JP4142903B2 - Composite fiber nonwoven fabric and composite nonwoven fabric thereof - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、一般的にステープル複合繊維を製造する溶融粘度をもつ熱可塑性樹脂を用いて、繊維の腰など繊維物性がステープル複合繊維と同等で、且つより微細なまたはより太い複合繊維を製造し、ステープル複合繊維を用いて不織布化するに際して、繊度の制限を生じるローラーカード等を使用せず、少なくとも直接開繊した繊維ウエブなどの繊維集合体または溶融接着して一体化した不織布とする、複合繊維が作れるメルトブロー法により繊維化と不織布化を行った複合繊維不織布とこれらを応用した複合不織布に関するものである。本発明は、特に従来からステープル繊維を作る上で、紡糸時に紡出繊維間で溶融接着することが問題であった、低融点や粘着性や表面硬度が軟質の樹脂を用いた複合繊維を自由に直接不織布化でき、繊維が細いため不織布化するに技術を要した細繊度繊維を含んだ不織布、そして、堅くて脆い樹脂や曳糸性が劣って単独では繊維化できない樹脂を用いた複合繊維の不織布を容易に作ることができ、できたこれらの複合繊維不織布とこれらを応用した複合不織布に関するものである。さらには、界面活性剤などの繊維処理剤を嫌うエレクトレット不織布などの用途向けの繊維処理剤剤レスの接着不織布及びエレクトレット不織布であって、ビル空調フイルター、吸塵カーテンやマスク素材等のエアフィルター用素材として有用であり、これらフィルターとして不織布を折り畳み成型加工しやすい不織布に関するものである。
【０００２】
【従来の技術】
二つの異なる成分からなる複合繊維で構成するメルトブローン不織布については特開平５−１７９５１１、特開平５−２１４６５５、特開平５−２６３３０７、特開２００１−９８４５３等の各公知文献において開示されている。これらはいずれも融点の異なる二つの熱可塑性樹脂をメルトブロー法により不織布を得る技術に関するものである。
【０００３】
【発明が解決しょうとする課題】
本発明者は、特開２００１−９８４５３号でエレクトレット不織布を提案したが、厚みが薄くてロータリープリーツ折り機でプリーツ折りできない問題と、期待に反して不織布の圧力損失が高いという問題に突き当たった。現状のメルトブロー不織布は、その構成繊維が単一成分でなるため、ほとんどの該不織布が自己融着接着していないもので、リントフリー性に問題があり、且つ嵩が低くてペーパーライクで薄い不織布でしかなかった。前記したように、過半をメルトブロー法によって作った繊維で構成した本発明の不織布は、嵩と堅さが要求されるプリーツフイルターへの適応を主として考え出されたものであり、少なくとも嵩がある過半をメルトブロー法によって作った繊維で構成した不織布を提供することを目的の一つとしている。全てをポリオレフィン樹脂としたエレクトレット不織布では、その絶縁抵抗が大きくて、厚みを大きくするために不織布の目付を上げると、目付が９０ｇ／ｍ2 を超えると電界の貫通が急に不良となり、エレクトレット付与効果が急激に低下し、高捕集効率のエレクトレットフィルターを作ることが出来ないことも判明し、不織布の嵩高化と低圧損化が急務となった。また含浸ポリエステル繊維不織布を基布に貼り付けたエレクトレット不織布では、その目付が１２０ｇ／ｍ2 でもエレクトレット化は容易であり、特に全てをポリオレフィン樹脂としたエレクトレット不織布で問題が深刻であった。このような問題に鑑み、市販のメルトブロー不織布を調査したが、メルトブローの噴出気流にそって各構成繊維がかなり整然と揃って集積されていることが分かった。すなわち、不織布を構成する繊維を細くすればするほど薄い不織布となり、圧力損失（圧損）の高い不織布となるのは自明で、この方法では不織布の嵩高さと低圧損化が達成できないのである。また上記の従来技術ではメルトブローン不織布はノズルから熱風によりコンベアベルト上になるべく均一に積層されるように製造されるので、得られる不織布は平滑であり、ペーパーライクなものになりがちであった。このような不織布はプリーツ折り機のギアロールにかかりにくく作業性が悪く、また不織布の目付に対する嵩が少なくフィルターとして補集効率を上げようとすると圧損が大きくなる欠点があった。またポリブテン−１樹脂はポリプロピレン樹脂より硬いため、本発明のポリプロピレン／ポリブテン−１複合繊維のメルトブロー不織布は、ポリプロピレン単独のメルトブロー不織布よりはるかに硬くて腰のある不織布であるが、プリーツ折りフイルターとして用いるに、もっと硬くて腰のある不織布にする問題があった。また、全てがポリオレフィン樹脂でなるエレクトレット不織布を作る場合、基布としてポリプロピレン製のスパンボンド不織布を用い、本発明のポリプロピレン／ポリブテン−１複合繊維を該スパンボンド不織布に吹き付けて熱接着させる不織布では、長期運転すると、一部が熱接着し、他は接着せず一体化していない不織布ではなく、全てが熱接着している不織布では、部分的に長手方向に連続した帯状に基布が溶融またはフィルム化する現象が発生し、当該部分の圧損が高くなり、幅方向の通気性や塵埃捕集効率などの品質むらが発生し問題であった。また、基布を含浸ＰＥＴ不織布とする既発明の不織布では、ＰＥＴ不織布との接着力が弱く、剥離しやすい問題があった。本発明の不織布はその構成層の大部分をメルトブロー手法により製造した複合繊維で構成した不織布であって、嵩高性であり、フィルターとして使用中に繊維の脱落が少なく、長期間の使用でも圧損が小さく、また十分なエレクトレット化が可能であり、上記のような問題点を解決することを目的とする。
【０００４】
【課題を解決するための手段】
従来のメルトブロー法は、溶融樹脂をノズルから簾状に噴出させ繊維としてコンベア上に集積してから繊維同士を熱接着させてメルトブローン不織布とする方法を基本としていたが、本発明者らは溶融樹脂の噴出からコンベアへ落下するまでの間に、隣り合う複数本の繊維同士を部分的に接触させて、繊維が凝集し絡み合い熱接着した塊を積極的に発生させこれを部分的、局所的に偏在させることを実現して新規なメルトブローン不織布を得て上記課題を解決することができた。
このようにして得られたメルトブローン不織布は繊維塊が不織布中に多数散在しており、繊維塊の部分はその分だけ不織布の厚みが大きくなっており、繊維塊の周辺は集積される繊維間の空隙を大きく作る構造になる。さらにその上から繊維を集積することで厚み方向に立体的な集積条件を作って密度を下げる繊維集積を積極的に行い、結果として繊維間間隙を広げて流体の通過性を向上させることができたのである。すなわち、圧損を下げる効果を生じさせると共に、嵩高化も達成できたのである。
【０００５】
すなわち本発明は、融点の異なる２以上の熱可塑性合成樹脂からなり、各熱可塑性合成樹脂の融点（Ｔｍ：℃）が６０≦Ｔｍ＜２７０を満たし、その溶融流動性メルトフローレート（ＭＦＲ：ｇ／１０分；測定温度は、Ｔｍ≦２００のとき２３０℃、２００＜Ｔｍのとき２９０℃、加重は２．１６９Ｋｇ、ＪＩＳ−Ｋ−６７６０に準ず）が、５＜ＭＦＲ＜２００であり、低融点成分が繊維表面の大半を占めている複合繊維を構成繊維とするメルトブロー法により製造された不織布であって、前記複合繊維の隣り合う複数本の繊維同士を噴出中に部分的に空中で接触させて繊維を凝集し熱接着させた繊維塊が、不織布中に部分的、局所的に偏在して不織布表面に凸部を形成し、該繊維塊の周辺は繊維塊が存在していない部分より構成繊維の間隔が広がり繊維密度が低下していることを特徴とする、嵩高さ（厚さμｍ／目付ｇ／ｍ2）が８以上である複合繊維不織布である。
【０００６】
上記複合繊維は平均繊維径（ｄ：μｍ）が０．３＜ｄ＜２００、構成する複数の各熱可塑性樹脂成分が、その融点（Ｔｍ：℃）を６０≦Ｔｍ＜２７０、その溶融流動性メルトフローレート（ＭＦＲ：ｇ／１０分；測定温度は、Ｔｍ≦２００のとき２３０℃、２００＜Ｔｍのとき２９０℃、加重は２．１６９Ｋｇ、ＪＩＳ−Ｋ−６７６０に準ず）が、５＜ＭＦＲ＜２００である熱可塑性合成樹脂であることが好ましい。
【０００７】
上記複合繊維の熱可塑性樹脂成分は、低融点成分が密度（Ｄ：ｇ／ｃｍ3 ）を０．９０５≦Ｄ＜０．９３０、融点（Ｔｍｓ：℃）を１１５＜Ｔｍｓ＜１３０とするポブテン−１であり、もう一つがポリプロピレンであることが好ましい。
【０００８】
さらに本発明は上記ポリブテン−１とポリプロピレンからなる複合繊維不織布の少なくとも片面に繊維径が１５μｍ以上の繊維からなる表面不織布層が配され、該複合繊維不織布を構成する複合繊維の少なくとも低融点の成分による熱接着で一体化している複合不織布である。
【０００９】
上記複合不織布の好ましい態様のひとつは目付が３０〜４００ｇ／ｍ2 である複合不織布である。
【００１０】
上記表面不織布層は、繊維がプロピレンを主成分とするホモポリマー、プロピレンを主体とする共重合体のうち１以上の樹脂からなるスパンボンド不織布であることが好ましい。
【００１１】
上記表面不織布層は、ポリエチレンテレフタレート（ＰＥＴ）樹脂からなる繊維が樹脂含浸され、該樹脂で接着一体化された不織布であり、少なくともその１表面にポリオレフィン樹脂でなる繊維状の固着物が散在していることが好ましく、該表面に本発明の複合繊維不織布が配され、融着一体化して複合不織布とすることが好ましい。この繊維状の固着物としては例えばポリプロピレンスパンボンド不織布等からなる樹脂含浸不織布が好ましい。該樹脂としては例えばアクリル樹脂等が適用される。こうした構成により本発明の複合不織布は該樹脂による接着性が付与され不織布相互の剥離強力に優れた複合不織布と成り得る。
【００１２】
さらに本発明は、上記ポリブテン−１とポリプロピレンからなる複合繊維は、平均繊維径（ｄ：μｍ）が１０＜ｄ＜２００である上記複合不織布の上にさらに平均繊維径（ｄ：μｍ）が０．３＜ｄ＜２０の複合繊維を構成繊維とする上記複合繊維不織布が配され、各不織布層間は複合繊維の低融点成分により熱接着して一体化している複合不織布である。
【００１３】
上記複合不織布の好ましい態様のひとつは目付が６０〜４００ｇ／ｍ2 である複合不織布である。
【００１４】
本発明の好ましい態様のひとつは、上記複合不織布がエレクトレット加工され、少なくともポリブテン−１とポリプロピレンからなる複合繊維がエレクトレット化されている複合不織布である。
