JP4433567B2 - Latent crimpable conjugate fiber and nonwoven fabric using the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、熱処理により捲縮が発現する潜在捲縮性を有するポリオレフィン系複合繊維及びそれを用いた不織布に関するものである。
【０００２】
【従来の技術】
従来から、嵩高な不織布を得る手法の一つに、クリンパー等の捲縮付与手段を用いてジグザグ型の機械捲縮を付与した繊維や、繊維の複合形態を並列型または偏心鞘芯型とし、延伸等の手段で繊維内部に歪みを生じさせることにより螺旋状立体捲縮を付与した繊維を用いる方法があった。
【０００３】
例えば、特開平2-191720号公報には、鞘成分として主にエチレン−プロピレンランダム共重合体を配し、芯成分に結晶性ポリプロピレンを配した鞘芯型複合繊維が提案されている。これは、この繊維からなるウェブに熱処理を施すことにより、鞘成分として用いているエチレン−プロピレンランダム共重合体の熱収縮特性を利用し、不織布加工時に潜在捲縮を発現させ、嵩高な不織布を製造するものである。しかしながら、鞘成分に配したエチレン−プロピレンランダム共重合体の金属摩擦抵抗は、一般に繊維に用いる他の樹脂、例えば高密度ポリエチレンなどに比べて非常に大きいため、カード機から排出されにくく、均一なウェブを得ることが難しいという問題があり、得られた不織布においても、鞘成分の樹脂の特性に起因する特有のぬめり感、べたつき感があった。また原綿は一般に開繊機により開繊され、送風管によりカード機まで輸送されるが、金属摩擦抵抗の大きい繊維は送風管の壁面に綿が付着する輸送性不良の問題があった。さらに、カード工程を必要としないスパンボンド法によって、これらの樹脂を組み合わせて複合長繊維を紡糸した場合においても、繊維表面を覆ったエチレン−プロピレンランダム共重合体の高い繊維間摩擦により繊維の開繊性が悪く、コンベア上に集積されたウェブが十分に均一にならないという問題があった。以上のように現在まで、潜在捲縮性を有する繊維を用いた嵩高で良好な地合の不織布は得られていないのが実状であるが、近年、紙オムツや生理用品市場競争の激化に伴って、さらに風合いがよく、嵩高な不織布を要望する声が高まっている。
【０００４】
【発明が解決しようとする課題】
本発明は、上記問題点を解決し、嵩高で、風合いが良好な不織布及びその原料となる潜在捲縮性複合繊維を提供することを課題とする。
【０００５】
【課題を解決するための手段】
本発明者らは、上記目的を達成すべく鋭意検討した結果、以下の手段を見いだし、本発明の完成に至った。本発明は以下の構成からなる。
（１）融点Ｔｍ（℃）が１２０≦Ｔｍ≦１４７で、９０〜９８重量％のプロピレンおよび２〜１０重量％のプロピレン以外のα−オレフィンからなるプロピレン共重合体を第１成分とし、ポリエチレンを第２成分とする複合繊維であって、第１成分と第２成分の複合の形態が第２成分を鞘側に配置した偏心鞘芯型であり、かつ繊維横断面における第１成分と第２成分の面積比は６５／３５〜３５／６５であることを特徴とし、該複合繊維をウェブに加工した状態で下記の方法によって測定される繊維機械方向（ＭＤ）の熱収縮率が５０％以上である、潜在捲縮性複合繊維。
２５×２５ｃｍ、目付約２００ｇ／ｍ ２ のウェブを、クラフト紙にのせて１４５℃に維持した対流型熱風乾燥機に入れ、５分間加熱処理する。熱処理前後のウェブのＭＤの長さから、熱収縮率を次式により算出する。
熱収縮率（％）＝（１−ａ／２５）×１００
なお、式中のａは熱処理したウェブのＭＤの長さである。
（２） 第１成分が９０〜９６重量％のプロピレンおよび４〜１０重量％のプロピレン以外のα−オレフィンからなるプロピレン共重合体であることを特徴とする前記（１）項に記載の潜在捲縮性複合繊維。
（３） 第１成分が、９０〜９６重量％のプロピレン、３〜７重量％のエチレンおよび１〜５重量％のブテン−１からなるエチレン−プロピレン−ブテン−１三元共重合体である前記（１）〜（２）項のいずれかに記載の潜在捲縮性複合繊維。
（４）第２成分が、高密度ポリエチレン、直鎖状低密度ポリエチレン、低密度ポリエチレンから選ばれた少なくとも一種からなることを特徴とする前記（１）〜（３）項のいずれかに記載の潜在捲縮性複合繊維。
（５）第２成分が、第１成分の融点Ｔｍ（℃）よりも低い融点を有するポリエチレンであることを特徴とする前記（１）〜（４）項のいずれかに記載の潜在捲縮性複合繊維。
（６）潜在捲縮性複合繊維が長繊維であることを特徴とする前記（１）〜（５）項のいずれかに記載の潜在捲縮性複合繊維。
（７）融点Ｔｍ（℃）が１２０≦Ｔｍ≦１４７で、９０〜９８重量％のプロピレンおよび２〜１０重量％のプロピレン以外のα−オレフィンからなるプロピレン共重合体を第１成分とし、ポリエチレンを第２成分とする複合繊維であって、第１成分と第２成分の複合の形態が第２成分を鞘側に配置した偏心鞘芯型であり、かつ繊維横断面における第１成分と第２成分の面積比は６５／３５〜３５／６５であることを特徴とする潜在捲縮性複合繊維を用いて得られ、下記の方法によって測定される繊維機械方向（ＭＤ）の熱収縮率が５０％以上である、ウェブ。
２５×２５ｃｍ、目付約２００ｇ／ｍ２のウェブを、クラフト紙にのせて１４５℃に維持した対流型熱風乾燥機に入れ、５分間加熱処理する。熱処理前後のウェブのＭＤの長さから、熱収縮率を次式により算出する。
熱収縮率（％）＝（１−ａ／２５）×１００
なお、式中のａは熱処理したウェブのＭＤの長さである。
（８）前記（１）〜（６）項のいずれかに記載の潜在捲縮性複合繊維または前記（７）項に記載のウェブを用いた不織布。
（９）前記（１）〜（６）項のいずれかに記載の潜在捲縮性複合繊維または前記（７）項に記載のウェブを用いて、第１成分の融点以下、第２成分の融点以上の温度範囲で熱処理して、不織布化と収縮処理を同時に施すか、または、繊維同士が熱接着しない程度の低い温度（両成分の融点未満）による熱処理によって捲縮を発現させて繊維を交絡させることのみで不織布を製造することを特徴とする、不織布の製造方法。
【０００６】
【発明の実施の形態】
以下に、本発明の実施の具体的態様を示す。
本発明の潜在捲縮性複合繊維を構成する第１成分としては、加工性の点から、比較的低温で熱収縮を起こし、なおかつ繊維形成性を有する、融点Ｔｍ（℃）が１２０≦Ｔｍ≦１４７の範囲にあるプロピレン共重合体が挙げられる。この様なプロピレン共重合体はプロピレンを主として、これと他のα−オレフィンとを共重合することにより得ることができる。このようなα−オレフィンとしては、例えばエチレン、ブテン−１、ペンテン−１、ヘキセン−１、ヘプテン−１、オクテン−１、４−メチル−ペンテン−１などを例示でき、またこれらのα−オレフィンのうち２種以上を併用することもできる。プロピレン共重合体の具体例としてはエチレン−プロピレン二元共重合体、プロピレン−ブテン−１二元共重合体、エチレン−プロピレン−ブテン−１三元共重合体、プロピレン−ヘキセン−１二元共重合体、プロピレン−オクテン−１二元共重合体等、およびこれらの混合物を例示することができる。これらの共重合体は通常、ランダム共重合体であるがブロック共重合体であってもよい。
【０００７】
