JP3985368B2 - Film formation method - Google Patents

Description

【００１５】
一般式（II）
【化２】

【００１６】
ここで、Ａｒ₁ 、Ａｒ₂ 、Ａｒ₃ にはそれぞれ例えば、
【化３】

等が挙げられ、Ｘ、Ｙは、−Ｏ−，−ＣＨ₂ −，−ＣＯ−，−ＳＯ₂ −，−Ｓ−，−Ｃ（ＣＨ₃ ）₂ −，−Ｃ（ＣＦ₃ ）₂ −等から選択されるが、これらに限定されるわけではない。
【００１７】
更にこれらの芳香環上の水素原子がＲ、Ｒ’あるいはＲ”としてハロゲン基、ニトロ基、Ｃ１〜Ｃ３のアルキル基、Ｃ１〜Ｃ３のアルコキシ基、トリアルキルシリル基、アリール基、オキシアリール基、チオアリール基等の置換基で置換された芳香環が全体の３０％以上、好ましくは５０％以上、更に好ましくは７０％以上であると耐湿性が向上し、吸湿による寸法変化、剛性低下などの特性が改善されるために好ましく、また、アミド基上の水素が他の置換基で置換されていても構わない。
【００１８】
特性面からは上記の芳香環がパラ配向性をもって結合されたものが、全芳香環の５０％以上、好ましくは７０％以上、更に好ましくは７５％以上を占めることが好ましい。ここで言うパラ配向性とは主鎖を構成するアミド結合に結合した芳香核上の二価の結合鎖が互いに平行あるいは同軸である状態を言う。かかる芳香族ポリアミドはフィルムあるいはシート状成形体としたときに薄膜化に好ましい強度、伸度、剛性、耐熱性等の機能を具備する。このようなパラ配向性芳香核の例としては次のようなものがある。
【００１９】
【化４】

【００２０】
かかる芳香族ポリアミドを得る方法には例えば低温溶液重合法、界面重合法、イソシアネートとカルボン酸を反応させる方法、脱水触媒を用い直接縮重合させる方法などがあるが、低温溶液重合法が高重合度のポリマーが得やすいため適している。すなわち、酸クロリドとジアミンから、Ｎ−メチルピロリドン（以下、ＮＭＰという）、ジメチルアセトアミド（以下、ＤＭＡｃという）、ジメチルホルムアミド（以下、ＤＭＦという）などの非プロトン性有機極性溶媒中で重合する。ポリマ溶液は、単量体として酸クロリドとジアミンを使用すると塩化水素が副生するが、これを中和する場合には水酸化カルシウム、炭酸カルシウム、炭酸リチウムなどの無機の中和剤、またエチレンオキサイド、プロピレンオキサイド、アンモニア、トリエチルアミン、トリエタノールアミン、ジエタノールアミンなどの有機の中和剤が使用される。
【００２１】
これらのポリマ溶液はそのまま製膜原液として使用してもよく、あるいはポリマを一度単離してから上記の有機溶媒や、硫酸等の無機溶剤に再溶解して製膜原液を調製してもよい。
【００２２】
また、ポリマーの固有粘度（ポリマ０．５ｇを硫酸中で１００ｍｌの溶液として３０℃で測定した値）は、０．５以上であることが好ましい。
【００２３】
ポリマー溶液には溶解助剤として無機塩例えば塩化カルシウム、塩化マグネシウム、塩化リチウム、硝酸リチウムなどを添加する場合もある。ポリマー溶液中のポリマー濃度は２〜４０wt％程度が好ましい。
【００２４】
また、本発明で言う芳香族ポリイミドとは、重合体の繰り返し単位の中に芳香環とイミド環を１つ以上含むものであり、一般式（ＩＩＩ）および／または一般式（ＩＶ）で示される構造単位で表される。
【００２５】
一般式（ＩＩＩ）
【化５】

【００２６】
一般式（ＩＶ）
【化６】

【００２７】
ここでＡｒ₄ 、Ａｒ₆ は少なくとも１個の芳香環を含み、イミド環を形成する２つのカルボニル基は芳香環上の隣接する炭素原子に結合している。このＡｒ₄ は、芳香族テトラカルボン酸あるいはこの無水物に由来する。代表例としては次の様なものが挙げられる。
【００２８】
【化７】

【００２９】
ここでＺは
−Ｏ−，−ＣＨ₂ −，−ＣＯ−，−ＳＯ₂ −、−Ｓ−，−Ｃ（ＣＨ₃ ）₂ −等から選ばれるが、これに限定されるものではない。
【００３０】
また、Ａｒ₆ は無水カルボン酸あるいはこのハライドに由来する。
【００３１】
Ａｒ₅ 、Ａｒ₇ としては例えば
【化８】