【００１５】
また本発明の好ましい態様のひとつは、表面不織布層は界面活性剤などの親水性化学物質が付着されていないポリプロピレン繊維またはポリエチレン繊維で構成されており、この表面不織布層が両面に配されている、上記ポリブテン−１とポリプロピレンからなる複合繊維不織布であって、該複合繊維不織布を構成する複合繊維の少なくとも低融点の成分による熱接着で一体化している複合不織布であってエレクトレット化されているものである。
【００１６】
また本発明の好ましい態様のひとつは、上記ポリブテン−１とポリプロピレンからなる複合繊維不織布の少なくとも片面に繊維径が１５μｍ以上の繊維からなる表面不織布層が配され、該複合繊維不織布を構成する複合繊維の少なくとも低融点の成分による熱接着で一体化している複合不織布の複合繊維不織布面側に繊維径が５μｍ以上のポリプロピレン繊維とレーヨン繊維とからなる親水性繊維層が積層され複合繊維の少なくとも低融点の成分による熱接着により一体化しておりエレクトレット化されている複合不織布である。
【００１７】
また本発明の好ましい態様のひとつは、上記ポリブテン−１とポリプロピレンからなる複合繊維不織布の少なくとも片面に繊維径が１５μｍ以上の繊維からなる表面不織布層が配され、該複合繊維不織布を構成する複合繊維の少なくとも低融点の成分による熱接着で一体化している複合不織布の少なくとも片面にレーヨン繊維層と活性炭素繊維層とポリプロピレンスパンボンド不織布層の３層からなる積層不織布が複合繊維の低融点の成分による熱接着で一体化しておりエレクトレット化されている複合不織布である。
【００１８】
また本発明の好ましい態様のひとつは、メルトブローン不織布以外の不織布層の繊維は難燃化している上記複合不織布である。
【００１９】
【発明の実施の態様】
本発明の不織布を構成する複合繊維は融点が異なる２以上の熱可塑性樹脂成分からなり、好ましくは図１に示すような２成分が鞘芯型、猫目型あるいは１成分が他の成分によって二つに分離された三層型のような断面構造をもち低融点成分が繊維表面の大半を占めている繊維である。また多芯型や３層型や１成分が少なくとも複数に区分され他の成分で区分けされた繊維断面が蜜柑型や風車型などの分割繊維型である繊維であり、繊維形状は円や楕円などの円型を基本とするが、角の取れた異型である場合も有り得る。
【００２０】
このような複合繊維を形成する熱可塑性樹脂は一般的なステープル複合繊維を製造する溶融粘度のものを用いておりその溶融流動性メルトフローレート（ＭＦＲ：ｇ／１０分；測定温度は、Ｔｍ≦２００のとき２３０℃、２００＜Ｔｍのとき２９０℃、加重は２．１６９Ｋｇ、ＪＩＳ−Ｋ−６７６０に準ず）が、５＜ＭＦＲ＜２００である熱可塑性合成樹脂である。このような溶融流動性をもつ熱可塑性樹脂を使用してノズルから紡糸された複合繊維の隣り合う繊維同士を噴出中に部分的に空中で接触させて構造中に繊維塊をもつ不織布を形成する。
【００２１】
ノズルから紡糸された複合繊維の隣り合う繊維同士を噴出中に部分的に空中で接触させて、部分的、局所的に偏在させた凝集し絡み合い融着接着させた塊を発生させる工程において、ノズルの吐出孔の間隔（円形の吐出孔の中心間の距離）が従来の３ｍｍ程度ではコンベアまで５〜２０ｃｍ程度の高さの間に隣り合う繊維同士を作為的に、接触させるに無理があった。
【００２２】
本発明者らは吐出孔の多いノズルを考案し、吐出孔間隔を１ｍｍ未満とすることで、作為的に、凝集し絡み合い融着接着させた塊を発生させることに成功した。すなわち、凝集し絡み合い融着接着させた塊が多い太繊維の不織布を作る時は、吐出量を多くし、わずかな熱風流速の低下とすると良く、凝集し絡み合い融着接着させた塊が少ない不織布を作る時は、吐出量を絞り、熱風流速を上げることで達成できる。これは樹脂のバラス効果を利用している。このようにして紡糸された複合繊維は実質的に連続しておりそれらの複数本が部分的に融着して融着部分となり、また一本づつの複合繊維として連続するのである。
【００２３】
本発明の複合繊維の繊維径は、融着部分と非融着部分で繊維径が変化しており、太い部分は概ね２００μｍ未満であり、実質的に連続したとは、なんらかの個別の理由で繊維が千切れない限り、製造条件としては千切れを意図していないことを言う。
【００２４】
このようにメルトブローン不織布を製造することにより、従来のメルトブロー法による、同じ熱可塑性樹脂を用いて同様の目付のメルトブローン不織布より２０〜１００％の厚みのある不織布を得ることができた。
なお本発明において不織布の厚みはＪＩＳＬ−１９１３−６．１．２Ａ法により測定した。
【００２５】
本発明では、ハイフロー（低粘度）の熱可塑性樹脂よりも、高粘度の樹脂を使用するのが都合が良く、使用する樹脂のＭＦＲを２００ｇ／１０分未満とするのが都合良い。この点では５ｇ／１０分未満でも良い方向だが、繊維径５μｍ以下の繊維は作りにくくなる。
【００２６】
熱可塑性樹脂の融点（Ｔｍ：℃）は、凝集し絡み合い融着接着させた塊を作る上で、その繊維表面の過半を覆っている樹脂が（その融点をＴｍｓ：℃）低融点であることが好ましく、６０≦Ｔｍｓ＜１７０の範囲が都合が良い。融点が６０℃未満では融着接着しすぎ、制御が困難なため好ましくない。また１７０℃以上では、繊維の芯成分となる熱可塑性樹脂との組合せに制限を受けるので好ましくない。芯成分の熱可塑性樹脂（その融点をＴｍｃ：℃）の融点は、使用するメルトブロー設備の温度的制約があり、あまり高いものを用いることは好ましくない。実用的範囲では２７０℃未満とが適当である。なお、前記した繊維表面の過半を覆っている樹脂（その融点をＴｍｓ：℃）と芯成分樹脂の融点の関係については、Ｔｍｓ＋２０≦Ｔｍｃが好ましい。
【００２７】
本発明にいう熱接着とは、低融点の熱可塑性樹脂が融点以上に加熱されて溶融し接着することをいうが、加熱温度が低いときは低融点成分は繊維表面の形状を保ったまま接触する隣接繊維に融着する。加熱温度が融点より高くなるほど低融点成分は完全に溶融して接着点に凝集し、接着点を覆って隣接する繊維同士が一層強固に接着して一体化するようになる。
【００２８】
本発明のもう一つの特徴は、前記した様に用いる熱可塑性樹脂の溶融粘度が同じ樹脂でステープル繊維を製造する場合の樹脂の粘度範囲に一致している点にある。これは、本発明の不織布が、ステープル繊維の場合にはローラーカードなどの不織布化工程での各種制限を受けるより細い繊維を使用して不織布化することを主要な目的としていることにある。特にステープル繊維やマルチフィラメントなどでは紡糸中の繊維の融着が致命的であるが、この欠点を長所に用いて、特に繊維製造で融着接着し易い樹脂を鞘成分とする複合繊維を直接不織布化することをも主要な目的としている。
【００２９】
したがって、従来のメルトブロー不織布の様に、低粘度の樹脂を用いてひたすら細繊度化を狙うのではなく、ステープル繊維の腰や固さの特徴を持った繊維からなる不織布を作ることにあるため、本発明に用いる樹脂は、ステープル繊維を製造する場合と同様の溶融粘度となっているのである。しかし使用する樹脂の融点があまり高温になるとノズル直下のコンベアが過熱され不織布形成上好ましくない。この点が繊維を溶融紡糸するときとは違って設備上の制約をうけることになり、使用する熱風の温度を無闇に上げることができず、２７０℃という限定を設けたのであって、設備上の制約がなければさらに高い温度、例えば３５０℃でも可能である。
【００３０】
本発明に用いる樹脂の溶融流動性は、メルトフローレートで表現すると、５〜２００ｇ／１０分の範囲にあり、その測定温度は、２３０℃で十分溶けているか否かで区分けしたのであり、実際の溶融紡糸時の溶融温度での溶融流動性とは一致していない場合もある。樹脂によって、溶融紡糸に好ましい溶融流動性は異なり、ポリエチレンテレフタレートやポリメチルペンテンの最も好ましい溶融流動状態は、１００ｇ／１０分前後であり、ポリプロピレンは、これより低い。
【００３１】
以上の理由で、本発明に用いる熱可塑性樹脂は、従来のステープル繊維に用いられている樹脂を工夫すれば概ね都合良く用いることができるので、詳細は個々には言及しないが、融点が６０〜２７０℃の、ポリオレフィン樹脂、低融点エステル共重合体や脂肪属ポリエステルを含むポリエステル樹脂、ポリアミドやポリイミドなどのポノアミド樹脂、ポリカーボネート樹脂や融点を流動開始温度に読み替えた熱可塑性エラストマー樹脂が便利に使用でき、これらの混合物、ポリマーアロイやグラフト重合や低温プラズマ処理などによる改質樹脂も含む。また、融点が６０℃以上のものであれば例えば、融点が６０℃のＵＣＣ社の微生物崩壊性ポリエステルＴＯＮＥ（商品名）も不織布とした後の冷却に工夫がいるが本発明に都合良く用いられる。
【００３２】
特に、エレクトレット不織布向けには、ポリオレフィン樹脂が特に好ましく、エレクトレット素材としては、ポリブテン−１が特別好ましい。ポリブテン−１は結晶形態が軟質状態から硬くて脆い形態に経時変化する特異的な樹脂であるがポリプロピレンとの複合繊維として紡糸可能である。さらに低い融点の樹脂除外については、不織布の実用上の問題であって、別段理由はない。なお、本発明で言うポリプロピレンはエチレンなどの共重合体を含むことは言うまでもなく、ポリブテン−１も密度と融点を限定しているが、できるだけブテン−１過多なポリブテン−１がエレクトレット素材として好ましい意味であって用途によっては制限されない。特に繊維間融着しやすい樹脂としてはエチレンやプロピレンなどの共重合体や非晶質樹脂で、半溶融などの加熱下において柔軟性を示す樹脂が該当する。またプロピレンリッチのエチレンプロピレン共重合体やエチレン・オクテン共重合体や低密度ポリエチレンなどが好ましく用いられる。
【００３３】
本発明の嵩高なメルトブローン不織布は具体的には、融点が異なる２以上の上記熱可塑性樹脂成分からなり、低融点成分が繊維表面の大半を占めている複合繊維を構成繊維とするメルトブロー法により製造された不織布であって、構成繊維の複数本が部分的に凝集し融着した繊維塊が不織布中に多数存在して不織布表面に凸部を形成し、該繊維塊の周辺は繊維塊が存在していない部分より構成繊維の間隙が広がり繊維密度が低下していることを特徴とする、厚さ（μｍ）／目付（ｇ／ｍ2 ）が８以上である複合繊維不織布である。
