JP2004211267A

JP2004211267A - Spinneret for producing conjugate multifilament fiber, method for producing fiber by using the same spinneret, conjugate multifilament thin fiber obtained by the same method and woven or knitted fabric by using the same thin fiber

Info

Publication number: JP2004211267A
Application number: JP2003002538A
Authority: JP
Inventors: Danichi Ichikawa; 団一市川
Original assignee: Mitsubishi Rayon Co Ltd
Current assignee: Mitsubishi Rayon Co Ltd
Priority date: 2003-01-08
Filing date: 2003-01-08
Publication date: 2004-07-29

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conjugate spinneret capable of obtaining a potentially crimping type conjugate polyester multifilament, especially the fiber of a thin fineness stably, a method for producing the same fiber effectively, the conjugate polyester thin fiber capable of obtaining a uniform dyeing, and a woven or knit fabric obtained by using the same fiber, having sufficient bulky feeling and stretching property. <P>SOLUTION: This ejection hole 10 of the conjugate spinneret is equipped with an ejection opening part 14 of which cross-sectional area increases from its upstream side towards an ejection end and a thin tubular part 13 having a uniform diameter and installed at the upstream side of the ejection opening part as connected with it, where two kinds of polyesters are conjugated. Gradually increased angles made by the axis of the ejection opening part 14 with its wall surface are changed by ≥2 steps with the gradually increased angle of θ1, θ2, etc., within a range of 10-45°. By using the spinneret and spinning continuously under a specific condition, kneeling does not occur even on spinning the thin fiber, and it becomes possible to perform the stable spinning of the fiber having the desired potentially crimping property. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、衣料用途、インテリア用途等の織編物に用いられる潜在捲縮型の高ストレッチ複合繊維用の紡糸口金、その口金を使った複合マルチフィラメント繊維の製造方法、同製造方法により得られる細繊維及び同繊維を使った織編物に関する。
【０００２】
【従来の技術】
従来も、溶融粘度の異なる２種の熱可塑性ポリエステルを同一吐出孔より吐出する複合紡糸により接合型複合繊維糸とし、熱処理によりスパイラル型クリンプを発現させ捲縮型ストレッチ糸とすることが知られており、高捲縮を得るために、用いる２種の熱可塑性ポリエステルの溶融粘度差を大きくすること、また例えば特開平３−６９６４７号公報では高溶融粘度成分として高収縮性のポリエステルを用いることが知られている。しかし、溶融粘度が異なる２種類のポリエステルを張り合わせて紡出する際、両ポリエステルのバラス効果の違いにより、紡出糸は高粘度成分側に大きく屈曲するニーリング現象（ベンディング現象）が発生することも知られている。接合型複合流を紡出する際の両成分の溶融粘度差が大きいほどニーリング現象は大きくなり製糸性は悪化する。このため織編物、特に織物において十分なふくらみ感とストレッチ性を提供できる潜在捲縮型ストレッチ繊維を安定に製造することは難しい。
【０００３】
特開平８−３０２５１８号公報には、２種類のポリマ−流をそれぞれ吐出させ、吐出後に互いを合流させることでニーリング現象を回避する紡糸口金が提案されている。しかしこのような紡糸口金はその吐出孔の製作精度が複合流の形成に大きく影響し、安定な紡糸状態を確保することが難しい。また、高価な紡糸口金となることから、工業的に採用することは難しい。
【０００４】
一方、繊維製品の多色表現の手段の一つとして霜降り効果を与える太細繊維が知られ、この太細繊維は、比較的配向度の低い未延伸糸を低倍率延伸することにより得られる。そして、霜降り調外観を有する伸縮性のある織編物を得る場合、霜降り効果を与える太細繊維と伸縮性を与える繊維とからなる混繊糸を用いて織編物とする方法が知られている。しかしながら、かかる混繊糸を得るには工程が煩雑でコストアップを招くだけでなく、混繊された２種の繊維の染色性の差異に起因する染色時の温度変更、制御等の取扱い上の問題も発生する。
【０００５】
こうした課題を解決するとともに、衣料用途、インテリア用途等の織編物に用いられる潜在捲縮型の高ストレッチ複合繊維を安定して紡糸するために好適な紡糸口金が、例えば特開平１１−３６１４８号公報、特開平１１−１０７０５０号公報、特開平１１−２００１５５号公報、特開２０００−１６０４４３号公報などにより提案されている。
【０００６】
特に、前記紡糸口金の具体的構成を規定する特開平１１−１０７０５０号公報によれば、任意の断面形状を有すると共に、その断面積が上流側から下流側へ向けて漸増する多角錐台形状の吐出開口部と、同吐出開口部の上流側に連設され、２種類のポリエステルが複合される均一径の細管部とを備え、前記吐出開口部はその中心軸と壁面とのなす漸増角度θが１０°〜２５°が提案されている。
【０００７】
ポリエステルＡ及びポリエステルＢを用いて、複合紡糸方法により接合型複合繊維として製造する場合、一般には異なる溶融特性を有する２成分ポリエステルを接合型複合流として溶融紡出する際にはニーリングが発生して製糸安定性を低下させてしまう。そのため、前記公報では前記接合型複合流を紡出する際の吐出線速度を小さくして安定した製糸を実現している。
【０００８】
吐出線速度を低減させるためには、紡糸口金の吐出孔面積を大きくすることが有効であり、本発明のポリエステルＡとポリエステルＢとの複合流を安定して紡出するのに必要な吐出孔開口部の直径は、前記複合流の吐出線速度が１４ｃｍ／秒以下となるように設定される。しかしながら、吐出線速度を低減させることを目的として、単に吐出孔径を大きくした場合、紡糸口金の圧力損失が小さくなり、マルチフィラメントを形成させるための各々の吐出孔への溶融ポリエステルの分配が不均一となる。更には、吐出圧力が極度に低下して吐出線速度に変動が生じ、その結果、糸長方向に脈動が起こり繊維の太さ斑が発生したり、また、ドラフト率が大きくなり糸切れが発生する等の問題が生じてしまう。
【０００９】
前記漸増角度θが１０°未満では、前記吐出開口部の下端にある吐出開口が所定の径となるまで、前記吐出開口部を延在させなければならず、その長さ寸法が大きくなるため、紡糸口金が大型化し、製造コストが大きくなるといった不都合を生じる。また、前記漸増角度θを２５°より大きとすると、前記吐出開口部での圧力変化が大きくなり、糸切れが発生しやすくなるので好ましくない。
【００１０】
上述のように、紡糸口金の各吐出孔内に細管部を設けているため、同吐出孔間での溶融ポリエステルの均一分配を可能にするために充分な圧力損失を得ることができる。更に、前記細管部に連設して形成された前記吐出開口部が、上流側から下流側に向けて断面積を漸増させる形状であり、その漸増角度θを１０°〜２５°に設定すると同時に、紡糸ドラフト率が８００を越えない範囲で前記紡糸口金の吐出開口部の外径と引取り速度とを設定することで、安定した紡出状態を確保する。
【００１１】
【特許文献１】
特開平３−６９６４７号公報
【特許文献２】
特開平８−３０２５１８号公報
【特許文献３】
特開平１１−３６１４８号公報
