Phase change thermosetting resin, preparation method therefor, and heat dissipation composite comprising same

Abstract

The present invention provides a method for preparing a phase change thermosetting resin for a heat dissipation composite, and a phase change thermosetting resin for a heat dissipation composite, which is prepared using same, the method comprising the steps of: mixing and melting an epoxy resin and a phase change compound so as to prepare a melted mixture; and adding a curing agent to the melted mixture and reacting same so as to induce an esterification bond between the thermosetting epoxy resin and the phase change compound. The phase change thermosetting resin is used as a matrix of various heat dissipation composites, and thus can improve excellent mechanical properties and heat dissipation properties of the composites.

Description

Phase change thermosetting resin, method for producing same, and heat dissipating composite comprising same

[0001] The present invention relates to a technology for manufacturing a phase-change thermosetting resin that can stably store and release heat energy by utilizing the latent heat of a phase-change material during a phase change, and can be used in heat-dissipating composite materials, etc.

[0002] Recently, with the increasing demand for eco-friendly energy, such as carbon reduction, research is being conducted to improve energy storage and efficiency. Phase change materials (PCMs) are actively being studied for their application in various fields (e.g., architecture, automobiles, food, textiles, and energy storage systems) due to their characteristic of storing and releasing thermal energy by utilizing the latent heat of the material during phase change. With the increasing electrification of automobiles, they are also attracting attention as materials for thermal control components in future electric vehicles. PCMs utilize phase change with high-capacity heat storage functions to enhance heat dissipation for efficient heat management of moving parts in electronic devices, and they also implement functions that enhance safety through cooling effects in case of abnormal operation.

[0003] Phase change materials (PCMs) have low thermal conductivity and limited storable heat capacity, which limits their practical thermal energy storage efficiency and hinders their industrial application. To address this, research is underway on composite strategies that enhance the latent heat storage (LHS) properties of PCMs by enhancing their thermal conductivity. For these PCMs to be applied to practical products, they must meet various performance requirements driven by advancements in electronic device technology. Among these, key performance attributes, such as high latent heat capacity, high thermal conductivity, and meeting a specific phase transition temperature range, are essential.

[0004] Furthermore, the aforementioned phase change materials have weak mechanical strength, which significantly limits their application range. Therefore, the development of phase change materials with superior strength is essential. In particular, the leakage problem during phase change is a major factor limiting the commercialization of phase change materials. A common method to address this issue involves adding fillers with a porous structure. However, this method is still insufficient for application to phase change composites due to the low thermal conductivity of porous fillers.

[0005] The present invention is an invention that has been sought in recognition of the problems and needs described above, and aims to provide a method for producing a phase change thermosetting resin that has excellent mechanical strength, can significantly increase the latent heat of a phase change material, and can further solve the problem of liquid leakage of the phase change material.

[0006] In addition, the present invention aims to provide a phase change heat-curable resin having excellent mechanical strength and heat buffering properties, manufactured by the above method.

[0007] Furthermore, the present invention aims to provide a heat dissipation composite having excellent heat dissipation properties by including the thermosetting resin and an excellent thermally conductive filler.

[0008] A method for producing a phase-change thermosetting resin for a heat-dissipating composite material according to one embodiment of the present invention comprises the steps of mixing and melting an epoxy resin and a phase-change compound to prepare a molten mixture; and the step of adding a curing agent to the molten mixture and reacting it to induce an esterification bond between the thermosetting epoxy resin and the phase-change compound.

[0009] The above phase change compound comprises erythritol.

[0010] The above curing agent may include a compound of the following chemical formula (1).

[0011]

[0012]

[0013] A phase change thermosetting resin for a heat-dissipating composite material according to one embodiment of the present invention is manufactured by the above-described method, and has a characteristic that liquid leakage does not occur up to a temperature of 190°C to 210°C, which exceeds the melting point of the phase change compound.

[0014] A heat dissipation composite according to one embodiment of the present invention comprises a first filler obtained by freeze-drying and carbonizing a mixture of boron nitride and cellulose nanofibers; and the phase-change thermosetting resin described above.

[0015] A heat dissipation composite according to another embodiment of the present invention comprises a second filler obtained by freeze-drying and carbonizing a mixture of aluminum nitride and cellulose nanofibers; and the phase-change thermosetting resin described above.

