Low-thermal-resistance phase change heat conduction material and preparation method thereof

Abstract

The invention relates to a low-thermal-resistance phase change heat conduction material and a preparation method thereof, and belongs to the technical field of thermal interface materials. The phase-change-resistant heat conduction material comprises the following components in percentage by weight: 22 to 30 percent of porous BN-paraffin phase change agent, 8.5 to 10.2 percent of nano aluminum nitride, 3.5 to 4.1 percent of reactive diluent and the balance of room-temperature cured silicone rubber, according to the porous BN-paraffin phase change agent, porous BN serves as a carrier, phase change paraffin is packaged in pores, and compared with the prior art, the porous BN-paraffin phase change agent has the advantages that the pore wall of the packaged BN serves as a thermal bridge, the contact probability between the phase change agents is increased, rapid diffusion of heat in a composite material is promoted, phase change latent heat of the paraffin is fully released and conducted, and the phase change performance of the phase change agent is improved. Not only is the problem of paraffin leakage solved, but also the thermal resistance is obviously reduced.

Description

Technical Field

[0001] This invention belongs to the field of thermal interface materials technology, specifically, it relates to a low thermal resistance phase change thermal conductive material and its preparation method. Background Technology

[0002] Phase change materials (PCMs) are substances that can undergo phase transitions (such as solid-liquid, liquid-gas, or solid-solid phase transitions) and absorb or release a large amount of latent heat while maintaining a constant temperature. This phase transition process makes PCMs of significant value in the field of thermal management, especially as heat transfer media, effectively improving the thermal conductivity of composite materials. The mechanism is that when the ambient temperature reaches the phase transition point, the PCM absorbs latent heat to transition from a solid to a liquid state (or vice versa), thereby buffering temperature fluctuations and utilizing latent heat transfer to achieve efficient heat storage and release. This characteristic has led to widespread interest in PCMs in fields such as electronic heat dissipation, power battery thermal management, building energy conservation, and aerospace.

[0003] In thermally conductive composite materials, silicone rubber is often used as the matrix material due to its excellent flexibility, electrical insulation, chemical stability, and ease of processing. Combining phase change materials (PCMs) with silicone rubber can form a good thermally conductive system: silicone rubber provides structural support and interfacial bonding, while the PCM enhances the overall thermal buffering capacity through its latent heat of phase change, thereby maintaining the thermal stability of the device at high temperatures. For example, in the heat dissipation of electronic devices, this composite material can absorb the instantaneous heat generated by the chip, preventing localized overheating and extending the device's lifespan. However, PCMs in silicone rubber blends have a common drawback: due to the elastic network structure of silicone rubber, PCMs (especially liquid PCMs) are prone to displacement, leakage, or phase separation under long-term use or temperature cycling, leading to unstable thermal conductivity or even failure.

[0004] Paraffin wax, as a commonly used organic phase change material, has advantages such as stable physicochemical properties, high latent heat of phase change, wide phase change temperature range, non-toxicity, and low cost, and is therefore widely used in thermally conductive composite materials. However, the solid-liquid phase change characteristics of paraffin wax make it more prone to leakage in silicone rubber matrices. Especially under high temperature or mechanical stress, the migration of paraffin wax can damage the integrity of the composite material and reduce the reliability of thermal conductivity.

[0005] To address the issue of paraffin leakage, existing technologies primarily employ microencapsulation, which involves encapsulating paraffin within a polymer or inorganic shell using physical or chemical methods to restrict its flow. While microencapsulation effectively reduces paraffin leakage, it introduces a series of new problems: First, the shell of the microcapsule is typically composed of a low thermal conductivity material (such as polymers), with a thermal conductivity far lower than that of the paraffin itself, resulting in heat blockage at the shell and a significant increase in thermal resistance. Second, poor interfacial compatibility between the microcapsule and the silicone rubber matrix, as well as deteriorated heat transfer between microcapsules, easily leads to the formation of thermal barriers, further weakening heat transfer efficiency. Furthermore, achieving sufficient phase change effect requires the addition of a large number of microcapsules, which sacrifices the mechanical properties of silicone rubber and may induce interfacial defects, limiting the practical application of phase change thermal conductive materials. Therefore, developing a low thermal resistance, high stability phase change thermal conductive material has become an urgent industry need. Summary of the Invention

[0006] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a low thermal resistance phase change thermal conductive material and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A low thermal resistance phase change thermal conductive material, specifically composed of: 22-30 wt% porous BN-paraffin phase change agent, 8.5-10.2 wt% nano-aluminum nitride, and 3.5-4.1 wt% reactive diluent, with the balance being room temperature curing silicone rubber.

