Foamed silica gel sealing ring for new energy battery and preparation method of foamed silica gel sealing ring

Abstract

The invention discloses a foamed silica gel sealing ring for a new energy battery and a preparation method of the foamed silica gel sealing ring, and relates to the technical field of foamed silica gel sealing materials. A foaming silica gel sealing ring for a new energy battery comprises 100 parts of gas phase silica gel, 1.8-2 parts of a vulcanizing agent, 4-6 parts of a foaming agent and 0.3-0.5 part of a silica gel defrosting agent, the foaming agent is a mixture of 4, 4 '-oxidized dibenzenesulfonyl hydrazide and triethanolamine, and the vulcanizing agent is a mixture of a bis (2, 2, 4-tetramethyl-2, 5-pentasulfide) agent. By adopting the specific vulcanizing agent and foaming agent, a vulcanizing temperature window and a foaming temperature window in the gas-phase silica gel can be matched with each other, so that the foaming uniformity of the gas-phase silica gel can be effectively improved, the prepared foaming silica gel sealing ring with the comprehensive performance superior to that of an existing foaming silica gel sealing ring is facilitated, and the foaming silica gel sealing ring is more suitable for a new energy battery sealing structure.

Description

Technical Field

[0001] The present invention relates to the technical field of foamed silicone sealing materials, and in particular to a foamed silicone sealing ring for new energy batteries and a preparation method thereof. Background Art

[0002] With the development of new energy vehicles, as the main power source of the vehicle, the performance and safety of the new energy battery pack directly determine the safety of the whole machine. The role of the sealing ring of the battery pack is to prevent external salt spray, water vapor, dust impurities, etc. from entering the interior of the battery pack, so that the new energy battery can work normally in various harsh environments. Due to the excellent elasticity and plasticity of rubber materials themselves, they can effectively adapt to the deformation and vibration of the battery shell and maintain good sealing performance. Therefore, rubber plays a key role in the field of new energy battery sealing.

[0003] In the existing rubber sealing rings, the common production materials are nothing more than ethylene propylene diene monomer rubber (EPDM), silicone rubber or perfluoroether rubber. Although perfluoroether rubber has excellent comprehensive performance, due to its poor processing performance and expensive raw materials, etc., perfluoroether rubber is only used in the sealing of some high-precision and sophisticated equipment at present. Therefore, EPDM and silicone rubber have become the mainstream choices for the sealing of new energy battery packs on the market. Especially the foamed silicone rubber has low water absorption, high rebound rate and low compression set rate, and is more suitable for use as the sealing ring of new energy battery packs compared with EPDM.

[0004] However, due to the relatively complex foaming process, the foaming degree is closely related to various factors such as the selection of raw materials, foaming time, foaming pressure, etc. At present, the foaming uniformity of the foamed silicone rubber sealing rings on the market is not high, not only the compression stress is low, but also there may be some connected pores inside, which greatly affects the waterproofness and service life of the sealing ring. If it is applied to the new energy battery sealing structure for a long time, it is easy to cause the problem of water seepage into the battery pack. Summary of the Invention

[0005] In order to improve the foaming uniformity of foamed silicone rubber, and at the same time improve the mechanical properties and waterproof properties of the sealing ring, so that it can be applied to the sealing structure of new energy battery packs for a long time, the present application provides a foamed silicone sealing ring for new energy batteries and a preparation method thereof.

[0006] In the first aspect, a foamed silicone sealing ring for new energy batteries provided by the present application adopts the following technical solution: A foamed silicone sealing ring for new energy batteries, comprising the following raw materials in parts by weight: Vapor-phase silica gel: 100 parts; Vulcanizing agent: 1.8 - 2 parts; Foaming agent: 4 - 6 parts; Silicone defroster: 0.3 - 0.5 parts; Among them, the blowing agent is a mixture of 4,4'-oxybisbenzenesulfonylhydrazide and triethanolamine, and the vulcanizing agent is a mixture of bis(t-butylperoxyisopropyl)benzene vulcanizing agent and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane vulcanizing agent.

[0007] By adopting the above technical solution, the foaming uniformity of the foamed silicone can be effectively improved, and a foamed silicone sealing ring with comprehensive properties superior to those of existing commercially available products can be prepared. The prepared foamed silicone sealing ring not only has low water absorption, but also has high mechanical properties, and can have lower compression set in both high-temperature and low-temperature environments, which is beneficial to extending the service life of the foamed silicone sealing ring and is more suitable for use in the sealing structure of new energy battery packs.

[0008] Optionally, the 4,4'-oxybisbenzenesulfonylhydrazide and the triethanolamine are in the ratio of (92 - 96):(4 - 8).

[0009] Optionally, the mass ratio of the bis(t-butylperoxyisopropyl)benzene vulcanizing agent and the 2,5-dimethyl-2,5-di(t-butylperoxy)hexane vulcanizing agent is 1:(1.5 - 2).

