JP2004223355A - Fine inorganic particle-dispersed fluid and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: ultra-fine solid particles produced by a solution method can flocculate easily to form large secondary particles by the recombination of the particles, a large amount of energy is required to break the flocculated particles, and the purity of the particles is apt to be lowered by the intrusion of foreign substances during breaking. <P>SOLUTION: To prevent the flocculation and agglomeration of the fine particles in a fine inorganic solid particle production process and contamination by the intrusion of the foreign substances in secondary cracking treatment in use or during cracking, a mixture comprising a water-soluble raw material compound for producing the fine particles, water, a water-insoluble medium oil, and preferably a water-insoluble surfactant is added with a base and irradiated with microwaves. In this way, a fluid in which nanometer-size particles are mono-dispersed is obtained. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、実質的に溶液状を呈する無機微粒子が均一に分散した流体の簡便な製造方法に関する。
【０００２】
【従来の技術】
金属あるいは金属酸化物等の無機固体微粉は、従来より触媒、磁性体や半導体等の工業用材料として各方面で重用されている。しかしながら、これまでミクロンオーダーで用いられていたこれら無機材料の粒径をナノオーダーにまで微細化すると、従来より触媒機能や記憶容量や寿命が数段優れたあるいは従来とは全く異なる新たな性能を発揮することが明らかになり、これらの超微粉化あるいは粒径分布幅の小さい微粒子の製造が強く求められている。
【０００３】
このような固体微粒子の合成方法として、固相焼結法や液相反応法等がある。固相反応法は一般に１０００℃前後の高温を必要とする。また、液相反応法では２００℃前後の温度で加圧下（１０〜１５気圧）で反応が進行する。液相法では結晶化速度が小さいため、通常は数時間から数日の反応時間を要する。この液相反応をマイクロ波照射下で実施すると、反応時間が数分から１時間程度にまで大幅に短縮でき、しかも粒径のそろった微細粒子が生成する。
【０００４】
【発明が解決しようとする課題】
溶液法で生成した超微細な固体粒子は、非常に凝集しやすく、粒子同士が再結合して粗大な二次粒子を形成しやすい。凝集した粒子を解砕するために多大のエネルギーを要すこと、更には解砕時に異物が混入して純度が低下しやすい等の欠点を有している。
【０００５】
液相法で微粒子を製造する場合、まず、原料である鉄やニッケル塩化物を溶媒の水に溶かし、これに塩基を添加してｐＨを調整した後、オートクレーブ中において２００℃程度まで加熱してフェライトを結晶化させる。生成したフェライトは水相の下部に沈積する。この反応物を濾過、洗浄、乾燥等を経て製品として回収する。生成した粒子を透過型電子顕微鏡（ＴＥＭ）で観察すると、直径１０ナノメートル程度の一次粒子が球状あるいは数珠状等に多数凝集、結合してミクロンオーダーの二次粒子を形成していることが確認された。
【０００６】
ナノオーダーの微粒子が凝集した粒子を解砕することは非常に難しく、また、多大なエネルギーを要する。更に、ナノオーダーの微粒子を積層させて使用する場合、ナノオーダーの微粒子が単分散した流体が必要である。
