Epoxy adhesive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of sealing, and relates to an epoxy adhesive as well as a preparation method and application thereof. The epoxy adhesive contains an epoxy resin-polyether amine prepolymer, a polyether amine curing agent and optional filler, coupling agent, curing accelerator and assistant, the epoxy resin-polyether amine prepolymer comprises at least one section of epoxy resin chain segment and at least one section of polyether amine chain segment, and both ends of the epoxy resin-polyether amine prepolymer are terminated by epoxy groups; the glass transition temperature Tg of the cured epoxy adhesive is below-20 DEG C; the key of the invention lies in that a polyether amine chain segment is introduced into the epoxy resin, polyether amine is selected as a curing agent, and the glass transition temperature Tg of the cured epoxy adhesive is controlled to be-20 DEG C or below, so that the obtained epoxy adhesive not only has excellent oil resistance and high pressure resistance, but also has good high and low temperature impact resistance; the failure phenomena of degumming, cracking and the like are not easy to occur after multiple times of hot and cold impact, and the strict reliability requirement of the electric automobile industry can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of sealing and relates to an epoxy adhesive and a preparation method and application thereof. Background Art

[0002] Traditional automotive electrical sealing technologies, such as those used to seal wiring harnesses and terminal blocks, generally use rubber sealing rings with bolt locking. This sealing method is simple to construct and highly reliable, but it is unable to seal special-shaped parts. With the iterative upgrades of electrical equipment, workpiece designs are becoming increasingly complex, and special-shaped structures are becoming more and more common. Therefore, traditional sealing technologies are gradually being replaced by adhesive sealing technologies. With the booming development of new energy vehicles in recent years, the technical indicators of electrical sealing have been increasing year by year, especially for pure electric vehicles on the 800V high-voltage platform. These requirements for electrical sealing include resistance to high voltage, high and low temperatures, oil resistance, and water resistance. At the same time, the sealant is also required to have good fluidity and fast curing to take into account assembly efficiency.

[0003] Currently, mainstream automotive electrical insulation sealants primarily use epoxy resin as the main resin. Epoxy resin has a low cure shrinkage rate and forms a high-density, three-dimensional cross-linked network structure after curing, resulting in good high-temperature tolerance. However, it has disadvantages such as resin hardening and cracking at low temperatures. Due to thermal expansion and contraction, epoxy cured products are prone to failure such as debonding and cracking after repeated thermal shocks. Therefore, there is an urgent need to modify epoxy adhesives to improve the resin cracking problem at low temperatures and make them more resilient after repeated thermal shocks. Summary of the Invention

[0004] The first object of the present invention is to provide an epoxy adhesive that has good high and low temperature impact resistance, is oil resistant and high pressure resistant, and is not prone to debonding and cracking after being cured and subjected to multiple hot and cold shocks.

[0005] A second object of the present invention is to provide a method for preparing the epoxy adhesive.

[0006] The third object of the present invention is to provide application of the above-mentioned epoxy adhesive in the field of consumer electronics.

[0007] The epoxy adhesive provided by the present invention contains an epoxy resin-polyetheramine prepolymer and a polyetheramine curing agent, as well as optional fillers, coupling agents, curing accelerators and auxiliary agents. The epoxy resin-polyetheramine prepolymer includes at least one epoxy resin segment and at least one polyetheramine segment, and both ends of the epoxy resin-polyetheramine prepolymer are end-capped with epoxy groups. The epoxy adhesive has a glass transition temperature Tg of below -20°C after curing.

[0008] The key to the present invention lies in introducing polyetheramine segments into epoxy resin and selecting polyetheramine as a curing agent. At the same time, the glass transition temperature (Tg) of the epoxy adhesive after curing is controlled to be below -20°C. The resulting epoxy adhesive not only has excellent oil resistance and high-pressure resistance, but also has good high- and low-temperature impact resistance. It is not prone to failure phenomena such as debonding and cracking after multiple hot and cold shocks, and can meet the stringent reliability requirements of the electric vehicle industry. DETAILED DESCRIPTION

