JP4453179B2

JP4453179B2 - Split fiber and fiber molded body using the same

Info

Publication number: JP4453179B2
Application number: JP2000280617A
Authority: JP
Inventors: 満小島; 聡彦筒井
Original assignee: Chisso Corp
Current assignee: JNC Corp
Priority date: 2000-09-14
Filing date: 2000-09-14
Publication date: 2010-04-21
Anticipated expiration: 2020-09-14
Also published as: JP2002088580A

Description

【０００１】
【発明の属する技術分野】
本発明は、分割性に優れた分割型複合繊維に関する。さらに詳しくはバッテリセパレーター、ワイパー、フィルターなどの産業資材分野、おむつ、ナプキンなどの衛生材料分野、また衣料分野にも好適に用いることのできる分割性に優れた分割型複合繊維及びこれを用いた繊維成形体及び積層繊維成形体に関する。
【０００２】
【従来の技術】
従来、極細繊維を得る方法として、海島型や分割型の複合繊維が知られている。海島型複合繊維を用いる方法は、複数成分を組み合せて紡糸して海島型複合繊維とし、得られた該複合繊維の１成分を溶解除去することにより、極細繊維を得るものである。この方法は、非常に細い繊維を得ることができる反面、１成分を溶解除去するために非経済的である。一方、分割型複合繊維を用いる方法は、複数成分の樹脂を組み合せて紡糸して複合繊維とし、得られた該複合繊維を物理的応力や樹脂の化学薬品に対する収縮差などを利用して、該分割型複合繊維を多数の繊維に分割して極細繊維を得るものである。
【０００３】
例えば、ポリエステル樹脂とポリオレフィン樹脂の組み合せ、ポリエステル樹脂とポリアミド樹脂の組合せ、ポリアミド樹脂とポリオレフィン樹脂の組み合わせに代表される分割型複合繊維を極細細繊化し、不織布等に加工する際、高圧液体流処理等の分割細繊化工程が不織布化工程の律速段階となる。また分割細繊化に要するエネルギーコストも大きいといった問題があった。
【０００４】
一方、ポリオレフィン系樹脂同士、ポリエステル系樹脂同士、ポリアミド系樹脂同士などの同系樹脂の組み合せでは、前記異種ポリマーに比べて比較的樹脂の相溶性が良いため、前記のような問題がさらに大きくなり、分割細繊化させるためには、物理的衝撃をさらに大きくする必要がある。このため、得られた不織布は、分割された部分と分割されない部分が存在したり、繊維が物理的衝撃で動き、目付の厚い部分と薄い部分ができるなど、いわゆるむらが生じて地合が悪くなったり、また高圧液体流処理の加工速度を大幅に下げる必要があるなどの問題点があった。
【０００５】
この問題点を改善するために特開平４−２８９２２号公報では、オルガノシロキサン及びこれらの変性体を樹脂に添加することにより、同種ポリマー同士の組み合せの分割型複合繊維であっても容易に分割することができることが開示されている。しかしながら、分割性は多少向上するものの、分割された繊維を用いて得られた不織布は強力が低下したり、２次加工での加工性不良などの問題点があった。
【０００６】
【発明が解決しようとする課題】
本発明者らは、従来技術の有する問題点を解決するべく、鋭意検討を重ねた。その結果、少なくとも２成分の熱可塑性樹脂から構成された分割型複合繊維断面において、各成分は長軸方向に配列され、繊維断面の一方の片側表面は１成分により覆われており、紡糸工程における剥離防止、延伸工程や後処理工程での取り扱いに優れるため、細繊化が可能である。また、他方の片側表面は２成分が交互に表面に露出していることで分割性にも優れている。さらに該断面が屈曲、湾曲あるいは扁平形状の複合繊維であって、該断面の長軸Ｌと短軸Ｗの比（Ｌ／Ｗ）が３〜２０を満足した分割型複合繊維とすることで、より分割し易い分割型複合繊維となり、かつ、該分割型複合繊維を用いると緻密で地合の良い繊維成形体が得られることを見出し、この知見に基づいて本発明を完成するに至った。
以上の記述から明らかなように、本発明の目的は分割性を向上させるための添加剤を一切添加せずに、同系樹脂同士の組み合わせであっても、分割性に優れた分割型複合繊維を提供すると共に緻密で地合の良い繊維成形体及び該成形体を用いた製品を提供することである。
【０００７】
【問題を解決するための手段】
本発明は以下の構成を有する。
（１）少なくとも２成分の熱可塑性樹脂から構成された分割型複合繊維であって、繊維断面における各成分は長軸方向に配列され、繊維断面の一方の片側表面は１成分のみで覆われ、他方の片側表面は２成分が交互に表面に露出していることを特徴とする分割型複合繊維。
【０００８】
（２）分割型複合繊維の繊維断面が屈曲、湾曲もしくは扁平形状の複合繊維であって、該断面の長軸Ｌと短軸Ｗとの比（Ｌ／Ｗ）が３〜２０であることを特徴とする前記（１）項記載の分割型複合繊維。
【０００９】
（３）分割型複合繊維の繊維断面において、屈曲もしくは湾曲により囲まれた面積Ｓ１と該分割型複合繊維の断面積Ｓ２の比（Ｓ１／Ｓ２）が０．２〜１．０である前記（２）項記載の分割型複合繊維。
【００１０】
（４）繊維成形後の該繊維を構成する少なくとも２成分の熱可塑性樹脂のメルトフローレートがいずれも１０〜１００ｇ／１０分であり、かつ該熱可塑性樹脂のうち、融点が最も高い樹脂成分（以下、Ａ成分という）のメルトフローレート（ＭＦＲ−Ａ）と、融点が最も低い樹脂成分（以下、Ｂ成分という）のメルトフローレート（ＭＦＲ−Ｂ）との比（ＭＦＲ−Ａ／ＭＦＲ−Ｂ）が０．１〜５である前記（１）〜（３）項のいずれか１項記載の分割型複合繊維。
【００１１】
（５）分割型複合繊維の繊維断面において、繊維を構成するＢ成分の繊維外周面長ａと、隣接成分との接触長ｂとの比（ａ／ｂ）が０．１〜２．５である前記（１）〜（４）項のいずれか１項記載の分割型複合繊維。
【００１２】
（６）分割型複合繊維の繊維断面において、短軸Ｗと、Ｂ成分の繊維表面部までの厚みｃとの比（ｃ／Ｗ）が０．１〜０．５である前記（１）〜（５）項のいずれか１項記載の分割型複合繊維。
【００１３】
（７）少なくとも２成分の熱可塑性樹脂の組合せが、ポリプロピレン系樹脂、ポリエチレン系樹脂及びポリエステル系樹脂である前記（１）〜（６）項のいずれか１項記載の分割型複合繊維。
【００１４】
（８）分割型複合繊維の分割前の単糸繊度が０．５〜１０デシテックス、分割後の単糸繊度が０．５デシテックス以下である前記（１）〜（７）項のいずれか１項記載の分割型複合繊維。
【００１５】
（９）前記（１）〜（８）項のいずれか１項記載の分割型複合繊維を少なくとも３０重量％以上含み、かつ該分割型複合繊維の５０％以上が分割している繊維成形体。
【００１６】
（１０）繊維成形体が繊維集合体である前記（９）項記載の繊維成形体。
【００１７】
（１１）繊維成形体がスパンボンド法により得られる繊維集合体である前記（９）項もしくは前記（１０）項記載の繊維成形体。
【００１８】
（１２）前記（９）〜（１１）項のいずれか１項記載の繊維成形体の片面または両面に他のシートを積層してなる積層繊維成形体。
【００１９】
（１３）前記（９）〜（１１）項のいずれか１項記載の繊維成形体を他のシートの両面に積層してなる積層繊維成形体。
【００２０】
（１４）前記（１２）項もしくは前記（１３）項記載のシートが不織布、フィルム、編物、織物の少なくとも１種から選ばれた積層繊維成形体。
【００２１】
（１５）前記（９）〜（１４）項のいずれか１項記載の繊維成形体もしくは積層繊維成形体を用いた吸収性物品。
【００２２】
（１６）前記（９）〜（１４）項のいずれか１項記載の繊維成形体もしくは積層繊維成形体を用いたワイパー。
【００２３】
（１７）前記（９）〜（１４）のいずれか１項記載の繊維成形体もしくは積層繊維成形体を用いたバッテリーセパレーター。
【００２４】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の分割型複合繊維に用いる熱可塑性樹脂は、溶融紡糸工程で繊維成形性を有するものであれば特に限定されないが、例えばポリエステル系樹脂、ポリアミド系樹脂、ポリオレフィン系樹脂等を好適に使用される樹脂として挙げることができる。
【００２５】
ポリエステル系樹脂としては、酸成分としてテレフタル酸、イソフタル酸、フタル酸、２，６−ナフタレンジカルボン酸等の芳香族ジカルボン酸もしくはアジピン酸、セバシン酸などの脂肪族ジカルボン酸またはこれらのエステル類と、アルコール成分としてエチレングリコール、ジエチレングリコール、１，４−ブタンジオール、ネオペンチルグリコール、１，４−シクロヘキサンジメタノール等のジオール化合物とから合成された単独重合体ポリエステルないし共重合体ポリエステルであり、上記ポリエステルにパラオキシ安息香酸、５−ナトリウムスルフォイソフタール酸、ポリアルキレングリコール、ペンタエリスリトール等が添加もしくは共重合されているものも含まれる。
【００２６】
ポリアミド系重合体としては、６，６−ナイロン、６，１０−ナイロン、６−ナイロン、１，１−ナイロン、１，２−ナイロン、４−ナイロン、４，６−ナイロン及びこれらを主体とする共重合体等を例示することができる。
【００２７】
一方、ポリオレフィン系樹脂としては、炭素数が２〜８個の脂肪族α−オレフィン、例えばエチレン、プロピレン、１−ブテン、１−ペンテン、４−メチル−１−ペンテン、３−メチル−１−ブテン、１−ヘキセン、１−オクテン等の単独重合体又はこれらのα−オレフィンの２種以上の共重合体、前記α−オレフィンと他のオレフィン及び／または少量の他のエチレン系不飽和モノマー、例えばブタジエン、イソプレン、ペンタジエン−１、スチレン、α−メチルスチレン等のエチレン系不飽和モノマーとの共重合体及びこれらの２種以上の混合物を挙げることができる。
【００２８】
代表的なポリオレフィン系樹脂としては、ポリプロピレン系樹脂及びポリエチレン系樹脂を挙げることができ、該ポリプロピレン系樹脂としては、例えばプロピレン単独重合体、プロピレンを７０重量％以上含有するプロピレンとプロピレン以外の上記α−オレフィンとの共重合体、例えばエチレン−プロピレン共重合体、エチレン−プロピレン−ブテン共重合体等を挙げることができる。
【００２９】
また、ポリエチレン系樹脂としては、高密度ポリエチレン（ＨＤＰＥ）、低密度ポリエチレン（ＬＤＰＥ）、直鎖状低密度ポリエチレン（Ｌ−ＬＤＰＥ）等を挙げることができる。
【００３０】
熱可塑性樹脂のメルトフローレート（以下、ＭＦＲという場合あり）のうち、ポリプロピレン系樹脂のＭＦＲ（２３０℃、２．１８Ｎ）及びポリエチレン系樹脂のＭＦＲ（１９０℃、２．１８Ｎ）は、紡糸可能な範囲であれば特に限定されることはないが、１〜１００ｇ／１０分が好ましく、より好ましくは、５〜７０ｇ／１０分である。
【００３１】
前記以外の熱可塑性樹脂としては、例えばビニル系重合体が用いられ、具体的には、ポリビニルアルコール、ポリ酢酸ビニル、ポリアクリル酸エステル、エチレン酢酸ビニル共重合体、シンジオタクチックポリスチレンまたはこれらの共重合体を使用することができる。
【００３２】
本発明の分割型複合繊維は、前記の中、少なくとも２成分の熱可塑性樹脂を任意に組み合せることが可能であるが、衣料用途など染色が必要な分野では、例えば、ポリエステル系樹脂、ポリアミド系樹脂を主とした組み合わせが好適である。また耐薬品性、軽量性及びコストが要求される産業資材分野及び衛生材料分野等では、耐薬品性が高く、コスト的に有利なポリオレフィン系樹脂を主体とした組み合わせが例示でき、中でも耐薬品性が要求される分野には、ポリプロピレン系樹脂及びポリエチレン系樹脂の組み合わせが好適である。
