A silicone heat-conducting gel and a method for preparing the same

Abstract

This application provides an organosilicon thermally conductive gel and its preparation method, belonging to the technical field of thermal interface materials. The organosilicon thermally conductive gel comprises an organosilicon matrix, a thermally conductive filler system, a catalyst, and an inhibitor; the organosilicon matrix comprises terminal vinyl polydimethylsiloxane, side-chain hydrogen-containing polydimethylsiloxane, and branched vinyl silicone oil; the thermally conductive filler system comprises surface-modified spherical aluminum powder and surface-hydroxylated tetraneedle-shaped zinc oxide; the surface-modified spherical aluminum powder comprises a spherical aluminum core and a silica layer coating the surface of the aluminum core, the surface of the silica layer being grafted with a vinyl-containing silane coupling agent; the surface-hydroxylated tetraneedle-shaped zinc oxide is obtained by introducing hydroxyl groups onto its surface through alkaline solution treatment. The synergistic effect of the surface-modified spherical aluminum powder and the surface-hydroxylated tetraneedle-shaped zinc oxide in this invention enables excellent thermal conductivity while ensuring good flexibility and low modulus of the gel material.

Description

Technical Field

[0001] This application relates to the field of thermal interface materials technology, and in particular to an organosilicon thermally conductive gel and its preparation method. Background Technology

[0002] With the development of the electronics and electrical appliance industry, increasingly higher requirements are being placed on the heat dissipation of electronic components, making thermal interface materials play an increasingly important role. Currently, the most commonly used thermal interface materials are thermal grease, thermal silicone pads, and thermal gels. Among them, thermal gels can avoid solid-liquid separation and eventual drying through their own vulcanization; they can also fill irregular thermal interfaces, thus achieving a heat dissipation effect.

[0003] However, existing thermal conductive gels often have the following two problems: On the one hand, in order to achieve high thermal conductivity, a large amount of thermal conductive powder (>70 vol%) is filled, resulting in excessive system viscosity, difficult construction, difficulty in automatic dispensing, and easy damage to precision electronic components; on the other hand, powders with a single particle size or random mixture are prone to forming thermally conductive islands in the matrix, resulting in obstructed thermal conduction paths and low filler utilization, thus affecting the use of thermal conductive gels. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide an organosilicon thermally conductive gel and a method for preparing the same.

[0005] Specifically, the first aspect of this application provides an organosilicon thermally conductive gel, comprising: an organosilicon matrix, a thermally conductive filler system, a catalyst, and an inhibitor;

[0006] The organosilicon matrix includes terminal vinyl polydimethylsiloxane, side-chain hydrogen-containing polydimethylsiloxane, and branched vinyl silicone oil, wherein the vinyl functionality of the branched vinyl silicone oil is 0.08-0.15 mol / 100g;

[0007] The thermally conductive filler system comprises surface-modified spherical aluminum powder and surface-hydroxylated tetrapter-shaped zinc oxide;

[0008] The surface-modified spherical aluminum powder includes a first modified aluminum powder with a D50 particle size of 5-10 μm, a second modified aluminum powder with a D50 particle size of 15-25 μm, and a third modified aluminum powder with a D50 particle size of 25-40 μm. The structure of the first modified aluminum powder, the second modified aluminum powder, and the third modified aluminum powder all includes a spherical aluminum core and a silicon dioxide layer covering the surface of the aluminum core. The surface of the silicon dioxide layer is grafted with a vinyl-containing silane coupling agent. The surface-hydroxylated tetraneedle-shaped zinc oxide is obtained by introducing hydroxyl groups on its surface through alkaline solution treatment.

[0009] Furthermore, the organosilicon thermal conductive gel, by weight, comprises 65-80 parts of terminal vinyl polydimethylsiloxane in the organosilicon matrix, 15-30 parts of side-chain hydrogen-containing polydimethylsiloxane, and 5-15 parts of branched vinyl silicone oil.

[0010] The thermally conductive filler system comprises 700-850 parts of surface-modified spherical aluminum powder and 100-250 parts of surface-hydroxylated tetraneedle zinc oxide.

[0011] Furthermore, the length of each needle in the tetra-needle zinc oxide is 1-10 μm.

[0012] Furthermore, the mass ratio of the first modified aluminum powder, the second modified aluminum powder, the third modified aluminum powder, and the tetraneedle-shaped zinc oxide is 1.8-2.2 : 2.8-3.3 : 3.6-4.2 : 0.8-1.2, preferably 2:3:4:1.