[0010] By adopting the above technical solution, by using the blowing agent and the vulcanizing agent mixed and compounded in the above ratio, the vulcanization temperature window and the foaming temperature window in the silicone system can be made to match each other. Then, while the blowing agent decomposes and foams, the vulcanizing agent can also promote the vulcanization crosslinking of the silicone accordingly, which not only increases the melt viscosity of the rubber compound during foaming, but also improves the initial cell wall strength, is beneficial to promoting the formation of a uniform closed-cell structure in the silicone, reduces the formation of micropore defects, and thus can effectively improve the foaming uniformity of the foamed silicone sealing ring, and is beneficial to improving the mechanical properties and waterproof properties of the foamed silicone sealing ring.

[0011] Optionally, the fumed silica is self-made fumed silica, and the self-made fumed silica includes the following raw materials in parts by weight: Vinyl raw rubber: 50 - 75 parts; Vinyl methyl phenyl silicone oil: 10 - 18 parts; Hydroxy silicone oil: 16 - 20 parts; Hydrogen-containing silicone oil: 6 - 12 parts; Platinum catalyst: 2 - 2.4 parts; Composite filler: 15 - 30 parts; Inhibitor: 0.12 - 0.15 parts; Among them, the composite filler is a mixture of fumed silica and layered silicate, and the mass ratio of fumed silica to layered silicate is 1:(0.1 - 0.25), and the layered silicate includes at least one of organic montmorillonite, ultrafine mica powder or calcined kaolin.

[0012] By adopting the above technical solution, using the composite filler mixed with fumed silica and layered silicate as the reinforcing filler in the fumed silica gel can not only effectively improve the comprehensive performance of the fumed silica gel, but also the layered silicate cooperates with the fumed silica to form a cavity-interface combination with the silica gel matrix, which can enhance the cell wall strength during subsequent foaming through physical barrier and hydrogen bond action, reduce cell coalescence or collapse, and thus is conducive to improving the foaming uniformity and mechanical properties of the subsequent prepared foamed silica gel sealing ring.

[0013] Optionally, the vinyl raw rubber is mixed by a first raw rubber with a vinyl content of 0.6%-1.4% and a second raw rubber with a vinyl content of 1.5%-2.4%, and the mass ratio of the first raw rubber to the second raw rubber is (6-8):(2-4); The phenyl content of the vinyl methyl phenyl silicone oil is 3.1 mol%-7 mol%; The hydroxyl content of the hydroxyl silicone oil is ≥8.0%; The hydrogen mass fraction of the side hydrogen-containing silicone oil is 0.55%-0.75%.

[0014] By adopting the above technical solution, it is beneficial to improve the crosslinking density and overall strength of the fumed silica gel after sufficient crosslinking, and thus is beneficial to improving the foaming uniformity and mechanical properties of the subsequent prepared foamed silica gel sealing ring.

[0015] Optionally, the composite filler also needs to be subjected to surface modification treatment before addition, and the surface modification treatment of the composite filler includes the following steps: First, stearoyl trimethyl ammonium chloride and N-vinyl pyrrolidone are mixed in proportion and dissolved in an organic solvent to prepare a modification liquid with a concentration of 10%-15%, and then the composite filler is added to the modification liquid at 50 wt%, heated to 65-80 °C, continuously stirred and reacted for 3-4 h, and then subjected to reduced pressure distillation and vacuum drying to obtain the surface-modified composite filler.

[0016] By adopting the above technical solution, it can further expand the interlayer spacing of the layered silicate sheets, improve the microenvironment between layers, be beneficial to converting the hydrophilicity of the inner and outer surfaces of the layered silicate into hydrophobicity, and further enhance the affinity between the composite filler and the silica gel molecular chain. Thus, it is beneficial to improve the modification effect of the composite filler on the foamed silica gel sealing ring through multi-scale interface regulation and functional synergy, and is beneficial to significantly improving the comprehensive performance of the foamed silica gel sealing ring.

[0017] Optionally, the preparation method of the fumed silica gel includes the following steps: A1. By mass, 60% vinyl raw rubber, vinyl methyl phenyl silicone oil, hydroxyl silicone oil, platinum catalyst, and 60% composite filler are fully stirred and kneaded to obtain material A; 40% vinyl raw rubber, hydrogen-containing silicone oil, and inhibitor are fully stirred and kneaded to obtain material B; A2. First, heat material A to 40 - 50 °C and start kneading. After material A is fully softened, add material B and knead fully for 3 - 5 min. Then add 30% composite filler and continue kneading for 30 - 45 min. Then add 10% composite filler and evacuate to -0.08 MPa and continue kneading for 60 - 90 min. After completion, take it out and place it in a mold and cool it to room temperature to obtain gas-phase silica gel.

