JP3588635B2 - Thermally bonded conjugate fiber and spherical body of high elastic fiber comprising the same - Google Patents

Description

表１の評価は、複合繊維（ｂ）を基準として、相対評価したものである。ただし該表中‘＊）’は、ポリエステル系エラストマーの場合を示し、‘＊＊）’は、仮に膠着がないと推定した場合を示す。
該表からすれば、複合繊維（ｃ）は、複合繊維の５つの要求特性（表中の４）〜８）に対応）のうち４要件において優れており、一見、理想的な繊維のようにみえる。しかし、この繊維の膠着防止能が「小」すなわち、悪いということは、以下に述べるように、工業的製造工程や得られた製品の品質に致命的な不利益をもたらす。
即ち、複合繊維は先ず、未延伸原糸としてワインダーや原トウ缶の中に捕集するが、十分冷却されず、単繊維同士を集束した時点でエラストマーによる膠着が生じるが、ワインダー上に巻取って保管している状態でも繊維同士の膠着が進行し、硬い紐状になってしまったり、サブトウ同士が強固に固着し、ワインダーから解舒できなくなるという問題がある。
また、原トウ缶の中に捕集する場合でも、紐状に硬く膠着してしまうため収缶量が著しく低下し、大幅に生産性が低下するという問題がある。このように紐状に膠着したサブトウは延伸工程で、極めて延伸性が悪く、糸切れや延伸ローラー巻付が多発し、安定な生産はできない。仮に熱接着性繊維が製造できても、その繊維同士が集団となって膠着しているため、不織布などの繊維構造体として他のマトリックス繊維と混合して使用する場合に、熱処理時の繊維同士を接着させるのに有効な固着点の形成個数が少ないので、接着性が著しく低く、弾力性がなく、外力によって繊維構造体が容易に破壊されてしまい、耐久性のないものとなってしまうという問題点がある。
他方、複合繊維（ａ）にあっては、膠着防止能は複合繊維（ｂ）または（ｃ）に比して、倍増するものの本来の目的である熱接着機能、捲縮弾性が著しく劣るという問題を抱えている。
発明の開示
本発明の目的は、結晶性の熱可塑性エラストマーを一成分として配した熱接着性複合繊維の製造時に不可避的に生じ、繊維の取り扱い性、工程特性さらに本来の熱接着性能までも阻害する膠着現象の解消と、ポリマー間の界面接着強度、本来の接着性能並びに捲縮弾性の共存という、これまで未解決のまま放置されていた課題を解決しようとするものである。
更に本発明の他の目的は、吹き込み特性に優れ、嵩高性に優れしかも、風合いもソフトで、弾力性も高く、圧縮回復耐久性に優れたクッション材や高弾性繊維球状体（fiber ball）を与える熱接着性複合繊維提供することにある。
本発明者等の研究によれば、上記目的は熱接着性複合繊維の断面において、エラストマー成分を三日月状に配し、しかもそのときの幾何学的ディメンジョンを下記に示すように特定するとき、所望の複合繊維が得られることが判明した。
即ち、本発明においては、結晶性の熱可塑性エラストマー（Ｅ）と、該エラストマー（Ｅ）よりも融点の高い結晶性の非弾性ポリエステル（Ｐ）とが、円形の繊維断面においてE:P＝20:80〜80:20の面積比率で配されてなる複合繊維において、
該繊維はその断面及び表面が以下の要件▲１▼〜▲５▼により特定される。
要件
▲１▼ 該エラストマー（Ｅ）は、繊維断面において、曲率半径の異なる２本の円弧により形成される三日月形状に配され、且つ曲率半径の大なる曲線（r₁）が外周線の一部を形成していること；
▲２▼ 該ポリエステル（Ｐ）は、繊維断面において、三日月形状を形成する２本の曲線のうち、曲率半径の小さい方の曲線（r₂）に沿って、該エラストマーと接合し、他方、曲率半径の大きい方の曲線（r₁）は、その周率Ｒが25〜49％の範囲で外周線となるように円弧状に繊維表面の一部を形成していること；
（但し、周率Ｒは以下の定義に従う。第１図の（r₁）を半径とする円において、その全円周（L₁＋L₃）に占める（L₃）の割合によって示され、該周率Ｒは〔Ｒ＝｛（L₃）／（L₁＋L₃）｝×100（％）〕により算出される。）
▲３▼ 該曲率半径（r₁）と曲率半径（r₂）との比（r₁/r₂）である曲率半径比Crが１を越えて２以下の範囲にあること；
▲４▼ 該曲率半径（r₂）の曲線の湾曲比Ｃが1.1〜2.5の範囲にあること；及び、
（但し、湾曲比Ｃは以下の定義に従う。第１図において、（r₂）を半径とする円弧（L₂）の長さと、（r₁）を半径とする円の円周と該円弧（L₂）との接点間（P₁−P₂間）の長さ（Ｌ）と、の比によって示され、該湾曲比Ｃは｛Ｃ＝（L₂）／（Ｌ）｝により算出される。）
▲５▼ 該エラストマー（Ｅ）とポリエステル（Ｐ）との肉厚比が1.2〜３の範囲にあること；
（但し、肉厚比Ｄは以下の定義に従う。第１図において（r₁）を半径とする円の中心と（r₂）を半径とする円弧を一部とする円の中心と、を通る直線方向におけるポリエステル（Ｐ）成分の長さ（L_P）とエラストマー（Ｅ）成分の長さ（L_E）との比によって示され、該肉厚比Ｄは｛Ｄ＝（L_P）／（L_E）｝により算出される。）
【図面の簡単な説明】
第１図は、本発明の熱接着性複合繊維の繊維横断面を示した模式図であり、
第２図（ａ）、（ｂ）および（ｃ）は、それぞれ、従来の熱接着性複合繊維の繊維横断面を示した模式図である。
第３図は、本発明の熱接着性複合繊維を製造するための複合紡糸口金の縦断面を示した模式図である。
発明を実施するための最良の形態
上記の、本発明の目的達成のために要求される▲１▼〜▲５▼の要件について、図面に基づいて詳細に説明する。
第１図には、本発明の課題を解決した熱接着性複合繊維の断面の一例（ここでは真円）が示されている。
第１図において、Ｅは結晶性の熱可塑性エラストマー、Ｐは結晶性の非弾性ポリエステルを示す。ここで特徴的なことは、その断面が曲率半径（r₁）の円において、Ｅ成分は（r₁）、（r₂）という曲率半径の異なる二つの円弧で形成される三日月形状に配され、その外周線（L₁）は曲率半径（r₁）の円弧であって、そのまま繊維断面の一部を構成し、他方、Ｐ成分は繊維断面において、三日月形状を形成する２本の曲線のうち、曲率半径の小さいほうの曲線（r₂）に沿って、該エラストマーと接合している。そして、Ｐ成分もまた外周線（L₃）で示されるように繊維表面の一部を形成するが、そのときの（L₃）の繊維断面周率Ｒ〔Ｒ＝（L₃）／｛（L₁）＋（L₃）｝×100（％）〕が25〜49％、好ましくは28〜40％の範囲にあることが必要である。このＲが25％より低くなると、複合繊維を製造する際に繊維同士が融着や圧着されやすく、膠着が生じて製造のトラブルとなりやすい。さらにＥ成分が柔らかいため、繊維の開繊や混綿などに使われる回転ガーネットワイヤーに食い込んだり、ひっかいたりして通過性が悪く長時間の製造が困難になったり均一な混綿嵩高綿が得られにくくなる。また、接着部分（L₁）が多くなるため周りの繊維との熱固着点が多くなり、細かいネットワーク構造となり弾力性が出にくくなる。一方、このＲが49％を越えると、繊維表面の熱融着成分が覆っている面積が接着機能という面から少なくなって、所望の接着が起きにくくなる。
このような断面において、曲率半径（r₁）と（r₂）との比｛（r₁）／（r₂）｝である曲率半径比Crは１より大であることが必要である。
該Cr値が１以下ではＥ成分とＰ成分の接合線である両者の界面が剥離しやすく、一旦剥離すると繊維間接着力が大巾に低下したり、立体捲縮発現能が低下し、捲縮の発現が小さくなってしまい好ましくない。また、複合繊維の捲縮弾性率が低下し、開綿工程の開繊不良、カードシリンダー捲付多発、カードウエブ斑発生、ネップ発生等のトラブルを生じ好ましくない。
一方、該Cr値が２を越えるとＥ成分の繊維断面に対する占有面積が大きくなりすぎて好ましくない。
次に、上記の複合形態において、Ｅ成分とＰ成分の接合線に関する湾曲度Ｃ、つまり第１図において、周長（L₂）に対する、点（P₁）と点（P₂）とを結ぶ線分（Ｌ）の比｛Ｃ＝（L₂）／（Ｌ）｝が1.1〜2.5、好ましくは1.2〜2.0の範囲にあることが必要である。
このＣの値が1.1より低くなると、例えば従来の、第２図（ａ）の様な複合形態ではポリマー同士が剥離し易くなって、捲縮の発現が小さくなったり、また熱処理での捲縮発現が少なくなり、非弾性捲縮短繊維を巻き込んだ可撓性熱固着点が形成しにくくなる。一方、このＣの値が2.5を越えると、捲縮が大きくなり過ぎたり、熱処理での捲縮も極端に起きやすく繊維構造体の嵩などが小さくなったり、風合いに“ゴロゴロ”感がでて好ましくない。ここに、“ゴロゴロ”感とは、繊維構造体の表面を触ったとき、その構造体中に、小さく硬い異物が存在しているかのような、不快な触感をいう。
最後に、Ｅ成分とＰ成分との肉厚比（Ｄ）を特定することも極めて重要である。このＤは第１図のＥ成分の最大肉厚長を（L_E）、Ｐ成分の最大肉厚長を（L_P）とするとき、｛Ｄ＝（L_P）／（L_E）｝で表され、この値が1.2〜3.0、好ましくは1.5〜2.9の範囲にあることが必要である。このＤが1.2より低くなると、捲縮の発現が小さくなったり、熱処理での捲縮発現が少なくなり同様に繊維構造体化しにくい、非弾性捲縮短繊維を巻き込みながらの融着が起きにくく好ましくない。また、このＤが3.0を越えると、捲縮が大きくなり過ぎたり、熱処理での捲縮も極端に起きやすく嵩などが小さくなったり、風合いにゴロゴロ感が出て好ましくない。
本発明においてＰ成分の融点はＥ成分の融点よりも10〜190℃高いことが好ましい。これにより該複合繊維の熱接着時にＥ成分のみを、Ｅ成分の融点以上Ｐ成分の融点未満の温度で熱処理をおこなって熱溶融することにより、Ｐ成分は元の繊維形態を維持し、繊維同士の固着点を保持し、接着強力を高いレベルに維持し、弾力性、耐久性を向上させることができる。
ここで、Ｐ成分とは、ポリエステルであれば特に限定されないが、通常のポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリヘキサメチレンテレフタレート、ポリテトラメチレンテレフタレート、ポリ−1,4−ジメチルシクロヘキサンテレフタレート、ポリピバロラクトンまたはこれらの共重合体エステルからなるポリマーであるが、繰り返し歪みがかかる用途であるため歪みの残しにくいポリブチレンテレフタレートが好ましい。特に、複合繊維の融着成分にもちいられるエラストマーのハードセグメントがポリブチレン系の場合は特に剥離などの問題がなく良好である。このＰ成分の融点は110〜290℃の範囲にあることが好ましい。
これに対して、Ｅ成分の融点は100〜220℃にあるのが適当である。100℃未満では、本発明の前掲▲１▼から▲５▼の要件を満足するように紡糸しても紡糸時の繊維同士の膠着を完全に防ぎきれないことがある。また該複合繊維を、例えば夏場の音調装置のない倉庫内に、梱包ベールを多段に積載した場合に、繊維間の膠着を生じる懸念がある。220℃を越えると、熱処理機の安定処理温度の上限能力いっぱいであり、部分的に接着強力の斑を生じ、硬さ斑の原因となり、好ましくない、該成分（Ｅ）の融点は130〜180℃が膠着防止、熱処理に安定性等の点から、より望ましい範囲である。
このＥ成分としては、紡糸適正や物性等の面からポリウレタン系エラストマーや結晶性ポリエステル系エラストマーが好ましい。
ポリウレタン系エラストマーとしては、分子量が500〜6000程度の低融点ポリオール、例えばジヒドロキシポリエーテル、ジヒドロキシポリエステル、ジヒドロキシポリカーボネイト、ジヒドロキシポリエステルアミド等と、分子量500以下の有機ジイソシアネート、例えば、P,P−ジフェニルメタンジイソシアネート、トリシンジイソシアネート、イソホロンジイソシアネート、水素化ジフェニルメタンジイソシアネート、キシリレンジイソシアネート、2,6−ジイソシアネートメチルカプロエート、ヘキサメチレンジイソシアネート等と、分子量500以下の鎖伸長剤、例えばグリコール、アミノアルコールあるいはトリオールとの反応で得られるポリマーを挙げることができる。これらのポリマーのうち、特に好ましいものはポリオールとしてポリテトラメチレングリコール、またはポリ−ε−カプロラクトンである。有機ジイソシアネートとしてはp,p′−ジフェニルメタンジイソシアネートが好適である。また、鎖伸長剤としては、p,p′−ビスヒドロキシエトキシベンゼン及び1,4−ブタンジオールが好適である。
一方、結晶性ポリエステル系エラストマーとしては、熱可塑性ポリエステルをハードセグメントとし、ポリ（アルキレンオキシド）グリコールをソフトセグメントとして共重合してなる、ポリエーテルエステルブロック共重合体、より具体的にはテレフタル酸、イソフタル酸、フタル酸、ナフタレン−2,6−ジカルボン酸、ナフタレン−2,7−ジカルボン酸、ジフェニル−4,4′−ジカルボン酸、ジフェノキシエタンジカルボン酸、３−スルフォイソフタル酸ナトリウム等の芳香族ジカルボン酸、1,4−ジクロヘキサンジカルボン酸等の脂環式ジカルボン酸、コハク酸、シュウ酸、アジピン酸、セバシン酸、ドデカンジ酸、ダイマー酸等の脂肪族ジカルボン酸、またはこれらのエステル形成誘導体等から選ばれたジカルボン酸の少なくとも一種と、1,4−ブタンジオール、ジエチレングリコール、トリメチレングリコール、テトラメチレングリコール、ペンタメチレングリコール、ヘキサメチレングリコール、ネオペンチルグリコール、デカメチレングリコール等の脂肪族ジオール、あるいは1,1−シクロヘキサンジメタノール、1,4−シクロヘキサンジメタノール、トリシクロデカンジメタノール等の脂環式ジオール、またはこれらのエステル形成誘導体などから選ばれたジオール成分の少なくとも一種、および平均分子量が300〜5000程度の、ポリエチレングリコール、ポリ（1,2−プロピレンオキシド）グリコール、ポリ（1,3−プロピレンオキシド）グリコール、ポリ（テトラメチレンオキシド）グリコール、エチレンオキシドとプロピレンオキシドとの共重合体、エチレンオキシドとテトラヒドロフランとの共重合体等のポリ（アルキレンオキシド）グリコールのうち少なくとも一種から構成される三元共重合体であることが好ましい。
しかしながら、ポリエステル系複合成分との接着性や耐熱特性、強度など物性の面などから、ポリブチレン系テレフタレートをハードセグメントとし、ポリオキシテトラメチレングリコールをソフトセグメントとするポリエーテルエステルブロック共重合体が特に好ましい。この場合、ハードセグメントを構成するポリエステル部分は、該共重合体の全酸成分を基準として共重合割合（全酸成分を基準としてモル％を示す）がテレフタル酸を40〜100モル％、イソフタル酸を０〜50モル％含むものが用いられる。テレフタル酸、イソフタル酸以外の酸成分としてはフタル酸、アジピン酸、セバシン酸、アゼライン酸、ドデカン二酸、2,6−ナフタレンジカルボン酸、５−ナトリウムスルホイソフタル酸、1,4−シクロヘキサンジカルボン酸等が所定の融点を得るためと、弾力性、耐久性、等のの品質を向上させるからも好ましく用いられる。特にテレフタル酸を50〜90モル％とイソフタル酸を10〜35モル％含むものがより好ましく用いられる。
