Method for surface modification of alumina using silane coupling agent, thermally conductive filler including aluminum oxide having its surface modified thereby, and heat-dissipating material including the same

Abstract

The present invention relates to a method for surface modification of alumina using a silane coupling agent, a thermally conductive filler comprising alumina whose surface is modified according to this method, and a heat dissipation material comprising the same. More specifically, the invention relates to a method for modifying the surface of alumina using a silane coupling agent to improve dispersion power, a thermally conductive filler comprising two types of surface-modified alumina of different sizes with improved thermal conductivity, and a heat dissipation material comprising the same.

Description

Technology Field

[0001] The present invention relates to a method for surface modification of alumina using a silane coupling agent, a thermally conductive filler comprising alumina whose surface is modified according to this method, and a heat dissipation material comprising the same. More specifically, the invention relates to a method for modifying the surface of alumina using a silane coupling agent to improve dispersion power, a thermally conductive filler comprising two types of surface-modified alumina of different sizes with improved thermal conductivity, and a heat dissipation material comprising the same. Background Technology

[0003] The heat generated by the miniaturization and high performance of electronic products used in electric vehicles and electronic materials is causing various problems related to product reliability and lifespan. Therefore, to address this, methods to improve thermal conductivity are being researched in terms of design and materials.

[0004] Thermal interfaces, used to enhance the thermal stability of electric vehicles and electronic materials, are attracting attention as a method to improve thermal conductivity. The aforementioned thermal interface material serves as a boundary region between two materials with different temperatures, transferring heat from the hotter material to the colder material. Thermal interfaces include components such as heat sinks and thermal interface materials (TIMs).

[0005] Electronic devices containing thermal interface materials with high thermal conductivity exhibit better heat transfer, resulting in lower operating temperatures and improved device performance; therefore, thermal interface materials require high thermal conductivity. To increase the thermal conductivity of materials, reinforcing materials—such as ceramic fillers like silicon carbide (SiC), aluminum nitride (Al), and alumina (Al2O3)—are added to the matrix material.

[0006] Heat conduction in non-metallic materials is caused by the vibration of phonons. For these phonon vibrations to occur easily, a heat transfer pathway must be established within the material through the dispersion forces of particles.

[0007] As mentioned above, there is a need to develop a method to improve the dispersion of particles added as reinforcing agents within non-metallic materials used as thermal interface materials to enhance the thermal conductivity of electronic products. The problem to be solved

[0009] The present invention provides a method for surface modification of alumina using a silane coupling agent to improve the dispersion power of alumina in order to solve the above-mentioned problems, a thermally conductive filler comprising surface-modified alumina with improved thermal conductivity through this method, and a heat dissipation material comprising the same.

[0010] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description of the present invention. means of solving the problem

[0012] To achieve the above objective, the present invention provides a method for surface modification of alumina using a silane coupling agent, comprising the steps of: preparing a solvent by mixing distilled water and ethanol; preparing a mixed solution by adding alumina (Al2O3) to the solvent and stirring it once; ultrasonically cleaning the mixed solution; adding a silane coupling agent to the ultrasonically cleaned mixed solution and stirring it twice; adding an aqueous ammonia solution to the mixed solution containing the silane coupling agent and stirring it three times; cooling the solution stirred three times while maintaining stirring; and washing and drying the cooled solution to obtain surface-modified alumina.

[0013] In the present invention, the silane coupling agent is characterized by including an epoxy functional group.

[0014] In the present invention, the silane coupling agent is (3-glycidyloxypropyl)trimethoxysilane ((3-Glycidyloxypropyl)tri-methoxysilane, C9H 20 It is O5Si) and is characterized by being represented by the following [Chemical Formula 1].

[0015] [Chemical Formula 1]

[0016]

[0017] In the present invention, the silane coupling agent is characterized by having a pH of 5 to 7.

[0018] In the present invention, the second stirring step is to stir at 850 to 950 rpm for 20 to 40 minutes at a temperature of 70 to 90 ℃, the third stirring step is to stir at 850 to 950 rpm for 8 to 10 hours at a temperature of 70 to 90 ℃, and the cooling step is characterized by stirring at 850 to 950 rpm for 2 to 4 hours and cooling to room temperature (15 to 25 ℃).

