JP4742396B2 - Biaxially oriented polyester film and method for producing the same - Google Patents

Description

ただし、上記式中Ｒ₁ は、６〜３０個の炭素原子を有する２価の芳香族または脂肪族残基；Ｒ₂ は６〜３０個の炭素原子を有する２価の芳香族残基、２〜２０個の炭素原子を有するアルキレン基、２〜２０個の炭素原子を有するシクロアルキレン基、及び２〜８個の炭素原子を有するアルキレン基で連鎖停止されたポリジオルガノシロキサン基からなる群より選択された２価の有機基である。
【００２２】
上記Ｒ₁ 、Ｒ₂ としては、例えば、下記式群に示される芳香族残基
【化２】

を挙げることができる。
【００２３】
本発明では、ポリエステル（Ａ）との相溶性、コスト、溶融成形性等の観点から、下記式で示される構造単位を有する、２，２−ビス［４−（２，３−ジカルボキシフェノキシ）フェニル］プロパン二無水物とｍ−フェニレンジアミン、またはｐ−フェニレンジアミンとの縮合物が好ましい。
【化３】

このポリエーテルイミドは、“ウルテム”（登録商標）の商標名で、ジーイープラスチックス社より入手可能である。
【００２４】
ここでいう相溶とは、得られたチップのガラス転移温度（Ｔｇ）が単一であることにより判断できる。。このように両者が相溶した場合のＴｇは、ポリエチレンテレフタレート（Ａ）のＴｇとポリエーテルイミドのペレット（Ｂ）のＴｇの間に存在することが一般的に知られている。なお、単一のガラス転位点温度（Ｔｇ）を有するとは、理想的には、文字通り、Ｔｇが唯一つのみ認められ、それ以外のＴｇないしはそれに相当するものが全く認められないことであるが、Ｔｇの熱流束のギャップ以外に熱流束のギャップ様のものが認められたとしても、前記Ｔｇの１／１０以下の熱流束のギャップである場合には、これを無視し、単一のガラス転位点温度（Ｔｇ）を有するものと見なす。また、ガラス転移温度付近に、５ｍＪ／ｍｇ以下のショルダーがあっても、単一のＴｇを有するものと見なす。なお、本発明で単一のガラス転移点温度を有する二軸配向ポリエステルフィルムというのは、フィルムの少なくとも１層がかかる特質を有することを指している。従って、本発明のフィルムに、発明の効果を妨げない範囲で、ガラス転移点の異なるフィルムが積層されていても良い。但し、積層される各層間のガラス転移点があまり異なるとフィルム製造が困難となるので、ガラス転移点の差は５０℃以下が好ましく、３０℃以下がより好ましい。但し、コーティング層はこの限りでないことは言うまでない。
【００２５】
本発明において、ポリエーテルイミド（Ｂ）をポリエステル（Ａ）に添加する時期は、特に限定されないが、ポリエステルの重合前、例えば、エステル化反応前に添加してもよいし、重合後に溶融押出前に添加してもよい。また、溶融押出前に、ポリエステル（Ａ）とポリエーテルイミド（Ｂ）をペレタイズしてもよい。
【００２６】
本発明の二軸配向ポリエステルフィルムでは、広角Ｘ線回折のディフラクトメータ法による結晶配向解析で該二軸配向ポリエステルフィルムをその法線を軸として回転した時に得られる該二軸配向ポリエステル主鎖方向の結晶面の回折ピークの円周方向の半価幅が５５〜８５度の範囲であることが必須である。ポリエステル主鎖方向の結晶面の回折ピークの円周方向の半値幅は二軸配向ポリエステルフィルムの結晶の配向の方向の分布の広がりを表すものであり、この半価幅が５５度未満の場合、フィルムの寸法安定性に劣って保存安定性が悪化したり、フィルムの引裂伝播抵抗が小さくなってテープ破断が生じ易くなったりする。また、半値幅が８５度を越える場合には、フィルムの面内の全方位に高強度であるフィルムが得られず、本発明の目的を達成できない。ここで、ポリエステル主鎖方向の結晶面とは、広角Ｘ線ディフラクトメータ法によって回折ピークとして検知される結晶面の中で、その法線がポリエステル主鎖方向に最も近い結晶面であり、例えば、ポリエチレンテレフタレートでは（−１０５）面、ポリエチレン−２,６−ナフタレートでは（−３０６）面である。前記半価幅は、６０〜８５度の範囲がより好ましく、６５〜８０度の範囲が、本発明の効果を得る上で最も好ましい。
【００２７】
本発明の二軸配向フィルムについて、広角Ｘ線回折法から得られるポリエステル主鎖方向の結晶サイズは、特に限定されないが、４０オングストローム以上から９０オングストローム以下の範囲であることが好ましい。ここで、ポリエステル主鎖方向とは、ポリエステル主鎖方向に最も近い、結晶面の法線方向であり、例えば、ポリエチレンテレフタレートでは（−１０５）面、ポリエチレン−２，６−ナフタレートでは（−３０６）面の法線方向である。該結晶サイズが４０オングストローム未満では、テープの伸び変形が大きくなって、エッジダメージも発生し易く、またテープ加工後の保存安定性が悪化する。また、結晶サイズが９０オングストロームを越えるとテープ破断の発生頻度が高くなることがある。該結晶サイズは、使用するポリエステルによって変わるが、ポリエチレンテレフタレートの場合、４５オングストローム以上から８５オングストローム以下の範囲がより好ましく、５０オングストローム以上から８０オングストローム以下の範囲がさらに好ましい。また使用するポリエステルがポリエチレン−２，６−ナフタレートの場合には、５０オングストローム以上から６５オングストローム以下の範囲がさらに好ましい。
【００２８】
本発明の二軸配向ポリエステルフィルムのポリエーテルイミド（Ｂ）の含有量は、特に限定されないが、１〜５０重量％の範囲にあることが好ましい。さらに好ましくは、５〜３０重量％の範囲であり、より好ましくは、１０〜２５重量％の範囲である。ポリエステル（Ａ）とポリエーテルイミド（Ｂ）の溶融粘度は大きく異なるため、ポリエーテルイミド（Ｂ）の含有量が１重量％未満であれば、押出機にて十分な混練を得て互いに相溶することが困難なことがある。また、ポリエーテルイミド（Ｂ）の含有量が５０重量％を超える量であれば、押出成形加工が困難であったりして、さらに得られたポリエステルフィルムに十分な強度を発現するために、延伸加工を施すことが困難であったりすることがある。
【００２９】
本発明の二軸配向ポリエステルフィルムの長手方向のヤング率と幅方向のヤング率の和は、特に限定されないが、１０〜２５ＧＰａの範囲であることが好ましく、より好ましくは１２〜２２ＧＰａ、さらに好ましくは１４〜２０ＧＰａである。該ヤング率の和が１０ＧＰａ未満であれば、例えば、磁気記録媒体用などに用いる場合、走行時の磁気記録ヘッドやガイドピンから受ける張力のため、磁気テープに伸び変形が生じやすくなり、さらに電磁変換特性（出力特性）に悪影響を与えたりして、実用上使用に耐えないことがある。また、該ヤング率の和が２５ＧＰａを越えるフィルムは工業的に製造が困難であったり、フィルムの耐引裂性や寸法安定性が著しく低下したりすることがある。
【００３０】
本発明の二軸配向ポリエステルフィルムの長手方向と幅方向の温度１００℃、３０分における熱収縮率は、特に限定されないが、テープの伸び変形性および保存性の観点から、いずれも０．０１〜２．０％であることが好ましい。より好ましくは、０．０１〜１．５％であり、さらに好ましくは、０．０１〜１．０％である。温度１００℃の熱収縮率が２．０％を越える場合は、寸法安定性が損なわれやすくなることがあり、例えば磁気記録媒体用においては、ベースフィルムの磁気層を塗布するなどのフィルム加工工程における熱履歴や走行時の磁気テープと磁気記録ヘッドとの摩擦熱による磁気テープの昇温時にテープの熱変形が起こりやすくなったり、テープの保存性が悪化することがある。また、温度１００℃の熱収縮率が０．０１％未満の場合には、フィルムが膨張して、しわが発生したりすることがある。
【００３１】
本発明の二軸配向ポリエステルフィルムは、特に限定されないが、エチレンテレフタレート単位を主たる成分とするポリエステル（Ａ）とポリエーテルイミド（Ｂ）からなる成分を含有する場合、その補外ガラス転移開始温度（Ｔｇ−onset ）が９０〜１５０℃であることが好ましい。Ｔｇ−onsetは、より好ましくは９５〜１３０℃、さらに好ましくは１００〜１２０℃の範囲内にあることである。Ｔｇ-onsetが９０℃未満であれば、フィルムの寸法安定性向上について、本発明の効果が小さかったりすることがある。また、Ｔｇ-onsetが１５０℃を越える温度であれば、溶融成形性や延伸加工性などの成形加工の点で劣ったりすることがある。
【００３２】
本発明の二軸配向ポリエステルフィルムは、単層でも２層以上の積層構造でもよい。特に限定されないが、２層以上の積層構造である方がより好ましい。単層であると、例えば、磁気記録媒体用として用いる場合、粒子を含有させると、表面の突起がそろわず、電磁変換特性や走行性が悪化する場合がある。さらに、３層の場合に本発明の効果がより一層良好となり好ましい。最外層の厚みは、特に限定されないが、最外層に含有された粒子の平均径の０．１〜１０倍であることが、本発明の効果がより一層良好となり好ましい。なぜならば、この範囲の下限値を下回ると、電磁変換特性の不良となる恐れがあり、一方、この範囲の上限値を超えると走行性の不良の恐れがあるからである。また、積層させる場合、２層以上の積層構造の中で、少なくとも１層がポリエステル（Ａ）とポリエーテルイミド（Ｂ）からなる。他の層は特に限定されないが、ポリエステルが好ましく例示され、そのポリエステルとしては、特に限定されないが、エチレンテレフタレート、エチレン−α,β−ビス（２ークロルフェノキシ）エタン−４,４’−ジカルボキシレート、エチレン２,６−ナフタレート単位から選ばれた少なくとも一種の構造単位を主要構成成分とする場合に、特に好ましい。
【００３３】
ポリエステル（Ａ）とポリエーテルイミド（Ｂ）からなる層を内層に配した場合、保存性や引張強度向上などの効果が得られる。その場合その厚さは全体の厚さの８０％以上であることが好ましい。また、外層に配した場合には、走行耐久性向上に効果がある。その場合その厚さは０．１μｍ以上であることが好ましい。
【００３４】
本発明のポリエステル（Ａ）の固有粘度は、特に限定されないが、フィルム成形加工の安定性やポリエーテルイミド（Ｂ）との混合性の観点から、０．５５〜３．０（ｄｌ／ｇ）の範囲であることが好ましく、さらに好ましくは、０．６０〜２．０（ｄｌ／ｇ）である。また、二軸配向ポリエステルフィルムの固有粘度は、特に限定されないが、フィルム成形加工の安定性や寸法安定性などの観点から、０．５０〜２．０（ｄｌ／ｇ）の範囲であることが好ましく、さらに好ましくは０．５５〜１．０（ｄｌ／ｇ）である。
【００３５】
本発明の二軸配向ポリエステルフィルムは、本発明を阻害しない範囲内で、熱安定剤、酸化防止剤、紫外線吸収剤、帯電防止剤、難燃剤、顔料、染料、脂肪酸エステル、ワックスなどの有機滑剤などが添加されてもよい。また、フィルム表面に易滑性や耐磨耗性、耐スクラッチ性等を付与するために、積層フィルムの最外層に無機粒子、有機粒子などを添加すると、例えば、磁気記録媒体用などにおいて有用である。該添加物としては、クレー、マイカ、酸化チタン、炭酸カルシウム、カリオン、タルク、湿式または乾式シリカ、コロイド状シリカ、リン酸カルシウム、硫酸バリウム、アルミナおよびジルコニア等の無機粒子、アクリル酸類、スチレン等を構成成分とする有機粒子、ポリエステル重合反応時に添加する触媒等によって析出する、いわゆる内部粒子や、界面活性剤などがある。
【００３６】
本発明の二軸配向ポリエステルフィルムの用途は、特に限定されないが、磁気記録媒体用、コンデンサー用、感熱転写リボン用、感熱孔版印刷原紙用などに用いられる。
【００３７】
