Heat-conducting pouring sealant and preparation method thereof

Abstract

The invention discloses a temperature response type heat-conducting pouring sealant and a preparation method thereof, and belongs to the technical field of electronic packaging materials. The pouring sealant is composed of vinyl silicone oil, BN, a modified PNIPAM-coated Al2O3 composite material and hydrogen-containing silicone oil, surface hydroxyl activity is enhanced by pretreating Al2O3 nanoparticles (calcining at 600-800 DEG C), and the Al2O3 nanoparticles and triethylchlorosilane modified PNIPAM form a stable Si-O-Al bond structure. The thermal conductivity is dynamically adjusted within the range of 0.35-2.78 W / (m.K) by introducing lauryl sodium sulfate as a pore-forming agent and combining with the phase change characteristic of the temperature-responsive PNIPAM: the PNIPAM shrinks at low temperature to reduce thermal conductivity and inhibit condensation, and a hydrophilic chain segment extends at high temperature to form a continuous thermal conduction network. According to the preparation process, the A / B component and the pore-forming agent are mixed step by step, so that the pouring sealant is uniformly dispersed at the viscosity of 784-823 mPa.s, and the problem that the viscosity of a traditional material is sharply increased due to filler agglomeration is solved.

Description

Technical Field

[0001] The invention relates to the technical field of thermal conductive potting adhesive, and in particular to a thermal conductive potting adhesive and a preparation method thereof. Background Art

[0002] With the rapid development of modern electronic devices, especially high-power electronics and semiconductor devices, heat dissipation has gradually become a key factor limiting equipment performance and reliability. As an important thermal management material, thermal conductive potting glue is widely used in LED lighting, power modules, automotive electronics, aerospace and other fields, and undertakes the dual functions of improving thermal conductivity and electrical insulation protection. In recent years, with the miniaturization of equipment and the increase in power density, the performance requirements of thermal conductive glue have become increasingly stringent. Traditional thermal conductive potting glue is usually composed of a silicon-based or epoxy resin matrix and a thermal conductive filler (such as alumina, graphite, carbon nanotubes, etc.). Although its thermal conductivity is high, its performance at different operating temperatures has not been dynamically optimized. In order to adapt to various working environments, the development of thermal conductive glue with temperature-responsive materials has gradually become a research hotspot for improving thermal management efficiency and system reliability.

[0003] Chinese patent (CN102337033B) discloses an addition-type high thermal conductivity organic silicon electronic potting glue and its preparation method. Vinyl polydimethylsiloxane, spherical aluminum oxide, boron nitride, and silicon carbide whiskers are added to a kneader and ground to obtain a base material; equal weight parts of component A and component B are blended evenly, and degassed under a vacuum degree of 0.06 to 0.1 MPa to obtain an addition-type high thermal conductivity organic silicon electronic potting glue. The potting glue has excellent fluidity and a thermal conductivity greater than 1.0 W·m -1 ·K -1 The cured product has good mechanical and electrical properties. The thermal conductivity of existing thermal conductive adhesives is designed to achieve high thermal conductivity, with a thermal conductivity of 1.0 W·m -1 ·K -1 , which may cause the thermal conductive adhesive to have excessive heat dissipation efficiency under certain extreme temperature conditions. For example, under low temperature conditions, the thermal conductivity of the thermal conductive adhesive may be too high and cannot effectively maintain the thermal balance inside the device, which may affect the working performance of electronic components and even cause condensation, thereby causing electrical short circuits or other physical damage. Summary of the invention

[0004] The thermal conductivity of existing thermal conductive adhesives is designed to achieve high thermal conductivity, with a thermal conductivity of 1.0 W·m -1 ·K -1, which may cause the thermal conductive adhesive to have excessive heat dissipation efficiency under certain extreme temperature conditions. For example, under low temperature conditions, the thermal conductivity of the thermal conductive adhesive may be too high and cannot effectively maintain the thermal balance inside the device, which may affect the working performance of electronic components and even cause condensation, thereby causing electrical short circuits or other physical damage.

