Inorganic powders and methods for manufacturing the same, and powder treatment agents for use in the manufacturing method.

Abstract

The aim is to provide an inorganic powder with a film exhibiting excellent insulation, flowability, and water resistance. A film is formed on the surface of the inorganic powder, the film containing Zr, N, and Si, with the N / Si molar ratio and Zr / Si molar ratio within specified ranges.

Description

Technical Field

[0001] This invention relates to an inorganic powder with excellent insulation, water resistance and flowability, which is useful for all industrial products that use inorganic powders, such as electronic devices and electronic components, as well as a method for manufacturing the same and a powder treatment agent for the manufacturing method. Background Technology

[0002] In recent years, with the miniaturization and increasing functionality of electronic and electrical equipment, the electronic components used in them are required to possess excellent magnetic properties. Therefore, the inorganic powders used in electronic components need to have high insulation properties. Furthermore, in addition to insulation, other properties are required, such as flowability during powder pressing and water resistance of the coating that can be used for extended periods in various environments. Therefore, inorganic powders with a coating on their surface possessing these properties have been developed.

[0003] For example, Patent Document 1 discloses a powder for pressing magnetic cores, wherein the powder for pressing magnetic cores is a powder for pressing magnetic powder having a first film and a second film on the surface of the first film. In the two films, the first film is composed of a partially hydrolyzed organic alkoxysilane and / or its precursor, and the second film is composed of alkali-silicic acid glass.

[0004] Patent Document 2 discloses a particle film forming treatment solution containing at least one silicon compound, an organometallic compound, and a metal salt, which is composed of an alkoxysilyl group, an alkoxymethylene silyl group, and a siloxane bond.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 4436172 Patent Document 2: Japanese Patent Application Publication No. 2019-157189 Summary of the Invention The problem the invention aims to solve However, the powder for pressed magnetic cores described in Patent Document 1, due to the formation of two films, may have insufficient flowability or insufficient water resistance, thus potentially making it unsuitable for long-term performance maintenance under various environments. Furthermore, the film-forming treatment liquid for particles in Patent Document 2 may not achieve sufficient flowability. Therefore, the object of the present invention is to provide an inorganic powder with excellent insulation, flowability, and water resistance, a method for manufacturing the same, and a powder treatment agent for the manufacturing method.

[0006] means for solving problems In order to solve the above problems, the inventors conducted in-depth research and found that by using a specified powder treatment agent to form a film on the surface of inorganic powder, the film contains Zr, N and Si, and the N / Si molar ratio and Zr / Si molar ratio are within a specified range, thereby obtaining inorganic powder with excellent insulation, flowability and water resistance, thus completing the present invention.

[0007] That is, the present invention is as follows, etc. (1) An inorganic powder with a film, comprising: an inorganic powder; and a film formed on the surface of the inorganic powder, containing at least Zr, N and Si, wherein the N / Si molar ratio is in the range of 0.010 to 1.000 and the Zr / Si molar ratio is in the range of 0.10 to 10.00; (2) The inorganic powder with a film described in (1), wherein the film further contains C, and the C / Si molar ratio in the film is in the range of 0.20 to 20.00; (3) The inorganic powder with a film described in (1) or (2), wherein the film does not contain at least one selected from P, Ti and Cr; (4) A powder treatment agent, wherein the mixture contains at least zirconium ions, an alkoxysilane compound and an aqueous medium, wherein the alkoxysilane compound contains a nitrogen-containing alkoxysilane, and the zirconium ions are in the range of 4 to 400 parts by mass relative to 100 parts by mass of the alkoxysilane compound, and the aqueous medium is in the range of 100 to 5000 parts by mass. (5) The inorganic powder treatment agent described in (4), wherein the free acidity (pt) of the inorganic powder treatment agent is in the range of 1.0 to 100.0. (6) The inorganic powder treatment agent described in (4) or (5), wherein the alkoxysilane compound contains a tetraalkoxysilane and a silane coupling agent having an amino group; (7) The inorganic powder treatment agent described in any one of (4) to (6), wherein the alkoxysilane compound contains a tetraalkoxysilane and an epoxy-containing silane coupling agent, and the epoxy-containing silane coupling agent is in the range of 2 to 200 parts by mass relative to 100 parts by mass of the alkoxysilane compound other than the epoxy-containing silane coupling agent; (8) A method for manufacturing an inorganic powder with a film, comprising the following steps: heating a composition containing inorganic powder and an inorganic powder treatment agent described in any one of (4) to (7) to evaporate the volatile components in the composition and form a film on the surface of the inorganic powder.

