JP3933360B2 - Laminated thermoplastic resin film - Google Patents

Description

【００５６】
ただし、Ｒ₁はメチル基、フェニル基又は水素であり、Ｒ₂はメチル基、フェニル基、水素または官能性基（例えば、エポキシ基、アミノ基、水酸基）であり、ｎは１００〜７０００の数である。
を有するポリシロキサン化合物であり、末端にエポキシ基、アミノ基、水酸基、その他の官能性末端基を有するものがあげられる。上記シロキサン成分は必ずしもホモポリマーである必要はなく、コポリマーまたは数種のホモポリマーの混合体であってもよい。
【００５７】
上記アクリル樹脂成分とシロキサン成分の比率は、重量比で、９８：２〜５０：５０、さらには９５：５〜６０：４０であることが好ましい。
【００５８】
上記皮膜層Ｃ中のシロキサン共重合アクリル樹脂の含有量は１〜３０重量％、更には１〜２０重量％であることが好ましい。この含有量が１重量％未満であると、効果が不充分でブロッキングの発生及び帯電の増加を引き起こし、一方３０重量％を超えると、磁性層の接着性を悪化させたり、ロール状に巻いたときに接触面への転写が発生したり、フィルム走行時に接触ロールの汚れを惹き起こす。
【００５９】
上記皮膜層Ｃを構成する界面活性剤については、特に限定はされないが、ノニオン型界面活性剤、アニオン型界面活性剤、カチオン型界面活性剤などが例示できる。これらの中ノニオン型界面活性剤が好ましい。ノニオン型界面活性剤としては、エステル型、エーテル型、アルキルフェノール型のものが挙げられ、さらに具体的にはポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンモノステアレート、ソルビタンステアレート、ポリオキシエチレンソルビタンモノステアレート等が挙げられる。
【００６０】
これら界面活性剤の具体例としては、ポリオキシエチレンアルキルフェニルエーテル系化合物として、日本油脂株式会社製の商品名「ノニオンＮＳ−２３０」、「同ＮＳ−２４０］、「同ＨＳ−２２０］、「同ＨＳ−２４０」、三洋化成株式式会社製の商品名「ノニポール２００」、「ノニポール４００」、「ノニポール５００」、「オクタポール４０００」；ポリオキシエチレンアルキルエーテル系化合物として、日本油脂株式会社製の商品名「ノニオンＥ−２３０」、「同Ｋ−２２０」、「同Ｋ−２３０」；高級脂肪酸のポリオキシエチレンアルキルエステル系化合物として、日本油脂株式会社製の商品名「ノニオンＳ−１５．４」、「同Ｓ−４０］等を例示することができる。
【００６１】
界面活性剤の含有量は、皮膜層Ｃに対して、５〜４０重量％、さらには５〜４０重量％、特に１０〜４０重量％、就中１２〜３０重量％の範囲が好ましい。
【００６２】
本発明において、皮膜層Ｃの表面粗さRa^Cは０．１〜２ｎｍ、さらには０．５〜１．５ｎｍであることが好ましい。この表面粗さRa^Cが２ｎｍを超える場合には、特に金属薄膜型磁気記録媒体としたときに電磁変換特性が悪化する。一方、このRa^Cが０．１ｎｍ未満の場合は、滑り性が極度に悪化して走行耐久性が不足したり、磁気ヘッドに貼り付いてテープ鳴きを生じたりして実用に供することが出来なくなり易い。
【００６３】
本発明における積層熱可塑性樹脂フィルムは、全厚みが通常２．５〜２０μｍ、好ましくは３．０〜１０μｍ、さらに好ましくは４．０〜１０μｍである。熱可塑性樹脂層Ａの層厚みは、積層フィルムの全厚みの１／２以下、さらには１／３以下、特に１／４以下であることが好ましい。熱可塑性樹脂層Ｂの厚みは、積層フィルムの全厚みの１／２以上、さらには２／３以上、特に３／４以上であることが好ましい。さらに、皮膜層Ｃの厚みは、通常１〜１００ｎｍ、好ましくは２〜５ｎｍ、さらに好ましくは３〜１０ｎｍ、特に好ましくは３〜８ｎｍである。
【００６４】
本発明における積層熱可塑性樹脂フィルムは、従来から知られている、または当業界に蓄積されている方法に準じて製造することができる。そのうち、熱可塑性樹脂層Ａと熱可塑性樹脂層Ｂとの積層構造は、共押し出し法により製造するのが好ましく、皮膜層Ｃは塗布法により設けるのが好ましい。
【００６５】
例えば、積層二軸配向ポリエステルフィルムで説明すると、先ず、不活性粒子Ａ及び（部分ケン化）エステルワックスを均一分散、含有させた熱可塑性樹脂Ａと、必要に応じて不活性粒子Ｂを含有させた熱可塑性樹脂Ｂとを、それぞれ高精度ろ過したのち、押し出し口金内または口金以前（一般に、前者はマルチマニホールド方式、後者はフィードブロック方式と呼ぶ）で溶融状態にて積層複合し、上記好適な厚み比の積層構造となし、次いで口金より融点（Ｔｍ）〜（Ｔｍ＋７０）℃の温度でフィルム状に共押出し、３０〜９０℃の冷却ロールで急冷固化して未延伸積層フィルムを得る。その後、該未延伸積層フィルムを常法に従い、一軸方向（縦方向または横方向）に（Ｔｇ−１０）〜（Ｔｇ＋７０）℃の温度（ただし、Ｔｇ：ポリエステルのガラス転移温度）で２．５〜８．０倍の倍率で、好ましくは３．０〜７．５倍の倍率で延伸し、次いで該延伸方向とは直角方向（一段目延伸が縦方向の場合には、二段目延伸は横方向となる）に（Ｔｇ）〜（Ｔｇ＋７０）℃の温度で２．５〜８．０倍の倍率で、好ましくは３．０〜７．５倍の倍率で延伸する。その際、必要に応じて、縦方向および／または横方向に再度延伸してもよい。すなわち、２段、３段、４段あるいは多段の延伸を行うとよい。面積延伸倍率としては、通常９倍以上、好ましくは１２〜３５倍、さらに好ましくは１５〜３０倍である。
【００６６】
次いで、上記二軸延伸フィルムは、（Ｔｇ＋７０）〜（Ｔｍ−１０）℃の温度、例えば、ポリエチレンテレフタレートフィルムの場合、１８０〜２５０℃で熱固定結晶化する。これによって、優れた寸法安定性が付与される。また、熱固定時間は１〜６０秒が好ましい。
【００６７】
なお、積層熱可塑性樹脂フィルムの製造に際し、熱可塑性樹脂Ａ、Ｂに所望により上記不活性粒子以外の添加剤、例えば安定剤、着色剤、溶融ポリマーの固有抵抗調整剤などを添加含有させることができる。
【００６８】
本発明において、熱可塑性樹脂層Ｂへの皮膜層Ｃの塗設は水性塗液を塗布する方法で行うのが好ましい。
【００６９】
塗布は最終延伸処理を施す以前の熱可塑性樹脂層Ｂの表面に行い、塗布後にはフィルムを少なくとも一軸方向に延伸するのが好ましい。この延伸の前ないし途中で塗膜は乾燥される。その中で、塗布は未延伸積層フィルムまたは縦（一軸）延伸積層フィルム、特に縦（一軸）延伸積層フィルムに行うのが好ましい。塗布方法としては特に限定されないが、例えばロールコート法、ダイコート法などが好ましく挙げられる。
【００７０】
上記塗液、特に水性塗液の固形分濃度は０．２〜８重量％、さらに０．３〜６重量％、特に０．５〜４重量％であることが好ましい。そして、塗液（好ましくは水性塗液）には、本発明の効果を妨げない範囲で、他の成分、例えば安定剤、分散剤、紫外線吸収剤、増粘剤などを添加することができる。
【００７１】
本発明において、磁気記録媒体としてのヘッドタッチ、走行耐久性を始めとする各種性能を向上させ、同時に薄膜化を達成するために、積層フィルムのヤング率を縦方向および横方向でそれぞれ、４．４ＧＰａ 以上および５．９ＧＰａ以上、さらに４．７ＧＰａ 以上および６．７ＧＰａ 以上、特に５．４ＧＰａ以上および７．８ＧＰａ 以上、就中５．５ＧＰａ以上および９．８Ｇｐａ以上とするのが好ましい。
【００７２】
また、熱可塑性樹脂層Ａ、Ｂの結晶化度は、熱可塑性樹脂がポリエチレンテレフタレートの場合は３０〜５０％、ポリエチレン−２，６−ナフタレートの場合は２８〜３８％であることが望ましい。いずれも下限を下回ると、熱収縮率が大きくなるし、一方、上限を上回るとフィルムの耐摩耗性が悪化し、ロールやガイドピン表面と摺動した場合に白粉が生じやすくなる。
【００７３】
本発明の積層熱可塑性樹脂フィルムは磁気記録媒体の支持体として好ましく使用される。この積層熱可塑性樹脂フィルムを磁気記録媒体の支持体として使用する場合の好ましい実施態様は、下記の通りである。
【００７４】
本発明の積層熱可塑性樹脂フィルムは、皮膜層Ｃの表面に、真空蒸着、スパッタリング、イオンプレーティングなどの方法により、鉄、コバルト、クロムまたはこれらを主成分とする合金もしくは酸化物よりなる強磁性金属薄膜層を形成し、またその表面に、目的、用途、必要に応じてダイアモンドライクカーボン（ＤＬＣ）などの保護層、含フッ素カルボン酸系潤滑層を順次設け、さらに必要により、熱可塑性樹脂層Ａの磁性層とは反対側の表面に、公知の方法でバックコート層を設けることにより、特に短波長領域での出力、Ｓ／Ｎ、Ｃ／Ｎなどの電磁変換特性に優れ、ドロップアウト、エラーレートの少ない高密度記録用蒸着型磁気記録媒体とすることができる。この蒸着型磁気記録媒体は、アナログ信号記録用Ｈｉ８、ディジタル信号記録用ディジタルビデオカセットレコーダー（ＤＶＣ）、データ８ミリ、ＤＤＳIV用磁気テープ媒体として極めて有用である。
【００７５】
