JP2004323715A - Foamed polyimide molded product and method for producing the same - Google Patents
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Abstract
Description
【０００１】
この発明は、発泡ポリイミド成型体およびその製法に関し、さらに詳しくは耐熱性を有するとともに任意の形状に成型された発泡ポリイミド成型体およびその製法に関する。
【０００２】
【従来技術】
従来、発泡体としては、ウレタン系、ポリスチレン系、ポリオレフィン系のものがよく知られている。これらの発泡体から成型体とする場合、発泡体をチップ化してこれを再度バインダ−によって椅子のクッションや工業用断熱材として使用されている。
これらの発泡成型体は、耐熱性が１００℃程度であり、使用温度範囲が限定されていた。
【０００３】
そこで、高温下、特に３００℃以上の温度で使用可能な耐熱性を有する工業用断熱発泡材が求められてきた。
このため、耐熱性発泡体としてポリイミド系が種々検討され、ポリイミド成型体が提案された（特許文献１、特許文献２、特許文献３、特許文献４、特許文献５）。
【０００４】
【特許文献１】
米国特許第４２４１１９３号明細書
【特許文献２】
特開昭６１−１９５１２６号公報
【特許文献３】
特開平１−３１３５３７号公報
【特許文献４】
特開平２−２４３２６号公報
【特許文献５】
特開平４−２１１４４０号公報
【０００５】
しかし、これらの発泡ポリイミド成型体は、発泡と成型とを同時に行うことによって得られるものであり、形状や大きさに制限を受け、ポリイミド発泡成型体の用途に制限を受ける。
【０００６】
【発明が解決しようとする課題】
この発明の目的は、耐熱性を有するとともに任意の形状に成型された発泡ポリイミド成型体およびその製法を提供することである。
【０００７】
【課題を解決するための手段】
この発明は、予め発泡されたポリイミド樹脂塊を破砕し、これを耐熱性バインダ−と混合し、この混合物を所定の型枠に投入後、所定の密度まで加圧、焼成してなる発泡ポリイミド成型体に関する。
また、この発明は、予め発泡されたポリイミド樹脂塊を破砕し、これを耐熱性バインダ−と混合し、この混合物を所定の型枠に投入後、所定の密度まで加圧して成型して、焼成することを特徴とする発泡ポリイミド成型体の製法に関する。この明細書において、耐熱性バインダ−とは３００℃で６０分間の加熱試験後に劣化が実質的に認められないものをいう。
【０００８】
【発明の実施の形態】
この発明の実施の形態を次に示す。
１）３００℃で６０分間の耐熱性試験を行って外観変化がなく、質量減少が１％以下の耐熱性を有する上記の発泡ポリイミド成型体。
２）密度が０．０１〜０．８ｇ／ｃｍ３である上記の発泡ポリイミド成型体。
３）形状がシ−ト状、パイプ状、柱状、キュ−ブ状および箱状のいずれかである上記の発泡ポリイミド成型体。
４）パイプの形状を有し、内径が１０〜１０００ｍｍで、外径が１５〜２０００ｍｍである上記の発泡ポリイミド成型体。
【０００９】
５）辺Ａ、Ｂ、Ｃからなるブロックの形状を有し、Ａ、Ｂ、Ｃが各々独立に１０〜３０００ｍｍである上記の発泡ポリイミド成型体。
６）予め発泡されたポリイミド樹脂塊が、芳香族テトラカルボン酸成分として２，３，３’，４’−ビフェニルテトラカルボン酸成分を必須成分として得られるポリマ−である上記の発泡ポリイミド成型体の製法。
７）耐熱性バインダ−が、ポリアミック酸である上記の発泡ポリイミド成型体の製法。
【００１０】
８）耐熱性バインダ−が、芳香族テトラカルボン酸成分として２，３，３’，４’−ビフェニルテトラカルボン酸成分を必須成分として得られるポリアミック酸である上記の発泡ポリイミド成型体の製法。
９）耐熱性バインダ−が、使用時の温度で５０センチポイズ以下の溶液粘度である上記の発泡ポリイミド成型体の製法。
１０）耐熱性バインダ−が、予め発泡されたポリイミド樹脂塊の破砕物に対して２〜３０質量％の割合で混合される上記の発泡ポリイミド成型体の製法。
【００１１】
１１）予め発泡されたポリイミド樹脂塊が、０．０００５〜０．１ｇ／ｃｍ３の密度を有するものである上記の発泡ポリイミド成型体の製法。
１２）発泡ポリイミド成型体が、シ−ト状、パイプ状、柱状、キュ−ブ状、箱状などの任意の形状である上記の発泡ポリイミド成型体の製法。
【００１２】
この発明において予め発泡されたポリイミド樹脂塊は、好適には、芳香族テトラカルボン酸二無水物とアルコ−ルとを反応させた芳香族テトラカルボン酸のハ−フエステルとジアミンとアルコ−ルとを含むポリイミド発泡前駆体混合物を蒸発乾固、粉末化し、予備成型して適当なグリ−ン体を作成し、さらに加熱して発泡させることによって得られる。前記の加熱の前に、マイクロ波加熱を行ってもよい。
【００１３】
前記の芳香族テトラカルボン酸二無水物としては、２，３，３’，４’−ビフェニルテトラカルボン酸二無水物、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物、ピロメリット酸二無水物、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物、ビス（３，４−ジカルボキシフェニル）エ−テル二無水物、２，３，６，７−ナフタレンテトラカルボン酸二無水物、１，２，５，６−ナフタレンテトラカルボン酸二無水物、１，２，４，５−ナフタレンテトラカルボン酸二無水物、１，４，５，８−ナフタレンテトラカルボン酸二無水物、２，２−ビス（２，５−ジカルボキシフェニル）プロパン二無水物、１，１−ビス（２，３−ジカルボキシフェニル）エタン二無水物、１，１−ビス（３，４−ジカルボキシフェニル）スルホン二無水物、１，３−ビス（３，４−ジカルボキシフェニル）−１，１，３，３−テトラメチルジシロキサン二無水物などが挙げられる。
