JP4195326B2 - Air-cooled inflation molded multilayer film - Google Patents

Description

【００３３】
（式中、Ｒ^１は水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^２およびＲ^３はそれぞれ水素原子、炭素数１〜１２のアルキル基、シクロアルキル基、アリール基又はアラルキル基を示す。Ｍはアルカリ金属、アルカリ土類金属、アルミニウム、亜鉛のいずれかを示し、Ｍがアルカリ金属のときｍは０を、ｎは１を示し、Ｍが二価金属のときｎは１又は２を示し、ｎが１のときｍは１を、ｎが２のときｍは０を示し、Ｍがアルミニウムのときｍは１を、ｎは２を示す。）
【００３４】
安息香酸金属塩を含む樹脂を用いて成形されたフィルムは、特に経済性に優れ安価であるため汎用の包装向けに好適である。安息香酸金属塩の具体例としては、ヒドロキシ−ジ（ｔ−ブチル安息香酸）アルミニウム等が挙げられる。
【００３５】
高密度ポリエチレンを含む樹脂を用いて成形されたフィルムは、特に加工安定性に優れるため、高速成形性に優れ、あらゆる包装フィルム用途に好適である。高密度ポリエチレンとして好ましいものは、下記（Ｃ１）、（Ｃ２）の特性を有する高密度ポリエチレン（Ｃ）成分である。
【００３６】
（Ｃ１）メルトフローレート（ＭＦＲ：１９０℃、２１．１８Ｎ荷重）
本発明で用いる高密度ポリエチレンのＭＦＲ（１９０℃、２１．１８Ｎ荷重）は、１０ｇ／１０分以上、好ましくは１０〜３０００ｇ／１０分である。高密度ポリエチレンのＭＦＲが１０ｇ／１０分未満であると、ポリエチレンの分散径が充分に小さくならず、フィルム表面に分散粒子が凹凸として反映されてしまうため透明性の悪化につながる。また、ポリエチレンが微分散するためには、好ましくは高密度ポリエチレンのメルトフローレートがプロピレン・α−オレフィン共重合体のメルトフローレートより大きい方がよい。
なお、高密度ポリエチレンのＭＦＲは、ＪＩＳ−Ｋ６９２２−２：１９９７付属書（１９０℃、２１．１８Ｎ荷重）に準拠して測定する。
【００３７】
（Ｃ２）密度
本発明で用いる高密度ポリエチレンの密度は、０．９４〜０．９８ｇ／ｃｍ^３、好ましくは０．９５〜０．９８ｇ／ｃｍ^３、さらに好ましくは０．９６〜０．９８ｇ／ｃｍ^３である。高密度ポリエチレンの密度が０．９４ｇ／ｃｍ^３未満では、透明性改良効果が充分ではなく、０．９８ｇ／ｃｍ^３を超えるポリエチレンの製造は困難である。
なお、高密度ポリエチレンの密度は、ＪＩＳ−Ｋ６９２２−２：１９９７付属書（２３℃）に準拠して測定する。
【００３８】
本発明で核剤として用いる高密度ポリエチレンの製造は、目的の物性を有する重合体を製造し得る限りその重合方法や触媒について特に制限はないが、中圧法プロセスによって得られるポリエチレンが好適である。
触媒については、チーグラー型触媒（すなわち、担持または非担持ハロゲン含有チタン化合物と有機アルミニウム化合物の組み合わせに基づくもの）、カミンスキー型触媒（すなわち、担持または非担持メタロセン化合物と有機アルミニウム化合物、特にアルモキサンの組み合わせに基づくもの）が挙げられる。
チーグラー型触媒としては、例えば、ハロゲン化マグネシウム、ハロゲン化チタン、および電子供与体化合物を成分とする固体触媒成分と有機アルミニウム化合物との組み合わせ触媒を用いて通常の重合法により得ることができる。
ポリエチレンの形状は限定されるものでなく、ペレット状、粉末状、ワックス状いずれであってもよい。
【００３９】
本発明で用いるプロピレン系樹脂層に核剤を配合する場合、核剤の配合量は、成分（Ａ）；１００重量部に対して、核剤；０．０１〜５重量部である。また、用いる核剤によって好ましい範囲は異なり、ソルビトール誘導体やリン酸塩化合物、安息香酸塩化合物の場合は、好ましくは成分（Ａ）；１００重量部に対して、核剤；０．０１〜３重量部、より好ましくは成分（Ａ）；１００重量部に対して、核剤；０．０１〜１重量部、特に好ましくは成分（Ａ）；１００重量部に対して、核剤；０．０１〜０．５重量部である。高密度ポリエチレン（Ｃ）の場合には、好ましくは成分（Ａ）；１００重量部に対して、成分（Ｃ）；０．１〜５重量部、より好ましくは成分（Ａ）；１００重量部に対して、成分（Ｃ）；０．５〜３重量部、特に好ましくは（Ａ）成分；１００重量部に対して、成分（Ｃ）；１００重量部である。成分（Ｃ）が０．０１重量部未満ではフィルム透明性改良効果が充分ではなく、一方、５重量部を超えるとポリエチレンがフィルム中で連続層を形成し、フィルム透明性が損なわれる、成分（Ｃ）が凝集してブツになるといった問題が生じる。
【００４０】
（３）その他の配合成分
本発明のプロピレン系樹脂層の構成成分には、本発明の効果を著しく損なわない範囲で、他の付加的任意成分を配合することができる。このような任意成分としては、通常のポリオレフィン樹脂材料に使用される酸化防止剤、透明化剤、滑剤、アンチブロッキング剤、帯電防止剤、防曇剤、中和剤、金属不活性剤、着色剤、分散剤、過酸化物、充填剤、蛍光増白剤等を挙げることができる。
また、発明の効果を損なわない範囲で、高圧ラジカル重合法低密度ポリエチレン、線状低密度ポリエチレン、エチレン・α−オレフィン共重合体、アイソタクチックポリプロピレン、プロピレン・α−オレフィンブロック共重合体、オレフィン系エラストマー等を混合することもできる。
【００４１】
（４）樹脂組成物の調製
プロピレン系樹脂層に用いる成分（Ａ）を主成分とする材料は、上記必須成分（Ａ）と必要に応じて配合される、核剤、付加的成分等とを混合し、溶融混練することにより得られる。
溶融混練は、例えば粉末状、ペレット状等の形状の各成分を一軸又は二軸の押出機、バンバリーミキサー、ニーダーブレンダー、ブラベンダープラストグラフ、小型バッチミキサー、連続ミキサー、ミキシングロール等の混練機を使用して行う。混練温度は、一般に１８０〜２７０℃で行われる。また、混練機は上述したものを二種以上を組み合わせることもできる。
【００４２】
２．エチレン系樹脂層
本発明の空冷インフレーション成形多層フィルムのエチレン系樹脂層は、成分（Ｂ）エチレンと炭素数３〜１２のα−オレフィンとのエチレン・α−オレフィン共重合体からなり、下記（Ｂ１）〜（Ｂ２）の特性を有し、好ましくは、メタロセン触媒で重合され、さらに（Ｂ３）〜（Ｂ４）の特性を有する共重合体である。成分（Ｂ）のエチレン・α−オレフィン共重合体の構成モノマー、重合法、及びそれが有する特性について順次に説明する。
【００４３】
（ｉ）モノマー構成
本発明に使用されるエチレン・α−オレフィン共重合体は、エチレンから誘導される構成単位を主成分としたエチレンとα−オレフィンの共重合体である。
コモノマーとして用いられるα−オレフィンは、好ましくは炭素数３〜１２のα−オレフィンである。具体的には、プロピレン、１−ブテン、１−ペンテン、１−ヘキセン、１−オクテン、１−ヘプテン、４−メチル−ペンテン−１、４−メチル−ヘキセン−１、４，４−ジメチルペンテン−１等を挙げることができる。かかるプロピレン・α−オレフィンランダエチレン・プロピレン共重合体ム共重合体の具体例としては、エチレン・プロピレン共重合体、エチレン・１−ブテン共重合体、エチレン・１−ヘキセン共重合体、エチレン・１−オクテン共重合体、エチレン・４−メチル−ペンテン−１共重合体が挙げられる。また、α−オレフィンは、１種または２種以上の組み合わせでもよい。２種のα―オレフィンを組み合わせてターポリマーとする場合は、エチレン・プロピレン・ヘキセンターポリマー、エチレン・ブテン・ヘキセンターポリマー、エチレン・プロピレン・オクテンターポリマー、エチレン・ブテン・オクテンターポリマーが挙げられる。
【００４４】
（ｉｉ）重合触媒及び重合法
本発明で用いるエチレン・α−オレフィン共重合体は、チーグラー触媒、バナジウム触媒、好ましくはメタロセン触媒を使用して製造することができる。製造法は、高圧イオン重合法、気相法、溶液法、スラリー法等が挙げられる。
【００４５】
（ｉｉｉ）特性
（Ｂ１）メルトフローレート（ＭＦＲ：１９０℃、２１．１８Ｎ荷重）
本発明で用いるエチレン・α−オレフィン共重合体のＭＦＲ（１９０℃、２１．１８Ｎ荷重）は、０．１〜２０ｇ／１０分であり、好ましくは０．５〜１０ｇ／１０分であり、より好ましくは１．０〜５ｇ／１０分である。ＭＦＲが０．１ｇ／１０分未満では樹脂圧力が高く成形性が不良になり、２０ｇ／１０分を超えるとバブルが不安定になり成形性が不良になる。
なお、ＭＦＲの測定は、ＪＩＳ−Ｋ６９２１−２：１９９７付属書（１９０℃、２１．１８Ｎ荷重）に準拠して行う。
【００４６】
（Ｂ２）密度
本発明で用いるエチレン・α−オレフィン共重合体の密度は、０．８６０〜０．９２５ｇ／ｃｍ^３であり、好ましくは０．８７０〜０．９２０ｇ／ｃｍ^３であり、より好ましくは０．８８０〜０．９１５ｇ／ｃｍ^３である。密度が０．８６０ｇ／ｃｍ^３未満ではフィルムにベタツキが発生し、０．９２５ｇ／ｃｍ^３を超えるとフィルムの強度が弱くなるため好ましくない。
なお、密度は、ＪＩＳ−Ｋ６９２２−２：１９９７付属書の低密度ポリエチレンの場合に準拠して測定する（２３℃）。
【００４７】
（Ｂ３）α−オレフィンの含有量
本発明で用いるエチレン・α−オレフィン共重合体中のα−オレフィンの含有量は、５〜４０重量％が好ましく、より好ましくは７〜３５重量％、さらに好ましくは９〜３０重量％である。α−オレフィンの含有量が少ない場合、フィルムの衝撃強度、及び低温ヒートシール性が得られず、多すぎる場合は、耐ブロッキング性が損なわれる。ここでα−オレフィン含有量は、下記の条件の^１３Ｃ−ＮＭＲ法によって計測される値である。
装置：日本電子社製 ＪＥＯＬ−ＧＳＸ２７０
濃度：３００ｍｇ／２ｍＬ
溶媒：オルソジクロロベンゼン
【００４８】
（Ｂ４）Ｚ平均分子量（Ｍｚ）と数平均分子量（Ｍｎ）との比（Ｍｚ／Ｍｎ）
本発明で用いるエチレン・α−オレフィン共重合体のゲルパーミエーションクロマトグラフィー（ＧＰＣ）により求めたＺ平均分子量（Ｍｚ）と数平均分子量（Ｍｎ）との比（Ｍｚ／Ｍｎ）は、８．０以下が好ましく、より好ましくは５．０以下である。Ｍｚ／Ｍｎが８．０を超えると透明性が悪化する。
