JP2004288268A - Polyester film for recording medium, its manufacturing method, and magnetic recording tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film for a recording medium, which can be used for a office-use vapor deposition magnetic tape such as a DVCAM nearly free from dropouts and excellent in durability and to provide a manufacturing method of the polyester film. <P>SOLUTION: In the polyester film for the recording medium wherein a coating film containing fine particles and an organic compound is formed on one side surface of the film, the surface on the coating film side is the surface on which a data recording material thin film is formed, fine surface protrusions on the surface of the coating film have 5 to 60 nm diameter and the surface of the coating film has 3 to 100 million pieces fine surface protrusions/mm<SP>2</SP>, 0.5 to 3.0 nm surface roughness value Ra, ≤1 piece/2m<SP>2</SP>stripe-shaped defects having ≥0.2 μm depth or height and ≥1 m length and ≤1 piece/2m<SP>2</SP>lump-shaped surface adhesions having ≥0.6 μm height. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４３】
（式１〜式６中、Ｒ１〜Ｒ３はそれぞれ独立に、水素、炭素数１〜３０の炭化水素基、アルコキシ基、水酸基、カルボニル基、アセチル基、カルボキシル基もしくはエステル基を、又はアミノ基を有する炭素数１〜３０の炭化水素基を表す。）
【００４４】
上記式１の官能基としては、エトキシド、プロポキシド、イソプロポキシド、ブトキシド、２−エチルヘキソキシド等のアルコキシ基、乳酸、リンゴ酸、酒石酸、クエン酸等のヒドロキシ多価カルボン酸系化合物からなる官能基が挙げられる。また、上記式２の官能基としては、アセチルアセトン等のβ−ジケトン系化合物、アセト酢酸メチル、アセト酢酸エチル等のケトエステル系化合物からなる官能基が挙げられる。また、上記式３の官能基としては、フェノキシ、クレシレイト、サリチル酸等からなる官能基が挙げられる。
【００４５】
また、上記式４の官能基としては、ラクテート、ステアレート等のアシレート基、フタル酸、トリメリット酸、トリメシン酸、ヘミメリット酸、ピロメリット酸、シュウ酸、マロン酸、コハク酸、グルタル酸、アジピン酸、セバシン酸、マレイン酸、フマル酸、シクロヘキサンジカルボン酸またはそれらの無水物等の多価カルボン酸系化合物、エチレンジアミン四酢酸、ニトリロ三プロピオン酸、カルボキシイミノ二酢酸、カルボキシメチルイミノ二プロピオン酸、ジエチレントリアミノ五酢酸、トリエチレンテトラミノ六酢酸、イミノ二酢酸、イミノ二プロピオン酸、ヒドロキシエチルイミノ二酢酸、ヒドロキシエチルイミノ二プロピオン酸、メトキシエチルイミノ二酢酸等の含窒素多価カルボン酸からなる官能基が挙げられる。また、上記式５の官能基としては、アニリン、フェニルアミン、ジフェニルアミン等からなる官能基が挙げられる。
【００４６】
中でも、式１の官能基及び／又は式４の官能基が含まれるチタン化合物触媒がポリマーの熱安定性及び色調の観点から好ましい。
【００４７】
具体的なチタン化合物系の触媒としては、これら式１〜式６の置換基の２種以上を含んでなるチタンジイソプロポキシビスアセチルアセトナートやチタントリエタノールアミネートイソプロポキシド等が挙げられる。また、チタン酸化物系の触媒としては、主たる金属元素がチタン及びケイ素からなる複合酸化物や超微粒子酸化チタンが挙げられる。
【００４８】
これらチタン化合物触媒は、ジカルボン酸又はそのエステル形成性誘導体とジオール又はそのエステル形成性誘導体とから合成されるポリエステルを製造させる重合工程において、以下の（１）〜（３）の反応（全て又は一部の素反応）を促進させるために実質的に寄与する触媒機能を発揮するものである。
（１）ジカルボン酸成分とジオール成分との反応であるエステル化反応、
（２）ジカルボン酸のエステル形成性誘導体成分とジオール成分との反応であるエステル交換反応、
（３）実質的にエステル反応またはエステル交換反応が終了し、得られたポリエチレンテレフタレート低重合体を脱ジオール反応にて高重合度化せしめる重縮合反応、
【００４９】
また、ポリエステル中に所定量のリン化合物を含有させるためには、ポリエステルの製造工程でリン化合物を添加すればよい。このリン化合物としては、リン酸系、亜リン酸系、ホスホン酸系、ホスフィン酸系、ホスフィンオキサイド系、亜ホスホン酸系、亜ホスフィン酸系、ホスフィン系の化合物のいずれでもよく、それらの１種または２種を用いればよい。特にポリエステルの熱安定性及び色調改善の観点から、リン酸系及び／又はホスホン酸系の化合物であることが好ましい。
【００５０】
また、得られるポリマーの色調やポリマーの耐熱性を向上させる目的で、アルカリ金属化合物、アルカリ土類金属化合物、アルミニウム化合物、亜鉛化合物、スズ化合物、マグネシウム化合物、マンガン化合物、コバルト化合物等を添加してもよい。
【００５１】
上記したように、本発明法では、アンチモン化合物の量もゲルマニウム化合物の量も０〜２ｐｐｍと極めて少ない等の特定のポリエステルを用いてフィルムを製造しているので、ポリエステル内で触媒の析出に由来する口金スリット近傍での汚れ物が減少し、フィルム表面におけるスジ状欠点の個数及び塊状付着物をかなり低減させることができる。それでも、スリット近傍での汚れ物を完全になくすことは困難であるので、フィルム表面におけるスジ状欠点の個数を１個／２ｍ^２ 以下、かつ、塊状付着物が１個／２ｍ^２ 以下とするためには、前記した特定のポリエステルを用いることの他に、口金のスリット吐出部においてポリエステルが接するスリット表面の最大高さＲｍａｘを０．６μｍ以下とし、さらに、スリット吐出部表面を１日〜７日毎に１回の頻度で清掃して付着した汚れ物を除去するという手段を採用する。
【００５２】
スリット吐出部の溶融ポリエステルが接するスリット表面の最大高さＲｍａｘ値が０．６μｍを上回ると、フィルム表面でのスジ状欠点の個数を１個／２ｍ^２以下に抑えることが難しくなる。また、スリット吐出部表面の清掃を行わずにフィルム製造を続行する場合や７日を超える清掃間隔で清掃する場合には、口金スリットの溶融ポリエステル接触表面に付着した汚れにより、スジ状欠点の個数を１個／２ｍ^２以下に抑えることが難しくなる。
【００５３】
次に本発明のポリエステルフィルム及び磁気記録テープの製法の一例について説明する。
【００５４】
本発明のポリエステルフィルムは、そのフィルム原料のポリエステルとして、含有粒子を可能な限り除いたポリエステルであって、かつ、触媒残渣由来のチタン化合物をポリエステルに対するチタン原子換算で２〜６ｐｐｍ含有し、リン化合物をポリエステルに対するリン原子換算で０．２〜９ｐｐｍ含有し、アンチモン化合物の存在量がポリエステルに対するアンチモン原子換算で０〜２ｐｐｍであり、ゲルマニウム化合物の存在量がポリエステルに対するゲルマニウム原子換算で０〜２ｐｐｍであり、そのチタン化合物とリン化合物の比率が、原子換算の重量比率でＴｉ／Ｐ＝０．７〜１０であるポリエステルを用いる。このポリエステルを原料にして、乾燥、溶融、成形、二軸延伸、熱固定からなる通常のプラスチックフィルム製造工程でフィルムを製造する。例えば、ポリエステルチップを、溶融押出し、加熱された延伸ロールにより長手方向に延伸した後に、一方向に延伸されたポリエステルフイルムの片側表面Ａに被覆層を設けるための塗液を塗布した後に、乾燥後あるいは乾燥させながら、上記延伸方向と直角の方向に延伸し、必要に応じて更なる延伸を必要な方向に施した後に熱処理を行うことにより製造される。そして、その延伸工程では９０〜１４０℃で、縦、横方向に、２．７〜５．５倍、３．５〜７．０倍に延伸し、１９０〜２２０℃の温度で熱固定する。
【００５５】
本発明のポリエステルフィルムを製造するためには、さらに、口金のスリット吐出部における表面最大高さＲｍａｘを０．６μｍ以下とし、かつ、スリット吐出部汚れ物を１日〜７日毎に１回の頻度で清掃する。
【００５６】
また、フィルムの片側表面Ａにおける被膜形成は、次の操作により行われる。
長手方向に延伸した後の平滑なポリエステルフィルムの片側表面に、水溶性高分子又は水分散性高分子と平均粒径５〜５０ｎｍの微細粒子とを主成分として含有する水系塗液を、固形分塗布濃度３〜１００ｍｇ／ｍ^２となるように塗布する。水溶性高分子又は水分散性高分子としては、ポリビニルアルコール、トラガントゴム、カゼイン、ゼラチン、セルロース誘導体、水溶性ポリエステル、水溶性ポリエステルエーテル共重合体、ポリウレタン、イソフタル酸エステル樹脂、メタクリル酸エステル樹脂等の有極性高分子、これらのブレンド体が使用できるが、これらに限定されない。
【００５７】
この水系塗液中の微細粒子の含有量は、０．５〜１２．０重量％が好ましく、さらには０．６〜１０．０重量％が好ましい。また、その水溶液の固形分塗布濃度は３〜１００ｍｇ／ｍ^２であることが好ましい。固形分塗布濃度が３ｍｇ／ｍ^２を下回ると、微細表面突起の個数が３００万個／ｍｍ^２を、また、表面粗さＲａ値が０．５ｎｍを下回りがちとなる。固形分塗布濃度が１００ｍｇ／ｍ^２ を上回ると、微細表面突起の個数が１億個／ｍｍ^２を、また、表面粗さＲａ値が３．０ｎｍを上回りがちとなる。
【００５８】
なお、共押出し技術の使用により、前記した原料をＡ層用の原料（原料Ａ）とし、積極的により大きな微粒子を含有させたＢ層用の原料（原料Ｂ）を用いてＡ／Ｂ積層フィルムを溶融押出しし製膜してもよいし、Ｂ層を用いなく、前記表面Ａ側と反対の表面Ｂ側に滑剤を含む塗液を塗布しＢ面側に易滑処理をしてもよい。Ｂ層を用い、更に滑剤を含む塗液を塗布しＢ面側の易滑処理をしてもよい。
【００５９】
また、磁性層の耐久性を更に向上させるためには、原料Ａに粒径５０〜１００ｎｍの微細粒子を０．０５重量％以下の量で加えてもよい。その微細粒子としては炭酸カルシウム、シリカ、アルミナ、ポリスチレン等が例示される。
【００６０】
二軸延伸は、例えば逐次二軸延伸法、同時二軸延伸法で行うことができるが、所望するならば熱固定前にさらに縦あるいは横方向あるいは縦と横方向に再度延伸させ機械的強度を高めた、いわゆる強力化タイプとすることもできる。
【００６１】
