Spherical magnesium oxide, method for producing the same, resin filler, and resin composition

Abstract

The purpose of the present invention is to provide: a spherical magnesium oxide having high sphericity and excellent moisture resistance and properties to be filled in a resin; and a method for producing the spherical magnesium oxide.　The present invention is a spherical magnesium oxide having such properties that the total content of an element belonging to any one of Group-3 to Group-4 on the periodic table (excluding an element belonging to any one of Group-2 and Group-18) and yttrium is 500 to 12,000 ppm, the volume-based cumulative 50% particle diameter (D50) is 1 to 200 μm when measured by a laser diffraction scattering particle size distribution measurement, and the sphericity determined from an SEM image is 1.00 to 1.20.

Description

[Technical Field]

[0001] This invention relates to spherical magnesium oxide with high sphericity and excellent moisture resistance, a method for producing the same, and a resin filler containing the spherical magnesium oxide and a resin composition containing the same. [Background technology]

[0002] Magnesium oxide has excellent electrical insulation, thermal conductivity, and heat resistance, and is used in a variety of industrial applications as a raw material for refractories, insulating material for heaters, abrasive material, vulcanization accelerator for rubber, and pigment for paints and inks. It is also used as a resin filler to impart properties such as heat resistance to resins. Patent Document 1 describes the use of magnesium oxide to impart gas barrier properties to resin films used for packaging food and other products. Patent Document 2 describes the use of magnesium oxide as a white pigment added to resins. Patent Document 3 describes the use of magnesium oxide to improve the light resistance of resins. Patent Document 4 describes the use of magnesium oxide to improve the thermal conductivity of epoxy resins. However, when compounded with resins, magnesium oxide has high hygroscopicity, and problems such as cracking due to volume expansion of the filler when hydrated with moisture in the air occur. Therefore, there is a need for magnesium oxide with excellent moisture resistance that does not cause the above problems even with long-term use. In addition, when using magnesium oxide as a resin filler, high fillability into the resin composition is required to obtain excellent performance.

[0003] When magnesium oxide is used as a resin filler, it is necessary to have good filling properties and moisture resistance. Patent Document 5 proposes spherical magnesium oxide with a smooth surface and dense texture obtained by adding a lithium compound. Patent Document 6 proposes spherical magnesium oxide with a smooth surface and excellent moisture resistance and filling properties obtained by adjusting the boron and iron content within a certain range. Patent Document 7 proposes spherical magnesium oxide with excellent moisture resistance and fluidity of the resin composition when filled into a resin, obtained by adjusting the boron and lithium content within a certain range. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-131494 [Patent Document 2] Japanese Patent Publication No. 2015-101614 [Patent Document 3] Japanese Patent Publication No. 2009-227725 [Patent Document 4] Japanese Patent Publication No. 2017-186578 [Patent Document 5] Japanese Patent Publication No. 2016-088838 [Patent Document 6] Japanese Patent Publication No. 2018-131378 [Patent Document 7] International Publication No. 2020 / 203710 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, while the spherical magnesium oxide obtained by the above-described method exhibits improved moisture resistance and resin-fillability, it requires control of the boron and lithium content. Furthermore, the high content of boron or lithium reduces the properties of magnesium oxide (insulation, heat resistance, and thermal conductivity), and these elements are more likely to leach into the resin, negatively impacting the performance of final products such as electronic devices. Moreover, the presence of lithium in magnesium oxide negatively affects the fluidity of the resin composition when filled into the resin, so a low lithium content is desirable. Therefore, the object of the present invention is to provide spherical magnesium oxide and a method for producing the same, which have high sphericity, excellent moisture resistance and resin-fillability, without containing a certain amount of boron or lithium. [Means for solving the problem]

[0006] To solve the above problems, the inventors conducted various studies and found that by adjusting the content of elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18), spherical magnesium oxide with high sphericity, excellent moisture resistance, and superior filling properties for resins can be obtained even without containing a certain amount of boron or lithium. Furthermore, they found that adjusting the content of yttrium in addition to elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18) is also effective in obtaining spherical magnesium oxide with high sphericity, excellent moisture resistance, and superior filling properties for resins.

[0007] In other words, the present invention relates to a material in which the total content of elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18) and yttrium is 500 to 12,000 ppm, and the cumulative 50% particle size (D) on a volume basis is determined by laser diffraction scattering particle size distribution measurement. 50 The material is located in spherical magnesium oxide, with a diameter in the range of 1 to 200 μm and a sphericity readable from the SEM image of 1.00 to 1.20.