Ｍｚ／Ｍｎを所定の範囲に調整する方法としては、適当なメタロセン触媒を選択する方法等が挙げられる。
なお、Ｍｚ／Ｍｎの測定は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）で行い、測定条件は次の通りである。
装置：ウオーターズ社製ＧＰＣ １５０Ｃ型
検出器：ＭＩＲＡＮ社製 １Ａ赤外分光光度計（測定波長、３．４２μｍ）
カラム：昭和電工社製ＡＤ８０６Ｍ／Ｓ ３本（カラムの較正は東ソー製単分散ポリスチレン（Ａ５００，Ａ２５００，Ｆ１，Ｆ２，Ｆ４，Ｆ１０，Ｆ２０，Ｆ４０，Ｆ２８８の各０．５ｍｇ／ｍｌ溶液）の測定を行い、溶出体積と分子量の対数値を２次式で近似した。また、試料の分子量はポリスチレンとポリエチレンの粘度式を用いてポリエチレンに換算した。ここでポリスチレンの粘度式の係数はα＝０．７２３、ｌｏｇＫ＝−３．９６７であり、ポリエチレンはα＝０．７３３、ｌｏｇＫ＝−３．４０７である。）
測定温度：１４０℃
濃度：２０ｍｇ／１０ｍＬ
注入量：０．２ｍｌ
溶媒：オルソジクロロベンゼン
流速：１．０ｍｌ／分
【００４９】
なお、Ｍｚは、高分子量成分の平均分子量への寄与が大きいので、Ｍｚ／Ｍｎは、Ｍｗ／Ｍｎに比べ高分子量成分の存在を確認しやすい。高分子量成分は、透明性に影響を与える要因であり、高分子量成分が多いと透明性は悪化する。よって、Ｍｚ／Ｍｎは小さい方が好ましい。
【００５０】
本発明のエチレン系樹脂層を構成樹脂成分には、本発明の効果を著しく損なわない範囲で、他の付加的任意成分を配合することができる。このような任意成分としては、通常のポリオレフィン樹脂材料に使用される酸化防止剤、結晶核剤、透明化剤、滑剤、アンチブロッキング剤、帯電防止剤、防曇剤、中和剤、金属不活性剤、着色剤、分散剤、過酸化物、充填剤、蛍光増白剤等を挙げることができる。
また、発明の効果を損なわない範囲で、高圧ラジカル重合法低密度ポリエチレン、線状低密度ポリエチレン、エチレン・α−オレフィン共重合体、アイソタクチックポリプロピレン、プロピレン・α−オレフィンブロック共重合体、オレフィン系エラストマー等を混合することもできる。
【００５１】
３．空冷シンフレーション成形多層フィルム
本発明の空冷インフレーション成形多層フィルムは、複数の押出機及び共押出多層環状ダイ有するを空冷インフレーション成形法により得られる多層フィルムである。
本発明における空冷インフレーション法の好ましい態様は、プロピレン系樹脂層を構成する樹脂とエチレン系樹脂層を構成する樹脂を共押出多層環状ダイ付きの複数押出機により溶融させてチューブ状にして押出し、ブロアーなどから供給される空気を空冷リングから溶融チューブに吹き付けて冷却固化させた後、ガイド板を経てピンチロールにて折り畳み、引取機にて引き取る方法である。この成形方法で使用できる成形機、冷却リング、ブロアー、ガイド板、ピンチロール、及びフィルムの引取機などは広く市場にて使用されている装置で構わず、特別なものは必要としない。本発明における空冷インフレーション成形法フィルムを成形する条件としては、本発明で特定する特性が得られる限り特に限定しないが、成形温度は１７０〜２５０℃、好ましくは１７０〜２００℃、成形速度は５〜５０ｍ／分、好ましくは１０〜４０ｍ／分が好適である。
【００５２】
本発明の多層フィルムの構成は、エチレン系樹脂層／プロピレン系樹脂層／エチレン系樹脂層からなる３層フィルムであり、両表面層にエチレン系樹脂層を配することにより、引裂強度、衝撃強度、低温ヒートシール強度に優れるフィルムが得られる。
【００５３】
本発明の空冷インフレーション成形多層フィルムの引裂強度は、２０Ｎ／ｍｍ以上が好ましく、より好ましくは４０Ｎ／ｍｍ以上である。引裂強度が２０Ｎ／ｍｍ未満では、製品が破袋しやすくなり内容物を安全に包装できないため好ましくない。また、打ち抜き衝撃強度は、１０００ｋｇ／ｃｍ^２以上が好ましく、より好ましくは１４００ｋｇ／ｃｍ^２以上である。打ち抜き衝撃強度が１０００ｋｇ／ｃｍ^２未満では、製品が破袋しやすくなり内容物を安全に包装できないため好ましくない。
なお、本発明におけるフィルムの引裂強度は、ＪＩＳ−Ｋ７１２８（１９９１）に準拠して測定し、打ち抜き衝撃強度は、ＪＩＳ−Ｐ８１３４に準じた試験機を用い、貫通部に鏡面光沢の表面を有した２５．４ｍｍφの半球型の金属製のものを用いて測定する。
【００５４】
さらに、本発明の空冷インフレーション成形多層フィルムのＨＡＺＥは、３％以下であり、好ましくは２．５％以下である。ＨＡＺＥが３％を超えると内容物が鮮明に見えないなど、商品価値に劣り、好ましくない。
なお、本発明におけるフィルムのＨＡＺＥは、ＪＩＳ−Ｋ７１３６−２０００に準拠して測定する。
【００５５】
また、本発明における空冷インフレーション成形フィルムの厚みは、１０〜１５０μｍが好ましい。上記範囲内であれば透明性に優れるフィルムが安定的に成形できるので好ましい。更に、本発明で得られた多層フィルムに対し、通常工業的に採用されている方法によってコロナ放電処理、あるいは火炎処理等の表面処理を施すこともできる。
【００５６】
４．用途
本発明で得られる空冷インフレーション成形フィルムは、従来の技術で得られる空冷インフレーション成形フィルムに比べて、白味がなく、すっきりした透明感があり、包装材料としては極めて商品価値の高いものである。用途としては、特に限定されないが、食品、衣料、医薬、文具、雑貨などの包装用途に好適に用いられる。
【００５７】
【実施例】
以下、本発明を実施例によって具体的に説明するが、本発明はこれらの実施例によって限定されるものではない。なお、実施例、比較例で用いた評価方法及び使用樹脂は、以下の通りである。
【００５８】
１．評価方法
（１）メルトフローレート（ＭＦＲ）：前述の通り、プロピレン・α−オレフィンランダム共重合体のＭＦＲは、ＪＩＳ−Ｋ６９２１−２：１９９７付属書（２３０℃、２１．１８Ｎ荷重）に準拠して測定し、ポリエチレンのＭＦＲは、ＪＩＳ−Ｋ６９２２−２：１９９７付属書（１９０℃、２１．１８Ｎ荷重）に準拠し測定した。
（２）Ｔｍ：前述の通り、ＤＳＣにより測定した。
（３）Ｍｗ／Ｍｎ：前述の通り、ＧＰＣにより測定した。
（４）Ｍｚ／Ｍｎ：前述の通り、ＧＰＣにより測定した。
（５）密度：前述の通り、ＪＩＳ−Ｋ６９２２−２：１９９７付属書（２３℃）に準拠して測定した。
（６）ＨＡＺＥ：前述の通り、ＪＩＳ−Ｋ７１３６−２０００に準拠して測定した。
（７）打ち抜き衝撃強度：ＪＩＳ−Ｐ８１８４に準じた試験機を用い、貫通部に鏡面光沢の表面を有した２５．４ｍｍφに半球型の金属製のものを用いて測定した。
（８）引裂強度：フィルムの引き取り方向をＭＤ方向として、ＪＩＳ−Ｋ７１２８（１９９１）に準拠して測定した。
（９）ヒートシール強度：１５ｍｍ巾に裁断したフィルムの内面が重なるように２枚重ね、東洋精機製熱盤式ヒートシーラーにてシール温度：１００℃、シール圧力：０．２ＭＰａ、シール時間：１．０秒でヒートシールを行い、引張試験機にて５００ｍｍ／分でヒートシール強度を測定した。
【００５９】
２．使用樹脂
（１）成分（Ａ）プロピレン・α−オレフィンランダム共重合体
下記の製造例１〜３で得た（ＰＰ−１）〜（ＰＰ−３）を用いた。物性を表１に示す。
【００６０】
製造例１
（１）触媒の調製
（ｉ）ジメチルシリレンビス（２−メチル−４−（４−クロロフェニル）−４Ｈ−アズレニル）ジルコニウムジクロリドのラセミ体の合成
特開平１０−２２６７１２号公報の実施例１２に記載された方法に従って合成した。
（ｉｉ）イオン交換性層状珪酸塩の化学処理
特開平１１−８０２２９号公報の実施例１に記載された方法に従って製造した。さらに、この化学処理モンモリロナイト２００ｇを内容積３Ｌの攪拌翼のついたガラス製反応器に導入し、ノルマルヘプタン７５０ｍｌ、さらにトリノルマルオクチルアルミニウムのヘプタン溶液（５００ｍｍｏｌ）を加え、室温で攪拌した。１時間後、ノルマルヘプタンにて洗浄（残液率１％未満）し、スラリーを２０００ｍＬに調製した。
（ｉｉｉ）触媒の調製／予備重合
次に、（ｒ）−ジメチルシリレンビス［２−メチル−４−（４−クロロフェニル）−４Ｈ−アズレニル］ジルコニウムジクロリド３ｍｍｏｌのトルエンスラリー８７０ｍＬとトリイソブチルアルミニウム（１５ｍｍｏｌ）のヘプタン溶液４２．６ｍＬを、あらかじめ室温にて１時間反応させておいた混合液を、上記の化学処理モンモリロナイトスラリーに加え、１時間攪拌した。
続いて、窒素で十分置換を行った内容積１０Ｌの攪拌式オートクレーブにノルマルヘプタン２．１Ｌを導入し、４０℃に保持した。そこに先に調製したモンモリロナイト／錯体スラリーを導入した。温度が４０℃に安定したところでプロピレンを１００ｇ／時間の速度で供給し、その温度を維持した。４時間後、プロピレンの供給を停止し、さらに２時間維持した。回収した予備重合触媒スラリーから、上澄みを約３Ｌ除き、トリイソブチルアルミニウム（３０ｍｍｏｌ）のヘプタン溶液を１７０ｍＬ添加し、１０分間撹拌した後に、４０℃にて減圧下熱処理した。この操作により触媒１ｇ当たりポリプロピレン２．０８ｇを含む予備重合触媒が得られた。
（ｉｖ）プロピレン−エチレンランダム共重合体の製造
内容積２７０Ｌの攪拌装置付き液相重合槽、内容積４００Ｌの失活槽、スラリー循環ポンプ、循環ラインからなる失活システム、二重管式熱交換器と流動フラッシュ槽からなる高圧脱ガスシステム、さらに低圧脱ガス槽および乾燥器などを含む後処理系を組み込んだプロセスにより、プロピレン・エチレン共重合体の連続製造を実施した。
上記で製造した予備重合触媒を流動パラフィン（東燃社製：ホワイトレックス３３５）に濃度１５重量％で分散させて、触媒成分として０．５２ｇ／ｈｒで液相重合槽に導入した。さらにこの重合槽に液状プロピレンを３８ｋｇ／ｈｒ、エチレンを１．３８ｋｇ／ｈｒ、水素を０．２０ｇ／ｈｒ、トリイソブチルアルミニウムを９．０ｇ／ｈｒで連続的に供給し、内温を６２℃に保持し、重合を行った。
液相重合槽からポリマーと液状プロピレンの混合スラリーをポリマーとして１１ｋｇ／ｈｒとなるように失活槽に抜き出した。このとき重合槽の触媒の平均滞留時間は、１．３時間であった。失活槽には、失活剤としてエタノールを１０．５ｇ／ｈｒで供給した。さらにポリマーは、循環ラインから高圧脱ガス槽へ抜き出し、さらに低圧脱ガス槽を経て、乾燥器で乾燥を行った。乾燥器の内温８０℃、滞留時間が１時間となるように調整し、さらに室温の乾燥窒素をパウダーの流れの向流方向に１２ｍ^３／ｈｒの流量で流した。乾燥後のポリマー（ＰＰ−１）は、ホッパーから取り出した。