また、本発明の積層熱可塑性樹脂フィルムは、皮膜層Ｃの表面に、鉄または鉄を主成分とする針状微細磁性粉（メタル粉）をポリ塩化ビニル、塩化ビニル・酢酸ビニル共重合体などのバインダーに均一に分散し、磁性層厚みが１μｍ以下、好ましくは０．１〜１μｍとなるように塗布し、さらに必要により、熱可塑性樹脂層Ａの磁性層とは反対側の表面に、公知の方法でバックコート層を設けることにより、特に短波長領域での出力、Ｓ／Ｎ、Ｃ／Ｎなどの電磁変換特性に優れ、ドロップアウト、エラーレートの少ない高密度記録用メタル塗布型磁気記録媒体とすることができる。また、必要に応じて、皮膜層Ｃの表面に、上記メタル粉含有磁性層の下地層として微細な酸化チタン粒子などを含有する非磁性層を磁性層と同様の有機バインダー中に分散し、塗設することもできる。このメタル塗布型磁気記録媒体は、アナログ信号記録用８ミリビデオ、Ｈｉ８、βカムＳＰ、Ｗ−ＶＨＳ、ディジタル信号記録用ディジタルビデオカセットレコーダー（ＤＶＣ）、データ８ミリ、ＤＤＳIV、ディジタルβカム、Ｄ２、Ｄ３、ＳＸなど用磁気テープ媒体として極めて有用である。
【００７６】
さらに、本発明の積層熱可塑性樹脂フィルムは、皮膜層Ｃの表面に、酸化鉄または酸化クロムなどの針状微細磁性粉、またはバリウムフェライトなどの板状微細磁性粉をポリ塩化ビニル、塩化ビニル・酢酸ビニル共重合体などのバインダーに均一に分散し、磁性層厚みが１μｍ以下、好ましくは０．１〜１μｍとなるように塗布し、さらに必要により、熱可塑性樹脂層Ａの磁性層とは反対側の表面に、公知の方法でバックコート層を設けることにより、特に短波長領域での出力、Ｓ／Ｎ、Ｃ／Ｎなどの電磁変換特性に優れ、ドロップアウト、エラーレートの少ない高密度記録用酸化物塗布型磁気記録媒体とすることができる。また、必要に応じて、皮膜層Ｃの表面に、上記酸化物粉末含有磁性層の下地層として微細な酸化チタン粒子などを含有する非磁性層を磁性層と同様の有機バインダー中に分散し、塗設することもできる。この酸化物塗布型磁気記録媒体は、ディジタル信号記録用データストリーマー用ＱＩＣなどの高密度記録用酸化物塗布型磁気記録媒体として有用である。
【００７７】
上記のＷ−ＶＨＳはアナログのＨＤＴＶ信号記録用ＶＴＲであり、またＤＶＣはディジタルのＨＤＴＶ信号記録用として適用可能なものである。それゆえ、本発明の積層熱可塑性樹脂フィルムは、これらＨＤＴＶ対応ＶＴＲ用磁気記録媒体に極めて有用なベースフィルムということができる。
【００７８】
【実施例】
以下、実施例を挙げ、本発明をさらに具体的に説明するが、本発明はこれら実施例により限定されるものではない。なお、実施例および比較例における「部」および「％」は、特に断らない限り重量部および重量％である。また、本発明における物性値および特性は、それぞれ下記の方法で測定し、かつ定義されるものである。
【００７９】
（１）固有粘度
オルソクロロフェノール溶媒中３５℃で測定した値から求めた。
【００８０】
（２）粒子の平均粒径（Ｉ）（平均粒径：６０ｎｍ以上）
株式会社島津製作所製「ＣＰ−５０型セントリヒューグル パーティクル サイズ アナライザー（Ｃｅｎｔｒｉｆｕｇａｌ Ｐａｒｔｉｃｌｅ Ｓｉｚｅ Ａｎａｌｙｚｅｒ）」を用いて測定する。得られる遠心沈降曲線を基に算出した各粒径の粒子とその存在量との積算曲線から、５０マスパーセントに相当する粒径「等価球直径」を読み取り、この値を上記平均粒径（ｎｍ）とする（「粒度測定技術」日刊工業新聞社発行、１９７５年、頁２４２〜２４７）。
【００８１】
（３）粒子の平均粒径（II）（平均粒径：６０ｎｍ未満）
小突起を形成する平均粒径６０ｎｍ未満の粒子は、光散乱法を用いて測定する。すなわち、ニコンプインストゥルメント株式会社（Ｎｉｃｏｍｐ Ｉｎｓｔｒｕｍｅｎｔｓ Ｉｎｃ．）製の商品名「ＮＩＣＯＭＰ ＭＯＤＥＬ ２７０ ＳＵＢＭＩＣＲＯＮ ＰＡＲＴＩＣＬＥ ＳＩＺＥＲ」により求められる全粒子の５０％の点にある粒子の「等価球直径」をもって、平均粒径（ｎｍ）とする。
【００８２】
（４）熱可塑性樹脂層Ａ、Ｂの厚み、およびフィルム全体の厚み
フィルム全体の厚みはマイクロメーターにてランダムに１０点測定し、その平均値を用いる。熱可塑性樹脂層Ａ、Ｂの層厚については、薄い熱可塑性樹脂層の層厚みを下記に述べる方法にて測定し、厚い熱可塑性樹脂層の層厚みは、全厚みより塗膜層および薄い熱可塑性樹脂層の層厚を引き算して求める。すなわち、二次イオン質量分析装置（ＳＩＭＳ）を用いて、被覆層を除いた表層から深さ５，０００ｎｍの範囲のフィルム中の粒子の内最も高濃度の粒子に起因する金属元素（Ｍ+ ）と熱可塑性樹脂（ポリエステル）の炭化水素（Ｃ+ ）の濃度比（Ｍ+ ／Ｃ+ ）を粒子濃度とし、表面から深さ５，０００ｎｍまで厚さ方向の分析を行った。表層では表面という界面のために粒子濃度は低く、表面から遠ざかるにつれて粒子濃度は高くなる。本発明の場合、粒子濃度は一旦安定値１になったのち、上昇して安定値２になる場合と、単調に減少する場合とがある。この分布曲線をもとに、前者の場合は、（安定値１＋安定値２）／２の粒子濃度を与える深さをもって、また後者の場合は粒子濃度が安定値１の１／２になる深さ（この深さは安定値１を与える深さよりも深い）をもって、薄い熱可塑性樹脂層の厚み（μｍ）とする。
【００８３】
測定条件は、以下のとおりである。
（ａ）測定装置
二次イオン質量分析装置（ＳＩＭＳ）；パーキン・エルマー株式会社（ＰＥＲＫＩＮ ＥＬＭＥＲ ＩＮＣ．）製、「６３００」
（ｂ）測定条件
一次イオン種：Ｏ2+
一次イオン加速電圧：１２ＫＶ
一次イオン電流：２００ｎＡ
ラスター領域：４００μｍ□
分析領域：ゲート３０％
測定真空度：６．０×１０-9Ｔｏｒｒ
Ｅ−ＧＵＮＮ：０．５ＫＶ−３．０Ａ
なお、表層から５，０００ｎｍの範囲に最も多く存在する粒子がシリコーン樹脂以外の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ＦＴ−ＩＲ（フーリエトランスフォーム赤外分光法）、粒子によってはＸＰＳ（Ｘ線光電分光法）などで上記同様の濃度分布曲線を測定し、層厚（μｍ）を求める。
【００８４】
（５）皮膜層Ｃの厚み
フィルムの小片をエポキシ樹脂にて固定成形し、ミクロトームにて約６００オングストロームの厚みの超薄切片（フィルムの流れ方向に平行に切断する）を作成する。この試料を透過型電子顕微鏡（株式会社日立製作所製：Ｈ−８００型）にて観察し、塗膜層Ｃの境界面を探して塗膜層の厚み（ｎｍ）を求める。
【００８５】
（６）接触角
協和科学（株）製、接触角測定装置を用いて測定する。フィルムサンプルを温度２５℃、湿度５０％の環境下に２４時間以上置いたのち、フィルム上に蒸留水を５ｍｇ滴下し、水平の方向から２０秒後に写真を撮影する。フィルムと水滴の接線が形成する角度を接触角（°）とする。
【００８６】
（７）フィルムの表面粗さ（中心線平均粗さ：Ｒａ）
中心線平均粗さ（Ｒａ）はＪＩＳ−Ｂ６０１に準じて測定する。本発明では（株）小坂研究所の触針式表面粗さ計（SURFCORDER SE，30C）を用い、次の条件で測定して求める。
（ａ）触針先端半径：２μｍ
（ｂ）測定圧力 ：３０ｍｇ
（ｃ）カットオフ ：０．０８ｍｍ
（ｄ）測定長 ：８．０ｍｍ
（ｅ）データのまとめ方：同一試料について６回繰返し測定し、最も大きい値を１つ除き、残りの５つのデータを用いて平均値として中心線平均粗さ（Ｒａ）を求める。
【００８７】
（８）ヤング率
東洋ボールドウィン株式会社製の引っ張り試験機、商品名「テンシロン」を用いて、温度２０℃、湿度５０％に調節された室内において、長さ３００ｍｍ、幅１２．７ｍｍの試料フィルムを１０％／分のひずみ速度で引っ張り、引っ張り応力−ひずみ曲線の初めの直線部分を用いて下式（Ｖ）によって計算する。
【００８８】
【数１】
Ｅ＝△σ／△ε ・・・（Ｖ）
ここで、Ｅはヤング率（Ｇｐａ）、△σは直線上の２点間の元の平均断面積による応力差、△εは同じ２点間のひずみ差である。
【００８９】
（９）ブロッキング剥離力
ロール状フィルムの長手方向に１００ｍｍ、幅方向に２００ｍｍの長方形にサンプリングし、熱可塑性樹脂層Ａ（ベースフィルム）側に、室温２０±２℃、湿度４０±５％の環境下で、コロナ処理を施す。
上記コロナ処理は、春日電気株式会社製、商品名「ＣＧ−１０２」型の高周波電源を用いて、以下の条件にて処理する。
電流：４．５Ａ
電極間距離：１．０ｍｍ
処理時間：１．２ｍ／分の速度で、電極間を通過させて処理。
フィルムの処理した面を、直ちにフィルムの熱可塑性樹脂層Ａと反対側の面と接触させ、１０Ｍｐａの圧力にて温度６０℃、湿度８０％の環境下で１７時間エイジングさせたのち、上記引っ張り試験機、商品名「テンシロン」を用いて、幅１００ｍｍ当たりの剥離力を求める。
【００９０】
（１０）巻き取り性
スリット時の巻き取り条件を最適化したのち、幅６００ｍｍ×１２，０００ｍのサイズで、３０ロールを速度１００ｍ／分でスリットし、スリット後のフィルム表面に、ブツ状、突起やシワのないロールを良品として、以下の基準にて巻き取り性を評価する。
◎；良品ロールの本数２８本以上
○；良品ロールの本数２５〜２７本
×；良品ロールの本数１６〜２４本
××；良品ロールの本数１５本以下
【００９１】
（１１）バックコート塗布適性（加工適性）
下記磁気テープの製造加工工程において、バックコート塗布後の熱可塑性樹脂層Ａの表面を目視観察し、以下の基準にて評価する。
○；バックコート層に、塗布斑、ハジキがない
×；バックコート層に、塗布斑か、ハジキが認められる
【００９２】
（１２）磁気テープの製造および特性（電磁変換特性）評価
