JP4384752B2 - Multilayer film - Google Patents

Description

【００２８】
ここで、プロピレン単位
【００２９】
【化２】

【００３０】
を┘と略記し、┘┘をｍ、┘┐をｒとしたときに、┘┘┘┘┘は、ｍｍｍｍで表され、上記式（Ａ）は、ｍｍｍｍｍｒで表される。なお、ｍはｍｅｓｏを、ｒはｒａｃｅｍｉを表わす。
【００３１】
この式で表されるポリピレン単位５連鎖（ｍｍｍｍ）中の３単位目のメチル基（例えば、上記式（Ａ）のＭｅ^３、Ｍｅ^４）に由来する^１３Ｃ−ＮＭＲスペクトルにおける吸収強度をＰｍｍｍｍとし、プロピレン単位中の全メチル基（Ｍｅ^１、Ｍｅ^２、Ｍｅ^３…）に由来する吸収強度をＰｗとすると、上記式（Ａ）で表される重合体の立体規則性は、ＰｍｍｍｍとＰｍの比、すなわち上記式（１）から求められる立体規則性指標の値［Ｍ５］で評価することができる。
【００３２】
本発明に用いられるポリプロピレン樹脂（Ｃ）の立体規則性指標の値［Ｍ５］は、沸騰ヘプタン不溶成分を^１３Ｃ−ＮＭＲで測定して求められる。
【００３３】
沸騰ヘプタン不溶成分の抽出法は、以下の通りである。ポリプロピレン樹脂３ｇと、２，６−ジ−ｔｅｒｔ−ブチル−４−メチルフェノール２０ｇと、ｎ−デカン５００ｍｌとを撹拌装置付きフラスコに入れ、１４５℃で加熱溶融させ、樹脂試料が溶解した後、室温までゆっくり冷却し、ついで２３℃の水浴上で８時間以上保持する。析出した重合体（２３℃、ｎ−デカン不溶成分）を含むｎ−デカン懸濁液をグラスフィルター（Ｇ−４) で濾過分離し、減圧乾燥した後、析出物を少なくとも６時間以上ヘプタンを用いてソックスレー抽出した後、乾燥して、沸騰ヘプタン不溶成分を得た。
【００３４】
得られた沸騰ヘプタン不溶成分の^１３Ｃ−ＮＭＲの測定法は、以下の通りである。沸騰ヘプタン不溶成分０．３５ｇをヘキサクロロブタジエン２．０ｍｌに溶解させ、グラスフィルター（Ｇ−２）で濾過した後、重水素化ベンゼン０．５ｍｌを加え、内径１０ｍｍのＮＭＲ測定用チューブに入れる。そして、日本電子製ＧＸ−５５０型ＮＭＲ測定装置を用い、１２０℃で^１３Ｃ−ＮＭＲ測定を行う。積算回数は、１０００回以上とした。立体規則性指標［Ｍ５］の値は、上記の測定によって得られる各々の構造に起因するピーク強度の積分値で求める。
【００３５】
ポリプロピレン樹脂（Ｃ）の立体規則性指標［Ｍ５］の値は、０．９５０〜０．９９５の範囲であり、０．９６０〜０．９９５が好ましく、０．９７０〜０．９９５がより好ましい。このような立体規則性指標［Ｍ５］の範囲を有するポリプロピレン樹脂（Ｂ）は、高結晶性である。立体規則性指標［Ｍ５］の値が０．９５０を下廻ると、高温での延伸が不可能となり低エチレン含量のＥＶＯＨを用いることができない。
【００３６】
さらに、ポリプロピレン樹脂（Ｃ）は、２３０℃、２１６０グラム荷重におけるＭＦＲが０．１〜１００グラム／１０分であり、１〜５０グラム／１０分であることが好ましく、２〜１０グラム／１０分であることがより好ましい。ポリプロピレン樹脂（Ｃ）のＭＦＲが０．１グラム／１０分未満となった場合、押出機にかかる負荷が大きくなり、また、１００グラム／１０分を超えた場合は層間に流れムラが生じ成形が困難となる。
【００３７】
上記の性質を有するポリプロピレン樹脂（Ｃ）は、高立体規則性、高結晶性のポリプロピレン樹脂であり、剛性が高く、高い熱変形温度、融点、結晶化温度を有するため優れた耐熱性を示す。そのため、ＥＶＯＨとの多層構造体を延伸する場合、高温での延伸が可能となり、これまで延伸不可能であった低エチレン含量のＥＶＯＨを用いても高倍率で延伸できる。
【００３８】
また、本発明の目的を阻害しない範囲でポリプロピレン樹脂（Ｃ）には、従来用いられている核剤、酸化防止剤、帯電防止剤、滑剤、ブロッキング防止剤、紫外線吸収剤、石油樹脂等が含まれてもよい。
【００３９】
核剤としては、例えば、ジベンジリデンソルビトール、ジメチルベンジリデンソルビトール等のソルビトール誘導体、ｐ−ｔｅｒｔ−ブチル安息香酸ナトリウム、ジ安息香酸アルミニウム等の芳香族カルボン酸のアルカリ金属塩またはアルミニウム塩、リン酸２，２−メチレンビス（４，６−ジ−ｔｅｒｔ−ブチルフェニル）ナトリウム等の芳香族リン酸エステルの金属塩に代表される有機系結晶核剤、タルク、マイカなどの無機系結晶化核剤、ポリシクロヘキセン、ポリシクロペンテン、ポリシクロブテン等の環状構造が側鎖に存在する分岐型環状重合体、ポリ３−メチル−１−ブテン、ポリ３−メチル−１−ペンテン、ポリ３−エチル−１−ペンテン、ポリ４−メチル−１−ペンテン等の炭素数３以上の分岐オレフィン重合体、ポリテトラフルオロエチレン等の含フッ素重合体等の高分子系結晶核剤などが挙げられる。
【００４０】
酸化防止剤としては、フェノール系ＢＨＴ、２，２’−メチレンビス（４−メチル−６−ｔ−ブチルフェノール）、２−ヒドロキシ−４−メトキシベンゾフェノン、２−ヒドロキシ−４−オクトキシベンゾフェノン、２，４−ジヒドロキシベンゾフェノン、２（２’−ヒドロキシ−５−メチルフェニル）ベンゾトリアゾール、置換ベンゾトリアゾール、２−エチルヘキシル−２−シアノ−３，３−ジフェニルアクリレート、エチル−２−シアノ−３，３−ジフェニルアクリレート、フェニルサルチレート、４−ｔ−ブチルフェニルサリチレート等が挙げられる。
【００４１】
帯電防止剤としては、アルキルアミンおよびその誘導体、高級アルコール、高級脂肪酸のグリセリンエステル類、ピリジン誘導体、硫酸化油、石鹸類、オレフィンの硫酸エステル塩類、アルキル硫酸エステル類、脂肪酸エチルスルフォン酸塩、アルキルスルフォン酸塩、アルキルナフタレンスルフォン酸塩、アルキルベンゼンスルフォン酸塩、ナフタレンスルフォン酸塩、琥珀酸エステルスルフォン酸塩、リン酸エステル塩、多価アルコールの部分的脂肪酸エステル、脂肪アルコールのエチレンオキサイド付加物、脂肪酸のエチレンオキサイド付加物、脂肪アミノまたは脂肪酸アミドのエチレンオキサイド付加物、アルキルフェノールのエチレンオキサイド付加物、アルキルナフトールのエチレンオキサイド付加物、多価アルコールの部分的脂肪酸エステルのエチレンオキサイド付加物、ポリエチレングリコール等が挙げられる。
【００４２】
滑剤としては、ステアリン酸、ステアリン酸アミド、オレイン酸アミド、高級アルコール、流動パラフィン等が挙げられる。
【００４３】
ブロッキング防止剤としては、合成シリカ、炭化カルシウム、非晶性アルミノシリケート、ゼオライト、ケイソウド土、タルク、長石、架橋ポリメチルメタクリレート等が挙げられる。
【００４４】
紫外線吸収剤としては、エチレン−２−シアノ−３，３’−ジフェニルアクリレート、２−（２’−ヒドロキシ−５’−メチルフェニル）ベンゾトリアゾール、２−（２’−ヒドロキシ−３’−ｔ−ブチル−５’−メチルフェニル）５−クロロベンゾトリアゾール、２−ヒドロキシ−４−メトキシベンゾフェノン、２、２’−ジヒドロキシ−４−メトキシベンゾフェノン、２−ヒドロキシ−４オクトキシベンゾフェノン等が挙げられる。
【００４５】
石油樹脂としては、Ｔｇ（ガラス転移温度）７０℃以上で水添率９９％以上のポリジシクロペンタジエン等の水素添加石油樹脂、あるいは極性基を実質的に含まないテルペン樹脂例えば、ピネン、ジペンテン、カレン、ミルセン、オシメン、リモネン、テレピレン、ザビネン、トリシクレン、ビサボレン、ジンギピレン、サンタレン、カンホレン、ミレン、トタレン等が挙げられる。
【００４６】
また、ポリプロピレン樹脂（Ｃ）は本発明の目的を阻害しない範囲で、本発明に用いるポリプロピレン樹脂（Ｃ）以外の、ポリプロピレンあるいはポリオレフィンを含んで用いても良い。さらに、ポリプロピレン樹脂（Ｃ）は、２種類以上の混合系で用いても良い。
【００４７】
本発明に用いられるＥＶＯＨ樹脂（Ａ）のエチレン含有量は約２０〜６０モル％で、ケン化度が約９０％以上である。
【００４８】
樹脂（Ａ）のエチレン含有量は約２０〜６０モル％であるが、約３５〜５０モル％であることが好ましい。エチレン含有量が約２０モル％を下廻る場合、ＰＰとの積層体の延伸を行うことが出来ない。一方、エチレン含有量が約６０モル％を上廻る場合、得られる多層延伸フィルムのバリアー性が充分でない。樹脂（Ａ）のエチレン含有量は約３７〜４８モル％であることがより好ましく、約４０〜４５モル％であることが最も好ましい。
【００４９】
樹脂（Ａ）のケン化度は約９０モル％以上であることが必要であり、約９５モル％以上であることがより好ましく、約９９モル％以上であることが最も好ましい。ケン化度をかかる範囲とすることが、得られる多層フィルムのバリアー性を維持する観点から好ましい。
【００５０】
なお、樹脂（Ａ）のエチレン含有量およびケン化度は、^１Ｈ−ＮＭＲによって、定量した値である。
【００５１】
更に樹脂（Ａ）が、融点の異なる少なくとも２種類以上のＥＶＯＨのブレンド物であることがより好ましい。
【００５２】
２種のＥＶＯＨを用いる場合、それぞれ、約１０〜９０重量％の含有量であることが好ましく、約２０〜８０重量％であることがより好ましく、約３０〜７０重量％含まれることが最も好ましい。
【００５３】
少なくとも２種類のＥＶＯＨがブレンドされている場合、熱分析、特にＤＳＣ解析において単一組成のＥＶＯＨと判別することができる。ブレンドされる２種類以上のＥＶＯＨの融点が大きく異なる場合は、ＤＳＣのピークが二本以上観測される。融点が近いＥＶＯＨをブレンドした場合には、見掛け上単一ピークになることがあるが、融点が一定値以上離れている場合には、ピークの形状がブロードなものとなる。ただし、単一ピークになる場合であっても、ＤＳＣの昇温速度を下げることにより、二本以上のピークもしくは主ピークに対し肩部のピークの存在を観測できる場合もある。
【００５４】
ＥＶＯＨの融点は、例えば、エチレン含量を変化させることにより調整される。エチレン含量が同じ場合には、ケン化度を変えることにより融点が調整される。
【００５５】
ブレンドしたＥＶＯＨ中のエチレンの全体としての含有量は、上記の通りであるが、ブレンドするＥＶＯＨのエチレン含有量の差は、好ましくは約３〜３０モル％であり、より好ましくは約３〜１５モル％である。
【００５６】
ブレンドしたＥＶＯＨのケン化度は、上記の通りであるが、ブレンドするＥＶＯＨのケン化度は、それぞれ、約９０モル％以上であることが好ましく、約９５モル％以上がより好ましく、約９９モル％以上が最も好ましい。
【００５７】
さらに、本発明においては、本発明のフィルムの延伸性、バリアー性を損なわない限り、上記ＥＶＯＨ樹脂に加えて、第三成分としてのＥＶＯＨをさらに添加することは自由である。
【００５８】
また、本発明に用いる樹脂（Ａ）の性能を阻害しない範囲であれば、ＥＶＯＨが少量のオレフィンとの共重合体であっても良い。共重合できる単量体の例としては、プロピレン、１−ブテン、イソブテン、４−メチル−１−ペンテン、１−ヘキセン、１−オクテンなどのα−オレフィンが挙げられる。
【００５９】
また、本発明に用いる樹脂（Ａ）の好適なＭＦＲ（２１０℃、２１６０グラム荷重下、ＪＩＳ Ｋ７２１０に基づく）は０．１〜１００グラム／１０分、より好適には０．５〜５０グラム／１０分である。
【００６０】
ＭＦＲが０．１グラム／１０分より小さいと、溶融成形が困難になり、溶液コート法によるフィルム化しかできなくなる虞があり、本発明における高倍率の延伸フィルムが得られない虞がある。一方、ＭＦＲが１００グラム／１０分を超えると、多層構造体を得た後の、高倍率での延伸が困難となる虞があるばかりでなく、得られた多層延伸フィルムの充分な強度が得られない虞もある。
【００６１】
また、本発明の目的を阻害しない範囲で熱安定剤、紫外線吸収剤、酸化防止剤、着色剤、フィラー、他の樹脂（ポリアミド、ポリオレフィンなど）、グリセリンやグリセリンモノステアレートなどの可塑剤を樹脂（Ａ）にブレンドすることもできる。
【００６２】
接着性樹脂（Ｂ）としては、商品名として、例えば、デュポン社製のＣＡＸ−３０３６、三井化学株式会社のアドマー、日本ポリオレフィン株式会社製のアドテックス、ＵＳＩ社のプレキサーなどが挙げられる。
【００６３】
これらのうちでも、ポリオレフィン系樹脂をベースとし、不飽和カルボン酸またはその無水物、エステル、アミドなどをグラフト重合したいわゆる酸変性ポリオレフィン樹脂を用いることが本発明においては好ましい。なかでも、ポリプロピレン樹脂をベースとする方が、より好ましい。不飽和カルボン酸としては、アクリル酸、メタクリル酸、マレイン酸、フマル酸、イタコン酸などが挙げられる。
【００６４】
接着性樹脂（Ｂ）の２３０℃、２１６０グラム荷重におけるＭＦＲは、約１〜５０グラム／１０分であることが好ましく、約２〜１０グラム／１０分であることがより好ましい。接着性樹脂（ｂ）が約１グラム／１０分に満たないと、押出機にかかる負荷が大きくなる虞があり、また、約５０グラム／１０分を超えると層間に流れムラが生じ成形が困難となる虞がある。
【００６５】
