JP2005053980A - Thermoplastic resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film having the following characteristics: projections at the running surface side are hardly transferred to the magnetic surface side; since the air flow between the film and a guide roll is smooth, the film has a high-speed running stability; and the film has a high quality as the base film for magnetic tape for a magnetic recording device. <P>SOLUTION: The thermoplastic resin film is a biaxially oriented film containing at least 50 wt% polyester. In at least one surface layer part, inert particles are aligned or domains consisting of a thermoplastic resin other than polyester are aligned, in one direction in the plane. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３５】
ただし、式中のＲ^１は、
【００３６】
【化３】

【００３７】
【化４】

【００３８】
などの脂肪族炭化水素基、脂環族炭化水素基、芳香族炭化水素基から選ばれた一種もしくは二種以上の基を表し、
また、式中のＲ^２は、
【００３９】
【化５】

【００４０】
などの脂肪族炭化水素基、脂環族炭化水素基、芳香族炭化水素基から選ばれた一種もしくは二種以上の基を表す。
【００４１】
かかるポリイミドは、テトラカルボン酸および／またはその酸無水物と、脂肪族一級モノアミン、芳香族一級モノアミン、脂肪族一級ジアミンおよび芳香族一級ジアミンよりなる群から選ばれる一種もしくは二種以上の化合物を脱水縮合することにより得ることができる。
【００４２】
ポリエステルとの溶融成形性や取り扱い性、表面突起の形成性などの点から、下記一般式で示されるような、ポリイミド構成成分にエーテル結合を含有するポリエーテルイミドが特に好ましい。
【００４３】
【化６】

【００４４】
（ただし、上記式中Ｒ^３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、Ｒ^４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、および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。）
上記Ｒ^３、Ｒ^４としては、例えば、下記式群に示される芳香族残基
【００４５】
【化７】

【００４６】
を挙げることができる。（式中のｎは１〜５の整数）
本発明では、ポリエステルとの親和性、コスト、溶融成形性等の観点から、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である、下記式で示される繰り返し単位を有するポリマーが好ましく、ポリエステルとの相分離ドメインの形成し易さの観点から、ｐ−フェニレンジアミンとの縮合物が特に好ましい。また、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との縮合物とｐ−フェニレンジアミンとの縮合物を共に用いた場合、混合比によってポリエステル中における分散径を制御することができ好ましい。
【００４７】
【化８】

【００４８】
または
【００４９】
【化９】

【００５０】
（ｎは２以上の整数、好ましくは２０〜５０の整数）
このポリエーテルイミドは、“ウルテム”（登録商標）の商品名で、ジーイープラスチックス社より入手可能である。
【００５１】
ポリエステル以外の熱可塑性樹脂として用いられる上記ポリエーテルスルホンは、１つのスルホニル基と１つまたは２つのエーテル基とで芳香族環が結合された下記式の繰り返し単位を有するポリマーであるが、他の構造単位がある程度共重合されていてもよい。
【００５２】
【化１０】

【００５３】
【化１１】

【００５４】
【化１２】

【００５５】
ポリエステル以外の熱可塑性樹脂として用いられる上記ポリスルホンは、下記式の繰り返し単位を有するポリマーであるが、例えばアルキル基などの官能基を含んでいてもよく、また他の構造単位がある程度共重合されていてもよい。
【００５６】
【化１３】

