JP2005015303A - Method of manufacturing spherical powder, spherical oxide powder and oxide powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing spherical powder by which a powdery raw material is stably supplied in an excellent dispersion state and the the production of macro-particles or unmelted particles caused by aggregated particles is suppressed. <P>SOLUTION: A treating agent such as stearic acid is added to the powdery raw material 100a supplied to a spherical powder manufacturing apparatus 10 to prevent the aggregation. The powdery raw material 100a to which the treating agent is added is charged into combustion flame F produced by a burner 30 to be melted and after being melted, is moved to the outside of the combustion flame F to be cooled and solidified to be made spherical. The production of the macro-particles is suppressed moreover by jetting an aggregation breaking gas into the inside from the outer periphery side of a powdery raw material supply tube to break the aggregation of the powdery raw material 100a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３８】
表１、図４、図５に示すように、試料２〜５において、処理剤を無添加の試料１に比較して安息角が若干ではあるが低く、またステアリン酸の添加量が多いほど、安息角が小さくなる傾向を示している。これに対し、嵩密度は、試料２〜５においてステアリン酸の添加量に関わらずほぼ一定となっている。
これにより、ステアリン酸の添加によって原料粉末１００ａの流動度が高められると言える。
【００３９】
続いて、得られた原料粉末１００ａ（試料１〜１２）を、球状粉末製造装置１０のフィーダ（図示無し）に投入し、バーナ３０で生じる燃焼炎Ｆによって球状化させた。
このとき、バーナ３０では、酸素供給系統３２から酸素を７５ ｌ（リットル）／ｍｉｎの流量で供給し、燃焼ガス供給系統３３からＬＰＧを１５ ｌ／ｍｉｎの流量で供給して燃焼炎Ｆを発生させ、原料粉末供給系統３１ではキャリアガスとしてＮ_２ガスを７０ ｌ／ｍｉｎの流量で供給しつつ、フィーダを１．２０ｒｐｍで駆動することで原料粉末１００ａを燃焼炎Ｆ中に供給して溶融するようにした。
そして、溶融時の原料粉末１００ａの供給状況を観察した。
【００４０】
さらに、上記の溶融処理を行い、処理粉末１００ｃを回収した後に、バーナ３０におけるキャリアガス（Ｎ_２ガス）の流量を１２０〜１４０ ｌ／ｍｉｎに上げ、原料粉末供給系統３１の配管中や、バーナ３０の内部に残存している原料粉末１００ａを噴出させ、燃料炎Ｆ中で溶融させた。そして、得られる処理粉末１００ｃを回収した。
その結果、無添加の試料１、添加量０．５重量％の試料５、およびステアリン酸アミドを添加した試料６において、バーナ３０における原料粉末１００ａの詰まりが確認された。
一方、添加量１．０％以上の試料２〜４の場合、詰まりがなかった。
【００４１】
加えて、上記の溶融処理で得られた処理粉末１００ｃの粒度分布を計測した。その結果を図６に示す。
図６に示すように、試料１〜６はいずれも、処理剤を添加しない試料１に較べ、粒度分布のピークが小さい側にシフトしている。また、処理剤が無添加の試料１や、添加量が１％以下の試料４、５においては、５μｍ以上の巨大粒子の存在が認められる。
また、ステアリン酸を１％添加した試料４と、ステアリン酸アミドを１％添加した試料６では、ステアリン酸アミドを添加した試料６のほうが粒度分布の集中度が高い。
【００４２】
図７は、処理剤を無添加の試料１（図７（ａ））と、ステアリン酸を２．０％添加した試料２（図７（ｂ））、ステアリン酸を１．５％添加した試料３（図７（ｃ））の組織写真である。
図７（ａ）に示したように、処理剤を無添加の試料１では、未溶融で球状化していない不定形粒子Ｙが多い。これに対し、図７（ｂ）に示したステアリン酸を２．０％添加した試料２では、図６に示したように、粒度分布が悪く、図７（ｂ）に示したように巨大粒子Ｚが認められるものの、未溶融の不定形粒子Ｙは少なく、溶融は行われている。ステアリン酸を１．５％添加した試料３では、図６に示したように粒度分布が揃っており、図７（ｃ）に示したように、巨大粒子Ｚが少なく、また未溶融の不定形粒子Ｙは少なく、溶融は行われている。
【００４３】
上記のような評価結果から、処理剤を添加することで原料粉末１００ａの流動性を向上させることができる。また、流動性、巨大粒子Ｚや不定形粒子Ｙの抑制といった面を総合すると、処理剤の添加量は、１．５重量％前後とするのが好ましい。
【００４４】
なお、上記実施の形態では、キャリアガスによって搬送される原料粉末１００ａに対し、所定角度で凝集解砕用ガスＧを噴射することのできるバーナ３０の具体的な構造を例示したが、同様の機能を果たすことができるのであれば、適宜他の構造を採用することが可能である。
また、球状粉末製造装置１０のさらに他の部分については、本発明の主旨を逸脱しない限り、上記実施の形態に示した構成を取捨選択したり、他の構成への変更、他の構成の追加等を適宜行うことが可能である。
【００４５】
【発明の効果】
以上説明したように、本発明によれば、処理剤を添加することで、原料粉末の流動性を向上させることができ、安定して良好な分散状態での原料粉末の供給を可能とし、また、凝集粒子を原因とする巨大粒子または未溶融粒子の発生を抑制することができる。
【図面の簡単な説明】
【図１】本実施の形態における粒状粉末製造装置の構成を示す断面図である（バーナは断面視していない）。
【図２】バーナの構成を示す断面図である。
【図３】（ａ）は図２のＡ−Ａ断面図、（ｂ）は図２のＢ−Ｂ断面図、（ｃ）は図２のＣ−Ｃ断面図である。
【図４】本発明の実施例を示すもので、処理剤の添加量と安息角の関係を示す図である。
【図５】同、処理剤の添加量と嵩密度との関係を示すものである。
【図６】同、処理剤の添加量と粒径分布の関係を示す図である。
【図７】同、試料１、２、３の組織写真である。
【符号の説明】
１０…球状粉末製造装置、２０…チャンバ、３０…バーナ、３１…原料粉末供給系統、６０…原料粉末供給管（流路）、６１…スリット、６２…外筒、６４…テーパ面、１００ａ…原料粉末（酸化物の粉末）、１００ｃ…処理粉末（球状粉末、球状酸化物粉末）、Ｆ…燃料炎、Ｇ…凝集解砕用ガス、θ…角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a spherical powder, a spherical oxide powder, and an oxide powder.
[0002]
[Prior art]