特に、２，３，３’，４’−ビフェニルテトラカルボン酸二無水物を５０％以上含むものが好ましい。
【００１４】
前記のジアミンとしては、２芳香核ジアミンまでを主成分とすることが好ましく、これによって発泡ポリイミドのＴｇが３００℃以上を達成することが容易になる。多置換アミン成分は高温での発泡の収縮防止、発泡強度（発泡中に割れにくい）増大のために、必須なものではないが一部含まれている方が好ましい。ジアミノジシロキサンは界面活性剤的に作用し、発泡均一化のために０．１〜１０モル％の範囲、好ましくは０．２〜５モル％は必要である。少量では発泡が均一化しづらく、多量ではＴｇ低下および熱安定性の低下をまねく。
【００１５】
前記のポリイミド発泡前駆体混合物として、好適には２，３，３’，４’−ビフェニルテトラカルボン酸二無水物（以下、ａ−ＢＰＤＡと略記することもある。）のハ−フエステルと芳香族ジアミン、例えば、ｐ−フェニレンジアミン（以下、ＰＰＤと略記することもある。）および／または４，４’−ジアミノジフェニルエ−テル（以下、ＯＤＡと略記することもある。）と、発泡均一化のための成分、例えばジアミノジシロキサンおよびさらに必要ならば分子内に３個以上のアミノ基を有するアミン化合物、例えば芳香族トリアミン化合物または芳香族テトラアミン化合物、特にテトラアミノビフェニルをエステル化溶媒、例えばメタノ−ル、エタノ−ル、ｎ−プロパノ−ル、ｎ−ブタノ−ルなどの低級一級アルコ−ル、好適にはメタノ−ルあるいはエタノ−ルと均一混合して溶解して、全量中の不揮発成分量が１０％〜５０％程度の混合物として得ることができる。
【００１６】
前記のポリイミド発泡前駆体混合物には、１，２−ジメチルイミダゾ−ル、ベンズイミダゾ−ル、イソキノリン、置換ピリジンなどのイミド化触媒を加えてもよい。
また、他の公知の添加剤、例えば、無機フィラ−、無機あるいは有機顔料などを加えてもよい。
【００１７】
上記混合物を蒸発乾固し、粉末化を行う工程においては、実験室的にはエバポレ−タ、工業的にはスプレ−ドライヤ−などが使用できる。この蒸発温度は１００℃未満、好ましくは８０℃以下の状態に保たれることが好ましい。高温乾燥では発泡性が極端に低下する。乾燥の際、常圧でも、加圧下でも、あるいは減圧下でもよい。
【００１８】
前記の適当なグリ−ン体を成型する工程においては、例えば、室温での圧縮成形、スラリ−溶液として流延乾固、マイクロ波に不活性な容器への充填を行う。この際に、蓋はしなくともよい（すなわち、完全に固める必要はない。）。概略均一な状態のグリ−ン体であれば、発泡時の均一化は達成できる。
【００１９】
前記のマイクロ波加熱による加熱においては、一般的には約２．４５ＧＨｚで行うことが好ましい。これは日本の国内法（電波法）に基く。粉末重量当たりのマイクロ波出力を目安とすることが好ましい。これは実験を重ねることによって定義すべきである。例えば、１００ｇ／１ｋＷ程度で約１分で発泡を開始し、２〜３分で発泡は収束する。この状態では非常に脆い発泡体である。
【００２０】
次いでマイクロ波加熱体を熱風等の加熱により、２００℃程度から徐々に昇温する（一応の目安として、１００℃／１０分程度の昇温速度）。最終は加熱によって生成するポリイミドのガラス転位温度（Ｔｇ）＋αの温度にて５〜６０分間、好適には１０分間程度加熱する。
上記の各工程によって加熱発泡することによって、形状は不定形とはなるが、均一な発泡状態の弾力性がありかつ復元力に優れた発泡体が得られる。
【００２１】
前記の方法において、固体状態のポリイミド前駆体の加熱を、発泡のための加熱と熱固定（高分子量化）のための加熱の２段階とすることが好ましい。
また、前記の発泡ポリイミドの製法において、発泡のための加熱を、加熱均一性向上のためにマイクロ波加熱によって行うことが好ましい。
そして、熱固定（高分子量化）のための加熱を、発泡ポリイミドのガラス転移温度（Ｔｇ）以上の温度、好適には３１０℃より高く５００℃以下の温度で５〜６０分間程度加熱して行うことが好ましい。
【００２２】
前記の発泡工程によって得られる発泡されたポリイミド樹脂塊は、発泡倍率を任意に調整することができるが、好適には０．０００５〜０．１ｇ／ｃｍ３の密度を有するものが好ましい。
【００２３】
この発明においては、前記の予め発泡されたポリイミド樹脂塊を破砕し、これを耐熱性バインダ−と混合し、この混合物を所定の形状を有する型枠に投入後、所定の密度まで加圧、焼成することによって、発泡ポリイミド成型体を得る。
【００２４】
前記の方法におけるポリイミド樹脂発泡塊を破砕する方法としては、特に制限はなく、例えばプラスティック成形体の解砕機を適宜使用することができる。
前記の方法によって、ポリイミド樹脂発泡塊として球に換算してφ（直径）が１ｍｍ〜５０ｍｍ程度の大きさの破砕品とすることが好ましい。
【００２５】
この発明においては、前記の破砕品を耐熱性バインダ−と混合することが重要である。
前記の耐熱性バインダ−としては、ポリイミドの耐熱性を維持しつつバインダ−として機能する必要性からポリアミック酸が好適である。