[0005] The present application provides step S1. BN, modified PNIPAM@Al2O3 composite material and silane coupling agent are added to vinyl silicone oil, and component A is obtained by high-speed shear dispersion; step S2. The hydrogen-containing silicone oil is mixed with a platinum catalyst to obtain component B; step S3. Component A and component B are mixed in a mass ratio of 10:1, and a pore-forming agent is added to mix to obtain a thermally conductive potting compound.

[0006] It should be noted that the preparation method of the thermal conductive potting glue provided in the present application is a step-by-step operation, combining the functions of different components, and finally obtaining a composite material with excellent thermal conductivity and temperature control performance. In step S1, vinyl silicone oil is used as a matrix material, and BN and modified PNIPAM@Al2O3 composite materials are added, wherein BN is a high thermal conductivity filler, which can significantly improve the thermal conductivity of the material; the modified PNIPAM@Al2O3 composite material provides temperature control performance to adjust the thermal conductivity to achieve temperature adaptive regulation, and the modified PNIPAM@Al2O3 composite material improves the dispersibility between the filler and the matrix, reduces the aggregation and agglomeration between particles, and avoids the increase in viscosity caused by aggregation. The silane coupling agent plays a role in promoting the interface bonding between the filler and the vinyl silicone oil in this step. In step S2, the hydrogen-containing silicone oil is mixed with a platinum catalyst to form component B. The hydrogen-containing silicone oil provides a cross-linking group in the subsequent cross-linking process, and the platinum catalyst promotes the cross-linking reaction and improves the thermal stability and mechanical strength of the colloid. In step S3, component A and component B are mixed at a mass ratio of 10:1 to ensure that the two components can react effectively to form a strong cross-linked structure, and finally obtain a thermally conductive potting compound with both excellent thermal conductivity and temperature response characteristics. Sodium dodecyl sulfate, as a pore-forming agent, forms a microporous structure in the solution, which promotes the potting compound material to have good temperature control characteristics.

[0007] As a preferred technical solution for the preparation of a thermally conductive potting adhesive, the preparation steps of the modified PNIPAM@Al2O3 composite material include the following: dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 10wt% to 30wt% N-isopropylacrylamide solution, adding a catalyst, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution. After fully stirring, heating to 50-80°C to form a modified PNIPAM@Al2O3 composite material.

[0008] It should be noted that the N-isopropylacrylamide (NIPAM) monomer is first dissolved in deionized water to prepare a solution of a certain concentration, and then a catalyst is added. By heating to 50-80°C, the catalyst forms a uniform NIPAM coating layer on the surface of the Al2O3 nanoparticles, so that the formed PNIPAM@Al2O3 composite material not only has temperature control performance, but also has a dispersing effect, reducing the viscosity of the potting glue.

[0009] As a preferred technical solution for the preparation method of a thermally conductive potting adhesive, the catalyst is triethylchlorosilane, and the triethylchlorosilane accounts for 1wt% to 3wt% of the N-isopropylacrylamide.

[0010] It should be noted that the chlorosilane group (-SiCl3) of triethylchlorosilane reacts with water to generate triethoxysilane (Si-OH) containing active hydroxyl (-OH) groups, and the generated Si-OH groups further react with the hydroxyl (-OH) groups on the surface of Al2O3 particles to form a stable Si-O-Al bond. When the NIPAM monomer is added to the solution and heated, the siloxy group (Si-OH) on the surface of Al2O3 interacts with the amino group (-NH2) in the NIPAM monomer to form a stable initial polymerization site. This reaction enables the NIPAM molecules to be effectively fixed on the surface of Al2O3, providing active sites for subsequent polymerization reactions. Then, under the catalysis of triethylchlorosilane, the NIPAM monomer in the Si-O-NIPAM complex undergoes free radical polymerization with other NIPAM molecules to form PNIPAM polymer chains. This process allows the PNIPAM chain to be firmly attached to the Al2O3 surface through graft copolymerization to form a stable coating. In addition, the ethyl (-CH2CH3) group in triethylchlorosilane is hydrophobic, which plays an important role in the dispersibility of the composite material, promoting the compatibility between the filler and the matrix and avoiding the aggregation and precipitation of particles.