また、該ポリエステル部分のグリコール成分は主たる成分が、1,4−ブタンジオールであることがよい。尚、ここでいう「主たる」とは、全グリコール成分の80モル％以上が1,4−ブタンジオールであって、20モル％以下の範囲内では他種グリコール成分が共重合されていてもよいことをいう。好ましく用いられる共重合グリコール成分としては、エチレングリコール、トリメチレングリコール、1,5−ペンタンジオール、1,6−ヘキサンジオール、ジエチレングリコール、1,4−シクロヘキサンジオール、1,4−シクロヘキサンジメタノール等をあげることができる。
さらに上記ポリエーテルエステルブロック共重合体は、平均分子量が300〜5000のポリ（アルキレンオキシド）グリコール成分を５〜80重量％含むものである平均分子量800〜4000で、グリコール成分を30〜70重量％含むことが特に好ましい。平均分子量が300未満の場合には、得られるブロック共重合体のブロック性が低下して弾性回復性能が不充分となるし、一方5000を越える場合には、ポリ（アルキレンオキシド）グリコール成分の共重合性が低下して弾性回復性能が不充分となるため好ましくない。
該グリコール成分の共重合量が５重量％未満の場合には、該複合繊維を加熱接着処理してクッション材等の成形しても本発明の目的とする弾性特性の良好なものは得られず、一方、該グリコール成分の80重量％を越える場合には、得られるブロック共重合体の力学的特性及び耐熱性、耐光性の耐久性が低下するため好ましくない。
好ましく用いられるポリ（アルキレンオキシド）グリコールとしては、ポリエチレングリコール、ポリ（プロピレンオキシド）グリコール、ポリ（テトラメチレンオキシド）グリコールの単独重合体が好ましい。さらには、前記単独重合体を構成する反復担体の２種以上がランダム又はブロック状に共重合したランダム共重合体又はブロック共重合体を使用してもよく、また前記単独重合体又は共重合体の２種以上が混合された混合重合体を使用してもよい。このようなポリエーテルエステルブロック共重合体は周知の共重合ポリエステルの製造方法をもちいて得ることができる。
本発明の複合繊維を製造するに際して、Ｅ成分とＰ成分とは、夫々、通常水分率0.1％以下になるまで乾燥した後、紡糸に供する。
結晶性熱可塑性エラストマーと非弾性ポリエステルとを複合し、繊維を製造する方法は周知の紡糸装置と方法により行うことができる。
図面をもって説明するならば、例えば第３図に示すような複合口金を使用して本発明の複合繊維が得られる。尚、第３図の複合口金について、上板１に設けられたピン３からＰ成分を溶融状態で流し、上板１と下板間にＥ成分を溶融状態で流して下板２に設けたノズル４より複合させて吐出する。紡糸に際して、ポリマー吐出後冷却固化された複合繊維糸条は紡糸油剤を付与して引き取るか、あるいは、引き続いて、２〜５倍に延伸して、引き取ることができる。
ここで、この第３図に示す紡糸口金を用いることにより、第１図に示す繊維断面を有する該複合繊維が形成される理由は、Ｐ成分とＥ成分との融点の違いにより説明することが出来る。
即ち、両者の融点の違いは溶融粘度に直接関係してくることから、同じ温度下では、Ｐ成分の方が粘度が高く（即ち、硬く）、Ｅ成分の方が溶融粘度が低い（即ち、柔らかい）。
つまり、ピン３から流された溶融状態のＰ成分は、溶融状態のＥ成分の吐出圧によりほとんど影響を受けることなく、そのまま鉛直方向に流れていき、周りのＥ成分を押しのけつつ下板２と接触する。更に、下板２に沿いながら最終的にノズル４から吐出されることで、第１図に示されるような繊維断面が形成される。
紡糸された直後の集束前または集束中の糸条に対して単繊維同士の間に、紡糸油剤としての非晶性ポリエステル・ポリエーテル系ブロック共重合体を介在させることは、膠着防止策として著しい効果がある。
同時に、複合繊維の延伸性を向上させ、カードを通過させて繊維構造体を形成する際にもともと繊維が柔らかく、カード性が著しく劣るが、非晶性ポリエーテルエステル系ブロック共重合体を繊維重量を基準として0.02〜５重量％の範囲で付与することにより、繊維の平滑性を高め、且つ、熱接着時の溶融ポリマーの濡れ性も向上させるため接着強力が増加し、繊維構造体の弾力性、耐久性が大巾に向上する。
この、非晶性ポリエーテルエステルブロック共重合体の繊維重量を基準とした付与量が0.02重量％未満では膠着防止、カード性向上、接着力向上の効果を得るためには不充分である。一方、該付着量が５重量％を越えるとそれ以上多くこの非晶性ポリエステルポリエーテルブロック共重合体の付着量を増やしても、膠着防止、カード性向上、熱接着力向上等の効果は得られず、かえって、繊維表面の粘着性が増加し、カード機での粘着捲付が発生し、均一な繊維構造体が得られず、硬さ斑等が発生し、好ましくない。
この非晶性ポリエーテルエステル系ブロック共重合体は、テレフタル酸及び／またはイソフタール酸及び／またはメタソジウムスルフォイソフタール酸またはそれらの低級アルキルエステル、低級アルキレングリコール並びにポリアルキレングリコール及び／またはポリアルキレングリコールモノエーテルからなるポリエーテルエステルブロック共重合体である。
例えばテレフタール酸−アルキレングリコール−ポリアルキレングリコール、テレフタール酸−イソフタール酸−アルキレングリコール−ポリアルキレングリコール、テレフタール酸−アルキレングリコール−ポリアルキレングリコールモノエーテル、テレフタール酸−イソフタール酸−ポリアルキレングリコール−ポリアルキレングリコールモノエーテル、テレフタール酸−メタソジウムスルフォイソフタール酸−アルキレングリコール−ポリアルキレングリコール、テレフタール酸−イソフタール酸−メタソジウムスルフォイソフタール酸−アルキレングリコール−ポリアルキレングリコール等を挙げることができ、テレフタレート単位とイソフタレート単位または／及びメタソジウムスルフォイソフタレート単位との比は100:0〜50:50（モル比）が紡糸集束時の密着を防止するために好ましい。さらに該ブロック共重合体を付与した複合繊維の膠着防止能を高めるためには、テレフタレート単位とイソフタレート単位または／及びメタソジウムスルホイソフタレート単位との比は90:10〜50:50（モル比）が特に好ましい。
また、該ブロック共重合体において通常はテレフタレート単位及びイソフタレート単位または／及びメタソジウムスルホイソフタレート単位とポリアルキレングリコール単位との比は2:1〜151（モル比）であり、紡糸集束時の単繊維同士の密着発生防止、繊維の接着強力の向上等を考慮すると3:1〜8:1（モル比）が特に好ましい。
ここで、該非晶性ブロック共重合体の製造に用いるアルキレングリコールはエチレングリコール、プロピレングリコール、テトラメチレングリコール、デカメチレングリコール等の炭素数が２〜10のアルキレングリコールなどであり、ポリアルキレングリコールは通常平均分子量が600〜12,000、好ましくは平均分子量、1,000〜5,000ポリエチレングリコール、ポリエチレングリコール・ポリプロピレングリコール共重合体、ポリエチレングリコール・ポリテトラメチレングリコール共重合体、ポリプロピレングリコール等の他、ポリエチレングリコール、ポリプロピレングリコール等のモノメチルエーテル、モノエチルエーテル、モノフェニルエーテル等が好ましい。しかし、単繊維同士の膠着防止性向上の点から特に好ましいのはポリエチレングリコールのモノエーテル類である。
また、該非晶性ブロック共重合体の平均分子量は使用するポリアルキレングリコールの分子量にもよるが、通常2,000〜20,000、好ましくは3,000〜13,000である。平均分子量が2,000未満では延伸性向上、密着防止、熱接着力向上の点で不充分であり、また20,000を越えると延伸性、熱接着力が低下し好ましくない。該ブロック共重合体の重縮合時に分子量を調節するために使用するポリアルキレングリコールはモノメチルエーテル、モノエチルエーテル、モノフェニルエーテルのような片方の末端基が封鎖されたものが好ましい。
また該非晶性ブロック共重合体はポリオキシエチレンアルキルフェニルエーテルホスフェートのアルカリ金属塩、ポリオキシエチレンアルキルフェニルエーテルサルフェートのアルカリ金属及び／またはこれらのアンモニウム塩、アルカノールアミン塩等の界面活性剤を用いて分散させる。非晶性ブロック共重合体分散液の凝集開始温度は30〜100℃であることが好ましく、更に好ましくは60〜90℃である。なお該非晶性ブロック共重合体の使用量は、複合繊維重量を基準として0.02〜5.0重量％であることが好ましく、特に好ましくは0.1〜3.0重量％である。
本発明の熱接着性複合繊維は、繊度が0.5〜200デニールの範囲が好ましい。0.5デニール未満では繊維構造体として熱接着処理した場合接着強力が不足し、十分な弾力性、耐久性が得られず、200デニールを越えると、繊維等の糸条冷却が不十分となり、本発明の如く、断面形状を特定しても単繊維同士の膠着を防ぐことが困難となる。
その結果、繊維の接着性能が低下し、弾力性や耐久性が小さくなってしまう。特に２〜100デニールの範囲が好ましい。本発明の複合繊維には延伸後に押し込みクリンパーで機械捲縮の捲縮を付与する場合があるが、その捲縮数は、５〜25個／インチ、捲縮度は、５〜30％の範囲が好ましい。捲縮数が５個／インチ未満、捲縮度が５％未満ではカード時にカードウエブが切れたり、得られた繊維構造体の嵩が著しく低下するので好ましくない。捲縮数が25個／インチを、捲縮度が30％を越えるとカード機の通過性が悪くなり、ウエブ斑、ネップが多発し、好ましくない。特に捲縮数が８〜20個／インチ、捲縮度が６〜18％の範囲が特に好ましい。また、その時の短繊維のカット長は、10〜100mmの範囲内にあることが好ましく、特に15〜95mmの範囲内にあることが好ましい。
以上に述べた熱接着性複合繊維は、長繊維、短繊維の形状を問わずそれ自体を単独で用いても不織布・シート等に熱成型することができるが、最も好ましいのは、非弾性ポリエステル系捲縮短繊維をマトリックスとする繊維集合体中にこの複合繊維を捲縮短繊維の形で分散・混入させ、所望の形状に熱成型することである。この態様は冒頭に掲げたWO91/19032公報に典型的に開示されている。
マトリックスとなる非弾性ポリエステル形捲縮短繊維とは、捲縮形態が螺旋状やオメガ型あるいは一部にそれら形状を持つ非弾性ポリエステル系捲縮短繊維であれば何でもよい。また非弾性ポリエステル系捲縮短繊維とは、通常のポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリヘキサメチレンテレフタレート、ポリテトラメチレンテレフタレート、ポリ−1,4−ジメチルシクロヘキサンテレフタレート、ポリピバロラクトンまたはこれらの共重合体エステルからなる捲縮短繊維ないしそれら捲縮短繊維の混綿体、または上記のポリマーのうち２種以上のポリマーの重合度や共重合成分を変えたサイドバイサイド型の繊維断面が左右非対象に構成された、螺旋形状の捲縮を発現した複合短繊などである。勿論、捲縮を発現するためには、紡糸のさいに繊維の片面を強く冷却する異方冷却により延伸、弛緩熱処理の際に螺旋状やオメガ型捲縮を発現したものも好ましい。これらの短繊維の断面形状は円形、扁平、異型または中空のいずれであってもよい。
この捲縮短繊維が繊維構造体の骨格になるために、該ポリエステル系捲縮短繊維単独でも嵩高であること、反撥性が発揮されることが必要である。単独の嵩高性（JIS Ｌ−1097）は、0.5g/cm²の荷重下で35cm³/g以上120cm³/g以下、10g/cm²の荷重下で15cm³/g以上60cm³/g以下あることが好ましく、さらに好ましくは、それぞれ、40cm³以上100cm³/g以下、20cm³/g以上50cm³/g以下であることが必要である。これらの嵩高性が低いと、得られた繊維成型クッション材の弾力性や圧縮反撥性が低いといった問題が顕著になってくる。
該捲縮短繊維は、その繊度が１〜100デニールの範囲が好ましく、さらに好ましくは、２〜50デニールである。繊度が１デニールより小さいと嵩高性が発揮されず、空気などによって側地内に吹き込まれたときに圧縮されて旨く均一に吹き込みにくくなり、得られたクッション材のクッショク性や反撥力が乏しくなっいしまう。また100デニールよりも大きくなると繊維が曲がりにくく構造体化が難しく、得られた繊維構造体の構成本数が少なく成り過ぎ、風合いが硬くなってしまう。またそのカット長は、10〜100mmの範囲内にあることが好ましく、特に15〜95mmの範囲内にあることが好ましい。
本発明の熱接着性複合繊維は、高弾性繊維球状体を得るのに有用である。この場合、本発明の熱接着性複合繊維と、マトリックスとなる非弾性ポリエステル系捲縮短繊維との混率を重量比（％）で、５〜49:95〜５の範囲にすることが好ましい。この熱接着性複合繊維の混率が高すぎると、該繊維球状体の中に形成される熱固着点の数が多すぎて、繊維球状体が硬くなりすぎてクッション材の材料にするには問題がある。逆に、該複合繊維の混率が低すぎると該繊維球状体の中に形成される熱固着点の数が少なすぎ、該繊維球状体の形態安定性に劣る。
また、前記非弾性ポリエステル系捲縮短繊維の表面には平滑材が処理され滑りやすい加工剤が処理されていることが好ましい。表面が滑りやすくなることによって空気乱流などによる繊維球状体化が行いやすくなる。また、得られた繊維球状体の風合いが柔らかく、羽毛やフェザータッチの風合いが得られやすくなる。これらの処理剤は、剤を付与した後、乾燥あるいは硬化処理することによって滑りやすくなる物であればなんでもよいが、例えばポリエチレンテレフタレートとポリエチレンオキシドのセグメント化ポリマーで被覆することにより表面摩擦を少なくすることが可能である。更に、シリコン系樹脂の平滑剤としてジメチルポリシロキサン、エポキシ変成ポリシロキサン、アミノ酸変性ポリシロキサン、メチルハイドロジエンポリシロキサン、メトキシポリシロキサン等のシリコン樹脂を主たる成分とする処理剤を任意の段階で付与することも平滑性を大幅に向上する面から考慮すると好ましい。該平滑剤の付着量は通常0.1〜0.3重量％が適当である。勿論シリコン樹脂中に帯電防止剤を添加したりシリコン樹脂処理後帯電防止剤処理を施すことは、繊維を球状体化する際の空気との摩擦や、融着処理する際の高温空気乱流処理などで静電気を防止するのに必要な場合が多いので所望に応じ、適宜添加すればよい。
この様な平滑化処理は一般的には、熱接着性複合繊維と非弾性ポリエステル系捲縮短繊維との熱接着を阻害することになるが、本発明で特定された熱接着性複合繊維は、ポリエチレンテレフタレートとポリエチレンオキシドとからなるポリマー被覆短繊維はもちろん、シリコン樹脂を付与した捲縮短繊維とも比較的よく融着し、しかも形態的に程よく非弾性ポリエステル系短繊維を螺旋状に抱え込み、見かけ状の接着強度をあげることが可能である。勿論、一般的な熱接着性の複合繊維ではこの作用は少ない。
