JP4595291B2 - Polyimide film and method for producing the same - Google Patents

Description

【００１７】
上記式１において、Ｒ１は少なくとも１個の芳香族環を有する４価の有機基で、その炭素数は２５以下であるものとし、Ｒ１に結合する２つのカルボキシル基の夫々はＲ１における芳香族環のアミド基が結合する炭素原子とは相隣接する炭素原子に結合しているものであり、またＲ２は少なくとも１個の芳香族環を有する２価の有機基で、その炭素数は２５以下であるものとし、アミノ基はＲ２における芳香族環の炭素原子に結合しているものである。
【００１８】
上記の芳香族テトラカルボン酸類の具体例としては、ピロメリット酸、３，３’，４，４’−ビフェニルテトラカルボン酸、２，３’，３，４’−ビフェニルテトラカルボン酸、３，３’，４，４’−ベンゾフェノンテトラカルボン酸、２，３，６，７−ナフタレンジカルボン酸、２，２−ビス（３，４−ジカルボキシフェニル）エーテル、ピリジン−２，３，５，６−テトラカルボン酸及びこれらのアミド形成性誘導体が挙げられる。ポリアミド酸の製造にあたってはこれらの酸無水物が好ましく使用される。
【００１９】
上記の芳香族ジアミン類の具体例としては、パラフェニレンジアミン、メタフェニレンジアミン、ベンチジン、パラキシリレンジアミン、４，４’−ジアミノジフェニルエーテル、４，４’−ジアミノジフェニルメタン、４，４’−ジアミノジフェニルスルホン、３，３’−ジメチル−４，４’−ジアミノジフェニルメタン、１，５−ジアミノナフタレン、３，３’−ジメトキシベンチジン、１，４−ビス（３メチル−５アミノフェニル）ベンゼン及びこれらのアミド形成性誘導体が挙げられる。中でも、少なくともパラフェニレンジアミンを含有させることが好ましい。
【００２０】
本発明で使用される有機溶媒の具体例としては、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドンなどの有機極性アミド系溶媒が挙げられ、これらの有機溶媒は単独で又は２つあるいはそれ以上を組み合わせて使用してもよい。また、ベンゼン、トルエン、キシレンのような非溶媒と組み合わせて使用してもよい。
【００２１】
本発明で用いるポリアミド酸の有機溶媒溶液は、固形分を５〜４０重量％、好ましくは１０〜３０重量％を含有しており、またその粘度はブルックフィールド粘度計による測定値で５００〜２００００ポイズ、好ましくは、１０００〜１００００ポイズのものが安定した送液のために好ましい。
【００２２】
また、有機溶媒溶液中のポリアミド酸は部分的にイミド化されてもよく、少量の無機化合物を含有してもよい。
【００２３】
本発明において、芳香族テトラカルボン酸類と芳香族ジアミン類とはそれぞれのモル数が大略等しくなる割合で重合されるか、その一方が１０モル％、好ましくは５モル％の範囲内で他方に対して過剰に配合されてもよい。
【００２４】
重合反応は有機溶媒中で撹拌および／または混合しながら、０〜８０℃の温度の範囲で１０分〜３０時間連続して進められるが、必要により重合反応を分割したり、温度を上下させてもかまわない。両反応体の添加順序には特に制限はないが、芳香族ジアミン類の溶液中に芳香族テトラカルボン酸類を添加するのが好ましい。重合反応中に真空脱泡することは、良質なポリアミド酸の有機溶媒溶液を製造するのにとって有効な方法である。また、重合反応の前に芳香族ジアミン類に少量の末端封止剤を添加して重合反応を制御することを行ってもよい。
【００２５】
本発明で使用される閉環触媒の具体例としては、トリメチルアミン、トリエチレンジアミンなどの脂肪族第３級アミン及びイソキノリン、ピリジン、ベータピコリンなどの複素環第３級アミンが挙げられるが、複素環式第３級アミンから選ばれる少なくとも一種類のアミンを使用するのが好ましい。
【００２６】
本発明で使用される脱水剤の具体例としては、無水酢酸、無水プロピオン酸、無水酪酸などの脂肪族カルボン酸無水物、及び無水安息香酸などの芳香族カルボン酸無水物が挙げられるが、無水酢酸および／または無水安息香酸が好ましい。
【００２７】
ポリアミド酸に対する閉環触媒及び脱水剤の含有量は、次の式１、２
【００２８】
【数１】

【００２９】
【数２】

【００３０】
となるようにするのが好ましい。またアセチルアセトンなどのゲル化遅延剤を併用してもよい。
【００３１】
以下に、上記ポリアミド酸の有機溶媒溶液からポリイミドフィルムを製造する方法について具体的に説明する。
【００３２】
まず、ゲルフィルムを成膜する方法としては、閉環触媒及び脱水剤を含有しないポリアミド酸の有機溶媒溶液をスリット付き口金から支持体上に流延してフィルムに成形し、支持体上で加熱乾燥することにより自己支持性を有するゲルフィルムとなした後、支持体より剥離し、更に高温下で乾燥熱処理することによりイミド化する熱閉環法、及び閉環触媒及び脱水剤を含有せしめたポリアミド酸の有機溶媒をスリット付き口金から支持体上に流延してフィルム状に成形し、支持体上でイミド化を一部進行させて自己支持性を有するゲルフィルムとした後、支持体より剥離し、加熱乾燥／イミド化し、熱処理を行う化学閉環法が代表的な方法である。
【００３３】
本発明では、どちらの閉環方法を採用してもよいが、化学閉環法はポリアミド酸の有機溶媒溶液に閉環触媒および脱水剤を含有設備を必要とするものの、自己支持性を有するゲルフィルムが短時間で得られる点でより好ましい。
【００３４】
ポリアミド酸に閉環触媒及び脱水剤を含有せしめる方法としては、ポリアミド酸の有機溶媒溶液と閉環触媒及び脱水剤を回転式混合機で混合する方法、ポリアミド酸の有機溶媒溶液を静的混合機に送り込みながら該静的混合機の直前で閉環触媒及び脱水剤を注入する方法、ポリアミド酸の有機溶媒溶液を支持体上に流延した後閉環触媒及び脱水剤に接触させる方法などが挙げられるが、閉環触媒及び脱水剤の含有量及びその均一性の面からは、混合機で混合して閉環触媒と脱水剤とポリアミド酸の有機溶媒溶液との混合液をスリット状口金に送り込む方法が好ましい。
【００３５】
この際には、上記混合液の粘度が１００〜１００００ポイズとなるように、固形分濃度と温度を調整する必要がある。この混合液はポリアミド酸が熱閉環反応し粘度が著しく高くなり口金から吐出できなくなる性質を持っているため、低温（例えば−１０℃）に保持する必要がある。