【特許文献４】
特開平１１−１０７０５０号公報
【特許文献５】
特開平１１−２００１５５号公報
【特許文献６】
特開２０００−１６０４４３号公報
【００１２】
【発明が解決しようとする課題】
しかし、このような紡糸口金はその吐出孔の寸法が複合流の形成に大きく影響する。特に細繊維を安定して紡糸する紡糸口金にあっては、その吐出孔の寸法に加えて形状も複合流の形成に大きく影響し、紡糸の安定性を損なう。すなわち、、上記特許文献４に記載されているように単に多角錐台形状とするだけでは、細管部と多角錐台の吐出孔との境界部において発生するニーリングにより繊維が切断することが多い。このニーリングの発生は、単に前記吐出孔を高精度に製作するだけでは解決し得ない。また、使用に際しては、前記吐出孔の開口端にポリエステル等が付着してその寸法に若干の狂いが生じることがあるが、その場合に安定な紡糸状態を確保することが困難となり、頻繁に洗浄しなければならないという課題も残る。
【００１３】
すなわち本発明は、工業的に簡素な製造工程により複合ポリエステル繊維を安定して製造することのでき、特にその細繊維を安定して得られる紡糸口金と同繊維の効果的な製造方法を提供する。また、織編物として十分なふくらみ感とストレッチ性とを有し、均一な染色が得られる潜在捲縮型の複合ポリエステル細繊維と同繊維を織編物を提供する。
【００１４】
【課題を解決するための手段及び作用効果】
そこで、本発明は、２種類のポリエステルが独立して供給され、両者を接合して吐出する接合型の潜在捲縮複合ポリエステル繊維を溶融紡糸するための紡糸口金であって、任意の断面形状を有すると共に、その断面積が上流側から下流側へ向けて漸増する吐出開口部と、同吐出開口部の上流側に連設され、２種類のポリエステルが複合される均一径の細管部とを備え、前記吐出開口部がその中心軸と壁面とのなす漸増角度θが不連続であることを特徴とするポリエステル複合マルチフィラメント繊維用紡糸口金を主要な構成としている。
【００１５】
すなわち、本発明にあっては、上記特許文献５のごとく、吐出開口部を単なる多角錐台形状に形成するのではなく、その吐出開口部の漸増角度θを不連続に漸増させている。これを換言するならば、吐出開口部の吐出開口端に向けて拡開する開口角度（漸増角度）θを、段階的に順次漸増するように変化させている。その結果、上記細管部と吐出開口部との境界部において発生するニーリング現象による繊維の屈曲による吐出開口部との接触を瞬時に断つと同時に更なる曲がりをも許容できるようになり、たとえそれが細繊維であっても糸切れを大幅に低減できて、紡糸の安定性が確保されるようになる。また、本発明にあっても、上述のように、紡糸口金の各吐出孔内に細管部を設けているため、同吐出孔間での溶融ポリエステルの均一分配を可能にするために充分な圧力損失を得ることができる。
【００１６】
前記吐出開口部の中心軸と壁面とのなす漸増角度θを１０°〜４５°の範囲内において不連続に漸増させることが望ましい。例えば、細管部と吐出開口部との境界部における第１段目の漸増角度θ１を上記特許文献４と同様に１０°〜２０°の範囲に設定すると共に、第２段目の漸増角度θ２を２０°〜４５°に拡げる。その結果、前述の機能に加えて加工のしやすさと洗浄などメンテナンスとの容易性が確保される。この場合、前記細管部の内径Ｄ１が０．４ｍｍ以下であって、細管部の長さＬ１と内径Ｄ１との比（Ｌ／Ｄ）が１．５〜５．０、前記吐出開口部の径Ｄ２が０．５ｍｍ以上の吐出孔であれば更に好ましい。
【００１７】
前記漸増角度θが１０°未満の場合、前記吐出開口部の下端にある吐出開口が所定の径となるまで、前記吐出開口部を延在させなければならず、その長さ寸法が大きくなるため、紡糸口金が大型化し、製造コストが大きくなるといった不都合が生じる。また、通常、テーパー角が２５°より大きい場合は、オリフィス内の圧力変化が大きくなり糸切れが発生するだけでなく品質にも影響するが、本発明の紡糸口金によれば最終段の漸増角度θが４５°まで、前記吐出開口部での圧力変化が安定しており、糸切れの発生が殆どなく、安定した紡糸が可能となる。
【００１８】
前記細管部の内径Ｄ１が０．４ｍｍを越えると、ニーリングが激しく糸切れが多発し、同時に長さＬと内径Ｄとの比（Ｌ／Ｄ）が１．５より小さいと細管部において十分な圧力損失が得られず、ニーリング現象が初期に発生し、繊維の太さ斑が大きくなるだけでなく、更に糸切れが多くなり、安定した製糸ができなくなる。Ｌ／Ｄの値が５．０を越えると、ＬがＤに比較して相対的に長くなり、紡糸口金の厚みが一定であるときに、吐出開口端を所望の大きな径としようとすれば、吐出開口部の長さを更に長くせざるを得なくなる。吐出開口端の口径は、０．５ｍｍ以上が好ましく用いられる。
【００１９】
本発明における第２の基本的な構成は、上述した本発明に特有の構造をもつ紡糸口金を使用し、溶融粘度の異なる２種類の高粘度ポリエステルＡと低粘度ポリエステルＢとの接合型潜在捲縮ポリエステル複合マルチフィラメント繊維の製造方法にある。高粘度ポリエステルＡと低粘度ポリエステルＢは、下記の式（１）〜（２）を満足する必要がある。本発明による複合マルチフィラメント繊維の製造方法は、上記紡糸口金の上流で高粘度ポリエステル（Ａ）と低粘度ポリエステル（Ｂ）との複合流とし、吐出線速度３．５ｍ／分以上、紡糸ドラフト８００以上で前記吐出開口部から吐出させ、未延伸糸繊維の太さ斑の変動係数Ｕ％（Ｌ）を０．８％以下とすることを特徴としている。
【００２０】
４／６≦Ｗ≦６／４（１）
［η］Ａ−［η］Ｂ＞０．１４５（２）
但し、式中、［η］Ａ、［η］ＢはそれぞれＡ、Ｂの固有粘度、ＷはＡ／Ｂの接合比（重量比）を示す。
【００２１】
前記ポリエステルＡとして、テレフタル酸成分を８８〜９８モル％及び炭素数４〜１２の脂肪族ジカルボン酸成分を２〜１２モル％含むジカルボン酸成分と、１，４−ブタンジオール及び平均分子量４００〜４０００のポリテトラメチレングリコールを主とするジオール成分とから構成され、前記ポリテトラメチレングリコールは同ポリエステルＡの全量に対して１５〜３５重量％含有され、融点が１８０℃以上である共重合ポリマーを採用し、前記ポリエステルＢとして、実質的にテトラメチレンテレフタレート単位からなり、融点が２１０℃〜２３０℃であるポリマーを採用し、前記ポリエステルＡとポリエステルＢとの重量比を６／４〜４／６に設定して、上記紡糸口金の上流で複合流とし、同複合流の吐出線速度を１４ｃｍ／秒以下で前記吐出開口部から吐出させること、を含んでなることを特徴とする潜在捲縮複合ポリエステル繊維の製造方法をも主要な構成としている。
【００２２】
前記ポリエステルＡのジカルボン酸成分に脂肪族ジカルボン酸成分が含まれているため、前記ポリエステルＡとポリエステルＢとを複合して最終的に得られる複合ポリエステル繊維はその結晶化特性が向上するとともに捲縮発現性能も向上する。また、前記複合繊維を溶融紡糸する際に、前記脂肪族ジカルボン酸成分を含む前記ポリエステルＡの乾燥チップを紡糸機に供給した際にもチップ同士が接着したり、或いはチップが容器壁面に付着する等の問題が生じることなく、ポリエステルチップの取扱性も向上する。また、織編物としても十分なふくらみ感とストレッチ性を示す。。更には、前記共重合ポリエステルを片側成分として用いた前記複合繊維は、一般的な熱可塑性重合体の溶融紡糸工程により容易且つ安定して溶融賦形することが可能である。
【００２３】
ポリエステルＡに含まれる脂肪族ジカルボン酸は全ジカルボン酸成分を基準として２〜１２モル％共重合させることが好ましい。脂肪族ジカルボン酸の全ジカルボン酸成分における共重合量が２モル％未満であると、前記ポリエステルＡとポリエステルＢとを複合して得られる複合ポリエステル繊維の結晶化特性の向上効果や捲縮発現性能の向上効果が不充分となる。一方、脂肪族ジカルボン酸の全ジカルボン酸成分における共重合量が１２モル％を越えると、ポリエステルＡの結晶性が次第に低下し、前記ポリエステルＡとポリエステルＢとの複合繊維の更なる捲縮発現性能の向上効果も期待できないばかりでなく、前記ポリエステルＡのチップの取扱性も低下する。
【００２４】
ポリエステルＡのジカルボン酸成分には、テレフタル酸成分及び脂肪族ジカルボン酸以外の他のジカルボン酸成分を、本発明の目的を損なわない範囲で少量併用してもよい。ただし、その場合にもポリエステルＡの融点が１８０℃以上であることは必要である。ポリエステルＡの融点が１８０℃を下回る場合には、ポリエステルＡの熱安定性が低下し、更にはポリエステルＢと複合溶融紡糸する際の工程安定性も悪化するので好ましくない。
【００２５】
テレフタル酸成分及び脂肪族ジカルボン酸以外の他のジカルボン酸成分としては、イソフタル酸、５−スルホイソフタル酸又は２−スルホイソフタル酸、１，８ジカルボキシナフタレン−３−スルホン酸等のアルカリ金属塩、ナフタレンジカルボン酸、ジフェニルジカルボン酸、ジフェニルスルホンジカルボン酸、アジピン酸、セバシン酸、１，４−シクロヘキサンジカルボン酸等のジカルボン酸類、又はこれらのエステル形成性誘導体、ｐ−オキシ安息香酸、ｐ−β−オキシエトキシ安息香酸等のオキシカルボン酸類、又はこれらのエステル形成性誘導体、５−テトラブチルホスホニウムスルホイソフタル酸、５−テトラフェニルホスホニウムスルホイソフタル酸、５−フェニルトリブチルホスホニウムスルホイソフタル酸、５−ブチルトリフェニルホスホニウムスルホイソフタル酸等のスルホン酸ホスホニウム塩含有ジカルボン酸類、又はこれらのエステル形成性誘導体等があげられる。
【００２６】