[0018] By adopting the above technical solution, by kneading material A and material B step by step, the side reaction caused by the premature contact between the platinum catalyst and the hydrogen-containing silicone oil can be effectively avoided. At the same time, by adopting the gradient filler addition strategy, it is beneficial to improve the dispersion of the composite filler in the system, and then can effectively improve the comprehensive performance of the gas-phase silica gel, which is beneficial to improving the foaming uniformity and mechanical properties of the subsequent prepared foamed silicone rubber seal ring.

[0019] In the second aspect, a preparation method of a foamed silicone rubber seal ring for a new energy battery provided by the present application adopts the following technical solution: A preparation method of a foamed silicone rubber seal ring for a new energy battery, comprising the following steps: First, fully knead and extrude each raw material in proportion to obtain a kneaded rubber compound. Then place the kneaded rubber compound at room temperature and let it stand still to obtain a pre-foamed rubber compound. Then put the pre-foamed material into a vulcanizer for mold pressing vulcanization, and quickly open the mold and take it out after the mold pressing vulcanization is completed to obtain a foamed silicone rubber seal ring for a new energy battery.

[0020] By adopting the above technical solution, letting the kneaded rubber compound stand still at room temperature can make the rubber compound recover from fatigue, reduce the collapse or shrinkage of the pores after vulcanization, and is beneficial to improving the foaming uniformity and overall dimensional stability of the seal ring. Moreover, quickly opening the mold after mold pressing vulcanization can make the rubber compound expand instantaneously, preventing it from being unable to expand to the target density after cooling and shaping in the mold. In addition, the preparation method is simple, without the need to prepare too many production equipment, which is beneficial to the subsequent large-scale production and preparation in the factory.

[0021] Optionally, the kneaded rubber compound is placed at room temperature for at least 4 h.

[0022] By adopting the above technical solution, letting the kneaded rubber compound stand still at room temperature for a long time can effectively release the internal stress generated during the kneading process of the kneaded rubber compound, and at the same time eliminate the overall chain segment fatigue, which is beneficial to preventing problems such as pore shrinkage or pore collapse during the subsequent mold pressing vulcanization process, and ensuring the foaming uniformity and mechanical properties of the foamed silicone rubber seal ring.

[0023] Optionally, the mold pressing vulcanization is a two-stage vulcanization process, wherein the first stage of vulcanization needs to be heated to 170 - 180 °C and pre-vulcanized for 15 - 20 min, and the second stage of vulcanization needs to be heated to 200 - 210 °C and vulcanized for 3 - 4 h.

[0024] By adopting the above technical solution, during the first-stage vulcanization process, the decomposition of the blowing agent and the preliminary cross-linking reaction of the vulcanizing agent can be simultaneously initiated, which is beneficial to the formation of a stable cell structure in the initial stage of the foamed silica gel. In the second-stage vulcanization process, the temperature is further increased and the vulcanization time is extended. At this time, the full vulcanization and cross-linking inside the silica gel can be promoted, and at the same time, the low-molecular substances and volatile components in the silica gel can be effectively removed under high-temperature heating, which is beneficial to improving the temperature resistance and dimensional stability of the foamed silica gel sealing ring, making it not easily deformed in high-temperature or low-temperature environments, and being more suitable for the sealing structure of new energy battery packs.

[0025] In summary, the technical solution of this application has at least one of the following beneficial effects: 1. By using a specific vulcanizing agent and blowing agent in a certain proportion, the vulcanization temperature window and the foaming temperature window in the silica gel system can be matched with each other, thereby effectively improving the foaming uniformity of the foamed silica gel, and a foamed silica gel sealing ring with comprehensive performance superior to that of existing commercially available products can be prepared.

[0026] 1. By using a composite filler mixed with fumed silica and layered silicate as the reinforcing filler in the fumed silica gel, not only can the comprehensive performance of the fumed silica gel be effectively improved, but also the layered silicate cooperates with the fumed silica to form a cavity-interface combination with the silica gel matrix, which can enhance the cell wall strength during subsequent foaming through physical barrier and hydrogen bond effects, reduce cell coalescence or collapse, and thus is beneficial to improving the foaming uniformity and mechanical properties of the subsequent prepared foamed silica gel sealing ring.

[0027] 2. By using stearoyl trimethyl ammonium chloride and N-vinyl pyrrolidone to perform surface modification on the composite filler, it is beneficial to convert the hydrophilic inner and outer surfaces of the layered silicate into hydrophobic surfaces, further enhance the affinity between the composite filler and the silica gel molecular chain, and can improve the modification effect of the composite filler on the foamed silica gel sealing ring through multi-scale interface regulation and functional synergy, which is beneficial to significantly improving the comprehensive performance of the foamed silica gel sealing ring. Detailed implementation mode

[0028] The present application will be further described in detail below in combination with preparation examples, examples and comparative examples.

