JP3947991B2 - Endless tubular film and its use - Google Patents

Description

（但し数式１中、Ｖａはポリマ液Ａの粘度、ｒは成型ドラムの内半径、ωは成型ドラムの角速度を示す）
そして請求項２の発明は回転する成型ドラム中で、無機添加剤添加のポリマ液Ｂを、下記数式２の条件下で無端管状に成型し、加熱乾燥してなる無端管状フイルムを特徴とするものである。
（数式２）

（但し数式２中、Ｖｂはポリマ液Ｂの粘度、ｒは成型ドラムの内半径、ωは成型ドラムの角速度をを示す）
尚、請求項３〜６は前記請求項１又は２に従属し、好ましい態様としての発明であり、そして請求項７は、請求項６に従属して得られた無端管状フイルムをカラー複写機の中間転写用ベルトとして使用する発明である。本発明を次の実施形態で詳細に説明する。
【０００５】
【発明の実施の形態】
請求項１の発明から説明する。
まずここで成型の対象となる無機添加剤無添加のポリマ液Ａは、主として熱可塑性又は熱硬化性の樹脂を（マトリツクス）ポリマとし、これが少なくとも無機添加剤は含有されずに、所定の液粘度を以て液体をなしているものである。液体はそのポリマを有機溶媒で溶解して得たポリマ溶液の場合もあれば、そのポリマ自身が常態で液状を呈し、敢えて有機溶媒は使わない場合もある。ここで後者の場合は、熱可塑性又は熱硬化性に係わらず、一般にポリマが常温で液状を示す低分子のプリポリマである場合に見られる。但し熱硬化性例えば熱硬化性ポリイミドに見られように、そのプリポリマ（前駆体）が常態で固形である場合には、その有機溶媒をもって溶液となし、これを成型対象とすることになる。
【０００６】
前記ポリマ中熱可塑性樹脂は、有機溶媒に可溶であれば特に本発明に適しないといったものはない。例えば半合成セルロ−ズ、各種ポリエステル、各種ポリアミド（脂肪族、芳香族）、各種フッ素系樹脂、各種オレフイン系ポリマ（直鎖、環状）、各種ビニル系ポリマ、ポリアミドイミド、熱可塑性ポリイミド等が挙げられる。
一方熱硬化性樹脂は、一般にその樹脂自身では有機溶媒に溶解するものがないのでそのプリポリマ、つまり未硬化で常温で液状を呈している低分子レベルのものであり、エステル系、エポキシ系、フエノ−ル系、ウレタン系、シリコ−ン系に代表される。これらはこの低分子レベルのものでまず無端管状に成型し、後の加熱乾燥で高分子化することになる。
又、熱硬化性ポリイミドもあるが、これは前記するように前記の低分子レベルのプリポリマとは異なり、既に高分子のポリマである。しかしこれ自身は有機溶媒に不溶であり、その前駆体のポリアミド酸が溶解するので、これを有機溶媒に溶解したものが対象となる。
尚、前記熱可塑性樹脂の中特に各種ビニル系ポリマにあってその中で、適当な有機溶媒のないものにとっては、このプリポリマを対象とすることができる。
【０００７】
前記のポリマ液Ａを用いて、その特性に適して本発明に言う高品質・性能の無端管状フイルムが成型されるが、中でも極めて高い機能（耐熱性、耐薬品性、機械的物性）を基本特性として求める場合は、例えば芳香族ポリアミド、ポリアミドイミド、ポリイミドのいずれかが選ばれる。
【０００８】
前記ポリマ液Ａが決まれば、まずこれを回転する成型ドラム中（内面全周）に供給し、前記の数式１条件下で無端管状のフイルムに成型する。
【０００９】
前記数式１は、前記課題特に得られる無端管状フイルムの特に幅方向の厚みムラ（平面性）（うねり度合い）を解決するために、あらゆる角度から検討し遂に見出した実験式である。従って、このような実験式に従えば、どの様にして該厚みムラが解決されのか、その因果関係はよく判らない。
【００１０】
前記数式１において、Ｖａはポリマ液Ａの粘度で単位はＰａ・ｓ（パスカル秒）である。ここで粘度は温度によって異なるが、特別（ある程度加熱しないと液状を呈しない場合）でない限り常温（２０〜２５°C）での液粘度である。ｒは成型ドラムの内半径で単位はｍ、そしてω^２は成型ドラムの角速度ωの二乗で、単位はｒａｄ／ｓ（ラジアン毎秒）である。以後、式そのものを便宜上成型指標Ｆａと呼ぶことにする。
尚、角速度は（２π）×（成型ドラムの回転数ｒｐｍ）を６０秒で除したものでもあるる。
【００１１】
前記成型指標Ｆａが２．５以下、好ましくは２．２以下、更に好ましくは１．９以下になるように各条件因子が選ばれる。この数値以下にすることで、成型ドラムが回転しても実質的に遠心力となって作用しないことになり、この遠心力無作用下でのみ本発明の前記課題
（効果）が達成されることになる。該Ｆａの下限については、どのような低速度でも成型ドラムは回転していることが前提になっているので、０であってはならない。これはまず極めて低角速度でも回転しながら所望する無端管状フイルムに成型し、そして成型後の加熱乾燥を効率的に且つ均一に行う必要があるからでもある。
【００１２】
前記Ｆａを構成する各因子は、基本的にはポリマＡ液粘度Ｖａが決まれば他の該因子は若干の条件検討で自ずから決まるが、参考までに、目安とする各因子の数字的範囲を例示しておく。まず該Ｖａは０．２〜１０程度、好ましくは０．５〜７Ｐａ・ｓ。ポリマ液Ａの有する比重は１よりも大きく、１．３程度以下。ｒは０．１〜０．５ｍ程度。ωは０．３〜１０程度、好ましくは０．５〜７、更に好ましくは０．８〜５ｒａｄ／ｓである。
【００１３】
前記無端管状フイルムの製造は、工程的にはまずポリマＡ液を（前記成型指標Ｆａの条件下で）回転する成型ドラム内で無端管状に成型し、その後これを加熱乾燥するという２工程からなるが、ここで特に重要なのは前工程の成型である。これはこの工程で実質的に、本発明にいう優れた幅方向の平面度を持った高精度の無端管状フイルムに成型してしまうことが好ましいからである。
そこでこの前工程での作用効果を有効に発現するために、具体的に次のような手段を併用した成型が好ましい。
【００１４】
その手段は、前記Ｆａの条件下で成型ドラムを回転しつつポリマＡ液を別設のノズルから強制的に該ドラム内面に均一に塗布する如く吐出する方法である。更に該方法は、吐出されるＡ液の状態、つまり液状で吐出するか、噴霧状で吐出するかである。いずれの状態で吐出するかは、該Ａ液の粘度Ｖａによって使い分けるのがよいが、しかし次のうような理由から後者がより好ましい。
つまり液状吐出では、液粘度Ｖａに依存してこれが低くなる程、該Ｆａの条件下での成型ができなくなる傾向があるからである。これは液状吐出そのものが、低Ｖａになればなる程均一に吐出し難くなり、その結果これの調整のためにより高い角速度で回転しようとする。すると最早や該Ｆａの条件下で成型できなくなるといったことにる。
ところが噴霧吐出では、それ自身が液粘度Ｖａに依存することなく、より高Ｖａでも全内面均一に塗布されるように吐出できるので、敢えて更なる均一流延が行われるような該角速度で回転しなくとも、極低角速度（例えば０．３ｒａｄ／ｓ程度）の下でも効率良く目的とする無端管状フイルムに成型することができるからである。
【００１５】
尚、前記ノズルを中心とする機構は、概ね次のようなものが例示できる。
ノズルは所定幅のスリットノズルとし、左右に揺動すると共に成型ドラムの内面との距離が自由に変えられる機構をもってなる。そして回転速度と連動して所定幅だけ左又は右方向に水平移動するような機構にもなっている。また液状吐出では、吐出量を制御しつつ単に所定サイズのノズルから吐出すれば良いので供給源は圧空又はギヤポンプである。しかし噴霧吐出では、噴霧状にする必要がある。その為に該ノズルは中央部分にポリマＡ液の供給ノズルを、そして該ノズルを両サイドから挟む状態で圧空供給ノズルが設けられてなる２重構造のノズルが使われる。
【００１６】
前記成型指標Ｆａ条件下で無端管状フイルム状に成型されたならば、引続きこの条件を維持しつつ、少なくとも形状維持できる無端管状フイルムに至るまで加熱乾燥する。ここで加熱乾燥は、前記有機溶媒に溶解されたポリマを原料とする場合は、主として該溶媒を蒸発し乾燥するものであり、そして該溶媒を含まない低分子量のプリポリマを原料とする場合には、これを重合しポリマに変えつつ該フイルムに成型するためのものである。従って加熱乾燥の条件は、前者の場合では少なくとも該溶媒の沸点以上の温度、後者では重合温度以上の温度で、時間は設定温度等によって変わる。