積層熱可塑性樹脂フィルムの皮膜層Ｃの表面に、真空蒸着法により、コバルト１００％の強磁性薄膜を０．２μｍの厚みになるように２層（各層厚約０．１μｍ）形成する。形成した強磁性薄膜の表面にダイヤモンドライクカーボン（ＤＬＣ）膜、さらに含フッ素カルボン酸系潤滑層を順次設け、さらに熱可塑性樹脂層Ａの表面に、公知の方法でバックコート層を設ける。その後、８ｍｍ幅にスリットし、市販の８ｍｍビデオカセットにローディングする。次いで、下記の市販の機器を用いてテープの特性（Ｃ／Ｎ）を測定する。
使用機器：８ｍｍビデオテープレコーダー、ソニー株式会社製、商品名「ＥＤＶ−６０００」
Ｃ／Ｎ測定：株式会社シバソク製、ノイズメーター
記録波長０．５μｍ（周波数約７．４ＭＨｚ）の信号を記録し、その再生信号の６．４ＭＨｚと７．４ＭＨｚの値の比をそのテープのＣ／Ｎとし、市販８ｍｍビデオ用蒸着テープのＣ／Ｎを０ｄＢとし、相対値で評価する。
【００９３】
（１３）不活性粒子Ａ、Ｂの調製
不活性粒子Ａとして、下記のものを使用。
真球状シリカ；平均粒径６００ｎｍ
θ型アルミナ；平均粒径６０ｎｍ
シリコーン；平均粒径５００ｎｍ
架橋ポリスチレン；平均粒径８００ｎｍ
不活性粒子Ｂとして、下記のものを使用。
球状シリカ；平均粒径６０ｎｍ
【００９４】
（１４）（部分ケン化）エステルワックスの調製
炭素数が８個以上の脂肪族モノカルボン酸および多価アルコールからなる（部分ケン化）エステルワックスとして下記のものを使用。
（ａ−１）：ソルビタントリステアレート（融点５５℃）
（ａ−２）：モンタン酸ジオールエステルを水酸化カルシウムでケン化したもの、ヘキスト株式会社製、商品名「ワックスＥ」、（融点８６℃）
（ａ−３）：グリセリントリパルミタート
【００９５】
［実施例１］
ジメチルテレフタレートとエチレングリコールとを、エステル交換触媒として酢酸マンガン、重合触媒としてトリメリット酸チタン、安定剤として亜リン酸を、さらに滑剤（不活性粒子Ｂ）として平均粒径６０ｎｍの球状シリカを、樹脂中に０．０３％添加して、常法により重合し、固有粘度０．６０の熱可塑性樹脂層Ｂ用のポリエチレンテレフタレート（樹脂Ｂ１）を得た。
【００９６】
さらに、上記と同様の方法で、滑剤（不活性粒子Ａ）として、平均粒径６００ｎｍの真球状シリカおよび平均粒径６０ｎｍのθ型アルミナを、樹脂中にそれぞれ０．１２％および０．２％添加して、常法により重合し、固有粘度０．６０のポリエチレンテレフタレートを得た。
【００９７】
得られたポリエチレンテレフタレート９９．７％に、ソルビタントリステアレート（ａ−１）の粉末０．３％をまぶし、ベント付き二軸ルーダーにて練り込み、固有粘度０．５９の熱可塑性樹脂層Ａ用のポリエチレンテレフタレート（樹脂Ａ１）を得た。
【００９８】
得られた樹脂Ａ１、樹脂Ｂ１を、それぞれ１７０℃で３時間乾燥後、２台の押し出し機に供給し、溶融温度２８０〜３００℃にて溶融し、平均目開き１１μｍの鋼線フィルターで高精度ろ過したのち、マルチマニホールド型共押し出しダイを用いて、樹脂層Ａの片面に樹脂層Ｂを積層させ、急冷して厚さ８９μｍの積層未延伸フィルムを得た。
【００９９】
得られた積層未延伸フィルムを予熱し、さらに低速・高速のロール間でフィルム温度１００℃にて３．３倍に延伸し、急冷して縦延伸フィルムを得た。次いで縦延伸フィルムの層Ｂ面側に下記に示す組成（固形分換算）の水性塗液（全固形分濃度１．０％）を皮膜層Ｃとしてキスコート法により塗布した。
【０１００】

【０１０１】
続いて、ステンターに供給し、１１０℃にて横方向に４．２倍に延伸した。得られた二軸延伸フィルムを２２０℃の熱風で４秒間熱固定し、全厚み６．４μｍ、ベース層（熱可塑性樹脂層Ａ）厚み１．０μｍの積層二軸配向ポリエステルフィルムを得た。この積層二軸配向フィルムの熱可塑性樹脂層Ａ、Ｂの厚みについては、２台の押し出し機の吐出量により調整した。この積層フィルムのヤング率は縦方向４．９ＧＰａ 、横方向６．９ＧＰａであった。この積層二軸配向フィルムのその他の特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１０２】
［実施例２］
熱可塑性樹脂層Ａに含有させる不活性粒子Ａの種類、平均粒径及び添加量、かつ（部分ケン化）エステルワックスの種類及び添加量を表１に示すとおりに変更し、熱可塑性樹脂Ｂに粒子を含有させない以外は、実施例１と同様にして積層二軸配向ポリエステルフィルムを得た。得られた積層二軸配向フィルムの特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１０３】
［実施例３］
熱可塑性樹脂層Ａに含有させる不活性粒子Ａの種類、平均粒径及び添加量、かつ（部分エステル化）エステルワックスの種類及び添加量を表１に示すとおり変更する以外は、実施例１と同様にして積層二軸配向ポリエステルフィルムを得た。得られた積層二軸配向フィルムの特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１０４】
［実施例４］
熱可塑性樹脂層Ａに含有させる不活性粒子Ａの種類、平均粒径及び添加量、かつ（部分ケン化）エステルワックスの種類及び添加量を表１に示すとおり変更し、ジメチルテレフタレートの代わりに２，６−ナフタレンジカルボン酸ジメチルを同モル量使用した以外は、実施例１と同様にして熱可塑性樹脂層Ａ、Ｂ用のポリエチレン−２，６−ナフタレート（ＰＥＮ）（樹脂Ａ２、Ｂ２）を得た。
【０１０５】
この樹脂Ａ２、Ｂ２を、それぞれ１７０℃で６時間乾燥後、実施例１と同様にして、各層厚みを調整し、厚さ８９μｍの積層未延伸フィルムを得た。
【０１０６】
得られた積層未延伸フィルムを予熱し、さらに低速・高速のロール間でフィルム温度１３５℃にて３．６倍に延伸し、急冷して縦延伸フィルムを得た。次いで縦延伸フィルムの層Ｂ面側に表１に示す組成（固形分換算）の水性塗液（全固形分濃度１．０％）を皮膜層Ｃとして実施例１と同様に塗布した。
【０１０７】
続いて、ステンターに供給し、１５５℃にて横方向に５．７倍に延伸した。得られた二軸延伸フィルムを、２００℃の熱風で４秒間熱固定し、全厚み４．４μｍ、ベース層（熱可塑性樹脂層Ａ）厚み０．６μｍの積層二軸配向ポリエステルフィルムを得た。この積層二軸配向フィルムの熱可塑性樹脂層Ａ、Ｂの厚みについては、２台の押し出し機の吐出量により調整した。このフィルムのヤング率は縦方向５．４ＧＰａ 、横方向１０．３ＧＰａであった。この積層フィルムのその他の特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１０８】
［実施例５］
熱可塑性樹脂Ｂに粒子を含有させない以外は実施例４と同様にして積層二軸配向ポリエステルフィルムを得た。得られた積層二軸配向フィルムの特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１０９】
［比較例１］
熱可塑性樹脂層Ａに（部分ケン化）エステルワックスを含有させず、かつ皮膜層Ｃを設けない以外は、実施例１と同様にして積層二軸配向ポリエステルフィルムを得た。得られた積層二軸配向フィルムは、ブロッキング剥離力を測定する際に、フィルムが密着しており、むりやり剥がそうとすると破れてしまった。その他の特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１１０】
［比較例２］
ソルビタントリステアレート（ａ−１）の添加量を１２％にした以外は、実施例１と同様にして積層二軸配向ポリエステルフィルムを得た。得られた積層二軸配向フィルムは、磁気テープの製造工程においてバックコートに塗布する際、ハジキが発生してしまい、通常の塗布ができなかった。その他の特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１１１】
［比較例３］
熱可塑性樹脂層Ａに不活性粒子を含有させず、かつ皮膜層Ｃを設けない以外は、実施例４と同様にして積層二軸配向ポリエステルフィルムを得た。得られた積層二軸配向フィルムは、ブロッキング剥離力を測定する際に、フィルムが密着しており、測定不能であった。その他の特性、およびこのフィルムを用いた強磁性薄膜蒸着型磁気テープの特性を表１に示す。
【０１１２】
【表１】

【０１１３】
表１から明らかなように、本発明による積層二軸配向ポリエステルフィルムは、片面が非常に平坦で、優れた電磁変換特性を示すとともに、巻き取り性が極めて良好であり、かつ耐ブロッキング性が良好である。一方、本発明の要件を満たさないものは、これらの特性を同時に満足できない。
【０１１４】
【発明の効果】
本発明によれば、耐ブロッキング性、巻き取り性、加工適性に優れ、また金属蒸着薄膜型磁気記録媒体の支持体とて用いると電磁変換特性に優れる、積層熱可塑性樹脂フィルムを提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminated thermoplastic resin film, and more specifically, a laminated thermoplastic resin having excellent blocking resistance, winding property and processability, and excellent electromagnetic conversion characteristics when used as a support for a metal-deposited thin film magnetic recording medium. Related to film.