本発明のポリエステルフィルムは磁気記録媒体のベースフィルムとして、デジタルデータを記録する磁気テープ用途に、特にＤＶＣＡＭ磁気テープ用途に優れた結果を得ることができ、好適である。また、光反応性のＧｅ、Ｓｂ、Ｔｅ等から成る映像データ記録用合金膜が形成され、映像データ等の記録が可能な光記録テープのベースフィルムとしても好適に用いることができる。
【００６２】
本発明の磁気記録テープは、本発明のポリエステルフィルムの被膜表面Ａ上に、真空蒸着により形成される強磁性金属薄膜層を設け、そしてテープ状にしたものであり、使用する金属薄膜としては公知のものを使用でき、特に限定されないが、鉄、コバルト、ニッケル、またはそれらの合金の強磁性体からなるものが好ましい。金属薄膜層の厚さは一般に２０〜３００ｎｍである。
【００６３】
即ち、本発明の磁気記録テープは、本発明のポリエステルフィルムの被膜表面Ａ上に、Ｃｏ等からなる強磁性金属薄膜を、真空蒸着により膜厚み２０〜３００ｎｍ程度で形成し、この金属薄膜上に１０ｎｍ程度の厚みのダイヤモンド状カーボン膜をコーティングし、さらにその上に、潤滑剤を塗布し、他方、片側表面Ｂに、固体微粒子および結合剤からなり必要に応じて各種添加剤を加えた溶液を塗布することによりバックコート層を設け、そして、所定のテープ幅に切断することにより、製造することができる。その固体微粒子、結合剤、添加剤は公知のものを使用でき、特に限定されない。バックコート層の厚さは０．３〜１．５μｍ程度が好ましい。
【００６４】
【実施例】
本実施例で用いた測定法を下記に示す。
【００６５】
（１）フィルム上の微細表面突起の個数
フィルム表面を走査型電子顕微鏡により５万倍の拡大倍率で１０視野以上観察し、突起状に見える突起が１ｍｍ^２あたり何個あるかを測定することにより、フィルムの表面に形成された微細突起の個数を求めた。
（２）フィルム上の微細表面突起の直径
フィルム表面を走査型電子顕微鏡により５万倍の拡大倍率で５視野観察し、各視野より突起状に見える突起をランダムに１０個選び、各突起の最大直径、最小直径を測定し、その平均値を各突起の直径とし、５０個の突起の直径の平均値を求め、フィルムの表面に形成された微細表面突起の直径とした。
【００６６】
（３）フィルムの表面粗さＲａ値、Ｒｚ値
フィルムの表面の表面粗さＲａ値、Ｒｚ値は、原子間力顕微鏡（走査型プローブ顕微鏡）を用いて測定した。即ち、セイコーインスツルメント（株）製の卓上小型プローブ顕微鏡（“Ｎａｎｏｐｉｃｓ” １０００）を用い、ダンピングモードで、フィルムの表面を４μｍ角の範囲で原子間力顕微鏡計測走査を行い、得られる表面のプロファイル曲線よりＪＩＳ・Ｂ０６０１・Ｒａに相当する算術平均粗さよりＲａを、十点平均粗さよりＲｚ値を求めた。面内方向の拡大倍率は１万〜５万倍、高さ方向の拡大倍率は１００万倍程度とした。
【００６７】
（４）深さもしくは高さが０．２μｍ以上で長さが１ｍ以上のスジ状欠点の個数、高さ０．６μｍ以上の塊状表面付着物の個数
直行ニコル下の偏光で、フィルムの幅方向１ｍ、長手方向２ｍの範囲内を観察し、長手方向に直線上に光るスジの存在を調べた。スジが存在する場合、その長さをスケールで測り、１ｍを超えるスジについて、キーエンス（株）製のレーザー顕微鏡（表面形状測定顕微鏡 ＶＦ−７５００）を用いて観測した。フィルムのどちら側の面に存在するか、また、その深さもしくは高さが０．２μｍ以上であるかを、スジに長手方向に対して均等にｎ＝５の測定を行い、その平均値を求める。その平均値で判断して、深さもしくは高さが０．２μｍ以上で長さが１ｍ以上のスジをスジ状欠点として認めた。その個数と測定範囲面積から、２ｍ^２あたりの個数に換算し、スジ状欠点の個数とした。
【００６８】
高さ０．６μｍ以上の塊状表面付着物については、スジの始端部や終端部の近辺に注目して観察する。即ち、スジの始端部や終端部の近辺を、キーエンス（株）製のレーザー顕微鏡（表面形状測定顕微鏡 ＶＦ−７５００）を用いて観測し、高さ０．６μｍ以上の塊状表面付着物が存在するかを調べた。確認した個数と測定範囲面積から、２ｍ^２あたりの個数に換算し、塊状表面付着物の個数とした。
【００６９】
磁気テープから測定する場合、磁気記録した後に、磁性コロイドを磁気テープ表面に塗布し実体顕微鏡（観測倍率：１０倍）により塗布表面を観察することにより行う。塗布表面上の磁気記録が抜けた箇所がスジ状に存在しないか調べる。
スジ状の場合、そのスジの高さまたは深さをキーエンス（株）製のレーザー顕微鏡（表面形状測定顕微鏡 ＶＦ−７５００）を用いて測定し、スジの長さが１ｍあるかを確認する。また、スジの始端部や終端部の近辺に、高さ０．６μｍ以上の塊状表面付着物が存在しないか調べる。それらの個数と測定範囲面積から、２ｍ^２あたりの個数に換算し、スジ状欠点の個数、塊状表面付着物の個数とした。
【００７０】
（５）フィルムを構成するポリエステル内に含まれるチタン化合物、リン化合物、アンチモン化合物、ゲルマニウム化合物の量
蛍光Ｘ線（ＦＬＸ）法により、蛍光Ｘ線元素分析装置（堀場製作所社製、ＭＥＳＡ−５００Ｗ型）を用い、フィルム中のポリエステルに含まれるＴｉ，Ｐ、Ｓｂ、Ｇｅの量を定量した。なお、添加剤や被膜中にそれら元素が含まれない場合にはフィルム全体を試料にして測定すればよい。
（６）ポリエステルの固有粘度ＩＶ
オルソクロロフェノールを溶媒として２５℃で測定した。
【００７１】
（７）口金スリット内部のポリマー吐出部表面における表面最大高さＲｍａｘ値口金スリットを組み立てる前に、市販の可搬型の触針式表面粗さ計（“ホンメルテスター”Ｔ−１０００Ｃ Ｇ型）を用いて、カットオフ値２．５ｍｍ、測定長２５ｍｍで、スリット幅方向に１０箇所測り、各Ｒｍａｘ値の平均値をもって口金スリット内部のポリマー吐出部表面のＲｍａｘ値とした。なお、Ｒｍａｘ値とは、得られる表面のプロファイル曲線よりその最大値とその最小値の差である。測定時の面内方向の拡大倍率は１万〜５万倍、高さ方向の拡大倍率は１００万倍程度とした。
【００７２】
（８）磁気テープ（ＤＶＣＡＭテープ）の特性
市販のＤＶＣＡＭデジタルカムコーダー（ソニー製「ＤＳＲ−３００」）を用いてＤＶＣＡＭ標準カセットテープに、静かな室内風景を１８０分録画した後、再生した。その再生時に画面にあらわれるブロック状のモザイク個数（ドロップアウト（ＤＯ）個数）を数えることによって、ＤＶＣＡＭテープ特性を評価した。
ＤＯ個数は記録後の最初の再生時と、１００回再生（３００時間）後とに測定し、３時間あたりのＤＯ個数で表示した。
【００７３】
次に実施例に基づき、本発明を説明する。
【００７４】
［実施例１］
チタン化合物触媒によるポリエチレンテレフタレートの製造：
高純度テレフタル酸（三井化学（株）製）１００ｋｇとエチレングリコール（日本触媒（株）製）４５ｋｇのスラリーを、予めビス（ヒドロキシエチル）テレフタレート約１２３ｋｇが仕込まれ、温度２５０℃、圧力１．２×１０^５Ｐａに保持されたエステル化反応槽に４時間かけて順次供給し、供給終了後もさらに１時間かけてエステル化反応を行い、得られたエステル化反応生成物１２３ｋｇを重縮合槽に移送した。
【００７５】
引き続いて、エステル化反応生成物が移送された重縮合反応槽に、酢酸マグネシウムのエチレングリコール溶液を、得られるポリマーに対してマグネシウム原子換算で３０ｐｐｍとなるように加えた。更に５分間撹拌した後、クエン酸キレートチタン化合物の２重量％エチレングリコール溶液を、得られるポリマーに対してチタン原子換算で５ｐｐｍとなるように添加し、５分後、ジエチルホスホノ酢酸エチルの１０重量％エチレングリコール溶液を、得られるポリマーに対してリン原子換算で５ｐｐｍとなるように添加し、その後、低重合体を３０ｒｐｍで攪拌しながら、反応系を２５０℃から２８５℃まで徐々に昇温するとともに、圧力を４０Ｐａ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分とした。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重縮合反応を停止し、冷水にストランド状に吐出、直ちにカッティングしてポリマーのペレットとした。なお、減圧開始から所定の撹拌トルク到達までの時間は３時間であった。
【００７６】
得られたポリマーのＩＶは０．６６、ポリマーの融点は２５９℃、溶液ヘイズは０．７％であった。また、ポリマーから測定したチタン触媒由来のチタン原子の含有量は５ｐｐｍ、リン原子の含有量は５ｐｐｍであり、Ｔｉ／Ｐ＝１であり、アンチモン原子の含有量もゲルマニウム原子の含有量も０ｐｐｍであることを確認した。
【００７７】
なお、上記の重合工程において触媒として添加したクエン酸キレートチタン化合物は、次の方法で合成した生成物を用いた。
【００７８】
撹拌機、凝縮器及び温度計を備えた３Ｌのフラスコ中に温水（３７１ｇ）にクエン酸・一水和物（５３２ｇ、２．５２モル）を溶解させた。この撹拌されている溶液に滴下漏斗からチタンテトライソプロポキシド（２８８ｇ、１．００モル）をゆっくり加えた。この混合物を１時間加熱、還流させて曇った溶液を生成させ、これよりイソプロパノール／水混合物を真空下で蒸留した。その生成物を７０℃より低い温度まで冷却し、そしてその撹拌されている溶液にＮａＯＨ（３８０ｇ、３．０４モル）の３２重量％水溶液を滴下漏斗によりゆっくり加えた。得られた生成物をろ過し、次いでエチレングリコール（５０４ｇ、８０モル）と混合し、そして真空下で加熱してイソプロパノール／水を除去したところ、わずかに曇った淡黄色のクエン酸キレートチタン化合物（Ｔｉ含有量３．８５重量％）が得られた。
【００７９】
上記方法により重合して得られ、実質的に不活性粒子を含有しないポリエチレンテレフタレートに平均粒径６０ｎｍのシリカを０．０３重量％含有させた原料Ａと、同一のポリエチレンテレフタレートに平均粒径１９０ｎｍのケイ酸アルミニウムを０．１５重量％含有させた原料Ｂとを、各々溶融し、厚み比５：１の割合で口金のスリットからシート状に吐出し、冷却ドラムに密着させて冷却し、ロール延伸法で１１０℃で３．０倍に縦延伸した。
【００８０】
その口金スリットからのポリエステル吐出の際、口金のスリット内部の表面最大高さＲｍａｘは、原料Ａ側も原料Ｂ側も、ともに０．３μｍとした。また口金のスリット内部の、ポリマー吐出部分は７日に１回の頻度で、原料Ａ側も原料Ｂ側もともに清掃して、付着した汚れ物を除去した。その清掃には銅からなる平滑な平板を用いた。
【００８１】
縦延伸の後の工程で、原料Ａ側の表面Ａの外側、原料Ｂ側の表面Ｂの外側に、下記組成の水溶液を２５℃の温度に保ち、０．８μｍのろ過精度を持つフィルターでろ過した後、固形分塗布量４０ｍｇ／ｍ^２ 、５０ｍｇ／ｍ^２ となるように、それぞれ塗布した。
【００８２】
Ａ面外側への塗布水溶液：

【００８３】
Ｂ面外側への塗布水溶液：

【００８４】
その後、ステンターにて横方向に１０２℃で４．２倍に延伸し、２１５℃で熱処理し中間スプールに巻き、スリッターで小幅にスリットし、円筒コアーにロール状に巻取り、厚さ６．３μｍのポリエステルフィルムとした。
このポリエステルフィルムの表面Ａ上に真空蒸着によりコバルト−酸素薄膜を１５０ｎｍの膜厚で形成した。次にコバルト−酸素薄膜層上に、スパッタリング法によりダイヤモンド状カーボン膜を１０ｎｍの厚さで形成させ、フッ素含有脂肪酸エステル系潤滑剤を３ｎｍの厚さで塗布した。続いて表面Ｂ上に、カーボンブラック、ポリウレタン、シリコーンからなるバックコート層を５００ｎｍの厚さで設け、スリッターにより幅６．３５ｍｍにスリットしリールに３１１ｍの長さ巻き取り磁気テープ（ＤＶＣＡＭ用標準テープ）を作製した。
【００８５】
得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００８６】
［実施例２］
