JP4540858B2 - Porous film and method for producing the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、多孔性フィルム及びその製造方法に関する。詳しくは、特定の混合樹脂を含む樹脂組成物から成形された多孔性フィルム及びその製造方法であって、成形後に高速で巻き取った場合であっても破れ等の欠陥が極めて少ない多孔性フィルム及びその製造方法に関する。
【０００２】
【従来の技術】
これまで、ポリオレフィン樹脂に無機充填剤及び各種油、ワックス等を添加したフィルムを少なくとも一軸方向に延伸し、無機充填材とポリオレフィンとの間で界面剥離が起こさせることによりボイドを発生させる多孔性フィルムの製造方法が多数提案されている（例えば、特開平７−２６０７６号公報、特開平９−２５３７２号公報等）。これらの多孔性フィルムは、内部に多数の微小なボイドを有しているため、高い透湿度を有しながらも液体を透過させることはない。この性質を生かし、これまで使い捨て紙オムツなどの衛生材料、建築材料、反射フィルム、電池セパレーター等多岐に幅広く利用されている。
【０００３】
ただし、このような無機充填材を多く含むフィルムを製膜する際の問題点は、高速製膜が困難であることである。すなわち、無機充填材を含むためにドローダウン性が悪くなり、高速製膜時にはフィルムの破断、破れなどが生じる。これらの理由により、従来の技術ではせいぜいライン速度１６０ｍ／分程度の巻き取り速度が限界であった。そのため、生産性が低かった。この傾向は、薄肉時に著しく、例えば、目付けが２０ｇ／ｍ2程度のときには、均一な特性を有する多孔性フィルムを高速製膜することは従来困難であった。
【０００４】
【発明が解決しようとする課題】
本発明の目的は、上記問題に鑑み、高速で巻き取った場合であっても、破れ等の欠陥がなく、且つ、透湿度等の本来の特性を従来品と同等に維持された多孔性フィルム、及びその製造方法を提供することにある。
【０００５】
【課題を解決するための手段】
本発明者らは、鋭意検討した結果、メタロセン触媒を用いて製造されたエチレン−α−オレフィン共重合体（Ａ）、チーグラー触媒を用いて製造されたエチレン−α−オレフィン共重合体（Ｂ）、及び、分岐状低密度ポリエチレン（Ｃ）をそれぞれ特定量含む混合樹脂に無機充填材を所定量添加した樹脂組成物を原料として用いることにより、上記課題が解決できることを見出し、本発明に到った。
【０００６】
すなわち、本発明は、メルトインデックス０．５〜１０ｇ／１０分、密度０．９０５〜０．９４５ｇ／ｃｍ3である、メタロセン触媒を用いて製造されたエチレン−α−オレフィン共重合体（Ａ）２０〜９８重量％、メルトインデックス０．５〜１０ｇ／１０分、密度０．９０５〜０．９４５ｇ／ｃｍ3である、チーグラー触媒を用いて製造されたエチレン−α−オレフィン共重合体（Ｂ）１〜７９重量％、及び、メルトインデックス０．１〜１０ｇ／１０分、密度０．９１〜０．９３５ｇ／ｃｍ3である分岐状低密度ポリエチレン（Ｃ）１〜８重量％を含む樹脂１００重量部に対し、無機充填材（Ｄ）５０〜５００重量部を含む樹脂組成物から形成された多孔性フィルムであり、且つ、温度１９０℃、引き取り速度２００ｍ／分における溶融張力が０．５〜４ｇ、溶融伸度が少なくとも８００％である多孔性フィルムである。
【０００７】
本発明に用いる好ましい樹脂組成物として、前記混合樹脂１００重量部に対し、硬化ヒマシ油及び脱水ヒマシ油から選ばれた少なくとも一種類の化合物０．１〜１２重量部を含む前記樹脂組成物が挙げられる。
【０００８】
本発明に係わる上記多孔性フィルムは、前記樹脂組成物を１８０〜２８０℃において混練、溶融してフィルム成形した後、室温〜樹脂の軟化点の温度範囲において、少なくとも一軸方向に１．１〜４倍延伸し、次いで、室温近傍の温度まで冷却した後、最大速度３００ｍ／分で巻き取ることにより製造される。好ましくは、延伸後、樹脂の軟化温度以上、融点未満の温度範囲において、０．１〜１００秒間熱処理することにより製造される。
【０００９】
本発明の多孔性フィルムは、上記（Ａ）、（Ｂ）及び（Ｃ）の３樹脂を特定の重量割合で含む混合樹脂を主原料とすることに特徴がある。そのため、フィルム成形後、最大速度３００ｍ／分で巻き取った場合であっても破れ等の欠陥を有することがなく、且つ、透湿度等の本来の特性が従来品と同レベルもしくはそれ以上に維持された多孔性フィルムである。
【００１０】
尚、本発明における溶融張力及び溶融伸度は、後述の実施例に記載した方法により測定した値を意味する。
【００１１】
【発明の実施の形態】
以下、本発明について詳細に述べる。本発明の多孔性フィルムは、ポリオレフィン樹脂（Ａ）、（Ｂ）及び（Ｃ）の３種類を特定の重量比で含む混合樹脂、及び無機充填材を含む樹脂組成物、好ましくは、第３成分として硬化ヒマシ油、脱水ヒマシ油、またはこれらの混合物を含む樹脂組成物を二軸もしくは一軸の混練機でコンパウンドとし、その後、溶融成形してフィルムとなし、得られたフィルムを一軸方向または二軸方向に所定の倍率で延伸することにより製造される。
【００１２】
本発明に用いる、メタロセン触媒を用いて重合されたエチレン−α−オレフィン共重合体（Ａ）としては、α−オレフィン単位を０．５〜１０モル％含むエチレン−α−オレフィン共重合体が挙げられる。これらの内、メルトインデックスが０．５〜１０ｇ／１０分、密度が０．９０５〜０．９４５ｇ／ｃｍ3であるものが好ましい。更に好ましくは、メルトインデックスが１〜１０ｇ／１０分、密度が０．９０５〜０．９３ｇ／ｃｍ3のものである。密度が上記の範囲を超えるものはフィルムが硬くなり好ましくなく、上記の範囲を下回るものは通気性が悪化し成形前、成形時にブロッキングが起こる可能性が高くなる。また、温度上昇溶離分別試験による溶出曲線の相対強度ピークが、溶出温度７０〜９０℃の範囲に一個、９０℃を超える範囲に一個存在し、且つ、数平均分子量に対する重量平均分子量の比が１．５〜５．５であるエチレン−α−オレフィン共重合体が好ましい。
【００１３】
エチレン−α−オレフィン共重合体のα−オレフィン単位としては、１−ブテン、１−ペンテン、１−ヘキセン、４−メチル−１−ペンテン、１−ヘプテン、１−オクテン、１−ノネンが挙げられる。１−ヘキセン、４−メチル−１−ペンテン、１−オクテンがより好ましい。市販品としては、三井化学（株）製、商品名：エボリューＳＰ１５４０、同エボリューＳＰ２０４０、同エボリューＳＰ２５２０等が挙げられる。以下、上記共重合体（Ａ）をメタロセン触媒ポリエチレンという。
【００１４】
チーグラー触媒を用いて重合されたエチレン−α−オレフィン共重合体（Ｂ）としては、α−オレフィン単位を０．５〜１０モル％含むエチレン−α−オレフィン共重合体が挙げられる。これらの内、メルトインデックス０．５〜１０ｇ／１０分、密度０．９０５〜０．９４５ｇ／ｃｍ3であるものが好ましい。更に好ましくは、メルトインデックスが１〜１０ｇ／１０分、密度が０．９１〜０．９３ｇ／ｃｍ3のものである。密度が上記の範囲を超えるものはフィルムが硬くなり触感が好ましくなく、上記以下の密度のものを添加すると通気性が悪化し通気性フィルムとして好ましくない。さらに、成型時にブロッキングが起こる可能性が高くなる。また、数平均分子量に対する重量平均分子量の比が２．５〜５．５であるエチレン−α−オレフィン共重合体が好ましい。市販品としては、三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、同２０１００Ｊ、同２５２０Ｆ等が挙げられる。以下、上記共重合体（Ｂ）をチーグラー触媒ポリエチレンという。
【００１５】
また、分岐状低密度ポリエチレン（Ｃ）は、高圧法により合成された樹脂であり、オートクレーブ法によるものでも、チューブラー法によるものでもよい。これらの内、メルトインデックス０．１〜１０ｇ／１０分、密度０．９１〜０．９３５ｇ／ｃｍ3であるものが好ましい。更に好ましくは、メルトインデックスが０．３〜８ｇ／１０分、密度が０．９１５〜０．９３ｇ／ｃｍ3のものである。また、共重合体として酢酸ビニル単位を６重量％以下含むものでもよい。市販品としては、三井化学（株）製、商品名：ミラソン１４、同Ｆ９６７、同１０２等が挙げられる。以下、上記ポリエチレン（Ｃ）を分岐状低密度ポリエチレンという。
【００１６】
本発明の多孔性フィルムを形成する樹脂は、上記メタロセン触媒ポリエチレン（Ａ）、上記チーグラー触媒ポリエチレン（Ｂ）、及び、上記分岐状低密度ポリエチレン（Ｃ）の混合物により構成される。本発明においては、特に、メタロセン触媒ポリエチレンとチーグラー触媒ポリエチレンを混合している点が重要である。チーグラー触媒ポリエチレン（Ｂ）は、多孔性フィルムの基材として非常に有用なものであるが、メタロセン触媒ポリエチレン（Ａ）に対し、一般的に高速製膜性が劣る。そこで、メタロセン触媒ポリエチレン（Ａ）を用いる訳であるが、このポリエチレンは成形機と相性が悪く、厚みムラ及び均一延伸性に問題が生じる。本発明は、かかる成形性に係わる問題点をチーグラー触媒ポリエチレン（Ｂ）を併用することにより改良するものである。また、均一延伸性、及び厚み精度の確保のために少量の分岐状低密度ポリエチレン（Ｃ）の添加が必要である。しかし、（Ｃ）の添加量が多すぎると高速製膜時にフィルムの破断、破れ等の欠点が発生する。
【００１７】
本発明ではかかる点を考慮して、メタロセン触媒ポリエチレン（Ａ）２０〜９８重量％、チーグラー触媒ポリエチレン（Ｂ）１〜７９重量％、及び、分岐状低密度ポリエチレン（Ｃ）１〜８重量％の重量割合で含む混合樹脂を採用するものである。更に好ましくは、（Ａ）２０〜９５重量％、（Ｂ）３〜７９重量％、及び（Ｃ）１〜４重量％の重量割合で含む混合樹脂である。
【００１８】
本発明の多孔性フィルムに含まれる無機充填材としては、炭酸カルシウム、硫酸バリウム、硫酸カルシウム、炭酸バリウム、水酸化マグネシウム、水酸化アルミニウム、酸化亜鉛、酸化マグネシウム、酸化チタン、シリカ、タルク等が挙げられる。なかでも炭酸カルシウム及び硫酸バリウムが好ましく、最も好ましくは炭酸カルシウムである。これらの無機充填材は単独で用いても、二種類以上混合しても良い。上記ポリエチレン系混合樹脂と無機充填材との組成比は、樹脂１００重量部に対し、無機充填材部が５０〜５００重量部が好ましい。更に好ましくは、樹脂部１００重量部に対し、無機充填材を１００〜２５０重量部である。
【００１９】
これらの無機充填材は、ポリエチレンとの分散性を向上させ、更に樹脂との界面剥離を促し、外部からの水分の吸収を防ぐために表面処理が施されたものでもよい。表面処理剤としては、無機充填材の表面を被覆することによりその表面を疎水化できるものが好ましく、例として、ステアリン酸、ラウリル酸等の高級脂肪酸又はそれらの金属塩を挙げることができる。
【００２０】