本発明の二軸配向ポリエステルフィルムの厚みは、特に限定されないが、１０００μｍ以下が好ましく、さらに好ましくは０．５〜５００μｍの範囲である。後述のように用途、目的に応じて適宜決定できるが、例えば、０．５〜２０μｍの範囲が好ましい。特に、磁気記録媒体用では、高密度磁気記録用テープ、例えば、データストレージ用のベースフィルムに適したものであり、該データ記録容量としては、好ましくは３０ＧＢ（ギガバイト）以上、より好ましくは７０ＧＢ以上、さらに好ましくは１００ＧＢ以上である。また、リニア記録密度としては、好ましくは２５キロバイト／ｃｍ以上、より好ましくは３４キロバイト／ｃｍ以上、さらにより好ましくは３９キロバイト／ｃｍ以上である。またフィルム厚みは、通常磁気記録材料用では１〜１５μｍ、データ用またはデジタルビデオ用塗布型磁気記録媒体用では２〜１０μｍ、データ用またはデジタルビデオ用蒸着型磁気記録媒体用では３〜９μｍの範囲が好ましい。また、コンデンサー用には、好ましくは０．５〜１５μｍのフィルムが適用され、絶縁破壊電圧および誘電特性の安定に優れたものとなる。熱転写リボン用途には、好ましくは１〜６μｍのフィルムが適用され、印字する際のしわがなく、印字むらやインクの過転写を生じることなく、項精細な印刷が行うことができる。感熱孔版原紙用途には、好ましくは０．５〜５μｍのフィルムが適用され、低エネルギーでの穿孔性にも優れ、エネルギーレベルに応じて穿孔径を変化させることが可能であり、複数版でのカラー印刷を行う場合などの印刷性にもすぐれている。
【００３８】
本発明の二軸配向ポリエステルフィルムは、これに他のポリマー層、例えば、ポリオレフィン、ポリアミド、ポリ塩化ビニリデンおよびアクリル系ポリマーを直接、あるいは接着剤などの層を介して積層してもよい。
【００３９】
本発明の二軸配向ポリエステルフィルムは、必要に応じて、熱処理、成形、表面処理、ラミネート、コーティング、印刷、エンボス加工、エッチングなどの任意の加工を行ってもよい。
【００４０】
本発明の二軸配向ポリエステルフィルムの製造方法は、押出機を用いた溶融押出により口金から吐出し、溶融ポリマーを冷却固化させて単一のガラス転移温度を有するシート状物を成形し、該シート状成形物を同時二軸テンターを用いて、二軸に延伸する二軸配向ポリエステルフィルムの製造方法において、ポリエステル（Ａ）とポリエーテルイミド（Ｂ）を溶融押出により相溶させて口金から吐出し、溶融ポリマーを冷却固化させてシート状に成形し、さらに、該シート状成型物を長手方向に１〜１０倍、幅方向に１〜１０倍の倍率で同時二軸テンターを用いて二軸に延伸し、しかる後に（ポリエステルフィルムのガラス転移温度）〜（ポリエステルフィルムの融点）の範囲内の温度で熱処理する二軸延伸ポリエステルフィルムの製造方法である。
【００４１】
より好ましい延伸条件は、長手方向に２〜９倍、幅方向に２〜９倍の倍率であり、さらに好ましい条件は、長手方向に３〜８倍、幅方向に３〜８倍の倍率である。ポリエステル（Ａ）とポリエーテルイミド（Ｂ）を相溶させる場合、ポリエーテルイミド（Ｂ）をポリエステル（Ａ）に添加する時期は、特に限定されないが、ポリエステルの重合前、例えば、エステル化反応前に添加してもよいし、重合後に溶融押出前に添加してもよい。中でも、溶融押出前に、ポリエステル（Ａ）とポリエーテルイミド（Ｂ）をペレタイズして、マスターチップにすることが溶融成形性の観点から好ましい。
【００４２】
本発明の二軸延伸ポリエステルフィルムの延伸形式としては、同時二軸テンターを用いていれば、長手方向に延伸した後に幅方向に延伸を行う方法などの一方向ずつの延伸を組み合わせた逐次二軸延伸法や、長手方向と幅方向を同時に延伸する同時二軸延伸法、さらに、逐次二軸延伸法と同時二軸延伸法を組み合わせた方法などが包含される。中でも、同時二軸延伸法を包含する方法が本発明の効果を得る上で、特に好ましい。
【００４３】
このような延伸方向や延伸倍率を自由に変更できる延伸機として、本発明ではリニアモーター方式の同時二軸テンターを使用することが好ましいと言える。
【００４４】
上述したように、リニアモーター式の同時二軸テンターは、
(1) 製膜速度、フィルム幅を従来の逐次二軸延伸並み、またはそれ以上に高めることができる、
(2) 高倍率延伸に対応できる、
(3) 延伸、熱処理、弛緩工程でのフィルムの変形パターンを自由に変更できる、等のことから近年注目を集めている。
【００４５】
本発明において、ポリエステルフィルムに対して延伸を施す場合の延伸温度は、特に限定されないが、未延伸フィルムに対して延伸を施す場合は、（ポリエステルフィルムのガラス転移温度（Ｔｇ））℃〜（Ｔｇ＋１２０）℃に保つことが好ましく、（Ｔｇ＋１０）℃〜（Ｔｇ＋８０）℃がより好ましい。 延伸温度がＴｇ℃未満では、延伸による配向が進みすぎて高倍率まで延伸しにくくなる。
【００４６】
本発明の二軸配向ポリエステルフィルムの製造方法の例について説明するが、これに限定されるものではない。ここでは、ポリエステル（Ａ）として、ポリエチレンテレフタレートを用い、ポリエーテルイミド（Ｂ）として、ポリエーテルイミド“ウルテム”を用いた例を示すが、用いるポリエステルやポリエーテルイミドにより製造条件は異なる。
【００４７】
まず、常法に従い、テレフタル酸とエチレングリコールからエステル化し、または、テレフタル酸ジメチルとエチレングリコールをエステル交換反応により、ビスーβ―ヒドロキシエチルテレフタレート（ＢＨＴ）を得る。次にこのＢＨＴを重合槽に移行しながら、真空下で２８０℃に加熱して重合反応を進める。ここで、固有粘度が０．５程度のポリエステルを得る。この時、所定量のポリエーテルイミドを添加しておいてもよい。得られたポリエステルをペレット状で減圧下において固相重合する。固相重合する場合は、あらかじめ１８０℃以下の温度で予備結晶化させた後、１９０〜２５０℃で１ｍｍＨｇ程度の減圧下、１０〜５０時間固相重合させる。また、フィルムを構成するポリエステルに粒子を含有させる方法としては、エチレングリコールに粒子を所定割合にてスラリーの形で分散させ、このエチレングリコールをテレフタル酸と重合させる方法が好ましい。粒子を添加する際には、例えば、粒子を合成時に得られる水ゾルやアルコールゾルを一旦乾燥させることなく添加すると粒子の分散性がよい。また、粒子の水スラリーを直接所定のポリエステルペレットと混合し、ベント式２軸混練押出機を用いて、ポリエステルに練り込む方法も有効である。粒子の含有量、個数を調節する方法としては、上記方法で高濃度の粒子のマスタを作っておき、それを製膜時に粒子を実質的に含有しないポリエステルで希釈して粒子の含有量を調節する方法が有効である。
【００４８】
次に、該ポリエチレンテレフタレートのペレット（Ａ）とポリエーテルイミドのペレット（Ｂ）を、一定の割合で混合して、２７０〜３００℃に加熱されたベント式の２軸混練押出機に供給して、溶融押出する。このときの剪断速度は５０〜３００ｓｅｃ^-1が好ましく、より好ましくは１００〜２００ｓｅｃ^-1、滞留時間は０．５〜１０分が好ましく、より好ましくは１〜５分の条件である。さらに、上記条件にて相溶しない場合は、得られたチップを再び二軸押出機に投入し相溶するまで押出を繰り返してもよい。上記混練によって、ポリエチレンテレフタレートとポリエーテルイミドは相溶し、ガラス転移点が単一のポリエステルのペレットを得ることができる。
【００４９】
得られたポリエーテルイミド含有のポリエステルのペレットを、１８０℃で３時間以上真空乾燥した後、固有粘度が低下しないように窒素気流下あるいは真空下で２８０〜３２０℃に加熱された押出機に供給し、従来から行われている方法により製膜する。また、異物や変質ポリマーを除去するために各種のフィルター、例えば、焼結金属、多孔性セラミック、サンド、金網などの素材からなるフィルターを用いることが好ましい。また、必要に応じて、定量供給性を向上させるためにギアポンプを設けてもよい。積層フィルムの場合には、２台以上の押出機、マニホールドまたは合流ブロックを用いて、溶融状態のポリエステルやポリエステルとポリエーテルイミドの混合物を積層したシートをスリット状のダイから押出し、キャスティングロール上で冷却して未延伸フィルムを作る。
【００５０】
次に、この未延伸フィルムを二軸延伸し、二軸配向させる。延伸方法としては、同時二軸テンターを用いて、逐次二軸延伸法または同時二軸延伸法を用いることができる。ここでは、長手方向と幅方向に同時に延伸を行う同時二軸延伸法を用いる。延伸温度については、ポリエステル（Ａ）やポリエーテルイミド（Ｂ）の構造成分や、積層の構成成分により異なるが、例えば、単層でポリエチレンテレフタレートとポリエーテルイミド“ウルテム”（登録商標）の混合ポリマーからなる場合を例示して説明する。未延伸フィルムを、リニアモーター方式の同時二軸延伸テンターに該フィルムの両端部をクリップで把持して導き、予熱ゾーンで９０〜１５０℃に加熱し、長手方向と幅方向のいずれにも同時に、１〜１０倍に１段もしくは２段以上の多段で延伸する。このときにいずれの場合も、フィルム端部を把持するクリップの温度は、８０〜１６０℃の温度範囲に設定するのが好ましい。延伸工程での延伸温度は、９０〜１５０℃の温度範囲内に保つことが好ましいが、いったん冷却して、フィルムの結晶化を抑えながら延伸してもかまわない。また、分子量が高い原料や結晶化しにくい原料の場合には、延伸温度を２００℃まで高めることも好ましく行うことができる。また、延伸工程の後半では、延伸温度を２段階以上で徐々に高めながら延伸することが好ましい。
【００５１】
続いて、二軸延伸されたポリエステルフィルムに平面性、寸法安定性を付与するために、１５０℃〜２５０℃、好ましくは、１７０〜２３０℃、さらに好ましくは１８０〜２２０℃の温度範囲で熱処理を施し、さらに、熱固定温度からの冷却過程で、好ましくは１００〜２２０℃の温度範囲で長手および幅方向に、好ましくは各方向に対して１〜６％の範囲で弛緩処理を行う。弛緩処理は１段でもよいし、多段で行ってもよく、温度分布の変化を設けてもよい。その後、フィルムを室温まで、必要ならば、長手および幅方向に弛緩処理を施しながら、フィルムを冷やして巻き取り、目的とする二軸配向ポリエステルフィルムを得る。
【００５２】
［物性の測定方法ならびに効果の評価方法］
特性値の測定方法ならびに効果の評価方法は次の通りである。
【００５３】
（１）広角Ｘ線回折法によるフィルムの結晶面回折ピークの円周方向の半価幅Ｘ線回折装置（（株）理学電機社製 ４０３６Ａ２型（管球型））を用いて下記の条件で、ディフラクトメータ法により測定した。
Ｘ線回折装置 （株）理学電機社製 ４０３６Ａ２型（管球型）
Ｘ線源 ：ＣｕＫα線（Ｎｉフィルター使用）
出力 ：４０ｋＶ ２０ｍＡ
ゴニオメータ （株）理学電機社製
スリット ：２ｍｍφ−１゜−１゜
検出器 ：シンチレーションカウンター
計数記録装置 （株）理学電機社製 ＲＡＤ−Ｃ型
２θ／θスキャンで得られた結晶面の回折ピーク位置に、２ｃｍ×２ｃｍに切り出して、方向をそろえて重ね合わせた試料およびカウンターを固定し、試料を面内回転させることにより円周方向のプロファイルを得る（βスキャン）。βスキャンで得られたピークプロファイルのうち、ピークの両端の谷部分をバックグランドとして、ピークの半値幅（ｄｅｇ）を計算した。
【００５４】
（２）広角Ｘ線回折法から得られる結晶サイズ
Ｘ線回折装置（（株）理学電機社製 ４０３６Ａ２型）を用いて下記の条件で、透過法により測定した。
Ｘ線回折装置 （株）理学電機社製 ４０３６Ａ２型
Ｘ線源 ：ＣｕＫα線（Ｎｉフィルター使用）
出力 ：４０ｋＶ ２０ｍＡ
ゴニオメータ （株）理学電機社製
スリット ：２ｍｍφ−１゜−１゜
検出器 ：シンチレーションカウンター
計数記録装置 （株）理学電機社製 ＲＡＤ−Ｃ型
２ｃｍ×２ｃｍに切り出して、方向をそろえて重ね合わせ、コロジオン・エタノール溶液で固めた試料をセットして、広角Ｘ線回折測定で得られた２θ／θ強度データのうち、各方向の面の半値幅から、下記のＳｃｈｅｒｒｅｒの式を用いて計算した。ここで結晶サイズは、配向主軸方向を測定した。
結晶サイズＬ（オングストローム）＝Ｋλ／β₀ｃｏｓθ_B
Ｋ ：定数（＝１．０）
λ ：Ｘ線の波長（＝１．５４１８オングストローム）
θ_B ：ブラッグ角
β₀＝（β_E ²−β_I ²）^1/2
β_E ：見かけの半値幅（実測値）
β_I ：装置定数（＝１．０４６×１０^-2）。
【００５５】
（３）補外ガラス転移開始温度（Ｔｇ-onset）、ガラス転移温度（Ｔｇ）
ＪＩＳ−Ｋ７１２１に従って、測定した。