などが挙げられ、Ｘ’、Ｙ’は
−Ｏ−，−ＣＨ₂ −，−ＣＯ−，−ＳＯ₂ −、−Ｓ−，−Ｃ（ＣＨ₃ ）₂ −等から選ばれるが、これに限定されるものではない。更にこれらの芳香環上の水素原子の一部が、ハロゲン基（特に塩素）、ニトロ基、Ｃ1 〜Ｃ3 のアルキル基（特にメチル基）、Ｃ1 〜Ｃ3 のアルコキシ基などの置換基で置換されているものも含み、また、重合体を構成するアミド結合中の水素が他の置換基によって置換されているものも含む。
【００３２】
かかる芳香族ポリイミドの溶液は次のようにして得られる。即ち、原料となるポリアミド酸は、ＮＭＰ、ＤＭＡｃ、ＤＭＦなどの非プロトン性有機極性溶媒中で、テトラカルボン酸二水物と芳香族ジアミンを反応させて調製することができる。それから芳香族ポリイミドは、前記のポリアミド酸を含有する溶液を加熱したり、ピリジンなどのイミド化剤を添加してポリイミドの粉末を得、これを再度溶媒に溶解して調製できる。製膜原液中のポリマ濃度は５〜４０ｗｔ％程度が好ましい。
【００３３】
次に有機高分子体溶液のもう一つの成分である溶媒としては、上記の有機高分子体が溶解するものであれば特に制限はなく、また、混合溶媒であっても溶解助剤などの無機塩が含有されていても構わないが、製膜溶液として調製後に常温下に密閉しておいた時、１週間以上外観上の濁りなどの変化あるいは有機高分子体の析出のみられないものが好ましい。
【００３４】
また、溶液とする手段には特に制限はなく、公知の溶解手段の他上述のように該溶媒中で重合を実施して直接に有機高分子体溶液を得る方法も含まれる。
【００３５】
また、安定に溶液状態を維持できるのであれば該有機高分子体溶液には可溶性の有機物あるいは無機塩が溶解されていても良く、また、溶液溶媒には可溶であるが有機高分子体は単独では溶解しない溶媒が少量混合されていても構わない。また、必要であれば物性を損なわない程度に滑剤、酸化防止剤その他の添加剤等がブレンドされていてもよく、また、有機あるいは無機の粒子などの不溶性成分が分散されていても良い。
【００３６】
次にこれら有機高分子体溶液はエンドレスベルトやドラムなどのキャスト支持体にキャストされる。フィルムあるいはシート状にキャストする手段については従来公知の手段を採用することができ、Ｔ−ダイ、Ｌ−ダイなどを用いる方法が実用的である。
【００３７】
本発明は有機高分子体溶液を支持体上にキャストするにあたり、該支持体とキャストされる有機高分子体溶液膜との間に該有機高分子体及び該溶液に主に用いられた溶媒（この溶媒を以下、溶液溶媒と称する）に対して相溶性を有する溶媒（以下、介在溶媒と称する）を介在溶媒の厚みｔ（μｍ）とキャストされる有機高分子体溶液膜の厚みＴ（μｍ）が０．００１≦ｔ／Ｔ≦０．１、好ましくは０．００１≦ｔ／Ｔ≦０．０１を満たすように介在させることを特徴とする。ｔ／Ｔの関係が０．００１を下回る場合、空気の噛み込みを抑制する効果が小さくキャスト速度が上がらず、０．１を上回る場合、キャストされた有機高分子体溶液が支持体上で滑り、平面性や表面性が悪化する場合がある。ここで言う主に用いられたとは、専ら有機高分子体を溶解させる目的に使用されることを言い、一種以上の混合溶媒であっても良く、各構成成分は単独成分として有機高分子体に対し相溶性を有している。ここで言う相溶性とは該有機高分子体に対して常温において１重量％以上、好ましくは１０重量％以上の溶液を形成しうる溶媒として定義される。
【００３８】
介在溶媒は該有機高分子体に対し相溶性を有している。ここで言う相溶性は該有機高分子体に対して常温において１重量％以上、好ましくは１０重量％以上の溶液を形成しうる溶媒として定義される。
【００３９】
また、介在溶媒は溶液溶媒に対しても相溶性を有している。ここで言う相溶性とは溶液溶媒に対し、１０重量％混合しても完全に混じり合う、つまり混合液とした時液−液界面を形成しない状態で安定化する溶媒として定義する。
【００４０】
また、キャストされた有機高分子体溶液は溶媒の除去により成形体となるため、後処理等を考慮すると介在溶媒は溶液溶媒に主に用いられた溶媒と同一種からなることが好ましく、介在溶媒と溶液溶媒とが実質的に同一であることがさらに好ましい。この時、エントロピー変化を最小にできるので、混合時の発熱などで生じる変質や溶媒の蒸発などの不具合を解消できるという点でも好ましく採用される。 本発明はかかる介在溶媒を採用し、有機高分子体溶液のキャスト時に支持体との間に０．００１≦ｔ／Ｔ≦０．１、好ましくは０．００１≦ｔ／Ｔ≦０．０１を満たすように介在させることに特徴がある。これにより従来の溶液製膜法では得られなかったキャスト速度の高速化がはかられ、また、得られたフィルムの品位例えば表面性や平面性が極めて良好なものとなる。この本発明の優れた効果は、有機高分子体ならびに溶液溶媒との親和性が良好であるために有効かつ強力に介在溶媒の膜が支持体とキャストされた有機高分子体溶液膜との間に形成され、該介在溶媒の膜によって空気がかみこまれるのを防止し、キャスト速度の劇的な向上が図れたものと考えられる。また、介在溶媒は有機高分子体及び溶液溶媒と相溶性を有しているので、支持体界面でのポリマー析出やゲル化も防止されると共に介在溶媒はその後有機高分子体溶液膜に吸収されるために最終製品の表面性や平面性なども良好になるものと考えられる。
【００４１】
次に、本発明に用いた製膜装置をより詳しく説明するために図を用いて説明する。もちろんこれに本発明が制限されるものではない。
【００４２】
本発明に用いた製膜装置は、有機高分子体溶液をダイなどを通じて押し出す押し出し手段と、押し出された有機高分子体溶液を支持するエンドレスベルトあるいはロール状の支持体と、該溶液中の溶媒を除去して成形する手段と、必要に応じて成形体を把持・展長する手段とを具したフィルムあるいはシート状成形体を得る製膜装置において、押し出された有機高分子体溶液と支持体間に該有機高分子体及び該有機高分子体溶液に主に用いられる溶媒に対して相溶性を有する溶媒を介在せしめる手段を有することを要旨とする。
【００４３】
すなわち、図１に示す製膜装置は、有機高分子体溶液を押し出す押し出し手段としてＴダイ１が、押し出された有機高分子体溶液を支持する支持体として、Ｔダイ１に近接してキャストドラム７が設けられている。そして、Ｔダイ１から押し出された有機高分子体溶液膜５とキャストドラム７間に該有機高分子体及び該有機高分子体溶液に主に用いられる溶媒に対して相溶性を有する溶媒を介在せしめる手段、すなわち溶媒付与装置Ｂが、Ｔダイ１の上流側に設けられている。溶媒付与装置Ｂは、その位置調節が可能となるように圧接機構３により可動化されている。
【００４４】
この例においては、更に有機高分子体溶液膜５を支持体７に密着させる手段として密着装置Ａを有する。密着装置Ａは、Ｔダイ１の下流側に設けられたエアナイフノズル６を有し、エアナイフノズル６には公知の手段により空気が送り込まれている。吹き出し圧力は圧力計２及びエアナイフノズル６のスリット幅等で制御される。
【００４５】
溶媒付与装置Ｂは図１に示すようにキャスト支持体に接触して該支持体上に介在溶媒を付与せしめるものでも、図３、４に示すように非接触で付与せしめるものであっても良いが、該支持体との摩擦がなく、キズをつける懸念が少ないことから、非接触で付与せしめる方式を採用することが好ましい。
【００４６】
接触式溶媒付与装置は、図１に示すように、例えば送液ポンプ９や、タンクに空気を送り込んで介在溶媒を押し出す等の介在溶媒の供給手段と、該介在溶媒を供給する介在溶媒供給管４と、該介在溶媒供給管４を通じて供給された介在溶媒を保持し、支持体に介在溶媒を付与する機能を有するスポンジや布、吸収材などの材料からなるロール状、板状あるいは棒状の介在溶媒塗布体８と、必要に応じ上記介在溶媒塗布体８をキャスト支持体に圧接する介在溶媒塗布体支持圧接機構３とから構成される。
【００４７】
これを、図２を例に更に詳しく説明する。ロール状の介在溶媒塗布体８中には介在溶媒供給管４に連結して、介在溶媒を供給する介在溶媒放出管１０が貫通されている。介在溶媒放出管１０の外周には多数の細孔を有しており、介在溶媒塗布体８の介在溶液の保持量が常に一定量となるように送液ポンプ９（図示せず）側で調整されている。また、必要に応じ介在溶媒放出管１０等を支持する形でキャストドラム７への圧力を一定に維持しながら圧接させる介在溶媒塗布体支持圧接機構３が連結されている。
【００４８】
図３は、有機高分子溶液膜５を支持する支持体としてキャストベルト１２を、介在溶媒付与装置Ｂとして非接触式介在溶媒付与装置を用いた例を示す。
【００４９】
すなわち、Ｔダイ１から押し出された有機高分子体溶液５はキャストベルト駆動用ドラム７’にて駆動されるキャストベルト１２上に押し出される。
【００５０】
非接触式溶媒付与装置は、図３のＢで示され、介在溶媒を直接介在溶媒供給管４を通じて、噴霧ノズルや加熱装置、振動膜などからなる気化器または霧化器１３に供給し、気化あるいは霧化を実施し、キャストベルト１２上に介在溶媒を塗布する。介在溶媒を気化せしめたときにはキャストベルト１２の温度を小さくして、該ベルト上に凝結させることもできる。
【００５１】
全体的な付与量あるいは長手方向の付与量の均一性の調整は介在溶媒の供給手段、すなわち送液ポンプ９（図示せず）側で調整され、また、幅方向の付与量の調整は気化器あるいは霧化器１３において幅方向に対する配設間隔や各器毎の介在溶媒の背圧や供給量を制御すること等で達成することができる。また、該非接触式溶媒付与装置には、図中にしめすように支持体に付着しなかった過剰な気化あるいは霧化された介在溶媒が系外に漏れ出ないように気化器あるいは霧化器１３を覆うようにチャンバー１４を設け、吸気ブロワーなどの吸引手段に接続された排気管１５を配設して排気する手段を設けることができる。また、凝結あるいは付着した介在溶媒がキャスト支持体上に滴下しないようチャンバー１４、導入管４、排気管１５などを加熱したり、チャンバー１４の辺縁部などに樋などの回収機構を設けることができる。
【００５２】
また、この例においては、更に有機高分子体溶液膜５をキャストベルト１２に密着させる手段として密着装置Ａを有している。密着装置Ａは、Ｔダイ１の上流側に設けられた吸引ノズル１１を有し、該吸引ノズル１１は吸引ブロワーなど公知の手段により空気の吸引が行われる。幅方向の分布含め、吸引圧力は圧力計２及び吸引ノズル１１の開口部の構成等で制御される。
【００５３】
図４は、有機高分子溶液膜５を支持する支持体としてキャストドラム７を、介在溶媒付与装置Ｂとして図３とは別の態様の非接触式介在溶媒付与装置を用いた例である。
【００５４】
この例では、直接に気化あるいは霧化して介在溶媒を付与するのではなく、別に設けられた気化室あるいは霧化室１８中に噴霧ノズルや加熱装置あるいは振動膜などを利用した気化器あるいは霧化器１３を設けて該室内にて介在溶媒の気化あるいは霧化を行う。そして、必要に応じ送気管１６から気化室あるいは霧化室内に搬送気体を送り込み、導入管１７からチャンバー１４内に設けられた放出器１９に導入し、キャストドラム７上へ導いて付着させている。
【００５５】
この例においても、気化した介在溶媒を用いるときにはキャスト支持体温度を小さくし、キャスト支持体上で凝結させることは行われて良い。また、支持体に付着しなかった過剰な気化あるいは霧化された介在溶媒が系外に漏れ出ないように放出器１９を覆うようにチャンバー１４を設け、吸気ブロワーなどの吸引手段に接続された排気管１５を配設して排気する手段を設けることができる。また、凝結あるいは付着した介在溶媒がキャスト支持体上に滴下しないよう気化あるいは霧化室１８、チャンバー１４、導入管１７、排気管１５などを加熱したり、チャンバー１４の辺縁部などに樋などの回収機構を設けることができる。
【００５６】
また図５、６は本発明の別の態様を示している。すなわち、図５、６に示す製膜装置は、有機高分子体溶液を押し出す押し出し手段としてＴダイ１が、押し出された有機高分子体溶液を支持する支持体として、Ｔダイ１に近接してキャストドラム７が設けられている。そして、これらの例においては押し出された有機高分子体薄膜側に介在溶媒膜が形成された後、キャストドラム７上に流延されるものである。
【００５７】
図５はＴダイ１の断面を示しているが、該ＴダイにはＴダイ１から押し出された有機高分子体溶液膜５とキャストドラム７間に該有機高分子体及び該有機高分子体溶液に主に用いられる溶媒に対して相溶性を有する溶媒を介在せしめる手段として、Ｔダイ下部に介在溶媒供給管４に接続した毛細管や多孔質体などを利用した介在溶媒供給細管２０が設けられており、有機高分子体溶液膜５を押し出した直後に介在溶媒が該溶液に付与される。介在溶媒の付与量は溶媒供給管４のもう一端に接続された送液ポンプ９（図示せず）側で調整され、また、幅方向の付与量の調整は介在溶媒供給細管２０の構成を適宜調整すること等で達成することができる。
【００５８】
図６もＴダイ１の断面を示しているが、この場合は有機高分子体及び該有機高分子体溶液に主に用いられる溶媒に対して相溶性を有する溶媒を介在せしめる手段として、Ｔダイ中に介在溶媒供給管４、介在溶媒供給細管２０’を導入し、介在溶媒を有機高分子体溶液に積層してＴダイから共に吐出を行う。介在溶媒の付与量は溶媒供給管４のもう一端に接続された送液ポンプ９（図示せず）側で調整され、また、幅方向の付与量の調整はＴダイ中における供給管の幅や構成を適宜調整すること等で達成することができる。
【００５９】
もちろん高分子溶液の密着性を上げるために図５や図６に示した系においても図１や図２で説明した密着装置が併用できる。
【００６０】
図１〜４に示すように本発明においては、高分子体溶液膜に力を及ぼして支持体に密着させる手段を併用することは極めて好ましい。かかる手段としては先述した吸引ノズルやエアナイフ等のキャストされた有機高分子体溶液膜に対して上流側に空気を吸引する手段や下流側に空気等の作動流体を吹き当てる手段、静電気力や磁力などの間接力を及ぼす手段などの公知の手段が採用し得、取り付け位置の微調整機構を有していることが好ましい。もちろん前記溶媒付与装置とは任意に組み合わせて良い。驚くべきことに本発明と組み合わせて用いることによって、これら手段が従来安定化に必要としていた吹き出し圧力や吸引圧力などは激減する。その結果、従来これらの安定化手法が達し得なかった速度においても低負荷での運転が可能となり、本発明はこの作用と相まって好ましく更に一段の高速化がはかられる。また、空気流れを利用した密着手段の場合、必要圧力の低下で圧力変動も抑制され、薄ものの製膜においても有利に作用する。
【００６１】
なお、図５や図６で示した態様はキャスト支持体を予め加温する必要やその他処理を行う時などに好ましく採用される。
【００６２】
また、介在溶媒はその付与される有効面における付与量のバラツキを３０％以下、好ましくは２０％以下、更に好ましくは１０％以下とすることが好ましい。３０％を越えると特に溶媒の除去に加熱蒸発を採用する製膜手段においては乾燥斑を発生して、得られたフィルムあるいはシート状成形体の物性が不均一なものとなる懸念や平面性が悪化する懸念がある。ここで言う有効面とは実際にキャストされる面として定義され、付与量のバラツキは長手方向あるいは幅方向に単位面積当たりの付与量を１０点測定し、その平均値に対する最大の乖離割合として定義する。付与するに当たっては図１の介在溶媒塗布体支持圧接装置３において幅方向に接圧を調整できる機構を用いたり、図３の供給管やの気化器あるいは霧化器１３や図４の放出器１９において適切に分配器を用いたり、供給孔や発生器などの供給要素の配置を適正化したり、チャンバー１４内に仕切り板を設けることなどで達成することができる。
【００６３】
また、Ｔ−ダイなどを用いて有機高分子体溶液をスリットから押し出す場合、押し出し口とキャスト支持体間との距離は１０ｍｍ以下、好ましくは５ｍｍ以下、更に好ましくは３ｍｍ以下とすることが好ましい。１０ｍｍを越えるときはたとえ介在溶媒を用いたとしても高速化のメリットは少なく、また、押し出された有機高分子体溶液膜の着地線が振れやすく、厚み斑の原因となる恐れがある。また、ネックインの発生で両端の厚みが増え、単位面積当たり溶媒除去量が大きくなって、支持体からの剥離がうまくいかなかったり、得られたフィルムあるいはシート状成形体の物性が不均一なものとなって好ましくない。
【００６４】
本発明で得られるフィルムあるいはシート状成形体の厚みに特に制限はないが、先述のように従来の技術は特に薄ものの成形において技術的に制限が大きかったので、本発明はフィルムあるいはシート状成形体の最終厚みとして、１０μｍ以下、好ましくは７μｍ以下、更に好ましくは５μｍ以下、特に好ましくは４μｍ以下のものを得るに当たって極めて好ましく採用される。
【００６５】
特に本発明は更に、フィルムあるいはシート状成形体の表面性や平面性にも優れるため、ますます高容量化が要求され、またかかる要求にも厳しい磁気記録媒体用ベース材や小型軽量化の進むフレキシブルプリント基板やＴＡＢキャリアテープ、太陽電池基板などの電気機器用絶縁性配線部材、コンデンサーあるいは感熱記録用転写材のベース材などに好ましく採用される。
【００６６】
特に本発明から得られるフィルムあるいはシート状成形体は表面性に優れるので、光触針式３次元表面粗さ計で測定されるカットオフ値０．０８ｍｍにおける測定面積０．００２ｍｍ²での３次元表面粗さＳＲａ１と測定面積１．０ｍｍ²での３次元表面粗さＳＲａ２が好ましく下式のような関係を充たす。
【００６７】
【数１】