本発明の多孔性フィルムは、上記の３種類のポリエチレン系混合樹脂、及び無機充填材を含むが、必要に応じて、延伸助剤として硬化ヒマシ油、脱水ヒマシ油、またはこれらの混合物を含んでもよい。硬化ヒマシ油の市販品としては、伊藤製油（株）製、商品名：カスターワックス等が挙げられる。また、脱水ヒマシ油の市販品としては、伊藤製油（株）製、商品名：ＤＣＯ等が挙げられる。延伸助剤の添加量が多すぎると、経時につれてフィルムより延伸助剤がブリードアウトする問題がある。かかる観点から、これらの添加量は混合樹脂１００重量部に対し、０．１〜１２重量部であることが好ましい。更に好ましくは１〜８重量部である。
【００２１】
本発明の多孔質フィルムには、本発明の目的を妨げない範囲で安定剤、酸化防止剤、着色剤、光安定剤、難燃剤、帯電防止剤、ブロッキング防止剤、消臭材、抗菌剤等の他の添加剤を添加しても良い。
【００２２】
次に、本発明の多孔性フィルムの製造方法について説明する。上記のポリエチレン系混合樹脂、無機充填材、必要に応じその他の添加剤を、ヘンシェルミキサー、スーパーミキサー、タンブラーミキサー等の混合機を用いて混合し、その後通常の一軸もしくは二軸スクリュー押出機によって混錬しペレット化する。次いで、このペレットを２００〜２８０℃、好ましくは２２０〜２６０℃においてＴダイ等が装着された押出成形機、円形ダイが装着されたインフレーション成形機等の公知の成形機を用いて、溶融、製膜する。原料をペレット化することなく、直接成形することもできる。
【００２３】
製膜したフィルムは、ロール法、テンター法などの公知の方法にて一軸方向または二軸方向にそれぞれ１．１〜４倍延伸を行い、ポリエチレン系樹脂と無機充填剤との界面剥離を起こさせることにより多孔性フィルムを製造する。延伸は、一段で行っても多段階に分けて行っても構わない。延伸倍率はフィルムの物性に大きな影響を及ぼす。１．１倍未満であると、樹脂と無機充填剤との界面剥離が十分でなく、満足する通気性が得られない。延伸倍率が４倍を超えると、フィルムの引っ張り破断伸びが低下する。延伸倍率は上記のような理由を考慮すると１．１〜４倍が好ましい。より好ましくは１．２〜２．７倍である。延伸温度は、室温〜樹脂の軟化点の温度範囲が好ましい。延伸後、必要に応じ得られたフィルムの形態を安定させるために熱固定処理を行っても良い。熱固定処理は、樹脂の軟化点以上、融点未満の温度範囲において０．１〜１００秒間行うことが好ましい。ここで、樹脂の軟化点とは、ＪＩＳ Ｋ−６７６０に規定される方法で測定した値である。
【００２４】
上記のようにして延伸した後、または、必要に応じて引き続き熱固定処理を行った後、冷却ロール等を用いてフィルムを室温近傍の温度まで冷却する。その後、高速で巻き取る。本発明においては、最大速度３００ｍ／分で巻き取ることが可能である。従来、フィルムの破れ等の発生を抑えるためにはせいぜい１６０ｍ／分程度が限度であった。本発明に係わる樹脂組成物を採用することにより、最大速度３００ｍ／分で巻き取ってもフィルムの破れ等の欠陥の発生を抑えることができる。
【００２５】
本発明により製造される多孔性フィルムの物性は、無機充填剤の充填割合、種類、粒径、硬化ヒマシ油、脱水ヒマシ油の配合割合、延伸条件（延伸方法、倍率、延伸温度等）によって自由に変えることができる。フィルムの厚みが１０〜１００μｍの範囲にあるときには、ＡＳＴＭ−Ｅ−９６（温度４０℃、相対湿度６０％、純水法の条件）に規定される方法で測定した透湿度が５００〜８０００ｇ／ｍ2・２４時間の範囲にある。また、本発明の方法で製造し得る多孔性フィルムの厚みには特に制限はないが、通常、５〜５００μｍ程度、好ましくは１０〜１００μｍ程度である。
【００２６】
本発明の多孔性フィルムの特徴的特性として、溶融張力が０．５〜４ｇ、溶融伸度が少なくとも８００％である点にある。溶融張力及び溶融伸度の測定方法は、後述する実施例で詳述する。本発明に係わる多孔性フィルムを細かく裁断した試料を１９０℃において特定の径のノズルから溶融押出し、引き取り速度２００ｍ／分でもフィラメント状溶融物が切れることがなく、この時の溶融張力が０．５〜４ｇ、溶融伸度が８００％以上である。本発明者らの知見によれば、該溶融張力が上記範囲より低すぎると、延伸ムラやドローレゾナンスが発生し、良好なフィルムを成形することができない。また、上記範囲より高すぎると高速製膜時にフィルムの破断もしくは破れ等の欠点が生じる。
【００２７】
本発明により製造された多孔性フィルムは、高速で巻き取った場合であっても、破れ等の欠陥が少ない。その上、通気性、透湿性、風合い等の多孔性フィルムとしての本来の特性は、従来もしくはそれ以上のレベルに維持されている。そのため、生産性の向上に役立つ。使い捨て紙オムツ、生理用ナプキン等の衛生材料のバックシート、手術着等の医療用材料、ジャンパー、雨具等の医療用材料、屋根防水材等の建築用材料、乾燥剤、防湿材、脱酸素材、使い捨てカイロ、鮮度保持包装、食品包装などの包装材、電池用セパレーターなどの資材として極めて好適に使用できる。
【００２８】
【実施例】
以下に本発明の実施例を詳細に述べる。なお、実施例に示したメルトインデックス（以下、ＭＩという）、溶融張力、透湿度、及び、高速製膜性は下記方法に測定した値である。
【００２９】
（１）ＭＩ（ｇ／１０分）
ＡＳＴＭ D−１２３８−５７Ｔ（Ｅ）に規定される方法により、温度１９０℃、荷重２１６０ｇの条件下で測定する。
【００３０】
（２）溶融張力（ｇ）、及び溶融伸度（％）
東洋精機製キャピログラフ１Ｃを用いる。直径９．５５ｍｍ、長さ３５０ｍｍのシリンダー内に細かく粉砕した多孔性フィルムを入れ、１９０℃で溶融させる。１５ｍｍ／分で溶融樹脂を押出し、シリンダー下部に取り付けたノズル径２．０９８ｍｍ、長さ８ｍｍのキャピラリーから出たフィラメントを室温において巻取る。巻取り速度２００ｍ／分の時の張力を測定し溶融張力（メルトテンション、単位：ｇ）とする。また、破断した場合にはその旨明記する。さらに、２００ｍ／分で巻き取ったフィラメントの径を測定し、キャピラリー径との断面積比をメルトエロンゲーション（溶融伸度、単位：％）とする。溶融伸度は下記数式により算出する。
溶融伸度（％）＝（キャピラリー径／フィラメント径）2。
【００３１】
（３）透湿度（ｇ／ｍ2・２４時間）
多孔性フィルム試料〔ＭＤ：１０ｃｍ、ＴＤ：１０ｃｍ〕を１０枚採取し、ＡＳＴＭ Ｅ−９６に規定される方法に基づき、温度４０℃、相対湿度６０％、純水法の条件で測定し、その平均値を算出する。測定時間は２４時間とする。
【００３２】
（４）高速製膜性の評価
Ｔダイより押し出し、キャスティングロールの周速度を１５０ｍ／分とし、巻取り速度３００ｍ／分、フィルム幅０．６ｍ、フィルム厚み２０μｍとした時、１時間に検出される欠点数を欠点検知機を用いて数える。欠点検知機は、興和紡績（株）製、焦点距離５０ｍｍ、Ｆ＝１．４のレンズを装着したＣＣＤカメラ（２０４８ｂｉｔ、２０ＭＨｚ）を５台用いて欠点を検知する。１時間あたりの欠点が１０個以下であれば高速製膜性が「優れる」、１１〜１００個であれば「劣る」、１０１個以上であれば「極めて劣る」と判定する。ここで、欠点とは長さ１ｍｍ以上の破れ等の欠陥を意味する。
【００３３】
実施例１
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）６７重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０１００Ｊ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝８．５ｇ／１０分）２９重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１４、密度０．９１９ｇ／ｃｍ3、ＭＩ＝５．１ｇ／１０分）４重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油（伊藤製油（株）製、商品名：カスターワックス）５重量部、及び、脱水ヒマシ油（伊藤製油（株）製、商品名：ＤＣＯ）２．５重量部をタンブラーミキサーですべてを混合し、その後、タンデム型押出し機を用いて、２３０℃において均一に混錬しペレット状に加工した。フィルム成形方法はＴダイが装着された押出成形機を用い、２４０℃において溶融押出しを行った。キャスティングロール速度を１５０ｍ／分とし、８０℃でフィルムを予熱した後、機械方向に２倍一軸延伸を行った。室温近傍の温度まで冷却した後、ライン速度３００ｍ／ｍｉｎで引き取り、ロール状の巻き物とし、幅０．６ｍ、厚さ２０μｍの多孔性フィルムを得た。得られた多孔性フィルムの溶融張力、透湿度、及び高速製膜性を上記方法で評価した。透湿度は３５００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００３４】
実施例２
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）９３重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）５重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１０２、密度０．９２１ｇ／ｃｍ3、ＭＩ＝０．３５ｇ／１０分）２重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油５重量部、及び、脱水ヒマシ油２重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は３１００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００３５】
実施例３
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）８６重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）１１重量部、岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソンＦ９６７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）３重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油４．５重量部、及び、脱水ヒマシ油２．５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は３１００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００３６】
実施例４
