JP2004269725A - Resin composition and multilayer vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resin composition which maintains characteristics such as gas barrier properties exhibited by an ethylene-vinyl alcohol copolymer and is excellent in adhesiveness with polyester resins. <P>SOLUTION: The resin composition comprises the ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) with a polar group, wherein the weight ratio (A/B) is 50/50-99.8/0.2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００４６】
また、ボロン酸エステル基、ボロン酸無水物基およびボロン酸塩基は、それぞれ下記式（ＩＩ）、（ＩＩＩ）および（ＩＶ）で示される。
【００４７】
【化２】

【００４８】
【化３】

【００４９】
【化４】

【００５０】
｛式中、Ｘ_１およびＸ_２は同一または異なり、それぞれ水素原子、脂肪族炭化水素基（炭素数１〜２０の直鎖状、または分岐状アルキル基、またはアルケニル基等）、脂環式炭化水素基（シクロアルキル基、シクロアルケニル基等）、および、芳香族炭化水素基（フェニル基、ビフェニル基等）を表わし、ここで脂肪族炭化水素基、脂環式炭化水素基および芳香族炭化水素基は置換基を有していてもよく、また、Ｘ_１とＸ_２は結合していてもよく、ただし、Ｘ_１およびＸ_２がともに水素原子であることはない。またＲ_１、Ｒ_２およびＲ_３は上記Ｘ_１およびＸ_２と同様の水素原子、脂肪族炭化水素基、脂環式炭化水素基および芳香族炭化水素基を表わし、Ｍはアルカリ金属を表わす。上記式において、脂肪族炭化水素基、脂環式炭化水素基および芳香族炭化水素基が有することができる置換基の例としては、例えばカルボキシル基、ハロゲン原子等を挙げることができる。｝
【００５１】
上記ホウ素含有極性基を有する炭化水素系重合体は、ＥＶＯＨとの相容性が非常に優れているので、このような重合体を含む樹脂組成物でなる層とＰＥＳ層とからなる多層容器の透明性は、ＥＶＯＨ層とＰＥＳ層とからなる多層容器の透明性と比較しても何ら遜色はない。さらに、前者は耐衝撃剥離性においては後者よりもはるかに優れていることが見出された。
【００５２】
一般式（ＩＩ）で示されるボロン酸エステル基の具体例としては、次の基が挙げられる：ボロン酸ジメチルエステル基、ボロン酸ジエチルエステル基、ボロン酸ジプロピルエステル基、ボロン酸ジイソプロピルエステル基、ボロン酸ジブチルエステル基、ボロン酸ジヘキシルエステル基、ボロン酸ジシクロヘキシルエステル基、ボロン酸エチレングリコールエステル基、ボロン酸プロピレングリコールエステル基、ボロン酸１，３−プロパンジオールエステル基、ボロン酸１，３−ブタンジオールエステル基、ボロン酸ネオペンチルグリコールエステル基、ボロン酸カテコールエステル基、ボロン酸グリセリンエステル基、ボロン酸トリメチロールエタンエステル基等。
【００５３】
上記一般式（ＩＶ）で示されるボロン酸塩基としては、ボロン酸のアルカリ金属塩基等が挙げられる。具体的には、ボロン酸ナトリウム塩基、ボロン酸カリウム塩基等が挙げられる。
【００５４】
上記ホウ素含有極性基を有する熱可塑性樹脂（Ｂ）中の上記ホウ素含有極性基の含有量は特に制限はないが、０．０００１〜１ｍｅｑ／ｇ（ミリ当量／ｇ）が好ましく、０．００１〜０．１ｍｅｑ／ｇがより好ましい。
【００５５】
上記ホウ素含有極性基を有する炭化水素系重合体の製法は特に限定されず、上記１）〜４）の方法のいずれも適用することができる。それらのうち、１）、２）、および４）の方法の代表例について次に記載する。
【００５６】
上記１）の方法（炭化水素系重合体の形成に用いられる単量体と、極性基、または、該極性基を形成し得る基を含有する単量体とを共重合する方法）により、ホウ素含有極性基を有する単量体と、オレフィン系重合体、ビニル系重合体、ジエン系重合体等を形成し得る単量体とを共重合させることにより、ホウ素含有極性基を有する炭化水素系重合体が得られる。上記ホウ素含有極性基を有する単量体としては、例えば、３−アクリロイルアミノベンゼンボロン酸、３−アクリロイルアミノベンゼンボロン酸エチレングリコールエステル、３−メタクリロイルアミノベンゼンボロン酸、３−メタクリロイルアミノベンゼンボロン酸エチレングリコールエステル、４−ビニルフェニルボロン酸、４−ビニルフェニルボロン酸エチレングリコールエステル等が挙げられる。
【００５７】
ホウ素含有極性基を有する炭化水素系重合体はまた、上記２）の方法により、ホウ素含有極性基を有するチオールを連鎖移動剤として、オレフィン系重合体、ビニル系重合体、ジエン系重合体等を形成し得る単量体をラジカル重合することにより得られる。得られた重合体は、末端にホウ素含有極性基を有する。
【００５８】
上記ホウ素含有極性基（例えばボロン酸基）を有するチオールは、例えば、窒素雰囲気下で二重結合を有するチオールとジボランまたはボラン錯体とを反応させた後、アルコール類または水を加えることによって得られる。原料となる二重結合を有するチオールとしては、２−プロペン−１−チオール、２−メチル−２−プロペン−１−チオール、３−ブテン−１−チオール、４−ペンテン−１−チオール等が挙げられる。これらの中でも、２−プロペン−１−チオールおよび２−メチル−２−プロペン−１−チオールが好ましい。ボラン錯体としては、ボラン−テトラヒドロフラン錯体、ボラン−ジメチルスルフィド錯体、ボラン−ピリジン錯体、ボラン−トリメチルアミン錯体、ボラン−トリエチルアミン錯体等が好ましい。これらの中でもボラン−テトラヒドロフラン錯体およびボラン−ジメチルスルフィド錯体が好ましい。ジボランまたはボラン錯体の添加量は、二重結合を有するチオールに対して等量程度が好ましい。反応温度としては室温〜２００℃の範囲が好ましい。溶媒としてはテトラヒドロフラン（ＴＨＦ）、ジグライム等のエーテル系溶媒；ヘキサン、ヘプタン、エチルシクロヘキサン、デカリン等の飽和炭化水素系溶媒等が挙げられる。これらの中でもＴＨＦが好ましい。反応後に添加するアルコール類としては、メタノール、エタノール等の低級アルコールが好ましく、メタノールがより好ましい。
【００５９】
末端にホウ素含有極性基を有する重合体を得るための重合条件としては、アゾ系または過酸化物系の開始剤を用い、重合温度は室温〜１５０℃の範囲が好ましい。上記のホウ素含有極性基を有するチオールの添加量としては単量体１ｇ当たり０．００１〜１ミリモル程度が好ましい。該チオールの添加方法としては、特に制限はないが、単量体として酢酸ビニル、スチレン等の連鎖移動しやすいものを使用する場合は、重合時にチオールを添加することが好ましく、メタクリル酸メチル等の連鎖移動しにくいものを使用する場合は、チオールを最初から加えておくことが好ましい。
【００６０】
上記４）の炭化水素系重合体の形成に用いられる単量体を重合して重合体を得、該重合体中の反応性の部分に、上記極性基（ホウ素含有極性基）を有する単量体を反応により導入する方法としては、次の二つの方法が挙げられる。
【００６１】
４−１）の方法：上記ホウ素含有極性基を有する炭化水素系重合体は、窒素雰囲気下で、炭素−炭素二重結合を有する重合体に、ボラン錯体およびホウ酸トリアルキルエステルを反応させることによってボロン酸ジアルキルエステル基を有する熱可塑性樹脂を得た後、必要に応じて水またはアルコール類を反応させることによって得られる。この方法においては、上記炭素−炭素二重結合を有する重合体の炭素−炭素二重結合にホウ素含有極性基が付加反応により導入される。この製法において、原料として末端に二重結合を有する重合体を使用すれば、末端にホウ素含有極性基を有する炭化水素系重合体が得られ、原料として側鎖または主鎖に二重結合を有する重合体を使用すれば、側鎖にホウ素含有極性基を有する炭化水素系重合体が得られる。
【００６２】
通常のオレフィン系重合体は、その末端にわずかながらも二重結合を有するので、上記の製法の原料として使用できる。その他、炭素−炭素二重結合を有する重合体を得る方法としては、通常のオレフィン系重合体を無酸素条件下、熱分解し、末端に二重結合を有するオレフィン系重合体を得る方法、オレフィン系単量体とジエン系重合体とを原料として、これらの共重合体を得る方法、等が挙げられる。
【００６３】
上記反応に使用するボラン錯体としては、上記２）の方法で記載したボラン錯体が挙げられる。これらの中でも、ボラン−トリメチルアミン錯体およびボラン−トリエチルアミン錯体がより好ましい。ボラン錯体の仕込み量は、熱可塑性樹脂の炭素−炭素二重結合１モルに対して１／３〜１０モルの範囲が好ましい。
【００６４】
上記ホウ酸トリアルキルエステルとしては、トリメチルボレート、トリエチルボレート、トリプロピルボレート、トリブチルボレート等のホウ酸低級アルキルエステルが好ましい。ホウ酸トリアルキルエステルの仕込み量は、熱可塑性樹脂の炭素−炭素二重結合１モルに対して１〜１００モルの範囲が好ましい。溶媒は特に使用する必要はないが、使用する場合は、ヘキサン、ヘプタン、オクタン、デカン、ドデカン、シクロヘキサン、エチルシクロヘキサン、デカリン等の飽和炭化水素系溶媒が好ましい。
【００６５】
反応温度は通常、室温〜３００℃の範囲であり、１００〜２５０℃が好ましく、この範囲の温度で、１分〜１０時間、好ましくは５分〜５時間反応を行うのがよい。
【００６６】
上記の反応によって熱可塑性樹脂に導入されたボロン酸ジアルキルエステル基は、当該分野で一般に使用される方法、例えば、水単独、水と有機溶媒との混合物、または５％ホウ酸水溶液と有機溶媒との混合物を溶媒とし、室温〜１５０℃の条件下で１０分〜２時間加水分解させてボロン酸基とすることができる。また、通常の方法によりアルコール類とエステル交換反応させて任意のボロン酸エステル基とすることができる。さらに、加熱により脱水縮合させてボロン酸無水物基とすることができる。そしてさらに、公知の方法により金属水酸化物または金属アルコラートと反応させてボロン酸塩基とすることができる。
【００６７】
上記のホウ素含有官能基の変換反応に使用される有機溶媒としては、トルエン、キシレン、アセトン、酢酸エチル等が挙げられる。アルコール類としては、メタノール、エタノール、ブタノール等のモノアルコール類；エチレングリコール、プロピレングリコール、１，３−プロパンジオール、１，３−ブタンジオール、ネオペンチルグリコール、グリセリン、トリメチロールエタン、ペンタエリスリトール、ジペンタエリスリトール等の多価アルコール類等が挙げられる。上記金属水酸化物としては、ナトリウム、カリウム等のアルカリ金属の水酸化物等が挙げられる。さらに、上記金属アルコラートとしては、上記金属と上記アルコールとからなる金属アルコラートが挙げられる。これらはいずれも例示したものに限定されるものではない。これらの使用量は、通常ボロン酸ジアルキルエステル基１モルに対して１〜１００モルである。
【００６８】
４−２）の方法：ホウ素含有極性基を有する炭化水素系重合体はまた、当該分野で一般に知られているカルボキシル基を含有する重合体と、ｍ−アミノフェニルベンゼンボロン酸、ｍ−アミノフェニルボロン酸エチレングリコールエステル等のアミノ基含有ボロン酸またはアミノ基含有ボロン酸エステルとを、通常の方法によってアミド化反応させることによって得られる。反応に際しては、カルボジイミド等の縮合剤を用いてもよい。
【００６９】
上記カルボキシル基を含有する熱可塑性樹脂としては、半芳香族ポリエステル樹脂（ＰＥＴ等）、脂肪族ポリエステル樹脂等であって、末端にカルボキシル基を含有する重合体、ポリオレフィン樹脂、スチレン系樹脂、（メタ）アクリル酸エステル系樹脂、ハロゲン化ビニル系樹脂等の重合体に、アクリル酸、メタクリル酸、イタコン酸、シトラコン酸、フマル酸、無水マレイン酸等のカルボキシル基を有する単量体単位が共重合により導入された重合体、前記したオレフィン性二重結合を含有する熱可塑性樹脂に、無水マレイン酸等を付加反応により導入した重合体等が挙げられるが、これらに限定されるものではない。
【００７０】
上記のホウ素含有極性基を有する炭化水素系重合体のメルトフローレート（ＭＦＲ）（２３０℃、荷重２１６０ｇ）は好適には０．１〜１００ｇ／１０分の範囲であり、より好適には０．２〜５０ｇ／１０分の範囲である。
【００７１】
極性基を有する熱可塑性樹脂（Ｂ）として、上述のように、ＥＶＯＨも使用され得る。中でも、エチレン含有量７０〜９９モル％、けん化度４０％以上のエチレン−ビニルアルコール共重合体が好ましい。エチレン含有量はより好適には７２〜９６モル％、さらに好適には７２〜９４モル％である。エチレン含有量が７０モル％に満たない場合、多層容器としたときの耐衝撃剥離性が充分でない場合がある。また、エチレン含有量が９９モル％を超える場合、ＥＶＯＨとの相容性が低下することがある。またけん化度はより好適には４５％以上である。けん化度の上限に特に制限はなく、実質的に１００％のけん化度のものも使用できる。けん化度が４０％に満たない場合、ＥＶＯＨとの相容性が低下することがある。
【００７２】
上記のＥＶＯＨのメルトフローレート（ＭＦＲ）（１９０℃、荷重２１６０ｇ）は好適には０．１ｇ／１０分以上、より好適には０．５ｇ／１０分以上である。また、好適には１００ｇ／１０分以下、より好適には５０ｇ／１０分以下、さらに好適には３０ｇ／１０分以下である。
【００７３】
以上に述べた極性基を有する熱可塑性樹脂（Ｂ）は、単独で使用してもよいし、２種以上を混合して使用してもよい。
【００７４】
本発明の樹脂組成物においては、ＥＶＯＨ（Ａ）と極性基を有する熱可塑性樹脂（Ｂ）との重量比（Ａ／Ｂ）が、５０／５０〜９９．８／０．２であることが必要である。該重量比が５０／５０未満である場合、酸素ガス、炭酸ガスに対するガスバリア性が低下する虞がある。一方、該重量比が９９．８／０．２を超える場合、熱可塑性樹脂（Ｂ）の含有割合が少なくなるため、十分な耐衝撃剥離性が得られない虞がある。該重量比は、好適には５５／４５〜９９／１であり、より好適には６０／４０〜９５／５であり、さらに好適には７０／３０〜９０／１０であり、最適には７５／２５〜８５／１５である。
【００７５】
本発明の樹脂組成物は、本発明の効果を損なわない程度に、上記ＥＶＯＨ（Ａ）、熱可塑性樹脂（Ｂ）以外の熱可塑性樹脂（Ｃ）を含有していてもよい。熱可塑性樹脂（Ｃ）としては、特に限定されず、例えば、次の化合物が挙げられる：ポリエチレン、ポリプロピレン、エチレン−プロピレン共重合体、エチレンまたはプロピレン共重合体（エチレンまたはプロピレンと次の単量体のうちの少なくとも１種との共重合体：１−ブテン、イソブテン、４−メチル−１−ペンテン、１−ヘキセン、１−オクテン等のα−オレフィン；ギ酸ビニル、酢酸ビニル、プロピオン酸ビニル、ビニルブチレート、ビニルオクタノエート、ビニルドデカノエート、ビニルステアレート、ビニルアラキドネート等のカルボン酸ビニルエステル類；ビニルトリメトキシシラン等のビニルシラン系化合物；ビニルピロリドン類等）、ポリ４−メチル−１−ペンテン、ポリ１−ブテン等のポリオレフィン；ポリスチレン、ポリアクリレート等。
【００７６】
本発明の樹脂組成物に含有される熱可塑性樹脂（Ｃ）を選択するときには、該熱可塑性樹脂（Ｃ）と、ＥＶＯＨ（Ａ）および熱可塑性樹脂（Ｂ）との混和性を考慮することが好ましい。これらの樹脂の混和性により、得られる製品のガスバリア性、清浄性、酸素掃去剤としての有効性、機械的特性、製品のテキスチャー等が影響を受けることがある。
【００７７】
本発明の樹脂組成物には、本発明の作用効果が阻害されない範囲内で各種の添加剤を含有させてもよい。このような添加剤の例としては、酸化防止剤、可塑剤、熱安定剤（溶融安定剤）、光開始剤、脱臭剤、紫外線吸収剤、帯電防止剤、滑剤、着色剤、フィラー、乾燥剤、充填剤、顔料、染料、加工助剤、難燃剤、防曇剤、他の高分子化合物等が挙げられる。上記のうち、熱安定剤について、以下に説明する。
【００７８】
上記添加剤のうち、熱安定剤としては、ハイドロタルサイト化合物、高級脂肪族カルボン酸の金属塩の１種または２種以上が用いられる。これらの化合物は、樹脂組成物の製造時において、ゲルやフィッシュアイの発生を防止することができ、長時間の運転安定性をさらに改善することができる。これらの化合物は、樹脂組成物全体の０．０１〜１重量％の割合で含有されるのが好適である。
【００７９】
高級脂肪族カルボン酸の金属塩とは、炭素数８〜２２の高級脂肪酸の金属塩である。炭素数８〜２２の高級脂肪酸としては、ラウリン酸、ステアリン酸、ミリスチン酸等が挙げられる。塩を構成する金属としては、ナトリウム、カリウム、マグネシウム、カルシウム、亜鉛、バリウム、アルミニウム等が挙げられる。このうちマグネシウム、カルシウム、バリウム等のアルカリ土類金属が好適である。このような高級脂肪族カルボン酸の金属塩の中でも、ステアリン酸カルシウム、ステアリン酸マグネシウムが好ましい。
【００８０】
本発明の樹脂組成物の好適なメルトフローレート（ＭＦＲ）（１９０℃、２１６０ｇ荷重下、ＪＩＳ Ｋ７２１０に基く）は０．１〜１００ｇ／１０分、より好適には０．５〜５０ｇ／１０分、さらに好適には１〜３０ｇ／１０分である。本発明の樹脂組成物のメルトフローレートが上記の範囲から外れる場合、溶融成形時の加工性が悪くなる場合が多い。
【００８１】
本発明の樹脂組成物においては、熱可塑性樹脂（Ｂ）からなる粒子がＥＶＯＨ（Ａ）からなるマトリックス中に分散していることが好ましい。このような樹脂組成物からなる成形物は、透明性、ガスバリア性および耐衝撃剥離性が良好である。このとき、熱可塑性樹脂（Ｂ）からなる粒子の平均粒子径は１０μｍ以下であることが好適である。平均粒子径が１０μｍを超える場合には、熱可塑性樹脂（Ｂ）とＥＶＯＨ（Ａ）でなるマトリックスとの界面の面積が小さくなり、ガスバリア性が低下する場合がある。熱可塑性樹脂（Ｂ）粒子の平均粒子径は５μｍ以下がより好ましく、２μｍ以下がさらに好ましい。
【００８２】
本発明の樹脂組成物の各成分は混合され、所望の製品に加工される。本発明の樹脂組成物の各成分を混合する方法は特に限定されなが、工程の簡便さおよびコストの観点から溶融混練法が好ましい。このとき、高い混練度を達成することのできる装置を使用し、各成分を細かく均一に分散させることが、ガスバリア性能、透明性および耐衝撃剥離性を良好にすると共に、ゲル、ブツの発生や混入を防止できる点で好ましい。
【００８３】
混練度の高い装置としては、連続式インテンシブミキサー、ニーディングタイプ二軸押出機（同方向または異方向）、ミキシングロール、コニーダー等の連続型混練機、高速ミキサー、バンバリーミキサー、インテンシブミキサー、加圧ニーダー等のバッチ型混練機、（株）ＫＣＫ製のＫＣＫ混練押出機等の石臼のような摩砕機構を有する回転円板を使用した装置、一軸押出機に混練部（ダルメージ、ＣＴＭ等）を設けたもの、リボンブレンダー、ブラベンダーミキサー等の簡易型の混練機等を挙げることができる。これらの中でも、連続型混練機が好ましい。市販されている連続式インテンシブミキサーとしては、Ｆａｒｒｅｌ社製ＦＣＭ、（株）日本製鋼所製ＣＩＭ、（株）神戸製鋼所製ＫＣＭ、ＬＣＭ、ＡＣＭ等が挙げられる。これらの混練機の下に一軸押出機を設置し、混練と押出ペレット化を同時に実施する装置を採用することが好ましい。また、ニーディングディスクまたは混練用ロータを有する二軸混練押出機としては、例えば（株）日本製鋼所製ＴＥＸ、Ｗｅｒｎｅｒ＆Ｐｆｌｅｉｄｅｒｅｒ社製ＺＳＫ、東芝機械（株）製ＴＥＭ、池貝鉄工（株）製ＰＣＭ等が挙げられる。
【００８４】
これらの連続型混練機においては、ローター、ディスクの形状が重要な役割を果たす。特にミキシングチャンバとローターチップまたはディスクチップとの隙間（チップクリアランス）は重要で、狭すぎても広すぎても分散性の良好な混合物は得られない。チップクリアランスとしては１〜５ｍｍが最適である。
【００８５】
混練機のローターの回転数は、通常１００〜１２００ｒｐｍであり、好ましくは１５０〜１０００ｒｐｍであり、より好ましくは２００〜８００ｒｐｍである。また、混練機チャンバー内径（Ｄ）は通常３０ｍｍ以上であり、好ましくは５０〜４００ｍｍである。さらに、混練機のチャンバー長さ（Ｌ）と内径（Ｄ）との比Ｌ／Ｄは、４〜３０が好適である。混練機は１機でもよいし、また２機以上を連結して用いることもできる。
【００８６】
混練温度は、通常５０〜３００℃の範囲である。該樹脂組成物の酸化防止のためには、ホッパー口を窒素シールし、低温で押出すことが好ましい。混練時間は、長い方が良い結果を得られるが、樹脂組成物の酸化防止および生産効率の観点から、通常１０〜６００秒であり、好ましくは１５〜２００秒であり、より好ましくは１５〜１５０秒である。
【００８７】
本発明の樹脂組成物は、成形方法を適宜採用することによって、種々の成形物、例えば、フィルム、シート、容器その他の包装材料等に成形することができる。このとき、本発明の樹脂組成物を一旦ペレットとしてから成形に供してもよいし、樹脂組成物の各成分をドライブレンドして、直接成形に供してもよい。
【００８８】
成形方法および成形物としては、例えば、溶融押出成形によりフィルム、シート、パイプ等に、射出成形により容器形状に、また中空成形によりボトル状等中空容器に成形することができる。中空成形としては、押出成形によりパリソンを成形し、これをブローして成形を行う押出中空成形と、射出成形によりプリフォームを成形し、これをブローして成形を行う射出中空成形が好ましい。
