Surface-treated forsterite particle and method for manufacturing surface-treated forsterite particle

Abstract

To provide a surface-treated forsterite particle with excellent dielectric properties and a method for manufacturing a surface-treated forsterite particle.SOLUTION: The surface of a forsterite particle is coated with a monofunctional silane and / or silazane (A) to create a surface-treated forsterite particle.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to surface-treated forsterite particles and a method for producing the surface-treated forsterite particles. [Background technology]

[0002] Forsterite has excellent strength and is used as a thin-walled insulating material. It also has high insulation resistance and is widely used as an electrical insulating material. Furthermore, due to its large thermal expansion coefficient, it is used in places where adhesion to metals is important, such as insulating parts for vacuum tubes and base materials for metal film resistors.

[0003] Forsterite also has a dielectric constant of 6.5, a small dielectric tangent (tan δ) and low microwave loss, making it useful as a high-frequency insulating material. It is an inorganic material that is expected to be used in the future as 5G becomes more widespread.

[0004] Patent Document 1 discloses a method for producing forsterite microparticles, in which a solution containing a water-soluble magnesium salt and colloidal silica in a molar ratio of magnesium atoms to silicon atoms (Mg / Si) of 2 is sprayed into an atmosphere at a temperature of 50°C or higher and lower than 300°C, dried, and then fired in air at a temperature of 800 to 1000°C to obtain forsterite microparticles with a primary particle size in the range of 1 to 200 nm as determined by observation with an electron microscope.

[0005] Patent Document 2 discloses silane-treated forsterite fine particles, and the production method thereof includes: (a) step: 5 to 100 m 2The method for producing an organic solvent dispersion of silane-treated forsterite microparticles includes the steps of: (a) wet-grinding forsterite microparticles having a specific surface area of ​​100 nm to 200 nm in a dispersion medium containing an organic solvent using a bead mill to obtain an organic solvent dispersion; and (b) adding methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, methacryloxypropyltrimethoxysilane and / or hydrolysates thereof to the organic solvent dispersion obtained in step (a) so that the mass ratio of the organosilicon compound to the forsterite microparticles (organosilicon compound / forsterite microparticles) is 0.01 to 0.50, thereby bonding methyltrimethoxysilyl groups, phenyltrimethoxysilyl groups, methyltriethoxysilyl groups, and methacryloxypropyltrimethoxysilyl groups to the surfaces of the forsterite microparticles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-222517 A [Patent Document 2] JP 2020-100561 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the forsterite particles in Patent Document 1 are nano-sized, severely aggregated, and have a wide particle size distribution. Therefore, when actually using the forsterite particles, it is necessary to deflocculate the particles in some way, which is not practical.

[0008] Furthermore, Patent Document 2 discloses a method for improving dispersibility by performing a silane treatment, but the resulting silane-treated forsterite particles have poor dielectric properties, and there is still room for improvement.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide surface-treated forsterite particles having excellent dielectric properties, and a method for producing the surface-treated forsterite particles. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above problems, the inventors discovered that forsterite particles with excellent dielectric properties can be produced by coating with a monofunctional silane or a monofunctional silazane, and thus completed the present invention. That is, the present invention has the following aspects.

[0011] (1) Surface-treated forsterite particles, the surfaces of which are coated with a monofunctional silane and / or silazane (A). (2) The surface-treated forsterite particles according to the above (1), wherein the average primary particle diameter of the forsterite particles is 0.05 to 30.0 μm. (3) The surface-treated forsterite particles according to (1) or (2) above, wherein the monofunctional silane and / or silazane (A) is one selected from the group consisting of trimethylmethoxysilane, trimethylethoxysilane, trimethylsilanol, triphenylmethoxysilane, hexamethyldisilazane, hexaethyldisilazane, bis(ethyldimethyl)silylamine, and bis(phenyldimethyl)silylamine. (4) A resin dispersion containing the surface-treated forsterite particles according to any one of (1) to (3) above. (5) A method for producing surface-treated forsterite particles, comprising: (I) a step of calcining a magnesium compound and silicon or a silicon compound at 900 to 1500°C; and (II) a step of heating the forsterite particles obtained in step (I) in the presence of a monofunctional silane and / or silazane (A). Effect of the Invention

[0012] According to the present invention, it is possible to provide surface-treated forsterite particles having excellent dielectric properties, and a method for producing the surface-treated forsterite particles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the surface-treated forsterite particles and the method for producing the surface-treated forsterite particles of the present invention will be described.

[0014] <Surface-treated forsterite particles> The forsterite particles of the embodiment are coated with a monofunctional silane and / or silazane (A). The surface-treated forsterite particles of the embodiment are suppressed in terms of moisture adsorption and have excellent dielectric properties.

[0015] Furthermore, the surface-treated forsterite particles according to the embodiment have little or no aggregation, and can have excellent handleability.

[0016] The silanol group concentration on the particle surface of the surface-treated forsterite particles according to the embodiment is 0.0001 to 0.01 mmol / m 2 It is preferable that the concentration is 0.0005 to 0.005 mmol / m 2 More preferably, it is 0.001 to 0.003 mmol / m 2 When the silanol group concentration on the particle surface is within the above range, it is believed that adsorption of moisture over time is suppressed, which is preferable since it contributes to improving the dielectric properties.

[0017] The silanol group concentration can be measured, for example, by a lithium aluminum hydride method, which is a method in which the surface-treated forsterite particles are dried under specified conditions, then reacted with lithium aluminum hydride in a solvent (e.g., 1,4-dioxane, etc.), and the amount of hydrogen generated is measured to quantify the silanol group concentration.

