Heat conduction material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of heat-conducting materials, and discloses a heat-conducting material and a preparation method and application thereof, the heat-conducting material comprises the following raw materials: a heat-conducting filler, a surface modifier, a shape memory polymer and a paraffin coated SiO2 phase change microcapsule. The compression ratio of the shape memory polymer and the temperature are in a nonlinear relationship (the threshold value is 80-100 DEG C and the compression ratio is 15-30%), the compression ratio of the gasket is increased and the interface thermal resistance is reduced after the temperature exceeds the threshold value (80-100 DEG C), the phase change microcapsule is doped, and the phase change temperature (50-70 DEG C) of the paraffin is lower than the trigger temperature (80-100 DEG C) of the memory polymer, so that dual-stage thermal buffering is formed; heat is absorbed in the temperature rising period, the heating rate is delayed, the thermal shock risk is reduced, and microcosmic gaps are filled in a liquid state at high temperature to reduce contact thermal resistance; and meanwhile, the heat-conducting filler is compounded with the shape memory polymer matrix, so that the synergistic interaction of static heat conduction and dynamic compression is realized.

Description

Technical Field

[0001] This invention relates to the field of thermal conductive materials technology, specifically to a thermal conductive material, its preparation method, and its application. Background Technology

[0002] With the rapid development of cutting-edge technologies such as artificial intelligence, the performance of electronic devices is constantly improving, and their demand for thermal management is also increasing. However, due to the existence of tiny gaps between electronic components and heat dissipation devices, direct contact often results in ineffective heat dissipation. To solve this problem, thermal interface materials have emerged. They can effectively fill these gaps, creating a good heat conduction channel between the heat sink and electronic components, thereby significantly improving heat dissipation efficiency and enhancing the performance and lifespan of electronic components. In addition to high thermal conductivity, high-performance thermal interface materials typically also require good electrical insulation and certain mechanical properties.

[0003] Currently, the most widely used thermal interface materials on the market mainly include thermal pads, thermal grease, thermal gel, and thermal potting compounds. Among them, thermal pads, due to their advantages of low cost and ease of industrial production, have been widely used in many fields, providing strong support for the stable operation of electronic devices.

[0004] Hexagonal boron nitride (h-BN), as a ceramic material, has a molecular structure similar to graphite. This similarity gives both materials many of the same properties, such as excellent mechanical strength, high thermal conductivity, spatial anisotropy, and excellent lubricity. In addition, h-BN also possesses excellent electrical insulation properties. Therefore, the fabrication of high thermal conductivity pads by combining h-BN with polymer matrices has broad application prospects. However, traditional pad materials lack temperature self-sensing and self-adaptive capabilities, resulting in a contradiction between increased thermal resistance at high temperatures and insufficient adhesion at low temperatures. Rapid heating leading to long-term thermal cycling (such as sudden loads in 5G base stations) or mechanical vibration can cause the pad to separate from the device surface, resulting in increased contact thermal resistance and a sharp drop in heat dissipation efficiency. This causes electronic components to exceed critical temperatures under high load conditions, accelerating aging and ultimately leading to thermal failure.

[0005] Therefore, how to adjust and optimize the formulation and preparation method of thermally conductive materials to obtain thermally conductive materials with temperature self-regulation is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the present invention provides a thermally conductive material with temperature self-regulation.

[0007] The present invention also provides a method for preparing the above-mentioned thermally conductive material.

[0008] In a first aspect, the present invention provides a thermally conductive material, the thermally conductive material comprising a thermally conductive filler, a surface modifier, a shape memory polymer, and paraffin@SiO2 phase change microcapsules;

[0009] The paraffin@SiO2 phase change microcapsules account for 6%-15% of the total mass of the thermally conductive material;

[0010] The shape memory polymer accounts for 24%-35% of the total mass of the thermally conductive material.

