JP3849814B2

JP3849814B2 - Fiber assembly molded product and method for producing the same

Info

Publication number: JP3849814B2
Application number: JP18865596A
Authority: JP
Inventors: 一恒菊田; 勲新庄; 璋明波根
Original assignee: Chisso Corp
Current assignee: JNC Corp
Priority date: 1996-06-28
Filing date: 1996-06-28
Publication date: 2006-11-22
Anticipated expiration: 2016-06-28
Also published as: JPH1014569A

Description

【０００１】
【発明の属する技術分野】
本発明は、特に、濾過材、汚水浄化材等として好適に利用される繊維集合体成形物及びその製造法に関するものである。
【０００２】
【従来の技術】
従来、浮遊物や懸濁物を含む溶液の濾過材としては、濾紙、濾布、金網、砂、セラミック等が用いられてきたが、濾紙、濾布、金網等は濾過する液体中の浮遊物や懸濁物が表面に付着して目詰まりを起こす。その結果、濾過速度が低下し、その濾過効率が悪くなる。また、砂やセラミック等を利用した粒子状物の堆積層による濾過層を用いた場合では、濾過速度の低下は小さいものの濾過精度に限界があり、濾液の透明度が悪いという面で問題が生じ、しかも逆流洗浄も困難である。
【０００３】
このような欠点を解消する提案として特公昭６２ー１１６３７号公報には複数本の無捲縮短繊維を絡み合わせた繊維塊からなる水処理材が開示されている。これは濾過面積を大きくする事により、濾過効果の改善を計ったものであるが、この繊維塊は短繊維が単に相互に絡まりあったものであるため、長時間使用したり、逆流洗浄時には繊維塊がばらけて短繊維の流出、強いては濾過効果が大きく低下するという問題があった。
【０００４】
また、特開平４ー２７４９５号公報には繊維径が１〜２０デニール、繊維長３〜５０ｍｍの短繊維を水槽内で投入し攪拌することにより短繊維同士を絡み合わせて、集合させた後、部分的に融着して得られた繊維塊からなる水処理材が開示されている。この繊維塊は製造工程上同じ繊維（太さや長さ）を用いても繊維の絡まり度合いにより繊維塊の個々の大きさや空隙率等がバラついたまちまちなものになり、製品として濾過性能が異なる為に取扱いづらい。しかも、この方法で得られた繊維塊は、繊維塊の中心部が密になっている為に、逆流洗浄の際に、捕捉した懸濁物質の除去が十分に行われず、従って長時間に渡って濾過性能を維持することが困難であった。
【０００５】
【発明が解決しようとする課題】
本発明は、空隙率が高く、外圧に対して形状保持性の高い繊維集合体成形物であり、特に、長時間の使用においても形状保持率が大きく、繊維の流失のない、懸濁物質の濾過効率が高く、かつ逆流洗浄時には捕集した懸濁物質の除去率の高い水処理濾材に有用な繊維集合体成形物及びその製造法を提供することを目的する。
【０００６】
【課題を解決するための手段】
本発明者らは、上記課題を解決するべく鋭意研究を重ねた結果、下記の繊維集合体成形物を用いることにより所期の目的が達成されることを見いだし、本発明を完成するに至った。本発明は、下記の構成を有する。すなわち、本発明は、（１）単糸繊度が１０〜１００デニールで、繊維長が３８〜１０５ｍｍであり、かつ捲縮を有している熱可塑性複合短繊維が集合した繊維塊からなり、該繊維塊を構成する前記熱可塑性複合短繊維が三次元方向に分散されて絡まり合い、かつ該短繊維同士の接合点が融着接合されている繊維集合体成形物であって、空隙率が９０〜９８％で、外圧に対する形状保持率が８５％以上であることを特徴とする繊維集合体成形物。
（２）熱可塑性複合短繊維が、単糸繊度が２０〜６０デニールであり、繊維長が４５〜７８ｍｍである熱可塑性複合短繊維である前記（１）項に記載の繊維集合体成形物。
（３）熱可塑性複合短繊維が、平均比重が１．０〜１．５ｇ／ｃｍ³である熱可塑性複合短繊維である前記（１）または（２）項に記載の繊維集合体成形物。
（４）熱可塑性複合短繊維が、高融点樹脂を芯成分に配し、該高融点樹脂の融点よりも１５℃以上低い融点を有する低融点樹脂を鞘成分に配した鞘芯型構造を有する熱可塑性複合短繊維である前記（１）〜（３）項のいずれかに記載の繊維集合体成形物。
（５）単糸繊度が１０〜１００デニールであり、繊維長が３８〜１０５ｍｍであり、かつ捲縮を有する熱可塑性複合短繊維集合体を、空隙率が９０〜９８％の繊維塊に加工した後に熱処理することを特徴とする前記（１）に記載の繊維集合体成形物の製造法。
（６）熱可塑性複合短繊維集合体が、熱可塑性複合繊維の集束されたスライバーを所定の長さに切断したものである前記（５）項に記載の繊維集合体成形物の製造法。
（７）熱可塑性複合短繊維が、高融点樹脂を芯成分に配し、該高融点樹脂の融点よりも１５℃以上低い融点を有する低融点樹脂を鞘成分に配した鞘芯型構造を有する熱可塑性複合短繊維である前記（５）項または（６）項に記載の繊維集合体成形物の製造法。
（８）熱処理を、熱可塑性複合短繊維の低融点樹脂の融点以上であり、高融点樹脂の融点以下である温度で行う前記（７）項に記載の繊維集合体成形物の製造法。
（９）熱可塑性複合短繊維集合体を球状に加工することを特徴とする前記（５）〜（８）項のいずれかに記載の繊維集合体成形物の製造法。
【０００７】
