JP4822576B2 - Inorganic hollow powder and method for producing the same - Google Patents
Inorganic hollow powder and method for producing the same Download PDFInfo
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【０００１】
【発明の属する技術分野】
本発明は、無機質中空粉体およびその製造法に関するものである。
【０００２】
【従来技術】
従来、無機質中空体は、軽量材、塗料の充填材、補強用充填材、低誘電率化のための特性改善材、爆薬の増感剤などの様々な用途に用いるために種々の開発が行なわれている。
【０００３】
このような中空粉体として、例えば、ガラス質の中空粉体やアルミナ、ジルコニアなどの中空粉体が知られている。これらの中空粉体は、ガラスなどを高温に加熱溶融して発泡剤によって発泡させながら、粒子状に吹き飛ばして形成される（特公平２−２７２９５号）。また、シラスなどの火山ガラス質堆積物を原料として、中空ガラス球状体を作製すること（特開昭６１−２２２９６９号）等が報告されている。
【０００４】
また、金属炭化物やその前駆体を含む溶液または分散液を微小液滴化し、これを高温雰囲気に微小液滴を噴霧することによって、炭化物からなる微小中空体を形成することが提案されている（特開平６−３２１５２０号）。
【０００５】
【発明が解決しようとする課題】
しかしながら、これらの手法による無機中空体によれば、ガラス質材料を原料とする方法では、ガラス質中に低融点化するために少なからずアルカリ元素を含有しており、また、これらの無機中空粉体の平均粒径は、そのほとんどが３０μｍよりも大きいものであった。そのために、アルカリ元素が水や酸に対して容易に溶出し、耐候性に劣るという欠点があった。しかも、電子部品材料、例えば絶縁基板材料の１成分として混合、複合化することも行なわれているが、このような場合にも、絶縁信頼性が劣化するなどの問題があった。
【０００６】
また、粒子径が３０μｍ以上と大きいと、これを他の材料と複合化することによって軽量化を図る場合、大きな無機中空体が破壊源となるために高強度が要求される構造部材には適用できないものであった。
【０００７】
また、無機質の炭化物を溶媒とともに高温雰囲気中に噴霧する方法は、装置が大がかりになるとともに、溶媒の揮発とともに球状および中空化するために、中空であっても多孔質化しやすく、閉気孔が形成されにくいという問題があった。
【０００８】
また、従来の方法では、中空粉体を形成する無機材料が限定されており、あらゆる無機材料の中空粉体を形成することが難しいものであった。
【０００９】
従って、本発明は、無機中空粉体における上記問題点を解決し、微小粉体からなるとともに内部に閉気孔を具備する無機質中空粉体と、それを簡単な方法で作製することのできる製造方法を提供することを目的とするものである。
【００１０】
【課題を解決するための手段】
本発明者は、上記課題に対して検討を重ねた結果、所定の大きさの有機樹脂球を用いて、球表面に無機化合物、あるいはその前駆体を形成してなる複合体を形成し、この複合体を加熱処理して有機樹脂球を分解除去して無機化合物からなる皮膜を作製した後、さらに所定温度に加熱して前記無機化合物からなる皮膜を緻密化することによって、無機化合物粉体内に閉気孔を具備する中空粉体が得られることを見いだし、本発明に至った。
【００１１】
即ち、本発明の無機質中空粉体は、平均粒径４．６〜２０μｍ、粉体内部の気孔の平均気孔径が０．１〜１５μｍ、閉気孔率が３０体積％以上、ＢＥＴ比表面積が３０ｍ２／ｇ以下であり、結晶質の皮膜を有するとともに、該皮膜の平均厚さが無機質中空粉体の平均粒径の１０．８％以上であることを特徴とするものであって、この中空粉体を形成する無機質材料は、実質的に単一金属酸化物からなっていても、実質的に２種以上の金属酸化物の混合物あるいは化合物からなっていてもよい。また、アルカリ元素の含有率が酸化物換算で５００ｐｐｍ以下であることも大きな特徴である。
【００１２】
また、かかる無機質中空粉体を製造する方法としては、有機樹脂球の表面に無機化合物、あるいはその前駆体を被覆した複合体を形成した後、この複合体を加熱処理して、前記有機樹脂球を分解除去して無機化合物からなる皮膜を作製した後、さらに所定温度に加熱して前記無機化合物からなる結晶質の皮膜を緻密化して、無機化合物粉体内に閉気孔を具備する、平均粒径４．６〜２０μｍ、ＢＥＴ比表面積が３０ｍ ２ ／ｇ以下、前記皮膜の平均厚さが無機質中空粉体の平均粒径の１０．８％以上である中空粉体を形成することを特徴とするものである。
【００１３】