[0029] The vinyl raw rubber was all purchased from Mingyi Silicon Industry. The grade of the first raw rubber was MY110-5, and the vinyl content of this grade was 0.6%-1.4%, specifically controlled within 1%-1.2%; the grade of the second raw rubber was MY110-6, and the vinyl content of this grade was 1.5%-2.4%, specifically controlled within 1.8%-2%.

[0030] The vinyl methyl phenyl silicone oil is selected from the vinyl-terminated polydimethyl diphenyl silicone oil of Ambia Special Silicones. The specific grades are SF 2421 and SF 1721. Among them, the phenyl content of grade SF 2421 is 3.1 mol%, and the viscosity is 1100 cst; the phenyl content of grade SF 1721 is 7 mol%, and the viscosity is 7000 cst.

[0031] The hydroxy silicone oil is selected from Quanli Technology, and the specific grade is QLS-203B. The hydroxy content of this grade is ≥8.0%.

[0032] The hydrogen-containing silicone oil is selected from the side hydrogen-containing silicone oil of Runhe Materials. The specific grades are RH-H502 and RH-H503. Among them, the hydrogen content of grade RH-H502 is 0.75%-0.77%, and the hydrogen content of grade RH-H503 is 0.55%-0.57%.

[0033] The fumed silica is selected from the R974 hydrophobic fumed silica of Evonik. The organic montmorillonite is selected from I.44P of Nanocor. The ultrafine mica powder is selected from GB-2 of Greentec New Materials. The calcined kaolin is selected from the calcined kaolin of Dilane Chemical Industry, and the mesh number is 2000.

[0034] The silica gel defroster is selected from Qianhai Jishengya Technology, and the grade is CS-3050.

[0035] Preparation Example

Preparation Example 1

[0036] Among them, the vinyl raw rubber is composed of the first raw rubber and the second raw rubber mixed in a mass ratio of 6:4, that is, the vinyl raw rubber includes 48 kg of the first raw rubber and 32 kg of the second raw rubber; the vinyl methyl phenyl silicone oil is selected with the grade of SF 1721; the hydrogen-containing silicone oil is selected with the grade of RH-H502; the composite filler is composed of fumed silica and organic montmorillonite mixed in a mass ratio of 1:0.25, that is, the composite filler includes 12 kg of fumed silica and 3 kg of organic montmorillonite, and the inhibitor is selected as 1-ethynylcyclohexanol.

[0037] A preparation method of a self-made fumed silica gel, comprising the following steps: A1. By mass, 60% of the vinyl raw rubber, vinyl methyl phenyl silicone oil, hydroxy silicone oil, chloroplatinic acid, and 60% of the composite filler are fully stirred and kneaded to obtain material A; 40% of the vinyl raw rubber, hydrogen-containing silicone oil, and inhibitor are fully stirred and kneaded to obtain material B; A2. First, heat Material A to 50°C and start kneading. After Material A becomes fully soft, add Material B and knead thoroughly for 3 min. Then add 30% of the composite filler and continue kneading for 30 min. Next, add 10% of the composite filler, apply a vacuum of -0.08 MPa, and continue kneading for 90 min. After completion, take it out, place it in a mold, and cool and shape it to room temperature to obtain the fumed silica gel.

[0038]

Preparation Example 2

[0039] Among them, the vinyl raw rubber is composed of the first raw rubber and the second raw rubber mixed in a mass ratio of 8:2, that is, the vinyl raw rubber includes 40 kg of the first raw rubber and 10 kg of the second raw rubber; the vinyl methyl phenyl silicone oil is selected with the brand number SF 2421; the hydrogen-containing silicone oil is selected with the brand number RH-H503; the composite filler is composed of fumed silica and ultrafine mica powder mixed in a mass ratio of 1:0.12, that is, the composite filler includes 25 kg of fumed silica and 3 kg of ultrafine mica powder, and the inhibitor is selected as 1-ethynylcyclohexanol.

[0040] A preparation method of a self-made fumed silica gel, comprising the following steps: A1. By mass, fully stir and knead 60% of the vinyl raw rubber, vinyl methyl phenyl silicone oil, hydroxy silicone oil, chloroplatinic acid, and 60% of the composite filler to obtain Material A; fully stir and knead 40% of the vinyl raw rubber, hydrogen-containing silicone oil, and inhibitor to obtain Material B; A2. First, heat Material A to 45°C and start kneading. After Material A becomes fully soft, add Material B and knead thoroughly for 5 min. Then add 30% of the composite filler and continue kneading for 45 min. Next, add 10% of the composite filler, apply a vacuum of -0.08 MPa, and continue kneading for 60 min. After completion, take it out, place it in a mold, and cool and shape it to room temperature to obtain the fumed silica gel.