[0013] Furthermore, the catalyst is a platinum catalyst;

[0014] And / or, the inhibitor is 1-ethynyl-1-cyclohexanol and diethyl maleate.

[0015] A second aspect of this application provides a method for preparing an organosilicon thermally conductive gel, comprising the following steps:

[0016] S1: Surface-coating and grafting treatment is performed on spherical aluminum powder to obtain surface-modified spherical aluminum powder; hydroxylation treatment is performed on tetraneedle-shaped zinc oxide to obtain surface-hydroxylated tetraneedle-shaped zinc oxide.

[0017] S2: The surface-hydroxylated tetrane needle-shaped zinc oxide is first mixed and dispersed with branched vinyl silicone oil to form a premixed network;

[0018] S3: Add vinyl-terminated polydimethylsiloxane, inhibitor, and hydrogen-containing polydimethylsiloxane to the premixed network, and add surface-modified spherical aluminum powder in batches for a second mixing and dispersion.

[0019] S4: Add catalyst, perform third mixing, dispersion and degassing to obtain the organosilicon thermal conductive gel.

[0020] Furthermore, in step S2, the first mixing and dispersion temperature is 20-30℃, and the total dispersion time is 30-60 minutes.

[0021] Furthermore, in step S3, the surface-modified spherical aluminum powder is added in at least two batches: first, the third modified aluminum powder is added, and then the first modified aluminum powder and the second modified aluminum powder are added.

[0022] And / or, the second mixing dispersion includes alternating high-shear phases and low-shear phases, wherein the high-shear phase has an orbital speed of 15-25 rpm and a rotational speed of 50-70 rpm, lasting 1-3 minutes; the low-shear phase has an orbital speed of 3-8 rpm and a rotational speed of 8-15 rpm, lasting 2-4 minutes; and the high-shear phase and low-shear phase are alternated 4-6 times.

[0023] Further, in step S1, the surface coating and grafting treatment of the spherical aluminum powder includes: forming a silica coating layer on the surface of the spherical aluminum powder using a sol-gel method, and then grafting the silica coating layer onto the surface using a vinyl-containing silane coupling agent.

[0024] Further, in step S1, the hydroxylation treatment of the tetraneedle zinc oxide includes: soaking the tetraneedle zinc oxide in an alkaline solution with a concentration of 1-3 wt%.

[0025] The present invention has the following beneficial effects:

[0026] The thermally conductive filler system of this invention uses a combination of surface-modified spherical aluminum powder and surface-hydroxylated tetragonal zinc oxide. The two work synergistically: the spherical aluminum powder provides the main support for the thermally conductive network with its high packing density and good flowability, while the tetragonal zinc oxide, with its unique three-dimensional needle-like structure, can connect adjacent spherical aluminum powder particles with a lower filling amount, constructing a more continuous and smooth thermally conductive path, significantly reducing the phenomenon of thermally conductive islands, improving the filler utilization rate, and thus achieving high thermal conductivity with a relatively low volume fraction filling.

[0027] This invention also modifies spherical aluminum powder by coating it with silica and grafting it with vinyl silane coupling agent, which not only solves the problem of easy oxidation of aluminum powder, but also enhances its interfacial compatibility and chemical bonding with the organosilicon matrix; the surface-hydroxylated tetrane needle-like zinc oxide can interact with the vinyl or other groups in the branched vinyl silicone oil through hydroxyl groups, further promoting the uniform dispersion of filler in the matrix and helping to form a premixed network.

[0028] The introduction of branched vinyl silicone oil into the organosilicon matrix provides more reaction sites compared to traditional linear silicone oil, allowing for better crosslinking with functional groups on the surface of the modified filler and other matrix components (terminated vinyl polydimethylsiloxane, side-chain hydrogen-containing polydimethylsiloxane). This ensures that the system has an appropriate crosslinking density to maintain structural stability while avoiding increased brittleness and decreased flowability caused by excessive crosslinking. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0030] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0031] An embodiment of the first aspect of this application provides an organosilicon thermally conductive gel, comprising: an organosilicon matrix, a thermally conductive filler system, a catalyst, and an inhibitor;

[0032] The organosilicon matrix includes terminal vinyl polydimethylsiloxane (Dow Corning PMX-0345Z), side-chain hydrogen-containing polydimethylsiloxane (PDMS-H), and branched vinyl silicone oil (IOTA 272), wherein the vinyl functionality of the branched vinyl silicone oil is 0.08-0.15 mol / 100g.