本発明では、非弾性ポリエステル系短繊維の混率は、95〜51％の混率が好ましく、更に好ましくは90〜55％である。この混率が高すぎると、熱接着複合繊維の量が少なくなるので、熱固着点が少なくなるために反撥性が少なく、得られる繊維球状体は、形態安定性に劣る。
また、この混率が低すぎると、熱固着点が多すぎて、繊維球状体が硬くなりすぎ、クッション材の材料にするには問題がある。また、後から述べるように、熱処理により、非弾性ポリエステル系捲縮合成短繊維が、捲縮発現しながら熱固着点を形成するために、繊維球状体が高密度化し好ましくない。
本発明において、本発明の熱接着性複合繊維と非弾性ポリエステル系捲縮短繊維とを混綿し、後述する方法等で繊維球状体化をおこなう場合には、その繊維球状体表面には、非弾性短繊維や非弾性短繊維の毛羽が多く存在することが好ましい。この短繊維の毛羽が繊維球状体表面の平滑性に寄与し、該繊維球状体の吹き込み性能や、該繊維球状体が吹き込まれたあとのクッションの風合いを非常に良好なものとする。
また特に変形が大きいとき（ここで、特に変形が大きいとは、例えば、もとの中綿の厚みを基準として、50％の厚みになるような変形であることを言う。）には、始めに、隣り合う繊維同士が滑ることに起因する平滑な感触と、エラストマーにより形成された熱固着点の弾力性及び摩擦力の大きくなる感触が加わり、良好な風合いの中綿を製造することができる。
しかも、上記のような、大きな変形が繰り返されても、エラストマーにより形成された熱固着点が変形回復することにより、弾力性が維持されるとともに、耐久性も良好なものとなる。
高弾性繊維球状体の製造方法に際しては、まず、非弾性ポリエステル系捲縮短繊維と、本発明の熱接着性複合短繊維とを所定の混綿比率になるように配合し、均一に十分混綿されるように、ガーネットワイヤーが表面に張られた複数のローラが配設されたカードなどで、開繊と混綿を十分に行い、嵩高混綿塊を得る。
次いで、ブロワーの中に該混綿塊を吹き込み、所定時間乱流攪拌処理を行って、個々の短繊維を分繊・開繊しつつ、これらをを空気の渦流の中で滞留させて球状体化する。
ここで、非弾性ポリエステル系捲縮短繊維と熱接着性複合繊維とが均一に混綿・絡合された嵩高混綿塊が、空気や力学的な力を受けながら、特にその複合短繊維の特性から捲縮が進行しやすく、球状体が早く形成される。
また、この複合繊維の低融点熱可塑性エラストマーの融点以上、該ポリエステル系捲縮短繊維を構成するポリマーの融点未満の温度で熱処理を行い、繊維球状体中に熱固着点を形成することにより、弾力性、耐久性に優れた風合いに優れた繊維球状体が得られる。
また、前記の捲縮率は熱処理を行うことによっても進行するので、該球状体化の作用は一段と奏される。
このような作用を起こさせて繊維が球状体化を進めやすい方法であればいかなる方法を用いて本発明の高弾性球状体を製造してもよい。また、前記したように、非弾性ポリエステル系短繊維表面が平滑性をもち滑り易いほど球状体化がし易くなる。勿論、この球状体化処理の初期から熱風により、繊維球状体化と捲縮発現と低融点ポリマーを溶融させて融着を起こさせることの三者を同時に進める方法や、まず、該球状化の初期は常温で処理し、球状化の核が発生しはじめた時点で熱風を吹き込み、捲縮発現と融着とを起こすようにしたり、完全に球状化した後で、緩い熱風で捲縮発現と融着処理を行う方法など所望に応じ、採ることができる。
特に、非弾性ポリエステル系捲縮短繊維の捲縮発現性が、該複合繊維の捲縮発現性よりも低くく、非弾性ポリエステル系捲縮短繊維が繊維球状体の表面に出ており、且つ、この非弾性ポリエステル系短繊維が平滑表面を持っている態様は、繊維球状体が全体に平滑性を呈し、吹き込みやすく、吹き込まれたクッションの風合いもソフトで良好なものとなるので好ましい。
実施例
以下、実施例を挙げて本発明を更に詳細に説明する。
尚、実施例中の各値は、下記の方法により測定した。
固有粘度
オルトクロロフェノール溶媒中にサンプルを各種濃度［Ｃ］（g/100ml）で溶解させ、溶解している溶液について、35℃で測定した［ηsp（比粘度）/c］を濃度零に外挿した値［η］を固有粘度とした。
融点
DuPont社製 示差走査熱量計1090型を使用し、昇温速度20℃／分で測定し、融解ピーク温度を求めた。なお、この融解ピークが明確に測定出来ない場合には、微量融点測定装置（柳元製作所製）を用い、3gのサンプルを２枚のカバーグラスの間に挟み込み、ピンセットで軽く押さえながら、昇温速度20℃／分で昇温し、ポリマーの熱変化を観測した。その際、ポリマーが軟化して流動を始めた温度（軟化点）をここでは融点とした。
紡糸時の原糸収缶性
紡糸時に原糸を一旦缶に収納し、次のクリール工程まで運搬し、原糸を多数集束させて延伸機に供給するが、比較例２の原糸収缶量を100％とし、これを基準として、他の複合繊維の原糸収缶量を比較した。
延伸時、糸切れ
原糸を延伸中に一旦延伸機を停止し、第２温水浴内の延伸トウの単糸切れ本数を調べ、比較例２の単糸切れ本数を100％とし、これを基準として、他の複合繊維の糸切れ本数を比較したもの。
押し込み型クリンパー排出性
延伸後のトウを押し込み型クリンパーに供給し、捲縮付与後、クリンパーボックスからのトウの排出状態を目視で判定した。トウがクリンパーボックスから、問題なく自然に排出される場合を極めて良好とし、トウの詰まりはなくクリンパーボックスから排出され運転に支障はないが排出が僅かに不規則になる場合を良好とした。トウが詰まってクリンパーボックスから排出しない場合を不良と判定した。
原糸の膠着防止能
紡糸直後の原糸の膠着状態を目視で判定した。繊維同士が全く膠着しない場合、膠着防止能が極めて大とし、この膠着が少ないがやや存在する場合膠着防止能を大とし、膠着して固い針金状となっている場合、膠着防止能は不良と判定した。
エラストマー／ポリエステル間の界面接着強度
製造品の熱接着性複合繊維50本をランダム抽出し、電子顕微鏡により、その繊維横断面のエラストマー／ポリエステル間の界面剥離状態を目視で評価した。界面剥離を生じていない繊維が５本以内の場合を界面接着強度を大とし、界面剥離を生じている繊維が30本以上の場合を界面接着強度を小とした。
繊維間熱接着力
熱接着性複合繊維と、常法により得られた繊度が14デニール、繊維長が64mm、捲縮数が９個／インチの中空ポリエチレンテレフタレート短繊維とを重量比で30:70の割合で混綿し、カードスライバーを作成し、温度200℃で10分間、熱風循環式乾燥機で熱処理した後、スライバーを20mmの長さに切断し、カット両端を引張試験機に固定し、m/分の速さで切断したときの応力を測定した。比較例２の複合繊維を用いた場合の測定値を100％とし、これを基準として、他の複合繊維の場合と比較した値を示した。
捲縮弾性率
複合繊維の捲縮弾性率をJIS L1074により測定し比較例２の値を100％として基準とし、他の複合繊維の場合と比較した値を示した。
立体捲縮発現能
複合繊維を開繊し、カードに掛けてウエブ化し、縦横それぞれ10cmにカットし、熱風乾燥機で温度140℃で10分間、フリーな状態で熱処理し、JIS L1074に準拠し捲縮数を測定した。
開綿工程開繊性
複合繊維を、100gオープナー開綿工程を通過させた場合の未開繊部を分離し、重量測定し、比較例２を100％とし、これを基準として、他の複合繊維の未開繊部の重量を比較した。
カードシリンダー巻付
複合繊維をカード機に掛けたとき、定常状態で運転中に繊維の供給を停止し、供給停止した時から繊維がすべてカード機から排出されたときの繊維重量を測定する。比較例２の複合繊維の測定値を100％とし、これを基準として、他の複合繊維と比較した値を示した。
カードウエブ斑、ネップ
複合繊維をカード機に通し、カード機出口のウエブの状態を目視判定したもの。ウエブ斑やネップがない場合を極めて良好と、少ない場合を良好とし、多い場合を不良とした。
熱処理後の反撥性と耐久性
上述の繊維間熱接着力の測定の際の混綿ウエブを積層し、平板状で、温度200℃で、10分間熱循環式乾燥機で熱処理し、平板状に調整された密度0.035g/cm³、厚さ5cmの繊維構造体を作成し、断面積20cm²の平坦な下面を有する円柱ロッドで1cm圧縮し、その応力（初期応力）を測定し、これを反撥性とし、比較例２の複合繊維を用いた場合の測定値を100％とし、これを基準として、他の複合繊維と比較した値を示した。
この測定後に800g/cm²の荷重で10秒間圧縮したのち除重して、５秒間放置の操作を360回繰り返し、24時間後再び圧縮応力を測定した。
この初期応力に対する繰り返し圧縮後の応力の変化の比率を繊維構造体の耐久性とし、比較例２の複合繊維を用いた場合の値を100％とし、これを基準として、他の複合繊維と比較した値を示した。
熱処理後の硬さ斑
上述の熱処理後反撥性と耐久性の測定の際に作成した繊維構造体の表面を手で触れ、硬さ斑を官能評価した。表面の硬さに斑がない場合を、良とし、斑が多い場合を、不良とした。
実施例１並びに比較例１〜３
テレフタル酸とイソフタル酸とを85/15（モル％）で混合した酸成分とブチレングリコールとを重合し、得られたポリブチレン系テレフタレート45％（重量％）を更にポリブチレングリコール（分子量2000）55％（重量％）と加熱反応させ、ブロック共重合ポリエーテルポリエステルエラストマーを得た。この熱可塑性エラストマーの固有粘度は1.3、融点172℃であった。
この熱可塑性エラストマーと、ポリブチレンテレフタレートとを、第１図の三日月形状部にエラストマーを配すように、面積比で50/50になるように第３図に示すような複合紡糸口金（孔数260ホール）を使用し、紡糸油剤としてリウリルホスフェートカリウム塩を、繊維に対して0.05重量％付与して紡糸し、実施例１の複合繊維とした。この比較例として、第２図の（ａ）〜（ｃ）に示すような繊維断面になるように、（ａ）においてはサイドバイサイド型に複合し、（ｂ）においてはエラストマーが鞘成分となるように配し、（ｃ）においてはエラストマーが偏芯芯鞘型の鞘成分となるように配し、公知の口金で複合紡糸し、これらの複合繊維をおのおの比較例１、２、３とした。これらの未延伸繊維を２段階温水浴で、それぞれ温度を60℃、90℃、延伸倍率を2.5倍、1.2倍として、延伸し、次いでラウリルホスフェートカリウム塩を付与し、押し込み型クリンパーで機械捲縮を付与した後、温度60℃で乾燥し、64mmに切断した。
得られた繊維の物性は、太さが９デニール、油剤の付着率は0.2重量％であった。実施例１の複合繊維の繊維断面周率は35％で、曲率半径比Crは1.2、湾曲比Ｃは1.73、肉厚比Ｄは2.1であった。表１の表にこれらの複合繊維の製綿性複合繊維特性、開綿・カード性、繊維構造体特性についてまとめて示した。
製綿性に関して、比較例２、３では膠着が多いため、原糸収缶性、延伸糸切れが多く、クリンパーボックスからの排出性が悪いが実施例１では、比較例１並びにそれらの特性は良好であった。
複合繊維の特性に関して、比較例２、３では原糸の膠着防止の効果が小さく、多く膠着繊維が発生するので極めて太い繊維を形成しており、マトリックス繊維と混綿して、カードスライバーを熱処理したとき、該複合繊維の構成本数が事実上極めて少なく、繊維構造体としての接着強力は低いものとなる。一方、比較例１と、実施例１では原糸の膠着が少なく、該複合繊維が比較的均一に繊維構造体内部に分散するため接着強力が高くなる。比較例１と実施例１とを比較すると実施例１の方がより高い接着力を示し、良好であった。
複合繊維の捲縮特性に関して、比較例１ではポリエステル（Ｐ）成分が半月形状で扁平に近い断面形状である為と推定されるが捲縮弾性率が低い値を示している。このことが開綿工程での開繊性やカード性について後述の如く悪い影響を及ぼしている。比較例２、３および実施例１についてはほぼ同レベルの捲縮弾性率を示している。
また、比較例２では複合繊維の立体捲縮発現能が全くない。比較例１、２、実施例１は断面異方性があるため捲縮発現性能があるが比較例３では膠着による影響のため、立体捲縮発現能は低い。しかし、比較例１、並びに実施例１では膠着が少ないことと断面的特徴を持つのでで高いレベルの立体捲縮発現能を有する。開綿性、カード性に関して、比較例２、３では、膠着繊維が多いため、開綿しにくく、カード機のシリンダーへの巻付が多く発生し、ウエブの斑や、ネップが多く発生し、好ましくない。比較例１では複合繊維の捲縮弾性率が低いため繊維が束状形態となり開繊しにくく、カードシリンダー捲付が多く、カードウエブの斑やネップか多く好ましくない。
実施例１では膠着繊維が少なく、開綿時の開繊性は良好で、カード機のシリンダー巻付が少なく、ウエブの斑、ネップも少なく、良好であった。
繊維構造体特性に関して、比較例１、２、３では上述の如く、カードウエブの状態が良くなく、接着力が低く、反発性が低いものであり、硬さ斑も大きいものであり、実用上問題となるものであった。
実施例１では、開綿性、カード性共に、良好で、熱処理時の接着力が高く、また同時立体捲縮がより多く発現するため、反撥性、耐久性共に良好で、硬さ斑の少ない、良好な繊維構造体が得られた。
実施例２
実施例１の紡糸油剤と延伸油剤をラウリルホエフェートカリウム塩からポリエステルポリエーテル系ブロック共重合体の分散液に変更する以外は実施例１と同様に処理して複合繊維を得て、各種特性評価を行った。
尚、このとき、ブロック共重合体として、テレフタル酸／イソフタル酸／エチレングリコール／ポリエチレングリコールブロック共重合体（テレフタレート単位：イソフタレート単位＝70:30、テレフタレート単位＋イソフタレート単位：ポリエチレングリコール単位＝5:1、ポリエチレングリコール分子量＝2,000、ブロック共重合体の平均分子量＝10,000）と界面活性剤POE（10モル）ノニルフェニルエーテルサルフェーカリウム塩とを80:20の割合で配合した有効成分10％の水性分散液を使用した。
この結果を表２に示した。
実施例１では、紡糸集束時に膠着気味であったが膠着が全くなくなり、より良好な諸特性が得られた。
このように、非晶性ポリエーテルエステル系ブロック共重合体を複合繊維に付与することにより、膠着防止効果が更に改善された理由としては、以下の様に推察される。即ち、該ブロック共重合体は微細な粒子として分散しており、紡糸時の糸条集束前または集束中に繊維間に介在してコロの役目を果たし、繊維間の摩擦を減らすためと推定される。また該ブロック共重合体を微粒子として、水中に分散しているため複合繊維が、延伸可能な高い温度に加熱されたときでも、膠着現象が認められず、延伸性の向上にも寄付していると推案される。結果を表２に合わせて示す。
実施例３〜８
実施例１において、ポリマーの吐出比、紡糸口金仕様を変更して表３の表に記載の様な繊維断面形状の異なる熱接着性繊維を製造すること以外は実施例１と同様の操作を行いそれらの特性を評価した。
