An aluminum electrolytic capacitor sealing cover plate suitable for various electrolyte wide temperature applications

Abstract

This invention discloses a sealing cover for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications. The sealing cover is manufactured using a substrate layer and a rubber sealing layer. The substrate layer is a POK substrate layer made primarily of polyketide polymers with added polyacrylic acid ester crosslinking agents. After injection molding, the POK substrate layer is irradiated with an electron beam or gamma ray to form a three-dimensional crosslinked network structure. The rubber sealing layer is composited with the POK substrate layer through a hot vulcanization process. This invention uses polyketide polymers as the substrate, fundamentally solving the problem of poor tolerance of traditional materials to highly polar organic electrolytes. Furthermore, through irradiation crosslinking modification, the material is transformed from a thermoplastic to a thermosetting network structure, achieving long-term stable operation over a wide temperature range. In particular, it maintains structural integrity and shows no softening or deformation even after continuous operation for over 3000 hours at 135°C.

Description

Technical Field

[0001] This invention relates to the field of electronic component packaging technology, specifically to a sealing cover plate for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications. Background Technology

[0002] Aluminum electrolytic capacitors, as indispensable passive components in power electronic systems, are widely used in new energy power generation, electric vehicles, 5G communication base stations, home appliances, and high-end industrial control equipment. Their reliability largely depends on the hermeticity of the packaging structure and the chemical and thermal stability of the materials, and the sealing cover is the core component for preventing leakage, blocking moisture, withstanding internal pressure, and ensuring long-term service safety.

[0003] Currently, most mainstream sealing covers are made of a phenolic resin-paperboard-rubber composite structure. However, this type of material has the following significant drawbacks in practical applications: Poor chemical resistance: Traditional materials have weak resistance to highly polar organic electrolytes such as γ-butyrolactone and acetonitrile, and are prone to swelling, delamination, aging or even cracking, leading to leakage and premature failure. Limited temperature resistance: Most materials can only work at temperatures below 105°C for extended periods, making it difficult to meet the requirement of continuous operation at 135°C under high-temperature conditions such as near the engine compartment. They are also prone to softening and deformation at high temperatures, resulting in loss of sealing performance. Heavy reliance on imports: Sealing covers have long relied on Japanese, South Korean and European and American manufacturers for supply, resulting in long delivery times and high costs, which seriously restricts the self-sufficiency and control of my country's high-end electronic components and the security of the industrial chain.

[0004] Therefore, there is an urgent need to develop a new sealing cover material system and manufacturing process to break through the existing technical bottlenecks and achieve a capacitor sealing cover with a wide temperature range, compatibility with multiple electrolytes, and high reliability. To this end, we propose an aluminum electrolytic capacitor sealing cover suitable for a wide temperature range of various electrolytes. Summary of the Invention

[0005] The purpose of this invention is to provide a sealing cover for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications, in order to solve the problems of poor chemical resistance and limited temperature resistance in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a sealing cover for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications, wherein the raw materials for manufacturing the sealing cover for aluminum electrolytic capacitors include a substrate layer and a rubber sealing layer; The substrate layer is a POK substrate layer made by mixing polyketone polymer as the main material with multifunctional polyacrylate crosslinking agent. After injection molding, the POK substrate layer is irradiated with electron beam or gamma ray to form a three-dimensional crosslinked network structure. The rubber sealing layer is composited with the POK substrate layer through a hot vulcanization process to form a double sealing structure.

[0007] Currently, most mainstream sealing covers are made of phenolic resin-paperboard-rubber composite structures. However, these materials have the following significant drawbacks in practical applications: poor chemical resistance: traditional materials have weak resistance to highly polar organic electrolytes such as γ-butyrolactone and acetonitrile, and are prone to swelling, delamination, aging, and even cracking, leading to leakage and premature failure; limited temperature resistance: most materials can only operate at temperatures below 105℃ for extended periods, making it difficult to meet the requirements of continuous operation at 135℃ under high-temperature conditions such as near engine compartments. They are prone to softening and deformation at high temperatures, resulting in loss of sealing performance; heavy reliance on imports: sealing covers have long relied on suppliers from Japan, South Korea, and Europe and the United States, resulting in long product delivery times and high costs, which seriously restricts the self-sufficiency and controllability of high-end electronic components and the security of the industrial chain in my country. This invention utilizes polyketide polymers as the base material, fundamentally solving the problem of poor resistance of traditional materials to highly polar organic electrolytes. During long-term immersion tests, it exhibits no swelling, delamination, or degradation, effectively preventing leakage and premature failure. Furthermore, through radiation crosslinking modification, the material is transformed from a thermoplastic to a thermosetting network structure, achieving long-term stable operation within a wide temperature range of 85℃-135℃. Notably, it maintains structural integrity and shows no softening or deformation even after continuous operation for over 3000 hours at 135℃, meeting automotive-grade application requirements. Secondly, the POK base material and rubber are firmly bonded through a hot vulcanization process, with an interfacial adhesion strength ≥3.0. With a strength of kN / m, this invention ensures the integrity of the sealing structure under complex operating conditions such as vibration, high pressure, and humid heat, preventing delamination and cracking. It also exhibits stable electrical performance. Furthermore, the invention employs an integrated process combining injection molding, irradiation crosslinking, and thermal vulcanization, a mature technology suitable for automated mass production. Finally, this invention is the first to apply POK material to the sealing cover of aluminum electrolytic capacitors, filling a domestic gap and changing the long-standing reliance on imports for this key component. This reduces the problems of long product delivery times and high costs, and enhances the self-reliance and controllability of my country's high-end electronic component industry chain.

