JP4970245B2 - Method for recovering encapsulated substances and novel microspheres obtainable by the method - Google Patents

Description

  The present invention relates to a method for recovering an encapsulated substance from microspheres composed of an outer shell made of a thermoplastic resin and an encapsulated substance contained therein, and a novel microsphere that can be obtained by carrying out the method.

In recent years, regulations on chemical substances have been strengthened, and recycling of resources from used electrical appliances and automobiles has been demanded, as well as collection of substances and useful substances that affect the natural environment.
In particular, Freon gas (chlorofluorocarbon) is a substance that causes destruction of the ozone layer and global warming. When it is released into the atmosphere and reaches the stratosphere, it is decomposed by the strong ultraviolet rays from the sun, and the chlorine radicals generated in this process are It destroys the ozone layer, creates ozone holes, and worsens the environmental state of the stratosphere. In addition, chlorofluorocarbons that remain in the troposphere of the earth are not decomposed because they are stable compounds that are very difficult to decompose, cause a greenhouse effect similar to carbon dioxide, promote global warming, and are suitable for living organisms. Deteriorate the global environment. Therefore, the release of chlorofluorocarbon gas into the atmosphere has a tremendous impact on all the creatures on earth and humanity.
Currently, the recovery of CFCs has become a global issue to be addressed by mankind, and technology for recovering CFCs from resin materials containing CFCs as foaming agents has attracted attention.
For example, in Patent Document 1, a crushed material in which a fragment of a thermosetting foamed urethane resin containing a fluorocarbon gas and a thermoplastic resin is mixed is supplied to a vent-type extruder, and the crushed material is finely crushed or melted in a barrel. After collecting the CFC gas separated from the crushed material at the vent, the crushed material from which the CFC gas has been removed is pushed out from the nozzle connected to the barrel, and the separated CFC gas is separated from the CFC gas by a separator connected to the vent section. A method for recovering chlorofluorocarbon gas is disclosed.
Further, in Patent Document 2, the outer plate or inner plate of a heat insulating box such as a refrigerator filled with a foam heat insulating material is peeled off, and the foam heat insulating material is peeled off from the outer plate or the inner plate while being crushed by the peeling device. The exfoliated material used in the above and the exfoliated foam insulation were separated by a separation device, and the separated foam insulation was pulverized by a pulverization device to release the chlorofluorocarbon enclosed in the bubbles inside. A method is disclosed in which chlorofluorocarbon is liquefied and recovered by a chlorofluorocarbon recovery device to recover chlorofluorocarbon gas in the foam insulation.
All of these methods require a large-scale apparatus because chlorofluorocarbon is recovered using physical means such as pulverization and melting. In addition, due to the nature of the device, it is difficult to maintain airtightness, and there is a problem that a high recovery rate cannot be expected.
As one of the resin materials containing the foaming agent mentioned above, a thermally expandable microcapsule is known, and has a structure in which a thermoplastic resin is used as an outer shell and an inclusion substance as a foaming agent is enclosed therein. ing. When such a heat-expandable microcapsule is heated, part or all of the encapsulated substance is vaporized and the volume of the encapsulated substance is expanded, and an outer shell softened by heating is generated by the volume expansion of the encapsulated substance. By pressure, it is pushed outward and light hollow particles are obtained.
Patent Document 3 discloses a novel thermally expandable microcapsule that eliminates the disadvantages of Freon gas. This heat-expandable microcapsule is characterized by containing, as a foaming agent, a fluorine-containing ether compound having a small environmental load instead of CFC gas.
JP 2002-192524 A JP 2000-102923 A International Publication No. 2004/074396 Pamphlet

  Since fluorine-containing ether compounds are more expensive than Freon gas, recovery and reuse are desired from the viewpoint of resource recycling. Conventionally, it has not been considered that encapsulated substances encapsulated in thermally expandable microcapsules or hollow particles have a great influence on the natural environment. However, now that volatile organic compounds (VOC) are listed as causative substances for urban air pollution, regulations on the collection and reuse of substances that are suspected of having a slight adverse effect on the global environment may be enacted. I cannot deny sex. For these reasons, there is an urgent need to establish a recovery method for any type of inclusion material.

An object of the present invention is to provide a method for easily and efficiently recovering an encapsulated substance from a microsphere composed of an outer shell made of a thermoplastic resin and an encapsulated substance contained therein. Another object of the present invention is to provide a novel microsphere that can be obtained after the inclusion substance is recovered.
When the methods disclosed in Patent Documents 1 and 2 are applied to microspheres, the apparatus is large and difficult to operate, a high recovery rate of encapsulated substances cannot be expected, and physics that consumes a large amount of energy such as pulverization and melting Problems such as the need for an appropriate means are expected.
