TW202406847A - Highly pure spinel particles and production method therefor - Google Patents

Abstract

The purpose of the present invention is to provide: a highly pure metal composite oxide having excellent thermal conductivity and dielectric characteristics; and a method for efficiently producing said metal composite oxide. Specifically, the present invention is characterized by the use of spinel particles including at least magnesium atoms, aluminum atoms, and oxygen atoms, wherein the quantity of atoms other than said atoms is less than 0.27 at% and/or the number of calcium atoms relative to the sum of the number of magnesium atoms and aluminum atoms is less than 0.02 at%.

Description

High-purity spinel particles and manufacturing method thereof

The present invention relates to high-purity spinel particles and a manufacturing method thereof.

Spinel particles are complex oxides of metal elements represented by MgAl ₂ O ₄ and become _the general formula AB ₂ Protective films, fluorescent luminophores, catalyst carriers, adsorbents, photocatalysts, heat-resistant insulating materials, etc. Among them, since they have excellent thermal conductivity, they are being studied as heat dissipation fillers (Patent Document 1 and Patent Document 2).

On the other hand, in recent years, the speed and large-capacity of information and communications have rapidly expanded, and the fifth-generation mobile communication system (5G) and the sixth-generation mobile communication system (5G) have System, 6G) and other millimeter-wave band electromagnetic wave communication infrastructure has attracted attention. As a result, in order to reduce transmission losses in printed circuit boards and the like of power high-frequency devices, heat dissipation fillers with excellent dielectric properties (low dielectric constant, low dielectric loss tangent) are required.

In contrast, Patent Document 1 discloses spinel particles containing magnesium atoms, aluminum atoms, oxygen atoms, and molybdenum, and having a crystallite diameter of 220 nm or more in the [111] plane. It is reported that the crystallite diameter of the [111] plane of the obtained particles is significantly larger, and as a result, the thermal conductivity is excellent.

In addition, Patent Document 2 discloses a spinel structure whose main component is MgAl ₂ O ₄ or ZnAl ₂ O ₄ obtained by calcining a raw material containing at least an alumina-based compound and a compound of magnesium or zinc. . Specifically, it describes a thermally conductive composite oxidizer that focuses on chemical resistance and has an absolute value of mass change rate of 2% or less in chemical resistance tests against hydrochloric acid, sulfuric acid, nitric acid, and sodium hydroxide. things. [Prior Art Documents] [Patent Documents]

[Patent Document 1] International Publication No. 2017/221372 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-135841

[Problem to be solved by the invention] All documents focus on thermal conductivity or thermal conductivity and chemical resistance, and do not examine dielectric properties. In addition, the inventors believe that in order to obtain low dielectric properties in a molded article, it is important to make the spinel particles spherical in shape to improve filling properties when mixed with resin. However, producing spherical spinels There is still room for research on the method of using stone particles.

The present invention was made in view of the above-mentioned circumstances, and provides high-purity spinel particles having both high thermal conductivity and low dielectric properties and a method for producing the same. [Means to solve the problem]

The inventors of the present invention have made repeated efforts to study in order to achieve the above object, and as a result have found that spinel particles obtained by calcining high-purity magnesium-based compounds and aluminum-based compounds that are fine particles have high purity and high thermal conductivity. , excellent in dielectric properties, and completed the present invention.

That is, the present invention includes the following aspects. (1) Spinel particles containing at least magnesium atoms, aluminum atoms, and oxygen atoms, wherein the amount of atoms other than the atoms in the spinel particles is less than 0.27 atomic %. (2) Spinel particles containing at least magnesium atoms, aluminum atoms, and oxygen atoms, wherein the number of calcium atoms in the spinel particles is less than 0.02 atomic % relative to the sum of the numbers of magnesium atoms and aluminum atoms. (3) The spinel particles according to (1) or (2) above, wherein the average particle diameter is 75 μm or less. (4) The spinel particles according to any one of (1) to (3) above, wherein the dielectric loss tangent at 1 GHz is less than 1.0×10 ^-3 . (5) A resin composition comprising the spinel particles and resin according to any one of (1) to (4). (6) A molded article of the resin composition described in (5). (7) A method for producing spinel particles, in which an aluminum-based compound and a magnesium-based compound are mixed and calcined, wherein the magnesium-based compound has an average particle diameter of less than 4 μm. The amount of impurities contained in the magnesium-based compound is less than 1.0 atomic %. (8) A method for producing spinel particles, in which an aluminum-based compound and a magnesium-based compound are mixed and calcined, wherein the magnesium-based compound has an average particle diameter of less than 4 μm. of microparticles, and the calcium atomic weight contained in the magnesium-based compound is 0.6 atomic % or less. (9) The manufacturing method according to (7) or (8), wherein the shape of the aluminum-based compound is spherical or spherical. [Effects of the invention]

According to the present invention, spinel particles are highly purified compared to conventional spinel particles, and are spinel particles excellent in both thermal conductivity and dielectric properties. In addition, the spinel particles of the present invention can be easily obtained by mixing and calcining a magnesium-based compound and an aluminum-based compound that are fine particles and of high purity, so the productivity is high and the practicality is excellent.

Hereinafter, modes for implementing the present invention will be described in detail. ＜Spinel particles＞ One embodiment of the spinel particles of the present invention is a spinel particle containing at least a magnesium atom, an aluminum atom, and an oxygen atom. The spinel particle is characterized in that the amount of atoms other than the above-mentioned atoms is relatively small. It is less than 0.27 atomic % based on the atomic number of spinel particles.

One embodiment of the spinel particles of the present invention is a spinel particle containing at least magnesium atoms, aluminum atoms, and oxygen atoms. The spinel particles are characterized in that the number of calcium atoms relative to the number of magnesium atoms and The total number of aluminum atoms is less than 0.02 atomic %.

The spinel particles are spinel particles containing at least magnesium atoms, aluminum atoms and oxygen atoms, and the amount of other atoms is less than 0.27 atomic %, more preferably less than 0.2 atomic %, and particularly preferably less than 0.1 atomic %. If the upper limit is less than the above-mentioned upper limit, the obtained spinel particles will have excellent dielectric properties, which is preferable.