【００６８】
ＳＲａ２／ＳＲａ１は好ましくは３．５以下、更に好ましくは３．０以下である。ＳＲａ２／ＳＲａ１が４．５を越えると基材表面には凹凸上のうねりが著しく、製品としての使用に制限が多い。
【００６９】
また、ＳＲａ２／ＳＲａ１は好ましくは０．９以上、更に１．２以上であることがより好ましい。ＳＲａ２／ＳＲａ１が０．８未満であると加工上の問題を発生する懸念があり、最終製品の摩擦耐久性に悪影響が出る可能性がある。
【００７０】
更に本発明により得られるフィルムあるいはシート状成形体は、２０℃、相対湿度６０％における少なくとも一方向の引張りヤング率が、７．８４ＧＰａであることが好ましい。より好ましくは８．８２ＧＰａ以上、更に好ましくは９．８ＧＰａ以上である。一般にヤング率は分子構造と製膜時の延伸性により支配され、先述のパラ配向性芳香族ポリアミドは高ヤング率の材料として好ましく採用される。通常上限は３５ＧＰａ程度であり、これ以上の値のフィルムはもろかったりあるいは裂けやすいものとなって、工業的価値は低い。使用あるいは加工時のテンションに耐えることができるので特に薄膜の成形体に有利である。
【００７１】
また、本発明はもちろん単層のフィルムあるいはシート状成形体の成形でも用いられるが、積層成形体の成形にも好ましく用いられる。積層時の各層を構成する成分は同じ種類であっても異なるものであっても良い。また、各層を構成する少なくとも一層に本発明の目的を損なわない粒子などの副資材を含有していてもよく、これら副資材の種類、含有量、粒径などは同じであっても異なるものであっても良い。
【００７２】
上記手段を経てキャストされた有機高分子体溶液膜はいわゆる溶液製膜法によりフィルムあるいはシート状成形体に加工される。溶液製膜法には乾湿式法、乾式法、湿式法などがありいづれの方法で製膜されても差し支えないが、ここでは乾湿式法を例にとって説明する。
【００７３】
乾湿式法で製膜する場合は、例えば特開昭５４−１０５１９７号公報などに開示される従来公知の方法が用いられる。すなわち、キャスト支持体上にキャストした有機高分子体溶液の薄膜層から溶媒を蒸発させ該薄膜が自己保持性をもつまで乾燥する。乾燥条件は室温〜２２０℃、６０分以内の範囲であり、好ましくは室温〜２００℃の範囲である。乾式工程を終えたフィルムは支持体から剥離されて湿式法と同様の浴中で抽出媒によって脱塩、脱溶媒などが行なわれる湿式工程に導入され、加えて延伸、乾燥、熱処理が行なわれる。
【００７４】
以上のように形成されるフィルムあるいはシート状成形体はその製膜工程中で、テンター中クリップで把持しながら展長したりあるいはロールの周速差を利用するなど従来公知の方法で延伸が行なわれることが好ましいが、延伸倍率は面倍率で０．８〜８．０（面倍率とは延伸後のフィルム面積を延伸前のフィルムの面積で除した値で定義する。１以下はリラックスを意味する。）の範囲内にあることが好ましく、より好ましくは１．１〜５．０である。また延伸あるいは熱処理後のフィルムを徐冷する事が有効であり、５０℃／秒以下の速度で冷却する事が有効である。
【００７５】
なお本発明で得られるフィルムあるいはシート状成形体は、積層されていてもよいが、例えば２層の場合には、有機高分子体溶液を二分し、各々に必要な副資材を添加した後積層する等の方法が用いられる。さらに３層以上の場合も同様である。これら積層の方法としては、周知の方法たとえば、口金内での積層、複合管での積層や、一旦１層を形成しておいてその上に他の層を形成する方法などが採用できる。
【００７６】
［物性の測定方法ならびに効果の評価方法］
本発明の特性値の測定方法ならびに効果の評価方法は次の通りである。
【００７７】
Ａ．ヤング率、伸度
オリエンテック社製テンシロンを用い、試幅１０ｍｍ、試長５０ｍｍ、引張速度３００ｍｍ／分で実施した。なお、測定に当たり試料は２０℃、相対湿度６０％雰囲気下に２４時間以上置き、また該条件において測定を行った。
【００７８】
Ｂ．表面性
真空蒸着機にてフィルム表面をアルミ蒸着し、蒸着面を微分干渉顕微鏡を用いて観察し、実用上の問題となる欠点の有無を調べた。欠点があれば×印、無ければ○印として示した。
【００７９】
Ｃ．厚み斑
電子線マイクロ厚み計を使用し、フィルムの長手方向に連続的に１０ｍの長さを測定し、その最大値と最小値の差を平均厚みで除した値に１００を乗じて求めた（単位：％）。なお、厚み斑は１０％未満を良好として○印で示し、５％以下を最良として◎印で示し、１０％以上を不良として×印で示した。
【００８０】
Ｄ．平面性評価指標
２５℃、相対湿度６０％の環境下で５０ｃｍ×５０ｃｍのフィルムを厚手のフェルト地あるいは不織布（本実施例では東レ（株）社製”エクセーヌ”を用いた。）を貼着した平板上にのせ、ブラシにて広げていく。１５分間静置後、該エクセーヌ上に接触せずに膨らんでいる部分をマーキングし、その面積を求める。そして、該非接触部分の面積をフィルムの総面積で除した値に１００を乗じて求め（単位：％）、１０％未満を良好として○印で示し、５％以下を最良として◎印で示し、１０％以上を不良として×印で示した。
【００８１】
Ｅ．キャスト安定性
有機高分子体をステンレスベルト上に流延したとき、問題がない場合を○印で示し、周期的もしくは断続的に有機高分子体膜に破れが発生した場合を×印で示した。
【００８２】
Ｆ．ＳＲａ２／ＳＲａ１
先に示した方法で測定を行い、０．８≦ＳＲａ２／ＳＲａ１≦４．５を満たすものを良好とし○印で示し、それ以外のものを不良として×印で示した。
【００８３】
【実施例】
以下具体的に実施例に基づき本発明を説明するが、本発明はかかる記載に限定されるものではない。
【００８４】
有機高分子体溶液として、次のものを用いた。平均一次粒径１６ｎｍのシリカ粒子をポリマーあたり０．３ｗｔ％分散したＮＭＰに芳香族ジアミン成分として８０モル％に相当する２−クロルパラフェニレンジアミンと、２０モル％に相当する４、４’−ジアミノジフェニルエ−テルとを溶解させ、これに酸クロリド成分として１００モル％に相当する２−クロルテレフタル酸クロリドを添加し、２時間撹拌して重合を完了した。次いで発生した塩化水素を水酸化リチウムを用い４分の１ずつ添加して中和を行い、ポリマ濃度１０重量％の芳香族ポリアミド溶液を得た。
【００８５】
実施例１
有機高分子体溶液の押し出し手段としてキャスト支持体から２ｍｍ上方に配されてギヤポンプにつながった幅４００ｍｍのＴダイ、キャスト支持体として鏡面状に磨かれたステンレスベルトとベルト駆動のためのキャストロールとからなる支持体、密着手段としてＴダイ上流側にスリットクリアランス１．５ｍｍの吸引ノズルを配し、ついで介在溶媒を付与する手段として吸引ノズル上流側に、溶媒（ＮＭＰ）供給タンク、供給ポンプに連結したノズル式噴霧器とブロワー及びフィルターを経た搬送用空気導入口と霧化体の排出口を装備する霧化室を経て吸引ノズル上流側に設けられたチャンバー内に接続された（凝結体のキャストベルト上への落下防止のため辺縁部に樋の設けられた霧化体の排出口はキャストベルトから２ｍｍ上に設けられている。）間接式供給手段を用い、上記調製した芳香族ポリアミド溶液をホッパーからギヤポンプ、２μｍカットのフィルタ−を通じて、Ｔダイから６５℃のステンレスベルト上に膜厚６０μｍで流延した。この時、キャストベルト上へのＮＭＰの付与量は０．５μｍ±０．０５μｍ（本実施例に示す誤差範囲は先述の有効面における単位面積あたりの付与量測定法に基づく。）であった。また、吸引ノズル内の圧力は−５０ｍｍＡｑであった。
【００８６】
次いでＮＭＰの付与量を０．５μｍ±０．０５μｍに保ちながら最終フィルム厚みが一定となるよう吐出量とキャストベルトの速度を調整しつつ徐々に速度を上げていったところ、４５ｍ／分のキャスト速度でも有機高分子体溶液膜と支持体間に空気を噛み込むこともなくキャストは極めて安定して実施することができた。
【００８７】
次にキャストベルトに保持したまま乾燥機中で１９０℃の熱風で１．５分間加熱して溶媒を蒸発させ、自己保持性を得たフィルムをベルトから連続的に剥離した。次に加温した水槽内へフィルムを導入して残存溶媒と中和で生じた無機塩の水抽出を行ない、テンタ−で水分の乾燥と熱処理を行なって厚さ３．７μｍの芳香族ポリアミドフィルムを得た。水槽内でロール周速度を変えてフィルム長手方向に１．２５倍、２８０℃、１．５分間のテンター内でクリップで把持しつつ乾燥と延伸を行ない幅方向に１．３倍延伸した。ついで、定長下に２９０℃、３０秒間熱処理を行なった後、２０℃／秒の速度で徐冷した。
【００８８】
この基材フィルムのＳＲａ２／ＳＲａ１は１．３５、ヤング率は長手方向、幅方向それぞれ１３ＧＰａ、１３ＧＰａ、伸度４０％であった。
また、表面性においては全く問題が無く、厚み斑は４％、平面性評価指標は４％であり、実用上極めて優れたものであった。
【００８９】
実施例２〜４
ステンレスベルト上にキャストしたポリマー膜厚を１０，３０，１２０μｍ、ＮＭＰの付与量を０．０８μｍ±０．００８μｍ，０．２５μｍ±０．０２５μｍ，１．０μｍ±０．１μｍとした以外実施例１と同様の方法でキャストベルト上にキャストを行った。フィルムの評価結果は表１に示す。
【００９０】
参考例１
吸引ノズル内圧力を０ｍｍＡｑとした他は実施例１と同様の方法でキャストベルト上にキャストを行った。ＮＭＰの付与量を０．５μｍ±０．０５μｍに保ちながら最終フィルム厚みが一定となるよう吐出量とキャストベルトの速度を調整しつつ徐々に速度を上げていったところ、１５ｍ／分のキャスト速度でも有機高分子体溶液膜と支持体間に空気を噛み込むこともなくキャストは極めて安定して実施することができた。次に、実施例１と同様の条件となるよう条件調整して厚さ３．７μｍの芳香族ポリアミドフィルムを得た。この基材フィルムのＳＲａ２／ＳＲａ１は１．３０、ヤング率は長手方向、幅方向それぞれ１３ＧＰａ、１３ＧＰａ、伸度４０％であった。また、このフィルムの表面性においては全く問題が無く、厚み斑は７％、平面性評価指標は６％であった。
【００９１】
実施例６
介在溶媒の供給手段として、介在溶媒の供給機構とキャストベルトへの押圧機構を具備したスポンジ製ロールを配した以外は実施例１と同様の方法と条件で調製した芳香族ポリアミド溶液をホッパーからギヤポンプ、２μｍカットのフィルタ−を通じて、Ｔダイから６５℃のステンレスベルト上に流延した。この時、スポンジロールからキャストベルト上にＮＭＰを４μｍ±０．３μｍ（本実施例に示す誤差範囲は先述の有効面における単位面積あたりの付与量測定法に基づく。）となるよう付与した。
【００９２】
次いでＮＭＰの付与量を４μｍ±０．３μｍに保ちながら最終フィルム厚みが一定となるよう吐出量とキャストベルトの速度を調整しつつ徐々に速度を上げていったところ、４５ｍ／分のキャスト速度でも有機高分子体溶液膜と支持体間に空気を噛み込むこともなくキャストは極めて安定して実施することができた。 以下実施例１と同様の条件となるよう条件調整して厚さ３．６μｍの芳香族ポリアミドフィルムを得た。
【００９３】
この基材フィルムのＳＲａ２／ＳＲａ１は１．５、ヤング率は長手方向、幅方向それぞれ１３ＧＰａ、１３ＧＰａ、伸度４０％であった。
また、このフィルムの表面性、平面性共に実施例１のフィルムに遜色のないものであった。
【００９４】
比較例１
介在溶媒の供給機構を撤去し、キャストベルト上への介在溶媒の付与を行わなかった他は実施例１と全く同じ装置系を用いた。
最終フィルム厚みが一定となるよう吐出量とキャストベルトの速度を調整しつつ徐々に速度を上げていったところ、吸引ノズル内圧力が−５０ｍｍＡｑの時においては、１３ｍ／分で空気の噛み込みを生じ製膜できなくなった。次に吸引ノズル内の圧力を高めながら最終フィルム厚みが一定となるよう吐出量とキャストベルトの速度を調整して速度を上げていったが、−１２０ｍｍＡｑにおいても空気の噛み込みは２０ｍ／分から生じ、これ以上吸引ノズル内圧力を下げると吐出される有機高分子体溶液膜の振れが大きくなり、無視できない厚み斑の発生が認められるようになった。
上記の１３ｍ／分でキャストしたものについて、以下実施例１と同様の条件となるよう条件調整して厚さ３．６μｍの芳香族ポリアミドフィルムを得た。
【００９５】
この基材フィルムのＳＲａ２／ＳＲａ１は１．８、ヤング率は長手方向、幅方向それぞれ１３ＧＰａ、１３ＧＰａ、伸度４１％であった。
また、フィルム表面性は実用上問題がないものの厚み斑は１３％、平面性評価指標は１２％であり実用上満足のゆくものではなかった。
【００９６】
比較例２
比較例１において、更に吸引ノズル内圧力を０にしてキャストを実施したが、７ｍ／分で空気の噛み込みを生じた。
【００９７】
比較例３〜６
ステンレスベルト上にキャストしたポリマー膜厚を１０，３０，６０，１２０μｍＮＭＰの付与量を３．３μｍ±０．３３μｍ，１０μｍ±１μｍ，２０μｍ±２μｍ，４０μｍ±６μｍとした以外実施例１と同様の方法でキャストベルト上にキャストを行った。製膜が可能だったフィルムの評価結果は表１に示す。
【００９８】
比較例３〜６についてキャスト開始直後からネックインが発生しフィルムエッジ部に厚み斑の発生が認められる。
【００９９】
次に吸引ノズル内の圧力を高めつつ、ＮＭＰの付与量を一定に保ち、最終フィルム厚みが一定となるよう吐出量とキャストベルトの速度を調整して速度を上げていったが、比較例３では吸引開始当初から、比較例４では吸引ノズル内圧力が−１０ｍｍＡｑを下回る辺りから、比較例５では吸引ノズル内圧力が−３０ｍｍＡｑを下回る辺りから有機高分子体溶液膜の振れが大きくなり、ともに−１５，−４０，−１００ｍｍＡｑより吸引ノズル内圧力を下げると吐出される有機高分子体溶液膜の振れの影響により無視できない厚み斑の発生が認められるようになった。比較例６のフィルムの評価結果は表１に示す。
【０１００】
【表１】

