A phase change type heat conductive interface material and a preparation method thereof

Abstract

The application discloses a phase change type heat-conducting interface material and a preparation method thereof, and relates to the technical field of heat-dissipating materials. The phase change type heat-conducting interface material comprises a porous graphene film and a composite phase change material filled in the pore channel of the porous graphene film. The composite phase change material comprises the following components in parts by mass: 1-5 parts of paraffin, 1-5 parts of liquid polyolefin resin and 85-105 parts of heat-conducting fillers. The viscosity of the liquid polyolefin resin at 25 DEG C is 10000-50000 mPa.s. The particle size of the heat-conducting fillers is 1-5 microns. The phase change type heat-conducting interface material provided by the application has the advantages of ultralow thermal resistance, excellent in-plane heat diffusion capacity and anti-pumping performance under long-term thermal cycle, and is suitable for reliable heat dissipation of high-power-density electronic devices.

Description

Technical Field

[0001] This invention relates to the field of electronic heat dissipation technology, and in particular to a phase change thermally conductive interface material and its preparation method. Background Technology

[0002] Phase change interface (PCI) materials, due to their ability to soften and flow near the phase change temperature and fill interfacial micropores, exhibit low thermal resistance and are widely used in electronic heat dissipation. However, traditional PCI materials (such as paraffin-based composites) are prone to "pump-out" during repeated thermal cycling. This occurs when molten material is squeezed out of the interface between the chip and the heat sink due to thermal expansion and contraction and mechanical vibration, leading to contact failure, a sharp increase in thermal resistance, and severely impacting the long-term reliability of the device. Existing anti-pump-out strategies include: adding high-viscosity polymers or elastomers to improve material cohesion, but often sacrificing thermal conductivity; using microencapsulation technology to encapsulate PCI materials, but the shell introduces additional thermal resistance; and using foamed metals or porous carbon materials as carriers, but these have insufficient in-plane thermal diffusion capacity, making it difficult to achieve rapid lateral heat conduction.

[0003] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a phase change thermally conductive interface material and its preparation method, aiming to provide a phase change thermally conductive interface composite material with high thermal conductivity, low thermal resistance and strong anti-pumping performance.

[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a phase change thermally conductive interface material, comprising a porous graphene film and a composite phase change material filling the pores of the porous graphene film. The composite phase change material comprises the following components by mass: 1-5 parts paraffin wax, 1-5 parts liquid polyolefin resin, and 85-105 parts thermally conductive filler; The viscosity of the liquid polyolefin resin at 25°C is 10,000–50,000 mPa·s. The particle size of the thermally conductive filler is 1~5 μm.

[0006] Optionally, the phase transition temperature of the paraffin is 45–60°C; and / or, The liquid polyolefin resin has a viscosity of 20,000~50,000 mPa·s at 25°C; and / or, The thermally conductive filler comprises 85-105 parts, including 80-90 parts of a first filler and 5-15 parts of a second filler; the particle size of the first filler is 3-5 μm, and the particle size of the second filler is 1-5 μm; the first filler includes at least one of alumina, aluminum nitride, diamond, boron nitride, and aluminum powder; and the second filler includes zinc oxide.

[0007] Optionally, the second filler further includes at least one of an antioxidant and a coupling agent; The antioxidants include at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants; The coupling agent includes at least one of silane coupling agents and titanate coupling agents.

[0008] Optionally, the liquid polyolefin resin includes at least one selected from polybutene, hydrogenated polybutadiene, polyisobutylene, polyα-olefin, and hydrogenated polyisoprene; and / or, The thickness of the porous graphene film is 20~500 μm; and / or, The thermal diffusivity of the porous graphene film is greater than or equal to 500 mm. 2 / s; and / or, The porous graphene film has a density of 0.07~0.18 g / cm³. 3 .

[0009] Optionally, the pores in the porous graphene film are through-holes in the thickness direction, and the through-holes are distributed in an array; in the planar direction of the porous graphene film, the total area of ​​the through-holes accounts for 10% to 95% of the area of ​​the porous graphene film.

[0010] Optionally, the diameter of the through hole is 20~100 μm.

[0011] A second aspect of the present invention provides a method for preparing the phase change thermally conductive interface material as described above, comprising the following steps: Provide porous graphene membranes; The composite phase change material is prepared into a flexible sheet, which is then placed on the surface of the porous graphene film and hot-pressed to melt and fill the pores of the porous graphene film, thereby obtaining the phase change thermally conductive interface material.