Conventionally, in the production of ceramic fillers such as paints and composite materials, in order to improve the dispersibility, filling properties, and fluidity of the powder, the powder particles must have characteristics such as a spherical shape and a smooth surface. Has been.
In order to spheroidize powder particles, there is a method of directly producing spherical particles using a synthesis method such as a sol-gel method or a spray pyrolysis method, but there are limitations on cost and production volume.
[0003]
Other methods for spheroidizing powder particles include melting them in a flame such as a combustion flame or thermal plasma or in a high-temperature electric furnace in a floating state and rounding them using the surface tension of the liquid. A method of obtaining a spherical powder (spherical powder) by melting a raw material powder using a combustion flame is generally used (see, for example, Patent Document 1).
Here, the flow of the process in the spherical powder manufacturing apparatus using the combustion flame will be described. First, the raw material powder supplied from the feeder is conveyed to the burner together with the carrier gas. The burner is supplied with oxygen from the oxygen supply means and combustion gas such as LPG from the combustion gas supply means, and the burner generates a combustion flame in a chamber provided in the lower part of the burner. The raw material powder melted and spheroidized in the combustion flame in the chamber is collected by a cyclone or a bag filter at the subsequent stage.
[0004]
[Patent Document 1]
JP 2003-40680 A (Claims)
[0005]
In the specification of the present application, the term “powder” refers to an aggregate of particles. If it is originally deemed appropriate to call the powder as an aggregate of particles, it is referred to as “powder”. When it is determined that the term “particle” as a constituent unit is appropriate, it is preferably called “particle”. However, since the basic unit is substantially the same, in the following explanation, in particular, “ Unless referred to as “particles”, it is basically referred to as “powder”.
[0006]
[Problems to be solved by the invention]
The particle size of the raw material powder is determined in consideration of the particle size of the spherical powder to be finally obtained. However, the raw material powder naturally aggregates while being accommodated in the feeder. In particular, when the average particle diameter of the raw material powder is fine, the degree of spontaneous aggregation is remarkable. When the naturally agglomerated raw material powder is supplied to the burner as it is and melt-processed, huge particles having a particle size several times the originally intended particle size are generated or a combustion flame mainly due to the generation of aggregates Unmelted particles are generated due to a local decrease in internal temperature.
Moreover, when the particle size of raw material powder becomes fine, fluidity | liquidity will deteriorate rapidly in the supply system in a spherical powder manufacturing apparatus. Poor flowability of the powder can cause bridging in the feeder hopper and stop feeding. In addition, the raw material powder is clogged in the supply pipe to the burner and the burner, causing a problem that the supply is stopped and the pulsation becomes severe. When pulsation occurs, a large amount of raw material powder enters the flame all at once, causing problems such as being mixed into the product as it is without being melted or being melted as a large lump resulting in the generation of huge particles.
