JP3861520B2

JP3861520B2 - Cylindrical filter

Info

Publication number: JP3861520B2
Application number: JP20712399A
Authority: JP
Inventors: 重則福田; 修山口
Original assignee: Chisso Corp
Current assignee: JNC Corp
Priority date: 1999-07-22
Filing date: 1999-07-22
Publication date: 2006-12-20
Anticipated expiration: 2019-07-22
Also published as: JP2001029717A

Description

【０００１】
【発明の属する技術分野】
本発明は、液体濾過用の筒状フィルターに関する。詳しくは、熱可塑性繊維を含有しその繊維交点の少なくとも一部が接着され、切り込みなどの方法によって舌片部が設けられた帯状不織布を、有孔円筒体に綾状に巻き付けてなる、通液性、濾過ライフ、濾過精度等の濾過性能が良好な筒状フィルターに関する。
【０００２】
【従来の技術】
現在、さまざまな産業分野で流体中の異物等を濾過するために多様なフィルターが使用されている。中でも、フィルターの交換が容易であるカートリッジ型のフィルター（以下、筒状フィルターと記す）は、各種液体原料に含まれる異物の除去、メッキ液やエッチング液に発生する懸濁粒子の除去、塗料中に発生する凝集物の除去、工業用水やプール水の浄化などの幅広い分野で使用されている。筒状フィルターの中では糸巻き型筒状フィルターがよく知られており、これは有孔円筒状のコアに濾材となる紡績糸を綾状に巻き付けることで作られている。糸巻き型筒状フィルターでは、濾過精度のグレードを揃える際に紡績糸を巻き付けるコアの回転数に対する綾振りの速度を変更し、紡績糸同士の間隔を調節することで、糸巻き形状を変えてフィルターの濾過精度を調節している。このため多種の紡績糸を用意する必要がなく、製造が容易で安価なため、古くから利用されており、現在でも非常に多くの数が使用されている。
【０００３】
しかしながら、この糸巻き型筒状フィルターにはいくつかの欠点がある。例えば、フィルターの粒子捕集方法は、紡績糸自身の開孔部で粒子を捕集する他、紡績糸から発生する毛羽や紡績糸同士の間隙でも粒子を捕集するものであるが、毛羽の発生量や紡績糸同士の間隙にばらつきが生じ易いため、製品の濾過精度のばらつきが大きく、紡績糸の細かな濾過精度分けが難しいという欠点がある。また、紡績糸に使用される繊維の細さに限界があるため、濾過精度の高精度化が難しく、更に、紡績糸同士の間隔を広げすぎると粒子の捕集が充分にできなくなるため、濾過精度を粗くする方向にも限度がある。この結果、紡績糸による糸巻き型筒状フィルターでは製造できる濾過精度の範囲に限界が生じてしまう。更には、紡績糸は短繊維を撚って作られるため、液体を濾過した際、紡績糸から繊維が脱落し、濾液に混入するという欠点もある。
【０００４】
このような従来の糸巻き型筒状フィルターの問題点を解決するための方法として、例えば実公平６−７７６７号公報には、多孔性を有するテープ状の紙や不織布に撚りを加えながら、テーパ状のコーンを通すことで押し潰して絞り込み、その直径を３ｍｍ程度に規制した濾過素材を、多孔性内筒に密接綾で巻回した形の糸巻き型筒状フィルターが提案されている。また、巻回の巻きピッチを多孔性内筒より外に向かうに従って大きくすることで大きな粒子を外側で捕集し、小さい粒子を濾過材中心部で捕集できるため濾過作用を長期に渡って得ることができるとしている。しかし、濾過素材を押し潰して絞り込んでいるために、濾過素材の空隙率が低くなり、濾過素材自身に取り込まれる粒子の捕集量は僅かになり、通液性も低下することになる。しかも密接綾巻きにより、濾過素材同士の間隙も僅かであるため、通液し易い空間が無く、フィルター自体の通液性が低下することになる。また、外側の巻ピッチを大きくすることで、大きな粒子を濾過素材同士の間隙で捕集するとあるが、粒子捕集に有効な間隙の部分は僅かであるため、間隙に勾配を持たせても粒子捕集量は増えず、表面閉塞され易く、濾過ライフは非常に短くなってしまう。更に、濾過精度の粗いフィルターを作るために、同じ濾過素材で間隔を開けて巻くと、濾過素材には紡績糸のような毛羽がないため、濾過素材同士の間隙から粒子が流出するため、本来、粗い粒子程、捕集効率が上がるはずが、ある粒径で捕集効率の低いまま頭打ちになったり、粗い粒子の捕集効率が低下してくる結果になる。このため、濾過精度の異なるフィルターを作るためには、濾過精度毎に繊維径や空隙率の異なるテープ状の紙や不織布を用意しなければならず、生産性の低下や原料費の増加を招いてしまう。
【０００５】
別の方法として、特開平４−４５８１０号公報には、構成繊維の１０重量％以上が０．５デニール以下に分割されている複合繊維からなるスリット不織布を、多孔性芯筒上に繊維密度が０．１８〜０．３０ｇ／ｃｍ³となるように巻き付けたワインドフィルターが提案されている。この方法を利用すると、繊度の小さい繊維によって液体中の細かな粒子を捕捉できるという特長がある。しかしながら、複合繊維を分割させるためは高圧水流などの物理的応力を加える必要があり、不織布全体を均一に分割させることが難しく、均一に分割されず、太い繊維が残っていると不織布中に捕集効率の悪い部分が生じるため、フィルター全体として濾過精度が低下してしまう。また、分割繊維の紡糸と分割に要する生産コストが通常の紡績糸より増加することにより、フィルターの価格が高くなり、従来、糸巻き型筒状フィルターが使われていた、安価であることが求められる分野には適さなくなってしまう。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、上記課題が解決された、通液性、濾過ライフ、濾過精度等の濾過性能が良好な、糸巻き型の筒状フィルターを提供することにある。
【０００７】
【課題を解決するための手段】
本発明者等は、鋭意検討の結果、熱可塑性繊維を含有し、その繊維交点の少なくとも一部が接着され、舌片部となる切り込みが設けられた帯状不織布を有孔円筒体に綾状に巻き付けてなる筒状フィルターが、上記課題を解決することを見出し本発明を完成した。
本発明は下記の構成を有する。
（１）熱可塑性繊維を含有し、その繊維交点の少なくとも一部が接着された、舌片部を有する帯状不織布を、有孔筒状体に綾状に巻き付けてなる筒状フィルター。
（２）舌片部を有する帯状不織布が、熱可塑性繊維を少なくとも３０重量％含有する不織布である前記（１）項記載の筒状フィルター。
（３）舌片部を有する帯状不織布が、熱エンボスロールで熱圧着されている前記（１）または（２）項記載の筒状フィルター。
（４）舌片部を有する帯状不織布の繊維交点の少なくとも一部が、熱接着されている前記（１）〜（３）項のいずれか１項記載の筒状フィルター。
（５）舌片部を有する帯状不織布の全面積に対する舌片部の面積率が、１０〜８０％である前記（１）〜（４）項のいずれか１項記載の筒状フィルター。
（６）舌片部を有する帯状不織布に撚りが加えられた前記（１）〜（５）項のいずれか１項記載の筒状フィルター。
（７）筒状フィルターの濾過層の空隙率が６５〜９０％である前記（１）〜（６）項のいずれか１項記載の筒状フィルター。
（８）舌片部を有する帯状不織布が長繊維からなる不織布である前記（１）〜（７）項のいずれか１項記載の筒状フィルター。
（９）舌片部を有する帯状不織布を構成する熱可塑性繊維が低融点樹脂と高融点樹脂からなり、それら両樹脂の融点差が１０℃以上の複合繊維である前記（１）〜（８）項のいずれか１項記載の筒状フィルター。
（１０）筒状フィルターの濾過層の一部に舌片部を有する帯状不織布以外の多孔性材料が用いられた前記（１）〜（９）のいずれか１項記載の筒状フィルター。
【０００８】
【発明の実施の形態】
以下、本発明を具体的に説明する。
本発明の筒状フィルターは、熱可塑性繊維を含有し、その繊維交点の少なくとも一部が接着され、かつ、図２、図３に示すような舌片部を有する帯状不織布が集束された後、図１に示すような有孔筒状体６に綾状に巻回されてなる筒状フィルター５である。筒状フィルターの濾過層の素材として、舌片部を有する帯状不織布を用いることで、帯状不織布の集束物で形成される間隙に舌片部が存在するため、従来は間隙を通過して捕集できなかった粒子が舌片部に捕集され、捕集効率が向上し、更に、舌片部の凹凸による粒子捕集面積の増加により、粒子の捕集量が多くなることによって、筒状フィルターの濾過精度、濾過ライフ等が優れたものとなる。
【０００９】
本発明の筒状フィルターの素材としては、熱可塑性繊維を含有し、その繊維交点の少なくとも一部が接着された、舌片部を有する帯状不織布（以下、舌片部含有帯状不織布という）が用いられる。
前記舌片部含有帯状不織布は、未処理不織布（以下、原反不織布という）をスリット等により所望の幅にした後、加圧された刃付きロールとゴムロールの間に通して切り込みを入れる方法等で得られる。スリット等は原反不織布に切り込みを入れた後に行っても構わない。
尚、以下の説明において単に不織布という場合は、前記舌片部含有帯状不織布と原反不織布の総称を意味する。
【００１０】
前記熱可塑性繊維の原料には、溶融紡糸が可能な熱可塑性樹脂を使用することができる。その例として、ポリプロピレン、低密度ポリエチレン、高密度ポリエチレン、線状低密度ポリエチレン、プロピレンとエチレンの共重合体、プロピレン／エチレン／ブテン−１共重合体、プロピレンと他のα−オレフインとの二〜三元共重合体等をはじめとするチグラーナッタ触媒やメタロセン触媒を用いて重合されたポリオレフィン系樹脂、ポリエチレンテレフタレ−ト、ポリブチレンテレフタレ−ト、酸成分をテレフタル酸以外にイソフタル酸を併用して共重合した低融点ポリエステル、ナイロン−６、ナイロン−６６などのポリアミド系樹脂、ポリスチレン、シンジオタクチツクポリスチレンなどのポリスチレン系樹脂、ポリウレタンエラストマ−、ポリエステルエラストマ−、乳酸系ポリエステル等の生分解性樹脂等を挙げることができ、これら熱可塑性樹脂は単独で使用しても、二種以上を混合して使用してもよい。
また、前記熱可塑性繊維を用いて原反不織布を形成する際には、前記熱可塑性繊維を単独もしくは二種類以上を混ぜて用いることが出来る。
【００１１】
前記熱可塑性繊維は、融点差が１０℃以上好ましくは１５℃以上ある低融点樹脂と高融点樹脂からなる熱可塑性複合繊維であると熱処理等により、原反不織布の繊維接合点の熱接着を確実に行なうことが出来る。融点差の上限は特にないが、溶融紡糸可能な熱可塑性樹脂の内、最高融点の樹脂と最低融点の樹脂との温度差が該当する。なお、明確な融点が存在しない樹脂の場合には流動開始温度を融点と見なす。複合繊維の形態としては、並列型や鞘芯型等、低融点樹脂が繊維表面の少なくとも一部に存在する形態であればよい。
【００１２】
複合繊維の低融点樹脂と高融点樹脂の組合せは、融点差が１０℃以上好ましくは１５℃以上あれば特に限定されない。例えば、線状低密度ポリエチレレン／ポリプロピレン、高密度ポリエチレン／ポリプロピレン、低密度ポリエチレン／ポリプロピレン、プロピレンと他のα−オレフインとの共重合体／ポリプロピレン、線状低密度ポリエチレン／高密度ポリエチレン、低密度ポリエチレン／高密度ポリエチレン、線状低密度ポリエチレン／ポリエチレンテレフタレ−ト、ポリプロピレン／ポリエチレンテレフタレ−ト、エチレングリコ−ルと酸成分としてテレフタル酸とイソフタル酸を共重合した低融点ポリエステル／ポリエチレンテレフタレ−ト、ナイロン６／ナイロン６６等が例示できる。特に耐薬品性に優れるポリオレフイン系樹脂／ポリオレフイン系樹脂、ポリオレフイン系樹脂／ポリエチレンテレフタレ−ト等が好ましく用いられる。また、複合繊維のいずれかの成分または両方の成分に二種以上の混合樹脂を用いてもかまわない。