【００３３】
ここで前記熱可塑性樹脂は任意の組み合わせが可能であるが、例えば、ポリエチレンテレフタレート樹脂とポリエチレンテレフタレート樹脂の組み合わせ、ポリプロピレン樹脂とポリプロピレン樹脂の組み合わせのような全く同一樹脂の組み合せ及び同一構成比を有する混合物の組み合せは本発明の範疇から除外される。
【００３４】
本発明の分割型複合繊維に好適に使用されるポリプロピレン系樹脂とポリエチレン系樹脂の２成分の組み合せにあっては、該ポリプロピレン系樹脂が融点が最も高い樹脂成分（高融点樹脂または、Ａ成分と略す場合あり）となる。かかるポリプロピレン系樹脂は具体的には、チーグラーナッタ触媒、メタロセン触媒等で重合されたシンジオタクチックポリプロピレン、アイソタクチックポリプロピレンが例示できる。また、本発明の分割型複合繊維を構成する少なくとも２成分の熱可塑性樹脂のうち、Ａ成分のＭＦＲをＭＦＲ−Ａとし、Ｂ成分のＭＦＲをＭＦＲ−Ｂとしたとき、Ａ成分である該ポリプロピレン系樹脂のＭＦＲ−Ａは、溶融紡糸可能な範囲であれば良く、紡糸条件等の変更で、繊維成形後のＭＦＲ−Ａが１０〜１００ｇ／１０分の範囲内であれば特に問題はない。繊維成形後のＭＦＲ−Ａは、より好ましくは、１０〜７０ｇ／１０分である。繊維成形後のＭＦＲ−Ａが１０ｇ／１０分未満、もしくは１００ｇ／１０分を超える場合は、可紡性良く、細い繊維に紡糸することが困難となる。
【００３５】
ポリエチレン系樹脂は、前記２成分の組み合わせにあっては、融点が最も低い樹脂成分（低融点樹脂またはＢ成分と略す場合あり）であって、具体的には、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例示することができる。また、これらポリエチレンの２種以上の混合物であっても良い。原料としてのポリエチレン系樹脂のＭＦＲ−Ｂは溶融紡糸可能な範囲であれば良く、紡糸条件等の変更で、繊維成形後のＭＦＲ−Ｂが１０〜１００ｇ／１０分の範囲内であれば特に問題はない。繊維成形後のＭＦＲ−Ｂは、より好ましくは、１０〜６０ｇ／１０分である。ＭＦＲ−Ｂが１ｇ／１０分未満、もしくは１００ｇ／１０分を超える場合は、可紡性良く、細い繊維に紡糸することが困難となる。
【００３６】
ＭＦＲの比（ＭＦＲ−Ａ／ＭＦＲ−Ｂ）は、０．１〜５であることが好ましく、さらに好ましくは、０．５〜３である。この値が０．１未満であったり、５を超える場合には、溶融紡糸時の２成分の口金内の流れ性、屈曲、湾曲、もしくは扁平形状に吐出された後の溶融張力差、冷却時の粘度上昇の差が大きくなるなどの要因上、曳糸性を維持することが困難となる。
【００３７】
本発明に使用する熱可塑性樹脂には、本発明の効果を妨げない範囲内でさらに、酸化防止剤、光安定剤、紫外線吸収剤、中和剤、造核剤、エポキシ安定剤、滑剤、抗菌剤、難燃剤、帯電防止材、顔料、可塑剤、親水剤などの添加剤を適宜必要に応じて添加しても良い。
【００３８】
次に本発明の分割型複合繊維の繊維断面について図面を用いて説明する。
本発明の分割型複合繊維は、例えば図１に例示したような少なくとも２成分の熱可塑性樹脂から構成され、繊維断面において、各成分は長軸方向に交互に配列され、かつ、該断面が屈曲、湾曲もしくは扁平形状の複合繊維であって、該断面の長軸Ｌと短軸Ｗの比（Ｌ／Ｗ）が３〜２０の分割型複合繊維である。ここで長軸Ｌとは、各成分が交互に隣接される方向で、かつ、断面形状の最も長い部分の長さを表す（図１参照）。短軸Ｗとは、各成分の接触面方向、即ち断面形状の厚みを表す（図１参照）。Ｌ／Ｗの比が３以上であると、通常の円断面分割型複合繊維、例えば放射状、積層状分割型複合繊維と比べて、分割セグメント数および繊度が同じである場合、表面積が大きく、また、隣接成分同士の接触面積は小さくなるため、高圧液体流を効果的に該複合繊維に受けることができ、同じ水圧であっても分割し易くなる。また、２０を超えると効果的に高圧液体流を複合繊維が受けることができるが、曳糸性の維持、口金の単位面積当たりの孔数が少なくなり、生産性が悪くなるなどの問題が発生する。
【００３９】
さらに、断面形状が屈曲、湾曲もしくは扁平形状をしていることでさらに分割性が向上する。繊維断面形状が直線であるもの（図１１参照）と比べて、製糸工程中、例えば紡糸工程で得られた未延伸糸を延伸工程で延伸する場合、速度差のあるロール間で集束された繊維は強い応力で延伸されるが、この時繊維同士は高い圧力で圧迫されることとなる。また短繊維とする場合には、カット工程で延伸工程と同等以上の強い圧力で繊維同士が圧迫されることとなる。このため、屈曲もしくは湾曲した繊維断面を有する本発明の分割型複合繊維は、直線状の断面形状と比べて、非常に潰され易く、即ち分割が部分的に進行することとなる。また分割しなくても該複合繊維の各成分の接触界面には歪みが加わり、本発明の分割型複合繊維は非常に分割し易くなる。
【００４０】
このように製糸工程中で、すでに部分的に分割が進行している場合は、抄紙法が好適に使用できる。抄紙法の場合、すでに部分的に分割が進行している方が抄紙の段階で緻密な地合の良いウェブとなり好ましい。また製糸工程中での分割の進行を極力抑えたい場合は、延伸倍率を低く設定することが有効である。具体的には、延伸糸伸度が未延伸糸伸度の２０％以上を有することが好ましい。ここで屈曲もしくは湾曲した断面形状は、特に限定されるものではなく、例えば、Ｃ型（図１〜５及び１０参照）、Ｓ字型（図７参照）、Ｍ字型、Ｎ字型、Ｌ字型、Ｖ字型、Ｗ型（図８参照）、中空型（図９参照）、波型などを挙げることができる。ただし、本発明はこれらの断面形状に限定されるものではない。また、種々の断面形状の混合物であっても良い。
さらに、偏平形状としては、例えばＵ型、馬蹄形型や該Ｕ型、馬蹄形型の湾曲部が圧縮されて偏平になった断面形状を挙げることができるが、本発明はこれらの断面形状に限定されるものではない。
【００４１】
前記のように本発明の分割型複合繊維の繊維断面形状は、長軸方向に屈曲、湾曲もしくは偏平形状しているため、延伸、カット工程と同様な効果をカレンダーロール同士の加圧によっても行うことができる。従って、例えばスパンボンド法のような未延伸糸状態の長繊維をそのままコンベアーに集積した場合であっても、加圧されたカレンダーロール間を通過させることにより、分割、細繊化された繊維集合体とすることができる。また従来のスパンボンド法で得られ、オムツなどの衛生材料に採用されている繊度は、約２．２ｄｔｅｘ前後が主流であるが、本発明の分割型複合繊維は繊維断面の一方の片側表面が１成分により覆われているため、相溶性の悪い樹脂の組み合わせにおいても、紡糸中の剥離等による可紡性悪化が起こらず、従来品と同等の繊度を得ることができる。
【００４２】
本発明の分割型複合繊維を構成する樹脂のＢ成分の繊維外周弧長ａ（繊維外周面長ａ）と、隣接成分との接触長ｂとの比（ａ／ｂ）は、０．１〜２．５を満足することが好ましい。該比（ａ／ｂ）が０．１未満であると、隣接成分との接触面積が繊維外周面に比べて大きくなり、薄片が積層した構造となり高分割率を達成するには、高エネルギーが必要となる。また、２．５を超えると分割数が少なくなるか、もしくは偏平形状の厚みが薄くなりすぎるため、可紡性良く生産することが非常に難しくなる。
【００４３】
さらに本発明の分割型複合繊維の繊維断面において、短軸Ｗと、Ｂ成分の繊維表面部までの厚みｃとの比（ｃ／Ｗ）が０．１〜０．５を満足することが好ましい。ここで短軸Ｗとは各成分の接触面方向、即ち断面形状の厚みを表す（図１参照）。厚みｃとは断面形状の厚み短軸ＷからＢ成分の接触長さｂを差し引いた値（Ｗ−ｂ）、即ちＡ成分に覆われているＢ成分の繊維表面部までの厚みを表す（図１参照）。該（ｃ／Ｗ）の比が０．１未満であると、紡糸工程中に隣接樹脂の剥離などにより、可紡性に問題がある。また、０．５を超えると紡糸工程中の可紡性は良好であるが、分割処理後の分割性が悪くなるなどの問題が発生する。
【００４４】
また、本発明の分割型複合繊維の繊維断面において、屈曲や湾曲により囲まれた面積Ｓ１と該分割型複合繊維の断面積Ｓ２（図６参照）の比（Ｓ１／Ｓ２）が０．２〜１．０を満足することが好ましい。ここでＳ１は、本発明の分割型複合繊維の繊維断面において、長軸の両端を結んだ直線と屈曲あるいは湾曲により囲まれた部分を表し、屈曲あるいは湾曲の度合いを表す。即ちＳ１が大きくなれば長軸が大きく屈曲あるいは湾曲することなる。該比（Ｓ１／Ｓ２）は、０．２以上を満足することが好ましい。０．２未満であると、屈曲や湾曲が小さく、前記、屈曲や湾曲による効果が小さくなる。また１．０を越えると該複合繊維の長軸が長くなりすぎるか、または厚みが極端に薄くなるなどの問題から生産性を維持することが困難となる。
【００４５】
本発明の分割型複合繊維は、前記のような繊維断面形状を取ることにより、従来の分割型複合繊維では、非常に分割し難く、分割させるために高エネルギーが必要であった同系樹脂の組み合わせ、特にポリオレフィン系樹脂同士の組み合わせであっても、分割性に優れ、容易に分割させることができる。また、ポリオレフィン系樹脂とポリエステル系樹脂の組み合わせのような、非相溶性であっても、繊維断面の一方の片側表面が樹脂により覆われていることで、紡糸工程における細繊化が可能であり、さらに後処理工程においての取り扱いが容易である。また、抄紙法で用いる短繊維で構成されたウェブであっても、地合良く高分割率で分割させることができる。以上のことから、本発明の分割型複合繊維は相溶性、非相溶性の色々な樹脂同士の組み合わせに用いることができる。ここで本発明の分割型複合繊維の繊維断面を得るために用いる紡糸用口金は、該分割複合繊維が得られるものであれば特に限定されることはないが、例えば、細孔がＣ型、Ｓ字型、Ｍ字型、Ｎ字型、Ｌ字型、Ｖ型、Ｗ型、波型、Ｕ型、馬蹄形型等に配置された口金を用いることができる。
【００４６】
本発明の分割型複合繊維において、少なくとも２成分の熱可塑性樹脂から構成される該複合繊維の複合比は、１０／９０〜９０／１０重量％の範囲でその用いた成分樹脂の合計が１００重量％であれば良く、より好ましくは３０／７０〜７０／３０重量％であり、最も好ましくは、４０／６０〜６０／４０重量％である。かかる範囲の複合比とすることにより、少なくとも２種類の熱可塑性樹脂が均一に配置された断面形状となり、より均一な繊維成形体とすることができる。
【００４７】
本発明で得られる分割型複合繊維を高圧液体流処理等で分割する場合、分割後の極細繊維の平均繊度は０．５デシテックス（ｄｔｅｘと記する場合あり）以下で、特に０．３デシテックス以下となることが好ましい。従って分割型複合繊維の分割セグメント数は、極細繊維の平均繊度が０．５デシテックス以下となるように決めれば良く、分割セグメント数が多ければ分割後の繊度が小さくなる利点があるが、実際には繊維製造上の容易さから４〜３２セグメント数とすることが好ましい。
【００４８】
分割前の単糸繊度は、特に限定されることはないが、０．５〜１０．０デシテックスであることが好ましく、より好ましくは、１．０〜６．０デシテックスである。また個々のセグメントの繊度は同一である必要はなく、分割型複合繊維が完全に分割していない場合には、未分割の分割繊維と完全に分割した極細繊維との中間に複数の異なった繊度の繊維が混在していても良い。
【００４９】
以下、本発明の分割型複合繊維の１例として、ポリプロピレン樹脂と高密度ポリエチレン樹脂の２成分を組み合わせた分割複合繊維の製造方法を例示する。