【０１０１】
【発明の効果】
本発明は上記の構成とすることにより、これまで困難であった溶液製膜における高速製膜と言う課題において、特に薄膜であっても高速度での製膜が可能となり、また、特に本発明は更に、得られるフィルムあるいはシート状成形体の表面性や平面性にも優れるものとできる。
【０１０２】
このようにして得られたフィルムあるいはシート状成形体は光学部材、光記録媒体、磁気記録媒体、電気機器用絶縁性配線部材、コンデンサー、被覆材、製版材料などの印刷部材、写真フィルムなど各種用途に好適に用いることができる。
【図面の簡単な説明】
【図１】第１図は本発明の一態様を示す説明図である。
【図２】第２図は第１図における接触式溶媒付与装置のキャスト支持体接触部分の拡大説明図である。
【図３】第３図は本発明の一態様を示す説明図である。
【図４】第４図は本発明の一態様を示す説明図である。
【図５】第５図はＴダイ部分の断面を表す説明図である。
【図６】第６図はＴダイ部分の断面を表す説明図である。
【符号の説明】
Ａ：密着装置
Ｂ：溶媒付与装置
１：Ｔダイ
２：圧力計
３：介在溶媒塗布体支持圧接機構
４：介在溶媒供給管
５：有機高分子体溶液膜
６：エアナイフノズル
７：キャストドラム
７’：キャストベルト駆動用ドラム
８：介在溶媒塗布体
９：送液ポンプ
１０：介在溶媒放出管
１１：吸引ノズル
１２：キャストベルト
１３：気化器または霧化器
１４：チャンバー
１５：排気管
１６：送気管
１７：導入管
１８：気化室または霧化室
１９：放出器
２０，２０'：介在溶媒供給細管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a film formation method used for solution film formation of an organic polymer such as polycarbonate, aromatic polyamide, and aromatic polyimide.
[0002]
[Prior art]
For example, as means for bringing a melt or solution film extruded from a T-die into close contact with a support, methods using an air knife are disclosed in Japanese Patent Laid-Open Nos. 61-121923 and 59-68681, and an electrostatic field. A method of using this is known in Japanese Patent Publication No. 50-8743, Japanese Patent Laid-Open No. 59-138416, and the like.
[0003]
A method of disposing a slit-like suction nozzle between a molten film or a solution film and a support is known from JP-A-2-52721.
[0004]
However, the method using an air knife is suitable for forming a thick or extremely high-viscosity film. However, a high dynamic pressure is required to improve the adhesion, and at this time, the film is not formed due to the disturbance of the wind pressure. Not stable. This tendency is greatly affected by a solution film having a low viscosity and a decrease in the film thickness. In addition, the method using an electrostatic field is not preferable because of the risk of ignition because an organic solvent is often used in solution casting, and is difficult to apply in principle unless the object to be cast is charged. .
[0005]
Even with a method using a slit-like suction nozzle, a large air flow is required to obtain a high dynamic pressure or static pressure as in the case of the air knife method described above, and the stronger the suction, the more affected by pressure fluctuations. Film formation is not stable.
[0006]
The above problems in these means are particularly noticeable in thin film formation that is easily affected by external force. When the speed is increased, air is caught between the molten film or the solution film and the cast support, and film formation cannot be performed. Had a problem to say.
[0007]
On the other hand, as a method for forming a molten film, a method of forming a liquid film on a drum and casting it is known from Japanese Patent Laid-Open Nos. 64-53820, 1-320130, and 2-219610. It has been. However, the liquid film is inherently foreign with respect to the melted polyester or polyamide, and the high-temperature molten film is rapidly and non-uniformly cooled, or the liquid film-forming substance is vaporized, resulting in liquid on the film surface. Since deformation and roughness due to the film occur, it is particularly desired to reduce the thickness as described later, and it cannot be applied to applications that require a precisely controlled surface.
[0008]
The method using an air knife, a suction nozzle, an electrostatic field, etc. is intended to stabilize the cast by bringing the extruded melt or solution film into close contact with the support, but there is a limit, while further improving productivity. There is a need to speed up casting. On the other hand, recording media such as magnetic tape have been downsized, and due to the demand for longer recording time, a thinner film has been demanded and the base material is highly controlled to improve electromagnetic conversion characteristics. Therefore, the surface property or flatness is required. Conventionally, polyethylene terephthalate has been used for such applications, but materials such as aromatic polyamide or aromatic polyimide having higher rigidity have been studied. However, aromatic polyamide and aromatic polyimide having high rigidity can be obtained only by solution casting, and it has been difficult to form a thin film at a high speed by the above-described means.
In addition, polycarbonate and polymethacrylic acid resins, which have high needs for optical member applications, have similar problems.
[0009]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, and in the production of a film or a sheet-like molded product from an organic polymer solution, it is possible to form a film at a higher speed that could not be achieved by conventional cast stabilization means. An object of the present invention is to provide a film-forming method that can stably form a film even if it is thin, and also has good surface properties and flatness of the obtained film or sheet-like molded product.
[0010]
[Means for Solving the Problems]
  That is, the present inventionOf aromatic polyamide and / or aromatic polyimideIn a method of casting a solution on a support and removing a solvent in the solution to obtain a film or sheet-like molded article,While casting using means for bringing the solution into close contact with the support,Cast with the supportThe solutionBetween liquid filmTheSolvents mainly used in the solutionSame kind ofCasting with a solvent interposed such that a liquid film thickness t (μm) and a cast polymer thickness T (μm) satisfy 0.001 ≦ t / T ≦ 0.1 at the time of casting. Is the method.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The organic polymer used in the present invention is not particularly limited as long as it can be dissolved in one or more appropriate organic or inorganic solvents and the solution can be used for film formation. Examples of such organic polymer materials include polycarbonate, polyurethane, polyvinyl alcohol resin, polyacrylonitrile, polyamide resin such as aromatic polyamide, aromatic polyimide, polyesteramide, polyamideimide, polyacrylic acid resin, polymethacrylic acid Examples thereof include resins, polyester resins, cellulosic polymers, silicone resins, and fluororesins.
[0012]
The present invention is preferably employed in an organic polymer that can substantially only form a solution film and has a melting point of approximately 300 ° C. or higher or a decomposition point lower than the melting point. The decomposition point mentioned here means a temperature at which the weight loss is 5% in thermogravimetric analysis in an air stream. In particular, the present invention can be thinned and does not adversely affect the surface properties, etc., so it is suitable for film formation of a resin having such a strong demand, has appropriate flexibility for thinning, and has a Young's modulus and the like. It is particularly preferably employed in the production of an aromatic polyamide or aromatic polyimide film that requires mechanical properties.
[0013]
The aromatic polyamide referred to in the present invention is composed of 50 mol% or more, preferably 70 mol% or more of repeating units represented by the following general formula (I) and / or general formula (II).
[0014]
Formula (I)
[Chemical 1]

