Heat-conducting silica gel material and preparation method thereof

Abstract

The invention belongs to the technical field of heat-conducting materials, and particularly relates to a heat-conducting silica gel material and a preparation method thereof.The heat-conducting silica gel material is prepared from, by weight, 20-25 parts of self-healing epoxy resin, 50-60 parts of silica gel, 10-15 parts of GO, 5-10 parts of CNT, 0.5-2 parts of dispersing agent and 2-5 parts of curing agent; the self-healing epoxy resin is prepared from vulcanization-modified epoxy resin and microcapsules containing a repairing agent, introduced disulfide bonds have extremely high self-repairing capacity and can form hydroxyl groups with GO and CNT surface oxidation groups at the same time, so that heat conduction and heat dissipation of the silica gel material are more uniform and stable, and in addition, the self-healing epoxy resin has good self-healing performance. The added GO and CNT form cross-linked structures with different sizes of nanometer and micrometer, so that the overall mechanical strength and tensile property of the silica gel material are further improved, the optimal balance of hardness, toughness and thermal stability can be realized, and multiple requirements in a complex working environment are met.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal conductive materials, and in particular relates to a thermal conductive silicone material and a preparation method thereof. Technical Background

[0002] As the power density of electronic devices continues to increase, heat dissipation issues are increasingly becoming a key factor restricting their performance and lifespan. As an important heat dissipation material, thermally conductive silicone is widely used in LED lighting, communication equipment, automotive electronics and other fields due to its excellent flexibility, good electrical insulation and high temperature resistance. Traditional thermally conductive silicone mainly relies on fillers such as aluminum nitride and silicon dioxide to improve thermal conductivity, but due to the poor dispersibility of these fillers, there are still certain limitations in mechanical strength and long-term stability, making it difficult to meet the heat dissipation requirements of high power density equipment.

[0003] Therefore, finding new high thermal conductivity materials and developing thermally conductive silicone materials with high thermal conductivity, good mechanical properties, stability and environmental protection have become the focus of current research and development. Summary of the invention

[0004] In view of the above situation, the present invention provides a thermally conductive silicone material and a preparation method thereof, wherein a self-healing epoxy resin is compounded with a silicone matrix, the mechanical strength and heat resistance thereof are enhanced through cross-linking, polymer molecules with enhanced thermal conductivity properties are added to enhance interface affinity, and fillers of different sizes are combined to achieve a multi-level thermal conductive channel structure at the nanoscale and microscale, so that heat can be conducted more efficiently in the material.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The invention provides a thermally conductive silicone material, which comprises the following raw materials in parts by weight: 20-25 parts of a self-healing epoxy resin, 50-60 parts of silicone, 10-15 parts of GO (graphene oxide), 5-10 parts of CNT (carbon nanotube), 0.5-2 parts of a dispersant and 2-5 parts of a curing agent.

[0006] Furthermore, the self-healing epoxy resin comprises the following raw materials in parts by weight: 25-40 parts of DGEBA (bisphenol A diglycidyl ether), 0.5-3 parts of BPF (bisphenol F diglycidyl ether) resin, 2-5 parts of microcapsules, 2-5 parts of disulfide and 2-7 parts of alkenyl compounds.

[0007] Furthermore, the silicone is selected from one or more of RTV (room temperature vulcanized) silicone, HTV (high temperature vulcanized) silicone, LSP (liquid) silicone, VMQ (methyl vinyl) silicone, preferably RTV silicone.

[0008] Furthermore, the CNT is a single-layer carbon nanotube.

[0009] Furthermore, the dispersant is selected from one or more of PVA (polyvinyl alcohol), PVP (polyvinyl pyrrolidone), and PDMS (polydimethylsiloxane), preferably PVA17-92 among PVA.

[0010] Furthermore, the curing agent is selected from one or more of BPO (benzoyl peroxide), platinum chloride, maleic anhydride, and 2-AFD (2-aminophenyl disulfide).

[0011] Furthermore, the microcapsule material is selected from one or more of PU (polyurethane), PAA (polyacrylic acid), and PLA (polylactic acid), preferably PU.

[0012] Furthermore, the disulfide is selected from one or more of 3,3'-dimethyl dithiodipropionate, 4,4'-diaminodiphenyl disulfide, and DL-dithiothreitol.