[0011] In some optional embodiments, the paraffin@SiO2 phase change microcapsules account for 6%-9% of the total mass of the thermally conductive material.

[0012] In some optional embodiments, the shape memory polymer accounts for 28%-29% of the total mass of the thermally conductive material.

[0013] In some optional embodiments, the surface modifier accounts for 0.4%-1.5% of the total mass of the thermally conductive material.

[0014] In some optional embodiments, the surface modifier comprises a silane coupling agent, which includes at least one of γ-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0015] In some optional embodiments, the thermally conductive filler includes at least one of hexagonal boron nitride, spherical alumina, spherical aluminum nitride, and near-spherical zinc oxide.

[0016] In some optional embodiments, the particle size of the thermally conductive filler is 5µm-30µm.

[0017] In some optional embodiments, the shape memory polymer includes at least one of shape memory polyurethane, shape memory epoxy resin, shape memory polyester, and shape memory polyolefin.

[0018] In some optional embodiments, the shape memory polyolefin includes at least one of shape memory polyethylene, shape memory cyclic olefin copolymer, and shape memory polystyrene.

[0019] Secondly, the present invention provides a method for preparing the above-mentioned thermally conductive material, comprising the following steps:

[0020] (1) Mix the thermally conductive filler, surface modifier, and shape memory polymer to obtain a mixture;

[0021] (2) The mixture and paraffin@SiO2 phase change microcapsules are stirred and solidified to obtain the following:

[0022] The curing step includes a first curing and a second curing, wherein the temperature of the first curing is 60℃-80℃ and the temperature of the second curing is 120℃-140℃.

[0023] In some alternative embodiments, the first curing time is 30 min to 60 min.

[0024] In some optional embodiments, the second curing time is 60 min to 120 min.

[0025] In some optional embodiments, the mixing temperature is 70°C-80°C and the time is 2h-6h.

[0026] In some optional embodiments, the stirring speed is 250 rpm to 750 rpm and the stirring time is 15 min to 60 min.

[0027] In some alternative embodiments, step (1) further includes adding a solvent, said solvent including at least one of ethanol and deionized water.

[0028] Thirdly, the present invention provides an application of the thermally conductive material prepared by the thermally conductive material described in the first aspect or the preparation method described in the second aspect as a thermal interface material.

[0029] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0030] 1. The thermally conductive material provided by this invention comprises thermally conductive fillers, surface modifiers, shape memory polymers, and paraffin@SiO2 phase change microcapsules. The compressibility of the shape memory polymer exhibits a non-linear relationship with temperature (threshold 80℃-100℃ and compressibility 15%-30%). After the temperature exceeds the threshold (80℃-100℃), the material compressibility increases, reducing interfacial thermal resistance. Furthermore, the incorporation of phase change microcapsules, with the paraffin phase change temperature (50℃-70℃) lower than the shape memory polymer trigger temperature (80℃-100℃), forms a two-stage thermal buffer. During the temperature rise phase, it absorbs heat, slowing the heating rate and reducing the risk of thermal shock. At high temperatures, it liquid-likely fills microscopic gaps, reducing contact thermal resistance. Simultaneously, the composite of the thermally conductive filler and the shape memory polymer matrix achieves a synergistic effect of static thermal conductivity and dynamic compression.

[0031] 2. The preparation method of the thermally conductive material provided by the present invention includes the following steps: mixing thermally conductive filler, surface modifier, and shape memory polymer to obtain a mixture; stirring, calendering, and curing the mixture with paraffin@SiO2 phase change microcapsules to obtain the final product; the curing step includes a first curing and a second curing, the first curing temperature being 60℃-80℃ and the second curing temperature being 120℃-140℃; the present invention adopts a segmented curing method. At the first curing temperature, the liquid paraffin formed by the phase change of the microcapsules has a high viscosity, and the shape memory polymer will undergo pre-crosslinking / curing at this stage, making it difficult for the liquid paraffin to penetrate into the crosslinking network of the shape memory polyurethane; at the second curing temperature, although the viscosity of the liquid paraffin decreases, it is still difficult for the liquid paraffin to penetrate into the crosslinking network of the shape memory polyurethane because the shape memory polymer has been fully crosslinked, and it tends to be adsorbed by the thermally conductive filler, which helps to reduce the contact thermal resistance between the filler and the device surface during use. Detailed Implementation