実施例１のベースフィルム製造において、ポリエチレンテレフタレートをポリエチレン−２，６−ナフタレートに変更し、原料Ａ、Ｂ内のシリカ、ケイ酸アルミニウムの含有量を０．０７５重量％、０．４５重量％と変更し、縦延伸温度、倍率を１３５℃で５．０倍と変更し、Ａ面、Ｂ面外側塗布の固形分塗布量を６０ｍｇ／ｍ^２、１００ｍｇ／ｍ^２と変更し、横延伸温度、倍率を１３５℃、６．５倍と変更し、２００℃で熱処理に変更し、その他は実施例１と同様にして、厚さ４．７μｍのポリエステルフィルムを作製した。得られたポリエステルフィルムから、実施例１と同様にして幅６．３５ｍｍ、長さ４１７ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は１０ｎｍ、１６０ｎｍであった。
【００８７】
［実施例３］
実施例１のベースフィルム製造において、原料Ａ中の平均粒径６０ｎｍのシリカを用いず、Ａ面側塗液中の極微細シリカの濃度を０．０８重量％としたこと以外は実施例１と同様にしてて厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００８８】
［比較例１］
実施例１のベースフィルム製造において、Ａ面外側への水溶液塗布時の固形分塗布量を２ｍｇ／ｍ^２と変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００８９】
［比較例２］
実施例１のベースフィルム製造において、Ａ面外側への塗布水溶液中の極微細シリカの濃度を０．０９重量％、その水溶液塗布時の固形分濃度を１２０ｍｇ／ｍ^２と変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００９０】
［比較例３］
実施例１のベースフィルム製造において、Ａ面外側への塗布水溶液中の極微細シリカの粒径を４ｎｍ、その水溶液塗布時の固形分濃度を１０ｍｇ／ｍ^２と変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００９１】
［比較例４］
実施例１のベースフィルム製造において、Ａ面外側への塗布水溶液中の極微細シリカの粒径を７０ｎｍ、シリカ添加濃度を０．０８重量％と変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００９２】
［比較例５］
実施例１で得られたチタン化合物触媒によるポリエチレンテレフタレートに、従来の一般的なポリエチレンテレフタレート（アンチモン触媒によるもの、ゲルマニウム触媒によるもの）とを混合したポリマー原料を用いた。なお、この混合ポリマー原料中の元素含有量は表１に示すとおりであった。
【００９３】
アンチモン触媒によるポリエチレンテレフタレート： ポリエチレンテレフタレート重合工程において添加する触媒として、通常のアンチモン系触媒を用い、通常の方法で重合して、ＩＶが０．６６のポリエチレンテレフタレート（ポリエステル中の元素含有利用は、チタンが０ｐｐｍ、リンが１０ｐｐｍ、アンチモンが８０ｐｐｍ、ゲルマニウムが０ｐｐｍ）を製造した。
【００９４】
ゲルマニウム触媒によるポリエチレンテレフタレート： ポリエチレンテレフタレート重合工程において添加する触媒として、通常のゲルマニウム系触媒を用い、通常の方法で重合して、ＩＶが０．６６のポリエチレンテレフタレート（ポリエステル中の元素含有利用は、チタンが０ｐｐｍ、リンが１０ｐｐｍ、アンチモンが０ｐｐｍ、ゲルマニウムが４０ｐｐｍ）を製造した。
【００９５】
実施例１のベースフィルム製造において、フィルム製造用ポリエステル原料を上記した混合ポリマー原料に変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００９６】
［比較例６］
実施例１のポリエステル製造において、重合触媒として用いたクエン酸キレートチタン化合物の添加量を、得られるポリマーに対するチタン原子換算量が１ｐｐｍとなるように変更し、さらに、ジエチルホスホノ酢酸エチルの１０重量％エチレングリコール溶液の添加量を、得られるポリマーに対するリン原子換算量が１ｐｐｍとなるように変更し、それ以外は実施例１と同様にして重合を行い、表１に示す元素含有量のポリエステルを製造した。
【００９７】
得られたポリエステルを用い、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【００９８】
［比較例７］
実施例１のポリエステル製造において、重合触媒として用いたクエン酸キレートチタン化合物の添加量を、得られるポリマーに対するチタン原子換算量が１０ｐｐｍとなるように変更し、さらに、ジエチルホスホノ酢酸エチルの１０重量％エチレングリコール溶液の添加量を、得られるポリマーに対するリン原子換算量が６ｐｐｍとなるように変更し、それ以外は実施例１と同様にして重合を行い、表１に示す元素含有量のポリエステルを製造した。
【００９９】
得られたポリエステルを用い、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１００】
［比較例８］
実施例１のポリエステル製造において、ジエチルホスホノ酢酸エチルの１０重量％エチレングリコール溶液の添加量を、得られるポリマーに対するリン原子換算量が０．１ｐｐｍとなるように変更し、それ以外は実施例１と同様にして重合を行い、表１に示す元素含有量のポリエステルを製造した。
【０１０１】
得られたポリエステルを用い、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１０２】
［比較例９］
実施例１のポリエステル製造において、ジエチルホスホノ酢酸エチルの１０重量％エチレングリコール溶液の添加量を、得られるポリマーに対するリン原子換算量が１２ｐｐｍとなるように変更し、それ以外は実施例１と同様にして重合を行い、表１に示す元素含有量のポリエステルを製造した。
【０１０３】
得られたポリエステルを用い、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１０４】
［比較例１０］
実施例１のベースフィルム製造において、ポリエステル原料を、比較例５で製造した、アンチモン触媒により重合されたポリエチレンテレフタレートに変更し、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１０５】
［比較例１１］
実施例１のベースフィルム製造において、ポリエステル原料を、比較例５で製造した、ゲルマニウム触媒により重合されたポリエチレンテレフタレートに変更し、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１０６】
［比較例１２］
実施例１のポリエステル製造において、重合触媒として用いたクエン酸キレートチタン化合物の添加量を、得られるポリマーに対するチタン原子換算量が３ｐｐｍとなるように変更し、さらに、ジエチルホスホノ酢酸エチルの１０重量％エチレングリコール溶液の添加量を、得られるポリマーに対するリン原子換算量が８ｐｐｍとなるように変更し、それ以外は実施例１と同様にして重合を行い、表１に示す元素含有量のポリエステルを製造した。
【０１０７】
得られたポリエステルを用い、その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１０８】
［比較例１３］
実施例１のベースフィルム製造において、口金として、スリット吐出部における内部の表面最大高さＲｍａｘが、原料Ａ側も原料Ｂ側も、ともに０．８μｍである口金に変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１０９】
［比較例１４］
実施例１のベースフィルム製造において、口金のスリット内部のポリマー吐出部の清掃の頻度を、１４日に１回に変更した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１１０】
［比較例１５］
実施例１のベースフィルム製造において、口金のスリット内部のポリマー吐出部の清掃を行わずにフィルム製造を続行した。その他は実施例１と同様にして厚さ６．３μｍのポリエステルフィルムを作製し、さらに、幅６．３５ｍｍ、長さ３１１ｍの磁気テープを作製した。得られたポリエステルフィルム及び磁気テープの特性を表１に示す。なお、ポリエステルフィルムのＢ面のＲａ値、Ｒｚ値は８ｎｍ、１５０ｎｍであった。
【０１１１】
【表１】

【０１１２】
【発明の効果】
本発明の記録媒体用ポリエステルフィルムを用いると、ＤＶＣＡＭ等の業務用磁気テープを製造した場合でも、ドロップアウトが極めて少なく、耐久性に優れた蒸着型磁気テープとすることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is intended to improve the image quality of a ferromagnetic metal thin film type magnetic recording medium for recording digital data, such as a polyester film for a recording medium, particularly for a digital video cassette tape and a data storage tape, over a long period of time, and to reduce the error rate. And a method for producing the same.
[0002]
[Prior art]
The digital video tape for home use put into practical use in 1995 is made by coating a metal magnetic thin film of Co on one surface of a base film having a thickness of 6 to 7 μm by vacuum evaporation and coating the surface with a diamond-like carbon film. In the case of a camera-integrated video using a DV mini-cassette, the basic specification (SD specification) has a recording time of one hour.
[0003]
This digital video cassette (DVC) is the world's first digital video cassette for home use, comprising: a. A large amount of information can be recorded despite its small body. B. Since the signal does not deteriorate, the image / sound quality does not deteriorate even after many years, c. Enjoys high image quality and high sound quality because it is not affected by noise. D. It has the advantage that the image does not deteriorate even after repeated dubbing, and is highly evaluated in the market.
