A high-flexibility thermal conductive pad and preparation method thereof

Abstract

The present application relates to the field of thermal conductive material technology, and specifically discloses a high-flexibility thermally conductive pad and a preparation method thereof. A high-flexibility thermally conductive pad, in parts by weight, comprises raw materials including 23-46 parts of vinyl-terminated side-chain vinyl silicone oil, 9-15 parts of hydrogen-terminated silicone oil, 5-10 parts of vinyl MQ silicone resin, 11-17 parts of cross-linked fibers, 0.3-1.8 parts of platinum catalyst, 1-5 parts of cross-linking agent, 0.3-1.8 parts of inhibitor, and 58-89 parts of thermally conductive filler; the thermally conductive filler includes carbon nanotubes and core-shell aluminum ball fillers in a mass ratio of 1: (5-9). A high-flexibility thermally conductive pad of the present application can be used for thermal management in electronic packaging, and has excellent thermal conductivity and flexibility.

Description

Technical Field

[0001] The present application relates to the technical field of thermal conductive materials, and more specifically, to a highly flexible thermal conductive gasket and a preparation method thereof. Background Art

[0002] With the rapid development of electronic information technology and the continuous upgrading of modern high-end electronic products, electronic equipment is increasingly moving towards high integration and high power. This has also led to a significant increase in the heat flux density of electronic components and the heat generated by electronic equipment. Therefore, thermal management in electronic packaging has become a major concern for electronic components.

[0003] Thermal pads are materials that fill the air gap between a heat-generating device and a heat sink or metal base, providing a heat conduction path. They are widely used to dissipate heat from electronic devices such as mobile phones, computers, and servers. High-performance thermal pads must not only have excellent thermal conductivity but also possess good flexibility and compression resilience to cover and fill uneven surfaces.

[0004] In response to the above-mentioned related technologies, the inventors found that the common thermal gaskets on the market are mainly based on silicone as the base material, and are prepared through various processes after adding thermal conductive fillers. Some thermal gaskets have improved the thermal conductivity of the thermal gasket to a certain extent, but due to the large amount of thermal conductive filler added or the low compatibility between the choice of thermal conductive filler and other raw materials, the thermal gasket has poor flexibility and is difficult to adapt to surfaces with complex shapes, affecting the effect and efficiency of the thermal gasket in the heat conduction process. Some thermal gaskets have good flexibility, but low thermal conductivity and cannot meet the problem of efficient heat dissipation. Summary of the Invention

[0005] In order to improve the thermal conductivity of a thermally conductive gasket while ensuring that the thermally conductive gasket has excellent flexibility, the present application provides a highly flexible thermally conductive gasket and a preparation method thereof.

[0006] In a first aspect, the present application provides a highly flexible thermally conductive gasket, which adopts the following technical solution:

[0007] A highly flexible thermally conductive gasket, comprising, by weight, 23-46 parts of vinyl-terminated side-chain vinyl silicone oil, 9-15 parts of hydrogen-terminated silicone oil, 5-10 parts of vinyl MQ silicone resin, 11-17 parts of cross-linked fiber, 0.3-1.8 parts of platinum catalyst, 1-5 parts of cross-linking agent, 0.3-1.8 parts of inhibitor, and 58-89 parts of thermally conductive filler.

[0008] The thermal conductive filler comprises carbon nanotubes and core-shell aluminum ball fillers in a mass ratio of 1:(5-9).

[0009] The inventors found that the thermally conductive gaskets prepared by selecting vinyl-terminated side-chain vinyl silicone oil and hydrogen-terminated silicone oil have better flexibility. This may be because the structure of vinyl-terminated side-chain vinyl silicone oil contains siloxane segments and side-chain vinyl-containing segments, and when combined with hydrogen-terminated silicone oil, it can simultaneously achieve certain chain extension and cross-linking. In particular, the two segments in the vinyl silicone oil exist in block form, and the cross-linked structure generated after the reaction of the end group and the side group vinyl ensures a certain amount of free space for the linear segment. At the same time, the cross-linking points of the cross-linked segment are uniform and dense, which makes the thermally conductive gasket not only have the softness and elasticity of linear resin, but also the network structure obtained by cross-linking can better disperse stress when subjected to external force, and can quickly restore to its original shape when deformed by force. Therefore, the gasket prepared by cross-linking vinyl-terminated side-chain vinyl silicone oil and hydrogen-terminated silicone oil exhibits good flexibility and resilience.

[0010] The addition of cross-linked fibers further promotes the interaction between the silicone oil raw materials. The cross-linked fibers have excellent flexibility and elasticity, which can improve the flexibility and elasticity of the gasket. The inventors have found that in the cross-linking system of the present application, the effect of adding cross-linked fibers is particularly prominent. This may be because the cross-linked fibers are more freely dispersed in the above-mentioned molecular cross-linking network, and the cross-linked fibers can effectively fill the stresses in different directions when receiving stresses in different directions. When the thermal gasket is used to cover and fill the surface gaps of the heating device, it effectively disperses the stresses from different directions, preventing the gasket from breaking or deforming due to stress concentration, so that the thermal gasket can better fit the tiny gaps on the surface of the heating device.

