Composite heat-conducting silica gel applied to liquid cooling plate and preparation method thereof

Abstract

The application discloses a composite heat-conducting silica gel applied to a liquid cooling plate and a preparation method thereof, and relates to the technical field of high polymer compound compositions and organic silicon compounds.The composite heat-conducting silica gel applied to the liquid cooling plate comprises the following raw materials in parts by mass: an organic silicon rubber matrix 80-100 parts, a composite heat-conducting filler 40-60 parts, a flame retardant 3-8 parts, a crosslinking agent 2-5 parts, a catalyst 0.5-2 parts and an anti-aging agent 1-3 parts.Through the synergistic effect of the composite heat-conducting filler, a more efficient heat-conducting network is constructed, the performance bottleneck of a single filler system is broken, and the heat-conducting performance is obviously better than that of traditional heat-conducting silica gel.The composite heat-conducting silica gel applied to the liquid cooling plate guarantees the flame retardancy, processability and long-term stability, overcomes the contradiction of increased brittleness and increased viscosity caused by high filler filling, and realizes the unity of high heat conductivity and durability.

Description

Technical Field

[0001] This invention relates to the field of organosilicon compound technology, specifically to a composite thermally conductive silicone for use in liquid cooling plates and its preparation method. Background Technology

[0002] With the continuous improvement of electronic device performance and the rapid increase in integration, the heat generated by electronic components during operation is also increasing. Effective heat dissipation has become one of the key factors to ensure the stable operation of electronic devices. Liquid cooling plates, as a highly efficient heat dissipation component, are widely used in many fields such as new energy vehicles, 5G communication base stations, and industrial cooling systems. Thermally conductive silicone, as the core thermally conductive medium of the liquid cooling plate, directly affects the heat dissipation efficiency of the liquid cooling plate and the stability of electronic device operation.

[0003] Currently available thermally conductive silicone products face several pressing issues. Firstly, the use of a single thermally conductive filler limits further improvements in thermal conductivity. For instance, while using alumina as a filler can increase thermal conductivity, high filler concentrations can lead to a significant increase in material viscosity, making processing difficult and negatively impacting the mechanical properties of the matrix, such as making the material brittle and reducing its tensile strength and elongation at break, thus failing to meet the application requirements of liquid cooling plates under complex working conditions. Secondly, the high-temperature resistance and aging resistance of existing thermally conductive silicone products need improvement. In high-temperature environments, some thermally conductive silicone products exhibit performance degradation, with their thermal conductivity gradually decreasing over time. This is mainly due to the dissociation of the cross-linked structure within the material at high temperatures and the weakening of the interaction between the filler and the matrix. Furthermore, during long-term use, thermally conductive silicone is susceptible to aging caused by factors such as oxygen and ultraviolet radiation, manifesting as surface cracking and increased hardness. This not only affects its appearance but, more importantly, deteriorates its thermal conductivity and sealing performance, thereby impacting the service life and reliability of the liquid cooling plate and increasing the maintenance costs and failure risks of electronic equipment. Therefore, developing a composite thermally conductive silicone with excellent thermal conductivity, high temperature resistance, and aging resistance is of great practical significance for promoting the development of liquid cooling plate technology and improving the overall performance of electronic devices. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a composite thermally conductive silicone rubber for use in liquid cooling plates. This silicone rubber, through optimized formulation and preparation process, uses graphene fiber and alumina as composite thermally conductive fillers, combined with novel anti-aging agents, achieving high thermal conductivity, excellent high-temperature resistance, and anti-aging properties, effectively solving the performance deficiencies of traditional thermally conductive silicone rubber in liquid cooling plate applications.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a composite thermally conductive silicone rubber for use in liquid cooling plates, comprising the following raw materials in parts by weight: 80-100 parts of silicone rubber matrix, 40-60 parts of composite thermally conductive filler, 3-8 parts of flame retardant, 2-5 parts of crosslinking agent, 0.5-2 parts of catalyst, and 1-3 parts of anti-aging agent; The anti-aging agent has the structure shown in Formula 1: Formula 1; R1 is selected from: methyl, ethyl, propyl, tert-butyl, methoxy.