ポリエステルＡのジオール成分としては、１，４−ブタンジオールとポリテトラメチレングリコールとを主成分として用いる。ポリエステルＡのジオール成分として、１，４−ブタンジオールを用いるのは、ポリエステルＡの結晶化速度を向上させると共に、同ポリエステルＡとポリエステルＢとから最終的に得られる複合繊維の捲縮発現特性を向上させるためである。更に、ジオール成分として１，４−ブタンジオールを含む場合には、ポリエステルＡのチップの取扱性が向上する。また、上述のジオール成分ではなく、例えばエチレングリコール等の他のジオール成分を主成分として用いた場合には、ポリエステルの結晶化速度が充分ではなく、その結果、ポリエステルの結晶形成が不充分となり、チップの取扱性が低下するばかりでなく、ポリエステルＢと複合紡糸されて得られる複合繊維の捲縮発現特性も不充分なものとなる。
【００２７】
ポリエステルＡに含まれるポリテトラメチレングリコールとしては、平均分子量が４００〜４０００のものが採用できるが、特に平均分子量が８００〜３０００のものが好ましい。平均分子量が４００未満のポリテトラメチレングリコールが含まれたポリエステルは、同ポリエステルを片側成分としてポリエステルＢと複合紡糸した場合に、得られた複合繊維は充分な捲縮発現性能を備えておらず、また、平均分子量が４０００を越えるポリテトラメチレングリコールが含まれている場合には、均一なポリエステルを得難く、そのようなポリエステルを片側成分としてポリエステルＢと複合紡糸して得られた複合繊維は捲縮発現性能が低いものとなる。
【００２８】
なお、本発明においては、ポリエステルＡに含まれるポリテトラメチレングリコールとして、平均分子量が４００〜４０００の範囲にあれば、平均分子量が異なる複数種のポリテトラメチレングリコールを混合して用いることもできる。
【００２９】
これらのポリエステルＡ及びポリエステルＢを複合しながら上記紡糸口金を使って紡糸するとき、紡糸ドラフト率が８００を越えない範囲で適切な前記紡糸口金の吐出開口端の内径と引取り速度とを設定することで、安定した紡出状態を確保することが可能となる。この紡糸ドラフト率は、吐出開口端の開口径と引取速度とによって適宜決定される。
【００３０】
ポリエステルＡ及びポリエステルＢを用いて、複合紡糸方法により接合型複合繊維として製造することが可能であるが、一般には、異なる溶融特性を有する２成分ポリエステルを接合型複合流として溶融紡出する際にはニーリングが発生して製糸安定性を低下させてしまう。そのため、本発明の製造方法においては、前記接合型複合流を紡出する際の吐出線速度を小さくすることが、安定した製糸を実現するために必要となる。
【００３１】
本発明ではこれらの対策として、各吐出孔間への溶融ポリエステルの均一分配を可能とするに十分な圧力損失が得られる細管部を吐出孔内に確保し、その細管部から吐出開口部に向けて口径が不連続に拡大する吐出開口孔形状を採用するとともに、紡糸ドラフト率が８００を越えない範囲で吐出開口部の外径と引取り速度を決定することで、通常の繊度を有する複合繊維はもとより、特に０．６〜３．３ｄｔｅｘの範囲にある細繊維をも安定して紡出することが可能となる。なお、紡糸ドラフト率が高すぎる場合、例えば紡糸ドラフト率が８００を越えると紡糸性が悪くなる。また上述の紡糸口金構造をとすることで、吐出線速度の下限を３．５ｃｍ／秒と小さくしても安定した紡糸が可能となる。このため、吐出線速度の変動により引き起こされる、繊維の太さ斑の発生を適宜制御することができると同時に、糸切れ等のトラブルを効果的に防止することができる。
【００３２】
更に本発明にあっては、ポリエステルＡが、第三成分を５〜１５モル％を共重合させた共重合ポリエチレンテレフタレートであることが好ましい。高収縮成分を高粘度側成分とすることで、得られる複合繊維の捲縮発現力をさらに向上させることが可能になる。共重合成分が５モル％未満の場合には、捲縮発現力が不十分であり、１５モル％を越える場合には、得られる共重合ポリエステルＡの融点が低下し、ポリエステルＢとの融点温度差が拡大し、溶融複合紡糸の際、共重合ポリエステルＡの溶融粘度が低下し、ポリエステルＢとの溶融粘度差が確保できなくなるばかりか逆転することにもなり捲縮発現力が不十分となる。
【００３３】
本発明における高粘度ポリエステルＡにおける第三成分としては、テレフタル酸成分以外の芳香族ジカルボン酸類、脂肪族ジカルボン酸類、脂肪族ジオール類、脂環式ジオール類、芳香族ジオール類を用いることができ、具体的にはイソフタル酸、アジピン酸、セバシン酸、１，４−ブタンジオール、シクロヘキサンジオール、ビスフェノールＡのエチレンオキシド付加物等を単独で、または２種以上を組み合わせて用いることができる。好ましい第三成分としては、イソフタル酸（ＩＰＡ）、アジピン酸（ＡＤＥ）、スルホイソフタル酸金属塩（ＤＭＳ）、２，２−ビス［４−（２−ヒドロキシエトキシ）フェニル］プロパン（ＢＰＥ）が挙げられる。これらの第三成分は単独或いは２種以上の組み合わせであってもよい。なお、本発明で用いる共重合率は、２種以上の共重合成分を使用する場合には、合計の共重合率である。
【００３４】
本発明において、共重合ポリエステルＡとポリエステルＢの固有粘度はＡの方が高く、その差は０．１４５より大きくすることが必要である。ここで、固有粘度とは、ポリエステルをフェノールとテトラクロロエタンの１：１混合溶媒に溶解し、ウベローデ粘度計を使用して２５℃で測定した値をいう。固有粘度の差が０．１４５以上の場合には十分な捲縮発現力が得られず、織物に使用したとき必要とする伸縮性が得られない。一方、このように大きな粘度差を有するポリエステル２成分の複合流を紡出する場合には、大きなニーリングが発生しやすい。ニーリングを防止する手段としては、複合流の溶融粘度を低くして高粘度側の表面張力を低下することと吐出線速度を通常用いられる速度よりも小さくすることが有効であるとされている。前者については、複合流の固有粘度を０．５９０以下とすれば、前記したポリエステルＡ及びＢの両成分の固有粘度差が０．１４５より大きくても紡糸が可能となるため好ましい。また、上述の構造をもつ紡糸口金を採用することにより、従来では不可能であった、吐出線速度を３．５ｍ／分と高くしても、上記細繊度の繊維を安定して紡糸することができるようになる。
【００３５】
また、本発明の潜在捲縮性複合繊維を構成する２種類のポリエステルＡ，Ｂの複合比率、すなわち、Ａ成分／Ｂ成分の接合時の重量比率が４／６より大きく６／４より小さいことが好ましく、この範囲を外れる場合には、捲縮発現力が不足した複合繊維となる。高粘度ポリエステル（Ａ）と低粘度ポリエステル（Ｂ）との固有粘度差が０．１４５以下では、複合繊維の形態下での捲縮発現力が不十分であり、織編物としたときに十分な伸縮性を得ることができなくなる。ここで、固有粘度とは、ポリエステルをフェノールとテトラクロロエタンの１：１の混合溶媒に溶解し、ウベローデ粘度計を用いて２５℃で測定した値をいう。
【００３６】
低粘度ポリエステル（Ｂ）は、実質的にエチレンテレフタレート単位のみよりなるポリエステルであり、ポリエチレンテレフタレートが具体的に挙げられるが、第三成分が５モル％未満共重合されたポリエチレンテレフタレートであってもよい。
こうして製造された複合マルチフィラメント繊維を使って得られる織編物は、柔軟で且つストレッチ性に優れ、風合いにも優れたものとなる。
【００３７】
【発明の実施形態】
先ず、本発明に係る複合マルチフィラメント繊維用の紡糸口金について、図面を参照しながら具体的に説明する。図１は、本発明の単繊維の繊度が０．６〜３．３ｄｔｅｘであるポリエステル複合細繊維を紡糸するに適した紡糸口金の構造例を示す断面図である。
【００３８】
本発明によるポリエステル複合マルチフィラメント繊維の紡糸口金は、２種類の溶融粘度の異なるポリエステルが面対称に合流する複数個の吐出孔を備えている。本発明にあって特徴とする点は、前記吐出孔のが任意の断面形状を有すると共に、その断面積が上流側から下流側へ向けて不連続に漸増する吐出開口部と、同吐出開口部の上流側に連設され、２種類のポリエステルが複合される均一な径の細管部とを備えており、前記吐出開口部がその中心軸と壁面とのなす漸増角度θを不連続とすることにある。
【００３９】
細管部を通って複合化された２種類のポリエステルは細管部と吐出開口部との境界にて低粘度側のポリエステルＢ側が凹んで湾曲する、いわゆるニーリングが発生する。このニーリングは吐出開口端に向けて更に曲がろうとする。本発明のごとく、吐出開口部の中心軸と壁面とのなす漸増角度θを不連続、すなわち複数段で漸次大きくすると、細管部と吐出開口部との境界を越えた複合樹脂は第１段目の漸増角度θ１をもつ領域が従来よりも短く、同時に第２断面では漸増角度θ２がθ１よりも大きいため、第１段目における接触時間が少なく且つ第２段目で更なる曲がりが許容されるようになる。その結果、ニーリングの発生を容認しつつ、接触する周辺開口壁面による影響が少なくなり、糸切れが発生せず安定した紡糸が可能となる。この漸増段は少なくとも２段以上であることが望ましい。
【００４０】
これを図１に示す実施例により具体的に説明すると、紡糸口金１０は円盤状ブロック面に３６個の紡糸孔１１が形成されており、各紡糸孔１１は逆円錐台領域１２ａ、円筒領域１２ｂ及び逆三角錐領域１２ｃからなる合流部１２と、前記逆三角錐領域１２ｃの下端開口に続く均一径の細管部１３と、同細管部１３の下端に続き吐出開口端に向けて開口面積を２段以上に段階的に漸増する吐出開口部１４とを有している。同合流部１２は２種類のポリマーが独立して供給される２つの図示せぬ供給路と連通している。
【００４１】
