JP3715357B2 - Stretch film - Google Patents

Description

【００１８】
ここで、ｃ_ｊとｂ_ｊはそれぞれｊ番目の区分の相対濃度と分岐度である。組成分布パラメータＣｂは試料の組成が均一である場合に１．０となり、組成分布が広がるに従って値が大きくなる。
【００１９】
エチレン・α−オレフィン共重合体の組成分布を記述する方法は多くの提案がなされている。例えば特開昭６０−８８０１６号公報では、試料を溶剤分別して得た各分別試料の分岐数に対して、累積重量分率が特定の分布（対数正規分布）をすると仮定して数値処理を行い、重量平均分岐度（Ｃｗ）と数平均分岐度（Ｃｎ）の比を求めている。この近似計算は、試料の分岐数と累積重量分率が対数正規分布からずれると精度が下がり、市販のＬＬＤＰＥについて測定を行うと相関係数Ｒ^２はかなり低く、値の精度は充分でない。また、このＣｗ／Ｃｎの測定法および数値処理法は、本発明のＣｂのそれとは異なるが、あえて数値の比較を行えば、Ｃｗ／Ｃｎの値は、Ｃｂよりかなり大きな値となる。
【００２０】
本発明のエチレン・α−オレフィン共重合体の（オ）２５℃におけるＯＤＣＢ可溶分の量は、下記の方法により測定する。
試料０．５ｇを２０ｍｌのＯＤＣＢにて１３５℃で２時間加熱し、試料を完全に溶解した後、２５℃まで冷却する。この溶液を２５℃で一晩放置後、テフロン製フィルターでろ過してろ液を採取する。このろ液のメチレンの非対称伸縮振動の波数２９２５ｃｍ^−１付近の吸収ピーク面積を求め、あらかじめ作成した検量線により試料濃度を算出する。この値より、２５℃におけるＯＤＣＢ可溶分を求める。
【００２１】
本発明の（オ）２５℃におけるＯＤＣＢ可溶分の量、Ｘ重量％と密度ｄおよびＭＦＲの関係は、ｄおよびＭＦＲの値が
ｄ−０．００８ｌｏｇＭＦＲ≧０．９３を満たす場合は、
Ｘは２重量％未満、好ましくは１重量％未満
ｄ−０．００８ｌｏｇＭＦＲ＜０．９３の場合は
Ｘ＜９．８×１０^３×（０．９３００−ｄ＋０．００８ｌｏｇＭＦＲ）^２＋２．０
好ましくは、
Ｘ＜７．４×１０^３×（０．９３００−ｄ＋０．００８ｌｏｇＭＦＲ）^２ ＋１．０
さらに好ましくは、
Ｘ＜５．６×１０^３×（０．９３００−ｄ＋０．００８ｌｏｇＭＦＲ）^２＋０．５
の関係を満足していることが必要である。
【００２２】
２５℃におけるＯＤＣＢ可溶分は、エチレン・α−オレフィン共重合体に含まれる高分岐度成分および低分子量成分であり、衛生性の問題や成形品内面のブロッキングの原因となるためこの含有量は少ないことが望ましい。ＯＤＣＢ可溶分の量は、コモノマーの含有量および分子量に影響される。従ってこれらの指標である密度およびＭＦＲとＯＤＣＢ可溶分の量が上記の関係を満たすことは、共重合体全体に含まれるα−オレフィンの偏在が少ないことを示す。
【００２３】
本発明の（Ａ）エチレン・α−オレフィン共重合体は、（カ）連続昇温溶出分別法（ＴＲＥＦ）により求めた溶出温度−溶出量曲線において、ピークが複数個存在することが必要である。また、さらに８５℃から１００℃の間にピークが存在することが特に好ましい。このピークが存在することにより、成形体の耐熱性が向上する。図１に本発明の共重合体の溶出温度−溶出量曲線を示して図２にいわゆるメタロセン触媒による共重合体との相違を示した。
【００２４】
本発明にかかわるＴＲＥＦの測定方法は下記の通りである。試料を酸化防止剤を加えたＯＤＣＢに試料濃度０．０５重量％となるように１３５℃で加熱溶解する。この試料溶液５ｍｌを、ガラスビーズを充填したカラムに注入し、０．１℃／ｍｉｎの冷却速度で２５℃まで冷却し、試料をガラスビーズ表面に沈着する。次に、このカラムにＯＤＣＢを一定流量で流しながら、カラム温度を５０℃／ｈｒの一定速度で昇温しながら、試料を順次溶出させる。この際、溶剤中に溶出する試料の濃度は、メチレンの非対称伸縮振動の波数２９２５ｃｍ^−１に対する吸収を赤外検出機で連続的に検出される。この値から、溶液中のエチレン・α−オレフィン共重合体の濃度を定量分析し、溶出温度と溶出速度の関係を求める。ＴＲＥＦ分析は極少量の試料で、温度変化に対する溶出速度の変化を連続的に分析出来るため、分別法では検出できない比較的細かいピークの検出が可能である。
【００２５】
本発明の特定のエチレン・α−オレフィン共重合体の製造は、好ましくは以下のＣ１〜Ｃ５からなる触媒で重合することが望ましい。
すなわち、Ｃ１：一般式Ｍｅ^１Ｒ^１ _ｐ（ＯＲ^２）_ｑＸ^１ _{４−ｐ−ｑ}で表される化合物（式中Ｍｅ^１はジルコニウム、チタン、ハフニウムを示し、Ｒ^１およびＲ^２は各々炭素数１〜２４の炭化水素基、Ｘ^１はハロゲン原子を示し、ｐおよびｑは各々０≦ｐ＜４、０≦ｐ＋ｑ≦４の範囲を満たすを整数である）、Ｃ２：一般式Ｍｅ^２Ｒ^３ _ｍ（ＯＲ^４）_ｎＸ^２ _{ｚ−ｍ−ｎ}で表される化合物（式中Ｍｅ^２は周期律表第Ｉ〜ＩＩＩ族元素、Ｒ^３およびＲ^４は各々炭素数１〜２４の炭化水素基、Ｘ^２はハロゲン原子または水素原子（ただし、Ｘ^２が水素原子の場合はＭｅ^２は周期律表第ＩＩＩ族元素の場合に限る）を示し、ｚはＭｅ^２の価数を示し、ｍおよびｎは各々０≦ｍ≦ｚ、０≦ｎ≦ｚの範囲を満たす整数であり、かつ、０≦ｍ＋ｎ≦ｚである）、Ｃ３：共役二重結合を持つ有機環状化合物、およびＣ４：有機アルミニウム化合物と水との反応によって得られるＡｌ−Ｏ−Ａｌ結合を含む変性有機アルミニウム化合物、Ｃ５：無機担体および／または粒子状ポリマー担体を相互に接触させて得られる触媒である。
【００２６】
上記触媒成分Ｃ１の一般式Ｍｅ^１Ｒ^１ _ｐ（ＯＲ^２）_ｑＸ^１ _{４−ｐ−ｑ}で表される化合物の式中Ｍｅ^１はジルコニウム、チタン、ハフニウムを示す。これらの遷移金属の種類は限定されるものではなく、複数を用いることもできるが、共重合体の耐候性の優れるジルコニウムが含まれることが特に好ましい。Ｒ^１およびＲ^２は各々炭素数１〜２４の炭化水素基で、好ましくは炭素数１〜１２、さらに好ましくは１〜８であり、具体的にはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基などのアルキル基；ビニル基、アリル基などのアルケニル基；フェニル基、トリル基、キシリル基、メシチル基、インデニル基、ナフチル基などのアリール基；ベンジル基、トリチル基、フェネチル基、スチリル基、ベンズヒドリル基、フェニルブチル基、ネオフイル基などのアラルキル基などが挙げられる。これらは分岐があってもよい。Ｘ^１はフッ素、ヨウ素、塩素および臭素などのハロゲン原子を示し、ｐおよびｑはそれぞれ０≦ｐ＜４、０≦ｑ＜４、０≦ｐ＋ｑ≦４の範囲を満たし、好ましくは０≦ｐ＋ｑ≦４の範囲である。
【００２７】
上記触媒成分Ｃ１の一般式で示される化合物の例としては、テトラメチルジルコニウム、テトラエチルジルコニウム、テトラベンジルジルコニウム、テトラプロポキシジルコニウム、トリプロポキシモノクロロジルコニウム、テトラブトキシジルコニウム、テトラブトキシチタン、テトラブトキシハフニウムなどが挙げられ、特にテトラプロポキシジルコニウム、テトラブトキシジルコニウムなどのＺｒ（ＯＲ）_４化合物であり、これらを２種以上混合して用いても差し支えない。
【００２８】
上記触媒成分Ｃ２の一般式Ｍｅ^２Ｒ^３ _ｍ（ＯＲ^４）_ｎＸ^２ _{ｚ−ｍ−ｎ}で表される化合物の式中Ｍｅ^２は周期律表第Ｉ〜ＩＩＩ族元素を示し、リチウム、ナトリウム、カリウム、マグネシウム、カルシウム、亜鉛、ホウ素、アルミニウムなどである。Ｒ^３およびＲ^４は各々炭素数１〜２４の炭化水素基、好ましくは炭素数１〜１２、さらに好ましく１〜８であり、具体的にはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基などのアルキル基；ビニル基、アリル基などのアルケニル基；フェニル基、トリル基、キシリル基、メシチル基、インデニル基、ナフチル基などのアリール基；ベンジル基、トリチル基、フェネチル基、スチリル基、ベンズヒドリル基、フェニルブチル基、ネオフイル基などのアラルキル基などが挙げられる。これらは分岐があってもよい。Ｘ^２はフッ素、ヨウ素、塩素および臭素などのハロゲン原子または水素原子を示すものである。ただし、Ｘ^２が水素原子の場合はＭｅ^２はホウ素、アルミニウムなどに例示される周期律表第ＩＩＩ族元素の場合に限るものである。また、ｚはＭｅ^２の価数を示し、ｍおよびｎは各々０≦ｍ≦ｚ、０≦ｎ≦ｚの範囲を満たす整数であり、かつ、０≦ｍ＋ｎ≦ｚである。
【００２９】
上記触媒成分Ｃ２の一般式で示される化合物の例としては、メチルリチウム、エチルリチウムなどの有機リチウム化合物；ジメチルマグネシウム、ジエチルマグネシウム、メチルマグネシウムクロライド、エチルマグネシウムクロライドなどの有機マグネシウム化合物；ジメチル亜鉛、ジエチル亜鉛などの有機亜鉛化合物；トリメチルボロン、トリエチルボロンなどの有機ボロン化合物；トリメチルアルミニウム、トリエチルアルミニウム、トリイソブチルアルミニウム、トリヘキシルアルミニウム、トリデシルアルミニウム、ジエチルアルミニウムクロライド、エチルアルミニウムジクロライド、エチルアルミニウムセスキクロライド、ジエチルアルミニウムエトキサイド、ジエチルアルミニウムハイドライドなどの有機アルミニウム化合物等の誘導体が挙げられる。
【００３０】