通常の溶融紡糸機を用いて前記樹脂からなる長繊維を紡出する。紡糸に際し、紡糸温度は２００〜３３０℃の範囲で紡糸することが好ましく、引き取り速度は４０ｍ／分〜１５００ｍ／分程度とするのが良い。延伸は必要に応じて行っても良く、延伸を行う場合、延伸倍率は通常３〜９倍程度とするのが良い。さらに得られたトウは所定長に切断して短繊維とする。以上は短繊維の製造工程を開示したが、トウを切断せず、長繊維トウを分繊ガイドなどによりウェブとすることもできる。その後は必要に応じて高次加工工程を経て、種々、用途に応じて繊維成形体に形成される。また、紡糸延伸後、フィラメント糸等として巻き取り、これを編成または織成して編織物とした繊維成形体あるいは前記短繊維を紡績糸とした後、これを編成または織成して編織物とした繊維成形体に形成しても良い。
【００５０】
つまり、ここで繊維成形体とは、布状の形態であればいかなるものでも良く、例えば織物、編物、不織布あるいは不織繊維集合体などが挙げられる。また、混綿、混紡、混繊、交撚、交編、交繊等の方法で布状の形態にしたものも含まれる。さらに不織繊維集合体とは、例えばカード法、エアレイド法、もしくは抄紙法などの方法で均一にしたウェブ状物あるいはこのウェブ状物に織物、編物、不織布を種々積層したものなどをいう。
【００５１】
かかる工程において、繊維を紡出後、繊維の静電気防止、繊維成形体への加工性向上のための平滑性付与などを目的として界面活性剤を繊維表面に付着させることができる。界面活性剤の種類、濃度は用途に合わせて適宜調整する。付着の方法は、ローラ法、浸漬法、パットドライ法などを用いることができる。付着は、紡糸工程、延伸工程、捲縮工程のいずれで付着させても差し支えない。さらに短繊維、長繊維に問わず、紡糸工程、延伸工程、捲縮工程以外の、例えば繊維成形体に成形後、界面活性剤を付着させることもできる。
【００５２】
本発明の分割型複合繊維の繊維長は、特に限定されるものではないが、カード機を用いてウェブを作成する場合は、一般に２０〜７６ｍｍのものを用い、抄紙法やエアレイド法では、一般に繊維長が２ｍｍ〜２０ｍｍのものが好ましく用いられる。繊維長が２ｍｍ未満の場合には、物理的衝撃で繊維が動いてしまい、分割に必要なエネルギーを繊維自体が受けにくくなってしまう。また、繊維長が７６ｍｍを大幅に超える場合はカード機等でのウェブ形成が均一にできず、均一な地合のウェブとするのが難しくなる。
【００５３】
本発明の分割型複合繊維からなる繊維成形体の製造方法の一例として、不織布の製造方法を例示する。例えば前記分割型複合繊維製造方法で製造された短繊維を用いて、カード法、エアレイド法、あるいは抄紙法を用いて必要な目付のウェブを作製する。またメルトブロー法、スパンボンド法などで直接ウェブを作製しても良い。前記の方法で作製したウェブを、ニードルパンチ法、高圧液体流処理、加圧されたカレンダーロール等の公知の方法で分割細繊化して繊維成形体を得ることができる。さらに繊維成形体を熱風あるいは熱ロール等の公知の加工方法で処理することもできる。抄紙法などの非常に短い繊維で構成されたウェブをニードルパンチ法、高圧液体流処理等の公知の方法で分割細繊化する場合に、その物理的応力で繊維が分割すると同時に繊維が動いて地合不良となる場合があるため、予め本発明の分割型複合繊維を構成する樹脂の融点よりも低融点で熱融着する繊維を５〜３０重量％混綿しておき、この低融点繊維が融着する温度で熱処理を行い、熱融着された不織布を作成しておくことで地合不良を抑えることができる。
【００５４】
本発明の繊維成形体の目付は、特に限定されるものではないが、１０〜２００ｇ／ｍ²のものが好ましい。目付が１０ｇ／ｍ²未満では、該不織布を製造するために、分割型複合繊維を高圧液体流処理などの物理的応力で分割、細繊化すると、地合不良な不織布となる場合がある。また目付が２００ｇ／ｍ²を超えると、目付が高く、高圧水流が必要となり、地合良く、均一な分割を行うことが困難となる場合がある。
【００５５】
本発明の繊維成形体は、本発明の妨げにならない範囲で、必要に応じて本発明の分割型複合繊維に他の繊維を混合して用いることができる。かかる他の繊維としては、ポリアミド、ポリエステル、ポリオレフィン、アクリルなどの合成繊維、綿、羊毛、麻などの天然繊維、レーヨン、キュプラ、アセテートなどの再生繊維、半合成繊維などが挙げられる。
【００５６】
次に、高圧液体流処理について説明する。高圧液体流処理に用いる高圧液体流装置としては、例えば、孔径が０．０５〜１．５ｍｍ、特に０．１〜０．５ｍｍの噴射孔を孔間隔０．１〜１．５ｍｍで一列あるいは複数列に多数配列した装置を用いる。噴射孔から高水圧で噴射させて得られる高圧液体流を多孔性支持部材上に置いた前記ウェブに衝突させる。これにより本発明の未分割の分割型複合繊維は高圧液体流により、交絡されると同時に細繊化される。噴射孔の配列は前記ウェブの進行方向と直交する方向に列状に配列する。高圧液体流としては、常温あるいは温水を用いても良し、任意に他の液体を用いても良い。
【００５７】
噴射孔とウェブとの間の距離は、１０〜１５０ｍｍとするのが良い。この距離が１０ｍｍ未満であるとこの処理により得られる繊維成形体の地合が乱れ、一方、この距離が１５０ｍｍを超えると液体流がウェブに与える物理的衝撃が弱くなり、交絡及び分割細繊化が十分に施されない場合がある。この高圧液体流の処理圧力は、製造方法及び繊維成形体の要求性能によって、制御されるが、一般的には、２〜２０ＭＰａの高圧液体流を噴射するのが良い。なお処理する目付等にも左右されるが、前記処理圧力の範囲内において、高圧液体流は順次、低水圧から高水圧へ圧力を上げて処理すると、ウェブの地合が乱れることなく、交絡及び分割細繊化が可能となる。高圧液体流を施す際にウェブを載せる多孔性支持部材としては、例えば５０〜２００メッシュの金網製あるいは合成樹脂製のメッシュスクリーンや有孔板など高圧液体流が上記ウェブを貫通するものであれば特に限定されない。
【００５８】
尚、ウェブの片面より高圧液体流処理を施した後、引き続き交絡処理されたウェブを反転させて、高圧液体流処理を施すことによって、表裏共に緻密で地合の良い繊維成形体を得ることができる。さらに高圧液体流処理を施した後、処理後の繊維成形体から水分を除去する。この水分を除去するに際しては、公知の方法を採用することができる。例えば，マングロール等の絞り装置を用いて、水分をある程度除去した後、熱風循環式乾燥機等の乾燥装置を用いて完全に水分を除去して本発明の繊維成形体を得ることができる。
【００５９】
前記の方法で本発明の分割型複合繊維を含むウェブに高圧液体流処理を施して分割細繊化し、緻密な繊維成形体を得るに際し、従来の繊維断面を有する分割型複合繊維（図１２）に比べ、易分割し易く、高圧液体流による物理的衝撃が少なくて済む。このため、不織布加工工程の律速段階である高圧液体流処理の高速化及び高圧液体流の低圧化による地合の改善、例えば高圧液体流の圧力を低くできるため、繊維成形体の地合が乱れたり、貫通孔が開くなどの問題を改善することができる。
【００６０】
以上のように最も分割し難いとされていた同系樹脂から構成された分割型複合繊維であっても、容易に分割させることができ、緻密で地合の良い繊維成形体を得ることができる。これにより、バッテリセパレーターやワイパー等の産業資材分野をはじめ、衛生材料分野、衣料分野にも好適に使用することができる。
【００６１】
さらに、本発明の繊維成形体の片面もしくは両面に不織布、フィルム、編物、織物等から選ばれた少なくとも１種からなるシートを積層した、積層繊維成形体（以下αタイプ）や、さらには該繊維成形体を逆に前記シートの両面に積層した積層繊維成形体（以下βタイプ）とすることができる。
αタイプの場合は分割処理した繊維成形体をシートの片面もしくは両面に積層する方が分割効率は良く、好ましい。βタイプの場合は積層前後、どちらでも繊維成形体は分割されるが、特に積層後の分割処理はシートと繊維成形体との絡合作用が得られ好ましい。これらの積層繊維成形体（αタイプ）、（βタイプ）のいずれもオムツ、ナプキン等の吸収性物品で代表される衛生材料分野、ワイパー、バッテリセパレーター等の産業資材分野にも好適に使用することができる。
【００６２】
【実施例】
以下、本発明を実施例及び比較例によって詳細に説明するが、本発明はこれにより限定されるものではない。なお実施例、比較例における用語と物性の測定方法は以下の通りである。
【００６３】
（１）メルトフローレート：ＪＩＳＫ７２１０に準拠して測定した。
原料ポリプロピレン樹脂：条件１４
原料ポリエチレン樹脂：条件４
繊維成形後のポリオレフィン系樹脂：条件１４
【００６４】
（２）Ｌ／Ｗ測定法
任意に選んだ未分割繊維１０本の断面写真から、以下の値を計算し、その平均値からＬ／Ｗを算出した。
Ｌ：各成分が交互に隣接される方向で、かつ、繊維断面形状のもっとも長い部分を表す（図１参照）
Ｗ：各成分の接触面方向、即ち断面形状の厚みを表す（図１参照）
【００６５】
（３）ａ／ｂ測定法
任意に選んだ未分割繊維１０本の断面写真から、以下の値を計算し、その平均値からａ／ｂを算出した。
ａ：１成分の繊維外周面長の平均値（図１参照）
ｂ：１成分の接触長の平均値（図１参照）
【００６６】
ｃ／Ｗ測定法
任意に選んだ未分割繊維１０本の断面写真から、以下の値を計算し、その平均値からｃ／Ｗを算出した。
ｃ：（Ｗ−ｂ）（図１参照）
Ｗ：各成分の接触面方向、即ち断面形状の厚みを表す（図１参照）
【００６７】
（５）Ｓ１／Ｓ２測定法
任意に選んだ未分割繊維１０本の繊維断面写真から、Ｓ１、Ｓ２の面積を計算し、その平均値からＳ１／Ｓ２を算出した（図６参照）
Ｓ１：長軸の両端を結んだ直線と屈曲もしくは湾曲により囲まれた部分の面積
Ｓ２：本発明の分割型複合繊維の断面積
【００６８】
（６）曳糸性
溶融紡糸時の曳糸性を糸切れ回数の発生率により、次の３段階で評価した。
○：糸切れが全く発生せず、操作性が良好である。
△：糸切れが１時間当たり１〜２回
×：糸切れが１時間当たり４回以上発生し、操作上問題がある。
【００６９】
（７）延伸倍率
以下の式により算出した。
延伸倍率＝引取ロール速度（ｍ／分）／供給ロール（ｍ／分）
【００７０】
（８）繊維引張強伸度
ＪＩＳ−Ｌ１０１３法に準じ、島津製作所（株）製オートグラフＡＧＳ５００Ｄを用い、糸長１００ｍｍ、引張速度１００ｍｍ／分で測定した。
【００７１】
（９）不織布の引張強伸度
５ｃｍ幅の不織布を島津製作所（株）製オートグラフＡＧＳ５００Ｄを用い、ＭＤ方向の不織布破断強度を測定した。試長１００ｍｍ、引張速度２００ｍｍ／分で測定し、測定温度は室温とした。
【００７２】
（１０）分割率の測定
分割後の不織布をワックスにて包含し、ミクロトームで繊維軸に対して、直角にスライスして資料片を作成する。これを顕微鏡で観察し、繊維の断面像を画像処理して、セグメントの７０％以上が分割された繊維の総断面積（Ａ）と未分割繊維の総断面積（Ｂ）を測定し、以下の式で算出した。
分割率（％）＝｛Ａ／（Ａ＋Ｂ）｝×１００
【００７３】
（１１）分割後の単糸繊度
分割前の繊度と分割可能なセグメント数から、分割細繊化後の単糸繊度を以下の式より算出した。
分割後繊度（ｄｔｅｘ／ｆ）＝分割前繊度（ｄｔｅｘ／ｆ）／分割可能セグメント数（個）
【００７４】
（１２）地合
１０人のパネラーが、分割細繊化加工後の不織布（１ｍ角）の繊維分布斑を目視した結果により次のように評価した。
○：７人以上が、斑が少なく、また貫通孔もないと感じた。
△：４〜６人が、斑が少なく、貫通孔もないと感じた。
×：斑が少ないと感じたのは３人以下であった。
【００７５】
（１３）高圧液体流処理
ローラカード機、エアレイド機、抄紙機等で作製したウェブを８０メッシュの平織りからなるコンベアーベルト上に載せ、コンベアーベルト速度２０ｍ／分の速度で、ノズル径０．１ｍｍ、ノズルピッチ１ｍｍのノズル直下を通過させ、高圧液体流を噴射した。まず、２ＭＰａで予め予備処理（２段）した後、水圧５ＭＰａの高圧液体流で４段処理した。ウェブを反転させ、さらに水圧５ＭＰａの高圧液体流で４段処理することにより、分割細繊化した不織布を得た。ここで段とは、ノズル直下を通過した回数のことである。