[0018] [Forsterite particles] The surface-treated forsterite particles according to the embodiment include forsterite particles having a composition of Mg2SiO4.

[0019] The forsterite particles preferably contain 65 mass % or more of Mg2SiO4, preferably 65 to 99.95 mass %, more preferably 70 to 99.5 mass %, and even more preferably 75 to 99 mass %, relative to 100 mass % of the forsterite particles.

[0020] The magnesium content in the forsterite particles can be measured by XRF analysis. The magnesium content in the forsterite particles of the embodiment is preferably 30 to 80 mass%, more preferably 35 to 70 mass%, and even more preferably 40 to 66 mass%, in terms of MgO content (Mg1) relative to 100 mass% of the forsterite particles, as determined by XRF analysis of the forsterite particles.

[0021] The silicon content in the forsterite particles can be measured by XRF analysis. The silicon content in the forsterite particles of the embodiment is preferably 10 to 60 mass%, more preferably 15 to 50 mass%, and even more preferably 20 to 45 mass%, in terms of SiO2 content (Si1) relative to 100 mass% of the forsterite particles, as determined by XRF analysis of the forsterite particles.

[0022] For the above-mentioned XRF analysis, an X-ray fluorescence analyzer (for example, Primus IV manufactured by Rigaku Corporation) can be used.

[0023] The content (Mg1) calculated as MgO refers to the value calculated from the amount of MgO calculated by converting the magnesium content determined by XRF analysis of forsterite particles using a calibration curve calculated as MgO.

[0024] The content (Si1) in terms of SiO2 refers to the value obtained from the amount of SiO2 calculated by converting the silicon content determined by XRF analysis of forsterite grains using a calibration curve in terms of SiO2.

[0025] The magnesium content in the surface layer of the forsterite particle can be measured by XPS (X-ray photoelectron spectroscopy) surface analysis. The magnesium content in the surface layer of the forsterite particle of the embodiment is preferably 1 to 70 mass%, more preferably 3 to 60 mass%, and even more preferably 5 to 50 mass%, in terms of MgO content (Mg2) relative to 100 mass% of the surface layer of the forsterite particle, as determined by XPS surface analysis of the forsterite particle.

[0026] The silicon content in the surface layer of the forsterite particle can be measured by XPS (X-ray photoelectron spectroscopy) surface analysis. The silicon content in the surface layer of the forsterite particle of the embodiment is preferably 1 to 70 mass%, more preferably 3 to 60 mass%, and even more preferably 5 to 50 mass%, in terms of SiO2 content (Si2) relative to 100 mass% of the surface layer of the forsterite particle, as determined by XPS surface analysis of the forsterite particle.

[0027] For the above-mentioned XPS analysis, a scanning X-ray photoelectron spectrometer (for example, QUANTERA SXM manufactured by ULVAC-PHI, Inc.) can be used.

[0028] The above content (Mg2) refers to the value obtained by performing XPS surface analysis of forsterite particles using X-ray photoelectron spectroscopy (XPS) to obtain the abundance ratio (atom%) of each element, and converting the magnesium content into oxide to obtain the MgO content relative to 100% by mass of the surface layer of the forsterite particle.

[0029] The above content (Si2) refers to the value obtained by performing XPS surface analysis of the forsterite particles using X-ray photoelectron spectroscopy (XPS) to obtain the abundance ratio (atom%) of each element, and converting the silicon content into oxide to obtain the SiO2 content relative to 100% by mass of the surface layer of the forsterite particle.

[0030] In this specification, the term "surface layer" refers to a region within 10 nm from the surface of a forsterite particle. This distance corresponds to the detection depth of the XPS used in the measurements in the examples.

[0031] The forsterite grains may be regarded as an aggregate of forsterite grains, and the above-mentioned magnesium content and silicon content values ​​can be values ​​determined by using the aggregate as a sample.

[0032] The forsterite particles may further contain molybdenum, lithium, potassium, or sodium. These elements can be contained within a range that does not impair the effects of the present invention.

[0033] For example, when molybdenum is contained, the molybdenum content in the forsterite particles is preferably 0.05 mass% or more, more preferably 0.05 to 35 mass%, more preferably 0.08 to 30 mass%, and even more preferably 0.09 to 25 mass%, in terms of MoO3 content (Mo1) relative to 100 mass% of the forsterite particles, as determined by XRF analysis of the forsterite particles.

[0034] In this case, the upper and lower limit values ​​of the content (Mg1), content (S1), and content (Mo1) in the forsterite grains can be freely combined. In addition, the values ​​of the content (Mg1), content (Si1), and content (Mo1) can also be freely combined.

[0035] The content (Mo1) in terms of MoO3 refers to the value obtained from the amount of MoO3 converted by using a calibration curve in terms of MoO3 to convert the molybdenum content determined by XRF analysis of forsterite grains.

[0036] When molybdenum is contained, the molybdenum content in the surface layer of the forsterite particle is determined by XPS surface analysis of the forsterite particle, and is preferably a content (Mo2) in terms of MoO3 relative to 100 mass% of the surface layer of the forsterite particle of 0.05 mass% or more, preferably 0.05 to 25 mass%, more preferably 0.08 to 20 mass%, and even more preferably 0.1 to 15 mass%.

[0037] The above content (Mo2) refers to the value obtained by performing XPS surface analysis of forsterite particles using X-ray photoelectron spectroscopy (XPS) to obtain the abundance ratio (atom%) of each element, and converting the molybdenum content into an oxide to obtain the MoO3 content relative to 100% by mass of the surface layer of the forsterite particle.