【００５７】
本発明の熱可塑性樹脂フィルムを構成するポリマーには、ドメイン径（分散径）を制御するために、必要に応じて、相溶化剤を併用してもよい。この場合、相溶化剤の種類は、ポリマーの種類によって異なるが、添加量は０．０１〜１０重量％が好ましい。
【００５８】
本発明の熱可塑性樹脂フィルムがポリエステル以外の熱可塑性樹脂を含む場合、本発明のフィルム層中の１種類のポリエステル以外の熱可塑性樹脂の含有量は、フィルム中のポリマーアロイに対する量で１〜３０重量％の範囲にあることが好ましい。さらに好ましくは、５〜１５重量％である。一般的にポリエステルと本発明の熱可塑性樹脂の溶融粘度は大きく異なるため、熱可塑性樹脂の含有量が１重量％未満であると、押出機にて十分に微分散させることが困難な場合があり、熱可塑性樹脂のドメインが粗大分散物となり、また、ドメインが整列しにくい場合がある。１種類の熱可塑性樹脂の含有量が３０重量％を超える量であると、相分離構造が海島構造とならずに、相互連続構造となってしまい、ドメインの整列が起こらない場合がある。
【００５９】
熱可塑性樹脂を２種類以上含む場合、本発明のフィルム層中のポリエステル以外の熱可塑性樹脂の総含有量は、１〜５０重量％の範囲にあることが好ましい。熱可塑性樹脂の含有量が１重量％未満であると、押出機にて十分に微分散させることが困難な場合があり、熱可塑性樹脂の含有量が５０重量％を超える量であると、延伸性が不良となって、製造が困難となる場合がある。
【００６０】
本発明において、ポリエステル以外の熱可塑性樹脂をポリエステルに添加する時期は、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、重合後に添加してもよい。また、溶融押出前に、混合してペレタイズしてもよい。
【００６１】
ペレタイズの際に、一旦、ポリエステルとポリエステル以外の熱可塑性樹脂を同程度の含有量比（例えば、ポリエステル以外の熱可塑性樹脂の含有量が４０〜６０重量％）からなるマスターペレットを作成してから、さらにポリエステルで希釈して、所定の濃度に調整する方法を用いると、ポリマー同士の分散性が向上し、分散不良物の発生を抑制し、本発明のポリマーとしてより好ましい分散状態を示すものとなる。
【００６２】
また本発明のポリマーをより好ましい分散状態に調整する他の方法としては、例えば、タンデム押出機を用いて混合する方法、粉砕器で熱可塑性樹脂を粉末状に粉砕した後に混合する方法、両者を溶媒に溶解し共沈させることにより混合する方法、一方を溶媒に溶かした溶液状とした後に他方に混合する方法なども挙げられるが、さらには、異なる２種類の熱可塑性樹脂を二軸押出機を用いて溶融混合、または溶媒に溶かした溶液として混合した後に溶媒を揮発させるなどして、熱可塑性樹脂／熱可塑性樹脂のブレンド物を作成した後にポリエステルと溶融混合する方法なども好ましく挙げられるが、この限りではない。
【００６３】
本発明の熱可塑性樹脂フィルムは、ポリマーの溶融粘度、押出の際の剪断力、不活性粒子の粒径や、ポリマードメイン径、不活性粒子の粒子濃度やポリエステル中の熱可塑性樹脂濃度が関係する流体力学的効果によるものと考えられるが、フィルム（積層フィルムの場合、本発明のフィルム層）の面方向における少なくとも１方向に整列構造を有するドメインまたは不活性粒子が存在している（以後、ドメインをポリマードメインということがある）。不活性粒子またはポリマードメインが方向性をもって整列することによって、フィルムの最表面として用いる場合には、ライン状に突起が整列した異方性の表面を得ることができ、これによって、例えば磁気テープの走行面として用いた場合には、高速で走行させた場合のガイドロールとのエア噛みを低減し、高速走行時のテープの横ずれを低減させたり、ライン状の突起によって、厚み方向にかかる力を分散することによって、テープ保存時の厚み方向のテープパックストレスによる走行面側の突起の磁性面側への転写を抑制することができる。また、フィルム中央層に用いた場合は、ドメイン、不活性粒子いずれの場合でも、表面層の形態に影響を与えることなく、整列方向に裂けやすい性質を付与することができる。
【００６４】
なお、本発明でいう「不活性粒子またはドメインが、面方向における少なくとも１方向に整列構造を有している」とは下記の方法で決定する。透過型電子顕微鏡（ＴＥＭ）でフィルムの表層（３０μｍ□、厚み約０．５μｍ）を３０点観察する。フィルムの面内のある１方向を長辺とする３０μｍ×１μｍの長方形中に観察される粒子または熱可塑性樹脂のドメイン個数（Ｎ_１）と、上記方向とフィルム面内で垂直な方向を長辺とする３０μｍ×１μｍの長方形中に観察される粒子または熱可塑性樹脂のドメイン個数（Ｎ_２）が以下の関係にある部分が３０点中１５点以上観察されることをいう。なお、観察する長方形部分（３０μｍ×１μｍ）の中心点はＴＥＭ観察部分（３０μｍ□）の中心点とする。
【００６５】
Ｎ_１＞Ｎ_２の場合、Ｎ_１／Ｎ_２＞１．３
Ｎ_２＞Ｎ_１の場合、Ｎ_２／Ｎ_１＞１．３
本発明の熱可塑性樹脂フィルムを磁気記録媒体用途として用いる場合、少なくとも一方の表面の表面粗さＲａは、１ｎｍ〜２５ｎｍが好ましく、より好ましくは５〜１５ｎｍ、特に好ましくは７〜１２ｎｍである。Ｒａが１ｎｍより小さい場合は、フィルム製造、加工工程などで、搬送ロールなどとの摩擦係数が大きくなり、工程トラブルを起こすことがある。また、Ｒａが２５ｎｍより大きい場合は、高密度記録の磁気テープとして用いる場合に、磁性面側への転写が生じる場合がある。
【００６６】
上記表面は、特に限定されないが、不活性粒子またはポリエステル以外の熱可塑性樹脂からなるドメインが整列している側の表面（以下、Ｓ面という）であることが好ましい。
【００６７】
また、本発明の熱可塑性樹脂フィルムを磁気記録媒体以外の用途に用いる場合はこの限りではなく、例えば包装用途として用いる場合には、Ｒａは、製造、加工工程の滑り性の観点から２０ｎｍ〜１００ｎｍが好ましい。
【００６８】
また、特に限定されないが、本発明の熱可塑性樹脂フィルムのＳ面と反対側の表面（以下、Ｂ面という）の中心線表面粗さＲａは、使用用途によって、適切な範囲は異なる。例えば、磁気記録媒体用途で磁気記録面側として用いる場合、１ｎｍ〜１０ｎｍが好ましく、さらに好ましくは２〜８ｎｍである。また、例えば、磁気記録媒体用途で走行面側として用いる場合、５ｎｍ〜１５ｎｍが好ましく、さらに好ましくは９〜１２ｎｍである。また、例えば包装用途として用いる場合には、Ｒａは、製造、加工工程の滑り性の観点から２０ｎｍ〜１００ｎｍが好ましい。
【００６９】
本発明の熱可塑性樹脂フィルムを含むフィルムの総厚みは、使用用途によって、適切な範囲は異なり、特に限定されないが、１〜５００μｍが好ましく、薄膜用途や作業性などの観点から、より好ましくは３〜３００μｍの範囲である。中でも、例えば、磁気テープ用途に用いる場合には、総厚みが３〜１５μｍが好ましく、より好ましくは４〜８μｍである。
【００７０】
本発明の熱可塑性樹脂フィルムは、用途に応じて、単層フィルムで用いてもよいし、積層フィルム中の少なくとも１層のフィルム層として用いても良い。積層フィルムとして用いる場合の積層形態としては、例えば、基層部／積層部の２層積層構成、積層部／基層部／積層部や、積層部／積層部／基層部の３層積層構成、積層部／積層部／基層部／積層部の４層構成などが挙げられる。なお、ここでいう基層部とは、一般的にフィルム中で最も厚みの厚い層であり、例えば、磁気記録媒体用途などでは、主に強度、寸法安定性の保持などの機能を分担する層である。また、ここでいう積層部とは、基層部よりもフィルム層の厚みが薄い層であり、例えば、比較的粗い表面とすることで、フィルムの搬送性や、巻き特性を良化させることができ、磁気テープ用途などでは、良好な走行性を得るためなどに機能する層である。
【００７１】
本発明の熱可塑性樹脂フィルムを積層フィルムとして用いる場合、本発明のフィルム層をフィルム中のどの層に用いるかは、用途、目的によって異なる。例えば、磁気テープなどの磁気記録媒体用途で、ガイドピンとの摩擦を低減する目的に用いる場合は、基層部／積層部の２層積層フィルムの積層部に用いることができる。また、平滑でかつ磁気ヘッドとの滑り性を有する表面設計に用いる場合には基層部に用いても良い。また、包装材料用途などに用いて、易カット性を付与する場合には、積層部／基層部／積層部の３層積層フィルムの基層部に用いることができる。
【００７２】
本発明の熱可塑性樹脂フィルムを積層フィルムとして用いる場合、積層部の厚みは用途によって異なるが、例えば、磁気記録媒体用途では、フィルム強度や表面平滑性の観点から、０．０５μｍ〜２μｍが好ましく、包装材料用途では、製造上の容易さから、１μｍ〜５μｍが好ましい。
【００７３】
本発明の熱可塑性樹脂フィルムを積層フィルムとして用いる場合、本発明のフィルム以外のフィルム層を構成する樹脂成分は、ポリエステルのみでもよいし、ポリエステルと本発明のポリエステル以外の熱可塑性樹脂からなるポリマーアロイでも良い。特に、ポリエチレンテレフタレートまたはポリ（エチレン−２，６−ナフタレンジカルボキシレート）を主たる樹脂成分とする場合、製膜性が良好で、高いフィルム強度が得られる好ましい。
【００７４】
本発明の熱可塑性樹脂フィルムを積層フィルムとして用いる場合、本発明のフィルム以外のフィルム層には、フィルムの搬送性向上などの目的で不活性粒子を含有しても良い。その場合の粒子は、特に限定されず、平均粒径１ｎｍ〜５μｍ程度の無機または有機の粒子で、本発明のポリマー中で化学反応を起こしたり、電磁気的影響により磁気記録に悪影響を与えないものである。粒子の種類としては、酸化チタン、炭酸カルシウム、カオリン、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、シリコーン、イミド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粒子（いわゆる内部粒子）や、界面活性剤などがある。粒子の平均粒径や含有量はフィルム用途や積層構成によって大きく異なる。特に、磁気テープなどの磁気記録媒体用途に用いる場合、通常は、一つのフィルム層には粒径の小さな粒子を添加し、反対側のフィルム層には比較的粒径の大きな粒子を添加する手法が一般的である。
【００７５】
本発明の熱可塑性樹脂フィルムは、本発明の効果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。
【００７６】
本発明の熱可塑性樹脂フィルムのヤング率は、フィルムの使用用途によって大きく異なるが、例えば、磁気記録媒体用途として用いる場合、長手方向のヤング率と幅方向のヤング率の和は、磁気テープの伸び変形などの観点から、９〜２５ＧＰａの範囲であることが好ましく、より好ましくは１１〜２２ＧＰａ、さらに好ましくは１４〜２０ＧＰａである。また、長手方向のヤング率は、磁気ヘッドとのヘッド当たりなどの観点から、４．５ＧＰａ以上が好ましく、より好ましくは５．５ＧＰａ以上、最も好ましくは、６．５ＧＰａ以上である。幅方向のヤング率は、テープエッジダメージなどの観点から、４．５ＧＰａ以上が好ましく、より好ましくは５ＧＰａ以上、最も好ましくは、５．５ＧＰａ以上である。
【００７７】
本発明の熱可塑性樹脂フィルムのポリマーのガラス転移開始温度（Ｔｇ）は、特に限定されないが、フィルムの耐熱性や成形加工性などの観点から、８０〜１５０℃であることが好ましく、より好ましくは９０〜１３０℃、さらに好ましくは１００〜１２０℃の範囲内である。
【００７８】
本発明の熱可塑性樹脂フィルムのポリエステルがＰＥＴである場合、本発明の熱可塑性樹脂フィルムの２８０℃、１，０００秒^−１における溶融粘度は３００〜１，０００Ｐａ・ｓが好ましく、さらに好ましくは４００〜８００Ｐａ・ｓである。上記範囲の溶融粘度であれば、Ｔダイ押出の際の剪断応力によって、不活性粒子やポリマードメインが１方向に整列し易いため好ましい。
【００７９】
また、本発明の熱可塑性樹脂フィルムのポリエステルがＰＥＮである場合、本発明の熱可塑性樹脂フィルムの３２０℃、１，０００秒^−１における溶融粘度は４００〜１，５００Ｐａ・ｓが好ましく、さらに好ましくは６００〜１，０００Ｐａ・ｓである。上記範囲の溶融粘度であれば、Ｔダイ押出の際の剪断応力によって、不活性粒子やポリマードメインが１方向に整列し易いため好ましい。
【００８０】
本発明の熱可塑性樹脂フィルムの用途は、特に限定されないが、磁気記録媒体用ベースフィルムやコンデンサー用途、感熱転写リボン用途、感熱孔版用途、包装用途、光学材料用途などに用いられる。中でも、磁気テープ用ベースフィルムの走行面として用いれば、ガイドピンとの空気の流動特性が良化し、走行性が向上したり、平滑な磁性面側への転写を抑制することができる。また、包装用途としては、引き裂き性の異方性を利用し、易カット性を付与することができる。
【００８１】
本発明の熱可塑性樹脂フィルムは、さらに他のポリマー層、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。
【００８２】
本発明の熱可塑性樹脂フィルムは、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。
【００８３】
また、本発明の熱可塑性樹脂フィルムの少なくとも片面に磁性層を設けることにより、磁気記録媒体として用いることができる。この場合、磁性層としては、強磁性金属薄膜や強磁性金属微粉末を結合剤中に分散してなる磁性層や金属酸化物塗布による磁性層などが好適な例として挙げられる。前記強磁性金属薄膜に用いる金属としては、鉄、コバルト、ニッケルやその合金等が好ましい。また、前記強磁性金属微粉末を結合剤中に分散してなる磁性層に用いる強磁性金属微粉末としては、強磁性六方晶フェライト微粉末や、鉄、コバルト、ニッケルやその合金からなる粉末が好ましい。前記結合剤としては熱可塑性樹脂、熱硬化性樹脂、反応型樹脂やこれらの混合物などが好ましい。
【００８４】
本発明の熱可塑性樹脂フィルムを製造するための方法においては、ポリエステルと不活性粒子、または、ポリエステルと熱可塑性樹脂のポリマーアロイを押出機を用いた溶融押出により口金から吐出し、吐出されたポリマーを冷却固化させてシート状に成形することが好ましい。その際、繊維焼結ステンレス金属フィルターによりポリマーを濾過することが、ポリマーアロイ中の未溶融物を除去するために好ましい。
【００８５】
なお、この際、押出温度においての、１，０００秒^−１における溶融粘度は２００〜１，０００Ｐａ・ｓ、さらに好ましくは４００〜８００Ｐａ・ｓである場合、不活性粒子やポリマードメインがフィルム中で整列構造をとり易く好ましい。
【００８６】
口金から吐出する際に、Ｔダイの口金ランド部の長さが１５〜４０ｍｍの範囲、口金部での剪断速度を、好ましくは３〜２００秒^−１、さらに好ましくは８〜１００秒^−１の範囲に制御すると不活性粒子やポリマードメインがフィルム中で整列構造をとり易く好ましい。
【００８７】
本発明の熱可塑性樹脂フィルムは、該シートを長手方向と幅方向の二軸に特定条件で延伸した後、熱処理することにより製造できる。この際、長手方向、および、幅方向の延伸は１段階ずつで行ってもよいが、フィルムの使用用途に応じて、２段階以上に分けて延伸してもよい。また、再縦、再横延伸を行う場合、特に高密度記録の磁気テープとして最適な高強度のフィルムが得られ易いため好ましい。
【００８８】
本発明の熱可塑性樹脂フィルムを製造する際の長手方向の総延伸倍率は、特に限定されないが、２．５〜１０倍が好ましく、より好ましくは４．５〜７倍である。長手方向の総延伸倍率が２．５倍より小さな場合は、厚みむらが悪くなったり、長手方向の弾性率が低下するため、例えば、磁気記録媒体として用いる場合、電磁変換特性が低下することがある。長手方向の総延伸倍率が１０倍より大きな場合には、フィルム破れが増加して、生産性が低下したりする。また、再縦延伸を行う際の再縦延伸倍率を総縦延伸倍率の２５％以下にする場合、フィルム破れが減少するため好ましい。再縦延伸を行う際、１度目の縦延伸の延伸倍率は２．５〜４．０倍、再縦延伸倍率は１．２〜２．３倍が好ましい。
