Method for preparing magnesium oxide particles with improved moisture resistance, and magnesium oxide particles prepared using same

Abstract

A method for preparing magnesium oxide particles with improved moisture resistance by surface modification is disclosed. According to one aspect of the present invention, the method for preparing magnesium oxide particles with improved moisture resistance is provided, the method comprising the steps of: making a gaseous organic silazane-based coating agent come in contact with the surface of magnesium oxide (MgO) particles; and reacting same in a preset environment so that the gaseous coating agent is deposited on the surface of the magnesium oxide particles.

Description

Method for producing magnesium oxide particles with improved moisture resistance and magnesium oxide particles produced thereby

[0001] The present invention relates to a method for producing surface-modified magnesium oxide (MgO) particles to improve moisture resistance and to magnesium oxide particles produced thereby.

[0002] The content described in this section merely provides background information for the present embodiment and does not constitute prior art.

[0003] Thermally conductive materials are typically applied to heat-generating areas of electronic devices to promote heat dissipation and maintain normal operation and performance. However, recent trends in electronic devices, such as lighter weight, smaller size, higher performance, and the inclusion of high-resolution and large-capacity power components, are driving the need for even more advanced heat-dissipating materials.

[0004] Thermally conductive materials that promote heat dissipation in electronic devices and other applications typically consist of a resin composition filled with a thermally conductive filler. Commonly used fillers include silicon dioxide (silica), aluminum oxide (alumina), and aluminum nitride.

[0005] However, silica has relatively low thermal conductivity, making it difficult to cope with increased heat generation due to high integration and high power consumption, which can cause problems in the stable operation of electronic devices. Alumina has superior thermal conductivity compared to silica, which is advantageous for improving heat dissipation characteristics, but its high hardness causes problems such as wear in molding machines / mixers or molds. In addition, aluminum nitride is an expensive raw material, which reduces economic feasibility.

[0006] Meanwhile, magnesium oxide particles exhibit higher thermal conductivity than silica and comparable thermal conductivity to alumina. They also have low hardness and a light specific gravity, making them easy to handle, making them ideal for use in electronic devices. However, magnesium oxide is highly hygroscopic, and its hydration reaction with absorbed moisture can cause cracks and reduced thermal conductivity, leading to expansion of the filler volume.

[0007] Accordingly, various surface treatments are being attempted to improve the moisture resistance / water resistance of magnesium oxide particles, and for example, technologies are being applied to modify the surface of magnesium oxide particles by applying various materials, such as forming a silica-based thin film on the surface of magnesium oxide particles or covering the surface of magnesium oxide particles with epoxy resin.

[0008] However, most conventional surface modification techniques, such as dip coating, disperse particles in a solvent. This makes it difficult to control the thickness of the coating layer and makes it unsuitable for the highly hygroscopic magnesium oxide particles. Furthermore, chemical vapor deposition involves a high-temperature stabilization process, increasing the overall number of steps required to modify the surface of magnesium oxide particles and complicating the conditions.

[0009] One embodiment of the present invention aims to provide a method for manufacturing magnesium oxide particles optimized for use as a heat dissipation material in the electrical and electronic fields by modifying the surface of magnesium oxide particles to improve moisture resistance while maintaining high thermal conductivity.

[0010] In addition, one embodiment of the present invention aims to provide a method for manufacturing magnesium oxide particles using a plasma-based dry coating method. Compared to conventional magnesium oxide coating methods, the manufacturing method of the present invention simplifies the process, ensures excellent moisture resistance even with a relatively short treatment time, and resolves the generation of waste liquid and side products that occur in conventional coating methods.

[0011] According to one aspect of the present invention, a method for producing magnesium oxide particles with improved moisture resistance is provided, comprising the steps of contacting a gaseous organic silazane series coating agent on the surface of magnesium oxide (MgO) particles and reacting the gaseous coating agent in a preset environment so that it is deposited on the surface of the magnesium oxide particles.

[0012] According to one aspect of the present invention, the step of contacting the surface of the magnesium oxide particles with a coating agent includes the step of introducing powdered magnesium oxide particles into a reaction chamber, and the step of supplying a reaction gas formed by bubbling an inert gas and the coating agent into the reaction chamber, while introducing the reaction gas to the magnesium oxide particles in the reaction chamber.

