Method for producing composite particles, and composite particles

Abstract

The purpose of the present invention is to provide a method for producing composite particles by which composite particles of a dissimilar material can be efficiently synthesized, and to provide composite particles having good fluidity and excellent dispersibility. A method for producing composite particles according to the present invention comprises: a step for preparing a first raw material containing any one element selected from the group consisting of copper, molybdenum and silver, and a second raw material containing one or more elements selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc and molybdenum; and a step for evaporating and cooling the prepared first and second raw materials by means of thermal plasma, the first raw material being evaporated by introducing the prepared first and second raw materials into the thermal plasma, and the evaporated first raw material being cooled, thereby generating composite particles. The composite particles comprise a second raw material and fine particles which are supported on the surface of the second raw material, have an average particle diameter of 0.5 nm or more and 300 nm or less and are produced from the first raw material.

Description

Technical Field

[0001] The present application relates to a method for producing composite particles obtained by combining large particles and small particles, and the composite particles. Background Art

[0002] In recent years, a visible light responsive photocatalyst has been proposed, which is a titanium oxide having nanometer-scale copper compound fine particles supported on its surface and which exhibits photocatalytic activity even under indoor light such as fluorescent lamps (see, for example, Patent Document 1).

[0003] As a method for producing titanium oxide supported with a copper compound, a production method based on a liquid phase method is known. For example, Patent Document 1 discloses a production method in which a reducing agent for reducing divalent copper to monovalent copper is added to a suspension containing titanium oxide having a rutile titanium oxide content of 50 mol% or more and a divalent copper compound.

[0004] In addition, as a method for producing composite particles using a plurality of raw materials, there is a method of producing large particles and small particles separately and attaching small particles to the surface of large particles by fluidized bed dry granulation or dry mechanical particle composite method (see, for example, Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: WO2013 / 002151

[0008] Patent Document 2: Japanese Patent Application Publication No. 2003-275281 Summary of the invention

[0009] In Patent Document 1, highly crystalline titanium oxide is synthesized by a vapor phase method, a divalent copper compound is added thereto, and after the suspension is stirred and prepared, a reducing agent such as an alkali metal, an alkaline earth metal, aluminum, zinc, an amalgam of an alkali metal or zinc, a hydride of boron or aluminum, a metal salt in a low oxidation state, hydrogen sulfide, a sulfide, a thiosulfate, oxalic acid, formic acid, ascorbic acid, a substance having an aldehyde bond, and an alcohol compound containing phenol is further added to reduce divalent copper (Cu(II)) to monovalent copper (Cu(I)).

[0010] However, the conventional manufacturing method has multiple steps and high manufacturing cost. In addition, since the synthesis is carried out in a liquid phase, the solvent that can be used is limited, and when the produced particles are used, complicated treatments such as solvent replacement are required. In addition, the adjustment of the reducing agent is difficult, and there is also the problem of the reducing agent remaining as an impurity.

[0011] In Patent Document 2, large particles and small particles are produced separately, and there is a process of mixing these large and small particles. This involves multiple steps and increases the production cost.

[0012] The present application has been made in view of the above-mentioned conventional problems, and an object of the present application is to provide a method for producing composite particles capable of efficiently synthesizing composite particles of different materials, and to provide composite particles having good fluidity and excellent dispersibility.

[0013] In order to achieve the above-mentioned purpose, the manufacturing method of the composite particles of the present application includes: a process of preparing a first raw material and a second raw material, wherein the first raw material includes an element selected from any one of copper, molybdenum, and silver, and the second raw material includes one or more elements selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and an evaporation and cooling process using thermal plasma, wherein the prepared first raw material and the second raw material are introduced into thermal plasma to evaporate the first raw material, and the evaporated first raw material is cooled to generate composite particles. The composite particles include the second raw material and fine particles generated from the first raw material and supported on the surface of the second raw material and having an average particle size of 0.5 nm or more and 300 nm or less.

[0014] In addition, in order to achieve the above-mentioned purpose, the composite particles of the present application include: base material particles, whose average particle size is greater than 0.3μm and less than 100μm, and contain a compound composed of an oxide of one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and fine particles present on the surface of the base material particles, whose average particle size is greater than 0.5nm and less than 300nm, and contain at least one of cuprous oxide, cupric oxide, copper, molybdenum oxide, silver, or silver oxide.

[0015] In addition, the composite particles of the present application include: base material particles having an average particle size greater than 0.3 μm and less than 100 μm, comprising a compound composed of an oxide of one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and fine particles present on the surface of the base material particles having an average particle size greater than 0.5 nm and less than 300 nm, comprising at least two of the following: a compound composed of an oxide of one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, and zinc; and cuprous oxide, cupric oxide, copper, molybdenum oxide, silver, or silver oxide.

[0016] According to the method for producing composite particles of the present application, composite particles of heterogeneous materials having a film or fine particles formed at a nanometer level and having excellent dispersibility can be easily provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a diagram for explaining an example of the flow of the method for producing composite particles according to the first embodiment.

[0018] Figure 2 It is a schematic cross-sectional view showing the cross-sectional structure of a thermal plasma device.

[0019] Figure 3 This is a schematic cross-sectional plan view of a state in which an electrode portion is cut in a horizontal direction in the thermal plasma device according to the first embodiment.

