Flame-retardant heat-conducting structural adhesive for automobile power battery pack and preparation method of flame-retardant heat-conducting structural adhesive

Abstract

The invention discloses a flame-retardant heat-conducting structural adhesive for an automobile power battery pack and a preparation method of the flame-retardant heat-conducting structural adhesive, and belongs to the technical field of structural adhesives, the structural adhesive is composed of a component A and a component B. The component A comprises the following raw materials: epoxy resin, a flexibilizer, a diluent, a heat-conducting filler, a flame retardant, a coupling agent and a thixotropic agent; the component B comprises the following raw materials in parts by weight: a curing agent, a heat-conducting filler, a flame retardant, a coupling agent and a thixotropic agent; the heat-conducting filler in the component A and the component B is composed of a flaky filler, a spherical filler and a fine powder filler, the particle size D50 of the flaky filler is 7-15 [mu] m, the particle size D50 of the spherical filler is 3-8 [mu] m, and the particle size D50 of the fine powder filler is 0.3-2 [mu] m. The problems of high viscosity and low strength of the structural adhesive due to the addition of a large amount of inorganic filler are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of structural adhesive technology, and in particular to a flame-retardant and thermally conductive structural adhesive for automotive power battery packs and its preparation method. Background Technology

[0002] In the process of industrial production and technological development, thermally conductive structural adhesives, as a special type of adhesive, play an important role in many fields due to their excellent thermal conductivity and structural bonding strength. Especially in cutting-edge fields such as new energy power batteries and electronic heat dissipation, with the continuous improvement of equipment performance and increasingly stringent requirements for heat dissipation and mechanical fixation, the application of thermally conductive structural adhesives is becoming increasingly widespread, greatly promoting the development of related industries and providing strong support for improving equipment stability and performance.

[0003] In the past, to achieve high thermal conductivity in structural adhesives, the industry typically added a large amount of inorganic fillers to the adhesive matrix. This is because inorganic fillers have excellent thermal conductivity, and increasing their content in the adhesive can effectively improve the overall thermal conductivity. Simultaneously, to impart flame-retardant properties to structural adhesives, flame-retardant powders are often added to the structural adhesive system, thus producing flame-retardant and thermally conductive structural adhesives. These conventional methods, to a certain extent, meet the needs of some application scenarios requiring both thermal conductivity and flame retardancy.

[0004] However, this conventional technique has significant drawbacks. The addition of large amounts of inorganic fillers leads to a substantial increase in adhesive viscosity and a marked increase in the hardness of the cured product. This makes the structural adhesive prone to settling, resulting in difficulties in dispensing during construction (dispensing becomes particularly difficult when the viscosity of the structural adhesive exceeds 60,000 mPa·s). Furthermore, the strength and toughness of the structural adhesive decrease significantly, making it prone to cracking after thermal cycling, thus failing to meet the performance requirements of some applications. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a flame-retardant thermally conductive structural adhesive for automotive power battery packs and its preparation method. This application effectively solves the problems of high viscosity and low strength caused by the large addition of inorganic fillers in structural adhesives by screening the particle size and shape of thermally conductive fillers.

[0006] The present invention provides a flame-retardant and thermally conductive structural adhesive for automotive power battery packs and its preparation method, which adopts the following technical solution:

[0007] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs is composed of component A and component B in a weight ratio of 1:1. Component A includes the following raw materials in parts by weight: 50-90 parts epoxy resin, 10-30 parts toughening agent, 2-5 parts diluent, 15-25 parts thermally conductive filler, 10-20 parts flame retardant, 1-3 parts coupling agent, and 0.5-2 parts thixotropic agent.

[0008] Component B comprises the following raw materials in parts by weight: 50-100 parts curing agent, 15-25 parts thermally conductive filler, 5-10 parts flame retardant, 1-3 parts coupling agent, and 0.5-2 parts thixotropic agent.