[0012] Optionally, the process parameters used in the hot pressing are: The temperature is 60~100 ℃, the pressure is 0.1~1 MPa, and the time is 5~10 min.

[0013] Optionally, the dimensions of the flexible sheet are the same as those of the porous graphene film; Composite phase change materials are prepared into flexible sheets by hot pressing.

[0014] Optionally, the method for preparing the porous graphene membrane includes the following steps: Provide graphene films; Laser drilling is performed on the graphene film to form an array of through holes in the plane of the graphene film, thus obtaining the porous graphene film.

[0015] Beneficial effects: On the one hand, this invention uses a highly thermally conductive porous graphene film as a three-dimensional confinement framework. This porous graphene film not only provides ultra-high in-plane thermal diffusion capacity but also effectively anchors the composite phase change material through its pores, forming a mechanically interlocked structure. This firmly binds the composite phase change material within the pores, making it difficult to migrate or be extruded even under long-term thermal cycling, significantly improving reliability. In other words, the porous graphene film acts as a physical confinement carrier for the composite phase change material, providing ultra-high in-plane thermal diffusion capacity while fundamentally suppressing pumping out. On the other hand, this invention introduces a liquid polyolefin resin with a viscosity of 10,000~50,000 mPa·s into the composite phase change material, significantly improving its cohesion and viscoelasticity; simultaneously, it combines this with thermally conductive fillers with a particle size of 1~5 μm to construct a dense thermally conductive network. The synergistic effect of these three elements further suppresses flow and enhances anti-pumping performance without significantly sacrificing wettability.

[0016] Therefore, the phase change thermal interface material provided by this invention has ultra-low thermal resistance, excellent in-plane thermal diffusion capability and anti-pumping performance under long-term thermal cycling, making it suitable for reliable heat dissipation of high power density electronic devices. Attached Figure Description

[0017] Figure 1 This is a top view schematic diagram of the porous graphene membrane in an embodiment of the present invention.

[0018] Figure 2 This is a flowchart illustrating the preparation process of the phase change thermally conductive interface material in an embodiment of the present invention. Detailed Implementation

[0019] This invention provides a phase change thermally conductive interface material and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0021] If the embodiments of the present invention involve descriptions such as "first" or "second", such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0022] This invention provides a phase change thermally conductive interface material, comprising a porous graphene film and a composite phase change material filling the pores of the porous graphene film. The composite phase change material comprises the following components by mass: 1-5 parts paraffin wax, 1-5 parts liquid polyolefin resin, and 85-105 parts thermally conductive filler; The viscosity of the liquid polyolefin resin at 25°C is 10,000 to 50,000 mPa·s (for example, it can be 10,000 mPa·s, 20,000 mPa·s, 30,000 mPa·s, 40,000 mPa·s, or 50,000 mPa·s, etc.). The particle size of the thermally conductive filler is 1~5 μm.

[0023] On the one hand, this invention uses a highly thermally conductive porous graphene film as a three-dimensional confinement framework. This porous graphene film not only provides ultra-high in-plane thermal diffusion capacity but also effectively anchors the composite phase change material through its pores, forming a mechanically interlocked structure. This firmly binds the composite phase change material within the pores, making it difficult to migrate or be extruded even under long-term thermal cycling, significantly improving reliability. In other words, the porous graphene film acts as a physical confinement carrier for the composite phase change material, providing ultra-high in-plane thermal diffusion capacity while fundamentally suppressing pumping out. On the other hand, this invention introduces a liquid polyolefin resin with a viscosity greater than or equal to 10,000~50,000 mPa·s into the composite phase change material, significantly improving its cohesion and viscoelasticity. Simultaneously, it combines this with thermally conductive fillers with a particle size of 1~5 μm to construct a dense thermally conductive network. The synergistic effect of these three elements further suppresses flow and enhances anti-pumping performance without significantly sacrificing wettability.

[0024] Therefore, the phase change thermal interface material provided by this invention has ultra-low thermal resistance, excellent in-plane thermal diffusion capability and anti-pumping performance under long-term thermal cycling, making it suitable for reliable heat dissipation of high power density electronic devices.

