Magnesium oxide-based composite and method for producing the same

Abstract

The present invention relates to a magnesium oxide-based composite comprising the element ytterbium (Yb) and magnesium oxide (MgO) crystal grains, and a method for producing the same.

Description

Technical Field

[0001] The present invention relates to a magnesium oxide-based composite and a method for producing the same.

Background Art

[0002] Electronic devices are composed of electronic components such as laminates, printed wiring boards, and multilayer wiring boards. Recent electronic devices are equipped with large-capacity power elements and manufactured with a high-density internal structure, so a higher level of heat dissipation and moisture resistance is required compared to the past. Silica and alumina have been mainly used as fillers for existing semiconductor encapsulation resin compositions. However, due to the physical property of low thermal conductivity of silica, the heat dissipation capacity to cope with the increased heat generation due to high integration, high power, high speed, etc. is not sufficient, so there is a problem in the stable operation of the semiconductor. On the other hand, in the case of alumina, which has a higher thermal conductivity than silica, although the heat dissipation property is improved, there is a problem that the abrasion of the kneader, molding machine, and mold progresses significantly due to the excessive hardness of alumina.

[0003] Therefore, magnesium oxide having a higher thermal conductivity than silica and alumina has been studied as a material for a semiconductor encapsulation resin filler. However, magnesium oxide powder has a problem of higher hygroscopicity than silica powder and cannot maintain stable physical properties. Specifically, when magnesium oxide powder is used as a semiconductor encapsulation resin filler, magnesium oxide reacts with moisture in the air to form magnesium hydroxide on the surface of magnesium oxide, causing the volume of the filler to expand, resulting in problems such as crack generation and reduction of thermal conductivity. Therefore, there is a situation where research is necessary to improve the moisture resistance of magnesium oxide and ensure long-term physical property stability.

Prior Art Documents

Patent Documents

[0004] Republic of Korea Registered Patent Publication No. 10-1878963

Summary of the Invention

[0005] The present invention aims to provide a magnesium oxide-based composite and a method for producing the same, which can improve the low moisture absorption resistance of existing magnesium oxide and ensure long-term physical stability.

[0006] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned should be clearly understood by an ordinary person skilled in the art from the following description. [Means for solving the problem]

[0007] One embodiment of the present invention provides a magnesium oxide-based composite comprising the element ytterbium (Yb) and magnesium oxide (MgO) crystal grains.

[0008] Another embodiment of the present invention provides a method for producing the magnesium oxide composite. Specifically, the present invention provides a method for producing the magnesium oxide composite, comprising the steps of (A) producing a sintering mixture containing magnesium oxide or a magnesium oxide precursor and ytterbium oxide; (B) pre-treating the sintering mixture by at least one of coating, granulation, press molding, and injection molding; and (C) sintering the sintering mixture to crystallize it.

[0009] Another embodiment of the present invention provides an inorganic-organic-inorganic composite comprising particles composed of the magnesium oxide-based composite dispersed within a polymer matrix. [Effects of the Invention]

[0010] A magnesium oxide-based composite according to one embodiment of the present invention has excellent hygroscopicity, thereby solving problems such as the deterioration of physical properties caused by the low hygroscopicity of existing magnesium oxides.

[0011] The effects of the present invention are not limited to those mentioned above, and any other effects not mentioned should be clearly understood by an ordinary person from the following description. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example of evaluation criteria based on sintering temperature for the examples and comparative examples. [Figure 2] This figure shows the weight increase rate after the hygroscopicity test based on the Yb2O3 content and sintering temperature in Examples 1 to 11. [Figure 3] This figure shows SEM images of the composites according to Examples 6 to 11 at a sintering temperature of 1,550°C. [Figure 4] This figure shows the surface EDS analysis results at the crystal grain positions of the composite fabricated according to the examples. [Figure 5] This figure shows the surface EDS analysis results of the region at the grain boundary in a separate phase of the composite fabricated according to the example. [Figure 6] Figure 5 shows the EDS mapping results for the region at the grain boundary in a separate phase. [Figure 7] This figure shows the XRD analysis results before and after the moisture resistance test of the composite according to Example 3 at a sintering temperature of 1,550°C. [Figure 8] This figure shows the XRD analysis results before and after the moisture resistance test of the composite according to Example 6 at a sintering temperature of 1,550°C. [Figure 9] This figure shows an SEM image of the composite surface of Example 6 at different sintering temperatures. [Modes for carrying out the invention]

[0013] The present invention will be described in detail below.

