Full-temperature-range silica gel heat-conducting structural adhesive for power battery and preparation method thereof

Abstract

The invention relates to the technical field of heat-conducting structural adhesives, in particular to a full-temperature-range silica gel heat-conducting structural adhesive for a power battery and a preparation method of the full-temperature-range silica gel heat-conducting structural adhesive. The adhesive is prepared from raw materials in percentage by weight as follows: 40%-45% of polydimethylsiloxane, 5%-10% of organosilicon modified epoxy resin, 3%-6% of methacrylate, 5%-10% of modified starch paste, 1%-2% of a cross-linking agent, 15%-20% of filler, 0.5%-1% of a catalyst and the balance of a diluent, and modified starch and water are mixed and gelatinized to obtain the modified starch paste. According to the formula, the silica gel structural adhesive can keep stable performance within the temperature range of-40 DEG C to 350 DEG C, meanwhile, the silica gel structural adhesive has good adhesive performance, and the adhesive performance of polyurethane and epoxy resin structural adhesives can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of thermally conductive structural adhesives, and more specifically, to a silicone thermally conductive structural adhesive for power batteries across the entire temperature range and a preparation method thereof. Background Art

[0002] Structural adhesives are mainly used for the bonding of power batteries, and at the same time, structural adhesives also have the function of a heat conduction medium. It can efficiently conduct the heat generated inside the battery pack to the cooling system or the external environment, thereby reducing the temperature of the battery pack and avoiding performance degradation or safety accidents caused by high temperature. The efficient heat conduction performance helps to extend the service life of the battery and improve the overall performance of the battery pack.

[0003] Currently, the structural adhesives used for power batteries mainly include polyurethane structural adhesives, epoxy resin structural adhesives, and silicone structural adhesives. Among them, polyurethane structural adhesives have strong tensile strength and stability, and can maintain a firm bond to power battery components for a long time. However, the heat resistance of polyurethane structural adhesives is relatively poor, and their performance will decline or fail after long-term use in a high-temperature environment. Epoxy resin structural adhesives have good adhesion to materials and can ensure the tight connection between power battery components. However, the epoxy resin structural adhesives have weak resistance to thermal and cold changes, and cracks and water seepage are likely to occur after long-term use in a thermally and cold-alternating environment. Moreover, the cured epoxy resin structural adhesives are relatively hard and brittle, and are prone to pulling damage to power battery components when subjected to high mechanical stress. Silicone structural adhesives can maintain stable performance within a very wide temperature range, can be used at high temperatures of 200 - 350 °C, and can also be used at low temperatures of -40 °C, meeting the use requirements of power batteries under different working conditions. However, in actual use, it is found that the adhesiveness of the silicone structure is lower than that of polyurethane structural adhesives and epoxy resin structural adhesives. In order to ensure its bonding performance, the bonded surface usually needs to be specially treated. For example, applying a primer or performing other surface modification treatments to further improve the bonding effect of the silicone structural adhesive, and the operation process is relatively troublesome. Summary of the Invention

[0004] In order to improve the bonding performance of the silicone structure, the present application provides a silicone thermally conductive structural adhesive for power batteries across the entire temperature range and a preparation method thereof.

[0005] In a first aspect, the present application provides a silicone thermally conductive structural adhesive for power batteries across the entire temperature range, adopting the following technical solution: A silicone thermally conductive structural adhesive for power batteries across the entire temperature range is prepared from the following raw materials in weight percentages: Polydimethylsiloxane 40 - 45% Organosilicon-modified epoxy resin 5 - 10% Methacrylate 3 - 6% Modified starch paste: 5 - 10% Crosslinking agent: 1 - 2% Filler: 15 - 20% Catalyst: 0.5 - 1% The balance is diluent The modified starch paste is obtained by mixing and gelatinizing modified starch and water.

[0006] Preferably, the weight ratio of modified starch to water is (5 - 10):(10 - 15).

[0007] By adopting the above technical solution, not only can the silicone structural adhesive maintain stable performance within the temperature range of -40 - 350°C, but also it has good adhesion performance and can achieve the adhesion performance of polyurethane and epoxy resin structural adhesives.