[0002]
[Prior art]
In recent years, the progress of high-density magnetic recording media has been remarkable. For example, a ferromagnetic metal thin film type magnetic film in which a ferromagnetic metal thin film is formed on a nonmagnetic support by a physical deposition method such as vacuum deposition or sputtering or a plating method. Development and commercialization of recording media are in progress. For example, a Co vapor deposition tape (Japanese Patent Laid-Open No. 54-147010) and a perpendicular magnetic recording medium (Japanese Patent Laid-Open No. 52-134706) made of a Co—Cr alloy are known.
[0003]
Conventional coating-type magnetic recording media (magnetic recording media in which magnetic powder is mixed in an organic polymer binder and coated on a nonmagnetic support) have a low recording density and a long recording wavelength. Thickness is as thick as about 2 μm or more. On the other hand, the metal thin film formed by thin film forming means such as vacuum deposition, sputtering or ion plating has a very thin thickness of 0.2 μm or less.
[0004]
For this reason, in the above high-density magnetic recording medium, the surface state of the nonmagnetic support (base film) greatly affects the surface properties of the magnetic recording layer. That is, the surface state of the non-magnetic support appears as it is as irregularities on the surface of the magnetic recording layer, which causes noise in recording / reproducing signals. Therefore, it is desirable that the surface of the nonmagnetic support is as smooth as possible.
[0005]
On the other hand, from the viewpoint of handling such as film formation of a non-magnetic support, conveyance in processing steps, scratches, winding, unwinding, if the film surface is too smooth, film slipperiness, for example, film-film mutual slipperiness As a result, the yield of the product decreases, and the manufacturing cost of the product increases. Therefore, from the viewpoint of manufacturing cost, the surface of the nonmagnetic support is preferably as rough as possible.
[0006]
As described above, the surface of the nonmagnetic support is required to be smooth from the viewpoint of electromagnetic conversion characteristics, and is required to be rough from the viewpoint of handling properties and manufacturing cost.
[0007]
Furthermore, in the case of a metal thin film type magnetic recording medium, in order to improve the adhesion between the metal thin film and the base film, there is a process called ion bombardment treatment that activates the base film surface with ions before forming the metal thin film. Applied. And at the time of metal thin film shaping | molding, back surface cooling is given so that a high temperature heat may be applied to the film surface, a base film may melt | dissolve, or a physical property, such as a mechanical characteristic, may not fall. As a method of cooling the back surface, the base film is often wound around a drum-shaped cooling body, and at that time, both ends of the base film are masked so that a metal thin film is not formed on the drum surface.
[0008]
Therefore, at both ends of the film roll that has passed through the vapor deposition process of the metal thin film, the surface is activated by the ion bombardment process, and there are portions where the metal thin film is not formed continuously in the longitudinal direction. When this portion is wound up in a roll shape, it comes into contact with the opposite surface side with a high pressure and is likely to cause blocking.
[0009]
When manufacturing a metal thin film type magnetic recording medium, a back coat layer and, if necessary, a top coat layer are usually provided after the metal thin film is deposited. In these processing steps, the above-mentioned blocking occurs in the deposited film roll. If it is, the film is likely to be cut or wrinkled when the film is unwound from the roll, and the yield is greatly reduced.
[0010]
In order to solve the above problems, for example, Japanese Patent Application Laid-Open Nos. 9-207290 and 9-226063 include two resin layers A and B, and the surface of the B layer is more than the surface of the A layer. A rougher laminated film has been proposed. However, with such a method, although the balance between electromagnetic conversion characteristics and handling properties and winding properties can be achieved to some extent, it is still insufficient and the occurrence of blocking cannot be suppressed.
[0011]
[Problems to be solved by the invention]
The object of the present invention is to eliminate such disadvantages of the prior art, excellent in blocking resistance, winding property and processability, and excellent in electromagnetic conversion characteristics when used for a metal vapor-deposited thin film magnetic recording medium support. The object is to provide a laminated thermoplastic resin film.
[0012]
[Means for Solving the Problems]
The object of the present invention is that, according to the present invention, a thermoplastic resin layer A is laminated on one surface of a thermoplastic resin layer B, and a binder resin, inert particles C, a surfactant and a siloxane copolymer are laminated on the other surface. A laminated film in which a film layer C made of an acrylic resin is coated, wherein the thermoplastic resin layer A contains 0.001 to 5% by weight (layer A) of inert particles A having an average particle size of 100 to 2,000 nm. 0.001 to 10% by weight of ester wax (based on layer A), which may be partially saponified, consisting of an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol It is achieved by a laminated thermoplastic resin film characterized in that the water contact angle of the surface of the thermoplastic resin layer A that is not in contact with the thermoplastic resin layer B is 70 to 90 °.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the thermoplastic resins A and B constituting the thermoplastic resin layer A and the thermoplastic resin layer B are polyester resin, polyamide resin, polyimide resin, polyether resin, polycarbonate resin, Examples thereof include polyvinyl resins and polyolefin resins. Of these, polyester resins, particularly aromatic polyesters are preferred. The thermoplastic resins A and B may be of different types, but the same type is preferred.
[0014]
Examples of the aromatic polyester include polyethylene terephthalate, polyethylene isophthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalate (polyethylene-2,6-naphthalenedicarboxylate). Etc. can be illustrated. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalate are particularly preferred.
[0015]
These aromatic polyesters may be homopolyesters or copolyesters. In the case of a copolyester, for example, as a copolymer component of polyethylene terephthalate or polyethylene-2,6-naphthalate, diethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, polyethylene glycol, 1,4-cyclohexanedimethanol , Other diol components such as p-xylylene glycol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (in the case of polyethylene-2,6-naphthalate), 2,6-naphthalenedicarboxylic acid (however, In the case of polyethylene terephthalate), other dicarboxylic acid components such as 5-sodium sulfoisophthalic acid, and oxycarboxylic acid components such as p-oxyethoxybenzoic acid Kill. The amount of these copolymer components is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total acid components forming the polymer.
[0016]
Furthermore, trifunctional or more polyfunctional compounds such as trimellitic acid and pyromellitic acid can be copolymerized. In this case, the copolymer is preferably copolymerized in an amount that is substantially linear, for example, 2 mol% or less.
[0017]
The copolymer component in the case of other polyesters other than polyethylene terephthalate and polyethylene-2,6-naphthalate may be considered in the same manner as described above.
[0018]
The thermoplastic resins A and B are known per se and can be produced by a method known per se.
[0019]
The thermoplastic resin layer A in the present invention contains 0.001 to 5% by weight (based on the layer A) of inert particles having an average particle size of 100 to 2,000 nm (hereinafter referred to as inert particles A).
[0020]
Preferred examples of the inert particles A include (1) heat-resistant polymer particles (for example, crosslinked silicone resin, crosslinked polystyrene, crosslinked acrylic resin, melamine-formaldehyde resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, (2) metal oxides (for example, aluminum sesquioxide, titanium dioxide, silicon dioxide, magnesium oxide, zinc oxide, zirconium oxide, etc.), (3) metal carbonates ( For example, magnesium carbonate, calcium carbonate, etc.), (4) metal sulfate (eg, calcium sulfate, barium sulfate, etc.), (5) carbon (eg, carbon black, graphite, diamond, etc.), and (6) clay mineral (For example, kaolin, clay, ben Knight and the like) and the fine particles of inorganic compounds such as. Among these, crosslinked silicone resin particles, crosslinked polystyrene resin particles, melamine-formaldehyde resin particles, polyamideimide resin particles, other aluminum sesquioxides (alumina), titanium dioxide, silicon dioxide, zirconium oxide, synthetic calcium carbonate, barium sulfate, diamond And fine particles comprising kaolin are preferred. More preferred are fine particles comprising crosslinked silicone resin particles, crosslinked polystyrene resin particles, other aluminum sesquioxide (alumina), titanium dioxide, silicon dioxide, and calcium carbonate.
[0021]
The average particle diameter (dA) of the inert particles A is 100 to 2,000 nm, preferably 200 to 1,500 nm, more preferably 200 to 1,000 nm, and particularly preferably 200 to 800 nm. The content of the inert particles A is 0.001 to 5% by weight, preferably 0.01 to 4% by weight, more preferably 0.03 to 3% by weight, particularly preferably 0, based on the layer A. 0.05 to 2.0% by weight. When the average particle diameter of the inert particles A is less than 100 nm or the content is less than 0.001% by weight (relative to the layer A), the film winding property and blocking resistance are poor. On the other hand, when the average particle diameter of the inert particles A exceeds 2,000 nm or the content exceeds 5% by weight (relative to the layer A), the shape transfer of the protrusions to the opposite surface (layer B surface) The protrusion of the protrusion from the bottom of the layer B makes the surface of the layer B rough and deteriorates the electromagnetic conversion characteristics.
[0022]
The inert particles A may be used alone or in combination with one or more other fine particles. When other fine particles are used in combination, the particles are particles having an average particle size smaller than the average particle size dA of the inert particles A. As such fine particles, for example, the second particles and the third particles, for example, colloidal silica, fine particles such as alumina having a crystal form such as α, γ, δ, θ can be preferably used. Of the particle types exemplified as the inert particles A having the average particle diameter dA, fine particles having a small average particle diameter can also be used as the second particles and the third particles.
[0023]
The average particle diameter of the fine particles is preferably in the range of 5 to 400 nm, more preferably 10 to 300 nm, particularly 30 to 250 nm, and 50 nm or more, further 100 nm or more, and particularly preferably 150 nm or more smaller than the average particle diameter dA. The content of the fine particles is preferably 0.005 to 1% by weight, more preferably 0.01 to 0.7% by weight, particularly preferably 0.05 to 0.5% by weight, based on the layer A. is there.
[0024]
The thermoplastic resin layer A in the present invention is an ester wax made of an aliphatic monocarboxylic acid and a polyhydric alcohol having 8 or more carbon atoms, which may be partially saponified. -10% by weight. This “optionally partially saponified ester wax” is used as an expression including ester wax and partially saponified ester wax, and may be referred to as (partially saponified) ester wax.
[0025]
The aliphatic monocarboxylic acid has 8 or more carbon atoms, preferably 8 to 34 carbon atoms. If the number of carbon atoms is 7 or less, the heat resistance of the (partially saponified) ester compound is insufficient, and the decomposition of the compound easily proceeds under heating conditions when dispersed in the thermoplastic resin A. Is appropriate.