前記紡糸口金１０を使って、溶融粘度差のある２種類のポリエステルを複合したマルチフィラメント繊維を安定して紡糸するには、前記細管部１３の寸法形態が重要な役割を果たす。本発明では、その細管部１３の口径Ｄ１を０．４ｍｍより小さくして、細管部１３の長さＬ１と前記口径Ｄ１との比（Ｌ１／Ｄ１）の値を１．５〜５．５の範囲としている。前記細管部の長さＬと内径Ｄとの比（Ｌ／Ｄ）が１．５より小さいと十分な圧力損失がなされず、ニーリング現象が初期に発生し、繊維の太さ斑が大きくなるだけでなく、糸切断が多くなり、安定して製糸ができなくなる。Ｌ／Ｄの値が５．０を越えると、ＬがＤに比較して相対的に長くなり、紡糸口金の肉厚を一定としたとき、吐出開口端の径を所望の大きさにしようとすれば、吐出開口部の長さを更に長くせざるを得なくなる。
【００４２】
因みに、後述する実施例に使われる紡糸口金１０では、その細管部１３の径Ｄ１を０．３ｍｍとして、細管部１３の長さＬ１を１．２ｍｍ及び１．３ｍｍとして、Ｌ１／Ｄ１の値を、それぞれ４．０及び４．３３に設定している。一方、吐出開口部１４の開口端の径を０．７ｍｍに設定しており、この吐出開口部１４の第１段目の漸増角度θ１を１５°、第２段目の漸増角度θ２を２０°と３０°との２種類としている。
【００４３】
なお、本実施例では前記吐出開口部１４の断面形状を円形としているが、この形状に限定されるものではなく、断面を星型、多角形等、多様な所望形状に形成することもできる。なお、その場合にも断面積を上流側から下流側へ向けて段階的に漸増させることが必要である。
【００４４】
上述の紡糸孔１１を備えた紡糸口金１０を用いて２種類のポリマーを溶融紡糸した場合、前記紡糸孔１１の合流部１２に供給された２種類のポリマーは、前記細管部３において充分に圧力損失がなされ、同吐出孔１１内における２種類の溶融ポリマーの均一分配が可能となる。更に、吐出開口部１４はその径が多段に漸増する形状を有し、その漸増角度θ１，θ２，…を上述のような値に設定することにより、前記吐出開口部１４の下流端でのポリマーの付着を従来に比べ、大幅に削減することができる。
【００４５】
次に、本発明の上記紡糸口金を用いたポリエステルによる高捲縮性の複合マルチフィラメント繊維の製造方法について、実施例を比較例とともに具体的に説明する。
なお、実施例における特性値の評価は次の方法に拠った。
〔糸全体としての太さ斑の変動係数（Ｕ％）〕
計測器工業（株）製の「糸斑試験機ＫＥＴ８０Ｃ」を用い、糸速１５ｍ／分、レンジ±１２．５％、１／２イナートモードの条件で５分以上糸の太さの変動係数（Ｕ％）を測定した。更に、最大Ｕ％値と最小Ｕ％値の差を（△Ｕ％）で表した。
【００４６】
〔未延伸糸の太さ斑の変動係数（Ｕ％）〕
計測器工業（株）「製糸斑試験機ＫＥＴ８０Ｃ」を用い、糸速２００ｍ／分、レンジ±１２．５％、１／２イナートモードの条件で５分以上糸の太さの変動係数Ｕ％を測定した。
【００４７】
〔捲縮率ＣＣ〕
サンプル原糸を枠周１ｍで巻き数１０回の綛を作成し、綛が乱れないように２ヶ所を束ねてくくり、８の字状にして２つ折に重ねて輪にすることを２回繰り返し、ガーゼに包み水浴に浸したときに浮かないように金網箱に入れ、９０℃に調整した恒温槽に２０分間浸漬する。恒温槽から金網箱を取り出し、水を切り綛が乱れない様にろ紙の上に並べる。２０時間以上放置し、自然乾燥した後に捲縮を引き伸ばさないように注意しながら、余分な絡まりをほぐす。表示デシテックス（１．１ｄｔｅｘ）当り４９／２５０００ｃＮ×２０の初荷重をかけ、１分後の長さ（Ｌ３）を測る。初荷重を除重後に表示デシテックス当りの４９／５００ｃＮ×２０の測定荷重を掛けて１分後の長さ（Ｌ４）を測り、除重後２分間放置して再び初荷重を掛けて１分後の長さ（Ｌ５）を測る。
捲縮率ＣＣは、
捲縮率ＣＣ（％）＝｛（Ｌ４−Ｌ５）／Ｌ４｝×１００
により算出する。
【００４８】
〔固有粘度（［η］）〕
ポリエステルをフェノールとテトラクロロエタンの１：１の混合溶媒に溶解し、ウベローデ粘度計を用いて２５℃で測定した。
【００４９】
〔製糸安定性〕
ニ−リング現象の程度を評価した。
良好：ニーリング現象は発生するが、少なくとも２４時間毎の紡糸口金の洗浄を実施することで、安定製糸が可能。
不良：ニーリング現象がひどく、紡出糸がノズル面に付着し、糸切れが多発し、あるいは製糸が不可能。
【００５０】
〔延伸糸伸度〕
島津製作所（株）製オートグラフシステムＳＤ−１００−Ｃを用い、サンプル長２０ｃｍ、引張速度２０ｍ／分の条件で測定した。
【００５１】
（実施例１）
イソフタル酸（ＩＰＡ）８モル％をポリエチレンテレフタレートに共重合した［η］０．６４７の共重合ポリエチレンテレフタレートを高粘度ポリエステル（Ａ）、［η］０．４８４のポリエチレンテレフタレートを低粘度ポリエステル（Ｂ）とし、紡糸温度を２９０℃とし、紡糸吐出孔の上流で２種のポリエステル流を面対称に合流させ、吐出量１０．３２（ｇ／分）×２の接合比（重量比）５／５で、細管部の長さＬ１を１．２ｍｍ、その径Ｄ１を０．３ｍｍ、吐出開口部の長さＬ２を０．４、その開口端の径Ｄ２を０．７ｍｍとした３６個の紡糸孔を有する複合紡糸口金より紡出した。
【００５２】
複合紡糸口金の吐出開口部の漸増角度を２段とし、１段目の漸増角度θ１を１５°、２段目（開口端部）の漸増角度θ２を２０°とし、前記紡出糸条を冷却、オイリング後、２１００ｍ／分の引取速度で巻き取り、９５ｄｔｅｘ／３６フィラメントの複合繊維の未延伸糸を得た。このときの吐出線速度は６．７ｍ／ｍｉｎであり、ドラフト率は１７１９とした。得られた未延伸糸を表１に示す条件で延伸して５６ｄｔｅｘ／３６フィラメントのポリエステル複合マルチフィラメント繊維の延伸糸を得た。
【００５３】
その結果を、表１に示す。同表から未延伸糸の太さ斑の変動計数（Ｕ％）は０．７５％、延伸糸の太さ斑の変動計数（Ｕ％）は０．４５、延伸糸の最大Ｕ％値と最小Ｕ％値の差（ΔＵ％）は０．８０％、延伸糸の単繊維繊度は５６／３６ｆ（ｄｔｅｘ）、延伸糸の捲縮（ＣＣ）は３２であって、紡糸口金の洗浄を行うことなく４２時間安定した延伸ができた。
【００５４】
（実施例２）
細管部の長さＬ１を１．３ｍｍ、吐出開口部の長さＬ２を０．３ｍｍ、２段目の漸増角度θ２を２０°とした以外は、実施例１と同様の複合紡糸口金を用いるとともに、紡糸条件も実施例１と同様とした。
【００５５】
その結果を、表１に示す。同表から未延伸糸の太さ斑の変動計数（Ｕ％）は０．７５％、延伸糸の太さ斑の変動計数（Ｕ％）は０．４５、延伸糸の最大Ｕ％（Ｍ）値と最小Ｕ％（Ｍ）値の差を（ΔＵ％）は０．８０％、延伸糸の単繊維繊度は５６／３６ｆ（ｄｔｅｘ）、延伸糸の捲縮（ＣＣ）は３４であって、実施例１同様に紡糸口金の洗浄を行うことなく４２時間安定した延伸ができた。
【００５６】
（比較例１）
細管部の長さＬ１を１．５ｍｍ、吐出開口部の長さＬ２を０ｍｍ、同開口端の径Ｄ２を０．５ｍｍ、前記開口端の漸増角度θを１段１５°とした以外は実施例１と同様の構造を有する複合紡糸口金を使い、紡糸条件としてドラフト率を８７７とした以外は実施例１と同様の紡糸条件で紡糸し、実施例１と同じ繊度のポリエステル複合マルチフィラメント繊維の延伸糸を得た。
【００５７】
その結果を、表１に示す。同表から未延伸糸の太さ斑の変動計数（Ｕ％）は０．７０％、延伸糸の太さ斑の変動計数（Ｕ％）は０．４、延伸糸の最大Ｕ％値と最小Ｕ％値の差（ΔＵ％）は０．５０％、延伸糸の捲縮（ＣＣ）は３５であったが、紡糸口金の洗浄を行っても２４時間安定した延伸ができなかった。
【００５８】
（比較例２）
細管部の長さＬ１を１．５ｍｍ、その径Ｄ１を０．４ｍｍ、吐出開口部の長さＬ２を０ｍｍ、その開口端の径を０．５ｍｍとし、吐出開口部の漸増角度を１５°１段とした複合紡糸口金を用い、紡糸条件として吐出線速度を３．７ｍ／ｍｉｎ、ドラフト率８７７とした以外は実施例１と同様の紡糸条件で、実施例１と同じ繊度のポリエステル複合マルチフィラメント繊維の延伸糸を得た。
【００５９】
その結果を、表１に示す。同表から未延伸糸の太さ斑の変動計数（Ｕ％）は１．００％、延伸糸の太さ斑の変動計数（Ｕ％）は０．６、延伸糸の最大Ｕ％値と最小Ｕ％値の差（ΔＵ％）は２．５０％、延伸糸の捲縮（ＣＣ）は３５であり、紡糸口金の洗浄を行っても糸切れが多く安定した延伸ができなかった。
【００６０】
（比較例３）
細管部の長さＬ１を１．５ｍｍ、その径Ｄ１を０．５ｍｍ、吐出開口部の長さＬ２を０ｍｍ、その開口端の漸増角度θを１段１５°とした以外は実施例１と同様の構造を有する複合紡糸口金を用い、紡糸条件として吐出線速度を２．４ｍ／ｍｉｎとした以外は実施例１と同様の紡糸条件で、実施例１と同じ繊度のポリエステル複合マルチフィラメント繊維の延伸糸を得た。
【００６１】
その結果を、表１に示す。同表から、紡糸口金の洗浄を行うかぎり２４時間の安定した延伸ができ、延伸糸の捲縮（ＣＣ）も３６と多く捲縮性は高かったが、未延伸糸の太さ斑の変動計数（Ｕ％）は１．４０％、延伸糸の太さ斑の変動計数（Ｕ％）は測定が不能なほど斑が多く、延伸糸の最大Ｕ％値と最小Ｕ％値の差（ΔＵ％）も３．００％と極めて多く、均等な染色が期待できるものではなかった。
【００６２】
（比較例４）
細管部の長さＬ１を１．４ｍｍ、吐出開口部の長さＬ２を０．２ｍｍ、その開口端側の２段目の漸増角度θ２を５０°とした以外は実施例１と同様の構造を有する複合紡糸口金を用い、紡糸条件として吐出線速度を２．４ｍ／ｍｉｎとした以外は実施例１と同様の紡糸条件で、実施例１と同じ繊度のポリエステル複合マルチフィラメント繊維の延伸糸を得た。その結果は、表１に示すとおり、紡糸口金からの吐出が安定せず、巻き取りが不可能であった。
【００６３】
【表１】