Spinel particles are spinel particles containing at least magnesium atoms, aluminum atoms, and oxygen atoms, and the number of calcium atoms relative to the sum of the numbers of magnesium atoms and aluminum atoms is less than 0.02 atomic %, and more preferably less than 0.02 atomic %. 0.01 atomic %, preferably less than 0.005 atomic %. If the upper limit is less than the above-mentioned upper limit, the obtained spinel particles will have excellent dielectric properties, which is preferable.

The average particle diameter of the spinel particles is preferably 75 μm or less, more preferably 35 μm or less, and particularly preferably 10 μm or less. If the particle size is less than or equal to the above-mentioned particle size, it is preferable because the surface of the processed product will not become uneven when mixed with a resin and processed into sheets or the like.

In this specification, the "average particle size" of spinel particles means, for example, the use of a laser diffraction and scattering particle size distribution measuring device MT3300EXII (manufactured by Microtrac Bell Co., Ltd.) The value measured based on the particle size distribution system of laser diffraction and scattering, and expressed as D50.

In addition, the average particle diameter can also be used as the longest diameter (the longest diameter) identified from the particle image of the primary particles of the spinel particles in a two-dimensional image captured with a scanning electron microscope (SEM). diameter: the arithmetic mean of the longest distance between each particle when two parallel line segments are sandwiched between each particle in the observation field of view or on the image), and the obtained value represents a value that is approximately equivalent to the measured value obtained by the above method. value. In addition, the spinel particles to be measured are at least fifty spinel particles randomly selected from those who can recognize the entire image of the contour line.

The dielectric constant of the spinel particles is preferably 20 or less, more preferably 15 or less, and particularly preferably 10 or less. If it is within the above range, it is preferable because power consumption, that is, heat generation or noise can be suppressed when the resin composition is formed.

The dielectric loss tangent of the spinel particles at 1 GHz is preferably 1.0×10 ^-3 or less, more preferably 8.0×10 ^-4 or less, and particularly preferably 5.0×10 ^-4 or less. If it is within the above range, it is preferable because power consumption, that is, heat generation or noise can be suppressed when the resin composition is formed.

Examples of the shape of spinel particles include: polyhedral, spherical, spherical, elliptical, cylindrical, polygonal prism, needle, rod, plate, disk, flake, scale, etc. . Among them, a spherical shape is preferable because the filling property becomes high when mixed with a resin. If it is a perfect spherical shape, the viscosity of the mixture further decreases, the filling rate increases, and the densest packing structure is easily achieved. Therefore, Excellent.

When spinel particles having a spherical shape are included, it is preferable that 50% or more of the particles have a spherical shape on a mass basis or a number basis, and more preferably 80% or more of the particles have a spherical shape. The shape, preferably more than 90% of the particles, has a spherical shape.

Furthermore, if the shape is spherical or spherical, the resin composition will be packed tightly in order to easily avoid contact and fixation with other particles during molding. In addition, by adopting the above shape, the fractal dimension of the particle outline is reduced, and the space ratio during filling is suppressed. As a result, it is provided with excellent thermal conductivity and dielectric properties by adopting the densest packing structure.

In this specification, the shape is judged by visual inspection from a scanning electron microscope (SEM) image, but the circularity can also be calculated and judged. For example, the circularity may be 0.7 or more, and may be 0.75 or more or 0.8 or more. In addition, the "circularity" can be calculated from "4×π×area/circumference^2", and the area and the circumference can be determined by observation using a scanning electron microscope (SEM).

The crystal structure of the spinel particles is MgAl ₂ O ₄ having a spinel type crystal structure. In addition, the spinel particles of this embodiment described below mainly have a spinel type crystal structure, but may contain an impurity phase to an extent that does not adversely affect the dielectric loss tangent.

<Content of each atom> (Magnesium atom) The content of magnesium atoms in the spinel particles is not particularly limited. However, when the structural formula of the spinel particles is represented by Mg _x Al _y O _z , x is preferably The range is 0.8~1.2, and the range of 0.9~1.1 is more preferable. In addition, in this specification, the content of magnesium atoms in the spinel particles adopts a value measured by a fluorescent X-ray elemental analysis method (X-ray fluorescent analysis (XRF)).

(Aluminum Atom) The content of aluminum atoms in the spinel particles is not particularly limited. However, when the structural formula of the spinel particles is represented by Mg _x Al _y O _z , y is preferably in the range of 1.8 to 2.2. More preferably, it is in the range of 1.9 to 2.1. In addition, in this specification, the content of the aluminum atom in the spinel particle adopts the value measured by X-ray fluorescence elemental analysis (XRF).

(Oxygen atom) The content of oxygen atoms in the spinel particles is not particularly limited. However, when the structural formula of the spinel particles is represented by Mg _x Aly _{O z} , z is preferably (x+y+1.2 ) to (x+y+0.8), more preferably (x+y+1.1) to (x+y+0.9).

(other atoms) The so-called other atoms refer to substances that are present in the raw materials or are inevitably mixed into the spinel particles during the manufacturing process. They are substances that are not originally necessary and impurities that affect the characteristics of the spinel particles.

Other atoms in the spinel particles are not particularly limited, and examples include silicon, iron, potassium, sodium, calcium, and the like. These impurities may be contained individually or may contain two or more types, but their content is preferably less than 0.27 atomic % relative to the atoms of the spinel particles. If it is within the above range, it is assumed that the scattering of phonons (lattice vibration) caused by impurities is suppressed, and thus the spinel particles have excellent dielectric properties. The content of other atoms in spinel is measured by X-ray fluorescence elemental analysis (XRF).

In the spinel particles, the number of calcium atoms as impurities is preferably less than 0.02 atomic % relative to the sum of the numbers of magnesium and aluminum atoms. If it is within the above range, it is presumed that the scattering of phonons (lattice vibration) caused by impurities generated by calcium atoms substituted by magnesium atoms is suppressed, and the spinel particles have excellent dielectric loss tangent. The content of calcium atoms in the spinel particles is a value measured by X-ray fluorescence elemental analysis (XRF).

Furthermore, in the spinel particles of the present invention, any of the content of impurities (silicon, iron, potassium, sodium, calcium, etc.) and the number of calcium atoms relative to the sum of the numbers of magnesium and aluminum atoms It is sufficient that one of them is within the above range, or both of them can be satisfied. Furthermore, if both are within the above range, it is particularly preferable because spinel particles having more excellent dielectric properties can be obtained.

＜Production method of spinel particles＞ The method for producing spinel particles includes the step of calcining a mixture containing a magnesium-based compound and an aluminum-based compound.

