JP4205500B2

JP4205500B2 - Hollow polytrimethylene terephthalate composite short fiber and method for producing the same

Info

Publication number: JP4205500B2
Application number: JP2003182736A
Authority: JP
Inventors: 敏弘山田
Original assignee: ソロテックス株式会社
Priority date: 2003-06-26
Filing date: 2003-06-26
Publication date: 2009-01-07
Anticipated expiration: 2023-06-26
Also published as: CN1768171A; CN100374633C; WO2005001175A1; EP1636405A1; KR20060022643A; US20060210793A1; TW200504256A; MY140927A; EP1636405A4; HK1090395A1; US20090035568A1; JP2005015957A; CA2519586A1

Description

【０００１】
【発明の属する技術分野】
本発明は、潜在捲縮性を有する中空ポリトリメチレンテレフタレート系複合短繊維に関するものである。さらに詳しくは、嵩高性および弾性回復性などに優れた不織布、織編物、クッション材などを得るのに適した中空ポリトリメチレンテレフタレート系複合短繊維に関するものである。
【０００２】
【従来の技術】
ポリトリメチレンテレフタレート繊維は、ポリエステル本来の特性である優れた寸法安定性、耐光性、低吸湿性、熱セット性を維持しながら、低弾性率、弾性回復率および易染性に優れた特性を持っている。このため、ポリトリメチレンテレフタレート繊維は、衣料用途、工業用途繊維として注目されている。一方、ストレッチ機能を有する織編物あるいは不織布などを得るために、２種類の極限粘度の異なったポリエステルを接合した潜在捲縮性の複合繊維を使用することはよく知られている。このような潜在捲縮性ポリエステル系複合繊維を得るために、両ポリエステルの極限粘度差を可能な限り大きくして、繊維にしたときの収縮差を大きくし、さらには、紡糸操業性を向上させるために種々の提案がなされている。例えば、粘度の異なるポリマーを一対の吐出孔から吐出させて、サイドバイサイド型の複合繊維を形成するようにした口金において、一対をなす吐出孔が口金面と直行する方向に対してなす各々の傾斜角度や、一対の吐出孔間の距離などを規制した溶融紡糸用口金（特許文献１）、繊維横断面の両ポリエステルの接合面形状を規定したサイドバイサイド型複合繊維（特許文献２）などがある。
しかしながら、高度な潜在捲縮性能を得るために２種類のポリエステルの極限粘度差を大きくすると、溶融吐出時に吐出糸条が屈曲を起こし、さらに極限粘度差が大きくなると屈曲が過度に進み、隣接した糸条どうしが融着したり、糸条が紡糸口金に付着して切断したりするため安定して紡糸を行うことができない。更に、ポリトリメチレンテレフタレート複合繊維の場合、従来から良く用いられているポリエチレンテレフタレート複合繊維とは異なり繊維の剛性度が低いので、潜在化した捲縮が発現する時に、小さな捲縮が多く発現してしまい所望の嵩高性が得にくいという欠点を有していた。
【０００３】
【特許文献１】
特公昭６１−６０１６3号公報（特許請求の範囲）
【特許文献２】
特開２０００−２３９９２７号公報（特許請求の範囲）
【０００４】
【発明が解決しようとする課題】
本発明は、上記従来技術を背景になされたもので、その目的は、優れた嵩高性および弾性回復性を有しており、不織布、嵩高糸、織編物、クッション材などを得るのに適した潜在捲縮性を有する中空ポリトリメチレンテレフタレート系複合短繊維を提供することにある。
【０００５】
【課題を解決するための手段】
本発明者は、上記問題点を解決しようと鋭意検討の結果、極限粘度の異なる２種のポリトリメチレンテレフタレート系ポリエステルを特定の極限粘度範囲で使い、かつ、繊維の横断面を中空にした複合短繊維にすることで達成できることを見出し本発明に到達したものである。
すなわち、本発明は、極限粘度が互いに異なるポリトリメチレンテレフタレート系ポリエステル成分が、サイドバイサイド型または偏心芯鞘型に配された複合短繊維であって、高粘度ポリエステル成分の極限粘度が０．５０〜１．４０ｄｌ／g、低粘度ポリエステル成分の極限粘度が０．４０〜１．３０ｄｌ／g、高粘度ポリエステル成分と低粘度ポリエステル成分との極限粘度差が０．１０〜０．５０ｄｌ／gであり、該複合短繊維がその横断面に中空部を有しており、該中空部の該横断面に占める面積割合が２〜１５％であり、かつ、下記に定義するウェブ収縮率が３０〜７０％であることを特徴とする中空ポリトリメチレンテレフタレート系複合短繊維（以下「中空複合短繊維」ともいう）に関する。
＜ウェブ収縮率＞
熱収縮を施す前の繊維長５１ｍｍの短繊維をローラカードに通して目付３０ｇ／ｍ²のウェブを作成し、該ウェブから２０ｃｍ×２０ｃｍのサンプルを切り取り、これを１２０℃の熱風循環高温乾燥機に入れて１０分間放置し、自由熱収縮させ、次式により求めた値。