【００８９】
本発明の熱可塑性樹脂フィルムを製造する際の幅方向の総延伸倍率は、特に限定されないが、３〜８倍が好ましく、より好ましくは３．５〜６倍である。幅方向の総延伸倍率が３倍より小さな場合は、厚みむらが悪くなったり、例えば、磁気記録媒体として用いる場合、トラックずれが起こりやすくなったりする。幅方向の総延伸倍率が６倍以上である場合、フィルム破れによって生産性が低下することがある。また、再横延伸を行う際の再横延伸倍率を総横延伸倍率の２０％以上にする場合、フィルム破れが減少するため好ましい。再横延伸を行う際、１度目の横延伸の延伸倍率は３．０〜４．５倍、再縦延伸倍率は１．２〜２倍が好ましい。
【００９０】
本発明の熱可塑性樹脂フィルムを製造する際の長手方向の延伸温度は、特に限定されないが、延伸性などの観点から、ポリマー（積層構成の場合、基層部のポリマー）のガラス転移温度Ｔｇ〜（Ｔｇ＋５０℃）の範囲で行う場合、延伸性が良好となるため好ましい。再縦延伸を行う場合、再縦延伸温度は（Ｔｇ＋３０℃）〜（Ｔｇ＋８０℃）が好ましい。
【００９１】
本発明の熱可塑性樹脂フィルムを製造する際の幅方向の延伸温度は、特に限定されないが、延伸性などの観点から、ポリマー（積層構成の場合、基層部のポリマー）のＴｇ〜（Ｔｇ＋５０℃）の範囲が好ましい。再横延伸を行う場合、再横延伸温度は（Ｔｇ＋５０℃）〜（Ｔｇ＋１５０℃）が好ましい。
【００９２】
本発明の熱可塑性樹脂フィルムを製造する際の長手方向の延伸速度は、特に限定されないが、５，０００〜２０万％／分の範囲が好ましく、再縦延伸を行う場合、再縦延伸速度は３万〜２０万％／分の範囲が好ましい。
【００９３】
本発明の熱可塑性樹脂フィルムを製造する際の幅方向の延伸速度は、特に限定されないが、１，０００〜１０，０００％／分の範囲が好ましく、再横延伸を行う場合、再横延伸速度は１，０００〜２０，０００％／分が好ましい。
【００９４】
本発明の熱可塑性樹脂フィルムを製造する際の熱処理温度は、１６０℃〜２３０℃の範囲が好ましく、より好ましくは、１８０℃〜２１０℃である。本発明の熱可塑性樹脂フィルムを製造する際の熱処理時間は、０．５〜１０秒の範囲が好ましく、より好ましくは３〜８秒である。
【００９５】
本発明の熱可塑性樹脂フィルムの延伸形式としては、長手方向に延伸した後に幅方向に延伸を行うなどの逐次二軸延伸法や、同時二軸テンター等を用いて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。
【００９６】
以下、本発明の熱可塑性樹脂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、ポリエステルとしてポリエチレンテレフタレート（ＰＥＴ）、熱可塑性樹脂として、ポリエーテルイミド（ＰＥＩ）“ウルテム”を用いたフィルムの例を示す。
【００９７】
まず、ポリエステルの製造方法をポリエチレンテレフタレートを例にして説明する。本発明で使用するポリエチレンテレフタレートは、次のいずれかのプロセスで製造される。すなわち、（１）テレフタル酸とエチレングリコールを原料とし、直接エステル化反応によって低分子量のポリエチレンテレフタレートまたはオリゴマーを得、さらにその後の三酸化アンチモンやチタン化合物を触媒に用いた重縮合反応によってポリマーを得るプロセス、（２）ジメチルテレフタレートとエチレングリコールを原料とし、エステル交換反応によって低分子量体を得、さらにその後の三酸化アンチモンやチタン化合物を触媒に用いた重縮合反応によってポリマーを得るプロセスである。ここで、エステル化は無触媒でも反応は進行するが、エステル交換反応においては、通常、マンガン、カルシウム、マグネシウム、亜鉛、リチウム、チタン等の化合物を触媒に用いて進行させ、またエステル交換反応が実質的に完結した後に、該反応に用いた触媒を不活性化する目的で、リン化合物を添加する場合もある。
【００９８】
また、フィルムを構成するポリエステルに不活性粒子を含有させる場合には、エチレングリコールに不活性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重合時に添加する方法が好ましい。不活性粒子を添加する際には、例えば、不活性粒子の合成時に得られる水ゾルやアルコールゾル状態の粒子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、不活性粒子の水スラリーを直接ＰＥＴペレットと混合し、ベント式二軸混練押出機を用いて、ＰＥＴに練り込む方法も有効である。不活性粒子の含有量を調節する方法としては、上記方法で高濃度の不活性粒子のマスターペレットを作っておき、それを製膜時に不活性粒子を実質的に含有しないＰＥＴで希釈して不活性粒子の含有量を調節する方法が有効である。
【００９９】
次に、該ＰＥＴのペレットとＰＥＩのペレットを、所定の割合で混合して、２７０〜３００℃に加熱されたベント式の二軸混練押出機に供給して、溶融押出する。このときの滞留時間は３０〜６００秒が好ましく、より好ましくは６０〜３００秒である。得られたチップを再び二軸押出機に投入し、好ましい分散径になるまで押出を繰り返してもよい。
【０１００】
得られたＰＥＩ含有のＰＥＴのペレットを、１８０℃で３時間以上減圧乾燥した後、固有粘度が低下しないように窒素気流下あるいは減圧下で、２８０〜３２０℃に加熱された押出機に供給し、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得る。この際、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。フィルムを積層する場合には、２台以上の押出機およびマニホールドまたは合流ブロックを用いて、複数の異なるポリマーを溶融積層する。
【０１０１】
次に、この未延伸フィルムを二軸延伸し、二軸配向させる。ここでは、最初に長手方向、次に幅方向の延伸を行う逐次二軸延伸法を用いる。延伸温度は、例えば、ポリエチレンテレフタレートからなる基層部とポリエチレンテレフタレートとポリエーテルイミドの混合ポリマー（混合重量比９：１）からなる積層部を有する場合を例にとって説明する。未延伸フィルムを例えば７０〜１２０℃の加熱ロール群で加熱し、長手方向に２．５〜１０倍（再際縦延伸を行う場合、２．５〜４倍）に１段もしくは多段で延伸し、２０〜５０℃の冷却ロール群で冷却する。長手方向の延伸速度は５，０００〜２００，０００％／分の範囲で行うのが好ましい。続いて、幅方向の延伸を行う。幅方向の延伸方法としては、例えば、テンターを用いる方法が一般的である。幅方向の延伸倍率は３〜８倍（再横延伸を行う場合、３〜４．５倍）、延伸速度は１，０００〜１０，０００％／分、温度は８０〜１３０℃の範囲で行うのが好ましい。さらに、再縦延伸および再横延伸を行う。その場合の延伸条件としては、長手方向の延伸は、温度８０〜１６０℃の加熱ロール群で、延伸倍率１．２〜２．３倍、幅方向の延伸方法としてはテンターを用いる方法が好ましく、温度１３０〜２３０℃、延伸倍率１．２〜２倍で行うのが好ましい。続いて、この延伸フィルムを緊張下または幅方向に弛緩しながら熱処理する。この場合の熱処理温度は、１６０℃〜２３０℃で、時間は０．５〜１０秒の範囲で行うのが好ましい。
【０１０２】
（物性の測定方法ならびに効果の評価方法）
本発明における特性値の測定方法並びに効果の評価方法は次の通りである。
【０１０３】
（１）整列構造を有する不活性粒子またはドメインの個数
フィルム表面にアルミ蒸着を行い、微分干渉顕微鏡で倍率４００〜１，０００倍でフィルム表面の観察を行い、不活性粒子またはポリマードメインが整列している方向を判別する。また、必要に応じて、ＳＥＭ、ＴＥＭや位相差顕微鏡を用いて判別を行っても良い。
【０１０４】
特に限定されないが、上記方向は、フィルムの長手方向または幅方向（フィルムの屈折率を測定した場合、最も大きな値をとる方向とその垂直方向）であることが多い。
【０１０５】
透過型電子顕微鏡（ＴＥＭ）で加圧電圧１００ｋＶの条件下でフィルム（積層フィルムであれば、本発明のフィルム層）の表層（厚み約０．５μｍ、厚み約０．５μｍ）を観察、４万倍で写真を撮影し、フィルムの上記で判別した方向を長辺とする３０μｍ×１μｍの長方形の部分中に観察される不活性粒子またはポリマードメインの個数をＮ_１とし、上記方向と垂直な方向を長辺とする３０μｍ×１μｍの長方形の部分中に観察される不活性粒子またはポリマードメインの個数をＮ_２とする。なお、観察する長方形部分（３０μｍ×１μｍ）の中心点はＴＥＭ観察部分（３０μｍ□）の中心点とする。必要に応じて、画像解析（例えば、Ｉｍａｇｅ Ｐｒｏ Ｐｌｕｓ ｖｅｒ．４．０）を用いて個数をカウントしても良い。
【０１０６】
（２）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。
【０１０７】
測定装置：オリエンテック（株）製フイルム強伸度自動測定装置
“テンシロンＡＭＦ／ＲＴＡ−１００”
試料サイズ：幅１０ｍｍ×試長間１００ｍｍ
引張り速度：２００ｍｍ／分
測定環境：温度２３℃、湿度６５％ＲＨ
（３）不活性粒子の平均粒径（またはポリマードメインのドメイン径（分散径））
フィルム断面を透過型電子顕微鏡（ＴＥＭ）を用い、１万倍以上の倍率で観察する。ＴＥＭの切片厚さは約１００ｎｍとし、場所を変えて１００視野以上測定する。測定した等価円相当径の平均を不活性粒子の平均粒径（またはポリマードメインのドメイン径（分散径））とした。
【０１０８】
フィルム中に粒径の異なる２種類以上の粒子が存在する場合、上記の等価円相当径の個数分布が２種類以上のピークを有する分布となるため、そのそれぞれについて、別個に平均粒径を算出する。
【０１０９】
（４）ポリエステル、熱可塑性樹脂、不活性粒子の含有量
ポリエステル、熱可塑性樹脂の両者を溶解する適切な溶媒に溶解し、^１Ｈ核のＮＭＲ（核磁気共鳴）スペクトルを測定する。適切な溶媒は、ポリマーの種類によって異なるが、例えば、ヘキサフルオロイソプロパノール（ＨＦＩＰ）／重クロロホルムが用いられる。得られたスペクトルにおいて、ポリエステル、熱可塑性樹脂に特有の吸収（例えばＰＥＴであればテレフタル酸の芳香族プロトンの吸収、ＰＥＩであればビスフェノールＡの芳香族のプロトンの吸収）のピーク面積強度をもとめ、その比率とプロトン数よりポリエステルと熱可塑性樹脂のモル比を算出する。さらに各々のポリマーの単位ユニットに相当する式量より重量比を算出する。測定条件は、例えば、以下のような条件であるが、ポリマーの種類によって異なるため、この限りではない。
【０１１０】
装置 ：ＢＲＵＫＥＲ ＤＲＸ−５００（ブルカー社）
溶媒 ：ＨＦＩＰ／重クロロホルム
観測周波数 ：４９９．８ＭＨｚ
基準 ：ＴＭＳ（テトラメチルシラン）（０ｐｐｍ）
測定温度 ：３０℃
観測幅 ：１０ＫＨｚ
データ点 ：６４Ｋ
ａｃｑｕｉｓｉｔｏｎ ｔｉｍｅ ：４．９５２秒
ｐｕｌｓｅ ｄｅｌａｙ ｔｉｍｅ：３．０４８秒
積算回数 ：２５６回
また、必要に応じて、顕微ＦＴ−ＩＲ法（フーリエ変換顕微赤外分光法）で組成分析を行ってもよい。その場合、ポリエステルのカルボニル基に起因するピークとそれ以外の物質に起因するピークの比から求める。なお、ピーク高さ比を重量比に換算するために、あらかじめ重量比既知のサンプルで検量線を作成してポリエステルとそれ以外の物質の合計量に対するポリエステル比率を求める。これと、不活性粒子含有量より熱可塑性樹脂の比率を求める。また、必要に応じてＸ線マイクロアナライザーを併用してもよい。
【０１１１】
また、不活性粒子の含有量については、ポリエステル、熱可塑性樹脂は溶解するが不活性粒子は溶解させない溶媒を選んで、ポリエステル、熱可塑性樹脂を溶解し、不活性粒子を遠心分離して重量百分率を求めた。
【０１１２】
（５）積層厚さ
透過型電子顕微鏡（日立製Ｈ−６００型）を用いて、加速電圧１００ｋＶで、フィルム断面を、超薄切片法（ＲｕＯ_４染色）で観察する。その界面の観察結果から、各層の厚さを求める。倍率は、判定したい積層厚さによって適切な倍率を選ぶが、１万〜１０万倍が適当である。
【０１１３】
また、２次イオン質量分析装置（ＳＩＭＳ）を用いて測定することもできる。表層から深さ３，０００ｎｍの範囲のフィルム中の不活性粒子の内、最も高濃度の粒子（あるいはＰＥＩ）に起因する元素と、ポリエステルの炭素元素の濃度比（Ｍ^＋／Ｃ^＋）を、表面から深さ３，０００ｎｍまで厚さ方向にＳＩＭＳで分析する。表層では不活性粒子に起因する元素濃度は低く、表面から遠ざかるにつれて不活性粒子に起因する元素濃度は高くなる。本発明フィルムの場合は一旦極大値となった不活性粒子に起因する元素濃度がまた減少し始める。この濃度分布曲線において、不活性粒子に起因する元素濃度が極大値の１／２まで減少した深さを積層厚さとする。条件は次の通りである。
【０１１４】
ｉ）測定装置
２次イオン質量分析装置（ＳＩＭＳ）
西独、ＡＴＯＭＩＫＡ社製 Ａ−ＤＩＤＡ３０００
ｉｉ）測定条件
１次イオン種 ：Ｏ_２ ^＋
１次イオン加速電圧：１２ＫＶ
１次イオン電流 ：２００ｎＡ
ラスター領域 ：４００μｍ□
分析領域 ：ゲート３０％
測定真空度 ：５．０×１０^−９Ｔｏｒｒ
Ｅ−ＧＵＮ ：０．５ＫＶ−３．０Ａ
なお、表層から深さ３，０００ｎｍの範囲に最も多く含有する不活性粒子が有機高分子粒子の場合はＳＩＭＳでは測定が難しいので、表面からエッチングしながらＸＰＳ（Ｘ線光電子分光法）、ＩＲ（赤外分光法）などで上記同様のデプスプロファイルを測定し積層厚みを求めることもできる。
【０１１５】
（６）表面粗さＲａ
小坂研究所製の高精度薄膜段差測定器ＥＴ−１０を用いて中心線平均粗さＲａを測定した。条件は下記のとおりであり、フィルム幅方向に走査して２０回測定を行った平均値をもって値とした。なお、積層フィルムの場合、本願のフィルム層側の表面の表面粗さをＲａ_（１）、反対側の表面の表面粗さをＲａ_（２）とする。
【０１１６】
・触針先端半径：０．５μｍ
・触針荷重 ：５ｍｇ
・測定長 ：１ｍｍ
・カットオフ値：０．０８ｍｍ
（７）溶融粘度
メルトインデクサを用いて、剪断速度１，０００秒^−１の時の粘度を測定した。
【０１１７】
（８）ガラス転移温度（Ｔｇ）
下記装置および条件で比熱測定を行い、ＪＩＳ Ｋ７１２１に従って決定した。
【０１１８】
装置 ：ＴＡ Ｉｎｓｔｒｕｍｅｎｔ社製温度変調ＤＳＣ
測定条件：
加熱温度 ：２７０〜５７０Ｋ（ＲＣＳ冷却法）
温度校正 ：高純度インジウムおよびスズの融点
温度変調振幅：±１Ｋ
温度変調周期：６０秒
昇温ステップ：５Ｋ
試料重量 ：５ｍｇ
試料容器 ：アルミニウム製開放型容器（２２ｍｇ）
参照容器 ：アルミニウム製開放型容器（１８ｍｇ）
なお、ガラス転移温度は下記式により算出した。
【０１１９】
ガラス転移温度＝（補外ガラス転移開始温度＋補外ガラス転移終了温度）／２
（９）口金部分の剪断速度
下記式に従って求める。
【０１２０】
Ｊ＝６Ｑ／ｗｔ^２
ここで、Ｊ：剪断速度（ｓｅｃ^−１）
Ｑ：流量（ｇ／ｓｅｃ）
ｗ：口金幅（ｃｍ）
ｔ：スリット幅（ｃｍ）
（１０）不活性粒子またはポリマードメインの整列度合い（Ｎ_１／Ｎ_２）
前記（１）の測定方法に従い、３０点観察を行い、３０組のＮ_１、Ｎ_２を求め、比Ｎ_１／Ｎ_２を算出する。このとき、以下の関係を満たすＮ_１／Ｎ_２が３０点中１５点以上であった場合、フィルム中で不活性粒子またはポリマードメインが１方向に整列している（整列構造を有している）と判定する。
【０１２１】
Ｎ_１＞Ｎ_２の場合、Ｎ_１／Ｎ_２＞１．３
Ｎ_２＞Ｎ_１の場合、Ｎ_２／Ｎ_１＞１．３
（１１）磁気テープの耐転写性