As a result of various investigations with these problems in mind, the present inventors have (1) the fine spheres are already fine particles, and the surface area is wide, so that the microspheres are brought into contact with the solvent. , Using the concentration gradient without damaging the outer shell, efficiently moving the encapsulated material inside the outer shell to the solvent outside the outer shell and recovering it. (2) The microspheres that can be obtained after recovery are new microspheres. The present inventors have found that it is a sphere and have reached the present invention.
That is, the method for recovering an encapsulated substance according to the present invention comprises a microsphere composed of an outer shell made of a thermoplastic resin, an encapsulated substance encapsulated in the outer shell and having a boiling point lower than the softening point of the thermoplastic resin, and a solvent. It is a method including the contact process which contacts. The method for recovering an encapsulated substance of the present invention is preferably a method further including a separation step of recovering the encapsulated substance from the mixture obtained in the contact step, and more preferably when the separation step is performed together with the contact step.
The novel microsphere according to the present invention can be obtained after the contacting step in the method for recovering an inclusion substance, and the thermoplastic resin is used as an outer shell.

（式中、ｓは粒子径の標準偏差、＜ｘ＞は平均粒子径、ｘ_ｉはｉ番目の粒子径、ｎは粒子の数である。）
熱膨張性微小球は、外殻および内包物質以外の成分によって付加や修飾等されたものであってもよい。たとえば、熱膨張性微小球においてその外殻の外表面に微粒子充填剤を付着させて用いることが、使用時における分散性の向上及び流動性改善の観点から、好ましい。
微粒子充填剤は、有機系及び無機系充填剤のいずれでもよく、その種類及び量は、使用目的に応じて適宜選定される。
有機系充填剤としては、たとえば、ステアリン酸マグネシウム、ステアリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸バリウム、ステアリン酸リチウム等の金属セッケン類；ポリエチレンワックス、ラウリン酸アミド、ミリスチン酸アミド、パルミチン酸アミド、ステアリン酸アミド、硬化ひまし油等の合成ワックス類；ポリアクリルアミド、ポリイミド、ナイロン、ポリメタクリル酸メチル、ポリエチレン、ポリテトラフルオロエチレン等の樹脂粉体等が挙げられる。
無機系充填剤としては、層状構造を有するもの、たとえば、タルク、マイカ、ベントナイト、セリサイト、カーボンブラック、二硫化モリブデン、二硫化タングステン、弗化黒鉛、弗化カルシウム、窒化ホウ素等；その他、シリカ、アルミナ、雲母、炭酸カルシウム、水酸化カルシウム、リン酸カルシウム、水酸化マグネシウム、リン酸マグネシウム、硫酸バリウム、二酸化チタン、酸化亜鉛、セラミックビーズ、ガラスビーズ、水晶ビーズ等が挙げられる。
これらの微粒子充填剤は、１種または２種以上を併用してもよい。
外殻の外表面に付着する微粒子充填剤は、上記のうち、融点９０℃以上（好ましくは１００℃以上、より好ましくは１１０℃以上、さらに好ましくは１２０℃以上、特に好ましくは１５０℃以上、最も好ましくは２００℃以上の融点を有する）の有機化合物又は層状構造を有する無機化合物（好ましくはカーボンブラック、二硫化モリブデン、二硫化タングステン、弗化黒鉛および窒化ホウ素から選ばれた少なくとも１種）、つまり、熱融着防止剤であることが好ましい。ここで、熱融着防止剤は、熱膨張性微小球および／または熱膨張した微小球の外殻樹脂の熱融着を防止し、さらに、加熱膨張時にも隣接する熱膨張性微小球および／または熱膨張した微小球との熱融着を防止し、発泡性能を損なわない働きをするものとする。これにより、例えば、熱膨張性微小球を膨張させて得られ、再膨張できる余力を有する熱膨張した微小球を、タイヤとリムとの組立体内部に充填した場合、タイヤが受傷してタイヤ内圧が低下したとしても、速やかにタイヤ受傷部を封止し、高いタイヤ内圧付与機能を発揮させることができ、その結果、受傷したタイヤでも、必要な距離を走行させることができる。この効果は、特に、発泡剤が含弗素化合物を含む場合に顕著である。
また、ニトリル系単量体とカルボキシル基含有単量体とを必須成分として含む単量体混合物を重合して得られる熱可塑性樹脂を外殻に用いた熱膨張性微小球の場合には、耐熱性、難燃（不燃）性において良好な性能を発揮させることができるとともに、熱膨張性微小球を膨張させて得られ、再膨張できる余力を有する熱膨張した微小球に対して、９０℃以上（好ましくは１００℃以上、さらに好ましくは１２０℃以上）の温度で再膨張開始させることができ、上記効果が顕著となる。
微粒子充填剤の平均粒子径は、付着前の熱膨張性微小球の平均粒子径の１／１０以下であることが好ましい。ここで、平均粒子径とは、一次粒子における平均粒子径を意味する。
熱膨張性微小球への微粒子充填剤の付着量は、特に限定はないが、微粒子充填剤による機能を十分に発揮でき、熱膨張性微小球の真比重の大きさ等を考慮すると、付着前の熱膨張性微小球に対して好ましくは０．１〜９５重量％、さらに好ましくは０．５〜６０重量％、特に好ましくは５〜５０重量％、最も好ましくは８〜３０重量％である。
熱膨張性微小球の外表面への微粒子充填剤の付着は、熱膨張性微小球と微粒子充填剤とを混合することによって行うことができる。混合については、特に限定はなく、容器と攪拌バネといった極めて簡単な機構を備えた装置を用いて行うことができる。また、一般的な揺動または攪拌を行える粉体混合機を用いてもよい。粉体混合機としては、たとえば、リボン型混合機、垂直スクリュー型混合機等の揺動攪拌または攪拌を行える粉体混合機を挙げることができる。また、近年、攪拌装置を組み合わせたことにより効率のよい多機能な粉体混合機であるスーパーミキサー（株式会社カワタ製）及びハイスピードミキサー（株式会社深江製）、ニューグラムマシン（株式会社セイシン企業製）等を用いてもよい。
なお、熱膨張性微小球は、例えば、そのままタイヤとリムとの組立体内部に充填し、熱膨張性微小球の膨張開始温度以上の温度で加熱することにより膨張させて、体積保持材として使用することができる。また、そのまま、自動車等の塗料の軽量化充填剤、壁紙や衣服装飾用の発泡インク用発泡粒子、樹脂組成物軽量化のための発泡材等の用途に使用してもよい。
次に、熱膨張した微小球について説明する。
ｂ．熱膨張した微小球
熱膨張した微小球は、上記で説明した熱膨張性微小球を熱膨張させて得られる。熱膨張した微小球を製造する方法については、熱膨張性微小球を加熱して熱膨張させる工程を含む製造方法であれば特に限定はなく、従来公知の方法を適用することができるが、なかでも、以下に示す２つの方法を好ましい方法として挙げることができる。
（Ａ）上記で説明した熱膨張性微小球（原料）を含む気体流体を、出口に分散ノズルを備え且つ熱風流の内側に設置された気体導入管に流し、前記分散ノズルから噴射させる工程（噴射工程）と、前記気体流体を前記分散ノズルの下流部に設置された衝突板に衝突させ、熱膨張性微小球を前記熱風気流中に分散させる工程（分散工程）と、分散した熱膨張性微小球を前記熱風気流中で膨張開始温度以上に加熱して膨張させる工程（膨張工程）とを含む製造方法。
（Ｂ）上記で説明した熱膨張性微小球（原料）を含む気体流体を、出口に分散ノズルを備え且つ熱風流の外部に設置された少なくとも１つの気体導入管に流し、前記分散ノズルから噴射させ、熱膨張性微小球を前記熱風流中に分散させる工程（分散工程）と、分散した熱膨張性微小球を前記熱風流中で膨張開始温度以上に加熱して膨張させる工程（膨張工程）とを含む製造方法。
上記製造方法においては、エネルギー効率が高く、温度制御が容易で、原料であるどの熱膨張性微小球に対してもほぼ同一の熱履歴を連続的に与えることができ、気流中での分散性が高い。このため、膨張前後における粒度分布の変動係数の変化が小さく、得られた熱膨張した微小球の品質（特に、粒子径分布および真比重の分布）の均一性が高い。すなわち、得られた熱膨張した微小球に含まれる凝集微小球の生成をできるだけ抑制することができ、しかも、原料やわずかに膨張した微小球の含有率を極めて小さくすることができる。
また、上記の製造方法において、膨張条件を制御することによって、得られる熱膨張した微小球が再膨張開始温度を有するようにも、有しないようにもすることができる。なお、微小球が再膨張開始温度を有するとは、一旦製造された熱膨張した微小球がなお熱膨張する性質を有しており、熱膨張した微小球を加熱すると、再び加熱膨張する現象が見られることを意味する。そして、その加熱膨張し始める温度を再膨張開始温度と称する。また、熱膨張した微小球が再膨張開始温度を有することは、最大（再）膨張温度における膨張倍率が１００％超であることと同義である。一方、微小球が再膨張開始温度を有しないとは、微小球がほぼ完全に熱膨張したことを意味する。
膨張条件の制御については、特に限定はない。たとえば、まず、原料供給量、熱風流量や原料分散気体量等のパラメーターを一定に固定し、熱風流の温度（以下、「熱風温度」ということがある。）を変化させる。次に、熱風温度を段階的に変化させ、かつ、他のパラメーターを一定に固定しながら各温度で原料微小球を膨張させ、得られた微小球の真比重を測定し、熱風温度（ｘ軸）と真比重（ｙ軸）の関係をプロットしたグラフを作成する。このグラフにおいて、最低真比重（グラフにおける極小値）に対応する温度領域を熱風温度に設定することによって、得られる熱膨張した微小球が再膨張開始温度を有しないように製造することができる。
また、所望の真比重を有する膨張した微小球を製造する場合は、そのグラフにおいて所望の真比重に対応する熱風温度に設定する。これにより、膨張条件の制御が行われ、所望の再膨張できる余力を有する熱膨張した微小球を製造することができる。
さらに、原料供給量および／または原料分散気体量を変化させる場合、熱風気流により供給される熱量や原料である熱膨張性微小球の全熱容量等を考慮して、熱風温度等を変化させて、膨張条件を制御する。例えば、原料供給量および原料分散気体量を増加させる場合は、熱風温度を上げる。原料供給量および原料分散気体量を減少させる場合は、熱風温度を低くする。
上記製造方法においては、エネルギー効率が高く、温度制御が容易で、原料であるどの熱膨張性微小球に対してもほぼ同一の熱履歴を連続的に与えることができ、気流中での分散性が高い。このため、膨張前後における粒度分布の変動係数の変化が小さく、得られた熱膨張した微小球の品質（特に、粒子径分布および真比重の分布）の均一性が高い。すなわち、得られた熱膨張した微小球に含まれる凝集微小球の生成をできるだけ抑制することができ、しかも、原料やわずかに膨張した微小球の含有率を極めて小さくすることができる。
このようにして得られた熱膨張した微小球は、たとえば、ランフラットタイヤの主要部材として利用できる。すなわち、タイヤとリムとの組立体内部に熱膨張した微小球を充填することにより、タイヤが受傷して、タイヤ内圧が低下した際に、タイヤ受傷部封止材および／またはタイヤ内圧付与材として使用することができる。
熱膨張した微小球の平均粒子径は、特に限定はされず、用途に応じて自由に設計することができる。例えば、外殻による発泡剤の内包保持率、熱膨張した微小球の耐久性等を考慮すると、好ましくは１〜１０００μｍ、さらに好ましくは５〜８００μｍ、特に好ましくは１０〜５００μｍである。
