JP3960100B2 - High strength polyolefin fiber and concrete molded body using the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、コンクリート補強効果に優れた高強度ポリオレフィン繊維及びこれを用いて成形したコンクリート成形体に関する。
【０００２】
【従来の技術】
コンクリート（セメントの硬化物）は、圧縮強度、耐久性、不燃性等の優れた性質に加えて安価であるため、建築、土木分野等に大量に使用されている。反面、コンクリートは、屈曲性が著しく低いことから、引張りや曲げ応力が加わることで、容易に亀裂や破損が生じる等、耐衝撃性が低いといった問題を有している。
【０００３】
近年、これらの問題点を改善するために、無機繊維、有機合成繊維等の種々の繊維を使用し、コンクリートを補強することが提案されている。このようなコンクリートの補強用繊維として、耐アルカリ性、耐熱性に優れ、オートクレーブ養生や蒸気養生ができることから、ポリオレフィン繊維が使用されている。しかし、ポリオレフィン繊維が疎水性で、セメントが親水性であるために、この繊維とセメントとを混合して製造したコンクリートの場合には、両者の接着性が悪いことから、ポリオレフィン繊維が、コンクリートマトリックスから素抜けてしまい、ポリオレフィン繊維の繊維強度等がコンクリート補強に十分に寄与されずに、コンクリートの補強が不十分であった。このように、従来のポリオレフィン繊維を補強用繊維として使用した場合には、ポリオレフィン繊維の長所と短所によって、補強性能を十分に発揮させることができず、コンクリートの補強が不十分となっていた。
【０００４】
このような問題を解決するために、近年、補強用繊維の断面を異形化する試みや、Ａ成分を芯成分とし、Ｂ成分をＡ成分と接合した状態で鞘成分とし、鞘成分に隆起した凸部と隆起していない凹部を有する複合繊維を用いて、コンクリート硬化後の繊維の引き抜きを制御して補強効果を向上させる試みがなされている（特開２０００−６４１１６）。しかし、補強用繊維に凹凸を付与することで、コンクリートとのアンカー効果は得られるものの、補強用繊維に凹凸を付与するために、構成樹脂や製糸条件が限定され、繊維本来の単糸強度が損なわれるという問題が新たに生じていた。このように、未だ満足できるコンクリート補強効果を有する補強用繊維は得られていない。
【０００５】
【発明が解決しようとする課題】
本発明の課題は、コンクリートマトリックスとの物理的結合力、すなわちコンクリート成形体中の繊維とコンクリートの引っかかりであるアンカー効果を飛躍的に向上させ、繊維の引き抜きを防止することが可能であり、かつ繊維の単糸強度も著しく高く、コンクリート補強用繊維に適した高強度ポリオレフィン繊維を提供することである。
【０００６】
【課題を解決するための手段】
本発明者らは、前記課題を解決するために、鋭意研究を重ねた。その結果、ポリプロピレン樹脂を主体とするポリオレフィン繊維の繊維表面を特定の構造とすることで、アンカー効果を飛躍的に向上できるという知見を見出し、この知見に基づいて本発明を完成するに至った。
本発明は、前記課題を解決するために以下の構成を有する。
【０００７】
（１）ポリプロピレン樹脂を主体とする、少なくとも９ｃＮ／ｄｔｅｘの単糸強度を有するポリオレフィン繊維であって、該ポリオレフィン繊維は、Ｑ値（分子量分布＝重量平均分子量／数平均分子量）が４以下であり、ＩＰＦ（アイソタクチックペンタッドフラクション）が、９３＜ＩＰＦ（ｍｏｌ％）＜１００であるポリプロピレン樹脂を用いて、２５０〜３５０℃の範囲の紡糸温度で紡糸し、繊維表面温度に対して繊維内部温度が低くなる状態で延伸することで生じる変形応力差によって繊維表面の曲面に沿って円周方向に形成された筋状の粗面構造を有していることを特徴とする高強度ポリオレフィン繊維。
（２）ポリプロピレン樹脂を主体とする、少なくとも９ｃＮ／ｄｔｅｘの単糸強度を有するポリオレフィン繊維であって、該ポリオレフィン繊維は、紡糸時の未延伸糸の引取り速度が、２００〜１５００ｍ／ｍｉｎであり、該未延伸糸を用いて、熱風温度が１２５〜１５５℃の熱風槽による非接触加熱下で、３０〜２００ｍ／ｍｉｎの延伸速度で延伸することで得られる高強度ポリオレフィン繊維。
（３）高強度ポリオレフィン繊維が、少なくとも１２ｃＮの対コンクリート引き抜き抵抗を有する前記（１）項または前記（２）項記載の高強度ポリオレフィン繊維。
（４）高強度ポリオレフィン繊維が、４以下のＱ値（分子量分布）であり、９３＜ＩＰＦ（ｍｏｌ％）＜１００であるポリプロピレン樹脂からなる延伸糸であって、該ポリオレフィン繊維は、少なくとも４．９ＧＰａ（約５００Ｋｇ／ｍｍ2）のヤング率を有する前記（１）〜（３）のいずれか１項記載の高強度ポリオレフィン繊維。
（５）前記（１）〜（４）のいずれか１項記載の高強度ポリオレフィン繊維を用いて成形したコンクリート成形体。
【０００８】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の高強度ポリオレフィン繊維は、ポリプロピレン樹脂を主体とする、少なくとも９ｃＮ／ｄｔｅｘの単糸強度を有し、繊維表面の曲面に沿って形成された筋状の粗面構造を有していることを特徴とするポリオレフィン繊維である。
【０００９】
本発明の高強度ポリオレフィン繊維は、繊維表面に筋状の粗面構造を有することから、コンクリート補強用繊維として使用した場合には、アンカー効果を発揮し、コンクリートマトリックスと補強繊維との間に強力な引き抜き抵抗が働くので、コンクリートマトリックスと補強用繊維との物理的結合力を飛躍的に向上できる。このとき、対コンクリート引き抜き抵抗は、少なくとも９ｃＮ／ｄｔｅｘであり、さらに少なくとも１２ｃＮであることが好ましい。なお、この筋状の粗面構造は、多数の凹凸を繊維軸方向に対して垂直方向に間隔を置いて存在している。この結果、コンクリートマトリックスから補強用繊維が素抜けることを抑制でき、さらに補強用繊維の有する強度が、コンクリート補強効果に十分に寄与できるようになる。従って、本発明の高強度ポリオレフィン繊維を補強用繊維として使用したコンクリート成形体は、該補強用繊維により曲げ強度や衝撃強さを著しく向上できる。
【００１０】
図１は、本発明の高強度ポリオレフィン繊維の表面（側面）を電子顕微鏡で観察したときの電子顕微鏡写真である。図１に見られるように、繊維表面の曲面に沿って形成された無数の凹凸からなる筋状の粗面構造を形成している。また繊維の断面形状は、部分的に円形または異形の断面形状とすることができる。異形断面の形状としては、偏平形、三角〜八角形の角型、Ｔ字形、多葉形、中空断面形等の任意の形状とすることができる。繊維の形状としては、繊維軸方向に直線的な形状、捲縮の付与により湾曲した形状、直線部と曲線部の両方を併せ持つ形状とすることができる。本発明の高強度ポリオレフィン繊維は、繊維表面の曲面に沿って形成された筋状の粗面構造を有していれば繊維形状は特に限定されない。
【００１１】
本発明の高強度ポリオレフィン繊維は、ポリプロピレン樹脂を主体として構成されている。なお、ポリプロピレン樹脂を主体とするとは、少なくとも８０重量％のポリプロピレン樹脂を含有することをいう。具体的には、１種類のポリプロピレン樹脂のみを原料樹脂とする単一繊維、少なくとも２種類の異なるポリプロピレン樹脂の組成物を原料樹脂とする単一繊維、少なくとも２種類の異なるポリプロピレン樹脂を鞘芯型、並列型、偏心鞘芯型等の複合形態に配した複合繊維を挙げることができる。
【００１２】
本発明の高強度ポリオレフィン繊維の原料樹脂には、本発明の効果を妨げない範囲内でさらに酸化防止剤、光安定剤、紫外線吸収剤、中和剤、造核剤、エポキシ安定剤、滑剤、抗菌剤、難燃剤、帯電防止剤、顔料、可塑剤等の添加剤を必要に応じて適宜添加してもよい。
【００１３】