この場合太繊維であるから部分的に凝集し熱接着した繊維塊となるのではなく、メルトブロー手法での設備と繊維化工程を吟味することで、繊維塊は繊度に無関係に意図的に作成でき、望ましくは熱接着し易い樹脂を鞘成分に用いることで目的の達成が容易となるだけであって、工夫すれば、ポリエチレンを鞘成分とする繊維も同様にできた。低圧損のフイルター用途向けには、１０μｍより太い繊維からなる層とフイルター機能を主体として持つ２０μｍより細い繊維からなる層の少なくとも２層から構成する不織布が都合良く、無論太い繊維層を構成する繊維は細い繊維層を構成する繊維より太いのは当然である。
【００３４】
上記複合繊維不織布はノズルからコンベアに直接メルトブローして集積したものを出口でコンベアベルトから剥離して得る。このときあらかじめコンベア上にスパンボンド不織布のような薄い基布を供給しつつこの上に複合繊維をメルトブローするとコンベアベルトからの不織布の剥離を滑らかにして都合がよい。また、基布はメルトブローン不織布を構成する繊維が延伸されておらず、繊維の配向結晶化が余り進行していないために繊維が脆くて低強力な点を補助するための、補強不織布としての役割と不織布の固さ、腰のつよさを増すためにも有効である。このような基布となる不織布は、スパンボンド不織布、メルトブローン不織布、スパンレース加工不織布、熱接着不織布、ニードルパンチ不織布、樹脂含浸接着不織布が都合良い。中でもスパンボンド不織布は、エレクトレット不織布とした時のコンベアーからの剥離性を向上させる役割を兼ねており、特にエレクトレット化した不織布には好都合である。このような基布不織布は、繊維素材に限定はないが、エァーフィルター用途では、繊維密度が粗いのが都合がよく、本発明のメルトブローン不織布がポリオレフィン樹脂でなる場合は、その接着性を考慮し、ポリオレフィン樹脂でなる不織布が好ましいのであり、廃棄処分する上でも特に好ましい。
【００３５】
エレクトレット加工する用途では、主としてフィルター用途のため、低圧損化の要求により、繊維径が１５μｍより太い繊維を使用することがよいが、より細い繊維でも用途により不都合ではない。また、両者に不織布を配したエレクトレット不織布は、吸塵用途のカーテンや壁掛けや壁紙を想定したものであり、本発明の複合繊維がポリオレフィン繊維の想定で熱接着による一体化を達成する目的で熱接着する面にポリオレフィン繊維を少なくとも部分的に配している不織布を使用している。
【００３６】
さらに嵩高化、すなわち高厚み化と低圧損化、そして基布との熱接着の簡易化を達成するため、基布に接する複合繊維不織布層の繊維を繊維径１０〜２００μｍの太繊度の繊維とし、基布との接着を熱接着だけでなく、太繊維の物理交絡効果も追加して、基布が受ける熱量を低減させて基布のフィルム化を抑制し、かつ凝集し絡み合い融着接着させた塊を厚くさせて、高厚み化を達成したのである。
【００３７】
基布に前記した太繊維の複合繊維不織布層を接着一体化させた複合不織布をエレクトレット加工すると、目付けが９０ｇ／ｍ2 を超えても強電界下で加工でき、さらに本発明の複合繊維不織布層を積層しても可能なことが判明した。また、太繊維の複合繊維不織布層を接着一体化させた複合不織布は、従来の複合不織布より腰があり、硬い不織布となり、プリーツ折り加工が容易で、形状保持効果も高くすることができた。
すなわち、異なる繊維径をもつ複合繊維を、繊維径が１５μｍ以上の繊維からなる不織布（基布）層の上に配するのである。第一段階は、基布の上に、繊維径（ｄ：μｍ）が１０＜ｄ＜２００である本発明の太複合繊維を配するのであるが、繊維径が５０〜１０μｍの太複合繊維からなる層を、メルトブローノズルと基布の間隔を近付けて噴出して目付けが５〜１５ｇ／ｍ2 となるように集積させ、次いで、所望の繊維径の太複合繊維を集積するのが最も好ましい。太複合繊維層を構成している太複合繊維は、従って複数種の繊維径の繊維の集積であってもなんら不都合はない。
【００３８】
ノズルと基布の間隔は５〜２５ｃｍ程度にするとよい。これは通常のメルトブロー紡糸工程におけるより近い距離である。近付けて噴出して集積する理由は、基布へ太複合繊維が浸入して、太繊維で物理的交絡するのを容易とし、基布繊維と該太繊維の融着接着効果を高めるためである。しかし、ノズルと基布の間隔は、基布がメルトブロー紡糸の熱風で溶けない間隔に設定するのは当然であるが、長時間運転を続けると、循環するコンベアベルトの温度が上昇し、基布の一部が溶融またはフィルム化する問題が発生し好ましくない。この現象を防止するには、前記した、目付けが５〜１５ｇ／ｍ2 の繊維径が５０〜１０μｍの太繊維を用いる範囲が最も都合が良い。目付けが５ｇ／ｍ2 未満では、基布との接着性が弱く、１５ｇ／ｍ2 を超えると溶融またはフィルム化する問題が発生しやすい。該太繊維の繊維径も５０μｍを超えると基布を構成する繊維の部分溶融を生じやすく、１０μｍ未満であると基布表面への繊維集積効果が大きく、基布層への太繊維の浸入が少なくて太繊維の物理的交絡効果が減じられてあまり好ましくない。
【００３９】
本来、太繊維ほど嵩高化、低圧損化および不織布の高硬さ化（不織布の高腰性と高プリーツ折り性が良い）に良いのであり、必要に応じて、より太い繊維をこれらの上に、繊維間を繊維の表面の過半を占めている低融点樹脂で融着接着または溶融接着させながら積層して接着一体化するのが極めて都合が良い。
フイルター用途に本発明の複合不織布を用いる場合、上記した基布と太複合繊維の集積層の上に、塵埃を主として捕集する機能を求める、本発明のより細い複合繊維層を積層してフイルターとしての機能を持たせる。そのより細い複合繊維の繊維径（ｄ：μｍ）は０．３＜ｄ＜２０であり、目的によって繊維径を任意に選択する。
【００４０】
なお、本発明でいう繊維径は、数平均の繊維径をいい、本発明の不織布は、熱接着性複合繊維を使用している、そして、恣意的に部分的に融着接着させているため、繊維径のばらつきや分布が広く、顕微鏡観察によって繊維径を割り出したため、数平均で記載した。融着接着した塊や繊維束は１本として計測した。
【００４１】
なお、本発明での複合メルトブロー繊維は、特に凝集し融着接着した塊を散在させる方が凹凸方式による嵩高化には有利であり、太繊維を使用する場合は、複数回に分けて繊維集積するのが特に好ましい。また、細繊維層にあっても、エァーフィルター用途を想定するなら、目付けむらを回避するため、前記と同様に複数回に分けて繊維集積するのが特に好ましい。また、これらの繊維集積において、メルトブロー手法では繊維が一定方向へ揃い易いので、各層毎にできるだけ交差する様に積層するのが好ましく、本発明では、設備にこの点が配慮してある。
上記した様に個々の層の必要目付けを考慮した上で、本発明の不織布の目付けは用途によるが、３０〜４００ｇ／ｍ2 が好ましく、４００ｇ／ｍ2 を超えると熱風の貫通状況が悪くて、３０ｇ／ｍ2 未満では、必要な各構成層の目付けが確保できないので都合が良くない。プリーツ折りフイルター用途では、その剛性を考慮すると６０ｇ／ｍ2 以上が好ましい。
【００４２】
本発明の複合不織布は使用する繊維を選択し様々な用途に応用することができる。例えばポリブテン−１／ポリプロピレンの複合繊維を中層とした両面が、界面活性剤などの親水性物質が付着していないオレフィン不織布で占められたエレクトレット不織布で、集塵カーテンなどに都合が良い不織布にも関する。
【００４３】
また、本発明のメルトブロー不織布本体は炎が当たると速やかに孔が開く現象を生じ、難燃性に優れているが、ポリプロピレンスパンボンド不織布と張り合わせした複合不織布は、メルトブロー不織布側から炎を当てると良難燃性だが、スパンボンド不織布側からでは、難燃性に劣る結果を得ており、スパンボンド不織布を構成するポリプロピレン樹脂に、チバ・スペシャリティ・ケミカルズ社の難燃効果剤フレムスタブＣＧＬ−１１６を少なくとも０．５重量％添加してスパンボンド不織布とした本発明のメルトブロー複合不織布は、どちらからの面から炎を当てても常に、難燃評価法ＪＩＳ．Ｌ１０９１、Ａ−１法で難燃３級を得ることができる様になるので、さらにエァーフィルター素材として最適となる。
前記した難燃効果剤ＣＧＬ−１１６は、ポリプロピレンの通常の耐候安定剤であるハルス系安定剤の誘導体であり、該ハルス系安定剤や他の安定剤との併用でも、環境ホルモンや有害物質を含まないので大変環境に優しい。
【００４４】
本発明の実施の形態について図に基づいて説明する。図１は本発明による複合不織布の構成繊維である複合繊維の断面形状の例を示す図である。図１のＡは一般に猫目と称される芯成分である断面形状で、高融点成分（１）が楕円形でその周囲を鞘成分である低融点成分（２）が取り囲んでいる構造である。Ｂは同心型の芯鞘構造で芯が高融点成分、鞘が低融点成分である。Ｃは高融点成分が低融点成分によって挟まれた三層構造である。
【００４５】
図２は本発明の複合繊維不織布の側方断面を拡大した図である。複合繊維が部分的に熱接着している部分の繊維塊（３）の周囲は複合繊維は太い複合繊維（４）も細い複合繊維（５）も繊維の間隙が広く繊維密度が低く嵩高で不織布の凸部を形成している。これに対し繊維塊と繊維塊の中間部分は繊維密度が高い部分（６）になっている。
【００４６】
次に本発明の効果実施例と比較例で具体的に説明する。なお、本発明の実施の１形態である鞘成分をポリブテン−１とし、芯成分をポリプロピレンとする複合繊維のメルトブロー不織布で、主に説明するが、他の形態の複合繊維不織布および複合不織布も実施例を参考にすれば、同様に容易に作ることができることは、言うまでもない。
【００４７】
【実施例】
本発明のメルトブロー手法によって繊維化された複合繊維は、２台の押出機より個々の熱可塑性樹脂を押出し、ギャーポンプによって定量供給して、複合繊維を形成できる７０ｃｍ弱の幅の８５０ホールの複合ノズルを用いて、オリフィスの列から高速加熱気流中に吐出すると同時に、該気流で細長化して基本的に連続している繊維とし、吸引設備が具備されたネットコンベアー上に集積するのであるが、該コンベアー上に１４０℃で予め熱処理させたポリプロピレンスパンボンド不織布を位置させ、該不織布上に、平均繊度が６〜１０ｄＴｅｘ（２３〜３８μｍφ）の太複合繊維を１５ｇ／ｍ2 の目付けで集積し、ネットコンベアーの進行角度を一回毎に変化させて所望の目付けの太繊維または細繊維をそれぞれ複数層重ねて積層して本発明の複合繊維不織布を試作した。なお、各層は少なくとも３０度の角度で交差させて集積した。