【００７６】
（１４）加圧（分割）ロール
誘導発熱油圧式２本ロールクリアランス機（由里ロール（株）社製）
処理温度：雰囲気温度
処理線圧：４０Ｎ／ｍｍ
処理速度：１０ｍ／分
【００７７】
（１５）耐水圧
ＪＩＳＬ１０９２に準拠して測定した。
【００７８】
実施例１〜３
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（プロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、単糸繊度７．５ｄｔｅｘの図１に示した繊維断面形状を有する分割型複合繊維を紡糸した。引き取り工程において、アルキルフォスフェートカリウム塩を付着させた。得られた未延伸糸を９０℃、４．１倍で延伸し、抄紙用仕上げ剤を付着させた後、１０ｍｍに切断し、水分率２０重量％の短繊維を得た。
この短繊維にポリプロピレン（芯）／低密度ポリエチレン（鞘）の鞘芯複合繊維（ＥＡＣ繊維、チッソ（株））を２０重量％添加し、角型シートマシン（２５ｃｍ×２５ｃｍ）を用い、抄紙法でウェブとした。熊谷理器工業社製ヤンキードライヤーを用い、１０５℃で３分間乾燥、予備接着を行いウェブを得た。このウェブに前記高圧液体流処理を行った後、さらに８０℃のドライヤーで乾燥させて繊維成形体を得た。
【００７９】
実施例４
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（ポリプロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、単糸繊度７．５ｄｔｅｘの図２に示した繊維断面形状を有する分割型複合繊維を紡糸した。引き取り工程において、アルキルフォスフェートカリウム塩を付着させた。得られた未延伸糸を９０℃、１．５倍で延伸し、捲縮を付与し、５１ｍｍに切断した。
得られた短繊維をローラカード機にてウェブとし、該ウェブに前記高圧液体流処理を行った後、さらに８０℃のドライヤーで乾燥させて繊維成形体を得た。該繊維成形体を大人用オムツの表面材として使用したところ、肌触り（ソフト感）、不織布強力等に優れ、吸収性物品として非常に良好なものであった。
【００８０】
実施例５
図３に示した繊維横断面を得るための分割型複合繊維用口金を用いた以外は、実施例１に準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。
【００８１】
実施例６
高密度ポリエチレンの替わりに線状低密度ポリエチレンを用いた以外は、実施例１と準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。
【００８２】
実施例７
高密度ポリエチレンの替わりに低密度ポリエチレンを用いた以外は、実施例１に準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。
【００８３】
実施例８
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（ポリプロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、単糸繊度２０．０ｄｔｅｘの図１に示した繊維断面形状を有する分割型複合繊維を紡糸した。引き取り工程において、アルキルフォスフェートカリウム塩を付着させた。得られた未延伸糸を９０℃、４．１倍で延伸し、抄紙用仕上げ剤を付着させた後、１０ｍｍに切断し、水分率２０重量％の短繊維を得た。この短繊維にポリプロピレン（芯）／低密度ポリエチレン（鞘）の鞘芯複合繊維（ＥＡＣ繊維、チッソ（株））を２０重量％添加し、角型シートマシン（２５ｃｍ×２５ｃｍ）を用い、抄紙法でウェブとした。熊谷理器工業社製ヤンキードライヤーを用い、１０５℃で３分間乾燥、予備接着を行いウェブを得た。該ウェブに前記高圧液体流処理を行った後、さらに８０℃のドライヤーで乾燥させ繊維成形体を得た。
【００８４】
実施例９
図２に示した繊維横断面を得るための分割型複合繊維用口金を用いた以外は、実施例８に準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。
【００８５】
実施例１〜９の紡糸条件、繊維物性、形状、不織布物性、分割率等を後述の表１に示した。
【００８６】
実施例１０
相対粘度（フェノールと四塩化エタンとの等量混合物を溶媒とし、２０℃で測定した）０．６０のＰＥＴ（鐘紡（株）製、Ｋ１０１）を高融点樹脂（Ａ成分）とし、低融点樹脂（Ｂ成分）としてポリプロピレン樹脂（ＭＦＲ：１６ｇ／１０分のプロピレン単独重合体）を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、単糸繊度１５．０ｄｔｅｘの図１に示した繊維断面形状を有する分割型複合繊維を紡糸した。引き取り工程において、アルキルフォスフェートカリウム塩を付着させた。得られた未延伸糸を９０℃、３．３倍で延伸し、抄紙用仕上げ剤を付着させた後、１０ｍｍに切断し、水分率２０重量％の短繊維を得た。この短繊維にポリプロピレン（芯）／低密度ポリエチレン（鞘）の鞘芯複合繊維（ＥＡＣ繊維、チッソ（株））を２０重量％添加し、角型シートマシン（２５ｃｍ×２５ｃｍ）を用い、抄紙法でウェブとした。熊谷理器工業社製ヤンキードライヤーを用い、１０５℃で３分間乾燥、予備接着を行いウェブを得た。該ウェブに前記高圧液体流処理を行った後、さらに８０℃のドライヤーで乾燥させ繊維成形体を得た。
【００８７】
実施例１１
図４に示した繊維断面を得るための分割型複合繊維用口金を用いた以外は、実施例１に準拠して分割型複合繊維の紡糸、繊維成形体の作製を行った。
【００８８】
実施例１２
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（ポリプロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、単糸繊度７．５ｄｔｅｘの図１に示した繊維断面形状を有する分割型複合繊維を紡糸した。引き取り工程において、アルキルフォスフェートカリウム塩を付着させた。得られた未延伸糸を９０℃、４．１倍で延伸し、抄紙用仕上げ剤を付着させた後１０ｍｍに切断し、水分率２０重量％の短繊維を得た。この短繊維にポリプロピレン（芯）／低密度ポリエチレン（鞘）の鞘芯複合繊維（ＥＡＣ繊維、チッソ（株））を２０重量％添加し、角型シートマシン（２５ｃｍ×２５ｃｍ）を用い、抄紙法でウェブとした。該ウェブを熊谷理器工業社製ヤンキードライヤーを用い、１０５℃で３分間乾燥、予備接着を行いウェブを得た。該ウェブに前記高圧液体流処理を行った後、さらに８０℃のドライヤーで乾燥させて繊維成形体を得た。
【００８９】
実施例１３
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（プロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、図１に示した繊維断面形状を有する分割型複合繊維をスパンボンド法にて紡糸した。紡糸口金より吐出した複合繊維群をエアーサッカーに導入して牽引延伸し、単糸繊度２．０ｄｔｅｘの複合長繊維を得、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ヤー上に、長繊維ウェブとして捕集する。該長繊維ウェブを加圧ロールで分割処理した後、１２０℃に加熱した面積率１５％のエンボスロール機にて処理し、繊維成形体を得た。
【００９０】
実施例１０〜１３の紡糸条件、繊維物性、形状、不織布物性、分割率等を後述の表２示した。
【００９１】
実施例１４
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（ポリプロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、単糸繊度７．５ｄｔｅｘの図１０に示した繊維断面形状を有する分割型複合繊維を紡糸した。引き取り工程において、アルキルフォスフェートカリウム塩を付着させた。得られた未延伸糸を９０℃、４．１倍で延伸し、抄紙用仕上げ剤を付着させた後、１０ｍｍに切断し、水分率２０重量％の短繊維を得た。この短繊維にポリプロピレン（芯）／低密度ポリエチレン（鞘）の鞘芯複合繊維（ＥＡＣ繊維、チッソ（株））を２０重量％添加し、角型シートマシン（２５ｃｍ×２５ｃｍ）を用い、抄紙法でウェブとした。これを、熊谷理器工業社製ヤンキードライヤーを用い、１０５℃で３分間乾燥、予備接着を行いウェブを得た。該ウェブに前記高圧液体流処理を行った後、さらに８０℃のドライヤーで乾燥させて繊維成形体を得た。紡糸条件、繊維物性、形状、不織布物性、分割率等を後述の表２に示した。
【００９２】
実施例１５
図１１に示した繊維断面を得るための分割型複合繊維用口金を用いた以外は、実施例１に準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。紡糸条件、繊維物性、形状、不織布物性、分割率等を後述の表２に示した。
【００９３】
比較例１
図１２に示した繊維断面を得るための分割型複合繊維用口金を用いた以外は、実施例１に準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。紡糸条件、繊維物性、形状、不織布物性、分割率等を後述の表２に示した。
【００９４】
比較例２
図１２に示した繊維断面を得るための分割型複合繊維用口金を用いた以外は、実施例１３に準拠して、分割型複合繊維の紡糸、繊維成形体の作製を行った。紡糸条件、繊維物性、形状、不織布物性、分割率等を後述の表２に示した。
【００９５】
実施例１６、１７
実施例１に準拠して繊維成形体を得る前工程（高圧液体流処理前）の目付１０ｇ／ｍ²のウェブ（ウェブＡと略す）を得た。次にポリプロピレン（芯）／高密度ポリエチレン（鞘）の鞘芯複合繊維（ＥＳＣ繊維、チッソ（株））２．２ｄｔｅｘ×５１ｍｍの短繊維を用い、目付１０ｇ／ｍ²のカードウェブ（ウェブＢと略す）を得た。ウェブＡを上層、ウェブＢを下層に積層したもの（実施例１６）及びウェブＡを上下層、ウェブＢを中層に積層したもの（実施例１７）を各々、前記高圧液体流処理を行った後、８０℃のドライヤーで乾燥させ繊維成形体を得た。さらに、この繊維成形体を拭き取り用ワイパーに使用したところ、実施例１６及び１７ともに非常に優れた拭き取り性を示した。
【００９６】
実施例１８
高融点樹脂（Ａ成分）としてポリプロピレン樹脂（ポリプロピレン単独重合体）、低融点樹脂（Ｂ成分）として高密度ポリエチレン樹脂を用い、分割型複合繊維用口金を用いて、Ａ成分及びＢ成分の両樹脂の容積比率を５０／５０とし、図１に示した繊維断面形状を有する分割型複合繊維をスパンボンド法で紡糸して、単糸繊度２．０ｄｔｅｘを得、中層用の目付１０ｇ／ｍ²のウェブを得た。次に、該樹脂の組み合わせにおいて、鞘芯型複合繊維用口金を用いて、Ａ成分を芯側、Ｂ成分を鞘側として、Ａ及びＢの両樹脂の容積比率を５０／５０とし、単糸繊度２．０ｄｔｅｘの複合繊維をスパンボンド法で紡糸して、目付５．０ｇ／ｍ²のウェブを得、該ウェブを上下層として上記中層用のウェブに積層し、加圧ロールで分割処理した後、１２０℃に加熱した面積率１５％のエンボス機にて処理し、積層繊維成形体を得た。さらに、該積層繊維成形体を大人用オムツの表面材として使用したところ、耐水圧、不織布強力等に優れ、吸収性物品として非常に良好なものであった。
【００９７】
【表１】