[0013] Furthermore, the alkenyl compound is selected from one or more of 1,4-cyclohexadiene, 1-octadecene, acrylamide, and methyl methacrylate, preferably 1,4-cyclohexadiene.

[0014] Furthermore, the epoxy value of DGEBA is 0.51-0.54.

[0015] The preparation method of the self-healing epoxy resin comprises the following steps: S1: Weigh 25-40 parts of DGEBA, heat to 60-80°C, and stir at 100 rpm on a magnetic stirrer for 5 min to obtain an activated epoxy resin; S2: Weigh 2-5 parts of disulfide and 2-7 parts of alkenyl compound and add them to the activated epoxy resin obtained in step S1, stir at 80-85° C. for 1 h at a stirring speed of 150 rpm to carry out a vulcanization reaction to obtain a vulcanized epoxy resin; S3: Weigh 2-5 parts of microcapsule material and dissolve them in 5 times the mass of purified water to obtain a microcapsule material solution, weigh 0.5-3 parts of BPF resin and slowly add them to the microcapsule material solution, heat to 60-80°C, stir at 100 rpm for 30 min to obtain a co-gel solution, and dry in a vacuum drying oven at 60°C for 4 h to obtain microcapsules; S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, dispersing in an ultrasonic disperser for 2 min, with a power of 120 W, ultrasound for 5 s, and an interval of 3 s to obtain a self-healing epoxy resin.

[0016] The present invention also provides a method for preparing a thermally conductive silicone material, which specifically comprises the following steps: Step 1: Weigh 10-15 parts of GO and dissolve them in purified water at a mass volume ratio of 1 g: 5 mL to obtain a GO solution; weigh 5-10 parts of CNT and dissolve them in DMF (N,N-dimethylformamide) at a mass volume ratio of 1 g: 3 mL to obtain a CNT solution; mix the GO solution and the CNT solution to obtain a mixed solution; weigh 0.5-2 parts of a dispersant and add it to the mixed solution; disperse it in an ultrasonic disperser for 5 min, with a power of 120 W, ultrasonic for 5 s, and an interval of 3 s to obtain a filler matrix solution; Step 2: Weigh 20-25 parts of self-healing epoxy resin and 50-60 parts of silicone, mix them, heat to 60-80°C, stir them at 3600 rpm using a high shear stirrer for 20 min, then weigh 2-5 parts of curing agent and add them, continue stirring for 5 min to obtain a uniform and viscous mixture; Step 3: slowly add the filler matrix solution obtained in step 1 to the mixture obtained in step 2, stir at 3600 rpm in a high shear stirrer at 60-80° C. for 30 min, and mix thoroughly to obtain a silica composite matrix; Step 4: Transfer the silica gel composite matrix obtained in step 3 to a 60°C vacuum drying oven for degassing for 15 min, pour it into a preheated mold, and cure it in an oven at 110°C / 1 h+150°C / 2 h (drying at 110°C for 1 h, then drying at 150°C for 2 h) to obtain a thermally conductive silica gel material.

[0017] The beneficial effects achieved by the present invention are as follows: The thermally conductive silicone material prepared by the present invention significantly improves the thermal conductivity of the composite material by adding self-healing epoxy resin, nano-scale GO, and CNT high thermal conductivity filler to the micron-grade silicone material. There are a large number of oxidized groups and pores on the surface of GO and CNT, which can form a strong interface bond with the silicone material and epoxy resin, making the thermal conductivity and heat dissipation more uniform and efficient. At the same time, the long fiber structure of CNT enhances the mechanical strength and tensile resistance of the silicone material, providing good thermal conductivity and electrical conductivity. The introduction of materials of different sizes allows the thermal conductivity and mechanical properties of silicone to be precisely controlled to meet the needs of different application scenarios. The hardness, toughness and thermal stability of the material can achieve an optimal balance to meet multiple needs in a complex working environment. In the self-healing epoxy resin material, disulfide bonds are introduced into the epoxy resin, so that when the silicone material is deformed or broken, the reversible reaction of the disulfide bonds can obtain a dynamic covalent structure, realize the repolymerization of the epoxy resin, and spontaneously run the repair mechanism without the need for additional catalysts or external conditions. It has recyclable and self-healing properties. Among them, the repair agent wrapped by the microcapsule provides a second guarantee mechanism for the fracture repair of the silicone material. When the modified epoxy resin cannot reach the self-healing conditions, the microcapsule will release the repair agent to promote the formation of epoxy resin polymers. In addition to catalyzing the synthesis of modified epoxy resins, disulfides can also work with the added curing agent to enhance the toughness and flexibility of the material. This self-healing ability significantly improves the durability of the material in long-term use and reduces the performance degradation caused by damage. It is particularly suitable for high-performance material fields that require high reliability and long-term stability, such as aerospace, automobiles and electronic equipment, which greatly facilitates production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the self-healing reaction principle of the modified epoxy resin and the preparation of the thermal conductive silicone material of the present invention; Figure 2 Thermogravimetric analysis results of thermally conductive silica gel materials prepared in Example 1, Example 4, Example 5 and Comparative Examples 1-3; Figure 3 The thermal expansion and thermal conductivity test results of the thermally conductive silicone materials prepared in Example 1, Example 4, Example 5 and Comparative Examples 1-3; Figure 4 This is a diagram showing the self-healing stretching effect of the thermally conductive silicone material prepared in Example 1 after being cut; Figure 5 The resistivity test results of the thermally conductive silicone materials prepared in Example 1, Example 4, Example 5 and Comparative Examples 1-3; Figure 6 The dielectric constant and breakdown voltage test results of the thermally conductive silicone materials prepared in Example 1, Example 4, Example 5 and Comparative Examples 1-3.