[0009] The porous BN-paraffin phase change agent is prepared by the following method:

[0010] Step A1: Sodium dodecyl sulfate and an aqueous ethanol solution are mixed, then melamine and boric acid are added and mixed well. The mixture is heated to 70-80℃ and refluxed for 4.5-6 hours. After cooling, filtration, washing, and drying to constant weight, the precursor is obtained.

[0011] Furthermore, the ratio of melamine, boric acid, sodium dodecyl sulfate, and ethanol aqueous solution is 0.1 mol: 0.13-0.15 mol: 0.6-0.8 g: 270-320 mL, and melamine and boric acid react to form a complex precursor.

[0012] Step A2: Dry grind and disperse the precursor and ammonium sulfate, then cold press the powder into sheets, then calcine under pressure in a nitrogen atmosphere, cool in the furnace and grind to obtain porous BN.

[0013] Furthermore, the mass ratio of the precursor to ammonium sulfate is 1:0.18-0.23. Under this ratio, the resulting porous BN has relatively moderate porosity and strength, and uniform pores, which is beneficial for paraffin injection and encapsulation.

[0014] Preferably, the pressure of the cold-pressed sheet is 25-30 MPa and the thickness is 8-12 mm. Under this process, the powder has good density after cold pressing, and at the same time, it meets the requirements of ammonium sulfate decomposition and pore formation, resulting in uniform pores.

[0015] Preferably, the pressure calcination adopts a two-stage continuous process: the first stage temperature is 530-550℃, the pressure is 1.5-2MPa, and the calcination time is 2-2.5h; the second stage temperature is 1420-1480℃, the pressure is 3.5-4MPa, and the calcination time is 1.8-2.5h. The two-stage calcination combined with the cold pressing process ensures that the pore walls of the prepared porous BN have good compactness, and at the same time, it is conducive to the formation of stable and uniform pores.

[0016] Step A3: Mix porous BN and paraffin wax, reduce pressure to below 50 Pa and heat until the paraffin wax melts. After depressurization, add octadecyl diethanolamine aqueous solution, sonicate and stir for 2-3 hours. After filtration, dry to constant weight to obtain the pre-encapsulated matrix.

[0017] Furthermore, the ratio of porous BN, paraffin, and octadecyl diethanolamine aqueous solution is 10g:3.6-4.4g:80-110mL. The paraffin melts and is adsorbed onto the surface of the porous BN. During the decompression process, it is carried into the pores. In an aqueous environment, the alkyl chains of octadecyl diethanolamine are embedded in the paraffin due to compatibility differences, forming a hydroxyl enrichment layer on the injected paraffin surface.

[0018] Step A4: Mix the pre-encapsulated matrix, triethylamine and anhydrous toluene, purge with dry nitrogen, slowly add vinyltrichlorosilane under ultrasonic oscillation, stir and react for 3-4 hours, finally filter and wash with ethanol and water in sequence, and dry to obtain porous BN-paraffin phase change agent.

[0019] Furthermore, the ratio of the pre-encapsulated matrix, vinyltrichlorosilane, triethylamine, and anhydrous toluene is 10g:0.5-0.7mL:1-1.5mL:60-70mL. The highly active vinyltrichlorosilane reacts with the enriched hydroxyl groups on the surface of the paraffin in the pre-encapsulated matrix to cross-link and encapsulate the internal paraffin.

