JP3776026B2 - Copolyester and heat-bondable fiber - Google Patents

Description

【００１４】
【化５】

【００１５】
【発明の実施の形態】
以下、本発明について詳細に説明する。
【００１６】
本発明の共重合ポリエステルは、該ポリエステルを構成する全ジカルボン酸成分を基準として、テレフタル酸成分が５０〜９０モル％占めていることが必要である。該テレフタル酸成分が５０モル％未満であると、得られるポリマーや繊維が融着、膠着を起こしやすくなる。一方、９０モル％を越えると風合いが硬くなる他、接着性も低下する。
【００１７】
また、共重合ポリエステルを構成する全ジカルボン酸成分を基準としてイソフタル酸成分が５モル％未満であると、熱接着性が低下し好ましくない。また、５０モル％を越えると、コスト的に不利となる他、共重合ポリエステルチップ、さらには得られる熱接着性繊維の製造時における融着が起こりやすくなる。該イソフタル酸成分は７モル％以上５０モル％以下であることが好ましく１４モル％以上４５モル％以下であることがさらに好ましい。
【００１８】
さらに、本発明の共重合ポリエステルは、該共重合ポリエステルを構成する全グリコール成分を基準としてエチレングリコール成分が９０モル％以上占めていることが必要である。該エチレングリコール成分が９０モル％未満であると、コスト的に高くなり好ましくない。該エチレングリコール成分の好ましい範囲は９５モル％以上である。
【００１９】
本発明の共重合ポリエステルの固有粘度（オルトクロロフェノール溶媒中３５℃で測定）は、０．３５〜０．６０の範囲にあることが必要である。該固有粘度が０．３５より低いと、共重合ポリエステルの機械的特性が低下するので、最終的に得られる不織布等の熱接着処理製品における、融着部分の強度が不十分なものとなる。また、０．６０よりも高いと、ポリマーの流動性が低下して、熱接着性能が低下する傾向がある。該共重合ポリエステルの固有粘度は０．４０〜０．６０の範囲が好ましく、０．５０〜０．６０の範囲がさらに好ましい。
【００２０】
本発明の共重合ポリエステルはその特性を損なわない範囲、好ましくは５モル％以下の範囲でテレフタル酸成分、イソフタル酸成分、エチレングリコール成分以外の成分を共重合していても良く、例えばナフタレンジカルボン酸、オルトフタル酸、ジフェニルジカルボン酸、ジフェニルエーテルジカルボン酸、ジフェニルスルホンジカルボン酸、ベンゾフェノンジカルボン酸、フェニルインダンジカルボン酸、５−スルホキシイソフタル酸金属塩、５−スルホキシイソフタル酸ホスホニウム塩等の芳香族ジカルボン酸、アジピン酸、ヘプタン二酸、オクタン二酸、アゼライン酸、セバシン酸、ウンデカン二酸、ドデカン二酸等の脂肪族ジカルボン酸、シクロヘキサンジカルボン酸、ジクロヘキサンジメチレンジカルボン酸等の脂環式ジカルボン、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、オクタメチレングリコール、デカメチレングリコール、ネオペンチレングリコール、ジエチレングリコール、トリエチレングリコール、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等の脂肪族グリコール、シクロヘキサンジオール、シクロヘキサンジメタノール等の脂環式グリコール、ｏ−キシリレングリコール、ｍ−キシリレングリコール、ｐ−キシリレングリコール、１，４−ビス（２−ヒドロキシエトキシ）ベンゼン、１，４−ビス（２−ヒドロキシエトキシエトキシ）ベンゼン、４，４’−ビス（２−ヒドロキシエトキシ）ビフェニル、４，４’−ビス（２−ヒドロキシエトキシエトキシ）ビフェニル、２，２−ビス［４−（２−ヒドロキシエトキシ）フェニル］プロパン、２，２−ビス［４−（２−ヒドロキシエトキシエトキシ）フェニル］プロパン、１，３−ビス（２−ヒドロキシエトキシ）ベンゼン、１，３−ビス（２−ヒドロキシエトキシエトキシ）ベンゼン、１，２−ビス（２−ヒドロキシエトキシ）ベンゼン、１，２−ビス（２−ヒドロキシエトキシエトキシ）ベンゼン、４，４’−ビス（２−ヒドロキシエトキシ）ジフェニルスルホン、４，４’−ビス（２−ヒドロキシエトキシエトキシ）ジフェニルスルホン等の芳香族グリコール、ヒドロキノン、２，２−ビス（４−ヒドロキシフェニル）プロパン、レゾルシン、カテコール、ジヒドロキシナフタレン、ジヒドロキシビフェニル、ジヒドロキシジフェニルスルホン等のジフェノール類等が挙げられる。これらは１種を単独で用いても２種以上を併用してもどちらでも良い。
【００２１】
本発明で用いられる共重合ポリエステル中には、必要に応じて少量の添加剤、例えば滑剤、顔料、染料、酸化防止剤、固相重合促進剤、蛍光増白剤、帯電防止剤、抗菌剤、紫外線吸収剤、光安定剤、熱安定剤、遮光剤、艶消剤等を含んでいてもよい。
【００２２】
本発明の共重合ポリエステルは下記一般式（Ｉ）で表されるチタン化合物と下記一般式（ＩＩ）で表されるリン化合物とをチタン元素のモル数に対するリン元素のモル数（Ｐ／Ｔｉ）が１〜４となる範囲の組成で反応せしめたチタン／リン反応物を用いて重合されている必要がある。
【００２３】
【化６】