[0019] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0022] In the following embodiments, the preparation process of the thermally conductive silicone material is as follows Figure 1 Unless otherwise specified, all methods are conventional; the materials used in the following embodiments, unless otherwise specified, are new materials purchased from the market.

[0023] Example 1: The present invention provides a thermally conductive silicone material, which comprises the following raw materials in parts by weight: 20 parts of self-healing epoxy resin, 50 parts of RTV silicone, 10 parts of GO, 5 parts of CNT, 0.5 parts of PVA17-92 and 2 parts of 2-AFD.

[0024] The self-healing epoxy resin comprises the following raw materials in parts by weight: 25 parts of DGEBA, 0.5 parts of BPF resin, 2 parts of PU, 2 parts of 4,4'-diaminodiphenyl disulfide and 2 parts of 1,4-cyclohexadiene. The specific preparation method is as follows: S1: Weigh 25 parts of DGEBA, heat to 80°C, and stir at 100 rpm on a magnetic stirrer for 5 min to obtain an activated epoxy resin; S2: Weigh 2 parts of 4,4'-diaminodiphenyl disulfide and 2 parts of 1,4-cyclohexadiene and add them to the activated epoxy resin obtained in step S1, stir at 85°C for 1 h, and stir at a speed of 150 rpm to perform a vulcanization reaction to obtain a vulcanized epoxy resin; S3: Weigh 2 parts of PU and dissolve them in 5 times the mass of purified water to obtain a PU solution. Weigh 0.5 parts of BPF resin and slowly add it to the PU solution. Heat to 60°C and stir at 100 rpm for 30 min to obtain a co-gel solution. Dry it in a vacuum drying oven at 60°C for 4 h to obtain microcapsules. S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, dispersing in an ultrasonic disperser for 2 min, with a power of 120 W, ultrasound for 5 s, and an interval of 3 s to obtain a self-healing epoxy resin.

[0025] The present invention also provides a method for preparing a thermally conductive silicone material, which specifically comprises the following steps: Step 1: Weigh 10 parts of GO and dissolve them in purified water at a mass volume ratio of 1 g: 5 mL to obtain a GO solution; weigh 8 parts of CNT and dissolve them in DMF at a mass volume ratio of 1 g: 3 mL to obtain a CNT solution; mix the GO solution and the CNT solution to obtain a mixed solution; weigh 0.5 parts of PVA17-92 and add it to the mixed solution; disperse it in an ultrasonic disperser for 5 min, with a power of 120 W, ultrasonic for 5 s, and an interval of 3 s to obtain a filler matrix solution; Step 2: Weigh 20 parts of self-healing epoxy resin and 50 parts of RTV silicone, mix them, heat to 80°C, stir them at 3600 rpm using a high shear mixer for 20 min, weigh 2 parts of 2-AFD and add them, continue stirring for 5 min to obtain a uniform and viscous mixture; Step 3: slowly add the filler matrix solution obtained in step 1 to the mixture obtained in step 2, stir at 3600 rpm in a high shear stirrer at 60° C. for 30 min, and mix thoroughly to obtain a silica composite matrix; Step 4: Transfer the silica gel composite matrix obtained in step 3 to a 60°C vacuum drying oven for degassing for 15 min, pour it into a preheated mold, and cure it in an oven at 110°C / 1 h+150°C / 2 h to obtain a thermally conductive silica gel material.