【０００７】
【課題を解決するための手段】
本発明者らは、無機固体微粒子製造過程における微粒の凝集、塊状化および利用に際しての二次的解砕処理あるいは解砕時の異物混入汚染等の問題点を解消するため、種々検討を行った結果、微粒子製造用水溶性原料化合物、水、水不溶性の媒体油および好ましくは水不溶性の界面活性剤よりなる混合物に塩基を加えてマイクロ波を照射することによりナノサイズ粒子の単分散した流体が得られることを見出した。
【０００８】
【発明の実施の形態】
本発明で用いる水溶性原料化合物は、塩化物、硝酸塩、硫酸塩、炭酸塩、酢酸塩などの水溶性塩が好適であるが、オキシ水酸化物、アルコキシドなども利用できる。なお、これらの化合物に限定されるものではなく、水に溶解する化合物を用いることができる。
【０００９】
例えば、Ｎｉフェライト合成を例にとれば、ＦｅＣｌ_３とＮｉＣｌ_２をそれぞれ所定量、水と混合して溶解し、これに水不溶性の媒体油と界面活性剤とを混合する。この水不溶性の媒体油は、反応によって生成するフェライト微粒子を速やかに分散させて凝集や粒成長を抑止すると共に、生成微粒子を安定に保持させるものである。この媒体油としては、原料水層との分別が容易な疎水性油が好ましく、更に、水よりも比重の小さい油の方が回収操作が一層容易であることから、常温液状のパラフィン類あるいはＢＴＸ等は、特に好ましい媒体油である。
【００１０】
界面活性剤は、生成フェライト微粒子が媒体油中に安定的に分散・保持するのに寄与しているものと考えられ、この機能を有するものであれば特に限定されることはない。例えば、各種の工業分野で使用されている界面活性剤が本発明法に使用できるが、水不溶性の非イオン系界面活性剤は特に好適な一例である。なお、このような媒体油と分散剤と原料水溶液との混合比は特に限定されるものではない。例えば媒体油の添加量は、容積比で原料水の１／１０から５倍程度が好適な範囲であり、界面活性剤の使用量は、媒体油の１／５容量倍程度以下にすることが特に好ましい。
【００１１】
金属塩水溶液と媒体油及び界面活性剤を混合して調製した原料溶液に、必要量の塩基を添加してｐＨを調製する。塩基としては、一般的な水酸化アルカリやアンモニア水等が用いられるが、高温下で熱分解してアンモニアを発生する尿素、ジアミン等を用いることもできる。
【００１２】
塩基を加えた原料溶液を耐圧性の優れ、マイクロ波透過性の良い回分式あるいは連続式の反応器内でマイクロ波を照射・加熱する。Ｎｉフェライトの場合、温度１００〜２００℃の所定温度まで急速に加熱し、その後必要に応じて所定時間、所定温度に保持する。マイクロ波の周波数は通常は２．４５ＧＨｚであるが、本質的にこれに限定されるものではない。
【００１３】
通常の伝導伝熱加熱方式の水熱反応では反応容器の外部から伝導あるいは対流により容器内部に温度が伝えられるため、外壁近傍の温度が高く、内部の温度が低く、結晶成長には非常に長時間を要する。マイクロ波法では極性基の回転による摩擦熱で内部から加熱され、局所的に高温となり迅速に反応が進行するものと考えられる。例えば、フェライトの場合、１８０℃、数時間から１０時間要する反応が、マイクロ波法では１５０℃では数分から１時間で結晶化が終了する。
【００１４】
本発明では、マイクロ波加熱によって生成した固体のフェライト微粒子は、原料水溶液相から媒体油相に移動して安定的に分散している。すなわち、原料調製時、下層にフェライト前駆体を含む水溶液相が、上層には界面活性剤を溶解した水不溶性の媒体油相が存在している。これにマイクロ波を照射すると、短時間に反応が進行し、フェライト微粒子が生成し、下層の水相から浮上して上層の媒体油中に移動して均一流体を示す。
【００１５】
比較例として、媒体油を添加せずに反応を行うと、フェライト微粒子は生成するが、生成した微粒子は水相の下部に沈積し、均一流体は生成しない。フェライトの真比重は５以上であるが、フェライトを均一に分散した流体は比重１の水に浮く。媒体油中に生成した親水性のミセルに取り込まれて安定化し、ミセル中ではナノサイズを保持しているものと推察される。
【００１６】
反応生成物は、媒体油相に均一分散しているため、原料水溶液相とは容易に分離回収でき、且つ、脱イオン水で繰り返し洗浄することができる。
【００１７】
従来、磁性物質を或る媒体液中に均一に分散させた磁性流体の製造に関して、多くの特許（例えば特開２００１−１６７９１９、特開平１０−２４１９２８、特開平６−６９０２１等）が開示されているが、いずれもナノ粒子を調製した後、流体として分散させる方法で、非常に多くの工程を経て製造される。本発明法では磁性材料微粒子の生成と磁性流体の製造とが同時に進行するもので、工程を簡略化できるのみならず、微粒子生成工程に媒体油が存在することで粒子の二次成長が抑止でき、粒径の揃った、異物混入のないナノ粒子分散流体を簡単に製造できる。