上記触媒成分Ｃ３の共役二重結合を持つ有機環状化合物とは、環状で共役二重結合を２個以上、好ましくは２〜４個、さらに好ましくは２〜３個有する環を１個または２個以上もち、全炭素数が４〜２４、好ましくは４〜１２である環状炭化水素化合物；前記環状炭化水素化合物が部分的に１〜６個の炭化水素残基（典型的には、炭素数１〜１２のアルキル基またはアラルキル基）で置換された環状炭化水素化合物；共役二重結合を２個以上、好ましくは２〜４個、さらに好ましくは２〜３個有する環を１個または２個以上もち、全炭素数が４〜２４、好ましくは４〜１２である環状炭化水素基を有する有機ケイ素化合物；前記環状炭化水素基が部分的に１〜６個の炭化水素残基またはアルカリ金属塩（ナトリウムまたはリチウム塩）で置換された有機ケイ素化合物が含まれる。特に好ましくは分子中のいずれかにシクロペンタジエン構造をもつものが望ましい。
【００３１】
上記の好適な化合物としては、シクロペンタジエン、インデン、アズレンまたはこれらのアルキル、アリール、アラルキル、アルコキシまたはアリールオキシ誘導体などが挙げられる。また、これらの化合物がアルキレン基（その炭素数は通常２〜８、好ましくは２〜３）を介して結合（架橋）した化合物も好適に用いられる。
【００３２】
環状炭化水素基を有する有機ケイ素化合物は、下記一般式で表示することができる。
Ａ_ＬＳｉＲ_４−Ｌ
ここで、Ａはシクロペンタジエニル基、置換シクロペンタジエニル基、インデニル基、置換インデニル基で例示される前記環状水素基を示し、Ｒはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基などのアルキル基；メトキシ基、エトキシ基、プロポキシ基、ブトキシ基などのアルコキシ基；フェニル基などのアリール基；フェノキシ基などのアリールオキシ基；ベンジル基などのアラルキル基で示され、炭素数１〜２４、好ましくは１〜１２の炭化水素残基または水素を示し、Ｌは１≦Ｌ≦４、好ましくは１≦Ｌ≦３である。
【００３３】
上記成分Ｃ３の有機環状炭化水素化合物の具体例は、シクロペンタジエン、メチルシクロペンタジエン、エチルシクロペンタジエン、１，３−ジメチルシクロペンタジエン、インデン、４−メチル−１−インデン、４，７−ジメチルインデン、シクロヘプタトリエン、メチルシクロヘプタトリエン、シクロオクタテトラエン、アズレン、フルオレン、メチルフルオレンのような炭素数５〜２４のシクロポリエンまたは置換シクロポリエン、モノシクロペンタジエニルシラン、ビスシクロペンタジエニルシラン、トリスシクロペンタジエニルシラン、モノインデニルシラン、ビスインデニルシラン、トリスインデニルシラン等が挙げられる。
【００３４】
触媒成分Ｃ４の有機アルミニウム化合物と水との反応によって得られるＡｌ−Ｏ−Ａｌ結合を含む変性有機アルミニウム化合物とは、アルキルアルミニウム化合物と水とを反応させることにより、通常アルミノキサンと称される変性有機アルミニウムが得られ、分子中に通常１〜１００個、好ましくは１〜５０個のＡｌ−Ｏ−Ａｌ結合を含有する。また、変性有機アルミニウム化合物は線状でも環状でもいずれでもよい。
【００３５】
有機アルミニウムと水との反応は通常不活性炭化水素中で行われる。該不活性炭化水素としては、ペンタン、ヘキサン、ヘプタン、シクロヘキサン、ベンゼン、トルエン、キシレン等の脂肪族、脂環族、芳香族炭化水素が好ましい。
水と有機アルミニウム化合物との反応比（水／Ａｌモル比）は通常０．２５／１〜１．２／１、好ましくは０．５／１〜１／１であることが望ましい。
【００３６】
触媒成分Ｃ５の無機物担体および／または粒子状ポリマー担体とは、炭素質物、金属、金属酸化物、金属塩化物、金属炭酸塩またはこれらの混合物あるいは熱可塑姓樹脂、熱硬化性樹脂等が挙げられる。該無機物担体に用いることができる好適な金属としては、鉄、アルミニウム、ニッケルなどが挙げられる。
具体的にはＳｉＯ_２、Ａｌ_２Ｏ_３、ＭｇＯ、ＺｒＯ_２、ＴｉＯ_２、Ｂ_２Ｏ_３、ＣａＯ、ＺｎＯ、ＢａＯ、ＴｈＯ_２等またはこれらの混合物が挙げられ、ＳｉＯ_２−Ａｌ_２Ｏ_３、ＳｉＯ_２−Ｖ_２Ｏ_５、ＳｉＯ_２−ＴｉＯ_２、ＳｉＯ_２−Ｖ_２Ｏ_５、ＳｉＯ_２−ＭｇＯ、ＳｉＯ_２−Ｃｒ_２Ｏ_３等が挙げられる。これらの中でもＳｉＯ_２およびＡｌ_２Ｏ_３からなる群から選択された少なくとも１種の成分を主成分とするものが好ましい。
【００３７】
また、有機化合物としては、熱可塑性樹脂、熱硬化性樹脂のいずれも使用でき、具体的には、粒子状のポリオレフィン、ポリエステル、ポリアミド、ポリ塩化ビニル、ポリ（メタ）アクリル酸メチル、ポリスチレン、ポリノルボルネン、各種天然高分子およびこれらの混合物等が挙げられる。
上記無機物担体および／または粒子状ポリマー担体は、このまま使用することもできるが、好ましくは予備処理としてこれらの担体を有機アルミニウム化合物やＡｌ−Ｏ−Ａｌ結合を含む変性有機アルミニウム化合物などに接触処理させた後に成分Ｃ５として用いることもできる。
【００３８】
本発明のエチレン・α−オレフィン共重合体の製造方法は、気相法、スラリー法、溶液法等で製造され、一段重合法、多段重合法など特に限定されるものではない。
【００３９】
本発明の他の（Ｂ）エチレン系重合体とは、チーグラー型触媒等を用いる高・中・低圧法およびその他の公知の方法による（Ｂ１）密度０．８６〜０．９４ｇ／ｃｍ^３のエチレンと炭素数３〜２０のα−オレフィンとの共重合体および／または（Ｂ２）高圧ラジカル重合法によるエチレン系（共）重合体である。
【００４０】
上記、チーグラー型触媒等を用いる高・中・低圧法およびその他の公知の方法による（Ｂ１）密度０．８６〜０．９４ｇ／ｃｍ^３のエチレンと炭素数３〜２０のα−オレフィンとの共重合体とは、密度が０．９１〜０．９４ｇ／ｃｍ^３の線状低密度ポリエチレン（以下ＬＬＤＰＥと称す）、密度が０．８６〜０．９１ｇ／ｃｍ^３の超低密度ポリエチレン（以下ＶＬＤＰＥと称す）、密度が０．８６〜０．９１ｇ／ｃｍ^３のエチレン・プロピレン共重合体ゴム、エチレン・プロピレン・ジエン共重合体ゴム等のエチレン・α−オレフィン共重合体ゴムを包含する。
【００４１】
上記チーグラー型触媒によるＬＬＤＰＥとは、密度が０．９１〜０．９４ｇ／ｃｍ^３、好ましくは０．９１〜０．９３ｇ／ｃｍ^３の範囲のエチレン・α−オレフィン共重合体であり、α−オレフィンは、炭素数３〜２０、好ましくは炭素数４〜１２の範囲のものであり、具体的にはプロピレン、１−ブテン、４−メチル−１−ペンテン、１−ヘキセン、１−オクテン等が挙げられる。
【００４２】
また上記チーグラー型触媒による超低密度ポリエチレン（ＶＬＤＰＥ）とは、密度が０．８６〜０．９１ｇ／ｃｍ^３、好ましくは０．８８〜０．９０５ｇ／ｃｍ^３の範囲のエチレン−α−オレフィン共重合体であり、線状低密度ポリエチレン（ＬＬＤＰＥ）とエチレン・α−オレフィン共重合体ゴム（ＥＰＲ、ＥＰＤＭ）の中間の性状を示すポリエチレンである。
【００４３】
また上記エチレン・α−オレフィン共重合体ゴムとは、密度が０．８６〜０．９１ｇ／ｃｍ^３未満のエチレン・プロピレン共重合体ゴム、エチレン・プロピレン・ジエン共重合体ゴム等が挙げられ、該エチレン・プロピレン系ゴムとしては、エチレンおよびプロピレンを主成分とするランダム共重合体（ＥＰＭ）、および第３成分としてジエンモノマー（ジシクロペンタジエン、エチリデンノルボルネン等）を加えたものを主成分とするランダム共重合体（ＥＰＤＭ）が挙げられる。
【００４４】
前記高圧ラジカル重合によるエチレン（共）重合体とは、高圧ラジカル重合によるエチレン単独重合体（低密度ポリエチレン）、エチレン・ビニルエステル共重合体およびエチレンとα，β−不飽和カルボン酸またはその誘導体との共重合体等が挙げられる。
【００４５】
上記低密度ポリエチレンは公知の高圧ラジカル重合法により製造され、チューブラー法、オートクレーブ法のいずれでもよい。
【００４６】
上記エチレン・ビニルエステル共重合体とは、高圧ラジカル重合法で製造され、エチレンを主成分とし、プロピオン酸ビニル、酢酸ビニル、カプロン酸ビニル、カプリル酸ビニル、ラウリル酸ビニル、ステアリン酸ビニル、トリフルオル酢酸ヒニルなどのビニルエステル単量体との共重合体である。これらの中でも特に好ましいものとしては、酢酸ビニルを挙げることができる。エチレン５０〜９９．５重量％、ビニルエステル０．５〜５０重量％からなる共重合体が好ましい。さらにビニルエステル含有量は好ましくは３〜２０重量％、特に好ましくは５〜１５重量％の範囲で選択される。
【００４７】
さらに上記エチレンとα，β−不飽和カルボン酸またはその誘導体との共重合体の代表的な共重合体としては、エチレン・（メタ）アクリル酸またはそのアルキルエステル共重合体が挙げられ、これらのコモノマーとしては、アクリル酸、メタクリル酸、アクリル酸メチル、メタクリル酸メチル、アクリル酸エチル、メタクリル酸エチル、アクリル酸プロピル、メタクリル酸プロピル、アクリル酸イソプロピル、メタクリル酸イソプロピル、アクリル酸−ｎ−ブチル、メタクリル酸−ｎ−ブチル、アクリル酸シクロヘキシル、メタクリル酸シクロヘキシル、アクリル酸ラウリル、メタクリル酸ラウリル、アクリル酸ステアリル、メタクリル酸ステアリル、アクリル酸グリシジル、メタクリル酸グリシジル等を挙げることができる。この中でも特に好ましいものとして（メタ）アクリル酸のメチル、エチル等のアルキルエステルを挙げることができる。特に（メタ）アクリル酸エステル含有量は３〜２０重量％、好ましくは５〜１５重量％の範囲である。
【００４８】
【発明の実施の形態】
本発明の積層構造からなるストレッチフィルムの態様の一つは、特定の（Ａ）エチレン−α−オレフィン共重合体を含む第Ｉの層と（Ｂ）エチレン系共重合体からなる第ＩＩの層の少なくとも２層の積層体からなるストレッチフィルムである。