本発明の原料樹脂としては、Ｑ値（分子量分布＝重量平均分子量／数平均分子量）が４以下であり、ＩＰＦ（アイソタクチックペンタッドフラクション）が、９３＜ＩＰＦ（ｍｏｌ％）＜１００であるポリプロピレン樹脂を用いることが望ましい。ポリプロピレン樹脂のＱ値が４以下であると、延伸性を著しく阻害する高分子量成分が少なく、高い延伸性が得られるので好ましい。また、ＩＰＦは立体規則性の高さの指標であり、ＩＰＦが高いほど結晶性が高く、高強度のポリプロピレン繊維が得られるので、ポリプロピレン樹脂のＩＰＦは、９３＜ＩＰＦ（ｍｏｌ％）＜１００の範囲が好ましい。
【００１４】
本発明の高強度ポリオレフィン繊維は、以下の製造方法により製造できる。
紡糸条件、延伸条件を以下のようにすることで、ポリオレフィン繊維に９ｃＮ／ｄｔｅｘ以上の高い単糸強度を付与することができる。
本発明の高強度ポリオレフィン繊維は、前記ポリプロピレン樹脂を原料樹脂として用い、２５０〜３５０℃の範囲の紡糸温度で紡糸することが好ましい。この範囲において、できるだけ高温で溶融紡糸することで、得られる未延伸糸は、分子配向が抑えられ、次工程の延伸工程において、高倍率で延伸できるため、高い単糸強度のオレフィン繊維が得られやすくなり好ましい。紡糸温度が２５０℃より著しく低温であると紡糸口金から押出された繊維状のポリプロピレン溶融物は、固化温度まで急速に冷却され、固化点での繊維の変形が大きく、より分子配向が進んだ未延伸糸となりやすい。また紡糸温度が３５０℃より著しく高温であると、ポリプロピレン樹脂の熱分解が急激に進み、ポリプロピレンの分子鎖が著しく切断されて低分子量化し、高倍率で延伸しても、ポリオレフィン繊維に高い単糸強度が得られない場合がある。
【００１５】
また、紡糸口金から押出されたポリプロピレン溶融物を冷却する場合、従来の方法、例えば冷風、水、グリセリン等でポリプロピレン樹脂の融点以下の温度まで冷却し、引き取ることができるが、未延伸糸の分子配向を極力抑えるためには、急冷するのではなく、送風等の方法で空気により徐冷却することが望ましい。このとき、より分子配向を抑えた未延伸糸を得るために、風量は弱く、温度は低温になり過ぎないように、空気の温度、風量を設定し、冷却速度を調節することが好ましい。紡糸口金から押出されたポリプロピレン溶融物の温度が２５０〜３５０℃の範囲であり、かつ適度な冷却速度である場合に、得られた未延伸糸の高次構造を延伸性に優れる擬似六方晶にすることが可能となる。
【００１６】
紡糸時の未延伸糸の引取り速度は、分子配向の進んでいない未延伸糸とするためになるべく低速であることが望ましい。引取り速度が低速であると、繊維状のポリプロピレン溶融物の固化点での変形が小さくなり、逆に引取り速度が高速であると繊維状のポリプロピレン溶融物の固化点での変形が大きくなる。即ち分子配向の進んだ未延伸糸構造となるために延伸性が低下し、結果として高強力なポリプロピレン繊維が得られない。また引取り速度がポリプロピレン溶融物の自由落下速度よりも低速過ぎると均一な未延伸糸を得られなくなり、繊度のばらつきを起こす。従って引取り速度は２００〜１５００ｍ／ｍｉｎ、更には３００〜１０００ｍ／ｍｉｎであることが好ましい。
【００１７】
次に、延伸工程について説明する。
本発明の高強度ポリオレフィン繊維は、延伸条件を以下のようにすることで、繊維表面の曲面に沿って形成された筋状の粗面構造を有することができる。なお、繊維表面を粗面構造とする方法としては、例えばエンボス加工法等の方法が知られているが、繊維の単糸強度が著しく低下する等の問題がある。しかし、以下の方法で延伸を実施することにより、繊維表面の曲面に沿って形成された筋状の粗面構造を有し、かつ高い単糸強度を持つ延伸糸を得ることができる。
【００１８】
ポリオレフィン繊維に、９ｃＮ／ｄｔｅｘ以上の単糸強度を付与し、同時に前記繊維表面の曲面に沿って、筋状の粗面構造を形成する方法としては、前述の方法で得た未延伸糸を用いて、熱風槽による非接触加熱下で延伸することで得られる。非接触加熱下で延伸することで、金属加熱ロール延伸等の接触加熱下で延伸するよりも高倍率で延伸することが可能である。延伸倍率は、繊維の破断が起きない範囲で、可能な限り高い延伸倍率で行うことが好ましい。この結果として強度が極めて高いポリオレフィン繊維が得られる。なお、熱風を加熱媒体として用いると、熱風と被延伸物（延伸中の未延伸糸）との熱交換速度と、被延伸物の通過速度との兼ね合いにより、繊維内部と表面との間に温度勾配（熱勾配）が生じる。つまり繊維表面温度に対して繊維内部温度は低くなる。この状態で、未延伸糸を高倍率で延伸すると、繊維内部（中心部）と表面との間に変形応力差が生じ、変形応力の大きい、即ち変形しにくい繊維内部は、変形速度に対して分子コンホメーションの変化による分子再配列が追随できない現象が生じる。その結果、繊維内部には、微細なボイド、空孔が生じ、変形応力の小さい繊維表面には、そのボイドの生成に誘発されて凹凸状の筋状の粗面構造を形成するのである。
【００１９】
被延伸物の熱風槽通過速度が、このような繊維内部と繊維表面との間に温度勾配が生じない程に十分に遅い場合には、繊維表面に粗面構造を形成しない。逆に被延伸物の熱風槽通過速度が、被延伸物を高倍率延伸するに足るまで十分に加熱されない程に速過ぎる場合には、結果として高強度のポリオレフィン繊維は得られない。従って延伸速度は、３０〜２００ｍ／ｍｉｎが好ましく、更には５０〜１００ｍ／ｍｉｎであることが望ましい。
【００２０】
熱風槽の熱風温度は十分な延伸性を確保するために、ポリプロピレン樹脂の結晶分散温度以上であり、かつ融点以下であることが望ましい。つまり、熱風温度は、１２５〜１５５℃、更には１３５〜１５０℃であることが望ましい。
【００２１】
延伸操作は１段延伸、２段以上の多段延伸の何れであってもよい。２段以上の多段延伸を行う場合には、少なくとも最終延伸段階で熱風延伸槽による延伸を行うことで、繊維表面の曲面に沿って形成された筋状の粗面構造を有する高強度ポリオレフィン繊維を得ることができ、その前段階の延伸では金属加熱ロール延伸、温水延伸等のいずれの延伸方法を採用してもよい。
【００２２】
このようなポリプロピレン樹脂を用いて、紡糸、延伸工程を経ることで、繊維表面の曲面に沿って筋状の粗面構造（凹凸の構造）が形成される。この結果、単糸強度が少なくとも９ｃＮ／ｄｔｅｘである高強度ポリオレフィン繊維が得られるのである。この高強度ポリオレフィン繊維は、少なくとも１２ｃＮの対コンクリート引き抜き抵抗を有することが好ましい。また、高強度ポリオレフィン繊維は、少なくとも４．９ＧＰａ（約５００ｋｇｆ／ｍｍ2）のヤング率を有することが好ましい。なお、ヤング率は、繊維補強コンクリート成形体の耐衝撃性を向上できることから、より好ましくは６ＧＰａ以上であり、更に好ましくは、９ＧＰａ以上である。
【００２３】
なお、本発明の高強度ポリオレフィン繊維をコンクリート補強用繊維として用いるときには、セメントスラリー中での分散性、セメントとの親和性を向上させるために、繊維表面を界面活性剤等で処理しておくことが望ましい。界面活性剤としては、高級脂肪酸金属塩、高級アルコール硫酸エステル金属塩、高級アルキルエーテル硫酸エステル金属塩、アルキルベンゼンスルホン酸金属塩、アルキルベンゼンナフタレンスルホン酸金属塩、パラフィンスルホン酸金属塩等の親水性油剤を使用することができる。高級脂肪酸金属塩としては、オレフィン酸カリウム塩、オクチル酸カリウム塩、ステアリン酸カリウム塩、ベヘニン酸カリウム塩、リノール酸カリウム塩が例示できる。
【００２４】
繊維表面への界面活性剤の付着は、紡糸工程、延伸工程、繊維加工後のいずれの段階で付着させてもよい。また付着方法は、ローラー法、浸漬法、噴霧法、パットドライ法等を用いることができる。
【００２５】
