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CN-122011780-A - High-heat-conductivity low-specific gravity composite gel and preparation method thereof

CN122011780ACN 122011780 ACN122011780 ACN 122011780ACN-122011780-A

Abstract

The application provides a high-heat-conductivity low-specific gravity composite gel and a preparation method thereof, belonging to the technical field of heat-conductivity functional materials, wherein the composite gel comprises 50-80% of heat-conductivity filler system and 20-50% of gel matrix, the heat-conductivity filler system comprises hexagonal boron nitride, hollow aluminum powder and powder surface modifier, the hexagonal boron nitride, the hollow aluminum powder and the powder surface modifier respectively account for 24-50%, 25-55% and 0.1-1.0% of the composite gel, the gel matrix comprises matrix resin, cross-linking agent and curing agent, and the matrix resin, the cross-linking agent and the curing agent respectively account for 18-45%, 1-4% and 0.5-1% of the composite gel. The application constructs a high heat conduction path-lightweight skeleton composite structure, and has the advantages of high heat conduction, low specific gravity and high insulativity.

Inventors

  • LIU BIN
  • CHEN LIN
  • JIA XIAO
  • XU MIN

Assignees

  • 中国科学院工程热物理研究所

Dates

Publication Date
20260512
Application Date
20260312

Claims (10)

  1. 1. The high-heat-conductivity low-specific gravity composite gel is characterized by comprising 50-80% of a heat-conducting filler system and 20-50% of a gel matrix, wherein the heat-conducting filler system comprises 24-50%, 25-55% and 0.1-1.0% of hexagonal boron nitride, hollow aluminum powder and a powder surface modifier, the gel matrix comprises a matrix resin, a cross-linking agent and a curing agent, and the matrix resin, the cross-linking agent and the curing agent respectively account for 18-45%, 1-4% and 0.5-1% of the composite gel.
  2. 2. The high-thermal-conductivity low-specific gravity composite gel and the preparation method thereof according to claim 1, wherein the hexagonal boron nitride is micron-sized platelets with the platelet thickness less than or equal to 1 μm, the particle size is 15-50 μm, and the in-plane thermal conductivity is more than or equal to 300W/(m.K).
  3. 3. The high-heat-conductivity low-specific gravity composite gel and the preparation method thereof according to claim 1, wherein the hollow aluminum powder has a particle size of 10-80 μm, a hollow rate of 50-80%, an aluminum shell thickness of 1-5 μm and a specific gravity of 0.4-0.7 g/cm 3 .
  4. 4. The high-thermal-conductivity low-specific gravity composite gel and the preparation method thereof according to claim 1, wherein the powder surface modifier is a vinyl silane coupling agent oligomer, and the polymerization degree is 3-10.
  5. 5. The high-thermal-conductivity low-specific gravity composite gel and the preparation method thereof according to claim 1, wherein the matrix resin is vinyl silicone resin, and the viscosity of the vinyl silicone resin is 100-1000 mPa.s.
  6. 6. The high-thermal-conductivity low-specific gravity composite gel according to claim 1, wherein the cross-linking agent is hydrogen-containing silicone oil, and the hydrogen content of the hydrogen-containing silicone oil is 0.05% -0.36%.
  7. 7. The high-thermal-conductivity low-specific gravity composite gel according to claim 1, wherein the curing agent is a platinum catalyst, and the content is 3000ppm.
  8. 8. A method of preparing the high thermal conductivity low specific gravity composite gel according to any of claims 1 to 7, wherein the method comprises: Adding hexagonal boron nitride and hollow aluminum powder into absolute ethyl alcohol, performing ultrasonic dispersion, adding a powder surface modifier according to 0.5-2% of the weight of the hollow aluminum powder to form suspension, stirring and reacting at 60-80 ℃, adding a cross-linking agent according to 1-5% of the weight of the added powder surface modifier, stirring and reacting at 10-20 ℃, atomizing the suspension into micron-sized spherical liquid drops by adopting a centrifugal spray dryer, and drying to obtain the core-shell type composite filler of the hollow aluminum powder-hexagonal boron nitride; The preparation method of the gel comprises the steps of mixing matrix resin, a cross-linking agent and a curing agent in proportion, stirring at room temperature to form a uniform resin matrix, gradually adding the obtained core-shell type composite filler into the resin matrix, mechanically stirring at 50-70 ℃, simultaneously dispersing by adopting ultrasonic, continuing stirring, and removing bubbles by vacuum defoaming to obtain a composite gel finished product.
  9. 9. The method according to claim 8, wherein in the surface modification step of hexagonal boron nitride and hollow aluminum powder, the ultrasonic dispersion time is 10 to 20 minutes, the ultrasonic dispersion power is 150 to 250w, the stirring reaction is performed for 30 to 60 minutes at 60 to 80 ℃, and the stirring reaction is performed for 5 to 15 minutes at 10 to 20 ℃.
  10. 10. The method according to claim 8, wherein in the step of preparing the gel, the time of mechanical stirring is 30 to 60 minutes, the rotational speed of mechanical stirring is 500 to 1000 r/min, the power of ultrasonic dispersion is 200 to 400w, and the time of ultrasonic dispersion is 20 to 40 minutes.