[0020] Figure 4 This is an electron microscope image of a composite raw material in the method for producing composite particles according to the first embodiment.

[0021] Figure 5 This is an electron microscope image of the composite particles obtained by the method for producing composite particles according to the first embodiment. DETAILED DESCRIPTION

[0022] The first method for producing composite particles includes: a process of preparing a first raw material and a second raw material, wherein the first raw material contains an element selected from any one of copper, molybdenum, and silver, and the second raw material contains one or more elements selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and an evaporation and cooling process using thermal plasma, wherein the prepared raw materials are introduced into thermal plasma to evaporate the first raw material, and the evaporated first raw material is cooled, thereby generating composite particles in which the surface of the second raw material carries microparticles generated from the first raw material and have an average particle size of not less than 0.5 nm and not more than 300 nm.

[0023] A second aspect of the method for producing composite particles may be such that, in the first aspect, in the evaporation and cooling step using thermal plasma, the thermal plasma is controlled so that 10 wt % or more of the second raw material is not evaporated.

[0024] A third aspect of the method for producing composite particles may be such that, in the first or second aspect, the second raw material has a higher melting point than the first raw material.

[0025] The fourth method for producing composite particles may be as follows: in any one of the first to third methods, in the step of preparing the first and second raw materials, the second raw material is particles, and the first raw material is supported or coated on the surface of the particles of the second raw material.

[0026] A fifth aspect of the method for producing composite particles may be that in any one of the first to fourth aspects, the second raw material is a particle, and the particle of the second raw material has no corners which are sharp portions resulting from the intersection of two surfaces but is spherical.

[0027] A sixth aspect of the method for producing composite particles may be that in any one of the first to fifth aspects, the first raw material and the second raw material are both particles, and the particle size of the first raw material is not more than 0.2 times the particle size of the second raw material.

[0028] A seventh aspect of the method for producing composite particles may be that in any one of the first to sixth aspects, the second raw material is a secondary particle obtained by granulating the primary particles.

[0029] The eighth aspect of the method for producing composite particles may be such that, in any one of the first to seventh aspects, in the evaporation and cooling step using thermal plasma, a cooling gas is supplied to a terminal end of the thermal plasma.

[0030] The manufacturing method of the composite particles of the 9th mode can be: in any one of the above-mentioned modes 1 to 8, in the evaporation and cooling process using thermal plasma, the thermal plasma is controlled in a manner so that the first raw material is evaporated preferentially, and at least one of the following is controlled: the temperature of the thermal plasma, the heating time using the thermal plasma, the temperature distribution of the thermal plasma, the gas type of the thermal plasma, the pressure of the thermal plasma, the supply position of the cooling gas of the thermal plasma, the flow rate, the gas type, the type of the composite raw material obtained by loading or coating the first raw material 61 on the surface of the particles of the second raw material 62, the average particle size of the primary particles and the secondary particles, the loading form, and the supply medium of the composite raw material.

[0031] The composite particles of the tenth embodiment include: base material particles having an average particle size greater than 0.3 μm and less than 100 μm, comprising a compound composed of an oxide of one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and particles containing copper, molybdenum, and silver elements present on the surface of the base material particles, having an average particle size greater than 0.5 nm and less than 300 nm, comprising at least one of cuprous oxide, cupric oxide, copper, molybdenum oxide, silver, or silver oxide.

[0032] The composite particles of the 11th embodiment include: base material particles whose average particle size is greater than 0.3μm and less than 100μm, and contain compounds composed of oxides of one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and fine particles present on the surface of the base material particles, whose average particle size is greater than 0.5nm and less than 300nm, and contain at least two of the following: compounds composed of oxides of one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, and zinc; and cuprous oxide, cupric oxide, copper, molybdenum oxide, silver, or silver oxide.

[0033] The composite particles of the twelfth embodiment may be: in the above-mentioned tenth or eleventh embodiment, the base material particles do not have corners as sharp parts generated by the intersection of two faces, but are spherical particles in which the difference between the radius B of the minimum sphere inscribed in the surface of the base material particle and the maximum value A of the distance from the center of the minimum sphere to the surface of the base material particle is less than three tenths of the maximum value A as shown in formula (1).

[0034] (AB)≤0.3×A···Formula (1)

[0035] The resin composition of the thirteenth aspect contains the composite particles of any one of the tenth to twelfth aspects.

[0036] A resin molded product according to a fourteenth aspect includes the composite particles according to any one of the tenth to twelfth aspects.

[0037] A metal or ceramic formed body according to a fifteenth aspect contains the composite particles according to any one of the tenth to twelfth aspects.

[0038] Hereinafter, a method for producing composite particles and composite particles according to an embodiment will be described in detail with reference to the drawings.

[0039] It should be noted that the embodiments described below all show general or specific examples. The numerical values, shapes, materials, constituent elements, the configuration positions and connection modes of constituent elements, steps, the order of steps, etc. shown in the following embodiments are an example, and their purport is not to limit the present invention. In addition, for the constituent elements in the following embodiments that are not recorded in the independent technical solutions showing the highest concept, they are described as arbitrary constituent elements. In each figure, the same symbols are given to substantially the same structures, and repeated descriptions are sometimes omitted or simplified.

[0040] In addition, various elements shown in the drawings are schematically shown only for the purpose of understanding the present invention, and their dimensional ratios, appearances, etc. may differ from actual objects.