【００９８】
【表２】

【００９９】
表１、表２から明らかなように、本発明の実施例各例で得られた繊維成形体及び積層繊維成形体は、比較各例と比べて同条件でも高分割率で分割している。即ち、従来のような高水圧の高圧液体流処理を行わなくても、分割、細繊化が容易に進行するため、比較的低目付の不織布でも地合が乱れることなく製造することができ、さらに高圧液体流処理のコストも大幅に削減することができる。
【０１００】
【発明の効果】
本発明の分割型複合繊維は、非常に分割し易いため、特別に易分割させるための添加剤を一切添加せずに、物理衝撃を大きくしなくても極細繊維化が容易に行える。このため、本発明の分割型複合繊維を用いると緻密で地合いの良い繊維成形体が得られる。
【図面の簡単な説明】
【図１】本発明に用いられる分割型複合繊維の繊維断面の１模式図
【図２】本発明に用いられる分割型複合繊維の繊維断面の１模式図
【図３】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図４】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図５】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図６】屈曲もしくは湾曲により囲まれた面積（Ｓ１）と分割型複合繊維の断面積（Ｓ２）を示した模式図
【図７】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図８】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図９】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図１０】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図１１】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図１２】比較例に用いられる分割型複合繊維の繊維横断面の１模式図
【符号の説明】
Ｌ：複合繊維の各成分が交互に隣接される方向で、かつ、断面形状の最も長い部分の長さを表す。
Ｗ：複合繊維の各成分の接触面方向で断面形状の厚みを表す。
ａ：複合繊維を構成するＢ成分の繊維外周面長を表す。
ｂ：複合繊維を構成するＢ成分の隣接成分との接触長を表す。
ｃ：複合繊維を構成するＢ成分の接触長ｂを断面形状の厚みＷから差し引いた長さを表す。
Ｓ１：長軸の両端を結んだ直線と屈曲あるいは湾曲により囲まれた部分の面積を表す。
Ｓ２：複合繊維の繊維横断面積を表す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a split type composite fiber excellent in splitting property. More specifically, a split-type composite fiber having excellent splitting properties and a fiber using the same, which can be suitably used in the field of industrial materials such as battery separators, wipers and filters, sanitary materials such as diapers and napkins, and clothing. The present invention relates to a molded body and a laminated fiber molded body.
[0002]
[Prior art]
Conventionally, sea-island type and split type composite fibers are known as methods for obtaining ultrafine fibers. In the method using the sea-island type composite fiber, a combination of a plurality of components is spun to form a sea-island type composite fiber, and one component of the obtained composite fiber is dissolved and removed to obtain ultrafine fibers. Although this method can obtain very fine fibers, it is uneconomical for dissolving and removing one component. On the other hand, the method using a split-type composite fiber is a composite fiber obtained by spinning a combination of a plurality of components, and the resulting composite fiber is utilized by utilizing physical stress or a difference in shrinkage of the resin with respect to chemicals. A split type composite fiber is divided into a large number of fibers to obtain ultrafine fibers.
[0003]
For example, when a split type composite fiber represented by a combination of a polyester resin and a polyolefin resin, a combination of a polyester resin and a polyamide resin, or a combination of a polyamide resin and a polyolefin resin is made into a fine fiber and processed into a non-woven fabric, etc., a high-pressure liquid flow treatment The division finening process such as the above becomes the rate-limiting step of the non-woven fabric process. In addition, there is a problem in that the energy cost required for splitting and finening is large.
[0004]
On the other hand, in a combination of similar resins such as polyolefin resins, polyester resins, polyamide resins, and the like, since the compatibility of the resin is relatively good compared to the different polymers, the above-described problems are further increased. It is necessary to further increase the physical impact in order to divide into fine pieces. For this reason, the obtained nonwoven fabric has a divided portion and a portion that is not divided, or the fibers move due to physical impact, so that a thick portion and a thin portion are formed. And there is a problem that it is necessary to significantly reduce the processing speed of the high-pressure liquid flow treatment.
[0005]
In order to remedy this problem, Japanese Patent Laid-Open No. 4-28922 discloses that by adding organosiloxane and a modified product thereof to a resin, even a split type composite fiber of a combination of the same kind of polymers can be easily split. It is disclosed that it is possible. However, although the splitting property is somewhat improved, the nonwoven fabric obtained using the split fibers has problems such as reduced strength and poor workability in secondary processing.
[0006]
[Problems to be solved by the invention]
The inventors of the present invention have made extensive studies in order to solve the problems of the prior art. As a result, in the split-type composite fiber cross section composed of at least two components of the thermoplastic resin, each component is arranged in the major axis direction, and one surface of one side of the fiber cross section is covered with one component. Since it is excellent in prevention of peeling, handling in the stretching process and post-processing process, it can be made finer. Moreover, the other one-side surface is excellent in splitting property because two components are alternately exposed on the surface. Furthermore, the section is a composite fiber having a bent, curved or flat shape, and the ratio of the major axis L to the minor axis W (L / W) of the section is a split-type conjugate fiber satisfying 3 to 20, It became a split-type conjugate fiber that is easier to split, and when the split-type conjugate fiber was used, it was found that a dense and well-formed fiber molded body was obtained, and the present invention was completed based on this finding.
As is clear from the above description, the purpose of the present invention is to add a split type composite fiber having excellent splitting ability even if it is a combination of similar resins without adding any additive for improving splitting ability. It is to provide a dense and well-formed fiber molded body and a product using the molded body.
[0007]
[Means for solving problems]
The present invention has the following configuration.
(1) A split-type conjugate fiber composed of at least two component thermoplastic resins, each component in the fiber cross section being arranged in the major axis direction, one surface of one side of the fiber cross section being covered with only one component, A split-type composite fiber characterized in that two components are alternately exposed on the surface of the other side.
[0008]
(2) The fiber section of the split-type composite fiber is a composite fiber having a bent, curved or flat shape, and the ratio (L / W) of the major axis L to the minor axis W of the cross section is 3-20. The split type composite fiber according to item (1), characterized in that it is characterized in that
[0009]
(3) In the fiber cross section of the split-type conjugate fiber, the ratio (S1 / S2) of the area S1 surrounded by bending or bending to the cross-sectional area S2 of the split-type conjugate fiber is 0.2 to 1.0 ( The split type composite fiber according to item 2).
[0010]
(4) The resin component having the highest melting point among the thermoplastic resins, in which the melt flow rate of at least two thermoplastic resins constituting the fiber after fiber molding is 10 to 100 g / 10 min. Hereinafter, the ratio (MFR-A / MFR-B) between the melt flow rate (MFR-A) of the component A) and the melt flow rate (MFR-B) of the resin component having the lowest melting point (hereinafter referred to as component B). ) Is 0.1-5, The split type composite fiber according to any one of the above items (1) to (3).
[0011]
(5) In the fiber cross section of the split-type composite fiber, the ratio (a / b) between the fiber outer peripheral surface length a of the B component constituting the fiber and the contact length b of the adjacent component is 0.1 to 2.5. The split type composite fiber according to any one of (1) to (4).
[0012]
(6) In the fiber cross section of the split type composite fiber, the ratio (c / W) between the minor axis W and the thickness c to the fiber surface portion of the B component is 0.1 to 0.5. The split type composite fiber according to any one of (5).
[0013]
(7) The split-type conjugate fiber according to any one of (1) to (6), wherein the combination of at least two thermoplastic resins is a polypropylene resin, a polyethylene resin, and a polyester resin.
[0014]
(8) The single yarn fineness before splitting of the split-type composite fiber is 0.5 to 10 dtex, and the single yarn fineness after splitting is 0.5 dtex or less, any one of the above items (1) to (7) The split type composite fiber as described.
[0015]
(9) A fiber molded body comprising at least 30% by weight or more of the split-type conjugate fiber according to any one of (1) to (8) above, and 50% or more of the split-type conjugate fiber being split.
[0016]
(10) The fiber molded body according to (9), wherein the fiber molded body is a fiber assembly.
[0017]
(11) The fiber molded body according to (9) or (10) above, wherein the fiber molded body is a fiber assembly obtained by a spunbond method.
[0018]
(12) A laminated fiber molded body obtained by laminating another sheet on one side or both sides of the fiber molded body according to any one of (9) to (11).
[0019]
(13) A laminated fiber molded body obtained by laminating the fiber molded body according to any one of (9) to (11) on both surfaces of another sheet.
[0020]
(14) A laminated fiber molded body in which the sheet according to (12) or (13) is selected from at least one of a nonwoven fabric, a film, a knitted fabric, and a woven fabric.
[0021]
(15) An absorbent article using the fiber molded body or laminated fiber molded body according to any one of (9) to (14).
[0022]
(16) A wiper using the fiber molded body or laminated fiber molded body according to any one of (9) to (14).
[0023]
(17) A battery separator using the fiber molded body or laminated fiber molded body according to any one of (9) to (14).
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The thermoplastic resin used for the split composite fiber of the present invention is not particularly limited as long as it has fiber formability in the melt spinning process. For example, polyester resins, polyamide resins, polyolefin resins and the like are preferably used. It can be mentioned as a resin.
[0025]
Examples of the polyester resin include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid or aliphatic dicarboxylic acids such as adipic acid and sebacic acid as esters, and esters thereof. A homopolymer polyester or copolymer polyester synthesized from a diol compound such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol as an alcohol component. Those having added or copolymerized paraoxybenzoic acid, 5-sodium sulfoisophthalic acid, polyalkylene glycol, pentaerythritol and the like are also included.
[0026]
As the polyamide-based polymer, 6,6-nylon, 6,10-nylon, 6-nylon, 1,1-nylon, 1,2-nylon, 4-nylon, 4,6-nylon, and these are mainly used. A copolymer etc. can be illustrated.
[0027]
On the other hand, examples of the polyolefin resin include aliphatic α-olefins having 2 to 8 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, and 3-methyl-1-butene. , 1-hexene, 1-octene or other homopolymers or copolymers of two or more of these α-olefins, the α-olefin and other olefins, and / or a small amount of other ethylenically unsaturated monomers, such as Mention may be made of copolymers with ethylenically unsaturated monomers such as butadiene, isoprene, pentadiene-1, styrene, α-methylstyrene and mixtures of two or more thereof.
[0028]
Typical polyolefin resins include polypropylene resins and polyethylene resins. Examples of the polypropylene resins include propylene homopolymers, propylene containing 70% by weight or more, and the above α other than propylene. -Copolymers with olefins, such as ethylene-propylene copolymers, ethylene-propylene-butene copolymers, and the like.
[0029]
Examples of the polyethylene resin include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (L-LDPE).
[0030]
Among the melt flow rate of thermoplastic resin (hereinafter sometimes referred to as MFR), MFR (230 ° C, 2.18N) of polypropylene resin and MFR (190 ° C, 2.18N) of polyethylene resin can be spun. Although it will not specifically limit if it is a range, 1-100 g / 10min is preferable, More preferably, it is 5-70 g / 10min.
[0031]
As the thermoplastic resin other than the above, for example, a vinyl polymer is used, and specifically, polyvinyl alcohol, polyvinyl acetate, polyacrylate, ethylene vinyl acetate copolymer, syndiotactic polystyrene, or a copolymer thereof. Polymers can be used.
[0032]
The split-type conjugate fiber of the present invention can be arbitrarily combined with at least two thermoplastic resins among the above, but in fields requiring dyeing such as garments, for example, polyester resins and polyamide resins Combinations based on resins are preferred. In addition, in the industrial material field and sanitary material field where chemical resistance, lightness and cost are required, a combination mainly composed of polyolefin resin having high chemical resistance and advantageous in cost can be exemplified. In a field in which is required, a combination of a polypropylene resin and a polyethylene resin is suitable.
[0033]
Here, the thermoplastic resin can be arbitrarily combined. For example, a combination of a polyethylene terephthalate resin and a polyethylene terephthalate resin, a combination of polypropylene resin and a polypropylene resin, and a mixture having the same composition ratio. Is excluded from the scope of the present invention.
[0034]
In the combination of two components of a polypropylene resin and a polyethylene resin that are preferably used in the split type composite fiber of the present invention, the polypropylene resin has a resin component having a highest melting point (high melting point resin or A component and It may be abbreviated). Specific examples of such polypropylene resins include syndiotactic polypropylene and isotactic polypropylene polymerized with a Ziegler-Natta catalyst, a metallocene catalyst, or the like. Among the at least two thermoplastic resins constituting the split-type conjugate fiber of the present invention, when the MFR of the A component is MFR-A and the MFR of the B component is MFR-B, the polypropylene which is the A component The MFR-A of the resin may be in a range where melt spinning is possible, and there is no particular problem as long as the MFR-A after fiber forming is within the range of 10 to 100 g / 10 minutes by changing the spinning conditions and the like. The MFR-A after fiber molding is more preferably 10 to 70 g / 10 minutes. When MFR-A after fiber molding is less than 10 g / 10 minutes or more than 100 g / 10 minutes, it becomes difficult to spin into fine fibers with good spinnability.
[0035]
The polyethylene resin is a resin component having the lowest melting point in the combination of the two components (may be abbreviated as low melting point resin or B component), specifically, high density polyethylene, linear low A density polyethylene and a low density polyethylene can be illustrated. Moreover, the mixture of 2 or more types of these polyethylene may be sufficient. The MFR-B of the polyethylene-based resin as a raw material may be in a range that can be melt-spun, and if the MFR-B after fiber molding is within a range of 10 to 100 g / 10 minutes due to changes in spinning conditions and the like, there is a particular problem. There is no. The MFR-B after fiber molding is more preferably 10 to 60 g / 10 minutes. When MFR-B is less than 1 g / 10 minutes or more than 100 g / 10 minutes, it becomes difficult to spin into fine fibers with good spinnability.
[0036]
The ratio of MFR (MFR-A / MFR-B) is preferably from 0.1 to 5, more preferably from 0.5 to 3. When this value is less than 0.1 or exceeds 5, the flowability in the two-component die during melt spinning, bending, bending, or difference in melt tension after being discharged into a flat shape, during cooling It becomes difficult to maintain the spinnability due to factors such as a large difference in viscosity increase.
[0037]
The thermoplastic resin used in the present invention further includes an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizer, a nucleating agent, an epoxy stabilizer, a lubricant, an antibacterial agent within the range not impeding the effects of the present invention. Additives such as additives, flame retardants, antistatic materials, pigments, plasticizers and hydrophilic agents may be added as necessary.
[0038]
Next, the fiber cross section of the split composite fiber of the present invention will be described with reference to the drawings.
The split type composite fiber of the present invention is composed of, for example, a thermoplastic resin having at least two components as illustrated in FIG. 1, and in the fiber cross section, each component is alternately arranged in the major axis direction, and the cross section is bent. A split or conjugate fiber having a curved or flat shape and a ratio of the major axis L to the minor axis W (L / W) of the cross section of 3 to 20. Here, the long axis L is the direction in which the components are alternately adjacent to each other and represents the length of the longest portion of the cross-sectional shape (see FIG. 1). The minor axis W represents the contact surface direction of each component, that is, the thickness of the cross-sectional shape (see FIG. 1). When the L / W ratio is 3 or more, the surface area is large when the number of divided segments and the fineness are the same as those of ordinary circular cross-section split conjugate fibers, for example, radial and laminated split conjugate fibers, Since the contact area between adjacent components becomes small, a high-pressure liquid flow can be effectively received by the composite fiber, and it becomes easy to divide even at the same water pressure. In addition, if the composite fiber exceeds 20, the composite fiber can effectively receive a high-pressure liquid flow, but problems such as maintaining the spinnability, reducing the number of holes per unit area of the die, and reducing productivity are generated. To do.