ウェブ収縮率（％）＝〔（Ａ−Ｂ）／Ａ〕×１００
ここで、Ａは熱収縮前のサンプルの面積（４００ｃｍ²）、Ｂは熱収縮後のサンプルの面積（ｃｍ²）を示す。
本発明の中空ポリトリメチレンテレフタレート系複合短繊維は、例えば、極限粘度が互いに異なるポリトリメチレンテレフタレート系ポリエステル成分がサイドバイサイド型または偏心芯鞘型に配された中空複合短繊維の製造方法であって、高粘度ポリエステル成分の極限粘度が０．５０〜１．４０ｄｌ／g、低粘度ポリエステル成分の極限粘度が０．４０〜１．３０ｄｌ／g、高粘度ポリエステル成分と低粘度ポリエステル成分との極限粘度差が０．１０〜０．５０ｄｌ／gである高粘度ポリエステル成分および低粘度ポリエステル成分を、中空サイドバイサイド型複合溶融紡糸装置または中空偏心芯鞘型複合溶融紡糸装置を用いて、溶融紡糸して得られる中空未延伸糸を、第１段延伸温度４５〜６０℃、第２段延伸温度８５〜１２０℃とし、第２段目延伸倍率を０．９０〜１．０かつ全延伸倍率を未延伸糸破断倍率の６０〜８０％で延伸したのち、５０〜８０℃の温度条件で機械捲縮を付与したのち、８０℃以下で弛緩熱処理し、短繊維状にカットすることよって、製造することができる。
【０００６】
【発明の実施の形態】
以下本発明の実施形態について詳細に説明する。
本発明でいうポリトリメチレンテレフタレートとは、トリメチレンテレフタレート単位を主たる繰り返し単位とするポリエステルであって、本発明の目的を阻害しない範囲内で、例えば全酸成分を基準として１５モル％以下、好ましくは５モル％以下で第３成分を共重合したポリエステルであっても良い。
好ましく用いられる第３成分としては、例えば、イソフタル酸、コハク酸、アジピン酸、２，６−ナフタレンジカルボン酸、金属スルホイソフタル酸などの酸成分や、１，４−ブタンジオール、１，６−ヘキサンジオール、シクロヘキサンジオール、シクロヘキサンジメタノールなどのジオール成分など、各種のものを用いることができ、紡糸安定性などを考慮して適宜選択すれば良い。
また、必要に応じて、各種の添加剤、例えば、艶消し剤、熱安定剤、消泡剤、整色剤、難燃剤、酸化防止剤、紫外線吸収剤、赤外線吸収剤、蛍光増白剤、着色顔料などを添加したポリトリメチレンテレフタレートであっても良い。
【０００７】
本発明においては、ポリトリメチレンテレフタレートの極限粘度（ｏ−クロロフェノールを溶媒として使用し温度３５℃で測定）は、高粘度成分である第１成分が０．５〜１．４ｄｌ／ｇ、好ましくは０．８〜１．３ｄｌ／ｇでなければならない。
極限粘度が１．４ｄｌ／ｇを超えると、溶融時の粘度が極端に高くなるため通常のポリエステルの生産設備が使えなくなるばかりか、溶融粘度を下げるために溶融温度を２８０℃以上にする必要があり、ポリマーを分解し始めるので好ましくない。一方、極限粘度０．５ｄｌ／ｇ未満では、第２成分との極限粘度差が小さくなり過ぎて十分な潜在捲縮性能が得られない。
また、低粘度成分である第２成分の極限粘度は、０．４〜１．３ｄｌ／ｇ、好ましくは０．５〜１．０ｄｌ／ｇでなければならない。極限粘度が０．４ｄｌ／ｇ未満では、溶融時の粘度が低くなり過ぎて紡糸時に断糸が発生して安定生産ができない。一方、極限粘度が１．３ｄｌ／ｇを超えると、第１成分との極限粘度差が小さくなり過ぎて十分な潜在捲縮性能が得られない。
さらに、第１成分と第２成分との極限粘度差は、０．１０〜０．５０ｄｌ／ｇ、好ましくは０．２〜０．４ｄｌ／ｇでなければならない。極限粘度差が０．１ｄｌ／ｇ未満では、潜在捲縮性能が不十分であり、一方、極限粘度差が０．５ｄｌ／ｇを超えると、溶融吐出時に吐出糸条の屈曲が過度に進み、隣接した糸条どうしが融着したり、糸条が紡糸口金に付着して切断したりするため安定して紡糸を行うことができない。
【０００８】
なお、各成分の構成は、潜在捲縮性能と紡糸性を考慮して決めれば良いが、第１成分／第２成分の重量構成比率が３０／７０〜７０／３０であることが好ましく、より好ましくは５０／５０近辺である。
【０００９】
本発明の中空複合短繊維は、任意の横断面においては中空部を有する。つまり、溶融ポリマーが口金より吐出される際、ポリマー中央部に空洞があるためにポリマーが屈曲しようとする力に対して強い抵抗力が生じて紡糸の安定性が向上する。また、得られる中空複合短繊維も、中空部を有しているために剛性度が向上し、適切な形のスパイラル捲縮が発現し嵩高であり、これを用いた不織布なども優れた嵩高性、弾性回復性を有するものとなる。
本発明の中空複合短繊維の中空率は、２〜１５％であり、好ましくは５〜１０％である。中空率が２％未満では、ポリマー紡出時の糸条の屈曲が起こり紡糸調子が不良となる。さらにには、小さな捲縮が発現するので嵩高とはならない。一方、中空率が１５％を超えると、２成分のポリマーの接合面が小さくなり過ぎて潜在捲縮性能が低下するので好ましくない。
本発明の中空複合短繊維において、中空率を２〜１５％にするには、複合紡糸口金の吐出孔形状や、溶融ポリマー温度、紡糸冷却の風量などにより、容易に調整することができる。
【００１０】
本発明の中空複合短繊維は、例えば、繊維の横断面において、中空部が、低粘度ポリエステル成分または高粘度ポリエステル成分のいずれか一方の成分中に存在していることが望ましい。例えば、▲１▼サイド−サイド型中空複合短繊維の場合、第１成分あるいは第２成分のいずれかが、繊維断面の半分を超えて占められており、かつ当該繊維断面の半分を超えて占められている成分中に中空部が存在する例や、▲２▼偏心芯鞘型中空複合短繊維の場合、芯部あるいは鞘部のいずれか一方にのみ中空部が存在する例が挙げられる。