[0041] (Implementation Method 1)

[0042] [Method for producing composite particles]

[0043] First, the method for producing composite particles according to the first embodiment uses Figures 1 to 3 Provide explanation. Figure 1 This is a diagram for explaining an example of the flow of the method for producing the composite particles 80 according to the first embodiment. Figure 2 1 is a schematic cross-sectional view showing the cross-sectional structure of the thermal plasma device 100 . Figure 3 A schematic cross-sectional plan view of the thermal plasma device according to the first embodiment is shown in a state where an electrode portion is cut in a horizontal direction. Figure 4: is an electron microscope image of the composite material 60 of the first embodiment. Figure 4 The total width is about 10μm. Figure 2 For the sake of convenience, the vertical upward direction is set as the Z direction, the right hand direction of the paper in the horizontal plane is set as the X direction, and the direction from the front side to the back side of the paper is set as the Y direction.

[0044] The method for producing the composite particles 80 of the first embodiment includes: a step of preparing a first raw material 61 and a second raw material 62; and a composite particle generation step of introducing each raw material into a thermal plasma 70 (see Figure 2 ) to evaporate the first raw material 61, and then cool it to generate composite particles 80 in which the second raw material 62 carries the microparticles generated from the first raw material 61 on the surface. That is, the generated composite particles 80 include the second raw material 62 and the microparticles generated from the first raw material 61 carried on the surface of the second raw material 62. The average particle size of the microparticles generated from the first raw material 61 is greater than 0.5 nm and less than 300 nm.

[0045] In the process of preparing raw materials, a first raw material 61 and a second raw material 62 are prepared, wherein the first raw material 61 contains one element selected from copper and molybdenum, and the second raw material 62 contains one element selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum.

[0046] In the composite particle generation step, each prepared raw material is introduced into a thermal plasma to evaporate the first raw material 61, and the evaporated first raw material 61 is cooled. In this way, composite particles 80 can be easily manufactured in which fine particles having an average particle diameter of 0.5 nm or more and 300 nm or less generated from the first raw material 61 containing one element selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum are supported on the surface of the second raw material 62 containing one element selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum.

[0047] According to the above-mentioned method for producing composite particles, composite particles having excellent dispersibility can be obtained.

[0048] Furthermore, in the step of preparing the first raw material 61 and the second raw material 62, the second raw material 62 may be particles, and the first raw material 61 may be supported or coated on the surface of the particles of the second raw material 62 to form the composite raw material 60. That is, the composite raw material 60 includes the second raw material 62 as particles and the first raw material 61 supported or coated on the surface of the second raw material 62. By using such a composite raw material 60, the evaporation efficiency of the first raw material 61 in the composite particle generation step can be improved, and the first raw material 61 can be uniformly supported on the surface of the second raw material 62.

[0049] In addition, if the second raw material 62 is a particle and the particles of the second raw material 62 do not have corners that are sharp parts caused by the intersection of two surfaces, then in the process of preparing the first raw material 61 and the second raw material 62, the first raw material 61 can be more evenly carried or thinly coated on the surface of the particles of the second raw material 62 when making the composite raw material 60, which can improve the evaporation efficiency of the first raw material 61 in the composite particle generation process and evenly carry the first raw material 61 on the surface of the particles of the second raw material 62.

[0050] In addition, if both the first raw material 61 and the second raw material 62 are particles, the particle size of the first raw material 61 only needs to be 0.2 times or less of the particle size of the second raw material 62. In this case, in the process of preparing the first raw material 61 and the second raw material 62, the first raw material 61 can be more uniformly supported or coated on the surface of the second raw material 62 particles when the composite raw material 60 is prepared. As a result, the evaporation efficiency of the first raw material 61 in the composite particle generation process can be improved, and the first raw material 61 can be uniformly supported on the surface of the second raw material 62.

[0051] The second raw material 62 may be secondary particles obtained by granulating primary particles. That is, even small particles that have poor fluidity and are difficult to transport can be transported by granulating them into secondary particles.

[0052] Hereinafter, a method for producing the composite particles 80 according to the first embodiment will be described by taking an example.

[0053] like Figure 1 As shown in the example, the manufacturing method of the composite particles 80 of the present embodiment 1 uses the prepared first raw material 61 (CuO in this case) and the second raw material 62 (TiO2 in this case). The method includes: a mixing step (step S1) of mixing the first raw material 61 while crushing, pulverizing, carrying or coating the first raw material 61 without crushing the second raw material 62; and a composite particle formation step (step S2) of introducing the composite raw material 60 obtained by step S1 into a thermal plasma device to evaporate the first raw material 61, cooling the evaporated first raw material 61 to micronize it, and carrying it on the surface of the second raw material 62.

[0054] Hereinafter, a method for producing the composite particle 80 will be described in more detail. The composite particle 80 is a composite particle in which Cu 2 O particles are supported on the surface of TiO 2 particles as base material particles, for example.

[0055] (a) In the mixing process (step S1), rutile TiO2 (particles of the second raw material 62) with an average particle size of 8 μm as a raw material of TiO2 and CuO (particles of the first raw material 61) with an average particle size of 1 μm as a raw material of Cu2O are mixed while crushing or pulverizing CuO without crushing TiO2. For example, TiO2 and CuO are prepared in a weight ratio of 99.5:0.5 and mixed using a mortar. Thus, a composite raw material 60 is obtained.