熱膨張した微小球中に含まれる真比重０．７９ｇ／ｃｃ以上の微小球の含有率（２５℃）は、真比重の均一性を考慮し、内包物質を高い効率で回収し、形状の良好な新規な微小球を得るためには、５重量％以下であることが好ましく、より好ましくは３重量％以下、さらに好ましくは２重量％以下、特に好ましくは１重量％以下である。０．７９ｇ／ｃｃ以上の微小球の含有率は、イソプロピルアルコール（２５℃における比重：０．７９）を用いた比重差分離後の沈降成分の定量により測定される。また、本発明において真比重の測定は、たとえば、試料０．５〜２．０ｇについて、温度２５℃においてイソプロピルアルコールを用いた液置換法（アルキメデス法）により行う。なお、ここでいう真比重は、熱膨張した微小球の１個について真比重を測定した値ではなく、熱膨張した微小球の集合体について真比重を測定した値であり、平均真比重を意味する。
熱膨張した微小球の外殻の厚みについても、特に限定はないが、内包物質を高い効率で回収し、形状の良好な新規な微小球を得るためには、好ましくは０．１〜２０μｍ、より好ましくは０．２〜１０μｍ、さらに好ましくは０．２〜５μｍ、特に好ましくは０．２〜１μｍである。外殻の厚みは、熱膨張した微小球の平均粒子径、発泡剤の内包率、前記液置換法（アルキメデス法）によって測定された真比重から算出される。その算出方法は、以下に示すとおりである。
（１）まず、平均粒子径を有する熱膨張した微小球１粒について考え、その総体積を平均粒子径から算出し、その総重量を真比重から算出し、得られた総重量と発泡剤の内包率から発泡剤ガス重量を算出する。
（２）次いで、総重量と発泡剤ガス重量との差を外殻の重量とし、この外殻の重量と外殻の比重から外殻の体積を算出する。
（３）さらに、総体積と外殻の体積との差を外殻内部の体積とし、この外殻内部の体積から外殻内部の半径を算出する。
（４）最後に、平均粒子径を２で割って平均粒子半径を算出し、この平均粒子半径と外殻内部の半径との差を算出し、外殻の厚みが計算される。
熱膨張した微小球は、再膨張開始温度を有していなくてもよいし、有していてもよい。特に、熱膨張した微小球が再膨張開始温度を有しない場合や、再膨張開始温度を有していても、熱膨張した微小球の再膨張倍率が１００〜５００％の範囲にある場合は、外殻を構成する熱可塑性樹脂の厚みが薄くて、内包物質が外殻を透過しやすくなり、内包物質を高効率で回収できる。
本発明で用いる微小球は、以上説明した熱膨張性微小球や熱膨張した微小球をそのまま使用しても良いが、資源の回収、再利用の観点からは、熱膨張性微小球や熱膨張した微小球をある用途に使用した使用済の微小球が好ましい。
上記用途としては、熱膨張性微小球や熱膨張した微小球が有する種々の特性を利用した用途であれば特に限定はない。上記特性としては、たとえば、意匠性、多孔性、嵩高性、スリッップ防止性、収縮防止性（寸法安定性）、軽量化（コストダウン）、断熱性（保温性、保冷性）、衝撃吸収性（反発弾性）、防音性、制振性、剛性、表面改質性（艶消し、ソフト感付与）、隠蔽性、易剥離性、目止性等を挙げることができる。具体的な用途としては、ランフラットタイヤの主要部材（タイヤとリムとの組立体内部に熱膨張した微小球を充填することにより、タイヤが受傷して、タイヤ内圧が低下した際に、タイヤ受傷部封止材および／またはタイヤ内圧付与材として使用）、ゴムや樹脂の内部添加剤（ゴムや樹脂に添加し、たとえば、加熱成形時に発泡させ、得られる部材の軽量化剤として使用）等を挙げることができる。
次に、以上で説明した微小球中の内包物質を回収する方法を詳しく説明する。
［内包物質の回収方法］
本発明の内包物質の回収方法は、上記で説明した微小球と溶媒とを接触させる接触工程を含む方法である。
この接触工程で使用する溶媒としては、液体であれば特に限定はないが、通常、溶媒の極性の程度、微小球の外殻を構成する熱可塑性樹脂の種類、後述する分離工程における操作性等を考慮して選定される。
溶媒としては、たとえば、水；メタノール、エタノール、プロパノール、エチレングリコール、グリセリン等のアルコール類；プロピルエーテル、ブチルエーテル、ペンチルエーテル、ヘキシルエーテル等のエーテル類；ギ酸メチル、ギ酸エチル、ギ酸プロピル、ギ酸ブチル、酢酸メチル、酢酸エチル、酢酸プロピル、酢酸ブチル、プロピオン酸メチル、プロピオン酸エチル、プロピオン酸プロピル、プロピオン酸ブチル等のエステル類；アセトン、メチルエチルケトン、シクロヘキサノン、ピナコリン、メシチルオキシド等のケトン類；ヘキサン、ヘプタン、オクタン、ノナン、デカン、ウンデカン、ドデカン、シクロヘキサン、メチルシクロヘキサン等の脂肪族炭化水素；ベンゼン、トルエン、キシレン、エチルベンゼン、フェニルアセチレン等の芳香族炭化水素；アセトニトリル、プロピオニトリル等のニトリル類；ジメチルホルムアミド（ＤＭＦ）等のアミド類；ジメチルスルホキサイド（ＤＭＳＯ）等のスルホキサイド類等を挙げることができる。これらの溶媒は、１種または２種以上を併用してもよい。
本発明の回収方法においては、極性溶媒を用いると、内包物質を高効率で回収できるため好ましい。極性溶媒としては、たとえば、水、アルコール類、エーテル類、エステル類、ケトン類、ニトリル類、アミド類、スルホキサイド類等を挙げることができる。これらの極性溶媒の内でも、水、アルコール類が好ましく、また、本発明の回収方法で得られる新規な微小球が良好な形状を保持し、内包物質の単離が容易であるという観点からは、水がさらに好ましい。
極性溶媒はさらに酸性やアルカリ性を示す溶媒であってもよいが、微小球の外殻を構成する熱可塑性樹脂が、カルボキシル基含有単量体等の酸性単量体を含む単量体混合物を重合して得られる場合は、極性溶媒がアルカリ性を示すと好ましく、極性溶媒がアルカリ性を示す水および／またはアルコール類（特にエタノール等）であるとさらに好ましく、本発明の回収方法で得られる新規な微小球が良好な形状を保持し、内包物質の単離が容易であるという観点からは、アルカリ性を示す水が特に好ましい。極性溶媒がアルカリ性を示す場合、極性溶媒のｐＨについては、特に限定はないが、９〜１４が好ましく、１１〜１３がさらに好ましい。
接触工程においては、微小球と溶媒とを混合して接触させる。微小球と溶媒との混合比率については、特に限定はないが、回収効率の向上や、経済性等を考慮すると、溶媒１Ｌ当たりの微小球が０．１〜３０００ｇであると好ましく、１０〜２０００ｇであるとさらに好ましく、１００〜１０００ｇであると特に好ましい。
接触工程における微小球と溶媒との接触時間は、溶媒、内包物質、微小球の外殻を構成する熱可塑性樹脂や、作業性等を考慮して適宜設定され、特に限定はないが、たとえば０．１〜１０００時間である。
接触工程における微小球と溶媒との接触温度は、接触時間と同様に適宜設定され、特に限定はない。しかし、余りにも低い温度で両者を接触させることは操作上有利ではないことや、内包物質の沸点が通常室温あるいはそれよりもやや高い温度である場合が多いことを考慮すると、接触温度は、たとえば−５０〜１００℃である。また、接触温度は内包物質の沸点以下が好ましい。
接触工程における接触時間および接触温度は、微小球の外殻の厚みを考慮して適宜設定してもよい。
微小球の外殻の厚みが２μｍ以上の場合（たとえば、微小球が熱膨張性微小球の場合）、内包物質の回収効率の向上を考慮すると、接触工程における接触時間は、１〜１０００時間であると好ましく、１０〜１０００時間であるとさらに好ましく、１００〜１０００時間であると特に好ましい。接触工程における接触温度は、３０〜１００℃であると好ましく、５０〜１００℃であるとさらに好ましく、７０〜１００℃であると特に好ましい。この場合に使用する溶媒としては、微小球と溶媒との接触温度以上の沸点を持つものが望ましく、上記で例示した溶媒のうちでも、沸点５０℃以上の溶媒を挙げることができる。
次に、微小球の外殻の厚みが２μｍ未満の場合（たとえば、微小球が熱膨張した微小球の場合）、内包物質の回収効率の向上を考慮すると、接触工程における接触時間は、０．１〜５００時間であると好ましく、０．１〜１００時間であるとさらに好ましい。接触工程における接触温度は、０〜８０℃であると好ましい。この場合に使用する溶媒としては、微小球と溶媒との接触温度以上の沸点を持つものが望ましく、上記で例示した溶媒のうちでも、沸点２０℃以上の溶媒を挙げることができる。
本発明の内包物質の回収方法においては、微小球と溶媒とを接触させることによって、微小球に内包された内包物質を回収することができる。その作用については、確証はないが、外殻を構成する熱可塑性樹脂が溶媒によって膨潤や変質し、内包された内包物質が濃度勾配にしたがって溶媒中に透過、拡散するものと推測される。
本発明の内包物質の回収方法は、分離工程をさらに含むと好ましい。分離工程は、前記接触工程で得られた微小球および溶媒を含む混合物から前記内包物質を回収する工程である。
分離工程は、接触工程とともに行ってもよく、接触工程後に行ってもよいが、分離工程を接触工程とともに行うことによって、内包物質を短時間で分離回収することができる。
分離工程を行う具体的な手段については、特に限定はなく、たとえば、内包物質の蒸留分離、抽出分離、遠心分離、吸着分離等を挙げることができる。
蒸留分離は、内包物質と溶媒との沸点差を利用して内包物質を分離回収する方法である。沸点差は、作業効率を上げるために沸点差を大きくする方が好ましい。沸点差は、たとえば、５℃以上が好ましく、１０℃以上がさらに好ましく、２０℃以上が特に好ましい。蒸留分離においては、内包物質を一旦蒸気化させ冷却装置で液化して分離するが、内包物質の沸点が通常室温あるいはそれよりもやや高い温度である場合が多いことを考慮して、冷却装置や液化した内包物質の貯蔵器等に用いる冷媒の温度を低めに制御することが好ましい。冷媒の温度と内包物質の沸点との温度差は、たとえば、３０℃以上が好ましく、５０℃以上がさらに好ましく、１００℃以上が特に好ましい。
抽出分離および遠心分離は、いずれも内包物質と溶媒とが相分離する性質を利用して分離回収する方法である。抽出分離や遠心分離を行う場合、溶媒としては、内包物質と混合した場合に相分離する性質を有するものが好ましい。溶媒としては、たとえば、水；メタノール、エタノール等のアルコール類等を挙げることができる。抽出分離で容易に相分離しない場合、遠心分離を行って内包物質と溶媒とを相分離させてもよい。抽出分離や遠心分離によって相分離させた内包物質は、デカンテーション等の分液操作を経て、分離回収される。
吸着分離は、気化した物質を活性炭などの吸着剤を用いた吸着ユニットにより捕捉して回収する方法である。吸着ユニットに捕捉された物質は蒸気により脱着されて再生され、深冷凝縮によって液化回収される。
上記接触工程および分離工程において、微小球および溶媒を含む混合物を攪拌してもよいし、攪拌しなくてもよいが、攪拌した場合は、微小球および溶媒の接触効率が高まると考えられる。前記攪拌に用いる攪拌機については、特に限定はなく、たとえば、ホモミキサーやラインミキサー等の一般的な攪拌機を挙げることができる。攪拌速度についても特に限定はない。
上記接触工程および分離工程を行うにあたり、その圧力雰囲気についても特に限定はなく、減圧下、常圧下、加圧下のいずれの圧力下で行ってもよい。
次に、接触工程後に得ることができる新規な微小球について説明する。
［新規な微小球］
本発明の新規な微小球（以下、微小球ａということがある。）は、上記回収方法における接触工程後に得ることができ、熱可塑性樹脂を外殻としている微小球である。
微小球ａは、その外殻に内包物質に代わって溶媒が内包されており、新規な微小球である。微小球ａでは少なくとも溶媒が内包されているが、回収されずに残った内包物質が溶媒とともに内包されていてもよい。
接触工程後の混合物から溶媒を除去して乾燥した微小球ａを単離してもよいが、凝集や融着が生じない点を考慮すると、微小球ａを液体で湿潤された状態で取扱う方が好ましい。
上記液体としては、上記回収方法で説明した溶媒をそのまま用いることができるが、微小球ａの用途に応じて、ジブチルフタレート、ジイソオクチルフタレート、ジオクチルアジベート、トリクレジルホスフェート、トリエチルシトレート、アセチルトリブチルシトレート、オクチルアルコール等の可塑剤（プラスチック、エラストマー、シーラント、塗料等に用いる場合）；ジシクロペンタジエンやスチレン等の単量体（軽量発泡成形体や接着剤用に用いる場合）；非イオン界面活性剤、アルキレングリコール、ポリアルキレングリコール、グリセリン、シリコーンオイル、流動パラフィン、油脂類等を、液体として用いてもよい。接触工程後の混合物中の溶媒を、液体に置換することによって微小球ａを液体で湿潤された状態にすることができる。
微小球ａの平均粒子径については、特に限定はないが、微小球ａが湿潤された状態の場合、好ましくは１〜１０００μｍ、さらに好ましくは５〜８００μｍ、特に好ましくは１０〜５００μｍ、最も好ましくは１〜１５０μｍである。
微小球ａの真比重については、特に限定はないが、微小球ａが乾燥された状態の場合、好ましくは０．００１〜１．５ｇ／ｃｃ、さらに好ましくは０．００１〜１．０ｇ／ｃｃ、特に好ましくは０．００１〜０．８ｇ／ｃｃである。
微小球ａの用途については、前述の熱膨張性微小球や熱膨張した微小球が有する種々の特性を利用した用途や、微小球ａが微小な粒子状であることを利用した用途であれば特に限定はない。微小球ａを、樹脂等の有機材料、無機材料等の充填材として利用してもよく、例えば、押出しセメント成形品やシーリング剤のフィラー、樹脂粘土のフィラー、窯業サイディングの補強フィラー、木質繊維板の補強フィラー、手洗い石鹸や業務用洗剤の研磨剤、ブロッキング防止剤、平滑性付与剤、軽量骨材の代替物、多孔化付与剤、流動化剤、粉塵防止剤、緑化促進剤、法面侵食防止剤等が挙げられる。First, a microsphere encapsulating an inclusion substance used in the present invention will be described.