以下、本発明について詳細に説明する。本発明で言う繊維重合体成形物とは、単糸繊度が１０〜１００デニール、繊維長３８〜１０５ｍｍの捲縮を有する熱可塑性繊維が三次元方向に分散、絡まりあって、短繊維同士の接合点が融着接合された構造からなっている。繊維集合体成形物の内部は、捲縮の発現した繊維の分散と絡まりにより９０〜９８％、好ましくは９５〜９８％の高空隙率を保持した微細な多孔質構造を有している。この微細な多孔質構造は汚水中の懸濁物質（以下ＳＳと略記する）を捕捉し、汚水の自己浄化を促進する好気性微生物の侵入や着床を助け、その増殖作用を助成するのに適している。空隙率が９０％未満では繊維が過密になりＳＳの捕捉や好気性微生物の着床に悪影響を与え、浄化作用が低下する。また、逆流洗浄時に繊維集合体成形物から一度捕捉したＳＳが完全に除去されにくいため、使用頻度を増すとともに濾過効率は大きく低下してくる。一方、空隙率が９８％を越えると、繊維集合体成形物が粗となるため、濾過効率が劣るものとなる。
【０００８】
本発明の繊維集合体成型物に用いる熱可塑性複合繊維は、融点差１５℃以上有する低融点樹脂と高融点樹脂で構成される。高融点樹脂としては、例えばポリエステル、ポリアミド、ポリフェニレンサルファイド、ポリプロピレン等があげられ、また、低融点成分としてはポリプロピレン、高密度ポリエチレン、低密度ポリエチレン、線状低密度ポリエチレン、αーオレフィン共重合体、低融点ポリエステル（イソフタル酸共重合ポリエステル）等があげられ、融点差が１５℃以上有すれば組み合わせは、特に限定されるものではなく、目的とする作用効果を妨げない範囲で任意に選択できる。融点差が１５℃未満では接着加工時の管理上の困難さから熱接着が不十分になり易く、結果として濾過、逆流洗浄時に短繊維が流失し好ましくない。
熱可塑性複合繊維の構造としては、前記低融点樹脂を鞘成分とし、高融点樹脂を芯成分とする鞘芯型構造で、繊維断面における芯成分の位置が同心しているいわゆる鞘芯同心型構造や、繊維断面における芯成分の位置が偏心しているいわゆる鞘芯偏心型構造、または芯成分を複数本以上配置した海島型構造、または低融点樹脂と高融点樹脂の並列型構造等が用いられるが、絡み合った短繊維同士の接合点の融着接合をより効果的に行うためにも低融点樹脂で高融点樹脂が全面被覆された鞘芯型構造が好ましい。
該複合繊維において、低融点樹脂と高融点樹脂の複合比は１０／９０〜９０／１０（重量比）、より好ましくは３０／７０〜７０／３０（重量比）である。低融点樹脂が１０重量％未満の場合は、短繊維同士の接合点の融着接合が不充分となり、繊維集合体成型物の形状保持率が低下する。また、９０重量％をこえると、多孔質構造の形成が困難となる。
【０００９】
本発明に用いられる熱可塑性複合繊維の平均比重は特に限定されないが、好ましくは１．０〜１．５ｇ／ｃｍ^３、さらに好ましくは１．１〜１．４ｇ／ｃｍ^３である。本発明の繊維集合体成型物を濾過材に用いた場合、該成型物を構成している熱可塑性複合繊維の平均比重が１．０ｇ／ｃｍ^３未満では濾過時に浮遊し濾過効率が低下する。また、平均比重が１．５ｇ／ｃｍ^３を越えると逆流洗浄時のエアレーションの負荷増加及び交換時の作業性から好ましくない。なお、前記の熱可塑性複合繊維に比重を調整するために本発明の効果を妨げない範囲においてタルク、炭酸カルシウム、マイカ等の無機フィラを含んでも良い。
【００１０】
本発明に用いられる熱可塑性複合繊維は、単糸繊度が１０〜１００デニールであり、好ましくは２０〜６０デニール、より好ましくは２５〜５０デニールである。また、繊維長は３８〜１０５ｍｍであり、好ましくは４５〜７８ｍｍである。単糸繊度が１０デニール未満では、形状保持性がやや劣り、例えば、濾過材として用いた場合に、逆流洗浄時のＳＳの除去が不十分となり、濾過効率が劣るようになる。また、１００デニールを越えると絡み合った空間が大きくなりすぎて濾過効率が劣るものになる。一方、繊維長が３８ｍｍ未満になると短繊維が集束されたスライバーを作る事が困難であり、１０５ｍｍを越えると繊維集合体成形物が密になり、濾過効率が悪いものになる。捲縮は、本発明の繊維集合体成形物にとって重要な意味を持つ。つまり、繊維塊中の短繊維は三次元方向に分散され、絡み合うが、捲縮を有することにより繊維同士の絡みが促進され複雑な網目状の三次元構造の絡みになるのである。鞘芯型構造のうち、特に鞘芯偏芯型構造の場合は低融点樹脂と高融点樹脂の収縮差による潜在捲縮を発現させて絡み合わせることもできる。更には、この潜在捲縮の発現と機械捲縮付与による顕在捲縮の両方を利用することができる。特に後者の場合は、潜在捲縮によるスパイラル捲縮と機械捲縮付与によるジグザク捲縮の両方が混在した一層複雑な三次元捲縮が発現するので繊維塊の中に形成される多孔質構造も複雑な三次元の深層網目状多孔質構造の繊維塊となる。かかる繊維塊からなる繊維集合体成形物は浄化処理材等として使用すると、前述した懸濁物質の捕捉を促進し、好気性微生物の侵入が容易となり、一層着床箇所が増加するので、その増殖が活発となり浄化作用が向上する。その捲縮数はカード通過性を考慮したスライバー作製可能な範囲であって、５〜２０山／２５ｍｍが好ましく、特に好ましくは８〜１６山／２５ｍｍである。捲縮を付与する方法としてはスタフィングボックス法またはギヤー式クリンパー等公知の方法を利用することができ、捲縮形態もスパイラル状、ジグザク状等、特に限定されない。
【００１１】
本発明の繊維集合体成形物は、このような多孔質構造を有する繊維塊からなり、該繊維塊において、絡み合った繊維の接合点が融着接合された結果、得られた繊維集合体成形物中で外内層共に短繊維がほぼ均等に分散絡合し、空隙率が９０〜９８％であり、かつ微細な空隙を保持した多孔質構造が得られるのである。
本発明の繊維集合体成型物は、このような多孔質構造を有するため、外圧に対して形状保持率が極めて高く、特に本発明の繊維集合体成形物を濾過材として用いたときには、水圧に対して形状保持率が極めて高いので前述した好気性微生物の進入や着床を保持し、コンスタントな増殖作用を長期間に亘って促進しうるのである。また、逆流洗浄時にもほとんど変形することなく形状を保持した状態で捕集した懸濁物質の除去が可能となり、再生利用にも大きく寄与するのである。高い形状保持率は複合短繊維の剛性に大きく依存するが、濾過材として用いた場合も、連続して行われる撹拌などの水流外圧抵抗に耐える剛性は繊維によって変わるが、繊度としては１０〜１００デニ−ルが適している。
【００１２】