【００３６】
上記混合液は、スリット状口金を通ってフィルム状に成型され、加熱された支持体上に流延され、支持体上で熱閉環反応をし、自己支持性を有するゲルフィルムとなって支持体から剥離される。支持体は金属製の回転ドラムやエンドレスベルトであり、その温度は液体または気体の熱媒により、および／または電気ヒーターなどの輻射熱により制御される。
【００３７】
ゲルフィルムは、支持体からの受熱および／または熱風や電気ヒータなどの熱源からの受熱により、３０〜２００℃、好ましくは４０〜１５０℃に加熱されて閉環反応し、遊離した有機溶媒等の揮発分を乾燥させることにより自己支持性を有するようになり、次いで支持体から剥離される。
【００３８】
支持体から剥離されたゲルフィルムは、固形分に対して主たる揮発分の含有率が４００重量％以上の状態である。
【００３９】
このゲルフィルムは、回転ロールにより走行速度を規制しながら走行方向に延伸されるのが好ましい。延伸は１４０℃以下の温度で１．０５〜１．９倍、好ましくは、１．１〜１．６倍、さらに好ましくは、１．１〜１．５倍の倍率で実施される。
【００４０】
走行方向に延伸されたゲルフィルムは、テンター装置に導入され、テンタークリップに幅方向両端部を把持されて、テンタークリップと共に走行しながら、固形分に対して主たる揮発分の含有率が４００重量％以上の状態で、幅方向へ１４０℃以下の温度で延伸される。ここでは、乾燥ゾーンに入るまでに、総横延伸量の５０％以上を完了することが重要な要件である。すなわち、揮発分の含有率が４００重量％未満の状態になると、延伸むらが生じやすく、たるみ量が悪化するため、揮発分の含有率が４００重量％以上の状態での幅延伸倍率を総幅延伸倍率の５０％以上延伸する必要がある。
【００４１】
次いで、ゲルフィルムを、乾燥ゾーンに導入して乾燥しながら横延伸を行い、幅方向の総延伸倍率を１．３倍から１．６倍とする。この工程のフィルム両端を固定して幅方向に延伸するにあたっては、従来はフィルムの幅方向の急激な延伸によりフィルムが破れることやフィルム両端で固定しているピンまたはクリップ部から裂けることなどの不具合を防ぐために、支持体から剥離したフィルムをフィルム中の溶媒量が４００重量％以上の範囲においては１．３倍より小さくするというのが通常であった。したがって、フィルムの幅方向に関して中央部と両端部で物性の差異が生じることがあった。
【００４２】
溶媒量の乾燥ゾーンにおいては、熱風などにより加熱される前に、漏れ込みエアーと加熱エアーとを排気できるノズルを設置して、乾燥ゾーン内でのフィルム乾燥後の溶媒を含んだエアーと漏れ込みエアーとの混合を防ぐことが望ましい。乾燥ゾーンでの熱風温度は、２００〜３００℃が好ましい。また熱風だけでなく、輻射加熱を使用してもよい。
【００４３】
上記の乾燥ゾーンで乾燥したフィルムは、熱風、赤外線ヒーターなどで１５秒から１０分加熱される。次いで、熱風および／または電気ヒーターなどにより、２５０から５００℃の温度で１５秒から２０分熱処理を行う。この場合に急激に加熱すると、平面性を失うため、加熱方法を適宜選択する必要がある。熱処理されたフィルムは、冷却された後巻き取られる。
【００４４】
巻き取られた原反フィルムは、適宜スリットされる。なお、本発明のポリイミドフィルム中には、本発明の目的を阻害しない範囲で、高強度化などの目的で異種ポリマーをブレンドしてもよい。また、酸化防止剤、熱安定剤、紫外線吸収剤、遮光剤、耐電防止剤などの有機添加剤を通常添加される程度添加されていてもよい。さらに、原反フィルムには、プラズマ処理やコロナ放電処理などの易接着性処理がされていてもよい。
【００４５】
２００℃の熱収縮量を低下させるためには、特開平３−５５２３２号公報、特開平３−５５２３１号公報及び特開平３−５５２３０号公報などに示されるように、フィルム長さ方向の張力を１０ｋｇ／ｍ以下に保ちながら、熱風、ラジエーションヒーターで、７０〜３００℃に加熱して１〜６０秒の時間加熱処理した後、冷却処理をして低熱収縮を行うことが望ましい。
【００４６】
かくして得られる本発明のポリイミドフィルムは、加工時に発生するしわと蛇行が改良され、銅箔を代表とする金属箔または金属薄膜が積層された電気配線板の支持体またはフレキシブル印刷回路保護用カバーレイフィルムとして好適である。
【００４７】
【実施例】
以下に、実施例を挙げて本発明をさらに説明するが、実施例における各物性の測定は、次の方法により行った。
［フイルムの熱収縮量］
ポリイミドフィルムを２００℃で１時間処理した後の熱収縮率であり、測定方法はＪＰＣＡ−ＢＭ０１−１９８８に準じた。
［フィルムの最大たるみ値］
たるみ値は、フィルムを２本の支柱ロールに掛け、異端を固定して、他端に荷重を掛けた際に生じるフィルムの幅方向（ＴＤ）の水平線からのたるみ差を、自重５ｇでスケール測定した。図１及び図２に示したＪＰＣＡ−ＢＭ０１に準拠し、荷重２ｋｇ／ｍ、ロール間距離８４ｃｍとしてその間の中央で測定した。タルミ値の測定点は幅方向に、フィルム端部から１５ｍｍを起点に５０ｍｍ間隔で測定を行い、もう一方のフィルム端部から１５ｍｍの位置までを測定した。最大タルミ値はその値の中で最大のものである。
［加工性］
フレキシブル銅張りポリイミドシートに加工する際の加工性を評価し、次の２基準で判定した。
【００４８】
○：加工中にシワ、蛇行を生じることなく安定して加工することができた
×：加工中にシワ、蛇行を生じて歩留まりが低下した。
［実施例１］
乾燥したＮ，Ｎ−ジメチルアセトアミド１９０．６Ｋｇ中に、４，４’−ジアミノジフェニールエーテル２０．００２４ｋｇ（０．１ｋｍｏｌ）を溶解し、２０℃で撹拌しながら、精製した粉末状のピロメリット酸二無水物２１．８１２ｋｇ（０．１ｋｍｏｌ）を少量ずつ添加し、１時間撹拌し続けて、透明なポリアミド酸溶液を得た。このポリアミド酸溶液に、無水酢酸をポリアミド酸単位に対して２．５ｍｏｌ、βピコリンをポリアミド酸単位に対して２．０ｍｏｌを冷却しながら混合し、ポリアミド酸有機溶媒溶液を得た。
【００４９】
このポリアミド酸の有機溶媒溶液を−１０℃に冷却して定量供給し、スリット幅１．３ｍｍ、長さ１８００ｍｍのＴダイから押し出して、９０℃の金属エンドレスベルト上に流延し、自己支持性のあるゲルフィルムを得た。
【００５０】
ゲルフィルムを金属エンドレスベルトから剥離して、６５℃の温度で、走行方向に１．３倍延伸し、次いでテンタに導入した。この場合の固形分に対する主たる揮発分の含有率は４５０％であった。