[Microsphere]
The microspheres used in the present invention are microspheres composed of an outer shell made of a thermoplastic resin and an inclusion substance contained therein and having a boiling point equal to or lower than the softening point of the thermoplastic resin.
The encapsulation rate of the encapsulated substance contained in the microsphere is not particularly limited, but is preferably 5% or more, more preferably 15% or more, particularly preferably from the viewpoint of improving the working efficiency when recovering the encapsulated substance. Is 30% or more.
The encapsulation rate of the encapsulated substance (hereinafter, also referred to as the encapsulating rate of the foaming agent) is a value representing the ratio of the weight of the encapsulated substance encapsulated in the microsphere to the weight of the microsphere in percentage.
The microspheres used in the present invention are roughly classified into thermally expandable microspheres and thermally expanded microspheres (obtained by thermally expanding the thermally expandable microspheres). These are described in detail below.
a. Thermally expandable microsphere
The heat-expandable microspheres are composed of an outer shell made of a thermoplastic resin and an inclusion substance contained therein and having a boiling point not higher than the softening point of the thermoplastic resin, and the inclusion substance acts as a foaming agent. The thermally expandable microsphere exhibits thermal expandability (the property that the entire microsphere expands by heating) as the entire microsphere. In the following description, the inclusion substance and the foaming agent are used synonymously.
The foaming agent is not particularly limited as long as it has a boiling point equal to or lower than the softening point of the thermoplastic resin. For example, hydrocarbons having 1 to 12 carbon atoms and their halides; fluorine-containing compounds; tetraalkylsilanes; Examples thereof include a compound that thermally decomposes by heating amide or the like to generate a gas. These foaming agents may be used alone or in combination of two or more.
Examples of the hydrocarbon having 1 to 12 carbon atoms include propane, cyclopropane, propylene, butane, normal butane, isobutane, cyclobutane, normal pentane, cyclopentane, isopentane, neopentane, normal hexane, isohexane, cyclohexane, heptane, and cycloheptane. , Hydrocarbons such as octane, isooctane, cyclooctane, 2-methylpentane, 2,2-dimethylbutane, and petroleum ether. These hydrocarbons may be linear, branched or alicyclic, and are preferably aliphatic.
Examples of the hydrocarbon halide having 1 to 12 carbon atoms include methyl chloride, methylene chloride, chloroform and carbon tetrachloride. These halides are preferably the above-described hydrocarbon halides (fluoride, chloride, bromide, iodide, etc.).
The fluorine-containing compound is not particularly limited, and for example, a compound having an ether structure, not containing a chlorine atom and a bromine atom, and having 2 to 10 carbon atoms is preferable. Specifically, C ₃ H ₂ F ₇ OCF ₂ H, C ₃ HF ₆ OCH ₃ , C ₂ HF ₄ OC ₂ H ₂ F ₃ , C ₂ H ₂ F ₃ OC ₂ H ₂ F ₃ , C ₄ HF ₈ OCH ₃ , C ₃ H ₂ F ₅ OC ₂ H ₃ F ₂ , C ₃ HF ₆ OC ₂ H ₂ F ₃ , C ₃ H ₃ F ₄ OCHF ₂ , C ₃ HF ₆ OC ₃ H ₂ F ₅ , C ₄ H ₃ F ₆ OCHF ₂ , C ₃ H ₃ F ₄ OC ₂ HF ₄ , C ₃ HF ₆ OC ₃ H ₃ F ₄ , C ₃ F ₇ OCH ₃ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , C ₇ F ₁₅ OC ₂ H ₅ And the like. The (fluoro) alkyl group of the hydrofluoroether may be linear or branched.
For example, the foaming agent may be entirely composed of a fluorine-containing compound, but a substance other than the fluorine-containing compound having a boiling point below the softening point of the thermoplastic resin may be used in combination with the fluorine-containing compound. . Such a substance is not particularly limited, and can be selected from, for example, those exemplified as the foaming agent described above. Substances other than the fluorine-containing compound can be appropriately selected according to the thermal expansion temperature range of the thermally expandable microspheres.
In the foaming agent, the weight ratio of the fluorine-containing compound is preferably more than 50% by weight of the whole foaming agent, more preferably more than 80% by weight, and particularly preferably more than 95% by weight. The higher the weight ratio of the fluorine-containing compound in the foaming agent, the more the physical properties of the fluorine-containing compound are reflected in the thermally expandable microspheres, and it is possible to impart physical properties such as flame retardancy and incombustibility to the thermally expandable microspheres. it can.
The heat-expandable microsphere is composed of, for example, a thermoplastic resin obtained by polymerizing a monomer mixture containing a radical polymerizable monomer, and by adding a polymerization initiator appropriately to the monomer mixture, An outer shell of expandable microspheres can be formed.
The radical polymerizable monomer is not particularly limited. For example, nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile; acrylic acid, methacrylic acid, itaconic acid Carboxyl group-containing monomers such as maleic acid, fumaric acid and citraconic acid; vinylidene chloride; vinyl acetate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylate monomers such as t-butyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, β-carboxyethyl acrylate; styrene, α-methylstyrene Styrene monomers such as chlorostyrene, acrylamide; acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide; N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N-cyclohexylmaleimide, Mention may be made of maleimide monomers such as N-laurylmaleimide. As for the carboxyl group-containing monomer, some or all of the carboxyl groups may be neutralized during polymerization.
These radically polymerizable monomers may be used alone or in combination of two or more. Among these, the monomer mixture was selected from a nitrile monomer, a (meth) acrylic acid ester monomer, a carboxyl group-containing monomer, a styrene monomer, vinyl acetate, and vinylidene chloride. A monomer mixture containing at least one radically polymerizable monomer is preferred. In particular, the monomer mixture is preferably a monomer mixture containing a nitrile monomer as an essential component because heat resistance can be imparted. The weight ratio of the nitrile monomer is preferably 80% by weight or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more, considering heat resistance with respect to the monomer mixture. It is.
In addition, when the monomer mixture is a monomer mixture containing a nitrile monomer and a carboxyl group-containing monomer as an essential component, heat resistance can be imparted, and the thermally expandable microspheres can be expanded. The resulting thermally expanded microspheres can be manufactured to have a re-expandable capacity, and re-expansion is initiated at a temperature of 90 ° C. or higher (preferably 100 ° C. or higher, more preferably 120 ° C. or higher). Therefore, it is more preferable. The weight ratio of the nitrile monomer is determined by taking into account the retention rate and foamability of the encapsulated foaming agent, adjusting the re-expansion start temperature of the thermally expanded microsphere, and evaluating the internal pressure and high-speed running performance. The amount of the monomer mixture is preferably 20 to 95% by weight, more preferably 20 to 80% by weight, still more preferably 20 to 60% by weight, and particularly preferably 20 to 50% by weight. Yes, most preferably 20-40% by weight. In addition, the weight ratio of the carboxyl group-containing monomer is to adjust the re-expansion start temperature of the thermally expanded microsphere, normal internal pressure high-speed running performance evaluation, and further, the inclusion retention rate and foamability of the encapsulated foaming agent, etc. Is preferably from 5 to 80% by weight, more preferably from 20 to 80% by weight, still more preferably from 40 to 80% by weight, particularly preferably from 50 to 80%, based on the monomer mixture. % By weight, most preferably 60-80% by weight.
When the monomer mixture contains a carboxyl group-containing monomer as an essential component, it reacts with the carboxyl group of the carboxyl group-containing monomer as a monomer other than the carboxyl group-containing monomer contained in the monomer component A monomer may be contained. Examples of the monomer that reacts with the carboxyl group of the carboxyl group-containing monomer include, for example, N-methylol (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth). Acrylate, magnesium mono (meth) acrylate, zinc mono (meth) acrylate, vinyl glycidyl ether, propenyl glycidyl ether, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Examples thereof include butyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate. The weight ratio of the monomer that reacts with the carboxyl group of the carboxyl group-containing monomer is preferably 0.1 to 10% by weight, more preferably 1 to 8% by weight, based on the monomer mixture. Most preferably, it is 3 to 5% by weight.
The monomer mixture may contain a polymerizable monomer (crosslinking agent) having two or more polymerizable double bonds in addition to the radical polymerizable monomer. By polymerizing using a crosslinking agent, the content of aggregated microspheres contained in the thermally expanded microspheres obtained by this production method is reduced, and the retention rate of the encapsulated foaming agent after thermal expansion (encapsulation retention) Rate) is suppressed, and effective thermal expansion can be achieved.
In the present invention, the encapsulated retention rate (%) of the foaming agent after thermal expansion is the encapsulating rate of the foaming agent encapsulated in the thermally expandable microsphere before expansion. ₁ And the encapsulating rate of the foaming agent encapsulated in the thermally expanded microspheres obtained by thermal expansion is G ₂ Then G ₂ / G ₁ It is defined by x100.
The crosslinking agent is not particularly limited. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) Acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, PEG # 200 Di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol dimethacrylate, 1,6-hexanedi Di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimethylolpropane trimethacrylate, glycerin dimethacrylate, dimethylol-tricyclodecane diacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetraacrylate , Dipentaerythritol hexaacrylate, neopentyl glycol acrylic acid benzoate, trimethylolpropane acrylic acid benzoate, 2-hydroxy-3-acryloyloxypropyl methacrylate, hydroxypivalate neopentyl glycol diacrylate, ditrimethylol Di (meth) acrylates such as propanetetraacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate Mention may be made of the door compound. These crosslinking agents may be used alone or in combination of two or more.
The weight ratio of the crosslinking agent is not particularly limited, but it is preferable for the monomer mixture in consideration of the degree of crosslinking, the retention rate of the foaming agent encapsulated in the outer shell, heat resistance and thermal expansion. Is 0.01 to 5% by weight, more preferably 0.05 to 3% by weight.