[0011] As a preferred technical solution of a method for preparing a thermally conductive potting adhesive, the pore-forming agent is sodium dodecyl sulfate, and the sodium dodecyl sulfate accounts for 0.1 wt % to 0.5 wt % of the N-isopropylacrylamide.

[0012] It should be noted that sodium dodecyl sulfate, as a pore-forming agent, can adjust thermal conductivity under different temperature conditions by introducing a microporous structure into the colloid. When the temperature rises, NIPAM shows temperature responsiveness and changes to a flowing state. The polymer chain becomes more flexible and the fluidity is enhanced. At this time, the micropores provide a channel for heat conduction, allowing heat to be conducted more easily in the colloid, thereby improving the thermal conductivity. When the temperature drops, NIPAM returns to a solid state, the polymer chain shrinks, and becomes denser. At this time, the microporous structure plays an isolating role, reducing the path of heat conduction, resulting in a decrease in thermal conductivity. The presence of micropores can enable the thermally conductive potting glue to maintain good thermal management performance under different environments through this temperature change adjustment mechanism, which can not only improve the thermal conductivity efficiency at high temperatures, but also reduce heat conduction at low temperatures, thereby optimizing the temperature control performance of the material.

[0013] As a preferred technical solution for the preparation method of a thermally conductive potting compound, the preparation method of the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 600°C to 800°C for 2 to 4 hours.

[0014] It should be noted that the main purpose of this high temperature treatment is to improve the surface properties of Al2O3 nanoparticles and generate Al-OH groups.

[0015] As a preferred technical solution for a method for preparing a thermally conductive potting adhesive, the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 1:1 to 3:1.

[0016] It should be noted that by reasonably adjusting this ratio, precise control of the phase change behavior of the composite material can be achieved.

[0017] As a preferred technical solution for a method for preparing a thermally conductive potting adhesive, the silane coupling agent is 3-aminopropyltriethoxysilane.

[0018] It should be noted that 3-aminopropyltriethoxysilane (APTES), as a silane coupling agent, plays an important role in the preparation of composite materials. It chemically reacts with the surface of the substrate through its amino group, thereby enhancing the bonding force between the inorganic filler and the polymer, further improving the stability and performance of the composite material.

[0019] In addition, the present invention provides a thermally conductive potting adhesive prepared by the above-mentioned preparation method, wherein the thermally conductive potting adhesive comprises component A, component B and a pore-forming agent, wherein component A comprises 40 to 60 parts of vinyl silicone oil, 5 to 30 parts of BN1, 10 to 20 parts of modified PNIPAM@Al2O3 composite material and 1 to 3 parts of silane coupling agent; component B comprises 80 to 90 parts of hydrogen-containing silicone oil and 0.1 to 0.5 parts of a platinum catalyst.