[0008] In this application, polydimethylsiloxane is used as the main raw material to maintain the high-temperature and low-temperature resistance characteristics of the silicone structural adhesive, which helps to maintain the stability of the structural adhesive in a wide temperature range. The organosilicon-modified epoxy resin contains the functional groups of epoxy resin, which enhances the adhesion between the silicone structural adhesive and different materials. At the same time, the rigid structure of epoxy resin is combined with the flexible structure of polydimethylsiloxane to form an adhesion that has both certain strength and good toughness, thereby improving the ability of the structural adhesive to resist thermal and cold changes and reducing the risk of cracks and water seepage. Methacrylate participates in the crosslinking reaction as an active monomer, which increases the crosslinking density and weather resistance of the structural adhesive and helps to form a denser and more stable network structure, thus further enhancing the adhesion strength and durability. The hydroxyl functional groups in the modified starch paste can form hydrogen bonds or chemical bonds with the surface of the substrate, thereby enhancing the adhesion strength between the structural adhesive and the power battery components. At the same time, the modification treatment improves the compatibility between the starch molecules and the silicone matrix, reduces the interfacial defects, and further improves the adhesion effect. And an appropriate amount of modified starch paste can adjust the viscosity and fluidity of the structural adhesive, making it easier to construct and coat. The modified starch paste can increase the volume of the structural adhesive and reduce the usage amount of other high-cost raw materials, thereby reducing the production cost to a certain extent.

[0009] Preferably, the modified starch paste is prepared by the following method: 1) Mix starch and water, heat up to 60 - 70°C and stir to obtain a semi-gelatinized product; 2) Heat the semi-gelatinized product, sodium alginate, emulsifier, and polyvinyl alcohol to 90 - 95°C and stir evenly to obtain mixture A; 3) Mix mixture A and boric acid solution evenly to obtain the modified starch paste.

[0010] By adopting the above technical solution, the adhesion of the modified starch paste is further improved, which is beneficial to improving the adhesion performance of the full-temperature-range silicone thermal conductive structural adhesive for power batteries.

[0011] In step 1), the starch granules are made to absorb water and swell, and part of the starch molecules dissolve in water to form a semi-paste. The starch in the semi-pasted state retains the granular structure and has a certain fluidity, facilitating subsequent modification. In step S2, sodium alginate and polyvinyl alcohol are used as additives, which can further improve the adhesion performance of starch. Among them, sodium alginate has good thickening and stability, which can enhance the viscosity and stability of starch; the emulsifier helps the uniform dispersion and mixing among the components; polyvinyl alcohol can form hydrogen bonds with starch molecules through its hydroxyl groups, further improving the adhesion and stability of starch. In step 3), boric acid can react with the hydroxyl groups in starch molecules and the hydroxyl groups in additives such as sodium alginate and polyvinyl alcohol to form a cross-linked structure, enhancing the stability of the modified starch and enabling it to maintain good bonding performance under different environmental conditions.

[0012] Preferably, the parts by weight for preparing the modified starch are as follows: Starch: 5 - 10 parts Water: 12 - 15 parts Sodium alginate: 2 - 4 parts Emulsifier: 1 - 2 parts Polyvinyl alcohol: 3 - 5 parts Boric acid solution: 0.5 - 1 part.

[0013] By adopting the above technical solution, the dosage ratio of preparing the modified starch is optimized, further improving the adhesion performance of starch, ensuring the uniform dispersion of the modified starch in the silica gel matrix, which helps to form a denser structure, and further enhancing the adhesion performance, stability, thermal conductivity and durability of the silica gel thermal conductive structural adhesive for high-power batteries at all temperatures, providing strong support for the safe operation and performance improvement of the battery pack.

[0014] Preferably, the boric acid solution is obtained by mixing boric acid and water in a weight ratio of (2 - 3):8.

[0015] By adopting the above technical solution, the concentration of the boric acid solution is appropriate, which is beneficial to regulating and controlling the cross-linking process and ensuring the bonding performance of the modified starch.

[0016] Preferably, the filler is pretreated through the following steps: By weight, 15 - 20 parts of filler, 4 - 8 parts of carboxymethyl cellulose and 20 - 25 parts of water are stirred until the carboxymethyl cellulose is dissolved, then 3 - 5 parts of 3 - acryloxypropyltrimethoxysilane are added, stirred, filtered, and the filter residue is taken to obtain the pretreated filler.