特に、前記のバインダ−用ポリアミック酸として、芳香族テトラカルボン酸成分、好適には非対称性の芳香族テトラカルボン酸成分と芳香族ジアミンとから得られるポリアミック酸あるいは芳香族テトラカルボン酸成分とメタ置換の芳香族ジアミンとから得られるポリアミック酸などの、耐熱性の熱融着性ポリイミドを与えるポリアミック酸が好適である。
前記の方法において、バインダ−のポリアミック酸はポリアミック酸の粉末状で使用してもよく、あるいは溶媒溶液として使用してもよい。ポリアミック酸の溶媒溶液として使用する場合にはポリアミック酸の濃度は１〜２０質量％程度であることが適当である。
【００２６】
前記の芳香族テトラカルボン酸成分として、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物、２，３，３’，４’−ビフェニルテトラカルボン酸二無水物、１，２，３’，４’−ベンゾフェノンテトラカルボン酸二無水物、１，２，３’，４’−ジフェニルエ−テルテトラカルボン酸二無水物、１，２，３’，４’−ジフェニルメタンテトラカルボン酸二無水物やこれらの酸またはエステル、好適には非対称性芳香族テトラカルボン酸成分、例えば２，３，３’，４’−ビフェニルテトラカルボン酸二無水物、１，２，３’，４’−ベンゾフェノンテトラカルボン酸二無水物、１，２，３’，４’−ジフェニルエ−テルテトラカルボン酸二無水物、１，２，３’，４’−ジフェニルメタンテトラカルボン酸二無水物やこれらの酸またはエステル、特に２，３，３’，４’−ビフェニルテトラカルボン酸二無水物を挙げることができる。
【００２７】
前記の芳香族テトラカルボン酸成分と反応させる芳香族ジアミンとしては、特に制限はないがベンゼン環を３〜４個有する芳香族ジアミン、例えば１，３−ビス（４−アミノフェノキシベンゼン）、１，３−ビス（４−アミノフェノキシ）ビフェニル、好適には１，３−ビス（４−アミノフェノキシベンゼン）を挙げることができる。前記の非対称性の芳香族テトラカルボン酸二無水物の８０モル％以下を対称性の芳香族テトラカルボン酸成分で置き換えてもよく、また前記のベンゼン環を３〜４個有する芳香族ジアミンの８０モル％以下をベンゼン環を１〜２個有する芳香族ジアミンで置き換えてもよい。
【００２８】
前記の方法において、耐熱性バインダ−の使用量は、固形分換算でポリイミド樹脂発泡塊の破砕品１００質量部に対して、２〜３０質量部であることが好ましい。
前記のポリイミド樹脂発泡塊の破砕品と耐熱性バインダ−とを混合する方法としては特に制限はなく、例えばポリイミド樹脂発泡塊の破砕品と耐熱性バインダ−の粉末とをニ−ダ−で混合する方法、あるいはポリイミド樹脂発泡塊の破砕品に耐熱性バインダ−の溶液を噴霧する方法が挙げられる。
【００２９】
この発明においては、ポリイミド樹脂発泡塊の破砕品と耐熱性バインダ−との混合物を所定の形状を有する型枠に投入後、所定の密度まで加圧、焼成することによって、発泡ポリイミド成型体を得ることができる。
前記の型枠としては、耐熱性素材製、例えば金属製、好適にはステンレス製の型枠が使用できる。
【００３０】
前記の加圧、焼成は、例えば型枠内に耐熱性バインダ−を混合したポリイミド樹脂発泡塊の破砕品をガス抜きを備えたステンレス製の型枠内に投入し、押さえ蓋で所定寸法（例えば高さ）に圧縮し、押さえ蓋を固定した後、２５０℃以上でポリイミド発泡体のガラス転位温度以下の温度、好適には３００℃以上４００℃以下の温度に加熱した加熱炉内に１０〜１２０分間程度置くことによって行うことが好ましい。
【００３１】
この発明のポリイミド成型体は、好適には３００℃で６０分間の耐熱性試験を行って外観変化がなく、質量減少が１％以下の耐熱性を有するものである。
また、この発明のポリイミド成型体は、成型条件を選択することによって、密度が０．０１〜０．８ｇ／ｃｍ３である。
また、この発明の発泡ポリイミド成型体は、型枠を選択することによって、形状がシ−ト状、パイプ状、柱状、キュ−ブ状、箱状のいずれでもするることができ、特にパイプの形状を有し、内径が１０〜１０００ｍｍで、外径が１５〜２０００ｍｍであるもの、あるいは辺がＡ、Ｂ、Ｃからなるブロックの形状を有し、Ａ、Ｂ、Ｃが各々独立に１０〜３０００ｍｍである発泡ポリイミド成型体とすることができる。
【００３２】
【実施例】
実施例および比較例における物性測定法を以下に示す。
ガラス転移温度：ＤＳＣ（セイコ−電子工業社製、ＤＳＣ２２０Ｃ）を用い、Ｎ２雰囲気下、２０℃／分の昇温速度にて測定。
発泡倍率：真密度／見かけ密度より算出。
真密度は、同組成のポリイミドフィルムを常法により作製し、密度勾配管を
用いて測定した値を用いた。
見かけ密度は、立方体または四角形シ−ト状に切断したものをノギスにより計測して体積を求め、また天秤により質量を計測し、質量／体積により求
めた。
引張強度：１５０ｍｍＬ×２５ｍｍＷ×１０ｍｍＴの短冊状サンプルを切り出し、テンシロン引張試験機（オリエンテック社製）を使用し、引張速度１０ｍｍ／分で測定した。
引張伸び：引張強度測定試験と同様のサンプル、測定機および測定条件で測定した。
耐熱試験：オ−ブン中に６０分放置後の外観、質量変化を求めた。
【００３３】
以下の記載において、各略号は次の化合物を意味する。
ａ−ＢＰＤＡ：２，３，３’，４’−ビフェニルテトラカルボン酸二無水物
ＢＴＤＡ：３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物
