A packaging adhesive and a method for preparing the same

Abstract

This invention belongs to the field of adhesive technology, and relates to an encapsulation adhesive and its preparation method. Component A of the encapsulation adhesive comprises 50-85 parts of trimethoxysilane-terminated polyether, 5-10 parts of epoxy curing agent, 1-5 parts of coupling agent, 1-3 parts of dehydrating agent, and 15-40 parts of filler; Component B comprises 45-85 parts of polyurethane-modified epoxy resin, 10-30 parts of plasticizer, 0.5-3 parts of catalyst, 1-3 parts of water, and 15-45 parts of filler; the mass ratio of component A to component B is 1:(0.8-1.2). The encapsulation adhesive of this invention has excellent temperature resistance, good colloidal flexibility, low modulus at low temperatures, and excellent aging performance. After mixing and curing components A and B, a cured body with excellent sealing performance, good airtightness, and good adaptability to substrates is formed, making it an encapsulation material that provides long-term comprehensive protection for power batteries. Components A and B are free of volatiles and have low odor, which is beneficial to the usage environment and operators.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, and particularly relates to an encapsulating adhesive and its preparation method. Background Technology

[0002] In recent years, my country's new energy vehicle industry has developed rapidly, giving rise to a large number of models that are popular with consumers both domestically and internationally due to their high quality, advanced technology, and excellent user experience. In 2023, my country's production and sales of new energy vehicles reached 9.587 million and 9.495 million units respectively, representing year-on-year increases of 35.8% and 37.9%. For nine consecutive years, China has ranked first globally in both production and sales, with sales accounting for 31.6% of total vehicle sales. New energy electric vehicles represent a mainstream development trend for addressing energy, environmental, and urban transportation issues, and are also a major direction for the future development of the automotive manufacturing industry.

[0003] Power storage batteries are a core component of new energy vehicles, determining their safety, lifespan, and performance. They are also among the most expensive components, accounting for over 50% of the total vehicle cost. As a crucial material in battery assembly, adhesives play a vital role in automotive power batteries, profoundly impacting their output efficiency, charging speed, heat dissipation, and safety. Currently, the electrification wave is sweeping the globe, leading to an explosive growth in demand for power batteries, and consequently, a corresponding expansion of the adhesive market.

[0004] Power battery technology is undergoing rapid iteration and upgrading, with new products constantly emerging. Developing new adhesive materials to adapt to these advancements is indispensable for improving the energy density, safety, cycle life, and lightweight design of power batteries. Adhesives play four main roles in power batteries: first, providing protection; second, enabling safe and reliable lightweight design; third, thermal management; and fourth, helping batteries cope with more complex operating environments.

[0005] In the new energy vehicle sector, adhesive products are primarily used in various scenarios such as protection, thermal conductivity, and bonding of power battery management systems (BMS) and similar new energy storage battery modules. These products are also applied in the thermal management system of battery packs, serving functions of heat conduction, potting, and protection. The entry of adhesives into the power battery pack industry requires a comprehensive approach, considering factors such as impact and shock resistance, flame retardancy, thermal conductivity, and waterproofing, to provide customers with the most reliable solutions and ensure the safety and reliability of power batteries.

[0006] Currently, the structural adhesives for power battery packs, especially PACK encapsulation adhesives, are mainly polyurethane structural adhesives. Polyurethane structural adhesives have good elasticity and tensile strength, excellent shock resistance, and are also wear-resistant, cold-resistant, and oil-resistant. However, polyurethane structural adhesives have poor resistance to humid heat aging, poor high-temperature resistance, and reduced flexibility at low temperatures, which seriously affects the use of batteries under high and low temperature conditions. At the same time, polyurethane structural adhesives contain free NCO, which is not environmentally friendly. Therefore, developing a power battery PACK encapsulation adhesive with excellent bonding performance, low low-temperature modulus, and environmental friendliness has become an urgent task in the field of new energy battery adhesives. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a power battery pack encapsulation adhesive and its preparation method. The specific technical solution is as follows:

[0008] The first object of the present invention is to provide an encapsulating adhesive comprising component A and component B:

[0009] Component A, by weight, includes the following components:

[0010] 50-85 parts of trimethoxysilane-terminated polyether, 5-10 parts of epoxy curing agent, 1-5 parts of coupling agent, 1-3 parts of dehydrating agent, and 15-40 parts of filler.