【００２４】
【化７】

【００２５】
ここでチタン元素のモル数に対するリン元素のモル数（Ｐ／Ｔｉ）が１より小さい場合、得られるポリエステルの色調が、不良になり、かつその耐熱性が低下することがあり好ましくなく、４より大きい場合、ポリエステル生成反応に対する触媒活性が不十分になり好ましくない。チタン元素のモル数に対するリン元素のモル数（Ｐ／Ｔｉ）は１．２〜３．５の範囲が好ましく、１．５〜３．０の範囲がさらに好ましい。
【００２６】
また、チタン化合物成分（Ｉ）とリン化合物成分（ＩＩ）との触媒調製は、エチレングリコール中で加熱反応されている必要があるが、反応方法としては例えばリン化合物（ＩＩ）からなる成分とエチレングリコールとを混合して、リン化合物成分の一部又は全部を溶媒中に溶解し、この混合液にチタン化合物成分（Ｉ）を滴下し、反応系を０℃〜２００℃の温度に３０分間以上、好ましくは６０〜１５０℃の温度に４０〜９０分間、加熱することによって行われる。この反応において、反応圧力については格別の制限はなく、通常常圧下で行われる。
【００２７】
ここで上記式（Ｉ）で表されるチタン化合物としては例えば、チタンテトラブトキシド、チタンテトライソプロポキシド、チタンテトラプロポキシド、チタンテトラエトキシドなどのチタンテトラアルコキシドや、オクタアルキルトリチタネート、ヘキサアルキルジチタネート、アルキルチタネート、酢酸チタン等を挙げることができる。
【００２８】
また上記式（ＩＩ）で表されるリン化合物には該当しないが、式中のｐが０の場合は、例えば、フェニルホスホン酸、メチルホスホン酸、エチルホスホン酸、プロピルホスホン酸、イソプロピルホスホン酸、ブチルホスホン酸、トリルホスホン酸、キシリルホスホン酸、ビフェニルホスホン酸、ナフチルホスホン酸、アントリルホスホン酸、２−カルボキシフェニルホスホン酸、３−カルボキシフェニルホスホン酸、４−カルボキシフェニルホスホン酸、２，３−ジカルボキシフェニルホスホン酸、２，４−ジカルボキシフェニルホスホン酸、２，５−ジカルボキシフェニルホスホン酸、２，６−ジカルボキシフェニルホスホン酸、３，４−ジカルボキシフェニルホスホン酸、３，５−ジカルボキシフェニルホスホン酸、２，３，４−トリカルボキシフェニルホスホン酸、２，３，５−トリカルボキシフェニルホスホン酸、２，３，６−トリカルボキシフェニルホスホン酸、２，４，５−トリカルボキシフェニルホスホン酸、２，４，６−トリカルボキシフェニルホスホン酸等を挙げることができる。
【００２９】
一方、上記式（ＩＩ）中のｐが１の場合は例えば、モノメチルホスフェート、モノエチルホスフェート、モノトリメチルホスフェート、モノ−ｎ−ブチルホスフェート、モノヘキシルホスフェート、モノヘプチルホスフェート、モノノニルホスフェート、モノデシルホスフェート、モノドデシルホスフェート、モノフェニルホスフェート、モノベンジルホスフェート、モノ（４−ドデシル）フェニルホスフェート、モノ（４−メチルフェニル）ホスフェート、モノ（４−エチルフェニル）ホスフェート、モノ（４−プロピルフェニル）ホスフェート、モノ（４−ドデシルフェニル）ホスフェート、モノトリルホスフェート、モノキシリルホスフェート、モノビフェニルホスフェート、モノナフチルホスフェート、モノアントリルホスフェート等が挙げられる。
【００３０】
上記式（１）で表されるチタン化合物は予め下記式（ＩＩＩ）の多価カルボン酸及び／又はその無水物と反応させて使用する方法も好ましく用いられる。その場合、チタン化合物と多価カルボン酸及び／又はその無水物の反応モル比は（２：１）〜（２：５）の範囲が好ましい。特に好ましい範囲は（１：１）〜（１：２）である。
【００３１】
【化８】