このようなコンクリート補強用繊維を混入させたコンクリート成形体は、高強度ポリオレフィン繊維の強度を損なうことなく、高強度ポリオレフィン繊維とコンクリート間の物理的結合力を向上させることができるので、高強度ポリオレフィン繊維のポテンシャルを十分にコンクリート成形体補強に発揮させることができる。このとき、前記繊維で補強されたコンクリート成形体は、少なくとも２６．５ＭＰａ（約２７０ｋｇｆ／ｃｍ2）の曲げ強度と、少なくとも１７．６４ｋＪ／ｍ2（１８ｋｇｆ・ｃｍ／ｃｍ2）の衝撃強さを有し、より好ましくは、少なくとも２８ＭＰａの曲げ強度と、少なくとも１９ｋＪ／ｍ2の衝撃強さを有していることである。
【００２６】
コンクリート成形体中へのコンクリート補強用繊維の配合割合は、目的とするコンクリート成形体の性能、機能、用途にあわせて任意に選択できるが、一般にはセメントを含む水硬性組成物に対して、０．０５〜２０重量％の配合割合であることが望ましく、更には０．１〜１０重量％であることが望ましい。また補強用繊維として他の繊維を併用しても何ら差し支えない。併用できる繊維としてはパルプ等の天然繊維、ＰＶＡ系繊維、アクリル繊維、ポリアリレート繊維等の合成繊維が挙げられる。更に、細骨材、粗骨材を併用することが可能であり、その一例としては、砂、砂利、砕石等が挙げられる。
【００２７】
【実施例】
以下、実施例にて本発明を更に具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
【００２８】
各種物性は以下の方法に従って測定した。
Ｑ値（分子量分布）：ゲルパーミエーションクロマトグラフィー（ＧＰＣ）法により、カラムとして、東ソー（株）製「ＰＳＫｇｅｌ ＧＭＨ６−ＨＴ」（商品名）を使用し、測定装置として、ウォーターズ社製「ＧＰＣ−１５０Ｃ型」（商品名）を用いて、試験体（ポリプロピレン樹脂）を、ｏ−ジクロロベンゼンに、その濃度が０．０５重量％となるように溶解し、得られた溶液を温度１３５℃で測定して求めた。
ＩＰＦ（アイソタクチックペンタッドフラクション）：日本電子社製「ＪＮＭ ＧＸ−２７０型」（商品名）を用いて、Ｍａｃｒｏｍｏｌｅｃｕｌｅｓ，６、９２５（１９７３）に記載の、13Ｃ−ＮＭＲスペクトル法により求めた。13Ｃ−ＮＭＲスペクトルにおいて５個連続したプロピレン単量体単位を示すピークからアイソタクチック結合に相当するピーク分率を求めた。ピークの帰属はＭａｃｒｏｍｏｌｅｃｕｌｅｓ，８、６８７（１９７５）に記載の方法で行なった。
実効延伸倍率：未延伸糸繊度／延伸糸繊度の式より算出した。
単糸強度：ＪＩＳ Ｌ １０１５に準じて行なった。
ヤング率：単糸強度測定時の結果を解析して算出した。
対コンクリート引き抜き抵抗：水と普通ポルトランドセメントを水／セメント＝１／３の重量割合で混合して得られた成形体に、補強用繊維を１ｃｍ埋め込む。これを２５℃の水中で２８日間水中養生して、コンクリート成形体を得た。次いでコンクリートから補強用繊維を２０ｍｍ／ｍｉｎの速度で引き抜き、その際の最大引き抜き荷重を対コンクリート引き抜き抵抗とした。
繊維補強コンクリート成形体：水と普通ポルトランドセメントと補強用繊維を、水／セメント／繊維＝１／３／０．０３の重量割合で混合し、１１７６Ｎ（１２０ｋｇｆ）の圧力によって１０秒間圧縮し、１サンプル３０ｃｍ×２５ｃｍ×１．１ｃｍのサイズで成形体とした。これを６０℃の蒸気中で５時間養生させた後、２８日間室内に放置してコンクリート成形体を得た。
曲げ試験：ＪＩＳ Ａ １４０８（１９９５−１−１）に準じて行なった。
衝撃試験：ＪＩＳ Ｂ ７７２２（１９９５−１−１）に準じて行なった。
【００２９】
実施例１
ポリプロピレン樹脂として、Ｑ値が３．２、ＩＰＦが９６ｍｏｌ％のチッソ（株）製アイソタクチックポリプロピレン（商品名「チッソポリプロ ＣＳ３５４０」、融点１６５℃）を使用し、これを３２０℃の紡糸温度で溶融紡糸して未延伸糸を得た。得られた未延伸糸を使用し、加熱ヒーターと循環ファンからなる熱風槽中で、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。このときの延伸ラインスピードは５０ｍ／ｍｉｎ、熱風槽温度は１４３℃とした。得られた延伸糸を５ｍｍに切断して、高強度ポリオレフィン繊維とした。使用したポリプロピレン樹脂と、得られた高強度ポリオレフィン繊維の特性を表１に示す。この高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３０】
実施例２
実施例１で得られた未延伸糸を使用し、２段階延伸を行った。延伸の第１段目は９０℃の加熱ロールで、破断延伸倍率の６０％の倍率で延伸し、延伸の第２段目は熱風温度1３８℃の熱風槽中で、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた高強度ポリオレフィン繊維の特性を表１に示す。この高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３１】
実施例３
実施例１で得られた未延伸糸を使用し、２段階延伸を行った。延伸の第１段目は熱風温度1４３℃の熱風槽中で、破断延伸倍率の６０％の倍率で延伸し、延伸の第２段目は熱風温度１４３℃の熱風槽中で、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた高強度ポリオレフィン繊維の特性を表１に示す。この高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３２】
実施例４
ポリプロピレン樹脂として、Ｑ値が３．８、ＩＰＦが９４ｍｏｌ％のチッソ（株）製アイソタクチックポリプロピレン（商品名「チッソポリプロ ＲＳ２５１４」、融点１６５℃）を使用し、これを３２０℃の紡糸温度で溶融紡糸して未延伸糸を得た。得られた未延伸糸を使用し、実施例１で用いた、熱風温度１４３℃の熱風槽中で、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた高強度ポリオレフィン繊維の特性を表１に示す。この高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３３】
実施例５
実施例４で得られた未延伸糸を使用し、２段階延伸を行った。延伸の第１段目は９０℃の温水槽で、破断延伸倍率の６０％の倍率で延伸し、延伸の第２段目は熱風温度1３８℃の熱風槽中で破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた高強度ポリオレフィン繊繊維の特性を表１に示す。この高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。成形体の特性を表１に示す。
【００３４】
比較例１
ポリプロピレン樹脂として、Ｑ値が７．２、ＩＰＦが９０ｍｏｌ％のチッソ（株）製アイソタクチックポリプロピレン（商品名「チッソポリプロ ＲＳ２２３６」、融点１６２℃）を使用し、これを３２０℃の紡糸温度で溶融紡糸して未延伸糸を得た。得られた未延伸糸を使用し、９０℃の加熱ロールで、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた延伸糸を５ｍｍに切断して、高強度ポリオレフィン繊維とした。使用したポリプロピレン樹脂と、この高強度ポリオレフィン繊維の特性を表１に示す。また得られた高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３５】
比較例２
比較例１で得られた未延伸糸を使用し、９０℃の温水槽中で、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた高強度ポリオレフィン繊維の特性を表１に示す。この高強度ポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３６】
比較例３