その結果、実施例３〜８の全ての場合において、製綿性に関して述べるならば原糸の膠着は少なく、不織布工程での開繊性、カード通過性は良好であり、熱成形することにより得られた繊維構造体の繊維間における接着力、反撥性、耐久性共に良好であり、硬さ斑の少ない良好な繊維構造体が得られた。
実施例９
実施例１において用いた熱接着性複合繊維と非弾性ポリエステル系捲縮短繊維とを用い、該複合繊維を繊維球状体の重量を基準として30％と、該捲縮短繊維70％とを混綿したのち、ローラーカードに２回通過させて、混綿嵩高綿を得た。
この嵩高綿を、ダクトで結ばれたブロワーと貯綿ボックスを有する装置に投入し、ブロワー内で、空気流による30秒間の撹袢を行って球状化した綿を得た。この後、該球状化綿を貯綿ボックス内に移送し、195℃の温度を有する弱い空気流によって、該球状化綿を撹袢しながら、弾性熱可塑性エラストマーを溶融させて、球状化した綿の内部に熱固着点を形成させ、その後、室温の空気をこの貯綿ボックス内に送り込んで冷却処理を行い、高弾性繊維球状体を得た。
この繊維球状体を顕微鏡を用いて観察したところ、該球状体表面には、非弾性ポリエステル系捲縮短繊維が70％の以上の確率で観察された。また、吹き込み機を用いて、クッション側地内に吹き込んでみたところ、吹き込みのトラブルがなく良好であって、得られたクッションの感触もソフトで弾力性がよく、８万回の圧縮硬さ保持率55％であって、シリコンを表面に付与した綿の35％や、表面にポリエチレンテレフタレートとポリエチレンオキシドのセグメント化ポリマーエマルジョンを付与し固化させた綿をつめたクッション材の32％よりはるかに高かった。
また、圧縮硬さは、2.2kgであって、上記シリコン綿、エマルジョン表面固化綿の0.6kgや0.9kgより高く、2.2kgでありソフトな感触でありながら反撥性が高く良好であった。
比較例４
実施例９において、弾性熱可塑性エラストマーから代えて、テレフタル酸とイソフタル酸とを全酸成分を基準として、モル比で60:40の割合で混合したジカルボン酸成分と、エチレングリコールとジエチレングリコールとを全ジオール成分を基準として、モル比で85:15の割合で混合したグリコール成分とから共重合した低融点のポリエステル系ポリマー（融点110℃、固有粘度0.78）を用いること以外は、実施例９と同様の操作を行って繊維球状体を得た。
ここで得られた繊維球状体は８万回の圧縮テスト後に調べたところ、固着点の剥離破壊が激しく起こっていた。更に、８万回圧縮硬さ保持率は15％と非常に悪く、弾力性が無く、風合いも極めて悪かった。

産業上の利用可能性
本発明の熱接着性複合繊維は、結晶性のＥ成分を一成分としているが、該複合繊維の製造時に不可避的に生じ、繊維の取り扱い性、工程特性さらに本来の接着性までをも阻害する膠着現象を解消することと、ポリマー間の界面接着強度、本来の接着性能並びに捲縮弾性との共存を達成せしめたものであり、各種クッション材例えば家具、ベッド、詰綿、寝具、座席のクッション、キルティングウエアの中綿、衛生材料・医療等の不織布、衣料用布帛、カーペット、車輌内装材等の原綿として好適に用いることができる。
更に、本発明の熱接着性複合繊維をバインダーとして用いた繊維球状体は、吹き込み特性に優れているので、得られるクッション材や詰め物が嵩高性に優れ、弾力性が高く、風合いもソフトで、圧縮耐久性に優れたクッション材や、枕等の中綿詰め物体として好適に用いることができる。Technical field
TECHNICAL FIELD The present invention relates to a heat-adhesive conjugate fiber, and more particularly, to minimize the agglomeration phenomenon between fibers in a process after spinning, as well as excellent elasticity, compression recovery durability and high air permeability. The present invention relates to a high elasticity heat-adhesive conjugate fiber capable of providing a fiber structure having
Here, the “sticking phenomenon” refers to a phenomenon in which fibers are physically and chemically bonded to each other by fusion, adhesion, fixation, and the like. Due to this "sticking phenomenon", the fibers are fused and pressure-bonded to each other, which adversely affects the production and processing of the fibers.
Background art
As a composite fiber comprising a crystalline thermoplastic elastomer and a crystalline thermoplastic polyester, Japanese Patent Publication No. 60-1404 discloses a side-by-side type or a non-elastic polyester comprising a block polyester polyether and an inelastic polyester containing polybutylene terephthalate as a main component. There is disclosed a high crimping conjugate fiber which is suitably used for outerwear and underwear which is conjugated and spun into a core-sheath type.
JP-A-3-185116 discloses that a polyester ether-based elastomer and an inelastic polyester mainly composed of polyethylene terephthalate are compound-spun in a side-by-side type or a core-sheath type, which has high crimpability, easy card opening, and stretchability. A heat-adhesive conjugate fiber that can be suitably used for producing a nonwoven fabric is disclosed.
JP-A-3-220316 discloses a method of producing a spun yarn and a heat-bondable nonwoven fabric having a card component and an improved spinnability in which a polyester elastomer is disposed in a sheath component and an inelastic polyester is disposed in a core component. Substantially concentric sheath-type heat-adhesive conjugate fibers have been proposed that are useful for this purpose.
Further, regarding a heat-adhesive conjugate fiber in which a thermoplastic elastomer is disposed on the fiber surface and a fiber structure obtained using the same, published patents WO91 / 19032, JP-A-4-240219, and JP-316629A are also disclosed. JP-A-5-98516, JP-163654, JP-A-177065, JP-A-261184, JP-A-302255, JP-A-320103, JP-A-337258, and JP-A-6-272111. And JP-A-306708.
As shown in FIGS. 2 (a) to 2 (c), the cross-sections of the various heat-adhesive conjugate fibers disclosed in the prior art listed above are literally side-by-side type and eccentric core-sheath type. In this case, the thermoplastic elastomer and the inelastic polyester are combined in an area ratio of 20/80 to 80/20.
By the way, in the case of a conjugate fiber using an elastomer as one component, due to the nature of the elastomer, the above-mentioned sticking phenomenon between the conjugate fibers occurs inevitably after the spinning step, causing a great deal of problems.
In this sense, none of the above-mentioned prior arts describes anything about obtaining a conjugate fiber having improved adhesiveness, elasticity, and crimp development while overcoming the sticking phenomenon between fibers. There is no suggestion that recognizes. However, in Japanese Patent Application Laid-Open No. 5-302255, regardless of the recognition or non-recognition, when a polyester-based elastomer having a different composition is composite-spun into a core-sheath type to obtain a long fiber, the adhesive property is large, but the elastic property is high. It has been proposed that an excellent elastomer containing a large amount of a polyether component is disposed in a core component, and an elastomer having a small adhesiveness but a low elasticity and a small amount of a polyether component is disposed in a sheath component to perform composite spinning. However, such a material does not provide a practical level of anti-sticking effect. In addition, the use of the composite fiber is a material for a nonwoven fabric which is useful for a pulp material, an interlining, a supporter, an elastic tape, and the like.
In turn, the overall performance of the conventional heat-bonded conjugate fiber shown in FIGS. 2 (a) to 2 (c), namely, anti-sticking ability, interfacial adhesive strength between elastomer / polyester polymer and original heat adhesion and crimping Table 1 shows the elasticity.

The evaluation in Table 1 is a relative evaluation based on the composite fiber (b). However, in the table, “*)” indicates the case of a polyester elastomer, and “**)” indicates the case where it is assumed that there is no sticking.
According to the table, the conjugate fiber (c) is excellent in four requirements out of the five required properties (corresponding to 4) to 8) in the conjugate fiber). I can see. However, the "small", or poor, anti-stick properties of the fibers, as described below, have a fatal disadvantage to the industrial manufacturing process and the quality of the resulting product.