[0026] Example 2: The present invention provides a thermally conductive silicone material, which comprises the following raw materials in parts by weight: 22 parts of self-healing epoxy resin, 55 parts of RTV silicone, 12 parts of GO, 8 parts of CNT, 1 part of PVA17-92 and 3 parts of 2-AFD.

[0027] The self-healing epoxy resin comprises the following raw materials in parts by weight: 30 parts of DGEBA, 1.5 parts of BPF resin, 3 parts of PU, 3 parts of 4,4'-diaminodiphenyl disulfide and 5 parts of 1,4-cyclohexadiene. The specific preparation method is as follows: S1: Weigh 30 parts of DGEBA, heat to 70°C, and stir at 100 rpm on a magnetic stirrer for 5 min to obtain an activated epoxy resin; S2: Weigh 3 parts of 4,4'-diaminodiphenyl disulfide and 5 parts of 1,4-cyclohexadiene and add them to the activated epoxy resin obtained in step S1, stir at 80°C for 1 h at a stirring speed of 150 rpm to perform a vulcanization reaction to obtain a vulcanized epoxy resin; S3: Weigh 3 parts of PU and dissolve them in 5 times the mass of purified water to obtain a PU solution. Weigh 1.5 parts of BPF resin and slowly add them to the PU solution. Heat to 60°C and stir at 100 rpm for 30 min to obtain a co-gel solution. Dry in a vacuum drying oven at 60°C for 4 h to obtain microcapsules. S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, dispersing in an ultrasonic disperser for 2 min, with a power of 120 W, ultrasound for 5 s, and an interval of 3 s to obtain a self-healing epoxy resin.

[0028] The present invention also provides a method for preparing a thermally conductive silicone material, which specifically comprises the following steps: Step 1: Weigh 12 parts of GO and dissolve them in purified water at a mass volume ratio of 1 g: 5 mL to obtain a GO solution; weigh 8 parts of CNT and dissolve them in DMF at a mass volume ratio of 1 g: 3 mL to obtain a CNT solution; mix the GO solution and the CNT solution to obtain a mixed solution; weigh 1 part of PVA17-92 and add it to the mixed solution; disperse it in an ultrasonic disperser for 5 min, with a power of 120 W, ultrasonic for 5 s, and an interval of 3 s to obtain a filler matrix solution; Step 2: Weigh 22 parts of self-healing epoxy resin and 55 parts of RTV silicone, mix them, heat to 80°C, stir them at 3600 rpm using a high shear mixer for 20 min, weigh 3 parts of 2-AFD and add them, continue stirring for 5 min to obtain a uniform and viscous mixture; Step 3: slowly add the filler matrix solution obtained in step 1 to the mixture obtained in step 2, stir at 3600 rpm in a high shear stirrer at 60° C. for 30 min, and mix thoroughly to obtain a silica composite matrix; Step 4: Transfer the silica gel composite matrix obtained in step 3 to a 60°C vacuum drying oven for degassing for 15 min, pour it into a preheated mold, and cure it in an oven at 110°C / 1 h+150°C / 2 h to obtain a thermally conductive silica gel material.

[0029] Example 3: The present invention provides a thermally conductive silicone material, which comprises the following raw materials in parts by weight: 25 parts of self-healing epoxy resin, 60 parts of RTV silicone, 15 parts of GO, 10 parts of CNT, 2 parts of PVA17-92 and 5 parts of 2-AFD.