[0056] In addition, the composite raw material 60 introduced into the thermal plasma is used as follows Figure 4 As shown in (a), the material of the first raw material 61 to be evaporated is carried or coated on the surface of the second raw material 62. As a result, the first raw material 61 on the surface can be preferentially evaporated, and the fine particles generated from the first raw material 61 can be uniformly carried on the surface of the second raw material 62, so that the composite particles 80 that uniformly carry fine particles with small deviation in particle size can be manufactured.

[0057] In addition, the composite raw material 60 introduced into the thermal plasma can be Figure 4 The second raw material 62 shown in (b) is a particle, and the particles of the second raw material 62 do not have a sharp corner generated by the intersection of two surfaces. Figure 4 As shown in (c), the composite raw material 60 in which the first raw material 61 is more uniformly carried or coated on the surface of the second raw material 62. In addition, since there is no corner, the second raw material 62 is not easy to evaporate, and the evaporation of the second raw material 62 can be suppressed. In the present embodiment, only the first raw material 61 is carried and a part of the particles are crushed and coated on the surface of the second raw material 62. In addition, the particles can be further crushed and the area covered by the film can be increased by extending the treatment time or treating with the best force and method. In addition, the coating area can also be increased by the mixing ratio of the first raw material 61 and the second raw material 62. In addition, coating can also be performed by methods such as coating, evaporation, sputtering using solutions and gases, and a thin film can be coated. The obtained composite raw material 60 is subjected to thermal plasma treatment, thereby manufacturing composite particles 80 in which microparticles generated from the first raw material 61 with small deviation in particle size are uniformly carried on the surface of the second raw material 62.

[0058] In addition, the composite raw material 60 introduced into the thermal plasma only needs to have both the first raw material 61 and the second raw material 62 in the form of particles, and the particle size of the first raw material 61 is 0.2 times or less of the particle size of the second raw material 62. Thus, the composite raw material 60 can be obtained in which the first raw material 61 is more uniformly supported or coated on the surface of the second raw material 62. In addition, when the second raw material 62 is 0.3 μm or less, it is easy to evaporate, and by making it larger than 0.3 μm, the evaporation of the second raw material 62 can be suppressed. The obtained composite raw material 60 is subjected to thermal plasma treatment, thereby manufacturing composite particles 80 in which fine particles generated from the first raw material 61 with small deviation in particle size are uniformly supported on the surface of the second raw material 62.

[0059] In addition, if the particle size becomes smaller, the surface area becomes larger, so the fluidity of the particles becomes worse, and it becomes difficult to transport them in a dry state. However, in the composite raw material 60 introduced into the thermal plasma, it is sufficient that the second raw material 62 is a secondary particle obtained by granulating the primary particles using, for example, a binder as an organic matter. In this case, the secondary particles have a large particle size until they are introduced into the thermal plasma, have good fluidity, and can be transported in a dry state. Thereafter, after being introduced into the thermal plasma, the binder as an organic matter evaporates, the secondary particles decompose into primary particles, and the microparticles generated by the first raw material 61 are supported on the surface of the primary particles of the second raw material 62. Therefore, composite particles with a smaller particle size can be manufactured.

[0060] It should be noted that the mixing method of the raw materials is not limited to the above examples, and other methods that can be mixed, supported, or coated can also be used. In addition, the form of the raw materials is not limited to solid powders, and can also be liquid, gas, or a slurry in which solid powders are dispersed in a dispersion medium. In addition, composite particles can be obtained even if the raw materials are used without mixing.

[0061] (b) In the composite particle formation step (step S2 ), the composite raw material 60 obtained in the mixing step (step S1 ) is finely divided into first raw material 61 by a thermal plasma method and supported on the surface of second raw material 62 , thereby producing composite particles 80 .

[0062] In the process of atomizing the first raw material 61 of the composite raw material 60, Figure 2 A thermal plasma device 100 is shown.

[0063] <Thermal plasma device>

[0064] The thermal plasma device 100 includes at least a reaction chamber 20 as an example of a vacuum chamber, a material feeder 10, and a Figure 3 As shown, a thermal plasma generating unit includes a plurality of electrodes 43 and a composite particle recovery unit (here, a bag filter 50 ) as an example of a recovery device for recovering the generated composite particles.

[0065] The reaction chamber 20 is surrounded by a grounded cylindrical reaction chamber wall. The material supplier 10 supplies the composite raw material 60 into the reaction chamber 20 .

[0066] The thermal plasma generator generates thermal plasma at about 2000 to 10000° C. using AC power, for example. The thermal plasma generator has a plurality of electrodes 43 arranged at predetermined intervals on the side of the central portion of the reaction chamber 20 so as to penetrate from the outside to the inside and project the tip of each electrode into the internal space.

[0067] The bag filter 50 is disposed on the reaction chamber 20 side relative to the dry pump 30 , and collects the composite particles 80 generated in the reaction chamber 20 .

[0068] In this thermal plasma device 100, a thermal plasma 70 is generated in a reaction chamber 20. The first raw material of the composite raw material 60 supplied from the material supplier 10 is instantly evaporated by the generated thermal plasma 70 and rapidly cooled in the gas phase, thereby manufacturing composite particles 80 in which the first raw material is carried on the surface of the second raw material.