【００１３】
本発明で用いられる不織布には熱可塑性繊維が少なくとも３０重量％含まれている方が好ましい。勿論この熱可塑性繊維が１００重量％であってもよい。熱可塑性繊維を含むことで後記の繊維同士の熱接着が可能となり、各種バインダーで繊維を接合した場合に比べ、通水性、耐薬品性、濾材脱落防止等の性能が向上する。不織布に含まれている熱可塑性繊維が３０重量％未満であると熱圧着処理やスル−エア熱処理等で熱接着した際の繊維接着点の強力や数が充分でないため、濾過時に繊維が脱落し易くなり濾液に混入する恐れが出てくる。また、前記不織布には７０重量％以下の範囲で熱可塑性繊維以外の繊維を用いることができる。前記熱可塑性繊維以外の繊維としては、レ−ヨン、キュプラ、綿、麻、パルプ、炭素繊維、金属繊維等が例示できる。
【００１４】
前記不織布の形成に用いられる繊維の単糸繊度は、筒状フィルターの用途や要求される濾過性能によって異なるが、０．０１〜５００ｄｔｅｘが好適である。前記繊維によつて形成される不織布としては、長繊維不織布、短繊維不織布、長繊維と短繊維不織布が混合された不織布、これら、不織布を組み合わせた積層不織布等が例示でき、何れも本発明の筒状フィルターの素材に使用可能である。
製法別による不織布の種類としては、スパンボンド法不織布、メルトブロー法不織布、トウ開繊法不織布、エアレイド法不織布、カード法不織布、高圧水絡合不織布等が例示でき、何れも本発明の筒状フィルターの素材に使用可能である。特に、スパンボンド法不織布やメルトブロー法不織布は、濾液の泡立ちの原因となる繊維仕上げ剤を含まないため、これを嫌う濾過用途には有効である。更に、これら不織布は、活性炭、イオン交換樹脂、殺菌剤等をバインダーや熱接着法、樹脂練り込み法等で含有していてもよい。
【００１５】
前記不織布の繊維交点の接着は、熱エンボスロール、熱フラットカレンダーロール、超音波エンボスのような装置を使用し、熱圧着したものや、熱風貫流型、上下方向熱風噴流型、赤外線ヒーター型等の熱処理機を使用し、熱接着したもの等が例示できる。また、前記不織布が熱エンボスロール圧着不織布の場合、不織布部分の全面積に対するエンボス熱圧着面積の割合である熱圧着面積率は５〜３０％、より好ましくは５〜２５％とすることが望ましい。熱圧着面積率が５％を下回ると、繊維交点の接着部分が少ないために繊維の脱落が多くなったり、不織布強度が低下し、筒状フィルターを製造する際、舌片部含有帯状不織布が切断し易く、均一な濾過性能を有するものが得られない。また、熱圧着面積率が３０％を越えると、筒状フィルターの通液性や濾過ライフが低下する。
【００１６】
前記原反不織布の空隙率は、６０〜９５％、より好ましくは６５〜９２％である。空隙率６０〜９５％の原反不織布から得られる舌片部含有帯状不織布を用いた場合、筒状フィルターの濾過層は必要以上に密になることが抑えられ、フィルターとして使用したときの圧力損失が十分に抑えられ、粒子捕集効率をより向上させることができる。また、前記原反不織布の空隙率を９５％以下とすることにより、舌片部含有帯状不織布の有効筒状体への巻回が容易となり、得られる筒状フィルターの負荷圧力による変形をより小さくすることができる。
【００１７】
前記舌片部含有帯状不織布としては、広幅の原反不織布を帯状にスリットしたものが好ましく用いられる。スリットされた帯状不織布の幅は、０．５〜２０ｃｍが好ましく、更に好ましくは１〜１０ｃｍである。この幅が０．５ｃｍ未満であると有孔筒状体に綾状に巻回する時に舌片部含有帯状不織布が切断する恐れがあり、また、張力の調節が困難である。また、２０ｃｍを越えると、舌片部含有帯状不織布を集束させ有孔筒状体に綾状に巻回する時に、舌片部が集束した不織布内部へ封入され易くなり、舌片部の効果が十分に発揮されなくなる。なお、不織布の目付は、１０〜２００ｇ／ｍ²が好ましい。この値が１０ｇ／ｍ²よりも小さくなると、繊維量が少なくなるために、不織布のむらが大きくなったり、あるいは不織布の強度が低下してフィルターへの加工が難しくなる。一方、この値が２００ｇ／ｍ²よりも大きくなると、不織布が厚くなるため、舌片部の形成が困難になる。
【００１８】
次に、舌片部について説明する。舌片部は帯状不織布の一部に切れ込みを入れるたり、不織布の一部を除去することで形成される。舌片部の例としては、図２（Ａ）（Ｂ）（Ｃ）のように帯状不織布のエッジ４から舌片部３となる切れ込み２を入れた形状や、図３（Ａ）（Ｂ）（Ｃ）のように帯状不織布の面内に舌片部３となる形状の切れ込み２を入れた形状が示される。帯状不織布に形成される舌片部３の長さや大きさは、全て同じでなくてもよく、切れ込み２の方向、形状、形状の向き等についても異なったものが混在したり、図２と図３の形状を組み合わせたものでも構わない。また、帯状不織布１における舌片部３の位置が長さ方向に対して左右対称でなくてもよく、更に、片側にだけ配置させてもよい。ただし、舌片部含有帯状不織布１が先に有孔筒状体に巻かれる方向を上流、逆方向を下流とした場合、図２のような形状については、上流側から下流側に向けて切れ込みが入る形状、図３の形状については、帯状不織布と繋がる部分が下流側にある方が、有孔筒状体に巻き付ける際、ワインダーのガイドを通って帯状不織布が絞り込まれたときに舌片部３が立ち易く、舌片部３による効果がより顕著に現れるため望ましい。
【００１９】
帯状不織布に舌片部を形成する方法例としては、舌片部となる切れ込みを入れるための刃を持つプレス用金型を用い、この金型をセットしたテープ用連続プレス機に帯状不織布を通す方法、片側に舌片部となる切れ込みを入れるための刃を持つロールとフラットロールとで加圧された間に帯状不織布を通す方法、高圧水流による切断する方法や加熱された刃を押しつけたり、レーザー光線により溶融除去する方法等が挙げられる。なお、原反不織布に舌片部を加工した後、スリットして舌片部含有帯状不織布としてもよい。
【００２０】
前記舌片部の全面積は、舌片部含有帯状不織布の全面積に対して１０〜８０％である。なお、不織布が除去されている場合は、その部分の面積は計算に含まない。舌片部の面積率が１０％未満であると舌片部による濾過精度や濾過ライフの向上が現れず、８０％を越えると、舌片部含有帯状不織布の強度が低下してしまい筒状フィルターへの加工が困難になる。なお、ここで言う舌片部の面積とは、図２のような形状については、図４（Ａ）または（Ｂ）に示すように帯状不織布のエッジ４と切れ込み２、及び、切れ込み２の両端部同士を結んだ線（破線で示す）で囲まれる斜線の部分、図３のような形状については、図５（Ａ）または（Ｂ）に示すように切れ込み２と切れ込み２の先端同士を結んだ線（破線で示す）で囲まれた斜線の部分が該当する。
【００２１】
前記舌片部含有帯状不織布を加撚後、有孔筒状体へ巻き付ける方法も好ましく用いられる。舌片部含有帯状不織布に撚りを加えると、舌片部含有帯状不織布に対して舌片部が立ち、その状態がしっかりと保持されるため、撚りを加えないときに比べて舌片部による効果が向上する。また、単位長さ当たりの撚りの数により、舌片部含有帯状不織布の空隙率を変化させることができるので、濾過精度を調整することができる。撚り数は、舌片部含有帯状不織布１ｍ当たり１５〜１５０回の範囲が好ましい。この値が１５回よりも小さくなると、撚りによる効果がほとんど得られない。また、この値が１５０回よりも多くなると、舌片部含有帯状不織布が強く絞られ繊維が詰まった状態になり、通水性や粒子捕集性が低下なるため好ましくない。
【００２２】
次に、筒状フィルターの製造方法について図６を用いて説明する。ワインダーのスピンドル９に有孔筒状体６を装着し、その端部にワインダーの糸道を通した舌片部含有帯状不織布１を巻き付けて固定する。スピンドル９のＣ方向への回転と共に、舌片部含有帯状不織布１は、トラバースガイド１０によってＢ、Ｂ’方向に綾状に振られて巻き付けられる。その時の巻き付け条件は、通常の糸巻き型フィルターの条件に準じて設定すればよく、例えばスピンドル回転速度５００〜１５００ｒｐｍにし、繰り出し速度を調節し、適当な張力をかけながら巻き付ければよい。巻き付け時の張力を調節して、筒状フィルターの内側の空隙率を密にし、中層、外層と徐々に張力を軽くして巻き付けることにより、濾過層の空隙率が変化した密度勾配型の筒状フィルターも得ることができる。この方法を用いると深層濾過による濾過ライフの向上が図れる。また、濾過精度はトラバースガイドの綾振り速度とスピンドルの回転速度の比率を調整して巻き付けパターンを変えることによっても変更することができる。そのパターンの付け方は、すでに公知である通常の糸巻き型筒状フィルターの方法を使用でき、ある糸（本発明では舌片部含有帯状不織布の集束物７）とその１つ下の層に巻かれた糸との糸間隔８が広い場合には濾過精度は粗くなり、逆に狭い場合には細かくなる。これらの方法により、舌片部含有帯状不織布を有孔筒状体の外径の１．５倍〜３倍程度の外径まで巻き付けて筒状フィルターに成形する。これをそのままフィルターとして用いてもよいし、端面に厚さ３ｍｍ程度の発泡ポリエチレンのガスケットを貼り付けるなどして、フィルター端面とハウジングとの密着性を上げるても良い。
【００２３】
本発明において有孔筒状体は、筒状フィルターの芯材の役目をするものであり、その材質や形状は濾過時の外圧に耐えられる強度を持ち、圧力損失が著しく高くなければ特に限定されるものではない。例えば、ポリプロピレン等の熱可塑性樹脂を格子状の開孔部をもつ筒状体に加工したもの、セラミックやステンレスを同様に加工したもの等でもよい。また、濾材がひだ折り加工されたプリーツ型フィルターや不織布巻回型フィルター等、外径が小さい他の種類のフィルターを使用してもよい。
【００２４】
本発明において、筒状フィルターの濾過層の空隙率は６５〜９０％の範囲であることが好ましい。この値が６５％よりも小さくなると、繊維密度が高くなりすぎるために通液性が低下してくる。前記空隙率が９０％よりも大きくなると濾過層の強度が弱くなり、濾過圧力が高い場合に濾過層が変形するなどの問題が生じてくる。前記空隙率を調節する方法として、舌片部含有帯状不織布の幅や舌片部の数や大きさ、舌片部含有帯状不織布の加撚量、舌片部含有帯状不織布を有孔筒状体へ巻回する時の張力等が挙げられる。
【００２５】
本発明においては、筒状フィルターの濾過層の一部に舌片部含有帯状不織布以外の多孔性材料を用いてもかまわない。その例としては、ポリエチレン／ポリプロピレン複合繊維不織布、メルトブロー法極細繊維不織布、ポリエチレン微多孔膜、ポリテトラフルオロエチレン微多孔膜、活性炭繊維や抗菌性繊維による不織布、イオン交換樹脂や活性炭等を担持させた不織布等が例示できる。このような舌片部含有帯状不織布以外の多孔性材料の使用により、濾過精度のコントロール、抗菌性や金属イオン吸着性等の機能付与等の効果が得られる。
【００２６】
【実施例】
以下実施例で本発明を更に詳細に説明する。なお、各例において不織布及び得られた筒状フィルターの濾過性能等の評価は以下に記載する方法で行った。
【００２７】
（原反不織布の目付）
原反不織布の面積が４００ｃｍ²となるように３箇所から帯状不織布を切り取り、重量を測定して、その平均値を１ｍ²当たりの重量に換算して目付（ｇ／ｍ²）とした。
【００２８】
（原反不織布の繊度）
原反不織布から無作為に５カ所サンプリングして、それらを走査型電子顕微鏡で撮影し、１カ所につき２０本の繊維を無作為に選んで、それらの繊維径を測定し、その平均値をその原反不織布の繊維径（μｍ）とした。また、繊度（ｄｔｅｘ）は繊維径と不織布原料の密度（ｇ／ｃｍ³）を使って次式から求めた。
なお、２種類以上の繊維が混綿等されている場合は、各々の繊維について前記の測定を行い、各繊維の繊度を計算した。
（繊度）＝π（繊維径）²×（密度）／４００
【００２９】
（舌片部含有帯状不織布の舌片部面積率）