本発明の潜在捲縮性繊維の第１成分として使用できる、融点Ｔｍ（℃）が前述した範囲内に含まれるプロピレン共重合体の中でも、９０〜９８重量％のプロピレン、１〜７重量％のエチレン、１〜５重量％のブテン−１からなるエチレン−プロピレン−ブテン−１三元共重合体や、９０〜９８重量％のプロピレン、２〜１０重量％のエチレンからなるエチレン−プロピレン二元共重合体がコスト面から好ましく、熱によって収縮処理する際の低温加工性、収縮力の観点からは、第１成分として、９０〜９６重量％のプロピレン、４〜１０重量％のエチレンからなるエチレン−プロピレン二元共重合体や、９０〜９６重量％のプロピレン、３〜７重量％のエチレン、１〜５重量％のブテン−１からなるエチレン−プロピレン−ブテン−１三元共重合体を用いることがより好ましい。なお、これら樹脂において融点Ｔｍ（℃）が１２０℃未満であるものは、ゴム弾性を示すために、得られた繊維のカード加工性に悪影響を与える。また、融点Ｔｍ（℃）が１４７℃を超えるプロピレン共重合体を第１成分として使用した場合には、得られた繊維の収縮性は通常のポリプロピレン単成分繊維、ポリエチレン／ポリプロピレン複合繊維程度まで低下してしまう。したがって、組成が前述した範囲内にあるプロピレン共重合体を第１成分として使用することで、カード加工性、熱収縮性を両立した潜在捲縮性繊維を得ることができる。なお、本発明の繊維の熱収縮性を極端に低下させない程度、または熱収縮性を軽度に抑制する程度であれば、必要に応じて第１成分に二酸化チタン，炭酸カルシウムおよび水酸化マグネシウム等の無機物や、難燃剤、顔料及びその他のポリマーを添加しても差し支えない。
【０００８】
本発明の潜在捲縮性繊維の第２成分として使用できるポリエチレンとは、以下に述べるような融点、密度の区分で大きく分類される高密度ポリエチレン、直鎖状低密度ポリエチレン、低密度ポリエチレンを挙げることができる。
【０００９】
本発明でいう高密度ポリエチレンとは、公知のチーグラーナッタ触媒を用いて低圧法で重合された、エチレン単独の重合体もしくは少量の、通常は最大２重量％までの割合のＣ３〜Ｃ１２のアルケンをコモノマーとして含有するエチレン系共重合体であり、一般に０．９４１〜０．９６５ｇ／ｃｍ3の密度、および１２７℃以上の融点を有するポリエチレンである。
【００１０】
本発明でいう直鎖状低密度ポリエチレンとは、公知のチーグラーナッタ触媒を用いて重合された、実質的な長分岐鎖を持たない、通常１５重量％以下の割合のＣ３〜Ｃ１２のアルケンをコモノマーとして含有するエチレン系共重合体を指しており、一般に０．９２５〜０．９４０ｇ／ｃｍ3の密度、および１２７℃未満の融点を有するポリエチレンである。
【００１１】
本発明でいう低密度ポリエチレンとは、高圧法で重合された、一般に密度０．９１０〜０．９４０ｇ／ｃｍ3、および融点１２０℃以下の、分岐鎖が多く結晶性の低いポリエチレンである。
【００１２】
さらに、メタロセン触媒を用いて重合されたポリエチレン系樹脂は、上記の樹脂よりもさらに低い融点を有することから繊維同士を熱接着する場合の低温加工性の面から有利であると同時に、狭い分子量分布を有することから紡糸安定性に大きく寄与するため、本発明の第２成分として好適に使用できる。なお、本発明の潜在捲縮性繊維を製造する際には低温加工性や工程安定性を付与するために、これらのポリエチレンから選ばれる数種の樹脂を混合したり、または本発明の目的を妨げない程度であれば、必要に応じて第２成分に、二酸化チタン，炭酸カルシウムおよび水酸化マグネシウム等の無機物や、難燃剤、顔料及びその他のポリマーを添加してもよい。
【００１３】
本発明の潜在捲縮性繊維においては、第２成分に第１成分の融点Ｔｍ（℃）よりも融点が低いポリエチレンを用いることで、繊維に熱接着性を付与することもできる。つまり必要に応じて第１成分と第２成分に融点差を持たせるように樹脂を適宜選択すれば、高圧水流によって繊維同士を交絡させたウェブにエンボス加工、ヒートピン加工等の手法により繊維同士を熱接着し、不織布の風合い、嵩高性を損なわない範囲で不織布の強度を向上させたり、伸縮性を調整することもできる。特に第１成分の融点以下、第２成分の融点以上の温度範囲で熱処理した場合には不織布化と収縮処理を同時に施すことができるため、不織布製造工程を簡略化することができる。なおこの時、第２成分の融点は第１成分の融点Ｔｍ（℃）よりも５℃以上、より好ましくは１０℃以上低いことが望ましい。また、不織布の用途によっては繊維同士が熱接着しない程度の低い温度（両成分の融点未満）による熱処理によって捲縮を発現させ、繊維を交絡させることのみで不織布を製造することもできる。両成分の融点未満の温度で熱収縮による潜在捲縮を発現させるのみで、実用に耐えうる不織布が得られるのであれば、必ずしも第２成分の融点が第１成分の融点Ｔｍ（℃）よりも低いことを必要としない。
【００１４】
本発明の潜在捲縮性繊維の断面図を、添付の図１〜３に示す。本発明の潜在捲縮性複合繊維において第１成分と第２成分の複合形態は、第２成分を鞘側に配置した偏心鞘芯型とする必要がある。これは複合繊維が同心円構造をとった場合には、熱処理を施しても嵩高性を十分に発現できるだけの捲縮が発現しないためである。偏心鞘芯型の配置は、図１のような断面形状が一般的であるが、図２のように偏心の程度を大きくし、第１成分が一部繊維の表面に露出した形状でも、潜在捲縮性を高めることができるため、本発明の効果が繊維表面に一部露出した第１成分の摩擦により妨げられない程度であるならば採用することができる。さらにまた、図３に示すように、芯成分の断面形状が異形（非円形）である場合も熱収縮の差による潜在捲縮性を高めることができる。
【００１５】
また、複合繊維の第１成分と第２成分の面積比（すなわち繊維を繊維軸方向と直交する方向に切った切断面における鞘成分と芯成分の面積比）が、３５／６５〜６５／３５の範囲であることが好ましく、さらに４５／５５〜５５／４５の範囲であることがより好ましい。これは、第１成分の面積の割合が３５％を大きく下回ると、熱処理時（収縮加工時）に潜在捲縮性によって生じる収縮力が低下するとともに繊維に十分な捲縮を付与させることができないため、嵩高い不織布を得ることができないことがあり、また逆に６５％を大きく超えると、繊維は過剰な収縮を起こすため不織布を均一に収縮させることが困難であり、極端な場合には繊維塊を発生し、不織布を得られない場合があるためである。
【００１６】
本発明の潜在捲縮性複合繊維はウェブに加工した状態で、後述する方法によって測定する熱収縮率が、少なくとも繊維機械方向（以下ＭＤと略称する）において５０％以上であることが好ましく、他の繊維を混綿して用いる場合を考慮すると、ＭＤ６０％以上、ＣＤ（ＭＤに直交する方向）４０％以上の熱収縮率を示すことがより好ましい。ＭＤにおける熱収縮率が５０％を大幅に下回る場合、得られる不織布の嵩は低くなってしまう。
【００１７】
本発明の繊維を製造する方法としては、溶融紡糸法、スパンボンド法、メルトブロー法等の各種公知の紡糸法が例示でき、これらの加工法を適宜使い分けることにより、マルチフィラメント，モノフィラメント，ステープルファイバー，トウ，不織布を得ることができる。
【００１８】
