Heat-conducting phase change material as well as preparation method and application thereof

Abstract

The invention discloses a heat-conducting phase-change material as well as a preparation method and application thereof, and belongs to the technical field of heat-conducting materials. The heat-conducting phase-change material comprises the following components in percentage by weight: 2-20% of elastomer, 1-10% of organic phase-change material, 80-95% of heat-conducting filler, 0.1-1% of coupling agent and the balance of solvent. The preparation method comprises the following steps: heating and dissolving the elastomer, the organic phase-change material and the solvent, cooling, adding the heat-conducting filler and the coupling agent, and uniformly mixing. Through collaborative design of the components and the proportion, the material has high heat conductivity coefficient, low heat resistance and proper paste viscosity, is particularly suitable for a silk-screen printing process and serves as a heat conduction interface material in heat dissipation of electronic devices, can form a thin and uniform interface layer, and is stable in form, free of precipitation risk and high in reliability at the phase change temperature.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, specifically relating to a thermally conductive phase change material, its preparation method and application, and is particularly suitable for heat dissipation interface materials of electronic devices using screen printing processes. Background Technology

[0002] As electronic devices evolve towards higher integration and higher power, the heat generated during operation can easily cause device temperatures to rise, thus affecting performance and lifespan. Therefore, the development of efficient heat dissipation materials is crucial. Thermally conductive phase change materials, which can adjust their morphology with temperature changes and fill gaps in heat dissipation interfaces, have become one of the commonly used materials in the field of electronic heat dissipation.

[0003] Existing thermally conductive phase change materials suffer from problems such as easy pumping out and drying out, failing to maintain an effective heat dissipation interface. Furthermore, single phase change materials tend to liquefy at the phase change temperature, leading to oil seepage or migration, affecting device stability. In addition, some existing high thermal conductivity filler composite materials often struggle to simultaneously achieve high thermal conductivity, suitable processing viscosity, and long-term morphological stability. Chinese invention patent application CN118667519A discloses a sandwich-structured flexible flame-retardant insulating phase change material, its preparation method, and its application. This composite structure, employing a "phase change thermal storage inner core + flexible flame-retardant outer shell," aims to simultaneously achieve flame retardancy (UL-94V0 rating), electrical insulation, leak prevention, and a certain degree of flexibility. However, its thermal conductivity is low, making it difficult to meet the requirements for efficient heat dissipation; the structure is heavy and the process is complex, requiring multiple preparation steps and long curing times, making it unsuitable for precision thin-layer coating processes such as screen printing.

[0004] Therefore, developing a thermally conductive interface material that combines high thermal conductivity, excellent screen printing processability, morphological stability at phase change temperature, and no risk of precipitation is of great practical significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a thermally conductive phase change material, its preparation method, and its applications. This thermally conductive phase change material has high thermal conductivity, low thermal resistance, stable morphology, and is suitable for screen printing processes.

[0006] To achieve this objective, the present invention employs the following technical solution: In a first aspect, the present invention provides a thermally conductive phase change material, comprising the following components by weight percentage: 2% to 20% elastomer, 1% to 10% organic phase change material, 80% to 95% thermally conductive filler, 0.1% to 1% coupling agent, and the balance being solvent; The thermally conductive filler is a combination of alumina and zinc oxide, wherein the weight ratio of alumina to zinc oxide is (15-25):1.

[0007] This invention utilizes a precise ratio of alumina to zinc oxide (15-25):1 in its thermally conductive filler to achieve optimal synergy in thermal conductivity, dispersion stability, and process compatibility. Alumina, as the core thermally conductive framework, dominates the filler due to its high thermal conductivity, stable chemical properties, and low cost, constructing a continuous macroscopic thermal conductivity pathway. Zinc oxide acts as a dispersing thermal conductivity aid; although its thermal conductivity is slightly lower, its strong surface polarity provides both gap filling and anti-agglomeration functions. The 15-25:1 ratio of alumina to zinc oxide avoids encroaching on the alumina stacking space while precisely filling the "thermal conductivity blind spots" between alumina particles, eliminating air gaps and making the thermally conductive network denser. Simultaneously, after reacting with the coupling agent, zinc oxide "anchors" itself to the alumina surface, creating a steric hindrance effect that prevents alumina agglomeration.