There is no limitation in particular about a polymerization initiator, A well-known polymerization initiator can be used. For example, t-butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2 -Ethylhexanoylperoxy) hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylper Oxyneodecanoate, t-hexylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, kumi Luperoxyneodecanoate, di-n-propylperoxydicarbonate, diisopropylperoxydica Bonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-3 -Peroxides such as methoxybutyl peroxide 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearyl peroxide, succinic acid peroxide, benzoyl peroxide; 2,2 '-Azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'- Azobis (2-methylpropionate ), And 2,2'-azobis (2-methylbutyronitrile) azo compounds such like. The polymerization initiator is preferably an oil-soluble polymerization initiator that is soluble in the radical polymerizable monomer.
Thermally expansible microspheres can be manufactured using various methods used in a conventionally known method for manufacturing thermally expandable microcapsules.
That is, a monomer mixture containing a radically polymerizable monomer and optionally containing a crosslinking agent, a polymerization initiator, and a foaming agent are mixed, and the resulting mixture is mixed with an aqueous suspension containing an appropriate dispersion stabilizer and the like. For example, suspension polymerization in a suspension.
Colloidal silica, colloidal calcium carbonate, magnesium hydroxide, calcium phosphate, aluminum hydroxide, ferric hydroxide, calcium sulfate, sodium sulfate, calcium oxalate, calcium carbonate, barium carbonate, magnesium carbonate, alumina sol Etc. The dispersion stabilizer is preferably used in a proportion of 0.1 to 20% by weight based on the monomer mixture. Other dispersion stability aids include condensation products of diethanolamine and aliphatic dicarboxylic acids, polymer type dispersion stability aids such as gelatin, polyvinylpyrrolidone, methylcellulose, polyethylene oxide, polyvinyl alcohol, alkyltrimethylammonium chloride, dialkyldimethylchloride. Various emulsifiers such as a cationic surfactant such as ammonium, an anionic surfactant such as sodium alkylsulfate, and an amphoteric surfactant such as alkyldimethylaminoacetic acid betaine and alkyldihydroxyethylaminoacetic acid betaine may be used. The dispersion stabilizing aid is preferably used in a proportion of 0.05 to 2% by weight based on the monomer mixture.
The aqueous suspension containing the dispersion stabilizer is prepared by blending a dispersion stabilizer, a dispersion stabilization auxiliary agent, and the like with water (for example, ion exchange water). The pH of the aqueous suspension at the time of polymerization is appropriately determined depending on the type of the dispersion stabilizer and dispersion stabilizing aid used. Further, a water-soluble reducing agent may be added to the aqueous suspension, and the formation of aggregated microspheres during polymerization is suppressed. Examples of water-soluble reducing agents include alkali metal nitrites such as sodium nitrite and potassium nitrite, stannous chloride, stannic chloride, ferrous chloride, ferric chloride, ferrous sulfate, and water-soluble ascorbine. Examples include acids. Among these, alkali metal nitrite is preferable from the viewpoint of stability in water. The addition amount is preferably 0.0001 to 1% by weight, more preferably 0.0003 to 0.1% by weight, based on the monomer mixture.
Although superposition | polymerization temperature is freely set by the kind of polymerization initiator, Preferably it is 40-100 degreeC, More preferably, it is 45-90 degreeC, Most preferably, it controls in the range of 50-85 degreeC. The initial polymerization pressure is 0 to 5.0 MPa, more preferably 0.1 to 3.0 MPa, and particularly preferably 0.2 to 2.0 MPa in terms of gauge pressure.
The resulting thermally expandable microspheres have good foaming performance, can be used to fill tire and rim assemblies, and can be used as a tire internal pressure imparting material. From the viewpoint that the thickness of the thermoplastic resin which is the outer shell of the sphere can ensure the encapsulating retention rate of the encapsulated foaming agent, the foaming agent is 2 to 85% by weight of the entire thermally expandable microsphere, preferably 5%. It is adjusted to be ˜60 wt%, more preferably 7 to 50 wt%. In particular, when the foaming agent contains a fluorine-containing compound, it is preferably 10 to 60% by weight, more preferably 15 to 50% by weight.
The average particle diameter of the heat-expandable microsphere is not particularly limited because it can be designed freely according to the use, and is preferably 1 to 100 μm, more preferably 2 to 80 μm, and particularly preferably 5 to 60 μm. is there.
Further, the coefficient of variation CV of the particle size distribution of the thermally expandable microsphere is not particularly limited, but is preferably 30% or less, more preferably 27% or less, and particularly preferably 25% or less. The variation coefficient CV is calculated by the following calculation formulas (1) and (2).

(In the formula, s is the standard deviation of the particle diameter, <x> is the average particle diameter, x _i Is the i-th particle diameter, and n is the number of particles. )
The thermally expandable microspheres may be added or modified by components other than the outer shell and the inclusion substance. For example, in the thermally expandable microsphere, it is preferable to use a fine particle filler adhered to the outer surface of the outer shell from the viewpoint of improving dispersibility and improving fluidity during use.
The fine particle filler may be either an organic or inorganic filler, and the type and amount thereof are appropriately selected according to the purpose of use.
Examples of organic fillers include metal soaps such as magnesium stearate, calcium stearate, zinc stearate, barium stearate, lithium stearate; polyethylene wax, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid Synthetic waxes such as amide and hardened castor oil; resin powders such as polyacrylamide, polyimide, nylon, polymethyl methacrylate, polyethylene, and polytetrafluoroethylene.
Inorganic fillers having a layered structure such as talc, mica, bentonite, sericite, carbon black, molybdenum disulfide, tungsten disulfide, graphite fluoride, calcium fluoride, boron nitride, etc .; , Alumina, mica, calcium carbonate, calcium hydroxide, calcium phosphate, magnesium hydroxide, magnesium phosphate, barium sulfate, titanium dioxide, zinc oxide, ceramic beads, glass beads, crystal beads and the like.
These fine particle fillers may be used alone or in combination of two or more.
Among the above, the fine particle filler adhering to the outer surface of the outer shell has a melting point of 90 ° C. or higher (preferably 100 ° C. or higher, more preferably 110 ° C. or higher, more preferably 120 ° C. or higher, particularly preferably 150 ° C. or higher, most Preferably an organic compound having a melting point of 200 ° C. or higher, or an inorganic compound having a layered structure (preferably at least one selected from carbon black, molybdenum disulfide, tungsten disulfide, fluorinated graphite and boron nitride), It is preferable that it is a heat fusion inhibitor. Here, the thermal fusion inhibitor prevents thermal fusion of the thermally expandable microspheres and / or the outer shell resin of the thermally expanded microspheres, and further, the thermally expandable microspheres and / Alternatively, heat fusion with thermally expanded microspheres is prevented and the foaming performance is not impaired. As a result, for example, when thermally expanded microspheres obtained by expanding thermally expandable microspheres and filled with thermally expanded microspheres having a re-expandable capacity are filled inside the tire and rim assembly, the tire is damaged and tire internal pressure is reduced. Even if the damage decreases, the tire damage part can be quickly sealed and a high tire internal pressure imparting function can be exhibited. As a result, even a damaged tire can travel a necessary distance. This effect is particularly remarkable when the foaming agent contains a fluorine-containing compound.
In the case of thermally expandable microspheres using a thermoplastic resin as an outer shell obtained by polymerizing a monomer mixture containing a nitrile monomer and a carboxyl group-containing monomer as essential components, 90 ° C. or more for thermally expanded microspheres that have a sufficient capacity to re-expand and are obtained by expanding thermally expandable microspheres. Re-expansion can be started at a temperature (preferably 100 ° C. or higher, more preferably 120 ° C. or higher), and the above effect becomes remarkable.
The average particle diameter of the fine particle filler is preferably 1/10 or less of the average particle diameter of the heat-expandable microspheres before adhesion. Here, the average particle size means the average particle size of primary particles.
The amount of the fine particle filler adhering to the thermally expandable microsphere is not particularly limited, but the function of the fine particle filler can be sufficiently exerted, and considering the size of the true specific gravity of the thermally expandable microsphere, etc. It is preferably 0.1 to 95% by weight, more preferably 0.5 to 60% by weight, particularly preferably 5 to 50% by weight, and most preferably 8 to 30% by weight, based on the thermally expandable microspheres.
Adhesion of the particulate filler to the outer surface of the thermally expandable microsphere can be performed by mixing the thermally expandable microsphere and the particulate filler. The mixing is not particularly limited, and can be performed using an apparatus having a very simple mechanism such as a container and a stirring spring. Moreover, you may use the powder mixer which can perform a general rocking | swiveling or stirring. Examples of the powder mixer include a powder mixer that can perform rocking stirring or stirring, such as a ribbon mixer and a vertical screw mixer. In recent years, super mixers (manufactured by Kawata Co., Ltd.), high-speed mixers (manufactured by Fukae Co., Ltd.), and Newgram Machines (Seishin Enterprise Co., Ltd.), which are efficient and multifunctional powder mixers by combining stirring devices May be used.
The thermally expandable microspheres, for example, are filled in the tire and rim assembly as they are and expanded by heating at a temperature equal to or higher than the expansion start temperature of the thermally expandable microspheres, and used as a volume retaining material. can do. Moreover, you may use as it is for the use of the weight reducing filler of paints, such as a motor vehicle, the foaming particle for foaming ink for wallpaper and clothes decoration, and the foaming material for the resin composition weight reduction as it is.
Next, the thermally expanded microsphere will be described.
b. Thermally expanded microspheres
The thermally expanded microsphere is obtained by thermally expanding the thermally expandable microsphere described above. The method for producing thermally expanded microspheres is not particularly limited as long as the method includes a step of heating and thermally expanding thermally expandable microspheres, and conventionally known methods can be applied. However, the following two methods can be mentioned as preferable methods.
(A) A step of causing a gas fluid containing the thermally expandable microspheres (raw materials) described above to flow through a gas introduction pipe provided with a dispersion nozzle at the outlet and installed inside the hot air flow, and jetting from the dispersion nozzle ( Injection step), a step of causing the gaseous fluid to collide with a collision plate installed in a downstream portion of the dispersion nozzle, and dispersing thermally expandable microspheres in the hot air stream (dispersion step), and a dispersed thermal expansion property. And a step (expansion step) of expanding the microsphere by heating the microsphere to a temperature higher than the expansion start temperature in the hot air stream.