[0008] In addition, the present invention relates to spherical magnesium oxide in which the total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) is 500 to 12,000 ppm, and the volume-based cumulative 50% particle diameter (D 50 ) is in the range of 1 to 200 μm, and the sphericity read from the SEM photograph is 1.00 to 1.20.

[0009] In addition, the present invention relates to a resin filler containing the above spherical magnesium oxide.

[0010] In addition, the present invention relates to a resin composition containing the above resin filler.

[0011] In addition, the present invention 1) A step of reacting an aqueous magnesium salt solution with an aqueous carbonate solution, and then aggregating the produced magnesium carbonate to obtain a spherical magnesium carbonate slurry; 2) A step of filtering, washing with water and drying the spherical magnesium carbonate slurry to obtain spherical magnesium carbonate particles; 3) A step of firing the spherical magnesium carbonate particles to obtain spherical magnesium oxide; The method for producing spherical magnesium oxide includes the above steps 1) to 3), and in at least one of the above steps 1) to 3), the total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) and yttrium in the spherical magnesium oxide after firing is 500 to 12,000 ppm, and the amounts of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) and yttrium are adjusted.

[0012] In addition, the present invention 1) A step of reacting an aqueous magnesium salt solution with an aqueous carbonate solution, and then aggregating the produced magnesium carbonate to obtain a spherical magnesium carbonate slurry; 2) A step of filtering, washing with water and drying the spherical magnesium carbonate slurry to obtain spherical magnesium carbonate particles; 3) firing the spherical magnesium carbonate particles to obtain spherical magnesium oxide; and in at least one of the steps (1) to (3), the total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) in the fired spherical magnesium oxide is 500 to 12,000 ppm, and the amount of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) is adjusted, characterized in that the method for producing spherical magnesium oxide is provided.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide spherical magnesium oxide having a high sphericity, excellent moisture resistance and filling property into resins, and a method for producing the same.

Brief Description of the Drawings

[0014] [Figure 1] An SEM photograph of the spherical magnesium oxide of Example 1 is shown.

Embodiments for Carrying Out the Invention

[0015] The spherical magnesium oxide of the present invention has a total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) and yttrium of 500 to 12,000 ppm, and the cumulative 50% particle diameter (D 50 ) based on volume by laser diffraction scattering particle size distribution measurement is in the range of 1 to 200 μm, and the sphericity read from the SEM photograph is 1.00 to 1.20.

[0016] Further, the spherical magnesium oxide of the present invention has a total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) of 500 to 12,000 ppm, and the cumulative 50% particle diameter (D 50The diameter is in the range of 1 to 200 μm, and the sphericity read from the SEM image is 1.00 to 1.20. In this specification, ppm refers to mass ppm unless otherwise specified.

[0017] In this invention, by controlling the total content of elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18) and yttrium to 500 to 12,000 ppm, the cumulative 50% particle size (D) based on volume measured by laser diffraction scattering particle size distribution measurement is achieved. 50 The spherical magnesium oxide obtained has a diameter in the range of 1 to 200 μm and a high sphericity of 1.00 to 1.20 as read from SEM images, and exhibits excellent moisture resistance. Due to this high sphericity, the spherical magnesium oxide of the present invention exhibits excellent fillability in resins.

[0018] Furthermore, in this invention, for example, by controlling the total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to groups 2 and 18) to 500 to 12,000 ppm, the cumulative 50% particle size (D) based on volume measured by laser diffraction scattering particle size distribution measurement can be controlled. 50 The spherical magnesium oxide obtained has a diameter in the range of 1 to 200 μm and a high sphericity of 1.00 to 1.20 as read from SEM images, and exhibits excellent moisture resistance. Due to this high sphericity, the spherical magnesium oxide of the present invention exhibits excellent fillability in resins.

[0019] In the present invention, the elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) specifically refer to sodium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, and bromine. For example, it is preferable that at least one element is selected from the group consisting of sodium, aluminum, silicon, phosphorus, chlorine, potassium, and titanium, and more preferably that at least one element is selected from the group consisting of aluminum, silicon, phosphorus, and titanium. It is also preferable that at least one element is selected from the group consisting of aluminum, silicon, and titanium. In the present invention, by adjusting the content of elements belonging to the third and fourth periods of the periodic table, spherical magnesium oxide with excellent moisture resistance, high sphericity, and a smooth surface can be obtained.

[0020] In the present invention, for example, the total content of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) is 500 to 12,000 ppm, preferably 500 to 10,000 ppm, and more preferably 500 to 8,000 ppm. If the total content is less than 500 ppm, spherical magnesium oxide with excellent moisture resistance, high sphericity, and a smooth surface cannot be obtained. If the total content is greater than 12,000 ppm, excessive particle growth and adhesion between particles are likely to occur, making it impossible to obtain spherical magnesium oxide with high sphericity.