本発明の多層フィルムは、ＥＶＯＨ（Ａ）層および高結晶性ＰＰ樹脂（Ｃ）層が接着性樹脂（Ｂ）層を介して積層されてなる多層構造体を延伸してなるものであり、高結晶性ＰＰ層は少なくとも１軸、好ましくは２軸配向した状態にある。
【００６６】
多層構造体の具体的な層構成としては、ＰＰ樹脂（Ｃ）をＣ、接着性樹脂（Ｂ）をＢ、ＥＶＯＨ樹脂（Ａ）をＡとして表すと、Ｃ／Ｂ／Ａ／Ｂ／Ｃの５層構造、Ｃ／Ｂ／Ａ／Ｂの４層構造あるいはＣ／Ｂ／Ａの３層構造等であるが、特に限定されるのもではない。また、これらの層に加えて、ヒートシール性、帯電防止性、防湿性などの機能性を付与する層を設けることもできる。
【００６７】
ヒートシール性を付与するには、片面もしくは両面の最外層のＰＰにもう１層のヒートシール層を設けることができる。すなわち、ヒートシール性樹脂層をＨで表すと、Ｈ／Ｃ／Ｂ／Ａ／Ｂ／Ｃ、Ｈ／Ｃ／Ｂ／Ａ／Ｂ／Ｃ／Ｈ、Ｈ／Ｃ／Ｂ／Ａ／Ｂ、Ｈ／Ｃ／Ｂ／Ａ／Ｂ／Ｈ、Ｈ／Ｃ／Ｂ／Ａなどの層構成を挙げることができる。また、ヒートシール性樹脂としては、プロピレンと炭素数４以上のα−オレフィンとのランダム共重合体または、プロピレンと炭素数４以上のα−オレフィンとエチレンのランダム共重合体、ポリエチレン、エチレンビニルアセテート（ＥＶＡ）等が挙げられる。
【００６８】
静電防止性を付与するには、少なくとも１つのＰＰ層に前記に挙げた帯電防止剤を１類または２種類以上の混合系で添加し、添加したＰＰ層をコロナ処理等の表面処理を行う。また、少なくとも片面の最外層に、静電防止剤が添加された溶液をコートする方法もある。
【００６９】
防湿性を付与するには、少なくとも１つのＰＰ層に前記に挙げた石油樹脂あるいは極性基を実質的に含まないテルペン樹脂を１種類または２種類以上添加する。
【００７０】
また、上記層構成には、必要に応じて回収（Ｒｅｇ）層を設けることもできる。かかる回収層を別途設けても良いし、本発明におけるＰＰ層、もしくは接着性樹脂層に回収物を加え、実質的に回収層とすることもできる。具体的な層構成の例としては、Ｒｅｇ／Ｃ／Ｂ／Ａ／Ｂ／Ｃ、Ｒｅｇ／Ｃ／Ｂ／Ａ／Ｂ／Ｃ／Ｒｅｇ、Ｃ／Ｒｅｇ／Ｂ／Ａ／Ｂ／Ｃ、Ｃ／Ｒｅｇ／Ｂ／Ａ／Ｂ／Ｒｅｇ／Ｃ、Ｒｅｇ／Ｃ／Ｂ／Ａ／Ｂ、Ｃ／Ｒｅｇ／Ｂ／Ａ／Ｂ、Ｒｅｇ／Ｃ／Ｂ／Ａ、Ｃ／Ｒｅｇ／Ｂ／Ａ等を挙げることが出来るがこれに限定されるものではない。
【００７１】
また、印刷およびラミネートを行うためにフィルム表面にコロナ放電処理やフレーム処理を行うこともできる。
【００７２】
延伸後の多層延伸フィルムの厚みは、全体の厚みで約１０μｍ以上が好ましい。約１５〜１００μｍがより好ましく、約１５〜５０μｍがさらに好ましい。
【００７３】
接着性樹脂（Ｂ）の層厚みは約０．５〜５０μｍが好ましく、約２〜２０μｍがより好ましく、３〜１０μｍがさらに好ましい。接着性樹脂（Ｂ）が０．５μｍ未満であるとＰＰ（Ｃ）層とＥＶＯＨ（Ａ）層の層間接着性が充分でなくなり、目的の多層フィルムを得ることができなくなる虞がある。５０μｍを超えるとコストが高くなる。
【００７４】
また、ＥＶＯＨ（Ａ）層は約１〜２０μｍが好ましく、約４〜９μｍがさらに好ましい。ＥＶＯＨ（Ａ）層が約１μｍ未満の場合、目的のバリア性が得られにくくなり、２０μｍ以上では得られた延伸フィルムの剛性が劣る場合がある。
【００７５】
更にＰＰ（Ｃ）層の層厚みは約５〜９５μｍが好ましく、約８〜５０μｍがより好ましく、約１０〜３０μｍがさらに好ましい。
【００７６】
Ｒｅｇ層を設ける場合、Ｒｅｇ層の厚みは特に限定されない。
【００７７】
延伸前の多層構造体の製造方法は、ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）、ＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内で、例えば、Ｃ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し共押出し、５０℃以下好ましくは４０℃以下の冷却ロール上にキャストし多層構造体を作成する。
【００７８】
ＰＰとＥＶＯＨの多層積層構造体を延伸する方法として、一般的な製造法である、逐次二軸延伸法あるいは同時二軸延伸法が挙げられる。
【００７９】
逐次二軸延伸法で延伸する場合、例えば、ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）およびＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し、共押出し、冷却ロール上にキャストし、積層シートを作成する。ついで、機械方向にロール延伸した後、テンターにて横方向に延伸して目的の多層フィルムを製造する。
【００８０】
また、ＰＰ樹脂（Ｃ）と接着性樹脂（Ｂ）を別々の押出機より押出しダイス内でＰＰ／接着性樹脂となるよう積層し共押出し、冷却ロール上にキャストし積層シートを作成する。ついで、機械方向に延伸した後、別の押出機よりＥＶＯＨ（Ａ）層、またはＥＶＯＨ（Ａ）層を含む多層構造体を押出し接着層上に押出ラミネーションした後、テンターにて横方向に延伸して目的の多層フィルムを製造することもできる。
【００８１】
さらに、ＰＰ樹脂（Ｃ）を押出し機により押出し、冷却ロール上にキャストしシートを作成する。ついで、機械方向に延伸した後、別の押出機より接着性樹脂（Ｂ）層とＥＶＯＨ（Ａ）層とを含む多層構造体を押出し、ＰＰ（Ｃ）層上に（Ｂ）層がくるように押出ラミネーションした後、テンターにて横方向に延伸して目的の多層フィルムを製造することもできる。
【００８２】
同時二軸延伸法としては、例えば、ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）およびＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し、円筒ダイスより共押出し、チューブ状の積層体を作成する。ついで、機械方向、横方向同時に延伸して目的の多層フィルムを製造する。
【００８３】
また、例えば、ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）およびＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し、共押出し、冷却ロール上にキャストし多層構造体を作成する。ついで、テンターにて機械方向、横方向同時に延伸して目的の多層フィルムを製造することもできる。
【００８４】
なお、ここで示した層構成は、一例であり特に限定されるのもではない。
【００８５】
以下、本発明の多層フィルムを得る好ましい製造方法について説明する。
【００８６】
第１の方法として、同時共押出成形物の逐次二軸延伸を説明する。ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）およびＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内で、例えば、Ｃ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し、共押出し、約５０℃以下、好ましくは約４０℃以下の冷却ロール上にキャストし多層構造体を作成する。ついで、約１００〜１４０℃、好ましくは、約１１０〜１３０℃で機械方向に約４〜７倍好ましくは約５〜６倍に延伸した後、予熱温度が約１８０〜２００℃、好ましくは約１８５〜１９５℃で加熱し、約１６０〜１７５℃、好ましくは約１６５〜１７０℃で横方向に約７〜１２倍、好ましくは約８〜１０倍に延伸して目的の多層フィルムを製造することができる。
【００８７】
第２の方法として、押出コーティングを用いた逐次二軸延伸法を説明する。ＰＰ樹脂（Ｃ）と接着性樹脂（Ｂ）とを別々の押出機より押出しダイス内で、例えば、Ｃ／Ｂとなるよう積層し共押出し、約５０℃以下、好ましくは約４０℃以下の冷却ロール上にキャストし、多層構造体を作成する。ついで、約１００〜１４０℃好ましくは約１１０〜１３０℃で機械方向に約４〜７倍好ましくは約５〜６倍に延伸した後、別の押出機より、例えば、ＥＶＯＨを押出し、接着層上に押出ラミネーションした後、予熱温度が約１８０〜２００℃、好ましくは約１８５〜１９５℃で加熱し、約１６０〜１７５℃、好ましくは約１６５〜１７０℃で横方向に約７〜１２倍、好ましくは約８〜１０倍に延伸して、目的の多層フィルムを製造することができる。
【００８８】
第３の方法として、同時二軸延伸法を説明する。すなわち、ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）、ＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内で、例えば、Ｃ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し、円筒ダイスより共押出し、約５０℃以下、好ましくは約４０℃以下の冷却水で冷却し、チューブ状の積層体を作成する。ついで、環状赤外線ヒーター用い加熱した後、加圧空気を送り込んだバブル状で機械方向に約４〜７倍好ましくは約５〜６倍、横方向に約４〜７倍、好ましくは約５〜６倍、同時に延伸して目的の多層フィルムを製造することができる。
【００８９】
第４の方法として、テンター法を用いた同時二軸延伸を説明する。すなわち、ＰＰ樹脂（Ｃ）、接着性樹脂（Ｂ）、ＥＶＯＨ樹脂（Ａ）を別々の押出機より押出しダイス内で、例えば、Ｃ／Ｂ／Ａ／Ｂ／Ｃとなるよう積層し、共押出し、約５０℃以下好ましくは約４０℃以下の冷却ロール上にキャストし多層構造体を作成する。ついで、テンター内にて、予熱温度が約１８０〜２００℃好ましくは約１８５〜１９５℃で加熱し、約１６０〜１７５℃好ましくは約１６５〜１７０℃で機械方向に約４〜１２倍好ましくは約５〜１０倍、横方向に約４〜１２倍好ましくは約５〜１０倍同時に延伸して目的の多層フィルムを製造することができる。
【００９０】
こうして得られた、多層フィルムは、機械的強度、ガスバリアー性に優れ、コストメリットもある。よって、ガスバリアー性を要求される包装分野において広く用いることが可能となった。特に本発明の多層フィルムは燃やしたときに有害ガスを発生しないので、その点からも食品包装をはじめ医薬等幅広い用途で使用可能なものである。
【００９１】
【実施例】
以下、実施例により本発明をさらに説明するが、本発明は、これにより何ら限定されるものではない。
【００９２】
各実施例におけるＰＰ樹脂（Ｃ）の立体規則性指数［Ｍ５］は、上記方法に従って、沸騰ヘプタン不溶成分を抽出し、^１３Ｃ−ＮＭＲを測定して求めた。
【００９３】
多層構造体、多層フィルムの評価は、以下の方法に従った。
【００９４】
（１）延伸性（同時共押出成形の場合）
延伸時の切断状況および作成した多層フィルムの状態を目視にて評価し、３段階で表した。
○： 延伸可能であった。
△： 一部延伸ムラが見られたが、延伸可能であった。
×： 延伸不可能であった（切断した。）。
【００９５】
（２）延伸性（押出コーティングの場合）
延伸時の切断状況および作成した多層フィルムの状態を目視にて評価し、３段階で表した。
○： 延伸可能であった。
△： 一部延伸ムラが見られたが、延伸可能であった。
×： 延伸不可能であった。
【００９６】
（３）フィルムの外観
作成した多層フィルムの状態を目視、およびフィルムのヘイズを測定し評価した。
【００９７】
目視による評価以下の３段階で表した。
○： 透明であった。
△： すりガラス状（マット調）であった。
×： 網目状であった。
【００９８】
ヘイズ値の測定は、ＪＩＳ Ｋ７１５０に記載の方法に準じて日本電色工業株式会社製のヘイズメーター３００Ａを用いた。値は、フィルム４枚を重ね合わせて測定したものである。
【００９９】
（４）酸素透過度
ＭＯＤＥＲＮ ＣＯＮＴＲＯＬＳ ＩＮＣ．製酸素透過量測定装置ＭＯＣＯＮＯＸ−ＴＲＡＮ２／２０型を用い、２０℃、８５％ＲＨ、および９５％ＲＨの高湿度条件でＪＩＳ Ｋ７１２６（等圧法）に記載の方法に準じて測定した。評価したサンプルは、Ｃ／Ｂ／Ａ／Ｂ／Ｃ構成の延伸フィルムの場合は５×１０倍、Ｃ／Ｂ／Ａ構成の延伸フィルムの場合は１１倍に延伸されたものである。なお、本発明でいう酸素透過度は、Ｃ／Ｂ／Ａ／Ｂ／Ｃ構成またはＣ／Ｂ／Ａ構成の延伸フィルムについて、任意のＥＶＯＨ膜厚で測定した酸素透過量（ｍｌ／ｍ^２・ｄａｙ・ａｔｍ）を、ＥＶＯＨ層の厚み２０μｍでの酸素透過量に換算した値（ｍｌ・２０μｍ／ｍ^２・ｄａｙ・ａｔｍ）である。
【０１００】
実施例１
エチレン含有量４７モル％、ケン化度９９．６％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２ｇ／１０分(２１０℃、２１６０ｇ荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６．０ｇ／１０分（２１０℃、２１６０ｇ荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃ構成となるよう積層し、共押出し、３５℃の冷却ロール上にキャストし、積層シートを作成した。ついで、１２０℃で機械方向に５〜６倍に延伸した後、予熱温度１８５℃で加熱し、１６５℃で横方向に８〜１０倍延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１０１】
