JP2004161799A - Biaxially oriented polyproylene film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially oriented polypropylene film having high rigidity in the lengthwise direction of the film with the use of the general-purpose lengthwise-crosswise consecutive biaxial orientation method. <P>SOLUTION: The biaxially oriented polypropylene film comprises a polypropylene having a Trouton's ratio of ≥30 and/or is composed of a polypropylene having a Trouton's ratio of ≥16 and/or comprises a polypropylene having a long-chain branching and, simultaneously, one or more stretching auxiliaries. <P>COPYRIGHT: (C)2004,JPO

Description

各試料は２３０℃で装置にセット・充填し、３分間保持した。さらに再充填し、３分間保持した後、測定を開始した。
【０１３８】
Ｃｏｇｓｗｅｌｌの理論によると、流入の際に毛管入り口で生じる圧力損失（ΔＰ_ｅｎｔ）は、剪断粘度と伸張粘度を用いて次式のように表せる。
ここで、η_Ｅ：伸張粘度、η_ｓ：剪断粘度、γ_ａ：剪断速度である。また、ｎはべき法則（σ_ｓ＝ｋγ_ａ ^ｎ、σ_ｓ：剪断応力）における流れ指数である。
ツインキャピラリ・レオメータでは、長さの異なる２つの毛管で同時測定することにより、ある剪断速度での剪断粘度、ΔＰ_ｅｎｔを同時に求めることができるので、伸張粘度η_Ｅは次式より求めることができる。
ここで、ε：伸張応力である。得られた伸張粘度−伸張ひずみ速度曲線、剪断粘度−剪断速度曲線をそれぞれ指数関数として近似し、これらの関数を用いて、ひずみ速度６０ｓ^−１でのη_{Ｅ（６０）}、η_{ｓ（６０）}を求めた。これより、次式によりひずみ速度６０ｓ^−１でのトルートン比（同じひずみ速度でのη_Ｅとη_ｓの比）を算出した。
（２）ヤング率、Ｆ２値、Ｆ５値、破断強度
２５℃でのヤング率、Ｆ２値、Ｆ５値は、（株）オリエンテック社製フィルム強伸度測定装置（ＡＭＦ／ＲＴＡ−１００）を用いて、６５％ＲＨにて測定した。サンプルを測定方向：１５ｃｍ、測定方向と直角の方向：１ｃｍのサイズに切り出し、原長５０ｍｍ、引張り速度３００ｍｍ／分で伸張して、ヤング率は、ＪＩＳ−Ｚ１７０２に規定された方法に従い測定した。また、Ｆ２値、Ｆ５値は、それぞれ伸度２％、５％に対する試料にかかる応力を測定した。破断強度は、サンプルが破断した際の応力また、８０℃などの高温で測定を行う際は、ゴンドー科学（株）社製高低温度恒温槽を装着し、上記と同様の条件にて測定した。
（３）メソペンタッド分率（ｍｍｍｍ）
ポリプロピレンをｏ−ジクロロベンゼン−Ｄ６に溶解させ、ＪＥＯＬ製ＪＮＭ−ＧＸ２７０装置を用い、共鳴周波数６７．９３ＭＨｚで^１３Ｃ−ＮＭＲを測定した。得られたスペクトルの帰属、およびメソペンタッド分率の計算については、Ｔ．Ｈａｙａｓｈｉらが行った方法（Ｐｏｌｙｍｅｒ、２９、１３８〜１４３（１９８８））に基づき、メチル基由来のスペクトルについて、ｍｍｍｍピークを２１．８５５ｐｐｍとして各ピークの帰属を行い、ピーク面積を求めてメチル基由来全ピーク面積に対する比率を百分率で表示した。詳細な測定条件は以下の通りである。
【０１３９】
測定濃度：１５〜２０ｗｔ％
測定溶媒：ｏ−ジクロロベンゼン（９０ｗｔ％）／ベンゼン−Ｄ６（１０ｗｔ％）
測定温度：１２０〜１３０℃
共鳴周波数：６７．９３ＭＨｚ
パルス幅：１０μ秒（４５°パルス）
パルス繰り返し時間：７．０９１秒
データ点：３２Ｋ
積算回数：８１６８
測定モード：ノイズデカップリング
（４）熱収縮率
測定方向を長手方向および幅方向として、フィルムから試長２６０ｍｍ、幅１０ｍｍにサンプリングし、原寸（Ｌ_０）として２００ｍｍの位置にマークを入れる。このサンプルの下端に３ｇの荷重をかけ、１２０℃の熱風循環オーブン中で１５分間熱処理した後室温中に取り出し、サンプルにマークした長さ（Ｌ_１）を測定する。この際、熱収縮率は次式により求められる。各方向（長手方向、幅方向）について上記操作を行い、長手方向と幅方向の熱収縮率、およびその和を求めた。
【０１４０】
熱収縮率（％）＝１００×（Ｌ_０−Ｌ_１）／Ｌ_０
（５）水蒸気透過率
ＭＯＣＯＮ／Ｍｏｄｅｒｎ Ｃｏｎｔｒｏｌｓ社製の水蒸気透過率測定装置ＰＥＲＭＡＴＲＡＮ−Ｗ３／３０を用いて、温度４０℃、湿度９０％ＲＨの条件で測定した。金属蒸着二軸延伸ポリプロピレンフィルムについては、金属蒸着を行った面に、ポリプロピレン製の粘着フィルム（３Ｍ社製、Ｓｃｏｔｃｈｍａｒｋ、４０μｍ厚み）を貼り合わせ、上記条件で測定した。
（６）固有粘度（［η］）
１３５℃のテトラリン中に溶解したポリプロピレンについて、三井東圧化学（株）製のオストワルド粘度計を用いて測定した。
（７）メルトフローレイト（ＭＦＲ）
ＪＩＳ Ｋ６７５８に示されるポリプロピレン試験方法（２３０℃、２．１６ｋｇｆ）に従って測定した。
（８）アイソタクチックインデックス（ＩＩ）
ポリプロピレンを６０℃以下の温度のｎ−ヘプタンで２時間抽出し、ポリプロピレン中の添加物を除去する。その後１３０℃で２時間真空乾燥する。これから重量Ｗ（ｍｇ）の試料を取り、ソックスレー抽出器に入れ沸騰ｎ−ヘプタンで１２時間抽出する。次に、この試料を取り出し、アセトンで十分洗浄した後、１３０℃で６時間真空乾燥し、その後常温まで冷却し、重量Ｗ’（ｍｇ）を測定し、次式で求めた。
【０１４１】
ＩＩ＝（Ｗ’／Ｗ）×１００（％）
（９）ガラス転移点温度（Ｔｇ）、融点（Ｔｍ）、結晶融解熱量（Ｈ）、結晶化温度（Ｔｍｃ）
Ｓｅｉｋｏ Ｉｎｓｔｒｕｍｅｎｔｓ社製熱分析装置ＲＤＣ２２０型に、サンプル重量５ｍｇとしてアルミニウムパンに封入して装填し、２０℃／分の速度で３０℃から２８０℃まで昇温し、得られた熱量曲線から同社製熱分析システムＳＳＣ５２００の内蔵プログラムを用い、ガラス転移の開始点をガラス転移温度（Ｔｇ）とし、さらに昇温する際に結晶の融解に伴う吸熱ピークの頂点を融点（Ｔｍ）とし、結晶融解熱量（Ｈ）はその面積から求めた。この面積は、熱量曲線が昇温に伴いベースラインから吸熱側にずれ、次いでベースラインの位置に戻るまでの面積であり、融解開始温度位置から終了温度位置までを直線で結び、この面積をコンピュータ処理して求めた。なお複数の吸熱ピークが観察される場合は、適宜コンピュータ処理でピーク分離を行い、それぞれ融解熱量を求めた。昇温完了後、２８０℃で５分間待機させ、引き続き２０℃／分の速度で３０℃まで降温した。この際溶融状態からの結晶化に伴う発熱ピークの頂点を結晶化温度（Ｔｍｃ）として求めた。
（１０）臭素価
ＪＩＳ Ｋ−２５４３−１９７９に準じて測定した。試料油１００ｇ中の不飽和成分に付加される臭素のｇ数で表される。
（１１）粒子の平均粒径（μｍ）
遠心沈降法（堀場製作所製 ＣＡＰＡ５００を使用）を用いて測定した体積平均径を平均粒径とした。
（１２）フィルムを構成する各層の厚み（μｍ）
フィルムをミクロトームを用いて切断し、断面を形成させ、電解放射型走査電子顕微鏡（ＦＥ−ＳＥＭ）を用いてフィルム断面構成観察を行い、各積層厚みを測定した。
（１３）直進手切れ性
フィルムの端部を親指と人差指で、左右の親指と左右の人差指同士が接するようにして持ち、フィルム端部をカット方向にひねるように急速な力を加えて引き裂く場合に、容易に真直ぐ手で引き裂くことができるものを○とし、容易には手で引き裂くことができないもの、真直ぐ引き裂けないものを×とした。
（１４）中心線平均表面粗さ（Ｒａ）
ＪＩＳ Ｂ０６０１に従って、触針式表面粗さ計を用いて測定した。なお、小坂研究所（株）製、高精度薄膜段差測定器（型式：ＥＴ−３０ＨＫ）を使用し、触針径円錐型０．５μｍＲ、荷重１６ｍｇ、カットオフは０．０８ｍｍとした。
【０１４２】
この時、中心線平均表面粗さ（Ｒａ）は、粗さ曲線からその中心線の方向に測定長さＬの部分を抜き取り、この抜き取部分の中心線をＸ軸、縦方向をＹ軸とし、粗さ曲線をｙ＝ｆ（ｘ）で表した時、次の式によって求められる値をμｍで表したものをいう。
（１５）表面濡れ張力
ホルムアミドとエチレングリコールモノエチルエーテルとの混合液によるＪＩＳ Ｋ６７６８に規定された測定方法に基づいて測定した。
（１６）実効延伸倍率
スリット状口金から押し出し、金属ドラムに巻き付けてシート上に冷却固化せしめた未延伸フィルムに、長さ１ｃｍ四方の升目をそれぞれの辺がフィルムの長手方向、幅方向に平行になるように刻印した後、延伸・巻き取りを行い、得られたフィルムの升目の長さ（ｃｍ）を測定し、これを長手方向・横方向の実効延伸倍率とした。
（１７）灰分
ＪＩＳ Ｃ２３３０にしたがい、初期重量Ｗ_０の二軸延伸ポリプロピレンフィルムを、白金坩堝に入れ、まずガスバーナーで十分に燃焼させた後、７５０〜８００℃の電気炉で、約１時間程度処理して完全に灰化し、得られた灰の重量Ｗ_１を測定し、下記式から算出した。
【０１４３】
灰分＝（Ｗ_１／Ｗ_０）×１００００００（ｐｐｍ）
（１８）フィルム絶縁破壊強度（ＢＤＶ）
ＪＩＳ Ｃ２１１０に従って測定した。陰極に厚み１００μｍ、１０ｃｍ角のアルミ箔電極、陰極に真鍮性８ｍｍφの電極を用い、この間にフィルムをはさみ、春日電気（株）製直流高圧安定化電源を用いて、１００Ｖ／秒の速度で昇圧しながら電圧を印加し、電流が１０ｍＡ以上流れた場合を絶縁破壊したものとした。その時の電圧を測定点のフィルム厚みで割った値を絶縁破壊強度とし、３０点測定した平均値で示した。また、バラツキは、該３０点のデータから標準偏差を算出し、求めた。
（１９）二次加工性
長さ１０００ｍの本発明の二軸延伸ポリプロピレンフィルムの片面に、厚さ２０μｍの未延伸ポリプロピレンフィルムをポリウレタン系の接着剤を用いてドライラミネートし、食品包装用フィルムとした。該フィルムを未延伸ポリプロピレンフィルム層が内側になるようにして、（株）フジキカイ製の縦型ピロー包装機（ＦＵＪＩ ＦＷ−７７）を用いて、フィルムを筒状に挿入し、製袋した。
【０１４４】
その際、フィルムにシワや伸びなどが入らず、製袋品の形状がよいものを○とし、フィルムの長手方向のヤング率が低かったり腰が低いために伸びたり、滑りが悪かったり、熱収縮率が大きいためにシワが入ったりして製袋品の形状が悪くなったものなどを×として評価した。
【０１４５】
【実施例】
本発明を実施例に基づいて説明する。なお、所望の厚みのフィルムを得るためには、特に断りのない限り、押出機の回転数と冷却ドラムの周速を所定の値に調節した。
【０１４６】
実施例１
トルートン比が１２の公知のポリプロピレン（メルトフローレート（ＭＦＲ）：２．３ｇ／１０分、メソペンタッド分率（ｍｍｍｍ）：９２％、アイソタクチックインデックス（ＩＩ）：９６％）に、トルートン比が５０の長鎖分岐を有するポリプロピレン（ＭＦＲ：３ｇ／１０分、ｍｍｍｍ：９７％、ＩＩ：９６．５％）５重量％の比率で添加混合したポリプロピレン９０重量％に、延伸助剤として、極性基を実質的に含まない石油樹脂である、Ｔｇ８０℃、臭素価３ｃｇ／ｇ、水添率９９％のポリジシクロペンタジエンを１０重量％添加混合した樹脂組成１００重量部に、架橋有機粒子として平均粒径２μｍのポリメタクリル酸系重合体の架橋粒子（架橋ＰＭＭＡ）を０．１５重量部添加し、帯電防止剤としてグリセリン脂肪酸エステルとアルキルジエタノールアミン脂肪酸エステルを１：１の割合に混合して０．８重量部添加し、二軸押出機に供給して２７０℃でガット状に押出し、２０℃の水槽に通して冷却してチップカッターで３ｍｍ長にカットした後、１００℃で２時間乾燥したチップを一軸押出機に供給して２８０℃で溶融させ、濾過フィルターを経た後にスリット状口金から押出し、２５℃の金属ドラムに巻き付けてシート状に成形した。
【０１４７】
このシートを１３５℃に保たれたロールに通して予熱し、１４０℃に保ち周速差を設けたロール間に通し、長手方向に９倍延伸して直ちに室温に冷却する。引き続きこの延伸フィルムをテンターに導入して１６５℃で予熱し、１６０℃で幅方向に７倍に延伸し、次いで幅方向に８％の弛緩を与えつつ、１６０℃で熱固定をした後、冷却して巻き取った厚さ１５μｍの二軸延伸ポリプロピレンフィルムを得た。
【０１４８】
得られたフィルムの原料組成とフィルム特性評価結果をまとめて表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１４９】
実施例２
実施例１において、長手方向の延伸倍率を１１倍に上げた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例２とした。
【０１５０】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１５１】
実施例３
実施例１において、延伸助剤として、極性基を実質的に含まないテルペン樹脂である、Ｔｇ７５℃、臭素価４ｃｇ／ｇ、水添率９９％のβ−ピネンを３重量％混合し、長手方向に８倍、幅方向に８倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例３とした。
【０１５２】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１５３】
実施例４
実施例３において、延伸助剤のテルペン樹脂の混合量を８重量％とした以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例４とした。
【０１５４】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１５５】
実施例５
実施例１において、長鎖分岐を有するポリプロピレンの添加量を１０重量％、ポリジシクロペンタジエンの添加量を５重量％とした以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例５とした。
【０１５６】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１５７】
実施例６
トルートン比が５０の長鎖分岐を有するポリプロピレン（ＭＦＲ：３ｇ／１０分、ｍｍｍｍ：９７％、ＩＩ：９６．５％）８５重量％に、延伸助剤として、極性基を実質的に含まないテルペン樹脂である、Ｔｇ７５℃、臭素価４ｃｇ／ｇ、水添率９９％のβ−ピネンとＴｇ７５℃、臭素価３ｃｇ／ｇ、水添率９９％の水添β−ジペンテンの混合物を１５重量％添加混合した樹脂組成１００重量部に、架橋有機粒子として平均粒径１μｍのポリスチレン系重合体の架橋粒子（架橋ＰＳ）を０．１５重量部添加し、帯電防止剤としてグリセリン脂肪酸エステルとアルキルジエタノールアミン脂肪酸エステルを１：１の割合に混合して０．８重量部添加し、二軸押出機に供給して２６０℃でガット状に押出し、２０℃の水槽に通して冷却してチップカッターで３ｍｍ長にカットした後、１００℃で２時間乾燥したチップを一軸押出機に供給して２７０℃で溶融させ、濾過フィルターを経た後にスリット状口金から押出し、３０℃の金属ドラムに巻き付けてシート状に成形した。
【０１５８】
このシートを１３２℃に保たれたロールに通して予熱し、１３７℃に保ち周速差を設けたロール間に通し、長手方向に８倍延伸して直ちに室温に冷却する。引き続きこの延伸フィルムをテンターに導入して１６２℃で予熱し、１６０℃で幅方向に８倍に延伸し、次いで幅方向に８％の弛緩を与えつつ、１６０℃で熱固定をした後、冷却して巻き取った厚さ１５μｍの二軸延伸ポリプロピレンフィルムを得た。
【０１５９】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１６０】
実施例７
実施例６において、トルートン比が１２の公知のポリプロピレン（ＭＦＲ：２．３ｇ／１０分、ｍｍｍｍ：９２％、ＩＩ：９６％）に、トルートン比が５０の長鎖分岐を有するポリプロピレン（ＭＦＲ：３ｇ／１０分、ｍｍｍｍ：９７％、ＩＩ：９６．５％）を５重量％の比率で添加混合したポリプロピレン８０重量％に、ポリプロピレンに相溶して、延伸助剤として、極性基を実質的に含まない石油樹脂である、Ｔｇ８０℃、臭素価３ｃｇ／ｇ、水添率９９％のポリジシクロペンタジエンを２０重量％混合し、長手方向に１１倍、幅方向に６倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例７とした。
【０１６１】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１６２】
実施例８
実施例３において、トルートン比が４０の長鎖分岐を有するポリプロピレン（ＭＦＲ：２．０ｇ／１０分、ｍｍｍｍ：９５％、ＩＩ：９６％）を１５重量％の比率で添加したポリプロピレンを用いた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例８とした。
【０１６３】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１６４】
実施例９
実施例８において、長鎖分岐を有するポリプロピレンの混合比率を１０重量％とした以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例９とした。
【０１６５】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１６６】
実施例１０
実施例３において、トルートン比が６０の長鎖分岐を有するポリプロピレン（ＭＦＲ：２．１ｇ／１０分、ｍｍｍｍ：９４％、ＩＩ：９５．５％）を５重量％の比率で添加混合したポリプロピレンを用いた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例１０とした。
【０１６７】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１６８】
実施例１１
実施例１において、長鎖分岐を有するポリプロピレンを３０重量％の比率で添加混合し、長手方向に１０倍、幅方向に７倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例１１とした。
【０１６９】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１７０】
実施例１２
実施例１において、トルートン比が１０の公知のポリプロピレン（ＭＦＲ：３．１ｇ／１０分、ｍｍｍｍ：９８％、ＩＩ：９９％）に、長鎖分岐を有するポリプロピレンを５重量％の比率で添加混合したポリプロピレンを用いて、長手方向に１０倍、幅方向に８倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例１２とした。
【０１７１】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１７２】
実施例１３