尚、この初期の加熱乾燥の目的を達し、更に加熱乾燥を続行したい場合には、引続き成型ドラムを回転（その速度は該成型指標Ｆａ条件下での角速度でも良いし、これよりも速くても良い）しつつこれを行っても良いし、一旦該ドラムから剥離して別工程を組んで行っても良い。特に有機溶媒を使うポリマＡ液の場合及び該ポリマが前記するポリアミド酸である場合には、後者の別工程を取り入れた加熱乾燥が望ましい。これはより高い温度で残存する微量の該溶媒を完全に効率よく除去するためと、該ポリアミド酸では最終的に行うイミド化を行うのに好ましいことによる。該別工程は、剥離した該フイルムを単に熱風乾燥機に入れて加熱しても良いが、同径の円筒状金型を使ってこれに一旦嵌挿し、これを熱風乾燥機に入れて加熱するのが良い（寸法精度等にも狂いがでない）。
【００１７】
又回転する成型ドラムは、概ね次のような機構をもって成る成型装置である。まず内面鏡面仕上げされ、両内円周端部に液モレ防止用のバリヤ（必ずしも必要でない）を設けた両サイド開口の金属製中管を成型ドラムとし、これが回転するロ−ラ上に載置されている。そして該ドラムの外側上面には遠赤外線ヒ−タ、該ロ−ラには該ヒ−タ等を内設して該ドラム内を加熱するようにしている。そしてポリマ液Ａを供給するための前記いずれかの供給ノズルと、蒸発する有機溶媒を積極的に系外に除去するための給排用ノズルとが該ドラムの内部に挿脱自在機構をもって設けられている。該ドラムは該ロ−ラの回転により間接回転する。
【００１８】
次に請求項２に関し説明する。
ここでは請求項１におけるポリマＡ液に無機添加剤が含有されてなるポリマＢ液を用いて、数式２の条件下で同様に成型、加熱乾燥して無機添加剤入り無端管状フイルムとなすものである。
【００１９】
まず添加剤として特に無機物（単体又は化合物）が対象とされるのは、前記するように遠心成型法によって成型する無端管状フイルムでは、該無機物の分散が偏在し均一にならず、それによる種々の弊害が生じ易い。これは一般に該無機物自身がポリマ、有機溶媒との親和性がないことと、比重が大きいことが遠心力と言う力学的作用によってより一層助長されるためと考えられる。本発明は特にこの問題を解決することを主目的とすることがその理由である。従って本発明の手段が該添加剤以外の添加剤、例えば有機添加剤に適用されてもその効果はないか、あったとしても小さいということであって適用できないということでもない。
【００２０】
数式２において、該式そのものを便宜上成型指標Ｆｂと呼ぶが、このＦｂは数式１条件下で成型される無端管状フイルムの幅方向の平面ムラ（うねり）解消と共に、前記無機添加剤含有による偏在分散を解消すべく種々検討した結果、遂に見出された実験式で、これで求められた数値が、請求項１のそれと同じ２．５以下と言うことである。Ｆｂは無機添加剤が含有されたことで、その分具体的実施での数値設定は変わることもあるが、Ｆａと実質的に同じ枠内で同様に行えるものである。
尚、該Ｆｂ中（無機添加剤の比重）は真比重であり、見かけ比重ではない。また前記成型指標Ｆａでは、（ポリマ液Ａの比重）に比例する形であるが、該Ｆｂでは無機添加剤の比重に比例する形をとっている。これは無機添加剤が使用された場合には、該ポリマ液Ａの比重よりも遥かに大きいために、これによる影響が大きく該ポリマ液Ａの比重による影響は実質的にないことによる。
【００２１】
前記無機添加剤の比重については、ポリマＡ液自身の比重との差が大きければ大きい程、本発明に言う前記効果が大きく現れるが、あまりにも大きいと成型操作に至るまでに沈降分離する危険性が大きい。かかる観点から数値的には１．３〜５程度、望ましくは１．５〜４が例示できる。
【００２２】
そして前記添加剤は、一般に種々の目的でプラスチツクに混合し使用されているものであり特に制限はない。例えば代表的な例として難燃化はＣａ（ＯＨ）_２、機械的強度改良は９Ａｌ_２Ｏ_３・２Ｂ_２Ｏ_３、熱伝導性はＢＮ、圧電性はＢａＴｉＯ_３、光散乱・反射性はＴｉＯ_２、摺動性はＭｏＳ_２、半導電性は導電性カ−ボンブラツクが挙げられる。勿論この添加剤は、数μｍ程度以下といった微粉末体であり、具体的にどのような大きさが良いかは予備実験により決めればよい。又添加量も本来のポリマの物性を維持しつつ、その機能が付与されるように予備実験により決めればよい。
【００２３】
ポリマＢ液の調製法は、一般的には予め所定量のポリマを所定量の有機溶媒に溶解しておき、この中に所定量の無機添加剤を攪拌しながら徐々に添加し、最後にボ−ルミル等によって十分に混合・分散する。この混合の際に例えば界面活性剤を添加し分散性をよくするような場合もある。
【００２４】
次により高い耐熱性、機械的物性等を有するポリアミドイミド（以下ＰＡＩ）、ポリイミド（以下ＰＩ）をポリマとして、これに無機添加剤として導電性カ−ボンブラツク（以下単にＣＢ）を添加、混合して得たポリマＢ液を使って、前記成型指標Ｆｂの条件下で回転成型し加熱乾燥して、半導電性の付与された無端管状フイルムを製造することについてより詳細に説明しておく。
【００２５】
まず前記ＰＡＩは、一般に知られているように有機トリカルボン酸１無水物と有機ジアミンとの当モル量をジメチルアセトアミド、ジメチルフオルムアミド、ジメチルスルホオキシド、Ｎーメチルピロリドン等の非プロトン性の極性の有機溶媒中で重縮合反応することで得る。この時の反応温度を常温以下とすればＰＡＩのポリアミド酸溶液、常温以上の加熱下であればイミド化まで進んで一挙にＰＡＩ溶液を得ることかできる。一般的にはＰＡＩの場合は、それ自身該溶媒に溶解するのでＰＡＩ溶液で得るのがよい。具体的に有機トリカルボン酸１無水物として例えばトリメリット酸１無水物、有機ジアミンとして例えば３、３′―ジアミノベンゾフエノン、Ｐ―フエニレンジアミン、４、４′―ジアミノジフエニル、４、４′―ジアミノジフエニルメタン、４、４′―ジアミノジフエニルエーテル、ビス［４―｛３―（４―アミノフエノキシ）ベンゾイル｝フエニル］エーテル、４、４′―ビス（３―アミノフエノキシ）ビフエニル、ビス［４―（３―アミノフエノキシ）フエニル］スルホン、２、２′―ビス［４―（３―アミノフエノキシ）フエニル］プロパン等である。勿論該ジアミンは一種に限らず、２〜３種を使って共重合することでも良い。
尚、前記有機ジアミン中−Ｏ−、−ＳＯ2―、―ＣＯ−、アルキレン基を有するものは、得られるＰＡＩ自身の溶解性はより高くなる傾向がある。
【００２６】
一方ＰＩは有機テトラカルボン酸２無水物と有機ジアミンとの当モル量を前記の非プロトン性の極性有機溶媒中で重縮合反応することで得るが、この場合も反応温度を常温以下とすればＰＩのポリアミド酸溶液が、常温以上の加熱下ではイミド化も進みＰＩ溶液として得られる。しかしここで熱硬化性ＰＩの場合は、イミド化の進行と共に該溶媒に溶解しなくなるので、常温以下の低温で反応してポリアミド酸の段階で停止する必要がある。
具体的に有機テトラカルボン酸２無水物としては、例えばピロメリット酸２無水物、２、２′、３、３′―ビフェニルテトラカルボン酸２無水物、３、３′、４、４′―ベンゾフェノンテトラカルボン酸２無水物、ビス（２、３―ジカルボキシフェニル）メタン２無水物等。有機ジアミンとしては前記ＰＡＩで例示する芳香族ジアミンが例示できる。勿論以上の出発原料は各１種に限らず、２〜３種を混合し共縮重合反応して得たものでも良い。
このＰＩの場合も同様に原料の選択によって、得られるポリマ主鎖中に２〜３個の−Ｏ−、−ＳＯ2―、―ＣＯ−、アルキレン基（Ｃ_２以上）等を有しているものは、ＰＩ自身が前記溶媒に溶解し、熱可塑性を有する。従ってかかる原料の組合せで重縮合反応する場合には、常温より高い温度で反応し一挙にＰＩ溶液の形で得るのがよい。
尚、以上により得られる各ポリマ液は、請求項１のポリマＡ液の例示でもある。
【００２７】
又前記ＰＡＩにしてもＰＩにしても、これらが適宜ブレンドされたものをポリマＡ又はＢとしても良い。更にＰＡＩの前記酸成分とＰＩの前記酸成分とを適宜混合し、これを酸成分として前記有機ジアミンとを同様に重縮合反応して得たものをポリマＡ又はＢとしても良い。
【００２８】
そしてＣＢは、本質的にはそれ自身が導電性（例えば１０^１Ω・ｃｍ以下）を有している粉体であればその他の条件的制限はない。つまりその製造法とか、ストラクチヤ−とか、揮発分とか、ＤＢＰ吸油量、比表面積とかと言ったような一般に知られている諸特性（値）には影響されないと言うことである。このことも従来技術（種々の特性値を条件としたＣＢを特徴とする特許出願が多い）にはない特長の１つと言える。
