JP2004107860A - Thermally adhesive sheath core type conjugated short fiber and non-woven fabric of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermally adhesive sheath core type short fiber capable of obtaining a non-woven fabric excellent in flame retardant property, thermal adhesion, heat resistance and soft touch, and a non-woven fabric containing the short fiber and having flame retardant property and heat resistance. <P>SOLUTION: This thermally adhesive sheath core type conjugated short fiber is characterized by arranging a low melting polyester having 25-70°C glass transition point, 80-120°C crystallization-starting point and 140-190°C melting point as the sheath part and a polyester having a main recurring unit of an alkylene terephthalate as the core part, and satisfying the following (1) to (3) at the same time. (1) The polyester of the core part contains a specific phosphorus compound by 3.0-10 mol % at the core part fiber. (2) The polyester of the core part contains the specific phosphorus compound by 2.0-6.5 mol % in the composite fiber. (3) The dry heat shrinkage of the fiber at 110°C is ≤5 %. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、Ｒ^１、Ｒ^３は炭素数１〜１８の炭化水素基、Ｒ^２はエステル形成性基、また、Ａは３価の有機残基を表す。なお、この化合物は酸無水物となっていてもよい。）
（ロ）　（イ）記載の熱接着性芯鞘型複合短繊維を含み、難燃性を示すＬＯＩ値が２５以上であることを特徴とする短繊維不織布。
【０００９】
【発明の実施の形態】
以下、本発明を詳細に説明する。
まず、鞘部を構成する低融点ポリエステルは、ガラス転移点（Ｔｇ）２５〜７０℃、結晶開始温度（Ｔｃ）８０〜１２０℃、融点（Ｔｍ）１４０〜１９０℃の結晶性のポリエステルである。
【００１０】
低融点ポリエステルのＴｇは、中でも３０〜６０℃とすることが好ましく、２５℃未満では、溶融紡糸時に単糸密着が発生し、製糸性が悪くなり、得られる不織布の風合いが低下したり、通常の二成分複合溶融紡糸では製造が困難となることもある。一方、Ｔｇが７０℃を超えると、製糸工程において高温で延伸することが必要となり、延伸による塑性変形と同時に部分的な結晶化が始まり、糸切れが発生するなど、延伸性が低下するため、好ましくない。
【００１１】
また、Ｔｃは、中でも８５〜１００℃とすることが好ましく、８０℃未満では、熱延伸工程において結晶化が進行してしまうため、次の不織布工程における熱処理工程において安定な結晶構造を再構築するのが困難となる。一方、１２０℃を超えるとＴｍも並行して高まり、熱接着加工温度を高温にする必要が生じ、経済的にも不利になる。
【００１２】
さらに、Ｔｍは、本発明の繊維において、耐熱性を示す指標となるものであり、中でも１５０〜１８０℃とすることが好ましく、１４０℃未満では、たとえ繊維化しても、高温雰囲気下で使用した場合に接着強力が低下したり変形が発生するなど、耐熱性に劣るものとなる。一方、Ｔｍが１９０℃を超えると高温熱接着処理が必要となり、経済的に好ましくないばかりか、熱処理により重合体の分解が起こりやすくなる。
【００１３】
そして、本発明の熱接着性芯鞘型複合繊維においては、鞘部を構成するポリエステルのＴｍが芯部を構成するポリエステルのＴｍより３０℃以上低いことが好ましい。鞘部のＴｍと芯部のＴｍの差が３０℃未満であると、熱接着性能が低下して、得られる不織布の強力等、機械的特性が悪くなるため、好ましくない。
【００１４】
なお、本発明におけるＴｇ、Ｔｃ及びＴｍは、示差走査型熱量計（パーキンエルマー社製ＤＳＣ７）を用い、昇温速度２０℃／分で測定するものである。
【００１５】
このような鞘部を構成する低融点ポリエステルとしては、具体的には、テレフタル酸成分、エチレングリコール成分を含有し、かつ、アジピン酸成分、脂肪族ラクトン成分、１，４−ブタンジオール成分の少なくとも一成分を含有する共重合ポリエステルであるのが好ましい。これらの共重合量を調整することにより、上記したような低融点のポリエステルとすることができる。
【００１６】
１，４−ブタンジオール成分は、全グリコール成分（エチレングリコール成分と１，４−ブタンジオール成分の合計）に対して４０〜６０モル％となるようにすることが好ましい。共重合量が４０モル％未満であると、Ｔｇ、Ｔｍ、Ｔｃが上がる傾向となり、本発明で規定する範囲外のものとなりやすく、一方、６０モル％を超えると、特にＴｇが低下しやすく、紡糸操業性が悪化しやすくなる。
【００１７】
さらに、脂肪族ラクトン成分を共重合する場合、全酸成分（テレフタル酸成分及び脂肪族ラクトン成分の合計）に対して１０〜２０モル％となるようにすることが好ましい。脂肪族ラクトン成分が１０モル％未満では結晶性はよくなるが、Ｔｍが１８０℃を超えやすく、不織布化する際、高温下での熱処理が必要となり、加工性等が悪化するため好ましくない。一方、２０モル％を超えると、Ｔｇ、Ｔｃ、Ｔｍの各温度が低くなり、紡糸時に密着が発生したり、製糸性が低下しやすい。上記した熱特性を満足しうる脂肪族ラクトン成分としては、炭素数４〜１１のラクトンが好ましく、中でも好適なラクトンとして、ε−カプロラクトンやδ−バレロラクトンが挙げられる。
【００１８】
アジピン酸成分を共重合する場合も、全酸成分（テレフタル酸成分及びアジピン酸成分の合計）に対して１０〜２０モル％となるようにすることが好ましい。これらの範囲外のものであると、上記の脂肪族ラクトン成分の場合と同様の理由で好ましくない。
【００１９】
これらの共重合成分は単独で用いても、併用してもよい。なお、脂肪族ラクトン成分とアジピン酸成分を併用する場合は、両者の合計が全酸成分に対して１０〜２０モル％となるようにすることが好ましい。
【００２０】
また、これらの低融点ポリエステルは、発明の効果を妨げない範囲であれば、酸化チタンなどの顔料、ヒンダードフェノール系化合物などの抗酸化剤その他各種添加剤を含有していてもよい。また、その特性を損なわない範囲で、イソフタル酸、フタル酸、セバシン酸、ジエチレングリコール、トリエチレングリコール等の共重合成分を少量含有していてもよい。
【００２１】
一方、芯部のポリエステルは、主たる繰り返し単位がアルキレンテレフタレートであるポリエステルであり、紡糸の操業性、原綿物性、コスト等を考慮し、ポリエチレンテレフタレート（以下、ＰＥＴと略する。）を用いることが好ましい。
【００２２】
鞘部のポリエステルは低融点ポリエステルであり、熱処理により溶融するが、芯部のポリエステルは不織布を構成する主体繊維とともに、不織布を形成する成分となる。したがって、得られる不織布の効果を損なわない範囲であれば、１，４−ブタンジオール、１，６−ヘキサンジオールなどのジオール成分、ビスフェノールＡのエチレンオキシド付加体などの芳香族ジオール成分、アジピン酸やセバシン酸などの脂肪族ジカルボン酸成分、イソフタル酸などの芳香族ジカルボン酸成分などを共重合したものでもよく、さらに、安定剤、蛍光剤、顔料、抗菌剤、消臭剤、強化剤等を添加したものでもよい。
【００２３】
そして、芯部のポリエステルは、上記（Ａ）式で示されるリン化合物を含有するものであり、芯部繊維中に３．０〜１０モル％含有し、かつ複合繊維全体としては、２．０〜６．５モル％を含有する必要がある。
【００２４】
芯部ポリエステルのリン化合物の含有量が３．０モル％未満であると、複合繊維全体のリン化合物の含有量が２．０モル％未満になることがあり、芯部ポリエステルのリン化合物の含有量が３．０モル％未満であったり、複合繊維全体のリン化合物の含有量が２．０モル％未満であると、難燃性が不十分になり、好ましくない。一方、芯部繊維中のリン化合物の含有量が１０モル％を超えたり、複合繊維中のリン化合物の含有量が６．５モル％を超えると、製糸性が悪化して繊維同士の融着が生じ、得られる不織布の風合いが悪化するため、好ましくない。
【００２５】