As described above, in the production of fine spherical powder, there is a problem of ensuring the fluidity of the raw material powder and supplying the raw material powder in a stable and stable state.
[0007]
The present invention has been made on the basis of such a technical problem, and it is possible to supply raw material powder in a stable and good dispersed state, and to suppress the generation of giant particles or unmelted particles caused by aggregated particles. It aims at providing the manufacturing method etc. of powder.
[0008]
[Means for Solving the Problems]
Conventionally, in the spherical powder manufacturing apparatus as described above, a spherical powder having an average particle diameter of 1 to 10 μm is manufactured. However, a spherical powder is manufactured under more severe conditions such as an average particle diameter of 1 to 2 μm and a maximum particle diameter of 5 μm. When trying to do so, the problems as described above became very remarkable, and there was a problem in the stable production of spherical powder.
Therefore, when the present inventors diligently studied, in the process, attention was paid to waxes such as higher fatty acids such as stearic acid or derivatives thereof, higher hydrocarbons and higher alcohols. They came to think that the raw material powder could be surface treated with waxes to prevent the raw material powder from agglomerating.
[0009]
A method for producing the spherical powder of the present invention made therewith includes a surface treatment step of surface-treating a raw material powder with a treatment agent comprising at least one of a higher fatty acid or a derivative thereof, a higher hydrocarbon, and a higher alcohol, and a surface treatment. A spherical powder generation process in which the raw material powder is put into a combustion flame generated in a burner, melted in the combustion flame to be spheroidized, and further, the raw material powder moves out of the combustion flame and solidifies to obtain a spherical powder And. At this time, in the surface treatment step, the raw material powder and the treatment agent are heated to a predetermined temperature and then stirred to surface-treat the raw material powder. Further, the predetermined temperature is preferably set to at least the melting point of the processing agent, and more preferably set to a temperature range in which the processing agent burns and scatters or evaporates and vaporizes.
In addition, it is also effective to repeat the heating / stirring process again after heating / stirring. In that case, it is preferable to cool it once to below the melting point of the treating agent before heating again. Thereby, a processing agent can be made to adhere evenly to the surface of raw material powder.
As such a treatment agent, it is preferable to use any of stearic acid, stearamide, and hardened castor oil.
The amount of treatment agent added to the raw material powder is preferably 0.1 to 5.0% by weight.
[0010]
By the way, in the spherical powder generating step, the raw material powder introduced into the combustion flame generated by the burner can be dispersed by a dispersing means for dispersing the raw material powder when it is in an agglomerated state.
As such a dispersing means, various means can be used such as a structure in which the raw material powder collides with the raw material powder, and in particular, for supplying the raw material powder into the combustion flame. A configuration in which gas is injected at a predetermined angle with respect to the flow path is preferable.
[0011]
According to the method for producing a spherical powder according to any one of claims 1 to 5 as described above, the average particle size is 5 μm or less, the maximum particle size is 10 μm or less, more desirably the average particle size is 3 μm or less, and the maximum particle size is Can produce a spherical oxide powder having a thickness of 5 μm or less.
In this case, the raw material powder is used to obtain a spherical powder by melting in a combustion flame, and the surface of the oxide powder is prevented from agglomerating with higher fatty acids or derivatives thereof, higher hydrocarbons, higher It is preferable to use an oxide powder which is surface-treated with a treatment agent comprising at least one of alcohols and has an average particle size of 5 μm or less.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
In the present embodiment, after adding a treatment agent for improving the fluidity of the raw material powder, the raw material powder is supplied to the spherical powder manufacturing apparatus and put into the combustion flame of the burner. Get. Moreover, it is set as the structure which provides the mechanism for crushing aggregation of raw material powder in the burner which produces a combustion flame.
[0013]
As the treating agent to be added to the raw material powder, waxes such as higher fatty acids or derivatives thereof, higher hydrocarbons, higher alcohols and the like used as dispersing agents and surface treatment materials are suitable. More specifically, stearic acid, stearamide, and hardened castor oil are suitable as the waxes.
Since these waxes do not contain a metal element, the composition of the raw material powder does not deviate even after a spheroidizing treatment described in detail later.
Here, the amount of the treatment agent added to the raw material powder is preferably 0.1 to 8.0% by weight, and more preferably 1.0 to 5.0% by weight.
[0014]
After such a treatment agent is mixed in the raw material powder, it is put in an almost sealed container (in order to suppress the dispersion of the treatment agent), and then put into a heating furnace (such as a drying furnace) heated to a temperature higher than the melting point of the treatment agent. Is preferred.
In this way, by introducing the raw material powder and the treatment agent into the heating furnace, it is possible to melt the treatment agent and further evaporate it to vaporize it, so that it adheres thinly and uniformly to the surface of the raw material powder. Can be made.