前記無機化合物が、実質的に単一金属酸化物からなっても、実質的に２種以上の金属酸化物の混合物または複合化合物からなってもよい。
【００１４】
【発明の実施の形態】
以下に本発明の無機中空粉体の製造方法について説明する。本発明によれば、まず、有機樹脂球を準備する。この有機樹脂球は最終的に得られる中空粉体における独立平均気孔径を決定する要素であることから、有機樹脂球の大きさとしては、平均粒径が０．１〜１５μｍ、特に２〜５μｍであることが必要である。つまり、０．１μｍよりも小さいと、中空粉体中の閉気孔が小さく、所定の空隙率を達成することが難しく、１５μｍよりも大きいと、微小な中空粉体を形成することが困難となるためである。
【００１５】
次に、この有機樹脂球の表面に無機化合物あるいはその前駆体を被覆する。被覆方法としては、所定の無機化合物のアルコキシド法や沈殿法等の液相を利用して有機樹脂球の表面に無機化合物あるいはその前駆体を析出形成させる手法や、有機樹脂球の表面に、サブミクロンの無機化合物粉末を付着させる手法が挙げられるが、有機樹脂球表面に無機化合物を均一に形成する上で、前者の方が好適である。
【００１６】
その後、得られた複合体を有機樹脂球が分解消失しうる温度、雰囲気下で１次熱処理して、有機樹脂を分解除去することによって、無機化合物のみからなる皮膜内部に空洞を有する見かけ上、中空粉体が形成される。ところが、この段階では、無機化合物からなる皮膜は緻密化されておらず、多孔質からなるために、粉体中の空洞は、閉気孔とはなっておらず、比表面積も大きい状態である。
【００１７】
そこで、本発明によれば、さらに昇温にて２次熱処理を施し、上記処理後の粉体の無機化合物からなる皮膜を緻密化する。この場合の２次熱処理の温度は、無機化合物の組成等に応じて緻密化が進行し得る温度に加熱される。この２次熱処理によって、一次処理後の一次粉体における皮膜の緻密化の進行とともに、粉体の比表面積も次第には小さくなり、緻密な無機化合物からなる皮膜内に閉気孔を有する中空粉体を作製することができる。
【００１８】
なお、本発明の上記の製造方法によれば、有機樹脂球の大きさによって、中空粉体の大きさを任意に定めることができ、有機樹脂球の大きさを平均で０．１〜１５μｍとすることによって、内部の平均気孔径が０．１〜１５μｍであり、平均粒径が２０μｍ以下の微細な中空粉体を作製することができる。また、かかる中空粉体は、閉気孔率が３０％以上、特に４０％以上であることも大きな特徴であって、この閉気孔率が３０％よりも低いと、軽量化等を目的とした部材等に適用した場合に、充分な効果が得られないという問題がある。また、本発明の中空粉体は、無機化合物からなる皮膜が緻密質からなるために、ＢＥＴ比表面積が３０ｍ2／ｇ以下、特に１５ｍ2／ｇ以下であることも大きな特徴である。
【００１９】
しかも、本発明の上記の製造方法においては、有機樹脂球の表面に形成する無機化合物の種類は何ら問うものではなく、有機樹脂球の表面に被覆可能なものであれば、あらゆる無機化合物によって、中空粉体を形成することができることも大きな特徴である。
【００２０】
従って、従来のようなガラスのみならず、あらゆる無機化合物、例えば、ＳｉＯ2、Ａｌ2Ｏ3、ＺｒＯ2、ＺｎＯ、ＢａＯ、ＣａＯ、ＭｇＯ、ＳｒＯの群から選ばれる１種による単一金属化合物、特に酸化物からなる中空粉体を形成することができる。
【００２１】
また、２種以上の金属化合物との混合物あるいは化合物によって中空粉体を形成することもでき、２種以上の混合系では、上記の有機樹脂球を除去した後の熱処理による緻密化処理を低温で行なうことができる。
【００２２】
しかも、本発明の製造方法によれば、ガラスなどの発泡によって形成する場合、必然的にアルカリ金属が含有されるが、本発明によれば、上記のように、あらゆる任意の無機化合物によって中空粉体を形成できるために、アルカリ金属量が５００ｐｐｍ以下、特に３００ｐｐｍ以下とすることができる。
【００２３】
【実施例】
実施例１
テトラメトキシシラン：１０００ｇに対し、平均粒径が０．１５μｍ、２．０μｍ、５．０μｍ、１０．０μｍ、１５．０μｍの単分散アクリル樹脂球をそれぞれ１５０ｇ添加し撹拌しながらさらに水５００ｇを添加して加水分解反応を開始させた。
【００２４】
ゲル化したものを＃１００のナイロンメッシュを用いて粉砕し、２００℃で真空乾燥を行い、さらに振動ミルを用いて粉砕した。この状態の粉体のＢＥＴ比表面積はいずれもほぼ３００ｍ2／ｇであった。作製した粉体を電子顕微鏡にて観察した結果、アクリル樹脂球の表面にシリカゲルが被覆されたものが凝集した状態であった。
【００２５】
得られたこの粉末をアルミナ製るつぼに入れ大気中４５０℃、５時間の条件で保持し、有機樹脂分を完全に分解消失させた。その後、さらに温度を上げ、１０００℃〜１６００℃の温度で１０時間保持して粉体を作製した。