[0011] Carbon nanotubes and core-shell aluminum spheres are both excellent thermally conductive fillers. Adding them to silicone oil effectively increases the viscosity of the mixed slurry. During the thermal pad molding process, the spherical aluminum filler can be evenly distributed between the carbon nanotubes. This not only improves the fluidity and dispersion of the thermal pad during molding, significantly reducing the problem of carbon nanotubes entangled and agglomerated in the liquid slurry, but also compresses the carbon nanotubes during molding, straightening any curved carbon nanotubes. This further enhances the one-dimensional directional alignment of the carbon nanotubes and forms a more effective heat conduction channel within the thermal pad, thereby further improving the thermal conductivity of the thermal pad.

[0012] Optionally, the core-shell aluminum ball filler is a core-shell structure of spherical aluminum powder wrapped by alumina, and the preparation method of the core-shell aluminum ball filler comprises the following steps:

[0013] Spherical aluminum powder is added to anhydrous ethanol and ultrasonicated, and then centrifuged, dried and ground to form pretreated aluminum balls; the pretreated aluminum balls are heated to 300-500° C. in an air atmosphere and calcined for 6-8 hours to form a dense aluminum oxide layer on the surface of the pretreated aluminum balls, which are then cooled to obtain the product.

[0014] By adopting this technical solution, aluminum metal possesses excellent thermal conductivity, while aluminum oxide not only has good thermal conductivity but also good electrical insulation. Through a self-passivation process, aluminum microspheres serve as the core skeleton, surrounded by a dense layer of aluminum oxide to form a core-shell aluminum sphere filler. This core-shell aluminum sphere filler combines the excellent thermal conductivity of aluminum metal with the electrical insulation properties of ceramic materials, resulting in a thermally conductive gasket with high thermal conductivity and improved electrical insulation, increasing electrical safety and broadening its application areas.

[0015] Optionally, the raw materials of the cross-linked fiber include 40-55 parts of polyethylene glycol, 15-25 parts of

[0016] Toluene diisocyanate, 0.2-0.6 parts of dibutyltin dilaurate and 5-10 parts of chain extender.

[0017] Optionally, the chain extender is an amino chain extender, and the amino chain extender is selected from any one or more combinations of 4,4'-methylene-bis(3-chloro-2,6-diethylaniline), ethylenediamine, dimethylthiotoluenediamine and triethylenetetramine.

[0018] By adopting the above technical solution and using amino chain extenders to extend the chain in water-based polyurethane, the flexibility and plasticity of the cross-linked fibers prepared from water-based polyurethane are enhanced, the interfacial bonding strength is improved, favorable conditions are provided for the efficient transfer of heat, and the interfacial thermal resistance is reduced. On the other hand, it can significantly increase the flexibility and activity of the molecular chain and improve the flexibility of the thermal conductive gasket.

[0019] Optionally, the method for preparing the cross-linked fiber comprises the following steps:

[0020] Mix polyethylene glycol and toluene diisocyanate, heat and stir at 80-100°C in an inert gas atmosphere, cool to 70-80°C, add an amino chain extender, continue stirring to perform chain extension and curing cross-linking reaction, and obtain a polyurethane prepolymer;

[0021] Pour the polyurethane prepolymer into deionized water and stir to obtain a polyurethane stock solution;

[0022] The polyurethane stock solution is matured and then dry-spun to obtain cross-linked fibers.

[0023] By adopting the above technical solution, the preparation of cross-linked fibers using waterborne polyurethane is more environmentally friendly. The resulting cross-linked structure can effectively restrict the movement of molecular chains, making the material more compact, reducing the volatilization of small molecules, reducing pores and channels, and reducing the release of volatile substances. This helps reduce the volatile organic compounds (VOCs) released by the thermal gasket during use, thereby reducing harm to the environment and human body. In addition, the introduction of polyethylene glycol segments can further improve the flexibility of the fiber, thereby improving the flexibility of the gasket.

[0024] Optionally, the cross-linking agent is silane coupling agent KH-560.

[0025] Optionally, the inhibitor is selected from acetylenic alcohol compounds or cyclic siloxane oligomers containing olefin groups.