実施例２
エチレン含量４４モル％、ケン化度９９．５％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃ構成となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、１２０℃で機械方向に５〜６倍に延伸した後、予熱温度が１９０℃で加熱し、１７０℃で横方向に８〜１０倍延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１０２】
実施例３
下記の２種のＥＶＯＨ樹脂ａ１およびａ２：
ＥＶＯＨ樹脂ａ１；エチレン含有量３８モル％、ケン化度９９．６％、ＭＦＲ３．８ｇ／１０分（２１０℃、２１６０ｇ）、融点１７５℃であり、リン化合物（リン酸二水素カリウム）をリン元素換算で１００ｐｐｍ、ナトリウム塩（酢酸ナトリウム）をナトリウム元素換算で５０ｐｐｍ含有している；
ＥＶＯＨ樹脂ａ２；エチレン含有量４８モル％、ケン化度９９．６％、ＭＦＲ３３ｇ／１０分（２１０℃、２１６０ｇ）、融点１６０℃であり、リン化合物（リン酸二水素カリウム）をリン元素換算で５０ｐｐｍ含有している；
をそれぞれ５０重量部づつドライブレンドした後、直径４０ｍｍ、Ｌ／Ｄ＝２４、圧縮比３．８のマドック型混練部を有するスクリューで溶融押出し、樹脂組成物のペレットを得た。得られたＥＶＯＨ（Ａ）は、エチレン含量４３モル％、ケン化度９９．６％、ＭＦＲ＝７．７グラム／１０分（２１０℃、２１６０グラム荷重）であった。
【０１０３】
このＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、１２０℃で機械方向に５〜６倍に延伸した後、予熱温度が１９５℃で加熱し、１７０℃で横方向に８〜１０倍延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１０４】
実施例４
立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内で高結晶性ポリプロピレン／接着性樹脂となるよう積層し共押出し、３５℃以下の冷却ロール上にキャストし積層シートを作成した。ついで、１１５℃で機械方向に５〜６倍に延伸した後、別の押出機よりエチレン含有量４７モル％、ケン化度９９．６％、ＭＦＲ＝３３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）を押出し、接着層上に押出ラミネーションした後、予熱温度が１８５℃で加熱し、１６５℃で横方向に８〜１０倍延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表２に示す。
【０１０５】
実施例５
立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内で高結晶性ポリプロピレン／接着性樹脂となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、１１５℃で機械方向に５〜６倍に延伸した後、別の押出機よりエチレン含量４４モル％、ケン化度９９．５％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）を押出し接着層上に押出ラミネーションした後、予熱温度が１９０℃で加熱し、１７０℃で横方向に８〜１０倍延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表２に示す。
【０１０６】
実施例６
立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内で高結晶性ポリプロピレン／接着性樹脂となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、１１５℃で機械方向に５〜６倍に延伸した後、実施例３で調製した、２種のＥＶＯＨをブレンドして得られたＥＶＯＨ（Ａ）を別の押出機より押出し接着層上に押出ラミネーションした後、予熱温度が１９５℃で加熱し、１７０℃で横方向に８〜１０倍延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表２に示す。
【０１０７】
実施例７
エチレン含有量４７モル％、ケン化度９９．６％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６．０グラム／１０分（２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し、円筒状のダイスより共押出し、３０℃の冷却水で冷却しチューブ状の積層体を作成した。ついで、環状赤外線ヒーターの設定温度を３８０℃で加熱した後、加圧空気を送り込んだバブル状で機械方向に５．０〜６．０倍、横方５．０〜６．０倍同時に延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１０８】
実施例８
エチレン含量４４モル％、ケン化度９９．５％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し円筒ダイスより共押出し、３０℃の冷却水で冷却しチューブ状の積層体を作成した。ついで、環状赤外線ヒーターの設定温度を３９０℃で加熱した後、加圧空気を送り込んだバブル状で機械方向に５．０〜６．０倍、横方５．０〜６．０倍同時に延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１０９】
実施例９
実施例３で調製した、２種のＥＶＯＨをブレンドして得られたＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し円筒ダイスより共押出し、３０℃の冷却水で冷却しチューブ状の積層体を作成した。ついで、環状赤外線ヒーターの設定温度を４００℃で加熱した後、加圧空気を送り込んだバブル状で機械方向に５．０〜６．０倍、横方５．０〜６．０倍同時に延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１１０】
実施例１０
エチレン含有量４７モル％、ケン化度９９．６％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６．０グラム／１０分（２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、テンター内にて、予熱温度が１８５℃で加熱し、１６５℃で機械方向に５〜６倍、横方向に９〜１０倍同時に延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１１１】
実施例１１
エチレン含量４４モル％、ケン化度９９．５％、ＭＦＲ＝１３グラム／１０分（２１０℃、２１６０グラム荷重）であるＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、テンター内にて、予熱温度が１９０℃で加熱し、１７０℃で機械方向に５〜６倍、横方向に９〜１０倍同時に延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１１２】
実施例１２
実施例３で調製した、２種のＥＶＯＨをブレンドして得られたＥＶＯＨ（Ａ）と、立体規則性指数[Ｍ５]＝０．９８、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）、ＭＦＲ＝６グラム／１０分(２１０℃、２１６０グラム荷重)である無水マレイン酸変性ポリプロピレン樹脂（Ｂ）を別々の押出機より押出しダイス内でＣ／Ｂ／Ａ／Ｂ／Ｃの構成となるよう積層し共押出し、３５℃の冷却ロール上にキャストし積層シートを作成した。ついで、テンター内にて、予熱温度が１９５℃で加熱し、１７０℃で機械方向に５〜６倍、横方向に９〜１０倍同時に延伸して目的の多層フィルムを製造した後、上記の評価項目に記載した評価を行った。得られた結果を表１に示す。
【０１１３】
比較例１
実施例１において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１１４】
比較例２
実施例２において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１１５】
比較例３
実施例３において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１１６】
比較例４
実施例４において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例４と同様に評価を行った。その結果を表２に示す。
【０１１７】
比較例５
実施例５において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)である高結晶性ポリプロピレン（Ｃ）を用いた以外は、実施例４と同様に評価を行った。その結果を表２に示す。
【０１１８】
比較例６
実施例６において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例４と同様に評価を行った。その結果を表２に示す。
【０１１９】
比較例７
実施例７において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１２０】
比較例８
実施例８において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１２１】
比較例９
実施例９において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１２２】
比較例１０
実施例１０において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１２３】
比較例１１
実施例１１において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１２４】
比較例１２
実施例１２において、高結晶性ポリプロピレン（Ｃ）の代わりに立体規則性指数[Ｍ５]＝０．９２、ＭＦＲ＝２グラム／１０分(２１０℃、２１６０グラム荷重)であるポリプロピレン（Ｃ）を用いた以外は、実施例１と同様に評価を行った。その結果を表１に示す。
【０１２５】
【表１】

【０１２６】
【表２】

【０１２７】
立体規則性指数[Ｍ５]が特定範囲にあるポリプロピレンを用いて得られた実施例のフィルムは、延伸性に優れるとともに、高湿度下におけるガスバリアー性も高く保持されていた。また、外観も透明性も優れていた。これに対して、立体規則性指数[Ｍ５]が特定範囲外のポリプロピレンを用いて得られた比較例のフィルムは、延伸性が悪く成形不良であった。また、外観も透明性も悪かった。
【０１２８】
【発明の効果】
立体規則性指数[Ｍ５]とＭＦＲが特定範囲にあるポリプロピレンと、エチレン含量とケン化度が特定範囲のＥＶＯＨとを用いて得られた多層フィルムは、延伸性に優れるとともに、高湿度下におけるガスバリアー性も高く保持されており、外観も透明性も優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention provides a gas barrier property obtained by stretching a multilayer structure in which a resin layer made of an ethylene-vinyl alcohol copolymer and a polypropylene resin layer are laminated via an adhesive resin layer at least in a uniaxial direction at a high magnification. In particular, the present invention relates to a stretched multilayer film excellent in gas barrier properties, fragrance retention and transparency under high humidity.
[0002]
[Prior art]
