JP2004277916A - Polyester fiber for sewing thread and sewing thread using the polyester fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyester fiber for a sewing thread, which has an excellent color tone (color value b), causes an extremely small amount of a deposit attached to a spinneret even in long-time continuous spinning through the spinneret, has slight occurrence of breakage, etc., in a twisting process for sewing thread production, slight unevenness of fineness (evenness U%) and excellent dyeing stability and a sewing thread using the polyester fiber. <P>SOLUTION: The polyester fiber for a sewing thread is constituted of a polyester polymer. The polyester polymer is one obtained by subjecting an aromatic dicarboxylate ester to condensation polymerization in the presence of a catalyst containing a specific titanium compound component and phosphorus compound, the molar ratio of the content of phosphorus element/titanium metal element is 1-15 and the total of the contents is 10-100 millimol % per repeating unit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１８】
【化７】

【００１９】
【化８】

【００２０】
【数２】

【００２１】
【発明の実施の形態】
以下、本発明について詳細に説明する。
【００２２】
本発明の縫糸用ポリエステル繊維は、ポリエステルポリマーから構成されており、該ポリエステルポリマーはチタン化合物成分とリン化合物とを含む触媒の存在下に芳香族ジカルボキシレートエステルを重縮合して得られるポリマーである。
【００２３】
そして本発明で用いられるチタン化合物成分は、下記一般式（Ｉ）で表されるチタンアルコキシド及び下記一般式（Ｉ）で表されるチタンアルコキシドと下記一般式（ＩＩ）で表される芳香族多価カルボン酸又はその無水物とを反応させた生成物からなる群から選ばれた少なくとも一種を含む成分である。
【００２４】
この本発明で用いられる、重縮合反応に触媒として用いられるチタン化合物成分は、最終製品の触媒に起因する異物を低減する観点から、ポリマー中に可溶なチタン化合物であることが必要であり、該チタン化合物成分としては、下記一般式（Ｉ）で表される化合物、若しくは一般式（ＩＩ）で表される化合物と下記一般式（ＩＩ）で表される芳香族多価カルボン酸又はその無水物とを反応させた生成物である必要がある。
【００２５】
【化９】

【００２６】
【化１０】

【００２７】
ここで、一般式（Ｉ）で表されるチタンアルコキシドとしては、具体的にはテトライソプロポキシチタン、テトラプロポキシチタン、テトラ−ｎ−ブトキシチタン、テトラエトキシチタン、テトラフェノキシチタン、オクタアルキルトリチタネート、及びヘキサアルキルジチタネートなどが好ましく用いられる。
【００２８】
また、本発明の該チタンアルコキシドと反応させる一般式（ＩＩ）で表される芳香族多価カルボン酸又はその無水物としては、フタル酸、トリメリット酸、ヘミメリット酸、ピロメリット酸及びこれらの無水物が好ましく用いられる。
【００２９】
上記チタンアルコキシドと芳香族多価カルボン酸又はその無水物とを反応させる場合には、溶媒に芳香族多価カルボン酸又はその無水物の一部または全部を溶解し、この混合液にチタンアルコキシドを滴下し、０〜２００℃の温度で少なくとも３０分間、好ましくは３０〜１５０℃の温度で４０〜９０分間加熱することによって行われる。この際の反応圧力については特に制限はなく、常圧で十分である。なお、芳香族多価カルボン酸またはその無水物を溶解させる溶媒としては、エタノール、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、ベンゼン及びキシレン等から所望に応じていずれを用いることもできる。
【００３０】
ここで、チタンアルコキシドと芳香族多価カルボン酸またはその無水物との反応モル比には特に限定はないが、チタンアルコキシドの割合が高すぎると、得られるポリエステルの色調が悪化したり、軟化点が低下したりすることがあり、逆にチタンアルコキシドの割合が低すぎると重縮合反応が進みにくくなることがある。このため、チタンアルコキシドと芳香族多価カルボン酸又はその無水物との反応モル比は、２／１〜２／５の範囲内とすることが好ましい。
【００３１】
本発明で用いられる重縮合用の触媒系は、上記のチタン化合物成分と、下記一般式（ＩＩＩ）により表されるリン化合物とを含むものであり、両者の未反応混合物から実質的になるものである。
【００３２】
【化１１】

【００３３】
上記一般式（ＩＩＩ）のリン化合物（ホスホネート化合物）としては、カルボメトキシメタンホスホン酸、カルボエトキシメタンホスホン酸、カルボプロポキシメタンホスホン酸、カルボブトキシメタンホスホン酸、カルボメトキシフェニルメタンホスホン酸、カルボエトキシフェニルメタンホスホン酸、カルボプロトキシフェニルメタンホスホン酸、カルボブトキシフェニルメタンホスホン酸等のホスホン酸誘導体のジメチルエステル類、ジエチルエステル類、ジプロピルエステル類、ジブチルエステル類等から選ばれることが好ましい。
【００３４】
上記のホスホネート化合物は、通常安定剤として使用されるリン化合物に比較して、チタン化合物との反応が比較的緩やかに進行するので、反応中における、チタン化合物の触媒活性持続時間が長く、結果として該チタン化合物のポリエステルへの添加量を少なくすることができる。また、一般式（ＩＩＩ）のリン化合物を含む触媒系に多量に安定剤を添加しても、得られるポリエステルの熱安定性を低下させることがなく、その色調を不良化することが無い。
【００３５】
本発明では、上記のチタン化合物成分とリン化合物とを含む触媒が、下記数式（１）及び（２）を同時に満足するものである必要がある。
【００３６】
【数３】