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）７２重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）２５重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソンＦ９６７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）３重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油４．５重量部、及び、脱水ヒマシ油２．５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は３２００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００３７】
実施例５
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）４８重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）４８重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソンＦ９６７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）４重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油４．５重量部、及び、脱水ヒマシ油２．５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は３３００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００３８】
実施例６
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）２５重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）７２重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソンＦ９６７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）３重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油４．５重量部、及び、脱水ヒマシ油２．５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２６００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００３９】
実施例７
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）４０重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）５６重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン２７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）４重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油３．８重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２７００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４０】
実施例８
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）２２重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）７７重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１０２、密度０．９２１ｇ／ｃｍ3、ＭＩ＝０．３５ｇ／１０分）１重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油２．５重量部、及び、脱水ヒマシ油４．５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２６００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４１】
実施例９
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ０５１０、密度：０．９０５ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）４０重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス１０３０Ｌ、密度：０．９１ｇ／ｃｍ3、ＭＩ＝３．６ｇ／１０分）５６重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１０２、密度０．９２１ｇ／ｃｍ3、ＭＩ＝０．３５ｇ／１０分）４重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油７重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２４００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４２】
比較例１
（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）７０重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）２０重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソンＦ９６７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）１０重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油５重量部、及び、脱水ヒマシ油２．５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２８００ｇ／ｍ2・２４時間であった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。溶融張力が高く、高速製膜時の欠点が多い。
【００４３】
比較例２
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）４０重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２０５Ｊ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２０ｇ／１０分）５７重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン２７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）３重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油２．５重量部、及び、脱水ヒマシ油５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。Ｔダイとキャスティングロールの間でドローレゾナンスが発生し、厚さ、透湿度において均一なフィルムを製膜することが出来なかった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４４】
比較例３
チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）９６重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソンＦ９６７、密度０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）４重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油５重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２７００ｇ／ｍ2・２４時間であった。フィルムの溶融張力は４．５ｇと高く，高速製膜時に欠陥が多く発生した。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４５】
比較例４
チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）９７重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１０２、密度０．９２１ｇ／ｃｍ3、ＭＩ＝０．３５ｇ／１０分）３重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油３重量部、脱水ヒマシ油３重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２６００ｇ／ｍ2・２４時間であった。フィルムの溶融張力の測定を行ったが、２００ｍ／分の引き取り速度で、破断したために溶融張力が測定できなかった。高速成膜時に欠陥が多数発生した。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４６】
比較例５
メタロセン触媒ポリエチレン（ダウ・ケミカル社製、商品名：アフィニティーＥＧ８１００、密度０．８７ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）２５重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）６８重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１４、密度０．９１９ｇ／ｃｍ3、ＭＩ＝５．１ｇ／１０分）７重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部を用いた以外はフィルムの製造及び評価方法は実施例１と同様とした。透湿度は１５００ｇ／ｍ2・２４時間であった。フィルムは柔らかく、風合いは良いが、透湿度が低い。フィルムの溶融張力は２００ｍ／分の引き取り速度で４．３ｇであり、高速製膜時に欠陥が多く発生した。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４７】
比較例６