[0033] The thermally conductive filler system comprises surface-modified spherical aluminum powder and surface-hydroxylated tetrapter-shaped zinc oxide;

[0034] The surface-modified spherical aluminum powder includes a first modified aluminum powder with a D50 particle size of 5-10 μm, a second modified aluminum powder with a D50 particle size of 15-25 μm, and a third modified aluminum powder with a D50 particle size of 25-40 μm. The structure of the first modified aluminum powder, the second modified aluminum powder, and the third modified aluminum powder all includes a spherical aluminum core and a silicon dioxide layer covering the surface of the aluminum core. The surface of the silicon dioxide layer is grafted with a vinyl-containing silane coupling agent. The surface-hydroxylated tetraneedle-shaped zinc oxide is obtained by introducing hydroxyl groups on its surface through alkaline solution treatment.

[0035] In the described organosilicon matrix, terminal vinyl polydimethylsiloxane serves as the main base polymer, providing a linear molecular chain structure. The vinyl groups at the ends of its molecular chain can undergo addition reactions with the Si-H bonds in the side-chain hydrogen-containing polydimethylsiloxane, making it a key component in forming the cross-linked network structure and imparting basic mechanical properties and structural support to the gel. The side-chain hydrogen-containing polydimethylsiloxane acts as a cross-linking agent; its Si-H bonds on the side chains can undergo hydrosilylation reactions with the vinyl groups in terminal vinyl polydimethylsiloxane and branched vinyl silicone oil. By adjusting its dosage, the density of the cross-linked network can be controlled, thereby affecting the gel's hardness, elasticity, and other mechanical properties. Branched vinyl silicone oils possess a multi-branched structure with a vinyl functionality of 0.08-0.15 mol / 100g. Their molecular chains contain multiple vinyl functional groups, which, in addition to participating in hydrosilylation reactions, can form more complex cross-linking points in the system due to their branched structure, increasing the degree of network entanglement. This, in turn, enhances the tear resistance and high-temperature resistance while ensuring good elasticity and flexibility of the gel. Furthermore, the unique structure of branched vinyl silicone oils allows for stronger interactions with surface-hydroxylated tetraneedle-shaped zinc oxide. During the first mixing and dispersion process in step S2, this enables more effective adsorption and encapsulation of tetraneedle-shaped zinc oxide particles, promoting the stable formation of the premixed network and providing a good structural basis for the subsequent uniform dispersion of spherical aluminum powder.

[0036] The length of each needle in the tetra-needle zinc oxide is 1-5 μm. The tetra-needle zinc oxide has the CAS number 1314-13-2. The mass ratio of the first modified aluminum powder, the second modified aluminum powder, the third modified aluminum powder, and the tetra-needle zinc oxide is 1.8-2.2 : 2.8-3.3 : 3.6-4.2 : 0.8-1.2; preferably 2:3:4:1.

[0037] The use of first, second, and third modified aluminum powders with different particle sizes achieves a denser packing effect through a gradient combination of different particle sizes. The third modified aluminum powder, with a D50 particle size of 25-40 μm, acts as a large particle skeleton, forming a preliminary loose packing structure in the system and providing space for the filling of small and medium-sized particles. The second modified aluminum powder, with a D50 particle size of 15-25 μm, fills the gaps between the third modified aluminum powder particles, reducing the porosity formed by the large particle packing. The first modified aluminum powder, with a D50 particle size of 5-10 μm, further fills the tiny gaps between the second and third modified aluminum powders, thus significantly improving the overall packing density of the thermally conductive filler. This multi-level particle size synergistic packing method reduces the air content in the system, increases the contact area between thermally conductive particles, lays the foundation for constructing a continuous and efficient thermal conduction path, and thus improves the thermal conductivity of the thermally conductive gel. Meanwhile, a reasonable particle size distribution can also improve the rheological properties of the system, avoid the problem of a sharp increase in viscosity caused by powders of a single particle size, and help to increase the maximum filling amount of filler and ensure that the material has good workability.

[0038] In this embodiment, the organosilicon matrix comprises 65-80 parts by weight of vinyl-terminated polydimethylsiloxane, for example, 65 parts, 70 parts, 75 parts or 80 parts.