【００３７】
ここで、（Ｐ／Ｔｉ）は１以上１５以下であるが、２以上１５以下であることが好ましく、さらには２以上１０以下であることが好ましい。この（Ｐ／Ｔｉ）が１未満の場合、ポリエステルの色相が黄味を帯びたものとなるので、好ましくない。また、（Ｐ／Ｔｉ）が１５を越えるとポリエステルの重縮合反応性が大幅に低下し、目的とするポリエステルを得ることが困難となる。この（Ｐ／Ｔｉ）の適正範囲は通常の金属触媒系よりも狭いことが特徴的であるが、適正範囲にある場合、本発明のような従来にない効果を得ることができる。
【００３８】
一方、（Ｔｉ＋Ｐ）は１０以上１００以下であるが、２０以上７０以下であることがより好ましい。（Ｔｉ＋Ｐ）が１０に満たない場合は、製糸プロセスにおける生産性が大きく低下し、満足な性能が得られなくなる。また、（Ｔｉ＋Ｐ）が１００を越える場合には、触媒に起因する異物が少量ではあるが発生し好ましくない。
【００３９】
上記式中、Ｔｉの量としては２〜１５ミリモル％程度が適当である。
【００４０】
本発明で用いられているポリエステルポリマーは、上記のチタン化合物成分とリン化合物とを含む触媒の存在下に芳香族ジカルボキシレートエステルを重縮合して得られるポリマーであるが、本発明においては、芳香族ジカルボキシレートエステルが、芳香族ジカルボン酸と脂肪族グリコールからなるジエステルであることが好ましい。
【００４１】
ここで芳香族ジカルボン酸としては、テレフタル酸を主とすることが好ましい。より具体的には、テレフタル酸が全芳香族ジカルボン酸を基準として７０モル％以上を占めていることが好ましく、さらには該テレフタル酸は、全芳香族ジカルボン酸を基準として８０モル％以上を占めていることが好ましい。ここでテレフタル酸以外の好ましい芳香族ジカルボン酸としては、例えば、フタル酸、イソフタル酸、ナフタレンジカルボン酸、ジフェニルジカルボン酸、ジフェノキシエタンジカルボン酸等を挙げることができる。
【００４２】
もう一方の脂肪族グリコールとしては、アルキレングリコールであることが好ましく、例えば、エチレングリコール、トリメチレングリコール、プロピレングリコール、テトラメチレングリコール、ネオペンチルグリコール、ヘキサンメチレングリコール、ドデカメチレングリコールを用いることができるが、特にエチレングリコールであることが好ましい。
【００４３】
本発明ではポリエステルが、ポリエチレンテレフタレートであることが特に好ましい。ここでポリエステルが、テレフタル酸とエチレングリコールからなるエチレンテレフタレートを主たる繰り返し単位とするポリエステルであることも好ましい。ここで「主たる」とは該エチレンテレフタレート繰り返し単位がポリエステル中の全繰り返し単位を基準として７０モル％以上を占めていることをいう。
【００４４】
また本発明で用いるポリエステルは、芳香族ジカルボン酸と脂肪族グリコールからなる主たる繰り返し単位以外に、酸成分またはジオール成分としてポリエステルを構成する成分を共重合した、共重合ポリエステルとしてもよい。
【００４５】
共重合する成分としては、酸成分として、上記の芳香族ジカルボン酸はもちろん、アジピン酸、セバシン酸、アゼライン酸、デカンジカルボン酸などの脂肪族ジカルボン酸、シクロヘキサンジカルボン酸などの脂環式ジカルボン酸などの二官能性カルボン酸成分又はそのエステル形成性誘導体を原料として使用することができる。また、共重合するジオール成分としては上記の脂肪族ジオールはもちろん、シクロヘキサンジメタノールなどの脂環式グリコール、ビスフェノール、ハイドロキノン、２，２−ビス（４−β−ヒドロキシエトキシフェニル）プロパン類などの芳香族ジオールなどを原料として使用することができる。
【００４６】
さらに、トリメシン酸、トリメチロールエタン、トリメチロールプロパン、トリメチロールメタン、ペンタエリスリトールなどの多官能性化合物を原料として共重合させ使用することができる。
【００４７】
これらは一種を単独で用いてもよいし、二種以上を併用してもよい。
【００４８】
本発明においては、上記のような芳香族ジカルボン酸と脂肪族グリコールからなる芳香族ジカルボキシレートエステルが用いられるが、この芳香族ジカルボキシレートエステルは、芳香族ジカルボン酸と脂肪族グリコールとのジエステル化反応により得ることもできるし、あるいは芳香族ジカルボン酸のジアルキルエステルと脂肪族グリコールとのエステル交換反応により得ることもできる。ただし、芳香族ジカルボン酸のジアルキルエステルを原料とし、エステル交換反応を経由する方法とした方が、芳香族ジカルボン酸を原料としジエステル化反応させる方法に比較し、重縮合反応中に安定剤として添加したリン化合物の飛散が少ないという利点がある。
【００４９】
さらに、チタン化合物の一部及び／又は全量をエステル交換反応開始前に添加し、エステル交換反応触媒と重縮合反応触媒との二つの触媒として兼用させることが好ましい。このようにすることにより、最終的にポリエステル中のチタン化合物の含有量を低減することができる。ポリエチレンテレフタレートの例で、さらに具体的に述べると、テレフタル酸を主とする芳香族ジカルボン酸のジアルキルエステルとエチレングリコールとのエステル交換反応を、下記一般式（Ｉ）で表されるチタンアルコキシド、及び下記一般式（Ｉ）で表されるチタンアルコキシドと下記一般式（ＩＩ）で表される芳香族多価カルボン酸又はその無水物とを反応させた生成物からなる群から選ばれた少なくとも１種を含むチタン化合物成分の存在下に行い、このエステル交換反応により得られた、芳香族ジカルボン酸とエチレングリコールとのジエステルを含有する反応混合物に、更に下記一般式（ＩＩＩ）により表されるリン化合物を添加し、これらの存在下に重縮合することが好ましい。
【００５０】
【化１２】