【００８９】
本発明においては、上記成形により得られる成形物は単層であってもよいが、機械的特性、水蒸気バリア性、さらなる酸素バリア性等の特性を付与するという観点から、他の層と積層して多層構造体として用いることが好ましい。
【００９０】
多層構造体の層構成としては、本発明の樹脂組成物以外の樹脂からなる層をｘ層、本発明の樹脂組成物層をｙ層、接着性樹脂層をｚ層とすると、ｘ／ｙ、ｘ／ｙ／ｘ、ｘ／ｚ／ｙ、ｘ／ｚ／ｙ／ｚ／ｘ、ｘ／ｙ／ｘ／ｙ／ｘ、ｘ／ｚ／ｙ／ｚ／ｘ／ｚ／ｙ／ｚ／ｘ等が例示されるが、これらに限定されるものではない。複数のｘ層を設ける場合は、その種類は同じであっても異なっていてもよい。また、成形時に発生するトリム等のスクラップからなる回収樹脂を用いた層を別途設けてもよいし、回収樹脂を他の樹脂からなる層にブレンドしてもよい。多層構造体の各層の厚み構成は、特に限定されるものではないが、成形性およびコスト等の観点から、全層厚みに対するｙ層の厚み比は２〜２０％が好適である。
【００９１】
上記のｘ層に使用される樹脂としては、加工性等の観点から熱可塑性樹脂が好ましい。かかる熱可塑性樹脂としては、次の樹脂が挙げられるが、特にこれらに限定されない：ポリエチレン、ポリプロピレン、エチレン−プロピレン共重合体、エチレンまたはプロピレン共重合体（エチレンまたはプロピレンと次の単量体の少なくとも１種との共重合体：１−ブテン、イソブテン、４−メチル−１−ペンテン、１−ヘキセン、１−オクテン等のα−オレフィン；イタコン酸、メタクリル酸、アクリル酸、無水マレイン酸等の不飽和カルボン酸、その塩、その部分または完全エステル、そのニトリル、そのアミド、その無水物；ギ酸ビニル、酢酸ビニル、プロピオン酸ビニル、ビニルブチレート、ビニルオクタノエート、ビニルドデカノエート、ビニルステアレート、ビニルアラキドネート等のカルボン酸ビニルエステル類；ビニルトリメトキシシラン等のビニルシラン系化合物；不飽和スルホン酸またはその塩；アルキルチオール類；ビニルピロリドン類等）、ポリ４−メチル−１−ペンテン、ポリ１−ブテン等のポリオレフィン；ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート等のポリエステル；ポリε−カプロラクタム、ポリヘキサメチレンアジパミド、ポリメタキシリレンアジパミド等のポリアミド；ポリ塩化ビニリデン、ポリ塩化ビニル、ポリスチレン、ポリアクリロニトリル、ポリカーボネート、ポリアクリレート等。かかる熱可塑性樹脂層は無延伸のものであってもよいし、一軸もしくは二軸に延伸または圧延されているものであっても構わない。
【００９２】
これらの熱可塑性樹脂のうち、ポリオレフィンは耐湿性、機械的特性、経済性、ヒートシール性等の点で、また、ポリエステルは機械的特性、耐熱性等の点で好ましい。
【００９３】
一方、ｚ層に使用される接着性樹脂としては、各層間を接着できるものであれば特に限定されず、ポリウレタン系またはポリエステル系の一液型または二液型硬化性接着剤、カルボン酸変性ポリオレフィン樹脂等が好適に用いられる。カルボン酸変性ポリオレフィン樹脂は、不飽和カルボン酸またはその無水物（無水マレイン酸等）を共重合成分として含むオレフィン系重合体または共重合体；あるいは不飽和カルボン酸またはその無水物をオレフィン系重合体または共重合体にグラフトさせて得られるグラフト共重合体である。
【００９４】
これらの中でも、カルボン酸変性ポリオレフィン樹脂がより好ましい。特に、ｘ層がポリオレフィン樹脂である場合、ｙ層との接着性が良好となる。かかるカルボン酸変性ポリオレフィン系樹脂の例としては、ポリエチレン｛低密度ポリエチレン（ＬＤＰＥ）、直鎖状低密度ポリエチレン（ＬＬＤＰＥ）、超低密度ポリエチレン（ＶＬＤＰＥ）｝、ポリプロピレン、共重合ポリプロピレン、エチレン−酢酸ビニル共重合体、エチレン−（メタ）アクリル酸エステル（メチルエステルまたはエチルエステル）共重合体等をカルボン酸変性したものが挙げられる。
【００９５】
多層構造体を得る方法としては、押出ラミネート法、ドライラミネート法、共射出成形法、共押出成形法等が例示されるが、特に限定されるものではない。共押出成形法としては、共押出ラミネート法、共押出シート成形法、共押出インフレーション成形法、共押出ブロー成形法等を挙げることができる。
【００９６】
このようにして得られた多層構造体のシート、フィルム、パリソン等を、含有される樹脂の融点以下の温度で再加熱し、絞り成形等の熱成形法、ロール延伸法、パンタグラフ式延伸法、インフレーション延伸法、ブロー成形法等により一軸または二軸延伸して、延伸された成形物を得ることもできる。
【００９７】
本発明の樹脂組成物は適切な樹脂を選択することにより透明性が良好となる。従って、積層する他の樹脂として透明性が良好な樹脂を選択することにより、内容物を視認しやすい包装容器を得られる。かかる観点から、本発明の樹脂組成物層を有する多層構造体のヘイズ値は、１０％以下であることが好ましく、５％以下がより好ましく、３％以下がさらに好ましい。
【００９８】
上記の多層構造体を用いた成形物は各種用途に用いられる。とりわけ、本発明の多層構造体の効果は、多層容器としたときに大きく発揮される。かかる包装容器の内でも透明性に対する要求性能が厳しく、本発明の樹脂組成物を使用することの有用性が大きい態様として、以下の２種の態様が挙げられる。すなわち、一つは本発明の樹脂組成物からなる層を含み、全層厚みが３００μｍ以下である多層フィルムからなる容器であり、他の一つは本発明の樹脂組成物からなる層およびＰＥＳ層をそれぞれ少なくとも１層含む多層容器である。以下、それらの実施態様について順次説明する。
【００９９】
本発明の樹脂組成物からなる層を含み、全層厚みが３００μｍ以下である多層フィルムからなる容器は、全体層厚みが比較的薄い多層構造体からなるフレキシブルな容器であり、通常パウチ等の形態に加工されている。この容器はガスバリア性に優れ、かつ製造が簡便であるので、酸素に対し感受性が高く劣化し易い製品の包装に極めて有用である。
【０１００】
一般に良好な透明性が要求される容器としては、多層構造体を構成する各樹脂層の厚みが薄く、全体としての厚みの薄い容器が製造される。例えば、ポリオレフィン等の結晶性の樹脂を用いる場合に、厚みが大きい場合には、結晶による散乱に由来して透明性が悪化する場合が多いのに対し、厚みの薄い容器であれば、良好な透明性が得られる。また一般に、無延伸で結晶化している樹脂は透明性が不良であっても、延伸配向して結晶化した樹脂は透明性が良好となる。かかる一軸または二軸に延伸されたフィルムは通常厚みが薄く、この点からも厚みの薄い多層構造体が良好な透明性を与える場合が多い。
【０１０１】
本発明の樹脂組成物は適切な樹脂を選択することにより透明性が良好となる。従って、透明性が要求されることの多い、厚みの薄い多層フィルムからなる容器に好適に使用することが可能である。このような薄いフィルムにおいては経時的に透明性が悪化してもその程度は小さい。このような多層フィルムの厚みは、特に限定されないが、透明性およびフレキシブル性を維持するという観点から好適には３００μｍ以下であり、より好適には２５０μｍ以下であり、さらに好適には２００μｍ以下である。一方、容器としての機械的特性を考慮すると、全層厚みは好適には１０μｍ以上であり、より好適には２０μｍ以上であり、さらに好適には３０μｍ以上である。
【０１０２】
上記の多層容器を多層フィルムから製造する場合、該多層フィルムの製造方法に特に制限はなく、例えば、本発明の樹脂組成物層と他の熱可塑性樹脂層とをドライラミネート、共押出ラミネート等の方法で積層することによって多層フィルムを得ることができる。
【０１０３】
ドライラミネートする場合には、無延伸フィルム、一軸延伸フィルム、二軸延伸フィルム、圧延フィルム等が使用可能である。これらの中でも、二軸延伸ポリプロピレンフィルム、二軸延伸ポリエチレンテレフタレートフィルム、二軸延伸ポリε−カプロラクタムフィルムが、機械的強度の観点から好ましく、防湿性も考慮すると、二軸延伸ポリプロピレンフィルムが特に好ましい。無延伸フィルムまたは一軸延伸フィルムを使用する場合、積層した後に多層フィルムを再加熱し、絞り成形等の熱成形法、ロール延伸法、パンタグラフ式延伸法、インフレーション延伸法等により一軸または二軸延伸することによって、延伸された多層フィルムを得ることもできる。
【０１０４】
得られる多層容器を密封するために、多層フィルムの製造段階において、少なくとも一方の最外層表面にヒートシール可能な樹脂からなる層を設けることも好ましい。かかる樹脂としては、ポリエチレン、ポリプロピレン等のポリオレフィンを挙げることができる。
【０１０５】
こうして得られた多層フィルムは、例えば袋状に加工され、内容物を充填するための包装容器とすることができる。フレキシブルで簡便であり、かつ透明性に優れるので、酸素の存在により劣化しやすい内容物、特に食品等の包装に極めて有用である。
【０１０６】
本発明の樹脂組成物からなる層およびＰＥＳ層をそれぞれ少なくとも１層含む多層容器は、ガスバリア性に優れ、さらに適切な樹脂を選択することにより透明性が良好となる。そのため、袋状容器、カップ状容器、中空成形容器等の種々の形態で使用される。これらの中でも、中空成形容器、特にボトルが重要である。
【０１０７】
ＰＥＳからなるボトルは、現在広く飲料容器として使用されている。かかる用途においては内容物の劣化を防ぐ必要があるとともに、内容物である飲料を消費者が充分に視認できることが要求されている。しかも、例えばビールのような酸素による風味の劣化を極めて受けやすい内容物を充填する場合には、極めて高度なガスバリア性を有することが望まれる。
【０１０８】
本発明の樹脂組成物からなる層およびＰＥＳ層をそれぞれ少なくとも１層含む多層容器は、高い透明性を得ることが可能であり、内容物の品質の保持性能が極めて優れているので、かかる用途に最適である。多層容器の層構成としては、樹脂組成物層とＰＥＳ層との間に接着性樹脂層を配置してもよいが、ＰＥＳ層が樹脂組成物層の両面に直接接触するように配置されてなる多層容器は、より高い透明性を得ることが可能であり、かつ樹脂組成物層とＰＥＳ層との間の耐衝撃剥離性に優れるという本発明の効果を充分に奏し得る観点から、特に好ましい。
【０１０９】
上記本発明の樹脂組成物からなる層およびＰＥＳ層からなる本発明の多層容器に用いられるＰＥＳとしては、芳香族ジカルボン酸またはそれらのアルキルエステルと、ジオールとを主成分とする縮合重合体が用いられる。特に本発明の目的を達成するには、エチレンテレフタレート成分を主とするＰＥＳが好ましい。具体的には、テレフタル酸単位とエチレングリコール単位との合計割合（モル％）が、ＰＥＳを構成する全構造単位の合計モル数に対して、７０モル％以上であることが好ましく、９０モル％以上がより好ましい。テレフタル酸単位とエチレングリコール単位の合計割合が７０モル％未満であると、得られるＰＥＳが非晶性となり、機械的強度が不足する上に、延伸して容器とした後に内容物を加熱充填（ホットフィル）すると、熱収縮が大きく使用に耐えない虞がある。また、樹脂内に含有されるオリゴマーを低減するために固相重合を行うと、樹脂の軟化による膠着が生じやすく、生産が困難になる虞がある。
【０１１０】
上記ＰＥＳは、必要に応じてテレフタル酸単位およびエチレングリコール単位以外の二官能化合物単位を、上記の問題が発生しない範囲において含有することができる。その割合（モル％）としては、ＰＥＳを構成する全構造単位の合計モル数に対して、３０モル％以下であることが好ましく、２０モル％以下がより好ましく、１０モル％以下がさらに好ましい。このような二官能化合物単位としては、ジカルボン酸単位、ジオール単位、ヒドロキシカルボン酸単位等が挙げられ、脂肪族、脂環式、芳香族のいずれでもよい。具体的には、ネオペンチルグリコール単位、シクロヘキサンジメタノール単位、シクロヘキサンジカルボン酸単位、イソフタル酸単位、ナフタレンジカルボン酸単位等が挙げられる。
【０１１１】
これらの中でも、イソフタル酸単位は、得られたＰＥＳを用いた場合、良好な成形物を得ることのできる製造条件が広く、成形性に優れるため、不良品率が低いという利点を有する。結晶化速度の抑制により、成形品の白化を防止できる点からも好ましい。また、１，４−シクロヘキサンジメタノール単位または１，４−シクロヘキサンジカルボン酸単位は、得られる成形物の落下時の強度が一層優れるという点から好ましい。さらに、ナフタレンジカルボン酸単位は、得られるＰＥＳのガラス転移温度が上昇し、耐熱性が向上する上に、紫外線を吸収する能力が付与されるので好ましく、内容物が紫外線による劣化を生じやすい場合に特に有用である。例えば、ビールのように内容物が酸化によっても、紫外線によっても劣化しやすいものである場合に特に有用である。
【０１１２】
ＰＥＳの製造に際して重縮合触媒を使用する場合は、ＰＥＳの製造に通常用いられている触媒を使用することができる。例えば、三酸化アンチモン等のアンチモン化合物；二酸化ゲルマニウム、ゲルマニウムテトラエトキシド、ゲルマニウムテトラ−ｎ−ブトキシド等のゲルマニウム化合物；テトラメトキシチタン、テトラエトキシチタン、テトラ−ｎ−プロポキシチタン、テトライソプロポキシチタン、テトラブトキシチタン等のチタン化合物；ジ−ｎ−ブチル錫ジラウレート、ジ−ｎ−ブチル錫オキサイド、ジブチル錫ジアセテート等の錫化合物等を使用することができる。これらの触媒は単独で使用しても、２種類以上を組み合わせて使用してもよい。重縮合触媒の使用量としては、ジカルボン酸成分の重量に基いて０．００２〜０．８重量％の範囲が好ましい。
【０１１３】
これらの中でも、触媒コストの面からはアンチモン化合物が好ましく、三酸化アンチモンが特に好ましい。一方、得られるＰＥＳの色調が良好となるという面からはゲルマニウム化合物が好ましく、二酸化ゲルマニウムが特に好ましい。また、成形性の観点からは、ゲルマニウム化合物がアンチモン化合物よりも好ましい。アンチモン化合物を触媒とした重合反応により得られるＰＥＳは、ゲルマニウム化合物を触媒として重合したＰＥＳよりも結晶化速度が速く、射出成形時またはブロー成形時に、加熱による結晶化が進行しやすく、結果として得られたボトルに白化が生じて透明性が損なわれる場合がある。また、延伸配向性が低下して、賦形性が悪化する場合もある。このように、良好な成形物を得ることのできる製造条件の範囲が狭くなり、不良品率が上昇しやすくなる傾向にある。
【０１１４】
特に、本発明に使用されるＰＥＳとして、副生するジエチレングリコール単位以外の共重合成分を含まないポリエチレンテレフタレートを使用する場合には、該ＰＥＳを製造する際に、結晶化速度を抑えるためにゲルマニウム化合物を触媒として用いることが好ましい。
【０１１５】
上記樹脂組成物からなる層およびＰＥＳ層をそれぞれ少なくとも１層含む、本発明の多層容器の製造方法は特に限定されるものではないが、共射出ブロー成形を用いることが生産性等の観点から好適である。共射出ブロー成形においては、共射出成形によって得られた容器前駆体（パリソン）を延伸ブロー成形することにより容器が製造される。
【０１１６】
共射出成形においては、通常、多層構造体の各層を構成すべき樹脂を２台またはそれ以上の射出シリンダーより同心円状のノズル内に導き、同時にまたはタイミングをずらして交互に、単一の金型内に射出し、１回の型締め操作を行うことにより成形が行われる。例えば（１）先に内外層用のＰＥＳ層を射出し、次いで、中間層となる樹脂組成物を射出して、ＰＥＳ／樹脂組成物／ＰＥＳの３層構成の成形容器を得る方法、（２）先に内外層用のＰＥＳ層を射出し、次いで樹脂組成物を射出して、それと同時にまたはその後にＰＥＳ層を再度射出し、ＰＥＳ／樹脂組成物／ＰＥＳ／樹脂組成物／ＰＥＳの５層構成の成形容器を得る方法等によりパリソンが製造されるが、これらの製造方法に限定されるものではない。また、上記層構成において、樹脂組成物層とＰＥＳ層との間に、必要に応じて接着性樹脂層を配置してもよい。
【０１１７】
射出成形の条件としては、ＰＥＳは２５０〜３３０℃の温度範囲で射出することが好ましく、２７０〜３２０℃がより好ましく、２８０〜３１０℃がさらに好ましい。ＰＥＳの射出温度が２５０℃未満である場合、ＰＥＳが十分に溶融せず、成形物に未溶融物（フィッシュアイ）が混入し外観不良を生じ、同時に成形物の機械的強度の低下の原因となる虞がある。また、極端な場合はスクリュートルクが上昇し、成形機の故障を引き起こす虞がある。一方、ＰＥＳの射出温度が３３０℃を超える場合、ＰＥＳの分解が著しくなり、分子量低下による成形物の機械的強度の低下を引き起こす虞がある。また、分解時に生じるアセトアルデヒド等のガスにより成形物に充填する物質の性質を損なうだけでなく、分解時に生じるオリゴマーにより金型の汚れが激しくなり成形物の外観を損なう虞がある。
【０１１８】
樹脂組成物は１７０〜２５０℃の温度範囲で射出することが好ましく、１８０〜２４０℃がより好ましく、１９０〜２３０℃がさらに好ましい。樹脂組成物の射出温度が１７０℃未満である場合、樹脂組成物が十分に溶融せず、成形物に未溶融物（フィッシュアイ）が混入し外観不良を生じる虞がある。また、極端な場合はスクリュートルクが上昇し、成形機の故障を引き起こす虞がある。一方、樹脂組成物の射出温度が２５０℃を超える場合、熱可塑性樹脂（Ｂ）の酸化が進行し、樹脂組成物のガスバリア性および酸素掃去機能が低下する虞がある。同時に、着色やゲル化物による成形物の外観不良が生じ、あるいは分解ガスやゲル化物により流動性が不均一となりもしくは阻害されて、樹脂組成物層の欠落部分を生じることもある。極端な場合には、ゲル化物の発生により、射出成形が不可能となる。溶融時の酸化の進行を抑制するためには、原料供給ホッパーを窒素でシールすることも好ましい。
【０１１９】
なお樹脂組成物は、前もって原料成分を溶融配合したペレットの形で成形機に供給してもよいし、ドライブレンドした各原料成分を成形機に供給してもよい。
【０１２０】
ＰＥＳおよび樹脂組成物が流入するホットランナー部分の温度は２２０〜３００℃の範囲が好ましく、２４０〜２８０℃がより好ましく、２５０〜２７０℃がさらに好ましい。ホットランナー部分の温度が２２０℃未満である場合、ＰＥＳが結晶化してホットランナー部分で固化するため、成形が困難となる場合がある。一方、ホットランナー部分の温度が３００℃を超える場合、樹脂組成物の酸化が進行し、着色やゲル化物による成形物の外観不良が生じ、あるいは分解ガスやゲル化物により流動性が不均一となりもしくは阻害されて、樹脂組成物層の欠落部分を生じることもある。極端な場合には、ゲル化物の発生により、射出成形が不可能となる。
【０１２１】
金型温度としては、０〜７０℃の範囲が好ましく、５〜５０℃がより好ましく、１０〜３０℃がさらに好ましい。これにより、パリソンのＰＥＳおよび樹脂組成物の結晶化が抑制され、均一な延伸性が確保されて、得られる多層容器の耐層間剥離性および透明性が向上し、形状の安定した成形物を得ることができる。金型温度が０℃未満である場合、金型の結露によりパリソンの外観が損なわれ、良好な成形物が得られない虞がある。また、金型温度が７０℃を超える場合、パリソンのＰＥＳおよび樹脂組成物の結晶化が抑制されず、延伸性が不均一となり、得られる成形物の耐層間剥離性および透明性が低下する上、意図した形に賦形された成形物を得ることが困難となる。
【０１２２】
こうして得られたパリソンにおいては、総厚みが２〜５ｍｍ、樹脂組成物層の厚みが合計で１０〜５００μｍであることが好ましい。
【０１２３】
上記のパリソンは、高温の状態で直接、またはブロックヒーター、赤外線ヒーター等の発熱体を用いて再加熱された後、延伸ブロー工程に送られる。加熱されたパリソンを、延伸ブロー工程において縦方向に１〜５倍に延伸した後、圧縮空気等で１〜４倍に延伸ブロー成形することにより、本発明の多層射出ブロー成形容器を製造することができる。パリソンの温度は、７５〜１５０℃が好ましく、８５〜１４０℃がより好ましく、９０〜１３０℃がさらにより好ましく、９５〜１２０℃が最も好ましい。パリソンの温度が１５０℃を超えると、ＰＥＳが結晶化しやすくなり、得られる容器が白化して外観が損なわれたり、容器の層間剥離が増加する場合がある。一方、パリソンの温度が７５℃未満であると、ＰＥＳにクレーズが生じ、パール調になって透明性が損なわれる場合がある。
【０１２４】
こうして得られる多層容器の胴部の総厚みは、一般的には１００〜２０００μｍ、好適には１５０〜１０００μｍであり、用途に応じて使い分けられる。このときの樹脂組成物層の合計厚みは、２〜２００μｍの範囲であることが好ましく、５〜１００μｍがより好ましい。
【０１２５】
このようにして本発明の樹脂組成物からなる層およびＰＥＳ層からなる多層容器が得られる。この容器は高い透明性を得ることが可能であり、かつガスバリア性および耐衝撃剥離性に極めて優れる。従って、酸素の存在により劣化しやすい内容物、例えば、食品、医薬品等の容器として有用である。特にビール等の飲料の容器として極めて有用である。
【０１２６】
【実施例】
以下に本発明を実施例により具体的に説明するが、本発明はそれにより何ら限定されるものではない。
【０１２７】
ＥＶＯＨ（Ａ）として、表１に示す構成、物性を示すものを使用した。ただし、ＥＶＯＨ２は以下の様にして製造した。
【０１２８】
（ＥＶＯＨ２の製造）
エチレン含有量３２モル％、けん化度９９．５モル％のＥＶＯＨ８０重量部、エチレン含有量４４モル％、けん化度９６．５モル％のＥＶＯＨ２０重量部をドライブレンドした。次に、３０ｍｍφ二軸押出機（（株）日本製鋼所ＴＥＸ−３０ＳＳ−３０ＣＲＷ−２Ｖ）を使用して、押出機温度２１０℃（樹脂温度２２０℃）、スクリュー回転数３００ｒｐｍ、押出樹脂量２５ｋｇ／時間の条件で押出し、ペレット化した。最後に、８０℃で１６時間除湿空気下で乾燥を行い、ＥＶＯＨ２を得た。
【０１２９】
【表１】