１ｍ幅にスリットしたフィルムを、張力２０ｋｇ／ｍで搬送させ、フィルムの不活性粒子またはポリエステル以外の熱可塑性樹脂からなるドメインが整列している側と反対側の表面に下記組成の磁性塗料および非磁性塗料をエクストルージョンコーターにより重層塗布（上層は磁性塗料で、塗布厚０．１μｍ、非磁性下層の厚みは適宜変化させた。）し、磁気配向させ、乾燥温度１００℃で乾燥させる。次いで反対側の表面（不活性粒子またはポリエステル以外の熱可塑性樹脂からなるドメインが整列している側の表面）に下記組成のバックコートを塗布した後、小型テストカレンダー装置（スチール／ナイロンロール、５段）で、温度８５℃、線圧２００ｋｇ／ｃｍでカレンダー処理した後、巻き取る。上記テープ原反を１／２インチ幅にスリットし、長さ５００ｍ分を張力１０ＭＰａで巻き取って、パンケーキを作成した。次いで、このパンケーキからの表層（パンケーキ外側の端から１０ｍの部分）と巻芯（パンケーキ巻芯の端から１０ｍの部分）をサンプリングし、（６）の測定方法に従って、磁性面側の表面粗さＲａを測定した。巻芯の表面粗さＲａ（巻芯）と表層の表面粗さＲａ（表層）の差、表面粗さＲａ（巻芯）−表面粗さＲａ（表層）が３ｎｍ以下の場合、耐転写性良好と判断し、３ｎｍより大きい場合は、耐転写性不良と判断した。
（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
（１２）磁気テープの高速走行安定性
前記（１１）で加工した磁気テープをテープ走行性試験機ＴＢＴ−３００型（（株）横浜システム研究所製）を使用し、６０℃、８０％ＲＨ雰囲気で、片端に位置規制板を有するガイドピン（ＳＵＳ２７、６ｍｍφ、巻き付け角９０°）上を、速度１０ｍ／秒、張力５Ｎの条件で、５００ｍ走行させ、レーザー寸法測定器を用いて、位置規制板と反対側のテープエッジの初期位置からの変位を読みとり、最大変位量（μｍ）を測定した。最大変位量が５μｍ以下であれば、高速走行安定性が良好であると判断する。
【０１２２】
（１３）直線引裂性
フィルムの長手方向に３００ｍｍ、幅方向に２０ｍｍの短冊状のフィルム片を切り出し、このフィルム片の一方の短辺の中央部に長さ５ｍｍの切れ込みを入れた試料を１０本作成した。次に、切れ込みより長手方向に手で引裂き、切れ込みを入れた辺に向かい合う短辺に到達したときを長手方向の直線引裂性を良好として、短辺に到達せず途中で長辺に達したときを長手方向の直線引裂性を不良とした。１０本の試料を評価して、５本以上の試料の直線引裂性が良好であれば直線引裂性良好、４本以下であれば不良とした。
【０１２３】
【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。なお、ここでポリエチレンテレフタレートをＰＥＴ、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との縮合物であるポリエーテルイミドをｍ−ＰＥＩ、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ｐ−フェニレンジアミンとの縮合物であるポリエーテルイミドをｐ−ＰＥＩ、ポリカーボネートをＰＣと表記する。
【０１２４】
実施例１
テレフタル酸ジメチル１９４重量部とエチレングリコール１２４重量部に、酢酸マグネシウム４水塩０．１重量部を加え、１４０〜２３０℃でメタノールを留出しつつエステル交換反応を行った。次いで、リン酸トリメチル０．０５重量部のエチレングリコール溶液、および三酸化アンチモン０．０５重量部を加えて５分間撹拌した後、低重合体を３０ｒｐｍで攪拌しながら、反応系を２３０℃から２９０℃まで徐々に昇温するとともに、圧力を０．１ｋＰａまで下げた。最終温度、最終圧力到達までの時間はともに６０分間とした。３時間重合反応させ所定の攪拌トルクとなった時点で反応系を窒素パージし常圧に戻して重縮合反応を停止し、冷水にストランド状に吐出し、直ちにカッティングして固有粘度０．６２のポリエチレンテレフタレート（ＰＥＴ）のペレットを得た。該ＰＥＴのペレットのガラス転移温度は７８℃であった。
【０１２５】
得られたポリエチレンテレフタレートのペレット（温度１８０℃で３時間減圧乾燥）を５０重量％と、Ｇｅｎｅｒａｌ Ｅｌｅｃｔｒｉｃ（ＧＥ）社製ｍ−ＰＥＩ“ウルテム１０１０”２５重量％と、ＧＥ社製ｐ−ＰＥＩ“ウルテム５００１”２５重量％を、３００℃に加熱されたベント式の二軸混練押出機に供給して、溶融押出し、ｍ−ＰＥＩを２５重量％、ｐ−ＰＥＩを２５重量％含有するＰＥＴ／ＰＥＩのペレットを作成した。
【０１２６】
温度２８０℃に加熱された押出機に、得られたＰＥＴ／ＰＥＩのペレット４０重量部とポリエチレンテレフタレートのペレット６０重量部（ｍ−ＰＥＩ含有量１０重量％、ｐ−ＰＥＩ含有量１０重量％）を１８０℃で３時間減圧乾燥した後に供給し、Ｔダイにより溶融押出した（口金ランド長３０ｍｍ）。この時の溶融押出における滞留時間は３分間、口金での剪断速度は１２ｓｅｃ^−１であった。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シートを密着させて冷却固化し、厚み１５０μｍの未延伸熱可塑性樹脂フィルム（Ｔｇは９５℃であった）を作成した。
【０１２７】
この未延伸フィルムをロール式延伸機にて長手方向に２段で、速度２０，０００％／分、温度７０℃から１１０℃で３．０倍延伸し、さらに、テンターを用いて、幅方向に速度２，０００％／分、温度１１５℃で３．５倍延伸した。続いて、ロール式延伸機で長手方向に１段で、温度８０℃から１６５℃で１．５倍に再延伸した後、定長下で温度２０５℃で３秒間熱処理後、幅方向に５％の弛緩処理を施し、厚さ８μｍの二軸配向熱可塑性樹脂フィルムを得た。
【０１２８】
この二軸配向熱可塑性樹脂フィルムは表１のとおり、長手方向のヤング率は６ＧＰａ、幅方向のヤング率は４ＧＰａ、表面粗さは表裏とも９ｎｍであった。また、２８０℃、１，０００秒^−１におけるフィルムの溶融粘度は６００Ｐａ・ｓであり、Ｎ_１／Ｎ_２の値も本願の範囲を満たすものであった。
【０１２９】
比較例１
実施例１と同様にして得た実質的に粒子を含有しないＰＥＴのペレット（Ｔｇ８０℃）５０重量部と平均粒径０．１μｍの架橋ジビニルベンゼン粒子を２重量％含有するＰＥＴペレットを１８０℃で３時間減圧乾燥した後に押出機に供給し、実施例１と全く同様にして、厚み１５０μｍの未延伸熱可塑性樹脂フィルム（Ｔｇは８０℃であった）を作成した。
【０１３０】
この未延伸フィルムをロール式延伸機にて長手方向に、温度９５℃で３．０倍延伸し、さらに、テンターを用いて、幅方向に温度１００℃で３．５倍延伸した。続いて、ロール式延伸機にて長手方向に、温度１６５℃で１．５倍延伸した後、定長下で温度２０５℃で３秒間熱処理後、幅方向に５％の弛緩処理を施し、厚さ８μｍの二軸配向熱可塑性樹脂フィルムを得た。
【０１３１】
この二軸配向熱可塑性樹脂フィルムは表１のとおり、長手方向のヤング率は７ＧＰａ、幅方向のヤング率は４ＧＰａ、表面粗さは表裏とも９ｎｍであった。また、２８０℃、１，０００秒^−１におけるフィルムの溶融粘度は１５０Ｐａ・ｓであり、Ｎ_１／Ｎ_２の値は本願の範囲を満たさなかった。また、表１に示すとおり、磁気テープに加工した際の、高速走行安定性も実施例１対比劣るものであった。
【０１３２】
実施例２
実施例１と同様にして、得たＰＥＴのペレット（Ｔｇ８０℃）５０重量％とＧＥ社製の“ウルテム”１０１０（Ｔｇ２１６℃）５０重量％を、２９０℃に加熱された同方向回転タイプのベント式二軸混練押出機に供給して、ＰＥＩを５０重量％含有したＰＥＴ／ＰＥＩブレンドチップを作成した。
【０１３３】
次いで、押出機２台を用い、製膜を行った。
【０１３４】
２８０℃に加熱された押出機１（積層部用）には、上記のＰＥＴ／ＰＥＩブレンドチップを４０重量部と、平均粒径５０ｎｍの球状シリカ粒子を２０重量％含有する固有粘度０．８５のＰＥＴペレット６０重量部の混合原料（２８０℃、１０００秒^−１における溶融粘度は４００Ｐａ・ｓ）を１８０℃で３時間減圧乾燥した後に供給した。
【０１３５】
２９５℃に加熱された押出機２（基層部用）には、平均粒径５０ｎｍのシリカを１重量％含有する固有粘度０．６１のＰＥＴペレット５重量部と、実質的に粒子を含有しない固有粘度０．６１のＰＥＴペレット９５重量部の混合原料をを１８０℃で３時間減圧乾燥した後に供給した。
【０１３６】
これらをそれぞれ、サンドフィルター、繊維焼結ステンレス金属フィルターの順に濾過した後、Ｔダイ中で合流させ、実施例１と同様にして、２層積層未延伸フィルム（積層厚み比：積層部／基層部＝１／５）を作成した。
【０１３７】
この未延伸フィルムを同時二軸テンターを用いて、長手・幅方向に同時で速度２，０００％／分、温度１００℃で長手方向４倍、幅方向４倍延伸した。続いて、同時二軸テンターを用いて、長手に速度２，０００％／分、温度１５０℃で長手方向１．５倍延伸した後、定長下で温度２２０℃で５秒間熱処理した後、幅方向に５％の弛緩処理を行い、厚さ約６μｍの二軸配向熱可塑性フィルムを作成した。
【０１３８】
各層のフィルム厚みは、基層部５μｍ、積層部（本発明のフィルム層）１μｍであった。長手方向のヤング率は７ＧＰａ、幅方向のヤング率は５ＧＰａであった。
【０１３９】
この熱可塑性樹脂フィルムは、表２に示したとおり、Ｎ_１／Ｎ_２の値が本願の範囲を満たすものであった。また、表３に示したとおり、磁気テープに加工した際の高速走行安定性、耐転写性に優れたフィルムであった。
【０１４０】
実施例３
得られたポリエチレンテレフタレートのペレット（温度１８０℃で３時間減圧乾燥）を７０重量％と、芳香族ポリカーボネートのペレット“ユーピロン”（登録商標）Ｓ−２０００（三菱エンジニアプラスチック社製：ガラス転移温度１５０℃）（温度１２０℃で３時間減圧乾燥）３０重量％を配合し、２８０℃に加熱されたベント式の二軸混練押出機に供給して、溶融押出し、芳香族ポリカーボネートを３０重量％含有するＰＥＴ／ＰＣのペレットを作成した。得られたペレットは透明であった（２８０℃、１，０００秒^−１における溶融粘度は８００Ｐａ・ｓ）。
【０１４１】
続いて、押出機２台を用いて、製膜を行った。
【０１４２】
温度２８０℃に加熱された押出機１には、得られたＰＥＴ／ＰＣのペレット３０重量部とポリエチレンテレフタレートのペレット７０重量部（ＰＣ含有量９重量％）を１８０℃で３時間減圧乾燥した後に供給し、押出機２には実施例２と全く同様の原料を供給した。 これらをそれぞれ、サンドフィルター、繊維焼結ステンレス金属フィルターの順に濾過した後、Ｔダイ中で合流させ、実施例１と同様にして、２層積層未延伸フィルム（積層厚み比：積層部／基層部＝１／３）を作成した。
【０１４３】
この未延伸フィルムをロール式延伸機にて長手方向に２段で、速度２０，０００％／分、温度７０℃から１０５℃で３．５倍延伸し、さらに、テンターを用いて、幅方向に速度２，０００％／分、温度１１０℃で４．２倍延伸した後、定長下で温度２２０℃で５秒間熱処理した後、幅方向に５％の弛緩処理を行い、厚さ約８μｍの積層ポリエステルフィルムを作成した。
【０１４４】
各層のフィルム厚みは、基層部６μｍ、積層部（本発明のフィルム層）２μｍであった。長手方向のヤング率は４ＧＰａ、幅方向のヤング率は６．２ＧＰａであった。
【０１４５】
この熱可塑性樹脂フィルムは、表２に示したとおり、Ｎ_１／Ｎ_２の値が本願の範囲を満たすものであった。また、表３に示したとおり、磁気テープに加工した際の高速走行安定性、耐転写性に優れたフィルムであった。
【０１４６】
比較例２
積層部原料を表２に示したように変更し、積層原料の溶融粘度（２８０℃、１，０００秒^−１）を２５０Ｐａ・ｓとすること以外は、実施例２と全く同様にして、厚さ約６μｍの二軸配向熱可塑性フィルムを作成した。
【０１４７】
各層のフィルム厚みは、基層部５μｍ、積層部１μｍであった。長手方向のヤング率は７ＧＰａ、幅方向のヤング率は５ＧＰａであった。
【０１４８】
この熱可塑性樹脂フィルムは、表２に示したとおり、Ｎ_１／Ｎ_２の値が本願の範囲を満たさなかった。また、表３に示したとおり、磁気テープに加工した際の耐転写性が実施例対比劣るフィルムであった。
【０１４９】
比較例３
積層部原料にＰＥＩを含有せず、固有粘度０．５８のＰＥＴ原料を使用することによって積層原料の溶融粘度（２８０℃、１，０００秒^−１）を１００Ｐａ・ｓに変更し、また、表２に示すように、粒子種、粒子含有量を変更して、実施例３と同様にして、２層積層未延伸フィルム（積層厚み比：積層部／基層部＝１／３）を作成した。
【０１５０】
この未延伸フィルムを実施例３と全く同様にして、延伸・熱処理を行い、厚さ約８μｍの積層ポリエステルフィルムを作成した。
【０１５１】
各層のフィルム厚みは、基層部６μｍ、積層部２μｍであった。長手方向のヤング率は４．２ＧＰａ、幅方向のヤング率は６．３ＧＰａであった。
【０１５２】
この熱可塑性樹脂フィルムは、表２に示したとおり、Ｎ_１／Ｎ_２の値が本願の範囲を満たさなかった。また、表３に示したとおり、磁気テープに加工した際の高速走行安定性、耐転写性が実施例対比劣るフィルムであった。
【０１５３】
実施例４
実施例１と同様のｍ−ＰＥＩとｐ−ＰＥＩを１：３の割合でＮメチルピロリドン（ＮＭＰ）に溶解させた後、溶媒を揮発させて、ｍ−ＰＥＩとｐ−ＰＥＩを１：３の割合で含むＰＥＩペレットを作成した。
【０１５４】
上記ＰＥＩペレット４０重量部と実施例１と同様にして得られた固有粘度０．８５のＰＥＴペレット６０重量％を３００℃に加熱されたベント式の二軸混練押出機に供給して溶融押出し、ｍ−ＰＥＩを１０重量％、ｐ−ＰＥＩを３０重量％含有するＰＥＴ／ＰＥＩのペレットを作成した。
【０１５５】
続いて押出機２台を用いて製膜を行った。
【０１５６】
温度２８０℃に加熱された押出機１（基層部用）には、上記ＰＥＴ／ＰＥＩのペレット５０重量部とポリエチレンテレフタレートのペレット５０重量部の混合原料（Ｔｇ９５℃、２８０℃、１，０００秒^−１における溶融粘度は５００Ｐａ・ｓ）を１８０℃で３時間減圧乾燥した後に供給し、押出機２（積層部用）には表２に示す様に、平均粒径０．３μｍの架橋ジビニルベンゼンを１重量％含有する固有粘度０．６０のＰＥＴ原料を供給した。
【０１５７】
これらをそれぞれ、サンドフィルター、繊維焼結ステンレス金属フィルターの順に濾過した後、Ｔダイ中で合流させ、実施例１と同様にして、３層積層未延伸フィルム（積層厚み比：積層部／基層部／積層部＝１／４８／１）を作成した。
【０１５８】
この未延伸フィルムをロール式延伸機にて長手方向に２段で、速度２０，０００％／分、温度７０℃から１１５℃で３倍延伸し、さらに、テンターを用いて、幅方向に速度２，０００％／分、温度１１０℃で３倍延伸した後、定長下で温度２４０℃で５秒間熱処理し、厚さ約５０μｍの積層ポリエステルフィルムを作成した。
【０１５９】
各層のフィルム厚みは、基層部４８μｍ（本発明のフィルム層）、積層部はそれぞれ１μｍであった。長手方向のヤング率は４．１ＧＰａ、幅方向のヤング率は４．２ＧＰａであった。
【０１６０】
この熱可塑性樹脂フィルムは、表２に示したとおり、Ｎ_１／Ｎ_２の値が本願の範囲を満たすものであった。また、表４に示したとおり、直線引裂性の良好なフィルムであった。
【０１６１】
比較例４
表２に示すように、基層部の原料として、実質的に粒子を含有しない固有粘度０．６５のＰＥＴ原料（Ｔｇ８０℃、２８０℃、１，０００秒^−１における溶融粘度は１５０Ｐａ・ｓ）を用いる以外は、実施例４と全く同様にして、３層積層未延伸フィルム（積層厚み比：積層部／基層部／積層部＝１／４８／１）を作成した。
【０１６２】
この未延伸フィルムをロール式延伸機にて長手方向に２段で、速度２０，０００％／分、温度７０℃から９５℃で３倍延伸し、さらに、テンターを用いて、幅方向に速度２，０００％／分、温度１００℃で３倍延伸した後、定長下で温度２４０℃で５秒間熱処理し、厚さ約５０μｍの積層ポリエステルフィルムを作成した。
【０１６３】
各層のフィルム厚みは、基層部４８μｍ、積層部はそれぞれ１μｍであった。長手方向のヤング率は４．５ＧＰａ、幅方向のヤング率は４．５ＧＰａであった。
【０１６４】
この熱可塑性樹脂フィルムは、表２に示したとおり、Ｎ_１／Ｎ_２の値が本願の範囲を満たさなかった。また、表４に示したとおり、直線引裂性の劣るフィルムであった。
【０１６５】
【表１】