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）９８重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１４、密度０．９１９ｇ／ｃｍ3、ＭＩ＝５．１ｇ／１０分）２重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、脱水ヒマシ油１２重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。高速製膜したところ、Ｔダイとキャスティングロールとの間でドローレゾナンスが発生し、厚さ、透湿度において均一なフィルムが製膜できなかった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４８】
比較例７
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）７重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分）８５重量部、分岐状低密度ポリエチレン（三井化学（株）製、商品名：ミラソン１０２、密度０．９２１ｇ／ｃｍ3、ＭＩ＝０．３５ｇ／１０分）８重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油８重量部、及び、脱水ヒマシ油３重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は２７００ｇ／ｍ2・２４時間であった。フィルムの溶融張力が４．８ｇと高く、高速時の欠点が多く発生した。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００４９】
比較例８
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分）４０重量部、チーグラー触媒ポリエチレン（三井化学（株）製、商品名：ウルトゼックス２０１００Ｊ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝８．５ｇ／１０分）６０重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油６重量部、及び、脱水ヒマシ油６重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。高速製膜したところＴダイとキャスティングロールとの間でドローレゾナンスが発生し、厚さ、透湿度において均一なフィルムが製膜できなかった。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００５０】
比較例９
メタロセン触媒ポリエチレン（三井化学（株）製、商品名：エボリューＳＰ０５１０、密度：０．９０５ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分）１００重量部、炭酸カルシウム（同和カルファイン（株）製、商品名：ＳＳＴ−４０−５）１８０重量部、硬化ヒマシ油９重量部を用いた以外は、フィルムの製造及び評価方法は実施例１と同様とした。透湿度は７５０ｇ／ｍ2・２４時間であった。フィルムの溶融張力が５．２ｇと高く、高速時の欠点が多く発生した。樹脂組成物の組成を〔表１〕、得られた結果を〔表２〕に示す。
【００５１】
【表１】
＜〔表１〕の符号の説明＞
〔表１〕に記載したＡ−１〜Ｃ−４の記号は下記樹脂を示す。
Ａ−１：三井化学（株）製、商品名：エボリューＳＰ１５４０、密度：０．９１５ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分。
Ａ−２：三井化学（株）製、商品名：エボリューＳＰ２０４０、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝４．０ｇ／１０分。
Ａ−３：三井化学（株）製、商品名：エボリューＳＰ０５１０、密度：０．９０５ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分。
Ａ−４：ダウ・ケミカル社製、商品名：アフィニティーＥＧ８１００、密度０．８７ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分
Ｂ−１：三井化学（株）製、商品名：ウルトゼックス２０２１Ｌ、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分。
Ｂ−２：三井化学（株）製、商品名：ウルトゼックス２０１００J、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝８．５ｇ／１０分。
Ｂ−３：三井化学（株）製、商品名：ウルトゼックス１０３０Ｌ、密度：０．９１ｇ／ｃｍ3、ＭＩ＝３．６ｇ／１０分。
Ｂ−４：三井化学（株）製、商品名：ウルトゼックス２０２０５J、密度：０．９２０ｇ／ｃｍ3、ＭＩ＝２０ｇ／１０分。
Ｃ−１：三井化学（株）製、商品名：ミラソン１０２、密度：０．９２１ｇ／ｃｍ3、ＭＩ＝０．３５ｇ／１０分。
Ｃ−２：三井化学（株）製、商品名：ミラソンＦ９６７、密度：０．９１８ｇ／ｃｍ3、ＭＩ＝１．０ｇ／１０分。
Ｃ−３：三井化学（株）製、商品名：ミラソン２７、密度：０．９１８ｇ／ｃｍ3、ＭＩ＝２．０ｇ／１０分。
Ｃ−４：三井化学（株）製、商品名：ミラソン１４、密度：０．９１９ｇ／ｃｍ3、ＭＩ＝５．１ｇ／１０分。
【００５３】
【表２】
【発明の効果】
本発明の多孔性フィルムは、最大速度３００ｍ／分で巻き取った場合であっても破れ等の欠陥を有することがなく、且つ、透湿度等の本来の特性が従来品と同レベルに維持された多孔性フィルムである。使い捨て紙オムツ、生理用ナプキン等の衛生材料のバックシート、手術着等の医療用材料、ジャンパー、雨具等の医療用材料、屋根防水材等の建築用材料、乾燥剤、防湿材、脱酸素材、使い捨てカイロ、鮮度保持包装、食品包装などの包装材、電池用セパレーターなどの資材として極めて好適に使用できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a porous film and a method for producing the same. Specifically, it is a porous film molded from a resin composition containing a specific mixed resin and a method for producing the same, and even when wound at a high speed after molding, a porous film having extremely few defects such as tearing and the like It relates to the manufacturing method.
[0002]
[Prior art]
Up to now, a porous film in which a void is generated by stretching a film in which an inorganic filler and various oils, wax, etc. are added to a polyolefin resin in at least a uniaxial direction and causing interfacial peeling between the inorganic filler and the polyolefin. Many manufacturing methods have been proposed (for example, JP-A-7-26076 and JP-A-9-25372). Since these porous films have a large number of minute voids inside, they do not allow liquid to pass through while having high moisture permeability. Taking advantage of this property, it has been widely used in various fields such as sanitary materials such as disposable diapers, building materials, reflective films, and battery separators.
[0003]
However, a problem when forming a film containing such a large amount of inorganic filler is that high-speed film formation is difficult. That is, since the inorganic filler is included, the drawdown property is deteriorated, and the film is broken or torn at the time of high-speed film formation. For these reasons, the conventional technique has a limit of a winding speed of about 160 m / min. Therefore, productivity was low. This tendency is remarkable when thin, for example, the basis weight is 20 g / m. 2 In the past, it has been difficult to form a porous film having uniform characteristics at high speed.
[0004]
[Problems to be solved by the invention]
In view of the above problems, an object of the present invention is a porous film that is free from defects such as tearing even when wound at high speed, and that maintains original properties such as moisture permeability equivalent to conventional products. And a method of manufacturing the same.