実施例５において、トルートン比が１１の公知のポリプロピレン（ＭＦＲ：２．５ｇ／１０分、ｍｍｍｍ：９５．５％、ＩＩ：９６％）に長鎖分岐を有するポリプロピレンを１０重量％の比率で添加混合したポリプロピレンを用いて、長手方向に９倍、幅方向に８倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例１３とした。
【０１７３】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１７４】
実施例１４
実施例４において、長手方向の延伸を２段に分けて、１３５℃で予熱した後、１段目で１３７℃にて１．５倍、２段目で１４２℃にて５．３倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを実施例１４とした。
【０１７５】
結果を表１、２に示す。得られたフィルムは、長手方向のヤング率が高く、抗張力性に優れるとともに防湿性、寸法安定性、二次加工性に優れていた。
【０１７６】
【表１】

【０１７７】
【表２】

【０１７８】
比較例１
実施例１において、トルートン比が１２の公知のポリプロピレン（ＭＦＲ：２．３ｇ／１０分、ｍｍｍｍ：９２％、ＩＩ：９６％）単体を用いて長手方向に５倍、幅方向に１０倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例１とした。
【０１７９】
結果を表３、４に示す。得られたフィルムは、長手方向のヤング率が低く、抗張力性が不十分であり、防湿性、二次加工性に劣っていた。
【０１８０】
比較例２
比較例１において、縦方向の延伸倍率を７倍に上げた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例２とした。
【０１８１】
結果を表３、４に示す。横延伸の際に破れが多発したため、満足なフィルムが得られなかった。
【０１８２】
比較例３
比較例１において、トルートン比が１０の公知のポリプロピレン（ＭＦＲ：３ｇ／１０分、ｍｍｍｍ：９７．５％、ＩＩ：９９％）単体を用いた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例３とした。
【０１８３】
結果を表３、４に示す。得られたフィルムは、溶融状態から冷却ドラムに巻き付ける際にエッジがまくれ上がるため、縦延伸でシートがしばしば切れた。また、横延伸の際に破れが散発し、全体として製膜性が悪く、工業的に生産できないフィルムであった。
【０１８４】
比較例４
比較例１において、トルートン比が８の公知のポリプロピレン（ＭＦＲ：６ｇ／１０分、ｍｍｍｍ：９９．８％、ＩＩ：９９．５％）単体を用いた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例４とした。
【０１８５】
結果を表３、４に示す。横延伸の際に破れが多発したため、満足なフィルムが得られなかった。
【０１８６】
比較例５
実施例６において、長鎖分岐を有するポリプロピレン単体を用いた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例５とした。
【０１８７】
結果を表３、４に示す。得られたフィルムは、長手方向のヤング率が低く、抗張力性が不十分となり、二次加工性に劣っていた。
【０１８８】
比較例６
実施例５において、極性基を実質的に含まない石油樹脂の代わりに、ポリプロピレンとの相溶性が悪い極性基としてカルボキシル基を含んだＴｇ３９℃で、臭素価１５ｃｇ／ｇの未水添のガムロジンを用い、長手方向に５倍、幅方向に１１倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例６とした。
【０１８９】
結果を表３、４に示す。得られたフィルムは、ポリプロピレンとの相溶性が悪いガムロジンを添加しており、ガムロジンのＴｇが低く、臭素価が高く、極性基を持っているために、長手方向と幅方向のヤング率が低く、剛性が不十分であった。また、長手方向のヤング率が低く、抗張力性が不十分であり、二次加工性に劣っていた。
【０１９０】
比較例７
比較例１において、長手方向に８倍延伸し、冷却後そのまま巻き取った厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例７とした。
【０１９１】
結果を表３、４に示す。得られたフィルムは、長手方向に裂けやすく、フィルムのハンドリング性に著しく劣っていることから、二次加工性に劣っていた。
【０１９２】
比較例８
比較例１において、ポリプロピレン９７重量％に、延伸助剤として、極性基を実質的に含まないテルペン樹脂である、Ｔｇ７５℃、臭素価４ｃｇ／ｇ、水添率９９％のβ−ピネンを３重量％添加混合した樹脂組成を用い、長手方向に５倍、幅方向に９倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例８とした。
【０１９３】
結果を表３、４に示す。得られたフィルムは、長手方向のヤング率が低く、抗張力性が不十分であり、二次加工性にも劣っていた。
【０１９４】
比較例９
比較例８において、長手方向に７倍、幅方向に８倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例９とした。
【０１９５】
結果を表３、４に示す。横延伸の際に破れが散発し、十分な長さのフィルムを採取することができず、工業的に生産できないフィルムであった。
【０１９６】
比較例１０
比較例８において、長手方向の延伸倍率をさらに８倍に上げた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例１６とした。
【０１９７】
結果を表３、４に示す。横延伸の際に破れが多発したため、満足なフィルムが得られなかった。
【０１９８】
比較例１１
比較例８において、β−ピネンの混合量を１０重量とした以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムの比較例１１とした。
【０１９９】
結果を表３、４に示す。得られたフィルムは、８０℃での長手方向のヤング率が低く、抗張力性が不十分であり、寸法安定性、二次加工性に劣っていた。
【０２００】
比較例１２
比較例１１において、長手方向に８倍、幅方向に７倍延伸した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例１１とした。
【０２０１】
結果を表３、４に示す。横延伸の際に破れが散発し、十分な長さのフィルムを採取することができず、工業的に生産できないフィルムであった。
【０２０２】
比較例１３
比較例１１において、長手方向の延伸倍率をさらに９倍に上げた以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例１３とした。
【０２０３】
結果を表３、４に示す。横延伸の際に破れが多発したため、満足なフィルムが得られなかった。
【０２０４】
比較例１４
比較例１において、ポリプロピレン１００重量部に、結晶核剤としてリン酸２，２−メチレンビス（４，６−ジ−第３−ブチルフェニル）ナトリウムを０．２重量部添加した以外は同様の条件で作製した厚さ１５μｍの二軸延伸ポリプロピレンフィルムを比較例１４とした。
【０２０５】
結果を表３、４に示す。得られたフィルムは、長手方向のヤング率が低く、抗張力性が不十分であり、二次加工性に劣っていた。また、比較例１に比べてフィッシュアイによる欠点が増大した。
【０２０６】
【表３】

【０２０７】
【表４】

【０２０８】
表１〜４より、本発明の二軸延伸ポリプロピレンフィルムが、トルートン比が３０以上のポリプロピレンを含むか、もしくはトルートン比が１６以上のポリプロピレンからなり、かつ延伸助剤の１種以上を含むことにより、抗張力性に優れるとともに寸法安定性、防湿性に優れたフィルムとすることができた。また、このような優れた特性を有するフィルムを汎用の縦−横逐次二軸延伸機を用いて、破れなどの工程不良なく、安定して製膜することができた。
【０２０９】
【発明の効果】
本発明の二軸延伸ポリプロピレンフィルムは、従来の二軸延伸ポリプロピレンフィルムに比較して長手方向の剛性が高いことから、フィルム加工時の抗張力性に優れるとともに、長手方向と幅方向の剛性がバランス化していることから、フィルムを薄膜化しても十分な腰を有する。これより、本発明の二軸延伸ポリプロピレンフィルムは、フィルムのハンドリング性に優れるだけでなく、印刷、ラミネート、コーティング、蒸着、製袋などのフィルム加工時に、加工張力に対する優れた抗張力性を示し、印刷ピッチずれ、フィルムの伸び、シワ入り、膜割れ（クラック）などのベースフィルム起因のトラブルを解消することができる。
【０２１０】
また、従来の汎用の二軸延伸ポリプロピレンフィルムより薄くしても寸法安定性、防湿性に優れることから、従来より薄くしても寸法安定性、防湿性などのその他の特性を損なうことなく、加工特性を保持することができる。かつ、既存の縦−横逐次二軸延伸機を用いることから、大きな設備投資を必要とせず、上記特性を持ったフィルムを低コストで安定製造することができる。
【０２１１】
さらに、本発明の二軸延伸ポリプロピレンフィルムは、他のフィルムと複合化して構成体に加工して用いるような場合でも、該構成体の二次加工性やガスバリア性能を向上させることができる。また、一般特性を損なうことなく、本発明のフィルム、もしくは本発明のフィルムと複合化する他のフィルムを適宜薄膜化できるため、廃棄物や資源を削減することができる。
【０２１２】
以上のことから、本発明の二軸延伸ポリプロピレンフィルムは、包装用途、工業用途などに好ましく用いることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a biaxially oriented polypropylene film suitable for a wide range of uses such as packaging and industrial uses.
[0002]
[Prior art]
Due to social demands for reducing waste and resources, there is a growing expectation for thinner materials, especially for packaging applications. At present, for example, a 20 μm biaxially stretched polypropylene film or the like is used for packaging, and most of them are manufactured by a general-purpose longitudinal-lateral sequential biaxial stretching method. The general-purpose vertical-horizontal sequential biaxial stretching method referred to here is a method in which a polymer is melted by an extruder, passed through a filter, extruded from a slit die, wound around a metal drum, and cooled and solidified into a sheet. A stretched film is obtained, the unstretched film is stretched in the longitudinal direction between rolls provided with a difference in peripheral speed, then guided in a tenter, stretched in the width direction, heat-fixed, and wound up after cooling to obtain a stretched film. This is a typical method for producing a biaxially stretched polypropylene film.
[0003]
If the same performance and processing suitability can be obtained with a biaxially oriented polypropylene film of 15 μm as compared to the biaxially oriented polypropylene film of 20 μm exemplified here, it is possible to reduce 25% of dust and resources.
[0004]
In order to satisfy such requirements, it is necessary to first strengthen the biaxially stretched polypropylene film to suppress the elongation with respect to the tension in the processing step. At this time, since the tension in the processing step is applied in the longitudinal direction of the film, it is necessary to strengthen the biaxially oriented polypropylene film mainly in the longitudinal direction.
[0005]
In general, when the polypropylene film is strengthened, the heat shrinkage of the polypropylene film tends to increase. When the dimensional stability of the film at high temperature is deteriorated, the film shrinks during secondary processing such as printing, coating, and laminating, and the commercial value of the film may be extremely reduced. Therefore, it is necessary to suppress the heat shrinkage to approximately the same as or less than a general-purpose biaxially stretched polypropylene film.
[0006]
In order to strengthen a biaxially stretched polypropylene film, a method for obtaining a film strong in the longitudinal direction after stretching in the longitudinal direction and the width direction and then re-stretching in the longitudinal direction is known (for example, Patent Document 1). -3). Furthermore, in order to eliminate the weakness in the width direction of a film strong in the longitudinal direction, a method is disclosed in which a polypropylene sheet having a specific melt crystallization temperature is biaxially stretched and then re-stretched in the longitudinal direction. Reference 4). In addition to the sequential biaxial stretching method, a biaxially stretched polypropylene film that has been strengthened in the longitudinal direction can be produced by a simultaneous longitudinal-horizontal biaxial stretching method (for example, see Non-Patent Document 1 or 2).
[0007]
Regarding the strengthening of a biaxially stretched polypropylene film, in addition to the above-described studies from the viewpoint of the production process, studies from the viewpoint of raw materials by modifying polypropylene have been conventionally performed. For example, a biaxially-stretched polypropylene film having excellent rigidity and moisture-proof properties can be obtained by modifying the crystallinity of polypropylene, for example, (for example, see Patent Document 5). Further, by adding a petroleum resin, a terpene resin, or the like to polypropylene, a biaxially stretched polypropylene film having improved film forming properties and excellent rigidity and moisture resistance can be obtained (for example, see Patent Document 6). .). Further, biaxially stretched polypropylene films obtained by adding a petroleum resin, a terpene resin, or the like to these highly crystalline polypropylenes are also known (for example, see Patent Documents 7 to 10).