【０１６６】
【表２】

【０１６７】
【表３】

【０１６８】
【表４】

【０１６９】
【発明の効果】
本発明によれば、フィルム中に粒子またはポリマードメインが整列した構造を形成することによって、表層に微細なすじ状の構造を形成し、転写が起こりにくく、また、高速で走行させた場合の安定性に優れた磁気記録装置用磁気テープのベースフィルムとして高品質のポリエステルフィルムを得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention has domains and inert particles having an aligned structure on the film surface, and particularly when used as a substrate for a high-density magnetic recording medium, there is little transfer to opposite surfaces such as protrusions, and running characteristics. It is related with the thermoplastic resin film which improved significantly.
[0002]
[Prior art]
Polyester films are used in various applications because of their excellent thermal properties, dimensional stability, mechanical properties, and ease of control of surface morphology, and their usefulness as base films, especially for magnetic tapes, is well known. . In recent years, magnetic tapes have been required to have high density recording in order to reduce the weight, size, and recording time of equipment. In order to achieve high density recording, it is effective to shorten the recording wavelength and increase the recording density.
[0003]
In the above-mentioned base film for a magnetic recording medium, generally, the surface on the magnetic recording surface side (hereinafter referred to as a magnetic surface) is required to be a smooth surface for the purpose of improving electromagnetic conversion characteristics. On the other hand, the surface opposite to the magnetic surface side (hereinafter referred to as the traveling surface) has a certain degree of roughness in order to improve the transportability of the base film in the film forming and processing process and the traveling property of the magnetic tape in the drive. It is necessary to have.
[0004]
As described above, in terms of controlling the surface properties of the film, conventionally, a laminated polyester film containing particles for forming surface protrusions, a method of coating a discontinuous film containing fine particles, and the like are known. (Patent Documents 1 and 2).
[0005]
Alternatively, a technique is known in which two or more kinds of polymers are blended without adding particles and the polymer is finely dispersed in the matrix polymer (Patent Documents 3 and 4).
[0006]
However, in response to the trend toward higher recording density, the smoothness on the magnetic side has been abruptly progressing, and the surface roughness on the magnetic recording surface side and the running surface side have been greatly different. In the production process of the base film and the magnetic tape processing process, there is a problem that the protrusion on the traveling surface side “transfers” to the magnetic surface side and the magnetic surface side becomes rough. In addition, in order to cope with this problem, when the running surface side is smoothed, when the magnetic tape is used, the friction between the guide rolls becomes high and air leakage becomes worse, so that the tape is scraped. It may become easier, and poor running such as tape meandering may occur.
[0007]
For this reason, a base film for a magnetic recording medium in particular has been required to have a smooth surface that is difficult to transfer to a mating member while having a certain degree of running performance.
[0008]
[Patent Document 1] Japanese Patent Laid-Open No. 7-272249
[0009]
[Patent Document 2] JP-A-3-208639
[0010]
[Patent Document 3] JP 2001-329077 A
[0011]
[Patent Document 4] Japanese Patent Application Laid-Open No. 2003-4913
[0012]
[Problems to be solved by the invention]
The object of the present invention is to form a line-like alignment structure on the surface of the film by forming particles and polymer domains in the film in a line shape, which has excellent runnability and abrasion resistance, and less magnetic transfer. An object of the present invention is to provide a biaxially oriented thermoplastic resin film that is excellent as a base film for recording media or a thermoplastic resin film that is excellent as a packaging application that can be easily cut in the line direction.
[0013]
[Means for Solving the Problems]
The present invention is characterized by a thermoplastic resin film containing 50% by weight or more of polyester and having a domain having an aligned structure in at least one direction in the plane direction.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic resin film of the present invention can be used in any orientation form of unstretched, uniaxial orientation, and biaxial orientation. For example, when used for magnetic recording media, it is a biaxially oriented film. It is preferable. When the film has a laminated structure of two or more layers, it is preferable that at least one of the film layers constituting the film is biaxially oriented.
[0015]
The thermoplastic resin film of the present invention contains 50% by weight or more of the polyester weight. Of course, it may be composed substantially only of polyester, or may contain a thermoplastic resin other than polyester.
[0016]
The polyester used in the thermoplastic resin film of the present invention is a polymer composed of an acid component such as aromatic dicarboxylic acid, alicyclic dicarboxylic acid or aliphatic dicarboxylic acid and a diol component.
[0017]
As the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like can be used. As alicyclic dicarboxylic acid, cyclohexane dicarboxylic acid etc. can be used, for example. As the aliphatic dicarboxylic acid, for example, adipic acid, sebacic acid, dodecanedioic acid and the like can be used. Of these, terephthalic acid, 2,6-naphthalenedicarboxylic acid and the like can be preferably used, and terephthalic acid can be particularly preferably used. These acid components may be used alone or in combination of two or more.
[0018]
Examples of the diol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, Triethylene glycol, 2,2′-bis (4′-β-hydroxyethoxyphenyl) propane and the like can be used, and ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol are particularly preferable. Diethylene glycol or the like can be used, and ethylene glycol can be used particularly preferably. These diol components may be used alone or in combination of two or more.
[0019]
Examples of the polyester used in the present invention include polyethylene terephthalate (PET) and poly (ethylene-2,6-naphthalenedicarboxylate) (PEN), and from the viewpoint of melt moldability, most preferably polyethylene terephthalate ( PET).
[0020]
When the polyester used in the present invention is a polyester having ethylene terephthalate as a main constituent, the polyester may be either a direct weight method or a DMT method, but calcium acetate may be used as a transesterification catalyst in the DMT method. preferable. In the polymerization stage, although not particularly limited, it is preferable to use a germanium compound as a polymerization catalyst in order to reduce coarse protrusions due to foreign matters. Examples of the germanium catalyst include (1) amorphous germanium oxide, (2) crystalline germanium oxide having an average particle size of 5 μm or less, and (3) germanium oxide in the presence of an alkali metal, an alkaline earth metal, or a compound thereof. A solution dissolved in glycol, and (4) a solution of germanium oxide in which germanium oxide is dissolved in water and then glycol is added to distill off the water are used.
[0021]
Polyesters include trimellitic acid, pyromellitic acid, glycerol, pentaerythritol, polyfunctional compounds such as 2,4-dioxybenzoic acid, monofunctional compounds such as lauryl alcohol and phenyl isocyanate, p-hydroxybenzoic acid, Copolymerization of aromatic hydroxycarboxylic acid such as m-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid, p-aminophenol, p-aminobenzoic acid, etc., in an amount that does not impair the effects of the present invention. May be.
[0022]
The thermoplastic resin film of the present invention may contain an inert particle or a thermoplastic resin other than polyester in addition to the polyester.
[0023]
When the thermoplastic resin film of the present invention contains inert particles and the inert particles are used as an aligned structure, the inert particles are inorganic or organic particles having an average particle diameter of about 1 nm to 5 μm. A polymer that does not cause a chemical reaction in the polymer used or does not adversely affect magnetic recording due to electromagnetic influence. Inactive particles include titanium oxide, calcium carbonate, kaolin, talc, wet or dry silica, colloidal silica, calcium phosphate, barium sulfate, alumina, zirconia, and other inorganic particles, acrylic acids, styrene, silicone, imide, etc. Organic particles, particles precipitated by a catalyst added during the polyester polymerization reaction (so-called internal particles), surfactants, and the like.
[0024]
When the thermoplastic resin film of the present invention contains inert particles, the average particle size and content of the inert particles vary greatly depending on the film application and the laminated structure, but when the average particle size is 10 nm to 1 μm, the inert particles Is preferable because it is easy to take an aligned structure. Most preferably, it is 50 nm-0.5 micrometer.
[0025]
When the thermoplastic resin film of the present invention contains inert particles and the inert particles are used as an aligned structure, the content of the inert particles varies depending on the particle size of the inert particles, but is 5 to 15% by weight. Preferably, it is 7 to 12% by weight. In the case of this content, the particles are easily aligned. In this case, it is preferable to use polyethylene terephthalate as the polyester. The inert particles are preferably at least one particle selected from the group consisting of crosslinked polystyrene, silica, alumina and silicone.
[0026]
Moreover, one type of inert particle may be included in each film layer, but two or more types may be used in combination.
[0027]
When the thermoplastic resin film of the present invention contains a thermoplastic resin other than polyester, the thermoplastic resin other than polyester is a thermoplastic resin having melt moldability at a temperature of 200 to 350 ° C. when mixed with polyester. It is preferable.
[0028]
The thermoplastic resin other than polyester is preferably formed so that the phase separation structure (domain) of the sea-island structure has an aligned structure in at least one of the plane directions when melt-mixed with the polyester. The diameter of this domain is preferably 10 nm to 1 μm. The domain diameter is more preferably 30 nm to 0.5 μm, and most preferably 50 nm to 0.3 μm. The domain diameter here refers to, for example, a polymer alloy made of polyester and a thermoplastic resin other than polyester, and an unstretched or biaxially stretched film is prepared, and the film cross section is 30,000 to 500,000 with a transmission electron microscope. The equivalent circle diameter of the structure observed when observed at double magnification. When the domain diameter is smaller than 10 nm, the domains are not only difficult to align, but also when aligned, the influence on the film physical properties may be small. When the domain diameter is larger than 1 μm, it is caused by phase separation. Film-breaking may occur frequently or the manufactured film may become brittle.
[0029]
As a thermoplastic resin other than polyester in the present invention, when a heat-resistant resin having a glass transition temperature (Tg) higher than that of polyester is used, a film having high dimensional stability and heat resistance can be obtained. preferable.
[0030]
The thermoplastic resin other than polyester that satisfies the above conditions is preferably exemplified by at least one thermoplastic resin selected from the group consisting of polycarbonate, polyimide, polysulfone, and polyethersulfone, although it varies depending on the type of polyester.
[0031]
The polycarbonate used as the thermoplastic resin other than polyester is particularly preferably an aromatic polycarbonate, and is not particularly limited. However, bisphenol A, that is, 2,2′-bis (4-hydroxyphenyl) propane, 4,4′- Preferable examples include those containing one or more selected from dihydroxydiphenylalkane, 4,4′-dihydroxydiphenylsulfone, and 4,4′-dihydroxydiphenyl ether as main raw materials, and bisphenol A, that is, 2,2 ′ Those produced using bis (4-hydroxyphenyl) propane as the main raw material are preferred. Specifically, polycarbonate obtained by the transesterification method or the phosgene method using the above bisphenol A or the like as a dihydroxy component is preferable. Further, a part of bisphenol A, preferably 10 mol% or less substituted with 4,4′-dihydroxydiphenylalkane or 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenyl ether, or the like is also preferable. .
[0032]
These may be present alone or in combination of two or more in the polymer chain as long as the effects of the present invention are not impaired.
[0033]
Although the said polyimide used as thermoplastic resins other than polyester will not be specifically limited if it is melt moldability, For example, what contains a structural unit as shown by the following general formula is preferable.
[0034]
[Chemical 2]

[0035]
However, R in the formula¹Is
[0036]
[Chemical 3]

[0037]
[Formula 4]

[0038]
Represents one or more groups selected from an aliphatic hydrocarbon group such as, an alicyclic hydrocarbon group, an aromatic hydrocarbon group,
R in the formula²Is
[0039]
[Chemical formula 5]

[0040]
Represents one or two or more groups selected from an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.
[0041]
Such a polyimide dehydrates one or more compounds selected from the group consisting of tetracarboxylic acid and / or its anhydride and an aliphatic primary monoamine, aromatic primary monoamine, aliphatic primary diamine and aromatic primary diamine. It can be obtained by condensation.
[0042]
From the viewpoints of melt moldability with polyester, handleability, and formation of surface protrusions, a polyetherimide containing an ether bond in the polyimide component as shown by the following general formula is particularly preferred.
[0043]
[Chemical 6]

[0044]
(However, in the above formula, R³Is a divalent aromatic or aliphatic residue having 6 to 30 carbon atoms, R⁴Is 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. )
R above³, R⁴As, for example, an aromatic residue represented by the following formula group
[0045]
[Chemical 7]

[0046]
Can be mentioned. (Where n is an integer from 1 to 5)
In the present invention, 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride and m-phenylenediamine or p from the viewpoint of affinity with polyester, cost, melt moldability, and the like. A polymer having a repeating unit represented by the following formula, which is a condensate with -phenylenediamine, is preferable, and a condensate with p-phenylenediamine is particularly preferable from the viewpoint of easy formation of a phase separation domain with polyester. In addition, when a condensate of 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride and m-phenylenediamine and a condensate of p-phenylenediamine are used together, The dispersion diameter in the polyester can be controlled by the ratio, which is preferable.
[0047]
[Chemical 8]

[0048]
Or
[0049]
[Chemical 9]

[0050]
(N is an integer of 2 or more, preferably an integer of 20 to 50)
This polyetherimide is available from GE Plastics under the trade name “Ultem” (registered trademark).
[0051]
The polyethersulfone used as a thermoplastic resin other than polyester is a polymer having a repeating unit of the following formula in which an aromatic ring is bonded to one sulfonyl group and one or two ether groups, The structural unit may be copolymerized to some extent.
[0052]
[Chemical Formula 10]

[0053]
Embedded image

[0054]
Embedded image

[0055]
The polysulfone used as a thermoplastic resin other than polyester is a polymer having a repeating unit of the following formula, but may contain a functional group such as an alkyl group, and other structural units are copolymerized to some extent. May be.
[0056]
Embedded image

