Detachable heat-conducting epoxy resin adhesive based on dynamic disulfide bonds and preparation method of detachable heat-conducting epoxy resin adhesive

Abstract

The invention discloses a detachable heat-conducting epoxy resin adhesive based on dynamic disulfide bonds and a preparation method of the detachable heat-conducting epoxy resin adhesive. The method comprises the following steps: firstly, adding a diluent into epoxy resin to reduce the viscosity of the epoxy resin, adding a heat-conducting filler to improve the heat conductivity coefficient, and preparing a glue solution; secondly, diphenol with dynamic disulfide bonds and anhydride are mixed according to molar ratio and react for a period of time, and a modified curing agent is prepared; and finally, mixing the glue solution and the modified curing agent according to a certain proportion, adding the accelerant, and uniformly stirring to obtain the detachable heat-conducting epoxy resin adhesive. According to the detachable heat-conducting epoxy resin adhesive based on the dynamic disulfide bond and the preparation method, the detachable heat-conducting epoxy resin adhesive has the advantages of high bonding strength, insulation, heat conduction and the like, the adhesive can be detached within 80 seconds after high-temperature treatment and curing, and the detachable heat-conducting epoxy resin adhesive has application prospects in the fields of electronic elements, energy transducers, photovoltaic bonding and the like.

Description

Technical Field

[0001] The invention relates to a detachable heat-conductive epoxy resin adhesive based on a dynamic disulfide bond and a preparation method thereof, belonging to the technical field of epoxy resin adhesives. Background Art

[0002] Epoxy resin and curing agent can form a three-dimensional cross-linked solid material at high temperature. Its excellent mechanical properties, thermal stability, wettability and adhesion make it an important material in many industrial applications. However, its stable three-dimensional cross-linked network also makes it difficult to disassemble or reprocess after curing. It cannot be effectively disassembled, repaired and recycled after incorrect installation or at the end of its service life, which leads to resource waste and environmental pollution. Therefore, achieving the disassembly and recyclability of epoxy resin has become an important topic in materials science.

[0003] In recent years, glass-like epoxy resin systems based on dynamic covalent bonds have received widespread attention. Dynamic covalent bonds are chemical bonds that can undergo reversible reactions under specific conditions. Common dynamic bonds include dynamic disulfide bonds, borate bonds, and ester bonds. Epoxy resins with dynamic covalent bonds can not only achieve rapid chemical reactions under specific conditions, but also give the material detachable, self-healing, and recyclable properties.

[0004] The intrinsic thermal conductivity of epoxy resin is low, and adding high thermal conductivity fillers is a common method to improve the thermal conductivity of epoxy resin. Filling with high thermal conductivity fillers can build an effective thermal conduction channel in the epoxy resin matrix and significantly improve the thermal conductivity. The thermal conductivity of filled epoxy resin is mainly affected by the thermal conductivity of the filler, the filling amount and the composite method with the matrix. Due to its simple preparation process and low production cost, filled epoxy resin is widely used in the industrial field.

[0005] The present invention proposes a method for a detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds. The core idea is to add a pretreated high thermal conductivity filler to the epoxy system to improve the thermal conductivity of the epoxy resin adhesive, and then introduce a diphenol with a dynamic disulfide bond into the epoxy-anhydride system. The preferential reaction of the two phenolic hydroxyl groups in the diphenol monomer with the anhydride promotes the ring-opening reaction of the epoxy resin, thereby forming a bisphenol ester bridge structure in the cross-linked network, and retaining the dynamic disulfide bond in the molecular skeleton as a dynamic cross-linking point. By adjusting the content of the diphenol monomer, the detachable performance 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 detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and a preparation method thereof, which can reduce the strength of the epoxy resin adhesive after curing at a certain temperature, facilitate the disassembly of the adhesive material, and thus realize the effective disassembly and recycling of the material.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A detachable heat-conductive epoxy resin adhesive based on dynamic disulfide bonds and a preparation method thereof, characterized in that it comprises the following steps: adding a diluent to the epoxy resin, mixing and stirring evenly to reduce the viscosity of the epoxy resin; then adding a heat-conductive filler after surface pretreatment with a silane coupling agent to improve the thermal conductivity; mixing and stirring a dihydric phenol with a dynamic disulfide bond and an acid anhydride to react, inducing the acid anhydride to open the ring to generate a carboxylic acid to obtain a modified curing agent; finally, adding the modified curing agent to the diluted epoxy resin glue, then adding an accelerator, mixing and stirring evenly, coating it on the bonding material, and curing it at high temperature to achieve bonding.

[0009] The invention is characterized in that: the diluent added to the epoxy resin is preferably an active diluent, such as polyethylene glycol diglycidyl ether, and the preferred addition amount is 10 to 30 parts; the thermal conductive filler after surface pretreatment of the silane coupling agent is preferably ZnO or BN, and the addition amount is 0 to 30 parts; the added silane coupling agent is preferably KH-550 or KH-560, and the addition amount is 1 to 5wt%; the dihydric phenol with dynamic disulfide bonds is preferably bis(4-hydroxyphenyl) disulfide; the acid anhydride is preferably phthalic anhydride and 4-methylhexahydrophthalic anhydride; the reaction molar ratio of bis(4-hydroxyphenyl) disulfide and the acid anhydride is preferably 0.2 to 0.6, and a modified curing agent is prepared; the addition amount of the modified curing agent is preferably 77.2wt%; the preferred accelerator N'N-dimethylbenzylamine is added in an amount of 1wt%; high-temperature curing molding, the curing conditions are curing at 100°C for 2h, and curing at a temperature increased to 150°C for 2h.