【００５１】
【化１３】

【００５２】
【化１４】

【００５３】
なお、該エステル交換反応を行う場合には通常は常圧下で実施されるが、０．０５〜０．２０ＭＰａの加圧下に実施すると、チタン化合物成分の触媒作用による反応が更に促進され、かつ副生物のジエチレングリコールが大量に発生することもないので、熱安定性などの特性が更に良好なものとなる。温度としては１６０〜２６０℃が好ましい。
【００５４】
また、本発明において、芳香族ジカルボン酸がテレフタル酸である場合には、ポリエステルの出発原料としてテレフタル酸及びテレフタル酸ジメチルが用いられるが、その場合にはポリアルキレンテレフタレートを解重合することによって得られた回収テレフタル酸ジメチル又はこれを加水分解して得られる回収テレフタル酸を、ポリエステルを構成する全酸成分の質量を基準として７０質量％以上使用することもできる。この場合、前記ポリアルキレンテレフタレートは、ポリエチレンテレフタレートであることが好ましく、特に回収されたＰＥＴボトル、回収された繊維製品、回収されたポリエステルフィルム製品、さらには、これら製品の製造工程において発生するポリマー屑などをポリエステル製造用原料源とする再生ポリエステルを用いることは、資源の有効活用の観点から好ましいことである。
【００５５】
ここで、回収ポリアルキレンテレフタレートを解重合してテレフタル酸ジメチルを得る方法には特に制限はなく、従来公知の方法をいずれも採用することができる。また、上記、回収された、テレフタル酸ジメチルからテレフタル酸を回収する方法にも特に制限はなく、従来方法のいずれを用いてもよい。テレフタル酸に含まれる不純物については、４−カルボキシベンズアルデヒド、パラトルイル酸、安息香酸及びヒドロキシテレフタル酸ジメチルの含有量が、合計で１ｐｐｍ以下であることが好ましい。また、テレフタル酸モノメチルの含有量が、１〜５０００ｐｐｍの範囲にあることが好ましい。回収されたテレフタル酸と、アルキレングリコールとを直接エステル化反応させ、得られたエステルを重縮合することによりポリエステルを製造することができる。
【００５６】
本発明では、ポリエステルが上記のような再生ポリエステルであることがより好ましい。
【００５７】
本発明で用いられるポリエステルの固有粘度は、０．４０〜０．８０の範囲にあることが好ましく、さらに０．４５〜０．７５、特に０．５０〜０．７０の範囲が好ましい。固有粘度が０．４０未満であると、繊維の強度が不足するため好ましくない。他方、固有粘度が０．８０を越えると、原料ポリマーの固有粘度を過剰に引き上げる必要があり不経済である。
【００５８】
本発明で用いるポリエステルは、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く、特に艶消剤として酸化チタン、安定剤としての酸化防止剤は好ましく添加され、酸化チタンとしては、平均粒径が０．０１〜２μｍの酸化チタンを、最終的に得られるポリエステル組成物中に０．０１〜１０重量％含有させるように添加することが好ましい。
【００５９】
また、酸化防止剤としては、ヒンダードフェノール系の酸化防止剤が好ましいが、ヒンダードフェノール系酸化防止剤の添加量は１重量％以下であることが好ましい。１重量％を越えると製糸時のスカムの原因となり得る他、１重量％を越えて添加しても溶融安定性向上の効果が飽和してしまう為好ましくない。ヒンダードフェノール系酸化防止剤の添加量は０．００５〜０．５重量％の範囲が更に好ましい。またこれらヒンダードフェノール系酸化防止とチオエーテル系二次酸化防止剤を併用して用いることも好ましく実施される。
【００６０】
該酸化防止剤のポリエステルへの添加方法は特に制限はないが、好ましくはエステル交換反応、またはエステル化反応終了後、重合反応が完了するまでの間の任意の段階で添加する方法が挙げられる。
【００６１】
本発明においては、上記した方法で得られたポリエステルポリマーを、従来公知のポリエステルの溶融紡糸により紡糸することにより、縫糸用ポリエステル繊維を得ることができる。
【００６２】
上記縫糸用ポリエステル繊維の繊度は５００ｄｔｅｘ未満、且つ強度が６．０ｃＮ／ｄｔｅｘ以上であることが好ましい。
【００６３】
さらに、本発明においては、上記の縫糸用ポリエステル繊維に、常法に従って撚糸を加え、或いは無撚の状態で染色することにより、縫糸とすることができる。
【００６４】
【実施例】
以下、本発明を更に下記実施例により具体的に説明するが、本発明の範囲はこれら実施例により何等限定を受けるものではない。なお、実施例中の各物性値は以下の方法に従って求めた。
【００６５】
（１）固有粘度：
ポリエステルポリマーの固有粘度は、３５℃オルソクロロフェノール溶液にて、常法に従って３５℃において測定した粘度の値から求めた。
【００６６】
（２）ポリエステル中のチタン、リン含有量：
サンプルをアルミ板上で加熱溶融した後、圧縮プレス機で平面を有する成型体に形成し、蛍光Ｘ線測定装置（理学電機工業株式会社製３２７０型）に供して、定量分析した。
【００６７】
（３）ジエチレングリコール（ＤＥＧ）量：
抱水ヒドラジンを用いてポリマーを分解し、ガスクロマトグラフィー（株式会社日立製作所製「２６３−７０」）を用い、常法に従って測定した。
【００６８】
（４）色相（カラーＬ値／カラーｂ値）：
粒状のポリマーサンプルを１６０℃×９０分乾燥機中で熱処理し、結晶化させた後、カラーマシン社製ＣＭ−７５００型カラーマシンで測定した。
【００６９】
我々の検討によれば、カラーｂ値が２．５以下の場合、淡色に染色しても色のくすみは発生しない。
【００７０】
（５）繊維の強伸度：
ＪＩＳ Ｌ １０１３記載の方法に準拠して測定した。
【００７１】
（６）紡糸口金に発生する付着物の層：
ポリエステルをチップとなし、これを２９５℃で溶融し、孔径０．３５ｍｍφ、孔数１個の紡糸口金から吐出し、６００ｍ／分で２１日間紡糸し、１、７、１４、２１日目の口金の吐出口外縁に発生する付着物の層の高さを測定した。この付着物層の高さが大きいほど吐出されたポリエステルメルトのフィラメント状流にベンディングが発生しやすく、このポリエステルの成形性は低くなる。すなわち、紡糸口金に発生する付着物層の高さは、当該ポリエステルの成形性の指標であり、０μｍに近い方が当然ながら成形性は良好である。
【００７２】
（７）繊度の斑（イヴネスＵ％）
ツェルベルガー社製ウースターテンソラピッド、ウースター４を用いハーフイナート条件で測定を行った。
【００７３】
（８）染斑
マルチフィラメントを筒編機を用いて筒編とした後、分散染料（ブルー系）を用いて染色をおこない、得られた染上がりの筒編の染色の均一性を目視により判定した。
【００７４】
染斑が無く、均一に染色されている物を良好とし、僅かでも染色斑のあるものを不良とした。
【００７５】
（９）縫製性能
ジュウキ製本縫いミシンにて、オルガン社製ミシン用縫い針ＤＢ−１ ＃１４を用い、針糸張力６０ｇ、下糸張力１５ｇ、縫い目ピッチ１５Ｓ／３ｃｍにて、ポリエステル／レーヨン混のサージ布を４枚重ねた生地を縫製した。
【００７６】
このとき、所定の回転数（ミシンの１分当りの縫い目数）で６０秒糸切れなく縫製できた場合を１０点とし、糸切れが発生した場合は、６秒縫製できる毎に１点とした。すなわち３０秒縫製した時点で糸切れを発生した場合は５点となる。
【００７７】
１０点を得た場合は回転数を５００回転ずつ上げ、同様の評価を行った。
【００７８】
［実施例１］
テレフタル酸ジメチル１００部とエチレングリコール７０部との混合物に、テトラ−ｎ−ブチルチタネート０．００９部を加圧反応が可能なステンレス製容器に仕込み、０．０７ＭＰａの加圧を行い１４０℃から２４０℃に昇温しながらエステル交換反応させた後、トリエチルホスホノアセテート０．０４部を添加し、エステル交換反応を終了させた。
【００７９】
その後、反応生成物を重合容器に移し、２９０℃まで昇温し、２６．６７Ｐａ以下の高真空にて重縮合反応を行って、固有粘度０．６０、ジエチレングリコール量が１．５％であるポリエステルを得た。得られたポリエステルポリマーの品質を表１に示す。
【００８０】
次に得られたポリエステルを常法に従いチップ化し、乾燥した。さらにこのチップを用い、常法に従って紡糸した後、冷却、オイリング、延伸して８４ｄｔｅｘ／２４ｆｉｌのマルチフィラメント延伸糸を得た。
【００８１】
［参考例］
トリメリット酸チタンの合成方法：
無水トリメリット酸のエチレングリコール溶液（０．２％）にテトラブトキシチタンを無水トリメリット酸に対して１／２モル添加し、空気中常圧下で８０℃に保持して６０分間反応させて、その後、常温に冷却し、１０倍量のアセトンによって生成触媒を再結晶化させ、析出物をろ紙によって濾過し、１００℃で２時間乾燥させて、目的とするチタン化合物を得た。
【００８２】
［実施例２］
実施例１において、チタン化合物として、上記参考例の方法にて合成したトリメリット酸チタン０．０１６部に変更したこと以外は実施例１と同様の操作を行った。得られたポリエステルポリマーの品質を表１に示す。
【００８３】
［比較例１］
テレフタル酸ジメチル１００部とエチレングリコール７０部との混合物に、酢酸カルシウム一水和物０．０６４重量部を加圧反応が可能なステンレス製容器に仕込み、０．０７ＭＰａの加圧を行い１４０℃から２４０℃に昇温しながらエステル交換反応させた後、５６重量％濃度のリン酸水溶液０．０４４重量部を添加し、エステル交換反応を終了させた。
【００８４】
その後、反応生成物を重合容器に移し、三酸化二アンチモンを表に示す量を添加して２９０℃まで昇温し、（２６．６７Ｐａ）以下の高真空にて重縮合反応を行ってポリエステルを得た。得られたポリエステルポリマーの品質を表１に示す。
【００８５】
次に得られたポリエステルを常法に従いチップ化し、乾燥した。さらにこのチップを用い、常法に従って紡糸した後、冷却、オイリング、延伸して８４ｄｔｅｘ／２４ｆｉｌのマルチフィラメント延伸糸を得た。
【００８６】
【表１】

