JPH05310425A - Production of metal oxide fine particle - Google Patents
Production of metal oxide fine particleInfo
- Publication number
- JPH05310425A JPH05310425A JP11881092A JP11881092A JPH05310425A JP H05310425 A JPH05310425 A JP H05310425A JP 11881092 A JP11881092 A JP 11881092A JP 11881092 A JP11881092 A JP 11881092A JP H05310425 A JPH05310425 A JP H05310425A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- fine particles
- metal oxide
- metal salt
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/18—Methods for preparing oxides or hydroxides in general by thermal decomposition of compounds, e.g. of salts or hydroxides
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、金属酸化物微粒子の製
造方法、更に詳しくは、金属酸化物球状微粒子の製造方
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing metal oxide fine particles, and more particularly to a method for producing spherical metal oxide particles.
【0002】[0002]
【従来の技術】一般に、金属酸化物微粒子は、光導電
性、圧電性、蛍光性、触媒効果等の性能を利用して様々
な工業分野で利用されており、その中でも、酸化亜鉛微
粒子は、種々の工業製品、医薬品、ゴムの加硫促進剤、
触媒、バリスター(可変抵抗器)、塗料等に用いられ、最
近では紫外線遮蔽材としてUV化粧品にも用いられてい
る。2. Description of the Related Art Generally, metal oxide fine particles are used in various industrial fields by utilizing their properties such as photoconductivity, piezoelectricity, fluorescence, and catalytic effect. Among them, zinc oxide fine particles are Various industrial products, pharmaceuticals, vulcanization accelerators for rubber,
It is used in catalysts, varistors (variable resistors), paints, etc., and is recently used in UV cosmetics as an ultraviolet shielding material.
【0003】また、酸化チタン微粒子も、白色顔料、磁
気原料、研磨剤、医薬品等に用いられ、最近では酸化亜
鉛微粒子と同様に紫外線遮蔽剤として用いられ、また、
その他の金属酸化物微粒子も同様に種々の用途に利用さ
れている。Further, fine particles of titanium oxide are also used for white pigments, magnetic raw materials, abrasives, pharmaceuticals, etc., and recently, they are also used as an ultraviolet shielding agent like fine particles of zinc oxide.
Other metal oxide fine particles are also used for various purposes.
【0004】以上のように、金属酸化物微粒子は、その
工業的価値が極めて大きく、その機能を最大限に発現さ
せるためには微粒子化が重要である。すなわち、微粒子
化することにより、比表面積が増大したり、微粒子を構
成する全分子数中に占める微粒子表面に位置する分子数
の割合が大きくなるために微粒子の表面エネルギーが増
大するため、その機能が極めて大きく発現される。ま
た、均一な形状を利用して機能の増大を図る場合には、
均一な球状粒子化が重要となる。As described above, the metal oxide fine particles have an extremely great industrial value, and it is important to make them fine in order to maximize their functions. That is, by making the particles finer, the specific surface area increases, and the ratio of the number of molecules located on the surface of the fine particles in the total number of molecules forming the fine particles increases, so that the surface energy of the fine particles increases, so Is extremely greatly expressed. If you want to increase the function by using a uniform shape,
Uniform spherical particles are important.
【0005】前述の極めて重要な工業的価値を有する金
属酸化物微粒子の製造方法には、大きく分けて、液相法
と気相法がある。The above-mentioned methods for producing metal oxide fine particles having extremely important industrial value are roughly classified into a liquid phase method and a gas phase method.
【0006】液相法では、例えば酸化亜鉛微粒子の製造
では、それらの金属アルコキシドを加水分解して酸化亜
鉛超微粒子を得る方法(特開平2−59425号公報)が
ある。また、一般的には、古くから、金属塩に酸・アル
カリの溶液を加えて液相内反応を起こすことにより、所
望の金属酸化物を得る方法がある。In the liquid phase method, for example, in the production of zinc oxide fine particles, there is a method of hydrolyzing the metal alkoxide to obtain zinc oxide ultrafine particles (Japanese Patent Laid-Open No. 2-59425). In general, there has been a method for obtaining a desired metal oxide by adding an acid / alkali solution to a metal salt and causing a reaction in a liquid phase.
【0007】気相法では、一般に金属を蒸気化し、その
蒸気と酸素を含有するガスとを混合して金属酸化物微粒
子を得る方法(例えば、酸化亜鉛微粒子の製造では、特
開平1−286919号公報および特開平2−2083
69号公報)がある。In the gas phase method, a metal is generally vaporized, and the vapor and a gas containing oxygen are mixed to obtain metal oxide fine particles (for example, in the production of zinc oxide fine particles, JP-A-1-286919). Japanese Patent Laid-Open No. 2083/1990
No. 69).
【0008】前記の液相法と気相法以外に、噴霧熱分解
法があり、これは金属の無機酸塩または有機酸塩を含む
水溶液あるいは有機溶媒溶液を霧化し、この霧状液体粒
子を加熱炉に搬送して、熱分解反応により酸化物系微粒
子を得る方法(例えば、酸化物系超電導体の製造では、
特開平2−196023号公報)がある。In addition to the liquid phase method and the gas phase method, there is a spray pyrolysis method, which atomizes an aqueous solution or an organic solvent solution containing an inorganic acid salt or an organic acid salt of a metal, and atomizes the atomized liquid particles. A method of obtaining oxide-based fine particles by carrying out a thermal decomposition reaction by transporting to a heating furnace (for example, in the production of oxide-based superconductors,
JP-A-2-196023).