【００２６】
作製した粉体のＢＥＴ比表面積を測定し、また、ピクノメーターによって粉体密度を測定し理論密度で割ることで閉気孔率を計算した。
【００２７】
また、粉体の断面の走査電子顕微鏡写真を観察して、任意に抽出した１０個の粉体中の空隙のうち最大のものを気孔径の平均値とみなした。評価結果を表１に示す。
【００２８】
【表１】
この実施例によれば、熱処理温度が１４００℃よりも低い場合、粉体は多孔質のままで、閉気孔率は０であり、中空粉体にはならなかった。さらに熱処理温度を１４００℃以上に高めた場合、ＢＥＴ比表面積は３０ｍ2／ｇ以下に減少し、同時に閉気孔率が３０体積％以上の中空粉体を作製することができた。
【００３０】
なお、作製した中空粉体について、Ｘ線回折測定を行なって結果、いずれもＳｉＯ2（クオーツ）またはクリストバライトからなる結晶相からなることがわかった。また、ＩＣＰ発光分光分析の結果、この粉体中におけるアルカリ金属の総量は酸化物換算で４０ｐｐｍ以下と非常に少ないものであった。
【００３１】
実施例２
食塩水溶液と、珪酸アルカリ水溶液と、平均粒径５、１０μｍのアクリル樹脂球の混合液にさらに塩酸を加え、ｐＨ６、８０℃に維持し、熟成を行い、アクリル樹脂球の表面にシリカゲルの皮膜を析出させた平均粒径が６μｍおよび１１μｍの複合体を得た。
【００３２】
得られた複合体をアルカリ成分が５００ｐｐｍ以下となるまで酸洗浄した。そして、洗浄後の複合体を、さらにＢ2Ｏ3、ＺｎＯ、ＢａＯ、ＣａＯ、ＺｒＯ2のうちの少なくと１種を含む水溶液に浸漬した後、これを乾燥して有機樹脂球の表面に、シリカゲルと上記金属化合物を被覆した複合体を作製した。
【００３３】
この粉末を大気中、４５０℃で５時間熱処理して有機樹脂分を完全に分解消失させた。そして、８００℃〜１５００℃の温度範囲で熱処理し、実施例１の場合と同様の評価を行った。評価結果を表２、表３に示す。
【００３４】
【表２】
【表３】
熱処理を全く行なわなかった場合（試料Ｎｏ．３１、３７、４３、４９、５５）粉体は多孔質のままであり閉気孔率は０％のままで中空粉体は形成されなかった。また、複合化した酸化物の種類によって中空粉体が形成されるための熱処理温度は様々変化し、ＺｎＯの場合、８００℃以上、ＢａＯ、ＣａＯ，ＺｒＯ2の場合、１５００℃以上、Ｂ2Ｏ3では８５０℃以上での熱処理によって、中空粉体が形成され比表面積３０ｍ2／ｇ以下となり同時に２０体積％以上の閉気孔が形成されたが、Ｂ2Ｏ3の場合、１０００℃よりも温度が高いと、粉体が凝集して閉気孔が形成されなかった。
【００３７】
また、作製した各中空粉体について、Ｘ線回折測定を行なって主結晶相を同定した結果、試料Ｎｏ．３２〜３６、６２〜６６では、クオーツ、試料Ｎｏ．４２、４８、５４、７２、７８、８４ではアモルファス、試料Ｎｏ．５７〜６０、８７〜９０ではクリストバライトの結晶相からなることがわかった。また、ＩＣＰ発光分光分析の結果、この粉体中におけるアルカリ金属の総量は酸化物換算でいずれも３００ｐｐｍ以下と非常に少ないものであった。
【００３８】
実施例３
平均粒径：０．４μｍのＡｌ2Ｏ3と平均粒径：０．４μｍのＺｎＯと、Ａｌ2Ｏ3とＺｎＯの比率が重量比で１００：０、７５：２５、５０：５０、２５：７５、０：１００の５種の比率混合した。そして、この無機化合物と平均粒径が２μｍの有機アクリル樹脂球を無機成分：有機成分＝２：５の体積比率になるように計量し、奈良機械製ハイブリダイザーを用いて混合処理した。処理後の粉末について電子顕微鏡写真で観察した結果、有機樹脂球の表面にＡｌ2Ｏ3とＺｎＯの混合粉末が付着した状態であることがわかった。
【００３９】
この粉末を大気中、４５０℃で５時間熱処理して有機樹脂分を完全に分解消失させた。そして、この複合体を９００℃〜１６００℃の温度範囲で熱処理し、実施例１，２と同様に評価した。評価結果を表４に示す。
【００４０】
【表４】
Ａｌ2Ｏ3：ＺｎＯの比率によって、中空粉体が形成される温度が変化しており、Ａｌ2Ｏ3１００％では１６００℃で、中空粉体が形成された。Ａｌ2Ｏ3：ＺｎＯ＝７５：２５では、１１００℃以上、Ａｌ2Ｏ3：ＺｎＯ＝５０：５０では、１０００℃以上、Ａｌ2Ｏ3：ＺｎＯ＝２５：７５では、１０００℃以上、ＺｎＯ１００％では、１６００℃の加熱温度で、閉気孔率が２０％以上の中空粉体を作製することができた。
【００４２】
また、作製した各中空粉体について、Ｘ線回折測定によって主結晶相の同定を行なった結果、試料Ｎｏ．９５では、Ａｌ2Ｏ3、試料Ｎｏ．９９、１００、１０３〜１０５、１０８〜１１０では、ＺｎＯ・Ａｌ2Ｏ3、試料Ｎｏ．１１５ではＺｎＯが観察された。また、ＩＣＰ発光分光分析の結果、この粉体中におけるアルカリ金属の総量は酸化物換算でいずれも７０ｐｐｍ以下と非常に少ないものであった。
【００４３】
【発明の効果】