[0020] It should be noted that in the preparation method of the thermal conductive potting glue provided by the invention, the thermal conductive potting glue is composed of component A, component B and a pore-forming agent. Component A mainly includes vinyl silicone oil, boron nitride (BN), modified PNIPAM@Al2O3 composite material and silane coupling agent. Among them, vinyl silicone oil as a base material provides good adhesion and processability, boron nitride (BN) plays the role of thermal conductive filler, modified PNIPAM@Al2O3 composite material provides temperature control performance to adjust thermal conductivity to achieve temperature adaptive regulation, and the modified PNIPAM@Al2O3 composite material improves the dispersibility between the filler and the matrix, reduces the aggregation and agglomeration phenomenon between particles, and avoids the increase in viscosity caused by aggregation. The silane coupling agent is used to improve the interface bonding between the modified PNIPAM@Al2O3 composite material and the vinyl silicone oil. Component B is composed of hydrogen-containing silicone oil and a platinum catalyst, wherein the hydrogen-containing silicone oil and the vinyl silicone oil undergo a cross-linking reaction through the action of the catalyst, and the platinum catalyst promotes the reaction. The pore-forming agent is used to form a microporous structure in the potting compound, further adjusting its thermal conductivity and thermal stability. The introduction of micropores can improve the temperature control performance of the potting compound, so that it can maintain a good thermal management effect under different temperature conditions. By precisely controlling the proportion and formula of each component, the thermally conductive potting compound provided by the present invention can maintain good thermal conductivity and stability in a high temperature environment, and is suitable for the packaging of electronic devices and other high-demand thermal management applications.

[0021] The thermally conductive potting adhesive and the preparation method thereof provided by the present invention have significant beneficial effects. First, the prepared thermally conductive potting adhesive has good temperature responsiveness, and its thermal conductivity can effectively reduce heat conduction at low temperatures, and can improve thermal conductivity at high temperatures, ensuring efficient heat dissipation performance. This temperature control characteristic enables it to maintain excellent thermal management functions under different working environments, thereby avoiding performance degradation or condensation of the equipment due to temperature changes. Secondly, by using a combination of modified PNIPAM@Al2O3 composite materials and pretreated Al2O3 nanoparticles, the dispersibility and stability of the material are significantly enhanced, the bonding force between the filler and the matrix is ​​improved, and the overall performance of the thermally conductive adhesive is improved. In addition, the pore-forming agent used introduces a microporous structure into the colloid, further optimizing the temperature control characteristics of the material, so that the thermally conductive adhesive can maintain excellent thermal conductivity under different temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 This is the infrared spectrum of the PNIPAM@Al2O3 composite material prepared in Example 1. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0027] Example

[0028] Example 1

[0029] Example 1 provides a thermally conductive potting compound and a preparation method thereof, wherein the thermally conductive potting compound includes component A, component B and sodium dodecyl sulfate, the component A includes 40 parts of vinyl silicone oil, 30 parts of BN, 15 parts of modified PNIPAM@Al2O3 composite material and 3 parts of 3-aminopropyltriethoxysilane; the component B includes 90 parts of hydrogenated silicone oil and 0.3 parts of a platinum catalyst.

[0030] The preparation method of the thermal conductive potting glue comprises the following technical steps:

[0031] Step S1. dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 30wt% N-isopropylacrylamide solution, adding triethylchlorosilane, wherein the triethylchlorosilane is 1wt% relative to the mass of the N-isopropylacrylamide, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution, wherein the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 1:1, and after being fully stirred, heating to 70°C to form a modified PNIPAM@Al2O3 composite material; wherein the preparation method of the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 800°C for 2h;

[0032] Step S2. Add 30 parts of BN, 15 parts of modified PNIPAM@Al2O3 composite material and 3 parts of 3-aminopropyltriethoxysilane to 40 parts of vinyl silicone oil, and disperse by high-speed shear to obtain component A;

[0033] Step S3. Mixing 90 parts of hydrogen-containing silicone oil with 0.3 parts of a platinum catalyst to obtain component B;

[0034] Step S4. Component A and component B are mixed at a mass ratio of 10:1, and sodium dodecyl sulfate is added and mixed, wherein the sodium dodecyl sulfate is 0.1wt% relative to the total mass of component A and component B, to obtain a thermally conductive potting adhesive.

[0035] Example 2

[0036] Example 2 provides a thermally conductive potting compound and a preparation method thereof, wherein the thermally conductive potting compound includes component A, component B and sodium dodecyl sulfate, the component A includes 60 parts of vinyl silicone oil, 15 parts of BN, 10 parts of modified PNIPAM@Al2O3 composite material and 2 parts of 3-aminopropyltriethoxysilane; the component B includes 80 parts of hydrogenated silicone oil and 0.1 parts of platinum catalyst.