【０１３０】
官能基を有する熱可塑性樹脂（Ｂ）として、表２に示すものを使用した。ただし、Ｂ−１は以下の様にして製造した。
【０１３１】
スチレン−水添ブタジエン−スチレントリブロック共重合体Ｂ−３（重量平均分子量１００４００、スチレン／水添ブタジエン＝１８／８２（重量比）、ブタジエン単位の１，２−結合／１，４−結合モル比＝４７／５３、ブタジエン単位の水添率９７％、二重結合量４３０μｅｑ／ｇ、メルトインデックス５ｇ／１０分（２３０℃、２１６０ｇ荷重）、密度０．８９ｇ／ｃｍ^３）を、投入口を１Ｌ／分の窒素で置換しながら７ｋｇ／時の速度で二軸押出機に供給した。次に、液体フィーダー１よりボラン−トリエチルアミン錯体（ＴＥＡＢ）とホウ酸１，３−ブタンジオールエステル（ＢＢＤ）の混合液（ＴＥＡＢ／ＢＢＤ＝２９／７１、重量比）を０．６ｋｇ／時の速度で、液体フィーダー２より１，３−ブタンジオールを０．４ｋｇ／時の速度で供給し、連続的に混練した。混練の間、ベント１およびベント２のゲージが約２０ｍｍＨｇを示すように圧力を調節した。その結果、吐出口から７ｋｇ／時の速度で、ボロン酸１，３−ブタンジオールエステル基（ＢＢＤＥ）を含有するトリブロック共重合体（Ｂ−１）が得られた。Ｂ−１のボロン酸１，３−ブタンジオールエステル基含有量は２１０μｅｑ／ｇであった。
【０１３２】
なお、反応に使用した二軸押出機の構成、運転条件は下記のとおりである。

