A detachable heat-conducting epoxy resin adhesive based on ester exchange and a preparation method thereof

Abstract

The application discloses a preparation method of a detachable heat-conducting epoxy resin adhesive based on ester exchange, and the method comprises the following steps: firstly, a diluent is added into the epoxy resin to reduce the viscosity of the epoxy resin, and then a heat-conducting filler is added to increase the heat conductivity coefficient, so as to prepare a glue solution; secondly, polyols and anhydrides are mixed at a certain proportion, and are reacted for a period of time to prepare a modified curing agent; finally, the measured glue solution and the modified curing agent are mixed, and a promoter is added, and then the mixture is uniformly stirred to obtain the detachable heat-conducting epoxy resin adhesive. The preparation method of the detachable heat-conducting epoxy resin adhesive based on ester exchange has the advantages of high bonding strength, insulation, heat conduction, and the like, and the adhesive can be detached within 60 seconds after high-temperature treatment and curing, and has application prospects in the fields of electronic components, transducer devices and photovoltaic bonding.

Description

Technical Field

[0001] This invention relates to a method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification, belonging to the technical field of epoxy resin adhesives. Background Technology

[0002] Cured epoxy resin is an important thermosetting material, whose excellent mechanical properties, thermal stability, wettability, and adhesion make it a vital component in many industrial applications. However, the permanent cross-linked network formed after curing cannot be disassembled or reprocessed, leading to incorrect installation or ineffective disassembly, repair, and recycling at the end of its service life, thus causing resource waste and environmental pollution. Therefore, achieving the disassembly and recyclability of epoxy resin has become an important issue in materials science.

[0003] In recent years, glass-like epoxy resin systems based on dynamic covalent bonds have attracted widespread attention. A dynamic covalent bond is a chemical bond capable of undergoing reversible reactions under specific conditions; common dynamic bonds include disulfide bonds and imine bonds. Epoxy resins incorporating dynamic covalent bonds not only enable rapid chemical reactions under specific conditions but also endow the materials with self-healing and recyclability.

[0004] Epoxy resins have inherently low thermal conductivity, and adding high thermal conductivity fillers is a common method to improve their thermal conductivity. Filling with high thermal conductivity fillers can create effective thermal conduction channels within the epoxy resin matrix, significantly improving thermal conductivity. The thermal conductivity of filled epoxy resins is mainly affected by the thermal conductivity of the filler, the filler content, and the way it is composited with the matrix. Due to its simple preparation process and low production cost, filled epoxy resins are widely used in industrial fields.

[0005] This invention proposes a method for creating a removable, thermally conductive epoxy resin adhesive. The core idea is to add pretreated, high-thermal-conductivity fillers to the epoxy system to improve the thermal conductivity of the epoxy resin adhesive. Then, polyhydroxy monomers are introduced into the epoxy-anhydride system. Through the preferential reaction of the primary hydroxyl groups in the polyhydroxy monomers with the anhydride, the ring-opening reaction of the epoxy resin is promoted, thereby forming a large number of β-hydroxy ester bonds in the crosslinked network. These hydroxyl groups not only serve as active sites for dynamic transesterification reactions but also exert an endogenous catalytic effect, ensuring rapid curing and dynamic transesterification reactions under catalyst-free conditions. By adjusting the content of the polyhydroxy monomers, the removability of the material can be effectively controlled while maintaining its excellent mechanical and thermal conductivity properties. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification. Under certain temperature conditions, the strength of the epoxy resin adhesive after curing can be reduced, making it easier to disassemble the bonded material, thereby realizing the effective disassembly and recycling of the material.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification is characterized by the following steps: adding a diluent to epoxy resin, mixing and stirring evenly to reduce the viscosity of the epoxy resin; then adding a silane coupling agent and a surface-pretreated thermally conductive filler to improve the thermal conductivity; mixing and stirring a polyol and anhydride to induce the anhydride to open the ring and generate a carboxylic acid to obtain a modified curing agent; finally, adding the modified curing agent to the diluted epoxy resin adhesive, adding an accelerator, mixing and stirring evenly, coating it onto the adhesive material, and curing at high temperature to achieve bonding.

[0009] The features are as follows: the epoxy resin contains an active diluent, such as polyethylene glycol diglycidyl ether, added in an amount of 10-30 parts; the thermally conductive filler after surface pretreatment with silane coupling agent is ZnO or BN, added in an amount of 0-30 parts; the silane coupling agent is KH-550 or KH-560, added in an amount of 1-5 parts; the polyol is trifunctional or higher; the acid anhydride is phthalic anhydride and 4-methylhexahydrophthalic anhydride; the modified curing agent is added in an amount of 75-80 parts; the accelerator is N′N-dimethylbenzylamine, added in an amount of 1 part; high-temperature curing molding is performed, with curing conditions of curing at 100°C for 2 hours and then curing at 150°C for 2 hours.