[0037] The preparation method of the thermal conductive potting glue comprises the following technical steps:

[0038] Step S1. dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 20wt% N-isopropylacrylamide solution, adding triethylchlorosilane, wherein the triethylchlorosilane is 2wt% relative to the mass of the N-isopropylacrylamide, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution, wherein the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 3:1, and after being fully stirred, heating to 50°C to form a modified PNIPAM@Al2O3 composite material; wherein the preparation method of the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 700°C for 4h;

[0039] Step S2. Add 15 parts of BN, 10 parts of modified PNIPAM@Al2O3 composite material and 2 parts of 3-aminopropyltriethoxysilane to 60 parts of vinyl silicone oil, and disperse by high-speed shear to obtain component A;

[0040] Step S3. Mixing 80 parts of hydrogen-containing silicone oil with 0.1 parts of a platinum catalyst to obtain component B;

[0041] Step S4. Component A and component B are mixed at a mass ratio of 10:1, and sodium dodecyl sulfate is added and mixed, wherein the sodium dodecyl sulfate accounts for 0.5 wt % of the total mass of component A and component B, to obtain a thermally conductive potting adhesive.

[0042] Example 3

[0043] Example 3 provides a thermally conductive potting compound and a preparation method thereof, wherein the thermally conductive potting compound includes component A, component B and sodium dodecyl sulfate, the component A includes 50 parts of vinyl silicone oil, 20 parts of BN, 15 parts of modified PNIPAM@Al2O3 composite material and 1 part of 3-aminopropyltriethoxysilane; the component B includes 90 parts of hydrogenated silicone oil and 0.5 parts of a platinum catalyst.

[0044] The preparation method of the thermal conductive potting glue comprises the following technical steps:

[0045] Step S1. dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 10wt% N-isopropylacrylamide solution, adding triethylchlorosilane, wherein the triethylchlorosilane is 1wt% relative to the mass of the N-isopropylacrylamide, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution, wherein the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 2:1, and after being fully stirred, heating to 80°C to form a modified PNIPAM@Al2O3 composite material; wherein the preparation method of the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 600°C for 3h;

[0046] Step S2. Add 20 parts of BN, 15 parts of modified PNIPAM@Al2O3 composite material and 1 part of 3-aminopropyltriethoxysilane to 50 parts of vinyl silicone oil, and disperse by high-speed shear to obtain component A;

[0047] Step S3. Mixing 90 parts of hydrogen-containing silicone oil with 0.5 parts of a platinum catalyst to obtain component B;

[0048] Step S4. Component A and component B are mixed at a mass ratio of 10:1, and sodium dodecyl sulfate is added and mixed, wherein the sodium dodecyl sulfate accounts for 0.3 wt % of the total mass of component A and component B, to obtain a thermally conductive potting adhesive.

[0049] Example 4

[0050] Example 4 provides a thermally conductive potting compound and a preparation method thereof, wherein the thermally conductive potting compound includes component A, component B and sodium dodecyl sulfate, the component A includes 40 parts of vinyl silicone oil, 20 parts of BN, 20 parts of modified PNIPAM@Al2O3 composite material and 1 part of 3-aminopropyltriethoxysilane; the component B includes 85 parts of hydrogenated silicone oil and 0.2 parts of a platinum catalyst.