[0057]
In order to control the domain diameter (dispersion diameter), a compatibilizer may be used in combination with the polymer constituting the thermoplastic resin film of the present invention, if necessary. In this case, although the kind of compatibilizer varies depending on the kind of polymer, the addition amount is preferably 0.01 to 10% by weight.
[0058]
When the thermoplastic resin film of the present invention contains a thermoplastic resin other than polyester, the content of the thermoplastic resin other than one kind of polyester in the film layer of the present invention is 1 to 30 in an amount relative to the polymer alloy in the film. It is preferably in the range of wt%. More preferably, it is 5 to 15% by weight. In general, the melt viscosity of the thermoplastic resin of the present invention is greatly different from that of the polyester. Therefore, if the content of the thermoplastic resin is less than 1% by weight, it may be difficult to sufficiently finely disperse with an extruder. The domain of the thermoplastic resin becomes a coarse dispersion, and the domains may be difficult to align. If the content of one kind of thermoplastic resin is more than 30% by weight, the phase separation structure does not become a sea-island structure, but a mutual continuous structure, and domain alignment may not occur.
[0059]
When two or more types of thermoplastic resins are included, the total content of thermoplastic resins other than polyester in the film layer of the present invention is preferably in the range of 1 to 50% by weight. When the content of the thermoplastic resin is less than 1% by weight, it may be difficult to sufficiently finely disperse with an extruder, and when the content of the thermoplastic resin exceeds 50% by weight, stretching May be difficult to manufacture.
[0060]
In the present invention, the time when the thermoplastic resin other than polyester is added to the polyester may be added before the polymerization of the polyester, for example, before the esterification reaction, or after the polymerization. Further, it may be mixed and pelletized before melt extrusion.
[0061]
After pelletizing, once the master pellets made of polyester and thermoplastic resin other than polyester having the same content ratio (for example, the content of thermoplastic resin other than polyester is 40 to 60% by weight) is prepared. Furthermore, when a method of further diluting with polyester and adjusting to a predetermined concentration is used, the dispersibility between polymers is improved, the occurrence of defective dispersion is suppressed, and a more preferable dispersion state is exhibited as the polymer of the present invention. Become.
[0062]
Other methods for adjusting the polymer of the present invention to a more preferable dispersed state include, for example, a method of mixing using a tandem extruder, a method of mixing a thermoplastic resin after being pulverized with a pulverizer, and both A method of mixing by dissolving in a solvent and coprecipitation, a method of mixing one into a solution after dissolving one in a solvent, and the like are also included. Furthermore, two different types of thermoplastic resins are twin screw extruders. Preferably, a method of melt-mixing with a polyester after preparing a thermoplastic resin / thermoplastic resin blend by, for example, volatilizing the solvent after the mixture is melt-mixed using a solution or by mixing as a solution dissolved in a solvent is used. This is not the case.
[0063]
The thermoplastic resin film of the present invention is related to the melt viscosity of the polymer, the shearing force during extrusion, the particle diameter of the inert particles, the polymer domain diameter, the particle concentration of the inert particles, and the thermoplastic resin concentration in the polyester. Although considered to be due to a hydrodynamic effect, there are domains or inert particles having an aligned structure in at least one direction in the plane direction of the film (in the case of a laminated film, the film layer of the present invention) (hereinafter, domains) May be referred to as a polymer domain). By aligning inert particles or polymer domains with directionality, when used as the outermost surface of a film, it is possible to obtain an anisotropic surface in which protrusions are aligned in a line, for example, in magnetic tape. When used as a running surface, it reduces air biting with the guide roll when running at high speeds, reduces lateral displacement of the tape during high speed running, and reduces the force applied in the thickness direction by linear protrusions. By dispersing, it is possible to suppress the transfer of the protrusion on the running surface side to the magnetic surface side due to the tape pack stress in the thickness direction when storing the tape. Further, when used for the film center layer, it is possible to impart the property of being easily torn in the alignment direction without affecting the form of the surface layer in either case of domain or inert particle.
[0064]
In the present invention, “inert particles or domains have an aligned structure in at least one direction in the plane direction” is determined by the following method. 30 points of the surface layer (30 μm □, thickness of about 0.5 μm) of the film are observed with a transmission electron microscope (TEM). Number of particles or thermoplastic resin domains observed in a 30 μm × 1 μm rectangle having a long side in one direction in the plane of the film (N₁) And the number of particles or thermoplastic resin domains (N) observed in a 30 μm × 1 μm rectangle having a long side in the direction perpendicular to the above direction in the film plane₂) Means that 15 or more of 30 points are observed. The central point of the rectangular portion to be observed (30 μm × 1 μm) is the central point of the TEM observation portion (30 μm □).
[0065]
N₁> N₂N₁/ N₂> 1.3
N₂> N₁N₂/ N₁> 1.3
When the thermoplastic resin film of the present invention is used as a magnetic recording medium, the surface roughness Ra of at least one surface is preferably 1 nm to 25 nm, more preferably 5 to 15 nm, and particularly preferably 7 to 12 nm. When Ra is smaller than 1 nm, the friction coefficient with a transport roll or the like is increased in film production, processing steps, etc., which may cause a process trouble. If Ra is larger than 25 nm, transfer to the magnetic surface side may occur when used as a magnetic tape for high-density recording.
[0066]
The surface is not particularly limited, but is preferably a surface on which domains made of thermoplastic resin other than inert particles or polyester are aligned (hereinafter referred to as S surface).
[0067]
Moreover, when using the thermoplastic resin film of this invention for uses other than a magnetic recording medium, when using as a packaging use, for example, Ra is 20 nm-100 nm from a viewpoint of the slipperiness of a manufacture and a process. Is preferred.
[0068]
Moreover, although it does not specifically limit, the centerline surface roughness Ra of the surface (henceforth B surface) on the opposite side to the S surface of the thermoplastic resin film of this invention differs with an appropriate range by a use application. For example, when used as the magnetic recording surface side in magnetic recording medium applications, the thickness is preferably 1 nm to 10 nm, more preferably 2 to 8 nm. Further, for example, when used as a traveling surface side in magnetic recording medium applications, 5 nm to 15 nm is preferable, and 9 nm to 12 nm is more preferable. For example, when used as a packaging application, Ra is preferably 20 nm to 100 nm from the viewpoint of slipperiness in production and processing steps.
[0069]
The total thickness of the film including the thermoplastic resin film of the present invention varies depending on the intended use and is not particularly limited, but is preferably 1 to 500 μm, more preferably 3 from the viewpoint of thin film use and workability. It is in the range of ˜300 μm. Especially, when using for a magnetic tape use, for example, 3-15 micrometers of total thickness are preferable, More preferably, it is 4-8 micrometers.
[0070]
The thermoplastic resin film of the present invention may be used as a single layer film or may be used as at least one film layer in a laminated film depending on the application. As a lamination form in the case of using as a laminated film, for example, a two-layer laminated structure of base layer part / laminated part, a laminated part / base layer part / laminated part, or a three-layer laminated structure of laminated part / laminated part / base layer part, laminated part 4 layer structure of / laminate part / base layer part / laminate part. The base layer here is generally the thickest layer in the film. For example, in a magnetic recording medium application, it is a layer that mainly shares functions such as maintaining strength and dimensional stability. is there. In addition, the laminated portion referred to here is a layer in which the thickness of the film layer is thinner than that of the base layer portion. For example, by making the surface relatively rough, the transportability and winding characteristics of the film can be improved. In a magnetic tape application or the like, it is a layer that functions to obtain good running properties.
[0071]
When the thermoplastic resin film of the present invention is used as a laminated film, which layer in the film the film layer of the present invention is used for depends on the application and purpose. For example, when used for the purpose of reducing friction with a guide pin in a magnetic recording medium such as a magnetic tape, it can be used for a laminated portion of a two-layer laminated film of a base layer portion / a laminated portion. Moreover, when using for the surface design which is smooth and has slidability with a magnetic head, you may use for a base layer part. Moreover, when providing easy-cut property using for a packaging material use etc., it can use for the base layer part of 3 layer laminated | multilayer film of a laminated part / base layer part / laminated part.
[0072]
When the thermoplastic resin film of the present invention is used as a laminated film, the thickness of the laminated part varies depending on the use. For example, in a magnetic recording medium application, from the viewpoint of film strength and surface smoothness, 0.05 μm to 2 μm is preferable, In the case of packaging materials, 1 μm to 5 μm is preferable because of ease of manufacturing.
[0073]
When the thermoplastic resin film of the present invention is used as a laminated film, the resin component constituting the film layer other than the film of the present invention may be a polyester alone, or a polymer alloy comprising a polyester and a thermoplastic resin other than the polyester of the present invention. But it ’s okay. In particular, when polyethylene terephthalate or poly (ethylene-2,6-naphthalenedicarboxylate) is the main resin component, it is preferable that the film-forming property is good and high film strength is obtained.
[0074]
When the thermoplastic resin film of the present invention is used as a laminated film, the film layer other than the film of the present invention may contain inert particles for the purpose of improving the transportability of the film. The particles in that case are not particularly limited, and are inorganic or organic particles having an average particle diameter of about 1 nm to 5 μm, which do not cause a chemical reaction in the polymer of the present invention or adversely affect magnetic recording due to electromagnetic influence. It is. Particle types include titanium oxide, calcium carbonate, kaolin, talc, wet or dry silica, colloidal silica, inorganic particles such as calcium phosphate, barium sulfate, alumina and zirconia, acrylic acids, styrene, silicone, imide, etc. Organic particles, particles precipitated by a catalyst added during the polyester polymerization reaction (so-called internal particles), surfactants, and the like. The average particle size and content of the particles vary greatly depending on the film application and the lamination configuration. In particular, when used for magnetic recording media such as magnetic tape, it is usual to add particles with a small particle size to one film layer and to add particles with a relatively large particle size to the opposite film layer. Is common.
[0075]
The thermoplastic resin film of the present invention is an organic material 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, as long as the effects of the present invention are not impaired. A lubricant or the like may be added.
[0076]
The Young's modulus of the thermoplastic resin film of the present invention varies greatly depending on the intended use of the film.For example, when used as a magnetic recording medium, the sum of the Young's modulus in the longitudinal direction and the Young's modulus in the width direction is the elongation of the magnetic tape. From the viewpoint of deformation and the like, the range is preferably 9 to 25 GPa, more preferably 11 to 22 GPa, and still more preferably 14 to 20 GPa. Further, the Young's modulus in the longitudinal direction is preferably 4.5 GPa or more, more preferably 5.5 GPa or more, and most preferably 6.5 GPa or more, from the viewpoint of per head with the magnetic head. The Young's modulus in the width direction is preferably 4.5 GPa or more, more preferably 5 GPa or more, and most preferably 5.5 GPa or more from the viewpoint of tape edge damage or the like.
[0077]
Although the glass transition start temperature (Tg) of the polymer of the thermoplastic resin film of the present invention is not particularly limited, it is preferably 80 to 150 ° C., more preferably from the viewpoint of the heat resistance and moldability of the film. It is in the range of 90 to 130 ° C, more preferably 100 to 120 ° C.
[0078]
When the polyester of the thermoplastic resin film of the present invention is PET, the thermoplastic resin film of the present invention is 280 ° C. and 1,000 seconds.^-1The melt viscosity in is preferably 300 to 1,000 Pa · s, more preferably 400 to 800 Pa · s. A melt viscosity in the above range is preferred because the inert particles and polymer domains are easily aligned in one direction due to the shear stress during T-die extrusion.
[0079]
Further, when the polyester of the thermoplastic resin film of the present invention is PEN, the thermoplastic resin film of the present invention is 320 ° C. and 1,000 seconds.^-1The melt viscosity in is preferably 400 to 1,500 Pa · s, more preferably 600 to 1,000 Pa · s. A melt viscosity in the above range is preferred because the inert particles and polymer domains are easily aligned in one direction due to the shear stress during T-die extrusion.
[0080]
The use of the thermoplastic resin film of the present invention is not particularly limited, but it can be used for base films for magnetic recording media, condensers, thermal transfer ribbons, thermal stencils, packaging, optical materials, and the like. Among them, when used as the running surface of the magnetic tape base film, the air flow characteristics with the guide pin are improved, the running property is improved, and the transfer to the smooth magnetic surface side can be suppressed. Moreover, as a packaging use, the easy-cut property can be imparted by utilizing the tearing anisotropy.
[0081]
The thermoplastic resin 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.
[0082]
The thermoplastic resin film of the present invention may be subjected to any processing such as heat treatment, molding, surface treatment, laminating, coating, printing, embossing, etching and the like as necessary.
[0083]
Further, by providing a magnetic layer on at least one surface of the thermoplastic resin film of the present invention, it can be used as a magnetic recording medium. In this case, suitable examples of the magnetic layer include a magnetic layer formed by dispersing a ferromagnetic metal thin film or fine powder of ferromagnetic metal in a binder, a magnetic layer coated with a metal oxide, and the like. As the metal used for the ferromagnetic metal thin film, iron, cobalt, nickel, alloys thereof, and the like are preferable. The ferromagnetic metal fine powder used in the magnetic layer in which the ferromagnetic metal fine powder is dispersed in a binder includes ferromagnetic hexagonal ferrite fine powder, powder made of iron, cobalt, nickel and alloys thereof. preferable. The binder is preferably a thermoplastic resin, a thermosetting resin, a reactive resin, or a mixture thereof.
[0084]
In the method for producing the thermoplastic resin film of the present invention, polyester and inert particles, or a polymer alloy of polyester and thermoplastic resin is discharged from a die by melt extrusion using an extruder, and the discharged polymer It is preferable to cool and solidify and form into a sheet. At that time, it is preferable to filter the polymer with a fiber sintered stainless metal filter in order to remove the unmelted material in the polymer alloy.
[0085]
At this time, 1,000 seconds at the extrusion temperature.^-1In the case where the melt viscosity is 200 to 1,000 Pa · s, more preferably 400 to 800 Pa · s, it is preferable that the inert particles and the polymer domain easily form an aligned structure in the film.
[0086]
When discharging from the die, the length of the die land portion of the T die is in the range of 15 to 40 mm, and the shear rate at the die portion is preferably 3 to 200 seconds.^-1More preferably 8 to 100 seconds^-1Controlling in this range is preferable because the inert particles and polymer domains easily form an aligned structure in the film.
[0087]
The thermoplastic resin film of the present invention can be produced by stretching the sheet biaxially in the longitudinal direction and the width direction under specific conditions, and then performing a heat treatment. At this time, the stretching in the longitudinal direction and the width direction may be performed in one step, but may be performed in two or more steps depending on the intended use of the film. Further, when performing re-longitudinal and re-lateral stretching, it is particularly preferable because a high-strength film optimum for a magnetic tape for high-density recording can be easily obtained.
[0088]
Although the total draw ratio in the longitudinal direction when producing the thermoplastic resin film of the present invention is not particularly limited, it is preferably 2.5 to 10 times, more preferably 4.5 to 7 times. When the total stretching ratio in the longitudinal direction is smaller than 2.5 times, the thickness unevenness is deteriorated and the elastic modulus in the longitudinal direction is lowered. For example, when used as a magnetic recording medium, the electromagnetic conversion characteristics may be lowered. is there. When the total stretching ratio in the longitudinal direction is larger than 10 times, film tearing increases and productivity is lowered. Moreover, when the re-longitudinal stretch ratio at the time of performing re-longitudinal stretching is 25% or less of the total longitudinal stretch ratio, it is preferable because film breakage is reduced. When performing re-longitudinal stretching, the stretching ratio of the first longitudinal stretching is preferably 2.5 to 4.0 times, and the re-longitudinal stretching ratio is preferably 1.2 to 2.3 times.
[0089]
Although the total draw ratio in the width direction when producing the thermoplastic resin film of the present invention is not particularly limited, it is preferably 3 to 8 times, more preferably 3.5 to 6 times. When the total stretching ratio in the width direction is smaller than 3 times, the thickness unevenness is deteriorated. For example, when used as a magnetic recording medium, track deviation is likely to occur. When the total draw ratio in the width direction is 6 times or more, productivity may be reduced due to film breakage. Further, when the re-lateral stretching ratio at the time of re-lateral stretching is set to 20% or more of the total transverse stretching ratio, it is preferable because film tearing is reduced. When performing re-lateral stretching, the stretching ratio of the first horizontal stretching is preferably 3.0 to 4.5 times, and the re-longitudinal stretching ratio is preferably 1.2 to 2 times.
[0090]
The stretching temperature in the longitudinal direction when producing the thermoplastic resin film of the present invention is not particularly limited, but from the viewpoint of stretchability and the like, the glass transition temperature Tg of the polymer (the polymer in the base layer in the case of a laminated structure) (Tg + 50 ° C.) is preferable because stretchability is improved. When performing re-longitudinal stretching, the re-longitudinal stretching temperature is preferably (Tg + 30 ° C.) to (Tg + 80 ° C.).
[0091]
The stretching temperature in the width direction when producing the thermoplastic resin film of the present invention is not particularly limited, but from the viewpoint of stretchability, the polymer (in the case of a laminated structure, the polymer in the base layer portion) Tg to (Tg + 50 ° C.) The range of is preferable. When performing re-lateral stretching, the re-lateral stretching temperature is preferably (Tg + 50 ° C.) to (Tg + 150 ° C.).
[0092]
The stretching speed in the longitudinal direction when producing the thermoplastic resin film of the present invention is not particularly limited, but is preferably in the range of 5,000 to 200,000% / min. When performing re-longitudinal stretching, the re-longitudinal stretching speed is A range of 30,000 to 200,000% / min is preferable.
[0093]
The stretching speed in the width direction when producing the thermoplastic resin film of the present invention is not particularly limited, but is preferably in the range of 1,000 to 10,000% / min. Is preferably 1,000 to 20,000% / min.
[0094]
The heat treatment temperature when producing the thermoplastic resin film of the present invention is preferably in the range of 160 ° C to 230 ° C, more preferably 180 ° C to 210 ° C. The heat treatment time for producing the thermoplastic resin film of the present invention is preferably in the range of 0.5 to 10 seconds, more preferably 3 to 8 seconds.
[0095]
The thermoplastic resin film of the present invention may be stretched in the longitudinal direction and the width direction simultaneously using a sequential biaxial stretching method such as stretching in the width direction after stretching in the longitudinal direction or a simultaneous biaxial tenter. The simultaneous biaxial stretching method, and the sequential biaxial stretching method and the simultaneous biaxial stretching method are included.
[0096]
Hereinafter, although the example of the manufacturing method of the thermoplastic resin film of this invention is demonstrated, it is not limited to this. Here, an example of a film using polyethylene terephthalate (PET) as a polyester and polyetherimide (PEI) “Ultem” as a thermoplastic resin is shown.
[0097]
First, a polyester production method will be described using polyethylene terephthalate as an example. The polyethylene terephthalate used in the present invention is produced by any one of the following processes. (1) Using terephthalic acid and ethylene glycol as raw materials, a low molecular weight polyethylene terephthalate or oligomer is obtained by direct esterification reaction, and then a polymer is obtained by polycondensation reaction using antimony trioxide or titanium compound as a catalyst. Process (2) A process in which dimethyl terephthalate and ethylene glycol are used as raw materials, a low molecular weight product is obtained by transesterification, and then a polymer is obtained by polycondensation reaction using antimony trioxide or a titanium compound as a catalyst. Here, the reaction proceeds even without a catalyst, but the transesterification usually proceeds using a compound such as manganese, calcium, magnesium, zinc, lithium, titanium as a catalyst, and the transesterification reaction is carried out. After the completion of the reaction, a phosphorus compound may be added for the purpose of inactivating the catalyst used in the reaction.
[0098]
Moreover, when making the polyester which comprises a film contain an inert particle, the method to which an inert particle is disperse | distributed in the form of a slurry in ethylene glycol in a predetermined ratio, and adding this ethylene glycol at the time of superposition | polymerization is preferable. When adding inert particles, for example, water sol or alcohol sol particles obtained at the time of synthesis of the inert particles are added without drying once, the dispersibility of the particles is good. It is also effective to mix an aqueous slurry of inert particles directly with PET pellets and knead them into PET using a vented biaxial kneading extruder. As a method for adjusting the content of the inert particles, a master pellet of a high concentration of inert particles is prepared by the above method, and this is diluted with PET that does not substantially contain inert particles during film formation. A method for adjusting the content of the active particles is effective.
[0099]
Next, the PET pellets and the PEI pellets are mixed at a predetermined ratio, supplied to a vent type twin-screw kneading extruder heated to 270 to 300 ° C., and melt-extruded. The residence time at this time is preferably 30 to 600 seconds, more preferably 60 to 300 seconds. The obtained chip may be put into a twin screw extruder again and extrusion may be repeated until a preferable dispersion diameter is obtained.
[0100]
The obtained PEI-containing PET pellets are dried under reduced pressure at 180 ° C. for 3 hours or more, and then supplied to an extruder heated to 280 to 320 ° C. under a nitrogen stream or under reduced pressure so that the intrinsic viscosity does not decrease. The film is extruded from a slit-shaped die and cooled on a casting roll to obtain an unstretched film. At this time, 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 altered polymers. Moreover, you may provide a gear pump as needed in order to improve fixed_quantity | feed_rate supply property. When laminating films, a plurality of different polymers are melt laminated using two or more extruders and manifolds or merging blocks.
[0101]
Next, this unstretched film is biaxially stretched and biaxially oriented. Here, a sequential biaxial stretching method in which stretching in the longitudinal direction and then in the width direction is performed first is used. The stretching temperature will be described by taking, for example, a case of having a base layer portion made of polyethylene terephthalate and a laminated portion made of a mixed polymer of polyethylene terephthalate and polyetherimide (mixing weight ratio 9: 1). An unstretched film is heated with a heating roll group of 70 to 120 ° C., for example, and stretched in one or more stages in the longitudinal direction at 2.5 to 10 times (2.5 to 4 times when re-extending in the longitudinal direction). It cools with the cooling roll group of 20-50 degreeC. The stretching speed in the longitudinal direction is preferably in the range of 5,000 to 200,000% / min. Subsequently, stretching in the width direction is performed. As a stretching method in the width direction, for example, a method using a tenter is common. The stretching ratio in the width direction is 3 to 8 times (3 to 4.5 times when relateral stretching is performed), the stretching speed is 1,000 to 10,000% / min, and the temperature is in the range of 80 to 130 ° C. Is preferred. Further, re-longitudinal stretching and re-lateral stretching are performed. As stretching conditions in that case, stretching in the longitudinal direction is preferably a heating roll group at a temperature of 80 to 160 ° C., and a stretching ratio of 1.2 to 2.3 times, and a stretching method in the width direction is preferably a method using a tenter. It is preferable to carry out at a temperature of 130 to 230 ° C. and a draw ratio of 1.2 to 2 times. Subsequently, this stretched film is heat-treated under tension or while relaxing in the width direction. In this case, the heat treatment temperature is preferably 160 to 230 ° C., and the time is preferably in the range of 0.5 to 10 seconds.
[0102]
(Methods for measuring physical properties and methods for evaluating effects)
The characteristic value measurement method and effect evaluation method in the present invention are as follows.
[0103]
(1) Number of inert particles or domains having an aligned structure
