JP3580633B2 - Heat-shrinkable polyester film, method for producing the same, and copolymerized polyester composition used therefor - Google Patents

Description

で表わされる単位と、１，４‐シクロヘキサンジメタノール単位、すなわち、式（ＩＩ）
【化２】

で表わされる単位及びエチレングリコール単位、すなわち、式（ＩＩＩ）
【化３】

で表わされる単位とから構成される共重合ポリエステルである。
【００１２】
この（Ａ）成分における式（ＩＩ）の単位と式（ＩＩＩ）の単位とは、好ましくはモル比で１０：９０ないし５０：５０、より好ましくは２０：８０ないし４０：６０の範囲内にある。式（ＩＩ）の単位がこれよりも少ないと、主収縮方向に対して直角の方向に熱膨張性を生じ、装着性が悪くなったり、十分な熱収縮性が得られなくなることがある。また、これよりも多くなると、主収縮方向に対して直角の方向に大きな熱伸縮性を生じ装着性が悪くなることがある。
【００１３】
本発明における（Ａ）成分は，前記した構造単位の他に、所望に応じ、ポリエステルの熱特性に影響を与えない量、通常５重量％以下の割合でアジピン酸、アゼライン酸などの脂肪族ジカルボン酸；ナフタレンジカルボン酸、ジフェニルジカルボン酸、ジフェニルスルホンジカルボン酸、ジフェニルエーテルジカルボン酸、ジフェニルケトンジカルボン酸、ナトリウムスルホイソフタル酸、ジブロモテレフタル酸などの芳香族ジカルボン酸；１，４‐シクロヘキサンジカルボン酸などの脂環式ジカルボン酸又はそれらのエステル形成性誘導体；１，３‐プロパンジオール、１，４‐ブタンジオール、１，５‐ペンタンジオール、１，６‐ヘキサンジオール、１，４‐ヘキサンジオール、１，７‐ヘプタンジオール、１，８‐オクタンジオール、１，９‐ノナンジオール、１，１０‐デカンジオール、ネオペンチルグリコール、２‐メチル‐１，８‐オクタンジオールなどの脂肪族ジオール；１，３‐シクロヘキサンジオール、１，４‐シクロヘキサンジオール、１，３‐シクロヘキサンジメタノール、ノルボルネンジメタノール、トリシクロデカンジメタノールなどの脂環式ジオール；２，２‐ビス（４‐ヒドロキシフェニル）プロパンのエチレンオキシド付加物、４，４’‐スルホニルビスフェノールのエチレンオキシド付加物、１，４‐ヒドロキシベンゼンのエチレンオキシド付加物などの芳香族ジオール；２‐ヒドロキシプロピオン酸、３‐ヒドロキシ酪酸、４‐ヒドロキシ吉草酸、５‐ヒドロキシカプロン酸、６‐エナント酸、７‐ヒドロキシカプリル酸、８‐ヒドロキシペラルゴン酸、９‐ヒドロキシカプリン酸などの脂肪族ヒドロキシカルボン酸；ヒドロキシ安息香酸、ヒドロキシトルイル酸、ヒドロキシナフトエ酸、３‐（ヒドロキシフェニル）プロピオン酸、ヒドロキシフェニル酢酸、３‐ヒドロキシ‐３‐フェニルプロピオン酸などの芳香族ヒドロキシカルボン酸；ヒドロキシメチルシクロヘキサンカルボン酸、ヒドロキシメチルノルボルネンカルボン酸、ヒドロキシメチルトリシクロデカンカルボン酸などの脂環式ヒドロキシカルボン酸又はそれらのエステル形成性誘導体などの二官能性化合物から誘導される構造単位を含むことができる。また、ポリエステルの物性をそこなわない程度の量、通常０．５重量％以下の割合であれば、トリメリット酸、トリメシン酸、ピロメリット酸、トリカルバリル酸などの三価以上の多価カルボン酸やトリメチロールプロパン、ペンタエリスルトールなどの三価以上の多価アルコールなどの多官能化合物から誘導される構造単位を含むこともできる。
【００１４】
この本発明の熱収縮性ポリエステルフィルムにおける（Ａ）成分は、ガラス転移温度が５０〜１００℃の範囲内であることが好ましい。このガラス転移温度がこれよりも低いと、熱収縮性フィルムとしたときに常温で自然収縮が生じてしまうので実用に適さない。このガラス転移温度がこれよりも高いと、熱収縮性フィルムとしたときの収縮開始温度が高く、被装着体への装着が困難となる。熱収縮性フィルムとしての使用において特に適する収縮開始温度を有するためには、ガラス転移温度は６０〜９０℃の範囲内であることがより好ましい。
【００１５】
また、この（Ａ）成分の極限粘度は、フェノールとテトラクロロエタンの等重量混合溶媒中、３０℃において０．４ｄｌ／ｇ以上であることが好ましい。この値よりも小さいと、熱収縮性フィルムとしたときの強度、耐衝撃性などの機械的性能が不十分となる。またこの値が大きすぎると、熱収縮性フィルムの製造における成形性の点が問題となる。したがって熱収縮性フィルムへの成形性、及びフィルムの機械的強度の点から、この極限粘度は０．５〜１．５ｄｌ／ｇの範囲内にあることがより好ましい。
【００１６】
本発明の熱収縮性ポリエステルフィルムにおける（Ａ）成分は、公知のポリエステルの製造方法、例えば米国特許第４，７８６，６９２号明細書記載の方法によりジカルボン酸とジオールを直接エステル化したのち、重縮合させる直接法、あるいはジカルボン酸低級アルキルエステル化合物とジオールをエステル交換したのち、重縮合させるエステル交換法を用いて製造することができる。通常、重合には、溶融重合法が用いられるが、高重合度のものが要求されるときには、溶融重合法と固相重合法との組み合せ、例えば溶融重合法で得られたポリエステルを減圧下又は不活性ガス気流下において、融点又は軟化点以下の温度で熱処理して固相重合させる方法が用いられる。
【００１７】
次に（Ａ）成分がテレフタル酸、１，４‐シクロヘキサンジメタノール及びエチレングリコールから誘導される構造単位を有する共重合ポリエステルの場合の製造方法について説明する。
すなわち、テレフタル酸に１，４‐シクロヘキサンジメタノール及びエチレングリコールから成るジオール混合物を、そのジオール混合物の合計量がテレフタル酸の量に対し、過剰量例えば１．１〜２．５倍モルとなるような割合で加え、常圧ないしは絶対圧３ｋｇ／ｃｍ^２以下の加圧下に、約２３０〜２８０℃の温度で生成する水を留出させながらエステル化反応を行い、次いで必要に応じて重縮合触媒、着色防止剤を添加したのち、５ｍｍＨｇ以下の圧力に減圧し、約２００〜２８０℃で、所望の極限粘度を有する共重合ポリエステルが得られるまで反応させる。この際に用いる重縮合触媒としては、例えば酸化アンチモンなどのアンチモン化合物、酸化ゲルマニウムなどのゲルマニウム化合物、テトラメトキシチタン、テトラエトキシチタン、テトラ‐ｎ‐プロポキシチタン、テトライソプロポキシチタン、テトラブトキシチタンなどのチタン化合物、ジ‐ｎ‐ブチルスズジラウレート、ジ‐ｎ‐ブチルスズオキシド、ジ‐ｎ‐ブチルスズジアセテートなどのスズ化合物等が挙げられ、これらの触媒の併用も可能である。この触媒は、生成する共重合ポリエステルに対して０．００２〜０．８重量％の範囲内となるような量で用いることが好ましい。また、前記着色防止剤としては、例えば亜リン酸、リン酸、トリメチルホスファイト、トリフェニルホスファイト、トリデシルホスファイト、トリメチルホスフェート、トリデシルホスフェート、トリフェニルホスフェート等のリン化合物を挙げることができ、生成する共重合ポリエステルに対し、０．００１〜０．５重量％の範囲内となるような量で用いる。
【００１８】
なお、テレフタル酸には通常イソフタル酸が不純物として含有されているが、この量が実質的に（Ａ）成分の物性をそこなわない限りそのまま使用しても差しつかえない。このようなテレフタル酸を用いると、（Ａ）成分の共重合ポリエステルＡ中にイソフタル酸から誘導される単位が混在することになる。
【００１９】
また、エステル交換反応による場合には、テレフタル酸アルキルエステルが用いられるが、このようなエステルの例としては、ジメチルテレフタレート、ジエチルテレフタレート、ジプロピルテレフタレートのような低級アルキルエステルを挙げることができる。
【００２０】
エステル交換反応法では、通常、エステル交換触媒の存在下に、ジオール混合物をテレフタル酸アルキルエステルに対して２．０〜４．０倍モルの割合で加え、常圧ないしは絶対圧３ｋｇ／ｃｍ^２以下の加圧下に、約１６０〜２５０℃で、生成するアルコールを留出させながらエステル交換反応を行った後に、上記した方法と同様に重縮合させるとよい。そして、エステル交換反応触媒としてはナトリウムメチラート、マグネシウムメチラートなどのアルカリ金属又はアルカリ土類金属のアルコラート；酢酸亜鉛、酢酸カドミウム、酢酸マンガン、酢酸コバルト、酢酸カルシウム、酢酸バリウムなどの金属の脂肪酸塩；ホウ酸亜鉛、ホウ酸カドミウム、ホウ酸マンガン、ホウ酸コバルト、ホウ酸カルシウム、ホウ酸バリウムなどの金属のホウ酸塩；炭酸亜鉛、炭酸カドミウム、炭酸マンガン、炭酸コバルト、炭酸カルシウム、炭酸バリウムなどの金属の炭酸塩；酸化マグネシウム、酸化鉛、酸化亜鉛、酸化錫、酸化ゲルマニウムなどの金属酸化物等を挙げることができる。
【００２１】
次に、本発明の（Ｂ）成分として用いられる共重合ポリエステルは、テレフタル酸単位、すなわち前記式（Ｉ）で表わされるジカルボン酸単位と、２‐メチル‐１，５‐ペンタンジオール単位又は３‐メチル‐１，５‐ペンタンジオール単位すなわち式（ＩＶ）
【化４】