【００２９】
前記ＣＢ粉体は、必要とする（つまり用途）半導電性（１０^２〜１０^１３Ω・ｃｍ程度又は１０^２〜１０^１３Ω／□程度の範囲）に対して、それ相応の量が前記ポリマ液Ａに添加され十分なる混合分散をもってポリマ液Ｂとされる。その相応の混合量は、ポリマ（固形分）に対して５〜２５重量％程度であり、予備的混合の後ボ−ルミル等にて十分に混合し分散して完了する。
尚、得られるポリマ液Ｂは、ＣＢ粉体に限らず他の無機添加剤も同様に長時間保存では、該添加剤が徐々に分離して来るような場合があるので、調製後はそうならない間に早く成型に供した方がよい。
【００３０】
そして前記得られたＰＡＩ溶液、（熱可塑）ＰＩ溶液又は（熱硬化ＰＩ）のポリアミド酸溶液は、前記請求項１で説明したいずれかの方法で、（Ｆｂ＝２．５以下の下）極低角速度で回転する成型ドラム内に供給し無端管状フイルム状に成型するが、外部からの本格的加熱乾燥は内面全体に塗布されてからスタ−トする。ここでの加熱温度は、特に該ポリアミド酸溶液の場合には、使用した有機極性溶媒の沸点よりも１０°C程度高く２００°C以下で行うのがよい。これは２００°C以上では成型ドラム内でイミド化反応も進行し、気泡等が内在し易く好ましくないからである。該ＰＡＩ溶液、ＰＩ溶液にしても、成型ドラム内で該溶媒の全部が蒸発除去されるまで加熱乾燥するよりも、ある程度残した（例えば５〜３０％程度）状態で停止し一旦剥離し取り出して、前記する別工程で改めて加熱乾燥する方法をとるのがよい。これも微量残存する該溶媒をより迅速に除去し、気泡内在の危険性をなくすためでもある。
尚該ポリアミド酸では、この別工程での加熱温度は常温〜４５０°C程度の間で、徐々に加熱昇温し最後に４５０°C程度に至らしめるのがよい。勿論ＰＡＩ溶液、ＰＩ溶液の場合でも全てがイミド化していない場合もあるので、かかる場合には２００°C以上の温度に加熱してミド化も完結させる必要がある。
【００３１】
尚、成型指標ＦｂにおけるポリマＢ液粘度Ｖｂ、成型ドラムの内半径、角速度ωそして成型手段については、（条件設定に若干の差はあるが）前記請求項１で縷々説明した範囲内で行われるので違いはない。
【００３２】
以上に説明した手段で製造されてなる無端管状フイルムは、次のような特性を有している。
尚、該フイルムの厚さは、使い方等によって異なるが、一般的には０．０３〜０．３ｍｍ程度である。勿論本発明がこれ以上の厚いものには適用できないということである。
まずどのような幅をとってみても、うねり等による厚みムラが極めて小さく（幅方向平面性に優れる）、例えば数値的には２ｍｍ以内、更には１．５ｍｍ以内にある。勿論縦方向（回転方向）は１ｍｍ以内で問題はない。前記成型指標Ｆａ（Ｆｂ）の２．５を超える条件（つまり遠心力下）で成型される無端管状フイルムは、特に幅方向に大きな平面ムラ（うねり）があり、これは例えばこれを物品の搬送用ベルトとして使用する場合、蛇行の原因になること、そしてまた該ベルトの表面に接しつつロ−ラを回転するような使い方の場合には、接触圧に大きなムラがあって使用できなくなる等の致命的欠陥となる。従ってベルトとして、特に幅方向の平面精度は必要不可避の条件と言える。
【００３３】
そしてまた無機添加剤含有の無端管状フイルムでは、その分散が偏在するようなことはなく極めて均一である。これは多くの該添加剤が含まれていても、該フイルム自身の機械的物性をそのまま維持し、新たな機能の付加されたものでもある。例えば前記ＣＢ含有の無端管状フイルムは前記平面度を維持し、付与される電気抵抗特性が極めて優れたものになっている。例えば体積抵抗値と表面抵抗値との差が極めて小さく、一桁以下、０．５桁以下にもなっている。前記遠心力下で得られるものでは、両者に大きな差があるが、これは明らかに分散状態の差からくるものと言える。この抵抗値に差のないことは、例えば除電又は帯電における印加電圧に依存性がないことと、経時変化がないものと言うことになる。
尚、前記遠心力下で得られる無端管状フイルムは、その位置によって電気抵抗値にバラツキがでやすいが、本発明ではそれもない。
【００３４】
更に無端管状フイルムは、その内直径がより大きくなっても（例えば１ｍ）、幅方向の平面度は勿論、全体の厚み精度に変化なく高精度を維持している。これは一般に遠心力下での成型では、その内直径がより大きくなる程、厚み精度は悪くなり、その径には限度がある。これは成型ドラムの直径アツプと共に、回転による芯ブレがあることと、該ドラム製作において高精度でもって製作することが困難であることによる。本発明では、どのような大きさの成型ドラムでも回転によって芯ブレはなく、又該ドラムの製作精度が少々悪くてもそれによる該フイルムへの影響も僅少で問題にならない。
【００３５】
本発明による前記無端管状フイルムは、前記のような優れた特性から種々の用途に使用されるが、中でもポリマとしてＰＡＩ、熱可塑ＰＩ又は熱硬化ＰＩを使い、これにＣＢ粉体を混合し電気抵抗性を付与した該フイルムは、カラ−複写機の中間転写用ベルト
として有効である。該ベルトの中でも熱硬化ＰＩでのベルトはより有効である。これは加熱定着兼転写用中間ベルトとしての使用もできるからである。
【００３６】
【実施例】
以下に比較例と共に、実施例によってさらに詳述する。
尚、本例中幅方向の平面度、体積抵抗値（Ｒｖ）と表面抵抗値（Ｒｓ）は次のようにして測定した値である。
◎幅方向の平面度・・所定幅にカットした無端管状フイルムを、直径３０ｍｍの２本のロ−ラに３５Ｎの張力で張架した状態で、キ−エンス株式会社製のレ−ザ変位計（タイプＬＫ０８０）で幅方向にレ−ザ光を照射し、該フイルム面と該レ−ザ光との距離を自動記録する。記録デ−タから山（Ｍａｘ値）と谷（Ｍｉｎ値）（うねり）を読み取り両者の差を測定値とする。
◎ＲｖとＲｓ・・三菱化学株式会社製の抵抗測定器“ハイレスタ・ＨＲブロ−ブ”を使って、１００Ｖ電圧印加の下、３０秒に直接測定した値。
【００３７】
（実施例１）（請求項１対応）
まずピロメリット酸２無水物と４、４′−ジアミノジフェニルエ−テルとの当モル量をＮ−メチルピロリドン溶媒中、２０°Cで重縮合反応して固形分濃度１８重量％の芳香族ポリアミド酸溶液（以下ＰＡ液１と呼ぶ）１０ｋｇを得た。このものの粘度は４．２Ｐａ・ｓで，比重は１．１２であった。
【００３８】
そして前記ＰＡ液１の一部を使って、次の条件で熱硬化性ＰＩの無端管状フイルムを成型した。
尚、ここで使用した成型装置は本文中（段落００１８）に記載する機構をもってなる。
内面クロムメツキ仕上げされた内径２７０×幅５００ｍｍの成型ドラムを内部に熱源（熱湯）を有する２本の回転ロ−ラ上に載置し、まず常温で６ｒａｄ／ｓの角速度でゆっくりと回転をスタ−トした。そして該ＰＡ液１を左右動する幅５０ｍｍのスリットノズルから２．５ｋｇ／ｃｍ^２の圧力で該ドラム内面に向かって噴射を開始した。該ノズルは回転に同調して右から左に移動し、所定塗布厚になったら噴射を停止した。そして引続き同角速度を維持しつつ、遠赤外線ヒ−タでの加熱を開始し約１７°C／分の昇温速度で加熱し、１５０°Cに到達した時点で昇温動作を停止し更に６０分間加熱した。この加熱の間は、吸排ノズルを使って蒸発する溶媒を積極的に系外に排出除去した。最後に加熱を停止し常温に冷却されたら、回転を停止して該ドラムから成型体を剥離した。
尚、該成型体は無端管状のポリアミド酸フイルムである。
【００３９】
そして前記得られた成型体を、外径２６５ｍｍ、幅５５０ｍｍの中空円筒金属金型（表面はＲ_Ｚ＝５．０μｍに研磨）に嵌挿してこの全体を熱風乾燥機に投入して加熱した。加熱条件は、まず１２０分間を要して３２０°C間で徐々に昇温し、引続き該温度で６０分間加熱した。最後に該乾燥機から取り出し常温にまで冷却したら該金型から外した。かくして製造された熱硬化ＰＩ無端管状フイルムの厚さは６９．５μｍであり、そして成型指標Ｆａに対する幅方向平面度は表１にまとめた。
【００４０】
（表１）

【００４１】
（実施例２）（請求項２に対応）
実施例１で得たＰＡ液１から２ｋｇを採取し、これに攪拌しながらＮ−メチルピロリドンを添加し固形分が１７重量％になるように希釈溶解した。そしてこの溶液の２ｋｇを採ってデゾルバ−に入れ、攪拌しながら１０^−１Ω・ｃｍのＣＢ粉体（真比重１．７５）