本発明の繊維集合体成形物を製造するにあたり、その製造法は特に限定されないが、例えば、以下のような方法で製造することが可能である。単糸繊度が１０〜１００デニールの熱可塑性複合繊維のトウをスタフィングボックス等で所定数の機械捲縮を付与した後、繊維長３８〜１０５ｍｍに切断して開繊したウエブを適当量採取して丸めて繊維塊に加工することもできるが、繊維塊に際して好ましい態様は、前記開繊ウエブを集束して一度スライバ−を形成した後、切断機でスライバーを所定の長さに切断し、熱可塑性複合短繊維集合体を形成したのち、これを上下及び／または左右からの接触回転運動で球状繊維塊に加工するのである。
このようにして加工された球状繊維塊は、該繊維塊内部の空隙が微細な、空隙率が９０〜９８％の多孔質構造体となる。この方法によれば、好気性微生物の増殖に適した空隙率の高い繊維集合体成形物をより効率よく得ることができる。
次に、繊維塊を、該繊維塊を構成する複合短繊維の一方の成分が軟化または融解する温度で熱処理する。球状になった繊維塊については、特に、熱処理を前記温度範囲のもとで、熱風ドライヤ−、熱風循環炉等の熱処理装置を用いて下方から熱風を球状繊維塊に吹き付けて行うことが好ましい。この状態で球状繊維塊を、金網等の移動ベルト上で熱風圧の調整によって、浮遊運動させながら短繊維同士の接合点を融着接合させるのである。熱処理は熱処理時間と温度とのバランスで調整することができる。特に球状繊維塊を得るのに最適な、繊維塊を浮遊させながら行う前記熱処理は、隣接する繊維塊同士の融着結合を生じずに、供給前の球状の形状を維持したまま、繊維塊内部で複合短繊維の繊維接合点が熱融着接合することができる結果、得られる繊維集合体成形物は、その成形物の外内層共に短繊維が非常に均質に分散し絡み合った三次元網目構造を生じる点で好ましい。この三次元網目構造によって、空隙率が高く、例えば、水流等の外圧に対してもほとんど変形することなく、高い形状保持率を有することができる。そして、本方法によれば、空隙率が９０〜９８％の繊維集合体成形物をより効率よく得ることができる。かかる製造法で得られる多孔質構造の繊維集合体成形物は例えば水処理材として用いた場合に、その使用時や逆流洗浄時にも繊維の脱落、流失などが生じることがないという優れた効果を奏するのである。
外圧に対する形状保持性は種々の方法で表現されうるが、本発明では、底部に多孔板を有し、高さが２００ｃｍで、内径が５０ｃｍである濾過器内に６０ｃｍの高さまで繊維集合体成形物を充填したのち、原水を濾過器内に満たしたときの前記繊維集合体成形物の高さ（Ｈ１）を測定し、原水を濾過速度６０ｍ／ｈで２４時間通水した後の前記繊維集合体成形物の高さ（Ｈ２）を測定し、これらの測定値から、下式により求めた値を外圧に対する形状保持性の指標として、「形状保持率」として定義した。
形状保持率（％）=（Ｈ２／Ｈ１）×１００
本発明の繊維集合体成形物は、該形状保持率が８５％以上であるときに、外圧に対する抵抗力が好ましく、例えば、これを濾過材として使用したときには、使用頻度とともに目詰まりし濾過効率の低下をきたす従来の濾過材に比べて、空隙の大きさが維持されるために良好な濾過効率を長期的に維持できるという優れた性能を発揮する。
本発明の繊維集合体成形物の大きさは、種々の用途と目的において任意に選択され特に限定されるものではない。球状の繊維集合体成形物を濾過材として使用する場合にもその大きさは任意に選択でき、例えば、平均直径が２０〜３０ｍｍのものを選択できる。
【００１３】
【実施例】
次に本発明を実施例及び比較例により説明するが、本発明はこれらの実施例に限定されるものではない。尚、各実施例に用いた測定法を以下に示す。
［空隙率］
繊維集合体成形物の見かけの比重Ｓ₁（ｇ／ｃｍ³）と該成形体を構成している複合短繊維の比重Ｓ₂（ｇ／ｃｍ³）から、次式により求めた。
空隙率（％）＝（Ｓ₂ーＳ₁）×１００／Ｓ₂
［ＳＳの残留率］
濾過使用前の繊維塊の重量Ｗ₁（ｇ／５０個）と逆流洗浄後の繊維塊の乾燥後の重量Ｗ₂（ｇ／５０個）を測定し、ＳＳの残留率を求めた。
ＳＳ残留率（％）＝（Ｗ₂−Ｗ₁）×１００／Ｗ₁
［短繊維の脱落度合］
逆流洗浄後の洗浄水中に流失して脱落した繊維の有り／無しで判定した。
［形状保持率］
底部に多孔板を有し、高さが２００ｃｍで、内径が５０ｃｍである濾過機内に６０ｃｍの高さまで繊維集合体成形物を充填したのち、原水を濾過機内に満たしたときの前記繊維集合体成形物の高さ（Ｈ１）を測定し、原水を濾過速度６０ｍ／ｈで２４時間通水した後の前記繊維集合体成形物の高さ（Ｈ２）を測定し、下式により形状保持率を求めた。該形状保持率の値から、下記の基準で形状保持性能を評価した。
形状保持率（％）=（Ｈ２／Ｈ１）×１００
判定基準
○ ：９０％以上
△ ：８０％以上９０％未満
× ：８０％未満
（実施例１）
融点１２６℃の高密度ポリエチレンを鞘成分とし、融点２５６℃のポリエステルを芯成分とし、鞘芯複合比６０／４０（重量比）、単糸繊度３２デニール、１０山／２５ｍｍのジグザグ捲縮を有する繊維長５０ｍｍの鞘芯同心型複合短繊維をカ−ド機に通し、得たウエッブを収束し総繊度８万デニールのスライバーを得た。このスライバーを２８ｍｍに切断し、ボール状になるように丸めた後、１４０℃に調整された金網コンベアー式熱風循環ドライヤーに移し、金網コンベアーの下方から１４０℃の熱風を吹き付けて球状繊維塊に浮遊運動を与えながら、２０秒間熱処理をした。得られた繊維集合体成形物は、平均直径２５ｍｍで、空隙率が９７％、該成形物を構成している前記複合短繊維の平均比重が１．２ｇ／ｃｍ³の多孔質構造であった。この成形物を、底部に多孔板を有し、高さ２００ｃｍ、内径５０ｃｍの濾過機内に６０ｃｍの高さまで充填し、濾過器上部から活性汚泥処理した原水を濾過速度６０ｍ／ｈｒで２４時間通水し、その一定時間毎に原水と処理水を採取し，ＳＳ及びＢＯＤの測定を行い、その平均値を求めた。また、２４時間通水後、濾過機多孔板の下部から空気の吹き込み、及び洗浄水を流入して逆流洗浄を１時間行い、逆洗水中の繊維の脱落の度合いを調べた結果、殆ど繊維の脱落は見られなかった。また、逆流洗浄後の繊維集合体成型物に残留付着しているＳＳ量はほとんど見られなかった。その結果を第１表に示す。