[0026] In a second aspect, the present application provides a method for preparing a highly flexible thermally conductive gasket, which adopts the following technical solution: A method for preparing a highly flexible thermally conductive gasket, comprising the following steps:

[0027] The carbon nanotubes and core-shell aluminum ball fillers are mixed to form a thermal conductive filler, which is then mixed with vinyl-terminated side chain vinyl silicone oil, hydrogen-terminated silicone oil, vinyl MQ silicone resin, cross-linked fiber, a cross-linking agent and an inhibitor, stirred evenly, heated at 120-150° C., and vacuum-reagented for 6-8 hours to obtain a blend;

[0028] After cooling the blend to room temperature, add platinum catalyst, stir, vacuum and react for 10-15 minutes, and then perform hot vulcanization molding at 120-130°C to obtain the product.

[0029] Optionally, the carbon nanotubes are pretreated as follows before being mixed with the core-shell aluminum sphere filler:

[0030] The carbon nanotubes are placed in an acid solution and ultrasonicated at 60-80°C for 4-8 hours, and then washed, filtered, and dried to obtain acid-treated carbon nanotubes;

[0031] The acid-treated carbon nanotubes were added to an acetone solution and stirred evenly, and then epoxy resin was added and stirred continuously. The mixture was heated to 120-150°C and reacted for 2-3 hours. The pretreated carbon nanotubes were obtained after washing, filtering and drying. The mass ratio of the epoxy resin to the acid-treated carbon nanotubes was (80-120):1.

[0032] By adopting this technical solution, epoxy groups are introduced onto the surface of the carbon nanotubes. This chemical interaction between chemical bonds significantly increases the compatibility of the carbon nanotubes with silicone oil, silicone resin, and cross-linked fibers, forming a stronger interfacial bond with other raw materials. This creates a tighter structure within the gasket, reducing interfacial thermal resistance. Furthermore, the dispersion of the carbon nanotubes within the three-dimensional network formed within the thermally conductive gasket is further improved, significantly reducing the entanglement and agglomeration of the carbon nanotubes, further enhancing the thermal conductivity of the carbon nanotubes as a thermally conductive filler.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. This application uses end-vinyl side-chain vinyl silicone oil and end-hydrogen silicone oil to form a three-dimensional cross-linked structure, which cooperates with the cross-linked fiber to form a three-dimensional thermal conductive network inside the thermal gasket. It not only forms an efficient heat conduction channel inside the thermal gasket, but also maintains excellent flexibility and resilience. It can better disperse stress from different directions when subjected to external force, and can quickly restore its original shape when deformed by force. It can better fit with the protrusions and tiny gaps on the surface of electronic components at the microscopic level, reduce the presence of air, and further improve the heat conduction efficiency.

[0035] 2. In this application, core-shell aluminum ball fillers formed by carbon nanotubes and alumina wrapped metallic aluminum are used as thermal conductive fillers, which effectively improves the fluidity and dispersibility between the raw material mixed slurry during the preparation and molding process of the thermal conductive gasket, and significantly reduces the problem of carbon nanotubes entangled and agglomerated with each other in the liquid slurry. At the same time, the spherical core-shell aluminum ball fillers enhance the one-dimensional directional arrangement effect of the carbon nanotubes, forming a more efficient thermal conductive channel.

[0036] 3. The core-shell aluminum ball filler of the present application forms an aluminum oxide layer on the surface of the metal aluminum, combining the excellent thermal conductivity of the metal material and the electrical insulation performance of the ceramic material, so that the thermal conductive gasket has higher thermal conductivity while improving electrical insulation, ensuring electrical safety. DETAILED DESCRIPTION

[0037] The following examples further illustrate the present application in detail.

[0038] raw material

[0039] Unless otherwise specified, the raw materials used in the examples and comparative examples of this application are all commercially available products, specifically:

[0040] Vinyl-terminated side-chain vinyl silicone oil, selected from Shandong Dayi Chemical, DY-V421, with an average vinyl content of 0.05 mol / 100 g;

[0041] End-hydrogenated silicone oil, selected from Shandong Dayi Chemical, DY-H201, with a hydrogen content of 0.05%;

[0042] Vinyl MQ silicone resin, selected from Shandong Dayi Chemical, DY-VMQ101;

[0043] Polyethylene glycol, selected from Hangzhou Electrochemical Group Auxiliary Chemical Co., Ltd., PEG-400;

[0044] Toluene diisocyanate, obtained from Shanghai Yuanye Biotechnology Co., Ltd., T135411;

[0045] Dibutyltin dilaurate, selected from Jieshikai, KA728361;

[0046] Dimethylthiotoluenediamine, selected from Congzhong Chemical, 17005;

[0047] Platinum catalyst, selected from Xiyi Chemical, PT-2000;

[0048] 1-Alkynylcyclohexanol, selected from Shanghe Chemical Technology, CAS: 78-27-3;

[0049] Tetravinyltetramethylcyclotetrasiloxane, selected from Dixin Chemical, CAS: 2554-06-5;

[0050] The crosslinking agent is silane coupling agent KH-560, selected from Shanghe Chemical Technology;

[0051] Carbon nanotubes, 5-15 μm in length, 8-20 nm in diameter, analytical grade;

[0052] Spherical aluminum powder, purity ≥99.5%, average particle size 5μm;

[0053] Spherical alumina powder, purity ≥99.9%, average particle size 5μm;

[0054] Epoxy resin, selected from Haihong Chemical, E51E44.