（式中のＲ^１とＲ^２の中のいずれか一方はメチル基であり、他方は水素原子である）
で表わされるジオール単位及びエチレングリコール単位、すなわち式（ＩＩＩ）
【化５】

で表されるジオール単位とから構成される。
【００２２】
そして、この（Ｂ）成分の全構造単位中における式（ＩＶ）で表される２‐メチル‐１，５‐ペンタンジオール単位又は３‐メチル‐１，５‐ペンタンジオール単位と前記式（ＩＩＩ）で表わされるエチレングリコール単位とのモル比は、好ましくは５：９５ないし３５：６５であり、より好ましくは１０：９０ないし３０：７０の範囲内である。２‐メチル‐１，５‐ペンタンジオール単位又は３‐メチル‐１，５‐ペンタンジオール単位の含有割合がこれよりも少ないと熱収縮性フィルムとしたときの収縮率の限界値が低くなったり、あるいはガラス転移温度が高くなって、低温における収縮性に劣る。またこれよりも多いとガラス転移温度が低くなりすぎて、熱収縮性フィルムとしたときに室温付近で自然収縮を生じやすくなる。
【００２３】
本発明の熱収縮性ポリエステルフィルムの（Ｂ）成分は前記した構造単位に加え、必要に応じて炭素数３〜１８の脂肪族ジカルボン酸から誘導される構造単位を含有してもよい。共重合ポリエステルＢにおけるジカルボン酸単位中のテレフタル酸単位とこの脂肪族ジカルボン酸単位とのモル比は好ましくは９０：１０ないし９９．９：０．１、より好ましくは９５：５ないし９９．５：０．５の範囲内である。炭素数３〜１８の脂肪族ジカルボン酸単位を上記した割合で含有すると、熱収縮性フィルムとしたときにガラス転移温度が低くなり、また低温における収縮性も良好となる。さらに収縮速度も適度に低下し、びんなどの被装着体に加熱装着する際の収縮むら、しわ、波打ちなどが低減される。
【００２４】
この脂肪族ジカルボン酸単位の例としては、マロン酸、コハク酸、グルタル酸、アジピン酸、ピメリン酸、スベリン酸、アゼライン酸、セバシン酸、ウンデカンジカルボン酸、ドデカンジカルボン酸、ペンタデカンジカルボン酸、ヘキサデカンジカルボン酸、ヘプタデカンジカルボン酸、オクタデカンジカルボン酸などの脂肪族ジカルボン酸またはそれらのエステル形成性誘導体から誘導される構造単位を挙げることができる。このなかでも特に炭素数３〜１８の脂肪族ジカルボン酸単位がアジピン酸単位又はセバシン酸単位である場合は、容易に製造でき、熱収縮性フィルムとしたときに、びんなどの被装着体に加熱装着する際の収縮むら、しわ、波打ちなどがなく、極めて良好に被覆することが可能である。
【００２５】
本発明の熱収縮性ポリエステルフィルムにおける（Ｂ）成分のガラス転移温度は、４０〜８０℃の範囲内にあることが好ましい。ガラス転移温度が４０℃未満では、熱収縮性フィルムとしたときに常温付近で自然収縮が生じ、またガラス転移温度が８０℃を越えると、熱収縮性フィルムとしたとき収縮開始温度が高く、低温収縮性が低下する。熱収縮性フィルムとしての使用において特に適する収縮開始温度とするためには、ガラス転移温度は、特に５０〜７０℃、さらには５５〜７０℃の範囲内にあることが好ましい。
【００２６】
また、この（Ｂ）成分の極限粘度としては、フェノールとテトラクロロエタンの等重量混合溶媒中、３０℃において０．４ｄｌ／ｇ以上が好ましい。極限粘度が０．４ｄｌ／ｇより小さいと、熱収縮性フィルムとしたときの強度、耐衝撃性等の機械的性能が不十分となる。またこの値が大きすぎると、熱収縮性フィルムの製造における成形性の点が問題となる。したがって熱収縮性フィルムへの成形性、及びフィルムの機械的強度の点から、この極限粘度は０．５〜１．５ｄｌ／ｇの範囲内にあることがより好ましい。
【００２７】
この（Ｂ）成分は、公知の方法、例えば特開平７−１８８４００号公報に記載された方法、すなわちジカルボン酸とジオールを重縮合させる直接法、あるいはジカルボン酸低級アルキルエステル化合物とジオールをエステル交換反応によって重縮合反応させる方法により製造することができる。この重合は、溶融重合によることができるが、高重合度のものが要求されるときには、溶融重合と固相重合との組み合せ、例えば溶融重合で得られたポリエステルを減圧下又は不活性ガス気流下において融点又は軟化点以下の温度で熱処理して固相重合させることにより行うことができる。
【００２８】
次にテレフタル酸、セバシン酸、３‐メチル‐１，５‐ペンタンジオール及びエチレングリコールから誘導される構造単位を有する共重合ポリエステルの製造方法について説明する。
すなわち、テレフタル酸及びセバシン酸から成るジカルボン酸混合物と、３‐メチル‐１，５‐ペンタンジオール及びエチレングリコールから成るジオール混合物を、そのジオール混合物の合計量がテレフタル酸の量に対し、過剰量例えば１．１〜２．５倍モルとなるような割合で加え、常圧ないしは絶対圧３ｋｇ／ｃｍ^２以下の加圧下に、約２３０〜２８０℃の温度で、生成する水を留出させながらエステル化反応を行い、次いで必要に応じて重縮合触媒、着色防止剤を添加したのち、５ｍｍＨｇ以下の圧力に減圧し、約２００〜２８０℃で、所望の極限粘度を有する共重合ポリエステルが得られるまで反応させる。この際に用いる重縮合触媒としては、（Ａ）成分の製造において挙げた公知のものを用いることができる。ただし、ジオール混合物中の３‐メチル‐１，５‐ペンタンジオールの割合が高い場合には、重縮合性が著しく低下することがあるため、チタン化合物等の高活性の重合触媒を用いることが好ましい。この触媒は、生成する共重合ポリエステルに対して０．００２〜０．８重量％の範囲内となるような量で用いることが好ましい。また、前記着色防止剤としては、（Ａ）成分の製造例において挙げた公知のものを用いることができ、生成する共重合ポリエステルに対し、０．００１〜０．５重量％の範囲内となるような量で用いる。
【００２９】
また、エステル交換反応による場合には、（Ａ）成分の製造において挙げた公知のテレフタル酸の低級アルキルエステル及びエステル交換触媒を用いることができる。
【００３０】
本発明の製造方法においては、原料として、（Ａ）成分と、（Ｂ）成分とを、重量比４０：６０ないし９５：５、好ましくは５０：５０ないし８０：２０、より好ましくは６０：４０ないし７０：３０の割合で含む共重合ポリエステル組成物を用いる。（Ａ）成分と（Ｂ）成分の割合がこの範囲内であれば延伸処理した熱収縮性フィルムに加工して使用するに際し、びんなどに装着させるための加熱時に主収縮方向に対して直角の方向の伸縮を小さくすることができるが、４０：６０ないし９５：５の範囲外になると、延伸処理した熱収縮性フィルムに加工して使用するに際し、加熱時の伸縮を小さくすることができず、したがって被装着体に装着する際に生じる収縮むら、しわ、波打ちなどを抑制することができない。
【００３１】
この共重合ポリエステル組成物をフィルム状に加工するには、通常の熱可塑性ポリエステルフィルムの製造に慣用されている方法、すなわち製膜し、それと同時に又はその後で延伸し、さらに必要に応じて熱処理する。この製膜方法としては、特に制限はなく任意の方法を用いることができるが、キャスト法、インフレーション法などの押出成形法を用いるのが好ましい。また、このフィルムの延伸は、フィルム化と同時又はその後に（Ａ）成分と（Ｂ）成分とから成る共重合ポリエステル組成物のガラス転移温度より高い温度の範囲内において行われる。この際好ましい温度範囲はガラス転移温度ないしガラス転移温度より高い温度であり、好ましくはガラス転移温度より５ないし２０℃高い温度である。また延伸は少なくとも一軸方向に３〜７倍、より好ましくは３．５〜５．０倍延伸する。このようにして一軸方向に延伸することによりフィルムに一軸収縮性が付与される。例えば１００℃の熱水中に３０秒浸漬すると、主収縮方向に５０〜７０％、少なくとも４０％以上収縮し、その一方で主収縮方向に対して直角の方向には−５％ないし５％しか伸縮しない。したがって、フィルムを延伸することにより主収縮方向に対して直角方向には実質的に伸縮を示さない、良好な一軸収縮性のフィルムが得られ、これは被装着体への装着などに好適である。
【００３２】
上記のようにして延伸されたフィルムは、そのまま熱収縮性フィルムとして使用することが可能であるが、さらに熱処理してもよい。この熱処理は通常５０〜１５０℃の範囲内の温度で数秒間から数十秒間の範囲内の時間において、収縮性を喪失しないような条件下で行う。このような熱処理を行うことにより、熱収縮性フィルムの収縮率の調整、熱収縮性フィルム保存時の自然収縮の抑制、収縮後の収縮斑の減少など、寸法安定性を向上させることができる。
【００３３】
本発明の熱収縮性ポリエステルフィルムには、一般のポリエステル系熱収縮性フィルムの場合と同様、必要に応じ他の熱可塑性樹脂、紫外線安定剤、帯電防止剤、難燃剤、難燃補助剤、着色剤、潤滑剤、可塑剤、充填剤などを含有させることができる。また、この熱収縮性フィルムは、特定の性能を付与するために、通常行われている表面処理、例えば、紫外線、α線、β線、γ線、電子線などの照射、コロナ処理、プラズマ処理、火炎処理や、塩化ビニリデン、ポリアミド、ポリオレフィン、ポリビニルアルコールなどの樹脂被覆処理、金属蒸着等を施すことができる。
【００３４】
上記熱収縮性ポリエステルフィルムの厚さは、通常の熱収縮性フィルムの場合と同じく、用途に応じて適宜選択しうるが、通常１〜６００μｍの範囲内である。包装用途、特に、食品、飲料、医薬品等の包装用途においては、厚さが５〜３８０μｍの範囲のものが好適である。また、ポリエステルボトル、ガラス瓶等のボトルのラベルとして用いる場合には、厚さが２０〜７０μｍの範囲内のものが好適である。
【００３５】
【実施例】
次に本発明を実施例によってさらに詳細に説明する。
【００３６】
なお、実施例中の各物性は以下の方法で評価したものである。
（１）共重合ポリエステル中に導入された構造単位の含有割合
共重合ポリエステルを構成するテレフタル酸等の各モノマーから誘導されたそれぞれの構造単位について、共重合ポリエステル中の全構造単位に対する割合は、重水素化トリフルオロ酢酸を溶媒として、^１Ｈ−ＮＭＲ測定（日本電子株式会社製，ＪＮＭ−ＧＸ−２７０型）の結果から求めた。
【００３７】
（２）極限粘度
フェノールとテトラクロロエタンの等重量混合溶媒中、３０℃で、ウベローデ型粘度計（林製作所製「ＨＲＫ−３型」）を用いて測定した。
【００３８】
（３）ガラス転移温度（Ｔｇ）
ＪＩＳ Ｋ７１２１に準じて、示差熱分析法（ＤＳＣ）により、熱分析システム「メトラーＴＡ３０００」（メトラー社製）を用いて、昇温速度１０℃／分の条件で測定した。
【００３９】
（４）縦収縮性（主収縮方向に対して直角の方向の収縮率）
所定条件下で一軸延伸したフィルムを延伸方向に対して直角の方向（縦方向）に長さ１００ｍｍ、幅１０ｍｍの短ざく状に裁断して試験片とし、これを１００℃の熱水中に３０秒間浸漬し、０．５ｍｍ目盛のスケールで測定した数値から次式に従って、縦方向の熱収縮率（％）を求め、収縮分に＋、伸長分に−を付して示した。
【００４０】
【数１】

