JP3551485B2 - Polyolefin composite film - Google Patents
Polyolefin composite film Download PDFInfo
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- JP3551485B2 JP3551485B2 JP21810494A JP21810494A JP3551485B2 JP 3551485 B2 JP3551485 B2 JP 3551485B2 JP 21810494 A JP21810494 A JP 21810494A JP 21810494 A JP21810494 A JP 21810494A JP 3551485 B2 JP3551485 B2 JP 3551485B2
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- polyolefin
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Description
【0001】
【産業上の利用分野】
本発明は透明性、滑り性及び耐ブロッキング性に優れ、透明性が高度に要求される包装用の分野又はその他の分野に好適に使用されるポリオレフイン系複合フイルムに関するものである。
【0002】
【従来の技術】
従来ポリオレフィン系フイルムの滑り性、耐ブロッキング性を改良する方法として、例えばシリカ、炭酸カルシウム、クレ−、チタンホワイト、ゼオライト等の無機の微粒子を添加し、フイルムの表面性質を変化せしめることによってブロッキング性を改良する方法(特公昭52−16134号公報、特開平3−9938号公報)がある。しかしながら無機物質の微粒子は凝集し易く、ポリオレフィン系樹脂との屈折率の差が大きいことよりポリオレフィン系複合フイルムの透明性が損われ、更にポリプロピレン系樹脂と無機物質との親和性が少ないことより無機物質を核にしてボイドが発生して透明性が低下する。
【0003】
従って透明性が要求される延伸フイルムに対して満足できる滑り性及び耐ブロッキング性を与えるに充分な量の微粒子状無機物質を添加することは上記の理由により不可能である。これら微粒子の無機物質を添加したポリオレフィンフイルムの欠点を補うために有機ポリマ−の微粒子を添加したポリプロピレン系複合フイルムとして、ポリプロピレン系樹脂に対して粒径3〜40μの架橋構造を有し、かつ融点を有しない高分子微粉末をポリプロピレン系樹脂に対して0.02〜0.8重量%均一に混合し、溶融押出した後冷却し、これを少なくとも一軸方向に延伸する延伸ポリプロピレン系樹脂フイルム(特開昭57−64522号)があり、更に延伸ポリオレフィンフイルムに対しては、平均粒子径0.5〜10μの球状のトリアジン環を有する縮合型樹脂をポリオレフィンに対して0.01〜0.1重量%の割合で含有し、かつ少なくとも一軸方向に4倍以上延伸された延伸ポリオレフィン系フイルムの発明(特開昭62−39219号)がある。
【0004】
しかしながら本発明者等の検討結果によると、従来の有機ポリマ−微粒子を使用したポリオレフィン系複合フイルムは無機微粒子を使用したポリオレフィン系複合フイルムに比較して透明性や耐スクラッチ性に優れているが、透明性と滑り性並びに耐ブロッキング性のバランスにおいては不充分であり、高度な市場要求を満足するレベルには達していないのである。
【0005】
【発明が解決しようとする課題】
上記したように透明性、滑り性と耐ブロッキング性とが共に優秀なポリオレフィン系複合フイルムに対しては従来の無機微粒子を添加する方法は勿論、従来の有機のポリマ−粒子を使用する方法も共に上記したように不充分であり、特にポリオレフィン系複合フイルムの透明性、滑り性及び耐ブロッキング性のバランスにおいて高度な市場要求を満足するレベルには達していないという問題点があった。即ち、高度な透明性を達成するために、ポリオレフィン系複合フイルムに添加すべき微粒子の量を低減させる場合は滑り性や耐ブロッキング性が悪化してフイルムの製造工程や加工工程における作業性に問題を生じ、逆に滑り性や耐ブロッキング性の特性を満足させる場合は、透明性が低下するため、透明性及び滑り性と耐ブロッキング性との相反する特性が共に優れているというポリオレフィン系複合フイルムは未だ得られていないのである。
上記に鑑み、本発明は透明性と滑り性及び耐ブロッキング性とが共に優れたポリオレフィン系複合フイルムを提供することを目的とするものである。
【0006】
【課題を解決するための手段】
本発明の第1は、ポリオレフィン系重合体より形成された複合フイルムの基層の少なくとも片面に、平均粒径0.4〜7.0μmで、かつ水滴保持時間が10秒以上である有機ポリマ−微粒子の配合が表面層のもであるポリオレフィン系重合体100重量%に対して0.01〜2重量部を含むポリオレフィン系重合体のフイルムが複層、積層されてなることを特徴とするポリオレフィン系複合フイルムに関するものである。
【0007】
その第2は、上記の第1発明において、有機ポリマ−微粒子がアクリル系モノマ−又はメタアクリル系モノマ−〔(メタ)アクリル系モノマ−と略称する〕及び/又はスチレン系モノマ−を含むモノマ−成分からなるポリマ−であることを特徴とするポリオレフイン系複合フイルムであり。
【0008】
更にその第3は、上記第1、第2発明において表面層のフイルムの厚さが0.03〜4μmであることを特徴とするポリオレフィン系複合フイルムに関するものである。
ここに、水滴保持時間とは、