５０ｇ（固形分に対して１２．８重量％）を徐々に添加して予備混合した後、これをボ−ルミルに移し換えてミル混合し十分に分散し成型用液とした。このものの粘度は４．３Ｐａ・ｓであった。
【００４２】
そして前記成型用液を使って、実施例１と同様条件で、まずポリアミド酸の無端管状フイルムに成型し、これを成型ドラムから取出して中空円筒金属金型に嵌挿して熱風乾燥して、残存する溶媒の完全除去と共にイミド化し、厚さ７０μｍの熱硬化性ポリイミド無端管状フイルムを得た。但し、角速度は５ｒａｄ／ｓ、噴射圧力は２．０ｋｇ／ｃｍ^２であった。
【００４３】
そして前記得た熱硬化性ポリイミド無端管状フイルムの成型指標Ｆｂに対する幅方向平面度と電気抵抗値とを測定しこれを表１にまとめた。
【００４４】
（実施例３）（請求項２に対応−熱可塑ＰＩをマトリックス樹脂とする場合）
３、３′、４、４′―ベンゾフェノンテトラカルボン酸２無水物とビス［４−｛３−（４−アミノフエノキシ）ベンゾイル｝フエニル］エ−テルとの当モル量をジメチルアセトアミド溶媒中で、３５°Cで重縮合反応して固形分濃度１４重量％の溶液５ｋｇを得た。この１部を採取してＩＲ分析したところ、実質的にイミド結合に由来する吸収のみで、アミド結合に由来する吸収は確認されなかった（以下熱可塑ＰＩ液３と呼ぶ）。該液の粘度は２．５Ｐａ・ｓで，比重は１．０６であった。
【００４５】
そして前記熱可塑ＰＩ液３の１ｋｇを採取し、これをデゾルバ−に入れ攪拌しながら、９Ａｌ_２Ｏ_３・２Ｂ_２Ｏ_３（ホウ酸アルミ）（真比重３．０）（長さ０．５〜１．０μｍ−径５〜１０μｍのウイスカ）８ｇ（固形分に対して約５．４重量％）を徐々に添加して予備混合した後、これをボ−ルミルに移し換えてミル混合し十分に分散して成型用液とした。このものの粘度は２．８Ｐａ・ｓであった。
【００４６】
そして前記成型用液を使って、実施例１の成型装置で同じ手順で次の条件でまず成型ドラム内で成型した。
つまり角速度３ｒａｄ／ｓで成型ドラムの回転しつつ、噴射圧力１．５ｋｇ／ｃｍ^２で噴射後、同速度を維持しつつ加熱を開始し８０分を要して１７０°Cまで昇温した後、この状態で引続き６０間加熱した。そして常温に冷却したら回転を停止し剥離して取り出し、次ぎにこれを中空円筒金属金型に嵌挿して熱風乾燥機に入れて、２６０°Cで６０分間加熱したら常温にまで冷却し嵌脱して、相当する強化された厚さ１００μｍの熱可塑性ＰＩの無端管状フイルムを得た。
【００４７】
前記得られた無端管状フイルムの幅方向平面度と耐屈曲性を測定し表１にまとめた。
尚、耐屈曲性は該フイルムを角度１３５度で折曲げて亀裂が入った時点での折曲げ回数とした。
【００４８】
（実施例４）（請求項２に対応−ＰＡＩをマトリックス樹脂とする場合）
トリメリット酸１無水物と４、４′−ジアミノジフェニルメタンとの当モル量を、Ｎ−メチルピロリドン溶媒中、３０°Cで重縮合反応して固形分濃度２９重量％の芳香族ＰＡＩ溶液５ｋｇを得た。
尚、該溶液の１部を採ってＩＲ分析したところ、未閉環のアミド酸に基づく吸収は認められず、一方のカルボキシル基とアミノ基との重縮合に基づくアミド基と、一方のアミド酸の重縮合と共に閉環縮合したイミド基に基づく吸収であった。
【００４９】
そして前記ＰＡＩ溶液から２ｋｇを採取しこれをデゾルバ−に入れ、攪拌しながら１０^−１Ω・ｃｍのＣＢ粉体（真比重１．８２）を９６ｇ（固形分に対して１４．２重量％）を徐々に添加して予備混合した後、これをボ−ルミルに移し換えてミル混合し十分に分散し成型用液とした。このものの粘度は５．４Ｐａ・ｓであった。
【００５０】
そして前記成型用液を使って、実施例１の成型装置で同じ手順で次の条件でまず成型ドラム内で成型した。
つまり成型ドラムとして内径７００ｍｍ、幅７５０ｍｍのものを使い、角速度４ｒａｄ／ｓで該ドラムを回転しつつ、噴射圧力２．０ｋｇ／ｃｍ^２で噴射後、同速度を維持しつつ加熱を開始し９０分を要して１６０°Cまで昇温した後、この状態で引続き６０間加熱した。そして常温に冷却したら回転を停止し剥離して取り出し、次にこれを中空円筒金属金型に嵌挿して熱風乾燥機に入れて、２１０°Cで５０分間加熱したら常温に冷却して嵌脱して、相当する厚さ９０μｍのＰＡＩ無端管状フイルムを得た。
【００５１】
そして前記得たＰＡＩ無端管状フイルムの成型指標Ｆｂに対する幅方向平面度と電気抵抗値を測定し表１にまとめた。
【００５２】
（比較例１）（実施例１との比較）
実施例１で得たＰＡ液１を用いて、成型ドラムの角加速度を１０ｒａｄ／ｓとする以外は同一条件にて成型し、熱風乾燥して厚さ７１μｍの熱硬化ＰＩ無端管状フイルムを得た。得られた該フイルムの成型指標Ｆａに対する幅方向平面度を測定し表１にまとめた。成型指標Ｆａ２．５を外れると該平面度が大きく悪くなることが判る。
【００５３】
（比較例２）（実施例２との比較）
実施例２で得たＣＢ含有成型用液を用いて、成型ドラムの角加速度を１０ｒａｄ／ｓとする以外は同一条件にて成型し、熱風乾燥して厚さ９９．５μｍの熱硬化ＰＩ無端管状フイルムを得た。得られた該フイルムの成型指標Ｆｂに対する幅方向平面度と電気抵抗値を測定し表１にまとめた。成型指標Ｆａ２．５を外れると該平面度は勿論、両者の電気抵抗値の差が２桁と悪くなり、ＣＢ分散に変化があったものと考えられる。
【００５４】
（比較例３）（実施例３に対する比較）
実施例３で得たホウ酸アルミ含有成型用液を用いて、成型ドラムの角速度を６ｒａｄ／ｓとする以外は同一条件にて成型し、熱風乾燥して厚さ１０１μｍの熱可塑ＰＩ無端管状フイルムを得た。得られた該フイルムの成型指標Ｆｂに対する幅方向平面度と耐屈曲性を測定し表１にまとめた。成型指標Ｆａ２．５を外れると該平面度は勿論、耐屈曲性も悪くなっており、ホウ酸アルミの分散に変化があったものと考えられる。
【００５５】
【発明の効果】
本発明は前記の通り構成されているので、次のような効果を奏する。
【００５６】
まず無端管状フイルムの特に幅方向の平面度ムラに関し、それが極めて小さいこと。これは例えばベルトとして使用する場合、回転蛇行とか接触圧ムラを起こすことがないので円滑にその作用を果たすことができる。
【００５７】
そしてある目的のために使用された無機添加剤含有の無端管状フイルムでは、その分散状態が極めて良好である。これは前記優れた平面度を有することは勿論、該フイルム自身の有する機械的物性を損なうことなく、該添加剤により付与さてる機能を十分に発揮することに繋がっている。
【００５８】
更に無端管状フイルムの内直径がより大きくなっても（例えば１ｍ）、幅方向の平面性への影響はなく、優れた厚み精度を維持することができる。これはより大きい径の該フイルムが迅速に容易に製造できることと、それに使用する成型ドラムの真円精度が少々悪くても良いということに繋がり、製造上も極めて有利になる。
【００５９】
例えば導電性ＣＢ粉体含有の無端管状フイルムは、前記優れた平面性は勿論、付与される体積抵抗値と表面抵抗値との差が極めて小さいことである。このことは、例えば除電又は帯電における印加電圧に依存性がないことと、経時変化がなく安定した電気抵抗特性を有しているものと言える。ここで樹脂として例えば熱硬化性ポリイミドを使用した場合の無端管状フイルムは、優れた耐熱性、耐薬品性及び機械的性質と共に、その優れた電気抵抗特性を有することで、例えばカラ−複写機の中間転写用ベルトは勿論、（加熱）定着兼用としても極めて有効な部材となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the provision of an endless tubular film having improved properties, particularly improved thickness accuracy (width direction) and dispersibility of inorganic additives, and use thereof. For example, an endless tubular polyamideimide or polyimide film using conductive carbon black as an inorganic additive is effective for use as an intermediate transfer belt in a color copying machine.