[0004]
Based on this home DV format, using a vapor-deposited digital video tape, the tape running speed was increased by 1.5 times, and the recording track width was widened from 10 μm to 15 μm of DV, which was required for business use. In 1996, a DVCAM format having the same tape width (1/4 inch) realizing high image quality and high reliability was developed. The DVCAM format is a professional VTR that achieves high image quality, high sound quality, small size and light weight, and has excellent dubbing characteristics and high quality editing performance, and is excellent for business use. It is suitable for companies, productions, cable TV and video journalists. The evaluation has become extremely high.
[0005]
The base film of these digital video tapes includes
(1) Consisting of a polyester film, a polymer blend adhered to at least one surface of the film and a discontinuous film mainly composed of fine particles having a particle size of 50 to 500 °, wherein the discontinuous film is formed of a water-soluble polyester copolymer. A polyester film containing coalesced and having fine projections formed on a discontinuous film by fine particles (for example, see Patent Document 1);
(2) a composite film in which a layer A made of a thermoplastic resin and a layer B made of a thermoplastic resin containing fine particles are laminated (for example, see Patent Document 2);
Etc. have been used.
[0006]
However, in such a base film, foreign matter is present in the polyester used for the film production, the film surface is damaged during the film forming process, and surface defects are caused by surface contaminants attached during the film forming process. And the magnetic tape manufactured from the base film tends to increase dropout (DO).
[0007]
In order to provide a polyester film for a magnetic recording medium capable of stably producing a DVC tape with little dropout, in Patent Document 3, fine surface projections having a height of 10 to 50 nm are formed on one surface A of one side of a polyester film. 3 million to 90 million pieces / mm ^{2 are} provided, and surface protrusions having a height of 50 to 120 nm existing on one surface A are 40,000 pieces / mm ² or less, and surface defects having a height of 120 nm or more are 400 pieces / 100 cm ² or less. Has been proposed.
[0008]
[Patent Document 1] JP-B-63-57238 [Patent Document 2] JP-B 1-226338 [Patent Document 3] JP-A-2000-25105 [0009]
[Problems to be solved by the invention]
However, when a magnetic tape manufactured from such a base film is used as a DVC tape, the dropout (DO) is reduced and the number of DOs per minute can be reduced to almost zero. In such a case, it was possible to record for 3 hours with a standard tape, but about 3 hours of recording tended to generate about 10 DOs. When used for business purposes, it is desirable that no DO be generated over the entire length of the magnetic tape, and there is an increasing demand for reducing the number of DOs to two or less, preferably zero, in three hours.
[0010]
Therefore, an object of the present invention is to provide a polyester film for a recording medium suitable for producing a DVCAM vapor-deposited magnetic tape with a small dropout, and a method for producing the same.
[0011]
[Means for Solving the Problems]
The present invention for achieving the object is as follows. That is,
1. A polyester film for a recording medium in which a film containing fine particles and an organic compound is formed on one surface of a polyester film, wherein the surface on the film side is a surface on which a data recording material thin film is formed, The diameter of the fine surface protrusions on the surface of 5 to 60 nm, the number of the fine surface protrusions is 3,000,000 to 100 million / mm ² , the surface roughness Ra value is 0.5 to 3.0 nm, and the depth or height is 0. For recording media in which the number of streak-like defects having a length of ² μm or more and 1 m or more is 1/2 m ² or less, and the number of bulk surface deposits having a height of 0.6 μm or more is 1 1/2 m ² or less. Polyester film,
2. The polyester contains 2 to 6 ppm of a titanium compound in terms of titanium atoms with respect to the polyester, the amount of the antimony compound is 0 to 2 ppm in terms of antimony atoms with respect to the polyester, and the amount of the germanium compound is 0 to 2 ppm in terms of germanium atoms with respect to the polyester. The recording medium-use polyester film according to the above 1,
3. The polyester further contains a phosphorus compound in an amount of 0.2 to 9 ppm in terms of phosphorus atoms relative to the polyester, and the ratio of the titanium compound to the phosphorus compound is 0.7 to 10 in terms of an atomic weight ratio (Ti / P). The polyester film for a recording medium according to 2,
[0012]
4. The polyester film for a recording medium according to any one of the above 1 to 3, wherein the polyester is polyethylene terephthalate or polyethylene-2,6-naphthalate,
5. The polyester film for a recording medium according to any one of the above 1 to 4, which is used for a magnetic tape of a digital recording system,
6. An aqueous coating liquid containing a water-soluble polymer or a water-dispersible polymer and fine particles as main components on one side surface of the polyester film after the molten polyester is discharged into a sheet from a slit of a die to form a sheet. A method for producing a polyester film for a recording medium according to any one of the above 1 to 5 by forming a coating by applying and drying, and biaxially stretching, wherein the polyester to be melted is titanium. The compound contains 2 to 6 ppm in terms of titanium atoms relative to the polyester; the phosphorus compound contains 0.2 to 9 ppm in terms of phosphorus atoms relative to the polyester; the amount of the antimony compound is 0 to 2 ppm in terms of antimony atom relative to the polyester; Is 0 to 2 ppm in terms of germanium atoms with respect to polyester, A polyester in which the ratio of a titanium compound to a phosphorus compound is 0.7 to 10 in terms of an atomic weight ratio (Ti / P), and the maximum surface height Rmax at the slit discharge portion of the die is 0.6 μm or less; And a method for producing a polyester film for a recording medium, wherein the surface of the slit discharge section is cleaned once every 1 to 7 days.
7. A magnetic recording tape comprising a ferromagnetic metal thin film layer provided on the surface of the polyester film according to any one of the above 1 to 5,
It is assumed that.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The polyester in the present invention may be any polyester that forms a high-strength film depending on the molecular orientation, but polyethylene terephthalate and polyethylene-2,6-naphthalate are preferred. That is, polyethylene terephthalate or polyethylene-2,6-naphthalate in which 80% or more of the constituent components are ethylene terephthalate or ethylene naphthalate is preferred. Examples of the polyester copolymer component other than ethylene terephthalate and ethylene naphthalate include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylylene glycol, and 1,4-cyclohexanedimethanol, adipic acid, Examples include dicarboxylic acid components such as sebacic acid, phthalic acid, isophthalic acid and 5-sodium sulfoisophthalic acid, polyfunctional dicarboxylic acid components such as trimellitic acid and pyromellitic acid, and p-oxyethoxybenzoic acid.
[0014]
Further, the above-mentioned polyester is mixed with at least one of an alkali metal salt derivative of a sulfonic acid which is not reactive with the polyester and a polyalkylene glycol which is substantially insoluble in the polyester so as not to exceed 5% by weight. May be.
[0015]
On one surface A of the polyester film of the present invention, a coating containing fine particles and an organic compound is formed, and fine surface projections due to the fine particles are present on the surface of the coating, the diameter of which is 5 to 60 nm, and the number is from 3 to 100 million units / mm ^2, is preferably from 5,000,000 to 80,000,000 pieces / mm ^2, the surface roughness Ra value is 0.5 to 3.0. Further, the number of streak-like defects having a depth or height of 0.2 μm or more and a length of 1 m or more present on the surface of the coating film is 1/2 m ² or less, more preferably 1/20 m ² , and The number of bulk surface deposits having a thickness of 0.6 μm or more is 1 piece / 2 m ² or less.
[0016]
The fine surface projections on the surface of the film can be formed by providing a film layer containing fine particles in an organic compound on the polyester surface. The particle size of the fine particles is generally about 5 to 50 nm. The particle types include polyacrylic acid, polystyrene, polyethylene, polyester, polyacrylate, polymethyl methacrylate, polyepoxy resin, polyvinyl acetate, acryl-styrene copolymer, acrylic copolymer, and various denatured polymers. Particles of organic compounds such as acrylic resin, styrene-butadiene copolymer, various modified styrene-butadiene copolymers, and particles coated with an organic polymer using inorganic particles such as silica, alumina and calcium carbonate as cores are used. Can, but is not limited to. The organic compound is preferably a self-crosslinkable one whose terminal group is modified with an epoxy, amine, carboxylic acid, hydroxyl group or the like. Note that inorganic particles such as silica and alumina may be used as the fine particles.
[0017]
Organic compounds used in the coating layer include polyvinyl alcohol, tragacanth rubber, casein, gelatin, cellulose derivatives, water-soluble polyester, polyurethane, acrylic resin, acrylic-polyester resin, isophthalic ester resin, and methacrylic ester resin. Polymers Blends of these can be used, but are not limited thereto.
[0018]
Due to the fine surface projections on the coating surface, the wear of the ferromagnetic metal thin film layer formed by vacuum deposition on the coating surface by the magnetic head during recording / reproduction is reduced. If the diameter of the fine surface projections is smaller than 5 nm, or if the number thereof is smaller than 3 million / mm ² , the surface of the magnetic layer of the magnetic tape is too smooth, and the ferromagnetic metal thin film layer becomes too smooth. This is not suitable because the running durability with the magnetic head decreases. If the diameter of the fine surface projections is larger than 60 nm, or if the number thereof is more than 100 million / mm ² , the magnetic layer surface of the magnetic tape is too rough and the dropout of the magnetic tape tends to increase, which is not suitable. .
[0019]
In addition, the Ra value of the coating surface is set so that the ferromagnetic metal thin film formed on the surface by vacuum evaporation minimizes the abrasion received by the magnetic head during recording / reproduction and keeps the output characteristics of the magnetic tape good. It is 0.5 to 3.0 nm, preferably 1.0 to 2.8 nm. If the Ra value is less than 0.5 nm, the ferromagnetic metal thin film layer formed by vacuum evaporation on the surface of the coating film is too smooth, and the recording tape in the video camera contacts with the magnetic head during recording and playback to cause the magnetic tape to run. The ferromagnetic metal thin film is easily worn. If the Ra value exceeds 5 nm, the ferromagnetic metal thin film layer is too rough, and the output characteristics of the magnetic tape are likely to deteriorate.
[0020]
The diameter of the above-mentioned fine surface projections can be adjusted by adjusting the type of fine particles in the coating, the average particle diameter, the transverse stretching temperature, and the like. The number of the fine surface protrusions and the surface roughness Ra value can be adjusted by adjusting the type, average particle size, and solid content application concentration of the fine particles.
[0021]
Further, in the polyester film of the present invention, the number of streak-like defects having a depth or height of 0.2 μm or more and a length of 1 m or more (hereinafter, simply referred to as “streak-like defects”) is 1/2 m ^{2 on} the coating surface. Or less, and the number of massive surface deposits having a height of 0.6 μm or more (hereinafter, also simply referred to as massive deposits) is 1/2 m ² or less. If the streak-like defects are present on the film surface of the film more than the above, in the magnetic tape manufactured from this film, a spacing loss easily occurs between the magnetic tape magnetic layer surface and the magnetic head, and the reproduction output of the magnetic tape is increased. And the occurrence of dropouts increases. Also, if there are many streak-like defects, the stiffness of the magnetic tape tends to decrease, and in the magnetic tape with the reduced stiffness, a spacing loss easily occurs between the surface of the magnetic layer and the magnetic head. This causes a decrease in output and an increase in occurrence of dropout of the DVCAM magnetic tape. Therefore, it is most desirable number of striped defects in the coating surface of the film is nil, for the achievement of the objectives of the present invention, one / 2m ² or less, more preferably 1/20 m ² or less levels And
[0022]
Further, even when there is a lump surface adhering material having a height of 0.6 μm or more on the surface of the film, a spacing loss easily occurs between the magnetic tape magnetic layer surface and the magnetic head, and the reproduction output of the magnetic tape is reduced. In addition, the dropout of the DVCAM magnetic tape tends to increase. Therefore, it is most desirable that the number of mass surface deposit is none, to achieve the objectives of the present invention, one / 2m ² or less, and more preferably at levels of 1/20 m ² or less.