【００６４】
以上の説明によっても明らかなように、本発明の潜在捲縮性ポリエステル複合マルチフィラメント繊維の製造時に使われる複合紡糸口金の吐出孔を細管部と出口に向けて複数段で漸増角度が変わる吐出開口部とにより構成しているため、この紡糸口金を用いて、所定の紡糸条件を満足させることにより、従来では吐出線速度の変動により引き起こされる、繊維の太さ斑の発生、糸切れ等のトラブルを効果的に防止することができるようになった。
【００６５】
その結果、高い潜在捲縮性を有し十分なふくらみ感とストレッチ性を有する通常の繊度を有する複合繊維を安定して紡糸できるのは当然のこととして、従来では連続して安定紡糸をすることが不可能とされていた、特に高い潜在捲縮性を有し十分なふくらみ感とストレッチ性を有する細繊度の複合繊維を安定して紡糸することが可能となり、それらの繊維を使うことにより、弾力性とふっくら感に富むとともに柔軟性に優れ、しかもストレッチ性が高い織編物が得られる。
【図面の簡単な説明】
【図１】本発明に係る溶融紡糸口金の１態様を要部で示す縦断面図である。
【符号の説明】
１０紡糸口金
１１吐出孔
１２合流部
１３細管部
１４吐出開口部
Ｌ１細管部の長さ
Ｌ２吐出開口部の長さ
Ｄ１細管部の径
Ｄ２吐出開口部の開口端径
θ， θ１， θ２吐出開口部の漸増角度[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spinneret for a latently crimped high stretch conjugate fiber used for woven or knitted fabrics for clothing use, interior use, and the like, a method for producing a composite multifilament fiber using the spinneret, and a fine fiber obtained by the production method. The present invention relates to a fiber and a woven or knitted fabric using the fiber.
[0002]
[Prior art]
Conventionally, it has been known that two types of thermoplastic polyesters having different melt viscosities are spun out from the same spouting hole to form a joint type composite fiber yarn by a composite spinning, and a heat treatment to develop a spiral crimp and a crimped stretch yarn. In order to obtain a high crimp, it is necessary to increase the difference in melt viscosity between the two types of thermoplastic polyesters used. For example, in JP-A-3-69647, it is possible to use a polyester having high melt viscosity as a high melt viscosity component. Are known. However, when two types of polyesters having different melt viscosities are laminated and spun, the spun yarn may bend to a high viscosity component side due to a difference in the ballast effect of both polyesters (bending phenomenon). Are known. The greater the difference in melt viscosity between the two components during spinning of the joined composite stream, the greater the kneeling phenomenon and the worse the spinnability. For this reason, it is difficult to stably produce a latently crimped stretch fiber that can provide sufficient swelling and stretchability in a woven or knitted fabric, particularly a woven fabric.
[0003]
Japanese Patent Application Laid-Open No. 8-302518 proposes a spinneret in which two kinds of polymer streams are respectively discharged, and after the discharge, they merge to avoid a kneeling phenomenon. However, in such a spinneret, the production accuracy of the discharge hole greatly affects the formation of the composite stream, and it is difficult to secure a stable spinning state. Moreover, since it becomes an expensive spinneret, it is difficult to employ industrially.
[0004]
On the other hand, as one of means for expressing a multi-color of a fiber product, a fine fiber giving a marbling effect is known, and this thick fiber is obtained by drawing an undrawn yarn having a relatively low degree of orientation at a low magnification. In order to obtain a stretchable woven or knitted fabric having a marbling-like appearance, a method of forming a woven or knitted fabric by using a mixed fiber consisting of thick fibers giving a marbling effect and fibers giving elasticity is known. However, in order to obtain such a mixed fiber, not only the process is complicated and the cost is increased, but also the handling of temperature change, control and the like at the time of dyeing due to the difference in dyeability between the two types of mixed fibers. Problems also arise.
[0005]
A spinneret suitable for solving these problems and stably spinning a latently crimped high stretch conjugate fiber used for woven or knitted fabrics for clothing use, interior use, etc. is disclosed in, for example, JP-A-11-36148. And JP-A-11-107050, JP-A-11-200155, and JP-A-2000-160443.
[0006]
In particular, according to Japanese Patent Application Laid-Open No. H11-107050, which defines the specific configuration of the spinneret, the spinneret has an arbitrary cross-sectional shape, and has a truncated polygonal pyramid shape whose cross-sectional area gradually increases from the upstream side to the downstream side. A discharge opening portion, and a narrow tube portion of a uniform diameter, which is connected to the upstream side of the discharge opening portion and in which two types of polyesters are combined, wherein the discharge opening portion has a gradually increasing angle θ between the central axis and the wall surface. Has been proposed from 10 ° to 25 °.
[0007]
When the polyester A and the polyester B are used to produce a bonded composite fiber by a composite spinning method, in general, when a two-component polyester having different melting properties is melt-spun as a bonded composite stream, kneeling occurs. It reduces the spinning stability. For this reason, in the above-mentioned publication, stable spinning is realized by reducing the discharge linear velocity when spinning the combined-type composite stream.
[0008]
In order to reduce the discharge linear velocity, it is effective to increase the discharge hole area of the spinneret, and the discharge holes necessary for stably spinning the composite flow of polyester A and polyester B of the present invention. The diameter of the opening is set so that the discharge linear velocity of the composite flow is 14 cm / sec or less. However, if the diameter of the discharge hole is simply increased for the purpose of reducing the discharge linear velocity, the pressure loss of the spinneret becomes small, and the distribution of the molten polyester to each discharge hole for forming a multifilament is uneven. It becomes. Furthermore, the discharge pressure is extremely reduced, causing fluctuations in the discharge linear velocity. As a result, pulsation occurs in the yarn length direction, causing unevenness in the thickness of the fiber, and the draft rate increases, resulting in yarn breakage. Problems occur.
[0009]
If the gradually increasing angle θ is less than 10 °, the discharge opening must be extended until the discharge opening at the lower end of the discharge opening has a predetermined diameter, and the length dimension increases, There is a disadvantage that the spinneret becomes large and the production cost increases. If the angle θ is greater than 25 °, the pressure change at the discharge opening becomes large, and the yarn breakage is likely to occur.
[0010]
As described above, since the narrow tube portion is provided in each of the discharge holes of the spinneret, a sufficient pressure loss can be obtained to enable uniform distribution of the molten polyester between the discharge holes. Further, the discharge opening formed continuously with the thin tube portion has a shape in which the sectional area gradually increases from the upstream side to the downstream side, and the gradually increasing angle θ is set to 10 ° to 25 °. By setting the outer diameter of the discharge opening of the spinneret and the take-up speed within a range where the spinning draft rate does not exceed 800, a stable spinning state is ensured.
[0011]
[Patent Document 1]
JP-A-3-69647
[Patent Document 2]
JP-A-8-302518
[Patent Document 3]
JP-A-11-36148
[Patent Document 4]
JP-A-11-107050
[Patent Document 5]
JP-A-11-200155
[Patent Document 6]
JP-A-2000-160443
[0012]
[Problems to be solved by the invention]
However, the size of the discharge hole of such a spinneret greatly affects the formation of a composite stream. Particularly, in a spinneret that stably spins fine fibers, the shape of the discharge hole, in addition to the size thereof, greatly affects the formation of the composite flow, and the spinning stability is impaired. That is, as described in Patent Literature 4, simply forming the shape into a truncated polygonal pyramid often causes the fiber to be cut by kneeling that occurs at the boundary between the thin tube portion and the discharge hole of the truncated polygonal pyramid. The occurrence of this kneeling cannot be solved simply by manufacturing the ejection holes with high precision. Further, when used, polyester or the like may adhere to the opening end of the discharge hole to cause a slight deviation in its size. In this case, it is difficult to secure a stable spinning state, and frequent cleaning is performed. The task of having to do so also remains.
[0013]
That is, the present invention provides a spinneret capable of stably producing a conjugated polyester fiber by an industrially simple production process, and particularly provides a spinneret capable of stably obtaining the fine fiber, and an effective method for producing the same. . It also provides a latently crimped composite polyester fine fiber having sufficient swelling and stretchability as a woven / knitted fabric and capable of obtaining uniform dyeing, and a woven / knitted fabric using the same.
[0014]
Means for Solving the Problems and Functions and Effects
Therefore, the present invention is a spinneret for melt-spinning a joint type latently crimped conjugate polyester fiber in which two types of polyesters are independently supplied, and the two are joined and discharged, and has an arbitrary cross-sectional shape. A discharge opening having a cross-sectional area that gradually increases from the upstream side to the downstream side, and a narrow-tube portion having a uniform diameter in which two types of polyester are combined and connected to the upstream side of the discharge opening. The main constitution of the spinneret for polyester composite multifilament fiber is that the gradually increasing angle θ between the central axis and the wall surface of the discharge opening is discontinuous.
[0015]
That is, in the present invention, the discharge opening is not simply formed in a truncated polygonal shape as in Patent Document 5, but the gradually increasing angle θ of the discharge opening is discontinuously increased. In other words, the opening angle (gradual increase angle) θ expanding toward the discharge opening end of the discharge opening is changed so as to gradually and gradually increase. As a result, it becomes possible to instantaneously cut off the contact with the discharge opening due to the bending of the fiber due to the kneeling phenomenon occurring at the boundary between the thin tube portion and the discharge opening, and at the same time tolerate further bending. Even with fine fibers, yarn breakage can be greatly reduced, and spinning stability can be ensured. Further, even in the present invention, as described above, since the narrow tube portion is provided in each of the discharge holes of the spinneret, a sufficient pressure is required to enable uniform distribution of the molten polyester between the discharge holes. Loss can be obtained.
[0016]
It is desirable that the gradually increasing angle θ between the central axis of the discharge opening and the wall surface is discontinuously increased within a range of 10 ° to 45 °. For example, the first-stage incremental angle θ1 at the boundary between the thin tube portion and the discharge opening is set in the range of 10 ° to 20 ° as in Patent Document 4, and the second-stage incremental angle θ2 is set. Spread from 20 ° to 45 °. As a result, in addition to the above-described functions, ease of processing and ease of maintenance such as cleaning are ensured. In this case, the inner diameter D1 of the thin tube portion is 0.4 mm or less, the ratio (L / D) of the length L1 of the thin tube portion to the inner diameter D1 is 1.5 to 5.0, and the diameter of the discharge opening is It is more preferable that D2 is a discharge hole of 0.5 mm or more.
[0017]
When the gradually increasing angle θ is less than 10 °, the discharge opening must be extended until the discharge opening at the lower end of the discharge opening has a predetermined diameter, and the length dimension is increased. In addition, disadvantages such as an increase in the size of the spinneret and an increase in manufacturing cost occur. Further, when the taper angle is larger than 25 °, the pressure change in the orifice becomes large and not only yarn breakage occurs but also affects the quality. However, according to the spinneret of the present invention, the gradually increasing angle of the final stage is obtained. Up to 45 °, the pressure change at the discharge opening is stable, there is almost no occurrence of thread breakage, and stable spinning is possible.
[0018]
When the inner diameter D1 of the thin tube portion exceeds 0.4 mm, kneeling is severe and thread breakage occurs frequently. Pressure loss cannot be obtained, and a kneeling phenomenon occurs at an early stage, and not only unevenness of fiber thickness is increased, but also thread breakage increases, and stable yarn cannot be produced. If the value of L / D exceeds 5.0, L becomes relatively long compared to D, and when the thickness of the spinneret is constant, the discharge opening end may have a desired large diameter. In addition, the length of the discharge opening must be further increased. The diameter of the discharge opening end is preferably 0.5 mm or more.
[0019]
A second basic configuration of the present invention is a joint type latent winding of two types of high-viscosity polyester A and low-viscosity polyester B having different melt viscosities using a spinneret having a structure unique to the present invention described above. The present invention relates to a method for producing a reduced polyester composite multifilament fiber. The high-viscosity polyester A and the low-viscosity polyester B need to satisfy the following formulas (1) and (2). In the method for producing a composite multifilament fiber according to the present invention, a composite stream of a high-viscosity polyester (A) and a low-viscosity polyester (B) is provided upstream of the spinneret, and a linear drawing speed of 3.5 m / min or more and a spinning draft 800 As described above, the variation coefficient U% (L) of the unevenness in the thickness of the undrawn yarn fibers is discharged from the discharge opening to 0.8% or less.
[0020]
4/6 ≦ W ≦ 6/4 (1)
[Η] A- [η] B> 0.145 (2)