[0009] The thermally conductive fillers in components A and B are composed of sheet-like fillers, spherical fillers, and fine powder fillers. The particle size D50 of the sheet-like fillers is 7-15 μm, the particle size D50 of the spherical fillers is 3-8 μm, and the particle size D50 of the fine powder fillers is 0.3-2 μm.

[0010] By adopting the above technical solution and selecting thermally conductive fillers of different particle sizes and shapes, a densely packed structure can be formed between the fillers, constructing an effective thermally conductive pathway with a low addition amount, thus achieving high thermal conductivity. This is because the sheet-like fillers, as the main thermally conductive framework, overlap with each other to form a continuous thermally conductive pathway, ensuring the high thermal conductivity of the system and fulfilling the core role of "paving the way." The spherical fillers can accurately fill the large gaps formed by the overlap of the sheet-like fillers, eliminating voids in the thermally conductive pathway, improving the continuity of thermal conductivity, and at the same time avoiding excessive resin aggregation at the gaps, thus achieving the densification effect of "filling the pores." The fine powder fillers further fill the micro-gaps between the spherical and sheet-like fillers, completing the densification of the entire filler system, making the contact between filler particles closer, reducing the shear resistance between particles, and lowering the viscosity of the system. In addition, spherical fillers and fine powder fillers have the characteristic of low surface area. Compared with sheet-like or irregular fillers of the same particle size, they can significantly reduce the interfacial contact area with the epoxy resin matrix, reduce the interfacial frictional resistance between the filler and the resin, thereby improving the problems of easy sedimentation and difficult dispensing of structural adhesives, while also ensuring that structural adhesives have good strength and toughness.

[0011] In a preferred embodiment, the weight ratio of the sheet-like packing, the spherical packing, and the fine powder packing is (5-6):(2-3):2.

[0012] By adopting the above technical solution, when the proportions of sheet filler, spherical filler and fine powder filler are within this range, good gradation and filling among the three fillers can be achieved. This effectively solves the problems of easy settling and difficult application of structural adhesive caused by adding a large amount of inorganic filler, improves the construction performance of structural adhesive, maintains the strength and toughness of structural adhesive, and reduces the risk of cracking after thermal cycling.

[0013] In a preferred embodiment, the sheet-like filler is one of sheet-like boron nitride, sheet-like silicon carbide, and flake graphite; the spherical filler is one of spherical alumina and spherical aluminum nitride; and the fine powder filler is one of fine powder magnesium oxide, fine powder alumina, and fine powder graphene.

[0014] In a preferred embodiment, the epoxy resin comprises bisphenol A epoxy resin and DOPO modified epoxy resin in a weight ratio of 11:3.

[0015] In a preferred embodiment, the DOPO-modified epoxy resin is obtained by the following preparation method: first, the epoxy resin is heated to 130-135°C, and after activation by adding a catalyst, DOPO powder is added under stirring, and the reaction is carried out at 130-135°C for 3 hours to obtain the DOPO-modified epoxy resin.

[0016] In a preferred embodiment, the phosphorus content in the DOPO modified epoxy resin is 1.5%.

[0017] By adopting the above technical solution, DOPO is introduced into epoxy resin in a covalent manner, which improves the flame retardant effect of the structural adhesive, avoids the addition of large doses of flame retardant, and does not affect the viscosity of the structural adhesive.

[0018] In a preferred embodiment, the toughening agent is composed of a core-shell rubber modified epoxy resin and a CTBN modified epoxy resin in a weight ratio of 2:1.

[0019] In a preferred embodiment, the thixotropic agents in both component A and component B are one of fumed silica, organobentonite, hydrogenated castor oil, and polyamide wax.

[0020] More preferably, the curing agent is one or more of the following: modified polyamide, modified aliphatic amine, modified phenolic amine, modified aromatic amine, and modified cycloaliphatic amine.