[Mixing step] The mixing step is a step of mixing a magnesium-based compound and an aluminum-based compound to obtain a mixture. At this time, the mixing state of the magnesium-based compound and the aluminum-based compound is not particularly limited. When mixing the two, simple mixing is performed by placing the raw materials in a bag or the like and shaking to mix the powders, mechanical mixing using a grinder or a mixer, or mixing using a mortar or the like. wait. At this time, the obtained mixture may be in either a dry state or a wet state, but from the viewpoint of cost, a dry state is preferred.

In the mixing step, the mixing ratio of the magnesium-based compound and the aluminum-based compound is not particularly limited. It is preferable that the molar ratio of the aluminum element of the aluminum-based compound to the magnesium element of the magnesium-based compound (aluminum element/magnesium element) is It is mixed so that it may become 1.8 or more and 2.2 or less, and it is more preferable to mix so that it may become 1.9 or more and 2.1 or less. The contents of the mixture will be described below.

(magnesium-based compounds) The magnesium-based compound is not particularly limited, and examples thereof include metallic magnesium, magnesium derivatives, magnesium oxoates, magnesium organic salts, and hydrates thereof. Examples of magnesium derivatives include magnesium oxide, magnesium hydroxide, magnesium peroxide, magnesium fluoride, magnesium chloride, magnesium bromide, magnesium iodide, magnesium hydride, magnesium diboride, magnesium nitride, magnesium sulfide, and the like. Examples of the magnesium oxo acid salt include magnesium carbonate, calcium magnesium carbonate, magnesium nitrate, magnesium sulfate, magnesium sulfite, magnesium perchlorate, tripomagnesium phosphate, magnesium permanganate, magnesium phosphate, and the like. Examples of magnesium organic salts include magnesium acetate, magnesium citrate, magnesium malate, magnesium glutamate, magnesium benzoate, magnesium stearate, magnesium acrylate, magnesium methacrylate, magnesium gluconate, and magnesium naphthenate. , magnesium salicylate, magnesium lactate, magnesium monoperoxyphthalate, etc. In addition, these magnesium-based compounds may be used alone or in combination of two or more.

Among them, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium acetate, magnesium nitrate or magnesium sulfate is preferred, and magnesium oxide, magnesium hydroxide, magnesium nitrate or magnesium acetate is more preferred.

The volume-based average particle diameter D50 in the laser diffraction particle size distribution measurement of magnesium compounds is used within a range that does not agglomerate, and the smaller particle diameter is used to achieve homogenization during calcination and obtain a more consistent particle size. of spinel particles. The average particle diameter D50 is 0.01 μm or more and less than 4 μm, more preferably 0.1 μm or more and 2 μm or less, still more preferably 0.5 μm or more and 2 μm or less, particularly preferably 0.5 μm or more and 1.5 μm or less. . If it is the said lower limit value or more, aggregation of particle|grains during mixing can be suppressed. If it is less than the upper limit, magnesium atoms can be diffused into the aluminum-based compound particles without destroying the shape of the aluminum-based compound, and particles with regular shapes can be grown.

Magnesium compounds can be commercially available or can be prepared by oneself. When the magnesium-based compound is prepared by oneself, the reactivity for producing spinel particles can be adjusted. For example, magnesium hydroxide with a small particle size can be obtained by neutralizing an acidic aqueous solution of magnesium ions with a base. Since the magnesium hydroxide obtained with a small particle size has high reactivity, the crystallite diameter of the spinel particles obtained using the magnesium hydroxide tends to become larger.

Commercially available or prepared magnesium compounds may contain impurities such as silicon, iron, potassium, sodium, calcium, phosphorus, sulfur, and chlorine. The total amount of these impurities is preferably less than 1.0 atomic % and more preferably 0.5 atomic % relative to magnesium when the value measured by fluorescence X-ray elemental analysis (XRF) is converted into the number of atoms. % or less, more preferably 0.3 atomic % or less.

The calcium atomic weight contained in the magnesium compound of a commercial product or a prepared product is preferably 0.6 atomic % or less, more preferably 0.4 atomic % or less, and still more preferably 0.3 atomic % or less.

(Aluminum-based compounds) The aluminum-based compound is not particularly limited, and examples thereof include aluminum such as metallic aluminum, aluminum oxide, aluminum hydroxide, aluminum sulfide, aluminum nitride, aluminum fluoride, aluminum chloride, aluminum bromide, and aluminum iodide. Derivatives; aluminum oxysates such as aluminum sulfate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum ammonium sulfate, aluminum nitrate, aluminum perchlorate, aluminum aluminate, aluminum silicate, aluminum phosphate; aluminum acetate, aluminum lactate, laurel Aluminum organic salts such as aluminum acidate, aluminum stearate, and aluminum oxalate; aluminum alkoxides such as aluminum propoxide and aluminum butoxide; aluminum-magnesium-containing compounds such as magnesium aluminate, hydrotalcite, and magnesium aluminum isopropoxide ; And these hydrates, etc. Among these, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and hydrates of these are preferably used, and aluminum oxide and aluminum hydroxide are more preferably used. In addition, the aluminum-based compounds may be used alone or in combination of two or more.

The volume-based average particle diameter D50 in the laser diffraction particle size distribution measurement of aluminum-based compounds is used within a range that does not agglomerate, and the smaller particle diameter can be used to improve the reactivity during calcination and obtain impurities-free products. Spinel particles with high phase purity are preferred. The particle size of the aluminum raw material is related to the particle size of the obtained spinel particles, so it is appropriately selected based on the desired particle size of the spinel particles. The average particle diameter D50 of the aluminum-based compound is 0.01 μm to 70 μm, preferably 0.1 μm to 30 μm, more preferably 0.1 μm to 15 μm, most preferably 0.5 μm to 10 μm. the following.

In order to obtain the average particle diameter D50, the aluminum-based compound as a raw material may be pulverized and adjusted using a pulverizer or the like. Furthermore, from the viewpoint of the particle shape of the aluminum-based compound described below and the shape of the obtained spinel particles, it is more preferable to use an aluminum-based compound that does not require pulverization for particle size adjustment as a raw material.