上記（Ａ）式で示されるリン化合物としては、以下に（Ｂ）、（Ｃ）式で示されるものが挙げられる。
【００２６】
【化３】

【００２７】
【化４】

【００２８】
さらに、本発明の熱接着性芯鞘型複合短繊維は、１１０℃での乾熱収縮率が５％以下である必要があり、さらに好ましくは３％以下である。この乾熱収縮率が５％を超える場合、特に熱接着性芯鞘型複合短繊維の使用割合が高いと、加熱接着処理時に不織布等の繊維構造体が収縮して寸法安定性が悪くなる。なお、本発明でいう乾熱収縮率とは、ＪＩＳ　Ｌ−１０１５−７−１５の方法により、４５ｇ／ｄｔｅｘの荷重で測定するものである。
【００２９】
乾熱収縮率が５％以下の熱接着性芯鞘型複合繊維を得るには、延伸工程で配向結晶させた後、鞘成分（熱接着成分）の低融点ポリエステルの結晶融点より低い温度、例えば１１０〜１４０℃のヒートドラムを用い、緊張率１．００〜１．０３倍の定張又は緊張熱処理を行えばよい。これは、鞘成分の共重合ポリエステルが明確な結晶融点を示す結晶性のポリエステルである場合のみ可能なことであり、従来の鞘成分に非晶性共重合ポリエステルを用いた熱接着性芯鞘型複合短繊維のようにＴｇ以上で軟化の始まるようなものでは不可能であった。
【００３０】
本発明の熱接着性芯鞘型複合短繊維の断面形状は特に限定するものではないが、丸断面、六葉断面などが好適に用いられる。
【００３１】
また、本発明の熱接着性芯鞘型複合短繊維を構成する芯部と鞘部の比率は、体積比（芯／鞘）として３０／７０〜７０／３０の範囲が好ましく、さらに好ましくは４０／６０〜６０／４０である。
【００３２】
芯部の体積比が３０部未満になると、不織布の風合いが損なわれやすく、一方、芯部の体積が７０部を超えると、鞘部の接着成分が少なくなり、得られる不織布の強力等の機械的特性が悪くなりやすい。
【００３３】
また、本発明の熱接着性芯鞘型複合短繊維は、捲縮を付与したものでも捲縮がないノークリンプのものでもよく、得ようとする不織布の性能や用途により適宜選択すればよい。
【００３４】
そして、繊度や繊維長は特に限定されるものではないが、得られる不織布の風合いや品位を考慮すると、捲縮を付与した短繊維の場合は、乾式不織布に好適であり、繊度１．１〜６．６ｄｔｅｘ、繊維長は２５〜７６ｍｍとすることが好ましく、ノークリンプの短繊維の場合は、湿式不織布に好適であり、繊度０．５〜５．０ｄｔｅｘ、繊維長は１〜１５ｍｍとすることが好ましい。
【００３５】
次に、本発明の熱接着性芯鞘型複合短繊維の製造方法について説明する。上記したような芯成分及び鞘成分用共重合ポリエステルを常用の複合紡糸装置を用いて複合繊維を溶融紡糸する。紡出された糸条を冷却固化した後、紡糸油剤を付与し、集束して糸条束とし、延伸した後に定張又は緊張熱処理を施す。このとき、上記したように、延伸工程で配向結晶させた後、鞘成分（熱接着成分）の低融点ポリエステルの結晶融点より低い温度、例えば１１０〜１４０℃のヒートドラムを用い、緊張率１．００〜１．０３倍の定張又は緊張熱処理を行うことが好ましい。続いて仕上げ油剤を付与し、捲縮する場合は押し込み式クリンパー等で捲縮を施し（ノークリンプとする場合は捲縮を付与することなく）、カットして短繊維とする。
【００３６】
次に、本発明の不織布について説明する。
本発明の不織布は、上記した本発明の熱接着性芯鞘型複合短繊維を含むものである。これにより、一般的に用いられている芯成分にＰＥＴ、鞘成分にイソフタル酸共重合ポリエステルを配したバインダー繊維を用いた不織布にはない難燃性と耐熱性を不織布に付与することができる。
【００３７】
本発明の不織布は、難燃性を示すＬＯＩ値が２５以上である。ＬＯＩ値は難燃性能を評価する目安のひとつであり、酸素指数と呼ばれるものである。ＬＯＩ値が２５未満であると、難燃性に乏しい不織布となる。中でもＬＯＩ値は２７以上とすることが好ましい。
【００３８】
本発明の不織布は、機械的特性や風合いを考慮すると、主体繊維と本発明の複合短繊維から構成されることが好ましいが、本発明の複合短繊維のみからなるものでもよい。したがって、主体繊維と複合短繊維の混率は、主体繊維０〜８０質量％、熱接着性複合短繊維１００〜２０質量％とすることが好ましい。熱接着性複合短繊維の混率が２０質量％未満であると、不織布を構成する繊維同士の接着交点が少なくなり、得られる不織布の機械的特性が低下しやすい。
【００３９】
主体繊維としては特に限定するものではないが、不織布の寸法安定性、耐候性、耐久性、機械的特性、リサイクル性の面から、ポリエステル系短繊維を用いることが好ましい。ポリエステル系短繊維としては、ＰＥＴからなる繊維を用いることが好ましい。そして得ようとする不織布の性能や用途に応じて、繊度や強度等を適宜選択する。
【００４０】
また、本発明の不織布は、乾式不織布であっても湿式不織布であってもよい。そして、用いる用途に応じて、目付け等を適宜選択すればよい。
【００４１】
以下、乾式不織布と湿式不織布を得る方法を説明する。
まず、乾式不織布について説明する。主体繊維と本発明の熱接着性芯鞘型複合短繊維を混綿し、又は本発明の複合短繊維のみを用い、カード機にかけウェブとする。この後、連続熱処理機で熱接着性芯鞘型複合短繊維の鞘成分のＴｍ温度より高く、鞘成分のＴｍ＋２５℃以下の温度で、熱処理を行うことによって短繊維不織布を得る。
【００４２】
湿式不織布を得る場合、主体繊維と本発明の熱接着性芯鞘型複合短繊維を混綿し、又は本発明の複合短繊維のみを用い、パルプ離解機に投入し撹拌する。得られた試料を抄紙機にて湿式不織布ウエブとする。この後、プレス機にて余分な水分を脱水した後、加圧熱処理機で熱接着性芯鞘型複合短繊維の鞘成分のＴｍ温度より高く、鞘成分のＴｍ＋２５℃以下の温度で、加圧熱処理を行うことによって短繊維不織布を得る。
【００４３】
【実施例】
次に、本発明を実施例によって具体的に説明する。なお、実施例における各特性値の測定方法及び評価方法は次の通りである。
（１）Ｔｇ、Ｔｃ及びＴｍ
前記の方法で測定した。
（２）極限粘度
フェノールと四塩化エタンとの等重量混合物を溶媒として、温度２０℃で測定した。
（３）繊度
ＪＩＳ　Ｌ−１０１５−７−５−１Ａの方法により測定した。
（４）繊維長
ＪＩＳ　Ｌ−１０１５−７−４−１Ｃの方法により測定した。
（５）操業性
紡糸、延伸の状況で判断した。
○：紡糸時の切れ糸回数が３回／日・錘以下であり、繊維の密着がなく、かつ、延伸時にローラ巻き付きの発生がない場合
×：紡糸時の切れ糸回数が３回／日・錘を超えるか、繊維の密着が発生するか、または延伸時にローラ巻き付きの発生があった場合
（６）難燃性能（ＬＯＩ値）
ＪＩＳ　Ｋ−７２０１−７２の方法により、スガ試験株式会社製ＯＮ−１型の燃焼試験機で測定した。
（７）乾熱収縮率
前記の方法で測定した。
（８）熱変形度（耐熱性）
得られた不織布を２５ｃｍ×２５ｃｍの正方形にカットし、水平に載置した内接円の直径が２０ｃｍの正方形の型枠の中央に置き、不織布の中心に２００ｇの錘をのせて１１０℃の雰囲気中に６０分間静置した。その後、室温に冷却し、錘を取り去ってから１分後の不織布中心部の垂れ下がり程度として、水平から不織布中心部が垂れ下がった長さを測定した。（値の小さいものほど変形し難いものである）
（９）不織布の引張強力
得られた不織布を用い、ＪＩＳ　Ｌ−１９１３−６−３を準用し、幅２．５ｃｍ、試料長１５ｃｍの試験片を１０個準備し、つかみ間隔１０ｃｍ、引張速度１０ｃｍ／分の条件で最大強力を個々に測定し、その平均値を得た。
○：平均値が２０００ｃＮ以上
×：平均値が２０００ｃＮ未満
（１０）不織布の風合い
得られた不織布を１５ｃｍ×１５ｃｍの正方形にカットし、パネラーによる手触りにより、風合いのソフト性を下記の基準で官能評価した。
○：良好
×：不良
【００４４】
実施例１
化学構造式（Ｂ）で示されるリン化合物を６．０モル％共重合した極限粘度０．７のポリエステル（Ｔｍ２３０℃）を芯成分に、ε−ＣＬを１５ｍｏｌ％、１，４−ブタンジオールを６０ｍｏｌ％共重合したＴｇ４０℃、Ｔｃ９４℃、Ｔｍ１５８℃の低融点ポリエステルを鞘成分に用いた。両ポリエステルを複合体積比（芯／鞘）を５０／５０とし、紡糸温度２７０℃、吐出量２０１ｇ／分、紡糸速度１１７０ｍ／分の条件で、孔数２２５個の丸型断面の複合紡糸ノズルで紡出し、未延伸糸を得た。
得られた未延伸糸を集束し、１１ｋｔｅｘの糸条束にした後、延伸倍率３．５倍、延伸温度５５℃で延伸し、１１０℃のヒートドラムで緊張率１．０１倍の緊張熱処理を施し、仕上げ油剤を０．１２質量％付与後、押し込み式クリンパーで捲縮を付与した後、切断して単糸繊度４．４ｄｔｅｘ、繊維長５１ｍｍの熱接着性芯鞘型複合短繊維を得た。
この熱接着性芯鞘型複合短繊維３０質量％と、繊度４．４ｄｔｅｘ、繊維長５１ｍｍ、強度５．０ｃＮ／ｄｔｅｘ、伸度３５％のＰＥＴからなるポリエステル繊維７０質量％を混綿し、カード機にかけウェブとした後、連続熱処理機にて１８０℃、１分の熱処理を行い、目付５０ｇ／ｍ^２のポリエステル系短繊維不織布を得た。
【００４５】
実施例２、比較例１
緊張熱処理条件を表１に記載する値に変更した（比較例１では緊張熱処理を行わなかった）以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００４６】
実施例３〜４、比較例２〜３