(B) A gas fluid containing the thermally expandable microspheres (raw materials) described above is flown into at least one gas introduction pipe provided with a dispersion nozzle at the outlet and installed outside the hot air flow, and injected from the dispersion nozzle A step of dispersing the thermally expandable microspheres in the hot air flow (dispersion step), and a step of expanding the dispersed thermally expandable microspheres by heating to or above the expansion start temperature in the hot air flow (expansion step) A manufacturing method comprising:
In the above manufacturing method, energy efficiency is high, temperature control is easy, almost the same thermal history can be continuously given to any thermally expandable microspheres that are raw materials, and dispersibility in airflow Is expensive. For this reason, the change in the coefficient of variation of the particle size distribution before and after expansion is small, and the quality (particularly, the particle size distribution and true specific gravity distribution) of the obtained thermally expanded microspheres is high. That is, the generation of aggregated microspheres contained in the obtained thermally expanded microspheres can be suppressed as much as possible, and the content of raw materials and slightly expanded microspheres can be extremely reduced.
Further, in the above manufacturing method, by controlling the expansion condition, the obtained thermally expanded microsphere may or may not have a reexpansion start temperature. Note that the microsphere has a re-expansion start temperature means that the thermally expanded microsphere once manufactured still has a property of thermal expansion, and when the thermally expanded microsphere is heated, the phenomenon of heating and expanding again occurs. It means being seen. And the temperature which starts the heating expansion is called re-expansion start temperature. Further, the fact that the thermally expanded microsphere has a reexpansion start temperature is synonymous with the fact that the expansion ratio at the maximum (re) expansion temperature is more than 100%. On the other hand, the fact that the microsphere does not have a re-expansion start temperature means that the microsphere has almost completely thermally expanded.
There is no particular limitation on the control of the expansion conditions. For example, first, parameters such as a raw material supply amount, a hot air flow rate, and a raw material dispersed gas amount are fixed, and the temperature of the hot air flow (hereinafter sometimes referred to as “hot air temperature”) is changed. Next, while changing the hot air temperature stepwise and fixing other parameters constant, the raw microspheres were expanded at each temperature, the true specific gravity of the obtained microspheres was measured, and the hot air temperature (x-axis) ) And true specific gravity (y-axis) are plotted. In this graph, by setting the temperature region corresponding to the lowest true specific gravity (minimum value in the graph) to the hot air temperature, the obtained thermally expanded microspheres can be manufactured so as not to have a reexpansion start temperature.
When producing expanded microspheres having a desired true specific gravity, the hot air temperature corresponding to the desired true specific gravity is set in the graph. As a result, the expansion conditions are controlled, and it is possible to manufacture thermally expanded microspheres having a desired reexpansion capacity.
Furthermore, when changing the raw material supply amount and / or the raw material dispersed gas amount, the hot air temperature and the like are changed in consideration of the amount of heat supplied by the hot air flow and the total heat capacity of the thermally expandable microsphere as the raw material, Control inflation conditions. For example, when increasing the raw material supply amount and the raw material dispersion gas amount, the hot air temperature is raised. When reducing the raw material supply amount and the raw material dispersion gas amount, the hot air temperature is lowered.
In the above manufacturing method, energy efficiency is high, temperature control is easy, almost the same thermal history can be continuously given to any thermally expandable microspheres that are raw materials, and dispersibility in airflow Is expensive. For this reason, the change in the coefficient of variation of the particle size distribution before and after expansion is small, and the quality (particularly, the particle size distribution and true specific gravity distribution) of the obtained thermally expanded microspheres is high. That is, the generation of aggregated microspheres contained in the obtained thermally expanded microspheres can be suppressed as much as possible, and the content of raw materials and slightly expanded microspheres can be extremely reduced.
The thermally expanded microspheres thus obtained can be used as a main member of a run flat tire, for example. That is, when the tire and the rim are filled with thermally expanded microspheres, when the tire is damaged and the internal pressure of the tire decreases, the tire damaged portion sealing material and / or the tire internal pressure imparting material is used. Can be used.
The average particle diameter of the thermally expanded microsphere is not particularly limited and can be freely designed according to the application. For example, considering the retention rate of the foaming agent by the outer shell, the durability of the thermally expanded microspheres, etc., it is preferably 1 to 1000 μm, more preferably 5 to 800 μm, and particularly preferably 10 to 500 μm.
The content (25 ° C) of microspheres with a true specific gravity of 0.79 g / cc or more contained in the thermally expanded microspheres is high in efficiency by recovering the encapsulated material with high efficiency in consideration of the uniformity of the true specific gravity. In order to obtain such novel microspheres, the content is preferably 5% by weight or less, more preferably 3% by weight or less, still more preferably 2% by weight or less, and particularly preferably 1% by weight or less. The content of microspheres of 0.79 g / cc or more is measured by quantifying the sediment component after separation with a specific gravity difference using isopropyl alcohol (specific gravity at 25 ° C .: 0.79). In the present invention, the true specific gravity is measured by, for example, a liquid replacement method (Archimedes method) using isopropyl alcohol at a temperature of 25 ° C. for 0.5 to 2.0 g of the sample. Here, the true specific gravity is not a value obtained by measuring the true specific gravity of one of the thermally expanded microspheres, but a value obtained by measuring the true specific gravity of an aggregate of thermally expanded microspheres, and means an average true specific gravity. To do.
The thickness of the outer shell of the thermally expanded microsphere is not particularly limited, but in order to recover the encapsulated material with high efficiency and obtain a new microsphere having a good shape, preferably 0.1 to 20 μm, More preferably, it is 0.2-10 micrometers, More preferably, it is 0.2-5 micrometers, Most preferably, it is 0.2-1 micrometer. The thickness of the outer shell is calculated from the average particle diameter of the thermally expanded microspheres, the encapsulating rate of the foaming agent, and the true specific gravity measured by the liquid replacement method (Archimedes method). The calculation method is as follows.
(1) First, consider one thermally expanded microsphere having an average particle size, calculate the total volume from the average particle size, calculate the total weight from the true specific gravity, and calculate the total weight and the foaming agent The foaming agent gas weight is calculated from the encapsulation rate.
(2) Next, the difference between the total weight and the foaming agent gas weight is defined as the weight of the outer shell, and the volume of the outer shell is calculated from the weight of the outer shell and the specific gravity of the outer shell.
(3) Further, the difference between the total volume and the volume of the outer shell is defined as the volume inside the outer shell, and the radius inside the outer shell is calculated from the volume inside the outer shell.
(4) Finally, the average particle diameter is divided by 2 to calculate the average particle radius, the difference between this average particle radius and the radius inside the outer shell is calculated, and the thickness of the outer shell is calculated.
The thermally expanded microsphere may or may not have a re-expansion start temperature. In particular, when the thermally expanded microsphere does not have a re-expansion start temperature, or even when it has a re-expansion start temperature, the re-expansion magnification of the thermally expanded microsphere is in the range of 100 to 500%, Since the thickness of the thermoplastic resin constituting the outer shell is thin, the inclusion substance can easily permeate the outer shell, and the inclusion substance can be recovered with high efficiency.
As the microspheres used in the present invention, the above-described thermally expandable microspheres or thermally expanded microspheres may be used as they are. However, from the viewpoint of resource recovery and reuse, the thermally expandable microspheres and the thermally expanded microspheres may be used. Used microspheres that are used for certain applications are preferred.
The application is not particularly limited as long as it uses various characteristics of the thermally expandable microsphere and the thermally expanded microsphere. The above properties include, for example, designability, porosity, bulkiness, anti-slip property, anti-shrinkage property (dimensional stability), light weight (cost reduction), heat insulation property (heat retention property, cold insulation property), impact absorption property ( Rebound resilience), sound insulation, vibration damping, rigidity, surface modification (matte, soft feeling imparted), concealability, easy peelability, sealability, and the like. Specifically, the main components of run-flat tires (when tires are damaged by filling the thermally expanded microspheres inside the tire and rim assembly, the tire damage is reduced Used as part sealing material and / or tire internal pressure imparting material), rubber and resin internal additives (added to rubber and resin, for example, foamed at the time of thermoforming, and used as a lightening agent for the resulting member), etc. Can be mentioned.
Next, a method for recovering the encapsulated substance in the microsphere described above will be described in detail.
[Method of collecting encapsulated substances]
The method for recovering an encapsulated substance of the present invention is a method including a contact step of bringing the microspheres described above into contact with a solvent.
The solvent used in this contact step is not particularly limited as long as it is a liquid, but usually the degree of polarity of the solvent, the type of thermoplastic resin constituting the outer shell of the microsphere, the operability in the separation step described later, etc. Is selected.
Examples of the solvent include water; alcohols such as methanol, ethanol, propanol, ethylene glycol, and glycerin; ethers such as propyl ether, butyl ether, pentyl ether, and hexyl ether; methyl formate, ethyl formate, propyl formate, butyl formate, Esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, pinacholine, mesityl oxide; hexane, Aliphatic hydrocarbons such as heptane, octane, nonane, decane, undecane, dodecane, cyclohexane, methylcyclohexane; benzene, toluene, xylene, ethylbenzene, phenylacetate Aromatic hydrocarbons Ren like; acetonitrile, nitriles such as propionitrile, amides such as dimethylformamide (DMF); and dimethyl sulfoxide (DMSO) sulfoxides such like. These solvents may be used alone or in combination of two or more.
In the recovery method of the present invention, it is preferable to use a polar solvent because the encapsulated substance can be recovered with high efficiency. Examples of the polar solvent include water, alcohols, ethers, esters, ketones, nitriles, amides, sulfoxides, and the like. Among these polar solvents, water and alcohols are preferable, and from the viewpoint that the novel microspheres obtained by the recovery method of the present invention maintain a good shape and the inclusion substances can be easily isolated. More preferred is water.
The polar solvent may be a solvent that exhibits acidity or alkalinity, but the thermoplastic resin that forms the outer shell of the microsphere polymerizes a monomer mixture containing an acidic monomer such as a carboxyl group-containing monomer. When the polar solvent is alkaline, the polar solvent is preferably alkaline and the polar solvent is more preferably water and / or alcohols (especially ethanol, etc.). From the viewpoint of maintaining a good shape of the sphere and facilitating the isolation of the inclusion substance, water showing alkalinity is particularly preferable. When a polar solvent shows alkalinity, although there is no limitation in particular about pH of a polar solvent, 9-14 are preferable and 11-13 are more preferable.