In the formula, [η] A and [η] B represent the intrinsic viscosities of A and B, respectively, and W represents the junction ratio (weight ratio) of A / B.
[0021]
As the polyester A, a dicarboxylic acid component containing 88 to 98 mol% of a terephthalic acid component and 2 to 12 mol% of an aliphatic dicarboxylic acid component having 4 to 12 carbon atoms, 1,4-butanediol and an average molecular weight of 400 to 4000 And a diol component mainly composed of polytetramethylene glycol, wherein the polytetramethylene glycol is contained in an amount of 15 to 35% by weight based on the total amount of the polyester A, and employs a copolymer having a melting point of 180 ° C. or more. As the polyester B, a polymer substantially consisting of tetramethylene terephthalate units and having a melting point of 210 ° C. to 230 ° C. is adopted, and the weight ratio between the polyester A and the polyester B is 6/4 to 4/6. Set and make a composite stream upstream of the spinneret, and discharge linear velocity of the composite stream is 14 cm / sec or less. Are the main components also the manufacturing method of the potential crimping composite polyester fiber characterized by comprising, be ejected from the discharge opening.
[0022]
Since the aliphatic dicarboxylic acid component is contained in the dicarboxylic acid component of the polyester A, the composite polyester fiber finally obtained by combining the polyester A and the polyester B has improved crystallization characteristics and crimping. The expression performance is also improved. Further, when melt-spinning the conjugate fiber, the chips adhere to each other even when the dried chips of the polyester A containing the aliphatic dicarboxylic acid component are supplied to a spinning machine, or the chips adhere to the container wall surface. Such a problem does not occur, and the handleability of the polyester chip is improved. In addition, it exhibits sufficient swelling and stretchability as a woven or knitted fabric. . Furthermore, the composite fiber using the copolymerized polyester as one side component can be easily and stably melt-shaped by a general thermoplastic polymer melt spinning step.
[0023]
The aliphatic dicarboxylic acid contained in the polyester A is preferably copolymerized in an amount of from 2 to 12 mol% based on all dicarboxylic acid components. When the copolymerization amount of the aliphatic dicarboxylic acid in all the dicarboxylic acid components is less than 2 mol%, the effect of improving the crystallization properties and crimping performance of the composite polyester fiber obtained by combining the polyester A and the polyester B are obtained. Is insufficient. On the other hand, when the copolymerization amount of the aliphatic dicarboxylic acid in all the dicarboxylic acid components exceeds 12 mol%, the crystallinity of the polyester A gradually decreases, and the crimping performance of the composite fiber of the polyester A and the polyester B further increases. Not only is the improvement effect of the polyester A not expected, but also the handleability of the polyester A chip is reduced.
[0024]
As the dicarboxylic acid component of the polyester A, a small amount of a dicarboxylic acid component other than the terephthalic acid component and the aliphatic dicarboxylic acid may be used in a range that does not impair the object of the present invention. However, in this case, it is necessary that the melting point of the polyester A is 180 ° C. or higher. When the melting point of the polyester A is lower than 180 ° C., the thermal stability of the polyester A is lowered, and further, the process stability at the time of melt spinning the polyester A with the polyester B is not preferable.
[0025]
Other dicarboxylic acid components other than the terephthalic acid component and the aliphatic dicarboxylic acid include isophthalic acid, 5-sulfoisophthalic acid or 2-sulfoisophthalic acid, alkali metal salts such as 1,8-dicarboxynaphthalene-3-sulfonic acid, Dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, or ester-forming derivatives thereof, p-oxybenzoic acid, p-β-oxy Oxycarboxylic acids such as ethoxybenzoic acid, or ester-forming derivatives thereof, 5-tetrabutylphosphonium sulfoisophthalic acid, 5-tetraphenylphosphonium sulfoisophthalic acid, 5-phenyltributylphosphonium sulfoisophthalic acid, 5-butyltol Phosphonium sulfonate-containing dicarboxylic acids such as tetraphenylphosphonium sulfoisophthalic acid, or the like ester-forming derivatives thereof and the like.
[0026]
As the diol component of the polyester A, 1,4-butanediol and polytetramethylene glycol are used as main components. The use of 1,4-butanediol as the diol component of the polyester A not only improves the crystallization rate of the polyester A but also reduces the crimp development characteristics of the composite fiber finally obtained from the polyester A and the polyester B. It is to improve. Furthermore, when 1,4-butanediol is included as a diol component, the handleability of polyester A chips is improved. In addition, when other diol components such as ethylene glycol are used as a main component instead of the above-mentioned diol components, the crystallization speed of the polyester is not sufficient, and as a result, crystal formation of the polyester becomes insufficient, Not only does the handling of the chips deteriorate, but also the crimping characteristics of the conjugate fiber obtained by conjugate spinning with the polyester B become insufficient.
[0027]
As the polytetramethylene glycol contained in the polyester A, those having an average molecular weight of 400 to 4000 can be employed, and those having an average molecular weight of 800 to 3000 are particularly preferable. Polyester containing polytetramethylene glycol having an average molecular weight of less than 400, when the polyester is composite-spun with polyester B as one side component, the resulting composite fiber does not have sufficient crimp development performance, Further, when polytetramethylene glycol having an average molecular weight exceeding 4000 is contained, it is difficult to obtain a uniform polyester, and the composite fiber obtained by composite-spinning such a polyester with polyester B as one side component is not used. The shrinkage expression performance is low.
[0028]
In the present invention, as the polytetramethylene glycol contained in the polyester A, a plurality of types of polytetramethylene glycols having different average molecular weights can be mixed and used as long as the average molecular weight is in the range of 400 to 4000.
[0029]
When spinning using the above spinneret while compounding these polyester A and polyester B, an appropriate inner diameter of the discharge opening end of the spinneret and a take-up speed are set so that the spinning draft rate does not exceed 800. Thus, a stable spinning state can be secured. This spinning draft rate is appropriately determined by the opening diameter of the discharge opening end and the take-up speed.
[0030]
Polyester A and polyester B can be used to produce a conjugated composite fiber by a composite spinning method. In general, when a two-component polyester having different melting properties is melt-spun as a conjugated composite stream. In this case, kneeling occurs and the yarn production stability decreases. Therefore, in the production method of the present invention, it is necessary to reduce the discharge linear velocity at the time of spinning the bonded composite stream in order to realize stable yarn production.
[0031]
In the present invention, as a countermeasure for these, a narrow tube portion is obtained in the discharge hole where a sufficient pressure loss is obtained to enable uniform distribution of the molten polyester between the respective discharge holes, and the narrow tube portion is directed toward the discharge opening from the narrow tube portion. A composite fiber having a normal fineness by adopting a discharge opening shape in which the diameter increases discontinuously and determining the outer diameter and the take-up speed of the discharge opening within a range where the spinning draft rate does not exceed 800. In addition, it is possible to stably spin fine fibers, particularly in the range of 0.6 to 3.3 dtex. In addition, when the spinning draft rate is too high, for example, when the spinning draft rate exceeds 800, the spinnability deteriorates. Further, by adopting the spinneret structure described above, stable spinning can be performed even if the lower limit of the ejection linear velocity is reduced to 3.5 cm / sec. For this reason, it is possible to appropriately control the occurrence of unevenness in the fiber thickness caused by the fluctuation of the ejection linear velocity, and it is possible to effectively prevent troubles such as thread breakage.
[0032]
Furthermore, in the present invention, it is preferable that the polyester A is a copolymerized polyethylene terephthalate obtained by copolymerizing 5 to 15 mol% of the third component. By using the high-shrinkage component as the high-viscosity component, it is possible to further improve the crimping ability of the obtained conjugate fiber. When the amount of the copolymer component is less than 5 mol%, the crimp developing power is insufficient, and when the amount exceeds 15 mol%, the melting point of the obtained copolymerized polyester A decreases, The difference increases, and the melt viscosity of the copolyester A decreases during the melt-spinning, and not only the melt viscosity difference from the polyester B cannot be ensured but also reverse, and the crimping ability becomes insufficient. .
[0033]
As the third component in the high-viscosity polyester A of the present invention, aromatic dicarboxylic acids other than the terephthalic acid component, aliphatic dicarboxylic acids, aliphatic diols, alicyclic diols, and aromatic diols can be used. Specifically, isophthalic acid, adipic acid, sebacic acid, 1,4-butanediol, cyclohexanediol, an ethylene oxide adduct of bisphenol A, or the like can be used alone or in combination of two or more. Preferred third components include isophthalic acid (IPA), adipic acid (ADE), metal sulfoisophthalate (DMS), and 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane (BPE). Can be These third components may be used alone or in combination of two or more. In addition, the copolymerization rate used in the present invention is a total copolymerization rate when two or more copolymerization components are used.
[0034]
In the present invention, the intrinsic viscosity of the copolyester A and the polyester B is higher in A, and the difference must be larger than 0.145. Here, the intrinsic viscosity refers to a value obtained by dissolving a polyester in a 1: 1 mixed solvent of phenol and tetrachloroethane and measuring the resultant at 25 ° C. using an Ubbelohde viscometer. When the difference in the intrinsic viscosity is 0.145 or more, sufficient crimping force cannot be obtained, and the required elasticity when used for a woven fabric cannot be obtained. On the other hand, when spinning a composite stream of a two-component polyester having such a large viscosity difference, large kneeling is likely to occur. As means for preventing the kneeling, it is effective to lower the melt viscosity of the composite stream to lower the surface tension on the high viscosity side and to make the discharge linear velocity lower than a commonly used velocity. Regarding the former, it is preferable to set the intrinsic viscosity of the composite stream to 0.590 or less, since spinning becomes possible even if the intrinsic viscosity difference between both components of the polyesters A and B is larger than 0.145. In addition, by employing the spinneret having the above-described structure, even if the ejection linear velocity is increased to 3.5 m / min, which is impossible in the past, it is possible to stably spin the fibers having the above fineness. Will be able to
[0035]
Further, the composite ratio of the two types of polyesters A and B constituting the latently crimpable conjugate fiber of the present invention, that is, the weight ratio at the time of joining the A component / B component is larger than 4/6 and smaller than 6/4. When the ratio is out of this range, a conjugate fiber having insufficient crimp developing power is obtained. If the intrinsic viscosity difference between the high-viscosity polyester (A) and the low-viscosity polyester (B) is 0.145 or less, the crimp development force in the form of a conjugate fiber is insufficient, and the woven or knitted product is insufficient. Elasticity cannot be obtained. Here, the intrinsic viscosity refers to a value obtained by dissolving the polyester in a mixed solvent of phenol and tetrachloroethane at a ratio of 1: 1 and using an Ubbelohde viscometer at 25 ° C.
[0036]
The low-viscosity polyester (B) is a polyester substantially composed of only ethylene terephthalate units, and specific examples thereof include polyethylene terephthalate. However, polyethylene terephthalate in which the third component is copolymerized in less than 5 mol% may be used. .
The woven or knitted fabric obtained by using the composite multifilament fiber produced in this manner has flexibility, excellent stretchability, and excellent texture.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
First, a spinneret for a composite multifilament fiber according to the present invention will be specifically described with reference to the drawings. FIG. 1 is a sectional view showing a structural example of a spinneret suitable for spinning a polyester composite fine fiber having a fineness of a single fiber of 0.6 to 3.3 dtex of the present invention.
[0038]
The spinneret of the polyester composite multifilament fiber according to the present invention is provided with a plurality of discharge holes where two types of polyesters having different melt viscosities merge symmetrically in a plane. The present invention is characterized in that the discharge opening has an arbitrary cross-sectional shape, and the cross-sectional area of the discharge opening is gradually increased from the upstream side to the downstream side; And a narrow tube portion having a uniform diameter, in which two types of polyesters are combined, and the discharge opening portion has a discontinuous increasing angle θ between its central axis and a wall surface. It is in.