【0009】以上の従来技術を考えた場合、液相法で
は、その出発原料を選定するのに、所望とする金属酸化
物微粒子について、その金属を含む金属アルコキシドを
合成するのには限界があり、換言すれば金属アルコキシ
ド化できない金属もあり、広範な金属酸化物微粒子を製
造できるとは言い難い。また、古くから行われている金
属塩を用いる方法では、出発原料の選定にはほとんど制
限がないものの、それらを液相内で反応させるためには
各種の酸・アルカリ溶液を経験的に選んで合成しなけら
ばならず、その合成過程を決定するのが複雑で長時間を
要する。そして、これらの液相法による製造プロセスに
ついては、バッチ式が基本となるため、自動化が困難
で、しかも生成微粒子は固液混相の状態で得られ、製品
として得るには必ず濾過、乾燥の工程が加わり、製造プ
ロセス全体が複雑となり、低コスト化が困難である。In consideration of the above-mentioned conventional techniques, the liquid phase method has a limit in selecting the starting material thereof and synthesizing the metal alkoxide containing the metal with respect to the desired metal oxide fine particles. In other words, some metals cannot be converted into metal alkoxides, and it is difficult to say that a wide range of metal oxide fine particles can be produced. Moreover, in the method using metal salts, which has been used for a long time, there are almost no restrictions on the selection of starting materials, but in order to react them in the liquid phase, various acid / alkali solutions must be empirically selected. It has to be synthesized, and determining the synthesis process is complicated and takes a long time. And since the manufacturing process by these liquid phase methods is basically a batch system, it is difficult to automate, and the fine particles produced are obtained in a solid-liquid mixed phase state. Therefore, the whole manufacturing process becomes complicated and it is difficult to reduce the cost.
【0010】一方、気相法では、原料に純度の高い金属
を用いることが製品の純度を高めるために必要である
が、その分コスト高となる。また、一般に金属の融点は
高いので、金属を蒸気化するためにはかなり高温にする
必要があり、装置の設計においても高温を維持できるよ
うな材質を選定しなければならず、製造プロセスの安全
性面からも好ましくない。On the other hand, in the vapor phase method, it is necessary to use a high-purity metal as a raw material in order to improve the purity of the product, but the cost is increased accordingly. In addition, since the melting point of metal is generally high, it is necessary to raise the temperature to a considerably high temperature in order to vaporize the metal, and it is necessary to select a material that can maintain the high temperature even in the design of the equipment, and the safety of the manufacturing process. It is not preferable in terms of sex.
【0011】また、前記噴霧熱分解法では、気固混相の
状態で得られた酸化物系微粒子を回収するのに、霧状原
料液体の粒子を放射線照射等の手段により荷電した後、
加熱炉に搬送して熱分解反応により酸化物系帯電微粒子
とし、この帯電微粒子を所定の加温された基体上に堆積
させる方法を用いている。しかし、その方法では、荷電
装置内に液滴が入るため、運転時間の経過につれて電荷
発生部が液濡れ状態となり、荷電装置の動作不良が起こ
ったり、また基体を加熱炉内に設置するため、その基体
の大きさが制限され、かつ装置系が複雑となる。従っ
て、連続運転が困難で、大量生産に適さない。In the spray pyrolysis method, in order to recover the oxide-based fine particles obtained in the gas-solid mixed phase, after the particles of the atomized raw material liquid are charged by means such as radiation irradiation,
A method is used in which the particles are conveyed to a heating furnace to be charged into oxide-based charged fine particles by a thermal decomposition reaction, and the charged fine particles are deposited on a substrate heated at a predetermined temperature. However, in that method, since the liquid droplets enter the charging device, the charge generation section becomes wet with the passage of operating time, malfunction of the charging device occurs, and the substrate is installed in the heating furnace. The size of the substrate is limited, and the device system becomes complicated. Therefore, continuous operation is difficult and not suitable for mass production.
【0012】また、前記噴霧熱分解法による微粒子製造
では、加熱炉内の温度分布についての規定がなく、炉内
温度分布が及ぼす生成微粒子の形状への影響は明らかで
ない。したがって、急峻な炉内温度分布を用いて微粒子
製造を行った場合、破砕粒子が多く生成するため、均一
形状とならずに粒度分布の極めて広い粗雑な微粒子とな
る。In the production of fine particles by the spray pyrolysis method, there is no regulation on the temperature distribution in the heating furnace, and the influence of the temperature distribution in the furnace on the shape of the produced fine particles is not clear. Therefore, when fine particles are produced by using a sharp temperature distribution in the furnace, many crushed particles are generated, and coarse particles having an extremely wide particle size distribution do not form a uniform shape.
【0013】[0013]
【発明が解決しようとする課題】従って、本発明は、管
長方向での温度分布を規定した簡便なプロセスを用いる
ことにより、広範な種類の均一な金属酸化物球状微粒子
を低コストで連続生産できる製造方法を提供することを
目的とする。Therefore, according to the present invention, a wide variety of uniform metal oxide spherical fine particles can be continuously produced at a low cost by using a simple process in which the temperature distribution in the pipe length direction is defined. It is intended to provide a manufacturing method.
【0014】[0014]
【課題を解決するための手段】すなわち本発明は、金属
塩を含む水溶液を液滴径が0.1μmから100μmの微
小な液滴とし、該液滴をキャリアーガスを用いて気液混
相の状態で高温反応炉内へ送り、該反応炉入口部の温度
Tinが80〜300℃である反応炉内部で液滴に含まれ
る金属塩を熱分解して金属酸化物微粒子を生成させるこ
とを特徴とする金属酸化物微粒子の製造方法を提供する
ものである。Means for Solving the Problems In the present invention, an aqueous solution containing a metal salt is made into fine droplets having a droplet diameter of 0.1 μm to 100 μm, and the droplets are mixed in a gas-liquid phase using a carrier gas. characterized in feed to the high temperature reaction furnace, thereby generating a metal salt is thermally decomposed metal oxide fine particles contained in the reactor inside the droplet temperature T in is 80 to 300 ° C. of the reactor inlet The present invention provides a method for producing fine metal oxide particles.