[0009] The epoxy adhesive provided by the present invention contains an epoxy resin-polyetheramine prepolymer and a polyetheramine curing agent, and optionally a filler, a coupling agent, a accelerator, and an auxiliary agent. The mass ratio of the polyetheramine curing agent to the epoxy resin-polyetheramine prepolymer is preferably (15-400):100, such as 15:100, 20:100, 50:100, 80:100, 100:100, 120:100, 150:100, 180:100, 200:100, 220:100, 250:100, 280:100, 300:100, 320:100, 350:100, 380:100, 400:100, or any value therebetween. The mass ratio of the filler to the epoxy resin-polyetheramine prepolymer is (0-1000):100, such as 0, 20:100, 50:100, 80:100, 100:100, 200:100, 300:100, 400:100, 500:100, 600:100, 700:100, 800:100, 900:100, 1000:100 or any value therebetween. The mass ratio of the coupling agent to the epoxy resin-polyetheramine prepolymer is (0-20):100, such as 0, 0.1:100, 0.5:100, 1:100, 2:100, 4:100, 6:100, 8:100, 10:100, 12:100, 14:100, 16:100, 18:100, 20:100 or any value therebetween. The mass ratio of the accelerator to the epoxy resin-polyetheramine prepolymer is (0-20):100, such as 0, 0.1:100, 0.5:100, 1:100, 2:100, 4:100, 6:100, 8:100, 10:100, 12:100, 14:100, 16:100, 18:100, 20:100 or any value therebetween. The mass ratio of the auxiliary agent to the epoxy resin-polyetheramine prepolymer is (0-100):100, such as 0, 0.1:100, 0.5:100, 1:100, 2:100, 5:100, 10:100, 20:100, 30:100, 40:100, 50:100, 60:100, 70:100, 80:100, 90:100, 100:100 or any value therebetween.

[0010] In a preferred embodiment, the content of the epoxy resin-polyetheramine prepolymer is 5 to 30 parts by weight, such as 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30 parts by weight or any value therebetween; the content of the polyetheramine curing agent is 5 to 20 parts by weight, such as 5, 8, 10, 12, 15, 18, 20 parts by weight or any value therebetween; the content of the filler is 20 to 50 parts by weight, such as 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50 parts by weight or any value therebetween; the content of the coupling agent is 0.1 to 1 part by weight, such as 0.1, 0.2, 0.4, 0.6, 0.8, 1 part by weight or any value therebetween; the content of the accelerator is 0.1 to 1 part by weight, such as 0.1, 0.2, 0.4, 0.6, 0.8, 1 part by weight or any value therebetween; the content of the auxiliary agent is 0.1 to 5 parts by weight, such as 0.1, 0.5, 1, 2, 3, 4, 5 parts by weight or any value therebetween.

[0011] In the present invention, the glass transition temperature (Tg) of the epoxy adhesive after curing is below -20°C, specifically -20°C, -22°C, -25°C, -28°C, -30°C, -32°C, -35°C, -38°C, -40°C, -45°C, -50°C, etc. The glass transition temperature (Tg) of the epoxy adhesive is related to the composition of the segments in the epoxy resin-polyetheramine prepolymer and the specific type of curing agent. The epoxy resin-polyetheramine prepolymer includes at least one epoxy resin segment and at least one polyetheramine segment, and both ends of the epoxy resin-polyetheramine prepolymer are end-capped with epoxy groups. The epoxy resin-polyetheramine prepolymer can be purchased commercially or prepared according to various existing methods. In a preferred embodiment, the epoxy resin-polyetheramine prepolymer is obtained by an addition reaction between an epoxy resin and a polyetheramine end-capped with primary amines. The feed ratio of the epoxy resin to the polyetheramine is preferably such that the ratio of the total moles of epoxy to the total moles of active hydrogen in the starting system is (2.5-5):1, specifically 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any value therebetween. The epoxy equivalent weight of the epoxy resin is preferably 150-500 g / mol, such as 150, 200, 250, 300, 350, 400, 450, 500 g / mol, or any value therebetween. The active hydrogen equivalent weight of the polyetheramine is preferably 100-1250 g / mol, such as 100, 200, 300, 400, 600, 800, 1000, 1250 g / mol, or any value therebetween. The conditions of the addition reaction preferably include a temperature of 150-180°C, such as 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C or any value therebetween; and a time of 60-180 min, such as 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min or any value therebetween.

