JP3973297B2 - Copolyester and film using the same - Google Patents

Description

【００１４】
ここで、Ａは炭素数６〜１８の芳香環を含む基であり、Ｙ¹およびＹ²は同一もしくは異なり、水素原子またはエステル形成性官能基であり(但し、Ｙ¹およびＹ²が同時に水素原子であることはない)、そしてｎは１または２であり、Ｒ¹、Ｒ²、Ｒ³およびＲ⁴は同一もしくは異なり、炭素数１〜１８のアルキル基、ベンジル基または炭素数６〜１２のアリール基である。
【００１５】
上記式において、Ａは炭素数６〜１８の芳香環を含む基であり、例えばベンゼン骨格、ナフタレン骨格あるいはビフェニル骨格を含む基を好ましい例として挙げることができる。かかる芳香環はＹ¹、Ｙ²およびスルホン酸４級ホスホニウム塩基のほかに例えば炭素数１〜１２のアルキル基等で置換されていても良い。
【００１６】
また、Ｙ¹およびＹ²は水素原子またはエステル形成性官能基であり、例えば−ＣＯＯＨ、ーＣＯＯＲ’、−ＯＣＯＲ’、−(ＣＨ₂)_nＯＨ、−(ＯＣＨ₂)_nＯＨ等を好ましく挙げることができる。これらの基中、Ｒ’は炭素数１〜４の低級アルキル基またはフェニル基であり、ｎは１〜１０の整数である。Ｒ’としてはメチル、エチル、ｎ−プロピル、ｉｓｏ−プロピル、ｎ−ブチル等を好ましい例として挙げることができる。また、スルホン酸４級ホスホニウム塩基の部分を構成する基Ｒ¹、Ｒ²、Ｒ³およびＲ⁴は、同一もしくは互いに異なり、炭素数１〜１８のアルキル基としてはメチル、エチル、プロピル、ブチル、ドデシル、ステアリル等を挙げることができる。炭素数６〜１２のアリール基としては、例えばフェニル、ナフチル、ビフェニル等を挙げることができる。
【００１７】
上記スルホン酸４級ホスホニウム塩の好ましい具体例としては、3,5-ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩、3,5-ジカルボキシベンゼンスルホン酸エチルトリブチルホスホニウム塩、3,5-ジカルボキシベンゼンスルホン酸ベンジルトリブチルホスホニウム塩、3,5-ジカルボキシベンゼンスルホン酸フェニルトリブチルホスホニウム塩、3,5-ジカルボキシベンゼンスルホン酸テトラフェニルホスホニウム塩、3,5-ジカルボキシベンゼンスルホン酸ブチルトリフェニルホスホニウム塩、3,5-ジカルボメトキシベンゼンスルホン酸テトラブチルホスホニウム塩、3,5-ジカルボメトキシベンゼンスルホン酸エチルトリブチルホスホニウム塩、3,5-ジカルボメトキシベンゼンスルホン酸ベンジルトリブチルホスホニウム塩、3,5-ジカルボメトキシベンゼンスルホン酸フェニルトリブチルホスホニウム塩、3,5-ジ（βーヒドロキシエトキシカルボニル）ベンゼンスルホン酸テトラブチルホスホニウム塩、3,5-ジ（βーヒドロキシエトキシカルボニル）ベンゼンスルホン酸テトラフェニルホスホニウム塩、3,-ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩、3-ジカルボキシベンゼンスルホン酸テトラフェニルホスホニウム塩、3-ジ（β-ヒドロキシエトキシカルボニル）ベンゼンスルホン酸テトラブチルホスホニウム塩、3-ジ（β-ヒドロキシエトキシカルボニル）ベンゼンスルホン酸テトラフェニルホスホニウム塩、４-ジ（β-ヒドロキシエトキシカルボニル）ベンゼンスルホン酸テトラブチルホスホニウム塩、ビスフェノールＡ-３，３ジ（スルホン酸テトラブチルホスホニウム塩）、２，６-ジカルボキシナフタレン-４-スルホン酸テトラブチルホスホニウム塩等を挙げる事ができる。上記スルホン酸４級ホスホニウム塩は一種のみを単独で用いても、２種以上を併用しても良い。
【００１８】
本発明における共重合ポリエステルはエチレンテレフタレートを主たる繰り返し単位とし、共重合成分としては酸成分でもアルコール成分でも良い。共重合酸成分としては例えば、アジピン酸、アゼライン酸、セバシン酸、デカンジカルボン酸等の如き脂肪族ジカルボン酸、イソフタル酸、フタル酸、２，６−ナフタレンジカルボン酸、２，７−ナフタレンジカルボン酸、１，５−ナフタレンジカルボン酸の如き芳香族ジカルボン酸などを好ましく挙げることができる。一方、共重合アルコール成分としては例えば、プロピレングリコール、ネオペンチルグリコール、ブタンジオール、ペンタンジオール、ヘキサンジオール等のポリアルキレングリコールなどを好ましく挙げることができる。これらは、単独または２種以上を使用することができる。
【００１９】
共重合成分の割合は、結果としてポリマー融点が２０５〜２５３℃の範囲にあればよい。ポリマー融点が２０５℃未満の場合には、共重合によるポリマー結晶性の低下により、フィルム製膜前の乾燥工程でポリマーチップ間で融着を起こしフィルムの生産性が大きく低下してしまう。一方、ポリマー融点が２５３℃を超えると、静電ワイヤーの汚れおよび押出し口金面への昇華物付着を抑制することができない。かかる共重合ポリエステルは実質的に線状ポリマーであって、フィルム形成性、特に溶融状態によるフィルム形成性を有する。
【００２０】
また、前記共重合ポリエステルには実質的に線状である範囲の量であり、且つ本発明の効果を損なわないかぎり、例えば全酸成分に対し２モル％以下の量で３官能以上のポリカルボン酸またはポリヒドロキシ化合物、例えばトリメリット酸、ペンタエリスリトール等を共重合させることができる。
【００２１】
さらに、本発明における共重合ポリエステルには表面平坦性、乾熱劣化性を損なわない程度であれば、例えば顔料、染料、酸化防止剤、光安定剤、遮光剤の如き添加剤を必要に応じて含有させることができる。
【００２２】
本発明において、前記スルホン酸４級ホスホニウム塩は全二官能性カルボン酸成分の０．１〜４５ｍｍｏｌ％を占め、共重合ポリエステルの溶融時の交流体積抵抗率は２．０×１０⁸Ωｃｍ以下を示し、比較的速く回転する冷却ドラム上にも密着するに十分な電荷量を付与でき、本発明の目的のひとつである製膜速度の向上を達成することができる。
【００２３】