【００５１】
次いで、テンターで乾燥ゾーンの入り口まで幅方向に１．３倍延伸して、２６０℃の温度で４０秒間乾燥しながら、総横延伸倍率１．４３倍まで延伸した。引き続いて、４３０℃で１分熱処理し、冷却ゾーンでリラックスさせながら３０秒間冷却し、フィルムをエッジカットし、幅２０００ｍｍ、厚さ２５μｍのポリイミドフィルム原反を得た。この原反をスリッターにより幅１０２８ｍｍにスリットした。スリット後、張力５．０ｋｇ／ｍ、温度２８０℃でトンネル型赤外線照射炉に連続的に送り込み２０秒間熱処理をした後、炉外で巻き取りながら室温で冷却した（低熱収縮処理）。熱処理中のフィルム張力は送りローラと巻き取りローラの回転速度差で調整した。
【００５２】
このようにして得られたポリイミドフィルムに、ポリエステル／エポキシ系の接着剤をロールコータで塗布して、１６０℃でドライヤーで乾燥した。このフィルムの接着剤を塗布した面に電解銅箔を１３０℃で加圧ラミネートし、２４時間キュアーしてフレキシブル銅張りポリイミドシートを得た。加工中、シワ、蛇行なく安定して加工することができた。
【００５３】
得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に示す。
［実施例２］
乾燥したＮ，Ｎ−ジメチルアセトアミド１９０．６Ｋｇ中に、４，４’−ジアミノジフェニールエーテル１４．００２ｋｇ（０．０７ｋｍｏｌ）とパラフェニレンジアミン３．２３６ｋｇ（０．０３ｋｍｏｌ）を溶解し、２０℃で撹拌しながら、精製した粉末状のピロメリット酸二無水物２１．８１２ｋｇ（０．１ｋｍｏｌ）を少量ずつ添加し、１時間撹拌し続けて、透明なポリアミド酸溶液を得た。
【００５４】
このポリアミド酸溶液に、無水酢酸をポリアミド酸単位に対して２．５ｍｏｌ、βピコリンをポリアミド酸単位に対して２．０ｍｏｌ、それぞれ冷却しながら混合し、ポリアミド酸有機溶媒溶液を得た。このポリアミド酸の有機溶媒溶液を−１０℃に冷却、定量供給して、スリット幅は、１．３ｍｍ、長さ１８００ｍｍのＴダイから押し出して、９０℃の金属エンドレスベルト上に流延し、自己支持性のあるゲルフィルムを得た。
【００５５】
次に、ゲルフィルムを金属エンドレスベルトから剥離して、６５℃の温度で、走行方向に１．２５倍延伸し、次いでテンタに導入した。この場合の固形分に対する主たる揮発分の含有率は４２０％であった。
【００５６】
引き続き、テンターで乾燥ゾーンの入り口まで幅方向に１．１８倍延伸して、２６０℃の温度で４０秒間乾燥しながら、総横延伸倍率１．３５倍まで延伸した。
【００５７】
さらに、４３０℃で１分熱処理し、冷却ゾーンでリラックスさせながら３０秒間冷却し、フィルムをエッジカットし、幅２０００ｍｍ、厚さ２５μｍのポリイミドフィルム原反を得た。この原反をスリッターにより幅１０２８ｍｍにスリットした。スリット後、張力５．０ｋｇ／ｍ、温度２８０℃でトンネル型赤外線照射炉に連続的に送り込み、２０秒間熱処理をした後、炉外で巻き取りながら室温で冷却した（低熱収縮処理）。熱処理中のフィルム張力は送りローラと巻き取りローラの回転速度差で調整した。
【００５８】
このようにして得られたポリイミドフィルムに、ポリエステル／エポキシ系の接着剤をロールコータで塗布して、１６０℃でドライヤーで乾燥した。このフィルムの接着剤を塗布した面に電解銅箔を１３０℃で加圧ラミネートし、２４時間キュアーしてフレキシブル銅張りポリイミドシ−トを得た。加工中、シワ、蛇行なく安定して加工できた。
【００５９】
得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に併記する。
［実施例３］
乾燥したＮ，Ｎ−ジメチルアセトアミド１９０．６Ｋｇ中に、４，４’−ジアミノジフェニールエーテル２０．００２４ｋｇ（０．１ｋｍｏｌ）を溶解し、２０℃で撹拌しながら、精製した粉末状のピロメリット酸二無水物２１．８１２ｋｇ（０．１ｋｍｏｌ）を少量ずつ添加し、１時間撹拌し続けて、透明なポリアミド酸溶液を得た。このポリアミド酸溶液に、無水酢酸をポリアミド酸単位に対して２．５ｍｏｌ、ピリジンをポリアミド酸単位に対して２．０ｍｏｌを、それぞれ冷却しながら混合し、ポリアミド酸有機溶媒溶液を得た。このポリアミド酸の有機溶媒溶液を−１０℃に冷却、定量供給し、スリット幅は、１．３ｍｍ、長さ１８００ｍｍのＴダイから押し出して、９０℃の金属エンドレスベルト上に流延し、自己支持性のあるゲルフィルムを得た。
【００６０】
次いで、ゲルフィルムを金属エンドレスベルトから剥離して、６５℃の温度で、走行方向に１．４倍延伸し、引き続いてテンタに導入した。この場合の固形分に対する主たる揮発分の含有率は４２０％であった。
【００６１】
次に、テンターで乾燥ゾーンの入り口まで幅方向に１．３１倍延伸して、２６０℃の温度で４０秒間乾燥しながら、総横延伸倍率１．６０倍まで延伸した。引き続いて、４３０℃で１分熱処理し、冷却ゾーンでリラックスさせながら３０秒間冷却し、フィルムをエッジカットし、幅２０００ｍｍ、厚さ１２．５μｍのポリイミドフィルム原反を得た。この原反をスリッターにより幅１０２８ｍｍにスリットした。スリット後、張力５．０ｋｇ／ｍ、温度２３０℃でトンネル型赤外線照射炉に連続的に送り込み２０秒間熱処理をした後、炉外で巻き取りながら室温で冷却した（低熱収縮処理）。熱処理中のフィルム張力は送りローラと巻き取りローラの回転速度差で調整した。
【００６２】
このようにしてえられたポリイミドフィルムに、ポリエステル／エポキシ系の接着剤をロールコータで塗布して、１６０℃でドライヤーで乾燥した。このフィルムの接着剤を塗布した面に電解銅箔を１３０℃で加圧ラミネートし、２４時間キュアーしてフレキシブル銅張りポリイミドシ−トを得た。加工中、シワ、蛇行なく安定して加工できた。
【００６３】
得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に併記する。
［比較例１］
実施例１において、ゲルフィルムを金属エンドレスベルトから剥離して、６５℃の温度で、走行方向に１．１倍延伸し、次いでテンタに導入した。テンターで乾燥ゾーンの入り口まで幅方向に１．１倍延伸して、２６０℃の温度で４０秒間乾燥しながら、総横延伸倍率１．４５倍まで延伸した。
【００６４】