本発明の潜在捲縮性繊維をカード工程を必要とするステープルファイバーとして利用する際には繊維に顕在捲縮を付与する必要があるが、この際一般に用いられる機械捲縮付与手段、いわゆるスタッファーボックス型クリンパーを用いる以外に、第１成分と第２成分の伸長弾性率の差を利用することで、スタッファーボックス型クリンパーを使用せずに、螺旋状立体捲縮を付与することもできる。
【００１９】
またステープルファイバーのような短繊維試料では、繊維をカード機でウェブに加工するためには適切な数の捲縮を付与しなければならない。この捲縮数は繊維の繊度によって適当な範囲があるが、通常は、１０〜２５山／２．５４ｃｍ（１インチ）であることが好ましい。捲縮数がこの範囲を大きく下回る場合には、カード加工時に繊維がシリンダーやドッファに巻き付いたり、ウェブが切れてしまったりといった問題が生じやすくなり、またこの範囲を大きく超える場合には、カード加工時に、ネップが生じ易くなる傾向が認められたり、均一なウェブを得ることが難しくなるといった問題が生じる。嵩高で地合のよい不織布を得るためには前述した範囲内に捲縮数を調節する必要がある。
【００２０】
繊維の繊度は特に限定されるものではなく、繊維の用途に応じて適宜選択されるものである。例えば、使い捨てオムツ、生理用ナプキンの表面材等の吸収性物品等に代表される衛材に用いる場合には、０．１〜１０ｄｔｅｘの範囲、ニードルパンチカーペットやタフテッドカーペット等に用いられる場合には、８〜８０ｄｔｅｘの範囲、モノフィラメント等の土木材料に用いる場合には、５０〜７０００ｄｔｅｘの範囲がそれぞれ好ましい。
【００２１】
溶融紡糸法において、本発明の潜在捲縮性複合繊維を短繊維とした場合、繊維のカット長は特に限定されるものではなく、使用する繊維の加工法、用途に応じて適宜選択すればよい。ローラーカード機またはランダムウエバー等により、ランダムウェブ、パラレルウェブあるいはクロスラップウェブ等の繊維ウェブを得る必要がある場合にはカット長は２０〜１２５ｍｍとすることが好ましく、またカード通過性、不織布の地合いのためには、２５〜７５ｍｍのカット長がより好ましい。また、エアーレイド法、抄紙法により繊維ウェブを製作する場合には、カット長は２０ｍｍ未満とすることが好ましい。
【００２２】
本発明の潜在捲縮性複合繊維を用いて嵩高な不織布を製造するためには、主として本発明の潜在捲縮性複合繊維からなる繊維集合体（ウェブ）に熱処理を施こすことで、繊維の潜在捲縮を発現させると同時に、ウェブを収縮させて一体化する必要がある。加熱処理には、汎用の熱風循環装置や、フローティングドライヤー等の加熱処理装置が使用できるが、ウェブをより均一に収縮させることができるフローティングドライヤーの使用がより好ましい。この装置の特徴はウェブの搬送空間の上面及び下面に設置されたノズルから熱風を噴出し、この熱風によりウェブを浮遊させ、空気搬送と同時に熱収縮を生じさせるためにより均一な不織布が得られることである。しかしながらいずれの装置を使用する場合においてもウェブが切れたり、繊維が飛散することを防ぐために、ニードルパンチ法、エンボスロール法、超音波融着法および／または高圧水流交絡法等の公知の不織布加工法を用いることで、ウェブを仮止めしておくことが重要である。
【００２３】
本発明の潜在捲縮性複合繊維からなる不織布の目付は、使用目的によって適宜選ばれる。例えば、吸収性物品の表面材等に使用される場合には、５〜１００ｇ／ｍ2の範囲、ドレーン材等の土木資材に用いられる場合には、５０〜２０００ｇ／ｍ2の範囲がそれぞれ好ましい。また、不織布は目的に応じて積層することができ、スパンボンド不織布／潜在捲縮性複合繊維からなる不織布／スパンボンド不織布の組み合わせ、スパンボンド不織布／メルトブロー不織布／潜在捲縮性複合繊維からなる不織布の組み合わせ等が例示できる。
【００２４】
また本発明の潜在捲縮性複合繊維は、単独で使用されるだけでなく、本願発明の効果を妨げない範囲であれば、他の繊維と、混綿、混紡、混繊、交編、交繊することなどにより、編織物、繊維成形品等の一次繊維製品とすることができる。また、本発明の繊維は潜在捲縮性を発現させた後には適度な伸縮性と良好な風合いとを有するので、さらに二次加工することにより、肌着、シャツ、ブラウス、靴下、足袋などの衣料分野、中入綿、布団側地、シーツ、ベッドカバー、枕カバー、座布団等の寝装寝具分野、手術用マスク、手術着、キャップ、診察着、ガーゼ、包帯等の医療分野、パップ材等の医薬外分野、生理用品、使い捨て紙おむつ、失禁用パッド等の衛生材料分野、カーペット、カーテン、壁紙等の寝具インテリア分野、靴の内張り材、中敷、履き物素材等の分野、果実保護材、食害防止材等の農園芸用資材、菓子包装材、食品包装材、風呂敷、タオル、おしぼり、たわし、テーブルクロス、エプロン、キッチン布巾、化粧用パフ、ティーパック、ワイピングクロス等のフィルター材分野等の広範囲な分野に使用できる。混綿、混紡、混繊、交編、交繊等に用いる他繊維は特に限定されず、例えばナイロン６、ナイロン６６等のポリアミド系繊維、ポリエチレンテレフタレート、ポリブチレンテレフタレート等のポリエステル系繊維、ポリプロピレン、ポリエチレン及びポリエチレン／ポリプロピレン複合繊維等のポリオレフィン系繊維等が目的に応じて利用できる。
【００２５】
【実施例】
次に、本発明を実施例によって具体的に説明するが、本発明は以下の実施例のみに限定されるものではない。なお、実施例、比較例において用いられている用語の定義及び測定方法は以下の通りである。
（１）融点：（単位 ℃）
ＤｕＰｏｎｔ社製示差走査熱量計ＤＳＣ−１０により、熱可塑性重合体を１０℃／分で昇温した時に得られた融解吸収曲線上のピークに対応する温度をその熱可塑性重合体の融点とした。
（２）ＭＦＲ：（単位 ｇ／１０分）
ＪＩＳ Ｋ ７２１０ 条件１４（２３０℃、２１．１８Ｎ）に準じて測定した。ＭＦＲ（紡糸前）は熱可塑性重合体を試料とし測定した値であり、ＭＦＲ（紡糸後）は、紡糸機により溶融押出した後に採取し、冷却した熱可塑性重合体を試料として測定した値である。
（３）Ｑ値：（重量平均分子量／数平均分子量）
Ｑ値はゲルパーミエイションクロマトグラフ法により求めた、熱可塑性重合体の重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）の比（Ｍｗ／Ｍｎ）である。なお、ここでは紡糸前の熱可塑性重合体の値を示した。
（４）繊度：（単位 ｄｔｅｘ）
繊維を走査型電子顕微鏡によって観察し、得られた画像から１００本の繊維の直径を測定し、その平均値から繊度を算出した。
（５）捲縮数：（単位 山数／２．５４ｃｍ）
短繊維試料については、１０本の繊維について、２．５４ｃｍ当たりの捲縮数を数え、平均した値をここでは捲縮数とした。
（６）熱収縮率：（単位 ％）
２５×２５ｃｍ、目付約２００ｇ／ｍ2のウェブを、クラフト紙にのせて１４５℃に維持した対流型熱風乾燥機に入れ、５分間加熱処理した。熱処理前後のウェブのＭＤ、ＣＤのそれぞれの長さから、熱収縮率を次式により算出した。
熱収縮率（％）＝（１−ａ／２５）×１００
なお、式中のａは熱処理したウェブのＭＤまたはＣＤの長さである。
（７）曳糸性
溶融紡糸法により紡糸したとき、１０時間当りの糸切れの発生回数を測定し、以下の３段階で曳糸性を評価した。
良好：糸切れが発生せず、生産に最も好ましいもの。
良：糸切れ回数が１回以上３回未満のもの。
不良：糸切れ回数が４回以上発生し、生産効率上問題があるもの。