[0008] Invention Effects According to the present invention, an inorganic powder with excellent insulation, flowability and water resistance, a method for manufacturing the same, and a powder treatment agent for the manufacturing method can be provided. Detailed Implementation

[0009] One embodiment of the present invention is an inorganic powder with a coating, comprising an inorganic powder and a coating formed on the surface of the inorganic powder, wherein the coating contains at least Zr, N, and Si, with an N / Si molar ratio in the range of 0.010 to 1.000 and a Zr / Si molar ratio in the range of 0.10 to 10.00. The inorganic powder used as a raw material is not particularly limited in particle size, shape, composition, etc., as long as it is a powder composed of inorganic substances. From the perspective of its usefulness as a material for electronic components, a magnetic inorganic powder is preferred as the raw material. As a magnetic inorganic powder, it is preferable to contain iron. Furthermore, the inorganic powder is preferably a conductor, for example, with a conductivity of 1 × 10⁻⁶. 6 S / m or higher, or 1×10 5 S / m or higher.

[0010] Examples of inorganic powders containing iron include Fe (pure iron) and metal compounds, such as Fe-Si, Fe-Si-Cr, Fe-Ni, Fe-Si-Al, Fe-Cr, Fe-Co, Fe-Nd, and Fe amorphous metal compounds. Other examples of inorganic powders include metal oxides, metal nitrides, and metal borides. Examples of inorganic metal compounds include barium titanate (BaTiO3), boron nitride (BN), ferrite (MFe2O4; M represents a divalent metal element), lead zirconate titanate {Pb(Zr,Ti)O3}, aluminum oxide (Al2O3), silicon carbide (SiC), zinc oxide (ZnO), zirconium dioxide (ZrO2), and zircon (ZrO2). SiO2), magnesium olivine (2MgO) SiO2), mullite (3Al2O3) 2SiO2), massive talc (MgO) SiO2), cordierite (2MgO) 2Al2O3 Examples of silicon nitride include 5SiO2, aluminum nitride (AlN), and silicon nitride (Si3N4).

[0011] There are no particular restrictions on the particle size of inorganic powders. The cumulative 50% volume particle size (D50) is typically 0.1 μm or larger, but can be 0.5 μm or larger, or 1.0 μm or larger. It is also typically below 1000 μm, but can be below 500 μm, 300 μm or smaller, or 150 μm or smaller. There are also no particular restrictions on the shape of inorganic powders. The aspect ratio is typically below 50, but can be below 20, 10 or smaller, or typically above 1. Furthermore, the aspect ratio of inorganic powders refers to the ratio of the major axis to the minor axis. Here, the major and minor axes of inorganic powders are obtained by averaging the lengths of the longest and shortest axes of 100 randomly selected inorganic powders in the image analysis of a scanning electron microscope.

[0012] The film-coated inorganic powder has a film containing at least Zr, N, and Si, and may also contain other elements. Examples of other elements include components found in the inorganic powder itself. In addition, examples include H, O, and C from moisture or raw materials, or elements contained in zirconium-containing ion sources. However, it is preferable that it does not contain at least one element selected from P, Ti, and Cr. Here, "does not contain" means substantially not containing, but does not exclude the presence of trace amounts.