本発明における共重合ポリエステルは公知の方法によって製造できる。例えば、便宜のためにイソフタル酸共重合ポリエチレンテレフタレートを例に挙げて説明すれば、通常、テレフタル酸およびイソフタル酸とエチレングリコールとを直接エステル化反応させるか、テレフタル酸ジメチルおよびイソフタル酸ジメチルの如きテレフタル酸の低級アルキルエステルとエチレングリコールとをエステル交換反応させるか又はテレフタル酸およびイソフタル酸とエチレンオキサイドとを付加反応させるなどしてテレフタル酸のグリコールエステル及び／又はその低重合体を生成させる第一段階の反応と、第一段階の反応生成物を減圧下加熱して所望の重合度になるまで重縮合させる第二段階の反応によって製造される。この際、触媒等の添加剤は任意に使用することができる。上記スルホン酸４級ホスホニウム塩をかかる共重合ポリエステルに含有させるには、前述した共重合ポリエステルの合成が完了するまでの任意の段階で、反応系中に添加してもよいし、前述の共重合ポリエステルの合成が完了し、これとスルホン酸４級ホスホニウム塩を例えばベント付き二軸混練押出し機にフィードして含有させてもよい。後者の場合、本発明者の知見ではスルホン酸４級ホスホニウム塩の反応は十分に進ませることが出来、簡便で十分な効果が発現するので好ましい。
【００２４】
本発明の共重合ポリエステルは５０％エタノール溶液中に２５０°Ｆ、２時間浸漬した後に検出されるスルホン酸４級ホスホニウム塩が１ｐｐｍ以下であることが好ましい。検出されるスルホン酸４級ホスホニウム塩が１ｐｐｍを超えると、フィルムを食品包装用途等に用いる際に好ましくない。スルホン酸４級ホスホニウム塩の検出量を１ｐｐｍ以下にするには、該共重合ポリエステル製造の際に、スルホン酸４級ホスホニウム塩を、共重合ポリエステル樹脂の合成段階あるいは共重合ポリエステル樹脂に添加後、少なくとも３分以上、系内が２４０℃以上となるような添加時期を選んでスルホン酸４級ホスホニウム塩を添加すればよい。
【００２５】
本発明において共重合ポリエステルをフィルムへと成形加工する方法は、例えば該共重合ポリエステルを融点（Ｔｍ）ないし（Ｔｍ＋７０）℃の温度で回転冷却ドラム上に押出し急冷して例えば２０〜５００μの未延伸フィルムとし、ついで該未延伸フィルムを一軸方向(縦方向または横方向)に（Ｔｇ−１０）〜（Ｔｇ＋７０）℃の温度(但しＴｇ；ポリエステルのガラス転移温度)で２．５〜５．０倍の倍率で延伸し、続いて上記延伸方向と直角方向に（Ｔｇ）〜（Ｔｇ＋７０）℃の温度で２．５〜５．０倍の倍率で延伸することで二軸延伸フィルムを得ることができる。延伸方法は逐次二軸延伸、同時二軸延伸のいずれでもよい。更に得られたフィルムは（Ｔｇ＋７０）〜（Ｔｍ）℃の温度で熱固定することができる。熱固定時間は例えば１〜３０秒である。
【００２６】
【実施例】
以下、本発明を実施例を挙げて更に詳細に説明するが、本発明はその要旨を越えない限り、以下の実施例によって限定されるものではない。なお、実施例での各特性値の測定は次の方法による。また、部は重量部を意味する。
【００２７】
（１）溶融ポリマーの交流体積抵抗率
測定しようとするポリマー中に一対の電極を挿入した容器を加熱媒体中に浸し、ポリマーを２８５℃の温度に加熱溶融しこの温度に保つ。ポリマー中に挿入した電極に外部より接続した交流電源から１００Ｖ−５０Ｈｚの電圧を印加する。この時の電流計と電圧計の指示値および電極面積、電極間距離より計算により交流体積抵抗率を求める。
【００２８】
（２）静電キャスト性
ポリマーをフィルム状に溶融押出しする口金の近くで、且つ押出したフィルムの上部に設置した電極により、冷却ドラムとの間に６ｋＶの電圧を印加してキャスティングする際、表面欠点を生じず、厚みの均一性を低下する事なく安定に製膜できる最大の冷却ドラムの速度を求める。冷却ドラムの最大速度により以下の如くランク付けして評価する。
ランクＡ：冷却ドラムの速度が７０ｍ／分以上で安定に製膜できる。
ランクＢ：冷却ドラムの速度が６０ｍ／分以上、７０ｍ／分未満で安定に製膜できる。
ランクＣ：冷却ドラムの速度が５５ｍ／分以上、６０ｍ／分未満で安定に製膜できる。
ランクＤ：冷却ドラムの速度が５５ｍ／分未満でしか安定に製膜できない。
【００２９】
（３）静電ワイヤーの汚れ性
上記（２）の静電キャスト性テストにおいてテスト時間を延長し、静電ワイヤーへの汚れに基づく静電ワイヤーの電流値の低下率を調べる。テスト開始時の電流値とテスト終了時の電流値を読み取り、その差をテスト時間で除して単位時間当たりの電流低下率を求める。その値により次の如くランク付けして評価する。
ランクＡ：電流低下率１％／ｈｒ未満
ランクＢ：電流低下率１％／ｈｒ以上５％／ｈｒ未満
ランクＣ：電流低下率５％／ｈｒ以上１０％／ｈｒ未満
ランクＤ：電流低下率１０％／ｈｒ以上
ランクＡならば実用上特に問題はない。ランクＢ、Ｃでは静電ワイヤーの交換頻度が多くなり、生産効率の点からやや不利となる。ランクＤでは実用に供することはできない。
【００３０】
（４）押出し口金への昇華物付着
押出し口金への昇華物付着が起こると、口金より押出される溶融ポリマーが付着物に接触し、フィルム表面に筋が発生する。この筋の発生の有無を目視観察により判定する方法であって、溶融ポリマーを押出し口金より押出し、８時間経過後に、回転冷却ドラムに密着させて冷却して、実質的に非晶状態のフィルムを得、このフィルムを目視観察する。８時間経過後に筋が認められる場合には、押出し口金に付着した昇華物を除去する必要があり生産性に劣る。尚、溶融ポリマー温度は昇華物付着抑制のため、溶融ポリマーの押出しに支障をきたさない範囲で最も低温となりうる温度に設定する。
【００３１】
（５）フィルム表面欠点
共重合ポリエステルの重合から押出し工程で副生する粒子状異物の評価であって、溶融ポリマー押出し、回転冷却ドラムに密着させて冷却して、実質的に非晶状態のフィルムを得、その後、これを縦方向に３．６倍、横方向に３．９倍の延伸を行って、厚さ１５μｍのフィルムを製造する。このフィルムを位相差顕微鏡を用いて観察し、画像解析装置ルーゼックス５００（日本レギュレーター製）で顕微画像内の最大長が１０μｍ以上の粒子数をカウントする。この粒子数が１０個／ｃｍ²以下の物ものを実用に供する事ができる。尚、溶融ポリマー温度は昇華物付着抑制のため、溶融ポリマーの押出しに支障をきたさない範囲で最も低温となりうる温度に設定する。
【００３２】
（６）乾燥工程でのポリマーチップ間での融着