有機ポリマ−微粒子を水平で平滑な台上で2枚の2軸延伸ポリプロピレンフイルムの間に狭持させ、上側フイルムを手で軽く押さえて厚さ2mmの平滑な有機ポリマ−微粒子層を形成させた後、上側フイルムを静かに取り外す。得られた有機ポリマ−微粒子層表面にスポイドで直径2mmの水滴を高さ1cmのところから落し、該水滴が有機ポリマ−微粒子層に吸収され、水滴が消失するまでの時間をいう。
【0009】
本発明のポリオレフィン系複合フイルムを構成するポリオレフィンとしては基層及び表面層共にプロピレン、エチレン、ブテン、4−メチルペンテン−1等の単独重合体もしくはこれらの共重合体の混合物が挙げられる。基層及び表面層を構成するポリオレフィンの種類は同一であっても異なっていても、何れでも差し支えない。
【0010】
本発明に使用される有機ポリマ−微粒子は上記ポリオレフィンの溶融成形温度で非溶融で、かつ同温度に耐える耐熱性を有するものであれば特に制限はなく、付加重合法で得られたものであってもよく、また重縮合や重付加反応法で得られたものでもよい。該有機ポリマ−微粒子を構成するポリマ−は非架橋タイプであっても架橋タイプであってもよいが、耐熱性の点より架橋タイプの方がより好適である。
【0011】
ポリマ−を微粒子化する方法も限定されないが、乳化重合や懸濁重合等の方法を使用して、重合時に直接微粒子化する方法が好適である。これらの重合方法を採用する場合は自己乳化性を付与し得る特殊構造の極性モノマ−を少量、共重合する手段を採用してもよい。ポリマ−微粒子の形状については特に限定はないが、実質的に球状あるいはラグビ−ボ−ル状のものが好適である。
【0012】
本発明の有機ポリマ−微粒子としては(メタ)アクリル系モノマ−及び/又はスチレン系モノマ−よりなるポリマ−の微粒子を使用することが好ましい。即ち(メタ)アクリル系モノマ−又はスチレン系モノマ−のホモポリマ−、(メタ)アクリル系モノマ−のコポリマ−(コポリマ−以上のタ−ポリマ−も含む。以下同じ)、スチレン系モノマ−のコポリマ−又は(メタ)アクリル系モノマ−とスチレン系モノマ−とのコポリマ−等である。その中でも好ましいのは、架橋タイプの(メタ)アクリル系−スチレン系コポリマ−であり、透明性、滑り性、耐熱性、水滴保持時間等のバランスにおいて優れている。
【0013】
(メタ)アクリル系モノマ−成分としては、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル等のアクリル酸又はそのエステル誘導体、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル等のメタクリル酸又はそのエステル誘導体が挙げられる。これらのモノマ−は一種であっても又は二種以上を併用しても差支えない。また少量であれば、アクリル酸やメタアクリル酸の金属塩、アミド誘導体、ヒドロキシルエチルエステルやジメチルアミノエチルエステル等の特殊な構造のエステル誘導体等を使用しても差支えない。
【0014】
スチレン系モノマ−成分としては、スチレン、メチルスチレン、α−メチルスチレン、β−メチルスチレン等のスチレン又はその誘導体が挙げられる。また全モノマ−成分の20重量%以下であれば、酢酸ビニル、塩化ビニル、塩化ビニリデン、アクリロニトリル、メタアクリロニトリル等の重合性のビニルモノマ−を共重合しても差支えない。架橋方法としては、ジビニルベンゼン、エチレングリコ−ルのジアクリル酸エステルやジメタクリル酸エステル等の多官能性モノマ−を微粒子ポリマ−生成時に共重合させるか又はポリマ−生成後に後架橋する等の方法が挙げられるがこれらに限定されるものではない。
【0015】
本発明における有機ポリマ−微粒子は、前記の方法で測定した水滴保持時間が10秒以上である必要がある。好ましくは1分以上で、より好ましくは5分以上必要である。この水滴保持時間は、有機ポリマ−微粒子の疎水性の度合いを規定したものであり、水滴保持時間が10秒未満の場合は、高透明で、かつ滑り性や耐ブロッキング性の良好なフイルムが得られない。
【0016】
水滴保持時間を10秒以上にするための手段は特に制限されないが、以下に示す方法が推奨される。
▲1▼ 微粒子を構成するポリマ−の構造を最適化する。
▲2▼ 重合方法や微粒子の調整方法を最適化し、微粒子の表面に疎水性基を有した成分を偏在させる。
▲3▼ 乳化重合法や懸濁重合法で直接微粒子化する方法で調製する場合は、重合時に使用する界面活性剤や自己乳化性を付与するモノマ−を最適化する。
▲4▼ 乳化重合法や懸濁重合法で直接微粒子化する方法で調製する場合は、水等の溶媒から微粒子を分離する時の洗浄を充分に行い、界面活性剤等の親水性の添加剤や残留モノマ−を除去する。
▲5▼ 疎水性のモノマ−あるいはポリマ−で微粒子表面を被覆する。
▲6▼ シランカップリング剤やチタネ−トカップリング剤等の表面処理剤で表面処理を行う。
【0017】
本発明における有機ポリマ−微粒子の平均粒径は、0.4〜7.0μmの範囲であることが必要である。0.4μm未満では滑り性の改良効果が小さくなるので好ましくない。また7.0μmを超過すると滑り性の改良効果が飽和に達するが、透明性が悪化するので好ましくない。また、該有機ポリマ−微粒子の粒度分布は、シャ−プであることが透明性、滑り性、耐ブロッキング性を満足するうえで好ましい。なお、該有機ポリマ−微粒子の平均粒径とは、走査型電子顕微鏡で写真撮影し、イメ−ジアナライザ−装置を用いて水平方向のフェレ径を測定し、その平均値で表示したものである。
【0018】