以上詳述したように、本発明によれば有機樹脂球の表面に無機成分を析出あるいは付着させ、加熱によって有機樹脂球を分解除去した後、さらに加熱することで種々の組成の閉気孔を有する無機質中空粉体を容易に作製することが可能となる。また、アルカリ元素を実質的に含まないため様々な用途への適応が可能となる。しかも、空孔径および隔壁の厚さについても自由に設計することが可能であるために構造材料への適用においても強度劣化などの問題発生を防ぐことができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inorganic hollow powder and a method for producing the same.
[0002]
[Prior art]
Conventionally, inorganic hollow bodies have been developed for use in various applications such as lightweight materials, paint fillers, reinforcing fillers, property improving materials for lowering dielectric constants, and explosive sensitizers. It is.
[0003]
As such a hollow powder, for example, a glassy hollow powder or a hollow powder such as alumina or zirconia is known. These hollow powders are formed by blowing glass into particles while melting glass or the like at high temperature and foaming with a foaming agent (Japanese Patent Publication No. 2-27295). Further, it has been reported that hollow glass spheres are produced using volcanic glassy deposits such as shirasu (Japanese Patent Laid-Open No. 61-222969).
[0004]
In addition, it has been proposed to form a micro hollow body made of carbide by making a solution or dispersion containing a metal carbide or its precursor into micro droplets and spraying the micro droplets in a high temperature atmosphere ( JP-A-6-321520).
[0005]
[Problems to be solved by the invention]
However, according to the inorganic hollow body by these methods, the method using a vitreous material as a raw material contains not only an alkali element in order to lower the melting point in the vitreous, and these inorganic hollow powders Most of the average particle size of the body was larger than 30 μm. For this reason, there is a drawback that the alkali element is easily eluted with respect to water and acid, and the weather resistance is poor. Moreover, mixing and compounding as a component of an electronic component material, for example, an insulating substrate material, is also performed, but in this case, there is a problem that the insulation reliability deteriorates.