[0019] The present invention aims to provide a thermally conductive filler comprising alumina whose surface has been modified by the above method.

[0020] In the present invention, the surface-modified alumina is characterized by comprising a first-size alumina and a second-size alumina.

[0021] In the present invention, the alumina of the first size has an average size of 6 to 8 μm, and the alumina of the second size has an average size of 3 to 5 μm.

[0022] In the present invention, the surface-modified alumina is characterized by comprising the first size alumina and the second size alumina in a weight ratio of (6 to 5) : 4.

[0023] The present invention aims to provide a heat dissipation material comprising surface-modified alumina, comprising a thermally conductive filler comprising the surface-modified alumina; and a two-component addition-curing silicone. Effects of the invention

[0025] By means of the solution to the above problem, the present invention can provide a method for surface modification of alumina using a silane coupling agent to improve the dispersion power of alumina, a thermally conductive filler comprising surface-modified alumina with improved thermal conductivity through the same, and a heat dissipation material comprising the same.

[0026] In addition, the present invention can provide a heat dissipation material having a simplified structure.

[0027] In addition, the present invention can provide a heat dissipation material that exhibits excellent thermal conductivity and thermal stability simultaneously.

[0028] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0030] FIG. 1 is a drawing showing a heat dissipation material comprising a thermally conductive filler comprising surface-modified alumina according to the present invention. Figure 2 is a diagram showing the results of a dispersion force experiment of alumina particles of an embodiment and a comparative example according to the present invention. Figure 3 is a diagram showing the experimental results of the dispersion power of alumina particles according to pH concentration of an embodiment and a comparative example according to the present invention. Figure 4 is a diagram showing the results of a thermal shock test of an embodiment according to the present invention. Specific details for implementing the invention

[0031] The terms used in this specification have been selected based on currently widely used general terms whenever possible, taking into account their functions in the present invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the corresponding description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention.

[0032] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0033] Numerical ranges include the values ​​defined in the above ranges. All maximum numerical limits given throughout this specification include all lower numerical limits as clearly written. All minimum numerical limits given throughout this specification include all higher numerical limits as clearly written. All numerical limits given throughout this specification will include all better numerical ranges within a wider numerical range, as clearly written.

[0035] Alumina surface modification method using a silane coupling agent

[0036] The present invention relates to a method for modifying the surface of alumina using a silane coupling agent.

[0037] The present invention relates to a method for surface modification of alumina using a silane coupling agent, comprising the steps of: preparing a solvent by mixing distilled water and ethanol; preparing a mixed solution by adding alumina (Al2O3) to the solvent and stirring it once; ultrasonically cleaning the mixed solution; adding a silane coupling agent to the ultrasonically cleaned mixed solution and stirring it twice; adding an aqueous ammonia solution to the mixed solution containing the silane coupling agent and stirring it three times; cooling the solution stirred three times while maintaining stirring; and washing and drying the cooled solution to obtain surface-modified alumina.

[0038] Alumina whose surface has been modified through the surface modification method using the above silane coupling agent may exhibit excellent dispersibility.

[0039] In the present invention, the silane coupling agent may include an epoxy functional group. The epoxy functional group may have a large number of connected C chains, thereby improving dispersibility.

[0040] In the present invention, the silane coupling agent is (3-glycidyloxypropyl)trimethoxysilane ((3-Glycidyloxypropyl)tri-methoxysilane, C9H 20 It is O5Si) and may be represented by the following [Chemical Formula 1].

[0041] [Chemical Formula 1]

[0042]

[0043] In the present invention, the silane coupling agent may have a pH of 5 to 7. If the pH of the silane coupling agent falls outside the above range, a problem may occur in which the dispersibility of the alumina surface-modified by the above method is reduced.