[0002]
[Prior art]
In general, it is well known to form a polymer solution into an endless tubular film by, for example, centrifugal casting. The method has advantages and disadvantages, and many improved techniques have been patented and published. However, in particular, the thickness accuracy in the width direction of the film tends to be poor, and it has not yet been solved to meet stricter accuracy requirements.
In addition, an endless tubular film obtained by adding an inorganic additive to a polymer solution and molding the same in order to add a certain function tends to be unevenly distributed without being uniformly dispersed throughout. Not only the mechanical properties of the film itself deteriorate, but also the function of the wrinkles that are uniformly applied tends to be non-uniform. In other words, at least in the endless tubular film produced by the centrifugal casting method, it is the actual situation that there is still no satisfactory quality and performance regarding the two points.
[0003]
[Problems to be solved by the invention]
The present invention has been intensively studied to solve the above two unsolved problems. As a result, the following means were found and the present invention was achieved.
[0004]
[Means for Solving the Problems]
That is, the present invention is described in claim 1 when the polymer liquid A containing no inorganic additive is used, and claim 2 when the polymer liquid B containing the inorganic additive based on claim 1 is used. Is.
In other words, the invention of claim 1 is characterized by an endless tubular film obtained by molding polymer liquid A without addition of an inorganic additive into an endless tube under the condition of the following formula 1 and heating and drying it in a rotating molding drum. To do.
(Formula 1)

(In Equation 1, Va is the viscosity of the polymer liquid A, r is the inner radius of the molding drum, and ω is the angular velocity of the molding drum)
The invention of claim 2 is characterized by an endless tubular film formed by rotating polymer liquid B with an inorganic additive into an endless tube under the condition of the following formula 2 in a rotating molding drum and drying by heating. It is.
(Formula 2)

(In Formula 2, Vb is the viscosity of the polymer liquid B, r is the inner radius of the molding drum, and ω is the angular velocity of the molding drum)
In addition, Claims 3 to 6 are dependent on Claims 1 and 2 and are preferred embodiments of the present invention, and Claim 7 is an endless tubular film obtained by being dependent on Claim 6 in a color copying machine. This invention is used as an intermediate transfer belt. The present invention will be described in detail in the following embodiments.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 will be described.
First, the polymer liquid A without addition of an inorganic additive to be molded here is mainly a thermoplastic or thermosetting resin (matrix) polymer, which does not contain at least an inorganic additive, and has a predetermined liquid viscosity. This is what makes liquid. The liquid may be a polymer solution obtained by dissolving the polymer in an organic solvent, or the polymer itself may be liquid in a normal state and no organic solvent may be used. Here, the latter case is generally observed when the polymer is a low molecular prepolymer that is liquid at room temperature, regardless of thermoplasticity or thermosetting. However, as seen in thermosetting, for example, thermosetting polyimide, when the prepolymer (precursor) is solid in a normal state, the organic solvent is used as a solution, which is a molding target.
[0006]
The thermoplastic resin in the polymer is not particularly suitable for the present invention as long as it is soluble in an organic solvent. For example, semi-synthetic cellulose, various polyesters, various polyamides (aliphatic, aromatic), various fluorine resins, various olefin polymers (straight chain, cyclic), various vinyl polymers, polyamideimide, thermoplastic polyimide, etc. It is done.
On the other hand, since thermosetting resins generally do not dissolve in organic solvents themselves, they are prepolymers, that is, low molecular levels that are uncured and liquid at room temperature, and are ester-based, epoxy-based, and phenolic. -Represented by rubber system, urethane system and silicone system. These are of low molecular level and are first molded into an endless tube and then polymerized by subsequent heat drying.
There is also a thermosetting polyimide, which is already a high molecular polymer, unlike the low molecular prepolymer as described above. However, this is insoluble in an organic solvent itself, and its precursor polyamic acid is dissolved, so that the one dissolved in an organic solvent is an object.
The prepolymer can be used for the above-mentioned thermoplastic resins, particularly various vinyl polymers that do not have an appropriate organic solvent.
[0007]
The polymer liquid A is used to form a high-quality and performance endless tubular film according to the present invention that is suitable for its properties, but it is based on extremely high functions (heat resistance, chemical resistance, mechanical properties). When obtaining as characteristics, for example, aromatic polyamide, polyamideimide, or polyimide is selected.
[0008]
When the polymer liquid A is determined, the polymer liquid A is first supplied into a rotating molding drum (the entire inner surface), and is molded into an endless tubular film under the condition of the above mathematical formula 1.
[0009]
Formula 1 is an empirical formula that has been found from various angles in order to solve the above-mentioned problem, particularly the thickness unevenness (flatness) (swelling degree) in the width direction of the endless tubular film obtained. Therefore, if such an empirical formula is followed, the causal relationship is not well understood how the thickness unevenness is solved.
[0010]
In Equation 1, Va is the viscosity of the polymer liquid A, and its unit is Pa · s (Pascal second). Here, the viscosity varies depending on the temperature, but it is a liquid viscosity at room temperature (20 to 25 ° C.) unless it is special (when it does not exhibit a liquid state unless heated to some extent). r is the inner radius of the molding drum, the unit is m, and ω ² Is the square of the angular velocity ω of the molding drum, and the unit is rad / s (radian per second). Hereinafter, the formula itself will be referred to as a molding index Fa for convenience.
The angular velocity is also obtained by dividing (2π) × (the number of revolutions of the forming drum rpm) by 60 seconds.
[0011]
Each condition factor is selected so that the molding index Fa is 2.5 or less, preferably 2.2 or less, and more preferably 1.9 or less. By making it below this numerical value, even if the molding drum rotates, it will not act as a centrifugal force substantially, and only under the absence of this centrifugal force, the problem of the present invention
(Effect) will be achieved. The lower limit of Fa should not be 0 because it is assumed that the molding drum is rotating at any low speed. This is because it is necessary to first mold into a desired endless tubular film while rotating at a very low angular velocity, and to heat and dry after molding efficiently and uniformly.
[0012]
Each factor constituting the Fa is basically determined by a few conditions when the polymer A liquid viscosity Va is determined. For reference, the numerical range of each factor is shown as an example. Keep it. First, the Va is about 0.2 to 10, preferably 0.5 to 7 Pa · s. The specific gravity of the polymer liquid A is greater than 1 and about 1.3 or less. r is about 0.1 to 0.5 m. ω is about 0.3 to 10, preferably 0.5 to 7, and more preferably 0.8 to 5 rad / s.
[0013]
The endless tubular film is manufactured in two steps: first, the polymer A solution is formed into an endless tube in a rotating forming drum (under the condition of the forming index Fa), and then heated and dried. However, the molding of the previous process is particularly important here. This is because, in this step, it is preferable to substantially form into a highly accurate endless tubular film having excellent flatness in the width direction according to the present invention.
Therefore, in order to effectively express the action and effect in the previous process, the molding using the following means is specifically preferable.
[0014]
The means is a method of discharging the polymer A liquid forcibly and uniformly on the inner surface of the drum while rotating the molding drum under the condition of Fa. Further, the method is the state of the discharged A liquid, that is, whether the liquid is discharged in a liquid state or is sprayed. In which state of discharge is preferably used depending on the viscosity Va of the liquid A, but the latter is more preferable for the following reasons.
In other words, in liquid ejection, the lower this is, depending on the liquid viscosity Va, there is a tendency that molding under the condition of Fa cannot be performed. This is because the liquid discharge itself becomes difficult to discharge uniformly as the value of Va becomes low, and as a result, it tends to rotate at a higher angular velocity for adjustment. Then, it can no longer be molded under the condition of Fa.
However, in spray discharge, it does not depend on the liquid viscosity Va, and can be discharged so that the entire inner surface is evenly applied even at a higher Va. Therefore, it rotates at such an angular velocity that a further uniform casting is performed. This is because the target endless tubular film can be efficiently molded even under an extremely low angular velocity (for example, about 0.3 rad / s).
[0015]
Examples of the mechanism centered on the nozzle can be exemplified as follows.
The nozzle is a slit nozzle having a predetermined width, and has a mechanism that can swing left and right and can be freely changed in distance from the inner surface of the molding drum. In addition, the mechanism moves horizontally to the left or right by a predetermined width in conjunction with the rotation speed. Further, in the liquid discharge, the supply source is a compressed air or a gear pump because it is only necessary to discharge from a nozzle of a predetermined size while controlling the discharge amount. However, in spray discharge, it is necessary to make it spray. For this purpose, a double-structure nozzle is used in which the nozzle for supplying the polymer A liquid is provided at the center, and the pressure air supply nozzle is provided with the nozzle sandwiched from both sides.