本発明では、フイルム中の有機ポリマ−微粒子の表面層に対する配合割合を、ポリオレフィン100重量部に対して微粒子を0.01〜2重量部とする。好ましくは0.02〜0.5重量部である。有機ポリマ−微粒子の配合量が0.01重量部未満ではフイルムに滑り性及び耐ブロッキング性を付与することが不可能であり、一方2重量部を超過して配合させると、滑り性、耐ブロッキング性は充分与えられるもののフイルムの透明性が著しく阻害されるので好ましくない。
上記した有機ポリマ−微粒子の平均粒径や配合割合の最適値は、ポリオレフィンの種類、フイルムの厚みや構成、延伸の有無等によって変化するので、目的とするフイルム特性に合せて前記した範囲内で適宜任意に設定するのがよい。
上記の有機ポリマ−微粒子の基層を構成するポリオレフィンへの配合の要否は特に制限はないが、基層に配合するとフイルムの透明性が低下するので、透明性が高度に要求される分野に使用するフイルムの場合は有機ポリマ−微粒子の配合は表面層のみに限定するのが好ましい。
【0019】
本発明のポリオレフィン系複合フイルムには、本発明の効果を損なわない範囲であれば、有機ポリマ−微粒子以外の有機や無機の微粒子を併用したり、高級脂肪酸アマイド、高級脂肪酸エステル、ワックス、金属石ケン等の潤滑剤を併用するなどして滑り性を向上させても差支えない。潤滑剤の併用はむしろ好ましい。また通常ポリオレフィン系フイルムに配合される公知の安定剤、帯電防止剤、紫外線吸収剤、加工助剤、可塑剤等の併用も何ら制限を受けない。
上記した有機ポリマ−微粒子や添加剤等をポリオレフィンと混合する方法としては、特に限定されないが、V型ブレンダ、スクリュ−型ブレンダ、ドライブレンダ、リボンブレンダ、ヘンシェルミキサ−等の混合機にて均一混合した後、混練ペレット化する方法を使用するとよい。
【0020】
本発明のポリオレフィン系複合フイルムの積層方法は特に制限を受けず、共押出し法、ラミネ−ト法の何れの方法で実施してもよいが、経済性の面よりすると共押出し法が好適である。本発明においては表面層のフイルムの厚みが0.03〜4μmであることを要する。更に0.05〜3μmがより好適である。0.03μm未満では滑り性や耐ブロッキング性の向上効果が充分でなく、好ましくない。逆に4μmを越えると滑り性や耐ブロッキング性の向上効果が飽和し、かつ透明性が低下するので好ましくない。本発明における総フイルム厚みはその用途に応じて決められるが、通常6〜100μm、好ましくは10〜50μmの範囲である。
【0021】
本発明の複合フイルムは、単に押出成形した未延伸のキャスティングフイルムでも、該キャスティングフイルムを一軸又は二軸方向に延伸した延伸フイルムでもよく、二軸延伸フイルムは本発明の効果が顕著に発現されるので特に好適である。更に本発明のフイルムに対して、コロナ放電処理、プラズマ処理、紫外線照射処理等、接着性を向上させる表面処理を施すことは用途展開上有用である。
【0022】
以下実施例によって本発明を更に詳細説明するが、下記実施例によって本発明がこれに限定されるものではなく、前記又は後記に記載した趣旨を逸脱しない範囲で変更、実施することはすべて本発明の技術範囲に包含される。なお実施例に用いた測定方法は次の通りである。
(1) 曇価
JIS−K6714に準じ、東洋精機製ヘ−ズテスタ−Jで測定した。
(2) 狭角拡散透過値
東洋精機製作所製の視覚透明度試験機を用いて測定した。測定値が小さい程、透明度が高いことを示している。
(3) 摩擦係数
20℃×65%RHにおいてASTM−D1894に準じ測定した。
(4) 耐ブロッキング性
フイルムをカッタ−で80mm×120mmに裁断し、この裁断片、2枚を長手方向に上下に20mmずつずらして重ねてサンプルとする。このサンプルをタイプ用紙と交互に5組重ね合せ、ガラス板で挾んだ後2Kgの加重をかけ50℃で48時間放置する。サンプルを取出して放冷し、20mm幅で長手方向に再裁断し試験片とし、試験片を引張り速度220mm/分で剪断応力を測定した。
【0023】
【実施例1】
基層用レジンとして、メルトインデックス2.5g/10分のポリプロピレン100重量部に対してグリセリン樹脂酸エステル0.3重量部及びエルカ酸アミド0.3重量部を混合した組成物を表面層用レジンとしてメルトインデックス2.5g/10分のポリプロピレン100重量部に対して、水滴保持時間が10分以上で、平均粒径が1.1μmのほぼ単分散の粒径分布を示す球状の架橋アクリル−スチレン系共重合体粒子〔メチルメタクリレ−ト/n−ブチルアクリレ−ト/スチレン/ジビニルベンゼン=36/27/36/1(重量比)からなるモノマ−成分を乳化重合法で重合調製し、乳化液から共重合体粒子を分離する際に水洗を5回繰返して微粒子表面に付着している界面活性剤を充分に除去する。〕0.15重量部、グリセリン樹脂酸エステル0.3重量部及びエルカ酸アミド0.3重量部を混合した組成物を用いて、上記基層用レジン及び表面層用レジンをそれぞれ別々の押出し機で溶融させ、この溶融体をダイ間で合流させて基層の両面に表面層を積層した三層構成の溶融体を20℃の冷却ロ−ルで急冷して、総厚さ0.90mmの未延伸シ−トを得た。〔(表面層/基層/表面層)の厚み比=1/23/1〕。この未延伸シ−トを、縦延伸機のロ−ル周速差を利用して、延伸温度40℃で縦方向に4.5倍延伸し、引続きテンタ−式延伸機により延伸温度155℃で横方向に8倍延伸した。次いで160℃で熱処理を行い、厚さ約25μmの二軸延伸フイルムとした後、片面にコロナ放電処理を施した。得られたフイルムの特性値を〔表1〕に示す。
【0024】
【表1】
【0025】
【比較例1】