芯部のポリエステルのリン化合物の共重合量を表１に記載する値に変更した以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００４７】
実施例５
芯部のポリエステルと鞘部の低融点ポリエステルとの複合体積比（芯／鞘）を６０／４０に変更した以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００４８】
実施例６
芯部のポリエステルと鞘部の低融点ポリエステルとの複合体積比（芯／鞘）を４０／６０に変更した以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００４９】
実施例７〜１０、比較例５〜７
鞘部のポリエステルの共重合成分、共重合量と不織布熱処理温度を表１に記載する値に変更した以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００５０】
実施例１１
芯部のポリエステルに含有させるリン化合物を化学構造式（Ｃ）に示されるリン化合物に変更した以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００５１】
比較例４
芯部のポリエステルと鞘部の低融点ポリエステルとの複合体積比（芯／鞘）を２０／８０に変更した以外は、実施例１と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００５２】
実施例１〜１１、比較例１〜７で得られた熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布の特性値、評価結果を表１に示す。
【００５３】
【表１】

【００５４】
表１から明らかなように実施例１〜１１の熱接着性芯鞘型複合短繊維及びそれから得られた短繊維不織布（乾式不織布）は、本発明の要件を満たすものであり、操業性よく得ることができ、優れた難燃性、機械的性能、熱安定性（耐熱性）を有し、ソフトな風合いにも優れていた。
一方、比較例１の繊維は緊張熱処理を行わなかったため、乾熱収縮率が高くなり、得られた不織布は、寸法安定性が悪く、風合いにも劣るものであった。比較例２の熱接着性芯鞘型複合短繊維はリン化合物の含有量が少ないため、難燃性が十分でなかった。比較例３の熱接着性芯鞘型複合短繊維はリン化合物の含有量が多すぎたため、紡糸時に切れ糸が発生し、また、延伸時にローラ巻き付きが発生し、操業性が不良であり、得られた不織布の風合いも悪かった。比較例４の熱接着性芯鞘型複合短繊維は鞘部複合体積比が多く、複合短繊維中のリン化合物の含有量が少なかったため、得られた不織布は難燃性が不十分でまた風合いにも劣るものであった。　比較例５の熱接着性芯鞘型複合短繊維は低融点ポリエステルのＴｍ、Ｔｃともに高かったため、熱接着処理時に鞘部が溶融する温度まで加工機の温度を上げることができず、不織布を得ることができなかった。比較例６の熱接着性芯鞘型複合短繊維は鞘部のＴｇが低いため、紡糸時に繊維同士の密着が発生し、操業性が悪く、得られた不織布の風合いも悪かった。また、低融点ポリエステルのＴｍが低いため、得られた不織布は耐熱性に劣るものであった。比較例７の熱接着性芯鞘型複合短繊維は鞘部成分がイソフタル酸を共重合した非晶性の低融点ポリエステルのため、乾熱収縮率の高いものとなり、得られた不織布は寸法安定性が悪く、また、熱変形度が大きく耐熱性に劣っていた。
【００５５】
実施例１２
化学構造式（Ｂ）で示されるリン化合物を６．０モル％共重合した極限粘度０．７のポリエステル（Ｔｍ２３０℃）を芯成分に、ε−ＣＬを１５ｍｏｌ％、１，４−ブタンジオールを６０ｍｏｌ％共重合したＴｇ４０℃、Ｔｃ９４℃、Ｔｍ１５８℃の低融点ポリエステルを鞘成分に用いた。両ポリエステルを複合体積比（芯／鞘）を５０／５０とし、紡糸温度２７０℃、吐出量２０１ｇ／分、紡糸速度１１７０ｍ／分の条件で、孔数５６０個の丸型断面の複合紡糸ノズルで紡出し、未延伸糸を得た。
得られた未延伸糸を集束し、１５ｋｔｅｘの糸条束にした後、延伸倍率３．１倍、延伸温度５５℃で延伸し、１１０℃のヒートドラムで緊張率１．０１倍の緊張熱処理を施し、仕上げ油剤を０．１２質量％付与後、捲縮を施すことなく、切断して単糸繊度１．１ｄｔｅｘ、繊維長５ｍｍの熱接着性芯鞘型複合短繊維（ノークリンプショートカット繊維）を得た。
この熱接着性芯鞘型複合短繊維３０質量％と、繊度１．１ｄｔｅｘ、繊維長５ｍｍ、強度５．０ｃＮ／ｄｔｅｘ、伸度３５％のＰＥＴからなるポリエステル繊維７０質量％を混合し、パルプ離解機（熊谷理機工業製）に投入し、３０００ｒｐｍにて１分間撹拌した。その後、得られた試料を抄紙機（熊谷理機工業製角型シートマシーン）にて湿式不織布ウエブとした。抄紙した湿式不織布ウエブを、プレス機（熊谷理機製）にて余分な水分を脱水した後、表面温度１８０℃、熱処理時間１００秒、プレス線圧０．１ＭＰａの条件の回転乾燥機（熊谷理機製：卓上型ヤンキードライヤー）にて熱処理し、目付４０ｇ／ｍ^２のポリエステル系短繊維不織布を得た。
【００５６】
実施例１３、比較例８
緊張熱処理条件を表２に記載する値に変更した（比較例８では緊張熱処理を行わなかった）以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維（ノークリンプショートカット繊維）とポリエステル系短繊維不織布を得た。
【００５７】
実施例１４〜１５、比較例９〜１０
芯部のポリエステルのリン化合物の共重合量を表２に記載する値に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００５８】
実施例１６
芯部のポリエステルと鞘部の低融点ポリエステルとの複合体積比（芯／鞘）を６０／４０に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００５９】
実施例１７
芯部のポリエステルと鞘部の低融点ポリエステルとの複合体積比（芯／鞘）を４０／６０に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００６０】
実施例１８〜２１、比較例１２〜１４
鞘部のポリエステルの共重合成分、共重合量と不織布熱処理温度を表２に記載する値に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００６１】
実施例２２
芯部のポリエステルに含有させるリン化合物を化学構造式（Ｃ）に示されるリン化合物に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系湿式短繊維不織布を得た。
【００６２】
比較例１１
芯部のポリエステルと鞘部の低融点ポリエステルとの複合体積比（芯／鞘）を２０／８０に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００６３】
実施例２３〜２４
単糸繊度を表２に記載する値に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布を得た。
【００６４】
実施例２５〜２６
繊維長を表２に記載する値に変更した以外は、実施例１２と同様な方法で熱接着性芯鞘
型複合短繊維とポリエステル系短繊維不織布を得た。
【００６５】
実施例１２〜２６、比較例８〜１８で得られた熱接着性芯鞘型複合短繊維とポリエステル系短繊維不織布の特性値、評価結果を表２に示す。
【００６６】
【表２】

【００６７】
表２から明らかなように実施例１２〜２６の熱接着性芯鞘型複合短繊維（ノークリンプショートカット繊維）及びそれから得られた短繊維不織布（湿式不織布）は、本発明の要件を満たすものであり、操業性よく得ることができ、優れた難燃性、機械的性能、熱安定性（耐熱性）を有し、ソフトな風合いにも優れていた。
一方、比較例８の熱接着性芯鞘型複合短繊維は緊張熱処理を行わなかったため、乾熱収縮率が高くなり、得られた不織布は、寸法安定性が悪く、風合いにも劣るものであった。比較例９の熱接着性芯鞘型複合短繊維はリン化合物の含有量が少ないため、難燃性が十分でなかった。比較例１０の熱接着性芯鞘型複合短繊維はリン化合物の含有量が多すぎたため、紡糸時に切れ糸が発生し、また、延伸時にローラ巻き付きが発生し、操業性が不良であり、得られた不織布の風合いも悪かった。比較例１１の熱接着性芯鞘型複合短繊維は鞘部複合体積比が多く、複合短繊維中のリン化合物の含有量が少なかったため、得られた不織布は難燃性が不十分でまた風合いにも劣るものであった。　比較例１２の熱接着性芯鞘型複合短繊維は低融点ポリエステルのＴｍ、Ｔｃともに高かったため、熱接着処理時に鞘部が溶融する温度まで加工機の温度を上げることができず、不織布を得ることができなかった。比較例１３の熱接着性芯鞘型複合短繊維は鞘部のＴｇが低いため、紡糸時に繊維同士の密着が発生し、操業性が悪く、得られた不織布の風合いも悪かった。また、低融点ポリエステルのＴｍが低いため、得られた不織布は耐熱性に劣るものであった。比較例１４の熱接着性芯鞘型複合短繊維は鞘部成分がイソフタル酸を共重合した非晶性の低融点ポリエステルのため、乾熱収縮率の高いものとなり、得られた不織布は寸法安定性が悪く、また、熱変形度が大きく耐熱性に劣っていた。
【００６８】
【発明の効果】