[0013] In this method, it is particularly preferred that the molar ratio of N to Si (N / Si) in the film is within a specified range, and that the molar ratio of Zr to Si (Zr / Si) in the film is also within a specified range. By ensuring that their molar ratios are within the specified range, the film, which exhibits superior flowability, water resistance, and insulation, can be uniformly formed on the surface of the inorganic powder.

[0014] The aforementioned N / Si molar ratio is preferably in the range of 0.010 to 1.000, more preferably in the range of 0.020 to 0.700, and even more preferably in the range of 0.030 to 0.500. Furthermore, the aforementioned Zr / Si molar ratio is preferably in the range of 0.10 to 10.00, more preferably in the range of 0.20 to 7.00, and even more preferably in the range of 0.40 to 4.00.

[0015] Furthermore, when the film also contains C, the molar ratio of C to Si in the film (C / Si) is preferably within a specified range. The C / Si mass ratio is preferably in the range of 0.20 to 20.00, more preferably in the range of 0.30 to 10.00, and particularly preferably in the range of 0.50 to 5.00.

[0016] The contents of Zr, N, Si, and C in the film can be determined by the following method. First, the inorganic powder with the film is cured with a curing resin (or a combination of resin and curing agent). Then, the cured material is mechanically ground and a thin film is prepared using ion milling. Next, the elemental composition of the inorganic powder film in the thin film is analyzed using energy-dispersive X-ray spectroscopy (EDS) attached to a field emission scanning electron microscope (FE-SEM). The content of each element can be calculated based on the obtained elemental analysis values ​​(intensities).

[0017] The thickness of the film is not particularly limited, but is preferably in the range of 1 nm to 100 nm, more preferably in the range of 2 nm to 70 nm, and particularly preferably in the range of 5 nm to 50 nm.

[0018] The thickness of the film can be measured by observing the prepared thin film using a field emission scanning electron microscope (FE-SEM) or a transmission electron microscope (TEM).

[0019] This method also relates to a powder processing liquid (inorganic powder processing agent) capable of stably manufacturing the film-coated inorganic powder (e.g., insulating magnetic powder) of this method. There are no particular limitations on the powder processing liquid as long as it is a mixture containing at least an alkoxysilane compound (including nitrogen-containing alkoxysilanes), zirconium ions, and an aqueous medium; other components may also be included. The zirconium ions contained in the powder processing liquid are preferably in the range of 4 to 400 parts by mass relative to 100 parts by mass of the alkoxysilane compound, more preferably in the range of 10 to 100 parts by mass. Furthermore, the aqueous medium contained in the powder processing liquid is preferably in the range of 100 to 5000 parts by mass relative to 100 parts by mass of the alkoxysilane compound, more preferably in the range of 300 to 3000 parts by mass. By using this powder treatment solution, films with N / Si molar ratios of 0.010 to 1.000 and Zr / Si molar ratios of 0.10 to 10.00, respectively, can be manufactured more stably. Furthermore, the powder treatment solution may or may not contain silicone resin and / or pigments as additives, but it is preferable that they do not.

[0020] The powder processing liquid of this method contains at least a nitrogen-containing alkoxysilane compound as an alkoxysilane compound. Examples of nitrogen-containing alkoxysilane compounds include silane coupling agents having an amino group (organoalkoxysilanes having an amino group), such as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, etc. This nitrogen-containing alkoxysilane compound can be used alone or in combination of two or more.

[0021] In addition to nitrogen-containing alkoxysilane compounds, various organic alkoxysilanes (silane coupling agents) can be used as alkoxysilane compounds in the powder processing liquid of this method. Here, in order to adjust the N / Si molar ratio in the film to an appropriate range, tetraalkoxysilane is preferably used as a material that does not introduce N into the film.

[0022] There are no particular limitations on tetraalkoxysilanes; examples include tetraethoxysilane (tetraethyl orthosilicate), tetramethoxysilane (tetramethyl orthosilicate), tetrabutoxysilane (tetrabutyl orthosilicate), tetraisopropoxysilane (tetraisopropyl orthosilicate), and tetrapropoxysilane (tetrapropyl orthosilicate). Furthermore, these tetraalkoxysilanes can be used alone or in combination of two or more.