それ以外は実施例１と同様にして得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に併記する。
［比較例２］
実施例１において、６５℃の温度で、走行方向に１．１倍延伸しついでテンタに導入した。テンターで乾燥ゾーンの入り口まで幅方向に１．２倍延伸して、２６０℃の温度で４０秒間乾燥しながら、総横延伸倍率１．２７倍まで延伸した。
【００６５】
それ以外は実施例１と同様にして得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に併記する。
［比較例３］
実施例１において、スリット後トンネル型赤外線照射炉での低熱収縮処理を省略した以外は、実施例１と同様にして得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に併記する。
［比較例４］
実施例２において、１５０℃の温度で、走行方向に１．４倍延伸し、次いでテンタに導入した。固形分に対して主たる揮発分の含有率は３９０％であった。テンターで乾燥ゾーンの入り口まで幅方向に１．３１倍延伸した。
【００６６】
それ以外は実施例２と同様にして得られたポリイミドフィルムの最大タルミ値、熱収縮量及び加工性の評価結果を表１に併記する。
【００６７】
【表１】

【００６８】
【発明の効果】
以上説明したように、本発明のポリイミドフィルムは、低熱収縮処理後のたるみ量が小さく、加工時に発生するしわと蛇行が改良されたものであることから、銅箔を代表とする金属箔または金属薄膜が積層された電気配線板の支持体またはフレキシブル印刷回路保護用カバーレイフィルムとして好適である。
【００６９】
また、本発明のポリイミドフィルムの製造方法によれば、上記の特性を有するポリイミドフィルムを効率的に製造することができる。
【図面の簡単な説明】
【図１】は本発明の実施例においてフィルムの最大たるみ値を測定するために使用するＪＰＣＡ−ＢＭ０１の正面図である。
【図２】は同じく斜視図である。
【符号の説明】
１：スライドスケール
２：加重（２ｋｇ）
３：フィルム固定部[0001]
BACKGROUND OF THE INVENTION
The present invention provides a polyimide film suitable for use as an electric wiring board support or a flexible printed circuit protection cover lay film in which wrinkles and meandering generated during processing are improved and a metal foil or metal thin film represented by copper foil is laminated. And a manufacturing method thereof.
[0002]
[Prior art]
Polyimide film has high heat resistance and high electrical insulation, so it is used in a wide range of industrial fields as an electrical insulation material that requires heat resistance. Especially, a support for electrical wiring boards laminated with copper foil. For example, solder can be used to connect an electrical component such as an IC and a copper foil, and the electrical wiring can be reduced in size and weight. As a result, flexible printed circuit boards have expanded their range of use, and demand for polyimide films is growing.
[0003]
However, with the diversification of uses of electrical wiring boards and the progress of higher density of wiring, the actual situation is that the demand for improvement in performance and workability as an electrical insulating support is further increased.
[0004]
However, if the polyimide film has large talmi, wrinkles or meandering occurs during processing, and when the heat-resistant adhesive is applied to the surface of the polyimide film, application unevenness and adhesive repellency occur, resulting in a decrease in yield.
[0005]
On the other hand, a flexible circuit board with a small curl (for example, see Patent Document 1) that defines the amount of talmi and elongation of a polyimide film is known. In this case, thermal contraction of the polyimide film is defined. Therefore, there is a problem that the film shrinks and wrinkles are generated when the film is heated by laminating or the like.