（８）カード適性
原綿５０ｇをミニチュアカード機に投入し、ミニチュアカード機から排出されるウェブと、ミニチュアカード機内の繊維の状態を以下の基準で目視判定した。
適：ウェブが均一であり地合が良く、排出性も良好なもの
不適：原綿がカード機内部のシリンダーやドッファに巻き付き、加工に問題があるもの
（９）地合い
目付約２０ｇ／ｍ2のウェブに、１４５℃に加熱した熱風循環装置中で１分間熱処理を施し、得られた不織布の地合いについて以下のような３段階の基準で目視判定した。
良好：均一に熱収縮を起こし、地合いが良好な不織布が得られたもの
良：ほぼ均一に熱収縮を起こし、地合いの乱れが僅かに見られるものの、実用上問題ないと考えられるもの
不良：熱収縮が均一に起こらず地合いの乱れがあるもの、または収縮率が小さいもの
（１０）風合い
目付約２０ｇ／ｍ2のウェブに、１４５℃に維持した熱風循環装置中で１分間、熱処理を施した。得られた不織布の触感を１０人のパネラーによる官能試験によって、以下の基準で風合いを４段階で採点し、その平均値を四捨五入して評価した。
４：不織布が嵩高く、伸縮性を示すとともに表面が滑らかで柔らかいもの
３：不織布は嵩高く、柔らかいが伸縮性にわずかに欠けるまたは平滑性がないもの
２：不織布に嵩がなく、硬く感じられるとともに伸縮性に欠けるもの
１：ほとんど収縮せず、軽く引っ張っただけで破断してしまうため実用上問題となるもの
（１１）開繊性
スパンボンド紡糸装置により紡糸した繊維を無端ネットコンベア上に捕集し、捕集された長繊維ウェブの開繊状態を目視によって、以下の３段階に評価した。
良好：均一に開繊しているもの
良：ほぼ均一に開繊し、疎密が僅かであるもの
不良：開繊に乱れがあり、製品として使用できないと考えられるもの
【００２６】
実施例1〜８、比較例1〜３
エチレン−プロピレン−ブテン−１三元共重合体、エチレン−プロピレン二元共重合体、結晶性ポリプロピレンのいずれかを第１成分として用い、高密度ポリエチレン、直鎖状低密度ポリエチレン、低密度ポリエチレン、ポリエステル（固有粘度（Ｉ．Ｖ．値）０．６７）、結晶性ポリプロピレンのいずれかを第２成分とし、押出機、孔径０．８ｍｍの偏心鞘芯型紡糸口金、並列型紡糸口金もしくは同心鞘芯型紡糸口金のいずれか一種と、巻取り装置等を備えた紡糸装置と、多段加熱ロールとスタッファーボックス型クリンパーを備えた延伸装置を用い、複合繊維を製造し、得られた繊維の熱収縮率を測定した。
【００２７】
それぞれの複合繊維及び不織布のデータについては、実施例１〜８を表１〜２に、比較例１〜３を表３に示した。
【００２８】
【表１】
【表２】
【表３】
比較例１では、第１成分に用いた結晶性ポリプロピレン（エチレン成分を０．２４重量％含む）が、熱収縮性に乏しいため、製造した複合繊維に熱処理を施しても十分な捲縮が発現せず熱収縮率が極端に低くなっていた。また、比較例２については、第１成分が実施例２と同じものを用いたが、第２成分として用いたポリエステルの剛性が高いために、熱収縮が起こらず、嵩高な不織布は得られなかった。比較例３は複合形態が同心となっているため、充分な捲縮が得られていない。さらに比較例１〜３については１４５℃の熱風では繊維が収縮せず、不織布を得ることができなかった。
【００３２】
実施例９〜１２、比較例４〜５
エチレン−プロピレン−ブテン−１三元共重合体、エチレン−プロピレン二元共重合体、結晶性ポリプロピレンのいずれかを第１成分として用い、高密度ポリエチレン、直鎖状低密度ポリエチレン、結晶性ポリプロピレン、エチレン−プロピレン−ブテン−１三元共重合体のいずれかを第２成分として、スパンボンド紡糸装置、繊維断面に応じた口金を用い複合長繊維を紡糸した。紡糸口金から吐出した複合繊維群はエアーサッカーに導入して牽引延伸し、複合長繊維を得、続いてエアーサッカーより排出された前記長繊維群を、帯電装置により同電荷を付与せしめ帯電させた後、反射板に衝突させて開繊し、開繊した長繊維群を裏面に吸引装置を設けた無端ネット状コンベア上に、長繊維ウエブとして捕集した。
【００３３】
それぞれの複合繊維及び不織布のデータについては、実施例９〜１２を表３に、比較例４〜５を表４に示した。
【００３４】
【表４】
【表５】
比較例４では、複合形態が同心鞘芯であったため、製造した不織布に熱処理を施しても捲縮は生じず、加えて熱処理により長繊維層間に熱接着が生じていないことから不織布は得られなかった。また、比較例５については第２成分が繊維表面摩擦が高いプロピレン共重合体であったため、熱収縮率は高かったが開繊性不良のため不織布が得られなかった。
【００３７】
【発明の効果】
本発明の潜在捲縮性複合繊維は、特定の範囲の共重合組成を有するプロピレン共重合体を複合繊維の繊維形成成分として使用することで、以下の優れた効果がある。
（１）熱処理によりウエブ中の繊維に潜在捲縮を発現させるのと同時に不織布化できるため、不織布の生産性に優れる。
（２）熱処理によりウェブ中の繊維に潜在捲縮を発現させることできるため、嵩高な不織布が得られる。特に機械捲縮付与手段を使用できないスパンボンド法、メルトブロー法によって紡糸された長繊維に捲縮を付与でき、嵩高な不織布を得ることが可能となった。
（３）短繊維の場合、繊維表面の摩擦を低減させたことによりカード加工時に均一なウエブを得ることができる。またウェブに熱処理を施し捲縮を発現させることで嵩高で良好な地合の不織布が得られる。
【図面の簡単な説明】
【図１】偏心鞘芯型複合繊維の断面図
【図２】偏心鞘芯型複合繊維の断面図（偏心の度合いを高めたもの）
【図３】異形の芯を有する偏心鞘芯型複合繊維の断面図
【符号の説明】
１ 偏心鞘芯形複合繊維を構成する第２成分
２ 偏心鞘芯形複合繊維を構成する第１成分
３ 並列型複合繊維を構成する第２成分
４ 並列型複合繊維を構成する第１成分
５ 複合繊維を構成する第２成分
６ 複合繊維を構成する第１成分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyolefin-based composite fiber having a latent crimp property in which crimp is developed by heat treatment and a nonwoven fabric using the same.
[0002]
[Prior art]
Conventionally, as one of the methods for obtaining a bulky nonwoven fabric, a zigzag-type mechanical crimped fiber using a crimping means such as a crimper, or a composite form of fibers as a parallel type or an eccentric sheath core type, There has been a method of using a fiber to which a helical three-dimensional crimp is imparted by causing strain inside the fiber by means such as stretching.