得られた重合体（ＰＰ−１）は、エチレン含量＝３．３重量％、ＭＦＲ＝７ｇ／１０分、Ｔｍ＝１２５℃、Ｍｗ／Ｍｎ＝２．８であった。
【００６１】
製造例２
製造例１（ｉｖ）において、エチレンを０．７７ｋｇ／ｈｒ、水素を０．１０ｇ／ｈｒ、内温を７０℃にした以外は、製造例１と同様にして、エチレン含量＝２．０重量％、ＭＦＲ＝７ｇ／１０分、Ｔｍ＝１３５℃、Ｍｗ／Ｍｎ＝２．８の重合体（ＰＰ−２）を得た。
【００６２】
製造例３
（１）触媒の調整、予備重合
十分に窒素置換したフラスコに脱水及び脱酸素したｎ−ヘプタン２００ミリリットルを導入し、ついでＭｇＣｌ_２０．４モル、Ｔｉ（Ｏ−ｎ−Ｃ_４Ｈ_９）_４を０．８モル導入し、９５℃に保ちながら２時間反応させた。反応終了後、４０℃に温度を下げ、次いでメチルハイドロジェンポリシロキサン（２０センチストークス）を４８ミリリットル導入し、３時間反応させた。生成した固体成分をｎ−ヘプタンで洗浄した。
次いで、十分に窒素置換したフラスコに生成したｎ−ヘプタンを５０ミリリットル導入し、上記で合成した固体成分をＭｇ原子換算で０．２４モル導入した。さらに、ｎ−ヘプタン２５ミリリットルＳｉＣｌ_４０．４モルを混合して３０℃に保ちながら６０分間かけてフラスコへ導入し、９０℃で３時間反応させた。
これに、さらにｎ−ヘプタン２５ミリリットルにフタル酸クロライド０．０１６モルを混合して、９０℃に保ちながら３０分間かけてフラスコに導入し、９０℃で１時間反応させた。
反応終了後、ｎ−ヘプタンで洗浄した。次いでこれらにＳｉＣｌ_４０．２４ミリモルを導入して、１００℃で３時間反応させた。反応終了後、ｎ−ヘプタンで十分洗浄した。十分に窒素置換したフラスコに十分精製したｎ−ヘプタン５０ミリリットルを導入し、次いで上記で得た固体成分を５グラム導入し、さらに（ＣＨ_３）_３ＣＳｉ（ＣＨ_３）（ＯＣＨ_３）_２を０．８１ミリリットル、３０℃で２時間接触させた。接触終了後、ｎ−ヘプタンで洗浄した。さらに、プロピレンをフローさせて予備重合を実施し、固体触媒を得た。
（２）プロピレン−エチレン−ブテンランダム共重合体の製造
内容積２００リットルの撹拌式オートクレーブ内をプロピレンで十分に置換した後、精製したｎ−ヘプタン６０リットルを導入し、これにトリエチルアルミニウム１５ｇ、上述の固体触媒１．８ｇ（予備重合ポリマーを除いた量として）を５５℃でプロピレン雰囲気下で導入した。さらに気相部水素濃度を６．０容量％に保ちながらプロピレンを５．８ｋｇ／時間のフィード速度で導入し、さらにエチレンを１５５ｇ／時間の速度で導入し、さらに１−ブテンを重合開始２７０分後まで５７０ｇ／時間のフィード速度で導入して６時間重合を実施した。その後、全モノマーの供給を停止し１時間重合を行った。ここでブタノールにて反応を停止させた。その後、生成物をろ過して、乾燥を行い、ＭＦＲ＝８ｇ／１０分、Ｔｍ＝１３２℃、Ｍｗ／Ｍｎ＝３．９、エチレン含量＝２．５重量％、ブテン含量＝８．５重量％のプロピレン・エチレン・１−ブテン共重合体（ＰＰ−３）を得た。
【００６３】
【表１】

【００６４】
（２）成分（Ｂ）エチレン・α−オレフィン共重合体
下記製造例４〜８で得た（ＰＥ−１）〜（ＰＥ−５）及びチーグラー触媒による市販のエチレン・α−オレフィン共重合体（ＰＥ−６）、（ＰＥ−７）を用いた。物性を表２に示す。
【００６５】
製造例４
エチレンとヘキセン−１の共重合体を製造した。触媒の調製は、特表平７−５０８５４５号公報に記載された方法で実施した。即ち、錯体ジメチルシリレンビス（４，５，６，７−テトラヒドロインデニル）ハフニウムジメチル２．０ミリモルに、トリペンタフルオロフェニルホウ素を上記錯体に対して等倍モル加え、トルエンで１０リットルに希釈して触媒溶液を調製した。
内容積１．５リットルの撹拌式オートクレーブ型連続反応器にエチレンと１−ヘキセンとの混合物を１−ヘキセンの組成が６２重量％となるように供給し、反応器内の圧力を１３０ＭＰａに保ち、１４０℃で反応を行った。１時間あたりのポリマー生産量は約２．０ｋｇであった。
反応終了後、１−ヘキセン含有量＝１５重量％、ＭＦＲ＝２．２ｇ／１０分、密度＝０．８９８ｇ／ｃｍ^３、Ｍｚ／Ｍｎ＝３．５のエチレン・α−オレフィン共重合体（ＰＥ−１）を得た。
【００６６】
製造例５
重合時の１−ヘキセンの組成を５５重量％にし、重合温度を１４８℃に代えた以外は製造例１と同様の製法で触媒調整及び重合を行った。１時間あたりのポリマー生産量は約２．１ｋｇであった。
反応終了後、１−ヘキセン含有量＝１２重量％、ＭＦＲ＝２．２ｇ／１０分、密度＝０．９０５ｇ／ｃｍ^３、Ｍｚ／Ｍｎ＝３．５のエチレン・α−オレフィン共重合体（ＰＥ−２）を得た。
【００６７】
製造例６
重合時の１−ヘキセンの組成を７３重量％にし、重合温度を１２７℃に代えた以外は製造例１と同様の製法で触媒調整及び重合を行った。１時間あたりのポリマー生産量は約２．５ｋｇであった。
反応終了後、１−ヘキセン含有量＝２４重量％、ＭＦＲ＝３．５ｇ／１０分、密度＝０．８８０ｇ／ｃｍ^３、Ｍｚ／Ｍｎ＝３．４のエチレン・α−オレフィン共重合体（ＰＥ−３）を得た。
【００６８】
製造例７
重合時の１−ヘキセンの組成を６５重量％にし、重合温度を１５８℃に代えた以外は製造例１と同様の製法で触媒調整及び重合を行った。１時間あたりのポリマー生産量は約３．７ｋｇであった。
反応終了後、１−ヘキセン含有量＝１７重量％、ＭＦＲ＝１６．５ｇ／１０分、密度＝０．８９８ｇ／ｃｍ^３、Ｍｚ／Ｍｎ＝３．５のエチレン・α−オレフィン共重合体（ＰＥ−４）を得た。
【００６９】
製造例８
重合時の１−ヘキセンの組成を４０重量％にし、重合温度を１７０℃に代えた以外は製造例１と同様の製法で触媒調整及び重合を行った。１時間あたりのポリマー生産量は約３．０ｋｇであった。
反応終了後、１−ヘキセン含有量＝７重量％、ＭＦＲ＝４．０ｇ／１０分、密度＝０．９１８ｇ／ｃｍ^３、Ｍｚ／Ｍｎ＝３．８のエチレン・α−オレフィン共重合体（ＰＥ−５）を得た。
【００７０】
【表２】

【００７１】
（３）成分（Ｃ）
高密度ポリエチレン（日本ポリケム（株）製ノバテックＨＪ５８０）、ＭＦＲ：１２ｇ／１０分、密度：０．９６０ｇ／ｃｍ^３
【００７２】
実施例１
プロピレン系樹脂層の成分（Ａ）として（ＰＰ−１）を、エチレン系樹脂層の成分（Ｂ）として（ＰＥ−１）を用い、それぞれ口径５０ｍｍの押出機に装着した直径８０ｍｍ、リップ巾１ｍｍの環状ダイより１９０℃にて溶融押出し、ブロー比＝２、引き取り速度４０ｍ／分にて多層空冷インフレーション成形を行い、厚み３０μｍの三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００７３】
実施例２
プロピレン系樹脂層の成分（Ａ）の（ＰＰ−１）１００重量部に成分（Ｃ）の高密度ポリエチレン１重量部を配合した組成物を用いたこと以外は、実施例１と同様にして三層フィルムを得た。得られたフィルムの物性を表１に示す。
【００７４】
実施例３
エチレン系樹脂層の成分（Ｂ）として三井化学（株）製ウルトゼックス１５２０Ｌ（ＰＥ−７）を用いたこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００７５】
実施例４
表３に示すように厚み比を変更したこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００７６】
実施例５
表３に示すように厚みを変更したこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００７７】
実施例６
エチレン系樹脂層の片面を（ＰＥ−５）に変更したこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００７８】
実施例７
エチレン系樹脂層に（ＰＥ−３）を用いたこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００７９】
実施例８
エチレン系樹脂層に（ＰＥ−５）を用いたこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００８０】
実施例９
エチレン系樹脂層に（ＰＥ−２）を用いたこと以外は、実施例２と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００８１】
実施例１０
プロピレン系樹脂層の樹脂として成分（Ａ）の（ＰＰ−２）１００重量部に成分（Ｃ）の高密度ポリエチレン５重量部を配合した組成物を用いたこと以外は、実施例１と同様にして三層フィルムを得た。得られたフィルムの物性を表３に示す。
【００８２】
比較例１
エチレン系樹脂層に日本ポリケム（株）製ノバテックＳＦ９４１（ＰＥ−６）を用いたこと以外は、実施例１と同様にして三層フィルムを得た。得られたフィルムの物性を表４に示す。
【００８３】
比較例２
プロピレン系樹脂層に（ＰＰ−３）を用いたこと以外は、実施例１と同様にして三層フィルムを得た。得られたフィルムの物性を表４に示す。
【００８４】
【表３】

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【表４】

【００８６】
【発明の効果】
本発明の空冷インフレーション成形フィルムは、透明性、引裂強度、衝撃強度、低温ヒートシール製に優れ、包装材料としては極めて商品価値が高く、食品、衣料、医薬、文具、雑貨などの包装用途に好適に用いることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air-cooled inflation molded multilayer film, and particularly to an air-cooled inflation molded multilayer film having good transparency and excellent tear strength, impact strength, and heat sealability.