[0006] Furthermore, the silicone rubber matrix is ​​a mixture of vinyl silicone oil and hydrogen-based silicone oil, with a mass ratio of 3-5:1.

[0007] Furthermore, the composite thermally conductive filler is composed of graphene fiber and alumina in a mass ratio of 1:2-3.

[0008] Furthermore, the flame retardant is aluminum hydroxide.

[0009] Furthermore, the crosslinking agent is polydimethylsiloxane.

[0010] Furthermore, the catalyst is dibutyltin dilaurate.

[0011] Furthermore, the anti-aging agent is any one of the compounds shown in the following structures: .

[0012] A method for preparing composite thermally conductive silicone for use in liquid cooling plates includes the following steps: S1. Add the silicone rubber matrix, composite thermally conductive filler, flame retardant, and anti-aging agent to a mixing container and stir and mix them under a nitrogen atmosphere; S2. Add the crosslinking agent and catalyst, continue vacuum stirring until uniformly dispersed, and cure to obtain a composite thermally conductive silicone for use in liquid cooling plates.

[0013] Furthermore, the stirring speed is 800-1200 rpm, the mixing temperature is 60-80℃, and the mixing time is 1-2 hours.

[0014] Furthermore, the curing temperature is 120-150℃, and the curing time is 45-75 minutes.

[0015] The anti-aging agent described in this invention contains a large number of hydroxyl groups, which have a strong hydrogen-donating capacity and can actively combine with free radicals generated during the aging process. This free radical conjugation effect stabilizes it, preventing it from continuing to participate in chain reactions, thereby blocking the chain reaction of material oxidative degradation. The anti-aging agent can effectively inhibit free radical oxidation reactions caused by high temperature or ultraviolet radiation, delaying the molecular chain breakage of the silicone rubber matrix. The alkyl chain R1 has the effect of regulating compatibility and steric hindrance; short-chain alkyl groups such as methyl and ethyl enhance the compatibility between the anti-aging agent and the silicone rubber matrix, ensuring uniform dispersion.

[0016] The organosilicon rubber matrix described in this invention provides basic flexibility and reaction sites; hydrogen-based silicone oil, acting as a crosslinking agent, forms a three-dimensional network structure with vinyl silicone oil through a hydrosilylation reaction; a 3-5:1 mass ratio balances flowability (processability) and post-curing elasticity. Composite thermally conductive fillers enhance thermal conductivity, alumina fills the voids, and graphene fibers establish thermally conductive pathways. The flame retardant aluminum hydroxide decomposes and absorbs heat to form a flame-retardant barrier, and its particle surface complements the alumina / graphene, further reducing interfacial thermal resistance. A crosslinking agent (polydimethylsiloxane) + catalyst (dibutyltin dilaurate) catalyzes the hydrosilylation reaction, promoting curing; at a mixing temperature of 60-80℃, the catalyst delays the initiation time of the crosslinking reaction, ensuring uniform dispersion of the filler; during the curing stage (120-150℃), crosslinking is rapidly completed, preventing filler sedimentation.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. Significantly improved thermal conductivity: Through the synergistic effect of composite thermally conductive fillers, a more efficient thermally conductive network is constructed, breaking through the performance bottleneck of single filler systems, and making the thermal conductivity significantly better than that of traditional thermally conductive silicone.

[0018] 2. Enhanced high-temperature aging resistance: The new anti-aging agent effectively inhibits molecular chain breakage under high-temperature conditions, significantly slows down the rate of material performance degradation, and solves the problem of performance decline of traditional products after long-term high-temperature use.

[0019] 3. Comprehensive performance balance optimization: While ensuring flame retardancy (V-0 grade), processability and long-term stability, it overcomes the contradictions such as increased brittleness and viscosity caused by high filler content, and achieves a balance between high thermal conductivity and durability. Attached Figure Description