なお、ＤＳＣ曲線においてガラス転移温度付近にショルダーが観測される場合は、ガラス転移温度を求めた後、ベースラインよりずれた部分の面積（単位ｍＪ／ｍｇ）を求め、５ｍＪ／ｍｇ以下の値であれば、単一のＴｇとした。
【００５６】
（４）ヤング率
ＡＳＴＭ−Ｄ８８２に規定された方法に従って、インストロンタイプの引張試験機を用いて測定した。測定は下記の条件とした。

（５）熱収縮率
ＪＩＳ−Ｃ２３１８に従って、測定した。
試料サイズ：幅１０ｍｍ、標線間隔２００ｍｍ
測定条件：温度１００℃、処理時間３０分、無荷重状態
１００℃熱収縮率を次式より求めた。
【００５７】
熱収縮率（％）＝［（Ｌ₀−Ｌ）／Ｌ₀］×１００
Ｌ₀：加熱処理前の標線間隔
Ｌ：加熱処理後の標線間隔。
【００５８】
（６）固有粘度
オルトクロロフェノール中、２５℃で測定した溶液粘度から下式から計算される値を用いる。すなわち、
ηｓｐ／Ｃ＝[η]＋Ｋ[η]２・Ｃ
ここで、ηｓｐ＝（溶液粘度／溶媒粘度）ー１、Ｃは溶媒１００ｍｌあたりの溶解ポリマ重量（ｇ／１００ｍｌ、通常１．２）、Ｋはハギンス定数（０．３４３とする）である。また、溶液粘度、溶媒粘度はオストワルド粘度計を用いて測定した。
【００５９】
（７）磁気テープの走行耐久性および保存性
本発明の二軸配向ポリエステルフィルムの表面に、下記組成の磁性塗料を塗布厚さ２．０μｍになるように塗布し、磁気配向させ、乾燥させる。次いで反対面に下記組成のバックコート層を形成した後、カレンダー処理した後、７０℃で、４８時間キュアリングする。上記テープ原反を１／２インチ幅にスリットし、磁気テープとして、長さ６７０ｍ分を、カセットに組み込んでカセットテープとした。
（磁性塗料の組成）
・強磁性金属粉末 ： １００重量部
・変成塩化ビニル共重合体 ： １０重量部
・変成ポリウレタン ： １０重量部
・ポリイソシアネート ： ５重量部
・ステアリン酸 ： １．５重量部
・オレイン酸 ： １重量部
・カーボンブラック ： １重量部
・アルミナ ： １０重量部
・メチルエチルケトン ： ７５重量部
・シクロヘキサノン ： ７５重量部
・トルエン ： ７５重量部
（バックコートの組成）
・カーボンブラック（平均粒径２０ｎｍ） ： ９５重量部
・カーボンブラック（平均粒径２８０ｎｍ）： １０重量部
・αアルミナ ： ０．１重量部
・変成ポリウレタン ： ２０重量部
・変成塩化ビニル共重合体 ： ３０重量部
・シクロヘキサノン ： ２００重量部
・メチルエチルケトン ： ３００重量部
・トルエン ： １００重量部
作成したカセットテープを、ＩＢＭ社製Ｍａｇｓｔａｒ３５９０ ＭＯＤＥＬＢ１Ａ Ｔａｐｅ Ｄｒｉｖｅを用い、１００回往復走行させ、次の基準でテープの走行耐久性を評価した。○が合格品とした。
○：テープ端面の伸び、折れ曲がりがなく、削れ跡が見られない。
【００６０】
△：テープ端面の伸び、折れ曲がりがないが、一部削れ跡が見られる。
【００６１】
×：テープ端面の一部が伸び、ワカメ状の変形が見られ、削れ跡が見られる。
【００６２】
また、上記作成したカセットテープをＩＢＭ社製Ｍａｇｓｔａｒ３５９０ ＭＯＤＥＬＢ１Ａ Ｔａｐｅ Ｄｒｉｖｅに、データを読み込んだ後、カセットテープを４０℃、８０％ＲＨの雰囲気中に１００時間保存した後、データを再生して次の基準で、テープの保存性を評価した。○が合格品とした。
○：トラックずれもなく、正常に再生した。
【００６３】
△：テープ幅に異常がないが、一部に読みとり不可が見られる。
【００６４】
×：テープ幅に変化があり、読みとり不可が見られる。
【００６５】
（８）フロッピーディスクの耐トラッキング性
Ａ．温度変化によるトラッキングずれテスト
トラッキングずれテストとしては、次のような方法を用いる。金属薄膜をスパッタ法により基材フィルムの両面に磁気記録層を形成してディスク状に打ち抜いた金属薄膜よりなるフロッピーディスクを温度１５℃、湿度６０％ＲＨでリングヘッドを用いて磁気記録し、そのときの最大出力と磁気シートの出力エンベロープを測定する。次に、雰囲気温度４０℃、湿度６０％ＲＨになるように維持して、その温度における最大出力と出力エンベロープを調べ、温度１５℃、湿度６０％ＲＨのときの出力エンベロープと、温度４０℃、湿度６０％ＲＨのときの出力エンベロープを比較して、トラッキングの状態を判定する。この差が小さいほど優れた耐トラッキング性を有している。この差が３ｄＢを超えるとトラッキングが×であり、３ｄＢ以内のものは○として評価した。
【００６６】
Ｂ．湿度変化によるトラッキングずれテスト
前項と同様にして作成したフロッピーディスクを温度２５℃、相対湿度２０％の雰囲気で記録し、さらに雰囲気条件を温度２５℃、相対湿度７０％に保持し、両条件における出力エンベロープを比較して、トラッキングの状態を判定する。前項と同様に、この差が３ｄＢを超えるとトラッキングが×であり、３ｄＢ以内のものは○として評価した。
【００６７】
（９）熱転写リボンの印字性
片面に融着防止層を塗布した本発明の熱転写リボン用ポリエステルフィルムに下記組成の熱転写インクを、塗布厚みが３．５μｍになるようにホットメルトコーターで融着防止層とは反対面に塗工し、熱転写リボンを作成した。
（熱転写インクの組成）
カルナウバワックス ：６０．６重量％
マイクロクリスタリンワックス ：１８．２重量％
酢酸ビニル・エチレン共重合体 ： ０．１重量％
カーボンブラック ：２１．１重量％
作成した熱転写リボンについて、オークス社製のバーコードプリンター（ＢＣ−８）で黒ベタを印字して、印字性を評価した。○が合格品とした。
○：鮮明に印字
△：印字にピッチずれが生じる
×：リボンにしわが入り、印字が乱れる
××：ホットメルト塗工時にフィルムにしわが入り、熱転写インクが均一に塗布できない。
【００６８】
（１０）コンデンサ用特性評価
絶縁抵抗および絶縁破壊電圧については以下の通りに評価した。
【００６９】
Ａ．絶縁抵抗
本発明のポリエステルフィルムの片面に表面抵抗値が２Ω／□となるようにアルミニウムを真空蒸着した。その際、長手方向に走るマージン部を有するストライプ状に蒸着した（蒸着部の幅５７ｍｍ、マージン部の幅３ｍｍの繰り返し）。次に各蒸着部の中央と各マージン部の中央に刃を入れてスリットし、左もしくは右に１．５ｍｍ幅のマージンを有する全幅３０ｍｍのテープ状の巻き取りリールとした。得られた左右対称のマージンを有するアルミ蒸着フィルム１対を重ね，１．５μＦの容量となる長さに巻回した。この巻回物を１２０℃、２０ｋｇ／ｃｍ² の圧力で１０分間プレスして成形した。両端面にメタリコンを溶射して電極とし、リード線を取り付けてコンデンサーサンプルとした。次いで、ここで作成した１．５μＦのコンデンサーサンプル１０００個を２３℃、６５％ＲＨの雰囲気下においてＹＨＰ社製の超絶縁抵抗計４３２９Ａにて印加電圧５００Ｖでの１分値として測定し、絶縁抵抗が５０００ＭΩ未満のコンデンサーサンプルを不良品として以下の基準で判定した。なお、本発明においては◎、○と△を合格とした。
◎：不良品が１０個未満
○：不良品が１０個以上２０個未満
△：不良品が２０個以上５０個未満
×：不良品が５０個以上。
【００７０】
Ｂ．絶縁破壊電圧
ＪＩＳ−Ｃ−２３１８に記載の方法に準じて、ただし、金属蒸着を施していないフィルムを試験片として用いて次のように評価する。
【００７１】
適当な大きさの金属製平板の上にゴムショア硬さ約６０度、厚さ約２ｍｍのゴム板を一枚敷き、その上に厚さ約６μｍのアルミニウム箔を１０枚重ねたものを下部電極とし、約５０ｇの重さで周辺に約１ｍｍの丸みを持った径８ｍｍの底面が平滑で傷のない黄銅製円柱を上部電極とする。試験片は、あらかじめ温度２０±５℃、相対湿度６５±５％の雰囲気に４８時間以上放置しておく。上部電極と下部電極の間に試験片をはさみこみ、温度２０±５℃、相対湿度６５±５％の雰囲気中で両電極間に直流電源により直流電圧を印加し、該直流電圧を１秒間に１００Ｖの速さで０Ｖから絶縁破壊するまで上昇させる。試料５０個に対し試験を行い、絶縁破壊電圧を試験片の厚みで除したものの平均値を求め、その値が４００Ｖ／μｍ以上を合格（○）とする。
【００７２】
【実施例】
次の実施例に基づき、本発明の実施形態を説明する。
【００７３】
実施例１
公知の方法により得られたポリエチレンテレフタレート（固有粘度０．８５）のペレットを５０重量％とポリエーテルイミドのペレット“ウルテム１０１０”（ジーイープラスチックス社 登録商標）５０重量％を、２８０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを５０重量％含有したポリエステルチップ(I)を得た。さらに、該チップ(I)４０重量％をポリエチレンテレフタレート（固有粘度０．６５、滑り剤として平均径０．３μｍの球状架橋ポリスチレン粒子０．２重量％と平均径０．８μｍの球状架橋ポリスチレン粒子０．０１重量％配合）のペレット６０重量％と混合し、２８０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを２０重量％含有したポリエステルチップ（II）を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【００７４】
一方、ポリエステルチップ(I)を４０重量％と、ポリエチレンテレフタレート（固有粘度０．６５、平均径０．０７μｍの球状シリカ粒子０．１６重量％配合）のペレットを６０重量％を、２８０℃に加熱されたベント式の２軸混練押出機に供給し、同様の方法で、ポリエステルチップ（III）を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【００７５】
押出機２台を用い、２８０℃に加熱された押出機Ａには、得られたポリエーテルイミド含有ポリエステル組成物（III）のペレットを１８０℃で３時間真空乾燥した後に供給し、同じく２８０℃に加熱された押出機Ｂには、得られたポリエーテルイミド含有ポリエステル組成物（II）のペレットを１８０℃で３時間真空乾燥した後に供給し、ポリエステル組成物（II）が最外層になるように３層積層するべくＴダイ中で合流させ（積層比II／III／II＝１／１０／１）、表面温度２５℃のキャストドラムに静電荷を印加させながら密着冷却固化し、積層未延伸フィルムを作成した。
【００７６】
この未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を１１０℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸する。続いて、フィルム温度を１５０℃にして、面積延伸倍率１．９６倍（縦倍率：１．４倍、横倍率：１．４倍）で同時二軸で再延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００７７】
この二軸配向ポリエステルフィルムの組成・特性等は、表１および表２に示したとおりであり、磁気記録媒体用などの各種用途のフィルムとして優れた特性を有している。
【００７８】
実施例２〜４
実施例１と同様にして、表１のようにポリエーテルイミドの含有量を変更して、ポリエーテルイミド含有ポリエステル組成物を得た後、実施例１と同様の方法で二軸配向ポリエステルフィルムを得る。
【００７９】
この二軸配向ポリエステルフィルムの特性は、表２に示したとおり、磁気記録媒体用などの各種用途のフィルムとして優れた特性を有している。
【００８０】
実施例５
実施例１と同様の方法で未延伸ポリエステルフィルムを得た後、該未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を１１０℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸する。さらに続いて、フィルム温度を１５０℃にして、長手方向に１．４倍に延伸し、続いて、幅方向に１．４倍に逐次に二軸再延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００８１】
この二軸配向ポリエステルフィルムの組成・特性等は、表１および表２に示したとおりであり、磁気記録媒体用などの各種用途のフィルムとして優れた特性を有している。
【００８２】
実施例６
公知の方法により得られたポリエチレン−２，６−ナフタレート（ＰＥＮ）（固有粘度０．６５、ガラス転移温度１２５℃、平均径０．３μｍの球状架橋ポリスチレン粒子０．２重量％と平均径０．８μｍの球状架橋ポリスチレン粒子０．０１重量％配合）のペレットを８０重量％とポリエーテルイミドのペレット“ウルテム１０１０”（ジーイープラスチックス社 登録商標）２０重量％を、２９０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを２０重量％含有したポリエステルチップ(IV)を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【００８３】
一方、ポリエチレン−２，６−ナフタレート（ＰＥＮ）（固有粘度０．６５、ガラス転移温度１２５℃、平均径０．０７μｍの球状シリカ粒子０．１６重量％配合）のペレットを８０重量％とポリエーテルイミドのペレット“ウルテム１０１０”（ジーイープラスチックス社 登録商標）２０重量％を、２９０℃に加熱されたベント式の２軸混練押出機に供給して、同様の方法で、ポリエーテルイミドを２０重量％含有したポリエステルチップ(V)を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【００８４】
押出機２台を用い、２９０℃に加熱された押出機Ａには、得られたポリエーテルイミド含有ポリエステル組成物（V）のペレットを１８０℃で３時間真空乾燥した後に供給し、同じく２９０℃に加熱された押出機Ｂには、得られたポリエーテルイミド含有ポリエステル組成物（IV）のペレットを１８０℃で３時間真空乾燥した後に供給し、ポリエステル組成物（IV）が最外層になるように３層積層するべくＴダイ中で合流させ（積層比IV／V／IV＝１／１０／１）、表面温度２５℃のキャストドラムに静電荷を印加させながら密着冷却固化し、積層未延伸フィルムを作成した。
【００８５】
この未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を１４５℃に加熱し、面積延伸倍率２５．０倍（縦倍率：５．０倍、横倍率：５．０倍）で同時二軸延伸する。続いて、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００８６】
この二軸配向ポリエステルフィルムの組成・特性等は、表１および表２に示したとおりであり、磁気記録媒体用などの各種用途のフィルムとして優れた特性を有している。
【００８７】
実施例７
実施例１と同様にして、ポリエーテルイミド含有ポリエステル組成物(III)を得た後、押出機２台を用い、２８０℃に加熱された押出機Ａには、該ポリエーテルイミド含有ポリエステル組成物（III）のペレットを１８０℃で３時間真空乾燥した後に供給し、同じく２８０℃に加熱された押出機Ｂには、ポリエチレンテレフタレート（ＰＥＴ）（VI）（固有粘度０．６５、ガラス転移温度７５℃、滑り剤として平均径０．３μｍの球状架橋ポリスチレン粒子０．２重量％と平均径０．８μｍの球状架橋ポリスチレン粒子０．０１重量％配合）のペレットを１８０℃で３時間真空乾燥した後に供給し、ポリエチレンテレフタレート（VI）が最外層になるように３層積層するべくＴダイ中で合流させ（積層比VI／III／VI＝１／１０／１）、表面温度２５℃のキャストドラムに静電荷を印加させながら密着冷却固化し、積層未延伸フィルムを作成した。
【００８８】
この未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を１０５℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸する。続いて、フィルム温度を１５０℃にして、面積延伸倍率１．９６倍（縦倍率：１．４倍、横倍率：１．４倍）で同時二軸で再延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００８９】
この二軸配向ポリエステルフィルムの組成・特性等は、表１および表２に示したとおりであり、磁気記録媒体用などの各種用途のフィルムとして優れた特性を有している。
【００９０】
実施例８
実施例１と同様にして、ポリエーテルイミド含有ポリエステル組成物(II)を得た後、押出機２台を用い、２８０℃に加熱された押出機Ａには、該ポリエーテルイミド含有ポリエステル組成物（II）のペレットを１８０℃で３時間真空乾燥した後に供給し、同じく２８０℃に加熱された押出機Ｂには、ポリエチレンテレフタレート（ＰＥＴ）（VII）（固有粘度０．６５、ガラス転移温度７５℃、平均径０．０７μｍの球状シリカ粒子０．１６重量％配合）のペレットを１８０℃で３時間真空乾燥した後に供給し、ポリエーテルイミド含有ポリエステル組成物（II）が最外層になるように３層積層するべくＴダイ中で合流させ（積層比II／VII／II＝１／１０／１）、表面温度２５℃のキャストドラムに静電荷を印加させながら密着冷却固化し、積層未延伸フィルムを作成した。
【００９１】
この未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を９５℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸する。続いて、フィルム温度を１５０℃にして、面積延伸倍率１．９６倍（縦倍率：１．４倍、横倍率：１．４倍）で同時二軸で再延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００９２】
この二軸配向ポリエステルフィルムの組成・特性等は、表１および表２に示したとおりであり、磁気記録媒体用などの各種用途のフィルムとして優れた特性を有している。
【００９３】
比較例１
３層積層(II/III/II)において、３層ともポリエーテルイミドが混合されていないポリエチレンテレフタレート（ＰＥＴ）にすること以外は、実施例１と同様にして未延伸フィルムを作成する。
【００９４】
この未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を９０℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸する。続いて、フィルム温度を１５０℃にして、面積延伸倍率１．９６倍（縦倍率：１．４倍、横倍率：１．４倍）で同時二軸で再延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００９５】
この二軸配向ポリエステルフィルムは、ポリイミドエーテルを含有していておらず、その組成・特性等は、表１および表２に示したとおり、磁気記録媒体用などの各種用途のフィルムとして劣るものであった。
【００９６】
比較例２
実施例１と同様にして得た未延伸ポリエステルフィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を１１０℃に加熱し、長手方向に３．１倍に延伸し、続いて、幅方向に３．５倍に逐次二軸延伸する。さらに続いて、フィルム温度を１５０℃にして、長手方向に１．４倍延伸し、さらに幅方向に１．４倍延伸する。定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ５μｍの二軸延伸ポリエステルフィルムを得る。
【００９７】
このポリエステルフィルムは、表１に示したとおり、結晶配向解析による半値幅が本発明の範囲外であり、その特性は、表２に示したとおり、磁気記録媒体用などの各種用途のフィルムとして劣るものであった。
【００９８】
比較例３
実施例１と同様にして得た未延伸ポリエステルフィルムを、ロール式延伸機にて長手方向に１段で、温度１１０℃で３．２倍延伸し、さらに、テンターを用いて、幅方向に温度１００℃で３．８倍延伸した。続いて、ロール式延伸機で長手方向に２段で、温度１３５℃で１．５倍に再延伸し、テンターを用いて幅方向に温度２００℃で１．４倍再延伸した。定長下で温度２１０℃で１０秒間熱処理後、幅方向に２％の弛緩処理を行い、厚さ５μｍの二軸配向ポリエステルフィルムを得た。
【００９９】
このポリエステルフィルムは、表１に示したとおり、結晶配向解析による半値幅が本発明の範囲外であり、その特性は、表２に示したとおり、磁気記録媒体用などの各種用途のフィルムとして劣るものであった。
【０１００】
実施例９
実施例１と同様にして得た５０重量％のポリエーテルイミド含有ポリエステルチップ(I)を４０重量％と、ポリエチレンテレフタレート（固有粘度０．６５,平均径０．３μｍの球状架橋ポリスチレン粒子６重量％配合）のペレット６０重量％と混合し、２８０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを２０重量％含有したポリエステルチップ（VIII）を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【０１０１】
一方、実施例１と同様にして得た５０重量％のポリエーテルイミド含有ポリエステルチップ(I)を４０重量％と、ポリエチレンテレフタレート（固有粘度０．６５、粒子なし）のペレット６０重量％と混合し、２８０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを２０重量％含有したポリエステルチップ（IX）を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【０１０２】
押出機２台を用い、２８０℃に加熱された押出機Ａには、ポリエーテルイミド含有ポリエステルチップ(VIII)のペレットを１８０℃で３時間真空乾燥した後に供給し、同じく２８０℃に加熱された押出機Ｂには、ポリエーテルイミド含有ポリエステルチップ（IX）のペレットを１８０℃で３時間真空乾燥した後に供給し、Ｔダイ中で合流し（積層比VIII／IX＝１／２５０）、表面温度２５℃のキャストドラムに静電密着させて、冷却固化し、未延伸フィルムを作成する。得られた未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を１１０℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ７５μｍの二軸延伸ポリエステルフィルムを得る。得られた二軸配向ポリエステルフィルムに磁気記録媒体用の加工を施して、フロッピーディスクとしての実用特性を評価する。結果は、表３のとおり、優れた特性を有している。
【０１０３】
比較例４
押出機２台を用い、２８０℃に加熱された押出機Ａには、ポリエチレンテレフタレート（固有粘度０．６５,平均径０．３μｍの球状架橋ポリスチレン粒子６重量％配合）のペレットを１８０℃で３時間真空乾燥した後に供給し、同じく２８０℃に加熱された押出機Ｂには、ポリエチレンテレフタレート（固有粘度０．６５、粒子なし）のペレットを１８０℃で３時間真空乾燥した後に供給し、Ｔダイ中で合流し（積層比Ａ／Ｂ＝１／２５０）、表面温度２５℃のキャストドラムに静電密着させて、冷却固化し、未延伸フィルムを作成する。
【０１０４】
得られた未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、フィルム温度を９５℃に加熱し、面積延伸倍率１２．２５倍（縦倍率：３．５倍、横倍率：３．５倍）で同時二軸延伸し、定長下で温度２１０℃で１０秒間熱処理後、縦横各方向に２％の弛緩処理を行い、厚さ７５μｍの二軸延伸ポリエステルフィルムを得る。
【０１０５】
得られた二軸配向ポリエステルフィルムに磁気記録媒体用の加工を施して、フロッピーディスクとしての実用特性を評価する。結果は、表３のとおり、実用特性に劣るものである。
【０１０６】
実施例１０
実施例１と同様にして得た５０重量％のポリエーテルイミド含有ポリエステルチップ(I)を４０重量％と、ポリエチレンテレフタレート（固有粘度０．６５、平均径１．０μｍの二酸化ケイ素粒子０．２重量％配合）のペレット６０重量％と混合し、２８０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを２０重量％含有したポリエステルチップ（X）を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【０１０７】
該ポリエステルチップ(X)を１８０℃で３時間真空乾燥した後に、２８０℃に加熱された押出機に供給して溶融押出し、Ｔダイよりシート状に吐出する。さらにこのシートを表面温度２５℃の冷却ドラム上に静電気力で密着させて冷却固化し、未延伸フィルムを得る。この未延伸フィルムの片面に融着防止層として下記組成の塗剤を乾燥後の塗布厚みが０．５μｍになるようにグラビアコーターで塗工する。
（塗剤の組成）
アクリル酸エステル ：１４．０重量％
アミノ変性シリコーン ： ５．９重量％
イソシアネート ： ０．１重量％
水 ：８０．０重量％
その後、得られた未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、実施例１と同様の延伸条件で製造する。得られた厚さ４μｍのフィルムに熱転写リボン用加工を施して、熱転写リボン用としての実用特性を評価する。結果は、表４のとおり、優れた特性を有している。
【０１０８】
比較例５
実施例１０において、ポリエーテルイミドを含有しないポリエチレンテレフタレートを用いて、比較例１と同様に延伸して、二軸配向ポリエステルフィルムを得る。得られた厚さ４μｍのフィルムに熱転写リボン用加工を施して、熱転写リボン用としての実用特性を評価する。結果は、表４のとおり、実用特性に劣るものである。
【０１０９】
実施例１１
実施例１と同様にして得た５０重量％のポリエーテルイミド含有ポリエステルチップ(I)を４０重量％と、ポリエチレンテレフタレート（固有粘度０．６５、平均径１．２μｍの凝集シリカ粒子０．１重量％配合）のペレット６０重量％と混合し、２８０℃に加熱されたベント式の２軸混練押出機に供給して、剪断速度１００ｓｅｃ^-1、滞留時間１分にて溶融押出し、ポリエーテルイミドを２０重量％含有したポリエステルチップ（XI）を得た。得られたチップは透明であり、単一のガラス転移温度しか観測されなかった。
【０１１０】
該ポリエステルチップ(XI)を１８０℃で３時間真空乾燥した後に、２８０℃に加熱された押出機に供給して溶融押出し、Ｔダイよりシート状に吐出する。さらにこのシートを表面温度２５℃の冷却ドラム上に静電気力で密着させて冷却固化し、未延伸フィルムを得る。この未延伸フィルムの両端部をクリップで把持して、リニアモーター方式の同時二軸延伸テンターに導き、実施例１と同様の延伸条件で製造した厚さ４μｍのフィルムを、コンデンサー用に加工を施して、実用特性を評価する。結果は、表５のとおり、優れた特性を有している。
【０１１１】
比較例６
実施例１１において、ポリエーテルイミドを含有しないポリエチレンテレフタレートを用いて、比較例１と同様に延伸して、二軸配向ポリエステルフィルムを得る。得られた厚さ４μｍのフィルムを、コンデンサー用に加工を施して、実用特性を評価する。結果は、表５のとおり、実用特性に劣るものである。
【０１１２】
【表１】