ＰＰＤ：ｐ−フェニレンジアミン
ＯＤＡ：４，４’−ジアミノジフェニルエ−テル
ＴＰＥ−Ｒ：１，３−ビス（４−アミノフェノキシ）ベンゼン
ＤＡＤＳｉ：１，３−ビス（３−アミノプロピル）テトラメチルジシロキサン
ＤＭＺ：１，２−ジメチルイミダゾ−ル
【００３４】
実施例１
５００ｍｌナス型フラスコにａ−ＢＰＤＡ１８０ｍｍｏｌ、メタノ−ル７０ｇ、触媒としてＤＭＺ２．４４ｇを仕込み、９０℃オイルバス中で還流させながら９０分間加熱攪拌を行い、均一溶液とした。次に、この溶液を３０℃以下に冷却した後、ＰＰＤ１８９ｍｍｏｌ、ＤＡＤＳｉ２ｍｍｏｌ、メタノ−ル３０ｇを加え均一溶液とした。この溶液をエバポレ−タ−で濃縮し、６０℃減圧乾燥して固形物を得た。
この固形物を粉砕粉末化して圧縮成型機を使用してグリ−ン体を成型し、このグリ−ン体をマイクロ波加熱装置を使用して、発泡倍率が１３０倍である発泡体を得た。この発泡体を４５０℃で１５分間加熱し、ポリイミド発泡体を得た。
このポリイミド発泡体を解砕機で略φ５ｍｍ径の大きさに解砕したチップを得た。
【００３５】
このチップに、耐熱性バインダ−としてａ−ＢＰＤＡと１，３−ビス（４−アミノフェノキシ）ベンゼンとをジメチルアセトアミド中で５．５質量％の濃度で重合して得た粘度が９ｃｐのポリアミック酸溶液を使用し、該チップ１５ｇに対して該耐熱性バインダ−溶液２７ｇを噴霧機を使用し該チップを攪拌しながら噴霧し、約１０分間混合攪拌して、チップと耐熱性バインダ−との混合物を得た。この混合物のチップを高さ２５０ｍｍ、幅１５０ｍｍ、長さ２００ｍｍのステンレス製の型に投入し、ガス抜きを備えた押さえ蓋で高さが２００ｍｍまで圧縮し、押さえ蓋を固定した。この容器をオ−ブン中に投入し、３５０℃で３０分間焼成した。冷却後、型から発泡ポリイミド成型体を取り出した。
このポリイミド発泡成型体について、密度、引張強度、３００℃オ−ブン中に６０分間放置後の外観、質量変化を調べた。結果をまとめて表１に示す。
【００３６】
実施例２
ジアミン成分としてＤＡＤＥを使用した他は実施例１と同様にして、発泡倍率１４０倍の発泡ポリイミドを得た。この発泡ポリイミド発泡体を使用した他は実施例１と同様にして、発泡ポリイミド成型体を得た。
このポリイミド発泡成型体について、密度、引張強度、３００℃オ−ブン中に６０分間放置後の外観、質量変化を調べた。結果をまとめて表１に示す。
【００３７】
実施例３
発泡倍率を変えた他は実施例１と同様にして、密度が０．０１５ｇ／ｃｍ３の発泡ポリイミド成型体を得た。
このポリイミド発泡成型体について、密度、引張強度、３００℃オ−ブン中に６０分間放置後の外観、質量変化を調べた。結果をまとめて表１に示す。
【００３８】
実施例４
耐熱性バインダ−として、芳香族テトラカルボン酸成分としてａ−ＢＰＤＡ８０ｍｏｌとｓ−ＢＰＤＡ２０ｍｏｌ％との組成とした他は実施例１と同様にして得られたポリアミック酸溶液を使用した他は実施例１と同様にして、発泡ポリイミド成型体を得た。
このポリイミド発泡成型体について、密度、引張強度、３００℃オ−ブン中に６０分間放置後の外観、質量変化を調べた。結果をまとめて表１に示す。
【００３９】
実施例５
型枠の形状を変えた他は実施例１と同様にして、図２に示す寸法の発泡ポリイミド成型体を得た。
このポリイミド発泡成型体について、密度、引張強度、３００℃オ−ブン中に６０分間放置後の外観、質量変化を調べた。結果をまとめて表１に示す。
【００４０】
比較例１
耐熱性バインダ−として、ウレタン系バインダ−を使用し、バインダ−量としてチップに対して１０質量％の量で噴霧し、実施例１に記載の型枠を使用して、密度０．０３ｇ／ｃｍ３の成型体を成型し、次いで１００℃のスチ−ムで加熱しウレタンバインダ−を硬化させて、ウレタンバインダ−製発泡ポリイミド成型体を得た。常法に従って６０℃雰囲気下で乾燥した後、評価を行った。。結果をまとめて表１に示す。
【００４１】
【表１】
表１から、実施例１〜５によれば、密度が０．０１ｇ／ｃｍ３以上０．１ｇ／ｃｍ３以下で、３００℃で６０分間の耐熱試験によって、外観変化なく、質量減少が１％以下の耐熱性を有するポリイミド発泡成型体が得られたことを示している。
これに対し、耐熱性の低いバインダ−を使用した比較例１によれば、上記の耐熱性試験によって、一部炭化して外観変化があり、質量減少が１％より多い耐熱性を有さないポリイミド発泡成型体が得られたことを示している。
【００４３】
【発明の効果】
この発明によれば、耐熱性を有するとともに任意の形状に成型された発泡ポリイミド成型体を得ることができる。
また、この発明の方法によれば、簡単な操作で前記の特長を有する発泡ポリイミドを製造することができる。
【図面の簡単な説明】
【図１】図１は、この発明の一例である発泡ポリイミド成型体の写真である。
【図２】図２は、この発明の一例である実施例５で得られた発泡ポリイミド成型体の寸法である。[0001]
The present invention relates to a foamed polyimide molded article and a method for producing the same, and more particularly to a foamed polyimide molded article having heat resistance and molded into an arbitrary shape, and a method for producing the same.