[0014] The present invention can be subjected to various modifications and can have various embodiments, wherein specific embodiments will be illustrated in the drawings and will be described in detail in the detailed description.

[0015] However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention. When explaining the present invention, if it is determined that a specific description of related known technologies makes the gist of the present invention unclear, the detailed description thereof will be omitted.

[0016] The terms used in this specification are only used to explain specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly has a different intention.

[0017] In this specification, when a certain part "includes" a certain component, this means that, unless otherwise stated, it may further include other components rather than excluding other components.

[0018] In this specification, when a certain member is positioned "on" another member, this includes not only the case where a certain member is in contact with another member, but also the case where another member exists between the two members.

[0019] In this specification, ytterbium oxide includes ytterbium(II) oxide (YbO) and ytterbium(III) oxide (Yb2O3), and specifically, it may be ytterbium(III) oxide.

[0020] Hereinafter, the present invention will be described in detail.

[0021] One embodiment of the present invention provides a magnesium oxide-based composite including ytterbium (Yb) element and magnesium oxide (MgO) crystal grains.

[0022] The magnesium oxide composite according to the present invention is characterized by containing the element ytterbium (Yb) in the magnesium oxide base material. Due to the presence of the ytterbium (Yb) element, the magnesium oxide composite according to the present invention can significantly reduce or prevent the formation of magnesium hydroxide on the magnesium oxide surface due to moisture absorption from the air. This gives the magnesium oxide composite according to the present invention the advantage of overcoming the limited uses of existing magnesium oxide due to its low hygroscopicity. Furthermore, the magnesium oxide composite according to the present invention also has the advantage of lowering the sintering temperature during manufacturing and thus reducing manufacturing costs due to the presence of the ytterbium (Yb) element.

[0023] The magnesium oxide composite according to the present invention may be a sintered body with magnesium oxide containing ytterbium (Yb) as the base material, or it may be a ceramic with magnesium oxide as the base material. Furthermore, the magnesium oxide composite according to the present invention may be a solid solution containing ytterbium (Yb) within the magnesium oxide crystal structure. Moreover, the magnesium oxide composite according to the present invention may be a solid solution containing ytterbium (Yb) and other metallic elements within the magnesium oxide crystal structure.

[0024] According to one embodiment of the present invention, the ytterbium (Yb) element may be provided by substituting it for the magnesium (Mg) element in the magnesium oxide (MgO) crystal. More specifically, the ytterbium (Yb) element may be provided for the Mg element in the unit cell of the magnesium oxide crystal grains. 2+ At least a portion of Yb 2+ or Yb 3+ It may also be provided by being replaced by [another term].

[0025] Furthermore, according to one embodiment of the present invention, the ytterbium (Yb) element may be present in the form of ytterbium oxide on the interface and / or surface of the magnesium oxide (MgO) crystal. Specifically, the ytterbium oxide may be present at the grain boundary of the magnesium oxide crystal or in other phases. In this case, the ytterbium oxide may be present irregularly on the surface of the magnesium oxide-based composite.

[0026] According to one embodiment of the present invention, the ytterbium (Yb) element may be provided by substituting it for the magnesium (Mg) element in the magnesium oxide (MgO) crystal, and at the same time, it may be present on the surface of the magnesium oxide (MgO) crystal in the form of ytterbium oxide.