[0015]
Formula (II)
[Chemical 2]

[0016]
Where Ar₁ , Ar₂ , Ar_Three For example,
[Chemical 3]

X, Y is -O-, -CH₂ -, -CO-, -SO₂ -, -S-, -C (CH_Three )₂ -, -C (CF_Three )₂ -Selected from, but not limited to.
[0017]
Furthermore, a hydrogen atom on these aromatic rings is R, R ′ or R ″ as a halogen group, nitro group, C1-C3 alkyl group, C1-C3 alkoxy group, trialkylsilyl group, aryl group, oxyaryl group, When the aromatic ring substituted with a substituent such as a thioaryl group is 30% or more of the whole, preferably 50% or more, more preferably 70% or more, the moisture resistance is improved, and the characteristics such as dimensional change and rigidity reduction due to moisture absorption are improved. Is preferable, and hydrogen on the amide group may be substituted with other substituents.
[0018]
From the viewpoint of characteristics, it is preferable that the above aromatic rings bonded with para-orientation occupy 50% or more, preferably 70% or more, more preferably 75% or more of the total aromatic rings. The term “para-orientation” as used herein refers to a state in which divalent bonding chains on the aromatic nucleus bonded to the amide bond constituting the main chain are parallel or coaxial with each other. Such an aromatic polyamide has functions such as strength, elongation, rigidity, heat resistance and the like preferable for thinning when formed into a film or a sheet-like molded product. Examples of such para-oriented aromatic nuclei are as follows.
[0019]
[Formula 4]

[0020]
Methods for obtaining such aromatic polyamides include, for example, a low temperature solution polymerization method, an interfacial polymerization method, a method of reacting isocyanate and carboxylic acid, and a method of direct condensation polymerization using a dehydration catalyst. It is suitable because it is easy to obtain a polymer. That is, polymerization is performed from an acid chloride and a diamine in an aprotic organic polar solvent such as N-methylpyrrolidone (hereinafter referred to as NMP), dimethylacetamide (hereinafter referred to as DMAc), dimethylformamide (hereinafter referred to as DMF). When acid chloride and diamine are used as monomers in the polymer solution, hydrogen chloride is by-produced. To neutralize this, inorganic neutralizers such as calcium hydroxide, calcium carbonate, lithium carbonate, and ethylene Organic neutralizers such as oxide, propylene oxide, ammonia, triethylamine, triethanolamine, diethanolamine are used.
[0021]
These polymer solutions may be used as a film-forming stock solution as they are, or a film-forming stock solution may be prepared by isolating the polymer once and then re-dissolving it in an organic solvent or an inorganic solvent such as sulfuric acid.
[0022]
The intrinsic viscosity of the polymer (value measured at 30 ° C. in a 100 ml solution of 0.5 g of polymer in sulfuric acid) is preferably 0.5 or more.
[0023]
An inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, or lithium nitrate may be added to the polymer solution as a dissolution aid. The polymer concentration in the polymer solution is preferably about 2 to 40 wt%.
[0024]
The aromatic polyimide referred to in the present invention includes one or more aromatic rings and imide rings in the repeating unit of the polymer, and is represented by the general formula (III) and / or the general formula (IV). Expressed in structural units.
[0025]
Formula (III)
[Chemical formula 5]

[0026]
Formula (IV)
[Chemical 6]

[0027]
Where Ar_Four , Ar₆ Contains at least one aromatic ring, and the two carbonyl groups forming the imide ring are bonded to adjacent carbon atoms on the aromatic ring. This Ar_Four Is derived from aromatic tetracarboxylic acid or its anhydride. Typical examples include the following.
[0028]
[Chemical 7]

[0029]
Where Z is
-O-, -CH₂-, -CO-, -SO₂-, -S-, -C (CH_Three)₂-It is chosen from-etc. However, it is not limited to this.
[0030]
Ar₆ Is derived from carboxylic anhydride or this halide.
[0031]
Ar_Five , Ar₇ For example,
[Chemical 8]