舌片部含有帯状不織布から舌片部を含む面積が４００ｃｍ²となる長さの帯状不織布を切り取り、その舌片部の全面積（単位ｃｍ²）を測定し、次式から舌片部面積率（％）を計算した。
（舌片部面積率）＝｛（舌片部の全面積）／４００ｃｍ²｝×１００
【００３０】
（筒状フィルターの濾過層の糸間隔）
表層にある帯状不織布集束物（あるいは以下の実施例において有孔筒状体に巻き付けられた糸状物）と並行してその１つ下の層に巻かれた帯状不織布集束物との間隔（図１の８に示す）を１本の筒状フィルターにつき１０箇所測定し、その平均値を糸間隔（ｍｍ）とした。なお、舌片部として出ている部分は除いて測定した。
【００３１】
（筒状フィルターの濾過層の空隙率）
筒状フィルターの外径、内径、長さ、重量を測定し、次式を使って空隙率（％）を求めた。なお、濾過層そのものの空隙率を求めるため、内径の値には有孔筒状体外径を使用し、濾過層重量の値には筒状フィルターの重量から有孔筒状体の重量を引いた値を用いた。
（濾過層の見かけ体積）＝π｛（フィルターカートリッジ外径）²−（濾過層内径）²｝×（フィルターカートリッジ長さ）／４
（濾過層の真体積）＝（濾過層の重量）／（濾過層の原料の密度）
（濾過層の空隙率）＝｛１−（濾過層の真体積）／濾過層の見かけ体積）｝×１００
【００３２】
（濾過精度、圧力損失、濾過ライフ）
循環式濾過性能試験機のハウジングに長さ２５０ｍｍのフィルターカートリッジ１本を取り付け、ポンプで流量を毎分２５リットルに調節して通水循環する。この時のハウジング入口側と出口側の圧力差を測定し圧力損失（ＭＰａ）とした。次に循環している水にＪＩＳ−Ｚ−８９０１に定められた試験用粉体Ｉの７種（ＪＩＳ７種と略す。中位径：２７〜３１μｍ）を０．５ｇ／分で連続添加し、添加開始から１０分後に原液と濾液を採取する。採取した液を適当な倍率で希釈した後にそれぞれの液に含まれる粒径毎の粒子数を光遮断式粒子検出器を用いて粒径毎の捕集効率を算出した。次にその値を内挿して、捕集効率８０％と９８％を示す粒径を求めそれぞれを濾過精度▲１▼、濾過精度▲２▼（μｍ）とした。また、ケーキ添加開始から０．２ＭＰａに達した時のケーキ添加時間を濾過ライフ（分）とした。
【００３３】
（初期濾液の泡立ち及び繊維脱落）
循環式濾過性能試験機のハウジングに長さ２５０ｍｍのフィルターカートリッジ１本を取り付け、ポンプで流量を毎分１０リットルに調節してイオン交換水を通水する。ハウジング出口で初期濾液を５リットル採取した内の２５ｃｃを比色瓶に移して激しく攪拌し、攪拌停止１０秒後に泡立ちをみた。泡の体積（液面から泡の頂点までの体積）が１０ｃｃ以上ある場合を×、１ｃｃ以上１０ｃｃ未満の場合を△、１ｃｃ未満の場合を○として泡立ちを判定した。また、初期濾液の内０．５リットルを孔径０．８μｍのニトロセルロース濾紙で濾過し、濾紙上に長さ１ｍｍ以上の繊維が２０本以上ある場合を×、１０〜１９本の場合を△、５〜９本の場合を○、４本以下の場合を◎として繊維脱落を判定した。
【００３４】
（実施例１）
原反不織布として、繊度２．１ｄｔｅｘのポリプロピレン繊維７０％と、繊度２．４ｄｔｅｘのレーヨン繊維３０％からなり、目付２８．１ｇ／ｍ²、不織布面積の２０％が熱エンボスロールで熱圧着されたカード法による不織布を使用した。この原反不織布を幅４ｃｍでスリットした後、加圧された刃付きロールとゴムロールの間に通すことで、図３（Ａ）に示すようなＶ字型の切れ込みを１ｍ当たり８０ヶ所入れて、舌片部面積率２０％の舌片部含有帯状不織布とした。また、有孔筒状体として、内径３０ｍｍ、外径３４ｍｍ、長さ２５０ｍｍのポリプロピレン製射出成型品を使用した。舌片部先端が巻き取り方向を向くように舌片含有帯状不織布繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．２ｍｍ、濾過層空隙率８１％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。紡績糸を用いた比較例１と比べると、濾過精度▲２▼が上がっており、濾過ライフも向上している。また、繊維脱落も減少している。
【００３５】
（実施例２）
原反不織布として、繊度２．２ｄｔｅｘ、高密度ポリエチレンを鞘成分、ポリプロピレンを芯成分とした鞘芯比５：５の鞘芯型複合繊維４０％と、繊度２．１ｄｔｅｘの綿６０％からなり、目付２５．３ｇ／ｍ²、繊維交点が熱風貫流式加熱機で熱接着されたカード法による不織布を使用した。この原反不織布を幅４ｃｍでスリットした後、実施例１と同じ装置で刃付きロールを交換することで、図３（Ａ）に示すようなＶ字型の切れ込みを１ｍ当たり１００ヶ所入れて、舌片部面積率３５％の舌片部含有帯状不織布とした。また、有孔筒状体として、実施例１と同じものを使用した。舌片部先端が巻き取り方向を向くように舌片含有帯状不織布繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．０ｍｍ、濾過層空隙率８３％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。舌片部面積率数が増えたことで、濾材の捕集面積が増え、実施例１より濾過ライフが向上した。また、熱風貫流式加熱機で加工したことで熱接合点が増えたため、実施例１に比べ繊維の脱落が減少した。
【００３６】
（実施例３）
原反不織布として、繊度２．４ｄｔｅｘ、高密度ポリエチレンを鞘成分、ポリエステルを芯成分とした鞘芯比５：５の鞘芯型複合繊維１００％からなり、目付２０．３ｇ／ｍ²、不織布面積の１５％が熱エンボスロールで熱圧着されたスパンボンド法による不織布を使用した。この原反不織布を幅５ｃｍでスリットした後、実施例１と同じ装置で刃付きロールを交換することで、図２（Ｂ）に示すような不織布両サイドからの切れ込みを１ｍ当たり両側で１００ヶ所入れて、舌片部面積率４０％の舌片部含有帯状不織布とした。また、有孔筒状体として、実施例１と同じものを使用した。舌片部先端が巻き取り方向を向くように舌片含有帯状不織布繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．３ｍｍ、濾過層空隙率８２％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。スパンボンド法による長繊維不織布を用いたことで、泡立ちがなくなり、実施例１に比べ繊維の脱落が減少した。
【００３７】
（実施例４）
原反不織布として、繊度２．０ｄｔｅｘ、線状低密度ポリエチレンを鞘成分、ポリプロピレンを芯成分とした鞘芯比５：５の鞘芯型複合繊維１００％からなり、目付２２．３ｇ／ｍ²、不織布面積の１２％が熱エンボスロールで熱圧着されたスパンボンド法による不織布を使用した。この原反不織布を幅５ｃｍでスリットした後、実施例３と同じ装置で同じ切れ込みを入れ、舌片部面積率４０％の舌片部含有帯状不織布とした。次に、この舌片部含有帯状不織布を加撚機にかけて巻き取ることで、撚り数８０回／ｍの集束物とした。また、有孔筒状体として、実施例１と同じものを使用した。舌片部先端が巻き取り方向を向くように舌片部含有帯状不織布集束物を繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．５ｍｍ、濾過層空隙率８３％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。撚りを加えたことで舌片部による効果が向上し、実施例３より濾過ライフが向上した。
【００３８】
（実施例５）
原反不織布として、繊度０．０６ｄｔｅｘのポリプロピレン繊維１００％からなり、目付６ｇ／ｍ²のメルトブロー法による不織布の両面に、繊度２．４ｄｔｅｘのポリプロピレン繊維１００％からなり、目付１２ｇ／ｍ²のスパンボンド法による不織布が積層され、この積層不織布面積の１２％が熱エンボスロールで熱圧着された不織布を使用した。この原反不織布を幅５ｃｍでスリットした後、実施例２と同じ装置で同じ切れ込みを入れて、舌片部面積率３５％の舌片部含有帯状不織布とした。次に、この舌片部含有帯状不織布を加撚機にかけて巻き取ることで、撚り数６０回／ｍの集束物とした。また、有孔筒状体として、実施例１と同じものを使用した。舌片部先端が巻き取り方向を向くように舌片部含有帯状不織布繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．３ｍｍ、濾過層空隙率８２％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。不織布に細繊度の繊維が含まれることで実施例３より濾過精度が上がっており、撚りをかけたことで舌片部の効果が上がり、実施例３に近い濾過ライフを示している。
【００３９】
（実施例６）
実施例４と同じ舌片部含有帯状不織布を使用した。次に、この舌片部含有帯状不織布を加撚機にかけて巻き取ることで、撚り数８０回／ｍの集束物とした。また、有孔筒状体として、実施例１と同じものを使用した。先ず、繊度０．１ｄｔｅｘ、目付２４．８ｇ／ｍ²のポリプロピレン繊維からなるメルトブロー法による広幅の不織布を有孔筒状体に２周巻き付けた後、その上に、実施例４で得た舌片含有帯状不織布集束物を先端が巻き取り方向を向くように繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．５ｍｍ、濾過層空隙率８３％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。内層に細繊度の不織布を挿入することで濾過精度が上がっているにも係わらず、撚りを加えた舌片部含有帯状不織布を用いたことで舌片部の効果により、濾過精度のかなり低い比較例１と同等の濾過ライフを示している。
【００４０】
（比較例１）
舌片部含有帯状不織布のかわりに、繊度２．２ｄｔｅｘのポリプロピレン繊維１００％からなる１０７８ｔｅｘの紡績糸を使用し、スピンドル回転数８００ｒｐｍで、実施例１と同じ有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．０ｍｍ、濾過層空隙率８２％の円筒状フィルターカートリッジを得た。濾過性能の測定結果を表１に示す。濾過精度▲１▼、濾過精度▲２▼ともに低く、その差が大きいことから分別性に劣っている。また、泡立ちと濾材の脱落が非常に多かった。
【００４１】
（比較例２）
実施例１の原反不織布を４ｃｍ幅にスリットし、実施例１と同じ有孔筒状体にスピンドル回転数８００ｒｐｍで、外径６２ｍｍになるまで巻き取り、糸間隔１．０ｍｍ、濾過層空隙率８０％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。実施例１に比べ、濾過精度▲１▼は同等であるが分別性が劣り、濾過ライフも劣っていた。
【００４２】
（比較例３）
原反不織布として、鞘側が高密度ポリエチレン、芯側がポリプロピレンからなり鞘芯比５：５で繊度２．２ｄｔｅｘの鞘芯型複合繊維２０％と、繊度２．１ｄｔｅｘの綿８０％からなり、目付２４．５ｇ／ｍ²、繊維交点が熱風貫流式加熱機で熱接着されたカード法による不織布を使用した。この原反不織布を実施例２と同じ製法で加工することで同じ舌片部面積率の舌片部含有帯状不織布とした。次に、この舌片部含有帯状不織布を加撚機にかけて巻き取ることで、撚り数１８０回／ｍの集束物とした。また、有孔筒状体として、実施例１と同じものを使用した。舌片部先端が巻き取り方向を向くように舌片部含有帯状不織布繰り出し、スピンドル回転数８００ｒｐｍで、有孔筒状体に外径６２ｍｍになるまで巻き取り、糸間隔１．７ｍｍ、濾過層空隙率７７％の筒状フィルターを得た。濾過性能の測定結果を表１に示す。撚りを加え過ぎたことで、集束物の空隙率が低下し、実施例２よりも、初期圧力損失が大きくなり、濾過精度▲２▼が低下した。また、濾過ライフも劣っていた。更に、熱可塑性繊維の割合が少ないため、繊維脱落が多くなり、綿に含まれる繊維仕上げ剤の影響で泡立ちも多くなった。
【００４３】
【表１】

