Epoxy adhesive as well as preparation method and application thereof

Abstract

The invention discloses an epoxy adhesive as well as a preparation method and application thereof, and belongs to the technical field of adhesives. The epoxy adhesive provided by the invention comprises modified epoxy resin and microcapsules, the modified epoxy resin is a reaction product of acrylate resin and epoxy resin; monomers of the acrylate resin comprise acrylate and hydroxyl acrylate; the hydroxyl acrylate accounts for 0.1 to 0.5 mol percent of the monomer; the microcapsule comprises a capsule wall and a content contained in the capsule wall; the content comprises an amine curing agent and a photo-thermal material, and the amine curing agent comprises at least one of polyamide tertiary amine, fatty amine polyamine and aromatic polyamine. The epoxy adhesive provided by the invention has relatively high initial viscosity, toughness after curing, storage stability and curing speed. The invention also provides a preparation method and application of the epoxy adhesive.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and in particular to an epoxy adhesive, its preparation method, and its application. Background Technology

[0002] Epoxy resin adhesives are widely used in numerous industrial fields such as electronic component packaging, aerospace, automotive manufacturing, and construction engineering due to their excellent bonding strength, outstanding chemical resistance, good heat resistance, and low shrinkage. However, traditional epoxy resin adhesive systems still have some long-standing technical defects that have not been properly resolved, severely limiting their application in a wider range of scenarios, especially in situations requiring high efficiency and ease of operation.

[0003] First, poor initial tack (initial adhesion) is a significant drawback of epoxy adhesives. Most two-component epoxy adhesives have low initial viscosity after mixing, lacking sufficient thixotropy or initial tack, causing the bonded parts to easily shift or slip during the early stages of curing. This necessitates the use of additional clamps or fixing devices, greatly reducing construction efficiency and making it difficult to meet the needs of automated production lines. Second, epoxy resins have high crosslinking density after curing, resulting in insufficient bulk toughness and high brittleness. This leads to poor impact resistance, peel resistance, and fatigue resistance, making the bond interface prone to cracking failure under dynamic loads or thermal stress impacts. Although toughening agents such as liquid rubber, thermoplastics, or nanoparticles can improve toughness, these methods often lead to a significant increase in system viscosity, a decrease in modulus and heat resistance, and even the introduction of new compatibility problems. Third, two-component adhesives are cumbersome to use, while single-component adhesives present an irreconcilable contradiction between storage stability and curing speed. One-component epoxy adhesives typically use latent curing agents, which, while exhibiting excellent storage stability, usually require high temperatures (e.g., above 120°C) to activate the curing agent. This is not only energy-intensive but also unsuitable for substrates with poor heat resistance (such as certain plastics and electronic components), limiting their application range. Furthermore, some existing latent curing technologies, such as microencapsulated curing agents, while stable at room temperature, often suffer from low capsule wall rupture efficiency, incomplete curing agent release, and the need for external pressure or specific triggering conditions. These issues lead to slow or incomplete curing reactions, preventing rapid curing and affecting the reliability of the final bond performance.

[0004] Therefore, there is an urgent need in this field to develop a new type of epoxy adhesive to solve the above problems. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an epoxy adhesive that can effectively improve its initial tack, cured toughness, storage stability, and curing speed.

[0006] The present invention also provides a method for preparing the above-mentioned epoxy adhesive.

[0007] The present invention also provides an epoxy tape comprising the above-described epoxy adhesive.

[0008] According to an embodiment of a first aspect of the present invention, an epoxy adhesive is provided, the epoxy adhesive comprising a modified epoxy resin and microcapsules; The modified epoxy resin is a reaction product of acrylate resin and epoxy resin; the monomers of the acrylate resin include acrylate and hydroxy acrylate; the molar percentage of the hydroxy acrylate in the monomers is 0.1~0.5%; The microcapsule includes a capsule wall and contents contained within the capsule wall; the contents include an amine curing agent and a photothermal material, wherein the amine curing agent includes at least one of polyamide tertiary amine, fatty amine polyamine and aromatic polyamine.