[0005]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that an ethylene-α-olefin copolymer (A) produced using a metallocene catalyst and an ethylene-α-olefin copolymer (B) produced using a Ziegler catalyst. And the present invention finds that the above-mentioned problems can be solved by using as a raw material a resin composition obtained by adding a predetermined amount of an inorganic filler to a mixed resin containing a specific amount of branched low-density polyethylene (C). It was.
[0006]
That is, the present invention has a melt index of 0.5 to 10 g / 10 min and a density of 0.905 to 0.945 g / cm. Three The ethylene-α-olefin copolymer (A) produced using a metallocene catalyst is 20 to 98% by weight, the melt index is 0.5 to 10 g / 10 min, and the density is 0.905 to 0.945 g / cm. Three 1 to 79% by weight of an ethylene-α-olefin copolymer (B) produced using a Ziegler catalyst, a melt index of 0.1 to 10 g / 10 min, and a density of 0.91 to 0.935 g / cm Three It is a porous film formed from a resin composition containing 50 to 500 parts by weight of an inorganic filler (D) with respect to 100 parts by weight of a resin containing 1 to 8% by weight of branched low density polyethylene (C). Moreover, the porous film has a melt tension of 0.5 to 4 g and a melt elongation of at least 800% at a temperature of 190 ° C., a take-up speed of 200 m / min.
[0007]
A preferable resin composition used in the present invention includes the resin composition containing 0.1 to 12 parts by weight of at least one compound selected from hardened castor oil and dehydrated castor oil with respect to 100 parts by weight of the mixed resin. It is done.
[0008]
In the porous film according to the present invention, the resin composition is kneaded and melted at 180 to 280 ° C. to form a film, and then at least uniaxially in the temperature range from room temperature to the softening point of the resin. The film is stretched twice, then cooled to a temperature close to room temperature, and then wound up at a maximum speed of 300 m / min. Preferably, it is produced by heat treatment for 0.1 to 100 seconds after stretching in a temperature range not lower than the softening temperature of the resin and lower than the melting point.
[0009]
The porous film of the present invention is characterized in that a mixed resin containing the above three resins (A), (B) and (C) at a specific weight ratio is used as a main raw material. Therefore, even after winding at a maximum speed of 300 m / min after film formation, there is no defect such as tearing, and the original properties such as moisture permeability are maintained at the same level or higher than conventional products. Porous film.
[0010]
In addition, the melt tension and the melt elongation in the present invention mean values measured by the methods described in Examples described later.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. The porous film of the present invention is a resin composition comprising a mixed resin containing three types of polyolefin resins (A), (B) and (C) at a specific weight ratio, and an inorganic filler, preferably a third component. The resin composition containing hydrogenated castor oil, dehydrated castor oil, or a mixture thereof is compounded with a biaxial or uniaxial kneader and then melt-molded into a film, and the resulting film is uniaxially or biaxially Manufactured by stretching at a predetermined magnification in the direction.
[0012]
The ethylene-α-olefin copolymer (A) polymerized using a metallocene catalyst used in the present invention includes an ethylene-α-olefin copolymer containing 0.5 to 10 mol% of α-olefin units. It is done. Among these, the melt index is 0.5 to 10 g / 10 min, and the density is 0.905 to 0.945 g / cm. Three Are preferred. More preferably, the melt index is 1 to 10 g / 10 min, and the density is 0.905 to 0.93 g / cm. Three belongs to. When the density exceeds the above range, the film becomes hard, which is not preferable. When the density is less than the above range, the air permeability is deteriorated and the possibility of blocking before and during molding increases. In addition, the relative intensity peak of the elution curve obtained by the temperature rising elution fractionation test is one in the elution temperature range of 70 to 90 ° C. and one in the range exceeding 90 ° C., and the ratio of the weight average molecular weight to the number average molecular weight is 1. An ethylene-α-olefin copolymer of 0.5 to 5.5 is preferred.
[0013]
Examples of the α-olefin unit of the ethylene-α-olefin copolymer include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and 1-nonene. . 1-hexene, 4-methyl-1-pentene, and 1-octene are more preferable. Commercially available products include Mitsui Chemicals, Inc., trade names: Evolue SP1540, Evolue SP2040, Evolue SP2520, and the like. Hereinafter, the copolymer (A) is referred to as metallocene-catalyzed polyethylene.
[0014]
Examples of the ethylene-α-olefin copolymer (B) polymerized using a Ziegler catalyst include ethylene-α-olefin copolymers containing 0.5 to 10 mol% of α-olefin units. Among these, melt index 0.5 to 10 g / 10 min, density 0.905 to 0.945 g / cm Three Are preferred. More preferably, the melt index is 1 to 10 g / 10 min, and the density is 0.91 to 0.93 g / cm. Three belongs to. When the density exceeds the above range, the film becomes hard and the tactile sensation is not preferable, and when the density is less than the above, the air permeability is deteriorated and it is not preferable as the air permeable film. Furthermore, the possibility of blocking during molding increases. Moreover, the ethylene-alpha-olefin copolymer whose ratio of the weight average molecular weight with respect to a number average molecular weight is 2.5-5.5 is preferable. Examples of commercially available products include Mitsui Chemicals Co., Ltd., trade names: ULTRAZEX 2021L, 20100J, 2520F, and the like. Hereinafter, the copolymer (B) is referred to as Ziegler-catalyzed polyethylene.
[0015]
The branched low density polyethylene (C) is a resin synthesized by a high pressure method, and may be an autoclave method or a tubular method. Among these, melt index 0.1 to 10 g / 10 min, density 0.91 to 0.935 g / cm Three Are preferred. More preferably, the melt index is 0.3 to 8 g / 10 min, and the density is 0.915 to 0.93 g / cm. Three belongs to. Further, the copolymer may contain 6% by weight or less of vinyl acetate units. Examples of commercially available products include Mitsui Chemicals, Inc., trade names: Mirason 14, F967, and 102. Hereinafter, the polyethylene (C) is referred to as branched low density polyethylene.
[0016]
The resin forming the porous film of the present invention is composed of a mixture of the metallocene catalyst polyethylene (A), the Ziegler catalyst polyethylene (B), and the branched low density polyethylene (C). In the present invention, it is particularly important that the metallocene catalyst polyethylene and the Ziegler catalyst polyethylene are mixed. Ziegler-catalyzed polyethylene (B) is very useful as a substrate for a porous film, but generally has a high speed film-forming property as compared with metallocene-catalyzed polyethylene (A). Therefore, metallocene-catalyzed polyethylene (A) is used, but this polyethylene is incompatible with the molding machine and causes problems in thickness unevenness and uniform stretchability. This invention improves the problem regarding this moldability by using Ziegler catalyst polyethylene (B) together. In addition, a small amount of branched low-density polyethylene (C) needs to be added to ensure uniform stretchability and thickness accuracy. However, if the amount of (C) added is too large, defects such as breakage and tearing of the film occur during high-speed film formation.
[0017]
In the present invention, in consideration of such points, the metallocene-catalyzed polyethylene (A) is 20 to 98% by weight, the Ziegler-catalyzed polyethylene (B) is 1 to 79% by weight, and the branched low-density polyethylene (C) is 1 to 8% by weight. A mixed resin containing by weight is employed. More preferably, it is a mixed resin containing (A) 20 to 95% by weight, (B) 3 to 79% by weight, and (C) 1 to 4% by weight.
[0018]
Examples of the inorganic filler contained in the porous film of the present invention include calcium carbonate, barium sulfate, calcium sulfate, barium carbonate, magnesium hydroxide, aluminum hydroxide, zinc oxide, magnesium oxide, titanium oxide, silica, and talc. It is done. Of these, calcium carbonate and barium sulfate are preferable, and calcium carbonate is most preferable. These inorganic fillers may be used alone or in combination of two or more. The composition ratio of the polyethylene-based mixed resin and the inorganic filler is preferably 50 to 500 parts by weight of the inorganic filler with respect to 100 parts by weight of the resin. More preferably, the inorganic filler is 100 to 250 parts by weight with respect to 100 parts by weight of the resin part.