【００３２】
本発明の共重合ポリエステルに含まれるチタン元素量は全ジカルボン酸成分に対し２〜４０ミリモル％の範囲にあるようにすることが好ましい。チタン元素量が２ミリモル％未満の場合は重合反応が遅くなり、４０ミリモル％を超える場合は得られるポリエステルの色調が、不良になり、かつその耐熱性が低下することがあり好ましくない。チタン元素量は５〜３５ミリモル％の範囲が好ましく、１０〜３０ミリモル％の範囲がさらに好ましい。
【００３３】
本発明の熱接着性繊維は、ポリエチレンテレフタレート系ポリエステル、ポリブチレンテレフタレート系ポリエステルあるいはポリトリメチレンテレフタレート系ポリエステルからなる群から選ばれた少なくとも一種のポリエステルと上記共重合ポリエステルとからなる複合繊維であることが好ましい。
【００３４】
ここで、ポリエチレンテレフタレート系ポリエステルとは、該ポリエステルの全繰り返し単位を基準として、エチレンテレフタレート繰り返し単位が９０モル％以上、好ましくは９５モル％以上、ポリトリメチレンテレフタレート系ポリエステルとは、該ポリエステルの全繰り返し単位を基準として、トリメチレンテレフタレート繰り返し単位が９０モル％以上、好ましくは９５モル％以上、ポリブチレンテレフタレート系ポリエステルとは、該ポリエステルの全繰り返し単位を基準として、ブチレンテレフタレート繰り返し単位が、９０モル％以上、好ましくは９５モル％以上を占めるポリエステルを夫々いう。これらポリエステル中にはそのポリエステル自身の特性を損なわない範囲で別の共重合成分が共重合されていても良い。
【００３５】
本発明の熱接着性繊維に使用するポリエチレンテレフタレート系ポリエステル、ポリトリメチレンテレフタレート系ポリエステル、ポリブチレンテレフタレート系ポリエステルについてもチタン触媒で重合されていることが好ましく、特にポリエチレンテレフタレート系ポリエステルについては、上述した本発明の熱接着繊維用ポリエステルに使用されるチタン化合物を用いて製造することが好ましい。
【００３６】
本発明の熱接着性繊維に使用するポリエチレンテレフタレート系ポリエステル、ポリトリメチレンテレフタレート系ポリエステル、ポリブチレンテレフタレート系ポリエステルの固有粘度は通常繊維やフィルム、ボトル等の成形品に使用される０．５０〜１．００のものが用いられる。
【００３７】
本発明の熱接着性繊維において、接着成分として配される共重合ポリエステルは、少なくとも該複合繊維表面に露出する必要があり、該表面の４０％以上を占めているように露出していることが好ましい。共重合ポリエテルが複合繊維表面に露出していない場合には、接着効果が得られないので不適当である。なお、複合繊維の任意の横断面における共重合ポリエステルの面積率は、好ましくは１０〜７０％、より好ましくは３０〜７０％、特に好ましくは３０〜５０％である。
【００３８】
このような複合形態を持つ複合繊維としては、芯鞘型複合繊維、偏芯芯鞘型複合繊維、サイドバイサイド型複合繊維等の形態を採り得ることができる。芯鞘型複合繊維の場合、共重合ポリエステルを鞘成分として配し、ポリエチレンテレフタレート系ポリエステル、ポリブチレンテレフタレート系ポリエステル、あるいはポリトリメチレンテレフタレート系ポリエステルのいずれかを芯成分として配した芯鞘型複合繊維が特に好ましい。また、芯鞘型複合繊維の場合で共重合ポリエステルを芯成分に用いる場合は、偏芯型とし該芯成分が繊維表面に少なくとも露出するように配する必要がある。さらに、サイドバイサイド型複合繊維としても好ましく使用することが出来る。
【００３９】
本発明の熱接着性繊維は、この熱接着性繊維のみの集合体とした後、不織布となしてもよいが、通常は、該熱接着性繊維を１０重量％以上含む他繊維との混合繊維集合体とした後、不織布として用いられる。
【００４０】
本発明の熱接着性繊維は、ポリエステル繊維を熱接着させて不織布を製造する際に使用するのに適しているが、その他の熱接着用途、例えば、クッション材料、詰め綿等にも広く用いることができる。
【００４１】
【実施例】
以下、実施例を挙げてさらに具体的に説明するが、本発明はこれに限定されるものではない。なお実施例中の部は重量部を示す。また各種特性は下記の方法により評価した。
（１）固有粘度：
オルトクロルフェノールを溶媒として３５℃で測定し、その相対粘度から常法により求めた。
（２）色調（Ｌ値及びｂ値）：
ポリマー試料を２９０℃、真空下で１０分間溶融し、これをアルミニウム板上で厚さ３．０±１．０ｍｍのプレートに成形後ただちに氷水中で急冷し、該プレートを１６０℃、１時間乾燥結晶化処理後、色差計調整用の白色標準プレート上に置き、プレート表面のハンターＬ値及びｂ値を、ミノルタ社製ハンター型色差計ＣＲ−２００を用いて測定した。Ｌ値は明度を示し、その数値が大きいほど明度が高いことを示し、ｂ値はその値が大きいほど黄着色の度合いが大きいことを示す。
（３）金属元素含有量：
リガク社製蛍光Ｘ線測定装置３２７０を用いて測定した。
（４）接着強度：
ＪＩＳ Ｌ１０９６記載の方法に準拠して、つかみ間隔１０ｃｍ、伸長速度２０ｃｍ／分にて引張破断力を測定した。接着強度は、引張破断力を試験片重量で除した値とした。
【００４２】
［参考例１］
エチレングリコール１３１重量部中にフェニルホスホン酸３．６重量部を１２０℃に１０分間加熱して溶解した。このエチレングリコール溶液１３４．５重量部に、さらにエチレングリコール４０重量部を加えた後、これにチタンテトラブトキシド３．８重量部を溶解させた。得られた反応系を１２０℃で６０分間撹拌し、チタン化合物とフェニルホスホン酸とを反応させ、反応生成物を含む触媒の白色スラリーを得た。この触媒スラリーのチタン含量は０．３重量％であった。
【００４３】
［参考例２］
エチレングリコール２．５重量部に無水トリメリット酸０．８重量部を溶解し、この溶液にチタンテトラブトキシド０．７重量部（無水トリメリット酸のモル量を基準として０．５モル％）を滴下し、この反応系を空気中、常圧下、８０℃に６０分間保持してチタンテトラブトキシドと無水トリメリット酸とを反応させ、反応生成物を熟成させた。その後反応系を常温に冷却し、これにアセトン１５重量部を加え、析出物をＮｏ．５ろ紙で濾過し、採取し、これを１００℃の温度で２時間乾燥した。得られた反応生成物のチタン含有量は１１．２重量％であった。
【００４４】
次に、エチレングリコール１３１重量部中にフェニルホスホン酸３．６重量部を１２０℃に１０分間加熱して溶解した。このエチレングリコール溶液１３４．５重量部に、さらにエチレングリコール４０重量部を加えた後、これに上記チタン化合物５．０重量部を溶解させた。得られた反応系を１２０℃で６０分間撹拌し、チタン化合物とフェニルホスホン酸とを反応させ、反応生成物を含む触媒の白色スラリーを得た。この触媒スラリーのチタン含量は０．３重量％であった。
【００４５】
［参考例３］
エチレングリコール１３１重量部中にモノ−ｎ−ブチルホスフェート３．５重量部を１２０℃に１０分間加熱して溶解した。このエチレングリコール溶液１３４．５重量部に、さらにエチレングリコール４０重量部を加えた後、これにチタンテトラブトキシド３．８重量部を溶解させた。得られた反応系を１２０℃で６０分間撹拌し、チタン化合物とモノ−ｎ−ブチルホスフェートとを反応させ、反応生成物を含む触媒の白色スラリーを得た。この触媒スラリーのチタン含量は０．３重量％であった。
【００４６】
［参考例４］
エチレングリコール２．５重量部に無水トリメリット酸０．８重量部を溶解し、この溶液にチタンテトラブトキシド０．７重量部（後記ポリエステルの製造に用いられる無水トリメリット酸のモル量を基準として０．５モル％）を滴下し、この反応系を空気中、常圧下、８０℃に６０分間保持してチタンテトラブトキシドと無水トリメリット酸とを反応させ、反応生成物を熟成させた。その後反応系を常温に冷却し、これにアセトン１５重量部を加え、析出物をＮｏ．５ろ紙で濾過し、採取し、これを１００℃の温度で２時間乾燥した。得られた反応生成物のチタン含有量は１１．２重量％であった。
【００４７】
次に、エチレングリコール１３１重量部中にモノ−ｎ−ブチルホスフェート３．５重量部を１２０℃に１０分間加熱して溶解した。このエチレングリコール溶液１３４．５重量部に、さらにエチレングリコール４０重量部を加えた後、これに上記チタン化合物５．０重量部を溶解させた。得られた反応系を１２０℃で６０分間撹拌し、チタン化合物とモノ−ｎ−ブチルホスフェートとを反応させ、反応生成物を含む触媒の白色スラリーを得た。この触媒スラリーのチタン含量は０．３重量％であった。
【００４８】
［参考例５］
テレフタル酸６０部、イソフタル酸４０部、エチレングリコール４５部を２４０℃においてエステル化反応させ、次いで得られた反応生成物を精留塔付き重縮合用フラスコへ入れ、２０％の酸化チタンエチレングリコールスラリーを１．７部、重縮合触媒として参考例１で製造したスラリー１．９２重量部（テレフタル酸とイソフタル酸との合計量を基準として、チタン原子量換算で２０ミリモル％）及び整色剤としてテラゾールブルー０．０００１重量部を加え、得られた反応系を温度２８５℃、３０Ｐａの高真空下で重縮合反応を行い、常法に従いチップ化した。得られたポリマーの固有粘度は０．５７０であった。結果を表１に示す。
【００４９】
［参考例６、実施例１〜２、比較例１］
参考例５において、触媒を表１記載のとおりに変更したこと以外は参考例５と同様に行った。
【００５０】
［参考例７］
参考例５において、イソフタル酸を用いることなく、テレフタル酸を１００部使用したこと以外は同様の操作を行って、固有粘度０．６２のポリエチレンテレフタレートを得た。
【００５１】
［実施例３］
参考例５の操作で得られた共重合ポリエステルを鞘成分とし、参考例７で製造したポリエチレンテレフタレートを芯成分として、鞘／芯＝５０／５０（重量比）で芯鞘型複合紡糸口金から溶融吐出し、８００ｍ／分の速度で引き取った。この際、鞘成分の溶融温度は２４０℃、芯成分の溶融温度は２８０℃とした。
【００５２】
得られた未延伸糸を延伸温度６０℃、延伸倍率３．０倍で延伸し、さらに捲縮率１０％の捲縮を与えた。次いで、得られた捲縮糸条を５１ｍｍの長さに切断して、５ｄｔｅｘの熱接着性繊維を得た。
【００５３】
繊維の横断面における共重合ポリエステルの面積率は、５０％であり、紡糸、延伸中に繊維間の膠着はなく、安定に製造することができた。
【００５４】
この熱接着性繊維２０重量部と、カット長５１ｍｍのポリエチレンテレフタレート短繊維８０重量部とを混綿し、１３０℃で接着熱処理して、不織布を得た。不織布製造中に熱接着性繊維が装置に粘着することはなく、工程性は良好であった。また、得られた不織布の接着強度は１９５Ｎ／ｇであった。
【００５５】
［実施例４］
鞘の熱接着性ポリエステルを実施例４で得られたポリエステルにしたこと以外は実施例３と同様に行った。不織布製造中に熱接着性繊維が装置に粘着することはなく、工程性は良好であった。また、得られた不織布の接着強度は２００Ｎ／ｇであった。
【００５６】
［実施例５］
芯のポリエステルをポリブチレンテレフタレートにしたこと以外は実施例３と同様に行った。不織布製造中に熱接着性繊維が装置に粘着することはなく、工程性は良好であった。また、得られた不織布の接着強度は１６５Ｎ／ｇであった。
【００５７】
［実施例６］
芯のポリエステルをポリトリメチレンテレフタレートにしたこと以外は実施例３と同様に行った。不織布製造中に熱接着性繊維が装置に粘着することはなく、工程性は良好であった。また、得られた不織布の接着強度は１８０Ｎ／ｇであった。
【００５８】
【表１】