【表２】

【表３】

【表４】

【表５】

【発明の効果】
本発明によれば、フィルムのヤング率などの機械特性や寸法安定性を向上させた二軸配向ポリエステルフィルムを得ることができる。磁気記録媒体用、コンデンサー用、感熱転写リボン用、感熱孔版印刷用原紙用などの各種フィルム用途に広く活用が可能である。具体的には、磁気記録媒体用として、走行耐久性、保存性、フロッピー用耐トラッキング性などに優れ、さらに、感熱転写リボン用として印字性に優れたベースフィルムを得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biaxially oriented polyester film in which the properties and quality of a conventional polyester film are greatly improved and a method for producing the same.
[0002]
Specifically, it is excellent in rigidity, toughness, dimensional stability, etc., and is very suitable as a film for various industrial materials such as magnetic recording media, condensers, thermal transfer ribbons, and heat sensitive stencil printing base papers. The present invention relates to a biaxially oriented polyester film and a method for producing the film.
[0003]
[Prior art]
Polyester film is capable of continuous production of large-area films that cannot be obtained from other materials, taking advantage of its strength, durability, transparency, flexibility, and surface characteristics. It is used in various fields where there is a great demand for various industrial materials such as magnetic recording media, condensers, thermal transfer ribbons, and heat-sensitive stencil printing base papers, agriculture, packaging, and building materials.
[0004]
Among them, the biaxially oriented polyester film is used in various fields from the viewpoint of mechanical properties and dimensional stability, and is particularly useful as a base film for a magnetic recording medium. For magnetic recording media, in particular, in recent years, there has been a demand for further reduction in the thickness of the base film in order to reduce the weight, size, and recording time of equipment. In recent years, the trend toward thin films has been very strong for thermal transfer ribbons, condensers, and heat-sensitive stencil sheets.
[0005]
However, when the film is thinned, the mechanical strength becomes insufficient, and the stiffness of the film becomes weaker or it becomes easier to stretch. For example, for magnetic recording media, it is easily damaged by tape. Or the head touch deteriorates and the electromagnetic conversion characteristics deteriorate. In addition, when the film is made thin, the flatness of the ribbon at the time of printing is not maintained for the thermal transfer ribbon, printing unevenness and overtransfer occur, and the dielectric breakdown voltage decreases for the capacitor. There is.
[0006]
In such thin film orientation, higher strength is desired by improving mechanical properties such as tensile properties represented by Young's modulus.
[0007]
Therefore, increasing the strength of the film has been studied conventionally by various methods. As a generally known technique for increasing the strength of a biaxially stretched polyester film, for example, a film stretched in two longitudinal and lateral directions is stretched again in the longitudinal direction to increase the strength in the longitudinal direction. The stretching method is common (for example, Japanese Patent Publication No. 42-9270, Japanese Patent Publication No. 43-3040, Japanese Patent Publication No. 46-1119, Japanese Patent Publication No. 46-1120, etc.).
[0008]
Further, when it is desired to impart strength also in the transverse direction, there has been proposed a re-longitudinal re-lateral stretching method in which the above-mentioned re-longitudinal stretching is performed and then the transverse direction is stretched again (for example, JP-A-50 -133276, JP-A-55-22915, etc.). Further, there has been proposed a longitudinal multi-stage stretching method in which the first-stage stretching is performed in two or more stages in the longitudinal direction of the film and subsequently the film is stretched in the transverse direction (for example, Japanese Patent Publication No. 52-33666, Japanese Patent Publication No. Sho). 57-493377 etc.).
[0009]
However, the high-strength polyester film obtained by such a conventional technique, for example, for magnetic recording media, changes in dimensions due to stress elongation deformation or environmental conditions, and a recording track is displaced, and an error occurs during recording and reproduction. Therefore, there is a problem that a desired electromagnetic conversion characteristic cannot be obtained, and there are still problems in application to a large-capacity high-density magnetic recording tape.
[0010]
On the other hand, the composition of polyester and polyimide has been described in the past, for example, polyethylene terephthalate (PET) is used as polyester, while polyetherimide (PEI) which is one kind of thermoplastic polyimide is used as polyimide. It has been shown that the composition of various mixing ratios used increases the glass transition temperature with increasing PEI weight fraction (eg, “JOURNAL of APPLIED POLYMER SCIENCE”, 1993, Vol. 48). 935-937, “Macromolecules” 1995, 28, 2845-2851, “POLYMER 1997, 38, 4043-4048”, etc.). However, there has been no report on a film made of a mixture of PET and PEI, and furthermore, the mechanical properties and dimensional stability of the film are not known at all and are not studied.
[0011]
Further, in recent years, a linear motor type simultaneous biaxial tenter has been developed and attracts attention because of its high film forming speed (for example, Japanese Patent Publication No. 51-33590, US Pat. No. 4,853,602, US Pat. No. 4,675,582).
[0012]
In other words, the conventional simultaneous biaxial stretching method, which is a screw method in which a clip is placed in a screw groove to widen the clip interval, or a pantograph method in which the clip interval is widened using a pantograph, is manufactured. There were problems such as a slow film speed, a condition change such as a draw ratio that was not easy, and a high-strength stretch that was not easy. On the other hand, the linear motor type simultaneous biaxial stretching method may solve these problems all at once.
[0013]
Japanese Patent Publication No. 51-33590 described above discloses that high-efficiency production is possible by changing the tenter clip interval by an electric force generated by a linear motor. Also, the above-mentioned US Pat. No. 4,853,602 discloses a stretching system using a linear motor, and the above-mentioned US Pat. No. 4,675,582 controls a number of linear motors along the stretching section. An effective system is disclosed. However, these US patents do not mention the high-quality polyester film obtained in the present invention.
[0014]
[Problems to be solved by the invention]
An object of the present invention is to provide a high-quality biaxially oriented polyester film excellent in mechanical strength such as Young's modulus and dimensional stability, and a method for producing the same, particularly when used as a base film for a magnetic recording medium. In addition, a biaxially oriented polyester film excellent in storage stability and running durability, suitable for a base film for high-density magnetic recording tape, and suitable for a floppy, a thermal transfer ribbon, and a capacitor, and its production method Is to provide.
[0015]
[Means for Solving the Problems]
  The biaxially oriented polyester film of the present invention that meets the above-mentioned object is a biaxially oriented polyester film having a single glass transition temperature comprising polyester (A) and polyetherimide (B), which is a wide-angle X-ray. The half-value width in the circumferential direction of the diffraction peak of the crystal plane in the biaxially oriented polyester main chain direction obtained when the film is rotated about the normal line in the crystal orientation analysis by diffraction diffractometer method is 55 to 85 Is a range of degreesBiaxially oriented polyester film stretched simultaneously biaxiallyIt is characterized by being.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The polyester (A) constituting the biaxially oriented polyester film of the present invention is composed of, for example, an acid component such as an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid or an aliphatic dicarboxylic acid, or a diol component.
[0017]
Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-diphenyldicarboxylic acid. Acid, 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, and the like can be used. Among them, terephthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid can be preferably used. . As the alicyclic dicarboxylic acid component, for example, cyclohexane dicarboxylic acid or the like can be used. As the aliphatic dicarboxylic acid component, for example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be used. These acid components may be used alone or in combination of two or more.
[0018]
Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2′-bis (4 '-Β-hydroxyethoxyphenyl) propane and the like can be used, and among them, ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol and the like can be used, and particularly preferably. Use ethylene glycol, etc. Can do. These diol components may be used alone or in combination of two or more.
[0019]
The polyester may be copolymerized with a monofunctional compound such as lauryl alcohol or phenyl isocyanate, trimellitic acid, pyromellitic acid, glycerol, pentaerythritol, 2,4-dioxybenzoic acid, or the like. Trifunctional compounds and the like may be copolymerized within a range in which the polymer is substantially linear without excessive branching or crosslinking. In addition to the acid component and diol component, the present invention includes aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid, m-hydroxybenzoic acid, and 2,6-hydroxynaphthoic acid, p-aminophenol, and p-aminobenzoic acid. As long as the effect is not impaired, the copolymerization can be further carried out.
[0020]
The polyester (A) of the present invention is not particularly limited, but from the viewpoint of mechanical strength, productivity and handleability, etc., a polyester mainly composed of ethylene terephthalate and / or ethylene-2,6-naphthalenedicarboxylate unit and It is preferably at least one selected from the group consisting of these modified products. Among these, polyesters containing 80% by weight or more of ethylene terephthalate units are particularly desirable. This is because a polyester having an ethylene terephthalate unit as a main constituent is easier to extrude than a polyester having an ethylene-2,6-naphthalenedicarboxylate unit as a main constituent and the film is broken during film formation. Because there are few. However, the latter has the advantage of good compatibility with polyetherimide.
[0021]
The polyetherimide (B) of the present invention is not particularly limited, but from the viewpoint of melt moldability and handleability with the polyester (A), for example, as shown by the following general formula, an ether bond to a polyimide constituent component It is preferable that it is a structural unit containing.
[Chemical 1]