実施例１で得られた未延伸糸を使用し、２段階延伸を行った。延伸の第１段目は１２０℃の熱ロールで、破断延伸倍率の６０％の倍率で延伸し、延伸の第２段目は１２０℃の熱ロールで、破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。このポリオレフィン繊維の特性を表１に示す。また得られたポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３７】
比較例４
実施例１で得られた未延伸糸を使用し、２段階延伸を行った。延伸の第１段目は９０℃の温水槽中で、破断延伸倍率の６０％の倍率で延伸し、延伸の第２段目は１３０℃の熱ロールで破断延伸倍率の９０％の倍率で延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られたポリオレフィン繊維の特性を表１に示す。このポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３８】
比較例５
特開２０００−６４１１６の実施例の条件に準拠して、ポリプロピレン樹脂として、Ｑ値が３．２、ＩＰＦが９６ｍｏｌ％のチッソ（株）製アイソタクチックポリプロピレン（商品名「チッソポリプロ ＣＳ３５４０」、融点１６５℃）を使用し、これを芯成分に配し、東ソー（株）製低密度ポリエチレン（商品名「ペトロセン ＰＥ３５０」、融点１０７℃）を鞘成分に配して溶融紡糸して得られた未延伸糸を６０℃の熱ロールで１段延伸し、繊維仕上剤として高級脂肪酸金属塩であるオレイン酸カリウム塩をローラー法で１．０重量％付着させて、延伸糸を得た。得られた繊維の繊維表面は鞘成分が隆起した凸部と隆起していない凹部からなる凹凸を有していた。使用したポリプロピレン樹脂と、得られたポリオレフィン繊維の特性を表１に示す。このポリオレフィン繊維をコンクリート補強用繊維として使用して、前述のコンクリート成形体製造方法に従って製造し、コンクリート成形体を得た。この成形体の特性を表１に示す。
【００３９】
【表１】
実施例１〜５に示すように非接触過熱下の熱風槽中で延伸することにより、９ｃＮ／ｄｔｅｘ以上の単糸強度と、筋状の粗面構造の両特性を兼ね備えた繊維を得ることができた。図１は実施例により得られた、本発明に係わる高強度ポリオレフィン繊維の表面（側面）を観察した拡大写真である。繊維表面には、曲面に沿って円周方向に形成された筋状の粗面構造が観察できる。このように繊維表面が粗面構造であることにより、コンクリートマトリックスに対するアンカー効果が向上し、１２ｃＮ以上の対コンクリート引き抜き抵抗を有する。またこのポリオレフィン繊維をコンクリート補強用繊維として用いた場合、コンクリート成形体は、２６．５ＭＰａ（２７０ｋｇｆ／ｃｍ2）以上の曲げ強度と、１７．６４ｋＪ／ｍ2（１８ｋｇｆ・ｃｍ／ｃｍ2）以上の衝撃強さを示し、高いコンクリート補強効果を発揮し、得られたコンクリート成形体は、力学物性に優れていることがわかった。
【００４１】
これに対し、比較例１〜４に示す、製造方法で得られたポリオレフィン繊維は、単糸強度が低く、また繊維表面の構造は平滑であった。このポリオレフィン繊維をコンクリート補強用繊維として用いたところ、コンクリートマトリックスから繊維の素抜けが生じる等、十分な補強効果を発揮できなかった。また比較例５に示した繊維は、繊維表面が凸凹の粗面構造を形成していたが、単糸強度は著しく低かった。このポリオレフィン繊維をコンクリート補強用繊維として用いたところ、単糸強度が低いために繊維に破断が生じ、コンクリート成形体の力学物性は、曲げ強度、衝撃強さともに低く、十分なコンクリート補強効果が得られなかった。
【００４２】
【発明の効果】
本発明の高強度ポリオレフィン繊維は、繊維表面の曲面に沿って形成された筋状の粗面構造を有し、かつ高い強度を有するので、コンクリートマトリックスとの物理的結合力が大きく、コンクリート補強効果に極めて優れている。また本発明のコンクリート成形体は、単糸強度が高く、かつコンクリートマトリックスとの物理的結合力が大きい高強度ポリオレフィン繊維が充填されているために、曲げ強度および衝撃強度に優れている。
【図面の簡単な説明】
【図１】 高強度ポリオレフィン繊維の表面（側面）を電子顕微鏡で観察したときの電子顕微鏡写真（×２０００倍）である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength polyolefin fiber excellent in a concrete reinforcing effect and a concrete molded body formed using the same.
[0002]
[Prior art]
Since concrete (hardened cement) is inexpensive in addition to excellent properties such as compressive strength, durability, and noncombustibility, it is used in large quantities in the construction and civil engineering fields. On the other hand, concrete has a problem that its impact resistance is low, such as cracking and breakage easily by applying tensile or bending stress because of its extremely low flexibility.
[0003]
In recent years, in order to improve these problems, it has been proposed to reinforce concrete using various fibers such as inorganic fibers and organic synthetic fibers. As such concrete reinforcing fibers, polyolefin fibers are used because they are excellent in alkali resistance and heat resistance and can be cured by an autoclave or steam. However, since the polyolefin fiber is hydrophobic and the cement is hydrophilic, in the case of concrete produced by mixing this fiber and cement, the adhesion between the two is poor. As a result, the fiber strength of the polyolefin fiber did not sufficiently contribute to the concrete reinforcement, and the reinforcement of the concrete was insufficient. Thus, when the conventional polyolefin fiber is used as the reinforcing fiber, the reinforcing performance cannot be sufficiently exhibited due to the advantages and disadvantages of the polyolefin fiber, and the reinforcement of the concrete is insufficient.