[0020] Figure 1 The anti-aging agent 1 described in this invention 1 HNMR image. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Synthesis example 1 Synthesis of Anti-aging Agent 1: ; Step 1: Under a nitrogen atmosphere, 20 g of raw material 1, 71.40 g of potassium phosphate trihydrate, 0.16 g of pyridine-2-carboxylic acid, 1.28 g of CuI, and 150 g of DMSO were added sequentially to the reaction system. The mixture was stirred until homogeneous, and then 120 g of DMSO solution containing 19.79 g of raw material 2 was slowly added dropwise. The mixture was stirred until homogeneous, and then heated to 85 °C for 16 h. After cooling, the reaction mixture was extracted with ammonia solution and methyl tert-butyl ether. The organic phase was washed five times with water and then twice with saturated NaCl solution. Finally, the combined organic phase was dried with anhydrous magnesium sulfate, filtered to retain the organic phase, evaporated to dryness, and subjected to silica gel column chromatography with a mixture of petroleum ether and ethyl acetate as eluent. The mixture was evaporated to dryness to obtain 21.13 g of intermediate 1.

[0023] Step 2: Under a nitrogen atmosphere, 21.13 g of intermediate 1, 32.49 g of raw material 3, 30.53 g of potassium carbonate, 3.03 g of tris(dibenzylacetone)palladium, 1.12 g of tri-tert-butylphosphine, and 250 g of toluene were added sequentially to the reaction system. The mixture was stirred until homogeneous, heated to 120 °C, and refluxed for 12 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered using diatomaceous earth. After the filtrate was cooled to room temperature, it was washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried using anhydrous magnesium sulfate. The organic phase was filtered and evaporated to dryness. The mixture was then subjected to silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as eluent. The solution was evaporated to dryness to obtain 31.25 g of anti-aging agent 1.

[0024] Product structure identification: MS(m / z) of intermediate 1: [M+H] + =192; MS (m / z) of anti-aging agent 1: [M+H] + =356; Anti-aging agent 1 1HNMR(CDCl3)=δ6.76(dd,1H),6.65(d,1H),6.45(m,1H),4.69(d,1H),4.43-4.30(m,1H),4.30-4.18(m,1H),4.13-4.03(m,1 H),4.03-3.85(m,4H),3.84-3.70(m,2H),3.65-3.50(m,5H),3.56-3.33(m,2H),2.79(m2H),1.99-1.74(m,4H),1.12(t,3H).

[0025] Synthesis Example 2-Synthesis Example 5 In Synthesis Examples 2-5, anti-aging agents 2 and 5 were synthesized sequentially, following the same synthesis method as in Synthesis Example 1, except that raw material 2 was replaced, while the rest remained the same as in Synthesis Example 1. The specific structures of raw material 2, anti-aging agents 2-5, and MS (m / z) data are shown in Table 1.

[0026] Table 1. Structures of raw material 2, anti-aging agent 2 to anti-aging agent 5, and MS (m / z) data involved in synthesis examples 2-5.

[0027]

[0028] Example 1 This embodiment provides a composite thermally conductive silicone rubber for use in liquid cooling plates, the raw material composition and mass parts of which are as follows: silicone rubber matrix: 90 parts (composed of vinyl silicone oil and hydrogen-based silicone oil in a mass ratio of 4:1), composite thermally conductive filler: 50 parts (composed of graphene fiber and alumina in a mass ratio of 1:2.5), flame retardant: 5 parts (aluminum hydroxide), crosslinking agent: 3 parts (polydimethylsiloxane), catalyst: 1 part (dibutyltin dilaurate), anti-aging agent: 2 parts (using anti-aging agent 1 obtained from synthesis example 1).

[0029] A method for preparing composite thermally conductive silicone for use in liquid cooling plates: S1. Place the silicone rubber matrix, composite thermally conductive filler, flame retardant, and anti-aging agent in a vacuum stirred reactor, purge the air with nitrogen to maintain a nitrogen atmosphere, and stir and mix at 1000 rpm for 1.5 hours at 70°C.

[0030] S2. Add crosslinking agent and catalyst to the reactor, maintain the temperature at 70°C and turn on the vacuum system (vacuum degree ≤ -0.095MPa), and continue stirring at 1000rpm for 30 minutes until the material is evenly dispersed to form a paste-like colloid; S3. Inject the obtained colloid into a mold and place it in a 135℃ oven to cure for 60 minutes to obtain a cured composite thermally conductive silicone for use in liquid cooling plates.