本発明に用いた樹脂は、表１の通りで、ＰＰはポリプロピレン、ＰＢはポリブテン−１（三井化学タフマー、密度Ｄ：０．９２ｇ／ｃｍ3 ）、ＰＥはポリエチレン、ＰＴはポリエチレンテレフタレート（常法の限界粘度ＩＶ値が０．６４の樹脂を使用）、ＰＭはポリメチルペンテン（三井化学ＴＰＸ）、ＥＰはプロピレン過多のエチレン・プロピレン共重合体を使用した。なお鞘と芯成分の複合比は１：１で、溶融流動性のＭＦＲは、測定温度がＰＴとＰＭは２９０℃で他は２３０℃での値で、単位はｇ／１０分である。Ｑ値は重量平均分子量／数平均分子量の比である。
【００４８】
【表１】
（実施例１〜７、比較例１〜２） 本発明の複合繊維メルトブロー不織布は、表１の樹脂を用い、前記の工程で表２の条件で不織布化した。なお紡糸温度とはノズル温度のことであり、同温度の高圧熱風を用いて噴出させ、これを噴出熱風量の５倍以上の吸引量で吸引して、１５ｇ目付けで約７ｄＴｅｘのスパンボンド不織布の上に集積して、実施例と比較例の複合不織布を得た。
表２中の繊径は、数平均の繊維径μｍで、融着繊維は除外しており、各繊維層は少なくとも２回の集積回数のもので、その総目付けｇ／ｍ2 で表示し、厚みはＪＩＳ−Ｌ−１９１３−６．１．２Ａ法により測定した。
比較例１は、実施例のノズルを３ｍｍピッチのノズルとし、凝集して絡み合い熱接着した繊維塊の少ない不織布としたものである。
各実施例、比較例の使用した樹脂成分、複合繊維不織布の嵩高さ等を表２に示す。
【００５０】
（実施例８） 実施例１で、ポリプロピレンスパンボンド不織布を使用せず、本発明の複合繊維メルトブロー不織布を積層したものを作成した。（見かけ）厚みは実施例１と同じであった。
（実施例９） 実施例２の不織布と２ｄＴｅｘ、目付け４０ｇ／ｍ2 のポリプロピレンスパンボンド不織布を、１４０℃の熱風加工機で、バーを用いて擦る様に圧迫しながら張り合わせし、その後実施例１と同様にしてエレクトレット熱加工してエレクトレット不織布とした。大気塵を拡散させたボックス内に入れると、著しく大気塵を吸着して、表面のスパンボンド不織布が灰色ぽくなった。
（実施例１０）目付けが６０ｇ／ｍ2 の６ｄＴｅｘレーヨンスパンレース加工不織布を、６５０〜７００℃の無酸素下で焼成して得た活性炭素繊維不織布を、実施例１で使用した７ｄＴｅｘのスパンボンド不織布に乗せ、その上から、２ｄＴｅｘのレーヨン繊維の目付け３０ｇ／ｍ2 のウエッブを乗せて、スパンレース加工して、該レーヨン繊維で交絡一体化させたスパンレース加工不織布とし、該不織布を実施例１でのスパンボンド不織布の替わりとして、スパンボンド不織布層を上とし、実施例１と同様にしてメルトブロー不織布を積層し、複合不織布とした。該複合不織布は、少なくとも硫化水素を捕集する能力を保持していた。
【００５１】
【表２】
実施例１〜７で得られた不織布を折り機かけてプリーツ折り加工したところギアロールの掛り具合がよく、順調にプリーツ折りができた。比較例１、２の平滑な不織布は掛りにくく作業性が悪かった
実施例、比較例の得られた不織布の内、鞘成分にＰＢ用いた複合繊維の不織布は、１２０℃の熱風加工機内外に針を一定間隔で埋め込んだ直流高電圧印加装置で、加熱下と急冷下、共に、９Ｋｖのマイナス直流印加し、静電気をアースして除いたエレクトレット不織布とした。これらを使用して大気塵の０．５μｍ粒子の捕集効率とその時の圧損を測定した。表２にその結果を示す。
なお、捕集効率の測定流速は５．３ｃｍ／ｓでＪＩＳ−Ｂ−９９０８に準拠し、フイルターユニットの替わりに、各実施例の不織布を装着し、濾過面を１００ｍｍφとして測定した。
各実施例の嵩高さの効果は圧損の低さに現れている。
【００５３】
（実施例１１）実施例１のポリプロピレンスパンボンド不織布を構成するポリプロピレン樹脂にチバ社の耐候安定剤９４４を０．１重量％、難燃効果剤ＣＧＬ１１６を１．５重量％、燐系安定剤１６８を０．３重量％添加した複合不織布は常に良難燃性を示した。
【００５４】
【発明の効果】
本発明の１つは、従来からステープル繊維で使用されてきた熱可塑性樹脂を用いた複合繊維をメルトブロー繊維化手法を用いて、直接不織布化した点にあり、ステープル繊維やマルチフィラメント繊維などの従来の繊維化手法では、極めて困難な問題となっていた、融着し易い熱可塑性樹脂を積極的に利用できる点にあり、特に好ましいのは前記した融着し易い樹脂を繊維表面に用いた複合繊維であるが、この融着現象を積極的に利用して、繊維の噴出中に繊維の部分融着を起こさせ、凝集して絡み合い融着接着した塊を散在させて、不織布面に凹凸を生じさせ、見かけの厚みを増やすことで、従来の単一繊維のメルトブロー不織布では達成しえなかった厚みのある不織布としたのである。この嵩高化により、従来はポリエステル樹脂接着不織布にメルトブロー不織布を接着した構成のエァーフィルターを主として原材料としていた、プリーツ折り機にも、問題なく掛かるエァーフィルター素材とすることができたのである。また複合不織布にあっては樹脂含浸処理することにより不織布相互の接着性を高め、剥離しやすい問題点も解消Ｄされる。
【００５５】
また、焼却などの廃棄処分では、煤のでるポリエステル素材を全く使わない、オールポリオレフィン樹脂製のエァーフィルター素材を提供できる様になったのである。しかしながら、ポリオレフィン樹脂は電気絶縁性が高く、従来の様に、単にメルトブロー不織布を積層しても、その電気絶縁性のため、十分なエレクトレット加工ができない新たな問題を生じたが、従来手法で積層したメルトブロー不織布では不十分なエレクトレット加工しかできなかった目付けでも、本発明のメルトブロー不織布は、格段にエレクトレット特性を付与できる様になし得た。
本発明のオールポリオレフィン樹脂製のエァーフィルター素材は、特に、廃棄処分が容易で、素材として、環境ホルモンや他の有害物を一切含まず、たとえ、火災に遭遇しても、煤や、塩化水素などの有害ガスを発生しないので、人と環境に配慮した不織布素材として好適である。
【図面の簡単な説明】
【図１】図１のＡ、Ｂ、Ｃは本発明の複合不織布を構成する複合繊維の断面図の例である。
【図２】本発明の複合不織布の側方断面図の拡大図である。
【符号の説明】
１ 高融点成分
２ 低融点成分
３ 繊維塊
４ 太い複合繊維
５ 細い複合繊維
６ 繊維密度が高い部分[0001]
BACKGROUND OF THE INVENTION
The present invention generally uses a thermoplastic resin having a melt viscosity for producing staple conjugate fibers to produce a finer or thicker conjugate fiber having the same physical properties as the staple conjugate fiber, such as the waist of the fiber. When using a staple composite fiber to form a nonwoven fabric, a composite that does not use a roller card or the like that restricts the fineness, and at least a fiber assembly such as a directly opened fiber web or a melt bonded and integrated nonwoven fabric The present invention relates to a composite fiber nonwoven fabric that has been made into a fiber and a nonwoven fabric by a melt-blowing method capable of producing fibers, and a composite nonwoven fabric to which these are applied. In the present invention, particularly in the production of staple fibers, there has been a problem of melt bonding between the spun fibers at the time of spinning, and a composite fiber using a resin having a low melting point, a low tackiness, and a soft surface hardness can be freely used. Non-woven fabrics containing fine fibers that required technology to make a non-woven fabric because the fibers are thin, and composite fibers using a hard and brittle resin or a resin that has poor spinnability and cannot be made alone The present invention relates to these composite fiber nonwoven fabrics and composite nonwoven fabrics to which these are applied. Furthermore, adhesive treatment nonwoven fabrics and electret nonwoven fabrics for applications such as electret nonwoven fabrics that dislike fiber treatment agents such as surfactants, and materials for air filters such as building air conditioning filters, dust-absorbing curtains and mask materials The present invention relates to a non-woven fabric that can be easily folded and molded as a filter.