【００１４】
（実施例２）
融点１２６℃の高密度ポリエチレンを鞘成分とし、融点２５６℃のポリエステルを芯成分とし、鞘芯複合比５０／５０（重量比）、単糸繊度６０デニール、１０山／２５ｍｍのジグザグ捲縮を有する繊維長３８ｍｍの鞘芯同心型複合短繊維を用いた以外は実施例１と同様にして、多孔質構造の球状の繊維集合体成形物（空隙率９３％、該成形物を構成している前記複合短繊維の平均比重１．２ｇ／ｃｍ³）を得た。得られた繊維集合体成形物を水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００１５】
（実施例３）
融点１２６℃の高密度ポリエチレンを鞘成分とし、融点２５６℃のポリエステルを芯成分とし、鞘芯複合比８０／２０（重量比）、単糸繊度２５デニール、１４山／２５ｍｍのジグザグ捲縮を有する繊維長６４ｍｍの鞘芯同心型複合短繊維を用いた以外は実施例１と同様にして、多孔質構造の球状の繊維集合体成形物（空隙率９８％、該成形物を構成している前記複合短繊維の平均比重１．１ｇ／ｃｍ³）を得た。得られた繊維集合体成形物を水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００１６】
（実施例４）
融点２００℃のイソフタル酸共重合ポリエチレンテレフタレートを鞘成分とし、融点２５６℃のポリエステルを芯成分とし、鞘芯複合比６０／４０（重量比）、単糸繊度１０デニール、１０山／２５ｍｍのジグザグ捲縮を有する繊維長５４ｍｍの鞘芯同心型複合短繊維を用い、熱風ドライヤーで２１０℃、３分間熱処理をした以外は実施例１と同様にして、多孔質構造の球状の繊維集合体成形物（空隙率９６％、該成形物を構成している前記複合短繊維の平均比重１．４ｇ／ｃｍ³）を得た。得られた繊維集合体成形物を水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００１７】
（実施例５）
実施例２において、複合短繊維を鞘芯偏心型にした以外は全て実施例２と同様にして多孔質構造の球状の繊維集合体成形物（空隙率９５％、該成形物を構成している前記複合短繊維の平均比重１．２ｇ／ｃｍ³）を得た。尚、捲縮は１６山／２５ｍｍでジグザグ構造とスパイラル構造が顕在したものであった。得られた繊維集合体成形物を水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００１８】
（実施例６）
実施例３において、単糸繊度９０デニール、８山／２５ｍｍのジグザグ捲縮を有する繊維長７２ｍｍの鞘芯同心型複合短繊維を用いた以外は実施例３と同様にして多孔質構造の球状の繊維集合体成形物（空隙率９８％、該成形物を構成している前記複合短繊維の平均比重１．１ｇ／ｃｍ³）を得た。得られた繊維集合体成形物を水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００１９】
（比較例１）
融点１２６℃の高密度ポリエチレンを鞘成分とし、融点２５６℃のポリエステルを芯成分とし、鞘芯複合比６０／４０（重量比）、単糸繊度１５デニール、１０山／２５ｍｍのジグザグ捲縮を有する繊維長３０ｍｍの鞘芯同心型複合短繊維を用いた以外は実施例１と同様にして、平均直径が２５ｍｍで、球状である、本発明の繊維集合体成形物に相当するもの（空隙率が９６％、該成形物を構成している前記複合短繊維の平均比重１．２ｇ／ｃｍ³）を得た。該繊維集合体成形物に相当するものを水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００２０】
（比較例２）
実施例１で得た総繊度８万デニールのスライバーを６０ｍｍに切断し、ボール状になるように硬く丸めた以外は実施例１と同様にして、平均直径が２０ｍｍで、球状である本発明の繊維集合体成形物に相当するもの（空隙率８０％、該成形物を構成している前記複合短繊維の平均比重１．２ｇ／ｃｍ³）を得た。該繊維集合体成形物に相当するものを水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００２１】
（比較例３）
単糸繊度１１０デニール以外は実施例１と同様にして、平均直径が３０ｍｍで、球状である本発明の繊維集合体成形物に相当するもの（空隙率９０％、該成形物を構成している前記複合短繊維の平均比重１．２ｇ／ｃｍ³）を得た。該繊維集合体成形物に相当するものを水処理媒体として、実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００２２】
（比較例４）
単糸繊度１０デニール、繊維長３８ｍｍのポリプロピレン短繊維（融点１６０℃）と単糸繊度１０デニ−ル、繊維長３８ｍｍのポリエチレン（融点１２６℃）とを重量比５０／５０で混綿しカード機に通し、得たウエッブを収束し総繊度７万デニールのスライバーを得た。以下、実施例１と同様にして球状の本発明の繊維集合体成形物に相当するもの（空隙率９７％、該成形物を構成している前記短繊維の平均比重０．９４ｇ／ｃｍ³）を得た。該繊維集合体成形物に相当するものを実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００２３】
（比較例５）
比較例１において、単糸繊度５デニール、１８山／２５ｍｍのジグザグ捲縮を有する繊維長３８ｍｍの鞘芯同心型複合短繊維を用いた以外は、比較例１と同様にして本発明の繊維集合体成形物に相当するもの（空隙率９７％、該成形物を構成している前記複合短繊維の平均比重１．２ｇ／ｃｍ³）を得た。該繊維集合体成形物に相当するものを実施例１と同じ濾過試験を行った。その結果を第１表に示す。
【００２４】
（比較例６）
１２５℃の熱風ドライヤーで熱処理した以外実施例１と同様にして本発明の繊維集合体成形物に相当するもの（空隙率９７％）を得た。該繊維集合体成形物に相当するものを実施例１と同じ濾過試験を行ったが、短繊維は繊維同士の接合点の融着接合が不良のため濾過時にバラバラになった。
【００２５】
【表１】