In the contacting step, the microspheres and the solvent are mixed and contacted. The mixing ratio of the microspheres and the solvent is not particularly limited, but considering the improvement in recovery efficiency, economy, etc., the microspheres per liter of the solvent is preferably 0.1 to 3000 g, and 10 to 2000 g. Is more preferable, and 100 to 1000 g is particularly preferable.
The contact time between the microsphere and the solvent in the contacting step is appropriately set in consideration of the solvent, the inclusion substance, the thermoplastic resin constituting the outer shell of the microsphere, workability, and the like, and is not particularly limited. .1 to 1000 hours.
The contact temperature between the microspheres and the solvent in the contact step is appropriately set similarly to the contact time and is not particularly limited. However, considering that it is not advantageous in operation to contact the two at a too low temperature, and that the boiling point of the inclusion substance is usually room temperature or a little higher than that, the contact temperature is, for example, -50 to 100 ° C. The contact temperature is preferably not higher than the boiling point of the inclusion substance.
The contact time and contact temperature in the contact step may be appropriately set in consideration of the thickness of the outer shell of the microsphere.
When the thickness of the outer shell of the microsphere is 2 μm or more (for example, when the microsphere is a heat-expandable microsphere), the contact time in the contact process is 1 to 1000 hours in consideration of improvement in the recovery efficiency of the encapsulated substance. Preferably, it is 10 to 1000 hours, more preferably 100 to 1000 hours. The contact temperature in the contact step is preferably 30 to 100 ° C, more preferably 50 to 100 ° C, and particularly preferably 70 to 100 ° C. As the solvent used in this case, a solvent having a boiling point equal to or higher than the contact temperature between the microspheres and the solvent is desirable, and among the solvents exemplified above, a solvent having a boiling point of 50 ° C. or higher can be mentioned.
Next, when the thickness of the outer shell of the microsphere is less than 2 μm (for example, when the microsphere is a thermally expanded microsphere), the contact time in the contact process is set to 0. It is preferably 1 to 500 hours, and more preferably 0.1 to 100 hours. The contact temperature in the contact step is preferably 0 to 80 ° C. As the solvent used in this case, a solvent having a boiling point equal to or higher than the contact temperature between the microspheres and the solvent is desirable, and among the solvents exemplified above, a solvent having a boiling point of 20 ° C. or higher can be exemplified.
In the encapsulated substance recovery method of the present invention, the encapsulated substance encapsulated in the microspheres can be recovered by bringing the microspheres into contact with the solvent. Although there is no confirmation about the action, it is presumed that the thermoplastic resin constituting the outer shell is swollen or altered by the solvent, and the encapsulated substance permeates and diffuses into the solvent according to the concentration gradient.
The method for recovering an encapsulated substance of the present invention preferably further includes a separation step. The separation step is a step of recovering the inclusion substance from the mixture containing the microspheres obtained in the contact step and a solvent.
Although a separation process may be performed with a contact process and may be performed after a contact process, inclusion substance can be separated and collected in a short time by performing a separation process with a contact process.
Specific means for performing the separation step is not particularly limited, and examples thereof include distillation separation, extraction separation, centrifugation, and adsorption separation of the encapsulated substance.
Distillation separation is a method for separating and recovering the encapsulated substance by utilizing the boiling point difference between the encapsulated substance and the solvent. The boiling point difference is preferably increased in order to increase the working efficiency. The difference in boiling point is, for example, preferably 5 ° C. or higher, more preferably 10 ° C. or higher, and particularly preferably 20 ° C. or higher. In distillation separation, the encapsulated material is once vaporized and then liquefied and separated by a cooling device. However, in consideration of the fact that the boiling point of the encapsulated material is usually room temperature or slightly higher than that, a cooling device or It is preferable to control the temperature of the refrigerant used in the liquefied inclusion substance reservoir or the like to be low. The temperature difference between the temperature of the refrigerant and the boiling point of the inclusion substance is, for example, preferably 30 ° C. or higher, more preferably 50 ° C. or higher, and particularly preferably 100 ° C. or higher.
Extraction separation and centrifugation are both methods of separating and recovering using the property that the inclusion substance and the solvent are phase-separated. When performing extraction separation or centrifugation, the solvent preferably has a property of phase separation when mixed with an inclusion substance. Examples of the solvent include water; alcohols such as methanol and ethanol. When phase separation is not easily performed by extraction separation, centrifugation may be performed to separate the inclusion substance and the solvent from each other. The inclusion substance phase-separated by extraction separation or centrifugation is separated and recovered through a liquid separation operation such as decantation.
Adsorption separation is a method in which vaporized substances are captured and collected by an adsorption unit using an adsorbent such as activated carbon. The substance trapped in the adsorption unit is desorbed and regenerated by steam, and liquefied and recovered by deep-cooling condensation.
In the contact step and the separation step, the mixture containing the microspheres and the solvent may or may not be stirred. However, if the mixture is stirred, the contact efficiency between the microspheres and the solvent is considered to increase. There is no limitation in particular about the stirrer used for the said stirring, For example, common stirrers, such as a homomixer and a line mixer, can be mentioned. There is no particular limitation on the stirring speed.
In performing the contact step and the separation step, the pressure atmosphere is not particularly limited, and may be performed under any pressure of reduced pressure, normal pressure, or increased pressure.
Next, a novel microsphere that can be obtained after the contacting step will be described.
[New microsphere]
The novel microsphere of the present invention (hereinafter sometimes referred to as microsphere a) is a microsphere that can be obtained after the contacting step in the above-described collection method and has a thermoplastic resin as an outer shell.
The microsphere a is a novel microsphere in which a solvent is included in the outer shell instead of the inclusion substance. In the microsphere a, at least the solvent is included, but the inclusion substance remaining without being recovered may be included together with the solvent.
The dried microspheres a may be isolated by removing the solvent from the mixture after the contact step, but considering that no aggregation or fusion occurs, it is better to handle the microspheres in a wet state with a liquid. preferable.
As the liquid, the solvent described in the above recovery method can be used as it is, but depending on the use of the microspheres a, dibutyl phthalate, diisooctyl phthalate, dioctyl adipate, tricresyl phosphate, triethyl citrate, Plasticizers such as acetyltributyl citrate and octyl alcohol (when used for plastics, elastomers, sealants, paints, etc.); monomers such as dicyclopentadiene and styrene (when used for lightweight foamed molded products and adhesives); An ionic surfactant, alkylene glycol, polyalkylene glycol, glycerin, silicone oil, liquid paraffin, fats and the like may be used as the liquid. By replacing the solvent in the mixture after the contacting step with a liquid, the microspheres a can be made wet with the liquid.
The average particle size of the microspheres a is not particularly limited, but when the microspheres are in a wet state, it is preferably 1 to 1000 μm, more preferably 5 to 800 μm, particularly preferably 10 to 500 μm, and most preferably 1 to 150 μm.
The true specific gravity of the microsphere a is not particularly limited, but is preferably 0.001 to 1.5 g / cc, more preferably 0.001 to 1.0 g / cc when the microsphere a is in a dried state. Particularly preferred is 0.001 to 0.8 g / cc.
With respect to the use of the microsphere a, any application that uses various characteristics of the above-described thermally expandable microspheres or thermally expanded microspheres, or an application that uses the fact that the microsphere a is in the form of fine particles may be used. There is no particular limitation. The microspheres a may be used as fillers for organic materials such as resins and inorganic materials, such as extruded cement molded products, fillers for sealing agents, fillers for resin clay, reinforcing fillers for ceramic siding, wood fiber boards Reinforcing fillers, hand soap and industrial detergent abrasives, anti-blocking agents, smoothness-imparting agents, lightweight aggregate substitutes, porosity-imparting agents, fluidizing agents, dust-preventing agents, greening accelerators, slope erosion An inhibitor etc. are mentioned.

The present invention will be described in detail in the following examples and comparative examples, but the present invention is not limited to these examples.
(Measurement method and definition)
[Measurement of average particle size and particle size distribution]
As a measuring apparatus, a laser diffraction particle size distribution measuring apparatus (HEROS & RODOS manufactured by SYMPATEC) was used. The dispersion pressure of the dry dispersion unit was 5.0 bar and the degree of vacuum was 5.0 mbar, measured by a dry measurement method, and the D50 value was taken as the average particle size.
[Measurement of true specific gravity]
The true specific gravity was measured by a liquid displacement method (Archimedes method) using isopropyl alcohol at a temperature of 25 ° C.
[Measurement of moisture content of thermally expandable microspheres]
As a measuring apparatus, a Karl Fischer moisture meter (MKA-510N type, manufactured by Kyoto Electronics Industry Co., Ltd.) was used for measurement.
[Measurement of encapsulation rate of foaming agent enclosed in thermally expandable microspheres]
1.0 g of thermally expandable microspheres were placed in a stainless steel evaporation dish having a diameter of 80 mm and a depth of 15 mm, and the weight (W ₁ ) was measured. 30 ml of acetonitrile was added and dispersed uniformly, left at room temperature for 30 minutes, then heated at 120 ° C. for 2 hours, and the weight (W ₂ ) after drying was measured. The encapsulation rate of the foaming agent is calculated by the following formula.
Inclusion rate (% by weight) = (W ₁ −W ₂ ) (g) /1.0 (g) × 100− (water content) (% by weight)
(In the formula, the moisture content is measured by the above method.)
[Internal retention rate]
The encapsulating rate of the foaming agent is the ratio of the encapsulating rate (G ₂ ) of the foaming agent after expansion to the encapsulating rate (G ₁ ) of the foaming agent before expansion, and is calculated by the following formula.
Inclusion retention rate (%) = G ₂ / G ₁ × 100
[Measurement of (re) expansion start temperature and maximum (re) expansion temperature]
As a measuring device, DMA (DMA Q800 type, manufactured by TA instruments) was used. Place 0.5 mg of thermally expandable microspheres (or thermally expanded microspheres) in an aluminum cup with a diameter of 6.0 mm and a depth of 4.8 mm, and place an aluminum lid with a diameter of 5.6 mm and a thickness of 0.1 mm on it. Samples were prepared. The sample height (H ₁ ) was measured in a state where a force of 0.01 N was applied to the sample from above with a pressurizer. In a state where a force of 0.01 N was applied by a pressurizer, heating was performed from 20 to 300 ° C. at a rate of temperature increase of 10 ° C./min, and the displacement of the pressurizer in the vertical direction was measured. The displacement start temperature in the positive direction was defined as the (re) expansion start temperature, and the temperature when the maximum displacement amount (H ₂ ) was indicated was defined as the maximum (re) expansion temperature. The (re) expansion magnification (E) at the maximum (re) expansion temperature is calculated by the following calculation formula.