[0021] The spherical magnesium oxide of the present invention is obtained by adjusting the total content of sodium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, bromine, and yttrium to a predetermined amount (for example, 500 to 12,000 ppm, preferably 500 to 10,000 ppm, more preferably 500 to 8,000 ppm). This makes it possible to obtain spherical magnesium oxide with excellent moisture resistance, high sphericity, and a smooth surface. It is also preferable to adjust the total content of aluminum, silicon, phosphorus, manganese, titanium, and yttrium to the above predetermined amount in the spherical magnesium oxide of the present invention. For example, the total content of aluminum, silicon, phosphorus, manganese, and titanium in the spherical magnesium oxide of the present invention may be adjusted to the above predetermined amount, or the total content of aluminum, silicon, and titanium may be adjusted to the above predetermined amount.

[0022] The spherical magnesium oxide of the present invention can contain, for example, a predetermined amount (for example, 500 to 12,000 ppm, preferably 500 to 10,000 ppm, more preferably 500 to 8,000 ppm) of at least one element selected from the group consisting of sodium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, bromine, and yttrium, thereby obtaining spherical magnesium oxide with excellent moisture resistance, high sphericity, and a smooth surface. Furthermore, it is also preferable that the spherical magnesium oxide of the present invention contains the above predetermined amount of at least one element selected from the group consisting of aluminum, silicon, phosphorus, manganese, titanium, and yttrium. Furthermore, for example, the spherical magnesium oxide of the present invention may contain, for example, at least one selected from the group consisting of aluminum, silicon, phosphorus, manganese, and titanium in the above-mentioned predetermined amount, or it may contain at least one selected from the group consisting of aluminum, silicon, and titanium in the above-mentioned predetermined amount.

[0023] In this invention, spherical magnesium oxide with excellent moisture resistance, high sphericity, and a smooth surface can be obtained even without containing a certain amount of boron, thus allowing for an extremely low boron content. Therefore, in this invention, the boron content can be, for example, less than 10 ppm, preferably less than 9 ppm, and more preferably less than 8 ppm. By reducing the boron content, a deterioration in the properties of magnesium oxide can be prevented. Furthermore, since the elution of boron into the resin can be reduced, errors in electronic circuits can be prevented when used in applications such as electronic devices.

[0024] In this invention, spherical magnesium oxide with excellent moisture resistance, high sphericity, and a smooth surface can be obtained even without containing a certain amount of lithium, thus allowing for an extremely low lithium content. Therefore, in this invention, the lithium content can be, for example, less than 15 ppm, preferably less than 10 ppm, and more preferably less than 5 ppm. By reducing the lithium content, a decrease in the insulating properties of magnesium oxide can be prevented. Furthermore, since the elution of lithium into the resin can be reduced, a decrease in the performance of the final product can be prevented.

[0025] In the present invention, the calcium content is preferably less than 700 ppm, more preferably less than 600 ppm, and more preferably less than 500 ppm. When the calcium content is 700 ppm or more, moisture resistance tends to decrease, and it is difficult to obtain spherical magnesium oxide with high sphericity.

[0026] In this invention, the cumulative 50% particle size (D) based on volume is measured by laser diffraction scattering particle size distribution measurement. 50 The particle size is in the range of 1 to 200 μm, preferably 5 to 100 μm, and more preferably 10 to 50 μm. For example, 10 to 150 μm is also a preferred range.

[0027] In the present invention, the sphericity read from SEM photographs that affect the filling property into the resin is 1.00 to 1.20, preferably 1.00 to 1.15, and more preferably 1.00 to 1.10. In the present invention, for 100 particles in an electron microscope photograph taken using a scanning electron microscope (SEM), the lengths of the major axis and the minor axis passing through the center of the particle are measured, the ratio of the major axis / minor axis is obtained, and the average value thereof is defined as the sphericity.

[0028] In the present invention, the BET specific surface area is, for example, 0.01 to 1.00 m 2 / g, preferably 0.05 to 0.80 m 2 / g, and more preferably 0.10 to 0.60 m 2 / g.

[0029] There is no particular limitation on the method for producing the spherical magnesium oxide of the present invention, but for example, it can be produced as follows.