[0016] By chemically introducing BPA, a thermosetting resin, into ET molecules to develop a thermosetting phase change material, the problem of liquid leakage occurring at the melting point of ET can be solved, mechanical strength can be significantly improved, and latent heat loss can be minimized.

[0017] In addition, as a method to solve the liquid leakage of phase change materials in the existing composite process, a high thermal conductivity heat dissipation composite of 10 W / mK can be manufactured by introducing a high thermal conductivity boron nitride-based filler instead of using a low thermal conductivity porous structure filler.

[0018] Figure 1 is a conceptual diagram for conceptually explaining a method for manufacturing a phase-change thermosetting resin for a heat-dissipating composite material according to one embodiment of the present invention.

[0019] FIG. 2 is a graph showing the results of Fourier transform infrared spectroscopy (a) and differential scanning calorimetry (b) before and after synthesis of a phase change thermosetting resin according to one embodiment of the present invention.

[0020] Figure 3 is a scanning electron microscope photograph of a cross-section of a phase change thermosetting resin before (a, b) and after (c, d) reaction according to one embodiment of the present invention.

[0021] Figure 4 is a graph comparing mechanical properties and latent heat characteristics according to the reaction ratio of erythritol and epoxy resin.

[0022] Figure 5 is a photograph showing the results of a liquid leak test for erythritol and epoxy resin-introduced erythritol.

[0023] FIG. 6 is a conceptual diagram for conceptually explaining a method for manufacturing a heat dissipation composite according to one embodiment of the present invention.

[0024] Hereinafter, with reference to the attached drawings, a method for manufacturing a phase-change thermosetting resin for a heat-dissipating composite material according to an embodiment of the present invention and a phase-change thermosetting resin manufactured thereby will be described in detail. In addition, an embodiment of a heat-dissipating composite including the phase-change thermosetting resin will also be described. The following descriptions are exemplary descriptions for explaining specific aspects of the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited by the following descriptions. The technical idea of ​​the present invention can be interpreted and limited only by the claims described below.

[0025] Meanwhile, we aim to promote a thorough understanding of the invention by excluding conventional table of contents such as "Examples" and appropriately including contents corresponding to "Examples" in the explanation without any special format.

[0026] The present invention provides a solution for applying a compound having phase change properties, such as erythritol, to a heat-dissipating composite material. By introducing a thermosetting resin into the phase change compound, the functionality of the phase change compound is expressed, while resolving problems such as mechanical properties and liquid leakage.

[0027] Figure 1 is a conceptual diagram for conceptually explaining a method for manufacturing a phase-change thermosetting resin for a heat-dissipating composite material according to one embodiment of the present invention.

[0028] Referring to FIG. 1, the method for manufacturing a phase-change thermosetting resin for a heat-dissipating composite material of the present embodiment includes the steps of mixing and melting a thermosetting resin, an epoxy resin, and a phase-change compound to prepare a molten mixture; and the step of adding a curing agent to the molten mixture and reacting the mixture to induce an esterification bond between the thermosetting epoxy resin and the phase-change compound.

[0029] In this embodiment, the thermosetting resin includes an epoxy resin, and the phase change compound includes erythritol (ET).

[0030] The above erythritol was selected as the phase change compound of the present embodiment due to its high latent heat (390 J / g) and abundant hydroxyl groups (-OH). However, in order to improve the low mechanical properties of ET and the liquid leakage problem occurring at the melting point, a phase change thermosetting resin (ETBPA) is manufactured by chemically introducing a thermosetting material, epoxy resin (Bisphenol A (YD-128), hereinafter referred to as BPA). When BPA is linked to the molecular structure of ET and forms a cross-linking structure through a curing reaction, it prevents the liquid from leaking out during the phase change of ET and can significantly improve the mechanical properties.

[0031] Referring back to Figure 1, when BPA and ET are mixed and melted, a curing agent is added thereto to cause a reaction, thereby forming an ester bond between the BPA and ET. The phase-change thermosetting resin produced after the reaction includes ET, a phase-change compound partially attached to the chain of the epoxy resin, as shown in Figure 1. Through heating and cooling, the ET can efficiently manage latent heat while undergoing a phase change into crystallized ET or molten ET.

[0032] In this process, ET, which has been transformed into a liquid phase through heating, can be stably confined within the matrix without melting and leaking due to ester bonding with the epoxy resin.

[0033] Meanwhile, in this embodiment, a compound of the following chemical formula (1) is used as a curing agent for the crosslinking reaction of BPA, which is the thermosetting resin.