[0010] The beneficial effects of the present invention are as follows: the adhesive has the advantages of high bonding strength, insulation, heat conduction, etc., and the adhesive can be disassembled within 80 seconds after being cured by high-temperature treatment. DETAILED DESCRIPTION

[0011] The present invention is further described in detail below in conjunction with implementation examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope 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), mixed and stirred evenly, the viscosity was reduced, and mixed and stirred evenly; then 20 parts of KH-550 pretreated ZnO were added; 0.2 moles of bis(4-hydroxyphenyl) disulfide were added to 1 mole of 4-methylhexahydrophthalic anhydride, stirred to react, and the anhydride was induced to open the ring to generate carboxylic acid to obtain a modified curing agent; finally, 75 parts of the curing agent were added to 100 parts of epoxy resin glue, and then 1 part of N'N-dimethylbenzylamine was added, mixed and stirred evenly to obtain a detachable thermally conductive epoxy adhesive; aluminum sheet was used as the bonding object, first cured at 100°C for 2h, and then cured at 150°C for 2h, and the shear strength was measured to be 7.3MPa, detachable at 140°C for 80 seconds, the thermal conductivity was higher than 0.60W / m·K, and the surface resistance was greater than 2*10 9 Ω.

[0014] Example 2

[0015] 20 parts of polyethylene glycol diglycidyl ether were added to 100 parts of epoxy resin (E-128), mixed and stirred evenly, the viscosity was reduced, and mixed and stirred evenly; then 20 parts of KH-550 pretreated ZnO were added; 0.4 moles of bis(4-hydroxyphenyl) disulfide were added to 1 mole of 4-methylhexahydrophthalic anhydride, stirred to react, and the anhydride was induced to open the ring to generate carboxylic acid to obtain a modified curing agent; finally, 75 parts of the curing agent were added to 100 parts of epoxy resin glue, and then 1 part of N'N-dimethylbenzylamine was added, mixed and stirred evenly to obtain a detachable thermally conductive epoxy adhesive; aluminum sheet was used as the bonding object, first cured at 100°C for 2h, and then cured at 150°C for 2h, and the shear strength was measured to be 6.7MPa, detachable at 140°C for 72 seconds, the thermal conductivity was higher than 0.62W / m·K, and the surface resistance was 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-128), mixed and stirred evenly, the viscosity was reduced, and mixed and stirred evenly; then 20 parts of KH-550 pretreated ZnO were added; 0.6 moles of bis(4-hydroxyphenyl) disulfide were added to 1 mole of 4-methylhexahydrophthalic anhydride, stirred to react, and the anhydride was induced to open the ring to generate carboxylic acid to obtain a modified curing agent; finally, 75 parts of the curing agent were added to 100 parts of epoxy resin glue, and then 1 part of N'N-dimethylbenzylamine was added, mixed and stirred evenly to obtain a detachable thermally conductive epoxy adhesive; aluminum sheet was used as the bonding object, first cured at 100°C for 2h, and then cured at 150°C for 2h, and the shear strength was measured to be 6.5MPa, detachable at 140°C for 56 seconds, the thermal conductivity was higher than 0.83W / m·K, and the surface resistance was greater than 2*10 9 Ω.

[0018] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and a preparation method thereof, characterized in that: The following steps are involved: Add diluent to epoxy resin, mix and stir evenly to reduce the viscosity of epoxy resin; then add silane coupling agent to pre-treat the surface of thermal conductive filler to improve thermal conductivity; mix and stir diphenol with dynamic disulfide bond and acid anhydride to react, induce the acid anhydride to open the ring to generate carboxylic acid to obtain modified curing agent; finally, add the modified curing agent to the diluted epoxy resin glue, add accelerator, mix and stir evenly, apply to the adhesive material, and cure at high temperature to achieve bonding.

2. A detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and a preparation method thereof according to claim 1, characterized in that: The diluent added to the epoxy resin is preferably a reactive diluent, such as polyethylene glycol diglycidyl ether, and the preferred addition amount is 10 to 30 parts.

3. The detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and the preparation method thereof according to claim 1, characterized in that: After the surface of the silane coupling agent is pretreated, the thermal conductive filler is preferably ZnO or BN, and the addition amount is 0 to 30 parts.

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

5. The detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and the preparation method thereof according to claim 1, characterized in that: The diphenol with dynamic disulfide bonds is preferably bis(4-hydroxyphenyl) disulfide; the acid anhydride is preferably phthalic anhydride and 4-methylhexahydrophthalic anhydride; the reaction molar ratio of bis(4-hydroxyphenyl) disulfide to the acid anhydride is preferably 0.2-0.6, and the modified curing agent is prepared.

6. The detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and the preparation method thereof according to claim 1, characterized in that: The added amount of the modified curing agent is preferably 77.2 wt %.

7. The detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and the preparation method thereof according to claim 1, characterized in that: The preferred accelerator is N'N-dimethylbenzylamine, which is added in an amount of 1 wt%.

8. The detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and the preparation method thereof according to claim 1, characterized in that: High temperature curing molding, the curing conditions are curing at 100℃ for 2h, and then curing at 150℃ for 2h.

9. A detachable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds and a preparation method thereof, characterized in that: The adhesive has the advantages of high bonding strength, insulation, thermal conductivity, etc. After high-temperature treatment and curing, the adhesive can be disassembled within 80 seconds.

10. A removable thermally conductive epoxy resin adhesive based on dynamic disulfide bonds, characterized in that: The detachable epoxy resin adhesive is prepared by the preparation method of any one of claims 1 to 9.