[0006]
In addition, when the particle size is as large as 30 μm or more, it is applied to a structural member that requires high strength because a large inorganic hollow body is a source of destruction when reducing the weight by combining it with other materials. It was impossible.
[0007]
In addition, the method of spraying inorganic carbide together with a solvent in a high-temperature atmosphere is a large-scale device, and since it becomes spherical and hollow as the solvent evaporates, it is easy to be porous even if it is hollow, and closed pores are formed. There was a problem that it was difficult to be done.
[0008]
Further, in the conventional method, the inorganic material for forming the hollow powder is limited, and it is difficult to form the hollow powder of any inorganic material.
[0009]
Therefore, the present invention solves the above-mentioned problems in the inorganic hollow powder, and comprises an inorganic hollow powder comprising a fine powder and having closed pores therein, and a production method capable of producing the same by a simple method. Is intended to provide.
[0010]
[Means for Solving the Problems]
As a result of studying the above problems, the present inventor formed a composite formed by forming an inorganic compound or a precursor thereof on the sphere surface using organic resin spheres of a predetermined size. The composite is heat-treated to decompose and remove the organic resin spheres to produce a film made of an inorganic compound, and further heated to a predetermined temperature to densify the film made of the inorganic compound, so that the inorganic compound powder is contained in the powder. The inventors have found that a hollow powder having closed pores can be obtained, and have reached the present invention.
[0011]
That is, inorganic hollow powder of the present invention has an average particle diameter of 4.6 to 20 [mu] m, pores of an average pore diameter of 0.1~15μm powder body portion, closed porosity is 30 vol% or more, a BET specific surface area and a 30 m 2 / g or less, and having a coating of crystalline, there is an average thickness of said coating, characterized in der Rukoto 10.8% or more of the average particle size of the inorganic hollow powder, The inorganic material forming the hollow powder may consist essentially of a single metal oxide, or may consist essentially of a mixture or compound of two or more metal oxides. Another major feature is that the alkali element content is 500 ppm or less in terms of oxide.
[0012]
In addition, as a method for producing such an inorganic hollow powder, the organic resin sphere is formed by forming a complex on the surface of the organic resin sphere with an inorganic compound or a precursor thereof, and then heating the complex. after producing a film made of an inorganic compound to decompose and remove, and further densify the crystalline film comprising the inorganic compound is heated to a predetermined temperature, comprising a closed pore inorganic compound powder body, the average particle size A hollow powder having a thickness of 4.6 to 20 μm, a BET specific surface area of 30 m 2 / g or less, and an average thickness of the film being 10.8% or more of the average particle diameter of the inorganic hollow powder is formed. Is.
[0013]
The inorganic compound may consist essentially of a single metal oxide, or may consist essentially of a mixture or composite compound of two or more metal oxides.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Below, the manufacturing method of the inorganic hollow powder of this invention is demonstrated. According to the present invention, first, an organic resin sphere is prepared. Since this organic resin sphere is an element that determines the independent average pore diameter in the finally obtained hollow powder, the average particle diameter of the organic resin sphere is 0.1 to 15 μm, particularly 2 to 5 μm. It is necessary to be. That is, if it is smaller than 0.1 μm, closed pores in the hollow powder are small and it is difficult to achieve a predetermined porosity, and if it is larger than 15 μm, it is difficult to form a fine hollow powder. Because.
[0015]
Next, the surface of the organic resin sphere is coated with an inorganic compound or a precursor thereof. As a coating method, a method of depositing an inorganic compound or a precursor thereof on the surface of an organic resin sphere by using a liquid phase such as an alkoxide method or a precipitation method of a predetermined inorganic compound, Although the technique of attaching a micron inorganic compound powder is mentioned, the former is more suitable for uniformly forming an inorganic compound on the surface of the organic resin sphere.
[0016]
Thereafter, the resulting composite is subjected to a primary heat treatment in an atmosphere at which the organic resin spheres can decompose and disappear, and the organic resin is decomposed and removed, thereby apparently having cavities inside the film made of only an inorganic compound. A hollow powder is formed. However, at this stage, the film made of the inorganic compound is not densified and is porous, so that the voids in the powder are not closed pores and have a large specific surface area.
[0017]
Therefore, according to the present invention, a secondary heat treatment is further performed at an elevated temperature to densify the film made of the inorganic compound in the powder after the above treatment. The temperature of the secondary heat treatment in this case is heated to a temperature at which densification can proceed according to the composition of the inorganic compound. With this secondary heat treatment, as the film density of the primary powder after the primary treatment progresses, the specific surface area of the powder gradually decreases, and a hollow powder having closed pores in the film made of a dense inorganic compound is formed. Can be produced.