[0008]
[Patent Document 1]
Japanese Patent Publication No. 41-21790
[0009]
[Patent Document 2]
Japanese Patent Publication No. 45-37879
[0010]
[Patent Document 3]
JP-B-49-18628
[0011]
[Patent Document 4]
JP-A-56-51329
[0012]
[Patent Document 5]
JP 2001-40111 A
[0013]
[Patent Document 6]
Japanese Patent No. 1733605
[0014]
[Patent Document 7]
Japanese Patent No. 3077482
[0015]
[Patent Document 8]
Japanese Patent Publication No. 11-507605
[0016]
[Patent Document 9]
JP-T-2000-509884
[0017]
[Patent Document 10]
JP-A-2002-128913
[0018]
[Non-patent document 1]
Nishiyama, "Molding", 2002, Vol. 14, No. 14, p. 18-24
[0019]
[Non-patent document 2]
Breil, "TAPPI Proceedings. Polymers, Laminations & Coatings Conference", (USA), 1999, p. 727-745
[0020]
[Problems to be solved by the invention]
However, it has been difficult to obtain a biaxially stretched polypropylene film strengthened in the longitudinal direction by a general-purpose longitudinal-transverse sequential biaxial stretching method. That is, in the longitudinal-horizontal sequential biaxial stretching method, the temperature needs to be in a semi-molten state in order to transversely stretch the oriented crystal generated in the longitudinal stretching. For this reason, after the transverse stretching, most of the crystals rearranged in the width direction, and only a biaxially stretched polypropylene film having rigidity largely biased in the width direction was obtained.
[0021]
In addition, the above-described method of re-stretching in the longitudinal direction and the simultaneous biaxial stretching method have a problem that the steps are complicated and equipment costs are increased. Further, the thermal dimensional stability mainly in the longitudinal direction may be deteriorated, and the rigidity in the longitudinal direction may be insufficient.
[0022]
Furthermore, when polypropylene having high crystallinity is used, there is a problem that film forming properties are inferior to conventional polypropylene, tears occur during biaxial stretching, and the process becomes unstable. Also, when a highly crystalline polypropylene film is formed by a general-purpose longitudinal-lateral sequential biaxial stretching method, the above-described crystal rearrangement actually increases the rigidity mainly in the width direction and the longitudinal direction. The rigidity was insufficient. In addition, a biaxially oriented polypropylene film obtained by adding a petroleum resin or a terpene resin to polypropylene has a problem that the heat shrinkage of the film is high, the thermal dimensional stability is poor, and the rigidity of the film is reduced at a high temperature, Due to the above-described crystal rearrangement, the rigidity in the longitudinal direction was also insufficient. In addition, biaxially stretched polypropylene film obtained by adding petroleum resin or terpene resin to polypropylene having high crystallinity also has a problem of tearing, film forming property is insufficient, and rigidity in the longitudinal direction due to the above-described crystal rearrangement. Was also inadequate.
[0023]
As described above, the conventional biaxially stretched polypropylene film has insufficient rigidity in the longitudinal direction. Therefore, in the film processing steps such as printing, laminating, coating, vapor deposition, bag making, and releasing, the printing pitch shift, the film elongation / Problems such as shrinkage, wrinkling, and film cracking may occur. For example, when a vapor-deposited film is taken as an example, a general-purpose biaxially stretched polypropylene film is weak in the longitudinal direction. Therefore, when a metal vapor-deposited film is used, the vapor-deposited film is cracked in various film processing steps such as printing and bag making. Cracks), and as a result, there is a problem that the gas barrier property is deteriorated.
[0024]
An object of the present invention is to solve the above problems, and provides a biaxially oriented polypropylene film having a high rigidity in the longitudinal direction of the film by a general-purpose longitudinal-lateral sequential biaxial stretching method generally performed conventionally. It is to be. Another object of the present invention is to provide a biaxially stretched polypropylene film having a heat shrinkage, a moisture-proof property, and the like that are substantially equal to or superior to those of a general-purpose biaxially stretched polypropylene film, and have the same performance as a conventional film even when thinned.
[0025]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that the above problem can be mainly solved by the following constitution.
[0026]
That is, the biaxially stretched polypropylene film of the present invention mainly includes polypropylene having a trouton ratio of 30 or more, and is characterized in that one or more stretching aids are mixed.
Further, as another configuration, the biaxially stretched polypropylene film of the present invention is characterized in that one or more stretching aids are mainly mixed with polypropylene having a trouton ratio of 16 or more.
Further, as another configuration, the biaxially stretched polypropylene film of the present invention mainly includes polypropylene having a long-chain branch, and is characterized in that one or more stretching aids are mixed.
Further, as a preferred embodiment, the stretching aid is a petroleum resin substantially free of a polar group and / or a terpene resin substantially free of a polar group, and the Young's modulus in the longitudinal direction (Y_MD) Is not less than 2.5 GPa at 25 ° C., the mesopentad fraction (mmmm) of polypropylene is 90 to 99.5%, and the heat shrinkage in the longitudinal direction at 120 ° C. is 5% or less. And the Young's modulus in the longitudinal direction (Y_MD) And the Young's modulus in the width direction (Y_TD) And the m value represented by the following equation (1)
m = Y_MD/ (Y_MD+ Y_TD(1)
Is 0.4 to 0.7 at 25 ° C., the water vapor permeability is 1.5 g / m 2 /d/0.1 mm or less, and the crystallization temperature (Tmc) of polypropylene is 110 ° C. or more. A biaxially stretched polypropylene film, characterized in that:
It is.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
The biaxially oriented polypropylene film of the present invention contains polypropylene having a trouton ratio of 30 or more.
[0028]
The Trouton ratio can be obtained by performing a measurement according to Cogswell's theory [Polymer Engineering Science, 12, 64 (1972)] using the inflow pressure loss method. The Trouton ratio here means 230 ° C. and a strain rate of 60 S obtained from an extensional viscosity-elongational strain rate curve and a shear viscosity-shear strain rate curve approximated by an exponential function.^-1Is the ratio of the extensional viscosity to the shear viscosity at
[0029]
The biaxially oriented polypropylene film of the present invention is a biaxially oriented polypropylene having a high rigidity in the longitudinal direction, which has been difficult in general-purpose longitudinal-lateral sequential biaxial stretching method, by including a polypropylene having a trouton ratio of 30 or more. Films can be manufactured. That is, the polypropylene having a trouton ratio of 30 or more suppresses rearrangement of the longitudinally oriented crystals in the width direction during the transverse stretching.
[0030]
The trouton ratio of the polypropylene contained in the biaxially oriented polypropylene film of the present invention is preferably as high as possible to some extent, but if it is too high, the film-forming properties may deteriorate or the surface haze may deteriorate. The Trouton ratio of the polypropylene contained in the biaxially oriented polypropylene film of the present invention is more preferably 35 or more, and even more preferably in the range of 40 to 100.
[0031]
As a method for obtaining a polypropylene having a trouton ratio of 30 or more as described above, a method of blending a polypropylene containing a large amount of a high molecular weight component, a method of blending an oligomer or polymer having a branched structure, and a method described in JP-A-62-121704 A method of introducing a long-chain branching structure into a polypropylene molecule as described, or a melt tension and an intrinsic viscosity, a crystallization temperature and a melting point without introducing a long-chain branch as described in Japanese Patent No. 2869606. Satisfies a specific relationship with each other, and a method of producing a linear crystalline polypropylene having a boiling xylene extraction residual ratio in a specific range is preferably used.
[0032]
For the biaxially oriented polypropylene film of the present invention, among these polypropylenes, it is particularly preferable to use a polypropylene having a long-chain branch introduced into the molecular chain skeleton.
[0033]
Here, the polypropylene having a long-chain branch refers to a polypropylene having a branched polypropylene chain in a polypropylene main chain skeleton. Since the biaxially stretched polypropylene film of the present invention contains polypropylene having long-chain branching, it is possible to suppress rearrangement of the longitudinally-oriented crystals in the width direction during transverse stretching, so that the rigidity in the longitudinal direction is further increased. be able to. This is because the long-chain branch acts as a tie molecule for pseudo-crosslinking the vertically oriented crystal, and the stretching stress is transmitted uniformly throughout the system during transverse stretching, thereby suppressing the rearrangement of the vertically oriented crystal in the width direction. It is inferred. The longer the branched polypropylene chain of the polypropylene having long chain branching, the higher the effect of suppressing the rearrangement of the longitudinally oriented crystal, and preferably has the same length as the polypropylene main chain. In addition, it is preferable that one or more long-chain branches are introduced into one polypropylene main chain from the viewpoint of suppressing rearrangement of longitudinally-oriented crystals, and more preferably two or more.
[0034]
The weight average molecular weight (Mw) of the polypropylene having a long chain branch is 10 × 10⁴It is preferable that it is above. When Mw is less than the above range, the above-described effect of suppressing the rearrangement of the vertically oriented crystals may be insufficient. There is no particular upper limit on Mw as long as the effects of the present invention can be achieved.⁴The following is preferred. Mw is preferably 15 × 10⁴Above, more preferably 20 × 10⁴That is all. The weight average molecular weight of the polypropylene having a long chain branch is described in M.P. L. It is measured by the method described by McConnell in American Laboratory, May, 63-75 (1978), ie, low angle laser light scattering photometry.
[0035]
Specific examples of the polypropylene having a long chain branch include polypropylene manufactured by Basell (type name: PF-814, etc.), polypropylene manufactured by Borealis (type name: WB130HMS, etc.), polypropylene manufactured by Dow (type name: D201, etc.), and the like. Is mentioned.
[0036]
An index value indicating the degree of long-chain branching of polypropylene includes a branching index g represented by the following formula.
[0037]
g = [η]_LB/ [Η]_Lin
Where [η]_LBIs the intrinsic viscosity of polypropylene having long chain branches, [η]_LinIs the intrinsic viscosity of a linear crystalline polypropylene having substantially the same weight average molecular weight as a polypropylene having a long chain branch. The intrinsic viscosity shown here is measured at 135 ° C. by a known method for a sample dissolved in tetralin. The weight-average molecular weight at the time of measuring the g-value was determined by M.P. L. It is measured by the method described by McConnell in American Laboratory, May, 63-75 (1978), ie, low angle laser light scattering photometry.
[0038]
The polypropylene having a trouton ratio of 30 or more contained in the biaxially oriented polypropylene film of the present invention preferably has a branching index g of 0.95 or less. If the branching index g exceeds the above range, the effect of adding the polypropylene having a trouton ratio of 30 or more may be reduced, and the Young's modulus in the longitudinal direction of the film may be insufficient. The branching index g of polypropylene having a trouton ratio of 30 or more is more preferably 0.9 or less.
[0039]
The mixing amount of the polypropylene having a trouton ratio of 30 or more contained in the biaxially oriented polypropylene film of the present invention is not particularly limited, but is preferably 1 to 60% by weight, and the effect is seen even when a small amount is added. is there. If the mixing amount is less than the above range, the transverse stretching property may be deteriorated, or the effect of improving the rigidity in the longitudinal direction may be reduced. If the mixing amount is more than the above range, the longitudinal stretching property may be deteriorated or the impact resistance of the film may be reduced. , Transparency and the like may be deteriorated. The mixing amount of the polypropylene having a troutone ratio of 30 or more is more preferably 2 to 50% by weight, and still more preferably 3 to 40% by weight.
[0040]
Another configuration of the present invention is that the polypropylene used for the biaxially oriented polypropylene film of the present invention has a Trouton ratio of 16 or more.
[0041]
The biaxially oriented polypropylene film of the present invention is made of polypropylene having a trouton ratio of 16 or more. Films can be manufactured.
[0042]
The higher the Trouton ratio of the polypropylene used in the biaxially oriented polypropylene film of the present invention, the better, but if it is too high, the film-forming properties may deteriorate or the surface haze may worsen. The Trouton ratio of the polypropylene used for the biaxially oriented polypropylene film of the present invention is more preferably 18 or more, further preferably in the range of 20 to 100, and most preferably in the range of 20 to 80. These can be adjusted, for example, by adding a polypropylene having a long chain branch as described below, and the rigidity in the longitudinal direction can be further improved.
[0043]
The above-mentioned polypropylene having a trouton ratio of 16 or more is, for example, a mixture of a polypropylene having a long-chain branch and a known general-purpose polypropylene, or a copolymer of a long-chain branch component in the main chain skeleton of the general-purpose polypropylene, such as graft polymerization. Obtained by introduction. That is, the polypropylene having such a long-chain branch can suppress rearrangement of the longitudinally-oriented crystals in the width direction during the transverse stretching.
[0044]
The polypropylene used for the biaxially stretched polypropylene film of the present invention is not particularly limited as long as it has a trouton ratio of 16 or more. For example, it is preferable to contain polypropylene having the following properties.
[0045]
That is, it is preferable to include polypropylene having a trouton ratio of 30 or more and to make the trouton ratio 16 or more. Polypropylene having a troutone ratio of 30 or more can be obtained, for example, by mixing a polypropylene having a long-chain branch in the main chain skeleton and a general-purpose polypropylene, or introducing a long-chain branching component into the main chain skeleton of the general-purpose polypropylene by copolymerization or graft polymerization. It is obtained by doing.
[0046]
Although the molecular structure of conventional general-purpose polypropylene is a linear structure, the polypropylene used for the biaxially stretched polypropylene film of the present invention is mixed with a polypropylene having such a long-chain branch to form a vertically oriented crystal during transverse stretching. Rearrangement in the width direction can be suppressed. This is because the long-chain branch acts as a tie molecule for pseudo-crosslinking the vertically oriented crystal, and the stretching stress is transmitted uniformly throughout the system during transverse stretching, thereby suppressing the rearrangement of the vertically oriented crystal in the width direction. It is inferred.
[0047]
In this case, the troutone ratio of the polypropylene having a long chain branch to be mixed is more preferably 35 or more, and still more preferably 40 to 100.
[0048]
The crystallization temperature (Tmc) of the polypropylene used for the biaxially oriented polypropylene film of the present invention is preferably 110 ° C. or higher. By setting Tmc within the above range, the spherulite size can be reduced when an unstretched sheet is obtained by cooling from a molten state, and the crystal orientation in the longitudinal direction after longitudinal stretching can be increased, and the film formation stability can be improved. And the transparency may be enhanced after biaxial stretching. If the Tmc of the polypropylene used is less than the above range, the transparency of the film after biaxial stretching is deteriorated, the crystal orientation in the longitudinal direction after longitudinal stretching does not increase, and the rigidity in the longitudinal direction after biaxial stretching is not sufficient. May be sufficient. Although there is no upper limit on Tmc as long as the effects of the present invention are exhibited, it is preferably 140 ° C. or lower, more preferably 135 ° C. or lower, for example, from the viewpoint of stable film formation. Tmc is more preferably at least 112 ° C, still more preferably at least 115 ° C, most preferably at least 118 ° C.
[0049]
The melt flow rate (MFR) of the polypropylene used for the biaxially oriented polypropylene film of the present invention is preferably 1 to 30 g / 10 minutes from the viewpoint of film forming properties. When the MFR is less than the above range, the filtration pressure increases during melt extrusion, it takes a long time to replace the extruded raw material, it becomes difficult to form a film having a uniform thickness, and the film forming property is deteriorated. Problem may occur. If the MFR exceeds the above range, there may be a problem that the thickness unevenness of the formed film becomes large. MFR is more preferably 1 to 20 g / 10 min.