[0038] As the forsterite particles, commercially available forsterite may be used, forsterite may be produced from a magnesium-containing raw material and a silicon-containing raw material by a known method, or forsterite may be produced by a method described later. Among them, forsterite obtained by the method described later is preferable because it can be controlled to a desired particle size and shape.

[0039] The average particle size of the primary particles of the forsterite particles is preferably 0.05 to 30.0 μm, more preferably 0.08 to 20.0 μm, and particularly preferably 0.1 to 10.0 μm. When the average particle size of the primary particles is within the above range, aggregation of the particles is suppressed when the particles are used as a low dielectric material to prepare a dielectric film, and a film with a desired film thickness is easily obtained, which is preferable.

[0040] The average particle size of the primary particles of the forsterite particles is calculated as a converted particle size based on the specific surface area described below, assuming that the particles are spherical. The following conversion formula is used. Primary particle diameter Dsa[nm]=6000 / (density[g / cm 3 ] × specific surface area [m 2 / g])

[0041] The median diameter D of forsterite particles calculated by the laser diffraction / scattering method 50 The thickness may be 0.1 to 50 μm, 0.2 to 30 μm, 0.3 to 10 μm, or 0.4 to 5 μm.

[0042] The median diameter D of the forsterite grain sample calculated by the laser diffraction / scattering method 50 can be calculated as the particle size at which the volume cumulative percentage is 50% in the particle size distribution measured in a dry state using a laser diffraction particle size distribution analyzer.

[0043] The specific surface area of ​​forsterite particles, as determined by the BET method, is 0.1 to 40 m 2 / g, and may be 0.13 to 25m 2 / g, and may be 0.2 to 20m 2 / g.

[0044] The specific surface area is measured using a specific surface area meter (e.g., BELSORP-mini, manufactured by Microtrack-Bell Corporation), and the surface area per 1 g of the sample measured from the amount of nitrogen gas adsorbed by the BET method (Brunauer-Emmett-Teller method) is defined as the specific surface area (m 2 / g).

[0045] [Monofunctional silanes, monofunctional silazanes] The surface-treated forsterite particles of the embodiment are characterized by being coated with a monofunctional silane and / or silazane (A). By using the monofunctional silane and / or silazane (A), it is preferable to suppress the unbonded modifier from remaining on the surface of the surface-treated forsterite particles.

[0046] The monofunctional silane is not particularly limited, and examples thereof include ethyl dimethyl methoxy silane, n-propyl dimethyl methoxy silane, isopropyl dimethyl methoxy silane, n-butyl dimethyl methoxy silane, n-hexyl dimethyl methoxy silane, n-octyl dimethyl methoxy silane, trimethyl methoxy silane, trimethyl ethoxy silane, phenyl dimethyl methoxy silane, vinyl dimethyl methoxy silane, triethyl methoxy silane, triethyl ethoxy silane, etc. Trimethyl methoxy silane, vinyl dimethyl methoxy silane, phenyl dimethyl methoxy silane, and trimethyl ethoxy silane are more preferred because of their excellent hydrolysis rate and condensation rate, and trimethyl methoxy silane and trimethyl ethoxy silane are even more preferred because the boiling point of the hydrolysis condensate is low and easy to remove from the system.

[0047] The monofunctional silazane is not particularly limited, but examples thereof include hexamethyldisilazane, bis(ethyldimethyl)silylamine, bis(vinyldimethyl)silylamine, and bis(phenyldimethyl)silylamine. Hexamethyldisilazane is more preferable from the viewpoints of excellent hydrolysis rate and condensation rate, and the boiling point of the hydrolysis condensate is low and easy to remove from the system.

[0048] In the present invention, the surface treatment may use one type selected from monofunctional silanes or monofunctional silazanes, or two or more types may be used in combination. When two or more types are used in combination, two or more types of monofunctional silanes may be used, or two or more types of monofunctional silazanes may be used, or one or more types of each of monofunctional silanes and monofunctional silazanes may be used in combination.

[0049] <Method for manufacturing surface-treated forsterite particles> The surface-treated forsterite particles may be prepared by mixing commercially available forsterite particles with the monofunctional silane or the monofunctional silazane and heating the mixture to form a coating treatment, or by separately producing forsterite particles, mixing the monofunctional silane and / or the silazane (A) and heating the coating treatment.

[0050] When forsterite particles are produced separately, it is preferable that the process includes (I) a step of calcining a magnesium compound and silicon or a silicon compound at 900 to 1500°C, and (II) a step of heating the forsterite particles obtained in step (I) in the presence of a monofunctional silane or a monofunctional silazane.

[0051] (Process (I)) Step (I) is a step of firing the magnesium compound and silicon or a silicon compound at 900 to 1500° C. It is preferable to mix the magnesium compound and silicon or a silicon compound prior to firing.

[0052] (Magnesium compounds) The type of the magnesium compound is not particularly limited. For example, the magnesium compound may be magnesium hydroxide, magnesium oxide, magnesium carbonate, magnesium silicate, magnesium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, etc., and magnesium hydroxide or magnesium carbonate is preferred from the viewpoint of ease of reaction, and magnesium hydroxide is more preferred from the viewpoint of the generated gas being water, which is easy to handle.

[0053] Since the shape of the forsterite particles after sintering hardly reflects the shape of the raw magnesium compound, for example, spherical, amorphous, aspected structures (wires, fibers, ribbons, tubes, etc.), sheets, etc. can be suitably used as the magnesium compound.

[0054] (Silicon or silicon compounds) The type of silicon or silicon compound is not particularly limited, and any known silicon compound, including silicon atoms, can be used.Specific examples of these include artificially synthesized silicon compounds such as silica (SiO2), magnesium silicate, silicomolybdic acid, metal silicon (silicon atom), organic silane compounds, silicone resins, silica particles, silica gel, mesoporous silica, SiC, and mullite; and natural silicon compounds such as biosilica.