[0003]
For example, Japanese Patent Laid-Open No. 2-191720 proposes a sheath-core type composite fiber in which an ethylene-propylene random copolymer is mainly disposed as a sheath component and crystalline polypropylene is disposed as a core component. This is because heat treatment is applied to the web made of this fiber to utilize the heat shrinkage characteristics of the ethylene-propylene random copolymer used as the sheath component, to develop latent crimps during the processing of the nonwoven fabric, and to create a bulky nonwoven fabric. To manufacture. However, the metal friction resistance of the ethylene-propylene random copolymer disposed in the sheath component is generally much higher than that of other resins used for fibers, such as high-density polyethylene. There is a problem that it is difficult to obtain a web, and even in the obtained nonwoven fabric, there was a peculiar slimy feeling and sticky feeling due to the characteristics of the resin of the sheath component. In addition, raw cotton is generally opened by a spreader and transported to a card machine by a blower tube. However, a fiber having a high metal frictional resistance has a problem of poor transportability in which cotton adheres to the wall surface of the blower tube. Furthermore, even when composite long fibers are spun by combining these resins by the spunbond method that does not require a carding process, the fibers are opened due to the high inter-fiber friction of the ethylene-propylene random copolymer covering the fiber surface. There was a problem that the web accumulated on the conveyor was not sufficiently uniform due to poor fineness. As described above, to date, no bulky and good-quality nonwoven fabrics using fibers having latent crimpability have been obtained, but in recent years, competition for paper diapers and sanitary products has intensified. In addition, there is an increasing demand for a non-woven fabric with a better texture and bulk.
[0004]
[Problems to be solved by the invention]
This invention solves the said problem, and makes it a subject to provide the latent crimpable conjugate fiber used as the raw material and the nonwoven fabric which is bulky and favorable in texture.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found the following means and have completed the present invention. The present invention has the following configuration.
(1) A propylene copolymer having a melting point Tm (° C.) of 120 ≦ Tm ≦ 147, 90 to 98% by weight of propylene and 2 to 10% by weight of an α-olefin other than propylene is used as a first component, and polyethylene is used. A composite fiber as a second component, wherein the composite form of the first component and the second component is an eccentric sheath core type in which the second component is disposed on the sheath side, and the first component and the second component in the fiber cross section The area ratio of the components is 65/35 to 35/65,In the state in which the composite fiber is processed into a web, the thermal shrinkage in the fiber machine direction (MD) measured by the following method is 50% or more.Latent crimped composite fiber.
25 × 25cm, weight per unit area: about 200g / m 2 Is placed in a convection hot air dryer maintained at 145 ° C. on kraft paper and heat-treated for 5 minutes. From the length of the MD of the web before and after the heat treatment, the thermal shrinkage rate is calculated by the following formula.
Thermal contraction rate (%) = (1−a / 25) × 100
In the formula, a is the MD length of the heat-treated web.
(2) The latent cage as described in (1) above, wherein the first component is a propylene copolymer comprising 90 to 96% by weight of propylene and 4 to 10% by weight of an α-olefin other than propylene. Shrinkable composite fiber.
(3) The first component is an ethylene-propylene-butene-1 terpolymer comprising 90 to 96% by weight of propylene, 3 to 7% by weight of ethylene and 1 to 5% by weight of butene-1. The latent crimpable conjugate fiber according to any one of (1) to (2).
(4) The second component comprises at least one selected from high-density polyethylene, linear low-density polyethylene, and low-density polyethylene, as described in any one of (1) to (3) above, Latent crimped composite fiber.
(5) The latent crimpability according to any one of (1) to (4) above, wherein the second component is polyethylene having a melting point lower than the melting point Tm (° C.) of the first component. Composite fiber.
(6) The latent crimpable conjugate fiber according to any one of (1) to (5), wherein the latent crimpable conjugate fiber is a long fiber.
(7) A propylene copolymer having a melting point Tm (° C.) of 120 ≦ Tm ≦ 147, 90 to 98% by weight of propylene and 2 to 10% by weight of an α-olefin other than propylene is used as a first component, and polyethylene is used. A composite fiber as a second component, wherein the composite form of the first component and the second component is an eccentric sheath core type in which the second component is disposed on the sheath side, and the first component and the second component in the fiber cross section The area ratio of the components is 65/35 to 35/65, and is obtained using a latent crimpable conjugate fiber. The thermal shrinkage ratio in the fiber machine direction (MD) measured by the following method is 50. % Web.
25 × 25cm, weight per unit area: about 200g / m2Is placed in a convection hot air dryer maintained at 145 ° C. on kraft paper and heat-treated for 5 minutes. From the MD length of the web before and after the heat treatment, the thermal shrinkage rate is calculated by the following formula.
Thermal contraction rate (%) = (1−a / 25) × 100
In addition, a in a type | formula is the length of MD of the heat-processed web.
(8) A nonwoven fabric using the latent crimpable conjugate fiber according to any one of (1) to (6) or the web according to (7).
(9) Using the latent crimpable conjugate fiber according to any one of (1) to (6) or the web according to (7), the melting point of the second component is equal to or lower than the melting point of the first component. Heat treatment in the above temperature range, fabricate and shrink at the same time, or entangle the fibers by developing crimps by heat treatment at a low temperature (below the melting point of both components) at which the fibers are not thermally bonded to each other A method for producing a nonwoven fabric, characterized in that the nonwoven fabric is produced only by allowing the nonwoven fabric to be produced.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Specific embodiments of the present invention are shown below.
As a 1st component which comprises the latent crimpable composite fiber of this invention, melting | fusing point Tm (degreeC) which raise | generates heat shrink at a comparatively low temperature and has fiber formation from the point of workability is 120 <= Tm <=. Examples include propylene copolymers in the range of 147. Such a propylene copolymer can be obtained by copolymerizing mainly propylene and other α-olefins. Examples of such α-olefins include ethylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, 4-methyl-pentene-1, and these α-olefins. Two or more of them can be used in combination. Specific examples of the propylene copolymer include an ethylene-propylene binary copolymer, a propylene-butene-1 binary copolymer, an ethylene-propylene-butene-1 ternary copolymer, and a propylene-hexene-1 binary copolymer. Examples thereof include polymers, propylene-octene-1 binary copolymers, and mixtures thereof. These copolymers are usually random copolymers but may be block copolymers.
[0007]
Among propylene copolymers that can be used as the first component of the latent crimpable fiber of the present invention and have a melting point Tm (° C.) within the range described above, 90 to 98% by weight of propylene, 1 to 7% by weight Ethylene-propylene-butene-1 terpolymer composed of ethylene, 1 to 5% by weight of butene-1; and ethylene-propylene binary copolymer composed of 90 to 98% by weight of propylene and 2 to 10% by weight of ethylene. A polymer is preferable from the viewpoint of cost, and from the viewpoint of low-temperature processability and shrinkage force when shrinking by heat, as a first component, ethylene comprising 90 to 96% by weight of propylene and 4 to 10% by weight of ethylene Ethylene-propylene-butene-1 ternary copolymer consisting of propylene binary copolymer, 90-96 wt% propylene, 3-7 wt% ethylene, 1-5 wt% butene-1 It is more preferable to use a union. In these resins, those having a melting point Tm (° C.) of less than 120 ° C. exhibit rubber elasticity and thus adversely affect the card processability of the obtained fibers. In addition, when a propylene copolymer having a melting point Tm (° C.) exceeding 147 ° C. is used as the first component, the shrinkability of the obtained fiber is reduced to the level of ordinary polypropylene single component fiber or polyethylene / polypropylene composite fiber. Resulting in. Therefore, by using a propylene copolymer having a composition within the range described above as the first component, a latent crimpable fiber having both card processability and heat shrinkability can be obtained. In addition, as long as the heat shrinkability of the fiber of the present invention is not extremely reduced or the heat shrinkability is moderately suppressed, titanium dioxide, calcium carbonate, magnesium hydroxide and the like may be included in the first component as necessary. Inorganic substances, flame retardants, pigments and other polymers may be added.
[0008]
Examples of the polyethylene that can be used as the second component of the latent crimpable fiber of the present invention include high-density polyethylene, linear low-density polyethylene, and low-density polyethylene that are broadly classified by melting point and density classification as described below. be able to.
[0009]
The high density polyethylene referred to in the present invention is a polymer of ethylene alone or a small amount of C3-C12 alkene, usually up to 2% by weight, polymerized by a low pressure method using a known Ziegler-Natta catalyst. Ethylene copolymer contained as a comonomer, generally 0.941 to 0.965 g / cmThreeAnd a polyethylene having a melting point of 127 ° C. or higher.