【００４１】
（５）横収縮性（主収縮方向の収縮率）
所定条件下で一軸延伸したフィルムを延伸方向（横方向）に長さ１００ｍｍ、幅１０ｍｍの短ざく状に裁断した試験片を用い、（４）と同様にして横方向の熱収縮率（％）を求めた。数値に付した＋と−の意味は（４）と同じである。
【００４２】
実施例１
テレフタル酸１００．００重量部、１，４‐シクロヘキサンジメタノール２８．９４重量部及びエチレングリコール４４．８３重量部からなるスラリーを調製し、これに０．０３５重量部の三酸化アンチモン及び０．０１０重量部の亜リン酸を加えたのち、加圧下（絶対圧２．５ｋｇ／ｃｍ^２）、２５０℃の温度でエステル化率が９５％になるまでエステル化を行い、低重合体を製造した。次いで、絶対圧１ｍｍＨｇの減圧下、２７０℃の温度でこの低重合体を重縮合し、極限粘度０．８０ｄｌ／ｇの共重合ポリエステルＡ^１を得た。
得られた共重合ポリエステルＡ^１における各構造単位の全構造単位に対する含有割合は、テレフタル酸単位５０モル％、１，４‐シクロヘキサンジメタノール１５モル％、エチレングリコール単位３４モル％、副生ジエチレングリコール単位１モル％であって、１，４‐シクロヘキサンジメタノール単位とエチレングリコール単位とのモル比は３０．６：６９．４であった。また、ガラス転移温度は８１℃であった。
【００４３】
テレフタル酸１００．００重量部、３‐メチル‐１，５‐ペンタンジオール１８．７２重量部及びエチレングリコール４４．８３重量部からなるスラリーを調製し、これに０．０３５重量部のテトライソプロポキシチタンを加えたのち、加圧下（絶対圧２．５ｋｇ／ｃｍ^２）、２５０℃の温度でエステル化率が９５％になるまでエステル化を行い、低重合体を製造した。次いで、この低重合体を絶対圧１ｍｍＨｇの減圧下、２７０℃の温度で重縮合し、極限粘度０．７３ｄｌ／ｇの共重合ポリエステルＢ^１を得た。
得られた共重合ポリエステルＢ^１における各構造単位の含有割合を、上記した方法で測定したところ、テレフタル酸単位５０モル％、３‐メチル‐１，５‐ペンタンジオール単位１２．５モル％、エチレングリコール単位３６モル％、副生ジエチレングリコール単位１．５モル％であって、３‐メチル‐１，５‐ペンタンジオール単位とエチレングリコール単位とのモル比は２５．８：７４．２であった。また、ガラス転移温度は５７℃であった。
【００４４】
上記で得られた共重合ポリエステルＡ^１及びＢ^１を用い、これらを表１に示す割合で混合し、２７０℃に加熱して溶融させ、Ｔ−ダイより３０℃の冷却ロール上に押し出し、厚さ０．２ｍｍ、幅６５０ｍｍの未延伸フィルムを得た。表１にそのガラス転移温度を示す。
【００４５】
次に、この未延伸フィルムを、表１に示す温度（ガラス転移温度より約１０℃高い温度）で３．８倍、４．０倍又は４．２倍に延伸し、厚さ約５０μｍの延伸フィルム（熱収縮性ポリエステルフィルム）を得た。このようにして得た各熱収縮性ポリエステルフィルムの縦及び横の収縮率を表１に示す。
【００４６】
【表１】

【００４７】
この表から明らかなように、共重合ポリエステルＡ^１単独で用いた場合（比較例）は、横方向（主収縮方向）への収縮率は良好であるが、縦方向（主収縮方向に対して直角の方向）への伸張率が高いため、加熱による装着処理の際に、しわや波打ちの原因となる。その一方、共重合ポリエステルＡ^１にＢ^１が４０：６０ないし９５：５の範囲内の割合で混合されると横方向（主収縮方向）への収縮率は良好に保ちつつ、縦方向（主収縮方向に対して直角の方向）への伸張率を抑えることがわかる。また、共重合ポリエステルＡ^１のＢ^１に対する割合がこれよりも小さくなると加熱時の縦方向への伸縮が大きくなっている。
【００４８】
実施例２
テレフタル酸９８．７０重量部、セバシン酸１．５９重量部、３‐メチル‐１，５‐ペンタンジオール１１．８５重量部及びエチレングリコール４４．８３重量部からなるスラリーを調整し、実施例１と同様にしてエステル化及び重縮合を行い、極限粘度０．７２ｄｌ／ｇの共重合ポリエステルＢ^２を得た。
得られた共重合ポリエステルＢ^２における各構造単位の含有割合は、テレフタル酸単位４９．３５モル％、セバシン酸単位０．６５モル％，３‐メチル‐１，５‐ペンタンジオール単位７．５０モル％、エチレングリコール単位４１．５０モル％、副生ジエチレングリコール単位１．００モル％であって、テレフタル酸単位とセバシン酸単位とのモル比は９８．７：１．３であり、３‐メチル‐１，５‐ペンタンジオール単位とエチレングリコール単位とのモル比は１５．３：８４．７であった。また、ガラス転移温度は６１℃であった。
【００４９】
実施例１で得られた共重合ポリエステルＡ^１及び上記のポリエステルＢ^２をそれぞれ用い、これらを表２に示す割合で混合し、実施例１と同様の方法で未延伸フィルム製造した。表２にそのガラス転移温度を示す。
【００５０】
次にこの未延伸フィルムを、表２に示す温度（ガラス転移温度より約１０℃高い温度）で３．８倍、４．０倍又は４．２倍に延伸し、厚さ約５０μｍの延伸フィルム（熱収縮性ポリエステルフィルム）を得た。このようにして得た各熱収縮性ポリエステルフィルムの縦及び横の収縮率を表２に示す。
【００５１】
【表２】

【００５２】
この表から明らかなように、共重合ポリエステルＡ^１単独で用いた場合（比較例）は、横方向（主収縮方向）への収縮率は良好であるが、縦方向（主収縮方向に対して直角の方向）への伸張率が高いため、加熱による装着処理の際に、しわや波打ちの原因となる。その一方、共重合ポリエステルＡ^１にＢ^２が４０：６０ないし９５：５の範囲内の割合で混合されると横方向（主収縮方向）への収縮率は良好に保ちつつ、縦方向（主収縮方向に対して直角の方向）への伸張率を抑えることがわかる。また、共重合ポリエステルＡ^１のＢ^２に対する割合がこれよりも小さくなると加熱時の縦方向への伸縮が大きくなっている。
【００５３】
実施例３
テレフタル酸９７．５０重量部、アジピン酸２．２０重量部、２‐メチル‐１，５‐ペンタンジオール１５．８１重量部及びエチレングリコール４４．８３重量部からなるスラリーを調製し、実施例１と同様にしてエステル化及び重縮合を行い、極限粘度０．７３ｄｌ／ｇの共重合ポリエステルＢ^３を得た。
【００５４】
得られた共重合ポリエステルＢ^３における各構造単位の含有割合は、テレフタル酸単位４８．７５モル％、アジピン酸単位１．２５モル％，２‐メチル‐１，５‐ペンタンジオール単位１０．００モル％、エチレングリコール単位３９．００モル％、副生ジエチレングリコール単位１．００モル％であって、テレフタル酸単位とアジピン酸単位とのモル比は９７．５：２．５であり、２‐メチル‐１，５‐ペンタンジオール単位とエチレングリコール単位とのモル比は２０．４：７９．６であった。また、ガラス転移温度は５６℃であった。
【００５５】
実施例１で得られた共重合ポリエステルＡ^１及び上記の共重合ポリエステルＢ^３をそれぞれ用い、これらを表３に示す割合で混合し、実施例１と同様な方法で未延伸フィルム製造した。そのガラス転移温度を表３に示す。
【００５６】
次に、この未延伸フィルムを、表３に示す温度（ガラス転移温度より約１０℃高い温度）で３．８倍、４．０倍又は４．２倍に延伸し、厚さ約５０μｍの延伸フィルム（熱収縮性ポリエステルフィルム）を得た。このようにして得た各熱収縮性ポリエステルフィルムの縦及び横の収縮率を表３に示す。
【００５７】
【表３】