以下、本発明の効果を、実施例によって更に詳しく説明する。
【００１８】
【実施例１】
１．３５ｇのＦｅＣｌ_３・６Ｈ_２Ｏと０．５４ｇのＮｉＣｌ_２・６Ｈ_２Ｏとを２０ｍｌの水に溶解し、これに２０ｍｌのデカンと１ｍｌのソルビタン骨格を有する水不溶性の界面活性剤および２５％濃度のアンモニア水３ｍｌとを攪拌しながら添加して原料溶液を調製し、その原料溶液をＴＦＭ（トリフルオロメタキシル）製の耐圧反応器に充填し、２．４５ＧＨｚの周波数のマイクロ波加熱によって１５０℃まで加熱し、その温度で３０ｍｉｎ保持した後、加熱を終了し、直ちに常温まで冷却した。冷却後の反応物をビーカーに移し、静置した。内容物は下層の透明な水相と上層の黒褐色流体が得られた。水相を分離し、脱イオン水で洗浄して均一な褐色の流体を得た。この均一な褐色流体は磁石に吸い寄せられ、磁性を有することを確認した。この流体は数ヶ月後も分離することなく安定した流体であった。写真１に示すように流体は磁石に吸い寄せられている。
【００１９】
【比較例１】
実施例１と同一条件で、デカンのみを使用せず、さらに水２０ｍｌを加えた条件で反応を行った。反応後の生成物をビーカーに移したところ、透明な水相の下部に褐色のフェライト微粒子が沈積した。
【００２０】
【比較例２】
実施例１と同一条件で、界面活性剤を添加しない場合、あるいはデカンと界面活性剤両方を添加しない場合についても実験した結果、全て褐色のフェライト粒子が底部に沈積するのみで、均一に分散した流体は得られなかった。更に、親水性の界面活性剤についても同一条件で実験したが、流体フェライトは生成しなかった。
【００２１】
【実施例２】
媒体油としてトルエンを用いた以外は実施例１と同様の条件でフェライトの製造実験を行った結果、実施例１と同様に、水相の上に浮遊する均一な流体フェライト相が作成された。
【００２２】
【実施例３】
実施例１で得た褐色流体と、比較例２の界面活性剤のみ不使用で得た褐色の沈殿について、生成物全量を孔径０．４５ミクロンの定量濾紙で濾過した。その結果、褐色の沈殿物は濾別されたが、均一流体は濾紙を通過し、濾別できなかった。濾別された褐色沈殿物はＸ線回折の結果、スピネル型フェライトであることを確認した。流体フェライトについて希釈して散乱法で粒径を測定した結果、十数ナノメーター以下であることを確認した。
【００２３】
【実施例４】
１．６１１ｇのＺｒＣｌ_２・８Ｈ_２Ｏを２０ｍｌの水に溶解し、これに２０ｍｌのデカンと２ｍｌのソルビタン骨格を有する非イオン性界面活性剤および２５％濃度のアンモニア水３ｍｌとを攪拌しながら添加して原料溶液を調製した。この原料溶液をＴＦＭ製の耐圧反応器に充填し、２．４５ＧＨｚの周波数のマイクロ波加熱によって１５０℃まで加熱し、その温度で３０ｍｉｎ保持した後、加熱を終了し、常温まで冷却した。冷却後の反応物を全量ガラスビーカーに移し、静置した。内容物は下層の透明な水相と上層のベージュ色の流体ジルコニア相とに分離した。上層の流体ジルコニア均一相は安定で、２４時間経過後も分離しなかった。
【００２４】
【比較例３】
比較例として、実施例４と同一条件で、界面活性剤を使用しない場合、あるいは界面活性剤とデカンの両方を使用しない場合について試験を行った。いずれも、透明な水相の底部に白色のジルコニア微粒子が沈積し、均一に分散した流体は得られなかった。
【００２５】
【発明の効果】
従来法ではナノ粒子をまず製造し、ナノ粒子を目的とする媒体中に分散させる方法がとられているが、ナノ粒子が凝集して大きな二次粒子を形成しやすいため、煩雑な工程を経る必要がある。本発明では、水不溶性の媒体油と界面活性剤の存在下でマイクロ波処理するだけで、一段でナノサイズ粒子が均一に分散した安定な流体を容易に製造することができる。なお、マイクロ波加熱法は短時間照射でナノ粒子の製造が可能な省エネルギー製造法である。
【００２６】
【図面の簡単な説明】
【図１】実施例１により調製した磁性流体が磁石に吸い寄せられたところを示したものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a simple method for producing a fluid in which inorganic fine particles substantially in a solution state are uniformly dispersed.
