JP3722918B2 - Polypropylene film - Google Patents

Description

【００１７】
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ー（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。
【００１８】
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他にも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。しかしながら、この近似計算では、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Ｒ² はかなり低く、値の精度は充分でない。尚、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。
【００１９】
本発明のエチレン単独重合体またはエチレン・α−オレフィン共重合体（Ｂ）は、（ホ）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。この際、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、図２に典型的なメタロセン触媒による共重合体のものを示す。このように、両者は顕著に異なる。
【００２０】
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（例えば、ブチルヒドロキシトルエン）を加えたＯＤＣＢに試料濃度が０．０５重量％となるように加え、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℃／分の冷却速度で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測定することにより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分析によれば、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。
【００２１】
本発明の、エチレン単独重合体またはエチレン・α−オレフィン共重合体（Ｂ）の（ヘ）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、

の関係を満足していることが必要である。
【００２２】
本発明のエチレン単独重合体またはエチレン・α−オレフィン共重合体（Ｂ）の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濾過して濾液を採取する。この濾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、予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可溶分量が求まる。
【００２３】
２５℃におけるＯＤＣＢ可溶分は、エチレン単独重合体またはエチレン・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為、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。
【００２４】
本発明のエチレン・α−オレフィン共重合体（Ｂ）に用いられるα−オレフィンは炭素数３〜２０のものであり、好ましくは炭素数３〜１２のものであり、具体的にはプロピレン、１−ブテン、１−ペンテン、４−メチル−１−ペンテン、１−ヘキセン、１−オクテン、１−デセン、１−ドデセンなどが挙げられる。これらのα−オレフィンの含有量は、合計で通常３０モル％以下、好ましくは２０モル％以下の範囲で選択されることが望ましい。
【００２５】
本発明の特定のエチレン・α−オレフィン共重合体（Ｂ）は、好ましくは以下のａ１〜ａ４の触媒を用いて重合して製造することが望ましい。
ａ１：一般式Ｍｅ¹ Ｒ¹ _p （ＯＲ² ）_q Ｘ¹ _4-p-qで表される化合物（式中Ｍｅ ¹ はジルコニウム、チタンまたはハフニウムを示し、Ｒ¹ およびＲ² はそれぞれ炭素数１〜２４の炭化水素基、Ｘ¹ はハロゲン原子を示し、ｐおよびｑはそれぞれ０≦ｐ＜４、０≦ｐ＋ｑ≦４の範囲を満たす整数である）。
ａ２：一般式Ｍｅ² Ｒ³ _m （ＯＲ⁴ ）_n Ｘ² _z-m-n で表される化合物（式中Ｍｅ² は周期律表第Ｉ〜ＩＩＩ族元素、Ｒ³ およびＲ⁴ はそれぞれ炭素数１〜２４の炭化水素基、Ｘ² はハロゲン原子または水素原子（ただし、Ｘ² が水素原子の場合はＭｅ² は周期律表第ＩＩＩ族元素の場合に限る）を示し、ｚはＭｅ² の価数を示し、ｍおよびｎはそれぞれ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）。
ａ３：共役二重結合を持つ有機環状化合物。
ａ４：Ａｌ−Ｏ−Ａｌ結合を含む変性有機アルミニウムオキシ化合物を相互に接触させて得られる触媒。
【００２６】
以下、さらに詳説する。
上記触媒成分ａ１の一般式Ｍｅ¹ Ｒ¹ _p （ＯＲ² ）_q Ｘ¹ _4-p-qで表される化合物の式中、Ｍｅ¹ はジルコニウム、チタンまたはハフニウムを示し、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。Ｒ¹ およびＲ² はそれぞれ炭素数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である。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、ネオフィ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。Ｘ¹ 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す。ｐおよびｑはそれぞれ、０≦ｐ＜４、０≦ｐ＋ｑ≦４の範囲を満たす整数である。
【００２７】
上記触媒成分ａ１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 化合物が好ましく、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ａ２の一般式Ｍｅ² Ｒ³ _m （ＯＲ⁴ ）_n Ｘ² _z-m-n で表される化合物の式中Ｍｅ² 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。Ｒ³ およびＲ⁴ はそれぞれ炭素数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、ネオフィ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。Ｘ² 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、Ｘ² が水素原子の場合はＭｅ² 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Ｍｅ² の価数を示し、ｍおよびｎはそれぞれ、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ａ２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ａ３の共役二重結合を持つ有機環状化合物には、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_L ＳｉＲ_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ａ３の有機環状炭化水素化合物の具体例として、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などが挙げられる。
【００３４】
触媒成分ａ４のＡｌ−Ｏ−Ａｌ結合を含む変性有機アルミニウムオキシ化合物とは、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オキシ化合物が得られ、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オキシ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】
上記触媒はａ１〜ａ４を混合接触させて使用させてもよいが、好ましくは無機担体および／または粒子状ポリマー担体（ａ５）に担持させて使用することが望ましい。