[0021] In a preferred embodiment, the coupling agent in both component A and component B is one or more of vinylsilane, aminosilane, epoxysilane, mercaptosilane, and methacryloxysilane.

[0022] A second aspect of the present invention is to provide a method for preparing the flame-retardant and thermally conductive structural adhesive for automotive power battery packs, comprising the following steps:

[0023] Preparation of Component A: Epoxy resin, toughening agent, diluent, and coupling agent are stirred and mixed evenly, and then thermally conductive filler, flame retardant, and thixotropic agent are added in sequence, stirred evenly, and vacuumed to obtain Component A;

[0024] Preparation of Component B: After the curing agent and coupling agent are stirred and mixed evenly, thermally conductive filler, flame retardant and thixotropic agent are added and stirred evenly, and then vacuum is applied to obtain Component B; Component A and Component B are mixed at a weight ratio of 1:1 to obtain flame-retardant thermally conductive structural adhesive.

[0025] In summary, the present invention has the following beneficial effects:

[0026] The thermally conductive fillers in components A and B are composed of flake, spherical, and fine powder fillers with different particle sizes. This avoids the drawbacks of adding large amounts of inorganic fillers, prevents a significant increase in adhesive viscosity and a significant increase in cured product hardness, solves the problems of easy settling and difficult application of structural adhesives, improves construction convenience, and can also improve the strength and toughness of structural adhesives, reducing cracking after thermal cycling. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to embodiments. All details not specifically stated herein are based on conventional conditions or conditions recommended by the manufacturer. All reagents and instruments, unless otherwise stated below, are commercially available conventional reagent products.

[0028] The core-shell rubber content in the core-shell rubber modified epoxy resin is 40%.

[0029] The CTBN content in the CTBN-modified epoxy resin is 20%.

[0030] Modified polyamide with an active hydrogen equivalent of 180 g / eq;

[0031] Modified aromatic amine with an active hydrogen equivalent of 37 g / eq;

[0032] Modified fatty amine with an active hydrogen equivalent of 50 g / eq.

[0033] Preparation Example 1

[0034] The preparation method of DOPO modified epoxy resin includes the following steps: Calculated based on a target phosphorus content of 1.5%, the epoxy resin is first heated to 130℃, and after adding the catalyst triphenylphosphine for activation for 10 min, DOPO powder is added under stirring. After reacting at 130℃ for 3 h, a clear and transparent DOPO modified epoxy resin is obtained, which is then cooled for later use.

[0035] The specific calculations are as follows: DOPO has a molecular weight of 216.6 g / mol and a phosphorus atomic weight of 31 g / mol. The phosphorus mass fraction in DOPO is 31 / 216.6≈14.34%. Taking 100g of epoxy resin as an example, the amount of DOPO used is (1.5%×100) / 14.34%≈10.5g, and the amount of triphenylphosphine used is 1% of the weight of epoxy resin.

[0036] Example 1

[0037] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs includes component A and component B. Component A includes the following raw materials: 5 kg epoxy resin, 1 kg toughening agent, 0.2 kg diglycidyl ether, 1.5 kg thermally conductive filler, 1 kg magnesium hydroxide, 0.1 kg vinyltrimethoxysilane, and 0.05 kg organobentonite.

[0038] Component B comprises the following raw materials: 5 kg curing agent, 1.5 kg thermally conductive filler, 0.5 kg magnesium hydroxide, 0.1 kg vinyltrimethoxysilane, and 0.05 kg organobentonite;

[0039] Both component A and component B contain thermally conductive fillers composed of sheet-like fillers, spherical fillers, and fine powder fillers in a weight ratio of 5:3:2. The sheet-like fillers are made of sheet-like boron nitride with a particle size D50 of 8 μm, the spherical fillers are made of spherical alumina with a particle size D50 of 3 μm, and the fine powder fillers are made of fine powder alumina with a particle size D50 of 0.5 μm.

[0040] The epoxy resin includes bisphenol A epoxy resin in a weight ratio of 11:3 and DOPO modified epoxy resin obtained in Preparation Example 1.