【００８７】
また、実施例１と比較例１について、紡糸口金に発生する異物高さとポリエステル繊維の繊度の斑（イヴネスＵ％）、及び染斑について測定した結果を表２に示す。
【００８８】
【表２】

【００８９】
表２から明らかなように、本発明の縫糸用ポリエステル繊維の製造における紡糸口金に発生する異物高さは、アンチモン化合物を触媒として用いた場合に比べ、大幅に減少し、長時間口金面清掃を行わなくとも、繊度（イヴネスＵ％）の斑が少なく、且つ染色安定性に優れた縫糸用糸ポリエステル繊維が得られる。
【００９０】
更に、実施例１と比較例１のポリエステルフィラメントに、イタリー撚糸機を用いて、下撚り（Ｓ方向）８５０ｔ／ｍの撚を与えた後、該下撚り糸を３本引き揃え、５６０ｔ／ｍの上撚り（Ｚ方向）を与えた。
【００９１】
得られた撚糸を、常法に従い、クラッシュチーズボビンに巻取り、チーズ染色機にて染色を行い、還元洗浄後、乾燥し、シリコン系油剤を３％付与し、縫糸を得た。
【００９２】
得られた縫糸を一般的な本縫いミシン機を用いて縫製を行い縫製性能を評価した。その結果を表３に示す。
【００９３】
【表３】

【００９４】
表３から明らかなように、本発明のポリエステル繊維からなる縫糸はアンチモン触媒を用いた場合（比較例１）と比べて何ら遜色のない良好な性能を有するものであった。
【００９５】
また、該縫糸は、カラーｂ値が低いために淡色の染色を行っても、色のくすみの問題は発生しなかった。
【００９６】
【発明の効果】
本発明によれば、良好な色調（カラーｂ値）を有し、紡糸口金を通して長時間連続的に紡糸しても口金付着物の発生量が非常に少なく、縫糸製造のための撚糸工程における断糸等の発生が少ない上、繊度（イヴネスＵ％）の斑が少なく、且つ染色安定性に優れた縫糸用ポリエステル繊維及び該ポリエステル繊維を用いてなる縫糸が得られる。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a polyester fiber for sewing, and more particularly, has a good color tone (color b value), has a very small amount of deposits attached to a spinneret even when continuously spun through a spinneret for a long time, and manufactures a sewing thread. The present invention relates to a polyester thread for a sewing thread which is less likely to cause breakage and the like in a twisting process for yarn, and has less unevenness in fineness (evenness U%) and excellent dyeing stability, and a sewing thread using the polyester fiber. is there.
[0002]
[Prior art]
Polyester, especially polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate and polytetramethylene terephthalate are widely used in fibers, films and other molded products because of their excellent mechanical, physical and chemical properties. I have.
[0003]
For example, polyethylene terephthalate is usually subjected to a direct esterification reaction between terephthalic acid and ethylene glycol, a transesterification reaction between a lower alkyl ester of terephthalic acid such as dimethyl terephthalate and ethylene glycol, or a reaction between terephthalic acid and ethylene oxide. Reacting to form ethylene glycol ester of terephthalic acid and / or a low polymer thereof, and then subjecting the reaction product to a polycondensation reaction by heating under reduced pressure in the presence of a polymerization catalyst to a predetermined degree of polymerization. Being manufactured. Further, polyethylene naphthalate, polytrimethylene terephthalate, and polytetramethylene terephthalate are also manufactured by the same method as described above.
[0004]
However, it is well known that, depending on the type of catalyst used in these polycondensation reaction stages, the reaction rate and the quality of the obtained polyester are greatly affected, and as a polycondensation catalyst for polyethylene terephthalate, an antimony compound is It 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, when the polyester is continuously melt-spun over a long period of time, foreign substances (hereinafter sometimes simply referred to as die foreign substances) adhere to and accumulate around the die hole, and the molten polymer is deposited. There is a problem that a flow bending phenomenon (bending) occurs, which causes fluff, breakage or unevenness in the spinning and drawing steps.
[0006]
In particular, in sewing applications where unevenness of fineness has a significant effect on the quality of the product, the above-mentioned accumulation of foreign matter on the die may be a fatal defect.
[0007]
In order to avoid this problem, it has been proposed to use a titanium compound such as titanium tetrabutoxide as a polycondensation catalyst other than the antimony compound. However, when such a titanium compound is used, thermal stability is reduced. It is difficult to increase the toughness of the fiber because it is bad and severely deteriorates during melting. Further, the obtained polyester itself is discolored to yellow, and when used for fiber applications, there is a new problem that the color tone of the obtained fiber deteriorates.
[0008]
In order to solve such a problem, for example, Japanese Patent Publication No. 59-46258 discloses a product obtained by reacting a titanium compound with trimellitic acid, and JP-A-58-38722 discloses a titanium compound. It is disclosed that a product obtained by reacting a compound with a phosphite is used as a catalyst for producing a polyester. Certainly, according to these methods, although the melt heat stability of the polyester is improved to some extent, the color tone of the obtained polymer is not sufficient, and thus further improvement of the polymer color tone is desired.
[0009]
Further, JP-A-7-138354 proposes that a complex of a titanium compound and a phosphorus compound is used as a catalyst for polyester production. According to this method, the stability of the melting heat is improved to some extent. However, the effect is not sufficient, and there is a problem that the color tone of the obtained polymer needs to be improved.
[0010]
In addition, these titanium-phosphorus-based catalysts themselves often remain as foreign substances in the polyester polymer, and it has been desired to solve this problem.
[0011]
[Patent Document 1]
Japanese Patent Publication No. 59-46258
[Patent Document 2]
JP-A-58-38722.
[Patent Document 3]
JP-A-7-138354
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to have a good color tone (color b value), and to generate a deposit on a spinneret even after continuous spinning for a long time. A thread polyester fiber for a sewing thread, which has a very small amount of thread breakage and the like in a twisting process for producing a sewing thread, has a small unevenness of fineness (evenness U%), and is excellent in dyeing stability; An object of the present invention is to provide a sewing thread.
[0015]
[Means for Solving the Problems]
Means for Solving the Problems The present inventors have conducted intensive studies on polycondensation catalysts used for the production of polyester in order to solve the above problems, and as a result of repeated studies, have completed the present invention.
[0016]
That is, according to the present invention, there is provided a polyester fiber for a sewing thread composed of a polyester polymer, wherein the polyester polymer polycondensates an aromatic dicarboxylate ester in the presence of a catalyst containing a titanium compound component and a phosphorus compound. A titanium alkoxide represented by the following general formula (I), a titanium alkoxide represented by the following general formula (I), and a titanium alkoxide represented by the following general formula (II) A component containing at least one selected from the group consisting of a product obtained by reacting an aromatic polycarboxylic acid or an anhydride thereof, and wherein the phosphorus compound is a compound represented by the following general formula (III) In addition, the present invention provides a polyester fiber for sewing thread, wherein the content of titanium and phosphorus simultaneously satisfies the following mathematical expressions (1) and (2). That.
[0017]
Embedded image