ポリマーを１６０℃で４時間乾燥後に発生するポリマーチップ間での融着物の最大径を測定し以下の如くランク付けして評価する。
ランクＡ：融着物の最大径が５ｍｍ未満
ランクＢ：融着物の最大径が５ｍｍ以上、１０ｍｍ未満
ランクＣ：融着物の最大径が１０ｍｍ以上２０ｍｍ未満
ランクＤ：融着物の最大径が２０ｍｍ以上
ランクＡ、Ｂならば実用上特に問題はない。ランクＣではチップが押出し機に供給された際、希に吐出変動を起こすため生産性にやや劣る。ランクＤでは実用に供する事はできない。
【００３３】
（７）エタノール溶液処理によるスルホン酸４級ホスホニウム塩の溶出量
フィルムの片面の表面積が２５inch²になるように採取し、これを５０％エタノール溶液中に浸漬し、オートクレーブ内で２５０°Ｆで２時間処理し、得られた抽出液をホットプレート上で蒸発乾固し、残留物にメタノールを加えこれを高速液体クロマトグラフ（島津ＬＣ−１０ＡＤ）により測定し、スルホン酸４級ホスホニウム塩の溶出量を定量する。
【００３４】
［実施例１］
テレフタル酸ジメチル８８部とイソフタル酸ジメチル１２部とエチレングリコール７０部の混合物に酢酸マンガン・４水塩０．０３８部を添加し、１５０℃から２４０℃に徐々に昇温しながらエステル交換反応を行った。途中反応温度が１７０℃に達した時点で三酸化アンチモン０．０４部を添加し、さらに平均粒径０．６μｍの球状シリカ０．２部を添加し、次いで２２０℃に達した時点で３，５−ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩０．０３４部とエチレングリコール０．１２４部との混合物を４０℃に加熱した溶液として添加した。引き続きエステル交換反応を行い、エステル交換反応終了後、リン酸トリメチルをエチレングリコール中で１３５℃、５時間、１．１〜１．６ｋｇ／ｃｍ２の加圧下で加熱処理した溶液（リン酸トリメチル換算量で０．０４９部）を添加した。その後反応生成物を重合容器に移し、２９０℃まで昇温し、０．２ｍｍＨｇ以下の高真空にて重縮合反応を行って、固有粘度０．６０である共重合ポリエステルを得た。この共重合ポリエステル樹脂組成物の２８５℃における交流体積抵抗率の値は２．５×１０⁷Ω・ｃｍであった。
【００３５】
この共重合ポリエステルのペレットを１７０℃で３時間乾燥後、押出し機ホッパーに供給し、溶融温度２８０℃で１ｍｍのスリット状ダイを通して２００μｍに溶融押出しし、線上電極を用いて表面温度２０℃の回転冷却ドラム上に密着固化した。この時、冷却ドラムの速度を徐々に高めて、密着不良に起因する表面欠点を生じる事なく、安定に冷却フィルムが製造できる最高のキャスティング速度は１００ｍ／分であった。次いでこの未延伸フィルムを７５℃にて予熱し、低速、高速のロール間で１５ｍｍ上方より８５０℃の表面温度のＩＲヒーター１本にて加熱し縦方向に３．６倍に延伸し、続いてこの一軸延伸フィルムをステンターに供給し１０５℃にて横方向に３．９倍に延伸し、これを１９０℃の温度で３秒間熱固定処理し、厚み１４μｍの二軸延伸フィルムを得た。このフィルムの特性を表１、２に示す。
【００３６】
［実施例２、３、比較例１、２］
３，５ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩の添加量を表１に示す如く変更する、あるいは３，５ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩を添加しない以外は、実施例１と同様に行った。この結果を表１、２に示す。
【００３７】
［実施例４］
３，５ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩のかわりに、３，５ジカルボキシベンゼンスルホン酸テトラフェニルホスホニウムを使用する以外は、実施例１と同様に行った。この結果を表１、２に示す。
【００３８】
［実施例５、６および比較例３、４］
共重合成分として使用するイソフタル酸の量を表１に示す如く変更する事以外は、実施例１と同様に行った。ただし、比較例３の押出し温度は２８５℃とした。この結果を表１、２に示す。
【００３９】
［実施例７］
共重合成分としてアジピン酸を６ｍｏｌ％使用する以外は、実施例１と同様に行った。この結果を表１、２に示す。
【００４０】
［実施例８］
実施例１において３，５−ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩を添加することなく、共重合ポリエステル樹脂の合成反応を完了させこれをチップ化した。ついで、このチップをベント付き二軸混練押出し機に２０ｋｇ／ｈｒの割合で供給し、これに対して１２ｍｍｏｌ％の割合となるように３，５−ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩を供給した。この際、ベント孔の真空度を１ｍｍＨｇに設定し、シリンダ温度を２８５℃にして溶融混練し、共重合ポリエステルを得る以外は、実施例１と同様に行った。この結果を表１、２に示す。
【００４１】
［実施例９］
テレフタル酸／イソフタル酸＝８８／１２のビス−β−ヒドロキシエチルエステル１００部とテレフタル酸５７部とイソフタル酸８部にエチレングリコール２９部と３，５−ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩０．０３１部の混合物を２１０〜２３０℃の温度でエステル化反応を行った。反応により生成する水の留出量が１３部となった時点で反応を終了とし、反応生成物１００部あたり０．０２７部の三酸化アンチモン、リン酸トリメチルを１３５℃、５時間加熱処理した溶液（リン酸トリメチル換算量で０．００２部）を添加した。その後反応生成物を重合容器に移し、２９０℃まで昇温し０．２ｍｍＨｇ以下の高真空にて重縮合反応を行って共重合ポリエステルを得た。このポリエステルを用いて実施例１と同様に特性の評価を行った。この結果を表１、２に示す。
【００４２】
［実施例１０］