[0017] By adopting the above technical solution, carboxymethyl cellulose can effectively reduce the agglomeration between filler particles, make the filler disperse more uniformly in the structural adhesive, and make the filler disperse and stabilize more uniformly in the structural adhesive, reducing the phenomenon of performance degradation or failure of the filler caused by physical or chemical factors during use. At the same time, the pretreated filler can also improve the adhesion performance of the filler. 3-Propoxypropyltrimethoxysilane can react chemically with the filler surface to form a chemically bonded interfacial layer, enhancing the adhesion performance between the filler and the structural adhesive matrix and improving the overall strength of the structural adhesive.

[0018] Preferably, the average particle size of the filler includes 50-100 nm and 100-300 nm.

[0019] By adopting the above technical solution, the average particle size of 50-100 nm has a large specific surface area, which can form more contact points with the matrix material, thereby enhancing the interaction force between the filler and the matrix, improving the adhesion strength of the structural adhesive, and at the same time forming more heat conduction channels to enhance the heat conduction performance; the average particle size of 100-300 nm can fill the voids between nano-scale fillers, form a more compact packing structure, and improve the overall performance. The combination of the two can improve the heat conduction performance and bonding performance of the all-temperature silicone thermal conductive structural adhesive for power batteries.

[0020] Preferably, the polydimethylsiloxane is vinyl-terminated polydimethylsiloxane. The molecular weight of the vinyl-terminated polydimethylsiloxane rubber is 500000-1000000 g / mol, and the vinyl content in the vinyl-terminated polydimethylsiloxane is 0.1-0.3 mmol / g.

[0021] By adopting the above technical solution, optimizing the type and parameters of polydimethylsiloxane is easy to control the cross-linking reaction, thereby improving the processing stability and efficiency. At the same time, the all-temperature silicone thermal conductive structural adhesive for power batteries can maintain stable physical and chemical properties within a very wide temperature range and is suitable for applications in various extreme situations.

[0022] Preferably, the organosilicon-modified epoxy resin is prepared by the following method: By weight, 50-200 parts of 3-hydroxypropyltrimethoxysilane, 100-120 parts of epoxy resin, and 3-5 parts of dibutyl nitrosamine are mixed, heated to 125-130 °C for reaction, and the vacuum degree of the reaction is 0.06-0.1 MPa to obtain the organosilicon-modified epoxy resin.

[0023] By adopting the above technical solution, the silicon-oxygen bond in 3-hydroxypropyltrimethoxysilane reacts with the epoxy group of the epoxy resin to form a copolymer, which not only retains the original excellent properties of the epoxy resin, but also introduces the characteristics of the silicon-oxygen bond. The silicon-oxygen bond has a strong bond energy and can form a stronger intermolecular interaction with the surface of the adhered material. When used in the full-temperature-range silica gel thermal conductive structural adhesive for power batteries, it can improve its bonding strength.

[0024] Preferably, the crosslinking agent is at least one of methyltrimethoxysilane, methyltriacetoxime silane, vinyltriacetoxime silane, methyltriethoxysilane or vinyltrimethoxysilane.

[0025] Preferably, the crosslinking agent is obtained by mixing methyltriethoxysilane and vinyltriacetoxime silane in a weight ratio of (1-3):0.8.

[0026] By adopting the above technical solution, the crosslinking efficiency of the full-temperature-range silica gel thermal conductive structural adhesive for power batteries is further improved, and the bonding performance stability, thermal conductivity, high and low temperature resistance and durability of the full-temperature-range silica gel thermal conductive structural adhesive for power batteries are improved.

[0027] In a second aspect, the present application provides a preparation method of a full-temperature-range silica gel thermal conductive structural adhesive for power batteries, adopting the following technical solution: A preparation method of a full-temperature-range silica gel thermal conductive structural adhesive for power batteries includes the following preparation steps: S1. Mix and stir the diluent, methacrylate and organosilicon-modified epoxy resin, and then add the modified starch paste and stir to obtain mixture A; S2. Stir the polydimethylsiloxane and the filler evenly, then add mixture A and stir, and then add the crosslinking agent and the catalyst and stir to obtain the full-temperature-range silica gel thermal conductive structural adhesive for power batteries.

[0028] By adopting the above technical solution, each component can be fully mixed evenly, the synergistic effect of each component is realized, the bonding performance stability, thermal conductivity and durability of the full-temperature-range silica gel thermal conductive structural adhesive for power batteries are further improved, the phenomenon of filler agglomeration is avoided, and the uniformity and consistency of the structural adhesive are improved.