Aluminum deposition is performed on the film surface, and the film surface is observed with a differential interference microscope at a magnification of 400 to 1,000 times to determine the direction in which the inert particles or polymer domains are aligned. Moreover, you may discriminate | determine using SEM, TEM, and a phase-contrast microscope as needed.
[0104]
Although not particularly limited, the direction is often the longitudinal direction or the width direction of the film (the direction having the largest value when the refractive index of the film is measured and its vertical direction).
[0105]
Observe the surface layer (thickness: about 0.5 μm, thickness: about 0.5 μm) of the film (in the case of a laminated film, the film layer of the present invention) with a transmission electron microscope (TEM) under a pressure of 100 kV, 40,000 The number of inert particles or polymer domains observed in a rectangular part of 30 μm × 1 μm having a long side in the direction determined above is taken as N.₁And the number of inert particles or polymer domains observed in a rectangular part of 30 μm × 1 μm having a long side in the direction perpendicular to the above direction is N₂And The central point of the rectangular portion to be observed (30 μm × 1 μm) is the central point of the TEM observation portion (30 μm □). If necessary, the number may be counted using image analysis (for example, Image Pro Plus ver. 4.0).
[0106]
(2) 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.
[0107]
Measuring device: Orientec Co., Ltd. film strong elongation automatic measuring device
“Tensilon AMF / RTA-100”
Sample size: width 10mm x test length 100mm
Tensile speed: 200 mm / min
Measurement environment: Temperature 23 ° C, humidity 65% RH
(3) Average particle diameter of inert particles (or domain diameter of polymer domain (dispersion diameter))
The cross section of the film is observed at a magnification of 10,000 times or more using a transmission electron microscope (TEM). The section thickness of TEM is about 100 nm, and the measurement is performed at 100 fields or more at different locations. The average of the equivalent circle equivalent diameters measured was defined as the average particle diameter of the inert particles (or the domain diameter (dispersion diameter) of the polymer domain).
[0108]
When two or more kinds of particles having different particle diameters exist in the film, the number distribution of equivalent circle equivalent diameters is a distribution having two or more peaks, and the average particle diameter is calculated separately for each of them. To do.
[0109]
(4) Content of polyester, thermoplastic resin and inert particles
Dissolve both polyester and thermoplastic resin in a suitable solvent,¹The NMR (nuclear magnetic resonance) spectrum of the H nucleus is measured. A suitable solvent varies depending on the type of polymer, for example, hexafluoroisopropanol (HFIP) / deuterated chloroform is used. In the spectrum obtained, the peak area intensity of the absorption specific to polyester and thermoplastic resin (for example, absorption of aromatic protons of terephthalic acid for PET, absorption of aromatic protons of bisphenol A for PEI) is determined. The molar ratio of polyester to thermoplastic resin is calculated from the ratio and the number of protons. Further, the weight ratio is calculated from the formula amount corresponding to the unit unit of each polymer. The measurement conditions are, for example, the following conditions, but are not limited to this because they differ depending on the type of polymer.
[0110]
Apparatus: BRUKER DRX-500 (Bruker)
Solvent: HFIP / deuterated chloroform
Observation frequency: 499.8 MHz
Standard: TMS (tetramethylsilane) (0 ppm)
Measurement temperature: 30 ° C
Observation width: 10 KHz
Data point: 64K
acquisition time: 4.952 seconds
Pulse delay time: 3.048 seconds
Integration count: 256 times
Moreover, you may perform a composition analysis by microscopic FT-IR method (Fourier transform microinfrared spectroscopy) as needed. In that case, it calculates | requires from ratio of the peak resulting from the carbonyl group of polyester, and the peak resulting from other than that substance. In order to convert the peak height ratio to the weight ratio, a calibration curve is prepared with a sample whose weight ratio is known in advance, and the polyester ratio relative to the total amount of polyester and other substances is determined. The ratio of the thermoplastic resin is determined from this and the inert particle content. Moreover, you may use together an X-ray microanalyzer as needed.
[0111]
In addition, for the content of the inert particles, a solvent that dissolves the polyester and the thermoplastic resin but does not dissolve the inert particles is selected, the polyester and the thermoplastic resin are dissolved, the inert particles are centrifuged, and the weight percentage is obtained. Asked.
[0112]
(5) Lamination thickness
Using a transmission electron microscope (H-600 type manufactured by Hitachi), the film cross section was measured with an ultrathin section method (RuO) at an acceleration voltage of 100 kV.₄Observe by staining). The thickness of each layer is obtained from the observation result of the interface. As the magnification, an appropriate magnification is selected depending on the laminated thickness to be determined, but 10,000 to 100,000 is appropriate.
[0113]
Moreover, it can also measure using a secondary ion mass spectrometer (SIMS). Among inert particles in the film having a depth in the range of 3,000 nm from the surface layer, the concentration ratio between the element caused by the highest concentration of particles (or PEI) and the carbon element of the polyester (M⁺/ C⁺) In the thickness direction from the surface to a depth of 3,000 nm by SIMS. In the surface layer, the element concentration caused by the inert particles is low, and the element concentration caused by the inert particles increases as the distance from the surface increases. In the case of the film of the present invention, the element concentration due to the inert particles once having reached the maximum value starts to decrease again. In this concentration distribution curve, the depth at which the element concentration caused by the inert particles is reduced to ½ of the maximum value is defined as the stack thickness. The conditions are as follows.
[0114]
i) Measuring device
Secondary ion mass spectrometer (SIMS)
West Germany, A-DIDA3000 manufactured by ATOMICA
ii) Measurement conditions
Primary ion species: O₂ ⁺
Primary ion acceleration voltage: 12KV
Primary ion current: 200 nA
Raster area: 400 μm
Analysis area: 30% gate
Measurement vacuum: 5.0 × 10^-9Torr
E-GUN: 0.5KV-3.0A
In addition, when the inert particles contained most in the depth range of 3,000 nm from the surface layer are organic polymer particles, it is difficult to measure by SIMS. Therefore, XPS (X-ray photoelectron spectroscopy), IR ( It is also possible to determine the stack thickness by measuring the same depth profile as described above by infrared spectroscopy.
[0115]
(6) Surface roughness Ra
The center line average roughness Ra was measured using a high precision thin film level difference measuring device ET-10 manufactured by Kosaka Laboratory. The conditions were as follows, and the value was defined as an average value obtained by scanning 20 times in the film width direction. In the case of a laminated film, the surface roughness of the surface on the film layer side of the present application is defined as Ra.₍₁₎, Ra is the surface roughness of the opposite surface₍₂₎And
[0116]
・ Tip tip radius: 0.5μm
-Stylus load: 5mg
・ Measurement length: 1mm
・ Cutoff value: 0.08mm
(7) Melt viscosity
Using a melt indexer, shear rate of 1,000 seconds^-1The viscosity at that time was measured.
[0117]
(8) Glass transition temperature (Tg)
Specific heat was measured with the following equipment and conditions, and determined according to JIS K7121.
[0118]
Apparatus: Temperature modulation DSC manufactured by TA Instrument
Measurement condition:
Heating temperature: 270-570K (RCS cooling method)
Temperature calibration: Melting point of high purity indium and tin
Temperature modulation amplitude: ± 1K
Temperature modulation period: 60 seconds
Temperature rising step: 5K
Sample weight: 5mg
Sample container: Aluminum open container (22 mg)
Reference container: Aluminum open container (18mg)
The glass transition temperature was calculated by the following formula.
[0119]
Glass transition temperature = (extrapolated glass transition start temperature + extrapolated glass transition end temperature) / 2
(9) Shear rate of the base part
Obtained according to the following formula.
[0120]
J = 6Q / wt²
Where J: shear rate (sec^-1)
Q: Flow rate (g / sec)
w: Width of base (cm)
t: Slit width (cm)
(10) Degree of alignment of inert particles or polymer domains (N₁/ N₂)
According to the measurement method of (1) above, 30 points were observed,₁, N₂And the ratio N₁/ N₂Is calculated. At this time, N satisfying the following relationship:₁/ N₂Is 15 points or more out of 30 points, it is determined that the inert particles or polymer domains are aligned in one direction (having an aligned structure) in the film.
[0121]
N₁> N₂N₁/ N₂> 1.3
N₂> N₁N₂/ N₁> 1.3
(11) Transfer resistance of magnetic tape
A film slit to a width of 1 m is transported at a tension of 20 kg / m, and a magnetic paint having the following composition and a non-coated surface are formed on the surface opposite to the side where the domains made of thermoplastic resin other than the inert particles or polyester are aligned. The magnetic coating is applied in multiple layers by an extrusion coater (the upper layer is a magnetic coating, the coating thickness is 0.1 μm, and the thickness of the nonmagnetic lower layer is appropriately changed), magnetically oriented, and dried at a drying temperature of 100 ° C. Next, a back coat having the following composition was applied to the opposite surface (the surface on which the domains made of thermoplastic resin other than inert particles or polyester were aligned), and then a small test calender device (steel / nylon roll, 5 Step) is calendered at a temperature of 85 ° C. and a linear pressure of 200 kg / cm, and then wound up. The original tape was slit into a 1/2 inch width, and a length of 500 m was wound up with a tension of 10 MPa to prepare a pancake. Next, the surface layer (portion 10 m from the outer end of the pancake) and the core (portion 10 m from the end of the pancake core) were sampled from this pancake, and according to the measurement method of (6), the magnetic surface side The surface roughness Ra was measured. When the difference between the surface roughness Ra (core) of the core and the surface roughness Ra (surface layer) of the core, the surface roughness Ra (core) -surface roughness Ra (surface layer) is 3 nm or less, the transfer resistance is good. When it was larger than 3 nm, it was determined that the transfer resistance was poor.
(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
(12) High speed running stability of magnetic tape
Using the tape running tester TBT-300 (manufactured by Yokohama System Laboratory Co., Ltd.), the magnetic tape processed in the above (11) with a position regulating plate at one end in an atmosphere of 60 ° C. and 80% RH Run on a pin (SUS27, 6 mmφ, winding angle 90 °) at a speed of 10 m / sec and a tension of 5 N for 500 m, using a laser dimension measuring instrument, from the initial position of the tape edge opposite the position regulating plate The maximum displacement (μm) was measured. If the maximum displacement is 5 μm or less, it is determined that the high-speed running stability is good.
[0122]
(13) Straight tearability
A strip-shaped film piece of 300 mm in the longitudinal direction of the film and 20 mm in the width direction was cut out, and 10 samples each having a notch of 5 mm in length at the center of one short side of the film piece were prepared. Next, when tearing by hand in the longitudinal direction from the notch, and reaching the short side facing the side where the notch is made, the longitudinal tearing property in the longitudinal direction is good, and when reaching the long side in the middle without reaching the short side The longitudinal linear tearability was regarded as poor. Ten samples were evaluated. If the linear tearability of 5 or more samples was good, the linear tearability was good.
[0123]
【Example】
Based on the following examples, embodiments of the present invention will be described. Here, polyethylene terephthalate is PET, and 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride and a polyetherimide which is a condensate of m-phenylenediamine are m-PEI. Polyetherimide which is a condensate of 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride and p-phenylenediamine is referred to as p-PEI, and polycarbonate is referred to as PC.
[0124]
Example 1
To 194 parts by weight of dimethyl terephthalate and 124 parts by weight of ethylene glycol, 0.1 part by weight of magnesium acetate tetrahydrate was added, and transesterification was performed while distilling methanol at 140 to 230 ° C. Next, 0.05 parts by weight of trimethyl phosphate ethylene glycol solution and 0.05 parts by weight of antimony trioxide were added and stirred for 5 minutes, and then the reaction system was heated from 230 ° C. to 290 ° C. while stirring the low polymer at 30 rpm. While gradually raising the temperature to 0 ° C., the pressure was reduced to 0.1 kPa. The time to reach the final temperature and final pressure was both 60 minutes. When the polymerization reaction is performed for 3 hours and a predetermined stirring torque is reached, the reaction system is purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, discharged into cold water in a strand form, and immediately cut to have an intrinsic viscosity of 0.62. Polyethylene terephthalate (PET) pellets were obtained. The glass transition temperature of the PET pellets was 78 ° C.
[0125]
50% by weight of the obtained polyethylene terephthalate pellets (dried under reduced pressure at 180 ° C. for 3 hours), 25% by weight of General Electric (GE) m-PEI “Ultem 1010”, and GE p-PEI “Ultem” 25% by weight of 5001 ″ is fed to a vented twin-screw kneading extruder heated to 300 ° C., melt-extruded, and 25% by weight of m-PEI and 25% by weight of PET / PEI containing p-PEI. Pellets were made.
[0126]
In an extruder heated to a temperature of 280 ° C., 40 parts by weight of the obtained PET / PEI pellets and 60 parts by weight of polyethylene terephthalate pellets (m-PEI content 10% by weight, p-PEI content 10% by weight) After drying under reduced pressure at 180 ° C. for 3 hours, the mixture was supplied and melt-extruded by a T die (die land length 30 mm). The residence time in melt extrusion at this time is 3 minutes, and the shear rate at the die is 12 sec.^-1Met. While applying an electrostatic charge to a cast drum having a surface temperature of 25 ° C., the sheet was closely adhered and cooled and solidified to produce an unstretched thermoplastic resin film (Tg was 95 ° C.) having a thickness of 150 μm.
[0127]
This unstretched film is stretched 3.0 times at a speed of 20,000% / min and at a temperature of 70 ° C. to 110 ° C. in two stages in the longitudinal direction using a roll type stretching machine, and further in the width direction using a tenter. The film was stretched 3.5 times at a speed of 2,000% / min and a temperature of 115 ° C. Subsequently, the film was re-stretched 1.5 times at a temperature of 80 ° C. to 165 ° C. in a single step in the longitudinal direction with a roll-type stretching machine, then heat treated at a temperature of 205 ° C. for 3 seconds under a constant length, and 5% in the width direction. The biaxially oriented thermoplastic resin film having a thickness of 8 μm was obtained.
[0128]
As shown in Table 1, this biaxially oriented thermoplastic resin film had a Young's modulus in the longitudinal direction of 6 GPa, a Young's modulus in the width direction of 4 GPa, and a surface roughness of 9 nm on both sides. Also, 280 ° C, 1,000 seconds^-1The film has a melt viscosity of 600 Pa · s, N₁/ N₂The value of also satisfied the scope of the present application.
[0129]
Comparative Example 1
PET pellets containing 50 parts by weight of PET pellets (Tg 80 ° C.) substantially free of particles obtained in the same manner as in Example 1 and 2% by weight of crosslinked divinylbenzene particles having an average particle size of 0.1 μm were obtained at 180 ° C. After drying under reduced pressure for 3 hours, the mixture was supplied to an extruder, and an unstretched thermoplastic resin film (Tg was 80 ° C.) having a thickness of 150 μm was prepared in exactly the same manner as in Example 1.
[0130]
This unstretched film was stretched 3.0 times in the longitudinal direction at a temperature of 95 ° C. by a roll stretcher, and further stretched 3.5 times in the width direction at a temperature of 100 ° C. using a tenter. Subsequently, the film was stretched 1.5 times at a temperature of 165 ° C. in a longitudinal direction by a roll-type stretching machine, then subjected to a heat treatment at a temperature of 205 ° C. for 3 seconds under a constant length, and then subjected to a relaxation treatment of 5% in the width direction. A biaxially oriented thermoplastic resin film having a thickness of 8 μm was obtained.
[0131]
As shown in Table 1, this biaxially oriented thermoplastic resin film had a Young's modulus in the longitudinal direction of 7 GPa, a Young's modulus in the width direction of 4 GPa, and a surface roughness of 9 nm on both sides. Also, 280 ° C, 1,000 seconds^-1The melt viscosity of the film at 150 Pa · s is N₁/ N₂The value of did not satisfy the scope of the present application. In addition, as shown in Table 1, the high-speed running stability when processed into a magnetic tape was also inferior to that of Example 1.
[0132]
Example 2
In the same manner as in Example 1, 50% by weight of the obtained PET pellets (Tg 80 ° C.) and 50% by weight of GE's “Ultem” 1010 (Tg 216 ° C.) were heated to 290 ° C. and rotated in the same direction. A PET / PEI blend chip containing 50% by weight of PEI was prepared by feeding to a twin screw extruder.
[0133]
Next, film formation was performed using two extruders.
[0134]
The extruder 1 (for the laminated part) heated to 280 ° C. has an intrinsic viscosity of 0.85 containing 40 parts by weight of the above PET / PEI blend chip and 20% by weight of spherical silica particles having an average particle diameter of 50 nm. Mixed raw material of PET pellets 60 parts by weight (280 ° C., 1000 seconds^-1The melt viscosity was 400 Pa · s) at 180 ° C. for 3 hours under reduced pressure for 3 hours.
[0135]
In the extruder 2 (for the base layer part) heated to 295 ° C., 5 parts by weight of PET pellets having an intrinsic viscosity of 0.61 containing 1% by weight of silica having an average particle diameter of 50 nm, and inherently substantially free of particles A mixed raw material of 95 parts by weight of PET pellets having a viscosity of 0.61 was supplied after drying under reduced pressure at 180 ° C. for 3 hours.
[0136]
These were each filtered in the order of a sand filter and a fiber-sintered stainless metal filter, and then merged in a T-die, and in the same manner as in Example 1, a two-layer laminated unstretched film (laminate thickness ratio: laminate part / base layer part) = 1/5).
[0137]
This unstretched film was stretched simultaneously at a speed of 2,000% / min in the longitudinal and width directions at a temperature of 100 ° C. and 4 times in the longitudinal direction and 4 times in the width direction using a simultaneous biaxial tenter. Subsequently, using a simultaneous biaxial tenter, the film was stretched 1.5 times in the longitudinal direction at a speed of 2,000% / min and at a temperature of 150 ° C., and then heat treated at a temperature of 220 ° C. for 5 seconds under a constant length. A biaxially oriented thermoplastic film having a thickness of about 6 μm was prepared by performing a relaxation treatment of 5% in the direction.
[0138]
The film thickness of each layer was 5 μm for the base layer portion and 1 μm for the laminated portion (film layer of the present invention). The Young's modulus in the longitudinal direction was 7 GPa, and the Young's modulus in the width direction was 5 GPa.
[0139]
As shown in Table 2, this thermoplastic resin film is N₁/ N₂The value of satisfying the scope of the present application. Further, as shown in Table 3, the film was excellent in high-speed running stability and transfer resistance when processed into a magnetic tape.
[0140]
Example 3
The obtained polyethylene terephthalate pellets (dried under reduced pressure at 180 ° C. for 3 hours) were 70% by weight, and the aromatic polycarbonate pellets “Iupilon” (registered trademark) S-2000 (manufactured by Mitsubishi Engineer Plastics: glass transition temperature 150 ° C. ) (Drying under reduced pressure for 3 hours at a temperature of 120 ° C.) 30 wt% blended, fed to a vented twin-screw kneading extruder heated to 280 ° C., melt extruded, and PET containing 30 wt% aromatic polycarbonate / PC pellets were prepared. The resulting pellet was transparent (280 ° C., 1,000 seconds^-1The melt viscosity at 800 Pa · s).
[0141]
Subsequently, film formation was performed using two extruders.
[0142]
In the extruder 1 heated to a temperature of 280 ° C., 30 parts by weight of the obtained PET / PC pellets and 70 parts by weight of polyethylene terephthalate pellets (PC content 9% by weight) were dried under reduced pressure at 180 ° C. for 3 hours. The same raw material as in Example 2 was supplied to the extruder 2. These were each filtered in the order of a sand filter and a fiber-sintered stainless metal filter, and then merged in a T-die, and in the same manner as in Example 1, a two-layer laminated unstretched film (laminate thickness ratio: laminate part / base layer part) = 1/3).
[0143]
This unstretched film is stretched 3.5 times at a speed of 20,000% / min at a temperature of 70 ° C. to 105 ° C. in two stages in the longitudinal direction using a roll-type stretching machine, and further in the width direction using a tenter. The film was stretched 4.2 times at a speed of 2,000% / min and a temperature of 110 ° C., then heat-treated at a temperature of 220 ° C. for 5 seconds under a constant length, and then subjected to a relaxation treatment of 5% in the width direction to a thickness of about 8 μm. A laminated polyester film was prepared.
[0144]
The film thickness of each layer was 6 μm for the base layer portion and 2 μm for the laminated portion (film layer of the present invention). The Young's modulus in the longitudinal direction was 4 GPa, and the Young's modulus in the width direction was 6.2 GPa.
[0145]
As shown in Table 2, this thermoplastic resin film is N₁/ N₂The value of satisfying the scope of the present application. Further, as shown in Table 3, the film was excellent in high-speed running stability and transfer resistance when processed into a magnetic tape.
[0146]
Comparative Example 2
The raw material of the laminated part was changed as shown in Table 2, and the melt viscosity of the raw material of laminated material (280 ° C., 1,000 seconds)^-1) Was set to 250 Pa · s, and a biaxially oriented thermoplastic film having a thickness of about 6 μm was prepared in the same manner as in Example 2.
[0147]
The film thickness of each layer was 5 μm for the base layer part and 1 μm for the laminated part. The Young's modulus in the longitudinal direction was 7 GPa, and the Young's modulus in the width direction was 5 GPa.
[0148]
As shown in Table 2, this thermoplastic resin film is N₁/ N₂The value of did not satisfy the scope of the present application. Moreover, as shown in Table 3, the film was inferior to Examples in terms of transfer resistance when processed into a magnetic tape.
[0149]
Comparative Example 3
By using a PET raw material having an intrinsic viscosity of 0.58 without containing PEI in the laminated part raw material, the melt viscosity (280 ° C., 1,000 seconds)^-1) Was changed to 100 Pa · s, and as shown in Table 2, the particle type and particle content were changed, and the two-layer laminated unstretched film (laminate thickness ratio: laminate portion) was obtained in the same manner as in Example 3. / Base layer part = 1/3).
[0150]
This unstretched film was stretched and heat-treated in the same manner as in Example 3 to produce a laminated polyester film having a thickness of about 8 μm.
[0151]
The film thickness of each layer was 6 μm for the base layer part and 2 μm for the laminated part. The Young's modulus in the longitudinal direction was 4.2 GPa, and the Young's modulus in the width direction was 6.3 GPa.
[0152]
As shown in Table 2, this thermoplastic resin film is N₁/ N₂The value of did not satisfy the scope of the present application. Moreover, as shown in Table 3, the film was inferior to Examples in terms of high-speed running stability and transfer resistance when processed into a magnetic tape.
[0153]
Example 4
The same m-PEI and p-PEI as in Example 1 were dissolved in N-methylpyrrolidone (NMP) at a ratio of 1: 3, then the solvent was evaporated, and m-PEI and p-PEI were in a ratio of 1: 3. PEI pellets containing in proportions were made.
[0154]
40 parts by weight of the PEI pellets and 60% by weight of PET pellets having an intrinsic viscosity of 0.85 obtained in the same manner as in Example 1 were supplied to a vent type twin-screw kneading extruder heated to 300 ° C. and melt extruded. A PET / PEI pellet containing 10% by weight of m-PEI and 30% by weight of p-PEI was prepared.
[0155]
Subsequently, film formation was performed using two extruders.
[0156]
In the extruder 1 (for the base layer part) heated to a temperature of 280 ° C., a mixed raw material (Tg 95 ° C., 280 ° C., 1,000 seconds) of 50 parts by weight of the PET / PEI pellets and 50 parts by weight of the polyethylene terephthalate pellets was used.^-1The melt viscosity at 500 Pa · s was dried after drying at 180 ° C. for 3 hours under reduced pressure, and supplied to the extruder 2 (for laminating part) as shown in Table 2 with 1 ml of crosslinked divinylbenzene having an average particle size of 0.3 μm. A PET raw material having an intrinsic viscosity of 0.60 and containing% by weight was supplied.
[0157]
These were each filtered in the order of a sand filter and a fiber-sintered stainless steel filter, and then merged in a T-die, and in the same manner as in Example 1, a three-layer laminated unstretched film (laminated thickness ratio: laminated portion / base layer portion) / Laminated part = 1/48/1).
[0158]
This unstretched film was stretched three times at a speed of 20,000% / min and at a temperature of 70 ° C. to 115 ° C. in two stages in the longitudinal direction using a roll-type stretching machine, and further, a speed of 2 in the width direction using a tenter. The film was stretched 3 times at a temperature of 110 ° C. at 1,000%, and then heat-treated at a temperature of 240 ° C. for 5 seconds under a constant length to prepare a laminated polyester film having a thickness of about 50 μm.
[0159]
The film thickness of each layer was 48 μm in the base layer part (film layer of the present invention), and 1 μm in each laminated part. The Young's modulus in the longitudinal direction was 4.1 GPa, and the Young's modulus in the width direction was 4.2 GPa.
[0160]
As shown in Table 2, this thermoplastic resin film is N₁/ N₂The value of satisfying the scope of the present application. Further, as shown in Table 4, the film had good linear tearability.
[0161]
Comparative Example 4
As shown in Table 2, as a raw material of the base layer part, a PET raw material having an inherent viscosity of 0.65 substantially containing no particles (Tg 80 ° C., 280 ° C., 1,000 seconds)^-1A three-layer laminated unstretched film (lamination thickness ratio: lamination part / base layer part / lamination part = 1/48/1) was prepared in the same manner as in Example 4 except that the melt viscosity in the film was 150 Pa · s). did.
[0162]
This unstretched film was stretched three times at a speed of 20,000% / min and at a temperature of 70 ° C. to 95 ° C. in two stages in the longitudinal direction using a roll-type stretching machine, and further, a speed of 2 in the width direction using a tenter. The film was stretched 3 times at 1,000% / min at a temperature of 100 ° C., and then heat-treated at a temperature of 240 ° C. for 5 seconds under a constant length to prepare a laminated polyester film having a thickness of about 50 μm.
[0163]
The film thickness of each layer was 48 μm for the base layer portion and 1 μm for the laminated portion. The Young's modulus in the longitudinal direction was 4.5 GPa, and the Young's modulus in the width direction was 4.5 GPa.
[0164]
As shown in Table 2, this thermoplastic resin film is N₁/ N₂The value of did not satisfy the scope of the present application. Moreover, as shown in Table 4, it was a film with poor linear tearability.
[0165]
[Table 1]