[0012] In the present invention, the epoxy resin used in the preparation of the epoxy resin-polyetheramine prepolymer can be an aliphatic epoxy resin having two or more epoxy groups, an aromatic epoxy resin having two or more epoxy groups, or a mixture of the two. The aliphatic epoxy resin can be at least one of a binary epoxy resin and a ternary epoxy resin. Specific examples of the binary epoxy resin include, but are not limited to, at least one of (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, polytetramethylene ether glycol diglycidyl ether, glycerol diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexane diglycidyl ether, and dicyclopentadiene diglycidyl ether. Specific examples of the ternary epoxy resin include, but are not limited to, trimethylolpropane triglycidyl ether and / or glycerol triglycidyl ether. As the cyclohexane-type diglycidyl ether, cyclohexanedimethanol diglycidyl ether is particularly preferred. The aromatic epoxy resin can be any of the various existing epoxy resins having two epoxy groups and containing an aromatic ring structure, specific examples of which include but are not limited to: bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, novolac epoxy resin, tetrabromobisphenol A epoxy resin, fluorene epoxy resin, biphenyl aralkyl epoxy resin, diepoxy resin (such as 1,4-phenyl dimethanol diglycidyl ether), biphenyl epoxy resin (such as 3,3',5,5'-tetramethyl-4,4'-diglycidyloxybiphenyl), glycidylamine epoxy resin (such as diglycidyl aniline, diglycidyl toluidine, triglycidyl para-aminophenol, tetraglycidyl meta-xylene diamine, etc.), and at least one of naphthalene ring-containing epoxy resins, preferably at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and glycidylamine epoxy resin. Particularly preferably, the epoxy resin is bisphenol A epoxy resin and / or bisphenol F epoxy resin, which have the advantages of moderate reactivity, strong adhesion, and easy availability of raw materials.

[0013] The present invention does not specifically limit the type of polyetheramine used in the preparation process of the epoxy resin-polyetheramine prepolymer. It can be any existing polymer having a polyether backbone and an amino active end, preferably having a structure represented by formula (1). When the polyetheramine has the structure represented by formula (1), it has better oil resistance, low temperature resistance, and impact resistance. This is because the polyetheramine chain segment not only has high flexibility, but also has medium polarity and a denser molecular arrangement. This enables it to maintain good performance under low temperature and impact, and also gives it stronger anti-penetration ability to non-polar oils.

[0014]

[0015] In formula (1), n ​​is a positive integer from 1 to 50, and specifically can be 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or any value therebetween.

[0016] The polyetheramine curing agent of the present invention preferably has a structure as shown in formula (1). The reason is that the polyetheramine of this structure has the characteristics of good oil resistance, low temperature resistance, and impact resistance. In addition, the high-density three-dimensional cross-linked network structure formed after the epoxy resin is cured will cause the glass transition temperature of the cured product to be too high, making it too hard at low temperatures. In addition, after repeated hot and cold shocks, it is easy to cause failure phenomena such as degumming and cracking. Using a polyetheramine with the above specific structure as a curing agent can effectively reduce the glass transition temperature of the cured product and enhance the reliability of the cured product in extreme environments (such as high and low temperature shocks and hot oil immersion). In addition, the polyetheramine curing agent has a low reaction temperature and can not only continue to cure at room temperature or even at low temperature to ensure sufficient curing, but also has a mild curing reaction, low heat release, and small shrinkage after curing, making it particularly suitable for large-scale potting.

[0017] In the present invention, the filler is added to reduce the expansion coefficient and the curing shrinkage. The filler can be at least one of silicon dioxide, aluminum oxide, magnesium oxide, zinc oxide, aluminum hydroxide, boron nitride, silicon carbide, talc, calcium carbonate, glass microspheres, graphite powder, and metal powder.

[0018] In the present invention, the role of the coupling agent is to improve the dispersion performance of inorganic substances in the adhesive system, and to improve the bonding performance between the adhesive and the inorganic substrate, thereby increasing the bonding strength. The coupling agent can be selected from at least one of aminosilane, epoxysilane, thiosilane, methacryloxysilane, vinylsilane, ureasilane and isocyanatesilane. Specific examples include but are not limited to: at least one of γ-methacryloxypropyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, anilinemethyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-ureapropyltriethoxysilane.