このような中空複合短繊維の形態は、潜在化した捲縮が発現するときのスパイラルループを大きくするという効果を奏する。
【００１１】
なお、本発明の中空複合短繊維の単糸断面形状および中空部断面形状は特に限定されるものではなく、円形、三角形、扁平、多葉、多孔など用途目的に合わせて適宜選択すれば良い。
また、本発明の中空複合短繊維の単繊度は、１〜５ｄｔｅｘ、好ましくは１．５〜３ｄｔｅｘのものを用いることができる。
さらに、本発明の中空複合短繊維のカット長は、通常、３〜１５０ｍｍ、好ましくは３０〜７５ｍｍ程度である。
【００１２】
本発明の中空複合短繊維は、下記に定義するウェブ収縮率が３０〜７０％、好ましくは４０〜６０％であることが必要である。ウエブ収縮率は潜在捲縮性能の尺度であり、ウェブ収縮率が３０％以上である短繊維は、織編物、不織布にした場合、嵩高性およびストレッチ性を十分に発揮できる。しかし、ウエブ収縮率が７０％を超えるような短繊維では、小さなスパイラル捲縮が数多く発現するため、ストレッチ性はあるものの、嵩高性が損なわれ風合いが硬くなる。さらには、紡績などのカーディング工程で捲縮が発現し、工程トラブルを引き起こす。一方、ウェブ収縮率が３０％未満では、スパイラル捲縮の発現が弱く、ストレッチ性が不十分となる。
ウェブ収縮率を３０〜７０％の範囲に調整するには、使用するポリエステルの極限粘度に応じた、延伸倍率、延伸温度条件、中空率の設定によってなされる。
＜ウェブ収縮率＞
熱収縮を施す前の繊維長５１ｍｍの短繊維をローラカードに通して目付３０ｇ／ｍ²のウェブを作成し、該ウェブから２０ｃｍ×２０ｃｍのサンプルを切り取り、これを１２０℃の熱風循環高温乾燥機に入れて、１０分間放置し、自由熱収縮させ、次式により求めた値。
ウェブ収縮率（％）＝〔（Ａ−Ｂ）／Ａ〕×１００
ここで、Ａは熱収縮前のサンプルの面積（４００ｃｍ²）、Ｂは熱収縮後のサンプルの面積（ｃｍ²）を示す。
【００１３】
なお、本発明の中空複合短繊維は、通常、充填式クリンパー、ギア式クリンパーなどの捲縮装置により、捲縮が付与されている。
ここで、本発明の中空複合短繊維の捲縮率は、通常、１０〜２５％、好ましくは１５〜２０％である。この捲縮率は、捲縮加工時の温度や捲縮数によって容易に調整することができる。
ここで、捲縮率は、ＪＩＳＬ−１０１５化学繊維ステープル試験方法の捲縮試験法によって測定された値である。
【００１４】
本発明の中空複合短繊維は、例えば、極限粘度が０．５０〜１．４０ｄｌ／ｇのポリトリメチレンテレフタレートからなる高粘度ポリエステル成分と、極限粘度が０．４０〜１．３０ｄｌ／ｇポリトリメチレンテレフタレートからなる低粘度ポリエステル成分であって、かつ高粘度ポリエステル成分と低粘度ポリエステル成分との極限粘度差が０．１０〜０．５０ｄｌ／gである高粘度ポリエステル成分および低粘度ポリエステル成分を、中空サイドバイサイド型複合溶融紡糸装置または中空偏心芯鞘型複合溶融紡糸装置を用いて、溶融紡糸して得られる未延伸糸を、第１段延伸温度４５〜６０℃、好ましくは５０〜６０℃、第２段延伸温度８５〜１２０℃、好ましくは９０〜１１０℃、第２段目延伸倍率を０．９０〜１．０かつ全延伸倍率を未延伸糸破断倍率の６０〜８０％、好ましくは６５〜７５％で延伸したのち、５０〜８０℃、好ましくは６０〜７０℃の温度条件で機械捲縮を付与したのち、８０℃以下で弛緩熱処理し、短繊維状にカットすることによって、製造することができる。
【００１５】
また、第１段延伸温度（通常は温水温度）は、４５〜６０℃であり、４５℃未満では、加熱不足により延伸張力が高く糸切れを発生しやすく、一方、６０℃を超えると結晶化による糸切れが発生する。
第２段延伸温度と倍率は、潜在捲縮性能に関係し、８５〜１２０℃にて、０．９０〜１．０倍に延伸する必要がある。８５℃未満では、得られた短繊維に機械的な作用が加わった時に、潜在捲縮が顕在化しやすく、紡績あるいは不織布化工程でカード機に通したとき、カーディング工程で過度の捲縮が発現し、得られたウエブにネップ、穴あきなどの欠点を生じる。一方、１２０℃を超えると、潜在捲縮性能が低下する。２段延伸倍率を１．０倍より大きくし実質延伸を行うと、後の捲縮加工時にスパイラル捲縮が多く発現し、やはりカーディング工程の通過が困難となる。第２段の延伸では定長あるいは制限収縮熱処理をする必要があるが、延伸倍率が０．９０より低くなると繊維が熱セットされ過ぎて潜在捲縮性能が低下する。好ましい倍率は、０．９２〜０．９８である。
さらに、第１段延伸と第２段延伸における全延伸倍率は、未延伸糸破断倍率の６０〜８０％であり、６０％未満では潜在捲縮性能が低下し、一方、８０％を超えると、延伸での糸切れが激しくなり生産が困難となる。
さらに、本発明の中空複合短繊維は、通常、充填式クリンパー、ギア式クリンパーなどの捲縮装置により捲縮が付与されるが、この際の捲縮加工時の捲縮温度は、５０〜８０℃であり、５０℃未満では十分な捲縮率が得にくく、一方、８０℃を超えると、捲縮加工時に本来潜在化すべきスパイラル捲縮が発現するので、カード工程の通過性が悪化する。