【００５９】
【発明の効果】
本発明の共重合ポリエステルは色相が良好で、得られた繊維はポリエチレンテレフタレートをはじめとするポリエステル繊維に対する低温での熱接着性能が優れていると同時に、得られる不織布の風合いにも優れ幅広い不織布用途に有用に用いることが出来る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copolymerized polyester and a heat-adhesive fiber, and more particularly to a copolymerized polyester and a heat-adhesive fiber excellent in color tone obtained using a catalyst for producing a polyester containing a specific titanium compound and a phosphorus compound.
[0002]
[Prior art]
In recent years, in the use of non-woven fabrics, as the proportion of polyester fibers used as the constituent fibers has increased, a heat-adhesive fiber comprising a polyester-based polymer having a good heat-adhesion property with the polyester fiber as a heat-adhesive component Has come to be desired.
[0003]
Furthermore, in the production of non-woven fabrics and the like, from the viewpoint of production efficiency and energy saving, a method of bonding by heat treatment at a relatively low temperature of 100 to 150 ° C. and in a short time is often used, so that the adhesion is particularly good at a low temperature. New polyester-based heat-bondable fibers are desired.
[0004]
It is well known that when such a polyester polymer is polymerized, the reaction rate and the quality of the resulting polyester are greatly affected by the type of catalyst used in the polycondensation reaction stage. As a polycondensation catalyst of polyethylene terephthalate, an antimony compound is most widely used because it has excellent polycondensation catalyst performance and a polyester having a good color tone can be obtained.
[0005]
However, when an antimony compound is used as a polycondensation catalyst, if the polyester is continuously melt-spun for a long time, foreign matter (hereinafter, sometimes referred to simply as a base foreign matter) is deposited and deposited around the mouthpiece hole. In addition to the problem that the process becomes unstable, there is a problem that the resulting fiber also has a dark hue specific to antimony, and even when the finally obtained non-woven fabric is used for food, it is a trace amount There was a problem that antimony eluted.
[0006]
Although it has been proposed to use a titanium compound such as titanium tetrabutoxide as a polycondensation catalyst other than the antimony compound, when such a titanium compound is used, the above-described molding caused by the deposition of foreign matter in the die However, there is a new problem that the obtained polyester itself is colored yellow and the heat stability of the melt is poor.
[0007]
In order to solve the above-mentioned coloring problem, it is generally performed to add a cobalt compound to polyester to suppress yellowing. Certainly, the color tone (b value) of the polyester can be improved by adding the cobalt compound, but the problem that the addition of the cobalt compound decreases the melt heat stability of the polyester and the polymer tends to decompose. There is.
[0008]
As other titanium compounds, Japanese Patent Publication No. 48-2229 discloses the use of titanium hydroxide, and Japanese Patent Publication No. 47-26597 uses α-titanic acid as a catalyst for producing polyester. ing. However, in the former method, powdering of titanium hydroxide is not easy. On the other hand, in the latter method, α-titanic acid is easily changed in quality, so its storage and handling are not easy. In addition, it is difficult to obtain a polymer having a good color tone (b value).
[0009]
JP-B-59-46258 discloses a product obtained by reacting a titanium compound with trimellitic acid, and JP-A-58-38822 discloses a reaction between a titanium compound and a phosphite. It is disclosed that each of the products obtained in this manner is used as a catalyst for producing a polyester. Certainly, according to this method, although the melt heat stability of the polyester is improved to some extent, the color tone of the obtained polymer is not sufficient, and therefore further improvement of the polymer color tone is desired.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide a heat-adhesive fiber that can provide a non-woven fabric that has excellent thermal adhesion at low temperatures to polyester fibers such as polyethylene terephthalate, and that does not contain antimony and has excellent hue. .
[0011]
[Means for Solving the Problems]
As a result of intensive studies in view of the above-described prior art to achieve the above object, the present inventor has completed the present invention.
[0012]
That is, the object of the present invention is to
In the case of obtaining a copolymerized polyester polymer by polycondensation in the presence of a catalyst using an alkylene glycol ester of terephthalic acid and its low polymer and an alkylene glycol ester of isophthalic acid and its low polymer as a polymerization starting material,
As the catalyst, a titanium compound represented by the following formula (I) and a phosphorus compound represented by the following formula (II) have a molar number of phosphorus element (P / Ti) of 1 to 4 with respect to the molar number of titanium element. Using the precipitate obtained by heating in glycol, the ethylene terephthalate unit occupies 50 to 90 mol%, based on all repeating units of the copolymer polyester, and 5 to 50 mol%. This is achieved by a method for producing a copolyester, characterized in that a copolyester having an ethylene isophthalate unit and an intrinsic viscosity in the range of 0.35 to 0.60 is obtained.
[0013]
[Formula 4]