【０１３３】
【表２】

【０１３４】
実施例１
Ａとして表１に示すＥＶＯＨ１を、Ｂとして表２に示すＢ−１をそれぞれ使用した。８０重量部のＥＶＯＨ１と２０重量部のＢ−１をドライブレンドし、３０ｍｍφ二軸押出機（（株）日本製鋼所製ＴＥＸ−３０ＳＳ−３０ＣＲＷ−２Ｖ）を用い、押出機温度２１０℃、スクリュー回転数３００ｒｐｍ、押出樹脂量２５ｋｇ／時間の条件で押出してペレット化し、８０℃で１６時間除湿空気下で乾燥を行い樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は１．６ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、Ｂ−１のおおむね１μｍ以下の粒子が、ＥＶＯＨ１からなるマトリックス中に分散していた。結果を表３に示す。
【０１３５】
多層容器の製造にあたり、熱可塑性ポリエステルとして、二酸化ゲルマニウムを触媒とした重合により得られたポリエチレンテレフタレート（ＰＥＴ）を使用した。該ＰＥＴにおけるテレフタル酸単位、エチレングリコール単位、およびジエチレングリコール単位の含有率はそれぞれ５０．０モル％、４８．９モル％、１．１モル％であった。また、極限粘度は０．８３ｄｌ／ｇ、融点およびガラス転移温度はそれぞれ２５２℃、８０℃であった。
【０１３６】
次に、上記樹脂組成物ペレットと上記ＰＥＴを原料とし、ＫＯＲＴＥＣ／ＨＵＳＫＹ製共射出成形機（ＳＬ１６０型４個取り）を使用して、多層容器におけるＰＥＴ層と樹脂組成物層の重量比が９５／５となるように、射出速度および射出量を調節し、共射出成形を行って、ＰＥＴ／樹脂組成物／ＰＥＴの２種３層の有底パリソンを製造した。このとき、ＰＥＴ側射出機の温度は２８０℃、樹脂組成物側射出機の温度は２１０℃、ＰＥＴと樹脂組成物とが合流するホットランナーブロック部の温度は２７０℃、射出金型のコア温度は１０℃、射出金型のキャビティー温度は１０℃とした。
【０１３７】
その後、ＣＲＵＰＰ ＣＯＲＰＯＰＬＡＳＴ ＭＡＳＣＨＩＮＥＮＢＡＵ製延伸ブロー成形機（ＬＢ０１型５３０ｍＬ１個取り）を使用して、有底パリソンの表面温度を１０５℃に加熱し、延伸ブロー成形を行って、２種３層の多層容器を得た。得られた多層容器を胴部で切断し、各層の厚みを測定した結果、内層ＰＥＴ１４０μｍ、中間層樹脂組成物３０μｍ、外層ＰＥＴ１９０μｍであった。この多層容器の衝撃剥離発生率、ヘイズ値および酸素透過速度を以下のようにして測定した。
【０１３８】
衝撃剥離発生率： 容器に水を充填し、常圧下で密栓した後、６０ｃｍの高さから、９０°の角度を持った長さ２０ｃｍの三角形の台の上に、台の角部が容器胴部の中央に当たるように、容器胴部を水平にして一回のみ自然落下させた。１００本の容器について試験を行い、剥離を生じた容器の本数（Ｎｄ）から下記式を用いてデラミ発生率（Ｒｄ）を算出した。
Ｒｄ（％） ＝ （Ｎｄ／１００）×１００
【０１３９】
ヘイズ値： 容器胴部中央を円周上に４分割した４箇所について、ポイック積分球式光線透過率・全光線反射率計（村上色彩技術研究所製「ＨＲ−１００型」）を使用し、ＡＳＴＭ Ｄ１００３−６１に準じて内部ヘイズ値を測定し、その平均値を容器のヘイズ値とした。
【０１４０】
酸素透過速度： 容器の形態のままで、容器外側を２０℃−６５％ＲＨ、容器内側を２０℃−１００％ＲＨに温湿度調節した後、酸素透過速度測定装置（モダンコントロール社製、ＯＸ−ＴＲＡＮ−１０／５０Ａ）を使用して、容器１個当たりの酸素透過速度（ｍｌ／（ｃｏｎｔａｉｎｅｒ・ｄａｙ・ａｔｍ））を測定した。以上の結果をまとめて表４に示す。
【０１４１】
実施例２
Ａとして、ＥＶＯＨ１の代わりにＥＶＯＨ２を使用した以外は、実施例１と同様にして樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は１．７ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、Ｂ−１のおおむね１μｍ以下の粒子が、ＥＶＯＨ２からなるマトリックス中に分散していた。結果を表３に示す。
その後、実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４２】
実施例３
Ｂとして、Ｂ−１の代わりに無水マレイン酸変性ポリエチレン（Ｂ−２、三井化学株式会社製「アドマー」ＳＦ−７００）を使用した以外は、実施例１と同様にして樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は１．２ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、Ｂ−２のおおむね１μｍ以下の粒子が、ＥＶＯＨ１からなるマトリックス中に分散していた。結果を表３に示す。
その後、実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４３】
実施例４
Ｂとして、Ｂ−１の代わりにＢ−２を使用した以外は、実施例２と同様にして樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は１．２ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、Ｂ−２のおおむね１μｍ以下の粒子が、ＥＶＯＨ２からなるマトリックス中に分散していた。結果を表３に示す。
その後、実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４４】
比較例１
樹脂組成物の代わりにＥＶＯＨ１を使用した（表３）。実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４５】
比較例２
樹脂組成物の代わりにＥＶＯＨ２を使用した（表３）。実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４６】
比較例３
３０重量部のＥＶＯＨ２と７０重量部のＢ−１をドライブレンドし、実施例１と同様にして樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は５．８ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、ＥＶＯＨ２のおおむね１μｍ以下の粒子が、Ｂ−１からなるマトリックス中に分散していた。結果を表３に示す。
その後、実施例１と同様にして多層容器の製造を試みたが、得られた樹脂組成物ペレットは粘着性が極めて高く、滑剤を添加しても射出成形機への安定した供給が困難であったため、実用に耐えられないと判断して他の評価を取り止めた。
【０１４７】
比較例４
Ｂとして、Ｂ−１の代わりにＢ−１の原料であるＢ−３を使用した以外は、実施例２と同様にして樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は１．８ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、Ｂ−３のおおむね５μｍ以下の粒子が、ＥＶＯＨ２からなるマトリックス中に分散していた。結果を表３に示す。
その後、実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４８】
比較例５
Ｂとして、Ｂ−１の代わりに直鎖状低密度ポリエチレン（Ｂ−４、三井化学株式会社製「ウルトゼックス」３０２１Ｆ）を使用した以外は、実施例２と同様にして樹脂組成物ペレットを得た。この樹脂組成物のメルトフローレート（１９０℃、２１６０ｇ荷重）は２．１ｇ／１０分であった。樹脂組成物ペレットの破断面を電子顕微鏡で観察したところ、Ｂ−４のおおむね１０μｍ以下の粒子が、ＥＶＯＨ１からなるマトリックス中に分散していた。結果を表３に示す。
その後、実施例１と同様にして共射出延伸ブロー成形を行い、２種３層の多層容器を得て、衝撃剥離発生率、ヘイズ値および酸素透過速度を測定した。結果を表４に示す。
【０１４９】
【表３】