However, in the above formula, R₁Is a divalent aromatic or aliphatic residue having 6 to 30 carbon atoms; R₂Is a divalent aromatic residue having 6 to 30 carbon atoms, an alkylene group having 2 to 20 carbon atoms, a cycloalkylene group having 2 to 20 carbon atoms, and 2 to 8 carbons A divalent organic group selected from the group consisting of polydiorganosiloxane groups chain-terminated with alkylene groups having atoms.
[0022]
R above₁, R₂As, for example, an aromatic residue represented by the following formula group
[Chemical 2]

Can be mentioned.
[0023]
In the present invention, 2,2-bis [4- (2,3-dicarboxyphenoxy) having a structural unit represented by the following formula from the viewpoints of compatibility with polyester (A), cost, melt moldability and the like. A condensation product of phenyl] propane dianhydride and m-phenylenediamine or p-phenylenediamine is preferred.
[Chemical Formula 3]

This polyetherimide is available from GE Plastics under the trade name “Ultem” (registered trademark).
[0024]
The term “compatible” as used herein can be determined by the single chip having a single glass transition temperature (Tg). . Thus, it is generally known that Tg when both are compatible exists between Tg of polyethylene terephthalate (A) and Tg of polyetherimide pellet (B). Note that having a single glass transition temperature (Tg) means that, literally, only one Tg is recognized and no other Tg or the equivalent is recognized. Even if a heat flux gap-like material other than the Tg heat flux gap is recognized, it is ignored if the heat flux gap is 1/10 or less of the Tg, and a single glass is used. It is considered to have a dislocation point temperature (Tg). Moreover, even if there is a shoulder of 5 mJ / mg or less near the glass transition temperature, it is regarded as having a single Tg. In the present invention, a biaxially oriented polyester film having a single glass transition temperature indicates that at least one layer of the film has such a property. Therefore, films having different glass transition points may be laminated on the film of the present invention as long as the effects of the invention are not hindered. However, if the glass transition point between the laminated layers is too different, film production becomes difficult. Therefore, the difference in glass transition point is preferably 50 ° C. or less, and more preferably 30 ° C. or less. However, it goes without saying that the coating layer is not limited to this.
[0025]
In the present invention, the time when the polyetherimide (B) is added to the polyester (A) is not particularly limited, but may be added before the polymerization of the polyester, for example, before the esterification reaction, or after the polymerization and before the melt extrusion. You may add to. Moreover, you may pelletize polyester (A) and polyetherimide (B) before melt extrusion.
[0026]
In the biaxially oriented polyester film of the present invention, the biaxially oriented polyester main chain direction obtained when the biaxially oriented polyester film is rotated about the normal as a result of crystal orientation analysis by a diffractometer method of wide-angle X-ray diffraction It is essential that the half-value width in the circumferential direction of the diffraction peak of the crystal plane is in the range of 55 to 85 degrees. The half-value width in the circumferential direction of the diffraction peak of the crystal plane in the polyester main chain direction represents the spread of the distribution in the direction of crystal orientation of the biaxially oriented polyester film, and when this half-value width is less than 55 degrees, The dimensional stability of the film is inferior and the storage stability is deteriorated, or the tear propagation resistance of the film is reduced and tape breakage is likely to occur. On the other hand, when the half width exceeds 85 degrees, a film having high strength in all directions in the plane of the film cannot be obtained, and the object of the present invention cannot be achieved. Here, the crystal plane in the polyester main chain direction is a crystal plane whose normal is closest to the polyester main chain direction among crystal planes detected as diffraction peaks by the wide-angle X-ray diffractometer method, for example, Polyethylene terephthalate has a (−105) plane, and polyethylene-2,6-naphthalate has a (−306) plane. The half width is more preferably in the range of 60 to 85 degrees, and most preferably in the range of 65 to 80 degrees for obtaining the effects of the present invention.
[0027]
In the biaxially oriented film of the present invention, the crystal size in the polyester main chain direction obtained from the wide-angle X-ray diffraction method is not particularly limited, but is preferably in the range of 40 angstroms to 90 angstroms. Here, the polyester main chain direction is the normal direction of the crystal plane closest to the polyester main chain direction, for example, (−105) plane for polyethylene terephthalate and (−306) for polyethylene-2,6-naphthalate. The normal direction of the surface. If the crystal size is less than 40 angstroms, the elongation deformation of the tape becomes large, edge damage is likely to occur, and the storage stability after tape processing deteriorates. Further, when the crystal size exceeds 90 angstroms, the frequency of tape breakage may increase. The crystal size varies depending on the polyester used, but in the case of polyethylene terephthalate, a range of 45 angstroms to 85 angstroms is more preferable, and a range of 50 angstroms to 80 angstroms is more preferable. When the polyester used is polyethylene-2,6-naphthalate, the range of 50 angstroms to 65 angstroms is more preferable.
[0028]
The content of the polyetherimide (B) in the biaxially oriented polyester film of the present invention is not particularly limited, but is preferably in the range of 1 to 50% by weight. More preferably, it is the range of 5-30 weight%, More preferably, it is the range of 10-25 weight%. Since the melt viscosities of polyester (A) and polyetherimide (B) are greatly different, if the content of polyetherimide (B) is less than 1% by weight, sufficient kneading is obtained in an extruder and they are compatible with each other. It may be difficult to do. Further, if the content of the polyetherimide (B) exceeds 50% by weight, the extrusion process may be difficult, and in order to express sufficient strength in the obtained polyester film, stretching is performed. It may be difficult to process.
[0029]
The sum of the Young's modulus in the longitudinal direction and the Young's modulus in the width direction of the biaxially oriented polyester film of the present invention is not particularly limited, but is preferably in the range of 10 to 25 GPa, more preferably 12 to 22 GPa, even more preferably. 14-20 GPa. If the sum of the Young's moduli is less than 10 GPa, for example, when used for a magnetic recording medium, the magnetic tape is easily stretched and deformed due to the tension received from the magnetic recording head and guide pins during running, and the electromagnetic The conversion characteristics (output characteristics) may be adversely affected and may not be practically usable. In addition, a film having a sum of Young's modulus exceeding 25 GPa may be difficult to produce industrially, and the tear resistance and dimensional stability of the film may be significantly reduced.
[0030]
The heat shrinkage rate in the longitudinal direction and the width direction of the biaxially oriented polyester film of the present invention at 100 ° C. for 30 minutes is not particularly limited, but from the viewpoint of the stretch deformability and storage stability of the tape, all are 0.01 to It is preferably 2.0%. More preferably, it is 0.01 to 1.5%, and still more preferably 0.01 to 1.0%. When the heat shrinkage rate at a temperature of 100 ° C. exceeds 2.0%, the dimensional stability may be easily lost. For example, in the case of a magnetic recording medium, a film processing step such as coating a magnetic layer of a base film. When the temperature of the magnetic tape rises due to the heat history and frictional heat between the magnetic tape and the magnetic recording head during running, the tape is likely to be thermally deformed, and the storage stability of the tape may be deteriorated. Moreover, when the heat shrinkage rate at a temperature of 100 ° C. is less than 0.01%, the film may expand and wrinkles may occur.
[0031]
The biaxially oriented polyester film of the present invention is not particularly limited, but when it contains a component comprising a polyester (A) and a polyetherimide (B) mainly composed of an ethylene terephthalate unit, its extrapolated glass transition start temperature ( Tg-onset) is preferably 90 to 150 ° C. Tg-onset is more preferably in the range of 95 to 130 ° C, more preferably 100 to 120 ° C. If Tg-onset is less than 90 ° C., the effect of the present invention may be small for improving the dimensional stability of the film. Moreover, if Tg-onset is a temperature exceeding 150 ° C., it may be inferior in terms of molding such as melt moldability and stretch processability.
[0032]
The biaxially oriented polyester film of the present invention may be a single layer or a laminated structure of two or more layers. Although not particularly limited, it is more preferable to have a laminated structure of two or more layers. When it is a single layer, for example, when it is used for a magnetic recording medium, if particles are contained, the projections on the surface are not aligned, and electromagnetic conversion characteristics and runnability may deteriorate. Further, the case of three layers is preferable because the effect of the present invention becomes even better. The thickness of the outermost layer is not particularly limited, but is preferably 0.1 to 10 times the average diameter of the particles contained in the outermost layer because the effects of the present invention are further improved. This is because if the lower limit value of this range is not reached, the electromagnetic conversion characteristics may be poor, whereas if the upper limit value of this range is exceeded, the running performance may be poor. Moreover, when making it laminate | stack, at least 1 layer consists of polyester (A) and polyetherimide (B) in the laminated structure of two or more layers. The other layers are not particularly limited, but polyesters are preferably exemplified, and the polyesters are not particularly limited, but include ethylene terephthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxy. Particularly preferred is a case where at least one structural unit selected from a rate or an ethylene 2,6-naphthalate unit is used as a main constituent.
[0033]
When a layer composed of polyester (A) and polyetherimide (B) is arranged in the inner layer, effects such as storage stability and improvement in tensile strength can be obtained. In that case, the thickness is preferably 80% or more of the total thickness. Moreover, when arranged in the outer layer, it is effective in improving running durability. In that case, the thickness is preferably 0.1 μm or more.
[0034]
The intrinsic viscosity of the polyester (A) of the present invention is not particularly limited, but is 0.55 to 3.0 (dl / g) from the viewpoint of stability of film forming processing and miscibility with the polyetherimide (B). It is preferable that it is the range of this, More preferably, it is 0.60-2.0 (dl / g). In addition, the intrinsic viscosity of the biaxially oriented polyester film is not particularly limited, but may be in the range of 0.50 to 2.0 (dl / g) from the viewpoints of film forming stability and dimensional stability. More preferably, it is 0.55-1.0 (dl / g).
[0035]
The biaxially oriented polyester film of the present invention is an organic lubricant such as a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a pigment, a dye, a fatty acid ester, and a wax within the range not inhibiting the present invention. Etc. may be added. In addition, adding inorganic particles, organic particles, etc. to the outermost layer of the laminated film in order to impart easy slipping, abrasion resistance, scratch resistance, etc. to the film surface is useful, for example, for magnetic recording media. is there. Examples of the additive include clay, mica, titanium oxide, calcium carbonate, carion, talc, wet or dry silica, colloidal silica, calcium phosphate, barium sulfate, alumina, zirconia, and other inorganic particles, acrylic acids, styrene, and the like. Organic particles, so-called internal particles that are precipitated by a catalyst added during the polyester polymerization reaction, and surfactants.
[0036]
Although the use of the biaxially oriented polyester film of the present invention is not particularly limited, it is used for magnetic recording media, capacitors, thermal transfer ribbons, thermal stencil printing base papers, and the like.
[0037]
Although the thickness of the biaxially oriented polyester film of this invention is not specifically limited, 1000 micrometers or less are preferable, More preferably, it is the range of 0.5-500 micrometers. Although it can determine suitably according to a use and the objective as mentioned later, the range of 0.5-20 micrometers is preferable, for example. Particularly for magnetic recording media, it is suitable for high-density magnetic recording tape, for example, a base film for data storage, and the data recording capacity is preferably 30 GB (gigabytes) or more, more preferably 70 GB or more. More preferably, it is 100 GB or more. The linear recording density is preferably 25 kilobytes / cm or more, more preferably 34 kilobytes / cm or more, and even more preferably 39 kilobytes / cm or more. The film thickness is usually in the range of 1 to 15 μm for magnetic recording materials, 2 to 10 μm for data or digital video coated magnetic recording media, and 3 to 9 μm for data or digital video vapor deposition magnetic recording media. Is preferred. Further, a film having a thickness of 0.5 to 15 μm is preferably used for the capacitor, and the dielectric breakdown voltage and the stability of the dielectric characteristics are excellent. A film having a thickness of 1 to 6 μm is preferably used for the thermal transfer ribbon application, and there is no wrinkle at the time of printing, and fine printing can be performed without causing printing unevenness and ink overtransfer. For heat-sensitive stencil paper use, a film of 0.5 to 5 μm is preferably applied, and it has excellent perforation property at low energy, and the perforation diameter can be changed according to the energy level. Excellent printability when performing color printing.
[0038]
The biaxially oriented polyester film of the present invention may be laminated with another polymer layer such as polyolefin, polyamide, polyvinylidene chloride and acrylic polymer directly or via a layer such as an adhesive.
[0039]
The biaxially oriented polyester film of the present invention may be subjected to any processing such as heat treatment, molding, surface treatment, laminating, coating, printing, embossing, etching, etc. as necessary.
[0040]
The method for producing a biaxially oriented polyester film according to the present invention comprises forming a sheet having a single glass transition temperature by discharging from a die by melt extrusion using an extruder, and cooling and solidifying the molten polymer. In a method for producing a biaxially oriented polyester film that is biaxially stretched using a simultaneous biaxial tenter, polyester (A) and polyetherimide (B) are mixed by melt extrusion and discharged from a die. The molten polymer is cooled and solidified to form a sheet, and the sheet-shaped product is biaxially formed using a simultaneous biaxial tenter at a magnification of 1 to 10 times in the longitudinal direction and 1 to 10 times in the width direction. A method for producing a biaxially stretched polyester film that is stretched and then heat-treated at a temperature within the range of (glass transition temperature of the polyester film) to (melting point of the polyester film). A.
[0041]
More preferable stretching conditions are 2 to 9 times in the longitudinal direction and 2 to 9 times in the width direction, and further preferable conditions are 3 to 8 times in the longitudinal direction and 3 to 8 times in the width direction. . When the polyester (A) and the polyetherimide (B) are compatible, the timing of adding the polyetherimide (B) to the polyester (A) is not particularly limited, but before polyester polymerization, for example, before the esterification reaction Or may be added after polymerization but before melt extrusion. Among these, it is preferable from the viewpoint of melt moldability to pelletize the polyester (A) and the polyetherimide (B) to form a master chip before melt extrusion.
[0042]
As a stretching type of the biaxially stretched polyester film of the present invention, if a simultaneous biaxial tenter is used, a sequential biaxial combination of stretching in each direction, such as a method of stretching in the width direction after stretching in the longitudinal direction Examples include a stretching method, a simultaneous biaxial stretching method in which the longitudinal direction and the width direction are simultaneously stretched, and a method in which a sequential biaxial stretching method and a simultaneous biaxial stretching method are combined. Among these, a method including a simultaneous biaxial stretching method is particularly preferable in obtaining the effects of the present invention.
[0043]
It can be said that it is preferable to use a linear motor type simultaneous biaxial tenter as a stretching machine capable of freely changing the stretching direction and the stretching ratio.
[0044]
As mentioned above, the linear motor type simultaneous biaxial tenter is
(1) The film-forming speed and film width can be increased to the same or higher than conventional sequential biaxial stretching.
(2) Can handle high-stretching.
(3) In recent years, it has attracted attention because it can freely change the deformation pattern of the film in the stretching, heat treatment and relaxation processes.
[0045]
In the present invention, the stretching temperature when stretching a polyester film is not particularly limited, but when stretching an unstretched film, (the glass transition temperature (Tg) of the polyester film) ° C. to (Tg + 120). ) It is preferable to keep at a temperature of (Tg + 10) ° C to (Tg + 80) ° C. When the stretching temperature is less than Tg ° C., the orientation by stretching proceeds so much that it becomes difficult to stretch to a high magnification.
[0046]
Although the example of the manufacturing method of the biaxially-oriented polyester film of this invention is demonstrated, it is not limited to this. Here, an example is shown in which polyethylene terephthalate is used as the polyester (A) and polyether imide “Ultem” is used as the polyether imide (B), but the production conditions differ depending on the polyester or polyether imide used.
[0047]
First, bis-β-hydroxyethyl terephthalate (BHT) is obtained by esterification from terephthalic acid and ethylene glycol or transesterification of dimethyl terephthalate and ethylene glycol according to a conventional method. Next, while transferring this BHT to the polymerization tank, the polymerization reaction is advanced by heating to 280 ° C. under vacuum. Here, a polyester having an intrinsic viscosity of about 0.5 is obtained. At this time, a predetermined amount of polyetherimide may be added. The obtained polyester is solid-phase polymerized in a pellet form under reduced pressure. In the case of solid phase polymerization, preliminary crystallization is performed at a temperature of 180 ° C. or lower in advance, and then solid phase polymerization is performed at 190 to 250 ° C. under a reduced pressure of about 1 mmHg for 10 to 50 hours. Moreover, as a method for incorporating the particles into the polyester constituting the film, a method in which the particles are dispersed in a predetermined proportion in the form of a slurry in ethylene glycol and this ethylene glycol is polymerized with terephthalic acid is preferable. When adding the particles, for example, if the water sol or alcohol sol obtained at the time of synthesis is added without drying, the dispersibility of the particles is good. It is also effective to mix the aqueous slurry of particles directly with predetermined polyester pellets and knead them into the polyester using a vented twin-screw kneading extruder. As a method of adjusting the content and number of particles, a master of high-concentration particles is prepared by the above method, and this is diluted with polyester that does not substantially contain particles at the time of film formation to adjust the content of particles. The method to do is effective.
[0048]
Next, the polyethylene terephthalate pellets (A) and the polyetherimide pellets (B) are mixed at a constant ratio and supplied to a vent type twin-screw kneading extruder heated to 270 to 300 ° C. , Melt extrusion. The shear rate at this time is 50 to 300 sec.^-1Is preferable, more preferably 100 to 200 sec.^-1The residence time is preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes. Furthermore, when not compatible under the above conditions, the obtained chip may be put into the twin-screw extruder again and extrusion may be repeated until compatible. By the kneading, polyethylene terephthalate and polyetherimide are compatible with each other, and polyester pellets having a single glass transition point can be obtained.
[0049]
The obtained polyetherimide-containing polyester pellets are vacuum dried at 180 ° C. for 3 hours or more, and then supplied to an extruder heated to 280 to 320 ° C. in a nitrogen stream or under vacuum so as not to lower the intrinsic viscosity. And it forms into a film by the method currently performed conventionally. Moreover, it is preferable to use various types of filters, for example, filters made of materials such as sintered metal, porous ceramics, sand, and wire mesh, in order to remove foreign substances and denatured polymers. Moreover, you may provide a gear pump as needed in order to improve fixed_quantity | feed_rate supply property. In the case of a laminated film, using two or more extruders, manifolds or merging blocks, a sheet in which molten polyester or a mixture of polyester and polyetherimide is laminated is extruded from a slit-shaped die, and then on a casting roll. Cool to make an unstretched film.
[0050]
Next, this unstretched film is biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used using a simultaneous biaxial tenter. Here, a simultaneous biaxial stretching method in which stretching is performed simultaneously in the longitudinal direction and the width direction is used. The stretching temperature varies depending on the structural components of polyester (A) and polyetherimide (B) and the constituent components of the laminate. For example, a single layer mixed polymer of polyethylene terephthalate and polyetherimide “Ultem” (registered trademark) The case where consists of is demonstrated and demonstrated. The unstretched film is guided to the linear motor type simultaneous biaxially stretched tenter by gripping both ends of the film with clips, heated to 90 to 150 ° C. in the preheating zone, and simultaneously in both the longitudinal direction and the width direction, Stretch 1 to 10 times in one or two or more stages. In either case, the temperature of the clip that holds the film end is preferably set in the temperature range of 80 to 160 ° C. The stretching temperature in the stretching process is preferably maintained within a temperature range of 90 to 150 ° C., but may be cooled and stretched while suppressing crystallization of the film. In the case of a raw material having a high molecular weight or a material that is difficult to crystallize, the stretching temperature can be preferably increased to 200 ° C. In the latter half of the stretching process, it is preferable to stretch the film while gradually increasing the stretching temperature in two or more stages.
[0051]
Subsequently, in order to impart flatness and dimensional stability to the biaxially stretched polyester film, heat treatment is performed at a temperature range of 150 to 250 ° C, preferably 170 to 230 ° C, more preferably 180 to 220 ° C. Furthermore, in the cooling process from the heat setting temperature, the relaxation treatment is preferably performed in the longitudinal and width directions in the temperature range of 100 to 220 ° C., preferably in the range of 1 to 6% in each direction. The relaxation process may be performed in one stage, may be performed in multiple stages, and a change in temperature distribution may be provided. Thereafter, the film is cooled and wound up to room temperature, if necessary, while being subjected to relaxation treatment in the longitudinal and width directions to obtain a desired biaxially oriented polyester film.
[0052]
[Methods for measuring physical properties and methods for evaluating effects]
The characteristic value measurement method and the effect evaluation method are as follows.
[0053]
(1) Circumferential half-value width X-ray diffractometer (4036A2 type (tube type) manufactured by Rigaku Corporation) under the following conditions using the wide-angle X-ray diffraction method of the crystal plane diffraction peak of the film Measured by a diffractometer method.
X-ray diffractometer 4036A2 type (tube type) manufactured by Rigaku Corporation
X-ray source: CuKα ray (using Ni filter)
Output: 40kV 20mA
Goniometer manufactured by Rigaku Corporation
Slit: 2mmφ-1 ° -1 °
Detector: Scintillation counter
Counting recording device RAD-C type manufactured by Rigaku Corporation
A profile in the circumferential direction is obtained by fixing a sample and a counter that are cut out to 2 cm × 2 cm, aligned in the same direction, and a counter, and rotating the sample in-plane at the diffraction peak position of the crystal plane obtained by 2θ / θ scan. (Β scan). Of the peak profile obtained by β scan, the peak half-value width (deg) was calculated using the valley portions at both ends of the peak as the background.
[0054]
(2) Crystal size obtained from wide-angle X-ray diffraction method
Measurement was carried out by the transmission method under the following conditions using an X-ray diffraction apparatus (4036A2 type, manufactured by Rigaku Corporation).
X-ray diffractometer 4036A2 type, manufactured by Rigaku Corporation
X-ray source: CuKα ray (using Ni filter)
Output: 40kV 20mA
Goniometer manufactured by Rigaku Corporation
Slit: 2mmφ-1 ° -1 °
Detector: Scintillation counter
Counting recording device RAD-C type manufactured by Rigaku Corporation
Samples cut into 2 cm x 2 cm, aligned in the same direction, and solidified with collodion / ethanol solution were set. Of the 2θ / θ intensity data obtained by wide-angle X-ray diffraction measurement, half the surface in each direction From the value range, calculation was performed using the following Scherrer equation. Here, the crystal size was measured in the orientation main axis direction.
Crystal size L (angstrom) = Kλ / β₀cosθ_B
K: Constant (= 1.0)
λ: wavelength of X-ray (= 1.5418 angstrom)
θ_B   : Bragg angle
β₀= (Β_E ²-Β_I ²)^1/2
β_E   : Apparent half width (actual value)
β_I   : Device constant (= 1.046 × 10^-2).
[0055]
(3) Extrapolated glass transition start temperature (Tg-onset), glass transition temperature (Tg)
It measured according to JIS-K7121.

In addition, when a shoulder is observed near the glass transition temperature in the DSC curve, after obtaining the glass transition temperature, the area (unit mJ / mg) of the portion deviated from the baseline is obtained, and the value is 5 mJ / mg or less. If there was, it was set to single Tg.
[0056]
(4) Young's modulus
According to the method prescribed | regulated to ASTM-D882, it measured using the Instron type tensile tester. The measurement was performed under the following conditions.