【００５８】
この表から明らかなように、共重合ポリエステルＡ^１単独で用いた場合（比較例）は、横方向（主収縮方向）への収縮率は良好であるが、縦方向（主収縮方向に対して直角の方向）への伸張率が高いため、加熱による装着処理の際に、しわや波打ちの原因となる。その一方、共重合ポリエステルＡ^１へのＢ^３の混合割合を４０：６０ないし９５：５の範囲内に調整することにより方向（主収縮方向）への収縮率は良好に保ちつつ、縦方向（主収縮方向に対して直角の方向）への伸張率を抑えることがわかる。また、共重合ポリエステルＡ^１のＢ^３に対する割合がこれよりも小さくなると加熱時の縦方向への伸縮が大きくなっている。
【００５９】
比較例１
テレフタル酸１００重量部、エチレングリコール４４．８３重量部からなるスラリーを調製し、実施例１と同様にしてエステル化及び重縮合を行い、極限粘度０．７４ｄｌ／ｇのポリエチレンテレフタレート（ＰＥＴ）を得た。
【００６０】
得られたポリエチレンテレフタレートにおける各構造単位の含有割合は、テレフタル酸単位５０モル％、エチレングリコール単位４９モル％、副生ジエチレンングリコール単位１モル％であった。また、ガラス転移温度は８０℃であった。
【００６１】
実施例１で得られた共重合ポリエステルＡ^１及び上記のポリエチレンテレフタレートを用い、これらを表４に示す割合で混合し、実施例１と同様な方法で未延伸フィルム製造した。そのガラス転移温度を表４に示す。
【００６２】
次に、この未延伸フィルムを、表４に示す温度（ガラス転移温度より約１０℃高い温度）で３．８倍、４．０倍又は４．２倍に延伸し、厚さ約５０μｍの延伸フィルム（熱収縮性ポリエステルフィルム）を得た。このようにして得た各熱収縮性ポリエステルフィルムの縦及び横の収縮率を表４に示す。
【００６３】
【表４】

【００６４】
この表から明らかなように、Ｂ^１成分としてポリエチレンテレフタレートを用いた場合は、横方向（主収縮方向）への収縮率が小さいばかりでなく、縦方向（主収縮方向に対して直角方向）の伸張率を低く制御することができないため、加熱による装着過程においてしわや波打ちの原因となる。
【００６５】
参考例１
（Ａ）成分と（Ｂ）成分のそれぞれを表５〜８に示す重量比で混合し、表５〜８に示す延伸温度及び延伸倍率で延伸した熱収縮性ポリエステルフィルムについて装着性を調べた。すなわち、これらを用いて、円筒状の熱収縮性ポリエステルフィルム（折径１１３ｍｍ、高さ１１０ｍｍ）を形成させ、容量３３０ｍｌのガラスびん（最大径７０ｍｍ、最小径５０ｍｍ、高さ１９０ｍｍ）に嵌合し、長さ３ｍ、入口温度９０℃、出口温度９５℃の蒸気トンネル中を通過時間８秒で通過させることにより装着したものについて、目視により、しわ、収縮斑及び波打ちなどの収縮に起因する凹凸の有無を観察し、以下の基準により評価した。（試験は各試料について３回行った。）
◎…全く凹凸がない
○…１試料当り平均１個未満の凹凸あり
△…１試料当り平均１個以上２個未満の凹凸あり
×…１試料当り平均２個以上の凹凸あり
この結果を表５〜８に示す。
【００６６】
【表５】

【００６７】
【表６】

【００６８】
【表７】

【００６９】
【表８】

【００７０】
表５〜８から明らかなように、本発明の熱収縮性ポリエステルフィルムは、装着した後の外観は良好であり、一般のポリエステルフィルムに比べても優れている。特に共重合ポリエステルＡと共重合ポリエステルＢの重量比が７０：３０から６０：４０のときに良好であり、３．８倍に延伸したものが最も良好である。
【００７１】
参考例２
（Ａ）成分と（Ｂ）成分のそれぞれを表９に示す重量比で混合し、延伸倍率４．２倍、延伸温度８５℃の条件下で一軸延伸した熱収縮性ポリエステルフィルムについて、溶剤シール性を調べた。すなわちこのフィルムから２枚の試験片を裁断し、両者をテトラヒドロフランで接着し、２３℃で一昼夜放置したのち、両者の９０°剥離強度を経時的に測定し以下の基準で評価した。
○…力を加えてもフィルム同士が界面剥離しない
△…力を加えるとフィルム同士が界面剥離する
×…力を加えずにフィルム同士が界面剥離する
この結果を表９に示す。
【００７２】
【表９】

【００７３】
表９から明らかなように、本発明の熱収縮性ポリエステルフィルムは、優れた溶剤シール性を示し、びんなどの被装着体に装着する場合に適した形状に加工することができ、従来のポリエステルフィルムの溶剤シール性をはるかに改善するものであることがわかる。特にこの溶剤シール性は（Ａ）成分と（Ｂ）成分の重量比が８０：２０から６０：４０の値であるときに良好である。
【００７４】
【発明の効果】
本発明の熱収縮性ポリエステルフィルムは、主収縮方向において収縮率の限界値が大きく、低温収縮性に優れ、かつ収縮速度が緩和され、また主収縮方向に対して直角の方向に実質的な伸縮を示さないので、伸縮後のフィルムに、収縮斑、しわ、波打ち等のない良好な仕上りを与える。さらに溶剤シール性に優れるため、成形性もよい。したがって、被覆材、結束材、外装材、電気絶縁材など、殊に包装材、ラベル、キャップシールの材料として好適に用いることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a heat-shrinkable polyester film, more specifically, when heated, shows little expansion or contraction in a direction perpendicular to the main shrinkage direction, and does not cause wrinkles or uneven shrinkage when mounted on a bottle or the like. The present invention relates to a heat-shrinkable polyester film, a method for producing the same, and a copolymerized polyester composition used as a material for the film.
[0002]
[Prior art]
A heat-shrinkable film has a property of shrinking when heated by hot air, hot water, heat radiation, or the like, and is therefore used in a wide range of fields as a packaging material, a label, a cap seal, an electric insulating coating material, and the like.
[0003]
Polyvinyl chloride, polystyrene, polyolefin, copolyester, etc. are used as the material for this heat-shrinkable film. However, if the polyvinyl chloride film is incinerated after use, it emits toxic gas, causing environmental pollution. Therefore, its use tends to be gradually limited, polystyrene-based film has the disadvantage of spontaneous shrinkage during storage and shrinkage during use is insufficient, and polyolefin-based film has low low-temperature shrinkage Therefore, recently, a copolyester film has been attracting attention.
[0004]
By the way, the most widely used polyethylene terephthalate film among the copolyester films has excellent transparency, solvent resistance, weather resistance, high tensile strength, and no generation of toxic gas during incineration. It has the advantage that the limit value of shrinkage is lower than other films, the shrinkage start temperature is high, and when it exceeds the shrinkage start temperature, it reaches the limit value of shrinkage rate sharply and there is no room for control Has disadvantages. For this reason, when a heat-shrinkable film having a large shrinkage rate is heated in a shrink tunnel device, the shrinkage is completed instantaneously in the initial stage of the heat treatment, and the subsequent heating hardly shrinks, so that the film first enters the shrink tunnel device. A contraction difference occurs between the film part and the film part coming in later, and contraction unevenness, wrinkles, undulations and the like occur. In order to improve the drawbacks of such a heat-shrinkable polyester film, a structural unit derived from 1,4-cyclohexanedimethanol, neopentyl glycol or isophthalic acid is introduced into polyethylene terephthalate, and the amorphization and glass transition temperature are reduced. (JP-A-57-42726, JP-A-58-64958, JP-A-63-156833, JP-A-63-202429, and JP-B-63-7573). ), A copolymerized polyester in which a structural unit derived from isophthalic acid and 1,4-butanediol is introduced into polyethylene terephthalate (JP-A-63-114629), and a polyethylene terephthalate derived from 1,4-cyclohexanedimethanol. Polyesters and poly Mixture of Chi terephthalate (JP 61-64430 and JP Sho 62-95341) have been proposed.
[0005]
However, those containing structural units derived from 1,4-cyclohexane dimethanol, neopentyl glycol or isophthalic acid have been significantly improved in terms of increasing the limit of shrinkage, but have other shrinkage properties. Not always satisfactory. That is, the copolymerized polyester containing a structural unit derived from 1,4-cyclohexanedimethanol or neopentyl glycol has a high glass transition temperature or does not change when formed into a heat-shrinkable film. Because of the high shrinkage and the high shrinkage speed, it is not possible to completely prevent uneven spots, wrinkles, and undulations due to the difference in shrinkage. Polyester containing a structural unit derived from isophthalic acid has a slightly lower glass transition temperature than polyethylene terephthalate and a lower shrinkage start temperature, but has a lower shrinkage rate and a higher limit of shrinkage rate. There is not enough improvement in this respect. In addition, copolymerized polyesters containing structural units derived from isophthalic acid and 1,4-butanediol also have a lower glass transition temperature and a lower shrinkage start temperature than polyethylene terephthalate, but have a reduced shrinkage rate and shrinkage. The improvement in increasing the rate limit is insufficient. Thus, none of the above-mentioned copolymerized polyesters can completely overcome the above-mentioned disadvantages of polyethylene terephthalate.
[0006]
Also, a mixture of polyethylene terephthalate and a copolymerized polyester obtained by introducing a structural unit derived from 1,4-cyclohexanedimethanol into polyethylene terephthalate is one kind in terms of improving the limit value of the shrinkage rate or decreasing the shrinkage speed. Although it is improved over the material using the copolymerized polyester of the above, it is still insufficient in actual use. In addition, since the glass transition temperature is almost equal to that of polyethylene terephthalate, the shrinkage onset temperature is high, and when used as a heat-shrinkable film, wrinkles occur when a steam tunnel is used, which is a general method for mounting the film on an object. It is not possible to completely prevent the occurrence of spots, shrinkage, and waving. Further, in a sealing step using a solvent such as tetrahydrofuran for producing a cylindrical film or the like, there is also a disadvantage that the sealing property is reduced with time and sufficient strength cannot be obtained. As described above, no polyester film having satisfactory shrinkage characteristics under practical use conditions was obtained using any of the above-mentioned polyesters and mixtures thereof.
[0007]
On the other hand, in the case of a conventionally known copolymerized polyester, when a uniaxially stretched film is produced, it tends to expand in a direction perpendicular to the main shrinkage direction, and is formed into a cylindrical shape and fitted to a body such as a bottle. It is also known that, when mounted and heated, it temporarily expands during the shrinkage process, causing drawbacks such as wrinkles, shrinkage spots, and undulations.
[0008]
[Problems to be solved by the invention]
The present invention overcomes the drawbacks of the conventional heat-shrinkable polyester film, has a large limit value of shrinkage due to heat, has a low shrinkage initiation temperature, and has an appropriate shrinkage speed. Provides a heat-shrinkable polyester film that does not generate wrinkles, spots of shrinkage, waving, etc., hardly shows expansion in a direction perpendicular to the main shrinkage direction, and has excellent solvent sealing properties. It was done for the purpose of doing.
[0009]
[Means for Solving the Problems]
The present inventors have conducted various studies to improve the physical properties of the heat-shrinkable polyester film, and as a result, a copolymerized polyester obtained from terephthalic acid and 1,4-cyclohexanedimethanol and ethylene glycol, and terephthalic acid A novel copolymerized polyester composition is prepared by mixing a copolymerized polyester obtained from 2-methyl-1,5-pentanediol or 3-methyl-1,5-pentanediol and ethylene glycol, and then is produced. film did Thereafter, the obtained film is stretched 3 to 7 times in one direction, and when heated, almost no expansion is observed in the direction perpendicular to the stretching direction, that is, the direction perpendicular to the main shrinkage direction, The present inventors have found that a heat-shrinkable polyester film having a large limit value of the rate and having a low shrinkage onset temperature and a low shrinkage rate can be obtained, and the present invention has been accomplished based on this finding.
[0010]
That is, the present invention relates to (A) a terephthalic acid unit When 1,4-cyclohexanedimethanol unit and ethylene glycol unit When And (B) a terephthalic acid unit When 2-methyl-1,5-pentanediol unit or 3-methyl-1,5-pentanediol unit and ethylene glycol unit When A copolyester composition comprising a copolyester composed of: in a weight ratio of 40:60 to 95: 5, and When immersed in hot water of 100 ° C for 30 seconds An object of the present invention is to provide a heat-shrinkable polyester film having a shrinkage ratio of at least 40% in a main shrinkage direction and a shrinkage ratio in a direction perpendicular to the main shrinkage direction of -5% to 5%.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The heat-shrinkable polyester film of the present invention comprises a copolymerized polyester composition containing two types of copolymerized polyesters of component (A) and component (B). The copolymerized polyester used as the component (A) has a terephthalic acid unit, ie, a compound represented by the formula (I):
Embedded image