[0029] In summary, the present application has the following beneficial effects: 1. Full-temperature-range stability: The structural adhesive can maintain stable performance at -40°C to 350°C, meeting the usage requirements of power batteries under different working conditions, especially the stability at high and low temperatures is significantly improved.

[0030] 2. Excellent adhesion: By adding components such as silicone-modified epoxy resin, methacrylate, modified starch, and cross-linking agent, the adhesion performance of the silicone structural adhesive is enhanced, enabling it to approach or even exceed the adhesion strength of polyurethane and epoxy resin structural adhesives, and reducing the dependence on special treatment of the bonded surface.

[0031] 3. Good thermal conductivity: The common use of silicone-modified epoxy resin, methacrylate, and fillers helps the effective conduction and dissipation of heat during the operation of power batteries, improving the safety and service life of the batteries.

[0032] 4. Strong resistance to thermal and cold changes: Compared with pure silicone or epoxy resin, this structural adhesive has stronger resistance to thermal and cold changes, reducing the risk of problems such as cracks and water seepage in a thermal and cold alternating environment.

[0033] 5. Excellent mechanical properties: While ensuring the adhesion strength, this structural adhesive also has a certain degree of flexibility and tensile resistance, enabling it to better adapt to the mechanical stress changes that may occur during the use of power batteries. Detailed implementation methods

[0034] Preparation examples Preparation example 1 A silicone-modified epoxy resin is prepared by the following method: Mix 50 g of 3-hydroxypropyltrimethoxysilane, 100 g of epoxy resin (bisphenol A epoxy resin E-20), and 3 g of dibutyl nitrosamine, heat up to 125 °C for reaction, the vacuum degree of the reaction is 0.06 MPa, and react for 5 h to obtain the silicone-modified epoxy resin.

[0035] Preparation example 2 A silicone-modified epoxy resin is prepared by the following method: Mix 80 g of 3-hydroxypropyltrimethoxysilane, 150 g of epoxy resin (bisphenol A epoxy resin E-24), and 4 g of dibutyl nitrosamine, heat up to 128 °C for reaction, the vacuum degree of the reaction is 0.08 MPa, and react for 5.5 h to obtain the silicone-modified epoxy resin.

[0036] Preparation example 3 A silicone-modified epoxy resin is prepared by the following method: Mix 100 g of 3-hydroxypropyltrimethoxysilane, 200 g of epoxy resin (bisphenol A epoxy resin E-54), and 5 g of dibutyl nitrosamine, heat up to 130 °C for reaction, the vacuum degree of the reaction is 0.1 MPa, and react for 6 h to obtain the silicone-modified epoxy resin. Examples

[0037] Example 1 A silicone thermal conductive structural adhesive for power batteries over the full temperature range is prepared by the following method: S1. Mix 125 g of diluent (ethyl acetate), 60 g of methacrylate, and 100 g of organosilicon-modified epoxy resin and stir, then add 100 g of modified starch paste and stir to obtain mixture A; S2. Stir 400 g of polydimethylsiloxane and 200 g of filler (silica) evenly, then add mixture A and stir, then add 10 g of crosslinking agent (methyltrimethoxysilane) and 5 g of catalyst (chloroplatinic acid-dibutyl maleate complex) and stir to obtain the silicone thermal conductive structural adhesive for power batteries over the full temperature range.

[0038] The polydimethylsiloxane is vinyl-terminated polydimethylsiloxane. The molecular weight of the vinyl-terminated polydimethylsiloxane rubber is 500,000 g / mol, and the vinyl content in the vinyl-terminated polydimethylsiloxane is 0.1 mmol / g.

[0039] The average particle size of the silica is 50 nm.

[0040] The differences between Example 2 - 3 and Example 1 are that the types, dosages, and parameters of the raw materials for preparing the silicone thermal conductive structural adhesive for power batteries over the full temperature range are different. The specific differences are shown in Table 1: Table 1 Types, dosages, and parameters of the raw materials for preparing the silicone thermal conductive structural adhesive for power batteries in Examples 1 - 3 In Example 1, the modified starch was purchased from Jinan Zhuocai Chemical Co., Ltd., with a viscosity of 99 cps. Before use, 100 g of modified starch and 200 g of water were mixed and heated to 70 °C and stirred to obtain the modified starch paste.