(5) Thermal contraction rate
It measured according to JIS-C2318.
Sample size: width 10 mm, marked line interval 200 mm
Measurement conditions: temperature 100 ° C, treatment time 30 minutes, no load
The 100 ° C. heat shrinkage rate was determined from the following equation.
[0057]
Thermal contraction rate (%) = [(L₀-L) / L₀] × 100
L₀: Mark interval before heat treatment
L: Mark interval after heat treatment.
[0058]
(6) Intrinsic viscosity
The value calculated from the following equation from the solution viscosity measured at 25 ° C. in orthochlorophenol is used. That is,
ηsp / C = [η] + K [η] 2 · C
Here, ηsp = (solution viscosity / solvent viscosity) −1, C is the weight of dissolved polymer per 100 ml of solvent (g / 100 ml, usually 1.2), and K is the Huggins constant (assuming 0.343). The solution viscosity and solvent viscosity were measured using an Ostwald viscometer.
[0059]
(7) Running durability and storage stability of magnetic tape
A magnetic paint having the following composition is applied on the surface of the biaxially oriented polyester film of the present invention so as to have a coating thickness of 2.0 μm, magnetically oriented, and dried. Next, after forming a backcoat layer having the following composition on the opposite surface, it was calendered and then cured at 70 ° C. for 48 hours. The original tape was slit into a 1/2 inch width, and a 670 m length of magnetic tape was incorporated into the cassette to form a cassette tape.
(Composition of magnetic paint)
・ Ferromagnetic metal powder: 100 parts by weight
-Modified vinyl chloride copolymer: 10 parts by weight
・ Modified polyurethane: 10 parts by weight
・ Polyisocyanate: 5 parts by weight
・ Stearic acid: 1.5 parts by weight
・ Oleic acid: 1 part by weight
・ Carbon black: 1 part by weight
・ Alumina: 10 parts by weight
・ Methyl ethyl ketone: 75 parts by weight
・ Cyclohexanone: 75 parts by weight
・ Toluene: 75 parts by weight
(Backcoat composition)
Carbon black (average particle size 20 nm): 95 parts by weight
Carbon black (average particle size 280 nm): 10 parts by weight
・ Α alumina: 0.1 parts by weight
・ Modified polyurethane: 20 parts by weight
-Modified vinyl chloride copolymer: 30 parts by weight
・ Cyclohexanone: 200 parts by weight
・ Methyl ethyl ketone: 300 parts by weight
・ Toluene: 100 parts by weight
The produced cassette tape was reciprocated 100 times using an IBM Magstar 3590 MODELB1A Tape Drive, and the running durability of the tape was evaluated according to the following criteria. ○ was accepted.
◯: There is no elongation or bending of the tape end face, and no scraped trace is seen.
[0060]
Δ: There is no elongation or bending of the tape end face, but some traces are seen.
[0061]
X: A part of the tape end face is stretched, wakame-like deformation is seen, and a scraped mark is seen.
[0062]
In addition, after reading the above cassette tape into an IBM Magstar 3590 MODELB1A Tape Drive, storing the cassette tape in an atmosphere of 40 ° C. and 80% RH for 100 hours, reproducing the data, Then, the storage stability of the tape was evaluated. ○ was accepted.
○: Played normally without track deviation.
[0063]
Δ: There is no abnormality in the tape width, but some parts cannot be read.
[0064]
X: There is a change in the tape width, and reading is impossible.
[0065]
(8) Tracking resistance of floppy disks
A. Tracking deviation test due to temperature change
The following method is used as the tracking deviation test. Magnetic recording is performed on a floppy disk made of a metal thin film obtained by forming a magnetic recording layer on both surfaces of a base film by sputtering and punching into a disk shape at a temperature of 15 ° C. and a humidity of 60% RH using a ring head. Measure the maximum output and the output envelope of the magnetic sheet. Next, the atmospheric temperature is maintained at 40 ° C. and the humidity is 60% RH, and the maximum output and the output envelope at the temperature are examined. The output envelope at the temperature of 15 ° C. and the humidity of 60% RH, and the temperature of 40 ° C. The output envelope when the humidity is 60% RH is compared to determine the tracking state. The smaller this difference, the better the tracking resistance. When this difference exceeded 3 dB, tracking was evaluated as x, and those within 3 dB were evaluated as ◯.
[0066]
B. Tracking deviation test due to humidity change
A floppy disk made in the same manner as in the previous section was recorded in an atmosphere at a temperature of 25 ° C. and a relative humidity of 20%, and the atmospheric conditions were maintained at a temperature of 25 ° C. and a relative humidity of 70%. Determine the tracking status. As in the previous section, when this difference exceeded 3 dB, the tracking was x, and those within 3 dB were evaluated as ◯.
[0067]
(9) Printability of thermal transfer ribbon
Apply the thermal transfer ink of the following composition to the polyester film for the thermal transfer ribbon of the present invention coated on one side with a hot melt coater on the opposite side of the anti-fusing layer to a coating thickness of 3.5 μm. The thermal transfer ribbon was made.
(Composition of thermal transfer ink)
Carnauba wax: 60.6% by weight
Microcrystalline wax: 18.2% by weight
Vinyl acetate / ethylene copolymer: 0.1% by weight
Carbon black: 21.1% by weight
About the created thermal transfer ribbon, black solid was printed with the barcode printer (BC-8) by Oaks, and printability was evaluated. ○ was accepted.
○: Clearly printed
Δ: Pitch deviation occurs in printing
×: Wrinkles on the ribbon and printing is disturbed
XX: The film is wrinkled during hot melt coating, and the thermal transfer ink cannot be applied uniformly.
[0068]
(10) Capacitor characteristic evaluation
The insulation resistance and dielectric breakdown voltage were evaluated as follows.
[0069]
A. Insulation resistance
Aluminum was vacuum-deposited on one side of the polyester film of the present invention so that the surface resistance value was 2Ω / □. At that time, vapor deposition was performed in a stripe shape having a margin portion running in the longitudinal direction (repetition of the width of the vapor deposition portion of 57 mm and the width of the margin portion of 3 mm). Next, a blade was put in the center of each vapor deposition section and the center of each margin section and slitted to form a tape-shaped take-up reel having a total width of 30 mm with a margin of 1.5 mm width on the left or right. A pair of obtained aluminum vapor deposition films having a symmetric margin was overlapped and wound to a length of 1.5 μF. This wound material is 120 ° C. and 20 kg / cm.²Was pressed and molded at a pressure of 10 minutes. Metallicons were sprayed on both end surfaces to form electrodes, and lead wires were attached to form capacitor samples. Next, 1000 pieces of the 1.5 μF capacitor sample created here were measured as a one-minute value at an applied voltage of 500 V with a super insulation resistance meter 4329A manufactured by YHP in an atmosphere of 23 ° C. and 65% RH. A capacitor sample of less than 5000 MΩ was judged as a defective product according to the following criteria. In the present invention, “◎”, “◯”, and “Δ” were accepted.
A: Less than 10 defective products
○: 10 to 20 defective products
Δ: 20 to less than 50 defective products
X: 50 or more defective products.
[0070]
B. Breakdown voltage
According to the method described in JIS-C-2318, except that a film not subjected to metal vapor deposition is used as a test piece and evaluated as follows.
[0071]
A rubber plate with a rubber shore hardness of about 60 degrees and a thickness of about 2 mm is laid on a metal plate of appropriate size, and 10 pieces of aluminum foil with a thickness of about 6 μm are stacked on it as the lower electrode. The upper electrode is a brass cylinder that weighs about 50 g, has a roundness of about 1 mm in the periphery, and has a smooth bottom surface with a diameter of 8 mm and no scratches. The test piece is previously left in an atmosphere of a temperature of 20 ± 5 ° C. and a relative humidity of 65 ± 5% for 48 hours or more. A test piece is sandwiched between the upper electrode and the lower electrode, and a DC voltage is applied between the electrodes by a DC power source in an atmosphere having a temperature of 20 ± 5 ° C. and a relative humidity of 65 ± 5%, and the DC voltage is set to 100 V per second. The voltage is increased from 0V until the dielectric breakdown occurs. A test is performed on 50 samples, an average value of the dielectric breakdown voltage divided by the thickness of the test piece is obtained, and a value of 400 V / μm or more is regarded as acceptable (◯).
[0072]
【Example】
Based on the following examples, embodiments of the present invention will be described.
[0073]
Example 1
50% by weight of polyethylene terephthalate pellets (inherent viscosity 0.85) obtained by a known method and 50% by weight of polyetherimide pellet “Ultem 1010” (registered trademark of GE Plastics) were heated to 280 ° C. Supplied to a bent type twin-screw kneading extruder, with a shear rate of 100 sec.^-1The polyester chip (I) containing 50% by weight of polyetherimide was obtained by melt extrusion with a residence time of 1 minute. Furthermore, 40% by weight of the chip (I) was made of polyethylene terephthalate (inherent viscosity 0.65, 0.2% by weight of spherical crosslinked polystyrene particles having an average diameter of 0.3 μm as a slip agent, and spherical crosslinked polystyrene particles having an average diameter of 0.8 μm). .01 wt% blended) 60% by weight of pellets and fed to a vented twin-screw kneader / extruder heated to 280 ° C. with a shear rate of 100 sec.^-1The polyester chip (II) containing 20% by weight of polyetherimide was obtained by melt extrusion with a residence time of 1 minute. The resulting chip was transparent and only a single glass transition temperature was observed.
[0074]
Meanwhile, 40% by weight of the polyester chip (I) and 60% by weight of pellets of polyethylene terephthalate (containing 0.16% by weight of spherical silica particles having an intrinsic viscosity of 0.65 and an average diameter of 0.07 μm) are heated to 280 ° C. The polyester chip (III) was obtained by the same method as described above. The resulting chip was transparent and only a single glass transition temperature was observed.
[0075]
To the extruder A heated to 280 ° C. using two extruders, the obtained polyetherimide-containing polyester composition (III) pellets were supplied after being vacuum-dried at 180 ° C. for 3 hours. To the extruder B heated to 1, the pellets of the obtained polyetherimide-containing polyester composition (II) are supplied after vacuum drying at 180 ° C. for 3 hours so that the polyester composition (II) becomes the outermost layer. 3 layers are laminated in a T-die (lamination ratio II / III / II = 1/10/1), solidified by cooling and solidification while applying an electrostatic charge to a cast drum having a surface temperature of 25 ° C. A film was created.
[0076]
The both ends of this unstretched film are held with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 110 ° C., and the area stretching ratio is 12.25 times (longitudinal magnification: 3.5 times). , Transverse magnification: 3.5 times). Subsequently, the film temperature was set to 150 ° C., and the film was redrawn simultaneously biaxially at an area draw ratio of 1.96 times (longitudinal ratio: 1.4 times, lateral ratio: 1.4 times), and the temperature was 210 under a constant length. After heat treatment at 10 ° C. for 10 seconds, 2% relaxation treatment is performed in each of the longitudinal and transverse directions to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0077]
The composition, characteristics, etc. of this biaxially oriented polyester film are as shown in Table 1 and Table 2, and have excellent characteristics as films for various uses such as for magnetic recording media.
[0078]
Examples 2-4
In the same manner as in Example 1, after changing the content of polyetherimide as shown in Table 1 to obtain a polyetherimide-containing polyester composition, a biaxially oriented polyester film was prepared in the same manner as in Example 1. obtain.
[0079]
As shown in Table 2, the properties of this biaxially oriented polyester film are excellent as films for various uses such as for magnetic recording media.
[0080]
Example 5
After obtaining an unstretched polyester film by the same method as in Example 1, both ends of the unstretched film are held with clips and guided to a linear motor type simultaneous biaxial stretching tenter, and the film temperature is heated to 110 ° C. The film is simultaneously biaxially stretched at an area stretch ratio of 12.25 times (longitudinal magnification: 3.5 times, lateral magnification: 3.5 times). Subsequently, the film temperature was set to 150 ° C., and the film was stretched 1.4 times in the longitudinal direction. Subsequently, the film was biaxially re-stretched sequentially 1.4 times in the width direction, and the temperature was 210 ° C. under a constant length. After heat treatment for 10 seconds, 2% relaxation treatment is performed in each of the vertical and horizontal directions to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0081]
The composition, characteristics, etc. of this biaxially oriented polyester film are as shown in Table 1 and Table 2, and have excellent characteristics as films for various uses such as for magnetic recording media.
[0082]
Example 6
Polyethylene-2,6-naphthalate (PEN) obtained by a known method (inherent viscosity of 0.65, glass transition temperature of 125 ° C., 0.2% by weight of spherical crosslinked polystyrene particles having an average diameter of 0.3 μm and an average diameter of 0.1%). 80% by weight of pellets of 8 μm spherical crosslinked polystyrene particles (containing 0.01% by weight) and 20% by weight of polyetherimide pellets “Ultem 1010” (registered trademark of GE Plastics) heated to 290 ° C. Is supplied to a twin-screw kneading extruder with a shear rate of 100 sec.^-1The polyester chip (IV) containing 20% by weight of polyetherimide was obtained by melt extrusion with a residence time of 1 minute. The resulting chip was transparent and only a single glass transition temperature was observed.
[0083]
On the other hand, 80% by weight of a pellet of polyethylene-2,6-naphthalate (PEN) (containing an intrinsic viscosity of 0.65, a glass transition temperature of 125 ° C., and 0.16% by weight of spherical silica particles having an average diameter of 0.07 μm) and polyether 20% by weight of imide pellets “Ultem 1010” (registered trademark of GE Plastics Co., Ltd.) was supplied to a vented twin-screw kneading extruder heated to 290 ° C., and 20 wt. % Polyester chip (V) was obtained. The resulting chip was transparent and only a single glass transition temperature was observed.
[0084]
To the extruder A heated to 290 ° C. using two extruders, the obtained polyetherimide-containing polyester composition (V) pellets were supplied after vacuum drying at 180 ° C. for 3 hours. The obtained polyetherimide-containing polyester composition (IV) pellets were dried in vacuum at 180 ° C. for 3 hours and then fed to the extruder B heated to a temperature so that the polyester composition (IV) became the outermost layer. In order to stack three layers, they are merged in a T-die (lamination ratio IV / V / IV = 1/10/1) and solidified by cooling and solidification while applying an electrostatic charge to a cast drum having a surface temperature of 25 ° C. A film was created.
[0085]