[0055] The shape of silicon or a silicon compound containing elemental silicon is not particularly limited, and for example, a sphere, an amorphous shape, an aspected structure (wire, fiber, ribbon, tube, etc.), a sheet, etc. can be suitably used.

[0056] (Other compounds) In the production method of the embodiment, a molybdenum compound, a sodium compound, or a potassium compound may be further mixed, and these may be used alone or in combination.

[0057] (Molybdenum Compounds) Examples of the molybdenum compound include molybdenum oxide, molybdic acid, molybdenum sulfide, silicomolybdic acid, magnesium molybdate, and molybdate compounds, with molybdenum oxide and molybdate compounds being preferred.

[0058] The molybdenum oxide includes molybdenum dioxide (MoO2), molybdenum trioxide (MoO3), etc., with molybdenum trioxide being preferred due to its ease of availability.

[0059] The molybdate compound is MoO4 2- , Mo2O7 2- , Mo3O 10 2- , Mo4O 13 2- , Mo5O 16 2- , Mo6O 19 2- , Mo7O 24 6- , Mo8O 26 4-The molybdenum oxoanion may be, but is not limited to, a salt compound of the molybdenum oxoanion such as those mentioned above. The molybdenum oxoanion may be an alkali metal salt, an alkaline earth metal salt, or an ammonium salt.

[0060] The molybdate compound is preferably an alkali metal salt of a molybdenum oxoanion, more preferably lithium molybdate, potassium molybdate or sodium molybdate, even more preferably potassium molybdate or sodium molybdate, and particularly preferably sodium molybdate.

[0061] The molybdate compound may be a hydrate.

[0062] The molybdenum compound is preferably at least one compound selected from the group consisting of molybdenum trioxide, lithium molybdate, potassium molybdate, and sodium molybdate, more preferably at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate, and further preferably molybdenum trioxide and / or sodium molybdate.

[0063] By using a molybdate compound, the molybdenum content of the produced forsterite particles tends to be reduced, which is preferable from the viewpoint of increasing the crystallinity of the forsterite. In addition, the particle size (median diameter D 50 ) can be controlled.

[0064] The molybdate compound is AMo x O 3x+1 where A is preferably lithium, sodium or potassium. As described above, the particle size of the obtained forsterite particles is appropriately controlled by the type of counter cation represented by A and / or the amount of molybdic acid in one molecule of the molybdate compound. For example, the smaller the period of the periodic table is for the counter cation, the larger the particle size tends to be. This is presumably because, in the same group, the smaller the period is for the element, the less basic it tends to be, which weakens the acid-base interaction between the molybdate ion, which is an acid, and the counter cation, resulting in more free MoO3 components. Therefore, although A is not particularly limited, lithium is preferred because it can provide a particularly large particle size, followed by sodium and potassium, which provide the largest particle size in that order. Also, A2Mo x O 3x+1 In the compound represented by the formula, the larger the value of x, the larger the particle size tends to be. This is presumably because the larger the value of x, the less likely it is to be bound by the counter cation, and the more MoO3 components can participate in the reaction. Therefore, although x is not particularly limited, when x=3, a particularly large particle size can be obtained, followed by x=2 and x=1, which are preferred in that order. The effect of such a molybdate compound can be applied not only to forsterite particles but also to other single oxides and double oxides.

[0065] (Sodium compounds) The sodium compound is not particularly limited, but examples thereof include sodium carbonate, sodium molybdate, sodium oxide, sodium sulfate, sodium hydroxide, sodium nitrate, sodium chloride, metallic sodium, etc. Among these, it is preferable to use sodium carbonate, sodium molybdate, sodium oxide, and sodium sulfate from the viewpoints of industrial ease of availability and ease of handling.

[0066] The above-mentioned sodium compounds may be used alone or in combination of two or more kinds.

[0067] As described above, sodium molybdate contains molybdenum and can therefore function as the molybdenum compound described above.

[0068] (Potassium compounds) The potassium compound is not particularly limited, but includes potassium chloride, potassium chlorite, potassium chlorate, potassium sulfate, potassium hydrogen sulfate, potassium sulfite, potassium hydrogen sulfite, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium acetate, potassium oxide, potassium bromide, potassium bromate, potassium hydroxide, potassium silicate, potassium phosphate, potassium hydrogen phosphate, potassium sulfide, potassium hydrogen sulfide, potassium molybdate, potassium tungstate, etc. In this case, the potassium compound includes isomers, as in the case of molybdenum compounds. Among these, it is preferable to use potassium carbonate, potassium hydrogen carbonate, potassium oxide, potassium hydroxide, potassium chloride, potassium sulfate, and potassium molybdate, and it is more preferable to use potassium carbonate, potassium hydrogen carbonate, potassium chloride, potassium sulfate, and potassium molybdate.

[0069] The potassium compounds described above may be used alone or in combination of two or more kinds.

[0070] Use of a sodium compound and / or a potassium compound is preferable because it makes it easy to adjust the particle size of the forsterite particles produced and makes it easy to produce forsterite particles with little or no aggregation.

[0071] Here, at least a part of the molybdenum compound and the sodium compound may be replaced with a compound containing molybdenum and sodium, such as sodium molybdate, and at least a part of the molybdenum compound and the potassium compound may be replaced with a compound containing molybdenum and potassium, such as potassium molybdate.