[0016]
If the film is molded into an endless tubular film under the condition of the molding index Fa, it is dried by heating until the endless tubular film that can maintain at least the shape is maintained while maintaining this condition. In the case of using a polymer dissolved in the organic solvent as a raw material, the heat drying is mainly performed by evaporating the solvent to dry, and in the case of using a low molecular weight prepolymer not containing the solvent as a raw material. The polymer is polymerized and converted into a polymer while being molded into the film. Accordingly, the heat drying conditions are at least a temperature higher than the boiling point of the solvent in the former case, a temperature higher than the polymerization temperature in the latter, and the time varies depending on the set temperature.
If the purpose of the initial heat drying is achieved and further heat drying is desired, the molding drum is continuously rotated (the speed may be the angular speed under the condition of the molding index Fa or higher. This may be carried out while being good) or may be separated from the drum and assembled in a separate step. In particular, in the case of the polymer A liquid using an organic solvent and when the polymer is the polyamic acid described above, heat drying incorporating the latter separate process is desirable. This is because the trace amount of the solvent remaining at a higher temperature is completely removed efficiently and that the polyamic acid is preferable for the final imidization. In the separate step, the peeled film may be simply put into a hot air dryer and heated, but once inserted into this using a cylindrical mold of the same diameter, this is put into a hot air dryer and heated. It is good (the dimensional accuracy is not confused).
[0017]
The rotating molding drum is a molding apparatus having the following mechanism. First of all, the inner surface is mirror-finished, and both sides of the inner circumferential end are provided with a barrier for preventing liquid leakage (not necessarily required). Both sides of the metal inner tube are used as a molding drum and placed on a rotating roller. Has been. A far-infrared heater is provided on the outer upper surface of the drum, and the heater or the like is provided in the roller to heat the inside of the drum. One of the supply nozzles for supplying the polymer liquid A and a supply / discharge nozzle for positively removing the evaporated organic solvent out of the system are provided with a removable mechanism inside the drum. ing. The drum rotates indirectly by the rotation of the roller.
[0018]
Next, claim 2 will be described.
Here, the polymer B liquid in which the inorganic additive is contained in the polymer A liquid in claim 1 is similarly molded, heat-dried under the conditions of Formula 2, and an endless tubular film containing the inorganic additive is obtained. is there.
[0019]
First of all, inorganic substances (single or compound) are particularly targeted as additives in endless tubular films formed by centrifugal molding as described above, and the dispersion of the inorganic substances is unevenly distributed and is not uniform. Evil is likely to occur. This is presumably because, in general, the inorganic substance itself has no affinity for the polymer and the organic solvent, and a large specific gravity is further promoted by a mechanical action called centrifugal force. This is because the present invention is mainly aimed at solving this problem. Therefore, even if the means of the present invention is applied to additives other than the additive, for example, organic additives, there is no effect or it is small, and it does not mean that it cannot be applied.
[0020]
In Formula 2, the formula itself is referred to as a molding index Fb for convenience. This Fb eliminates unevenness in the width direction (swell) in the endless tubular film molded under the conditions of Formula 1, and also causes uneven dispersion by containing the inorganic additive. As a result of various studies to solve the problem, the numerical value obtained by the empirical formula finally found is 2.5 or less which is the same as that of the first aspect. Since Fb contains an inorganic additive, the numerical setting in specific implementation may change accordingly, but it can be performed in the same manner within the same frame as Fa.
The Fb (the specific gravity of the inorganic additive) is the true specific gravity, not the apparent specific gravity. The molding index Fa has a shape proportional to (specific gravity of the polymer liquid A), but Fb has a shape proportional to the specific gravity of the inorganic additive. This is because when an inorganic additive is used, it is much larger than the specific gravity of the polymer liquid A, so that the influence is large and the specific gravity of the polymer liquid A is not substantially affected.
[0021]
As for the specific gravity of the inorganic additive, the larger the difference from the specific gravity of the polymer A liquid itself, the greater the effect described in the present invention, but if it is too large, there is a risk of sedimentation and separation until the molding operation. Is big. From this point of view, it is numerically about 1.3 to 5, preferably 1.5 to 4.
[0022]
The additive is generally mixed with plastic for various purposes and is not particularly limited. For example, as a typical example, flame retardant is Ca (OH). ₂ The mechanical strength improvement is 9Al ₂ O ₃ ・ 2B ₂ O ₃ , Thermal conductivity is BN, piezoelectricity is BaTiO ₃ Light scattering / reflectivity is TiO ₂ 、 Slidability is MoS ₂ Examples of the semiconductive property include conductive carbon black. Of course, this additive is in the form of a fine powder of about several μm or less, and what specific size should be determined may be determined by preliminary experiments. Further, the amount added may be determined by preliminary experiments so that the function is imparted while maintaining the original physical properties of the polymer.
[0023]
In general, a polymer B solution is prepared by dissolving a predetermined amount of a polymer in a predetermined amount of an organic solvent in advance, gradually adding a predetermined amount of an inorganic additive while stirring, and finally adding a bolus. -Thoroughly mix and disperse with Lumil or the like. In this mixing, for example, a surfactant may be added to improve dispersibility.
[0024]
Next, polyamideimide (hereinafter referred to as PAI) and polyimide (hereinafter referred to as PI) having higher heat resistance, mechanical properties and the like are used as polymers, and conductive carbon black (hereinafter simply referred to as CB) is added and mixed as an inorganic additive. The production of an endless tubular film imparted with semiconductivity will be described in more detail using the obtained polymer B solution by spin molding under the condition of the molding index Fb and heat drying.
[0025]
First, as is generally known, the PAI has an equimolar amount of an organic tricarboxylic acid monoanhydride and an organic diamine having an aprotic polar property such as dimethylacetamide, dimethylformamide, dimethylsulfoxide, or N-methylpyrrolidone. Obtained by polycondensation reaction in an organic solvent. If the reaction temperature at this time is normal temperature or lower, the PAI polyamic acid solution can be obtained, and if the reaction temperature is higher than normal temperature, imidization can proceed to obtain a PAI solution all at once. Generally, in the case of PAI, since it dissolves in the solvent itself, it is preferable to obtain it with a PAI solution. Specifically, as an organic tricarboxylic acid monoanhydride, for example, trimellitic acid monoanhydride, as an organic diamine, for example, 3,3′-diaminobenzophenone, P-phenylenediamine, 4,4′-diaminodiphenyl, 4,4 '-Diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, bis [4- {3- (4-aminophenoxy) benzoyl} phenyl] ether, 4,4'-bis (3-aminophenoxy) biphenyl, bis [ 4- (3-aminophenoxy) phenyl] sulfone, 2,2′-bis [4- (3-aminophenoxy) phenyl] propane, and the like. Of course, the diamine is not limited to one kind, and may be copolymerized using two or three kinds.
In the organic diamine, those having —O—, —SO 2 —, —CO— or an alkylene group tend to have higher solubility of the obtained PAI itself.
[0026]
On the other hand, PI can be obtained by polycondensation reaction of an equimolar amount of an organic tetracarboxylic dianhydride and an organic diamine in the aprotic polar organic solvent. A polyamic acid solution of PI can be obtained as a PI solution by progressing imidization under heating at room temperature or higher. However, in the case of thermosetting PI, it does not dissolve in the solvent as the imidization proceeds, so it is necessary to react at a low temperature of room temperature or lower and stop at the polyamic acid stage.
Specific examples of the organic tetracarboxylic dianhydride include pyromellitic dianhydride, 2, 2 ′, 3, 3′-biphenyltetracarboxylic dianhydride, 3, 3 ′, 4, 4′-benzophenone. Tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride and the like. Examples of the organic diamine include aromatic diamines exemplified in the PAI. Of course, the above starting materials are not limited to one each, but may be obtained by mixing two or three kinds and carrying out a copolycondensation reaction.
In the case of this PI, two to three —O—, —SO 2 —, —CO—, alkylene groups (C ₂ Etc.), the PI itself is dissolved in the solvent and has thermoplasticity. Therefore, when the polycondensation reaction is performed with such a combination of raw materials, it is preferable to react at a temperature higher than room temperature and obtain the PI solution all at once.
In addition, each polymer liquid obtained by the above is also an illustration of the polymer A liquid of Claim 1.
[0027]
In addition, whether the PAI or the PI is used, a polymer A or B obtained by appropriately blending them may be used. Further, the polymer A or B may be obtained by appropriately mixing the acid component of PAI and the acid component of PI, and using this as an acid component to polycondensate the organic diamine in the same manner.
[0028]
And CB is essentially conductive in itself (for example 10 ¹ There are no other conditional restrictions as long as the powder has Ω · cm or less. That is, it is said that it is not influenced by generally known characteristics (values) such as its manufacturing method, structure, volatile matter, DBP oil absorption, specific surface area. This is also one of the features not found in the prior art (many patent applications characterized by CB with various characteristic values as a condition).