[0034] [Chemical Formula 1]

[0035]

[0036]

[0037] [Manufacturing of ETBPA]

[0038] To solve the layer separation problem that occurs when simply mixing ET and BPA, BPA (hereinafter referred to as ETBPA) with abundant hydroxyl groups of ET was manufactured through esterification of ET and BPA. First, 1.5 g and 1 g of ET and BPA, respectively, were mixed at a molar ratio of 0.8:1 (mass ratio = 1.5:1) and slowly stirred at 150℃ until completely dissolved. To the completely dissolved mixture, 0.33 g of a curing agent (D-230) corresponding to a 1:1 equivalent ratio to BPA was added and reacted while slowly stirring at 150℃ until the mixture produced smoke and turned transparent yellow, manufacturing ETBPA. The prepared ETBPA mixture was transferred to a Teflon mold and heat-cured at 150℃ for 2 hours and 30 minutes to manufacture ETBPA, a phase change polymer material with enhanced mechanical properties.

[0039] [Experimental Evaluation]

[0040] 1. Synthesis confirmation

[0041] (1) Spectroscopic and thermal behavior analysis

[0042] FIG. 2 is a graph showing the results of Fourier transform infrared spectroscopy (a) and differential scanning calorimetry (b) before and after synthesis of a phase change thermosetting resin according to one embodiment of the present invention.

[0043] Referring to Figure 2(a), the epoxy group of BPA before reaction (COC, 912 cm -1 ) is greatly reduced after ETBPA synthesis, and a new ester group (C=O, 1738 cm -1 ) was confirmed to be formed. This indicates that esterification was successful. In addition, the abundant hydroxyl groups of ET (-OH, 3200 cm -1 ) was confirmed to observe a broad hydroxyl peak in ETBPA. Therefore, it was confirmed that ETBPA was successfully synthesized.

[0044] Meanwhile, referring to Fig. 2(b), as a result of DSC analysis to confirm the change in thermal behavior of the material according to the ETBPA manufacturing process, ET and BPA before the reaction exhibited endothermic reactions at around 125°C and 40°C, respectively, whereas after ETBPA synthesis, the hydroxyl group of ET, which causes hydrogen bonds, was reduced by esterification reaction, weakening the intermolecular force and reducing the endothermic reaction range to 120°C. This confirmed that ETBPA was formed through chemical bonding.

[0045] (2) Cross-sectional analysis

[0046] Figure 3 is a scanning electron microscope photograph of a cross-section of a phase change thermosetting resin before (a, b) and after (c, d) reaction according to one embodiment of the present invention.

[0047] Referring to Figure 3, in the case of ET / BPA cured after simple mixing of ET and BPA (a, b), layer separation of ET and BPA clearly occurred. In contrast, cross-sectional images of ETBPA after esterification (c, d) confirmed that a uniform single phase was maintained through chemical bonding. This confirmed the successful synthesis of ETBPA.

[0048] 2. Physical property analysis

[0049] Figure 4 is a graph comparing mechanical properties and latent heat characteristics according to the reaction ratio of erythritol and epoxy resin. Meanwhile, the mechanical properties and latent heat characteristics results are shown in Table 1 below.

[0050] Referring to Fig. 4, mechanical properties (tensile strength, elongation) and latent heat were measured according to the mixing ratio of the manufactured ETBPA. The analysis results confirmed that both tensile strength and elongation in all samples were improved by more than three times compared to pure ET in terms of mechanical properties. Since latent heat is the most important characteristic in phase change materials, based on the measurement results, ETBPA manufactured at a ratio of 1.5:1 (ET: BPA) that could maximize latent heat characteristics was used as the final material.

[0051] Latent heat and mechanical properties according to ETBPA ratio Ratio (ET:BPA) Tensile strength (MPa) Tensile strain (%) Latent heat (J / g) 1:00.8 3.33 390 1:14.4 15.6 1137 1.3:12.9 7.96 161.5 1.5:12.7 3 11.58 203.8

[0052] 3. Leakage Test Figure 5 is a photograph showing the results of a liquid leak test for erythritol and epoxy resin-introduced erythritol.

[0053] Referring to Figure 5, at a mass ratio of 1.5:1 (ET:BPA), no liquid leakage occurred up to 200°C (±10°C), which is higher than the melting point of ET (around 120°C). However, in the case of pure ET, some liquefaction began to be visible at 130°C, and at 150°C, it was confirmed that it completely turned into a liquid and its shape collapsed.