【００４４】
【発明の効果】
本発明の筒状フィルターは、従来の糸巻き型筒状フィルターに較べ、通水性、捕集効率、濾過ライフ共に優れており、更に、粗い精度側の捕集効率低下を防ぐため、分別性に優れている。また、繊維の脱落が少なく、スパンボンド法やメルトブロー法による不織布を用いたものは泡立ちがみられない。
【図面の簡単な説明】
【図１】本発明に係る筒状フィルターの斜視図である。
【図２】本発明で用いられる舌片部含有帯状不織布を説明するための図で、帯状不織布サイドに舌片部が形成された例を示す図面である。
【図３】本発明で用いられる舌片部含有帯状不織布を説明するための図で、帯状不織布面内に形成された舌片部の例を示す図面である。
【図４】図２で示される舌片部の面積を示す図面である。
【図５】図３で示される舌片部の面積を示す図面である。
【図６】舌片部含有帯状不織布をトラバースガイドに通して巻き付ける様子を示す説明図である。
【符号の説明】
１舌片部含有帯状不織布
２切れ込み（不織布を除去して形成した場合も含む）
３舌片部
４帯状不織布のエッジ
５筒状フィルター
６有孔筒状体
７舌片部含有帯状不織布の集束物
８糸間隔
９スピンドル
１０トラバースガイド
Ａ舌片部含有帯状不織布の巻き付け方向
Ｂ、Ｂ’ トラバースガイドの移動方向
Ｃスピンドルの回転方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical filter for liquid filtration. Specifically, a liquid-permeable material is formed by winding a strip-shaped nonwoven fabric containing thermoplastic fibers, at least a part of the fiber intersections of which are bonded, and provided with tongue pieces by a method such as cutting, in a twill shape around a perforated cylindrical body. The present invention relates to a cylindrical filter having good filtration performance such as property, filtration life and filtration accuracy.
[0002]
[Prior art]
Currently, various filters are used in various industrial fields to filter foreign substances in fluids. In particular, cartridge type filters that can be easily replaced (hereinafter referred to as cylindrical filters) remove foreign substances contained in various liquid raw materials, remove suspended particles generated in plating solutions and etching solutions, It is used in a wide range of fields, such as removal of aggregates generated in water, purification of industrial water and pool water. Among cylindrical filters, a thread-wound cylindrical filter is well known, which is made by winding a spun yarn as a filter medium in a twill shape around a perforated cylindrical core. In the case of a spool-type cylindrical filter, when adjusting the grade of filtration accuracy, the speed of the traverse relative to the number of rotations of the core around which the spun yarn is wound is changed, and the distance between the spun yarns is adjusted to change the bobbin shape. The filtration accuracy is adjusted. For this reason, it is not necessary to prepare various kinds of spun yarns, and since they are easy to manufacture and inexpensive, they have been used for a long time, and a very large number is still used.
[0003]
However, this spool-type cylindrical filter has several drawbacks. For example, the filter particle collecting method collects particles at the opening portion of the spun yarn itself, and also collects particles at the fuzz generated from the spun yarn and the gap between the spun yarns. Since the generated amount and the gap between the spun yarns are likely to vary, there is a disadvantage that the variation in the filtration accuracy of the product is large and it is difficult to finely separate the filtration accuracy of the spun yarn. In addition, since there is a limit to the fineness of the fibers used in the spun yarn, it is difficult to increase the accuracy of filtration. Furthermore, if the distance between the spun yarns is too wide, the particles cannot be collected sufficiently. There is also a limit to the direction of coarsening accuracy. As a result, there is a limit to the range of filtration accuracy that can be produced with a spool-type cylindrical filter using spun yarn. Furthermore, since the spun yarn is made by twisting short fibers, there is a drawback that when the liquid is filtered, the fibers are dropped from the spun yarn and mixed into the filtrate.
[0004]
As a method for solving the problems of such a conventional pincushion type cylindrical filter, for example, in Japanese Utility Model Publication No. 6-7767, a tape-like paper or nonwoven fabric having a taper shape is added while twisting. A pincushion type cylindrical filter has been proposed in which a filter material whose diameter is restricted to about 3 mm is tightly wound around a porous inner cylinder with a twill. Also, by increasing the winding pitch toward the outside from the porous inner cylinder, large particles can be collected on the outside, and small particles can be collected at the center of the filter medium, so that a filtering effect can be obtained over a long period of time. You can do that. However, since the filtration material is squeezed and squeezed, the porosity of the filtration material is lowered, the amount of particles trapped in the filtration material itself is small, and the liquid permeability is also lowered. Moreover, since the gap between the filtration materials is small due to the close winding, there is no space for easy passage of liquid, and the liquid permeability of the filter itself is lowered. In addition, by increasing the outer winding pitch, large particles are collected in the gap between the filtration materials, but since there are only a few gaps that are effective for collecting particles, even if the gap is given a gradient, The amount of collected particles does not increase, the surface is easily clogged, and the filtration life becomes very short. Furthermore, in order to make a filter with coarse filtration accuracy, if the same filtration material is wound at an interval, the filtration material does not have fluff like spun yarn, so particles flow out from the gap between the filtration materials. The coarser particles should increase the collection efficiency, but the result is that the collection efficiency reaches a certain level while the collection efficiency is low, or the collection efficiency of coarse particles decreases. For this reason, in order to make a filter with different filtration accuracy, it is necessary to prepare tape-like paper and nonwoven fabric with different fiber diameters and void ratios for each filtration accuracy, leading to a decrease in productivity and an increase in raw material costs. I will.
[0005]
As another method, Japanese Patent Laid-Open No. 4-45810 discloses a slit nonwoven fabric made of a composite fiber in which 10% by weight or more of the constituent fibers are divided into 0.5 denier or less, and the fiber density on the porous core cylinder is 0.18-0.30 g / cm ^Three A wind filter that has been wound around is proposed. When this method is used, there is a feature that fine particles in the liquid can be captured by fibers having a small fineness. However, in order to divide the composite fiber, it is necessary to apply physical stress such as high-pressure water flow, and it is difficult to divide the entire nonwoven fabric uniformly, and if it is not uniformly divided and thick fibers remain, they are trapped in the nonwoven fabric. Since a portion with poor collection efficiency occurs, the filtration accuracy of the entire filter is lowered. In addition, the cost of spinning the split fibers and the production cost required for splitting are higher than ordinary spun yarn, which increases the price of the filter. It is no longer suitable for the field.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a pincushion type cylindrical filter having good filtration performance such as liquid permeability, filtration life, and filtration accuracy, in which the above-mentioned problems are solved.
[0007]
[Means for Solving the Problems]
As a result of intensive studies, the inventors of the present invention have made a strip-shaped nonwoven fabric containing a thermoplastic fiber, bonded at least part of the fiber intersection, and provided with a notch that becomes a tongue piece portion in a perforated cylindrical body in a twill shape. The present invention has been completed by finding that a cylindrical filter to be wound solves the above problems.
The present invention has the following configuration.
(1) A cylindrical filter formed by winding a belt-shaped nonwoven fabric having a tongue piece portion, which includes thermoplastic fibers and at least a part of the fiber intersections, around a perforated cylindrical body.
(2) The cylindrical filter as described in (1) above, wherein the strip-shaped nonwoven fabric having a tongue piece is a nonwoven fabric containing at least 30% by weight of thermoplastic fibers.
(3) The cylindrical filter according to (1) or (2), wherein the belt-shaped nonwoven fabric having a tongue piece is thermocompression bonded with a hot embossing roll.
(4) The cylindrical filter according to any one of (1) to (3), wherein at least a part of the fiber intersections of the belt-shaped nonwoven fabric having a tongue piece is thermally bonded.
(5) The cylindrical filter according to any one of (1) to (4), wherein the area ratio of the tongue piece portion to the entire area of the strip-shaped nonwoven fabric having the tongue piece portion is 10 to 80%.
(6) The cylindrical filter according to any one of (1) to (5), wherein a twist is added to a belt-shaped nonwoven fabric having a tongue piece.
(7) The cylindrical filter according to any one of (1) to (6), wherein the porosity of the filtration layer of the cylindrical filter is 65 to 90%.
(8) The cylindrical filter according to any one of (1) to (7), wherein the belt-shaped nonwoven fabric having a tongue piece is a nonwoven fabric composed of long fibers.
(9) The above-mentioned (1) to (8), wherein the thermoplastic fiber constituting the strip-shaped nonwoven fabric having the tongue piece portion is composed of a low-melting resin and a high-melting resin, and the difference between the melting points of these resins is a composite fiber having a melting point of 10 ° C or higher. The cylindrical filter of any one of claim | items.
(10) The cylindrical filter according to any one of (1) to (9), wherein a porous material other than a strip-shaped nonwoven fabric having a tongue piece portion as a part of a filtration layer of the cylindrical filter is used.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described below.
The cylindrical filter of the present invention contains thermoplastic fibers, at least a part of the fiber intersections are bonded, and after the band-shaped nonwoven fabric having tongue pieces as shown in FIGS. 2 and 3 is focused, It is the cylindrical filter 5 wound by the perforated cylindrical body 6 as shown in FIG. By using a strip-shaped non-woven fabric having a tongue piece as a material for the filtration layer of the cylindrical filter, the tongue piece is present in the gap formed by the converged material of the strip-shaped nonwoven fabric. Particles that could not be collected are collected on the tongue piece, and the collection efficiency is improved. Furthermore, the amount of particles collected increases due to the increase in the particle collection area due to the unevenness of the tongue piece, so that the cylindrical filter The filtration accuracy, the filtration life, etc. are excellent.
[0009]
As a material for the cylindrical filter of the present invention, a belt-like nonwoven fabric having a tongue piece portion (hereinafter referred to as a tongue piece portion-containing belt-like nonwoven fabric) containing thermoplastic fibers and having at least a part of the fiber intersections adhered thereto is used. It is done.
The tongue piece-containing band-shaped nonwoven fabric is a method in which an untreated nonwoven fabric (hereinafter referred to as a raw nonwoven fabric) is made to have a desired width by a slit or the like and then cut between a pressurized bladed roll and a rubber roll. It is obtained by. The slit or the like may be performed after cutting the raw nonwoven fabric.
In the following description, the term “nonwoven fabric” means a generic term for the above-mentioned tongue piece-containing belt-shaped nonwoven fabric and raw fabric nonwoven fabric.
[0010]
As the raw material of the thermoplastic fiber, a thermoplastic resin capable of melt spinning can be used. Examples thereof include polypropylene, low density polyethylene, high density polyethylene, linear low density polyethylene, copolymers of propylene and ethylene, propylene / ethylene / butene-1 copolymers, and two or more of propylene and other α-olefins. Polyolefin resin, polyethylene terephthalate, polybutylene terephthalate, polymerized using Ziegler-Natta catalysts such as terpolymers and metallocene catalysts, and isophthalic acid in addition to terephthalic acid. Low melting point polyesters, polyamide resins such as nylon-6 and nylon-66, polystyrene resins such as polystyrene and syndiotactic polystyrene, biodegradable resins such as polyurethane elastomers, polyester elastomers, and lactic acid polyesters Etc. Can, be used in these thermoplastic resins alone or may be used as a mixture of two or more.
Moreover, when forming a raw fabric nonwoven fabric using the said thermoplastic fiber, the said thermoplastic fiber can be used individually or in mixture of 2 or more types.
[0011]
When the thermoplastic fiber is a thermoplastic composite fiber composed of a low-melting point resin and a high-melting point resin having a melting point difference of 10 ° C. or higher, preferably 15 ° C. or higher, heat bonding or the like ensures reliable thermal bonding at the fiber bonding point of the raw nonwoven fabric. Can be done. The upper limit of the melting point difference is not particularly limited, but the temperature difference between the highest melting point resin and the lowest melting point resin among the thermoplastic resins that can be melt-spun is applicable. In the case of a resin having no clear melting point, the flow start temperature is regarded as the melting point. The form of the composite fiber may be a form in which the low melting point resin is present on at least a part of the fiber surface, such as a parallel type or a sheath core type.
[0012]
The combination of the low melting point resin and the high melting point resin of the composite fiber is not particularly limited as long as the difference in melting point is 10 ° C. or more, preferably 15 ° C. or more. For example, linear low density polyethylene / polypropylene, high density polyethylene / polypropylene, low density polyethylene / polypropylene, copolymer of propylene and other α-olefin / polypropylene, linear low density polyethylene / high density polyethylene, low density Polyethylene / high density polyethylene, linear low density polyethylene / polyethylene terephthalate, polypropylene / polyethylene terephthalate, low melting point polyester / polyethylene terephthalate copolymerized with ethylene glycol and terephthalic acid and isophthalic acid as acid components -G, nylon 6 / nylon 66, etc. In particular, a polyolefin resin / polyolefin resin having excellent chemical resistance, a polyolefin resin / polyethylene terephthalate, and the like are preferably used. Moreover, you may use 2 or more types of mixed resin for either component of a composite fiber, or both components.
[0013]
The nonwoven fabric used in the present invention preferably contains at least 30% by weight of thermoplastic fibers. Of course, this thermoplastic fiber may be 100% by weight. By including the thermoplastic fiber, it becomes possible to thermally bond the fibers described later, and performances such as water permeability, chemical resistance, and prevention of filter medium falling are improved as compared with the case where the fibers are bonded with various binders. If the thermoplastic fiber contained in the non-woven fabric is less than 30% by weight, the strength and number of fiber bonding points when heat-bonded by thermocompression treatment or through-air heat treatment are not sufficient, and the fibers fall off during filtration. It becomes easy to be mixed into the filtrate. Moreover, fibers other than thermoplastic fibers can be used for the nonwoven fabric within a range of 70% by weight or less. Examples of fibers other than the thermoplastic fiber include rayon, cupra, cotton, hemp, pulp, carbon fiber, metal fiber, and the like.