[0055] Preparation of cross-linked fibers 1.1-1.5

[0056] Preparation Example 1.1

[0057] Cross-linked fibers, the raw materials and amounts are shown in Table 1, wherein the chain extender is an amino chain extender, dimethylthiotoluenediamine;

[0058] Table 1

[0059]

[0060] The method for preparing the cross-linked fiber comprises the following steps:

[0061] S1: Polyethylene glycol and toluene diisocyanate were mixed, heated and stirred at 80°C under a nitrogen atmosphere for 3 hours, cooled to 70°C, an amino chain extender was added, and stirring was continued for 1 hour to perform chain extension and curing cross-linking reaction to obtain a polyurethane prepolymer;

[0062] S2: Pour the polyurethane prepolymer into 150 mL of deionized water and stir at 8000 rpm in a high-speed stirrer for 1 h to obtain a polyurethane stock solution;

[0063] S3: The polyurethane stock solution is matured, and then dry-spinned to obtain cross-linked fibers.

[0064] Preparation Example 1.2

[0065] The cross-linked fiber differs from that in Preparation Example 1.1 in that the raw materials and amounts are as shown in Table 1. The preparation method thereof comprises the following steps:

[0066] S1: Polyethylene glycol and toluene diisocyanate were mixed, heated and stirred at 100°C under a nitrogen atmosphere for 2 h, cooled to 80°C, and an amino chain extender was added. The mixture was stirred for 1 h to perform chain extension and curing cross-linking reaction to obtain a polyurethane prepolymer;

[0067] S2: Pour the polyurethane prepolymer into 150 mL of deionized water and stir at 8000 rpm in a high-speed stirrer for 1 h to obtain a polyurethane stock solution;

[0068] S3: The polyurethane stock solution is matured, and after maturation, dry spinning is performed to obtain cross-linked fibers.

[0069] Preparation Example 1.3

[0070] The cross-linked fiber differs from that in Preparation Example 1.1 in that the raw materials and amounts are as shown in Table 1. The preparation method thereof comprises the following steps:

[0071] S1: Polyethylene glycol and toluene diisocyanate were mixed, heated and stirred at 100°C in a N2 atmosphere for 2.5 hours, cooled to 70°C, and an amino chain extender was added. The mixture was stirred for 1 hour to perform chain extension and curing cross-linking reaction to obtain a polyurethane prepolymer;

[0072] S2: Pour the polyurethane prepolymer into 150 mL of deionized water and stir at 8000 rpm in a high-speed stirrer for 1 h to obtain a polyurethane stock solution;

[0073] S3: The polyurethane stock solution is matured, and after maturation, dry spinning is performed to obtain cross-linked fibers.

[0074] Preparation Example 1.4

[0075] The cross-linked fiber differs from that in Preparation Example 1.1 in that the raw materials and amounts are as shown in Table 1. The preparation method thereof comprises the following steps:

[0076] S1: Polyethylene glycol and toluene diisocyanate were mixed, heated and stirred at 90°C under a nitrogen atmosphere for 2 h, cooled to 80°C, an amino chain extender was added, and stirring was continued for 1 h to perform chain extension and curing cross-linking reaction to obtain a polyurethane prepolymer;

[0077] S2: Pour the polyurethane prepolymer into 150 mL of deionized water and stir at 8000 rpm in a high-speed stirrer for 1 h to obtain a polyurethane stock solution;

[0078] S3: The polyurethane stock solution is matured, and after maturation, dry spinning is performed to obtain cross-linked fibers.

[0079] Preparation Example 1.5

[0080] The cross-linked fiber is different from the preparation example 1.1 in that the chain extender in the raw material is 1,4-butanediol, and the other steps are the same as those in the preparation example 1.1.

[0081] Preparation Examples 2.1-2.3 of Core-Shell Aluminum Ball Fillers

[0082] Preparation Example 2.1

[0083] The core-shell aluminum ball filler is a core-shell structure of spherical aluminum powder wrapped by alumina. The average particle size of the spherical aluminum powder is 5 μm. The preparation method includes the following steps:

[0084] S1: Spherical aluminum powder was added to anhydrous ethanol and completely dispersed, ultrasonicated for 48 h, centrifuged at 3500 rpm for 30 min, dried for 4 h, and then ground to form pretreated aluminum balls;

[0085] S2: The pretreated aluminum ball is placed in a ceramic crucible under air atmosphere, heated to 300°C and calcined for 8 hours to form a dense aluminum oxide layer on the surface of the pretreated aluminum ball. After cooling, the thickness of the aluminum oxide layer is 9 nm.