Unit represented by When , 1,4-cyclohexanedimethanol unit, that is, the formula (II)
Embedded image

And an ethylene glycol unit, that is, a unit represented by the formula (III)
Embedded image

Unit represented by When Is a copolymerized polyester composed of
[0012]
The unit of the formula (II) and the unit of the formula (III) in the component (A) are preferably in a molar ratio of 10:90 to 50:50, more preferably 20:80 to 40:60. . If the unit of the formula (II) is smaller than this, thermal expansion occurs in a direction perpendicular to the main shrinkage direction, which may result in poor mounting properties or insufficient heat shrinkage. On the other hand, if it is larger than this, large thermal expansion and contraction may occur in the direction perpendicular to the main shrinkage direction, and the mounting property may deteriorate.
[0013]
The component (A) in the present invention may contain, in addition to the above-mentioned structural units, an aliphatic dicarboxylic acid such as adipic acid or azelaic acid in an amount that does not affect the thermal properties of the polyester, if necessary, usually in an amount of 5% by weight or less. Acids; aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylketonedicarboxylic acid, sodium sulfoisophthalic acid and dibromoterephthalic acid; alicyclic rings such as 1,4-cyclohexanedicarboxylic acid Formula dicarboxylic acids or their ester-forming derivatives; 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-hexanediol, 1,7- Heptanediol, 1,8-octanediol Aliphatic diols such as 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, 2-methyl-1,8-octanediol; 1,3-cyclohexanediol, 1,4-cyclohexanediol, Alicyclic diols such as 3-cyclohexanedimethanol, norbornenedimethanol, and tricyclodecanedimethanol; ethylene oxide adducts of 2,2-bis (4-hydroxyphenyl) propane and ethylene oxide adducts of 4,4'-sulfonylbisphenol Aromatic diols such as ethylene oxide adducts of 1,4-hydroxybenzene and the like; 2-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxycaproic acid, 6-enanthic acid, 7-hydroxycaprylic acid , 8-Hydroxype Aliphatic hydroxycarboxylic acids such as lugonic acid and 9-hydroxycapric acid; hydroxybenzoic acid, hydroxytoluic acid, hydroxynaphthoic acid, 3- (hydroxyphenyl) propionic acid, hydroxyphenylacetic acid, 3-hydroxy-3-phenylpropionic acid Derived from bifunctional compounds such as aromatic hydroxycarboxylic acids such as alicyclic hydroxycarboxylic acids such as hydroxymethylcyclohexanecarboxylic acid, hydroxymethylnorbornenecarboxylic acid, and hydroxymethyltricyclodecanecarboxylic acid, and ester-forming derivatives thereof. May be included. In addition, if the amount does not impair the physical properties of the polyester, usually a proportion of 0.5% by weight or less, trivalent or higher polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid, and tricarballylic acid can be used. And a structural unit derived from a polyfunctional compound such as a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol.
[0014]
The component (A) in the heat-shrinkable polyester film of the present invention preferably has a glass transition temperature in the range of 50 to 100 ° C. If the glass transition temperature is lower than this, natural shrinkage occurs at room temperature when a heat-shrinkable film is formed, which is not suitable for practical use. If the glass transition temperature is higher than this, the shrinkage starting temperature of the heat-shrinkable film is high, and it is difficult to mount the film on the object. In order to have a particularly suitable shrinkage onset temperature for use as a heat shrinkable film, the glass transition temperature is more preferably in the range of 60 to 90 ° C.
[0015]
The intrinsic viscosity of the component (A) is preferably 0.4 dl / g or more at 30 ° C. in a mixed solvent of an equal weight of phenol and tetrachloroethane. If the value is smaller than this value, mechanical properties such as strength and impact resistance of the heat-shrinkable film become insufficient. On the other hand, if this value is too large, there is a problem of moldability in the production of a heat-shrinkable film. Therefore, from the viewpoint of moldability into a heat-shrinkable film and mechanical strength of the film, the intrinsic viscosity is more preferably in the range of 0.5 to 1.5 dl / g.
[0016]
The component (A) in the heat-shrinkable polyester film of the present invention is obtained by directly esterifying a dicarboxylic acid and a diol by a known polyester production method, for example, a method described in US Pat. No. 4,786,692, The compound can be produced by a direct method of condensing or a transesterification method of transesterifying a diol with a lower alkyl ester of a dicarboxylic acid and then performing polycondensation. Usually, a melt polymerization method is used for polymerization, but when a high degree of polymerization is required, a combination of the melt polymerization method and the solid phase polymerization method, for example, a polyester obtained by the melt polymerization method under reduced pressure or In an inert gas stream, a method of performing heat treatment at a temperature equal to or lower than the melting point or the softening point to perform solid phase polymerization is used.
[0017]
Next, a production method in which the component (A) is a copolyester having a structural unit derived from terephthalic acid, 1,4-cyclohexanedimethanol and ethylene glycol will be described.
That is, a diol mixture composed of 1,4-cyclohexanedimethanol and ethylene glycol is added to terephthalic acid so that the total amount of the diol mixture becomes an excess amount, for example, 1.1 to 2.5 times the amount of terephthalic acid. Normal pressure or absolute pressure 3kg / cm ² The esterification reaction is performed while distilling off water produced at a temperature of about 230 to 280 ° C. under the following pressure, and then, if necessary, a polycondensation catalyst and a coloring inhibitor are added, and then the pressure is reduced to 5 mmHg or less. The reaction is performed under reduced pressure at about 200 to 280 ° C. until a copolymerized polyester having a desired intrinsic viscosity is obtained. Examples of the polycondensation catalyst used at this time include, for example, antimony compounds such as antimony oxide, germanium compounds such as germanium oxide, tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium and the like. Examples include tin compounds such as titanium compounds, di-n-butyltin dilaurate, di-n-butyltin oxide, and di-n-butyltin diacetate. These catalysts can be used in combination. This catalyst is preferably used in such an amount as to be in the range of 0.002 to 0.8% by weight based on the produced copolyester. Examples of the coloring inhibitor include phosphorus compounds such as phosphorous acid, phosphoric acid, trimethyl phosphite, triphenyl phosphite, tridecyl phosphite, trimethyl phosphate, tridecyl phosphate, and triphenyl phosphate. It is used in such an amount as to be in the range of 0.001 to 0.5% by weight based on the produced copolymerized polyester.
[0018]
In addition, terephthalic acid usually contains isophthalic acid as an impurity, but this amount can be used as long as the physical properties of the component (A) are not substantially impaired. When such terephthalic acid is used, units derived from isophthalic acid are mixed in the copolyester A of the component (A).
[0019]
In the case of transesterification, terephthalic acid alkyl esters are used. Examples of such esters include lower alkyl esters such as dimethyl terephthalate, diethyl terephthalate and dipropyl terephthalate.
[0020]
In the transesterification reaction method, usually, a diol mixture is added at a ratio of 2.0 to 4.0 moles relative to the alkyl terephthalate in the presence of a transesterification catalyst, and the pressure is atmospheric pressure or absolute pressure of 3 kg / cm. ² The ester exchange reaction may be carried out under the following pressure at about 160 to 250 ° C. while distilling off the produced alcohol, and then the polycondensation may be carried out in the same manner as described above. Examples of the transesterification catalyst include alkali metal or alkaline earth metal alcoholates such as sodium methylate and magnesium methylate; fatty acid salts of metals such as zinc acetate, cadmium acetate, manganese acetate, cobalt acetate, calcium acetate, and barium acetate. A borate of a metal such as zinc borate, cadmium borate, manganese borate, cobalt borate, calcium borate, barium borate; zinc carbonate, cadmium carbonate, manganese carbonate, cobalt carbonate, calcium carbonate, barium carbonate, etc. And metal oxides such as magnesium oxide, lead oxide, zinc oxide, tin oxide, and germanium oxide.
[0021]
Next, the copolymerized polyester used as the component (B) of the present invention comprises a terephthalic acid unit, that is, a dicarboxylic acid unit represented by the above formula (I) and a 2-methyl-1,5-pentanediol unit or 3-methylphthalene unit. Methyl-1,5-pentanediol unit, ie, formula (IV)
Embedded image