[0041] In Example 2, the modified starch was purchased from Jinan Zhuocai Chemical Co., Ltd., with a viscosity of 99 cps. Before use, 80 g of modified starch and 240 g of water were mixed and heated to 70 °C and stirred to obtain the modified starch paste.

[0042] In Example 3, the modified starch was purchased from Jinan Zhuocai Chemical Co., Ltd., with a viscosity of 99 cps. Before use, 200 g of modified starch and 300 g of water were mixed and heated to 70 °C and stirred to obtain the modified starch paste.

[0043] Example 4 A silicone thermal conductive structural adhesive for power batteries over the full temperature range. The difference between this example and Example 1 is that the modified starch paste is prepared by the following method: 1) Mix 100 g of starch (corn starch) and 240 g of water, heat to 60 °C and stir to obtain a semi-paste; 2) Heat the semi-paste, 40 g of sodium alginate, 20 g of emulsifier (Tween), and 60 g of polyvinyl alcohol to 90 °C and stir evenly to obtain mixture A; 3) Mix mixture A and 10 g of boric acid solution evenly to obtain the modified starch paste.

[0044] The boric acid solution is obtained by mixing boric acid and water in a weight ratio of 2:8.

[0045] Example 5 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that the modified starch paste is prepared by the following method: 1) Mix 200 g of starch and 300 g of water, heat to 70 °C and stir to obtain a semi-paste; 2) Heat the semi-paste, 80 g of sodium alginate, 40 g of emulsifier (Tween), and 100 g of polyvinyl alcohol to 95 °C and stir evenly to obtain mixture A; 3) Mix mixture A and 20 g of boric acid solution evenly to obtain the modified starch paste.

[0046] The boric acid solution is obtained by mixing boric acid and water in a weight ratio of 3:8.

[0047] Example 6 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that the filler is pretreated through the following steps: Stir 150 g of filler (silica, average particle size of 50 nm), 40 g of carboxymethyl cellulose, and 200 g of water until the carboxymethyl cellulose is dissolved, then add 30 g of 3-allyloxypropyltrimethoxysilane, stir for 1.5 h, filter, and take the filter residue to obtain the pretreated filler.

[0048] Example 7 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 4 is that the filler is pretreated through the following steps: By weight, stir 200 g of filler (silica, average particle size of 50 nm), 80 g of carboxymethyl cellulose, and 250 g of water until the carboxymethyl cellulose is dissolved, then add 50 g of 3-allyloxypropyltrimethoxysilane, stir for 2 h, filter, and take the filter residue to obtain the pretreated filler.

[0049] Example 8 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that the average particle size of the silica includes 50 nm and 100 nm, and their weight ratio is 1:1.

[0050] Example 9 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that the average particle size of the silica is 100 nm.

[0051] Example 10 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 7 is that the average particle size of the silica includes 100 nm and 300 nm, and their weight ratio is 1:1.

[0052] Example 11 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that the cross-linking agent is obtained by mixing methyltriethoxysilane and vinyltriacetoxymethoxysilane in a weight ratio of 1:0.8.

[0053] Example 12 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 10 is that the cross-linking agent is obtained by mixing methyltriethoxysilane and vinyltriacetoxymethoxysilane in a weight ratio of 3:0.8.

[0054] Example 13 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that it is obtained by mixing methyltriethoxysilane and methyltriacetoxymethoxysilane in a weight ratio of 1:0.8.

[0055] Example 14 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this example and Example 1 is that the polydimethylsiloxane is hydroxyl-terminated polydimethylsiloxane.

[0056] The molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500000 g / mol.

[0057] Comparative example Comparative example 1 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this comparative example and Example 1 is that ethyl acrylate is used instead of methacrylate.

[0058] Comparative example 2 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this comparative example and Example 1 is that hydroxyethyl cellulose is used instead of modified starch.

[0059] Comparative example 3 A full-temperature-range silicone thermal conductive structural adhesive for power batteries. The difference between this comparative example and Example 1 is that bisphenol A epoxy resin E-20 is used instead of silicone-modified epoxy resin.

[0060] Detection method / Test method Adhesion test method: Test according to GBT 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)" (aluminum / aluminum).