[0011] The structural formula of the trimethoxysilane-terminated polyether is shown in Formula (I):

[0012]

[0013] Where n = 20 - 40;

[0014] Component B, by weight, includes the following components:

[0015] The composition includes 45-85 parts polyurethane-modified epoxy resin, 10-30 parts plasticizer, 0.5-3 parts catalyst, 1-3 parts water, and 15-45 parts filler.

[0016] The mass ratio of component A to component B is 1:(0.8-1.2).

[0017] The trimethoxy-modified silane-terminated polyether in component A of the encapsulating adhesive of this invention has a main chain structure composed of silane-terminated polyether units and polyurethane structural units, achieving good flexibility. Compared with traditional rubber-modified or ethylene oxide-modified flexible epoxy resins, it has higher elongation, lower elastic modulus, higher impact resistance and heat resistance, and good compatibility with other epoxy resins. The structure of four (-CH2-) bonds in two ether bonds, when the number of (-CH2-) in the molecular chain is even, the material has better crystallinity, resulting in strong intermolecular attraction and tight molecular arrangement.

[0018] This invention modifies epoxy resin by blending trimethoxy-modified silane-terminated polyether of formula (I) with epoxy resin. The epoxy resin and trimethoxy-modified silane-terminated polyether form an interpenetrating network structure, which forms an island structure after curing. This retains the bonding strength of epoxy resin to metal and plastic substrates, while increasing the toughness and tensile properties of the adhesive material. It effectively combines the advantages of epoxy resin and silane-modified polyether, overcoming the limitations of traditional adhesives.

[0019] Furthermore, the preparation method of the trimethoxysilane-terminated polyether is as follows:

[0020] At room temperature, heat polytetrahydrofuran diol (PTMG) to 30-50℃ and stir at a constant temperature until it becomes a homogeneous, lump-free liquid. Then, raise the temperature to 110-120℃, stir under vacuum for 1-3 hours, and then lower the temperature to 50-70℃. Add a silane coupling agent containing NCO, then raise the temperature to 75-90℃, stir under vacuum for 1-3 hours, and then stop the reaction and discharge the material.

[0021] This invention relates to the polymerization of tetrahydrofuran diol with a silane coupling agent containing NCO to form the trimethoxysilane-terminated polyether. Tetrahydrofuran diol, as a polyether, possesses excellent flexibility. Polyethers prepared using tetrahydrofuran diol as the soft segment exhibit advantages such as good toughness, solvent resistance, and hydrolysis resistance. Furthermore, the glass transition temperature of tetrahydrofuran diol can be as low as -70°C, and the silane-modified polyether obtained by polymerizing tetrahydrofuran diol with an NCO-containing silane coupling agent exhibits excellent low-temperature resistance.

[0022] Furthermore, the relative molecular mass of the polytetrahydrofuran diol is 2000 (PTMG2000); the silane coupling agent is 3-isocyanate-propyltrimethoxysilane.

[0023] The reaction equation is as follows:

[0024]

[0025] Furthermore, the epoxy curing agent is one or more of polyetheramine D2000, polyetheramine D400, and polyetheramine D230.

[0026] The epoxy curing agent of this invention is a polyetheramine curing agent with a polyether structure as its main chain. It has good flexibility and is a flexible epoxy curing agent. It has good compatibility with epoxy resin. The cured body has excellent toughness and fatigue resistance, good water resistance and heat resistance, and can be used for a long time in humid and high temperature environments. At the same time, it is not easy to age or break.

[0027] Further, the coupling agent is one or more of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and aminopropyltriethoxysilane.

[0028] Furthermore, the dehydrating agent is vinyltrimethoxysilane.

[0029] Furthermore, the epoxy equivalent of the polyurethane-modified epoxy resin is between 600-900 g / eq, and its structural formula is shown in formula (II):

[0030]

[0031] Where R is CH3; m = 2-5, n = 1-4.

[0032] Furthermore, the plasticizer is polypropylene glycol 2000; it can improve the flexibility and ductility of the cured toughener, and its presence can also improve the adhesion and durability of the adhesive to plastics and metals.

[0033] Furthermore, the catalyst is one or more of dibutyltin dilaurate, chelated tin, and bismuth titanate; the water is self-made deionized water.