[0030] The self-healing epoxy resin comprises the following raw materials in parts by weight: 40 parts of DGEBA, 3 parts of BPF resin, 5 parts of PU, 5 parts of 4,4'-diaminodiphenyl disulfide and 7 parts of 1,4-cyclohexadiene. The specific preparation method is as follows: S1: Weigh 40 parts of DGEBA, heat to 60°C, and stir at 100 rpm on a magnetic stirrer for 5 min to obtain an activated epoxy resin; S2: Weigh 5 parts of 4,4'-diaminodiphenyl disulfide and 7 parts of 1,4-cyclohexadiene and add them to the activated epoxy resin obtained in step S1, stir at 85°C for 1 h, and stir at a speed of 150 rpm to perform a vulcanization reaction to obtain a vulcanized epoxy resin; S3: Weigh 5 parts of PU and dissolve them in 5 times the mass of purified water to obtain a PU solution. Weigh 3 parts of BPF resin and slowly add them to the PU solution. Heat to 60°C and stir at 100 rpm for 30 min to obtain a co-gel solution. Dry in a vacuum drying oven at 60°C for 4 h to obtain microcapsules. S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, dispersing in an ultrasonic disperser for 2 min, with a power of 120 W, ultrasound for 5 s, and an interval of 3 s to obtain a self-healing epoxy resin.

[0031] The present invention also provides a method for preparing a thermally conductive silicone material, which specifically comprises the following steps: Step 1: Weigh 15 parts of GO and dissolve them in purified water at a mass volume ratio of 1 g: 5 mL to obtain a GO solution; weigh 10 parts of CNT and dissolve them in DMF at a mass volume ratio of 1 g: 3 mL to obtain a CNT solution; mix the GO solution and the CNT solution to obtain a mixed solution; weigh 2 parts of PVA17-92 and add them to the mixed solution; disperse them in an ultrasonic disperser for 5 min, with a power of 120 W, ultrasonic for 5 s, and an interval of 3 s to obtain a filler matrix solution; Step 2: Weigh 25 parts of self-healing epoxy resin and 60 parts of RTV silicone, mix them, heat to 80°C, stir them at 3600 rpm using a high shear mixer for 20 min, weigh 5 parts of 2-AFD and add them, continue stirring for 5 min to obtain a uniform and viscous mixture; Step 3: slowly add the filler matrix solution obtained in step 1 to the mixture obtained in step 2, stir at 3600 rpm in a high shear stirrer at 60° C. for 30 min, and mix thoroughly to obtain a silica composite matrix; Step 4: Transfer the silica gel composite matrix obtained in step 3 to a 60°C vacuum drying oven for degassing for 15 min, pour it into a preheated mold, and cure it in an oven at 110°C / 1 h+150°C / 2 h to obtain a thermally conductive silica gel material.

[0032] In order to study the effect of adding different curing agents and disulfides on the thermal conductivity, heat dissipation, mechanical strength and tensile strength of the prepared thermally conductive silicone material, the following examples refer to the raw material ratio and preparation method of Example 1, and replace the curing agent 2-AFD with BPO and maleic anhydride, and replace the disulfide 4,4'-diaminodiphenyl disulfide with 3,3'-dimethyl dithiodipropionate and DL-dithiothreitol to prepare the thermally conductive silicone material.

[0033] Example 4: The present invention provides a thermally conductive silicone material, which comprises the following raw materials in parts by weight: 20 parts of self-healing epoxy resin, 50 parts of RTV silicone, 10 parts of GO, 5 parts of CNT, 0.5 parts of PVA17-92 and 2 parts of BPO.

[0034] The self-healing epoxy resin comprises the following raw materials in parts by weight: 25 parts of DGEBA, 0.5 parts of BPF resin, 2 parts of PU, 2 parts of dimethyl 3,3'-dithiodipropionate and 2 parts of 1,4-cyclohexadiene. The specific preparation method is as follows: S1: Weigh 25 parts of DGEBA, heat to 80°C, and stir at 100 rpm on a magnetic stirrer for 5 min to obtain an activated epoxy resin; S2: Weigh 2 parts of dimethyl 3,3'-dithiodipropionate and 2 parts of 1,4-cyclohexadiene and add them to the activated epoxy resin obtained in step S1, stir at 85°C for 1 h at a stirring speed of 150 rpm to carry out a vulcanization reaction to obtain a vulcanized epoxy resin; S3: Weigh 2 parts of PU and dissolve them in 5 times the mass of purified water to obtain a PU solution. Weigh 0.5 parts of BPF resin and slowly add it to the PU solution. Heat to 60°C and stir at 100 rpm for 30 min to obtain a co-gel solution. Dry it in a vacuum drying oven at 60°C for 4 h to obtain microcapsules. S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, dispersing in an ultrasonic disperser for 2 min, with a power of 120 W, ultrasound for 5 s, and an interval of 3 s to obtain a self-healing epoxy resin.