[0051] The preparation method of the thermal conductive potting glue comprises the following technical steps:

[0052] Step S1. dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 20wt% N-isopropylacrylamide solution, adding triethylchlorosilane, wherein the triethylchlorosilane is 3wt% relative to the mass of the N-isopropylacrylamide, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution, wherein the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 2:1, and after being fully stirred, heating to 60°C to form a modified PNIPAM@Al2O3 composite material; wherein the preparation method of the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 800°C for 3h;

[0053] Step S2. Add 20 parts of BN, 20 parts of modified PNIPAM@Al2O3 composite material and 1 part of 3-aminopropyltriethoxysilane to 40 parts of vinyl silicone oil, and disperse by high-speed shear to obtain component A;

[0054] Step S3. Mixing 85 parts of hydrogen-containing silicone oil with 0.2 parts of a platinum catalyst to obtain component B;

[0055] Step S4. Component A and component B are mixed at a mass ratio of 10:1, and sodium dodecyl sulfate is added and mixed, wherein the sodium dodecyl sulfate is 0.1wt% relative to the total mass of component A and component B, to obtain a thermally conductive potting adhesive.

[0056] Example 5

[0057] Example 5 provides a thermally conductive potting adhesive and a preparation method thereof, wherein the thermally conductive potting adhesive includes component A, component B and sodium dodecyl sulfate, the component A includes 50 parts of vinyl silicone oil, 15 parts of BN, 15 parts of modified PNIPAM@Al2O3 composite material and 1 part of 3-aminopropyltriethoxysilane; the component B includes 85 parts of hydrogenated silicone oil and 0.2 parts of platinum catalyst.

[0058] The preparation method of the thermal conductive potting glue comprises the following technical steps:

[0059] Step S1. dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 20wt% N-isopropylacrylamide solution, adding triethylchlorosilane, wherein the triethylchlorosilane is 3wt% relative to the mass of the N-isopropylacrylamide, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution, wherein the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 1:1, and after being fully stirred, heating to 80°C to form a modified PNIPAM@Al2O3 composite material; wherein the preparation method of the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 800°C for 3h;

[0060] Step S2. Add 15 parts of BN, 15 parts of modified PNIPAM@Al2O3 composite material and 1 part of 3-aminopropyltriethoxysilane to 50 parts of vinyl silicone oil, and disperse by high-speed shear to obtain component A;

[0061] Step S3. Mixing 85 parts of hydrogen-containing silicone oil with 0.2 parts of a platinum catalyst to obtain component B;

[0062] Step S4. Component A and component B are mixed at a mass ratio of 10:1, and sodium dodecyl sulfate is added and mixed, wherein the sodium dodecyl sulfate is 0.1wt% relative to the total mass of component A and component B, to obtain a thermally conductive potting adhesive.

[0063] Examples 6 to 10

[0064] The difference between Examples 6 to 10 and Example 5 is that the mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is specifically shown in Table 1 below.

[0065] Table 1

[0066]

[0067] Comparison Example

[0068] Comparative Example 1

[0069] The difference between the comparative example 1 and the example 1 is that the Al2O3 nanoparticles used in step S2 are not pretreated.

[0070] Comparative Example 2

[0071] The difference between the comparative example 2 and the example 2 is that the triethylchlorosilane is replaced by ammonium persulfate.

[0072] Comparative Example 3

[0073] The difference between this comparative example and Example 3 is that sodium lauryl sulfate is removed.

[0074] Performance testing

[0075] Viscosity: The viscosity of AB mixed and stirred for 5 minutes was tested using a rotational viscometer at 25°C.

[0076] Thermal conductivity: The thermal conductivity of the potting compound after curing was measured using a steady-state heat flow test. The sample diameter was 20 mm, the thickness was 2 mm, and the test temperature was 0°C to 60°C.

[0077] Agglomeration experiment: Through visual observation, preliminarily determine whether agglomeration has occurred in the potting glue sample.