[0041]

Preparation Example 3

Preparation Example 1

[0042] In this preparation example, the vinyl methyl phenyl silicone oil is selected with the brand number SF 2421.

[0043]

Preparation Example 4

Preparation Example 1

[0044] In this preparation example, the composite filler is prepared by mixing fumed silica and ultrafine mica powder in a mass ratio of 1:0.25, that is, the composite filler includes 12 kg of fumed silica and 3 kg of ultrafine mica powder.

[0045] [Preparation Example 5] A self-made gas phase silica gel, which differs from [Preparation Example 1] in that the composite filler is different.

[0046] In this preparation example, the composite filler is prepared by mixing fumed silica and calcined kaolin in a mass ratio of 1:0.25, that is, the composite filler includes 12 kg of fumed silica and 3 kg of calcined kaolin.

[0047] [Preparation Example 6] A self-made gas phase silica gel, which differs from [Preparation Example 1] in that the composite filler is different.

[0048] In this preparation example, the composite filler needs to undergo surface modification before mixing. Specifically, the following steps are included: first, stearyl trimethyl ammonium chloride and N-vinyl pyrrolidone are mixed in a mass ratio of 4:1 and dissolved in N, N-dimethylformamide to prepare a modified liquid with a concentration of 10%, and then the composite filler is added to the modified liquid at 50wt%, heated to 80°C, stirred and reacted for 3h, distilled under reduced pressure and dried in vacuum to obtain a surface-modified composite filler.

[0049] [Preparation Example 7] A self-made gas phase silica gel, which differs from [Preparation Example 1] in that no composite filler is added.

[0050] In this preparation example, an equal amount of fumed silica is used to replace the composite filler. Example

[0051] [Example 1] A foamed silicone seal ring for a new energy battery comprises the following raw materials in parts by weight: 100 kg of fumed silicone, 1.8 kg of a vulcanizing agent, 4 kg of a foaming agent and 0.3 kg of a silicone defrosting agent.

[0052] Among them, the gas-phase silica gel is made of homemade gas-phase silica gel, specifically a homemade gas-phase silica gel prepared in [Preparation Example 1]; the vulcanizing agent is a mixture of bis(di-tetra-)sulfurizing agent and bis(di-penta-)sulfurizing agent in a mass ratio of 1:2, that is, it includes 0.6kg of bis(di-tetra-)sulfurizing agent and 1.2kg of bis(di-penta-)sulfurizing agent; the foaming agent is a mixture of 4,4'-oxidized bisbenzenesulfonyl hydrazide and triethanolamine in a mass ratio of 92:8, that is, it includes 3.68kg of 4,4'-oxidized bisbenzenesulfonyl hydrazide and 0.32kg of triethanolamine.

[0053] A method for preparing a foamed silicone sealing ring for a new energy battery comprises the following steps: First, mix all raw materials in proportion and extrude them fully to obtain a kneaded rubber compound. Then, let the kneaded rubber compound stand at room temperature for 4 hours to obtain a pre-foamed rubber compound. Next, put the pre-foamed material into a vulcanizer for two-stage compression molding vulcanization. Among them, for the first-stage vulcanization, it needs to be heated to 180 °C and pre-vulcanized for 15 minutes. For the second-stage vulcanization, it needs to be heated to 200 °C and vulcanized for 4 hours. After the compression molding vulcanization is completed, quickly open the mold, and after cooling, a foamed silica gel sealing ring for a new energy battery is obtained.

[0054]

Example 2

[0055] Among them, the fumed silica gel is a self-made fumed silica gel, specifically a self-made fumed silica gel prepared in

Preparation Example 2

[0056] A preparation method of a foamed silica gel sealing ring for a new energy battery, comprising the following steps: First, mix all raw materials in proportion and extrude them fully to obtain a kneaded rubber compound. Then, let the kneaded rubber compound stand at room temperature for 5 hours to obtain a pre-foamed rubber compound. Next, put the pre-foamed material into a vulcanizer for two-stage compression molding vulcanization. Among them, for the first-stage vulcanization, it needs to be heated to 170 °C and pre-vulcanized for 20 minutes. For the second-stage vulcanization, it needs to be heated to 210 °C and vulcanized for 3 hours. After the compression molding vulcanization is completed, quickly open the mold, and after cooling, a foamed silica gel sealing ring for a new energy battery is obtained.

[0057]

Example 3

Example 1

[0058] In this example, the fumed silica gel is a commercially available fumed silica gel, specifically selected from Tian'an Silica Gel Technology, with the brand number TN-940. The marked hardness value of this commercially available fumed silica gel is 40 degrees.