[0072] The compound containing molybdenum and sodium can be produced, for example, during the firing process using a molybdenum compound and a sodium compound, which are cheaper and more readily available, as raw materials. Here, the use of a molybdenum compound and a sodium compound as fluxing agents and the use of a compound containing molybdenum and sodium as fluxing agents are both considered to be the use of a molybdenum compound and a sodium compound as fluxing agents, i.e., in the presence of a molybdenum compound and a sodium compound.

[0073] A compound containing molybdenum and potassium suitable as a fluxing agent can be produced, for example, in the firing process using a molybdenum compound and a potassium compound, which are cheaper and more readily available, as raw materials. Here, the use of a molybdenum compound and a potassium compound as fluxing agents and the use of a compound containing molybdenum and potassium as fluxing agents are both considered to be the use of a molybdenum compound and a potassium compound as fluxing agents, i.e., in the presence of a molybdenum compound and a potassium compound.

[0074] In addition, sodium molybdate (Na2Mo n O 3n+1 , n=1 to 3) contains sodium and can therefore function as a sodium compound, which will be described later.

[0075] In addition, potassium molybdate (K2Mo n O 3n+1 , n=1 to 3) contains potassium and can therefore also function as a potassium compound, which will be described later.

[0076] In the method for producing forsterite particles of this embodiment, the molar ratio of magnesium to silicon (Mg / Si) in the raw material, for example in the mixture, is basically 2, and since any excess MgO that may be produced can be easily removed, the Mg / Si may be 2 or more, may be 2.05 to 2.5, or may be 2.1 to 2.3.

[0077] When the mixture further contains molybdenum, the molar ratio (molybdenum / (magnesium+silicon)) of the molybdenum atoms in the molybdenum compound to the magnesium and silicon atoms in the magnesium compound and silicon compound in the mixture is preferably 0.002 or more, more preferably 0.005 or more, even more preferably 0.01 or more, and particularly preferably 0.02 or more.

[0078] In addition, the upper limit of the molar ratio of molybdenum atoms in the molybdenum compound to magnesium and silicon atoms in the magnesium compound and silicon compound in the mixture may be determined appropriately. From the viewpoint of reducing the amount of molybdenum compound used and improving production efficiency, for example, the molar ratio (molybdenum / (magnesium+silicon)) may be 1.0 or less, 0.7 or less, 0.5 or less, or 0.3 or less.

[0079] An example of the numerical range of the molar ratio (molybdenum / (magnesium+silicon)) in the mixture is, for example, the value of molybdenum / (magnesium+silicon) may be 0.005 to 1.0, 0.01 to 0.7, 0.015 to 0.5, or 0.02 to 0.3.

[0080] It should be noted that the more the amount of molybdenum used relative to magnesium and silicon, and the more molybdenum atoms contained per molecule of the molybdate used, the larger the particle size of the forsterite particles that can be obtained tends to be.

[0081] In an embodiment, the mixture is fired to obtain forsterite particles. The state of the magnesium compound, silicon or silicon compound, and molybdenum compound during firing is not particularly limited, and the molybdenum compound may be present in the same space where it can act on the magnesium compound and silicon or silicon compound. Specifically, the molybdenum compound powder, the magnesium compound powder, and the silicon or silicon compound powder may be simply mixed together, mechanically mixed using a grinder, or mixed using a mortar, or may be mixed in a dry or wet state.

[0082] The firing temperature is not particularly limited and is appropriately determined in consideration of the particle size, shape, etc. of the target forsterite particles. The firing temperature may be 1400°C or higher, 1300°C or higher, 1200°C or higher, 1100°C or higher, or 1000°C or higher.

[0083] The higher the firing temperature, the more easily the particle shape is controlled and the larger the particle size of the forsterite particles is obtained. From the viewpoint of efficiently producing such forsterite particles, the firing temperature is preferably 850° C. or higher, more preferably 900° C. or higher, even more preferably 950° C. or higher, and particularly preferably 1000° C. or higher.

[0084] Furthermore, according to the method for producing forsterite particles mixed with a molybdenum compound, idiomorphous forsterite particles can be formed regardless of the shape of the precursor even at a firing temperature of 1600°C or less, which is much lower than the melting point of forsterite. From this viewpoint, the firing temperature is preferably 1500°C or less, more preferably 1400°C or less, and even more preferably 1300°C or less.

[0085] In the firing step, the numerical range of the firing temperature at which the magnesium compound and silicon or the silicon compound are fired may be, for example, 900 to 1500°C, 950 to 1400°C, 950 to 1300°C, or 950 to 1200°C.

[0086] From the viewpoint of production efficiency, the temperature rise rate may be 20 to 600° C. / h, 40 to 500° C. / h, or 80 to 400° C. / h.

[0087] Regarding the firing time, the time required to raise the temperature to a predetermined firing temperature is preferably within the range of 15 minutes to 10 hours. The holding time at the firing temperature can be 5 minutes or more, and is preferably within the range of 5 minutes to 1000 hours, and more preferably within the range of 1 to 30 hours. In order to efficiently form forsterite particles, it is more preferable to hold the firing temperature for 2 hours or more, and particularly preferably to hold the firing temperature for 2 to 24 hours.

[0088] The firing atmosphere is not particularly limited as long as the effects of the present invention can be obtained. For example, an oxygen-containing atmosphere such as air or oxygen, or an inert atmosphere such as nitrogen, argon, or carbon dioxide is preferable, and an air atmosphere is more preferable in terms of cost.

[0089] The calcination apparatus is not necessarily limited, and a so-called calcination furnace can be used. If a molybdenum compound is mixed, the calcination furnace is preferably made of a material that does not react with the sublimated molybdenum oxide, and it is preferable to use a highly airtight calcination furnace so that the molybdenum oxide is efficiently utilized.

[0090] The forsterite particles obtained by firing are preferably cooled.

