A removable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and its preparation method

Abstract

This invention discloses a method for preparing a detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds. The method includes the following steps: First, a diluent is added to the epoxy resin to reduce its viscosity, and a thermally conductive filler is added to increase its thermal conductivity to prepare an adhesive solution. Second, a diphenol with dynamic disulfide bonds and an anhydride are mixed in molar form and reacted for a period of time to prepare a modified curing agent. Finally, a certain proportion of the adhesive solution and the modified curing agent are mixed, an accelerator is added, and the mixture is stirred evenly to obtain a detachable thermally conductive epoxy resin adhesive. The detachable thermally conductive epoxy resin adhesive and preparation method based on dynamic disulfide bonds provided by this invention have the advantages of high bonding strength, insulation, thermal conductivity, and the ability to be disassembled within 80 seconds after high-temperature curing. It has application prospects in electronic components, transducers, photovoltaic bonding, and other fields.

Description

Technical Field

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

[0002] Epoxy resins and curing agents can form a three-dimensional cross-linked solid material at high temperatures. Their excellent mechanical properties, thermal stability, wettability, and adhesion make them important in many industrial applications. However, their stable three-dimensional cross-linked network also makes them difficult to disassemble or reprocess after curing. Incorrect installation or the end of their service life makes them difficult to disassemble, repair, and recycle, leading to resource waste and environmental pollution. Therefore, achieving the disassembly and recyclability of epoxy resins has become an important topic 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 that can undergo reversible reactions under specific conditions; common dynamic bonds include dynamic disulfide bonds, borate ester bonds, and ester bonds. Epoxy resins incorporating dynamic covalent bonds not only enable rapid chemical reactions under specific conditions but also endow the materials with disassembly, 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 based on dynamic disulfide bonds. The core idea is to add pretreated, highly thermally conductive fillers to the epoxy system to improve the thermal conductivity of the epoxy resin adhesive. Then, a bisphenol with dynamic disulfide bonds is introduced into the epoxy-anhydride system. The preferential reaction between the two phenolic hydroxyl groups in the bisphenol monomer and the anhydride promotes the ring-opening reaction of the epoxy resin, thereby forming a bisphenol ester bridging structure in the crosslinking network. Simultaneously, the dynamic disulfide bonds are retained in the molecular backbone, becoming dynamic crosslinking points. By adjusting the content of the bisphenol monomer, the removability of the material can be effectively controlled while maintaining its excellent mechanical properties and thermal stability. 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 dynamic disulfide bonds. This method can reduce the strength of the epoxy resin adhesive after curing at a certain temperature, making it easier to disassemble the bonded material, thereby achieving 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 dynamic disulfide bonds, 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 diphenol with dynamic disulfide bonds and an anhydride to induce ring-opening of the anhydride to 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 product is characterized by: adding an active diluent, such as polyethylene glycol diglycidyl ether, to the epoxy resin at a dosage of 10-30 parts; using ZnO or BN as a thermally conductive filler after surface pretreatment with a silane coupling agent at a dosage of 0-30 parts; adding KH-550 or KH-560 as a silane coupling agent at a dosage of 1-5 wt%; using bis(4-hydroxyphenyl) disulfide as a diphenol with dynamic disulfide bonds; using phthalic anhydride and 4-methylhexahydrophthalic anhydride as acid anhydrides; preparing a modified curing agent by reacting bis(4-hydroxyphenyl) disulfide with acid anhydride at a molar ratio of 0.2-0.6; adding 77.2 wt% of the modified curing agent; adding 1 wt% of the accelerator N'N-dimethylbenzylamine; and curing at high temperature, with the curing conditions being 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 80 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-128), and the mixture was stirred until homogeneous to reduce viscosity. Then, 20 parts of pretreated ZnO (KH-550) were added. 0.2 moles of bis(4-hydroxyphenyl) disulfide 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 7.3 MPa, the adhesive could be removable after 80 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] 20 parts of polyethylene glycol diglycidyl ether were added to 100 parts of epoxy resin (E-128), and the mixture was stirred until homogeneous to reduce viscosity. Then, 20 parts of pretreated ZnO (KH-550) were added. 0.4 moles of bis(4-hydroxyphenyl) disulfide 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 6.7 MPa, the adhesive could be removable in 72 seconds at 140℃, the thermal conductivity was higher than 0.62 W / m·K, and the surface resistivity was greater than 2*10⁻⁶. 9 Ω.