また、捲縮加工条件としては、捲縮数を１０〜１５個／２５ｍｍとしておくのがカーディングなどの後加工のため好ましい。
さらに、捲縮加工後、８０℃以下で弛緩熱処理を行なう。８０℃を超えると、スパイラル捲縮が発現してしまう。弛緩熱処理温度の下限については特にないが、捲縮加工前の繊維には、通常、仕上油剤のエマルジョンが賦与されているので、水分を除去するため４０℃以上で行われるのが普通である。弛緩熱処理時間は、通常、３０〜６０分である。
本発明の中空複合短繊維は、弛緩熱処理後、トウ切断機、例えばグルグルカッターやロータリーカッターなどにより、カット長３〜１５０ｍｍに切断することによって得られる。
【００１６】
【実施例】
以下、実施例により、本発明をさらに具体的に説明する。なお、実施例中における各項目は次の方法で測定した。
（１）極限粘度〔η〕
オルソクロロフェノールを溶媒として、３５℃の温度でウベローデ粘度管にて測定した。
（２）冷却風風速
温度２５℃、湿度６５％の空気を、吐出糸条の走行方向に対して直角に吹き付けて冷却する際の風の速度。
（３）中空率（％）
任意の繊維横断面中に中空部が占める割合を求めた。
（４）未延伸糸破断倍率
定速伸張型引張り試験機にて、つかみ幅１０ｃｍ、引張り速度１００ｃｍ／分の条件にて測定した。
（５）捲縮率
ＪＩＳＬ−１０１５に準拠した。
（６）紡糸安定性
人為的あるいは機械的要因に起因する断糸を除き、紡糸機運転中に発生した断糸回数を記録し、８時間・１錘当たりの断糸回数により○、△、×で表した。
○ ：断糸回数ゼロ
△ ：断糸回数１〜２回／８時間・錘
× ：断糸回数３回以上／８時間・錘
（７）ウェブ収縮率（％）
熱処理を施す前の短繊維をローラーカードに通して、目付３０ｇ／ｍ²のウェブを作成し、該ウェブから２０ｃｍ×２０ｃｍのサンプルを切り取り、これを１２０℃の熱風循環恒温乾燥機に入れて１０分間、自由収縮させたときの収縮を次式により求めた。
ウェブ収縮率（％）＝〔（Ａ−Ｂ）／Ａ〕×１００
ただし、Ａ：熱処理前面積（ｃｍ²）
Ｂ：熱処理後面積（ｃｍ²）
（８）不織布弾性回復率、嵩性
熱処理を施す前の短繊維をローラーカードに通してウェブを作成し、該ウェブを積層してニードルパンチを施し、目付け約５０ｇ／ｍ²の不織布を作製する。この不織布を１２０℃のオーブン中で１０分熱処理したあと、不織布の嵩密度を測定する。さらに、不織布を幅２５ｍｍに裁断し、定速伸張型引張り試験機にて、掴み幅１００ｍｍ、伸張速度１００ｍｍ／分にて破断伸度と弾性回復率を求めた。
弾性回復率＝（Ｂ−Ｃ）／Ｂｘ１００（％）
（Ｂは不織布の伸度の８０％の値、ＣはＢの値まで伸張した後、荷重を外し１分間放置後の測定前の試料長に対する伸度を示す。）
（９）総合判定
紡糸安定性と不織布嵩性、不織布弾性回復率から総合的に判断した。
良：紡糸8時間糸切れなきこと、不織布嵩１５ｃｍ³／ｇ以上、不織布弾性回復率８０％以上を同時に満足する。
不良：上記３要件のいずれかを満足しない。
【００１７】
実施例１〜２、比較例１〜６
第１成分および第２成分の極限粘度の組合せを変えたポリマーを、複合溶融紡糸装置を用い、偏心中空断面の孔数１，０００ホール口金にて紡糸温度２４５℃〜２９０℃、成分構成比率（Ａ／Ｂ）（重量比）＝５０／５０の偏心芯鞘型として吐出量６９０ｇ／分、巻き取速度１，３００ｍ／分で８時間の連続紡糸を行って紡糸安定性を調査した。得られた未延伸糸を用い延伸を行ったが、この時の紡糸条件、未延伸糸性能、延伸条件を表１に示した。延伸に引続き７５℃で機械捲縮を付与した後に５５℃で３０分、弛緩熱処理を施し、５１ｍｍにカットして短繊維を得た。一方、得られた短繊維をカードでウェブとなした後、収縮率、不織布の特性を測定し、表１〜２の結果を得た。比較例３の条件では、紡糸糸切れが頻発し、未延伸糸の採取が困難であった。
【００１８】
比較例７
紡糸口金の中空を形成する円周状スリットのＰＣＤ（スリット内周の直径）を大きくすると共に冷却風速を速くして中空率を大きくした以外は、実施例１と同様にして得られた結果を表２に示す。
【００１９】
比較例８
紡糸口金を中実の孔数１，０００ホールに変え、冷却風速をやゝ速くした以外は実施例１と同様にして得られた結果を表２に示す。
【００２０】
【表１】

【００２１】
【表２】

【００２２】
【発明の効果】
本発明の中空ポリトリメチレンテレフタレート系複合短繊維は、潜在捲縮性を有し、嵩高性および弾性回復性などに優れ、不織布、織編物、クッション材などを得るのに適している。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hollow polytrimethylene terephthalate composite short fiber having latent crimpability. More specifically, the present invention relates to a hollow polytrimethylene terephthalate composite short fiber suitable for obtaining a nonwoven fabric, a woven or knitted fabric, a cushioning material and the like excellent in bulkiness and elastic recovery.