[0019] In the present invention, the type of the curing accelerator is not particularly limited and can be any of various existing substances capable of accelerating the curing rate of epoxy resins, for example, amine accelerators, imidazole accelerators, etc. The amine accelerator can specifically be an amine-epoxy adduct (a reaction product of an amine compound and an epoxy compound), a urea adduct (a reaction product of an amine compound and an isocyanate compound or a urea compound), etc. Examples of the amine-epoxy adducts include AMICURE PN-23 (Ajinomoto Fine-Techno Co., Ltd.), AMICURE PN-40 (Ajinomoto Fine-Techno Co., Ltd.), AMICURE PN-50 (Ajinomoto Fine-Techno Co., Ltd.), Hardener X-361S (ACR Co., Ltd.), Hardener X-3670S (ACR Co., Ltd.), NOVACURE HX-3742 (Asahi Kasei Corporation), OVACURE HX-3721 (Asahi Kasei Corporation), NOVACURE HXA9322HP (Asahi Kasei Corporation), NOVACURE HXA3922HP (Asahi Kasei Corporation), NOVACURE HXA3932HP (Asahi Kasei Corporation), NOVACURE HXA5945HP (Asahi Kasei Corporation), NOVACURE HXA9382HP (Asahi Kasei Corporation), and Fujicure fXr1121 (T&K Toka Corporation). Examples of the urea-type adducts include Fujicure FXe-1000 (T&K TOKA Co., Ltd.) and Fujicure FXr-1030 (T&K TOKA Co., Ltd.). Examples of the imidazole accelerators include 1-benzyl-2-methylimidazole, 1-benzyl-2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1-aminoethyl-2-methylimidazole.

[0020] In the present invention, the auxiliary agent can be selectively added according to actual conditions, and the auxiliary agent can be exemplified by at least one of a colorant, a leveling agent, a defoaming agent, and an antioxidant. The types and addition amounts of the above auxiliary agents can be conventionally selected in the art and are not described in detail here.

[0021] The preparation method of the epoxy adhesive provided by the present invention comprises uniformly mixing an epoxy resin-polyetheramine prepolymer and a polyetheramine curing agent, and optionally a filler, a coupling agent, an accelerator, and an auxiliary agent. The order in which the components are mixed is not particularly limited, and the materials can be added and mixed in any order. Preferably, the liquid material is first added to a double planetary stirred tank, stirring is started to thoroughly mix the materials, and then the powder material is added and stirred until the materials are thoroughly mixed. The mixture is then optionally ground to obtain the epoxy adhesive.

[0022] The present invention also provides application of the epoxy adhesive in the field of consumer electronics.

[0023] The present invention will be described in detail below by way of examples. The examples of the examples are intended to explain the present invention and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the examples, the methods were performed according to the techniques or conditions described in the literature in the art or according to the product specifications. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be obtained commercially.

[0024] In the following examples and comparative examples, the amounts of each component are in parts by weight.

[0025] In the following examples and comparative examples, bisphenol A epoxy resin was purchased from Mitsubishi Chemical Corporation with a brand name of 828 and an epoxy equivalent weight of 188 g / mol; bisphenol F epoxy resin was purchased from Mitsubishi Chemical Corporation with a brand name of 806 and an epoxy equivalent weight of 165 g / mol.

[0026] Preparation Example 1

[0027] Bisphenol A epoxy resin and polyetheramine (having a structure shown in formula (1) and a number average molecular weight of 5000) were stirred and mixed uniformly. The feed ratio of bisphenol A epoxy resin to polyetheramine was such that the ratio of the total molar number of epoxy to the total molar number of active hydrogen in the starting system was 2.5:1. The resulting solution was heated to 150° C. and stirred for reaction for 180 minutes. After the reaction was completed, the product was divided into iron containers while hot and cooled to obtain an epoxy resin-polyetheramine prepolymer, which was recorded as EP-PEA-1.

[0028] Preparation Example 2

[0029] Bisphenol F epoxy resin and polyetheramine (having a structure shown in formula (1) and a number average molecular weight of 2000) were stirred and mixed uniformly. The feed ratio of bisphenol F epoxy resin to polyetheramine was such that the ratio of the total molar number of epoxy to the total molar number of active hydrogen in the starting system was 5:1. The resulting solution was heated to 180° C. and stirred for reaction for 60 minutes. After the reaction was completed, the product was divided into iron containers while hot and cooled to obtain an epoxy resin-polyetheramine prepolymer, which was recorded as EP-PEA-2.

[0030] Preparation Example 3

[0031] Bisphenol A epoxy resin and polyetheramine (having a structure shown in formula (1) and a number average molecular weight of 230) were stirred and mixed uniformly. The feed ratio of bisphenol A epoxy resin to polyetheramine was such that the ratio of the total molar number of epoxy to the total molar number of active hydrogen in the starting system was 3:1. The resulting solution was heated to 160° C. and stirred for reaction for 180 minutes. After the reaction was completed, the product was dispensed into iron containers while hot and cooled to obtain an epoxy resin-polyetheramine prepolymer, which was recorded as EP-PEA-3.