触媒成分ａ５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性樹脂、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、ＳｉＯ₂ 、Ａｌ₂ Ｏ₃ 、ＭｇＯ、ＺｒＯ₂ 、ＴｉＯ₂ 、Ｂ₂ Ｏ₃ 、ＣａＯ、ＺｎＯ、ＢａＯ、ＴｈＯ₂ 等またはこれらの混合物が挙げられ、ＳｉＯ₂ −Ａｌ₂ Ｏ₃ 、ＳｉＯ₂ −Ｖ₂ Ｏ₅ 、ＳｉＯ₂ −ＴｉＯ₂ 、ＳｉＯ₂ −Ｖ₂ Ｏ₅ 、ＳｉＯ₂ −ＭｇＯ、ＳｉＯ₂ −Ｃｒ₂ Ｏ₃ 等が挙げられる。これらの中でもＳｉＯ₂ およびＡｌ₂ Ｏ₃ 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。
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。
【００３７】
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オキシ化合物などに接触処理させた後に成分ａ５として用いることもできる。
【００３８】
前記した条件（イ）〜（ヘ）を満足するエチレン単独重合体またはエチレン・α−オレフィン共重合体（Ｂ）は分子量分布および組成分布が狭いため、機械的強度が強く、ヒートシール性、抗ブロッキング性に優れしかも耐熱性の良い共重合体である。
【００３９】
前記エチレン単独重合体またはエチレン・α−オレフィン共重合体（Ｂ）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。
【００４０】
本発明の（Ａ）成分と（Ｂ）成分の配合組成は（Ａ）成分９７〜５０重量％、（Ｂ）成分３〜５０重量％である。（Ｂ）成分の量が３重量％未満ではフィルム強度の改善の目的が達せられず、５０重量％を越えると剛性率の低下が大きくなる。
（Ａ）成分と（Ｂ）成分の配合方法は公知の技術が使用でき、代表的な例としてはヘンシェルミキサー、押出機、ブラベンダーなどの通常の混練機を使用してのドライブレンド、溶融混合などの方法が挙げられる。
【００４１】
上記のように（Ａ）成分、（Ｂ）成分を所望の割合で配合した後、フィルムに成形する。フィルムの主な成形方法としては、水冷インフレーション法、空冷インフレーション法、Ｔダイ法があり、特にＴダイ法が好ましい。
また、ドライラミネート法、押出ラミネート法、サンドイッチラミネート法、共押出法等により各種基材に押出コーティングあるいは基材と共押出することによりフィルム化することも可能である。
このようにして得られたポリプロピレン系樹脂フィルムはその少なくとも一部分に他のフィルム等を積層して複合フィルムとすることもできる。すなわち、各種基材とシーラント基材とのサンドイッチラミネート基材として使用することもできる。
上記各種基材としては、紙、アルミニウム箔、セロファン、織布、布織布、各種樹脂フィルム、たとえば高密度ポリエチレン、直鎖状低密度ポリエチレン、低密度ポリエチレン、エチレン・酢酸ビニル共重合体、エチレン・アクリル酸エステル共重合体、アイオノマー、プロピレン系重合体、ポリ−１−ブテン、ポリ−４−メチル−１−ペンテン等のオレフィン系重合体、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリスチレン、ポリアクリレート、ポリアクリロニトリル等のビニル共重合体、ナイロン−６、ナイロン−６６、ナイロン−７、ナイロン−１０、ナイロン−１１、ナイロン−１２、ナイロン−６１０、ポリメタキシレンアジパミド等のポリアミド、ポリエチレンテレフタレート／イソフタレート、ポリブチレンテレフタレート等のポリエステル、ポリビニルアルコール、エチレン・ビニルアルコール共重合体、ポリカーボネート、ポリウレタン等を挙げることができる。
【００４２】
本発明で用いる樹脂組成物には必要に応じて、酸化防止剤、粘着付与剤、有機もしくは無機系顔料、有機もしくは無機フィラー、抗ブロッキング剤、核剤、紫外線など特定波長の光線を吸収する光線吸収剤、老化防止剤、耐熱性付与剤、可塑剤などの各種添加剤を適宜配合することが可能である。
また、さらに本発明の特性を本質的に阻害しない範囲で滑剤、防曇剤、分散剤、発泡剤、難燃剤、架橋剤、補強剤、充填剤などの公知の添加剤を添加することができる。
【００４３】
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。
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。
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。
【００４４】
さらに帯電防止性、防曇性を得るための添加剤も配合することができる。
具体的には、ソルビタン脂肪酸エステルとして、ソルビタンモノオレート、ソルビタンモノラウレート、ソルビタンモノベヘネート、ソルビタンモノステアレート等；グリセリン脂肪酸エステルとして、グリセリンモノオレート、グリセリンモノステアレート、グリセリンモノラウレート、グリセリンモノベヘネート等；ポリグリセリン脂肪酸エステルとして、ジグリセリンモノラウレート、ジグリセリンモノステアレート、ジグリセリンモノオレート、テトラグリセリンモノオレート、テトラグリセリンモノステアレート、ヘキサグリセリンモノラウレート、ヘキサグリセリンモノオレート、デカグリセリンモノラウレート、デカグリセリンモノステアレート、デカグリセリンモノオレート等の他、多価アルコールの脂肪酸エステルおよびこれらのエチレンオキサイド付加物、高級脂肪酸アミドおよびこれらのエチレンオキサイド付加物、高級脂肪酸アルカノールアミド等が挙げられるがこれらに限定されるものではない。
これらの添加剤は単独あるいは混合組成物として使用されるが、添加量としては通常０．０１〜０．５重量％、好ましくは０．０５〜０．３重量％である。添加量が０．０１重量％未満ではフィルムの改質効果が十分ではなく、０．５重量％を越える場合にはフィルム表面への浮き出し量が多く、フィルムがべたつき、その結果、作業性が著しく低下するなどの問題が起こるため好ましくない。
【００４５】
また、本発明においてフィルムの成形時等に発生するフィルムのロス分については再生原料としてフィルム物性を損なわない範囲で原料に添加することが可能である。
【００４６】
【発明の実施形態】
以下、本発明を実施例および比較例に基づいて具体的に説明するが、本発明はこれらによって限定されるものではない。
【００４７】
実施例および比較例における試験法は以下の通りである。
〔密度〕
ＪＩＳ Ｋ６７６０準拠。
〔ＭＦＲ〕
ＪＩＳ Ｋ６７６０準拠。
〔ヘイズ〕
ＡＳＴＭ Ｄ１００３準拠。
〔引張降伏強さ〕〔引張破壊強さ〕〔引張破壊伸び〕
ＡＳＴＭ Ｄ８８２準拠。
〔引張弾性率〕
インストロン型引張試験機を用い、フィルム幅２０ｍｍ、つかみ間隔２５０ｍｍ、引張速度２５ｍｍ／ｍｉｎで引っ張り、フィルムが１％変形したときの荷重より求めた。
〔フィルム衝撃強さ〕
振り子式機構のインパクト衝撃試験機（東洋精機（株）製）に１／２インチ球を取り付け、５℃におけるフィルムの衝撃破壊強さを求めた。
〔ヒートシール温度〕
製造したフィルムから押出方向（ＭＤ方向）に平行に幅１５ｍｍの短冊状のフィルムを切出し、それらの２枚を一組としてシールバーの幅５ｍｍ、シール圧力２ｋｇｆ／ｃｍ² 、シール時間１秒の条件でＭＤ方向に直角方向（ＴＤ）方向にヒートシールを行い試験片とした。この試験片をインストロン型引張試験機を用いて引張速度３００ｍｍ／ｍｉｎで引っ張り、３００ｇｆ／１５ｍｍ幅の荷重が得られる温度をヒートシール温度とした。
【００４８】
実施例および比較例に用いた各種成分は以下の通りである。
使用した樹脂の内（Ｂ）成分については次の方法で重合した。
【００４９】
（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）₂ Ｃｌ₂ ）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。
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３００ｍ² ／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。ついて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。
【００５０】
（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／ｃｍ² Ｇ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。
【００５１】