[0023] The powder processing liquid may also contain alkoxysilanes other than the aforementioned alkoxysilanes (nitrogen-containing alkoxysilanes and tetraalkoxysilanes) as alkoxysilanes. Examples include vinyltrimethoxysilane and vinyltriethoxysilane, which are vinyl-containing silane coupling agents; and epoxy-containing silane coupling agents such as 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, 3-glycidyletheroxypropylmethyldimethoxysilane, 3-glycidyletheroxypropyltrimethoxysilane, and 3-glycidyletheroxypropyltriethoxysilane. Furthermore, these silane coupling agents can be used alone or in combination of two or more.

[0024] As described above, the alkoxysilane compound in this method must contain one or more nitrogen-containing alkoxysilane compounds, or it may contain one or more other alkoxysilane compounds. For example, the powder processing solution may be a processing solution containing tetraalkoxysilane and an amino-containing silane coupling agent, or it may be a processing solution containing tetraalkoxysilane, an amino-containing silane coupling agent, and an epoxy-containing silane coupling agent. The alkoxysilane compound may contain a hydrolysate of the alkoxysilane compound. Furthermore, when the powder processing solution of this method contains an epoxy-containing silane coupling agent, the content of the epoxy-containing silane coupling agent relative to 100 parts by mass of the alkoxysilane compound other than the epoxy-containing silane coupling agent is preferably in the range of 2 to 200 parts by mass, more preferably in the range of 10 to 100 parts by mass. By using this powder processing solution, films with a C / Si molar ratio in the range of 0.20 to 20.00 can be manufactured more stably. Furthermore, the powder processing solution of this method may or may not contain components other than Zr, N, and Si. "Not containing" means intentionally not in proportion, but unavoidable contamination is not excluded. However, it is preferable that the powder processing solution of this method does not contain at least one of P, Ti, and Cr.

[0025] The powder processing solution of this method contains zirconium ions. There are no particular limitations on the water-soluble zirconium compounds used as the zirconium ion source; examples include hexafluorozirconic acid, zirconium sulfate tetrahydrate, zirconium oxynitrate dihydrate, zirconium chloride, and zirconium oxyacetate. Furthermore, these reagents can be used in combination, one or more of them. Here, "water-soluble" as used in this specification means that more than 1 g can dissolve in 1 L of water at 25°C.

[0026] There are no particular limitations on the combination of the above-mentioned alkoxysilane compounds with water-soluble zirconium compounds. Examples of such combinations include: tetrabutoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and zirconium oxynitrate dihydrate; tetraisopropoxysilane, vinyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and zirconium chloride; tetrapropoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, and zirconium oxyacetate; tetraethoxysilane, 2-(3,4-epoxycyclohexane)ethyltriethoxysilane, etc. Combinations of methoxysilane, 3-aminopropyltrimethoxysilane, and hexafluorozirconic acid; combinations of tetramethoxysilane, vinyltriethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, and zirconium sulfate tetrahydrate; combinations of tetrabutoxysilane, vinyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,4-dimethyl-butylene)propylamine, and zirconium oxynitrate dihydrate; combinations of tetraisopropoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and zirconium chloride; tetrapropoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexane) Combinations of alkyl(2-(aminoethyl)-3-aminopropyltrimethoxysilane and zirconium acetate oxysilane; combinations of tetraethoxysilane, vinyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane and hexafluorozirconic acid; combinations of tetramethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane and zirconium sulfate tetrahydrate; combinations of tetrabutoxysilane, vinyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane and zirconium nitrate dihydrate; tetraisopropoxysilane, vinyl... Combinations of trimethoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, 3-aminopropyltriethoxysilane and zirconium chloride; combinations of tetrapropoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-triethoxysilyl-N-(1,4-dimethyl-butylene)propylamine and zirconium acetate; combinations of tetraethoxysilane, vinyltriethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and hexafluorozirconic acid; combinations of tetramethoxysilane, vinyltrimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and zirconium sulfate tetrahydrate;Combinations of tetrabutoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane and zirconium oxynitrate dihydrate; combinations of tetraisopropoxysilane, vinyltriethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane and zirconium chloride; combinations of tetrapropoxysilane, vinyltrimethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane and zirconium acetate; combinations of tetraethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane and hexafluorozirconic acid; tetramethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, 3-triethoxysilyl-N-( Combinations of 1,4-dimethyl-butylene)propylamine with zirconium sulfate tetrahydrate; combinations of tetrabutoxysilane, vinyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane with zirconium oxynitrate dihydrate; combinations of tetraisopropoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane with zirconium chloride; combinations of tetrapropoxysilane, vinyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane with zirconium oxyacetate; combinations of tetraethoxysilane, vinyltrimethoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane with hexafluorozirconic acid.