[0032] Preparation Example 4

[0033] An epoxy resin-polyetheramine prepolymer was prepared according to the method of Example 1, except that the polyetheramine was replaced by a non-preferred polyetheramine (having a structure represented by formula (2) and a number average molecular weight of 4980) having the same molar number of active hydrogen. The remaining conditions were the same as in Example 1 to obtain an epoxy resin-polyetheramine prepolymer, which was designated as EP-PEA-4.

[0034]

[0035] Comparative Preparation Example 1

[0036] A prepolymer was prepared according to the method of Example 1, except that the polyetheramine was replaced by ethylenediamine with the same total molar number of active hydrogen. Other conditions were the same as in Example 1 to obtain a reference epoxy resin-amine prepolymer, which was recorded as DEP-PEA-1.

[0037] Comparative Preparation Example 2

[0038] A prepolymer was prepared according to the method of Example 1, except that the polyetheramine was replaced by p-phenylenediamine with the same total molar number of active hydrogen. Other conditions were the same as in Example 1 to obtain a reference epoxy resin-amine prepolymer, which was recorded as DEP-PEA-2.

[0039] Example 1

[0040] 5 parts of epoxy resin-polyetheramine prepolymer (EP-PEA-1), 5 parts of polyetheramine curing agent, 0.1 parts of γ-methacryloxypropyltrimethoxysilane, and 0.1 parts of 1-benzyl-2-methylimidazole were put into a double planetary stirring kettle, and stirring was started to fully mix the materials. Then 20 parts of silica and 0.5 parts of carbon black were added, and stirring was continued until all the materials were fully mixed to obtain an epoxy resin adhesive.

[0041] Example 2

[0042] 30 parts of epoxy resin-polyetheramine prepolymer (EP-PEA-2), 20 parts of polyetheramine curing agent, 1 part of vinyl tris(β-methoxyethoxy) silane, and 1 part of 2-ethyl-4-methylimidazole were put into a double planetary stirring kettle, and stirring was started to fully mix the materials. Then 50 parts of silica and 0.5 parts of carbon black were added, and stirring was continued until all the materials were fully mixed to obtain an epoxy resin adhesive.

[0043] Example 3

[0044] 15 parts of epoxy resin-polyetheramine prepolymer (EP-PEA-3), 10 parts of polyetheramine curing agent, 0.5 parts of γ-aminopropyltrimethoxysilane, and 0.5 parts of 1-benzyl-2-methylimidazole were put into a double planetary stirred tank, and stirring was started to fully mix the materials. Then 35 parts of silica and 0.1 parts of carbon black were added, and stirring was continued until all the materials were fully mixed to obtain an epoxy adhesive.

[0045] Example 4

[0046] An epoxy adhesive was prepared according to the method of Example 1, except that the epoxy resin-polyetheramine prepolymer (EP-PEA-1) was replaced by the epoxy resin-amine prepolymer (EP-PEA-4) in equal parts by weight. The remaining conditions were the same as in Example 1 to obtain an epoxy adhesive.

[0047] Comparative Example 1

[0048] An epoxy adhesive was prepared according to the method of Example 1, except that the epoxy resin-polyetheramine prepolymer (EP-PEA-1) was replaced by the epoxy resin-amine prepolymer (DEP-PEA-1) in equal parts by weight. The remaining conditions were the same as in Example 1 to obtain an epoxy adhesive.

[0049] Comparative Example 2

[0050] An epoxy adhesive was prepared according to the method of Example 1, except that the epoxy resin-polyetheramine prepolymer (EP-PEA-1) was replaced by the epoxy resin-amine prepolymer (DEP-PEA-2) in equal parts by weight. The remaining conditions were the same as in Example 1 to obtain an epoxy adhesive.

[0051] Test Case

[0052] (1) Glass transition temperature (Tg): The epoxy adhesives obtained in the above examples and comparative examples were injected into a specific mold and cured at room temperature for 72 hours to form cylindrical specimens with a diameter of 6 mm and a height of 5 mm. The glass transition temperature (Tg) of the specimens was measured using a TA TMA450. The lower the Tg, the better the low-temperature resistance of the surface epoxy adhesive. The results are shown in Table 1.