[0019]
These inorganic fillers may be subjected to surface treatment in order to improve dispersibility with polyethylene, further promote interfacial peeling from the resin, and prevent moisture absorption from the outside. As the surface treatment agent, those capable of hydrophobizing the surface by coating the surface of the inorganic filler are preferable, and examples thereof include higher fatty acids such as stearic acid and lauric acid, and metal salts thereof.
[0020]
The porous film of the present invention contains the above-mentioned three types of polyethylene-based mixed resin and an inorganic filler, but if necessary, it may contain hardened castor oil, dehydrated castor oil, or a mixture thereof as a stretching aid. Good. As a commercial item of hydrogenated castor oil, Ito Oil Co., Ltd. product name: Custer wax etc. are mentioned. Moreover, as a commercial item of dehydrated castor oil, Ito Oil Co., Ltd. product name: DCO etc. are mentioned. When there is too much addition amount of extending | stretching adjuvant, there exists a problem that an extending | stretching adjuvant bleeds out from a film with time. From this viewpoint, it is preferable that these addition amounts are 0.1 to 12 parts by weight with respect to 100 parts by weight of the mixed resin. More preferably, it is 1-8 weight part.
[0021]
In the porous film of the present invention, a stabilizer, an antioxidant, a colorant, a light stabilizer, a flame retardant, an antistatic agent, an antiblocking agent, a deodorant, an antibacterial agent, etc., as long as the object of the present invention is not hindered. Other additives may be added.
[0022]
Next, the manufacturing method of the porous film of this invention is demonstrated. The above-mentioned polyethylene-based mixed resin, inorganic filler, and other additives as necessary are mixed using a mixer such as a Henschel mixer, super mixer, tumbler mixer, etc., and then mixed by a normal single or twin screw extruder. Refine and pelletize. Next, the pellets are melted and produced at 200 to 280 ° C., preferably 220 to 260 ° C., using a known molding machine such as an extrusion molding machine equipped with a T die or an inflation molding machine equipped with a circular die. Film. It is also possible to directly mold the raw material without pelletizing it.
[0023]
The formed film is stretched 1.1 to 4 times in a uniaxial direction or a biaxial direction by a known method such as a roll method or a tenter method to cause interfacial peeling between the polyethylene resin and the inorganic filler. Thus, a porous film is produced. Stretching may be performed in one step or in multiple steps. The draw ratio greatly affects the physical properties of the film. If it is less than 1.1 times, the interfacial peeling between the resin and the inorganic filler is not sufficient, and satisfactory air permeability cannot be obtained. When the draw ratio exceeds 4 times, the tensile elongation at break of the film decreases. Considering the reasons as described above, the draw ratio is preferably 1.1 to 4 times. More preferably, it is 1.2 to 2.7 times. The stretching temperature is preferably in the temperature range from room temperature to the softening point of the resin. After stretching, a heat setting treatment may be performed in order to stabilize the shape of the obtained film as necessary. The heat setting treatment is preferably performed for 0.1 to 100 seconds in a temperature range from the softening point of the resin to less than the melting point. Here, the softening point of the resin is a value measured by a method defined in JIS K-6760.
[0024]
After stretching as described above, or after performing heat setting treatment as necessary, the film is cooled to a temperature near room temperature using a cooling roll or the like. Then, it winds up at high speed. In the present invention, it is possible to wind up at a maximum speed of 300 m / min. Conventionally, the limit of about 160 m / min has been the limit in order to suppress the occurrence of film breakage and the like. By employing the resin composition according to the present invention, it is possible to suppress the occurrence of defects such as tearing of the film even when the film is wound at a maximum speed of 300 m / min.
[0025]
The physical properties of the porous film produced according to the present invention can be freely selected depending on the filling ratio, type, particle size, blended ratio of hardened castor oil and dehydrated castor oil, and stretching conditions (stretching method, magnification, stretching temperature, etc.). Can be changed to When the thickness of the film is in the range of 10 to 100 μm, the moisture permeability measured by the method prescribed in ASTM-E-96 (temperature 40 ° C., relative humidity 60%, condition of pure water method) is 500 to 8000 g / m. 2 -It is in the range of 24 hours. Moreover, there is no restriction | limiting in particular in the thickness of the porous film which can be manufactured with the method of this invention, Usually, about 5-500 micrometers, Preferably it is about 10-100 micrometers.
[0026]
The characteristic properties of the porous film of the present invention are that the melt tension is 0.5 to 4 g and the melt elongation is at least 800%. The measuring method of melt tension and melt elongation will be described in detail in Examples described later. A sample obtained by finely cutting the porous film according to the present invention was melt-extruded from a nozzle having a specific diameter at 190 ° C., and the filament-shaped melt was not cut even at a take-off speed of 200 m / min. ˜4 g, melt elongation is 800% or more. According to the knowledge of the present inventors, when the melt tension is too lower than the above range, stretching unevenness and draw resonance occur, and a good film cannot be formed. On the other hand, if it is higher than the above range, defects such as breakage or tearing of the film occur at the time of high-speed film formation.
[0027]
The porous film produced according to the present invention has few defects such as tearing even when wound at high speed. In addition, the original characteristics of the porous film such as air permeability, moisture permeability, and texture are maintained at a conventional level or higher. Therefore, it helps to improve productivity. Sanitary materials such as disposable paper diapers, sanitary napkins, medical materials such as surgical clothes, medical materials such as jumpers and rain gear, building materials such as roof waterproof materials, desiccants, moisture-proof materials, and deoxidizing materials It can be used very suitably as a material for packaging materials such as disposable body warmers, freshness-keeping packaging and food packaging, and battery separators.
[0028]
【Example】
Examples of the present invention will be described in detail below. Note that the melt index (hereinafter referred to as MI), melt tension, moisture permeability, and high-speed film-forming properties shown in the examples are values measured by the following methods.
[0029]
(1) MI (g / 10 min)
It is measured under the conditions of a temperature of 190 ° C. and a load of 2160 g by the method prescribed in ASTM D-1238-57T (E).
[0030]
(2) Melt tension (g) and melt elongation (%)
A Toyo Seiki Capillograph 1C is used. A finely pulverized porous film is placed in a cylinder having a diameter of 9.55 mm and a length of 350 mm, and melted at 190 ° C. The molten resin is extruded at 15 mm / min, and the filament coming out from a capillary having a nozzle diameter of 2.098 mm and a length of 8 mm attached to the lower part of the cylinder is wound up at room temperature. The tension at a winding speed of 200 m / min is measured to obtain the melt tension (melt tension, unit: g). If it breaks, specify that fact. Furthermore, the diameter of the filament wound up at 200 m / min is measured, and the cross-sectional area ratio with the capillary diameter is defined as melt elongation (melt elongation, unit:%). The melt elongation is calculated by the following formula.
Melt elongation (%) = (capillary diameter / filament diameter) 2 .
[0031]
(3) Moisture permeability (g / m 2 ・ 24 hours)
Ten porous film samples [MD: 10 cm, TD: 10 cm] were collected and measured under the conditions of a temperature of 40 ° C., a relative humidity of 60%, and a pure water method based on the method specified in ASTM E-96. The average value is calculated. The measurement time is 24 hours.