テレフタル酸ジメチル(ＤＭＴ)８８部／ｈｒ、イソフタル酸ジメチル(ＤＭＩ)１２部／ｈｒおよびエチレングリコール７０部／ｈｒを酢酸マンガン０．０５ｍｏｌ％／(ＤＭＴ＋ＤＭＩ)、酢酸亜鉛０．０１ｍｏｌ％／(ＤＭＴ＋ＤＭＩ)の触媒と共に連続式エステル交換反応槽に連続的に供給し、メタノールを留出させながら１５０〜２５０℃に加熱してエステル交換反応させた。次いで得られたエステル交換反応生成物に、亜リン酸０．１ｍｏｌ％／(ＤＭＴ＋ＤＭＩ)、３，５−ジカルボキシベンゼンスルホン酸テトラブチルホスホニウム塩０．０１ｍｏｌ％／(ＤＭＴ＋ＤＭＩ)、さらに重合触媒として三酸化アンチモン０．０３ｍｏｌ％／(ＤＭＴ＋ＤＭＩ)を加えた後、初期重合槽に連続的にフィードし５０ｍｍＨｇ、２６０℃で１時間反応させた。更にこれを溶融状態のまま中間重合槽で５ｍｍＨｇ、２８０℃で二時間反応させ、次にこれを最終重合槽へ溶融状態のまま連続的にフィードし１ｍｍＨｇ、２９０℃で１０分間反応させ、共重合ポリエステルを得た。この共重合ポリエステルを用いて実施例１と同様に特性の評価を行った。この結果を表１、２に示す。
【００４３】
【表１】

【００４４】
【表２】

【００４５】
【発明の効果】
本発明によれば、ポリエステルフィルムを製造する際、回転冷却ドラム上への密着性に優れ、静電ワイヤー汚れ、押出口金への昇華物付着を抑制し生産性に優れ、且つ衛生性に優れた共重合ポリエステルおよび該共重合ポリエステルからなる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 film using the copolymerized polyester and it more particularly, to an ethylene terephthalate as main repeating units, a copolyester melting point of from 205 to 253 ° C., difunctional carboxylic of the polyester A copolymerized polyester containing a sulfonic acid quaternary phosphonium salt having an ester-forming functional group of 0.1 to 45 mmol% based on the acid component as a copolymerization component, and having improved film-forming properties and excellent film productivity, and It relates to the film using.
[0002]
[Prior art]
Aromatic polyester films represented by polyethylene terephthalate film have excellent physical and chemical properties, and thus are used in a wide variety of applications such as magnetic tape, electrical insulation, capacitors, photography, and packaging.
[0003]
A polyester film is usually produced by rapidly cooling a film-like polyester melt melt-extruded from an extrusion die on the surface of a rotary cooling drum and then stretching it in the longitudinal and transverse directions. In this case, in order to eliminate the surface defects of the film and increase the uniformity of the thickness, a wire-shaped metal electrode (hereinafter referred to as an electrostatic wire) was provided in the vicinity of the surface of the extrusion die and the rotary cooling drum, and was melt extruded. A method of depositing an electrostatic charge on the surface (non-drum surface) of a film-like polyester film-like melt (hereinafter referred to as an electrostatic casting method) is known and widely used.
[0004]
Increasing productivity and reducing manufacturing costs in film formation is an important issue as well as improving film quality. To that end, it is necessary to increase the peripheral speed of the rotating cooling drum and improve the film formation speed. This is the most effective method. Therefore, when the peripheral speed of the rotating cooling drum is increased in the electrostatic casting method, the amount of electrostatic charge per unit area on the surface of the film-like object decreases, the adhesion to the rotating cooling drum decreases, and the film surface defect And problems such as non-uniform film thickness occur.