Then, after the processing agent and the raw material powder are put into the heating furnace, after maintaining the temperature for a predetermined time, they are taken out from the heating furnace, and the raw material powder and the molten processing agent are stirred.
The steps of heating to stirring in the heating furnace are preferably repeated a plurality of times as necessary.
[0015]
FIG. 1 is a diagram for explaining the configuration of a spherical powder production apparatus for producing a spherical powder using the raw material powder to which the treatment agent has been added as described above as a raw material.
As shown in FIG. 1, the spherical powder manufacturing apparatus 10 includes a chamber 20 and a burner 30 provided on the upper portion of the chamber 20. At the lower part of the chamber 20, a processing powder recovery means composed of a recovery container 41 and a cyclone 42 and a gas discharge means 50 are provided.
[0016]
The chamber 20 is formed of, for example, SUS, alumina, or the like having high heat resistance, and has a cylindrical shape having an axis in the vertical direction. The chamber 20 is formed continuously with a cylindrical wall portion 20a having the same inner diameter and a lower end portion thereof. The taper portion 20b has an inner diameter that gradually decreases as it goes to.
The upper portion of the chamber 20 is open, and a lid 21 is provided in the opening. The lid 21 includes a burner 30 at a position facing the center of the chamber 20.
[0017]
Although the detailed configuration of the burner 30 itself will be described later, the burner 30 has a multi-tube structure, and a raw material powder supply system 31 for supplying a raw material powder (oxide powder) 100a to each region and oxygen as a combustion supporting gas. An oxygen supply system 32 that supplies gas and a combustion gas supply system 33 that supplies combustion gas are connected.
[0018]
As the raw material powder 100a supplied from the raw material powder supply system 31, for example, an oxide composition used as a dielectric material or a magnetic material can be used. Examples of the dielectric material include barium titanate-based, lead titanate-based, calcium titanate, strontium titanate-based, titanium dioxide-based, and barium-neodi-titanium-based (BNT-based) oxides. Examples of the magnetic material include Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg—Zn ferrite, Ni—Cu—Zn ferrite, and the like. Further, iron oxide such as Fe ₂ O ₃ or Fe ₃ O ₄ can be used as the raw material powder 100a.
The particle size of the raw material powder 100a may be appropriately determined according to the particle size of the spherical powder to be finally obtained. For example, when it is desired to finally obtain a spherical powder having an average particle diameter of 1 to 2 μm, a raw material powder 100a having a diameter of 1 to 2 μm can be used.
[0019]
Supply of the raw material powder 100a is performed using carrier gas, such as air, oxidizing gas, an inert gas. As the oxidizing gas, a gas having an oxygen concentration of 20% or more can be used. As the inert gas, N ₂ gas, He gas, Ne gas, Ar gas, Kr gas, Xe gas, Rn gas, or the like can be used.
[0020]
Such a burner 30 ignites the oxygen supplied from the oxygen supply system 32 and the combustion gas supplied from the combustion gas supply system 33 toward the lower side of the chamber 20, thereby igniting the chamber. The combustion flame F is produced | generated to the upper part of 20 center part.
The combustion gas for obtaining the combustion flame F is not particularly limited. Known combustion gases such as LPG, hydrogen, and acetylene can be used.
[0021]
The raw material powder 100a is put into the combustion flame F, stays in the combustion flame F for a predetermined time while falling down naturally, is melted by the heat of the combustion flame F, or is subjected to chemical / physical modification, and the inside of the chamber 20 Fall. At this time, the raw material powder 100a is solidified as its temperature drops while dropping in the chamber 20.
The raw material powder 100a that has passed through the combustion flame F in this way becomes the treated powder 100b. The chemical / physical modification means changing the material form, purity, particle size, particle structure, shape or surface property of the raw material powder 100a.
[0022]
A recovery container 41 is connected to the lower end of the tapered portion 20b of the chamber 20 where the above processing is performed. A cyclone 42 is connected to the side surface of the collection container 41.
The processing powder 100b dropped in the chamber 20 is deposited on the bottom of the collection container 41, and a part of the processing powder 100b is sent to the cyclone 42 together with the gas.
In the cyclone 42, the gas (gas) mixed with the processing powder 100 b and the solid (the processing powder 100 b) are separated vertically. The treated powder 100 b separated from the gas is deposited on the bottom of the cyclone 42.
By collecting the processing powder 100b deposited on the bottoms of the recovery container 41 and the cyclone 42, a spherical processing powder (spherical powder, spherical oxide powder) 100c can be obtained.
A filter device 52 such as a bag filter is connected to the upper part of the cyclone 42, and the processing powder 100 c remaining in the gas discharged from the cyclone 42 is collected by the filter main body 52 a, and only the gas is passed through the blower 53. Thus, the gas is discharged from the discharge pipe 54.