[0032] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0033] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0034] To address the problems existing in the aforementioned related technologies, according to a first aspect of the present invention, a thermally conductive material is provided, the thermally conductive material comprising a thermally conductive filler, a surface modifier, a shape memory polymer, and paraffin@SiO2 phase change microcapsules.

[0035] In some optional embodiments, the paraffin@SiO2 phase change microcapsules account for 6%-15% of the total mass of the thermally conductive material.

[0036] In some optional embodiments, the shape memory polymer accounts for 24%-35% of the total mass of the thermally conductive material.

[0037] In some optional embodiments, the paraffin@SiO2 phase change microcapsules account for 6%-9% of the total mass of the thermally conductive material.

[0038] In some optional embodiments, the shape memory polymer accounts for 28%-29% of the total mass of the thermally conductive material.

[0039] In some optional embodiments, the surface modifier accounts for 0.4%-1.5% of the total mass of the thermally conductive material.

[0040] In some optional embodiments, the surface modifier comprises a silane coupling agent, which includes at least one selected from γ-aminopropyltriethoxysilane (KH-550), N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane (KH-602), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), γ-glycidoxypropyltrimethoxysilane (KH-560), γ-methacryloyloxypropyltrimethoxysilane (KH-570), and vinyltrimethoxysilane (A-171).

[0041] In some optional embodiments, the thermally conductive filler includes at least one of hexagonal boron nitride, spherical alumina, spherical aluminum nitride, and near-spherical zinc oxide.

[0042] In some optional embodiments, the thermally conductive filler has a size of 5µm-30µm.

[0043] In some optional embodiments, the shape memory polymer includes at least one of shape memory polyurethane, shape memory epoxy resin, shape memory polyester, and shape memory polyolefin.

[0044] In some optional embodiments, the shape memory polyolefin includes at least one of shape memory polyethylene, shape memory cyclic olefin copolymer, and shape memory polystyrene.

[0045] The raw materials for the thermally conductive material include thermally conductive fillers, surface modifiers, shape memory polymers, and paraffin@SiO2 phase change microcapsules. The compressibility of the shape memory polymer exhibits a non-linear relationship with temperature (threshold 80℃-100℃ and compressibility 15%-30%). After the temperature exceeds the threshold (80℃-100℃), the material's compressibility increases, reducing interfacial thermal resistance. Furthermore, the incorporation of phase change microcapsules, with the paraffin phase change temperature (50℃-70℃) lower than the shape memory polymer trigger temperature (80℃-100℃), forms a two-stage thermal buffer. During the temperature rise phase, it absorbs heat, slowing the heating rate and reducing the risk of thermal shock. At high temperatures, it exists as a liquid, filling microscopic gaps to reduce contact thermal resistance. Simultaneously, the combination of the thermally conductive filler and the shape memory polymer matrix achieves a synergistic effect of static thermal conductivity and dynamic compression.

[0046] In a second aspect, the present invention provides a method for preparing the thermally conductive material described in the first aspect, comprising the following steps:

[0047] (1) Mix the thermally conductive filler, surface modifier, and shape memory polymer to obtain a mixture;

[0048] (2) The mixture and paraffin@SiO2 phase change microcapsules are stirred and solidified to obtain the following:

[0049] The curing step includes a first curing and a second curing, wherein the temperature of the first curing is 60℃-80℃ and the temperature of the second curing is 120℃-140℃.

[0050] Understandably, the first curing and the second curing are carried out sequentially.