[0039]
Furthermore, the splitting property is further improved because the cross-sectional shape is bent, curved or flat. Compared with the case where the fiber cross-sectional shape is a straight line (see FIG. 11), when the undrawn yarn obtained in the spinning process is drawn in the drawing process, for example, when the undrawn yarn is drawn in the drawing process, the fibers converged between rolls having a speed difference Is stretched with a strong stress, but at this time, the fibers are pressed with a high pressure. Moreover, when setting it as a short fiber, fibers will be pressed in the cutting process with the strong pressure equivalent to or more than a drawing process. For this reason, the split-type conjugate fiber of the present invention having a bent or curved fiber cross section is very easily crushed as compared with a straight cross-sectional shape, that is, splitting partially proceeds. Even if it is not divided, the contact interface of each component of the conjugate fiber is distorted, and the divided conjugate fiber of the present invention is very easy to divide.
[0040]
In this way, when the division has already partially progressed during the yarn making process, the papermaking method can be suitably used. In the case of the papermaking method, it is preferable that the division has already progressed partially because a dense and good web is formed at the papermaking stage. Further, when it is desired to suppress the progress of division during the yarn making process as much as possible, it is effective to set the draw ratio low. Specifically, the drawn yarn elongation preferably has 20% or more of the undrawn yarn elongation. Here, the bent or curved cross-sectional shape is not particularly limited, and for example, C-shaped (see FIGS. 1 to 5 and 10), S-shaped (see FIG. 7), M-shaped, N-shaped, L Examples include a letter shape, a V shape, a W shape (see FIG. 8), a hollow shape (see FIG. 9), and a wave shape. However, the present invention is not limited to these cross-sectional shapes. Moreover, the mixture of various cross-sectional shapes may be sufficient.
Further, examples of the flat shape include U-shaped, horseshoe-shaped, and U-shaped and horseshoe-shaped curved portions that are compressed and flattened, but the present invention is limited to these cross-sectional shapes. It is not something.
[0041]
As described above, since the fiber cross-sectional shape of the split composite fiber of the present invention is bent, curved, or flattened in the long axis direction, the same effect as that of the stretching and cutting process can be achieved by pressing between calender rolls. be able to. Therefore, for example, even when long fibers in an unstretched yarn state such as the spunbond method are directly accumulated on a conveyor, they are divided and refined by passing between pressurized calender rolls. It can be a body. Also, the fineness obtained by the conventional spunbond method and used in sanitary materials such as diapers is mainly around 2.2 dtex, but the split composite fiber of the present invention has one side surface of the fiber cross section. Since it is covered with one component, even in the case of a combination of resins having poor compatibility, the spinnability is not deteriorated due to peeling during spinning, and the fineness equivalent to that of the conventional product can be obtained.
[0042]
The ratio (a / b) of the fiber outer peripheral arc length a (fiber outer peripheral surface length a) of the B component of the resin constituting the split composite fiber of the present invention and the contact length b with the adjacent component is 0.1 to It is preferable to satisfy 2.5. When the ratio (a / b) is less than 0.1, the contact area with the adjacent component is larger than that of the outer peripheral surface of the fiber, and in order to achieve a high division ratio in a structure in which flakes are laminated, high energy is required. Necessary. On the other hand, if it exceeds 2.5, the number of divisions is reduced or the thickness of the flat shape becomes too thin, so that it is very difficult to produce with good spinnability.
[0043]
Furthermore, in the fiber cross section of the split-type conjugate fiber of the present invention, it is preferable that the ratio (c / W) between the minor axis W and the thickness c to the fiber surface portion of the B component satisfies 0.1 to 0.5. . Here, the minor axis W represents the contact surface direction of each component, that is, the thickness of the cross-sectional shape (see FIG. 1). The thickness c is a value (Wb) obtained by subtracting the contact length b of the B component from the thickness minor axis W of the cross-sectional shape, that is, the thickness up to the fiber surface portion of the B component covered with the A component (FIG. 1). If the ratio (c / W) is less than 0.1, there is a problem in spinnability due to peeling of adjacent resin during the spinning process. On the other hand, if it exceeds 0.5, the spinnability during the spinning process is good, but problems such as poor splitting after the splitting process occur.
[0044]
Moreover, in the fiber cross section of the split-type conjugate fiber of the present invention, the ratio (S1 / S2) of the area S1 surrounded by bending and bending to the cross-sectional area S2 (see FIG. 6) of the split-type conjugate fiber is 0.2 to It is preferable to satisfy 1.0. Here, S1 represents a portion surrounded by a straight line connecting both ends of the major axis and a bend or curve in the fiber cross section of the split composite fiber of the present invention, and represents a degree of the bend or the curve. That is, if S1 is increased, the major axis is greatly bent or curved. The ratio (S1 / S2) preferably satisfies 0.2 or more. If it is less than 0.2, the bending and bending are small, and the effect of the bending and bending becomes small. On the other hand, if it exceeds 1.0, it becomes difficult to maintain productivity due to problems such as the long axis of the composite fiber becoming too long or the thickness becoming extremely thin.
[0045]
The split type composite fiber according to the present invention is a combination of similar resins, which are difficult to split in the conventional split type composite fiber by taking the fiber cross-sectional shape as described above, and high energy is required for splitting. In particular, even a combination of polyolefin resins is excellent in splitting property and can be easily split. In addition, even if it is incompatible, such as a combination of polyolefin resin and polyester resin, it is possible to make finer in the spinning process because one side of the fiber cross section is covered with resin. Furthermore, handling in the post-processing step is easy. Moreover, even a web composed of short fibers used in the papermaking method can be divided with a high division ratio with good texture. From the above, the split type composite fiber of the present invention can be used for a combination of various compatible and incompatible resins. Here, the spinneret used for obtaining the fiber cross section of the split composite fiber of the present invention is not particularly limited as long as the split composite fiber can be obtained. A base disposed in an S shape, an M shape, an N shape, an L shape, a V shape, a W shape, a wave shape, a U shape, a horseshoe shape, or the like can be used.
[0046]
In the split type composite fiber of the present invention, the composite ratio of the composite fiber composed of at least two component thermoplastic resins is in the range of 10/90 to 90/10% by weight, and the total amount of the component resins used is 100%. %, More preferably 30/70 to 70/30% by weight, and most preferably 40/60 to 60/40% by weight. By setting it as the composite ratio of this range, it becomes a cross-sectional shape in which at least two types of thermoplastic resins are uniformly arranged, and a more uniform fiber molded body can be obtained.
[0047]
When the split type composite fiber obtained in the present invention is split by high-pressure liquid flow treatment or the like, the average fineness of the split ultrafine fiber is 0.5 dtex or less (sometimes referred to as dtex), particularly 0.3 dtex or less. It is preferable that Therefore, the number of divided segments of the split type composite fiber may be determined so that the average fineness of the ultrafine fiber is 0.5 dtex or less, and if the number of divided segments is large, there is an advantage that the fineness after splitting is reduced. Is preferably 4 to 32 segments for ease of fiber production.
[0048]
Although the single yarn fineness before a division | segmentation is not specifically limited, It is preferable that it is 0.5-10.0 decitex, More preferably, it is 1.0-6.0 decitex. In addition, the fineness of each segment does not need to be the same, and if the split type composite fiber is not completely divided, a plurality of different finenesses are placed between the undivided split fiber and the completely split ultrafine fiber. Of fibers may be mixed.
[0049]
Hereinafter, as an example of the split type composite fiber of the present invention, a method for producing a split composite fiber in which two components of a polypropylene resin and a high density polyethylene resin are combined will be exemplified.
A long fiber made of the resin is spun using an ordinary melt spinning machine. At the time of spinning, it is preferable to spin at a spinning temperature of 200 to 330 ° C., and the take-up speed is preferably about 40 m / min to 1500 m / min. Stretching may be performed as necessary. When stretching is performed, the stretching ratio is usually about 3 to 9 times. Further, the obtained tow is cut into a predetermined length to make a short fiber. Although the manufacturing process of the short fiber has been disclosed above, the long fiber tow can be made into a web by a fiber separation guide or the like without cutting the tow. After that, it is formed into a fiber molded body according to various uses through high-order processing steps as required. In addition, a fiber molded body that is wound up as a filament yarn after spinning and drawing, and knitted or woven to form a knitted fabric, or a fiber molded body that is knitted or woven and then knitted or woven to form a knitted fabric. You may form in.
[0050]
That is, here, the fiber molded body may be of any shape as long as it is in the form of a cloth, and examples thereof include woven fabrics, knitted fabrics, nonwoven fabrics, and non-woven fiber assemblies. Moreover, what was made into the form of cloth by methods, such as blended cotton, blended yarn, blended fiber, twisted twist, knit, and mixed fiber, is also included. Further, the non-woven fiber aggregate refers to a web-like product made uniform by a method such as a card method, an airlaid method, or a papermaking method, or a laminate of various woven fabrics, knitted fabrics, and nonwoven fabrics on the web-like product.
[0051]
In this step, after spinning the fiber, a surfactant can be attached to the fiber surface for the purpose of preventing the static electricity of the fiber and imparting smoothness to improve the processability of the fiber molded body. The type and concentration of the surfactant are appropriately adjusted according to the application. As a method of adhesion, a roller method, a dipping method, a pad dry method, or the like can be used. The attachment may be performed in any of the spinning process, the drawing process, and the crimping process. Furthermore, it is also possible to attach the surfactant after molding to a fiber molded body, for example, other than the spinning process, the stretching process, and the crimping process, regardless of whether the fibers are short fibers or long fibers.
[0052]
The fiber length of the split-type composite fiber of the present invention is not particularly limited. However, when a web is produced using a card machine, generally 20 to 76 mm is used. In the papermaking method and airlaid method, Those having a fiber length of 2 mm to 20 mm are preferably used. When the fiber length is less than 2 mm, the fiber moves due to physical impact, and the fiber itself is less likely to receive energy necessary for division. Further, when the fiber length greatly exceeds 76 mm, it is difficult to form a web with a card machine or the like, and it is difficult to obtain a uniform web.
[0053]
As an example of a method for producing a fiber molded body made of the split conjugate fiber of the present invention, a method for producing a nonwoven fabric is illustrated. For example, by using the short fiber manufactured by the split type composite fiber manufacturing method, a necessary basis weight web is prepared by a card method, an airlaid method, or a papermaking method. Further, the web may be directly produced by a melt blow method, a spun bond method or the like. The web produced by the above method can be divided and finely divided by a known method such as a needle punch method, a high-pressure liquid flow treatment, a pressurized calender roll, etc. to obtain a fiber molded body. Furthermore, the fiber molded body can be treated by a known processing method such as hot air or hot roll. When a web composed of very short fibers such as papermaking is divided and finely divided by a known method such as needle punching or high-pressure liquid flow treatment, the fibers are moved simultaneously with the physical stress. Since the formation may be poor, 5 to 30% by weight of a fiber that is heat-sealed at a melting point lower than the melting point of the resin constituting the split-type composite fiber of the present invention is preliminarily mixed. By performing heat treatment at the fusing temperature and preparing a heat-fused nonwoven fabric, formation defects can be suppressed.
[0054]
The basis weight of the fiber molded body of the present invention is not particularly limited, but is 10 to 200 g / m. ² Are preferred. The basis weight is 10g / m ² If the ratio is less than 1, the split composite fiber may be divided and refined by physical stress such as high-pressure liquid flow treatment to produce the nonwoven fabric, which may result in a poorly formed nonwoven fabric. The basis weight is 200 g / m ² If it exceeds 1, the basis weight is high, a high-pressure water flow is required, and it may be difficult to perform uniform division with good texture.
[0055]
The fiber molded body of the present invention can be used by mixing other fibers with the split-type composite fiber of the present invention, if necessary, within a range that does not hinder the present invention. Examples of such other fibers include synthetic fibers such as polyamide, polyester, polyolefin, and acrylic, natural fibers such as cotton, wool, and hemp, regenerated fibers such as rayon, cupra, and acetate, and semi-synthetic fibers.
[0056]
Next, the high-pressure liquid flow process will be described. As a high-pressure liquid flow apparatus used for high-pressure liquid flow treatment, for example, one or more injection holes having a hole diameter of 0.05 to 1.5 mm, particularly 0.1 to 0.5 mm, with a hole interval of 0.1 to 1.5 mm. A device arranged in multiple rows is used. A high-pressure liquid flow obtained by jetting from the jet holes at high water pressure is made to collide with the web placed on the porous support member. As a result, the undivided split composite fiber of the present invention is entangled and simultaneously refined by the high-pressure liquid flow. The injection holes are arranged in a row in a direction perpendicular to the traveling direction of the web. As the high-pressure liquid flow, normal temperature or warm water may be used, and other liquid may be arbitrarily used.
[0057]
The distance between the injection hole and the web is preferably 10 to 150 mm. If this distance is less than 10 mm, the formation of the fiber molded body obtained by this treatment is disturbed. On the other hand, if this distance exceeds 150 mm, the physical impact of the liquid flow on the web is weakened, resulting in entanglement and fine division. May not be adequately applied. The processing pressure of the high-pressure liquid flow is controlled by the production method and the required performance of the fiber molded body, but in general, a high-pressure liquid flow of 2 to 20 MPa should be jetted. Although it depends on the basis weight to be treated, etc., within the range of the treatment pressure, if the high-pressure liquid flow is processed by increasing the pressure from the low water pressure to the high water pressure sequentially, the entanglement and the web formation are not disturbed. Splitting and finening are possible. As the porous support member on which the web is placed when the high-pressure liquid flow is applied, for example, as long as the high-pressure liquid flow penetrates the web, such as a mesh screen or a perforated plate made of 50-200 mesh metal mesh or synthetic resin There is no particular limitation.
[0058]
In addition, after performing the high-pressure liquid flow treatment from one side of the web, by subsequently inverting the entangled web and performing the high-pressure liquid flow treatment, it is possible to obtain a dense and well-formed fiber molded body on both sides. it can. Furthermore, after performing a high-pressure liquid flow process, a water | moisture content is removed from the fiber molded object after a process. In removing this moisture, a known method can be employed. For example, after removing moisture to some extent using a squeezing device such as Mangroll, moisture can be completely removed using a drying device such as a hot air circulation dryer to obtain the fiber molded body of the present invention.