[0078] Table 2 Experimental data of Examples 1 to 4 and Comparative Examples 1 to 3

[0079]

[0080]

[0081] Combined with Example 1 and Figure 1 It can be seen that 3450cm -1 The broad peak at 3300 cm-1 is attributed to the OH stretching vibration of Si-OH, indicating partial hydrolysis of triethylsilyl chloride. -1 The broad peak at 2900 cm-1 is the NH stretching vibration of the amide group, indicating the formation of hydrogen bonds between PNIPAM molecules. -1 The absorption peaks are derived from the CH stretching vibrations of ethyl (-C2H5) and isopropyl (-CH(CH3)2), which confirms the existence of alkyl chains. -1 The strong peaks at 1550cm -1 The medium-strong peaks at 1450 cm correspond to the C=O stretching vibration of the amide I band and the CN stretching vibration of the amide II band, confirming the polymerization of the acrylamide unit. -1 The absorption peak at 1600 cm is attributed to the CH bending vibration in the PNIPAM side chain. -1 The weak absorption peak at 1080cm may be related to the C=C double bond in the incompletely polymerized NIPAM monomer, suggesting that there may be residual incompletely reacted monomers. -1 The absorption peak is attributed to Si-O-Al vibration, indicating that triethylsilyl chloride is bonded to the Al2O3 surface through silicon-oxygen bonds. -1 The peak is the vibration of Si-C bond, confirming the structural characteristics of triethylchlorosilane. Overall, the spectral characteristics indicate that PNIPAM has been successfully polymerized and bonded to the Al2O3 substrate through Si-O-Al bonds.

[0082] In combination with Examples 1 to 4 and Table 2, it can be seen that the viscosity of the thermally conductive potting compound prepared by the components and preparation process of the present application ranges from 784 to 823 mPa·s, and no agglomeration occurs during the test. Specifically, the thermal conductivity of the samples in the embodiments under different temperature conditions (from 0°C to 60°C) shows the expected temperature responsiveness. At low temperatures, the thermal conductivity is low, indicating that the potting compound effectively slows down heat conduction at lower temperatures; at high temperatures, the thermal conductivity is large, ensuring efficient heat dissipation, thereby avoiding equipment performance degradation or condensation due to too low or too high temperatures. These results show that the thermally conductive potting compound prepared by the present invention not only has good temperature control performance, but also has good dispersibility and stability, and is suitable for thermal management of high-power electronic equipment.

[0083] Combining Example 1, Control Example 1 and Table 2, it can be seen that the thermal conductive potting glue prepared in Control Example 1 is inferior to that in Example 1 in many aspects. First, the viscosity of Control Example 1 increased significantly, reaching 954mPa·s, compared with 814mPa·s in Example 1, indicating that a more obvious viscosity increase occurred during the preparation process, which may be related to the agglomeration phenomenon between particles. Actual observations also found that a small amount of agglomeration occurred in Control Example 1, resulting in poor dispersibility and stability. Secondly, the test results of thermal conductivity show that the response function of the thermal conductivity of Control Example 1 at different temperatures is not obvious, mainly because the Al2O3 nanoparticles have not been pretreated, resulting in poor surface properties of the PNIPAM@Al2O3 composite material, and the bonding force between the filler and the matrix is ​​not strong, thus affecting the overall performance of the material.

[0084] Combining Example 2, Control Example 2 and Table 2, it can be seen that the thermal conductive potting glue prepared in Control Example 2 is inferior to that in Example 2 in many aspects. In Control Example 2, the viscosity increased significantly, reaching 1089 mPa·s, compared with 784 mPa·s in Example 2, indicating that a more obvious viscosity increase occurred during the preparation process. The thermal conductivity test results showed that the thermal conductivity responsiveness of Control Example 2 was poor, especially at high temperatures, the thermal conductivity increased slowly, and failed to show obvious temperature adaptive regulation function. Ammonium persulfate failed to effectively promote the polymerization of NIPAM on the surface of Al2O3 to form a uniform PNIPAM@Al2O3 composite material, resulting in insufficient functional group grafting on the surface of the composite material, thereby affecting the compatibility between the filler and the matrix. This lack of functional group grafting may cause the particles of the composite material to be difficult to disperse in the colloid and prone to agglomeration, which in turn leads to increased viscosity and affects its temperature control performance.