[0002]
[Prior art]
Conventionally, polypropylene resins have been widely used especially in the food packaging field because they are excellent in tensile strength, rigidity, transparency and the like and excellent in food hygiene such as non-toxicity and odorlessness. Usually, when a polypropylene resin is used in the packaging field, it is often used in the form of a film.
Film production methods include a T-die molding method, a water-cooled inflation method, an air-cooled inflation method, and the like, which are appropriately selected in consideration of economic efficiency, required performance of the film, and the like.
Among these, the air-cooled inflation method has the features that the equipment is simple, the width of the film can be easily changed by adjusting the blow ratio, and the workability is good. Have. However, the air-cooled inflation method has been widely used for polyethylene resins, but is rarely used for polypropylene resins. The reason for this is that if the molding is performed at a high speed, the bubble shakes greatly, so that the film cannot be stably formed, and the orientation strength in the MD direction of the obtained film is remarkably increased so that the longitudinal tear strength is lowered. Because there is. Further, the T-die molding method and the water-cooled inflation method have a problem that even if the propylene-based resin material is used to obtain a transparent film, the air-cooled inflation method cannot obtain transparency at all.
[0003]
In particular, various inventions have been made to solve the problem of transparency. For example, a method using a resin composition comprising a polypropylene having a high molecular weight and a block copolymer having a specific ethylene content and a specific molecular chain (for example, see Patent Document 1) is disclosed. Also disclosed is a method using a resin composition obtained by adding an unsaturated carboxylic acid or a modified polypropylene thereof to a polypropylene resin (see, for example, Patent Document 2). Further, a method for making highly transparent using syndiotactic polypropylene (for example, see Patent Document 3) is disclosed, and a method using a copolymer of polypropylene and alkenylsilane (for example, see Patent Document 4). ) Is disclosed. However, in these methods, it is necessary to use a very special resin, and the improvement in transparency is still insufficient, and transparency similar to the T-die film molding method and the water-cooled inflation molding method is not obtained.
[0004]
[Patent Document 1]
JP 56-84712 A
[Patent Document 2]
JP-A-56-118825
[Patent Document 3]
Japanese Patent Laid-Open No. 7-125064
[Patent Document 4]
JP-A-8-174665
[0005]
[Problems to be solved by the invention]
In view of the above-mentioned problems, the object of the present invention is air-cooled inflation, has high transparency similar to the T-die method and water-cooled inflation, and has excellent tear strength and impact strength, and excellent low-temperature heat sealability. It is to provide a polypropylene film.
[0006]
[Means for Solving the Problems]
As a result of intensive investigations to solve the above problems, the present inventors laminated a specific propylene / α-olefin random copolymer, a specific ethylene and an α-olefin copolymer, and then air-cooled inflation molding. The present inventors have found that a polypropylene film having excellent transparency and excellent tear strength, impact strength, and low-temperature heat sealability can be provided, and the present invention has been completed.
[0007]
  According to a first aspect of the present invention, the air cooling is characterized in that an ethylene resin layer composed of the following component (B) is laminated on both surfaces of a propylene resin layer mainly composed of the following component (A). An inflation molded multilayer film is provided.
Component (A): Propylene / α-olefin random copolymer polymerized using a metallocene catalyst and having the following characteristics (A1) to (A3)
(A1) Melt flow rate (MFR: 230 ° C., 21.18 N load) is 1 to 20 g / 10 minutes
(A2) Melting peak temperature (Tm) by differential thermal scanning calorimeter (DSC) is 110 to 135 ° C.
(A3) The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 1.5 to 3.5.
Ingredient (B):Manufactured using metallocene catalystCopolymer of ethylene and α-olefin having 3 to 12 carbon atoms having the following characteristics (B1) to (B2)
The melt flow rate (MFR: 190 ° C., 21.18 N load) in (B1) is 0.1 to 20 g / 10 min.
(B2) Density is 0.860-0.905g / cm³
(B3) The content of α-olefin is 5 to 40% by weight.
(B4) The ratio (Mz / Mn) of the Z average molecular weight (Mz) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 5.0 or less.
[0009]
  In addition, the first of the present invention2According to the invention of1st inventionIn, the tear strength is 20 N / mm or more, and the punching impact strength is1400kg / cm²That's it, HAZE is2.5%, An air-cooled inflation molded multilayer film is provided.
[0010]
  In addition, the first of the present invention3According to the invention of1st or 2nd inventionThe air-cooled inflation molded multilayer film is characterized in that the propylene-based resin layer is composed of a mixture of 0.1 to 5 parts by weight of the following component (C) with respect to 100 parts by weight of the component (A). The
Component (C): high density polyethylene having the following properties (C1) to (C2)
(C1) Melt flow rate (MFR: 190 ° C., 21.18 N load) is 10 g / 10 min or more
(C2) Density is 0.94 to 0.98 g / cm³
[0011]
  In addition, the first of the present invention4According to the invention,3In any one of the inventions, there is provided an air-cooled inflation molded multilayer film characterized in that the ratio of the propylene-based resin layer to the thickness of the entire multilayer film is 20 to 90%.
[0012]
  In addition, the first of the present invention5According to the invention,4In any one of the inventions, an air-cooled inflation molded multilayer film is provided in which the thickness of the entire multilayer film is 10 to 150 μm.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
DETAILED DESCRIPTION OF THE INVENTION
The air-cooled inflation molded multilayer film of the present invention is a multilayer film in which an ethylene resin layer composed of component (B) is laminated on both sides of a propylene resin layer mainly composed of component (A). Below, the component of each layer, the shaping | molding method of a film, etc. are demonstrated in detail.
[0014]
1. Propylene resin layer
The component which comprises the propylene-type resin layer of the air-cooled inflation molded multilayer film of this invention consists of a composition containing the following component (A) or a nucleating agent as needed.
(1) Component (A)
The component (A) used in the air-cooled inflation molded film of the present invention is a propylene / α-olefin random copolymer that is polymerized using a metallocene catalyst and has the following characteristics (A1) to (A3). The constituent monomer of the propylene / α-olefin copolymer, the polymerization method, and the characteristics of the monomer will be described in order.
[0015]
(I) Monomer composition
The propylene / α-olefin random copolymer used in the present invention is a random copolymer of propylene and α-olefin mainly composed of a structural unit derived from propylene.
The α-olefin used as a comonomer is preferably ethylene or an α-olefin having 4 to 18 carbon atoms. Specifically, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene- 1 etc. can be mentioned. Moreover, as an alpha olefin, 1 type or the combination of 2 or more types may be sufficient.
Specific examples of the propylene / α-olefin random copolymer include propylene / ethylene random copolymer, propylene / 1-butene random copolymer, propylene / 1-hexene random copolymer, propylene / ethylene / 1- Examples include octene random copolymers and propylene / ethylene / 1-butene random copolymers.
The amount of propylene units in the propylene / α-olefin random copolymer is 88 to 99.5% by weight, preferably 91 to 99% by weight, more preferably 92 to 98.5% by weight. The amount of the unit is 0.5 to 12% by weight, preferably 1 to 10% by weight, more preferably 1.5 to 8% by weight. When the amount of propylene units is small, the film cannot be reduced in rigidity and suitable blocking resistance, and when it is too much, the low temperature heat sealability is impaired. Here, the propylene unit and the α-olefin unit have the following conditions.¹³It is a value measured by C-NMR method.
Apparatus: JEOL-GSX270 manufactured by JEOL Ltd.