【０１５０】
【表４】

【０１５１】
【発明の効果】
本発明の樹脂組成物は、ＥＶＯＨの有するガスバリア性等の特性を維持し、かつ、ポリエステル樹脂との接着性に優れているので、該樹脂組成物とポリエステル樹脂とからなる多層構造体、とりわけ、共射出延伸ブロー成形多層容器は、耐衝撃剥離性に優れている。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a resin composition having excellent gas barrier properties against oxygen and carbon dioxide, and excellent adhesion to a polyester resin. The present invention also relates to a multilayer container using the resin composition, which is excellent in gas barrier properties against oxygen, carbon dioxide gas and the like, and excellent in impact peeling resistance.
[0002]
[Prior art]
Thermoplastic polyester (hereinafter sometimes abbreviated as PES) containers are excellent in various properties such as transparency, mechanical properties, and flavor barrier properties, and are less likely to elute residual monomers and harmful additives. Because of its excellent properties and safety, it is used in a wide range of fields. In particular, a multilayer container combining PES and an ethylene-vinyl alcohol copolymer having good gas barrier properties (hereinafter, sometimes abbreviated as EVOH) can provide a container having a good appearance with a simple device, Since it has the characteristics of both PES and EVOH, it is expected to expand its use as a container for beverages, foods, cosmetics, etc., and improves the impact peeling resistance and transparency, which have been issues in multilayer containers. Various proposals have been made.
[0003]
For example, it is known that a multilayer container composed of PES and partially saponified EVOH and obtained by co-injection stretch blow molding has excellent impact peel resistance and transparency (for example, see Patent Document 1). The multilayer container was a breakthrough in that it had impact peeling resistance even though no adhesive resin was used between PES and EVOH. However, in the multilayer container, since the partially saponified EVOH is used, the gas barrier property and the thermal stability may be uneasy. In order to solve this problem, in the multilayer container, a multilayer container comprising an EVOH mixture having two or more different melting points and having a plurality of melting points instead of partially saponified EVOH has been proposed (for example, See Patent Document 2.). In the multilayer container, impact peeling resistance and transparency are maintained, and at the same time, gas barrier properties and thermal stability are improved.
[0004]
[Patent Document 1]
JP-A-11-348194
[Patent Document 2]
JP 2001-277341 A
[0005]
However, in a multilayer container which requires the use of partially saponified EVOH as described above, the impact peeling resistance may not satisfy the requirements depending on the bottle shape and application, so that a further improvement in the impact peeling resistance is required. Had been.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a resin composition which maintains characteristics such as gas barrier properties of EVOH and has excellent adhesiveness to a polyester resin. Another object of the present invention is to provide a multilayer container excellent in impact peeling resistance, containing a layer composed of the resin composition.
[0007]
[Means for Solving the Problems]
The above object is composed of an ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) having a polar group, and the weight ratio (A / B) of both is 50/50 to 99.8 / 0. .2 is achieved.
[0008]
In a preferred embodiment, the polar group contained in the thermoplastic resin (B) is at least selected from the group consisting of a carboxyl group, a boronic acid group, a boronic ester group, a boronic anhydride group and a boronic acid base. One functional group.
[0009]
In a preferred embodiment, the particles made of the thermoplastic resin (B) are dispersed in a matrix made of the EVOH (A).
[0010]
In a preferred embodiment, the EVOH (A) has an ethylene content of 20 to 60 mol% and a degree of saponification of 90 mol% or more.
[0011]
In a preferred embodiment, the present invention is a multilayer structure including at least one layer comprising the resin composition.
[0012]
In a preferred embodiment, the present invention is a multilayer container including at least one layer of the resin composition and at least one thermoplastic polyester layer.
[0013]
In a preferred embodiment, the multilayer container is formed by co-injection stretch blow molding.
[0014]
In a preferred embodiment, the multilayer container comprises only the layer composed of the resin composition and the thermoplastic polyester layer.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
EVOH (A) contained in the resin composition of the present invention is obtained by saponifying a copolymer of vinyl ester and ethylene using an alkali catalyst or the like. As the vinyl ester, vinyl acetate is mentioned as a typical compound, but other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can also be used.
[0016]
The EVOH (A) preferably has an ethylene content of 20 to 60 mol%. If the ethylene content is less than 20 mol%, the gas barrier properties under high humidity may decrease, and the melt moldability may further deteriorate. The ethylene content of EVOH is preferably at least 22 mol%, more preferably at least 24 mol%, and optimally at least 26 mol%. On the other hand, if the ethylene content exceeds 60 mol%, sufficient gas barrier properties may not be obtained. The ethylene content is preferably at most 55 mol%, more preferably at most 50 mol%.
[0017]
The saponification degree of the vinyl ester component of the EVOH (A) is preferably 90% or more, more preferably 95% or more, and still more preferably 96% or more. If the degree of saponification is less than 90 mol%, the gas barrier properties under high humidity may decrease. In addition, thermal stability becomes insufficient, and gels and bumps may be easily generated during molding.
[0018]
The EVOH (A) may be a mixture of two or more EVOHs having different ethylene contents and / or degrees of saponification. In this case, the average value calculated from the mixture weight ratio is defined as the ethylene content and the degree of saponification. And In this case, it is preferable that the difference in ethylene content between EVOHs having the most distant ethylene contents is 30 mol% or less, and the difference in the degree of caking is 10% or less. If these conditions are not satisfied, the transparency of the resin composition layer may be impaired. The difference in ethylene content is more preferably at most 20 mol%, even more preferably at most 15 mol%. Further, the difference in the degree of saponification is more preferably 7% or less, and still more preferably 5% or less. In the multilayer container containing the resin composition of the present invention, the ethylene content is 25 mol% or more and 55 mol% or less and the degree of saponification is increased for the purpose of balancing impact resistance and gas barrier properties at a higher level. An EVOH (a1) of 90% or more and less than 99% and an EVOH (a2) having an ethylene content of 25 mol% or more and 55 mol% or less and a degree of saponification of 99% or more are mixed at a blending weight ratio a1 / a2 of 5%. It is preferable to use a mixture such that the ratio becomes / 95 to 95/5.
[0019]
The ethylene content and the degree of saponification of EVOH can be determined by a nuclear magnetic resonance (NMR) method.
[0020]
This EVOH may also contain a small amount of a monomer other than ethylene and vinyl alcohol as a copolymer component as long as the object of the present invention is not hindered. Examples of such monomers include the following compounds: α-olefins such as propylene, 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene; itaconic acid, Unsaturated carboxylic acids such as methacrylic acid, acrylic acid and maleic acid, salts thereof, partial or complete esters thereof, nitriles thereof, amides thereof and anhydrides thereof; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy- Ethoxy) silanes, vinylsilane compounds such as γ-methacryloxypropyltrimethoxysilane; unsaturated sulfonic acids or salts thereof; alkylthiols; vinylpyrrolidones.
[0021]
Further, even when a boron compound is added to EVOH, the melt viscosity of EVOH is improved, and this is effective in that a homogeneous co-extrusion or co-injection molded product can be obtained. Here, examples of the boron compound include boric acids, borate esters, borates, and borohydrides. Specifically, examples of boric acids include orthoboric acid (hereinafter, may be abbreviated as boric acid), metaboric acid, tetraboric acid, and the like. Examples of borate esters include triethyl borate and trimethyl borate. Examples of the borate include alkali metal salts, alkaline earth metal salts, and borax of the above-mentioned various boric acids. Of these compounds, orthoboric acid is preferred.
[0022]
When a boron compound is added, its content is preferably from 20 to 2000 ppm, more preferably from 50 to 1000 ppm in terms of boron element. By being in this range, it is possible to obtain EVOH in which torque fluctuation during heating and melting is suppressed. If it is less than 20 ppm, the effect of adding the boron compound may be insufficient. On the other hand, if it exceeds 2000 ppm, gelation is likely to occur, resulting in poor moldability.
[0023]
It is also effective to add 5 to 5000 ppm of an alkali metal salt to EVOH, preferably in terms of an alkali metal element, for improving interlayer adhesion and compatibility. The addition amount of the alkali metal salt is more preferably 20 to 1000 ppm, more preferably 30 to 500 ppm in terms of an alkali metal element. Examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkali metal salt include an aliphatic carboxylate, an aromatic carboxylate, a phosphate, and a metal complex of the alkali metal. For example, sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and the like, among which sodium acetate, potassium acetate, and sodium phosphate are preferable. is there.
[0024]
It is also preferable to add a phosphate compound to EVOH at a ratio of preferably 20 to 500 ppm, more preferably 30 to 300 ppm, and most preferably 50 to 200 ppm in terms of phosphate groups. By blending the phosphoric acid compound in the above range, the thermal stability of EVOH can be improved. In particular, it is possible to suppress the occurrence and coloring of gel-like bumps when performing melt molding for a long time.
[0025]
The type of the phosphorus compound added to the EVOH is not particularly limited, and various acids such as phosphoric acid and phosphorous acid, salts thereof, and the like can be used. The phosphate may be in any form of a first phosphate, a second phosphate, or a third phosphate. The cationic species of the phosphate is not particularly limited, but the cationic species is preferably an alkali metal or an alkaline earth metal. Especially, it is preferable to add a phosphorus compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate.
[0026]
A suitable melt flow rate (MFR) of EVOH (at 190 ° C. under a load of 2160 g under JIS K7210) is 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, and even more preferably. 1 to 30 g / 10 min.
[0027]
The thermoplastic resin (B) having a polar group, which is contained in the resin composition of the present invention, has good compatibility with EVOH (A), which is a highly polar resin, by containing a polar group. And the obtained resin composition can form a stable morphology. At the same time, due to the presence of the thermoplastic resin (B), an improvement in impact peeling resistance is observed particularly in a multilayer container in which an adhesive resin is not used between PES and EVOH.
[0028]
The thermoplastic resin (B) is preferably a hydrocarbon polymer. Examples of the monomer forming the hydrocarbon polymer include the following compounds: α-olefins such as ethylene, propylene, 1-butene, isobutene, 3-methylpentene, 1-hexene and 1-octene. Styrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-tert-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, Styrenes such as-(phenylbutyl) styrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, tert-butoxystyrene; 1-vinylnaphthalene, 2-vinylnaphthalene Vinylnaphthalenes; indene, Vinylene group-containing aromatic compounds such as acenaphthylene; conjugated diene compounds such as butadiene, isoprene, 2,3-dimethylbutadiene, pentadiene and hexadiene; aromatic dicarboxylic acid compounds such as terephthalic acid and naphthalenedicarboxylic acid; ethylene glycol and trimethylene glycol And aliphatic diol compounds such as tetramethylene glycol. These monomers can be used alone or in combination of two or more.
[0029]
The following are examples of hydrocarbon-based polymers obtained using the above-mentioned monomers. Polyethylene (ultra low density, low density, linear low density, medium density, high density), ethylene- (meth) acrylate (methyl ester, ethyl ester, etc.) copolymer, ethylene-vinyl acetate copolymer, Olefin polymers such as ethylene-vinyl alcohol copolymer, polypropylene and ethylene-propylene copolymer; polystyrene, styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer, styrene-diene block copolymer ( Styrene-based polymers such as styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-isoprene-styrene block copolymer) and hydrogenated products thereof; polymethyl acrylate, polyethyl acrylate, polymethyl methacrylate (Meth) acrylic etc. Ester polymers; vinyl halide polymers such as polyvinyl chloride and vinylidene fluoride; semi-aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyvalerolactone, polycaprolactone, polyethylene succinate, polybutylene succinate, etc. Aliphatic polyesters; polyester elastomers and the like. In addition to the above-mentioned hydrocarbon polymers, polycarbonate, polyurethane, and the like can be used as the thermoplastic resin (B) having a polar group.
[0030]
The polar group contained in the thermoplastic resin (B) is not particularly limited, but is preferably a functional group containing an oxygen atom. Specifically, an active hydrogen-containing polar group (-SO ₃ H, -SO ₂ H, -SOH, -CONH ₂ , -CONHR, -CONH-, -OH, etc.) and a polar group containing nitrogen and containing no active hydrogen (-NCO, -OCN, -NO, -NO ₂ , -CONR ₂ , -CONR-, etc.), an epoxy group, a polar group containing a carbonyl group (-CHO, -COOH, -COOR, -COR,> C = O, -CSOR, -CSOH, etc.), a phosphorus-containing polar group (-P (OR ) ₂ , -PO (OR) ₂ , -PO (SR) ₂ , -PS (OR) ₂ , -PO (SR) (OR), -PS (SR) (OR), etc.), and a boron-containing polar group. (In the above formula, R represents an alkyl group, a phenyl group or an alkoxy group.)
[0031]
The method for producing the hydrocarbon polymer having a polar group is not particularly limited. For example, the following methods can be mentioned: 1) a method of copolymerizing the above monomer with a monomer containing a polar group (or a group capable of forming the polar group); 2) the above monomer A method of using an initiator or a chain transfer agent having the above-mentioned polar group (or a group capable of forming the above-mentioned polar group) when polymerizing; 3) living-polymerizing the above-mentioned monomer to produce the above-mentioned polar group (or A method of using a monomer having a group capable of forming the polar group) as a terminator (terminal treatment agent); and 4) polymerizing the monomer to obtain a polymer and reacting the polymer. A method of introducing a monomer having the polar group (or a group capable of forming the polar group) into an acidic moiety, for example, a carbon-carbon double bond moiety by a reaction. In the above method 1), when copolymerization is performed, any polymerization method such as random copolymerization, block copolymerization, or graft copolymerization can be employed.
[0032]
When the thermoplastic resin (B) having a polar group is a hydrocarbon polymer, particularly preferred polar groups include a carboxyl group and a boron-containing polar group (a boronic acid group, a boronic ester group, a boronic anhydride group). And boronic acid bases). Hereinafter, these polar groups and hydrocarbon-based polymers containing the polar groups will be sequentially described.
[0033]
In the present specification, the “carboxyl group” also includes a carboxylic anhydride group and a carboxylate group in addition to the carboxyl group. Among these, the carboxylate groups are those in which all or part of the carboxylic acid is present in the form of a metal salt. Examples of the metal of the metal salt include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, and transition metals such as zinc, manganese and cobalt. Among them, zinc is preferable from the viewpoint of compatibility.
[0034]
The method for preparing the carboxyl group-containing hydrocarbon polymer is not particularly limited, and the monomer exemplified above and the monomer containing a carboxyl group or a carboxylic anhydride group may be prepared by the method 1). Is preferably copolymerized. Among monomers used in such a method, examples of monomers having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, monomethyl maleate, monoethyl maleate, and itaconic acid. Among these, acrylic acid and methacrylic acid are preferred. The content of the carboxyl group in the polymer is preferably 0.5 to 20 mol%, more preferably 2 to 15 mol%, and still more preferably 3 to 12 mol%.
[0035]
Examples of the monomer having a carboxylic acid anhydride group include itaconic anhydride and maleic anhydride, and maleic anhydride is particularly preferable. The content of the carboxylic acid anhydride group in the polymer is preferably 0.0001 to 5 mol%, more preferably 0.0005 to 3 mol%, and still more preferably 0.001 to 1 mol%.
[0036]
The carboxylate group is introduced into the polymer by, for example, a salt exchange reaction between the polymer having a carboxyl group or a carboxylic anhydride group prepared by the above method and a low-molecular metal salt. The low-molecular metal salt at this time may contain one kind of the above-mentioned metals, or may contain two or more kinds of the above-mentioned metals.
[0037]
Examples of the metal counter ion in the low molecular weight metal salt include anions derived from organic acids or chlorides. Examples of the organic acid include acetic acid, stearic acid, dimethyldithiocarbamic acid, palmitic acid, 2-ethylhexanoic acid, neodecanoic acid, linoleic acid, tallic acid, oleic acid, resin acid, capric acid, and naphthenic acid. . Particularly preferred low molecular weight metal salts include cobalt 2-ethylhexanoate, cobalt neodecanoate, cobalt stearate and cobalt acetate.
[0038]
The degree of neutralization of the resulting carboxylic acid salt group is preferably less than 100%, more preferably 90% or less, and even more preferably 70% or less. It is preferably at least 5%, more preferably at least 10%, even more preferably at least 30%. For example, it is preferably 5 to 90%, more preferably 10 to 70%.
[0039]
The type of the hydrocarbon polymer containing a carboxyl group is not particularly limited, but as a monomer capable of forming a hydrocarbon polymer portion, an α-olefin is used, and the above-mentioned carboxyl group or carboxylic anhydride group is used. A copolymer obtained by copolymerization with a monomer having the same is preferable. Among them, a random copolymer is preferred from the viewpoint of the thermal stability of the obtained resin composition.
[0040]
Examples of the random copolymer include an ethylene-acrylic acid copolymer (EAA), an ethylene-methacrylic acid copolymer (EMAA), and metal salts thereof. Among these, EMAA and its metal salts are preferred.
[0041]
Further, a copolymer obtained by grafting a monomer having a carboxyl group or a carboxylic anhydride group to a polyolefin is also preferably used. As the polyolefin at this time, polyethylene (for example, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), etc.), polypropylene, copolymerized polypropylene And ethylene-vinyl acetate copolymer. As the monomer to be grafted, maleic anhydride is preferable.
[0042]
The carboxyl group-containing hydrocarbon polymer may contain the following monomers as copolymer components: vinyl esters such as vinyl acetate and vinyl propionate; methyl acrylate, ethyl acrylate Unsaturated carboxylic esters such as isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, isobutyl methacrylate and diethyl maleate; carbon monoxide and the like.
[0043]
The melt flow rate (MFR) of the polymer containing a carboxyl group (at 190 ° C. under a load of 2160 g) is usually 0.01 g / 10 min or more, preferably 0.05 g / min or more, more preferably Is 0.1 g / 10 min or more. Further, the MFR is usually 50 g / 10 minutes or less, preferably 30 g / 10 minutes or less, more preferably 10 g / 10 minutes or less.
[0044]
In the present specification, the “boron-containing polar group” specifically represents a boronic acid group, a boronic ester group, a boronic anhydride group, or a boronic acid base. The boronic acid group is represented by the following formula (I).
[0045]
Embedded image

[0046]
The boronic ester group, boronic anhydride group and boronic acid base are represented by the following formulas (II), (III) and (IV), respectively.
[0047]
Embedded image