[0008] As a further description of the above technical solution: The amount of the multifunctional acrylate crosslinking agent added is 5%-10% of the total mass of the POK substrate layer.

[0009] As a further description of the above technical solution: The irradiation is electron beam irradiation or gamma ray irradiation, with an irradiation dose of 50 kGy-120 kGy.

[0010] As a further description of the above technical solution: The irradiation process is carried out under the protection of nitrogen or an inert atmosphere.

[0011] As a further description of the above technical solution: The preferred irradiation dose is 80 kGy.

[0012] As a further description of the above technical solution: The interfacial bonding strength between the POK substrate layer and the rubber sealing layer is ≥3.0 kN / m.

[0013] As a further description of the above technical solution: The method for preparing a sealing cover plate for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications includes the following steps: Step 1: Blending and granulation: Polyketone polymers and multifunctional acrylate crosslinking agents are mixed in a certain proportion and prepared into modified POK particles by granulation machine; Step 2: Injection molding: Inject the modified POK granules into the mold and injection mold them into a POK substrate of a predetermined shape; Step 3: Irradiation crosslinking: The POK substrate of the predetermined shape is placed under the protection of nitrogen or inert atmosphere and irradiated with electron beam or gamma rays at a dose of 50kGy-120kGy to form a three-dimensional crosslinked network structure. Step 4: Surface treatment: Clean and dry the irradiated POK substrate, and uniformly coat it with hot vulcanizing adhesive; Step 5: Hot vulcanization: The POK substrate coated with adhesive is inserted into a rubber molding mold, rubber raw materials are added, and a vulcanization reaction is carried out under high temperature and high pressure conditions to make the rubber raw materials and the POK substrate coated with adhesive become one, thus obtaining the sealing cover plate of aluminum electrolytic capacitor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. First, this invention uses polyketide polymers as the base material, which fundamentally solves the problem of poor tolerance of traditional materials to highly polar organic electrolytes. In long-term immersion tests, there is no swelling, no delamination, and no degradation, effectively preventing leakage and early failure. Furthermore, through radiation crosslinking modification, the material is transformed from a thermoplastic to a thermosetting network structure, achieving long-term stable operation in a wide temperature range of 85℃-135℃. In particular, it can maintain structural integrity and no softening or deformation even after continuous operation at a high temperature of 135℃ for more than 3000 hours, meeting the requirements of automotive-grade applications. 2. Secondly, the POK substrate and rubber are firmly bonded through a hot vulcanization process, with an interfacial bonding strength ≥3.0 kN / m. Under complex working conditions such as vibration, high pressure, and humid heat, the sealing structure can be guaranteed to be intact, and there will be no delamination or cracking. The electrical performance is relatively stable. Furthermore, this invention adopts an integrated process of injection molding, irradiation crosslinking, and hot vulcanization, which is technically mature and suitable for automated mass production. 3. Finally, this invention is the first to apply POK material to the sealing cover of aluminum electrolytic capacitors, filling a domestic gap, changing the long-standing reliance on imports for this key component, reducing the problems of long product delivery time and high cost, and improving the self-reliance and controllability of my country's high-end electronic component industry chain. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the preparation method of the present invention; Figure 2 This is a graph showing the experimental data of the present invention operating at 85℃-135℃; Figure 3 This is a graph showing the durability test data of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: Please refer to Figures 1-3 The present invention provides a technical solution: an aluminum electrolytic capacitor sealing cover suitable for a wide range of electrolyte applications, wherein the raw materials for manufacturing the aluminum electrolytic capacitor sealing cover include a substrate layer and a rubber sealing layer; The substrate layer is a POK substrate layer made by mixing polyketone polymer as the main material with multifunctional polyacrylate crosslinking agent. After injection molding, the POK substrate layer is irradiated with electron beam or gamma ray to form a three-dimensional crosslinked network structure. The rubber sealing layer is composited with the POK substrate layer through a hot vulcanization process to form a double sealing structure.