[0018]
Embedded image

[0019]
Embedded image

[0020]
(Equation 2)

[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0022]
The polyester fiber for sewing thread of the present invention is composed of a polyester polymer, which is a polymer obtained by polycondensing an aromatic dicarboxylate ester in the presence of a catalyst containing a titanium compound component and a phosphorus compound. is there.
[0023]
The titanium compound component used in the present invention includes a titanium alkoxide represented by the following general formula (I), a titanium alkoxide represented by the following general formula (I), and an aromatic polyamine represented by the following general formula (II). It is a component containing at least one selected from the group consisting of a product obtained by reacting a polyvalent carboxylic acid or an anhydride thereof.
[0024]
The titanium compound component used as a catalyst in the polycondensation reaction used in the present invention needs to be a titanium compound soluble in a polymer, from the viewpoint of reducing foreign substances caused by the catalyst of the final product, The titanium compound component includes a compound represented by the following general formula (I) or a compound represented by the following general formula (II) and an aromatic polycarboxylic acid represented by the following general formula (II) or an anhydride thereof. It must be a product obtained by reacting with a substance.
[0025]
Embedded image

[0026]
Embedded image

[0027]
Here, specific examples of the titanium alkoxide represented by the general formula (I) include tetraisopropoxytitanium, tetrapropoxytitanium, tetra-n-butoxytitanium, tetraethoxytitanium, tetraphenoxytitanium, octaalkyltrititanate, And hexaalkyl dititanate are preferably used.
[0028]
Examples of the aromatic polycarboxylic acid represented by the general formula (II) or an anhydride thereof to be reacted with the titanium alkoxide of the present invention include phthalic acid, trimellitic acid, hemi-mellitic acid, pyromellitic acid and the like. Anhydrides are preferably used.
[0029]
When reacting the titanium alkoxide with an aromatic polycarboxylic acid or an anhydride thereof, a part or all of the aromatic polycarboxylic acid or an anhydride thereof is dissolved in a solvent, and the titanium alkoxide is added to the mixed solution. It is carried out by dropping and heating at a temperature of 0 to 200 ° C for at least 30 minutes, preferably at a temperature of 30 to 150 ° C for 40 to 90 minutes. The reaction pressure at this time is not particularly limited, and normal pressure is sufficient. As a solvent for dissolving the aromatic polycarboxylic acid or its anhydride, any of ethanol, ethylene glycol, trimethylene glycol, tetramethylene glycol, benzene, xylene and the like can be used as desired.
[0030]
Here, the reaction molar ratio of the titanium alkoxide and the aromatic polycarboxylic acid or its anhydride is not particularly limited. However, if the proportion of the titanium alkoxide is too high, the color tone of the obtained polyester is deteriorated or the softening point is lowered. May decrease, and conversely, if the proportion of the titanium alkoxide is too low, the polycondensation reaction may not easily proceed. For this reason, the reaction molar ratio between the titanium alkoxide and the aromatic polycarboxylic acid or its anhydride is preferably in the range of 2/1 to 2/5.
[0031]
The catalyst system for polycondensation used in the present invention contains the above-mentioned titanium compound component and a phosphorus compound represented by the following general formula (III), and consists essentially of an unreacted mixture of the two. It is.
[0032]
Embedded image

