JP2013040090A - Method of producing metal oxide particle with spherical shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of simply and efficiently producing metal oxide particles with spherical shape, the particles comprising a general metal oxide, by using a flame fusion method that can be implemented at low cost and is applicable to industrial mass production.SOLUTION: The method of producing the metal oxide particle with spherical shape includes a step of heating one or more nonvaporizable metal chelate powder in a thermal fluid to pyrolyze an organic component in the powder for removal and to oxidize a metal component.

Description

  The present invention uses a flame melting method that can be carried out at a low cost and can be applied to industrial mass production. Solid spherical metal oxide particles composed of general metal oxides can be easily and efficiently produced. It relates to a method for manufacturing.

  Spherical metal oxide particles have a high utility value due to high fluidity and high filling properties derived from their characteristic forms. For example, spherical metal oxide particles made of silica or alumina are widely used, such as fillers blended with resins, foundry sand, abrasive grains, and thermal spray materials. In particular, in recent years, it is also spreading to applications that require high reliability, such as additives for semiconductor encapsulants, and in the future there will be a growing need for spheroidization not only for silica and alumina but also for other metal oxides. It seems to be a thing.

  As a method for producing spherical metal oxide particles, a flame melting method in which a raw material compound is introduced into a high-temperature flame and spherical metal oxide particles are obtained through melting, liquefaction, and cooling is the most common in terms of cost.

  However, examples reported so far relate to silica (for example, Patent Document 1) or alumina (for example, Patent Documents 2 and 3), and there are almost no examples of spheroidization of other metal oxides. Absent.

  One reason for this is that, conventionally, metal particles, metal oxide particles, and the like are used as raw materials in the flame melting method, and thus manufacturing conditions have to be strict.

  Specifically, since the metal particles are gradually oxidized from the surroundings, uniformity is a problem, and it is necessary to increase the heating time. Moreover, when using metal oxide particles, they must be heated once to their melting points or higher to melt.

  As described above, there is an example in which spherical silica particles are produced by the flame melting method. When silica is used as a raw material, the melting point is about 1650 ° C., which is considered to be lower than the melting point of a general metal oxide. However, when the heating temperature is adjusted to the vicinity of the melting point, there is a problem that the time until melting to the inside must be lengthened.

  Moreover, although there is a track record of producing spherical alumina particles by the flame melting method, the melting point of alumina is about 2050 ° C., which is higher than that of silica and has poor thermal conductivity. Non-Patent Document 1 describes that in the case of alumina, it is necessary to increase the amount of heat transferred to the raw material powder by increasing the flame temperature and increasing the residence time in the flame. Therefore, it is necessary to control the supply of a flame burner having a special nozzle structure and raw material powder, which lacks versatility.

Japanese Patent Laid-Open No. 3-170319 JP 2008-120673 A JP 2008-162825 A

Shinji Murakami et al. 28, 34-35 (2009)

  As described above, the flame melting method is very useful as a means for producing spherical metal oxide particles. However, the raw materials such as silica and alumina are easily melted, but only a general metal oxide, particularly rare earth oxidation is used. There is no track record in spheroidizing high-melting point oxides such as products.

  Therefore, the present invention uses a flame melting method that can be carried out at a low cost and can be applied to industrial mass production, and enables simple and efficient solid spherical metal oxide particles made of general metal oxides. It is an object to provide a method that can be manufactured.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, if non-vaporizable metal chelate powder is used as a raw material instead of metal oxide that has been widely used in the past, even general metal oxides other than silica and alumina can be used in a highly versatile flame melting method. The present invention was completed by finding that real spherical particles can be easily produced.

  In the method for producing solid spherical metal oxide particles according to the present invention, one or more non-vaporizable metal chelate powders are heated in a thermal fluid to thermally decompose and remove organic components in the powders. And a step of oxidizing the metal component.

  As the chelating agent for preparing the non-vaporizable metal chelate powder, an aminocarboxylic acid chelating agent is suitable, and more specifically, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and nitrilo At least one selected from triacetic acid is preferred. The metal chelate formed from the aminocarboxylic acid chelating agent is non-vaporizable. In addition, the chelating agent is inexpensive and easily available, and the metal chelate formed from the chelating agent has high stability and has an advantage of being easily purified because it is easily crystallized.

