A thermally conductive gasket material and a method of making the same

Abstract

The present application relates to a kind of heat-conducting gasket materials and its preparation method, belong to the technical field of silicone rubber composite material.The component of the heat-conducting gasket material is: 27-33wt% micron alumina, 8-11wt% nanometer alumina, 5.5-8.2wt% crosslinking type modified graphene, 1.9-2.6wt% crosslinking agent, 2.5-3.3wt% structure control agent;0.45-0.52wt% catalyst and 0.02-0.03wt% inhibitor, the balance is methyl vinyl silicone rubber raw rubber;Crosslinking type modified graphene is modified by molecular level surface, on the nanometer scale, the construction of heat-conducting network and the keeping of matrix flexibility are coordinated, so that heat-conducting gasket has high thermal conductivity performance, still maintains good mechanical reliability, compression filling and long service life, provides an ideal interface material solution for the thermal management of high-power electronic equipment.

Description

Technical Field

[0001] This invention belongs to the field of silicone rubber composite material technology, specifically, it relates to a thermally conductive pad material and its preparation method. Background Technology

[0002] Thermal pads are thermal interface materials used to fill the air gap between heat-generating devices and heat sinks or metal bases. Their core function is to eliminate contact thermal resistance and improve heat conduction efficiency, thereby ensuring the stable operation of electronic components. Silicone rubber is the most commonly used base material for thermal pads due to its excellent compression resilience, electrical insulation, high and low temperature resistance, and chemical stability.

[0003] However, the thermal conductivity of silicone rubber itself is low, which cannot meet the heat dissipation requirements of high-power-density equipment. The industry commonly uses a high proportion of thermally conductive fillers (such as alumina, boron nitride, and zinc oxide) to improve its thermal conductivity. The mechanism is that when the filler content reaches the percolation threshold, a continuous heat conduction network is formed in the matrix.

[0004] However, high filler content brings significant drawbacks: First, the introduction of a large amount of rigid inorganic filler leads to hardening and elasticity deterioration of the composite material, making it difficult to fully fill the micro-interface under assembly pressure, thus increasing contact thermal resistance. Second, high filler content severely deteriorates the mechanical properties of the material, resulting in decreased tensile strength and elongation at break, and increased brittleness. Under long-term thermal cycling and mechanical stress, microcracks are easily generated inside the gasket, and it may peel off from the interface, destroying the established heat conduction pathways and leading to a decrease in heat dissipation performance.

[0005] Therefore, developing a thermally conductive pad material with good thermal conductivity while maintaining the inherent flexibility and reliability of the silicone rubber matrix has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a thermally conductive pad material and a method for preparing the same.

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

[0008] A thermal pad material, with the following specific components:

[0009] Micron-sized alumina 27-33 wt%;

[0010] Nano-sized alumina 8-11 wt%

[0011] Cross-linked modified graphene 5.5-8.2 wt%;

[0012] Crosslinking agent 1.9-2.6 wt%;

[0013] Structure control agent 2.5-3.3 wt%;

[0014] Catalyst 0.45-0.52 wt%;

[0015] Inhibitor 0.02-0.03 wt%;

[0016] The remainder is raw methyl vinyl silicone rubber.

[0017] Cross-linked modified graphene uses graphene oxide as a substrate. Its sheet planes are enriched with oxygen-containing groups, mainly hydroxyl groups, while the sheet edges are enriched with oxygen-containing groups, mainly carboxyl groups. Based on the difference in surface chemical activity of these sheets, the graphene oxide is sequentially modified by planar passivation and edge activation. The specific modification steps are as follows:

[0018] Step A1, planar passivation: Graphene oxide, 4-dimethylaminopyridine and anhydrous toluene are mixed and ultrasonically dispersed to form a uniform dispersion. Dry nitrogen is introduced for protection. 3-methylthiopropionyl chloride is slowly added at room temperature and the mixture is stirred for 30-40 min. Then the temperature is raised to 80-100℃ and the reaction continues for 4-5.5 h. Finally, the bottom precipitate is collected by centrifugation, washed with ethanol and dried to obtain planar passivated graphene.