[0051] In some alternative embodiments, the first curing time is 30 min to 60 min.

[0052] In some optional embodiments, the second curing time is 60 min to 120 min.

[0053] In some optional embodiments, the mixing temperature is 70°C-80°C and the time is 2h-6h.

[0054] In some optional embodiments, the stirring speed is 250 rpm to 750 rpm and the stirring time is 15 min to 60 min.

[0055] In some alternative embodiments, step (1) further includes adding a solvent, said solvent including at least one of ethanol and deionized water.

[0056] The method for preparing the thermally conductive material provided by the present invention controls the curing steps, including a first curing and a second curing, to ensure the resilience of the shape memory polymer.

[0057] Thirdly, the application of thermally conductive materials prepared by the thermally conductive materials described in the first aspect or by the preparation method described in the second aspect as thermal interface materials.

[0058] In some alternative embodiments, the thermal interface material includes a thermally conductive material.

[0059] In this invention, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane was purchased from Nanjing Nengde New Material Technology Co., Ltd., model number KH-602; N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was purchased from Nanjing Nengde New Material Technology Co., Ltd., model number KH-792.

[0060] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0061] Preparation Example 1

[0062] This preparation example provides a method for preparing paraffin@SiO2 phase change microcapsules, including the following steps:

[0063] 20g of paraffin powder, 5g of cetyltrimethylammonium bromide, 250g of deionized water and 200g of anhydrous ethanol were added to a 500mL beaker. The mixture was heated to 75℃ in a water bath and dispersed at 1500rpm for 30min using a high-speed disperser. After dispersion, the speed was maintained and 15g of tetraethyl orthosilicate was slowly added dropwise to the beaker. After the addition was complete, the mixture was dispersed at high speed for 5min. Then, it was transferred to a three-necked flask and mechanically stirred at 300rpm in a 65℃ water bath. 10mL of ammonia water was added dropwise and stirred continuously for 3h. After stirring was completed, the mixture was allowed to stand for 3h, filtered, washed and dried to obtain paraffin@SiO2 phase change microcapsules.

[0064] Example 1

[0065] This embodiment provides a method for preparing a thermally conductive pad, including the following steps:

[0066] (1) Take 20g of 30μm hexagonal boron nitride powder, 6g of 5μm spherical aluminum nitride powder, 100g of anhydrous ethanol, and 0.2g of KH-550. Stir for 2 hours at 80℃ and 800rpm using a high-speed disperser. After filtration and drying, mix with 11.2g of shape memory polyurethane to obtain a mixture.

[0067] (2) The mixture was mixed with 2.4g of paraffin@SiO2 phase change microcapsules prepared in Preparation Example 1 and stirred at 500rpm for 30min to obtain a pad paste. The pad paste was calendered to a thickness of 2mm using a calender and cured at 80℃ for 30min to complete the initial crosslinking of shape memory polymer (SMP). The temperature was then raised to 120℃ and cured for 1h to obtain a thermally conductive pad with stable compression resilience. Among them, shape memory polyurethane accounted for 28.2% of the total mass of the thermally conductive pad, paraffin@SiO2 phase change microcapsules accounted for 6% of the total mass of the thermally conductive pad, and silane coupling agent accounted for 0.50% of the total mass of the thermally conductive pad.

[0068] Example 2

[0069] This embodiment provides a method for preparing a thermally conductive pad, including the following steps:

[0070] (1) Take 18g of 30μm hexagonal boron nitride powder, 8g of 5μm spherical aluminum nitride powder, 100g of anhydrous ethanol, and 0.2g of KH-550. Stir for 2 hours at 80℃ and 800rpm using a high-speed disperser. Filter, dry, and mix evenly with 12g of shape memory polyurethane to obtain a mixture.