【００２６】
【発明の効果】
本発明の繊維集束体成形物は、特に、水処理濾材として用いたとき、長時間の使用においても形状保持率が大きく、繊維の流失もなく、懸濁物質の濾過効率が高く、かつ逆流洗浄時には捕取した懸濁物質の除去率が高く、濾過効果に優れたものであり、しかも、容易に安価に製造できるものである。[0001]
BACKGROUND OF THE INVENTION
In particular, the present invention relates to a fiber aggregate molded article suitably used as a filter material, a sewage purification material, and the like, and a method for producing the same.
[0002]
[Prior art]
Conventionally, filter paper, filter cloth, wire mesh, sand, ceramics, etc. have been used as filter media for solutions containing suspended solids and suspensions, but filter paper, filter cloth, wire mesh, etc. are suspended substances in the liquid to be filtered. And suspended solids adhere to the surface and cause clogging. As a result, the filtration rate is lowered and the filtration efficiency is deteriorated. In addition, in the case of using a filtration layer by a particulate matter deposition layer using sand or ceramics, the decrease in filtration speed is small, but the filtration accuracy is limited, and problems arise in terms of poor transparency of the filtrate, Moreover, backwashing is difficult.
[0003]
As a proposal for eliminating such drawbacks, Japanese Patent Publication No. 62-11637 discloses a water treatment material comprising a fiber lump in which a plurality of uncrimped short fibers are intertwined. This is a measure to improve the filtration effect by increasing the filtration area, but this fiber lump is simply a short fiber entangled with each other, so it can be used for a long time or when backwashing There was a problem that the lump was scattered and the short fibers flowed out and the filtration effect was greatly reduced.
[0004]
In addition, in JP-A-4-27495, the fiber diameter is 1 to 20 denier, the short fibers having a fiber length of 3 to 50 mm are put in the water tank and stirred to intertwine the short fibers, and then assembled. A water treatment material composed of a fiber lump obtained by partially fusing is disclosed. Even if the same fiber (thickness or length) is used in the manufacturing process, the fiber lump varies in size, porosity, etc. depending on the degree of fiber entanglement, and the filtration performance differs as a product. It is difficult to handle. In addition, the fiber mass obtained by this method is dense at the center of the fiber mass, so that the trapped suspended solids are not sufficiently removed during the backwashing, and therefore it takes a long time. Therefore, it was difficult to maintain the filtration performance.
[0005]
[Problems to be solved by the invention]
The present invention is a fiber assembly molded product having a high porosity and a high shape retention property against external pressure, and in particular, a high shape retention rate even during long-term use, and there is no loss of fibers. An object of the present invention is to provide a fiber assembly molded article useful for a water treatment filter medium having a high filtration efficiency and a high removal rate of suspended substances collected during backwashing, and a method for producing the same.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the intended purpose is achieved by using the following fiber assembly molded product, and the present invention has been completed. . The present invention has the following configuration. That is, the present invention comprises (1) a fiber lump in which thermoplastic composite short fibers having a single yarn fineness of 10 to 100 denier, a fiber length of 38 to 105 mm, and having crimps are aggregated, A fiber assembly molded product in which the thermoplastic composite short fibers constituting the fiber mass are dispersed and entangled in a three-dimensional direction, and the joining points of the short fibers are fusion-bonded, and the porosity is 90 A fiber assembly molded product characterized in that the shape retention rate with respect to external pressure is 85% or more at ˜98%.
(2) The fiber assembly molded article according to (1), wherein the thermoplastic composite short fiber is a thermoplastic composite short fiber having a single yarn fineness of 20 to 60 denier and a fiber length of 45 to 78 mm.
(3) The fiber assembly molded article according to (1) or (2), wherein the thermoplastic composite short fibers are thermoplastic composite short fibers having an average specific gravity of 1.0 to 1.5 g / cm ³ .
(4) The thermoplastic composite short fiber has a sheath core type structure in which a high melting point resin is arranged in a core component and a low melting point resin having a melting point lower by 15 ° C. or more than the melting point of the high melting point resin is arranged in a sheath component. The fiber assembly molded product according to any one of (1) to (3), which is a thermoplastic composite short fiber.
(5) A single fiber fineness of 10 to 100 denier, a fiber length of 38 to 105 mm, and a crimped thermoplastic composite short fiber aggregate were processed into a fiber lump having a porosity of 90 to 98%. The method for producing a molded product of a fiber assembly according to (1), wherein the heat treatment is performed later.
(6) The method for producing a fiber assembly molded product according to (5) above, wherein the thermoplastic composite short fiber aggregate is obtained by cutting a sliver in which the thermoplastic composite fibers are gathered into a predetermined length.
(7) The thermoplastic composite short fiber has a sheath core type structure in which a high melting point resin is arranged in a core component and a low melting point resin having a melting point lower by 15 ° C. or more than the melting point of the high melting point resin is arranged in a sheath component. The method for producing a molded product of a fiber assembly according to the above item (5) or (6), which is a thermoplastic composite short fiber.
(8) The method for producing a molded product of a fiber assembly according to (7), wherein the heat treatment is performed at a temperature that is equal to or higher than the melting point of the low melting point resin of the thermoplastic composite short fiber and equal to or lower than the melting point of the high melting point resin.
(9) The method for producing a fiber assembly molded product according to any one of (5) to (8), wherein the thermoplastic composite short fiber assembly is processed into a spherical shape.
[0007]
Hereinafter, the present invention will be described in detail. The fiber polymer molded product referred to in the present invention means that a single fiber fineness of 10 to 100 denier and a fiber length of 38 to 105 mm of crimped thermoplastic fibers are dispersed and entangled in a three-dimensional direction so that short fibers are joined together. It has a structure in which dots are fusion-bonded. The inside of the fiber assembly molded product has a fine porous structure that maintains a high porosity of 90 to 98%, preferably 95 to 98%, due to the dispersion and entanglement of the fibers in which crimps are expressed. This fine porous structure captures suspended matter (hereinafter abbreviated as SS) in sewage, helps infiltration and implantation of aerobic microorganisms that promote self-purification of sewage, and promotes its growth action. Is suitable. If the porosity is less than 90%, the fibers become overly dense and adversely affect the capture of SS and the implantation of aerobic microorganisms, and the purification action is reduced. In addition, since the SS once captured from the fiber assembly molded product during backwashing is not easily removed, the frequency of use increases and the filtration efficiency greatly decreases. On the other hand, if the porosity exceeds 98%, the fiber assembly molded product becomes rough, and the filtration efficiency is inferior.
[0008]
The thermoplastic conjugate fiber used for the fiber assembly molded product of the present invention is composed of a low melting point resin and a high melting point resin having a melting point difference of 15 ° C. or more. Examples of the high melting point resin include polyester, polyamide, polyphenylene sulfide, and polypropylene, and examples of the low melting point component include polypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, α-olefin copolymer, low Examples include a melting point polyester (isophthalic acid copolymer polyester), and the combination is not particularly limited as long as the difference in melting point is 15 ° C. or more, and can be arbitrarily selected within a range that does not hinder the intended effect. If the difference in melting point is less than 15 ° C., thermal bonding is likely to be insufficient due to management difficulties during bonding processing, and as a result, short fibers are washed away during filtration and backwashing.
As the structure of the thermoplastic conjugate fiber, a sheath core type structure having the low melting point resin as a sheath component and a high melting point resin as a core component, and a so-called sheath core concentric structure in which the positions of the core components in the fiber cross section are concentric, A so-called sheath-core eccentric structure in which the position of the core component in the fiber cross section is eccentric, or a sea-island structure in which a plurality of core components are arranged, or a parallel structure of a low-melting resin and a high-melting resin is used. A sheath-core structure in which the high melting point resin is entirely covered with a low melting point resin is also preferable in order to more effectively perform the fusion bonding of the joining points of the intertwined short fibers.
In the composite fiber, the composite ratio of the low melting point resin and the high melting point resin is 10/90 to 90/10 (weight ratio), more preferably 30/70 to 70/30 (weight ratio). When the low melting point resin is less than 10% by weight, the fusion bonding at the joining point between the short fibers becomes insufficient, and the shape retention of the fiber aggregate molded product is lowered. On the other hand, if it exceeds 90% by weight, it becomes difficult to form a porous structure.
[0009]