[0027] According to one embodiment of the present invention, the content of ytterbium (Yb) element may be 0.02 at.% or more and 6 at.% or less relative to the magnesium (Mg) element (relative to 100 at.% of the Mg element). Specifically, the content of ytterbium (Yb) element may be 0.02 at.% or more and 5 at.% or less, 0.02 at.% or more and 4 at.% or less, 0.02 at.% or more and 3 at.% or less, 0.02 at.% or more and 2 at.% or less, 0.04 at.% or more and 2 at.% or less, 0.04 at.% or more and 0.4 at.% or less, 0.1 at.% or more and 2 at.% or less, 0.09 at.% or more and 0.5 at.% or less, or 0.1 at.% or more and 0.4 at.% or less, relative to the magnesium (Mg) element. When the content of ytterbium (Yb) element is within the aforementioned range, the moisture resistance of the magnesium oxide composite can be greatly improved, and the sintering temperature during manufacturing can also be lowered. However, if the content of ytterbium (Yb) element is below the aforementioned range, the improvement in the moisture resistance of the magnesium oxide composite may not be sufficient, and if the content of ytterbium (Yb) element exceeds the aforementioned range, the ytterbium (Yb) element or ytterbium oxide may interfere with the growth of magnesium oxide crystal grains.

[0028] The ytterbium (Yb) content may be measured by methods known in the art, such as EDS, WDS, EPMA, XRF, or Rietveld refinement of neutron and X-ray diffraction, and can also be measured by ICP analysis.

[0029] According to one embodiment of the present invention, the magnesium oxide-based composite may further contain at least one additional metal element selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al.

[0030] The aforementioned additional metal element may be derived from at least one additional additive selected from the group consisting of oxides, hydroxides, or carbonites containing at least one selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al.

[0031] Specifically, the additional metal element may be provided by substituting it for the magnesium (Mg) element in the magnesium oxide (MgO) crystal, as with the ytterbium (Yb) element described above, and / or on the surface of the magnesium oxide (MgO) crystal in the form of an additional oxide or compound (e.g., at least one of the following forms: oxide of the additional metal; oxide of ytterbium (Yb) and the additional metal; oxide of magnesium and the additional metal; oxide of magnesium, ytterbium (Yb) and the additional metal; and reaction oxides (compounds) thereof). The additional metal element can be applied to the magnesium oxide composite together with the ytterbium (Yb) element to improve moisture resistance and / or reduce the sintering temperature, thereby reducing manufacturing costs.

[0032] According to one embodiment of the present invention, the content of the additional metal element may be 0.02 at.% or more and 5 at.% or less relative to the magnesium (Mg) element. Specifically, the content of the additional metal element may be 0.02 at.% or more and 5 at.% or less, 0.02 at.% or more and 4 at.% or less, 0.02 at.% or more and 3 at.% or less, 0.02 at.% or more and 2 at.% or less, 0.02 at.% or more and 1 at.% or less, 0.05 at.% or more and 5 at.% or less, 0.05 at.% or more and 4 at.% or less, 0.05 at.% or more and 3 at.% or less, 0.05 at.% or more and 2 at.% or less, 0.05 at.% or more and 1 at.% or less, 0.05 at.% or more and 0.5 at.% or less, or 0.1 at.% or more and 0.5 at.% or less, relative to the magnesium (Mg) element.

[0033] According to one embodiment of the present invention, if the magnesium oxide-based composite further contains the additional metal element, the content of the ytterbium (Yb) element may be 0.02 at.% to 1 at.%, 0.02 at.% to 0.5 at.%, 0.02 at.% to 0.25 at.%, 0.02 at.% to 0.15 at.% or 0.02 at.% to 0.1 at.% relative to the magnesium (Mg) element. If the additional metal element is further included in the magnesium oxide-based composite, the content of the ytterbium (Yb) element may be even lower than when the ytterbium (Yb) element is applied alone. If the magnesium oxide-based composite further contains the additional metal element, and the content range of the ytterbium (Yb) element is within the above range, it is possible to either not hinder the growth of magnesium oxide crystal grains in the magnesium oxide-based composite or promote the growth of magnesium oxide crystal grains, thereby greatly improving moisture resistance.

[0034] According to one embodiment of the present invention, the magnesium oxide composite may have a weight increase rate of less than 1% after a moisture resistance test conducted at 85°C and 85%RH for 72 hours. Specifically, the magnesium oxide composite may have a weight increase rate of less than 0.7% or less than 0.5% after a moisture resistance test conducted at 85°C and 85%RH for 72 hours. In the results of the moisture resistance test of conventional magnesium oxide, the weight increase rate generally exceeds 10%, and even at high sintering temperatures, the weight increase rate remains above 1%. In contrast, the magnesium oxide composite according to the present invention shows significantly improved moisture resistance compared to conventional magnesium oxide.