[0025] In some embodiments, the phase transition temperature of the paraffin is 45–60°C (e.g., 45°C, 50°C, 55°C, or 60°C, etc.); the viscosity of the liquid polyolefin resin at 25°C is 20,000–50,000 mPa·s. The thermally conductive filler comprises 85-105 parts, including 80-90 parts of a first filler and 5-15 parts of a second filler; the particle size of the first filler is 3-5 μm, and the particle size of the second filler is 1-5 μm; the first filler includes at least one selected from alumina, aluminum nitride, diamond, boron nitride, and aluminum powder; the second filler includes zinc oxide. Preferably, the thermally conductive filler comprises 80-90 parts of aluminum powder (particle size 3-5 μm) and 5-15 parts of zinc oxide (particle size 1-5 μm).

[0026] Specifically, liquid polyolefin resins with a viscosity of 20,000–50,000 mPa·s can form a highly cohesive viscoelastic network within the gaps of a multi-scale filler skeleton composed of a first filler (such as aluminum powder) and a second filler (such as zinc oxide). When paraffin wax melts, this network effectively binds liquid paraffin molecules through physical entanglement and interfacial adsorption, significantly inhibiting their migration caused by gravity or capillary action. Simultaneously, the synergistic stacking of micron-sized aluminum powder and zinc oxide constructs a low-porosity, highly continuous thermally conductive pathway. The combined effect of these three factors achieves a balance between high thermal conductivity and excellent anti-pumping performance while maintaining good processing wettability.

[0027] In some embodiments, the liquid polyolefin resin includes, but is not limited to, at least one of polybutene, hydrogenated polybutadiene, polyisobutylene, polyalphaolefin (PAO), and hydrogenated polyisoprene (HPIP). These liquid polyolefin resins can form a highly cohesive viscoelastic network within the gaps of a multi-scale filler skeleton composed of a first filler (e.g., aluminum powder) and a second filler (e.g., zinc oxide). When paraffin wax melts, this network effectively binds liquid paraffin molecules through physical entanglement and interfacial adsorption, significantly inhibiting their migration due to gravity or capillary action. Simultaneously, the synergistic stacking of micron-sized aluminum powder and zinc oxide constructs a low-porosity, highly continuous thermally conductive pathway. The combined effect of these three factors achieves a balance between high thermal conductivity and excellent anti-pumping performance while maintaining good processing wettability.

[0028] In some embodiments, the second filler further includes at least one of an antioxidant and a coupling agent.

[0029] In some embodiments, the antioxidant includes, but is not limited to, at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants. These antioxidants are used to inhibit the oxidative degradation of paraffin and liquid polyolefin resins during long-term thermal cycling, maintaining the stability of material properties.

[0030] In some specific embodiments, the hindered phenolic antioxidant includes, but is not limited to, at least one of antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and antioxidant 1076 (octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). These antioxidants can effectively inhibit the oxidative degradation of paraffin and liquid polyolefin resins during long-term thermal cycling, maintaining the stability of material properties.

[0031] In some specific embodiments, the phosphite antioxidant includes, but is not limited to, antioxidant 168 (tris[2,4-di-tert-butylphenyl]phosphite). This antioxidant can effectively inhibit the oxidative degradation of paraffin and liquid polyolefin resins during long-term thermal cycling, maintaining the stability of material properties.

[0032] In some specific embodiments, the thioester antioxidants include, but are not limited to, at least one of the following antioxidants: DLTP (dilauryl thiodipropionate), DLTP (disodecayl thiodipropionate), DTDTP (disetetane 3,3'-dithiodipropionate), and β-mercaptopropionate octadecyl ester. These antioxidants can effectively inhibit the oxidative degradation of paraffin and liquid polyolefin resins during long-term thermal cycling, maintaining the stability of material properties.

[0033] In one embodiment, the coupling agent comprises, but is not limited to, at least one of a silane coupling agent and a titanate coupling agent. Specifically, the silane coupling agent comprises, but is not limited to, at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane (i.e., KH-550 silane coupling agent), N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, octyltriethoxysilane, and isooctyltriethoxysilane.