Concentration: 300 mg / 2 mL
Solvent: Orthodichlorobenzene
[0016]
(Ii) Polymerization catalyst and polymerization method
The propylene / α-olefin random copolymer used in the present invention can be easily produced by polymerization using a metallocene catalyst. The metallocene catalyst is (1) a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton (so-called metallocene compound) and (2) a stable ionic state by reacting with the metallocene compound. The catalyst is composed of a cocatalyst that can be activated and, if necessary, (3) an organoaluminum compound, and any known catalyst can be used. The metallocene compound is preferably a bridged metallocene compound capable of stereoregular polymerization of propylene, and more preferably a bridged metallocene compound capable of isoregular polymerization of propylene.
[0017]
(1) Examples of the metallocene compound include JP-A-60-35007, JP-A-61-130314, JP-A-63-295607, JP-A-1-275609, JP-A-2-41303, and JP-A-2-41303. JP-A-2-131488, JP-A-2-76887, JP-A-3-163088, JP-A-4-300787, JP-A-4-21694, JP-A-5-43616, JP-A-5-209913, JP-A-6 No. 239914, JP-A-7-504934, and JP-A-8-85708.
[0018]
More specifically, methylene bis (2-methylindenyl) zirconium dichloride, ethylenebis (2-methylindenyl) zirconium dichloride, ethylene 1,2- (4-phenylindenyl) (2-methyl-4-phenyl) -4H azulenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (fluorenyl) zirconium dichloride, isopropylidene (4-methylcyclopentadienyl) (3-t-butylindenyl) zirconium dichloride, dimethylsilylene (2-methyl) -4-t-butyl-cyclopentadienyl) (3′-t-butyl-5′-methyl-cyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, dimethylsilylenebis (4,5,5) , 7-tetrahydroindenyl) zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4-phenylindenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-phenylindenyl)] zirconium Dichloride, dimethylsilylenebis [4- (1-phenyl-3-methylindenyl)] zirconium dichloride, dimethylsilylene (fluorenyl) t-butylamidozirconium dichloride, methylphenylsilylenebis [1- (2-methyl-4, ( 1-naphthyl) -indenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4,5-benzoindenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4-phenyl-4H) -Azulenyl ] Zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] Zirconium dichloride, diphenylsilylene bis [1- (2-methyl-4- (4-chlorophenyl) -4H-azulenyl)] zirconium dichloride, dimethylsilylene bis [1- (2-ethyl-4- (3-fluorobiphenylyl) ) -4H-azurenyl)] zirconium dichloride, dimethylgermylenebis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylgermylenebis [1- (2-ethyl-) 4-phenylindenyl)] zirconium Zirconium compounds such as loride can be exemplified. In the above, compounds in which zirconium is replaced with titanium or hafnium can be used in the same manner. In some cases, a mixture of a zirconium compound and a hafnium compound can be used. Further, the chloride can be replaced with other halogen compounds, hydrocarbon groups such as methyl, isobutyl and benzyl, amide groups such as dimethylamide and diethylamide, alkoxide groups such as methoxy group and phenoxy group, hydride groups and the like.
Among these, a metallocene compound in which an indenyl group or an azulenyl group is crosslinked with silicon or a germyl group is preferable.
[0019]
The metallocene compound may be used by being supported on an inorganic or organic compound carrier. The carrier is preferably an inorganic or organic porous compound, specifically, an ion-exchange layered silicate, zeolite, SiO.₂, Al₂O₃, Silica alumina, MgO, ZrO₂TiO₂, B₂O₃, CaO, ZnO, BaO, ThO_2,Inorganic compounds such as porous polyolefin, organic compounds composed of styrene / divinylbenzene copolymer, olefin / acrylic acid copolymer, or a mixture thereof.
[0020]
(2) Co-catalysts that can be activated to a stable ionic state by reacting with metallocene compounds include organoaluminum oxy compounds (for example, aluminoxane compounds), ion-exchange layered silicates, Lewis acids, boron-containing compounds, ionic compounds And fluorine-containing organic compounds.
[0021]
(3) Examples of organoaluminum compounds include trialkylaluminum such as triethylaluminum, triisopropylaluminum, and triisobutylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, alkylaluminum hydride, and organoaluminum alkoxide. Can be mentioned.
[0022]
Examples of the polymerization method include a slurry method using an inert solvent in the presence of the catalyst, a solution method, a gas phase method substantially using no solvent, or a bulk polymerization method using a polymerization monomer as a solvent. . As a method for obtaining the propylene / α-olefin copolymer specified by the present invention, for example, by adjusting the polymerization temperature and the comonomer amount and appropriately controlling the molecular weight and the distribution of crystallinity, a desired polymer can be obtained. Can do.
[0023]
Further, the propylene / α-olefin random copolymer may be appropriately selected from those commercially available as metallocene polypropylene. Examples of commercially available products include “Wintech” manufactured by Nippon Polychem.
[0024]
(A1) Melt flow rate (MFR: 230 ° C., 21.18 N load)
The MFR (230 ° C., 21.18 N load) of the propylene / α-olefin random copolymer used in the present invention is 1 to 20 g / 10 minutes, preferably 2 to 20 g / 10 minutes, more preferably 4 to 15 g / 10. Minutes. When the MFR is less than the above range, the extrudability is lowered, a suitable productivity cannot be obtained, and further transparency cannot be obtained. When the above range is exceeded, the strength of the film is lowered, and the stability of the tube in air-cooled inflation molding is deteriorated, which is not preferable. In order to adjust the MFR of the polymer, for example, a method of appropriately adjusting the polymerization temperature, the amount of catalyst, the supply amount of hydrogen as a molecular weight regulator and the like is employed.
In addition, the measurement of MFR is performed based on JIS-K6921-2: 1997 appendix (230 degreeC, 21.18N load).
[0025]
(A2) Melting peak temperature (Tm)
The propylene / α-olefin random copolymer used in the present invention has a melting peak temperature (Tm) by a differential scanning calorimeter (DSC) of 110 to 135 ° C, preferably 110 to 130 ° C, more preferably 110 to 125 ° C. is there. When Tm is less than the above range, a decrease in rigidity and suitable blocking resistance cannot be obtained, and when it exceeds the above range, low temperature heat sealability is impaired.
Tm can be affected by the α-olefin content, the type thereof, the regioregularity of the propylene structural unit, and the like. When the α-olefin is ethylene, the content is about 1 to 5% by weight, and when the α-olefin is 1-butene, the content is about 3 to 15% by weight.
The adjustment of Tm can be appropriately adjusted by controlling the type and amount of α-olefin to be copolymerized.
The Tm measurement was performed using a Seiko DSC, taking a sample amount of 5.0 mg, holding at 170 ° C. for 5 minutes, and then crystallizing to −10 ° C. at a rate of temperature drop of 10 ° C./minute for 1 minute. The melting peak temperature (Tm) when held and further melted at a heating rate of 10 ° C./min is evaluated.
[0026]
(A3) Weight average molecular weight (Mw) / Number average molecular weight (Mn)
The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the propylene / α-olefin random copolymer used in the present invention is 1.5 to 3.5, preferably 1.8. To 3.3, more preferably 2.0 to 3.0. When Mw / Mn exceeds the above range, the transparency is lowered, which is not preferable. When the Mw / Mn is less than the above range, processability is deteriorated, for example, an extrusion load increases or shark skin is easily generated. .
Examples of a method for adjusting Mw / Mn within a predetermined range include a method for selecting an appropriate metallocene catalyst.
In addition, the measurement of Mw / Mn is performed by gel permeation chromatography (GPC), and the measurement conditions are as follows.
Apparatus: Waters GPC 150C type
Detector: 1A infrared spectrophotometer manufactured by MIRAN (measurement wavelength: 3.42 μm)
Column: Showa Denko Co., Ltd. AD806M / S 3 (column calibration is Tosoh monodisperse polystyrene (A500, A2500, F1, F2, F4, F10, F20, F40, F288 each 0.5 mg / ml solution) The logarithm of the elution volume and molecular weight was approximated by a quadratic equation, and the molecular weight of the sample was converted to polypropylene using the viscosity equation of polystyrene and polypropylene, where the coefficient of the viscosity equation of polystyrene was α = 0. .723, log K = −3.967, and polypropylene has α = 0.707 and log K = −3.616.)
Measurement temperature: 140 ° C
Concentration: 20 mg / 10 mL
Injection volume: 0.2ml
Solvent: Orthodichlorobenzene
Flow rate: 1.0 ml / min
[0027]
(2) Nucleating agent
The component constituting the propylene resin layer of the air-cooled inflation molded multilayer film of the present invention may contain a nucleating agent in the component (A), and it is preferable from the viewpoint of transparency that the nucleating agent is blended.
[0028]
As a nucleating agent mix | blended with a component (A), what is necessary is just to improve the progress rate of the crystal nucleus production | generation process of a propylene and an alpha olefin random copolymer. Generally, crystallization of polypropylene consists of two processes: a crystal nucleation process and a crystal growth process. In the crystal nucleation process, the temperature difference from the crystallization temperature and the orientation behavior of molecular chains The rate of non-uniform crystal nucleation is significantly increased due to the presence of a substance that affects the speed, particularly through the adsorption of molecular chains and the like, and promotes molecular chain orientation.
[0029]
Specific examples of the nucleating agent include dibenzylidene sorbitol or a derivative thereof, an organic phosphate compound or a metal salt thereof, an aromatic sulfonate or a metal salt thereof, an organic carboxylic acid or a metal salt thereof, a rosin acid partial metal salt, talc, etc. Inorganic fine particles, imides, amides, quinacridonequinones, crystalline polymer compounds such as high-density polyethylene, or mixtures thereof. Among them, a dibenzylidene sorbitol derivative, an organic phosphate metal salt, an organic carboxylic acid metal salt, high-density polyethylene and the like are less likely to generate odor and are suitable for foods.
[0030]
A film formed using a resin containing a dibenzylidene sorbitol derivative is particularly suitable for packaging toys, stationery, and the like because of its excellent transparency and large display effect. Specific examples of dibenzylidene sorbitol derivatives include 1,3: 2,4-bis (o-3,4-dimethylbenzylidene) sorbitol, 1,3: 2,4-bis (o-2,4-dimethyl). Benzylidene) sorbitol, 1,3: 2,4-bis (o-4-ethylbenzylidene) sorbitol, 1,3: 2,4-bis (o-4-chlorobenzylidene) sorbitol, 1, 3: 2,4-dibenzylidene sorbitol.
[0031]
A film formed using a resin containing an organophosphate metal salt is suitable for food packaging because it is particularly excellent in odor and hygiene. Specific examples of the organic phosphate metal salt include compounds represented by the following general formula (I).