該第Ｉの層は、前記特定の（Ａ）エチレン−α−オレフィン共重合体単独または該特定の（Ａ）エチレン−α−オレフィン共重合体と（Ｂ）エチレン系重合体の組成物層で形成されていても良い。上記特定の（Ａ）エチレン−α−オレフィン共重合体と（Ｂ）エチレン系重合体との組成物は、成形安定性、透明性、機械的強度、粘着性、延伸性、結束性等のバランスを考慮した場合は、（Ａ）９８〜２０重量％、（Ｂ）２〜８０重量％、好ましくは（Ａ）９０〜５０重量％、（Ｂ）１０〜５０重量％、さらに好ましくは（Ａ）８０〜６０重量％、（Ｂ）２０〜４０重量％の範囲で選択される。また、第ＩＩの層においても（Ｂ１）チーグラー型触媒による密度０．８６〜０．９４ｇ／ｃｍ^３のエチレン−α−オレフィン共重合体または（Ｂ２）高圧ラジカル重合によるエチレン（共）重合体を単独または混合組成物として使用してもよい。
【００４９】
これらの具体的な組合せとしては、ＭＬＬ／ＥＶＡ、（ＭＬＬ＋ＬＤ）／ＥＶＡ、（ＭＬＬ＋ＬＬ）／ＥＶＡ、（ＭＬＬ＋ＥＶＡ）／ＥＶＡ、ＭＬＬ／（ＥＶＡ＋ＬＤ）、ＭＬＬ／（ＥＶＡ＋ＬＬ）、（ＭＬＬ＋ＥＶＡ）／（ＥＶＡ＋ＬＬ）、ＭＬＬ／ＥＥＡ、（ＭＬＬ＋ＬＤ）／ＥＥＡ、（ＭＬＬ＋ＶＬ）／ＥＥＡ、（ＭＬＬ＋ＥＶＡ）／ＥＥＡ、ＭＬＬ／（ＥＶＡ＋ＥＥＡ）等が挙げられる。
（ただし、ＭＬＬ：本発明の（Ａ）エチレン−α−オレフィン共重合体、ＥＶＡ：エチレン−酢酸ビニル共重合体、ＬＤ：高圧ラジカル法低密度ポリエチレン、ＬＬ：線状低密度ポリエチレン、ＶＬ：超低密度ポリエチレン、ＥＥＡ：エチレン−アクリル酸エチル共重合体を示す）
【００５０】
本発明の積層構造からなるストレッチフィルムの他の態様は、前記第Ｉの層の両面に（Ｂ１）チーグラー型触媒による密度０．８６〜０．９４ｇ／ｃｍ^３のエチレン−α−オレフィン共重合体または（Ｂ２）高圧ラジカル重合によるエチレン（共）重合体の少なくとも１種の（Ｂ）エチレン系重合体からなる第ＩＩの層と第ＩＩＩの層を設けた積層体からなるストレッチフィルムであり、第Ｉの層、第ＩＩの層および第ＩＩＩの層は、同種または異種並びに混合物層で形成されていてもよい。
【００５１】
これらの具体的な組合せとしては、ＥＶＡ／ＭＬＬ／ＥＶＡ、ＥＶＡ／（ＭＬＬ＋ＬＤ）／ＥＶＡ、ＥＶＡ／（ＭＬＬ＋ＶＬ）／ＥＶＡ、ＬＬ／（ＭＬＬ＋ＥＶＡ）／ＥＶＡ、ＥＶＡ／ＭＬＬ／（ＥＶＡ＋ＬＤ）、（ＥＶＡ＋ＬＬ）／ＭＬＬ／（ＥＶＡ＋ＬＬ）、ＥＶＡ／（ＭＬＬ＋ＥＶＡ）／（ＥＶＡ＋ＬＬ）、ＥＥＡ／ＭＬＬ／ＥＥＡ、ＥＥＡ／（ＭＬＬ＋ＬＤ）／ＥＥＡ、ＥＥＡ／（ＭＬＬ＋ＬＬ）／ＥＥＡ、ＥＥＡ／（ＭＬＬ＋ＥＶＡ）／ＥＥＡ、ＥＥＡ／ＭＬＬ／（ＥＶＡ＋ＥＥＡ）等が挙げられる。
【００５２】
本発明においては、前記第Ｉの層、第ＩＩの層、第ＩＩＩの層の樹脂またはその組成物に粘着付与剤を配合することが望ましい。該粘着付与剤としては、ポリブテン、ヒマシ油誘導体、ソルビタン脂肪酸エステル、ロジンおよびロジン誘導体、石油樹脂およびそれらの水添物等のタッキファイヤー、ゴム等が挙げられる。これら粘着付与剤は樹脂または樹脂組成物１００重量部に対して０．１〜２０重量部の範囲で配合することが好ましい。
【００５３】
本発明の特定のエチレン・α−オレフィン共重合体またはその組成物に対して、本発明の特性を本質的に阻害しない範囲で、滑剤、有機あるいは無機フィラー、酸化防止剤、防曇剤、有機あるいは無機系顔料、分散剤、核剤、発泡剤、難燃剤、架橋剤などの公知の添加剤を添加することができる。
これらの添加剤の中でも、滑剤、無機フィラーは作業性をより向上させるために好適に用いられる。また牧草用ストレッチフィルムは紫外線遮断性が要求されるため顔料を配合することが望ましい。
【００５４】
上記滑剤としては、オレイン酸アミド、ステアリン酸アミド、エルカ酸アミド、等の脂肪酸アミド；ステアリン酸モノグリセライド、ステアリン酸ジグリセライド、オレイン酸モノグリセライド、オレイン酸ジグリセライド等の脂肪酸グリセリンエステル化合物およびそれらのポリエチレングリコール付加物等が挙げられる。
【００５５】
また無機フィラーとしては、軽質および重質炭酸カルシウム、タルク、シリカ、ゼオライト、炭酸マグネシウム、長石等が挙げられる。
顔料としてはカーボンブラック、チタン白等の他、市販の各種着色剤マスターバッチが好適に用いられる。
【００５６】
本発明のフィルムの製造方法は、公知のインフレーション成形法、Ｔダイ成形法、水冷フィルム成形法等の成形方法を用い、個々のフィルムを積層してもよいが、好ましくは多層インフレーション成形法、多層Ｔダイ成形法等の共押出成形法が好ましい。
本発明のストレッチフィルムは、パレット包装用ストレッチフィルム、牧草包装用ストレッチフィルム用途等に好適に用いられる。
【００５７】
【実施例】
次に実施例により本発明を更に詳しく説明するが、本発明はこれらによって限定されるものではない。実施例および比較例において使用した樹脂を以下に示すが、本発明のエチレン・α−オレフィン共重合体については次の方法で重合した。
【００５８】
（固体触媒の調製）
窒素下で電磁誘導攪拌機付き触媒調製器（Ｎｏ．１）に精製トルエンを加え、ついでジプロポキシジクロロジルコニウム（Ｚｒ（ＯＰｒ）_２Ｃｌ_２）２８ｇおよびメチルシクロペンタジエン４８ｇを加え、０℃に系を保持しながらトリデシルアルミニウムを４５ｇを滴下し、滴下終了後、反応系を５０℃に保持して１６時間攪拌した。この溶液をＡ液とする。次に窒素下で別の攪拌器付き触媒調製器（Ｎｏ．２）に精製トルエンを加え、前記Ａ溶液と、ついでメチルアルミノキサン６．４ｍｏｌのトルエン溶液を添加し反応させた。これをＢ液とする。
【００５９】
次に窒素下で攪拌器付き調製器（Ｎｏ．１）に精製トルエンを加え、ついであらかじめ４００℃で所定時間焼成処理したシリカ（富士デビソン社製、グレード＃９５２、表面積３００ｍ^２／ｇ）１４００ｇを加えた後、前記Ｂ溶液の全量を添加し、室温で攪拌した。ついで窒素ブローにて溶媒を除去して流動性の良い固体触媒粉末を得た。これを触媒Ｃとする。
【００６０】
（試料の重合）
連続式の流動床気相法重合装置を用い、重合温度７０℃、全圧２０ｋｇｆ／ｃｍ^２Ｇでエチレンと１−ブテンあるいは１−ヘキセンの共重合を行った。前記触媒Ｃを連続的に供給して重合を行ない、系内のガス組成を一定に保つため、各ガスを連続的に供給しながら重合を行った。
【００６１】
（Ａ）：エチレン・α−オレフィン共重合体
Ａ１：エチレン・１−ブテン共重合体
密度＝０．９２０ｇ／ｃｍ³ 、ＭＦＲ＝２．０ｇ／１０ｍｉｎ
分子量分布（Ｍｗ／Ｍｎ）＝２．８
組成分布パラメーターＣｂ＝１．２２
ｄ−０．００８ｌｏｇＭＦＲ＝０．９１７
ＯＤＣＢ可溶分（％）＝３．３＜９．８×１０³ ×（０．９３００−ｄ
＋０．００８１ｏｇＭＦＲ）² ＋２．０
【００６２】
Ａ２：エチレン・１−ヘキセン共重合体
密度＝０．９２１ｇ／ｃｍ³ 、ＭＦＲ＝２．０ｇ／１０ｍｉｎ
分子量分布（Ｍｗ／Ｍｎ）＝２．８
組成分布パラメーターＣｂ＝１．２３
ｄ−０．００８ｌｏｇＭＦＲ＝０．９１９
ＯＤＣＢ可溶分（％）＝３．１＜９．８×１０³ ×（０．９３００−ｄ
＋０．００８１ｏｇＭＦＲ）² ＋２．０
【００６３】
（Ｂ）：エチレン系重合体
Ｂ１１：チーグラー触媒による線状低密度ポリエチレン（ＬＬＤＰＥ）
コモノマー：ブテン−１
密度＝０．９１８ｇ／ｃｍ^３、ＭＦＲ＝２．０ｇ／１０ｍｉｎ
分子量分布（Ｍｗ／Ｍｎ）＝３．７
組成分布パラメーターＣｂ＝１．５３
ｄ−０．００８ｌｏｇＭＦＲ＝０．９１６
ＯＤＣＢ可溶分（％）＝６．３＞９．８×１０^３×（０．９３００−ｄ＋０．００８ｌｏｇＭＦＲ）^２＋２．０
【００６４】
Ｂ１２：チーグラー触媒による超低密度ポリエチレン（ＶＬＤＰＥ）
コモノマー：ブテン−１
密度＝０．９００ｇ／ｃｍ^３、ＭＦＲ＝２．５ｇ／１０ｍｉｎ
分子量分布（Ｍｗ／Ｍｎ）＝４．１
組成分布パラメーターＣｂ＝１．５２
ｄ−０．００８ｌｏｇＭＦＲ＝０．８９７
ＯＤＣＢ可溶分（％）＝３０＞９．８×１０^３×（０．９３００−ｄ＋０．００８ｌｏｇＭＦＲ）^２＋２．０＝１２．８
【００６５】
Ｂ２１：高圧ラジカル重合によるエチレン・酢酸ビニル共重合体（ＥＶＡ）
酢酸ビニル含量＝５重量％、ＭＦＲ＝４．０ｇ／１０ｍｉｎ
Ｂ２２：高圧ラジカル重合による低密度ポリエチレン（ＬＤＰＥ）
密度＝０．９２４ｇ／ｃｍ^３、ＭＦＲ＝４．０ｇ／１０ｍｉｎ
Ｂ２３：高圧ラジカル重合によるエチレン・アクリル酸エチル共重合体（ＥＥＡ）
アクリル酸エチル含量＝１０重量％、ＭＦＲ＝３．０ｇ／１０ｍｉｎ
【００６６】
物性の測定に用いた試験方法は以下の通りである。
（物性試験方法）
密度 ：ＪＩＳ Ｋ６７６０ 準拠
ＭＦＲ ：ＪＩＳ Ｋ６７６０ 準拠
引張強度 ：ＡＳＴＭ Ｄ８８２
引張伸び ：ＡＳＴＭ Ｄ８８２
エルメンドルフ：ＡＳＴＭ Ｄ１９２２
引き裂き強度
ダート衝撃強さ：ＡＳＴＭ Ｄ１７０９
自己粘着性 ：フィルムのＭＤ方向に幅２．５ｃｍ、長さ１２．５ｃｍの試験片を切り取り、長さ方向に二等分し幅２．５ｃｍ、６．２５ｃｍにする。
この二枚組の試験片の端を成形時のフィルムの巻きの外側と内側が接触するよう長さ２．５ｃｍ分重ね合わせる。重ね合わせの部分に７０ｇ／ｃｍ^２の荷重をかけて５分間圧着する。その後、５分以内に引張試験機にかけ（チャック間隔６．３５ｍｍ、引張速度１２５ｍｍ／ｍｉｎ）、引き剥がしに要する力（ｋｇ）を測定する。
【００６７】
結束性（保持応力）：ＡＳＴＭ Ｄ８２２に従って、試料を５００ｍｍ／ｍｉｎで初めの長さの２０％伸長する。
そのまま１６時間放置した後の応力（ｋｇ／ｃｍ^２）を保持力とする。