[0002]
[Prior art]
BACKGROUND ART Inorganic solid fine powders such as metals and metal oxides have been conventionally used in various fields as industrial materials such as catalysts, magnetic materials and semiconductors. However, if the particle size of these inorganic materials, which had been used on the order of microns, has been reduced to the order of nanometers, new performances with catalytic functions, storage capacities, and lifespans that are several orders of magnitude better than before, or completely different from those of the past. It has been clarified that it exerts its effects, and there is a strong demand for ultrafine powdering or production of fine particles having a small particle size distribution width.
[0003]
Examples of a method for synthesizing such solid fine particles include a solid phase sintering method and a liquid phase reaction method. The solid-state reaction method generally requires a high temperature of around 1000 ° C. In the liquid phase reaction method, the reaction proceeds at a temperature of about 200 ° C. and under pressure (10 to 15 atm). In the liquid phase method, since the crystallization rate is low, a reaction time of several hours to several days is usually required. When this liquid phase reaction is carried out under microwave irradiation, the reaction time can be significantly reduced from several minutes to about one hour, and fine particles having a uniform particle size are generated.
[0004]
[Problems to be solved by the invention]
The ultrafine solid particles generated by the solution method are very likely to aggregate, and the particles are likely to recombine to form coarse secondary particles. Disadvantages are that a large amount of energy is required to disintegrate the agglomerated particles, and that the purity is liable to be reduced due to the incorporation of foreign matter during the disintegration.
[0005]
In the case of producing fine particles by the liquid phase method, first, iron or nickel chloride as a raw material is dissolved in water of a solvent, and a base is added thereto to adjust the pH, and then heated to about 200 ° C. in an autoclave. Crystallize ferrite. The generated ferrite deposits at the lower part of the aqueous phase. This reaction product is collected as a product through filtration, washing, drying and the like. Observation of the generated particles with a transmission electron microscope (TEM) confirms that a large number of primary particles having a diameter of about 10 nanometers are aggregated and bonded in a spherical or bead shape to form secondary particles on the order of microns. Was done.
[0006]
It is very difficult to disintegrate particles in which nano-order fine particles are aggregated, and a great amount of energy is required. Further, when nano-order fine particles are laminated and used, a fluid in which nano-order fine particles are monodispersed is required.
[0007]
[Means for Solving the Problems]
The present inventors have conducted various studies in order to solve problems such as secondary agglomeration in the process of producing inorganic solid fine particles, agglomeration and agglomeration, and secondary contamination during use or contamination during the disintegration. As a result, a monodispersed fluid of nano-sized particles is obtained by adding a base to a mixture of a water-soluble raw material compound for producing fine particles, water, a water-insoluble medium oil and preferably a water-insoluble surfactant, and irradiating the mixture with microwaves. Was found to be.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The water-soluble raw material compound used in the present invention is preferably a water-soluble salt such as chloride, nitrate, sulfate, carbonate and acetate, but oxyhydroxide and alkoxide can also be used. The compounds are not limited to these compounds, and compounds soluble in water can be used.
[0009]
For example, taking Ni ferrite synthesis as an example, predetermined amounts of FeCl ₃ and NiCl ₂ are mixed and dissolved in water, and a water-insoluble medium oil and a surfactant are mixed therein. This water-insoluble medium oil disperses the ferrite fine particles generated by the reaction promptly, suppresses aggregation and grain growth, and stably holds the generated fine particles. As the medium oil, a hydrophobic oil that can be easily separated from the raw material water layer is preferable, and an oil having a lower specific gravity than water is more easily recovered. And the like are particularly preferred medium oils.
[0010]
The surfactant is considered to contribute to stably dispersing and maintaining the formed ferrite fine particles in the medium oil, and is not particularly limited as long as it has this function. For example, surfactants used in various industrial fields can be used in the method of the present invention, but a water-insoluble nonionic surfactant is one particularly preferred example. The mixing ratio of the medium oil, the dispersant, and the raw material aqueous solution is not particularly limited. For example, the addition amount of the medium oil is preferably in a range of about 1/10 to 5 times the volume of the raw water in a volume ratio, and the amount of the surfactant used is about 1/5 volume times or less of the medium oil. Particularly preferred.