[0020] A method for preparing a low thermal resistance phase change thermal conductive material is as follows: room temperature curing silicone rubber and an active diluent are mixed and diluted in a dry nitrogen environment, and then porous BN-paraffin phase change agent and nano-aluminum nitride are added sequentially and mixed evenly to obtain a low thermal resistance phase change thermal conductive material.

[0021] The beneficial effects of this invention are:

[0022] This invention achieves a balance between low thermal resistance and high stability by designing a porous BN-paraffin phase change agent and its composite structure in silicone rubber. The porous BN, acting as a carrier, provides a stable encapsulation space for the paraffin through its three-dimensional interconnected channels, and also utilizes the high thermal conductivity of BN to construct efficient heat transfer channels. During encapsulation, the synergistic effect of octadecyl diethanolamine and vinyltrichlorosilane results in a dense siloxane encapsulation layer on the paraffin surface. This layer exhibits good chemical compatibility with the silicone rubber matrix, thus preventing the phase change material from shifting or leaking during temperature cycling. Simultaneously, the BN pore walls extending into the silicone rubber act as "thermal bridges," increasing the contact probability between phase change agents and promoting rapid heat diffusion within the composite material, allowing the latent heat of phase change in the paraffin to be fully released and conducted.

[0023] Compared to existing microencapsulation technologies, this invention not only solves the paraffin leakage problem but also significantly reduces thermal resistance: the continuous thermally conductive network of BN avoids the thermal barrier effect of the polymer shell, while the flexible design of the encapsulation layer ensures the mechanical integrity of the composite material. Furthermore, the adjustable pore size of the porous BN allows for optimized paraffin loading, further balancing thermal conductivity and stability. Experimental data show that this material maintains stable thermal conductivity under long-term thermal cycling and high-temperature aging, making it suitable for heat dissipation management of high-power electronic devices. In summary, this invention, through structural innovation and process optimization, overcomes the limitations of traditional phase change thermal conductive materials, providing a new pathway for the development of high-performance thermal management materials. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: Preparation of a low thermal resistance phase change thermally conductive material. The implementation method is as follows:

[0026] (1) Preparation of porous BN-paraffin phase change agent

[0027] Step A1: Sodium dodecyl sulfate was added to a 50% (v / v) aqueous ethanol solution and stirred until dissolved. Melamine and boric acid were then added and mixed thoroughly. The mixture was heated to 70°C and refluxed for 6 hours. The ratio of melamine, boric acid, sodium dodecyl sulfate, and aqueous ethanol solution was 0.1 mol: 0.13 mol: 0.6 g: 270 mL. After cooling, the mixture was filtered, and the filter cake was washed with water and dried to constant weight to obtain the precursor.

[0028] Step A2: The precursor and ammonium sulfate are mixed and added to a grinder for dry grinding and dispersion for 10 minutes. The mixed powder is then cold-pressed into 8mm sheets at 25MPa. The sheets are placed in a pressure furnace and pressure-calcined under a nitrogen atmosphere using a two-stage continuous process. The specific process is as follows: the first stage temperature is 530℃, the pressure is 1.5MPa, and the calcination time is 2.5h; the second stage temperature is 1420℃, the pressure is 3.5MPa, and the calcination time is 2.5h. The mass ratio of the precursor to ammonium sulfate is 1:0.18. After calcination, the mixture is cooled in the furnace and then ground to obtain porous BN.

[0029] Step A3: Mix porous BN and paraffin (45# paraffin was used throughout the process), reduce the pressure to below 50 Pa, heat to 55°C to melt the paraffin, then release the pressure and add an octadecyl diethanolamine aqueous solution. After ultrasonic oscillation, stir for 3 hours. The ratio of porous BN, paraffin, and octadecyl diethanolamine aqueous solution is 10 g: 3.6 g: 80 mL. The octadecyl diethanolamine aqueous solution is a saturated aqueous solution at room temperature. Finally, filter, dry the filter cake to constant weight, and obtain the pre-encapsulated matrix.