[0002]
[Prior art]
Conventionally, urethane-based, polystyrene-based, and polyolefin-based foams are well known. When a foam is formed from these foams, the foam is formed into chips, which are again used as binders for chairs or industrial heat insulators by means of a binder.
These foamed molded articles had heat resistance of about 100 ° C., and the operating temperature range was limited.
[0003]
Therefore, there has been a demand for an industrial heat insulating foam material having heat resistance that can be used at high temperatures, particularly at a temperature of 300 ° C. or higher.
For this reason, various types of polyimides have been studied as heat-resistant foams, and polyimide molded articles have been proposed (Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5).
[0004]
[Patent Document 1]
US Pat. No. 4,241,193 [Patent Document 2]
JP-A-61-195126 [Patent Document 3]
Japanese Patent Application Laid-Open No. 1-313537 [Patent Document 4]
JP-A-2-24326 [Patent Document 5]
Japanese Patent Application Laid-Open No. H4-211440
However, these foamed polyimide moldings are obtained by performing foaming and molding at the same time, and are limited in shape and size, and are restricted in applications of the polyimide foam moldings.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a foamed polyimide molded article having heat resistance and molded into an arbitrary shape, and a method for producing the same.
[0007]
[Means for Solving the Problems]
The present invention is a foamed polyimide molding obtained by crushing a foamed polyimide resin mass, mixing the same with a heat-resistant binder, charging the mixture into a predetermined mold, and then pressing and firing to a predetermined density. About the body.
Further, the present invention crushes a pre-foamed polyimide resin mass, mixes it with a heat-resistant binder, puts this mixture into a predetermined mold, presses it to a predetermined density, molds it, and fires it. And a method for producing a foamed polyimide molded article. In this specification, the term "heat-resistant binder" refers to a binder which is substantially not deteriorated after a heating test at 300 ° C. for 60 minutes.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below.
1) The above-mentioned foamed polyimide molded article which has no change in appearance when subjected to a heat resistance test at 300 ° C. for 60 minutes and has a heat resistance of 1% or less in mass loss.
2) The foamed polyimide molded article having a density of 0.01 to 0.8 g / cm 3 .
3) The above-mentioned foamed polyimide molded article having any one of a sheet shape, a pipe shape, a column shape, a cube shape, and a box shape.
4) The above foamed polyimide molded article having a pipe shape, an inner diameter of 10 to 1000 mm, and an outer diameter of 15 to 2000 mm.
[0009]
5) The above foamed polyimide molded article having a block shape composed of sides A, B, and C, wherein A, B, and C are each independently 10 to 3000 mm.
6) The foamed polyimide molded article, wherein the foamed polyimide resin mass is a polymer obtained by using a 2,3,3 ′, 4′-biphenyltetracarboxylic acid component as an essential component as an aromatic tetracarboxylic acid component Manufacturing method.
7) The method for producing the above foamed polyimide molded article in which the heat-resistant binder is a polyamic acid.
[0010]
8) The method for producing a foamed polyimide molded article described above, wherein the heat-resistant binder is a polyamic acid obtained by using a 2,3,3 ′, 4′-biphenyltetracarboxylic acid component as an essential component as an aromatic tetracarboxylic acid component.
9) The method for producing a foamed polyimide molded article in which the heat-resistant binder has a solution viscosity of 50 centipoise or less at the temperature at the time of use.
10) The above-mentioned method for producing a foamed polyimide molded article in which a heat-resistant binder is mixed at a ratio of 2 to 30% by mass based on a crushed product of a foamed polyimide resin mass.
[0011]
11) The above-mentioned method for producing a foamed polyimide molded article, wherein the preliminarily foamed polyimide resin mass has a density of 0.0005 to 0.1 g / cm 3 .
12) The method for producing the above-mentioned foamed polyimide molded article, wherein the foamed polyimide molded article has an arbitrary shape such as a sheet shape, a pipe shape, a column shape, a cube shape, and a box shape.
[0012]
In the present invention, the pre-foamed polyimide resin mass is preferably prepared by reacting a half ester of an aromatic tetracarboxylic acid obtained by reacting an aromatic tetracarboxylic dianhydride with an alcohol, a diamine and an alcohol. The obtained polyimide foam precursor mixture is obtained by evaporating to dryness, pulverizing, preforming to form a suitable green body, and then heating to foam. Prior to the heating, microwave heating may be performed.
[0013]
Examples of the aromatic tetracarboxylic dianhydride include 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, Mellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,4,5-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic Acid dianhydride, 2,2-bis (2,5-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3 , 4-dicarboxyphenyl) sul Emissions dianhydride, 1,3-bis (3,4-carboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride.
In particular, those containing 50% or more of 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride are preferable.
[0014]
As the diamine, it is preferable to use a diaromatic nucleus diamine as a main component, whereby it becomes easy to achieve a Tg of the foamed polyimide of 300 ° C. or higher. The polysubstituted amine component is not essential but is preferably included partially in order to prevent shrinkage of foaming at high temperature and to increase foaming strength (hard to break during foaming). Diaminodisiloxane acts as a surfactant, and is required in the range of 0.1 to 10 mol%, preferably 0.2 to 5 mol%, for uniform foaming. If the amount is small, it is difficult to make the foam uniform, and if the amount is large, the Tg decreases and the thermal stability decreases.
[0015]
As the polyimide foam precursor mixture, preferably, a half ester of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as a-BPDA) and an aromatic ester are used. Foam homogenization with a diamine, for example, p-phenylenediamine (hereinafter sometimes abbreviated as PPD) and / or 4,4′-diaminodiphenyl ether (hereinafter sometimes abbreviated as ODA). For example, diaminodisiloxane and, if necessary, an amine compound having three or more amino groups in the molecule, for example, an aromatic triamine compound or an aromatic tetraamine compound, especially tetraaminobiphenyl, in an esterification solvent such as methanol. -Lower primary alcohols such as ethanol, ethanol, n-propanol and n-butanol, preferably methanol Rui ethanol - dissolved by mixing le and uniform, nonvolatile component content in the total amount can be obtained as a mixture of approximately 10% to 50%.