[0010]
The linear low density polyethylene as used in the present invention is a comonomer of a C3-C12 alkene polymerized using a known Ziegler-Natta catalyst and having no substantial long-branched chain, usually in a proportion of 15% by weight or less. As an ethylene-based copolymer contained in general as 0.925 to 0.940 g / cm.ThreeAnd a polyethylene having a melting point of less than 127 ° C.
[0011]
The low density polyethylene referred to in the present invention is generally polymerized by a high pressure method, and generally has a density of 0.910 to 0.940 g / cm.ThreeIn addition, polyethylene having a large number of branched chains and low crystallinity and having a melting point of 120 ° C. or lower.
[0012]
Furthermore, polyethylene resins polymerized using a metallocene catalyst have a lower melting point than the above resins, which is advantageous in terms of low-temperature processability when heat-bonding fibers together, and at the same time a narrow molecular weight distribution Therefore, it can be used suitably as the second component of the present invention. In addition, in producing the latent crimpable fiber of the present invention, in order to impart low temperature processability and process stability, several kinds of resins selected from these polyethylenes are mixed, or the object of the present invention is achieved. If necessary, inorganic substances such as titanium dioxide, calcium carbonate and magnesium hydroxide, flame retardants, pigments and other polymers may be added to the second component as necessary.
[0013]
In the latently crimpable fiber of the present invention, thermal adhesiveness can be imparted to the fiber by using polyethylene having a melting point lower than the melting point Tm (° C.) of the first component as the second component. In other words, if the resin is appropriately selected so that the first component and the second component have a melting point difference as required, the fibers are entangled with each other by a technique such as embossing and heat pinning. The strength of the nonwoven fabric can be improved and the stretchability can be adjusted within a range that does not impair the texture and bulkiness of the nonwoven fabric. In particular, when the heat treatment is performed in a temperature range not higher than the melting point of the first component and not lower than the melting point of the second component, the nonwoven fabric production process and the shrinkage treatment can be performed simultaneously, so that the nonwoven fabric manufacturing process can be simplified. At this time, the melting point of the second component is preferably 5 ° C. or more, more preferably 10 ° C. or more lower than the melting point Tm (° C.) of the first component. Moreover, depending on the use of a nonwoven fabric, a nonwoven fabric can also be manufactured only by making a crimp express by the heat processing by the low temperature (less than melting | fusing point of both components) which does not heat-bond fibers, and entanglement of a fiber. If a non-woven fabric that can withstand practical use can be obtained simply by developing latent crimp due to heat shrinkage at a temperature lower than the melting point of both components, the melting point of the second component is not necessarily higher than the melting point Tm (° C.) of the first component. You don't need to be low.
[0014]
A cross-sectional view of the latent crimpable fiber of the present invention is shown in the attached FIGS. In the latent crimpable conjugate fiber of the present invention, the composite form of the first component and the second component needs to be an eccentric sheath core type in which the second component is arranged on the sheath side. This is because when the conjugate fiber has a concentric structure, crimps sufficient to exhibit bulkiness are not exhibited even when heat treatment is performed. The arrangement of the eccentric sheath core type is generally a cross-sectional shape as shown in FIG. 1, but even if the degree of eccentricity is increased as shown in FIG. 2 and the first component is partially exposed on the fiber surface, Since the crimpability can be enhanced, the present invention can be adopted as long as the effect of the present invention is not hindered by the friction of the first component partially exposed on the fiber surface. Furthermore, as shown in FIG. 3, even when the cross-sectional shape of the core component is irregular (non-circular), the latent crimpability due to the difference in thermal shrinkage can be enhanced.
[0015]
Further, the area ratio of the first component and the second component of the composite fiber (that is, the area ratio of the sheath component to the core component in the cut surface obtained by cutting the fiber in the direction perpendicular to the fiber axis direction) is 35/65 to 65/35 It is preferable that it is the range of 45, and it is more preferable that it is the range of 45 / 55-55 / 45. This is because if the area ratio of the first component is much less than 35%, the shrinkage force generated by latent crimping during heat treatment (during shrinkage processing) is reduced and sufficient crimp cannot be imparted to the fiber. Therefore, it may not be possible to obtain a bulky nonwoven fabric, and conversely if it exceeds 65%, the fiber causes excessive shrinkage, making it difficult to uniformly shrink the nonwoven fabric. This is because lumps may be generated and the nonwoven fabric may not be obtained.
[0016]
The latent crimpable conjugate fiber of the present invention is preferably processed in a web and has a thermal shrinkage rate of 50% or more at least in the fiber machine direction (hereinafter abbreviated as MD) as measured by the method described below. Considering the case of using mixed fibers, it is more preferable to show a heat shrinkage rate of MD 60% or more and CD (direction perpendicular to MD) 40% or more. If the thermal shrinkage in MD is significantly less than 50%, the resulting nonwoven fabric will have a low bulk.
[0017]
Examples of the method for producing the fiber of the present invention include various known spinning methods such as a melt spinning method, a spun bond method, and a melt blow method. By appropriately using these processing methods, a multifilament, a monofilament, a staple fiber, Tow and non-woven fabric can be obtained.
[0018]
When the latent crimpable fiber of the present invention is used as a staple fiber that requires a carding process, it is necessary to impart an actual crimp to the fiber. In this case, a mechanical crimp imparting means generally used, a so-called stuffer box In addition to using a type crimper, a spiral three-dimensional crimp can also be imparted without using a stuffer box type crimper by utilizing the difference in elongation modulus between the first component and the second component.
[0019]
Also, for short fiber samples such as staple fibers, an appropriate number of crimps must be applied in order to process the fibers into a web with a card machine. The number of crimps has an appropriate range depending on the fineness of the fiber, but it is usually preferable that the number of crimps is 10 to 25 peaks / 2.54 cm (1 inch). If the number of crimps is significantly below this range, problems such as fiber winding around the cylinder or doffer or web breakage may occur during card processing. Occasionally, there is a problem that a tendency to easily generate neps is recognized, and it is difficult to obtain a uniform web. In order to obtain a bulky and well-formed nonwoven fabric, it is necessary to adjust the number of crimps within the aforementioned range.
[0020]
The fineness of the fiber is not particularly limited, and is appropriately selected according to the use of the fiber. For example, when used for sanitary materials represented by absorbent articles such as disposable diapers and sanitary napkin surface materials, the range of 0.1 to 10 dtex, when used for needle punched carpets, tufted carpets, etc. Is preferably in the range of 8 to 80 dtex, and in the range of 50 to 7000 dtex when used for civil engineering materials such as monofilaments.
[0021]
In the melt spinning method, when the latent crimpable conjugate fiber of the present invention is a short fiber, the cut length of the fiber is not particularly limited, and may be appropriately selected depending on the processing method and use of the fiber to be used. . When it is necessary to obtain a fiber web such as a random web, a parallel web or a cross-wrap web by a roller card machine or a random weber, the cut length is preferably 20 to 125 mm. Therefore, a cut length of 25 to 75 mm is more preferable. Moreover, when producing a fiber web by an air raid method or a papermaking method, it is preferable that the cut length is less than 20 mm.
[0022]
In order to produce a bulky nonwoven fabric using the latent crimpable conjugate fiber of the present invention, the fiber assembly (web) mainly composed of the latent crimpable conjugate fiber of the present invention is subjected to heat treatment, At the same time that the latent crimp is developed, it is necessary to shrink and integrate the web. For the heat treatment, a general-purpose hot air circulation device or a heat treatment device such as a floating dryer can be used, but the use of a floating dryer that can shrink the web more uniformly is more preferable. The feature of this device is that hot air is blown out from nozzles installed on the upper and lower surfaces of the web conveyance space, the web is floated by this hot air, and heat shrinkage occurs simultaneously with air conveyance, so that a more uniform nonwoven fabric can be obtained. It is. However, in order to prevent the web from being cut or the fibers from being scattered when using any of the apparatuses, known nonwoven fabric processing such as needle punching, embossing roll, ultrasonic fusion and / or high-pressure hydroentanglement It is important to temporarily fix the web by using the method.
