Oil-resistant rubber-clad laminate

Abstract

To provide an oil-resistant rubber-coated laminate that can prevent swelling of elastic components due to oil. [Solution] It is obtained by integrally molding an unvulcanized rubber sheet, multiple prepreg sheets, PP film, and nylon film as raw materials.

Description

Technical Field

[0001] The present invention relates to a sealing plate for aluminum electrolytic capacitors.

Background Art

[0002] With the global spread of the Internet and the advancement of digital technologies (5G, IoT, AI, etc.), the volume of data has increased sharply, and the number of data centers (hereinafter referred to as DCs) is also growing. Since a large amount of heat is generated by servers in DCs, air cooling using air conditioning equipment is common to prevent failures, but the cooling efficiency is low and the energy consumption for cooling is also high.

[0003] Accordingly, the demand for immersion cooling with high cooling efficiency is increasing. As a refrigerant for immersion cooling, fluorine-based inert liquids (for example, Fluorinert manufactured by 3M) are widely used, but there is a high possibility that their use will be reduced in the future due to PFAS regulations (3M will withdraw from the production of Fluorinert in 2025). In addition, since fluorine-based liquids are expensive, silicone-based refrigerant oils and hydrocarbon-based refrigerant oils can be cited as alternatives.

[0004] For the sealing plate used in aluminum electrolytic capacitors, a laminated plate is used which is formed by laminating a paper phenol board that functions as a hard support member to maintain the sealing strength of the case, and an elastic member such as a rubber material that functions as a sealing member on the paper phenol board. This sealing plate is produced by punching a laminated plate of about 1 square meter into a predetermined size, providing terminal fixing holes, and attaching terminals thereto. Further, for the aluminum electrolytic capacitor, a sealing process is performed in which the exterior case is caused to bite into the elastic member by curling the aluminum case, which is the same as in known manufacturing methods, with the sealing plate to which the terminals are attached.

[0005] That is, aluminum electrolytic capacitors are generally often used in a state where the elastic member is in contact with the outside air. When an aluminum electrolytic capacitor is immersion-cooled, if the refrigerant is a fluorine-based inert liquid, it is inert as the name implies and has little effect on the elastic member, so the capacitor can be used as it is without any special measures.

[0006] However, if the refrigerant oil is changed to the aforementioned alternative oil, especially if it is a hydrocarbon-based refrigerant oil, it will penetrate the elastic components of the aluminum electrolytic capacitor, causing them to swell. As a result, the aluminum electrolytic capacitor will not be able to perform as intended, and therefore the elastic components of the laminate used in the sealing plate must be changed to an oil-resistant specification. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-157012 [Patent Document 2] Japanese Patent Application Publication No. 11-268189 [Patent Document 3] Japanese Patent Publication No. 2003-301079 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] After manufacturing aluminum electrolytic capacitors, sealing the elastic components exposed to the outside air with resin or similar material can prevent swelling of the elastic components even if the refrigerant is changed to an alternative oil. However, this method requires sealing each aluminum electrolytic capacitor individually with resin, which has the disadvantage of being less productive than originally intended.

[0009] Therefore, in view of the above, the purpose of this disclosure is to provide an oil-resistant rubber-coated laminate that can prevent swelling of the elastic member due to oil without having to seal each aluminum electrolytic capacitor with resin, by imparting oil resistance to the elastic member of the laminate used in the sealing plate. [Means for solving the problem]

[0010] An oil-resistant rubber-clad laminate according to one aspect of the present disclosure is a sealing plate used in an aluminum electrolytic capacitor, characterized in that it is made from a rubber sheet, multiple prepregs, a PP film, and a nylon film, and the nylon film prevents the elastic member from swelling due to oil.

[0011] An oil-resistant rubber-clad laminate according to one aspect of this disclosure is obtained by integrally molding an unvulcanized rubber sheet, multiple prepregs, a PP film, and a nylon film by heating and pressing. By heating and pressing the above raw materials, an oil-resistant rubber-clad laminate consisting of a PP film, a phenolic resin laminate, a rubber sheet, and a nylon film is obtained.

[0012] The aforementioned unvulcanized rubber sheet mainly uses ethylene propylene rubber or butyl rubber, and has a Mooney viscosity (ML) that suppresses flow due to heating and pressurizing even in the unvulcanized state used during molding. 1+4 (100℃) is 85-160, and the curlastometer vulcanization rate index (t Δ80 A setting of 130°C for 15-30 minutes is preferable.