【００５２】
〔実施例１〜３〕および〔比較例１〜５〕
表１の成分をそれぞれ所定の割合でドライブレンドした後、シリンダー内径５０ｍｍ、スクリューのＬ／Ｄ＝２２の押出機を用いてＴダイ法により２４０℃で溶融押出を行い、厚さ３０μｍのフィルムに成形した。
前記の試験項目について測定を行い、結果をあわせて表１に示した。
いずれも
【００５３】
〔実施例４〜５〕および〔比較例６〜９〕
表１の成分をそれぞれ所定の割合でドライブレンドした後、シリンダー内径５０ｍｍ、スクリューのＬ／Ｄ＝２４の押出機を用いて水冷インフレーション法により２１０℃で押出しを行い、ブローアップ比１．５、水温２５℃で、厚さ３０μｍのフィルムに成形した。
前記の試験項目について測定を行い、結果をあわせて表１に示した。
【００５４】
【発明の効果】
本発明によるポリプロピレン系フィルムは透明性、ヒートシール性、衝撃強度、引き裂き強度、加工性等に優れ、フィルムの作業性も良好であることから、各種包装分野、たとえば野菜、魚肉等の生鮮食品、スナック、麺類等の乾燥食品、スープ、漬物等の水物食品等各種食品包装分野、錠剤、粉末、液体等の各種形態の医療品、また医療周辺材料等に用いる医療関連品包装分野、電気部品やカセットテープ等の各種電気機器周辺品や各種電気機器包装分野等、広範な分野への適用が可能である。
【００５５】
【表１】