【0015】以下、添付図面を参照して本発明を具体的
に説明する。図1は、本発明において用いる装置の一具
体例を示す概略図を示す。本発明の方法においては、液
槽1内にある金属塩水溶液を液送用循環ポンプ2を用い
て、微小な液滴を発生する液滴供給装置3へ連続供給
し、発生した液滴をキャリアーガス供給装置4より送ら
れてくるキャリアーガスに同伴させて温度分布制御が可
能な高温加熱体5を有する反応管6へ送り込み、反応管
6内で液滴の熱分解反応を行なわせて気固混相状態で金
属酸化物微粒子を生成させ、該微粒子をコロナ放電体8
を有する静電捕集器7内にある捕集板上へ静電沈着させ
る。なお、静電捕集器7を出る水蒸気を含むガスは、コ
ールドトラップ9およびフィルター10を通すことによ
り水分が除かれ、ポンプ11により強制的に排気され
る。なお、該微粒子の捕集は該捕集器7を用いる方法に
限定されず、フィルターを用いる方法等、その他の捕集
方法で行ってもよい。The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic view showing one specific example of the apparatus used in the present invention. In the method of the present invention, the aqueous solution of the metal salt in the liquid tank 1 is continuously supplied to the droplet supply device 3 for generating fine droplets by using the liquid circulation pump 2, and the generated droplets are used as a carrier. The carrier gas sent from the gas supply device 4 is sent along with the carrier gas to a reaction tube 6 having a high-temperature heating body 5 capable of controlling temperature distribution, and a thermal decomposition reaction of droplets is performed in the reaction tube 6 to solidify gas. The metal oxide fine particles are generated in the mixed phase, and the fine particles are used for the corona discharge body 8.
Is electrostatically deposited on the collecting plate in the electrostatic collector 7 having. The gas containing water vapor, which flows out of the electrostatic collector 7, has its water content removed by passing through the cold trap 9 and the filter 10, and is forcibly exhausted by the pump 11. The collection of the fine particles is not limited to the method using the collector 7, and may be performed by other collection methods such as a method using a filter.
【0016】金属塩として用いられる金属元素は、具体
的には、アルカリ金属、アルカリ土類金属、遷移金属で
ある。例えば、アルカリ金属としては、Li、Na、K、
Rb、Cs、Fr等、アルカリ土類金属としては、Be、M
g、Ca、Sr、Ba、Ra等、遷移金属としては、周期表
第4周期のSc、Ti、V、Cr、Mn、Fe、Co、Ni、
Cu、Zn、第5周期のY、Zr、Nb、Mo、Tc、Ru、
Rh、Pd、Ag、Cd、第6周期のLa、Hf、Ta、W、
Re、Os、Ir、Pt、Au、Hg等が挙げられる。The metal element used as the metal salt is specifically an alkali metal, an alkaline earth metal or a transition metal. For example, as the alkali metal, Li, Na, K,
Examples of alkaline earth metals such as Rb, Cs and Fr include Be and M
The transition metals such as g, Ca, Sr, Ba, Ra, etc. are Sc, Ti, V, Cr, Mn, Fe, Co, Ni of the 4th period of the periodic table,
Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru in the fifth cycle,
Rh, Pd, Ag, Cd, La, Hf, Ta, W of the sixth period,
Examples thereof include Re, Os, Ir, Pt, Au and Hg.
【0017】塩の種類としては、塩酸塩、硝酸塩、硫酸
塩、リン酸塩、炭酸塩、酢酸塩、2種類以上の塩で構成
されている複塩、錯イオンを含む錯塩等が挙げられ、こ
れらは無水塩、含水塩のどちらでもよい。具体的には、
金属塩としては、Ti(SO4)2、CuSO4・5H2O、Z
n(NO3)2・6H2O、Ca(NO3)2・4H2O、CaC
l2、MgCO3、Fe3(PO4)2、Cu(CH3COO)2等、
複塩としては、KMgCl3、AlK(SO4)2等、錯塩とし
ては、K3〔Fe(CN)6〕、〔CoCl(NH3)5〕Cl2等
が挙げられる。これらの金属塩は単独で、あるいは混合
物として用いられる。混合物としては、例えば、チタン
塩と亜鉛塩の混合物を用いた場合、熱分解温度により、
酸化亜鉛と酸化チタンの混合物または複合物であるチタ
ン酸亜鉛(Zn2TiO4)が得られる。Examples of the type of salt include a hydrochloride, a nitrate, a sulfate, a phosphate, a carbonate, an acetate, a double salt composed of two or more kinds of salts, a complex salt containing a complex ion, and the like. These may be either anhydrous salts or hydrous salts. In particular,
Metal salts include Ti (SO 4 ) 2 , CuSO 4 .5H 2 O, Z
n (NO 3) 2 · 6H 2 O, Ca (NO 3) 2 · 4H 2 O, CaC
l 2 , MgCO 3 , Fe 3 (PO 4 ) 2 , Cu (CH 3 COO) 2, etc.,
Examples of the double salt include KMGCl 3 , AlK (SO 4 ) 2 and the like, and examples of the complex salt include K 3 [Fe (CN) 6 ] and [CoCl (NH 3 ) 5 ] Cl 2 . These metal salts may be used alone or as a mixture. As the mixture, for example, when using a mixture of titanium salt and zinc salt, depending on the thermal decomposition temperature,
Zinc titanate (Zn 2 TiO 4 ) is obtained, which is a mixture or composite of zinc oxide and titanium oxide.
【0018】金属塩溶液の溶媒としては、水、有機溶媒
を単独で、あるいはそれらを組合せて用いることができ
るが、操作時の安全性の面からは、水を用いるのが好ま
しい。有機溶媒としては、例えば、メタノール、エタノ
ール等のアルコール、N,N−ジメチルホルムアミド、
ジメチルスルホキシド、ヘキサメチルホスホルアミド等
の極性溶媒等が挙げられる。また、金属塩溶液の濃度は
10-5モル/リットルから20モル/リットルの範囲で
あり、好ましくは、10-4モル/リットルから10モル
/リットルの範囲がよい。溶液濃度が10-5モル/リッ
トルより薄い場合、金属酸化物微粒子の生成量が極端に
少なくなり、また、溶液濃度が20モル/リットルより
濃い場合、溶液粘度が増加しすぎて微小液滴化が困難と
なる。As the solvent for the metal salt solution, water or an organic solvent may be used alone or in combination, but it is preferable to use water from the viewpoint of safety during operation. Examples of the organic solvent include alcohols such as methanol and ethanol, N, N-dimethylformamide,
Examples include polar solvents such as dimethyl sulfoxide and hexamethylphosphoramide. The concentration of the metal salt solution is in the range of 10 -5 mol / liter to 20 mol / liter, preferably 10 -4 mol / liter to 10 mol / liter. When the solution concentration is lower than 10 -5 mol / liter, the amount of metal oxide fine particles produced is extremely small, and when the solution concentration is higher than 20 mol / liter, the solution viscosity increases excessively to form fine droplets. Becomes difficult.