[0008] Optionally, the elastomer includes one or more of silicone, SEBS, trans polyoctene, EVA, nitrile rubber, and TPI.

[0009] Further optionally, the elastomer comprises silicone and trans-polyoctene, wherein the weight ratio of silicone to trans-polyoctene is (20~30):1.

[0010] The elastomer of this invention uses a weight ratio of silicone to trans-polyoctene of 20-30:1, achieving a precise balance between the "rigid support" and "dynamic adaptation" of the elastomer network. At this ratio, silicone acts as a continuous phase, forming a stable three-dimensional network framework, primarily responsible for locking in the phase change material and providing the system's basic elasticity and mechanical strength. A small amount of trans-polyoctene, as a functional component, is uniformly dispersed within the silicone network; its molecular chain segments possess unique shape memory properties and higher compatibility. This ratio range ensures that the amount of trans-polyoctene is sufficient to exert its unique phase-locking function, while avoiding excessive addition that could adversely alter the system's viscoelasticity, thus guaranteeing that the material always maintains a stable paste-like form suitable for screen printing.

[0011] Optionally, the organic phase change material includes one or more of paraffin wax, microcrystalline wax, tetradecanoic acid ester, rosin paste, n-octadecane, and n-docosahexadecane.

[0012] Optionally, the coupling agent includes one or more of KH560, KH570, KH550, tetraethyl orthosilicate, KRTTS, and dodecyltrimethoxysilane.

[0013] Optionally, the solvent includes one or more of ethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, and diethylene glycol butyl ether.

[0014] Secondly, the present invention provides a method for preparing the thermally conductive phase change material as described above, comprising the following steps: (1) Mix the elastomer, organic phase change material and solvent, heat to 70~90℃, and stir until completely dissolved to obtain a mixed solution; (2) After cooling the mixed solution to room temperature, add thermally conductive filler and coupling agent, mix and stir evenly to obtain the thermally conductive phase change material.

[0015] The stirring time in step (1) is 2 to 4 hours, and the stirring speed is 30 to 60 r / min.

[0016] The mixing time in step (2) is 2 to 4 hours, and the stirring speed is 30 to 60 r / min.

[0017] Thirdly, the present invention provides an application of the thermally conductive phase change material as described above, wherein the thermally conductive phase change material is used as a thermally conductive interface material for screen printing in the heat dissipation of electronic devices.

[0018] Beneficial effects 1. The thermally conductive filler of this invention uses alumina and zinc oxide in a ratio of (15-25):1. This utilizes the high thermal conductivity of alumina and the dispersion aided by zinc oxide to prevent filler agglomeration and effectively improve the thermal conductivity.

[0019] 2. The synergistic ratio of the elastomer and organic phase change material in this invention maintains the material in a stable paste state, and there is no oil seepage, drying or pumping out during use.

[0020] 3. The material of this invention has good rheological properties, and an extremely thin and uniform interface layer can be formed by screen printing, which further reduces thermal resistance.

[0021] 4. The thermally conductive phase change material of this invention is particularly suitable for electronic devices with high requirements for heat dissipation and reliability. As a highly efficient thermal interface material, it can significantly improve the heat dissipation efficiency and service life of the device. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified, the raw materials involved in the embodiments are all commercially available conventional products.

[0023] Example Examples 1-4 and Comparative Examples 1-7 The first aspect of this invention, including Examples 1-4 and Comparative Examples 1-7, provides a thermally conductive phase change material, the formulation of which is shown in Table 1 by weight percentage.

[0024]

[0025] The first aspect of this invention, as provided in Examples 1-4 and Comparative Examples 1-7, offers a method for preparing a thermally conductive phase change material, comprising the following steps: (1) Add the elastomer, organic phase change material and solvent to a sealed container according to the ratio, and stir at 80℃ and 40r / min for 2h until completely dissolved to obtain a mixed solution; (2) After cooling the mixture solution to 25°C, add the thermally conductive filler and coupling agent, and continue stirring at 55 r / min for 3 hours until the mixture is uniform. Then discharge the mixture to obtain the final product.