[0014]
[Chemical formula 5]

[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0016]
In the copolymerized polyester of the present invention, it is necessary that the terephthalic acid component occupies 50 to 90 mol% based on all dicarboxylic acid components constituting the polyester. When the terephthalic acid component is less than 50 mol%, the resulting polymer or fiber is likely to be fused or glued. On the other hand, if it exceeds 90 mol%, the texture becomes hard and the adhesiveness also decreases.
[0017]
Further, if the isophthalic acid component is less than 5 mol% based on the total dicarboxylic acid component constituting the copolymer polyester, the thermal adhesiveness is undesirably lowered. On the other hand, if it exceeds 50 mol%, it becomes disadvantageous in terms of cost, and fusion during the production of the copolyester chip and the resulting heat-bondable fiber tends to occur. The isophthalic acid component is preferably 7 mol% or more and 50 mol% or less, more preferably 14 mol% or more and 45 mol% or less.
[0018]
Furthermore, it is necessary that the copolymerized polyester of the present invention occupies 90 mol% or more of the ethylene glycol component based on the total glycol components constituting the copolymerized polyester. If the ethylene glycol component is less than 90 mol%, the cost increases, which is not preferable. A preferable range of the ethylene glycol component is 95 mol% or more.
[0019]
The intrinsic viscosity of the copolymerized polyester of the present invention (measured in an orthochlorophenol solvent at 35 ° C.) needs to be in the range of 0.35 to 0.60. When the intrinsic viscosity is lower than 0.35, the mechanical properties of the copolyester are deteriorated, so that the strength of the fused portion in the final heat-bonded product such as a nonwoven fabric is insufficient. Moreover, when higher than 0.60, there exists a tendency for the fluidity | liquidity of a polymer to fall and for heat bonding performance to fall. The intrinsic viscosity of the copolyester is preferably in the range of 0.40 to 0.60, and more preferably in the range of 0.50 to 0.60.
[0020]
The copolymerized polyester of the present invention may be copolymerized with a component other than the terephthalic acid component, isophthalic acid component, and ethylene glycol component within a range that does not impair the properties thereof, preferably within a range of 5 mol% or less. For example, naphthalenedicarboxylic acid Aromatic dicarboxylic acids such as orthophthalic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, benzophenone dicarboxylic acid, phenylindane dicarboxylic acid, metal salt of 5-sulfoxyisophthalic acid, phosphonium salt of 5-sulfoxyisophthalic acid, Alicyclic dicarbohydrates such as aliphatic dicarboxylic acids such as adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, cyclohexanedicarboxylic acid, dichlorohexanedimethylenedicarboxylic acid, etc. , Trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol and other aliphatic glycols, cyclohexane Diol, cycloaliphatic glycol such as cyclohexanedimethanol, o-xylylene glycol, m-xylylene glycol, p-xylylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, 1,4-bis (2 -Hydroxyethoxyethoxy) benzene, 4,4'-bis (2-hydroxyethoxy) biphenyl, 4,4'-bis (2-hydroxyethoxyethoxy) biphenyl, 2 , 2-bis [4- (2-hydroxyethoxy) phenyl] propane, 2,2-bis [4- (2-hydroxyethoxyethoxy) phenyl] propane, 1,3-bis (2-hydroxyethoxy) benzene, , 3-bis (2-hydroxyethoxyethoxy) benzene, 1,2-bis (2-hydroxyethoxy) benzene, 1,2-bis (2-hydroxyethoxyethoxy) benzene, 4,4′-bis (2-hydroxy) Ethoxy) diphenylsulfone, aromatic glycols such as 4,4′-bis (2-hydroxyethoxyethoxy) diphenylsulfone, hydroquinone, 2,2-bis (4-hydroxyphenyl) propane, resorcin, catechol, dihydroxynaphthalene, dihydroxybiphenyl Dipheno such as dihydroxydiphenylsulfone Kind, and the like. These may be used alone or in combination of two or more.
[0021]
In the copolymerized polyester used in the present invention, a small amount of additives as necessary, such as lubricants, pigments, dyes, antioxidants, solid phase polymerization accelerators, fluorescent brighteners, antistatic agents, antibacterial agents, An ultraviolet absorber, a light stabilizer, a heat stabilizer, a light-shielding agent, a matting agent, and the like may be included.
[0022]
The copolyester of the present invention comprises a titanium compound represented by the following general formula (I) and a phosphorus compound represented by the following general formula (II) in the number of moles of phosphorus element relative to the number of moles of titanium element (P / Ti). Must be polymerized using a titanium / phosphorus reactant reacted with a composition in the range of 1 to 4.
[0023]
[Chemical 6]

[0024]
[Chemical 7]