[0059]

Example 4

Example 1

[0060] In this example, the fumed silica gel is specifically a self-made fumed silica gel prepared in

Preparation Example 3

[0061]

Example 5

Example 1

[0062] In this example, the fumed silica gel is specifically selected as a self-made fumed silica gel prepared in

Preparation Example 4

[0063]

Example 6

Example 1

[0064] In this example, the fumed silica gel is specifically selected as a self-made fumed silica gel prepared in

Preparation Example 5

[0065]

Example 7

Example 1

[0066] In this example, the fumed silica gel is specifically selected as a self-made fumed silica gel prepared in

Preparation Example 6

[0067]

Example 8

Example 1

[0068] In this example, the mixed rubber compound is allowed to stand at room temperature for 2 h.

[0069] Comparative Example

Comparative Example 1

[0070]

Comparative Example 2

Example 1

[0071] In this comparative example, bis(2,4-dichlorobenzoyl) peroxide is used alone as the vulcanizing agent.

[0072]

Comparative Example 3

Example 1

[0073] In this comparative example, bis(2,5-dichlorobenzoyl) peroxide is used alone as the vulcanizing agent.

[0074]

Comparative Example 4

Preparation Example 1

[0075] In this comparative example, the fumed silica gel is a self-made fumed silica gel prepared in

Preparation Example 7

[0076]

Comparative Example 5

Preparation Example 1

[0077] In this comparative example, the mixed rubber compound is not left standing at room temperature after extrusion, and is directly sent into the vulcanizing agent for compression molding and vulcanization.

[0078] Performance test data 1. Water absorption rate: Refer to the water absorption test in 《ASTM D1056 Standard Specification for Flexible Cellular Materials - Sponge Rubber and Foamed Rubber》 for detection, and calculate and record the water absorption rate (%) of each example and comparative example.

[0079] 2. Waterproof and dustproof performance: Use the foamed silicone rubber sealing rings prepared in each example and comparative example to seal the battery cases of the same specifications, and conduct IP68 waterproof and dustproof tests. The test time for the waterproof test is 120h. If there is no water or dust entering the inside of the battery case, it is recorded as passed; if not, record the situation of water and dust entering the inside of the battery case.

[0080] 3. Compression stress: Refer to the compression deformation test in 《ASTM D1056 Standard Specification for Flexible Cellular Materials - Sponge Rubber and Foamed Rubber》 for detection, and record the compression stress (MPa) when the foamed silicone rubber sealing rings of each example and comparative example are compressed to 50%.

[0081] 4. High and low temperature compression set performance: Refer to 《GB / T 7759.1-2015 Rubber, vulcanized or thermoplastic - Determination of compression set - Part 1: At ambient and elevated temperatures》 and 《GB / T 7759.1-2014 Rubber, vulcanized or thermoplastic - Determination of compression set - Part 2: At low temperatures》 to conduct high and low temperature compression set performance tests. Each example and comparative example are tested in 5 groups, and record the average compression set (%) of the 5 groups of tests at high and low temperatures. Among them, the high temperature test conditions are 50% compression rate, temperature set at 85°C, humidity set at 85%, and test time is 1000h; the low temperature test conditions are 50% compression rate, temperature set at -40°C, and test time is 240h.

[0082] Table 1 Partial performance test data of foamed silicone rubber sealing rings Combined with Examples 1-3 and Comparative Example 1 and the data in Table 1, it can be seen that by using self-made gas-phase silica gel and combining it with a specific proportion of foaming agent, vulcanizing agent and silica gel defroster, a foamed silica gel sealing ring with better comprehensive performance than the existing commercially available ones can be obtained. It not only has low water absorption and high strength, but also has a lower compression set rate at high and low temperature environments, which further reflects that the sealing ring can have excellent elastic retention ability, cross-linking network stability and microstructural integrity in extreme environments. In addition, by using commercially available gas-phase silica gel with a marked hardness of 40 and combining it with other additives in Example 1, a foamed silica gel sealing ring with a much lower compression set rate at high and low temperatures than the commercially available sealing ring can also be obtained, but its comprehensive performance is still lower than that of the foamed silica gel sealing ring made of self-made gas-phase silica gel. Further combining Examples 1 and Comparative Examples 2-3 and the data in Table 1, it can be seen that when the foaming agent is 4,4'-oxybis(benzenesulfonylhydrazide) and triethanolamine, and the vulcanizing agent is a compound of bis(2,4-dichlorobenzoyl) peroxide and bis(2,5-dichlorobenzoyl) peroxide in a certain proportion, the performance of the foamed silica gel sealing ring obtained is better than when using a single vulcanizing agent. This is because when using a single vulcanizing agent, the vulcanization temperature window of silica gel does not match the foaming temperature window. Among them, 4,4'-oxybis(benzenesulfonylhydrazide) is a medium-high temperature foaming agent, and its decomposition temperature is approximately in the range of 150-170°C. However, bis(2,4-dichlorobenzoyl) peroxide is a low-temperature vulcanizing agent. If bis(2,4-dichlorobenzoyl) peroxide is used alone, it will cause premature cross-linking and vulcanization of silica gel, resulting in too high cross-linking density. When the temperature rises, the gas generated by the decomposition of the foaming agent cannot break through the cross-linking network, thus causing uneven foaming and affecting the rebound performance of the sealing ring. Similarly, bis(2,5-dichlorobenzoyl) peroxide is a high-temperature vulcanizing agent. When used alone, it may cause premature foaming. However, at this time, the melt strength of the colloid and the strength of the cell wall are insufficient, making it difficult to effectively encapsulate the gas, forming large and uneven open-cell structures, which is not conducive to application in sealing structures.