【0019】キャリアーガスとは、不活性ガスまたは熱
分解反応の進行を妨げないガスを言い、例えば、ヘリウ
ム、空気、窒素等が挙げられる。キャリアーガスの流量
は、反応管6内での金属塩を含む液滴の滞留時間が1秒
より短くならないようにその流量を調節する。The carrier gas refers to an inert gas or a gas that does not hinder the progress of the thermal decomposition reaction, and examples thereof include helium, air and nitrogen. The flow rate of the carrier gas is adjusted so that the residence time of the droplet containing the metal salt in the reaction tube 6 does not become shorter than 1 second.
【0020】溶液の微小液滴化方法としては、超音波振
動による方法や噴霧ノズルを用いる方法等があるが、液
滴径分布が狭くかつ微小な液滴を得るには、好ましくは
超音波振動による方法が良い。As a method for forming a solution into fine droplets, there are a method using ultrasonic vibration, a method using a spray nozzle, and the like. In order to obtain a fine droplet having a narrow droplet diameter distribution, ultrasonic vibration is preferable. Method is better.
【0021】液滴径は、0.1μmから100μmの範
囲で、液滴径分布はなるべく狭いものが好ましい。液滴
径が0.1μmより小さい場合、生成する金属酸化物微
粒子径は最大でも0.01μm程度で、その領域の微粒
子は超微粒子と呼ばれ、ブラウン拡散が大きいために反
応管内壁への沈着量が非常に多くなり、生成微粒子の歩
留まりが悪くなる。また、液滴径が100μmより大き
い場合、生成する金属酸化物微粒子径は小さくても数十
μm程度で、粒子の微粒化が困難となる。なお液滴径は
気液混相の状態で測定することが好ましく、例えば光散
乱式粒度分布計測機で測定できる。The droplet diameter is preferably in the range of 0.1 μm to 100 μm, and the droplet diameter distribution is preferably as narrow as possible. When the droplet diameter is smaller than 0.1 μm, the diameter of the produced metal oxide fine particles is about 0.01 μm at the maximum, and the fine particles in that area are called ultrafine particles. Because of the large Brownian diffusion, deposition on the inner wall of the reaction tube The amount becomes very large, and the yield of the produced fine particles deteriorates. When the droplet diameter is larger than 100 μm, even if the diameter of the produced metal oxide fine particles is small, it is about several tens of μm, and it becomes difficult to atomize the particles. The droplet diameter is preferably measured in a gas-liquid mixed phase state, and can be measured, for example, by a light scattering type particle size distribution measuring instrument.
【0022】本発明により得られる金属酸化物微粒子
は、単分散性が良く、噴霧溶液の濃度調整により、0.
01μmから数十μmの範囲のものが得られるが、生成
微粒子の歩留まりや微粒化による機能向上を考慮した場
合、好ましくは0.05μmから5μmの範囲が良い。
なお金属酸化物微粒子径は、種々の方法、例えば走査型
電子顕微鏡を用いて測定できる。The metal oxide fine particles obtained by the present invention have good monodispersibility, and the concentration of the spray solution can be adjusted to 0.
The range of 01 μm to several tens of μm can be obtained, but the range of 0.05 μm to 5 μm is preferable in view of the yield of the produced fine particles and the improvement in function due to atomization.
The diameter of the metal oxide fine particles can be measured by various methods, for example, using a scanning electron microscope.
【0023】反応炉は、反応管6において、半径方向に
対して、等温部がなるべく広く保たれるように加熱体5
を温度制御する。なお、本発明における反応炉入口温度
および反応炉内温度とは雰囲気ガス温度をいう。反応炉
内の温度は、溶媒として水を用いる場合、好ましくは8
0℃から2000℃の範囲が良い。温度が80℃より低
いと液滴の水分が蒸発しにくく、また、2000℃より
高いと水蒸気爆発の可能性がある。また、溶媒として有
機溶媒を用いる場合、好ましくは50℃から400℃の
範囲がよい。温度が50℃より低いと液滴の有機溶媒分
が蒸発しにくく、また、400℃より高いとススが発生
する。In the reaction furnace, in the reaction tube 6, the heating element 5 is arranged so that the isothermal portion is kept as wide as possible in the radial direction.
Control the temperature. In addition, the reactor inlet temperature and the reactor temperature in the present invention refer to ambient gas temperature. The temperature in the reaction furnace is preferably 8 when water is used as the solvent.
The range of 0 ° C to 2000 ° C is preferable. If the temperature is lower than 80 ° C, the water content of the droplets is hard to evaporate, and if it is higher than 2000 ° C, there is a possibility of steam explosion. When an organic solvent is used as the solvent, it is preferably in the range of 50 ° C to 400 ° C. If the temperature is lower than 50 ° C, the organic solvent component of the liquid droplets is hard to evaporate, and if it is higher than 400 ° C, soot is generated.