[0035] The present invention also provides a method for preparing a thermally conductive silicone material, which specifically comprises the following steps: Step 1: Weigh 10 parts of GO and dissolve them in purified water at a mass volume ratio of 1 g: 5 mL to obtain a GO solution; weigh 8 parts of CNT and dissolve them in DMF at a mass volume ratio of 1 g: 3 mL to obtain a CNT solution; mix the GO solution and the CNT solution to obtain a mixed solution; weigh 0.5 parts of PVA17-92 and add it to the mixed solution; disperse it in an ultrasonic disperser for 5 min, with a power of 120 W, ultrasonic for 5 s, and an interval of 3 s to obtain a filler matrix solution; Step 2: Weigh 20 parts of self-healing epoxy resin and 50 parts of RTV silicone, mix them, heat to 80°C, stir them at 3600 rpm using a high shear mixer for 20 min, weigh 2 parts of BPO and add them, continue stirring for 5 min to obtain a uniform viscous mixture; Step 3: slowly add the filler matrix solution obtained in step 1 to the mixture obtained in step 2, stir at 3600 rpm in a high shear stirrer at 60° C. for 30 min, and mix thoroughly to obtain a silica composite matrix; Step 4: Transfer the silica gel composite matrix obtained in step 3 to a 60°C vacuum drying oven for degassing for 15 min, pour it into a preheated mold, and cure it in an oven at 110°C / 1 h+150°C / 2 h to obtain a thermally conductive silica gel material.

[0036] Example 5: The present invention provides a thermally conductive silicone material, which comprises the following raw materials in parts by weight: 20 parts of self-healing epoxy resin, 50 parts of RTV silicone, 10 parts of GO, 5 parts of CNT, 0.5 parts of PVA17-92 and 2 parts of maleic anhydride.

[0037] The self-healing epoxy resin comprises the following raw materials in parts by weight: 25 parts of DGEBA, 0.5 parts of BPF resin, 2 parts of PU, 2 parts of DL-dithiothreitol and 2 parts of 1,4-cyclohexadiene. The specific preparation method is as follows: S1: Weigh 25 parts of DGEBA, heat to 80°C, and stir at 100 rpm on a magnetic stirrer for 5 min to obtain an activated epoxy resin; S2: Weigh 2 parts of DL-dithiothreitol and 2 parts of 1,4-cyclohexadiene and add them to the activated epoxy resin obtained in step S1, stir at 85° C. for 1 h at a stirring speed of 150 rpm to perform a vulcanization reaction to obtain a vulcanized epoxy resin; S3: Weigh 2 parts of PU and dissolve them in 5 times the mass of purified water to obtain a PU solution. Weigh 0.5 parts of BPF resin and slowly add it to the PU solution. Heat to 60°C and stir at 100 rpm for 30 min to obtain a co-gel solution. Dry it in a vacuum drying oven at 60°C for 4 h to obtain microcapsules. S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, dispersing in an ultrasonic disperser for 2 min, with a power of 120 W, ultrasound for 5 s, and an interval of 3 s to obtain a self-healing epoxy resin.

[0038] The present invention also provides a method for preparing a thermally conductive silicone material, which specifically comprises the following steps: Step 1: Weigh 10 parts of GO and dissolve them in purified water at a mass volume ratio of 1 g: 5 mL to obtain a GO solution; weigh 8 parts of CNT and dissolve them in DMF at a mass volume ratio of 1 g: 3 mL to obtain a CNT solution; mix the GO solution and the CNT solution to obtain a mixed solution; weigh 0.5 parts of PVA17-92 and add it to the mixed solution; disperse it in an ultrasonic disperser for 5 min, with a power of 120 W, ultrasonic for 5 s, and an interval of 3 s to obtain a filler matrix solution; Step 2: Weigh 20 parts of self-healing epoxy resin and 50 parts of RTV silicone, mix them, heat to 80°C, stir them at 3600 rpm using a high shear stirrer for 20 min, weigh 2 parts of maleic anhydride and add them, continue stirring for 5 min, and obtain a uniform viscous mixture; Step 3: slowly add the filler matrix solution obtained in step 1 to the mixture obtained in step 2, stir at 3600 rpm in a high shear stirrer at 60° C. for 30 min, and mix thoroughly to obtain a silica composite matrix; Step 4: Transfer the silica gel composite matrix obtained in step 3 to a 60°C vacuum drying oven for degassing for 15 min, pour it into a preheated mold, and cure it in an oven at 110°C / 1 h+150°C / 2 h to obtain a thermally conductive silica gel material.