[0023]
Thus, by suppressing the number of streak-like defects and lumps on the coating surface of the film to the above-mentioned level, the dropout (DO) of the DVCAM tape manufactured using this film as a base film can be reduced to a practically sufficient level. Can be reduced to
[0024]
In order to keep the number of these streak-like defects and the number of massive deposits respectively at the above-mentioned levels, it is effective to reduce the amount of foreign substances derived from the catalyst during the polymerization of the polyester, and for that purpose, configure the film In the polyester, the titanium compound is contained in an amount of 2 to 6 ppm in terms of titanium atoms with respect to the polyester, the amount of the antimony compound is 0 to 2 ppm in terms of antimony atoms with respect to the polyester, and the amount of the germanium compound is 0 in terms of germanium atom with respect to the polyester. Preferably it is 2 ppm. Further, the phosphorus compound is contained in an amount of 0.2 to 9 ppm in terms of phosphorus atoms with respect to the polyester, and the ratio of the titanium compound to the phosphorus compound is preferably 0.7 to 10 in terms of the atomic weight ratio (Ti / P). .
[0025]
As described above, when the content of antimony and germanium in the polyester is zero or extremely small, and the content of titanium or phosphorus in a specific range is included, in the melt extrusion process in the film manufacturing process, the antimony from the polyester is used. Since precipitation of heavy metals such as metals and germanium metals can be prevented, the number of heavy metal foreign matters adhering to the polyester film surface can be reduced.
[0026]
This polyester is polymerized using a titanium compound catalyst as a catalyst at the time of polymerization, and the amount of the titanium compound derived from the catalyst residue is preferably 2 to 6 ppm in terms of titanium atoms based on the polyester. In general, it is preferable that the amount of the titanium compound contained as the catalyst residue is as small as possible.However, in order to exert the catalytic effect of the titanium compound catalyst, a certain amount or more of the catalyst is required, so there is a limit to reducing the amount. . That is, if the content is less than 2 ppm in terms of titanium atom relative to the polyester, the time required for the polymerization of the polyester becomes too long, the polyester is thermally degraded, and a thermally degraded product is easily generated in the polyester, and the Ra value exceeds 3.0 nm. It is not preferable because it easily turns. Conversely, if the amount of the titanium compound in the catalyst residue exceeds 6 ppm in terms of titanium atoms, foreign matter derived from the catalyst is likely to precipitate in the polyester, and the deposit adheres to the surface of the die slit when discharged from the die slit. The sheet is undesirably soiled, and the sheet easily causes streaky irregularities on the sheet surface.
[0027]
Further, it is preferable that the phosphorus compound is contained in an amount of 0.2 to 9 ppm in terms of phosphorus atom with respect to the polyester. When the phosphorus compound is less than 0.2 ppm in terms of phosphorus atoms relative to the polyester, when the polyester is polymerized, the polyester is thermally degraded, and a thermally degraded product is easily generated in the polyester, and the Ra value is more likely to exceed 3.0 nm. Further, the heat-degraded product adheres to the surface of the die slit when discharged from the die slit, and becomes dirty, and the dirt tends to cause streak-like irregularities on the sheet surface, which is not preferable. Conversely, if it exceeds 9 ppm in terms of phosphorus atoms, phosphorus is likely to precipitate in the polyester, and the deposited phosphorus adheres to the surface of the die slit when discharged from the die slit, and becomes a dirt. It is not preferable because unevenness is likely to occur. The ratio of the titanium compound to the phosphorus compound is such that the atomic weight ratio (Ti / P) is in the range of 0.7 to 10 to improve the thermal stability of the polyester and to form the polyester into a film. In particular, it is preferable to prevent thermal deterioration when the polyester chips are melt-extruded, and to further reduce the Ra value to 3.0 nm or less.
[0028]
It is particularly preferred that neither an antimony compound nor a germanium compound is substantially present in the polyester, but even if they are present, it is preferable that each of them is not more than 2 ppm in terms of atoms relative to the polyester. When the amount of the antimony compound and / or the germanium compound exceeds 2 ppm in atom conversion, the antimony compound or the germanium compound in the polyester adheres to the surface of the base slit when discharging from the base slit, and becomes a dirt. This is not preferable because streaky irregularities easily occur.
[0029]
The Ra value of one side surface B of the polyester film of the present invention (the surface opposite to the above-mentioned coating surface A) is determined when the polyester film is formed and then slit into a predetermined width. After the ferromagnetic thin film is provided on one surface of the polyester film, the roughness of one surface B is transferred to the opposite surface by roll-shaped winding. It is desirable that the thickness be 8 to 50 nm, more preferably 10 to 45 nm, in order to minimize the occurrence of undulating deformation in the layer.
[0030]
Further, it is also one side surface B, the depth or height of the number of striped defects in length than 1m above 0.2μm, the one / 2m ² or less, further is one / 20 m ² or less Is desirable. If this streak-like defect exists more than that, the stiffness changes due to the local thickness change of the streak-like defect portion of the magnetic tape, and the accompanying fluctuation in the spacing between the magnetic tape magnetic layer surface and the magnetic head. However, it is not preferable because the signal writing strength on the magnetic tape and the reproduction output are apt to decrease.
[0031]
In order to reduce the number of streak-like defects on the one-sided surface B to 1 / m ² or less, similarly to the case of the reduction of the streak-like defects on the coating surface, a titanium compound as a polyester constituting the one-sided surface is used. The phosphorus compound, the antimony compound, and the amount of the germanium compound are within the above-mentioned specific range, and the polyester is used. The maximum height Rmax of the slit surface in contact with the molten polyester B on one surface B of the slit discharge portion is set to 0.6 μm or less. And a means for periodically cleaning dirt generated and adhered to the surface once every one to seven days.
[0032]
On one surface B side of the polyester film of the present invention, a coarser coating layer containing a lubricant such as silicone is provided, or a polyester film layer containing larger fine particles is formed by lamination, or Further, those provided with the coating layer thereon are preferably used, but are not particularly limited thereto. The fine particles used here include calcium carbonate, silica, alumina, polystyrene and the like. As the fine particles, those having an average particle diameter of preferably 100 to 1000 nm, more preferably 150 to 900 nm are used, and the addition amount thereof is preferably 0.05 to 1.0% by weight, more preferably 0.1 to 1.0% by weight. 08-0.8% by weight is desirable.
[0033]
The polyester film of the present invention preferably has a film thickness of less than 10 μm, more preferably 3.5 to 9.0 μm.
[0034]
The polyester film of the present invention is obtained by discharging a molten polyester into a sheet from a slit of a die to form a sheet, and then, mainly includes a water-soluble polymer or a water-dispersible polymer and fine particles on one surface of the polyester film. A film is formed by applying and drying a water-based coating solution contained as a component, and is produced by a film-forming step of biaxial stretching. As a polyester to be subjected to melt extrusion, a titanium compound is converted to a titanium atom with respect to the polyester by 2 to 2 atoms. -6 ppm, the phosphorus compound is contained in an amount of 0.2-9 ppm in terms of phosphorus atoms relative to the polyester, the amount of the antimony compound is 0-2 ppm in terms of antimony atoms in relation to the polyester, and the amount of the germanium compound is in terms of germanium atoms relative to the polyester. 0 to 2 ppm, and the titanium compound Polyester having a compound ratio of 0.7 to 10 in terms of atomic weight ratio (Ti / P) is used, and the maximum surface height Rmax at the slit discharge portion of the die is set to 0.6 μm or less, and It is important to clean the surface of the slit discharge portion once every 1 to 7 days to remove the adhered contaminants in order to sufficiently reduce the number of streak-like defects on the film surface and the amount of clumps. It is.
[0035]
This polyester can be produced by the following polymerization method using a titanium compound catalyst. As a specific example, the case of polyethylene terephthalate will be described as an example, but the present invention is not limited to this.
[0036]
Polyethylene terephthalate is usually produced by one of the following polymerization processes. That is, (1) a process of obtaining a low polymer by a direct esterification reaction using terephthalic acid and ethylene glycol as raw materials and further obtaining a high molecular weight polymer by a subsequent polycondensation reaction, and (2) a process of using dimethyl terephthalate and ethylene glycol as raw materials. In this process, a low polymer is obtained by a transesterification reaction, and a high molecular weight polymer is obtained by a subsequent polycondensation reaction. Here, the esterification reaction proceeds without a catalyst, but a catalyst may be added. In the transesterification reaction, a catalyst is added to proceed the reaction, and after the transesterification reaction is substantially completed, a phosphorus compound may be added for the purpose of inactivating the catalyst used in the reaction. Done. The above reaction may be performed in any of a batch system, a semi-batch system, and a continuous system.
[0037]
In the case of the polyester used in the present invention, the low weight obtained at any stage of the series of reactions (1) or (2), preferably at the first half of the series of reactions (1) or (2), After adding various additives to the coalescence as needed, a titanium compound catalyst is added as a polycondensation catalyst to carry out a polycondensation reaction to obtain a high molecular weight polyethylene terephthalate.
[0038]
The titanium compound catalyst and the phosphorus compound to be added in the polyester polymerization step may be added to the polyester reaction system as they are, but a solution or slurry prepared by adding a diol-based solvent in advance should be added to the reaction system. Is preferred because the generation of foreign substances in the polymer is further suppressed. The solution or slurry is prepared by mixing a titanium compound catalyst or a phosphorus compound with a solvent containing a polyester-forming diol component such as ethylene glycol or propylene glycol to form a solution or slurry. It can be prepared by removing low boiling components such as alcohol used in the synthesis of the phosphorus compound. When the titanium compound catalyst or the like is added as an esterification reaction catalyst or a transesterification reaction catalyst, it may be added immediately after the addition of the raw material or may be added together with the raw material. In addition, when added as a polycondensation reaction catalyst, it may be substantially before the start of the polycondensation reaction, and before the esterification reaction or the transesterification reaction, or after the completion of these reactions, It may be added before starting. In this case, as a means for suppressing the deactivation of the catalyst due to the contact between the titanium compound and the phosphorus compound, a method of adding the titanium compound and the phosphorus compound to a different reaction tank or a case of adding the titanium compound and the phosphorus compound in the same reaction tank. There is a method of shifting the time of addition for 1 to 15 minutes or a method of separating the addition position.
