JP2004243562A - Biaxially stretched laminated evoh film - Google Patents
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- JP2004243562A JP2004243562A JP2003033550A JP2003033550A JP2004243562A JP 2004243562 A JP2004243562 A JP 2004243562A JP 2003033550 A JP2003033550 A JP 2003033550A JP 2003033550 A JP2003033550 A JP 2003033550A JP 2004243562 A JP2004243562 A JP 2004243562A
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【０００１】
【発明の属する技術分野】
本発明は２軸延伸積層ＥＶＯＨフィルムに関し、より詳しくは、接着性樹脂層を介してＥＶＯＨ層の両面に炭化水素樹脂を含むポリプロピレン層が積層された２軸延伸積層ＥＶＯＨフィルムに関する。
【０００２】
【従来の技術】
ＥＶＯＨ（エチレン−酢酸ビニル共重合体ケン化物）フィルム、特に２軸延伸ＥＶＯＨフィルムは酸素透過度が小さく、保香性にも優れているが、吸湿するとこれらの特性が大幅に低下するという欠点がある。又、耐衝撃性に欠けるという欠点もある。
これらの欠点を解消するために、防湿性に優れ耐衝撃性にも優れるポリプロピレン層を積層することが考えられるが、この積層フィルムを高倍率で２軸延伸しようとすると、フィルムの破断、ＥＶＯＨ層の白化、フィブリル化、網状化等が発生し、良好な２軸延伸フィルムを得ることができない。
【０００３】
そこで良好な２軸延伸フィルムを得るための提案が種々なされている。その１つは、高エチレン含有量のＥＶＯＨを使用するものである（例えば、特許文献１参照）。
また、高エチレン含有量及び／又は低ケン化度のＥＶＯＨを低エチレン含有量高ケン化度のＥＶＯＨに混合して延伸性の改良を図るものもある（例えば、特許文献２、特許文献３参照）。
また、低融点のＥＶＯＨを高融点のＥＶＯＨに混合して延伸性の改良を図るものもある（例えば、特許文献４参照）。
また、ポリプロピレン層として高立体規則性、高結晶性のポリプロピレンを使用し、ＥＶＯＨ層として低融点のＥＶＯＨと高融点のＥＶＯＨとの混合物を使用して延伸性の改良を図るものもある（例えば、特許文献５参照）。
また、ＥＶＯＨ層は１軸延伸ではあるが、ポリプロピレン／炭化水素系樹脂含有ポリプロピレン層／ポリプロピレン層／接着性樹脂層／ＥＶＯＨ層／接着性樹脂層の構成とし、防湿性に優れる炭化水素系樹脂含有ポリプロピレン層を設けることによって酸素透過度を小さくするというものもある（例えば、特許文献６参照）。
【０００４】
【特許文献１】
特開平１−１５９２３２号公報（第３頁左上欄５〜７行）
【特許文献２】
特開平８−３１１２７６号公報（第３頁右欄２０〜２７行、実施例）
【特許文献３】
特開２００１−２７７３５２号公報（第３頁右欄２７〜４４行、実施例）
【特許文献４】
特開２０００−３１８０９５号公報（第３頁右欄２２〜３１行、第３頁右欄４８〜第４頁左欄４行、実施例）
【特許文献５】
特開２０００−３５１１８１号公報（第４頁右欄１９〜２６行、第５頁右欄４０〜４２行、第６頁左欄８〜２１行、実施例）
【特許文献６】
特開２０００−１６８００８号公報（請求項１、３、実施例）
【０００５】
【発明が解決しようとする課題】
しかしながら、前記の各提案は効果の点で未だ不十分であり、結局のところエチレン含有量の多いＥＶＯＨを使用せざるを得ないものであるので、得られた２軸延伸フィルムの酸素透過度が大きいという欠点を有す。
例えば、特許文献２の実施例のＥＶＯＨ層の厚さは約２μｍで、フィルムの酸素透過度は１０〜３０ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×６５％ＲＨ）である。
また、特許文献３の実施例では、ＥＶＯＨ層の厚さが５μｍであるフィルムの酸素透過度は３．０ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×５０％ＲＨ）、ＥＶＯＨ層の厚さが４μｍであるフィルムの酸素透過度は３．７〜４．１ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×５０％ＲＨ）、ＥＶＯＨ層の厚さが３μｍであるフィルムの酸素透過度は４．７ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×５０％ＲＨ）である（測定時の湿度が５０％ＲＨと低いことに注意。湿度が低いと酸素透過度は小さくなる）。