本発明の熱接着性芯鞘型複合短繊維は、芯部と鞘部のポリエステルの組成、リン化合物の共重合量を規定することで、優れた難燃性、熱接着性、耐熱性を有し、操業性よく得ることができる。そして、本発明の熱接着性芯鞘型複合短繊維からなる不織布は、難燃性、機械的特性、耐熱性、ソフトな風合いに優れており、難燃性能と耐熱性が要求される分野（例：家具材、壁材等の建材、自動車内装材等）に広く利用することが可能となる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a composite fiber having a low melting point component disposed in a sheath portion and a flame retardant component in a core portion, the sheath portion being melted by heat treatment, and suitable for obtaining a dry nonwoven fabric, a wet nonwoven fabric, or the like. The present invention relates to a heat-adhesive core-sheath type composite short fiber and a short fiber nonwoven fabric containing the fiber and having excellent flame retardancy, mechanical properties and heat resistance.
[0002]
[Prior art]
Synthetic fibers, especially polyester fibers, have become indispensable as clothing and industrial materials due to their excellent dimensional stability, weather resistance, mechanical properties, durability, and recyclability, etc. Polyester fibers are often used.
[0003]
Conventional nonwoven fabrics made of polyester short fibers use heat-adhesive short fibers to thermally bond the main fibers. Generally, polyethylene terephthalate (PET) is used for the core component and isophthalic acid is used for the sheath component. A core-sheath type composite short fiber having a copolymerized low melting point polymer is used (for example, see Patent Document 1).
[0004]
In nonwoven fabrics made of such polyester staple fibers, flame-retardant resins are used in fields where flame retardancy is required (eg, furniture, building materials such as wall materials, automobile interior materials, etc.). Is given by post-processing, so that the process becomes complicated and the cost is increased, and there is a demand for flame-retardant core-sheath composite short fibers.
[0005]
Further, the low melting point polymer obtained by copolymerizing isophthalic acid as described above is amorphous, does not show a clear melting point, and begins to soften when the temperature exceeds the glass transition point. Therefore, the fibers cannot be heat-set at the time of production, and shrinkage occurs during the heat bonding treatment. Therefore, when the use ratio of this fiber in a product such as a nonwoven fabric is large, the dimensional stability of the product such as the obtained nonwoven fabric is deteriorated, and when used in a high-temperature atmosphere, the adhesive strength is reduced or deformation is caused. There was a problem that occurred.
[0006]
[Patent Document 1]
JP-A-9-119019
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, and has excellent flame retardancy and adhesiveness that cannot be obtained by the conventional technology, and can impart flame retardancy to the obtained nonwoven fabric without performing post-processing. A heat-adhesive core-sheath type composite staple fiber that can produce a non-woven fabric that is excellent in heat resistance without shrinkage at the time of heating and bonding, even when used in a high temperature atmosphere, without lowering of adhesive strength and deformation. It is what we are going to offer.
[0008]
[Means for Solving the Problems]
The present inventors have reached the present invention as a result of intensive studies to solve the above problems.
That is, the present invention has the following (a) and (b).
(A) A core having a low melting point polyester having a glass transition point of 25 to 70 ° C., a crystallization onset temperature of 80 to 120 ° C. and a melting point of 140 to 190 ° C. in a sheath portion, and a polyester in which a main repeating unit is alkylene terephthalate in a core portion. A heat-adhesive core-sheath composite short fiber, which is a sheath-type composite fiber, which satisfies the following (1) to (3) at the same time.
(1) The polyester at the core contains a phosphorus compound represented by the following formula (A), and the core fiber contains 3.0 to 10 mol%.
(2) The polyester at the core contains a phosphorus compound represented by the following formula (A), and contains 2.0 to 6.5 mol% in the composite fiber.