[0016]
An imidization catalyst such as 1,2-dimethylimidazole, benzimidazole, isoquinoline, or substituted pyridine may be added to the polyimide foam precursor mixture.
Further, other known additives such as an inorganic filler, an inorganic or organic pigment, and the like may be added.
[0017]
In the step of evaporating the mixture to dryness and pulverizing it, an evaporator can be used in a laboratory, and a spray dryer can be used industrially. It is preferable that the evaporating temperature is kept at less than 100 ° C., preferably at most 80 ° C. High-temperature drying extremely reduces the foaming property. The drying may be carried out under normal pressure, under pressure, or under reduced pressure.
[0018]
In the step of molding an appropriate green body, for example, compression molding at room temperature, casting and drying as a slurry solution, and filling in a container inert to microwaves are performed. At this time, the lid does not have to be provided (that is, it is not necessary to completely harden the lid). If the green body is in a substantially uniform state, uniformity during foaming can be achieved.
[0019]
Generally, the heating by the microwave heating is preferably performed at about 2.45 GHz. This is based on Japanese domestic law (radio law). It is preferable to use the microwave output per powder weight as a standard. This should be defined by repeated experiments. For example, foaming starts at about 100 g / 1 kW in about 1 minute, and foams converge in 2 to 3 minutes. In this state, it is a very brittle foam.
[0020]
Next, the temperature of the microwave heating body is gradually raised from about 200 ° C. by heating with hot air or the like (for a rough guide, a temperature rising rate of about 100 ° C./10 minutes). The final step is heating at a temperature of glass transition temperature (Tg) + α of polyimide generated by heating for 5 to 60 minutes, preferably about 10 minutes.
By performing the heating and foaming in each of the above steps, the shape becomes irregular, but a foam having uniform elasticity in a foamed state and excellent in restoring force can be obtained.
[0021]
In the above method, the heating of the polyimide precursor in a solid state is preferably performed in two stages, that is, heating for foaming and heating for heat setting (higher molecular weight).
In the above-mentioned method for producing a foamed polyimide, it is preferable that heating for foaming is performed by microwave heating in order to improve heating uniformity.
Heating for heat setting (high molecular weight) is performed by heating at a temperature higher than the glass transition temperature (Tg) of the foamed polyimide, preferably higher than 310 ° C. and lower than 500 ° C. for about 5 to 60 minutes. Is preferred.
[0022]
The foamed polyimide resin mass obtained by the foaming step can have any desired expansion ratio, but preferably has a density of 0.0005 to 0.1 g / cm 3 .
[0023]
In the present invention, the pre-foamed polyimide resin mass is crushed, mixed with a heat-resistant binder, and the mixture is poured into a mold having a predetermined shape, and then pressurized to a predetermined density and fired. By doing so, a foamed polyimide molded body is obtained.
[0024]
The method for crushing the foamed polyimide resin in the above method is not particularly limited, and for example, a crusher for a plastic molded body can be appropriately used.
According to the method described above, it is preferable to obtain a crushed product having a diameter (diameter) of about 1 mm to 50 mm in terms of a sphere as a polyimide resin foamed mass.
[0025]
In the present invention, it is important to mix the above crushed product with a heat resistant binder.
As the above-mentioned heat-resistant binder, polyamic acid is preferable because it is necessary to function as a binder while maintaining the heat resistance of polyimide.
Particularly, as the binder polyamic acid, an aromatic tetracarboxylic acid component, preferably a polyamic acid or an aromatic tetracarboxylic acid component obtained from an asymmetric aromatic tetracarboxylic acid component and an aromatic diamine, and meta-substituted. A polyamic acid which gives a heat-resistant heat-fusible polyimide, such as a polyamic acid obtained from an aromatic diamine, is preferred.
In the above method, the polyamic acid of the binder may be used in the form of a powder of the polyamic acid, or may be used as a solvent solution. When used as a solvent solution of a polyamic acid, the concentration of the polyamic acid is suitably about 1 to 20% by mass.
[0026]
As the aromatic tetracarboxylic acid component, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 3 ′, 4′-biphenyltetracarboxylic dianhydride, 1,2,3 ′, 4′-benzophenonetetracarboxylic dianhydride, 1,2,3 ′, 4′-diphenylethertetracarboxylic dianhydride Anhydrides, 1,2,3 ', 4'-diphenylmethanetetracarboxylic dianhydride and their acids or esters, preferably asymmetric aromatic tetracarboxylic acid components such as 2,3,3', 4'- Biphenyltetracarboxylic dianhydride, 1,2,3 ′, 4′-benzophenonetetracarboxylic dianhydride, 1,2,3 ′, 4′-diphenylethertetracarboxylic dianhydride, 1,2 , 3 ', 4'-diphenylmethanete Rakarubon acid dianhydride and these acids or esters, in particular 2,3,3 ', may be mentioned 4'-biphenyltetracarboxylic dianhydride.
[0027]
The aromatic diamine to be reacted with the aromatic tetracarboxylic acid component is not particularly limited, but is an aromatic diamine having 3 to 4 benzene rings, for example, 1,3-bis (4-aminophenoxybenzene), Examples thereof include 3-bis (4-aminophenoxy) biphenyl, preferably 1,3-bis (4-aminophenoxybenzene). 80% by mole or less of the asymmetric aromatic tetracarboxylic dianhydride may be replaced by a symmetrical aromatic tetracarboxylic acid component, and 80% by weight of the aromatic diamine having 3 to 4 benzene rings. Up to mol% may be replaced by an aromatic diamine having 1-2 benzene rings.