[0026] Performance testing The thermally conductive phase change materials prepared in Examples 1-4 and Comparative Examples 1-7 were subjected to performance tests. The test methods and standards are as follows: Thermal conductivity, thermal resistance, and adhesive layer thickness: refer to ASTM D5470 standard.

[0027] Morphological observation: Visual assessment at room temperature (25℃).

[0028] The test results for each embodiment and comparative example are shown in Table 2 below: Table 2

[0029] As shown in Table 2, the thermally conductive phase change materials prepared in Examples 1-4 of this invention all exhibit high thermal conductivity (>3.5 W / m·K), low thermal resistance (≤0.01 °C·in² / W), and good screen printing processability.

[0030] In particular, Example 4, with its optimized ratio of silica gel and trans-polyoctene compounded, mixed with organic phase change materials and a specific solvent, achieved excellent comprehensive performance, with no precipitation at the phase change temperature and high long-term reliability. Comparative Example 4, due to the fact that the elastomer is only silicone, lacks the synergistic locking effect with the organic phase change material, resulting in high-temperature precipitation.

[0031] Comparative Example 5 had an excessively high SEBS ratio, resulting in excessive viscosity and poor processability.

[0032] Comparative Examples 6 and 7 used unsuitable solvents, which resulted in odor problems and changes in form, respectively, leading to a loss of screen printability.

[0033] Comparative Examples 1-3, by changing the type and proportion of thermally conductive fillers, although the thermal conductivity of some samples was still acceptable, either led to a decrease in overall thermal conductivity or damaged the leveling properties of the material, resulting in an increase in the thickness of the adhesive layer. This verified the importance of high alumina content and specific alumina / zinc oxide ratio in this invention. In summary, this invention has successfully obtained a thermally conductive phase change material for screen printing with excellent comprehensive performance through the synergistic effect of specific components and their proportions.

Claims

1. A thermally conductive phase change material, characterized in that, By weight percentage, including the following components: elastomer 2%~20%, organic phase change material 1%~10%, heat-conducting filler 80%~95%, coupling agent 0.1%~1%, the balance is solvent; The heat-conducting filler is a combination of aluminum oxide and zinc oxide, wherein the weight ratio of the aluminum oxide to the zinc oxide is (15-25):

1.

2. The thermally conductive phase change material of claim 1, wherein, The elastomer includes one or more of silica gel, SEBS, trans-polyoctenamer, EVA, nitrile rubber or TPI.

3. The thermally conductive phase change material of claim 1, wherein, The elastomer includes silica gel and trans-polyoctenamer, and the weight ratio of the silica gel to the trans-polyoctenamer is (20~30):

1.

4. The thermally conductive phase change material of claim 1, wherein, The organic phase change material includes one or more of paraffin wax, microcrystalline wax, octadecanoic acid tetradecyl ester, rosin paste, n-octadecane or n-docosane.

5. The thermally conductive phase change material of claim 1, wherein, The coupling agent includes one or more of KH560, KH570, KH550, ethyl orthosilicate, KRTTS or dodecyl trimethoxysilane.

6. The thermally conductive phase change material of claim 1, wherein, The solvent includes one or more of ethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate or diethylene glycol butyl ether.

7. A method for producing a thermally conductive phase change material as claimed in any one of claims 1-6, characterized in that The method includes the following steps: (1) mixing the elastomer, the organic phase change material and the solvent, heating to 70~90℃, stirring until completely dissolved to obtain a mixed solution; (2) after the mixed solution is cooled to room temperature, the heat-conducting filler and the coupling agent are added and mixed and stirred uniformly to obtain the heat-conducting phase change material.

8. The method of claim 7, wherein, In step (1), the stirring time is 2~4h, and the stirring speed is 30~60r / min.

9. The preparation method according to claim 7, characterized in that, In step (2), the mixing and stirring time is 2~4h, and the stirring speed is 30~60r / min.

10. Use of a thermally conductive phase change material as claimed in any one of claims 1-6, characterized in that, The heat-conducting phase change material is applied as a heat-conducting interface material for screen printing in electronic device heat dissipation.

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