Liquid metal composite gasket and preparation method thereof

Abstract

The invention discloses a liquid metal composite gasket and a preparation method thereof. By combining a composite spinning technology and a composite material preparation process, interface bonding between liquid metal and a polyurethane matrix is optimized, and a continuous heat conduction channel is constructed, so that the heat conduction efficiency and the rebound effect of the material are remarkably improved. According to the obtained composite gasket, the thermal resistance is smaller than or equal to 0.06 DEG C cm / W at 40Psi, the density is smaller than 1.2 g / cc, the rebound resilience is larger than or equal to 60%, the tensile strength is larger than 0.05 MPa, the compression ratio is larger than 40% at 40Psi, the compression stress is smaller than or equal to 65 Psi at 50% / 10 min, and the creep property is smaller than or equal to 1 mm.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional gasket preparation, and specifically relates to a liquid metal composite gasket and a preparation method thereof. BACKGROUND

[0002] With the development of electronic devices towards high performance and miniaturization, efficient management of heat has become a key technical problem. Traditional heat-conducting gaskets are mostly filled with heat-conducting fillers (such as alumina, boron nitride, etc.) in silicone rubber or polymer matrix, but their heat-conducting performance is limited, and there are problems such as high interfacial thermal resistance and poor resilience. In recent years, liquid metal has attracted widespread attention due to its excellent heat conductivity and good flexibility, but how to uniformly distribute it in the polymer matrix and build an efficient heat-conducting channel is still a technical difficulty.

[0003] Existing patents mainly focus on simple physical mixing or coating methods in the preparation of liquid metal composites, which is difficult to effectively control the microstructure, resulting in limited improvement of heat-conducting performance and significant decrease of mechanical performance. Therefore, it is urgent to develop a new type of composite gasket and an efficient preparation process to meet the dual demands of heat-conducting performance and mechanical performance for high-end applications. SUMMARY

[0004] In view of the above problems, the present application provides a liquid metal composite gasket and a preparation method thereof. By combining composite spinning technology and composite material preparation process, the interface bonding between liquid metal and polyurethane matrix is optimized, and a continuous heat-conducting channel is built, thereby significantly improving the heat-conducting efficiency and resilience of the material.

[0005] Specifically, the liquid metal composite gasket is prepared by the following steps: (1) One or more of liquid metals gallium, indium, tin and bismuth are melted at 180-250℃, and heat preservation is performed to obtain a spinning solution A; (2) Polyester polyol and diisocyanate with a molar ratio of 2:1-4:1 are uniformly mixed and reacted at 70-90℃ for 0.5-1 hour to obtain a prepolymer B, and the NCO of the prepolymer B is 2.3-2.7; the polyester polyol is polybutylene adipate with a molecular weight of 1200-2100; and the diisocyanate is MDI or TDI; (3) Ethylene glycol, pentanediamine, diethylene triamine, ethanolamine and unsymmetrical dimethylhydrazine are mixed in a mass ratio of 60-80:28-35:2-4:1-3:1-2 to obtain a chain extender C; (4) The chain extender C is mixed with the prepolymer B, and the reaction is carried out in a screw extruder with a reaction temperature of 180-230℃ to obtain a polyurethane D; the mass ratio of the chain extender C to the prepolymer B is in the range of 1:40-1:50.

[0006] (5) Spinning liquid A and polyurethane D are respectively sprayed from the circular and annular holes of the concentric circular spinneret, the spinning speed is 100-200 m / min, wherein the radius of the circular hole is 0.2-0.3 mm, the outer radius of the annular hole is 0.25 mm-1 mm, the length-diameter ratio of the circular hole is 1:2-1:8, and the circular hole is 1-2 mm long from the annular hole; the spinneret draw ratio is 0.5-3 times, and after 10-30 mm, the temperature is 15-25 DEG C, the air layer speed is 3-15 m / min, and the air layer enters the 2-7 DEG C water bath to obtain the composite fiber E. The air layer can ensure the pre-coagulation and has a certain draft, so that the structure regularity is improved.