[0030] 1) After reacting an aqueous magnesium salt solution and an aqueous carbonate solution, the produced magnesium carbonate is aggregated to obtain a spherical magnesium carbonate slurry. 2) The spherical magnesium carbonate slurry is filtered, washed with water, and dried to obtain spherical magnesium carbonate particles. 3) The target spherical magnesium oxide is obtained by firing the spherical magnesium carbonate particles in the air. At this time, until the final firing, so that the total content of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) and yttrium in the spherical magnesium oxide after the final firing is 500 to 12,000 ppm, the amount of elements belonging to the 3rd to 4th periods of the periodic table (excluding elements belonging to Group 2 and Group 18) is adjusted by addition, mixing, etc.

[0031] The total content of elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18) and yttrium is adjusted by, specifically, a) adding compounds containing the above elements to an aqueous magnesium salt solution and / or an aqueous carbonate solution, b) adding compounds containing the above elements to the resulting spherical magnesium carbonate slurry, or c) mixing compounds containing the above elements with the resulting spherical magnesium carbonate particles, thereby adjusting the content in the final spherical magnesium oxide.

[0032] Furthermore, it can be manufactured, for example, as follows:

[0033] 1) After reacting a magnesium salt aqueous solution with a carbonate aqueous solution, the resulting magnesium carbonate is agglomerated to obtain a spherical magnesium carbonate slurry. 2) The spherical magnesium carbonate slurry is filtered, washed with water, and dried to obtain spherical magnesium carbonate particles. 3) The spherical magnesium carbonate particles are calcined in the atmosphere to obtain the desired spherical magnesium oxide. At this time, before the final calcination, the amount of elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18) in the spherical magnesium oxide after the final calcination is adjusted by adding, mixing, etc., so that the total content of these elements in the spherical magnesium oxide after the final calcination is between 500 and 12,000 ppm.

[0034] The total content of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) is adjusted by, specifically, a) adding a compound containing the above elements to an aqueous magnesium salt solution and / or an aqueous carbonate solution, b) adding a compound containing the above elements to the resulting spherical magnesium carbonate slurry, or c) mixing a compound containing the above elements with the resulting spherical magnesium carbonate particles, thereby adjusting the content in the final spherical magnesium oxide.

[0035] The compounds used for the above additions and mixtures are not particularly limited and can be used as long as they contain elements belonging to the 3rd and 4th periods of the periodic table (excluding elements belonging to groups 2 and 18). Similarly, yttrium can be used as long as it contains yttrium.

[0036] The aluminum source is not particularly limited as long as it is an aluminum-containing compound, but for example, aluminum hydroxide, aluminum oxide, aluminum carbonate, aluminum chloride, aluminum nitrate, aluminum acetate, aluminum sulfate, etc. can be used.

[0037] The silicon source is not particularly limited as long as it is a silicon-containing compound, but for example, silicon oxide and silicates can be used. Examples of silicon oxide include crystalline silica, amorphous fumed silica, and colloidal silica. Examples of silicates include sodium silicate, magnesium silicate, potassium silicate, and calcium silicate.

[0038] The phosphorus source is not particularly limited as long as it is a phosphorus-containing compound, but for example, phosphoric acid and phosphates can be used. Examples of phosphates include magnesium phosphate, sodium phosphate, potassium phosphate, and ammonium phosphate.

[0039] The chlorine source is not particularly limited as long as it is a compound containing chlorine, but examples include sodium chloride, magnesium chloride, potassium chloride, and calcium chloride.

[0040] The bromine source is not particularly limited as long as it is a compound containing bromine, but examples include sodium bromide, magnesium bromide, potassium bromide, calcium bromide, etc.

[0041] The sodium source is not particularly limited as long as it is a compound containing sodium, but examples include sodium chloride, sodium carbonate, sodium phosphate, sodium hydroxide, and sodium nitrate.

[0042] Potassium sources are not particularly limited as long as they are potassium-containing compounds, but examples include potassium chloride, potassium carbonate, potassium phosphate, potassium hydroxide, and potassium nitrate.

[0043] The titanium source is not particularly limited as long as it is a titanium-containing compound, but examples include titanium dioxide (anatase type, rutile type), titanium chloride, titanium hydroxide, titanium bromide, titanium fluoride, and magnesium titanate.

[0044] The manganese source is not particularly limited as long as it is a manganese-containing compound, but examples include manganese dioxide, manganese hydroxide, manganese carbonate, manganese chloride, and manganese nitrate.

[0045] The yttrium source is not particularly limited as long as it is a compound containing yttrium, but examples include yttrium oxide, yttrium chloride, and yttrium nitrate.