[0027] The aqueous medium in the powder treatment agent of this method is not particularly limited as long as it is water or a mixture of water and water-mixed organic solvents (containing more than 50% water by mass based on the volume of the aqueous medium). As for the water-mixed organic solvent, there are no particular restrictions as long as it is a solvent that mixes with water; examples include ketone solvents such as acetone and methyl ethyl ketone; amide solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol, and isopropanol; ether solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. These water-mixed organic solvents can be mixed with water in one or more ways. Furthermore, there are no particular restrictions on the water used; for example, ion-exchanged water (conductivity: less than 1 μS / cm) and distilled water can be used.

[0028] The free acidity (pt) of the powder treatment agent in this method is generally preferably in the range of 1.0 to 100.0, more preferably in the range of 2.0 to 75.0, and even more preferably in the range of 3.0 to 50.0. The free acidity can be adjusted using commercially available acidic or alkaline solutions. Examples of acidic solutions include aqueous solutions of sulfuric acid, nitric acid, hydrochloric acid, acetic acid, formic acid, oxalic acid, and hydrofluoric acid; examples of alkaline solutions include aqueous solutions of ammonia, ammonium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0029] Free acidity (pt) refers to the amount of "T-11" (ml) obtained by titrating 10ml of powder treatment agent with "T-11" manufactured by Parkerizing Co., Ltd. of Japan after adding 2-3 drops of "D-11" manufactured by Parkerizing Co., Ltd. of Japan (1ml=1 point).

[0030] Other components mentioned above include, for example, additives such as surfactants and lubricants. These additives can be included in the film to a degree that does not impair the effects of the invention. Furthermore, regarding lubricants, they can be further disposed on the film of this embodiment as a lubricating film.

[0031] The production of inorganic powder with a film in this manner can be carried out by contacting the aforementioned powder treatment agent with the inorganic powder and then heating it, thereby evaporating the volatile components of the powder treatment agent to form a film on the inorganic powder. More specifically, the production of inorganic powder with a film can be carried out by heating a composition containing a powder treatment agent and inorganic powder, causing the volatile components in the composition (the volatile components in the powder treatment agent) to evaporate. The contact between the powder treatment agent and the inorganic powder can be carried out by mixing or other contact methods. Furthermore, in order to stably and efficiently produce inorganic powder, it is preferable to heat the aforementioned composition in air or an inert gas (nitrogen, carbon dioxide, helium, neon, argon, krypton, xenon, radon, etc.) to evaporate the volatile components in the composition. The evaporation of volatile components can be carried out, for example, using a spray dryer. In addition, after the volatile components have evaporated, a step of forming another film on the surface of the inorganic powder with a film can be included, for example, a step of forming a lubricating film by contacting a lubricant. There are no particular limitations on the contact method; examples include impregnation with a lubricant and mixing with a lubricant. Furthermore, in the manufacture of inorganic powders, after contact with a lubricant, a step of drying the surface of the inorganic powder that has contacted the lubricant may be included. There are no particular limitations on the drying method; examples include heating in air or an inert gas. Through the above manufacturing methods, inorganic powders with a lubricating film can be obtained.