[0071] (2) The mixture was mixed with 3.6g of the paraffin@SiO2 phase change microcapsules prepared in Example 1 and stirred at 500rpm for 30min to obtain a pad paste. The pad paste was calendered to a thickness of 2mm using a calender and cured at 80℃ for 30min to complete the initial crosslinking of SMP. The temperature was then raised to 120℃ and cured for 1h to form a thermally conductive pad with stable compression and resilience. Among them, shape memory polyurethane accounted for 28.7% of the total mass of the thermally conductive pad, paraffin@SiO2 phase change microcapsules accounted for 8.6% of the total mass of the thermally conductive pad, and silane coupling agent accounted for 0.48% of the total mass of the thermally conductive pad.

[0072] Example 3

[0073] This embodiment provides a method for preparing a thermally conductive pad, including the following steps:

[0074] (1) Take 18g of 20μm spherical aluminum nitride powder, 6g of 25μm spherical alumina powder, 100g of anhydrous ethanol and 0.4g of KH-602, stir for 6h at 70℃ and 800rpm using a high-speed disperser, filter and wash with water, and mix evenly with 12g of shape memory polyurethane matrix to obtain a mixture.

[0075] (2) The mixture was mixed with 4g of paraffin@SiO2 phase change microcapsules prepared in Example 1 and stirred at 250rpm for 60min to obtain a pad paste. The pad paste was calendered to a thickness of 2mm using a calender and cured at 70℃ for 45min to complete the initial crosslinking of SMP. The temperature was then raised to 140℃ and cured for 120min to form a thermally conductive pad with stable compression and resilience. Among them, shape memory polyurethane accounted for 29.7% of the total mass of the thermally conductive pad, paraffin@SiO2 phase change microcapsules accounted for 9.9% of the total mass of the thermally conductive pad, and silane coupling agent accounted for 0.99% of the total mass of the thermally conductive pad.

[0076] Example 4

[0077] This embodiment provides a method for preparing a thermally conductive pad, including the following steps:

[0078] (1) Take 18g of 20μm spherical aluminum nitride powder, 6g of 25μm spherical alumina powder, 100g of anhydrous ethanol and 0.3g of A-171, stir for 6h at 70℃ and 800rpm using a high-speed disperser, filter and wash with water, and mix evenly with 10g of shape memory cyclic olefin copolymer matrix to obtain a mixture.

[0079] (2) The mixture was mixed with 6g of paraffin@SiO2 phase change microcapsules prepared in Example 1 and stirred at 250rpm for 60min to obtain a pad paste. The pad paste was calendered to a thickness of 2mm using a calender and cured at 70℃ for 45min to complete the initial crosslinking of SMP. The temperature was then raised to 140℃ and cured for 120min to form a thermally conductive pad with stable compression and resilience. Among them, shape memory polyurethane accounted for 24.8% of the total mass of the thermally conductive pad, paraffin@SiO2 phase change microcapsules accounted for 14.9% of the total mass of the thermally conductive pad, and silane coupling agent accounted for 0.74% of the total mass of the thermally conductive pad.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a thermally conductive pad, which is basically the same as the steps in Example 1, except that the paraffin@SiO2 phase change microcapsules are replaced with spherical silicon dioxide.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a thermally conductive pad, which is basically the same as the steps in Example 2, except that the addition of KH-550 is omitted.

[0084] Comparative Example 3

[0085] This comparative example provides a method for preparing a thermally conductive pad, which is basically the same as the steps in Example 1, except that shape memory polyurethane is replaced with high elasticity polyurethane.

[0086] Comparative Example 4

[0087] This comparative example provides a method for preparing a thermally conductive pad, which is basically the same as the steps in Example 1, except that the mass of the shape memory polyurethane is 7.15g, accounting for 20% of the total mass of the thermally conductive pad.

[0088] Comparative Example 5

[0089] This comparative example provides a method for preparing a thermally conductive pad, which is basically the same as the steps in Example 1, except that the mass of the shape memory polyurethane is 19.1g, accounting for 40.04% of the total mass of the thermally conductive pad.