[0028]
In the above method, the amount of the heat-resistant binder used is preferably 2 to 30 parts by mass based on 100 parts by mass of the crushed polyimide resin foam in terms of solid content.
The method of mixing the crushed polyimide resin foam and the heat-resistant binder is not particularly limited. For example, the crushed polyimide resin foam and the heat-resistant binder powder are mixed by a kneader. And a method of spraying a solution of a heat-resistant binder onto a crushed product of a foamed polyimide resin mass.
[0029]
In the present invention, a mixture of a crushed product of a polyimide resin foam and a heat-resistant binder is put into a mold having a predetermined shape, and then pressurized to a predetermined density and fired to obtain a foamed polyimide molded body. be able to.
As the mold, a mold made of a heat-resistant material, for example, a metal, preferably a stainless steel can be used.
[0030]
The pressurization and baking are performed, for example, by putting a crushed product of a polyimide resin foam in which a heat-resistant binder is mixed in a mold into a stainless steel mold provided with a gas vent, and pressing a predetermined size (for example, Height) and fixed the holding lid, and then placed in a heating furnace heated to a temperature of 250 ° C. or higher and the glass transition temperature of the polyimide foam or lower, preferably 300 ° C. or higher and 400 ° C. or lower. It is preferable to carry out by placing for about a minute.
[0031]
The polyimide molded article of the present invention preferably has a heat resistance test at 300 ° C. for 60 minutes with no change in appearance and a mass loss of 1% or less.
The polyimide molded article of the present invention has a density of 0.01 to 0.8 g / cm 3 by selecting molding conditions.
Further, the foamed polyimide molded article of the present invention can be formed into any of sheet, pipe, column, cube, and box by selecting a mold. It has a shape, an inner diameter of 10 to 1000 mm and an outer diameter of 15 to 2000 mm, or a side having a shape of a block consisting of A, B, C, wherein A, B, C are each independently 10 to 10 mm. A foamed polyimide molding having a size of 3000 mm can be obtained.
[0032]
【Example】
The methods for measuring physical properties in Examples and Comparative Examples are shown below.
Glass transition temperature: Measured at a heating rate of 20 ° C./min in a N 2 atmosphere using a DSC (DSC220C, manufactured by Seiko-Electronic Industries).
Expansion ratio: Calculated from true density / apparent density.
As the true density, a value obtained by preparing a polyimide film having the same composition by an ordinary method and using a density gradient tube was used.
The apparent density was obtained by measuring a volume obtained by measuring a cube or a square sheet cut with a vernier caliper, and measuring the mass with a balance, and then calculating the mass / volume.
Tensile strength: A strip-shaped sample of 150 mmL × 25 mmW × 10 mmT was cut out and measured at a tensile speed of 10 mm / min using a Tensilon tensile tester (manufactured by Orientec).
Tensile elongation: Measured with the same sample, measuring instrument and measuring conditions as in the tensile strength measurement test.
Heat resistance test: The appearance and mass change after standing in an oven for 60 minutes were determined.
[0033]
In the following description, each abbreviation means the following compound.
a-BPDA: 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride BTDA: 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride PPD: p-phenylenediamine ODA: 4 4'-Diaminodiphenyl ether TPE-R: 1,3-bis (4-aminophenoxy) benzene DADSi: 1,3-bis (3-aminopropyl) tetramethyldisiloxane DMZ: 1,2-dimethylimidazo- Le [0034]
Example 1
180 mmol of a-BPDA, 70 g of methanol and 2.44 g of DMZ were charged into a 500 ml eggplant-shaped flask, and heated and stirred for 90 minutes while refluxing in a 90 ° C. oil bath to form a homogeneous solution. Next, after cooling this solution to 30 ° C. or less, 189 mmol of PPD, 2 mmol of DADSi, and 30 g of methanol were added to obtain a uniform solution. This solution was concentrated with an evaporator and dried at 60 ° C. under reduced pressure to obtain a solid.
The solid was pulverized and powdered to form a green body using a compression molding machine, and a foam having a foaming ratio of 130 was obtained from the green body using a microwave heating device. . This foam was heated at 450 ° C. for 15 minutes to obtain a polyimide foam.
A chip obtained by crushing this polyimide foam into a size of approximately φ5 mm with a crusher was obtained.
[0035]
A polyamic acid having a viscosity of 9 cp obtained by polymerizing a-BPDA and 1,3-bis (4-aminophenoxy) benzene as a heat-resistant binder at a concentration of 5.5% by mass in dimethylacetamide was added to this chip. Using a solution, 27 g of the heat-resistant binder solution was sprayed onto 15 g of the chip while stirring the chip using a sprayer, and mixed and stirred for about 10 minutes to obtain a mixture of the chip and the heat-resistant binder. Got. A chip of this mixture was put into a stainless steel mold having a height of 250 mm, a width of 150 mm and a length of 200 mm, and was compressed to a height of 200 mm with a holding lid provided with a gas vent, and the holding lid was fixed. The container was placed in an oven and baked at 350 ° C. for 30 minutes. After cooling, the foamed polyimide molded body was taken out of the mold.
This polyimide foam was examined for density, tensile strength, appearance and mass change after standing in a 300 ° C. oven for 60 minutes. The results are summarized in Table 1.
[0036]
Example 2
A foamed polyimide having a foaming ratio of 140 was obtained in the same manner as in Example 1 except that DADE was used as the diamine component. A foamed polyimide molded body was obtained in the same manner as in Example 1 except that this foamed polyimide foam was used.
This polyimide foam was examined for density, tensile strength, appearance and mass change after standing in a 300 ° C. oven for 60 minutes. The results are summarized in Table 1.
[0037]
Example 3
A molded polyimide foam having a density of 0.015 g / cm 3 was obtained in the same manner as in Example 1 except that the expansion ratio was changed.