[0005]
In order to increase the adhesion, it is possible to increase the amount of electrostatic charge deposited on the molten polyester by increasing the voltage applied to the electrode, but if the applied voltage is increased too much, arc discharge will occur between the electrode and the rotating cooling drum. As a result, the film-like material on the surface of the cooling drum is destroyed, and the surface of the cooling drum may be damaged. Therefore, it is virtually impossible to increase the voltage applied to the electrodes to a certain extent.
[0006]
Various methods for reducing the specific resistance of molten polyester have been proposed as methods for overcoming the limitations of the electrostatic casting method and producing a polyester film with high efficiency by improving the film forming speed.
[0007]
For example, in Japanese Patent Publication No. 7-5765, a polymer chain contains a sulfonic acid quaternary phosphonium salt having an ester-forming functional group of 0.1 to 45 mmol% relative to a difunctional carboxylic acid component, and a molten film. It has been proposed to use an aromatic polyester having an AC volume resistivity value of 6.5 × 10 ⁸ Ωcm or less.
[0008]
However, when such a film forming method is carried out, sublimates that are thought to be generated from the film-like molten polyester extruded from the extrusion die adhere to the electrostatic wire as dirt, resulting in a current drop or discharge spark. As a result, the electrostatic wire needs to be replaced in a short time, and the sublimate adheres to the surface of the extrusion die to form streaky irregularities on the film surface. It has been found that there is a problem that productivity is extremely inferior, such as frequent cleaning. Moreover, when using the said polyester for films, such as a packaging use, from a sanitary viewpoint, it is necessary for the sulfonic acid quaternary phosphonium salt contained in polyester not to elute from a polyester film in large quantities. No mention is made of this.
[0009]
[Problems to be solved by the invention]
Therefore, when manufacturing the polyester film, the present inventors have excellent adhesion to the rotating cooling drum, suppress electrostatic wire dirt, sublimate adhesion to the extrusion die, and have excellent productivity and hygiene. As a result of intensive studies to obtain an excellent polyester, the present invention has been achieved.
[0010]
[Means for Solving the Problems]
That is, the present invention is a copolymer polyester having ethylene terephthalate as a main repeating unit and a melting point of 205 to 253 ° C., and 0.1 to 45 mmol% of ester formation with respect to the difunctional carboxylic acid component in the polyester. A copolymerized polyester comprising a sulfonic acid quaternary phosphonium salt having a functional functional group as a copolymerization component .
[0011]
In the present invention, the copolymer polyester needs to be occupied by 0.1 to 45 mmol% of the bifunctional carboxylic acid component constituting the polymer by the sulfonic acid quaternary phosphonium salt having an ester-forming functional group. If the amount of the sulfonic acid quaternary phosphonium salt is less than 0.1 mmol%, the film-forming speed cannot be improved. On the other hand, if it exceeds 45 mmol%, the surface defects of the film increase, which is not preferable.
[0012]
Preferred examples of the quaternary phosphonium salt having an ester-forming functional group include compounds represented by the following formulae.
[0013]
[Chemical 1]

[0014]
Here, A is a group containing an aromatic ring having 6 to 18 carbon atoms, Y ¹ and Y ² are the same or different and are a hydrogen atom or an ester-forming functional group (provided that Y ¹ and Y ² are simultaneously hydrogen And n is 1 or 2, and R ¹ , R ² , R ³ and R ⁴ are the same or different and are an alkyl group having 1 to 18 carbon atoms, a benzyl group or 6 to 12 carbon atoms. Of the aryl group.
[0015]
In the above formula, A is a group containing an aromatic ring having 6 to 18 carbon atoms. For example, a group containing a benzene skeleton, a naphthalene skeleton or a biphenyl skeleton can be mentioned as a preferred example. Such an aromatic ring may be substituted with, for example, an alkyl group having 1 to 12 carbon atoms in addition to Y ¹ , Y ² and a sulfonic acid quaternary phosphonium base.
[0016]
Y ¹ and Y ² are hydrogen atoms or ester-forming functional groups, and preferred examples include —COOH, —COOR ′, —OCOR ′, — (CH ₂ ) _n OH, — (OCH ₂ ) _n OH, and the like. be able to. In these groups, R ′ is a lower alkyl group having 1 to 4 carbon atoms or a phenyl group, and n is an integer of 1 to 10. Preferred examples of R ′ include methyl, ethyl, n-propyl, iso-propyl, n-butyl and the like. Further, the groups R ¹ , R ² , R ³ and R ⁴ constituting the sulfonic acid quaternary phosphonium base are the same or different from each other, and examples of the alkyl group having 1 to 18 carbon atoms include methyl, ethyl, propyl, butyl, Examples include dodecyl and stearyl. Examples of the aryl group having 6 to 12 carbon atoms include phenyl, naphthyl, biphenyl and the like.
[0017]
Preferred examples of the sulfonic acid quaternary phosphonium salt include tetrabutylphosphonium salt of 3,5-dicarboxybenzenesulfonic acid, ethyltributylphosphonium salt of 3,5-dicarboxybenzenesulfonic acid, and 3,5-dicarboxybenzenesulfone. Acid benzyltributylphosphonium salt, 3,5-dicarboxybenzenesulfonic acid phenyltributylphosphonium salt, 3,5-dicarboxybenzenesulfonic acid tetraphenylphosphonium salt, 3,5-dicarboxybenzenesulfonic acid butyltriphenylphosphonium salt, 3 , 5-Dicarbomethoxybenzenesulfonic acid tetrabutylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonic acid ethyltributylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonic acid benzyltributylphosphonium salt, 3,5-dicarbomethoxy Cybenzenesulfonic acid phenyltributylphosphonium salt, 3,5-di (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetrabutylphosphonium salt, 3,5-di (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetraphenylphosphonium salt, 3 , -Dicarboxybenzenesulfonic acid tetrabutylphosphonium salt, 3-dicarboxybenzenesulfonic acid tetraphenylphosphonium salt, 3-di (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetrabutylphosphonium salt, 3-di (β-hydroxyethoxy) Carbonyl) benzenesulfonic acid tetraphenylphosphonium salt, 4-di (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetrabutylphosphonium salt, bisphenol A-3,3 di (tetrabutylphosphonium sulfonic acid salt) , It can be exemplified 2,6-dicarboxylate naphthalene-4-sulfonic acid tetrabutylphosphonium salt. The said sulfonic acid quaternary phosphonium salt may be used individually by 1 type, or may use 2 or more types together.