【0024】溶媒が水の場合、反応炉入口温度が80℃
以上、300℃以下となるように加熱体5を温度制御す
る。反応炉入口温度が80℃未満では液滴中の水分が蒸
発しにくく、また、300℃を越えると溶媒の蒸発およ
び熱分解反応物質である溶質の熱分解が同時に、かつ急
激に起こるため、生成微粒子は球状ではなく破砕状とな
る。反応炉出口において反応率が90%となる反応炉長
さをL0とし、反応炉入口からの距離L(L=0.1×
L0)における温度をTLとした時、反応炉入口からLま
での領域で温度勾配α〔α=(TL−Tin)/L〕、0
≦α≦50℃/cmの時、破砕粒子が生成せずに均一な
球状微粒子が生成するため、前記のTinおよびαの条件
を満足するように、加熱体5を温度制御する。更に好ま
しくは、温度勾配は0≦α≦40℃/cmである。溶媒
が水の場合、温度勾配が0℃/cmより小さいと溶媒の
蒸発が起こりにくく、かつ溶質の熱分解反応も起こりに
くくなる。また、50℃/cmより大きいと、溶媒の蒸
発および熱分解反応物質である溶質の熱分解が同時に、
かつ急激に起こるため、生成微粒子は球状でなく破砕状
となる。When the solvent is water, the reactor inlet temperature is 80 ° C.
As described above, the temperature of the heating element 5 is controlled so as to be 300 ° C. or lower. When the reactor inlet temperature is lower than 80 ° C, the water content in the droplets is hard to evaporate, and when it exceeds 300 ° C, the evaporation of the solvent and the thermal decomposition of the solute which is the thermal decomposition reaction substance occur simultaneously and rapidly. The fine particles are not spherical but crushed. The reactor length at which the reaction rate at the reactor outlet is 90% is L 0, and the distance from the reactor inlet is L (L = 0.1 ×
When the temperature at L 0 ) is TL , the temperature gradient α [α = ( TL −T in ) / L], 0 in the region from the reactor inlet to L
When ≦ α ≦ 50 ° C./cm, crushed particles are not generated and uniform spherical fine particles are generated. Therefore, the temperature of the heating element 5 is controlled so as to satisfy the above conditions of T in and α. More preferably, the temperature gradient is 0 ≦ α ≦ 40 ° C./cm. When the solvent is water and the temperature gradient is less than 0 ° C./cm, the solvent is less likely to evaporate, and the solute thermal decomposition reaction is less likely to occur. If it is higher than 50 ° C./cm, the evaporation of the solvent and the thermal decomposition of the solute, which is a thermal decomposition reaction substance, are
Moreover, since it occurs rapidly, the produced fine particles are not spherical but crushed.
【0025】溶媒が有機溶媒の場合、反応炉入口温度が
50℃以上、100℃以下になるように加熱体5を温度
制御する。反応炉入口温度が50℃未満では液滴中の有
機溶媒が蒸発しにくく、また、100℃を越えると溶媒
の蒸発および熱分解反応物質である溶質の熱分解が同時
に、かつ急激に起こるため、生成微粒子は球状ではなく
破砕状となる。また、反応管入口からLまでの領域にお
いて、0≦α≦25℃/cmの時、破砕状粒子が生成せ
ずに均一な球状微粒子が生成するため、前記のTinおよ
びαの条件を満足するように、加熱体5を温度制御す
る。溶媒が有機溶媒の場合、温度勾配が0℃/cmより
小さいと溶媒の蒸発が起こりにくく、かつ溶質の熱分解
反応も起こりにくくなる。また、25℃/cmより大き
いと、溶媒の蒸発および熱分解反応物質である溶質の熱
分解が同時に、かつ急激に起こるため、生成微粒子は球
状でなく破砕状となる。When the solvent is an organic solvent, the temperature of the heating element 5 is controlled so that the reaction furnace inlet temperature is 50 ° C. or higher and 100 ° C. or lower. When the reactor inlet temperature is lower than 50 ° C., the organic solvent in the droplets is difficult to evaporate, and when it exceeds 100 ° C., the evaporation of the solvent and the thermal decomposition of the solute which is the thermal decomposition reaction substance occur simultaneously and rapidly. The produced fine particles are not spherical but crushed. Further, in the region from the reaction tube inlet to L, when 0 ≦ α ≦ 25 ° C./cm, uniform spherical fine particles are formed without forming crushed particles, so that the above conditions of T in and α are satisfied. The temperature of the heating element 5 is controlled so as to do so. When the solvent is an organic solvent, if the temperature gradient is less than 0 ° C./cm, evaporation of the solvent is less likely to occur, and thermal decomposition reaction of the solute is less likely to occur. On the other hand, if it is higher than 25 ° C./cm, evaporation of the solvent and thermal decomposition of the solute as a thermal decomposition reaction substance occur rapidly at the same time, so that the produced fine particles are not spherical but crushed.
【0026】反応炉入口よりLの位置から出口までの管
長方向に対する温度分布においては、溶媒が水の場合に
は、前記の80℃から2000℃の範囲内にある任意の
温度分布でよく、溶媒が有機溶媒の場合には、前記の5
0℃から400℃の範囲内にある温度分布であれば任意
の温度分布でよいが、生成微粒子の結晶性向上のために
はTLよりも高温にすることが望ましい。In the temperature distribution in the pipe length direction from the position L to the outlet of the reaction furnace, when the solvent is water, any temperature distribution within the range of 80 ° C. to 2000 ° C. may be used. When is an organic solvent, the above 5
Any temperature distribution may be used as long as it has a temperature distribution within the range of 0 ° C. to 400 ° C., but is preferably higher than T L in order to improve the crystallinity of the produced fine particles.
【0027】本発明においては、金属塩の熱分解反応を
促進させるため、反応炉内で200℃以上、好ましくは
300℃以上の温度領域を設けることが望ましい。熱分
解反応としては、例えば、 1)Ti(SO4)2 → TiO2+SOx 2)CuSO4 → CuO+SOx 3)Zn(NO3)2 → ZnO+NOx 4)Ca(NO3)2 → CaO+NOx 5)MgCO3 → MgO+CO2 等が挙げられる。In the present invention, in order to accelerate the thermal decomposition reaction of the metal salt, it is desirable to provide a temperature range of 200 ° C. or higher, preferably 300 ° C. or higher in the reaction furnace. As the thermal decomposition reaction, for example, 1) Ti (SO 4 ) 2 → TiO 2 + SO x 2) CuSO 4 → CuO + SO x 3) Zn (NO 3 ) 2 → ZnO + NO x 4) Ca (NO 3 ) 2 → CaO + NO x 5) MgCO 3 → MgO + CO 2 and the like.