In general, polypropylene resin (hereinafter sometimes abbreviated as PP) is easy to be stretched and molded, and is excellent in mechanical properties and appearance of molded products. ing. However, a disadvantage of PP is that gas barrier properties are poor.
[0003]
On the other hand, an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) film is a food, pharmaceutical, etc., taking advantage of its excellent barrier properties, transparency and oil resistance against oxygen, carbon dioxide and nitrogen. Used as packaging material. However, the EVOH film has a drawback that the barrier property is greatly affected by humidity, so that the barrier property is lowered under high humidity, and the impact strength is inferior.
[0004]
Therefore, in order to compensate for the disadvantages of PP having low gas barrier properties and the moisture resistance and impact resistance of EVOH being poor, polyolefins having excellent moisture resistance and impact resistance, such as PP, and EVOH having excellent gas barrier properties. In general, EVOH has a very poor stretchability compared to PP. Therefore, in the production of a multilayer film composed of a laminate of PP and EVOH, it is sufficient to stretch EVOH. Various ingenuity has been made to give sex.
[0005]
For example, Japanese Patent No. 2679823 (US Pat. No. 4,880,706) describes a multilayer barrier film using EVOH and PP from a multilayer structure having a structure of PP layer / adhesive layer / EVOH layer / adhesive layer / PP layer. A biaxially stretched film is disclosed. This biaxially stretched film is rapidly cooled to around 50 ° C. immediately after forming a multilayer structure (multi-layer coextruded film), and after preheating in the range of 135 to 150 ° C. The film is stretched 4 to 7 times in the longitudinal direction and then preheated in the range of 170 to 180 ° C. and then stretched 7 to 10 times in the lateral direction in the range of 155 to 165 ° C. EVOH having an ethylene content of 45 mol% or more, a hydrolysis degree of 99% or more, 190 ° C., and EVOH melt flow rate (hereinafter referred to as MFR) of 14-18 g / 10 min at 190 ° C. It is preferably used. As polyolefin used by laminating | stacking, PP of MFR 2-6g / 10min is described.
[0006]
Further, for example, in JP-A-60-187538 (US Pat. No. 4,561,920), EVOH having an MFR of at least about 8 grams / 10 minutes is suitable, and a multilayer structure containing this EVOH is crystallized from EVOH. It cools rapidly so that the degree does not exceed about 25%.
[0007]
In any of the above documents, EVOH having a specific range of MFR or EVOH having a high ethylene content is used in order to give EVOH sufficient stretchability, so it can be said that the gas barrier property is not necessarily high. Absent.
[0008]
Thus, since the stretchability of EVOH is poor, when stretching a multilayer structure of PP and EVOH, it is considered to give EVOH sufficient stretchability, that is, to increase the ethylene content in EVOH. ing. However, it is a well-known fact that the barrier property of EVOH is such that the gas barrier property is better as the ethylene content is lower, except for extremely high humidity conditions such as 100% RH. Therefore, when ordinary EVOH is used, EVOH having a high ethylene content is inevitably used even if the gas barrier property is sacrificed in order to provide sufficient stretchability in the stretching step.
[0009]
Furthermore, the above-mentioned prior art documents mainly focus on EVOH among the laminates of EVOH and PP, and the PP to be used is not particularly limited, and only general-purpose PP is described.
[0010]
Thus, the present condition is that the multilayered-structure film which has EVOH and PP which is excellent in an extending | stretching property and has high gas barrier property also under high humidity is not yet obtained.
[0011]
[Problems to be solved by the invention]
An object of the present invention is that a resin layer and a PP layer made of an ethylene-vinyl alcohol copolymer are laminated and stretched through an adhesive resin layer, and maintain the conventional fragrance retaining property. An object of the present invention is to provide a multilayer film which is superior in gas barrier properties, particularly in gas barrier properties under high humidity, incense retention and transparency.
[0012]
[Means for Solving the Problems]
The present inventors have studied a resin used for a PP layer that has hardly been studied, and by combining EVOH having a high gas barrier property with a specific PP resin, a gas barrier even under high humidity conditions. The present invention has been completed by finding a multilayer film having excellent properties and stretchability.
[0013]
That is, the present invention has an ethylene-vinyl alcohol copolymer resin (A) layer having an ethylene content of 20 to 60 mol% and a saponification degree of 90% or more, and a melt flow rate (MFR) at 230 ° C. under a load of 2160 grams is 0. In the range of 1-100 grams / 10 minutes of boiling heptane insoluble components ¹³ Polypropylene resin (C) layer in which the value of stereoregularity index [M5] defined by the following formula (1) is in the range of 0.950 to 0.995 from the absorption intensity of Pmmmm and Pw in the C-NMR spectrum The present invention relates to a multilayer film obtained by stretching a multilayer structure obtained by laminating through an adhesive resin (B) layer at least 3 to 12 times in a uniaxial direction.
[0014]
[M5] = [Pmmmm] / [Pw] (1)
[0015]
Where
[Pmmmm] is an absorption intensity derived from the methyl group of the third unit in a site where 5 units of propylene units are isotactically bonded,
[Pw] is the absorption intensity derived from the methyl group of all propylene units.