[0023]
The basis weight of the nonwoven fabric composed of the latent crimpable conjugate fiber of the present invention is appropriately selected depending on the purpose of use. For example, when used as a surface material for absorbent articles, 5 to 100 g / m2Range, 50-2000 g / m when used for civil engineering materials such as drain materials2Each of these ranges is preferred. In addition, the nonwoven fabric can be laminated according to the purpose, and the combination of spunbond nonwoven fabric / nonwoven fabric composed of latent crimpable conjugate fiber / spunbond nonwoven fabric, spunbond nonwoven fabric / melt blown nonwoven fabric / nonwoven fabric composed of latent crimpable conjugate fiber. The combination of these etc. can be illustrated.
[0024]
Further, the latent crimpable conjugate fiber of the present invention is not only used alone, but is mixed with other fibers as long as the effect of the present invention is not hindered. By doing so, primary fiber products such as knitted fabrics and fiber molded products can be obtained. Moreover, since the fibers of the present invention have moderate stretchability and good texture after the latent crimpability is expressed, by further secondary processing, clothing such as underwear, shirts, blouses, socks, tabi, etc. Field, Bedding, Futon side, Bed sheet, Bed cover, Pillow cover, Bedding bedding field such as Surgical mask, Surgical mask, Surgical clothes, Cap, Examination dress, Medical field such as Gauze, Bandage, Pap material etc. Non-medicine fields, sanitary products, disposable diapers, sanitary materials such as incontinence pads, carpets, curtains, bedding interiors such as wallpaper, shoes lining materials, insoles, footwear materials, fruit protection materials, food damage prevention Agricultural and horticultural materials such as ingredients, confectionery packaging materials, food packaging materials, furoshiki, towels, towels, towels, tablecloths, aprons, kitchen cloths, cosmetic puffs, tea packs, wiping cloths, etc. It can be used in a wide variety of fields such as Iruta material field. Other fibers used for blended cotton, blended fibers, blended fibers, knitted fabrics, woven fabrics, etc. are not particularly limited. For example, polyamide fibers such as
[0025]
【Example】
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited only to a following example. The definitions of terms used in Examples and Comparative Examples and the measurement methods are as follows.
(1) Melting point: (unit: ° C)
Using a differential scanning calorimeter DSC-10 manufactured by DuPont, the temperature corresponding to the peak on the melt absorption curve obtained when the temperature of the thermoplastic polymer was raised at 10 ° C./min was defined as the melting point of the thermoplastic polymer.
(2) MFR: (Unit: g / 10 minutes)
It measured according to JISK7210 condition 14 (230 degreeC, 21.18N). MFR (before spinning) is a value measured using a thermoplastic polymer as a sample, and MFR (after spinning) is a value measured using a thermoplastic polymer sampled after being melt-extruded by a spinning machine and cooled. .
(3) Q value: (weight average molecular weight / number average molecular weight)
The Q value is a ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the thermoplastic polymer obtained by gel permeation chromatography. Here, the value of the thermoplastic polymer before spinning is shown.
(4) Fineness: (unit: dtex)
The fiber was observed with a scanning electron microscope, the diameter of 100 fibers was measured from the obtained image, and the fineness was calculated from the average value.
(5) Number of crimps: (unit: number of mountains / 2.54 cm)
For the short fiber sample, the number of crimps per 2.54 cm was counted for 10 fibers, and the average value was used as the number of crimps.
(6) Thermal contraction rate: (unit:%)
25 x 25 cm, weight per unit area: 200 g / m2The web was placed in a convection hot air dryer maintained at 145 ° C. on kraft paper and heat treated for 5 minutes. From the respective lengths of the MD and CD of the web before and after the heat treatment, the thermal shrinkage rate was calculated by the following formula.
Thermal contraction rate (%) = (1−a / 25) × 100
In the formula, a is the MD or CD length of the heat-treated web.
(7) Spinnability
When spinning by the melt spinning method, the number of occurrences of yarn breakage per 10 hours was measured, and the spinnability was evaluated in the following three stages.
Good: No thread breakage, most preferred for production.
Good: The thread breakage is 1 or more and less than 3 times.
Defect: The thread breakage occurs more than 4 times, and there is a problem in production efficiency.
(8) Card suitability
50 g of raw cotton was put into a miniature card machine, and the web discharged from the miniature card machine and the state of fibers in the miniature card machine were visually determined according to the following criteria.
Suitable: Uniform web, good texture, good discharge
Inappropriate: Raw cotton wraps around the cylinder or doffer inside the card machine, causing problems in processing
(9) Feelings
About 20g / m2The web was heat-treated in a hot air circulating apparatus heated to 145 ° C. for 1 minute, and the texture of the obtained nonwoven fabric was visually determined according to the following three-stage criteria.
Good: Non-woven fabric with uniform heat shrinkage and good texture
Good: Heat shrinkage occurs almost uniformly, and there is a slight disturbance in the texture, but there is no problem in practical use.
Defect: Heat shrinkage does not occur uniformly and the texture is disturbed, or the shrinkage rate is small
(10) Texture
About 20g / m2The web was heat treated for 1 minute in a hot air circulating apparatus maintained at 145 ° C. The texture of the obtained nonwoven fabric was evaluated by a sensory test with 10 panelists based on the following criteria. The texture was scored in four stages, and the average value was rounded off.
4: Nonwoven fabric is bulky, has elasticity and has a smooth and soft surface
3: Non-woven fabric is bulky and soft but lacks stretchability or has no smoothness
2: The nonwoven fabric is not bulky and feels hard and lacks elasticity
1: Practically problematic because it hardly breaks and breaks when pulled lightly
(11) Spreadability
The fibers spun by the spunbond spinning device were collected on an endless net conveyor, and the opened state of the collected long fiber web was visually evaluated in the following three stages.
Good: Uniformly spread
Good: Opened almost uniformly, with little or no density
Defect: There is a disorder in opening, and it is considered that the product cannot be used.
[0026]
Examples 1-8, Comparative Examples 1-3
One of ethylene-propylene-butene-1 terpolymer, ethylene-propylene binary copolymer, and crystalline polypropylene is used as the first component, and high-density polyethylene, linear low-density polyethylene, low-density polyethylene, Either polyester (intrinsic viscosity (IV value) 0.67) or crystalline polypropylene is used as the second component, an extruder, an eccentric sheath core spinneret with a hole diameter of 0.8 mm, a parallel spinneret or a concentric sheath Using one of the core-type spinneret, a spinning device equipped with a winding device, and a drawing device equipped with a multistage heating roll and a stuffer box-type crimper, a composite fiber is produced, and the resulting fiber is subjected to heat shrinkage. The rate was measured.
[0027]
About the data of each conjugate fiber and nonwoven fabric, Examples 1-8 were shown in Tables 1-2, and Comparative Examples 1-3 were shown in Table 3.
[0028]
[Table 1]
[Table 2]
[Table 3]
In Comparative Example 1, the crystalline polypropylene used for the first component (containing 0.24% by weight of the ethylene component) is poor in heat shrinkage, so that sufficient crimp is developed even when the manufactured composite fiber is subjected to heat treatment. The heat shrinkage rate was extremely low. Moreover, about the comparative example 2, although the 1st component used the same thing as Example 2, since the rigidity of polyester used as a 2nd component is high, heat shrink does not occur and a bulky nonwoven fabric is not obtained. It was. In Comparative Example 3, since the composite form is concentric, sufficient crimps are not obtained. Further, for Comparative Examples 1 to 3, the fiber was not shrunk by hot air at 145 ° C., and a nonwoven fabric could not be obtained.