[0050]
The mesopentad fraction (mmmm) of the polypropylene used for the biaxially oriented polypropylene film of the present invention is preferably 90 to 99.5%, more preferably 92 to 99.5%. Here, mmmm is an index that directly reflects the isotactic three-dimensional structure of polypropylene. By setting the mmmm in the above range, a film having excellent dimensional stability and significantly improved heat resistance, rigidity, moisture resistance, chemical resistance, etc. can be stably manufactured, so that printing, coating, vapor deposition, bag making, In a film processing step such as lamination or release, a film having high secondary workability can be provided. When mmmm is less than the above range, the stiffness when formed into a film is reduced, and the heat shrinkage tends to increase, so that secondary processing properties such as printing, coating, vapor deposition, bag making, laminating, and releasing are reduced. In some cases, the water vapor transmission rate may increase. The rigidity, dimensional stability, and moisture resistance tend to improve as the mmmm increases, but if it exceeds the above range, the film-forming properties may deteriorate. mmmm is more preferably 93 to 99%, most preferably 94 to 98.5%.
[0051]
The polypropylene used for the biaxially oriented polypropylene film of the present invention preferably has an isotactic index (II) of 92 to 99.8%. If the II is less than the above range, problems such as a decrease in stiffness when formed into a film, an increase in heat shrinkage, and an increase in water vapor transmission rate may occur, and printing, coating, vapor deposition, and bag making. In some cases, secondary workability such as lamination and release may be reduced. The rigidity, dimensional stability, and moisture resistance tend to be improved as the II increases, but if it exceeds the above range, the film-forming properties may deteriorate. II is more preferably 94 to 99.5%.
[0052]
The polypropylene used for the biaxially oriented polypropylene film of the present invention is, from the viewpoint of economy, etc., within the range not impairing the characteristics of the present invention, and a scrap film generated when the biaxially oriented polypropylene film of the present invention is produced, and the like. A scrap film generated during the production of the above film and other resins may be used as a blend. In this case, it is necessary that the blended polypropylene has a trouton ratio of 16 or more from the viewpoint of improving the rigidity in the longitudinal direction.
[0053]
The polypropylene used for the biaxially oriented polypropylene film of the present invention is mainly composed of a propylene homopolymer, but a monomer component of polypropylene and another unsaturated hydrocarbon is copolymerized within a range not to impair the purpose of the present invention. It may be a polymer, a polymer in which propylene and a monomer component other than propylene are copolymerized may be blended, or a (co) polymer of an unsaturated hydrocarbon monomer component other than propylene may be blended. Coalescing may be blended. Examples of such a copolymer component or a monomer component constituting the blend include ethylene, propylene (in the case of a copolymerized blend), 1-butene, 1-pentene, 3-methylpentene-1,3 -Methylbutene-1, 1-hexene, 4-methylpentene-1, 5-ethylhexene-1, 1-octene, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, 5-methyl -2-norbornene and the like.
[0054]
Here, the characteristic values of polypropylene such as the above-described trouton ratio, branching index g, MFR, mmmm, and II are desirably determined using raw material chips before film formation. After extracting the film with n-heptane at a temperature of 60 ° C. or less for about 2 hours, removing impurities and additives, and then vacuum-drying the film at 130 ° C. for 2 hours or more, measurement can be performed using a sample.
[0055]
Next, the biaxially stretched polypropylene film of the present invention needs to contain a stretching aid from the viewpoints of strengthening, improving moisture resistance, and improving film forming properties. The stretching aid referred to here is an additive that is added to the polypropylene used for the biaxially stretched polypropylene film of the present invention, and enables stable and higher-magnification stretching as compared with the case where it is not added. . If such a stretching aid is not mixed, the effect of suppressing rearrangement of the longitudinally-oriented crystals in the width direction by the polypropylene having long chain branches cannot be sufficiently exerted, and the film-forming properties and the moisture-proof properties are also poor.
[0056]
The stretching aid of the present invention is preferably a resin having high compatibility with polypropylene, and the glass transition point temperature (hereinafter sometimes referred to as Tg) is preferably 60 ° C. or higher. When Tg is 60 ° C. or higher, it is preferable because the effect of improving the moisture resistance and rigidity of the film can be sufficiently obtained. Further, the upper limit of Tg is not particularly limited as long as the effects of the present invention are exerted, but if it is 120 ° C. or lower, excellent compatibility with polypropylene, stretchability of a film, moisture-proof property and the like can be obtained. preferable.
[0057]
As the stretching aid of the present invention, at least one kind of a petroleum resin substantially free of a polar group and / or a terpene resin substantially free of a polar group can be used for high-magnification stretching, strengthening, and improvement in moisture resistance. It is preferably used from the viewpoint.
[0058]
Here, the petroleum resin substantially free of a polar group is a petroleum resin having no polar group such as a hydroxyl group, a carboxyl group, a halogen group, a sulfone group or a modified form thereof, and specifically, a petroleum resin. It is a resin based on cyclopentadiene or higher olefin hydrocarbons, which are based on unsaturated hydrocarbons.
[0059]
Further, the Tg of the petroleum resin substantially free of such a polar group is preferably 60 ° C. or higher. If Tg is less than the above range, the effect of improving rigidity may be reduced. Although the upper limit of Tg is not particularly limited as long as the effects of the present invention are exhibited, it is preferably 120 ° C. or lower from the viewpoints of compatibility with polypropylene, stretchability of the film, moisture resistance and the like.
[0060]
Hydrogenated (hereinafter sometimes referred to as hydrogenated) petroleum resins obtained by adding hydrogen to such petroleum resins and setting the hydrogenation rate to 90% or more, preferably 99% or more, are particularly preferably used. Representative hydrogenated petroleum resins include, for example, alicyclic petroleum resins such as polydicyclopentadiene having a Tg of 70 ° C. or more and a hydrogenation rate of 99% or more.
[0061]
Further, the terpene resin substantially free of a polar group is a terpene resin having no polar group consisting of a hydroxyl group, an aldehyde group, a ketone group, a carboxyl group, a halogen group, a sulfone group or a modified form thereof, that is, ( C₅H₈And n) a hydrocarbon having a composition of n and a modified compound derived therefrom. Here, n is a natural number of about 2 to 20.
[0062]
Terpene resins are sometimes called terpenoids, and typical compounds include pinene, dipentene, karen, myrcene, ocimene, limonene, terpinolene, terpinene, sabinene, tricyclene, bisabolene, zingiperene, santalen, camphoren, millen, and totalen. In the case of the biaxially stretched polypropylene film of the present invention, hydrogen is preferably added, and the hydrogenation ratio is preferably 90% or more, and particularly preferably 99% or more. Among them, hydrogenated β-pinene, hydrogenated β-dipentene and the like are particularly preferably used.
[0063]
The Tg of the terpene resin substantially free of such a polar group is preferably 60 ° C. or higher. If Tg is less than the above range, the effect of improving rigidity may be reduced. Although the upper limit of Tg is not particularly limited as long as the effects of the present invention are exhibited, it is preferably 120 ° C. or lower from the viewpoints of compatibility with polypropylene, stretchability of the film, moisture resistance and the like.
[0064]
The bromine value of the petroleum resin or terpene resin is preferably 10 or less, more preferably 5 or less, and particularly preferably 1 or less.
[0065]
The addition amount of the above-mentioned stretching aid is not particularly limited as long as the effect is exhibited, but it is preferable that the total amount of the petroleum resin and the terpene resin is 0.1 to 30% by weight. If the amount of the resin is less than the above range, the effect of improving the stretchability and the rigidity in the longitudinal direction may be reduced, or the transparency may be deteriorated. If it exceeds the above range, the thermal dimensional stability may deteriorate, the additive may bleed out to the surface layer of the film to deteriorate the slipperiness, or the films may be blocked. The mixing amount of the additive is more preferably 1 to 20% by weight, and further preferably 2 to 15% by weight, in total with the addition amount of the petroleum resin and the terpene resin.
[0066]
When a petroleum resin and / or a terpene resin containing a polar group is used as a stretching aid, voids are easily formed inside the film due to poor compatibility with polypropylene, and the water vapor permeability increases. In addition, the bleed out of the antistatic agent and the lubricant may be deteriorated.
[0067]
Specific examples of such a stretching aid include, for example, “Escolets” (type name: E5300 series, etc.) manufactured by Tonex Corporation, “Clearon” (type name: P-125, etc.) manufactured by Yashara Chemical Co., Ltd., Arakawa Chemical "Alcon" (type name: P-125, etc.) manufactured by Kogyo Co., Ltd., and the like.
[0068]
An antistatic agent is preferably added to the biaxially oriented polypropylene film of the present invention in order to prevent electrostatic damage due to charging of the film. The antistatic agent contained in the biaxially oriented polypropylene film of the present invention is not particularly limited. Examples thereof include an ethylene oxide adduct of a betaine derivative, a quaternary amine compound, an alkyldiethanolamine fatty acid ester, a glycerin fatty acid ester, and a glyceride stearate. Or a mixture thereof.
[0069]
Further, it is preferable to add a lubricant to the biaxially oriented polypropylene film of the present invention, and it is more preferable to use the lubricant together with the above antistatic agent. This is added in order to improve the fluidity and mold release properties of thermoplastic resin expressed in JIS terms during heat molding, and adjusts the frictional force between the processing machine and the film surface or between films. To be added.
[0070]
The lubricant added to the biaxially stretched polypropylene film of the present invention is not particularly limited, and examples thereof include amide compounds such as stearamide, erucamide, erucamide, and oleic amide, and mixtures thereof. .
[0071]
The amount of the antistatic agent to be added to the biaxially oriented polypropylene film of the present invention is preferably 0.3 parts by weight or more, more preferably 0.4 to 100 parts by weight of the polypropylene used. It is in the range of 1.5 parts by weight. Further, the total addition amount of the antistatic agent and the lubricant is more preferably 0.5 to 2.0 parts by weight in terms of antistatic properties and slipperiness.
[0072]
When the biaxially oriented polypropylene film of the present invention is used as a metal-deposited film, a small amount of organic crosslinkable particles or inorganic particles may be added to impart slipperiness and improve workability and winding property. Although acceptable, it is preferable not to add the antistatic agent and the organic lubricant from the viewpoint of improving the adhesion of the metal deposition layer and the gas barrier property.
[0073]
To the biaxially oriented polypropylene film of the present invention, inorganic particles and / or crosslinked organic particles are preferably added and mixed for imparting slipperiness.
[0074]
In the present invention, the inorganic particles are inorganic particles of a metal compound, and are not particularly limited. For example, zeolite, calcium carbonate, magnesium carbonate, alumina, silica, aluminum silicate, kaolin, kaolinite, talc, clay, diatomaceous earth, montmorillonite , Titanium oxide and the like, or a mixture thereof.
[0075]
In the present invention, the crosslinked organic particles are particles obtained by crosslinking a polymer compound using a crosslinking agent. The crosslinked organic particles added to the biaxially stretched polypropylene film of the present invention are not particularly limited. For example, crosslinked particles of a polymethoxysilane compound, crosslinked particles of a polystyrene compound, crosslinked particles of an acrylic compound, polyurethane compounds , A crosslinked particle of a polyester compound, a crosslinked particle of a fluorine compound, or a mixture thereof.
[0076]
The average particle diameter of the inorganic particles and the crosslinked organic particles is preferably 0.5 to 6 μm. If the average particle size is less than the above range, the slipperiness may be deteriorated. If the average particle size is more than the above range, the film surface may be easily damaged when the particles are dropped or the films are rubbed.
[0077]
The addition amount of the inorganic particles and / or the crosslinked organic particles is preferably from 0.02 to 0.5% by weight, more preferably from 0.05 to 0.2% by weight, to prevent blocking. It is preferable in terms of slipperiness and transparency.
[0078]
Further, the biaxially oriented polypropylene film of the present invention may be added with a nucleating agent other than those described above, a heat stabilizer, an antioxidant, and the like, if necessary.
[0079]
For example, as a nucleating agent, a sorbitol type, an organic phosphate metal salt type, an organic carboxylic acid metal salt type, a rosin type nucleating agent, etc. are 0.5% by weight or less, and as a heat stabilizer, 2,6-di- 0.5% by weight or less of tert-butyl-4-methylphenol (BHT) and the like, and tetrakis [methylene- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] as an antioxidant Methane (Irganox 1010) or the like may be added in a range of 0.5% by weight or less.
[0080]
Next, on at least one side of the biaxially oriented polypropylene film of the present invention, additive scattering / bleed-out suppression, coating film / evaporation film easy adhesion, easy printability, heat sealability, print lamination, gloss For various purposes such as imparting slipperiness, reducing haze (imparting transparency), imparting releasability, imparting easy peelability, improving surface hardness, imparting smoothness, improving surface roughness, improving gas barrier properties, imparting hand-cutting properties, etc. Accordingly, it is preferable to appropriately laminate a known polyolefin-based resin and another resin.
[0081]
In this case, the lamination thickness is preferably 0.25 μm or more and 以上 or less of the total thickness of the film. If the lamination thickness is less than 0.25 μm, uniform lamination becomes difficult due to film breakage, etc., and if it exceeds の of the total thickness, the influence of the surface layer on the mechanical properties increases, causing a decrease in Young's modulus. The tensile strength of the film also decreases.
[0082]
In addition, the surface resin to be laminated at this time does not necessarily have to satisfy the scope of the present invention, and examples of the lamination method include coextrusion, inline / offline extrusion lamination, and inline / offline coating, but are limited to any of these. It does not mean that the best method can be selected at any time.
[0083]
By subjecting at least one of the biaxially stretched polypropylene films of the present invention to a corona discharge treatment so as to have a wet tension of 35 mN / m or more, the printability, adhesiveness, antistatic property and bleed out of the lubricant can be obtained. It can be preferably employed to improve the properties. At this time, the atmosphere gas at the time of corona discharge treatment is preferably air, oxygen, nitrogen, carbon dioxide gas, or a mixed system of nitrogen / carbon dioxide gas. From the viewpoint of economy, it is particularly preferable to carry out corona discharge treatment in air. preferable. Further, a flame (flame) treatment, a plasma treatment or the like is also preferable from the viewpoint of improving the surface wetting tension. Although there is no particular upper limit on the wetting tension, excessive surface treatment may deteriorate the surface.
In some cases, it is preferably 60 mN / m or less.
[0084]
The Young's modulus of the biaxially oriented polypropylene film of the present invention in the longitudinal direction at 25 ° C. (Y_MD) Is preferably 2.5 GPa or more. Y at 25 ° C_MDIs less than the above range, the tensile strength at the time of film processing may be insufficient, or the rigidity in the width direction may be higher than that in the longitudinal direction, and the rigidity may be unbalanced. For this reason, the stiffness of the film may be insufficient. At the time of film processing such as printing, laminating, coating, vapor deposition, bag making, releasing, etc., printing pitch deviation, film elongation, wrinkling, film cracking (crack). And the tensile strength of the film may be insufficient. Y at 25 ° C_MDAre the cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, the longitudinal stretching conditions (temperature, magnification, etc.), the crystallinity of the polypropylene used (mesopentad fraction (mmmm), isotactic index (II)) And the like, and the mixing amount of the stretching aid can be controlled. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. Y at 25 ° C_MDIs more preferably 2.7 GPa or more, still more preferably 3.0 GPa or more, and most preferably 3.2 GPa or more.
[0085]
Young's modulus of the biaxially oriented polypropylene film of the present invention in the longitudinal direction at 80 ° C. (Y_MD) Is preferably 0.4 GPa or more. Y at 80 ° C_MDIs less than the above range, the rigidity in the width direction is higher than that in the longitudinal direction, and the rigidity may be unbalanced. For this reason, the stiffness of the film may be insufficient. At the time of film processing such as printing, laminating, coating, vapor deposition, bag making, releasing, etc., printing pitch deviation, film elongation, wrinkling, film cracking (crack). And the tensile strength of the film may be insufficient. Y at 80 ° C_MDAre the cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, longitudinal stretching conditions (temperature, magnification, etc.), the crystallinity of the polypropylene to be used (mesopentad fraction (mmmm), isotactic index (II)) And the like, and the mixing amount of the stretching aid can be controlled. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. Y at 80 ° C_MDIs more preferably at least 0.5 GPa, even more preferably at least 0.6 GPa.