[0059]
When a high-pressure liquid flow treatment is applied to the web containing the split-type conjugate fiber of the present invention by the above-described method to make a finely divided fiber, a split-type conjugate fiber having a conventional fiber cross section (FIG. 12) is obtained. Compared to the above, it is easy to divide, and the physical impact by the high-pressure liquid flow is small. For this reason, since the formation of high-pressure liquid flow, which is the rate-limiting step of the nonwoven fabric processing process, is improved by reducing the pressure of the high-pressure liquid flow, for example, the pressure of the high-pressure liquid flow can be lowered. Or problems such as opening of through holes can be improved.
[0060]
As described above, even a split type composite fiber composed of a similar resin that is considered to be most difficult to split can be easily split, and a dense and well-formed fiber molded body can be obtained. Thereby, it can be suitably used not only in the field of industrial materials such as battery separators and wipers but also in the field of sanitary materials and clothing.
[0061]
Furthermore, a laminated fiber molded body (hereinafter referred to as α type) in which at least one sheet selected from a nonwoven fabric, a film, a knitted fabric, and a woven fabric is laminated on one side or both sides of the fiber molded body of the present invention, and further, the fiber On the contrary, a laminated fiber molded body (hereinafter referred to as β type) in which the molded body is laminated on both surfaces of the sheet can be obtained.
In the case of the α type, it is preferable that the divided fiber molded body is laminated on one side or both sides of the sheet because the division efficiency is good. In the case of the β type, the fiber molded body is divided before and after the lamination, but the division treatment after the lamination is particularly preferable because an entanglement effect between the sheet and the fiber molded body is obtained. Any of these laminated fiber molded products (α type) and (β type) should also be suitably used in the field of hygiene materials represented by absorbent articles such as diapers and napkins, and in the field of industrial materials such as wipers and battery separators. Can do.
[0062]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited by this. The terms and methods for measuring physical properties in Examples and Comparative Examples are as follows.
[0063]
(1) Melt flow rate: measured in accordance with JIS K7210.
Raw material polypropylene resin: Condition 14
Raw material polyethylene resin: Condition 4
Polyolefin resin after fiber molding: Condition 14
[0064]
(2) L / W measurement method
The following values were calculated from cross-sectional photographs of 10 undivided fibers selected arbitrarily, and L / W was calculated from the average value.
L: represents the longest part of the fiber cross-sectional shape in the direction in which the components are alternately adjacent to each other (see FIG. 1)
W: represents the contact surface direction of each component, that is, the thickness of the cross-sectional shape (see FIG. 1).
[0065]
(3) a / b measurement method
The following values were calculated from cross-sectional photographs of 10 undivided fibers selected arbitrarily, and a / b was calculated from the average value.
a: Average value of the outer peripheral surface length of one component (see FIG. 1)
b: Average value of contact length of 1 component (see FIG. 1)
[0066]
c / W measurement method
The following values were calculated from cross-sectional photographs of 10 undivided fibers selected arbitrarily, and c / W was calculated from the average value.
c: (Wb) (see FIG. 1)
W: represents the contact surface direction of each component, that is, the thickness of the cross-sectional shape (see FIG. 1).
[0067]
(5) S1 / S2 measurement method
The area of S1 and S2 was calculated from a fiber cross-sectional photograph of 10 undivided fibers selected arbitrarily, and S1 / S2 was calculated from the average value (see FIG. 6).
S1: Area of a portion surrounded by a straight line connecting both ends of the long axis and bending or bending
S2: Cross-sectional area of the split composite fiber of the present invention
[0068]
(6) Spinnability
The spinnability at the time of melt spinning was evaluated in the following three stages according to the occurrence rate of yarn breakage.
○: No thread breakage occurs and operability is good.
Δ: Thread breakage once or twice per hour
X: Yarn breakage occurs 4 times or more per hour, and there is a problem in operation.
[0069]
(7) Stretch ratio
The following formula was used for calculation.
Stretch ratio = take-up roll speed (m / min) / feed roll (m / min)
[0070]
(8) Fiber tensile strength and elongation
According to JIS-L1013 method, it was measured at a yarn length of 100 mm and a tensile speed of 100 mm / min using an autograph AGS500D manufactured by Shimadzu Corporation.
[0071]
(9) Tensile strength and elongation of nonwoven fabric
The nonwoven fabric breaking strength of MD direction was measured for the nonwoven fabric of 5 cm width using Shimadzu Corporation autograph AGS500D. Measurement was performed at a test length of 100 mm and a tensile speed of 200 mm / min, and the measurement temperature was room temperature.
[0072]
(10) Measurement of split ratio
The non-woven fabric after the division is included with wax, and is sliced at right angles to the fiber axis with a microtome to create a sample piece. This is observed with a microscope, and the cross-sectional image of the fiber is image-processed to measure the total cross-sectional area (A) of the fiber in which 70% or more of the segments are divided and the total cross-sectional area (B) of the undivided fiber, It was calculated by the following formula.
Division rate (%) = {A / (A + B)} × 100
[0073]
(11) Single yarn fineness after division
From the fineness before division and the number of segments that can be divided, the single yarn fineness after division fineness was calculated from the following equation.
Fineness after division (dtex / f) = fineness before division (dtex / f) / number of segments that can be divided (pieces)
[0074]
(12) Formation
Ten panelists evaluated as follows according to the result of visually observing the fiber distribution spots of the non-woven fabric (1 m square) after the split fine processing.
○: 7 or more people felt that there were few spots and no through holes.
Δ: 4 to 6 people felt that there were few spots and no through holes.
X: 3 or less felt that there were few spots.
[0075]
(13) High pressure liquid flow treatment
A web produced by a roller card machine, an airlaid machine, a paper machine, etc. is placed on a conveyor belt made of 80 mesh plain weave, and at a conveyor belt speed of 20 m / min, the nozzle diameter is 0.1 mm and the nozzle pitch is 1 mm. Passed and jetted high pressure liquid stream. First, after preliminary treatment (2 stages) at 2 MPa, 4 stages treatment was performed with a high-pressure liquid flow having a water pressure of 5 MPa. The web was inverted, and further processed in four stages with a high-pressure liquid flow having a water pressure of 5 MPa, to obtain a non-woven fabric that had been divided and refined. Here, the step is the number of times that the nozzle has passed directly under the nozzle.
[0076]
(14) Pressure (split) roll
Induction heating hydraulic two-roll clearance machine (manufactured by Yuri Roll Co., Ltd.)
Processing temperature: Atmospheric temperature
Treatment linear pressure: 40 N / mm
Processing speed: 10m / min
[0077]
(15) Water pressure resistance
The measurement was performed according to JIS L1092.
[0078]
Examples 1-3
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and having a single yarn fineness of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained unstretched yarn was stretched at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight.
To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. Using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd., a web was obtained by drying at 105 ° C. for 3 minutes and pre-bonding. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0079]
Example 4
Polypropylene resin (polypropylene homopolymer) is used as the high melting point resin (A component), high density polyethylene resin is used as the low melting point resin (B component), and both the A component and B component resins are used using the split composite fiber die. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 2 having a single yarn fineness of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 1.5 times to give crimps and cut into 51 mm.
The obtained short fiber was used as a web with a roller card machine, and the high-pressure liquid flow treatment was performed on the web, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. When the fiber molded body was used as a surface material for adult diapers, it was excellent in touch (soft feeling), non-woven fabric strength, etc., and very good as an absorbent article.
[0080]
Example 5
In accordance with Example 1 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 3 was used, the split type composite fiber was spun and a fiber molded body was produced.
[0081]
Example 6
Except that linear low-density polyethylene was used instead of high-density polyethylene, spinning of split-type composite fibers and production of a fiber molded body were performed in accordance with Example 1.
[0082]
Example 7
Except that low-density polyethylene was used instead of high-density polyethylene, spinning of split-type composite fibers and production of a fiber molded body were performed in accordance with Example 1.
[0083]
Example 8
Polypropylene resin (polypropylene homopolymer) is used as the high melting point resin (A component), high density polyethylene resin is used as the low melting point resin (B component), and both the A component and B component resins are used using the split composite fiber die. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and a single yarn fineness of 20.0 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained unstretched yarn was stretched at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. Using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd., a web was obtained by drying at 105 ° C. for 3 minutes and pre-bonding. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0084]
Example 9
According to Example 8, spinning of the split composite fiber and preparation of the fiber molded body were performed except that the split composite fiber base for obtaining the fiber cross section shown in FIG. 2 was used.
[0085]
The spinning conditions, fiber properties, shapes, nonwoven fabric properties, split ratios, and the like of Examples 1 to 9 are shown in Table 1 described later.
[0086]
Example 10
Relative viscosity (measured at 20 ° C using an equal mixture of phenol and ethane tetrachloride as a solvent) 0.60 PET (Kanebo Co., Ltd., K101) is a high melting point resin (component A) and a low melting point resin. Using polypropylene resin (MFR: propylene homopolymer of 16 g / 10 min) as (B component), using a split type composite fiber die, the volume ratio of both the A component and B component resins is 50/50, A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 having a single yarn fineness of 15.0 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 3.3 times, attached with a paper finishing agent, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of a polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a square sheet machine (25 cm × 25 cm) is used to make a paper. The web. Using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd., drying was carried out at 105 ° C. for 3 minutes and pre-adhering to obtain a web. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0087]
Example 11
A split type composite fiber was spun and a fiber molded body was produced in accordance with Example 1 except that the split type composite fiber base for obtaining the fiber cross section shown in FIG. 4 was used.
[0088]
Example 12
Polypropylene resin (polypropylene homopolymer) is used as the high melting point resin (A component), high density polyethylene resin is used as the low melting point resin (B component), and both the A component and B component resins are used using the split composite fiber die. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and having a single yarn fineness of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. The web was dried at 105 ° C. for 3 minutes using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd. and pre-bonded to obtain a web. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0089]
Example 13
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 was spun by the spunbond method. A composite fiber group discharged from a spinneret is introduced into an air soccer ball and pulled and drawn to obtain a composite long fiber having a single yarn fineness of 2.0 dtex, and then the long fiber group discharged from the air soccer ball is charged by a charging device. After the same charge is applied and charged, the fibers are opened by colliding with the reflector, and the opened long fiber group is collected as a long fiber web on an endless net-like conveyor provided with a suction device on the back surface. The long fiber web was divided by a pressure roll and then processed by an embossing roll machine having an area ratio of 15% heated to 120 ° C. to obtain a fiber molded body.
[0090]
The spinning conditions, fiber properties, shapes, nonwoven fabric properties, split ratios, etc. of Examples 10 to 13 are shown in Table 2 described later.
[0091]
Example 14
Polypropylene resin (polypropylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 10 and a single yarn fineness of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of a polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a square sheet machine (25 cm × 25 cm) is used to make a paper. The web. This was dried at 105 ° C. for 3 minutes using a Yankee dryer manufactured by Kumagai Siki Kogyo Co., Ltd. and pre-bonded to obtain a web. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body. The spinning conditions, fiber properties, shape, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0092]
Example 15
In accordance with Example 1 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 11 was used, the split type composite fiber was spun and a fiber molded body was produced. The spinning conditions, fiber properties, shapes, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0093]
Comparative Example 1
In accordance with Example 1 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 12 was used, the split type composite fiber was spun and a fiber molded body was produced. The spinning conditions, fiber properties, shapes, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0094]
Comparative Example 2
In accordance with Example 13 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 12 was used, the split type composite fiber was spun and a fiber molded body was produced. The spinning conditions, fiber properties, shapes, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0095]
Examples 16, 17
The basis weight of 10 g / m in the previous step (before the high-pressure liquid flow treatment) for obtaining a fiber molded body according to Example 1 ² Web (abbreviated as Web A). Next, polypropylene (core) / high-density polyethylene (sheath) sheath-core composite fiber (ESC fiber, Chisso Corporation) 2.2 dtex × 51 mm short fiber was used, and the basis weight was 10 g / m. ² Card web (abbreviated as Web B). After performing the high-pressure liquid flow treatment, the web A is laminated on the upper layer, the web B is laminated on the lower layer (Example 16), and the web A is laminated on the upper and lower layers and the web B is laminated on the middle layer (Example 17). And dried with a dryer at 80 ° C. to obtain a fiber molded body. Furthermore, when this fiber molded body was used as a wiper for wiping, both Examples 16 and 17 showed very excellent wiping properties.
[0096]
Example 18
Polypropylene resin (polypropylene homopolymer) is used as the high melting point resin (A component), high density polyethylene resin is used as the low melting point resin (B component), and both the A component and B component resins are used using the split composite fiber die. The split composite fiber having the fiber cross-sectional shape shown in FIG. 1 is spun by the spunbond method to obtain a single yarn fineness of 2.0 dtex, and the basis weight for the middle layer is 10 g / m. ² Got the web. Next, in the combination of the resins, using a sheath core type composite fiber die, the A component is the core side, the B component is the sheath side, the volume ratio of both the A and B resins is 50/50, and the single yarn A composite fiber having a fineness of 2.0 dtex is spun by the spunbond method, and the basis weight is 5.0 g / m. ² And then laminating the web as an upper and lower layer on the intermediate layer web, dividing it with a pressure roll, and then treating it with an embossing machine having an area ratio of 15% heated to 120 ° C. Got. Furthermore, when the laminated fiber molded body was used as a surface material for adult diapers, it was excellent in water pressure resistance, non-woven fabric strength, etc., and very good as an absorbent article.
[0097]
[Table 1]