[0034] These coupling agents effectively improve the interfacial compatibility between thermally conductive fillers (aluminum powder, zinc oxide) and organic matrices (paraffin wax, polyolefin resin), promote the formation of thermally conductive networks, reduce interfacial thermal resistance, and further enhance the cohesion of the composite material, thereby synergistically strengthening its anti-pumping performance. Specifically, these coupling agents can form molecular bridges on the surfaces of aluminum powder and zinc oxide, improving interfacial adhesion with the continuous phases of liquid polyolefin resin and paraffin wax. Furthermore, the addition of coupling agents reduces the viscosity of the system, results in more uniform dispersion of aluminum powder, and a denser thermally conductive network.

[0035] In some embodiments, the thickness of the porous graphene film is 20~500 μm, for example, it can be 20 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, or 500 μm. At this thickness, the porous graphene film has good vertical thermal conductivity. Combined with the filling of aluminum powder and zinc oxide, a multi-level thermally conductive network can be constructed, and the interfacial thermal resistance can be controlled at a low level.

[0036] In some embodiments, the thermal diffusivity of the porous graphene film is greater than or equal to 500 mm. 2 / s.

[0037] In some specific embodiments, the thermal diffusivity of the porous graphene film is greater than or equal to 800 mm. 2 / s.

[0038] In some embodiments, the density of the porous graphene film is 0.07~0.18 g / cm³. 3 For example, it can be 0.07 g / cm³. 3 0.08 g / cm 3 0.10 g / cm 3 0.11 g / cm 3 0.12 g / cm 3 0.13 g / cm 3 0.14 g / cm 3 0.15 g / cm 3 0.16 g / cm 3 0.17 g / cm 3 Or 0.18 g / cm 3 The density of the porous graphene film is preferably 0.10 g / cm³. 3 On the one hand, the sufficient graphene sheet connections in the porous graphene film ensure efficient phonon transport, significantly improving the in-plane thermal diffusion capability of the composite material. On the other hand, the micron-scale through-pore structure provides strong capillary adsorption force, effectively confining molten paraffin and suppressing pumping out. Simultaneously, the film at this density possesses suitable mechanical flexibility, facilitating composite with highly filled aluminum powder and avoiding interfacial debonding or structural damage, thus achieving synergistic optimization of enhanced thermal conductivity and shape stability.

[0039] Specifically, the present invention provides a thermal diffusivity ≥ 500 mm. 2 / s (preferably ≥800 mm) 2 (g / s), density is 0.07~0.18 g / cm³ 3A self-supporting porous graphene membrane is used as a physical confinement carrier for composite phase change materials. It not only provides ultra-high in-plane thermal diffusion capability, but also effectively anchors the composite phase change material through its pore structure, fundamentally suppressing pumping out.

[0040] In some embodiments, the channels in the porous graphene film are through-holes in the thickness direction (i.e., through-holes penetrating the upper and lower surfaces of the porous graphene film), and the through-holes are distributed in an array; in the planar direction of the porous graphene film (i.e., the direction perpendicular to the thickness direction), the total area of ​​the through-holes accounts for 10% to 95% of the area of ​​the porous graphene film (for example, it can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 95%, etc.). As an example, such as... Figure 1 As shown, in the planar direction of the porous graphene film, the area of ​​the porous graphene (taking a rectangle as an example) is the value of a×b (where a is the side length of one side and b is the side length of the other side). The total area of ​​the through holes is the total area of ​​the 12 holes.

[0041] In this embodiment, the area ratio of the through hole can be selected according to actual needs. By adjusting the area ratio of the through hole, a flexible balance can be achieved between thermal resistance and tensile strength (e.g., the thermal resistance is lowest when the area ratio of the through hole is 90%, and the tensile strength is highest when the area ratio of the through hole is 10%). This enables the tunable design of thermal resistance and mechanical properties to meet the differentiated requirements of thermal conductivity and mechanical stability in different application scenarios, and has high engineering practicality and design freedom.

[0042] In some embodiments, the pore size (i.e., pore diameter) of the through-hole is 20~100 μm, for example, it can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm. Such a pore size is more conducive to ensuring that the phase change thermally conductive interface material has sufficient thermal conductivity and anti-pumping performance. Using a porous graphene film with an optimized pore size range (i.e., pore size of 20~100 μm), it can be well matched with the rheological properties of molten paraffin and the particle size (1~5 μm) of the thermally conductive filler: on the one hand, it provides sufficient capillary driving force to ensure that the phase change material is efficiently and uniformly impregnated into the pores, achieving high loading rate and excellent anti-pumping performance; on the other hand, it allows aluminum powder particles to be partially embedded or closely attached to the pore area during the molding process, constructing a three-dimensional thermally conductive network with low interfacial thermal resistance, significantly improving the thermal diffusion capability of the composite material in the thickness direction. At the same time, this pore size range ensures functionality while avoiding excessive weakening of the porous graphene membrane framework, thus maintaining its structural integrity.