[0046] Furthermore, it is preferable to control the boron content of the spherical magnesium oxide after final calcination to less than 10 ppm, the lithium content to less than 15 ppm, and the calcium content to less than 700 ppm. The methods for reducing the boron, lithium, and calcium content are not particularly limited, but known processes can be used, or a combination thereof, such as repulping wash which involves repeatedly reslurring the precursor magnesium carbonate cake and washing it with water after filtration, pretreatment with an adsorbent of an aqueous magnesium salt solution, and adjustment of the temperature rise profile during calcination. In addition, the content of each of the above elements can be controlled to a low level by selecting raw materials that do not contain these elements and appropriately managing the possibility of their inclusion in the manufacturing process.

[0047] The magnesium salt used in the above-mentioned aqueous magnesium salt solution is not particularly limited, but for example, magnesium chloride, magnesium nitrate, magnesium sulfate, and magnesium acetate, as well as combinations thereof, can be selected and used.

[0048] The carbonate used in the above-mentioned aqueous carbonate solution is not particularly limited, but can be selected from, for example, sodium carbonate, potassium carbonate, ammonium carbonate, or combinations thereof.

[0049] The magnesium salt concentration in the magnesium salt aqueous solution is preferably 1 to 30% by mass, and the carbonate concentration in the carbonate aqueous solution is preferably 1 to 30% by mass. The reaction between the magnesium salt aqueous solution and the carbonate aqueous solution is, for example, the reaction of [Mg in solution] 2+ ]:[CO3 2- This can be carried out under conditions where the ion concentration ratio of ] is 1.2:1 to 1:1.5.

[0050] In the present invention's method for producing spherical magnesium oxide, first, a magnesium salt aqueous solution is reacted with a carbonate aqueous solution, and then the resulting magnesium carbonate is agglomerated to obtain a spherical magnesium carbonate slurry. Here, the magnesium carbonate produced by reacting the magnesium salt aqueous solution with the carbonate aqueous solution is heated to a temperature of, for example, 60-100°C and held for 0.1-5 hours to obtain a volume-based cumulative 50% particle size (D) measured by laser diffraction scattering particle size distribution measurement. 50 ) can be appropriately aggregated into spherical shapes with a diameter of 1 to 200 μm and a sphericity of 1.00 to 1.30.

[0051] The spherically aggregated magnesium carbonate slurry is filtered, washed with water, and dried, for example, by a method common in the art, to obtain spherical magnesium carbonate particles.

[0052] The magnesium carbonate particles obtained in the above manufacturing method may be anhydrous magnesium carbonate, normal magnesium carbonate, or basic magnesium carbonate, but basic magnesium carbonate is preferred.

[0053] The firing conditions for spherical magnesium carbonate particles are not particularly limited as long as the magnesium carbonate is thermally decomposed into magnesium oxide. For example, the temperature is preferably 1000°C to 1800°C, more preferably 1100°C to 1700°C, and particularly preferably 1200°C to 1600°C. The firing time depends on the firing temperature, but is preferably 0.5 to 10 hours. If the firing temperature is less than 1000°C, the particles will not sinter sufficiently, and if it exceeds 1800°C, the particles will sinter together and form coarse aggregates, so the temperature should be adjusted to the above range.

[0054] The spherical magnesium oxide of the present invention is characterized by having sufficient moisture resistance even without surface treatment, but surface treatment can be applied using known methods to further improve moisture resistance. The surface treatment agent used to surface treat the spherical magnesium oxide of the present invention is not particularly limited, but for example, colloidal silica, silane coupling agents, titania sol, titanate coupling agents, phosphorus compounds, alumina sol, aluminate coupling agents, zirconium coupling agents, etc. can be used.

[0055] Examples of silane coupling agents include vinyltrichlorosilane, vinyltrialkoxysilane, glycidoxypropyltrialkoxysilane, and methacryloxypropylmethyldialkoxysilane.

[0056] Examples of titanate-based coupling agents include tetraisopropyl titanate, tetran-butyl titanate, tetraoctyl titanate, tetrastearyl titanate, isopropyl triisostearoyl titanate, tetraoctylbis(ditridecylphosphite) titanate, and bis(dioctyl pyrophosphate) oxyacetate titanate.

[0057] The phosphorus compound is not particularly limited as long as it can react with magnesium oxide to form a magnesium phosphate compound, but examples include phosphoric acid, phosphate salts, and acidic phosphate esters. These may be used alone or in combination of two or more. Examples of acidic phosphate esters include isopropyl acid phosphate, 2-ethylhexyl acid phosphate, oleyl acid phosphate, methyl acid phosphate, ethyl acid phosphate, propyl acid phosphate, butyl acid phosphate, lauryl acid phosphate, and stearyl acid phosphate.