【００５６】
【表２】

【００５７】
【表３】

【００５８】
【表４】

【００５９】
【表５】

【図面の簡単な説明】
【図１】本発明で用いるエチレン・α−オレフィン共重合体（Ｂ）のＴＲＥＦ曲線を示すグラフである。
【図２】メタロセン触媒によるエチレン・α−オレフィン共重合体のＴＲＥＦ曲線を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packaging film made of a polypropylene resin composition. More particularly, the present invention relates to a polypropylene film for packaging that has good transparency and heat sealability and a good balance between waist strength (rigidity) and impact resistance.
[0002]
[Prior art]
Films using polypropylene resins are used in fields such as food packaging, electrical component / peripheral equipment packaging, medical-related product packaging, and miscellaneous goods packaging. In general, a film using a polypropylene resin has high rigidity, but there are problems in terms of impact strength, tear strength, and the like. Moreover, the low temperature heat sealability is not sufficient, and an improvement is desired. By the way, among the qualities required for polypropylene resin films, the most important factor is transparency. However, it is necessary to improve the above-mentioned problems without reducing the required level of transparency.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a polypropylene resin film for packaging which is excellent in film strength such as transparency, low-temperature heat sealability, impact strength and tear strength.
[0004]
[Means for Solving the Problems]
As a result of intensive studies, the present inventor has achieved the above object by blending a polypropylene resin with an ethylene homopolymer or an ethylene / α-olefin copolymer satisfying specific parameters.
[0005]
In the presence of a catalyst containing (A) a polypropylene-based resin, an organic cyclic compound having at least a conjugated double bond, and a transition metal compound of Group IV of the periodic table, ethylene or ethylene and 3 to 20 carbon atoms are present. Polypropylene resin for packaging comprising an ethylene homopolymer or an ethylene / α-olefin copolymer (B) satisfying the following requirements (a) to (f) obtained by (co) polymerizing an α-olefin: the film.
(A) Density is 0.86-0.97 g / cm ³
(B) Melt flow rate of 0.01 to 100 g / 10 min (c) Molecular weight distribution (Mw / Mn) of 1.5 to 5.0
(D) The composition distribution parameter Cb is 1.08 to 2.00
(E) There are substantially a plurality of peaks in the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF). (F) The amount of orthodichlorobenzene (ODCB) soluble component X (wt%) at 25 ° C. The density d and MFR (melt flow rate) satisfy the following relationship: a) When d−0.008log MFR ≧ 0.93
X <2.0
b) When d−0.008log MFR <0.93
X <9.8 × 10 ³ × (0.9300 −d + 0.008logMF R ) ² +2.0
[0006]
The present invention will be described in detail below.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The polypropylene-based polymer used in the present invention is a homopolymer of propylene or a random or block copolymer with another α-olefin mainly composed of propylene, but from the viewpoint of mechanical strength and transparency. A homopolymer of propylene is desirable.
The propylene polymer has an MFR of 0.1 to 30 g / 10 minutes, preferably 1 to 20 g / 10 minutes, more preferably 1 to 10 g / 10 minutes. If the MFR is less than 0.1 g / 10 minutes, the fluidity of the molten resin is poor, the load on the extruder increases, and the surface of the film becomes rough, which is not preferable. On the other hand, if the MFR exceeds 30 g / 10 min, the mechanical strength of the film decreases, which is not preferable.
[0008]
The component (B) used in the present invention is an ethylene homopolymer or an ethylene / α-olefin copolymer that satisfies the following requirements (a) to (f).
(A) Density is 0.86-0.97 g / cm ³
(B) Melt flow rate of 0.01 to 100 g / 10 min (c) Molecular weight distribution (Mw / Mn) of 1.5 to 5.0
(D) The composition distribution parameter is 1.08 to 1.2
(E) There are substantially a plurality of peaks of the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF).
(F) The amount of orthodichlorobenzene (ODCB) soluble component X (wt%) at 25 ° C., density d and MFR (melt flow rate) satisfy the following relationship.
a) When d-0.008log MFR ≧ 0.93, X <2.0
b) When d−0.008log MFR <0.93 X <9.8 × 10 ³ × (0.9300 −d + 0.008 log MFR) ² +2.0
[0009]
The specific ethylene homopolymer or ethylene / α-olefin copolymer (B) of the present invention has (a) a density of 0.86 to 0.97 g / cm ³ , preferably 0.88 to 0.94 g / cm. ³ , more preferably in the range of 0.89 to 0.94 g / cm ³ . If the density is less than 0.86 g / cm ³ , the rigidity and heat resistance are poor, and if it is 0.96 g / cm ³ or more, the impact resistance is not sufficient.
[0010]
(B) The melt flow rate is in the range of 0.01 to 100 g / 10 minutes, preferably 0.03 to 50 g / 10 minutes, more preferably 0.05 to 30 g / 10 minutes. When the MRF is less than 0.01 / 10 minutes, the moldability is poor, and when it is 100 g / 10 minutes or more, the strength is lowered.
[0011]
(C) The molecular weight distribution (Mw / Mn) is 1.5 to 5.0, preferably 1.6 to 4.0, more preferably 1.8 to 3.5. When Mw / Mn is less than 1.5, the moldability is inferior, and when it exceeds 5.0, the impact resistance is inferior.
The calculation method of Mw / Mn is obtained by calculating | requiring a weight average molecular weight (Mw) and a number average molecular weight (Mn) by gel permeation chromatography (GPC), and calculating those ratio (Mw / Mn).
[0012]
The (d) composition distribution parameter (Cb) of the ethylene homopolymer or ethylene / α-olefin copolymer (B) of the present invention is 1.08 to 2.00. Preferably it is in the range of 1.10 to 1.80, more preferably 1.12 to 1.70.
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.
[0013]
The method for measuring the composition distribution parameter (Cb) is as follows.
It is dissolved by heating at 135 ° C. in orthodichlorobenzene (ODCB) to which an antioxidant (for example, butylhydroxytoluene) 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 (number of branches per 1000 carbon atoms) are measured by ¹³ C-NMR.
[0014]
For the fraction from 30 ° C. to 90 ° C., the following degree of branching correction is performed. Plot the degree of branching measured against the elution temperature, approximate the correlation to a straight line using the least squares method, and create a calibration curve. 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.
[0015]
Next, the relative concentration c _i is obtained by dividing the weight fraction wi of each fraction by the amount of change (b _i -b _i-1 ) of the branching degree b _i per elution temperature of 5 ° C. 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.
[0016]
[Expression 1]