[0043] Graphene films possess ultra-high in-plane thermal conductivity. By constructing a three-dimensional porous structure on the graphene film and using it as a confined framework for the phase change material, high thermal conductivity, low thermal resistance, and strong anti-pumping properties can be achieved. However, effectively embedding the phase change material into the graphene channels while maintaining structural integrity remains a technical challenge. Based on this, embodiments of the present invention also provide a method for preparing the phase change thermally conductive interface material as described above, wherein, as... Figure 2 As shown, it includes the following steps: S1. Provides porous graphene membrane; S2. The composite phase change material is prepared into a flexible sheet, the flexible sheet is placed on the surface of the porous graphene film, and then hot-pressed to melt the flexible sheet and fill the pores of the porous graphene film to obtain the phase change thermally conductive interface material.

[0044] In this invention, the composite phase change material is not simply coated onto the surface of a porous graphene film, nor is the porous graphene film immersed in molten composite phase change material. Instead, during the hot pressing process, paraffin wax melts, liquid polyethylene resin reduces fluidity, and the molten composite phase change material, driven by capillary force and pressure, fully penetrates and fills the pores of the porous graphene (i.e., the flexible sheet melts, fully wetting and filling the pores of the porous graphene), forming a mechanically interlocking structure. This ensures that the composite phase change material is firmly bound in the pores, forming an integrated "skeleton-filler" composite structure, improving anti-pumping performance and reliability.

[0045] A porous graphene film forms a physical confinement for the molten composite phase change material, which is then combined with a high-viscosity polyolefin resin to enhance cohesion and viscoelasticity. Simultaneously, thermally conductive fillers with particle sizes of 1–5 μm (specifically aluminum powder with a particle size of 3–5 μm and zinc oxide with a particle size of 1–5 μm) are used to construct a dense thermally conductive network. The synergistic effect of these three components further suppresses flow and enhances anti-pumping performance without significantly sacrificing wettability, thereby greatly improving the dimensional stability of the material during thermal cycling.

[0046] The preparation method provided by this invention can be implemented using roll-to-roll equipment, making it suitable for large-scale production.

[0047] In step S1, in some embodiments, the method for preparing the porous graphene membrane includes the following steps: Provide graphene films; Laser drilling is performed on the graphene film to form an array of through holes in the planar direction of the graphene film, thereby obtaining the porous graphene.

[0048] In step S2, in some embodiments, the composite phase change material is prepared into a flexible sheet by hot pressing. Specifically, liquid polyolefin resin, paraffin wax, a first filler, and a second filler are mixed and heated and stirred to obtain a paste-like mixture; the paste-like mixture is transferred to a heated roller press, the roller gap is adjusted, and the mixture is rolled at a preset temperature (e.g., 80 °C) to obtain a flexible sheet of a preset thickness.

[0049] In some embodiments, the process parameters used in the hot pressing are as follows: The temperature is 60~100℃ (e.g., 60℃, 70℃, 80℃, 90℃ or 100℃, etc.), the pressure is 0.1~1 MPa (e.g., 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa or 1 MPa), and the time is 5~10 min (e.g., 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc.).

[0050] In some embodiments, the dimensions of the flexible sheet are the same as those of the porous graphene film (taking a rectangular porous graphene film as an example, the two have the same dimensions, i.e., the length, width and thickness are the same).

[0051] By controlling the hot-pressing temperature, pressure, time, and thickness of the flexible sheet, it is possible to ensure that the composite phase change material is fully impregnated and filled into the porous graphene membrane pores in the molten state, while avoiding the flow or decomposition of the composite phase change material, thus achieving the optimal balance between structural integrity and interfacial wettability.

[0052] The present invention will be further described below through specific embodiments.

[0053] It should be noted that the following embodiments are for illustrative purposes only and do not constitute a limitation of the present invention. For example, in the present invention, the first filler includes at least one of alumina, aluminum nitride, diamond, boron nitride, and aluminum powder. The following embodiments are merely illustrative examples using aluminum powder and do not imply that the present invention can only use aluminum powder. In the present invention, the first filler can also be replaced with alumina, aluminum nitride, diamond, boron nitride, or a mixture thereof. Other raw materials in the present invention can also be understood in this way.