X 'and Y' are
-O-, -CH₂-, -CO-, -SO₂-, -S-, -C (CH_Three)₂-It is chosen from-etc. However, it is not limited to this. Furthermore, some of the hydrogen atoms on these aromatic rings are substituted with substituents such as halogen groups (especially chlorine), nitro groups, C1 to C3 alkyl groups (especially methyl groups), C1 to C3 alkoxy groups and the like. And those in which hydrogen in the amide bond constituting the polymer is substituted with other substituents.
[0032]
Such an aromatic polyimide solution is obtained as follows. That is, the polyamic acid used as a raw material can be prepared by reacting a tetracarboxylic acid dihydrate with an aromatic diamine in an aprotic organic polar solvent such as NMP, DMAc, or DMF. Then, the aromatic polyimide can be prepared by heating a solution containing the above polyamic acid or adding an imidizing agent such as pyridine to obtain a polyimide powder, which is dissolved again in a solvent. The polymer concentration in the film-forming stock solution is preferably about 5 to 40 wt%.
[0033]
Next, the solvent which is another component of the organic polymer solution is not particularly limited as long as the above-mentioned organic polymer can be dissolved. A salt may be contained, but when it is sealed at room temperature after preparation as a film-forming solution, it is preferable that it does not allow changes in turbidity on appearance or precipitation of organic polymer for more than one week. .
[0034]
In addition, the means for forming the solution is not particularly limited, and includes a method for directly obtaining an organic polymer solution by carrying out polymerization in the solvent as described above in addition to a known dissolving means.
[0035]
In addition, as long as the solution state can be stably maintained, a soluble organic substance or inorganic salt may be dissolved in the organic polymer solution, and the organic polymer is soluble in the solution solvent. A small amount of a solvent that does not dissolve alone may be mixed. Further, if necessary, a lubricant, an antioxidant or other additives may be blended to such an extent that physical properties are not impaired, and insoluble components such as organic or inorganic particles may be dispersed.
[0036]
These organic polymer solutions are then cast on a cast support such as an endless belt or drum. As a means for casting into a film or sheet, a conventionally known means can be adopted, and a method using a T-die, an L-die or the like is practical.
[0037]
In the present invention, in casting an organic polymer solution onto a support, the organic polymer and a solvent (mainly used for the solution) between the support and the organic polymer solution film to be cast ( A solvent (hereinafter referred to as an intervening solvent) having compatibility with the solvent (hereinafter referred to as a solution solvent) and a thickness T (μm) of the organic polymer solution film to be cast are referred to as an intervening solvent thickness t (μm). ) Is 0.001 ≦ t / T ≦ 0.1, preferably 0.001 ≦ t / T ≦ 0.01. When the t / T relationship is less than 0.001, the effect of suppressing air entrainment is small, and the casting speed does not increase. When the relationship exceeds 0.1, the cast organic polymer solution slips on the support. In some cases, flatness and surface properties may deteriorate. The term mainly used here means to be used exclusively for the purpose of dissolving the organic polymer, and may be one or more mixed solvents, and each component is incorporated into the organic polymer as a single component. It has compatibility. The compatibility mentioned here is defined as a solvent capable of forming a solution of 1% by weight or more, preferably 10% by weight or more at room temperature with respect to the organic polymer.
[0038]
The intervening solvent is compatible with the organic polymer. The compatibility mentioned here is defined as a solvent capable of forming a solution of 1% by weight or more, preferably 10% by weight or more at room temperature with respect to the organic polymer.
[0039]
The intervening solvent is also compatible with the solution solvent. The term "compatible" as used herein is defined as a solvent that is completely mixed even when mixed by 10% by weight with respect to the solution solvent, that is, is stabilized without forming a liquid-liquid interface when mixed.
[0040]
In addition, since the cast organic polymer solution becomes a molded product by removing the solvent, the intervening solvent is preferably made of the same type as the solvent mainly used for the solution solvent in consideration of post-treatment, etc. More preferably, the solution solvent is substantially the same. At this time, since the entropy change can be minimized, it is preferably employed from the viewpoint that problems such as deterioration caused by heat generation during mixing and evaporation of the solvent can be eliminated. The present invention employs such an intervening solvent, and 0.001 ≦ t / T ≦ 0.1, preferably 0.001 ≦ t / T ≦ 0.01 between the organic polymer solution and the support during casting. It is characterized by interposing so as to satisfy. As a result, the casting speed that cannot be obtained by the conventional solution casting method can be increased, and the quality of the obtained film, for example, the surface property and the flatness become extremely good. The excellent effect of the present invention is that since the affinity with the organic polymer and the solution solvent is good, the intervening solvent membrane is effectively and strongly interposed between the support and the cast organic polymer solution membrane. It is considered that air was prevented from being trapped by the film of the intervening solvent, and the casting speed was dramatically improved. In addition, since the intervening solvent is compatible with the organic polymer and the solution solvent, polymer precipitation and gelation at the support interface are prevented, and the intervening solvent is then absorbed into the organic polymer solution film. Therefore, it is considered that the surface quality and flatness of the final product are also improved.
[0041]
Next, the film forming apparatus used in the present invention will be described with reference to the drawings in order to explain in more detail. Of course, the present invention is not limited to this.
[0042]
The film forming apparatus used in the present invention comprises an extrusion means for extruding an organic polymer solution through a die, an endless belt or roll-shaped support for supporting the extruded organic polymer solution, and a solvent in the solution. In a film forming apparatus for obtaining a film or sheet-like molded body comprising means for removing and forming and means for gripping and extending the molded body as necessary, an extruded organic polymer solution and a support The gist of the invention is to have means for interposing a solvent having compatibility with the organic polymer and the solvent mainly used in the organic polymer solution in between.
[0043]
That is, in the film forming apparatus shown in FIG. 1, the T die 1 serves as an extruding means for extruding the organic polymer solution, and the cast drum is provided close to the T die 1 as a support for supporting the extruded organic polymer solution. 7 is provided. And between the organic polymer solution film 5 extruded from the T-die 1 and the cast drum 7, the organic polymer and a solvent having compatibility with the solvent mainly used for the organic polymer solution are interposed. A caulking means, that is, a solvent applicator B is provided on the upstream side of the T die 1. The solvent applicator B is moved by the press contact mechanism 3 so that the position adjustment is possible.
[0044]
In this example, the contact device A is further provided as means for bringing the organic polymer solution film 5 into close contact with the support 7. The contact apparatus A has an air knife nozzle 6 provided on the downstream side of the T die 1, and air is fed into the air knife nozzle 6 by a known means. The blowing pressure is controlled by the slit width of the pressure gauge 2 and the air knife nozzle 6.
[0045]
The solvent applicator B may be a device that contacts the cast support as shown in FIG. 1 to apply the intervening solvent on the support, or a device that applies non-contact as shown in FIGS. However, since there is no friction with the support and there is little fear of scratching, it is preferable to employ a non-contacting method.
[0046]
As shown in FIG. 1, the contact-type solvent applicator includes, for example, a liquid feed pump 9, an intervening solvent supply means for extruding intervening solvent by sending air into a tank, and an intervening solvent supply pipe for supplying the intervening solvent. 4 and a roll-like, plate-like, or rod-like intervening made of a material such as sponge, cloth, absorbent, which holds the intervening solvent supplied through the intervening solvent supply pipe 4 and has a function of applying the intervening solvent to the support. It is comprised from the solvent application body 8 and the intervening solvent application body support press-contacting mechanism 3 which press-contacts the said intervening solvent application body 8 to a cast support body as needed.
[0047]
This will be described in more detail with reference to FIG. An intervening solvent discharge tube 10 that feeds an intervening solvent is penetrated through the roll intervening solvent application body 8 so as to be connected to the intervening solvent supply tube 4. The outer periphery of the intervening solvent discharge pipe 10 has a large number of pores and is adjusted on the liquid feed pump 9 (not shown) side so that the intervening solution holding amount of the intervening solvent application body 8 is always a constant amount. Has been. In addition, an intervening solvent application body supporting press contact mechanism 3 is connected so as to support the intervening solvent discharge pipe 10 and the like as required while maintaining the pressure on the cast drum 7 constant.
[0048]
FIG. 3 shows an example in which a cast belt 12 is used as a support for supporting the organic polymer solution film 5 and a non-contact type intervening solvent applying apparatus is used as the intervening solvent applying apparatus B.
[0049]
That is, the organic polymer solution 5 extruded from the T die 1 is extruded onto the cast belt 12 driven by the cast belt driving drum 7 '.
[0050]
The non-contact type solvent application apparatus is shown by B in FIG. 3, and directly supplies the intervening solvent through the intervening solvent supply pipe 4 to the vaporizer or atomizer 13 composed of a spray nozzle, a heating device, a vibrating membrane, and the like. Alternatively, atomization is performed and an intervening solvent is applied onto the cast belt 12. When the intervening solvent is vaporized, the temperature of the cast belt 12 can be reduced and condensed on the belt.
[0051]
The adjustment of the uniformity of the overall application amount or the application amount in the longitudinal direction is adjusted by the intervening solvent supply means, that is, the liquid feed pump 9 (not shown), and the adjustment of the application amount in the width direction is performed by the vaporizer. Or it can achieve by controlling the arrangement | positioning space | interval with respect to the width direction in the atomizer 13, the back pressure of the intervening solvent for every container, supply_amount | feed_rate, etc. In addition, the non-contact type solvent application device includes a vaporizer or an atomizer 13 so that excessive vaporized or atomized intervening solvent that does not adhere to the support as shown in the figure does not leak out of the system. It is possible to provide a means for exhausting by providing a chamber 14 so as to cover the air and disposing an exhaust pipe 15 connected to a suction means such as an intake blower. In addition, the chamber 14, the introduction pipe 4, the exhaust pipe 15, etc. may be heated so that condensed or attached intervening solvent does not drip onto the cast support, or a recovery mechanism such as soot is provided at the edge of the chamber 14. it can.
[0052]
Further, in this example, the contact device A is further provided as means for bringing the organic polymer solution film 5 into close contact with the cast belt 12. The contact device A has a suction nozzle 11 provided on the upstream side of the T-die 1, and the suction nozzle 11 sucks air by a known means such as a suction blower. The suction pressure including the distribution in the width direction is controlled by the configuration of the opening of the pressure gauge 2 and the suction nozzle 11 or the like.
[0053]
FIG. 4 shows an example in which a cast drum 7 is used as a support for supporting the organic polymer solution film 5 and a non-contact type intervening solvent application apparatus different from that shown in FIG.
[0054]
In this example, instead of directly vaporizing or atomizing to provide an intervening solvent, a vaporizer or atomizing device using a spray nozzle, a heating device, a vibrating membrane or the like in a separately provided vaporizing chamber or atomizing chamber 18. A vessel 13 is provided to vaporize or atomize the intervening solvent in the chamber. Then, if necessary, the carrier gas is sent from the air supply pipe 16 into the vaporization chamber or the atomization chamber, introduced from the introduction pipe 17 into the discharger 19 provided in the chamber 14, and guided onto the cast drum 7 to be attached. .
[0055]
In this example as well, when the vaporized intervening solvent is used, the cast support temperature may be decreased and condensation may be performed on the cast support. Further, a chamber 14 was provided so as to cover the discharger 19 so that excessive vaporized or atomized intervening solvent that did not adhere to the support did not leak out of the system, and was connected to suction means such as an intake blower. A means for exhausting by disposing the exhaust pipe 15 can be provided. Further, the vaporization or atomization chamber 18, the chamber 14, the introduction pipe 17, the exhaust pipe 15 and the like are heated so that the condensed solvent or adhering intervening solvent does not drip onto the cast support, and soot is formed on the edge of the chamber 14 or the like. A recovery mechanism can be provided.
[0056]
5 and 6 show another embodiment of the present invention. That is, in the film forming apparatus shown in FIGS. 5 and 6, the T die 1 is used as an extruding means for extruding an organic polymer solution, and the T die 1 is used as a support for supporting the extruded organic polymer solution. A cast drum 7 is provided. In these examples, an intervening solvent film is formed on the extruded organic polymer thin film side and then cast on the cast drum 7.
[0057]
FIG. 5 shows a cross section of the T die 1. The organic polymer body and the organic polymer body are disposed between the organic polymer solution film 5 extruded from the T die 1 and the cast drum 7. As a means for interposing a solvent compatible with the solvent mainly used in the solution, an intervening solvent supply capillary 20 using a capillary or a porous body connected to the intervening solvent supply pipe 4 is provided at the bottom of the T die. Immediately after the organic polymer solution film 5 is extruded, an intervening solvent is applied to the solution. The amount of the intervening solvent applied is adjusted on the side of the liquid feed pump 9 (not shown) connected to the other end of the solvent supply pipe 4. This can be achieved by adjusting.
[0058]
FIG. 6 also shows a cross section of the T-die 1. In this case, the T-die is used as a means for interposing a solvent having compatibility with the organic polymer and the solvent mainly used in the organic polymer solution. The intervening solvent supply tube 4 and the intervening solvent supply thin tube 20 ′ are introduced therein, the intervening solvent is laminated on the organic polymer solution, and discharged together from the T die. The application amount of the intervening solvent is adjusted on the side of the liquid feed pump 9 (not shown) connected to the other end of the solvent supply pipe 4, and the adjustment of the application quantity in the width direction is performed by adjusting the width of the supply pipe in the T die. This can be achieved by appropriately adjusting the configuration.
[0059]
Of course, in order to increase the adhesion of the polymer solution, the adhesion apparatus described with reference to FIGS. 1 and 2 can also be used in the system shown in FIGS.
[0060]
As shown in FIGS. 1 to 4, in the present invention, it is extremely preferable to use a means for exerting a force on the polymer solution film and bringing it into close contact with the support. Such means include means for sucking air upstream of the cast organic polymer solution film such as the suction nozzle and air knife described above, means for blowing a working fluid such as air downstream, electrostatic force and magnetic force. It is preferable to use a known means such as a means for exerting an indirect force such as a fine adjustment mechanism for the attachment position. Of course, you may combine arbitrarily with the said solvent provision apparatus. Surprisingly, when used in combination with the present invention, the blowing pressure, suction pressure, etc., which these means conventionally required for stabilization are drastically reduced. As a result, it is possible to operate at a low load even at a speed that could not be achieved by these stabilization methods in the past, and the present invention is preferably combined with this action to further increase the speed. Further, in the case of the close contact means using the air flow, the pressure fluctuation is suppressed by the reduction of the necessary pressure, and it works advantageously in thin film formation.
[0061]
The embodiment shown in FIGS. 5 and 6 is preferably employed when it is necessary to preheat the cast support or when other processing is performed.
[0062]
Further, it is preferable that the intervening solvent has an application amount variation of 30% or less, preferably 20% or less, and more preferably 10% or less on the effective surface to which it is applied. If it exceeds 30%, dry spots occur in the film-forming means that employs heat evaporation especially for the removal of the solvent, and there is concern that the physical properties of the obtained film or sheet-like molded product may become non-uniform and flatness. There is a concern of getting worse. The effective surface referred to here is defined as the surface that is actually cast, and the dispersion of the applied amount is defined as the maximum deviation rate with respect to the average value obtained by measuring the applied amount per unit area in the longitudinal direction or the width direction. To do. For the application, a mechanism capable of adjusting the contact pressure in the width direction is used in the intervening solvent application body supporting pressure welding apparatus 3 of FIG. 1, or the supply pipe, vaporizer or atomizer 13 of FIG. 3, or the discharger 19 of FIG. This can be achieved by appropriately using a distributor, optimizing the arrangement of supply elements such as supply holes and generators, or providing a partition plate in the chamber 14.
[0063]
When the organic polymer solution is extruded from the slit using a T-die or the like, the distance between the extrusion port and the cast support is preferably 10 mm or less, preferably 5 mm or less, more preferably 3 mm or less. When it exceeds 10 mm, even if an intervening solvent is used, there is little merit in speeding up, and the landing line of the extruded organic polymer solution film is likely to be shaken, which may cause uneven thickness. In addition, the thickness of both ends increases due to the occurrence of neck-in, the amount of solvent removal per unit area increases, peeling off from the support does not work, and the physical properties of the obtained film or sheet-like molded product are not uniform. This is undesirable.
[0064]
Although there is no particular limitation on the thickness of the film or sheet-like molded product obtained in the present invention, as described above, since the conventional technique has a great technical limitation in the molding of a particularly thin one, the present invention is a film or sheet-shaped molding. The final thickness of the body is preferably 10 μm or less, preferably 7 μm or less, more preferably 5 μm or less, and particularly preferably 4 μm or less.
[0065]
In particular, the present invention is further excellent in the surface properties and flatness of a film or sheet-like molded product, so that it is required to increase the capacity more and more, and the base material for magnetic recording media and the reduction in size and weight that are strict with such requirements. It is preferably used as an insulating wiring member for electric equipment such as a flexible printed circuit board, a TAB carrier tape, and a solar battery substrate, a capacitor, or a base material for a transfer material for thermal recording.
[0066]
In particular, since the film or sheet-like molded product obtained from the present invention is excellent in surface properties, a measurement area of 0.002 mm at a cutoff value of 0.08 mm measured with an optical stylus type three-dimensional surface roughness meter.²3D surface roughness SRa1 and measurement area 1.0mm²The three-dimensional surface roughness SRa2 at 1 preferably satisfies the following relationship.
[0067]
[Expression 1]