[0017]
Here, c _j and b _j are the relative density and the branching degree of the jth 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.
[0018]
Many other methods for describing the composition distribution of the ethylene / α-olefin copolymer have been proposed. For example, in JP-A-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. However, in this approximate calculation, the accuracy drops when the number of sample branches and the cumulative weight fraction deviate from the lognormal distribution, and the correlation coefficient R ² is considerably low when measurements are performed on commercially available LLDPE, and the accuracy of the values is not sufficient. . Although the Cw / Cn measurement method and the numerical processing method are different from those of Cb of the present invention, the value of Cw / Cn is considerably larger than Cb when the numerical values are compared.
[0019]
The ethylene homopolymer or ethylene / α-olefin copolymer (B) of the present invention has (e) a plurality of peaks in the elution temperature-elution amount curve determined by the continuous temperature rising elution fractionation method (TREF). It is necessary. At this time, 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 typical metallocene catalyst copolymer. Thus, the two are significantly different.
[0020]
The method for measuring TREF according to the present invention is as follows. A sample is added to ODCB to which an antioxidant (for example, butylhydroxytoluene) is added so that the sample concentration is 0.05% by weight, and is heated and dissolved at 135 ° C. 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 measuring the absorption with respect to the wave number of 2925 cm ⁻¹ of the asymmetric stretching vibration of methylene with an infrared detector. 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. According to the TREF analysis, since a change in elution rate with respect to a temperature change can be continuously analyzed with a very small amount of sample, a relatively fine peak that cannot be detected by a fractionation method can be detected.
[0021]
In the present invention, the relationship between the amount x (% by weight) of the ODCB soluble component at 25 ° C. of the ethylene homopolymer or ethylene / α-olefin copolymer (B) and the density d and MFR is as follows: d and MFR Value of