[0054] Through repeated experiments, it was confirmed that the phase change thermosetting resin manufactured by including ET as a phase change compound according to one embodiment of the present invention did not cause liquid leakage at temperatures ranging from 190°C to 210°C.

[0055] The phase change thermosetting resin for heat-generating composites manufactured as described above can be utilized on its own, but can also be manufactured into excellent heat-generating composites through mixing and molding with a thermally conductive filler that can exhibit synergy.

[0056] In this embodiment, two types of heat dissipation composites are presented as follows.

[0057] FIG. 6 is a conceptual diagram for conceptually explaining a method for manufacturing a heat dissipation composite according to one embodiment of the present invention.

[0058] Referring to FIG. 6, in the present embodiment, the heat dissipation composite uses ETBPA as a matrix and includes (1) BNCNF / BN or (2) AINCNF / AIN as a filler.

[0059] BNCNF fillers are produced by mixing boron nitride (BN) and cellulose nanofibers (CNF) in distilled water, freeze-drying the mixture, and then carbonizing the resulting product. The BNCNF filler can be mixed with BN and prepared ETBPA, and then manufactured into a heat-dissipating composite through processes such as hot pressing. However, it should be noted that various molding methods, such as injection molding, can be applied in addition to hot pressing.

[0060] Meanwhile, AINCNF filler is manufactured using a similar method. It involves mixing aluminum nitride (AIN) and cellulose nanofibers (CNF) in distilled water, freeze-drying the mixture, and then carbonizing it. The AINCNF filler can be manufactured into a heat-dissipating composite by mixing it with AIN and prepared ETBPA, and then hot pressing or other processes.

[0061] The heat dissipation composite manufactured as above can exhibit not only excellent mechanical properties but also a heat buffering effect due to stable phase change characteristics and high thermal conductivity due to the filler.

[0062] [Evaluation of composite thermal conductivity properties]

[0063] As described above, a heat-dissipating composite was manufactured by adding a boron nitride-based high-heat-dissipating filler (BNCNF / BN) to ETBPA. To confirm the vertical thermal conductivity characteristics of the composite, the thermal conductivity was measured using laser flash analysis at room temperature (25°C). The results are shown in Table 2 below. The measured vertical thermal conductivity result showed a thermal conductivity of 13.09 at a filler loading of 60 wt%, which is superior to previous studies on heat-dissipating composites based on conventional phase change materials.

[0064] Comparison of thermal conductivity and latent heat properties of phase change composites Composite type wt% Thermal conductivity (W / mK) Latent heat (J / g) ETBPA / BNCNF / BN-1 100.64 190.4 ETBPA / BNCNF / BN-2 201.26 184.3 ETBPA / BNCNF / BN-3 302.33 178.6 ETBPA / BNCNF / BN-4 404.11 167.5 ETBPA / BNCNF / BN-5 506.43 157.8 ETBPA / BNCNF / BN-6 6013.09 98.4 ETBPA / BNCNF / BN-7 7010.27 88.3 Erythritol / Sep / xGnP (previous study) 440.75 6167.7

Claims

1. A step of preparing a molten mixture by mixing and melting an epoxy resin and a phase change compound; and Comprising a step of adding a hardener to the molten mixture and reacting it to induce an esterification bond of the thermosetting epoxy resin and the phase change compound. Method for producing a phase-change thermosetting resin for heat-dissipating composite materials.

2. In paragraph 1, A method for producing a phase change thermosetting resin for a heat-dissipating composite material, characterized in that the phase change compound comprises erythritol.

3. In paragraph 1, A method for producing a phase-change thermosetting resin for a heat-dissipating composite material, characterized in that the curing agent comprises a compound of the following chemical formula (1). (1) 4. Manufactured by the method of paragraph 2, Characterized in that no liquid leakage occurs up to a temperature of 190°C to 210°C, which exceeds the melting point of the phase change compound. Phase change thermosetting resin for heat dissipating composite materials.

5. A first filler obtained by freeze-drying and carbonizing a mixture of boron nitride and cellulose nanofibers; and Including the phase change thermosetting resin of Article 4, Heat dissipation composite.

6. A second filler obtained by freeze-drying and carbonizing a mixture of aluminum nitride and cellulose nanofibers; and Including the phase change thermosetting resin of Article 4, Heat dissipation composite.

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