[0041] The toughening agent is composed of core-shell rubber modified epoxy resin and CTBN modified epoxy resin in a weight ratio of 2:1.

[0042] The curing agent is composed of modified polyamide, modified aromatic amine, and modified aliphatic amine in a weight ratio of 12:3:4;

[0043] Its preparation method includes the following steps:

[0044] Preparation of Component A: Epoxy resin, toughening agent, diglycidyl ether, and vinyltrimethoxysilane are stirred and mixed evenly, and then thermally conductive filler, magnesium hydroxide, and organic bentonite are added in sequence, stirred evenly, and vacuumed to obtain Component A.

[0045] Preparation of component B: After the curing agent and vinyltrimethoxysilane are mixed evenly, thermally conductive filler, magnesium hydroxide and organic bentonite are added, mixed evenly, and then vacuumed to obtain component B.

[0046] Flame-retardant and thermally conductive structural adhesive was prepared by mixing component A and component B in a weight ratio of 1:1.

[0047] Example 2

[0048] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs includes component A and component B. Component A includes the following raw materials: 7 kg epoxy resin, 2 kg toughening agent, 0.3 kg diglycidyl ether, 2 kg thermally conductive filler, 1.5 kg aluminum hydroxide, 0.2 kg vinyltrimethoxysilane, and 0.1 kg organobentonite.

[0049] Component B comprises the following raw materials: 8 kg curing agent, 2 kg thermally conductive filler, 0.8 kg aluminum hydroxide, 0.2 kg vinyltrimethoxysilane, and 0.1 kg organobentonite;

[0050] Both the thermally conductive fillers in component A and component B are composed of sheet fillers, spherical fillers and fine powder fillers in a weight ratio of 5:3:2. The sheet fillers are sheet-shaped silicon nitride with a particle size D50 of 10μm, the spherical fillers are spherical aluminum nitride with a particle size D50 of 6μm, and the fine powder fillers are fine powder magnesium oxide with a particle size D50 of 1μm.

[0051] The epoxy resin includes bisphenol A epoxy resin in a weight ratio of 11:3 and DOPO modified epoxy resin obtained in Preparation Example 1.

[0052] The toughening agent is composed of core-shell rubber modified epoxy resin and CTBN modified epoxy resin in a weight ratio of 2:1.

[0053] The curing agent is composed of modified polyamide, modified aromatic amine, and modified aliphatic amine in a weight ratio of 12:3:4;

[0054] Its preparation method includes the following steps:

[0055] Preparation of Component A: Epoxy resin, toughening agent, diglycidyl ether, and vinyltrimethoxysilane are stirred and mixed evenly, and then thermally conductive filler, aluminum hydroxide, and organobentonite are added in sequence, stirred evenly, and vacuumed to obtain Component A.

[0056] Preparation of component B: After the curing agent and vinyltrimethoxysilane are mixed evenly, thermally conductive filler, aluminum hydroxide and organobentonite are added, mixed evenly, and then vacuumed to obtain component B;

[0057] Flame-retardant and thermally conductive structural adhesive was prepared by mixing component A and component B in a weight ratio of 1:1.

[0058] Example 3

[0059] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs includes component A and component B. Component A includes the following raw materials: 9 kg of epoxy resin, 3 kg of toughening agent, 0.5 kg of diglycidyl ether, 2.5 kg of thermally conductive filler, 2 kg of antimony trioxide, 0.3 kg of vinyltrimethoxysilane, and 0.2 kg of organobentonite.

[0060] Component B comprises the following raw materials: 10 kg curing agent, 2.5 kg thermally conductive filler, 1 kg antimony trioxide, 0.3 kg vinyltrimethoxysilane, and 0.2 kg organobentonite;

[0061] Both the thermally conductive fillers in component A and component B are composed of sheet fillers, spherical fillers and fine powder fillers in a weight ratio of 5:3:2. The sheet fillers are flake graphite with a particle size D50 of 15μm, the spherical fillers are spherical alumina with a particle size D50 of 8μm, and the fine powder fillers are fine powder graphene with a particle size D50 of 2μm.