[0002]
[Prior art]
Melt blown nonwoven fabrics composed of composite fibers composed of two different components are disclosed in various known documents such as JP-A-5-179511, JP-A-5-214655, JP-A-5-263307, and JP-A-2001-98453. These all relate to a technique for obtaining a nonwoven fabric by melt blowing two thermoplastic resins having different melting points.
[0003]
[Problems to be solved by the invention]
The present inventor proposed an electret non-woven fabric in Japanese Patent Application Laid-Open No. 2001-98453, but encountered a problem that the thickness was thin and the pleat could not be folded with a rotary pleat folding machine, and the pressure loss of the non-woven fabric was high contrary to expectations. The current melt blown nonwoven fabric is composed of a single component, so most of the nonwoven fabric is not self-bonded and adhesive, has a problem with lint-free properties, and is low in volume and thin like paper. It was only. As described above, the nonwoven fabric of the present invention composed of fibers made by the melt blow method is mainly designed for use in pleated filters that require bulk and firmness. One of the objects is to provide a non-woven fabric composed of fibers made by melt blowing. In electret nonwoven fabrics made entirely of polyolefin resin, the insulation resistance is large, and when the basis weight of the nonwoven fabric is increased to increase the thickness, the basis weight is 90 g / m. 2 If it exceeds, the penetration of the electric field suddenly becomes poor, the electret imparting effect suddenly decreases, and it is also found that it is impossible to make an electret filter with high collection efficiency. became. Moreover, in the electret nonwoven fabric which affixed the impregnated polyester fiber nonwoven fabric to the base fabric, the basis weight is 120 g / m. 2 However, electretization was easy, and the problem was particularly serious with electret non-woven fabrics that were all made of polyolefin resin. In view of such a problem, a commercially available melt blown nonwoven fabric was investigated, and it was found that the constituent fibers were accumulated in a fairly regular order along the jet blown air flow of the melt blow. That is, it is obvious that the thinner the fibers constituting the nonwoven fabric, the thinner the nonwoven fabric, and the higher the pressure loss (pressure loss), and this method cannot achieve the bulkiness and low pressure loss of the nonwoven fabric. In the above prior art, the melt blown nonwoven fabric is manufactured so as to be laminated as uniformly as possible on the conveyor belt by hot air from the nozzle, so that the resulting nonwoven fabric tends to be smooth and paper-like. Such a nonwoven fabric has a drawback that it is difficult to be applied to a gear roll of a pleat folding machine, has poor workability, and has a disadvantage that the bulkiness of the nonwoven fabric is small and the pressure loss increases when trying to increase the collection efficiency as a filter. Also, since polybutene-1 resin is harder than polypropylene resin, the polypropylene / polybutene-1 composite fiber melt-blown nonwoven fabric of the present invention is a nonwoven fabric that is much harder and lower than polypropylene-only melt-blown nonwoven fabric, but is used as a pleated folding filter. In addition, there was a problem of making the nonwoven fabric harder and lower. In addition, when making an electret nonwoven fabric made entirely of polyolefin resin, using a polypropylene spunbond nonwoven fabric as a base fabric, the nonwoven fabric in which the polypropylene / polybutene-1 composite fiber of the present invention is sprayed and thermally bonded to the spunbond nonwoven fabric, When operating for a long period of time, some non-woven fabrics that are heat-bonded and others that are not bonded and integrated, but non-woven fabrics that are all heat-bonded, the base fabric melts or forms a film that is partially continuous in the longitudinal direction. Phenomenon occurs, and the pressure loss of the part increases, and quality unevenness such as air permeability in the width direction and dust collection efficiency occurs. In addition, the non-woven fabric of the present invention in which the base fabric is an impregnated PET non-woven fabric has a problem that the adhesive strength with the PET non-woven fabric is weak and is easily peeled off. The non-woven fabric of the present invention is a non-woven fabric composed of a composite fiber produced by a melt-blowing method for the most part of its constituent layers, is bulky, has little fiber dropout during use as a filter, and has a pressure loss even during long-term use. The object is to solve the above-mentioned problems because it is small and sufficient electretization is possible.
[0004]
[Means for Solving the Problems]
The conventional melt-blowing method is based on a method in which a molten resin is ejected from a nozzle in a bowl shape and accumulated on a conveyor as fibers, and then the fibers are thermally bonded to form a melt-blown nonwoven fabric. In the period from when the squirt is dropped to the conveyor, the adjacent fibers are partially brought into contact with each other to actively generate a mass in which the fibers are agglomerated and entangled and thermally bonded. By realizing the uneven distribution, a new meltblown nonwoven fabric was obtained and the above-mentioned problems could be solved.
The melt-blown nonwoven fabric obtained in this way has a large number of fiber lumps scattered in the nonwoven fabric, the thickness of the nonwoven fabric is increased by that amount, and the periphery of the fiber lumps is between the collected fibers. The structure creates a large gap. Furthermore, by collecting fibers from the top, it is possible to create a three-dimensional accumulation condition in the thickness direction and actively perform fiber accumulation to lower the density. As a result, it is possible to widen the inter-fiber gap and improve fluid permeability. It was. In other words, the effect of reducing the pressure loss was produced and the bulkiness was also achieved.
[0005]
That is, the present invention comprises two or more thermoplastic synthetic resins having different melting points, The melting point (Tm: ° C.) of each thermoplastic synthetic resin satisfies 60 ≦ Tm <270, and its melt fluidity melt flow rate (MFR: g / 10 minutes; measurement temperature is 230 ° C., T <200 when Tm ≦ 200. 290 ° C. when Tm, weight is 2.169 Kg, according to JIS-K-6760), but 5 <MFR <200, A non-woven fabric produced by a melt-blowing method in which a low-melting-point component occupies most of the fiber surface as a constituent fiber, A fiber lump in which a plurality of adjacent fibers of the composite fiber are brought into contact with each other in the air during ejection and the fibers are aggregated and thermally bonded is partially and locally unevenly distributed in the nonwoven fabric. A convexity is formed on the surface of the nonwoven fabric, and the periphery of the fiber lump is characterized by the fact that the interval between the constituent fibers is wider than the part where the fiber lump is not present and the fiber density is lowered. G / m 2 ) Is a composite fiber nonwoven fabric having 8 or more.
[0006]
The composite fiber has an average fiber diameter (d: μm) of 0.3 <d <200, and each of a plurality of constituent thermoplastic resin components has a melting point (Tm: ° C.) of 60 ≦ Tm <270, and its melt fluidity. Melt flow rate (MFR: g / 10 min; measurement temperature is 230 ° C. when Tm ≦ 200, 290 ° C. when 200 <Tm, weight is 2.169 Kg, according to JIS-K-6760) is 5 <MFR A thermoplastic synthetic resin of <200 is preferred.
[0007]
The thermoplastic resin component of the composite fiber has a low melting point component density (D: g / cm Three ) Is 0.905 ≦ D <0.930 and the melting point (Tms: ° C.) is 115 <Tms <130, and the other is preferably polypropylene.
[0008]
Furthermore, the present invention provides at least a low melting point component of the composite fiber constituting the composite fiber nonwoven fabric in which a surface nonwoven fabric layer made of fibers having a fiber diameter of 15 μm or more is disposed on at least one side of the composite fiber nonwoven fabric composed of polybutene-1 and polypropylene. It is a composite nonwoven fabric integrated by thermal bonding.
[0009]
One of the preferred embodiments of the composite nonwoven fabric has a basis weight of 30 to 400 g / m. 2 It is a composite nonwoven fabric.
[0010]
The surface non-woven fabric layer is preferably a spunbonded non-woven fabric made of one or more resins among a homopolymer mainly composed of propylene and a copolymer mainly composed of propylene.
[0011]
The surface non-woven fabric layer is a non-woven fabric in which fibers made of polyethylene terephthalate (PET) resin are impregnated with resin and bonded and integrated with the resin, and at least one surface of which fibrous fixed matter made of polyolefin resin is scattered. It is preferable that the composite fiber nonwoven fabric of the present invention is arranged on the surface, and the composite nonwoven fabric is preferably formed by fusion and integration. As this fibrous fixed matter, for example, a resin-impregnated nonwoven fabric made of polypropylene spunbonded nonwoven fabric or the like is preferable. As the resin, for example, an acrylic resin or the like is applied. With such a configuration, the composite nonwoven fabric of the present invention can be a composite nonwoven fabric imparted with adhesion by the resin and excellent in peel strength between the nonwoven fabrics.
[0012]
Furthermore, in the present invention, the composite fiber composed of polybutene-1 and polypropylene has an average fiber diameter (d: μm) of 0 on the composite nonwoven fabric in which the average fiber diameter (d: μm) is 10 <d <200. A composite nonwoven fabric in which the composite fiber nonwoven fabric having a composite fiber of 3 <d <20 as a constituent fiber is arranged, and the layers between the nonwoven fabrics are thermally bonded and integrated by a low melting point component of the composite fiber.
[0013]
One of the preferred embodiments of the composite nonwoven fabric has a basis weight of 60 to 400 g / m. 2 It is a composite nonwoven fabric.
[0014]
One of the preferred embodiments of the present invention is a composite nonwoven fabric in which the composite nonwoven fabric is electret-processed, and at least a composite fiber composed of polybutene-1 and polypropylene is electretized.