[0032] The heating of the composition can be carried out slowly to reach the specified temperature, or it can be carried out in stages to ultimately reach the specified temperature. There is no particular upper limit to the specified temperature, but it is preferably below 400°C, more preferably below 300°C, and particularly preferably below 200°C. Furthermore, there is no particular limitation on the drying temperature of the surface of the inorganic powder with a film that has come into contact with the lubricant, but it is preferably below 200°C, more preferably below 100°C.

[0033] The inorganic powder with a film in this embodiment is typically press-molded when used as an industrial product (e.g., electronic components). Under pressure of 13 MPa, the inorganic powder with a film in this embodiment exhibits excellent insulation even as a thin film, and demonstrates excellent flowability when filled into a mold during press-molding. Furthermore, it exhibits excellent water resistance. Therefore, the inorganic powder with a film in this embodiment is useful as a material for all industrial products that use inorganic powders, such as various electronic devices and electronic components manufactured by press molding.

[0034] In particular, due to its excellent insulation and flowability, the inorganic powder with a film according to this embodiment not only enables the miniaturization and high performance of various electronic devices and components such as inductors, capacitors, thermistors, and varistors, but also maintains its performance even in various environments due to its excellent water resistance, making it extremely useful in practical applications. Furthermore, the inorganic powder with a film according to this embodiment includes not only powders with a film on their surface, but also powders with one or more films (e.g., oxide films) between the inorganic powder and the film.

[0035] Example Next, embodiments and comparative examples are shown for practical processing to specifically illustrate the effects of the present invention. Furthermore, the embodiments do not limit the scope of the present invention in any way.

[0036] Inorganic powder Inorganic powders are manufactured using commercially available atomized pure iron powder (manufactured by Heganes, ABC100.29, volume average particle size (D50) = 106 μm, hereinafter referred to as "pure iron powder") or Fe-5.5%Si-4%Cr atomized powder (soft magnetic powder manufactured by Atomize Processing Co., Ltd. of Japan, volume average particle size (D50) = 10 μm, hereinafter referred to as "alloy powder"), as described below.

[0037] (Preparation of powder treatment solution) As shown in Table 1, the powder treatment agents of Examples 1-23 and Comparative Examples 3-9 were prepared by mixing the various components and pure water in specified amounts. The free acidity was adjusted using sulfuric acid, sodium hydroxide, etc. Furthermore, the symbols shown in the "Component Symbols" column of Table 1 are as follows.

[0038] 1: Hexafluorozirconic acid 2: Zirconium sulfate tetrahydrate 3: Zirconium oxynitrate dihydrate 4: Zirconium chloride 5: Zirconium oxyacetate 6: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane 7: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane 8: N-2-(aminoethyl)-3-aminopropyltriethoxysilane 9:3-Aminopropyltrimethoxysilane 10:3-Aminopropyltriethoxysilane 11: 3-Triethoxysilyl-N-(1,4-dimethyl-butylene)propylamine 12: N-Phenylacetyl-3-aminopropyltrimethoxysilane 13: Vinyltrimethoxysilane 14: Vinyltriethoxysilane 15: 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane 16:3-Glycidyl etheroxypropyltrimethoxysilane 17:3-Glycidyl etheroxypropylmethyldimethoxysilane 18:3-Glycidyl etheroxypropyltriethoxysilane 19: Tetraethoxysilane 20: Tetramethoxysilane 21: Tetrabutoxysilane 22: Tetraisopropoxysilane 23: Tetrapropoxysilane A: 67.5% nitric acid B: 85% Phosphoric A [Table 1]