[0019] Preferably, the average sheet diameter of graphene oxide is no higher than 40 μm, maintaining good dispersibility and facilitating the construction of effective thermally conductive structures in the composite system.

[0020] Furthermore, the feed ratio of graphene oxide, 3-methylthiopropionyl chloride, 4-dimethylaminopyridine and anhydrous toluene is controlled at 50g:15-22mmol:0.7-1g:360-420mL. 3-methylthiopropionyl chloride reacts with the hydroxyl groups on the plane of the graphene oxide sheet to esterify and graft 3-methylthiopropionyl chloride onto the surface of the graphene sheet.

[0021] Step A2, edge activation: Allyl isocyanate and anhydrous dimethylformamide are mixed under dry nitrogen protection, planar passivated graphene is added and ultrasonically dispersed, then dicyclohexylcarbodiimide is added, the temperature is raised to 65-75℃ and stirred for 8-10 hours, and finally the bottom precipitate is collected by centrifugation and washed with dimethylformamide and ethanol in sequence and dried to obtain cross-linked modified graphene.

[0022] Furthermore, the feed ratio of planar passivated graphene, allyl isocyanate, dicyclohexylcarbodiimide, and anhydrous dimethylformamide is controlled at 50g: 8-13mmol: 0.2-0.3g: 280-330mL. Allyl isocyanate reacts with the carboxyl groups at the edge of the planar passivated graphene sheets to introduce crosslinked allyl modification into the sheet edge, thereby activating the graphene sheet edge.

[0023] Preferably, the crosslinking agent is a hydrogen-containing silicone oil with a hydrogen content of not less than 0.1% and a room temperature viscosity of not more than 30 mm. 2 / s ensures that the crosslinking agent has high crosslinking activity and good dispersibility, which is conducive to the formation of uniform crosslinks.

[0024] Preferably, the structure control agent is a low molecular weight linear hydroxyl silicone oil, which effectively reduces the hardening of silicone rubber.

[0025] Preferably, the catalyst is a platinum preparation and the inhibitor is an ethynylcyclohexanol preparation, which synergistically and effectively regulates the vulcanization process of silicone rubber, which is conducive to uniform vulcanization and maintains the uniformity of gasket performance.

[0026] A method for preparing a thermally conductive pad material, specifically comprising:

[0027] Step S1, Mixing: Methyl vinyl silicone rubber raw rubber, structure control agent and cross-linked modified graphene are added in sequence and the temperature is controlled at 45-50℃ for initial mixing. Then, nano-sized alumina and micro-sized alumina, cross-linking agent, catalyst and inhibitor are added for final mixing. After vacuum degassing, the mixed rubber is obtained.

[0028] Step S2, Compression Molding: Inject the compounded rubber into the mold, and perform compression molding and vulcanization at 120-130℃ and 10-12MPa for 8-10 minutes. Demold to obtain the blank.

[0029] Step S3, Secondary vulcanization: Place the billet in a vulcanization kettle and vulcanize at 155-170℃ for 2.4-3 hours to obtain the thermally conductive pad material.

[0030] The beneficial effects of this invention are:

[0031] This invention

[0032] This invention cleverly resolves the inherent contradiction between high thermal conductivity and high elasticity by designing and synthesizing a cross-linked modified graphene with a special structure of "planar passivation and edge activation." This cross-linked modified graphene participates in the vulcanization and cross-linking reaction of silicone rubber using allyl groups at the edges of the sheets as active sites, forming a stable graphene-silicone rubber "geocell" network structure fixed by covalent bonds within the matrix. Because the sheet planes are passivated by the thioester structure, lateral cross-linking is avoided, allowing the large graphene sheets to maintain a high degree of freedom of movement in the composite system. This macroscopically endows the material with excellent compressive resilience and flexibility, ensuring that the gasket can fully fill the interfacial gaps under external force, effectively reducing contact thermal resistance.