[0018] The use of polyketone polymers as the base material fundamentally solves the problem of poor tolerance of traditional materials to highly polar organic electrolytes. Multifunctional polyacrylate crosslinking agents, under electron beam or gamma-ray irradiation, induce crosslinking reactions between POK molecular chains, forming a stable three-dimensional crosslinked network structure. This structure exhibits no swelling, delamination, or degradation during long-term immersion testing, effectively preventing leakage and premature failure. Furthermore, through irradiation crosslinking modification, the material is transformed from a thermoplastic to a thermosetting network structure, achieving long-term stable operation within a wide temperature range of 85℃-135℃. Notably, it maintains structural integrity and shows no softening or deformation even after continuous operation for over 3000 hours at 135℃, meeting automotive-grade application requirements. Secondly, the POK base material and rubber are firmly bonded through a hot vulcanization process, with an interfacial adhesion strength ≥3.0. kN / m, under complex working conditions such as vibration, high pressure, and humid heat, it can ensure the integrity of the sealing structure and will not degumming or cracking. The electrical performance is relatively stable. Furthermore, the present invention adopts an integrated process of injection molding, irradiation crosslinking and hot vulcanization, which is technically mature and suitable for automated mass production. A sealing cover, manufactured by combining a POK substrate layer (mainly composed of polyketone polymers with added multifunctional polyacrylate crosslinking agents) with a rubber sealing layer, can operate stably for extended periods within a temperature range of 85℃–135℃ and is resistant to ethylene glycol-based, γ-butyrolactone-based, and acetonitrile-based electrolytes. Figure 2 As shown: Example 2: The amount of the multifunctional acrylate crosslinking agent added is 5%-10% of the total mass of the POK substrate layer, and the irradiation is electron beam irradiation or gamma ray irradiation, with an irradiation dose of 50kGy-120kGy, preferably 80kGy.

[0019] The optimal dosage of multifunctional acrylate crosslinking agents can prevent insufficient crosslinking agents or low irradiation doses from causing POK molecular chains to fail to form a sufficiently dense three-dimensional network structure, thus preserving more thermoplastic characteristics. This prevents the material from softening, creeping, and deforming at 135°C, failing to meet the long-term thermal stability requirements for automotive-grade applications. Conversely, excessive multifunctional acrylate crosslinking agents or high irradiation doses can lead to an overly dense or even brittle internal network structure, reducing toughness and making the material prone to cracking under mechanical vibration or thermal shock. This also increases production costs and may cause degradation due to excessive free radical concentration. The optimal dosage range allows the material to maintain high toughness while achieving excellent thermosetting properties. In particular, the optimal dosage of 80 kGy produces a three-dimensional network structure, enabling the material to maintain structural integrity without softening or deformation after aging at 135°C for 3000 hours, with a capacity retention rate of ≥95%.

[0020] The irradiation process is carried out under the protection of nitrogen or an inert atmosphere.

[0021] During high-energy electron beam or gamma-ray irradiation, POK molecular chains break down, generating a large number of highly reactive free radicals. If this occurs in an oxygen-containing environment, these free radicals will rapidly react with oxygen, triggering oxidative degradation, leading to a decrease in material molecular weight, deterioration of mechanical properties, surface pulverization, or brittleness. Under nitrogen or inert gas protection, oxygen is isolated, forcing free radicals to undergo primarily intermolecular cross-linking reactions rather than oxidative breakage. This setup enables the formation of the desired dense three-dimensional network structure, resulting in excellent heat resistance and mechanical strength. Furthermore, the inert atmosphere effectively prevents this oxidative discoloration, ensuring that the manufactured sealing cover maintains good color and appearance quality, meeting the appearance standards of high-end electronic components. The oxygen-free environment improves the efficiency of free radicals in cross-linking reactions, allowing for higher gel content at the same irradiation dose, achieving the same performance indicators with a lower dose, or obtaining superior performance at the same dose.

[0022] The interfacial bonding strength between the POK substrate layer and the rubber sealing layer is ≥3.0kN / m. This bonding strength setting ensures that there is no delamination or separation under high temperature, high pressure and vibration conditions.