[0091] The cooling rate is not particularly limited, but is preferably 1 to 1000°C / hour, more preferably 5 to 500°C / hour, and even more preferably 50 to 100°C / hour. A cooling rate of 1°C / hour or more is preferable because the manufacturing time can be shortened. On the other hand, a cooling rate of 1000°C / hour or less is preferable because the firing container is less likely to crack due to heat shock and can be used for a long time.

[0092] The cooling method is not particularly limited, and may be natural cooling or a cooling device may be used.

[0093] When a molybdenum compound is mixed, a molybdenum removal treatment may be carried out. Methods for removing molybdenum include washing and high-temperature treatment, which may be performed in combination.

[0094] Molybdenum may adhere to the surface of the forsterite grains, and can be removed, for example, by washing with water, an aqueous ammonia solution, an aqueous sodium hydroxide solution, or the like.

[0095] As a method for high-temperature treatment, a method in which the temperature is raised to the sublimation point or boiling point of the molybdenum compound or higher can be mentioned.

[0096] In the sintered product obtained through the sintering step, the forsterite particles may aggregate and may not satisfy the suitable particle size range for the intended application. Therefore, the forsterite particles may be pulverized as necessary to satisfy the suitable particle size range. The method for pulverizing the fired product is not particularly limited, and any conventionally known pulverizing method such as a ball mill, a jaw crusher, a jet mill, a disk mill, a spectromill, a grinder, or a mixer mill can be used.

[0097] The sintered product containing forsterite particles obtained by the sintering step may be appropriately classified to adjust the particle size range. "Classification" refers to an operation of classifying particles into groups according to their size.

[0098] The classification may be either a wet type or a dry type, but from the viewpoint of productivity, a dry type classification is preferred. Dry classification includes classification using a sieve as well as wind classification, which classifies based on the difference between centrifugal force and fluid drag. From the viewpoint of classification accuracy, wind classification is preferred, and can be carried out using a classifier such as an air current classifier that utilizes the Coanda effect, a swirling air current classifier, a forced vortex centrifugal classifier, or a semi-free vortex centrifugal classifier.

[0099] The above-mentioned pulverization and classification can be carried out at any stage required. Depending on whether or not the pulverization and classification are carried out and the selection of the conditions therefor, for example, the average particle size of the obtained forsterite particles can be adjusted.

[0100] (Step (II)) Step (II) is a step of heating the forsterite particles obtained in step (I) in the presence of a monofunctional silane and / or silazane (A).

[0101] The method of coexistence and heating in step (II) is not particularly limited, but the following methods can be used, for example: a method in which the monofunctional silane and / or silazane (A) is directly mixed with the forsterite particles and heated to surface-modify the forsterite particles, or a method in which the monofunctional silane and / or silazane (A) and the forsterite particles are placed in separate open containers, and these containers are placed in the same closed container and heated to vaporize the monofunctional silane and / or silazane (A) to surface-modify the forsterite particles. EXAMPLES

[0102] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0103] <Evaluation> The powder obtained in each production example was used as a sample powder and the following evaluations were carried out.

[0104] [Crystal structure analysis: XRD (X-ray diffraction) method] The sample powder was filled into a measurement sample holder with a depth of 0.5 mm, which was then set into a wide-angle X-ray diffraction (XRD) device (Ultima IV, manufactured by Rigaku Corporation) and measurements were performed under the following conditions: Cu / Kα radiation, 40 kV / 40 mA, scan speed 2° / min, and scan range 10 to 70°.

[0105] [Measuring the average particle size of forsterite particles] A small amount of the sample powder was placed in a beaker, 50 mL of 0.5% sodium hexametaphosphate aqueous solution was added, and then the powder was dispersed for 2 minutes using an ultrasonic homogenizer, Sonifier 450D (manufactured by Branson Co., Ltd.) to prepare a measurement sample. This measurement sample was measured using a laser diffraction scattering type particle size distribution measuring device MT3300EXII (manufactured by Microtrack Bell Co., Ltd.) to determine the volume cumulative standard D 10 , D 50 , D 90 was measured.

[0106] [Measurement of specific surface area of ​​forsterite particles] The specific surface area of ​​the forsterite particles was measured using a specific surface area meter (Microtrack-Bel, BELSORP-mini), and the surface area per 1 g of sample measured from the amount of nitrogen gas adsorbed by the BET method was defined as the specific surface area (m 2 / g).

[0107] [Measurement of primary particle size of forsterite particles] The average particle size of the primary particles of the forsterite particles was calculated as a converted particle size based on the specific surface area described above, assuming that the particles were spherical. The following conversion formula was used. Primary particle diameter Dsa[nm]=6000 / (density[g / cm 3 ] × specific surface area [m 2 / g])

[0108] The powders obtained in each of the Examples and Comparative Examples were used as sample powders and further evaluated as follows.

[0109] [Evaluation of dielectric properties of surface-treated forsterite particles] The forsterite particles obtained in the examples and comparative examples were used as sample powder and filled into an EM Lab cavity resonator CP-001-PW. Measurements were then performed using a Keysight network analyzer P9373A to measure the relative permittivity (ε') and dielectric loss (ε") at 1 GHz. The dielectric loss tangent was calculated using the following formula. Dielectric tangent = dielectric loss (ε”) / relative dielectric constant (ε') The obtained sample powder was left to stand indoors for one week, and then the same measurements were carried out again to evaluate the dielectric properties over time.

[0110] <Flux manufacturing> [Lithium dimolybdate (Li2Mo2O7)] 173.8 g of lithium monomolybdate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 144.0 g of molybdenum trioxide were mixed in a mortar, and the mixed powder was placed in an alumina sagger and reacted in an electric furnace at 700°C for 5 hours to obtain lithium dimolybdate (flux 1). The heating rate was 5°C / min.