[0018]
In addition, according to said manufacturing method of this invention, the magnitude | size of hollow powder can be arbitrarily defined with the magnitude | size of an organic resin sphere, and the magnitude | size of an organic resin sphere is 0.1-15 micrometers on average By doing so, it is possible to produce a fine hollow powder having an internal average pore diameter of 0.1 to 15 μm and an average particle diameter of 20 μm or less. In addition, such a hollow powder is also characterized in that the closed porosity is 30% or more, particularly 40% or more. When this closed porosity is lower than 30%, a member intended for weight reduction or the like. When applied to the above, there is a problem that a sufficient effect cannot be obtained. In addition, the hollow powder of the present invention is also characterized by a BET specific surface area of 30 m 2 / g or less, particularly 15 m 2 / g or less because the film made of an inorganic compound is dense.
[0019]
Moreover, in the above production method of the present invention, the kind of inorganic compound formed on the surface of the organic resin sphere is not questioned, and any inorganic compound can be used as long as it can be coated on the surface of the organic resin sphere. It is also a great feature that a hollow powder can be formed.
[0020]
Therefore, not only conventional glass but also any inorganic compound, for example, a single metal compound selected from the group consisting of SiO 2 , Al 2 O 3 , ZrO 2 , ZnO, BaO, CaO, MgO, SrO, In particular, a hollow powder made of an oxide can be formed.
[0021]
In addition, a hollow powder can be formed by a mixture or a compound with two or more kinds of metal compounds. In the case of two or more kinds of mixed systems, densification treatment by heat treatment after removing the organic resin spheres can be performed at a low temperature. Can be done.
[0022]
Moreover, according to the production method of the present invention, when formed by foaming of glass or the like, an alkali metal is inevitably contained, but according to the present invention, as described above, the hollow powder is formed by any arbitrary inorganic compound. In order to form a body, the amount of alkali metal can be 500 ppm or less, particularly 300 ppm or less.
[0023]
【Example】
Example 1
Tetramethoxysilane: 150 g of monodisperse acrylic resin spheres with an average particle size of 0.15 μm, 2.0 μm, 5.0 μm, 10.0 μm, and 15.0 μm were added to 1000 g, and 500 g of water was further added while stirring. Then, the hydrolysis reaction was started.
[0024]
The gelled product was pulverized using a # 100 nylon mesh, vacuum dried at 200 ° C., and further pulverized using a vibration mill. The BET specific surface area of the powder in this state was almost 300 m 2 / g. As a result of observing the produced powder with an electron microscope, the surface of the acrylic resin sphere coated with silica gel was in an aggregated state.
[0025]
The obtained powder was put in an alumina crucible and kept in the atmosphere at 450 ° C. for 5 hours to completely decompose and disappear the organic resin. Thereafter, the temperature was further raised and held at a temperature of 1000 ° C. to 1600 ° C. for 10 hours to produce a powder.
[0026]
The BET specific surface area of the produced powder was measured, the powder density was measured with a pycnometer, and the closed porosity was calculated by dividing by the theoretical density.
[0027]
Further, a scanning electron micrograph of the cross section of the powder was observed, and the largest one of the voids in the arbitrarily extracted ten powders was regarded as the average value of the pore diameter. The evaluation results are shown in Table 1.
[0028]
[Table 1]
According to this example, when the heat treatment temperature was lower than 1400 ° C., the powder remained porous, the closed porosity was 0, and did not become a hollow powder. Further, when the heat treatment temperature was increased to 1400 ° C. or higher, the BET specific surface area decreased to 30 m 2 / g or lower, and at the same time, a hollow powder having a closed porosity of 30 volume% or higher could be produced.
[0030]
The produced hollow powder was subjected to X-ray diffraction measurement, and as a result, it was found that both were composed of a crystal phase composed of SiO 2 (quartz) or cristobalite. Further, as a result of ICP emission spectroscopic analysis, the total amount of alkali metals in the powder was very low at 40 ppm or less in terms of oxide.
[0031]
Example 2
Hydrochloric acid is further added to a mixed solution of a saline solution, an alkali silicate solution, and acrylic resin spheres having an average particle size of 5 and 10 μm, and maintained at pH 6 and 80 ° C., followed by aging, and a silica gel film is formed on the surface of the acrylic resin spheres. Precipitated composites with average particle sizes of 6 μm and 11 μm were obtained.