[0035] According to one embodiment of the present invention, the content of the magnesium oxide crystal grains may be at least 90 wt% of the total composite. Specifically, the content of the magnesium oxide crystal grains may be at least 92 wt% or 95 wt% of the total composite.

[0036] According to one embodiment of the present invention, the magnesium oxide-based composite may be particles or structures of any one shape from amorphous, spherical, elliptical, donut-shaped, and plate-shaped. The magnesium oxide-based composite may also be in powder form, film form, or a predetermined bulk form. Furthermore, the magnesium oxide-based composite may be in the form of fine particles or granular powder in any one shape from amorphous, spherical, elliptical, donut-shaped, and plate-shaped. When the magnesium oxide-based composite according to the present invention is in powder form, it may have a particle size of 1 μm to 200 μm, or 2 μm to 150 μm. In the case of particle size, this may refer to the average particle size of the powder.

[0037] The aforementioned structure of the predetermined shape may be a structure formed by a mold for realizing the predetermined shape.

[0038] Another embodiment of the present invention provides a method for producing the magnesium oxide-based composite described above.

[0039] Specifically, another embodiment of the present invention provides a method for producing a magnesium oxide-based composite, comprising the steps of (A) producing a sintering mixture containing magnesium oxide or a magnesium oxide precursor and ytterbium oxide; (B) pre-treating the sintering mixture by at least one of coating, granulation, press molding, and injection molding; and (C) sintering the sintering mixture to crystallize it.

[0040] According to one embodiment of the present invention, the magnesium oxide precursor may contain at least one of magnesium hydroxide powder, magnesium bicarbonate powder, magnesium carbonate powder, and magnesia (MgO) powder.

[0041] In one embodiment of the present invention, the step of (A1) dispersing the sintering mixture in a solvent may be further included. Specifically, the magnesium oxide precursor, ytterbium oxide, and additional additives selectively described later may be added to the solvent for dispersion and dissolution. For example, if the magnesium oxide precursor is magnesium hydroxide powder, magnesium bicarbonate powder, and / or magnesium carbonate powder, the solvent may be water (distilled water). In another example, if the magnesium oxide precursor is magnesia (MgO) powder, an organic solvent can be used to prevent reaction with water. The organic solvent may be, for example, anhydrous alcohols such as ethanol, methanol, and propanol, but is not limited thereto, and any organic solvent that does not affect the purpose and effect of the present invention can be used without limitation.

[0042] According to one embodiment of the present invention, the sintering mixture may further contain a binder and / or a dispersant. The binder and / or dispersant may further be contained in the solvent, dispersed and dissolved.

[0043] According to one embodiment of the present invention, the binder may be an organic binder, which is suitable because it is burned off during sintering and does not remain in the final magnesium oxide-based composite. The organic binder can be any one used in the art and may include at least one selected from the group consisting of cellulose binder, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, gel binder, and starch.

[0044] According to one embodiment of the present invention, the dispersant may be added for the uniform dispersion of the constituent components introduced into the solvent, and any dispersant used in the art may be used without limitation, for example, ammonium polycarboxylate salts and alkylol ammonium salts may be applied.

[0045] According to one embodiment of the present invention, step (A1) can be performed by using a physical mixing method such as a ball mill to uniformly mix the components in the solvent. When a ball mill is used in step (A1), not only is the component in the solvent mixed uniformly, but there is also the advantage that the powder dispersed in the solvent can be adjusted to a more uniform size.

[0046] According to one embodiment of the present invention, the coating in step (B) can be applied when the final magnesium oxide composite needs to be provided on the surface of a particular electronic component or manufactured in a plate shape. The granulation in step (B) can be applied when the final magnesium oxide composite needs to be manufactured in spherical particles. The press molding in step (B) may be a method in which the sintering mixture is positioned in a predetermined mold and then molded by applying a predetermined pressure, and a variety of methods commonly used in the industry can be applied. Furthermore, the injection molding in step (B) may include any one of the following: a slip casting method in which the sintering mixture is slurryed and injected into a mold; an injection molding method in which the sintering mixture is slurryed and injected into an extruder or the like; and a cast molding method in which the sintering mixture is poured into a mold and molded.