[0025]
Here, if the number of moles of phosphorus element relative to the number of moles of titanium element (P / Ti) is less than 1, the resulting polyester may be unsatisfactory in color tone, and its heat resistance may be lowered. If it is large, the catalyst activity for the polyester formation reaction becomes insufficient, which is not preferable. The number of moles of phosphorus element (P / Ti) relative to the number of moles of titanium element is preferably in the range of 1.2 to 3.5, and more preferably in the range of 1.5 to 3.0.
[0026]
Further, the catalyst preparation of the titanium compound component (I) and the phosphorus compound component (II) needs to be heated and reacted in ethylene glycol. As a reaction method, for example, a component comprising the phosphorus compound (II) and ethylene Glycol is mixed, part or all of the phosphorus compound component is dissolved in a solvent, the titanium compound component (I) is dropped into this mixed solution, and the reaction system is heated to a temperature of 0 ° C. to 200 ° C. for 30 minutes or more. , Preferably by heating to a temperature of 60 to 150 ° C. for 40 to 90 minutes. In this reaction, the reaction pressure is not particularly limited and is usually carried out under normal pressure.
[0027]
Examples of the titanium compound represented by the above formula (I) include titanium tetraalkoxides such as titanium tetrabutoxide, titanium tetraisopropoxide, titanium tetrapropoxide, titanium tetraethoxide, octaalkyltrititanate, and hexaalkyl. Examples include dititanate, alkyl titanate, and titanium acetate.
[0028]
Although not applicable to the phosphorus compound represented by the above formula (II), when p in the formula is 0, for example, phenylphosphonic acid, methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, isopropylphosphonic acid, butyl Phosphonic acid, tolylphosphonic acid, xylylphosphonic acid, biphenylphosphonic acid, naphthylphosphonic acid, anthrylphosphonic acid, 2-carboxyphenylphosphonic acid, 3-carboxyphenylphosphonic acid, 4-carboxyphenylphosphonic acid, 2,3- Dicarboxyphenylphosphonic acid, 2,4-dicarboxyphenylphosphonic acid, 2,5-dicarboxyphenylphosphonic acid, 2,6-dicarboxyphenylphosphonic acid, 3,4-dicarboxyphenylphosphonic acid, 3,5- Dicarboxyphenylphosphonic acid, 2,3,4-trica Boxyphenylphosphonic acid, 2,3,5-tricarboxyphenylphosphonic acid, 2,3,6-tricarboxyphenylphosphonic acid, 2,4,5-tricarboxyphenylphosphonic acid, 2,4,6-tricarboxy Ru can be exemplified such as phenylphosphonic acid.
[0029]
On the other hand, when p in the formula (II) is 1, for example, monomethyl phosphate, monoethyl phosphate, monotrimethyl phosphate, mono-n-butyl phosphate, monohexyl phosphate, monoheptyl phosphate, monononyl phosphate, monodecyl phosphate , Monododecyl phosphate, monophenyl phosphate, monobenzyl phosphate, mono (4-dodecyl) phenyl phosphate, mono (4-methylphenyl) phosphate, mono (4-ethylphenyl) phosphate, mono (4-propylphenyl) phosphate, mono (4-dodecylphenyl) phosphate, monotolyl phosphate, monoxylyl phosphate, monobiphenyl phosphate, mononaphthyl phosphate, monoanthryl phosphate And the like.
[0030]
A method in which the titanium compound represented by the above formula (1) is reacted with a polyvalent carboxylic acid of the following formula (III) and / or an anhydride thereof is also preferably used. In that case, the reaction molar ratio of the titanium compound and the polyvalent carboxylic acid and / or anhydride thereof is preferably in the range of (2: 1) to (2: 5). A particularly preferable range is (1: 1) to (1: 2).
[0031]
[Chemical 8]