[0015]
Moreover, one of the preferable aspects of this invention is that the surface nonwoven fabric layer is comprised by the polypropylene fiber or polyethylene fiber to which hydrophilic chemical substances, such as surfactant, are not adhered, and this surface nonwoven fabric layer is distribute | arranged on both surfaces. A composite fiber nonwoven fabric composed of the above polybutene-1 and polypropylene, which is a composite nonwoven fabric integrated by thermal bonding with at least a low melting point component of the composite fiber constituting the composite fiber nonwoven fabric, and is electretized It is.
[0016]
One of the preferred embodiments of the present invention is a composite fiber comprising the composite fiber nonwoven fabric in which a surface nonwoven fabric layer composed of fibers having a fiber diameter of 15 μm or more is disposed on at least one surface of the composite fiber nonwoven fabric made of polybutene-1 and polypropylene. At least the low melting point of the composite fiber is obtained by laminating a hydrophilic fiber layer made of polypropylene fiber and rayon fiber having a fiber diameter of 5 μm or more on the composite fiber nonwoven fabric surface side of the composite nonwoven fabric integrated by thermal bonding with at least a low melting point component of It is a composite nonwoven fabric that is integrated and electretized by thermal bonding with the above components.
[0017]
One of the preferred embodiments of the present invention is a composite fiber comprising the composite fiber nonwoven fabric in which a surface nonwoven fabric layer composed of fibers having a fiber diameter of 15 μm or more is disposed on at least one surface of the composite fiber nonwoven fabric made of polybutene-1 and polypropylene. A laminated nonwoven fabric consisting of three layers of a rayon fiber layer, an activated carbon fiber layer, and a polypropylene spunbond nonwoven fabric layer is formed on at least one surface of the composite nonwoven fabric integrated by thermal bonding with at least a low melting point component of the composite fiber according to the low melting point component of the composite fiber. It is a composite nonwoven fabric that is integrated by thermal bonding and is electretized.
[0018]
Moreover, one of the preferable aspects of this invention is the said composite nonwoven fabric in which the fiber of nonwoven fabric layers other than a melt blown nonwoven fabric is flame-retarded.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The composite fiber constituting the nonwoven fabric of the present invention is composed of two or more thermoplastic resin components having different melting points. Preferably, the two components as shown in FIG. This is a fiber having a cross-sectional structure like a three-layer type separated into two, and the low melting point component occupying most of the fiber surface. In addition, multi-core type, three-layer type, and the fiber cross-section that is divided into at least a plurality of components and divided by other components are split fiber types such as mandarin orange type and windmill type, and the fiber shape is circle or ellipse Although it is basically a circular shape, there may be a variant with a rounded corner.
[0020]
The thermoplastic resin that forms such a composite fiber is a melt-viscosity melt flow rate (MFR: g / 10 minutes; the measurement temperature is Tm ≦ A thermoplastic synthetic resin in which 5 <MFR <200 is 230 <0> C at 200, 290 <0> C when 200 <Tm, weight is 2.169 Kg, according to JIS-K-6760). Using a thermoplastic resin having such melt fluidity, adjacent fibers of a composite fiber spun from a nozzle are partially brought into contact with each other during ejection to form a nonwoven fabric having a fiber mass in the structure. .
[0021]
In the process of bringing adjacent fibers of the composite fiber spun from the nozzle into contact with each other in the air during jetting to generate a lump that is partially and locally unevenly agglomerated, entangled and fused and bonded. When the interval between the discharge holes (the distance between the centers of the circular discharge holes) is about 3 mm, it is impossible to make the fibers adjacent to each other between the heights of about 5 to 20 cm up to the conveyor. .
[0022]
The inventors of the present invention have devised a nozzle having many discharge holes, and succeeded in generating an agglomerated, entangled, fused and bonded mass by making the discharge hole interval less than 1 mm. That is, when making a thick fiber nonwoven fabric with a large amount of aggregated and entangled fusion bonded, it is better to increase the discharge amount and slightly reduce the hot air flow rate, and a nonwoven fabric with less aggregated and entangled fused bonded mass Can be achieved by reducing the discharge amount and increasing the hot air flow velocity. This utilizes the ballast effect of the resin. The composite fibers spun in this way are substantially continuous, and a plurality of them are partly fused to form a fused part, and are continued as a single composite fiber.
[0023]
The fiber diameter of the composite fiber of the present invention is such that the fiber diameter varies between the fused part and the non-fused part, and the thick part is generally less than 200 μm, and substantially continuous is the fiber for some individual reason. Unless it is broken, it means that the production condition is not intended to be broken.
[0024]
By producing a melt blown nonwoven fabric in this way, a nonwoven fabric having a thickness of 20 to 100% was obtained from a melt blown nonwoven fabric having the same basis weight using the same thermoplastic resin by a conventional melt blow method.
In the present invention, the thickness of the nonwoven fabric was measured by the JIS L-1913-6.1.2A method.
[0025]
In the present invention, it is convenient to use a high-viscosity resin rather than a high-flow (low-viscosity) thermoplastic resin, and it is convenient to set the MFR of the resin to be used to be less than 200 g / 10 minutes. In this respect, the direction may be less than 5 g / 10 minutes, but it is difficult to produce fibers having a fiber diameter of 5 μm or less.
[0026]
The melting point (Tm: ° C) of the thermoplastic resin is such that the resin covering the majority of the fiber surface (the melting point is Tms: ° C) has a low melting point when creating a mass that is agglomerated, entangled and fused and bonded. Is preferable, and a range of 60 ≦ Tms <170 is convenient. If the melting point is less than 60 ° C., it is not preferable because it is too fused and difficult to control. Further, if the temperature is 170 ° C. or higher, the combination with the thermoplastic resin that is the core component of the fiber is limited, which is not preferable. The melting point of the core component thermoplastic resin (whose melting point is Tmc: ° C.) is not preferable because it has a temperature restriction of the melt blow equipment used. In the practical range, it is appropriate to be less than 270 ° C. The relationship between the resin covering the majority of the fiber surface (the melting point is Tms: ° C.) and the melting point of the core component resin is preferably Tms + 20 ≦ Tmc.
[0027]
The thermal bonding referred to in the present invention means that a thermoplastic resin having a low melting point is heated to a melting point or higher and melts and adheres, but when the heating temperature is low, the low melting point component is in contact with the fiber surface being kept in shape. Fused to adjacent fibers. As the heating temperature becomes higher than the melting point, the low melting point component is completely melted and aggregates at the bonding point, and the adjacent fibers covering the bonding point are more firmly bonded and integrated.
[0028]
Another feature of the present invention is that the thermoplastic resin used as described above has a melt viscosity that matches the viscosity range of the resin when staple fibers are produced from the same resin. This is because the main purpose of the nonwoven fabric of the present invention is to form a nonwoven fabric using finer fibers that are subject to various limitations in the nonwoven fabric forming process such as a roller card in the case of staple fibers. Especially for staple fibers and multifilaments, the fusion of fibers during spinning is fatal. However, this disadvantage is used as an advantage, and a composite fiber with a sheath component made of a resin that is easy to fuse and bond in fiber production is directly non-woven. The main purpose is to make it easier.
[0029]
Therefore, unlike conventional melt blown nonwoven fabrics, rather than aiming for finer fineness using a low-viscosity resin, it is to create a nonwoven fabric consisting of fibers with the characteristics of stiffness and stiffness of staple fibers. The resin used in the present invention has the same melt viscosity as that for producing staple fibers. However, if the melting point of the resin used is too high, the conveyor just below the nozzle is overheated, which is not preferable for forming a nonwoven fabric. Unlike this, when the fiber is melt-spun, there are restrictions on the equipment, and the temperature of the hot air used cannot be raised without darkness. If there is no limitation, a higher temperature, for example, 350 ° C. is possible.
[0030]
The melt fluidity of the resin used in the present invention is in the range of 5 to 200 g / 10 minutes when expressed in terms of the melt flow rate, and the measurement temperature is divided according to whether or not it is sufficiently melted at 230 ° C. The melt fluidity at the melt temperature at the time of melt spinning may not be consistent. The melt fluidity preferred for melt spinning varies depending on the resin, and the most preferred melt fluid state of polyethylene terephthalate or polymethylpentene is around 100 g / 10 minutes, and polypropylene is lower than this.
[0031]
For the above reasons, the thermoplastic resin used in the present invention can be used generally conveniently if the resin used in the conventional staple fiber is devised. 270 ° C polyolefin resin, polyester resin including low melting point ester copolymer and aliphatic polyester, polyamide resin, pomamide resin such as polyamide and polyimide, polycarbonate resin and thermoplastic elastomer resin with melting point read as flow start temperature can be conveniently used In addition, a mixture thereof, a polymer alloy, a modified resin by graft polymerization, a low temperature plasma treatment, or the like is also included. In addition, if the melting point is 60 ° C. or higher, for example, UCC microbial disintegrating polyester TONE (trade name) having a melting point of 60 ° C. is devised for cooling after it is made into a nonwoven fabric, but it is conveniently used in the present invention. .
[0032]
In particular, polyolefin resins are particularly preferred for electret nonwoven fabrics, and polybutene-1 is particularly preferred as the electret material. Polybutene-1 is a specific resin whose crystal form changes over time from a soft state to a hard and brittle form, but can be spun as a composite fiber with polypropylene. Further, the exclusion of the resin having a lower melting point is a practical problem of the nonwoven fabric, and there is no other reason. In addition, it is needless to say that the polypropylene referred to in the present invention includes a copolymer such as ethylene, but polybutene-1 also has a limited density and melting point. However, polybutene-1 containing as much butene-1 as possible is preferable as an electret material. However, it is not limited depending on the application. In particular, a resin that is easily fused between fibers is a copolymer or an amorphous resin such as ethylene or propylene, and a resin that exhibits flexibility under heating such as semi-melting. Further, propylene-rich ethylene-propylene copolymer, ethylene-octene copolymer, low-density polyethylene and the like are preferably used.
[0033]
Specifically, the bulky melt blown nonwoven fabric of the present invention is produced by a melt blow method in which a composite fiber is composed of two or more thermoplastic resin components having different melting points and the low melting point component occupies most of the fiber surface. A large number of fiber lumps in which a plurality of constituent fibers are partially agglomerated and fused to form a convex portion on the nonwoven fabric surface, and there are fiber lumps around the fiber lumps. Thickness (μm) / weight per unit area (g / m) 2 ) Is a composite fiber nonwoven fabric having 8 or more.