[0033]
Examples of the phosphorus compound (phosphonate compound) of the above general formula (III) include carbomethoxymethanephosphonic acid, carbethoxymethanephosphonic acid, carbopropoxymethanephosphonic acid, carbbutoxymethanephosphonic acid, carbomethoxyphenylmethanephosphonic acid, and carbethoxyphenyl It is preferably selected from dimethyl esters, diethyl esters, dipropyl esters, dibutyl esters, and the like of phosphonic acid derivatives such as methanephosphonic acid, carboxypropylphenylmethanephosphonic acid, and carbbutoxyphenylmethanephosphonic acid.
[0034]
Since the above-mentioned phosphonate compound proceeds relatively slowly with the titanium compound as compared with the phosphorus compound usually used as a stabilizer, the duration of the catalytic activity of the titanium compound during the reaction is long, and as a result, The amount of the titanium compound added to the polyester can be reduced. Further, even if a large amount of a stabilizer is added to the catalyst system containing the phosphorus compound of the general formula (III), the resulting polyester does not deteriorate in thermal stability and does not deteriorate its color tone.
[0035]
In the present invention, the catalyst containing the titanium compound component and the phosphorus compound needs to satisfy the following mathematical expressions (1) and (2) simultaneously.
[0036]
[Equation 3]

[0037]
Here, (P / Ti) is 1 or more and 15 or less, but is preferably 2 or more and 15 or less, and more preferably 2 or more and 10 or less. When this (P / Ti) is less than 1, the hue of the polyester becomes yellowish, which is not preferable. When (P / Ti) exceeds 15, the polycondensation reactivity of the polyester is greatly reduced, and it is difficult to obtain the desired polyester. Although the proper range of (P / Ti) is characteristically narrower than that of a normal metal catalyst system, when it is within the proper range, an effect which has not been achieved conventionally can be obtained as in the present invention.
[0038]
On the other hand, (Ti + P) is 10 or more and 100 or less, but is more preferably 20 or more and 70 or less. When (Ti + P) is less than 10, the productivity in the spinning process is greatly reduced, and satisfactory performance cannot be obtained. On the other hand, when (Ti + P) exceeds 100, a small amount of foreign matter due to the catalyst is generated, which is not preferable.
[0039]
In the above formula, a suitable amount of Ti is about 2 to 15 mmol%.
[0040]
The polyester polymer used in the present invention is a polymer obtained by polycondensing an aromatic dicarboxylate ester in the presence of a catalyst containing the above titanium compound component and a phosphorus compound, but in the present invention, Preferably, the aromatic dicarboxylate ester is a diester comprising an aromatic dicarboxylic acid and an aliphatic glycol.
[0041]
Here, it is preferable that the aromatic dicarboxylic acid is mainly terephthalic acid. More specifically, terephthalic acid preferably accounts for 70 mol% or more based on the total aromatic dicarboxylic acid, and furthermore, the terephthalic acid accounts for 80 mol% or more based on the total aromatic dicarboxylic acid. Is preferred. Here, preferred aromatic dicarboxylic acids other than terephthalic acid include, for example, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, and the like.
[0042]
The other aliphatic glycol is preferably an alkylene glycol, and for example, ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexane methylene glycol, dodecamethylene glycol can be used. And particularly preferably ethylene glycol.
[0043]
In the present invention, it is particularly preferred that the polyester is polyethylene terephthalate. Here, it is also preferable that the polyester is a polyester containing ethylene terephthalate composed of terephthalic acid and ethylene glycol as a main repeating unit. Here, "main" means that the ethylene terephthalate repeating unit accounts for 70 mol% or more based on all repeating units in the polyester.
[0044]
The polyester used in the present invention may be a copolymerized polyester obtained by copolymerizing a component constituting the polyester as an acid component or a diol component, in addition to the main repeating unit composed of an aromatic dicarboxylic acid and an aliphatic glycol.
[0045]
As the component to be copolymerized, as the acid component, not only the above aromatic dicarboxylic acids, but also adipic acid, sebacic acid, azelaic acid, aliphatic dicarboxylic acids such as decanedicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and the like. The bifunctional carboxylic acid component or an ester-forming derivative thereof can be used as a raw material. Examples of the diol component to be copolymerized include not only the above-mentioned aliphatic diols, but also alicyclic glycols such as cyclohexanedimethanol, aromatic compounds such as bisphenol, hydroquinone, and 2,2-bis (4-β-hydroxyethoxyphenyl) propane. An aromatic diol or the like can be used as a raw material.
[0046]
Further, polyfunctional compounds such as trimesic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, and pentaerythritol can be copolymerized and used as a raw material.
[0047]
These may be used alone or in combination of two or more.
[0048]
In the present invention, an aromatic dicarboxylate ester composed of an aromatic dicarboxylic acid and an aliphatic glycol as described above is used, and the aromatic dicarboxylate ester is a diester of an aromatic dicarboxylic acid and an aliphatic glycol. It can also be obtained by an esterification reaction or a transesterification reaction between a dialkyl ester of an aromatic dicarboxylic acid and an aliphatic glycol. However, the method using a transesterification reaction using a dialkyl ester of an aromatic dicarboxylic acid as a raw material is added as a stabilizer during the polycondensation reaction in comparison with the method of performing a diesterification reaction using an aromatic dicarboxylic acid as a raw material. There is an advantage that scattering of the phosphorus compound is small.
[0049]
Further, it is preferable that a part and / or the whole amount of the titanium compound is added before the start of the transesterification reaction, so that the titanium compound is also used as the two catalysts, the transesterification catalyst and the polycondensation reaction catalyst. By doing so, the content of the titanium compound in the polyester can be finally reduced. More specifically, in the example of polyethylene terephthalate, a transesterification reaction between a dialkyl ester of an aromatic dicarboxylic acid mainly composed of terephthalic acid and ethylene glycol is carried out by a titanium alkoxide represented by the following general formula (I), and At least one selected from the group consisting of products obtained by reacting a titanium alkoxide represented by the following general formula (I) with an aromatic polycarboxylic acid or an anhydride thereof represented by the following general formula (II) The reaction mixture containing a diester of an aromatic dicarboxylic acid and ethylene glycol obtained by the transesterification reaction is performed in the presence of a titanium compound component containing a phosphorus compound represented by the following general formula (III). And it is preferable to carry out polycondensation in the presence of these.
[0050]
Embedded image