(3) The dry heat shrinkage at 110 ° C. is 5% or less.
Embedded image

(Where R ¹ , R ³ Is a hydrocarbon group having 1 to 18 carbon atoms, R ² Represents an ester-forming group, and A represents a trivalent organic residue. In addition, this compound may be an acid anhydride. )
(B) A short fiber nonwoven fabric comprising the heat-adhesive core-sheath composite short fiber according to (a) and having a flame retardancy LOI value of 25 or more.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
First, the low-melting polyester constituting the sheath is a crystalline polyester having a glass transition point (Tg) of 25 to 70 ° C, a crystallization onset temperature (Tc) of 80 to 120 ° C, and a melting point (Tm) of 140 to 190 ° C.
[0010]
The Tg of the low-melting polyester is preferably 30 to 60 ° C., and if it is less than 25 ° C., single yarn adhesion occurs during melt spinning, the spinning properties are deteriorated, and the texture of the obtained nonwoven fabric is reduced. In some cases, production may be difficult with the two-component composite melt spinning. On the other hand, when the Tg exceeds 70 ° C., it is necessary to perform stretching at a high temperature in the yarn-making process, and partial crystallization starts simultaneously with plastic deformation due to stretching, and thread breakage occurs. Not preferred.
[0011]
Further, Tc is particularly preferably 85 to 100 ° C., and if it is lower than 80 ° C., crystallization proceeds in the hot stretching step, so that a stable crystal structure is reconstructed in the heat treatment step in the next nonwoven fabric step. It becomes difficult. On the other hand, when the temperature exceeds 120 ° C., Tm also increases in parallel, and it is necessary to raise the temperature of the thermal bonding process, which is economically disadvantageous.
[0012]
Further, Tm is an index indicating heat resistance in the fiber of the present invention. In particular, the temperature is preferably set to 150 to 180 ° C. In this case, the heat resistance is inferior, for example, the adhesive strength is reduced or deformation occurs. On the other hand, when Tm exceeds 190 ° C., a high-temperature heat bonding treatment is required, which is not economically preferable, and the polymer is easily decomposed by the heat treatment.
[0013]
In the heat-adhesive core-sheath composite fiber of the present invention, it is preferable that the Tm of the polyester constituting the sheath is lower by at least 30 ° C. than the Tm of the polyester constituting the core. If the difference between the Tm of the sheath portion and the Tm of the core portion is less than 30 ° C., the thermal bonding performance is reduced, and the mechanical properties such as the strength of the obtained nonwoven fabric are deteriorated.
[0014]
In the present invention, Tg, Tc and Tm are measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC7 manufactured by PerkinElmer).
[0015]
As the low-melting polyester constituting such a sheath, specifically, a terephthalic acid component, an ethylene glycol component, and at least an adipic acid component, an aliphatic lactone component, and a 1,4-butanediol component. It is preferably a copolyester containing one component. By adjusting the amount of these copolymers, a polyester having a low melting point as described above can be obtained.
[0016]
It is preferable that the 1,4-butanediol component be 40 to 60 mol% with respect to all glycol components (the total of the ethylene glycol component and the 1,4-butanediol component). When the copolymerization amount is less than 40 mol%, Tg, Tm, and Tc tend to increase, and tend to fall outside the range specified in the present invention. On the other hand, when it exceeds 60 mol%, Tg tends to decrease, Spinning operability is likely to deteriorate.
[0017]
Further, when the aliphatic lactone component is copolymerized, it is preferable that the amount is 10 to 20 mol% with respect to all the acid components (total of the terephthalic acid component and the aliphatic lactone component). When the aliphatic lactone component is less than 10 mol%, the crystallinity is improved, but the Tm easily exceeds 180 ° C., and when a nonwoven fabric is formed, heat treatment at a high temperature is required, and the workability and the like are unfavorably deteriorated. On the other hand, if it exceeds 20 mol%, the respective temperatures of Tg, Tc, and Tm become low, so that adhesion occurs at the time of spinning and the spinnability tends to deteriorate. As the aliphatic lactone component capable of satisfying the above-mentioned thermal characteristics, a lactone having 4 to 11 carbon atoms is preferable. Among them, ε-caprolactone and δ-valerolactone are preferable.
[0018]
Also in the case where the adipic acid component is copolymerized, it is preferable that the amount be 10 to 20 mol% with respect to all the acid components (total of the terephthalic acid component and the adipic acid component). Outside of these ranges is not preferred for the same reasons as in the case of the aliphatic lactone component.
[0019]
These copolymer components may be used alone or in combination. When the aliphatic lactone component and the adipic acid component are used in combination, it is preferable that the total of both components is 10 to 20 mol% based on the total acid components.
[0020]
Further, these low-melting polyesters may contain a pigment such as titanium oxide, an antioxidant such as a hindered phenol compound and other various additives as long as the effects of the invention are not impaired. Further, a small amount of a copolymer component such as isophthalic acid, phthalic acid, sebacic acid, diethylene glycol, and triethylene glycol may be contained as long as the properties are not impaired.
[0021]
On the other hand, the polyester at the core is a polyester whose main repeating unit is alkylene terephthalate, and it is preferable to use polyethylene terephthalate (hereinafter abbreviated as PET) in consideration of operability of spinning, physical properties of raw cotton, cost, and the like. .
[0022]
The polyester in the sheath is a low-melting polyester and is melted by heat treatment, but the polyester in the core is a component forming the nonwoven fabric together with the main fibers constituting the nonwoven fabric. Therefore, diol components such as 1,4-butanediol and 1,6-hexanediol, aromatic diol components such as an ethylene oxide adduct of bisphenol A, adipic acid and sebacin are within a range that does not impair the effect of the obtained nonwoven fabric. An aliphatic dicarboxylic acid component such as an acid, an aromatic dicarboxylic acid component such as isophthalic acid may be copolymerized, and a stabilizer, a fluorescent agent, a pigment, an antibacterial agent, a deodorant, a reinforcing agent, and the like may be added. It may be something.
[0023]
The polyester in the core contains the phosphorus compound represented by the above formula (A), contains 3.0 to 10 mol% in the core fiber, and has a total of 2.0% in the composite fiber. ６6.5 mol%.
[0024]
When the content of the phosphorus compound in the core polyester is less than 3.0 mol%, the content of the phosphorus compound in the entire conjugate fiber may be less than 2.0 mol%, and the content of the phosphorus compound in the core polyester may be reduced. When the amount is less than 3.0 mol% or the content of the phosphorus compound in the entire conjugate fiber is less than 2.0 mol%, the flame retardancy becomes insufficient, which is not preferable. On the other hand, if the content of the phosphorus compound in the core fiber exceeds 10 mol% or the content of the phosphorus compound in the composite fiber exceeds 6.5 mol%, the spinnability deteriorates and the fibers are fused. This is undesirable because the texture of the resulting nonwoven fabric deteriorates.
[0025]
Examples of the phosphorus compound represented by the formula (A) include those represented by the following formulas (B) and (C).
[0026]
Embedded image

[0027]
Embedded image

[0028]
Further, the heat-adhesive core-sheath conjugate short fibers of the present invention must have a dry heat shrinkage at 110 ° C. of 5% or less, more preferably 3% or less. When the dry heat shrinkage exceeds 5%, particularly when the use ratio of the heat-adhesive core-sheath composite short fibers is high, the fibrous structure such as a nonwoven fabric shrinks during the heat bonding treatment, and the dimensional stability deteriorates. In addition, the dry heat shrinkage rate in the present invention is measured by a method of JIS L-1015-7-15 at a load of 45 g / dtex.