[0058] Examples of aluminate coupling agents include aluminum isopropylate, monosec-butoxyaluminum diisopropylate, aluminum sec-butyrate, aluminum ethyl acetacetate diisopropylate, aluminum tris(ethyl acetacetate), and aluminum alkyl acetacetate diisopropylate.

[0059] Examples of zirconium-based coupling agents include n-propyl zirconate and n-butyl zirconate.

[0060] The spherical magnesium oxide of the present invention has high sphericity, excellent moisture resistance, and excellent resin-filling properties, making it suitable for incorporation into resins as a filler and useful as a resin filler. For example, it can be suitably used as a thermally conductive filler, heat-resistant filler, gas barrier filler, light-resistant filler, etc., and is particularly excellent as a thermally conductive filler.

[0061] Examples of resins usable in the present invention include thermosetting resins and thermoplastic resins. Thermosetting resins are not particularly limited, but examples include phenolic resins, urea resins, melamine resins, alkyd resins, polyester resins, epoxy resins, diallyl phthalate resins, polyurethane resins, and silicone resins. Thermoplastic resins are not particularly limited, but examples include polyamide resins, polyacetal resins, polycarbonate resins, polybutylene terephthalate resins, polyolefin resins, polysulfone resins, polyamide-imide resins, polyetherimide resins, polyarylate resins, polyphenylene sulfide resins, polyetheretherketone resins, fluororesins, and liquid crystal polymers.

[0062] The amount of spherical magnesium oxide blended in the resin composition of the present invention can be appropriately determined according to the properties required for the resin composition and is not particularly limited. However, as an example, spherical magnesium oxide can be used in the range of 0.1 to 100 parts by mass per 100 parts by mass of resin.

[0063] The resin composition containing spherical magnesium oxide of the present invention can be used in various fields depending on the properties of the resin. [Examples]

[0064] The present invention will be described in detail by the following embodiments, but these embodiments do not limit the present invention in any way.

[0065] <Measurement Methods and Evaluation Methods> (1) Method for measuring elemental content Elemental content was measured by ICP emission spectroscopy. After completely dissolving the sample in acid, the content of each element was measured using an ICP analyzer (PS3520 VDD, Hitachi High-Tech Science Corporation). In Tables 1 and 2 below, if the content of each element was below the detection limit, it was indicated as a trace amount, <1 ppm.

[0066] (2) Method for measuring BET specific surface area The specific surface area (BET) was measured using a specific surface area measuring device (Macsorb, manufactured by Mounttech Co. Ltd.) and the gas adsorption method (BET method) with nitrogen gas.

[0067] (3) Cumulative 50% particle size (D) based on volume 50 ) Measurement sample 0.1 × 10 -3 The material was precisely weighed in kg, dispersed in 40 mL of methanol, and measured using a laser diffraction scattering particle size analyzer (MT3300, manufactured by Nikkiso Co., Ltd.).

[0068] (4) Sphericity and surface smoothness that can be read from SEM images A scanning electron microscope (SEM) (JSM6510LA, manufactured by JEOL Ltd.) was used. For 100 particles in the electron microscope images, the lengths of the major axis and minor axis passing through the center of each particle were measured, the ratio of major axis to minor axis was calculated, and the average value was defined as the sphericity. In addition, the surface condition of spherical magnesium oxide in the electron microscope images taken with the scanning electron microscope (SEM) was evaluated as follows: ○ indicates that there are almost no fine particles on the surface of the spherical magnesium oxide and the surface is smooth; △ indicates that there are multiple fine particles on the surface but the surface is smooth, or that there are almost no fine particles on the surface but the surface is uneven and not smooth; and × indicates that there are multiple fine particles on the surface of the spherical magnesium oxide and the surface is uneven and not smooth.

[0069] (5) Humidity resistance evaluation by constant temperature and humidity test The moisture resistance of spherical magnesium oxide was evaluated by the mass increase rate obtained through constant temperature and humidity testing. A constant temperature and humidity chamber, THN040FA manufactured by Advantec Toyo Co., Ltd., was used. The mass increase rate was determined after 10 g of spherical magnesium oxide was exposed to an environment of 85°C and 85% RH for 168 hours using the constant temperature and humidity chamber.