[0069] The micronization process (step S2) performed using a thermal plasma device is further composed of steps such as (1) introduction of raw materials and vacuum extraction, (2) introduction of gas and pressure adjustment, (3) start of discharge and plasma generation, (4) supply of raw materials, (5) formation of composite particles and (6) termination of discharge and recovery of composite particles.

[0070] The above steps are described below.

[0071] (1) First, the raw materials are introduced and vacuumed. Specifically, for example, a composite raw material 60 obtained by mixing TiO2 (the second raw material) and CuO (the first raw material) is introduced into the material feeder 10. Next, the reaction chamber 20, the piping provided with a composite particle recovery unit (not shown), and the material feeder 10 are evacuated using a dry pump 30, thereby reducing the influence of retained oxygen. It should be noted that, although not shown, the composite particle recovery unit includes a cyclone separator capable of classifying particles of any size or more and a bag filter 50 capable of recovering the desired composite particles 80.

[0072] (2) Then, gas is introduced and pressure is adjusted. Specifically, gas is supplied from a plurality of gas supply devices A and B to the material supplier 10 and the gas supply pipes 40 and 41 while adjusting the flow rate, and the reaction chamber 20 is adjusted to a predetermined pressure using the conductivity valve 31. In this embodiment, argon gas is introduced as the discharge gas, for example.

[0073] (3) Then, discharge begins to generate plasma. Figure 3A predetermined voltage is applied to the multiple electrodes 43 of the plasma generating part to discharge (arc discharge). Thereafter, the arc discharge is ignited, thereby generating thermal plasma 70. After the arc discharge is ignited, when the current applied to each electrode is stabilized, the composite raw material 60 is supplied from the material supply device 10 to the reaction chamber 20.

[0074] (4) Gases are supplied from the plurality of gas supply devices A and B to the material supply device 10, respectively, and the composite raw material 60 is supplied together with the gases to the reaction chamber 20. Specifically, the composite raw material 60 is sent from the material supply device 10 to the material supply pipe 42 together with the gases, and is introduced into the reaction chamber 20 together with the gases from the material supply pipe 42. For example, argon gas is used as a carrier gas for supplying the composite raw material 60 to the reaction chamber 20.

[0075] It should be noted that, around the material supply pipe 42, there is provided a device for feeding the composite raw material 60 and the composite particles 80 formed by the discharge in a certain direction ( Figure 2 In the figure, the gas is transported to the lower side (-Z direction) in the longitudinal direction of the paper. The gas is supplied from the gas supply pipes 40 and 41 in the above-mentioned certain direction.

[0076] (5) Then, composite particles 80 are formed. When the composite raw material 60 supplied to the reaction chamber 20 together with the gas passes through the region where the thermal plasma 70 is generated (hereinafter referred to as the thermal plasma 70), the first raw material 61 evaporates or gasifies (hereinafter referred to as "evaporation"), and the first raw material 61 is gasified. The thermal plasma 70 is controlled so that the first raw material 61 evaporates and the second raw material 62 does not evaporate. The control of the thermal plasma 70 can be achieved by controlling at least one selected from the temperature of the thermal plasma, the heating time by the thermal plasma, the gas type of the thermal plasma, the pressure of the thermal plasma, the supply position of the cooling gas of the thermal plasma, the flow rate, the gas type, the type of the composite raw material, the average particle size of the primary particles and the secondary particles, the supported form, and the supply medium of the composite raw material. For example, by adjusting the pressure, the thermal plasma 70 of about 2500 to 5000° C. can be generated in which CuO as the first raw material evaporates and TiO2 as the second raw material does not evaporate. In addition, for example, by changing the distance between the opposing electrodes of the plurality of electrodes 43 of the plasma generating portion, the number of electrodes, the frequency of the AC power applied to the electrodes, or the timing of the AC power applied to the electrodes, it is possible to set the temperature to any value within a wide range. In addition, by passing a gas downstream of the thermal plasma 70, it is possible to control the heating time. For example, there are many other combinations depending on the particle size and shape of the raw material, the temperature of the thermal plasma based on the plasma conditions, and the processing time. By controlling the thermal plasma as described above, it is possible to suppress the evaporation of the second raw material to, for example, 10 wt% or less while evaporating the first raw material.

[0077] On the other hand, in the above temperature range, TiO2 as the second raw material 62 melts because it is above the melting point and below the evaporation temperature. The mixed raw material of the molten particles of the second raw material 62 and the gas of the first raw material 61 flows in the above-mentioned certain direction due to the flow of gas from the gas supply pipes 40 and 41. At the moment of flowing out of the thermal plasma 70, the molten particles of the second raw material 62 are quenched in the gas phase and solidified into a roughly spherical shape. In addition, the gas generated from the first raw material 61 is also quenched and solidified in the gas phase, and is carried on the surface of the second raw material 62 as fine particles to generate composite particles 80. The cooling rate at this time is, for example, 10 4 ~10 5 K / second or so. In this case, the element with a high melting point solidifies first, and then the element with a low melting point solidifies. Therefore, the second raw material 62 containing the element with a high melting point becomes the matrix particle, and the composite particle 80 is formed in which the particles generated by the first raw material 61 containing the element with a low melting point are carried on the surface of the matrix particle. In the case of titanium and copper, titanium oxide, which is an oxide of titanium with a high melting point, becomes the matrix particle, and the composite particle containing the copper element containing copper with a low melting point is carried on the surface of the matrix particle.