[0090] Comparative Example 6

[0091] This comparative example provides a method for preparing a thermal pad, which is basically the same as the steps in Example 1, except that the mass of the paraffin@SiO2 phase change microcapsules is 2g, accounting for 5.07% of the total mass of the thermal pad.

[0092] Comparative Example 7

[0093] This comparative example provides a method for preparing a thermal pad, which is basically the same as the steps in Example 1, except that the mass of the paraffin@SiO2 phase change microcapsules is 9.4g, accounting for 20.09% of the total mass of the thermal pad.

[0094] Comparative Example 8

[0095] This comparative example provides a method for preparing a thermally conductive pad, which is basically the same as the steps in Example 1, except that the curing temperature is 120°C and the curing time is 90 min.

[0096] Experimental Example 1

[0097] The thermally conductive pads prepared in Examples 1-4 and Comparative Examples 1-7 were tested for thermal conductivity and contact thermal resistance at 25°C and 100°C according to ASTM-D5470. The samples were cut into 25mm×25mm×2mm pieces and, with reference to ASTM-D575, a compression ratio test was performed at 100°C with a pressure of 40psi. The results are shown in the table below.

[0098] Table 1. Performance test results of thermal pads in each embodiment and comparative example.

[0099]

[0100]

[0101] As can be seen from the table above, the thermal pads prepared in Examples 1 and 4 exhibit good thermal conductivity at both 25°C and 100°C, low contact thermal resistance at both 25°C and 100°C, and a compression ratio of 24%-30% at 100°C.

[0102] In Comparative Example 1, replacing the paraffin@SiO2 phase change microcapsules with spherical silica significantly reduced the high-temperature compressibility, increased the contact thermal resistance at 100℃, and decreased the thermal conductivity. This is because spherical silica lacks phase change characteristics and cannot undergo a phase change at high temperatures. In contrast, the paraffin@SiO2 phase change microcapsules undergo a phase change from solid to liquid, which allows them to automatically spread and fill the microscopic gaps, thus reducing thermal resistance.

[0103] In Comparative Example 2, KH-550 was omitted, resulting in a lack of amino functional groups on the surface of the thermally conductive filler. This led to poor compatibility with shape memory polyurethane, which in turn increased the interfacial thermal resistance between the filler and the matrix, resulting in a decrease in the thermal conductivity of the sample.

[0104] Comparative Example 3 replaced shape memory polyurethane with high elasticity polyurethane. High elasticity polyurethane is prone to chain segment relaxation at high temperatures and does not have shape memory ability. Therefore, it cannot provide sufficient resilience, resulting in a decrease in compression ratio, an increase in contact thermal resistance at high temperatures, and a decrease in thermal conductivity.

[0105] In Comparative Example 4, shape memory polyurethane accounted for 20% of the total mass of the thermally conductive pad, which is relatively low. This is equivalent to increasing the proportion of thermally conductive filler in the pad, resulting in a higher thermal conductivity of the pad at low temperatures. However, at high temperatures, the relatively small amount of shape memory polyurethane cannot provide sufficient resilience, leading to a decrease in the pad's compressibility, an increase in contact thermal resistance, and a lower thermal conductivity measured at high temperatures.

[0106] In Comparative Example 5, shape memory polyurethane accounted for 40.04% of the total mass of the thermal pad, which was too high. This resulted in a decrease in the proportion of thermally conductive filler and a reduction in the thermal conductivity of the sample.

[0107] In Comparative Example 6, the paraffin@SiO2 phase change microcapsules accounted for 5.07% of the total mass of the thermal pad, which was relatively low. Therefore, there was less liquid paraffin formed by the phase change at high temperatures, which could not fully fill the micro gaps, resulting in an increase in the contact thermal resistance and a decrease in the thermal conductivity measured at high temperatures.