[0047] According to one embodiment of the present invention, step (B) may involve granulating the sintering mixture and then molding it into a predetermined shape. Specifically, step (B) may involve granulating the sintering mixture and then press molding or injection molding it. This allows for adjustment of the particle size of the sintering mixture before the sintering process, and further enables the production of a sintered body in a desired shape.

[0048] According to one embodiment of the present invention, the granulation may be carried out by granulating the sintering mixture using a spray drying method. When using the spray drying method, it is possible to form granules that are more homogeneous and have a controlled particle size, which has the advantage of being able to produce a magnesium oxide composite of spherical fine particles in a simple manner.

[0049] According to one embodiment of the present invention, the ytterbium oxide plays the role of a precursor of the ytterbium (Yb) element in the magnesium oxide-based complex described above. According to one embodiment of the present invention, the ytterbium oxide may be included in an amount of 0.01 mol% to 3 mol% per mol of magnesium oxide in the final magnesium oxide-based complex. Specifically, the ytterbium oxide may be included in an amount of 0.01 mol% to 2.5 mol%, 0.01 mol% to 2 mol%, 0.01 mol% to 1.5 mol%, 0.01 mol% to 1 mol%, 0.02 mol% to 1 mol%, 0.02 mol% to 0.2 mol%, 0.05 mol% to 1 mol%, 0.045 mol% to 0.25 mol%, or 0.05 mol% to 0.2 mol% per mol of magnesium oxide in the final magnesium oxide-based complex. As described above, when adjusting the content of ytterbium oxide, it can be adjusted in the same way as the content of ytterbium (Yb) element in magnesium oxide-based composites.

[0050] According to one embodiment of the present invention, the sintering mixture may further contain at least one additional additive selected from the group consisting of oxides, hydroxides, or carbon oxides, each containing at least one selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al. Specifically, the additional additive may be at least one selected from the group consisting of TiO2, Ti(OH)4, Ti(CO3)2, Nb2O5, ZrO2, Zr(OH)4, Zr(CO3)2, Ga2O3, B2O3, Fe2O3, SnO2, MnO2, Mn2O3, SiO2, V2O5, V2O3, VO2, VO, V(OH)5, V2(CO3)5, Ta2O5, Sb2O5, Y2O3, Eu2O3, Al2O3, Al(OH)3, and Al2(CO3)3. The aforementioned additional additive may be a precursor of the additional metal element in the magnesium oxide-based complex described above.

[0051] According to one embodiment of the present invention, the additional additive may be included in a content of 0.01 mol% or more and 1 mol% or less per mol of magnesium oxide in the final magnesium oxide-based complex. Specifically, the additional additive may be in a content of 0.02 mol% or more and 1 mol% or less, 0.02 mol% or more and 0.5 mol% or less, 0.02 mol% or more and 0.25 mol% or less, 0.02 mol% or more and 0.15 mol% or less, or 0.02 mol% or more and 0.1 mol% or less per mol of magnesium oxide in the final magnesium oxide-based complex. When adjusting the content of the additional additive as described above, it can be adjusted in the same way as the content of the additional metal element in the magnesium oxide-based complex as described above.

[0052] According to one embodiment of the present invention, the total content of the ytterbium oxide and the additional additive may be such that it is 0.01 mol% or more and 10 mol% or less per mole of magnesium oxide in the final magnesium oxide-based complex. Specifically, if the additional additive is further included, the total content of the ytterbium oxide and the additional additive may be 0.01 mol% or more and 5 mol%, 0.01 mol% or more and 3 mol%, 0.01 mol% or more and 2 mol%, 0.02 mol% or more and 1 mol%, or 0.1 mol% or more and 0.5 mol% or less per mole of magnesium oxide in the final magnesium oxide-based complex.