[0033] More importantly, the thioether and ester groups in the thioester structure introduced in the planar structure can act as chelating groups, forming a stable chelating effect with alumina. This allows for the precise and secure enrichment of highly thermally conductive alumina particles on the surface and inside the "geocell" composed of graphene sheets. This structure microscopically constructs an efficient heat transfer channel between alumina and graphene, greatly improving the directional heat conduction efficiency and achieving high thermal conductivity with a relatively low total filler content.

[0034] Meanwhile, the covalently bonded geocell structure greatly enhances the interfacial bonding between the filler and the silicone rubber matrix, effectively suppressing the slippage and agglomeration of the filler under stress, as well as the microcracks caused by interfacial peeling during long-term thermal aging. This results in the thermally conductive pad prepared by this invention not only possessing high initial thermal conductivity and flexibility, but also excellent long-term reliability, maintaining stable performance under high and low temperature cycling and continuous pressure, thus extending its service life. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1: Preparation of thermally conductive pad material, as detailed below:

[0037] I. Preparation of Cross-linked Modified Graphene

[0038] Step A1, planar passivation: Take commercially available XFSG02 graphene oxide, with a calibrated sheet diameter range of 10-30 μm. Mix graphene oxide, 4-dimethylaminopyridine, and anhydrous toluene, add the mixture, and apply ultrasonic dispersion at 28 kHz for 30 min to form a uniform dispersion. Purge with dry nitrogen for protection, slowly add 3-methylthiopropionyl chloride at room temperature and stir for 30 min. Then raise the temperature to 100℃ and continue the reaction for 4 h. The feed ratio of graphene oxide, 3-methylthiopropionyl chloride, 4-dimethylaminopyridine, and anhydrous toluene is controlled at 50 g: 15 mmol: 0.7 g: 400 mL. Finally, centrifuge to collect the bottom precipitate, wash with ethanol, and dry to obtain planar passivated graphene.

[0039] Step A2, Edge Activation: Allyl isocyanate and anhydrous dimethylformamide were mixed under dry nitrogen protection, planar passivated graphene was added and ultrasonically dispersed at 28 kHz for 10 min, then dicyclohexylcarbodiimide was added, and the mixture was heated to 75 °C and stirred for 8 h. The feed ratio of planar passivated graphene, allyl isocyanate, dicyclohexylcarbodiimide and anhydrous dimethylformamide was controlled at 50 g: 8 mmol: 0.2 g: 320 mL. Finally, the bottom precipitate was collected by centrifugation and washed with dimethylformamide and ethanol in sequence, and then dried to obtain cross-linked modified graphene.

[0040] II. Preparation of Thermal Pad Materials

[0041] Before preparation, the raw materials are as follows, calculated by weight percentage:

[0042] 31 wt% micron-sized alumina, all made from ZT-L100G type raw materials, with a calibrated particle size range of 0.3-10 μm;

[0043] 8.5 wt% nano-sized alumina, all made from ZT-L30G type raw materials, with a calibrated particle size range of 30-50 nm;

[0044] 7.5 wt% cross-linked modified graphene, self-made by this institution;

[0045] The crosslinking agent is 1.9 wt%. In this example, RH-H45 type raw material is used, with a hydrogen content of approximately 0.12% and a room temperature viscosity of 20 mm. 2 / s;

[0046] The structure control agent, 3.1 wt%, is made of low molecular weight linear hydroxyl silicone oil of type PMX-0156.

[0047] The catalyst is 0.47 wt%, and all of them are PL-2 type platinum catalysts with a platinum content of 5000 ppm;

[0048] The inhibitors were 0.02 wt%, all of which were CX-5002 type ethynylcyclohexanol formulations;

[0049] The remainder is methyl vinyl silicone rubber raw material, all of which are 110-2 type general grade methyl vinyl silicone rubber raw material.