The average specific gravity of the thermoplastic conjugate fiber used in the present invention is not particularly limited, but is preferably 1.0 to 1.5 g / cm ³ , more preferably 1.1 to 1.4 g / cm ³ . When the fiber assembly molded product of the present invention is used as a filter medium, if the average specific gravity of the thermoplastic conjugate fiber constituting the molded product is less than 1.0 g / cm ^{3, the} fiber is floated during filtration and the filtration efficiency is lowered. On the other hand, if the average specific gravity exceeds 1.5 g / cm ³ , it is not preferable because of an increase in aeration load during backwashing and workability during replacement. Incidentally, talc in an amount not to adversely affect the present invention in order to adjust the specific gravity to the thermoplastic composite fibers, calcium carbonate, may contain inorganic filler such as mica.
[0010]
The thermoplastic conjugate fiber used in the present invention has a single yarn fineness of 10 to 100 denier, preferably 20 to 60 denier, more preferably 25 to 50 denier. The fiber length is 38 to 105 mm, preferably 45 to 78 mm. When the single yarn fineness is less than 10 denier, the shape retention is slightly inferior. For example, when used as a filter medium, the removal of SS at the time of backwashing becomes insufficient and the filtration efficiency becomes inferior. On the other hand, if it exceeds 100 denier, the intertwined space becomes too large and the filtration efficiency becomes inferior. On the other hand, if the fiber length is less than 38 mm, it is difficult to produce a sliver in which short fibers are converged, and if the fiber length exceeds 105 mm, the fiber assembly molded product becomes dense, resulting in poor filtration efficiency. Crimping has an important meaning for the fiber assembly molded product of the present invention. That is, the short fibers in the fiber lump are dispersed and entangled in the three-dimensional direction, but the entanglement between the fibers is promoted by having the crimps, and a complicated network-like three-dimensional structure is entangled. Among the sheath-core structures, in particular, in the case of the sheath-core eccentric structure, latent crimps due to a difference in shrinkage between the low melting point resin and the high melting point resin can be expressed and entangled. Furthermore, both the manifestation of this latent crimp and the actual crimp due to the mechanical crimp can be utilized. In the latter case in particular, a more complicated three-dimensional crimp, in which both spiral crimps due to latent crimps and zigzag crimps due to mechanical crimps, are mixed, so the porous structure formed in the fiber mass is also It becomes a fiber mass of a complex three-dimensional deep network porous structure. When a fiber aggregate molded product composed of such a fiber mass is used as a purification treatment material or the like, it promotes the trapping of the suspended substances described above, facilitates the entry of aerobic microorganisms, and further increases the number of implantation sites. Becomes active and the purification action is improved. The number of crimps is within a range in which a sliver can be produced in consideration of the card passing property, and is preferably 5 to 20 peaks / 25 mm, particularly preferably 8 to 16 peaks / 25 mm. As a method for imparting crimps, a known method such as a stuffing box method or a gear-type crimper can be used, and the crimped form is not particularly limited, such as spiral form or zigzag form.
[0011]
The fiber assembly molded product of the present invention comprises a fiber mass having such a porous structure, and the fiber mass molded product obtained as a result of the joint points of the intertwined fibers being fused and joined in the fiber mass. In the inner and outer layers, the short fibers are almost uniformly dispersed and entangled, the porosity is 90 to 98%, and a porous structure retaining fine voids is obtained.
Since the fiber assembly molded product of the present invention has such a porous structure, the shape retention rate is extremely high with respect to external pressure. Especially when the fiber assembly molded product of the present invention is used as a filter medium, On the other hand, since the shape retention rate is extremely high, the above-described aerobic microorganisms can be kept in the entrance and implantation, and the constant proliferation action can be promoted over a long period of time. In addition, it is possible to remove suspended substances collected while maintaining the shape with almost no deformation during backwashing, which greatly contributes to recycling. Although the high shape retention ratio greatly depends on the rigidity of the composite short fiber, even when used as a filter medium, the rigidity that can withstand water external pressure resistance such as continuous stirring varies depending on the fiber, but the fineness is 10 to 100. Denier is suitable.
[0012]
In producing the fiber assembly molded product of the present invention, the production method is not particularly limited, but for example, it can be produced by the following method. After applying a predetermined number of mechanical crimps to the tow of a thermoplastic composite fiber having a single yarn fineness of 10 to 100 denier with a stuffing box or the like, an appropriate amount of the web opened by cutting to a fiber length of 38 to 105 mm is collected. However, a preferred embodiment of the fiber lump is to form the sliver by converging the spread web and then cutting the sliver into a predetermined length with a cutting machine. After forming a plastic composite short fiber aggregate, it is processed into a spherical fiber mass by contact rotational movement from above and below and / or from left and right.
The spherical fiber mass processed in this way becomes a porous structure having a fine void inside the fiber mass and a porosity of 90 to 98%. According to this method, it is possible to more efficiently obtain a fiber aggregate molded product having a high porosity suitable for the growth of aerobic microorganisms.
Next, the fiber mass is heat-treated at a temperature at which one component of the composite short fibers constituting the fiber mass softens or melts. With respect to the fiber mass that has become spherical, it is particularly preferable that the heat treatment is performed by blowing hot air onto the spherical fiber mass from below using a heat treatment device such as a hot air dryer or a hot air circulating furnace within the above temperature range. In this state, the splices of the short fibers are fused and joined while floating the spherical fiber mass on a moving belt such as a wire net by adjusting the hot air pressure. The heat treatment can be adjusted by the balance between heat treatment time and temperature. In particular, the heat treatment performed while the fiber mass is suspended, which is optimal for obtaining a spherical fiber mass, does not cause fusion bonding between adjacent fiber masses, and maintains the spherical shape before supply while maintaining the inside of the fiber mass. As a result of the fact that the fiber joints of the composite short fibers can be heat-sealed, the resulting fiber aggregate molded product has a three-dimensional network structure in which the short fibers are very homogeneously dispersed and intertwined in the outer and inner layers of the molded product. It is preferable at the point which produces. By this three-dimensional network structure, the porosity is high and, for example, it can have a high shape retention rate with almost no deformation even with an external pressure such as a water flow. And according to this method, the fiber aggregate molded product having a porosity of 90 to 98% can be obtained more efficiently. When the fiber assembly molded product having a porous structure obtained by such a production method is used as, for example, a water treatment material, it has an excellent effect that the fiber does not fall off or flow out even when used or backwashed. It plays.
The shape retention with respect to the external pressure can be expressed by various methods. In the present invention, the fiber assembly is molded to a height of 60 cm in a filter having a perforated plate at the bottom, a height of 200 cm, and an inner diameter of 50 cm. After filling the product, the height (H1) of the molded product of the fiber assembly when the raw water is filled in the filter is measured, and the fiber assembly is passed through the raw water for 24 hours at a filtration speed of 60 m / h. The height (H2) of the body molded product was measured, and from these measured values, the value obtained by the following equation was defined as “shape retention ratio” as an index of shape retention with respect to external pressure.
Shape retention rate (%) = (H2 / H1) × 100
When the shape retention rate is 85% or more, the fiber assembly molded product of the present invention preferably has a resistance to external pressure. For example, when it is used as a filter medium, it is clogged with the frequency of use and has a high filtration efficiency. Compared with the conventional filter material which brings about the fall, since the magnitude | size of a space | gap is maintained, the outstanding performance which can maintain favorable filtration efficiency for a long term is exhibited.
The size of the fiber assembly molded product of the present invention is arbitrarily selected for various uses and purposes and is not particularly limited. Even when a spherical fiber assembly molded product is used as a filter medium, the size thereof can be arbitrarily selected, and for example, one having an average diameter of 20 to 30 mm can be selected.
[0013]
【Example】
EXAMPLES Next, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples. In addition, the measuring method used for each Example is shown below.
[Porosity]
Specific gravity S ₁ of the apparent fiber aggregate molding (g / cm ³⁾ and specific gravity of the composite short fibers constituting the molded article _{^{S 2 (g / cm 3)}} , it was determined by the following equation.
Porosity (%) = (S ₂ −S ₁ ) × 100 / S ₂
[SS residual ratio]
The weight W ₁ (g / 50 pieces) of the fiber lump before filtration and the weight W ₂ (g / 50 pieces) after drying of the fiber lump after backwashing were measured, and the residual rate of SS was determined.
SS residual rate (%) = (W ₂ −W ₁ ) × 100 / W ₁
[Degree of shedding of short fibers]