[0070] <Example 1> A magnesium nitrate hexahydrate (special grade, manufactured by Kanto Chemical Co., Ltd.) was dissolved in deionized water to prepare an aqueous solution of approximately 20% by mass of magnesium nitrate. A potassium carbonate aqueous solution (special grade, manufactured by Kanto Chemical Co., Ltd.) was dissolved in deionized water to prepare an aqueous solution of approximately 15% by mass of potassium carbonate. [Mg 2+ ]:[CO3 2- Magnesium carbonate was synthesized by reacting an aqueous solution of magnesium nitrate and an aqueous solution of potassium carbonate so that the ion concentration ratio of the two was 1:1. After the reaction, the magnesium carbonate slurry was heated to 90°C and held for 1 hour to prepare a slurry of spherical magnesium carbonate. Silicon dioxide (special grade, manufactured by Kanto Chemical Co., Ltd.) was added to this slurry so that the silicon content in the final spherical magnesium oxide was 2,500 ppm. Then, the slurry was filtered, washed with water, and dried to obtain spherical magnesium carbonate particles. The obtained spherical magnesium carbonate particles were calcined in an electric furnace at 1500°C for 1 hour to obtain spherical magnesium oxide particles. Note that the particle size (D) of the spherical magnesium carbonate particles before calcination was measured. 50 The diameter was 20.5 μm, and the sphericity was 1.12.

[0071] <Example 2> Spherical magnesium oxide was obtained by the same method as in Example 1, except that silicon dioxide (special grade, manufactured by Kanto Chemical Co., Ltd.) was added so that the silicon content in the final spherical magnesium oxide was 5,000 ppm. Note that the particle size (D) of the spherical magnesium carbonate particles before calcination was 50 The diameter was 20.3 μm, and the sphericity was 1.12.

[0072] <Example 3> Spherical magnesium oxide was obtained by the same method as in Example 1, except that aluminum oxide (Kanto Chemical Co., Ltd., special grade) was added so that the aluminum content in the final spherical magnesium oxide was 2,500 ppm, instead of adding silicon dioxide. The particle size (D) of the spherical magnesium carbonate particles before calcination was also measured. 50 The diameter was 20.2 μm, and the sphericity was 1.13.

[0073] <Example 4> Spherical magnesium oxide was obtained by the same method as in Example 1, except that titanium dioxide (anatase type, Grade 1, manufactured by Kanto Chemical Co., Ltd.) was added instead of silicon dioxide so that the titanium content in the final spherical magnesium oxide was 7,500 ppm. The particle size (D) of the spherical magnesium carbonate particles before calcination was also measured. 50 The diameter was 20.5 μm, and the sphericity was 1.13.

[0074] <Comparative Example 1> Spherical magnesium oxide was obtained by the same method as in Example 1, except that silicon dioxide was not added. The particle size (D) of the spherical magnesium carbonate particles before calcination was measured. 50 The diameter was 19.8 μm, and the sphericity was 1.12.

[0075] <Result> The spherical magnesium oxide samples from Examples 1-4 and Comparative Example 1 were subjected to the above measurements and evaluations. The results are shown in Table 1 below. The content of each element belonging to the third and fourth periods of the periodic table, other than those shown in Table 1, was 10 ppm or less. Furthermore, the content of yttrium was 10 ppm or less.

[0076] [Table 1]

[0077] As is clear from Table 1, the spherical magnesium oxide of Examples 1-4 had high sphericity and excellent moisture resistance. On the other hand, the spherical magnesium oxide of the comparative example was inferior in both sphericity and moisture resistance.

[0078] Furthermore, spherical magnesium oxide was obtained in Examples 5-9 as described below, and measurements and evaluations were performed in the same manner as in Examples 1-4 and Comparative Example 1.

[0079] <Example 5> Spherical magnesium oxide was obtained by the same method as in Example 1, except that silicon dioxide (special grade, manufactured by Kanto Chemical Co., Ltd.) was added so that the silicon content in the final spherical magnesium oxide was 700 ppm, and the calcination temperature was set to 1600°C.

[0080] <Example 6> Spherical magnesium oxide was obtained by the same method as in Example 1, except that silicon dioxide (special grade, manufactured by Kanto Chemical Co., Ltd.) was added so that the silicon content in the final spherical magnesium oxide was 11,500 ppm, and the calcination temperature was set to 1600°C.

[0081] <Example 7> Spherical magnesium oxide was obtained by the same method as in Example 1, except that sodium tripolyphosphate (Kanto Chemical Co., Ltd., Grade 1) was added instead of silicon dioxide so that the phosphorus content in the final spherical magnesium oxide was 1,200 ppm, and the calcination temperature was set to 1600°C.

[0082] <Example 8> Spherical magnesium oxide was obtained by the same method as in Example 1, except that instead of adding silicon dioxide, manganese chloride tetrahydrate (special grade, manufactured by Kanto Chemical Co., Ltd.) was added so that the manganese content in the final spherical magnesium oxide was 9,000 ppm, and the calcination temperature was set to 1600°C.