[0014]
Although the single yarn fineness of the fiber used for forming the nonwoven fabric varies depending on the use of the cylindrical filter and the required filtration performance, 0.01 to 500 dtex is preferable. Examples of the nonwoven fabric formed by the fibers include long fiber nonwoven fabrics, short fiber nonwoven fabrics, nonwoven fabrics in which long fibers and short fiber nonwoven fabrics are mixed, and laminated nonwoven fabrics in which these nonwoven fabrics are combined. It can be used as a material for cylindrical filters.
Examples of types of non-woven fabrics by production method include spunbond non-woven fabric, melt blown non-woven fabric, tow-opening non-woven fabric, airlaid non-woven fabric, card method non-woven fabric, and high-pressure water-entangled non-woven fabric, all of which are tubular filters of the present invention. It can be used for any material. In particular, the spunbond nonwoven fabric and the melt blown nonwoven fabric do not contain a fiber finish that causes foaming of the filtrate, and thus are effective for filtration applications that dislike this. Furthermore, these non-woven fabrics may contain activated carbon, ion exchange resins, bactericides and the like by binders, heat bonding methods, resin kneading methods, and the like.
[0015]
Adhesion of the fiber intersections of the nonwoven fabric is performed by using a device such as a hot embossing roll, a heat flat calender roll, or an ultrasonic embossing, hot-pressed, hot air flow-through type, vertical hot air jet type, infrared heater type, etc. The thing etc. which heat-bonded using the heat processing machine can be illustrated. Moreover, when the said nonwoven fabric is a hot embossing roll crimping | compression-bonding nonwoven fabric, it is desirable that the thermocompression bonding area ratio which is a ratio of the embossing thermocompression bonding area with respect to the total area of a nonwoven fabric part is 5 to 30%, More preferably, it is 5 to 25%. When the area ratio of thermocompression bonding is less than 5%, there are few bonded parts at the intersections of fibers, so that the dropout of the fibers increases or the strength of the nonwoven fabric decreases. It is easy to do, and what has uniform filtration performance cannot be obtained. Moreover, when the thermocompression-bonding area rate exceeds 30%, the liquid permeability and filtration life of a cylindrical filter will fall.
[0016]
The porosity of the raw fabric nonwoven fabric is 60 to 95%, more preferably 65 to 92%. When a strip-like nonwoven fabric containing a tongue piece part obtained from a raw fabric nonwoven fabric having a porosity of 60 to 95% is used, the filtration layer of the tubular filter is suppressed from becoming unnecessarily dense, and pressure loss when used as a filter Is sufficiently suppressed, and the particle collection efficiency can be further improved. Moreover, by setting the porosity of the raw nonwoven fabric to 95% or less, it becomes easy to wind the strip-shaped nonwoven fabric containing the strip-shaped nonwoven fabric around the effective cylindrical body, and the deformation due to the load pressure of the obtained cylindrical filter is further reduced. can do.
[0017]
As said tongue piece part containing strip | belt-shaped nonwoven fabric, what slit the wide raw fabric nonwoven fabric in strip | belt shape is used preferably. The width of the slit-shaped non-woven fabric is preferably 0.5 to 20 cm, more preferably 1 to 10 cm. If this width is less than 0.5 cm, the tongue-shaped portion-containing strip-shaped nonwoven fabric may be cut when wound around the perforated tubular body in a twill shape, and it is difficult to adjust the tension. Further, when the length exceeds 20 cm, when the tongue piece-containing belt-shaped nonwoven fabric is converged and wound around the perforated tubular body in a twill shape, the tongue piece portion is easily enclosed in the converged nonwoven fabric, and the effect of the tongue piece portion is obtained. It will not be fully demonstrated. The basis weight of the nonwoven fabric is 10 to 200 g / m. ² Is preferred. This value is 10 g / m ² If it becomes smaller than this, the amount of fibers decreases, so that the non-uniformity of the non-woven fabric increases, or the strength of the non-woven fabric decreases, making it difficult to process the filter. On the other hand, this value is 200 g / m. ² When it becomes larger than this, since the nonwoven fabric becomes thick, it becomes difficult to form the tongue piece.
[0018]
Next, the tongue piece will be described. The tongue piece is formed by cutting a part of the strip-shaped nonwoven fabric or removing a part of the nonwoven fabric. As an example of a tongue piece part, the shape which put the notch 2 used as the tongue piece part 3 from the edge 4 of a strip | belt-shaped nonwoven fabric like FIG. 2 (A) (B) (C), FIG. 3 (A) (B) The shape which put the notch 2 of the shape used as the tongue piece part 3 in the surface of a strip | belt-shaped nonwoven fabric like (C) is shown. The lengths and sizes of the tongue pieces 3 formed on the belt-shaped nonwoven fabric may not all be the same, and the direction, shape, direction of the cuts 2 and the like may be mixed, or FIG. 2 and FIG. A combination of the three shapes may be used. Moreover, the position of the tongue piece part 3 in the strip-shaped nonwoven fabric 1 may not be bilaterally symmetric with respect to the length direction, and may be arranged only on one side. However, when the direction in which the strip-shaped non-woven fabric 1 is wound around the perforated tubular body is upstream and the reverse direction is downstream, the shape as shown in FIG. 2 is cut from the upstream side to the downstream side. 3 and the shape shown in FIG. 3, when the belt-like nonwoven fabric is squeezed through the guide of the winder when the portion connected to the belt-like nonwoven fabric is on the downstream side and wound around the perforated tubular body 3 is easy to stand, and the effect of the tongue piece 3 is more remarkable, which is desirable.
[0019]
As an example of a method for forming the tongue piece on the belt-shaped nonwoven fabric, a press mold having a blade for making a cut to become the tongue piece portion is used, and the belt-shaped nonwoven fabric is passed through a continuous press machine for tape in which this mold is set. Method, a method of passing a strip-shaped nonwoven fabric while being pressed with a flat roll and a roll having a blade for making a cut into a tongue piece on one side, a method of cutting with a high-pressure water flow, or pressing a heated blade, A method of melting and removing with a laser beam can be used. In addition, after processing a tongue piece part in an original fabric nonwoven fabric, it is good also as slitting and making a tongue piece part containing strip | belt-shaped nonwoven fabric.
[0020]
The total area of the tongue piece portion is 10 to 80% with respect to the total area of the tongue piece-containing belt-shaped nonwoven fabric. In addition, when the nonwoven fabric is removed, the area of the part is not included in the calculation. If the area ratio of the tongue piece is less than 10%, the filtration accuracy and filtration life of the tongue piece will not be improved, and if it exceeds 80%, the strength of the strip-shaped nonwoven fabric containing the tongue piece will be reduced. It becomes difficult to process. In addition, the area of the tongue piece part said here is about the shape like FIG. 2, as shown in FIG. 4 (A) or (B), the edge 4 of the strip-shaped nonwoven fabric, the notch 2, and both ends of the notch 2 For the hatched portion surrounded by a line connecting the parts (shown by a broken line), as shown in FIG. 3, the notch 2 and the tip of the notch 2 are connected as shown in FIG. 5 (A) or (B). The hatched portion surrounded by an ellipse (shown by a broken line) corresponds to this.
[0021]
A method of winding the tongue piece-containing band-shaped nonwoven fabric around a perforated tubular body after twisting is also preferably used. When twist is added to the strip-shaped non-woven fabric containing the tongue piece, the tongue piece stands up against the non-woven strip containing the tongue piece, and the state is firmly held. Will improve. Moreover, since the porosity of a tongue piece part containing strip | belt-shaped nonwoven fabric can be changed with the number of twists per unit length, the filtration precision can be adjusted. The number of twists is preferably in the range of 15 to 150 times per 1 m of the strip-shaped non-woven fabric. When this value is smaller than 15 times, the effect of twisting is hardly obtained. On the other hand, if this value is more than 150 times, the tongue piece-containing belt-shaped nonwoven fabric is strongly squeezed and the fibers are clogged, and the water permeability and particle trapping property are deteriorated.
[0022]
Next, the manufacturing method of a cylindrical filter is demonstrated using FIG. A perforated tubular body 6 is mounted on a spindle 9 of a winder, and a strip-like non-woven fabric 1 containing a tongue piece passing through a yarn path of the winder is wound around and fixed to the end of the winder. With the rotation of the spindle 9 in the C direction, the tongue piece-containing strip-shaped nonwoven fabric 1 is wound in a traverse shape in the B and B ′ directions by the traverse guide 10 and wound. The winding conditions at that time may be set according to the conditions of a normal pincushion filter. For example, the spindle rotation speed may be 500 to 1500 rpm, the feeding speed may be adjusted, and winding may be performed while applying an appropriate tension. The density gradient type cylindrical shape in which the porosity of the filtration layer is changed by adjusting the tension at the time of winding to increase the porosity of the inside of the cylindrical filter and gradually reducing the tension of the middle layer and outer layer. A filter can also be obtained. If this method is used, the filtration life by depth filtration can be improved. The filtration accuracy can also be changed by changing the winding pattern by adjusting the ratio of the traverse guide traverse speed and the spindle rotation speed. The pattern can be applied by using a known conventional method of a wound-pipe-type cylindrical filter, which is wound around a certain thread (in the present invention, a bundle of tongue-shaped strip-containing nonwoven fabrics 7) and a layer below it. Filtration accuracy is coarse when the yarn spacing 8 to the warp is wide, and conversely fine when it is narrow. By these methods, the strip-shaped non-woven fabric containing the tongue piece is wound to an outer diameter of about 1.5 to 3 times the outer diameter of the perforated cylindrical body, and formed into a cylindrical filter. This may be used as a filter as it is, or the adhesiveness between the filter end surface and the housing may be improved by attaching a foamed polyethylene gasket having a thickness of about 3 mm to the end surface.
[0023]
In the present invention, the perforated cylindrical body serves as the core material of the cylindrical filter, and the material and shape thereof are particularly limited as long as they have strength to withstand external pressure during filtration and the pressure loss is not extremely high. It is not something. For example, what processed the thermoplastic resin, such as a polypropylene, into the cylindrical body which has a grid | lattice-shaped opening part, the thing processed similarly ceramic and stainless steel, etc. may be used. Moreover, you may use other types of filters with a small outer diameter, such as a pleated filter in which the filter medium is fold-folded and a nonwoven fabric wound filter.
[0024]
In the present invention, the porosity of the filtration layer of the cylindrical filter is preferably in the range of 65 to 90%. When this value is less than 65%, the fiber density becomes too high, and the liquid permeability is lowered. When the porosity is greater than 90%, the strength of the filtration layer becomes weak, and problems such as deformation of the filtration layer occur when the filtration pressure is high. As a method for adjusting the porosity, the width of the tongue piece-containing band-shaped nonwoven fabric, the number and size of the tongue pieces, the twisting amount of the tongue piece-containing band-shaped nonwoven fabric, the perforated tubular body of the tongue piece-containing band-shaped nonwoven fabric For example, tension when wound around.
[0025]
In this invention, you may use porous materials other than a tongue piece part containing strip | belt-shaped nonwoven fabric for a part of filtration layer of a cylindrical filter. Examples include polyethylene / polypropylene composite fiber nonwoven fabrics, melt blown ultrafine fiber nonwoven fabrics, polyethylene microporous membranes, polytetrafluoroethylene microporous membranes, nonwoven fabrics made of activated carbon fibers and antibacterial fibers, ion exchange resins, activated carbon, and the like. Nonwoven fabrics can be exemplified. By using a porous material other than such a tongue piece-containing belt-shaped nonwoven fabric, effects such as control of filtration accuracy and imparting functions such as antibacterial properties and metal ion adsorption properties can be obtained.
[0026]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. In each example, the evaluation of the filtration performance and the like of the nonwoven fabric and the obtained cylindrical filter was performed by the method described below.
[0027]
(Fabric weight of raw nonwoven fabric)
The area of the raw nonwoven fabric is 400cm ² Cut the strip-shaped non-woven fabric from three locations so that the weight is measured, and the average value is 1 m ² Per unit weight (g / m) ² ).
[0028]
(Fineness of raw nonwoven fabric)
Randomly sample 5 locations from the raw nonwoven fabric, photograph them with a scanning electron microscope, randomly select 20 fibers at each location, measure their fiber diameters, and calculate the average value The fiber diameter (μm) of the raw nonwoven fabric was used. The fineness (dtex) is the fiber diameter and density of the nonwoven fabric raw material (g / cm ^Three ) Was obtained from the following equation.
In addition, when two or more types of fibers were mixed, etc., the above measurement was performed for each fiber, and the fineness of each fiber was calculated.
(Fineness) = π (Fiber diameter) ² × (Density) / 400
[0029]
(Area ratio of the tongue piece part of the non-woven fabric containing the tongue piece part)
The area including the tongue piece part is 400 cm from the strip-like non-woven fabric containing the tongue piece part. ² Cut the strip-shaped non-woven fabric of the length to become the whole area of the tongue piece (unit cm) ² ) And the tongue piece area ratio (%) was calculated from the following equation.