[0053] The reason for using the content of the ytterbium oxide or the additional additive as a reference to the magnesium oxide of the final magnesium oxide-based composite is that, when the magnesium oxide precursor is a magnesium salt such as magnesium hydroxide powder, magnesium bicarbonate powder, or magnesium carbonate powder, it is converted to a magnesium oxide phase by sintering, and therefore the content of the ytterbium oxide is adjusted regardless of the type of magnesium oxide precursor.

[0054] According to one embodiment of the present invention, the sintering temperature in step (C) may be 1,000°C to 1,800°C. Specifically, the sintering temperature can be adjusted according to the content of the ytterbium oxide. The sintering temperature may be 1,250°C to 1,800°C, 1,350°C to 1,800°C, 1,400°C to 1,800°C, 1,400°C to 1,700°C, 1,400°C to 1,600°C, 1,500°C to 1,700°C, or 1,500°C to 1,600°C, depending on the content of the ytterbium oxide. Furthermore, when the additional additive is applied along with the ytterbium oxide in step (C), the sintering temperature can be lower, such as 1000°C to 1500°C, 1200°C to 1600°C, or 1250°C to 1450°C, depending on the degree of diffusion.

[0055] Another embodiment of the present invention provides an inorganic-organic-inorganic composite comprising particles composed of the magnesium oxide-based composite dispersed within a polymer matrix.

[0056] According to one embodiment of the present invention, the polymer matrix may be formed of at least one resin selected from the group consisting of silicone resins, urethane resins, epoxy resins, and thermoplastic resins. The silicone resins, urethane resins, epoxy resins, and thermoplastic resins can be materials commonly used in the industry to form matrices. For example, the thermoplastic resin may include polyolefin resins and polyester resins. The thermoplastic resin may also include at least one of the following: general-purpose plastics such as PE, PP, PMMA, PS, and ABS; engineering plastics such as PBT, PC, PPO, POM, and nylon; super engineering plastics such as PPS, PI, PTFE, and PEEK; and green plastics such as PBAT and PLA.

[0057] According to one embodiment of the present invention, the magnesium oxide composite may be used for at least one of the following purposes: heat transfer material, heat dissipation material, wear-resistant material, insulating material, flame retardant material, and reinforcing material. Specifically, since the magnesium oxide composite has excellent thermal conductivity and moisture resistance, it can be applied to heat dissipation layers and heat dissipation fillers in semiconductor devices, but is not limited thereto. It can be applied to existing applications of alumina and / or silica, and more broadly, it can be applied without limitation to polymer resin-like heat transfer materials, wear-resistant materials, insulating materials, flame retardant materials, and reinforcing materials.

[0058] The present invention will be described in detail below with reference to examples. However, the examples of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the examples described below. The examples herein are provided to give a more complete explanation of the present invention to a person of average skill in the art. [Examples]

[0059] [Examples 1-13] A mixture was prepared by adding Mg(OH)2 powder and Yb2O3 powder as magnesium precursors, PVA (Polyvinyl alcohol) as a binder, and polycarboxylate ammonium salt as a dispersant to distilled water, and stirring to disperse and dissolve the mixture. At this time, the content of Yb2O3 powder was adjusted as shown in Table 1 below. The prepared mixture was then further mixed and pulverized using a ball mill with ZrO2 beads to produce a slurry with a solid content of 20 vol.%. Next, it was granulated using a spray drying method under conditions of 230°C and an atomizer rotation speed of 10,000 rpm. The granulated particles were then sintered at the temperatures shown in Table 1 below to produce a magnesium oxide-based composite. Furthermore, the weight increase rate after a hygroscopicity test of the produced composite under an atmosphere of 85°C and 85% RH for 72 hours is shown in Table 2 below. Furthermore, Table 2 below shows the content (at.%) of Yb element and additional metal elements relative to Mg element in the manufactured composite.