実施例1において、乳化液から共重合体粒子を分離する際の水洗を1回のみとして得た水滴保持時間が2秒以内である架橋アクリル−スチレン系共重合体粒子(平均粒径、粒度分布、粒子形状、粒子組成は実施例1と同じ)を用いる以外は実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0026】
【比較例2】を削除します。
【0027】
【比較例3】
実施例1と同じ方法で水洗した水滴保持時間が10分以上の平均粒径が8μmのほぼ単分散の粒径分布を示す球状の架橋アクリル−スチレン系共重合体微粒子(組成は実施例1と同じ)を用いる以外は実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0028】
【比較例4】を削除します。
【0029】
【比較例5】を削除します。
【0030】
【比較例6】
実施例1の方法において、基層用樹脂に対しても表面層用樹脂に配合したのと同じ架橋アクリル−スチレン系共重合体微粒子をポリプロピレン100重量部に対して0.15重量部を配合するよう変更する以外は、実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0031】
【実施例2】
実施例1の方法において、架橋アクリル−スチレン系共重合体微粒子に替えて、水滴保持時間が8分の平均粒径が1.7μmのほぼ単分散の粒度分布を示す球状の架橋アクリル系微粒子〔組成;メチルメタクリレ−ト/トリメチロ−ルプロパントリメタクリレ−ト=98/2(重量比)〕を用い、かつ、その添加量を0.10重量部とする以外は、実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0032】
【比較例7】
実施例2の方法において、水滴保持時間が2秒以内の架橋アクリル系粒子を用いる以外は、実施例2と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0033】
【比較例8】
実施例2の方法において、基層用樹脂にも表面層用樹脂に配合したと同じ架橋アクリル系粒子をポリプロピレン100重量部に対して0.10重量部配合するよう変更する以外は、実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0034】
【比較例9】
比較例7の方法において、基層用樹脂にも表面層用樹脂に配合したと同じ架橋アクリル系粒子をポリプロピレン100重量部に対して0.10重量部を配合するよう変更する以外は、比較例7と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0035】
【実施例3】
実施例1の方法において、架橋アクリル−スチレン系共重合体粒子に替えて、ポリマ−型のシランカップリング剤で表面処理して得た水滴保持時間が10分以上、平均粒径が1.3μmのほぼ単分散の粒径分布を示す球状の架橋ポリスチレン系粒子〔懸濁重合で調製、組成;スチレン/ジビニルベンゼン=98/2(重量比)〕を用いる以外は、実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0036】
【比較例10】
実施例3の方法において、架橋ポリスチレン系粒子の表面処理を行わず、水滴保持時間が2秒以内の粒子を用いる以外は、実施例3と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0037】
【比較例11】
実施例3の方法において、基層用樹脂にも表面層用樹脂に配合したと同じ架橋スチレン系粒子をポリプロピレン100重量部に対して0.15重量部を配合するよう変更する以外は、実施例1と同じ方法でフイルムを得た。特性値を〔表1〕に示す。
【0038】
【比較例12】を削除します。
【0039】
実施例1〜3で得られた本発明のフイルムは、何れも優れた透明性と、良好な滑り性及び耐ブロッキング性を示し、著しく高品質であった。一方、比較例1で得られたフイルムは、透明性及び耐ブロッキング性に劣り低品質であった。なお透明性の評価方法として一般に用いられている「曇価」では、比較例1のフイルムは実施例のものとあまり大きな差がないが、肉眼観察での透明性との相関性が高い狭角拡散透過値では著しく劣っていることがわかる。
【0040】
比較例2で得られたフイルムは、透明性は良好であるが、耐ブロッキング性に劣り、比較例3,7,9,10,及び12で得られたフイルムは透明性及び耐ブロッキング性に劣り、比較例4で得られたフイルムは滑り性及び耐ブロッキング性に劣り、比較例5,6,8及び11で得られたフイルムは透明性に劣っており、何れも低品質であった。
【0041】
【発明の効果】
本発明のポリオレフィン系フイルムは、複層構成で、かつ水滴保持時間の長い特定の表面特性を有した有機ポリマ−微粒子を特定量配合した構成であるので、透明性と共に、滑り性及び耐ブロッキング性にも優れており、例えば各種の包装用材料として広く利用することができる。特に透明性に優れているが故に透明性が高度に要求される包装用分野に好適に使用することができる。[0001]
[Industrial applications]
The present invention relates to a polyolefin-based composite film which is excellent in transparency, slipperiness and blocking resistance and is suitably used in the field of packaging or other fields where transparency is highly required.