[0078] It should be noted that the second raw material 62 can be evaporated in an amount of 10 wt% or less. Even if a portion of the second raw material 62 is evaporated, fine particles of the second raw material 62 with a high melting point are first generated on the surface of the unevaporated particles of the second raw material, and then fine particles of the first raw material 61 with a low melting point are generated. Therefore, fine particles of the first raw material 61 exist on the outermost surface of the second raw material 62. As a result, there is no effect on the characteristics, and if the evaporation is 10 wt% or less, there is no effect on the fluidity of the generated composite particles 80. In addition, by evaporating a portion of the second raw material 62 and supporting the fine particles generated from the first raw material 61 on the surface, the surface area that can be used for the reaction can be increased, and the performance can be further improved.

[0079] It should be noted that the cooling of the mixed raw material of the molten particles of the second raw material and the gas of the first raw material may also be natural cooling, but is not limited to this. For example, the cooling gas supply pipes 90 and 91 ( Figure 2 ) is introduced into the terminal portion of the thermal plasma 70 for cooling. By using the cooling gas to accelerate the cooling rate, the evaporation of the second raw material 62 can be suppressed while suppressing the aggregation of the particles generated by the gas of the first raw material 61, and composite particles that are more uniformly dispersed and supported can be manufactured. Figure 2In the figure, the gas supply pipes 40, 41, the material supply pipe 42, and the cooling gas supply pipes 90, 91 are connected to each other for the sake of simplicity, but this does not mean that they are always connected. The same or different gases can be selectively supplied to each pipe as needed.

[0080] (6) Then, the discharge is stopped and the generated composite particles 80 are recovered. The composite particles 80 generated by the thermal plasma 70 are recovered by the bag filter 50 due to the flow of gas (carrier gas and discharge gas) from the gas supply pipes 40 and 41 toward the composite particle recovery unit (not shown). Figure 2 As shown, the bag filter 50 is provided before the dry pump 30 for exhaust.

[0081] After the desired amount of composite raw material 60 is processed, the discharge is stopped and the generation of thermal plasma 70 is stopped. In addition, the composite particles 80 recovered by the bag filter 50 are taken out. At this time, the composite particles 80 can be taken out in an inert gas atmosphere such as nitrogen. By taking out in an inert gas atmosphere, oxidation of the composite particles 80 can be suppressed.

[0082] In the present embodiment 1, the example of using TiO2 and CuO as the raw material of the composite particle 80 is described, however, as the raw material of TiO2, if it is anatase TiO2, rutile TiO2, brookite TiO2 or their mixture, since the evaporation temperature is the same no matter which one, it can be used. The crystal form of the matrix particles can be controlled by controlling the ratio of these raw materials. In addition, regarding the Cu2O source, no matter which Cu and Cu compounds such as CuO, Cu, Cu2O, CuCl2 or their mixture can be evaporated, it can be used. The ratio of Cu2O of the particles containing the copper element can be controlled by controlling the ratio of these raw materials.

[0083] In the first embodiment, an example in which a solid powder raw material is used as the first raw material 61 is described. However, a liquid containing Cu can also be used because it can be evaporated.

[0084] In the first embodiment, an example in which CuO is used as the first raw material is described, but the first raw material is not limited thereto. A raw material containing one element selected from copper, molybdenum, and silver may be used as the first raw material.

[0085] In addition, in the first embodiment, an example of using TiO2 as the second raw material of the composite particles 80 is described, but the second raw material is not limited thereto. A raw material containing one or more elements selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum can be used as the second raw material.

[0086] It should be noted that, in the manufacturing method of the composite particles 80 of the present embodiment, a thermal plasma method is used, but other methods may be used as long as the first raw material such as CuO can be evaporated and rapidly cooled to produce microparticles with an average particle size of 300 nm or less. In the thermal plasma method, high-frequency thermal plasma, direct current arc plasma, or alternating current arc plasma can be used. As a method other than the thermal plasma method, a flame method using a burner, a laser ablation method, or a thermal decomposition method using a high-frequency heating method can be used.

[0087] It should be noted that although an example using only argon as the gas is described, it is not limited to this. At least one of the materials supply gas (carrier gas), discharge gas, and the gas (cooling gas) (not shown) introduced from the cooling gas supply pipes 90 and 91 into the terminal portion of the thermal plasma 70 can be used by adding oxygen to an inert gas such as argon.

[0088] In addition, in the case of synthesizing composite particles of TiO2 and Cu2O, if only inert gas is used, part of the oxygen from the raw material generated by evaporation of the raw material cannot participate in the reaction, and there is a situation where a part of oxygen is missing and metal Cu is generated. It should be noted that in the mixed gas of the inert gas and oxygen, the content of oxygen is, for example, 0.1vol% to 50vol%. By adding oxygen to the inert gas, the lack of oxygen can be suppressed and the proportion of Cu2O can be increased.