この保持力が大きいことは、商品等を包装した際ストレッチフィルムによる締め付け力が大であることを示す。
【００６８】
結束性（ストレッチ回復率）：ＡＳＴＭ Ｄ８８２に従って試料を５００ｍｍ／ｍｉｎで２０％伸長する。このままの状態で１６時間放置後、脱荷重し、さらに三日間放置し試料の残留伸長率（Ａ、％）を求め、次式によりストレッチ回復率（％）を求める。
【００６９】

【００７０】
このストレッチ回復率が大きいことは、ストレッチフィルムで包装後、該ストレッチフィルムのたるみが少ないことを示し、結束性があることを示す。
【００７１】
［実施例１〜４］
表１の樹脂構成となるようにして空冷多層インフレーション成形装置を用いて、２層あるいは３層共押出成形し、総厚み３０μｍの積層体を得た。表１にこれらの積層体のフィルム物性を示すがいずれもストレッチフィルムに要求される物性を満足している。
【００７２】
［比較例１］
実施例１のＡ１の替わりに、Ｂ１１のチーグラー触媒による線状低密度ポリエチレンを使用したが、本発明の特定の条件を満足していないため、自己粘着性、ダート衝撃強さ、結束性（保持応力、ストレッチ回復率）の点で不充分な結果となった。
【００７３】
［比較例２］
実施例２のＡ２の替わりに、Ｂ１１のチーグラー触媒による線状低密度ポリエチレンを使用したが、本発明の特定の条件を満足していないため、ダート衝撃強さ、エルメンドルフ引き裂き強度、結束性（保持応力、ストレッチ回復率）の点で不充分な結果となった。
【００７４】
［比較例３］
実施例３のＡ１の替わりに、Ｂ１２のチーグラー触媒による超低密度ポリエチレンを使用したが、本発明の特定の条件を満足していないため、自己粘着性、ダート衝撃強さ、エルメンドルフ引き裂き強度、結束性（保持応力）の点で不充分な結果となった。
【００７５】
［比較例４］
実施例４のＡ２の替わりに、Ｂ１１のチーグラー触媒による線状低密度ポリエチレンを使用したが、本発明の特定の条件を満足していないため、ダート衝撃強さ、引張破断強度、結束性（保持応力、ストレッチ回復率）の点で不充分な結果となった。
【００７６】
【表１】

【００７７】
【表２】

【００７８】
【発明の効果】
本発明は、
【００７９】
特定の条件を満足する密度が０．８６〜０．９４ｇ／ｃｍ ³ 、ＭＦＲ０．１〜５０ｇ／１０分のエチレン・α−オレフィン共重合体を含む第Ｉの層と、（Ｂ）エチレン系重合体とを含む第 II の層との積層体から形成することにより、自己粘着性や耐引き裂き伝播性、突き刺し強度、破断強さ、破断伸び等の機械強度、透明性、延伸性、結束性等に優れたストレッチフィルムを提供するものである。
【図面の簡単な説明】
【図１】本発明の共重合体の溶出温度−溶出量曲線（ＴＲＥＦ曲線）を示す。
【図２】代表的なメタロセン系触媒による共重合体の溶出温度−溶出量曲線（ＴＲＥＦ曲線）を示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stretch film, and more specifically, a self-adhesive property, tear propagation resistance, puncture strength, breaking strength, mechanical strength such as elongation at break, transparency, stretchability, binding property, etc. A stretch film is provided.
[0002]
[Prior art]
2. Description of the Related Art In recent years, pallet stretch packaging, which winds and wraps around a cargo unitized on a pallet while wrapping a film, is widely used in the industry as an energy-saving packaging method. The film for pallet stretch packaging used in these is required to have a self-adhesive property, a large stretch ratio without causing uneven stretching, stretch breakage, etc. during stretch packaging, and strong strength against protrusions. ing.
[0003]
Conventionally, polyethylene resins, ethylene / vinyl acetate copolymer resins, polyvinyl chloride resins and the like are generally used as these pallet stretch films.
Recently, in addition to polyethylene resins and ethylene / vinyl acetate copolymer resins, linear chains made of ethylene / α-olefin copolymers have excellent mechanical strength, transparency, stretchability, adhesiveness, and the like. A low-density polyethylene (LLDPE) alone or a mixture with an ethylene / vinyl acetate copolymer and a laminate (Japanese Patent Publication No. 2-18983, Japanese Utility Model Publication No. 56-74737, etc.) are rapidly spreading.
[0004]
As another application, forage is prepared by wrapping pasted grass in a roll shape with a stretch film and fermenting it. The stretch film for grass needs to maintain high airtightness for a long time outdoors, so the toughness, sufficient stretchability, cohesive strength, elasticity, self-adhesiveness, etc. not to be broken by the projections on the pressed grass surface The same characteristics as a stretch film are required.
In recent years, more advanced films are required from the viewpoint of labor saving of stretch film, simplification of workability, etc., especially the performance of the LLDPE film, that is, self-adhesiveness, tear propagation resistance, puncture strength, breaking strength. Further improvements in mechanical strength such as elongation at break, transparency, stretchability, and binding properties are desired.
[0005]
[Problems to be solved by the invention]
The present invention has been made as a result of intensive studies in view of the above-mentioned problems. The density satisfying specific conditions is 0.86 to 0.94 g / cm ³ , and the melt flow rate (MFR) is 0.1 to 50 g / 10 minutes of (A) a layer I containing an ethylene / α-olefin copolymer and (B) a layer II comprising another ethylene copolymer, The present invention provides a stretch film excellent in mechanical strength such as tear propagation resistance, puncture strength, breaking strength, elongation at break, transparency, stretchability, binding property and the like.