[0050] Step S1, Mixing: Methyl vinyl silicone rubber raw rubber, structure control agent and cross-linked modified graphene are added in sequence and the temperature is controlled at 50℃ for initial mixing for 14 min. Then, nano-sized alumina and micro-sized alumina, cross-linking agent, catalyst and inhibitor are added for final mixing for 37 min. After vacuum degassing for 20 min, the mixed rubber is obtained.

[0051] Step S2, Compression Molding: Inject the compounded rubber into the mold, and perform compression molding and vulcanization at 130℃ and 12MPa for 10 minutes to form the blank. Demold to obtain the blank.

[0052] Step S3, Secondary vulcanization: Place the billet in a vulcanization kettle and vulcanize at 170℃ for 3 hours to obtain the thermally conductive pad material.

[0053] Example 2: Preparation of thermally conductive pad material, as detailed below:

[0054] I. Preparation of Cross-linked Modified Graphene

[0055] Step A1, planar passivation: Take commercially available XFSG02 graphene oxide, with a calibrated sheet diameter range of 10-30 μm. Mix graphene oxide, 4-dimethylaminopyridine, and anhydrous toluene, add the mixture, and apply ultrasonic dispersion at 28 kHz for 30 min to form a uniform dispersion. Purge with dry nitrogen for protection, slowly add 3-methylthiopropionyl chloride at room temperature and stir for 32 min. Then raise the temperature to 95℃ and continue the reaction for 4.3 h. The feed ratio of graphene oxide, 3-methylthiopropionyl chloride, 4-dimethylaminopyridine, and anhydrous toluene is controlled at 50 g: 17 mmol: 0.8 g: 420 mL. Finally, centrifuge to collect the bottom precipitate, wash with ethanol, and dry to obtain planar passivated graphene.

[0056] Step A2, Edge Activation: Allyl isocyanate and anhydrous dimethylformamide were mixed under dry nitrogen protection, planar passivated graphene was added and ultrasonically dispersed at 28 kHz for 10 min, then dicyclohexylcarbodiimide was added, and the mixture was heated to 72 °C and stirred for 8.5 h. The feed ratio of planar passivated graphene, allyl isocyanate, dicyclohexylcarbodiimide and anhydrous dimethylformamide was controlled at 50 g: 10 mmol: 0.2 g: 330 mL. Finally, the bottom precipitate was collected by centrifugation and washed with dimethylformamide and ethanol in sequence, and then dried to obtain cross-linked modified graphene.

[0057] II. Preparation of Thermal Pad Materials

[0058] Before preparation, the raw materials are as follows, calculated by weight percentage:

[0059] Micron-sized alumina 33 wt%; nano-sized alumina 8 wt%; cross-linked modified graphene 8.2 wt%, self-made; cross-linking agent 2.2 wt%, this embodiment uses RH-H45 type raw material, hydrogen content approximately 0.12%, room temperature viscosity 20 mm. 2 / s; structure control agent 3.3wt%; catalyst 0.45wt%; inhibitor 0.02wt%; balance is methyl vinyl silicone rubber raw rubber.

[0060] Step S1, Mixing: Methyl vinyl silicone rubber raw rubber, structure control agent and cross-linked modified graphene are added in sequence and the temperature is controlled at 50℃ for initial mixing for 15 min. Then, nano-sized alumina and micro-sized alumina, cross-linking agent, catalyst and inhibitor are added for final mixing for 40 min. After vacuum degassing for 20 min, the mixed rubber is obtained.

[0061] Step S2, Compression Molding: Inject the compounded rubber into the mold, and perform compression molding and vulcanization at 130℃ and 12MPa for 10 minutes to form the blank. Demold to obtain the blank.

[0062] Step S3, Secondary vulcanization: Place the billet in a vulcanization kettle and vulcanize at 170℃ for 3 hours to obtain the thermally conductive pad material.