[0029]
The CB powder is semiconductive (10) ² -10 ¹³ Ω · cm or 10 ² -10 ¹³ In the range of about Ω / □, a corresponding amount is added to the polymer liquid A to obtain a polymer liquid B with sufficient mixing dispersion. The corresponding mixing amount is about 5 to 25% by weight with respect to the polymer (solid content), and after preliminary mixing, it is thoroughly mixed and dispersed by a ball mill or the like.
The obtained polymer liquid B is not limited to CB powder, but other inorganic additives may be gradually separated when stored for a long time. It is better to use the mold as soon as possible.
[0030]
The obtained PAI solution, (thermoplastic) PI solution, or (thermosetting PI) polyamic acid solution is obtained by any of the methods described in claim 1 (under Fb = 2.5 or less). It is fed into a molding drum that rotates at a low angular velocity and molded into an endless tubular film, but full-scale heat drying from the outside starts after being applied to the entire inner surface. The heating temperature here is preferably about 10 ° C. higher than the boiling point of the organic polar solvent used and 200 ° C. or lower in the case of the polyamic acid solution. This is because at 200 ° C. or higher, the imidization reaction also proceeds in the molding drum, and bubbles and the like are likely to be contained therein, which is not preferable. Even when the PAI solution or PI solution is used, it is stopped in a state where it is left to some extent (for example, about 5 to 30%) rather than being heated and dried until all of the solvent is evaporated and removed in the molding drum, and once peeled off and taken out. It is preferable to take a method of drying by heating again in the above-described separate process. This is also for removing the remaining trace amount of the solvent more quickly and eliminating the risk of bubbles.
In the polyamic acid, it is preferable that the heating temperature in this separate step is gradually raised from about room temperature to about 450 ° C., and finally brought to about 450 ° C. Of course, even in the case of PAI solution and PI solution, all of them may not be imidized. In such a case, it is necessary to complete the imidation by heating to a temperature of 200 ° C. or higher.
[0031]
Incidentally, the polymer B liquid viscosity Vb, the inner radius of the molding drum, the angular velocity ω, and the molding means in the molding index Fb are performed within the range often described in claim 1 (although there is a slight difference in condition setting). So there is no difference.
[0032]
The endless tubular film manufactured by the means described above has the following characteristics.
In addition, although the thickness of this film changes with usages etc., generally it is about 0.03-0.3 mm. Of course, the present invention is not applicable to thicker ones.
First, whatever width is taken, thickness unevenness due to undulation or the like is extremely small (excellent in the width direction flatness), for example, numerically within 2 mm, and further within 1.5 mm. Of course, there is no problem in the longitudinal direction (rotating direction) within 1 mm. An endless tubular film molded under the condition that the molding index Fa (Fb) exceeds 2.5 (that is, under centrifugal force) has a large unevenness (swell) particularly in the width direction. When used as a belt, it may cause meandering, and if the roller is rotated while in contact with the surface of the belt, the contact pressure may be greatly uneven and cannot be used. It becomes a fatal defect. Therefore, it can be said that the plane accuracy in the width direction is an inevitable condition for the belt.
[0033]
In addition, in an endless tubular film containing an inorganic additive, the dispersion is not unevenly distributed and is extremely uniform. Even if many of these additives are contained, the mechanical properties of the film itself are maintained as they are and new functions are added. For example, the CB-containing endless tubular film maintains the flatness and has very excellent electrical resistance characteristics. For example, the difference between the volume resistance value and the surface resistance value is extremely small, being one digit or less and 0.5 digits or less. There is a large difference between the two obtained under the centrifugal force, but it can be said that this clearly comes from the difference in the dispersion state. If there is no difference in the resistance value, it means that there is no dependency on the applied voltage in, for example, static elimination or charging, and that there is no change with time.
The endless tubular film obtained under the centrifugal force tends to vary in the electric resistance value depending on its position, but this is not the case in the present invention.
[0034]
Furthermore, even if the inner diameter of the endless tubular film becomes larger (for example, 1 m), not only the flatness in the width direction but also the overall thickness accuracy does not change and the high accuracy is maintained. In general, in molding under centrifugal force, as the inner diameter becomes larger, the thickness accuracy becomes worse, and the diameter has a limit. This is because, together with the diameter increase of the molding drum, there is a runout due to rotation and it is difficult to manufacture the drum with high accuracy. In the present invention, there is no core blur due to rotation in any size of the forming drum, and even if the manufacturing accuracy of the drum is slightly worse, the influence on the film due to this is small and does not cause a problem.
[0035]
The endless tubular film according to the present invention is used for various applications because of its excellent characteristics as described above. Among them, PAI, thermoplastic PI, or thermosetting PI is used as a polymer, and CB powder is mixed with this to electrically The film imparted with resistance is an intermediate transfer belt of a color copying machine.
It is effective as Among these belts, a belt with thermosetting PI is more effective. This is because it can be used as an intermediate belt for heat fixing and transferring.
[0036]
【Example】
Hereinafter, the present invention will be described in more detail with reference to comparative examples.
In this example, the flatness in the width direction, the volume resistance value (Rv), and the surface resistance value (Rs) are values measured as follows.
◎ Flatness in the width direction ・ ・ Laser displacement meter manufactured by Keyence Corporation with an endless tubular film cut to a predetermined width stretched on two rollers with a diameter of 30 mm with a tension of 35 N (Type LK080) is irradiated with laser light in the width direction, and the distance between the film surface and the laser light is automatically recorded. A peak (Max value) and a valley (Min value) (swell) are read from the recorded data, and the difference between the two is used as a measured value.
◎ Rv and Rs ・ ・ A value measured directly in 30 seconds under the application of 100V voltage using a resistance measuring instrument “HIRESTA HR Blob” manufactured by Mitsubishi Chemical Corporation.
[0037]
(Example 1) (Claim 1)
First, an equimolar amount of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether is subjected to a polycondensation reaction at 20 ° C. in an N-methylpyrrolidone solvent, and an aromatic polyamide having a solid concentration of 18% by weight. 10 kg of an acid solution (hereinafter referred to as PA solution 1) was obtained. This product had a viscosity of 4.2 Pa · s and a specific gravity of 1.12.
[0038]
A part of the PA solution 1 was used to mold an endless tubular film of thermosetting PI under the following conditions.
The molding apparatus used here has the mechanism described in the text (paragraph 0018).
A molding drum with an inner diameter of 270 × inner diameter and a width of 500 mm is placed on two rotating rollers with heat sources (hot water) inside, and the rotation is started slowly at an angular velocity of 6 rad / s at room temperature. I did. And, from the slit nozzle with a width of 50 mm that moves the PA liquid 1 left and right, 2.5 kg / cm ² Injection was started toward the inner surface of the drum at a pressure of. The nozzle moved from the right to the left in synchronization with the rotation, and the injection was stopped when the predetermined coating thickness was reached. Then, while maintaining the same angular velocity, heating with a far-infrared heater is started, heating is performed at a heating rate of about 17 ° C./min, and when the temperature reaches 150 ° C., the heating operation is stopped and further 60 Heated for minutes. During this heating, the solvent to be evaporated was positively discharged out of the system using an intake / exhaust nozzle. Finally, when the heating was stopped and cooled to room temperature, the rotation was stopped and the molded body was peeled off from the drum.
The molded body is an endless tubular polyamic acid film.
[0039]
Then, the obtained molded body was formed into a hollow cylindrical metal mold having an outer diameter of 265 mm and a width of 550 mm (surface is R _Z The whole was put into a hot air dryer and heated. As heating conditions, first, 120 minutes were required, and the temperature was gradually raised between 320 ° C., followed by heating at the temperature for 60 minutes. Finally, it was taken out from the dryer and cooled to room temperature, and then removed from the mold. The thickness of the thermosetting PI endless tubular film thus produced was 69.5 μm, and the flatness in the width direction with respect to the molding index Fa was summarized in Table 1.
[0040]
(Table 1)

[0041]
(Example 2) (corresponding to claim 2)
2 kg of PA solution 1 obtained in Example 1 was collected, and N-methylpyrrolidone was added to the solution while stirring to dilute and dissolve so that the solid content was 17% by weight. Then, 2 kg of this solution is taken into a dissolver and stirred while stirring. ^-1 Ω · cm CB powder (true specific gravity 1.75)
After gradually adding 50 g (12.8% by weight with respect to the solid content) and premixing, this was transferred to a ball mill and mill-mixed to sufficiently disperse to obtain a molding liquid. The viscosity of this product was 4.3 Pa · s.
[0042]
Then, using the above molding liquid, under the same conditions as in Example 1, it was first molded into an endless tubular film of polyamic acid, taken out from the molding drum, inserted into a hollow cylindrical metal mold, dried with hot air, and remained. The film was imidized with the complete removal of the solvent to obtain a thermosetting polyimide endless tubular film having a thickness of 70 μm. However, the angular velocity is 5 rad / s and the injection pressure is 2.0 kg / cm. ² Met.