【0028】[0028]
【実施例】つぎに、実施例を挙げて本発明をさらに詳し
く説明するが、これらに限定するものではない。 実施例1 Zn(NO3)2・6H2O(硝酸亜鉛六水和物)と純水を用い
て、硝酸亜鉛水溶液を0.1モル/リットルに調整した
ものを作成し、キャリアーガスとして窒素ガスを使用
し、図1に示す装置を用いて酸化亜鉛微粒子を作成し
た。平均液滴径は5μmであった。この平均液滴径は光
散乱式粒度分布計測機(パーティクルサイザー、(株)日
本レーザー製)を用いて測定した。以下、比較例1、実
施例2でも同様の方法で測定した。さらに詳しく説明す
ると、反応管には磁性チューブ(内径35mm、長さ6
0cm)を用い、キャリアーガス流量はl.0リットル/
分で一定とした。反応炉の温度分布は図2に示すように
凸型であり、反応炉入口温度が200℃、反応炉入口か
ら管長方向に6cmの位置での温度が360℃、温度勾
配αが26.7℃/cmとした。ただし、反応炉の温度
分布測定については、熱電対を反応管軸に沿って管長さ
方向に移動させながら温度測定器を用いて測定した。以
下、比較例1、実施例2でも同様の方法で反応炉の温度
分布を測定した。EXAMPLES Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting. Example 1 Zn (NO 3 ) 2 .6H 2 O (zinc nitrate hexahydrate) and pure water were used to prepare a zinc nitrate aqueous solution adjusted to 0.1 mol / liter, and nitrogen was used as a carrier gas. Fine particles of zinc oxide were prepared by using a gas and an apparatus shown in FIG. The average droplet diameter was 5 μm. The average droplet diameter was measured using a light scattering type particle size distribution measuring device (Particlesizer, manufactured by Nippon Laser Co., Ltd.). Hereinafter, the same method was used in Comparative Example 1 and Example 2. More specifically, the reaction tube has a magnetic tube (inner diameter 35 mm, length 6).
0 cm) and the carrier gas flow rate is 1.0 liter /
It was constant in minutes. The temperature distribution of the reaction furnace is convex as shown in FIG. 2, the reaction furnace inlet temperature is 200 ° C., the temperature at the position 6 cm from the reaction furnace inlet in the pipe length direction is 360 ° C., and the temperature gradient α is 26.7 ° C. / Cm. However, the temperature distribution of the reaction furnace was measured using a temperature measuring device while moving the thermocouple in the tube length direction along the axis of the reaction tube. Hereinafter, also in Comparative Example 1 and Example 2, the temperature distribution in the reaction furnace was measured by the same method.
【0029】前記条件で生成した酸化亜鉛微粒子の結晶
形は六方晶系ウルツ鉱型であった。酸化亜鉛粒子径は平
均径(個数基準)で約0.97μmであり、粒径分布(個数
基準)は、0.5μm以下が10%、0.5〜1.0μmが
50%、1.0〜1.5μmが30%、1.5μm以上が
10%であった。なお、生成した酸化亜鉛微粒子の結晶
形はX線回折装置で測定し、また、微粒子径は走査型電
子顕微鏡で測定した。以下、比較例1、実施例2でも同
様の方法で測定した。The zinc oxide fine particles produced under the above conditions had a hexagonal wurtzite type crystal form. The zinc oxide particle size is about 0.97 μm on average (number basis), and the particle size distribution (number basis) is 0.5% or less 10%, 0.5-1.0 μm 50%, 1.0 .About.1.5 .mu.m was 30%, and 1.5 .mu.m or more was 10%. The crystal form of the produced zinc oxide fine particles was measured by an X-ray diffractometer, and the fine particle diameter was measured by a scanning electron microscope. Hereinafter, the same method was used in Comparative Example 1 and Example 2.
【0030】つぎに、生成した酸化亜鉛微粒子の走査型
電子顕微鏡写真を図3の図面代用写真に示す。図3より
明らかなように、生成微粒子は略球状を呈していた。Next, a scanning electron micrograph of the produced zinc oxide fine particles is shown in the drawing-substitute photograph of FIG. As is clear from FIG. 3, the produced fine particles had a substantially spherical shape.
【0031】比較例1 Zn(NO3)2・6H2Oと純水を用いて硝酸亜鉛水溶液を
0.1モル/リットルに調整したものを使用し、キャリ
ヤーガスには窒素ガスを使用し、図1に示す装置を用い
て酸化亜鉛微粒子を作成した。金属塩溶液の平均液滴径
は5μmであった。キャリヤーガス流量は1.0リット
ル/分で一定とし、反応管は実施例1と同じものを用い
た。反応炉の温度分布は、図2に示すように、反応炉入
口温度が400℃、反応炉入口から管長方向に6cmの
位置での温度が620℃、温度勾配αが36.7℃/c
m、反応炉入口から管長方向に14cmの位置以後では
700℃一定とした。[0031] Using Comparative Example 1 Zn (NO 3) 2 · 6H 2 O and pure water was used after adjusting the aqueous solution of zinc nitrate of 0.1 mol / liter, using nitrogen gas in the carrier gas, Zinc oxide fine particles were prepared using the apparatus shown in FIG. The average droplet diameter of the metal salt solution was 5 μm. The carrier gas flow rate was constant at 1.0 liter / min, and the same reaction tube as in Example 1 was used. As shown in FIG. 2, the temperature distribution of the reactor is 400 ° C. at the inlet of the reactor, 620 ° C. at a position of 6 cm in the pipe length direction from the inlet of the reactor, and temperature gradient α is 36.7 ° C./c.
m, and after the position of 14 cm in the pipe length direction from the reactor inlet, the temperature was kept constant at 700 ° C.