[0053] (2) Oil resistance: The epoxy adhesives obtained in the above embodiments and comparative examples were injected into a specific mold and cured at room temperature for 72 hours to finally form a thin sheet with a thickness of 1 mm. The thin sheet was cut into dumbbell films, and the elongation at break was tested using an Instron universal testing machine. The remaining dumbbell films were then immersed in 150°C engine oil for aging for 1000 hours, and the elongation at break was repeated after being taken out. For the use scenario of this product, an elongation at break of ≥50% is required to maintain good sealing. Comparing the data changes before and after hot oil immersion, the less the elongation at break decreases and the final elongation at break is still ≥50%, the better the oil resistance. The results are shown in Table 1.

[0054] (3) High-Voltage Resistance: The epoxy adhesives obtained in the above Examples and Comparative Examples were injected into a specific mold and cured at room temperature for 72 hours to form a 1 mm thick sheet. The sheet was cut into circular specimens with a diameter of 60 mm and the volume resistivity was measured using a Keithley high resistance meter (DC 1 kV). The higher the volume resistivity, the better the high-voltage resistance. The results are shown in Table 1.

[0055] (4) Resistance to high and low temperature impact: After the carbon steel sheets were sandblasted, they were overlapped and bonded in pairs using the epoxy adhesive obtained from the above embodiments and comparative examples to prepare standard shear specimens. The overlap area was 25.4×12.5 mm. After curing at room temperature for 72 hours, the shear strength was tested using an Instron universal testing machine. The remaining shear specimens were then placed in a hot and cold shock tester and subjected to 1,000 hot and cold shock tests within a temperature range of -50 to 150°C, followed by another shear strength test. Comparing the data changes before and after the hot and cold shocks, the smaller the reduction, the better the resistance to high and low temperature impact. The results are shown in Table 1.

[0056]

Claims

1. An epoxy adhesive, characterized in that: The epoxy adhesive contains an epoxy resin-polyetheramine prepolymer and a polyetheramine curing agent, as well as optional fillers, coupling agents, curing accelerators and additives. The epoxy resin-polyetheramine prepolymer includes at least one epoxy resin segment and at least one polyetheramine segment, and both ends of the epoxy resin-polyetheramine prepolymer are end-capped with epoxy groups. The glass transition temperature Tg of the epoxy adhesive after curing is below -20°C.

2. The epoxy adhesive according to claim 1, characterized in that The content of the epoxy resin-polyetheramine prepolymer is 5 to 30 parts by weight, the content of the polyetheramine curing agent is 5 to 20 parts by weight, the content of the filler is 20 to 50 parts by weight, the content of the coupling agent is 0.1 to 1 part by weight, the content of the curing accelerator is 0.1 to 1 part by weight, and the content of the auxiliary agent is 0.1 to 5 parts by weight.

3. The epoxy adhesive according to claim 1, wherein The epoxy resin-polyetheramine prepolymer is obtained by performing an addition reaction between epoxy resin and primary amine-terminated polyetheramine.

4. The epoxy adhesive according to claim 4, characterized in that The epoxy equivalent of the epoxy resin is 150 to 500 g / mol; and the active hydrogen equivalent of the polyetheramine is 50 to 1500 g / mol.

5. The epoxy adhesive according to claim 4, characterized in that The epoxy resin is bisphenol A epoxy resin and / or bisphenol F epoxy resin.

6. The epoxy adhesive according to claim 4, characterized in that The polyetheramine has a structure shown in formula (1): In formula (1), n ​​is a positive integer of 1 to 50.

7. The epoxy adhesive according to claim 1, wherein The conditions of the addition reaction include a temperature of 150 to 180° C. and a time of 60 to 180 minutes.

8. The epoxy adhesive according to claim 1, wherein The polyetheramine curing agent is a polyetheramine with a number average molecular weight of 200 to 5000; The filler is selected from at least one of silicon dioxide, aluminum oxide, magnesium oxide, zinc oxide, aluminum hydroxide, boron nitride, silicon carbide, talc, calcium carbonate, glass microspheres, graphite powder and metal powder; The coupling agent is selected from at least one of γ-methacryloxypropyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, anilinomethyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-ureapropyltriethoxysilane; The curing accelerator is selected from at least one of imidazole compounds, amine-epoxy adducts and urea-type adducts; The auxiliary agent is selected from at least one of a colorant, a leveling agent, a defoaming agent and an antioxidant.

9. The method for preparing the epoxy adhesive according to any one of claims 1 to 8, characterized in that: The method comprises uniformly mixing epoxy resin-polyetheramine prepolymer, polyetheramine curing agent, optional filler, coupling agent, accelerator and auxiliary agent.

10. Use of the epoxy adhesive according to any one of claims 1 to 8 in the field of consumer electronics.

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