[0039] The difference between Comparative Example 1 and Example 1 is that the self-healing epoxy resin is replaced with RTV epoxy resin, and the rest is the same as Example 1; The difference between Comparative Example 2 and Example 1 is that GO is not added, and the rest is the same as Example 1; The difference between Comparative Example 3 and Example 1 is that no CNT is added, and the rest is the same as Example 1.

[0040] Thermal conductivity test Take the thermally conductive silica gel materials prepared in Example 1, Example 4, Example 5 and Comparative Examples 1-3, and use a thermal analyzer to perform thermogravimetric analysis (TGA), nitrogen atmosphere, heating rate 10°C / min, temperature range from room temperature to 800°C; use a thermomechanical analyzer to test the thermal expansion coefficient (CTE), the sample size is 6 mm×6 mm×20 mm, the test temperature is from 25-150°C, the heating rate is 1°C / min; use a laser thermal conductivity meter to test the thermal conductivity, the cylindrical sample radius is 12.7 mm, and the thickness is in the range of 0.8-2.2 mm. TGA results are shown in Figure 2 ; CTE results and thermal conductivity results are shown in Figure 3 .

[0041] Mechanical properties inspection The thermally conductive silicone material prepared in Example 1 was cut in the middle and placed at 60°C for 2 h to examine its healing condition. The results are shown in Figure 4 . Take the thermally conductive silicone materials prepared in Examples 1-5 and Comparative Examples 1-3, and use a tablet tester to cut the prepared silicone sheets into dumbbell-shaped specimens of the national standard. After measuring the thickness, use a universal specimen tester to test the tensile strength and elongation at break; the same instrument is used to test the tearing performance, cut into a right angle, and the stretching speed is 500 mm / min. The self-healing rate of the thermally conductive silicone material is calculated by a scratch recovery test. A hardness tester is used to test the hardness of the sample, and the average value is calculated by multiple measurements. The results are shown in Table 1.

[0042] Electrical performance inspection Take the thermally conductive silicone materials prepared in Example 1, Example 4, Example 5 and Comparative Examples 1-3, and use the E4339B type high resistance meter for volume resistivity and surface resistivity testing, with a disc sample diameter of 55±5 mm. The dielectric loss D and dielectric loss tanδ tests are tested using the precision LCR bridge E4980A and 16451B fixture. The sample size is the same as that for the resistivity test. The measurement frequency range is 20 Hz-2 MHz, and the dielectric constant ε is calculated. The breakdown voltage strength is measured using a voltage resistance breakdown strength tester. The voltage value at which the sample is broken down at a certain voltage is gradually increased, and the breakdown voltage strength can be calculated by dividing it by the thickness, expressed in kV / mm. The resistivity test results are shown in Figure 5 ; Dielectric constant and breakdown voltage results are shown in Figure 6 .

[0043] Figure 2 The TGA results show that the weight loss rates of the thermally conductive silicone materials prepared in Example 1, Example 4 and Example 5 at 100°C are all less than 0.1%, indicating that the added material has good thermal stability. When the weight loss is 5%, the temperatures of Example 1, Example 4, Example 5 and Comparative Examples 1-3 are 472°C, 403°C, 367°C, 301°C, 248°C and 202°C, respectively, indicating that the thermal degradation rate of the thermally conductive silicone materials prepared in Example 1, Example 4 and Example 5 can be effectively controlled.

[0044] Figure 3 The results show that compared with comparative examples 1-3, the thermally conductive silicone materials prepared in Example 1, Example 4 and Example 5 have low thermal expansion coefficients and improved thermal conductivity, indicating that self-healing epoxy resin, GO and CNT as filling materials have good thermal conductivity and stability.

[0045] Table 1 Mechanical properties of thermal conductive silicone materials

[0046] The results in Table 1 show that the tensile strength and self-healing rate of the thermally conductive silicone materials prepared in Examples 1-5 are significantly improved compared with those in Comparative Examples 1-3, especially the self-healing results. After the scratches are repaired, they still have considerable thermal conductivity and tensile strength.

[0047] Figure 4 The results show that the thermally conductive silicone material prepared in Example 1 has strong self-healing ability, and has high strain and compressive strength after healing.