[0023]
Next, the burner 30 will be described in detail with reference to FIGS. 2 and 3.
Here, FIG. 2 is a sectional view of the burner 30. 3A is a sectional view taken along the line AA in FIG. 2, FIG. 3B is a sectional view taken along the line BB in FIG. 2, and FIG. 3C is a sectional view taken along the line CC in FIG. Hereinafter, the left side of the paper surface of FIG. 2 is referred to as the upstream side of the burner 30 and the right side of the paper surface is referred to as the downstream side of the burner 30 based on the flow of the raw material powder 100a.
As shown in FIG. 2 and FIG. 3, the burner 30 has a raw material powder supply pipe (flow channel) 60 disposed concentrically with the outer case 80 in a substantially cylindrical outer case 80, A predetermined number of oxygen supply pipes 70 are arranged so as to surround the outer periphery of the powder supply pipe 60.
[0024]
A chamber 33 a connected to the combustion gas supply system 33 and a chamber 32 a connected to the oxygen supply system 32 are provided on the upstream side of the outer case 80. The oxygen supply pipe 70 passes through the chamber 33a and is provided so that an end thereof is opened in the chamber 32a connected to the oxygen supply system 32.
The oxygen as the combustion support gas supplied from the oxygen supply system 32 is supplied into the chamber 32 a, flows into the oxygen supply pipe 70, and is ejected from the opening on the downstream side of the burner 30. Combustion gas such as LPG supplied from the combustion gas supply system 33 is supplied to the chamber 33a, passes through the space inside the outer case 80 and outside the oxygen supply pipe 70, and is an opening on the downstream side of the burner 30. Erupts from.
Thereby, on the downstream side of the burner 30, a combustion gas such as LPG and a combustion supporting gas such as oxygen are ejected, and a combustion flame F is generated by igniting the combustion gas.
[0025]
The raw material powder supply pipe 60 passes through the chambers 32 a and 33 a, the upstream side thereof is connected to a feeder (not shown), and the downstream side is opened on the downstream side of the burner 30. The raw material powder 100a conveyed by the carrier gas from the feeder passes through the raw material powder supply pipe 60 and is supplied into the combustion flame F from the opening on the downstream side of the burner 30.
[0026]
The raw material powder supply pipe 60 is provided with a mechanism for crushing the aggregation of the raw material powder 100a. Therefore, slits 61 (or a plurality of slits formed at intervals in the circumferential direction) that are continuous in the circumferential direction are formed in the intermediate portion of the raw material powder supply pipe 60.
The raw material powder supply pipe 60 is concentrically provided in an outer cylinder 62 having an inner diameter larger than the outer diameter of the raw material powder supply pipe 60 by a predetermined dimension. Here, a cylindrical sleeve 63 is provided in the gap between the raw material powder supply pipe 60 and the outer cylinder 62 on the downstream side of the slit 61 of the raw material powder supply pipe 60, and is supported by the sleeve 63. The raw material powder supply pipe 60 is located at the center of the outer cylinder 62.
[0027]
Similarly to the raw material powder supply pipe 60, the outer cylinder 62 passes through the chambers 32a and 33a, and is used for agglomeration in the gap between the outer cylinder 62 and the raw material powder supply pipe 60 at the upstream end thereof. Gas G is sent in. The dimension L of the gap between the outer cylinder 62 and the raw material powder supply pipe 60 can be set to 0.5 to 10 mm, for example. By appropriately setting the dimension L, it is possible to control the flow rate and speed of the coagulation / disintegration gas G.
Here, as the coagulation / disintegration gas G, the same carrier gas as described above, that is, air, oxidizing gas, inert gas, or the like can be used. Further, LPG, hydrogen, acetylene, etc. mentioned as the combustion gas may be used as the coagulation / disintegration gas G.
[0028]
On the downstream side of the slit 61, the end surface 61 a of the slit 61 and the end surface 63 a of the sleeve 63 are continuous to form a tapered surface 64 that intersects the axis of the raw material powder supply pipe 60 at a predetermined angle θ. Further, on the upstream side of the slit 61, the end surface 61 b of the slit 61 is also formed so as to substantially intersect the axis of the raw material powder supply pipe 60 at a predetermined angle θ.
[0029]
Thereby, the coagulation / disintegration gas G fed into the gap between the outer cylinder 62 and the raw material powder supply pipe 60 flows into the raw material powder supply pipe 60 from the slit 61 portion. At this time, due to the tapered surface 64 formed so as to intersect the axis of the raw material powder supply pipe 60 at a predetermined angle θ, the coagulation / disintegration gas G is transferred into the carrier gas and the raw material powder 100a in the raw material powder supply pipe 60. To flow into the raw material powder supply pipe 60 so as to intersect at a predetermined angle. Thereby, before the raw material powder 100a is supplied into the combustion flame F, the coagulation / disintegration gas G is injected to the raw material powder 100a being conveyed, and the aggregation of the raw material powder 100a is crushed.