That is, the conjugate fiber is first collected as an undrawn raw yarn in a winder or a raw tow can, but is not sufficiently cooled, and when the single fibers are bundled together, an agglomeration due to the elastomer occurs. Even in a state where the fibers are stored, there is a problem that the fibers adhere to each other to form a hard string or that the subtows are firmly fixed to each other and cannot be unwound from the winder.
In addition, even when collected in an original tow can, there is a problem that the amount of can collected is significantly reduced due to the stringy and firm adherence, and the productivity is significantly reduced. In the stretching step, the stretched sub-tow having a string-like shape has extremely poor stretchability, and frequently causes thread breakage and winding of a stretching roller, so that stable production cannot be performed. Even if heat-adhesive fibers can be produced, the fibers adhere to each other as a group. Since the number of effective fixing points that are effective for adhering is small, the adhesiveness is remarkably low, there is no elasticity, and the fibrous structure is easily broken by external force, resulting in a non-durable one. There is a problem.
On the other hand, the conjugate fiber (a) doubles in the anti-sticking ability as compared with the conjugate fiber (b) or (c), but has a problem that the heat bonding function and the crimp elasticity which are the original objects are remarkably inferior. I have
Disclosure of the invention
An object of the present invention is to cause a sticking phenomenon which is inevitably generated during the production of a thermo-adhesive conjugate fiber in which a crystalline thermoplastic elastomer is disposed as one component, which impairs fiber handling properties, process characteristics and even the original thermo-adhesive performance. And the coexistence of interfacial adhesive strength between polymers, original adhesive performance and crimp elasticity, which have been left unsolved until now.
Still another object of the present invention is to provide a cushioning material or a high elastic fiber ball having excellent blowing properties, excellent bulkiness, soft texture, high elasticity, and excellent compression recovery durability. To provide a heat-adhesive conjugate fiber.
According to the study of the present inventors, the above object is desirable when the elastomer component is arranged in a crescent shape in the cross section of the heat-adhesive conjugate fiber and the geometric dimension at that time is specified as shown below. It was found that a composite fiber of
That is, in the present invention, the crystalline thermoplastic elastomer (E) and the crystalline inelastic polyester (P) having a melting point higher than that of the elastomer (E) are mixed in a circular fiber cross section with E: P = 20. : 80 to 80:20 in a composite fiber arranged in an area ratio,
The cross section and surface of the fiber are specified by the following requirements (1) to (5).
Requirements
{Circle around (1)} In the fiber cross section, the elastomer (E) is arranged in a crescent shape formed by two arcs having different radii of curvature, and has a curve (r) having a large radius of curvature.₁) Forms part of the outer circumference;
{Circle around (2)} The polyester (P) has a curve (r) having a smaller radius of curvature among two curves forming a crescent shape in a fiber cross section._Two) Along with the elastomer, while the curve with the larger radius of curvature (r₁) Is that a part of the fiber surface is formed in an arc shape so that the circumference R is in the range of 25 to 49% so as to be an outer peripheral line;
(However, the circumferential ratio R complies with the following definition.₁), The entire circumference (L₁+ L_Three) (L_Three), And the peripheral ratio R is [R = ｛(L_Three) / (L₁+ L_Three)｝ × 100 (%)]. )
(3) The radius of curvature (r₁) And radius of curvature (r_Two) And the ratio (r₁/ r_Two) Is in a range from more than 1 to 2 or less;
(4) The radius of curvature (r_Two) The curvature ratio C of the curve is in the range of 1.1 to 2.5;
(However, the curvature ratio C complies with the following definition. In FIG. 1, (r_Two) With an arc (L)_Two) Length and (r₁) And the arc (L_Two) Between contacts (P₁−P_TwoBetween the length (L) and the length (L), and the curvature ratio C is ΔC = (L_Two) / (L)}. )
(5) The thickness ratio of the elastomer (E) to the polyester (P) is in the range of 1.2 to 3;
(However, the thickness ratio D complies with the following definition. In FIG. 1, (r₁) And the center of the circle with radius (r)_Two), The length (L) of the polyester (P) component in a straight line_P) And the length of the elastomer (E) component (L_E), And the thickness ratio D is ΔD = (L_P) / (L_E) Calculated by｝. )
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a fiber cross section of the heat-adhesive conjugate fiber of the present invention,
FIGS. 2 (a), (b) and (c) are schematic diagrams showing fiber cross sections of conventional heat-adhesive conjugate fibers, respectively.
FIG. 3 is a schematic view showing a longitudinal section of a composite spinneret for producing the heat-adhesive composite fiber of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The requirements (1) to (5) required to achieve the object of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example (here, a perfect circle) of a cross section of a heat-adhesive conjugate fiber which has solved the problem of the present invention.
In FIG. 1, E indicates a crystalline thermoplastic elastomer, and P indicates a crystalline inelastic polyester. What is characteristic here is that the cross section has a radius of curvature (r₁), The E component is (r₁), (R_Two) Are arranged in a crescent shape formed by two arcs with different radii of curvature.₁) Is the radius of curvature (r₁), And constitutes a part of the fiber cross section as it is, while the P component has a smaller radius of curvature of the two curves forming the crescent shape in the fiber cross section (r_TwoAlong with the elastomer. And the P component is also the outer line (L_Three), A part of the fiber surface is formed._Three), The fiber cross-sectional circumference R [R = (L_Three) / ｛(L₁) + (L_Three) × 100 (%)] must be in the range of 25 to 49%, preferably 28 to 40%. If this R is lower than 25%, the fibers are easily fused and pressed together when producing a conjugate fiber, and sticking occurs to easily cause trouble in production. In addition, because the E component is soft, it will bite into the rotating garnet wire used for fiber opening and blending, etc. Become. Also, the adhesive part (L₁) Is increased, so that the number of heat fixation points with surrounding fibers is increased, and a fine network structure is formed, making it difficult to obtain elasticity. On the other hand, if this R exceeds 49%, the area covered by the heat-sealing component on the fiber surface decreases from the viewpoint of the adhesive function, and it becomes difficult for desired adhesion to occur.
In such a cross section, the radius of curvature (r₁) And (r_Two) And ｛(r₁) / (R_Two) The curvature radius ratio Cr, which is｝, needs to be larger than 1.
When the Cr value is 1 or less, the interface between the E component and the P component, which is a joining line, is easily peeled off. Once peeled, the adhesive strength between fibers is greatly reduced, the ability to develop three-dimensional crimps is reduced, and the crimps are reduced. Is undesirably reduced. In addition, the crimp elastic modulus of the conjugate fiber decreases, and unfavorable problems such as poor fiber opening in the cotton-opening process, frequent occurrence of card cylinder winding, occurrence of card web spots, and occurrence of nep.
On the other hand, if the Cr value exceeds 2, the area occupied by the E component with respect to the fiber cross section becomes too large, which is not preferable.
Next, in the composite form described above, the degree of curvature C relating to the joining line between the E component and the P component, that is, in FIG._Two), The point (P₁) And point (P_Two) And the ratio of the line segment (L) connecting を C = (L_Two) / (L)｝ must be in the range of 1.1 to 2.5, preferably 1.2 to 2.0.
When the value of C is lower than 1.1, for example, in a conventional composite form as shown in FIG. 2 (a), the polymers are liable to be separated from each other, so that the appearance of crimp is reduced, and the crimp by heat treatment is reduced. The expression is reduced, and it becomes difficult to form a flexible heat-fixed point involving the inelastic crimped short fibers. On the other hand, when the value of C exceeds 2.5, crimping becomes too large, crimping in heat treatment is extremely likely to occur, the bulk of the fibrous structure is reduced, and the feeling of “go-rough” appears. Not preferred. Here, the “ruffled” feeling means an unpleasant touch when the surface of the fibrous structure is touched, as if a small and hard foreign substance is present in the structure.
Finally, it is also very important to specify the thickness ratio (D) between the E component and the P component. This D is the maximum thickness length of the E component in FIG._E), The maximum thickness of the P component is (L_P), ｛D = (L_P) / (L_E)｝, And this value must be in the range of 1.2 to 3.0, preferably 1.5 to 2.9. When D is lower than 1.2, the appearance of crimp is reduced, the appearance of crimp is reduced by heat treatment, and similarly, it is difficult to form a fibrous structure. It is not preferable that fusion occurs while involving inelastic crimped short fibers. . On the other hand, when D exceeds 3.0, crimping becomes too large, crimping due to heat treatment is extremely likely to occur, and the bulk and the like become small.
In the present invention, the melting point of the P component is preferably 10 to 190 ° C. higher than the melting point of the E component. In this way, when the composite fiber is thermally bonded, only the E component is subjected to a heat treatment at a temperature equal to or higher than the melting point of the E component and lower than the melting point of the P component to be thermally melted. , The adhesion strength is maintained at a high level, and the elasticity and durability can be improved.
Here, the P component is not particularly limited as long as it is a polyester, but is usually polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, polypivalolactone. Alternatively, it is a polymer composed of a copolymer ester of these, but polybutylene terephthalate, in which distortion is hardly left, is preferably used because the application is subject to repeated distortion. In particular, when the hard segment of the elastomer used for the fusion component of the conjugate fiber is a polybutylene-based material, there is no problem such as peeling, which is favorable. The melting point of the P component is preferably in the range of 110 to 290 ° C.
On the other hand, the melting point of component E is suitably in the range of 100 to 220 ° C. If the temperature is lower than 100 ° C., even if the fiber is spun so as to satisfy the requirements (1) to (5) of the present invention, it may not be possible to completely prevent sticking of the fibers during spinning. In addition, when the composite fibers are stacked in multiple tiers in a warehouse having no tone control device in summer, for example, there is a concern that the fibers may stick together. When the temperature exceeds 220 ° C., the upper limit of the stabilization temperature of the heat treatment machine is full, and the adhesive strength becomes partially uneven, causing unevenness in hardness. C is a more desirable range in terms of prevention of sticking, stability in heat treatment, and the like.
As the E component, polyurethane-based elastomers and crystalline polyester-based elastomers are preferable in terms of spinning aptitude and physical properties.
As the polyurethane elastomer, a low melting point polyol having a molecular weight of about 500 to 6000, such as dihydroxy polyether, dihydroxy polyester, dihydroxy polycarbonate, dihydroxy polyester amide, and the like, and an organic diisocyanate having a molecular weight of 500 or less, such as P, P-diphenylmethane diisocyanate, Trisine diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, 2,6-diisocyanatomethylcaproate, hexamethylene diisocyanate, etc., and a chain extender having a molecular weight of 500 or less, for example, a reaction with a glycol, amino alcohol or triol. The resulting polymer can be mentioned. Among these polymers, particularly preferred are polytetramethylene glycol or poly-ε-caprolactone as the polyol. As the organic diisocyanate, p, p'-diphenylmethane diisocyanate is preferred. As chain extenders, p, p'-bishydroxyethoxybenzene and 1,4-butanediol are preferred.
On the other hand, as the crystalline polyester-based elastomer, a polyetherester block copolymer obtained by copolymerizing a thermoplastic polyester as a hard segment and a poly (alkylene oxide) glycol as a soft segment, more specifically, terephthalic acid, Aromatics such as isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and sodium 3-sulfoisophthalate Aliphatic dicarboxylic acids such as aliphatic dicarboxylic acids, alicyclic dicarboxylic acids such as 1,4-dichlorohexane dicarboxylic acid, succinic acid, oxalic acid, adipic acid, sebacic acid, dodecane diacid, and dimer acid, or ester-forming derivatives thereof At least one dicarboxylic acid selected from Aliphatic diols such as butanediol, diethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, and decamethylene glycol; or 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol , A cycloaliphatic diol such as tricyclodecane dimethanol, or at least one diol component selected from ester-forming derivatives thereof, and polyethylene glycol, poly (1,2-propylene) having an average molecular weight of about 300 to 5,000. Oxide) glycol, poly (1,3-propylene oxide) glycol, poly (tetramethylene oxide) glycol, copolymer of ethylene oxide and propylene oxide, ethylene oxide and tetrahydroxide It is preferred poly copolymer of furan (alkylene oxide) of the glycol is a terpolymer composed of at least one.
However, from the viewpoint of properties such as adhesiveness and heat resistance with polyester-based composite components, and physical properties such as strength, a polyetherester block copolymer having polybutylene-based terephthalate as a hard segment and polyoxytetramethylene glycol as a soft segment is particularly preferred. . In this case, in the polyester portion constituting the hard segment, the copolymerization ratio based on the total acid component of the copolymer (indicating mol% based on the total acid component) is 40 to 100 mol% of terephthalic acid, and isophthalic acid. Containing from 0 to 50 mol% is used. Acid components other than terephthalic acid and isophthalic acid include phthalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, and 1,4-cyclohexanedicarboxylic acid Is preferably used in order to obtain a predetermined melting point and to improve quality such as elasticity and durability. In particular, those containing 50 to 90 mol% of terephthalic acid and 10 to 35 mol% of isophthalic acid are more preferably used.
The main component of the glycol component of the polyester portion is preferably 1,4-butanediol. Here, "main" means that 80 mol% or more of all glycol components is 1,4-butanediol, and other glycol components may be copolymerized within a range of 20 mol% or less. That means. Preferred examples of the copolymerized glycol component include ethylene glycol, trimethylene glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. be able to.
Further, the polyetherester block copolymer has an average molecular weight of 300 to 5000 and contains a poly (alkylene oxide) glycol component of 5 to 80% by weight, and has an average molecular weight of 800 to 4000 and contains a glycol component of 30 to 70% by weight. Is particularly preferred. When the average molecular weight is less than 300, the blockability of the obtained block copolymer is reduced and the elastic recovery performance becomes insufficient. On the other hand, when it exceeds 5,000, the copolymer of the poly (alkylene oxide) glycol component is It is not preferable because the polymerizability decreases and the elastic recovery performance becomes insufficient.