[0039] The side chain contains 15-30 parts of hydrogen-containing polydimethylsiloxane, for example, 15 parts, 20 parts, 25 parts or 30 parts;

[0040] 5-15 parts of branched vinyl silicone oil, for example, 5 parts, 8 parts, 10 parts, 12 parts or 15 parts.

[0041] The thermally conductive filler system, by weight, comprises 700-850 parts of surface-modified spherical aluminum powder, specifically 700 parts, 750 parts, 800 parts, or 850 parts.

[0042] The surface-hydroxylated tetraneedle zinc oxide is 100-250 parts, specifically 100 parts, 130 parts, 150 parts, 180 parts, 200 parts, 220 parts or 250 parts.

[0043] The catalyst is a platinum catalyst (such as a Karstedt catalyst), and its addition amount is 0.001-0.01 parts by weight of the total organosilicon matrix, for example, 0.001 parts, 0.003 parts, 0.005 parts, 0.008 parts or 0.01 parts.

[0044] The inhibitor is 1-ethynyl-1-cyclohexanol and diethyl maleate; the amount added is 0.05-0.3 parts by weight of the total organosilicon matrix, for example 0.05 parts, 0.1 parts, 0.2 parts or 0.3 parts;

[0045] The inhibitors are 1-ethynyl-1-cyclohexanol and diethyl maleate, which inhibit premature cross-linking reactions of the gel during storage and processing, ensuring good storage stability and process operation window of the system.

[0046] An embodiment of the second aspect of this application provides a method for preparing an organosilicon thermally conductive gel, comprising the following steps:

[0047] S1: Surface-coating and grafting treatment is performed on spherical aluminum powder to obtain surface-modified spherical aluminum powder; hydroxylation treatment is performed on tetraneedle-shaped zinc oxide to obtain surface-hydroxylated tetraneedle-shaped zinc oxide.

[0048] S2: The surface-hydroxylated tetrane needle-shaped zinc oxide is first mixed and dispersed with branched vinyl silicone oil to form a premixed network;

[0049] S3: Add vinyl-terminated polydimethylsiloxane, hydrogen-containing polydimethylsiloxane and inhibitor to the premixed network, then add the third modified aluminum powder, then add the first modified aluminum powder and the second modified aluminum powder, and carry out the second mixing and dispersion.

[0050] S4: Add catalyst, perform third mixing, dispersion and degassing to obtain the organosilicon thermal conductive gel.

[0051] In step S1, the surface coating and grafting treatment of the spherical aluminum powder includes:

[0052] (1) Disperse spherical aluminum powder (D50=1-30μm) in a mixture of ethanol / water / 25% ammonia (volume ratio 4:1:0.1) and sonicate for 30 minutes; under constant temperature stirring at 40℃, add ethanol solution of tetraethyl orthosilicate (TEOS) (30g TEOS dissolved in 100ml ethanol) dropwise at a rate of 1 ml / min; after the addition is complete, continue the reaction for 6 hours; after the reaction is complete, centrifuge, wash 3 times with ethanol, and vacuum dry at 80℃ for 12 hours to obtain spherical aluminum powder with a silica coating.

[0053] (2) Spherical aluminum powder with a silica coating is dispersed in toluene, vinyltriethoxysilane and glacial acetic acid are added, and the mixture is heated to 80°C and refluxed for 4 hours under nitrogen protection. After the reaction is completed, the mixture is washed successively with toluene and ethanol, and then vacuum dried at 100°C for 4 hours to graft a vinyl-containing silane coupling agent onto the surface of the silica layer. The first modified aluminum powder, the second modified aluminum powder, and the third modified aluminum powder are prepared from spherical aluminum powders of different particle sizes through the above modification treatment.

[0054] In step S1, the hydroxylation treatment of tetraneedle zinc oxide includes: soaking the tetraneedle zinc oxide in a 1-3 wt% NaOH solution, mechanically stirring at 200 rpm for 60 minutes in a water bath at 45-55°C, and then washing until neutral and drying.

[0055] In step S2, the surface-hydroxylated tetrane needle-shaped zinc oxide and branched vinyl silicone oil are added to a mixing tank and run at a low speed (10 rpm revolution / 20 rpm rotation) for 10 minutes under a vacuum of -0.097 MPa and a temperature of 20-30°C to initially wet the powder. Then, the mixture is switched to a medium-high speed mode (15 rpm revolution / 40 rpm rotation) and dispersed for 40 minutes under the same vacuum and temperature to form a premixed network.