Judgment was made based on the presence or absence of fibers that had been washed away after washing in the backwash.
[Shape retention]
Forming the fiber assembly when the filter assembly having a perforated plate at the bottom, having a height of 200 cm and an inner diameter of 50 cm is filled with the fiber assembly molded product up to a height of 60 cm, and then the raw water is filled in the filter Measure the height (H1) of the product, measure the height (H2) of the fiber assembly molded product after passing raw water through the filtration rate of 60 m / h for 24 hours, and obtain the shape retention by the following formula It was. From the shape retention rate, the shape retention performance was evaluated according to the following criteria.
Shape retention rate (%) = (H2 / H1) × 100
Criteria ○: 90% or more Δ: 80% or more and less than 90% ×: less than 80% (Example 1)
High-density polyethylene having a melting point of 126 ° C. as a sheath component, polyester having a melting point of 256 ° C. as a core component, a sheath-core composite ratio of 60/40 (weight ratio), a single yarn fineness of 32 denier, and a zigzag crimp of 10 threads / 25 mm. The sheath core concentric composite short fiber having a fiber length of 50 mm was passed through a card machine, and the obtained web was converged to obtain a sliver having a total fineness of 80,000 denier. This sliver is cut into 28 mm and rounded into a ball shape, then transferred to a wire mesh conveyor type hot air circulation dryer adjusted to 140 ° C., and hot air of 140 ° C. is blown from below the wire mesh conveyor to float on the spherical fiber lump. While giving exercise, heat treatment was performed for 20 seconds. The obtained fiber aggregate molded product had a porous structure with an average diameter of 25 mm, a porosity of 97%, and an average specific gravity of the composite short fibers constituting the molded product of 1.2 g / cm ³ . . This molded product has a perforated plate at the bottom, is filled up to a height of 60 cm in a filter having a height of 200 cm and an inner diameter of 50 cm, and the raw water treated with activated sludge is passed through the filter at the filtration rate of 60 m / hr for 24 hours. Then, raw water and treated water were collected at regular intervals, SS and BOD were measured, and the average value was obtained. In addition, after passing water for 24 hours, air was blown in from the lower part of the filter perforated plate, washing water was introduced and backwashing was performed for 1 hour, and as a result of examining the degree of fiber dropout in the backwash water, There was no dropout. In addition, the amount of SS remaining on the fiber assembly molded product after backwashing was hardly observed. The results are shown in Table 1.
[0014]
(Example 2)
High-density polyethylene having a melting point of 126 ° C. is used as a sheath component, polyester having a melting point of 256 ° C. is used as a core component, and the sheath-core composite ratio is 50/50 (weight ratio), the single yarn fineness is 60 denier, and 10 threads / 25 mm zigzag crimps. Except for using a sheath-core concentric composite short fiber having a fiber length of 38 mm, a spherical fiber assembly molded product having a porous structure (porosity 93%, the above-mentioned composition constituting the molded product) in the same manner as in Example 1. An average specific gravity of 1.2 g / cm ³ ) was obtained. The same filtration test as in Example 1 was performed using the obtained fiber assembly molded product as a water treatment medium. The results are shown in Table 1.
[0015]
Example 3
High-density polyethylene with a melting point of 126 ° C. as a sheath component, polyester with a melting point of 256 ° C. as a core component, sheath-core composite ratio 80/20 (weight ratio), single yarn fineness 25 denier, 14 threads / 25 mm zigzag crimp Except for using a sheath core concentric composite short fiber having a fiber length of 64 mm, a spherical fiber assembly molded product having a porous structure (porosity 98%, the above constituting the molded product) in the same manner as in Example 1. An average specific gravity of 1.1 g / cm ³ ) was obtained. The same filtration test as in Example 1 was performed using the obtained fiber assembly molded product as a water treatment medium. The results are shown in Table 1.
[0016]
Example 4
Zigzag cocoon with isophthalic acid copolymerized polyethylene terephthalate having a melting point of 200 ° C. as a sheath component, polyester having a melting point of 256 ° C. as a core component, sheath-core composite ratio 60/40 (weight ratio), single yarn fineness 10 denier, 10 threads / 25 mm A spherical fiber assembly molded article having a porous structure (same as in Example 1) except that a sheath-core concentric composite short fiber having a fiber length of 54 mm having shrinkage was heat-treated at 210 ° C. for 3 minutes with a hot air dryer ( A porosity of 96% and an average specific gravity of 1.4 g / cm ^{3 of the} composite short fiber constituting the molded product were obtained. The same filtration test as in Example 1 was performed using the obtained fiber assembly molded product as a water treatment medium. The results are shown in Table 1.
[0017]
(Example 5)
In Example 2, except that the composite short fiber was made into a sheath-core eccentric type, all the same as in Example 2, a spherical fiber assembly molded product having a porous structure (porosity 95%, constituting the molded product) An average specific gravity of 1.2 g / cm ³ ) of the composite short fiber was obtained. The crimp was 16 peaks / 25 mm, and a zigzag structure and a spiral structure were apparent. The same filtration test as in Example 1 was performed using the obtained fiber assembly molded product as a water treatment medium. The results are shown in Table 1.
[0018]
(Example 6)
In Example 3, a spherical structure having a porous structure was used in the same manner as in Example 3 except that a sheath core concentric composite short fiber having a fiber length of 72 mm having a single yarn fineness of 90 denier and 8 threads / 25 mm zigzag crimp was used. A fiber aggregate molded product (a porosity of 98%, an average specific gravity of 1.1 g / cm ^{3 of the} composite short fiber constituting the molded product) was obtained. The same filtration test as in Example 1 was performed using the obtained fiber assembly molded product as a water treatment medium. The results are shown in Table 1.
[0019]
(Comparative Example 1)
High-density polyethylene having a melting point of 126 ° C. is used as a sheath component, polyester having a melting point of 256 ° C. is used as a core component, and a sheath-core composite ratio is 60/40 (weight ratio), a single yarn fineness is 15 denier, and 10 threads / 25 mm zigzag crimps. Except for using a sheath-core concentric composite short fiber having a fiber length of 30 mm, in the same manner as in Example 1, an average diameter of 25 mm and a spherical shape corresponding to the fiber assembly molded product of the present invention (with a void ratio) 96%, the average specific gravity of the composite short fiber constituting the molded product was 1.2 g / cm ³ ). The same filtration test as in Example 1 was performed using a water treatment medium corresponding to the fiber assembly molded product. The results are shown in Table 1.
[0020]
(Comparative Example 2)
The sliver with a total fineness of 80,000 denier obtained in Example 1 was cut into 60 mm and was rolled into a ball shape in the same manner as in Example 1 except that the average diameter was 20 mm and it was spherical. A product corresponding to a fiber aggregate molded product (porosity 80%, average specific gravity of the composite short fiber constituting the molded product 1.2 g / cm ³ ) was obtained. The same filtration test as in Example 1 was performed using a water treatment medium corresponding to the fiber assembly molded product. The results are shown in Table 1.
[0021]
(Comparative Example 3)
Except for the single yarn fineness of 110 denier, the same as in Example 1, the average diameter is 30 mm, which corresponds to the spherical fiber assembly molded product of the present invention (porosity 90%, constituting the molded product) An average specific gravity of 1.2 g / cm ³ ) of the composite short fiber was obtained. The same filtration test as in Example 1 was performed using a water treatment medium corresponding to the fiber assembly molded product. The results are shown in Table 1.
[0022]
(Comparative Example 4)
Polypropylene short fiber with a single yarn fineness of 10 denier and a fiber length of 38 mm (melting point 160 ° C.) and polyethylene with a single yarn fineness of 10 denier and a fiber length of 38 mm (melting point 126 ° C.) are blended at a weight ratio of 50/50 into a card machine. The obtained web was converged to obtain a sliver with a total fineness of 70,000 denier. Hereinafter, similar to Example 1, equivalent to a spherical fiber assembly molded product of the present invention (porosity 97%, average specific gravity of the short fibers constituting the molded product 0.94 g / cm ³ ) Got. The same filtration test as in Example 1 was performed for the fiber assembly molded product. The results are shown in Table 1.
[0023]
(Comparative Example 5)
In Comparative Example 1, the fiber assembly of the present invention was used in the same manner as in Comparative Example 1 except that a sheath core concentric composite short fiber having a fiber length of 38 mm and a zigzag crimp of 18 threads / 25 mm was used. A product corresponding to a body molded product (void ratio 97%, average specific gravity of the composite short fiber constituting the molded product 1.2 g / cm ³ ) was obtained. The same filtration test as in Example 1 was performed for the fiber assembly molded product. The results are shown in Table 1.
[0024]
(Comparative Example 6)
Except having been heat-treated with a hot air dryer at 125 ° C., a fiber assembly molded product of the present invention (porosity 97%) was obtained in the same manner as in Example 1. The same filtration test as that of Example 1 was performed for the fiber aggregate molded product. However, the short fibers were separated at the time of filtration due to poor fusion-bonding at the joints between the fibers.
[0025]
[Table 1]