The both ends of this unstretched film are held with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 145 ° C., and the area stretching ratio is 25.0 times (longitudinal ratio: 5.0 times). , Transverse magnification: 5.0 times). Subsequently, after heat treatment at a temperature of 210 ° C. for 10 seconds under a constant length, a relaxation treatment of 2% in each of the longitudinal and transverse directions is performed to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0086]
The composition, characteristics, etc. of this biaxially oriented polyester film are as shown in Table 1 and Table 2, and have excellent characteristics as films for various uses such as for magnetic recording media.
[0087]
Example 7
After obtaining a polyetherimide-containing polyester composition (III) in the same manner as in Example 1, the polyetherimide-containing polyester composition was used in the extruder A heated to 280 ° C. using two extruders. The pellet of (III) was vacuum dried at 180 ° C. for 3 hours and then supplied to the extruder B, which was also heated to 280 ° C., and was supplied with polyethylene terephthalate (PET) (VI) (inherent viscosity 0.65, glass transition temperature 75 After vacuum drying pellets of 0.2% by weight of spherical crosslinked polystyrene particles having an average diameter of 0.3 μm and 0.01% by weight of spherical crosslinked polystyrene particles having an average diameter of 0.8 μm as a slipping agent at 180 ° C. for 3 hours. Supplied, and merged in a T-die to laminate three layers so that polyethylene terephthalate (VI) becomes the outermost layer (lamination ratio VI / III / VI = 1/10/1), surface temperature 25 ° C. Closely it cooled and solidified while applying an electrostatic charge to cast drum to prepare a laminated unstretched film.
[0088]
Both ends of this unstretched film are gripped with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 105 ° C., and the area stretching ratio is 12.25 times (longitudinal ratio: 3.5 times). , Transverse magnification: 3.5 times). Subsequently, the film temperature was set to 150 ° C., and the film was redrawn simultaneously biaxially at an area draw ratio of 1.96 times (longitudinal ratio: 1.4 times, lateral ratio: 1.4 times), and the temperature was 210 under a constant length. After heat treatment at 10 ° C. for 10 seconds, 2% relaxation treatment is performed in each of the longitudinal and transverse directions to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0089]
The composition, characteristics, etc. of this biaxially oriented polyester film are as shown in Table 1 and Table 2, and have excellent characteristics as films for various uses such as for magnetic recording media.
[0090]
Example 8
After obtaining a polyetherimide-containing polyester composition (II) in the same manner as in Example 1, the polyetherimide-containing polyester composition was added to the extruder A heated to 280 ° C. using two extruders. The pellets of (II) were vacuum-dried at 180 ° C. for 3 hours and then supplied to the extruder B, which was also heated to 280 ° C., to polyethylene terephthalate (PET) (VII) (intrinsic viscosity 0.65, glass transition temperature 75 So that the polyetherimide-containing polyester composition (II) becomes the outermost layer after vacuum drying at 180 ° C. for 3 hours. Combined in a T-die to laminate 3 layers (lamination ratio II / VII / II = 1/10/1), solidified by cooling and solidification while applying an electrostatic charge to a cast drum with a surface temperature of 25 ° C. And create a thin film.
[0091]
The both ends of this unstretched film are gripped with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 95 ° C., and the area stretching ratio is 12.25 times (longitudinal ratio: 3.5 times). , Transverse magnification: 3.5 times). Subsequently, the film temperature was set to 150 ° C., and the film was redrawn simultaneously biaxially at an area draw ratio of 1.96 times (longitudinal ratio: 1.4 times, lateral ratio: 1.4 times), and the temperature was 210 under a constant length. After heat treatment at 10 ° C. for 10 seconds, 2% relaxation treatment is performed in each of the longitudinal and transverse directions to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0092]
The composition, characteristics, etc. of this biaxially oriented polyester film are as shown in Table 1 and Table 2, and have excellent characteristics as films for various uses such as for magnetic recording media.
[0093]
Comparative Example 1
In the three-layer lamination (II / III / II), an unstretched film is prepared in the same manner as in Example 1 except that all the three layers are made of polyethylene terephthalate (PET) in which polyetherimide is not mixed.
[0094]
The both ends of this unstretched film are gripped by clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 90 ° C., and the area stretching ratio is 12.25 times (longitudinal ratio: 3.5 times). , Transverse magnification: 3.5 times). Subsequently, the film temperature was set to 150 ° C., and the film was redrawn simultaneously biaxially at an area draw ratio of 1.96 times (longitudinal ratio: 1.4 times, lateral ratio: 1.4 times), and the temperature was 210 under a constant length. After heat treatment at 10 ° C. for 10 seconds, 2% relaxation treatment is performed in each of the longitudinal and transverse directions to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0095]
This biaxially oriented polyester film does not contain polyimide ether, and its composition and characteristics are inferior as films for various uses such as magnetic recording media as shown in Tables 1 and 2. It was.
[0096]
Comparative Example 2
The both ends of the unstretched polyester film obtained in the same manner as in Example 1 were gripped with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature was heated to 110 ° C., and the longitudinal direction was 3.1. The film is stretched twice and then successively biaxially stretched 3.5 times in the width direction. Subsequently, the film temperature is set to 150 ° C., the film is stretched 1.4 times in the longitudinal direction, and further stretched 1.4 times in the width direction. After heat treatment for 10 seconds at a temperature of 210 ° C. under a constant length, a relaxation treatment of 2% in each of the longitudinal and transverse directions is performed to obtain a biaxially stretched polyester film having a thickness of 5 μm.
[0097]
As shown in Table 1, this polyester film has a half width by crystal orientation analysis outside the scope of the present invention, and its characteristics are inferior as films for various uses such as for magnetic recording media as shown in Table 2. It was a thing.
[0098]
Comparative Example 3
The unstretched polyester film obtained in the same manner as in Example 1 was stretched 3.2 times at a temperature of 110 ° C. in a single stage in the longitudinal direction using a roll-type stretching machine, and further in the width direction using a tenter. The film was stretched 3.8 times at 100 ° C. Subsequently, the film was re-stretched 1.5 times at a temperature of 135 ° C. in two stages with a roll-type stretching machine, and re-stretched 1.4 times at a temperature of 200 ° C. in the width direction using a tenter. After heat treatment at a temperature of 210 ° C. for 10 seconds under a constant length, a relaxation treatment of 2% in the width direction was performed to obtain a biaxially oriented polyester film having a thickness of 5 μm.
[0099]
As shown in Table 1, this polyester film has a half width by crystal orientation analysis outside the scope of the present invention, and its characteristics are inferior as films for various uses such as for magnetic recording media as shown in Table 2. It was a thing.
[0100]
Example 9
40% by weight of a 50% by weight polyetherimide-containing polyester chip (I) obtained in the same manner as in Example 1 and polyethylene terephthalate (6% by weight of spherical crosslinked polystyrene particles having an intrinsic viscosity of 0.65 and an average diameter of 0.3 μm) Blended with 60% by weight of the pellets and fed to a vented twin-screw kneading extruder heated to 280 ° C., with a shear rate of 100 sec.^-1The polyester chip (VIII) containing 20% by weight of polyetherimide was obtained by melt extrusion at a residence time of 1 minute. The resulting chip was transparent and only a single glass transition temperature was observed.
[0101]
On the other hand, 50% by weight of polyetherimide-containing polyester chip (I) obtained in the same manner as in Example 1 was mixed with 40% by weight of polyethylene terephthalate (inherent viscosity 0.65, no particles) pellets 60% by weight. Supplied to a vent type twin-screw kneader / extruder heated to 280 ° C., shear rate of 100 sec^-1The polyester chip (IX) containing 20% by weight of polyetherimide was obtained by melt extrusion with a residence time of 1 minute. The resulting chip was transparent and only a single glass transition temperature was observed.
[0102]
Polyesterimide-containing polyester chips (VIII) pellets were vacuum dried at 180 ° C. for 3 hours and supplied to Extruder A heated to 280 ° C. using two extruders, and also heated to 280 ° C. Polyesterimide-containing polyester chips (IX) pellets were fed to extruder B after being vacuum-dried at 180 ° C. for 3 hours, joined in a T-die (lamination ratio VIII / IX = 1/250), surface temperature An unstretched film is produced by electrostatically adhering to a cast drum at 25 ° C. and solidifying by cooling. Both ends of the obtained unstretched film are held with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 110 ° C., and the area stretching ratio is 12.25 times (longitudinal ratio: 3. (5 times, transverse magnification: 3.5 times) at the same time biaxially stretched, heat treated for 10 seconds at a temperature of 210 ° C. under constant length, and then subjected to a relaxation treatment of 2% in each direction, biaxially stretching 75 μm thick A polyester film is obtained. The obtained biaxially oriented polyester film is processed for a magnetic recording medium to evaluate the practical characteristics as a floppy disk. The results have excellent characteristics as shown in Table 3.
[0103]
Comparative Example 4
In Extruder A heated to 280 ° C. using two extruders, polyethylene terephthalate (containing 6% by weight of spherical cross-linked polystyrene particles having an intrinsic viscosity of 0.65 and an average diameter of 0.3 μm) was added at 180 ° C. 3 To the extruder B, which was supplied after being vacuum-dried for a time and also heated to 280 ° C., pellets of polyethylene terephthalate (inherent viscosity 0.65, no particles) were supplied after vacuum drying at 180 ° C. for 3 hours, They are joined together (lamination ratio A / B = 1/250), electrostatically adhered to a cast drum having a surface temperature of 25 ° C., cooled and solidified to produce an unstretched film.
[0104]
Both ends of the obtained unstretched film are gripped with clips and guided to a linear motor type simultaneous biaxial stretching tenter, the film temperature is heated to 95 ° C., and the area stretching ratio is 12.25 times (longitudinal ratio: 3. (5 times, transverse magnification: 3.5 times) at the same time biaxially stretched, heat treated for 10 seconds at a temperature of 210 ° C. under constant length, and then subjected to a relaxation treatment of 2% in each direction, biaxially stretching 75 μm thick A polyester film is obtained.
[0105]
The obtained biaxially oriented polyester film is processed for a magnetic recording medium to evaluate the practical characteristics as a floppy disk. The results are inferior to practical properties as shown in Table 3.
[0106]
Example 10
40% by weight of a 50% by weight polyetherimide-containing polyester chip (I) obtained in the same manner as in Example 1, polyethylene terephthalate (0.2% by weight of silicon dioxide particles having an intrinsic viscosity of 0.65 and an average diameter of 1.0 μm) % Blended) 60% by weight of the pellets and fed to a vented twin-screw kneading extruder heated to 280 ° C. with a shear rate of 100 sec.^-1The polyester chip (X) containing 20% by weight of polyetherimide was obtained by melt extrusion with a residence time of 1 minute. The resulting chip was transparent and only a single glass transition temperature was observed.
[0107]
The polyester chip (X) is vacuum-dried at 180 ° C. for 3 hours, then supplied to an extruder heated to 280 ° C., melt-extruded, and discharged into a sheet form from a T-die. Further, this sheet is brought into close contact with a cooling drum having a surface temperature of 25 ° C. by electrostatic force to be cooled and solidified to obtain an unstretched film. A coating agent having the following composition is applied to one side of the unstretched film with a gravure coater so that the coating thickness after drying is 0.5 μm.
(Coating composition)
Acrylic acid ester: 14.0% by weight
Amino-modified silicone: 5.9% by weight
Isocyanate: 0.1% by weight
Water: 80.0% by weight
Thereafter, both ends of the obtained unstretched film are gripped with clips, guided to a linear motor type simultaneous biaxial stretching tenter, and manufactured under the same stretching conditions as in Example 1. The obtained film having a thickness of 4 μm is subjected to processing for a thermal transfer ribbon to evaluate practical characteristics for the thermal transfer ribbon. The results are excellent as shown in Table 4.
[0108]
Comparative Example 5
In Example 10, a polyethylene terephthalate containing no polyetherimide is used and stretched in the same manner as in Comparative Example 1 to obtain a biaxially oriented polyester film. The obtained film having a thickness of 4 μm is subjected to processing for a thermal transfer ribbon to evaluate practical characteristics for the thermal transfer ribbon. The results are inferior to practical properties as shown in Table 4.
[0109]
Example 11
40% by weight of a 50% by weight polyetherimide-containing polyester chip (I) obtained in the same manner as in Example 1 and 0.1% by weight of aggregated silica particles having an intrinsic viscosity of 0.65 and an average diameter of 1.2 μm % Blended) 60% by weight of the pellets and fed to a vented twin-screw kneading extruder heated to 280 ° C. with a shear rate of 100 sec.^-1The polyester chip (XI) containing 20% by weight of polyetherimide was obtained by melt extrusion with a residence time of 1 minute. The resulting chip was transparent and only a single glass transition temperature was observed.
[0110]
The polyester chip (XI) is vacuum-dried at 180 ° C. for 3 hours, then supplied to an extruder heated to 280 ° C., melt-extruded, and discharged into a sheet form from a T-die. Further, this sheet is brought into close contact with a cooling drum having a surface temperature of 25 ° C. by electrostatic force to be cooled and solidified to obtain an unstretched film. Both ends of this unstretched film are gripped with clips and guided to a linear motor type simultaneous biaxial stretching tenter, and a 4 μm thick film produced under the same stretching conditions as in Example 1 is processed for a capacitor. To evaluate practical characteristics. The results are excellent as shown in Table 5.
[0111]
Comparative Example 6
In Example 11, using the polyethylene terephthalate which does not contain polyetherimide, it extends similarly to the comparative example 1, and obtains a biaxially-oriented polyester film. The obtained film having a thickness of 4 μm is processed for a capacitor to evaluate practical characteristics. The results are inferior to practical characteristics as shown in Table 5.
[0112]
[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