[0089] In addition, at least one of the carrier gas, discharge gas and cooling gas can be used after adding oxygen and hydrogen or carbon-based reducing gas to inert gas such as argon. Oxygen and / or reducing gas can be used to control the oxidation and crystal structure of the oxides of the first raw material and the second raw material. It should be noted that if too much oxygen is added, the proportion of CuO in Cu2O, CuO, and Cu constituting the particles containing copper elements in the first raw material increases, and the proportion of Cu2O decreases. Therefore, by further adding hydrogen or carbon-based reducing gas, the proportion of Cu2O can be optimized. In addition, since Cu2O is generated at a lower temperature than the oxide of the parent material particles, the gas added with hydrogen or carbon-based reducing gas can be introduced as cooling gas from the terminal end of the thermal plasma 70. In addition, the cooling gas can also be supplied from the bottom of the reaction chamber 20 to the top (Z direction) in a manner that becomes convection relative to the thermal plasma.

[0090] In addition, in the above, the oxidation and crystal structure of the oxide of the base material particles of the second raw material and / or the particles containing the copper element in the first raw material are controlled by controlling the atmosphere such as oxygen and / or reducing gas, but it is not limited to this. For example, the ratio of Cu2O, CuO, and Cu in the raw material containing the copper element in the first raw material among the raw materials can also be controlled to control the ratio of Cu2O in the particles containing the copper element. In this way, the ratio of Cu2O in the particles containing the copper element in the first raw material can be controlled without using a reducing agent.

[0091] [Composite particles]

[0092] Next, use Figure 5 The composite particles according to the first embodiment will be described. Figure 5 : is an electron microscope image of a composite particle 80 obtained by the method for producing a composite particle 80 according to the first embodiment (hereinafter referred to as the composite particle of Example 1). Figure 5 The total width is about 10 μm.

[0093] In the composite particle 80 of the first embodiment, Figure 5 The electron microscope image and elemental analysis show that the surface of spherical TiO2 particles with an average particle size of more than 5 μm and less than 10 μm is supported by Cu2O particles with an average particle size of more than 0.5 nm and less than 300 nm. That is, in the composite particles, the TiO2 particles with rutile as the main component are the matrix particles, and the Cu2O particles are present on the surface of the matrix particles. Since the Cu2O particles are present on the surface of the matrix particles, the surface of the TiO2 particles as the matrix particles is not completely covered, so that it is possible to obtain photocatalytic activity while obtaining high antibacterial and antiviral properties.

[0094] In addition, if Figure 5 As shown, the matrix particles generated by the second raw material 62 are roughly spherical. That is, there are no corners as sharp parts caused by the intersection of two faces, and the particles are spherical. In addition, the value of sphericity represented by the ratio (AB) / A of the difference (AB) between the radius B of the minimum sphere inscribed in the surface of the particle and the maximum value A of the distance from the center of the minimum sphere to the surface of the particle relative to the maximum value A is less than 0.1. Although it also depends on the material properties, as long as the sphericity is less than 0.3, the dispersibility is good. If the sphericity is less than 0.1, the dispersibility is even better, so it is preferred. Therefore, the composite particles of this embodiment 1 have good fluidity, so when they are mixed with resins, ceramics, and metals to form a molded body, the material has high dispersibility and can be evenly dispersed in the molded body.

[0095] The average particle size of each of the primary particles of the matrix particles and the particles containing the copper element can be obtained by, for example, calculating the number average of 100 particles in an electron microscope or a transmission electron image. The average particle size can be measured by, for example, a dynamic light scattering method.

[0096] In addition, in the present embodiment 1, a mixture of TiO2 and CuO in a weight ratio of 99.5:0.5 is used as a raw material, but the mixing ratio of the composite particles 80 can also be controlled by changing the mixing ratio of TiO2 and CuO. If the proportion of CuO is excessively less than 0.01wt%, Cu2O is reduced and the antiviral property is reduced. On the contrary, if the proportion of CuO is increased, TiO2 is covered by Cu2O, the antibacterial and antiviral properties of Cu2O become stronger, and the photoresponse is reduced, but the degradation during resin mixing can be suppressed, and coloring can be suppressed compared to Cu2O alone. The proportion of CuO can be increased to 10wt%. If it is greater than 10wt%, there is a situation where the photoresponse cannot be fully obtained.

[0097] It should be noted that, in addition to this, the oxide of the matrix particles containing the second raw material may be an oxide or composite oxide containing one or more elements selected from aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum. If the oxide or composite oxide contains the above selected elements, the particles are white, so coloring can be suppressed compared to the case of using Cu2O alone.

[0098] It should be noted that, in addition to this, the supported particles generated from the first raw material may also be particles containing copper and molybdenum elements, which contain at least one of cuprous oxide, cupric oxide, copper, molybdenum oxide, silver or silver oxide. Since molybdenum oxide is a white particle, it is different from using Cu alone. 2O Compared with the case of , coloring can be suppressed.

[0099] Therefore, if the amount of the composite particles mixed in a resin composition, a resin molded product or a resin sheet-like molded product containing the composite particles produced by thermal plasma is 5 wt % or less, the composite particles can be mixed while maintaining the color of the main component.

[0100] As the resin, the composite particles are kneaded into a resin mainly composed of polypropylene, but the present invention is not limited thereto and may be, for example, a resin mainly composed of polyethylene, polystyrene, acrylic polymer, methacrylic polymer, polyethylene terephthalate (PET), polycarbonate, or the like.

[0101] Furthermore, in a metal or ceramic molded body containing composite particles produced by thermal plasma, for example, if the amount is 5 wt % or less, it can be mixed while maintaining the color of the main component.

[0102] It should be noted that the present application includes the case where any of the various embodiments and / or examples described above are appropriately combined to exert the effects of the various embodiments and / or examples.