[0002]
[Prior art]
Polytrimethylene terephthalate fiber has excellent properties such as low elastic modulus, elastic recovery, and easy dyeing while maintaining the excellent dimensional stability, light resistance, low moisture absorption, and heat setting properties that are inherent to polyester. have. For this reason, polytrimethylene terephthalate fiber has attracted attention as a fiber for clothing and industrial use. On the other hand, in order to obtain a woven or knitted fabric or nonwoven fabric having a stretch function, it is well known to use a latent crimpable conjugate fiber obtained by joining two types of polyesters having different intrinsic viscosities. In order to obtain such a latently crimpable polyester-based composite fiber, the difference in intrinsic viscosity between the two polyesters is increased as much as possible to increase the difference in shrinkage when the fiber is formed, and further, the spinning operability is improved. Various proposals have been made for this purpose. For example, in a die in which polymers having different viscosities are ejected from a pair of ejection holes to form a side-by-side type composite fiber, each inclination angle formed by a pair of ejection holes with respect to a direction perpendicular to the die surface There are also a melt spinning die (Patent Document 1) that regulates the distance between a pair of discharge holes, and a side-by-side composite fiber (Patent Document 2) that defines the joint surface shape of both polyesters in the fiber cross section.
However, if the intrinsic viscosity difference between the two types of polyester is increased in order to obtain a high level of crimp performance, the discharge yarn will bend during melt discharge, and if the intrinsic viscosity difference is further increased, the bending will proceed excessively and become adjacent. Spinning cannot be performed stably because the yarns are fused together or the yarns adhere to the spinneret and are cut. Furthermore, in the case of polytrimethylene terephthalate conjugate fiber, unlike the polyethylene terephthalate conjugate fiber that has been used well in the past, the stiffness of the fiber is low, so when latent crimps appear, many small crimps appear. As a result, the desired bulkiness is difficult to obtain.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 61-60163 (Claims)
[Patent Document 2]
JP 2000-239927 (Claims)
[0004]
[Problems to be solved by the invention]
The present invention has been made against the background of the above-described conventional technology, and the object thereof is excellent in bulkiness and elastic recovery, and is suitable for obtaining nonwoven fabrics, bulky yarns, woven and knitted fabrics, cushion materials, and the like. It is an object of the present invention to provide a hollow polytrimethylene terephthalate composite short fiber having latent crimpability.
[0005]
[Means for Solving the Problems]
As a result of diligent studies to solve the above problems, the present inventor used two types of polytrimethylene terephthalate polyesters having different intrinsic viscosities in a specific intrinsic viscosity range, and a composite having a hollow fiber cross section The present inventors have found that this can be achieved by using short fibers.
That is, the present invention is a composite short fiber in which polytrimethylene terephthalate polyester components having different intrinsic viscosities are arranged in a side-by-side type or an eccentric core-sheath type, and the intrinsic viscosity of the high-viscosity polyester component is 0.50 to 1.40 dl / g, the intrinsic viscosity of the low viscosity polyester component is 0.40 to 1.30 dl / g, and the intrinsic viscosity difference between the high viscosity polyester component and the low viscosity polyester component is 0.10 to 0.50 dl / g. The composite short fiber has a hollow portion in its cross section, the area ratio of the hollow portion in the cross section is 2 to 15%, and the web shrinkage rate defined below is 30 to 70. % Hollow polytrimethylene terephthalate composite short fibers (hereinafter also referred to as “hollow composite short fibers”).
<Web shrinkage>
A short fiber having a fiber length of 51 mm before being subjected to heat shrinkage is passed through a roller card to prepare a web having a basis weight of 30 g / m ^2, a 20 cm × 20 cm sample is cut from the web, and this is heated at 120 ° C. with a hot air circulation high temperature dryer The sample was allowed to stand for 10 minutes and subjected to free heat shrinkage, and the value obtained by the following formula.
Web shrinkage (%) = [(A−B) / A] × 100
Here, A represents the area (400 cm ² ) of the sample before heat shrinkage, and B represents the area (cm ² ) of the sample after heat shrinkage.
The hollow polytrimethylene terephthalate composite short fiber of the present invention is, for example, a method for producing a hollow composite short fiber in which polytrimethylene terephthalate polyester components having different intrinsic viscosities are arranged in a side-by-side type or an eccentric core-sheath type. The intrinsic viscosity of the high viscosity polyester component is 0.50 to 1.40 dl / g, the intrinsic viscosity of the low viscosity polyester component is 0.40 to 1.30 dl / g, and the intrinsic viscosity of the high viscosity polyester component and the low viscosity polyester component A high-viscosity polyester component and a low-viscosity polyester component having a difference of 0.10 to 0.50 dl / g are obtained by melt spinning using a hollow side-by-side type composite melt spinning apparatus or a hollow eccentric core-sheath type composite melt spinning apparatus. The hollow undrawn yarn to be made has a first stage drawing temperature of 45 to 60 ° C. and a second stage drawing temperature of 85 to 120 ° C., After the second stage draw ratio is 0.90 to 1.0 and the total draw ratio is drawn at 60 to 80% of the undrawn yarn breaking ratio, mechanical crimping is applied at a temperature condition of 50 to 80 ° C., and then 80 It can be manufactured by performing a relaxation heat treatment at a temperature below 0 ° C. and cutting into short fibers.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The polytrimethylene terephthalate referred to in the present invention is a polyester having a trimethylene terephthalate unit as a main repeating unit, and within a range that does not impair the object of the present invention, for example, 15 mol% or less, preferably based on the total acid component, May be a polyester copolymerized with 5 mol% or less of the third component.
As the third component preferably used, for example, acid components such as isophthalic acid, succinic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, metal sulfoisophthalic acid, 1,4-butanediol, 1,6-hexane Various types such as a diol component such as diol, cyclohexanediol, and cyclohexanedimethanol can be used, and may be appropriately selected in consideration of spinning stability and the like.