[0006]
[Means for Solving the Problems]
The present invention has (a) a density of 0.86 to 0.94 g / cm ³ , (a) a melt flow rate (MFR) of 0.1 to 50 g / 10 minutes, and (c) a molecular weight distribution (Mw / Mn) of 1. .8 to 3.5, (d) composition distribution parameter Cb is 1.10 to 2.00, (e) the amount X (wt%) of orthodichlorobenzene (ODCB) soluble component at 25 ° C., density d and MFR ( Melt flow rate) satisfies the following relationship: a) When density d and MFR value is d−0.008 log MFR ≧ 0.93, X <2.0
b) When the values of density d and MFR are d−0.008 log MFR <0.93, X <9.8 × 10 ³ (0.9300−d + 0.008 log MFR) ² +2.0
(F) A first I comprising an ethylene / α-olefin copolymer satisfying the above (a) to (f), wherein a plurality of elution temperature-elution amount curve peaks by continuous temperature rising elution fractionation method (TREF) exist. Layers,
(B1) an ethylene-α-olefin copolymer having a density of 0.86 to 0.94 g / cm ³ by a Ziegler type catalyst,
(B2) Stretch film composed of a laminate including at least one ethylene (co) polymer (B) second layer composed of ethylene-based polymer by high-pressure radical polymerization, or both surfaces of the first layer (B1) an ethylene-α-olefin copolymer having a density of 0.86 to 0.94 g / cm ³ by a Ziegler catalyst type catalyst, (B2) at least one of (B) an ethylene (co) polymer by high-pressure radical polymerization The present invention provides a stretch film made of a laminated layer having a layer II and a layer III made of an ethylene polymer.
[0007]
In another invention, adhesion is improved to 100 parts by weight of the resin or resin composition constituting the first layer, the second layer and / or the third layer according to any one of claims 1 to 3 in which the adhesiveness is improved. The stretch film formed by blending 0.1 to 20 parts by weight of the imparting agent is provided.
[0008]
The present invention will be described in detail below.
The ethylene / α-olefin copolymer satisfying the following (a) to (f) used in the present invention is a copolymer of ethylene and one or more selected from α-olefins having 3 to 20 carbon atoms. is there. The α-olefin having 3 to 20 carbon atoms is preferably one having 3 to 12 carbon atoms, specifically, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene. , 1-decene, 1-dodecene, and the like. Further, the total content of these α-olefins is usually 30 mol% or less, preferably 20 mol%.
[0009]
[A-ka]
(A) Density is 0.86-0.94 g / cm ³
(A) Melt flow rate (MFR) 0.1-50 g / 10 min (U) Molecular weight distribution (Mw / Mn) 1.8-3.5
(D) The composition distribution parameter Cb is 1.10 to 2.00
(E) The amount X (wt%) of the orthodichlorobenzene (ODCB) soluble component at 25 ° C. and the density d and MFR (melt flow rate) satisfy the following relationship: a) The values of density d and MFR are d-0. .008 log MFR ≧ 0.93 X <2.0
b) When the values of density d and MFR are d−0.008 log MFR <0.93, X <9.8 × 10 ³ (0.9300−d + 0.008 log MFR) ² +2.0
(F) There are a plurality of peaks of the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF).
The (A) density of the (A) ethylene / α-olefin copolymer of the present invention is 0.86 to 0.94 g / cm ³ , preferably 0.88 to 0.93 g / cm ³ , more preferably 0.8. It is in the range of 89 to 0.925 g / cm ³ . If the density is less than 0.86 g / cm ³ , there may be a problem in stretchability and bundling property, and if it exceeds 0.94 g / cm ³ , a problem in adhesiveness will occur.
[0011]
The (A) MFR of the (A) ethylene / α-olefin copolymer of the present invention is 0.1 to 50 g / 10 min, preferably 0.2 to 30 g / 10 min, more preferably 0.3 to 20 g / min. 10 minutes. When the MFR is less than 0.1 g / 10 min, the molding processability is inferior, and when it exceeds 50 g / 10 min, the mechanical strength and the binding property are inferior.
[0012]
The Mw / Mn of the ethylene / α-olefin copolymer (U) of the present invention is 1.8 to 3.5, preferably 2.0 to 3.0, more preferably 2.2 to 2. It is desirable to be in the range of .8. When Mw / Mn is less than 1.8, molding processability is inferior, and when it exceeds 3.5, impact resistance is inferior.
The molecular weight distribution (Mw / Mn) is calculated by obtaining a weight average molecular weight (Mw) and a number average molecular weight (Mn) by gel permeation chromatography (GPC), and obtaining this ratio Mw / Mn.
[0013]
The (A) composition distribution parameter Cb of the (A) ethylene / α-olefin copolymer of the present invention is 1.10 to 2.00, preferably 1.12 to 1.70, more preferably 1.15. It is desirable to be in the range of 1.50.
If it is greater than 2.00, blocking tends to occur, heat sealing properties are poor, and low molecular weight or highly branched components ooze out to the resin surface, causing sanitary problems.
[0014]
The method for measuring the composition distribution parameter Cb of the ethylene / α-olefin copolymer is as follows.
That is, it is heated and dissolved at 135 ° C. in orthodichlorobenzene (ODCB) to which an antioxidant is added so that the sample concentration becomes 0.2% by weight. This solution is transferred to a column packed with diatomaceous earth (Celite 545), cooled to 25 ° C. at a rate of 0.1 ° C./min, and the sample is deposited on the celite surface. Next, while flowing ODCB through this column at a constant flow rate, the column temperature is raised stepwise to 120 ° C. in steps of 5 ° C., and the sample is eluted and fractionated. Methanol is mixed with the eluate, and after reprecipitation, the sample is filtered and dried to obtain a fraction sample at each elution temperature. The weight fraction of the eluted sample at each temperature and the degree of branching (the number of branches per 1000 carbon atoms) are measured by 13C-NMR.
[0015]
For the fraction from 30 ° C. to 90 ° C., the branching degree is corrected as follows. That is, the degree of branching measured against the elution temperature is plotted, the correlation is approximated to a straight line by the method of least squares, and a calibration curve is created. This approximate correlation coefficient is sufficiently large. The value obtained from this calibration curve is taken as the degree of branching of each fraction. For components having an elution temperature of 95 ° C. or higher, a linear relationship is not necessarily established between the elution temperature and the degree of branching, and thus this correction is not performed and measured values are used.
[0016]
Then the weight fraction wi of each fraction to obtain the relative concentration c _i divided by the amount of change in the degree of branching b _i per the elution temperature _{5 ℃ (b i -b i-} 1), relative with respect to the degree of branching The concentration is plotted and a composition distribution curve is obtained. This composition distribution curve is divided by a certain width, and the composition distribution parameter Cb is calculated from the following equation.
[0017]
[Expression 1]

[0018]
Here, c _j and b _j are the relative density and the branching degree of the j-th section, respectively. The composition distribution parameter Cb is 1.0 when the composition of the sample is uniform, and increases as the composition distribution increases.
[0019]
Many methods have been proposed for describing the composition distribution of an ethylene / α-olefin copolymer. For example, in Japanese Patent Laid-Open No. 60-88016, numerical processing is performed on the assumption that the cumulative weight fraction has a specific distribution (logarithmic normal distribution) with respect to the number of branches of each fractionated sample obtained by solvent fractionation of the sample. The ratio of the weight average branching degree (Cw) and the number average branching degree (Cn) is obtained. The approximation calculation accuracy is lowered when the number of branches and cumulative weight fraction of the sample deviate from the logarithmic normal distribution, correlation coefficient R ² to perform measurements on commercially available LLDPE is fairly low, the accuracy of the values is not sufficient. The Cw / Cn measurement method and numerical processing method are different from those of Cb of the present invention. However, if numerical comparison is made, the value of Cw / Cn is considerably larger than Cb.
[0020]
The amount of the ODCB soluble component at 25 ° C. of the ethylene / α-olefin copolymer of the present invention is measured by the following method.
A sample of 0.5 g is heated with 20 ml of ODCB at 135 ° C. for 2 hours to completely dissolve the sample, and then cooled to 25 ° C. The solution is allowed to stand at 25 ° C. overnight and then filtered through a Teflon filter to collect the filtrate. The absorption peak area in the vicinity of the wave number of 2925 cm ⁻¹ of the asymmetric stretching vibration of methylene in the filtrate is obtained, and the sample concentration is calculated using a calibration curve prepared in advance. From this value, the ODCB soluble content at 25 ° C. is determined.
[0021]
The relationship between the amount of ODCB soluble matter at 25 ° C., X wt% of the present invention, and the density d and MFR is as follows when the values of d and MFR satisfy d−0.008log MFR ≧ 0.93:
X is less than 2% by weight, preferably less than 1% by weight. When d−0.008log MFR <0.93, X <9.8 × 10 ³ × (0.9300−d + 0.008 log MFR) ² +2.0
Preferably,
X <7.4 × 10 ³ × (0.9300-d + 0.008logMFR) ² +1.0
More preferably,
X <5.6 × 10 ³ × (0.9300−d + 0.008logMFR) ² +0.5
It is necessary to satisfy the relationship.
[0022]
The ODCB soluble content at 25 ° C. is a high branching component and a low molecular weight component contained in the ethylene / α-olefin copolymer, which causes sanitary problems and blocking of the inner surface of the molded product. Less is desirable. The amount of ODCB solubles is affected by comonomer content and molecular weight. Therefore, the fact that the density and the amount of soluble components of MFR and ODCB satisfy the above relationship indicates that there is little uneven distribution of α-olefins contained in the entire copolymer.
[0023]
The (A) ethylene / α-olefin copolymer of the present invention needs to have a plurality of peaks in the elution temperature-elution amount curve obtained by (f) continuous temperature rising elution fractionation (TREF). . Further, it is particularly preferable that a peak exists between 85 ° C. and 100 ° C. The presence of this peak improves the heat resistance of the molded body. FIG. 1 shows an elution temperature-elution amount curve of the copolymer of the present invention, and FIG. 2 shows a difference from a copolymer using a so-called metallocene catalyst.
[0024]
The method for measuring TREF according to the present invention is as follows. The sample is heated and dissolved at 135 ° C. in ODCB to which an antioxidant is added so that the sample concentration becomes 0.05% by weight. 5 ml of this sample solution is injected into a column filled with glass beads, cooled to 25 ° C. at a cooling rate of 0.1 ° C./min, and the sample is deposited on the surface of the glass beads. Next, the sample is sequentially eluted while increasing the column temperature at a constant rate of 50 ° C./hr while allowing ODCB to flow through the column at a constant flow rate. At this time, the concentration of the sample eluted in the solvent is continuously detected by the infrared detector with respect to the absorption of wave number 2925 cm ⁻¹ of the asymmetric stretching vibration of methylene. From this value, the concentration of the ethylene / α-olefin copolymer in the solution is quantitatively analyzed to determine the relationship between the elution temperature and the elution rate. TREF analysis is a very small amount of sample, and since it is possible to continuously analyze changes in elution rate with respect to temperature changes, relatively fine peaks that cannot be detected by a fractionation method can be detected.