[0063] Example 3: Preparation of thermally conductive pad material, as detailed below:

[0064] I. Preparation of Cross-linked Modified Graphene

[0065] Step A1, planar passivation: Take commercially available XFSG01 graphene oxide, with a calibrated sheet diameter range of 3-10 μm. Mix graphene oxide, 4-dimethylaminopyridine, and anhydrous toluene and add them to the mixture. Disperse the mixture using ultrasonication at 33 kHz for 30 min to form a uniform dispersion. Purge with dry nitrogen for protection. Slowly add 3-methylthiopropionyl chloride at room temperature and stir for 30 min. Then raise the temperature to 85 °C and continue the reaction for 4 h. The ratio of graphene oxide, 3-methylthiopropionyl chloride, 4-dimethylaminopyridine, and anhydrous toluene is controlled at 50 g: 20 mmol: 0.9 g: 360 mL. Finally, centrifuge to collect the bottom precipitate, wash with ethanol, and dry to obtain planar passivated graphene.

[0066] Step A2, Edge Activation: Allyl isocyanate and anhydrous dimethylformamide were mixed under dry nitrogen protection, planar passivated graphene was added and ultrasonically dispersed at 33 kHz for 10 min, then dicyclohexylcarbodiimide was added, and the mixture was heated to 68 °C and stirred for 8 h. The feed ratio of planar passivated graphene, allyl isocyanate, dicyclohexylcarbodiimide and anhydrous dimethylformamide was controlled at 50 g: 12 mmol: 0.3 g: 280 mL. Finally, the bottom precipitate was collected by centrifugation and washed with dimethylformamide and ethanol in sequence, and then dried to obtain cross-linked modified graphene.

[0067] II. Preparation of Thermal Pad Materials

[0068] Before preparation, the raw materials are as follows, calculated by weight percentage:

[0069] Micron-sized alumina 27 wt%; nano-sized alumina 11 wt%; cross-linked modified graphene 5.5 wt%, self-made; cross-linking agent 2.6 wt%, this embodiment uses RH-H518 type raw material, hydrogen content approximately 0.18%, room temperature viscosity 10 mm. 2 / s; structure control agent 2.5wt%; catalyst 0.5wt%; inhibitor 0.03wt%; balance is methyl vinyl silicone rubber raw rubber.

[0070] Step S1, Mixing: Methyl vinyl silicone rubber raw rubber, structure control agent and cross-linked modified graphene are added in sequence and the temperature is controlled at 45℃ for initial mixing for 12 minutes. Then, nano-sized alumina and micro-sized alumina, cross-linking agent, catalyst and inhibitor are added for final mixing for 30 minutes. After vacuum degassing for 20 minutes, the mixed rubber is obtained.

[0071] Step S2, Compression Molding: Inject the compounded rubber into the mold, and perform compression molding and vulcanization at 120℃ and 10MPa for 8 minutes to form the blank. Demold to obtain the blank.

[0072] Step S3, Secondary vulcanization: Place the billet in a vulcanization kettle and vulcanize at 155℃ for 2.4 hours to obtain the thermally conductive pad material.

[0073] Example 4: Preparation of thermally conductive pad material, as detailed below:

[0074] I. Preparation of Cross-linked Modified Graphene

[0075] Step A1, planar passivation: Take commercially available XFSG01 graphene oxide, with a calibrated sheet diameter range of 3-10 μm. Mix graphene oxide, 4-dimethylaminopyridine, and anhydrous toluene and add them to the mixture. Disperse the mixture using ultrasonication at 33 kHz for 30 min to form a uniform dispersion. Purge with dry nitrogen for protection. Slowly add 3-methylthiopropionyl chloride at room temperature and stir for 35 min. Then raise the temperature to 80 °C and continue the reaction for 4.5 h. The ratio of graphene oxide, 3-methylthiopropionyl chloride, 4-dimethylaminopyridine, and anhydrous toluene is controlled at 50 g: 22 mmol: 1 g: 380 mL. Finally, centrifuge to collect the bottom precipitate, wash with ethanol, and dry to obtain planar passivated graphene.