Here, the coagulation / pulverization gas G is desirably injected at an angle of 5 to 85 ° with respect to the axis of the raw material powder supply pipe 60. When the angle is less than 5 °, the impact on the raw material powder 100a given by the coagulation / pulverization gas G is small, and it is difficult to sufficiently pulverize the aggregated particles composed of the raw material powder 100a. This is because if the spray angle exceeds 85 °, the raw material powder 100a tends to adhere to the inner wall of the raw material powder supply pipe 60 and the tapered surface 64.
In order to set the spray angle of the coagulation / disintegration gas G to 5 to 85 °, the angle θ of the tapered surface 64 intersecting the axis of the raw material powder supply pipe 60 may be set to 5 to 85 °.
Further, a more preferable injection angle of the coagulation / disintegration gas G is 15 to 75 °, and more preferably 20 to 60 °.
[0030]
Further, the size of the slit 61 may be appropriately set according to the size of the raw material powder supply pipe 60 and the processing amount of the raw material powder 100a. The position of the slit 61 in the axial direction is determined in consideration of the distance to the combustion flame F. Specifically, the slit 61 is formed in the raw material powder supply pipe 60 so that the distance to the combustion flame F is in the range of 10 to 300 mm. When the distance from the slit 61 to the combustion flame F is less than 10 mm, it becomes difficult to supply the raw material powder 100a to the combustion flame F after reliably crushing the aggregated particles. On the other hand, if the distance from the slit 61 to the combustion flame F exceeds 300 mm, the raw material powder 100a that has been crushed once may be re-agglomerated while being conveyed, which is not preferable.
[0031]
In the spherical powder manufacturing apparatus 10 having such a configuration, the raw material powder 100a to which the processing agent is added in the preceding stage is conveyed through the raw material powder supply pipe 60 by a carrier gas from a feeder (not shown) and burned from the tip of the burner 30. Put in flame F. As a result, the raw material powder 100a is melted, and further moved out of the combustion flame F to be cooled and solidified to be subjected to spheroidization treatment, and finally, the treated powder 100c can be obtained.
The obtained treated powder 100c has excellent characteristics according to the purpose of treatment, such as fine particles with good crystallinity, single crystal particles, and powder composed of spherical particles (particles with high sphericity). By using such a processed powder 100c in combination with or mixing with other materials, it is possible to obtain products having excellent characteristics and materials and parts having special structures and functions. Specifically, a high frequency filter or the like can be obtained.
[0032]
As described above, the processing agent for preventing aggregation is added to the raw material powder 100a supplied to the spherical powder manufacturing apparatus 10. As a result, compared to the prior art, the raw material powder 100a is less likely to spontaneously agglomerate while being supplied in a feeder (not shown) to be supplied to the burner 30, and is less likely to agglomerate during conveyance. In addition, by heating the raw material powder 100a and the processing agent in a heating furnace so that the processing agent is at least melted and vaporized, the processing agent can be thinly and evenly attached to the surface of the raw material powder 100a, that is, evenly distributed. As a result, the effect of preventing aggregation is further ensured.
Further, even when the raw material powder 100a is naturally agglomerated while being accommodated in the feeder, the raw material powder is injected from the outer peripheral side of the raw material powder supply pipe 60 to the inside thereof by injecting the agglomeration gas G Aggregation of 100a can be crushed.
Thereby, agglomeration is crushed, the raw material powder 100a can be introduced into the combustion flame F in a well dispersed state, and generation of giant particles and unmelted particles can be suppressed.
[0033]
As a result, compared to the configuration of the conventional method, the generation of huge particles and the generation of unmelted particles can be greatly suppressed, and the quality of the produced spherical powder can be stabilized and improved. If huge particles are generated, the temperature of the combustion flame F is lowered and the temperature distribution becomes non-uniform, which makes it difficult to reliably melt the raw material powder 100a, and the generation of unmelted particles increases accordingly. Become. Further, when the generation rate of giant particles increases, it becomes difficult to establish a correspondence between the particle size of the raw material powder 100a and the particle size of the spherical powder, and it becomes difficult to control the particle size distribution of the spherical powder. On the other hand, according to the configuration in the present embodiment, it is possible to prevent the aggregation of the raw material powder 100a by adding the treatment agent to the raw material powder 100a, and even if the raw material powder 100a is aggregated, the raw material powder In the stage where 100a is supplied into the combustion flame F and melted, the agglomeration has already been crushed. As a result, the correspondence between the particle size of the raw material powder 100a and the particle size of the spherical powder can be taken, and the particle size distribution of the spherical powder can be easily controlled. Thereby, the spherical powder which has a desired particle size distribution can be obtained reliably.