[0044] In the present invention, the second stirring step is stirring at 850 to 950 rpm for 20 to 40 minutes at a temperature of 70 to 90 ℃, the third stirring step is stirring at 850 to 950 rpm for 8 to 10 hours at a temperature of 70 to 90 ℃, and the cooling step may be stirring at 850 to 950 rpm for 2 to 4 hours and cooling to room temperature (15 to 25 ℃).

[0045] If the above stirring step is performed under conditions outside the above range, sufficient surface modification of the alumina does not occur, and as a result, a problem may arise in which the dispersibility of the obtained alumina is reduced.

[0047] Thermally conductive filler containing surface-modified alumina and heat dissipation material containing the same

[0048] The present invention relates to a thermally conductive filler comprising surface-modified alumina.

[0049] The surface-modified alumina may be surface-modified according to a method for surface modification of alumina using a silane coupling agent, comprising the steps of: preparing a solvent by mixing distilled water and ethanol; preparing a mixed solution by adding alumina (Al2O3) to the solvent and stirring once; ultrasonically cleaning the mixed solution; adding a silane coupling agent to the ultrasonically cleaned mixed solution and stirring twice; adding an aqueous ammonia solution to the mixed solution with the added silane coupling agent and stirring three times; cooling the solution stirred three times while maintaining stirring; and washing and drying the cooled solution to obtain surface-modified alumina.

[0050] The thermally conductive filler comprising the surface-modified alumina may exhibit excellent thermal conductivity through the excellent dispersibility of the alumina.

[0051] In the present invention, the surface-modified alumina may comprise a first-size alumina and a second-size alumina. By including the first-size and second-size alumina, the thermal conductivity anisotropy may be reduced, thereby exhibiting excellent thermal conductivity.

[0052] In the present invention, the alumina of the first size may have an average size of 6 to 8 μm, and the alumina of the second size may have an average size of 3 to 5 μm. If the average size of the alumina of the first size and the alumina of the second size falls outside the above range, a problem may occur in which the thermal conductivity of the thermally conductive filler containing them is reduced.

[0053] In the present invention, the surface-modified alumina may comprise the first size alumina and the second size alumina in a weight ratio of (6 to 5) : 4. If the weight ratio of the first size and the second size alumina falls outside the above range, a problem may occur in which the thermal conductivity of the thermally conductive filler containing it is reduced.

[0054] The present invention relates to a heat dissipation material comprising surface-modified alumina, comprising: a thermally conductive filler comprising the surface-modified alumina; and a two-component addition-curing silicone. The heat dissipation material comprising the surface-modified alumina may exhibit excellent thermal conductivity by including a thermally conductive filler that exhibits excellent thermal conductivity, comprising surface-modified alumina that exhibits high dispersibility. The heat dissipation material may contain the thermally conductive filler uniformly throughout the material and may exhibit excellent thermal shock resistance and thermal stability.

[0056] Example of implementation

[0057] Embodiments of the present invention are described in detail below, but it is obvious that the present invention is not limited by the following embodiments.

[0058] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. The embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0060] <Example 1> Surface-modified alumina using a silane coupling agent (GMS)

[0061] Distilled water and ethanol were mixed in a weight ratio of 40:15, and then 1 g of alumina (Al2O3) was added to the mixed solvent and stirred. After treating the stirred solution with an ultrasonic cleaner for 15 minutes, (3-glycidyloxypropyl)trimethoxysilane (C9H), a silane coupling agent with a pH of 6, was used. 20 After adding O5Si (GMS), secondary stirring was performed at 900 rpm for 30 minutes at 80 ℃. 3 mL of an aqueous ammonia solution (NH4OH) was added to the solution that was stirred secondary, and secondary stirring was performed for 9 hours, and the stirring was maintained for 3 hours until the temperature reached room temperature. When the secondary stirring was completed, alumina was obtained from the solvent, and the obtained alumina was washed with ethanol and dried at 60 ℃ for 1 day to produce surface-modified alumina.