[0039]
The so-called kneeling, in which the two types of polyester compounded through the thin tube portion is bent at the boundary between the thin tube portion and the discharge opening, and the low-viscosity polyester B side is depressed and curved. This kneeling tends to bend further towards the end of the discharge opening. As in the present invention, when the gradually increasing angle θ formed by the central axis of the discharge opening and the wall surface is discontinuous, that is, gradually increased in a plurality of stages, the composite resin that exceeds the boundary between the thin tube portion and the discharge opening becomes the first stage. Is smaller than the conventional one, and at the same time, in the second cross section, the gradually increasing angle θ2 is larger than θ1, so that the contact time in the first step is short and further bending is allowed in the second step. Become like As a result, while the occurrence of the kneeling is tolerated, the influence of the peripheral opening wall surface in contact is reduced, and the stable spinning without the yarn breakage is enabled. It is desirable that the number of the gradually increasing stages is at least two or more.
[0040]
This will be described in detail with reference to the embodiment shown in FIG. 1. The spinneret 10 has 36 spinning holes 11 formed on a disk-shaped block surface, and each of the spinning holes 11 has an inverted truncated cone region 12a and a cylindrical region 12b. And a confluent portion 12 composed of an inverted triangular pyramid region 12c; a thin tube portion 13 having a uniform diameter following the lower end opening of the inverted triangular pyramid region 12c; It has a discharge opening 14 that gradually increases in stages or more. The junction 12 communicates with two supply paths (not shown) to which two types of polymers are independently supplied.
[0041]
In order to stably spin a multifilament fiber composed of two types of polyesters having different melt viscosities by using the spinneret 10, the dimension of the thin tube portion 13 plays an important role. In the present invention, the diameter D1 of the thin tube portion 13 is made smaller than 0.4 mm, and the value of the ratio (L1 / D1) between the length L1 of the thin tube portion 13 and the diameter D1 is 1.5 to 5.5. Range. If the ratio (L / D) of the length L to the inside diameter D (L / D) is smaller than 1.5, a sufficient pressure loss is not achieved, a kneeling phenomenon occurs at an early stage, and the thickness unevenness of the fiber increases. In addition, the number of thread cuts increases, and stable yarn production cannot be performed. When the value of L / D exceeds 5.0, L becomes relatively longer than D, and when the thickness of the spinneret is fixed, the diameter of the discharge opening end is made to be a desired size. Then, the length of the discharge opening must be further increased.
[0042]
Incidentally, in the spinneret 10 used in the embodiment described later, the diameter D1 of the thin tube portion 13 is 0.3 mm, the length L1 of the thin tube portion 13 is 1.2 mm and 1.3 mm, and the value of L1 / D1 is , Respectively, are set to 4.0 and 4.33, respectively. On the other hand, the diameter of the opening end of the discharge opening 14 is set to 0.7 mm, and the first stage gradually increasing angle θ1 of the discharge opening 14 is 15 °, and the second stage gradually increasing angle θ2 is 20 °. And 30 °.
[0043]
In this embodiment, the cross-sectional shape of the discharge opening 14 is circular. However, the shape is not limited to this, and the cross-section can be formed into various desired shapes such as a star and a polygon. In this case as well, it is necessary to gradually increase the cross-sectional area stepwise from the upstream side to the downstream side.
[0044]
When two types of polymers are melt-spun using the spinneret 10 having the above-described spinning holes 11, the two types of polymers supplied to the junction 12 of the spinning holes 11 are sufficiently pressured in the thin tube portion 3. Loss is made, and uniform distribution of the two types of molten polymers in the discharge hole 11 becomes possible. Further, the discharge opening 14 has a shape in which the diameter gradually increases in multiple stages, and by setting the gradually increasing angles θ1, θ2,... To the values described above, the polymer at the downstream end of the discharge opening 14 is formed. Can be greatly reduced as compared with the related art.
[0045]
Next, a method for producing a high-crimp composite multifilament fiber using polyester using the above spinneret of the present invention will be specifically described with reference to Examples and Comparative Examples.
The evaluation of the characteristic values in the examples was based on the following method.
[Coefficient of variation of thickness unevenness as a whole yarn (U%)]
Using a "Yet spot tester KET80C" manufactured by Keisoku Kogyo Co., Ltd., the variation coefficient (U) of the yarn thickness is 5 minutes or more under the conditions of a yarn speed of 15 m / min, a range of ± 12.5%, and a 1/2 inert mode. %) Was measured. Further, the difference between the maximum U% value and the minimum U% value was represented by (ΔU%).
[0046]
[Coefficient of variation of thickness variation of undrawn yarn (U%)]
Using a measuring instrument industry “KET80C”, the variation coefficient U% of the thickness of the yarn for 5 minutes or more under the conditions of a yarn speed of 200 m / min, a range of ± 12.5%, and a half inert mode. It was measured.
[0047]
[Crimp ratio CC]
Create a skein of 10 windings around the frame 1m around the frame of the sample, wrap it in two places so that the skein is not disturbed, and make it into a figure eight shape, fold it into two, and repeat twice. Wrapped in gauze, placed in a wire mesh box so as not to float when immersed in a water bath, and immersed in a thermostat adjusted to 90 ° C. for 20 minutes. Take out the wire mesh box from the thermostat, drain the water and arrange it on filter paper so that the skein is not disturbed. Allow to stand for 20 hours or more, and after air-drying, loosen excess entanglement, taking care not to stretch the crimp. An initial load of 49/25000 cN × 20 per indicated decitex (1.1 dtex) is applied, and the length (L3) after 1 minute is measured. After removing the initial load, apply a measurement load of 49/500 cN × 20 per indicated decitex, measure the length (L4) after 1 minute, leave it for 2 minutes after removing the load, apply the initial load again, and after 1 minute Is measured (L5).
The crimp rate CC is
Crimp rate CC (%) = {(L4-L5) / L4} × 100
Is calculated by
[0048]
[Intrinsic viscosity ([η])]
The polyester was dissolved in a 1: 1 mixed solvent of phenol and tetrachloroethane and measured at 25 ° C. using an Ubbelohde viscometer.
[0049]
(Spinning stability)
The degree of the kneeling phenomenon was evaluated.
Good: Although the kneeling phenomenon occurs, stable spinning can be performed by washing the spinneret at least every 24 hours.
Poor: Kneeling phenomenon is severe, spun yarn adheres to the nozzle surface, yarn breakage occurs frequently, or yarn production is impossible.
[0050]
(Drawing yarn elongation)
The measurement was performed using an autograph system SD-100-C manufactured by Shimadzu Corporation under the conditions of a sample length of 20 cm and a tensile speed of 20 m / min.
[0051]
(Example 1)
[Η] 0.647 copolymerized polyethylene terephthalate obtained by copolymerizing 8 mol% of isophthalic acid (IPA) with polyethylene terephthalate is a high viscosity polyester (A), and [η] 0.484 polyethylene terephthalate is a low viscosity polyester (B) At a spinning temperature of 290 ° C., two types of polyester streams are merged in a plane-symmetric manner upstream of the spinning discharge hole, and a discharge rate of 10.32 (g / min) × 2 and a joining ratio (weight ratio) of 5/5 are satisfied. The length L1 of the thin tube portion is 1.2 mm, the diameter D1 is 0.3 mm, the length L2 of the discharge opening is 0.4, and the diameter D2 of the opening end is 36 mm. It was spun from a composite spinneret.
[0052]
The gradual increase angle of the discharge opening of the composite spinneret is set to two stages, the gradual increase angle θ1 of the first stage is set to 15 °, the gradual angle θ2 of the second stage (opening end) is set to 20 °, and the spun yarn is cooled. After oiling, winding was performed at a take-up speed of 2100 m / min to obtain an undrawn yarn of a composite fiber of 95 dtex / 36 filaments. At this time, the discharge linear velocity was 6.7 m / min, and the draft rate was 1,719. The obtained undrawn yarn was drawn under the conditions shown in Table 1 to obtain a drawn yarn of a 56 dtex / 36 filament polyester composite multifilament fiber.
[0053]
Table 1 shows the results. From the same table, the variation coefficient (U%) of the unevenness of the thickness of the undrawn yarn is 0.75%, the variation coefficient (U%) of the unevenness of the drawn yarn is 0.45, the maximum U% value and the minimum value of the drawn yarn. The difference in U% value (ΔU%) is 0.80%, the single fiber fineness of the drawn yarn is 56 / 36f (dtex), the crimp (CC) of the drawn yarn is 32, and the spinneret is washed. And stable stretching was performed for 42 hours.
[0054]
(Example 2)
A composite spinneret similar to that in Example 1 was used except that the length L1 of the thin tube portion was 1.3 mm, the length L2 of the discharge opening portion was 0.3 mm, and the gradually increasing angle θ2 of the second stage was 20 °. The spinning conditions were the same as in Example 1.
[0055]
Table 1 shows the results. From the table, the variation coefficient (U%) of the thickness unevenness of the undrawn yarn is 0.75%, the variation coefficient (U%) of the unevenness of the drawn yarn is 0.45, and the maximum U% (M) of the drawn yarn. The difference between the value and the minimum U% (M) value (ΔU%) is 0.80%, the single fiber fineness of the drawn yarn is 56 / 36f (dtex), and the crimp (CC) of the drawn yarn is 34, As in Example 1, stable drawing could be performed for 42 hours without washing the spinneret.
[0056]
(Comparative Example 1)
Example 1 except that the length L1 of the thin tube portion was 1.5 mm, the length L2 of the discharge opening was 0 mm, the diameter D2 of the opening end was 0.5 mm, and the gradually increasing angle θ of the opening end was 15 ° in one step. Using a composite spinneret having the same structure as in Example 1, spinning was performed under the same spinning conditions as in Example 1 except that the draft rate was changed to 877, and a polyester composite multifilament fiber having the same fineness as in Example 1 was drawn. Yarn was obtained.
[0057]
Table 1 shows the results. From the same table, the variation coefficient (U%) of the unevenness of the thickness of the undrawn yarn is 0.70%, the variation coefficient (U%) of the unevenness of the drawn yarn is 0.4, and the maximum U% value and the minimum value of the drawn yarn are minimum. The difference in U% value (ΔU%) was 0.50%, and the crimp (CC) of the drawn yarn was 35. However, even after washing the spinneret, stable drawing could not be performed for 24 hours.
[0058]
(Comparative Example 2)
The length L1 of the thin tube portion is 1.5 mm, the diameter D1 is 0.4 mm, the length L2 of the discharge opening is 0 mm, the diameter of the opening end is 0.5 mm, and the gradually increasing angle of the discharge opening is 15 ° 1 A polyester composite multifilament having the same fineness as that of Example 1 under the same spinning conditions as in Example 1 except that the composite spinneret having the steps was used, and that the discharge linear speed was 3.7 m / min and the draft rate was 877. A drawn fiber was obtained.
[0059]
Table 1 shows the results. From the table, the variation count (U%) of the thickness unevenness of the undrawn yarn is 1.00%, the variation count (U%) of the thickness unevenness of the drawn yarn is 0.6, and the maximum U% value and the minimum value of the drawn yarn. The difference in U% value (ΔU%) was 2.50%, and the crimp (CC) of the drawn yarn was 35. Even when the spinneret was washed, the yarn was frequently broken and stable drawing could not be performed.
[0060]
(Comparative Example 3)
Same as Example 1 except that the length L1 of the thin tube portion was 1.5 mm, the diameter D1 was 0.5 mm, the length L2 of the discharge opening was 0 mm, and the gradually increasing angle θ of the opening end was 15 ° per step. Drawing of a polyester composite multifilament fiber having the same fineness as in Example 1 under the same spinning conditions as in Example 1 except that a composite spinneret having the structure of Yarn was obtained.
[0061]
Table 1 shows the results. As shown in the table, as long as the spinneret was washed, stable drawing could be performed for 24 hours, and the crimping (CC) of the drawn yarn was as large as 36, and the crimpability was high. (U%) is 1.40%, and the variation coefficient (U%) of the drawn yarn thickness unevenness is so large that measurement is impossible, and the difference between the maximum U% value and the minimum U% value of the drawn yarn (ΔU% ) Was extremely high at 3.00%, and uniform dyeing could not be expected.
[0062]
(Comparative Example 4)
The same structure as in Example 1 except that the length L1 of the thin tube portion is 1.4 mm, the length L2 of the discharge opening portion is 0.2 mm, and the gradually increasing angle θ2 of the second stage on the opening end side is 50 °. A drawn yarn of a polyester composite multifilament fiber having the same fineness as that of Example 1 was obtained under the same spinning conditions as in Example 1 except that the discharge linear velocity was set to 2.4 m / min. Was. As a result, as shown in Table 1, the ejection from the spinneret was not stable, and winding was impossible.
[0063]
[Table 1]