[0032]
(4) Evaluation of high-speed film-forming property
Use a defect detector to detect the number of defects detected in one hour when extruded from a T-die, the peripheral speed of the casting roll is 150 m / min, the winding speed is 300 m / min, the film width is 0.6 m, and the film thickness is 20 μm. Count. The defect detector uses five CCD cameras (2048 bits, 20 MHz) equipped with a lens with a focal length of 50 mm and F = 1.4, manufactured by Kowa Boseki Co., Ltd., to detect defects. If the number of defects per hour is 10 or less, the high-speed film-forming property is determined to be “excellent”, 11 to 100 is “inferior”, and 101 or more is determined to be “very inferior”. Here, the defect means a defect such as a tear having a length of 1 mm or more.
[0033]
Example 1
Metallocene catalyst polyethylene (manufactured by Mitsui Chemicals, trade name: Evolue SP2040, density: 0.920 g / cm Three MI = 4.0 g / 10 min) 67 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 20100J, density: 0.920 g / cm) Three , MI = 8.5 g / 10 min) 29 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 14, density 0.919 g / cm) Three , MI = 5.1 g / 10 min) 4 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hydrogenated castor oil (manufactured by Ito Oil Co., Ltd., product) Name: Custer wax) 5 parts by weight and dehydrated castor oil (Ito Oil Co., Ltd., trade name: DCO) 2.5 parts by weight were all mixed with a tumbler mixer, and then using a tandem extruder. The mixture was uniformly kneaded at 230 ° C. and processed into pellets. As the film forming method, melt extrusion was carried out at 240 ° C. using an extruder equipped with a T die. The film was preheated at 80 ° C. at a casting roll speed of 150 m / min, and then uniaxially stretched twice in the machine direction. After cooling to a temperature in the vicinity of room temperature, the film was taken up at a line speed of 300 m / min to obtain a roll-shaped roll, and a porous film having a width of 0.6 m and a thickness of 20 μm was obtained. The obtained porous film was evaluated for melt tension, moisture permeability, and high-speed film-forming property by the above methods. Moisture permeability is 3500g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0034]
Example 2
Metallocene catalyst polyethylene (manufactured by Mitsui Chemicals, trade name: Evolue SP2040, density: 0.920 g / cm Three , MI = 4.0 g / 10 min) 93 parts by weight, Ziegler catalyst polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min) 5 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 102, density 0.921 g / cm) Three , MI = 0.35 g / 10 min) 2 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 5 parts by weight, and dehydrated castor oil The production and evaluation method of the film was the same as in Example 1 except that 2 parts by weight were used. Moisture permeability is 3100g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0035]
Example 3
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three , MI = 4.0 g / 10 min) 86 parts by weight, Ziegler catalyst polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min) 11 parts by weight, multi-layer low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density 0.918 g / cm) Three MI = 1.0 g / 10 min) 3 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 4.5 parts by weight, and dehydration The production and evaluation method of the film was the same as in Example 1 except that 2.5 parts by weight of castor oil was used. Moisture permeability is 3100g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0036]
Example 4
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three , MI = 4.0 g / 10 min) 72 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min), 25 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density: 0.918 g / cm) Three MI = 1.0 g / 10 min) 3 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 4.5 parts by weight, and dehydration The production and evaluation method of the film was the same as in Example 1 except that 2.5 parts by weight of castor oil was used. Moisture permeability is 3200g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0037]
Example 5
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three , MI = 4.0 g / 10 min) 48 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min) 48 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density 0.918 g / cm) Three , MI = 1.0 g / 10 min) 4 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 4.5 parts by weight, and dehydration The production and evaluation method of the film was the same as in Example 1 except that 2.5 parts by weight of castor oil was used. Moisture permeability is 3300g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0038]
Example 6
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three , MI = 4.0 g / 10 min), 25 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min) 72 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density 0.918 g / cm) Three MI = 1.0 g / 10 min) 3 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 4.5 parts by weight, and dehydration The production and evaluation method of the film was the same as in Example 1 except that 2.5 parts by weight of castor oil was used. Moisture permeability is 2600g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0039]
Example 7
Metallocene catalyst polyethylene (manufactured by Mitsui Chemicals, trade name: Evolue SP2040, density: 0.920 g / cm Three , MI = 4.0 g / 10 min) 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min), 56 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 27, density: 0.918 g / cm) Three , MI = 2.0 g / 10 min) 4 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, and 3.8 parts by weight of hardened castor oil The film production and evaluation method were the same as in Example 1. Moisture permeability is 2700 g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0040]
Example 8
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three , MI = 4.0 g / 10 min) 22 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min) 77 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 102, density 0.921 g / cm) Three , MI = 0.35 g / 10 min) 1 part by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 2.5 parts by weight, and dehydration The production and evaluation method of the film was the same as in Example 1 except that 4.5 parts by weight of castor oil was used. Moisture permeability is 2600g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0041]
Example 9
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP0510, density: 0.905 g / cm Three , MI = 1.0 g / 10 min) 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 1030L, density: 0.91 g / cm) Three , MI = 3.6 g / 10 min) 56 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 102, density 0.921 g / cm Three , MI = 0.35 g / 10 min) 4 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 7 parts by weight, The production and evaluation method of the film was the same as in Example 1. Moisture permeability is 2400g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0042]
Comparative Example 1
(Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three , MI = 4.0 g / 10 min) 70 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm) Three , MI = 2.0 g / 10 min) 20 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason F967, density 0.918 g / cm) Three MI = 1.0 g / 10 min) 10 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hydrogenated castor oil 5 parts by weight, and dehydrated castor oil The production and evaluation method of the film was the same as in Example 1 except that 2.5 parts by weight was used. Moisture permeability is 2800g / m 2 ・ It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2]. The melt tension is high and there are many drawbacks during high-speed film formation.