[0009] The epoxy adhesive according to embodiments of the present invention has at least the following beneficial effects: In the epoxy adhesive provided by this invention, acrylate resin is introduced into the modified epoxy resin and its monomer types are limited. The resulting acrylate resin is linear, essentially unbranched, and has a low degree of crosslinking. Therefore, it can stretch in the epoxy adhesive, increasing its toughness. At the same time, the acrylate resin itself has a certain degree of adhesion and is an important component of self-adhesive adhesives. Therefore, it can also provide a certain initial tack to the epoxy adhesive.

[0010] In the reaction process of acrylate resin and epoxy resin, the hydroxyl groups in hydroxyacrylate act as a connecting bridge between the two resins. This invention limits the content of hydroxyacrylate, so there are fewer connection sites between the acrylate resin and epoxy resin, and the molecular chain of the acrylate resin is not completely fixed. Therefore, there are enough gaps for the amine curing agent released by the microcapsule to penetrate, and thus the curing speed is not significantly reduced.

[0011] The microcapsules provided by this invention incorporate photothermal materials, thus allowing external light to be used to promote the release of the amine curing agent in actual production. Additionally, a light source can be added to initiate the curing of the acrylate resin, further promoting its curing and providing intermediate-stage adhesion before the epoxy resin cures.

[0012] In the epoxy adhesive provided by the present invention, photothermal materials are gathered inside microcapsules; and the photothermal materials are locally enriched and stacked to form microstructures. When light shines on its surface, multiple reflections can occur in it, improving photothermal efficiency. Therefore, local high temperature can be formed, promoting the rupture of the capsule wall and releasing amine curing agents.

[0013] According to some embodiments of the present invention, the mass ratio of the acrylate resin to the epoxy resin is 5 to 10:100. For example, it can be 5:100, 6:100, 7:100, 8:100, 9:100, 10:100; or a range of values ​​consisting of any two of the above points.

[0014] According to some embodiments of the present invention, the hydroxyacrylate accounts for 0.1 to 0.5% of the molar percentage of the monomer. For example, it may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%; or a range of values ​​consisting of any two of the above points.

[0015] According to some embodiments of the present invention, the hydroxyacrylate includes at least one of methyl hydroxyacrylate and ethyl hydroxyacrylate.

[0016] According to some embodiments of the present invention, the acrylate includes at least one of methyl acrylate and ethyl acrylate.

[0017] Generally speaking, the monomers are selected to minimize the presence of branches, thereby increasing the degree of freedom of the acrylate resin molecular chains and improving their extensibility.

[0018] According to some embodiments of the present invention, the capsule wall ruptures in the range of 40~70°C.

[0019] According to some embodiments of the present invention, the material of the capsule wall includes at least one of polylactic acid and polycaprolactone.

[0020] According to some embodiments of the present invention, the photothermal material includes a carbon-based material.

[0021] According to some embodiments of the present invention, the photothermal material includes at least two of carbon nanotubes, graphene, and carbon black. This allows the construction of porous stacked systems using carbon-based materials with different microstructures, increasing light reflection and refraction, improving light utilization efficiency, and ultimately increasing the heating rate under illumination conditions, thus promoting the rapid curing of modified epoxy resins.

[0022] When the photothermal material includes carbon nanotubes and graphene, the mass ratio of the two is 1:0.8 to 1.2. For example, it can be 1:0.8, 1:1, 1:1.2; or a range of values ​​consisting of any two of the above points.

[0023] According to some embodiments of the present invention, the mass ratio of the amine curing agent, the photothermal material, and the capsule wall in the microcapsule is 1~3:1:2~5. Specifically, it can be 1:1:2, 1:1:3, 1:1:4, 1:1:5, 2:1:2, 2:1:3, 2:1:4, 2:1:5, 3:1:2, 3:1:3, 3:1:4, 3:1:5; or a range of values ​​consisting of any two of the above points.