[0032]
[Chemical 1]

[0033]
(Wherein R¹Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R²And R³Each represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. M represents an alkali metal, alkaline earth metal, aluminum, or zinc. When M is an alkali metal, m represents 0, n represents 1, and when M is a divalent metal, n represents 1 or 2. , When n is 1, m is 1, when n is 2, m is 0, when M is aluminum, m is 1, and n is 2. )
[0034]
A film formed using a resin containing a metal salt of benzoic acid is suitable for general-purpose packaging because it is particularly economical and inexpensive. Specific examples of the metal benzoate include hydroxy-di (t-butylbenzoate) aluminum.
[0035]
A film formed using a resin containing high-density polyethylene is particularly excellent in processing stability, and thus is excellent in high-speed moldability and suitable for all packaging film applications. What is preferable as the high density polyethylene is a high density polyethylene (C) component having the following properties (C1) and (C2).
[0036]
(C1) Melt flow rate (MFR: 190 ° C., 21.18 N load)
MFR (190 degreeC, 21.18N load) of the high density polyethylene used by this invention is 10 g / 10min or more, Preferably it is 10-3000 g / 10min. When the MFR of the high-density polyethylene is less than 10 g / 10 minutes, the dispersion diameter of the polyethylene is not sufficiently reduced, and the dispersed particles are reflected as irregularities on the film surface, leading to deterioration of transparency. In order to finely disperse polyethylene, the melt flow rate of high-density polyethylene is preferably larger than the melt flow rate of propylene / α-olefin copolymer.
In addition, MFR of high density polyethylene is measured based on JIS-K6922-2: 1997 appendix (190 degreeC, 21.18N load).
[0037]
(C2) Density
The density of the high density polyethylene used in the present invention is 0.94 to 0.98 g / cm.³, Preferably 0.95 to 0.98 g / cm³More preferably, 0.96-0.98 g / cm³It is. The density of the high density polyethylene is 0.94 g / cm³Is less than 0.98 g / cm, the transparency improving effect is not sufficient.³It is difficult to produce polyethylene that exceeds.
In addition, the density of a high density polyethylene is measured based on JIS-K6922-2: 1997 appendix (23 degreeC).
[0038]
Production of high density polyethylene used as a nucleating agent in the present invention is not particularly limited with respect to the polymerization method and catalyst as long as a polymer having the desired physical properties can be produced, but polyethylene obtained by an intermediate pressure process is preferred.
For catalysts, Ziegler type catalysts (ie, based on a combination of supported or unsupported halogen-containing titanium compounds and organoaluminum compounds), Kaminsky type catalysts (ie, supported or unsupported metallocene compounds and organoaluminum compounds, especially alumoxanes). Based on the combination).
The Ziegler-type catalyst can be obtained by a normal polymerization method using, for example, a combination catalyst of a solid catalyst component and an organoaluminum compound containing magnesium halide, titanium halide, and an electron donor compound as components.
The shape of polyethylene is not limited, and may be any of pellets, powders, and waxes.
[0039]
When mix | blending a nucleating agent with the propylene-type resin layer used by this invention, the compounding quantity of a nucleating agent is a nucleating agent; 0.01-5 weight part with respect to 100 weight part of component (A). The preferred range varies depending on the nucleating agent to be used. In the case of a sorbitol derivative, a phosphate compound, or a benzoate compound, the nucleating agent is preferably 0.01 to 3 parts by weight relative to 100 parts by weight of component (A). Parts, more preferably component (A); nucleating agent to 0.01 parts by weight; 0.01 to 1 part by weight, particularly preferably component (A); nucleating agent to 100 parts by weight; 0.01 to 0.5 parts by weight. In the case of high density polyethylene (C), preferably component (A); 0.1 to 5 parts by weight, more preferably component (A); On the other hand, component (C): 0.5 to 3 parts by weight, particularly preferably component (C): 100 parts by weight relative to 100 parts by weight of component (A). If the component (C) is less than 0.01 parts by weight, the effect of improving the film transparency is not sufficient. On the other hand, if it exceeds 5 parts by weight, the polyethylene forms a continuous layer in the film and the film transparency is impaired. There arises a problem that C) is aggregated to form a lump.
[0040]
(3) Other ingredients
The constituent components of the propylene-based resin layer of the present invention can be blended with other additional optional components as long as the effects of the present invention are not significantly impaired. Examples of such optional components include antioxidants, clarifying agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, neutralizing agents, metal deactivators, and colorants used in ordinary polyolefin resin materials. , Dispersants, peroxides, fillers, fluorescent brighteners, and the like.
In addition, the high pressure radical polymerization method low density polyethylene, linear low density polyethylene, ethylene / α-olefin copolymer, isotactic polypropylene, propylene / α-olefin block copolymer, olefin, as long as the effects of the invention are not impaired. It is also possible to mix a system elastomer or the like.
[0041]
(4) Preparation of resin composition
The material mainly composed of the component (A) used for the propylene-based resin layer is prepared by mixing the essential component (A) and a nucleating agent, additional components, etc., which are blended as necessary, and melt-kneading. can get.
For melt kneading, for example, each component in the form of powder, pellets, etc. is mixed with a uniaxial or biaxial extruder, Banbury mixer, kneader blender, Brabender plastograph, small batch mixer, continuous mixer, mixing roll, etc. Use to do. The kneading temperature is generally 180 to 270 ° C. Moreover, a kneader can also combine 2 or more types of what was mentioned above.
[0042]
2. Ethylene resin layer
The ethylene-based resin layer of the air-cooled inflation molded multilayer film of the present invention comprises an ethylene / α-olefin copolymer of component (B) ethylene and an α-olefin having 3 to 12 carbon atoms, and the following (B1) to (B2 ), Preferably a copolymer polymerized with a metallocene catalyst and further having the characteristics (B3) to (B4). The constituent monomer of the ethylene / α-olefin copolymer of component (B), the polymerization method, and the properties possessed by it will be described in order.
[0043]
(I) Monomer composition
The ethylene / α-olefin copolymer used in the present invention is a copolymer of ethylene and an α-olefin mainly composed of structural units derived from ethylene.
The α-olefin used as a comonomer is preferably an α-olefin having 3 to 12 carbon atoms. Specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene- 1 etc. can be mentioned. Specific examples of the propylene / α-olefin-landaethylene / propylene copolymer copolymer include ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, ethylene / propylene copolymer, Examples thereof include 1-octene copolymer and ethylene / 4-methyl-pentene-1 copolymer. Moreover, 1 type or 2 or more types of combinations may be sufficient as an alpha olefin. When combining two types of α-olefins into terpolymers, ethylene / propylene / hexcenter polymers, ethylene / butene / hexcenter polymers, ethylene / propylene / octene terpolymers, and ethylene / butene / octene terpolymers are listed. .
[0044]
(Ii) Polymerization catalyst and polymerization method
The ethylene / α-olefin copolymer used in the present invention can be produced using a Ziegler catalyst, a vanadium catalyst, preferably a metallocene catalyst. Examples of the production method include a high-pressure ion polymerization method, a gas phase method, a solution method, and a slurry method.
[0045]
(Iii) Characteristics
(B1) Melt flow rate (MFR: 190 ° C., 21.18 N load)
The MFR (190 ° C., 21.18 N load) of the ethylene / α-olefin copolymer used in the present invention is 0.1 to 20 g / 10 minutes, preferably 0.5 to 10 g / 10 minutes. Preferably it is 1.0-5 g / 10min. If the MFR is less than 0.1 g / 10 minutes, the resin pressure is high and the moldability becomes poor, and if it exceeds 20 g / 10 minutes, the bubbles become unstable and the moldability becomes poor.
In addition, the measurement of MFR is performed based on JIS-K6921-2: 1997 appendix (190 degreeC, 21.18N load).
[0046]
(B2) Density
The density of the ethylene / α-olefin copolymer used in the present invention is 0.860 to 0.925 g / cm.³Preferably 0.870-0.920 g / cm³And more preferably 0.880 to 0.915 g / cm³It is. Density is 0.860 g / cm³If it is less than that, the film will become sticky, 0.925 g / cm³Exceeding this is not preferable because the strength of the film becomes weak.
In addition, a density is measured based on the case of the low density polyethylene of JIS-K6922-2: 1997 appendix (23 degreeC).
[0047]
(B3) Content of α-olefin
The content of α-olefin in the ethylene / α-olefin copolymer used in the present invention is preferably 5 to 40% by weight, more preferably 7 to 35% by weight, and further preferably 9 to 30% by weight. When the α-olefin content is low, the impact strength and low-temperature heat sealability of the film cannot be obtained, and when it is too high, the blocking resistance is impaired. Here, the α-olefin content is as follows:¹³It is a value measured by C-NMR method.
Apparatus: JEOL-GSX270 manufactured by JEOL Ltd.
Concentration: 300 mg / 2 mL
Solvent: Orthodichlorobenzene
[0048]
(B4) Ratio of Z average molecular weight (Mz) to number average molecular weight (Mn) (Mz / Mn)
The ratio (Mz / Mn) of the Z average molecular weight (Mz) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) of the ethylene / α-olefin copolymer used in the present invention is 8.0. The following is preferable, and more preferably 5.0 or less. When Mz / Mn exceeds 8.0, transparency deteriorates.
Examples of a method for adjusting Mz / Mn to a predetermined range include a method for selecting an appropriate metallocene catalyst.
In addition, the measurement of Mz / Mn is performed by gel permeation chromatography (GPC), and the measurement conditions are as follows.
Apparatus: Waters GPC 150C type
Detector: 1A infrared spectrophotometer manufactured by MIRAN (measurement wavelength: 3.42 μm)
Column: Showa Denko Co., Ltd. AD806M / S 3 (column calibration is Tosoh monodisperse polystyrene (A500, A2500, F1, F2, F4, F10, F20, F40, F288 each 0.5 mg / ml solution) The logarithm of the elution volume and molecular weight was approximated by a quadratic equation, and the molecular weight of the sample was converted to polyethylene using the viscosity equation of polystyrene and polyethylene, where the coefficient of the viscosity equation of polystyrene was α = 0. .723, log K = −3.967, and polyethylene has α = 0.733 and log K = −3.407.)
Measurement temperature: 140 ° C
Concentration: 20 mg / 10 mL
Injection volume: 0.2ml
Solvent: Orthodichlorobenzene
Flow rate: 1.0 ml / min
[0049]
Since Mz contributes greatly to the average molecular weight of the high molecular weight component, Mz / Mn is easier to confirm the presence of the high molecular weight component than Mw / Mn. The high molecular weight component is a factor that affects the transparency, and when the high molecular weight component is large, the transparency is deteriorated. Therefore, a smaller Mz / Mn is preferable.