It is necessary to satisfy the relationship.
[0022]
The amount of the ODCB soluble component at 25 ° C. of the ethylene homopolymer or ethylene / α-olefin copolymer (B) 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. An absorption peak area in the vicinity of a 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 amount of soluble ODCB at 25 ° C. is obtained.
[0023]
The ODCB soluble component at 25 ° C. is a high branching degree component and a low molecular weight component contained in the ethylene homopolymer or ethylene / α-olefin copolymer, and causes sanitary problems and blocking of the inner surface of the molded product. Therefore, it is desirable that this content is small. 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.
[0024]
The α-olefin used in the ethylene / α-olefin copolymer (B) of the present invention has 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms, specifically propylene, 1 -Butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and the like. The total content of these α-olefins is usually 30 mol% or less, preferably 20 mol% or less.
[0025]
The specific ethylene / α-olefin copolymer (B) of the present invention is preferably produced by polymerization using the following catalysts a1 to a4.
a1: formula _{^{Me 1 R 1 p (OR 2}} ) q X 1 compound represented by the _4-pq (wherein Me ¹ represents zirconium, titanium or hafnium, R ¹ and R ² each having 1 to 24 carbon atoms And X ¹ represents a halogen atom, and p and q are integers satisfying the ranges of 0 ≦ p <4 and 0 ≦ p + q ≦ 4, respectively.
a2: a compound represented by the general formula Me ² R ³ _m (OR ⁴ ) _n X ² _zmn (wherein Me ² is a group I-III element of the periodic table, R ³ and R ⁴ are each 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 represents the valence of Me ² M and n are integers satisfying the ranges of 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively, and 0 ≦ m + n ≦ z).
a3: An organic cyclic compound having a conjugated double bond.
a4: a catalyst obtained by bringing modified organoaluminum oxy compounds containing Al—O—Al bonds into contact with each other.
[0026]
Further details will be described below.
Of general formula _{^{Me 1 R 1 p (OR 2}} ) q X 1 compound represented by the _4-pq of the catalyst component a1, Me ¹ represents zirconium, titanium or hafnium, these types of transition metals are limited A plurality of them may be used, but it is particularly preferable that zirconium having excellent weather resistance of the copolymer is contained. 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, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group and butyl group; alkenyl groups such as vinyl group and allyl group; phenyl group, tolyl group, xylyl group, mesityl group, indenyl group and naphthyl group Aryl groups such as benzyl groups, trityl groups, phenethyl groups, styryl groups, benzhydryl groups, phenylbutyl groups, neophyll groups, and the like. These may be branched. X ¹ represents a halogen atom such as fluorine, iodine, chlorine and bromine. p and q are integers satisfying the ranges of 0 ≦ p <4 and 0 ≦ p + q ≦ 4, respectively.
[0027]
Examples of the compound represented by the general formula of the catalyst component a1 include tetramethylzirconium, tetraethylzirconium, tetrabenzylzirconium, tetrapropoxyzirconium, tripropoxymonochlorozirconium, tetrabutoxyzirconium, tetrabutoxytitanium, tetrabutoxyhafnium and the like. In particular, Zr (OR) ₄ compounds such as tetrapropoxyzirconium and tetrabutoxyzirconium are preferable, 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 a2 wherein Me ² in the compound represented by _n X ² _Zmn 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, 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 group Aralkyl groups such as benzhydryl group, phenylbutyl group and neophyll group. These may be branched. X ² represents a halogen atom or 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 a2 include organic lithium compounds such as methyl lithium and ethyl lithium; organic magnesium 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 a3 has one or two rings which 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 component a3 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 oxy compound containing an Al—O—Al bond of the catalyst component a4 is obtained by reacting an alkylaluminum compound with water to obtain a modified organoaluminum oxy compound usually referred to as an aluminoxane. Usually, it contains 1 to 100, preferably 1 to 50 Al—O—Al bonds. The modified organoaluminum oxy 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]
The catalyst may be used by mixing and contacting a1 to a4, but preferably it is used by supporting it on an inorganic carrier and / or a particulate polymer carrier (a5).
Examples of the inorganic carrier and / or the particulate polymer carrier of the catalyst component a5 include carbonaceous materials, metals, metal oxides, metal chlorides, metal carbonates or mixtures thereof, thermoplastic resins, thermosetting resins, and the like. Suitable metals that can be used for the inorganic carrier include iron, aluminum, nickel and the like.
Specific examples include SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO _2, or a mixture thereof, and SiO ₂ —Al ₂ O _3. SiO ₂ —V ₂ O ₅ , SiO ₂ —TiO ₂ , SiO ₂ —V ₂ O ₅ , SiO ₂ —MgO, SiO ₂ —Cr ₂ O _{3 and the} like. Among these, those containing as a main component at least one component selected from the group consisting of SiO ₂ and Al ₂ O ₃ are preferable.
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.
[0037]
The inorganic carrier and / or the particulate polymer carrier can be used as they are, but preferably the carrier is contacted with an organoaluminum compound or a modified organoaluminum oxy compound containing an Al—O—Al bond as a pretreatment. It can also be used as component a5 after having been used.
[0038]
The ethylene homopolymer or ethylene / α-olefin copolymer (B) satisfying the above-mentioned conditions (a) to (f) has a narrow mechanical weight distribution and a composition distribution, so that it has a high mechanical strength, heat sealability, It is a copolymer having excellent blocking properties and good heat resistance.
[0039]
The method for producing the ethylene homopolymer or ethylene / α-olefin copolymer (B) 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 multistage polymerization method. Absent.
[0040]
The blending composition of the (A) component and the (B) component of the present invention is 97 to 50% by weight of the (A) component and 3 to 50% by weight of the (B) component. If the amount of the component (B) is less than 3% by weight, the purpose of improving the film strength cannot be achieved, and if it exceeds 50% by weight, the rigidity decreases greatly.
Known methods can be used for the blending method of component (A) and component (B). Typical examples include dry blending and melt mixing using a normal kneader such as a Henschel mixer, an extruder, or a Brabender. And the like.
[0041]
After blending the component (A) and the component (B) at a desired ratio as described above, it is formed into a film. Main film forming methods include a water-cooled inflation method, an air-cooled inflation method, and a T-die method, with the T-die method being particularly preferred.
It is also possible to form a film by extrusion coating or co-extrusion with various substrates by dry lamination method, extrusion lamination method, sandwich lamination method, co-extrusion method or the like.
The polypropylene resin film thus obtained can be made into a composite film by laminating another film or the like on at least a part thereof. That is, it can also be used as a sandwich laminate substrate of various substrates and a sealant substrate.
Examples of the various substrates include paper, aluminum foil, cellophane, woven fabric, woven fabric, various resin films such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ethylene / vinyl acetate copolymer, ethylene Acrylic ester copolymer, ionomer, propylene polymer, olefin polymer such as poly-1-butene, poly-4-methyl-1-pentene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylate, Vinyl copolymers such as polyacrylonitrile, nylon-6, nylon-66, nylon-7, nylon-10, nylon-11, nylon-12, nylon-610, polyamides such as polymetaxylene adipamide, polyethylene terephthalate / Isophthalate, polybutylene terephthalate, etc. Polyester, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polycarbonates, can be cited polyurethane or the like.
[0042]
The resin composition used in the present invention absorbs light having a specific wavelength such as an antioxidant, a tackifier, an organic or inorganic pigment, an organic or inorganic filler, an antiblocking agent, a nucleating agent, and ultraviolet rays as necessary. Various additives such as an absorbent, an anti-aging agent, a heat resistance imparting agent, and a plasticizer can be appropriately blended.
Furthermore, known additives such as a lubricant, an antifogging agent, a dispersant, a foaming agent, a flame retardant, a crosslinking agent, a reinforcing agent, and a filler can be added as long as the characteristics of the present invention are not essentially impaired. .
[0043]
Among these additives, a lubricant and an inorganic filler are preferably used in order to further improve workability.
Examples of lubricants 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; Is mentioned.
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.
[0044]
Furthermore, additives for obtaining antistatic properties and antifogging properties can also be blended.
Specifically, as sorbitan fatty acid ester, sorbitan monooleate, sorbitan monolaurate, sorbitan monobehenate, sorbitan monostearate, etc .; as glycerol fatty acid ester, glycerol monooleate, glycerol monostearate, glycerol monolaurate, glycerol Monobehenate, etc .; as polyglycerol fatty acid ester, diglycerol monolaurate, diglycerol monostearate, diglycerol monooleate, tetraglycerol monooleate, tetraglycerol monostearate, hexaglycerol monolaurate, hexaglycerol monooleate, In addition to decaglycerin monolaurate, decaglycerin monostearate, decaglycerin monooleate, etc., fatty acid esters of polyhydric alcohols and These ethylene oxide adducts, higher fatty acid amides and their ethylene oxide adducts, does not but such higher fatty acid alkanolamides as being limited thereto.
These additives are used alone or as a mixed composition, and the amount added is usually 0.01 to 0.5% by weight, preferably 0.05 to 0.3% by weight. If the added amount is less than 0.01% by weight, the effect of modifying the film is not sufficient. If the added amount exceeds 0.5% by weight, the amount of protrusion on the surface of the film is large and the film becomes sticky. This is not preferable because a problem such as reduction occurs.
[0045]
In the present invention, the loss of the film that occurs when the film is formed or the like can be added to the raw material as a raw material within a range that does not impair the film properties.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited by these.
[0047]
Test methods in Examples and Comparative Examples are as follows.
〔density〕
Conforms to JIS K6760.
[MFR]
Conforms to JIS K6760.
[Haze]
Conforms to ASTM D1003.
(Tensile yield strength) (Tensile fracture strength) (Tensile fracture elongation)
Conforms to ASTM D882.
[Tensile modulus]
Using an Instron type tensile tester, the film was pulled at a film width of 20 mm, a grip interval of 250 mm, and a tensile speed of 25 mm / min, and obtained from the load when the film was deformed by 1%.
[Film impact strength]
A 1/2 inch ball was attached to an impact impact tester (manufactured by Toyo Seiki Co., Ltd.) with a pendulum mechanism, and the impact fracture strength of the film at 5 ° C. was determined.
[Heat seal temperature]
A strip-shaped film having a width of 15 mm is cut out from the produced film in parallel to the extrusion direction (MD direction), and the two sheets are combined as a set with a seal bar width of 5 mm, a seal pressure of 2 kgf / cm ² , and a seal time of 1 second. Then, heat sealing was performed in a direction perpendicular to the MD direction (TD) to obtain a test piece. The test piece was pulled at a tensile speed of 300 mm / min using an Instron type tensile tester, and the temperature at which a load of 300 gf / 15 mm width was obtained was defined as the heat seal temperature.
[0048]
Various components used in Examples and Comparative Examples are as follows.
The component (B) in the used resin was polymerized by the following method.
[0049]
(Preparation of solid catalyst)
Purified toluene was added to a catalyst preparation device (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.
Next, purified toluene was added to a preparator equipped with a stirrer under nitrogen (No. 1), and then 1400 g of silica (made 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.
[0050]
(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. In order to keep the gas composition in the system constant by continuously supplying the catalyst C, the polymerization was performed while continuously supplying each gas.
[0051]