[0048]
Embedded image

[0049]
Embedded image

[0050]
中 where X ₁ And X ₂ Are the same or different and are each a hydrogen atom, an aliphatic hydrocarbon group (such as a linear or branched alkyl group or alkenyl group having 1 to 20 carbon atoms), or an alicyclic hydrocarbon group (cycloalkyl group, cycloalkenyl group). Groups) and aromatic hydrocarbon groups (phenyl group, biphenyl group, etc.), wherein the aliphatic hydrocarbon group, alicyclic hydrocarbon group and aromatic hydrocarbon group have a substituent. And X ₁ And X ₂ May be bonded, provided that X ₁ And X ₂ Cannot be both hydrogen atoms. Also R ₁ , R ₂ And R ₃ Is the above X ₁ And X ₂ Represents a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group, and M represents an alkali metal. In the above formula, examples of the substituent which the aliphatic hydrocarbon group, alicyclic hydrocarbon group and aromatic hydrocarbon group may have include, for example, a carboxyl group, a halogen atom and the like. ｝
[0051]
Since the hydrocarbon-based polymer having a boron-containing polar group is very excellent in compatibility with EVOH, a multi-layer container comprising a layer made of a resin composition containing such a polymer and a PES layer is used. The transparency is not inferior to the transparency of the multilayer container composed of the EVOH layer and the PES layer. Furthermore, the former was found to be much better at impact delamination than the latter.
[0052]
Specific examples of the boronic ester group represented by the general formula (II) include the following groups: dimethyl boronate ester group, diethyl boronate group, dipropyl boronate group, diisopropyl boronate group, Boronic acid dibutyl ester group, boronic acid dihexyl ester group, boronic acid dicyclohexyl ester group, boronic acid ethylene glycol ester group, boronic acid propylene glycol ester group, boronic acid 1,3-propanediol ester group, boronic acid 1,3-butane Diol ester group, boronic acid neopentyl glycol ester group, boronic acid catechol ester group, boronic acid glycerin ester group, boronic acid trimethylolethane ester group and the like.
[0053]
Examples of the boronic acid group represented by the general formula (IV) include an alkali metal base of boronic acid. Specific examples include sodium boronate base and potassium boronate base.
[0054]
The content of the boron-containing polar group in the thermoplastic resin (B) having the boron-containing polar group is not particularly limited, but is preferably 0.0001 to 1 meq / g (milliequivalent / g), and 0.001 to 1 meq / g. 0.1 meq / g is more preferred.
[0055]
The method for producing the hydrocarbon polymer having a boron-containing polar group is not particularly limited, and any of the above methods 1) to 4) can be applied. Among them, representative examples of the methods 1), 2) and 4) are described below.
[0056]
By the method of the above 1) (a method of copolymerizing a monomer used for forming a hydrocarbon polymer and a monomer containing a polar group or a group capable of forming the polar group), By copolymerizing a monomer having a polar-containing group and a monomer capable of forming an olefin-based polymer, a vinyl-based polymer, a diene-based polymer, or the like, a hydrocarbon-based polymer having a boron-containing polar group is obtained. Coalescence is obtained. Examples of the monomer having a boron-containing polar group include, for example, 3-acryloylaminobenzeneboronic acid, ethylene glycol ester of 3-acryloylaminobenzeneboronic acid, 3-methacryloylaminobenzeneboronic acid, ethylene 3-methacryloylaminobenzeneboronic acid Glycol esters, 4-vinylphenylboronic acid, ethylene glycol esters of 4-vinylphenylboronic acid, and the like.
[0057]
The hydrocarbon-based polymer having a boron-containing polar group can also be prepared by the method of 2) above, using a thiol having a boron-containing polar group as a chain transfer agent, such as an olefin-based polymer, a vinyl-based polymer, or a diene-based polymer. It is obtained by radical polymerization of a monomer that can be formed. The resulting polymer has a boron-containing polar group at the terminal.
[0058]
The thiol having a boron-containing polar group (for example, a boronic acid group) can be obtained, for example, by reacting a thiol having a double bond with a diborane or a borane complex under a nitrogen atmosphere, and then adding an alcohol or water. . Examples of the thiol having a double bond as a raw material include 2-propen-1-thiol, 2-methyl-2-propen-1-thiol, 3-butene-1-thiol, and 4-pentene-1-thiol. Can be Among these, 2-propen-1-thiol and 2-methyl-2-propen-1-thiol are preferred. As the borane complex, a borane-tetrahydrofuran complex, a borane-dimethylsulfide complex, a borane-pyridine complex, a borane-trimethylamine complex, a borane-triethylamine complex, and the like are preferable. Among these, a borane-tetrahydrofuran complex and a borane-dimethylsulfide complex are preferable. The amount of diborane or borane complex to be added is preferably about the same as that of thiol having a double bond. The reaction temperature is preferably in the range from room temperature to 200 ° C. Examples of the solvent include ether solvents such as tetrahydrofuran (THF) and diglyme; and saturated hydrocarbon solvents such as hexane, heptane, ethylcyclohexane, and decalin. Of these, THF is preferred. As alcohols added after the reaction, lower alcohols such as methanol and ethanol are preferable, and methanol is more preferable.
[0059]
As the polymerization conditions for obtaining a polymer having a boron-containing polar group at the terminal, an azo-based or peroxide-based initiator is used, and the polymerization temperature is preferably in the range of room temperature to 150 ° C. The addition amount of the thiol having a boron-containing polar group is preferably about 0.001 to 1 mmol per 1 g of the monomer. The method for adding the thiol is not particularly limited, but when using a monomer that is easily chain-transferred such as vinyl acetate or styrene, it is preferable to add the thiol during polymerization, and it is preferable to add thiol during polymerization. In the case of using a compound that is difficult to undergo chain transfer, it is preferable to add thiol from the beginning.
[0060]
A monomer having the above polar group (boron-containing polar group) in a reactive portion of the polymer is obtained by polymerizing a monomer used for forming the hydrocarbon polymer of the above 4). The following two methods can be mentioned as a method for introducing a body by a reaction.
[0061]
Method 4-1): The above-mentioned hydrocarbon polymer having a boron-containing polar group is obtained by reacting a polymer having a carbon-carbon double bond with a borane complex and a trialkyl borate under a nitrogen atmosphere. By obtaining a thermoplastic resin having a boronic acid dialkyl ester group, and then reacting with water or an alcohol as required. In this method, a boron-containing polar group is introduced into the carbon-carbon double bond of the polymer having a carbon-carbon double bond by an addition reaction. In this production method, if a polymer having a double bond at a terminal is used as a raw material, a hydrocarbon polymer having a boron-containing polar group at a terminal can be obtained, and a double bond is provided as a raw material in a side chain or a main chain. If a polymer is used, a hydrocarbon polymer having a boron-containing polar group in a side chain can be obtained.
[0062]
Since an ordinary olefin polymer has a slight double bond at its terminal, it can be used as a raw material in the above-mentioned production method. Other methods for obtaining a polymer having a carbon-carbon double bond include a method of thermally decomposing an ordinary olefin-based polymer under oxygen-free conditions to obtain an olefin-based polymer having a double bond at a terminal, an olefin. And a method of obtaining a copolymer thereof using a monomer and a diene-based polymer as raw materials.
[0063]
Examples of the borane complex used in the above reaction include the borane complexes described in the above method 2). Among these, a borane-trimethylamine complex and a borane-triethylamine complex are more preferable. The amount of the borane complex charged is preferably in the range of 1/3 to 10 mol per 1 mol of the carbon-carbon double bond of the thermoplastic resin.
[0064]
As the boric acid trialkyl ester, a boric acid lower alkyl ester such as trimethyl borate, triethyl borate, tripropyl borate and tributyl borate is preferable. The amount of the trialkyl borate to be charged is preferably in the range of 1 to 100 mol per 1 mol of the carbon-carbon double bond of the thermoplastic resin. It is not necessary to use a solvent, but if used, a saturated hydrocarbon solvent such as hexane, heptane, octane, decane, dodecane, cyclohexane, ethylcyclohexane, and decalin is preferable.
[0065]
The reaction temperature is usually in the range of room temperature to 300 ° C., preferably 100 to 250 ° C., and the reaction is carried out at a temperature in this range for 1 minute to 10 hours, preferably 5 minutes to 5 hours.
[0066]
The boronic acid dialkyl ester group introduced into the thermoplastic resin by the above reaction can be prepared by a method generally used in the art, for example, water alone, a mixture of water and an organic solvent, or a 5% boric acid aqueous solution and an organic solvent. Can be converted into a boronic acid group by hydrolysis under a condition of room temperature to 150 ° C. for 10 minutes to 2 hours. Further, an arbitrary boronic ester group can be obtained by a transesterification reaction with alcohols by a usual method. Furthermore, it can be dehydrated and condensed by heating to form a boronic anhydride group. Further, it can be further reacted with a metal hydroxide or a metal alcoholate by a known method to obtain a boronate group.
[0067]
Examples of the organic solvent used for the conversion reaction of the boron-containing functional group include toluene, xylene, acetone, and ethyl acetate. Examples of alcohols include monoalcohols such as methanol, ethanol, and butanol; ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, neopentyl glycol, glycerin, trimethylolethane, pentaerythritol, And polyhydric alcohols such as pentaerythritol. Examples of the metal hydroxide include hydroxides of alkali metals such as sodium and potassium. Further, examples of the metal alcoholate include a metal alcoholate composed of the metal and the alcohol. These are not limited to those illustrated. The amount of these used is usually 1 to 100 mol per 1 mol of the boronic acid dialkyl ester group.
[0068]
Method 4-2): The hydrocarbon-based polymer having a boron-containing polar group may also be a carboxyl-containing polymer generally known in the art, m-aminophenylbenzeneboronic acid, m-aminophenyl It can be obtained by subjecting an amino group-containing boronic acid such as boronic acid ethylene glycol ester or an amino group-containing boronic ester to an amidation reaction by an ordinary method. During the reaction, a condensing agent such as carbodiimide may be used.
[0069]
Examples of the above-mentioned carboxyl group-containing thermoplastic resin include semi-aromatic polyester resin (PET or the like), aliphatic polyester resin, etc., and a polymer having a terminal carboxyl group, a polyolefin resin, a styrene-based resin, ) Acrylic acid ester resin, vinyl halide resin and other polymers are copolymerized with monomer units having carboxyl groups such as acrylic acid, methacrylic acid, itaconic acid, citraconic acid, fumaric acid and maleic anhydride. Examples include, but are not limited to, the introduced polymer and the above-mentioned thermoplastic resin containing an olefinic double bond, into which maleic anhydride or the like is introduced by an addition reaction.
[0070]
The melt flow rate (MFR) (230 ° C., load 2160 g) of the above-mentioned hydrocarbon polymer having a boron-containing polar group is preferably in the range of 0.1 to 100 g / 10 min, more preferably 0.1 to 100 g / 10 min. It is in the range of 2 to 50 g / 10 minutes.
[0071]
As described above, EVOH can also be used as the thermoplastic resin (B) having a polar group. Among them, an ethylene-vinyl alcohol copolymer having an ethylene content of 70 to 99 mol% and a saponification degree of 40% or more is preferable. The ethylene content is more preferably from 72 to 96 mol%, even more preferably from 72 to 94 mol%. When the ethylene content is less than 70 mol%, the impact peeling resistance of a multilayer container may not be sufficient. If the ethylene content exceeds 99 mol%, the compatibility with EVOH may be reduced. Further, the degree of saponification is more preferably at least 45%. The upper limit of the degree of saponification is not particularly limited, and those having a saponification degree of substantially 100% can be used. If the degree of saponification is less than 40%, the compatibility with EVOH may be reduced.
[0072]
The above EVOH has a melt flow rate (MFR) (190 ° C., load 2160 g) of preferably 0.1 g / 10 min or more, more preferably 0.5 g / 10 min or more. Further, it is preferably at most 100 g / 10 min, more preferably at most 50 g / 10 min, even more preferably at most 30 g / 10 min.
[0073]
The above-mentioned thermoplastic resin (B) having a polar group may be used alone or in combination of two or more.
[0074]
In the resin composition of the present invention, the weight ratio (A / B) of the EVOH (A) and the thermoplastic resin (B) having a polar group may be 50/50 to 99.8 / 0.2. is necessary. If the weight ratio is less than 50/50, the gas barrier properties against oxygen gas and carbon dioxide gas may be reduced. On the other hand, when the weight ratio exceeds 99.8 / 0.2, the content ratio of the thermoplastic resin (B) becomes small, so that sufficient impact peeling resistance may not be obtained. The weight ratio is preferably between 55/45 and 99/1, more preferably between 60/40 and 95/5, even more preferably between 70/30 and 90/10, and most preferably between 75/90 and 90/10. / 25 to 85/15.
[0075]
The resin composition of the present invention may contain a thermoplastic resin (C) other than the EVOH (A) and the thermoplastic resin (B) to the extent that the effects of the present invention are not impaired. The thermoplastic resin (C) is not particularly limited and includes, for example, the following compounds: polyethylene, polypropylene, ethylene-propylene copolymer, ethylene or propylene copolymer (ethylene or propylene and the following monomer Copolymer with at least one of the following: 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene and other α-olefins; vinyl formate, vinyl acetate, vinyl propionate, vinyl Carboxylic acid vinyl esters such as butyrate, vinyl octanoate, vinyl dodecanoate, vinyl stearate and vinyl arachidonate; vinyl silane compounds such as vinyl trimethoxy silane; vinyl pyrrolidones etc.), poly-4-methyl-1 Polyolefins such as pentene and poly 1-butene; polystyrene Poly acrylate, and the like.
[0076]
When selecting the thermoplastic resin (C) contained in the resin composition of the present invention, it is necessary to consider the miscibility of the thermoplastic resin (C) with the EVOH (A) and the thermoplastic resin (B). preferable. The miscibility of these resins may affect the resulting product's gas barrier properties, cleanliness, effectiveness as an oxygen scavenger, mechanical properties, product texture, and the like.
[0077]
The resin composition of the present invention may contain various additives as long as the effects of the present invention are not impaired. Examples of such additives include antioxidants, plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, ultraviolet absorbers, antistatic agents, lubricants, colorants, fillers, and desiccants. Fillers, pigments, dyes, processing aids, flame retardants, anti-fogging agents, and other high molecular compounds. Among the above, the heat stabilizer will be described below.
[0078]
Among the above additives, one or more of a hydrotalcite compound and a metal salt of a higher aliphatic carboxylic acid are used as the heat stabilizer. These compounds can prevent the generation of gels and fish eyes during the production of the resin composition, and can further improve long-term operation stability. These compounds are preferably contained at a ratio of 0.01 to 1% by weight of the whole resin composition.
[0079]
The metal salt of a higher aliphatic carboxylic acid is a metal salt of a higher fatty acid having 8 to 22 carbon atoms. Examples of the higher fatty acid having 8 to 22 carbon atoms include lauric acid, stearic acid, myristic acid and the like. Examples of the metal constituting the salt include sodium, potassium, magnesium, calcium, zinc, barium, aluminum and the like. Of these, alkaline earth metals such as magnesium, calcium and barium are preferred. Among such higher aliphatic carboxylic acid metal salts, calcium stearate and magnesium stearate are preferred.
[0080]
The resin composition of the present invention has a suitable melt flow rate (MFR) (190 ° C., under a load of 2160 g, based on JIS K7210) of 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min. And more preferably 1 to 30 g / 10 minutes. When the melt flow rate of the resin composition of the present invention is out of the above range, workability during melt molding often deteriorates.
[0081]
In the resin composition of the present invention, it is preferable that particles composed of the thermoplastic resin (B) are dispersed in a matrix composed of the EVOH (A). A molded article made of such a resin composition has good transparency, gas barrier properties, and impact resistance. At this time, the average particle size of the particles made of the thermoplastic resin (B) is preferably 10 μm or less. When the average particle size exceeds 10 μm, the area of the interface between the thermoplastic resin (B) and the matrix made of EVOH (A) becomes small, and the gas barrier property may be reduced. The average particle size of the thermoplastic resin (B) particles is more preferably 5 μm or less, and further preferably 2 μm or less.
[0082]
Each component of the resin composition of the present invention is mixed and processed into a desired product. The method of mixing the components of the resin composition of the present invention is not particularly limited, but a melt kneading method is preferred from the viewpoint of simplicity of the process and cost. At this time, using a device capable of achieving a high degree of kneading, and finely and uniformly dispersing each component, the gas barrier performance, transparency and impact peeling resistance are improved, and at the same time, the generation of gel, This is preferable because mixing can be prevented.
[0083]
Apparatuses with a high degree of kneading include continuous intensive mixers, kneading type twin-screw extruders (in the same direction or different directions), continuous kneading machines such as mixing rolls and co-kneaders, high-speed mixers, Banbury mixers, intensive mixers, A batch type kneader such as a kneader, an apparatus using a rotary disk having a grinding mechanism such as a stone mill such as a KCK kneading extruder manufactured by KCK, and a kneading unit (Dalmage, CTM, etc.) in a single screw extruder. Provided, a simple type kneader such as a ribbon blender or a Brabender mixer. Among these, a continuous kneader is preferred. Commercially available continuous intensive mixers include FCM manufactured by Farrel, CIM manufactured by Japan Steel Works, KCM, LCM, ACM manufactured by Kobe Steel Works, and the like. It is preferable to use a device in which a single screw extruder is installed below these kneaders and kneading and extrusion pelletizing are performed simultaneously. Examples of the twin-screw extruder having a kneading disk or a kneading rotor include TEX manufactured by Nippon Steel Works, ZSK manufactured by Werner & Pfleiderer, TEM manufactured by Toshiba Machine Co., Ltd., and PCM manufactured by Ikekai Iron Works Co., Ltd. Is mentioned.
[0084]
In these continuous kneaders, the shapes of the rotor and the disc play an important role. In particular, the gap (chip clearance) between the mixing chamber and the rotor chip or the disk chip is important, and a mixture with good dispersibility cannot be obtained if it is too narrow or too wide. The optimum chip clearance is 1 to 5 mm.
[0085]
The rotation speed of the rotor of the kneading machine is usually 100 to 1200 rpm, preferably 150 to 1000 rpm, and more preferably 200 to 800 rpm. The inner diameter (D) of the kneader chamber is usually 30 mm or more, preferably 50 to 400 mm. Further, the ratio L / D of the chamber length (L) to the inner diameter (D) of the kneader is preferably 4 to 30. One kneading machine may be used, or two or more kneading machines may be used in combination.
[0086]
The kneading temperature is usually in the range of 50 to 300 ° C. In order to prevent oxidation of the resin composition, it is preferable to extrude at a low temperature by sealing the hopper port with nitrogen. The kneading time is longer as long as a better result is obtained, but from the viewpoint of preventing the oxidation of the resin composition and the production efficiency, it is usually 10 to 600 seconds, preferably 15 to 200 seconds, more preferably 15 to 150 seconds. Seconds.
[0087]
The resin composition of the present invention can be formed into various molded products, for example, films, sheets, containers, and other packaging materials by appropriately employing a molding method. At this time, the resin composition of the present invention may be once formed into pellets and then subjected to molding, or each component of the resin composition may be dry-blended and directly subjected to molding.
[0088]
As a molding method and a molded product, for example, it can be molded into a film, sheet, pipe, or the like by melt extrusion molding, into a container shape by injection molding, or into a hollow container such as a bottle by hollow molding. Preferable examples of the hollow molding include extrusion hollow molding in which a parison is molded by extrusion molding and blow molding to form the same, and injection hollow molding in which a preform is molded by injection molding and blow molding is performed.
[0089]
In the present invention, the molded product obtained by the above molding may be a single layer, but from the viewpoint of imparting properties such as mechanical properties, water vapor barrier properties, and further oxygen barrier properties, it is laminated with another layer. It is preferable to use it as a multilayer structure.
[0090]
As the layer structure of the multilayer structure, x / y, if a layer made of a resin other than the resin composition of the present invention is an x layer, a resin composition layer of the present invention is a y layer, and an adhesive resin layer is a z layer, x / y / x, x / z / y, x / z / y / z / x, x / y / x / y / x, x / z / y / z / x / z / y / z / x, etc. However, the present invention is not limited to these. When a plurality of x layers are provided, the types may be the same or different. Further, a layer using a collected resin made of scrap such as trim generated during molding may be separately provided, or the collected resin may be blended with a layer made of another resin. Although the thickness configuration of each layer of the multilayer structure is not particularly limited, the thickness ratio of the y layer to the total layer thickness is preferably 2 to 20% from the viewpoint of moldability and cost.
[0091]