[0051]
Embedded image

[0052]
Embedded image

[0053]
When the transesterification is carried out, it is usually carried out under normal pressure. However, when carried out under a pressure of 0.05 to 0.20 MPa, the reaction by the catalytic action of the titanium compound component is further promoted, and Since a large amount of biological diethylene glycol is not generated, properties such as thermal stability are further improved. The temperature is preferably from 160 to 260 ° C.
[0054]
In the present invention, when the aromatic dicarboxylic acid is terephthalic acid, terephthalic acid and dimethyl terephthalate are used as starting materials for the polyester.In this case, it is obtained by depolymerizing polyalkylene terephthalate. The recovered dimethyl terephthalate or the recovered terephthalic acid obtained by hydrolyzing the recovered dimethyl terephthalate can be used in an amount of 70% by mass or more based on the mass of all the acid components constituting the polyester. In this case, the polyalkylene terephthalate is preferably polyethylene terephthalate, and in particular, a recovered PET bottle, a recovered fiber product, a recovered polyester film product, and polymer waste generated in a process of manufacturing these products. It is preferable to use a recycled polyester which is a raw material source for polyester production from the viewpoint of effective utilization of resources.
[0055]
Here, the method for depolymerizing the recovered polyalkylene terephthalate to obtain dimethyl terephthalate is not particularly limited, and any conventionally known method can be employed. The method for recovering terephthalic acid from the recovered dimethyl terephthalate is not particularly limited, and any of the conventional methods may be used. Regarding the impurities contained in terephthalic acid, the total content of 4-carboxybenzaldehyde, paratoluic acid, benzoic acid and dimethyl hydroxyterephthalate is preferably 1 ppm or less. Further, the content of monomethyl terephthalate is preferably in the range of 1 to 5000 ppm. A polyester can be produced by directly subjecting the recovered terephthalic acid and alkylene glycol to an esterification reaction and polycondensing the resulting ester.
[0056]
In the present invention, the polyester is more preferably a recycled polyester as described above.
[0057]
The intrinsic viscosity of the polyester used in the present invention is preferably in the range of 0.40 to 0.80, more preferably 0.45 to 0.75, particularly preferably 0.50 to 0.70. If the intrinsic viscosity is less than 0.40, the strength of the fiber becomes insufficient, which is not preferable. On the other hand, if the intrinsic viscosity exceeds 0.80, it is necessary to raise the intrinsic viscosity of the raw material polymer excessively, which is uneconomical.
[0058]
The polyester used in the present invention may contain a small amount of additives as necessary, for example, a lubricant, a pigment, a dye, an antioxidant, a solid-phase polymerization accelerator, a fluorescent brightener, an antistatic agent, an antibacterial agent, an ultraviolet absorber, and light. Stabilizers, heat stabilizers, light-shielding agents, may also contain a matting agent, etc., especially titanium oxide as a matting agent, an antioxidant as a stabilizer is preferably added, as titanium oxide, the average particle size It is preferable to add 0.01 to 2 μm of titanium oxide so that 0.01 to 10% by weight is contained in the finally obtained polyester composition.
[0059]
As the antioxidant, a hindered phenol-based antioxidant is preferable, and the amount of the hindered phenol-based antioxidant is preferably 1% by weight or less. If it exceeds 1% by weight, it may cause scum at the time of spinning, and if it exceeds 1% by weight, the effect of improving the melt stability is saturated. The addition amount of the hindered phenolic antioxidant is more preferably in the range of 0.005 to 0.5% by weight. It is also preferable to use these hindered phenol-based antioxidants and thioether-based secondary antioxidants in combination.
[0060]
The method of adding the antioxidant to the polyester is not particularly limited, but preferably includes a method of adding the antioxidant at an arbitrary stage after completion of the transesterification reaction or esterification reaction until completion of the polymerization reaction.
[0061]
In the present invention, a polyester fiber for sewing can be obtained by spinning the polyester polymer obtained by the above method by melt spinning of a conventionally known polyester.
[0062]
It is preferable that the fineness of the polyester fiber for sewing thread is less than 500 dtex and the strength is 6.0 cN / dtex or more.
[0063]
Furthermore, in the present invention, a twisted thread can be added to the above-described polyester fiber for a thread according to a conventional method, or dyed in a non-twisted state to obtain a thread.
[0064]
【Example】
Hereinafter, the present invention will be described more specifically with reference to the following Examples, but the scope of the present invention is not limited by these Examples. In addition, each physical property value in an Example was calculated | required according to the following method.
[0065]
(1) Intrinsic viscosity:
The intrinsic viscosity of the polyester polymer was determined from the value of the viscosity measured at 35 ° C. in a 35 ° C. orthochlorophenol solution according to a conventional method.
[0066]
(2) Content of titanium and phosphorus in polyester:
After the sample was heated and melted on an aluminum plate, it was formed into a molded body having a flat surface by a compression press machine, and subjected to a fluorescent X-ray measurement apparatus (Rigaku Denki Kogyo Co., Ltd. model 3270) for quantitative analysis.
[0067]
(3) Amount of diethylene glycol (DEG):
The polymer was decomposed using hydrazine hydrate, and measured by gas chromatography ("263-70" manufactured by Hitachi, Ltd.) according to a conventional method.
[0068]
(4) Hue (color L value / color b value):
The granular polymer sample was heat-treated in a drier at 160 ° C. for 90 minutes to be crystallized, and then measured with a color machine CM-7500 type color machine.
[0069]
According to our study, when the color b value is 2.5 or less, no dull color occurs even when dyed in a light color.
[0070]
(5) Fiber strength and elongation:
It was measured according to the method described in JIS L 1013.
[0071]
(6) Layer of deposits generated on spinneret:
Polyester is formed into chips, which are melted at 295 ° C., discharged from a spinneret having a hole diameter of 0.35 mmφ and one hole, spun at 600 m / min for 21 days, and are closed on days 1, 7, 14, and 21. The height of the layer of the deposits generated on the outer edge of the discharge port was measured. As the height of the deposit layer increases, bending tends to occur in the filamentary flow of the discharged polyester melt, and the moldability of the polyester decreases. That is, the height of the deposit layer generated on the spinneret is an index of the moldability of the polyester, and the moldability is naturally better if it is closer to 0 μm.
[0072]
(7) Unevenness of fineness (evenness U%)
The measurement was performed under half-inert conditions using Worcester Tensor Rapid, Worcester 4 manufactured by Zellberger.
[0073]
(8) After making the spotted multifilament into a tubular knit using a tubular knitting machine, dyeing is performed using a disperse dye (blue), and the dyeing uniformity of the resulting dyed tubular knit is visually determined. did.
[0074]
A uniformly stained product without any spot was evaluated as good, and a slightly stained sample was evaluated as poor.
[0075]
(9) Sewing performance Using a sewing machine DB-1 # 14 manufactured by Organ Co., Ltd., a polyester / rayon blend at a needle thread tension of 60 g, a bobbin thread tension of 15 g, a stitch pitch of 15 S / 3 cm, using a sewing machine made of Juuki. A fabric obtained by stacking four surge cloths was sewn.
[0076]
At this time, 10 points were determined when sewing was performed without thread breakage at 60 rpm for a predetermined number of rotations (number of stitches per minute of the sewing machine), and 1 point was determined for every 6 seconds when thread breakage occurred. . That is, if a thread break occurs at the time of sewing for 30 seconds, five points are given.
[0077]
When 10 points were obtained, the same evaluation was performed by increasing the number of rotations by 500.
[0078]
[Example 1]
To a mixture of 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol, 0.009 part of tetra-n-butyl titanate is charged into a stainless steel container capable of performing a pressure reaction, and pressurized at 0.07 MPa to 140 ° C. to 240 ° C. After the transesterification reaction was performed while raising the temperature to ° C, 0.04 part of triethylphosphonoacetate was added to terminate the transesterification reaction.
[0079]
Thereafter, the reaction product was transferred to a polymerization vessel, the temperature was raised to 290 ° C., and a polycondensation reaction was performed under a high vacuum of 26.67 Pa or less to obtain a polyester having an intrinsic viscosity of 0.60 and a diethylene glycol content of 1.5%. Got. Table 1 shows the quality of the obtained polyester polymer.
[0080]
Next, the obtained polyester was formed into chips according to a conventional method, and dried. Further, after spinning using this chip in accordance with a conventional method, it was cooled, oiled and stretched to obtain a 84 dtex / 24fil multifilament stretched yarn.
[0081]
[Reference example]
Synthesis method of titanium trimellitate:
To a solution of trimellitic anhydride in ethylene glycol (0.2%), add 1/2 mol of tetrabutoxytitanium to trimellitic anhydride, react at 80 ° C. under normal pressure in air, and react for 60 minutes. After cooling to room temperature, the resulting catalyst was recrystallized with 10 times the amount of acetone, and the precipitate was filtered through filter paper and dried at 100 ° C. for 2 hours to obtain the desired titanium compound.
[0082]
[Example 2]
The same operation as in Example 1 was performed, except that in Example 1, the titanium compound was changed to 0.016 part of titanium trimellitate synthesized by the method of the above reference example. Table 1 shows the quality of the obtained polyester polymer.
[0083]
[Comparative Example 1]
A mixture of 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol is charged with 0.064 parts by weight of calcium acetate monohydrate in a stainless steel container capable of performing a pressure reaction, and pressurized at 0.07 MPa to 140 ° C. After the transesterification reaction was performed while the temperature was raised to 240 ° C., 0.044 parts by weight of a 56% by weight phosphoric acid aqueous solution was added to terminate the transesterification reaction.
[0084]
Thereafter, the reaction product was transferred to a polymerization vessel, diantimony trioxide was added in the amount shown in the table, the temperature was raised to 290 ° C., and a polycondensation reaction was carried out under a high vacuum of (26.67 Pa) or lower to obtain a polyester. Obtained. Table 1 shows the quality of the obtained polyester polymer.
[0085]
Next, the obtained polyester was formed into chips according to a conventional method, and dried. Further, after spinning using this chip in accordance with a conventional method, it was cooled, oiled and stretched to obtain a 84 dtex / 24fil multifilament stretched yarn.
[0086]
[Table 1]