[0063] <Example 2> TIM heat dissipation pad containing surface-modified alumina

[0064] Surface-modified alumina with average sizes of 7 μm and 4 μm was prepared in the same manner as in Example 1 above. The alumina with average sizes of 7 μm and 4 μm was mixed using a paste mixer in a weight ratio of 5:4. The mixed alumina was mixed with a two-component addition-curing silicone by stirring. The stirring was carried out for 3 minutes at a process speed of 700 rpm and a rotation speed of 600 rpm, followed by a process speed of 500 rpm and a rotation speed of 450 rpm for 5 minutes. Subsequently, the mixture was cured at 130 ℃ for 30 minutes, and a TIM heat dissipation pad was manufactured using the cured mixture and a release film.

[0066] <Comparative Example 1> Surface-unmodified alumina

[0067] Alumina that had not undergone surface modification was prepared.

[0069] <Comparative Example 2> Alumina surface-modified using a silane coupling agent (AES)

[0070] Silane coupling agent 3-aminoproporyltriethoxysilane ((3-Aminopropyl)tri-ethoxysilane, C9H 23 Surface-modified alumina was prepared in the same manner as in Example 1 above, except that NO3Si, AES) was used.

[0072] <Comparative Example 3> Alumina surface-modified using silane coupling agents (GMS) of different concentrations

[0073] Surface-modified alumina was prepared in the same manner as in Example 1 above, except that the concentration of the silane coupling agent GMS was different. The concentration of the GMS is shown in [Table 1] below.

[0074]

[0075] <Comparative Example 4> TIM thermal pad containing unsurfaced alumina

[0076] A TIM heat dissipation pad containing alumina was manufactured in the same manner as in Example 2 above, except that alumina that had not undergone surface modification was used.

[0078] <Experimental Example 1> Analysis of Alumina Dispersion Forces According to Silane Coupling Agent

[0079] The alumina prepared in Example 1 and Comparative Examples 1 and 2 above was added to distilled water, and the degree of dispersion over time was analyzed, and the results are shown in Figure 2.

[0080] As shown in Figure 2, the surface-unmodified alumina of Comparative Example 1 showed almost no dispersion of particles in distilled water, and it was found that the alumina precipitated after 24 hours, while the surface-modified alumina of Comparative Example 2 showed some dispersion in distilled water, but it was found that it could not maintain a dispersed state after 6 hours.

[0081] On the other hand, the alumina surface-modified with GMS of Example 1 above exhibited high dispersion power in distilled water and was found to maintain a dispersed state even after 24 hours.

[0082] Through the above results, it was confirmed that the alumina surface modified according to the method of surface modification using a silane coupling agent according to the present invention exhibits high dispersion power and can maintain the dispersed state for a long time.

[0084] <Experimental Example 2> Analysis of Alumina Dispersion Forces According to Silane Coupling Agent

[0085] The alumina prepared in Example 1 and Comparative Examples 3-1 to 3-3 was added to distilled water, and the degree of dispersion over time was analyzed, and the results are shown in Figure 3.

[0086] As shown in Fig. 3, the alumina of Comparative Examples 3-1 to 3-3 exhibited high dispersion power in distilled water, but it was found that it failed to maintain a dispersed state after 3 hours. On the other hand, the alumina of Example 1, whose surface was modified with GMS having a pH of 6, exhibited high dispersion power in distilled water and was found to maintain a dispersed state even after 24 hours.

[0087] Through the above results, it was confirmed that the alumina surface modified according to the method of surface modification using a silane coupling agent according to the present invention exhibits high dispersion power and can maintain the dispersed state for a long time.

[0089] <Experimental Example 3> Analysis of Thermal Conductivity of TIM Thermal Pads

[0090] The thermal conductivity of the heat dissipation pads manufactured in the above Example 2 and Comparative Example 4 was evaluated using a TSP 2500S instrument through a biaxial thermal conductivity analysis method, and the evaluation was repeated three times to obtain an average result.

[0091] As a result of the above thermal conductivity evaluation, the average thermal conductivity of the TIM heat dissipation pad containing surface-unmodified alumina of Comparative Example 4 was found to be 5.96 W / mK, whereas the average thermal conductivity of the TIM heat dissipation pad containing surface-modified alumina of Example 2 was found to be 7.96 W / mK, indicating that the thermal conductivity was improved by approximately 74% compared to Comparative Example 4.