[0039]
Further, a compound obtained by reacting a titanium compound catalyst with a phosphorus compound in advance can be used as the catalyst. In this case, the following reaction method may be used.
(1) A phosphorus compound is added dropwise to a solution obtained by mixing a titanium compound catalyst in a solvent and dissolving a part or the whole of the catalyst in the solvent with a stock solution or a solution obtained by dissolving and diluting the solvent in the solvent.
(2) When using a ligand of a titanium compound such as a hydroxycarboxylic acid-based compound or a polycarboxylic acid-based compound, the titanium compound or the ligand compound is mixed with a solvent, and a part or all of the mixture is placed in the solvent. A ligand compound or a titanium compound is added dropwise to the dissolved solution as a stock solution or a solution obtained by dissolving and diluting in a solvent. Further, the mixed solution is allowed to react by dropping a phosphorus compound as a stock solution or a solution obtained by dissolving and diluting in a solvent. This reaction method is more preferable from the viewpoint of thermal stability and color tone improvement.
[0040]
The above reaction conditions are carried out by heating at a temperature of 0 to 200 ° C for 1 minute or more, preferably at a temperature of 20 to 100 ° C for 2 to 100 minutes. The reaction pressure at this time is not particularly limited, and may be normal pressure. The solvent used here may be selected from those capable of dissolving part or all of the titanium compound, the phosphorus compound and the carbonyl group-containing compound, but is preferably water, methanol, ethanol, ethylene glycol, or propanediol. And a solvent selected from butanediol, benzene and xylene.
[0041]
As the titanium compound of the polymerization catalyst used in producing the polyester used in the present invention, titanium compounds (including titanium oxide) whose substituents include at least one of the functional groups represented by the following general formula Is mentioned.
[0042]
Embedded image

[0043]
(In Formulas 1 to 6, R1 to R3 each independently represent hydrogen, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group, a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group or an ester group, or an amino group. Represents a hydrocarbon group having 1 to 30 carbon atoms.)
[0044]
Examples of the functional group of the above formula 1 include alkoxy groups such as ethoxide, propoxide, isopropoxide, butoxide, and 2-ethylhexoxide; and hydroxy polycarboxylic acid compounds such as lactic acid, malic acid, tartaric acid, and citric acid. Functional groups. Examples of the functional group of Formula 2 include a functional group composed of a β-diketone compound such as acetylacetone and a ketoester compound such as methyl acetoacetate and ethyl acetoacetate. Examples of the functional group of the above formula 3 include a functional group composed of phenoxy, cresylate, salicylic acid, and the like.
[0045]
Examples of the functional group of the above formula 4 include lactate, an acylate group such as stearate, phthalic acid, trimellitic acid, trimesic acid, hemi-mellitic acid, pyromellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, Adipic acid, sebacic acid, maleic acid, fumaric acid, polycarboxylic compounds such as cyclohexanedicarboxylic acid or anhydrides thereof, ethylenediaminetetraacetic acid, nitrilotripropionic acid, carboxyiminodiacetic acid, carboxymethyliminodipropionic acid, Functional group consisting of a nitrogen-containing polycarboxylic acid such as diethylenetriaminopentaacetic acid, triethylenetetraminohexaacetic acid, iminodiacetic acid, iminodipropionic acid, hydroxyethyliminodiacetic acid, hydroxyethyliminodipropionic acid, and methoxyethyliminodiacetic acid Is mentioned. Examples of the functional group of the above formula 5 include functional groups composed of aniline, phenylamine, diphenylamine, and the like.
[0046]
Among them, a titanium compound catalyst containing a functional group of the formula 1 and / or a functional group of the formula 4 is preferable from the viewpoint of the thermal stability and color tone of the polymer.
[0047]
Specific examples of the titanium compound-based catalyst include titanium diisopropoxybisacetylacetonate and titanium triethanolaminate isopropoxide containing two or more of these substituents of formulas 1 to 6. Examples of the titanium oxide-based catalyst include a composite oxide in which the main metal element is titanium and silicon and ultrafine titanium oxide.
[0048]
In the polymerization step for producing a polyester synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, these titanium compound catalysts are reacted (all or one) in the following (1) to (3). (The elementary reaction of the part).
(1) an esterification reaction which is a reaction between a dicarboxylic acid component and a diol component;
(2) a transesterification reaction which is a reaction between a dicarboxylic acid ester-forming derivative component and a diol component;
(3) a polycondensation reaction in which the esterification reaction or transesterification reaction is substantially completed, and the resulting polyethylene terephthalate low polymer is depolymerized to a higher degree of polymerization,
[0049]
In order to make the polyester contain a predetermined amount of the phosphorus compound, the phosphorus compound may be added in the polyester production process. The phosphorus compound may be any of a phosphoric acid compound, a phosphorous acid compound, a phosphonic acid compound, a phosphinic acid compound, a phosphine oxide compound, a phosphonous acid compound, a phosphinous acid compound, and a phosphine compound. Alternatively, two types may be used. In particular, from the viewpoint of improving the thermal stability and color tone of the polyester, a phosphoric acid-based and / or phosphonic acid-based compound is preferable.
[0050]
Further, for the purpose of improving the color tone of the resulting polymer and the heat resistance of the polymer, an alkali metal compound, an alkaline earth metal compound, an aluminum compound, a zinc compound, a tin compound, a magnesium compound, a manganese compound, a cobalt compound, and the like are added. Is also good.
[0051]
As described above, in the method of the present invention, since a film is produced using a specific polyester, such as an antimony compound or a germanium compound, which has an extremely small amount of 0 to 2 ppm, the film is derived from the precipitation of a catalyst in the polyester. The number of contaminants in the vicinity of the base slit is reduced, and the number of streak-like defects on the film surface and lump-like deposits can be considerably reduced. Nevertheless, since eliminating contamination of a slit near completely is difficult, the number of striped defects in the film surface one / 2m ² or less, and, since the bulk deposits and one / 2m ² or less In addition to using the above-mentioned specific polyester, the maximum height Rmax of the slit surface where the polyester comes into contact with the slit discharge portion of the die is set to 0.6 μm or less, and further, the slit discharge portion surface is changed every 1 to 7 days. In this case, a means is adopted in which cleaning is carried out once to remove adhered dirt.
[0052]
When the maximum height Rmax value of the slit surface where the molten polyester of the slit discharge portion comes into contact exceeds 0.6 μm, it becomes difficult to suppress the number of streak-like defects on the film surface to 1/2 m ² or less. When film production is continued without cleaning the surface of the slit discharge portion or when cleaning is performed at cleaning intervals exceeding 7 days, the number of streak-like defects caused by dirt attached to the molten polyester contact surface of the die slit is reduced. Is difficult to suppress to 1 piece / 2 m ² or less.
[0053]
Next, an example of a method for producing the polyester film and the magnetic recording tape of the present invention will be described.
[0054]
The polyester film of the present invention is a polyester as a raw material of the film, which is a polyester from which contained particles are removed as much as possible, and contains 2 to 6 ppm of a titanium compound derived from a catalyst residue in terms of a titanium atom with respect to the polyester, and a phosphorus compound. Is contained in an amount of 0.2 to 9 ppm in terms of phosphorus atoms with respect to the polyester, the abundance of the antimony compound is 0 to 2 ppm in terms of antimony atoms with respect to the polyester, and the abundance of the germanium compound is 0 to 2 ppm in terms of germanium atoms with respect to the polyester. A polyester in which the ratio of the titanium compound to the phosphorus compound is Ti / P = 0.7 to 10 in terms of atomic weight is used. Using this polyester as a raw material, a film is produced by a usual plastic film production process comprising drying, melting, molding, biaxial stretching and heat setting. For example, a polyester chip is melt-extruded, stretched in the longitudinal direction by a heated stretching roll, then coated with a coating liquid for providing a coating layer on one surface A of the unidirectionally stretched polyester film, and then dried. Alternatively, it is manufactured by stretching in the direction perpendicular to the stretching direction while drying, performing further stretching in the required direction as necessary, and then performing heat treatment. Then, in the stretching step, the film is stretched 2.7 to 5.5 times and 3.5 to 7.0 times vertically and horizontally at 90 to 140 ° C., and heat-set at a temperature of 190 to 220 ° C.
[0055]
In order to produce the polyester film of the present invention, further, the surface maximum height Rmax in the slit discharge portion of the die is set to 0.6 μm or less, and the slit discharge portion is contaminated once every 1 to 7 days. To clean.
[0056]
The film formation on one surface A of the film is performed by the following operation.
On one surface of the smooth polyester film after stretching in the longitudinal direction, an aqueous coating liquid containing a water-soluble polymer or a water-dispersible polymer and fine particles having an average particle size of 5 to 50 nm as main components, Coating is performed so as to have a coating concentration of 3 to 100 mg / m ² . Examples of the water-soluble polymer or the water-dispersible polymer include polyvinyl alcohol, tragacanth rubber, casein, gelatin, a cellulose derivative, a water-soluble polyester, a water-soluble polyester ether copolymer, a polyurethane, an isophthalic acid ester resin, and a methacrylic acid ester resin. Polar polymers and blends thereof can be used, but are not limited thereto.
[0057]
The content of the fine particles in the aqueous coating solution is preferably 0.5 to 12.0% by weight, and more preferably 0.6 to 10.0% by weight. The aqueous solution preferably has a solid application concentration of 3 to 100 mg / m ² . When the solid content concentration is less than 3 mg / m ² , the number of fine surface projections tends to be less than 3,000,000 / mm ² , and the surface roughness Ra value tends to be less than 0.5 nm. When the solid content application concentration exceeds 100 mg / m ² , the number of fine surface projections tends to exceed 100 million / mm ² and the surface roughness Ra value tends to exceed 3.0 nm.
[0058]
By using the co-extrusion technique, the above-mentioned raw material is used as the raw material for the A layer (raw material A), and the raw material for the B layer (raw material B) containing larger fine particles is actively used. May be melt-extruded to form a film, or a coating solution containing a lubricant may be applied to the surface B side opposite to the surface A side without using the layer B, and the surface B side may be easily lubricated. Using the layer B, a coating solution containing a lubricant may be further applied to facilitate the lubrication treatment on the B side.
[0059]
In order to further improve the durability of the magnetic layer, fine particles having a particle size of 50 to 100 nm may be added to the raw material A in an amount of 0.05% by weight or less. Examples of the fine particles include calcium carbonate, silica, alumina, and polystyrene.
[0060]
The biaxial stretching can be performed by, for example, a sequential biaxial stretching method or a simultaneous biaxial stretching method.If desired, before heat setting, the film is further stretched in the vertical or horizontal direction or in the vertical and horizontal directions to reduce the mechanical strength. It can also be an enhanced, so-called enhanced type.
[0061]
The polyester film of the present invention is suitable as a base film of a magnetic recording medium because it can provide excellent results for use in magnetic tapes for recording digital data, particularly for DVCAM magnetic tapes. Further, an alloy film for recording video data made of photoreactive Ge, Sb, Te or the like is formed, and can be suitably used as a base film of an optical recording tape capable of recording video data or the like.