[0034] Furthermore, the filler is nano-calcium carbonate treated with a silane coupling agent, and the specific method is as follows:

[0035] The nano-calcium carbonate powder is heated to 70-120℃, and then an atomized silane coupling agent is sprayed onto the nano-calcium carbonate powder while stirring. After spraying is completed, it is placed in an oven to dry for later use. The mass of the silane coupling agent is 0.5-3% of the nano-calcium carbonate powder. The silane coupling agent is KH550, KH560, or similar silane coupling agents.

[0036] A second objective of this invention is to provide a method for preparing the above-mentioned encapsulating adhesive, comprising the following steps:

[0037] (1) Preparation of component A:

[0038] A1: Add trimethoxysilane-terminated polyether, epoxy curing agent, filler, and coupling agent to the reaction vessel and stir under vacuum at 20-30℃ for 1-3 hours;

[0039] A2: Continue to sample and test the moisture content at 20-30℃. When the moisture content is ≤800ppm, add the dehydrating agent and vacuum stir for 20-40 minutes; then cool to room temperature and vacuum stir for 1-2 hours before discharging.

[0040] (2) Preparation of component B:

[0041] B1: Add polyurethane-modified epoxy resin, plasticizer, and filler to the reaction vessel, and stir under vacuum at 20-30℃ for 0.5-2 hours;

[0042] B2: Add catalyst and water, stir under vacuum at 20-30℃ for 20-40 minutes, and then discharge.

[0043] When using dual-tube packaging, simply insert the tube into the application gun and dispense a small amount of adhesive, ensuring even and free flow on both sides. If automatic mixing of components A and B is required, connect the mixing nozzle to the automatic mixer and begin dispensing components A and B. For manual mixing, dispense the required amount of components A and B and mix thoroughly for 15 seconds.

[0044] When using bulk containers, mix components A and B thoroughly by weight for approximately 15 seconds.

[0045] When used for bonding substrates, the following steps are included:

[0046] Apply the encapsulating adhesive evenly to the surface of one substrate or two substrates to be joined; the application should be completed within the applicable time of 40-60 minutes, with the two substrates in contact with each other; prevent movement during the curing process, apply contact pressure if necessary, and complete curing at room temperature.

[0047] For high-strength structural components, remove surface contaminants from the substrate, such as paint, oxide film, oil, dust, release agents, and all other surface contaminants.

[0048] The beneficial effects of this invention are as follows:

[0049] The encapsulation adhesive provided by this invention has excellent temperature resistance, good colloid flexibility, low modulus at low temperatures, and excellent aging performance. After mixing and curing components A and B, it forms a cured body with excellent sealing performance, good airtightness, and good adaptability to substrates. It can be used for PACK frame sealing in power batteries, bonding between cells, bonding between cells and heat dissipation components, and bonding and fixing between cells and modules. It is an encapsulation material that provides long-term and comprehensive protection for power batteries. Moreover, components A and B are free of volatiles and have low odor, which is beneficial to the use environment and operators. Detailed Implementation

[0050] The principles and features of the present invention are described below with reference to embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0051] Homemade trimethoxysilane-terminated polyether:

[0052] By weight, PTMG2000 was added to a three-necked flask at room temperature, then the temperature was raised to 40°C and stirred at 40°C for 10 minutes. The reactants were observed to be homogeneous and free of lumps. The temperature of the heating mantle was then adjusted to raise the material temperature to 115°C while simultaneously drawing a vacuum to -0.1 MPa. After stirring for 2 hours, the temperature was lowered to 60°C and 3-isocyanate-propyltrimethoxysilane, a silane coupling agent containing NCO, was added. The temperature was then raised to 80°C and stirred under vacuum for 2 hours before the reaction was stopped and the material was discharged. The molar ratio of PTMG2000 to the silane coupling agent 3-isocyanate-propyltrimethoxysilane was 1:2.

[0053] Pretreatment of packing material:

[0054] Place 1.5% of the total mass of nano-calcium carbonate powder, silane coupling agent KH570, into the storage tank of the spraying equipment. Then, heat the nano-calcium carbonate powder with a particle size of 10-15μm (D50 range) to 80℃, turn on the spraying equipment, and spray the atomized silane coupling agent KH570 while stirring. After spraying is completed, place it in a 110℃ oven to dry for 16 hours for later use.