[0083] <Example 9> Spherical magnesium oxide was obtained by the same method as in Example 1, except that instead of adding silicon dioxide, yttrium nitrate hexahydrate (high-purity reagent manufactured by Kanto Chemical Co., Ltd.) was added so that the yttrium content in the final spherical magnesium oxide was 4,500 ppm, and the calcination temperature was set to 1600°C.

[0084] <Result> The spherical magnesium oxide samples from Examples 5-9 were measured and evaluated in the same manner as in Examples 1-4 and Comparative Example 1. The results are shown in Table 2 below. The content of each element belonging to the third and fourth periods of the periodic table, other than those shown in Table 2, was 10 ppm or less in all cases.

[0085] [Table 2]

[0086] As is clear from Table 2, the spherical magnesium oxides of Examples 5-9 exhibited high sphericity and excellent moisture resistance.

[0087] From this, it was found that the spherical magnesium oxide of the present invention has high sphericity and excellent moisture resistance. Therefore, it was found that the spherical magnesium oxide of the present invention is useful as an excellent resin filler. [Industrial applicability]

[0088] The spherical magnesium oxide of the present invention is useful as an excellent resin filler because it has high sphericity and excellent moisture resistance.

Claims

1. The total content of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) and yttrium is 500 to 12,000 ppm, the boron content is less than 10 ppm, and the volume-based cumulative 50% particle size (D) is determined by laser diffraction scattering particle size distribution measurement. ５０ Spherical magnesium oxide characterized by having a diameter in the range of 1 to 200 μm and a sphericity readable from SEM images of 1.00 to 1.

20.

2. The total content of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) is 500 to 12,000 ppm, the boron content is less than 10 ppm, and the volume-based cumulative 50% particle size (D) is determined by laser diffraction scattering particle size distribution measurement. ５０ Spherical magnesium oxide characterized by having a diameter in the range of 1 to 200 μm and a sphericity readable from SEM images of 1.00 to 1.

20.

3. The spherical magnesium oxide according to claim 1 or 2, wherein the element belonging to the third or fourth period of the periodic table is at least one selected from the group consisting of sodium, aluminum, silicon, phosphorus, chlorine, potassium, and titanium.

4. Spherical magnesium oxide according to claim 1 or 2, wherein the lithium content is less than 15 ppm.

5. Spherical magnesium oxide according to claim 1 or 2, wherein the calcium content is less than 700 ppm.

6. Cumulative 50% particle diameter (D ５０ The spherical magnesium oxide according to claim 1 or 2, wherein the diameter is in the range of 5 to 100 μm.

7. BET specific surface area of ​​0.01 to 1.00 m² ２ Spherical magnesium oxide according to claim 1 or 2, wherein the amount is / g.

8. A resin filler containing spherical magnesium oxide as described in claim 1 or 2.

9. A resin composition containing the resin filler described in claim 8.

10. 1) A step of reacting a magnesium salt aqueous solution with a carbonate aqueous solution, and then agglomerating the resulting magnesium carbonate to obtain a spherical magnesium carbonate slurry, 2) A step of filtering, washing with water and drying the spherical magnesium carbonate slurry to obtain spherical magnesium carbonate particles, 3) A step of calcining the spherical magnesium carbonate particles to obtain spherical magnesium oxide, Includes, The resulting spherical magnesium oxide has a boron content of less than 10 ppm, a volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering particle size distribution analysis in the range of 1 to 200 μm, and a sphericity readable from SEM images of 1.00 to 1.

20. A method for producing spherical magnesium oxide, characterized in that, in at least one of the steps 1) to 3) above, the amount of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) and yttrium is adjusted so that the total content of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) and yttrium in the spherical magnesium oxide after calcination is 500 to 12,000 ppm.

11. 1) A step of reacting a magnesium salt aqueous solution with a carbonate aqueous solution, and then agglomerating the resulting magnesium carbonate to obtain a spherical magnesium carbonate slurry, 2) A step of filtering, washing with water and drying the spherical magnesium carbonate slurry to obtain spherical magnesium carbonate particles, 3) A step of calcining the spherical magnesium carbonate particles to obtain spherical magnesium oxide, Includes, The resulting spherical magnesium oxide has a boron content of less than 10 ppm, a volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering particle size distribution analysis in the range of 1 to 200 μm, and a sphericity readable from SEM images of 1.00 to 1.

20. A method for producing spherical magnesium oxide, characterized in that, in at least one of steps 1) to 3) above, the amount of elements belonging to the third and fourth periods of the periodic table (excluding elements belonging to groups 2 and 18) is adjusted so that the total content of these elements in the spherical magnesium oxide after calcination is 500 to 12,000 ppm.

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