[0060] [Examples 14 and 15] A mixture was prepared by adding MgO powder and Yb2O3 powder as magnesium precursors, PVB (Polyvinyl butyral) as a binder, and alkylolammonium salt as a dispersant to ethyl alcohol, and stirring to disperse and dissolve the mixture. At this time, the content of Yb2O3 powder was adjusted as shown in Table 1 below. The prepared mixture was then further mixed and pulverized using a ball mill with ZrO2 beads to produce a slurry with a solid content of 20 vol.%. Next, it was granulated using a spray drying method under conditions of 90°C and an atomizer rotation speed of 8,000 rpm. The granulated particles were then sintered at the temperatures shown in Table 1 below to produce a magnesium oxide-based composite. Furthermore, the weight increase rate after a hygroscopicity test of the produced composite under an atmosphere of 85°C and 85% RH for 72 hours is shown in Table 2 below. In addition, Table 2 below shows the content of element Yb relative to element Mg (at.%) of the produced composite.

[0061] [Comparative Example 1] A magnesium oxide sintered body was manufactured using the same method as in Example 1, except that Yb2O3 powder was not applied. Furthermore, the weight increase rate of the manufactured sintered body after undergoing a moisture resistance test at 85°C and an 85%RH atmosphere for 72 hours is shown in Table 2 below.

[0062] [Comparative Example 2] A magnesium oxide sintered body was manufactured using the same method as in Example 14, except that Yb2O3 powder was not applied. Furthermore, the weight increase rate of the manufactured sintered body after undergoing a moisture resistance test at 85°C and an 85%RH atmosphere for 72 hours is shown in Table 2 below.

[0063] [Comparative Example 3] A magnesium oxide-based composite was prepared using the same method as in Example 1, except that TiO2 and Nb2O5 were added in the amounts shown in Table 1 below, instead of Yb2O3 powder. Furthermore, the weight increase rate of the prepared composite after undergoing a hygroscopic resistance test at 85°C and 85%RH for 72 hours is shown in Table 2 below. In addition, Table 2 below shows the content (at.%) of the metal element relative to the Mg element in the prepared composite.

[0064] [Table 1]

[0065] [Table 2]

[0066] In Table 1 above, the degree of sintering based on the sintering temperature of the granules was evaluated according to the following criteria.

[0067] -××: A state in which sintering has not occurred at all and no crystal grains have been formed.

[0068] -×: Sintering is minimal, resulting in very low grain growth and a severe lack of density.

[0069] -△: Sintering has occurred to some extent, but the growth of crystal grains is low, resulting in a state of normal or insufficient density.

[0070] -○: A state in which sintering has occurred, crystal grain growth is sufficiently high, and the crystal has high density.

[0071] Figure 1 shows an example of evaluation criteria based on sintering temperature for the examples and comparative examples.

[0072] Figure 2 shows the weight increase rate after the hygroscopicity test with respect to the Yb2O3 content and sintering temperature in Examples 1 to 11. Referring to Figure 2, it can be seen that hygroscopicity tends to increase with increasing sintering temperature, and that the hygroscopicity converges when the Yb2O3 content is at approximately 0.5 mol% relative to MgO.

[0073] Figure 3 shows SEM images of the composites according to Examples 6-11 at a sintering temperature of 1,550°C. Referring to Figure 3, it can be confirmed that ytterbium oxide is present on the surface of the manufactured composite in a separate phase. Specifically, it was confirmed that the amount of ytterbium oxide in a separate phase on the surface of the manufactured composite tends to increase as the Yb2O3 content increases, and that the presence of too much ytterbium oxide hinders the growth of crystal grains and affects the density of the sintered body.

[0074] Figure 4 shows the surface EDS analysis results at the crystal grain locations of the composite fabricated by the example. Based on Figure 4, it is estimated that the crystal grains of the fabricated composite are MgO crystal grains containing trace amounts of element Yb.

[0075] Figure 5 shows the surface EDS analysis results of the region at the grain boundary in a separate phase in the composite fabricated by the example. Figure 6 shows the EDS mapping results of the region at the grain boundary in the separate phase shown in Figure 5. Referring to Figures 5 and 6, it was confirmed that the region formed in the separate phase contained a mixture of ytterbium oxide and magnesium oxide, and it is presumed to be a crystal grain of ytterbium oxide containing trace amounts of Mg.

[0076] Figure 7 shows the XRD analysis results of the composite material according to Example 3 before and after the hygroscopicity test at a sintering temperature of 1,550°C. Referring to Figure 7, it was confirmed that the composite material according to Example 3 at a sintering temperature of 1,550°C, which showed a weight increase rate of 3.28% after the hygroscopicity test, had some magnesium hydroxide formed on its surface.