[0061] Thermal conductivity test method: Refer to GB / T 10297-2015 "Determination of thermal conductivity of non-metallic solid materials".

[0062] Tensile strength and elongation at break: Test according to GBT 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0063] High and low temperature resistance test: After preparing samples by testing the all-temperature silicone thermal conductive structural adhesives for power batteries prepared in Examples 1-14 and Comparative Examples 1-3 according to GBT 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)" (aluminum / aluminum), place them in an environment of -40°C for 2h, and then place them in an environment of 350°C for 2h. This is one cycle. After 300 cycles, measure the adhesion force again. The experimental data are shown in Table 2: Table 2 Experimental data of Examples 1-14 and Comparative Examples 1-3 Comparing Example 1 with Comparative Examples 1-3, the adhesive force in Comparative Examples 1-3 is less than that in Example 1, and the change in adhesive force in Comparative Examples 1-3 after the high and low temperature resistance test is greater than that in Example 1; the thermal conductivity of Comparative Examples 1-3 is less than that in Example 1; the tensile strength and elongation at break of Comparative Examples 1-3 are also less than those in Example 1, indicating that by using methacrylate, organosilicon-modified epoxy resin and modified starch paste to prepare the all-temperature silicone thermal conductive structural adhesives for power batteries in the application, its bonding performance, high and low temperature resistance performance, thermal conductivity, tensile strength and elongation at break can be improved.

[0064] Comparing Example 1 with Examples 4-5, the adhesive force in Examples 4-5 is increased, and the change in adhesive force in Examples 4-5 after the high and low temperature resistance test is less than that in Example 1; the thermal conductivity of Examples 4-5 is greater than that in Example 1; the tensile strength and elongation at break of Examples 4-5 are also greater than those in Example 1, indicating that the modified starch paste prepared by this application can improve the bonding performance, high and low temperature resistance performance, thermal conductivity, tensile strength and elongation at break of the all-temperature silicone thermal conductive structural adhesives for power batteries.

[0065] Comparing Example 1 with Example 6, the adhesive force in Example 6 is increased, and after the high and low temperature resistance test, the change in the adhesive force of Example 6 is less than that of Example 1; the thermal conductivity of Example 6 is greater than that of Example 1; the tensile strength and elongation at break of Example 6 are also greater than those of Example 1. Comparing Example 4 with Example 7, the adhesive force in Example 7 is increased, and after the high and low temperature resistance test, the change in the adhesive force of Example 7 is less than that of Example 4; the thermal conductivity of Example 7 is greater than that of Example 4; the tensile strength of Example 7 is greater than that of Example 4. From Examples 1 and 6, 4 and 7, it can be seen that by pretreating the filler by the method in the present application, it is beneficial to improve the bonding performance, high and low temperature resistance performance, thermal conductivity and tensile strength of the full-temperature range silicone thermal conductive structural adhesive for power batteries.

[0066] Comparing Example 1 with Examples 8 - 9, the adhesive force in Example 8 is increased, and after the high and low temperature resistance test, the change in the adhesive force of Example 8 is less than those of Example 1 and 9; the thermal conductivity of Example 8 is greater than those of Example 1 and 9; the tensile strength of Example 8 is greater than those of Example 1 and 9. Comparing Example 7 with Example 10, the adhesive force in Example 10 is increased, and after the high and low temperature resistance test, the change in the adhesive force of Example 10 is less than that of Example 7; the thermal conductivity of Example 10 is greater than that of Example 7; the tensile strength of Example 10 is greater than that of Example 7. From Examples 1 and 8 - 9, 7 and 10, it can be seen that by optimizing the average particle size and dosage of the filler, it is beneficial to improve the bonding performance, high and low temperature resistance performance, thermal conductivity and tensile strength of the full-temperature range silicone thermal conductive structural adhesive for power batteries.

[0067] Comparing Example 1 with Examples 11 and 13, the adhesive force in Example 1 is increased, and after the high and low temperature resistance test, the change in the adhesive force of Example 1 is less than those of Example 11 and 13; the thermal conductivity of Example 1 is greater than those of Example 11 and 13; the tensile strength of Example 1 is greater than those of Example 11 and 13. Comparing Example 10 with Example 12, the adhesive force in Example 12 is increased, and after the high and low temperature resistance test, the change in the adhesive force of Example 12 is less than that of Example 10; the thermal conductivity of Example 12 is greater than that of Example 10; the tensile strength of Example 12 is greater than that of Example 10. From Examples 1 and 11, 13, 10 and 12, it can be seen that by optimizing the type and dosage of the crosslinking agent, it is beneficial to improve the bonding performance, high and low temperature resistance performance, thermal conductivity and tensile strength of the full-temperature range silicone thermal conductive structural adhesive for power batteries.