[0006]
Moreover, although the polyimide film (for example, refer patent document 1) whose heat shrinkage amount in 200 degreeC is 0.05% or less is also known, since the transverse stretch of a polyimide film is not made | formed in this case, the amount of talmi There was a problem of becoming a large film.
[0007]
Furthermore, it is also known to use a polyester film with a small amount of talmi for a flexible printed circuit, but in this case, solder heat resistance is insufficient.
[0008]
[Patent Document 1]
JP-A-5-327147
[Patent Document 2]
Japanese Patent Laid-Open No. 3-552305
[0009]
[Problems to be solved by the invention]
The present invention has been achieved as a result of studying the above-described problems in the prior art as an object, and an object thereof is to provide a polyimide film with improved wrinkles and meandering generated during processing and a method for producing the same. It is.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the polyimide film of the present invention is a polyimide film in which a polyimide film having a width of 1000 mm or more and a thickness of 29 microns or less is wound on a roll 30 times or more, and has a heat shrinkage of 200 ° C. Is 0.05% or less, and the maximum tarmi value at a load of 2 kg / m is 8 to 11 m. m It is characterized by being.
[0011]
In addition, the method for producing a polyimide film of the present invention having the above-described characteristics is obtained by extruding or applying an organic solvent solution of polyamic acid onto a support to form a gel film having a volatile content or being contracted by heating. After molding, by fixing both ends of this gel film and passing through a heating furnace, the content of the main volatile content is 400% by weight with respect to the solid content in the production process of the polyimide film that is continuously dried or cured. In the above state, at a ratio of 50% or more with respect to the total stretching amount in the film width direction. side The film is stretched and then stretched laterally so that the total stretching amount is 1.3 to 1.6 times.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The polyimide film of the present invention is a polyimide film having a width of 1000 mm or more and a thickness of 29 microns or less, a heat shrinkage at 200 ° C. of 0.05% or less, and a maximum tarmi value of a load of 2 kg / m is 11 mm or less. As a result, the generation of wrinkles and meandering, which are problems in the process of processing the flexible printed circuit, is greatly reduced, and the yield can be improved.
[0013]
Here, the film tarmi referred to in the present invention is a state in which the film is not flat when the film is stretched between rolls because the length in the film transport direction differs in the width direction, It means a state where the film is stuck and sagging and is not partially flat, and the film is three-dimensional.
[0014]
In addition, although the polyimide film in this invention is provided to a process as a polyimide film roll wound up by the roll, in the polyimide film roll which has a polyimide film and a winding core, a polyimide film with a width of 500 mm or more is used for a winding core. This is intended for rolls that are wound 30 times or more. For polyimide film rolls with a width of less than 500 mm, the flow of entrained air in the film winding process Road Wrinkles are less likely to occur. Moreover, in the polyimide film roll which is less than 30 times, since air is relatively little between the film layers, wrinkles are hardly generated.
[0015]
The polyamic acid which is a precursor of the polyimide film in the present invention is composed of an aromatic tetracarboxylic acid and an aromatic diamine and is composed of a repeating unit represented by the following formula 1.
[0016]
[Chemical 1]

[0017]
In the above formula 1, R1 is a tetravalent organic group having at least one aromatic ring, the carbon number of which is 25 or less, and each of the two carboxyl groups bonded to R1 is an aromatic ring in R1. Are bonded to adjacent carbon atoms, and R2 is a divalent organic group having at least one aromatic ring, the carbon number of which is 25 or less. It is assumed that the amino group is bonded to a carbon atom of the aromatic ring in R2.
[0018]
Specific examples of the aromatic tetracarboxylic acids include pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3 ′, 3,4′-biphenyltetracarboxylic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalenedicarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5,6- Tetracarboxylic acids and their amide-forming derivatives are mentioned. In the production of polyamic acid, these acid anhydrides are preferably used.
[0019]
Specific examples of the aromatic diamines include paraphenylene diamine, metaphenylene diamine, benzidine, paraxylylene diamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, and 4,4′-diaminodiphenyl. Sulfone, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3′-dimethoxybenzidine, 1,4-bis (3methyl-5aminophenyl) benzene and their Examples include amide-forming derivatives. Among these, it is preferable to contain at least paraphenylenediamine.
[0020]
Specific examples of the organic solvent used in the present invention include organic polar amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and these organic solvents. May be used alone or in combination of two or more. Further, it may be used in combination with a non-solvent such as benzene, toluene or xylene.
[0021]
The organic solvent solution of the polyamic acid used in the present invention contains 5 to 40% by weight, preferably 10 to 30% by weight of the solid content, and the viscosity is 500 to 20000 poise as measured by a Brookfield viscometer. Preferably, the one having 1000 to 10000 poise is preferable for stable liquid feeding.
[0022]
Moreover, the polyamic acid in the organic solvent solution may be partially imidized, and may contain a small amount of an inorganic compound.
[0023]
In the present invention, the aromatic tetracarboxylic acids and the aromatic diamines are polymerized in such a proportion that their respective mole numbers are approximately equal, or one of them is within a range of 10 mol%, preferably 5 mol%, relative to the other. And may be added in excess.
[0024]
The polymerization reaction is continuously carried out in a temperature range of 0 to 80 ° C. for 10 minutes to 30 hours with stirring and / or mixing in an organic solvent. If necessary, the polymerization reaction is divided or the temperature is increased or decreased. It doesn't matter. Although there is no restriction | limiting in particular in the addition order of both reactants, It is preferable to add aromatic tetracarboxylic acid in the solution of aromatic diamines. Vacuum defoaming during the polymerization reaction is an effective method for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform a polymerization reaction by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction.
[0025]
Specific examples of the ring-closing catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylenediamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and betapicoline. It is preferable to use at least one amine selected from tertiary amines.
[0026]
Specific examples of the dehydrating agent used in the present invention include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Acetic acid and / or benzoic anhydride are preferred.
[0027]
The content of the ring closure catalyst and the dehydrating agent for the polyamic acid is represented by the following formulas
[0028]
[Expression 1]

[0029]
[Expression 2]

[0030]
It is preferable that Moreover, you may use together gelatinization retarders, such as acetylacetone.
[0031]
Below, the method to manufacture a polyimide film from the organic solvent solution of the said polyamic acid is demonstrated concretely.