[0025]
The production of the specific ethylene / α-olefin copolymer of the present invention is preferably carried out by polymerization using the following catalyst comprising C1 to C5.
That, C1: the general formula ^{_{Me 1 R 1 p (OR 2}} ) q X 1 4-p-q compounds represented by (wherein Me ¹ represents zirconium, titanium, hafnium, ^{R 1} and ^{R 2} are each carbon A hydrocarbon group of formulas 1 to 24, X ¹ represents a halogen atom, and p and q are integers satisfying the ranges of 0 ≦ p <4 and 0 ≦ p + q ≦ 4), C2: General formula Me ² R Compound represented by ³ _m (OR ⁴ ) _n X ² _zm-n (wherein Me ² is a Group I to III element in the periodic table, and R ³ and R ⁴ are each a hydrocarbon having 1 to 24 carbon atoms) Group, X ² represents a halogen atom or a hydrogen atom (however, when X ² is a hydrogen atom, Me ² is limited to a group III element in the periodic table), z represents a valence of Me ² , m And n are integers satisfying the ranges 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively, and 0 m + n ≦ z), C3: an organic cyclic compound having a conjugated double bond, and C4: a modified organoaluminum compound containing an Al—O—Al bond obtained by reaction of an organoaluminum compound with water, C5: an inorganic carrier And / or a catalyst obtained by bringing particulate polymer carriers into contact with each other.
[0026]
Formula ^{_{Me 1 R 1 p (OR 2}} ) wherein Me ¹ of _{^q X 1 ^4-p-q} compounds represented by the above catalyst component C1 represents zirconium, titanium, hafnium. The type of these transition metals is not limited, and a plurality of transition metals can be used, but it is particularly preferable that zirconium having excellent weather resistance of the copolymer is included. R ¹ and R ² are each a hydrocarbon group having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, specifically a methyl group, an ethyl group, a propyl group, an isopropyl group. Alkyl group such as butyl group; alkenyl group such as vinyl group and allyl group; aryl group such as phenyl group, tolyl group, xylyl group, mesityl group, indenyl group and naphthyl group; benzyl group, trityl group, phenethyl group and styryl Aralkyl groups such as a group, a benzhydryl group, a phenylbutyl group, and a neofoyl group. These may be branched. X ¹ represents a halogen atom such as fluorine, iodine, chlorine and bromine, and p and q satisfy the ranges of 0 ≦ p <4, 0 ≦ q <4 and 0 ≦ p + q ≦ 4, respectively, preferably 0 ≦ p + q ≦ 4 range.
[0027]
Examples of the compound represented by the general formula of the catalyst component C1 include tetramethylzirconium, tetraethylzirconium, tetrabenzylzirconium, tetrapropoxyzirconium, tripropoxymonochlorozirconium, tetrabutoxyzirconium, tetrabutoxytitanium, tetrabutoxyhafnium and the like. In particular, Zr (OR) ₄ compounds such as tetrapropoxyzirconium and tetrabutoxyzirconium, and two or more of these may be used in combination.
[0028]
The general formula ^{_{Me 2 R 3 m (OR 4}} ) of the catalyst component C2 ⁿ _{X 2} wherein Me ² in the compound represented by the _z-m-n represents the periodic table I~III group element, lithium, sodium Potassium, magnesium, calcium, zinc, boron, aluminum and the like. R ³ and R ⁴ are each a hydrocarbon group having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl Alkyl groups such as vinyl groups; alkenyl groups such as vinyl groups and allyl groups; aryl groups such as phenyl groups, tolyl groups, xylyl groups, mesityl groups, indenyl groups, and naphthyl groups; benzyl groups, trityl groups, phenethyl groups, styryl groups, Examples thereof include aralkyl groups such as benzhydryl group, phenylbutyl group, and neofoyl group. These may be branched. X ² represents a halogen atom or a hydrogen atom such as fluorine, iodine, chlorine and bromine. However, when X ² is a hydrogen atom, Me ² is limited to a group III element of the periodic table exemplified by boron, aluminum and the like. Z represents the valence of Me ² , and m and n are integers satisfying the ranges of 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively, and 0 ≦ m + n ≦ z.
[0029]
Examples of the compound represented by the general formula of the catalyst component C2 include organic lithium compounds such as methyl lithium and ethyl lithium; organomagnesium compounds such as dimethyl magnesium, diethyl magnesium, methyl magnesium chloride, and ethyl magnesium chloride; dimethyl zinc and diethyl Organic zinc compounds such as zinc; organic boron compounds such as trimethylboron and triethylboron; trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tridecylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, diethyl Organic aluminum compounds such as aluminum ethoxide and diethylaluminum hydride Derivatives and the like.
[0030]
The organic cyclic compound having a conjugated double bond of the catalyst component C3 is one or two rings that are cyclic and have 2 or more, preferably 2 to 4, more preferably 2 to 3 conjugated double bonds. As described above, a cyclic hydrocarbon compound having 4 to 24, preferably 4 to 12 carbon atoms in total; the cyclic hydrocarbon compound is partially composed of 1 to 6 hydrocarbon residues (typically having 1 carbon atom) A cyclic hydrocarbon compound substituted with ˜12 alkyl groups or aralkyl groups; one or more rings having 2 or more, preferably 2 to 4, more preferably 2 to 3 conjugated double bonds And an organosilicon compound having a cyclic hydrocarbon group having 4 to 24 carbon atoms, preferably 4 to 12 carbon atoms; a hydrocarbon residue or alkali metal salt partially having 1 to 6 cyclic hydrocarbon groups ( Sodium or lithium salt) The organosilicon compound contains. Particularly preferred is one having a cyclopentadiene structure in any of the molecules.
[0031]
Suitable examples of the compound include cyclopentadiene, indene, azulene or alkyl, aryl, aralkyl, alkoxy or aryloxy derivatives thereof. Moreover, the compound which these compounds couple | bonded (bridge | crosslinked) through the alkylene group (The carbon number is 2-8 normally, Preferably 2-3) is also used suitably.
[0032]
The organosilicon compound having a cyclic hydrocarbon group can be represented by the following general formula.
A _L SiR _4-L
Here, A represents the cyclic hydrogen group exemplified by cyclopentadienyl group, substituted cyclopentadienyl group, indenyl group, and substituted indenyl group, and R represents methyl group, ethyl group, propyl group, isopropyl group, butyl group An alkyl group such as a group; an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group; an aryl group such as a phenyl group; an aryloxy group such as a phenoxy group; an aralkyl group such as a benzyl group; To 24, preferably 1 to 12 hydrocarbon residues or hydrogen, L is 1 ≦ L ≦ 4, preferably 1 ≦ L ≦ 3.
[0033]
Specific examples of the organic cyclic hydrocarbon compound of the component C3 include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, 1,3-dimethylcyclopentadiene, indene, 4-methyl-1-indene, 4,7-dimethylindene, Cyclopolyene having 5 to 24 carbon atoms such as cycloheptatriene, methylcycloheptatriene, cyclooctatetraene, azulene, fluorene, methylfluorene or substituted cyclopolyene, monocyclopentadienylsilane, biscyclopentadienylsilane, Examples include triscyclopentadienylsilane, monoindenylsilane, bisindenylsilane, and trisindenylsilane.
[0034]
The modified organoaluminum compound containing an Al—O—Al bond obtained by the reaction between the organoaluminum compound of the catalyst component C4 and water is a modified organic usually called aluminoxane by reacting an alkylaluminum compound with water. Aluminum is obtained and usually contains 1 to 100, preferably 1 to 50, Al—O—Al bonds in the molecule. The modified organoaluminum compound may be linear or cyclic.
[0035]
The reaction between organoaluminum and water is usually carried out in an inert hydrocarbon. As the inert hydrocarbon, aliphatic, alicyclic and aromatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, benzene, toluene and xylene are preferable.
The reaction ratio (water / Al molar ratio) between water and the organoaluminum compound is usually 0.25 / 1 to 1.2 / 1, preferably 0.5 / 1 to 1/1.
[0036]
Examples of the inorganic carrier and / or particulate polymer carrier of the catalyst component C5 include carbonaceous materials, metals, metal oxides, metal chlorides, metal carbonates, or mixtures thereof, thermoplastic resin, thermosetting resin, and the like. . Suitable metals that can be used for the inorganic carrier include iron, aluminum, nickel and the like.
Specifically, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO _2, etc. or a mixture thereof can be mentioned, and SiO ₂ —Al ₂ O ₃ , Examples thereof include SiO ₂ —V ₂ O ₅ , SiO ₂ —TiO ₂ , SiO ₂ —V ₂ O ₅ , SiO ₂ —MgO, and SiO ₂ —Cr ₂ O ₃ . Among these, those having as a main component at least one component selected from the group consisting of SiO ₂ and Al ₂ O ₃ are preferable.
[0037]
As the organic compound, any of a thermoplastic resin and a thermosetting resin can be used. Specifically, particulate polyolefin, polyester, polyamide, polyvinyl chloride, poly (meth) acrylate, polystyrene, Examples include norbornene, various natural polymers, and mixtures thereof.
The inorganic carrier and / or the particulate polymer carrier can be used as they are, but preferably, as a pretreatment, these carriers are contacted with an organoaluminum compound or a modified organoaluminum compound containing an Al—O—Al bond. After that, it can also be used as component C5.
[0038]
The method for producing the ethylene / α-olefin copolymer of the present invention is produced by a gas phase method, a slurry method, a solution method or the like, and is not particularly limited, such as a one-stage polymerization method or a multi-stage polymerization method.
[0039]
The other (B) ethylene polymer of the present invention is ethylene having a density of 0.86 to 0.94 g / cm ³ by (B1) high, medium and low pressure methods using a Ziegler type catalyst and other known methods. And an α-olefin having 3 to 20 carbon atoms and / or (B2) an ethylene-based (co) polymer obtained by a high-pressure radical polymerization method.