[0086] Preparation Example 2.2

[0087] The core-shell aluminum ball filler is different from that in Preparation Example 2.1 in that its preparation method includes the following steps:

[0088] S1: Spherical aluminum powder was added to anhydrous ethanol and completely dispersed, ultrasonicated for 48 h, centrifuged at 3500 rpm for 30 min, dried for 4 h, and then ground to form pretreated aluminum balls;

[0089] S2: The pretreated aluminum ball is placed in a ceramic crucible under air atmosphere, heated to 400°C and calcined for 7 hours to form a dense aluminum oxide layer on the surface of the pretreated aluminum ball. After cooling, the aluminum oxide layer is obtained with a thickness of 7 nm.

[0090] Preparation Example 2.3

[0091] The core-shell aluminum ball filler is different from that in Preparation Example 2.1 in that its preparation method includes the following steps:

[0092] S1: Spherical aluminum powder was added to anhydrous ethanol and completely dispersed, ultrasonicated for 48 h, centrifuged at 3500 rpm for 30 min, dried for 4 h, and then ground to form pretreated aluminum balls;

[0093] S2: The pretreated aluminum ball is placed in a ceramic crucible under air atmosphere, heated to 500°C and calcined for 6 hours to form a dense aluminum oxide layer on the surface of the pretreated aluminum ball. After cooling, the thickness of the aluminum oxide layer is 5 nm.

[0094] Example

[0095] Example 1

[0096] A highly flexible thermally conductive gasket, the amounts of the raw materials used are shown in Table 2, wherein the cross-linked fibers are obtained by Preparation Example 1.1; the thermally conductive filler is carbon nanotubes and core-shell aluminum sphere filler in a mass ratio of 1:5, and the core-shell aluminum sphere filler is obtained by Preparation Example 2.1; and the inhibitor is an alkynol compound, 1-alkynylcyclohexanol.

[0097] Table 2

[0098]

[0099] The above-mentioned method for preparing a highly flexible thermally conductive gasket comprises the following steps:

[0100] S1: carbon nanotubes and core-shell aluminum sphere fillers are mixed to form a thermally conductive filler, which is then mixed with vinyl-terminated side-chain vinyl silicone oil, hydrogen-terminated silicone oil, vinyl MQ silicone resin, cross-linked fiber, a cross-linking agent, and an inhibitor. The mixture is stirred evenly, heated at 120°C, evacuated to a vacuum degree of -0.1 MPa, and reacted for 8 hours to obtain a blend.

[0101] S2: After cooling the blend to room temperature, add platinum catalyst, stir, evacuate to a vacuum degree of -0.1 MPa, react for 15 minutes, and then perform hot vulcanization molding on a flat vulcanizer at 10 MPa and 130°C to obtain the product.

[0102] Example 2

[0103] A highly flexible thermally conductive gasket, which differs from Example 1 in that the amounts of the raw materials are as shown in Table 2, wherein the cross-linked fibers are obtained from Preparation Example 1.2; the thermally conductive filler is carbon nanotubes and core-shell aluminum sphere fillers in a mass ratio of 1:7; and the inhibitor is an olefin-containing cyclic siloxane oligomer, tetravinyltetramethylcyclotetrasiloxane.

[0104] The above-mentioned method for preparing a highly flexible thermally conductive gasket comprises the following steps:

[0105] S1: carbon nanotubes and core-shell aluminum sphere fillers are mixed to form a thermally conductive filler, which is then mixed with vinyl-terminated side-chain vinyl silicone oil, hydrogen-terminated silicone oil, vinyl MQ silicone resin, cross-linked fiber, a cross-linking agent, and an inhibitor. The mixture is stirred evenly, heated at 140°C, evacuated to a vacuum degree of -0.1 MPa, and reacted for 6 hours to obtain a blend.

[0106] S2: After cooling the blend to room temperature, add platinum catalyst, stir, evacuate to a vacuum degree of -0.1 MPa, react for 15 minutes, and then perform hot vulcanization molding on a flat vulcanizer at 10 MPa and 120°C to obtain the product.

[0107] Example 3

[0108] A highly flexible thermally conductive gasket, which differs from Example 1 in that the amounts of the raw materials are as shown in Table 2, wherein the cross-linked fibers are obtained from Preparation Example 1.3; the thermally conductive filler is a carbon nanotube and a core-shell aluminum sphere filler in a mass ratio of 1:9;

[0109] The above-mentioned method for preparing a highly flexible thermally conductive gasket comprises the following steps:

[0110] S1: carbon nanotubes and core-shell aluminum sphere fillers are mixed to form a thermally conductive filler, which is then mixed with vinyl-terminated side-chain vinyl silicone oil, hydrogen-terminated silicone oil, vinyl MQ silicone resin, cross-linked fiber, a cross-linking agent, and an inhibitor. The mixture is stirred evenly, heated at 150°C, evacuated to a vacuum degree of -0.1 MPa, and reacted for 6 hours to obtain a blend.