[0108] In Comparative Example 7, the paraffin@SiO2 phase change microcapsules accounted for 20.09% of the total mass of the thermal pad, which was relatively high. This resulted in a decrease in the filling ratio of the thermally conductive filler and a reduction in the thermal conductivity of the sample. Theoretically, at high temperatures, increasing the number of phase change microcapsules could reduce contact thermal resistance. However, after the microcapsules undergo a phase change and transform into liquid paraffin, they cannot provide elasticity within the composite material. This leads to a decrease in the overall resilience and compressibility of the thermal pad, resulting in an increase in high-temperature contact thermal resistance.

[0109] Comparative Example 8 was directly cured at 120°C for 90 minutes. At low temperatures, since the microcapsules do not undergo phase change and the shape memory polyurethane does not exhibit shape memory properties, the thermal conductivity and contact thermal resistance at low temperatures are not significantly different from those of Example 1. However, at high temperatures, the thermal conductivity decreases, the contact thermal resistance increases, and the resilience decreases. This is because the temperature is high during one-step curing, and the liquid paraffin formed by the phase change of the microcapsules penetrates into the incompletely cross-linked network structure of the shape memory polyurethane, reducing the density of the cross-linked network, which leads to a decrease in the elasticity of the shape memory polymer, a weakening of the shape memory effect, and a decrease in the compressibility of the thermal pad at high temperatures.

[0110] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A thermally conductive material, characterized in that, The thermally conductive material includes thermally conductive fillers, surface modifiers, shape memory polymers, and paraffin@SiO2 phase change microcapsules; The paraffin@SiO2 phase change microcapsules account for 6%-15% of the total mass of the thermally conductive material; The shape memory polymer accounts for 24%-35% of the total mass of the thermally conductive material.

2. The thermally conductive material according to claim 1, characterized in that, The paraffin@SiO2 phase change microcapsules account for 6%-9% of the total mass of the thermally conductive material; The shape memory polymer accounts for 28%-29% of the total mass of the thermally conductive material.

3. The thermally conductive material according to claim 1, characterized in that, The surface modifier accounts for 0.4%-1.5% of the total mass of the thermally conductive material; And / or, the surface modifier includes a silane coupling agent, which includes at least one of γ-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

4. The thermally conductive material according to claim 1, characterized in that, The thermally conductive filler includes at least one of hexagonal boron nitride, spherical alumina, spherical aluminum nitride, and near-spherical zinc oxide. And / or, the particle size of the thermally conductive filler is 5μm-30μm.

5. The thermally conductive material according to claim 1, characterized in that, The shape memory polymer includes at least one of shape memory polyurethane, shape memory epoxy resin, shape memory polyester, and shape memory polyolefin.

6. The thermally conductive material according to claim 5, characterized in that, The shape memory polyolefin includes at least one of shape memory polyethylene, shape memory cyclic olefin copolymer, and shape memory polystyrene.

7. A method for preparing the thermally conductive material according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Mix the thermally conductive filler, surface modifier, and shape memory polymer to obtain a mixture; (2) The mixture and paraffin@SiO2 phase change microcapsules are stirred and solidified to obtain the following: The curing step includes a first curing and a second curing, wherein the temperature of the first curing is 60℃-80℃ and the temperature of the second curing is 120℃-140℃.

8. The method for preparing the thermally conductive material according to claim 7, characterized in that, The first curing time is 30-60 minutes; And / or, the second curing time is 60 min to 120 min.

9. The method for preparing the thermally conductive material according to claim 7, characterized in that, The mixing temperature is 70℃-80℃, and the time is 2h-6h; And / or, the stirring speed is 250 rpm-750 rpm, and the stirring time is 15 min-60 min; And / or, step (1) further includes adding a solvent, said solvent including at least one of ethanol and deionized water.

10. The application of the thermally conductive material according to any one of claims 1-6 or the thermally conductive material prepared by the preparation method according to any one of claims 7-9 as a thermal interface material.

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