(Lingual piece area ratio) = {(Total area of tongue piece) / 400 cm ² } × 100
[0030]
(Thread spacing of the filtration layer of the cylindrical filter)
The interval between the strip-shaped nonwoven fabric bundle (or the filament wound around the perforated tubular body in the following embodiment) on the surface layer and the strip-shaped nonwoven fabric bundle wound on the layer immediately below (FIG. 1). 10) was measured for each cylindrical filter, and the average value was defined as the thread interval (mm). In addition, it measured except the part which has come out as a tongue piece part.
[0031]
(Porosity of filtration layer of cylindrical filter)
The outer diameter, inner diameter, length, and weight of the cylindrical filter were measured, and the porosity (%) was obtained using the following equation. In order to determine the porosity of the filtration layer itself, the outer diameter of the perforated tubular body was used as the inner diameter value, and the weight of the perforated tubular body was subtracted from the weight of the tubular filter as the value of the filtration layer weight. Values were used.
(Apparent volume of filtration layer) = π {(filter cartridge outer diameter) ² -(Filtration bed inner diameter) ² } X (filter cartridge length) / 4
(True volume of filtration layer) = (weight of filtration layer) / (density of raw material of filtration layer)
(Void ratio of filtration layer) = {1− (true volume of filtration layer) / apparent volume of filtration layer)} × 100
[0032]
(Filtration accuracy, pressure loss, filtration life)
A filter cartridge with a length of 250 mm is attached to the housing of the circulating filtration performance tester, and the water flow is circulated by adjusting the flow rate to 25 liters per minute with a pump. At this time, the pressure difference between the inlet side and the outlet side of the housing was measured to obtain a pressure loss (MPa). Next, 7 kinds of test powder I defined in JIS-Z-8901 (abbreviated as JIS 7 type; median diameter: 27 to 31 μm) are continuously added to the circulating water at 0.5 g / min. Collect the stock solution and the filtrate 10 minutes after the start of the addition. After the collected liquid was diluted at an appropriate magnification, the number of particles for each particle diameter contained in each liquid was calculated for the collection efficiency for each particle diameter using a light blocking particle detector. Next, the values were interpolated to obtain particle diameters having a collection efficiency of 80% and 98%, which were designated as filtration accuracy (1) and filtration accuracy (2) (μm), respectively. The cake addition time when the pressure reached 0.2 MPa from the start of cake addition was defined as the filtration life (minutes).
[0033]
(Initial filtrate foaming and fiber dropping)
A filter cartridge with a length of 250 mm is attached to the housing of the circulating filtration performance tester, and the flow rate is adjusted to 10 liters per minute with a pump, and ion exchange water is passed through. Of the 5 liters of the initial filtrate collected at the outlet of the housing, 25 cc was transferred to a colorimetric bottle and stirred vigorously, and foaming was observed 10 seconds after stirring was stopped. Foaming was determined when the foam volume (volume from the liquid surface to the top of the foam) was 10 cc or more, x was 1 cc or more and less than 10 cc, and △ was less than 1 cc. Further, 0.5 liter of the initial filtrate was filtered with a nitrocellulose filter paper having a pore diameter of 0.8 μm, and when there were 20 or more fibers having a length of 1 mm or more on the filter paper, ×, when 10 to 19 fibers were Δ, The case of 5-9 fibers was evaluated as ◯, and the case of 4 fibers or less was evaluated as ◎.
[0034]
Example 1
The raw nonwoven fabric is composed of 70% polypropylene fiber with a fineness of 2.1 dtex and 30% rayon fiber with a fineness of 2.4 dtex, and has a basis weight of 28.1 g / m. ² A non-woven fabric by a card method in which 20% of the non-woven fabric area was thermocompression bonded with a hot embossing roll was used. After slitting this raw nonwoven fabric with a width of 4 cm, it is passed between a roll with pressure and a rubber roll so that 80 V-shaped cuts as shown in FIG. It was set as the strip-shaped nonwoven fabric containing the tongue piece part with a tongue piece part area ratio of 20%. In addition, a polypropylene injection-molded product having an inner diameter of 30 mm, an outer diameter of 34 mm, and a length of 250 mm was used as the perforated cylindrical body. The strip-shaped non-woven fabric is fed out so that the tip of the tongue piece portion faces the winding direction, wound at a spindle rotation speed of 800 rpm until the outer diameter is 62 mm, the thread interval is 1.2 mm, and the filtration layer porosity is An 81% cylindrical filter was obtained. Table 1 shows the measurement results of the filtration performance. Compared with Comparative Example 1 using spun yarn, the filtration accuracy (2) is increased and the filtration life is also improved. Also, fiber loss has decreased.
[0035]
(Example 2)
The raw fabric nonwoven fabric is composed of 40% sheath-core composite fiber having a sheath core ratio of 5: 5 having a fineness of 2.2 dtex, high-density polyethylene as a sheath component, and polypropylene as a core component, and 60% of cotton having a fineness of 2.1 dtex. 25.3 g / m ² A non-woven fabric by a card method in which fiber intersections were thermally bonded with a hot air flow-through type heater was used. After slitting the raw nonwoven fabric with a width of 4 cm, by replacing the bladed roll with the same apparatus as in Example 1, 100 V-shaped cuts as shown in FIG. A strip-shaped nonwoven fabric containing a tongue piece portion with a tongue piece area ratio of 35% was obtained. Moreover, the same thing as Example 1 was used as a porous cylindrical body. The strip-shaped non-woven fabric is fed out so that the tip of the tongue piece portion faces the winding direction, wound at a spindle rotation speed of 800 rpm until the outer diameter is 62 mm, the thread interval is 1.0 mm, and the filtration layer porosity is An 83% cylindrical filter was obtained. Table 1 shows the measurement results of the filtration performance. By increasing the number of tongue piece area ratios, the collection area of the filter medium was increased, and the filtration life was improved as compared with Example 1. Moreover, since the heat junction increased by processing with the hot air flow-through type heating machine, the dropout of the fibers decreased compared to Example 1.
[0036]
Example 3
As a raw fabric non-woven fabric, it is composed of 100% sheath core type composite fiber having a fineness of 2.4 dtex, a high density polyethylene as a sheath component, and a sheath core ratio of 5: 5 as a core component, and a basis weight of 20.3 g / m. ² A non-woven fabric by a spunbond method in which 15% of the non-woven fabric area was thermocompression bonded with a hot embossing roll was used. After slitting the raw nonwoven fabric with a width of 5 cm, the rolls with blades are exchanged with the same apparatus as in Example 1 so that cuts from both sides of the nonwoven fabric as shown in FIG. It was made into a strip-shaped non-woven fabric containing a tongue piece portion with a tongue piece area ratio of 40%. Moreover, the same thing as Example 1 was used as a porous cylindrical body. The strip-shaped non-woven fabric is fed out so that the tip of the tongue piece is directed in the winding direction, wound at a spindle speed of 800 rpm until the outer diameter is 62 mm, and the gap between the yarns is 1.3 mm, the filtration layer porosity An 82% cylindrical filter was obtained. Table 1 shows the measurement results of the filtration performance. By using the long-fiber nonwoven fabric by the spunbond method, foaming disappeared, and fiber dropout was reduced compared to Example 1.
[0037]
Example 4
As a raw fabric nonwoven fabric, it is composed of 100% sheath-core type composite fiber having a fineness of 2.0 dtex, a linear low density polyethylene as a sheath component, and a sheath core ratio of 5: 5 as a core component, and a basis weight of 22.3 g / m. ² A non-woven fabric by a spunbond method in which 12% of the non-woven fabric area was thermocompression bonded with a hot embossing roll was used. After slitting this raw fabric nonwoven fabric with a width of 5 cm, the same notch was made with the same apparatus as in Example 3 to obtain a tongue piece-containing belt-like nonwoven fabric having a tongue piece area ratio of 40%. Next, this tongue piece-containing strip-shaped non-woven fabric was wound on a twisting machine to obtain a bundle with a twist number of 80 times / m. Moreover, the same thing as Example 1 was used as a porous cylindrical body. The strip-shaped nonwoven fabric bundle containing the tongue piece portion is drawn out so that the tip of the tongue piece portion faces the winding direction, and wound at a spindle rotational speed of 800 rpm until the outer diameter is 62 mm, the thread interval is 1.5 mm, A cylindrical filter having a filtration layer porosity of 83% was obtained. Table 1 shows the measurement results of the filtration performance. By adding the twist, the effect of the tongue piece portion was improved, and the filtration life was improved from Example 3.
[0038]
(Example 5)
Made of 100% polypropylene fiber with a fineness of 0.06 dtex as a raw nonwoven fabric, the basis weight is 6 g / m ² Made of 100% polypropylene fiber with a fineness of 2.4 dtex on both sides of the nonwoven fabric produced by the melt-blowing method. ² The nonwoven fabric by which the nonwoven fabric by the spun bond method of this was laminated | stacked and 12% of this lamination | stacking nonwoven fabric area was thermocompression bonded with the hot embossing roll was used. After slitting this raw fabric nonwoven fabric with a width of 5 cm, the same notch was made with the same apparatus as in Example 2 to obtain a tongue piece-containing belt-like nonwoven fabric having a tongue piece area ratio of 35%. Next, the strip-shaped non-woven fabric containing the tongue piece portion was wound on a twisting machine to obtain a bundle having a twist number of 60 times / m. Moreover, the same thing as Example 1 was used as a porous cylindrical body. The strip-shaped non-woven fabric is fed out so that the tip of the tongue piece is directed in the winding direction, wound at a spindle rotation speed of 800 rpm until the outer diameter is 62 mm, the thread interval is 1.3 mm, and the filtration layer gap A cylindrical filter having a rate of 82% was obtained. Table 1 shows the measurement results of the filtration performance. Filtration accuracy is higher than in Example 3 because the non-woven fabric contains fibers of fineness, and the effect of the tongue piece portion is increased by applying twist, indicating a filtration life close to that of Example 3.
[0039]
(Example 6)
The same strip-like non-woven fabric containing tongue pieces as in Example 4 was used. Next, this tongue piece-containing strip-shaped non-woven fabric was wound on a twisting machine to obtain a bundle with a twist number of 80 times / m. Moreover, the same thing as Example 1 was used as a porous cylindrical body. First, a fineness of 0.1 dtex and a basis weight of 24.8 g / m ² After winding a wide nonwoven fabric made of polypropylene fiber by melt-blowing method around a perforated cylindrical body twice, the tip of the tongue-shaped strip-shaped nonwoven fabric bundle obtained in Example 4 is directed toward the winding direction. Then, the cylindrical filter was wound up at a spindle rotation number of 800 rpm until the outer diameter was 62 mm, and a cylindrical filter having a thread interval of 1.5 mm and a filtration layer porosity of 83% was obtained. Table 1 shows the measurement results of the filtration performance. Despite the fact that the filtration accuracy has been improved by inserting a non-woven fabric with fine fineness in the inner layer, a comparatively low filtration accuracy has been achieved due to the effect of the tongue piece by using the twisted strip-like non-woven fabric. The filtration life equivalent to Example 1 is shown.
[0040]
(Comparative Example 1)
Instead of the strip-shaped non-woven fabric containing the tongue piece, a 1078 tex spun yarn made of 100% polypropylene fiber having a fineness of 2.2 dtex was used, and the outer diameter was 62 mm in the same perforated cylindrical body as in Example 1 at a spindle rotation speed of 800 rpm. A cylindrical filter cartridge having a thread interval of 1.0 mm and a filtration layer porosity of 82% was obtained. Table 1 shows the measurement results of the filtration performance. Both the filtration accuracy (1) and the filtration accuracy (2) are low, and the difference between them is large. In addition, foaming and dropping of the filter media were very much.
[0041]
(Comparative Example 2)
The raw fabric nonwoven fabric of Example 1 was slit to a width of 4 cm, wound around the same perforated tubular body as in Example 1 at a spindle rotation speed of 800 rpm until the outer diameter reached 62 mm, the thread interval was 1.0 mm, and the filtration layer porosity was An 80% cylindrical filter was obtained. Table 1 shows the measurement results of the filtration performance. Compared with Example 1, the filtration accuracy (1) was the same, but the separability was poor and the filtration life was also poor.
[0042]
(Comparative Example 3)
As a raw fabric nonwoven fabric, the sheath side is made of high density polyethylene, the core side is made of polypropylene, the sheath core ratio is 5: 5, and the sheath core type composite fiber is 20% with a fineness of 2.2 dtex, and the fabric weight is 2.1 dtex with 80% cotton. .5g / m ² A non-woven fabric by a card method in which fiber intersections were thermally bonded with a hot air flow-through type heater was used. This raw nonwoven fabric was processed by the same manufacturing method as in Example 2 to obtain a tongue piece-containing belt-shaped nonwoven fabric having the same tongue piece area ratio. Next, the band-shaped nonwoven fabric containing the tongue piece portion was wound around a twisting machine to obtain a bundle having a twist number of 180 times / m. Moreover, the same thing as Example 1 was used as a porous cylindrical body. The strip-shaped non-woven fabric is fed out so that the tip of the tongue piece is directed in the winding direction, wound at a spindle rotation speed of 800 rpm until the outer diameter is 62 mm, the thread interval is 1.7 mm, and the filtration layer gap is A cylindrical filter with a rate of 77% was obtained. Table 1 shows the measurement results of the filtration performance. By adding too much twist, the porosity of the converging material decreased, the initial pressure loss was larger than in Example 2, and the filtration accuracy (2) was decreased. Moreover, the filtration life was also inferior. Furthermore, since the ratio of the thermoplastic fiber is small, fiber dropping increases, and foaming increases due to the influence of the fiber finishing agent contained in the cotton.
[0043]
[Table 1]