[0030] Step A4: Mix the pre-encapsulated matrix, triethylamine, and anhydrous toluene, purge with dry nitrogen, slowly add vinyltrichlorosilane under ultrasonic oscillation, and then stir the reaction for 4 hours. The ratio of the pre-encapsulated matrix, vinyltrichlorosilane, triethylamine, and anhydrous toluene is 10 g: 0.5 mL: 1 mL: 60 mL. Finally, filter and wash with ethanol and water in sequence, and dry to obtain porous BN-paraffin phase change agent.

[0031] (2) Preparation of low thermal resistance phase change thermal conductive materials

[0032] The components are measured by weight percentage as follows: porous BN-paraffin phase change agent 22wt%, prepared in this embodiment; nano aluminum nitride 10.2wt%, using YM-ALN-800N type raw material; reactive diluent 4.1wt%, using industrial grade methyltrimethoxysilane; the balance is room temperature curing silicone rubber, using K-703 type raw material.

[0033] Room temperature curing silicone rubber and reactive diluent were mixed and diluted in a dry nitrogen atmosphere, and then porous BN-paraffin phase change agent and nano aluminum nitride were added and mixed evenly to obtain a low thermal resistance phase change thermal conductive material.

[0034] Example 2: Preparation of a low thermal resistance phase change thermally conductive material, the method of which is as follows:

[0035] (1) Preparation of porous BN-paraffin phase change agent

[0036] Step A1: Sodium dodecyl sulfate was added to a 50% (v / v) aqueous ethanol solution and stirred until dissolved. Melamine and boric acid were then added and mixed thoroughly. The mixture was heated to 80°C and refluxed for 4.5 h. The ratio of melamine, boric acid, sodium dodecyl sulfate, and aqueous ethanol solution was 0.1 mol: 0.15 mol: 0.8 g: 320 mL. After cooling, the mixture was filtered, and the filter cake was washed with water and dried to constant weight to obtain the precursor.

[0037] Step A2: The precursor and ammonium sulfate are mixed and added to a grinder for dry grinding and dispersion for 10 minutes. The mixed powder is then cold-pressed into 12mm sheets at 30MPa. The sheets are placed in a pressure furnace and pressure-calcined under a nitrogen atmosphere using a two-stage continuous process. The specific process is as follows: the first stage temperature is 550℃, the pressure is 2MPa, and the calcination time is 2h; the second stage temperature is 1480℃, the pressure is 4MPa, and the calcination time is 1.8h. The mass ratio of the precursor to ammonium sulfate is 1:0.23. After calcination, the mixture is cooled in the furnace and then ground to obtain porous BN.

[0038] Step A3: Mix porous BN and paraffin wax, reduce pressure to below 50 Pa, heat to 55°C to melt the paraffin wax, then release pressure and add octadecyl diethanolamine aqueous solution, sonicate and stir for 2 hours. The ratio of porous BN, paraffin wax and octadecyl diethanolamine aqueous solution is 10 g: 4.4 g: 110 mL. The octadecyl diethanolamine aqueous solution is a saturated aqueous solution at room temperature. Finally, filter, take the filter cake, dry to constant weight, and obtain the pre-encapsulated matrix.

[0039] Step A4: Mix the pre-encapsulated matrix, triethylamine, and anhydrous toluene, purge with dry nitrogen, slowly add vinyltrichlorosilane under ultrasonic oscillation, and then stir the reaction for 3 hours. The ratio of the pre-encapsulated matrix, vinyltrichlorosilane, triethylamine, and anhydrous toluene is 10 g: 0.7 mL: 1.5 mL: 70 mL. Finally, filter and wash with ethanol and water in sequence, and dry to obtain porous BN-paraffin phase change agent.

[0040] (2) Preparation of low thermal resistance phase change thermal conductive materials

[0041] The components are measured by weight percentage as follows: 30 wt% porous BN-paraffin phase change agent, which is self-made in this embodiment; 8.5 wt% nano aluminum nitride, using YM-ALN-800N type raw material; 3.5 wt% reactive diluent, using industrial grade methyltrimethoxysilane; the balance is room temperature curing silicone rubber, using K-703 type raw material.