When the copolymerization amount of the glycol component is less than 5% by weight, even if the composite fiber is subjected to heat bonding treatment to form a cushion material or the like, the object having good elastic properties aimed at by the present invention cannot be obtained. On the other hand, if it exceeds 80% by weight of the glycol component, the mechanical properties, heat resistance and light resistance of the resulting block copolymer are undesirably reduced.
The poly (alkylene oxide) glycol preferably used is preferably a homopolymer of polyethylene glycol, poly (propylene oxide) glycol, or poly (tetramethylene oxide) glycol. Further, a random copolymer or a block copolymer in which two or more of the repeating carriers constituting the homopolymer are copolymerized in a random or block manner may be used, or the homopolymer or the copolymer may be used. A mixed polymer in which two or more of the above are mixed may be used. Such a polyetherester block copolymer can be obtained by using a known method for producing a copolyester.
In producing the conjugate fiber of the present invention, each of the E component and the P component is usually dried until the water content becomes 0.1% or less, and then subjected to spinning.
A method of producing a fiber by combining a crystalline thermoplastic elastomer with an inelastic polyester can be performed by a well-known spinning apparatus and method.
Referring to the drawings, the composite fiber of the present invention can be obtained by using a composite die as shown in FIG. 3, for example. In the composite die of FIG. 3, the P component was flowed in a molten state from the pin 3 provided on the upper plate 1, and the E component was flowed in a molten state between the upper plate 1 and the lower plate, and provided on the lower plate 2. The nozzles 4 discharge the composite. At the time of spinning, the composite fiber yarn cooled and solidified after discharge of the polymer can be taken out by applying a spinning oil agent, or can be subsequently drawn 2 to 5 times to be taken out.
Here, the reason that the composite fiber having the fiber cross section shown in FIG. 1 is formed by using the spinneret shown in FIG. 3 can be explained by the difference in melting point between the P component and the E component. I can do it.
That is, since the difference between the melting points is directly related to the melt viscosity, at the same temperature, the P component has a higher viscosity (that is, hard), and the E component has a lower melt viscosity (that is, the melt viscosity is lower). soft).
That is, the molten P component flowing from the pin 3 flows in the vertical direction as it is, without being substantially affected by the discharge pressure of the molten E component, and pushes the lower E2 component while pushing the surrounding E component. Contact. Further, the fibers are finally discharged from the nozzles 4 along the lower plate 2 to form a fiber cross section as shown in FIG.
It is remarkable as an anti-sticking measure to interpose an amorphous polyester / polyether-based block copolymer as a spinning oil agent between single fibers before or during bundle immediately after spinning. effective.
At the same time, the drawability of the conjugate fiber is improved, and when the fiber structure is formed by passing through the card, the fiber is originally soft and the cardability is remarkably inferior. In the range of 0.02 to 5% by weight, based on the weight of the fiber, improves the smoothness of the fiber, and also improves the wettability of the molten polymer during thermal bonding. , Durability is greatly improved.
If the amount of the amorphous polyetherester block copolymer is less than 0.02% by weight based on the weight of the fiber, it is insufficient to obtain the effects of preventing sticking, improving cardability and improving adhesive strength. On the other hand, if the amount of adhesion exceeds 5% by weight, even if the amount of adhesion of the amorphous polyester polyether block copolymer is increased, effects such as prevention of sticking, improvement of cardability, and improvement of thermal adhesion are obtained. On the contrary, the adhesiveness of the fiber surface increases, the adhesive wrapping occurs in a card machine, a uniform fiber structure cannot be obtained, and unevenness in hardness occurs, which is not preferable.
This amorphous polyetherester-based block copolymer can be obtained from terephthalic acid and / or isophthalic acid and / or metasodium sulfoisophthalic acid or their lower alkyl esters, lower alkylene glycols, and polyalkylene glycols and / or polyalkylene glycols. It is a polyetherester block copolymer composed of an alkylene glycol monoether.
For example, terephthalic acid-alkylene glycol-polyalkylene glycol, terephthalic acid-isophthalic acid-alkylene glycol-polyalkylene glycol, terephthalic acid-alkylene glycol-polyalkylene glycol monoether, terephthalic acid-isophthalic acid-polyalkylene glycol-polyalkylene glycol mono Ether, terephthalic acid-metasodisulfoisophthalic acid-alkylene glycol-polyalkylene glycol, terephthalic acid-isophthalic acid-methasdium sulfoisophthalic acid-alkylene glycol-polyalkylene glycol, and the like. The ratio of units to isophthalate units and / or metasodium sulfoisophthalate units is from 100: 0 to 50:50 (mo Is preferable in order to prevent adhesion during spinning. Furthermore, in order to enhance the anti-sticking ability of the conjugate fiber provided with the block copolymer, the ratio of the terephthalate unit to the isophthalate unit and / or the metasodium sulfoisophthalate unit is preferably from 90:10 to 50:50 (mol Ratio) is particularly preferred.
In the block copolymer, the ratio of the terephthalate unit and the isophthalate unit or / and the methasium sulfoisophthalate unit to the polyalkylene glycol unit is usually from 2: 1 to 151 (molar ratio), In consideration of preventing the occurrence of adhesion between single fibers and improving the adhesive strength of the fibers, the ratio is particularly preferably 3: 1 to 8: 1 (molar ratio).
Here, the alkylene glycol used for producing the amorphous block copolymer is an alkylene glycol having 2 to 10 carbon atoms such as ethylene glycol, propylene glycol, tetramethylene glycol, and decamethylene glycol, and polyalkylene glycol is usually used. Average molecular weight is 600 to 12,000, preferably average molecular weight, 1,000 to 5,000 polyethylene glycol, polyethylene glycol / polypropylene glycol copolymer, polyethylene glycol / polytetramethylene glycol copolymer, polypropylene glycol, etc., polyethylene glycol, polypropylene glycol, etc. Monomethyl ether, monoethyl ether, monophenyl ether and the like are preferable. However, monoethers of polyethylene glycol are particularly preferable from the viewpoint of improving the anti-sticking property between single fibers.
The average molecular weight of the amorphous block copolymer depends on the molecular weight of the polyalkylene glycol used, but is usually 2,000 to 20,000, preferably 3,000 to 13,000. If the average molecular weight is less than 2,000, the stretchability, prevention of adhesion and improvement of the thermal adhesive strength are insufficient. If it exceeds 20,000, the stretchability and the thermal adhesive strength are undesirably reduced. The polyalkylene glycol used to control the molecular weight during the polycondensation of the block copolymer is preferably one having one terminal group blocked, such as monomethyl ether, monoethyl ether, and monophenyl ether.
The amorphous block copolymer is prepared by using a surfactant such as an alkali metal salt of polyoxyethylene alkyl phenyl ether phosphate, an alkali metal of polyoxyethylene alkyl phenyl ether sulfate and / or an ammonium salt or alkanolamine salt thereof. Disperse. The aggregation start temperature of the amorphous block copolymer dispersion is preferably from 30 to 100 ° C, more preferably from 60 to 90 ° C. The amount of the amorphous block copolymer to be used is preferably 0.02 to 5.0% by weight, particularly preferably 0.1 to 3.0% by weight, based on the weight of the conjugate fiber.
The thermal adhesive conjugate fiber of the present invention preferably has a fineness in the range of 0.5 to 200 denier. When the denier is less than 0.5 denier, the adhesive strength becomes insufficient when the heat bonding treatment is performed as a fiber structure, and sufficient elasticity and durability cannot be obtained. As described above, even if the cross-sectional shape is specified, it is difficult to prevent sticking between the single fibers.
As a result, the bonding performance of the fibers is reduced, and the elasticity and durability are reduced. In particular, the range of 2 to 100 denier is preferable. The composite fiber of the present invention may be subjected to mechanical crimping by a press crimper after stretching, and the number of crimps is 5 to 25 / inch, and the degree of crimp is 5 to 30%. Is preferred. If the number of crimps is less than 5 / inch and the degree of crimp is less than 5%, the card web is cut during carding, and the bulk of the obtained fiber structure is unpreferably reduced. If the number of crimps exceeds 25 pieces / inch and the degree of crimp exceeds 30%, the passing property of the card machine becomes poor, and web unevenness and NEP frequently occur, which is not preferable. In particular, the number of crimps is preferably in the range of 8 to 20 pieces / inch, and the degree of crimp is in the range of 6 to 18%. Further, the cut length of the short fiber at that time is preferably in the range of 10 to 100 mm, and particularly preferably in the range of 15 to 95 mm.
The heat-adhesive conjugate fiber described above can be thermoformed into a nonwoven fabric or a sheet by itself, regardless of the shape of the long fiber or the short fiber, but the most preferable is an inelastic polyester. This composite fiber is dispersed and mixed in the form of a crimped short fiber in a fiber aggregate having a system crimped short fiber as a matrix, and thermoformed into a desired shape. This embodiment is typically disclosed in WO 91/19032 listed at the outset.
The non-elastic polyester crimped short fibers serving as a matrix may be any non-elastic polyester-based crimped short fibers having a helical or omega crimped shape or partially having such a shape. Inelastic polyester-based crimped short fibers are ordinary polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, polypivalolactone or a copolymer thereof. A crimped staple fiber composed of an ester or a blended body of those crimped staple fibers, or a side-by-side type fiber cross-section in which the degree of polymerization or the copolymerization component of two or more polymers of the above-mentioned polymers is changed is symmetrically configured, Composite short fibers exhibiting a spiral crimp. Of course, in order to exhibit crimping, it is also preferable that a fiber exhibiting helical or omega-type crimps during drawing and relaxation heat treatment by anisotropic cooling in which one side of the fiber is strongly cooled during spinning. The cross-sectional shape of these short fibers may be circular, flat, irregular or hollow.
In order for the crimped short fibers to serve as a skeleton of the fiber structure, it is necessary that the polyester-based crimped short fibers alone be bulky and exhibit rebound. Single bulkiness (JIS L-1097) is 0.5g / cm^Two35cm under load^Three/ g or more 120cm^Three/ g or less, 10g / cm^Two15cm under load^Three/ g more than 60cm^Three/ g or less, more preferably, each 40cm^ThreeMore than 100cm^Three/ g or less, 20cm^Three/ g or more 50cm^ThreeIt must be less than / g. When these bulkiness is low, the problem that elasticity and compression rebound of the obtained fiber molded cushion material are low becomes remarkable.
The fineness of the crimped short fibers is preferably in the range of 1 to 100 denier, more preferably 2 to 50 denier. If the fineness is smaller than 1 denier, the bulkiness will not be exhibited, and when it is blown into the side ground by air etc., it will be compressed and it will be difficult to blow it uniformly, and the cushioning material obtained will have poor cushioning properties and repulsion force I will. On the other hand, if it is larger than 100 denier, the fiber is difficult to bend and it is difficult to form a structure, and the number of constituents of the obtained fiber structure becomes too small, and the texture becomes hard. The cut length is preferably in the range of 10 to 100 mm, and particularly preferably in the range of 15 to 95 mm.
The heat-adhesive conjugate fiber of the present invention is useful for obtaining a highly elastic fiber sphere. In this case, it is preferable that the mixing ratio of the heat-adhesive conjugate fiber of the present invention and the non-elastic polyester crimped staple fiber serving as a matrix is in the range of 5 to 49:95 to 5 by weight ratio (%). If the mixing ratio of the heat-adhesive conjugate fiber is too high, the number of heat fixation points formed in the fiber sphere is too large, and the fiber sphere becomes too hard to be used as a cushioning material. There is. Conversely, if the mixing ratio of the composite fiber is too low, the number of heat fixing points formed in the fiber sphere is too small, and the shape stability of the fiber sphere is poor.
Preferably, the surface of the inelastic polyester crimped short fibers is treated with a smoothing agent and a slippery processing agent. When the surface becomes slippery, it becomes easier to form the fiber into a sphere due to air turbulence. Further, the texture of the obtained fiber spherical body is soft, and the texture of feather and feather touch is easily obtained. Any of these treating agents may be used as long as they become slippery by drying or curing after application of the treating agent. For example, coating with a segmented polymer of polyethylene terephthalate and polyethylene oxide reduces surface friction. It is possible. Further, a treatment agent containing a silicone resin as a main component, such as dimethylpolysiloxane, epoxy-modified polysiloxane, amino acid-modified polysiloxane, methylhydrogenpolysiloxane, or methoxypolysiloxane, is applied at an optional stage as a silicone resin leveling agent. This is also preferable from the viewpoint of greatly improving the smoothness. The suitable amount of the smoothing agent is usually 0.1 to 0.3% by weight. Of course, adding an antistatic agent to the silicone resin or applying an antistatic agent treatment after the silicone resin treatment will result in friction with air when spheroidizing the fibers and high-temperature turbulent airflow treatment during the fusion treatment. In many cases, it is necessary to prevent static electricity, so that it may be appropriately added as desired.
Such a smoothing treatment generally hinders the thermal adhesion between the heat-adhesive conjugate fiber and the inelastic polyester-based crimped staple fiber, but the heat-adhesive conjugate fiber specified in the present invention is: Not only polymer-coated short fibers consisting of polyethylene terephthalate and polyethylene oxide, but also crimped short fibers to which silicone resin has been applied are fused relatively well. It is possible to increase the adhesive strength. Of course, this effect is small with general heat-adhesive conjugate fibers.
In the present invention, the mixing ratio of the non-elastic polyester short fibers is preferably from 95 to 51%, more preferably from 90 to 55%. If this mixing ratio is too high, the amount of the heat-bonding conjugate fiber will be small, so that the heat fixation point will be small, so that the resilience will be small and the resulting fiber spherical body will have poor form stability.