[0004]
In order to solve such problems, in recent years, attempts have been made to deform the cross section of the reinforcing fiber, and the A component is used as the core component, and the B component is joined to the A component as the sheath component, and the sheath component has been raised. Attempts have been made to improve the reinforcing effect by controlling the drawing of the fiber after hardening the concrete using a composite fiber having a convex part and a concave part that is not raised (Japanese Patent Laid-Open No. 2000-64116). However, by providing irregularities to the reinforcing fibers, the anchor effect with concrete can be obtained, but in order to impart irregularities to the reinforcing fibers, the constituent resin and yarn making conditions are limited, and the original single yarn strength is There was a new problem of damage. Thus, a reinforcing fiber having a satisfactory concrete reinforcing effect has not yet been obtained.
[0005]
[Problems to be solved by the invention]
The problem of the present invention is that it is possible to drastically improve the physical bonding force with the concrete matrix, that is, the anchor effect that is the catch of the fiber and concrete in the concrete molded body, and to prevent the fiber from being pulled out, and An object of the present invention is to provide a high-strength polyolefin fiber suitable for a concrete reinforcing fiber since the single yarn strength of the fiber is remarkably high.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have conducted intensive research. As a result, the inventors have found that the anchor effect can be remarkably improved by making the fiber surface of the polyolefin fiber mainly composed of polypropylene resin have a specific structure, and the present invention has been completed based on this finding.
The present invention has the following configuration in order to solve the above problems.
[0007]
(1) A polyolefin fiber mainly composed of polypropylene resin and having a single yarn strength of at least 9 cN / dtex,Using a polypropylene resin having a Q value (molecular weight distribution = weight average molecular weight / number average molecular weight) of 4 or less and an IPF (isotactic pentad fraction) of 93 <IPF (mol%) <100, 250 to Due to the difference in deformation stress caused by spinning at a spinning temperature in the range of 350 ° C. and drawing in a state where the fiber internal temperature is lower than the fiber surface temperature.Along the curved surface of the fiber surfaceIn the circumferential directionA high-strength polyolefin fiber having a formed streaky rough surface structure.
(2) A polyolefin fiber mainly composed of polypropylene resin and having a single yarn strength of at least 9 cN / dtex, and the polyolefin fiber has an undrawn yarn take-up speed of 200 to 1500 m / min during spinning. A high-strength polyolefin fiber obtained by stretching the unstretched yarn at a stretching speed of 30 to 200 m / min under non-contact heating in a hot air bath having a hot air temperature of 125 to 155 ° C.
(3The item (1), wherein the high-strength polyolefin fiber has a resistance to pulling out of concrete of at least 12 cN.Or the item (2)High-strength polyolefin fiber as described.
(4) A high-strength polyolefin fiber having a Q value (molecular weight distribution) of 4 or less and a drawn yarn made of a polypropylene resin with 93 <IPF (mol%) <100, and the polyolefin fiber is at least 4.9 GPa ( About 500Kg / mm2(1) having a Young's modulus ofAny one of-(3)High-strength polyolefin fiber as described.
(5) (1) to (4The concrete molded object shape | molded using the high strength polyolefin fiber of any one of (1).
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The high-strength polyolefin fiber of the present invention has a single-strand strength of at least 9 cN / dtex, mainly composed of polypropylene resin, and has a streaky rough surface structure formed along the curved surface of the fiber surface. Is a polyolefin fiber characterized by
[0009]
Since the high-strength polyolefin fiber of the present invention has a streaky rough surface structure on the fiber surface, when used as a concrete reinforcing fiber, it exhibits an anchoring effect and is strong between the concrete matrix and the reinforcing fiber. Since the pull-out resistance works, the physical bonding force between the concrete matrix and the reinforcing fiber can be dramatically improved. At this time, the resistance to pulling out from concrete is at least 9 cN / dtex, and preferably at least 12 cN. In addition, this stripe-like rough surface structure has many unevenness at intervals in the direction perpendicular to the fiber axis direction. As a result, it is possible to prevent the reinforcing fibers from being removed from the concrete matrix, and the strength of the reinforcing fibers can sufficiently contribute to the concrete reinforcing effect. Therefore, the concrete molded body using the high-strength polyolefin fiber of the present invention as the reinforcing fiber can remarkably improve the bending strength and impact strength by the reinforcing fiber.
[0010]
FIG. 1 is an electron micrograph when the surface (side surface) of the high-strength polyolefin fiber of the present invention is observed with an electron microscope. As can be seen in FIG. 1, a streaky rough surface structure composed of innumerable irregularities formed along the curved surface of the fiber surface is formed. The cross-sectional shape of the fiber can be a partially circular or irregular cross-sectional shape. The shape of the irregular cross section may be any shape such as a flat shape, a triangular to octagonal square shape, a T-shape, a multi-leaf shape, and a hollow cross-sectional shape. The shape of the fiber can be a linear shape in the fiber axis direction, a shape curved by applying crimp, or a shape having both a straight portion and a curved portion. The fiber shape of the high-strength polyolefin fiber of the present invention is not particularly limited as long as it has a streaky rough surface structure formed along the curved surface of the fiber surface.
[0011]
The high-strength polyolefin fiber of the present invention is mainly composed of a polypropylene resin. In addition, having a polypropylene resin as a main component means containing at least 80% by weight of a polypropylene resin. Specifically, a single fiber using only one type of polypropylene resin as a raw material resin, a single fiber using a composition of at least two different types of polypropylene resins as a raw material resin, and at least two different types of polypropylene resins as a sheath core type And composite fibers arranged in a composite form such as a parallel type and an eccentric sheath core type.
[0012]
In the raw material resin of the high-strength polyolefin fiber of the present invention, an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizer, a nucleating agent, an epoxy stabilizer, a lubricant, and the like within a range not impeding the effects of the present invention Additives such as antibacterial agents, flame retardants, antistatic agents, pigments, plasticizers and the like may be added as necessary.
[0013]
The raw material resin of the present invention has a Q value (molecular weight distribution = weight average molecular weight / number average molecular weight) of 4 or less, and IPF (isotactic pentad fraction) is 93 <IPF (mol%) <100. It is desirable to use a polypropylene resin. It is preferable for the Q value of the polypropylene resin to be 4 or less because there are few high molecular weight components that significantly impair the stretchability, and high stretchability can be obtained. In addition, IPF is an index of high stereoregularity, and the higher the IPF, the higher the crystallinity and the higher the strength of the polypropylene fiber. Therefore, the IPF of the polypropylene resin is 93 <IPF (mol%) <100. A range is preferred.
[0014]
The high-strength polyolefin fiber of the present invention can be produced by the following production method.
By setting the spinning conditions and drawing conditions as follows, it is possible to impart a high single yarn strength of 9 cN / dtex or more to the polyolefin fiber.
The high-strength polyolefin fiber of the present invention is preferably spun at a spinning temperature in the range of 250 to 350 ° C. using the polypropylene resin as a raw material resin. In this range, by performing melt spinning at as high a temperature as possible, the resulting undrawn yarn is suppressed in molecular orientation and can be drawn at a high magnification in the drawing step of the next step, resulting in a high single yarn strength olefin fiber. It becomes easy and preferable. When the spinning temperature is significantly lower than 250 ° C., the fibrous polypropylene melt extruded from the spinneret is rapidly cooled to the solidification temperature, the deformation of the fiber at the solidification point is large, and the molecular orientation is more advanced. It tends to be drawn yarn. If the spinning temperature is significantly higher than 350 ° C., the thermal decomposition of the polypropylene resin proceeds rapidly, the molecular chain of the polypropylene is severely cut to lower the molecular weight, and even if the fiber is stretched at a high magnification, the polyolefin fiber has a high single yarn. Strength may not be obtained.