E (%) = H ₂ / H ₁ × 100
[Production Example 1]
To 500 g of ion-exchanged water, 150 g of sodium chloride, 3.0 g of adipic acid-diethanolamine condensate, 20 g of colloidal silica (active ingredient amount: 20%) and 0.15 g of sodium nitrite are added and mixed uniformly. It was set as the water phase.
200 g of acrylonitrile, 45 g of methacrylonitrile, 75 g of methacrylic acid, 1.2 g of trimethylolpropane trimethacrylate, 2.0 g of azobisisobutyronitrile and 150 g of C ₃ F ₇ OCH ₃ (encapsulated substance, foaming agent) are mixed and stirred. This was dissolved to make an oil phase.
The aqueous phase and the oil phase were mixed, premixed with a homomixer at 3,000 rpm for 2 minutes, and stirred at 10,000 rpm for 2 minutes to form a suspension. This was transferred to a reactor, purged with nitrogen, and polymerized at 61 ° C. for 20 hours with stirring. After polymerization, the polymerization product was filtered and dried, and the resulting thermally expandable microspheres were designated as microspheres 1. Although the ignition source was brought close to the thermally expandable microsphere, it did not burn.
[Production Example 2]
The microspheres 1 obtained in Production Example 1 were heated and expanded by the above-described method for producing thermally expanded microspheres (manufacturing method (A) to produce thermally expanded microspheres. These thermally expanded microspheres. Was used as a member of a run flat tire, and a run test of the run flat tire was performed, and microspheres that were thermally expanded after the test (thermally expanded microspheres after the run test) were used. (Hereinafter, sometimes referred to simply as “microsphere 2”), and the physical properties thereof were measured. The average particle diameter was 90 μm, the true specific gravity was 0.028 g / cc, the encapsulation rate was 32%, the encapsulation retention rate was 98%, and re-expansion started. The content (25 ° C.) of microspheres having a temperature of 132 ° C., a maximum re-expansion temperature of 202 ° C., a re-expansion ratio of 211%, and a true specific gravity of 0.79 g / cc or more was 0.8% by weight.
[Production Example 3]
The heat-expandable microspheres obtained by polymerization in the same manner as in Production Example 1 except that 64 g of isopentane was used as the inclusion substance instead of 150 g of C ₃ F ₇ OCH ₃ in Production Example 1 were designated as Microsphere 3.
[Production Example 4]
The microspheres 3 obtained in Production Example 3 were heated and expanded in the same manner as in Production Example 2 to produce thermally expanded microspheres (microspheres 4).
[Production Example 5]
The microsphere 1 obtained in Production Example 1 and carbon black (manufactured by Lion Co., Ltd., product name: Ketjen Black ECP600JD, average particle size: 34 nm) at a weight ratio of 9: 1, a super mixer (manufactured by Kawata Co., Ltd.) ) To obtain thermally expanded microspheres having carbon black adhered to the outer surface. The obtained thermally expandable microspheres were heated and expanded in the same manner as in Production Example 2 to manufacture thermally expanded microspheres (microspheres 5).
[Example 1]
0.05 g of the microspheres 2 obtained in Production Example 2 were weighed and mixed and dispersed in 20 mL of ethanol. The resulting mixture was left in the refrigerator overnight and then extracted with hexane. When the obtained hexane phase was analyzed by gas chromatography (GC17A manufactured by Shimadzu Corporation), C ₃ F ₇ OCH ₃ was detected.
The ethanol used above was replaced with acetonitrile, toluene, dimethylformamide, weak alkaline water (pH 9), and strong alkaline water (pH 12), respectively, and the same operation as above was performed. In each, C ₃ F ₇ OCH ₃ was detected.
[Example 2]
40 g of the microspheres 2 obtained in Production Example 2 were weighed and 1 L of ethanol was mixed and dispersed for 10 minutes using a homomixer. The obtained mixture was supplied to a 2 L eggplant flask, and the heat source for heating the flask was set to 40 ° C. and distilled at atmospheric pressure. This distillation operation was performed for 30 minutes, and the distillate (7.7 mL) collected in the cooling tube cooled with liquid nitrogen was analyzed by gas chromatography to confirm that it was C ₃ F ₇ OCH _3. Was 90%. A new microsphere was obtained after collection.
Example 3
In Example 2, C ₃ F ₇ OCH ₃ was recovered in the same manner as in Example 2 except that strong alkaline water (pH 12) was used instead of ethanol. The recovery rate was 90%. In addition, the novel microsphere obtained after collection | recovery hold | maintained spherical shape, and the strong alkaline water was included in the outer shell.
Example 4
40 g of the microspheres 3 obtained in Production Example 3 were weighed, and 1 L of ethanol was mixed and dispersed for 10 minutes using a homomixer. The obtained mixture was supplied to a 2 L eggplant flask, and the heat source for heating the flask was set to 30 ° C. and distilled at atmospheric pressure. This distillation operation was performed for 30 minutes, and the distillate (22 mL) accumulated in the cooling tube cooled with liquid nitrogen was analyzed by gas chromatography to confirm that it was isopentane. The recovery rate was 91%. A new microsphere was obtained after collection.
Example 5
In Example 4 above, isopentane was recovered in the same manner as in Example 4 except that strong alkaline water (pH 12) was used instead of ethanol. The recovery rate was 91%. In addition, the novel microsphere obtained after collection | recovery hold | maintained spherical shape, and the strong alkaline water was included in the outer shell.
Example 6
200 g of the microspheres 1 obtained in Production Example 1 were weighed, and strong alkaline water (pH 12) was mixed and dispersed for 10 minutes using a homomixer. The obtained mixture was supplied to an eggplant flask having a capacity of 2 L, and a heat source for heating the flask was set at 80 ° C. and distilled at atmospheric pressure. This distillation operation was performed for 120 minutes, and the distillate (37 mL) collected in the cooling tube cooled with liquid nitrogen was analyzed by gas chromatography to confirm that it was C ₃ F ₇ OCH _3. %Met. In addition, the novel microsphere obtained after collection | recovery hold | maintained spherical shape, and the strong alkaline water was included in the outer shell.
Example 7
200 g of the microspheres 3 obtained in Production Example 3 were weighed, and strong alkaline water (pH 12) was mixed and dispersed for 10 minutes using a homomixer. The obtained mixture was supplied to an eggplant flask having a capacity of 2 L, and a heat source for heating the flask was set at 80 ° C. and distilled at atmospheric pressure. This distillation operation was performed for 120 minutes, and the distillate (90 mL) collected in the cooling tube cooled with liquid nitrogen was analyzed by gas chromatography to confirm that it was C ₃ F ₇ OCH _3. %Met. In addition, the novel microsphere obtained after collection | recovery hold | maintained spherical shape, and the strong alkaline water was included in the outer shell. The novel microspheres were dried at 40 ° C. for 20 hours, and the true specific gravity of the crushed flakes was measured and found to be 0.97 g / cc.
Example 8
40 g of the microspheres 5 obtained in Production Example 5 were weighed, and 1 L of ethanol was mixed and dispersed for 10 minutes using a homomixer. The obtained mixture was supplied to a 2 L eggplant flask, and the heat source for heating the flask was set to 40 ° C. and distilled at atmospheric pressure. This distillation operation was performed for 30 minutes, and the distillate (7.7 mL) collected in the cooling tube cooled with liquid nitrogen was analyzed by gas chromatography to confirm that it was C ₃ F ₇ OCH _3. Was 90%. A new microsphere was obtained after collection.
Example 9
In Example 8 above, C ₃ F ₇ OCH ₃ was recovered in the same manner as in Example 2 except that strong alkaline water (pH 12) was used instead of ethanol. The recovery rate was 91%. In addition, the novel microsphere obtained after collection | recovery hold | maintained spherical shape, and the strong alkaline water was included in the outer shell.

According to the method for recovering an encapsulated substance of the present invention, the encapsulated substance can be easily and efficiently recovered from a microsphere composed of an outer shell made of a thermoplastic resin and an encapsulated substance contained therein.
The novel microspheres of the present invention are new microspheres that can be obtained after recovering the encapsulated substance in the above recovery method and have not been known so far.

Claims (11)

A microsphere composed of an outer shell made of a thermoplastic resin and an inclusion substance contained in the outer shell and having a boiling point equal to or lower than the softening point of the thermoplastic resin is brought into contact with a solvent, and the inclusion substance inside the outer shell is brought into contact with the outer shell. It moved out of the solvent, including contacting step Ru done without damaging the outer shell, the method of recovering the entrapped substance. The method for recovering an inclusion substance according to claim 1, wherein the thermoplastic resin is a resin obtained by polymerizing a monomer mixture containing a crosslinking agent. The contacting step in the resulting microspheres and further comprising a mixture containing a solvent separation step of recovering the entrapped substance, a method of recovering the entrapped substance according to claim 1 or 2. The method for recovering an encapsulated substance according to claim 3 , wherein the separation step is performed together with the contact step. The thermoplastic resin is at least one radical selected from nitrile monomers, (meth) acrylate monomers, carboxyl group-containing monomers, styrene monomers, vinyl acetate and vinylidene chloride. The method for recovering an encapsulated substance according to any one of claims 1 to 4 , which is a resin obtained by polymerizing a monomer mixture containing a polymerizable monomer. The method for recovering an inclusion substance according to any one of claims 1 to 5 , wherein the inclusion substance includes at least a fluorine-containing compound having 2 to 10 carbon atoms, which has an ether structure and does not contain a chlorine atom and a bromine atom. The method for recovering an encapsulated substance according to any one of claims 1 to 6 , wherein the solvent is a polar solvent. The method for recovering an encapsulated substance according to any one of claims 1 to 7 , wherein the microsphere is a microsphere filled in a hollow portion of an assembly of a tire and a rim. The method for recovering an encapsulated substance according to any one of claims 1 to 8 , wherein the microsphere can be obtained after the contacting step and uses the thermoplastic resin as an outer shell. The novel microsphere according to claim 9 , wherein the solvent is encapsulated in the outer shell. In a wet state in a liquid, novel microspheres according to claim 9 or 1 0.