[0024] According to some embodiments of the present invention, the amount of the amine curing agent added is 110-160% of the theoretically required amount of the epoxy resin. For example, it can be 110%, 120%, 130%, 140%, 150%, 160%; or a range of values ​​composed of any two of the above points.

[0025] According to some embodiments of the present invention, the epoxy adhesive further includes additives. The amount and type of the additives are not strictly limited in the present invention; in actual production, suitable additives can be selected based on experience and experimental conditions.

[0026] By way of example, the additives include diluents, toughening agents, and thixotropic agents. Among them, the diluents include C12-14 alkyl glycidyl ethers (AGEs).

[0027] More specifically, the mass ratio of the diluent to the modified epoxy resin is 0.05~0.15:1.

[0028] The mass ratio of the toughening agent to the modified epoxy resin is 0.05~0.15:1.

[0029] The mass ratio of the thixotropic agent to the modified ion resin is 0.02~0.06:1.

[0030] According to an embodiment of a second aspect of the present invention, a method for preparing the epoxy adhesive described in the first aspect of the present invention is provided, the method comprising mixing the components of the epoxy adhesive.

[0031] Since the preparation method adopts all the technical solutions of the epoxy adhesive in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0032] According to some embodiments of the present invention, the synthesis of the acrylate resin includes the following steps: A1. In an inert atmosphere, a portion of acrylate, solvent, chain transfer agent, and a portion of initiator are mixed and reacted; A2. Add the remaining acrylate and the remaining initiator dropwise to the mixture obtained in step A1 to continue the reaction; A3. The hydroxyacrylate is added dropwise to the mixture obtained in step A2 to continue the reaction.

[0033] According to some embodiments of the present invention, the initiator accounts for 0.1 to 0.5% of the monomer mass. For example, it may specifically be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%; or a range of values ​​consisting of any two of the above points.

[0034] According to some embodiments of the present invention, the chain transfer agent accounts for 0.1 to 1.0% of the monomer mass. For example, it may specifically be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%; or a range of values ​​consisting of any two of the above points.

[0035] According to some embodiments of the present invention, in step A1, the acrylate accounts for 40-60% of the total acrylate molar percentage. For example, it can be 50%.

[0036] According to some embodiments of the present invention, in step A1, the solvent includes at least one of ethyl acetate and alcohol solvents.

[0037] According to some embodiments of the present invention, in step A1, the chain transfer agent includes at least one of dodecyl mercaptan, mercaptoethanol, and mercaptoacetic acid.

[0038] According to some embodiments of the present invention, in step A1, the initiator accounts for 40-60% of the total molar percentage of all initiators. For example, it can be 50%.

[0039] According to some embodiments of the present invention, in step A1, the initiator includes at least one of a peroxide initiator and an azo initiator.

[0040] According to some embodiments of the present invention, in step A1, the mixing reaction includes a reflux reaction.

[0041] According to some embodiments of the present invention, in step A1, the duration of the mixing reaction is 20-50 minutes. For example, it can be 30 minutes.

[0042] According to some embodiments of the present invention, in step A2, the temperature for the continued reaction is 100~150°C. For example, it can be 120°C.

[0043] According to some embodiments of the present invention, in step A2, the duration of the continued reaction is 50 to 100 minutes. For example, it can be 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, or 100 minutes; or a range of values ​​composed of any two of the above points.

[0044] According to some embodiments of the present invention, in step A2, the dripping time is 30-60 minutes. For example, it can be 30 minutes, 40 minutes, 50 minutes, 60 minutes; or a range of values ​​composed of any two of the above points.

[0045] According to some embodiments of the present invention, in step A3, the duration of the continued reaction is 10-30 minutes. Furthermore, the other conditions for step A3 are the same as those for step A2.

[0046] According to some embodiments of the present invention, the method for synthesizing the acrylate resin further includes a purification step performed after step A3.