[0068]
SRa2 / SRa1 is preferably 3.5 or less, more preferably 3.0 or less. When SRa2 / SRa1 exceeds 4.5, the surface of the substrate is significantly undulated, and there are many restrictions on its use as a product.
[0069]
SRa2 / SRa1 is preferably 0.9 or more, and more preferably 1.2 or more. If SRa2 / SRa1 is less than 0.8, there is a concern that processing problems may occur, and the friction durability of the final product may be adversely affected.
[0070]
Furthermore, the film or sheet-like molded product obtained by the present invention preferably has a tensile Young's modulus in at least one direction at 20.degree. C. and a relative humidity of 60% of 7.84 GPa. More preferably, it is 8.82 GPa or more, More preferably, it is 9.8 GPa or more. In general, Young's modulus is governed by the molecular structure and stretchability during film formation, and the para-oriented aromatic polyamide described above is preferably employed as a material having a high Young's modulus. Usually, the upper limit is about 35 GPa, and a film having a value higher than this is brittle or easily torn, and its industrial value is low. Since it can withstand the tension during use or processing, it is particularly advantageous for a thin-film molded body.
[0071]
In addition, the present invention can be used for molding a single-layer film or a sheet-like molded body, but is also preferably used for molding a laminated molded body. The components constituting each layer at the time of lamination may be the same or different. Further, at least one layer constituting each layer may contain auxiliary materials such as particles that do not impair the object of the present invention, and the types, contents, particle sizes, etc. of these auxiliary materials may be the same or different. There may be.
[0072]
The organic polymer solution film cast through the above means is processed into a film or sheet-like molded body by a so-called solution casting method. The solution casting method includes a dry-wet method, a dry method, a wet method, and the like, and any method can be used to form a film. Here, the dry-wet method will be described as an example.
[0073]
In the case of forming a film by a dry / wet method, a conventionally known method disclosed in, for example, JP-A-54-105197 is used. That is, the solvent is evaporated from the thin film layer of the organic polymer solution cast on the cast support and the thin film is dried until it has self-holding property. Drying conditions are in the range of room temperature to 220 ° C. and within 60 minutes, preferably in the range of room temperature to 200 ° C. The film after the dry process is peeled off from the support and introduced into a wet process in which desalting, desolvation and the like are performed with an extraction medium in a bath similar to the wet process, and in addition, stretching, drying, and heat treatment are performed.
[0074]
The film or sheet-like molded body formed as described above is stretched by a conventionally known method such as stretching while being held by a clip in the tenter or utilizing the difference in the peripheral speed of the roll during the film forming process. However, the draw ratio is 0.8 to 8.0 in terms of area ratio (the area ratio is defined by a value obtained by dividing the film area after stretching by the area of the film before stretching. 1 or less means relaxation ) Is preferably within the range of 1.1 to 5.0. Further, it is effective to gradually cool the film after stretching or heat treatment, and it is effective to cool at a rate of 50 ° C./second or less.
[0075]
The film or sheet-like molded product obtained in the present invention may be laminated. For example, in the case of two layers, the organic polymer solution is divided into two, and the necessary auxiliary materials are added to the respective layers. Or the like is used. The same applies to the case of three or more layers. As a method of laminating, a known method such as laminating in a base, laminating in a composite tube, or a method of once forming one layer and forming another layer thereon can be employed.
[0076]
[Methods for measuring physical properties and methods for evaluating effects]
The characteristic value measurement method and effect evaluation method of the present invention are as follows.
[0077]
A. Young's modulus, elongation
Using Tensilon manufactured by Orientec Co., Ltd., the test width was 10 mm, the test length was 50 mm, and the tensile speed was 300 mm / min. In the measurement, the sample was placed in an atmosphere of 20 ° C. and 60% relative humidity for 24 hours or more, and the measurement was performed under the conditions.
[0078]
B. Surface properties
The film surface was vapor-deposited with a vacuum vapor deposition machine, and the vapor deposition surface was observed with a differential interference microscope to examine the presence or absence of defects that would cause practical problems. If there is a defect, it is indicated as x, and if there is no defect, it is indicated as ○.
[0079]
C. Thick spot
Using an electron beam micro thickness meter, the length of 10 m was continuously measured in the longitudinal direction of the film, and the value obtained by dividing the difference between the maximum value and the minimum value by the average thickness was multiplied by 100 (unit: %). In addition, the thickness unevenness was indicated by ○ mark as good when less than 10%, indicated by ◎ as best at 5% or less, and indicated by × as bad at 10% or more.
[0080]
D. Flatness evaluation index
Place a 50 cm x 50 cm film on a flat plate with a thick felt or non-woven fabric ("EXSEINE" manufactured by Toray Industries, Inc. was used in this example) in an environment of 25 ° C and 60% relative humidity. Spread with a brush. After leaving still for 15 minutes, the swelled part is marked without contacting on the exenu, and the area is calculated | required. Then, the value obtained by dividing the area of the non-contact portion by the total area of the film is multiplied by 100 (unit:%), less than 10% is indicated as good by ◯, and 5% or less is indicated by ◎ as the best, 10% or more was shown as “x” as defective.
[0081]
E. Cast stability
When the organic polymer was cast on a stainless steel belt, the case where there was no problem was indicated by ◯, and the case where the organic polymer film was broken periodically or intermittently was indicated by X.
[0082]
F. SRa2 / SRa1
The measurement was performed by the method described above, and those satisfying 0.8 ≦ SRa2 / SRa1 ≦ 4.5 were indicated as “good” and indicated as “good”, and those other than that were indicated as “poor”.
[0083]
【Example】
Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to such description.
[0084]
The following was used as the organic polymer solution. 2-chloroparaphenylenediamine corresponding to 80 mol% as an aromatic diamine component and 4,4′-diamino corresponding to 20 mol% in NMP in which silica particles having an average primary particle diameter of 16 nm are dispersed in an amount of 0.3 wt% per polymer. Diphenyl ether was dissolved, and 2-chloroterephthalic acid chloride corresponding to 100 mol% as an acid chloride component was added thereto and stirred for 2 hours to complete the polymerization. Next, the generated hydrogen chloride was neutralized by adding one-fourth at a time using lithium hydroxide to obtain an aromatic polyamide solution having a polymer concentration of 10% by weight.
[0085]
Example 1
A 400 mm wide T-die placed 2 mm above the cast support as an extrusion means for the organic polymer solution and connected to the gear pump, a mirror-polished stainless steel belt and a cast roll for driving the belt As a means for close contact, a suction nozzle with a slit clearance of 1.5 mm is arranged on the upstream side of the T die as a contact means, and then a solvent (NMP) supply tank and a supply pump are connected on the upstream side of the suction nozzle as means for applying an intervening solvent. It was connected to a chamber provided on the upstream side of the suction nozzle via an atomization chamber equipped with a nozzle air sprayer, a blower and a filter through which air is introduced, and an atomizer discharge port (condensate cast belt To prevent falling down, the discharge port of the atomized body provided with ridges on the edge is provided 2mm above the cast belt. . And it is) used indirect supply unit, a gear pump to an aromatic polyamide solution prepared above from the hopper, 2 [mu] m cut filter - through, was cast in a thickness of 60μm on a stainless steel belt 65 ° C. from the T-die. At this time, the amount of NMP applied to the cast belt was 0.5 μm ± 0.05 μm (the error range shown in this example is based on the above-described method for measuring the amount applied per unit area on the effective surface). The pressure in the suction nozzle was -50 mmAq.
[0086]
Next, while maintaining the NMP application amount at 0.5 μm ± 0.05 μm, the speed was gradually increased while adjusting the discharge amount and the speed of the cast belt so that the final film thickness was constant. Casting could be carried out very stably without any air being trapped between the organic polymer solution membrane and the support.
[0087]
Next, while being held on the cast belt, the solvent was evaporated by heating with a hot air of 190 ° C. in a dryer for 1.5 minutes, and the film having self-holding property was continuously peeled from the belt. Next, the film is introduced into a heated water tank, the residual solvent and the inorganic salt produced by neutralization are extracted with water, dried with a tenter and heat-treated, and an aromatic polyamide film having a thickness of 3.7 μm. Got. In the water tank, the roll peripheral speed was changed to 1.25 times in the longitudinal direction of the film, dried and stretched while being held by a clip in a tenter at 280 ° C. for 1.5 minutes, and stretched 1.3 times in the width direction. Subsequently, heat treatment was performed at 290 ° C. for 30 seconds under a constant length, followed by slow cooling at a rate of 20 ° C./second.
[0088]
SRa2 / SRa1 of this base film was 1.35, Young's modulus was 13 GPa and 13 GPa, and the elongation was 40%, respectively in the longitudinal and width directions.
Further, there was no problem in the surface property, the thickness unevenness was 4%, and the flatness evaluation index was 4%, which was extremely excellent in practical use.
[0089]
Examples 2-4
Example 1 except that the polymer film thickness cast on a stainless steel belt was 10, 30, 120 μm, and the amount of NMP applied was 0.08 μm ± 0.008 μm, 0.25 μm ± 0.025 μm, 1.0 μm ± 0.1 μm The cast was performed on the cast belt in the same manner as above. The evaluation results of the film are shown in Table 1.
[0090]
  referenceExample1
  Casting was performed on the cast belt in the same manner as in Example 1 except that the pressure in the suction nozzle was set to 0 mmAq. While the NMP application amount was kept at 0.5 μm ± 0.05 μm, the speed was gradually increased while adjusting the discharge amount and the speed of the cast belt so that the final film thickness was constant, and the casting speed was 15 m / min. However, casting could be carried out very stably without air being caught between the organic polymer solution film and the support. Next, conditions were adjusted so that the same conditions as in Example 1 were obtained, and an aromatic polyamide film having a thickness of 3.7 μm was obtained. SRa2 / SRa1 of this base film was 1.30, Young's modulus was 13 GPa and 13 GPa, and the elongation was 40%, respectively in the longitudinal and width directions. Further, there was no problem in the surface property of this film, the thickness unevenness was 7%, and the flatness evaluation index was 6%.
[0091]
Example 6
As an intervening solvent supply means, an aromatic polyamide solution prepared by the same method and conditions as in Example 1 except that a sponge roll equipped with an intervening solvent supply mechanism and a pressing mechanism to the cast belt is disposed, from a hopper to a gear pump. It was cast from a T die onto a 65 ° C. stainless steel belt through a 2 μm cut filter. At this time, NMP was applied from the sponge roll onto the cast belt so as to be 4 μm ± 0.3 μm (the error range shown in this example is based on the above-described method for measuring the applied amount per unit area on the effective surface).
[0092]
Next, while maintaining the NMP application amount at 4 μm ± 0.3 μm, the speed was gradually increased while adjusting the discharge amount and the speed of the cast belt so that the final film thickness was constant, even at a casting speed of 45 m / min. Casting was able to be carried out very stably without entraining air between the organic polymer solution membrane and the support. The conditions were adjusted so as to satisfy the same conditions as in Example 1 to obtain an aromatic polyamide film having a thickness of 3.6 μm.
[0093]
SRa2 / SRa1 of this base film was 1.5, Young's modulus was 13 GPa and 13 GPa, and the elongation was 40%, respectively in the longitudinal direction and the width direction.
Moreover, both the surface property and flatness of this film were inferior to the film of Example 1.
[0094]
Comparative Example 1
The same system as in Example 1 was used except that the intervening solvent supply mechanism was removed and no intervening solvent was applied onto the cast belt.
When the speed was gradually increased while adjusting the discharge amount and the speed of the cast belt so that the final film thickness was constant, when the pressure in the suction nozzle was -50 mmAq, air was trapped at 13 m / min. As a result, film formation became impossible. Next, while increasing the pressure in the suction nozzle, the discharge rate and the speed of the cast belt were adjusted so that the final film thickness would be constant, and the speed was increased. When the pressure in the suction nozzle is further lowered, the shake of the discharged organic polymer solution film is increased, and generation of uneven thickness is recognized.
About what was cast at said 13 m / min, conditions were adjusted so that it might become the conditions similar to Example 1 below, and the 3.6-micrometer-thick aromatic polyamide film was obtained.
[0095]
SRa2 / SRa1 of this base film was 1.8, Young's modulus was 13 GPa and 13 GPa, and the elongation was 41%, respectively in the longitudinal and width directions.
Moreover, although the film surface property was not practically problematic, the thickness variation was 13% and the flatness evaluation index was 12%, which was not satisfactory in practical use.
[0096]
Comparative Example 2
In Comparative Example 1, casting was performed with the suction nozzle internal pressure further reduced to 0, but air was caught at 7 m / min.
[0097]
Comparative Examples 3-6
The same method as in Example 1 except that the polymer film thickness cast on the stainless steel belt is 10, 30, 60, 120 μm NMP is 3.3 μm ± 0.33 μm, 10 μm ± 1 μm, 20 μm ± 2 μm, 40 μm ± 6 μm Then cast on the cast belt. Table 1 shows the evaluation results of the films that could be formed.
[0098]
About Comparative Examples 3-6, neck-in generate | occur | produces immediately after the casting start, and generation | occurrence | production of thickness unevenness is recognized in a film edge part.
[0099]
Next, while increasing the pressure in the suction nozzle, the NMP application amount was kept constant, and the discharge amount and the speed of the cast belt were adjusted so that the final film thickness was constant. Then, from the beginning of the suction, in Comparative Example 4, the suction nozzle internal pressure is less than −10 mmAq, and in Comparative Example 5, the suction nozzle internal pressure is less than −30 mmAq. When the pressure in the suction nozzle was lowered from -15, -40, and -100 mmAq, generation of uneven thickness was observed due to the influence of the shake of the discharged organic polymer solution film. The evaluation results of the film of Comparative Example 6 are shown in Table 1.
[0100]
[Table 1]