[0018]
The copolymer polyester in the present invention contains ethylene terephthalate as a main repeating unit, and the copolymer component may be an acid component or an alcohol component. Examples of the copolymer acid component include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, Preferable examples include aromatic dicarboxylic acids such as 1,5-naphthalenedicarboxylic acid. On the other hand, preferred examples of the copolymer alcohol component include polyalkylene glycols such as propylene glycol, neopentyl glycol, butanediol, pentanediol, and hexanediol. These can be used alone or in combination of two or more.
[0019]
As a result, the copolymer component may have a polymer melting point in the range of 205 to 253 ° C. When the polymer melting point is lower than 205 ° C., the polymer crystallinity is lowered by copolymerization, and thus the polymer chips are fused in the drying process before film formation, and the productivity of the film is greatly reduced. On the other hand, when the polymer melting point exceeds 253 ° C., it is not possible to suppress contamination of the electrostatic wire and adhesion of sublimate to the extrusion die surface. Such a copolyester is a substantially linear polymer and has film-forming properties, particularly film-forming properties in the molten state.
[0020]
In addition, the amount of the copolyester is in a substantially linear range, and unless the effects of the present invention are impaired, for example, a polycarboxylic acid having 3 or more functional groups in an amount of 2 mol% or less with respect to the total acid component. Acids or polyhydroxy compounds such as trimellitic acid, pentaerythritol and the like can be copolymerized.
[0021]
Furthermore, the copolyester according to the present invention may contain additives such as pigments, dyes, antioxidants, light stabilizers, and light-shielding agents as necessary, as long as the surface flatness and dry heat deterioration are not impaired. It can be included.
[0022]
In the present invention, the sulfonic acid quaternary phosphonium salt occupies 0.1 to 45 mmol% of the total bifunctional carboxylic acid component, and the alternating volume resistivity when the copolymerized polyester is melted is 2.0 × 10 ⁸ Ωcm or less. It is possible to provide a sufficient amount of charge to adhere to a cooling drum that rotates relatively fast, and an improvement in the film forming speed, which is one of the objects of the present invention, can be achieved.
[0023]
The copolyester in the present invention can be produced by a known method. For example, for convenience, isophthalic acid copolymerized polyethylene terephthalate will be described as an example. Usually, terephthalic acid and isophthalic acid are directly esterified with ethylene glycol, or terephthalic acid such as dimethyl terephthalate and dimethyl isophthalate is used. First step of producing a terephthalic acid glycol ester and / or a low polymer thereof by transesterification of a lower alkyl ester of an acid with ethylene glycol or addition reaction of terephthalic acid and isophthalic acid with ethylene oxide And the second stage reaction in which the reaction product of the first stage is heated under reduced pressure and polycondensed to the desired degree of polymerization. At this time, an additive such as a catalyst can be arbitrarily used. In order to contain the sulfonic acid quaternary phosphonium salt in the copolymer polyester, it may be added to the reaction system at any stage until the synthesis of the copolymer polyester described above is completed, or the copolymer copolymer described above. The synthesis of the polyester is completed, and this and the sulfonic acid quaternary phosphonium salt may be fed, for example, into a vented twin-screw kneading extruder. In the latter case, the inventor's knowledge is preferable because the reaction of the sulfonic acid quaternary phosphonium salt can sufficiently proceed, and a simple and sufficient effect is exhibited.
[0024]
The copolymerized polyester of the present invention preferably contains 1 ppm or less of sulfonic acid quaternary phosphonium salt detected after immersion in a 50% ethanol solution at 250 ° F. for 2 hours. When the sulfonic acid quaternary phosphonium salt to be detected exceeds 1 ppm, it is not preferable when the film is used for food packaging. In order to reduce the detected amount of the sulfonic acid quaternary phosphonium salt to 1 ppm or less, the sulfonic acid quaternary phosphonium salt is added to the copolymerized polyester resin in the synthesis step of the copolymerized polyester resin or in the copolymer polyester production. What is necessary is just to add the sulfonic acid quaternary phosphonium salt by selecting an addition time such that the temperature in the system is 240 ° C. or higher for at least 3 minutes or longer.
[0025]
In the present invention, the copolymer polyester is molded into a film by, for example, extruding the copolymer polyester on a rotary cooling drum at a temperature of the melting point (Tm) to (Tm + 70) ° C. and rapidly cooling it, for example, 20 to 500 μm unstretched. Then, the unstretched film is uniaxially (longitudinal or transverse) and is 2.5 to 5.0 times at a temperature of (Tg-10) to (Tg + 70) ° C. (where Tg is the glass transition temperature of the polyester). A biaxially stretched film can be obtained by stretching at a magnification of 2.5 to 5.0 times at a temperature of (Tg) to (Tg + 70) ° C. in a direction perpendicular to the stretching direction. . The stretching method may be either sequential biaxial stretching or simultaneous biaxial stretching. Furthermore, the obtained film can be heat-set at a temperature of (Tg + 70) to (Tm) ° C. The heat setting time is, for example, 1 to 30 seconds.
[0026]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited by a following example, unless the summary is exceeded. In addition, the measurement of each characteristic value in an Example is based on the following method. Moreover, a part means a weight part.