[0032]
First, as a method for forming a gel film, an organic solvent solution of polyamic acid not containing a ring-closing catalyst and a dehydrating agent is cast from a slit-attached base onto a support, formed into a film, and heated and dried on the support. After the gel film has self-supporting property, it is peeled off from the support, and further imidized by drying and heat treatment at a high temperature, and a polyamic acid containing a ring-closing catalyst and a dehydrating agent. An organic solvent is cast from a base with a slit onto a support and formed into a film shape.After making a part of the imidization on the support to form a self-supporting gel film, it is peeled off from the support. A chemical ring closure method in which heat drying / imidization and heat treatment are performed is a typical method.
[0033]
In the present invention, any of the ring closure methods may be adopted, but the chemical ring closure method requires a facility containing a ring closure catalyst and a dehydrating agent in an organic solvent solution of polyamic acid, but the gel film having a self-supporting property is short. More preferable in terms of time.
[0034]
The polyamic acid contains a ring-closing catalyst and a dehydrating agent. The polyamic acid organic solvent solution, the ring-closing catalyst and the dehydrating agent are mixed in a rotary mixer, and the polyamic acid organic solvent solution is fed into a static mixer. Close just before the static mixer ring Examples thereof include a method of injecting a catalyst and a dehydrating agent, a method of casting an organic solvent solution of a polyamic acid on a support, and a method of contacting the ring-closing catalyst and the dehydrating agent. From the viewpoint of properties, a method of mixing with a mixer and feeding a mixed solution of a ring-closing catalyst, a dehydrating agent, and an organic solvent solution of polyamic acid into a slit-shaped die is preferable.
[0035]
At this time, it is necessary to adjust the solid content concentration and the temperature so that the viscosity of the mixed solution becomes 100 to 10,000 poise. This mixed solution has a property that the polyamic acid undergoes a thermal ring-closing reaction and becomes extremely high in viscosity and cannot be discharged from the die. Therefore, it needs to be kept at a low temperature (for example, −10 ° C.).
[0036]
The mixed solution is formed into a film shape through a slit-shaped base, cast on a heated support, undergoes a thermal ring-closing reaction on the support, and becomes a gel film having self-supporting support. Is peeled off. The support is a metal rotating drum or endless belt, and its temperature is controlled by a liquid or gaseous heat medium and / or by radiant heat from an electric heater or the like.
[0037]
The gel film is heated to 30 to 200 ° C., preferably 40 to 150 ° C. by receiving heat from the support and / or receiving heat from a heat source such as hot air or an electric heater, and volatilizes the free organic solvent or the like. The portion is made self-supporting by drying and then peeled off from the support.
[0038]
The gel film peeled from the support is in a state where the main volatile content is 400% by weight or more with respect to the solid content.
[0039]
This gel film is preferably stretched in the running direction while regulating the running speed with a rotating roll. Stretching is carried out at a temperature of 140 ° C. or lower at a magnification of 1.05 to 1.9 times, preferably 1.1 to 1.6 times, and more preferably 1.1 to 1.5 times.
[0040]
The gel film stretched in the running direction is introduced into a tenter device, and both ends in the width direction are gripped by the tenter clip. While running with the tenter clip, the main volatile content is 400% by weight with respect to the solid content. In the above state, the film is stretched in the width direction at a temperature of 140 ° C. or lower. Here, it is an important requirement to complete 50% or more of the total transverse stretching amount before entering the drying zone. That is, when the volatile content is less than 400% by weight, uneven stretching tends to occur, and the amount of sag deteriorates. Therefore, the width stretch ratio in the state where the volatile content is 400% by weight or more is set to the total width. It is necessary to stretch 50% or more of the draw ratio.
[0041]
Next, the gel film is introduced into the drying zone and is stretched while being dried, so that the total stretching ratio in the width direction is 1.3 times to 1.6 times. When fixing both ends of the film in this process and stretching in the width direction, conventional problems such as tearing of the film due to sudden stretching in the width direction of the film and tearing from the pin or clip part fixed at both ends of the film In order to prevent this, it was usual to make the film peeled from the support smaller than 1.3 times when the amount of the solvent in the film is 400% by weight or more. Therefore, there may be a difference in physical properties between the center and both ends in the width direction of the film.
[0042]
In the drying zone of the solvent amount, before heating with hot air, etc., install a nozzle that can exhaust the leaked air and heated air, and leak the air containing the solvent after film drying in the drying zone It is desirable to prevent mixing with air. The hot air temperature in the drying zone is preferably 200 to 300 ° C. In addition to hot air, radiant heating may be used.
[0043]
The film dried in the drying zone is heated for 15 seconds to 10 minutes with hot air, an infrared heater or the like. Next, heat treatment is performed at a temperature of 250 to 500 ° C. for 15 seconds to 20 minutes using hot air and / or an electric heater. In this case, since the planarity is lost when heated rapidly, it is necessary to select a heating method as appropriate. The heat treated film is cooled and then wound up.
[0044]
The wound original film is appropriately slit. In the polyimide film of the present invention, different polymers may be blended for the purpose of increasing the strength within the range not impairing the object of the present invention. In addition, organic additives such as antioxidants, heat stabilizers, ultraviolet absorbers, light-shielding agents, and antistatic agents may be added to the extent that they are usually added. Furthermore, the raw film may be subjected to easy adhesion treatment such as plasma treatment or corona discharge treatment.
[0045]
In order to reduce the heat shrinkage at 200 ° C., as shown in JP-A-3-55232, JP-A-3-55231 and JP-A-3-55230, the tension in the film length direction is set. While maintaining at 10 kg / m or less, it is desirable to heat to 70 to 300 ° C. with hot air or a radiation heater and heat-treat for 1 to 60 seconds, and then cool to perform low heat shrinkage.
[0046]
The polyimide film of the present invention thus obtained has improved wrinkles and meandering generated during processing, and is a support for an electric wiring board in which a metal foil or a metal thin film typified by copper foil is laminated, or a coverlay for protecting a flexible printed circuit. Suitable as a film.
[0047]
【Example】
Hereinafter, the present invention will be further described with reference to examples. The physical properties in the examples were measured by the following methods.