[0043]
Then, the flatness in the width direction and the electric resistance value with respect to the molding index Fb of the obtained thermosetting polyimide endless tubular film were measured and summarized in Table 1.
[0044]
(Example 3) (corresponding to claim 2-when thermoplastic PI is used as a matrix resin)
An equimolar amount of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and bis [4- {3- (4-aminophenoxy) benzoyl} phenyl] ether in a dimethylacetamide solvent, 35 A polycondensation reaction was performed at ° C to obtain 5 kg of a solution having a solid concentration of 14% by weight. When a part of the sample was collected and subjected to IR analysis, only absorption derived from an imide bond was observed, and absorption derived from an amide bond was not confirmed (hereinafter referred to as thermoplastic PI liquid 3). The viscosity of the liquid was 2.5 Pa · s and the specific gravity was 1.06.
[0045]
Then, 1 kg of the thermoplastic PI liquid 3 was sampled and placed in a dissolver while stirring. ₂ O ₃ ・ 2B ₂ O ₃ (Aluminum borate) (true specific gravity 3.0) (length 0.5-1.0 μm-diameter 5-10 μm whisker) 8 g (about 5.4 wt% based on solid content) was gradually added. After pre-mixing, this was transferred to a ball mill, mill-mixed and sufficiently dispersed to obtain a molding liquid. The viscosity of this product was 2.8 Pa · s.
[0046]
Then, the molding liquid was first molded in the molding drum under the following conditions using the molding apparatus of Example 1 under the same procedure.
In other words, while the molding drum rotates at an angular velocity of 3 rad / s, the injection pressure is 1.5 kg / cm. ² After spraying, heating was started while maintaining the same speed, and after 80 minutes, the temperature was raised to 170 ° C., and in this state, heating was continued for 60 minutes. Then, after cooling to room temperature, the rotation is stopped and peeled off, then inserted into a hollow cylindrical metal mold and placed in a hot air dryer, heated at 260 ° C for 60 minutes, cooled to room temperature and then removed. A corresponding reinforced 100 μm thick thermoplastic PI endless tubular film was obtained.
[0047]
The obtained endless tubular film was measured for flatness in the width direction and bending resistance, and are summarized in Table 1.
The bending resistance was defined as the number of times the film was bent at an angle of 135 degrees and when it was cracked.
[0048]
(Example 4) (corresponding to claim 2-when PAI is a matrix resin)
An equimolar amount of trimellitic acid monoanhydride and 4,4'-diaminodiphenylmethane is subjected to a polycondensation reaction at 30 ° C in an N-methylpyrrolidone solvent to obtain 5 kg of an aromatic PAI solution having a solid content of 29% by weight. Obtained.
In addition, when IR analysis was conducted by taking a part of the solution, no absorption based on unclosed amic acid was observed, but an amide group based on polycondensation of one carboxyl group and an amino group and one of the amic acid The absorption was based on an imide group that was ring-closed and condensed with polycondensation.
[0049]
Then, 2 kg of the PAI solution was sampled and placed in a dissolver. ^-1 96 g (14.2 wt% based on solid content) of Ω · cm CB powder (true specific gravity 1.82) was gradually added and premixed, then transferred to a ball mill and mixed with the mill. Then, it was sufficiently dispersed to obtain a molding liquid. The viscosity of this product was 5.4 Pa · s.
[0050]
Then, the molding liquid was first molded in the molding drum under the following conditions using the molding apparatus of Example 1 under the same procedure.
In other words, a molding drum having an inner diameter of 700 mm and a width of 750 mm was used, and the injection pressure was 2.0 kg / cm while rotating the drum at an angular velocity of 4 rad / s. ² After spraying, heating was started while maintaining the same speed, and after 90 minutes, the temperature was raised to 160 ° C., and in this state, heating was continued for 60 minutes. Then, after cooling to room temperature, the rotation is stopped and peeled off, and then inserted into a hollow cylindrical metal mold, put into a hot air dryer, heated at 210 ° C for 50 minutes, cooled to room temperature and then removed. A corresponding PAI endless tubular film having a thickness of 90 μm was obtained.
[0051]
Then, the flatness and electric resistance value in the width direction with respect to the molding index Fb of the obtained PAI endless tubular film were measured and summarized in Table 1.
[0052]
(Comparative Example 1) (Comparison with Example 1)
The PA liquid 1 obtained in Example 1 was molded under the same conditions except that the angular acceleration of the molding drum was 10 rad / s, and dried with hot air to obtain a thermosetting PI endless tubular film having a thickness of 71 μm. . The flatness in the width direction with respect to the molding index Fa of the obtained film was measured and summarized in Table 1. It can be seen that when the molding index Fa2.5 is deviated, the flatness is greatly deteriorated.
[0053]
(Comparative Example 2) (Comparison with Example 2)
Using the CB-containing molding liquid obtained in Example 2, molding was performed under the same conditions except that the angular acceleration of the molding drum was 10 rad / s, followed by drying with hot air, and a thermosetting PI endless tubular tube having a thickness of 99.5 μm. I got a film. The flatness and the electric resistance value in the width direction with respect to the molding index Fb of the obtained film were measured and summarized in Table 1. If the molding index Fa2.5 is deviated, the flatness as well as the difference between the two electrical resistance values deteriorates by two digits, and it is considered that the CB dispersion has changed.
[0054]
(Comparative Example 3) (Comparison with Example 3)
A thermoplastic PI endless tubular film having a thickness of 101 μm was molded using the aluminum borate-containing molding liquid obtained in Example 3 under the same conditions except that the angular velocity of the molding drum was set to 6 rad / s and dried with hot air. Got. The obtained film was measured for flatness in the width direction and bending resistance with respect to the molding index Fb and summarized in Table 1. When the molding index Fa2.5 is deviated, the flatness as well as the bending resistance are deteriorated, and it is considered that the dispersion of aluminum borate has changed.
[0055]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects.
[0056]
First of all, the flatness unevenness in the width direction of the endless tubular film is extremely small. For example, when this is used as a belt, it does not cause rotating meandering or uneven contact pressure, so that it can perform its function smoothly.
[0057]
And in the endless tubular film containing an inorganic additive used for a certain purpose, the dispersion state is very good. This not only has the above-mentioned excellent flatness, but also leads to fully exerting the function imparted by the additive without impairing the mechanical properties of the film itself.
[0058]
Furthermore, even if the inner diameter of the endless tubular film becomes larger (for example, 1 m), the flatness in the width direction is not affected, and excellent thickness accuracy can be maintained. This leads to the fact that the film having a larger diameter can be produced quickly and easily, and the roundness accuracy of the molding drum used therefor may be slightly worse, which is extremely advantageous in production.
[0059]
For example, an endless tubular film containing a conductive CB powder has an extremely small difference between a volume resistance value and a surface resistance value, as well as the excellent flatness. This can be said, for example, that there is no dependency on the applied voltage in static elimination or charging, and that there is no change with time and stable electrical resistance characteristics. Here, an endless tubular film in the case of using, for example, a thermosetting polyimide as a resin has excellent electric resistance characteristics as well as excellent heat resistance, chemical resistance and mechanical properties. The intermediate transfer belt is of course an extremely effective member for both (heating) and fixing.

Claims (6)

In molding drum to rotate, the polymer - liquid A is either polyamide imide or polyamic acid, was molded into an endless tubular under the conditions of the following Equation 1, formed by heating and drying, the width direction flatness within 2mm An endless tubular film characterized by being .
(Formula 1)

(Where Va is the viscosity (Pa · s) of polymer liquid A, r is the inner radius (m) of the molding drum, and ω is the angular velocity (rad / s) of the molding drum) In a rotating molding drum, a polymer liquid B containing polyamideimide or polyamic acid and an inorganic additive is molded into an endless tube under the condition of the following formula 2 and dried by heating. The flatness in the width direction is within 2 mm. An endless tubular film characterized by being
(Formula 2)

(However Viscosity (Pa · s of Vb in equation polymer solution B), r is the inner radius of the molding drum (m), omega is shows the angular velocity (rad / s) of the molding drum) The endless tubular film according to claim 2, wherein the inorganic additive is a conductive carbon black. Endless tubular fill-arm according to billed to claim 2 or 3 which is for the intermediate transfer belt of a color copying machine. In a rotating molding drum, the polymer liquid A, which is either polyamideimide or polyamic acid, is molded into an endless tube under the condition of the following formula 1, and is heated and dried. Within endless tubular film manufacturing method.
(Formula 1)

(Where Va is the viscosity (Pa · s) of polymer liquid A, r is the inner radius (m) of the molding drum, and ω is the angular velocity (rad / s) of the molding drum) In a rotating molding drum, a polymer liquid B containing polyamideimide or polyamic acid and an inorganic additive is molded into an endless tube under the condition of the following formula 2 and dried by heating. Is a manufacturing method of endless tubular film within 2 mm.
(Formula 2)

(Where Vb is the viscosity (Pa · s) of polymer liquid B, r is the inner radius (m) of the molding drum, and ω is the angular velocity (rad / s) of the molding drum)