【0032】前記条件で生成した酸化亜鉛微粒子の結晶
形は六方晶系ウルツ鉱型であった。粒子径は平均径(個
数基準)で約0.90μmであり、粒径分布(個数基準)
は、0.5μm以下が10%、0.5〜1.0μmが5
0%、1.0〜1.5μmが30%、1.5μm以上が1
0%であった。The zinc oxide fine particles produced under the above conditions had a hexagonal wurtzite crystal form. The average particle size (number basis) is about 0.90 μm, and the particle size distribution (number basis)
Is less than 0.5 μm is 10%, 0.5 to 1.0 μm is 5
0%, 1.0-1.5 μm is 30%, 1.5 μm or more is 1
It was 0%.
【0033】つぎに、生成した酸化亜鉛微粒子の走査型
電子顕微鏡写真を図4の図面代用写真に示す。図4から
明らかなように、破砕状微粒子が生成していた。これ
は、実施例1と比較して反応炉入口温度が400℃と高
温であるためである。Next, a scanning electron micrograph of the produced zinc oxide fine particles is shown in the drawing-substitute photograph of FIG. As is clear from FIG. 4, crushed fine particles were generated. This is because the reactor inlet temperature is as high as 400 ° C. as compared with Example 1.
【0034】実施例2 Zn(NO3)2・6H2OとTiCl4の(モル比で1:1)混
合物と純水を用いて溶液濃度を0.1モル/リットルに
調整したものを使用し、キャリヤーガスには空気を使用
し、図1に示す装置を用いて酸化亜鉛と二酸化チタンの
混合物を作成した。金属塩溶液の平均液滴径は4μmで
あった。キャリヤーガス流量は1.0リットル/分で一
定とし、反応管は実施例1と同じものを用いた。反応炉
の温度分布は、図2に示すように、反応炉入口温度が1
00℃、反応炉入口から管長方向に6cmの位置での温
度は230℃、温度勾配αが21.7℃/cm、反応炉
入口から管長方向に30cmの位置以後では650℃一
定とした。Example 2 A mixture of Zn (NO 3 ) 2 .6H 2 O and TiCl 4 (molar ratio 1: 1) and pure water were used to adjust the solution concentration to 0.1 mol / liter. Then, air was used as the carrier gas, and a mixture of zinc oxide and titanium dioxide was prepared using the apparatus shown in FIG. The average droplet diameter of the metal salt solution was 4 μm. The carrier gas flow rate was constant at 1.0 liter / min, and the same reaction tube as in Example 1 was used. As shown in FIG. 2, the temperature distribution in the reaction furnace has a reactor entrance temperature of 1
The temperature was 00 ° C., the temperature at a position 6 cm from the reactor inlet in the pipe length direction was 230 ° C., the temperature gradient α was 21.7 ° C./cm, and 650 ° C. was constant after the position 30 cm from the reactor inlet in the pipe length direction.
【0035】前記条件で生成した酸化亜鉛と二酸化チタ
ンの混合微粒子の結晶形は六方晶系ウルツ鉱型とアナタ
ーゼ型が混在していた。粒子径は平均径(個数基準)で約
0.67μmであり、粒径分布(個数基準)は、0.5μm
以下が30%、0.5〜1.0μmが50%、1.0〜1.
5μmが10%、1.5μm以上が10%であった。The crystal forms of the mixed fine particles of zinc oxide and titanium dioxide produced under the above conditions were a mixture of hexagonal wurtzite type and anatase type. The average particle size (number basis) is about 0.67μm, and the particle size distribution (number basis) is 0.5μm.
The following is 30%, 0.5-1.0 μm is 50%, 1.0-1.
5 μm was 10%, and 1.5 μm or more was 10%.
【0036】つぎに、生成した混合微粒子の走査型電子
顕微鏡写真を図5の図面代用写真に示す。図5から明ら
かなように、生成した混合微粒子は略球状を呈してお
り、比較例1のような破砕状微粒子は存在しなかった。Next, a scanning electron micrograph of the produced mixed fine particles is shown in the drawing-substitute photograph of FIG. As is clear from FIG. 5, the produced mixed fine particles had a substantially spherical shape, and the crushed fine particles as in Comparative Example 1 were not present.
【0037】[0037]
【発明の効果】以上述べたように、本発明によれば、広
範な種類の金属塩を出発原料として、それらの水溶液か
ら微小液滴を作り、該液滴を温度分布の制御された高温
反応炉内で熱分解反応させるという簡便な製造プロセス
により、広範な種類の均一な金属酸化物球状微粒子を低
コストで連続生産できる。また、得られた金属酸化物微
粒子は半導性を有するため、紫外線遮蔽能力に加えて、
光導電性、蛍光性、圧電性等の金属酸化物特有の機能を
有する。As described above, according to the present invention, a wide variety of metal salts are used as a starting material to form fine droplets from an aqueous solution thereof, and the droplets are subjected to a high temperature reaction in which the temperature distribution is controlled. By a simple manufacturing process in which a thermal decomposition reaction is performed in a furnace, a wide variety of uniform metal oxide spherical fine particles can be continuously produced at low cost. Further, since the obtained metal oxide fine particles have semiconductivity, in addition to the ultraviolet shielding ability,
It has functions peculiar to metal oxides such as photoconductivity, fluorescence, and piezoelectricity.
【図1】 本発明において用いる装置の一具体例を示す
概略図である。FIG. 1 is a schematic diagram showing a specific example of an apparatus used in the present invention.
【図2】 実施例1、比較例1および実施例2の反応炉
温度分布を示すグラフである。FIG. 2 is a graph showing temperature distributions of a reactor in Example 1, Comparative Example 1 and Example 2.
【図3】 実施例1の酸化亜鉛微粒子の粒子形状を示す
図面代用写真である。3 is a drawing-substituting photograph showing the particle shape of the zinc oxide particles of Example 1. FIG.