[0076] Step A2, Edge Activation: Allyl isocyanate and anhydrous dimethylformamide were mixed under dry nitrogen protection, planar passivated graphene was added and ultrasonically dispersed at 33 kHz for 10 min, then dicyclohexylcarbodiimide was added, and the mixture was heated to 65 °C and stirred for 8.5 h. The feed ratio of planar passivated graphene, allyl isocyanate, dicyclohexylcarbodiimide and anhydrous dimethylformamide was controlled at 50 g: 13 mmol: 0.3 g: 290 mL. Finally, the bottom precipitate was collected by centrifugation and washed with dimethylformamide and ethanol in sequence, and then dried to obtain cross-linked modified graphene.

[0077] II. Preparation of Thermal Pad Materials

[0078] Before preparation, the raw materials are as follows, calculated by weight percentage:

[0079] Micron-sized alumina 28 wt%; nano-sized alumina 10 wt%; cross-linked modified graphene 6 wt%, prepared in-house; cross-linking agent 2.5 wt%, this embodiment uses RH-H518 type raw material, with a hydrogen content of approximately 0.18% and a room temperature viscosity of 10 mmHg. 2 / s; structure control agent 2.7wt%; catalyst 0.52wt%; inhibitor 0.03wt%; balance is methyl vinyl silicone rubber raw rubber.

[0080] Step S1, Mixing: Methyl vinyl silicone rubber raw rubber, structure control agent and cross-linked modified graphene are added in sequence and the temperature is controlled at 45℃ for initial mixing for 10 min. Then, nano-sized alumina and micro-sized alumina, cross-linking agent, catalyst and inhibitor are added for final mixing for 35 min. After vacuum degassing for 20 min, the mixed rubber is obtained.

[0081] Step S2, Compression Molding: Inject the compounded rubber into the mold, and perform compression molding and vulcanization at 120℃ and 11MPa for 9 minutes to form the blank. Demold to obtain the blank.

[0082] Step S3, Secondary vulcanization: Place the billet in a vulcanization kettle and vulcanize at 160℃ for 2.5h to obtain the thermally conductive pad material.

[0083] Comparative Example 1: This comparative example is a blank control. It follows the implementation method of Example 4, except that the cross-linked modified graphene is replaced with an equal amount of XFSG01 graphene oxide. The rest of the implementation process is exactly the same.

[0084] Comparative Example 2: Referring to Comparative Example 1, graphene oxide was coupled to prepare alkenyl graphene, which was then replaced in equal amounts. The preparation method of alkenyl graphene is as follows:

[0085] A 50% (v / v) ethanol aqueous solution was prepared, and silane coupling agent KH-570 was added and mixed. Hydrochloric acid was added to adjust the pH to 4, and the mixture was stirred and hydrolyzed for 30 min. Graphene oxide was then added and ultrasonically dispersed at 33 kHz to form a uniform dispersion. The mixture was then stirred for another 1 h. The feed ratio of graphene oxide, silane coupling agent KH-570, and ethanol aqueous solution was controlled at 50 g: 5.5 mL: 300 mL. Finally, the bottom precipitate was collected by centrifugation, washed with ethanol and water, and dried to obtain alkenyl graphene.

[0086] Samples were taken from the thermally conductive pad material prepared above, and tensile properties were tested according to ASTM D412-16 standard; springback tests were conducted according to ASTM D2632-15 standard; and creep was tested under ASTM D2990-17 conditions of 50℃, 0.2MPa, and 24h. Specific test results are shown in Table 1.

[0087] Table 1

[0088] Tensile strength / MPa Elongation at break / % Rebound rate / % Creep rate / % Example 1 3.57 242 81.9 4.7 Example 2 3.82 235 80.7 4.3 Example 3 3.19 282 85.1 5.5 Example 4 3.35 276 84.3 5.1 Comparative Example 1 2.48 209 72.6 8.4 Comparative Example 2 4.04 167 67.2 6.2

[0089] As shown in Table 1, the thermal pad material prepared in the examples exhibits good toughness, high resilience, and low creep, which helps to maintain the structural stability of the thermal pad.