[0101]
【The invention's effect】
By adopting the above-described configuration, the present invention enables high-speed film formation even in the case of a thin film, particularly in the problem of high-speed film formation in solution film formation, which has been difficult until now. Further, the obtained film or sheet-like molded product can be excellent in surface properties and flatness.
[0102]
The film or sheet-like molded product thus obtained is used in various applications such as optical members, optical recording media, magnetic recording media, insulating wiring members for electrical equipment, condensers, coating materials, printing materials such as plate making materials, and photographic films. Can be suitably used.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing one embodiment of the present invention.
FIG. 2 is an enlarged explanatory view of a cast support contact portion of the contact-type solvent applying apparatus in FIG.
FIG. 3 is an explanatory diagram showing one embodiment of the present invention.
FIG. 4 is an explanatory diagram showing one embodiment of the present invention.
FIG. 5 is an explanatory view showing a cross section of a T-die portion.
FIG. 6 is an explanatory view showing a cross section of a T-die portion.
[Explanation of symbols]
A: Contact device
B: Solvent application device
1: T die
2: Pressure gauge
3: Intervening solvent application body support pressure welding mechanism
4: Intervening solvent supply pipe
5: Organic polymer solution film
6: Air knife nozzle
7: Cast drum
7 ': Cast belt driving drum
8: Intervening solvent application body
9: Liquid feed pump
10: Intervening solvent discharge tube
11: Suction nozzle
12: Cast belt
13: Vaporizer or atomizer
14: Chamber
15: Exhaust pipe
16: Air pipe
17: Introduction pipe
18: Vaporization room or atomization room
19: Ejector
20, 20 ′: interposed solvent supply capillary

Claims (4)

In a method of casting a solution of aromatic polyamide and / or aromatic polyimide on a support and removing the solvent in the solution to obtain a film or sheet-like molded product, means for bringing the solution into close contact with the support is used. with cast Te, polymer cast as a liquid film thickness t ([mu] m) during casting mainly solvents used and the kind of solvent in the solution between the solution a liquid film which is the support and the cast A film forming method, wherein the casting is performed such that the thickness T (μm) satisfies the relationship of the following formula:
0.001 ≦ t / T ≦ 0.1 The film forming method according to claim 1, wherein the dispersion of the applied amount with respect to the effective surface of the solvent to be interposed is 30% or less of the average value. The film forming method according to claim 1 or 2 , wherein the distance between the extrusion port of the aromatic polyamide and / or aromatic polyimide solution and the support is 10 mm or less. The film forming method according to any one of claims 1 to 3 , wherein a solution of the aromatic polyamide and / or the aromatic polyimide is cast so that the final thickness of the film or the sheet-like molded product is 10 µm or less.

Images