[0047] According to some embodiments of the present invention, the method for synthesizing the modified epoxy resin includes mixing and reacting the acrylate resin and the epoxy resin in a system containing a catalyst and a solvent. Wherein, The catalyst used includes tetramethylammonium chloride; the catalyst accounts for 0.3-0.8% of the mass of the epoxy resin. For example, it can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%; or a range of any two of the above values.

[0048] The solvent used includes ethylene glycol ethyl ether acetate; the mass ratio of the solvent to the epoxy resin is 1:0.8~1.2.

[0049] The mixed reaction includes a first-stage reaction and a second-stage reaction that proceed sequentially.

[0050] The temperature for the first stage reaction is 80~100℃; The duration of the first stage reaction is 1 to 2 hours.

[0051] The temperature for the second stage reaction is 100~110℃.

[0052] The second stage of the reaction lasts 8 to 12 hours.

[0053] According to some embodiments of the present invention, the method for preparing the microcapsules includes the following steps: B1. Prepare an aqueous phase containing a water-soluble surfactant; An oil phase is prepared, wherein the oil phase contains the curing agent, the capsule wall precursor, the photothermal material, and an oil-soluble surfactant.

[0054] Prepare a stabilizer solution containing PVA; B2. Mix the oil phase and the aqueous phase and pour the mixture into the stabilizer solution and stir until the solvent in the oil phase has completely evaporated.

[0055] According to some embodiments of the present invention, in step B1, the water-soluble surfactant includes Tween 80.

[0056] According to some embodiments of the present invention, in step B1, the concentration of the water-soluble surfactant is 8~10 mg / mL.

[0057] According to some embodiments of the present invention, in step B1, the oily surfactant includes Span 20.

[0058] According to some embodiments of the present invention, in step B1, the mass ratio of the oily surfactant to the amine curing agent is 1~2:10.

[0059] According to some embodiments of the present invention, in step B1, the solvent of the oil phase includes DCM (dichloromethane).

[0060] According to some embodiments of the present invention, in step B1, the concentration of the amine curing agent in the oil phase is 0.1~0.3 mg / mL.

[0061] According to some embodiments of the present invention, in step B1, the mass concentration of the stabilizer solution is 0.5~1.5%.

[0062] According to some embodiments of the present invention, in step B1, the stabilizer includes polyvinyl alcohol.

[0063] According to some embodiments of the present invention, in step B2, the volume ratio of the oil phase, the aqueous phase and the stabilizer solution is 1:3~5:5~8.

[0064] According to an embodiment of a third aspect of the present invention, an epoxy tape is provided, the epoxy tape comprising a substrate and an adhesive layer disposed on the surface of the substrate, wherein the raw material of the adhesive layer comprises the epoxy adhesive described in the first aspect of the present invention, or the epoxy adhesive prepared by the preparation method described in the second aspect of the present invention.

[0065] Since the epoxy tape adopts all the technical solutions of the epoxy adhesive in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0066] According to some embodiments of the present invention, the method for preparing the epoxy tape includes coating the epoxy adhesive onto the surface of a substrate and then removing the solvent.

[0067] The substrate needs to have high transparency and low adhesion to the epoxy adhesive; for example, it can be PET or PI.

[0068] The epoxy adhesive provided by this invention can be used directly or prepared into epoxy tape. During use, two types of light are required: ultraviolet light and sunlight. The application time for ultraviolet light is between 30 and 90 seconds; the application time for sunlight needs to be ≥10 minutes to encourage the photothermal conversion material to convert the light into heat, thereby promoting the rupture of the capsule wall and the curing of the double bonds in the acrylate resin segments and the epoxy groups in the epoxy resin segments of the modified epoxy resin.