The shape of the aluminum-based compound can be any one of polyhedron, spherical, spherical, elliptical, cylindrical, polygonal prism, needle, rod, plate, disc, flake, and scale. However, from the viewpoint of the shape of the spinel particles obtained, spherical or spherical shapes are more preferred. According to the manufacturing method of this embodiment, magnesium atoms diffuse into the aluminum-based compound particles. Therefore, the aluminum-based compound as a raw material can be grown without collapsing its shape during particle growth, and the obtained spinel can be easily modified. Control the shape of stone particles.

The crystal structure of the aluminum-based compound is not particularly limited and may be a single phase or a mixed phase. Furthermore, when the crystal structure is a mixed phase, the shape of the aluminum-based compound is often spherical.

[Calcination step] By calcining the mixture at high temperature in a calcining furnace, spinel particles can be obtained.

The calcination temperature is not particularly limited as long as desired spinel particles can be obtained, but it is preferably 1100°C to 1600°C, more preferably 1200°C to 1500°C, and particularly preferably 1300°C to 1400°C. If the calcining temperature is 1100°C or higher, unreaction of raw materials is suppressed, so it is preferable. On the other hand, if the calcining temperature is 1600°C or lower, a general-purpose calcining furnace can be used, so it is better in terms of mass production adaptability. good.

The calcination time is not particularly limited, but is preferably 1 to 20 hours, more preferably 5 to 10 hours. The calcination time is preferably 1 hour or more because highly crystalline spinel particles can be obtained. On the other hand, if the calcination time is within 20 hours, the manufacturing cost may be reduced, so it is preferable.

The calcination environment can be an air environment, an inert gas environment such as nitrogen or argon, an oxygen environment, an ammonia environment, or a carbon dioxide environment. At this time, from the viewpoint of manufacturing cost, an air environment is preferable.

The pressure during calcination is not particularly limited. It may be carried out under normal pressure, under increased pressure, or under reduced pressure. However, from the viewpoint of manufacturing cost, it is preferably under Carry out under normal pressure.

The heating means is not particularly limited, but a calcining furnace is preferably used. Examples of calcining furnaces that can be used at this time include box furnaces, tunnel furnaces, roller hearth furnaces, rotary kilns, muffle furnaces, and the like.

Compared with the production method using a general flame method or the like, in this production method, it is considered that during particle growth, magnesium atoms do not diffuse on the surface or at the particle boundary, but proceed within the aluminum-based compound particles as a diffusion path. As a result of volume diffusion, it is assumed that particles can be grown while maintaining the shape of the aluminum-based compound as the raw material. In addition, the production method of the present invention does not require pretreatment such as adsorbing magnesium atoms to the surface of the aluminum-based compound, and therefore is a production method with excellent productivity.

[Cooling step] The cooling step is a step of cooling the spinel particles whose crystals have grown in the calcining step and crystallizing them into a particle form.

The cooling rate is not particularly limited, but it is preferably 1°C/hour to 1000°C/hour, more preferably 5°C/hour to 500°C/hour, and still more preferably 100°C/hour to 500°C/hour. If the cooling rate is 1° C./hour or more, the manufacturing time can be shortened, which is preferable. On the other hand, if the cooling rate is 1000° C./hour or less, the calcining container is less likely to be broken due to thermal shock and can be used for a long period of time, which is preferable. The cooling method is not particularly limited and may be natural cooling or a cooling device.

The manufacturing method of the present invention may also include post-processing steps. This post-processing step is a step of removing additives and the like. The post-treatment step may be performed after the calcining step, or after the cooling step, or after the calcining step and the cooling step. In addition, the process can be repeated two or more times as necessary.

Examples of post-processing methods include cleaning and high-temperature treatment. These can be combined. The cleaning method is not particularly limited. For example, it can be removed by cleaning with water, an ammonia aqueous solution, a sodium hydroxide aqueous solution, an acidic aqueous solution, or the like. Examples of high-temperature treatment methods include raising the temperature to a level higher than the sublimation point or boiling point of the additive.

[Crushing steps] The agglomeration of spinel particles obtained by calcination may not satisfy the preferable particle diameter range in the present invention. In this case, it may be pulverized as necessary so as to satisfy the preferable particle diameter range in the present invention.

The method of grinding is not particularly limited, and conventionally known grinding methods such as ball mills, jaw crushers, jet mills, disc mills, spectro mills, grinders, and mixers can be used.

[grading steps] The spinel particles may be classified in order to adjust the average particle size, improve the fluidity of the powder, or suppress an increase in viscosity when blended into a binder used to form a matrix. The so-called "classification processing" refers to the operation of grouping particles according to their size.

The classification method may be either a wet type or a dry type, but from the viewpoint of productivity, dry classification is preferred. In addition to classification using sieves, dry classification also includes wind classification, which classifies based on the difference between centrifugal force and fluid resistance. From the perspective of classification accuracy, wind classification is preferred, and air flow classification utilizing the Coanda effect can be used. Classifiers such as machine, vortex airflow classifier, forced vortex centrifugal classifier, semi-free vortex centrifugal classifier, etc.

The grinding step or classification step described above can be performed at necessary stages including before and after the organic compound layer forming step described later. For example, the average particle diameter of the obtained particles can be adjusted by the presence or absence of the crushing or classification or by selecting the conditions.

＜Resin composition＞ According to one aspect of the present invention, a composition containing spinel particles and resin is provided. At this time, the composition may further include a hardener, a hardening catalyst, a viscosity regulator, a plasticizer, etc. as needed.

(spinel particles) As the spinel particles, those described in the above-mentioned “spinel particles” can be used, so the description is omitted here.

Furthermore, as the spinel particles, those surface-treated by the method described below can also be used. By performing surface treatment, the thermal conductivity of the spinel particles can be further improved. For example, by attaching a surface treatment layer containing an organic compound to at least a part of the surface of the spinel particles obtained as described above, the surface-treated spinel particles can be produced.

By making the surface treatment layer adhere to at least part of the surface of the untreated spinel particles, the wettability with the resin contained in the resin composition is improved, and the adhesion with the spinel particles is improved, so it is easy to The generation of voids generated on the surface of the spinel particles is suppressed, so the loss in thermal conductivity is reduced. Therefore, for example, the thermal conductivity of a molded article of the resin composition can be improved. This technical effect is achieved by adhering a surface treatment agent based on an organic compound or a surface treatment layer based on a hardened product thereof to a part of the surface of the spinel particles. For example, calcining is performed after the surface treatment to change the surface. When the treatment agent is removed from the spinel particles, it cannot appear.