[0083] Combined with Example 1 and Example 4 and the data in Table 1, it can be seen that when the phenyl content of vinyl methyl phenyl silicone oil is 3.1 mol%-7 mol%, with the increase of the benzene content and viscosity in the gas-phase silica gel, the low-temperature compression set of the foamed silica gel sealing ring can be further reduced, and at the same time, the changes in other properties are not significant, which is conducive to obtaining a foamed silica gel sealing ring with better comprehensive performance. This may be because the introduction of a small amount of phenyl not only inhibits the crystallization behavior of some silane segments at low temperatures and reduces the brittle temperature of the foamed silica gel, but also the volume of phenyl is relatively large. The introduction of a small amount can moderately increase the chain spacing, enabling the foamed silica gel to still maintain the chain segment movement ability at low temperatures. However, as is well known, excessive phenyl will increase the overall rigidity of the chain segments due to steric hindrance effects. Therefore, when controlling the phenyl content of vinyl methyl phenyl silicone oil ≤ 7 mol%, the low-temperature performance of the foamed silica gel sealing ring can be optimized to a certain extent.

[0084] Combined with Example 1, Examples 5-7 and Comparative Example 4 and the data in Table 1, it can be seen that when a composite filler mixed with fumed silica and layered silicate is used as a reinforcing filler in the fumed silica gel, compared with the fumed silica gel prepared by using fumed silica alone, the subsequent prepared foamed silica gel seals all have relatively good performance. Moreover, when different layered silicates are compounded with fumed silica, the influence of the composite filler on the performance of the foamed silica gel seal is different. Among them, the comprehensive performance of the organic montmorillonite is the best, not only with low water absorption, but also with a relatively high overall compression stress and low compression set. This may be because the surface of the layered silicate has more active sites and can act as an efficient heterogeneous nucleation site during the vulcanization and foaming of the silica gel, not only reducing the energy barrier during the foaming process and promoting uniform bubble nucleation, but also the layered silicate cooperating with fumed silica to form a cavity-interface bond with the silica gel matrix, enhancing the bubble wall strength through physical barrier and hydrogen bond action and reducing cell coalescence or collapse.

[0085] In addition, by using stearyl trimethyl ammonium chloride and N-vinyl pyrrolidone to conduct surface modification treatment on the organic montmorillonite, the modification effect of the composite filler on the foamed silica gel seal can be further improved, and the comprehensive performance is better. This may be because after treatment with stearyl trimethyl ammonium chloride and N-vinyl pyrrolidone, the interlayer spacing of the layered silicate can be further expanded and the microenvironment between layers can be improved, converting the hydrophilicity of the inner and outer surfaces of the layered silicate into hydrophobicity, further enhancing the affinity between the composite filler and the silica gel molecular chain, and thus being conducive to significantly improving the comprehensive performance of the material through multi-scale interface regulation and functional synergy.

[0086] Combined with Example 1, Example 8 and Comparative Example 5 and the data in Table 1, it can be seen that during the preparation process of the foamed silica gel seal, standing the mixed rubber compound at room temperature for a period of time can significantly improve the sealing performance of the subsequently prepared seal, and at the same time can also reduce the compression set of the seal at high and low temperatures. This may be because the raw materials are subjected to a large shear stress during the mixing process and fatigue is generated during continuous shear and stretching, and thus bubble shrinkage or bubble collapse is likely to occur after the rubber compound is molded and vulcanized, directly affecting the foaming uniformity and mechanical properties of the seal. However, during the standing process at room temperature, the mixed rubber compound can gradually release internal stress and recover from fatigue, which is beneficial to preventing subsequent bubble shrinkage or bubble collapse and ensuring the foaming uniformity and mechanical properties of the seal.

[0087] This specific implementation manner is only an interpretation of the present application and does not limit the present application. Those skilled in the art can make modifications to this specific implementation manner without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A foamed silicone rubber sealing ring for a new energy battery, characterized in that, It comprises the following raw materials in parts by weight: Fumed silica: 100 parts; Vulcanizing agent: 1.8 - 2 parts; Blowing agent: 4 - 6 parts; Silicone defroster: 0.3 - 0.5 part; Among them, the blowing agent is a mixture of 4,4'-oxybis(benzenesulfonyl hydrazide) and triethanolamine, and the vulcanizing agent is a mixture of bis(tetrabutylammonium) disulfide and bis(pentamethylcyclopentadienyl) iron(II) disulfide.