(R in the formula ¹ And R ² Is a methyl group and the other is a hydrogen atom)
A diol unit and an ethylene glycol unit represented by the following formula (III):
Embedded image

And a diol unit represented by
[0022]
Then, 2-methyl-1,5-pentanediol unit or 3-methyl-1,5-pentanediol unit represented by the formula (IV) in all structural units of the component (B) and the above-mentioned formula (III) The molar ratio to the ethylene glycol unit represented by the formula is preferably from 5:95 to 35:65, more preferably from 10:90 to 30:70. If the content ratio of 2-methyl-1,5-pentanediol unit or 3-methyl-1,5-pentanediol unit is smaller than this, the limit value of the shrinkage ratio when the heat-shrinkable film is reduced or Alternatively, the glass transition temperature increases, and the shrinkage at low temperatures is inferior. On the other hand, if it is more than this, the glass transition temperature becomes too low, and when a heat-shrinkable film is formed, natural shrinkage tends to occur near room temperature.
[0023]
The component (B) of the heat-shrinkable polyester film of the present invention may contain a structural unit derived from an aliphatic dicarboxylic acid having 3 to 18 carbon atoms, if necessary, in addition to the structural units described above. The molar ratio of the terephthalic acid unit to the aliphatic dicarboxylic acid unit in the dicarboxylic acid unit in the copolymerized polyester B is preferably 90:10 to 99.9 : 0.1, more preferably in the range of 95: 5 to 99.5: 0.5. When the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms is contained in the above-described ratio, the glass transition temperature of the heat-shrinkable film becomes low, and the shrinkability at low temperature becomes good. Further, the shrinkage speed is appropriately reduced, and uneven shrinkage, wrinkles, waving, and the like at the time of heating and mounting on a body such as a bottle are reduced.
[0024]
Examples of the aliphatic dicarboxylic acid unit include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, pentadecanedicarboxylic acid, and hexadecanedicarboxylic acid And a structural unit derived from an aliphatic dicarboxylic acid such as heptadecanedicarboxylic acid and octadecanedicarboxylic acid, or an ester-forming derivative thereof. Among them, particularly when the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms is an adipic acid unit or a sebacic acid unit, it can be easily produced, and when a heat-shrinkable film is formed, heat is applied to an object such as a bottle. There is no uneven shrinkage, wrinkles, or undulations at the time of mounting, and it is possible to coat very well.
[0025]
The glass transition temperature of the component (B) in the heat-shrinkable polyester film of the present invention is preferably in the range of 40 to 80 ° C. If the glass transition temperature is less than 40 ° C., spontaneous shrinkage occurs at around room temperature when the heat shrinkable film is formed, and if the glass transition temperature exceeds 80 ° C., the shrinkage start temperature is high when the heat shrinkable film is formed, Shrinkage decreases. The glass transition temperature is preferably in the range of 50 to 70 ° C., more preferably 55 to 70 ° C., in order to obtain a shrink start temperature particularly suitable for use as a heat shrinkable film.
[0026]
The intrinsic viscosity of the component (B) is preferably 0.4 dl / g or more at 30 ° C. in a mixed solvent of phenol and tetrachloroethane in the same weight. When the intrinsic viscosity is less than 0.4 dl / g, mechanical properties such as strength and impact resistance of the heat-shrinkable film become insufficient. On the other hand, if this value is too large, there is a problem of moldability in the production of a heat-shrinkable film. Therefore, from the viewpoint of moldability into a heat-shrinkable film and mechanical strength of the film, the intrinsic viscosity is more preferably in the range of 0.5 to 1.5 dl / g.
[0027]
The component (B) can be obtained by a known method, for example, a method described in JP-A-7-188400, that is, a direct method of polycondensing a dicarboxylic acid and a diol, or a transesterification reaction between a lower alkyl ester compound of a dicarboxylic acid and a diol. To produce a polycondensation reaction. This polymerization can be carried out by melt polymerization, but when a high degree of polymerization is required, a combination of melt polymerization and solid phase polymerization, for example, a polyester obtained by melt polymerization is subjected to reduced pressure or an inert gas stream. , And heat-treated at a temperature equal to or lower than the melting point or the softening point to carry out solid-phase polymerization.
[0028]
Next, a method for producing a copolymerized polyester having a structural unit derived from terephthalic acid, sebacic acid, 3-methyl-1,5-pentanediol and ethylene glycol will be described.
That is, a dicarboxylic acid mixture consisting of terephthalic acid and sebacic acid and a diol mixture consisting of 3-methyl-1,5-pentanediol and ethylene glycol, the total amount of the diol mixture being an excess amount relative to the amount of terephthalic acid, At normal pressure or absolute pressure of 3 kg / cm ² The esterification reaction is carried out under the following pressure at a temperature of about 230 to 280 ° C. while distilling off the generated water, and then, if necessary, a polycondensation catalyst and a coloring inhibitor are added. The reaction is carried out at about 200 to 280 ° C. until a copolymerized polyester having a desired intrinsic viscosity is obtained. As the polycondensation catalyst used at this time, the known catalysts mentioned in the production of the component (A) can be used. However, when the proportion of 3-methyl-1,5-pentanediol in the diol mixture is high, the polycondensation property may be significantly reduced. Therefore, it is preferable to use a highly active polymerization catalyst such as a titanium compound. . This catalyst is preferably used in such an amount as to be in the range of 0.002 to 0.8% by weight based on the produced copolyester. In addition, as the coloring inhibitor, the known ones mentioned in the production examples of the component (A) can be used, and it is in the range of 0.001 to 0.5% by weight based on the produced copolymerized polyester. Use in such amounts.
[0029]
In the case of transesterification, known lower alkyl esters of terephthalic acid and transesterification catalysts mentioned in the production of component (A) can be used.
[0030]
In the production method of the present invention, the components (A) and (B) are used as raw materials in a weight ratio of 40:60 to 95: 5, preferably 50:50 to 80:20, more preferably 60:40. To a copolyester composition containing a ratio of 70:30 to 70:30. When the ratio of the component (A) and the component (B) is within this range, when processed into a stretch-treated heat-shrinkable film and used, it is perpendicular to the main shrinkage direction during heating for mounting on a bottle or the like. The expansion and contraction in the direction can be reduced. However, when the expansion and contraction is out of the range of 40:60 to 95: 5, the expansion and contraction during heating cannot be reduced when processed into a stretched heat-shrinkable film for use. Therefore, uneven shrinkage, wrinkles, undulations, and the like that occur when the device is mounted on the body cannot be suppressed.
[0031]
In order to process the copolymerized polyester composition into a film, a method commonly used for the production of a normal thermoplastic polyester film, that is, a film is formed, and at the same time or thereafter stretched, and further heat-treated as necessary . The film forming method is not particularly limited, and any method can be used. However, it is preferable to use an extrusion method such as a casting method or an inflation method. The stretching of the film is performed at the same time or after the film formation in a temperature range higher than the glass transition temperature of the copolymerized polyester composition comprising the components (A) and (B). The preferred temperature range is the glass transition temperature or a temperature higher than the glass transition temperature, preferably a temperature 5 to 20 ° C. higher than the glass transition temperature. The stretching is performed at least 3 to 7 times, more preferably 3.5 to 5.0 times in the uniaxial direction. By stretching in the uniaxial direction in this way, uniaxial shrinkage is imparted to the film. For example, at 100 ° C hot water 30 in Second When immersed, it shrinks by 50-70% in the main shrink direction, at least 40% or more, while it expands and contracts only -5% to 5% in the direction perpendicular to the main shrink direction. Therefore, by stretching the film, a film having good uniaxial shrinkage that does not substantially expand and contract in a direction perpendicular to the main shrinkage direction is obtained, which is suitable for mounting on a body to be mounted. .
[0032]
The film stretched as described above can be used as it is as a heat-shrinkable film, but may be further heat-treated. This heat treatment is usually performed at a temperature in the range of 50 to 150 ° C. for a time in the range of several seconds to several tens of seconds under conditions that do not cause loss of shrinkage. By performing such heat treatment, dimensional stability such as adjustment of the shrinkage of the heat-shrinkable film, suppression of natural shrinkage during storage of the heat-shrinkable film, and reduction of shrinkage spots after shrinkage can be improved.
[0033]
In the heat-shrinkable polyester film of the present invention, as in the case of a general polyester-based heat-shrinkable film, other thermoplastic resins, ultraviolet stabilizers, antistatic agents, flame retardants, flame retardant auxiliary agents, coloring if necessary. Agents, lubricants, plasticizers, fillers and the like. In addition, the heat-shrinkable film is subjected to a surface treatment that is usually performed to impart specific performance, for example, irradiation with ultraviolet rays, α-rays, β-rays, γ-rays, electron beams, corona treatment, and plasma treatment. , Flame treatment, resin coating treatment of vinylidene chloride, polyamide, polyolefin, polyvinyl alcohol, etc., metal vapor deposition, and the like.
[0034]
The thickness of the heat-shrinkable polyester film can be appropriately selected according to the application as in the case of the normal heat-shrinkable film, but is usually in the range of 1 to 600 μm. In packaging applications, particularly packaging applications for foods, beverages, pharmaceuticals, etc., those having a thickness in the range of 5 to 380 μm are suitable. When used as a label for bottles such as polyester bottles and glass bottles, those having a thickness in the range of 20 to 70 μm are suitable.
[0035]
【Example】
Next, the present invention will be described in more detail by way of examples.
[0036]
In addition, each physical property in an Example is evaluated by the following methods.
(1) Content of structural units introduced into copolymerized polyester
For each structural unit derived from each monomer such as terephthalic acid constituting the copolymerized polyester, the ratio to the total structural units in the copolymerized polyester is determined by using deuterated trifluoroacetic acid as a solvent. ¹ It was determined from the result of H-NMR measurement (JNM-GX-270, manufactured by JEOL Ltd.).
[0037]
(2) Intrinsic viscosity
In an equal weight mixed solvent of phenol and tetrachloroethane at 30 ° C, Uberode It was measured using a mold viscometer (“HRK-3 model” manufactured by Hayashi Seisakusho).
[0038]
(3) Glass transition temperature (Tg)
In accordance with JIS K7121, a thermal analysis system “Metra ー The measurement was performed using a “TA3000” (manufactured by Mettler) at a heating rate of 10 ° C./min.
[0039]
(4) longitudinal shrinkage (shrinkage in the direction perpendicular to the main shrinkage direction)
A film uniaxially stretched under predetermined conditions is cut into a strip having a length of 100 mm and a width of 10 mm in a direction perpendicular to the stretching direction (longitudinal direction) to obtain a test piece. hot water The film was immersed in the sample for 30 seconds, and the heat shrinkage (%) in the longitudinal direction was obtained from the numerical value measured on a 0.5 mm scale according to the following equation.
[0040]
(Equation 1)