[0016]
In a preferred embodiment, the resin (A) constituting the multilayer film is composed of at least two ethylene-vinyl alcohol copolymer resins having different melting points.
[0017]
In a more preferred embodiment, the ethylene content of the resin (A) constituting the multilayer film is 35 to 50 mol%.
[0018]
In a preferred embodiment, the adhesive resin (B) constituting the multilayer film is composed of a carboxylic acid-modified polyolefin.
[0019]
In a preferred embodiment, the multilayer film of the present invention has a multilayer structure in which the resin (A) layer, the polypropylene resin (C) layer, and the adhesive resin (B) layer are co-extruded at the same time in the longitudinal direction. It is a multilayer film that is biaxially stretched 10 to 10 times and 5 to 12 times in the transverse direction.
[0020]
In a preferred embodiment, the multilayer film of the present invention has a multilayer structure comprising an adhesive resin (B) layer and a resin (A) layer on a polypropylene resin (C) layer stretched 4 to 10 times in the longitudinal direction. It is a multilayer film formed by stretching a multilayer structure obtained by extrusion coating the body 5 to 12 times in the transverse direction.
[0021]
In a preferred embodiment, the multilayer film of the present invention is obtained by stretching a polypropylene resin (C) layer having an adhesive resin (B) layer 4 to 10 times in the longitudinal direction, and on the stretched adhesive resin (B) layer. A multilayer film obtained by stretching a multilayer structure obtained by extrusion coating a resin (A) layer or a multilayer structure including the resin (A) layer 5 to 12 times in the transverse direction.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The multilayer film of the present invention has an ethylene-vinyl alcohol copolymer resin (A) layer having an ethylene content of 20 to 60 mol% and a saponification degree of 90% or more, and a melt flow rate (MFR) at 230 ° C. under a load of 2160 grams. In the range of 0.1 to 100 grams / 10 minutes, of boiling heptane insoluble components ¹³ Polypropylene resin (C) layer in which the value of stereoregularity index [M5] defined by the following formula (1) is in the range of 0.950 to 0.995 from the absorption intensity of Pmmmm and Pw in the C-NMR spectrum Is a multilayer film formed by stretching a multilayer structure obtained by laminating via an adhesive resin (B) at least 3 to 12 times in the uniaxial direction.
[0023]
[M5] = [Pmmmm] / [Pw] (1)
[0024]
Where
[Pmmmm] is an absorption intensity derived from the methyl group of the third unit in a site where 5 units of propylene units are isotactically bonded,
[Pw] is the absorption intensity derived from the methyl group of all propylene units.
[0025]
A feature of the present invention is that a polypropylene resin having a specific stereoregularity index [M5] is used. First, the stereoregularity index [M5] will be described.
[0026]
The homopolymer of propylene can be represented by the following formula (A), for example.
[0027]
[Chemical 1]

[0028]
Where propylene unit
[0029]
[Chemical formula 2]

[0030]
Is abbreviated as ┘, where ┘┘ is m and ┘┐ is r, ┘┘┘┘┘ is expressed in mmmm, and the above formula (A) is expressed in mmmmmmr. Note that m represents meso and r represents racemi.
[0031]
The methyl group of the third unit in the polypyrene unit 5 chain (mmmm) represented by this formula (for example, Me of the above formula (A)) ³ , Me ⁴ Derived from ¹³ The absorption intensity in the C-NMR spectrum is Pmmmm, and all the methyl groups (Me ¹ , Me ² , Me ³ If the absorption intensity derived from (...) is Pw, the stereoregularity of the polymer represented by the above formula (A) is the ratio of Pmmmm to Pm, that is, the value of the stereoregularity index obtained from the above formula (1). [M5] can be used for evaluation.
[0032]
The value [M5] of the stereoregularity index of the polypropylene resin (C) used in the present invention is a boiling heptane insoluble component. ¹³ It is determined by C-NMR measurement.
[0033]
The method for extracting boiling heptane-insoluble components is as follows. 3 g of polypropylene resin, 20 g of 2,6-di-tert-butyl-4-methylphenol, and 500 ml of n-decane were placed in a flask equipped with a stirrer and heated and melted at 145 ° C. Then slowly cool to 23 ° C. and then hold on a 23 ° C. water bath for more than 8 hours. The n-decane suspension containing the precipitated polymer (23 ° C., n-decane insoluble component) was filtered and separated with a glass filter (G-4) and dried under reduced pressure, and then the precipitate was used in heptane for at least 6 hours or more. After soxhlet extraction, it was dried to obtain a boiling heptane-insoluble component.
[0034]
Of the obtained boiling heptane insoluble component ¹³ The measuring method of C-NMR is as follows. After 0.35 g of boiling heptane-insoluble component is dissolved in 2.0 ml of hexachlorobutadiene and filtered through a glass filter (G-2), 0.5 ml of deuterated benzene is added and put into an NMR measurement tube having an inner diameter of 10 mm. And using JEOL GX-550 type NMR measuring apparatus at 120 ° C. ¹³ C-NMR measurement is performed. The number of integrations was 1000 times or more. The value of the stereoregularity index [M5] is obtained as an integrated value of peak intensities resulting from the respective structures obtained by the above measurement.
[0035]
The value of the stereoregularity index [M5] of the polypropylene resin (C) is in the range of 0.950 to 0.995, preferably 0.960 to 0.995, and more preferably 0.970 to 0.995. The polypropylene resin (B) having such a range of stereoregularity index [M5] is highly crystalline. When the value of the stereoregularity index [M5] is less than 0.950, drawing at high temperature is impossible and EVOH having a low ethylene content cannot be used.
[0036]
Furthermore, as for polypropylene resin (C), MFR in 230 degreeC and a 2160-gram load is 0.1-100 g / 10min, It is preferable that it is 1-50 g / 10min, 2-10 g / 10min It is more preferable that When the MFR of the polypropylene resin (C) is less than 0.1 gram / 10 minutes, the load applied to the extruder increases, and when it exceeds 100 gram / 10 minutes, flow unevenness occurs between the layers and molding occurs. It becomes difficult.
[0037]
The polypropylene resin (C) having the above properties is a highly stereoregular and highly crystalline polypropylene resin, has high rigidity, and has high heat distortion temperature, melting point, and crystallization temperature, and exhibits excellent heat resistance. Therefore, when a multilayer structure with EVOH is stretched, it can be stretched at a high temperature and can be stretched at a high magnification even by using EVOH having a low ethylene content, which has been impossible to stretch.
[0038]
The polypropylene resin (C) includes conventionally used nucleating agents, antioxidants, antistatic agents, lubricants, antiblocking agents, ultraviolet absorbers, petroleum resins, etc., as long as the object of the present invention is not impaired. May be.
[0039]
Examples of the nucleating agent include sorbitol derivatives such as dibenzylidene sorbitol and dimethyl benzylidene sorbitol, alkali metal salts or aluminum salts of aromatic carboxylic acids such as sodium p-tert-butylbenzoate and aluminum dibenzoate, phosphate 2, Organic crystal nucleating agents represented by metal salts of aromatic phosphates such as sodium 2-methylenebis (4,6-di-tert-butylphenyl), inorganic crystallization nucleating agents such as talc and mica, polycyclohexene A branched cyclic polymer in which a cyclic structure such as polycyclopentene and polycyclobutene is present in the side chain, poly-3-methyl-1-butene, poly-3-methyl-1-pentene, poly-3-ethyl-1-pentene, Branched olefin polymers having 3 or more carbon atoms, such as poly-4-methyl-1-pentene, polyteto Such as polymeric nucleating agent fluoropolymer such as tetrafluoroethylene and the like.
[0040]
Antioxidants include phenolic BHT, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,4 -Dihydroxybenzophenone, 2 (2'-hydroxy-5-methylphenyl) benzotriazole, substituted benzotriazole, 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, ethyl-2-cyano-3,3-diphenyl acrylate , Phenylsalicylate, 4-t-butylphenyl salicylate, and the like.
[0041]
Antistatic agents include alkylamines and their derivatives, higher alcohols, glycerol esters of higher fatty acids, pyridine derivatives, sulfated oils, soaps, sulfates of olefins, alkyl sulfates, fatty acid ethyl sulfonates, alkyls Sulfonate, alkyl naphthalene sulfonate, alkyl benzene sulfonate, naphthalene sulfonate, oxalate sulfonate, phosphate ester, partial fatty acid ester of polyhydric alcohol, ethylene oxide adduct of fatty alcohol, fatty acid Ethylene oxide adduct, fatty amino or fatty acid amide ethylene oxide adduct, alkylphenol ethylene oxide adduct, alkyl naphthol ethylene oxide adduct, polyhydric alcohol partial Ethylene oxide adducts of fatty acid esters, polyethylene glycol, and the like.
[0042]
Examples of the lubricant include stearic acid, stearic acid amide, oleic acid amide, higher alcohol, liquid paraffin and the like.
[0043]
Examples of the anti-blocking agent include synthetic silica, calcium carbide, amorphous aluminosilicate, zeolite, diatomaceous earth, talc, feldspar, and crosslinked polymethyl methacrylate.
[0044]
Examples of the ultraviolet absorber include ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-). Butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4octoxybenzophenone and the like.
[0045]
Examples of petroleum resins include hydrogenated petroleum resins such as polydicyclopentadiene having a Tg (glass transition temperature) of 70 ° C. or more and a hydrogenation rate of 99% or more, or terpene resins substantially free of polar groups, such as pinene, dipentene, and carene. , Myrcene, osymene, limonene, terpyrene, zabinene, tricyclene, bisabolene, gingipyrene, santalen, camphorene, mylene, totarene and the like.
[0046]
The polypropylene resin (C) may contain polypropylene or polyolefin other than the polypropylene resin (C) used in the present invention as long as the object of the present invention is not impaired. Further, the polypropylene resin (C) may be used in a mixed system of two or more types.
[0047]
The EVOH resin (A) used in the present invention has an ethylene content of about 20 to 60 mol% and a saponification degree of about 90% or more.
[0048]
The ethylene content of the resin (A) is about 20 to 60 mol%, preferably about 35 to 50 mol%. When the ethylene content is less than about 20 mol%, the laminate with PP cannot be stretched. On the other hand, when ethylene content exceeds about 60 mol%, the barrier property of the obtained multilayer stretched film is not sufficient. The ethylene content of the resin (A) is more preferably about 37 to 48 mol%, and most preferably about 40 to 45 mol%.
[0049]
The saponification degree of the resin (A) needs to be about 90 mol% or more, more preferably about 95 mol% or more, and most preferably about 99 mol% or more. It is preferable that the saponification degree is in such a range from the viewpoint of maintaining the barrier property of the resulting multilayer film.