[0013] According to one aspect of the present invention, the coating agent is characterized in that it is formed by at least one of an organic silazane coating agent composed of hexamethyldisilazane, 1,3-diphenyl-1,1,3,3-tetramethyldisilazane, and 1,1,3,3-tetramethyl-1,3-divinyldisilazane.

[0014] According to one aspect of the present invention, the step of reacting the coating agent so that it is deposited on the surface of the magnesium oxide particles is characterized by forming plasma inside the reaction chamber while maintaining the inside of the reaction chamber as a vacuum so that the gaseous coating agent is bound to the surface of the magnesium oxide particles in a powdered state.

[0015] According to one aspect of the present invention, the magnesium oxide particles and the coating agent are characterized in that a reaction is performed within 20 to 50 minutes while the plasma is applied.

[0016] According to one aspect of the present invention, there is provided magnesium oxide particles for use as a heat-dissipating material, which have improved moisture resistance, including magnesium oxide particles and a silicon-based thin film covering the surface of the magnesium oxide particles.

[0017] According to one aspect of the present invention, the silicon-based thin film is characterized in that it is formed by bonding an organic silazane series coating agent to the surface of the magnesium oxide particles.

[0018] According to one aspect of the present invention, the organic silazane series coating agent is characterized by being at least one of the organic silazane coating agents composed of hexamethyldisilazane, 1,3-diphenyl-1,1,3,3-tetramethyldisilazane, and 1,1,3,3-tetramethyl-1,3-divinyldisilazane.

[0019] According to one aspect of the present invention, the magnesium oxide particles including the silicon-based thin film are characterized in that they have a moisture absorption rate of 0.3% or less for 5 days in an atmosphere at room temperature and a relative humidity of 70%.

[0020] According to one aspect of the present invention, the average particle diameter of the magnesium oxide particles is 1 µm to 200 µm.

[0021] According to one aspect of the present invention, the magnesium oxide particles including the silicon-based thin film are characterized in that they are manufactured by the method for manufacturing the magnesium oxide particles.

[0022] As described above, according to one aspect of the present invention, by stably forming a silicon-based thin film layer on the surface of magnesium oxide particles through short-term plasma treatment, there is an advantage in that the moisture resistance of the magnesium oxide particles can be improved while maintaining the shape and thermal conductivity of the particles.

[0023] In addition, according to one aspect of the present invention, since the surface modification of magnesium oxide particles is performed by a plasma-based dry coating method rather than a conventional wet coating method, it is possible to form a thin film coating on the surface of the particles, and the production of by-products such as waste liquid and side reactions can be prevented, so there is an advantage in that magnesium oxide particles can be manufactured in an environmentally friendly manner.

[0024] FIG. 1 is a flowchart illustrating a method for manufacturing magnesium oxide particles according to one embodiment of the present invention.

[0025] Figure 2 shows the results of surface property analysis by contact angle measurement of magnesium oxide particles manufactured by the manufacturing method of one embodiment and comparative example of the present invention.

[0026] FIG. 3 shows the results of Fourier transform infrared spectroscopy (FT-IR) spectrum measurement of the particle surface before and after hydration of magnesium oxide particles manufactured according to the manufacturing method of one embodiment and comparative example of the present invention.

[0027] Figure 4 shows the results of measuring the adhesive strength of an adhesive manufactured including magnesium oxide particles manufactured according to the manufacturing method of one embodiment and a comparative example of the present invention.

[0028] FIG. 5 shows the results of Fourier transform infrared spectroscopy (FT-IR) spectrum measurement after the 8585 test of magnesium oxide particles manufactured according to the manufacturing method of one embodiment and comparative example of the present invention.

[0029] FIG. 6 is a field emission scanning electron microscope (FE-SEM) analysis result measuring the particle state of magnesium oxide particles before and after hydration manufactured according to the manufacturing method of one embodiment and comparative example of the present invention.

[0030] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0031] Terms such as first, second, A, and B may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0032] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0033] The terminology used in this application is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. It should be understood that terms such as "comprise" or "have" in this application do not preclude the presence or possibility of addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification.

[0034] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0035] Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0036] In addition, each configuration, process, procedure or method included in each embodiment of the present invention may be shared within a scope that is not technically inconsistent with each other.

[0037] FIG. 1 is a flowchart illustrating a method for manufacturing magnesium oxide particles according to one embodiment of the present invention.