また、特許文献４の同時共押出成形の実施例では、ＥＶＯＨ層の厚さを２０μｍに換算したときのフィルムの酸素透過度は１．５〜２．９ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×８５％ＲＨ）である。
また、特許文献５の同時共押出成形の実施例では、ＥＶＯＨ層の厚さを２０μｍに換算したときのフィルムの酸素透過度は７〜２５ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×８５％ＲＨ）である。
また、特許文献６の実施例では、ＥＶＯＨ層の厚さが３μｍであるフィルムの酸素透過度は９．４ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×８０％ＲＨ）、ＥＶＯＨ層の厚さが４μｍであるフィルムの酸素透過度は９．０ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×８０％ＲＨ）、ＥＶＯＨ層の厚さが５μｍであるフィルムの酸素透過度は６．５ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×８０％ＲＨ）である。なお、特許文献１の実施例の延伸後の積層フィルム厚さは計算上０．３７〜０．６３μｍであり、とても製造することのできない薄さである。又、実施例で使用したＥＶＯＨがどのようなものであるかの記載もない。しかしながら、発明の詳細な説明にはエチレン含有量が少なくとも４５モル％のＥＶＯＨが好ましいとある。そこで４５モル％のＥＶＯＨを使用して製造可能な通常の厚さのフィルムを製造したとすれば、ＥＶＯＨの内容、延伸条件等から、その酸素透過度は特許文献４とほぼ同様の値になると推測される。
【０００６】
本発明の課題は、従来技術品よりも酸素透過度がさらに小さく、透明性（ヘーズ）に優れ、且つ、層間剥離強度に優れる２軸延伸積層ＥＶＯＨフィルムを提供することにある。
また本発明は、２軸延伸積層ＥＶＯＨフィルムにヒートシール性を付与することを課題とする。
さらに本発明は、２軸延伸積層ＥＶＯＨフィルムを用いた包装体を提供することを課題とする。
【０００７】
【課題を解決するための手段】
前記の課題を解決するため本発明は、炭化水素樹脂を含むポリプロピレン層（Ａ）と接着性樹脂層（Ｂ）とＥＶＯＨ層（Ｃ）とが（Ａ）／（Ｂ）／（Ｃ）／（Ｂ）／（Ａ）の順に積層された２軸延伸積層ＥＶＯＨフィルムであることを特徴とする。
また、ＥＶＯＨ層（Ｃ）の厚さを３μｍに換算したときの酸素透過度が２〜４ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×６５％ＲＨ）である２軸延伸積層ＥＶＯＨフィルムであることを特徴とする。
また、炭化水素樹脂を含むポリプロピレン層（Ａ）の少なくとも片面上に易ヒートシール性樹脂層（Ｄ）がさらに設けられた２軸延伸積層ＥＶＯＨフィルムであることを特徴とし、このフィルムを用いてなる包装体であることを特徴とする。
【０００８】
【発明の実施の形態】
本発明者らは前記の従来技術に係る欠点に鑑み鋭意研究の結果、ポリプロピレン層に炭化水素樹脂をブレンドすると、エチレン含有量が少なく、且つ、ケン化度が大きいＥＶＯＨであっても、驚くべきことに高倍率の２軸延伸積層ＥＶＯＨフィルムが低温延伸で良好に得られることを見出し、本発明を完成するに至った。
【０００９】
本発明のポリプロピレンとは、好ましくは１３Ｃ−ＮＭＲで測定したペンタッド分率（％ｍｍｍｍ）が９５％以上、より好ましくは９６％以上の高アイソタクチック構造を有するものである。ペンタッド分率（％ｍｍｍｍ）が９５％未満ではフィルムの剛性が劣る傾向にあるので、用途によっては好ましくない場合もある。
【００１０】
前記のポリプロピレンにブレンドされる炭化水素樹脂とは、脂肪族系炭化水素樹脂、芳香族系炭化水素樹脂、脂肪族−芳香族系炭化水素樹脂、脂環族系炭化水素樹脂、又はそれらの水素添加物等の一般に炭化水素樹脂と呼称されるもの（石油樹脂と呼称される場合もある）、あるいはロジン、ロジンエステル、テルペン樹脂等をいい、これらの中でも、脂環族系炭化水素樹脂の水素添加物が好ましく、特に軟化点が１２０℃以上のジシクロペンタジエン系炭化水素樹脂の水素添加物がより好ましい。
ポリプロピレンと炭化水素樹脂とのブレンド比は、重量比で、好ましくはポリプロピレン／炭化水素樹脂＝９５／５〜７０／３０、より好ましくはポリプロピレン／炭化水素樹脂＝９０／１０〜７５／２５、更に好ましくはポリプロピレン／炭化水素樹脂＝８２／１８〜７８／２２である。