[0111] S2: After cooling the blend to room temperature, add platinum catalyst, stir, evacuate to a vacuum degree of -0.1 MPa, react for 10 minutes, and then perform hot vulcanization molding on a flat vulcanizer at 10 MPa and 130°C to obtain the product.

[0112] Example 4

[0113] A highly flexible thermally conductive gasket, which differs from Example 1 in that the amounts of the raw materials are as shown in Table 2, wherein the cross-linked fibers are obtained from Preparation Example 1.4; the thermally conductive filler is a carbon nanotube and a core-shell aluminum sphere filler in a mass ratio of 1:6;

[0114] The above-mentioned method for preparing a highly flexible thermally conductive gasket comprises the following steps:

[0115] S1: carbon nanotubes and core-shell aluminum sphere fillers are mixed to form a thermally conductive filler, which is then mixed with vinyl-terminated side-chain vinyl silicone oil, hydrogen-terminated silicone oil, vinyl MQ silicone resin, cross-linked fiber, a cross-linking agent, and an inhibitor. The mixture is stirred evenly, heated at 150°C, evacuated to a vacuum degree of -0.1 MPa, and reacted for 7 hours to obtain a blend.

[0116] S2: After cooling the blend to room temperature, add platinum catalyst, stir, evacuate to a vacuum degree of -0.1 MPa, react for 15 minutes, and then perform hot vulcanization molding on a flat vulcanizer at 10 MPa and 120°C to obtain the product.

[0117] Example 5

[0118] A highly flexible thermally conductive gasket, which differs from Example 1 in that the cross-linked fibers in the raw materials are obtained from Preparation Example 1.5, and the other steps are the same as Example 1.

[0119] Example 6

[0120] A highly flexible thermally conductive gasket is different from Example 1 in that the core-shell aluminum ball filler in the raw material is obtained from Preparation Example 2.2, and the other steps are the same as Example 1.

[0121] Example 7

[0122] A highly flexible thermally conductive gasket, which differs from Example 1 in that the core-shell aluminum ball filler in the raw material is obtained from Preparation Example 2.3, and the other steps are the same as Example 1.

[0123] Example 8

[0124] A highly flexible thermally conductive gasket is different from Example 1 in that the core-shell aluminum ball filler in the raw material is spherical aluminum oxide powder, and the other steps are the same as Example 1.

[0125] Example 9

[0126] A highly flexible thermally conductive gasket is different from Example 1 in that the core-shell aluminum ball filler in the raw material is spherical metal aluminum powder, and the other steps are the same as Example 1.

[0127] Example 10

[0128] A highly flexible thermally conductive gasket is different from Example 1 in that the core-shell aluminum ball filler in the raw materials is spherical metal aluminum powder and spherical metal aluminum powder in a mass ratio of 1:3, and the other steps are the same as Example 1.

[0129] Example 11

[0130] A highly flexible thermally conductive gasket, which differs from Example 1 in that the carbon nanotubes are pretreated as follows before being mixed with the core-shell aluminum ball filler:

[0131] S1: placing carbon nanotubes in a mixed acid solution of H2SO4 / HNO3 with a volume ratio of 3:1, ultrasonicating at 60°C for 8 hours, and then washing, filtering, and drying to obtain acid-treated carbon nanotubes;

[0132] S2: Add the acid-treated carbon nanotubes to the acetone solution, stir evenly, then add the epoxy resin, continue stirring, and then heat to 120°C for reaction for 3 hours. After washing, filtering, and drying, the pretreated carbon nanotubes are obtained. The mass ratio of the added amount of the epoxy resin to the acid-treated carbon nanotubes is 12:1. The other steps are the same as in Example 1.

[0133] Example 12

[0134] A highly flexible thermally conductive gasket, which differs from Example 1 in that the carbon nanotubes are pretreated as follows before being mixed with the core-shell aluminum ball filler:

[0135] S1: placing carbon nanotubes in a mixed acid solution of H2SO4 / HNO3 with a volume ratio of 3:1, ultrasonicating at 80°C for 4 hours, and then washing, filtering, and drying to obtain acid-treated carbon nanotubes;

[0136] S2: Add the acid-treated carbon nanotubes to the acetone solution, stir evenly, then add the epoxy resin, continue stirring, and then heat to 150°C for reaction for 2 hours. After washing, filtering, and drying, the pretreated carbon nanotubes are obtained. The mass ratio of the added amount of the epoxy resin to the acid-treated carbon nanotubes is 8:1. The other steps are the same as in Example 1.

[0137] Comparative Example

[0138] Comparative Example 1

[0139] A highly flexible thermally conductive gasket is different from Example 1 in that the thermally conductive filler is only a core-shell aluminum ball filler and no carbon nanotubes are added. Other steps are the same as Example 1.