[0166]
[Table 2]

[0167]
[Table 3]

[0168]
[Table 4]

[0169]
【The invention's effect】
According to the present invention, by forming a structure in which particles or polymer domains are aligned in a film, a fine streak-like structure is formed on the surface layer, transfer is difficult to occur, and stability when running at high speed is achieved. A high-quality polyester film can be obtained as a base film of a magnetic tape for a magnetic recording apparatus having excellent properties.

Claims (9)

A thermoplastic resin film containing 50% by weight or more of polyester and having a domain having an aligned structure in at least one direction in the plane direction. A thermoplastic resin film containing 50% by weight or more of polyester and having inert particles having an aligned structure in at least one direction in the plane direction. The thermoplastic resin film according to claim 1 or 2, wherein the surface roughness Ra of at least one surface is 1 to 25 nm. The thermoplastic resin film according to any one of claims 1 to 3, comprising at least one thermoplastic resin selected from the group consisting of polycarbonate, polyimide, polysulfone and polyethersulfone. 5. The thermoplastic resin film according to claim 4, wherein the polyester is polyethylene terephthalate and contains 5 to 15 wt% of a polyetherimide represented by the following chemical formula as the thermoplastic resin.

The heat according to any one of claims 1 to 5, wherein the polyester is polyethylene terephthalate and contains 5 to 15% by weight of at least one particle selected from the group consisting of crosslinked polystyrene, silica, alumina and silicone. Plastic resin film. The thermoplastic resin film according to any one of claims 1 to 6, wherein the polyester is polyethylene terephthalate and the melt viscosity at 280 ° C and 1,000 seconds ^-1 is 300 to 1,000 Pa · s. A laminated film having at least one layer of the thermoplastic resin film according to claim 1. A magnetic recording medium comprising a magnetic layer on at least one surface of the thermoplastic resin film according to claim 1 or the laminated film according to claim 8.