[0050]
Other additional optional components can be blended with the constituent resin components of the ethylene-based resin layer of the present invention as long as the effects of the present invention are not significantly impaired. Examples of such optional components include antioxidants, crystal nucleating agents, clearing agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, neutralizing agents, and metal inertness used in ordinary polyolefin resin materials. Agents, colorants, dispersants, peroxides, fillers, fluorescent brighteners and the like.
In addition, the high pressure radical polymerization method low density polyethylene, linear low density polyethylene, ethylene / α-olefin copolymer, isotactic polypropylene, propylene / α-olefin block copolymer, olefin, as long as the effects of the invention are not impaired. It is also possible to mix a system elastomer or the like.
[0051]
3. Air-cooled symphonic molded multilayer film
The air-cooled inflation molded multilayer film of the present invention is a multilayer film obtained by an air-cooled inflation molding method having a plurality of extruders and a co-extrusion multilayer annular die.
In a preferred embodiment of the air-cooled inflation method in the present invention, the resin constituting the propylene-based resin layer and the resin constituting the ethylene-based resin layer are melted by a plurality of extruders with a co-extrusion multilayer annular die and extruded into a tube shape, and blower In this method, air supplied from an air cooling ring is blown from a cooling ring to a melting tube to be cooled and solidified, and then folded by a pinch roll through a guide plate and taken by a take-up machine. A molding machine, a cooling ring, a blower, a guide plate, a pinch roll, a film take-up machine, and the like that can be used in this molding method may be apparatuses widely used in the market, and no special ones are required. The conditions for molding the air-cooled inflation molding film in the present invention are not particularly limited as long as the characteristics specified in the present invention are obtained, but the molding temperature is 170 to 250 ° C, preferably 170 to 200 ° C, and the molding speed is 5 to 5. 50 m / min, preferably 10 to 40 m / min is suitable.
[0052]
The structure of the multilayer film of the present invention is a three-layer film composed of an ethylene-based resin layer / propylene-based resin layer / ethylene-based resin layer. By arranging an ethylene-based resin layer on both surface layers, tear strength and impact strength are obtained. A film having excellent low-temperature heat seal strength can be obtained.
[0053]
The tear strength of the air-cooled inflation molded multilayer film of the present invention is preferably 20 N / mm or more, more preferably 40 N / mm or more. A tear strength of less than 20 N / mm is not preferable because the product easily breaks and the contents cannot be safely packaged. The punching impact strength is 1000 kg / cm²Or more, more preferably 1400 kg / cm²That's it. Punching impact strength is 1000kg / cm²If it is less than 1, it is not preferable because the product easily breaks and the contents cannot be safely packaged.
In addition, the tear strength of the film in the present invention was measured according to JIS-K7128 (1991), and the punching impact strength was a specular gloss surface at the penetrating portion using a testing machine according to JIS-P8134. It is measured using a hemispherical metal 25.4 mmφ.
[0054]
Furthermore, the HAZE of the air-cooled inflation molded multilayer film of the present invention is 3% or less, preferably 2.5% or less. If the value of HAZE exceeds 3%, the contents are not clearly visible, such as the contents are not clearly visible.
In addition, HAZE of the film in this invention is measured based on JIS-K7136-2000.
[0055]
The thickness of the air-cooled inflation molded film in the present invention is preferably 10 to 150 μm. If it is in the said range, since the film excellent in transparency can be shape | molded stably, it is preferable. Furthermore, the multilayer film obtained in the present invention can be subjected to a surface treatment such as corona discharge treatment or flame treatment by a method generally employed industrially.
[0056]
4). Application
The air-cooled inflation molded film obtained by the present invention has no whiteness and a clear transparency as compared with the air-cooled inflation molded film obtained by the conventional technique, and is extremely high in commercial value as a packaging material. Although it does not specifically limit as a use, It uses suitably for packaging uses, such as a foodstuff, clothing, a medicine, stationery, and miscellaneous goods.
[0057]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation methods and resins used in the examples and comparative examples are as follows.
[0058]
1. Evaluation methods
(1) Melt flow rate (MFR): As described above, the MFR of the propylene / α-olefin random copolymer is measured in accordance with JIS-K6921-2: 1997 appendix (230 ° C., 21.18 N load). The MFR of polyethylene was measured in accordance with JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load).
(2) Tm: As described above, measured by DSC.
(3) Mw / Mn: Measured by GPC as described above.
(4) Mz / Mn: Measured by GPC as described above.
(5) Density: As described above, density was measured according to JIS-K6922-2: 1997 appendix (23 ° C.).
(6) HAZE: As described above, measured according to JIS-K7136-2000.
(7) Punching impact strength: Measured using a tester according to JIS-P8184, using a metal with a hemispherical shape of 25.4 mmφ having a specular gloss surface at the penetrating portion.
(8) Tear strength: Measured according to JIS-K7128 (1991) with the film take-up direction as the MD direction.
(9) Heat-sealing strength: Two sheets of film cut to a width of 15 mm are stacked so that the inner surfaces overlap each other, and sealing temperature: 100 ° C., sealing pressure: 0.2 MPa, sealing time: 1 with a Toyo Seiki hot plate heat sealer Heat sealing was performed at 0.0 second, and the heat sealing strength was measured at 500 mm / min with a tensile tester.
[0059]
2. Resin used
(1) Component (A) Propylene / α-olefin random copolymer
(PP-1) to (PP-3) obtained in the following Production Examples 1 to 3 were used. The physical properties are shown in Table 1.
[0060]
Production Example 1
(1) Preparation of catalyst
(I) Synthesis of racemic dimethylsilylenebis (2-methyl-4- (4-chlorophenyl) -4H-azurenyl) zirconium dichloride
The compound was synthesized according to the method described in Example 12 of JP-A-10-226712.
(Ii) Chemical treatment of ion-exchange layered silicate
It was produced according to the method described in Example 1 of JP-A-11-80229. Furthermore, 200 g of this chemically treated montmorillonite was introduced into a glass reactor equipped with a stirring blade having an internal volume of 3 L, 750 ml of normal heptane, and a heptane solution of trinormal octyl aluminum (500 mmol) were added and stirred at room temperature. After 1 hour, the mixture was washed with normal heptane (residual liquid ratio less than 1%) to prepare a slurry of 2000 mL.
(Iii) Catalyst preparation / prepolymerization
Next, 870 mL of a toluene slurry of 3 mmol of (r) -dimethylsilylenebis [2-methyl-4- (4-chlorophenyl) -4H-azurenyl] zirconium dichloride and 42.6 mL of a heptane solution of triisobutylaluminum (15 mmol) were previously added. The liquid mixture which had been reacted at room temperature for 1 hour was added to the chemically treated montmorillonite slurry and stirred for 1 hour.
Subsequently, 2.1 L of normal heptane was introduced into a stirring autoclave having an internal volume of 10 L which had been sufficiently substituted with nitrogen, and maintained at 40 ° C. The previously prepared montmorillonite / complex slurry was introduced there. When the temperature was stabilized at 40 ° C., propylene was supplied at a rate of 100 g / hour, and the temperature was maintained. After 4 hours, the propylene feed was stopped and maintained for another 2 hours. About 3 L of the supernatant was removed from the recovered prepolymerized catalyst slurry, 170 mL of a heptane solution of triisobutylaluminum (30 mmol) was added, stirred for 10 minutes, and then heat-treated at 40 ° C. under reduced pressure. By this operation, a prepolymerized catalyst containing 2.08 g of polypropylene per 1 g of catalyst was obtained.
(Iv) Production of propylene-ethylene random copolymer
A liquid phase polymerization tank with an internal volume of 270 L with a stirrer, an inactivation tank with an internal volume of 400 L, a slurry circulation pump, a deactivation system comprising a circulation line, a high-pressure degassing system comprising a double-tube heat exchanger and a fluidized flash tank, Furthermore, continuous production of propylene / ethylene copolymer was carried out by a process incorporating an aftertreatment system including a low pressure degassing tank and a dryer.
The prepolymerized catalyst produced above was dispersed in liquid paraffin (manufactured by Tonen Inc .: White Rex 335) at a concentration of 15% by weight and introduced into the liquid phase polymerization tank at 0.52 g / hr as a catalyst component. Further, liquid propylene was continuously supplied to the polymerization tank at 38 kg / hr, ethylene at 1.38 kg / hr, hydrogen at 0.20 g / hr, and triisobutylaluminum at 9.0 g / hr, and the internal temperature was 62 ° C. Hold and polymerize.
A mixed slurry of polymer and liquid propylene was extracted from the liquid phase polymerization tank into a deactivation tank as a polymer at 11 kg / hr. At this time, the average residence time of the catalyst in the polymerization tank was 1.3 hours. Ethanol was supplied to the deactivation tank at 10.5 g / hr as a deactivation agent. Further, the polymer was extracted from the circulation line to a high-pressure degassing tank, and further dried through a low-pressure degassing tank and a dryer. Adjust the internal temperature of the dryer to 80 ° C and the residence time to be 1 hour, and further dry dry nitrogen at room temperature 12m in the countercurrent direction of the powder flow.³/ Hr. The polymer (PP-1) after drying was taken out from the hopper.
The obtained polymer (PP-1) had an ethylene content of 3.3% by weight, MFR = 7 g / 10 minutes, Tm = 125 ° C., and Mw / Mn = 2.8.
[0061]
Production Example 2
In Production Example 1 (iv), the ethylene content was 2.0 wt% in the same manner as in Production Example 1, except that ethylene was 0.77 kg / hr, hydrogen was 0.10 g / hr, and the internal temperature was 70 ° C. , MFR = 7 g / 10 min, Tm = 135 ° C., Mw / Mn = 2.8 polymer (PP-2) was obtained.
[0062]
Production Example 3
(1) Preparation of catalyst and prepolymerization
200 ml of dehydrated and deoxygenated n-heptane was introduced into a flask thoroughly purged with nitrogen, and then MgCl₂0.4 mol, Ti (On-C₄H₉)₄Was introduced for 0.8 hour and allowed to react for 2 hours while maintaining the temperature at 95 ° C. After completion of the reaction, the temperature was lowered to 40 ° C., and then 48 ml of methyl hydrogen polysiloxane (20 centistokes) was introduced and reacted for 3 hours. The resulting solid component was washed with n-heptane.
Next, 50 ml of the produced n-heptane was introduced into a sufficiently nitrogen-substituted flask, and 0.24 mol of the solid component synthesized above was introduced in terms of Mg atoms. In addition, n-heptane 25 ml SiCl₄0.4 mol was mixed and introduced into the flask over 60 minutes while maintaining at 30 ° C., and reacted at 90 ° C. for 3 hours.