If necessary, various additives such as matting agents, heat stabilizers, antifoaming agents, color modifiers, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, fluorescent whitening agents, Polytrimethylene terephthalate to which a coloring pigment or the like is added may be used.
[0007]
In the present invention, the intrinsic viscosity of polytrimethylene terephthalate (measured at a temperature of 35 ° C. using o-chlorophenol as a solvent) is preferably 0.5 to 1.4 dl / g, the first component being a high viscosity component, Must be between 0.8 and 1.3 dl / g.
When the intrinsic viscosity exceeds 1.4 dl / g, the viscosity at the time of melting becomes extremely high, so not only the normal polyester production equipment can be used, but also the melting temperature needs to be 280 ° C. or higher in order to lower the melt viscosity. Yes, since it starts to decompose the polymer, it is not preferable. On the other hand, if the intrinsic viscosity is less than 0.5 dl / g, the intrinsic viscosity difference from the second component becomes too small and sufficient latent crimping performance cannot be obtained.
The intrinsic viscosity of the second component, which is a low viscosity component, should be 0.4 to 1.3 dl / g, preferably 0.5 to 1.0 dl / g. If the intrinsic viscosity is less than 0.4 dl / g, the viscosity at the time of melting becomes too low and the yarn is broken during spinning, so that stable production cannot be achieved. On the other hand, if the intrinsic viscosity exceeds 1.3 dl / g, the intrinsic viscosity difference from the first component becomes too small and sufficient latent crimping performance cannot be obtained.
Furthermore, the intrinsic viscosity difference between the first component and the second component should be 0.10 to 0.50 dl / g, preferably 0.2 to 0.4 dl / g. If the difference in intrinsic viscosity is less than 0.1 dl / g, the latent crimping performance is insufficient. On the other hand, if the difference in intrinsic viscosity exceeds 0.5 dl / g, the bending of the discharge yarn proceeds excessively during melt discharge, Adjacent yarns are fused together, or the yarns adhere to the spinneret and cut, so that stable spinning cannot be performed.
[0008]
The composition of each component may be determined in consideration of the latent crimp performance and spinnability, but the weight composition ratio of the first component / second component is preferably 30/70 to 70/30, more Preferably it is around 50/50.
[0009]
The hollow composite short fiber of the present invention has a hollow portion in an arbitrary cross section. That is, when the molten polymer is discharged from the die, since there is a cavity in the center of the polymer, a strong resistance force is generated against the force that the polymer tries to bend and the spinning stability is improved. In addition, the resulting hollow composite short fiber also has a hollow portion, so that the rigidity is improved, a spiral crimp of an appropriate shape is expressed and bulky, and a nonwoven fabric using the same is also bulky. It will have elastic recovery.
The hollow ratio of the hollow composite short fiber of the present invention is 2 to 15%, preferably 5 to 10%. If the hollowness is less than 2%, the yarn is bent during the spinning of the polymer, resulting in poor spinning condition. Furthermore, since a small crimp appears, it does not become bulky. On the other hand, if the hollowness exceeds 15%, the joint surface of the two-component polymer becomes too small and the latent crimping performance is lowered, which is not preferable.
In the hollow composite short fiber of the present invention, the hollow ratio can be easily adjusted by adjusting the discharge hole shape of the composite spinneret, the molten polymer temperature, the amount of air for spinning cooling, etc.
[0010]
In the hollow composite short fiber of the present invention, for example, in the cross section of the fiber, it is desirable that the hollow portion be present in either the low viscosity polyester component or the high viscosity polyester component. For example, in the case of (1) side-side type hollow composite short fibers, either the first component or the second component is occupied more than half of the fiber cross section and more than half of the fiber cross section. Examples where the hollow portion is present in the component being used and (2) in the case of the eccentric core-sheath type hollow composite short fiber, there are examples where the hollow portion exists only in either the core portion or the sheath portion.
Such a form of the hollow composite short fiber has an effect of enlarging a spiral loop when a latent crimp is developed.
[0011]
In addition, the single fiber cross-sectional shape and hollow part cross-sectional shape of the hollow composite short fiber of this invention are not specifically limited, What is necessary is just to select suitably according to an application purpose, such as circular, a triangle, flatness, multiple leaves, and porosity.
The single fineness of the hollow composite short fiber of the present invention may be 1 to 5 dtex, preferably 1.5 to 3 dtex.
Furthermore, the cut length of the hollow composite short fiber of the present invention is usually about 3 to 150 mm, preferably about 30 to 75 mm.
[0012]
The hollow composite short fiber of the present invention is required to have a web shrinkage rate defined below as 30 to 70%, preferably 40 to 60%. Web shrinkage is a measure of latent crimp performance, and short fibers having a web shrinkage of 30% or more can sufficiently exhibit bulkiness and stretchability when made into a woven or knitted fabric. However, in a short fiber having a web shrinkage rate exceeding 70%, a large number of small spiral crimps are expressed, and although there is a stretch property, the bulkiness is impaired and the texture becomes hard. Furthermore, crimps appear in carding processes such as spinning, causing process troubles. On the other hand, if the web shrinkage rate is less than 30%, the occurrence of spiral crimp is weak and the stretchability is insufficient.
In order to adjust the web shrinkage to a range of 30 to 70%, the stretching ratio, stretching temperature conditions, and hollow ratio are set according to the intrinsic viscosity of the polyester used.
<Web shrinkage>
A short fiber having a fiber length of 51 mm before being subjected to heat shrinkage is passed through a roller card to prepare a web having a basis weight of 30 g / m ^2, a 20 cm × 20 cm sample is cut from the web, and this is heated at 120 ° C. with a hot air circulation high temperature dryer The value obtained by the following formula after allowing to stand for 10 minutes and free-shrinking.
Web shrinkage (%) = [(A−B) / A] × 100
Here, A represents the area (400 cm ² ) of the sample before heat shrinkage, and B represents the area (cm ² ) of the sample after heat shrinkage.