[0056] In step S3, vinyl-terminated polydimethylsiloxane, inhibitors (1-ethynyl-1-cyclohexanol and diethyl maleate), hydrogen-containing polydimethylsiloxane with side chains, and third modified aluminum powder are added to the premixed network. The mixture is continuously mixed for 30 minutes at a vacuum of -0.097 MPa and a temperature of 20-30°C in a medium-speed mode (12 rpm revolution / 30 rpm rotation).

[0057] Then, the first modified aluminum powder and the second modified aluminum powder are added; the vacuum degree is increased to -0.099 MPa, the temperature is 25-30℃, and alternating high-shear and low-shear stages are adopted. In the high-shear stage, the revolution speed is 15-25 rpm and the rotation speed is 50-70 rpm, lasting for 1-3 minutes; in the low-shear stage, the revolution speed is 3-8 rpm and the rotation speed is 8-15 rpm, lasting for 2-4 minutes; the number of cycles of alternating high-shear and low-shear stages is 4-6 times.

[0058] In step S4, the platinum catalyst is added to the stirred tank and mixed and degassed under vacuum (-0.099 MPa) and 25°C at a revolution speed of 5 rpm / rotation speed of 15 rpm for 60 minutes.

[0059] Example

[0060] The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.

[0061] Example 1

[0062] An organosilicon thermally conductive gel comprises the following raw materials in parts by weight:

[0063] The composition includes 110 parts of organosilicon matrix, 1000 parts of thermally conductive filler system, 0.001 parts of platinum catalyst, and 0.1 parts of inhibitor (1-ethynyl-1-cyclohexanol and diethyl maleate).

[0064] The organosilicon matrix comprises 70 parts of terminal vinyl polydimethylsiloxane, 30 parts of side-chain hydrogen-containing polydimethylsiloxane, and 10 parts of branched vinyl silicone oil.

[0065] The thermally conductive filler system comprises 200 parts of surface-modified first-modified aluminum powder (D50 particle size of 5μm), 300 parts of second-modified aluminum powder (D50 particle size of 20μm), 400 parts of third-modified aluminum powder (D50 particle size of 30μm), and 100 parts of surface-hydroxylated tetra-needle zinc oxide.

[0066] The length of a single needle in the tetra-needle zinc oxide is 3 μm; the tetra-needle zinc oxide was purchased from Qinghe County Chaotai Metal Materials Co., Ltd., CAS No.: 1314-13-2.

[0067] The preparation method of the organosilicon thermally conductive gel comprises the following steps:

[0068] S1: The steps for surface coating and grafting treatment of spherical aluminum powder are as follows:

[0069] (1) Disperse spherical aluminum powder in a mixture of ethanol / water / 25% ammonia (volume ratio 4:1:0.1), wherein the spherical aluminum powder and the mixture are mixed at a ratio of 1:1 (m / v) and ultrasonically dispersed for 30 minutes;

[0070] An ethanol solution of tetraethyl orthosilicate (30 g tetraethyl orthosilicate dissolved in 100 ml ethanol) was added dropwise at a rate of 1 ml / min under constant temperature stirring at 40℃. After the addition was complete, the reaction was continued for 6 hours. After the reaction was completed, the mixture was centrifuged, washed three times with ethanol, and dried under vacuum at 80℃ for 12 hours to obtain spherical aluminum powder with a silica coating.

[0071] (2) Spherical aluminum powder coated with silica layer is dispersed in toluene, wherein the mass-volume ratio of spherical aluminum powder to toluene is 1:2; vinyltriethoxysilane and glacial acetic acid are added, wherein the mass ratio of spherical aluminum powder to vinyltriethoxysilane and glacial acetic acid is 100:1.2:0.1; under nitrogen protection, it is heated to 80°C and refluxed for 4 hours. After the reaction is completed, it is washed with toluene and ethanol in sequence, and then vacuum dried at 100°C for 4 hours to graft vinyl-containing silane coupling agent onto the surface of silica layer; first modified aluminum powder, second modified aluminum powder and third modified aluminum powder are prepared by using spherical aluminum powder with different particle sizes.

[0072] The steps for hydroxylation treatment of tetrane needle-shaped zinc oxide are as follows:

[0073] The tetraneedle-shaped zinc oxide was soaked in a 2 wt% NaOH solution, mechanically stirred at 200 rpm for 60 minutes in a 50°C water bath, then washed until neutral and dried.