[0087]
Table 2 shows the measurement results of the height of the foreign matter generated in the spinneret, the unevenness of the fineness of the polyester fiber (evenness U%), and the spots in Example 1 and Comparative Example 1.
[0088]
[Table 2]

[0089]
As is evident from Table 2, the height of the foreign matter generated in the spinneret in the production of the polyester fiber for sewing thread of the present invention is significantly reduced as compared with the case where an antimony compound is used as a catalyst, and the surface of the spinneret is cleaned for a long time. Even without this, it is possible to obtain a thread polyester fiber for sewing thread having less unevenness of fineness (evenness U%) and excellent dyeing stability.
[0090]
Further, the polyester filaments of Example 1 and Comparative Example 1 were given a twist of 850 t / m by using an Italian twisting machine, and then the three twisted yarns were aligned and 560 t / m. A twist (Z direction) was provided.
[0091]
The obtained twisted yarn was wound up on a crush cheese bobbin according to a conventional method, dyed with a cheese dyeing machine, reduced and washed, dried, and 3% of a silicone oil agent was applied to obtain a sewing thread.
[0092]
The obtained sewing thread was sewn using a general lockstitch sewing machine, and the sewing performance was evaluated. Table 3 shows the results.
[0093]
[Table 3]

[0094]
As is evident from Table 3, the sewing thread made of the polyester fiber of the present invention had good performance comparable to the case where the antimony catalyst was used (Comparative Example 1).
[0095]
Further, since the sewing thread had a low color b value, the problem of dull color did not occur even when a light color was dyed.
[0096]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it has favorable color tone (color b value), even if it spins continuously through a spinneret for a long time, the generation amount of a spinneret attachment is very small, and the breakage in the twisting process for sewing thread production. A polyester fiber for a sewing thread, which has less unevenness in fineness (evenness U%) and has excellent dyeing stability, and a sewing thread using the polyester fiber, is obtained.

Claims (7)

A polyester thread for sewing composed of a polyester polymer, wherein the polyester polymer is a polymer obtained by polycondensing an aromatic dicarboxylate ester in the presence of a catalyst containing a titanium compound component and a phosphorus compound, The titanium compound component comprises a titanium alkoxide represented by the following general formula (I), a titanium alkoxide represented by the following general formula (I), and an aromatic polycarboxylic acid represented by the following general formula (II) or the same. A component containing at least one selected from the group consisting of a product obtained by reacting with an anhydride, the phosphorus compound being a compound represented by the following general formula (III), and a content of titanium and phosphorus. Satisfies the following mathematical expressions (1) and (2) at the same time.

The aromatic dicarboxylate ester is a diester obtained by a transesterification reaction between a dialkyl ester of an aromatic dicarboxylic acid and an aliphatic glycol in the presence of a catalyst containing a titanium compound component, and the titanium compound component is represented by the following general formula: Formation by reacting a titanium alkoxide represented by the formula (I) and a titanium alkoxide represented by the following general formula (I) with an aromatic polycarboxylic acid represented by the following general formula (II) or an anhydride thereof The polyester fiber for a sewing thread according to claim 1, which is a component containing at least one selected from the group consisting of:

3. The polyester fiber for sewing thread according to claim 1, wherein the polyester polymer is polyethylene terephthalate. The polyester fiber for sewing thread according to any one of claims 1 to 3, wherein the polyester has a color b value of 2.5 or less. The polyester fiber for sewing thread according to any one of claims 1 to 4, wherein the polyester is a recycled polyester. The polyester fiber for sewing thread according to any one of claims 1 to 5, wherein the fineness of the fiber is less than 500 dtex, and the strength is 6.0 cN / dtex or more. A sewing thread, wherein the fiber according to any one of claims 1 to 6 is twisted or dyed in an untwisted state.