[0007] (6) 100 parts by weight of polyester polyol, 100 parts by weight of diisocyanate, 2-5 parts by weight of polyether polyol, and 2-4 parts by weight of water are uniformly mixed to obtain a pre-impregnation liquid F; the polyester polyol is polyethylene glycol adipate with a molecular weight of 1000-1500; the diisocyanate is TDI; the polyether polyol is polyethylene glycol ether with a molecular weight of 2000-3000; (7) The composite fiber E is immersed in the pre-impregnation liquid F, and the mass percentage of the pre-impregnation liquid is 10-30%, to obtain a pre-impregnated material G; the G is bundled, and according to different size requirements, it is molded by heating in different dies, the curing temperature is 70-120 DEG C, and the axial slice perpendicular to the pre-impregnated material G is obtained. The thickness of the slice is 0.2-2 mm.

[0008] Further, the liquid metal in step 1 can be composed of gallium, indium and tin with a mass ratio of (50-70):(15-25):(5-35).

[0009] Further, the spinning liquid A is composed of gallium and indium with a mass ratio of (55-75):(25-45).

[0010] Further, the spinning liquid A is composed of bismuth, indium and tin with a mass ratio of (40-60):(20-30):(10-40).

[0011] The present application has the advantages that: the liquid metal is used as a heat-conducting phase, which is uniformly distributed in the polyurethane matrix by combining the composite spinning technology, effectively constructing the heat-conducting path, and significantly improving the heat-conducting performance. At the same time, by accurately controlling the interface combination of the liquid metal and the polyurethane, the interface thermal resistance is reduced, and the overall heat conduction efficiency is improved.

[0012] In addition, the cross-linked structure of the polyurethane matrix and the fluidity of the liquid metal are combined to give the gasket excellent rebound performance, which is suitable for sealing and buffering requirements under complex working conditions.

[0013] The composite gasket obtained has a thermal resistance of ≤0.06℃cm2 / W @40Psi, a density of <1.2g / cc, a resilience of ≥60%, a tensile strength of >0.05MPa, a compression of >40% @40Psi, a compression stress of ≤65Psi @50% / 10min, and a creep of ≤1mm. DETAILED DESCRIPTION

[0014] The following examples are provided to further illustrate the present application and are not intended to limit the scope of the present application. Unless otherwise indicated, parts and percentages are by weight.

[0015] The raw materials used in the present application are conventional commercially available products unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified.

[0016] The present application is further illustrated in the following examples.

[0017] It should be apparent that the described embodiments are only some but not all of embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative effort shall fall within the scope of the present application.

[0018] The terms used in the present application are merely for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0019] Example 1 (1) 50wt% gallium, 15wt% indium, 35wt% tin were melted at 180℃, and heat preservation was performed to obtain a spinning solution A; (2) Polybutylene adipate and MDI in a molar ratio of 2:1 were mixed uniformly and reacted at 70℃ for 1 hour to obtain a prepolymer B; (3) Ethylene glycol, pentanediamine, diethylene triamine, ethanolamine, and unsymmetrical dimethylhydrazine were mixed in a mass ratio of 60:28:2:1:1 to obtain a mixed chain extender C; (4) The chain extender C was mixed with the prepolymer B, and a reaction was performed in a screw extruder with a reaction temperature of 180℃ to obtain a polyurethane D; the mass ratio of the chain extender C to the prepolymer B was 1:40.

[0020] (5) Liquid metal A and polyurethane D are respectively sprayed from the circular and annular holes of the concentric circular spinneret, with a spinning speed of 100 m / min, wherein the radius of the circular hole is 0.2 mm, the outer radius of the annular hole is 0.25 mm, the length-diameter ratio of the circular hole is 1:2, and the circular hole is 1 mm longer than the annular hole; the spinneret draw ratio is 0.5 times, and after 10 mm, the air layer with a temperature of 15℃ and a wind speed of 3 m / min enters a 7℃ water bath to obtain composite fiber E.