【The invention's effect】
According to the present invention, a biaxially oriented polyester film with improved mechanical properties such as Young's modulus and dimensional stability of the film can be obtained. It can be widely used for various film applications such as magnetic recording media, condensers, thermal transfer ribbons, and thermal stencil printing base paper. Specifically, it is possible to obtain a base film excellent in running durability, storage stability, floppy tracking resistance and the like for a magnetic recording medium and excellent in printability for a thermal transfer ribbon.

Claims (6)

A biaxially oriented polyester film comprising a polyester (A) and a polyetherimide (B) and having a single glass transition temperature, wherein the film is analyzed by crystal orientation analysis by a diffractometer method of wide angle X-ray diffraction Simultaneous biaxial stretching , characterized in that the half-value width in the circumferential direction of the diffraction peak of the crystal plane in the biaxially oriented polyester main chain direction obtained when rotated about the normal is in the range of 55 to 85 degrees biaxially oriented polyester film that is. The biaxially oriented polyester film that has been simultaneously biaxially stretched according to claim 1, wherein the polyetherimide (B) is contained in an amount of 1 to 50% by weight. The biaxially oriented polyester film stretched simultaneously biaxially according to claim 1 or 2, wherein the sum of Young's modulus in the longitudinal direction and the width direction is 10 to 25 (GPa). The biaxially oriented polyester film stretched simultaneously biaxially according to any one of claims 1 to 3, wherein the heat shrinkage rate at 100 ° C for 30 minutes in the longitudinal direction and the width direction is 0.01 to 2.0%. . The biaxially oriented polyester film stretched simultaneously biaxially according to any one of claims 1 to 4, wherein the polyester (A) has an ethylene terephthalate unit as a main component. The biaxially oriented polyester film stretched simultaneously biaxially according to claim 5, wherein the extrapolated glass transition start temperature (Tg-onset) is 90 to 150 ° C.