[0069] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0070] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0071] Example 1 This example demonstrates the preparation of an epoxy adhesive, with the specific steps as follows: S1. Material Preparation Synthetic acrylate resins: A1. In an inert nitrogen atmosphere, half a volume of methyl acrylate, ethyl acetate solvent, dodecyl mercaptan chain transfer agent, and half a volume of azobisisobutyronitrile initiator are mixed and reacted; the reaction is carried out at reflux temperature for 30 min. A2. Add the remaining methyl acrylate and the remaining initiator azobisisobutyronitrile dropwise to the mixture obtained in step A1 and continue the reaction; the dropwise addition time is 1 hour; the reaction temperature is 120°C and the reaction time is 70 minutes. A3. Add methyl hydroxyacrylate dropwise to the mixture obtained in step A2 and continue the reaction; the reaction time is 20 minutes. Since the amount of methyl hydroxyacrylate used is very small, the actual dropwise addition time is also very short, and this example does not strictly limit it; if the reaction volume is increased, the dropwise addition time should be controlled between 20 and 30 minutes.

[0072] A4. Vacuum distillation removes unreacted raw materials and solvents.

[0073] In the synthesis of acrylate resin, the solvent is twice the mass of the monomer (methyl acrylate + methyl hydroxyacrylate); the chain transfer agent is 0.3% of the monomer mass; the initiator accounts for 0.2% of the monomer mass; and the methyl hydroxyacrylate accounts for 0.3% of the monomer molar percentage.

[0074] Synthetic modified epoxy resin: The acrylate resin, epoxy resin (bisphenol A epoxy resin 816: bisphenol F epoxy resin 862 = 1:1 mass ratio), catalyst, and solvent obtained in step A4 are mixed and reacted, and then the solvent is removed under reduced pressure; wherein... The mass ratio of acrylate resin to epoxy resin is 8:100; The catalyst is tetramethylammonium chloride, and it accounts for 0.5% of the epoxy resin by mass. The solvent is ethylene glycol ethyl ether acetate, and the mass ratio of it to epoxy resin is 1:1; The temperature mechanism for the mixed reaction is as follows: first react at 90℃ for 1.5h, then react at 105℃ for 10h.

[0075] Synthetic microcapsules: B1. Preparation of aqueous phase: Prepare an aqueous solution of Tween 80 at a mass ratio of 9 mg / mL.

[0076] Preparation of the oil phase: The solvent for the oil phase is DCM (dichloromethane), and the solutes are fatty amines, polycaprolactone, and Span 20, and it also includes solid dispersions of photothermal materials; among which, The ratio of fatty amine MH-6610 (Changsha Xindehang Chemical Co., Ltd.) to solvent is 0.2 g / mL; The ratio of polycaprolactone (molecular weight approximately 15,000, melting point in the range of 59~64℃) to solvent is 0.3 g / mL; The ratio of Span 20 to solvent is 0.03 g / mL; The photothermal material is a mixture of oligowalled carbon nanotubes (purchased from Xianfeng Nano, No. XFD04) and graphene (purchased from Xianfeng Nano, No. XF269) in a 1:1 mass ratio; the ratio of photothermal material to solvent is 0.1 g / mL.

[0077] Prepare a stabilizer solution, which is an aqueous solution of 1% PVA (number average molecular weight of 4000).

[0078] B2. Pour the oil phase into the aqueous phase and emulsify by high-speed mechanical stirring at 1000 rpm for 30 minutes; The resulting mixture was poured into the stabilizer solution and reacted at a low mechanical stirring speed of 300 rpm at 40°C for about 4 hours. If the DCM was not completely evaporated, the temperature was maintained and the mixture was distilled under reduced pressure to promote its complete evaporation.

[0079] The volume ratio of the oil phase, aqueous phase, and stabilizer solution is 1:4:5.

[0080] S2. Mixing The modified epoxy resin, diluent (AGE), toughening agent (ppg-2000), thixotropic agent (HL-200) and microcapsules are mixed evenly to obtain the product.

[0081] The mass ratio of modified epoxy resin, diluent, toughening agent, and thixotropic agent is 10:1:1:0.5. The fatty amine added to the microcapsules is 110% of the amount of curing agent theoretically required for the modified epoxy resin.