  According to the method of the present invention, a solid spherical particle made of a metal oxide, which has been difficult to manufacture, can be easily obtained by using a flame melting method that can be implemented at low cost and can be applied to industrial mass production. And it can manufacture efficiently. In addition, the solid spherical metal oxide particles produced by the method of the present invention have extremely high fluidity because the porosity is equal to zero and the sphericity is high, and industrial convenience is high. Therefore, the present invention is very useful industrially as a production technique for solid spherical metal oxide particles useful as resin fillers, foundry sand, abrasive grains, thermal spray materials and the like used for semiconductor elements.

FIG. 1 is a schematic view showing an example of a flame gun spray gun that can be used in the method of the present invention. FIG. 2 is an electron micrograph of solid spherical yttrium oxide particles obtained by the method of the present invention. (1) is an appearance photograph, and (2) is a cross-sectional photograph. FIG. 3 is an electron micrograph of solid spherical erbium oxide particles obtained by the method of the present invention. (1) is an appearance photograph, and (2) is a cross-sectional photograph. FIG. 4 is an electron micrograph of solid spherical titanium oxide particles obtained by the method of the present invention. (1) is an appearance photograph, and (2) is a cross-sectional photograph. FIG. 5 is an X-ray diffraction chart of solid spherical yttrium oxide particles obtained by the method of the present invention. FIG. 6 is an X-ray diffraction chart of solid spherical erbium oxide particles obtained by the method of the present invention. FIG. 7 is an X-ray diffraction chart of solid spherical titanium oxide particles obtained by the method of the present invention.

  In the method of the present invention, solid vapor metal oxide particles are obtained by heating a non-vaporizable metal chelate powder in a thermal fluid to thermally decompose and remove organic components in the powder and oxidize the metal components. Get.

  The non-vaporizable metal chelate powder can be prepared from a chelating agent and a metal compound corresponding to the target metal oxide particles.

  The chelating agent used in the method of the present invention is not particularly limited as long as it can form a solid non-vaporizable metal chelate with a general metal at normal temperature and pressure. Examples of the chelating agent include ethylenediaminetetraacetic acid (EDTA), 1,2-cyclohexanediaminetetraacetic acid, dihydroxyethylglycine, diaminopropanoltetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminediacetic acid, ethylenediaminedipropionic acid, hydroxyethylenediaminetriacetic acid. , Glycol ether diamine tetraacetic acid, hexamethylenediamine tetraacetic acid, ethylenediamine di (o-hydroxyphenyl) acetic acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, 1,3-diaminopropanetetraacetic acid, 1,2-diaminopropanetetraacetic acid Nitrilotriacetic acid, nitrilotripropionic acid, methylglycine diacetic acid, triethylenetetramine hexaacetic acid, ethylenediamine disuccinic acid, 1,3-diaminopropane disuccinic acid, glutami Water-soluble aminocarboxylic acid-based chelating agents such as acid-N, N-diacetic acid, aspartic acid-N, N-diacetic acid, etc .; phosphonic acid-based chelating agents such as hydroxyethylidene diphosphonic acid; nitrilotris (methylenephosphone) Acid) and aminodiamine acid chelating agents such as ethylenediaminetetra (methylenephosphonic acid); carboxylic acid-phosphonic acid chelating agents such as phosphonobutanetricarboxylic acid; hydroxycarboxylic acids such as gluconic acid, citric acid, tartaric acid and malic acid Mention may be made of system chelating agents. A polymer in which two or more of the above chelating agents are polymerized can also be used.

  A diketone chelating agent such as acetylacetone cannot be used in the present invention because the resulting metal chelate is vaporizable.