[0050]
The ethylene content and saponification degree of the resin (A) are as follows: ¹ It is a value quantified by 1 H-NMR.
[0051]
Furthermore, the resin (A) is more preferably a blend of at least two types of EVOH having different melting points.
[0052]
When two types of EVOH are used, the content is preferably about 10 to 90% by weight, more preferably about 20 to 80% by weight, and most preferably about 30 to 70% by weight. .
[0053]
When at least two types of EVOH are blended, it can be distinguished from EVOH having a single composition in thermal analysis, particularly DSC analysis. When the melting points of two or more types of EVOH to be blended are greatly different, two or more DSC peaks are observed. When EVOH having a close melting point is blended, it may appear as a single peak, but when the melting point is more than a certain value, the peak shape becomes broad. However, even in the case of a single peak, it may be possible to observe the presence of two or more peaks or shoulder peaks with respect to the main peak by lowering the DSC temperature increase rate.
[0054]
The melting point of EVOH is adjusted, for example, by changing the ethylene content. When the ethylene content is the same, the melting point is adjusted by changing the degree of saponification.
[0055]
The overall ethylene content in the blended EVOH is as described above, but the difference in ethylene content of the EVOH blended is preferably about 3-30 mol%, more preferably about 3-15. Mol%.
[0056]
The saponification degree of the blended EVOH is as described above, but the saponification degree of the EVOH to be blended is preferably about 90 mol% or more, more preferably about 95 mol% or more, and about 99 mol % Or more is most preferable.
[0057]
Furthermore, in the present invention, as long as the stretchability and barrier properties of the film of the present invention are not impaired, EVOH as a third component can be further added in addition to the EVOH resin.
[0058]
Moreover, as long as the performance of the resin (A) used in the present invention is not impaired, EVOH may be a copolymer with a small amount of olefin. Examples of monomers that can be copolymerized include α-olefins such as propylene, 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, and 1-octene.
[0059]
Moreover, suitable MFR (210 degreeC, 2160-g load, based on JISK7210) of resin (A) used for this invention is 0.1-100 g / 10min, More preferably, 0.5-50 g / 10 minutes.
[0060]
When the MFR is less than 0.1 gram / 10 minutes, melt molding becomes difficult, and there is a possibility that only a film can be formed by a solution coating method, and there is a possibility that a high-magnification stretched film in the present invention cannot be obtained. On the other hand, if the MFR exceeds 100 g / 10 min, not only may the stretching at a high magnification be difficult after the multilayer structure is obtained, but sufficient strength of the obtained multilayer stretched film is obtained. There is also a risk of not being able to.
[0061]
In addition, a heat stabilizer, an ultraviolet absorber, an antioxidant, a colorant, a filler, other resins (polyamide, polyolefin, etc.), and a plasticizer such as glycerin or glycerin monostearate are used as long as the object of the present invention is not impaired. It can also be blended with (A).
[0062]
Examples of the adhesive resin (B) include CAX-3036 manufactured by DuPont, Admer manufactured by Mitsui Chemicals, Adtex manufactured by Nippon Polyolefin Co., and a plexer manufactured by USI.
[0063]
Among these, it is preferable in the present invention to use a so-called acid-modified polyolefin resin based on a polyolefin resin and graft-polymerized with an unsaturated carboxylic acid or its anhydride, ester, amide or the like. Among these, it is more preferable to use a polypropylene resin as a base. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.
[0064]
The MFR of the adhesive resin (B) at 230 ° C. and a load of 2160 grams is preferably about 1 to 50 grams / 10 minutes, and more preferably about 2 to 10 grams / 10 minutes. If the adhesive resin (b) is less than about 1 gram / 10 minutes, the load on the extruder may increase, and if it exceeds about 50 gram / 10 minutes, flow unevenness occurs between the layers, making molding difficult. There is a risk of becoming.
[0065]
The multilayer film of the present invention is obtained by stretching a multilayer structure in which an EVOH (A) layer and a highly crystalline PP resin (C) layer are laminated via an adhesive resin (B) layer. The crystalline PP layer is at least uniaxially, preferably biaxially oriented.
[0066]
As a specific layer structure of the multilayer structure, PP resin (C) is represented as C, adhesive resin (B) as B, and EVOH resin (A) as A. C / B / A / B / C A five-layer structure, a four-layer structure of C / B / A / B, a three-layer structure of C / B / A, etc. are not particularly limited. In addition to these layers, a layer imparting functionalities such as heat sealability, antistatic properties, and moisture resistance can also be provided.
[0067]
In order to impart heat sealability, another heat seal layer can be provided on the outermost PP on one or both sides. That is, when the heat-sealable resin layer is represented by H, H / C / B / A / B / C, H / C / B / A / B / C / H, H / C / B / A / B, H Examples of the layer structure include / C / B / A / B / H and H / C / B / A. The heat sealable resin may be a random copolymer of propylene and an α-olefin having 4 or more carbon atoms, or a random copolymer of propylene, an α-olefin having 4 or more carbon atoms and ethylene, polyethylene, ethylene vinyl acetate. (EVA) and the like.
[0068]
In order to impart antistatic properties, the antistatic agents listed above are added to at least one PP layer in one or more mixed systems, and the added PP layer is subjected to a surface treatment such as corona treatment. . There is also a method in which at least one outermost layer is coated with a solution to which an antistatic agent is added.
[0069]
In order to impart moisture resistance, one or more of the above-described petroleum resins or terpene resins substantially free of polar groups are added to at least one PP layer.
[0070]
In addition, a recovery (Reg) layer can be provided in the above layer configuration as necessary. Such a recovery layer may be provided separately, or a recovered material may be substantially added to the PP layer or the adhesive resin layer in the present invention to form a recovery layer. Specific examples of the layer structure include Reg / C / B / A / B / C, Reg / C / B / A / B / C / Reg, C / Reg / B / A / B / C, C / Reg / B / A / B / Reg / C, Reg / C / B / A / B, C / Reg / B / A / B, Reg / C / B / A, C / Reg / B / A, etc. However, it is not limited to this.
[0071]
In addition, a corona discharge treatment or a flame treatment can be performed on the film surface for printing and laminating.
[0072]
The thickness of the stretched multilayer stretched film is preferably about 10 μm or more in terms of the total thickness. About 15 to 100 μm is more preferable, and about 15 to 50 μm is more preferable.
[0073]
The layer thickness of the adhesive resin (B) is preferably about 0.5 to 50 μm, more preferably about 2 to 20 μm, and further preferably 3 to 10 μm. If the adhesive resin (B) is less than 0.5 μm, the interlayer adhesiveness between the PP (C) layer and the EVOH (A) layer will be insufficient, and the desired multilayer film may not be obtained. If it exceeds 50 μm, the cost increases.
[0074]
Moreover, about 1-20 micrometers is preferable and, as for EVOH (A) layer, about 4-9 micrometers is more preferable. When the EVOH (A) layer is less than about 1 μm, it is difficult to obtain the target barrier properties, and when it is 20 μm or more, the obtained stretched film may have poor rigidity.
[0075]
Further, the layer thickness of the PP (C) layer is preferably about 5 to 95 μm, more preferably about 8 to 50 μm, and further preferably about 10 to 30 μm.
[0076]
When the Reg layer is provided, the thickness of the Reg layer is not particularly limited.
[0077]
The production method of the multilayer structure before stretching is as follows: PP resin (C), adhesive resin (B), EVOH resin (A) are extruded from separate extruders in a die, for example, C / B / A / B / It is laminated and coextruded so as to be C, and cast on a cooling roll of 50 ° C. or lower, preferably 40 ° C. or lower to produce a multilayer structure.
[0078]
Examples of a method for stretching a multilayer laminated structure of PP and EVOH include a sequential biaxial stretching method or a simultaneous biaxial stretching method, which is a general manufacturing method.
[0079]
When stretching by the sequential biaxial stretching method, for example, PP resin (C), adhesive resin (B) and EVOH resin (A) are extruded from separate extruders in a die, and C / B / A / B / C It laminates so that it may become, co-extrusion, it casts on a cooling roll, and produces a lamination sheet. Next, the film is stretched in the machine direction, and then stretched in the transverse direction by a tenter to produce a desired multilayer film.
[0080]
Moreover, PP resin (C) and adhesive resin (B) are laminated | stacked and coextruded so that it may become PP / adhesive resin in an extrusion die from a separate extruder, and it casts on a cooling roll, and produces a laminated sheet. Next, after stretching in the machine direction, an EVOH (A) layer or a multilayer structure containing the EVOH (A) layer is extruded from another extruder and extruded on the adhesive layer, and then stretched in the transverse direction by a tenter. The desired multilayer film can also be produced.
[0081]
Furthermore, PP resin (C) is extruded by an extruder and cast on a cooling roll to form a sheet. Next, after stretching in the machine direction, a multilayer structure including the adhesive resin (B) layer and the EVOH (A) layer is extruded from another extruder so that the (B) layer comes on the PP (C) layer. After extrusion lamination, the desired multilayer film can be produced by stretching in the transverse direction with a tenter.
[0082]
As the simultaneous biaxial stretching method, for example, PP resin (C), adhesive resin (B), and EVOH resin (A) are extruded from separate extruders to be C / B / A / B / C in a die. Laminate and co-extrusion from a cylindrical die to create a tubular laminate. Subsequently, the target multilayer film is produced by simultaneously stretching in the machine direction and the transverse direction.
[0083]
Also, for example, PP resin (C), adhesive resin (B) and EVOH resin (A) are laminated from different extruders in an extrusion die so as to be C / B / A / B / C, and co-extruded, Cast on a cooling roll to create a multilayer structure. Then, the desired multilayer film can be produced by stretching simultaneously in the machine direction and the transverse direction with a tenter.
[0084]
The layer configuration shown here is an example and is not particularly limited.
[0085]
Hereafter, the preferable manufacturing method which obtains the multilayer film of this invention is demonstrated.
[0086]
As a first method, sequential biaxial stretching of a co-extruded product will be described. PP resin (C), adhesive resin (B) and EVOH resin (A) are laminated from different extruders in an extrusion die, for example, C / B / A / B / C, co-extruded, A multilayer structure is produced by casting on a cooling roll of 50 ° C. or lower, preferably about 40 ° C. or lower. Next, after stretching at about 100 to 140 ° C., preferably about 110 to 130 ° C., about 4 to 7 times, preferably about 5 to 6 times in the machine direction, the preheating temperature is about 180 to 200 ° C., preferably about 185 Heating at ˜195 ° C. and stretching at about 160 to 175 ° C., preferably about 165 to 170 ° C. in the transverse direction about 7 to 12 times, preferably about 8 to 10 times to produce the desired multilayer film it can.