[0062] The epoxy resin includes bisphenol A epoxy resin in a weight ratio of 11:3 and DOPO modified epoxy resin obtained in Preparation Example 1.

[0063] The toughening agent is composed of core-shell rubber modified epoxy resin and CTBN modified epoxy resin in a weight ratio of 2:1.

[0064] The curing agent is composed of modified polyamide, modified aromatic amine, and modified aliphatic amine in a weight ratio of 12:3:4;

[0065] Its preparation method includes the following steps:

[0066] Preparation of Component A: Epoxy resin, toughening agent, diglycidyl ether, and vinyltrimethoxysilane are stirred and mixed evenly, and then thermally conductive filler, antimony trioxide, and organobentonite are added in sequence, stirred evenly, and vacuumed to obtain Component A.

[0067] Preparation of component B: After the curing agent and vinyltrimethoxysilane are mixed evenly, thermally conductive filler, antimony trioxide and organobentonite are added, mixed evenly, and then vacuumed to obtain component B.

[0068] Flame-retardant and thermally conductive structural adhesive was prepared by mixing component A and component B in a weight ratio of 1:1.

[0069] Example 4

[0070] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the weight ratio of sheet filler, spherical filler, and fine powder filler in components A and B is 6:2:2, while all other aspects are the same as in Example 2.

[0071] Comparative Example 1

[0072] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that it does not contain DOPO modified epoxy resin, and the amount of bisphenol A epoxy resin used is 7 kg. All other aspects are the same as in Example 2.

[0073] Comparative Example 2

[0074] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the thermally conductive fillers in components A and B are 1.5 kg of irregularly shaped alumina with a particle size D50 of 20 μm and D90 of 30 μm, and 0.5 kg of spherical magnesium oxide with a particle size D50 of 25 μm and D90 of 34 μm. All other aspects are the same as in Example 2.

[0075] Comparative Example 3

[0076] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the amount of thermally conductive filler in both component A and component B is 5 kg, of which 2.5 kg is irregularly shaped alumina with a particle size D50 of 20 μm and D90 of 30 μm; and 2.5 kg is spherical magnesium oxide with a particle size D50 of 25 μm and D90 of 34 μm. All other aspects are the same as in Example 2.

[0077] Comparative Example 4

[0078] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the thermally conductive filler is composed only of sheet filler and spherical filler in a weight ratio of 5:3, while all other aspects are the same as in Example 2.

[0079] Comparative Example 5

[0080] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the thermally conductive filler is composed only of sheet filler and fine powder filler in a weight ratio of 5:2, while all other aspects are the same as in Example 2.

[0081] Comparative Example 6

[0082] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the weight ratio of sheet filler, spherical filler, and fine powder filler is 7:1:2, while all other aspects are the same as in Example 2.

[0083] Comparative Example 7

[0084] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the weight ratio of sheet filler, spherical filler, and fine powder filler is 4:4:2, while all other aspects are the same as in Example 2.

[0085] Comparative Example 8

[0086] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the particle size D50 of the sheet filler is 20 μm, the particle size D50 of the spherical filler is 12 μm, and the particle size D50 of the fine powder filler is 5 μm; all other aspects are the same as in Example 2.

[0087] Comparative Example 9

[0088] A flame-retardant and thermally conductive structural adhesive for automotive power battery packs differs from Example 2 in that the particle size D50 of the sheet filler is 20 μm, the particle size D50 of the spherical filler is 1 μm, and the particle size D50 of the fine powder filler is 0.1 μm; all other aspects are the same as in Example 2.