[0034]
【Example】
Here, the results of the evaluation of the anti-aggregation effect due to the addition of the treatment agent are shown.
Raw material: Barium titanate was used as the raw material.
Treatment agent: Stearic acid or stearamide was used as the treatment agent.
In Samples 1 to 6, the raw materials and the processing agent as described above were mixed at the following ratio.
Sample 1: 800 g of raw material powder, 0% by weight of treatment agent
Sample 2: 800 g of raw material powder, 2.0% by weight of stearic acid
Sample 3: 800 g of raw material powder, 1.5% by weight of stearic acid
Sample 4: 800 g of raw material powder, 1.0% by weight of stearic acid
Sample 5: Raw material powder 800 g, stearic acid 0.5 wt%
Sample 6: 800 g of raw material powder, 1.0% by weight of stearamide
Here, the amount of the treating agent is based on the amount of the raw material.
[0035]
The raw materials and treatment agent thus obtained were put into a heating furnace heated to 100 ° C., maintained at the temperature for 10 minutes, and then taken out from the heating furnace and stirred. This heating to stirring was repeated 3 times in total, and after cooling, the mixture was passed through a sieve having an opening of 74 μm, and thereafter, the following fluidity evaluation was performed.
[0036]
For evaluation of fluidity, a 500 μm mesh is passed through and each of samples 1 to 6 is dropped onto a cell (container) of about 20 ml positioned below, whereby a peak of raw material powder 100a having a vertex is placed on the cell. The angle of repose of the formed mountain (the angle of the slope of the mountain with respect to the cell surface) was measured.
Furthermore, after removing the powder at the peak protruding above the cell by scraping along the top surface of the cell with a spatula, the weight of the powder filled in the cell is measured, and the bulk density is determined based on the cell capacity. Was calculated.
Table 1 and FIGS. 4 and 5 show the results.
[0037]
[Table 1]

[0038]
As shown in Table 1, FIG. 4 and FIG. 5, in Samples 2 to 5, the angle of repose is slightly lower compared to Sample 1 with no treatment agent added, and the more the amount of stearic acid added, The angle of repose tends to decrease. On the other hand, the bulk density in samples 2 to 5 is almost constant regardless of the amount of stearic acid added.
Thereby, it can be said that the fluidity of the raw material powder 100a is increased by the addition of stearic acid.
[0039]
Subsequently, the obtained raw material powder 100a (samples 1 to 12) was put into a feeder (not shown) of the spherical powder production apparatus 10 and spheroidized by the combustion flame F generated in the burner 30.
At this time, in the burner 30, oxygen is supplied from the oxygen supply system 32 at a flow rate of 75 l (liter) / min, and LPG is supplied from the combustion gas supply system 33 at a flow rate of 15 l / min to generate the combustion flame F. In the raw material powder supply system 31, the raw material powder 100a is supplied into the combustion flame F and melted by driving the feeder at 1.20 rpm while supplying N ₂ gas as a carrier gas at a flow rate of 70 l / min. I did it.
And the supply condition of the raw material powder 100a at the time of melting was observed.
[0040]
Furthermore, after performing the above-described melting treatment and collecting the treated powder 100c, the flow rate of the carrier gas (N ₂ gas) in the burner 30 is increased to 120 to 140 l / min, and in the piping of the raw material powder supply system 31, The raw material powder 100a remaining inside 30 was ejected and melted in the fuel flame F. And the processing powder 100c obtained was collect | recovered.
As a result, clogging of the raw material powder 100a in the burner 30 was confirmed in the non-added sample 1, the sample 5 having an addition amount of 0.5% by weight, and the sample 6 to which stearamide was added.
On the other hand, in the case of Samples 2 to 4 with an addition amount of 1.0% or more, there was no clogging.
[0041]
In addition, the particle size distribution of the treated powder 100c obtained by the above melting treatment was measured. The result is shown in FIG.
As shown in FIG. 6, all of Samples 1 to 6 are shifted to a smaller particle size distribution peak compared to Sample 1 to which no treatment agent is added. In Sample 1 to which no treatment agent was added and Samples 4 and 5 having an addition amount of 1% or less, the presence of giant particles of 5 μm or more was observed.
Also, in the sample 4 to which 1% of stearic acid is added and the sample 6 to which 1% of stearic acid amide is added, the sample 6 to which stearic acid amide is added has a higher degree of concentration of the particle size distribution.