[0027]
(1) AC container volume resistivity measurement of molten polymer A container in which a pair of electrodes is inserted into a polymer to be measured is immersed in a heating medium, and the polymer is heated and melted to a temperature of 285 ° C. and maintained at this temperature. A voltage of 100 V-50 Hz is applied from an AC power source connected to the electrode inserted into the polymer from the outside. The AC volume resistivity is obtained by calculation from the indicated values of the ammeter and voltmeter, the electrode area, and the distance between the electrodes.
[0028]
(2) When casting by applying a voltage of 6 kV between the cooling drum and an electrode placed near the die for melt-extruding the electrostatic cast polymer into a film and on the upper part of the extruded film The maximum cooling drum speed capable of stably forming a film without causing defects and without reducing the uniformity of thickness is obtained. The evaluation is performed by ranking as follows according to the maximum speed of the cooling drum.
Rank A: A film can be stably formed at a cooling drum speed of 70 m / min or more.
Rank B: The film can be stably formed at a cooling drum speed of 60 m / min or more and less than 70 m / min.
Rank C: A film can be stably formed at a cooling drum speed of 55 m / min or more and less than 60 m / min.
Rank D: The film can be stably formed only when the speed of the cooling drum is less than 55 m / min.
[0029]
(3) Dirty property of electrostatic wire In the electrostatic castability test of (2) above, the test time is extended and the rate of decrease in the current value of the electrostatic wire based on the stain on the electrostatic wire is examined. The current value at the start of the test and the current value at the end of the test are read, and the difference is divided by the test time to obtain the current decrease rate per unit time. It ranks and evaluates as follows according to the value.
Rank A: Current decrease rate 1% / less than hr Rank B: Current decrease rate 1% / hr or more and less than 5% / hr Rank C: Current decrease rate 5% / hr or more and less than 10% / hr Rank D: Current decrease rate 10 % / Hr or higher in rank A, there is no particular problem in practical use. In ranks B and C, the frequency of replacement of the electrostatic wire is increased, which is slightly disadvantageous in terms of production efficiency. Rank D cannot be put to practical use.
[0030]
(4) Sublimate adherence to the extrusion die When the sublimate adheres to the extrusion die, the molten polymer extruded from the die comes into contact with the deposit, and streaks are generated on the film surface. This is a method for determining the presence or absence of the streaks by visual observation, in which the molten polymer is extruded from an extrusion die, and after 8 hours, the film is brought into intimate contact with the rotating cooling drum and cooled to form a substantially amorphous film. The film is visually observed. If streaks are observed after 8 hours, the sublimate adhering to the extrusion die must be removed, resulting in poor productivity. The molten polymer temperature is set to a temperature that can be the lowest in the range that does not hinder the extrusion of the molten polymer in order to suppress adhesion of sublimate.
[0031]
(5) Film surface defect Evaluation of particulate foreign substances by-produced in the extrusion process from the polymerization of the copolymerized polyester, which is a film in a substantially amorphous state by extruding a molten polymer, closely contacting a rotating cooling drum and cooling. After that, the film is stretched 3.6 times in the longitudinal direction and 3.9 times in the transverse direction to produce a film having a thickness of 15 μm. This film is observed using a phase-contrast microscope, and the number of particles having a maximum length of 10 μm or more in the microscopic image is counted with an image analyzer Luzex 500 (manufactured by Nippon Regulator). Those having the number of particles of 10 / cm ² or less can be put to practical use. The molten polymer temperature is set to a temperature that can be the lowest in the range that does not hinder the extrusion of the molten polymer in order to suppress adhesion of sublimate.
[0032]
(6) Fusion between polymer chips in the drying process The maximum diameter of the fusion product between the polymer chips generated after drying for 4 hours at 160 ° C. is measured and ranked as follows.
Rank A: Maximum diameter of fusion material is less than 5 mm Rank B: Maximum diameter of fusion material is 5 mm or more and less than 10 mm Rank C: Maximum diameter of fusion material is 10 mm or more and less than 20 mm Rank D: Maximum diameter of fusion material is 20 mm or more If it is A or B, there is no problem in practical use. In rank C, when the chip is supplied to the extruder, the discharge is rarely changed, so that the productivity is slightly inferior. Rank D cannot be used practically.
[0033]
(7) Elution amount of sulfonic acid quaternary phosphonium salt by ethanol solution treatment Sample was taken so that the surface area of one side of the film was 25 inch ² and immersed in 50% ethanol solution, and 2 ° C. at 250 ° F. in an autoclave. Time-treated, the resulting extract is evaporated to dryness on a hot plate, methanol is added to the residue, and this is measured by high performance liquid chromatograph (Shimadzu LC-10AD). Quantify.
[0034]
[Example 1]
0.038 parts of manganese acetate tetrahydrate was added to a mixture of 88 parts of dimethyl terephthalate, 12 parts of dimethyl isophthalate and 70 parts of ethylene glycol, and the ester exchange reaction was carried out while gradually raising the temperature from 150 ° C to 240 ° C. It was. On the way, when the reaction temperature reached 170 ° C., 0.04 part of antimony trioxide was added, and further 0.2 part of spherical silica having an average particle size of 0.6 μm was added. A mixture of 0.034 parts of 5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt and 0.124 parts of ethylene glycol was added as a solution heated to 40 ° C. Subsequently, a transesterification reaction was carried out, and after completion of the transesterification reaction, trimethyl phosphate was heated in ethylene glycol at 135 ° C. for 5 hours under a pressure of 1.1 to 1.6 kg / cm 2 (trimethyl phosphate equivalent) 0.049 part) was added. Thereafter, the reaction product was transferred to a polymerization vessel, heated to 290 ° C., and subjected to a polycondensation reaction at a high vacuum of 0.2 mmHg or less to obtain a copolyester having an intrinsic viscosity of 0.60. The value of the AC volume resistivity at 285 ° C. of this copolymer polyester resin composition was 2.5 × 10 ⁷ Ω · cm.