  As the chelating agent used in the present invention, an aminocarboxylic acid chelating agent is suitable. The aminocarboxylic acid chelating agent can be easily bonded to any metal ion to obtain a non-vaporizable metal chelate, and the metal chelate can be isolated as a crystal to be highly purified. More preferred aminocarboxylic acid chelating agents include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and nitrilotriacetic acid. These chelating agents are inexpensive and readily available, and metal chelates formed from these chelating agents have advantages such as high stability and easy crystallization because they are easily crystallized.

  The metal compound that is a raw material of the metal chelate powder is not particularly limited as long as it can easily form a chelating agent and a metal chelate in a solvent. Examples of the metal compound include oxides, simple metals, hydroxides, halide salts such as chloride salts and bromide salts, carbonates, nitrates, sulfates, and the like.

  Examples of the metal constituting the metal compound, that is, the metal constituting the metal oxide particles that are the target compound of the present invention include alkaline earth metals such as calcium and magnesium; light metals such as aluminum; titanium, chromium, manganese, iron , Transition metals such as cobalt, nickel, copper and zinc; rare earth metals such as yttrium, lanthanum, cerium and erbium.

  The metal chelate powder according to the present invention can be produced by reacting a chelating agent with a metal compound in a solvent, and then separating from the solvent.

  The amount of the chelating agent and the metal compound used may be a ratio in which both are almost not excessive or insufficient in consideration of the coordination number of the chelating agent and the coordination number of the metal compound. If one of them is excessively present in the reaction solution, a large amount of impurities remain after the reaction, which is uneconomical and troublesome to purify the metal chelate as the target compound. More specifically, for example, when a chelating agent and a metal compound react one-on-one to form a metal chelate, the number of moles of the metal compound is 0.9 mol or more and 1.1 mol with respect to 1 mol of the chelating agent. Preferably, the amount is 0.95 mol or more and 1.05 mol or less, more preferably 0.98 mol or more and 1.02 mol or less.

  Water may be used as the solvent. The concentration of the chelating agent and the metal compound in the reaction solution may be adjusted as appropriate, and may be, for example, 5% by mass or more and 50% by mass or less.

  The reaction temperature and reaction time can also be adjusted as appropriate. More specifically, the reaction temperature and reaction time may be determined by preliminary experiments and the like. Depending on the reactivity of the chelating agent and the metal compound, a metal chelate powder may be obtained even if it is dissolved in a solvent and then immediately post-treated without taking any reaction time.

  After completion of the reaction, a metal chelate powder can be obtained by a conventional method. For example, the metal chelate, which is the target compound, is crystallized by adding a poor solvent, concentrating the reaction solution, cooling, or a combination of two or more of these, filtering this, washing and drying. Alternatively, the reaction solution may be concentrated to dryness and then recrystallized.

  The metal chelate powder may be a salt such as a hydrogen salt or an ammonium salt.

  The obtained metal chelate powder may be adjusted in particle size and shape as necessary. That is, in the flame melting method, since the raw material powder must be stably supplied to the thermal spraying machine, it is preferable that the shape has a small aspect ratio and the particle size is as uniform as possible. As a result, the stable feedability of the raw material powder is greatly improved. Therefore, coarse powder may be pulverized by treating the obtained metal chelate powder with a ball mill, a rod mill, or a hammer mill. Alternatively, coarse particles or excessively fine particles may be removed by sieving to obtain a powder having a narrow particle size distribution and a uniform particle size.

  The particle size of the metal chelate powder is not particularly limited as long as it does not impair the fluidity, but is preferably about 10 μm or more and 150 μm or less. Outside this range, the powder hose that transports the powder from the powder supply device to the thermal spray gun may become clogged, resulting in a non-uniform feed, which may result in incomplete thermal decomposition of the organic components.

  When the metal chelate powder is introduced into the thermal fluid, its organic component is thermally decomposed. Then, the metal component remaining after the thermal decomposition is oxidized to produce a metal oxide, and the metal oxide becomes solid spherical particles during flight.