[0062]
The magnetic recording tape of the present invention is provided with a ferromagnetic metal thin film layer formed by vacuum deposition on the coating surface A of the polyester film of the present invention, and is formed into a tape shape. Although it is not particularly limited, those made of a ferromagnetic material of iron, cobalt, nickel, or an alloy thereof are preferable. The thickness of the metal thin film layer is generally 20 to 300 nm.
[0063]
That is, the magnetic recording tape of the present invention forms a ferromagnetic metal thin film made of Co or the like with a film thickness of about 20 to 300 nm on the coating surface A of the polyester film of the present invention by vacuum evaporation, and A diamond-like carbon film having a thickness of about 10 nm is coated, and a lubricant is further applied thereon. On the other hand, a solution containing solid fine particles and a binder and various additives as required is added to one surface B. It can be manufactured by providing a back coat layer by coating, and then cutting to a predetermined tape width. Known solid fine particles, binders and additives can be used and are not particularly limited. The thickness of the back coat layer is preferably about 0.3 to 1.5 μm.
[0064]
【Example】
The measurement method used in this example is shown below.
[0065]
(1) Number of fine surface projections on the film Observing the film surface with a scanning electron microscope at a magnification of 50,000 times for 10 visual fields or more, and measuring how many projections appear in a projection shape per 1 mm ² Then, the number of fine projections formed on the surface of the film was determined.
(2) Diameter of fine surface projections on the film The surface of the film is observed with a scanning electron microscope at a magnification of 50,000 times in five visual fields, and ten projections that look like projections from each visual field are randomly selected. The diameter and the minimum diameter were measured, and the average value was used as the diameter of each projection. The average value of the diameters of 50 projections was determined, and the average value was used as the diameter of the fine surface projections formed on the surface of the film.
[0066]
(3) Surface roughness Ra value and Rz value of film The surface roughness Ra value and Rz value of the film surface were measured using an atomic force microscope (scanning probe microscope). That is, the surface of the film is subjected to an atomic force microscope measurement scan in a damping mode using a desktop miniature probe microscope (“Nanopics” 1000) manufactured by Seiko Instruments Inc. in a range of 4 μm square, and the obtained surface is measured. Ra was determined from the arithmetic average roughness corresponding to JIS B0601 Ra from the profile curve, and Rz value was determined from the ten-point average roughness. The magnification in the in-plane direction was 10,000 to 50,000 times, and the magnification in the height direction was about 1 million times.
[0067]
(4) The number of streak-like defects having a depth or height of 0.2 μm or more and a length of 1 m or more, the number of massive surface deposits having a height of 0.6 μm or more Observation was made within a range of 1 m and 2 m in the longitudinal direction, and the presence of streaks shining linearly in the longitudinal direction was examined. When a streak was present, its length was measured on a scale, and a streak exceeding 1 m was observed using a laser microscope (Surface Profile Measurement Microscope VF-7500) manufactured by Keyence Corporation. Which side of the film is present, and whether the depth or height is 0.2 μm or more is measured on the streak evenly in the longitudinal direction at n = 5, and the average value is calculated. Ask. Judging from the average value, streaks having a depth or height of 0.2 μm or more and a length of 1 m or more were recognized as streak-like defects. From the number and the area of the measurement range, the number was converted into the number per 2 m ² , which was regarded as the number of streak-like defects.
[0068]
Regarding the massive surface deposits having a height of 0.6 μm or more, observation is performed by paying attention to the vicinity of the starting end and the end of the streak. That is, the vicinity of the start end and the end of the streak is observed using a laser microscope (surface shape measurement microscope VF-7500) manufactured by KEYENCE CORPORATION, and there is a massive surface deposit having a height of 0.6 μm or more. I checked. Based on the confirmed number and the area of the measurement range, the number was converted into the number per 2 m ² , which was regarded as the number of aggregated surface deposits.
[0069]
When measuring from a magnetic tape, after performing magnetic recording, a magnetic colloid is applied to the surface of the magnetic tape, and the coated surface is observed by a stereoscopic microscope (observation magnification: 10 times). A check is made to see if there is any streak on the coating surface where the magnetic recording has come off.
In the case of a streak, the height or depth of the streak is measured using a laser microscope (Surface Profile Measurement Microscope VF-7500) manufactured by KEYENCE CORPORATION to confirm whether the length of the streak is 1 m. In addition, it is checked whether or not there is a lump surface adhering material having a height of 0.6 μm or more near the starting end or the end of the streak. From the number and the area of the measurement range, the number was converted into the number per 2 m ^{2 to} obtain the number of streak-like defects and the number of massive surface deposits.
[0070]
(5) Quantities of titanium compound, phosphorus compound, antimony compound, and germanium compound contained in polyester constituting the film X-ray fluorescence elemental analyzer (manufactured by Horiba, Ltd., MESA-500W type) by a fluorescent X-ray (FLX) method. ), The amounts of Ti, P, Sb, and Ge contained in the polyester in the film were quantified. When these elements are not contained in the additive or the coating, the measurement may be performed by using the whole film as a sample.
(6) Intrinsic viscosity IV of polyester
The measurement was performed at 25 ° C. using orthochlorophenol as a solvent.
[0071]
(7) Maximum surface height Rmax value at the surface of the polymer discharge section inside the die slit Before assembling the die slit, a commercially available portable stylus type surface roughness meter (“Hommel Tester” T-1000CG type) was used. Using the cut-off value of 2.5 mm and the measurement length of 25 mm, 10 points were measured in the slit width direction, and the average value of each Rmax value was used as the Rmax value of the surface of the polymer discharge portion inside the die slit. The Rmax value is the difference between the maximum value and the minimum value of the obtained surface profile curve. The magnification in the in-plane direction at the time of measurement was 10,000 to 50,000 times, and the magnification in the height direction was about 1 million times.
[0072]
(8) Characteristics of Magnetic Tape (DVCAM Tape) Using a commercially available DVCAM digital camcorder (“DSR-300” manufactured by Sony), a quiet indoor scene was recorded on a DVCAM standard cassette tape for 180 minutes and then reproduced. The DVCAM tape characteristics were evaluated by counting the number of block mosaics (dropout (DO) numbers) appearing on the screen during the reproduction.
The number of DOs was measured at the time of the first reproduction after recording and after 100 times of reproduction (300 hours), and was indicated by the number of DOs per 3 hours.
[0073]
Next, the present invention will be described based on examples.
[0074]
[Example 1]
Production of polyethylene terephthalate using titanium compound catalyst:
A slurry of 100 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals, Inc.) and 45 kg of ethylene glycol (manufactured by Nippon Shokubai Co., Ltd.) is charged in advance with about 123 kg of bis (hydroxyethyl) terephthalate at a temperature of 250 ° C. and a pressure of 1.2. The mixture was sequentially supplied to the esterification reaction tank maintained at × 10 ⁵ Pa over 4 hours, and after the supply was completed, the esterification reaction was further performed for 1 hour, and 123 kg of the obtained esterification reaction product was supplied to the polycondensation tank. Transferred.
[0075]
Subsequently, an ethylene glycol solution of magnesium acetate was added to the polycondensation reaction tank to which the esterification reaction product had been transferred, so as to be 30 ppm in terms of magnesium atoms with respect to the obtained polymer. After further stirring for 5 minutes, a 2% by weight ethylene glycol solution of the titanium citrate chelate compound was added to the obtained polymer so as to be 5 ppm in terms of titanium atom, and after 5 minutes, 10 mL of ethyl diethylphosphonoacetate was added. A weight% ethylene glycol solution was added to the obtained polymer so as to be 5 ppm in terms of phosphorus atom, and then the reaction system was gradually heated from 250 ° C. to 285 ° C. while stirring the low polymer at 30 rpm. At the same time, the pressure was reduced to 40 Pa. The time required to reach the final temperature and the final pressure was 60 minutes. When the predetermined stirring torque was reached, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, discharged into cold water in the form of a strand, and immediately cut into polymer pellets. The time from the start of the pressure reduction to the arrival of the predetermined stirring torque was 3 hours.
[0076]
The IV of the obtained polymer was 0.66, the melting point of the polymer was 259 ° C., and the solution haze was 0.7%. Further, the content of titanium atoms derived from the titanium catalyst measured from the polymer was 5 ppm, the content of phosphorus atoms was 5 ppm, Ti / P = 1, the content of antimony atoms and the content of germanium atoms were 0 ppm. I confirmed that there is.
[0077]
The titanium citrate chelate compound added as a catalyst in the above polymerization step was a product synthesized by the following method.
[0078]
Citric acid monohydrate (532 g, 2.52 mol) was dissolved in warm water (371 g) in a 3 L flask equipped with a stirrer, condenser and thermometer. Titanium tetraisopropoxide (288 g, 1.00 mol) was slowly added to the stirred solution from a dropping funnel. The mixture was heated at reflux for 1 hour to form a cloudy solution from which the isopropanol / water mixture was distilled under vacuum. The product was cooled to a temperature below 70 ° C. and to the stirring solution was slowly added via a dropping funnel a 32% by weight aqueous solution of NaOH (380 g, 3.04 mol). The resulting product was filtered, then mixed with ethylene glycol (504 g, 80 mol) and heated under vacuum to remove isopropanol / water, giving a slightly cloudy pale yellow citrate chelate titanium compound ( A Ti content of 3.85% by weight) was obtained.
[0079]
Raw material A obtained by polymerizing by the above method and containing 0.03% by weight of silica having an average particle size of 60 nm in polyethylene terephthalate substantially free of inert particles, and the same polyethylene terephthalate having an average particle size of 190 nm Raw material B containing 0.15% by weight of aluminum silicate is melted, discharged in the form of a sheet from a slit of a die at a ratio of 5: 1 in a thickness ratio, brought into close contact with a cooling drum, cooled, and roll-drawn. The film was longitudinally stretched 3.0 times at 110 ° C. by the method.
[0080]
In discharging the polyester from the die slit, the maximum surface height Rmax inside the slit of the die was 0.3 μm on both the raw material A side and the raw material B side. Also, the polymer discharge portion inside the slit of the die was cleaned once every seven days on both the raw material A side and the raw material B side to remove adhered dirt. A smooth flat plate made of copper was used for the cleaning.
[0081]
In the process after the longitudinal stretching, an aqueous solution having the following composition is kept at a temperature of 25 ° C. outside the surface A on the raw material A side and the surface B on the raw material B side, and filtered with a filter having a filtration accuracy of 0.8 μm. Then, the solid content was applied so that the applied amount became 40 mg / m ² and 50 mg / m ² , respectively.
[0082]
Aqueous solution to the outside of A side:

[0083]
Aqueous solution applied to outside of surface B:

[0084]
Thereafter, the film is stretched 4.2 times in a transverse direction at 102 ° C. by a stenter, heat-treated at 215 ° C., wound on an intermediate spool, slit into a small width by a slitter, wound up in a roll on a cylindrical core, and 6.3 μm in thickness. Polyester film.