[0040]
(B1) Copolymerization of ethylene having a density of 0.86 to 0.94 g / cm ³ and an α-olefin having 3 to 20 carbon atoms by the above-described high, medium and low pressure methods using a Ziegler type catalyst or the like and other known methods. the polymer density (hereinafter referred to as LLDPE) linear low density polyethylene 0.91~0.94g / cm ^3, very low density polyethylene having a density of 0.86~0.91g / cm ³ (hereinafter VLDPE And ethylene / α-olefin copolymer rubber such as ethylene / propylene copolymer rubber and ethylene / propylene / diene copolymer rubber having a density of 0.86 to 0.91 g / cm ³ .
[0041]
The LLDPE by the Ziegler type catalyst is an ethylene / α-olefin copolymer having a density in the range of 0.91 to 0.94 g / cm ³ , preferably 0.91 to 0.93 g / cm ^3. The olefin has 3 to 20 carbon atoms, preferably 4 to 12 carbon atoms, and specifically includes propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Can be mentioned.
[0042]
The Ziegler-type catalyst very low density polyethylene (VLDPE) is an ethylene-α-olefin copolymer having a density of 0.86 to 0.91 g / cm ³ , preferably 0.88 to 0.905 g / cm ^3. It is a polymer and a polyethylene having intermediate properties between linear low density polyethylene (LLDPE) and ethylene / α-olefin copolymer rubber (EPR, EPDM).
[0043]
Examples of the ethylene / α-olefin copolymer rubber include ethylene / propylene copolymer rubber having a density of less than 0.86 to less than 0.91 g / cm ³ , ethylene / propylene / diene copolymer rubber, and the like. The ethylene / propylene rubber is mainly composed of a random copolymer (EPM) containing ethylene and propylene as main components and a diene monomer (dicyclopentadiene, ethylidene norbornene, etc.) added as a third component. A random copolymer (EPDM) is mentioned.
[0044]
The ethylene (co) polymer obtained by the high-pressure radical polymerization is an ethylene homopolymer (low-density polyethylene), an ethylene / vinyl ester copolymer, ethylene and an α, β-unsaturated carboxylic acid or its derivative obtained by high-pressure radical polymerization. And the like.
[0045]
The low density polyethylene is produced by a known high pressure radical polymerization method, and may be either a tubular method or an autoclave method.
[0046]
The ethylene-vinyl ester copolymer is produced by a high-pressure radical polymerization method, mainly composed of ethylene, vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl stearate, trifluoroacetic acid. It is a copolymer with a vinyl ester monomer such as hinyl. Among these, vinyl acetate is particularly preferable. A copolymer comprising 50 to 99.5% by weight of ethylene and 0.5 to 50% by weight of vinyl ester is preferable. Furthermore, the vinyl ester content is preferably selected in the range of 3 to 20% by weight, particularly preferably 5 to 15% by weight.
[0047]
Further, typical copolymers of ethylene and α, β-unsaturated carboxylic acid or derivatives thereof include ethylene / (meth) acrylic acid or alkyl ester copolymers thereof. As comonomer, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, acrylic acid-n-butyl, methacrylic acid Examples include acid-n-butyl, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, glycidyl acrylate, and glycidyl methacrylate. Among these, alkyl esters such as methyl and ethyl of (meth) acrylic acid are particularly preferable. In particular, the (meth) acrylic acid ester content is in the range of 3 to 20% by weight, preferably 5 to 15% by weight.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
One of the embodiments of the stretch film having a laminated structure of the present invention is as follows: (A) a first layer containing an ethylene-α-olefin copolymer and (B) a second layer comprising an ethylene-based copolymer It is a stretch film which consists of a laminated body of at least 2 layers.
The first layer is a composition layer of the specific (A) ethylene-α-olefin copolymer alone or the specific (A) ethylene-α-olefin copolymer and (B) an ethylene-based polymer. It may be formed. The composition of the above specific (A) ethylene-α-olefin copolymer and (B) ethylene polymer has a balance of molding stability, transparency, mechanical strength, adhesiveness, stretchability, binding property, and the like. (A) 98-20% by weight, (B) 2-80% by weight, preferably (A) 90-50% by weight, (B) 10-50% by weight, more preferably (A) It is selected in the range of 80 to 60% by weight and (B) 20 to 40% by weight. In the second layer, (B1) an ethylene-α-olefin copolymer having a density of 0.86 to 0.94 g / cm ³ by a Ziegler catalyst or (B2) an ethylene (co) polymer by high-pressure radical polymerization is used. You may use individually or as a mixed composition.
[0049]
Specific combinations of these include MLL / EVA, (MLL + LD) / EVA, (MLL + LL) / EVA, (MLL + EVA) / EVA, MLL / (EVA + LD), MLL / (EVA + LL), (MLL + EVA) / (EVA + L) , MLL / EEA, (MLL + LD) / EEA, (MLL + VL) / EEA, (MLL + EVA) / EEA, MLL / (EVA + EEA), and the like.
(However, MLL: (A) ethylene-α-olefin copolymer of the present invention, EVA: ethylene-vinyl acetate copolymer, LD: high-pressure radical method low-density polyethylene, LL: linear low-density polyethylene, VL: super (Low density polyethylene, EEA: ethylene-ethyl acrylate copolymer)
[0050]
Another aspect of the stretch film having the laminated structure of the present invention is that an ethylene-α-olefin copolymer having a density of 0.86 to 0.94 g / cm ³ by (B1) Ziegler type catalyst on both sides of the first layer. Or (B2) a stretch film comprising a laminate provided with a second layer and a third layer made of at least one (B) ethylene-based polymer of ethylene (co) polymer by high-pressure radical polymerization, The I layer, the II layer, and the III layer may be formed of the same type or different types and a mixture layer.
[0051]
Specific examples of these combinations include EVA / MLL / EVA, EVA / (MLL + LD) / EVA, EVA / (MLL + VL) / EVA, LL / (MLL + EVA) / EVA, EVA / MLL / (EVA + LD), (EVA + LL) / MLL / (EVA + LL), EVA / (MLL + EVA) / (EVA + LL), EEA / MLL / EEA, EEA / (MLL + LD) / EEA, EEA / (MLL + LL) / EEA, EEA / (MLE / MLA / L, EVA) / (EVA + EEA) and the like.
[0052]
In the present invention, it is desirable to add a tackifier to the resin of the first layer, the second layer, the third layer or the composition thereof. Examples of the tackifier include tackifiers such as polybutene, castor oil derivatives, sorbitan fatty acid esters, rosin and rosin derivatives, petroleum resins and hydrogenated products thereof, and rubbers. These tackifiers are preferably blended in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin or resin composition.
[0053]
To the specific ethylene / α-olefin copolymer or composition thereof of the present invention, a lubricant, organic or inorganic filler, antioxidant, antifogging agent, Or well-known additives, such as an inorganic pigment, a dispersing agent, a nucleating agent, a foaming agent, a flame retardant, and a crosslinking agent, can be added.
Among these additives, a lubricant and an inorganic filler are preferably used in order to further improve workability. Moreover, since the grass stretch film is required to have ultraviolet blocking properties, it is desirable to incorporate a pigment.
[0054]
Examples of the lubricant include fatty acid amides such as oleic acid amide, stearic acid amide, and erucic acid amide; fatty acid glycerin ester compounds such as stearic acid monoglyceride, stearic acid diglyceride, oleic acid monoglyceride, and oleic acid diglyceride; and their polyethylene glycol adducts Etc.
[0055]
Examples of the inorganic filler include light and heavy calcium carbonate, talc, silica, zeolite, magnesium carbonate, feldspar and the like.
As the pigment, carbon black, titanium white and the like, and various commercially available colorant masterbatches are preferably used.
[0056]
The method for producing the film of the present invention may be a method of laminating individual films using a known inflation molding method, a T-die molding method, a water-cooled film molding method, or the like, but preferably a multilayer inflation molding method, a multilayer A coextrusion molding method such as a T-die molding method is preferred.
The stretch film of the present invention is suitably used for pallet packaging stretch films, pasture packaging stretch films, and the like.
[0057]
【Example】
EXAMPLES Next, although an Example demonstrates this invention in more detail, this invention is not limited by these. The resins used in Examples and Comparative Examples are shown below. The ethylene / α-olefin copolymer of the present invention was polymerized by the following method.
[0058]
(Preparation of solid catalyst)
Purified toluene was added to a catalyst preparation apparatus (No. 1) equipped with an electromagnetic induction stirrer under nitrogen, and then 28 g of dipropoxydichlorozirconium (Zr (OPr) ₂ Cl ₂ ) and 48 g of methylcyclopentadiene were added, and the system was maintained at 0 ° C. While dropping 45 g of tridecylaluminum, the reaction system was kept at 50 ° C. and stirred for 16 hours. Let this solution be A liquid. Next, purified toluene was added to another catalyst preparation device with a stirrer (No. 2) under nitrogen, and the solution A and then a toluene solution of 6.4 mol of methylaluminoxane were added and reacted. This is B liquid.
[0059]
Next, purified toluene was added to a preparation device with a stirrer under nitrogen (No. 1), and then 1400 g of silica (manufactured by Fuji Devison, grade # 952, surface area 300 m ² / g) previously calcined at 400 ° C. for a predetermined time was added. After the addition, the entire amount of the solution B was added and stirred at room temperature. Subsequently, the solvent was removed by nitrogen blowing to obtain a solid catalyst powder having good fluidity. This is referred to as catalyst C.
[0060]
(Sample polymerization)
Using a continuous fluidized bed gas phase polymerization apparatus, ethylene and 1-butene or 1-hexene were copolymerized at a polymerization temperature of 70 ° C. and a total pressure of 20 kgf / cm ² G. Polymerization was carried out by continuously supplying the catalyst C, and the polymerization was carried out while continuously supplying each gas in order to keep the gas composition in the system constant.