[0098]
[Table 2]

[0099]
As is apparent from Tables 1 and 2, the fiber molded body and the laminated fiber molded body obtained in each example of the examples of the present invention are divided at a high split ratio even under the same conditions as in the comparative examples. That is, even without performing a high-pressure liquid flow treatment at a high water pressure as in the prior art, division and finening proceed easily, so even a nonwoven fabric with a relatively low basis weight can be produced without disturbing the formation, Furthermore, the cost of high pressure liquid flow treatment can be greatly reduced.
[0100]
【The invention's effect】
Since the split-type composite fiber of the present invention is very easy to split, it can be easily made into ultrafine fibers without adding any special additives for easy splitting and without increasing the physical impact. For this reason, when the split type composite fiber of the present invention is used, a dense and well-formed fiber molded body can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 2 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 3 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 4 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 5 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 6 is a schematic diagram showing an area (S1) surrounded by bending or bending and a cross-sectional area (S2) of a split-type conjugate fiber.
FIG. 7 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 8 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 9 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 10 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 11 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 12 is a schematic diagram of a fiber cross section of a split-type composite fiber used in a comparative example.
[Explanation of symbols]
L: Represents the length of the longest section in the direction in which the components of the composite fiber are alternately adjacent to each other.
W: Represents the thickness of the cross-sectional shape in the contact surface direction of each component of the composite fiber.
a: Represents the fiber outer peripheral length of the component B constituting the composite fiber.
b: Represents the contact length with the adjacent component of the B component constituting the composite fiber.
c: represents a length obtained by subtracting the contact length b of the B component constituting the composite fiber from the thickness W of the cross-sectional shape.
S1: An area of a portion surrounded by a straight line connecting both ends of the long axis and bending or bending.
S2: Represents the fiber cross-sectional area of the composite fiber.

Claims

A split-type conjugate fiber composed of at least two-component thermoplastic resin (excluding alkali-soluble polyester) , wherein each component in the fiber cross section is arranged in the major axis direction, and one side surface of the fiber cross section Is a split type composite fiber for splitting treatment with physical stress, characterized in that it is covered with only one component and the other one side surface is exposed with two components alternately.

A split type composite fiber composed of a combination of polyolefin resins or a combination of a polyolefin resin and a polyester resin, wherein each component in the fiber cross section is arranged in the major axis direction, and one side surface of the fiber cross section Is a split type composite fiber for splitting treatment with physical stress, characterized in that it is covered with only one component and the other one side surface is exposed with two components alternately.

The fiber section of the split type composite fiber is a bent, curved or flat-shaped composite fiber, and the ratio (L / W) of the major axis L to the minor axis W of the cross section is 3 to 20 The split type composite fiber according to claim 1 or 2 .

In the fiber cross section of the splittable conjugate fiber of claim 3 wherein the ratio of the area S1 surrounded by the bent or curved the splittable conjugate fiber of the cross-sectional area S2 (S1 / S2) is 0.2 to 1.0 Split composite fiber.

The melt flow rate of at least two thermoplastic resins constituting the fiber after fiber molding is 10 to 100 g / 10 min, and the resin component having the highest melting point (hereinafter referred to as A) The ratio (MFR-A / MFR-B) of the melt flow rate (MFR-A) of the component) to the melt flow rate (MFR-B) of the resin component having the lowest melting point (hereinafter referred to as component B) is 0. The split type composite fiber according to any one of claims 1 to 4 , which is .1 to 5 .

The ratio (a / b) of the fiber outer peripheral surface length a of the B component constituting the fiber and the contact length b of the adjacent component in the fiber cross section of the split composite fiber is 0.1 to 2.5. The split type composite fiber according to any one of 1 to 5 .

In the fiber cross section of the splittable conjugate fiber, and a minor axis W, claim 1-6 ratio between the thickness c to the fiber surface portion of the B component (c / W) is 0.1 to 0.5 2. Split type composite fiber according to item 1.

The split-type composite fiber according to any one of claims 1 to 7, wherein the single-fiber fineness before splitting of the split-type composite fiber is 0.5 to 10 dtex, and the single-fiber fineness after splitting is 0.5 dtex or less.

A fiber molded body containing at least 30% by weight or more of the split-type conjugate fiber according to any one of claims 1 to 8, and 50% or more of the split-type conjugate fiber being split.

The fiber molded body according to claim 9, wherein the fiber molded body is a fiber assembly.

The fiber molded body according to claim 9 or 10, wherein the fiber molded body is a fiber assembly obtained by a spunbond method.

The laminated fiber molded object formed by laminating | stacking another sheet | seat on the single side | surface or both surfaces of the fiber molded object of any one of Claims 9-11.

The laminated fiber molded object formed by laminating | stacking the fiber molded object of any one of Claims 9-11 on both surfaces of another sheet | seat.

A laminated fiber molded body, wherein the sheet according to claim 12 or 13 is selected from at least one of a nonwoven fabric, a film, a knitted fabric, and a woven fabric.

An absorbent article using the fiber molded body or laminated fiber molded body according to any one of claims 9 to 14.

The wiper using the fiber molded object or laminated fiber molded object of any one of Claims 9-14.

The battery separator using the fiber molded object or laminated fiber molded object of any one of Claims 9-14.