[0087]
As a second method, a sequential biaxial stretching method using extrusion coating will be described. PP resin (C) and adhesive resin (B) are extruded from separate extruders, for example, laminated to C / B and coextruded, and cooled to about 50 ° C. or less, preferably about 40 ° C. or less. Cast on a roll to create a multilayer structure. Next, after stretching at about 100 to 140 ° C., preferably about 110 to 130 ° C., about 4 to 7 times, preferably about 5 to 6 times in the machine direction, EVOH is extruded from another extruder, for example, on the adhesive layer. After extrusion lamination, it is heated at a preheating temperature of about 180 to 200 ° C., preferably about 185 to 195 ° C. and about 160 to 175 ° C., preferably about 165 to 170 ° C., about 7 to 12 times in the transverse direction, preferably Can be stretched about 8-10 times to produce the desired multilayer film.
[0088]
As a third method, a simultaneous biaxial stretching method will be described. That is, PP resin (C), adhesive resin (B), and EVOH resin (A) are laminated from different extruders in an extrusion die, for example, C / B / A / B / C. Further, it is coextruded and cooled with cooling water of about 50 ° C. or lower, preferably about 40 ° C. or lower to prepare a tube-shaped laminate. Next, after heating with an annular infrared heater, it is bubbled with pressurized air and is about 4-7 times in the machine direction, preferably about 5-6 times, and about 4-7 times in the lateral direction, preferably about 5-6. The desired multilayer film can be produced by stretching simultaneously and twice.
[0089]
As a fourth method, simultaneous biaxial stretching using a tenter method will be described. That is, PP resin (C), adhesive resin (B), and EVOH resin (A) are laminated from different extruders in an extrusion die, for example, C / B / A / B / C, and co-extruded. And cast on a cooling roll of about 50 ° C. or less, preferably about 40 ° C. or less to produce a multilayer structure. Then, in the tenter, the preheating temperature is about 180 to 200 ° C, preferably about 185 to 195 ° C, and about 160 to 175 ° C, preferably about 165 to 170 ° C, about 4 to 12 times in the machine direction, preferably about The desired multilayer film can be produced by simultaneously stretching 5 to 10 times and about 4 to 12 times, preferably about 5 to 10 times in the transverse direction.
[0090]
The multilayer film thus obtained has excellent mechanical strength and gas barrier properties, and has cost merit. Therefore, it can be widely used in the packaging field where gas barrier properties are required. In particular, since the multilayer film of the present invention does not generate harmful gases when burned, it can be used for a wide range of uses such as food packaging and pharmaceuticals.
[0091]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited at all by this.
[0092]
The stereoregularity index [M5] of the PP resin (C) in each example is obtained by extracting boiling heptane-insoluble components according to the above method, ¹³ It was determined by measuring C-NMR.
[0093]
Evaluation of a multilayer structure and a multilayer film followed the following method.
[0094]
(1) Stretchability (in the case of simultaneous coextrusion molding)
The cutting state at the time of stretching and the state of the produced multilayer film were visually evaluated and represented in three stages.
○: Stretchable.
Δ: Partial stretching unevenness was observed, but stretching was possible.
X: Unstretchable (cut).
[0095]
(2) Stretchability (for extrusion coating)
The cutting state at the time of stretching and the state of the produced multilayer film were visually evaluated and represented in three stages.
○: Stretchable.
Δ: Partial stretching unevenness was observed, but stretching was possible.
X: Unstretchable.
[0096]
(3) Appearance of film
The state of the prepared multilayer film was visually evaluated and the haze of the film was measured and evaluated.
[0097]
Visual evaluation It was expressed in the following three stages.
○: Transparent.
Δ: Ground glass (matte).
X: Reticulated.
[0098]
The haze value was measured using a haze meter 300A manufactured by Nippon Denshoku Industries Co., Ltd. according to the method described in JIS K7150. The value is measured by overlaying four films.
[0099]
(4) Oxygen permeability
MODERN CONTROLS INC. Measurement was performed in accordance with the method described in JIS K7126 (isobaric method) under high humidity conditions of 20 ° C., 85% RH, and 95% RH using an oxygen permeation measuring apparatus MOCONOX-TRAN 2/20 type. The evaluated samples were 5 × 10 times in the case of a stretched film having a C / B / A / B / C configuration, and 11 times in the case of a stretched film having a C / B / A configuration. The oxygen permeability referred to in the present invention is the oxygen transmission rate (ml / m) measured with an arbitrary EVOH film thickness for a stretched film having a C / B / A / B / C configuration or a C / B / A configuration. ² · Day · atm) converted to oxygen permeation amount when the thickness of the EVOH layer is 20 µm (ml · 20 µm / m) ² (Day / atm).
[0100]
Example 1
EVOH (A) having an ethylene content of 47 mol%, a saponification degree of 99.6%, MFR = 13 grams / 10 minutes (210 ° C., 2160 g load), stereoregularity index [M5] = 0.98, Highly crystalline polypropylene (C) with MFR = 2 g / 10 min (210 ° C., 2160 g load), maleic anhydride-modified polypropylene resin (B) with MFR = 6.0 g / 10 min (210 ° C., 2160 g load) Lamination was carried out in an extrusion die from separate extruders so as to have a C / B / A / B / C configuration, co-extruded, and cast on a 35 ° C. cooling roll to prepare a laminated sheet. Next, the film was stretched 5 to 6 times in the machine direction at 120 ° C., heated at a preheating temperature of 185 ° C., and stretched 8 to 10 times in the transverse direction at 165 ° C. to produce the desired multilayer film, and then evaluated as described above. The evaluation described in the item was performed. The obtained results are shown in Table 1.
[0101]
Example 2
EVOH (A) having an ethylene content of 44 mol%, a saponification degree of 99.5%, MFR = 13 g / 10 min (210 ° C., 2160 g load), stereoregularity index [M5] = 0.98, MFR = Highly crystalline polypropylene (C) with 2 grams / 10 minutes (210 ° C, 2160 grams load), Maleic anhydride modified polypropylene resin (B) with MFR = 6 grams / 10 minutes (210 ° C, 2160 grams load) Were laminated and coextruded in an extrusion die from different extruders to form a C / B / A / B / C structure, and cast on a 35 ° C. cooling roll to prepare a laminated sheet. Next, after stretching 5 to 6 times in the machine direction at 120 ° C., the preheating temperature is heated at 190 ° C., and the target multilayer film is produced by stretching 8 to 10 times in the transverse direction at 170 ° C. The evaluation described in the evaluation items was performed. The obtained results are shown in Table 1.
[0102]
Example 3
The following two EVOH resins a1 and a2:
EVOH resin a1; ethylene content 38 mol%, saponification degree 99.6%, MFR 3.8 g / 10 min (210 ° C., 2160 g), melting point 175 ° C., phosphorus compound (potassium dihydrogen phosphate) as elemental phosphorus Containing 100 ppm in terms of sodium salt (sodium acetate) 50 ppm in terms of sodium element;
EVOH resin a2; ethylene content 48 mol%, saponification degree 99.6%, MFR 33 g / 10 min (210 ° C., 2160 g), melting point 160 ° C., phosphorus compound (potassium dihydrogen phosphate) in terms of phosphorus element Contains 50 ppm;
After dry blending 50 parts by weight, each was melt-extruded with a screw having a Maddock-type kneading part having a diameter of 40 mm, L / D = 24, and a compression ratio of 3.8 to obtain pellets of a resin composition. The obtained EVOH (A) had an ethylene content of 43 mol%, a saponification degree of 99.6%, and MFR = 7.7 grams / 10 minutes (210 ° C., 2160 grams load).
[0103]
EVOH (A), stereoregularity index [M5] = 0.98, high crystalline polypropylene (C) with MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load), MFR = 6 grams / 10 35 minutes (210 ° C., 2160 gram load) of maleic anhydride-modified polypropylene resin (B) is laminated and coextruded in an extrusion die from a separate extruder so as to have a composition of C / B / A / B / C. A laminated sheet was prepared by casting on a cooling roll at 0 ° C. Next, the film was stretched 5 to 6 times in the machine direction at 120 ° C., heated at a preheating temperature of 195 ° C., and stretched 8 to 10 times in the transverse direction at 170 ° C. The evaluation described in the evaluation items was performed. The obtained results are shown in Table 1.
[0104]
Example 4
Highly crystalline polypropylene (C) with stereoregularity index [M5] = 0.98, MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load), MFR = 6 grams / 10 minutes (210 ° C., 2160 grams) Load) maleic anhydride-modified polypropylene resin (B) from different extruders, laminated in a die so that it becomes a highly crystalline polypropylene / adhesive resin, co-extruded, cast on a cooling roll of 35 ° C or lower and laminated Created a sheet. Next, after stretching 5 to 6 times in the machine direction at 115 ° C., the ethylene content was 47 mol%, saponification degree 99.6%, MFR = 33 g / 10 min (210 ° C., 2160 g) from another extruder. After extruding EVOH (A) which is a load) and extrusion lamination onto the adhesive layer, the preheating temperature is heated at 185 ° C. and stretched 8 to 10 times in the transverse direction at 165 ° C. to produce the desired multilayer film The evaluation described in the above evaluation items was performed. The obtained results are shown in Table 2.
[0105]
Example 5
Highly crystalline polypropylene (C) with stereoregularity index [M5] = 0.98, MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load), MFR = 6 grams / 10 minutes (210 ° C., 2160 grams) Load) maleic anhydride modified polypropylene resin (B) from different extruders, laminated in a die to become highly crystalline polypropylene / adhesive resin, coextruded, cast on 35 ° C cooling roll and laminated sheet It was created. Next, after stretching 5 to 6 times in the machine direction at 115 ° C., ethylene content was 44 mol%, saponification degree 99.5%, MFR = 13 grams / 10 minutes (210 ° C., 2160 grams load) from another extruder. EVOH (A) is extruded and laminated on the adhesive layer, heated at a preheating temperature of 190 ° C., and stretched 8 to 10 times in the transverse direction at 170 ° C. to produce the desired multilayer film. The evaluation described in the evaluation item was performed. The obtained results are shown in Table 2.