[0140] Comparative Example 2

[0141] A highly flexible thermally conductive gasket is different from Example 1 in that the thermally conductive filler is only carbon nanotubes and no core-shell aluminum ball filler is added. Other steps are the same as Example 1.

[0142] Comparative Example 3

[0143] A highly flexible thermally conductive gasket differs from Example 1 in that no cross-linked fiber is added, the cross-linked fiber in the raw material is replaced with vinyl MQ silicone resin of equal mass, and the other steps are the same as Example 1.

[0144] Comparative Example 4

[0145] A highly flexible thermally conductive gasket is prepared, which differs from Example 1 in that the vinyl-terminated side-chain vinyl silicone oil in the raw material is replaced with side-chain vinyl silicone oil DY-V411 of equal mass, and the other steps are the same as Example 1.

[0146] Comparative Example 5

[0147] A highly flexible thermally conductive gasket, which differs from Example 1 in that the end vinyl side chain vinyl silicone oil in the raw material is replaced by an equal mass of side chain vinyl silicone oil DY-V411, no cross-linked fiber is added, and the cross-linked fiber in the raw material is replaced by an equal mass of vinyl MQ silicone resin, and the other steps are the same as Example 1.

[0148] Performance testing

[0149] The high-flexibility thermally conductive gaskets obtained in Examples 1-12 and Comparative Examples 1-5 were subjected to thermal conductivity, flexibility and other related performance tests. Each test was performed 3 times, and the average value of the 3 times was taken as the final result. The test results are recorded in Table 3.

[0150] 1. Thermal conductivity: Test the thermal conductivity of the thermal pad according to ASTM D 5470 standard;

[0151] 2. Compression resilience: The spring rate of the thermal pad is tested according to ASTM D 575-91.

[0152] 3. Hardness: Use Shore hardness tester to test the hardness of thermal pad according to AM type;

[0153] 4. Tensile strength: The tensile strength of the thermal pad is tested according to ASTM D 412 standard;

[0154] 5. Electrical insulation performance: The breakdown voltage of the thermal pad is tested according to ASTM D 149.

[0155] Table 3

[0156]

[0157]

[0158] According to the performance test results in Table 3, it can be seen that the thermal conductivity of the high-flexibility thermal conductive pad of the present application is 8.63-11.53 W·(m·K) -1, Shore hardness is 28-38HA, compression rebound rate is 74-91%, tensile strength is 1.13-1.74MPa, and breakdown voltage is 1.07-1.86Kv / mm. This shows that the high-flexibility thermal conductive gasket of the present application has excellent thermal conductivity and electrical insulation, and at the same time has good flexibility and compression rebound resilience, which can meet the needs of the thermal conductive gasket to better fit the surface of some uneven electronic components and efficiently transfer and dissipate heat.

[0159] According to the performance test results of Examples 1-5 and Comparative Example 3, it can be seen that the addition of cross-linked fibers further promotes the interaction between the silicone oil raw materials, which not only enhances the overall strength of the thermal gasket, but also significantly enhances the flexibility of the heating gasket, so that the thermal gasket can effectively disperse stress and prevent the gasket from breaking or deforming due to stress concentration.

[0160] According to the performance test results of Examples 1-4, Examples 6-10 and Comparative Example 2, it can be seen that during the molding process of the thermal gasket, the spherical aluminum filler can be evenly distributed between the carbon nanotubes, so that the thermal gasket has better fluidity and dispersibility during the molding process, significantly reducing the problem of carbon nanotubes entangled and agglomerated with each other in the liquid slurry, reducing the interfacial thermal resistance, and at the same time enhancing the one-dimensional directional arrangement effect of the carbon nanotubes, forming a more effective heat conduction channel inside the thermal gasket, thereby further improving the thermal conduction efficiency of the thermal gasket.

[0161] Through self-passivation, metal aluminum microspheres are used as the core skeleton and wrapped with a dense aluminum oxide layer to form a core-shell aluminum ball filler. It combines the excellent thermal conductivity of metal aluminum with the electrical insulation properties of ceramic materials, so that the thermal conductive gasket has higher thermal conductivity while improving electrical insulation, increasing electrical safety and broadening the application field of thermal conductive gaskets.

[0162] According to the performance test results of Examples 1-4, Examples 11-12 and Comparative Example 1, it can be seen that the carbon nanotubes rely on their special one-dimensional linear structure to establish an efficient heat conduction channel network inside the thermal gasket, significantly improving the thermal conductivity efficiency of the thermal gasket.

[0163] The introduction of epoxy groups onto the surface of carbon nanotubes significantly increases the compatibility of carbon nanotubes with silicone oil, silicone resin, and cross-linked fibers through chemical interactions between chemical bonds, reducing interfacial thermal resistance. Simultaneously, the dispersion of the carbon nanotubes within the three-dimensional network structure formed within the thermal pad is further improved, significantly reducing the entanglement and agglomeration of the carbon nanotubes. This further enhances the thermal conductivity of the carbon nanotubes as a thermally conductive filler, as well as the thermal pad's mechanical properties, such as flexibility.