[0074] S2: Add the surface-hydroxylated tetraneedle zinc oxide and branched vinyl silicone oil to the mixing tank. Under a vacuum of -0.097 MPa and a temperature of 25°C, run at a low speed (10 rpm revolution / 20 rpm rotation) for 10 minutes to initially wet the powder. Switch to a medium-high speed mode (15 rpm revolution / 40 rpm rotation) and continue to disperse for 40 minutes under the same vacuum and temperature to form a premixed network.

[0075] S3: Add vinyl-terminated polydimethylsiloxane, hydrogen-containing polydimethylsiloxane and inhibitor, as well as third modified aluminum powder to the premixed network, and continuously mix for 30 minutes at medium speed (12 rpm revolution / 30 rpm rotation) under vacuum of -0.097 MPa and temperature of 25°C.

[0076] Then, the first modified aluminum powder and the second modified aluminum powder were added; under a vacuum of -0.099 MPa and a temperature of 25°C, alternating high-shear mixing and low-shear relaxation were performed.

[0077] During the high-shear phase, the revolution speed is 20 rpm and the rotation speed is 60 rpm, lasting for 2 minutes.

[0078] The revolution speed during the low shear phase is 5 rpm, the rotation speed is 12 rpm, and it lasts for 3 minutes; the number of cycles alternating between the high shear phase and the low shear phase is 5.

[0079] S4: Platinum catalyst was added to a stirred tank and mixed and degassed under vacuum (-0.099 MPa) and 25°C at a revolution speed of 5 rpm / rotation speed of 15 rpm for 60 minutes to obtain organosilicon thermally conductive gel.

[0080] Example 2

[0081] This embodiment is basically the same as Embodiment 1, except that the thermally conductive filler system includes 190 parts of surface-modified first modified aluminum powder (D50 particle size is 5μm), 290 parts of second modified aluminum powder (D50 particle size is 20μm), 380 parts of third modified aluminum powder (D50 particle size is 30μm) and 140 parts of surface-hydroxylated tetraneedle zinc oxide.

[0082] Example 3

[0083] This embodiment is basically the same as that of embodiment 1, except that 100 parts of the organosilicon matrix and 950 parts of the thermally conductive filler system are used, including 75 parts of the terminal vinyl polydimethylsiloxane, 20 parts of the side-chain hydrogen-containing polydimethylsiloxane, and 5 parts of the branched vinyl silicone oil in the organosilicon matrix.

[0084] The thermally conductive filler system comprises 200 parts of surface-modified first-modified aluminum powder (D50 particle size of 5μm), 290 parts of second-modified aluminum powder (D50 particle size of 20μm), 370 parts of third-modified aluminum powder (D50 particle size of 30μm), and 90 parts of surface-hydroxylated tetraneedle-shaped zinc oxide.

[0085] Example 4

[0086] This embodiment is basically the same as Example 1, except that it contains 75 parts of terminal vinyl polydimethylsiloxane, 28 parts of side-chain hydrogen-containing polydimethylsiloxane, and 7 parts of branched vinyl silicone oil.

[0087] The thermally conductive filler system comprises 210 parts of surface-modified first modified aluminum powder (D50 particle size of 5 μm), 300 parts of second modified aluminum powder (D50 particle size of 20 μm), 400 parts of third modified aluminum powder (D50 particle size of 30 μm), and 90 parts of surface-hydroxylated tetraneedle-shaped zinc oxide.

[0088] Example 5

[0089] This embodiment is basically the same as Example 1, except that it contains 68 parts of terminal vinyl polydimethylsiloxane, 20 parts of side-chain hydrogen-containing polydimethylsiloxane, and 12 parts of branched vinyl silicone oil.

[0090] The thermally conductive filler system comprises 200 parts of surface-modified first modified aluminum powder (D50 particle size of 5 μm), 300 parts of second modified aluminum powder (D50 particle size of 20 μm), 380 parts of third modified aluminum powder (D50 particle size of 30 μm), and 120 parts of surface-hydroxylated tetraneedle-shaped zinc oxide.

[0091] Comparative Example 1

[0092] This comparative example is basically the same as Example 1, except that the surface-modified spherical aluminum powder is replaced with spherical aluminum powder (D50 particle size is 30μm); and the surface-hydroxylated tetraneedle zinc oxide is replaced with tetraneedle zinc oxide.