[0029]
In order to obtain a heat-adhesive core-sheath type composite fiber having a dry heat shrinkage of 5% or less, after orientation-crystallizing in the stretching step, a temperature lower than the crystal melting point of the low-melting polyester of the sheath component (heat-adhesive component), for example, Using a heat drum at 110 to 140 ° C., a tension or tension heat treatment at a tension rate of 1.00 to 1.03 times may be performed. This is possible only when the copolyester of the sheath component is a crystalline polyester showing a clear crystal melting point, and is a heat-adhesive core-sheath type using an amorphous copolyester as the conventional sheath component. It was not possible with a material such as a conjugate short fiber whose softening started at Tg or more.
[0030]
The cross-sectional shape of the heat-adhesive core-sheath conjugate short fiber of the present invention is not particularly limited, but a round cross section, a six-leaf cross section, or the like is preferably used.
[0031]
Further, the ratio of the core part and the sheath part constituting the heat-adhesive core-sheath type composite short fiber of the present invention is preferably 30/70 to 70/30 as a volume ratio (core / sheath), and more preferably 40/70. / 60 to 60/40.
[0032]
If the volume ratio of the core is less than 30 parts, the texture of the nonwoven fabric tends to be impaired, while if the volume of the core exceeds 70 parts, the adhesive component of the sheath decreases, and the strength of the resulting nonwoven fabric is reduced. Characteristic tends to deteriorate.
[0033]
Further, the heat-adhesive core-sheath type conjugate short fiber of the present invention may be a crimped or non-crimped crimped fiber, and may be appropriately selected depending on the performance and application of the nonwoven fabric to be obtained.
[0034]
The fineness and fiber length are not particularly limited, but in consideration of the texture and quality of the obtained nonwoven fabric, in the case of crimped short fibers, they are suitable for dry nonwoven fabrics and have a fineness of 1.1 to 1.1. 6.6 dtex, the fiber length is preferably 25 to 76 mm, and in the case of short fibers of no crimp, it is suitable for wet nonwoven fabric, and the fineness is 0.5 to 5.0 dtex, and the fiber length is 1 to 15 mm. preferable.
[0035]
Next, a method for producing the heat-adhesive core-sheath composite short fiber of the present invention will be described. The composite fiber for the core component and the sheath component as described above is melt-spun using a conventional composite spinning apparatus. After the spun yarn is cooled and solidified, a spinning oil agent is applied, bundled into a bundle of yarns, and stretched and then subjected to constant tension or tension heat treatment. At this time, as described above, after the oriented crystal is formed in the stretching step, a tension lower than the crystal melting point of the low-melting polyester of the sheath component (heat bonding component), for example, 110 to 140 ° C. is used, and the tension ratio is set to 1. It is preferable to carry out a constant tension or tension heat treatment of 00 to 1.03 times. Subsequently, a finishing oil is applied, and when crimping is performed, crimping is performed by a press-type crimper or the like (when no crimping is performed, no crimping is applied), and cut into short fibers.
[0036]
Next, the nonwoven fabric of the present invention will be described.
The nonwoven fabric of the present invention contains the above-mentioned heat-adhesive core-sheath composite short fibers of the present invention. This makes it possible to provide the nonwoven fabric with flame retardancy and heat resistance that cannot be obtained with a nonwoven fabric using a binder fiber in which a commonly used core component is PET and a sheath component is isophthalic acid copolymerized polyester.
[0037]
The nonwoven fabric of the present invention has an LOI value of 25 or more indicating flame retardancy. The LOI value is one of the criteria for evaluating the flame retardancy, and is called an oxygen index. When the LOI value is less than 25, the nonwoven fabric has poor flame retardancy. In particular, the LOI value is preferably 27 or more.
[0038]
The nonwoven fabric of the present invention is preferably composed of the main fiber and the conjugated staple fiber of the present invention in consideration of mechanical properties and texture, but may be composed of only the conjugated staple fiber of the present invention. Therefore, the mixing ratio of the main fiber and the conjugate short fiber is preferably 0 to 80% by mass of the main fiber and 100 to 20% by mass of the heat-adhesive conjugate short fiber. When the mixing ratio of the heat-adhesive conjugate short fibers is less than 20% by mass, the number of bonding intersections between the fibers constituting the nonwoven fabric decreases, and the mechanical properties of the obtained nonwoven fabric tend to deteriorate.
[0039]
The main fiber is not particularly limited, but polyester short fibers are preferably used in view of dimensional stability, weather resistance, durability, mechanical properties, and recyclability of the nonwoven fabric. As the polyester-based short fiber, it is preferable to use a fiber made of PET. The fineness, strength and the like are appropriately selected according to the performance and use of the nonwoven fabric to be obtained.
[0040]
The nonwoven fabric of the present invention may be a dry nonwoven fabric or a wet nonwoven fabric. Then, the basis weight and the like may be appropriately selected depending on the use to be used.
[0041]
Hereinafter, a method for obtaining a dry nonwoven fabric and a wet nonwoven fabric will be described.
First, the dry nonwoven fabric will be described. The main fiber and the heat-adhesive core-sheath type composite short fiber of the present invention are mixed, or only the composite short fiber of the present invention is used, and a web is formed on a carding machine. Thereafter, heat treatment is performed by a continuous heat treatment machine at a temperature higher than the Tm temperature of the sheath component of the heat-adhesive core-sheath composite short fiber and at a temperature equal to or lower than Tm + 25 ° C. of the sheath component to obtain a short fiber nonwoven fabric.
[0042]
In the case of obtaining a wet nonwoven fabric, the main fiber and the heat-adhesive core-sheath composite short fiber of the present invention are mixed, or only the composite short fiber of the present invention is used and charged into a pulp disintegrator and stirred. The obtained sample is made into a wet nonwoven web by a paper machine. Thereafter, excess water is dehydrated by a press machine, and then pressurized by a pressure heat treatment machine at a temperature higher than the Tm temperature of the sheath component of the heat-adhesive core-sheath composite short fiber and at a temperature equal to or lower than Tm + 25 ° C. A short fiber nonwoven fabric is obtained by heat treatment.
[0043]
【Example】
Next, the present invention will be described specifically with reference to examples. The measuring method and evaluation method of each characteristic value in the examples are as follows.
(1) Tg, Tc and Tm
It was measured by the method described above.
(2) Intrinsic viscosity
The measurement was carried out at a temperature of 20 ° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent.
(3) Fineness
It measured by the method of JIS L-1015-7-5-1A.
(4) Fiber length
It measured by the method of JIS L-1015-7-4-1C.
(5) Operability
Judgment was made based on spinning and drawing conditions.
：: When the number of cuts during spinning is 3 times / day / weight or less, there is no close contact of the fibers, and there is no winding of the roller during stretching.
X: When the number of cut yarns during spinning exceeds 3 times / day / weight, when fibers adhere to each other, or when rolls are wound during stretching.
(6) Flame retardant performance (LOI value)
According to the method of JIS K-7201-72, it was measured with an ON-1 type combustion tester manufactured by Suga Test Co., Ltd.
(7) Dry heat shrinkage
It was measured by the method described above.
(8) Thermal deformation (heat resistance)
The obtained non-woven fabric is cut into a 25 cm × 25 cm square, placed in the center of a horizontally placed inscribed circle having a diameter of 20 cm in a square form, and a 200 g weight is placed on the center of the non-woven fabric at 110 ° C. atmosphere. And allowed to stand for 60 minutes. Thereafter, the temperature was cooled to room temperature, and the length of the central portion of the nonwoven fabric hanging down from the horizontal was measured as the degree of sagging of the central portion of the nonwoven fabric one minute after removing the weight. (The smaller the value, the more difficult it is to deform)
(9) Tensile strength of non-woven fabric
Using the obtained nonwoven fabric, JIS L-1913-6-3 was applied mutatis mutandis, and 10 test pieces having a width of 2.5 cm and a sample length of 15 cm were prepared, and the maximum strength was obtained at a gripping interval of 10 cm and a pulling speed of 10 cm / min. Was measured individually, and the average value was obtained.