[0026]
Examples of the aliphatic monocarboxylic acid having 8 or more carbon atoms include pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachin Examples thereof include acids, pehenic acid, lignoceric acid, serotic acid, montanic acid, melissic acid, hentriacontanoic acid, petroceric acid, oleic acid, erucic acid, linoleic acid, and acid mixtures containing these.
[0027]
The alcohol component of the (partially saponified) ester wax is a polyhydric alcohol having two or more hydroxyl groups. From the viewpoint of heat resistance, a polyhydric alcohol having 3 or more hydroxyl groups is preferred. When monoalcohol is used, the heat resistance of the (partially saponified) ester compound is insufficient and cannot be used as a wax in the present invention.
[0028]
Examples of the polyhydric alcohol having two hydroxyl groups include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, Preferred examples include 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, and polyethylene glycol. Preferred examples of the polyhydric alcohol having three or more hydroxyl groups include glycerin, erythritol, trait, pentaerythlit, arabit, xylit, tarit, sorbit, mannitol and the like.
[0029]
Examples of the ester wax obtained from the aliphatic monocarboxylic acid and the polyhydric alcohol include monoesters, diesters, triesters and the like, depending on the number of hydroxyl groups of the polyhydric alcohol. From the viewpoint of heat resistance, a diester is preferable to a monoester, and a triester is preferable to a diester. Specific examples of preferred ester waxes include sorbitan tristearate, pentaerythritol triphenate, glycerin tripalmitate, polyoxyethylene distearate and the like.
[0030]
The partially saponified ester wax comprising the aliphatic monocarboxylic acid and the polyhydric alcohol is obtained by partially esterifying a higher fatty acid having 8 or more carbon atoms with a polyhydric alcohol and then saponifying with a dihydric or higher metal hydroxide. Can be obtained. Specific examples include wax E, wax OP, wax O, wax OM, wax FL (all trade names manufactured by Hoechst Co., Ltd.) obtained by saponifying montanic acid diol ester with calcium hydroxide.
[0031]
The above (partially saponified) ester wax may be used alone or in combination of two or more.
[0032]
The thermoplastic resin layer A in the present invention contains the above (partially saponified) ester wax in an amount of 0.001 to 10% by weight, preferably 0.01 to 5% by weight, more preferably 0.05, based on the layer A. ˜2 wt%, particularly preferably 0.1 to 1 wt%. If this content is less than 0.001% by weight, the effect of improving blocking cannot be obtained. On the other hand, if it exceeds 10% by weight, a large amount of the wax component is transferred by bleed-out on the side opposite to the surface that comes into contact with the film when it is wound up on the roll in the film production process. Detrimental effects such as hindering the adhesion of the resin occur.
[0033]
Further, the water contact angle of the surface of the thermoplastic resin layer A in the present invention which is not in contact with the layer B is 70 to 90 °, preferably 71 to 89 °, more preferably 72 to 88 °, and particularly preferably 74 to 86. °. When the water contact angle is less than 70 °, the effect of improving blocking cannot be obtained. On the other hand, when the angle exceeds 90 °, problems such as application spots occur in the step of applying the backcoat layer.
[0034]
Centerline average roughness Ra of the outer surface of the thermoplastic resin layer A ^A Is preferably 2 to 20 nm, more preferably 3 to 15 nm, and particularly preferably 4 to 10 nm. This Ra ^A Is within this range, the effect on the slipperiness and abrasion resistance of the surface of the layer A is great.
[0035]
The laminated film of the present invention is provided with the thermoplastic resin layer B on the surface on which the magnetic layer is provided for the purpose of improving the handling properties during production and processing of the film and further improving various characteristics when used as a magnetic recording medium. .
[0036]
The thermoplastic resin layer B in the present invention may be substantially free of inert particles or may contain inert particles B.
[0037]
When the thermoplastic resin layer B does not substantially contain inert particles, it is preferable because it is excellent in electromagnetic conversion characteristics when used as a magnetic recording medium.
[0038]
On the other hand, from the viewpoint of improving running durability, the thermoplastic resin layer B preferably contains inert particles in a range that does not adversely affect electromagnetic conversion characteristics. Specifically, the inert spherical particles B having an average particle size of 30 to 200 nm are preferably contained in an amount of 0.001 to 0.2% by weight with respect to the layer B. Preferred inert particles B include spherical silica particles, spherical crosslinked silicone resin particles, and spherical crosslinked polyethylene resin particles. The average particle diameter dB of the inert particles B is 30 to 200 nm, more preferably 40 to 150 nm, and particularly preferably 50 to 100 nm. If the average particle size dB is less than 30 nm, the slipperiness of the film may be poor. On the other hand, if it exceeds 200 nm, the electromagnetic conversion characteristics of the magnetic recording medium may be poor. The inert particles B may be used alone or in combination of two or more.
[0039]
The content when the inert particles B are blended in the thermoplastic resin layer B is 0.001 to 0.2% by weight, more preferably 0.01 to 0.1% by weight, and particularly preferably 0. It is preferable that it is 02-0.05 mass%. If the content is less than 0.001% by weight, the slipperiness of the film may be poor, whereas if it exceeds 0.2% by weight, the electromagnetic conversion characteristics of the magnetic recording medium may be poor. Therefore, it is not preferable.
[0040]
The laminated thermoplastic resin film of the present invention has a coating layer C made of a binder resin, inert particles C, a surfactant, and a siloxane copolymer acrylic resin on the surface of the thermoplastic resin layer B that is not in contact with the thermoplastic resin layer A. Must be painted.
[0041]
Examples of the binder resin constituting the coating layer C in the present invention include alkyd resins, phenol resins, epoxy resins, amino resins, polyurethane resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, and the like. it can. Of these, water-soluble or water-dispersible resins from the viewpoints of adhesion to the thermoplastic resin layer B, particularly polyester layer B, protrusion retention, and slipperiness, and acrylic resins, polyester resins and acrylic resins A resin selected from the group consisting of polyester resins is preferred. These resins may be a single polymer or a copolymer, and may be a mixture. The content of the binder resin is preferably 20 to 90% by weight with respect to the layer C.
[0042]
The water-soluble or water-dispersible acrylic resin is, for example, an acrylic ester (as alcohol residues, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group etc. can be exemplified); methacrylic acid ester (alcohol residue is the same as above); 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2- Hydroxy-containing monomers such as hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc .; acrylamide, methacrylamide, N-methyl methacrylamide, N-methyl acrylamide, N-methylol acrylamide, N-methylol methacrylamide, N, N— Amide group-containing monomers such as methylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide and N-phenylacrylamide; amino group-containing monomers such as N, N-diethylaminoethyl acrylate and N, N-diethylaminoethyl methacrylate From one or more monomers such as epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, or such monomers, for example styrene sulfonic acid, vinyl sulfonic acid and their salts (eg sodium Monomers containing sulfonic acid groups such as salts, potassium salts, ammonium salts, etc. or salts thereof; crotonic acid, itaconic acid, acrylic acid, maleic acid, fumaric acid and their salts (eg, sodium Monomers containing carboxyl groups such as um salts, potassium salts, ammonium salts, etc .; monomers containing anhydrides such as maleic anhydride and itaconic anhydride; other vinyl isocyanates, allyl isocyanates, styrenes, vinylmethyls Combination of monomers such as ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride It is preferable that the component of the (meth) acrylic monomer such as an acrylic acid derivative or a methacrylic acid derivative is contained in an amount of 50 mol% or more, and particularly contains a methyl methacrylate component. What is good Good.
[0043]
The water-soluble or water-dispersible acrylic resin can be self-crosslinked with a functional group in the molecule, or can be crosslinked using a crosslinking agent such as a melamine resin or an epoxy compound.
[0044]
Examples of the acid component constituting the water-soluble or water-dispersible polyester resin include terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4 ′ -Diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, 5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p- Examples thereof include polyvalent carboxylic acids such as hydroxybenzoic acid and trimellitic acid monopotassium salt.
[0045]
Examples of the hydroxy compound component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, and p-xylylene. Glycols, ethylene oxide adducts of bisphenol A, diethylene glycol, triethylene glycol, polyethylene oxide glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropanoate, etc. A polyvalent hydroxy compound can be exemplified.
[0046]
A polyester resin can be produced from these compounds by a conventional method. From the viewpoint of producing an aqueous coating material, it is preferable to use an aqueous polyester resin containing a 5-sodium sulfoisophthalic acid component or a carboxylate group. Such a polyester resin can be a self-crosslinking type having a functional group in the molecule, or can be crosslinked using a curing agent such as a melamine resin or an epoxy resin.
[0047]
The acrylic-polyester resin in the present invention is used to include an acrylic-modified polyester resin and a polyester-modified acrylic resin. The acrylic resin component and the polyester resin component are bonded to each other, for example, graft type, block Includes types.
[0048]
The water-soluble or water-dispersible acrylic-polyester resin can be prepared, for example, by adding a radical initiator to both ends of the polyester resin to polymerize the acrylic monomer, or by adding a radical initiator to the side chain of the polyester resin. It can be produced by polymerizing an acrylic monomer or by adding a hydroxyl group to the side chain of an acrylic resin and reacting with a polyester having an isocyanate group or a carboxyl group at the terminal to form a comb polymer. As a component which comprises this acrylic-polyester resin, what was illustrated as a monomer which forms the said acrylic resin, and an acid component and a hydroxy compound component which comprise a polyester resin can be illustrated.
[0049]
Examples of the material of the inert particles C blended in the coating layer C in the present invention include polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, methyl methacrylate copolymer cross-linked product, polytetrafluoroethylene, and polyvinylidene. Any organic material such as fluoride, polyacrylonitrile, benzoguanamine resin, etc., inorganic material such as silica, alumina, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black, barium sulfate, etc. Good. Moreover, you may use as a core-shell type particle | grain of the multilayered structure comprised with the substance from which each property inside and outside differs.
[0050]
The average particle diameter of the inert particles C is preferably 5 to 100 nm, more preferably 10 to 50 nm. A uniform particle size distribution is preferred. When the average particle size is less than 5 nm, the slipping property and the abrasion resistance are deteriorated. On the other hand, when the average particle diameter exceeds 100 nm, the particles fall off from the layer C, and the abrasion resistance deteriorates. In addition, the spacing with the magnetic head increases, making it difficult to provide a high-density magnetic recording medium.