【図4】 比較例1の酸化亜鉛微粒子の粒子形状を示す
図面代用写真である。4 is a drawing-substituting photograph showing the particle shape of zinc oxide particles of Comparative Example 1. FIG.
【図5】 実施例2の酸化亜鉛−二酸化チタン混合微粒
子の粒子形状を示す図面代用写真である。FIG. 5 is a drawing-substituting photograph showing the particle shape of zinc oxide-titanium dioxide mixed particles of Example 2.
1:液槽、2:液送用循環ポンプ、3:液滴供給装置、
4:キャリアーガス供給装置、5:高温加熱体、6:反
応管、7:静電捕集器、8:コロナ放電体、9:コール
ドトラップ、10:フィルター、11:ポンプ1: Liquid tank, 2: Circulation pump for sending liquid, 3: Droplet supply device,
4: Carrier gas supply device, 5: High temperature heating body, 6: Reaction tube, 7: Electrostatic collector, 8: Corona discharge body, 9: Cold trap, 10: Filter, 11: Pump
Claims (3)
から100μmの微小な液滴とし、該液滴をキャリアー
ガスを用いて気液混相の状態で高温反応炉内へ送り、該
反応炉入口部の温度Tinが80〜300℃である反応炉
内部で液滴に含まれる金属塩を熱分解して金属酸化物微
粒子を生成させることを特徴とする金属酸化物微粒子の
製造方法。1. A droplet size of an aqueous solution containing a metal salt is 0.1 μm.
To 100 μm as fine droplets, and the droplets are sent to a high temperature reactor in a gas-liquid mixed state using a carrier gas, and the temperature T in at the reactor inlet is 80 to 300 ° C. inside the reactor. A method for producing fine metal oxide particles, which comprises thermally decomposing the metal salt contained in the droplets to produce fine metal oxide particles.
る反応炉長さをL0とし、反応炉入口からの距離L(L=
0.1×L0)における温度をTLとした時、反応炉入口
からLまでの領域で、温度勾配α〔α=(TL−Tin)
/L〕が0〜50℃/cmである温度分布条件にて金属
酸化物微粒子を生成させる請求項1記載の製造方法。2. The length L 0 of the reactor at which the reaction rate is 90% at the reactor outlet, and the distance L (L = L
Assuming that the temperature at 0.1 × L 0 ) is T L , the temperature gradient α [α = (T L −T in )
/ L] is a temperature distribution condition of 0 to 50 ° C./cm, and the production method according to claim 1, wherein the metal oxide fine particles are generated.
合物の塩であり、得られた金属酸化物が酸化亜鉛、二酸
化チタンまたはそれらの混合物あるいは複合物である請
求項1または2記載の製造方法。3. The production method according to claim 1, wherein the metal salt is a salt of zinc, titanium or a mixture thereof, and the obtained metal oxide is zinc oxide, titanium dioxide or a mixture or complex thereof. ..
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11881092A JPH05310425A (en) | 1992-05-12 | 1992-05-12 | Production of metal oxide fine particle |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11881092A JPH05310425A (en) | 1992-05-12 | 1992-05-12 | Production of metal oxide fine particle |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH05310425A true JPH05310425A (en) | 1993-11-22 |
Family
ID=14745696
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11881092A Pending JPH05310425A (en) | 1992-05-12 | 1992-05-12 | Production of metal oxide fine particle |
Country Status (1)
Country | Link |
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JP (1) | JPH05310425A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2845247A1 (en) * | 1978-10-18 | 1980-04-30 | Schneider Co Optische Werke | LENS |
WO1997024288A1 (en) * | 1995-12-27 | 1997-07-10 | Tohkem Products Corporation | Stable anatase titanium dioxide and process for preparing the same |
KR100441851B1 (en) * | 2001-06-04 | 2004-07-27 | 안강호 | Apparatus for manufacturing particles using corona discharge and method thereof |
US6827758B2 (en) | 2001-05-30 | 2004-12-07 | Tdk Corporation | Method for manufacturing magnetic metal powder, and magnetic metal powder |
US7094289B2 (en) | 2002-08-07 | 2006-08-22 | Shoei Chemical Inc. | Method for manufacturing highly-crystallized oxide powder |
FR2948034A1 (en) * | 2009-07-20 | 2011-01-21 | Centre Nat Rech Scient | PARTICLE SYNTHESIS THERMOHYDROLYSIS OF MINERAL PRECURSORS |
-
1992
- 1992-05-12 JP JP11881092A patent/JPH05310425A/en active Pending
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2845247A1 (en) * | 1978-10-18 | 1980-04-30 | Schneider Co Optische Werke | LENS |
WO1997024288A1 (en) * | 1995-12-27 | 1997-07-10 | Tohkem Products Corporation | Stable anatase titanium dioxide and process for preparing the same |
US6827758B2 (en) | 2001-05-30 | 2004-12-07 | Tdk Corporation | Method for manufacturing magnetic metal powder, and magnetic metal powder |
US7416795B2 (en) | 2001-05-30 | 2008-08-26 | Tdk Corporation | Method for manufacturing magnetic metal powder, and magnetic metal powder |
KR100441851B1 (en) * | 2001-06-04 | 2004-07-27 | 안강호 | Apparatus for manufacturing particles using corona discharge and method thereof |
US7094289B2 (en) | 2002-08-07 | 2006-08-22 | Shoei Chemical Inc. | Method for manufacturing highly-crystallized oxide powder |
FR2948034A1 (en) * | 2009-07-20 | 2011-01-21 | Centre Nat Rech Scient | PARTICLE SYNTHESIS THERMOHYDROLYSIS OF MINERAL PRECURSORS |
WO2011010056A1 (en) * | 2009-07-20 | 2011-01-27 | Centre National De La Recherche Scientifique (C.N.R.S) | Particle synthesis by means of the thermal hydrolysis of mineral precursors |
US8986648B2 (en) | 2009-07-20 | 2015-03-24 | Centre National De La Recherche Scientifique (C.N.R.S.) | Particle synthesis by means of the thermohydrolysis of mineral precursors |
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