[0111] [Sodium dimolybdate (Na2Mo2O7)] 242.0 g of sodium monomolybdate dihydrate (Kanto Chemical Co., Ltd.) and 144.0 g of molybdenum trioxide were mixed in a mortar, and the mixed powder was placed in an alumina sagger and reacted in an electric furnace at 700°C for 5 hours to obtain sodium dimolybdate (Flux 2). The heating rate was 5°C / min.

[0112] [Lithium trimolybdate (Li2Mo3O 10 )] 173.8 g of lithium monomolybdate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 288.0 g of molybdenum trioxide were mixed in a mortar, and the mixed powder was placed in an alumina sagger and reacted in an electric furnace at 700°C for 5 hours to obtain lithium trimolybdate (flux 3). The heating rate was 5°C / min.

[0113] [Sodium Trimolybdate (Na2Mo3O 10 )] 242.0 g of sodium monomolybdate dihydrate (Kanto Chemical Co., Ltd.) and 288.0 g of molybdenum trioxide were mixed in a mortar, and the mixed powder was placed in an alumina sagger and reacted in an electric furnace at 700°C for 5 hours to obtain sodium trimolybdate (Flux 4). The heating rate was 5°C / min.

[0114] [Potassium trimolybdate (K2Mo3O 10 )] 238.1 g of potassium monomolybdate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 288.0 g of molybdenum trioxide were mixed in a mortar, and the mixed powder was placed in an alumina sagger and reacted in an electric furnace at 700°C for 5 hours to obtain potassium trimolybdate (Flux 5). The heating rate was 5°C / min.

[0115] <Production of forsterite particles> [Production Example 1] 80 g of magnesium oxide (MF30, manufactured by Kyowa Chemical Industry Co., Ltd.), 66 g of silicon oxide (Nipsil VN3, manufactured by Toso Silica Co., Ltd.), and 14.6 g of sodium monomolybdate dihydrate (reagent, manufactured by Kanto Chemical Co., Ltd.) were placed in a plastic bag and mixed by shaking by hand for 5 minutes. The mixture was placed in a crucible and fired in an electric furnace (manufactured by Motoyama Co., Ltd.) at 1100 °C in air for 10 hours. The heating rate was 5 °C / min. After cooling, the mixture was removed from the electric furnace and transferred to a beaker, washed with stirring in 2 L of water, filtered by suction filtration, and washed with water. The mixture was dried in an oven at 120 °C to obtain forsterite fine particles. Only forsterite peaks were detected by XRD measurement of the obtained product. The median diameter was 1.2 μm and the specific surface area was 9.52 m 2 / g, and the primary particle diameter calculated based on the specific surface area was 0.20 μm.

[0116] [Production Example 2] The same production method as in Production Example 1 was used except that the firing temperature was changed to 1200°C.

[0117] [Production Example 3] The same production method as in Production Example 1 was used except that the firing temperature was changed to 1300°C.

[0118] [Production Example 4] This was produced in the same manner as in Production Example 1, except that the amount of sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was changed to 146 g.

[0119] [Production Example 5] The same production method as in Production Example 4 was used except that the firing temperature was changed to 1300°C.

[0120] [Production Example 6] This was produced in the same manner as in Production Example 1, except that sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was changed to lithium trimolybdate (Flux 3).

[0121] [Production Example 7] This was produced in the same manner as in Production Example 1, except that sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was changed to sodium trimolybdate (Flux 4).

[0122] [Production Example 8] This was produced in the same manner as in Production Example 1, except that sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was changed to potassium trimolybdate (Flux 5).

[0123] [Production Example 9] The same manufacturing method as in Manufacturing Example 1 was used, except that the amount of sodium monomolybdate dihydrate (reagent manufactured by Kanto Chemical Co., Ltd.) was 3.65 g, the amount of lithium dimolybdate (Flux 1) was 3.65 g, and the firing temperature was changed to 900°C. XRD measurement of the obtained product showed that only the peak of forsterite was detected. The median diameter was 1.2 μm, and the specific surface area was 8.91 m. 2 / g, and the primary particle diameter calculated based on the specific surface area was 0.21 μm.

[0124] [Production Example 10] This was produced in the same manner as in Production Example 9, except that the amount of sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was changed to 7.30 g, and the amount of lithium dimolybdate (Flux 1) was changed to 7.30 g.

[0125] [Production Example 11] The sintering temperature was changed to 1100°C, and the same method as in Example 9 was used to produce the sintered product. XRD analysis of the product detected only a forsterite peak. The median diameter was 2.8 μm and the specific surface area was 1.10 m. 2 / g, and the primary particle diameter calculated based on the specific surface area was 1.70 μm.

[0126] [Production Example 12] The powder was produced in the same manner as in Production Example 11, except that the amount of sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was changed to 7.30 g, and the amount of lithium dimolybdate (Flux 1) was changed to 7.30 g. When the obtained product was measured by XRD, only the peak of forsterite was detected. The median diameter was 4.0 μm, and the specific surface area was 0.67 m. 2 / g, and the primary particle diameter calculated based on the specific surface area was 2.80 μm.

[0127] [Production Example 13] The flux was produced in the same manner as in Production Example 11, except that lithium dimolybdate (flux 1) was replaced with sodium dimolybdate (flux 2). The resulting flux was measured by XRD and only the peak of forsterite was detected. The median diameter was 1.9 μm and the specific surface area was 2.07 m. 2 / g, and the primary particle diameter calculated based on the specific surface area was 0.90 μm.