[0026]
【The invention's effect】
The fiber bundle molded product of the present invention, particularly when used as a water treatment filter medium, has a large shape retention even during long-term use, no fiber loss, high suspended matter filtration efficiency, and backwashing Sometimes, the removal rate of the collected suspended substance is high, the filtration effect is excellent, and it can be easily manufactured at low cost.

Claims

The thermoplastic composite comprising a fiber lump in which thermoplastic short fibers having a single yarn fineness of 10 to 100 denier, a fiber length of 38 to 105 mm and having crimps are assembled, and constituting the fiber lump. A fiber assembly molded product in which short fibers are dispersed and entangled in a three-dimensional direction, and the joining points of the short fibers are fusion-bonded, and the porosity is 90 to 98%, and the shape is maintained against external pressure. A fiber assembly molded product characterized in that the rate is 85% or more.

The fiber assembly molded product according to claim 1, wherein the thermoplastic composite short fiber is a thermoplastic composite short fiber having a single yarn fineness of 20 to 60 denier and a fiber length of 45 to 78 mm.

The fiber assembly molded product according to claim 1 or 2, wherein the thermoplastic composite short fibers are thermoplastic composite short fibers having an average specific gravity of 1.0 to 1.5 g / cm ³ .

Thermoplastic composite having a sheath-core structure in which a thermoplastic composite short fiber has a high melting point resin disposed in the core component and a low melting point resin having a melting point lower by 15 ° C. or more than the melting point of the high melting point resin disposed in the sheath component The fiber assembly molded product according to any one of claims 1 to 3, which is a short fiber.

A thermoplastic composite short fiber aggregate having a single yarn fineness of 10 to 100 denier, a fiber length of 38 to 105 mm, and having crimps is heat-treated after being processed into a fiber mass having a porosity of 90 to 98%. The method for producing a molded product of fiber assembly according to claim 1 .

6. The method of producing a fiber assembly molded product according to claim 5, wherein the thermoplastic composite short fiber assembly is obtained by cutting a sliver in which thermoplastic composite fibers are gathered into a predetermined length.

Thermoplastic composite having a sheath-core structure in which a thermoplastic composite short fiber has a high melting point resin disposed in the core component and a low melting point resin having a melting point lower by 15 ° C. or more than the melting point of the high melting point resin disposed in the sheath component The method for producing a fiber assembly molded product according to claim 5 or 6, wherein the fiber assembly is a short fiber.

The method for producing a molded product of a fiber assembly according to claim 7, wherein the heat treatment is performed at a temperature not lower than the melting point of the low melting point resin of the thermoplastic composite short fiber and not higher than the melting point of the high melting point resin.

The process for producing a fiber assembly molded product according to any one of claims 5 to 8, wherein the thermoplastic composite short fiber assembly is processed into a spherical shape.