[0002]
[Prior art]
As a method of improving the slipperiness and blocking resistance of a conventional polyolefin film, for example, adding inorganic fine particles such as silica, calcium carbonate, clay, titanium white, and zeolite, and changing the surface properties of the film to prevent blocking. (JP-B-52-16134, JP-A-3-9938). However, the fine particles of the inorganic substance are easily aggregated, the transparency of the polyolefin composite film is impaired due to a large difference in the refractive index from the polyolefin resin, and the affinity between the polypropylene resin and the inorganic substance is low. Voids are generated around the substance and the transparency is reduced.
[0003]
Therefore, it is impossible to add a sufficient amount of the particulate inorganic substance to give satisfactory slipperiness and blocking resistance to a stretched film requiring transparency for the above-mentioned reason. In order to compensate for the drawbacks of the polyolefin film to which the inorganic substance of these fine particles is added, as a polypropylene composite film to which fine particles of an organic polymer are added, a cross-linked structure having a particle size of 3 to 40 μ with respect to the polypropylene resin and a melting point A polymer fine powder having no polymer is uniformly mixed in an amount of 0.02 to 0.8% by weight with respect to a polypropylene resin, melt-extruded, cooled, and then stretched at least uniaxially. No. 57-64522), and for a stretched polyolefin film, a condensed resin having a spherical triazine ring having an average particle diameter of 0.5 to 10 μm is used in an amount of 0.01 to 0.1 wt. % Of a stretched polyolefin film which is stretched at least 4 times or more in a uniaxial direction (Japanese Unexamined Patent Publication No. 62-39219).
[0004]
However, according to the study results of the present inventors, conventional polyolefin-based composite films using organic polymer fine particles are excellent in transparency and scratch resistance as compared with polyolefin-based composite films using inorganic fine particles, The balance between the transparency, the slipperiness and the blocking resistance is insufficient, and has not yet reached a level satisfying high market requirements.
[0005]
[Problems to be solved by the invention]
As described above, for the polyolefin-based composite film having excellent transparency, slipperiness and blocking resistance, not only the conventional method of adding inorganic fine particles, but also the conventional method of using organic polymer particles. As described above, there is a problem that the polyolefin composite film is insufficient, and the level of transparency, slipperiness and blocking resistance of the polyolefin composite film does not reach a level that satisfies a high market demand. That is, when the amount of fine particles to be added to the polyolefin-based composite film is reduced in order to achieve a high degree of transparency, slipperiness and blocking resistance are deteriorated, and workability in the film manufacturing process and processing process is problematic. In contrast, when the properties of the slipping property and the blocking resistance are satisfied, the transparency is reduced, so that the polyolefin composite film is excellent in both the transparency and the properties opposite to the slipping property and the blocking resistance. Has not yet been obtained.
In view of the above, an object of the present invention is to provide a polyolefin-based composite film having excellent transparency, slipperiness, and blocking resistance.
[0006]
[Means for Solving the Problems]
A first aspect of the present invention is an organic polymer fine particle having an average particle size of 0.4 to 7.0 μm and a water droplet holding time of 10 seconds or more on at least one surface of a base film of a composite film formed of a polyolefin-based polymer. A polyolefin-based composite comprising a multilayer and a film of a polyolefin-based polymer containing 0.01 to 2 parts by weight with respect to 100% by weight of the polyolefin-based polymer whose surface layer is a polyolefin-based composite. It is about film.
[0007]
Secondly, in the first aspect of the present invention, the organic polymer fine particles are a monomer containing an acrylic monomer or a methacrylic monomer (abbreviated as (meth) acrylic monomer) and / or a styrene monomer. A polyolefin-based composite film, which is a polymer comprising components.
[0008]
A third aspect of the present invention relates to the polyolefin composite film of the first and second aspects, wherein the thickness of the film of the surface layer is 0.03 to 4 μm.
Here, the water drop holding time is
The organic polymer fine particles were sandwiched between two biaxially stretched polypropylene films on a horizontal and smooth table, and the upper film was lightly pressed by hand to form a smooth organic polymer fine particle layer having a thickness of 2 mm. Then, gently remove the upper film. A drop of water having a diameter of 2 mm is dropped from a height of 1 cm onto the surface of the obtained organic polymer fine particle layer with a spoid, and the time until the water drop is absorbed by the organic polymer fine particle layer and disappears.
[0009]
Examples of the polyolefin constituting the polyolefin composite film of the present invention include a homopolymer such as propylene, ethylene, butene and 4-methylpentene-1 or a mixture of these copolymers for both the base layer and the surface layer. The types of the polyolefins constituting the base layer and the surface layer may be the same or different, and any type may be used.
[0010]
The organic polymer fine particles used in the present invention are not particularly limited as long as they are non-melting at the melt molding temperature of the polyolefin and have heat resistance to withstand the same temperature, and are obtained by an addition polymerization method. And those obtained by a polycondensation or polyaddition reaction method. The polymer constituting the organic polymer fine particles may be a non-crosslinked type or a crosslinked type, but the crosslinked type is more preferred from the viewpoint of heat resistance.
[0011]
The method of forming the polymer into fine particles is not limited, but a method of directly forming fine particles during polymerization using a method such as emulsion polymerization or suspension polymerization is preferred. When these polymerization methods are employed, a means for copolymerizing a small amount of a polar monomer having a special structure capable of imparting self-emulsification may be employed. The shape of the polymer fine particles is not particularly limited, but is preferably substantially spherical or rugby ball-shaped.