[0039] A value: relative to 100 parts by mass of alkoxysilane compound, the mass parts of zirconium ions. B value: relative to 100 parts by mass of alkoxysilane compound, parts by mass of aqueous medium. C-value: The percentage by mass of an epoxy-containing silane coupling agent relative to 100 parts by mass of an alkoxysilane compound other than an epoxy-containing silane coupling agent. (Method for manufacturing inorganic powders with a film) 50g of the inorganic powders shown in Table 1 were weighed separately to prepare the powder treatment agents for Examples 1-23 and Comparative Examples 3-8 shown in Table 1. The treatment liquid addition amount shown in Table 1 was added to the inorganic powders, and the mixture was stirred at 25°C for 5 minutes. Then, as a drying step, the stirred mixture was placed in a thermostat maintained at 120°C for 30 minutes to obtain inorganic powders 1-31 with a film. In addition, inorganic powders 24 and 25 did not form a film, and the inorganic powders remained unchanged from the original raw materials.

[0040] (Measurement of N / Si molar ratio, Zr / Si molar ratio, C / Si molar ratio, and film thickness) After preparing the embedding resin using the EpomountA kit (manufactured by RefineTec Co., Ltd.; 27-770), the embedding resin was mixed with the inorganic powder with a film from the examples and comparative examples. The mixture was poured into a mold and allowed to cure. After mechanically grinding the cured material, thin films were fabricated using an ion milling machine (IM-4000 model manufactured by Hitachi High-Tech). Elemental analysis of the film of the inorganic powder with a film in the thin films was performed using the EDS (Electronics System Microscope) included with a field emission scanning electron microscope (FE-SEM, JSM-F100 model manufactured by NEC Corporation). The content of each element was determined based on the obtained elemental analysis values, and the molar ratios of N / Si, Zr / Si, and C / Si were calculated. Furthermore, the film thickness was measured by observation using the FE-SEM. These results are shown in Table 2.

[0041] (Evaluation of insulation performance) Using the MCP-PD51 and Hiresta-UX or Loresta-GX powder resistivity measurement systems manufactured by Nitto Seiko Analytech Co., Ltd. (formerly Mitsubishi Chemical Analytech Co., Ltd.), pressure was applied to a specified amount of inorganic powder with a film, and the volume resistivity (Ω) was measured. (cm). Furthermore, assuming a pressure of 13 MPa, the volume resistivity under the specified pressure is measured. The evaluation criteria are as follows.

[0042] Compared to the volume resistivity of pure iron powder without a film (Comparative Example 1) at a pressure of 13 MPa, the volume resistivity of pure iron powder with a film at a pressure of 13 MPa is: 1.0×10 4 More than twice is marked with "◎". 1.0×10 3 More than twice but less than 1.0 × 10 4 The multiple is "0". 1.0×10 2 More than twice but less than 1.0 × 10 3 The multiple is represented by "△". Less than 1.0 × 10 2 The multiple is marked with "×".

[0043] Compared to the volume resistivity of the alloy powder without a film (Comparative Example 2) at a pressure of 13 MPa, the volume resistivity of the alloy powder with a film at a pressure of 13 MPa is: 1.0×10 6 More than twice is marked with "◎". 1.0×10 5 More than twice but less than 1.0 × 10 6 The multiple is "0". 1.0×10 4 More than twice but less than 1.0 × 10 5 The multiple is represented by "△". Less than 1.0 × 10 4 The multiple is marked with "×". These results are shown in Table 2.

[0044] In addition, "〇" or "◎" are judged as practical level.

[0045] (Liquidity assessment) The evaluation was conducted according to JIS Z 2502:2020. However, the outlet inner diameter of the Hall effect flowmeter used was Φ4.5mm. The evaluation criteria are as follows.

[0046] Compared to inorganic powders that do not form a film, a flow-out time of less than 1.1 times is marked with a "◎". Compared to inorganic powders that do not form a film, a flow-out time that is more than 1.1 times but less than 1.2 times is considered "0". Compared to inorganic powders that do not form a film, a flow-out time that is more than 1.2 times but less than 1.3 times is considered "△". An efflux time that is more than 1.3 times longer than that of inorganic powders that do not form a film is marked with an "×".