[0051]
The content of the inert particles C is preferably 0.5 to 30% by weight, more preferably 0.8 to 20% by weight, and particularly preferably 1.0 to 10% by weight with respect to the layer C. If the content is less than 0.5% by weight, the running durability of the magnetic recording medium is insufficient. On the other hand, if the content exceeds 30% by weight, the electromagnetic conversion characteristics are adversely affected.
[0052]
The film layer C in the present invention is characterized by containing a siloxane copolymer acrylic resin. The siloxane copolymer acrylic resin is a copolymer in which a siloxane component and an acrylic resin component are bonded to each other, and includes, for example, a graft type, a block type, and the like. For example, by adding a radical initiator to both ends of an acrylic resin to polymerize siloxane, attaching a hydroxyl group to the side chain of the siloxane, and reacting with an acrylic having an isocyanate group or a carboxyl group at the terminal to form a comb polymer, etc. Can be manufactured.
[0053]
As a component which comprises the said acrylic resin component, what was illustrated with the acrylic resin used for binder resin can be illustrated.
[0054]
As the siloxane component, as a chain component
[0055]
[Chemical 1]

[0056]
However, R ₁ Is a methyl group, a phenyl group or hydrogen, and R ₂ Is a methyl group, a phenyl group, hydrogen or a functional group (for example, an epoxy group, an amino group, a hydroxyl group), and n is a number from 100 to 7000.
And a polysiloxane compound having an epoxy group, an amino group, a hydroxyl group, and other functional end groups at the terminal. The siloxane component need not necessarily be a homopolymer, but may be a copolymer or a mixture of several homopolymers.
[0057]
The ratio of the acrylic resin component to the siloxane component is preferably 98: 2 to 50:50, more preferably 95: 5 to 60:40, by weight.
[0058]
The content of the siloxane copolymer acrylic resin in the coating layer C is preferably 1 to 30% by weight, more preferably 1 to 20% by weight. If the content is less than 1% by weight, the effect is insufficient and causes blocking and an increase in charging. On the other hand, if the content exceeds 30% by weight, the adhesion of the magnetic layer is deteriorated or wound into a roll. Occasionally, transfer to the contact surface occurs, or the contact roll becomes dirty when the film travels.
[0059]
Although it does not specifically limit about the surfactant which comprises the said film layer C, Nonionic surfactant, anionic surfactant, a cationic surfactant, etc. can be illustrated. These medium nonionic surfactants are preferred. Nonionic surfactants include those of ester type, ether type, and alkylphenol type. More specifically, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene monostearate, sorbitan stearate And polyoxyethylene sorbitan monostearate.
[0060]
Specific examples of these surfactants include, as polyoxyethylene alkylphenyl ether compounds, trade names “Nonion NS-230”, “NS-240”, “HS-220”, “manufactured by NOF Corporation”, “ "HS-240", trade names "Nonipol 200", "Nonipol 400", "Nonipol 500", "Octapol 4000" manufactured by Sanyo Chemical Co., Ltd .; polyoxyethylene alkyl ether compounds, manufactured by NOF Corporation "Nonion E-230", "K-220", "K-230"; polyoxyethylene alkyl ester compounds of higher fatty acids, trade names "Nonion S-15. 4 ”,“ S-40 ”, and the like.
[0061]
The content of the surfactant is preferably from 5 to 40% by weight, more preferably from 5 to 40% by weight, particularly from 10 to 40% by weight, especially from 12 to 30% by weight, based on the coating layer C.
[0062]
In the present invention, the surface roughness Ra of the coating layer C ^C Is preferably 0.1 to 2 nm, more preferably 0.5 to 1.5 nm. This surface roughness Ra ^C When the thickness exceeds 2 nm, the electromagnetic conversion characteristics deteriorate particularly when a metal thin film type magnetic recording medium is used. On the other hand, this Ra ^C If the thickness is less than 0.1 nm, the slipping property is extremely deteriorated and the running durability is insufficient, or it sticks to the magnetic head and causes tape squealing, so that it cannot be put to practical use.
[0063]
The total thickness of the laminated thermoplastic resin film in the present invention is usually 2.5 to 20 μm, preferably 3.0 to 10 μm, and more preferably 4.0 to 10 μm. The layer thickness of the thermoplastic resin layer A is preferably 1/2 or less, more preferably 1/3 or less, particularly preferably 1/4 or less of the total thickness of the laminated film. The thickness of the thermoplastic resin layer B is preferably 1/2 or more of the total thickness of the laminated film, more preferably 2/3 or more, and particularly preferably 3/4 or more. Furthermore, the thickness of the coating layer C is usually 1 to 100 nm, preferably 2 to 5 nm, more preferably 3 to 10 nm, and particularly preferably 3 to 8 nm.
[0064]
The laminated thermoplastic resin film in the present invention can be produced according to a method conventionally known or accumulated in the art. Among them, the laminated structure of the thermoplastic resin layer A and the thermoplastic resin layer B is preferably manufactured by a coextrusion method, and the coating layer C is preferably provided by a coating method.
[0065]
For example, in the case of a laminated biaxially oriented polyester film, first, a thermoplastic resin A in which inert particles A and (partially saponified) ester wax are uniformly dispersed and contained, and inert particles B as required are contained. Each of the thermoplastic resins B is subjected to high-accuracy filtration, and then laminated and composited in a molten state in the extrusion die or before the die (generally, the former is called a multi-manifold method and the latter is called a feed block method). A laminated structure with a thickness ratio is formed, and then coextruded into a film form at a temperature of melting point (Tm) to (Tm + 70) ° C. from the die, and rapidly solidified with a cooling roll of 30 to 90 ° C. to obtain an unstretched laminated film. Thereafter, the unstretched laminated film is uniaxially (longitudinal or transverse) uniaxially (longitudinal or transverse) at a temperature of (Tg-10) to (Tg + 70) ° C. (where Tg is the glass transition temperature of the polyester). The film is stretched at a magnification of 8.0 times, preferably at a magnification of 3.0 to 7.5 times, and then in a direction perpendicular to the stretching direction (when the first-stage stretching is the longitudinal direction, the second-stage stretching is transverse The film is stretched at a temperature of (Tg) to (Tg + 70) ° C. at a magnification of 2.5 to 8.0 times, preferably at a magnification of 3.0 to 7.5 times. At that time, if necessary, the film may be stretched again in the longitudinal direction and / or the transverse direction. That is, it is good to perform 2 steps | paragraphs, 3 steps | paragraphs, 4 steps | paragraphs, or multistage extending | stretching. The area stretching ratio is usually 9 times or more, preferably 12 to 35 times, and more preferably 15 to 30 times.
[0066]
Next, the biaxially stretched film is thermally fixed and crystallized at a temperature of (Tg + 70) to (Tm-10) ° C., for example, 180 to 250 ° C. in the case of a polyethylene terephthalate film. This gives excellent dimensional stability. The heat setting time is preferably 1 to 60 seconds.
[0067]
In the production of the laminated thermoplastic resin film, additives other than the above inert particles, for example, a stabilizer, a colorant, a specific resistance adjusting agent for a molten polymer, and the like may be added to the thermoplastic resins A and B as required. it can.
[0068]
In the present invention, the coating layer C is preferably applied to the thermoplastic resin layer B by a method of applying an aqueous coating liquid.
[0069]
The coating is preferably performed on the surface of the thermoplastic resin layer B before the final stretching treatment, and after coating, the film is preferably stretched at least in a uniaxial direction. The coating film is dried before or during the stretching. Among them, the coating is preferably performed on an unstretched laminated film or a longitudinal (uniaxial) stretched laminated film, particularly a longitudinal (uniaxial) stretched laminated film. Although it does not specifically limit as a coating method, For example, a roll coat method, a die coat method, etc. are mentioned preferably.
[0070]
The solid content concentration of the coating liquid, particularly the aqueous coating liquid, is preferably 0.2 to 8% by weight, more preferably 0.3 to 6% by weight, and particularly preferably 0.5 to 4% by weight. In the coating liquid (preferably aqueous coating liquid), other components, for example, a stabilizer, a dispersant, an ultraviolet absorber, a thickener and the like can be added within a range that does not hinder the effects of the present invention.
[0071]
In the present invention, in order to improve various performances such as head touch as a magnetic recording medium and running durability, and simultaneously achieve a thin film, the Young's modulus of the laminated film is 4. It is preferably 4 GPa or more and 5.9 GPa or more, more preferably 4.7 GPa or more and 6.7 GPa or more, particularly 5.4 GPa or more and 7.8 GPa or more, especially 5.5 GPa or more and 9.8 GPa or more.
[0072]
The crystallinity of the thermoplastic resin layers A and B is desirably 30 to 50% when the thermoplastic resin is polyethylene terephthalate and 28 to 38% when the thermoplastic resin is polyethylene-2,6-naphthalate. When both are below the lower limit, the heat shrinkage rate is increased. On the other hand, when the upper limit is exceeded, the abrasion resistance of the film is deteriorated, and white powder is liable to occur when sliding with the roll or guide pin surface.
[0073]
The laminated thermoplastic resin film of the present invention is preferably used as a support for a magnetic recording medium. Preferred embodiments in the case of using this laminated thermoplastic resin film as a support for a magnetic recording medium are as follows.
[0074]
The laminated thermoplastic resin film of the present invention is formed on the surface of the coating layer C by a method such as vacuum deposition, sputtering, or ion plating, and is made of iron, cobalt, chromium, or a ferromagnetic material composed of an alloy or oxide containing these as a main component. A metal thin film layer is formed, and a protective layer such as diamond-like carbon (DLC) and a fluorine-containing carboxylic acid-based lubricating layer are sequentially provided on the surface, if necessary, and a thermoplastic resin layer if necessary. By providing a backcoat layer on the surface opposite to the magnetic layer of A by a known method, the output in the short wavelength region, particularly excellent electromagnetic conversion characteristics such as S / N, C / N, dropout, A vapor deposition type magnetic recording medium for high density recording with a low error rate can be obtained. This vapor deposition type magnetic recording medium is extremely useful as a Hi8 for analog signal recording, a digital video cassette recorder (DVC) for digital signal recording, 8 mm data, and a magnetic tape medium for DDSIV.