Description

High-heat-conductivity low-specific gravity composite gel and preparation method thereof Technical Field The application relates to the technical field of heat conduction functional materials, in particular to a high-heat conduction low-specific gravity composite gel and a preparation method thereof. Background With the development of new energy automobiles to high voltage and high power density, the heat dissipation requirement of a battery thermal management system is further improved, and the requirement on heat conduction materials is changed from single heat conduction to 'light weight and high heat conduction' multifunctional integration. The existing heat-conducting gel material for the traditional new energy automobile has the technical defects that aluminum oxide, zinc oxide, aluminum hydroxide and the like are used as heat-conducting fillers, the heat conductivity coefficient is generally lower than 6W/(m.K), the filler content (generally more than or equal to 70%) is required to be increased for improving the heat-conducting property, the specific gravity of the material is increased (more than or equal to 2.5 g/cm 3), and the light-weight requirement cannot be met. Boron nitride (h-BN) has a graphite-like layered structure and excellent heat conductivity coefficient (in-plane: not less than 300W/(m.K)), but the lamellar layer is easy to agglomerate, the oil absorption value is high, and high-quality fraction filling is difficult to realize, so that the heat conductivity coefficient of gel by single hexagonal boron nitride (h-BN) is limited (usually not more than 5W/(m.K)), and meanwhile, the h-BN density (2.27 g/cm 3) is still higher, so that the lightweight effect is poor. The specific gravity of the hollow aluminum powder is low (0.3-0.8 g/cm 3), the overall density of the material can be obviously reduced, but the aluminum powder has conductivity, and the breakdown voltage is lower than 3 kv/mm when the aluminum powder is used alone, so that the requirement of a new energy battery pack on insulativity cannot be met. The existing composite heat-conducting gel has the contradiction that the synergistic effect and interface combination of the filler are not optimized, the high heat conduction, the low specific gravity and the insulativity can not be achieved, and the mechanical strength and the aging resistance of the gel are insufficient. Therefore, the development of the composite gel material with high heat conductivity, low specific gravity and good insulativity through the synergy of the hexagonal boron nitride and the hollow aluminum powder becomes a key for solving the heat conduction and light weight requirements of the heat management material of the new energy automobile. Disclosure of Invention In view of the above, the embodiment of the application provides a high-heat-conductivity low-specific gravity composite gel and a preparation method thereof, which at least partially solve the problems of 'high heat conductivity, low specific gravity and insulativity can not be combined, and insufficient mechanical strength and aging resistance' existing in the prior art. In a first aspect, the embodiment of the application provides a gel matrix comprising 50% -80% by weight of a composite gel of a heat conducting filler system and 20% -50% by weight of a gel matrix, wherein the heat conducting filler system comprises 24% -50% by weight of hexagonal boron nitride, 25% -55% by weight of hollow aluminum powder and 0.1% -1.0% by weight of a powder surface modifier of the composite gel, the gel matrix comprises 18% -45% by weight of a matrix resin, 1% -4% by weight of a cross-linking agent and 0.5% -1% by weight of a curing agent of the composite gel. According to a specific implementation mode of the embodiment of the application, the hexagonal boron nitride is micron-sized platelets with the platelet thickness less than or equal to 1 mu m, the particle size is 15-50 mu m, and the in-plane heat conductivity coefficient is more than or equal to 300W/(m.K). According to a specific implementation mode of the embodiment of the application, the particle size of the hollow aluminum powder is 10-80 mu m, the hollow rate is 50-80%, the thickness of the aluminum shell is 1-5 mu m, and the specific gravity is 0.4-0.7 g/cm 3. According to a specific implementation mode of the embodiment of the application, the powder surface modifier is a vinyl silane coupling agent oligomer, and the polymerization degree is 3-10. According to a specific implementation mode of the embodiment of the application, the matrix resin is vinyl organic silicon resin, and the viscosity of the vinyl organic silicon resin is 100-1000 mPa.s. According to a specific implementation mode of the embodiment of the application, the cross-linking agent is hydrogen-containing silicone oil, and the hydrogen content of the hydrogen-containing silicone oil is 0.05% -0.36%. According to a specific implementation mode of the embodiment of the appli