[0086]
The biaxially oriented polypropylene film used in the present invention has a Young's modulus (Y_MD) And the Young's modulus in the width direction (Y_TDM) value represented by)
m = Y_MD/ (Y_MD+ Y_TD(1)
Is preferably 0.4 to 0.7 at 25 ° C. Here, the m value is the ratio of the Young's modulus in the longitudinal direction to the sum of the Young's modulus in the longitudinal direction and the Young's modulus in the width direction of the film. Therefore, a film having an m value of <0.5 has a higher rigidity in the width direction than that in the longitudinal direction, and a film having an m value of 0.5 has substantially balanced rigidity in the longitudinal direction and the width direction. Films with a value> 0.5 have higher rigidity in the longitudinal direction than in the width direction. A biaxially oriented polypropylene film having a rigidity in the longitudinal direction and the width direction substantially balanced by an m value of 0.4 to 0.7, and a biaxially oriented polypropylene having a higher rigidity in the longitudinal direction than the width direction. A film that can be made into a film that is significantly stronger than before, and exhibits excellent handling and processing properties during film processing such as printing, laminating, coating, vapor deposition, bag making, and mold release. Can be stably produced using a general-purpose longitudinal-transverse sequential biaxial stretching method. If the m value at 25 ° C. is less than the above range, the rigidity in the longitudinal direction is inferior compared to the width direction, and the rigidity becomes unbalanced. Insufficient stiffness may cause problems due to the base film such as film cracks, film elongation, wrinkling, printing pitch deviation, etc., which may result in poor handling and workability during film processing. . If the m value at 25 ° C. exceeds the above range, the rigidity in the width direction is significantly reduced as compared with the longitudinal direction, so that the rigidity of the film at the time of thinning becomes insufficient, and the handling property at the time of film processing is insufficient. In some cases, the processability is poor, and the film may be easily torn in the longitudinal direction. The m value at 25 ° C. is determined under film forming conditions (cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, longitudinal and transverse stretching temperatures, magnification, relaxation of the film after longitudinal and transverse stretching, etc.), It can be controlled by the crystallinity (corresponding to the mesopentad fraction (mmmm) and the isotactic index (II)) of the polypropylene used, the mixing amount of the stretching aid, and the like. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The m value at 25 ° C. is more preferably 0.42 to 0.68, further preferably 0.44 to 0.65, and most preferably 0.48 to 0.62. In addition, the biaxially oriented polypropylene film of the present invention may be heated to room temperature or higher during processing steps such as printing and laminating heat sealing. .4 to 0.7) is preferable from the viewpoint of the secondary workability. In particular, it is preferable that the m value satisfies the above range even at, for example, 80 ° C.
[0087]
Further, the F2 value in the longitudinal direction at 25 ° C. of the biaxially oriented polypropylene film of the present invention is preferably 40 MPa or more. Here, the F2 value in the longitudinal direction refers to a sample cut out at a size of 15 cm in the longitudinal direction and 1 cm in the width direction, when the original length is 50 mm and the elongation is 2% when stretched at a pulling speed of 300 mm / min. Such stress. If the F2 value in the longitudinal direction at 25 ° C. is less than the above range, the rigidity in the width direction is higher than that in the longitudinal direction, and the rigidity may be unbalanced. For this reason, the stiffness of the film may be insufficient. At the time of film processing such as printing, laminating, coating, vapor deposition, bag making, releasing, etc., printing pitch deviation, film elongation, wrinkling, film cracking (crack). And the tensile strength of the film may be insufficient. The F2 value in the longitudinal direction at 25 ° C. is determined by cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, longitudinal stretching conditions (temperature, magnification, etc.), crystallinity of polypropylene to be used (mesopentad fraction (mmmm ), Isotactic index (II), etc.), and the mixing amount of a stretching aid. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The F2 value in the longitudinal direction at 25 ° C. is more preferably 45 MPa or more.
[0088]
The F5 value in the longitudinal direction at 25 ° C. of the biaxially oriented polypropylene film of the present invention is preferably 50 MPa or more. Here, the F5 value in the longitudinal direction means that a sample cut out in a size of 15 cm in the longitudinal direction and 1 cm in the width direction is stretched at an original length of 50 mm and a tensile speed of 300 mm / min. Such stress. If the F5 value in the longitudinal direction at 25 ° C. is less than the above range, the rigidity in the width direction is higher than that in the longitudinal direction, and the rigidity may be unbalanced. For this reason, the stiffness of the film may be insufficient. At the time of film processing such as printing, laminating, coating, vapor deposition, bag making, releasing, etc., printing pitch deviation, film elongation, wrinkling, film cracking (crack). And the tensile strength of the film may be insufficient. The F5 value in the longitudinal direction at 25 ° C. is determined by cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, longitudinal stretching conditions (temperature, magnification, etc.), and the crystallinity (mesopentad fraction (mmmm ), Isotactic index (II), etc.), and the mixing amount of a stretching aid. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The F5 value in the longitudinal direction at 25 ° C. is more preferably 55 MPa or more.
[0089]
The biaxially stretched polypropylene film of the present invention preferably has a breaking strength in the longitudinal direction at 25 ° C. of 180 MPa or more. When the breaking strength in the longitudinal direction at 25 ° C. is less than the above range, the tensile strength becomes insufficient during film processing, or the rigidity in the width direction becomes higher than that in the longitudinal direction, and the rigidity becomes unbalanced. There is. For this reason, the stiffness of the film may be insufficient. At the time of film processing such as printing, laminating, coating, vapor deposition, bag making, releasing, etc., printing pitch deviation, film elongation, wrinkling, film cracking (crack). And the tensile strength of the film may be insufficient. The breaking strength in the longitudinal direction at 25 ° C. includes the cooling drum temperature for cooling and solidifying from a molten state to obtain an unstretched sheet, the longitudinal stretching conditions (temperature, magnification, etc.), and the crystallinity of the polypropylene used (mesopentad fraction (mmmm ), Isotactic index (II), etc.), and the mixing amount of a stretching aid. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The breaking strength in the longitudinal direction at 25 ° C. is more preferably 200 MPa or more, further preferably 220 MPa or more, and most preferably 240 MPa or more.
[0090]
The heat shrinkage in the longitudinal direction at 120 ° C. of the biaxially oriented polypropylene film of the present invention is preferably 5% or less. If the heat shrinkage in the longitudinal direction at 120 ° C. exceeds the above range, the film shrinks when a temperature is applied during film processing such as printing, laminating, coating, vapor deposition, bag making, and releasing, and the film cracks. In some cases, process defects such as (cracks), pitch shifts, and wrinkles may be induced. The heat shrinkage in the longitudinal direction at 120 ° C. is determined by cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, longitudinal and transverse stretching conditions (stretching temperature, magnification, relaxation of the film after stretching, etc.), It can be controlled by the crystallinity (corresponding to mmmm, II, etc.) of the polypropylene used, the mixing amount of the stretching aid, and the like. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The heat shrinkage in the longitudinal direction at 120 ° C. is more preferably 4% or less.
[0091]
The sum of the longitudinal heat shrinkage and the transverse heat shrinkage at 120 ° C. of the biaxially oriented polypropylene film of the present invention is preferably 8% or less. When the sum of the heat shrinkage in the longitudinal direction and the heat shrinkage in the width direction at 120 ° C exceeds the above range, printing, laminating, coating, vapor deposition, bag making, releasing a temperature during film processing such as releasing. The shrinkage of the film is increased, which may induce process defects such as film cracks, pitch shifts, and wrinkles. The sum of the heat shrinkage in the longitudinal direction and the width direction at 120 ° C. is determined by the cooling drum temperature and the longitudinal and transverse stretching conditions (stretching temperature, magnification, film after stretching) when cooling and solidifying from a molten state to obtain an unstretched sheet. , Etc.), the crystallinity of the polypropylene used (corresponding to mmmm, II, etc.), the mixing amount of the stretching aid, and the like. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The sum of the heat shrinkage in the longitudinal direction and the heat shrinkage in the width direction at 120 ° C. is more preferably 6% or less.
[0092]
The water vapor transmission rate of the biaxially oriented polypropylene film of the present invention is 1.5 g / m²/D/0.1 mm or less. When the water vapor transmission rate exceeds the above range, for example, the moisture resistance when the biaxially oriented polypropylene film of the present invention is used for a package for shielding the contents from the outside air may be poor. The water vapor transmission rate is determined by cooling drum temperature when cooling and solidifying from a molten state to obtain an unstretched sheet, longitudinal and transverse stretching conditions (stretching temperature, magnification, etc.), crystallinity of the used polypropylene (corresponding to mmmm, II, etc.), It can be controlled by the mixing amount of the stretching aid and the like. Therefore, optimal film forming conditions and raw materials may be appropriately selected within a range that does not impair the characteristics of the present invention. The water vapor transmission rate is more preferably 1.2 g / m²/D/0.1 mm or less.
[0093]
A known method can be used for producing the biaxially oriented polypropylene film of the present invention. For example, a polypropylene containing a polypropylene having a trouton ratio of 30 or more, or a polypropylene having a trouton ratio of 16 or more, and at least one kind of a petroleum resin substantially free of a polar group and / or a terpene resin substantially free of a polar group In the case of forming a laminate obtained by laminating the second, third,... Layers on at least one surface of the film, desired resins are prepared as necessary. These resins are supplied to separate extruders and melted at a temperature of 200 to 290 ° C., and after passing through a filter, (in the case of a laminate, they are joined together in a short tube or a die, and each intended product is mixed. It is extruded from a slit-shaped die (with a lamination thickness), wound around a cooling drum and cooled and solidified into a sheet to form an unstretched (lamination) film. It is preferable that the temperature of the cooling drum is 20 to 100 ° C. and that the film is appropriately crystallized from the viewpoint of improving the rigidity in the longitudinal direction. As a method of contacting the cooling drum, any of an electrostatic application method, a contact method using surface tension of water, an air knife method, a press roll method, and an underwater casting method may be used. As a method for obtaining the biaxially oriented polypropylene film of the present invention, an air knife method having good thickness controllability is preferable.
[0094]
Next, the obtained unstretched (laminated) film is biaxially stretched using a known general-purpose longitudinal-lateral sequential biaxial stretching method. First, the unstretched film is preheated by passing through a roll maintained at a predetermined temperature, and then the film is maintained at a predetermined temperature and passed between rolls provided with a peripheral speed difference, stretched in the longitudinal direction, and immediately cooled to room temperature. I do. Here, an important point for producing a biaxially stretched polypropylene film highly strengthened in the longitudinal direction is a stretching ratio in the longitudinal direction (= longitudinal direction). The effective stretching ratio in the longitudinal direction when forming a normal longitudinal-lateral sequential biaxially stretched polypropylene film is in the range of 4.5 to 5.5 times, and if it exceeds 6 times, stable film formation becomes difficult. In contrast, the biaxially stretched polypropylene film of the present invention preferably has an effective stretch ratio of 6 times or more in the longitudinal direction, whereas the film is broken in the transverse stretching. When the effective stretching ratio in the longitudinal direction is less than the above range, the rigidity of the obtained film in the longitudinal direction may be insufficient, and the rigidity of the film at the time of thinning may be insufficient. The effective stretching ratio in the machine direction is more preferably 7 times or more, and further preferably 8 times or more. At this time, performing the longitudinal stretching in at least two stages may be preferable from the viewpoint of strengthening in the longitudinal direction and suppressing surface defects. The longitudinal stretching temperature may be appropriately selected from the viewpoints of stable film forming properties, suppression of thickness unevenness, and strengthening in the longitudinal direction, and is preferably 120 to 150 ° C. In the cooling process after the longitudinal stretching, it is preferable from the viewpoint of the dimensional stability in the longitudinal direction that the film is relaxed in the longitudinal direction so that the thickness unevenness of the film is not deteriorated. Further, a desired resin layer may be appropriately provided on the film after longitudinal stretching by extrusion lamination or coating.
[0095]
Subsequently, the longitudinally stretched film is guided to a tenter type stretching machine, preheated at a predetermined temperature, and stretched in the width direction. Here, the effective stretching ratio in the width direction is preferably 10 times or less. If the effective stretching ratio in the width direction exceeds 10 times, the obtained film may have insufficient rigidity in the longitudinal direction or may have an unstable film formation. The transverse stretching temperature may be appropriately selected from the viewpoint of stable film forming properties, thickness unevenness, and strengthening in the longitudinal direction, and is preferably 150 to 180 ° C.
[0096]
After stretching in the width direction, the sheet is heat-set at 150 to 180 ° C. while giving a relaxation of 1% or more in the width direction, and cooled. Further, if necessary, at least one surface of the film is subjected to a corona discharge treatment in air, nitrogen, or a mixed atmosphere of carbon dioxide and nitrogen. At this time, when a heat seal layer is laminated, it is preferable not to perform corona discharge treatment in order to obtain high heat seal strength. Next, the film is wound up to obtain a biaxially oriented polypropylene film used in the present invention.
[0097]
The biaxially oriented polypropylene film of the present invention has high rigidity in the longitudinal direction as compared with the conventional biaxially oriented polypropylene film, so that it has excellent tensile strength during film processing, and balances rigidity in the longitudinal direction and the width direction. Therefore, even if the film is made thinner, it has sufficient rigidity. Thus, the biaxially oriented polypropylene film of the present invention not only has excellent handling properties of the film, but also has excellent tensile strength against processing tension during film processing such as printing, laminating, coating, vapor deposition, and bag making. Troubles caused by the base film such as pitch shift, film elongation, wrinkling, and film cracking can be eliminated.
[0098]
In addition, even if it is thinner than conventional general-purpose biaxially oriented polypropylene film, it has excellent dimensional stability and moisture resistance, so even if it is thinner than conventional, it does not impair other properties such as dimensional stability, moisture resistance, etc. Characteristics can be retained. In addition, since an existing vertical-horizontal sequential biaxial stretching machine is used, a large-capacity investment is not required, and a film having the above characteristics can be stably manufactured at low cost.
[0099]
Further, the biaxially stretched polypropylene film of the present invention can improve the secondary workability and gas barrier performance of the structure even when the film is processed into a structure after being composited with another film. Further, since the film of the present invention or another film to be combined with the film of the present invention can be appropriately thinned without impairing general characteristics, waste and resources can be reduced.
[0100]
From the above, the biaxially oriented polypropylene film of the present invention can be preferably used for packaging use, industrial use, and the like.
[0101]
Examples of application of the biaxially stretched polypropylene film of the present invention are shown below as examples, but the present invention is not limited to these.
(1) Straight cutting film
By laminating a uniaxially oriented layer (B layer) on at least one surface of the biaxially stretched polypropylene film (A layer) of the present invention, it is possible to impart straight-line hand-cutting properties in the uniaxially oriented direction of the B layer.
[0102]
Here, the straight cutting property means the property of the laminated film that can be easily cut straight by hand. Specifically, the end of the laminated film is held with the thumb and forefinger so that the left and right thumbs and the left and right index fingers are in contact with each other, and a rapid force is applied to twist the laminated film end in the cutting direction. In the case of tearing, it refers to the property that it can be easily torn with a straight hand.
[0103]
The structure of the laminated film is at least a two-layer structure of A layer / B layer, and a C layer (C layer / A layer / B layer or A layer / B layer) for imparting gloss to at least one side of the structure. / C layer) or a D layer (A layer / D layer / B layer) for improving the adhesion between the A layer and the B layer.