As the resin used for the x layer, a thermoplastic resin is preferable from the viewpoint of workability and the like. Such thermoplastic resins include, but are not limited to, the following resins: polyethylene, polypropylene, ethylene-propylene copolymers, ethylene or propylene copolymers (at least one of ethylene or propylene and the following monomers): Copolymer with 1 type: α-olefins such as 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene; non-copolymers such as itaconic acid, methacrylic acid, acrylic acid, and maleic anhydride Saturated carboxylic acid, its salt, its partial or complete ester, its nitrile, its amide, its anhydride; vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, vinyl dodecanoate, vinyl stearate Vinyl esters of carboxylic acids such as vinyl and arachidonate; vinyl Vinyl silane compounds such as limethoxysilane; unsaturated sulfonic acids or salts thereof; alkyl thiols; vinyl pyrrolidones etc.), polyolefins such as poly 4-methyl-1-pentene and poly 1-butene; polyethylene terephthalate, polybutylene terephthalate And polyesters such as polyethylene naphthalate; polyamides such as polyε-caprolactam, polyhexamethylene adipamide, and polymethaxylylene adipamide; polyvinylidene chloride, polyvinyl chloride, polystyrene, polyacrylonitrile, polycarbonate, polyacrylate and the like. Such a thermoplastic resin layer may be unstretched or may be uniaxially or biaxially stretched or rolled.
[0092]
Among these thermoplastic resins, polyolefins are preferred in terms of moisture resistance, mechanical properties, economy, heat sealing properties, and the like, and polyesters are preferred in terms of mechanical properties, heat resistance, and the like.
[0093]
On the other hand, the adhesive resin used for the z layer is not particularly limited as long as it can bond between the layers, and is a polyurethane- or polyester-based one-pack or two-pack curable adhesive, a carboxylic acid-modified polyolefin. Resins and the like are preferably used. The carboxylic acid-modified polyolefin resin is an olefin-based polymer or copolymer containing an unsaturated carboxylic acid or its anhydride (maleic anhydride or the like) as a copolymerization component; or an unsaturated carboxylic acid or its anhydride is an olefin-based polymer. Or a graft copolymer obtained by grafting the copolymer.
[0094]
Among these, a carboxylic acid-modified polyolefin resin is more preferable. In particular, when the x layer is a polyolefin resin, the adhesiveness with the y layer is improved. Examples of such carboxylic acid-modified polyolefin resins include polyethylene {low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE)}, polypropylene, copolymerized polypropylene, ethylene-vinyl acetate. Copolymers and ethylene- (meth) acrylate (methyl ester or ethyl ester) copolymers modified with carboxylic acid are exemplified.
[0095]
Examples of the method for obtaining the multilayer structure include an extrusion lamination method, a dry lamination method, a co-injection molding method, and a co-extrusion molding method, but are not particularly limited. Examples of the coextrusion molding method include a coextrusion laminating method, a coextrusion sheet molding method, a coextrusion inflation molding method, and a coextrusion blow molding method.
[0096]
The sheet, film, parison and the like of the multilayer structure thus obtained are reheated at a temperature equal to or lower than the melting point of the contained resin, and thermoforming methods such as drawing, roll stretching, pantograph stretching, Uniaxial or biaxial stretching by an inflation stretching method, a blow molding method, or the like can also be performed to obtain a stretched molded product.
[0097]
The transparency of the resin composition of the present invention is improved by selecting an appropriate resin. Therefore, by selecting a resin having good transparency as another resin to be laminated, a packaging container in which the contents are easily visible can be obtained. From such a viewpoint, the haze value of the multilayer structure having the resin composition layer of the present invention is preferably 10% or less, more preferably 5% or less, and still more preferably 3% or less.
[0098]
Molded articles using the above multilayer structure are used for various applications. In particular, the effect of the multilayer structure of the present invention is greatly exhibited when the multilayer container is used. Among such packaging containers, the following two aspects are cited as aspects in which the performance required for transparency is strict and the utility of using the resin composition of the present invention is great. That is, one is a container comprising a multilayer film having a total layer thickness of not more than 300 μm including a layer composed of the resin composition of the present invention, and the other is a layer composed of the resin composition of the present invention and a PES layer Are multilayer containers containing at least one layer each. Hereinafter, these embodiments will be sequentially described.
[0099]
A container comprising a multilayer film having a total thickness of 300 μm or less, including a layer composed of the resin composition of the present invention, is a flexible container having a multilayer structure having a relatively small overall layer thickness, and is usually in the form of a pouch or the like. Has been processed. Since this container has excellent gas barrier properties and is easy to manufacture, it is extremely useful for packaging products that are sensitive to oxygen and easily deteriorate.
[0100]
Generally, as a container requiring good transparency, a container having a small thickness as a whole, in which the thickness of each resin layer constituting the multilayer structure is small, is manufactured. For example, when using a crystalline resin such as polyolefin, if the thickness is large, the transparency is often deteriorated due to scattering by crystals, whereas if the container is thin, it is good. Transparency is obtained. In general, even if a resin that is crystallized without stretching has poor transparency, a resin that is crystallized by stretching and orientation has good transparency. Such a uniaxially or biaxially stretched film is usually thin, and from this point of view, a thin multilayer structure often provides good transparency.
[0101]
The transparency of the resin composition of the present invention is improved by selecting an appropriate resin. Therefore, it can be suitably used for a container made of a thin multilayer film, which often requires transparency. Even if the transparency of such a thin film deteriorates with time, the degree is small. The thickness of such a multilayer film is not particularly limited, but is preferably 300 μm or less, more preferably 250 μm or less, and still more preferably 200 μm or less from the viewpoint of maintaining transparency and flexibility. . On the other hand, considering the mechanical properties of the container, the total layer thickness is preferably at least 10 μm, more preferably at least 20 μm, and even more preferably at least 30 μm.
[0102]
When the above-mentioned multilayer container is manufactured from a multilayer film, the method for manufacturing the multilayer film is not particularly limited. For example, the resin composition layer of the present invention and another thermoplastic resin layer may be dry-laminated, co-extruded laminating, or the like. A multilayer film can be obtained by laminating by a method.
[0103]
In the case of dry lamination, non-stretched films, uniaxially stretched films, biaxially stretched films, rolled films, and the like can be used. Among these, a biaxially stretched polypropylene film, a biaxially stretched polyethylene terephthalate film, and a biaxially stretched poly ε-caprolactam film are preferred from the viewpoint of mechanical strength, and in view of moisture resistance, a biaxially stretched polypropylene film is particularly preferred. When a non-stretched film or a uniaxially stretched film is used, the multilayer film is reheated after lamination, and is uniaxially or biaxially stretched by a thermoforming method such as drawing, a roll stretching method, a pantograph stretching method, an inflation stretching method, or the like. Thereby, a stretched multilayer film can be obtained.
[0104]
In order to seal the obtained multilayer container, it is also preferable to provide a layer made of a heat-sealable resin on at least one outermost layer surface during the production of the multilayer film. Examples of such a resin include polyolefins such as polyethylene and polypropylene.
[0105]
The multilayer film thus obtained is processed into a bag shape, for example, and can be used as a packaging container for filling the contents. Since it is flexible, simple, and excellent in transparency, it is extremely useful for packaging of contents that are easily degraded by the presence of oxygen, particularly foods and the like.
[0106]
The multilayer container including at least one layer each composed of the resin composition of the present invention and the PES layer has excellent gas barrier properties, and the transparency is improved by selecting an appropriate resin. Therefore, it is used in various forms such as a bag-shaped container, a cup-shaped container, and a hollow molded container. Among these, hollow molded containers, especially bottles, are important.
[0107]
Bottles made of PES are now widely used as beverage containers. In such applications, it is necessary to prevent deterioration of the contents, and it is required that the beverage as the contents be sufficiently visible to the consumer. In addition, when filling contents such as beer that is extremely susceptible to flavor deterioration due to oxygen, it is desired to have an extremely high gas barrier property.
[0108]
The multilayer container including at least one layer each composed of the resin composition layer and the PES layer of the present invention can obtain high transparency and has extremely excellent content quality retention performance. Optimal. As the layer configuration of the multilayer container, an adhesive resin layer may be disposed between the resin composition layer and the PES layer, but the PES layer is disposed so as to directly contact both surfaces of the resin composition layer. The multilayer container is particularly preferable from the viewpoint that higher transparency can be obtained and the effect of the present invention such as excellent impact separation resistance between the resin composition layer and the PES layer can be sufficiently exhibited.
[0109]
As the PES used in the multilayer container of the present invention composed of the layer composed of the resin composition of the present invention and the PES layer, a condensation polymer containing an aromatic dicarboxylic acid or an alkyl ester thereof and a diol as main components is used. Can be In particular, to achieve the object of the present invention, PES mainly containing an ethylene terephthalate component is preferable. Specifically, the total ratio (mol%) of terephthalic acid units and ethylene glycol units is preferably 70 mol% or more, and more preferably 90 mol%, based on the total mol number of all structural units constituting PES. The above is more preferable. If the total proportion of terephthalic acid units and ethylene glycol units is less than 70 mol%, the resulting PES will be amorphous, will have insufficient mechanical strength, and will be filled with heat after stretching to form a container ( When hot-filling is performed, heat shrinkage is so large that it may not endure use. In addition, when solid-phase polymerization is performed to reduce the amount of oligomers contained in the resin, sticking due to softening of the resin is likely to occur, and production may be difficult.
[0110]
The PES may contain a bifunctional compound unit other than a terephthalic acid unit and an ethylene glycol unit as needed, as long as the above problem does not occur. The ratio (mol%) is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, based on the total mol number of all structural units constituting PES. Examples of such a bifunctional compound unit include a dicarboxylic acid unit, a diol unit, and a hydroxycarboxylic acid unit, and may be any of aliphatic, alicyclic, and aromatic. Specific examples include a neopentyl glycol unit, a cyclohexane dimethanol unit, a cyclohexane dicarboxylic acid unit, an isophthalic acid unit, and a naphthalenedicarboxylic acid unit.
[0111]
Among these, the isophthalic acid unit has the advantage that when the obtained PES is used, the production conditions under which a good molded product can be obtained are wide and the moldability is excellent, so that the reject rate is low. It is also preferable from the viewpoint that whitening of a molded article can be prevented by suppressing the crystallization rate. Further, a 1,4-cyclohexanedimethanol unit or a 1,4-cyclohexanedicarboxylic acid unit is preferable in that the obtained molded product has more excellent strength when dropped. Further, the naphthalenedicarboxylic acid unit is preferable because the glass transition temperature of the obtained PES is increased, and the heat resistance is improved and the ability to absorb ultraviolet rays is provided. Especially useful. For example, it is particularly useful when the contents are easily degraded by oxidation or ultraviolet light, such as beer.
[0112]
When a polycondensation catalyst is used in the production of PES, a catalyst usually used in the production of PES can be used. For example, antimony compounds such as antimony trioxide; germanium compounds such as germanium dioxide, germanium tetraethoxide, and germanium tetra-n-butoxide; tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetratetratitanium Titanium compounds such as butoxytitanium; tin compounds such as di-n-butyltin dilaurate, di-n-butyltin oxide and dibutyltin diacetate can be used. These catalysts may be used alone or in combination of two or more. The amount of the polycondensation catalyst used is preferably in the range of 0.002 to 0.8% by weight based on the weight of the dicarboxylic acid component.
[0113]
Of these, antimony compounds are preferred from the viewpoint of catalyst cost, and antimony trioxide is particularly preferred. On the other hand, a germanium compound is preferable, and germanium dioxide is particularly preferable, from the viewpoint that the color tone of the obtained PES is good. From the viewpoint of moldability, a germanium compound is more preferable than an antimony compound. PES obtained by a polymerization reaction using an antimony compound as a catalyst has a higher crystallization rate than PES polymerized using a germanium compound as a catalyst, and crystallization by heating easily proceeds during injection molding or blow molding. The whitened bottle may be whitened and the transparency may be impaired. In addition, the draw orientation may decrease, and the shapeability may deteriorate. As described above, the range of manufacturing conditions under which a good molded product can be obtained is narrowed, and the defective product ratio tends to increase.
[0114]
In particular, when polyethylene terephthalate that does not contain a copolymer component other than the by-produced diethylene glycol unit is used as the PES used in the present invention, when producing the PES, a germanium compound is used to suppress the crystallization rate. Is preferably used as a catalyst.
[0115]
The method for producing the multilayer container of the present invention, which includes at least one layer composed of the resin composition and at least one PES layer, is not particularly limited, but it is preferable to use co-injection blow molding from the viewpoint of productivity and the like. It is. In co-injection blow molding, a container is manufactured by stretch blow-molding a container precursor (parison) obtained by co-injection molding.
[0116]
In co-injection molding, the resin that constitutes each layer of the multilayer structure is usually guided into concentric nozzles from two or more injection cylinders, and simultaneously or alternately at a different timing, to form a single mold. And molding is performed by performing a single mold clamping operation. For example, (1) a method of injecting a PES layer for the inner and outer layers first, and then injecting a resin composition to be an intermediate layer to obtain a molded container having a three-layer structure of PES / resin composition / PES, (2) 5) PES layers for the inner and outer layers are first injected, then the resin composition is injected, and simultaneously or after that, the PES layer is injected again, resulting in five layers of PES / resin composition / PES / resin composition / PES. The parison is manufactured by a method of obtaining a molded container having the above configuration, but the method is not limited to these methods. In the above-described layer configuration, an adhesive resin layer may be provided between the resin composition layer and the PES layer, if necessary.
[0117]
As the conditions for injection molding, PES is preferably injected in a temperature range of 250 to 330C, more preferably 270 to 320C, and even more preferably 280 to 310C. When the injection temperature of PES is lower than 250 ° C., PES is not sufficiently melted, and unmelted material (fish eye) is mixed in the molded product to cause poor appearance, and at the same time, the cause of the decrease in mechanical strength of the molded product. There is a risk of becoming. Further, in an extreme case, the screw torque increases, which may cause a failure of the molding machine. On the other hand, when the injection temperature of PES exceeds 330 ° C., the decomposition of PES becomes remarkable, and there is a possibility that the mechanical strength of the molded product may be reduced due to a decrease in molecular weight. Further, not only the property of the substance to be filled into the molded product is impaired by the gas such as acetaldehyde generated during decomposition, but also the oligomer generated during the decomposition may cause severe contamination of the mold, which may impair the appearance of the molded product.
[0118]
The resin composition is preferably injected in a temperature range of 170 to 250 ° C, more preferably 180 to 240 ° C, even more preferably 190 to 230 ° C. When the injection temperature of the resin composition is lower than 170 ° C., the resin composition is not sufficiently melted, and an unmelted material (fish eye) may be mixed into the molded product, resulting in poor appearance. Further, in an extreme case, the screw torque increases, which may cause a failure of the molding machine. On the other hand, when the injection temperature of the resin composition exceeds 250 ° C., oxidation of the thermoplastic resin (B) proceeds, and the gas barrier properties and the oxygen scavenging function of the resin composition may be reduced. At the same time, the appearance of the molded article may be poor due to coloring or gelling, or the fluidity may be non-uniform or impaired by the decomposition gas or gelling, resulting in a missing portion of the resin composition layer. In an extreme case, injection molding becomes impossible due to generation of a gel. In order to suppress the progress of oxidation during melting, it is also preferable to seal the raw material supply hopper with nitrogen.
[0119]
The resin composition may be supplied to the molding machine in the form of pellets in which the raw material components have been melt-blended in advance, or each of the dry-blended raw material components may be supplied to the molding machine.
[0120]
The temperature of the hot runner portion into which PES and the resin composition flow is preferably in the range of 220 to 300C, more preferably 240 to 280C, and even more preferably 250 to 270C. When the temperature of the hot runner portion is lower than 220 ° C., PES is crystallized and solidified in the hot runner portion, so that molding may be difficult. On the other hand, when the temperature of the hot runner portion exceeds 300 ° C., the oxidation of the resin composition proceeds, the appearance of the molded product becomes poor due to coloring or gelling, or the fluidity becomes non-uniform due to decomposition gas or gelling or In some cases, it may be hindered, resulting in a missing portion of the resin composition layer. In an extreme case, injection molding becomes impossible due to generation of a gel.
[0121]
The mold temperature is preferably in the range of 0 to 70C, more preferably 5 to 50C, and even more preferably 10 to 30C. Thereby, the crystallization of the parison PES and the resin composition is suppressed, uniform stretchability is secured, the delamination resistance and transparency of the obtained multilayer container are improved, and a molded product having a stable shape is obtained. be able to. If the mold temperature is less than 0 ° C., the appearance of the parison may be impaired due to condensation of the mold, and a good molded product may not be obtained. When the mold temperature exceeds 70 ° C., the crystallization of the PES of the parison and the resin composition is not suppressed, the stretchability becomes non-uniform, and the delamination resistance and the transparency of the obtained molded product are reduced. However, it is difficult to obtain a molded product having an intended shape.
[0122]
In the parison thus obtained, the total thickness is preferably 2 to 5 mm, and the total thickness of the resin composition layer is preferably 10 to 500 µm.
[0123]
The parison is sent to a stretching blow step directly after being heated at a high temperature or after being reheated using a heating element such as a block heater or an infrared heater. The multi-layer injection blow-molded container of the present invention is manufactured by stretching the heated parison 1 to 5 times in the longitudinal direction in the stretch blow step, and then performing stretch blow molding 1 to 4 times with compressed air or the like. Can be. The temperature of the parison is preferably from 75 to 150 ° C, more preferably from 85 to 140 ° C, even more preferably from 90 to 130 ° C, and most preferably from 95 to 120 ° C. If the temperature of the parison exceeds 150 ° C., the PES tends to crystallize, and the resulting container may be whitened to impair the appearance or increase delamination of the container. On the other hand, if the temperature of the parison is lower than 75 ° C., crazes may occur in the PES, resulting in a pearly tone and impairing transparency.
[0124]
The total thickness of the body part of the multilayer container thus obtained is generally 100 to 2000 μm, preferably 150 to 1000 μm, and can be properly used depending on the application. At this time, the total thickness of the resin composition layer is preferably in the range of 2 to 200 μm, more preferably 5 to 100 μm.
[0125]
Thus, a multilayer container comprising the layer composed of the resin composition of the present invention and the PES layer is obtained. This container can obtain high transparency, and is extremely excellent in gas barrier properties and impact peeling resistance. Therefore, it is useful as a container for contents that are susceptible to deterioration due to the presence of oxygen, such as foods and pharmaceuticals. In particular, it is extremely useful as a container for beverages such as beer.
[0126]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0127]
As the EVOH (A), those having the composition and physical properties shown in Table 1 were used. However, EVOH2 was produced as follows.
[0128]
(Manufacture of EVOH2)
80 parts by weight of EVOH having an ethylene content of 32 mol% and a saponification degree of 99.5 mol%, and 20 parts by weight of EVOH having an ethylene content of 44 mol% and a saponification degree of 96.5 mol% were dry-blended. Next, using a 30 mmφ twin screw extruder (Nippon Steel Works TEX-30SS-30CRW-2V), the extruder temperature was 210 ° C. (resin temperature 220 ° C.), the screw rotation speed was 300 rpm, and the extruded resin amount was 25 kg / It was extruded under the condition of time and pelletized. Finally, drying was performed at 80 ° C. for 16 hours under dehumidified air to obtain EVOH2.
[0129]
[Table 1]