[0055] Example 1:

[0056] An encapsulating adhesive comprises the following components in parts by weight:

[0057] Component A: 80 parts of trimethoxysilane-terminated polyether (self-made), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.5 parts of dehydrating agent vinyltrimethoxysilane, and 22 parts of filler (pretreatment).

[0058] Component B: 65 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 27 parts of plasticizer polypropylene glycol 2000, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 23 parts of filler (pretreatment).

[0059] The preparation method of the encapsulating adhesive includes the following steps:

[0060] (1) Preparation of component A

[0061] A1: Add trimethoxysilane-terminated polyether, epoxy curing agent, filler, and coupling agent to the reaction vessel, and stir for 2 hours at 25°C, vacuum degree -0.1MPa, and stirring speed of 600rpm.

[0062] A2: Continue to maintain the temperature at 25℃, take samples to test the moisture content, and when the moisture content is ≤800ppm, add the dehydrating agent, vacuum to -0.1MPa, stir at 600rpm for 30min; then cool to room temperature, vacuum at -0.1MPa, stir at 600rpm for 1.5h, and then discharge and pack into a pipe.

[0063] (2) Preparation of component B:

[0064] B1: Add polyurethane modified epoxy resin, filler, and plasticizer to the reaction vessel, evacuate to -0.1MPa at 25℃, stir at 600rpm for 1h;

[0065] B2: Add catalyst and water, continue to apply vacuum (0.1 MPa, 25°C), stir at 600 rpm for 30 minutes, then discharge and pack into a pipe.

[0066] Post-processing: Using a centrifuge, centrifuge the double-tube packaged adhesive at 800 rpm for 5 minutes at room temperature to remove air bubbles, and store the finished product at room temperature.

[0067] Example 2:

[0068] An encapsulating adhesive comprises the following components in parts by weight:

[0069] Component A: 78 parts of trimethoxysilane-terminated polyether (self-made), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.5 parts of dehydrating agent vinyltrimethoxysilane, and 24 parts of filler (pretreatment).

[0070] Component B: 64 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 28 parts of plasticizer polypropylene glycol 2000, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 23 parts of filler (pretreatment).

[0071] The preparation of the encapsulating adhesive is the same as in Example 1, and will not be repeated here.

[0072] Example 3:

[0073] An encapsulating adhesive comprises the following components in parts by weight:

[0074] Component A: 76 parts of trimethoxysilane-terminated polyether (self-made), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.2 parts of dehydrating agent vinyltrimethoxysilane, and 26 parts of filler (pretreatment).

[0075] Component B: 63 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 29 parts of plasticizer polypropylene glycol 2000, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 23 parts of filler (pretreatment).

[0076] The preparation of the encapsulating adhesive is the same as in Example 1, and will not be repeated here.

[0077] Example 4:

[0078] An encapsulating adhesive comprises the following components in parts by weight:

[0079] Component A: 74 parts of trimethoxysilane-terminated polyether (self-made), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.5 parts of dehydrating agent vinyltrimethoxysilane, and 28 parts of filler (pretreatment).

[0080] Component B: 62 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 30 parts of plasticizer polypropylene glycol 2000, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 23 parts of filler (pretreatment);

[0081] The preparation of the encapsulating adhesive is the same as in Example 1, and will not be repeated here.

[0082] Comparative Example 1:

[0083] An encapsulating adhesive comprises the following components in parts by weight:

[0084] Component A: 90 parts of trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500), 8 parts of epoxy curing agent polyetheramine D230, 1.5 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 0 parts of dehydrating agent vinyltrimethoxysilane, and 23 parts of filler (pretreatment).

[0085] Component B: 92 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 2000 parts of plasticizer polypropylene glycol, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 23 parts of filler (pretreatment);

[0086] The preparation of the encapsulating adhesive differs from that in Example 1 in that "trimethoxysilane-terminated polyether (self-made)" is replaced with "trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500)". Everything else is the same and will not be repeated here.

[0087] Comparative Example 2:

[0088] An encapsulating adhesive comprises the following components in parts by weight:

[0089] Component A: 88 parts of trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.5 parts of dehydrating agent vinyltrimethoxysilane, and 14 parts of filler (pretreatment).

[0090] Component B: 65 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 2000 parts of plasticizer polypropylene glycol, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 25 parts of filler (pretreatment).

[0091] The preparation of the encapsulating adhesive differs from that in Example 1 in that "trimethoxysilane-terminated polyether (self-made)" is replaced with "trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500)". Everything else is the same and will not be repeated here.