：: Average value is 2,000 cN or more
×: Average value is less than 2000 cN
(10) Texture of non-woven fabric
The obtained nonwoven fabric was cut into a square of 15 cm × 15 cm, and the softness of the texture was organoleptically evaluated by the touch of a panelist according to the following criteria.
：: good
×: defective
[0044]
Example 1
As a core component, a polyester having an intrinsic viscosity of 0.7 (Tm of 230 ° C.) obtained by copolymerizing a phosphorus compound represented by the chemical structural formula (B) with 6.0 mol%, 15 mol% of ε-CL and 1,4-butanediol are used. A low-melting polyester having a Tg of 40 ° C., a Tc of 94 ° C., and a Tm of 158 ° C. copolymerized with 60 mol% was used as a sheath component. The composite volume ratio (core / sheath) of both polyesters is 50/50, the spinning temperature is 270 ° C., the discharge rate is 201 g / min, and the spinning speed is 1170 m / min. It was spun to obtain an undrawn yarn.
The obtained undrawn yarn is bundled to form a 11 ktex yarn bundle, and then drawn at a draw ratio of 3.5 times and a drawing temperature of 55 ° C, and subjected to a tension heat treatment at a tension rate of 1.01 times with a 110 ° C heat drum. After applying 0.12% by mass of the finishing oil, crimping was performed with a push-in crimper and then cut to obtain a heat-adhesive core-sheath type composite short fiber having a single yarn fineness of 4.4 dtex and a fiber length of 51 mm. .
30% by mass of this heat-adhesive core-sheath type composite short fiber and 70% by mass of polyester fiber made of PET having a fineness of 4.4 dtex, a fiber length of 51 mm, a strength of 5.0 cN / dtex and an elongation of 35% are mixed. And then heat treated at 180 ° C. for 1 minute with a continuous heat treatment machine to obtain a basis weight of 50 g / m 2. ² Was obtained.
[0045]
Example 2, Comparative Example 1
Except that the tension heat treatment conditions were changed to the values shown in Table 1 (no tension heat treatment was performed in Comparative Example 1), the heat-adhesive core-sheath type composite short fibers and polyester short fibers were produced in the same manner as in Example 1. A non-woven fabric was obtained.
[0046]
Examples 3-4, Comparative Examples 2-3
Except that the copolymerization amount of the phosphorus compound of the polyester in the core was changed to the value shown in Table 1, a thermoadhesive core-sheath type composite short fiber and a polyester-based short fiber non-woven fabric were obtained in the same manner as in Example 1. .
[0047]
Example 5
Except that the composite volume ratio (core / sheath) of the polyester of the core and the low-melting polyester of the sheath was changed to 60/40, the heat-adhesive core-sheath type composite short fiber and polyester were produced in the same manner as in Example 1. A system short fiber nonwoven fabric was obtained.
[0048]
Example 6
Except that the composite volume ratio (core / sheath) of the polyester of the core and the low-melting polyester of the sheath was changed to 40/60, the heat-adhesive core-sheath type composite staple fiber and the polyester were produced in the same manner as in Example 1. A system short fiber nonwoven fabric was obtained.
[0049]
Examples 7 to 10, Comparative Examples 5 to 7
Except that the copolymerization component of the sheath, the amount of copolymerization of the polyester, and the heat treatment temperature of the nonwoven fabric were changed to the values shown in Table 1, the heat-adhesive core-sheath type composite staple fiber and polyester-based short fiber were produced in the same manner as in Example 1. A fibrous nonwoven fabric was obtained.
[0050]
Example 11
Except that the phosphorus compound contained in the core polyester was changed to the phosphorus compound represented by the chemical structural formula (C), the heat-adhesive core-sheath type composite short fiber and the polyester short fiber non-woven fabric were produced in the same manner as in Example 1. Got.
[0051]
Comparative Example 4
Except that the composite volume ratio (core / sheath) of the polyester of the core and the low-melting polyester of the sheath was changed to 20/80, the heat-adhesive core-sheath type composite short fiber and the polyester were produced in the same manner as in Example 1. A system short fiber nonwoven fabric was obtained.
[0052]
Table 1 shows the characteristic values and the evaluation results of the heat-adhesive core-sheath composite short fibers and the polyester-based short fiber nonwoven fabric obtained in Examples 1 to 11 and Comparative Examples 1 to 7.
[0053]
[Table 1]

[0054]
As is clear from Table 1, the heat-adhesive core-sheath composite short fibers of Examples 1 to 11 and the short-fiber nonwoven fabric (dry nonwoven fabric) obtained therefrom satisfy the requirements of the present invention and can be easily operated. It had excellent flame retardancy, mechanical performance, thermal stability (heat resistance) and excellent soft texture.
On the other hand, since the fiber of Comparative Example 1 was not subjected to the tension heat treatment, the dry heat shrinkage was high, and the obtained nonwoven fabric had poor dimensional stability and poor texture. The heat-adhesive core-sheath type conjugate short fibers of Comparative Example 2 had a low content of the phosphorus compound, and thus did not have sufficient flame retardancy. Since the heat-adhesive core-sheath type conjugate short fiber of Comparative Example 3 contained too much phosphorus compound, cut yarn was generated at the time of spinning, and roll wrap was generated at the time of stretching, resulting in poor operability. The texture of the obtained nonwoven fabric was also bad. Since the heat-adhesive core-sheath type composite short fiber of Comparative Example 4 had a large composite volume ratio of the sheath portion and a low content of the phosphorus compound in the composite short fiber, the obtained nonwoven fabric had insufficient flame retardancy and texture. Was also inferior. Since the Tm and Tc of the low-melting polyester were both high in the heat-bondable core-sheath type composite short fiber of Comparative Example 5, the temperature of the processing machine could not be raised to the temperature at which the sheath melted during the heat bonding treatment, and a nonwoven fabric was obtained. I couldn't do that. The heat-adhesive core-sheath type conjugate short fiber of Comparative Example 6 had a low Tg in the sheath portion, so that the fibers adhered to each other at the time of spinning, the operability was poor, and the texture of the obtained nonwoven fabric was poor. Further, since the Tm of the low melting point polyester was low, the obtained nonwoven fabric was inferior in heat resistance. The heat-adhesive core-sheath type composite short fiber of Comparative Example 7 has a high dry heat shrinkage because the sheath component is an amorphous low-melting polyester obtained by copolymerizing isophthalic acid, and the obtained nonwoven fabric is dimensionally stable. The heat resistance was poor, and the heat deformation was large and the heat resistance was poor.
[0055]
Example 12
As a core component, a polyester having an intrinsic viscosity of 0.7 (Tm of 230 ° C.) obtained by copolymerizing a phosphorus compound represented by the chemical structural formula (B) with 6.0 mol%, 15 mol% of ε-CL and 1,4-butanediol are used. A low-melting polyester having a Tg of 40 ° C., a Tc of 94 ° C., and a Tm of 158 ° C. copolymerized with 60 mol% was used as a sheath component. The composite volume ratio (core / sheath) of both polyesters is 50/50, the spinning temperature is 270 ° C., the discharge rate is 201 g / min, and the spinning speed is 1170 m / min. It was spun to obtain an undrawn yarn.
The obtained undrawn yarn is bundled to form a 15 ktex yarn bundle, and then drawn at a draw ratio of 3.1 times at a drawing temperature of 55 ° C., and subjected to a tension heat treatment at a tension rate of 1.01 times with a 110 ° C. heat drum. After applying 0.12% by mass of the finishing oil, the composition is cut without crimping to obtain a heat-adhesive core-sheath composite short fiber (no crimp shortcut fiber) having a single yarn fineness of 1.1 dtex and a fiber length of 5 mm. Obtained.