[0013] The aforementioned prepreg is made by impregnating a paper substrate, cloth, or glass cloth substrate with phenolic resin, and one or more types can be used, but it is not limited as long as it can be adhered to a rubber sheet or PP film. Furthermore, while similar effects can be obtained with any polyamide such as nylon 6 or nylon 6-6, nylon 6 is preferred as it is the most common. [Effects of the Invention]

[0014] According to this disclosure, it is possible to prevent swelling of the elastic member due to oil. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic cross-sectional view of an oil-resistant rubber-clad laminate according to an embodiment. [Figure 2]This is a diagram of a test pot used when confirming the oil retention rate of the oil-resistant rubber-clad laminate according to the embodiment.

Mode for Carrying Out the Invention

[0016] Hereinafter, the present disclosure will be described in detail based on the drawings showing its embodiment. Figure 1 is a cross-sectional view of the oil-resistant rubber-clad laminate 1 according to the embodiment.

[0017] The oil-resistant rubber-clad laminate 1 is used as a sealing plate for capacitors, and as shown in Figure 1, it consists of a nylon film 2, an unvulcanized rubber sheet 3, a phenolic resin laminate 4, and a polypropylene film (PP film) 5. The nylon film 2 has oil resistance.

[0018] Figure 2 is a diagram of a test pot used when confirming the oil retention rate of the oil-resistant rubber-clad laminate according to the embodiment.

[0019] The test pot 10 for confirming the oil retention rate is used to test the oil resistance of the nylon film 12. The nylon film 12 is crimped to the rubber carrier 11, and test oil 13 is added to the test pot 10. The test pot 10 has an oil container width 14 and a sample width 15.

Examples

[0020] (Preparation of Oil-Resistant Rubber-Clad Laminate) The prepreg used is obtained by impregnating kraft paper with resol-type phenolic resin varnish and semi-curing it by means such as heating and drying.

[0021] The prepregs were laminated so that the thickness after molding was 1.5 mm, a 1 mm thick unvulcanized EPDM rubber sheet and a 20 μm thick unstretched nylon 6 film were further laminated, a PP film was placed on the side of the prepreg layer that does not come into contact with the EPDM rubber sheet, the assembly was sandwiched between stainless steel plates, and subjected to heat and pressure molding (temperature 150°C, pressure 6 MPa) to produce a rubber-clad laminate. [Examples]

[0022] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding. A 1 mm thick unvulcanized EPDM rubber sheet and a 50 μm unstretched nylon 6 film were then laminated to create a rubber-clad laminate in the same manner as in Example 1. [Examples]

[0023] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding. A 1 mm thick unvulcanized EPDM rubber sheet and a 60 μm unstretched nylon 6 film were then laminated to create a rubber-clad laminate in the same manner as in Example 1. [Examples]

[0024] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding. A 1 mm thick unvulcanized EPDM rubber sheet and a 100 μm unstretched nylon 6 film were then laminated, and a rubber-clad laminate was prepared in the same manner as in Example 1. Comparative Example 1

[0025] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding. A 1 mm thick unvulcanized EPDM rubber sheet and a 50 μm PET film were then laminated, and a rubber-clad laminate was prepared in the same manner as in Example 1. Comparative Example 2

[0026] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding, and a 1 mm thick unvulcanized EPDM rubber sheet and a 50 μm OPP film were further laminated to produce a rubber-clad laminate in the same manner as in Example 1. Comparative Example 3

[0027] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding. A 1 mm thick vulcanized EPDM rubber sheet and a 100 μm unstretched nylon 6 film were then laminated, and a rubber-clad laminate was prepared in the same manner as in Example 1. Comparative Example 4

[0028] A prepreg similar to that in Example 1 was laminated to a thickness of 1.5 mm after molding, and a 1 mm thick unvulcanized EPDM rubber sheet was further laminated to produce a rubber-clad laminate in the same manner as in Example 1.

[0029] (evaluation) film peel strength The rubber-coated laminates obtained in Examples 1-4 and Comparative Examples 1-4 were cut into 20mm wide strips. The rubber film was held at a 180-degree angle to the adhesive surface using a jig, and approximately 50mm was peeled off continuously at a speed of approximately 50mm per minute. The average peeling force (N / 20mm) during this time was measured. The results are shown in Table 1.