[0092] Comparative Example 3

[0093] An encapsulating adhesive comprises the following components in parts by weight:

[0094] Component A: 80 parts of trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.5 parts of dehydrating agent vinyltrimethoxysilane, and 22 parts of filler (pretreatment).

[0095] Component B: 65 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 27 parts of plasticizer polypropylene glycol 2000, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 23 parts of filler (pretreatment).

[0096] The preparation of the encapsulating adhesive differs from that in Example 1 in that "trimethoxysilane-terminated polyether (self-made)" is replaced with "trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500)". Everything else is the same and will not be repeated here.

[0097] Comparative Example 4

[0098] An encapsulating adhesive comprises the following components in parts by weight:

[0099] Component A: 84 parts of trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500), 8 parts of epoxy curing agent polyetheramine D230, 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane, 1.5 parts of dehydrating agent vinyltrimethoxysilane, and 16 parts of filler (pretreatment).

[0100] Component B: 65 parts of polyurethane modified epoxy resin (Hunan Servi Materials Co., Ltd. ENC-3801), 28 parts of plasticizer polypropylene glycol 2000, 1.2 parts of catalyst chelated tin, 1.5 parts of deionized water, and 25 parts of filler (pretreatment).

[0101] The preparation of the encapsulating adhesive differs from that in Example 1 in that "trimethoxysilane-terminated polyether (self-made)" is replaced with "trimethoxy-modified silane-terminated polyether (Shandong Lingxiao New Material Co., Ltd., 3500)". Everything else is the same and will not be repeated here.

[0102] Detection:

[0103] According to the usage instructions for the encapsulating adhesive, connect the mixing nozzle to the automatic mixer, and perform testing using the dispensing and application of adhesive with the mixing glue gun:

[0104] Working time: The time from when a multi-component adhesive is prepared until it maintains its performance. Under standard conditions, the time it takes for a 2g application of the mixed adhesive into a tart cup, followed by a toothpick application, to result in an irreversible scratch.

[0105] Hardness: The ability of a material to resist indentation by a hard object on its surface is called hardness. Preparation of fully cured test specimens: The thickness should be at least 6 mm, which can be achieved by stacking three 2 mm specimens or two 3 mm specimens; the area should be at least 100 mm * 100 mm, and the test point should be at least 15 mm from the edge; the surface near the test point should be flat and parallel vertically. Following the hardness tester operating instructions, the test sample should be cured at room temperature for 7 days. Surface hardness testing at room temperature: the maximum indentation speed is 3.2 mm / s, held for 3 seconds, and data should be taken from at least five different locations, averaging the results.

[0106] Modulus: (ASTM E1640-13 Standard Test Method for Assignment of the Glass Transition Temperature By Dynamic Mechanical Analysis), sample size (thickness × width × length) between 1×5×20mm and 1×10×50mm; temperature range -40℃ to 85℃, heating rate 1℃ / min, tensile clamps used, test frequencies including 33Hz and 1Hz, amplitude 0.1 parts of clamping length.

[0107] Pull-out strength: also known as pull-out force test, is a method for evaluating the strength or endurance of a material or product during tensile or pull-out processes. (GB / T 6329 Determination of tensile strength of adhesive butt joints) The specimen joint consists of two square or round rod-shaped adhesives joined together, with the adhesive surface perpendicular to the longitudinal axis of the specimen. The tensile force is transmitted through the longitudinal axis of the specimen to the adhesive surface until the specimen fails. The load at which the specimen fails is taken as the test result.

[0108] The test bar material should be 6061 aluminum. Unless otherwise specified, the dimensions of the test bars should conform to the following: round test bars should have a diameter of 10mm, 15mm, 25mm, or 50mm; square test bars should have a side length of 10mm, 15mm, 25mm, or 50mm. The tolerance range for the above dimensions is ±0.1mm. For test bars with a diameter or side length of 10mm or 15mm, the length should be three times the diameter or side length; for test bars with a diameter or side length of 25mm or 50mm, the length should be 50mm. The adhesive bonding surface of the test bar should be flat and perpendicular to the longitudinal axis of the test bar. The other end of the test bar opposite the adhesive bonding surface should have a pin hole for connection to the clamp of the tensile testing machine. Sufficient adhesive should be used for the adhesive joint, leaving a slight excess adhesive around the joint to avoid under-adhesive joints. Excess adhesive usually does not need to be removed; if it must be removed, it must be done before hardening. After hardening, the specimen should be tested under no-pressure conditions. Unless otherwise specified, the number of samples should not be less than 5, and the test conditions are recommended to be carried out at 23±2℃ and equivalent humidity of 50±5%. For Al-PET-Al sandwich pull-out samples, both sides should be 0.2mm thick, with the copper wire or rubber strip thickness limited; the tensile rate is 5mm / min.