[0075]
Further, the laminated thermoplastic resin film of the present invention is made of iron chloride or acicular fine magnetic powder (metal powder) containing polyvinyl chloride, vinyl chloride / vinyl acetate copolymer or the like on the surface of the coating layer C. Is uniformly dispersed in the binder, and the magnetic layer thickness is 1 μm or less, preferably 0.1 to 1 μm, and if necessary, the surface of the thermoplastic resin layer A opposite to the magnetic layer is publicly known. By providing a backcoat layer by this method, metal-coated magnetic recording for high-density recording, which has excellent output characteristics in the short wavelength region, electromagnetic conversion characteristics such as S / N, C / N, and low dropout and error rate. It can be a medium. If necessary, a nonmagnetic layer containing fine titanium oxide particles or the like as an underlayer of the metal powder-containing magnetic layer is dispersed on the surface of the coating layer C in an organic binder similar to that of the magnetic layer. It can also be set up. This metal-coated magnetic recording medium is an analog signal recording 8 mm video, Hi8, β cam SP, W-VHS, digital signal recording digital video cassette recorder (DVC), data 8 mm, DDSIV, digital β cam, D2. , D3, SX, etc. are very useful as magnetic tape media.
[0076]
Furthermore, the laminated thermoplastic resin film of the present invention is formed on the surface of the coating layer C by adding acicular fine magnetic powder such as iron oxide or chromium oxide or plate-like fine magnetic powder such as barium ferrite to polyvinyl chloride, It is uniformly dispersed in a binder such as a vinyl acetate copolymer, and is applied so that the magnetic layer thickness is 1 μm or less, preferably 0.1 to 1 μm. If necessary, it is opposite to the magnetic layer of the thermoplastic resin layer A. By providing a back coat layer on the side surface using a known method, high density recording with excellent output characteristics, especially S / N, C / N, etc. in the short wavelength region, and low dropout and error rate. It can be used as an oxide-coated magnetic recording medium. Further, if necessary, on the surface of the coating layer C, a nonmagnetic layer containing fine titanium oxide particles and the like as a base layer of the oxide powder-containing magnetic layer is dispersed in an organic binder similar to the magnetic layer, It can also be painted. This oxide-coated magnetic recording medium is useful as an oxide-coated magnetic recording medium for high-density recording, such as a QIC for data streamers for digital signal recording.
[0077]
The W-VHS is an analog HDTV signal recording VTR, and the DVC is applicable for digital HDTV signal recording. Therefore, the laminated thermoplastic resin film of the present invention can be said to be a very useful base film for these HDTV compatible VTR magnetic recording media.
[0078]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these Examples. In the examples and comparative examples, “parts” and “%” are parts by weight and% by weight unless otherwise specified. The physical property values and characteristics in the present invention are each measured and defined by the following methods.
[0079]
(1) Intrinsic viscosity
It calculated | required from the value measured at 35 degreeC in the orthochlorophenol solvent.
[0080]
(2) Average particle diameter (I) (average particle diameter: 60 nm or more)
Measurement is performed using “CP-50 Centrifuggle Particle Size Analyzer” manufactured by Shimadzu Corporation. A particle diameter “equivalent sphere diameter” corresponding to 50 mass percent is read from an integrated curve of particles of each particle diameter calculated based on the obtained centrifugal sedimentation curve and the abundance thereof, and this value is calculated as the average particle diameter (nm). ("Particle size measurement technology", published by Nikkan Kogyo Shimbun, 1975, pages 242-247).
[0081]
(3) Average particle diameter (II) (average particle diameter: less than 60 nm)
Particles having an average particle diameter of less than 60 nm that form small protrusions are measured using a light scattering method. That is, the average particle diameter of the particles having an “equivalent sphere diameter” of 50% of the total particles determined by the trade name “NICOMP MODEL 270 SUBMICRON PARTIC SIZER” manufactured by Nicomp Instruments Inc. The diameter (nm).
[0082]
(4) The thickness of the thermoplastic resin layers A and B and the thickness of the entire film
The thickness of the entire film is measured at 10 points randomly with a micrometer, and the average value is used. Regarding the layer thicknesses of the thermoplastic resin layers A and B, the layer thickness of the thin thermoplastic resin layer is measured by the method described below, and the layer thickness of the thick thermoplastic resin layer is less than the total thickness of the coating layer and the heat Subtract the layer thickness of the plastic resin layer. That is, using a secondary ion mass spectrometer (SIMS), the metal element (M +) caused by the highest concentration of particles in the film having a depth of 5,000 nm from the surface layer excluding the coating layer. The concentration ratio (M + / C +) of hydrocarbon (C +) to thermoplastic resin (polyester) was defined as the particle concentration, and the analysis was conducted in the thickness direction from the surface to a depth of 5,000 nm. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases. In the case of the present invention, the particle concentration may once rise to a stable value 1 and then rise to a stable value 2 or may monotonously decrease. Based on this distribution curve, the former has a depth that gives a particle concentration of (stable value 1 + stable value 2) / 2, and the latter has a depth at which the particle concentration is ½ of the stable value 1. The thickness (this depth is deeper than the depth that gives a stable value of 1) is the thickness (μm) of the thin thermoplastic resin layer.
[0083]
The measurement conditions are as follows.
(A) Measuring device
Secondary ion mass spectrometer (SIMS); manufactured by Perkin Elmer Inc., “6300”
(B) Measurement conditions
Primary ion species: O2 +
Primary ion acceleration voltage: 12KV
Primary ion current: 200 nA
Raster area: 400 μm
Analysis area: 30% gate
Measuring degree of vacuum: 6.0 × 10 −9 Torr
E-GUNN: 0.5KV-3.0A
In the case where organic polymer particles other than silicone resin are the most abundant particles in the range of 5,000 nm from the surface layer, it is difficult to measure by SIMS, so FT-IR (Fourier transform infrared spectroscopy while etching from the surface) ) Depending on the particle, a concentration distribution curve similar to the above is measured by XPS (X-ray photoelectric spectroscopy) or the like to determine the layer thickness (μm).
[0084]
(5) Thickness of coating layer C
A small piece of film is fixed and molded with an epoxy resin, and an ultrathin section (cut parallel to the film flow direction) having a thickness of about 600 angstroms is prepared with a microtome. This sample is observed with a transmission electron microscope (manufactured by Hitachi, Ltd .: Model H-800), and the boundary surface of the coating layer C is searched to determine the thickness (nm) of the coating layer.
[0085]
(6) Contact angle
Measured using a contact angle measuring device manufactured by Kyowa Science Co., Ltd. After the film sample is placed in an environment of temperature 25 ° C. and humidity 50% for 24 hours or more, 5 mg of distilled water is dropped on the film, and a photograph is taken 20 seconds after the horizontal direction. The angle formed by the tangent line between the film and the water droplet is defined as the contact angle (°).
[0086]
(7) Surface roughness of the film (centerline average roughness: Ra)
Centerline average roughness (Ra) is measured according to JIS-B601. In the present invention, a stylus type surface roughness meter (SURFCORDER SE, 30C) manufactured by Kosaka Laboratory Ltd. is used for measurement under the following conditions.
(A) Stylus tip radius: 2 μm
(B) Measurement pressure: 30 mg
(C) Cutoff: 0.08mm
(D) Measurement length: 8.0 mm
(E) How to summarize data: Repeat measurement 6 times for the same sample, remove one largest value, and use the remaining five data to determine the centerline average roughness (Ra) as an average value.
[0087]
(8) Young's modulus
Using a tensile tester manufactured by Toyo Baldwin Co., Ltd., trade name “Tensilon”, a sample film having a length of 300 mm and a width of 12.7 mm is 10% / min in a room adjusted to a temperature of 20 ° C. and a humidity of 50%. It pulls with a strain rate and calculates by the following Formula (V) using the first linear part of the tensile stress-strain curve.
[0088]
[Expression 1]
E = Δσ / Δε (V)
Here, E is a Young's modulus (Gpa), Δσ is a stress difference due to the original average cross-sectional area between two points on a straight line, and Δε is a strain difference between the same two points.
[0089]
(9) Blocking peel force
A roll-shaped film is sampled to a rectangle of 100 mm in the longitudinal direction and 200 mm in the width direction, and corona treatment is performed on the thermoplastic resin layer A (base film) side in an environment of room temperature 20 ± 2 ° C. and humidity 40 ± 5%. Apply.
The corona treatment is performed under the following conditions using a high-frequency power source of the trade name “CG-102” manufactured by Kasuga Electric Co., Ltd.
Current: 4.5A
Distance between electrodes: 1.0mm
Processing time: Processed by passing between electrodes at a speed of 1.2 m / min.
The treated surface of the film is immediately brought into contact with the surface opposite to the thermoplastic resin layer A of the film, and after aging for 17 hours in an environment at a temperature of 60 ° C. and a humidity of 80% at a pressure of 10 Mpa, the above tensile test is performed. Using a machine, the trade name “Tensilon”, the peel force per 100 mm width is obtained.
[0090]
(10) Windability
After optimizing the winding conditions at the time of slitting, 30 rolls are slit at a speed of 100 m / min with a width of 600 mm × 12,000 m, and a roll without bumps, protrusions or wrinkles is formed on the film surface after the slit. As a good product, the winding property is evaluated according to the following criteria.
◎: 28 or more non-defective rolls
○: Number of non-defective rolls 25 to 27
X: Number of good product rolls 16-24
XX: Number of non-defective rolls 15 or less
[0091]
(11) Back coat application suitability (workability)
In the following magnetic tape manufacturing process, the surface of the thermoplastic resin layer A after back coating is visually observed and evaluated according to the following criteria.
○: No coating spots or repellency in the back coat layer
X: Application spots or repellency is observed in the back coat layer
[0092]
(12) Manufacture of magnetic tape and evaluation of characteristics (electromagnetic conversion characteristics)
On the surface of the coating layer C of the laminated thermoplastic resin film, two layers (each layer thickness of about 0.1 μm) of a ferromagnetic thin film of 100% cobalt are formed to a thickness of 0.2 μm by vacuum deposition. A diamond-like carbon (DLC) film and a fluorine-containing carboxylic acid-based lubricating layer are sequentially provided on the surface of the formed ferromagnetic thin film, and a backcoat layer is provided on the surface of the thermoplastic resin layer A by a known method. Thereafter, it is slit to 8 mm width and loaded onto a commercially available 8 mm video cassette. Subsequently, the characteristic (C / N) of a tape is measured using the following commercially available apparatus.
Equipment used: 8 mm video tape recorder, manufactured by Sony Corporation, trade name “EDV-6000”
C / N measurement: Noise meter, manufactured by Shibasoku Co., Ltd.
A signal with a recording wavelength of 0.5 μm (frequency of about 7.4 MHz) is recorded, and the ratio of the 6.4 MHz and 7.4 MHz values of the reproduced signal is defined as the C / N of the tape, and the C of the 8 mm video vapor-deposited tape for video is commercially available. / N is set to 0 dB, and evaluation is performed with a relative value.
