensor.

[0044] Application Example 3-17 An application of a packaging composition that combines high hydrophobicity and easy permeability differs from Application Example 1 in that the packaging composition prepared in Example 1.1 is replaced with the packaging compositions prepared in Examples 2.1-5.5, while the rest is the same as Application Example 1.

[0045] Comparative Application Example 1 The encapsulation composition prepared in Example 1.1 was replaced with the encapsulation composition prepared in Comparative Example 1, and all other aspects were the same as in Application Example 1.

[0046] Performance testing

[0047] According to GB / T 2794-2022, the viscosity of the encapsulation composition was determined, and according to IEC TS 62073, the surface hydrophobicity of the encapsulation composition after curing was determined.

[0048] Table 1 Data Record Table

[0049] Data Analysis: As can be seen from Table 1, the encapsulation compositions obtained in Examples 1.1-2.2 of this application have low viscosity and excellent surface hydrophobicity. It is evident that the encapsulation compositions of this application combine high hydrophobicity and easy permeability, which can meet the requirements of material hydrophobicity for sensor encapsulation in harsh environments such as outdoor high humidity, reduce leakage current and creepage probability, and at the same time, can fully penetrate into the transformer coil, replace the air gap with a continuous insulating phase, improve withstand voltage and lifespan, reduce water vapor intrusion and surface discharge channels, and reduce insulation resistance decay and corrosion risk.

[0050] In Examples 3.1-4.2, the components of the curing agent were adjusted in this application. The results showed that the encapsulation composition obtained in Example 3.1 had a lower viscosity. It can be seen that this application utilizes methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride, both of which are liquid or low-melting-point acid anhydrides, which can form a low-viscosity homogeneous system when mixed with epoxy resin. The difference in molecular structure between the two acid anhydrides produces a steric hindrance effect after mixing, reducing intermolecular forces and thus reducing the overall viscosity of the system. The methyl group of methyltetrahydrophthalic anhydride and the ortho-position structure of tetrahydrophthalic anhydride may form a looser molecular arrangement when mixed, reducing internal friction. Therefore, it can effectively reduce the overall viscosity of the encapsulation composition, helping it to penetrate more smoothly into the high-voltage coil and achieve long-term insulation reliability. This application also strictly controls the molar ratio of methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride. If the amount of methyltetrahydrophthalic anhydride is too large, it will lead to an excess of reactive sites, causing an exponential increase in the reaction rate, releasing a large amount of heat in a short time, and causing the cured product to crack. If the amount of tetrahydrophthalic anhydride is too large, it will cause the epoxy resin molecules to be unable to fully crosslink, resulting in more voids and affecting the sealing effect.

[0051] In Examples 5.1-5.5, this application adjusted the preparation process of the surface-modified paraffin oil emulsion. The results showed a significant reduction in viscosity. It can be seen that in preparing the hydrophobic additive, this application performs spray blending in stages. In the early stage, under conditions of larger amplitude, higher vibration frequency, and larger spray droplet size, the surface-modified paraffin oil emulsion and quartz sand can be initially and fully contacted and mixed, achieving a pre-wetting effect. In the later stage, the amplitude, lower vibration frequency, and smaller spray droplet size are adjusted to allow the surface-modified paraffin oil emulsion to adhere more evenly to the quartz sand. The final hydrophobic additive enables the encapsulation composition to have both high hydrophobicity and easy permeability, avoiding the problem of reduced permeability due to increased hydrophobicity. This meets the sensor encapsulation requirements, improves the voltage withstand, lifespan, insulation reliability, and other performance of the encapsulated sensor, and reduces leakage current, creepage probability, insulation resistance attenuation, and corrosion risk. Furthermore, in the process of preparing the hydrophobic additives by spray blending, this application further controls different spray droplet sizes according to the amount of surface-modified paraffin oil emulsion, which enables the quartz sand and the surface-modified paraffin oil emulsion to mix better.

[0052] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing an encapsulation composition possessing both high hydrophobicity and easy permeability, characterized in that, Includes the following steps: S1. Quartz sand is continuously dispersed under the conditions of amplitude of 2-2.5 mm and vibration frequency of 20-30 Hz. At the same time, surface-modified paraffin oil emulsion is spray-blended with quartz sand at a temperature of 90-100℃. The droplet size of the surface-modified paraffin oil emulsion is controlled to be 80-150 μm. When the amount of surface-modified paraffin oil emulsion is more than half, the temperature is kept constant, and the amplitude is adjusted to 1-1.5 mm, the vibration frequency to 5-10 Hz, and the droplet size to 10-50 μm until the surface-modified paraffin oil emulsion is consumed. The mixture is then dried at a temperature of 70-80℃ to obtain a hydrophobic additive. S2. Heat the epoxy resin to 65-125℃, add the hydrophobic additive, stir evenly and use it as component A, and use the curing agent as component B. Store them separately to obtain the encapsulation composition. The epoxy resin, curing agent and hydrophobic additive have a weight ratio of 1:1:(3-4). The epoxy resin includes bisphenol A type epoxy resin or bisphenol F type epoxy resin. The hydrophobic additive is prepared from quartz sand with a weight ratio of 100:(0.99-4.75) and surface-modified paraffin oil emulsion with a solid content of 30%. The mesh size of the quartz sand is 10-1500 mesh. The curing agent comprises methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride in a molar ratio of 1:0.

6.

2. The method for preparing an encapsulation composition with both high hydrophobicity and easy permeability according to claim 1, characterized in that, The quartz sand has a mesh size of 400-600, and the weight ratio of quartz sand to surface-modified paraffin oil emulsion is 100:(1-2).

3. The method for preparing an encapsulation composition with both high hydrophobicity and easy permeability according to claim 1, characterized in that, In the spray blending of S1, when the amount of surface-modified paraffin oil emulsion is less than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 100-120 μm; when the amount of surface-modified paraffin oil emulsion is more than half, the spray droplet size of the surface-modified paraffin oil emulsion is controlled to be 20-30 μm.

4. A packaging composition prepared by the method of preparing a packaging composition with both high hydrophobicity and easy permeability as described in any one of claims 1-3.

5. An application of a packaging composition that combines high hydrophobicity and easy permeability, characterized in that, Includes the following steps: The sensor is potted using the encapsulation composition of claim 4, cured, cooled, and demolded to obtain the encapsulated sensor.

6. The application of the encapsulation composition with both high hydrophobicity and easy permeability according to claim 5, characterized in that, The flow rate of the glue is 0.5-0.8 L / min. When the glue is filled to 70-80% volume, it is left to stand for 20-25 minutes, and then the glue is filled to 100% volume.

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