[0104]
For the above-mentioned C layer, it is preferable to use an ethylene / propylene random copolymer, and for the D layer, a polypropylene resin having a mmmm of 70 to 90% (homopolypropylene, propylene and α-olefin (excluding propylene)) Or a mixture thereof) as a main component, and polyethylene, polypropylene, ethylene / propylene copolymer using a metallocene catalyst and the like can also be used.
[0105]
Further, the lamination ratio of the layer A and the layer B preferably satisfies the following relationship.
[0106]
0.05 ≦ t_a/ (T_a+ T_b) ≦ 0.5
Where t_a, T_bIs the thickness of layer A and layer B, respectively. If the lamination ratio is less than the above range, the film may break when unwinding and winding the film, and the handling property may be insufficient. If the lamination ratio exceeds the above range, the straightness of the laminated film may be insufficient.
[0107]
Examples of the resin used for the uniaxially oriented layer (B layer) include homopolymers of ethylene or α-olefin, and copolymers of at least two or more monomer components of ethylene or α-olefin. Of these, a polyolefin-based resin obtained by mixing two or more kinds or graft-polymerizing a compound having a polar group such as maleic acid or maleic anhydride is preferable. Specifically, the B layer was formed by homopolymerization of ethylene, propylene random copolymer, ethylene / propylene block copolymer, ethylene / propylene / butene terpolymer, and graft polymerization of maleic acid or maleic anhydride thereto. More preferably, it is composed of a modified polyolefin copolymer or a mixture thereof. Further, a resin other than the polyolefin-based resin may be added and mixed, and an optimum resin may be appropriately selected. In the present invention, it is particularly preferable to use homopolypropylene and / or an ethylene / propylene random copolymer for the layer B resin from the viewpoints of transparency, extrusion lamination properties, hand-cutting properties, and the like. Further, for example, an ethylene-propylene block copolymer may be used as the B-layer resin or the resin to be laminated on the opposite A-layer surface to impart a matte feeling to the laminated film, or to impart heat sealability. As the resin to be laminated on the layer A surface or the layer B surface, an ethylene / propylene / butene terpolymer may be used.
[0108]
It is preferable that the uniaxial orientation direction of the layer B substantially coincides with either the longitudinal direction or the width direction of the film (layer A) of the present invention to be laminated. When processing (laminate, bag making, etc.) into a packaging bag, cutability mainly in the horizontal direction (= width direction) is often required, so the uniaxial orientation direction of layer B is the width direction of layer A. Preferably substantially coincides with
[0109]
The method of laminating the B layer is not particularly limited. However, when the uniaxial orientation direction of the B layer is made to coincide with the longitudinal direction of the A layer, the B layer is prepared in advance as a uniaxially stretched film, and laminated on at least one surface of the A layer. Can be exemplified. When the uniaxial orientation direction of the B layer is made to coincide with the width direction of the A layer, in the biaxial stretching step of the A layer, the B layer resin is extrusion-laminated on at least one surface of the longitudinally stretched film (A layer). Then, a method in which the layer A is biaxially oriented and the layer B is uniaxially (widthwise) oriented by laterally stretching the laminate can be exemplified. Among these, the latter method of laminating the B layer in the biaxial stretching step of the A layer, which is the film of the present invention, can reduce the processing step by one step, and furthermore, the longitudinal stretching can be performed as compared with the conventional film. Since the width fluctuation of the longitudinally stretched film due to the change in magnification may be reduced in some cases, it is particularly preferable from the viewpoint of productivity. In the latter method, the melt flow rate (MFR) of the layer B resin is preferably from 5 to 30 g / 10 min, more preferably from 7 to 20 g / 10 min, from the viewpoint of extrusion laminating properties.
[0110]
The laminated film can be appropriately laminated with another film, and can be used for packaging soups, chemicals, confectionery, and the like, and as a base film of an adhesive tape, for example, by utilizing the straight cutting property.
[0111]
The biaxially-stretched polypropylene film of the present invention used for the layer A of the laminated film is more isotropically biaxially oriented than the conventional general-purpose biaxially-stretched polypropylene film, and has increased rigidity in the longitudinal direction. Therefore, it is possible to improve the tensile strength and impact resistance of the laminated film while maintaining the straight hand-cutting property equivalent to that of the conventional straight hand-cutting film. At this time, since the laminated film has excellent dimensional stability and moisture resistance, the film of the present invention used for the A layer can be made thinner than the conventional film (when a conventional general-purpose biaxially oriented polypropylene film is used for the A layer). In addition, the processing characteristics of the laminated film itself can be maintained. Further, when a conventional general-purpose biaxially stretched polypropylene film is used for the A layer, it has been a problem that the film breaks when unwinding and winding the film because of its hand-cutting property. In the above-mentioned laminated film, by appropriately controlling the thickness ratio of the layer A and the layer B, the above-mentioned problem can be solved while maintaining the straight cutting property, and the handling property of the film itself can be improved. Furthermore, when the laminated film is used as a base film of an adhesive tape, since the rigidity in the longitudinal direction can be increased while maintaining the straight cutting property, the film is stretched when the tape is used. Can be eliminated.
(2) Matte matte film
By laminating a matting layer (E layer) on at least one surface of the biaxially oriented polypropylene film (layer A) of the present invention, the design of the film (matting effect) can be imparted.
[0112]
The matte layer resin has at least T.sub.T on a calorific curve measured by a differential scanning calorimeter (DSC)._m1: 50-130 ° C and T_m2: Melting peak at 140 ° C to 170 ° C (P₁, P₂), That is, a melting point. Specifically, at least T_m1A resin having a melting peak at an island phase, and having an incompatible T with the island phase resin._m2It is more preferable to have a sea-island structure containing a sea phase resin having a melting peak as a main component.
[0113]
In the laminated film, the resin having the sea-island structure was laminated on at least one surface of the layer A as a mat layer (E layer), and fine and uniform irregularities were provided on the surface, so that the film itself was calm and calm. A surface effect (matte effect) can be provided.
[0114]
P used for E layer₁It is preferable to use polyethylene as the island phase resin having, such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, polyethylene using a metallocene catalyst, and the like. And at least one resin selected from the group consisting of: The polyethylene may be copolymerized with at least one other copolymer component (for example, propylene, butene-1, hexene-1, vinyl acetate, etc.). P₁Is preferably 5 to 50% by weight from the viewpoint of the delustering effect.
[0115]
P used for E layer₂It is preferable to use homopolypropylene, a copolymer of propylene and an α-olefin (excluding propylene), and a mixture thereof as the sea-phase resin having The α-olefin of the above-mentioned copolymer component is not particularly limited, and examples thereof include at least one or more of ethylene, butene-1, isobutene, hexene-1, 4-methylpentene-1, and styrene. P₂The addition amount of the sea-phase resin having the following is preferable from the viewpoint of exhibiting the matting effect.
[0116]
As the resin used for the E layer, the above P₁, P₂It is preferable to use an ethylene / propylene block copolymer having the following formula: The block polymer portion of the resin preferably has an ethylene content of 50 to 100% by weight from the viewpoint of a matting effect, and the polymer portion other than the block polymer portion has a propylene content of 80% by weight or more. It is preferable from the viewpoint of the heat resistance of the B layer.
[0117]
Further, it is preferable to add an organic peroxide to the resin used for the E layer from the viewpoint of improving the fluidity during melting. The organic peroxide is not particularly limited, for example, lauroyl peroxide, benzoyl peroxide, cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane-3 And the like.
[0118]
The amount of the organic peroxide to be added is preferably 0.001 to 1 part by weight based on 100 parts by weight of the E layer resin. If the addition amount is less than the above range, the effect of adding the organic peroxide is not seen, and if it exceeds the above range, the addition effect is seen, but the fluidity of the E layer resin becomes too high (MFR becomes high). ), The layer E resin cannot be uniformly laminated, and unevenness may occur in the matting effect.
[0119]
Where P₁, P₂Heat of fusion (each H₁, H₂Are preferably 10 mJ / mg or more. P₁, P₂In the case where the calorific curves are overlapped, the respective heats of fusion may be calculated by curve fitting as appropriate. If the heat of fusion is less than the above range, the matte effect of the laminated film may be insufficient. In addition, from the viewpoint of the appearance of the matting effect, H₁, H₂Preferably satisfies the following expression.
[0120]
0.05 ≦ H₁/ (H₁+ H₂) ≦ 0.25
H₁, H₂If the above range is not satisfied, the matte properties of the laminated film may be insufficient.
[0121]
The method of laminating the layer E is not particularly limited, but is, for example, a method of laminating on at least one surface of the layer A by coextrusion and biaxially stretching the film, and a film after longitudinal stretching in the biaxial stretching step of the layer A (layer A). It is preferable to extrude and laminate an E-layer resin on at least one side of the laminate, and horizontally stretch the laminate.
[0122]
The layer thickness of the E layer is preferably 1 μm or more. The matte feeling of the laminated film can be controlled by the layer thickness of the E layer, but if the layer thickness is less than the above range, the matte feeling may be insufficient. The layer thickness of the E layer is more preferably 2 μm or more.
[0123]
The center line average surface roughness (Ra) of the laminated film is preferably 0.3 μm or more. If Ra is less than the above range, the matte properties of the laminated film may be insufficient. Ra is preferably 0.4 μm or more, more preferably 0.5 μm or more, and most preferably 0.5 μm or more.
[0124]
The laminated film may be appropriately laminated with another film, and by using the matting effect, for example, for packaging of confectionery, snacks, soap, or the like, or for laminating printed materials such as books or photographs, and the like. Used for erase processing. Further, when a metal layer is laminated on the laminated film or a metal vapor-deposited layer is provided, a calm appearance without glossiness peculiar to metal can be provided. Further, since the layer B of the laminated film has excellent release properties, it can be used as a release film for molding an unsaturated polyester resin, a melamine resin, or the like.
[0125]
Furthermore, the biaxially oriented polypropylene film of the present invention used for the layer A of the laminated film has a higher rigidity in the longitudinal direction than the conventional general-purpose biaxially oriented polypropylene film, and the rigidity is balanced. Shows excellent tensile strength against processing tension during secondary processing such as printing, laminating, coating, vapor deposition, bag making, and mold release. Printing pitch deviation, loss of matte feeling due to film elongation, wrinkling, film cracking (crack) And the like can be suppressed. Further, since the laminated film is also excellent in dimensional stability and moisture resistance, even if the film of the present invention used for the A layer is thinner than the conventional one (when a conventional general-purpose biaxially oriented polypropylene film is used for the A layer), The processing characteristics of the laminated film itself can be maintained.
(3) Film for condenser
By further controlling the properties of the polypropylene used in the biaxially oriented polypropylene film of the present invention, excellent capacitor properties can be imparted.
[0126]
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, the mesopentad fraction (mmmm) of the film is preferably higher from the viewpoint of improving the withstand voltage characteristics, and is preferably 94% or more. When mmmm is less than the above range, the dielectric breakdown strength of the film may be insufficient. Although there is no upper limit for mmmm as long as the effects of the present invention are exhibited, it is preferably, for example, 99.8% or less from the viewpoint of film formation stability. mmmm is more preferably 94.5% or more, still more preferably 96% or more, even more preferably 98% or more, and most preferably 99% or more.
[0127]
In order to control the mmmm of the film within the above range, it is effective to control the stereoregularity of the polypropylene used to a high degree. The method for producing such a raw material is achieved by controlling the catalyst system (solid catalyst, externally added electron donating compound, etc.) and the purity thereof during the polymerization of polypropylene. In addition, thermal degradation of polypropylene during melt extrusion also causes a reduction in mmmm. Therefore, it is preferable to appropriately consider extruder shapes such as avoiding long-term residence of molten polypropylene and control extrusion conditions.
[0128]
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, the film preferably has an isotactic index of 95 to 99.8%. If II is less than the above range, the dielectric breakdown strength of the film may be insufficient, and if it exceeds the above range, the film formation stability may be deteriorated. II is more preferably 96 to 99.6%, even more preferably 97 to 99.4%. In order to control the II of the film to the above range, a method of selecting a low-molecular-weight component or a low stereoregularity easily soluble in boiling n-heptane of the polypropylene to be used, a method of selecting a moderately low ratio of so-called atactic components, and the like. Can be adopted.
[0129]
When the biaxially stretched polypropylene film of the present invention is used for a film capacitor, it is preferable that foreign matter or the like which may be an insulating defect is not included as much as possible. Specifically, the ash content of the film is preferably 50 ppm or less. If the ash content exceeds the above range, foreign matter may cause insulation defects, and the dielectric breakdown strength may be insufficient. In order to control the ash content of the film within the above range, it is necessary to take measures to prevent dust during the production of the film, as well as use it in the polypropylene polymerization process, and use polypropylene with little catalyst residue remaining in the polypropylene after polymerization. In addition, it is preferable to minimize contamination during melt extrusion (for example, to increase the bleed time for one hour or more, or to reduce the collection ratio of waste film generated when manufacturing another film). The ash content is more preferably at most 40 ppm, even more preferably at most 30 ppm, most preferably at most 20 ppm.
[0130]
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, the type and amount of the antioxidant are important from the viewpoint of long-term heat resistance. The antioxidant has a phenolic group having steric hindrance in the molecular skeleton, and at least one of the antioxidants is a high molecular weight type having a molecular weight of 500 or more. Preferred for prevention.
[0131]
Specific examples of the above include, for example, together with 2,6-di-t-butyl-p-cresol (BHT, molecular weight: 220.4), and 1,3,5-trimethyl-2,4,6-tris (3,3) 5-di-t-butyl-4-hydroxybenzyl) benzene (for example, Irganox 1330 manufactured by Ciba Geigy, molecular weight: 775.2), or tetrakis [methylene-3 (3,5-di-t-butyl-4-hydroxyphenyl) ) Propionate] methane (for example, Irganox 1010 manufactured by Ciba Geigy, molecular weight: 1177.7) and the like are preferably used in combination, but are not limited thereto. Further, the total content of the antioxidant is preferably 0.03 to 1% by weight based on the total amount of the polypropylene. If the total content is less than the above range, the long-term heat resistance may be inferior.If the total content exceeds the above range, bleed out of these antioxidants may cause blocking at high temperatures, which may adversely affect the capacitor element. May have an effect. The total content is more preferably 0.1 to 0.9% by weight, and even more preferably 0.2 to 0.8% by weight.
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, the center line average surface roughness (Ra) of the film is preferably 0.01 to 0.4 μm. If Ra is less than the above range, the film slips poorly and may be inferior in handleability. When the capacitor element is impregnated with insulating oil, the insulating oil does not uniformly penetrate between the film layers, and the capacity during continuous use is reduced. The change may be large. When Ra exceeds the above range, air enters between the layers when the films are laminated, leading to deterioration of the capacitor element, and when a metal vapor-deposited layer is formed as an electrode on the film, pinholes or the like are generated in the metal vapor-deposited layer. In some cases, the dielectric breakdown strength and element life during high-temperature use are reduced, and charges are concentrated when voltage is applied, which may cause insulation defects. Ra is more preferably from 0.03 to 0.3 μm, and still more preferably from 0.04 to 0.25 μm.
[0132]
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, the sum of the heat shrinkage in the longitudinal direction and the width direction at 120 ° C. of the film is preferably 1.5 to 3.5%. If the sum of the heat shrinkage ratios is less than the above range, the tightness due to heat treatment during the production of the capacitor element becomes insufficient, which may adversely affect the shape retention and the capacity change rate. If the sum of the thermal shrinkage ratios exceeds the above range, the mechanical deformation due to heat during the production of the capacitor element is too large, so that stress occurs in the film and / or the contact portion with the external electrode, and the capacity of the capacitor decreases. In some cases, the size may increase or the element may be destroyed. The sum of the heat shrinkage rates is preferably 1.6 to 3.3%, more preferably 1.7 to 3%, and most preferably 1.8 to 2.8%.