[0109] Shear strength: A longitudinal tensile shear force is applied to the lap joint of the specimen, and the maximum load that the specimen can withstand is determined. Under standard conditions, polished carbon steel is uniformly glued, overlapped, and fixed. After 24 hours, the testing machine is started, and a load is applied at a stable speed of 10 mm / min. The maximum load at which the specimen fails in shear is recorded, and the length and width of the lap joint are measured using measuring tools to calculate the tensile shear strength.

[0110] Tensile strength and elongation at break: Tensile strength is the maximum stress a material can withstand during tension. Elongation at break is the ratio of the maximum deformation before fracture to the original length during tension. Prepare a 2mm thick adhesive-cured sample, ensuring a smooth, flat, and contamination-free surface. After the sample is fully cured, allow it to stand in a laboratory environment for 3 hours, then cut standard strips using a type I dumbbell cutter. At least three strips should be cut.

[0111] Thermal shock: To test the ability to withstand thermal shock conditions, a thermal shock testing machine was used. The equipment was continuously exposed at -40°C for 30 minutes, then rapidly switched to 85°C for another 30 minutes. This cycle was repeated 100 times.

[0112] Humidity and heat aging: According to GB / T 2423.3 Environmental Testing Part 2: Test Methods, Test Cab: Constant Humidity and Heat Test, the sample was placed in a constant temperature and humidity chamber at 85±3℃ and 82-88 parts RH for 1000 hours, then removed and placed at room temperature for another 2 hours. Performance testing was then conducted according to the standard test method.

[0113] The test results are shown in Table 1:

[0114] Table 1 Test Results

[0115]

[0116] As can be seen from the data in Table 1, the encapsulating adhesives of Examples 1 to 4 have a bulk strength and shear strength ≥10MPa, elongation at break >180%, modulus >300MPa after curing, and the modulus is still very low at -40℃. They are environmentally friendly low-temperature flexible adhesives that do not contain NCO and have a low shear strength decay rate after thermal shock and damp heat aging, with a strength retention rate >90%. In contrast, the shear strength, pull-out strength, bulk strength, elongation at break, and modulus of Comparative Examples 1 to 4 are all lower than those of the Examples, and the shear strength decay rate after aging is higher than that of the Examples.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An encapsulating adhesive, characterized in that, The preparation process includes: (1) Preparation of trimethoxysilane-terminated polyether: At room temperature, polytetrahydrofuran diol PTMG2000 was added to a three-necked flask, and then the temperature was raised to 40°C. The mixture was stirred at 40°C for 10 min. The reactants were observed to be homogeneous and free of lumps. The temperature of the heating mantle was then adjusted to raise the material temperature to 115°C and simultaneously vacuumed to -0.1 MPa. After stirring for 2 h, the temperature was lowered to 60°C and 3-isocyanate-propyltrimethoxysilane, a silane coupling agent containing NCO, was added. The temperature was then raised to 80°C and the reaction was stopped after vacuum stirring for 2 h. The molar ratio of PTMG2000 to 3-isocyanate-propyltrimethoxysilane was 1:

2. (2) Filler preparation: Place 1.5% of the total mass of nano-calcium carbonate powder, silane coupling agent KH570, into the storage tank of the spraying equipment. Then heat the nano-calcium carbonate powder with a particle size of 10-15μm and a total particle size of 97-99.5% to 80℃, turn on the spraying equipment, spray the atomized silane coupling agent KH570, and stir while spraying. After spraying is completed, place it in a 110℃ oven to dry for 16 hours for later use. (3) Preparation of component A: By weight, 80 parts of trimethoxysilane-terminated polyether prepared in step (1), 8 parts of epoxy curing agent polyetheramine D230, 22 parts of filler prepared in step (2), and 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane were added to the reaction vessel. The mixture was stirred for 2 hours at 25°C, vacuum degree -0.1MPa, and stirring speed of 600rpm. The temperature was maintained at 25°C, and the water content was tested. When the water content was ≤800ppm, 1.5 parts of dehydrating agent vinyltrimethoxysilane were added, the vacuum was reduced to -0.1MPa, and the stirring speed was 600rpm for 30 minutes. Then the mixture was cooled to room temperature, vacuumed to -0.1MPa, and stirred for 1.5 hours at 600rpm. The mixture was then discharged and loaded into a tube. (4) Preparation of component B: By weight, 65 parts of polyurethane modified epoxy resin ENC-3801 from Hunan Servi Materials Co., Ltd., 23 parts of filler prepared in step (2), and 27 parts of plasticizer polypropylene glycol 2000 were added to the reaction vessel. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 1 h. 1.2 parts of chelated tin catalyst and 1.5 parts of deionized water were added. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 30 min. The mixture was then discharged and loaded into a tube.

2. An encapsulating adhesive, characterized in that, The preparation process includes: (1) Preparation of trimethoxysilane-terminated polyether: At room temperature, polytetrahydrofuran diol PTMG2000 was added to a three-necked flask, and then the temperature was raised to 40°C. The mixture was stirred at 40°C for 10 min. The reactants were observed to be homogeneous and free of lumps. The temperature of the heating mantle was then adjusted to raise the material temperature to 115°C and simultaneously vacuumed to -0.1 MPa. After stirring for 2 h, the temperature was lowered to 60°C and 3-isocyanate-propyltrimethoxysilane, a silane coupling agent containing NCO, was added. The temperature was then raised to 80°C and the reaction was stopped after vacuum stirring for 2 h. The molar ratio of PTMG2000 to 3-isocyanate-propyltrimethoxysilane was 1:

2. (2) Filler preparation: Place 1.5% of the total mass of nano-calcium carbonate powder, silane coupling agent KH570, into the storage tank of the spraying equipment. Then heat the nano-calcium carbonate powder with a particle size of 10-15μm and a total particle size of 97-99.5% to 80℃, turn on the spraying equipment, spray the atomized silane coupling agent KH570, and stir while spraying. After spraying is completed, place it in a 110℃ oven to dry for 16 hours for later use. (3) Preparation of component A: By weight, 78 parts of trimethoxysilane-terminated polyether prepared in step (1), 8 parts of epoxy curing agent polyetheramine D230, 24 parts of filler prepared in step (2), and 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane were added to the reaction vessel. The mixture was stirred for 2 hours at 25°C, vacuum degree -0.1MPa, and stirring speed of 600rpm. The temperature was maintained at 25°C, and the water content was tested. When the water content was ≤800ppm, 1.5 parts of dehydrating agent vinyltrimethoxysilane were added, vacuum was drawn to -0.1MPa, and stirring speed was 600rpm for 30 minutes. Then the mixture was cooled to room temperature, vacuumed to -0.1MPa, and stirred at 600rpm for 1.5 hours. The mixture was then discharged and loaded into a tube. (4) Preparation of component B: By weight, 4 parts of polyurethane modified epoxy resin ENC-38016 from Hunan Servi Materials Co., Ltd., 23 parts of filler prepared in step (2), and 28 parts of plasticizer polypropylene glycol 2000 were added to the reaction vessel. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 1 h. 1.2 parts of chelated tin catalyst and 1.5 parts of deionized water were added. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 30 min. The mixture was then discharged and loaded into a tube.

3. An encapsulating adhesive, characterized in that, The preparation process includes: (1) Preparation of trimethoxysilane-terminated polyether: At room temperature, polytetrahydrofuran diol PTMG2000 was added to a three-necked flask, and then the temperature was raised to 40°C. The mixture was stirred at 40°C for 10 min. The reactants were observed to be homogeneous and free of lumps. The temperature of the heating mantle was then adjusted to raise the material temperature to 115°C and simultaneously vacuumed to -0.1 MPa. After stirring for 2 h, the temperature was lowered to 60°C and 3-isocyanate-propyltrimethoxysilane, a silane coupling agent containing NCO, was added. The temperature was then raised to 80°C and the reaction was stopped after vacuum stirring for 2 h. The molar ratio of PTMG2000 to 3-isocyanate-propyltrimethoxysilane was 1:

2. (2) Filler preparation: Place 1.5% of the total mass of nano-calcium carbonate powder, silane coupling agent KH570, into the storage tank of the spraying equipment. Then heat the nano-calcium carbonate powder with a particle size of 10-15μm and a total particle size of 97-99.5% to 80℃, turn on the spraying equipment, spray the atomized silane coupling agent KH570, and stir while spraying. After spraying is completed, place it in a 110℃ oven to dry for 16 hours for later use. (3) Preparation of component A: By weight, 76 parts of trimethoxysilane-terminated polyether prepared in step (1), 8 parts of epoxy curing agent polyetheramine D230, 26 parts of filler prepared in step (2), and 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane were added to the reaction vessel. The mixture was stirred for 2 hours at 25°C, vacuum degree -0.1MPa, and stirring speed of 600rpm. The temperature was maintained at 25°C, and the water content was tested. When the water content was ≤800ppm, 1.2 parts of dehydrating agent vinyltrimethoxysilane were added, the vacuum was reduced to -0.1MPa, and the stirring speed was 600rpm for 30 minutes. Then the mixture was cooled to room temperature, vacuumed to -0.1MPa, and stirred for 1.5 hours at 600rpm. The mixture was then discharged and loaded into a tube. (4) Preparation of component B: By weight, 3 parts of polyurethane modified epoxy resin ENC-38016 from Hunan Servi Materials Co., Ltd., 23 parts of filler prepared in step (2), and 29 parts of plasticizer polypropylene glycol 2000 were added to the reaction vessel. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 1 h. 1.2 parts of chelated tin catalyst and 1.5 parts of deionized water were added. The vessel was evacuated again to -0.1 MPa at 25°C and stirred at 600 rpm for 30 min. The mixture was then discharged and loaded into a tube.

4. An encapsulating adhesive, characterized in that, The preparation process includes: (1) Preparation of trimethoxysilane-terminated polyether: At room temperature, polytetrahydrofuran diol PTMG2000 was added to a three-necked flask, and then the temperature was raised to 40°C. The mixture was stirred at 40°C for 10 min. The reactants were observed to be homogeneous and free of lumps. The temperature of the heating mantle was then adjusted to raise the material temperature to 115°C and simultaneously vacuumed to -0.1 MPa. After stirring for 2 h, the temperature was lowered to 60°C and 3-isocyanate-propyltrimethoxysilane, a silane coupling agent containing NCO, was added. The temperature was then raised to 80°C and the reaction was stopped after vacuum stirring for 2 h. The molar ratio of PTMG2000 to 3-isocyanate-propyltrimethoxysilane was 1:

2. (2) Filler preparation: Place 1.5% of the total mass of nano-calcium carbonate powder, silane coupling agent KH570, into the storage tank of the spraying equipment. Then heat the nano-calcium carbonate powder with a particle size of 10-15μm and a total particle size of 97-99.5% to 80℃, turn on the spraying equipment, spray the atomized silane coupling agent KH570, and stir while spraying. After spraying is completed, place it in a 110℃ oven to dry for 16 hours for later use. (3) Preparation of component A: By weight, 74 parts of trimethoxysilane-terminated polyether prepared in step (1), 8 parts of epoxy curing agent polyetheramine D230, 28 parts of filler prepared in step (2), and 1.2 parts of coupling agent γ-methacryloyloxypropyltrimethoxysilane were added to the reaction vessel. The mixture was stirred for 2 hours at 25°C, vacuum degree -0.1MPa, and stirring speed of 600rpm. The temperature was maintained at 25°C, and the water content was tested. When the water content was ≤800ppm, 1.5 parts of dehydrating agent vinyltrimethoxysilane were added, the vacuum was reduced to -0.1MPa, and the stirring speed was 600rpm for 30 minutes. Then the mixture was cooled to room temperature, vacuumed to -0.1MPa, and stirred for 1.5 hours at 600rpm. The mixture was then discharged and loaded into a tube. (4) Preparation of component B: By weight, 2 parts of polyurethane modified epoxy resin ENC-38016 from Hunan Servi Materials Co., Ltd., 23 parts of filler prepared in step (2), and 30 parts of plasticizer polypropylene glycol 2000 were added to the reaction vessel. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 1 h. 1.2 parts of chelated tin catalyst and 1.5 parts of deionized water were added. The vessel was evacuated to -0.1 MPa at 25°C and stirred at 600 rpm for 30 min. The mixture was then discharged and loaded into a tube.

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