ブレンド物に含まれる炭化水素樹脂が５重量％未満の場合、延伸性の改善効果が小さくなり、エチレン含有量の多いＥＶＯＨでないと高倍率の２軸延伸積層ＥＶＯＨフィルムが良好に得られない傾向にあり、従ってフィルムの酸素透過度が大きくなる傾向にある。一方、ブレンド物に含まれる炭化水素樹脂が３０重量％を超える場合、後記する易ヒートシール性樹脂層とのラミネート強度が弱くなり 好ましくない傾向にある。
【００１１】
本発明のＥＶＯＨ（エチレン−酢酸ビニル共重合体ケン化物）とは、エチレン含有量が好ましくは２６〜３６モル％、より好ましくは２８〜３４モル％、更に好ましくは２９〜３２モル％で、ケン化度が好ましくは９８％以上、より好ましくは９９％以上のものである。
エチレン含有量が２６モル％未満で且つケン化度が９８％以上のＥＶＯＨの場合、酸素透過度においてはより好ましいが、横延伸時にフィルムの破断が起こり易くなる傾向にある。
一方、エチレン含有量が３６モル％を超え且つケン化度が９８％以上のＥＶＯＨの場合、酸素透過度が大きくなり好ましくない傾向にある。
また、ケン化度が９８％未満のＥＶＯＨの場合、酸素透過度が大きくなり好ましくない傾向にある。
【００１２】
本発明の接着性樹脂とは、前記の炭化水素樹脂を含むポリプロピレン層とＥＶＯＨ層とを接着するものであれば特に限定するものではなく、例えば、酸変性ポリオレフィンが例示できる。好ましいのものとして無水マレイン酸変性ポリプロピレンが挙げられる。より好ましいものとしてホモポリプロピレン又はエチレン含有量が１重量％未満のプロピレン−エチレンランダム共重合体の無水マレイン酸変性物が挙げられ、融点が１５５℃以上のホモポリプロピレンの無水マレイン酸変性物が特に好ましいものとして挙げられる。
【００１３】
本発明のフィルムである、炭化水素樹脂を含むポリプロピレン層（Ａ）と接着性樹脂層（Ｂ）とＥＶＯＨ層（Ｃ）とが（Ａ）／（Ｂ）／（Ｃ）／（Ｂ）／（Ａ）の順に積層された２軸延伸積層ＥＶＯＨフィルムの各層の厚さは好ましくは、炭化水素樹脂を含むポリプロピレン層（Ａ）が２〜１５μｍ、接着性樹脂層（Ｂ）が１〜５μｍ、ＥＶＯＨ層（Ｃ）が１〜１０μｍである。そして、２軸延伸積層ＥＶＯＨフィルムのトータルの厚さは、好ましくは１０〜５０μｍである。
なお、各層には本発明の特性を損なわない範囲で、安定剤、滑剤、アンチブロッキング剤、帯電防止剤、紫外線吸収剤等の公知の添加剤やその他の樹脂を合目的的に添加してもよい。
【００１４】
次に２軸延伸積層ＥＶＯＨフィルムの好ましい製造方法について説明する。先ず５層の積層シートを作成する。この方法としては公知の如何なる方法を用いてもよいが、共押出によるのが簡便でより好ましい。次いで、このシートを縦方向に好ましくは１１０〜１２５℃で３〜５倍ロール延伸し、横方向に好ましくは１３０〜１４５℃で８〜１０倍テンター延伸し、熱固定し、必要ならフィルム表面にコロナ放電処理を施して、巻き取る。次いで、エージング後、所望の幅にスリットして、所期のフィルムが得られる。
なお、前記は逐次２軸延伸についてのものであるが、フラット状又はチューブ状のシートを同時２軸延伸してフィルムを得てもよい。
【００１５】
かくして得られた２軸延伸積層ＥＶＯＨフィルムの酸素透過度は、ＥＶＯＨ層（Ｃ）の厚さを３μｍに換算したとき、好ましくは２〜４ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×６５％ＲＨ）、より好ましくは２．５〜３．５ｃｃ／ｍ２・ｄａｙ・ａｔｍ（２０℃×６５％ＲＨ）である。
そして、フィルムのヘーズ値は２％以下と透明性に優れたものであり、炭化水素樹脂を含むポリプロピレン層（Ａ）とＥＶＯＨ層（Ｃ）との層間剥離強度は３５０ｇ／１５ｍｍ以上と優れたものである。
【００１６】
本発明のフィルムは、炭化水素樹脂を含むポリプロピレン層（Ａ）の少なくとも片面上に易ヒートシール性樹脂層（Ｄ）がさらに設けられた２軸延伸積層ＥＶＯＨフィルムとしてもよい。
このような構成にすると、ヒートシールにより合掌シール袋や三方シール袋のような包装用袋を作成することができる。また、易ヒートシール性樹脂を適宜選定することによって、各種容器の蓋材としても使用可能となる。そして、中味商品が入った包装体を得ることができる。
易ヒートシール性樹脂としては、特に限定するものではなく、例えば、ポリエチレン系樹脂やポリプロピレン系樹脂等のポリオレフィン、ポリスチレン、ポリエステル、ポリブタジエン、及びそれらのブレンド物が例示できる。
易ヒートシール性樹脂層（Ｄ）を設ける方法は公知の如何なる方法によってもよい。例えば、ドライラミ、押出しラミ、サンドラミ、コーティング等の方法が例示できる。