[0133]
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, the dielectric breakdown strength (BDV) of the film at 25 ° C. is preferably practically 600 V / μm or more, more preferably 650 V / μm or more. . In addition, the film of the present invention has a high plane orientation and can reduce the variation (standard deviation) of BDV as compared with the conventional one, and is preferably 40 or less, more preferably 30 or less. If none of the above ranges is satisfied, the withstand voltage characteristics of the capacitor may be poor.
[0134]
When the biaxially stretched polypropylene film of the present invention is used as a film capacitor, it may be wound together using a metal layer as an electrode, but a metal deposited layer is provided as an electrode on at least one surface of the film, and the film is wound. It is preferable from the viewpoint of miniaturization of the element. In addition, a known method such as a vacuum evaporation method, a sputtering method, and an ion beam method can be used for attaching the metal evaporation layer. In this case, as a method of installing an insulating groove portion, a laser margin method, an oil margin method, a tape margin method, or the like. A known method such as the above method can be used.
[0135]
When the biaxially oriented polypropylene film of the present invention is used for a film capacitor, for example, by controlling the film characteristics as described above, excellent withstand voltage characteristics can be imparted and the characteristics can be maintained even at high temperatures. Further, the biaxially stretched polypropylene film of the present invention has a high rigidity in the longitudinal direction, and the film partially expands during winding, or wrinkles are formed, and air containing moisture is held in the wrinkles, so that It is possible to prevent a problem that electrical characteristics are deteriorated and a local corona discharge is caused. When a metal deposition layer is provided as an electrode, the biaxially stretched polypropylene film of the present invention has high rigidity in the longitudinal direction, and therefore, it is possible to suppress the occurrence of film cracks (cracks) in the metal deposition layer during the production of a capacitor element. In addition, the dielectric breakdown strength and the element life can be improved. In addition, the rigidity is balanced compared to conventional films, and it has excellent dimensional stability and heat resistance, so even if it is thinner than conventional films, it can maintain processing characteristics and capacitor characteristics. Can be suitably used as a biaxially stretched polypropylene film for ultrathin condensers having a thickness in the first half of 3 μm, 2 μm or 1 μm.
[0136]
[Method of measuring characteristic values]
The terms and measurement methods used in the present invention are described below.
(1) Trouton ratio
Using the inflow pressure loss method, measurement was performed under the following conditions from Cogswell's theory [Polymer Engineering Science, 12, 64 (1972)].
[0137]

Each sample was set and filled in the apparatus at 230 ° C. and held for 3 minutes. After refilling and holding for 3 minutes, measurement was started.
[0138]
According to Cogswell's theory, the pressure drop (ΔP_ent) Can be expressed as the following equation using the shear viscosity and the extensional viscosity.
Where η_E： Extension viscosity, η_s: Shear viscosity, γ_a: Shear rate. N is a power law (σ_s= Kγ_a ⁿ, Σ_s: Shear stress).
In a twin capillary rheometer, the shear viscosity at a certain shear rate, ΔP_entAt the same time, the extensional viscosity η_ECan be obtained from the following equation.
Here, ε is an extensional stress. The obtained elongational viscosity-elongational strain rate curve and shear viscosity-shear rate curve were each approximated as an exponential function, and a strain rate of 60 s was calculated using these functions.^-1Η at_{E (60)}, Η_{s (60)}I asked. From this, the strain rate is 60 s according to the following equation.^-1Ratio at η (η at the same strain rate_EAnd η_sWas calculated.
(2) Young's modulus, F2 value, F5 value, breaking strength
The Young's modulus at 25 ° C., the F2 value, and the F5 value were measured at 65% RH using a film strength / elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. The sample was cut out to a size of 15 cm in the measurement direction and a direction perpendicular to the measurement direction: 1 cm, stretched at an original length of 50 mm and a pulling speed of 300 mm / min, and the Young's modulus was measured according to the method specified in JIS-Z1702. For the F2 value and the F5 value, the stress applied to the sample with respect to the elongation of 2% and 5%, respectively, was measured. The rupture strength was measured under the same conditions as described above, with the stress at break of the sample, and when measuring at a high temperature such as 80 ° C., a high and low temperature constant temperature bath manufactured by Gondoux Science Co., Ltd. was attached.
(3) Mesopentad fraction (mmmm)
Polypropylene is dissolved in o-dichlorobenzene-D6, and the resonance frequency is 67.93 MHz using a JEOL JNM-GX270 apparatus.^ThirteenC-NMR was measured. For the assignment of the obtained spectrum and the calculation of the mesopentad fraction, see T.W. Based on the method performed by Hayashi et al. (Polymer, 29, 138-143 (1988)), the peak derived from the methyl group was assigned with the mmmm peak at 21.855 ppm, and the peak area was determined to determine the peak area. The ratio to the total peak area was expressed as a percentage. Detailed measurement conditions are as follows.
[0139]
Measurement concentration: 15 to 20 wt%
Measurement solvent: o-dichlorobenzene (90 wt%) / benzene-D6 (10 wt%)
Measurement temperature: 120-130 ° C
Resonance frequency: 67.93 MHz
Pulse width: 10μsec (45 ° pulse)
Pulse repetition time: 7.091 seconds
Data point: 32K
Number of integration: 8168
Measurement mode: noise decoupling
(4) Heat shrinkage
Using the measurement direction as the longitudinal direction and the width direction, a sample was sampled from the film to a test length of 260 mm and a width of 10 mm, and the original size (L₀) Is marked at a position of 200 mm. A load of 3 g was applied to the lower end of this sample, heat-treated for 15 minutes in a hot air circulating oven at 120 ° C., taken out at room temperature, and the length (L₁) Is measured. At this time, the heat shrinkage is obtained by the following equation. The above operation was performed in each direction (longitudinal direction, width direction), and the heat shrinkage in the longitudinal direction and width direction, and the sum thereof were obtained.
[0140]
Heat shrinkage (%) = 100 × (L₀-L₁) / L₀
(5) Water vapor transmission rate
The measurement was carried out under the conditions of a temperature of 40 ° C. and a humidity of 90% RH using a water vapor transmission rate measuring apparatus PERMATRAN-W3 / 30 manufactured by MOCON / Modern Controls. For the metal-deposited biaxially stretched polypropylene film, a pressure-sensitive adhesive film made of polypropylene (Scotchmark, 40 μm thickness, manufactured by 3M) was attached to the surface on which the metal was deposited, and the measurement was performed under the above conditions.
(6) Intrinsic viscosity ([η])
The polypropylene dissolved in tetralin at 135 ° C. was measured using an Ostwald viscometer manufactured by Mitsui Toatsu Chemicals, Inc.
(7) Melt flow rate (MFR)
It was measured according to the polypropylene test method (230 ° C., 2.16 kgf) shown in JIS K6758.
(8) Isotactic index (II)
The polypropylene is extracted with n-heptane at a temperature of 60 ° C. or less for 2 hours to remove additives in the polypropylene. Thereafter, vacuum drying is performed at 130 ° C. for 2 hours. From this, a sample of weight W (mg) is taken, placed in a Soxhlet extractor and extracted with boiling n-heptane for 12 hours. Next, the sample was taken out, sufficiently washed with acetone, vacuum-dried at 130 ° C. for 6 hours, and then cooled to room temperature, and the weight W ′ (mg) was measured and determined by the following equation.
[0141]
II = (W ′ / W) × 100 (%)
(9) Glass transition temperature (Tg), melting point (Tm), heat of crystal fusion (H), crystallization temperature (Tmc)
A thermo-analyzer RDC220 manufactured by Seiko Instruments was loaded in an aluminum pan with a sample weight of 5 mg, and the temperature was increased from 30 ° C. to 280 ° C. at a rate of 20 ° C./min. Using the built-in program of the analysis system SSC5200, the starting point of the glass transition is defined as the glass transition temperature (Tg), and when the temperature is further increased, the peak of the endothermic peak accompanying the melting of the crystal is defined as the melting point (Tm). ) Was determined from the area. This area is the area where the heat curve shifts from the baseline to the endothermic side as the temperature rises and then returns to the baseline position.The area from the melting start temperature position to the end temperature position is connected by a straight line, and this area is calculated by computer. Processed and determined. When a plurality of endothermic peaks were observed, the peaks were appropriately separated by computer processing to determine the heat of fusion. After the completion of the temperature rise, the system was kept at 280 ° C. for 5 minutes, and then cooled to 30 ° C. at a rate of 20 ° C./min. At this time, the peak of the exothermic peak accompanying crystallization from the molten state was determined as the crystallization temperature (Tmc).
(10) Bromine value
It measured according to JISK-2543-1979. It is represented by the number of g of bromine added to the unsaturated component in 100 g of the sample oil.
(11) Average particle size (μm)
The volume average diameter measured by the centrifugal sedimentation method (using CAPA500 manufactured by Horiba, Ltd.) was defined as the average particle diameter.
(12) Thickness (μm) of each layer constituting the film
The film was cut using a microtome to form a cross section, and the structure of the film cross section was observed using a field emission scanning electron microscope (FE-SEM) to measure the thickness of each layer.
(13) Straight running ability
Hold the end of the film with your thumb and forefinger so that the left and right thumbs and the left and right index fingers are in contact with each other, and apply a rapid force to twist the film end in the cutting direction and tear it easily with a straight hand. Those that could be torn were marked with ○, those that could not be easily torn by hand, and those that did not tear straight were rated as x.
(14) Center line average surface roughness (Ra)
It was measured using a stylus type surface roughness meter according to JIS B0601. In addition, using a high-precision thin film step measuring device (model: ET-30HK) manufactured by Kosaka Laboratory Co., Ltd., the stylus diameter was 0.5 μmR, the load was 16 mg, and the cutoff was 0.08 mm.
[0142]
At this time, the center line average surface roughness (Ra) is obtained by extracting a portion of the measurement length L from the roughness curve in the direction of the center line, setting the center line of the extracted portion as the X axis and the vertical direction as the Y axis. When the roughness curve is represented by y = f (x), the value obtained by the following equation is represented by μm.
(15) Surface wetting tension
The measurement was carried out based on a measurement method prescribed in JIS K6768 using a mixed solution of formamide and ethylene glycol monoethyl ether.
(16) Effective stretch ratio
After extruding from a slit-shaped die, winding it around a metal drum and cooling and solidifying it on a sheet, after imprinting 1 cm square cells so that each side is parallel to the longitudinal direction and width direction of the film The film was stretched and wound, and the length (cm) of the square of the obtained film was measured, and this was defined as the effective stretching ratio in the longitudinal direction and the lateral direction.
(17) Ash
Initial weight W according to JIS C2330₀The biaxially stretched polypropylene film is put into a platinum crucible, first sufficiently burned with a gas burner, and then treated in an electric furnace at 750 to 800 ° C. for about 1 hour to completely incinerate the obtained ash. Weight W₁Was measured and calculated from the following equation.
[0143]
Ash content = (W₁/ W₀) × 1,000,000 (ppm)
(18) Film breakdown strength (BDV)
It was measured according to JIS C2110. A 100 μm-thick aluminum foil electrode of 10 cm square is used for the cathode, and a brass-type 8 mmφ electrode is used for the cathode. A film is sandwiched between the electrodes, and the voltage is increased at a rate of 100 V / sec using a DC high-voltage stabilizing power supply manufactured by Kasuga Electric Co., Ltd. The voltage was applied while the current was flowing at least 10 mA, which was regarded as a breakdown. The value obtained by dividing the voltage at that time by the film thickness at the measurement point was defined as the dielectric breakdown strength, and the average value was measured at 30 points. The variation was determined by calculating a standard deviation from the data of the 30 points.
(19) Secondary workability
An unstretched polypropylene film having a thickness of 20 μm was dry-laminated on one side of a biaxially stretched polypropylene film of the present invention having a length of 1000 m using a polyurethane adhesive to obtain a film for food packaging. The film was inserted into a cylindrical shape using a vertical pillow wrapping machine (FUJI FW-77) manufactured by Fujiki Kai Co., Ltd. so that the unstretched polypropylene film layer was on the inside, and the bag was formed.
[0144]
At that time, if the film does not have wrinkles or elongation, and the shape of the bag-making product is good, it is marked as ○, and the film has low Young's modulus in the longitudinal direction or low waist, stretches, slips poorly, heat shrinks Those having a bad shape due to wrinkles or the like due to a high rate were evaluated as x.
[0145]
【Example】
The present invention will be described based on examples. In order to obtain a film having a desired thickness, the rotation speed of the extruder and the peripheral speed of the cooling drum were adjusted to predetermined values unless otherwise specified.
[0146]
Example 1
Known polypropylene having a trouton ratio of 12 (melt flow rate (MFR): 2.3 g / 10 min, mesopentad fraction (mmmm): 92%, isotactic index (II): 96%), and a trouton ratio of 50 A polar group as a stretching aid was added to 90% by weight of polypropylene added and mixed at a ratio of 5% by weight of polypropylene having a long chain branch (MFR: 3 g / 10 minutes, mmmm: 97%, II: 96.5%). 100 parts by weight of a resin composition containing 10% by weight of polydicyclopentadiene having a Tg of 80 ° C., a bromine value of 3 cg / g and a hydrogenation rate of 99%, which is substantially free of petroleum resin, and having an average particle size of 2 μm as crosslinked organic particles 0.15 parts by weight of crosslinked particles of a polymethacrylic acid polymer (crosslinked PMMA) as glycerin fatty acid ester as an antistatic agent Alkyl diethanolamine fatty acid ester was mixed at a ratio of 1: 1 and 0.8 parts by weight was added. The mixture was supplied to a twin screw extruder, extruded at 270 ° C. in a gut shape, cooled through a water bath at 20 ° C., and then cooled with a chip cutter. After cutting to a length of 3 mm at 100 ° C., the chips dried at 100 ° C. for 2 hours are fed to a single screw extruder, melted at 280 ° C., extruded from a slit die after passing through a filter, and wound around a metal drum at 25 ° C. to form a sheet. Molded into a shape.
[0147]
The sheet is preheated by passing through a roll maintained at 135 ° C., passed between rolls having a peripheral speed difference maintained at 140 ° C., stretched 9 times in the longitudinal direction, and immediately cooled to room temperature. Subsequently, the stretched film is introduced into a tenter, preheated at 165 ° C., stretched 7 times in the width direction at 160 ° C., and then heat-set at 160 ° C. while giving 8% relaxation in the width direction, and then cooled. Then, a 15 μm-thick biaxially stretched polypropylene film was obtained.
[0148]
Tables 1 and 2 show the raw material composition of the obtained film and the evaluation results of the film characteristics. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0149]
Example 2
In Example 1, a biaxially stretched polypropylene film having a thickness of 15 μm was produced under the same conditions except that the stretching ratio in the longitudinal direction was increased to 11 times.
[0150]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0151]
Example 3
In Example 1, 3% by weight of β-pinene having a Tg of 75 ° C., a bromine number of 4 cg / g and a hydrogenation rate of 99% was mixed as a stretching aid in a terpene resin substantially free of a polar group in the longitudinal direction. Example 3 was a 15-μm-thick biaxially stretched polypropylene film produced under the same conditions except that the film was stretched 8 times in the width direction and 8 times in the width direction.
[0152]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0153]
Example 4
In Example 3, a 15 μm-thick biaxially stretched polypropylene film was produced in the same manner as in Example 4 except that the amount of the terpene resin as a stretching aid was changed to 8% by weight.