[0030] [Table 1]

[0031] Oil resistance test 1 The rubber-clad laminates obtained in Example 2 and Comparative Examples 1 and 2 were processed to a diameter of approximately 13 mm, the phenolic resin laminate portion was removed using a polishing machine, and the rubber with various films attached was used as the sample for the oil resistance test. After drying this sample in a heat-circulating dryer at 50°C for 24 hours, the weight was measured to four decimal places and used as the initial weight of the sample.

[0032] Next, place 1.00g each of oil 1.IX TYPE H (manufactured by ENEOS Corporation), 2. High-pressure insulating oil K (manufactured by ENEOS Corporation), and 3. Barrel silicone fluid M-20E (manufactured by Matsumura Oil Co., Ltd.) into the test pot. Position the sample with the film side facing the oil and place it on top of the test pot. Close the lid of the test pot and use water pump pliers to compress the clamping rubber by approximately 0.25mm to seal it and prevent oil leakage.

[0033] The test pot was placed lid-side down and heated in a 125°C circulating dryer. Samples were removed at predetermined intervals, cooled at room temperature for 30 minutes, and the weight change was observed to calculate the swelling rate of the rubber. The results are shown in Table 2. In this test, a smaller weight change of the rubber is preferable as it suppresses swelling.

[0034] [Table 2]

[0035] Oil resistance test 2 The rubber-clad laminates obtained in Examples 1-3 and Comparative Examples 1-4 were processed to a diameter of approximately 13 mm, the phenolic resin laminate portion was removed using a polishing machine, and the rubber with various films attached was used as a sample for oil resistance testing.

[0036] Next, 1.00g each of oil 1.IX TYPE H (manufactured by ENEOS Corporation), 2. High-pressure insulating oil K (manufactured by ENEOS Corporation), and 3. Barrel silicone fluid M-20E (manufactured by Matsumura Oil Co., Ltd.) are placed in the test pot. The film side of the sample is placed on the oil side and then placed on top of the test pot. The lid of the test pot is closed, and the clamping rubber is compressed by approximately 0.25mm using water pump pliers to seal it so that no oil leaks out. The total weight of the test pot is then measured.

[0037] The test pots were heated in a 125°C heat-circulating dryer with the lids facing downwards. The test pots were then cooled at room temperature for 30 minutes at predetermined intervals, and the weight change was observed. The oil retention rate was calculated from the initial weight. The results are shown in Tables 3-4 (1. Oil retention rate of IX TYPE H over time), 5-6 (2. Oil retention rate of high-pressure insulating oil K over time), and 7 (3. Oil retention rate of barrel silicone fluid M-20E over time).

[0038] [Table 3]

[0039] [Table 4]

[0040] [Table 5]

[0041] [Table 6]

[0042] [Table 7]

[0043] Based on the peel strength and oil resistance tests described above, nylon 6 was determined to be the optimal film for oil resistance. Oil resistance test 1 was conducted to select the type of film to be applied to the rubber surface, and oil resistance test 2 was conducted to select the thickness of the film to be used. From these results, a thickness of 60 μm of nylon 6 was found to be optimal and usable regardless of the alternative oil used. [Explanation of Symbols]

[0044] 1. Oil-resistant rubber-clad laminate 2 Nylon film 3. Unvulcanized rubber sheet 4. Phenolic resin laminate 5. Polypropylene film (PP film) 10 test pots 11 Rubber carrier 12 Nylon film 13 Test oil 14 Oil container width 15 Sample width

Claims

1. An oil-resistant rubber-clad laminate used as a sealing plate for capacitors, comprising a PP film, a phenolic resin laminate, a rubber sheet, and a nylon film.

2. The rubber sheet is selected from the group consisting of ethylene propylene rubber and butyl rubber, and has a Mooney viscosity (ML) that suppresses flow due to heating and pressurizing even when it is in an unvulcanized state during molding. １＋４ (at 100°C) 85-160, and the curlastometer vulcanization rate index (t Δ８０ The oil-resistant rubber-clad laminate according to claim 1, characterized in that the temperature (130°C) is maintained for 15 to 30 minutes.

3. The oil-resistant rubber-clad laminate according to claim 2, characterized in that the nylon film is unstretched nylon 6.

4. A method for manufacturing an oil-resistant rubber-clad laminate according to claims 1 to 3, comprising: an unvulcanized rubber sheet, a plurality of prepregs, a PP film, and a nylon film A method for manufacturing an oil-resistant rubber-clad laminate obtained by integral molding under heating and pressurizing.

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