[0089] Performance testing

[0090] The viscosity, shear strength, thermal cycling shear strength, thermal conductivity, flame retardancy rating, and flame retardancy rating after damp heat aging of the flame-retardant and thermally conductive structural adhesives obtained in the above embodiments and comparative examples were tested. The test results are shown in the table below.

[0091] Viscosity was measured in accordance with the provisions of GB / T2794-2022, using a single-tube rotational viscometer method.

[0092] Shear strength was tested by preparing tensile shear samples according to the specifications in GB / T7124-2008. The samples were cured at room temperature for 7 days. After curing, the samples were subjected to thermal cycling tests. The test cycle was as follows: after placing the samples at -40℃ for 2 hours, they were placed at 150℃ for 2 hours as one cycle. After 500 cycles, the shear strength was tested.

[0093] Thermal conductivity was tested according to the specifications in ASTM D5470.

[0094] The damp heat aging conditions in the flame retardant performance test are as follows: after being placed at 40℃ and 95% relative humidity for 28 days, the flame retardant rating is tested.

[0095] Table 1. Performance Test Results of Flame-Retardant and Thermally Conductive Structural Adhesive

[0096]

[0097] Based on the test data in Table 1:

[0098] The thermally conductive structural adhesives obtained in Examples 1-4 of this application have a viscosity ≤50000mPa·s, exhibiting good workability. Furthermore, the thermally conductive structural adhesives obtained in this application have good initial shear strength, and after thermal cycling, the shear strength remains above 80%, without cracking. In addition, even after reducing the amount of flame retardant, the thermally conductive gel still exhibits excellent flame retardant properties.

[0099] Compared with Example 2, when DOPO modified epoxy resin was missing from the raw materials, the flame retardant properties of the thermally conductive structural adhesive obtained in Comparative Example 1 were greatly reduced, and the shear strength of the structural adhesive was also significantly reduced. It can be seen that after DOPO modified epoxy resin replaced part of the epoxy resin, the flame retardant properties of the structural adhesive were improved, and the structural adhesive also had good shear strength.

[0100] Compared with Example 2, when aluminum oxide and magnesium oxide were used to replace the sheet filler, spherical filler and fine powder filler of this application, the shear strength and thermal conductivity of the thermally conductive structural adhesive obtained in Comparative Example 2 were significantly reduced compared with Example 2. This further illustrates that the combination of fillers in this application effectively improves the thermal conductivity and strength of the thermally conductive structural adhesive.

[0101] Compared with Example 2, when aluminum oxide and magnesium oxide were used to replace the sheet filler, spherical filler and fine powder filler of this application, and the amount of aluminum oxide and magnesium oxide was increased, the strength of the structural adhesive obtained in Comparative Example 3 was significantly reduced. Although the thermal conductivity increased, it was much lower than that in Example 2 of this application. Moreover, the addition of a large amount of filler caused the viscosity of the structural adhesive to increase significantly, which affected the performance of the structural adhesive.

[0102] Compared with Example 2, when only two of the following thermally conductive fillers were used in Comparative Examples 4-5, the strength of the thermally conductive structural adhesive obtained in Comparative Examples 4-5 was significantly reduced, indicating that the combination of the three fillers effectively improved the strength of the thermally conductive structural adhesive.

[0103] Compared with Example 2, in Comparative Examples 6-7, when the proportions of the three thermally conductive fillers are not within the range of this application, the strength and thermal conductivity of the thermally conductive structural adhesive are affected to varying degrees. It can be seen that when the proportions of the three are within the range of this application, the various properties of the thermally conductive structural adhesive can reach a better state.

[0104] Compared with Example 2, when the particle sizes of the sheet filler, spherical filler, and fine powder filler are all large, the viscosity of the thermally conductive structural adhesive decreases. Although the workability is good, the initial and shear strength after thermal cycling are significantly lower than the shear strength in Example 2. Furthermore, the flame retardancy rating of the structural adhesive after hygrothermal aging is also significantly lower than that in Example 2. This is because as the particle size increases, the physical anchoring effect between the filler and the resin matrix weakens. Large-diameter fillers are more likely to become stress concentration points when under stress, resulting in relatively weak interfacial bonding and reduced strength of the structural adhesive. In addition, the increased porosity between large particles increases interfacial thermal resistance and reduces thermal conductivity.