[0015]
Further, when cooling the polypropylene melt extruded from the spinneret, it can be cooled to a temperature below the melting point of the polypropylene resin with a conventional method, for example, cold air, water, glycerin, etc. In order to suppress the orientation as much as possible, it is desirable to gradually cool with air by a method such as blowing instead of rapidly cooling. At this time, in order to obtain an undrawn yarn in which molecular orientation is further suppressed, it is preferable to set the air temperature and air volume and adjust the cooling rate so that the air volume is weak and the temperature does not become too low. When the temperature of the polypropylene melt extruded from the spinneret is in the range of 250 to 350 ° C. and an appropriate cooling rate, the higher-order structure of the obtained undrawn yarn is converted into a pseudo hexagonal crystal having excellent drawability. It becomes possible to do.
[0016]
It is desirable that the undrawn yarn take-up speed during spinning is as low as possible in order to obtain an undrawn yarn having no advanced molecular orientation. When the take-up speed is low, the deformation at the solidification point of the fibrous polypropylene melt decreases, and conversely, when the take-up speed is high, the deformation at the solidification point of the fibrous polypropylene melt increases. . That is, the unstretched yarn structure with advanced molecular orientation results in a decrease in stretchability, and as a result, a high-strength polypropylene fiber cannot be obtained. On the other hand, if the take-up speed is too lower than the free fall speed of the polypropylene melt, a uniform undrawn yarn cannot be obtained, resulting in variations in fineness. Accordingly, the take-up speed is preferably 200 to 1500 m / min, more preferably 300 to 1000 m / min.
[0017]
Next, the stretching process will be described.
The high-strength polyolefin fiber of the present invention can have a streaky rough surface structure formed along the curved surface of the fiber surface by setting the drawing conditions as follows. In addition, as a method of making the fiber surface into a rough surface structure, for example, a method such as an embossing method is known, but there is a problem that the single yarn strength of the fiber is remarkably lowered. However, by carrying out drawing by the following method, a drawn yarn having a streaky rough surface structure formed along the curved surface of the fiber surface and having high single yarn strength can be obtained.
[0018]
As a method for imparting a single yarn strength of 9 cN / dtex or more to a polyolefin fiber and simultaneously forming a streaky rough surface structure along the curved surface of the fiber surface, the undrawn yarn obtained by the above method is used. And it is obtained by stretching under non-contact heating in a hot air tank. By stretching under non-contact heating, it is possible to stretch at a higher magnification than when stretching under contact heating such as metal heating roll stretching. The draw ratio is preferably as high as possible within the range where fiber breakage does not occur. As a result, an extremely high strength polyolefin fiber is obtained. When hot air is used as a heating medium, the temperature between the inside of the fiber and the surface depends on the balance between the heat exchange rate between the hot air and the object to be drawn (undrawn yarn being drawn) and the passing speed of the object to be drawn. A gradient (thermal gradient) occurs. That is, the fiber internal temperature is lower than the fiber surface temperature. When the undrawn yarn is drawn at a high magnification in this state, a deformation stress difference is generated between the inside of the fiber (center portion) and the surface, and the inside of the fiber having a large deformation stress, that is, a hard to deform, A phenomenon occurs in which molecular rearrangement cannot follow following changes in molecular conformation. As a result, fine voids and pores are generated inside the fiber, and the surface of the fiber having a small deformation stress is induced by the formation of the void to form an uneven streaky rough surface structure.
[0019]
When the speed of the stretched object passing through the hot air tank is sufficiently slow so that no temperature gradient is generated between the inside of the fiber and the fiber surface, a rough surface structure is not formed on the fiber surface. On the other hand, when the hot-air tank passing speed of the stretched product is too high so that the stretched product is not heated enough to be stretched at a high magnification, a high-strength polyolefin fiber cannot be obtained as a result. Accordingly, the stretching speed is preferably 30 to 200 m / min, and more preferably 50 to 100 m / min.
[0020]
In order to ensure sufficient stretchability, it is desirable that the hot air temperature of the hot air tank is not less than the crystal dispersion temperature of the polypropylene resin and not more than the melting point. That is, the hot air temperature is preferably 125 to 155 ° C, and more preferably 135 to 150 ° C.
[0021]
The stretching operation may be either one-stage stretching or multi-stage stretching of two or more stages. When performing multi-stage stretching of two or more stages, a high-strength polyolefin fiber having a streaky rough surface structure formed along the curved surface of the fiber surface is obtained by performing stretching in a hot-air stretching tank at least in the final stretching stage. Any of the stretching methods such as metal heating roll stretching and warm water stretching may be employed in the preceding stretching.
[0022]
By using such a polypropylene resin, through a spinning and stretching process, a streaky rough surface structure (uneven structure) is formed along the curved surface of the fiber surface. As a result, a high-strength polyolefin fiber having a single yarn strength of at least 9 cN / dtex is obtained. This high strength polyolefin fiber preferably has a resistance to pulling out of concrete of at least 12 cN. The high-strength polyolefin fiber is at least 4.9 GPa (about 500 kgf / mm2It is preferable to have a Young's modulus of In addition, since Young's modulus can improve the impact resistance of a fiber reinforced concrete molded object, More preferably, it is 6 GPa or more, More preferably, it is 9 GPa or more.
[0023]
When the high-strength polyolefin fiber of the present invention is used as a concrete reinforcing fiber, the fiber surface should be treated with a surfactant or the like in order to improve the dispersibility in the cement slurry and the affinity with the cement. Is desirable. Surfactants include hydrophilic oils such as higher fatty acid metal salts, higher alcohol sulfate metal salts, higher alkyl ether sulfate metal salts, alkylbenzene sulfonic acid metal salts, alkylbenzene naphthalene sulfonic acid metal salts, and paraffin sulfonic acid metal salts. Can be used. Examples of the higher fatty acid metal salt include olefinic acid potassium salt, octylic acid potassium salt, stearic acid potassium salt, behenic acid potassium salt, and linoleic acid potassium salt.
[0024]
The surfactant may be attached to the fiber surface at any stage after the spinning process, the drawing process, and the fiber processing. Further, as an adhesion method, a roller method, a dipping method, a spraying method, a pad drying method, or the like can be used.
[0025]
A concrete molded body in which such a fiber for reinforcing concrete is mixed can improve the physical bonding force between the high-strength polyolefin fiber and the concrete without impairing the strength of the high-strength polyolefin fiber. The fiber potential can be sufficiently exerted to reinforce the concrete compact. At this time, the concrete molded body reinforced with the fibers is at least 26.5 MPa (about 270 kgf / cm 2).2) Bending strength of at least 17.64 kJ / m2(18kgf · cm / cm2), More preferably a bending strength of at least 28 MPa and at least 19 kJ / m.2It has the impact strength of.
[0026]
The mixing ratio of the fiber for reinforcing concrete into the concrete molded body can be arbitrarily selected according to the performance, function, and application of the target concrete molded body, but is generally 0 with respect to the hydraulic composition containing cement. The blending ratio is desirably 0.05 to 20% by weight, and more desirably 0.1 to 10% by weight. In addition, other fibers may be used in combination as reinforcing fibers. Examples of fibers that can be used in combination include natural fibers such as pulp, and synthetic fibers such as PVA fibers, acrylic fibers, and polyarylate fibers. Further, fine aggregate and coarse aggregate can be used in combination, and examples thereof include sand, gravel, crushed stone and the like.
[0027]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[0028]
Various physical properties were measured according to the following methods.