[Heat shrinkage of film]
It is the heat shrinkage rate after processing the polyimide film at 200 ° C. for 1 hour, and the measuring method was based on JPCA-BM01-1988.
[Maximum sag of film]
The sag value is measured by measuring the sag difference from the horizontal line in the width direction (TD) of the film when the film is hung on two strut rolls, the other end is fixed, and the other end is loaded with a weight of 5 g. did. Based on JPCA-BM01 shown in FIGS. 1 and 2, the load was 2 kg / m and the distance between rolls was 84 cm, and the measurement was performed at the center between them. The measurement points of the tarmi value were measured in the width direction at intervals of 50 mm starting from 15 mm from the film edge, and measured from the other film edge to a position of 15 mm. The maximum tarmi value is the largest of the values.
[Machinability]
The processability at the time of processing into a flexible copper-clad polyimide sheet was evaluated and judged according to the following two criteria.
[0048]
○: Stable processing was possible without wrinkling or meandering during processing.
X: Wrinkles and meandering occurred during processing, and the yield decreased.
[Example 1]
In 190.6 kg of dried N, N-dimethylacetamide, 20.0424 kg (0.1 kmol) of 4,4′-diaminodiphenyl ether was dissolved and purified at 20 ° C. while stirring, and purified into powdered pyromellitic acid 21.812 kg (0.1 kmol) of dianhydride was added little by little, and stirring was continued for 1 hour to obtain a transparent polyamic acid solution. The polyamic acid solution was mixed while cooling 2.5 mol of acetic anhydride with respect to the polyamic acid unit and 2.0 mol of β picoline with respect to the polyamic acid unit to obtain a polyamic acid organic solvent solution.
[0049]
This organic solvent solution of polyamic acid is cooled to −10 ° C., quantitatively supplied, extruded from a T-die having a slit width of 1.3 mm and a length of 1800 mm, cast on a metal endless belt at 90 ° C., and self-supporting. A gel film was obtained.
[0050]
The gel film was peeled from the metal endless belt, stretched 1.3 times in the running direction at a temperature of 65 ° C., and then introduced into a tenter. In this case, the main volatile content relative to the solid content was 450%.
[0051]
Next, the film was stretched 1.3 times in the width direction to the entrance of the drying zone with a tenter, and stretched to a total transverse stretching ratio of 1.43 times while drying at a temperature of 260 ° C. for 40 seconds. Then, it heat-processed for 1 minute at 430 degreeC, it cooled for 30 second, relaxing in a cooling zone, the film was edge-cut, and the polyimide film original fabric of width 2000mm and thickness 25micrometer was obtained. This original fabric was slit to a width of 1028 mm with a slitter. After slitting, it was continuously fed into a tunnel-type infrared irradiation furnace at a tension of 5.0 kg / m and a temperature of 280 ° C., heat treated for 20 seconds, and then cooled at room temperature while being wound outside the furnace (low heat shrinkage treatment). The film tension during the heat treatment was adjusted by the difference in rotational speed between the feed roller and the take-up roller.
[0052]
A polyester / epoxy adhesive was applied to the polyimide film thus obtained with a roll coater and dried with a dryer at 160 ° C. An electrolytic copper foil was pressure-laminated at 130 ° C. on the surface of the film on which the adhesive was applied and cured for 24 hours to obtain a flexible copper-clad polyimide sheet. During processing, stable processing was possible without wrinkles and meandering.
[0053]
Table 1 shows the evaluation results of the maximum tarmi value, heat shrinkage, and workability of the obtained polyimide film.
[Example 2]
In 190.6 kg of dried N, N-dimethylacetamide, 14.002 kg (0.07 kmol) of 4,4′-diaminodiphenyl ether and 3.236 kg (0.03 kmol) of paraphenylenediamine were dissolved at 20 ° C. While stirring, 21.812 kg (0.1 kmol) of purified powdered pyromellitic dianhydride was added little by little, and stirring was continued for 1 hour to obtain a transparent polyamic acid solution.
[0054]
To this polyamic acid solution, 2.5 mol of acetic anhydride and 2.0 mol of β-picoline relative to the polyamic acid unit were mixed while cooling to obtain a polyamic acid organic solvent solution. This polyamic acid organic solvent solution is cooled to −10 ° C., quantitatively supplied, extruded from a T-die having a slit width of 1.3 mm and a length of 1800 mm, and cast on a metal endless belt at 90 ° C. A supporting gel film was obtained.
[0055]
Next, the gel film was peeled from the metal endless belt, stretched 1.25 times in the running direction at a temperature of 65 ° C., and then introduced into a tenter. In this case, the main volatile content relative to the solid content was 420%.
[0056]
Then, it extended | stretched 1.18 time in the width direction to the entrance of the drying zone with the tenter, and extended | stretched to 1.35 times of the total transverse draw ratio, drying for 40 seconds at the temperature of 260 degreeC.
[0057]
Furthermore, it heat-processed at 430 degreeC for 1 minute, cooled for 30 second, relaxing in a cooling zone, the film was edge-cut, and the polyimide film original fabric of width 2000mm and thickness 25micrometer was obtained. This original fabric was slit to a width of 1028 mm with a slitter. After slitting, it was continuously fed into a tunnel-type infrared irradiation furnace at a tension of 5.0 kg / m and a temperature of 280 ° C., heat-treated for 20 seconds, and then cooled at room temperature while being wound outside the furnace (low heat shrinkage treatment). The film tension during the heat treatment was adjusted by the difference in rotational speed between the feed roller and the take-up roller.
[0058]
A polyester / epoxy adhesive was applied to the polyimide film thus obtained with a roll coater and dried with a dryer at 160 ° C. An electrolytic copper foil was pressure-laminated at 130 ° C. on the surface of the film where the adhesive was applied, and cured for 24 hours to obtain a flexible copper-clad polyimide sheet. During processing, it could be processed stably without wrinkles and meandering.
[0059]
Table 1 also shows the evaluation results of the maximum tarmi value, heat shrinkage, and workability of the obtained polyimide film.