[0012]
As the organic polymer fine particles of the present invention, it is preferable to use polymer fine particles composed of a (meth) acrylic monomer and / or a styrene monomer. That is, a homopolymer of a (meth) acrylic monomer or a styrene monomer, a copolymer of a (meth) acrylic monomer (including a copolymer higher than a copolymer, the same applies hereinafter), and a copolymer of a styrene monomer. Or a copolymer of a (meth) acrylic monomer and a styrene monomer. Among them, preferred is a cross-linked (meth) acrylic-styrene-based copolymer, which is excellent in balance among transparency, slipperiness, heat resistance, water drop holding time and the like.
[0013]
Examples of the (meth) acrylic monomer component include acrylic acid such as acrylic acid, methyl acrylate, ethyl acrylate, and butyl acrylate, and ester derivatives thereof, and methacrylic acid, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Methacrylic acid or its ester derivative is mentioned. These monomers may be used alone or in combination of two or more. If the amount is small, a metal salt of acrylic acid or methacrylic acid, an amide derivative, or an ester derivative having a special structure such as hydroxylethyl ester or dimethylaminoethyl ester may be used.
[0014]
Examples of the styrene monomer component include styrene such as styrene, methylstyrene, α-methylstyrene, and β-methylstyrene, and derivatives thereof. If the content is 20% by weight or less of the total monomer components, a polymerizable vinyl monomer such as vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile or the like may be copolymerized. Examples of the cross-linking method include a method of copolymerizing a polyfunctional monomer such as divinyl benzene or diglyceric acid ester of ethylene glycol or dimethacrylic acid ester at the time of forming the fine particle polymer, or a method of post-crosslinking after forming the polymer. Examples include, but are not limited to:
[0015]
The organic polymer fine particles in the present invention must have a water droplet retention time of at least 10 seconds as measured by the above method. It is preferably at least 1 minute, more preferably at least 5 minutes. The water droplet holding time defines the degree of hydrophobicity of the organic polymer fine particles. If the water droplet holding time is less than 10 seconds, a film that is highly transparent and has good slipperiness and blocking resistance can be obtained. I can't.
[0016]
Means for setting the water droplet holding time to 10 seconds or longer is not particularly limited, but the following method is recommended.
(1) Optimize the structure of the polymer constituting the fine particles.
{Circle around (2)} Optimizing the polymerization method and the method for preparing fine particles, and unevenly distributing the component having a hydrophobic group on the surface of the fine particles.
{Circle around (3)} When the emulsion is prepared by a method of directly forming fine particles by an emulsion polymerization method or a suspension polymerization method, a surfactant used at the time of polymerization and a monomer for imparting self-emulsifying properties are optimized.
(4) When preparing by a method of directly forming fine particles by an emulsion polymerization method or a suspension polymerization method, sufficiently wash the fine particles when separating them from a solvent such as water, and use a hydrophilic additive such as a surfactant. And residual monomers are removed.
(5) The surface of the fine particles is coated with a hydrophobic monomer or polymer.
{Circle around (6)} The surface is treated with a surface treating agent such as a silane coupling agent or a titanate coupling agent.
[0017]
The average particle size of the organic polymer fine particles in the present invention needs to be in the range of 0.4 to 7.0 μm. If the thickness is less than 0.4 μm, the effect of improving the slip property is undesirably reduced. On the other hand, if the thickness exceeds 7.0 μm, the effect of improving the slip property reaches saturation, but the transparency is unfavorably deteriorated. Further, the particle size distribution of the organic polymer fine particles is preferably a sharp in order to satisfy transparency, slipperiness and blocking resistance. The average particle size of the organic polymer fine particles was obtained by taking a photograph with a scanning electron microscope, measuring the Feret diameter in the horizontal direction using an image analyzer, and displaying the average value. .
[0018]
In the present invention, the mixing ratio of the organic polymer fine particles in the film to the surface layer is set to 0.01 to 2 parts by weight based on 100 parts by weight of the polyolefin. Preferably it is 0.02-0.5 weight part. If the amount of the organic polymer fine particles is less than 0.01 part by weight, it is impossible to impart slipperiness and blocking resistance to the film. Although the properties are sufficiently provided, the transparency of the film is significantly impaired, which is not preferable.
The optimum value of the average particle diameter and the blending ratio of the above-mentioned organic polymer-fine particles varies depending on the type of the polyolefin, the thickness and the structure of the film, the presence or absence of stretching, etc., so that it is within the range described above in accordance with the intended film characteristics. It is better to set it arbitrarily.
The necessity of blending the above organic polymer fine particles with the polyolefin constituting the base layer is not particularly limited, but if it is blended in the base layer, the transparency of the film is reduced. Therefore, it is used in a field where transparency is highly required. In the case of a film, the compounding of the organic polymer fine particles is preferably limited to only the surface layer.
[0019]
In the polyolefin-based composite film of the present invention, organic or inorganic fine particles other than the organic polymer fine particles may be used together, or higher fatty acid amides, higher fatty acid esters, waxes, metal stones may be used as long as the effects of the present invention are not impaired. It is possible to improve the slipperiness by using a lubricant such as Ken together. The use of a lubricant is rather preferred. In addition, there are no restrictions on the use of known stabilizers, antistatic agents, ultraviolet absorbers, processing aids, plasticizers, and the like, which are usually added to the polyolefin film.