[0047] These results are shown in Table 2. Furthermore, “〇” or “◎” is judged as the practical level.

[0048] (Evaluation of water resistance) At room temperature (25℃), 2g of inorganic powder 1-31 and 50g of pure water were weighed and added to a 100ml beaker. The mixture was stirred with a glass rod to agitate the inorganic powder for 1 minute. After standing for 3 minutes, the supernatant was collected, and 20g of 35% hydrochloric acid was added. After stirring for 30 minutes, 100ml of the supernatant was prepared using dihydrate (DI). The Si component, one of the film components, was quantitatively analyzed using ICP-C (Thermo Ficher Scientific iCAP7400). The evaluation criteria are as follows.

[0049] Less than 0.3 mg / L is marked with a "◎". A concentration above 0.3 mg / L but less than 0.7 mg / L is marked "0". A concentration above 0.7 mg / L but less than 1.0 mg / L is marked with a "△". Above 1.0 mg / L is marked with "×".

[0050] These results are shown in Table 2. Furthermore, “〇” or “◎” is judged as the practical level.

[0051] [Table 2]

[0052] Industrial applicability The inorganic powder with a coating according to embodiments of the present invention possesses excellent insulation, flowability, and water resistance, making it suitable for all applications requiring these properties. Furthermore, by using the powder treatment agent according to embodiments of the present invention, a coating containing Zr, N, and Si can be formed on the surface of the inorganic powder, and the properties of this coating (insulation, flowability, and water resistance) can be imparted to the inorganic powder. Thus, the powder treatment agent according to embodiments of the present invention is useful for the manufacture of inorganic powders suitable for various applications.

[0053] Cross-referencing of related applications This application claims priority based on Japanese Patent Application No. 2023-182923 filed with the Japan Patent Office on October 25, 2023, all of the disclosures of which are incorporated herein by reference.

Claims

1. An inorganic powder with a film, wherein, have: Inorganic powders; as well as A film is formed on the surface of the inorganic powder, containing at least Zr, N and Si, wherein the N / Si molar ratio is in the range of 0.010 to 1.000 and the Zr / Si molar ratio is in the range of 0.10 to 10.

00.

2. The inorganic powder with a film according to claim 1, wherein, The film also contains C, and the C / Si molar ratio in the film is in the range of 0.20 to 20.

00.

3. The inorganic powder with a film according to claim 1 or 2, wherein, The membrane does not contain at least one selected from P, Ti and Cr.

4. An inorganic powder treatment agent, wherein, It is a mixture containing at least zirconium ions, alkoxysilane compounds, and an aqueous medium. The alkoxysilane compound contains nitrogen-containing alkoxysilanes. The zirconium ions are in the range of 4 to 400 parts by mass relative to 100 parts by mass of the alkoxysilane compound, and the aqueous medium is in the range of 100 to 5000 parts by mass.

5. The inorganic powder treatment agent according to claim 4, wherein, The free acidity (pt) of the inorganic powder treatment agent is in the range of 1.0 to 100.

0.

6. The inorganic powder treatment agent according to claim 4, wherein, The alkoxysilane compound contains a tetraalkoxysilane and a silane coupling agent having an amino group.

7. The inorganic powder treatment agent according to claim 4, wherein, The alkoxysilane compound contains a tetraalkoxysilane and a silane coupling agent with an epoxy group. The amount of the epoxy-containing silane coupling agent is in the range of 2 to 200 parts by mass relative to 100 parts by mass of the alkoxysilane compound other than the epoxy-containing silane coupling agent.

8. A method for manufacturing an inorganic powder with a film, wherein, The process includes heating a composition containing inorganic powder and any one of claims 4 to 7 to evaporate the volatile components in the composition and form a film on the surface of the inorganic powder.

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