[0038] Magnesium oxide (MgO) particles according to one embodiment of the present invention are inorganic fillers included in a heat-dissipating material, and are characterized in that a hydrophobic coating layer is formed on the surface to improve moisture resistance.

[0039] Magnesium oxide particles with a hydrophobic coating formed on their surface in this way can maintain the thermal conductivity of the magnesium oxide particles themselves while also ensuring moisture resistance, as the coating is formed with a molecular-level, thin film thickness. As a result, an inorganic filler optimized for use as a heat-dissipating material can be manufactured.

[0040] Surface-modified magnesium oxide particles can be uniformly dispersed in a resin composition, thereby maintaining high fluidity of the resin composition and ensuring excellent heat dissipation performance and adhesive strength.

[0041] Accordingly, magnesium oxide particles according to one embodiment of the present invention can be manufactured into magnesium oxide particles for heat-dissipating materials having excellent moisture resistance through a simple process compared to conventional surface modification methods by going through the manufacturing process described below.

[0042] Prepare powdered magnesium oxide (MgO) particles and a coating agent (S110).

[0043] Powdered magnesium oxide (MgO) particles are the raw material used in the production of surface-modified magnesium oxide particles. These raw magnesium oxide particles are not specifically limited in terms of their manufacturing method or particle shape, and any known, commercially available product can be used. However, considering their thermal conductivity as a heat-dissipating material, the magnesium oxide particles used as the raw material should preferably have a purity of at least 97%.

[0044] In addition, the magnesium oxide particles are in powder form, and fine particles having an average particle diameter ranging from 1 μm to 200 μm can be used. The magnesium oxide particles can be spherical or non-spherical particles. Therefore, in the present invention, "diameter" means not only the diameter in spherical particles, but also the maximum length across the non-spherical particles in non-spherical particles. The size and shape of the magnesium oxide particles in the present invention are not particularly limited, and any shape can be used depending on the use or purpose. However, considering the filling ratio as a heat-radiating filler, the shape of the particles is preferably close to spherical.

[0045] The surface of magnesium oxide particles exhibits high stability despite being chemically active. That is, the surface of magnesium oxide has low reactivity and is unlikely to induce a chemical reaction with the coating agent.

[0046] The present invention modifies the surface properties of magnesium oxide to be hydrophobic by applying a silazane series coating agent to prevent magnesium oxide from undergoing a hydration reaction with moisture.

[0047] As a coating agent for surface modification of powdered magnesium oxide (MgO) particles, an organic silazane series coating agent that can hydrophobically coat the surface of magnesium oxide particles, such as hexamethyldisilazane (HDMS), 1,3-diphenyl-1,1,3,3-tetramethyldisilazane (DPTMDS), and 1,1,3,3-tetramethyl-1,3-divinyldisilazane (DVTMDS), can be used.

[0048] Magnesium oxide (MgO) particles in powder form are introduced into a reaction chamber for plasma-based chemical vapor deposition (PECVD), and the inside of the reaction chamber is created at a preset vacuum level (S120).

[0049] In the present invention, surface modification of magnesium oxide (MgO) particles is performed by a dry coating method, and plasma-based chemical vapor deposition (PECVD) can be applied for this purpose.

[0050] Powder coating is primarily performed using a wet process, typically in a solution. However, wet coating using a solution can produce byproducts, such as wastewater after coating or byproducts generated depending on reaction conditions. Furthermore, wet coating can form a thick coating film on the powder, which can reduce the thermal conductivity of the magnesium oxide particles.

[0051] Furthermore, when chemical vapor deposition is applied to the surface modification of magnesium oxide (MgO), conventional surface modification involves first forming a precursor through a deposition process and then heating the formed precursor to a temperature of 600°C or higher to fix it. This increases the number of modification processes and incurs significant energy consumption for high-temperature heat treatment.

[0052] Accordingly, in the present invention, by applying a dry coating method using plasma-based vapor phase chemical vapor deposition to magnesium oxide (MgO) particles, the formation of by-products such as waste liquid is minimized, and the process required for surface modification is simplified with only a short-time plasma treatment, thereby saving energy, and at the same time, a hydrophobic coating film is formed on the surface of the heating particle with a thickness at the molecular level.