  The metal chelate used in the method of the present invention is non-vaporizable. That is, the metal chelate according to the present invention does not vaporize even when heated, and the chelating agent portion, which is an organic component, is thermally decomposed before vaporization. Therefore, when the metal chelate according to the present invention is heated to a temperature equal to or higher than the pyrolysis temperature, the metal chelate is always thermally decomposed before being vaporized, so that the metal is oxidized and a metal oxide is generated. In addition, if the metal chelate that is a raw material in the flame melting method is vaporized before thermal decomposition, the oxide particles generated by thermal decomposition after that become too fine, or the yield of oxide particles Is extremely reduced.

  The decomposition temperature of the metal chelate according to the present invention is approximately 250 ° C. or more and 400 ° C. or less. Accordingly, the heating temperature of the metal chelate powder in the hot fluid may be 400 ° C. or higher. On the other hand, the upper limit of the heating temperature is not particularly limited, but can be, for example, 3000 ° C. or lower, preferably 2000 ° C. or lower, more preferably 1500 ° C. or lower, and further preferably 1000 ° C. or lower. Such a heating temperature is clearly lower than the heating temperature in the conventional flame melting method using a metal oxide or the like as a raw material.

  The raw material powder in this step may be composed of only one kind of metal chelate, or may be a mixture of a plurality of kinds of metal chelates mechanically. For example, when mixing and using ethylenediaminetetraacetic acid yttrium ammonium salt and ethylenediaminetetraacetic acid europium ammonium salt as raw material powder, by introducing the raw material into a thermal fluid, yttrium oxide and europium oxide Solid spherical metal oxide particles containing can be formed.

  By heating the obtained non-vaporizable metal chelate powder in a thermal fluid, the organic component in the powder is thermally decomposed and removed, and the metal component is oxidized, and the solid spherical metal oxide according to the present invention Get particles.

  The method used when introducing the metal chelate powder into the thermal fluid is to generate a thermal fluid at a temperature necessary for pyrolyzing the organic components and obtaining solid spherical metal oxide particles. Although not particularly limited, for example, a commonly used thermal spraying method or a thermal fluid generator of a thermal spraying apparatus can be used. That is, it is only necessary that the metal chelate powder as a raw material can be thermally decomposed by the thermal energy of the thermal spray flame as a thermal fluid, and if the metal chelate can be heated to a temperature at which it is thermally decomposed, the thermal spraying method and the thermal spraying conditions are particularly limited. Not. Specifically, a flame spraying method in which gas is burned to form a thermal spray flame as a thermal fluid, a high-speed gas flame spraying method, a plasma spraying method in which a thermal flame is formed as a thermal fluid by discharge, or a thermal fluid as There is a cold spray method that sprays with a high-speed working gas, but any method can be used as long as the metal chelate powder can be pyrolyzed and a thermal fluid (spray flame) is formed. More preferred is flame spraying, which can be performed at low cost.

  As an example of a method for producing solid spherical metal oxide particles using a metal chelate powder, this method is performed by flame spraying using a spray gun 100 (for example, 6P-II manufactured by Sulzer Metco) as shown in FIG. Solid spherical metal oxide particles can be obtained using the raw materials of the embodiment. The thermal spray gun 100 includes an oxygen-combustible gas supply hole 1 for supplying an oxygen-combustible gas, a carrier gas supply hole 2 for supplying a raw material carrier gas for conveying a powder raw material, and a raw material supply hole 3 for supplying a raw material. And the nozzle 4 and the like. The raw material supplied from the raw material supply hole 3 is injected by the carrier gas, introduced into a cylindrical spray flame (frame) 5, and uniformly heated and decomposed to generate metal oxide particles. A solid spherical shape can be formed while being conveyed by the thermal spray flame 5, and solid spherical metal oxide particles can be obtained by the metal oxide powder recovery device. The metal oxide powder recovery device is not particularly limited, and examples thereof include a cyclone type powder recovery device, a bag filter, and a combination thereof.

  In the flame spraying method, the maximum temperature of the flame is about 3200 ° C. in the case of acetylene flame, which is a sufficient temperature (400 ° C. or higher) to decompose the metal chelate that is the raw material of the present embodiment. Further, the flame temperature of other thermal spraying methods is said to be about 2700 ° C. by high-speed gas flame spraying (kerosene) and about 10,000 ° C. by plasma spraying, and the metal chelate can be decomposed by any thermal spraying method. Therefore, the raw material of the present embodiment is a solid spherical metal oxide by easily heating the metal chelate of the raw material to the decomposition temperature, decomposing it, and converting it into a metal oxide under the conventional general spraying method and spraying conditions. Product particles can be obtained.