また、炭化水素樹脂を含むポリプロピレン層（Ａ）と易ヒートシール性樹脂層（Ｄ）との間に印刷層を設けてもよい。
【００１７】
【実施例】
次に代表的な実施例を比較例と共に挙げて説明する。
【００１８】
酸素透過度の測定は以下の方法によった。即ち、ＭＯＤＥＲＮ ＣＯＮＴＲＯＬ社製ＯＸ−ＴＲＡＮ ２００型を使用し、ＡＳＴＭ Ｄ ３９８５に準拠して測定した。
【００１９】
ヘーズ値の測定は以下の方法によった。即ち、日本電色工業株式会社製ＮＤＨ２０００を使用し、ＪＩＳ Ｋ ７１０５に準拠して測定した。
【００２０】
水蒸気透過度の測定は以下の方法によった。即ち、ＭＯＤＥＲＮ ＣＯＮＴＲＯＬ社製ＰＥＲＭＡＴＲＡＮ Ｗ−２００形を使用し、ＡＳＴＭ Ｆ ３７２−７３に準拠して測定した。
【００２１】
炭化水素樹脂を含むポリプロピレン層（Ａ）とＥＶＯＨ層（Ｃ）との層間剥離強度は以下の方法によった。即ち、試料を幅１５ｍｍに切り出し、１８０°剥離、引っ張り速度２００ｍｍ／ｍｉｎで測定した。
【００２２】
（実施例１）
ホモポリプロピレン（融点：１６０℃、ＭＦＲ（２３０℃、２１．１８Ｎ）：２．３、１３Ｃ−ＮＭＲで測定したペンタッド分率（％ｍｍｍｍ）：９６％）８０重量％とジシクロペンタジエン系炭化水素樹脂の水素添加物（トーネックス 株式会社製エスコレッツＥ５３２０、軟化点：１２５℃）２０重量％とのブレンド物からなる層（Ａ）と、ホモポリプロピレンの無水マレイン酸変性物（三井化学株式会社製ＱＦ５００、融点：１６５℃、ＭＦＲ（２３０℃、２１．１８Ｎ）：３）からなる層（Ｂ）と、ＥＶＯＨ（日本合成化学工業株式会社製 ＤＣ３２０３、エチレン含有量：３２モル％、ケン化度：９９％以上、融点：１８３℃、ＭＦＲ（２１０℃、２１．１８Ｎ）：４）からなる層（Ｃ）とが（Ａ）／（Ｂ）／（Ｃ）／（Ｂ）／（Ａ）の順に積層するようにして、温度２２０℃のＴダイから３種５層のシートを共押出し、２３℃の冷却ロールで引き取った。
次いでこのシートを、１１５℃で縦方向に３．４倍ロール延伸し、１３５℃で予熱し、１３５℃で横方向に９倍テンター延伸し、１６０℃で熱固定し、フィルムの片面を処理強度３０Ｗ／分・ｍ２でコロナ放電処理を施して、巻き取った。次いで、４０℃で２４時間エージングした後、所定の幅にスリットして所期の２軸延伸積層ＥＶＯＨフィルムを得た。各層の厚さは４μｍ／２μｍ／３μｍ／２μｍ／４μｍで、フィルムのトータルの厚さは１５μｍであった。
このフィルムの酸素透過度、ヘーズ値、水蒸気透過度、及び層間剥離強度を表１に示す。
【００２３】
（比較例１）
炭化水素樹脂をポリプロピレンにブレンドしない以外、実施例１と同様にして２軸延伸積層ＥＶＯＨフィルムを得ようとしたが、フィルムの破断が断続的に発生し、２軸延伸積層ＥＶＯＨフィルムを得ることができなかった。
【００２４】
（比較例２）
炭化水素樹脂をポリプロピレンにブレンドせず、且つ、予熱温度と横方向の延伸温度を共に１５５℃とした以外、実施例１と同様にして２軸延伸積層ＥＶＯＨフィルムを得た。
得られたフィルムは、網目状の無数の層間剥離部が存在しており、よく観察すると、その部分でＥＶＯＨ層の破断も観察された。
このフィルムの酸素透過度、ヘーズ値、水蒸気透過度、及び層間剥離強度を表１に示す。
【００２５】
【発明の効果】
本発明は以上のような構成からなるので、以下の効果を奏す。
【００２７】
本発明によれば、エチレン含有量が少なく、且つ、ケン化度が大きいＥＶＯＨであっても、高倍率の２軸延伸積層ＥＶＯＨフィルムが低温延伸で良好に得られる。従って、炭化水素樹脂の防湿効果と相まって、従来にない酸素透過度の小さい２軸延伸積層ＥＶＯＨフィルムが得られる。
【００２８】
また、炭化水素樹脂の防湿効果と相まって、水蒸気透過度の小さい２軸延伸積層ＥＶＯＨフィルムが得られる。
【００２９】
また、ヘーズ値の小さい（透明性に優れる）、層間剥離強度に優れる２軸延伸積層ＥＶＯＨフィルムが得られる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a biaxially stretched laminated EVOH film, and more particularly, to a biaxially stretched laminated EVOH film in which a polypropylene layer containing a hydrocarbon resin is laminated on both sides of an EVOH layer via an adhesive resin layer.