[0032]
The obtained composite was acid washed until the alkali component was 500 ppm or less. Then, the washed composite is further immersed in an aqueous solution containing at least one of B 2 O 3 , ZnO, BaO, CaO, and ZrO 2 , and then dried to the surface of the organic resin sphere. A composite coated with silica gel and the above metal compound was prepared.
[0033]
This powder was heat-treated in the atmosphere at 450 ° C. for 5 hours to completely decompose and disappear the organic resin component. And it heat-processed in the temperature range of 800 to 1500 degreeC, and performed the same evaluation as the case of Example 1. FIG. The evaluation results are shown in Tables 2 and 3.
[0034]
[Table 2]
[Table 3]
When no heat treatment was performed (Sample Nos. 31, 37, 43, 49, and 55), the powder remained porous, the closed porosity remained at 0%, and no hollow powder was formed. Further, the heat treatment temperature for forming the hollow powder varies depending on the type of the composite oxide. In the case of ZnO, it is 800 ° C. or higher, in the case of BaO, CaO, ZrO 2 , 1500 ° C. or higher, B 2 O In No. 3 , a hollow powder was formed by heat treatment at 850 ° C. or more and the specific surface area was 30 m 2 / g or less, and simultaneously 20% by volume or more closed pores were formed. In the case of B 2 O 3 , the temperature was higher than 1000 ° C. When it was high, the powder aggregated and closed pores were not formed.
[0037]
Further, as a result of performing X-ray diffraction measurement and identifying the main crystal phase for each of the produced hollow powders, the sample No. In 32 to 36 and 62 to 66, quartz, sample No. 42, 48, 54, 72, 78, 84, amorphous, sample No. It was found that 57-60 and 87-90 consisted of a crystal phase of cristobalite. Further, as a result of ICP emission spectroscopic analysis, the total amount of alkali metals in the powder was very small at 300 ppm or less in terms of oxide.
[0038]
Example 3
Average particle diameter: 0.4 μm Al 2 O 3 and average particle diameter: 0.4 μm ZnO, and the ratio of Al 2 O 3 and ZnO is 100: 0, 75:25, 50:50, 25: Five ratios of 75, 0: 100 were mixed. Then, the inorganic compound and organic acrylic resin spheres having an average particle diameter of 2 μm were weighed so as to have a volume ratio of inorganic component: organic component = 2: 5, and mixed using a hybridizer manufactured by Nara Machinery. As a result of observing the treated powder with an electron micrograph, it was found that a mixed powder of Al 2 O 3 and ZnO adhered to the surface of the organic resin sphere.
[0039]
This powder was heat-treated in the atmosphere at 450 ° C. for 5 hours to completely decompose and disappear the organic resin component. And this composite_body | complex was heat-processed in the temperature range of 900 to 1600 degreeC, and evaluated similarly to Example 1,2. The evaluation results are shown in Table 4.
[0040]
[Table 4]
The temperature at which the hollow powder was formed was changed depending on the ratio of Al 2 O 3 : ZnO, and the hollow powder was formed at 1600 ° C. with 100% Al 2 O 3 . In Al 2 O 3 : ZnO = 75: 25, 1100 ° C. or higher, Al 2 O 3 : ZnO = 50: 50, 1000 ° C. or higher, Al 2 O 3 : ZnO = 25: 75, 1000 ° C. or higher, ZnO 100% Then, it was possible to produce a hollow powder having a closed porosity of 20% or more at a heating temperature of 1600 ° C.
[0042]
Further, as a result of identifying the main crystal phase by X-ray diffraction measurement for each of the produced hollow powders, the sample No. 95, Al 2 O 3 , Sample No. 99, 100, 103-105, 108-110, ZnO.Al 2 O 3 , Sample No. In 115, ZnO was observed. Further, as a result of ICP emission spectroscopic analysis, the total amount of alkali metals in the powder was very small at 70 ppm or less in terms of oxide.
[0043]
【The invention's effect】
As described above in detail, according to the present invention, inorganic components are deposited or adhered on the surface of the organic resin spheres, and the organic resin spheres are decomposed and removed by heating, and then heated to have closed pores of various compositions. It becomes possible to easily produce an inorganic hollow powder. Further, since it does not substantially contain an alkali element, it can be applied to various applications. In addition, since the pore diameter and the partition wall thickness can be freely designed, problems such as strength deterioration can be prevented even when applied to a structural material.