In addition, when using a plurality of types of spinel particles, spinel particles having a surface treatment layer may be used as one or more types of the plurality of types.

Specifically, the untreated spinel particles can be mixed with a surface treatment agent capable of forming a surface treatment layer containing an organic compound, and the surface treatment agent can be adhered to the surface of the untreated spinel particles. After at least a part of it is dried or hardened, for example, surface-treated spinel particles are produced.

When the surface treatment agent itself is a non-reactive but adsorbent organic compound, or the surface treatment agent is a solution or dispersion dissolved or dispersed in a liquid medium, as long as the purpose is to promote adsorption or removal of the liquid medium. It suffices to dry for the purpose. When the surface treatment agent is a reactive organic compound, the surface treatment layer can be formed by hardening based on the reactive group of the compound. Furthermore, when the surface treatment agent is allowed to adhere to the entire surface of the untreated spinel particles, the untreated spinel particles are covered with the surface treatment layer.

As the surface treatment agent, a nonpolar silane compound is preferred. If it is non-polar, it does not have a polar substituent, and therefore the deterioration of the dielectric properties can be suppressed. The polar substituent refers to a group capable of hydrogen bonding or an ionic dissociating group. The polar substituent is not particularly limited, and examples thereof include -OH, -COOH, -COOM, -NH ₃ , -NR ₄ ⁺ A ^- , -CONH ₂ and the like. Here, M is a cation such as an alkali metal, alkaline earth metal, or quaternary ammonium salt, R is H or a hydrocarbon group having 8 or less carbon atoms, and A is an anion such as a halogen atom.

The treatment method of the surface treatment agent can be carried out by a known and commonly used method. For example, a spray method using a fluid nozzle, agitation with shear force, a dry method such as a ball mill or a mixer, or a wet method such as a water-based or organic solvent-based method can be used. Formula. Surface treatment using shear force is ideally performed to an extent that does not cause damage to the filler.

In addition, the system temperature in the dry method of the surface treatment agent or the temperature of drying or hardening after treatment in the wet method is appropriately determined in a region where thermal decomposition does not occur depending on the type of the surface treatment agent. For example, it is desirable to heat at a temperature of 80°C to 230°C.

The amount of non-volatile components or hardened matter of the surface treatment agent in the surface treatment layer relative to the untreated spinel particles is not particularly limited, but in terms of improving functions such as thermal conductivity, it is preferable to use untreated spinel particles. The spinel particles are processed so that the non-volatile components or hardened materials in the surface treatment agent are 0.01 to 10 parts per 100 parts in terms of mass conversion.

Whether the unknown spinel particles are equivalent to the surface-treated spinel particles of the present invention can be confirmed by, for example, the following operations: whether infrared absorption analysis (Infrared Spectroscopy, IR) or atomic absorption spectroscopy (Atomic Absorption Spectroscopy) can be used. AAS) When the unknown spinel particles are immersed in a solvent that dissolves the non-volatile components or hardened materials of the surface treatment agent, or are extracted by boiling, or the surface of the spinel particles itself is observed to be consistent with the surface The chemical structure corresponding to the treatment agent itself or its hardened product or the presence of silicon atoms, titanium atoms or phosphorus atoms.

(resin) The resin is not particularly limited, and examples include thermoplastic resin, thermosetting resin, and the like.

The thermoplastic resin is not particularly limited, and any known and commonly used resin used in molding materials and the like can be used. Specific examples include polyethylene resin, polypropylene resin, polymethyl methacrylate resin, polyvinyl acetate resin, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride resin, poly Styrene resin, polyacrylonitrile resin, polyamide resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polyphenylene ether resin, polyphenylene sulfide resin, polystyrene resin, Polyether resin, polyether ether ketone resin, polyallyl resin, thermoplastic polyimide resin, thermoplastic urethane resin, polyamine bismaleimide resin, polyamide imide resin Resin, polyether imide resin, bismaleimide triazine resin, polymethylpentene resin, fluorinated resin, liquid crystal polymer, olefin-vinyl alcohol copolymer, ionomer resin, polyarylate resin , acrylonitrile-ethylene-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, etc.

The thermosetting resin is a resin that has the property of becoming substantially insoluble and infusible when cured by means such as heating, radiation, or a catalyst. Generally, those used in molding materials and the like can be used. Commonly used resins are known. Specific examples thereof include: phenol resin, epoxy resin, urea resin, resin having a triazine ring, (meth)acrylic resin, vinyl resin, unsaturated polyester resin, bismaleimide resin, Polyurethane resin, diallyl phthalate resin, silicone resin, resin with benzoxazine ring, cyanate ester resin, etc. Examples of the phenol resin include novolac-type phenol resin, resol-type phenol resin, and the like. Examples of the novolac-type phenol resin include phenol novolak resin, cresol novolac resin, and the like. Examples of the resol-type phenol resin include unmodified resol phenol resin, oil-modified resol phenol resin, and the like. Examples of oils used for oil modification include tung oil, linseed oil, walnut oil, and the like. Examples of the epoxy resin include bisphenol-type epoxy resin, aliphatic chain-modified bisphenol-type epoxy resin, novolak-type epoxy resin, biphenyl-type epoxy resin, polyolefin glycol-type epoxy resin, and the like. Examples of the bisphenol-type epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, and the like. Examples of the novolak-type epoxy resin include novolac epoxy resin, cresol novolac epoxy resin, and the like. Examples of the resin having a triazine ring include melamine resin and the like. Examples of the vinyl resin include vinyl ester resin and the like.

The resins may be used alone or in combination of two or more. In this case, two or more thermoplastic resins may be used, two or more thermosetting resins may be used, or one or more thermoplastic resins and one or more thermosetting resins may be used.

(hardener) The hardener is not particularly limited, and known hardeners can be used. Specific examples of the curing agent include amine compounds, amide compounds, acid anhydride compounds, phenol compounds, and the like.

Examples of the amine compound include: diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminediphenylthione, isophoronediamine, imidazole, BF ^3- amine complexes, guanidine derivatives, etc.

Examples of the amide-based compound include a polyamide resin synthesized from a dimer of dicyandiamine, linolenic acid, and ethylenediamine.

Examples of the acid anhydride-based compound include phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, maleic anhydride, tetrahydrophthalic anhydride, and methyltetrahydrophthalic anhydride. , methyl nadic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, etc.