Further, 0.016 mol of phthalic acid chloride was mixed with 25 ml of n-heptane, introduced into the flask over 30 minutes while maintaining at 90 ° C., and reacted at 90 ° C. for 1 hour.
After completion of the reaction, washing with n-heptane was performed. These are then mixed with SiCl₄0.24 mmol was introduced and reacted at 100 ° C. for 3 hours. After completion of the reaction, it was thoroughly washed with n-heptane. Into a fully nitrogen-substituted flask, 50 ml of fully purified n-heptane is introduced, and then 5 grams of the solid component obtained above is introduced, and further (CH₃)₃CSi (CH₃) (OCH₃)₂Was contacted at 0.81 ml at 30 ° C. for 2 hours. After completion of the contact, it was washed with n-heptane. Furthermore, prepolymerization was carried out by flowing propylene to obtain a solid catalyst.
(2) Production of propylene-ethylene-butene random copolymer
After the inside of the stirred autoclave having an internal volume of 200 liters was sufficiently substituted with propylene, 60 liters of purified n-heptane was introduced, and 15 g of triethylaluminum and 1.8 g of the above-mentioned solid catalyst (amount excluding the prepolymerized polymer) As) was introduced at 55 ° C. in a propylene atmosphere. Further, propylene was introduced at a feed rate of 5.8 kg / hour while maintaining the gas phase hydrogen concentration at 6.0% by volume, ethylene was further introduced at a rate of 155 g / hour, and 1-butene was further introduced for 270 minutes. Polymerization was carried out for 6 hours by introducing at a feed rate of 570 g / hour until later. Thereafter, the supply of all monomers was stopped and polymerization was carried out for 1 hour. Here, the reaction was stopped with butanol. The product is then filtered and dried, MFR = 8 g / 10 min, Tm = 132 ° C., Mw / Mn = 3.9, ethylene content = 2.5 wt%, butene content = 8.5 wt% Of propylene / ethylene / 1-butene copolymer (PP-3) was obtained.
[0063]
[Table 1]

[0064]
(2) Component (B) Ethylene / α-olefin copolymer
(PE-1) to (PE-5) obtained in the following Production Examples 4 to 8 and commercially available ethylene / α-olefin copolymers (PE-6) and (PE-7) using a Ziegler catalyst were used. The physical properties are shown in Table 2.
[0065]
Production Example 4
A copolymer of ethylene and hexene-1 was prepared. The catalyst was prepared by the method described in JP-T-7-508545. That is, to the complex dimethylsilylene bis (4,5,6,7-tetrahydroindenyl) hafnium dimethyl 2.0 mmol, tripentafluorophenyl boron was added in an equimolar amount to the above complex, and diluted to 10 liters with toluene. A catalyst solution was prepared.
A mixture of ethylene and 1-hexene was supplied to a stirred autoclave type continuous reactor having an internal volume of 1.5 liter so that the composition of 1-hexene was 62% by weight, and the pressure in the reactor was maintained at 130 MPa. The reaction was performed at 140 ° C. The amount of polymer produced per hour was about 2.0 kg.
After completion of the reaction, 1-hexene content = 15% by weight, MFR = 2.2 g / 10 min, density = 0.898 g / cm³, Mz / Mn = 3.5 ethylene / α-olefin copolymer (PE-1) was obtained.
[0066]
Production Example 5
Catalyst preparation and polymerization were carried out in the same manner as in Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 55% by weight and the polymerization temperature was changed to 148 ° C. The polymer production per hour was about 2.1 kg.
After completion of the reaction, 1-hexene content = 12 wt%, MFR = 2.2 g / 10 min, density = 0.905 g / cm³, Mz / Mn = 3.5 ethylene / α-olefin copolymer (PE-2) was obtained.
[0067]
Production Example 6
Catalyst preparation and polymerization were carried out in the same manner as in Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 73% by weight and the polymerization temperature was changed to 127 ° C. The polymer production per hour was about 2.5 kg.
After completion of the reaction, 1-hexene content = 24 wt%, MFR = 3.5 g / 10 min, density = 0.880 g / cm³, Mz / Mn = 3.4 ethylene / α-olefin copolymer (PE-3) was obtained.
[0068]
Production Example 7
Catalyst preparation and polymerization were carried out in the same manner as in Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 65% by weight and the polymerization temperature was changed to 158 ° C. The polymer production per hour was about 3.7 kg.
After completion of the reaction, 1-hexene content = 17 wt%, MFR = 16.5 g / 10 min, density = 0.898 g / cm³, Mz / Mn = 3.5 ethylene / α-olefin copolymer (PE-4) was obtained.
[0069]
Production Example 8
Catalyst preparation and polymerization were carried out in the same manner as in Production Example 1 except that the composition of 1-hexene at the time of polymerization was changed to 40% by weight and the polymerization temperature was changed to 170 ° C. The amount of polymer production per hour was about 3.0 kg.
After the reaction, 1-hexene content = 7% by weight, MFR = 4.0 g / 10 min, density = 0.918 g / cm³, Mz / Mn = 3.8 ethylene / α-olefin copolymer (PE-5) was obtained.
[0070]
[Table 2]

[0071]
(3) Component (C)
High density polyethylene (Novatec HJ580 manufactured by Nippon Polychem Co., Ltd.), MFR: 12 g / 10 min, density: 0.960 g / cm³
[0072]
Example 1
Using (PP-1) as the component (A) of the propylene-based resin layer and (PE-1) as the component (B) of the ethylene-based resin layer, each having a diameter of 80 mm and a lip width of 1 mm mounted on an extruder having a diameter of 50 mm Was melt-extruded from a circular die at 190 ° C., and multilayer air-cooled inflation molding was performed at a blow ratio = 2 and a take-off speed of 40 m / min to obtain a three-layer film having a thickness of 30 μm. Table 3 shows the physical properties of the obtained film.
[0073]
Example 2
The same procedure as in Example 1 except that a composition in which 1 part by weight of high-density polyethylene of component (C) was blended with 100 parts by weight of component (A) (PP-1) of the propylene-based resin layer was used. A layer film was obtained. Table 1 shows the physical properties of the obtained film.
[0074]
Example 3
A three-layer film was obtained in the same manner as in Example 2 except that Ultzex 1520L (PE-7) manufactured by Mitsui Chemicals, Inc. was used as the component (B) for the ethylene resin layer. Table 3 shows the physical properties of the obtained film.
[0075]
Example 4
A three-layer film was obtained in the same manner as in Example 2 except that the thickness ratio was changed as shown in Table 3. Table 3 shows the physical properties of the obtained film.
[0076]
Example 5
A three-layer film was obtained in the same manner as in Example 2 except that the thickness was changed as shown in Table 3. Table 3 shows the physical properties of the obtained film.
[0077]
Example 6
A three-layer film was obtained in the same manner as in Example 2 except that one side of the ethylene-based resin layer was changed to (PE-5). Table 3 shows the physical properties of the obtained film.
[0078]
Example 7
A three-layer film was obtained in the same manner as in Example 2 except that (PE-3) was used for the ethylene resin layer. Table 3 shows the physical properties of the obtained film.
[0079]
Example 8
A three-layer film was obtained in the same manner as in Example 2 except that (PE-5) was used for the ethylene resin layer. Table 3 shows the physical properties of the obtained film.
[0080]
Example 9
A three-layer film was obtained in the same manner as in Example 2 except that (PE-2) was used for the ethylene resin layer. Table 3 shows the physical properties of the obtained film.
[0081]
Example 10
The same procedure as in Example 1 was conducted except that a composition in which 5 parts by weight of the high-density polyethylene of component (C) was blended with 100 parts by weight of component (A) (PP-2) was used as the resin for the propylene-based resin layer. A three-layer film was obtained. Table 3 shows the physical properties of the obtained film.
[0082]
Comparative Example 1
A three-layer film was obtained in the same manner as in Example 1 except that Novatec SF941 (PE-6) manufactured by Nippon Polychem Co., Ltd. was used for the ethylene resin layer. Table 4 shows the physical properties of the obtained film.
[0083]
Comparative Example 2
A three-layer film was obtained in the same manner as in Example 1 except that (PP-3) was used for the propylene-based resin layer. Table 4 shows the physical properties of the obtained film.
[0084]
[Table 3]

[0085]
[Table 4]

[0086]
【The invention's effect】
The air-cooled inflation molded film of the present invention is excellent in transparency, tear strength, impact strength, and low-temperature heat-sealing. Can be used.

Claims (5)

An air-cooled inflation molded multilayer film comprising an ethylene resin layer comprising the following component (B) laminated on both surfaces of a propylene resin layer comprising the following component (A) as a main component.
Component (A): propylene / α-olefin random copolymer (A1) melt flow rate (MFR: 230 ° C., 21.18 N) polymerized using a metallocene catalyst and having the following properties (A1) to (A3) (Load) is 1 to 20 g / 10 minutes (A2) Melting peak temperature (Tm) by differential thermal scanning calorimeter (DSC) is 110 to 135 ° C.
(A3) The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 1.5 to 3.5.
Component (B): Melt flow rate (MFR) in a copolymer (B1) of ethylene and an α-olefin having 3 to 12 carbon atoms having the following characteristics (B1) to (B2) produced using a metallocene catalyst : 190 ° C., 21.18 N load) is 0.1 to 20 g / 10 min (B2) density is 0.860 to 0.905 g / cm ³
(B3) The content of α-olefin is 5 to 40% by weight.
(B4) The ratio (Mz / Mn) of the Z average molecular weight (Mz) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 5.0 or less. The air-cooled inflation molded multilayer film according to claim 1, wherein the tear strength is 20 N / mm or more, the punching impact strength is 1400 kg / cm ² or more, and HAZE is 2.5 % or less. The air cooling according to claim 1 or 2, wherein the propylene-based resin layer is composed of a composition in which 0.1 to 5 parts by weight of the following component (C) is blended with 100 parts by weight of the component (A). Inflation molded multilayer film.
Component (C): High density polyethylene (C1) having the following characteristics (C1) to (C2) (C1) Melt flow rate (MFR: 190 ° C., 21.18 N load) is 10 g / 10 min or more (C2) Density is 0.00. 94-0.98 g / cm ³ The ratio of the propylene-type resin layer with respect to the thickness of the whole multilayer film is 20 to 90%, The air-cooled inflation molded multilayer film of any one of Claims 1-3 characterized by the above-mentioned. The thickness of the whole multilayer film is 10-150 micrometers, The air-cooled inflation molded multilayer film of any one of Claims 1-4 characterized by the above-mentioned.