[0002]
[Prior art]
EVOH (saponified ethylene-vinyl acetate copolymer) films, particularly biaxially stretched EVOH films, have low oxygen permeability and excellent fragrance retention, but have the drawback that these properties are significantly reduced when moisture is absorbed. is there. In addition, there is a disadvantage that the impact resistance is lacking.
In order to solve these drawbacks, it is conceivable to laminate a polypropylene layer having excellent moisture resistance and excellent impact resistance. However, when this laminated film is to be biaxially stretched at a high magnification, the film breaks and the EVOH layer is removed. Whitening, fibrillation, reticulation, etc. occur, and a good biaxially stretched film cannot be obtained.
[0003]
Therefore, various proposals have been made for obtaining a good biaxially stretched film. One of them is to use EVOH having a high ethylene content (for example, see Patent Document 1).
In addition, there is a method in which EVOH having a high ethylene content and / or a low saponification degree is mixed with EVOH having a low ethylene content and a high saponification degree to improve stretchability (for example, see Patent Documents 2 and 3). ).
In addition, there is a method in which a low melting point EVOH is mixed with a high melting point EVOH to improve stretchability (for example, see Patent Document 4).
Further, there is also a method of using a highly stereoregular and highly crystalline polypropylene as a polypropylene layer and using a mixture of a low melting point EVOH and a high melting point EVOH as an EVOH layer to improve stretchability (for example, Patent Document 5).
Although the EVOH layer is uniaxially stretched, it has a structure of polypropylene / hydrocarbon resin-containing polypropylene layer / polypropylene layer / adhesive resin layer / EVOH layer / adhesive resin layer, and contains a hydrocarbon resin containing excellent moisture proof properties. There is a method in which the oxygen permeability is reduced by providing a polypropylene layer (for example, see Patent Document 6).
[0004]
[Patent Document 1]
JP-A-1-159232 (page 3, upper left column, lines 5-7)
[Patent Document 2]
JP-A-8-31276 (page 3, right column, lines 20 to 27, Example)
[Patent Document 3]
JP 2001-277352 A (page 3, right column, lines 27 to 44, Example)
[Patent Document 4]
JP 2000-318095 A (page 3 right column, lines 22 to 31, page 3 right column 48 to page 4, left column 4 lines, Example)
[Patent Document 5]
JP 2000-351181 A (page 4 right column, lines 19 to 26, page 5 right column, lines 40 to 42, page 6 left column, lines 8 to 21, examples)
[Patent Document 6]
Japanese Patent Application Laid-Open No. 2000-168008 (Claims 1, 3, Examples)
[0005]
[Problems to be solved by the invention]
However, each of the above proposals is still inadequate in terms of effect, and after all, EVOH having a high ethylene content must be used, so that the oxygen permeability of the obtained biaxially stretched film is low. It has the disadvantage of being large.
For example, in the example of Patent Document 2, the thickness of the EVOH layer is about 2 μm, and the oxygen permeability of the film is 10 to 30 cc / m 2 · day · atm (20 ° C. × 65% RH).
In the example of Patent Document 3, the oxygen permeability of a film having a thickness of the EVOH layer of 5 μm is 3.0 cc / m 2 · day · atm (20 ° C. × 50% RH), and the thickness of the EVOH layer is 5 μm. The oxygen permeability of the film having a thickness of 4 μm is 3.7 to 4.1 cc / m 2 · day · atm (20 ° C. × 50% RH), and the oxygen permeability of the film having a thickness of the EVOH layer of 3 μm is 4.7 cc. / M 2 · day · atm (20 ° C. × 50% RH) (note that the humidity at the time of measurement is as low as 50% RH. When the humidity is low, the oxygen permeability decreases).
In the example of co-extrusion molding of Patent Document 4, when the thickness of the EVOH layer is converted to 20 μm, the oxygen permeability of the film is 1.5 to 2.9 cc / m 2 · day · atm (20 ° C. × 85% RH).
In the co-extrusion molding example of Patent Document 5, when the thickness of the EVOH layer is converted to 20 μm, the oxygen permeability of the film is 7 to 25 cc / m 2 · day · atm (20 ° C. × 85% RH). ).
In the example of Patent Document 6, the film having an EVOH layer thickness of 3 μm has an oxygen permeability of 9.4 cc / m 2 · day · atm (20 ° C. × 80% RH), and the EVOH layer has a thickness of 3 μm. The oxygen permeability of the film having a thickness of 4 μm is 9.0 cc / m 2 · day · atm (20 ° C. × 80% RH), and the oxygen permeability of the film having a thickness of the EVOH layer of 5 μm is 6.5 cc / m 2 ···. day · atm (20 ° C. × 80% RH). The thickness of the laminated film after stretching in the example of Patent Document 1 is 0.37 to 0.63 μm, which is a thickness that cannot be produced very much. Also, there is no description of what the EVOH used in the examples was. However, the detailed description of the invention states that EVOH having an ethylene content of at least 45 mol% is preferred. Therefore, if a film having a normal thickness that can be manufactured by using 45 mol% of EVOH is manufactured, the oxygen permeability becomes substantially the same as that of Patent Document 4 from the contents of EVOH and stretching conditions. Guessed.