  The solid spherical metal oxide particles formed by the method of the present invention described above will be described below.

The metal oxide particles obtained by the method of the present invention are solid bodies having almost no pores and are spherical with a high sphericity. For example, FIG. 2 shows an electron micrograph of the appearance and cross section of yttria (Y ₂ O ₃ ) particles obtained by thermal spraying a powder made of a metal chelate of yttrium and ethylenediaminetetraacetic acid as a raw material powder. Show. From this photograph, it can be seen that it is a solid sphere with high sphericity.

  According to the method for producing a solid spherical metal oxide particle sprayed coating according to the present invention described above, the raw material powder heated in the process of thermal spraying decomposes without vaporizing and has a very small particle size. It becomes particles, and after melting and spheroidizing, it can be cooled and crystallized while flying to obtain solid spherical metal oxide particles. In addition, as described above, the metal chelate powder that is the raw material of the method of the present invention decomposes at 400 ° C. or lower, and therefore, even when sprayed at a very low temperature compared to a plasma spraying method such as flame spraying. Solid spherical metal oxide particles can be obtained.

  In addition, according to the raw material powder according to the present invention, a metal oxide film can be formed if the metal chelate as a raw material can be decomposed by heat. can do. Specifically, any thermal spraying method that sprays a thermal spray material with a thermal fluid at a temperature higher than the decomposition temperature of the metal chelate, such as the flame spraying described above, high-speed gas flame spraying, arc spraying, plasma spraying, cold spray, etc. Such a thermal spraying method may be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

Examples 1 to 3 Production of solid spherical metal oxide particles (1) Preparation of raw metal chelate powder In an aqueous solvent, yttrium oxide, erbium oxide or titanium chloride and ethylenediaminetetraacetic acid were reacted in equimolar amounts. Then, the raw material metal chelate powder of Table 1 was prepared by crystallization from this aqueous solution.

(2) Production of metal oxide particles Metal oxide particles were produced by the flame spraying method shown in Table 2 using the crystal powder as a raw material. The used thermal spraying machine has a thermal spray gun having a shape schematically shown in FIG. The supply amount of the raw metal chelate powder was 10 g / min in Example 1, 9 g / min in Example 2, and 0.3 g / min in Example 3. Moreover, the obtained metal oxide particles were recovered by collecting the free-falling particles with an adhesive tape.

(3) Analysis The appearance of the metal oxide particles obtained above was observed with an electron microscope. Further, the obtained metal oxide particles were embedded in a resin and cut, and the cross section was observed with an electron microscope. As a result, it was confirmed that all were solid spheres having a diameter of about 0.2 to 50 μm. The electron micrograph of each metal oxide particle of Examples 1-3 is shown in FIGS. The obtained metal oxide particles were analyzed by X-ray diffraction. The obtained X-ray diffraction charts are shown in FIGS. From the obtained results, it was confirmed that the metal oxide particles of Examples 1 to 3 were each composed of yttrium oxide, erbium oxide, and a rutile-type and anatase-type titanium oxide mixture.

1: Oxygen-combustible gas supply hole 2: Carrier gas supply hole 3: Raw material supply hole 4: Nozzle 5: Thermal spray flame 100: Thermal spray gun

Claims (3)

A method for producing solid spherical metal oxide particles comprising:
A solid comprising a step of heating one or more kinds of non-vaporizable metal chelate powders in a thermal fluid to thermally decompose and remove organic components in the powders and oxidize the metal components A method for producing spherical metal oxide particles.   The production method according to claim 1, wherein an aminocarboxylic acid chelating agent is used as the chelating agent.   The production method according to claim 2, wherein at least one selected from ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and nitrilotriacetic acid is used as the aminocarboxylic acid chelating agent.