[0128] [Production Example 14] 74.7g of nickel oxide (Kanto Chemical Co., Ltd., reagent), 159.7g of iron(III) oxide (Kanto Chemical Co., Ltd., reagent), and 23.44g of sodium monomolybdate dihydrate (Kanto Chemical Co., Ltd., reagent) were placed in a 500cc polypropylene container, followed by 600g of zirconia beads with a diameter of 5mm, and mixed for 60 minutes using a paint shaker. After separating the beads, the mixture was placed in a crucible and fired in an electric furnace (Motoyama Co., Ltd.,) at 1100°C in air for 5 hours. The heating rate was 5°C min. After cooling, the mixture was removed from the electric furnace, transferred to a beaker, and washed with 2L of water by stirring, then filtered by suction filtration and washed with water. The mixture was dried in an oven at 120°C to obtain nickel ferrite (NiFe2O4) fine particles. Only the peak of nickel ferrite was detected by XRD measurement of the obtained product. The median diameter was 1.8μm, and the specific surface area was 1.27m 2 / g, and the primary particle diameter calculated based on the specific surface area was 0.9 μm. .

[0129] [Production Example 15] This was produced in the same manner as in Production Example 14, except that sodium monomolybdate dihydrate (a reagent manufactured by Kanto Chemical Co., Ltd.) was replaced with lithium dimolybdate (Flux 1). XRD measurement of the product showed that only the peak of nickel ferrite was detected. The median diameter was 14.2 μm and the specific surface area was 0.21 m 2 / g, and the primary particle diameter calculated based on the specific surface area was 5.4 μm.

[0130] [Table 1]

[0131] [Table 2]

[0132] In Tables 1 and 2, the total flux addition rate is the value obtained by dividing the total amount of flux by the total amount of MgO and SiO2.

[0133] [Table 3]

[0134] From Examples 6 to 8, the median diameter D 50 It was confirmed that the median diameter D 50 In addition, from Production Examples 1, 7, and 13, the median diameter D 50 Furthermore, it was confirmed from Production Examples 1 and 4 that the median diameter D50 This tendency was also observed in Production Examples 3 and 5. In addition, in Examples 14 and 15, even in metal oxides other than forsterite, the median diameter D 50 It was verified that the value can be adjusted appropriately.

[0135] <Production of surface-treated forsterite particles> [Example 1] 10 g of the particles prepared in Production Example 12 were placed in a 500 cc screw-top plastic container, and then 0.3 g of hexamethyldisilazane (a reagent manufactured by Kanto Chemical Co., Ltd.) was placed in an open 5 cc glass container and placed in the plastic container without spilling. The lid of the plastic container was tightly closed and placed in a 120°C oven to stand for 5 hours, after which the lid of the plastic container was opened and placed in a 120°C oven again for 1 hour to dry, obtaining surface-modified forsterite. The dielectric properties at 1 GHz were then measured using a dielectric constant measuring device (manufactured by EM Lab). The dielectric loss tangent was 3.3×10 -4 The dielectric loss tangent was 3.7×10. -4 There was almost no deterioration in the dielectric properties.

[0136] [Example 2] 10 g of the particles produced in Production Example 1 were placed in a 500 cc screw-top plastic container, and then 0.3 g of hexamethyldisilazane (a reagent manufactured by Kanto Chemical Co., Ltd.) was placed in an open 5 cc glass container and placed in the plastic container without spilling. The lid of the plastic container was tightly closed and placed in a 120°C oven to stand for 5 hours, after which the lid of the plastic container was opened and placed in a 120°C oven again for 1 hour to dry, obtaining surface-modified forsterite. The dielectric properties at 1 GHz were then measured using a dielectric constant measuring device (manufactured by EM Lab). The dielectric loss tangent was 3.5×10 -4 The dielectric loss tangent was 3.8×10. -4 There was almost no deterioration in the dielectric properties.

[0137] [Comparative Example 1] The particles produced in Production Example 12 were dried again overnight in an oven at 120°C, and then their dielectric properties were measured at 1GHz using a dielectric constant measuring device (manufactured by EM Lab). The dielectric loss tangent was 3.8×10 -4 The dielectric loss tangent was 2.4×10. -3 The dielectric properties were deteriorated.

[0138] [Comparative Example 2] The particles produced in Production Example 1 were dried again overnight in an oven at 120°C, and then their dielectric properties were measured at 1GHz using a dielectric constant measuring device (manufactured by EM Lab). The dielectric loss tangent was 4.1×10 -4 The dielectric loss tangent was 4.2×10 -3 The dielectric properties were deteriorated.

[0139] [Table 4]

Claims

1. Surface-treated forsterite particles, the surfaces of which are coated with a monofunctional silane and / or silazane (A).

2. The surface-treated forsterite particles according to claim 1, wherein the average primary particle diameter of the forsterite particles is 0.05 to 30.0 μm.

3. 2. The surface-treated forsterite particles according to claim 1, wherein the monofunctional silane and / or silazane (A) is at least one selected from the group consisting of trimethylmethoxysilane, trimethylethoxysilane, vinyldimethylmethoxysilane, phenyldimethylmethoxysilane, hexamethyldisilazane, bis(ethyldimethyl)silylamine, bis(vinyldimethyl)silylamine and bis(phenyldimethyl)silylamine.

4. A resin dispersion comprising the surface-treated forsterite particles according to claim 1.

5. (I) firing a magnesium compound and silicon or a silicon compound at 900 to 1500° C.; (II) a step of heating the forsterite particles obtained in step (I) in the presence of a monofunctional silane and / or silazane (A); A method for producing surface-treated forsterite particles having the above structure.

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