[0105] Compared with Example 2, when the particle size of the flake filler is larger and the particle size of the spherical and fine powder fillers is smaller, the shear strength and thermal conductivity of Comparative Example 9 are basically close to those of Example 2, but the viscosity increases significantly, affecting the performance of the structural adhesive.

[0106] The embodiments described herein are merely illustrative of preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A flame-retardant and thermally conductive structural adhesive for automotive power battery packs, comprising component A and component B in a weight ratio of 1:1, characterized in that: Component A comprises the following raw materials in parts by weight: 50-90 parts epoxy resin, 10-30 parts toughening agent, 2-5 parts diluent, 15-25 parts thermally conductive filler, 10-20 parts flame retardant, 1-3 parts coupling agent, and 0.5-2 parts thixotropic agent. Component B comprises the following raw materials in parts by weight: 50-100 parts curing agent, 15-25 parts thermally conductive filler, 5-10 parts flame retardant, 1-3 parts coupling agent, and 0.5-2 parts thixotropic agent. The thermally conductive fillers in components A and B are composed of sheet-like fillers, spherical fillers, and fine powder fillers. The particle size D50 of the sheet-like fillers is 7-15 μm, the particle size D50 of the spherical fillers is 3-8 μm, and the particle size D50 of the fine powder fillers is 0.3-2 μm.

2. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 1, characterized in that: The weight ratio of the sheet-like packing, spherical packing, and fine powder packing is (5-6):(2-3):

2.

3. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 1, characterized in that: The sheet-like filler is one of sheet-like boron nitride, sheet-like silicon carbide, and flake graphite; The spherical filler is one of spherical alumina or spherical aluminum nitride; The fine powder filler is one of fine powder magnesium oxide, fine powder aluminum oxide, or fine powder graphene.

4. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 1, characterized in that: The epoxy resin comprises bisphenol A epoxy resin and DOPO modified epoxy resin in a weight ratio of 11:

3.

5. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 4, characterized in that: The DOPO-modified epoxy resin is obtained by the following preparation method: first, the epoxy resin is heated to 130-135℃, and after activation by adding a catalyst, DOPO powder is added under stirring, and the reaction is carried out at 130-135℃ for 3 hours to obtain the DOPO-modified epoxy resin.

6. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 5, characterized in that: The phosphorus content in the DOPO modified epoxy resin is 1.5%.

7. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 1, characterized in that: The toughening agent is composed of core-shell rubber modified epoxy resin and CTBN modified epoxy resin in a weight ratio of 2:

1.

8. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 1, characterized in that: The thixotropic agents in components A and B are all selected from fumed silica, organobentonite, hydrogenated castor oil, and polyamide wax.

9. The flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to claim 1, characterized in that: The coupling agents in components A and B are one or more of vinylsilane, aminosilane, epoxysilane, mercaptosilane, and methacryloxysilane.

10. A method for preparing a flame-retardant and thermally conductive structural adhesive for automotive power battery packs according to any one of claims 1-9, characterized in that: Includes the following steps: Preparation of Component A: Epoxy resin, toughening agent, diluent, and coupling agent are stirred and mixed evenly, and then thermally conductive filler, flame retardant, and thixotropic agent are added in sequence, stirred evenly, and vacuumed to obtain Component A; Preparation of Component B: After the curing agent and coupling agent are stirred and mixed evenly, thermally conductive filler, flame retardant and thixotropic agent are added, stirred evenly and then vacuumed to obtain Component B; The flame-retardant and thermally conductive structural adhesive is obtained by mixing component A and component B in a weight ratio of 1:1.

Images