[0082] Example 2 This example prepares an epoxy adhesive, which differs from Example 1 in that: The photothermal material is oligowalled carbon nanotubes, and the source and total amount of the photothermal material are the same as in Example 1.

[0083] Example 3 This example prepares an epoxy adhesive, which differs from Example 1 in that: In the preparation of acrylate resin, methyl hydroxyacrylate accounts for 0.5% of the molar percentage of the monomer.

[0084] Comparative Example 1 This example prepares an epoxy adhesive, which differs from Example 1 in that: In the microcapsule preparation process, no photothermal material is added. Instead, an equal amount of photothermal material is added to the mixing step in step S2.

[0085] Comparative Example 2 This example prepares an epoxy adhesive, which differs from Example 1 in that: In the preparation of acrylate resins, hydroxyacrylates account for 0.7% of the monomer mass percentage.

[0086] Comparative Example 3 This example prepares an epoxy adhesive, which differs from Example 1 in that: Excluding the synthesis step of the modified resin, in step S2, equal amounts of acrylate resin, epoxy resin and other components from Example 1 are directly mixed.

[0087] Application examples This example demonstrates the preparation of an epoxy tape, specifically obtained by coating the epoxy adhesive obtained in the examples or comparative examples onto a substrate and removing the solvent by vacuum evaporation. Drying temperature ≤ 40℃; The film thickness after drying is 0.1 mm.

[0088] The matrix is ​​PET.

[0089] Test case This example tests the performance of the epoxy tape obtained in the application example. Specifically, the epoxy tape was applied to the surface of an oil-free, rust-free, and dry steel plate (1.5mm thick, flexible enough to bend within a certain angle range), and then simultaneously subjected to sunlight and a 200W UV lamp. After 1 minute of irradiation, the UV light source was removed, and curing continued for 6 hours. The following tests were conducted during the process: Before applying light, place the adhesive surface perpendicular to the horizontal plane for 10 minutes and observe the displacement distance of the adhesive position.

[0090] After removing the UV lamp, test the adhesion and record it as intermediate adhesion.

[0091] After curing, test the adhesion and record it as the final adhesion.

[0092] Bend the steel plate to 175° and bend it back and forth 10 times to see if the adhesive layer breaks.

[0093] The above adhesion test method refers to GB / T 2792 The procedure was carried out in 2014, with a peeling length of 25 mm.

[0094] The test results are shown in Table 1.

[0095] Table 1. Performance of the epoxy adhesives obtained in the examples and comparative examples

[0096] The analysis of the test results in Table 1 is as follows: Within the scope of this invention, although there may be fluctuations in performance, the resulting epoxy adhesive generally exhibits fast curing speed, simple curing conditions, good toughness, and excellent initial adhesion, intermediate adhesion, and final adhesion.

[0097] Comparing Examples 1 and 2, it can be seen that when graphene and carbon nanotubes are used as hybrid photothermal materials, they can have a synergistic effect, which can improve the refraction and reflection of light inside the photothermal material to a certain extent, improve the utilization rate of light, improve the heating effect per unit time, and promote the curing effect of temperature on acrylate resin and epoxy resin.

[0098] Comparing Examples 1, 3, and 2, it is evident that increasing the amount of hydroxyl acrylate increases the number of bonding sites between the acrylate resin and the epoxy resin, effectively increasing the crosslinking density. Before the epoxy resin fully contacts the curing agent, a higher crosslinking density inhibits the curing agent's penetration and slows down the curing speed. Furthermore, the increased crosslinking density significantly increases the brittleness of the cured epoxy adhesive. Therefore, compared to Example 1, the effects of Examples 3 and 2 are significantly reduced. Simultaneously, with excessively high crosslinking density, the molecular chains of the acrylate resin cannot effectively extend and contact the matrix material, thus negatively impacting the initial tack.