[0013]
The hollow composite short fiber of the present invention is usually crimped by a crimping device such as a filling crimper or a gear crimper.
Here, the crimp rate of the hollow composite short fiber of the present invention is usually 10 to 25%, preferably 15 to 20%. This crimp rate can be easily adjusted by the temperature and the number of crimps during crimping.
Here, the crimp rate is a value measured by the crimp test method of the JIS L-1015 chemical fiber staple test method.
[0014]
The hollow composite short fiber of the present invention includes, for example, a high viscosity polyester component made of polytrimethylene terephthalate having an intrinsic viscosity of 0.50 to 1.40 dl / g, and an intrinsic viscosity of 0.40 to 1.30 dl / g polytrim. A low-viscosity polyester component composed of methylene terephthalate, and a high-viscosity polyester component and a low-viscosity polyester component in which the intrinsic viscosity difference between the high-viscosity polyester component and the low-viscosity polyester component is 0.10 to 0.50 dl / g, An undrawn yarn obtained by melt spinning using a hollow side-by-side type composite melt spinning device or a hollow eccentric core-sheath type composite melt spinning device is subjected to a first stage drawing temperature of 45-60 ° C, preferably 50-60 ° C. Two-stage stretching temperature 85-120 ° C, preferably 90-110 ° C, second-stage stretching ratio 0.90-1.0 and total stretching ratio After stretching at 60 to 80%, preferably 65 to 75% of the unstretched yarn breaking ratio, after applying mechanical crimping at a temperature of 50 to 80 ° C, preferably 60 to 70 ° C, relaxation at 80 ° C or less It can be manufactured by heat treatment and cutting into short fibers.
[0015]
Further, the first stage stretching temperature (usually hot water temperature) is 45 to 60 ° C, and if it is less than 45 ° C, the stretching tension is high due to insufficient heating, and yarn breakage tends to occur. Thread breakage due to.
The second stage stretching temperature and magnification are related to the latent crimping performance and need to be stretched to 0.90 to 1.0 times at 85 to 120 ° C. Below 85 ° C, when the mechanical action is applied to the obtained short fiber, latent crimp is likely to be manifested, and when passing through a card machine in the spinning or non-woven fabric process, excessive crimp is caused in the carding process. It develops and causes defects such as nep and perforation in the obtained web. On the other hand, if it exceeds 120 ° C., the latent crimping performance decreases. If the two-stage draw ratio is made larger than 1.0 and substantial drawing is performed, many spiral crimps appear during the subsequent crimping process, making it difficult to pass through the carding process. In the second stage drawing, it is necessary to carry out a constant length or limited shrinkage heat treatment, but if the draw ratio is lower than 0.90, the fibers are excessively heat set and the latent crimping performance is lowered. A preferred magnification is 0.92 to 0.98.
Furthermore, the total draw ratio in the first-stage drawing and the second-stage drawing is 60 to 80% of the undrawn yarn breaking ratio, and if it is less than 60%, the latent crimping performance is lowered. Yarn breakage during stretching becomes difficult, making production difficult.
Furthermore, the hollow composite short fiber of the present invention is usually crimped by a crimping device such as a filling crimper or a gear crimper, and the crimping temperature during crimping at this time is 50-80. When the temperature is less than 50 ° C., it is difficult to obtain a sufficient crimp rate. On the other hand, when the temperature exceeds 80 ° C., spiral crimp that should be latent at the time of crimp processing appears, and the passability of the card process deteriorates.
Further, as the crimping processing conditions, it is preferable to set the number of crimps to 10 to 15 pieces / 25 mm for post-processing such as carding.
Further, after crimping, relaxation heat treatment is performed at 80 ° C. or lower. If it exceeds 80 ° C., spiral crimps will develop. Although there is no particular lower limit on the relaxation heat treatment temperature, the fiber before the crimping process is usually given an emulsion of a finishing oil, and is usually carried out at 40 ° C. or higher in order to remove moisture. The relaxation heat treatment time is usually 30 to 60 minutes.
The hollow composite short fiber of the present invention can be obtained by cutting to a cut length of 3 to 150 mm with a tow cutter, such as a crusher cutter or a rotary cutter, after the relaxation heat treatment.
[0016]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each item in an Example was measured with the following method.
(1) Intrinsic viscosity [η]
The measurement was performed with an Ubbelohde viscosity tube at a temperature of 35 ° C. using orthochlorophenol as a solvent.
(2) Cooling wind A wind speed when air with a wind speed of 25 ° C. and a humidity of 65% is blown at right angles to the running direction of the discharge yarn to cool it.
(3) Hollow ratio (%)
The proportion of the hollow portion in any fiber cross section was determined.
(4) Unstretched yarn breakage ratio Measured with a constant speed extension type tensile tester under the conditions of a grip width of 10 cm and a pulling speed of 100 cm / min.
(5) Crimp rate Conforms to JIS L-1015.
(6) Spinning stability Record the number of yarn breaks that occurred during the operation of the spinning machine, excluding yarn breaks caused by artificial or mechanical factors. ○, △, × depending on the number of yarn breaks per 8 hours and 1 spindle Expressed in
○: Number of yarn breaks Zero △: Number of yarn breaks 1-2 times / 8 hours / weight ×: Number of yarn breaks 3 times / 8 hours / weight (7) Web shrinkage (%)
A short fiber before heat treatment is passed through a roller card to prepare a web having a basis weight of 30 g / m ^2, a 20 cm × 20 cm sample is cut from the web, and this is put in a hot air circulating constant temperature dryer at 120 ° C. The shrinkage when free shrinking for a minute was determined by the following equation.