[0016] Example 3

[0017] 20 parts of polyethylene glycol diglycidyl ether were added to 100 parts of epoxy resin (E-128), and the mixture was stirred until homogeneous to reduce viscosity. Then, 20 parts of pretreated ZnO (KH-550) were added. 0.6 moles of bis(4-hydroxyphenyl) disulfide 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 6.5 MPa, the adhesive could be removable in 56 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 dynamic disulfide bonds, characterized in that: The method comprises the following steps: The diluent is added into the epoxy resin, and mixed and stirred to reduce the viscosity of the epoxy resin; the silane coupling agent is added to pre-treat the surface of the heat-conducting filler to improve the heat conductivity; the binary phenol with dynamic disulfide bond and the anhydride are mixed and stirred to react, and the anhydride is induced to open ring to generate carboxylic acid to obtain a modified curing agent; finally, the modified curing agent is added into the diluted epoxy resin glue solution, the accelerator is added, and mixed and stirred to coat and bond the material, and high-temperature curing is performed to realize bonding.

2. The method for preparing a dynamic disulfide bond-based detachable thermal conductive epoxy resin adhesive according to claim 1, characterized in that: The diluent added into the epoxy resin is an active diluent, the active diluent is polyethylene glycol diglycidyl ether, and the addition amount is 10-30 parts.

3. The method for preparing a detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds according to claim 1, characterized in that: The heat-conducting filler pre-treated by the silane coupling agent is ZnO or BN, and the addition amount is 0-30 parts.

4. The method for preparing a detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds according to claim 1, characterized in that: The silane coupling agent is KH-550 or KH-560, and the addition amount is 1-5 wt%.

5. The method for preparing a detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds according to claim 1, characterized in that: The binary phenol with dynamic disulfide bond is bis(4-hydroxyphenyl) disulfide, and the anhydride is phthalic anhydride and 4-methylhexahydrophthalic anhydride.

6. The method of claim 1, wherein the method comprises: (a) mixing the components of the epoxy resin adhesive to form a mixture; (b) heating the mixture to a temperature of about 60 °C to about 80 °C; (c) adding the reducing agent to the mixture; (d) mixing the mixture to form a homogeneous mixture; and (e) cooling the mixture to room temperature. The addition amount of the modified curing agent is 77.2 wt%.

7. The method of claim 1, wherein the method comprises: (a) mixing the components of the epoxy resin adhesive to form a mixture; (b) heating the mixture to a temperature of about 60 °C to about 80 °C; (c) adding the reducing agent to the mixture; (d) mixing the mixture to form a homogeneous mixture; and (e) cooling the mixture to room temperature. The accelerator is N′N-dimethyl benzylamine, and the addition amount is 1 wt%.

8. The method for preparing a detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds according to claim 1, characterized in that: High-temperature curing is performed, the curing condition is that the temperature is increased to 150℃ for 2h after curing at 100℃ for 2h.

9. A preparation method of a detachable heat-conducting epoxy resin adhesive based on dynamic disulfide bond, characterized in that: The adhesive has high bonding strength, insulation, heat conduction, and the adhesive can be detached within 80 seconds after high-temperature treatment and curing.

10. A dynamic disulfide bond based releasable thermal conductive epoxy resin adhesive characterized by: The detachable heat-conducting epoxy resin adhesive is prepared by the preparation method of any one of claims 1 to 9.