[0077] Figure 8 shows the XRD analysis results of the composite material according to Example 6 before and after the hygroscopicity test at a sintering temperature of 1,550°C. Referring to Figure 8, it was confirmed that no magnesium hydroxide was detected on the surface of the composite material according to Example 6 at a sintering temperature of 1,550°C, which showed a weight increase rate of 0.47% after the hygroscopicity test.

[0078] Figure 9 shows SEM images of the composite surface of Example 6 at different sintering temperatures. Referring to Figure 9, it can be seen that the crystal grain size tends to increase as the sintering temperature increases, and it was confirmed that the addition of Yb2O3 allows for good growth of MgO crystal grains even at low temperatures below 1,700°C.

Claims

1. A magnesium oxide-based composite containing ytterbium (Yb) element and magnesium oxide (MgO) crystal grains.

2. The magnesium oxide-based composite according to claim 1, wherein the ytterbium (Yb) element is provided by substituting it for the magnesium (Mg) element in the magnesium oxide (MgO) crystal.

3. The magnesium oxide-based composite according to claim 1, wherein the ytterbium (Yb) element is contained on the surface of the magnesium oxide (MgO) crystal in the form of ytterbium oxide.

4. The magnesium oxide-based composite according to claim 1, wherein the content of the ytterbium (Yb) element is 0.02 at.% or more and 6 at.% or less relative to the magnesium (Mg) element.

5. The magnesium oxide-based composite according to claim 1, further comprising at least one additional metal element selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al.

6. The magnesium oxide composite according to claim 1, wherein the weight gain rate after a hygroscopic test conducted at 85°C and in an 85% RH atmosphere for 72 hours is less than 1%.

7. The magnesium oxide-based composite according to claim 1, wherein the content of the magnesium oxide crystal grains is at least 90 wt% of the total composite.

8. The magnesium oxide composite according to claim 1, wherein the magnesium oxide composite is a particle or structure of a predetermined shape, which is one of amorphous, spherical, elliptical, donut-shaped, and plate-shaped.

9. (A) A step of producing a sintering mixture containing magnesium oxide or a magnesium oxide precursor and ytterbium oxide, (B) A step of pre-treating the sintering mixture, comprising at least one of coating, granulation, press molding, and injection molding, (C) A method for producing a magnesium oxide composite, comprising the step of sintering the sintering mixture to crystallize it.

10. A method for producing a magnesium oxide-based composite according to claim 9, wherein the ytterbium oxide is included in a content of 0.01 mol% to 3 mol% or less per 1 mol of magnesium oxide in the final magnesium oxide-based composite.

11. The method for producing a magnesium oxide-based composite according to claim 9, wherein the sintering temperature in step (C) is 1,000°C to 1,800°C.

12. The method for producing a magnesium oxide-based composite according to claim 9, wherein the sintering mixture further comprises at least one additional additive selected from the group consisting of oxides, hydroxides, or carbonoxides containing at least one selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al.

13. The method for producing a magnesium oxide-based complex according to claim 12, wherein the additional additive is included in an amount of 0.01 mol% or more and 1 mol% or less relative to 1 mol of magnesium oxide in the final magnesium oxide-based complex.

14. The method for producing a magnesium oxide-based composite according to claim 12, wherein the total content of the ytterbium oxide and the additional additive is such that the content is 0.01 mol% or more and 10 mol% or less per 1 mol of magnesium oxide in the final magnesium oxide-based composite.

15. (A1) A method for producing a magnesium oxide-based composite according to claim 9, further comprising the step of dispersing the sintering mixture in a water-soluble solvent.

16. The method for producing a magnesium oxide-based composite according to claim 9, wherein the granulation is performed by granulating the sintering mixture using a spray drying method.

17. An inorganic-organic-inorganic composite comprising particles composed of the magnesium oxide-based composite described in claim 1, dispersed within a polymer matrix.

18. The organic-inorganic composite according to claim 17, wherein the polymer matrix is ​​formed of at least one resin selected from the group consisting of silicone resins, urethane resins, epoxy resins, and thermoplastic resins.

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