Web shrinkage (%) = [(A−B) / A] × 100
However, A: Area before heat treatment (cm ² )
B: Area after heat treatment (cm ² )
(8) Nonwoven fabric elastic recovery rate, short fiber before bulky heat treatment is passed through a roller card to create a web, the web is laminated and needle punched to produce a nonwoven fabric with a basis weight of about 50 g / m ² . This nonwoven fabric is heat-treated in an oven at 120 ° C. for 10 minutes, and then the bulk density of the nonwoven fabric is measured. Furthermore, the nonwoven fabric was cut into a width of 25 mm, and the elongation at break and the elastic recovery rate were obtained with a constant speed extension type tensile tester at a grip width of 100 mm and an extension speed of 100 mm / min.
Elastic recovery factor = (BC) / Bx100 (%)
(B is a value of 80% of the elongation of the nonwoven fabric, and C is the elongation relative to the sample length before measurement after the load is removed and left for 1 minute after extending to the value of B.)
(9) Comprehensive judgment Comprehensively judged from the spinning stability, the nonwoven fabric bulkiness, and the nonwoven fabric elastic recovery rate.
Good: Satisfies 8 hours of spinning, no breakage in nonwoven fabric, 15 cm ³ / g or more of nonwoven fabric, and 80% or more of elastic recovery rate of nonwoven fabric.
Defect: Does not satisfy any of the above three requirements.
[0017]
Examples 1-2 and Comparative Examples 1-6
A polymer in which the combination of the intrinsic viscosities of the first component and the second component is changed, using a composite melt spinning apparatus, at a spinning temperature of 245 ° C. to 290 ° C., component composition ratio ( A / B) (weight ratio) = 50/50 as an eccentric core-sheath type, continuous spinning was conducted for 8 hours at a discharge rate of 690 g / min and a winding speed of 1,300 m / min, and the spinning stability was investigated. Drawing was performed using the obtained undrawn yarn. Table 1 shows the spinning conditions, undrawn yarn performance, and drawing conditions at this time. Subsequent to stretching, mechanical crimping was applied at 75 ° C., followed by relaxation heat treatment at 55 ° C. for 30 minutes, and cut into 51 mm to obtain short fibers. On the other hand, after making the obtained short fiber into a web with a card | curd, the shrinkage rate and the characteristic of the nonwoven fabric were measured, and the result of Tables 1-2 was obtained. Under the conditions of Comparative Example 3, spun yarn breakage occurred frequently and it was difficult to collect undrawn yarn.
[0018]
Comparative Example 7
The results obtained in the same manner as in Example 1 except that the PCD (diameter of the inner circumference of the slit) that forms the hollow of the spinneret was increased and the hollow rate was increased by increasing the cooling air speed. It shows in Table 2.
[0019]
Comparative Example 8
Table 2 shows the results obtained in the same manner as in Example 1 except that the spinneret was changed to a solid hole number of 1,000 and the cooling air speed was slightly increased.
[0020]
[Table 1]

[0021]
[Table 2]

[0022]
【The invention's effect】
The hollow polytrimethylene terephthalate composite short fiber of the present invention has latent crimpability, is excellent in bulkiness and elastic recovery, and is suitable for obtaining nonwoven fabrics, woven and knitted fabrics, cushion materials and the like.

Claims

Polytrimethylene terephthalate polyester components having different intrinsic viscosities are composite short fibers arranged in a side-by-side type or an eccentric core-sheath type, and the intrinsic viscosity of the high-viscosity polyester component is 0.50 to 1.40 dl / g, The intrinsic viscosity of the low viscosity polyester component is 0.40 to 1.30 dl / g, the intrinsic viscosity difference between the high viscosity polyester component and the low viscosity polyester component is 0.10 to 0.50 dl / g, and the composite short fiber is The cross section has a hollow portion, the area ratio of the hollow portion to the cross section is 2 to 15%, and the web shrinkage rate defined below is 30 to 70%. Hollow polytrimethylene terephthalate composite short fiber.
<Web shrinkage>
A short fiber having a fiber length of 51 mm before being subjected to heat shrinkage is passed through a roller card to prepare a web having a basis weight of 30 g / m ^2, a 20 cm × 20 cm sample is cut from the web, and this is heated at 120 ° C. with a hot air circulation high temperature dryer The sample was allowed to stand for 10 minutes and subjected to free heat shrinkage, and the value obtained by the following formula.
Web shrinkage (%) = [(A−B) / A] × 100
Here, A represents the area (400 cm ² ) of the sample before heat shrinkage, and B represents the area (cm ² ) of the sample after heat shrinkage.

The hollow polytrimethylene terephthalate-based composite short fiber according to claim 1, wherein, in the cross section of the fiber, a hollow portion is present in one of the low-viscosity polyester component and the high-viscosity polyester component.

A method for producing a hollow composite short fiber in which polytrimethylene terephthalate polyester components having different intrinsic viscosities are arranged in a side-by-side type or an eccentric core-sheath type, wherein the intrinsic viscosity of the high-viscosity polyester component is 0.50 to 1.40 dl / G, high viscosity polyester having an intrinsic viscosity of 0.40 to 1.30 dl / g of the low viscosity polyester component and an intrinsic viscosity difference of 0.10 to 0.50 dl / g between the high viscosity polyester component and the low viscosity polyester component The hollow undrawn yarn obtained by melt spinning the component and the low-viscosity polyester component using a hollow side-by-side type composite melt spinning apparatus or a hollow eccentric core-sheath type composite melt spinning apparatus, The second stage draw temperature is 85 to 120 ° C., the second stage draw ratio is 0.90 to 1.0, and the total draw ratio is undrawn yarn breaking ratio. 3. After stretching at 60 to 80%, after applying mechanical crimping under a temperature condition of 50 to 80 [deg.] C., a relaxation heat treatment is performed at 80 [deg.] C. or less to cut into short fibers. Process for producing hollow polytrimethylene terephthalate composite short fibers.