[0085] It can be seen from Example 3, Comparative Example 3 and Table 2 that the thermal conductivity of the potting glue prepared in Example 3 responds more obviously to temperature than that in Comparative Example 3, mainly because sodium dodecyl sulfate is used as a pore-forming agent, and the thermal conductivity is adjusted under different temperature conditions by introducing a microporous structure into the colloid. When the temperature rises, NIPAM shows temperature responsiveness, changes to a flowing state, the polymer chain becomes more flexible, and the fluidity is enhanced. At this time, the micropores provide a channel for heat conduction, allowing heat to be conducted more easily in the colloid, thereby improving the thermal conductivity. When the temperature drops, NIPAM returns to a solid state, the polymer chain shrinks, and becomes more dense. At this time, the microporous structure plays an isolating role, reducing the path of heat conduction, resulting in a decrease in thermal conductivity. The presence of micropores can enable the thermally conductive potting glue to maintain good thermal management performance under different environments through this temperature change adjustment mechanism, which can not only improve the thermal conductivity efficiency at high temperatures, but also reduce heat conduction at low temperatures, and optimize the temperature control performance of the material.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a thermally conductive potting compound, characterized in that: The technical steps include: Step S1. Add BN, modified PNIPAM@Al2O3 composite material and silane coupling agent to vinyl silicone oil, and disperse by high-speed shear to obtain component A; Step S2. mixing the hydrogen-containing silicone oil with the platinum catalyst to obtain component B; Step S3: Component A and component B are mixed at a mass ratio of 10:1, and then a pore-forming agent is added to the mixture to obtain a thermally conductive potting adhesive.

2. The method for preparing the thermally conductive potting adhesive according to claim 1, characterized in that: The preparation steps of the modified PNIPAM@Al2O3 composite material include the following steps: dissolving N-isopropylacrylamide (NIPAM) monomer in deionized water to prepare a 10wt% to 30wt% N-isopropylacrylamide solution, adding a catalyst, and then adding pretreated Al2O3 nanoparticles to the NIPAM monomer solution, stirring the mixture thoroughly, and heating the mixture to 50-80°C to form a modified PNIPAM@Al2O3 composite material.

3. The method for preparing the thermally conductive potting adhesive according to claim 2, characterized in that: The method for preparing the pretreated Al2O3 nanoparticles comprises: heating the Al2O3 nanoparticles at 600°C to 800°C for 2 to 4 hours.

4. The method for preparing the thermally conductive potting adhesive according to claim 2, characterized in that: The mass ratio between the pretreated Al2O3 nanoparticles and the NIPAM is 1:1 to 3:

1.

5. The method for preparing the thermally conductive potting adhesive according to claim 1, characterized in that: The pore-forming agent is sodium dodecyl sulfate, and the sodium dodecyl sulfate accounts for 0.1 wt% to 0.5 wt% of the total mass of the A component and the B component.

6. The method for preparing the thermally conductive potting adhesive according to claim 2, characterized in that: The catalyst is triethylsilyl chloride, and the triethylsilyl chloride accounts for 1 wt % to 3 wt % of the mass of the N-isopropylacrylamide.

7. The method for preparing the thermally conductive potting adhesive according to claim 1, characterized in that: The silane coupling agent is 3-aminopropyltriethoxysilane.

8. A thermally conductive potting adhesive prepared by the preparation method according to claim 1, characterized in that: The thermal conductive potting compound includes component A, component B and a pore-forming agent. Component A includes 40 to 60 parts of vinyl silicone oil, 15 to 30 parts of BN1, 10 to 20 parts of modified PNIPAM@Al2O3 composite material and 1 to 3 parts of silane coupling agent; component B includes 80 to 90 parts of hydrogen-containing silicone oil and 0.1 to 0.5 parts of platinum catalyst.

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