[0054] Unless otherwise specified, the raw materials and equipment involved in the following embodiments of the present invention are all conventional materials and equipment in the art, and can be obtained by purchasing commercially available products.

[0055] Example 1 This embodiment provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: A thickness of 250 μm and a density of 0.10 g / cm³ were used. 3 The thermal diffusivity is 800 mm. 2 A self-supporting graphene film with a wavelength of / s was placed on a laser processing platform. A nanosecond pulsed fiber laser with a wavelength of 1064 nm was used to perform array-type perforation on the surface of the graphene film, forming a uniform array of through holes with a pore size of 50 μm. The total area of ​​the through holes was controlled to account for 10% of the total area of ​​the graphene film. The resulting porous graphene film was denoted as G-10.

[0056] (2) Mixing and pressing of composite phase change material: 2 g of paraffin wax (phase change temperature of 50℃), 2 g of polyisobutylene (viscosity of 20000 mPa·s), 85 g of aluminum powder (particle size of 3 μm), 10 g of zinc oxide (particle size of 4 μm), 0.5 g of antioxidant 1010 and 0.5 g of KH-550 silane coupling agent were added to a double planetary mixer. Under nitrogen protection, the mixture was heated and stirred at 70 ℃ for 2 hours until a uniform, non-agglomerated paste mixture was obtained. The paste mixture was then transferred to a heated roller press (roller temperature of 80℃), the roller gap was adjusted, and the mixture was pressed into a flexible sheet with a thickness of 0.25 mm (i.e. 250 μm). After cooling, the sheet was cut into the same planar size as the graphene film and denoted as PCM-0.25.

[0057] (3) Hot-press composite molding: G-10 obtained in step (1) and PCM-0.25 obtained in step (2) are stacked together, so that PCM-0.25 covers the perforated surface of the porous graphene film. The stacked sample is placed in a flatbed hot press and held at 80 ℃ and 0.3 MPa for 8 minutes. During this process, the molten composite phase change material fully penetrates into the pores of the porous graphene film under the drive of capillary force and pressure. Then, it is naturally cooled to room temperature and demolded to obtain an integrated phase change thermally conductive interface material.

[0058] Example 2 This embodiment provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: The only difference from Example 1 is that the total area of ​​the through holes accounts for 50% of the total area of ​​the graphene film, and the resulting porous graphene film is called G-50.

[0059] (2) Mixing and pressing of composite phase change materials: Same as in Example 1.

[0060] (3) Hot pressing composite molding: The only difference from Example 1 is that G-10 is replaced with G-50.

[0061] Example 3 This embodiment provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: The only difference from Example 1 is that the total area of ​​the through holes accounts for 70% of the total area of ​​the graphene film, and the resulting porous graphene film is denoted as G-70.

[0062] (2) Mixing and pressing of composite phase change materials: Same as in Example 1.

[0063] (3) Hot pressing composite molding: The only difference from Example 1 is that G-10 is replaced with G-70.

[0064] Example 4 This embodiment provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: The only difference from Example 1 is that the total area of ​​the through holes accounts for 90% of the total area of ​​the graphene film, and the resulting porous graphene film is denoted as G-90.

[0065] (2) Mixing and pressing of composite phase change materials: Same as in Example 1.

[0066] (3) Hot pressing composite molding: The only difference from Example 1 is that G-10 is replaced with G-90.

[0067] Example 5 This embodiment provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0068] (2) Mixing and tableting of phase change composite materials: The only difference from Example 1 is that antioxidants and coupling agents are not added.

[0069] (3) Hot pressing composite molding: Same as in Example 1.

[0070] Comparative Example 1 (Pure Composite Phase Change Material) This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: The PCM-0.25 prepared in Example 1 was placed in a flatbed hot press and kept at 80 ℃ and 0.3 MPa for 8 minutes to obtain a pure phase change sheet without a skeleton support, i.e., a phase change thermally conductive interface material.

[0071] Comparative Example 2 (Pure Graphene Film) This comparative example directly uses an unperforated, uncomposite graphene film with a thickness of 250 μm as the interface material.