On the other hand, if the mixing ratio is too low, the number of heat fixation points is too large, and the fiber spherical body becomes too hard, which is problematic for use as a cushioning material. In addition, as will be described later, the heat treatment causes the inelastic polyester-based crimped synthetic short fiber to form a heat-fixed point while exhibiting crimping, which is not preferable because the fiber sphere has a high density.
In the present invention, when the heat-adhesive conjugate fiber of the present invention and inelastic polyester-based crimped staple fiber are mixed and formed into a fiber spheroid by a method described below, the surface of the fiber spheroid is inelastic. It is preferable that many fluffs of short fibers and inelastic short fibers exist. The fluff of the short fibers contributes to the smoothness of the surface of the fiber sphere, and makes the blowing performance of the fiber sphere and the feel of the cushion after the fiber sphere have been blown very good.
Also, when the deformation is particularly large (here, the particularly large deformation means, for example, a deformation in which the thickness becomes 50% based on the thickness of the original batting). In addition, a smooth feel caused by slipping between adjacent fibers and a feeling that elasticity and frictional force of a heat fixing point formed by the elastomer are increased are added, so that it is possible to manufacture batting with a good texture.
In addition, even if the above-described large deformation is repeated, the heat fixation point formed by the elastomer recovers from the deformation, whereby the elasticity is maintained and the durability is improved.
In the method for producing the high elastic fiber spherical body, first, the inelastic polyester crimped staple fiber and the heat-adhesive conjugate staple fiber of the present invention are blended so as to have a predetermined cotton mixing ratio, and are uniformly mixed sufficiently. As described above, by using a card or the like in which a plurality of rollers each having a garnet wire stretched on its surface are provided, the spreading and blending are sufficiently performed to obtain a bulky blended cotton mass.
Next, the mixed cotton mass is blown into a blower, and a turbulent agitation process is performed for a predetermined time to separate and open individual short fibers, while retaining them in a vortex of air to form spheroids. I do.
Here, the bulky cotton swollen lump in which the inelastic polyester-based crimped staple fibers and the heat-adhesive conjugate fibers are uniformly mixed and entangled is subjected to air or mechanical force, and particularly, from the properties of the conjugate staple fibers. Shrinkage easily progresses, and a spherical body is formed quickly.
Further, heat treatment is performed at a temperature equal to or higher than the melting point of the thermoplastic elastomer having a low melting point of the conjugate fiber and lower than the melting point of the polymer constituting the polyester-based crimped staple fiber, thereby forming a heat fixing point in the fibrous spherical body. A fiber sphere having excellent texture and excellent durability can be obtained.
Further, since the above-mentioned crimping ratio also advances by performing heat treatment, the effect of the spheroidization is further exhibited.
Any method may be used to produce the highly elastic spherical body of the present invention, as long as the method facilitates the formation of spheroidal fibers. Further, as described above, as the surface of the non-elastic polyester short fiber has smoothness and is more slippery, the spheroid becomes easier to be formed. Of course, from the beginning of the spheroidizing treatment, hot air is used to simultaneously promote the three steps of fiber spheroidization, crimping, and melting of the low-melting polymer to cause fusion. Initially, it is treated at room temperature, and when hot spheroids begin to be generated, hot air is blown in to cause crimping and fusing, or after complete spheroidizing, crimping occurs with gentle hot air. Any method such as a method of performing a fusion treatment can be employed.
In particular, the crimping property of the inelastic polyester-based crimped staple fiber is lower than the crimping property of the conjugate fiber, and the inelastic polyester-based crimped staple fiber is exposed on the surface of the fibrous spherical body. The mode in which the inelastic polyester short fiber has a smooth surface is preferable because the fiber spherical body exhibits smoothness as a whole, is easily blown, and the texture of the blown cushion is soft and good.
Example
Hereinafter, the present invention will be described in more detail with reference to examples.
In addition, each value in an Example was measured by the following method.
Intrinsic viscosity
Samples were dissolved in orthochlorophenol solvent at various concentrations [C] (g / 100 ml), and [ηsp (specific viscosity) / c] measured at 35 ° C. was extrapolated to zero for the dissolved solution. The value [η] was taken as the intrinsic viscosity.
Melting point
Using a differential scanning calorimeter Model 1090 manufactured by DuPont, the measurement was carried out at a heating rate of 20 ° C./min to determine the melting peak temperature. If this melting peak cannot be measured clearly, use a micro-melting point measuring device (manufactured by Yanagimoto Seisakusho) to insert a 3 g sample between two cover glasses and raise the temperature while holding it gently with tweezers. The temperature was raised at a rate of 20 ° C./min, and the thermal change of the polymer was observed. At this time, the temperature at which the polymer softened and began to flow (softening point) was defined as the melting point here.
Yarn collecting capacity during spinning
At the time of spinning, the raw yarn is temporarily stored in a can, transported to the next creel process, and a number of raw yarns are bundled and supplied to a stretching machine. As a comparison, the amount of raw yarn cans of other composite fibers was compared.
During stretching, thread breakage
The drawing machine was temporarily stopped during the drawing of the original yarn, the number of single yarn breaks in the drawn tow in the second hot water bath was checked, and the number of single yarn breaks in Comparative Example 2 was set to 100%. A comparison of the number of yarn breaks in fibers.
Push-in crimper ejection
The stretched tow was supplied to a press-type crimper, and after crimping, the state of discharge of the tow from the crimper box was visually determined. The case where the tow was naturally discharged from the crimper box without any problem was extremely good, and the case where the tow was not clogged and was discharged from the crimper box and did not hinder the operation but the discharge was slightly irregular was evaluated as good. A case where the tow was clogged and not discharged from the crimper box was determined to be defective.
Anti-sticking ability of yarn
The state of sticking of the yarn immediately after spinning was visually determined. When the fibers do not stick together at all, the anti-sticking ability is extremely large, and when this sticking is small but slightly present, the anti-sticking ability is large. Judged.
Interfacial adhesion strength between elastomer and polyester
Fifty heat-bondable composite fibers of the manufactured product were randomly extracted, and the state of peeling at the interface between the elastomer and the polyester in the cross section of the fiber was visually evaluated by an electron microscope. When the number of fibers having no interfacial peeling was 5 or less, the interfacial adhesive strength was high, and when the number of fibers having interfacial peeling was 30 or more, the interfacial adhesive strength was low.
Thermal adhesion between fibers
The heat-adhesive conjugate fiber is mixed with a hollow polyethylene terephthalate short fiber having a fineness of 14 denier, a fiber length of 64 mm, and a crimp number of 9 / inch obtained by a conventional method at a weight ratio of 30:70. After making a card sliver and heat-treating it at a temperature of 200 ° C for 10 minutes with a hot air circulating drier, cut the sliver to a length of 20 mm, fix both ends of the cut to a tensile tester, and speed m / min. The stress at the time of cutting was measured. The measured value when the conjugate fiber of Comparative Example 2 was used was taken as 100%, and the value compared with the case of other conjugate fibers was shown based on this value.
Crimp modulus
The crimp elastic modulus of the conjugate fiber was measured according to JIS L1074, and the value of Comparative Example 2 was set as 100% as a reference, and the value compared with the other conjugate fibers was shown.
Three-dimensional crimp expression ability
The composite fiber was opened, hung on a card, cut into webs, cut to 10 cm in length and width, heat-treated in a hot air dryer at 140 ° C for 10 minutes in a free state, and the number of crimps was measured in accordance with JIS L1074 .
Opening process
The unspread portion of the conjugate fiber when passed through the 100g opener opening step is separated and weighed, and the weight of the unspread portion of the other conjugate fiber is determined based on the weight of Comparative Example 2 as 100%. Compared.
Card cylinder winding
When the composite fiber is hung on a carding machine, the supply of the fiber is stopped during operation in a steady state, and the fiber weight when all the fibers are discharged from the carding machine after the supply is stopped is measured. The measured value of the conjugate fiber of Comparative Example 2 was set to 100%, and the value compared with other conjugate fibers was shown based on this value.
Card web spot, NEP
A composite fiber is passed through a card machine and the state of the web at the exit of the card machine is visually judged. The case where there was no web unevenness or nep was extremely good, the case where there was little web was good, and the case where there were many webs was bad.
Repellency and durability after heat treatment
The mixed cotton web at the time of measuring the above-mentioned inter-fiber thermal adhesive force is laminated, and in the form of a flat plate, at a temperature of 200 ° C., heat-treated with a heat circulating drier for 10 minutes, and the density adjusted in a flat plate shape is 0.035 g / cm.^ThreeCreate a 5cm thick fibrous structure, cross section 20cm^TwoCompressed by 1 cm with a cylindrical rod having a flat lower surface, measured its stress (initial stress), made it repulsive, and set the measured value when the composite fiber of Comparative Example 2 was used as 100%, based on this , A value compared with other composite fibers was shown.
800g / cm after this measurement^TwoAfter compressing with a load of 10 seconds, the operation was left unloaded for 5 seconds and repeated 360 times, and after 24 hours, the compressive stress was measured again.
The ratio of the change in the stress after repeated compression to the initial stress is defined as the durability of the fibrous structure, and the value when the conjugate fiber of Comparative Example 2 is used is set to 100%. The indicated values were shown.
Hardness unevenness after heat treatment
After the heat treatment described above, the surface of the fibrous structure prepared for the measurement of rebound and durability was touched with a hand, and unevenness of hardness was sensory evaluated. A case where there was no unevenness in the surface hardness was regarded as good, and a case where there were many irregularities was regarded as poor.
Example 1 and Comparative Examples 1 to 3
An acid component obtained by mixing terephthalic acid and isophthalic acid at 85/15 (mol%) is polymerized with butylene glycol, and the obtained polybutylene terephthalate 45% (weight%) is further polybutylene glycol (molecular weight 2000) 55% (% By weight) to obtain a block copolymerized polyether polyester elastomer. This thermoplastic elastomer had an intrinsic viscosity of 1.3 and a melting point of 172 ° C.
The thermoplastic elastomer and polybutylene terephthalate were combined with each other in a composite spinneret (number of holes) as shown in FIG. 3 so that the area ratio became 50/50 so that the elastomer was arranged in the crescent-shaped portion of FIG. 260 holes), and a spinning oil agent was added to give 0.05% by weight of a potassium salt of uriuryl phosphate to the fiber, and the fiber was spun to obtain a conjugate fiber of Example 1. In this comparative example, the fiber cross section is as shown in (a) to (c) of FIG. 2 so that the composite is a side-by-side type in (a) and the elastomer is a sheath component in (b). In (c), the elastomer was disposed so as to be an eccentric core-sheath type sheath component, and composite spinning was performed using a known die. These composite fibers were used as Comparative Examples 1, 2, and 3, respectively. These unstretched fibers are stretched in a two-stage warm water bath at temperatures of 60 ° C. and 90 ° C., at draw ratios of 2.5 and 1.2, and then lauryl phosphate potassium salt is applied, and then mechanically crimped with a press-type crimper. And then dried at a temperature of 60 ° C. and cut into 64 mm.
Regarding the physical properties of the obtained fiber, the thickness was 9 denier, and the adhesion rate of the oil agent was 0.2% by weight. The conjugate fiber of Example 1 had a fiber cross-sectional circumference of 35%, a curvature radius ratio Cr of 1.2, a curvature ratio C of 1.73, and a thickness ratio D of 2.1. Table 1 summarizes the properties of these composite fibers in terms of the cotton-forming conjugate fiber properties, the openability / carding properties, and the fiber structure properties.
Regarding the cotton-forming property, in Comparative Examples 2 and 3, since there is much sticking, the raw yarn collecting ability and the stretched yarn breakage are large, and the discharging property from the crimper box is poor. It was good.
Regarding the properties of the conjugate fiber, in Comparative Examples 2 and 3, the effect of preventing sticking of the original yarn was small, and a large amount of sticking fiber was generated, so that an extremely thick fiber was formed. In this case, the number of constituent fibers of the conjugate fiber is extremely small in practice, and the adhesive strength as a fiber structure is low. On the other hand, in Comparative Example 1 and Example 1, there is little sticking of the yarn and the composite fiber is dispersed relatively uniformly inside the fiber structure, so that the adhesive strength is high. Comparing Comparative Example 1 with Example 1, Example 1 showed higher adhesive strength and was better.
Regarding the crimp characteristics of the conjugate fiber, in Comparative Example 1, it is estimated that the polyester (P) component has a half-moon shape and a nearly flat cross-sectional shape, but the crimp modulus is low. This has a bad influence on the opening property and carding property in the cotton opening step as described later. Comparative Examples 2 and 3 and Example 1 show almost the same level of crimp modulus.
In Comparative Example 2, the composite fiber had no ability to exhibit three-dimensional crimping. Comparative Examples 1 and 2 and Example 1 have crimp development performance due to cross-sectional anisotropy, but Comparative Example 3 has low three-dimensional crimp development performance due to the influence of agglutination. However, Comparative Example 1 and Example 1 have a high level of three-dimensional crimp development because they have a small amount of sticking and have a cross-sectional feature. Regarding the openability and cardability, in Comparative Examples 2 and 3, since there are many sticky fibers, it is difficult to open the cotton, and the winding around the cylinder of the card machine occurs a lot, and the unevenness of the web and the NEP often occur. Not preferred. In Comparative Example 1, the crimp elastic modulus of the conjugate fiber is low, so that the fiber is in a bundle form and is difficult to spread, the card cylinder is frequently wound, and the card web has many spots and neps.
In Example 1, the amount of sticking fibers was small, the spreadability at the time of opening cotton was good, the winding of the cylinder of the card machine was small, the unevenness of the web and the nep were small, and it was good.
Regarding the fiber structure characteristics, in Comparative Examples 1, 2, and 3, as described above, the card web condition was poor, the adhesive strength was low, the resilience was low, and the hardness unevenness was large. It was a problem.
In Example 1, both the cotton-opening property and the carding property were good, the adhesive strength at the time of heat treatment was high, and the simultaneous three-dimensional crimping was more developed, so both the repulsion and the durability were good, and the hardness unevenness was small. A good fiber structure was obtained.