[0042] Room temperature curing silicone rubber and reactive diluent were mixed and diluted in a dry nitrogen atmosphere, and then porous BN-paraffin phase change agent and nano aluminum nitride were added and mixed evenly to obtain a low thermal resistance phase change thermal conductive material.

[0043] Example 3: Preparation of a low thermal resistance phase change thermally conductive material, the method of which is as follows:

[0044] (1) Preparation of porous BN-paraffin phase change agent

[0045] Step A1: Sodium dodecyl sulfate was added to a 50% (v / v) aqueous ethanol solution and stirred until dissolved. Melamine and boric acid were then added and mixed thoroughly. The mixture was heated to 75°C and refluxed for 5.5 h. The ratio of melamine, boric acid, sodium dodecyl sulfate, and aqueous ethanol solution was 0.1 mol: 0.14 mol: 0.7 g: 300 mL. After cooling, the mixture was filtered, and the filter cake was washed with water and dried to constant weight to obtain the precursor.

[0046] Step A2: The precursor and ammonium sulfate are mixed and added to a grinder for dry grinding and dispersion for 10 minutes. The mixed powder is then cold-pressed into 10mm sheets at 27MPa. The sheets are placed in a pressure furnace and pressure-calcined under a nitrogen atmosphere using a two-stage continuous process. The specific process is as follows: the first stage temperature is 550℃, the pressure is 1.8MPa, and the calcination time is 2.2h; the second stage temperature is 1450℃, the pressure is 3.5MPa, and the calcination time is 2h. The mass ratio of the precursor to ammonium sulfate is 1:0.21. After calcination, the mixture is cooled in the furnace and then ground to obtain porous BN.

[0047] Step A3: Mix porous BN and paraffin wax, reduce pressure to below 50 Pa, heat to 55°C to melt the paraffin wax, then release pressure and add octadecyl diethanolamine aqueous solution. After ultrasonic vibration, stir for 2.5 h. The ratio of porous BN, paraffin wax and octadecyl diethanolamine aqueous solution is 10 g: 3.9 g: 100 mL. The octadecyl diethanolamine aqueous solution is a saturated aqueous solution at room temperature. Finally, filter, take the filter cake, dry to constant weight, and obtain the pre-encapsulated matrix.

[0048] Step A4: Mix the pre-encapsulated matrix, triethylamine, and anhydrous toluene, purge with dry nitrogen, slowly add vinyltrichlorosilane under ultrasonic oscillation, and then stir the reaction for 3.5 h. The ratio of the pre-encapsulated matrix, vinyltrichlorosilane, triethylamine, and anhydrous toluene is 10 g: 0.6 mL: 1.2 mL: 65 mL. Finally, filter and wash with ethanol and water in sequence, and dry to obtain porous BN-paraffin phase change agent.

[0049] (2) Preparation of low thermal resistance phase change thermal conductive materials

[0050] The components are measured by weight percentage as follows: porous BN-paraffin phase change agent 25wt%, prepared in this embodiment; nano aluminum nitride 9.2wt%, using YM-ALN-800N type raw material; reactive diluent 3.9wt%, using industrial grade methyltrimethoxysilane; the balance is room temperature curing silicone rubber, using K-703 type raw material.

[0051] Room temperature curing silicone rubber and reactive diluent were mixed and diluted in a dry nitrogen atmosphere, and then porous BN-paraffin phase change agent and nano aluminum nitride were added and mixed evenly to obtain a low thermal resistance phase change thermal conductive material.

[0052] Example 4: Preparation of a low thermal resistance phase change thermally conductive material, the method of which is as follows:

[0053] (1) Preparation of porous BN-paraffin phase change agent

[0054] Step A1: Sodium dodecyl sulfate was added to a 50% (v / v) aqueous ethanol solution and stirred until dissolved. Melamine and boric acid were then added and mixed thoroughly. The mixture was heated to 75°C and refluxed for 5 hours. The ratio of melamine, boric acid, sodium dodecyl sulfate, and aqueous ethanol solution was 0.1 mol: 0.15 mol: 0.7 g: 300 mL. After cooling, the mixture was filtered, and the filter cake was washed with water and dried to constant weight to obtain the precursor.