[0021] (6) 100 parts by weight of polyethylene glycol adipate with a molecular weight of 1000-1500, 100 parts by weight of TDI, 2 parts by weight of polyethylene glycol ether with a molecular weight of 2000-3000, and 2 parts by weight of water are uniformly mixed to obtain a pre-impregnation solution F; (7) The composite fiber E is immersed in the pre-impregnation solution F, and the mass percentage of the pre-impregnation solution is 10%, to obtain a pre-impregnated material G; the G is bundled and molded by heating through a die, with a curing temperature of 70℃, and then sliced into 0.2 mm to obtain a composite gasket. The gasket obtained has a thermal resistance of 0.04℃cm² / W @40Psi, a density of 1.0 g / cc, a resilience of 70%, a tensile strength of 0.05 MPa, a compression rate of 60% @40Psi, a compression stress of 60 Psi @50% / 10 min, and a creep of 1 mm.

[0022] Example 2 (1) 70wt% gallium, 25wt% indium, and 5wt% tin are melted at 180℃ to obtain a spinning solution A; (2) Polybutylene glycol adipate and TDI with a molar ratio of 4:1 are uniformly mixed and reacted at 90℃ for 0.5 hours to obtain a prepolymer B; (3) Ethylene glycol, pentanediamine, diethylene triamine, ethanolamine, and unsymmetrical dimethylhydrazine are mixed in a mass ratio of 80:35:4:3:2 to obtain a mixed chain extender C; (4) The chain extender C and the prepolymer B are mixed and reacted in a screw extruder, with a reaction temperature of 180℃, to obtain polyurethane D; the mass ratio of the chain extender C to the prepolymer B is 1:50.

[0023] (5) Liquid metal A and polyurethane D are respectively sprayed from the circular and annular holes of the concentric circular spinneret, with a spinning speed of 200 m / min, wherein the radius of the circular hole is 0.3 mm, the outer radius of the annular hole is 1 mm, the length-diameter ratio of the circular hole is 1:8, and the circular hole is 2 mm longer than the annular hole; the spinneret draw ratio is 3 times, and after 30 mm, the air layer with a temperature of 25℃ and a wind speed of 15 m / min enters a 2℃ water bath to obtain composite fiber E.

[0024] (6) 100 parts by weight of polyethylene adipate with a molecular weight of 1000-1500, 100 parts by weight of TDI, 5 parts by weight of polyethylene glycol ether with a molecular weight of 2000-3000, and 4 parts by weight of water are mixed uniformly to obtain a pre-impregnation solution F; (7) The composite fiber E is dip-coated with the pre-impregnation solution F, and the mass percentage of the pre-impregnation solution is 30%, to obtain a pre-impregnated material G; the G is bundled and molded by heating at a die to obtain a 2mm-thick composite gasket. The thermal resistance of the obtained gasket is 0.06°Ccm2 / W @40Psi, the density is 1.2g / cc, the resilience is 70%, the tensile strength is 0.1MPa, the compression rate is 40% @40Psi, the compression stress is 65Psi @50% / 10min, and the creep is 0.5mm.

[0025] Example 3 The difference from Example 1 is that the spinning solution A is composed of 55wt% gallium and 45wt% indium. The thermal resistance of the obtained gasket is 0.05°Ccm2 / W @40Psi, the density is 0.9g / cc, the resilience is 60%, the tensile strength is 0.11MPa, the compression rate is 45% @40Psi, the compression stress is 60Psi @50% / 10min, and the creep is 0.7mm.

[0026] Example 4 The difference from Example 1 is that the spinning solution A is composed of 75wt% gallium and 25wt% indium. The thermal resistance of the obtained gasket is 0.06°Ccm2 / W @40Psi, the density is 1.2g / cm3, the resilience is 68%, the tensile strength is 0.09MPa, the compression rate is 41% @40Psi, the compression stress is 62Psi @50% / 10min, and the creep is 0.45mm.

[0027] Example 5 The difference from Example 2 is that the spinning solution A is composed of 40wt% bismuth, 20wt% indium, and 40wt% tin. The thermal resistance of the obtained composite gasket is 0.06°Ccm2 / W @40Psi, the density is 1.1g / cm3, the resilience is 61%, the tensile strength is 0.08MPa, the compression rate is 40% @40Psi, the compression stress is 62Psi @50% / 10min, and the creep is 1.0mm.