[0044]
【The invention's effect】
The cylindrical filter of the present invention is superior in water permeability, collection efficiency, and filtration life compared to a conventional pincushion type cylindrical filter, and further, in order to prevent a decrease in the collection efficiency on the coarse accuracy side, it is excellent in separability. ing. Moreover, there is little drop-out of the fiber, and foaming is not observed in the case of using a nonwoven fabric by a spunbond method or a melt blow method.
[Brief description of the drawings]
FIG. 1 is a perspective view of a cylindrical filter according to the present invention.
FIG. 2 is a diagram for explaining a tongue piece-containing belt-like nonwoven fabric used in the present invention, and is a drawing showing an example in which a tongue piece portion is formed on the belt-like nonwoven fabric side.
FIG. 3 is a view for explaining a tongue-like portion-containing strip-shaped nonwoven fabric used in the present invention, and is a drawing showing an example of a tongue-piece portion formed in the surface of the strip-shaped nonwoven fabric.
4 is a view showing an area of a tongue piece portion shown in FIG. 2;
5 is a drawing showing the area of the tongue piece portion shown in FIG. 3. FIG.
FIG. 6 is an explanatory diagram showing a state in which the strip-shaped non-woven fabric containing a tongue piece is passed through a traverse guide.
[Explanation of symbols]
1 Banded nonwoven fabric containing tongue pieces
2 Notches (including the case where the nonwoven fabric is removed)
3 Tongue pieces
4 Edge of strip-shaped nonwoven fabric
5 Tubular filter
6 Perforated tubular body
7 Convergence of strip-shaped nonwoven fabric containing tongue pieces
8 Thread spacing
9 Spindle
10 Traverse Guide
A Wrapping direction of strip-shaped nonwoven fabric containing tongue piece
B, B 'Traverse guide movement direction
C Spindle rotation direction