[0106]
Example 6
Highly crystalline polypropylene (C) with stereoregularity index [M5] = 0.98, MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load), MFR = 6 grams / 10 minutes (210 ° C., 2160 grams) Load) maleic anhydride modified polypropylene resin (B) from different extruders, laminated in a die to become highly crystalline polypropylene / adhesive resin, coextruded, cast on 35 ° C cooling roll and laminated sheet It was created. Next, after stretching 5 to 6 times in the machine direction at 115 ° C., EVOH (A) obtained by blending two types of EVOH prepared in Example 3 was extruded from another extruder onto the adhesive layer. After extrusion lamination, the preheating temperature was heated at 195 ° C., and the target multilayer film was produced by stretching 8 to 10 times in the transverse direction at 170 ° C., and then the evaluation described in the above evaluation items was performed. The obtained results are shown in Table 2.
[0107]
Example 7
EVOH (A) having an ethylene content of 47 mol%, a saponification degree of 99.6%, MFR = 13 g / 10 min (210 ° C., 2160 g load), stereoregularity index [M5] = 0.98, High crystalline polypropylene (C) with MFR = 2 gram / 10 minutes (210 ° C., 2160 gram load), maleic anhydride modified polypropylene resin with MFR = 6.0 gram / 10 minutes (210 ° C., 2160 gram load) (B) is laminated in an extrusion die from a separate extruder so as to have a structure of C / B / A / B / C, coextruded from a cylindrical die, cooled with cooling water at 30 ° C., and laminated in a tube shape Created the body. Next, after heating the set temperature of the annular infrared heater at 380 ° C., it is simultaneously stretched 5.0 to 6.0 times in the machine direction and 5.0 to 6.0 times in the transverse direction in the form of bubbles fed with pressurized air. After the target multilayer film was manufactured, the evaluation described in the above evaluation items was performed. The obtained results are shown in Table 1.
[0108]
Example 8
EVOH (A) having an ethylene content of 44 mol%, a saponification degree of 99.5%, MFR = 13 g / 10 min (210 ° C., 2160 g load), stereoregularity index [M5] = 0.98, MFR = Highly crystalline polypropylene (C) with 2 grams / 10 minutes (210 ° C, 2160 grams load), Maleic anhydride modified polypropylene resin (B) with MFR = 6 grams / 10 minutes (210 ° C, 2160 grams load) Were laminated in an extrusion die from separate extruders and coextruded from a cylindrical die, and cooled with 30 ° C. cooling water to form a tubular laminate. Next, after heating the set temperature of the annular infrared heater at 390 ° C., it is stretched 5.0 to 6.0 times in the machine direction and 5.0 to 6.0 times in the lateral direction in the form of bubbles fed with pressurized air. After the target multilayer film was manufactured, the evaluation described in the above evaluation items was performed. The obtained results are shown in Table 1.
[0109]
Example 9
EVOH (A) obtained by blending two types of EVOH prepared in Example 3, stereoregularity index [M5] = 0.98, MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) ) High crystalline polypropylene (C), and MFR = 6 grams / 10 minutes (210 ° C., 2160 grams load) maleic anhydride-modified polypropylene resin (B) is extruded from a separate extruder in a C / B in an extrusion die. Laminated to have a structure of / A / B / C, coextruded from a cylindrical die, and cooled with cooling water at 30 ° C. to form a tubular laminate. Next, after heating the set temperature of the annular infrared heater at 400 ° C., it is stretched at the same time in the form of bubbles in which pressurized air is fed 5.0 to 6.0 times and 5.0 to 6.0 times in the lateral direction. After the target multilayer film was manufactured, the evaluation described in the above evaluation items was performed. The obtained results are shown in Table 1.
[0110]
Example 10
EVOH (A) having an ethylene content of 47 mol%, a saponification degree of 99.6%, MFR = 13 grams / 10 minutes (210 ° C., 2160 g load), stereoregularity index [M5] = 0.98, High crystalline polypropylene (C) with MFR = 2 gram / 10 minutes (210 ° C., 2160 gram load), maleic anhydride modified polypropylene resin with MFR = 6.0 gram / 10 minutes (210 ° C., 2160 gram load) (B) was laminated and coextruded in an extrusion die from a separate extruder so as to have a structure of C / B / A / B / C, and cast on a 35 ° C. cooling roll to prepare a laminated sheet. Next, in the tenter, the preheating temperature is heated at 185 ° C., and at 165 ° C., the target multilayer film is produced by simultaneously stretching 5 to 6 times in the machine direction and 9 to 10 times in the transverse direction. The evaluation described in the item was performed. The obtained results are shown in Table 1.
[0111]
Example 11
EVOH (A) having an ethylene content of 44 mol%, a saponification degree of 99.5%, MFR = 13 g / 10 min (210 ° C., 2160 g load), stereoregularity index [M5] = 0.98, MFR = Highly crystalline polypropylene (C) with 2 grams / 10 minutes (210 ° C, 2160 grams load), Maleic anhydride modified polypropylene resin (B) with MFR = 6 grams / 10 minutes (210 ° C, 2160 grams load) Were laminated and coextruded to form a C / B / A / B / C in an extrusion die from a separate extruder, and cast on a 35 ° C. cooling roll to prepare a laminated sheet. Next, in the tenter, the preheating temperature was heated at 190 ° C., and the target multilayer film was simultaneously stretched at 170 ° C. by 5 to 6 times in the machine direction and 9 to 10 times in the transverse direction. The evaluation described in the item was performed. The obtained results are shown in Table 1.
[0112]
Example 12
EVOH (A) obtained by blending two types of EVOH prepared in Example 3, stereoregularity index [M5] = 0.98, MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) ) High crystalline polypropylene (C), and MFR = 6 grams / 10 minutes (210 ° C., 2160 grams load) maleic anhydride-modified polypropylene resin (B) is extruded from a separate extruder in a C / B in an extrusion die. Laminated and coextruded so as to have a structure of / A / B / C, and cast on a 35 ° C. cooling roll to prepare a laminated sheet. Next, in the tenter, the preheating temperature was heated at 195 ° C., and the target multilayer film was produced at 170 ° C. by simultaneously stretching 5 to 6 times in the machine direction and 9 to 10 times in the transverse direction. The evaluation described in the item was performed. The obtained results are shown in Table 1.
[0113]
Comparative Example 1
In Example 1, instead of highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) is used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0114]
Comparative Example 2
In Example 2, instead of the highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0115]
Comparative Example 3
In Example 3, instead of the highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) is used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0116]
Comparative Example 4
In Example 4, polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 gram / 10 minutes (210 ° C., 2160 gram load) was used instead of the highly crystalline polypropylene (C). Evaluation was performed in the same manner as in Example 4 except that. The results are shown in Table 2.
[0117]
Comparative Example 5
In Example 5, instead of the highly crystalline polypropylene (C), a highly crystalline polypropylene (C5) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) The evaluation was performed in the same manner as in Example 4 except that. The results are shown in Table 2.
[0118]
Comparative Example 6
In Example 6, instead of the highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 4 except that. The results are shown in Table 2.
[0119]
Comparative Example 7
In Example 7, instead of highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0120]
Comparative Example 8
In Example 8, instead of highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0121]
Comparative Example 9
In Example 9, instead of the highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0122]
Comparative Example 10
In Example 10, instead of highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0123]
Comparative Example 11
In Example 11, instead of the highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0124]
Comparative Example 12
In Example 12, instead of the highly crystalline polypropylene (C), polypropylene (C) having a stereoregularity index [M5] = 0.92 and MFR = 2 grams / 10 minutes (210 ° C., 2160 grams load) was used. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.
[0125]
[Table 1]

[0126]
[Table 2]

[0127]
The film of the example obtained by using the polypropylene having the stereoregularity index [M5] in a specific range was excellent in stretchability and kept high in gas barrier properties under high humidity. Also, the appearance and transparency were excellent. On the other hand, the film of the comparative example obtained using the polypropylene having the stereoregularity index [M5] outside the specific range had poor stretchability and poor molding. Also, the appearance and transparency were poor.
[0128]
【The invention's effect】
A multilayer film obtained by using polypropylene having a stereoregularity index [M5] and MFR in a specific range and EVOH having an ethylene content and a saponification degree in a specific range is excellent in stretchability and gas at high humidity. The barrier property is also kept high, and the appearance and transparency are excellent.

Claims (7)

An ethylene-vinyl alcohol copolymer resin (A) layer having an ethylene content of 20 to 60 mol% and a saponification degree of 90% or more, and a melt flow rate (MFR) at 230 ° C and a load of 2160 grams is 0.1 to 100 grams / The value of stereoregularity index [M5] defined by the following formula (1) is 0.950 to the range of 10 minutes from the absorption intensity of Pmmmm and Pw in the ¹³ C-NMR spectrum of the boiling heptane-insoluble component. A multilayer film obtained by stretching a multilayer structure in which a polypropylene resin (C) layer in a range of 0.995 is laminated via an adhesive resin (B) layer at least 3 to 12 times in a uniaxial direction.
[M5] = [Pmmmm] / [Pw] (1)
Where
[Pmmmm] is an absorption intensity derived from the methyl group of the third unit in a site where 5 units of propylene units are isotactically bonded,
[Pw] is the absorption intensity derived from the methyl group of all propylene units. The multilayer film according to claim 1, wherein the resin (A) comprises at least two kinds of ethylene-vinyl alcohol copolymer resins having different melting points. The multilayer film according to claim 1 or 2, wherein the resin (A) has an ethylene content of 35 to 50 mol%. The multilayer film according to any one of claims 1 to 3, wherein the adhesive resin (B) comprises a carboxylic acid-modified polyolefin. A multilayer structure in which the resin (A) layer, the polypropylene resin (C) layer, and the adhesive resin (B) layer are co-extruded at the same time is doubled 4 to 10 times in the vertical direction and 5 to 12 times in the horizontal direction. The multilayer film according to any one of claims 1 to 4, wherein the multilayer film is axially stretched. A multilayer structure formed by extrusion coating a multilayer structure including an adhesive resin (B) layer and a resin (A) layer on a polypropylene resin (C) layer stretched 4 to 10 times in the longitudinal direction, The multilayer film according to any one of claims 1 to 5, which is stretched 5 to 12 times in the transverse direction. A polypropylene resin (C) layer having an adhesive resin (B) layer is stretched 4 to 10 times in the longitudinal direction, and a resin (A) layer or a resin (A) layer is formed on the stretched adhesive resin (B) layer. The multilayer film according to any one of claims 1 to 5, wherein a multilayer structure formed by extrusion coating of a multilayer structure containing bismuth is stretched 5 to 12 times in the transverse direction.