[0042]
FIG. 7 shows sample 1 (FIG. 7 (a)) to which no treatment agent was added, sample 2 to which 2.0% of stearic acid was added (FIG. 7 (b)), and sample to which 1.5% of stearic acid was added. It is a structure photograph of 3 (Drawing 7 (c)).
As shown in FIG. 7A, the sample 1 to which no treatment agent is added contains a large number of amorphous particles Y that are unmelted and not spheroidized. On the other hand, in the sample 2 to which 2.0% of stearic acid shown in FIG. 7 (b) is added, the particle size distribution is poor as shown in FIG. 6, and the giant particles are shown in FIG. 7 (b). Although Z is observed, unmelted amorphous particles Y are few and melting is performed. In sample 3 to which 1.5% of stearic acid was added, the particle size distribution was uniform as shown in FIG. 6, and there were few large particles Z as shown in FIG. The particles Y are few and melting is performed.
[0043]
From the evaluation results as described above, the fluidity of the raw material powder 100a can be improved by adding the treatment agent. Further, considering the aspects of fluidity, suppression of the giant particles Z and the irregular particles Y, the addition amount of the treatment agent is preferably about 1.5% by weight.
[0044]
In the above embodiment, the specific structure of the burner 30 capable of injecting the coagulation / disintegration gas G at a predetermined angle with respect to the raw material powder 100a conveyed by the carrier gas is exemplified. As long as the above can be achieved, other structures can be employed as appropriate.
Further, for other parts of the spherical powder manufacturing apparatus 10, unless otherwise departing from the gist of the present invention, the configuration shown in the above embodiment is selected, changed to another configuration, or added to another configuration. Etc. can be appropriately performed.
[0045]
【The invention's effect】
As described above, according to the present invention, by adding the treatment agent, the fluidity of the raw material powder can be improved, and the raw material powder can be stably supplied in a good dispersion state. The generation of giant particles or unmelted particles due to aggregated particles can be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a granular powder production apparatus in the present embodiment (a burner is not seen in cross section).
FIG. 2 is a cross-sectional view showing a configuration of a burner.
3A is a cross-sectional view taken along line AA in FIG. 2, FIG. 3B is a cross-sectional view taken along line BB in FIG. 2, and FIG. 3C is a cross-sectional view taken along line CC in FIG.
FIG. 4, showing an example of the present invention, is a diagram showing the relationship between the amount of treatment agent added and the angle of repose.
FIG. 5 shows the relationship between the amount of treatment agent added and the bulk density.
FIG. 6 is a graph showing the relationship between the amount of treatment agent added and the particle size distribution.
FIG. 7 is a structure photograph of Samples 1, 2, and 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Spherical powder manufacturing apparatus, 20 ... Chamber, 30 ... Burner, 31 ... Raw material powder supply system, 60 ... Raw material powder supply pipe (flow path), 61 ... Slit, 62 ... Outer cylinder, 64 ... Tapered surface, 100a ... Raw material Powder (oxide powder), 100c ... treated powder (spherical powder, spherical oxide powder), F ... fuel flame, G ... coagulation gas, θ ... angle

Claims (7)

A surface treatment step of surface-treating the raw material powder by stirring the raw material powder and a treatment agent comprising at least one of higher fatty acids or derivatives thereof, higher hydrocarbons, and higher alcohols after heating to a predetermined temperature. When,
Spherical powder generation that obtains a spherical powder by putting the raw material powder that has been surface-treated into a combustion flame generated in a burner and melting it, and then solidifying it by moving the raw material powder out of the combustion flame Process,
A method for producing a spherical powder, comprising: The method for producing a spherical powder according to claim 1, wherein the treatment agent is any one of stearic acid, stearamide, and hardened castor oil. The method for producing a spherical powder according to claim 1 or 2, wherein the amount of the treatment agent added to the raw material powder is 0.1 to 8.0 wt%. In the spherical powder generating step, the raw material powder introduced into the combustion flame generated in the burner is dispersed by a dispersing means for dispersing the raw material powder when the raw material powder is in an agglomerated state. The manufacturing method of the spherical powder in any one of Claim 1 to 3. The gas is injected at a predetermined angle to a flow path for supplying the raw material powder into the combustion flame in order to disperse the raw material powder when it is in an agglomerated state. A method for producing the spherical powder as described. A spherical oxide powder produced by the method for producing a spherical powder according to claim 1, having an average particle size of 5 μm or less and a maximum particle size of 10 μm or less. An oxide powder for obtaining a spherical powder by melting in a combustion flame,
The surface of the oxide powder is surface-treated with a treatment agent comprising at least one of higher fatty acids or derivatives thereof, higher hydrocarbons, and higher alcohols to prevent aggregation, and the average particle size is 5 μm or less. An oxide powder characterized by that.

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