[0053] The device for deposition is not particularly limited, but it is preferable to use a device that can easily react powder particles and gaseous coating agent inside the reaction chamber by maintaining it as a sealed environment.

[0054] The reaction chamber, into which powdered magnesium oxide (MgO) particles are introduced, is vacuumed to facilitate a smooth reaction between the magnesium oxide (MgO) particles and the coating agent. At this time, the preset vacuum level within the reaction chamber can be maintained at the level of 10 mTorr.

[0055] A reaction gas generated by bubbling an inert gas and a coating agent is supplied to a plasma-based chemical vapor deposition (PECVD) reaction chamber, and magnesium oxide (MgO) powder in the reaction chamber is stirred (S130).

[0056] As an inert gas, gases such as argon (Ar), nitrogen (N2), or helium (He) can be used, and the organic silazane series coating agent is generated as a reaction gas by bubbling and supplied to the reaction chamber together with the inert gas. The flow rate of the reaction gas supplied to the reaction chamber is maintained at 3 sccm, and the vacuum level inside the reaction chamber is maintained within the range of 10 mTorr to 70 mTorr, and it is more preferable to maintain a vacuum state of at least 40 mTorr or higher.

[0057] At this time, the magnesium oxide (MgO) particles in powder form introduced into the reaction chamber undergo deposition by stirring with the reaction gas. The stirring of the magnesium oxide (MgO) particles may be implemented using any device capable of stirring the powder within the reaction chamber equipped with a plasma-forming electrode.

[0058] Plasma is formed in a reaction chamber, and a thin film coating layer is formed on the surface of the magnesium oxide (MgO) particles by reacting powdered magnesium oxide (MgO) particles and a gaseous organic silazane series coating agent in a preset environment (S140).

[0059] To coat the surface of magnesium oxide (MgO) particles with a reactive gas component, a voltage is applied through an electrode to ionize the reactive gas and generate plasma. For example, 20 W of power is applied through the electrode to generate plasma, and the reaction is allowed to proceed for at least 10 minutes to form a thin film coating layer on the surface of magnesium oxide (MgO) particles. To form a stable and uniform coating film, the reaction time is preferably within 20 to 50 minutes.

[0060] In this way, a coating film with a molecular thickness can be formed on magnesium oxide (MgO) particles having an average particle diameter ranging from 1 μm to 200 μm using plasma-enhanced chemical vapor deposition (PECVD). Accordingly, magnesium oxide (MgO) particles with hydrophilic surface properties can be made hydrophobic.

[0061] When the reaction is complete, the plasma and gas supply are stopped and the vacuum is released to recover the coated magnesium oxide (MgO) particles (S150).

[0062] In order to improve the moisture resistance of the magnesium oxide (MgO) particles by forming a coating film uniformly applied to the surface of the particles, the steps S120 to S150 described above may be sequentially repeated. However, the above steps need to be repeated within a range in which the thermal conductivity of the magnesium oxide (MgO) particles is not impaired.

[0063] Magnesium oxide (MgO) particles manufactured through the above series of processes can be applied as a heat dissipation material in the electrical and electronic fields, and in particular can be used as a thermally conductive inorganic filler mixed into a resin composition.

[0064] Hereinafter, the moisture resistance improved by surface modification and the adhesive performance when mixed into a resin composition will be examined for magnesium oxide (MgO) particles manufactured by a manufacturing method of one embodiment of the present invention.

[0065] Example

[0066] Hexamethyldisilazane (HMDS) was used as an organosilazane coating agent for surface modification of magnesium oxide (MgO) particles. At this time, argon (Ar) gas was used as an inert gas to supply hexamethyldisilazane (HMDS) to the reaction chamber.

[0067] A series of processes for forming a coating film by reacting powdered magnesium oxide (MgO) particles with hexamethyldisilazane (HMDS) were performed through steps S110 to S150.

[0068] At this time, liquid hexamethyldisilazane (HMDS) was vaporized using argon (Ar) gas at 50°C and supplied to the reaction chamber, and plasma was applied to the reaction chamber at a power of 20 W. In order to evaluate the moisture resistance of magnesium oxide (MgO) particles, surface-modified magnesium oxide (MgO) particles were manufactured by varying the vacuum and reaction time for the magnesium oxide (MgO) particles and gaseous hexamethyldisilazane (HMDS) to react within the reaction chamber. The conditions for each example are shown in Table 1 below.