The method for mixing the above-mentioned organic polymer fine particles and additives with the polyolefin is not particularly limited, but is uniformly mixed with a mixer such as a V-type blender, a screw-type blender, a drive render, a ribbon blender, and a Henschel mixer. Then, a method of kneading and pelletizing may be used.
[0020]
The method for laminating the polyolefin-based composite film of the present invention is not particularly limited, and may be carried out by any of a coextrusion method and a lamination method. However, from the viewpoint of economy, the coextrusion method is preferred. . In the present invention, the film thickness of the surface layer needs to be 0.03 to 4 μm. Further, the thickness is more preferably 0.05 to 3 μm. If it is less than 0.03 μm, the effect of improving the slipperiness and the blocking resistance is not sufficient, which is not preferable. Conversely, if it exceeds 4 μm, the effect of improving the slipperiness and the blocking resistance is saturated, and the transparency is undesirably reduced. The total film thickness in the present invention is determined according to the use, but is usually in the range of 6 to 100 μm, preferably 10 to 50 μm.
[0021]
The composite film of the present invention may be an unstretched casting film simply extruded, or a stretched film obtained by stretching the casting film in a uniaxial or biaxial direction. This is particularly preferred. Further, it is useful in application development to subject the film of the present invention to a surface treatment for improving adhesiveness, such as a corona discharge treatment, a plasma treatment, and an ultraviolet irradiation treatment.
[0022]
Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples, and all changes and implementations within the scope of the above or the following description are possible without departing from the scope of the present invention. Within the technical scope of The measuring method used in the examples is as follows.
(1) Haze value According to JIS-K6714, the haze value was measured with a haze tester J manufactured by Toyo Seiki.
(2) Narrow angle diffuse transmission value Measured using a visual transparency tester manufactured by Toyo Seiki Seisaku-sho, Ltd. The smaller the measured value, the higher the transparency.
(3) Coefficient of friction was measured at 20 ° C. × 65% RH according to ASTM-D1894.
(4) The anti-blocking film is cut into a piece of 80 mm × 120 mm with a cutter, and two pieces of the cut pieces are overlapped with each other by being shifted vertically by 20 mm in the longitudinal direction to form a sample. Five sets of this sample are alternately stacked with type paper, sandwiched between glass plates, and then subjected to a load of 2 kg and left at 50 ° C. for 48 hours. The sample was taken out, allowed to cool, recut in the longitudinal direction at a width of 20 mm to obtain a test piece, and the test piece was measured for shear stress at a tensile speed of 220 mm / min.
[0023]
Embodiment 1
As the resin for the base layer, a composition obtained by mixing 0.3 parts by weight of glycerin resin acid ester and 0.3 parts by weight of erucamide with 100 parts by weight of polypropylene having a melt index of 2.5 g / 10 minutes was used as the resin for the surface layer. Spherical crosslinked acryl-styrene system having a water droplet retention time of 10 minutes or more and an average particle size of 1.1 μm and a substantially monodisperse particle size distribution with respect to 100 parts by weight of polypropylene having a melt index of 2.5 g / 10 minutes. Copolymer particles [A monomer component composed of methyl methacrylate / n-butyl acrylate / styrene / divinylbenzene = 36/27/36/1 (weight ratio) is polymerized by an emulsion polymerization method, and is prepared from the emulsion. When separating the copolymer particles, washing with water is repeated 5 times to sufficiently remove the surfactant adhering to the surface of the fine particles. Using a composition obtained by mixing 0.15 parts by weight, 0.3 parts by weight of glycerin resin acid ester and 0.3 parts by weight of erucamide, the above resin for the base layer and the resin for the surface layer are separately extruded. It is melted, the melt is joined between dies, and a three-layer melt obtained by laminating a surface layer on both sides of a base layer is quenched by a cooling roll at 20 ° C., and is unstretched to a total thickness of 0.90 mm. A sheet was obtained. [Thickness ratio of (surface layer / base layer / surface layer) = 1/23/1]. This unstretched sheet is stretched 4.5 times in the machine direction at a stretching temperature of 40 ° C. by utilizing a difference in roll peripheral speed of a longitudinal stretching machine, and subsequently stretched at a stretching temperature of 155 ° C. by a tenter type stretching machine. The film was stretched 8 times in the transverse direction. Next, heat treatment was performed at 160 ° C. to form a biaxially stretched film having a thickness of about 25 μm, and then one surface was subjected to a corona discharge treatment. Table 1 shows the characteristic values of the obtained films.
[0024]
[Table 1]
[0025]
[Comparative Example 1]
In Example 1, crosslinked acrylic-styrene-based copolymer particles (average particle size, particle size distribution) obtained by performing water washing only once when separating the copolymer particles from the emulsion and having a water droplet holding time of 2 seconds or less , A particle shape and a particle composition were the same as in Example 1, except that a film was obtained in the same manner as in Example 1. The characteristic values are shown in [Table 1].
[0026]
[Comparative Example 2] is deleted.
[0027]
[Comparative Example 3]
Spherical crosslinked acryl-styrene copolymer fine particles exhibiting a substantially monodisperse particle size distribution having an average particle size of 8 μm and a water droplet retention time of 10 minutes or more washed with water in the same manner as in Example 1 (the composition is the same as that of Example 1). A film was obtained in the same manner as in Example 1 except that the same was used. The characteristic values are shown in [Table 1].