[0154]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0155]
Example 5
A 15-μm-thick biaxially-stretched polypropylene film produced under the same conditions as in Example 1 except that the addition amount of the polypropylene having a long chain branch was 10% by weight and the addition amount of the polydicyclopentadiene was 5% by weight. Example 5 was used.
[0156]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0157]
Example 6
85% by weight of a polypropylene having a long chain branch having a troutone ratio of 50 (MFR: 3 g / 10 min, mmmm: 97%, II: 96.5%), a terpene substantially free of a polar group as a stretching aid A resin, 15% by weight of a mixture of β-pinene having a Tg of 75 ° C., a bromine number of 4 cg / g and a hydrogenation rate of 99% and a hydrogenated β-dipentene having a Tg of 75 ° C., a bromine number of 3 cg / g and a hydrogenation rate of 99% was added. To 100 parts by weight of the mixed resin composition, 0.15 parts by weight of crosslinked polystyrene-based polymer particles (crosslinked PS) having an average particle size of 1 μm as crosslinked organic particles was added, and glycerin fatty acid ester and alkyldiethanolamine fatty acid ester were used as antistatic agents. Was mixed at a ratio of 1: 1 and 0.8 parts by weight was added. The mixture was supplied to a twin-screw extruder, extruded in a gut shape at 260 ° C., cooled through a water bath at 20 ° C. After cutting to a length of 3 mm with a filter, the chips dried at 100 ° C. for 2 hours are fed to a single screw extruder, melted at 270 ° C., extruded from a slit die after passing through a filter, and wound around a metal drum at 30 ° C. It was formed into a sheet.
[0158]
The sheet is preheated by passing through a roll maintained at 132 ° C., passed between rolls having a peripheral speed difference maintained at 137 ° C., stretched eight times in the longitudinal direction, and immediately cooled to room temperature. Subsequently, the stretched film is introduced into a tenter, preheated at 162 ° C., stretched eight times in the width direction at 160 ° C., heat-set at 160 ° C. while giving 8% relaxation in the width direction, and then cooled. Then, a 15 μm-thick biaxially stretched polypropylene film was obtained.
[0159]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0160]
Example 7
In Example 6, a polypropylene having a long chain branch having a trouton ratio of 50 (MFR: 3 g) was added to a known polypropylene having a trouton ratio of 12 (MFR: 2.3 g / 10 min, mmmm: 92%, II: 96%). / 10 minutes, mmmm: 97%, II: 96.5%) at a ratio of 5% by weight and mixed with 80% by weight of polypropylene to be compatible with polypropylene. 20% by weight of a polydicyclopentadiene having a Tg of 80 ° C., a bromine number of 3 cg / g and a hydrogenation rate of 99%, which is a petroleum resin not containing, and stretched 11 times in the longitudinal direction and 6 times in the width direction under the same conditions. The biaxially stretched polypropylene film having a thickness of 15 μm prepared in Example 2 was used as Example 7.
[0161]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0162]
Example 8
In Example 3, except that polypropylene having a long chain branch having a trouton ratio of 40 (MFR: 2.0 g / 10 min, mmmm: 95%, II: 96%) was added at a ratio of 15% by weight. In Example 8, a biaxially stretched polypropylene film having a thickness of 15 μm manufactured under the same conditions was used as Example 8.
[0163]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0164]
Example 9
In Example 8, a biaxially stretched polypropylene film having a thickness of 15 μm was produced under the same conditions except that the mixing ratio of the polypropylene having a long chain branch was changed to 10% by weight.
[0165]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0166]
Example 10
In Example 3, a polypropylene obtained by adding and mixing a polypropylene having a long chain branch having a trouton ratio of 60 (MFR: 2.1 g / 10 min, mmmm: 94%, II: 95.5%) at a ratio of 5% by weight was used. A biaxially stretched polypropylene film having a thickness of 15 μm and manufactured under the same conditions as in Example 10 was used as Example 10.
[0167]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0168]
Example 11
In Example 1, 15-μm-thick biaxial stretching prepared under the same conditions except that polypropylene having a long-chain branch was added and mixed at a ratio of 30% by weight and stretched 10 times in the longitudinal direction and 7 times in the width direction. Example 11 was a polypropylene film.
[0169]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0170]
Example 12
In Example 1, a known polypropylene having a trouton ratio of 10 (MFR: 3.1 g / 10 min, mmmm: 98%, II: 99%) was mixed with a polypropylene having a long-chain branch at a ratio of 5% by weight. Example 12 was a biaxially stretched polypropylene film having a thickness of 15 μm and produced under the same conditions except that the obtained polypropylene was stretched 10 times in the longitudinal direction and 8 times in the width direction.
[0171]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0172]
Example 13
In Example 5, a polypropylene having a long chain branch was added at a ratio of 10% by weight to a known polypropylene having a trouton ratio of 11 (MFR: 2.5 g / 10 min, mmmm: 95.5%, II: 96%). Example 13 was a biaxially stretched polypropylene film having a thickness of 15 μm and produced under the same conditions except that the mixed polypropylene was stretched 9 times in the longitudinal direction and 8 times in the width direction.
[0173]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0174]
Example 14
In Example 4, the stretching in the longitudinal direction was divided into two stages and preheated at 135 ° C., and then stretched 1.5 times at 137 ° C. in the first stage and 5.3 times at 142 ° C. in the second stage. A biaxially stretched polypropylene film having a thickness of 15 μm and manufactured under the same conditions as in Example 14 was used as Example 14.
[0175]
The results are shown in Tables 1 and 2. The obtained film had a high Young's modulus in the longitudinal direction, was excellent in tensile strength, and was excellent in moistureproofness, dimensional stability, and secondary workability.
[0176]
[Table 1]

[0177]
[Table 2]

[0178]
Comparative Example 1
In Example 1, a known polypropylene (MFR: 2.3 g / 10 min, mmmm: 92%, II: 96%) having a trouton ratio of 12 alone was stretched 5 times in the longitudinal direction and 10 times in the width direction. Except for this, Comparative Example 1 was a biaxially stretched polypropylene film having a thickness of 15 μm and manufactured under the same conditions.
[0179]
The results are shown in Tables 3 and 4. The obtained film had a low Young's modulus in the longitudinal direction, insufficient tensile strength, and was inferior in moisture-proof property and secondary workability.
[0180]
Comparative Example 2
In Comparative Example 1, a 15-μm-thick biaxially oriented polypropylene film produced under the same conditions except that the longitudinal stretching magnification was increased to 7 times was used as Comparative Example 2.
[0181]
The results are shown in Tables 3 and 4. Since a large number of tears occurred during the transverse stretching, a satisfactory film could not be obtained.
[0182]
Comparative Example 3
Comparative Example 1 was prepared under the same conditions except that a known polypropylene having a trouton ratio of 10 (MFR: 3 g / 10 min, mmmm: 97.5%, II: 99%) alone was used. An axially stretched polypropylene film was used as Comparative Example 3.
[0183]
The results are shown in Tables 3 and 4. The edge of the obtained film was curled up when it was wound around a cooling drum from the molten state, so that the sheet was often cut by longitudinal stretching. In addition, tears sporadically occurred during transverse stretching, and the film was poor in film forming properties as a whole and could not be industrially produced.
[0184]
Comparative Example 4
Comparative Example 1 was manufactured under the same conditions except that a known polypropylene having a trouton ratio of 8 (MFR: 6 g / 10 min, mmmm: 99.8%, II: 99.5%) alone was used. Was used as Comparative Example 4.
[0185]
The results are shown in Tables 3 and 4. Since a large number of tears occurred during the transverse stretching, a satisfactory film could not be obtained.
[0186]
Comparative Example 5
Comparative Example 5 was a 15-μm-thick biaxially-stretched polypropylene film produced under the same conditions as in Example 6 except that a simple polypropylene having a long chain branch was used.
[0187]
The results are shown in Tables 3 and 4. The obtained film had a low Young's modulus in the longitudinal direction, an insufficient tensile strength, and was inferior in secondary workability.
[0188]
Comparative Example 6
In Example 5, an unhydrogenated gum rosin having a bromine value of 15 cg / g at a Tg of 39 ° C. containing a carboxyl group as a polar group having poor compatibility with polypropylene instead of a petroleum resin substantially free of a polar group was used. Comparative Example 6 was a 15 μm thick biaxially stretched polypropylene film produced under the same conditions except that the film was stretched 5 times in the longitudinal direction and 11 times in the width direction.
[0189]
The results are shown in Tables 3 and 4. The resulting film contains a poorly compatible gum rosin with polypropylene, and the Tg of the gum rosin is low, the bromine value is high, and the polar group has a low Young's modulus in the longitudinal and width directions. And the rigidity was insufficient. Further, the Young's modulus in the longitudinal direction was low, the tensile strength was insufficient, and the secondary workability was poor.
[0190]
Comparative Example 7
In Comparative Example 1, a biaxially stretched polypropylene film having a thickness of 15 μm, which was stretched 8 times in the longitudinal direction, wound up as it was after cooling, was taken as Comparative Example 7.
[0191]
The results are shown in Tables 3 and 4. The obtained film was easily torn in the longitudinal direction, and was extremely poor in the handling property of the film, so that it was poor in the secondary workability.
[0192]
Comparative Example 8
In Comparative Example 1, 3% by weight of β-pinene having a Tg of 75 ° C., a bromine number of 4 cg / g and a hydrogenation rate of 99%, which is a terpene resin substantially free of a polar group, as a stretching aid in 97% by weight of polypropylene. Comparative Example 8 was a 15-μm-thick biaxially stretched polypropylene film produced under the same conditions except that the resin composition was used to add 5% in the longitudinal direction and 9-fold in the width direction.
[0193]
The results are shown in Tables 3 and 4. The resulting film had a low Young's modulus in the longitudinal direction, insufficient tensile strength, and poor secondary workability.
[0194]
Comparative Example 9
In Comparative Example 8, a biaxially oriented polypropylene film having a thickness of 15 μm was produced under the same conditions except that the film was stretched 7 times in the longitudinal direction and 8 times in the width direction.
[0195]
The results are shown in Tables 3 and 4. During the transverse stretching, tears sporadically occurred, a film having a sufficient length could not be collected, and the film could not be industrially produced.
[0196]
Comparative Example 10
In Comparative Example 8, a biaxially oriented polypropylene film having a thickness of 15 μm was produced under the same conditions except that the stretching ratio in the longitudinal direction was further increased to 8 times.
[0197]
The results are shown in Tables 3 and 4. Since a large number of tears occurred during the transverse stretching, a satisfactory film could not be obtained.
[0198]
Comparative Example 11
Comparative Example 8 was a comparative example 11 of a biaxially stretched polypropylene film having a thickness of 15 μm produced under the same conditions except that the amount of β-pinene was changed to 10 weight.
[0199]
The results are shown in Tables 3 and 4. The obtained film had a low Young's modulus in the longitudinal direction at 80 ° C., had insufficient tensile strength, and was inferior in dimensional stability and secondary workability.
[0200]
Comparative Example 12
In Comparative Example 11, a 15-μm-thick biaxially-stretched polypropylene film was produced under the same conditions except that the film was stretched 8 times in the longitudinal direction and 7 times in the width direction.
[0201]
The results are shown in Tables 3 and 4. During the transverse stretching, tears sporadically occurred, a film having a sufficient length could not be collected, and the film could not be industrially produced.
[0202]
Comparative Example 13
In Comparative Example 11, a 15-μm-thick biaxially-stretched polypropylene film produced as Comparative Example 13 was produced under the same conditions except that the stretching ratio in the longitudinal direction was further increased to 9 times.
[0203]
The results are shown in Tables 3 and 4. Since a large number of tears occurred during the transverse stretching, a satisfactory film could not be obtained.
[0204]
Comparative Example 14
In Comparative Example 1, the same conditions were used except that 0.2 parts by weight of sodium 2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate was added as a nucleating agent to 100 parts by weight of polypropylene. The prepared biaxially stretched polypropylene film having a thickness of 15 μm was used as Comparative Example 14.
[0205]
The results are shown in Tables 3 and 4. The resulting film had a low Young's modulus in the longitudinal direction, insufficient tensile strength, and poor secondary workability. In addition, as compared with Comparative Example 1, defects due to fish eyes increased.
[0206]
[Table 3]

[0207]
[Table 4]

[0208]
From Tables 1 to 4, the biaxially stretched polypropylene film of the present invention has a trouton ratio of 30 or more, or has a trouton ratio of 16 or more, and contains one or more stretching aids. Thus, a film having excellent tensile strength, dimensional stability, and moisture resistance was obtained. In addition, a film having such excellent characteristics could be stably formed using a general-purpose vertical-horizontal sequential biaxial stretching machine without process defects such as tearing.
[0209]
【The invention's effect】
The biaxially oriented polypropylene film of the present invention has high rigidity in the longitudinal direction as compared with the conventional biaxially oriented polypropylene film, so that it has excellent tensile strength during film processing, and balances rigidity in the longitudinal direction and the width direction. Therefore, even if the film is made thinner, it has sufficient rigidity. Thus, the biaxially oriented polypropylene film of the present invention not only has excellent handling properties of the film, but also has excellent tensile strength against processing tension during film processing such as printing, laminating, coating, vapor deposition, and bag making. Troubles caused by the base film such as pitch shift, film elongation, wrinkling, and film cracking can be eliminated.
[0210]
In addition, even if it is thinner than conventional general-purpose biaxially oriented polypropylene film, it has excellent dimensional stability and moisture resistance, so even if it is thinner than conventional, it does not impair other properties such as dimensional stability, moisture resistance, etc. Characteristics can be retained. In addition, since an existing vertical-horizontal sequential biaxial stretching machine is used, a large-capacity investment is not required, and a film having the above characteristics can be stably manufactured at low cost.
[0211]
Further, the biaxially stretched polypropylene film of the present invention can improve the secondary workability and gas barrier performance of the structure even when the film is processed into a structure after being composited with another film. Further, since the film of the present invention or another film to be combined with the film of the present invention can be appropriately thinned without impairing general characteristics, waste and resources can be reduced.
[0212]
From the above, the biaxially oriented polypropylene film of the present invention can be preferably used for packaging use, industrial use, and the like.

Claims (10)

A biaxially stretched polypropylene film comprising a polypropylene having a trouton ratio of 30 or more, and one or more stretching aids mixed therein. A biaxially stretched polypropylene film, wherein one or more stretching aids are mixed with polypropylene having a trouton ratio of 16 or more. A biaxially stretched polypropylene film comprising a polypropylene having a long chain branch, wherein one or more stretching aids are mixed. The biaxially oriented polypropylene film according to any one of claims 1 to 3, wherein the stretching aid is a petroleum resin substantially free of a polar group and / or a terpene resin substantially free of a polar group. Longitudinal Young's modulus _{(Y MD)} is biaxially oriented polypropylene film according to claim 1 is 2.5GPa or more 25 ° C.. The biaxially stretched polypropylene film according to any one of claims 1 to 5, wherein the polypropylene has a mesopentad fraction (mmmm) of 90 to 99.5%. The biaxially stretched polypropylene film according to any one of claims 1 to 6, wherein a heat shrinkage in a longitudinal direction at 120 ° C is 5% or less. Longitudinal Young's modulus _{(Y MD)} and the Young's modulus in the transverse direction _{(Y TD)} in represented by the formula (1) m value _{m = Y MD / (Y MD} + Y TD) (1)
Is from 0.4 to 0.7 at 25 ° C. The biaxially stretched polypropylene film according to any one of claims 1 to 8, having a water vapor transmission rate of 1.5 g / m2 / d / 0.1 mm or less. The biaxially stretched polypropylene film according to any one of claims 1 to 9, wherein the crystallization temperature (Tmc) of the polypropylene is 110 ° C or higher.