Q value (molecular weight distribution): “PSKgel GMH6-HT” (trade name) manufactured by Tosoh Corporation was used as a column by gel permeation chromatography (GPC), and “GPC-” manufactured by Waters Co., Ltd. was used as a measuring device. Using "150C type" (trade name), a test specimen (polypropylene resin) was dissolved in o-dichlorobenzene so that its concentration was 0.05 wt%, and the resulting solution was measured at a temperature of 135 ° C. And asked.
IPF (isotactic pentad fraction): “JNM GX-270 type” (trade name) manufactured by JEOL Ltd., Macromolecules,6, 925 (1973),13It calculated | required by the C-NMR spectrum method.13In the C-NMR spectrum, a peak fraction corresponding to an isotactic bond was determined from a peak indicating five consecutive propylene monomer units. The assignment of peaks is Macromolecules,8687 (1975).
Effective draw ratio: Calculated from the formula of undrawn yarn fineness / drawn yarn fineness.
Single yarn strength: Performed according to JIS L 1015.
Young's modulus: Calculated by analyzing the results of single yarn strength measurement.
Pulling resistance against concrete: 1 cm of reinforcing fiber is embedded in a molded body obtained by mixing water and ordinary Portland cement at a weight ratio of water / cement = 1/3. This was cured in water at 25 ° C. for 28 days to obtain a concrete compact. Next, the reinforcing fiber was pulled out from the concrete at a speed of 20 mm / min, and the maximum pulling load at that time was defined as the resistance against pulling out of the concrete.
Fiber reinforced concrete molded body: water, ordinary Portland cement and reinforcing fiber are mixed at a weight ratio of water / cement / fiber = 1/3 / 0.03, compressed by pressure of 1176 N (120 kgf) for 10 seconds, 1 A molded body having a size of 30 cm × 25 cm × 1.1 cm was obtained. This was cured in steam at 60 ° C. for 5 hours and then left indoors for 28 days to obtain a concrete molded body.
Bending test: performed according to JIS A 1408 (1995-1-1).
Impact test: Performed according to JIS B 7722 (1995-1-1).
[0029]
Example 1
As the polypropylene resin, isotactic polypropylene manufactured by Chisso Co., Ltd. having a Q value of 3.2 and an IPF of 96 mol% (trade name “Tissopolypro CS3540”, melting point 165 ° C.) is used, and this is used at a spinning temperature of 320 ° C. An undrawn yarn was obtained by melt spinning. Using the obtained undrawn yarn, in a hot air tank consisting of a heater and a circulation fan, it is drawn at a magnification of 90% of the breaking draw ratio, and a roller made of a higher fatty acid metal salt, potassium oleate, as a fiber finish. 1.0% by weight was attached by the method to obtain a drawn yarn. The drawing line speed at this time was 50 m / min, and the hot air bath temperature was 143 ° C. The obtained drawn yarn was cut into 5 mm to obtain a high-strength polyolefin fiber. Table 1 shows the properties of the polypropylene resin used and the resulting high-strength polyolefin fibers. Using this high-strength polyolefin fiber as a fiber for reinforcing concrete, the fiber was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0030]
Example 2
Using the undrawn yarn obtained in Example 1, two-stage drawing was performed. The first stage of stretching is a heating roll at 90 ° C. and stretched at a ratio of 60% of the breaking stretch ratio, and the second stage of stretching is 90% of the breaking stretch ratio in a hot air bath at a hot air temperature of 138 ° C. Stretched at a magnification, and 1.0% by weight of oleic acid potassium salt, which is a higher fatty acid metal salt, was adhered as a fiber finish by a roller method to obtain a stretched yarn. The properties of the obtained high strength polyolefin fiber are shown in Table 1. Using this high-strength polyolefin fiber as a fiber for reinforcing concrete, the fiber was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0031]
Example 3
Using the undrawn yarn obtained in Example 1, two-stage drawing was performed. The first stage of stretching is performed in a hot air bath at a hot air temperature of 143 ° C. at a rate of 60% of the breaking stretch ratio, and the second stage of stretching is performed in a hot air bath at a hot air temperature of 143 ° C. The fiber was stretched at a magnification of 90%, and potassium oleate, which is a higher fatty acid metal salt, was attached as a fiber finish by 1.0% by weight using a roller method to obtain a stretched yarn. The properties of the obtained high strength polyolefin fiber are shown in Table 1. Using this high-strength polyolefin fiber as a fiber for reinforcing concrete, the fiber was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0032]
Example 4
As a polypropylene resin, isotactic polypropylene manufactured by Chisso Corporation having a Q value of 3.8 and an IPF of 94 mol% (trade name “Tissopolypro RS2514”, melting point 165 ° C.) is used at a spinning temperature of 320 ° C. An undrawn yarn was obtained by melt spinning. Using the obtained undrawn yarn, olein, which is a higher fatty acid metal salt as a fiber finish, is drawn at a ratio of 90% of the breaking draw ratio in a hot air bath having a hot air temperature of 143 ° C. used in Example 1. An acid potassium salt was attached by 1.0% by a roller method to obtain a drawn yarn. The properties of the obtained high strength polyolefin fiber are shown in Table 1. Using this high-strength polyolefin fiber as a fiber for reinforcing concrete, the fiber was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0033]
Example 5
Using the undrawn yarn obtained in Example 4, two-stage drawing was performed. The first stage of stretching is a hot water bath at 90 ° C. and stretched at a rate of 60% of the breaking stretch ratio, and the second stage of stretching is a ratio of 90% of the breaking stretch ratio in a hot air bath at a hot air temperature of 138 ° C. Then, 1.0% by weight of potassium oleate, which is a higher fatty acid metal salt, was attached as a fiber finish by a roller method to obtain a drawn yarn. Table 1 shows the properties of the obtained high-strength polyolefin fiber. Using this high-strength polyolefin fiber as a fiber for reinforcing concrete, the fiber was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of the molded body.
[0034]
Comparative Example 1
As a polypropylene resin, isotactic polypropylene (trade name “Cisso Polypro RS2236”, melting point 162 ° C.) manufactured by Chisso Corporation having a Q value of 7.2 and an IPF of 90 mol% is used. An undrawn yarn was obtained by melt spinning. Using the obtained undrawn yarn, it was drawn with a heating roll at 90 ° C. at a ratio of 90% of the breaking draw ratio, and a potassium oleate salt, which is a higher fatty acid metal salt, was used as a fiber finishing agent by a roller method. A stretched yarn was obtained by attaching a weight percentage. The obtained drawn yarn was cut into 5 mm to obtain a high-strength polyolefin fiber. Table 1 shows the properties of the polypropylene resin used and the high-strength polyolefin fiber. Further, the obtained high-strength polyolefin fiber was used as a concrete reinforcing fiber, and was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0035]
Comparative Example 2
Using the unstretched yarn obtained in Comparative Example 1 and stretching at 90% of the breaking stretch ratio in a 90 ° C warm water bath, roller oleic acid potassium salt, which is a higher fatty acid metal salt, is used as a fiber finish. 1.0% by weight was attached by the method to obtain a drawn yarn. The properties of the obtained high strength polyolefin fiber are shown in Table 1. Using this high-strength polyolefin fiber as a fiber for reinforcing concrete, the fiber was produced according to the above-described method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0036]
Comparative Example 3
Using the undrawn yarn obtained in Example 1, two-stage drawing was performed. The first stage of stretching is a hot roll at 120 ° C. and stretched at a ratio of 60% of the breaking stretching ratio, and the second stage of stretching is a hot roll at 120 ° C. and stretched at a ratio of 90% of the breaking stretch ratio. Then, 1.0% by weight of potassium oleate, which is a higher fatty acid metal salt, was attached as a fiber finish by a roller method to obtain a drawn yarn. The properties of this polyolefin fiber are shown in Table 1. Moreover, using the obtained polyolefin fiber as a fiber for concrete reinforcement, it manufactured according to the above-mentioned concrete molded object manufacturing method, and obtained the concrete molded object. Table 1 shows the characteristics of this molded body.