[0099] Comparing the results of Example 1 and Comparative Example 1, it can be seen that the photothermal material dispersed throughout the matrix has poor aggregation, the matrix consumes a lot of light, and therefore the proportion of light used for heating is small. As a result, the temperature during the curing process cannot be effectively increased, and the capsule wall cannot be broken. Therefore, the epoxy resin cannot be cured, or the curing speed is very slow. When the light is removed, the epoxy adhesive has not been fully cured, so the adhesion strength is very low. In addition, the photothermal material cannot provide initial tack and may hinder the contact between the acrylic resin and the matrix to a certain extent, thus reducing the initial viscosity.

[0100] Comparing the results of Example 1 and Comparative Example 3, it can be seen that if there is no connection between the acrylate resin and the epoxy resin, the phases of the resulting epoxy adhesive will not be well integrated, and cracking and displacement will easily occur inside the adhesive, thus deteriorating the overall performance.

[0101] In summary, the epoxy adhesive provided by this invention possesses excellent initial viscosity, intermediate viscosity, and final adhesion strength, along with superior toughness and simple curing; it can be used alone or formulated into epoxy tapes. Due to these advantages, the epoxy adhesive provided by this invention is expected to find wide application in the fields of construction, machinery, and microelectronics.

[0102] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An epoxy adhesive, characterized in that, The epoxy adhesive comprises modified epoxy resin and microcapsules; The modified epoxy resin is a reaction product of acrylate resin and epoxy resin; the monomers of the acrylate resin include acrylate and hydroxy acrylate; the molar percentage of the hydroxy acrylate in the monomers is 0.1~0.5%; The microcapsule includes a capsule wall and contents contained within the capsule wall; the contents include an amine curing agent and a photothermal material, wherein the amine curing agent includes at least one of polyamide tertiary amine, fatty amine polyamine and aromatic polyamine.

2. The epoxy adhesive according to claim 1, characterized in that, The capsule wall ruptures within the range of 40~70℃.

3. The epoxy adhesive according to claim 1, characterized in that, The photothermal material includes carbon-based materials.

4. The epoxy adhesive according to claim 1, characterized in that, The amount of the amine curing agent added is 100-150% of the theoretical amount required for the epoxy resin.

5. The epoxy adhesive according to claim 1, characterized in that, The mass ratio of the acrylate resin to the epoxy resin is 5~10:

100.

6. A method for preparing the epoxy adhesive as described in any one of claims 1 to 5, characterized in that, The preparation method includes mixing the components of the epoxy adhesive.

7. The preparation method according to claim 6, characterized in that, The synthesis of the acrylate resin includes the following steps: A1. In an inert atmosphere, a portion of acrylate, solvent, chain transfer agent, and a portion of initiator are mixed and reacted; A2. Add the remaining acrylate and the remaining initiator dropwise to the mixture obtained in step A1 to continue the reaction; A3. The hydroxyacrylate is added dropwise to the mixture obtained in step A2 to continue the reaction.

8. The preparation method according to claim 7, characterized in that, The initiator accounts for 0.1 to 0.5% of the monomer mass; and / or, the chain transfer agent accounts for 0.1 to 1.0% of the monomer mass.

9. The preparation method according to claim 6, characterized in that, The method for preparing the microcapsules includes the following steps: B1. Prepare an aqueous phase containing a water-soluble surfactant; Prepare an oil phase containing the curing agent, the capsule wall precursor, the photothermal material, and an oil-soluble surfactant; Prepare a stabilizer solution containing PVA; B2. Mix the oil phase and the aqueous phase and pour the mixture into the stabilizer solution and stir until the solvent in the oil phase has completely evaporated.

10. An epoxy tape, characterized in that, The epoxy tape includes a substrate and an adhesive layer disposed on the surface of the substrate. The raw material of the adhesive layer includes the epoxy adhesive as described in any one of claims 1 to 5, or the epoxy adhesive prepared by the preparation method as described in any one of claims 6 to 8.

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