[0061]
(A): Ethylene / α-olefin copolymer A1: Ethylene / 1-butene copolymer Density = 0.920 g / cm ³ , MFR = 2.0 g / 10 min
Molecular weight distribution (Mw / Mn) = 2.8
Composition distribution parameter Cb = 1.22
d-0.008log MFR = 0.717
ODCB soluble content (%) = 3.3 <9.8 × 10 ³ × (0.9300-d
+0.0081 og MFR) ² +2.0
[0062]
A2: Ethylene / 1-hexene copolymer Density = 0.721 g / cm ³ , MFR = 2.0 g / 10 min
Molecular weight distribution (Mw / Mn) = 2.8
Composition distribution parameter Cb = 1.23
d-0.008log MFR = 0.919
ODCB soluble content (%) = 3.1 <9.8 × 10 ³ × (0.9300-d
+0.0081 og MFR) ² +2.0
[0063]
(B): Ethylene polymer B11: Linear low density polyethylene (LLDPE) with Ziegler catalyst
Comonomer: Butene-1
Density = 0.918 g / cm ³ , MFR = 2.0 g / 10 min
Molecular weight distribution (Mw / Mn) = 3.7
Composition distribution parameter Cb = 1.53
d-0.008log MFR = 0.916
ODCB soluble content (%) = 6.3> 9.8 × 10 ³ × (0.9300−d + 0.008log MFR) ² +2.0
[0064]
B12: Very low density polyethylene (VLDPE) with Ziegler catalyst
Comonomer: Butene-1
Density = 0.000 g / cm ³ , MFR = 2.5 g / 10 min
Molecular weight distribution (Mw / Mn) = 4.1
Composition distribution parameter Cb = 1.52
d-0.008log MFR = 0.897
ODCB soluble content (%) = 30> 9.8 × 10 ³ × (0.9300−d + 0.008 log MFR) ² + 2.0 = 12.8
[0065]
B21: Ethylene / vinyl acetate copolymer (EVA) by high-pressure radical polymerization
Vinyl acetate content = 5% by weight, MFR = 4.0 g / 10 min
B22: Low density polyethylene (LDPE) by high pressure radical polymerization
Density = 0.924 g / cm ³ , MFR = 4.0 g / 10 min
B23: Ethylene / ethyl acrylate copolymer (EEA) by high-pressure radical polymerization
Ethyl acrylate content = 10% by weight, MFR = 3.0 g / 10 min
[0066]
The test methods used for measuring the physical properties are as follows.
(Physical property test method)
Density: JIS K6760 compliant MFR: JIS K6760 compliant tensile strength: ASTM D882
Tensile elongation: ASTM D882
Elmendorf: ASTM D1922
Tear strength Dirt impact strength: ASTM D1709
Self-adhesiveness: A test piece having a width of 2.5 cm and a length of 12.5 cm is cut in the MD direction of the film, and is bisected in the length direction to have a width of 2.5 cm and 6.25 cm.
The ends of the two-piece test pieces are overlapped by a length of 2.5 cm so that the outer side and the inner side of the film winding at the time of molding are in contact with each other. A pressure of 70 g / cm ² is applied to the overlapped portion for 5 minutes. Thereafter, it is applied to a tensile tester within 5 minutes (chuck interval 6.35 mm, tensile speed 125 mm / min), and the force (kg) required for peeling is measured.
[0067]
Cohesiveness (holding stress): according to ASTM D822, the sample is stretched 20% of the original length at 500 mm / min.
The stress (kg / cm ² ) after leaving as it is for 16 hours is taken as the holding force.
A large holding force indicates that the tightening force by the stretch film is large when a product or the like is packaged.
[0068]
Cohesiveness (stretch recovery rate): The sample is stretched 20% at 500 mm / min according to ASTM D882. In this state, the sample is allowed to stand for 16 hours, then unloaded, and further left for three days to obtain the residual elongation rate (A,%) of the sample, and the stretch recovery rate (%) is obtained from the following equation.
[0069]

[0070]
A large stretch recovery rate indicates that there is little sagging of the stretch film after packaging with the stretch film, indicating that there is a binding property.
[0071]
[Examples 1 to 4]
Two-layer or three-layer coextrusion molding was performed using an air-cooled multilayer inflation molding apparatus so as to have the resin configuration shown in Table 1 to obtain a laminate having a total thickness of 30 μm. Table 1 shows the film physical properties of these laminates, but all satisfy the physical properties required for stretch films.
[0072]
[Comparative Example 1]
Instead of A1 in Example 1, linear low-density polyethylene with B11 Ziegler catalyst was used, but because it did not satisfy the specific conditions of the present invention, self-adhesion, dirt impact strength, cohesiveness (retention) The results are insufficient in terms of stress and stretch recovery rate.
[0073]
[Comparative Example 2]
In place of A2 in Example 2, linear low density polyethylene with Ziegler catalyst of B11 was used, but because it did not satisfy the specific conditions of the present invention, Dart impact strength, Elmendorf tear strength, cohesiveness (retention) The results are insufficient in terms of stress and stretch recovery rate.
[0074]
[Comparative Example 3]
Instead of A1 in Example 3, B12 Ziegler-catalyzed ultra-low density polyethylene was used, but because it did not satisfy the specific conditions of the present invention, self-adhesion, Dart impact strength, Elmendorf tear strength, binding The results were insufficient in terms of properties (holding stress).
[0075]
[Comparative Example 4]
Instead of A2 in Example 4, linear low-density polyethylene with a Ziegler catalyst of B11 was used, but because it did not satisfy the specific conditions of the present invention, the dart impact strength, tensile breaking strength, binding property (retention) The results are insufficient in terms of stress and stretch recovery rate.
[0076]
[Table 1]

[0077]
[Table 2]

[0078]
【The invention's effect】
The present invention
[0079]
A first layer containing an ethylene / α-olefin copolymer having a density satisfying specific conditions of 0.86 to 0.94 g / cm ³ and MFR of 0.1 to 50 g / 10 min; and (B) an ethylene-based heavy by forming a laminate of a layer of a II including the coalescing, self-adhesive and anti-tear propagation resistance, puncture strength, breaking strength, mechanical strength such as elongation at break, transparency, stretchability, tying property, etc. It is intended to provide a stretch film excellent in the above.
[Brief description of the drawings]
FIG. 1 shows an elution temperature-elution amount curve (TREF curve) of a copolymer of the present invention.
FIG. 2 shows an elution temperature-elution amount curve (TREF curve) of a copolymer with a typical metallocene catalyst.

Claims (7)

Copolymerization of ethylene and α-olefin having 3 to 20 carbon atoms, which are polymerized by a single site catalyst containing at least one transition metal of zirconium, titanium or hafnium and satisfy the following properties (a) to (f) A blend (A) of 100 to 20% by weight, another ethylene polymer (B) containing a first resin layer containing 0 to 80% by weight, and (B1) a Ziegler-type catalyst density of 0.86 to 0.94 g / a laminate comprising a cm ³ ethylene-α-olefin copolymer, and (B2) a second resin layer made of (B) an ethylene-based polymer of at least one ethylene (co) polymer by high-pressure radical polymerization. A stretch film.
<Properties>
(A) Density is 0.86-0.94 g / cm ³
(A) Melt flow rate (MFR) 0.1-50 g / 10 min (U) Molecular weight distribution (Mw / Mn) 1.8-3.5
(D) The composition distribution parameter Cb is 1.10 to 2.00
(E) The amount X (wt%) of the orthodichlorobenzene (ODCB) soluble component at 25 ° C. and the density d and MFR (melt flow rate) satisfy the following relationship: a) The values of density d and MFR are d− When 0.008 log MFR ≧ 0.93, X <2.0
b) When the values of density d and MFR are d−0.008 log MFR <0.93 X <9.8 × 10 ³ × (0.9300−d + 0.008 log MFR) ² +2.0
(F) There are a plurality of peaks in the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF) , and the high temperature side peak in the plurality exists between 85 and 100 ° C. The stretch film according to claim 1, wherein the (a) density of the ethylene / α-olefin copolymer (A) of the first resin layer is 0.88 to 0.93 g / cm ³ .   The first resin layer is composed of a composition of 98 to 20% by weight of the ethylene / α-olefin copolymer (A) and 2 to 80% by weight of another ethylene polymer (B). Item 3. A stretch film according to item 1 or 2. Ethylene and carbon in the presence of a catalyst obtained by bringing the ethylene / α-olefin copolymer (A) of the first resin layer (A) at least the catalyst forming components (C1) to (C5) below into contact with each other. The stretch film according to any one of claims 1 to 3, which is an ethylene / α-olefin copolymer obtained by copolymerizing an α-olefin having a number of 3 to 20.
[Catalyst forming component]
(C1): a compound represented by the general formula Me ¹ R ¹ _p (OR ² ) _q X ¹ _4-pq (wherein Me ¹ represents Zr, Ti, Hf, R ¹ and R ² represent Each hydrocarbon group having 1 to 24 carbon atoms, X ¹ represents a halogen atom, and p, q and r are integers satisfying the ranges of 0 ≦ p <4 and 0 ≦ p + q ≦ 4),
(C2): a compound represented by the general formula Me ² R ³ _m (OR ⁴ ) _n X ² _z-mn (wherein Me ² is a group I-III element of the periodic table, R ³ and R ⁴ are Each hydrocarbon group having 1 to 24 carbon atoms, X ² represents a halogen atom or a hydrogen atom (however, when X ² is a hydrogen atom, Me ² is limited to a group III element in the periodic table), and z is Me ^{2 represents} the valence, and m and n are integers satisfying the ranges of 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively, and 0 ≦ m + n ≦ z).
(C3): an organic cyclic compound having a conjugated double bond,
(C4): a modified organoaluminum compound containing an Al—O—Al bond obtained by a reaction between an organoaluminum compound and water,
(C5): inorganic carrier and / or particulate polymer carrier   The other ethylene-based polymer (B) of the first resin layer is (B1) a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms by a Ziegler type catalyst, and (B2) by a high pressure radical polymerization method. The stretch film according to any one of claims 1 to 4, wherein the stretch film is at least one selected from ethylene-based (co) polymers. (B1) A copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms by a Ziegler type catalyst is a linear low density polyethylene having a density of 0.91 to 0.94 g / cm ³ , 0.86 to 91 g / cm ³ ultra-low density polyethylene, 0.86-0.91 ethylene / α-olefin copolymer rubber, (B2) ethylene (co) polymer by high pressure radical polymerization is ethylene homopolymer, ethylene The stretch film according to claim 5, wherein the stretch film is at least one selected from the group consisting of a vinyl ester copolymer, ethylene and an α, β-unsaturated carboxylic acid or a derivative thereof. (B1) an ethylene-α-olefin copolymer having a density of 0.86 to 0.94 g / cm ³ by a Ziegler type catalyst on both sides of the first layer, and (B2) an ethylene (co) polymer by high-pressure radical polymerization. The stretch film according to any one of claims 1 to 6, comprising a laminate provided with a second layer and a third layer made of at least one (B) ethylene-based polymer.

Images