[0037]
Comparative Example 4
Using the undrawn yarn obtained in Example 1, two-stage drawing was performed. The first stage of stretching is stretched at a rate of 60% of the breaking stretch ratio in a 90 ° C hot water bath, and the second stage of stretching is stretched at a ratio of 90% of the breaking stretch ratio with a 130 ° C hot roll. Then, 1.0% by weight of potassium oleate, which is a higher fatty acid metal salt, was attached as a fiber finish by a roller method to obtain a drawn yarn. The properties of the obtained polyolefin fiber are shown in Table 1. Using this polyolefin fiber as a fiber for reinforcing concrete, it was produced in accordance with the above-mentioned method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0038]
Comparative Example 5
In accordance with the conditions of the examples of JP-A-2000-64116, as a polypropylene resin, an isotactic polypropylene manufactured by Chisso Corporation having a Q value of 3.2 and an IPF of 96 mol% (trade name “Tissopolypro CS3540”, melting point 165 ° C.), and this was placed in the core component, and low-density polyethylene (trade name “Petrocene PE350”, melting point 107 ° C.) manufactured by Tosoh Corporation was placed in the sheath component and melt-spun. The drawn yarn was drawn in one stage with a 60 ° C. hot roll, and 1.0% by weight of potassium oleate, which is a higher fatty acid metal salt, was attached as a fiber finish by a roller method to obtain a drawn yarn. The fiber surface of the obtained fiber had irregularities composed of a convex part where the sheath component was raised and a concave part which was not raised. Table 1 shows the properties of the used polypropylene resin and the obtained polyolefin fibers. Using this polyolefin fiber as a fiber for reinforcing concrete, it was produced in accordance with the above-mentioned method for producing a concrete molded body to obtain a concrete molded body. Table 1 shows the characteristics of this molded body.
[0039]
[Table 1]
As shown in Examples 1-5, by drawing in a hot air bath under non-contact overheating, it is possible to obtain a fiber having both the properties of a single yarn strength of 9 cN / dtex or more and a streaky rough surface structure. did it. FIG. 1 is an enlarged photograph obtained by observing the surface (side surface) of a high-strength polyolefin fiber according to the present invention, which was obtained in Examples. On the fiber surface, a streaky rough surface structure formed in the circumferential direction along the curved surface can be observed. Thus, when the fiber surface is a rough structure, the anchor effect with respect to a concrete matrix improves, and it has a drawing resistance against concrete of 12 cN or more. Further, when this polyolefin fiber is used as a fiber for reinforcing concrete, the concrete molded body is 26.5 MPa (270 kgf / cm2) The above bending strength and 17.64 kJ / m2(18kgf · cm / cm2) The above-mentioned impact strength was exhibited, a high concrete reinforcing effect was exhibited, and it was found that the obtained concrete molded body was excellent in mechanical properties.
[0041]
In contrast, the polyolefin fibers obtained by the production methods shown in Comparative Examples 1 to 4 had low single yarn strength, and the fiber surface structure was smooth. When this polyolefin fiber was used as a concrete reinforcing fiber, a sufficient reinforcing effect could not be exhibited, for example, the fiber was removed from the concrete matrix. Further, the fiber shown in Comparative Example 5 had a rough surface structure with an uneven fiber surface, but the single yarn strength was remarkably low. When this polyolefin fiber is used as a fiber for reinforcing concrete, the fiber breaks due to its low single yarn strength, and the mechanical properties of the concrete molded body are low in bending strength and impact strength, and a sufficient concrete reinforcing effect is obtained. I couldn't.
[0042]
【The invention's effect】
The high-strength polyolefin fiber of the present invention has a streaky rough surface structure formed along the curved surface of the fiber surface and has high strength, so that the physical bonding strength with the concrete matrix is large, and the concrete reinforcing effect It is extremely excellent. In addition, the concrete molded body of the present invention is excellent in bending strength and impact strength because it is filled with high-strength polyolefin fibers having a high single yarn strength and a large physical bond strength with the concrete matrix.
[Brief description of the drawings]
FIG. 1 is an electron micrograph (× 2000 magnification) when the surface (side surface) of a high-strength polyolefin fiber is observed with an electron microscope.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002096780A JP3960100B2 (en) | 2002-03-29 | 2002-03-29 | High strength polyolefin fiber and concrete molded body using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002096780A JP3960100B2 (en) | 2002-03-29 | 2002-03-29 | High strength polyolefin fiber and concrete molded body using the same |
Publications (2)
| Publication Number | Publication Date |
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| JP2003293216A JP2003293216A (en) | 2003-10-15 |
| JP3960100B2 true JP3960100B2 (en) | 2007-08-15 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7074483B2 (en) * | 2004-11-05 | 2006-07-11 | Innegrity, Llc | Melt-spun multifilament polyolefin yarn formation processes and yarns formed therefrom |
| CN100357505C (en) * | 2005-06-27 | 2007-12-26 | 江苏泽天化纤有限公司 | High strength and low extending thick Denier polypropylene yarns and production thereof |
| AU2006297004B2 (en) * | 2005-09-30 | 2011-11-24 | Eidgenossische Materialprufungs Und Forschungsanstalt | Bi-component synthetic fibres for application in cement-bonded building materials |
| JP4834688B2 (en) * | 2007-03-26 | 2011-12-14 | 株式会社クラレ | Polypropylene fiber with excellent heat resistance |
| WO2008123173A1 (en) | 2007-03-26 | 2008-10-16 | Kuraray Co., Ltd. | Polypropylene fiber, method of producing the same and utilization of the same |
| JP4820836B2 (en) * | 2007-03-27 | 2011-11-24 | 株式会社クラレ | Polypropylene fiber |
| JP4990827B2 (en) * | 2007-09-10 | 2012-08-01 | 株式会社クラレ | Hydraulic composition and cured product |
| WO2013089175A1 (en) * | 2011-12-13 | 2013-06-20 | ダイワボウホールディングス株式会社 | Fibers for cement reinforcement, method for producing same and cement hardened body |
| US9228122B2 (en) * | 2013-06-05 | 2016-01-05 | Halliburton Energy Services, Inc. | Methods and cement compositions utilizing treated polyolefin fibers |
| EP3327189A4 (en) | 2015-07-24 | 2018-07-18 | Mitsubishi Chemical Corporation | Polypropylene fiber and method for manufacturing polypropylene fiber |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS61102415A (en) * | 1984-10-19 | 1986-05-21 | Teijin Ltd | Polyester fiber and its production |
| JP2537962B2 (en) * | 1988-04-21 | 1996-09-25 | 株式会社クラレ | Polyvinyl alcohol fiber suitable for reinforcement |
| JP2537313B2 (en) * | 1991-07-02 | 1996-09-25 | 大和紡績株式会社 | Polypropylene fibers and composite fibers |
| JPH10212619A (en) * | 1997-01-23 | 1998-08-11 | Kuraray Co Ltd | Fiber and formed material by using the fiber |
| JP3351724B2 (en) * | 1997-10-07 | 2002-12-03 | 萩原工業株式会社 | Polypropylene fiber for cement reinforcement and construction method of shotcrete using the same |
| JP3130288B2 (en) * | 1997-10-24 | 2001-01-31 | 宇部日東化成株式会社 | Stretching method and stretched product |
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