[0011]
A required amount of a base is added to a raw material solution prepared by mixing a metal salt aqueous solution, a medium oil, and a surfactant to adjust the pH. As the base, general alkali hydroxide or aqueous ammonia is used, but urea, diamine, or the like, which generates ammonia by thermal decomposition at a high temperature, can also be used.
[0012]
The raw material solution to which the base is added is irradiated and heated with microwaves in a batch or continuous reactor having excellent pressure resistance and good microwave permeability. In the case of Ni ferrite, it is rapidly heated to a predetermined temperature of 100 to 200 ° C., and then maintained at the predetermined temperature for a predetermined time as needed. The frequency of the microwave is usually 2.45 GHz, but is not essentially limited thereto.
[0013]
In a conventional conduction heat transfer heating type hydrothermal reaction, the temperature is transmitted to the inside of the reactor by conduction or convection from the outside of the reactor, so the temperature near the outer wall is high, the temperature inside is low, and very long for crystal growth. Takes time. In the microwave method, it is considered that the heat is applied from the inside by the frictional heat due to the rotation of the polar group, the temperature becomes locally high, and the reaction proceeds rapidly. For example, in the case of ferrite, a reaction that requires several hours to 10 hours at 180 ° C., whereas crystallization is completed in several minutes to one hour at 150 ° C. by the microwave method.
[0014]
In the present invention, solid ferrite fine particles generated by microwave heating move from the raw material aqueous solution phase to the medium oil phase and are stably dispersed. That is, during the preparation of the raw material, an aqueous solution phase containing a ferrite precursor is present in a lower layer, and a water-insoluble medium oil phase in which a surfactant is dissolved is present in an upper layer. When this is irradiated with microwaves, the reaction proceeds in a short time, and ferrite fine particles are generated, float from the lower aqueous phase, move into the upper medium oil, and exhibit a uniform fluid.
[0015]
As a comparative example, when the reaction is performed without adding the medium oil, ferrite fine particles are generated, but the generated fine particles are deposited below the aqueous phase, and a uniform fluid is not generated. Although the true specific gravity of ferrite is 5 or more, a fluid in which ferrite is uniformly dispersed floats on water having a specific gravity of 1. It is presumed that the hydrophilic micelles formed in the medium oil are stabilized by being incorporated into the micelles, and the nanosize is maintained in the micelles.
[0016]
Since the reaction product is uniformly dispersed in the medium oil phase, it can be easily separated and recovered from the raw material aqueous solution phase, and can be repeatedly washed with deionized water.
[0017]
Conventionally, many patents (for example, JP-A-2001-167919, JP-A-10-241928, JP-A-6-69021, etc.) have been disclosed regarding the production of a magnetic fluid in which a magnetic substance is uniformly dispersed in a certain medium liquid. However, in each case, after preparing nanoparticles, they are dispersed as a fluid, and are manufactured through an extremely large number of steps. In the method of the present invention, the production of magnetic material fine particles and the production of magnetic fluid proceed simultaneously, and not only can the process be simplified, but also the secondary growth of particles can be suppressed by the presence of the medium oil in the fine particle generation process. In addition, it is possible to easily produce a nanoparticle-dispersed fluid having a uniform particle size and free from foreign matter.
Hereinafter, the effects of the present invention will be described in more detail with reference to examples.
[0018]
Embodiment 1
1.35 g of FeCl ₃ .6H ₂ O and 0.54 g of NiCl ₂ .6H ₂ O are dissolved in 20 ml of water, to which 20 ml of decane and 1 ml of a water-insoluble surfactant having a sorbitan skeleton and 25 A 3% aqueous ammonia solution was added with stirring to prepare a raw material solution, and the raw material solution was filled in a pressure-resistant reactor made of TFM (trifluorometaxyl) and heated by microwave heating at a frequency of 2.45 GHz. After heating to 150 ° C. and holding at that temperature for 30 minutes, the heating was terminated and immediately cooled to room temperature. The cooled reaction was transferred to a beaker and allowed to stand. As the contents, a lower transparent aqueous phase and an upper black-brown fluid were obtained. The aqueous phase was separated and washed with deionized water to obtain a homogeneous brown fluid. This uniform brown fluid was attracted to the magnet, confirming that it had magnetism. This fluid was a stable fluid without separation even after several months. The fluid is attracted to the magnet as shown in Photo 1.