[0092] Through the above results, it was confirmed that the heat dissipation pad comprising a thermally conductive filler containing surface-modified alumina according to the present invention exhibits excellent thermal conductivity.

[0094] <Experimental Example 4> Analysis of Thermal Shock and Thermal Stability of TIM Thermal Pads

[0095] <Experimental Example 4-1> Thermal Shock Analysis of TIM Thermal Pads

[0096] The thermal shock of the heat dissipation filler manufactured in Example 1 above was repeated 50 times for 30 minutes in a temperature range of -40 ℃ to 80 ℃ to visually check the external changes of the heat dissipation pad, and the results are shown in Fig. 4.

[0097] As shown in Figure 4, even after the thermal shock test as described above, there was almost no external change in the heat dissipation pad of Example 1, and a result of visual evaluation from an accredited certification body indicated no abnormalities.

[0098] Through the above results, it was confirmed that the heat dissipation pad comprising a thermally conductive filler containing surface-modified alumina according to the present invention exhibits excellent thermal shock durability.

[0100] <Experimental Example 4-2> Analysis of Thermal Stability of TIM Thermal Pads

[0101] The dimensional change of the heat dissipation filler prepared in Example 1 above was measured three times while increasing the temperature from room temperature to 700 ℃ using TGA, and the results are shown in [Table 2] below. The weight change was measured three times, and the results are shown in [Table 3] below.

[0102]

[0103]

[0104] As shown in [Table 2] and [Table 3] above, the heat dissipation filler of Example 1 showed an average dimensional change rate of -0.30% and a weight change rate of -0.03% after heating to 700 ℃, and a weight reduction of 2.545% was observed at 575 ℃, but no change in mass occurred thereafter up to 700 ℃.

[0105] Through the above results, it was confirmed that the heat dissipation pad comprising a thermally conductive filler containing surface-modified alumina according to the present invention exhibits excellent thermal stability.

[0107] Through the results of Experiment Example 4 as described above, it was confirmed that the heat dissipation pad containing a thermally conductive filler containing surface-modified alumina according to the present invention has excellent thermal conductivity while simultaneously exhibiting thermal shock resistance and thermal stability.

Claims

Claim 1 The method comprises the steps of: preparing a solvent by mixing distilled water and ethanol; preparing a mixed solution by adding alumina (Al2O3) to the solvent and stirring it once; ultrasonically cleaning the mixed solution; adding a silane coupling agent to the ultrasonically cleaned mixed solution and stirring it a second time at a temperature of 70 to 90 ℃ for 20 to 40 minutes; adding an aqueous ammonia solution to the mixed solution containing the silane coupling agent and stirring it a third time at a temperature of 70 to 90 ℃ for 8 to 10 hours; cooling the solution stirred a third time while maintaining stirring; and washing and drying the cooled solution to obtain surface-modified alumina; wherein the silane coupling agent is (3-Glycidyloxypropyl)trimethoxysilane (C9H2O3) having a pH of 5 to 7 and containing an epoxy functional group. 20 A method for modifying the surface of an alumina using a silane coupling agent, wherein the alumina is O5Si and is represented by the following [Chemical Formula 1]. [Chemical Formula 1] Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A method for modifying the surface of an alumina using a silane coupling agent, wherein, in claim 1, the second stirring step is stirring at 850 to 950 rpm, the third stirring step is stirring at 850 to 950 rpm, and the cooling step is stirring at 850 to 950 rpm for 2 to 4 hours and cooling to room temperature (15 to 25 ℃). Claim 6 A thermally conductive filler comprising alumina whose surface has been modified by the method according to claim 1, wherein the surface-modified alumina comprises a first size alumina having an average size of 6 to 8 μm and a second size alumina having an average size of 3 to 5 μm in a weight ratio of (6 to 5) :

4. Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 A heat dissipation material comprising surface-modified alumina, comprising: a thermally conductive filler comprising surface-modified alumina according to claim 6; and a two-component addition-curing silicone.

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