[0072] Comparative Example 3 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0073] (2) Mixing and tableting of composite phase change materials: The only difference from Example 1 is that “2 g of polyisobutylene (viscosity of 20000 mPa·s)” is replaced with “2 g of polyisobutylene (viscosity of 9000 mPa·s)”.

[0074] (3) Hot pressing composite molding: Same as in Example 1.

[0075] Comparative Example 4 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0076] (2) Mixing and tableting of composite phase change materials: The only difference from Example 1 is that “2 g of polyisobutylene (viscosity of 20000 mPa·s)” is replaced with “2 g of dimethylsiloxane (viscosity of 600 mPa·s)”.

[0077] (3) Hot pressing composite molding: Same as in Example 1.

[0078] Comparative Example 5 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0079] (2) Mixing and tableting of composite phase change materials: The only difference from Example 1 is that 2 g of paraffin (phase change point of 50°C), 0.5 g of polyisobutylene (viscosity of 20000 mPa·s), 86.5 g of aluminum powder (particle size of 3 μm), 10 g of zinc oxide (particle size of 4 μm), 0.5 g of antioxidant 1010 and 0.5 g of KH-550 silane coupling agent are added to a double planetary mixer.

[0080] (3) Hot pressing composite molding: Same as in Example 1.

[0081] Comparative Example 6 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0082] (2) Mixing and tableting of phase change composite materials: The only difference from Example 1 is that 10 g of paraffin (phase change temperature of 50°C), 2 g of polyisobutylene (viscosity of 20000 mPa·s), 77 g of aluminum powder (particle size of 3 μm), 10 g of zinc oxide (particle size of 4 μm), 0.5 g of antioxidant 1010 and 0.5 g of KH-550 silane coupling agent are added to a double planetary mixer.

[0083] (3) Hot pressing composite molding: Same as in Example 1.

[0084] Comparative Example 7 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0085] (2) Mixing and tableting of phase change composite materials: The only difference from Example 1 is that 7 g of paraffin (phase change temperature of 50°C), 7 g of polyisobutylene (viscosity of 20000 mPa·s), 70 g of aluminum powder (particle size of 3 μm), 15 g of zinc oxide (particle size of 4 μm), 0.5 g of antioxidant 1010 and 0.5 g of KH-550 silane coupling agent are added to a double planetary mixer.

[0086] (3) Hot pressing composite molding: Same as in Example 1.

[0087] Comparative Example 8 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: Same as in Example 1.

[0088] (2) Mixing and tableting of phase change composite materials: The only difference from Example 1 is that “aluminum powder with a particle size of 4 μm” is replaced with “aluminum powder with a particle size of 10 μm”.

[0089] (3) Hot pressing composite molding: Same as in Example 1.

[0090] Comparative Example 9 This comparative example provides a method for preparing a phase change thermally conductive interface material, including the following steps: (1) Laser drilling of graphene film: The only difference from Example 1 is that the density of the self-supporting graphene film is 0.05 g / cm³ and the thermal diffusivity is 500 mm² / s. The other parameters are the same as those in Example 1.

[0091] (2) Mixing and pressing of composite phase change materials: Same as in Example 1.

[0092] (3) Hot pressing composite molding: Same as in Example 1.

[0093] The interface materials in the above embodiments and comparative examples were tested for thermal resistance, tensile properties, and anti-pumping properties. The specific methods are as follows: Thermal conductivity: Thermal resistance was tested according to ASTM D 5470 standard; Tensile strength: Tensile strength was tested according to ASTM D 412 standard; Pump-out resistance: Cut the sample into 20 mm × 20 mm square pieces and place them in a 60℃ constant temperature oven for 168 hours (7 days), observing the surface condition periodically. After the test, rate according to the following standards: Grade A: Surface dry, no visible liquid phase seepage; Grade B: Slightly moist in some areas, but without droplets or dripping; Grade C: Obvious oozing, with droplets accumulating or flowing along the edges.

[0094] The results are shown in Table 1.

[0095] Table 1. Test Results

[0096] The test results above show that the phase change thermal interface material provided by the present invention has good thermal conductivity and good anti-pumping performance.