[0048] Figure 5 and Figure 6 The results show that the thermally conductive silicone materials prepared in Example 1, Example 4 and Example 5 have lower resistivity and breakdown voltage. In addition, the dielectric constant test results of Comparative Examples 1-3, Example 1, Example 4 and Example 5 are all less than 7, all showing good insulation properties. Among them, the thermally conductive silicone material with self-healing epoxy resin added as filler has stronger insulation effect and better performance.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0050] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A thermally conductive silicone material, characterized in that: The thermally conductive silicone material comprises the following raw materials in parts by weight: 20-25 parts of self-healing epoxy resin, 50-60 parts of silicone, 10-15 parts of GO, 5-10 parts of CNT, 0.5-2 parts of dispersant and 2-5 parts of curing agent; The self-healing epoxy resin comprises the following raw materials: DGEBA, BPF resin, microcapsule material, disulfide and olefinic compound, and the specific preparation method is as follows: S1: Weigh DGEBA, heat and stir to obtain activated epoxy resin; S2: Weighing a disulfide and an alkenyl compound, adding them to the activated epoxy resin obtained in step S1, heating and stirring, and reacting to obtain a vulcanized epoxy resin; S3: weighing microcapsule material and dissolving it in purified water to obtain a microcapsule material solution, weighing BPF resin and slowly adding it to the microcapsule material solution, heating and stirring to obtain a co-gel solution, and drying to obtain microcapsules; S4: adding the microcapsules obtained in step S3 to the vulcanized epoxy resin obtained in step S2, and performing ultrasonic dispersion to obtain a self-healing epoxy resin.

2. A thermally conductive silicone material according to claim 1, characterized in that: The weight proportions of the DGEBA, BPF resin, microcapsule material, disulfide and olefinic compound are 25-40 parts, 0.5-3 parts, 2-5 parts, 2-5 parts and 2-7 parts respectively; The heating temperature in steps S1 and S3 is 60-80°C, and the heating temperature in step S2 is 80-85°C; In step S3, the mass ratio of the microcapsule material to the purified water is 1:

5.

3. A thermally conductive silicone material according to claim 1, characterized in that: The silica gel is selected from one or more of RTV silica gel, HTV silica gel, LSP silica gel and VMQ silica gel.

4. A thermally conductive silicone material according to claim 1, characterized in that: The dispersant is selected from one or more of PVA, PVP, and PDMS; The curing agent is selected from one or more of BPO, platinum chloride, maleic anhydride and 2-AFD.

5. The thermally conductive silicone material according to claim 1, characterized in that: The microcapsule material is selected from one or more of PU, PAA, and PLA; The disulfide is selected from one or more of 3,3'-dimethyl dithiodipropionate, 4,4'-diaminodiphenyl disulfide, and DL-dithiothreitol; The alkenyl compound is selected from one or more of 1,4-cyclohexadiene, 1-octadecene, acrylamide and methyl methacrylate.

6. The thermally conductive silicone material according to claim 1, characterized in that: The DGEBA epoxy value is 0.51-0.54, and the CNT is a single-layer carbon nanotube.

7. A method for preparing a thermally conductive silicone material according to any one of claims 1 to 6, characterized in that: The specific steps include: Step 1: Weigh GO and dissolve it in purified water to obtain a GO solution, weigh CNT and dissolve it in DMF to obtain a CNT solution, mix the GO solution and the CNT solution to obtain a mixed solution, weigh a dispersant and add it to the mixed solution, and perform ultrasonic dispersion to obtain a filler matrix solution; Step 2: Weigh the self-healing epoxy resin and silicone, mix, heat, and stir, then weigh the curing agent and add them, and stir to obtain a uniform and viscous mixture; Step 3: slowly adding the filler matrix solution obtained in step 1 to the mixture obtained in step 2, heating, stirring and mixing, to obtain a silica gel composite matrix; Step 4: Degas and solidify the silica gel composite matrix obtained in step 3 to obtain a thermally conductive silica gel material.

8. The method for preparing a thermally conductive silicone material according to claim 7, characterized in that: In step 1, the mass volume ratio of GO and purified water is 1 g: 5 mL, and the mass volume ratio of CNT and DMF is 1 g: 3 mL; In step 2 and step 3, the stirring process uses a high shear stirrer; In step 4, the curing conditions are 110° C. / 1 h+150° C. / 2 h, and the curing is carried out in an oven.

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