[0069] Example No. 123 Vacuum (mTorr) 305050 Response time (min) 101020

[0070] Magnesium oxide (MgO) particles of each example were manufactured under the same conditions except for the degree of vacuum and reaction time. The manufactured magnesium oxide (MgO) particles were subjected to contact angle measurements, Fourier transform infrared spectroscopy (FT-IR) on the particle surface, adhesive strength measurements using a die shear test, and measurements using a field emission scanning electron microscope (FE-SEM) to evaluate the coating state and moisture resistance.

[0071] Comparative example

[0072] Powdered magnesium oxide (MgO) particles were coated with hexamethyldisilazane (HMDS) by dry coating of the powder particles.

[0073] After adding powdered magnesium oxide (MgO) particles to the reaction vessel, hexamethyldisilazane (HMDS) was vaporized using nitrogen (N2) gas at room temperature and supplied to the reaction vessel. As in the example, stirring was applied to the reaction vessel to ensure the reaction between the coating agent and the magnesium oxide (MgO) particles.

[0074] Magnesium oxide (MgO) particles and vaporized hexamethyldisilazane (HMDS) were reacted for 10 minutes in a reaction vessel maintained at atmospheric pressure and a temperature of 150°C. Comparative Example 1 is a surface-modified magnesium oxide (MgO) particle produced by performing a reaction once at 150°C for 10 minutes, and the magnesium oxide (MgO) particles of Comparative Example 2 were produced by repeating the reaction twice at 150°C for 10 minutes.

[0075] Figure 2 shows the results of surface characteristic analysis by contact angle measurement of magnesium oxide (MgO) particles manufactured by the manufacturing method of one embodiment and comparative example of the present invention.

[0076] Figure 2a shows the contact angle measurement results for the magnesium oxide (MgO) particles of Examples 1 to 3, and Figure 2b shows the measurement results for the magnesium oxide (MgO) particles of the comparative example.

[0077] Referring to Figures 2a and 2b, Figure (a) shows the contact angle measurement result of raw magnesium oxide (MgO) particles without surface modification, and it can be seen that the surface hydrophilicity is high with a value of 33.6°.

[0078] In addition, it can be confirmed that the magnesium oxide (MgO) particles of Examples 1 and 2 (Fig. 2a, (b) and (c)) manufactured by the manufacturing method of one embodiment of the present invention do not have improved surface hydrophobicity compared to magnesium oxide (MgO) particles that have not undergone surface modification treatment.

[0079] On the other hand, the magnesium oxide (MgO) particles of Example 3 were measured to have a contact angle of 126.5° through surface modification, indicating that the surface modification was completely achieved compared to the raw magnesium oxide (MgO) particles. Therefore, when modifying the surface of the magnesium oxide (MgO) particles, the vacuum of the reaction chamber must be maintained at least 50 mTorr, and the reaction time must be maintained for at least 20 minutes to ensure that the coating agent reacts stably on the surface of the magnesium oxide (MgO) particles.

[0080] Meanwhile, it can be confirmed that the magnesium oxide (MgO) particles manufactured using the manufacturing method of the comparative example of Fig. 2b have a somewhat more hydrophobic surface compared to the raw magnesium oxide particles. However, the difference in reaction time was found to have no significant effect based on the results of the surface hydrophobicity between Comparative Example 1 (Fig. (b)) and Comparative Example 2 (Fig. (c)).

[0081] The contact angle measurement results disclosed in Fig. 2 show that the manufacturing method of the present invention, which deposits by applying plasma in a vacuum state, is advantageous in activating the surface reactivity of magnesium oxide (MgO) particles compared to the method of depositing by increasing the temperature at atmospheric pressure.

[0082] To determine whether the organic silazane-based coating agent is effective in improving the moisture resistance of magnesium oxide (MgO) particles formed with a coating film, magnesium oxide (MgO) particles manufactured using the manufacturing methods of Examples and Comparative Examples were subjected to a hydration reaction, and their surface properties and adhesive properties were evaluated. The results are illustrated in Figures 3 to 6.

[0083] The hydration reaction of magnesium oxide (MgO) particles was performed by placing raw magnesium oxide (MgO) particles and magnesium oxide (MgO) particles of examples and comparative examples subjected to surface modification in a sealed container at room temperature and a relative humidity of 70% for 5 days.