[Example 3]
In 190.6 kg of dried N, N-dimethylacetamide, 20.0424 kg (0.1 kmol) of 4,4′-diaminodiphenyl ether was dissolved and purified at 20 ° C. while stirring, and purified into powdered pyromellitic acid 21.812 kg (0.1 kmol) of dianhydride was added little by little, and stirring was continued for 1 hour to obtain a transparent polyamic acid solution. To this polyamic acid solution, 2.5 mol of acetic anhydride with respect to the polyamic acid unit and 2.0 mol of pyridine with respect to the polyamic acid unit were mixed while cooling to obtain a polyamic acid organic solvent solution. This polyamic acid organic solvent solution is cooled to -10 ° C and supplied in a fixed quantity, extruded from a T-die having a slit width of 1.3 mm and a length of 1800 mm, cast onto a metal endless belt at 90 ° C, and self-supporting A characteristic gel film was obtained.
[0060]
Next, the gel film was peeled from the metal endless belt, stretched 1.4 times in the running direction at a temperature of 65 ° C., and subsequently introduced into the tenter. In this case, the main volatile content relative to the solid content was 420%.
[0061]
Next, the film was stretched 1.31 times in the width direction to the entrance of the drying zone with a tenter and stretched to a total transverse stretching ratio of 1.60 times while drying at a temperature of 260 ° C. for 40 seconds. Then, it heat-processed for 1 minute at 430 degreeC, it cooled for 30 seconds, relaxing in a cooling zone, the film was edge-cut, and the polyimide film original fabric of width 2000mm and thickness 12.5micrometer was obtained. This original fabric was slit to a width of 1028 mm with a slitter. After slitting, it was continuously fed into a tunnel-type infrared irradiation furnace at a tension of 5.0 kg / m and a temperature of 230 ° C., heat-treated for 20 seconds, and then cooled at room temperature while being wound outside the furnace (low heat shrinkage treatment). The film tension during the heat treatment was adjusted by the difference in rotational speed between the feed roller and the take-up roller.
[0062]
A polyester / epoxy adhesive was applied to the polyimide film thus obtained with a roll coater and dried with a dryer at 160 ° C. An electrolytic copper foil was pressure-laminated at 130 ° C. on the surface of the film where the adhesive was applied, and cured for 24 hours to obtain a flexible copper-clad polyimide sheet. During processing, it could be processed stably without wrinkles and meandering.
[0063]
Table 1 also shows the evaluation results of the maximum tarmi value, heat shrinkage, and workability of the obtained polyimide film.
[Comparative Example 1]
In Example 1, the gel film was peeled from the metal endless belt, stretched 1.1 times in the running direction at a temperature of 65 ° C., and then introduced into the tenter. The film was stretched 1.1 times in the width direction to the entrance of the drying zone with a tenter and stretched to a total transverse stretching ratio of 1.45 times while drying at a temperature of 260 ° C. for 40 seconds.
[0064]
Other than that, Table 1 also shows the evaluation results of the maximum talmi value, heat shrinkage, and workability of the polyimide film obtained in the same manner as in Example 1.
[Comparative Example 2]
In Example 1, the film was stretched 1.1 times in the running direction at a temperature of 65 ° C. and then introduced into the tenter. The film was stretched 1.2 times in the width direction to the entrance of the drying zone with a tenter, and stretched to a total transverse stretching ratio of 1.27 times while drying at a temperature of 260 ° C. for 40 seconds.
[0065]
Other than that, Table 1 also shows the evaluation results of the maximum talmi value, heat shrinkage, and workability of the polyimide film obtained in the same manner as in Example 1.
[Comparative Example 3]
In Example 1, except for omitting the low heat shrinkage treatment in the tunnel-type infrared irradiation furnace after slitting, the evaluation results of the maximum talmi value, the amount of heat shrinkage, and the workability of the polyimide film obtained in the same manner as in Example 1 are shown. This is also shown in Table 1.
[Comparative Example 4]
In Example 2, the film was stretched 1.4 times in the running direction at a temperature of 150 ° C., and then introduced into a tenter. The main volatile content relative to the solid content was 390%. The film was stretched 1.31 times in the width direction to the entrance of the drying zone with a tenter.
[0066]
Other than that, the evaluation results of the maximum talmi value, heat shrinkage and workability of the polyimide film obtained in the same manner as in Example 2 are also shown in Table 1.
[0067]
[Table 1]

[0068]
【The invention's effect】
As described above, the polyimide film of the present invention has a small amount of sag after the low heat shrinkage treatment and improved wrinkles and meandering generated during processing. It is suitable as a support for an electric wiring board laminated with a thin film or a coverlay film for protecting a flexible printed circuit.
[0069]
Moreover, according to the manufacturing method of the polyimide film of this invention, the polyimide film which has said characteristic can be manufactured efficiently.
[Brief description of the drawings]
FIG. 1 is a front view of JPCA-BM01 used for measuring the maximum sag of a film in an embodiment of the present invention.
FIG. 2 is a perspective view of the same.
[Explanation of symbols]
1: Slide scale
2: Weighted (2kg)
3: Film fixing part

Claims (3)

A polyimide film having a width of 1000 mm or more and a thickness of 29 microns or less wound on a roll 30 times or more, and a thermal shrinkage at 200 ° C. of 0.05% or less and a maximum tarmi value with a load of 2 kg / m Is a polyimide film characterized by being 8-11 mm .   By extruding or applying an organic solvent solution of polyamic acid onto a support, the gel film is formed into a gel film having a volatile content or contracting by heating, and then both ends of the gel film are fixed and passed through a heating furnace. In the polyimide film manufacturing process in which drying or curing is continuously performed, the content of the main volatile component with respect to the solid content is 50% by weight or more with respect to the total stretching amount in the film width direction. 2. The method for producing a polyimide film according to claim 1, wherein the film is stretched transversely at the above ratio and then stretched so that the total stretched amount is 1.3 to 1.6 times.   The film obtained by transverse stretching was heated to 70 to 300 ° C. with hot air or a radiation heater while maintaining the tension in the film length direction at 10 kg / m or less, and then heat-treated for 1 to 60 seconds, The method for producing a polyimide film according to claim 2, wherein a cooling treatment is performed.

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