[0068] Comparing Example 1 with Example 14, the bonding strength is improved in Example 14, and the change in the bonding strength of Example 14 after the high and low temperature resistance test is less than that of Example 1; the thermal conductivity of Example 14 is greater than that of Example 1; the tensile strength of Example 14 is greater than that of Example 1, indicating that optimizing the type of polydimethylsiloxane is beneficial to improving the bonding performance, high and low temperature resistance performance, thermal conductivity and tensile strength of the silicone thermal conductive structural adhesive for power batteries in the full temperature range.

[0069] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A full-temperature range silicone thermal conductive structural adhesive for power batteries, characterized in that: Prepared from the following raw materials in weight percentage: Polydimethylsiloxane 40-45% Silicone modified epoxy resin 5-10% Methacrylate 3-6% Modified starch paste 5-10% Crosslinking agent 1-2% Filler 15-20% Catalyst 0.5-1% The rest is diluent The modified starch paste is obtained by mixing and gelatinizing the modified starch and water.

2. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 1, characterized in that: The modified starch paste is prepared by the following method: 1) Mix starch and water, heat to 60-70℃ and stir to obtain semi-gelatinized product; 2) The semi-gelatinized product, sodium alginate, emulsifier and polyvinyl alcohol are heated to 90-95°C and stirred to obtain a mixture A; 3) Mix the mixture A and the boric acid solution evenly to obtain a modified starch paste.

3. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 2, characterized in that: The weight parts of the modified starch paste are as follows: 5-10 parts starch 12-15 parts water 2-4 parts of sodium alginate Emulsifier 1-2 parts Polyvinyl alcohol 3-5 parts 0.5-1 part of boric acid solution.

4. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 3, characterized in that: The boric acid solution is obtained by mixing boric acid and water in a weight ratio of (2-3):

8.

5. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 1, characterized in that: The polydimethylsiloxane is vinyl-terminated polydimethylsiloxane, the molecular weight of the vinyl-terminated polydimethylsiloxane rubber is 500,000-1,000,000 g / mol, and the vinyl content in the vinyl-terminated polydimethylsiloxane is 0.1-0.3 mmol / g.

6. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 1, characterized in that: The organosilicon-modified epoxy resin is prepared by the following method: According to weight parts, 50-200 parts of 3-hydroxypropyltrimethoxysilane, 100-120 parts of epoxy resin and 3-5 parts of dibutylnitrosamine are mixed, and the temperature is raised to 125-130° C. for reaction, and the vacuum degree of the reaction is 0.06-0.1 MPa to obtain an organosilicon-modified epoxy resin.

7. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 1, characterized in that: The filler is pretreated by the following steps: According to weight parts, 15-20 parts of filler, 4-8 parts of carboxymethyl cellulose and 20-25 parts of water are stirred until the carboxymethyl cellulose is dissolved, and then 3-5 parts of 3-propyleneoxypropyltrimethoxysilane are added, stirred, filtered, and the filter residue is taken to obtain a pretreated filler.

8. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 1, characterized in that: The average particle size of the filler includes 50-100 nm and 100-300 nm.

9. The full-temperature range silicone thermal conductive structural adhesive for power batteries according to claim 1, characterized in that: The crosslinking agent is at least one of methyltrimethoxysilane, methyltributylanoximesilane, vinyltributylanoximesilane, methyltriethoxysilane or vinyltrimethoxysilane.

10. A method for preparing the full-temperature range silicone thermal conductive structural adhesive for power batteries according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: S1, mixing a diluent, methacrylate and silicone-modified epoxy resin, and then adding modified starch paste and stirring to obtain a mixture A; S2. Evenly stir the polydimethylsiloxane and filler, then add the mixture A and stir, then add the cross-linking agent and the catalyst and stir to obtain a full-temperature range silicone thermal conductive structural adhesive for power batteries.

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