In this case, thick fibers are not partly agglomerated and heat-bonded fiber mass, but by examining the equipment and fiberization process using the melt-blowing method, the fiber mass can be created intentionally regardless of the fineness. The use of a resin that is easily heat-bonded as a sheath component only makes it easy to achieve the object, and if devised, a fiber having polyethylene as the sheath component could also be obtained. For low-pressure loss filter applications, a non-woven fabric composed of at least two layers of a layer composed of fibers thicker than 10 μm and a layer composed mainly of fibers smaller than 20 μm mainly having a filter function is convenient. Of course, fibers constituting a thick fiber layer Is naturally thicker than the fibers that make up the thin fiber layer.
[0034]
The composite fiber non-woven fabric is obtained by directly melt-blowing from a nozzle to a conveyor and accumulating it and peeling it from the conveyor belt at the outlet. At this time, when a thin base fabric such as a spunbond nonwoven fabric is supplied on the conveyor in advance and the composite fiber is melt blown thereon, it is convenient to smoothly peel the nonwoven fabric from the conveyor belt. In addition, the base fabric is a non-stretched fiber that forms the meltblown nonwoven fabric, and the orientation crystallization of the fiber has not progressed so much that the fiber is brittle and assists the low strength point. It is also effective for increasing the stiffness of the nonwoven fabric and the waist. As the nonwoven fabric to be such a base fabric, a spunbond nonwoven fabric, a meltblown nonwoven fabric, a spunlace processed nonwoven fabric, a heat bonded nonwoven fabric, a needle punched nonwoven fabric, and a resin impregnated bonded nonwoven fabric are convenient. Among them, the spunbond nonwoven fabric also serves to improve the peelability from the conveyor when it is an electret nonwoven fabric, and is particularly advantageous for electretized nonwoven fabrics. Such a non-woven fabric is not limited to a fiber material, but for air filter applications, it is convenient that the fiber density is coarse. When the melt blown non-woven fabric of the present invention is made of a polyolefin resin, its adhesiveness is taken into consideration. A non-woven fabric made of polyolefin resin is preferable, and is particularly preferable for disposal.
[0035]
In applications where electret processing is used, filter For the purpose of use, it is preferable to use a fiber having a fiber diameter larger than 15 μm due to the demand for low pressure loss, but even a thinner fiber is not inconvenient depending on the purpose. Moreover, the electret nonwoven fabric which arranged the nonwoven fabric for both is Dust absorption It is intended for curtains, wall hangings, and wallpaper for use, and the polyolefin fiber is arranged at least partially on the surface to which the composite fiber of the present invention is thermally bonded for the purpose of achieving integration by thermal bonding on the assumption of the polyolefin fiber. Using non-woven fabric.
[0036]
Furthermore, in order to achieve higher bulk, that is, higher thickness, lower pressure loss, and simplified thermal bonding with the base fabric, the fibers of the composite fiber nonwoven fabric layer in contact with the base fabric are made into fibers with a fineness of 10 to 200 μm. In addition to thermal bonding for bonding to the base fabric, the physical entanglement effect of thick fibers is also added to reduce the amount of heat received by the base fabric to suppress film formation of the base fabric, and to coagulate, entangle and fuse and bond By increasing the thickness of the lumps, the thickness was increased.
[0037]
When the composite nonwoven fabric obtained by bonding and integrating the above-mentioned thick fiber composite fiber nonwoven fabric layer to the base fabric is electret processed, the basis weight is 90 g / m. 2 It can be processed even under a strong electric field, and it is also possible to laminate the composite fiber nonwoven fabric layer of the present invention. Moreover, the composite nonwoven fabric obtained by bonding and integrating the thick composite fiber nonwoven fabric layer has a lower stiffness than the conventional composite nonwoven fabric, becomes a hard nonwoven fabric, is easy to pleat fold, and has a high shape retention effect.
That is, the composite fibers having different fiber diameters are arranged on a nonwoven fabric (base fabric) layer made of fibers having a fiber diameter of 15 μm or more. In the first stage, the thick composite fiber according to the present invention in which the fiber diameter (d: μm) is 10 <d <200 is arranged on the base fabric. From the thick composite fiber having a fiber diameter of 50 to 10 μm. The resulting layer is ejected with the gap between the melt blow nozzle and the base fabric close to 5 to 15 g / m 2 Most preferably, thick composite fibers having a desired fiber diameter are accumulated. Thus, the thick composite fiber constituting the thick composite fiber layer does not cause any inconvenience even if the fibers have a plurality of types of fiber diameters.
[0038]
The distance between the nozzle and the base fabric is preferably about 5 to 25 cm. This is a closer distance in the normal melt blow spinning process. The reason for close-up and accumulation is to make it easier for the thick composite fibers to penetrate into the base fabric and physically interlace with the thick fibers, and to enhance the fusion bonding effect between the base fabric fibers and the thick fibers. . However, it is natural to set the distance between the nozzle and the base fabric so that the base fabric does not melt with the hot air of melt blow spinning. However, if the operation is continued for a long time, the temperature of the circulating conveyor belt rises, A problem that a part of the resin melts or forms a film is not preferable. In order to prevent this phenomenon, the basis weight is 5 to 15 g / m. 2 The range of using thick fibers having a fiber diameter of 50 to 10 μm is most convenient. The basis weight is 5g / m 2 Is less than 15 g / m. 2 If it exceeds 1, the problem of melting or film formation tends to occur. If the fiber diameter of the thick fiber exceeds 50 μm, partial melting of the fibers constituting the base fabric is likely to occur, and if it is less than 10 μm, the fiber accumulation effect on the surface of the base fabric is large, and the penetration of the thick fibers into the base fabric layer Less is less preferred because the physical entanglement effect of the thick fibers is reduced.
[0039]
Originally, thicker fibers are better for bulkiness, lower pressure loss and higher hardness of the nonwoven fabric (higher nonwoven fabric and higher pleat foldability are better). It is extremely convenient to laminate and integrate the fibers while fusing or fusing them with a low melting point resin that occupies the majority of the fiber surface.
When the composite nonwoven fabric of the present invention is used for a filter application, the filter layer is formed by laminating the finer composite fiber layer of the present invention on the above-described base fabric and thick composite fiber accumulation layer, which is required to collect dust mainly. As a function. The fiber diameter (d: μm) of the finer composite fiber is 0.3 <d <20, and the fiber diameter is arbitrarily selected according to the purpose.
[0040]
The fiber diameter referred to in the present invention means a number average fiber diameter, and the nonwoven fabric of the present invention uses a heat-adhesive conjugate fiber and is arbitrarily partially fused and bonded. Since the dispersion and distribution of the fiber diameter were wide and the fiber diameter was determined by microscopic observation, it was described as a number average. A lump or fiber bundle that was fused and bonded was counted as one.
[0041]
Note that the composite meltblown fiber in the present invention is more advantageous for increasing the bulk by the uneven method, especially when the aggregated and fusion-bonded lump is scattered, and when thick fibers are used, the fiber accumulation is divided into multiple times. It is particularly preferable to do this. Further, even in the fine fiber layer, if air filter applications are assumed, it is particularly preferable to accumulate the fibers in a plurality of times in the same manner as described above in order to avoid unevenness in weight. Further, in these fiber accumulations, the fibers are easily aligned in a certain direction by the melt-blowing method, and therefore, it is preferable to laminate the layers so as to intersect each other as much as possible. In the present invention, this point is taken into consideration in the equipment.
In consideration of the required weight of each layer as described above, the weight of the nonwoven fabric of the present invention depends on the use, but is 30 to 400 g / m. 2 Is preferred, 400 g / m 2 Exceeding 30g / m due to poor hot air penetration. 2 If it is less than 1, it is not convenient because the required weight of each constituent layer cannot be secured. In the case of pleated folding filter, considering its rigidity, 60g / m 2 The above is preferable.
[0042]
The composite nonwoven fabric of this invention can select the fiber to be used and can apply it to various uses. For example, an electret non-woven fabric in which both sides of a polybutene-1 / polypropylene composite fiber as an intermediate layer are occupied by an olefin non-woven fabric to which a hydrophilic substance such as a surfactant is not attached, and is also suitable for a non-woven fabric convenient for a dust collecting curtain, etc. Related.
[0043]
In addition, the melt blown nonwoven fabric body of the present invention has a phenomenon that a hole is quickly opened when it hits a flame, and is excellent in flame retardancy, but a composite nonwoven fabric laminated with a polypropylene spunbond nonwoven fabric is exposed to flame from the melt blown nonwoven fabric side. Although it has good flame retardancy, the spunbond nonwoven fabric side has obtained inferior flame retardancy, and the flame retardant effect agent Flem Stub CGL-116 of Ciba Specialty Chemicals Co., Ltd. is added to the polypropylene resin constituting the spunbond nonwoven fabric. The melt blown composite nonwoven fabric of the present invention added with at least 0.5% by weight to form a spunbond nonwoven fabric is always flame retardant evaluation method JIS. Since it becomes possible to obtain
The above-mentioned flame retardant effect agent CGL-116 is a derivative of a Halus stabilizer, which is a normal weathering stabilizer of polypropylene. Even in combination with the Hals stabilizer and other stabilizers, environmental hormones and harmful substances are removed. Because it does not contain, it is very environmentally friendly.
[0044]
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a cross-sectional shape of a composite fiber that is a constituent fiber of a composite nonwoven fabric according to the present invention. A in FIG. 1 is a cross-sectional shape that is a core component generally called a cat eye, and has a structure in which a high melting point component (1) is elliptical and a low melting point component (2) that is a sheath component surrounds it. . B is a concentric core-sheath structure in which the core is a high melting point component and the sheath is a low melting point component. C has a three-layer structure in which a high melting point component is sandwiched between low melting point components.
[0045]
FIG. 2 is an enlarged view of a side cross section of the composite fiber nonwoven fabric of the present invention. Around the fiber mass (3) where the composite fiber is partially heat-bonded, the composite fiber is thick, the composite fiber (4) and the thin composite fiber (5) are both non-woven fabrics with wide fiber gaps, low fiber density and high bulk The convex part is formed. On the other hand, the middle part of the fiber lump and the fiber lump is a part (6) having a high fiber density.