[0055] Step A2: The precursor and ammonium sulfate are mixed and added to a grinder for dry grinding and dispersion for 10 minutes. The mixed powder is then cold-pressed into 10mm sheets at 28MPa. The sheets are placed in a pressure furnace and pressure-calcined under a nitrogen atmosphere using a two-stage continuous process. The specific process is as follows: the first stage temperature is 550℃, the pressure is 1.7MPa, and the calcination time is 2.5h; the second stage temperature is 1450℃, the pressure is 4MPa, and the calcination time is 2.2h. The mass ratio of the precursor to ammonium sulfate is 1:0.2. After calcination, the mixture is cooled in the furnace and then ground to obtain porous BN.

[0056] Step A3: Mix porous BN and paraffin wax, reduce pressure to below 50 Pa, heat to 55°C to melt the paraffin wax, then release pressure and add octadecyl diethanolamine aqueous solution. After ultrasonic vibration, stir for 2.8 h. The ratio of porous BN, paraffin wax and octadecyl diethanolamine aqueous solution is 10 g: 4.2 g: 110 mL. The octadecyl diethanolamine aqueous solution is a saturated aqueous solution at room temperature. Finally, filter, take the filter cake, dry to constant weight, and obtain the pre-encapsulated matrix.

[0057] Step A4: Mix the pre-encapsulated matrix, triethylamine, and anhydrous toluene, purge with dry nitrogen, slowly add vinyltrichlorosilane under ultrasonic oscillation, and then stir the reaction for 4 hours. The ratio of the pre-encapsulated matrix, vinyltrichlorosilane, triethylamine, and anhydrous toluene is 10 g: 0.6 mL: 1 mL: 65 mL. Finally, filter and wash with ethanol and water in sequence, and dry to obtain porous BN-paraffin phase change agent.

[0058] (2) Preparation of low thermal resistance phase change thermal conductive materials

[0059] The components are measured by weight percentage as follows: porous BN-paraffin phase change agent 26wt%, prepared in this embodiment; nano aluminum nitride 9.5wt%, using YM-ALN-800N type raw material; reactive diluent 3.8wt%, using industrial grade methyltrimethoxysilane; the balance is room temperature curing silicone rubber, using K-703 type raw material.

[0060] Room temperature curing silicone rubber and reactive diluent were mixed and diluted in a dry nitrogen atmosphere, and then porous BN-paraffin phase change agent and nano aluminum nitride were added and mixed evenly to obtain a low thermal resistance phase change thermal conductive material.

[0061] Comparative Example 1, following the implementation method of Example 4, except that the porous BN-paraffin phase change agent was replaced with 18wt% porous BN and 8wt% paraffin, and the rest of the implementation method was exactly the same.

[0062] Comparative Example 2, following the implementation method of Example 4, replaced the porous BN-paraffin phase change agent with an equal amount of commercially available PCM-BM-44 paraffin-based microcapsules, with the remaining implementation methods being exactly the same.

[0063] The phase change thermal conductive material prepared above was injected into a mold, baked and shaped at 60℃ for 2h, and then allowed to stand naturally for 24h to cure, thus producing a sample with a specification of Φ25×2mm.

[0064] Thermal conductivity test: According to ASTM D5470-17 standard, the maximum thermal conductivity K of the sample was tested in 1℃ increments within the range of 40-55℃. max and its temperature T max ;

[0065] Thermal cycling stability test: The sample is placed in a high and low temperature test chamber and cycled 1000 times at 20-150℃. Then, the thermal conductivity K1 after thermal cycling is tested at the temperature of the previous maximum thermal conductivity.

[0066] Long-term heat resistance stability test: The sample was placed in an oven and dried at 125°C for 168 hours. Then, the thermal conductivity K2 after thermal aging was tested at the temperature of the previous maximum thermal conductivity.