2. A foamed silicone rubber sealing ring for a new energy battery according to claim 1, characterized in that: The ratio of 4,4'-oxybis(benzenesulfonyl hydrazide) to triethanolamine is (92 - 96):(4 - 8).

3. The foamed silicone rubber sealing ring for a new energy battery according to claim 1, characterized in that: The mass ratio of bis(tetrabutylammonium) disulfide to bis(pentamethylcyclopentadienyl) iron(II) disulfide is 1:(1.5 - 2).

4. The foamed silicone rubber sealing ring for a new energy battery according to claim 1, wherein: The fumed silica is self-made fumed silica, and the self-made fumed silica comprises the following raw materials in parts by weight: Vinyl raw rubber: 50 - 75 parts; Vinyl methyl phenyl silicone oil: 10 - 18 parts; Hydroxy silicone oil: 16 - 20 parts; Hydrogen-containing silicone oil: 6 - 12 parts; Platinum catalyst: 2 - 2.4 parts; Composite filler: 15 - 30 parts; Inhibitor: 0.12 - 0.15 part; Among them, the composite filler is a mixture of fumed silica and layered silicate, and the mass ratio of fumed silica to layered silicate is 1:(0.1 - 0.25). The layered silicate includes at least one of organic montmorillonite, ultrafine mica powder or calcined kaolin.

5. A foamed silicone rubber sealing ring for a new energy battery according to claim 4, characterized in that: The vinyl raw rubber is a mixture of a first raw rubber with a vinyl content of 0.6% - 1.4% and a second raw rubber with a vinyl content of 1.5% - 2.4%, and the mass ratio of the first raw rubber to the second raw rubber is (6 - 8):(2 - 4); The phenyl content of the vinyl methyl phenyl silicone oil is 3.1 mol% - 7 mol%; The hydroxyl content of the hydroxy silicone oil is ≥8.0%; The hydrogen mass fraction of the side hydrogen-containing silicone oil is 0.55% - 0.75%.

6. The foamed silicone rubber sealing ring for a new energy battery according to claim 4, characterized in that: Before adding, the composite filler also needs to be subjected to surface modification treatment. The surface modification treatment of the composite filler includes the following steps: First, stearyl trimethyl ammonium chloride and N-vinyl pyrrolidone are mixed in proportion and dissolved in an organic solvent to prepare a modification liquid with a concentration of 10% - 15%. Then, the composite filler is added to the modification liquid at 50 wt%, heated to 65 - 80 °C, continuously stirred and reacted for 3 - 4 h, distilled under reduced pressure and vacuum dried to obtain the surface-modified composite filler.

7. The foamed silica gel sealing ring for a new energy battery according to claim 4, wherein: The preparation method of the fumed silica includes the following steps: A1. By mass, 60% vinyl raw rubber, vinyl methyl phenyl silicone oil, hydroxy silicone oil, platinum catalyst and 60% composite filler are fully stirred and kneaded to obtain material A; 40% vinyl raw rubber, hydrogen-containing silicone oil and inhibitor are fully stirred and kneaded to obtain material B; A2. First, heat material A to 40 - 50 °C and start kneading. After material A is fully softened, add material B and fully knead for 3 - 5 min. Then add 30% composite filler and continue kneading for 30 - 45 min. Then add 10% composite filler and evacuate to -0.08 MPa and continue kneading for 60 - 90 min. After completion, take out and place in a mold and cool to room temperature to obtain fumed silica.

8. A preparation method of a foamed silica gel sealing ring for a new energy battery, which is applicable to the foamed silica gel sealing ring for a new energy battery according to any one of claims 1-7, and is characterized in that, It includes the following steps: First, the raw materials are fully mixed and extruded in proportion to obtain a mixed rubber material, and then the mixed rubber material is placed at room temperature to stand to obtain a pre-foamed rubber material, and then the pre-foamed material is put into a vulcanizer for compression vulcanization, and after the compression vulcanization is completed, the mold is quickly opened and taken out to obtain a foamed silicone sealing ring for new energy batteries.

9. The preparation method of a foamed silica gel sealing ring for a new energy battery according to claim 8, characterized in that: The mixed rubber material is left to stand at room temperature for not less than 4 hours.

10. The preparation method of a foamed silica gel sealing ring for a new energy battery according to claim 8, wherein: The compression vulcanization is a two-stage vulcanization process, wherein the first stage vulcanization needs to be heated to 170-180° C. and continue pre-vulcanization for 15-20 minutes, and the second stage vulcanization needs to be heated to 200-210° C. and continue vulcanization for 3-4 hours.

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