[0084] FIG. 3 shows the results of FT-IR spectrum measurement on the surface of magnesium oxide (MgO) particles manufactured according to the manufacturing method of one embodiment and a comparative example of the present invention before and after hydration.

[0085] Figure 3 (a) shows the measurement results for the magnesium oxide (MgO) particles of Examples 1 to 3 before and after hydration, and Figure 3 (b) shows the measurement results for the magnesium oxide (MgO) particles of Comparative Example 1.

[0086] Referring to Figure 3, it can be seen that the raw magnesium oxide (MgO) particles that have not been modified have a difference in the peak before and after hydration, and in particular, the peak at 1480 cm after hydration -1 and 1420 cm -1 A peak was detected in . This can be interpreted as a peak formed due to the hydration of magnesium oxide (MgO) particles.

[0087] In addition, the magnesium oxide (MgO) particles of Examples 1, 2 and Comparative Example 1 also showed peaks in the same wavelength range as the results of the raw magnesium oxide (MgO) particles after the hydration reaction. However, in the case of Example 2 and Comparative Example 1, where the contact angle results confirmed that the surface was partially hydrophobic, the peak was 1480 cm compared to the raw magnesium oxide (MgO) particles that were not coated. -1 and 1420 cm -1 The peak size was small. This means that although the surface of the magnesium oxide (MgO) particles was partially coated with hexamethyldisilazane (HMDS), the surface was not completely hydrophobic.

[0088] The moisture absorption rate measurement results of the magnesium oxide (MgO) particles of the examples and comparative examples shown in the FT-IR measurement results of Fig. 3 are shown in Table 2 below.

[0089] Bare MgO Example 1 Example 2 Example 3 Comparative Example 1 Moisture absorption rate (%) 0.35 0.34 0.28 0.0 0.17

[0090] As shown in Table 2, the magnesium oxide (MgO) particles of Example 3 were confirmed to absorb little moisture even after a hydration process of 5 days under conditions of 70% relative humidity, as the coating was completely performed. On the other hand, the dry coating method using heat treatment of the comparative example was confirmed to be able to improve the moisture absorption rate of the raw magnesium oxide (MgO) particles by approximately 50%.

[0091] That is, it can be confirmed that the hygroscopicity of magnesium oxide (MgO) particles can be sufficiently improved through surface treatment using an organic silazane series coating agent, and further, that excellent moisture resistance of magnesium oxide (MgO) particles can be secured by applying the plasma-based dry coating method of the present invention.

[0092] Figure 4 shows the results of measuring the adhesive strength of an adhesive including magnesium oxide (MgO) particles manufactured according to the manufacturing method of one embodiment and a comparative example of the present invention.

[0093] A die shear test was performed to verify whether the magnesium oxide (MgO) particles manufactured in Example 3 and Comparative Example 1 were suitable for use as a heat-dissipating material when mixed with a resin composition. A high-temperature curing epoxy adhesive was used as the resin composition. After mixing the magnesium oxide (MgO) particles with the epoxy adhesive at a ratio of 80 wt%, the particles were applied to a 24 mm x 24 mm chip, and a die shear test was performed.

[0094] Figure 4 (a) shows the results of measuring the adhesive strength of magnesium oxide (MgO) particles of Example 3, and Figure 4 (b) shows the results of measuring comparative example 1.

[0095] It can be seen that the adhesive containing magnesium oxide (MgO) particles surface-modified using hexamethyldisilazane (HMDS) has improved die shear strength compared to the adhesive containing raw magnesium oxide (MgO) particles.

[0096] In addition, it was confirmed that the die shear strength of the adhesive using magnesium oxide (MgO) particles reacted by applying plasma was higher than that of the comparative example reacted at atmospheric pressure and 150°C. This confirms that, as proven in the surface characteristic results of the particles above, the surface modification by applying plasma of the present invention is more effective in improving the physical properties of magnesium oxide (MgO) particles.

[0097] FIG. 5 shows the results of Fourier transform infrared spectroscopy (FT-IR) spectrum measurement after the 8585 test of magnesium oxide particles manufactured according to the manufacturing method of one embodiment and comparative example of the present invention.

[0098] In addition to implementing the 5-day hydration process under the aforementioned 70% relative humidity conditions, the 8585 test was performed on magnesium oxide (MgO) particles manufactured by the manufacturing methods of Example 3 and Comparative Example 1.