[0067] The specific test results are shown in Table 1:

[0068] Table 1

[0069] <![CDATA[K max (W / (m·K))]]> <![CDATA[T max (℃)]]> <![CDATA[K1(W / (m·K))]]> <![CDATA[K2(W / (m·K))]]> Example 1 2.861 45 2.781 2.495 Example 2 3.712 50 3.538 3.363 Example 3 3.155 46 3.041 2.824 Example 4 3.509 48 3.397 3.204 Comparative Example 1 2.285 42 1.611 1.200 Comparative Example 2 1.934 46 1.795 1.534

[0070] As can be seen from the comparison of test data in Table 1, the phase change thermal conductive material prepared in the example has a high thermal conductivity. Compared with the microcapsule paraffin phase change material used in the existing Comparative Example 2, it has a lower thermal resistance. Moreover, under simulated actual thermal cycle heat dissipation and continuous high load high temperature heat dissipation conditions, the thermal conductivity of the example changes very little, and it has excellent stability.

[0071] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A low thermal resistance phase change thermally conductive material, characterized in that, The specific components are: 22-30 wt% porous BN-paraffin phase change agent, 8.5-10.2 wt% nano aluminum nitride, and 3.5-4.1 wt% reactive diluent, with the balance being room temperature curing silicone rubber; The porous BN-paraffin phase change agent is prepared by the following method: Step A1: Sodium dodecyl sulfate and an aqueous ethanol solution are mixed, then melamine and boric acid are added and mixed well. The mixture is heated to 70-80℃ and refluxed for 4.5-6 hours. After cooling, filtration, washing, and drying to constant weight, the precursor is obtained. Step A2: After dispersing the precursor and ammonium sulfate, the mixture is cold-pressed into sheets, then calcined under pressure in a nitrogen atmosphere, cooled in the furnace, and then ground to obtain porous BN. Step A3: Mix porous BN and paraffin, reduce pressure and heat to melt, release pressure and add octadecyl diethanolamine aqueous solution, sonicate and stir for 2-3 hours, filter and dry to constant weight to obtain pre-encapsulated matrix; Step A4: Mix the pre-encapsulated matrix, triethylamine and anhydrous toluene, purge with dry nitrogen, slowly add vinyltrichlorosilane under ultrasonic oscillation, stir and react for 3-4 hours, finally filter and wash with ethanol and water in sequence, and dry to obtain porous BN-paraffin phase change agent.

2. The low thermal resistance phase change thermally conductive material according to claim 1, characterized in that, The ratio of melamine, boric acid, sodium dodecyl sulfate, and ethanol aqueous solution is 0.1 mol: 0.13-0.15 mol: 0.6-0.8 g: 270-320 mL.

3. The low thermal resistance phase change thermally conductive material according to claim 1, characterized in that, The mass ratio of the precursor to ammonium sulfate is 1:0.18-0.

23.

4. The low thermal resistance phase change thermally conductive material according to claim 3, characterized in that, The pressure of the cold-pressed sheet is 25-30MPa, and the thickness is 8-12mm.

5. The low thermal resistance phase change thermally conductive material according to claim 4, characterized in that, The pressure roasting adopts a two-stage continuous process: the first stage temperature is 530-550℃, the pressure is 1.5-2MPa, and the roasting time is 2-2.5h; the second stage temperature is 1420-1480℃, the pressure is 3.5-4MPa, and the roasting time is 1.8-2.5h.

6. The low thermal resistance phase change thermally conductive material according to claim 5, characterized in that, The ratio of porous BN, paraffin and octadecyl diethanolamine aqueous solution is 10g: 3.6-4.4g: 80-110mL.

7. The low thermal resistance phase change thermally conductive material according to claim 6, characterized in that, The ratio of the pre-encapsulated matrix, vinyltrichlorosilane, triethylamine and anhydrous toluene is 10g:0.5-0.7mL:1-1.5mL:60-70mL.

8. A method for preparing a low thermal resistance phase change thermally conductive material according to any one of claims 1-7, characterized in that, Specifically, room temperature curing silicone rubber and reactive diluent are mixed in a dry nitrogen atmosphere, and then porous BN-paraffin phase change agent and nano-aluminum nitride are added sequentially and mixed evenly to obtain a low thermal resistance phase change thermal conductive material.