[0093] Comparative Example 2

[0094] This comparative example is basically the same as Example 1, except that the surface-modified spherical aluminum powder (D50 particle size of 30μm) is not subjected to surface vinyl grafting treatment.

[0095] Comparative Example 3

[0096] This comparative example is basically the same as Example 1, except that the thermally conductive filler does not use surface-modified spherical aluminum powder, but only surface-hydroxylated tetra-needle zinc oxide.

[0097] Comparative Example 4

[0098] This comparative example is basically the same as Example 1, except that the preparation method of the organosilicon thermal conductive gel is as follows: all powders and all liquid components are added at one time and dispersed at 200 rpm for 90 minutes under a vacuum of -0.097 MPa.

[0099] Experimental Case

[0100] The thermal conductivity, viscosity, and stability at -20°C for 1 month of the organosilicon thermally conductive gels of Examples 1-5 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0101] Table 1 Test results of Examples 1-5 and Comparative Examples 1-4

[0102]

[0103] As shown in Table 1, the organosilicon thermally conductive gels prepared in Examples 1-5 of this application all exhibit excellent comprehensive properties. Specifically, Example 1 achieved a thermal conductivity of 6.55 W / (m·K), along with a tensile strength of 0.11 MPa, an elongation at break of 260%, a viscosity of 82500 CP (10 rpm), and showed no sedimentation after one month of storage at -20°C, maintaining uniform performance. Example 3, by adjusting the composition of the organosilicon matrix and the ratio of thermally conductive fillers, further improved the thermal conductivity to 7.13 W / (m·K), demonstrating high potential for thermal conductivity. Examples 2 and 5, by optimizing the amount of tetrapod-shaped zinc oxide, maintained good mechanical properties and stability while ensuring good thermal conductivity (5.80 W / (m·K) and 6.18 W / (m·K), respectively).

[0104] Comparative Example 1, due to the lack of surface coating and graft modification of aluminum powder and the absence of hydroxylation treatment of tetraneedle zinc oxide, exhibited a significant decrease in thermal conductivity to 4.36 W / (m·K) and a substantial drop in elongation at break to 110%. This may be because the unmodified aluminum powder and tetraneedle zinc oxide lack functional groups with good compatibility with the organosilicon matrix, resulting in uneven dispersion of the powder in the matrix, increased interfacial thermal resistance, and weak bonding between the powder and the matrix, which easily leads to stress concentration under stress, thereby reducing the flexibility of the material.

[0105] In Comparative Example 2, the spherical aluminum powder was only coated with a silica layer without grafting vinyl groups, which resulted in a lack of active sites on its surface that could chemically bond with the vinyl groups in the organosilicon matrix. During the mixing process, it was difficult to form a stable network structure with the organosilicon molecular chains, causing the viscosity of the system to rise sharply beyond the range and making it impossible to form normally.

[0106] Comparative Example 3 used only surface-hydroxylated tetraneedle zinc oxide as a thermally conductive filler. Due to the limited thermal conductivity of a single tetraneedle zinc oxide, the thermal conductivity was only 2.1 W / (m·K), which is much lower than that of the product in the example. At the same time, the tensile strength was high (0.31 MPa) but the elongation at break was extremely low (45%), indicating that the material was brittle. This was due to the lack of synergistic filling and toughening effects of aluminum powder with different particle sizes.

[0107] Comparative Example 4 used a one-time feeding and high-speed dispersion preparation method, which failed to achieve stepwise construction of the premixed network and gradient dispersion of fillers with different particle sizes. This resulted in filler agglomerates in the system. Although the thermal conductivity reached 5.53 W / (m·K), the performance uniformity was poor, and the performance fluctuated greatly after being stored at -20℃ for 1 month. This indicates that the disordered mixing method cannot guarantee the stable dispersion and structural uniformity of the thermally conductive filler in the organosilicon matrix.