Claims (7)
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| DE10226131A1 (en) * | 2002-06-12 | 2003-12-24 | Studiengesellschaft Kohle Mbh | Thermally stable materials with a high specific surface |
| DE10342600B4 (en) * | 2003-09-12 | 2009-04-09 | H.C. Starck Gmbh | Valve metal oxide powder and process for its preparation |
| JP4654428B2 (en) * | 2004-03-18 | 2011-03-23 | 国立大学法人 名古屋工業大学 | Highly dispersed silica nano hollow particles and method for producing the same |
| JP5241994B2 (en) | 2004-11-05 | 2013-07-17 | 戸田工業株式会社 | Titanium oxide particle powder and photocatalyst |
| WO2007125891A1 (en) * | 2006-04-24 | 2007-11-08 | Denki Kagaku Kogyo Kabushiki Kaisha | Inorganic hollow particle, process for producing the same, and composition containing the same |
| JP5077922B2 (en) * | 2006-10-31 | 2012-11-21 | 独立行政法人物質・材料研究機構 | Core / shell structure, hollow shell structure, and manufacturing method thereof |
| JP5364276B2 (en) * | 2008-02-28 | 2013-12-11 | 花王株式会社 | Hollow silica particles and method for producing the same |
| JP5499442B2 (en) * | 2008-04-10 | 2014-05-21 | 株式会社豊田中央研究所 | Metal oxide encapsulated mesoporous silica capsule |
| JP5279608B2 (en) * | 2009-05-18 | 2013-09-04 | 株式会社Ａｄｅｋａ | Hybrid fine particles and method for producing the same |
| JP5762120B2 (en) * | 2010-05-11 | 2015-08-12 | 日揮触媒化成株式会社 | Method for producing silica-based particles |
| JP6255053B2 (en) * | 2016-04-20 | 2017-12-27 | 花王株式会社 | Hollow silica particles and method for producing the same |
| JP6975575B2 (en) * | 2017-08-04 | 2021-12-01 | 太平洋セメント株式会社 | Oxide hollow particles |
| IL302478A (en) | 2017-09-11 | 2023-06-01 | Harvard College | Porous metal oxide microspheres |
| WO2019051357A1 (en) | 2017-09-11 | 2019-03-14 | President And Fellows Of Harvard College | Microspheres comprising polydisperse polymer nanospheres and porous metal oxide microspheres |
| JP7433022B2 (en) * | 2019-11-13 | 2024-02-19 | 日鉄ケミカル＆マテリアル株式会社 | Hollow silica particles, their manufacturing method, resin composite compositions and resin composites using the same |
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| JPS58120525A (en) * | 1982-01-05 | 1983-07-18 | Asahi Glass Co Ltd | Manufacture of hollow silicate sphere |
| JPS58223606A (en) * | 1982-06-14 | 1983-12-26 | Nippon Soda Co Ltd | Preparation of ultrafine hollow microsphere of metallic oxide |
| JPS61174145A (en) * | 1985-01-29 | 1986-08-05 | Fuji Debuison Kagaku Kk | Production of hollow spherical glass body |
| JPS63229140A (en) * | 1987-03-18 | 1988-09-26 | Nippon Shokubai Kagaku Kogyo Co Ltd | Production of mineral hollow spherical particle |
| US5077241A (en) * | 1988-11-17 | 1991-12-31 | Minnesota Mining And Manufacturing Company | Sol gel-derived ceramic bubbles |
| JPH02225327A (en) * | 1989-02-23 | 1990-09-07 | Nippon Muki Kk | Production of filler for sealing material and hollow spherical silica glass |
| JPH05138009A (en) * | 1991-11-22 | 1993-06-01 | Japan Synthetic Rubber Co Ltd | Production of spherical inorganic hollow particles |
| JP3265653B2 (en) * | 1992-11-12 | 2002-03-11 | ジェイエスアール株式会社 | Composite particles, hollow particles and their production method |
| JPH0796165A (en) * | 1992-12-11 | 1995-04-11 | Asahi Glass Co Ltd | Production of crystalline fine hollow body and crystalline fine hollow body |
| JP3400548B2 (en) * | 1993-06-29 | 2003-04-28 | 三菱レイヨン株式会社 | Method for producing high-purity spherical silica |
| JPH07265686A (en) * | 1994-03-29 | 1995-10-17 | Kansai Shin Gijutsu Kenkyusho:Kk | Particles uniform in particle diameter and production thereof |
| FR2747669B1 (en) * | 1996-04-22 | 1998-05-22 | Rhone Poulenc Chimie | PROCESS FOR THE PREPARATION OF HOLLOW SILICA PARTICLES |
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