This polyimide foam was examined for density, tensile strength, appearance and mass change after standing in a 300 ° C. oven for 60 minutes. The results are summarized in Table 1.
[0038]
Example 4
Example 1 was repeated except that the polyamic acid solution obtained in the same manner as in Example 1 was used except that the heat-resistant binder was composed of 80 mol of a-BPDA and 20 mol% of s-BPDA as aromatic tetracarboxylic acid components. Similarly, a foamed polyimide molded body was obtained.
This polyimide foam was examined for density, tensile strength, appearance and mass change after standing in a 300 ° C. oven for 60 minutes. The results are summarized in Table 1.
[0039]
Example 5
A foamed polyimide molded article having the dimensions shown in FIG. 2 was obtained in the same manner as in Example 1 except that the shape of the mold was changed.
This polyimide foam was examined for density, tensile strength, appearance and mass change after standing in a 300 ° C. oven for 60 minutes. The results are summarized in Table 1.
[0040]
Comparative Example 1
A urethane-based binder was used as the heat-resistant binder, the amount of the binder was sprayed in an amount of 10% by mass with respect to the chip, and the density was 0.03 g / cm 3 using the mold described in Example 1. Was molded and then heated with a steam at 100 ° C. to cure the urethane binder to obtain a foamed polyimide molded article made of urethane binder. After drying in a 60 ° C. atmosphere according to a conventional method, evaluation was performed. . The results are summarized in Table 1.
[0041]
[Table 1]
From Table 1, according to Examples 1 to 5, the density was not less than 0.01 g / cm 3 and not more than 0.1 g / cm 3 , and the heat loss test at 300 ° C. for 60 minutes showed no change in appearance and a reduction in mass of 1%. This shows that a polyimide foam molded article having the following heat resistance was obtained.
On the other hand, according to Comparative Example 1 in which a binder having low heat resistance was used, in the heat resistance test described above, the carbonization was partially carbonized, the appearance changed, and the mass loss did not have heat resistance of more than 1%. This shows that a polyimide foam molded article was obtained.
[0043]
【The invention's effect】
According to the present invention, a foamed polyimide molded article having heat resistance and molded into an arbitrary shape can be obtained.
Further, according to the method of the present invention, a foamed polyimide having the above characteristics can be produced by a simple operation.
[Brief description of the drawings]
FIG. 1 is a photograph of a foamed polyimide molding as an example of the present invention.
FIG. 2 shows dimensions of a foamed polyimide molded article obtained in Example 5 which is an example of the present invention.
Claims (14)
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
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| JP2003121373A JP4096798B2 (en) | 2003-04-25 | 2003-04-25 | Foamed polyimide molding and its production method |
| US10/828,772 US20040229969A1 (en) | 2003-04-25 | 2004-04-21 | Foamed polyimide shaped article and process for production of same |
| EP04009467A EP1471106A1 (en) | 2003-04-25 | 2004-04-22 | Foamed polyimide shaped article and process for production of same |
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| JP2003121373A JP4096798B2 (en) | 2003-04-25 | 2003-04-25 | Foamed polyimide molding and its production method |
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| JP2004323715A true JP2004323715A (en) | 2004-11-18 |
| JP4096798B2 JP4096798B2 (en) | 2008-06-04 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007063380A (en) * | 2005-08-30 | 2007-03-15 | Ube Ind Ltd | Method for producing polyimide precursor powder for expansion molding use |
| JP2009242661A (en) * | 2008-03-31 | 2009-10-22 | Ube Ind Ltd | Light-weight polyimide molded body and manufacturing method thereof |
| WO2011074641A1 (en) | 2009-12-16 | 2011-06-23 | 宇部興産株式会社 | Polyimide short fibers and heat-resistant paper comprising same |
| WO2012165294A1 (en) * | 2011-06-01 | 2012-12-06 | 宇部興産株式会社 | Polyimide powder and porous polyimide body using same |
| JP2014530929A (en) * | 2011-10-21 | 2014-11-20 | エボニック レーム ゲゼルシャフト ミット ベシュレンクテル ハフツングＥｖｏｎｉｋ ＲｏｅｈｍＧｍｂＨ | Process for producing poly (meth) acrylimide-based expansion copolymer containing adhesion promoter |
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- 2003-04-25 JP JP2003121373A patent/JP4096798B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007063380A (en) * | 2005-08-30 | 2007-03-15 | Ube Ind Ltd | Method for producing polyimide precursor powder for expansion molding use |
| JP2009242661A (en) * | 2008-03-31 | 2009-10-22 | Ube Ind Ltd | Light-weight polyimide molded body and manufacturing method thereof |
| WO2011074641A1 (en) | 2009-12-16 | 2011-06-23 | 宇部興産株式会社 | Polyimide short fibers and heat-resistant paper comprising same |
| US8709205B2 (en) | 2009-12-16 | 2014-04-29 | Ube Industries, Ltd. | Polyimide short fibers and heat-resistant paper comprising same |
| WO2012165294A1 (en) * | 2011-06-01 | 2012-12-06 | 宇部興産株式会社 | Polyimide powder and porous polyimide body using same |
| EP2716698A1 (en) * | 2011-06-01 | 2014-04-09 | Ube Industries, Ltd. | Polyimide powder and porous polyimide body using same |
| EP2716698A4 (en) * | 2011-06-01 | 2014-12-17 | Ube Industries | Polyimide powder and porous polyimide body using same |
| JPWO2012165294A1 (en) * | 2011-06-01 | 2015-02-23 | 宇部興産株式会社 | Polyimide powder and polyimide porous body using the same |
| JP2014530929A (en) * | 2011-10-21 | 2014-11-20 | エボニック レーム ゲゼルシャフト ミット ベシュレンクテル ハフツングＥｖｏｎｉｋ ＲｏｅｈｍＧｍｂＨ | Process for producing poly (meth) acrylimide-based expansion copolymer containing adhesion promoter |
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