[0032]
Examples 9-12, Comparative Examples 4-5
One of ethylene-propylene-butene-1 terpolymer, ethylene-propylene binary copolymer, and crystalline polypropylene is used as the first component, and high-density polyethylene, linear low-density polyethylene, crystalline polypropylene, Using any one of the ethylene-propylene-butene-1 terpolymer as the second component, a composite long fiber was spun using a spunbond spinning device and a die corresponding to the fiber cross section. The composite fiber group discharged from the spinneret was introduced into air soccer and pulled and drawn to obtain a composite long fiber, and then the long fiber group discharged from the air soccer was charged by applying the same charge with a charging device. Thereafter, the fibers were opened by colliding with a reflecting plate, and the opened long fiber group was collected as a long fiber web on an endless net-like conveyor provided with a suction device on the back surface.
[0033]
About the data of each composite fiber and nonwoven fabric, Examples 9-12 were shown in Table 3, and Comparative Examples 4-5 were shown in Table 4.
[0034]
[Table 4]
[Table 5]
In Comparative Example 4, since the composite form was a concentric sheath core, crimping did not occur even if the manufactured nonwoven fabric was heat-treated, and in addition, no heat-bonding occurred between the long fiber layers due to the heat treatment, so a nonwoven fabric was obtained. There wasn't. In Comparative Example 5, since the second component was a propylene copolymer having high fiber surface friction, the heat shrinkage ratio was high, but a nonwoven fabric was not obtained due to poor fiber opening.
[0037]
【The invention's effect】
The latent crimpable conjugate fiber of the present invention has the following excellent effects by using a propylene copolymer having a specific range of copolymer composition as a fiber-forming component of the conjugate fiber.
(1) Since the nonwoven fabric can be made into a nonwoven fabric at the same time as latent crimp is developed in the fibers in the web by heat treatment, the productivity of the nonwoven fabric is excellent.
(2) Since the latent crimps can be expressed in the fibers in the web by heat treatment, a bulky nonwoven fabric is obtained. In particular, crimps can be imparted to long fibers spun by a spunbond method or a melt blow method in which a mechanical crimp imparting means cannot be used, and a bulky nonwoven fabric can be obtained.
(3) In the case of short fibers, a uniform web can be obtained during card processing by reducing the friction on the fiber surface. Moreover, the nonwoven fabric of a bulky and favorable formation is obtained by heat-treating a web and expressing a crimp.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an eccentric sheath-core type composite fiber
FIG. 2 is a cross-sectional view of an eccentric sheath-core type composite fiber (with a higher degree of eccentricity).
FIG. 3 is a cross-sectional view of an eccentric sheath core type composite fiber having a deformed core.
[Explanation of symbols]
1 Second component of the eccentric sheath-core composite fiber
2 The first component constituting the eccentric sheath-core composite fiber
3 Second component of the parallel composite fiber
4 1st component which comprises parallel type composite fiber
5 Second component of the composite fiber
1st component constituting 6 composite fiber
Claims (9)
２５×２５ｃｍ、目付約２００ｇ／ｍ ２ のウェブを、クラフト紙にのせて１４５℃に維持した対流型熱風乾燥機に入れ、５分間加熱処理する。熱処理前後のウェブのＭＤの長さから、熱収縮率を次式により算出する。
熱収縮率（％）＝（１−ａ／２５）×１００
なお、式中のａは熱処理したウェブのＭＤの長さである。 A propylene copolymer having a melting point Tm (° C.) of 120 ≦ Tm ≦ 147, 90 to 98% by weight of propylene and 2 to 10% by weight of an α-olefin other than propylene is used as the first component, and polyethylene is the second component. A composite fiber of the first component and the second component is an eccentric sheath core type in which the second component is disposed on the sheath side, and the areas of the first component and the second component in the fiber cross section The ratio is 65/35 to 35/65 , and the heat shrinkage in the fiber machine direction (MD) measured by the following method in a state where the composite fiber is processed into a web is 50% or more. , Latent crimpable composite fiber.
A web of 25 × 25 cm and a basis weight of about 200 g / m 2 is placed in a convection type hot air dryer maintained at 145 ° C. on kraft paper and heat-treated for 5 minutes. From the length of the MD of the web before and after the heat treatment, the thermal shrinkage rate is calculated by the following formula.
Thermal contraction rate (%) = (1−a / 25) × 100
In the formula, a is the MD length of the heat-treated web.
２５×２５ｃｍ、目付約２００ｇ／ｍ２のウェブを、クラフト紙にのせて１４５℃に維持した対流型熱風乾燥機に入れ、５分間加熱処理する。熱処理前後のウェブのＭＤの長さから、熱収縮率を次式により算出する。
熱収縮率（％）＝（１−ａ／２５）×１００
なお、式中のａは熱処理したウェブのＭＤの長さである。A propylene copolymer having a melting point Tm (° C.) of 120 ≦ Tm ≦ 147, 90 to 98% by weight of propylene and 2 to 10% by weight of an α-olefin other than propylene is used as the first component, and polyethylene is the second component. A composite fiber of the first component and the second component is an eccentric sheath core type in which the second component is disposed on the sheath side, and the areas of the first component and the second component in the fiber cross section The ratio is 65/35 to 35/65 and is obtained using a latent crimpable conjugate fiber, and the thermal shrinkage in the fiber machine direction (MD) measured by the following method is 50% or more. Yes, the web.
A web of 25 × 25 cm and a basis weight of about 200 g / m 2 is placed in a convection type hot air dryer maintained at 145 ° C. on kraft paper and heat-treated for 5 minutes. From the length of the MD of the web before and after the heat treatment, the thermal shrinkage rate is calculated by the following formula.
Thermal contraction rate (%) = (1−a / 25) × 100
In the formula, a is the MD length of the heat-treated web.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000148894A JP4433567B2 (en) | 1999-05-21 | 2000-05-19 | Latent crimpable conjugate fiber and nonwoven fabric using the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14235899 | 1999-05-21 | ||
| JP11-142358 | 1999-05-21 | ||
| JP2000148894A JP4433567B2 (en) | 1999-05-21 | 2000-05-19 | Latent crimpable conjugate fiber and nonwoven fabric using the same |
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| Publication Number | Publication Date |
|---|---|
| JP2001040531A JP2001040531A (en) | 2001-02-13 |
| JP4433567B2 true JP4433567B2 (en) | 2010-03-17 |
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| JP2000148894A Expired - Fee Related JP4433567B2 (en) | 1999-05-21 | 2000-05-19 | Latent crimpable conjugate fiber and nonwoven fabric using the same |
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100436667C (en) * | 2003-08-28 | 2008-11-26 | 大和纺织株式会社 | Potential crimping composite fiber and method for production thereof, and fiber aggregate, and nonwoven fabric |
| JP4212526B2 (en) * | 2004-08-05 | 2009-01-21 | 花王株式会社 | Three-dimensional sheet material |
| CN101522964B (en) * | 2006-10-03 | 2013-07-31 | 大和纺控股株式会社 | Crimping conjugate fiber and fiber assembly using the composite fiber |
| JP5037964B2 (en) | 2007-02-13 | 2012-10-03 | Ｅｓファイバービジョンズ株式会社 | Wet non-woven fabric |
| JP5631035B2 (en) * | 2010-03-29 | 2014-11-26 | ユニ・チャーム株式会社 | Nonwoven sheet |
| KR102384025B1 (en) * | 2016-03-23 | 2022-04-07 | 이노악 코포레이션 | Cosmetic holding body and cosmetic container in which it is accommodated |
| JP6365733B2 (en) * | 2016-06-14 | 2018-08-01 | 王子ホールディングス株式会社 | Nonwovens and absorbent articles |
| JP6753182B2 (en) * | 2016-07-15 | 2020-09-09 | 東レ株式会社 | Aromatic polyester composite fiber |
| WO2023234224A1 (en) * | 2022-06-03 | 2023-12-07 | エム・エーライフマテリアルズ株式会社 | Nonwoven fabric laminate |
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2000
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| JP2001040531A (en) | 2001-02-13 |
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