[0099] The 8585 test analyzed changes in the magnesium oxide (MgO) particles manufactured by each manufacturing method after leaving them for 15 hours under conditions of 85℃ and 85% relative humidity.

[0100] Referring to Fig. 5, it can be seen that the magnesium oxide (MgO) particles manufactured by the manufacturing methods of Example 3 (Plasma) and Comparative Example 1 (Dry) exhibit similar surface functional groups due to the coating prior to the 8585 test. However, after the 8585 test, the magnesium oxide particles of the Example and Comparative Examples exhibited different peaks in the FT-IP measurement results.

[0101] That is, the particles prepared by the plasma coating method of Example 3 showed virtually no change in peaks before and after the 8585 test. On the other hand, the particles prepared by Comparative Example 1, which were dry-coated using heat treatment, showed changes in peaks due to hydration of the magnesium oxide (MgO) particles after the 8585 test. This difference can also be confirmed in the moisture absorption measurement results shown in Table 3.

[0102] Bare MgO Example 3 Comparative Example 1 Moisture absorption rate (%) 0.35 * 0.050.28*Bare MgO is the result of a hydration test at 70% RH, 5 days.

[0103] The moisture absorption rate of the magnesium oxide (MgO) particles that underwent the 8585 test showed a slightly increased result compared to the particles that underwent a 5-day hydration process under 70% relative humidity conditions. However, the magnesium oxide (MgO) particles manufactured using the plasma coating of Example 3 showed an increase in moisture absorption rate of only about 0.05%, confirming that they still possess excellent moisture resistance.

[0104] Figure 6 is a FE-SEM analysis result measuring the particle state of magnesium oxide particles before and after hydration manufactured according to the manufacturing method of one embodiment and comparative example of the present invention.

[0105] Referring to Fig. 6, the magnesium oxide (MgO) particles before hydration are completely maintained in a spherical particle state regardless of the modification method, not only when the raw particles are modified with hexamethyldisilazane (HMDS).

[0106] In the case of raw material particles, the results of measuring the particle surface after the hydration reaction by enlarging it can be seen that the surface state is modified compared to before hydration due to the hydration reaction.

[0107] On the other hand, it was confirmed that the magnesium oxide (MgO) particles modified with hexamethyldisilazane (HMDS) had a reduced degree of surface hydration compared to the raw material particles. In particular, it was found that the magnesium oxide (MgO) particles of the example in which surface modification was performed by applying plasma exhibited superior stability during hydration reaction compared to the particles of the comparative example in which surface modification was performed by dry coating at room temperature.

[0108] In addition, the shape of the magnesium oxide (MgO) particles was found to be maintained regardless of the hydration reaction, making it very suitable for filling properties as an inorganic filler for heat dissipation and for securing fluidity of a resin composition.

[0109] The manufacturing method of the present invention is suitable for forming a sufficiently stable coating film to improve the hygroscopicity of magnesium oxide (MgO) particles. In particular, it was confirmed that organic silazane can be stably deposited on the surface of magnesium oxide (MgO) particles through plasma application for a relatively short period of time.

[0110] Increasing the reaction time between the coating agent and magnesium oxide (MgO) particles during plasma treatment can increase the strength of the coating film. To ensure excellent moisture resistance of the magnesium oxide (MgO) particles, it is recommended to apply 20 W of plasma in a vacuum for at least 20 minutes of reaction time.

[0111] The method for manufacturing magnesium oxide (MgO) particles of the present invention can shorten the precursor fixation time compared to conventional chemical vapor deposition methods, reduce the thermal energy consumption for precursor fixation, and, above all, has the advantage of a simple modification process. Furthermore, compared to conventional wet coating methods, it can form a relatively thin coating film and has the advantage of being an environmentally friendly treatment method because it does not generate waste liquid.

[0112] Furthermore, the magnesium oxide (MgO) particles produced using the manufacturing method of the present invention can secure excellent moisture resistance and filling properties. Furthermore, the processability of molded products can be improved by mixing them with resin compositions, making them ideal for use as next-generation heat-dissipating materials in fields requiring chemical and moisture resistance.