[0064]
As is apparent from the above description, the discharge opening of the composite spinneret used in the production of the latently crimpable polyester composite multifilament fiber of the present invention has a discharge opening whose angle gradually increases in a plurality of stages toward the narrow tube portion and the outlet. The spinneret is used to satisfy predetermined spinning conditions, thereby causing problems such as unevenness of fiber thickness, yarn breakage, etc., which are conventionally caused by fluctuations in the ejection linear speed. Can be effectively prevented.
[0065]
As a result, it is naturally possible to stably spin a conjugate fiber having high latent crimpability, sufficient swelling feeling and stretchability, and ordinary fineness. It has become impossible, especially it is possible to stably spin a fine fiber composite fiber having a high potential crimping property and sufficient swelling feeling and stretchability, and by using those fibers, A woven or knitted fabric having excellent elasticity and plumpness, excellent flexibility, and high stretchability can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an essential part of one embodiment of a melt spinneret according to the present invention.
[Explanation of symbols]
10 Spinneret
11 discharge holes
12 junction
13 Thin tube
14 Discharge opening
L1 Length of thin tube
L2 Length of discharge opening
D1 Diameter of thin tube
D2 Open end diameter of discharge opening
θ, θ1, θ2 Increasing angle of discharge opening

Claims

A spinneret for melt-spinning a joint type latently crimped conjugate polyester fiber in which two kinds of polyesters are independently supplied, and the two are joined and discharged,
A discharge opening having an arbitrary cross-sectional shape, the cross-sectional area of which gradually increases from the upstream side to the downstream side, and a uniform-diameter in which two types of polyesters are compounded and connected to the upstream side of the discharge opening. With a thin tube section,
A spinneret for a polyester composite multifilament fiber, wherein a gradually increasing angle θ between the central axis and a wall surface of the discharge opening is discontinuous.

The tube diameter D1 of the thin tube portion is smaller than 0.4 mm, the ratio (L1 / D1) of the length L1 to the tube diameter D1 is 1.5 to 5.0, and the diameter D2 of the discharge opening is The spinneret according to claim 1, wherein the diameter is 0.5 mm or more.

The spinneret according to any one of claims 1 to 2, wherein the gradually increasing angle θ between the central axis of the discharge opening and the wall surface increases discontinuously within a range of 10 ° to 45 °. .

A method for producing a bonded composite multifilament fiber obtained by bonding a high-viscosity polyester (A) and a low-viscosity polyester (B) satisfying the following formulas (1) and (2):
A composite stream of a high-viscosity polyester (A) and a low-viscosity polyester (B) upstream of the spinneret according to any one of claims 1 to 3, and a discharge linear speed of 3.5 m / min or more and a spinning draft of 800 or more. A method for producing a polyester composite multifilament fiber, wherein the coefficient of variation U% (L) of the thickness unevenness of undrawn yarn fibers is discharged from the discharge opening to 0.8% or less.
4/6 ≦ W ≦ 6/4 (1)
[Η] A- [η] B> 0.145 (2)
In the formula, [η] A and [η] B represent the intrinsic viscosities of A and B, respectively, and W represents the junction ratio (weight ratio) of A / B.

The method for producing a polyester composite multifilament fiber according to claim 4, wherein the high-viscosity polyester (A) is a copolymerized polyethylene terephthalate obtained by copolymerizing a third component with 5 to 15 mol%.

6. The method according to claim 4, wherein the low-viscosity polyester (B) is polyethylene terephthalate.

It is obtained by the production method according to any one of claims 4 to 6,
The fineness of the single fiber is 0.6 to 3.3 dtex, the variation coefficient (U%) of the thickness unevenness of the multifilament fiber is 0.2 to 0.6%, and the difference between the maximum U% value and the minimum U% value. (△ U%) is 2% or less, and the crimp ratio (CC) is 20 to 45%.

The fine fiber according to claim 7, wherein one of the two polyesters having different melt viscosities is a copolymerized polyethylene terephthalate obtained by copolymerizing a third component with 5 to 15 mol%.

9. The fine fiber according to claim 7, wherein another one of the two polyesters having different melt viscosities is polyethylene terephthalate.

A woven or knitted fabric using the fine fiber according to any one of claims 7 to 9.