Claims

A tubular filter formed by winding a belt-shaped nonwoven fabric having a tongue piece portion, which includes thermoplastic fibers and at least a part of the fiber intersections, around a perforated tubular body.

The cylindrical filter according to claim 1, wherein the strip-shaped nonwoven fabric having a tongue piece is a nonwoven fabric containing at least 30% by weight of thermoplastic fibers.

The cylindrical filter according to claim 1 or 2, wherein the band-shaped nonwoven fabric having a tongue piece is thermocompression bonded with a hot embossing roll.

The cylindrical filter according to any one of claims 1 to 3, wherein at least a part of the fiber intersections of the strip-shaped nonwoven fabric having the tongue piece is thermally bonded.

The cylindrical filter according to any one of claims 1 to 4, wherein an area ratio of the tongue piece portion to the entire area of the belt-shaped nonwoven fabric having the tongue piece portion is 10 to 80%.

The cylindrical filter according to any one of claims 1 to 5, wherein a twist is added to a belt-shaped nonwoven fabric having a tongue piece.

The cylindrical filter according to any one of claims 1 to 6, wherein the porosity of the filtration layer of the cylindrical filter is 65 to 90%.

The cylindrical filter according to any one of claims 1 to 7, wherein the belt-like nonwoven fabric having a tongue piece is a nonwoven fabric made of long fibers.

The thermoplastic fiber which comprises the strip | belt-shaped nonwoven fabric which has a tongue piece part consists of low melting-point resin and high melting-point resin, and the melting | fusing point difference of these both resin is a composite fiber of 10 degreeC or more. Tubular filter.

The cylindrical filter according to any one of claims 1 to 9, wherein a porous material other than a strip-shaped nonwoven fabric having a tongue piece portion on a part of a filtration layer of the cylindrical filter is used.