[0103] Industrial Applicability

[0104] According to the manufacturing method of composite particles of the present application, composite particles can be easily obtained, which use the second raw material of the selected element as the base material particles, and the surface of the base material particles of the second raw material has microparticles generated from the first raw material with an average particle diameter of more than 0.5nm and less than 300nm, and the above-mentioned first raw material contains at least one of cuprous oxide, cupric oxide, copper, molybdenum oxide, silver or silver oxide. According to the composite particles, it has high catalytic performance or antibacterial and antiviral properties, and has high dispersibility. In addition, there is little mixing of impurities, and composite particles can be produced in large quantities in a short time, which is useful as a manufacturing method for composite particles.

[0105] Description of Reference Numerals

[0106] 10 material supplier, 20 reaction chamber, 30 dry pump, 31 conductivity valve, 40, 41 gas supply pipes, 42 material supply pipe, 43 electrode, 50 bag filter, 60 composite raw material, 61 first raw material, 62 second raw material, 70 thermal plasma, 80 composite particles, 90, 91 cooling gas supply pipes.

Claims

1. A method for producing composite particles, the method comprising: a step of preparing a first raw material and a second raw material, wherein the first raw material includes an element selected from the group consisting of copper, molybdenum, and silver, and the second raw material includes one or more elements selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and The first raw material and the second raw material prepared are introduced into the thermal plasma to evaporate the first raw material by utilizing the evaporation and cooling process of the thermal plasma, and the evaporated first raw material is cooled to generate composite particles. The composite particles include the second raw material and fine particles generated from the first raw material and having an average particle diameter of 0.5 nm to 300 nm, which are supported on the surface of the second raw material.

2. The method for producing composite particles according to claim 1, wherein: In the evaporation and cooling step using thermal plasma, the thermal plasma is controlled so as not to evaporate more than 10 wt % of the second raw material.

3. The method for producing composite particles according to claim 1, wherein: The second raw material has a higher melting point than the first raw material.

4. The method for producing composite particles according to any one of claims 1 to 3, wherein: In the step of preparing the first raw material and the second raw material, the first raw material and the second raw material are composite raw materials, The composite raw material includes the second raw material in the form of particles and the first raw material supported on or coated on the surface of the second raw material.

5. The method for producing composite particles according to any one of claims 1 to 3, wherein: The second raw material is a particle, and the particle of the second raw material does not have a corner which is a sharp portion generated by the intersection of two surfaces.

6. The method for producing composite particles according to any one of claims 1 to 3, wherein: The first raw material and the second raw material are both particles, and the average particle size of the first raw material is 0.2 times or less of the average particle size of the second raw material.

7. The method for producing composite particles according to any one of claims 1 to 3, wherein: The second raw material is secondary particles obtained by granulating primary particles.

8. The method for producing composite particles according to any one of claims 1 to 3, wherein: In the evaporation and cooling step using thermal plasma, a cooling gas is supplied to a terminal end portion of the thermal plasma.

9. The method for producing composite particles according to any one of claims 1 to 3, wherein: In the evaporation and cooling process using thermal plasma, the thermal plasma is controlled in such a way that the first raw material is evaporated preferentially by controlling the temperature of the thermal plasma, the heating time of the thermal plasma, the temperature distribution of the thermal plasma, the gas type of the thermal plasma, the pressure of the thermal plasma, the supply position, flow rate, gas type of the cooling gas of the thermal plasma, the type of composite raw material on the surface of the particles of the second raw material supported or coated with the first raw material, the average particle size of the primary particles and the secondary particles, the supporting form, and at least any one of the supply medium of the composite raw material.

10. A composite particle comprising: Base material particles having an average particle size of greater than 0.3 μm and less than 100 μm, comprising a compound consisting of an oxide of one element selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and The fine particles present on the surface of the base material particles have an average particle diameter of 0.5 nm to 300 nm, and contain at least one of cuprous oxide, cupric oxide, copper, molybdenum oxide, silver, or silver oxide.

11. A composite particle comprising: Base material particles having an average particle size of greater than 0.3 μm and less than 100 μm, comprising a compound consisting of an oxide of one element selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, zinc, and molybdenum; and The fine particles present on the surface of the matrix particles have an average particle size of 0.5 nm or more and 300 nm or less and include at least two of the following: A compound consisting of an oxide of one element selected from the group consisting of aluminum, titanium, zirconium, hafnium, iron, yttrium, niobium, tantalum, silicon, calcium, magnesium, tungsten, indium, tin, germanium, nickel, and zinc; and Cuprous oxide, cupric oxide, copper, molybdenum oxide, silver or silver oxide.

12. The composite particle according to claim 10 or 11, wherein The base material particles have no corners which are sharp portions resulting from the intersection of two surfaces and have a spherical shape satisfying the formula (1). (AB)≤0.3×A ···Formula (1) Here, B is the radius of the smallest sphere inscribed in the surface of the matrix particle, A is the maximum value of the distance from the center of the minimum spherical surface to the surface of the base material particle.

13. A resin composition comprising: Resin, and The composite particles according to claim 10 or 11 in the resin.

14. A resin molded article comprising: Resin, and The composite particles according to claim 10 or 11 in the resin.

15. A metal and ceramic formed body comprising: Resin, and The composite particles according to claim 10 or 11 in the resin.

Images