On the surface A of this polyester film, a cobalt-oxygen thin film was formed with a thickness of 150 nm by vacuum evaporation. Next, a diamond-like carbon film was formed to a thickness of 10 nm on the cobalt-oxygen thin film layer by a sputtering method, and a fluorine-containing fatty acid ester-based lubricant was applied to a thickness of 3 nm. Subsequently, a back coat layer made of carbon black, polyurethane, and silicone was provided on the surface B with a thickness of 500 nm, slit to a width of 6.35 mm by a slitter, and wound on a reel with a 311 m long magnetic tape (standard tape for DVCAM). ) Was prepared.
[0085]
Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0086]
[Example 2]
In the production of the base film of Example 1, polyethylene terephthalate was changed to polyethylene-2,6-naphthalate, and the contents of silica and aluminum silicate in raw materials A and B were changed to 0.075% by weight and 0.45% by weight. The longitudinal stretching temperature and the magnification were changed to 5.0 times at 135 ° C., and the solid content of the outside coating on the A and B sides was changed to 60 mg / m ² and 100 mg / m ^2, and the transverse stretching temperature and The magnification was changed to 135 ° C. and 6.5 times, and the heat treatment was changed to 200 ° C., and the other conditions were the same as in Example 1 to produce a 4.7 μm-thick polyester film. A magnetic tape having a width of 6.35 mm and a length of 417 m was produced from the obtained polyester film in the same manner as in Example 1. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 10 nm and 160 nm.
[0087]
[Example 3]
The production of the base film of Example 1 was the same as that of Example 1 except that silica having an average particle diameter of 60 nm in the raw material A was not used, and the concentration of the ultrafine silica in the coating liquid on the side A was 0.08% by weight. Similarly, a polyester film having a thickness of 6.3 μm was prepared, and a magnetic tape having a width of 6.35 mm and a length of 311 m was prepared. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0088]
[Comparative Example 1]
In the production of the base film of Example 1, the amount of the solid applied when the aqueous solution was applied to the outside of the A side was changed to ² mg / m ² . Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0089]
[Comparative Example 2]
In the production of the base film of Example 1, the concentration of the ultrafine silica in the aqueous coating solution on the outside of the A side was changed to 0.09% by weight, and the solid concentration at the time of coating the aqueous solution was changed to 120 mg / m ² . Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0090]
[Comparative Example 3]
In the production of the base film of Example 1, the particle size of the ultrafine silica in the aqueous coating solution on the outside of the A side was changed to 4 nm, and the solid content concentration when the aqueous solution was applied was changed to 10 mg / m ² . Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0091]
[Comparative Example 4]
In the production of the base film of Example 1, the particle size of the ultrafine silica in the aqueous coating solution on the outside of the A side was changed to 70 nm, and the silica addition concentration was changed to 0.08% by weight. Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0092]
[Comparative Example 5]
A polymer material obtained by mixing conventional general polyethylene terephthalate (antimony catalyst, germanium catalyst) with polyethylene terephthalate obtained by the titanium compound catalyst obtained in Example 1 was used. The element content in the mixed polymer raw material was as shown in Table 1.
[0093]
Antimony-catalyzed polyethylene terephthalate: An ordinary antimony-based catalyst is used as a catalyst to be added in the polyethylene terephthalate polymerization step, and is polymerized by an ordinary method to give polyethylene terephthalate having an IV of 0.66. 0 ppm, phosphorus 10 ppm, antimony 80 ppm, and germanium 0 ppm).
[0094]
Polyethylene terephthalate with germanium catalyst: As a catalyst to be added in the polyethylene terephthalate polymerization step, a normal germanium-based catalyst is polymerized by a normal method, and polyethylene terephthalate having an IV of 0.66 is used. 0 ppm, phosphorus 10 ppm, antimony 0 ppm, and germanium 40 ppm).
[0095]
In the production of the base film of Example 1, the polyester raw material for film production was changed to the above-mentioned mixed polymer raw material. Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0096]
[Comparative Example 6]
In the production of the polyester of Example 1, the addition amount of the titanium citrate chelate compound used as the polymerization catalyst was changed so that the amount of titanium atom conversion with respect to the obtained polymer was 1 ppm, and 10 wt.% Of ethyl diethylphosphonoacetate was further added. % Of the ethylene glycol solution was changed so that the amount of phosphorus atoms converted into the obtained polymer was 1 ppm, and polymerization was carried out in the same manner as in Example 1 except for the polyester having the element content shown in Table 1. Manufactured.
[0097]
Using the obtained polyester, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0098]
[Comparative Example 7]
In the production of the polyester of Example 1, the addition amount of the titanium citrate chelate compound used as the polymerization catalyst was changed so that the amount of titanium atom conversion with respect to the obtained polymer was 10 ppm, and the amount of ethyl diethylphosphonoacetate was 10 wt. % Of the ethylene glycol solution was changed so that the amount of phosphorus atoms converted into the obtained polymer was 6 ppm, and polymerization was carried out in the same manner as in Example 1 except that the polyester having the element content shown in Table 1 was obtained. Manufactured.
[0099]
Using the obtained polyester, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0100]
[Comparative Example 8]
In the production of the polyester of Example 1, the addition amount of the ethylene glycol solution of 10% by weight of ethyl diethylphosphonoacetate was changed so that the amount of phosphorus atom converted to the obtained polymer was 0.1 ppm. Polymerization was carried out in the same manner as in Example 1 to produce a polyester having an element content shown in Table 1.
[0101]
Using the obtained polyester, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0102]
[Comparative Example 9]
In the production of the polyester of Example 1, the addition amount of a 10% by weight solution of ethyl diethylphosphonoacetate in ethylene glycol was changed so that the equivalent amount of phosphorus to the obtained polymer was 12 ppm, and otherwise the same as in Example 1 Was carried out to produce a polyester having an element content shown in Table 1.
[0103]
Using the obtained polyester, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0104]
[Comparative Example 10]
In the production of the base film of Example 1, the polyester raw material was changed to polyethylene terephthalate polymerized with an antimony catalyst produced in Comparative Example 5, and the other conditions were the same as in Example 1 except that a polyester film having a thickness of 6.3 μm was used. Then, a magnetic tape having a width of 6.35 mm and a length of 311 m was prepared. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0105]
[Comparative Example 11]
In the production of the base film in Example 1, the polyester raw material was changed to polyethylene terephthalate polymerized by a germanium catalyst produced in Comparative Example 5, and the other conditions were the same as in Example 1 except that a polyester film having a thickness of 6.3 μm was used. Then, a magnetic tape having a width of 6.35 mm and a length of 311 m was prepared. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0106]
[Comparative Example 12]
In the production of the polyester of Example 1, the addition amount of the titanium citrate chelate compound used as the polymerization catalyst was changed so that the amount of titanium atom conversion with respect to the obtained polymer was 3 ppm, and the amount of ethyl diethylphosphonoacetate was 10% by weight. % Ethylene glycol solution was changed so that the amount of phosphorus atoms in the obtained polymer was 8 ppm, and polymerization was carried out in the same manner as in Example 1 except that the polyester having the element content shown in Table 1 was obtained. Manufactured.
[0107]
Using the obtained polyester, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0108]
[Comparative Example 13]
In the manufacture of the base film of Example 1, the base was changed to a base having a maximum surface height Rmax of 0.8 μm on both the raw material A side and the raw material B side in the slit discharge portion. Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0109]
[Comparative Example 14]
In the production of the base film of Example 1, the cleaning frequency of the polymer discharge portion inside the slit of the base was changed to once every 14 days. Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0110]
[Comparative Example 15]
In the production of the base film of Example 1, the production of the film was continued without cleaning the polymer discharge portion inside the slit of the die. Otherwise, a polyester film having a thickness of 6.3 μm was produced in the same manner as in Example 1, and a magnetic tape having a width of 6.35 mm and a length of 311 m was produced. Table 1 shows the properties of the obtained polyester film and magnetic tape. The Ra value and Rz value of the B surface of the polyester film were 8 nm and 150 nm.
[0111]
[Table 1]

[0112]
【The invention's effect】
When the polyester film for a recording medium of the present invention is used, even when a commercial magnetic tape such as DVCAM is manufactured, a vapor-deposited magnetic tape with extremely low dropout and excellent durability can be obtained.

Claims (7)

A polyester film for a recording medium in which a film containing fine particles and an organic compound is formed on one surface of a polyester film, wherein the surface on the film side is a surface on which a data recording material thin film is formed, The diameter of the fine surface protrusions on the surface of 5 to 60 nm, the number of the fine surface protrusions is 3,000,000 to 100 million / mm ² , the surface roughness Ra value is 0.5 to 3.0 nm, and the depth or height is 0. The number of streak-like defects having a length of ² μm or more and a length of 1 m or more is 1 / m ² or less, and the number of bulk surface deposits having a height of 0.6 μm or more is 1 / m ² or less. Polyester film for a recording medium. The polyester contains 2 to 6 ppm of a titanium compound in terms of titanium atoms with respect to the polyester, the amount of the antimony compound is 0 to 2 ppm in terms of antimony atoms with respect to the polyester, and the amount of the germanium compound is 0 to 2 ppm in terms of germanium atoms with respect to the polyester. The polyester film for a recording medium according to claim 1, wherein: The polyester further contains 0.2 to 9 ppm of a phosphorus compound in terms of phosphorus atoms relative to the polyester, and the ratio of the titanium compound to the phosphorus compound is 0.7 to 10 in terms of atomic weight ratio (Ti / P). The polyester film for a recording medium according to claim 2, wherein: The polyester film for a recording medium according to any one of claims 1 to 3, wherein the polyester is polyethylene terephthalate or polyethylene-2,6-naphthalate. The polyester film for a recording medium according to any one of claims 1 to 4, wherein the polyester film is used for a digital recording type magnetic tape. An aqueous coating liquid containing a water-soluble polymer or a water-dispersible polymer and fine particles as main components on one side surface of the polyester film after the molten polyester is discharged into a sheet from a slit of a die to form a sheet. A method for producing a polyester film for a recording medium according to any one of claims 1 to 5 by forming a coating by applying and drying, and biaxially stretching, wherein the polyester to be melted, The titanium compound contains 2 to 6 ppm in terms of titanium atoms relative to the polyester, the phosphorus compound contains 0.2 to 9 ppm in terms of phosphorus atoms relative to the polyester, and the amount of the antimony compound is 0 to 2 ppm in terms of antimony atom relative to the polyester. The amount of the compound is 0 to 2 ppm in terms of germanium atoms relative to the polyester, First, it is a polyester in which the ratio of a titanium compound and a phosphorus compound is 0.7 to 10 in terms of an atomic weight ratio (Ti / P), and the maximum surface height Rmax at the slit discharge portion of the die is 0.6 μm or less. A method for producing a polyester film for a recording medium, wherein the surface of the slit discharge section is cleaned once every 1 to 7 days. A magnetic recording tape, comprising a ferromagnetic metal thin film layer provided on the surface of the polyester film according to claim 1.