Examples of the phenolic compound include: phenol novolac resin, cresol novolak resin, aromatic hydrocarbon formaldehyde resin modified phenolic resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin (new phenolic resin) (Xylok) resin), polyvalent phenol novolak resin represented by resorcinol novolac resin, which is synthesized from polyvalent hydroxyl compounds and formaldehyde, naphthol aralkyl resin, trimethylolmethane resin, tetrahydroxyphenyl alcohol Alkane resin, naphthol novolac resin, naphthol-phenol novolak resin, naphthol-cresol novolak resin, biphenyl modified phenol resin (which uses bismethylene to link phenol cores) Polyphenol compound), biphenyl-modified naphthol resin (polymeric naphthol compound with phenol core linked by bismethylene), aminotriazine-modified phenol resin (linked by melamine, benzoguanamine, etc. Polyphenol compounds such as polyphenol compounds having a phenol core), alkoxy-containing aromatic ring-modified phenolic resins (polyphenol compounds having a phenol core and an alkoxy-containing aromatic ring linked by formaldehyde), etc.

The hardener may be used alone or in combination of two or more.

(hardening accelerator) The hardening accelerator has the function of accelerating hardening when the resin composition is hardened. The hardening accelerator is not particularly limited, and examples thereof include phosphorus compounds, tertiary amines, imidazole, organic acid metal salts, Lewis acids, amine complex salts, and the like. The hardening accelerator may be used alone or in combination of two or more.

The curing catalyst has a function of causing the compound having a polymerizable functional group to undergo a curing reaction instead of the curing agent. The curing catalyst is not particularly limited, and a commonly used thermal polymerization initiator or active energy ray polymerization initiator can be used. Furthermore, the hardening catalyst can be used alone or in combination of two or more types.

(viscosity regulator) The viscosity modifier has the function of adjusting the viscosity of the resin composition. The viscosity modifier is not particularly limited, and for example, organic polymers, polymer particles, inorganic particles, etc. can be used. The viscosity regulator can be used alone or in combination of two or more.

(Plasticizer) Plasticizers have the function of improving the processability, softness, and weather resistance of thermoplastic synthetic resins. The plasticizer is not particularly limited, and examples thereof include phthalate esters, adipate esters, phosphate esters, trimellitate esters, polyesters, polyolefins, and polysiloxanes. The plasticizer can be used alone or in combination of two or more.

[mix] The resin composition of the present invention is obtained by mixing spinel particles, resin, and other formulations as necessary. The mixing method is not particularly limited, and mixing is performed by a known and commonly used method. When the resin is a thermosetting resin, a general mixing method of the thermosetting resin and spinel particles may include the following method: a predetermined amount of the thermosetting resin is mixed with a mixer or the like. , and spinel particles, and other components as necessary are thoroughly mixed, and then kneaded using three rollers, etc., to obtain a fluid liquid composition. In addition, as a method of mixing the thermosetting resin and spinel particles in other embodiments, a method is as follows: using a mixer or the like, a predetermined amount of the thermosetting resin and spinel particles are mixed. After the required other components are sufficiently mixed, the mixture is melted and kneaded using a mixing roll, an extruder, etc., and then cooled to obtain a solid composition. Regarding the mixing state, when preparing a hardening agent, catalyst, etc., it is sufficient to fully and uniformly mix the curable resin and these preparations, but it is more preferable to also disperse and mix the spinel particles uniformly. .

Furthermore, the content of the spinel particles relative to the volume of the resin composition is preferably 5 volume % or more and 95 volume % or less, more preferably 20 volume % or more and 90 volume % or less, and particularly preferably 30 volume % or more. And 80% capacity. If the content of spinel particles is equal to or higher than the lower limit, more excellent thermal conductivity and dielectric properties can be imparted to the resin composition. On the other hand, when the content of spinel particles is equal to or less than the upper limit, fluidity is excellent and molding can be easily performed.

When the resin is a thermoplastic resin, a general method of mixing the thermoplastic resin and spinel particles or the like is to use various mixers such as a drum or a Henschel mixer to mix the thermoplastic resin, spinel particles and other components as necessary. After the ingredients are mixed in advance, melt and kneading is performed using mixers such as Brabender mixers, rollers, Brabender mixers, single-shaft kneading extruders, twin-shaft kneading extruders, kneaders, and mixing rollers. Methods. In addition, the temperature of melting and kneading is not particularly limited, but is usually in the range of 100°C or more and 320°C or less. In order to further improve the fluidity of the resin composition or the fillability of fillers such as spinel particles, a coupling agent may be additionally added to the resin composition. Furthermore, by adding a coupling agent, the adhesion between the resin and the spinel particles can be further improved, and the interface thermal resistance between the resin and the spinel particles can be reduced, thereby improving the thermal conductivity of the resin composition.

Examples of the coupling agent include organosilane compounds and the like.

Examples of the organosilane compound include methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, N-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, pentyltrimethoxysilane, hexyltrimethoxysilane, octenyltrimethoxysilane and other alkyl groups Alkyltrimethoxysilanes with a carbon number of 1 to 22; 3,3,3-trifluoropropyltrimethoxysilane; tridecafluoro-(1,1,2,2-tetrahydrooctyl) Trichlorosilane and other alkyltrichlorosilanes with an alkyl group having a carbon number of 1 to 22; phenyltrimethoxysilane, phenyltriethoxysilane, p-chloromethylphenyltrimethoxysilane, p- Chloromethylphenyltriethoxysilane; γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl )Ethyltrimethoxysilane, glycidoxyoctyltrimethoxysilane and other epoxysilanes; γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-amino Propyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxy Aminosilanes such as silane; mercaptosilanes such as 3-mercaptopropyltrimethoxysilane; p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy) Vinyl silanes such as silane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, methacryloxyoctyltrimethoxysilane; Further examples include epoxy-based, amine-based, and vinyl-based polymer type silanes. Furthermore, the organosilane compound may be contained alone or two or more kinds thereof.

The amount of coupling agent added is not particularly limited, but is preferably 0.01 mass % or more and 5 mass % or less, and more preferably 0.1 mass % or more and 3 mass % or less based on the mass of the resin.