[0031] Examples 2-5 The preparation of a composite thermally conductive silicone for liquid cooling plates is carried out by referring to the preparation method of Example 1, except that the anti-aging agent is replaced in sequence with anti-aging agent 2-anti-aging agent 5 prepared in Synthesis Examples 2-5, and the rest is the same as in Example 1.

[0032] Comparative Example 1 The preparation of a composite thermally conductive silicone for use in liquid cooling plates is the same as in Example 1, except that the anti-aging agent is not added.

[0033] Comparative Example 2 The preparation of a composite thermally conductive silicone for use in liquid cooling plates is carried out by referring to the preparation method of Example 1, except that the mass fraction of the composite thermally conductive filler is replaced with 20 parts, and the rest remains the same as in Example 1.

[0034] Performance testing: 1. The thermal conductivity of a composite thermally conductive silicone rubber prepared for use in liquid cooling plates in the examples and comparative examples was tested according to ASTM D 5470 standard. The data are shown in Table 2.

[0035] 2. The flame retardancy rating of a composite thermally conductive silicone rubber prepared in the examples and comparative examples for use in liquid cooling plates was tested according to UL 94. The data are shown in Table 2.

[0036] 3. The tensile strength of a composite thermally conductive silicone prepared in the examples and comparative examples for use in liquid cooling plates was tested after aging at 150°C for 100 hours, in accordance with ASTM D 412 standard. The data are shown in Table 2.

[0037] Table 2. Performance tests of a composite thermally conductive silicone prepared for use in liquid cooling plates in the examples and comparative examples.

[0038]

[0039] The thermal conductivity of the examples was significantly higher than that of the comparative examples, demonstrating that the synergistic effect of the composite thermally conductive filler and the anti-aging agent can effectively construct a stable thermally conductive network. Comparative Example 1 showed reduced thermal conductivity due to decreased filler dispersibility, while Comparative Example 2 exhibited the weakest thermal conductivity due to incomplete thermal pathways. All samples achieved a flame retardancy rating of V-0, indicating that aluminum hydroxide flame retardant can exert a highly efficient flame retardant effect in different formulations, unaffected by the amount of anti-aging agent or filler. The tensile strength of the examples after high-temperature aging was significantly higher than that of the comparative examples, especially superior to Comparative Example 1 without anti-aging agent, highlighting the effect of the novel anti-aging agent in inhibiting molecular chain breakage.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite thermally conductive silicone rubber for use in liquid cooling plates, characterized in that, The raw materials include the following parts by weight: 80-100 parts of silicone rubber matrix, 40-60 parts of composite thermally conductive filler, 3-8 parts of flame retardant, 2-5 parts of polydimethylsiloxane, 0.5-2 parts of catalyst, and 1-3 parts of anti-aging agent; The anti-aging agent has the structure shown in Formula 1: Formula 1; R1 is selected from: methyl, ethyl, propyl, tert-butyl, methoxy; The catalyst is dibutyltin dilaurate; The silicone rubber matrix is ​​a mixture of vinyl silicone oil and hydrogen-based silicone oil, with a mass ratio of 3-5:

1. The composite thermally conductive filler is composed of graphene fiber and alumina in a mass ratio of 1:2-3; The flame retardant is aluminum hydroxide.

2. The composite thermally conductive silicone rubber for use in liquid cooling plates according to claim 1, characterized in that, The anti-aging agent is any one of the compounds shown in the following structures: 。 3. A method for preparing a composite thermally conductive silicone rubber for use in liquid cooling plates as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Add the silicone rubber matrix, composite thermally conductive filler, flame retardant, and anti-aging agent to a mixing container and stir and mix them under a nitrogen atmosphere; S2. Add the polydimethylsiloxane and catalyst, continue vacuum stirring until uniformly dispersed, and solidify to obtain a composite thermally conductive silicone for use in liquid cooling plates.

4. The method for preparing a composite thermally conductive silicone rubber for use in a liquid cooling plate according to claim 3, characterized in that, The stirring speed is 800-1200 rpm, the mixing temperature is 60-80℃, and the mixing time is 1-2 hours.

5. The method for preparing a composite thermally conductive silicone rubber for use in a liquid cooling plate according to claim 3, characterized in that, The curing temperature is 120-150℃, and the curing time is 45-75 minutes.

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