[0006]
It is an object of the present invention to provide a biaxially stretched laminated EVOH film having a smaller oxygen permeability, a higher transparency (haze), and a higher delamination strength than conventional products.
Another object of the present invention is to impart heat sealability to a biaxially stretched laminated EVOH film.
Still another object of the present invention is to provide a package using a biaxially stretched laminated EVOH film.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a polypropylene layer (A) containing a hydrocarbon resin, an adhesive resin layer (B), and an EVOH layer (C) comprising (A) / (B) / (C) / ( It is a biaxially stretched laminated EVOH film laminated in the order of B) / (A).
Further, a biaxially stretched laminated EVOH film having an oxygen permeability of 2 to 4 cc / m 2 · day · atm (20 ° C. × 65% RH) when the thickness of the EVOH layer (C) is converted to 3 μm. It is characterized by.
Further, it is a biaxially stretched laminated EVOH film further provided with an easily heat-sealable resin layer (D) on at least one surface of a polypropylene layer (A) containing a hydrocarbon resin, and is formed using this film. It is characterized by being a package.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have conducted intensive studies in view of the above-mentioned drawbacks of the prior art, and as a result of surprising research, when blending a hydrocarbon resin with a polypropylene layer, even if the EVOH has a low ethylene content and a high degree of saponification, it is surprising. In particular, they have found that a high-magnification biaxially stretched laminated EVOH film can be favorably obtained by low-temperature stretching, and have completed the present invention.
[0009]
The polypropylene of the present invention preferably has a high isotactic structure in which the pentad fraction (% mmmm) measured by 13 C-NMR is 95% or more, more preferably 96% or more. When the pentad fraction (% mmmm) is less than 95%, the rigidity of the film tends to be inferior, so that it may not be preferable depending on the use.
[0010]
The hydrocarbon resin blended with the polypropylene is an aliphatic hydrocarbon resin, an aromatic hydrocarbon resin, an aliphatic-aromatic hydrocarbon resin, an alicyclic hydrocarbon resin, or a hydrogenated resin thereof. Rosin, rosin ester, terpene resin, etc., which are generally referred to as hydrocarbon resins (sometimes referred to as petroleum resins), such as hydrogenated alicyclic hydrocarbon resins. In particular, a hydrogenated product of a dicyclopentadiene-based hydrocarbon resin having a softening point of 120 ° C. or more is more preferable.
The blend ratio of the polypropylene and the hydrocarbon resin is preferably a weight ratio of polypropylene / hydrocarbon resin = 95/5 to 70/30, more preferably polypropylene / hydrocarbon resin = 90/10 to 75/25, and still more preferably. Is polypropylene / hydrocarbon resin = 82/18 to 78/22.
When the amount of the hydrocarbon resin contained in the blend is less than 5% by weight, the effect of improving the stretchability is small, and a high-magnification biaxially stretched laminated EVOH film tends not to be favorably obtained unless the EVOH has a high ethylene content. And thus the oxygen permeability of the film tends to increase. On the other hand, when the amount of the hydrocarbon resin contained in the blend exceeds 30% by weight, the lamination strength with the easily heat-sealable resin layer described later tends to be weak, which is not preferable.
[0011]
The EVOH (ethylene-vinyl acetate copolymer saponified product) of the present invention is defined as having an ethylene content of preferably 26 to 36 mol%, more preferably 28 to 34 mol%, and still more preferably 29 to 32 mol%. The degree of conversion is preferably 98% or more, more preferably 99% or more.
In the case of EVOH having an ethylene content of less than 26 mol% and a saponification degree of 98% or more, although the oxygen permeability is more preferable, the film tends to be easily broken during transverse stretching.
On the other hand, in the case of EVOH having an ethylene content of more than 36 mol% and a degree of saponification of 98% or more, the oxygen permeability tends to increase, which is not preferable.
In the case of EVOH having a saponification degree of less than 98%, the oxygen permeability tends to increase, which tends to be undesirable.
[0012]
The adhesive resin of the present invention is not particularly limited as long as it bonds the polypropylene layer containing the hydrocarbon resin and the EVOH layer, and examples thereof include an acid-modified polyolefin. Preferred is maleic anhydride-modified polypropylene. More preferred are maleic anhydride-modified homopolypropylene or a propylene-ethylene random copolymer having an ethylene content of less than 1% by weight, and maleic anhydride-modified homopolypropylene having a melting point of 155 ° C. or higher is particularly preferred. Are listed.
[0013]
In the film of the present invention, the hydrocarbon resin-containing polypropylene layer (A), the adhesive resin layer (B), and the EVOH layer (C) are (A) / (B) / (C) / (B) / ( The thickness of each layer of the biaxially stretched laminated EVOH film laminated in the order of A) is preferably 2 to 15 μm for the polypropylene layer (A) containing a hydrocarbon resin, 1 to 5 μm for the adhesive resin layer (B), and EVOH. The layer (C) has a thickness of 1 to 10 μm. The total thickness of the biaxially stretched laminated EVOH film is preferably from 10 to 50 μm.