＜Use＞ According to one embodiment of the present invention, the resin composition of the present invention is used as a low-dielectric heat dissipation material. Generally speaking, as a thermally conductive material, aluminum oxide is often used from the viewpoint of cost. In addition, boron nitride, aluminum nitride, magnesium oxide, magnesium carbonate, etc. are also used. However, among these materials, for example, aluminum oxide has insufficient dielectric properties, boron nitride has anisotropy derived from the crystal structure, so uniform dielectric properties cannot be obtained in the resin composition, aluminum nitride, oxide Magnesium and magnesium carbonate have low water resistance and therefore have insufficient dielectric properties. Therefore, no material has been found that has both thermal conductivity and dielectric properties.

In contrast, the spinel particles of the present invention have unprecedented high purity and therefore have both excellent thermal conductivity and dielectric properties. The resin composition containing the spinel particles is preferably used for low dielectric Electric heat dissipation material. In addition, when the shape of the spinel particles of the present invention is spherical or spherical, the anisotropy is reduced and uniform dielectric properties can be obtained in the resin composition, which is particularly preferred for low dielectric properties. Material.

The resin composition of the present invention has excellent thermal conductivity and dielectric properties, and therefore can be used as a base material/substrate such as a single-layer or multi-layer printed circuit board or a flexible printed circuit board. In addition, as an insulating material for wiring, especially high-frequency signal wiring, it can be preferably used as a cover film, solder resist, build-up material, interlayer insulating agent, bonding sheet, interlayer adhesive, flip chip Bump sheet for adapter.

In addition, spinel particles can also be used in gemstones, catalyst carriers, adsorbents, photocatalysts, optical materials, phosphors, heat-resistant insulating materials, substrates, sensors, etc.

According to one aspect of the present invention, a molded article obtained by molding the resin composition is provided. The spinel particles of the present invention contained in the molded article have excellent thermal conductivity and dielectric properties, so the molded article is preferably used as a low-dielectric heat dissipation member. In this way, the heat dissipation function of the device can be improved, which not only contributes to the compactness, weight reduction and high performance of the device, but also contributes to the high functionality of communication functions in high-frequency circuits. [Example]

Hereinafter, the present invention will be described in further detail based on examples, but this description does not limit the present invention. In the examples, unless otherwise stated, all values are based on atomic number conversion.

(Analysis of the amount of elements contained in magnesium-based compounds used as raw materials) Composition analysis was performed using a fluorescence X-ray analyzer Supermini 200 (manufactured by Rigaku Co., Ltd.) and using approximately 5 g of a magnesium-based compound. Using the XRF analysis results, for elements other than oxygen, the amount of impurities is calculated based on the molar ratio (number of atoms). That is, let the impurity amount (atomic %) = (number of atoms other than Mg)/(number of atoms of Mg) × 100. Similarly, Ca is set to Ca impurity amount (atomic %) = (number of atoms of Ca)/(number of atoms of Mg) × 100.

(Synthesis of spinel particles) <Example 1> Using an Absolute Mill (manufactured by Osaka Chemical Co., Ltd.), 70 g of alumina particles (manufactured by DENKA Co., Ltd., DAW-05, spherical, average particle diameter 6.4 μm) were mixed with magnesium hydroxide (Kyowa Chemical Co., Ltd. A mixture was obtained by mixing 40 g of KISMA 5Q-S manufactured by Industrial Co., Ltd. (average particle diameter: 0.66 μm, no detectable impurity amount, total impurity amount: 0.13 atomic %). The obtained mixture was put into a crucible, heated to 1300°C using a ceramic electric furnace at 5°C/min, and calcined while maintaining at 1300°C for 10 hours. Then, after cooling to room temperature at 5° C./min, the crucible was taken out, and about 90 g of white powder was obtained.

<Example 2> The same procedure as in Example 1 was performed except that the calcination temperature was changed to 1400°C.

<Example 3> Except for changing the magnesium hydroxide to MAGSEEDS X-6 manufactured by Kamijima Chemical Industry (average particle diameter: 0.81 μm, Ca impurity content: 0.1 atomic %, total impurity content: 0.1 atomic %), it is the same as Example 1. Proceed similarly.

<Example 4> Except for changing the magnesium hydroxide to MAGSTAR #5 manufactured by TATEHO Industrial Co., Ltd. (average particle diameter: 0.99 μm, impurity content: 0.28 atomic %, total impurity content: 0.7 atomic %), the same conditions as in the Examples are used. 1 Proceed in the same way.

<Example 5> The same procedure as in Example 1 was performed except that the alumina particles were changed to DAW-03 (spherical, average particle diameter: 4.9 μm) manufactured by Denka Co., Ltd.

<Example 6> The same procedure as in Example 1 was performed except that the alumina particles were changed to DAW-01 (spherical shape, average particle diameter: 1.9 μm) manufactured by Denka Co., Ltd.

＜Comparative example 1＞ Using an Absolute Mill (manufactured by Osaka Chemical Co., Ltd.), 70 g of alumina particles (manufactured by DENKA Co., Ltd., DAW-05, spherical, average particle diameter 6.4 μm) were mixed with magnesium oxide (Kyowa Chemical Industry Co., Ltd. A mixture was obtained by mixing 27.67 g of Kyowa Mag MF-150 manufactured by the company (average particle diameter 0.71 μm, Ca impurity content 0.64 atomic %, total impurity content 1.7 atomic %). The obtained mixture was put into a crucible, heated to 1300°C using a ceramic electric furnace at 5°C/min, and calcined while maintaining at 1300°C for 10 hours. Then, after cooling to room temperature at 5° C./min, the crucible was taken out, and about 90 g of white powder was obtained.

＜Comparative example 2＞ The same procedure as Comparative Example 1 was performed except that the calcination temperature was changed to 1400°C.

＜Comparative Example 3＞ The same as Comparative Example 1 except that the magnesium hydroxide was changed to MAGSTAR #20 manufactured by Kamijima Chemical Industry (average particle diameter 4 μm, Ca impurity content 0.29 atomic %, total impurity content 0.29 atomic %). carried out.

[Evaluation method] The obtained spinel particles were measured and evaluated according to the following method.

(Measurement of dielectric properties) The spinel particles obtained in the Examples and Comparative Examples were used as test pieces and filled into the cavity resonator CP-001-PW of EM Laboratories. The analysis was performed using the Keysight Network Analyzer P9373A. Measure and determine the dielectric constant/dielectric loss tangent at 1 GHz.