[0052]
[Examples 1 to 3] and [Comparative Examples 1 to 5]
After the components shown in Table 1 were dry blended at a predetermined ratio, melt extrusion was performed at 240 ° C. by a T-die method using an extruder having a cylinder inner diameter of 50 mm and a screw L / D = 22 to form a film having a thickness of 30 μm. Molded.
The above test items were measured and the results are shown in Table 1.
Both [0053]
[Examples 4 to 5] and [Comparative Examples 6 to 9]
After the components in Table 1 were dry blended at a predetermined ratio, extrusion was performed at 210 ° C. by a water-cooled inflation method using an extruder with a cylinder inner diameter of 50 mm and a screw L / D = 24, and a blow-up ratio of 1.5, The film was formed into a 30 μm thick film at a water temperature of 25 ° C.
The above test items were measured and the results are shown in Table 1.
[0054]
【The invention's effect】
Since the polypropylene film according to the present invention is excellent in transparency, heat sealability, impact strength, tear strength, workability, etc., and the workability of the film is also good, various packaging fields such as fresh foods such as vegetables and fish meat, Various food packaging fields such as dry foods such as snacks and noodles, marine foods such as soups and pickles, medical products in various forms such as tablets, powders and liquids, and medical related products packaging fields used for medical peripheral materials, electrical parts It can be applied to a wide range of fields such as various electrical equipment peripherals such as cassette tapes and various electrical equipment packaging fields.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
[Table 3]