[0046]
Next, the effect examples and comparative examples of the present invention will be described in detail. In addition, although it demonstrates mainly with the melt blown nonwoven fabric of the composite fiber which uses the sheath component which is 1 form of this invention as polybutene-1 and makes a core component into polypropylene, the composite fiber nonwoven fabric and composite nonwoven fabric of another form are also implemented. It goes without saying that it can be easily made with reference to an example.
[0047]
【Example】
The composite fiber fiberized by the melt-blowing method of the present invention is a composite of 850 holes with a width of less than 70 cm that can form a composite fiber by extruding individual thermoplastic resins from two extruders and quantitatively supplying them with a gear pump. Using a nozzle, it is discharged into a high-speed heated air stream from a row of orifices, and at the same time, it is elongated into the air stream to form a basically continuous fiber, which is accumulated on a net conveyor equipped with suction equipment. A polypropylene spunbond nonwoven fabric preheat-treated at 140 ° C. is positioned on the conveyor, and a thick composite fiber having an average fineness of 6 to 10 dTex (23 to 38 μmφ) is 15 g / m on the nonwoven fabric. 2 The composite fiber nonwoven fabric of the present invention was manufactured by stacking a plurality of thick fibers or fine fibers each having a desired basis weight, and by laminating a plurality of layers of thick fibers or fine fibers each having a desired basis weight. Each layer was accumulated by intersecting at an angle of at least 30 degrees.
Resins used in the present invention are as shown in Table 1, PP is polypropylene, PB is polybutene-1 (Mitsui Chemicals Tafmer, density D: 0.92 g / cm Three ), PE is polyethylene, PT is polyethylene terephthalate (using a conventional resin with a limiting viscosity IV value of 0.64), PM is polymethylpentene (Mitsui Chemicals TPX), EP is an ethylene / propylene copolymer with excess propylene It was used. The composite ratio of the sheath to the core component is 1: 1, and the melt flowability MFR is measured at temperatures of PT and PM of 290 ° C. and others at 230 ° C., and the unit is g / 10 minutes. The Q value is a ratio of weight average molecular weight / number average molecular weight.
[0048]
[Table 1]
(Examples 1-7, Comparative Examples 1-2) The composite fiber meltblown nonwoven fabric of the present invention was made into a nonwoven fabric under the conditions shown in Table 2 using the resins shown in Table 1 and the steps described above. The spinning temperature refers to the nozzle temperature, which is ejected using high-pressure hot air at the same temperature, sucked with a suction amount of 5 times or more of the amount of hot air blown, and a spunbonded nonwoven fabric of about 7 dTex at a weight of 15 g. The composite nonwoven fabric of an Example and a comparative example was obtained by accumulating on.
The fiber diameter in Table 2 is the number average fiber diameter μm, and the fused fiber is excluded, and each fiber layer has at least two times of accumulation, and its total weight is g / m. 2 The thickness was measured by the JIS-L-1913-6.1.2A method.
In Comparative Example 1, the nozzle of the example is a nozzle with a pitch of 3 mm, and the nonwoven fabric has a small amount of fiber mass that is agglomerated, entangled and thermally bonded.
Table 2 shows the resin components used in each example and comparative example, the bulkiness of the composite fiber nonwoven fabric, and the like.
[0050]
(Example 8) In Example 1, the polypropylene spunbonded nonwoven fabric was not used, and the composite fiber meltblown nonwoven fabric of the present invention was laminated. (Appearance) The thickness was the same as in Example 1.
(Example 9) Nonwoven fabric of Example 2 and 2dTex, basis weight 40 g / m 2 The polypropylene spunbonded nonwoven fabric was pasted together while being pressed with a hot air processing machine at 140 ° C. using a bar, and then subjected to electret thermal processing in the same manner as in Example 1 to obtain an electret nonwoven fabric. When it was put in a box in which atmospheric dust was diffused, atmospheric dust was adsorbed remarkably, and the spunbond nonwoven fabric on the surface became grayish.
(Example 10) The basis weight is 60 g / m. 2 The 6dTex rayon spunlace nonwoven fabric was fired under anaerobic conditions at 650 to 700 ° C., and the activated carbon fiber nonwoven fabric was placed on the 7dTex spunbond nonwoven fabric used in Example 1, and then a 2dTex rayon Fiber basis weight 30g / m 2 A spunlace nonwoven fabric obtained by spunlace processing and entangled and integrated with the rayon fiber, and replacing the nonwoven fabric with the spunbond nonwoven fabric in Example 1, with the spunbond nonwoven fabric layer on top, A melt blown nonwoven fabric was laminated in the same manner as in Example 1 to obtain a composite nonwoven fabric. The composite nonwoven fabric retained at least the ability to collect hydrogen sulfide.
[0051]
[Table 2]
When the nonwoven fabric obtained in Examples 1 to 7 was pleated and folded using a folding machine, the degree of gear roll engagement was good and the pleats could be folded smoothly. The smooth nonwoven fabrics of Comparative Examples 1 and 2 were difficult to hang and the workability was poor.
Among the nonwoven fabrics obtained in Examples and Comparative Examples, the composite fiber nonwoven fabric using PB as the sheath component is a DC high voltage application device in which needles are embedded at regular intervals inside and outside the hot air processing machine at 120 ° C. Under quenching, 9 Kv negative direct current was applied to the electret nonwoven fabric to remove static electricity. Using these, the collection efficiency of 0.5 μm particles of atmospheric dust and the pressure loss at that time were measured. Table 2 shows the results.
In addition, the measurement flow rate of collection efficiency was 5.3 cm / s based on JIS-B-9908, and the nonwoven fabric of each Example was mounted instead of the filter unit, and the filtration surface was measured as 100 mmφ.
The bulky effect of each example appears in the low pressure loss.
[0053]
(Example 11) 0.1% by weight of Ciba's weathering stabilizer 944, 1.5% by weight of flame retardant CGL116, and phosphorous stabilizer 168 for the polypropylene resin constituting the polypropylene spunbonded nonwoven fabric of Example 1 The composite nonwoven fabric added with 0.3% by weight always showed good flame retardancy.
[0054]
【The invention's effect】
One of the aspects of the present invention is that a composite fiber using a thermoplastic resin that has been conventionally used in staple fibers is directly made into a non-woven fabric by using a melt-blown fiber technique. Conventional fibers such as staple fibers and multifilament fibers are used. In the fiberization method, a thermoplastic resin that is easily fused, which has been a very difficult problem, can be used positively. Particularly preferred is a composite that uses the above-described easily fused resin on the fiber surface. Although it is a fiber, this fusion phenomenon is actively used to cause partial fusion of the fiber during the ejection of the fiber, to disperse the clumps that have been agglomerated, entangled, and fused and bonded, and unevenness is formed on the nonwoven fabric surface. By making it appear and increasing the apparent thickness, a nonwoven fabric with a thickness that could not be achieved with a conventional single-fiber meltblown nonwoven fabric was obtained. Due to this increase in bulk, an air filter material that has conventionally been made mainly of an air filter having a structure in which a melt blown non-woven fabric is bonded to a polyester resin-bonded non-woven fabric can be used without problems even in a pleated folder. Moreover, in the case of a composite nonwoven fabric, the resin impregnation treatment improves the adhesion between the nonwoven fabrics, and the problem of easy peeling is solved.
[0055]
In addition, in disposal such as incineration, air filter materials made of all polyolefin resin, which does not use any polyester material that can be smoked, can be provided. However, the polyolefin resin has high electrical insulation, and even if a melt blown nonwoven fabric is simply laminated as in the past, a new problem has arisen that sufficient electret processing cannot be performed due to its electrical insulation. The melt blown nonwoven fabric of the present invention was able to achieve a remarkable electret property even if the basis weight was insufficient with the melt blown nonwoven fabric.
The air filter material made of the all polyolefin resin of the present invention is particularly easy to dispose of, and does not contain any environmental hormones or other harmful substances as a material. Because it does not generate harmful gases such as, it is suitable as a non-woven material considering humans and the environment.
[Brief description of the drawings]
1A, B, and C in FIG. 1 are examples of a cross-sectional view of a composite fiber constituting a composite nonwoven fabric of the present invention.
FIG. 2 is an enlarged view of a side sectional view of the composite nonwoven fabric of the present invention.
[Explanation of symbols]
1 High melting point components
2 Low melting point components
3 Fiber mass
4 Thick composite fiber
5 Thin composite fibers
6 Parts with high fiber density
Claims (12)
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Cited By (2)
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| WO2013024770A1 (en) | 2011-08-12 | 2013-02-21 | Jnc株式会社 | Blended filament nonwoven fabric |
| WO2014106695A1 (en) | 2013-01-03 | 2014-07-10 | Philippe Caruso | Synthetic-panel manufacturing device having a wide pouring cup |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4800598B2 (en) * | 2004-07-30 | 2011-10-26 | ダイワボウホールディングス株式会社 | Manufacturing method of electret filter material made of pleated folded nonwoven fabric and filter material using the same |
| JP5080041B2 (en) * | 2006-08-30 | 2012-11-21 | 日本バイリーン株式会社 | Air filter medium, streamer filter using the same, and method for producing air filter medium |
| US20100267305A1 (en) * | 2007-12-24 | 2010-10-21 | Basell Poliolefine Italia S.R.L. | Polyolefin fibres |
| KR101354301B1 (en) * | 2012-04-06 | 2014-01-24 | 웅진케미칼 주식회사 | Filter assembly for fan type cooling apparatus |
| KR101379069B1 (en) * | 2012-04-06 | 2014-04-02 | 웅진케미칼 주식회사 | Manufacturing method of filter assembly for fan type cooling apparatus |
| JPWO2021010178A1 (en) * | 2019-07-16 | 2021-01-21 |
-
2002
- 2002-07-03 JP JP2002194131A patent/JP4142903B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013024770A1 (en) | 2011-08-12 | 2013-02-21 | Jnc株式会社 | Blended filament nonwoven fabric |
| KR20140049031A (en) | 2011-08-12 | 2014-04-24 | 제이엔씨 주식회사 | Blended filament nonwoven fabric |
| US9662601B2 (en) | 2011-08-12 | 2017-05-30 | Jnc Corporation | Blended filament nonwoven fabric |
| WO2014106695A1 (en) | 2013-01-03 | 2014-07-10 | Philippe Caruso | Synthetic-panel manufacturing device having a wide pouring cup |
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| Publication number | Publication date |
|---|---|
| JP2004003065A (en) | 2004-01-08 |
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