[0023] Example 3: The preparation method of the sealing cover plate of the aluminum electrolytic capacitor suitable for wide temperature range of various electrolytes includes the following steps: Step 1: Blending and granulation: Polyketone polymers and multifunctional acrylate crosslinking agents are mixed in a certain proportion and prepared into modified POK particles by granulation machine; Step 2: Injection molding: Inject the modified POK granules into the mold and injection mold them into a POK substrate of a predetermined shape; Step 3: Irradiation crosslinking: The POK substrate of the predetermined shape is placed under the protection of nitrogen or inert atmosphere and irradiated with electron beam or gamma rays at a dose of 50kGy-120kGy to form a three-dimensional crosslinked network structure. Step 4: Surface treatment: Clean and dry the irradiated POK substrate, and uniformly coat it with hot vulcanizing adhesive; Step 5: Hot vulcanization: The POK substrate coated with adhesive is inserted into a rubber molding mold, rubber raw materials are added, and a vulcanization reaction is carried out under high temperature and high pressure conditions to make the rubber raw materials and the POK substrate coated with adhesive become one, thus obtaining the sealing cover plate of aluminum electrolytic capacitor.

[0024] Firstly, blending, granulation, and injection molding ensure uniform dispersion of the crosslinking agent and precise substrate dimensions, laying the foundation for subsequent processing. Irradiation crosslinking under an inert atmosphere effectively inhibits oxidative degradation, transforming POK from a thermoplastic material into a dense thermosetting three-dimensional network. This endows the material with excellent heat resistance and electrolyte corrosion resistance for long-term operation at 135℃. Subsequently, surface treatment and hot vulcanization composite processes, using a specialized adhesive, achieve chemical bonding between the POK substrate and the rubber layer, with an interfacial bond strength ≥3.0 kN / m. This integrated structure of the plastic skeleton and rubber seal completely solves the problems of easy delamination and leakage in traditional covers, significantly improving the reliability of the product under high temperature, high pressure, and vibration conditions. The overall process is mature and controllable, suitable for automated large-scale production.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sealing cover plate for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications, characterized in that: The raw materials used to manufacture the aluminum electrolytic capacitor sealing cover include a substrate layer and a rubber sealing layer. The substrate layer is a POK substrate layer made by mixing polyketone polymer as the main material with multifunctional polyacrylate crosslinking agent. After injection molding, the POK substrate layer is irradiated with electron beam or gamma ray to form a three-dimensional crosslinked network structure. The rubber sealing layer is composited with the POK substrate layer through a hot vulcanization process.

2. The sealing cover plate for aluminum electrolytic capacitors suitable for a wide temperature range of various electrolytes according to claim 1, characterized in that: The amount of the multifunctional acrylate crosslinking agent added is 5%-10% of the total mass of the POK substrate layer.

3. The aluminum electrolytic capacitor sealing cover plate according to claim 2, suitable for wide-temperature applications with various electrolytes, is characterized in that: The irradiation is electron beam irradiation or gamma ray irradiation, with an irradiation dose of 50 kGy-120 kGy.

4. The aluminum electrolytic capacitor sealing cover plate according to claim 3, suitable for wide-temperature applications with various electrolytes, is characterized in that: The irradiation process is carried out under the protection of nitrogen or an inert atmosphere.

5. A sealing cover plate for aluminum electrolytic capacitors suitable for wide-temperature applications with various electrolytes according to claim 3, characterized in that: The preferred irradiation dose is 80 kGy.

6. The aluminum electrolytic capacitor sealing cover plate according to claim 3, suitable for wide-temperature applications with various electrolytes, characterized in that: The interfacial bonding strength between the POK substrate layer and the rubber sealing layer is ≥3.0 kN / m.

7. A method for preparing a sealing cover plate for an aluminum electrolytic capacitor suitable for wide-temperature applications with various electrolytes, as described in claims 1-6, characterized in that: The method for preparing a sealing cover plate for aluminum electrolytic capacitors suitable for a wide range of electrolyte applications includes the following steps: Step 1: Blending and granulation: Polyketone polymers and multifunctional acrylate crosslinking agents are mixed in a certain proportion and prepared into modified POK particles by granulation machine; Step 2: Injection molding: Inject the modified POK granules into the mold and injection mold them into a POK substrate of a predetermined shape; Step 3: Irradiation crosslinking: The POK substrate of the predetermined shape is placed under the protection of nitrogen or inert atmosphere and irradiated with electron beam or gamma rays at a dose of 50kGy-120kGy to form a three-dimensional crosslinked network structure. Step 4: Surface treatment: Clean and dry the irradiated POK substrate, and uniformly coat it with hot vulcanizing adhesive; Step 5: Hot vulcanization: The POK substrate coated with adhesive is inserted into a rubber molding mold, rubber raw materials are added, and a vulcanization reaction is carried out under high temperature and high pressure conditions to make the rubber raw materials and the POK substrate coated with adhesive become one, thus obtaining the sealing cover plate of aluminum electrolytic capacitor.

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