[0010] The beneficial effects of this invention are: the adhesive has the advantages of high bonding strength, insulation, and thermal conductivity, and the adhesive can be disassembled within 60 seconds after high-temperature curing. Detailed Implementation

[0011] The present invention will be further described in detail below with reference to embodiments and accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0012] Example 1

[0013] 20 parts of polyethylene glycol diglycidyl ether were added to 100 parts of epoxy resin (E-51), and the mixture was stirred until homogeneous to reduce viscosity. Then, 20 parts of pretreated ZnO (KH-550) were added. 0.4 moles of glycerol were added to 1 mole of 4-methylhexahydrophthalic anhydride, and the mixture was stirred to induce ring-opening of the anhydride to generate a carboxylic acid, thus obtaining a modified curing agent. Finally, 75 parts of the curing agent were added to 100 parts of epoxy resin solution, and 1 part of N'N-dimethylbenzylamine was added. The mixture was stirred until homogeneous to obtain a removable thermally conductive epoxy adhesive. Using an aluminum sheet as the bonding object, the adhesive was first cured at 100℃ for 2 hours, then at 150℃ for 2 hours. The shear strength was measured to be 8.3 MPa, the adhesive could be removable after 35 seconds at 140℃, the thermal conductivity was higher than 0.60 W / m·K, and the surface resistivity was greater than 2*10⁻⁶. 9 Ω.

[0014] Example 2

[0015] Add 20 parts of polyethylene glycol diglycidyl ether to 100 parts of epoxy resin (E-51), mix and stir evenly to reduce viscosity, then add 20 parts of KH-550 pretreated ZnO; add 0.2 moles of glycerol to 1 mole of 4-methylhexahydrophthalic anhydride, stir to induce anhydride ring-opening to generate carboxylic acid, and obtain a modified curing agent; finally, add 75 parts of the curing agent to 100 parts of epoxy resin adhesive, then add 1 part of N'N-dimethylbenzylamine, mix and stir evenly to obtain a removable thermally conductive epoxy adhesive; using aluminum sheet as the bonding object, first cure at 100℃ for 2 hours, then continue curing at 150℃ for 2 hours, the shear strength was measured to be 10.1 MPa, it can be removable in 95 seconds at 140℃, the thermal conductivity is higher than 0.62 W / m·K, and the surface resistivity is greater than 2*10 9 Ω.

[0016] Example 3

[0017] 20 parts of polyethylene glycol diglycidyl ether were added to 100 parts of epoxy resin (E-51), and the mixture was stirred until homogeneous to reduce viscosity. Then, 40 parts of pretreated ZnO (KH-550) were added. 0.4 moles of glycerol were added to 1 mole of 4-methylhexahydrophthalic anhydride, and the mixture was stirred to induce ring-opening of the anhydride to generate a carboxylic acid, thus obtaining a modified curing agent. Finally, 75 parts of the curing agent were added to 100 parts of epoxy resin solution, and 1 part of N′N-dimethylbenzylamine was added. The mixture was stirred until homogeneous to obtain a removable thermally conductive epoxy adhesive. Using an aluminum sheet as the bonding object, the adhesive was first cured at 100℃ for 2 hours, then at 150℃ for 2 hours. The shear strength was measured to be 9.2 MPa, the adhesive could be removable in 46 seconds at 140℃, the thermal conductivity was higher than 0.83 W / m·K, and the surface resistivity was greater than 2*10⁻⁶. 9 Ω.

[0018] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification, characterized in that: Includes the following steps: A diluent is added to the epoxy resin and mixed thoroughly to reduce its viscosity. Then, a silane coupling agent is added for surface pretreatment, followed by a thermally conductive filler to improve thermal conductivity. Polyols and acid anhydrides are mixed and stirred to induce ring-opening of the anhydrides to generate carboxylic acids, thus obtaining a modified curing agent. Finally, the modified curing agent is added to the diluted epoxy resin solution, along with an accelerator, and the mixture is stirred thoroughly. The mixture is then applied to the bonding material and cured at high temperature to achieve adhesion.

2. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: The epoxy resin is added with an active diluent, which is polyethylene glycol diglycidyl ether, and the amount added is 10 to 30 parts.

3. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: After surface pretreatment of the silane coupling agent, the thermally conductive filler is ZnO or BN, and the addition amount is 0 to 30 parts.

4. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: Add silane coupling agent KH-550 or KH-560, in amounts of 1 to 5 parts.

5. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: The polyols are trifunctional or higher; the acid anhydrides are phthalic anhydride and 4-methylhexahydrophthalic anhydride.

6. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: The amount of modified curing agent added is 75-80 parts.

7. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: The accelerator N′N-dimethylbenzylamine was added at a rate of 1 part.

8. The method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification according to claim 1, characterized in that: High-temperature curing molding, the curing conditions are 100℃ for 2 hours, and then the temperature is increased to 150℃ for 2 hours.

9. A method for preparing a detachable thermally conductive epoxy resin adhesive based on transesterification, characterized in that: The adhesive has the advantages of high bonding strength, insulation, thermal conductivity, and the ability to be disassembled within 60 seconds after high-temperature curing.

10. A removable, thermally conductive epoxy resin adhesive based on transesterification, characterized in that: It is prepared by the method for preparing the detachable thermally conductive epoxy resin adhesive according to any one of claims 1 to 9.