[0058]
[Table 4]

[0059]
[Table 5]

[Brief description of the drawings]
FIG. 1 is a graph showing a TREF curve of an ethylene / α-olefin copolymer (B) used in the present invention.
FIG. 2 is a graph showing a TREF curve of an ethylene / α-olefin copolymer using a metallocene catalyst.

Claims (2)

97 to 50% by weight of the polypropylene resin (A) and ethylene or ethylene and 3 to 20 carbon atoms in the presence of a catalyst containing an organic cyclic compound having at least a conjugated double bond and a transition metal compound of Group IV of the periodic table The ethylene homopolymer or the ethylene / α-olefin copolymer (B) satisfying the following requirements (a) to (f) obtained by (co) polymerizing with an α-olefin of 3 to 50% by weight: A polypropylene film for packaging, characterized in that
(A) Density is 0.86-0.97 g / cm ³
(B) Melt flow rate of 0.01 to 100 g / 10 min (c) Molecular weight distribution (Mw / Mn) of 1.5 to 5.0
(D) The composition distribution parameter Cb is 1.08 to 2.00
(E) There are substantially a plurality of peaks in the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF). (F) The amount of orthodichlorobenzene (ODCB) soluble component X (wt%) at 25 ° C. The density d and MFR (melt flow rate) satisfy the following relationship: a) When d−0.008log MFR ≧ 0.93
X <2.0
b) When d−0.008log MFR <0.93
X <9.8 × 10 ³ × (0.9300-d + 0.008logMF R ) ² +2.0 In the presence of a catalyst containing 97 to 50% by weight of the polypropylene resin (A) and at least an organic cyclic compound having a conjugated double bond and a transition metal compound of Group IV of the periodic table, ethylene or ethylene and 3 to 20 carbon atoms Of α-olefin ( Both ) A resin composition obtained by mixing 3 to 50% by weight of an ethylene homopolymer or ethylene / α-olefin copolymer (B) satisfying the following requirements (a) to (f) obtained by polymerization: Is formed into a film by an inflation method or a T-die method, and a method for producing a polypropylene film for packaging.
(A) Density is 0.86-0.97 g / cm ³
(B) Melt flow rate 0.01 to 100 g / 10 min
(C) Molecular weight distribution (Mw / Mn) is 1.5 to 5.0
(D) The composition distribution parameter Cb is 1.08 to 2.00
(E) There are substantially multiple peaks in the elution temperature-elution volume curve by the continuous temperature rising elution fractionation method (TREF).
(F) The amount of orthodichlorobenzene (ODCB) soluble component X (wt%) at 25 ° C., density d, and MFR (melt flow rate) satisfy the following relationship:
a) When d−0.008log MFR ≧ 0.93
X <2.0
b) When d-0.008log MFR <0.93
X <9.8 × 10 ³ × ( 0.9300-d + 0.008log MFR ) ² +2.0

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