[0032]
The amount of titanium element contained in the copolymerized polyester of the present invention is preferably in the range of 2 to 40 mmol% with respect to the total dicarboxylic acid component. When the amount of elemental titanium is less than 2 mmol%, the polymerization reaction is slow, and when it exceeds 40 mmol%, the color tone of the resulting polyester is unsatisfactory and its heat resistance is lowered. The amount of titanium element is preferably in the range of 5 to 35 mmol%, more preferably in the range of 10 to 30 mmol%.
[0033]
The heat-adhesive fiber of the present invention is a composite fiber comprising at least one polyester selected from the group consisting of polyethylene terephthalate polyester, polybutylene terephthalate polyester or polytrimethylene terephthalate polyester and the above copolyester. Is preferred.
[0034]
Here, the polyethylene terephthalate polyester is based on all the repeating units of the polyester, the ethylene terephthalate repeating unit is 90 mol% or more, preferably 95 mol% or more, and the polytrimethylene terephthalate polyester is the entire polyester. Based on the repeating unit, the trimethylene terephthalate repeating unit is 90 mol% or more, preferably 95 mol% or more. The polybutylene terephthalate-based polyester is 90 mol of the butylene terephthalate repeating unit based on all repeating units of the polyester. % Or more, preferably 95% or more of the polyester. In these polyesters, another copolymer component may be copolymerized as long as the properties of the polyester itself are not impaired.
[0035]
The polyethylene terephthalate-based polyester, polytrimethylene terephthalate-based polyester, and polybutylene terephthalate-based polyester used for the heat-bondable fiber of the present invention are also preferably polymerized with a titanium catalyst, and the polyethylene terephthalate-based polyester is particularly described above. It is preferable to manufacture using the titanium compound used for the polyester for thermal bonding fibers of the present invention.
[0036]
The intrinsic viscosity of the polyethylene terephthalate-based polyester, polytrimethylene terephthalate-based polyester, and polybutylene terephthalate-based polyester used in the heat-bondable fiber of the present invention is usually 0.50 to 1 used for molded products such as fibers, films, and bottles. .00 is used.
[0037]
In the heat-adhesive fiber of the present invention, the copolyester arranged as an adhesive component needs to be exposed at least on the surface of the composite fiber, and may be exposed so as to occupy 40% or more of the surface. preferable. If the copolymerized polyether is not exposed on the surface of the composite fiber, it is not suitable because an adhesive effect cannot be obtained. In addition, the area ratio of the copolyester in an arbitrary cross section of the composite fiber is preferably 10 to 70%, more preferably 30 to 70%, and particularly preferably 30 to 50%.
[0038]
As the composite fiber having such a composite form, forms such as a core-sheath composite fiber, an eccentric core-sheath composite fiber, and a side-by-side composite fiber can be taken. In the case of a core-sheath type composite fiber, a copolymer polyester is arranged as a sheath component, and a core-sheath type composite fiber in which any one of polyethylene terephthalate polyester, polybutylene terephthalate polyester, or polytrimethylene terephthalate polyester is arranged as a core component Is particularly preferred. In the case of the core-sheath type composite fiber, when the copolymer polyester is used as the core component, it is necessary to use an eccentric type so that the core component is exposed at least on the fiber surface. Furthermore, it can be preferably used as a side-by-side type composite fiber.
[0039]
The heat-adhesive fiber of the present invention may be a non-woven fabric after the aggregate of only the heat-adhesive fibers, but is usually a mixed fiber with other fibers containing 10% by weight or more of the heat-adhesive fibers. After forming an aggregate, it is used as a nonwoven fabric.
[0040]
The heat-adhesive fiber of the present invention is suitable for use in producing a nonwoven fabric by heat-bonding polyester fibers, but is also widely used in other heat-adhesive applications, such as cushioning materials and stuffed cotton. Can do.
[0041]
【Example】
Hereinafter, although an example is given and it explains still more concretely, the present invention is not limited to this. In addition, the part in an Example shows a weight part. Various characteristics were evaluated by the following methods.
(1) Intrinsic viscosity:
It was measured at 35 ° C. using orthochlorophenol as a solvent, and determined from the relative viscosity by a conventional method.
(2) Color tone (L value and b value):
A polymer sample was melted at 290 ° C. under vacuum for 10 minutes, formed into a plate having a thickness of 3.0 ± 1.0 mm on an aluminum plate, and immediately cooled in ice water. The plate was dried at 160 ° C. for 1 hour. After the crystallization treatment, the plate was placed on a white standard plate for color difference adjustment, and the Hunter L value and b value on the plate surface were measured using a Hunter type color difference meter CR-200 manufactured by Minolta. The L value indicates the lightness, and the larger the value, the higher the lightness, and the b value the greater the value, the greater the degree of yellowing.
(3) Metal element content:
Measurement was performed using a fluorescent X-ray measurement apparatus 3270 manufactured by Rigaku Corporation.
(4) Adhesive strength:
Based on the method described in JIS L1096, the tensile breaking force was measured at a gripping interval of 10 cm and an elongation rate of 20 cm / min. The adhesive strength was a value obtained by dividing the tensile breaking force by the weight of the test piece.
[0042]
[Reference Example 1]
3.6 parts by weight of phenylphosphonic acid was dissolved in 131 parts by weight of ethylene glycol by heating at 120 ° C. for 10 minutes. After further adding 40 parts by weight of ethylene glycol to 134.5 parts by weight of this ethylene glycol solution, 3.8 parts by weight of titanium tetrabutoxide was dissolved therein. The resulting reaction system was stirred at 120 ° C. for 60 minutes to allow the titanium compound and phenylphosphonic acid to react to obtain a white slurry of catalyst containing the reaction product. The titanium content of this catalyst slurry was 0.3% by weight.
[0043]
[Reference Example 2]
0.8 parts by weight of trimellitic anhydride is dissolved in 2.5 parts by weight of ethylene glycol, and 0.7 parts by weight of titanium tetrabutoxide (0.5 mol% based on the molar amount of trimellitic anhydride) is added to this solution. The reaction system was dropped and kept at 80 ° C. for 60 minutes in air at normal pressure to react titanium tetrabutoxide with trimellitic anhydride, thereby aging the reaction product. Thereafter, the reaction system was cooled to room temperature, and 15 parts by weight of acetone was added thereto. It was filtered through 5 filter paper, collected, and dried at a temperature of 100 ° C. for 2 hours. The titanium content of the obtained reaction product was 11.2% by weight.
[0044]
Next, 3.6 parts by weight of phenylphosphonic acid was dissolved in 131 parts by weight of ethylene glycol by heating at 120 ° C. for 10 minutes. After further adding 40 parts by weight of ethylene glycol to 134.5 parts by weight of this ethylene glycol solution, 5.0 parts by weight of the titanium compound was dissolved therein. The resulting reaction system was stirred at 120 ° C. for 60 minutes to allow the titanium compound and phenylphosphonic acid to react to obtain a white slurry of catalyst containing the reaction product. The titanium content of this catalyst slurry was 0.3% by weight.
[0045]
[Reference Example 3]
3.5 parts by weight of mono-n-butyl phosphate was dissolved in 131 parts by weight of ethylene glycol by heating at 120 ° C. for 10 minutes. After further adding 40 parts by weight of ethylene glycol to 134.5 parts by weight of this ethylene glycol solution, 3.8 parts by weight of titanium tetrabutoxide was dissolved therein. The resulting reaction system was stirred at 120 ° C. for 60 minutes to react the titanium compound with mono-n-butyl phosphate to obtain a white slurry of catalyst containing the reaction product. The titanium content of this catalyst slurry was 0.3% by weight.
[0046]
[Reference Example 4]
0.8 parts by weight of trimellitic anhydride is dissolved in 2.5 parts by weight of ethylene glycol, and 0.7 parts by weight of titanium tetrabutoxide (based on the molar amount of trimellitic anhydride used in the production of polyester described later) is dissolved in this solution. 0.5 mol%) was added dropwise, and the reaction system was kept at 80 ° C. for 60 minutes in air under normal pressure to react titanium tetrabutoxide with trimellitic anhydride to age the reaction product. Thereafter, the reaction system was cooled to room temperature, and 15 parts by weight of acetone was added thereto. It was filtered through 5 filter paper, collected, and dried at a temperature of 100 ° C. for 2 hours. The titanium content of the obtained reaction product was 11.2% by weight.
[0047]
Next, 3.5 parts by weight of mono-n-butyl phosphate was dissolved in 131 parts by weight of ethylene glycol by heating at 120 ° C. for 10 minutes. After further adding 40 parts by weight of ethylene glycol to 134.5 parts by weight of this ethylene glycol solution, 5.0 parts by weight of the titanium compound was dissolved therein. The resulting reaction system was stirred at 120 ° C. for 60 minutes to react the titanium compound with mono-n-butyl phosphate to obtain a white slurry of catalyst containing the reaction product. The titanium content of this catalyst slurry was 0.3% by weight.
[0048]
[ Reference Example 5 ]
60 parts of terephthalic acid, 40 parts of isophthalic acid, and 45 parts of ethylene glycol are esterified at 240 ° C., and the resulting reaction product is placed in a polycondensation flask equipped with a rectifying column, and 20% titanium oxide ethylene glycol slurry 1.7 parts by weight, 1.92 parts by weight of the slurry produced in Reference Example 1 as a polycondensation catalyst (20 mmol% in terms of titanium atomic weight based on the total amount of terephthalic acid and isophthalic acid) and Terra as a color adjuster 0.0001 part by weight of sol blue was added, and the resulting reaction system was subjected to a polycondensation reaction under a high vacuum at a temperature of 285 ° C. and 30 Pa to form a chip according to a conventional method. The obtained polymer had an intrinsic viscosity of 0.570. The results are shown in Table 1.
[0049]
[ Reference Example 6, Examples 1-2 , Comparative Example 1]
In Reference Example 5 , the same procedure as in Reference Example 5 was performed except that the catalyst was changed as shown in Table 1.
[0050]
[Reference Example 7 ]
In Reference Example 5 , the same operation was performed except that 100 parts of terephthalic acid was used without using isophthalic acid to obtain polyethylene terephthalate having an intrinsic viscosity of 0.62.
[0051]
[Example 3 ]
The copolymer polyester obtained by the operation of Reference Example 5 was used as the sheath component, and the polyethylene terephthalate produced in Reference Example 7 was used as the core component, and melted from the core-sheath compound spinneret at sheath / core = 50/50 (weight ratio). The liquid was discharged and taken up at a speed of 800 m / min. At this time, the melting temperature of the sheath component was 240 ° C., and the melting temperature of the core component was 280 ° C.
[0052]
The obtained undrawn yarn was drawn at a drawing temperature of 60 ° C. and a draw ratio of 3.0 times, and further crimped with a crimp rate of 10%. Subsequently, the obtained crimped yarn was cut into a length of 51 mm to obtain a heat-adhesive fiber of 5 dtex.
[0053]
The area ratio of the copolyester in the cross section of the fiber was 50%, and there was no sticking between the fibers during spinning and drawing, and the fiber could be stably produced.
[0054]
20 parts by weight of this heat-adhesive fiber and 80 parts by weight of short polyethylene terephthalate fibers having a cut length of 51 mm were mixed and subjected to adhesive heat treatment at 130 ° C. to obtain a nonwoven fabric. The heat-adhesive fiber did not stick to the apparatus during the production of the nonwoven fabric, and the processability was good. Moreover, the adhesive strength of the obtained nonwoven fabric was 195 N / g.
[0055]
[Example 4 ]
The same procedure as in Example 3 was performed except that the heat-adhesive polyester of the sheath was changed to the polyester obtained in Example 4. The heat-adhesive fiber did not stick to the apparatus during the production of the nonwoven fabric, and the processability was good. Moreover, the adhesive strength of the obtained nonwoven fabric was 200 N / g.
[0056]
[Example 5 ]
The same procedure as in Example 3 was conducted except that the core polyester was polybutylene terephthalate. The heat-adhesive fiber did not stick to the apparatus during the production of the nonwoven fabric, and the processability was good. Moreover, the adhesive strength of the obtained nonwoven fabric was 165 N / g.
[0057]
[Example 6 ]
Example 3 was repeated except that the core polyester was polytrimethylene terephthalate. The heat-adhesive fiber did not stick to the apparatus during the production of the nonwoven fabric, and the processability was good. Moreover, the adhesive strength of the obtained nonwoven fabric was 180 N / g.
[0058]
[Table 1]