[0113] Although each process is described as being executed sequentially in FIG. 1, this is merely an illustrative description of the technical idea of ​​one embodiment of the present invention. In other words, a person of ordinary skill in the art to which one embodiment of the present invention pertains may modify and apply various modifications and variations, such as changing the order of the processes described in each drawing and executing them or executing one or more of the processes in parallel, without departing from the essential characteristics of one embodiment of the present invention. Therefore, FIG. 1 is not limited to a chronological order.

[0114] The above description is merely an example of the technical idea of ​​the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of ​​the present embodiment, but rather to explain it, and the scope of the technical idea of ​​the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present embodiment.

[0115] This patent is the result of research conducted with the support of the Korea Institute of Industrial Technology Planning and Evaluation with funds from the Korean government (Ministry of Trade, Industry and Energy) in 2023 (Project Unique Number: 1415186247, Subproject Number: 20010106, Project Title: Low Water Permeability and Low Outgassing Adhesive Material).

[0116]

[0117] CROSS-REFERENCE TO RELATED APPLICATION

[0118]

[0119] *This patent application claims priority under 35 USC § 119(a) of Korean Patent Application No. 10-2023-0178460, filed in Korea on December 11, 2023, the entire contents of which are incorporated by reference herein. Furthermore, if this patent application claims priority in countries other than the United States for the same reasons, the entire contents of which are incorporated by reference herein.

Claims

1. A step of contacting a gaseous organic silazane series coating agent with the surface of magnesium oxide (MgO) particles; and A step of reacting in a preset environment so that the coating agent of the gas phase is deposited on the surface of the magnesium oxide particles. A method for producing magnesium oxide particles having improved moisture resistance, comprising:

2. In paragraph 1, The step of contacting the surface of the magnesium oxide particles with a coating agent is as follows: A step of introducing powdered magnesium oxide particles into a reaction chamber; and A method for producing magnesium oxide particles with improved moisture resistance, characterized by comprising a step of supplying a reaction gas formed by bubbling an inert gas and the coating agent into a reaction chamber and introducing the reaction gas into magnesium oxide particles within the reaction chamber.

3. In paragraph 1, A method for producing magnesium oxide particles with improved moisture resistance, characterized in that the coating agent is formed by at least one of an organic silazane coating agent composed of hexamethyldisilazane, 1,3-diphenyl-1,1,3,3-tetramethyldisilazane, and 1,1,3,3-tetramethyl-1,3-divinyldisilazane.

4. In paragraph 2, The step of reacting the coating agent so that it is deposited on the surface of magnesium oxide particles is as follows: A method for producing magnesium oxide particles with improved moisture resistance, characterized in that the inside of the reaction chamber is maintained at a vacuum and plasma is formed inside the reaction chamber so as to bind a gaseous coating agent to the surface of the magnesium oxide particles in a powdered state.

5. In paragraph 4, A method for producing magnesium oxide particles with improved moisture resistance, characterized in that the magnesium oxide particles and the coating agent react within 20 to 50 minutes while the plasma is applied.

6. As magnesium oxide particles for heat-dissipating materials, Comprising magnesium oxide particles and a silicon-based thin film covering the surface of the magnesium oxide particles, Magnesium oxide particles with improved moisture resistance.

7. In paragraph 6, The above silicon-based thin film is, Magnesium oxide particles with improved moisture resistance, formed by bonding an organic silazane series coating agent to the surface of the magnesium oxide particles.

8. In paragraph 7, The above organic silazane series coating agent is, Magnesium oxide particles with improved moisture resistance, characterized by at least one of an organosilazane coating agent composed of hexamethyldisilazane, 1,3-diphenyl-1,1,3,3-tetramethyldisilazane, and 1,1,3,3-tetramethyl-1,3-divinyldisilazane.

9. In paragraph 6, Magnesium oxide particles including the above silicon-based thin film, Magnesium oxide particles with improved moisture resistance, characterized by a moisture absorption rate of 0.3% or less for 5 days in an atmosphere at room temperature and a relative humidity of 70%.

10. In paragraph 6, Magnesium oxide particles with improved moisture resistance, characterized in that the average particle diameter of the magnesium oxide particles is 1 ㎛ to 200 ㎛.

11. In paragraph 7, Magnesium oxide particles including the above silicon-based thin film, Magnesium oxide particles with improved moisture resistance, characterized by being manufactured by the manufacturing method of claim 1.

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