[0028] Example 6 The difference from Example 1 is that the dope A consists of 60wt% bismuth, 30wt% indium, 10wt% tin. The resulting gasket has a thermal resistance of 0.05°C-cm2 / W @ 40 Psi, a density of 1.0 g / cm3, a resiliency of 60%, a tensile strength of 0.09 MPa, a compressibility of 44% @ 40 Psi, a compressive stress of 65 Psi @ 50% / 10 min, and a creep of 0.8 mm.

[0029] Example 7 The difference from Example 2 is that the dope A is gallium. The resulting composite gasket has the lowest thermal resistance of 0.03°C-cm2 / W @ 40 Psi, the lowest density (0.7 g / cm3), a compressibility of 90% @ 40 Psi, but a resiliency of 60%, a tensile strength of 0.07 MPa, a compressive stress of 55 Psi @ 50% / 10 min, and a creep of 1 mm.

[0030] The above examples illustrate the structure, features and effects of the present application. The above description is only the preferred embodiments of the present application. Any changes made in accordance with the concept of the present application, or any equivalent embodiments with equivalent changes, shall be within the scope of the present application.

Claims

1. A method of making a liquid metal composite gasket, comprising: Having the following steps: ​ (1) melt one or more of liquid metal gallium, indium, tin, bismuth at 180~250℃ to obtain a spinning solution A; (2) mix polyester polyol and diisocyanate with a molar ratio of 2:1~4:1 uniformly, and react at 70~90℃ for 0.5~1 hour to obtain a prepolymer B; (3) mix ethylene glycol, pentanediamine, diethylene triamine, ethanolamine, and methylhydrazine with a mass ratio of 60~80:28~35:2~4:1~3:1~2 to obtain a chain extender C; (4) mix the chain extender C with the prepolymer B and react in a screw extruder, the reaction temperature is 180~230℃, to obtain a polyurethane D; (5) spin the spinning solution A and the polyurethane D from the circular hole and the circular ring hole of the concentric spinning hole respectively, wherein the circular spinning hole is 1~2mm longer than the circular ring spinning hole; the spinning head draw ratio is 0.5~3 times, and after 10~30mm, the temperature is 15~25℃, the air layer speed is 3~15m / min, and it enters the water bath of 2~7℃ to obtain a composite fiber E; (6) mix 100 parts by weight of polyester polyol, 100 parts by weight of diisocyanate, 2~5 parts by weight of polyether polyol, and 2~4 parts by weight of water uniformly to obtain a pre-impregnation solution F; (7) dip coat the composite fiber E with the pre-impregnation solution F, the mass percentage of the pre-impregnation solution is 10~30%, to obtain a pre-impregnated material G; bundle the G and heat and cure to form, the curing temperature is 70~120℃, and the axial slice perpendicular to the pre-impregnated material G obtains a composite gasket.

2. The method of claim 1, wherein, The polyester polyol in step 2 is polybutylene adipate with a molecular weight of 1200~2100; and the diisocyanate is MDI or TDI.

3. The method of claim 1, wherein, The spinning solution A is composed of gallium, indium, and tin with a mass ratio of (50-70):(15-25):(5-35).

4. The method of claim 1, wherein, The spinning solution A is composed of gallium and indium with a mass ratio of (55-75):(25-45).

5. The method of claim 1, wherein, The spinning solution A is composed of bismuth, indium, and tin with a mass ratio of (40-60):(20-30):(10-40).

6. The method of claim 1, wherein, The speed of the ejection in step 5 is 100~200m / min.

7. The method of claim 1, wherein, The radius of the circular hole in step 5 is 0.2~0.3mm, the outer radius of the circular ring hole is 0.25mm~1mm, and the length-diameter ratio of the circular hole is 1:2~1:

8.

8. The method of claim 1, wherein, The polyester polyol in step 6 is polyethylene adipate with a molecular weight of 1000~1500; the diisocyanate is TDI; and the polyether polyol is polyethylene glycol ether with a molecular weight of 2000~3000.

9. The method of claim 1, wherein, The thickness of the slice is 0.2-2mm.

10. A liquid metal composite gasket prepared by the method of claim 1.