[0035]
The copolymer polyester pellets were dried at 170 ° C. for 3 hours, then fed to an extruder hopper, melt extruded at 200 μm through a 1 mm slit die at a melting temperature of 280 ° C., and rotated at a surface temperature of 20 ° C. using a linear electrode. It was solidified on the cooling drum. At this time, the speed of the cooling drum was gradually increased, and the maximum casting speed at which a cooling film could be produced stably without causing surface defects due to poor adhesion was 100 m / min. Next, this unstretched film is preheated at 75 ° C., heated by a single IR heater with a surface temperature of 850 ° C. from above 15 mm between low-speed and high-speed rolls, and stretched 3.6 times in the longitudinal direction. This uniaxially stretched film was supplied to a stenter and stretched 3.9 times in the lateral direction at 105 ° C., and this was heat-set at 190 ° C. for 3 seconds to obtain a biaxially stretched film having a thickness of 14 μm. The properties of this film are shown in Tables 1 and 2.
[0036]
[Examples 2 and 3, Comparative Examples 1 and 2]
The same procedure as in Example 1 was carried out except that the amount of 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt was changed as shown in Table 1, or no 3,5 dicarboxybenzenesulfonic acid tetrabutylphosphonium salt was added. It was. The results are shown in Tables 1 and 2.
[0037]
[Example 4]
The same procedure as in Example 1 was performed except that tetraphenylphosphonium 3,5 dicarboxybenzenesulfonate was used instead of tetrabutylphosphonium 3,5 dicarboxybenzenesulfonate. The results are shown in Tables 1 and 2.
[0038]
[Examples 5 and 6 and Comparative Examples 3 and 4]
The same procedure as in Example 1 was performed except that the amount of isophthalic acid used as a copolymerization component was changed as shown in Table 1. However, the extrusion temperature of Comparative Example 3 was 285 ° C. The results are shown in Tables 1 and 2.
[0039]
[Example 7]
The same procedure as in Example 1 was performed except that 6 mol% of adipic acid was used as a copolymerization component. The results are shown in Tables 1 and 2.
[0040]
[Example 8]
In Example 1, the synthesis reaction of the copolymerized polyester resin was completed without adding 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt, and this was chipped. Next, this chip was supplied to a vented twin-screw kneading extruder at a rate of 20 kg / hr, and 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt was supplied to a rate of 12 mmol% with respect to this. . At this time, the same procedure as in Example 1 was performed except that the degree of vacuum of the vent hole was set to 1 mmHg, the temperature of the cylinder was 285 ° C., and melt-kneaded to obtain a copolyester. The results are shown in Tables 1 and 2.
[0041]
[Example 9]
100 parts of bis-β-hydroxyethyl ester of terephthalic acid / isophthalic acid = 88/12, 57 parts of terephthalic acid, 8 parts of isophthalic acid, 29 parts of ethylene glycol and tetrabutylphosphonium salt of 3,5-dicarboxybenzenesulfonic acid The esterification reaction was performed on 031 parts of the mixture at a temperature of 210 to 230 ° C. The reaction was terminated when the amount of distilled water generated by the reaction reached 13 parts, and a solution obtained by heat treating 0.027 parts of antimony trioxide and trimethyl phosphate per 100 parts of the reaction product at 135 ° C. for 5 hours. (0.002 parts in terms of trimethyl phosphate) was added. Thereafter, the reaction product was transferred to a polymerization vessel, heated to 290 ° C., and subjected to a polycondensation reaction in a high vacuum of 0.2 mmHg or less to obtain a copolyester. Properties were evaluated in the same manner as in Example 1 using this polyester. The results are shown in Tables 1 and 2.
[0042]
[Example 10]
Dimethyl terephthalate (DMT) 88 parts / hr, dimethyl isophthalate (DMI) 12 parts / hr and ethylene glycol 70 parts / hr, manganese acetate 0.05 mol% / (DMT + DMI), zinc acetate 0.01 mol% / (DMT + DMI) The catalyst was continuously fed to the continuous transesterification reaction tank together with the catalyst of the above, and the ester exchange reaction was carried out by heating to 150 to 250 ° C. while distilling methanol. Subsequently, the obtained transesterification reaction product was added with phosphorous acid 0.1 mol% / (DMT + DMI), 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt 0.01 mol% / (DMT + DMI), and three polymerization catalysts. After adding 0.03 mol% of antimony oxide / (DMT + DMI), it was continuously fed to the initial polymerization tank and reacted at 50 mmHg and 260 ° C. for 1 hour. Furthermore, this was reacted in an intermediate polymerization tank at 5 mmHg and 280 ° C. for 2 hours in the molten state, and then continuously fed to the final polymerization tank in a molten state and reacted at 1 mmHg and 290 ° C. for 10 minutes for copolymerization. Polyester was obtained. The characteristics were evaluated in the same manner as in Example 1 using this copolymerized polyester. The results are shown in Tables 1 and 2.
[0043]
[Table 1]

[0044]
[Table 2]

[0045]
【The invention's effect】
According to the present invention, when producing a polyester film, it is excellent in adhesion to a rotating cooling drum, is excellent in productivity by suppressing electrostatic wire dirt, sublimate adhesion to an extrusion die, and excellent in hygiene. Copolyester and a film comprising the copolyester can be provided.

Claims (4)

A copolymer polyester having ethylene terephthalate as a main repeating unit and a melting point of 205 to 253 ° C., and having 0.1 to 45 mmol% of ester-forming functional groups with respect to the difunctional carboxylic acid component in the polyester A copolymer polyester comprising an acid quaternary phosphonium salt as a copolymer component . The copolyester according to claim 1, wherein the sulfonic acid quaternary phosphonium salt detected after immersion in a 50% ethanol solution at 250 ° F for 2 hours is 1 ppm or less. A film produced from the copolyester according to claim 1 or 2. The film according to claim 3 formed by an electrostatic casting method.