[0043]
Comparative Example 2
Metallocene catalyst polyethylene (manufactured by Mitsui Chemicals, trade name: Evolue SP2040, density: 0.920 g / cm Three , MI = 4.0 g / 10 min) 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 20205J, density: 0.920 g / cm) Three MI = 20 g / 10 min) 57 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 27, density 0.918 g / cm Three MI = 2.0 g / 10 min) 3 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 2.5 parts by weight, and dehydration The production and evaluation method of the film was the same as in Example 1 except that 5 parts by weight of castor oil was used. Draw resonance occurred between the T die and the casting roll, and it was impossible to form a uniform film in terms of thickness and moisture permeability. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0044]
Comparative Example 3
Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm Three , MI = 2.0 g / 10 min) 96 parts by weight, branched low density polyethylene (Mitsui Chemicals, Inc., trade name: Mirason F967, density 0.918 g / cm) Three , MI = 1.0 g / 10 min) 4 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hydrogenated castor oil 5 parts by weight, The production and evaluation method of the film was the same as in Example 1. Moisture permeability is 2700 g / m 2 ・ It was 24 hours. The melt tension of the film was as high as 4.5 g, and many defects occurred during high-speed film formation. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0045]
Comparative Example 4
Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm Three MI = 2.0 g / 10 min) 97 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 102, density 0.921 g / cm) Three , MI = 0.35 g / 10 min) 3 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 3 parts by weight, dehydrated castor oil 3 parts by weight The production and evaluation methods of the film were the same as in Example 1 except that the parts were used. Moisture permeability is 2600g / m 2 ・ It was 24 hours. The melt tension of the film was measured, but the melt tension could not be measured because the film was broken at a take-up speed of 200 m / min. Many defects occurred during high-speed film formation. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0046]
Comparative Example 5
Metallocene-catalyzed polyethylene (manufactured by Dow Chemical Company, trade name: Affinity EG8100, density 0.87 g / cm Three , MI = 1.0 g / 10 min) 25 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm) Three MI = 2.0 g / 10 min) 68 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 14, density 0.919 g / cm) Three , MI = 5.1 g / 10 min) 7 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) Except for using 180 parts by weight, film production and evaluation methods were carried out. Same as Example 1. Moisture permeability is 1500g / m 2 ・ It was 24 hours. The film is soft and the texture is good, but the moisture permeability is low. The melt tension of the film was 4.3 g at a take-up speed of 200 m / min, and many defects occurred during high-speed film formation. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0047]
Comparative Example 6
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP1540, density: 0.915 g / cm Three MI = 4.0 g / 10 min) 98 parts by weight, branched low-density polyethylene (Mitsui Chemicals, Inc., trade name: Mirason 14, density 0.919 g / cm) Three MI = 5.1 g / 10 min) 2 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, dehydrated castor oil 12 parts by weight, The production and evaluation method of the film was the same as in Example 1. When the film was formed at high speed, draw resonance occurred between the T die and the casting roll, and a film having a uniform thickness and moisture permeability could not be formed. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0048]
Comparative Example 7
Metallocene catalyst polyethylene (manufactured by Mitsui Chemicals, trade name: Evolue SP2040, density: 0.920 g / cm Three , MI = 4.0 g / 10 min) 7 parts by weight, Ziegler catalyst polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm) Three MI = 2.0 g / 10 min) 85 parts by weight, branched low density polyethylene (Mitsui Chemicals, trade name: Mirason 102, density 0.921 g / cm) Three , MI = 0.35 g / 10 min) 8 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 8 parts by weight, and dehydrated castor oil The production and evaluation method of the film was the same as in Example 1 except that 3 parts by weight was used. Moisture permeability is 2700 g / m 2 ・ It was 24 hours. The melt tension of the film was as high as 4.8 g, and many defects at high speed occurred. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0049]
Comparative Example 8
Metallocene catalyst polyethylene (manufactured by Mitsui Chemicals, trade name: Evolue SP2040, density: 0.920 g / cm Three , MI = 4.0 g / 10 min) 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 20100J, density: 0.920 g / cm) Three MI = 8.5 g / 10 min) 60 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hardened castor oil 6 parts by weight, and dehydrated castor oil The production and evaluation method of the film was the same as in Example 1 except that 6 parts by weight was used. When high-speed film formation was performed, draw resonance was generated between the T die and the casting roll, and a uniform film could not be formed in terms of thickness and moisture permeability. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0050]
Comparative Example 9
Metallocene-catalyzed polyethylene (Mitsui Chemicals, trade name: Evolue SP0510, density: 0.905 g / cm Three , MI = 1.0 g / 10 min) 100 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5) 180 parts by weight, hydrogenated castor oil 9 parts by weight, The production and evaluation method of the film was the same as in Example 1. Moisture permeability is 750g / m 2 ・ It was 24 hours. The melt tension of the film was as high as 5.2 g, and many defects at high speed occurred. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].
[0051]
[Table 1]
<Description of symbols in [Table 1]>
The symbols A-1 to C-4 described in [Table 1] represent the following resins.
A-1: manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP1540, density: 0.915 g / cm Three MI = 4.0 g / 10 min.
A-2: manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP2040, density: 0.920 g / cm Three MI = 4.0 g / 10 min.
A-3: manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP0510, density: 0.905 g / cm Three MI = 1.0 g / 10 min.
A-4: manufactured by Dow Chemical Co., Ltd., trade name: affinity EG8100, density 0.87 g / cm Three MI = 1.0g / 10min
B-1: manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 2021L, density: 0.920 g / cm Three MI = 2.0 g / 10 min.
B-2: manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 20100J, density: 0.920 g / cm Three MI = 8.5 g / 10 min.
B-3: manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 1030L, density: 0.91 g / cm Three MI = 3.6 g / 10 min.
B-4: manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX 20205J, density: 0.920 g / cm Three MI = 20 g / 10 min.
C-1: Mitsui Chemicals Co., Ltd., trade name: Mirason 102, density: 0.921 g / cm Three , MI = 0.35 g / 10 min.
C-2: manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density: 0.918 g / cm Three MI = 1.0 g / 10 min.
C-3: manufactured by Mitsui Chemicals, trade name: Mirason 27, density: 0.918 g / cm Three MI = 2.0 g / 10 min.
C-4: manufactured by Mitsui Chemicals, trade name: Mirason 14, density: 0.919 g / cm Three MI = 5.1 g / 10 min.
[0053]
[Table 2]
【The invention's effect】
The porous film of the present invention has no defects such as tearing even when wound at a maximum speed of 300 m / min, and the original characteristics such as moisture permeability are maintained at the same level as conventional products. Porous film. Sanitary materials such as disposable paper diapers, sanitary napkins, medical materials such as surgical clothes, medical materials such as jumpers and rain gear, building materials such as roof waterproof materials, desiccants, moisture-proof materials, and deoxidizing materials It can be used very suitably as a material for packaging materials such as disposable body warmers, freshness-keeping packaging and food packaging, and battery separators.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004099666A (en) * | 2002-09-05 | 2004-04-02 | Kao Corp | Method for producing moisture-permeable sheet |
| JP2006514124A (en) * | 2003-06-19 | 2006-04-27 | ボレアリス テクノロジー オイ | Breathable film |
| US7932196B2 (en) | 2003-08-22 | 2011-04-26 | Kimberly-Clark Worldwide, Inc. | Microporous stretch thinned film/nonwoven laminates and limited use or disposable product applications |
| JP2005126694A (en) * | 2003-10-02 | 2005-05-19 | Tokuyama Corp | Ethylenic polymer composition for high-speed drawn film-forming and method for producing porous film |
| JP4651609B2 (en) * | 2006-12-11 | 2011-03-16 | 花王株式会社 | Method for producing moisture permeable sheet |
| JP5270867B2 (en) * | 2006-12-28 | 2013-08-21 | 日本ポリエチレン株式会社 | Breathable film |
| WO2015186808A1 (en) * | 2014-06-04 | 2015-12-10 | 三菱樹脂株式会社 | Moisture permeable film |
| WO2022059091A1 (en) * | 2020-09-16 | 2022-03-24 | 日本サニパック株式会社 | Polyethylene-based resin composition, polyethylene-based resin packaging material, and method for producing same |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0925372A (en) * | 1995-07-12 | 1997-01-28 | Maruzen Petrochem Co Ltd | Moisture-permeable film |
| JPH09176400A (en) * | 1995-12-27 | 1997-07-08 | Nippon Poriorefuin Kk | Filler-containing ethylene/alpha-olefin copolymer composition and molding using the same |
| JPH09221560A (en) * | 1995-12-13 | 1997-08-26 | Mitsui Toatsu Chem Inc | Porous film and its production |
| JPH09255824A (en) * | 1996-03-27 | 1997-09-30 | Nippon Petrochem Co Ltd | Filler-containing ethylene-based polymer composition |
| JP2000001557A (en) * | 1998-06-12 | 2000-01-07 | Kao Corp | Moisture-permeable film and absorbent article |
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2001
- 2001-01-10 JP JP2001002401A patent/JP4540858B2/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0925372A (en) * | 1995-07-12 | 1997-01-28 | Maruzen Petrochem Co Ltd | Moisture-permeable film |
| JPH09221560A (en) * | 1995-12-13 | 1997-08-26 | Mitsui Toatsu Chem Inc | Porous film and its production |
| JPH09176400A (en) * | 1995-12-27 | 1997-07-08 | Nippon Poriorefuin Kk | Filler-containing ethylene/alpha-olefin copolymer composition and molding using the same |
| JPH09255824A (en) * | 1996-03-27 | 1997-09-30 | Nippon Petrochem Co Ltd | Filler-containing ethylene-based polymer composition |
| JP2000001557A (en) * | 1998-06-12 | 2000-01-07 | Kao Corp | Moisture-permeable film and absorbent article |
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| Publication number | Publication date |
|---|---|
| JP2001261868A (en) | 2001-09-26 |
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