Example 2
A composite fiber was obtained by treating in the same manner as in Example 1 except that the spinning oil and drawing oil in Example 1 were changed from potassium lauryl phosphate to a dispersion of a polyester polyether block copolymer, and various properties were evaluated. Was done.
In this case, as the block copolymer, terephthalic acid / isophthalic acid / ethylene glycol / polyethylene glycol block copolymer (terephthalate unit: isophthalate unit = 70: 30, terephthalate unit + isophthalate unit: polyethylene glycol unit = 5) : 1, polyethylene glycol molecular weight = 2,000, average molecular weight of block copolymer = 10,000) and surfactant POE (10 mol) nonyl phenyl ether sulfate potassium salt in a ratio of 80:20, containing 10% of the active ingredient. An aqueous dispersion was used.
The results are shown in Table 2.
In Example 1, although the spinning was slightly congested at the time of spinning and consolidation, there was no consolidation, and better characteristics were obtained.
The reason why the anti-sticking effect is further improved by adding the amorphous polyetherester-based block copolymer to the conjugate fiber is presumed as follows. That is, the block copolymer is dispersed as fine particles, and is presumed to serve as a roller interposed between the fibers before or during bundle of the yarn during spinning and to reduce the friction between the fibers. You. In addition, since the block copolymer is dispersed in water as fine particles, the conjugate fiber does not show a sticking phenomenon even when heated to a high drawable temperature, and contributes to improvement in drawability. It is inferred. The results are shown in Table 2.
Examples 3 to 8
In Example 1, the same operation as in Example 1 was performed except that the polymer discharge ratio and the spinneret specifications were changed to produce heat-bondable fibers having different fiber cross-sectional shapes as shown in Table 3 below. Their properties were evaluated.
As a result, in all cases of Examples 3 to 8, if it is described in terms of cotton-forming properties, there is little sticking of the raw yarns, and the fiber-opening property and card passing property in the non-woven fabric process are good, and it is obtained by thermoforming. The obtained fiber structure had good adhesive strength between fibers, repulsion, and durability, and a good fiber structure with less unevenness in hardness was obtained.
Example 9
Using the heat-adhesive conjugate fiber used in Example 1 and the inelastic polyester-based crimped staple fiber, after mixing the conjugate fiber with 30% based on the weight of the fiber sphere and 70% of the crimped staple fiber, Then, the mixture was passed through a roller card twice to obtain a high-cotton mixed cotton.
This bulky cotton was put into a device having a blower connected with a duct and a cotton storage box, and was stirred for 30 seconds by an air flow in the blower to obtain spherical cotton. Thereafter, the spheroidized cotton is transferred into a cotton storage box, and while the spheroidized cotton is being stirred by a weak air stream having a temperature of 195 ° C., the elastic thermoplastic elastomer is melted to form the spheroidized cotton. After that, a heat-fixing point was formed inside, and then air at room temperature was sent into the cotton storage box to perform a cooling treatment to obtain a highly elastic fiber spherical body.
When this fiber spherical body was observed using a microscope, inelastic polyester-based crimped short fibers were observed on the surface of the spherical body at a probability of 70% or more. In addition, when the cushion was blown into the cushion side ground using a blower, the bubble was good without any trouble of blowing, the feel of the obtained cushion was soft and elastic, and the compression hardness retention rate was 80,000 times. 55%, much higher than 35% of cotton with silicone applied to the surface and 32% of solidified cotton-filled cushioning with segmented polymer emulsion of polyethylene terephthalate and polyethylene oxide on the surface .
The compression hardness was 2.2 kg, higher than 0.6 kg and 0.9 kg of the above-mentioned silicone cotton and emulsion surface-solidified cotton, and 2.2 kg.
Comparative Example 4
In Example 9, in place of the elastic thermoplastic elastomer, terephthalic acid and isophthalic acid were mixed at a molar ratio of 60:40 with respect to all acid components, and a dicarboxylic acid component, and ethylene glycol and diethylene glycol were completely mixed. Same as Example 9 except that a low melting polyester polymer (melting point 110 ° C., intrinsic viscosity 0.78) copolymerized with a glycol component mixed at a molar ratio of 85:15 based on the diol component was used. Was performed to obtain a fibrous spherical body.
The fibrous body obtained here was examined after 80,000 compression tests. As a result, it was found that the delamination of the fixing points was severe. Further, the retention of compression hardness for 80,000 times was extremely poor at 15%, lacking elasticity, and the texture was extremely poor.

Industrial applicability
The heat-adhesive conjugate fiber of the present invention has a crystalline E component as one component, but inevitably occurs during the production of the conjugate fiber, and impairs fiber handling properties, process characteristics, and even the original adhesion. It achieves the elimination of the sticking phenomenon and the coexistence of the interfacial adhesive strength between the polymers, the original adhesive performance and the crimp elasticity, and various cushion materials such as furniture, beds, wadding, bedding, and seat cushions It can be suitably used as a batting for quilting wear, a nonwoven fabric for sanitary materials and medical treatment, a cloth for clothing, a carpet, a raw material for vehicle interior materials and the like.
Furthermore, the fiber spherical body using the heat-adhesive conjugate fiber of the present invention as a binder is excellent in blowing properties, so that the obtained cushioning material and filling are excellent in bulkiness, high in elasticity, soft in texture, It can be suitably used as a padding material such as a cushion material having excellent compression durability and a pillow.

Claims (17)

The crystalline thermoplastic elastomer (E) and the crystalline inelastic polyester (P) having a melting point higher than that of the elastomer (E) have a circular fiber cross section of E: P = 20: 80 to 80:20. In the composite fiber arranged in the area ratio,
A thermoadhesive conjugate fiber characterized in that its cross section and surface are specified by the following requirements (1) to (5).
Requirement {circle around (1)} In the fiber cross section, the elastomer (E) is arranged in a crescent shape formed by two arcs having different radii of curvature, and a curve (r ₁ ) having a large radius of curvature is part of the outer peripheral line. Form;
{Circle around (2)} The polyester (P) is bonded to the elastomer along a curve (r ₂ ) having a smaller radius of curvature of two curves forming a crescent shape in a fiber cross section, while the curvature is The curve (r ₁ ) having a larger radius forms a part of the fiber surface in an arc shape so that the peripheral ratio R is an outer peripheral line in a range of 25 to 49%;
(However, the circumference R is defined as follows. In a circle having a radius of (r ₁ ) in FIG. 1, it is indicated by a ratio of (L ₃ ) to the entire circumference (L ₁ + L ₃ ). The circumferential ratio R is calculated by [R = {(L ₃ ) / (L ₁ + L ₃ )} × 100 (%)].
{Circle around (3)} The radius of curvature Cr, which is the ratio (r ₁ / r ₂ ) of the radius of curvature (r ₁ ) to the radius of curvature (r ₂ ), exceeds 1 and is 2 or less;
{Circle around (4)} The curvature ratio C of the curve of the radius of curvature (r ₂ ) is in the range of 1.1 to 2.5;
(However, the curvature ratio C complies with the following definition. In FIG. 1, the length of an arc (L ₂ ) having a radius of (r ₂ ), the circumference of a circle having a radius of (r ₁ ) and the arc ( L ₂ ) and the length (L) between the contact points (between P _{1 and} P ₂ ) and the length (L), and the bending ratio C is calculated by {C = (L ₂ ) / (L)}. .)
as well as,
(5) The thickness ratio of the elastomer (E) to the polyester (P) is in the range of 1.2 to 3;
(However, the thickness ratio D complies with the following definition. In FIG. 1, it passes through the center of a circle having a radius of (r ₁ ) and the center of a circle having an arc having a radius of (r ₂ ). It indicated by the ratio of the polyester length of (P) component (L _P) and elastomer component (E) of the length (L _E) in the linear direction, the meat thickness ratio D is _{{D = (L P) /} ( L _E ) Calculated by｝) The heat-adhesive conjugate fiber according to claim 1, wherein the melting point of the elastomer (E) is in the range of 100 to 220 ° C. 2. The heat-adhesive conjugate fiber according to claim 1, wherein the melting point of the polyester (P) is higher than the melting point of the elastomer by 10 ° C. or more. The elastomer (E) is a polyester elastomer, wherein the main acid component is 40 to 100 mol% terephthalic acid and 0 to 50 mol% isophthalic acid, the main glycol component is 1,4-butanediol, and the main soft segment is 3. The thermal adhesive according to claim 2, wherein the component is a poly (alkylene oxide) glycol having an average molecular weight of 400 to 5,000, a copolymerized amount in a range of 5 to 80% by weight, and an intrinsic viscosity of 0.6 to 1.7. Composite fiber. 4. The heat-adhesive conjugate fiber according to claim 3, wherein said component (P) is polybutylene terephthalate. An oil agent mainly comprising an amorphous polyetherester block copolymer is attached to the surface of the heat-adhesive conjugate fiber in a range of 0.02 to 5.0% by weight based on the weight of the fiber. Heat-adhesive conjugate fiber. The crystalline thermoplastic elastomer (E) and the crystalline inelastic polyester (P) having a melting point higher than that of the elastomer (E) have a circular fiber cross section of E: P = 20: 80 to 80:20. A conjugate fiber arranged in an area ratio, wherein the fiber is a heat-adhesive conjugate fiber whose cross section and surface are specified by the following requirements (1) to (5) based on the total fiber weight. A fibrous spherical body composed of a group of short fibers in which 5 to 49% by weight and inelastic polyester-based crimped short fibers are blended, wherein the heat-adhesive conjugate fibers or the heat-adhesive conjugate fibers are not mixed. A highly elastic fiber spherical body, wherein a flexible heat fixing point is formed in at least a part of a fiber entanglement point with an elastic polyester crimped short fiber.
Requirement {circle around (1)} In the fiber cross section, the elastomer (E) is arranged in a crescent shape formed by two arcs having different radii of curvature, and a curve (r ₁ ) having a large radius of curvature is part of the outer peripheral line. Form;
{Circle around (2)} The polyester (P) is bonded to the elastomer along a curve (r ₂ ) having a smaller radius of curvature of two curves forming a crescent shape in a fiber cross section, while the curvature is The curve (r ₁ ) having a larger radius forms a part of the fiber surface in an arc shape so that the peripheral ratio R is an outer peripheral line in a range of 25 to 49%;
(However, the circumference R is defined as follows. In a circle having a radius of (r ₁ ) in FIG. 1, it is indicated by a ratio of (L ₃ ) to the entire circumference (L ₁ + L ₃ ). The circumferential ratio R is calculated by [R = {(L ₃ ) / (L ₁ + L ₃ )} × 100 (%)].
{Circle around (3)} The radius of curvature Cr, which is the ratio (r ₁ / r ₂ ) of the radius of curvature (r ₁ ) to the radius of curvature (r ₂ ), exceeds 1 and is 2 or less;
{Circle around (4)} The curvature ratio C of the curve of the radius of curvature (r ₂ ) is in the range of 1.1 to 2.5;
(However, the curvature ratio C complies with the following definition. In FIG. 1, the length of an arc (L ₂ ) having a radius of (r ₂ ), the circumference of a circle having a radius of (r ₁ ) and the arc ( L ₂ ) and the length (L) between the contact points (between P _{1 and} P ₂ ) and the length (L), and the bending ratio C is calculated by {C = (L ₂ ) / (L)}. .)
as well as,
(5) The thickness ratio of the elastomer (E) to the polyester (P) is in the range of 1.2 to 3;
(However, the thickness ratio D complies with the following definition. In FIG. 1, it passes through the center of a circle having a radius of (r ₁ ) and the center of a circle having an arc having a radius of (r ₂ ). It indicated by the ratio of the polyester length of (P) component (L _P) and elastomer component (E) of the length (L _E) in the linear direction, the meat thickness ratio D is _{{D = (L P) /} ( L _E ) Calculated by｝) The highly elastic fiber spherical body according to claim 7, wherein the melting point of the elastomer (E) is in the range of 100 to 220 ° C. The highly elastic fiber spherical body according to claim 7, wherein the melting point of the polyester (P) is higher than the melting point of the elastomer by 10 ° C or more. The elastomer (E) is a polyester elastomer, wherein the main acid component is 40 to 100 mol% terephthalic acid and 0 to 50 mol% isophthalic acid, the main glycol component is 1,4-butanediol, and the main soft segment is 9. The high elasticity according to claim 8, wherein the component is a poly (alkylene oxide) glycol having an average molecular weight of 400 to 5,000, a copolymerization amount in a range of 5 to 80% by weight, and an intrinsic viscosity of 0.6 to 1.7. Fiber sphere. Inelastic polyester crimped short fibers, JIS bulkiness at L-1097 alone were measured according to the method of, under a load of 0.5 g / cm ² according to a 30g / cm ³ ~120g / cm ³ A highly elastic sphere according to range 7. Inelastic polyester crimped short fibers, the claims bulky alone were measured according to the method of JIS L-1097 is a 15g / cm ³ ~60g / cm ³ under a load of 10 g / cm ² 7. The highly elastic spherical body according to 7. 8. The highly elastic spherical body according to claim 7, wherein the single elastic fineness of the inelastic polyester crimped short fibers is 1 to 100 denier. 8. The highly elastic fiber spherical body according to claim 7, wherein a smoothing agent is attached to the surface of the inelastic polyester crimped short fibers. 10. The highly elastic fiber sphere according to claim 9, wherein said component (P) is polybutylene terephthalate. 8. The highly elastic fiber sphere according to claim 7, wherein a part of the group of short fibers constituting the fiber sphere protrudes as fluff on the surface of the sphere. 17. The highly elastic fiber spheroid according to claim 16, wherein the proportion of fluff projecting from the surface of the fiber spheroid is larger in the inelastic polyester-based crimped staple fiber than in the heat-adhesive conjugate fiber.

Images