[0164] According to the performance test results of Example 1 and Comparative Examples 3-5, it can be seen that the cross-linking of the vinyl-terminated side-chain vinyl silicone oil and the hydrogen-terminated silicone oil selected in this application effectively improves the toughness of the gasket compared with the side-chain vinyl silicone oil, especially the addition of cross-linked fibers to the network structure formed by the vinyl-terminated side-chain vinyl silicone oil DY-V421. Compared with the vinyl silicone oil DY-V411, the cross-linked fibers have a better effect on improving flexibility and elasticity.

[0165] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A highly flexible thermally conductive pad, characterized in that: The raw materials include, by weight, 23-46 parts of vinyl-terminated side-chain vinyl silicone oil, 9-15 parts of hydrogen-terminated silicone oil, 5-10 parts of vinyl MQ silicone resin, 11-17 parts of cross-linked fiber, 0.3-1.8 parts of platinum catalyst, 1-5 parts of cross-linking agent, 0.3-1.8 parts of inhibitor and 58-89 parts of thermal conductive filler; the thermal conductive filler includes carbon nanotubes and core-shell aluminum sphere fillers in a mass ratio of 1:(5-9); The raw materials of the cross-linked fiber include 40-55 parts of polyethylene glycol, 15-25 parts of toluene diisocyanate, 0.2-0.6 parts of dibutyltin dilaurate and 5-10 parts of chain extender; The core-shell aluminum ball filler is a core-shell structure in which spherical metal aluminum powder is wrapped by alumina. The preparation method of the core-shell aluminum ball filler comprises the following steps: Spherical aluminum powder is added to anhydrous ethanol and ultrasonicated, and then centrifuged, dried and ground to form pretreated aluminum balls; the pretreated aluminum balls are heated to 300-500° C. in an air atmosphere and calcined for 6-8 hours to form a dense aluminum oxide layer on the surface of the pretreated aluminum balls, which are then cooled to obtain the product.

2. The high-flexibility thermally conductive pad according to claim 1, characterized in that: The chain extender is an amino chain extender, and the amino chain extender is selected from any one or more combinations of 4,4'-methylene-bis(3-chloro-2,6-diethylaniline), ethylenediamine, dimethylthiotoluenediamine and triethylenetetramine.

3. The high-flexibility thermally conductive pad according to claim 2, characterized in that: The preparation method of the cross-linked fiber comprises the following steps: Mix polyethylene glycol and toluene diisocyanate, heat and stir at 80-100°C in an inert gas atmosphere, cool to 70-80°C, add an amino chain extender, continue stirring to perform chain extension and curing cross-linking reaction, and obtain a polyurethane prepolymer; Pour the polyurethane prepolymer into deionized water and stir to obtain a polyurethane stock solution; The polyurethane stock solution is matured and then dry-spun to obtain cross-linked fibers.

4. The high-flexibility thermally conductive pad according to claim 1, characterized in that: The cross-linking agent is silane coupling agent KH-560.

5. The high-flexibility thermally conductive pad according to claim 1, characterized in that: The inhibitor is an alkynol compound or a cyclic siloxane oligomer containing an olefin group.

6. The method for preparing a highly flexible thermally conductive gasket according to any one of claims 1 to 5, characterized in that: The following steps are involved: The carbon nanotubes and core-shell aluminum ball fillers are mixed to form a thermal conductive filler, which is then mixed with vinyl-terminated side chain vinyl silicone oil, hydrogen-terminated silicone oil, vinyl MQ silicone resin, cross-linked fiber, a cross-linking agent and an inhibitor, stirred evenly, heated at 120-150° C., and vacuum-reagented for 6-8 hours to obtain a blend; After cooling the blend to room temperature, add platinum catalyst, stir, vacuum and react for 10-15 minutes, and then perform hot vulcanization molding at 120-130°C to obtain the product.

7. The method for preparing a highly flexible thermally conductive gasket according to claim 6, wherein: The carbon nanotubes are pretreated as follows before being mixed with the core-shell aluminum sphere filler: The carbon nanotubes are placed in an acid solution and ultrasonicated at 60-80°C for 4-8 hours, and then washed, filtered, and dried to obtain acid-treated carbon nanotubes; The acid-treated carbon nanotubes are added to an acetone solution and stirred evenly, and then epoxy resin is added and stirred continuously. The mixture is then heated to 120-150°C and reacted for 2-3 hours. The pretreated carbon nanotubes are obtained after washing, filtering and drying. The mass ratio of the epoxy resin to the acid-treated carbon nanotubes is (8-12):1.

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