[0097] In summary, this invention provides a phase change thermally conductive interface material and its preparation method. This phase change thermally conductive interface material possesses ultra-low thermal resistance, excellent in-plane thermal diffusion capability, and anti-pumping performance under long-term thermal cycling, making it suitable for reliable heat dissipation in high-power-density electronic devices. Specifically, a three-dimensional confined framework is constructed by laser-drilling a graphene film to form a porous graphene film. A high thermal conductivity composite phase change material is then filled into the porous graphene channels using a hot-pressing method to form the phase change thermally conductive interface material. The porous graphene film provides an efficient in-plane thermal diffusion path, and the composite phase change material perfectly wets the interface, achieving a thermal resistance as low as 0.043 °C·cm. 2 / W (40 psi), the pores of the porous graphene film physically confine the composite phase change material, enhancing cohesion and viscoelasticity when combined with high-viscosity polyolefin resin. Simultaneously, aluminum powder with a particle size of 3-5 μm and zinc oxide with a particle size of 1-5 μm are incorporated to construct a dense thermally conductive network. These three elements work synergistically to further suppress flow and enhance anti-pumping performance without significantly sacrificing wettability, thereby greatly improving the dimensional stability of the material during thermal cycling. Furthermore, the mechanical properties of the phase change thermally conductive interface material are adjustable; by controlling the proportion of perforated area, a balance can be struck between thermal resistance and tensile strength.

[0098] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A phase change thermally conductive interface material, characterized in that, It includes a porous graphene film and a composite phase change material filling the pores of the porous graphene film; The composite phase change material comprises the following components by mass: Paraffin wax 1-5 parts, liquid polyolefin resin 1-5 parts, and thermally conductive filler 85-105 parts; The viscosity of the liquid polyolefin resin at 25°C is 10000~50000 mPa·s; The particle size of the thermally conductive filler is 1~5 μm.

2. The phase change thermally conductive interface material according to claim 1, characterized in that, The phase transition temperature of the paraffin is 45–60°C; and / or, The viscosity of the liquid polyolefin resin at 25°C is 20000~50000 mPa·s; and / or, The thermally conductive filler comprises 85-105 parts, including 80-90 parts of a first filler and 5-15 parts of a second filler; the particle size of the first filler is 3-5 μm, and the particle size of the second filler is 1-5 μm; the first filler includes at least one of alumina, aluminum nitride, diamond, boron nitride, and aluminum powder; and the second filler includes zinc oxide.

3. The phase change thermally conductive interface material according to claim 2, characterized in that, The second filler also includes at least one of an antioxidant and a coupling agent; The antioxidants include at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants; The coupling agent includes at least one of silane coupling agents and titanate coupling agents.

4. The phase change thermally conductive interface material according to claim 1, characterized in that, The liquid polyolefin resin includes at least one selected from polybutene, hydrogenated polybutadiene, polyisobutylene, polyα-olefin, and hydrogenated polyisoprene; and / or, The thickness of the porous graphene film is 20~500 μm; and / or, The thermal diffusivity of the porous graphene film is greater than or equal to 500 mm. 2 / s; and / or, The porous graphene film has a density of 0.07~0.18 g / cm³. 3 .

5. The phase change thermally conductive interface material according to claim 1, characterized in that, The pores in the porous graphene film are through-holes in the thickness direction, and the through-holes are distributed in an array; in the planar direction of the porous graphene film, the total area of ​​the through-holes accounts for 10% to 95% of the area of ​​the porous graphene film.

6. The phase change thermally conductive interface material according to claim 5, characterized in that, The diameter of the through hole is 20~100 μm.

7. A method for preparing a phase change thermally conductive interface material according to any one of claims 1-6, characterized in that, Includes the following steps: Provide porous graphene membranes; The composite phase change material is prepared into a flexible sheet, which is then placed on the surface of the porous graphene film and hot-pressed to melt and fill the pores of the porous graphene film, thereby obtaining the phase change thermally conductive interface material.

8. The preparation method according to claim 7, characterized in that, The process parameters used in the hot pressing are as follows: The temperature is 60~100 ℃, the pressure is 0.1~1 MPa, and the time is 5~10 min.

9. The preparation method according to claim 7, characterized in that, The dimensions of the flexible sheet are the same as those of the porous graphene film. Composite phase change materials are prepared into flexible sheets by hot pressing.

10. The preparation method according to claim 7, characterized in that, The method for preparing the porous graphene membrane includes the following steps: Provide graphene films; Laser drilling is performed on the graphene film to form an array of through holes in the plane of the graphene film, thus obtaining the porous graphene film.

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