[0108] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An organosilicon thermally conductive gel, characterized in that, This includes the silicone matrix, thermally conductive filler system, catalyst, and inhibitor; The organosilicon matrix includes terminal vinyl polydimethylsiloxane, side-chain hydrogen-containing polydimethylsiloxane, and branched vinyl silicone oil, wherein the vinyl content in the branched vinyl silicone oil is 0.08-0.15 mol / 100g; The thermally conductive filler system comprises surface-modified spherical aluminum powder and surface-hydroxylated tetrapter-shaped zinc oxide; The surface-modified spherical aluminum powder includes a first modified aluminum powder with a D50 particle size of 5-10 μm, a second modified aluminum powder with a D50 particle size of 15-25 μm, and a third modified aluminum powder with a D50 particle size of 25-40 μm. The structure of the first modified aluminum powder, the second modified aluminum powder, and the third modified aluminum powder all includes a spherical aluminum core and a silicon dioxide layer covering the surface of the aluminum core. The surface of the silicon dioxide layer is grafted with a vinyl-containing silane coupling agent. The surface-hydroxylated tetraneedle zinc oxide is obtained by introducing hydroxyl groups onto its surface through alkaline solution treatment.

2. The organosilicon thermally conductive gel according to claim 1, characterized in that, The organosilicon thermal conductive gel, by weight, comprises 65-80 parts of terminal vinyl polydimethylsiloxane in the organosilicon matrix, 15-30 parts of side-chain hydrogen-containing polydimethylsiloxane, and 5-15 parts of branched vinyl silicone oil. In the thermally conductive filler system, the surface-modified spherical aluminum powder is 700-850 parts, and the surface-hydroxylated tetraneedle zinc oxide is 100-250 parts.

3. The organosilicon thermally conductive gel according to claim 1, characterized in that, The mass ratio of the first modified aluminum powder, the second modified aluminum powder, the third modified aluminum powder, and the tetraneedle-shaped zinc oxide is 1.8-2.2 : 2.8-3.3 : 3.6-4.2 : 0.8-1.

2.

4. The organosilicon thermally conductive gel according to claim 3, characterized in that, The length of a single needle in the tetra-needle zinc oxide is 1-10 μm.

5. The organosilicon thermally conductive gel according to claim 1, characterized in that, The catalyst is a platinum catalyst; And / or, the inhibitor is 1-ethynyl-1-cyclohexanol and diethyl maleate.

6. A method for preparing an organosilicon thermally conductive gel, characterized in that, The preparation of the organosilicon thermally conductive gel according to any one of claims 1-5 includes the following steps: S1: Surface-coating and grafting treatment is performed on spherical aluminum powder to obtain surface-modified spherical aluminum powder; hydroxylation treatment is performed on tetraneedle-shaped zinc oxide to obtain surface-hydroxylated tetraneedle-shaped zinc oxide. S2: The surface-hydroxylated tetrane needle-shaped zinc oxide is first mixed and dispersed with branched vinyl silicone oil to form a premixed network; S3: Add vinyl-terminated polydimethylsiloxane, inhibitor, and hydrogen-containing polydimethylsiloxane to the premixed network, and add surface-modified spherical aluminum powder in batches for a second mixing and dispersion. S4: Add catalyst, perform third mixing, dispersion and degassing to obtain the organosilicon thermal conductive gel.

7. The method for preparing the organosilicon thermally conductive gel according to claim 6, characterized in that, In step S2, the first mixing and dispersion temperature is 20-30℃, and the total dispersion time is 30-60 minutes.

8. The method for preparing the organosilicon thermally conductive gel according to claim 6, characterized in that, In step S3, the surface-modified spherical aluminum powder is added in at least two batches: first, the third modified aluminum powder is added, and then the first modified aluminum powder and the second modified aluminum powder are added. And / or, the second mixing dispersion includes alternating high-shear phases and low-shear phases, wherein the high-shear phase has an orbital speed of 15-25 rpm and a rotational speed of 50-70 rpm, lasting 1-3 minutes; the low-shear phase has an orbital speed of 3-8 rpm and a rotational speed of 8-15 rpm, lasting 2-4 minutes; and the high-shear phase and low-shear phase are alternated 4-6 times.

9. The method for preparing the organosilicon thermally conductive gel according to claim 6, characterized in that, In step S1, the surface coating and grafting treatment of the spherical aluminum powder includes: forming a silica coating layer on the surface of the spherical aluminum powder using the sol-gel method, and then grafting the silica coating layer onto the surface using a vinyl-containing silane coupling agent.

10. The method for preparing the organosilicon thermally conductive gel according to claim 6, characterized in that, In step S1, the hydroxylation treatment of tetraneedle zinc oxide includes: soaking the tetraneedle zinc oxide in an alkaline solution with a concentration of 1-3 wt%.

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