[0130]
Those shown in Table 2 were used as the thermoplastic resin (B) having a functional group. However, B-1 was manufactured as follows.
[0131]
Styrene-hydrogenated butadiene-styrene triblock copolymer B-3 (weight average molecular weight 100400, styrene / hydrogenated butadiene = 18/82 (weight ratio), 1,2-bond / 1,4-bond mol of butadiene unit) Ratio = 47/53, hydrogenation rate of butadiene unit 97%, double bond amount 430 μeq / g, melt index 5 g / 10 min (230 ° C., 2160 g load), density 0.89 g / cm ³ ) Was supplied to a twin-screw extruder at a rate of 7 kg / hour while replacing the inlet with nitrogen at 1 L / min. Next, a liquid mixture (TEAB / BBD = 29/71, weight ratio) of borane-triethylamine complex (TEAB) and 1,3-butanediol borate (BBD) was fed from the liquid feeder 1 at a rate of 0.6 kg / hour. Then, 1,3-butanediol was supplied from the liquid feeder 2 at a rate of 0.4 kg / hour, and was continuously kneaded. During kneading, the pressure was adjusted so that the gauges of vent 1 and vent 2 indicated about 20 mmHg. As a result, a triblock copolymer (B-1) containing a 1,3-butanediol boronic acid ester group (BBDE) was obtained at a rate of 7 kg / hour from the discharge port. The boronic acid 1,3-butanediol ester group content of B-1 was 210 μeq / g.
[0132]
The configuration and operating conditions of the twin-screw extruder used for the reaction are as follows.

[0133]
[Table 2]

[0134]
Example 1
EVOH1 shown in Table 1 was used as A, and B-1 shown in Table 2 was used as B. 80 parts by weight of EVOH1 and 20 parts by weight of B-1 were dry blended, and a 30 mmφ twin screw extruder (TEX-30SS-30CRW-2V manufactured by Nippon Steel Works Co., Ltd.) was used. The resin composition was extruded and pelletized under conditions of several 300 rpm and an extruded resin amount of 25 kg / hour, and dried at 80 ° C. for 16 hours under dehumidified air to obtain resin composition pellets. The melt flow rate (at 190 ° C., 2160 g load) of this resin composition was 1.6 g / 10 minutes. Observation of the fracture surface of the resin composition pellet with an electron microscope revealed that particles of B-1 having a size of about 1 μm or less were dispersed in a matrix composed of EVOH1. Table 3 shows the results.
[0135]
In producing the multilayer container, polyethylene terephthalate (PET) obtained by polymerization using germanium dioxide as a catalyst was used as the thermoplastic polyester. The contents of terephthalic acid units, ethylene glycol units, and diethylene glycol units in the PET were 50.0 mol%, 48.9 mol%, and 1.1 mol%, respectively. The intrinsic viscosity was 0.83 dl / g, the melting point and the glass transition temperature were 252 ° C. and 80 ° C., respectively.
[0136]
Next, using the above-mentioned resin composition pellets and the above-mentioned PET as raw materials, the weight ratio of the PET layer and the resin composition layer in the multilayer container was set to 95 using a KORTEC / HUSKY co-injection molding machine (SL160 type four-cavity). The injection speed and the injection amount were adjusted so that the ratio became / 5, and co-injection molding was performed to produce a bottomed parison of two types and three layers of PET / resin composition / PET. At this time, the temperature of the PET-side injection machine was 280 ° C., the temperature of the resin composition-side injection machine was 210 ° C., the temperature of the hot runner block where the PET and the resin composition merged was 270 ° C., and the core temperature of the injection mold. Was 10 ° C., and the cavity temperature of the injection mold was 10 ° C.
[0137]
Thereafter, the surface temperature of the bottomed parison was heated to 105 ° C. using a CRUPP CORPOPLAST MASCHINENBAU stretch blow molding machine (LB01 type, 530 mL, one-piece), stretch blow-molded, and a 2-type, 3-layer multilayer container was obtained. Obtained. The obtained multilayer container was cut at the trunk, and the thickness of each layer was measured. As a result, the inner layer PET was 140 μm, the intermediate layer resin composition was 30 μm, and the outer layer PET was 190 μm. The impact peeling rate, haze value, and oxygen permeation rate of this multilayer container were measured as follows.
[0138]
Impact peeling rate: After filling the container with water and sealing it under normal pressure, the corner of the container is placed on a 20 cm long triangular table with a 90 ° angle from a height of 60 cm. The container was allowed to fall naturally only once with the container body leveled so as to hit the center of the container. The test was performed on 100 containers, and the delamination occurrence rate (Rd) was calculated from the number (Nd) of the containers having peeled off using the following equation.
Rd (%) = (Nd / 100) × 100
[0139]
Haze value: For the four locations obtained by dividing the center of the container body into four parts on the circumference, use a Poick integrating sphere light transmittance / total light reflectance meter (“HR-100” manufactured by Murakami Color Research Laboratory). The internal haze value was measured according to ASTM D1003-61, and the average value was taken as the haze value of the container.
[0140]
Oxygen Permeation Rate: After adjusting the temperature and humidity of the outside of the container to 20 ° C.-65% RH and the inside of the container to 20 ° C.-100% RH while keeping the shape of the container, an oxygen permeation speed measuring device (OX- manufactured by Modern Control Co., Ltd. TRAN-10 / 50A) was used to measure the oxygen permeation rate (ml / (container.day.atm)) per container. Table 4 summarizes the above results.
[0141]
Example 2
A resin composition pellet was obtained in the same manner as in Example 1 except that EVOH2 was used instead of EVOH1 as A. The melt flow rate of this resin composition (190 ° C., 2160 g load) was 1.7 g / 10 minutes. Observation of the fracture surface of the resin composition pellet by an electron microscope revealed that particles of B-1 having a size of about 1 μm or less were dispersed in a matrix composed of EVOH2. Table 3 shows the results.
Thereafter, co-injection stretch blow molding was carried out in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value and oxygen permeation rate were measured. Table 4 shows the results.
[0142]
Example 3
As B, a resin composition pellet was obtained in the same manner as in Example 1 except that maleic anhydride-modified polyethylene (B-2, “Admer” SF-700 manufactured by Mitsui Chemicals, Inc.) was used instead of B-1. Was. The melt flow rate (at 190 ° C., 2160 g load) of this resin composition was 1.2 g / 10 minutes. Observation of the fracture surface of the resin composition pellet by an electron microscope revealed that particles of B-2 having a size of approximately 1 μm or less were dispersed in a matrix composed of EVOH1. Table 3 shows the results.
Thereafter, co-injection stretch blow molding was carried out in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value and oxygen permeation rate were measured. Table 4 shows the results.
[0143]
Example 4
A resin composition pellet was obtained in the same manner as in Example 2, except that B-2 was used instead of B-1 as B. The melt flow rate (at 190 ° C., 2160 g load) of this resin composition was 1.2 g / 10 minutes. Observation of the fracture surface of the resin composition pellet by an electron microscope revealed that particles of B-2 having a size of about 1 μm or less were dispersed in a matrix composed of EVOH2. Table 3 shows the results.
Thereafter, co-injection stretch blow molding was carried out in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value and oxygen permeation rate were measured. Table 4 shows the results.
[0144]
Comparative Example 1
EVOH1 was used in place of the resin composition (Table 3). Co-injection stretch blow molding was performed in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value, and oxygen transmission rate were measured. Table 4 shows the results.
[0145]
Comparative Example 2
EVOH2 was used in place of the resin composition (Table 3). Co-injection stretch blow molding was performed in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value, and oxygen transmission rate were measured. Table 4 shows the results.
[0146]
Comparative Example 3
30 parts by weight of EVOH2 and 70 parts by weight of B-1 were dry-blended to obtain resin composition pellets in the same manner as in Example 1. The melt flow rate (190 ° C., 2160 g load) of this resin composition was 5.8 g / 10 minutes. Observation of the fracture surface of the resin composition pellet by an electron microscope revealed that particles of EVOH2 having a size of about 1 μm or less were dispersed in the matrix composed of B-1. Table 3 shows the results.
Thereafter, the production of a multilayer container was attempted in the same manner as in Example 1. However, the obtained resin composition pellets had extremely high tackiness, and even when a lubricant was added, stable supply to an injection molding machine was difficult. Therefore, it was judged that it was not practical, and other evaluations were stopped.
[0147]
Comparative Example 4
A resin composition pellet was obtained in the same manner as in Example 2 except that B-3 was used as a raw material of B-1 instead of B-1. The melt flow rate (at 190 ° C., under a load of 2160 g) of this resin composition was 1.8 g / 10 minutes. Observation of the fracture surface of the resin composition pellet by an electron microscope revealed that particles of B-3 having a particle size of about 5 μm or less were dispersed in a matrix composed of EVOH2. Table 3 shows the results.
Thereafter, co-injection stretch blow molding was carried out in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value and oxygen permeation rate were measured. Table 4 shows the results.
[0148]
Comparative Example 5
As B, a resin composition pellet was obtained in the same manner as in Example 2, except that a linear low-density polyethylene (B-4, “Ultzex” 3021F manufactured by Mitsui Chemicals, Inc.) was used instead of B-1. Was. The melt flow rate of this resin composition (190 ° C., 2160 g load) was 2.1 g / 10 minutes. Observation of the fracture surface of the resin composition pellet by an electron microscope revealed that particles of about 10 μm or less of B-4 were dispersed in a matrix composed of EVOH1. Table 3 shows the results.
Thereafter, co-injection stretch blow molding was carried out in the same manner as in Example 1 to obtain a multilayer container of two kinds and three layers, and the impact peeling occurrence rate, haze value and oxygen permeation rate were measured. Table 4 shows the results.
[0149]
[Table 3]

[0150]
[Table 4]

[0151]
【The invention's effect】
The resin composition of the present invention maintains characteristics such as gas barrier properties of EVOH, and is excellent in adhesiveness to a polyester resin, so a multilayer structure composed of the resin composition and the polyester resin, The co-injection stretch blow-molded multilayer container is excellent in impact peeling resistance.

Claims (8)

A resin comprising an ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) having a polar group, and having a weight ratio (A / B) of 50/50 to 99.8 / 0.2. Composition. The polar group contained in the thermoplastic resin (B) is at least one functional group selected from the group consisting of a carboxyl group, a boronic acid group, a boronic ester group, a boronic anhydride group, and a boronic acid base. The resin composition according to claim 1. 3. The resin composition according to claim 1, wherein the particles composed of the thermoplastic resin (B) are dispersed in a matrix composed of the ethylene-vinyl alcohol copolymer (A). 4. The resin composition according to any one of claims 1 to 3, wherein the ethylene-vinyl alcohol copolymer (A) has an ethylene content of 20 to 60 mol% and a degree of saponification of 90 mol% or more. A multilayer structure comprising at least one layer comprising the resin composition according to claim 1. A multilayer container comprising at least one layer each comprising the resin composition according to any one of claims 1 to 4 and a thermoplastic polyester layer. The multilayer container according to claim 6, which is formed by coinjection stretch blow molding. The multilayer container according to claim 6, which comprises only a layer made of the resin composition and the thermoplastic polyester layer.