In addition, as long as the properties of the present invention are not impaired, a known additive such as a stabilizer, a lubricant, an antiblocking agent, an antistatic agent, and an ultraviolet absorber or other resins may be added to each layer. Good.
[0014]
Next, a preferred method for producing a biaxially stretched laminated EVOH film will be described. First, a five-layer laminated sheet is prepared. As this method, any known method may be used, but co-extrusion is simple and more preferable. Then, the sheet is roll-stretched in the longitudinal direction preferably at 110 to 125 ° C. by 3 to 5 times, and stretched in the transverse direction preferably by 10 to 10 times at 130 to 145 ° C., and heat-fixed. It is subjected to corona discharge treatment and wound up. Next, after aging, the film is slit to a desired width to obtain an intended film.
Although the above description is for the successive biaxial stretching, a film may be obtained by simultaneously biaxially stretching a flat or tubular sheet.
[0015]
The oxygen permeability of the biaxially stretched laminated EVOH film thus obtained is preferably 2 to 4 cc / m 2 · day · atm (20 ° C. × 65% RH) when the thickness of the EVOH layer (C) is converted to 3 μm. ), More preferably 2.5 to 3.5 cc / m 2 · day · atm (20 ° C. × 65% RH).
The haze value of the film is 2% or less, which is excellent in transparency, and the peeling strength between the polypropylene layer (A) containing the hydrocarbon resin and the EVOH layer (C) is as excellent as 350 g / 15 mm or more. It is.
[0016]
The film of the present invention may be a biaxially stretched laminated EVOH film in which a heat-sealable resin layer (D) is further provided on at least one surface of a polypropylene layer (A) containing a hydrocarbon resin.
With such a configuration, a packaging bag such as a gasket seal bag or a three-side seal bag can be prepared by heat sealing. In addition, by appropriately selecting the heat-sealable resin, the resin can be used as a cover material for various containers. Then, a package containing the content item can be obtained.
The heat-sealable resin is not particularly limited, and examples thereof include polyolefins such as polyethylene resins and polypropylene resins, polystyrenes, polyesters, polybutadienes, and blends thereof.
The method of providing the easily heat-sealable resin layer (D) may be any known method. For example, methods such as dry lamination, extrusion lamination, sand lamination, and coating can be exemplified.
Further, a printing layer may be provided between the polypropylene layer (A) containing the hydrocarbon resin and the easily heat-sealable resin layer (D).
[0017]
【Example】
Next, typical examples will be described together with comparative examples.
[0018]
The oxygen permeability was measured by the following method. That is, the measurement was performed according to ASTM D3985 using OX-TRAN 200 model manufactured by MODERN CONTROL.
[0019]
The haze value was measured by the following method. That is, it was measured according to JIS K 7105 using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.
[0020]
The measurement of the water vapor permeability was carried out by the following method. That is, the measurement was performed according to ASTM F372-73 using PERMATRAN W-200 manufactured by MODERN CONTROL.
[0021]
The delamination strength between the polypropylene layer (A) containing the hydrocarbon resin and the EVOH layer (C) was determined by the following method. That is, a sample was cut out to a width of 15 mm, peeled at 180 °, and measured at a pulling speed of 200 mm / min.
[0022]
(Example 1)
80% by weight of homopolypropylene (melting point: 160 ° C., MFR (230 ° C., 21.18N): 2.3, pentad fraction (% mmmm) measured by 13 C-NMR: 96%), and 80% by weight of dicyclopentadiene hydrocarbon A layer (A) composed of a blend of 20% by weight of a hydrogenated resin (Escolez E5320 manufactured by Tonex Corporation, softening point: 125 ° C.) and a maleic anhydride-modified homopolypropylene (QF500 manufactured by Mitsui Chemicals, Inc.) Melting point: 165 ° C, layer (B) composed of MFR (230 ° C, 21.18N): 3), EVOH (DC3203, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., ethylene content: 32 mol%, saponification degree: 99%) As described above, the layer (C) composed of the melting point: 183 ° C. and MFR (210 ° C., 21.18N): 4) is (A) / (B) / (C) / (B) / (A). ), Co-extruded five types of sheets from a T-die at a temperature of 220 ° C., and pulled out with a cooling roll at 23 ° C.
Next, the sheet is roll-stretched 3.4 times in the longitudinal direction at 115 ° C., preheated at 135 ° C., tenter-stretched in the transverse direction at 135 ° C., and heat-set at 160 ° C., and one side of the film is processed. Corona discharge treatment was performed at 30 W / min · m 2 , and the film was wound. Next, after aging at 40 ° C. for 24 hours, slitting was performed to a predetermined width to obtain an intended biaxially stretched laminated EVOH film. The thickness of each layer was 4 μm / 2 μm / 3 μm / 2 μm / 4 μm, and the total thickness of the film was 15 μm.