[0093]
(13) Preparation of inert particles A and B
As the inert particles A, the following are used.
True spherical silica; average particle size 600nm
θ-type alumina; average particle size 60 nm
Silicone; average particle size 500 nm
Cross-linked polystyrene; average particle size 800nm
The following are used as the inert particles B.
Spherical silica; average particle size 60 nm
[0094]
(14) Preparation of (partially saponified) ester wax
The following are used as (partially saponified) ester waxes comprising an aliphatic monocarboxylic acid having 8 or more carbon atoms and a polyhydric alcohol.
(A-1): sorbitan tristearate (melting point 55 ° C.)
(A-2): Montanic acid diol ester saponified with calcium hydroxide, manufactured by Hoechst Co., Ltd., trade name “wax E” (melting point: 86 ° C.)
(A-3): Glycerol tripalmitate
[0095]
[Example 1]
Resin dimethyl terephthalate and ethylene glycol, manganese acetate as the transesterification catalyst, titanium trimellitic acid as the polymerization catalyst, phosphorous acid as the stabilizer, and spherical silica with an average particle diameter of 60 nm as the lubricant (inert particles B) 0.03% was added and polymerized by a conventional method to obtain polyethylene terephthalate (resin B1) for thermoplastic resin layer B having an intrinsic viscosity of 0.60.
[0096]
Further, in the same manner as described above, as the lubricant (inert particles A), true spherical silica having an average particle diameter of 600 nm and θ-type alumina having an average particle diameter of 60 nm were added to the resin in an amount of 0.12% and 0.2%, respectively. The resultant was added and polymerized by a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60.
[0097]
The obtained polyethylene terephthalate (99.7%) is coated with 0.3% of sorbitan tristearate (a-1) powder and kneaded with a vented biaxial ruder, and a thermoplastic resin layer A having an intrinsic viscosity of 0.59. Polyethylene terephthalate (resin A1) was obtained.
[0098]
The obtained resin A1 and resin B1 were each dried at 170 ° C. for 3 hours, then supplied to two extruders, melted at a melting temperature of 280 to 300 ° C., and highly accurate with a steel wire filter having an average opening of 11 μm. After filtration, using a multi-manifold coextrusion die, the resin layer B was laminated on one side of the resin layer A and rapidly cooled to obtain a laminated unstretched film having a thickness of 89 μm.
[0099]
The obtained laminated unstretched film was preheated, stretched 3.3 times at a film temperature of 100 ° C. between low-speed and high-speed rolls, and rapidly cooled to obtain a longitudinally stretched film. Next, an aqueous coating liquid (total solid concentration: 1.0%) having the following composition (in terms of solid content) was applied as a coating layer C on the layer B surface side of the longitudinally stretched film by the kiss coating method.
[0100]

[0101]
Then, it supplied to the stenter and extended | stretched 4.2 times in the horizontal direction at 110 degreeC. The obtained biaxially stretched film was heat-fixed with hot air at 220 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a total thickness of 6.4 μm and a base layer (thermoplastic resin layer A) thickness of 1.0 μm. The thickness of the thermoplastic resin layers A and B of this laminated biaxially oriented film was adjusted by the discharge amount of two extruders. The Young's modulus of this laminated film was 4.9 GPa in the vertical direction and 6.9 GPa in the horizontal direction. Table 1 shows the other characteristics of the laminated biaxially oriented film and the characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0102]
[Example 2]
The type of inert particles A, the average particle size and the amount added, and the type and amount of (partially saponified) ester wax contained in the thermoplastic resin layer A are changed as shown in Table 1, and the thermoplastic resin B is changed. A laminated biaxially oriented polyester film was obtained in the same manner as in Example 1 except that no particles were contained. Table 1 shows the characteristics of the obtained laminated biaxially oriented film and the characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0103]
[Example 3]
Example 1 except that the kind of inert particles A contained in the thermoplastic resin layer A, the average particle diameter and the addition amount, and the kind and addition amount of (partially esterified) ester wax are changed as shown in Table 1. Similarly, a laminated biaxially oriented polyester film was obtained. Table 1 shows the characteristics of the obtained laminated biaxially oriented film and the characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0104]
[Example 4]
The kind of inert particles A to be contained in the thermoplastic resin layer A, the average particle diameter and the added amount, and the kind and the added amount of (partially saponified) ester wax are changed as shown in Table 1, and 2 instead of dimethyl terephthalate. Polyethylene-2,6-naphthalate (PEN) (resins A2 and B2) for thermoplastic resin layers A and B was obtained in the same manner as in Example 1 except that the same molar amount of dimethyl 6-naphthalenedicarboxylate was used. It was.
[0105]
After the resins A2 and B2 were dried at 170 ° C. for 6 hours, respectively, the thickness of each layer was adjusted in the same manner as in Example 1 to obtain a laminated unstretched film having a thickness of 89 μm.
[0106]
The obtained laminated unstretched film was preheated, further stretched 3.6 times at a film temperature of 135 ° C. between low speed and high speed rolls, and rapidly cooled to obtain a longitudinally stretched film. Next, an aqueous coating liquid (total solid concentration: 1.0%) having the composition shown in Table 1 (in terms of solid content) was applied as the coating layer C on the layer B surface side of the longitudinally stretched film in the same manner as in Example 1.
[0107]
Then, it supplied to the stenter and extended | stretched 5.7 times in the horizontal direction at 155 degreeC. The obtained biaxially stretched film was heat-fixed with hot air at 200 ° C. for 4 seconds to obtain a laminated biaxially oriented polyester film having a total thickness of 4.4 μm and a base layer (thermoplastic resin layer A) thickness of 0.6 μm. The thicknesses of the thermoplastic resin layers A and B of the laminated biaxially oriented film were adjusted by the discharge amounts of two extruders. The Young's modulus of this film was 5.4 GPa in the vertical direction and 10.3 GPa in the horizontal direction. Table 1 shows the other characteristics of the laminated film and the characteristics of the ferromagnetic thin film deposition type magnetic tape using the film.
[0108]
[Example 5]
A laminated biaxially oriented polyester film was obtained in the same manner as in Example 4 except that the thermoplastic resin B did not contain particles. Table 1 shows the characteristics of the obtained laminated biaxially oriented film and the characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0109]
[Comparative Example 1]
A laminated biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the thermoplastic resin layer A did not contain (partially saponified) ester wax and the coating layer C was not provided. When the obtained laminated biaxially oriented film was measured for the blocking peel force, the film was in close contact, and it was torn when trying to peel it off. Table 1 shows other characteristics and characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0110]
[Comparative Example 2]
A laminated biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the amount of sorbitan tristearate (a-1) added was 12%. When the obtained laminated biaxially oriented film was applied to the back coat in the magnetic tape manufacturing process, repelling occurred and normal application could not be performed. Table 1 shows other characteristics and characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0111]
[Comparative Example 3]
A laminated biaxially oriented polyester film was obtained in the same manner as in Example 4 except that the thermoplastic resin layer A did not contain inert particles and the coating layer C was not provided. When the obtained laminated biaxially oriented film was measured for the blocking peel force, the film was in close contact with each other, and measurement was impossible. Table 1 shows other characteristics and characteristics of the ferromagnetic thin film vapor deposition type magnetic tape using this film.
[0112]
[Table 1]

[0113]
As is clear from Table 1, the laminated biaxially oriented polyester film according to the present invention is very flat on one side, exhibits excellent electromagnetic conversion characteristics, has very good winding properties, and has good blocking resistance. It is. On the other hand, those not satisfying the requirements of the present invention cannot satisfy these characteristics at the same time.
[0114]
【The invention's effect】
According to the present invention, it is possible to provide a laminated thermoplastic resin film which is excellent in blocking resistance, winding property and processability and excellent in electromagnetic conversion characteristics when used as a support for a metal-deposited thin film magnetic recording medium. it can.

Claims (11)

A thermoplastic resin layer A is laminated on one surface of the thermoplastic resin layer B, and a coating layer C made of a binder resin, inert particles C, a surfactant and a siloxane copolymer acrylic resin is applied on the other surface. The thermoplastic resin layer A comprises 0.001 to 5% by weight (based on the layer A) of inert particles A having an average particle size of 100 to 2,000 nm and 8 or more carbon atoms. An ester wax composed of an aliphatic monocarboxylic acid and a polyhydric alcohol, which may be partially saponified, contains 0.001 to 10% by weight (based on the layer A), and the heat of the thermoplastic resin layer A A laminated thermoplastic resin film, wherein a water contact angle of a surface not in contact with the plastic resin layer B is 70 to 90 °. The laminate according to claim 1, wherein the binder resin as a component constituting the film layer C is a water-soluble or water-dispersible resin and is at least one selected from the group consisting of an acrylic resin, a polyester resin, and an acrylic-polyester resin. Thermoplastic resin film. The average particle diameter of the inert particles C as components constituting the coating layer C is 5 to 100 nm, and the content of the particles C is 0.5 to 30% by weight (relative to the layer C). 2. The laminated thermoplastic resin film according to 2. 4. The laminated thermoplastic resin film according to claim 1, wherein the content of the siloxane copolymer acrylic resin as a component constituting the film layer C is 1 to 30% by weight (relative to the layer C). Laminated thermoplastic resin film according to any one of claims 1 to 4 the center line average roughness Ra ^C of the outer surface of the coating layer C is 0.1 to 2 nm. Laminated thermoplastic resin film according to claim 1 center line average roughness Ra ^A of the outer surface of the thermoplastic resin layer A is a 2 to 20 nm. The laminated thermoplastic resin film according to claim 1, wherein the thermoplastic resin layer B contains substantially no inert particles. The laminated thermoplastic resin film according to claim 1, wherein the thermoplastic resin layer B contains 0.001 to 0.2 wt% (based on the layer B) of inert spherical particles B having an average particle size of 30 to 200 nm. The laminated thermoplastic resin film according to claim 1, 6, 7 or 8, wherein the thermoplastic resin constituting the layer A and the layer B is polyethylene terephthalate. The laminated thermoplastic resin film according to claim 1, 6, 7 or 8, wherein the thermoplastic resins constituting the layer A and the layer B are polyethylene-2,6-naphthalate, respectively. The laminated thermoplastic resin film according to any one of claims 1 to 10, wherein the laminated thermoplastic resin film is used as a support for a magnetic recording medium.