[0019]
[Comparative Example 1]
The reaction was carried out under the same conditions as in Example 1 except that only decane was not used and 20 ml of water was further added. When the product after the reaction was transferred to a beaker, brown ferrite fine particles were deposited below the transparent aqueous phase.
[0020]
[Comparative Example 2]
Under the same conditions as in Example 1, when no surfactant was added, or when both a decane and a surfactant were not added, an experiment was also performed. As a result, all the brown ferrite particles were deposited only at the bottom and uniformly dispersed. No fluid was obtained. Further, a hydrophilic surfactant was tested under the same conditions, but no fluid ferrite was formed.
[0021]
Embodiment 2
A ferrite production experiment was performed under the same conditions as in Example 1 except that toluene was used as the medium oil. As a result, a uniform fluid ferrite phase floating on the aqueous phase was formed as in Example 1.
[0022]
Embodiment 3
The total amount of the brown fluid obtained in Example 1 and the brown precipitate obtained without using only the surfactant of Comparative Example 2 was filtered through a quantitative filter paper having a pore size of 0.45 μm. As a result, the brown precipitate was filtered off, but the homogeneous fluid passed through the filter paper and could not be filtered off. As a result of X-ray diffraction, it was confirmed that the separated brown precipitate was spinel-type ferrite. As a result of diluting the fluid ferrite and measuring the particle diameter by a scattering method, it was confirmed that the diameter was less than ten and several nanometers.
[0023]
Embodiment 4
The ZrCl ₂ · 8H ₂ O in 1.611g were dissolved in water 20ml, added with stirring thereto and aqueous ammonia 3ml of nonionic surfactant and 25% strength has the sorbitan skeleton of 20ml of decane and 2ml Thus, a raw material solution was prepared. This raw material solution was filled in a pressure-resistant reactor made of TFM, heated to 150 ° C. by microwave heating at a frequency of 2.45 GHz, and maintained at that temperature for 30 minutes. Then, the heating was terminated and the temperature was cooled to room temperature. The whole reaction product after cooling was transferred to a glass beaker and allowed to stand. The contents separated into a lower clear aqueous phase and an upper beige fluid zirconia phase. The upper fluid zirconia homogeneous phase was stable and did not separate after 24 hours.
[0024]
[Comparative Example 3]
As a comparative example, a test was performed under the same conditions as in Example 4 when no surfactant was used or when both a surfactant and decane were not used. In each case, white zirconia fine particles were deposited on the bottom of the transparent aqueous phase, and a uniformly dispersed fluid could not be obtained.
[0025]
【The invention's effect】
In the conventional method, nanoparticles are first produced, and the nanoparticles are dispersed in a target medium.However, since the nanoparticles are easily aggregated to form large secondary particles, a complicated process is required. There is a need. In the present invention, a stable fluid in which nano-sized particles are uniformly dispersed can be easily produced in one step only by microwave treatment in the presence of a water-insoluble medium oil and a surfactant. Note that the microwave heating method is an energy-saving manufacturing method capable of manufacturing nanoparticles by short-time irradiation.
[0026]
[Brief description of the drawings]
FIG. 1 shows a state where a magnetic fluid prepared in Example 1 was attracted to a magnet.

Claims (3)

微粒子製造用水溶性原料化合物、水、水不溶性の媒体油および界面活性剤よりなる混合物に塩基あるいは分解して塩基を供する物質を添加した後、マイクロ波を照射することにより得られる媒体油中に安定分散した無機微粒子分散流体とその製造方法。After adding a base or a substance that decomposes to provide a base to a mixture of a water-soluble raw material compound for producing fine particles, water, a water-insoluble medium oil and a surfactant, the mixture is stable in a medium oil obtained by irradiating microwaves. Dispersed inorganic fine particle dispersion fluid and method for producing the same. 微粒子製造用水溶性原料化合物が、水溶性の無機塩及びアルコキシドなどから選ばれた化合物であることを特徴とする請求項１の無機微粒子分散流体及びその製造方法。2. The inorganic fine particle-dispersed fluid according to claim 1, wherein the water-soluble raw material compound for producing fine particles is a compound selected from a water-soluble inorganic salt and an alkoxide. 界面活性剤が水不溶性であることを特徴とする請求項１及び請求項２の無機微粒子分散流体及びその製造方法。3. The inorganic fine particle-dispersed fluid according to claim 1, wherein the surfactant is water-insoluble, and a method for producing the same.

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