(average particle size) Take a small amount of the spinel particle powder obtained in the Examples and Comparative Examples into a beaker, add 50 mL of 0.5% sodium hexametaphosphate aqueous solution, and then use an ultrasonic homogenizer Sonifier 450D (manufactured by BRANSON) was dispersed for two minutes to prepare a sample for measurement. The volume accumulation standard D50 of this measurement sample was measured using a laser diffraction and scattering particle size distribution measuring device MT3300EXII (manufactured by Microtrac Bell Co., Ltd.).

(Analysis of the amount of elements contained in spinel particles) Composition analysis was performed using a fluorescence X-ray analyzer Supermini 200 (manufactured by Rigaku Co., Ltd.) and using a prepared sample of approximately 5 g. Using the XRF analysis results, for elements other than oxygen, the amount of impurities is calculated based on the molar ratio (number of atoms). That is, let the impurity amount (atomic %) = (number of atoms other than Al and Mg)/(number of atoms of Al + number of atoms of Mg) × 100. Regarding the ratio of Al to Mg, the ratio of the number of atoms is obtained using the same method. Similarly, Ca is set to Ca impurity amount (atomic %) = (number of atoms of Ca)/(number of atoms of Al + number of atoms of Mg) × 100.

The crystallographic phase was measured using Rigaku's X-ray diffraction device Ultima IV (40 kv, 40 mA, CuKα ray). The spinel particles of the Examples and Comparative Examples have MgAl ₂ O ₄ with a spinel type crystal structure, and no other impurity phases were confirmed.

The results of each evaluation are shown in Table 1. "N.D." is the abbreviation of not detected, which means not detected.

[Table 1] particle shape average particle size Total impurity amount Ca impurity amount Dielectric constant Dielectric loss tangent D50 μm atom% atom% Example 1 spherical 9.1 0.07 ND 8.4 9.5×10 ^-4 Example 2 spherical 9.2 0.11 ND 8.8 3.7×10 ^-4 Example 3 spherical 9.2 0.08 ND 8.9 9.1× ^10-4 Example 4 spherical 9.5 0.09 ND 8.7 9.3×10 ^-4 Example 5 spherical 6.2 0.08 ND 9.1 7.0× ^10-4 Example 6 spherical 3.2 0.10 ND 8.9 9.8× ^10-4 Comparative example 1 spherical 9.2 0.27 0.02 8.9 15× ^10-4 Comparative example 2 spherical 9.3 0.30 0.02 8.5 11× ^10-4 Comparative example 3 Amorphous 9.4 0.60 0.30 9.0 12× ^10-4

From Comparative Example 3, it can be seen that when a magnesium-based compound with a large particle size is used, the mechanism of diffusion of the magnesium source into aluminum breaks down and becomes amorphous, so it is necessary to use a fine-particle magnesium-based compound.

(Preparation of Resin Composition) <Example 7> 30.7 g of DIC-PPS LR100G (X-1, polyphenylene sulfide resin manufactured by DIC Co., Ltd. as a thermoplastic resin, density 1.35 g/cm ³ ), 69.3 g of the spinel particles obtained in Example 1 were uniformly dry-mixed, and then mixed with a resin melting and kneading device Labo Plastomill at a kneading temperature of 300°C and a rotation speed of 80 rpm. The melt-kneading process is performed under the conditions to obtain a polyphenylene sulfide resin composition with a content of the particles of 40% by volume. The filler content (volume %) in the resin composition is calculated based on the density of the thermoplastic resin and the density of the thermally conductive filler.

(Measurement method of thermal conductivity of thermoplastic resin composition) The obtained resin composition was injection molded using a desktop injection molding machine (manufactured by Xplore, Injection Molding IM 12) at a cylinder temperature of 320°C and a mold temperature of 140°C to produce a diameter 10 mm, and a test piece with a thickness of 0.2 mm. The thermal conductivity at 25°C was measured using a thermal conductivity measuring device (LFA 467 HyperFlash, manufactured by NETZSCH).

(Example 8 to Example 9, Comparative Example 4) A polyphenylene sulfide resin composition with a filler content of 40% by volume was prepared in the same manner as in Example 7, and the thermal conductivity was measured. Furthermore, the fillers used are shown in Table 2. In addition, in Comparative Example 4, DAW-05 (manufactured by Denka Co., Ltd., spherical alumina) was used as the filler.

[Table 2] Filling type Thermal conductivity (W/m·K) Example 7 Example 1 0.92 Example 8 Example 2 0.93 Example 9 Example 3 0.95 Comparative example 4 DAW-05 0.76

The resin composition containing the spinel particles of this embodiment generally has a higher thermal conductivity than a resin composition containing alumina with high thermal conductivity. It can be said that it achieves both high thermal conductivity and low dielectric loss. The angle is tangent to the two spinel particles.

without

Figure 1 is an SEM image of the spinel particles of Example 1. Figure 2 is an SEM image of the spinel particles of Example 3. Figure 3 is an SEM image of the spinel particles of Example 4. FIG. 4 is an SEM image of the spinel particles of Comparative Example 3.

Claims (9)

A kind of spinel particle, containing at least magnesium atoms, aluminum atoms and oxygen atoms, in the spinel particle, The amount of atoms other than the above atoms is less than 0.27 atomic %. A kind of spinel particle, containing at least magnesium atoms, aluminum atoms and oxygen atoms, in the spinel particle, The number of calcium atoms is less than 0.02 atomic % relative to the sum of the numbers of magnesium atoms and aluminum atoms. The spinel particles according to claim 1 or 2, wherein the average particle diameter is 75 μm or less. The spinel particle according to Claim 1 or 2, wherein the dielectric loss tangent at 1 GHz is less than 1.0×10 ^-3 . A resin composition comprising the spinel particles described in claim 1 or 2 and resin. A molded article of the resin composition according to claim 5. A method for producing spinel particles, in which an aluminum-based compound and a magnesium-based compound are mixed and calcined. In the method for producing spinel particles, The magnesium compound is fine particles with an average particle diameter of less than 4 μm, The amount of impurities contained in the magnesium-based compound is less than 1.0 atomic %. A method for producing spinel particles, in which an aluminum-based compound and a magnesium-based compound are mixed and calcined. In the method for producing spinel particles, The magnesium compound is fine particles with an average particle diameter of less than 4 μm, The calcium atomic weight contained in the magnesium-based compound is 0.6 atomic % or less. The manufacturing method according to claim 7 or 8, wherein the shape of the aluminum-based compound is spherical or spherical.