[0041]
(5) Lateral shrinkage (shrinkage ratio in main shrinkage direction)
Using a test piece obtained by cutting a uniaxially stretched film in the stretching direction (transverse direction) into a short shape having a length of 100 mm and a width of 10 mm under predetermined conditions, the heat shrinkage in the transverse direction (%) in the same manner as (4) I asked. The meanings of + and-attached to the numerical values are the same as in (4).
[0042]
Example 1
A slurry comprising 100.00 parts by weight of terephthalic acid, 28.94 parts by weight of 1,4-cyclohexanedimethanol and 44.83 parts by weight of ethylene glycol was prepared, and 0.035 parts by weight of antimony trioxide and 0.010 parts by weight were prepared. After adding phosphorous acid by weight, pressurization (absolute pressure 2.5 kg / cm ² ), Esterification was carried out at a temperature of 250 ° C. until the esterification ratio reached 95% to produce a low polymer. Then, the low polymer was subjected to polycondensation under a reduced pressure of 1 mmHg at a temperature of 270 ° C. to obtain a copolymer A having an intrinsic viscosity of 0.80 dl / g. ¹ Got.
Copolyester A obtained ¹ Is 50 mol% of terephthalic acid units, 15 mol% of 1,4-cyclohexanedimethanol, 34 mol% of ethylene glycol units, and 1 mol% of by-product diethylene glycol units. The molar ratio of 1,4-cyclohexanedimethanol units to ethylene glycol units was 30.6: 69.4. The glass transition temperature was 81 ° C.
[0043]
A slurry composed of 100.00 parts by weight of terephthalic acid, 18.72 parts by weight of 3-methyl-1,5-pentanediol and 44.83 parts by weight of ethylene glycol was prepared, and 0.035 part by weight of tetraisopropoxy titanium was added thereto. And then pressurized (absolute pressure 2.5 kg / cm ² ), Esterification was carried out at a temperature of 250 ° C. until the esterification ratio reached 95% to produce a low polymer. Next, this low polymer is polycondensed at a temperature of 270 ° C. under a reduced pressure of 1 mmHg to obtain a copolymer B having an intrinsic viscosity of 0.73 dl / g. ¹ Got.
Copolyester B obtained ¹ The content ratio of each structural unit in the above was measured by the above-mentioned method. As a result, 50 mol% of terephthalic acid unit, 12.5 mol% of 3-methyl-1,5-pentanediol unit, 36 mol% of ethylene glycol unit, and by-product It was 1.5 mol% of diethylene glycol units, and the molar ratio of 3-methyl-1,5-pentanediol units to ethylene glycol units was 25.8: 74.2. The glass transition temperature was 57 ° C.
[0044]
Copolyester A obtained above ¹ And B ¹ These were mixed at the ratios shown in Table 1, heated to 270 ° C. and melted, and extruded from a T-die onto a 30 ° C. cooling roll to obtain an unstretched film having a thickness of 0.2 mm and a width of 650 mm. Was. Table 1 shows the glass transition temperature.
[0045]
Next, the unstretched film is stretched 3.8 times, 4.0 times or 4.2 times at the temperature shown in Table 1 (temperature higher than the glass transition temperature by about 10 ° C.), and stretched to a thickness of about 50 μm. A film (heat-shrinkable polyester film) was obtained. Table 1 shows the longitudinal and lateral shrinkage ratios of the thus obtained heat-shrinkable polyester films.
[0046]
[Table 1]

[0047]
As is clear from this table, the copolymerized polyester A ¹ When used alone (comparative example), the shrinkage rate in the horizontal direction (main shrinkage direction) is good, but the elongation rate in the vertical direction (direction perpendicular to the main shrinkage direction) is high. Causes wrinkles and undulations during the mounting process. On the other hand, copolymerized polyester A ¹ To B ¹ Is mixed at a ratio in the range of 40:60 to 95: 5, while the shrinkage in the horizontal direction (main shrinkage direction) is kept good, while the shrinkage in the vertical direction (direction perpendicular to the main shrinkage direction) is maintained. It can be seen that the elongation rate is suppressed. In addition, copolymerized polyester A ¹ Of B ¹ If the ratio to is smaller than this, the expansion and contraction in the vertical direction during heating increases.
[0048]
Example 2
A slurry comprising 98.70 parts by weight of terephthalic acid, 1.59 parts by weight of sebacic acid, 11.85 parts by weight of 3-methyl-1,5-pentanediol and 44.83 parts by weight of ethylene glycol was prepared. Esterification and polycondensation are performed in the same manner to obtain a copolyester B having an intrinsic viscosity of 0.72 dl / g. ² Got.
Copolyester B obtained ² Are 49.35 mol% of terephthalic acid units, 0.65 mol% of sebacic acid units, 7.50 mol% of 3-methyl-1,5-pentanediol units, and 41.50 of ethylene glycol units. Mol%, 1.00 mol% of by-produced diethylene glycol units, the molar ratio of terephthalic acid units to sebacic acid units is 98.7: 1.3, and 3-methyl-1,5-pentanediol units The molar ratio to the ethylene glycol units was 15.3: 84.7. The glass transition temperature was 61 ° C.
[0049]
Copolyester A obtained in Example 1 ¹ And the above polyester B ² Were mixed at the ratios shown in Table 2, and an unstretched film was produced in the same manner as in Example 1. Table 2 shows the glass transition temperature.
[0050]
Next, this unstretched film is stretched 3.8 times, 4.0 times or 4.2 times at the temperature shown in Table 2 (temperature higher than the glass transition temperature by about 10 ° C.), and the stretched film having a thickness of about 50 μm is obtained. (Heat-shrinkable polyester film) was obtained. Table 2 shows the longitudinal and lateral shrinkage ratios of the heat-shrinkable polyester films thus obtained.
[0051]
[Table 2]

[0052]
As is clear from this table, the copolymerized polyester A ¹ When used alone (comparative example), the shrinkage rate in the horizontal direction (main shrinkage direction) is good, but the elongation rate in the vertical direction (direction perpendicular to the main shrinkage direction) is high. Causes wrinkles and undulations during the mounting process. On the other hand, copolymerized polyester A ¹ To B ² Is mixed at a ratio in the range of 40:60 to 95: 5, while the shrinkage in the horizontal direction (main shrinkage direction) is kept good, while the shrinkage in the vertical direction (direction perpendicular to the main shrinkage direction) is maintained. It can be seen that the elongation rate is suppressed. In addition, copolymerized polyester A ¹ Of B ² If the ratio to is smaller than this, the expansion and contraction in the vertical direction during heating increases.
[0053]
Example 3
A slurry comprising 97.50 parts by weight of terephthalic acid, 2.20 parts by weight of adipic acid, 15.81 parts by weight of 2-methyl-1,5-pentanediol and 44.83 parts by weight of ethylene glycol was prepared. Esterification and polycondensation are performed in the same manner to obtain a copolyester B having an intrinsic viscosity of 0.73 dl / g. ³ Got.
[0054]
Copolyester B obtained ³ Are 48.75 mol% of terephthalic acid units, 1.25 mol% of adipic acid units, 10.00 mol% of 2-methyl-1,5-pentanediol units, and 39.00 ethylene glycol units. Mole%, 1.00 mole% of by-product diethylene glycol units, the molar ratio of terephthalic acid units to adipic acid units is 97.5: 2.5, and 2-methyl-1,5-pentanediol units The molar ratio to the ethylene glycol units was 20.4: 79.6. The glass transition temperature was 56 ° C.
[0055]
Copolyester A obtained in Example 1 ¹ And the above-mentioned copolymerized polyester B ³ Were mixed at the ratios shown in Table 3, and an unstretched film was produced in the same manner as in Example 1. Table 3 shows the glass transition temperature.
[0056]
Next, the unstretched film is stretched 3.8 times, 4.0 times or 4.2 times at the temperature shown in Table 3 (temperature higher than the glass transition temperature by about 10 ° C.), and stretched to a thickness of about 50 μm. A film (heat-shrinkable polyester film) was obtained. Table 3 shows the longitudinal and lateral shrinkage ratios of the heat-shrinkable polyester films thus obtained.
[0057]
[Table 3]