30% by mass of this heat-adhesive core-sheath composite short fiber and 70% by mass of polyester fiber made of PET having a fineness of 1.1 dtex, a fiber length of 5 mm, a strength of 5.0 cN / dtex and an elongation of 35% are mixed, and pulp disintegration is performed. It was charged into a machine (manufactured by Kumagaya Riki Kogyo) and stirred at 3000 rpm for 1 minute. Then, the obtained sample was made into a wet nonwoven fabric web with a paper machine (square sheet machine manufactured by Kumagai Riki Kogyo). After dehydrating excess moisture from the wet nonwoven web made by a press machine (manufactured by Kumagai Riki), a rotary dryer (manufactured by Kumagaya Riki) having a surface temperature of 180 ° C., a heat treatment time of 100 seconds, and a linear pressure of 0.1 MPa is used. : Table type Yankee dryer) heat-treated with a basis weight of 40 g / m ² Was obtained.
[0056]
Example 13 and Comparative Example 8
Except that the tension heat treatment conditions were changed to the values shown in Table 2 (no tension heat treatment was performed in Comparative Example 8), the heat-adhesive core-sheath type composite staple fiber (No crimp shortcut fiber) was produced in the same manner as in Example 12. ) And a polyester-based short fiber non-woven fabric.
[0057]
Examples 14 to 15, Comparative Examples 9 to 10
Except that the copolymerization amount of the phosphorus compound of the polyester in the core was changed to the value shown in Table 2, a thermoadhesive core-sheath type composite short fiber and a polyester-based short fiber nonwoven fabric were obtained in the same manner as in Example 12. .
[0058]
Example 16
Except that the composite volume ratio (core / sheath) of the polyester of the core and the low-melting polyester of the sheath was changed to 60/40, the heat-adhesive core-sheath type composite short fiber and the polyester were produced in the same manner as in Example 12. A system short fiber nonwoven fabric was obtained.
[0059]
Example 17
Except that the composite volume ratio (core / sheath) of the polyester of the core and the low-melting polyester of the sheath was changed to 40/60, the heat-adhesive core-sheath type composite short fiber and the polyester were produced in the same manner as in Example 12. A system short fiber nonwoven fabric was obtained.
[0060]
Examples 18 to 21, Comparative Examples 12 to 14
Except that the copolymerization component of the sheath portion, the copolymerization amount of the polyester and the non-woven fabric heat treatment temperature were changed to the values shown in Table 2, the heat-adhesive core-sheath type composite staple fiber and polyester staple fiber were prepared in the same manner as in Example 12. A fibrous nonwoven fabric was obtained.
[0061]
Example 22
Except that the phosphorus compound contained in the polyester of the core was changed to the phosphorus compound represented by the chemical structural formula (C), the heat-adhesive core-sheath composite short fiber and the polyester wet short fiber were obtained in the same manner as in Example 12. A non-woven fabric was obtained.
[0062]
Comparative Example 11
Except that the composite volume ratio (core / sheath) of the polyester at the core and the low-melting polyester at the sheath was changed to 20/80, the heat-adhesive core-sheath type composite short fiber and polyester were produced in the same manner as in Example 12. A system short fiber nonwoven fabric was obtained.
[0063]
Examples 23 to 24
Except that the single yarn fineness was changed to the value shown in Table 2, a thermoadhesive core-sheath composite short fiber and a polyester short fiber nonwoven fabric were obtained in the same manner as in Example 12.
[0064]
Examples 25 to 26
Except that the fiber length was changed to the value described in Table 2, a heat-adhesive core / sheath was obtained in the same manner as in Example 12.
A conjugate short fiber and a polyester short fiber nonwoven fabric were obtained.
[0065]
Table 2 shows the characteristic values and the evaluation results of the heat-adhesive core-sheath composite short fibers and the polyester-based short fiber nonwoven fabric obtained in Examples 12 to 26 and Comparative Examples 8 to 18.
[0066]
[Table 2]

[0067]
As is clear from Table 2, the heat-adhesive core-sheath composite short fibers (no crimp shortcut fibers) of Examples 12 to 26 and the short fiber nonwoven fabric (wet nonwoven fabric) obtained therefrom satisfy the requirements of the present invention. It had good operability, excellent flame retardancy, mechanical performance, heat stability (heat resistance), and excellent soft texture.
On the other hand, the heat-adhesive core-sheath type conjugate short fibers of Comparative Example 8 did not undergo the tension heat treatment, so that the dry heat shrinkage ratio was high, and the obtained nonwoven fabric had poor dimensional stability and poor texture. Was. The heat-adhesive core-sheath conjugate short fibers of Comparative Example 9 did not have sufficient flame retardancy due to the low content of the phosphorus compound. Since the heat-adhesive core-sheath type composite short fiber of Comparative Example 10 contained too much phosphorus compound, cut yarn was generated at the time of spinning, and roll wrap was generated at the time of stretching, and the operability was poor. The texture of the obtained nonwoven fabric was also bad. Since the heat-adhesive core-sheath type composite short fiber of Comparative Example 11 had a large sheath composite volume ratio and a small content of the phosphorus compound in the composite short fiber, the obtained nonwoven fabric had insufficient flame retardancy and texture. Was also inferior. Since both the Tm and the Tc of the low-melting polyester were high in the heat-adhesive core-sheath type conjugate short fiber of Comparative Example 12, the temperature of the processing machine could not be raised to a temperature at which the sheath melted during the heat bonding treatment, and a nonwoven fabric was obtained. I couldn't do that. The heat-adhesive core / sheath type composite short fiber of Comparative Example 13 had a low Tg in the sheath portion, so that the fibers adhered to each other at the time of spinning, the operability was poor, and the texture of the obtained nonwoven fabric was also poor. Further, since the low melting point polyester had a low Tm, the obtained nonwoven fabric was inferior in heat resistance. The heat-adhesive core-sheath type composite staple fiber of Comparative Example 14 has a high dry heat shrinkage because the sheath component is an amorphous low-melting polyester obtained by copolymerizing isophthalic acid, and the obtained nonwoven fabric is dimensionally stable. The heat resistance was poor, and the heat deformation was large and the heat resistance was poor.
[0068]
【The invention's effect】
The heat-adhesive core-sheath type composite staple fiber of the present invention has excellent flame retardancy, heat adhesion and heat resistance by regulating the composition of the polyester in the core and the sheath and the copolymerization amount of the phosphorus compound. And good operability can be obtained. The nonwoven fabric comprising the heat-adhesive core-sheath composite short fibers of the present invention is excellent in flame retardancy, mechanical properties, heat resistance, and soft texture, and is required in fields where flame retardancy and heat resistance are required ( Examples: furniture materials, building materials such as wall materials, automotive interior materials, etc.) can be widely used.

Claims (3)

A core-sheath composite in which a low-melting polyester having a glass transition point of 25 to 70 ° C, a crystallization onset temperature of 80 to 120 ° C, and a melting point of 140 to 190 ° C is disposed in a sheath, and a polyester in which a main repeating unit is alkylene terephthalate is disposed in a core. A thermoadhesive core-sheath composite short fiber, which satisfies the following (1) to (3) at the same time.
(1) The polyester at the core contains a phosphorus compound represented by the following formula (A), and the core fiber contains 3.0 to 10 mol%.
(2) The polyester at the core contains a phosphorus compound represented by the following formula (A), and contains 2.0 to 6.5 mol% in the composite fiber.
(3) The dry heat shrinkage at 110 ° C. is 5% or less.

(Wherein, R ¹ and R ³ represent a hydrocarbon group having 1 to 18 carbon atoms, R ² represents an ester-forming group, and A represents a trivalent organic residue. Note that this compound is an acid anhydride and It may be.) A low-melting polyester constituting the sheath of the composite fiber contains a terephthalic acid component, an ethylene glycol component, and at least one component of a 1,4-butanediol component, an adipic acid component, and an aliphatic lactone component. The heat-adhesive core-sheath composite short fiber according to claim 1, which is a polyester. A short-fiber nonwoven fabric comprising the heat-adhesive core-sheath composite short fiber according to claim 1 or 2, wherein the nonwoven fabric has an LOI value of 25 or more indicating flame retardancy.