[0028]
[Comparative Example 4] is deleted.
[0029]
[Comparative Example 5] is deleted.
[0030]
[Comparative Example 6]
In the method of Example 1, 0.15 parts by weight of the same crosslinked acryl-styrene-based copolymer fine particles as the resin for the surface layer was added to the resin for the base layer, relative to 100 parts by weight of polypropylene. A film was obtained in the same manner as in Example 1, except for the change. The characteristic values are shown in [Table 1].
[0031]
Embodiment 2
In the method of Example 1, in place of the crosslinked acrylic-styrene-based copolymer fine particles, spherical crosslinked acrylic fine particles exhibiting a substantially monodispersed particle size distribution with an average particle size of 1.7 μm for a water droplet holding time of 8 minutes [ Composition: Methyl methacrylate / trimethylolpropane trimethacrylate = 98/2 (weight ratio)] and the amount added was 0.10 parts by weight, the same as Example 1. A film was obtained by the method. The characteristic values are shown in [Table 1].
[0032]
[Comparative Example 7]
A film was obtained in the same manner as in Example 2, except that the crosslinked acrylic particles having a water droplet holding time of 2 seconds or less were used. The characteristic values are shown in [Table 1].
[0033]
[Comparative Example 8]
The method of Example 2 was the same as that of Example 1, except that the same cross-linked acrylic particles as used in the resin for the base layer were also added to the resin for the surface layer in an amount of 0.10 parts by weight based on 100 parts by weight of polypropylene. A film was obtained in the same manner. The characteristic values are shown in [Table 1].
[0034]
[Comparative Example 9]
Comparative Example 7 was the same as Comparative Example 7 except that the same crosslinked acrylic particles as those used in the base layer resin were also added to the resin for the surface layer so that 0.10 parts by weight was added to 100 parts by weight of polypropylene. A film was obtained in the same manner as described above. The characteristic values are shown in [Table 1].
[0035]
Embodiment 3
In the method of Example 1, a water droplet holding time obtained by performing a surface treatment with a polymer-type silane coupling agent in place of the crosslinked acrylic-styrene copolymer particles is 10 minutes or more, and the average particle diameter is 1.3 μm. In the same manner as in Example 1 except that spherical cross-linked polystyrene-based particles (prepared by suspension polymerization, composition; styrene / divinylbenzene = 98/2 (weight ratio)) exhibiting a substantially monodisperse particle size distribution of I got a film. The characteristic values are shown in [Table 1].
[0036]
[Comparative Example 10]
A film was obtained in the same manner as in Example 3, except that the surface treatment of the crosslinked polystyrene-based particles was not performed and the particles having a water droplet holding time of 2 seconds or less were used. The characteristic values are shown in [Table 1].
[0037]
[Comparative Example 11]
Example 1 was repeated except that the same crosslinked styrene-based particles as used in the resin for the base layer and in the resin for the surface layer were added in an amount of 0.15 parts by weight with respect to 100 parts by weight of polypropylene in the method of Example 3. A film was obtained in the same manner as described above. The characteristic values are shown in [Table 1].
[0038]
[Comparative Example 12] is deleted.
[0039]
Each of the films of the present invention obtained in Examples 1 to 3 exhibited excellent transparency, good sliding properties and blocking resistance, and was extremely high in quality. On the other hand, the film obtained in Comparative Example 1 was inferior in transparency and blocking resistance and was of low quality. In the “haze value” which is generally used as a method of evaluating transparency, the film of Comparative Example 1 does not have much difference from that of the example, but has a high narrow-angle which has a high correlation with the transparency by visual observation. It can be seen that the diffuse transmission value is remarkably inferior.
[0040]
The film obtained in Comparative Example 2 has good transparency but is inferior in blocking resistance, and the films obtained in Comparative Examples 3, 7, 9, 10, and 12 are inferior in transparency and blocking resistance. The film obtained in Comparative Example 4 was inferior in slipperiness and blocking resistance, and the films obtained in Comparative Examples 5, 6, 8 and 11 were inferior in transparency, and all were of low quality.
[0041]
【The invention's effect】
The polyolefin film of the present invention has a multi-layer structure, and a structure in which a specific amount of organic polymer fine particles having a specific surface property having a long water droplet holding time is blended, so that, together with transparency, slipperiness and blocking resistance And can be widely used, for example, as various packaging materials. Particularly, since it is excellent in transparency, it can be suitably used in the field of packaging where transparency is highly required.
Claims (3)
ここに(メタ)アクリル系モノマ−とはアクリル系モノマ−又はメタクリル系モノマ−の略称である。2. The polyolefin composite film according to claim 1, wherein the organic polymer fine particles are a polymer comprising a monomer component containing a (meth) acrylic monomer and / or a styrene monomer.
Here, the (meth) acrylic monomer is an abbreviation for an acrylic monomer or a methacrylic monomer.
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JP21810494A JP3551485B2 (en) | 1994-08-19 | 1994-08-19 | Polyolefin composite film |
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JP21810494A JP3551485B2 (en) | 1994-08-19 | 1994-08-19 | Polyolefin composite film |
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TW200920597A (en) * | 2007-08-28 | 2009-05-16 | Toyo Boseki | Polypropylene series resin laminated film and manufacturing method thereof |
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