[0090] Samples were taken from the thermally conductive pad material prepared above, and the thermal conductivity was tested according to ASTM D5470-17 standard. The samples were placed in a thermal aging chamber and cycled 500 times at a temperature of 25-100℃. The thermal conductivity was tested again and the rate of change was calculated. The specific test results are shown in Table 2.

[0091] Table 2

[0092] <![CDATA[Thermal conductivity / W·(m·K) -1 > thermal conductivity change rate / % Example 1 4.591 -5.18 Example 2 4.837 -5.54 Example 3 5.045 -4.62 Example 4 5.152 -4.05 Comparative Example 1 3.276 -13.82 Comparative Example 2 3.913 -9.26

[0093] As shown in Table 2, the thermal pad material prepared in the example has a high thermal conductivity, and under simulated heat dissipation cycle conditions, the rate of change of thermal conductivity is significantly lower than that of the comparative example, indicating excellent thermal stability.

[0094] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0095] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A thermally conductive pad material, characterized in that, The specific composition is as follows: 27-33 wt% micron-sized alumina, 8-11 wt% nano-sized alumina, 5.5-8.2 wt% cross-linked modified graphene, 1.9-2.6 wt% cross-linking agent, 2.5-3.3 wt% structure control agent; 0.45-0.52 wt% catalyst and 0.02-0.03 wt% inhibitor, with the balance being methyl vinyl silicone rubber raw rubber; The cross-linked modified graphene is prepared by the following steps: Step A1: Mix graphene oxide, 4-dimethylaminopyridine and anhydrous toluene and ultrasonically disperse them. Under dry nitrogen protection, slowly add 3-methylthiopropionyl chloride at room temperature and stir for 30-40 min. Then raise the temperature to 80-100℃ and continue the reaction for 4-5.5 h to prepare planar passivated graphene. Step A2: Allyl isocyanate and anhydrous dimethylformamide are mixed under dry nitrogen protection, planar passivated graphene is added and ultrasonically dispersed, then dicyclohexylcarbodiimide is added, and the mixture is heated to 65-75℃ and stirred for 8-10 hours to prepare cross-linked modified graphene.

2. The thermally conductive pad material according to claim 1, characterized in that, The feed ratio of graphene oxide, 3-methylthiopropionyl chloride, 4-dimethylaminopyridine and anhydrous toluene was controlled at 50g: 15-22mmol: 0.7-1g: 360-420mL.

3. The thermally conductive pad material according to claim 2, characterized in that, The average sheet diameter of graphene oxide is no higher than 40 μm.

4. The thermally conductive pad material according to claim 2, characterized in that, The feed ratio of planar passivated graphene, allyl isocyanate, dicyclohexylcarbodiimide and anhydrous dimethylformamide was controlled at 50g: 8-13mmol: 0.2-0.3g: 280-330mL.

5. The thermally conductive pad material according to claim 1, characterized in that, The crosslinking agent is a hydrogen-containing silicone oil with a hydrogen content of not less than 0.1% and a room temperature viscosity of not more than 30 mm. 2 / s.

6. The thermally conductive pad material according to claim 1, characterized in that, The structure control agent is a low molecular weight linear hydroxyl silicone oil.

7. The thermally conductive pad material according to claim 1, characterized in that, The catalyst is a platinum preparation, and the inhibitor is ethynylcyclohexanol.

8. A method for preparing a thermally conductive pad material according to any one of claims 1-7, characterized in that, Specifically: Step S1: Methyl vinyl silicone rubber raw rubber, structure control agent and cross-linked modified graphene are added in sequence and the temperature is controlled at 45-50℃ for initial mixing. Then, nano-sized alumina and micro-sized alumina, cross-linking agent, catalyst and inhibitor are added for final mixing. After vacuum degassing, the compound is obtained. Step S2: Inject the compounded rubber into the mold, and mold and vulcanize it at 120-130℃ and 10-12MPa for 8-10 minutes. Demold the mixture to obtain the blank. Step S3: Place the billet in a vulcanizing kettle and vulcanize at 155-170℃ for 2.4-3 hours to obtain the thermally conductive pad material.