[0059]
【The invention's effect】
The copolyester of the present invention has a good hue, and the obtained fibers have excellent low-temperature thermal bonding performance to polyester fibers such as polyethylene terephthalate, and at the same time, are excellent in the texture of the resulting nonwoven fabric and are used in a wide range of nonwoven fabrics. It can be used usefully.

Claims (10)

When a copolymerized polyester polymer is obtained by polycondensation in the presence of a catalyst using an alkylene glycol ester of terephthalic acid and / or its low polymer and an alkylene glycol ester of isophthalic acid and / or its low polymer as a polymerization starting material,
As the catalyst, a titanium compound represented by the following formula (I) and a phosphorus compound represented by the following formula (II) have a molar number of phosphorus element (P / Ti) of 1 to 4 with respect to the molar number of titanium element. Using the precipitate obtained by heating in glycol, the ethylene terephthalate unit occupies 50 to 90 mol%, based on the total repeating units of the copolymer polyester, and 5 to 50 mol%. To obtain a copolymer polyester having an intrinsic viscosity in the range of 0.35 to 0.60.

  The manufacturing method of the copolyester of Claim 1 using the phosphorus compound whose numerical value of p in Formula (II) is 1. The method for producing a copolyester according to claim 2 , wherein the phosphorus compound is a monoalkyl phosphate.   The method for producing a copolyester according to claim 1, wherein the titanium compound of the formula (I) uses a catalyst for producing a polyester selected from titanium tetraalkoxides, octaalkyltrititanates, and hexaalkyldititanates. The titanium compound of the formula (I) is previously reacted with a polyvalent carboxylic acid of the following general formula (III) and / or an acid anhydride thereof at a composition in the reaction molar ratio range (2: 1) to (2: 5). And then reacting with the phosphorus compound of the formula (II).

  A copolymerized polyester obtained by the method according to claim 1, wherein the content of elemental titanium is in the range of 2 to 40 mmol% with respect to the total dicarboxylic acid component. A thermoadhesive fiber in which the copolyester according to claim 6 is arranged so as to be exposed at least on its surface. The heat-adhesive fiber according to claim 7 , wherein the heat-adhesive fiber is a core-sheath type composite fiber in which polyethylene terephthalate polyester is disposed as a core component and copolymer polyester is disposed as a sheath component. The heat-adhesive fiber according to claim 7 , wherein the heat-adhesive fiber is a core-sheath type composite fiber in which a polytrimethylene terephthalate polyester is disposed as a core component and a copolymer polyester is disposed as a sheath component. The heat-bondable fiber according to claim 7 , wherein the heat-bondable fiber is a core-sheath type composite fiber in which a polybutylene terephthalate-based polyester is disposed as a core component and a copolymer polyester is disposed as a sheath component.