Table 1 shows the oxygen permeability, haze value, water vapor permeability, and delamination strength of this film.
[0023]
(Comparative Example 1)
An attempt was made to obtain a biaxially stretched laminated EVOH film in the same manner as in Example 1, except that the hydrocarbon resin was not blended with the polypropylene. could not.
[0024]
(Comparative Example 2)
A biaxially stretched laminated EVOH film was obtained in the same manner as in Example 1, except that the hydrocarbon resin was not blended with the polypropylene, and the preheating temperature and the transverse stretching temperature were both set to 155 ° C.
The obtained film had a myriad of network-like delaminated portions, and upon careful observation, breakage of the EVOH layer was also observed at those portions.
Table 1 shows the oxygen permeability, haze value, water vapor permeability, and delamination strength of this film.
[0025]
【The invention's effect】
Since the present invention has the above configuration, the following effects can be obtained.
[0027]
ADVANTAGE OF THE INVENTION According to this invention, even if it is EVOH which has a small ethylene content and a large saponification degree, a high-magnification biaxially stretched laminated EVOH film can be favorably obtained by low-temperature stretching. Accordingly, a biaxially stretched laminated EVOH film having a low oxygen permeability, which has not been obtained in the past, can be obtained in combination with the moisture-proof effect of the hydrocarbon resin.
[0028]
Further, in combination with the moisture-proof effect of the hydrocarbon resin, a biaxially stretched laminated EVOH film having a small water vapor permeability can be obtained.
[0029]
Further, a biaxially stretched laminated EVOH film having a small haze value (excellent in transparency) and excellent in delamination strength can be obtained.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003033550A JP4526770B2 (en) | 2003-02-12 | 2003-02-12 | Biaxially stretched EVOH film |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003033550A JP4526770B2 (en) | 2003-02-12 | 2003-02-12 | Biaxially stretched EVOH film |
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| JP4526770B2 JP4526770B2 (en) | 2010-08-18 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPWO2020196184A1 (en) * | 2019-03-22 | 2020-10-01 | ||
| US11512193B2 (en) | 2020-01-06 | 2022-11-29 | Inv Polypropylene, Llc | Polymeric substrate including a barrier layer |
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| JPS588644A (en) * | 1981-07-08 | 1983-01-18 | 住友ベークライト株式会社 | Heat-shrinkable multilayer film and its package |
| JPH01159232A (en) * | 1987-10-05 | 1989-06-22 | Mobil Oil Corp | Biaxial oriented multilayer barrier film and manufacture thereof |
| JP2000168008A (en) * | 1998-10-01 | 2000-06-20 | Nippon Synthetic Chem Ind Co Ltd:The | Laminate |
| JP2000351181A (en) * | 1999-06-11 | 2000-12-19 | Tohcello Co Ltd | Multilayered film |
| WO2001049487A1 (en) * | 1999-12-30 | 2001-07-12 | Mobil Oil Corporation | Multi-layer oriented polypropylene films with modified core layer |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS588644A (en) * | 1981-07-08 | 1983-01-18 | 住友ベークライト株式会社 | Heat-shrinkable multilayer film and its package |
| JPH01159232A (en) * | 1987-10-05 | 1989-06-22 | Mobil Oil Corp | Biaxial oriented multilayer barrier film and manufacture thereof |
| JP2000168008A (en) * | 1998-10-01 | 2000-06-20 | Nippon Synthetic Chem Ind Co Ltd:The | Laminate |
| JP2000351181A (en) * | 1999-06-11 | 2000-12-19 | Tohcello Co Ltd | Multilayered film |
| WO2001049487A1 (en) * | 1999-12-30 | 2001-07-12 | Mobil Oil Corporation | Multi-layer oriented polypropylene films with modified core layer |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPWO2020196184A1 (en) * | 2019-03-22 | 2020-10-01 | ||
| WO2020196184A1 (en) * | 2019-03-22 | 2020-10-01 | 三菱ケミカル株式会社 | Multilayer structure and stand-up pouch comprising same |
| EP3943297A4 (en) * | 2019-03-22 | 2022-04-20 | Mitsubishi Chemical Corporation | Multilayer structure, and stand-up pouch including the multilayer structure |
| US11738543B2 (en) | 2019-03-22 | 2023-08-29 | Mitsubishi Chemical Corporation | Multilayer structure, and standup pouch including the multilayer structure |
| JP7480702B2 (en) | 2019-03-22 | 2024-05-10 | 三菱ケミカル株式会社 | Multilayer structure and stand-up pouch containing same |
| US11512193B2 (en) | 2020-01-06 | 2022-11-29 | Inv Polypropylene, Llc | Polymeric substrate including a barrier layer |
| US11781000B2 (en) | 2020-01-06 | 2023-10-10 | Inv Polypropylene, Llc | Polymeric substrate including a barrier layer |
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| Publication number | Publication date |
|---|---|
| JP4526770B2 (en) | 2010-08-18 |
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