[0058]
As is clear from this table, the copolymerized polyester A ¹ When used alone (comparative example), the shrinkage rate in the horizontal direction (main shrinkage direction) is good, but the elongation rate in the vertical direction (direction perpendicular to the main shrinkage direction) is high. Causes wrinkles and undulations during the mounting process. On the other hand, copolymerized polyester A ¹ B to ³ By adjusting the mixing ratio in the range of 40:60 to 95: 5, the shrinkage ratio in the direction (main shrinking direction) is kept good while the longitudinal direction (direction perpendicular to the main shrinking direction) is maintained. It can be seen that the elongation rate is suppressed. In addition, copolymerized polyester A ¹ Of B ³ If the ratio to is smaller than this, the expansion and contraction in the vertical direction during heating increases.
[0059]
Comparative Example 1
A slurry comprising 100 parts by weight of terephthalic acid and 44.83 parts by weight of ethylene glycol was prepared and subjected to esterification and polycondensation in the same manner as in Example 1 to obtain polyethylene terephthalate (PET) having an intrinsic viscosity of 0.74 dl / g. Was.
[0060]
The content ratio of each structural unit in the obtained polyethylene terephthalate was 50 mol% of terephthalic acid units, 49 mol% of ethylene glycol units, and 1 mol% of by-product diethylene glycol units. The glass transition temperature was 80 ° C.
[0061]
Copolyester A obtained in Example 1 ¹ Using the above polyethylene terephthalate and mixing them in the proportions shown in Table 4, an unstretched film was produced in the same manner as in Example 1. Table 4 shows the glass transition temperature.
[0062]
Next, the unstretched film is stretched 3.8 times, 4.0 times or 4.2 times at the temperature shown in Table 4 (temperature higher than the glass transition temperature by about 10 ° C.), and stretched to a thickness of about 50 μm. A film (heat-shrinkable polyester film) was obtained. Table 4 shows the longitudinal and lateral shrinkage ratios of the heat-shrinkable polyester films thus obtained.
[0063]
[Table 4]

[0064]
As is clear from this table, B ¹ When polyethylene terephthalate is used as a component, not only is the contraction rate in the horizontal direction (main shrinkage direction) small, but also the extension rate in the vertical direction (direction perpendicular to the main shrinkage direction) cannot be controlled to be low. This causes wrinkles and undulations in the mounting process due to heating.
[0065]
Reference Example 1
Each of the component (A) and the component (B) was mixed at a weight ratio shown in Tables 5 to 8, and the heat-shrinkable polyester film stretched at the stretching temperature and the stretching ratio shown in Tables 5 to 8 was examined for mounting properties. That is, using these, a cylindrical heat-shrinkable polyester film (folded diameter 113 mm, height 110 mm) is formed, and fitted into a glass bottle having a capacity of 330 ml (maximum diameter 70 mm, minimum diameter 50 mm, height 190 mm). , 3 m in length, 90 ° C. at inlet temperature, 95 ° C. at outlet temperature, attached by passing through the steam tunnel for 8 seconds, visually, the unevenness caused by shrinkage such as wrinkles, shrinkage spots and undulations The presence or absence was observed and evaluated according to the following criteria. (The test was performed three times for each sample.)
◎… No irregularities
…: Less than one unevenness per sample on average
△: There is an average of 1 or more and less than 2 irregularities per sample
×: Average of 2 or more irregularities per sample
The results are shown in Tables 5 to 8.
[0066]
[Table 5]

[0067]
[Table 6]

[0068]
[Table 7]

[0069]
[Table 8]

[0070]
As is clear from Tables 5 to 8, the heat-shrinkable polyester film of the present invention has a good appearance after mounting, and is superior to general polyester films. In particular, when the weight ratio of the copolyester A and the copolyester B is from 70:30 to 60:40, it is good, and the one stretched 3.8 times is the best.
[0071]
Reference Example 2
The components (A) and (B) were mixed at the weight ratios shown in Table 9 and the heat-shrinkable polyester film was uniaxially stretched under the conditions of a stretching ratio of 4.2 times and a stretching temperature of 85 ° C. Was examined. That is, two test pieces were cut from this film, the two were adhered with tetrahydrofuran, and allowed to stand at 23 ° C. for 24 hours, and then the 90 ° peel strength of both was measured over time and evaluated according to the following criteria.
…: The films do not peel off at the interface even when force is applied
Δ: The films are separated at the interface when force is applied
×: The films peel off at the interface without applying force.
Table 9 shows the results.
[0072]
[Table 9]

[0073]
As is clear from Table 9, the heat-shrinkable polyester film of the present invention exhibits excellent solvent sealing properties, and can be processed into a shape suitable for mounting on an object such as a bottle. It can be seen that the solvent sealability of the film is much improved. In particular, the solvent sealability is good when the weight ratio of the component (A) to the component (B) is from 80:20 to 60:40.
[0074]
【The invention's effect】
The heat-shrinkable polyester film of the present invention has a large limit value of shrinkage in the main shrinkage direction, is excellent in low-temperature shrinkage, has a reduced shrinkage speed, and has a substantial shrinkage in a direction perpendicular to the main shrinkage direction. , And gives a good finish free from shrinkage spots, wrinkles, and undulations to the stretched film. Furthermore, since it has excellent solvent sealing properties, it has good moldability. Therefore, it can be suitably used as a covering material, a bundling material, an exterior material, an electric insulating material, etc., particularly as a material for packaging materials, labels, and cap seals.

Claims (12)

(A) a copolymerized polyester composed of terephthalic acid units , 1,4-cyclohexanedimethanol units and ethylene glycol units, and (B) a terephthalic acid unit and 2-methyl-1,5-pentanediol unit or 3- to no weight ratio 40:60 and comprised copolymerized polyester and a-methyl-1,5-pentanediol units and ethylene glycol units 95: it consists copolyester composition comprising in a ratio of 5, and 100 ° C. hot water A heat-shrinkable polyester film having a shrinkage ratio of 40% or more in the main shrinkage direction when immersed in the film for 30 seconds , and a shrinkage ratio in a direction perpendicular to the main shrinkage direction of -5% to 5%. The molar ratio of the 1,4-cyclohexanedimethanol unit to the ethylene glycol unit in the diol unit of the component (A) is from 10:90 to 50:50, and 2-methyl-1,5 in the diol unit of the component (B) is used. The heat-shrinkable polyester film according to claim 1, wherein the molar ratio of -pentanediol unit or 3-methyl-1,5-pentanediol unit to ethylene glycol unit is from 5:95 to 35:65. Component (B) is a terephthalic acid unit, a 2-methyl-1,5-pentanediol unit or a 3-methyl-1,5-pentanediol unit and an ethylene glycol unit, and an aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms. 3. The heat-shrinkable polyester film according to claim 2, wherein the molar ratio of the terephthalic acid unit to the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms is 90:10 to 99.9: 0.1. The heat-shrinkable polyester film according to claim 3, wherein the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms constituting the component (B) is an adipic acid unit or a sebacic acid unit. (A) a copolymerized polyester composed of terephthalic acid units , 1,4-cyclohexanedimethanol units and ethylene glycol units, and (B) a terephthalic acid unit and 2-methyl-1,5-pentanediol unit or 3- to no weight ratio 40:60 and comprised copolymerized polyester and a-methyl-1,5-pentanediol units and ethylene glycol units 95: to form a film of the copolyester composition comprising in a ratio of 5, the resulting film The method for producing a heat-shrinkable polyester film according to claim 1, wherein the film is stretched 3 to 7 times in one direction. The molar ratio of the 1,4-cyclohexanedimethanol unit to the ethylene glycol unit in the diol unit of the component (A) is from 10:90 to 50:50, and 2-methyl-1,5 in the diol unit of the component (B) is used. The method for producing a heat-shrinkable polyester film according to claim 5, wherein the molar ratio of -pentanediol unit or 3-methyl-1,5-pentanediol unit to ethylene glycol unit is from 5:95 to 35:65. Component (B) is a terephthalic acid unit, a 2-methyl-1,5-pentanediol unit or a 3-methyl-1,5-pentanediol unit and an ethylene glycol unit, and an aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms. The heat-shrinkable polyester film according to claim 6, wherein the molar ratio of the terephthalic acid unit to the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms is from 90:10 to 99.9: 0.1. Method. The method for producing a heat-shrinkable polyester film according to claim 7, wherein the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms constituting the component (B) is an adipic acid unit or a sebacic acid unit. (A) a copolymerized polyester composed of terephthalic acid units , 1,4-cyclohexanedimethanol units and ethylene glycol units, and (B) a terephthalic acid unit and 2-methyl-1,5-pentanediol unit or 3- to no weight ratio 40:60 and comprised copolymerized polyester and a-methyl-1,5-pentanediol units and ethylene glycol units 95: copolyester composition comprising in a ratio of 5. The molar ratio of the 1,4-cyclohexanedimethanol unit to the ethylene glycol unit in the diol unit of the component (A) is from 10:90 to 50:50, and 2-methyl-1,5 in the diol unit of the component (B) is used. The copolymerized polyester composition according to claim 9, wherein the molar ratio of -pentanediol unit or 3-methyl-1,5-pentanediol unit to ethylene glycol unit is from 5:95 to 35:65. Component (B) is a terephthalic acid unit, a 2-methyl-1,5-pentanediol unit or a 3-methyl-1,5-pentanediol unit and an ethylene glycol unit, and an aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms. The copolymerized polyester composition according to claim 10, wherein the molar ratio of terephthalic acid units to aliphatic dicarboxylic acid units having 3 to 18 carbon atoms is from 90:10 to 99.9: 0.1. The copolymerized polyester composition according to claim 11, wherein the aliphatic dicarboxylic acid unit having 3 to 18 carbon atoms constituting the component (B) is an adipic acid unit or a sebacic acid unit.