JP3753522B2 - Melt blown nonwoven fabric and nozzle piece for melt blown nonwoven fabric - Google Patents
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
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Description
【０００１】
【発明の属する技術分野】
本発明は、直径の異なる極細繊維が適度に混合分散した繊維径分布の広いメルトブロー不織布およびその製造用ノズルピースに関する。
【０００２】
【従来の技術】
メルトブロー法による不織布の製造方法は、古くからしられており、例えば、その原理は、Ｕ．Ｓ ＮＡＶＡＬ ＲＥＳＥＡＲＣＨ ＬＡＢＯＲＡＴＯＲＹ（Ｒｅｐｏｒｔ Ｎｏ．５２６５，Ｆｅｂｒｕａｒｙ，１１，１９５９）によって報告されている。さらには、この製造方法を最初に工業化したエクソンケミカル社の特許である特開昭５０−４６９７２号公報、あるいは、報文Ｍｅｌｔ Ｂｌｏｗｉｎｇ−Ａ Ｏｎｅ−Ｓｔｅｐ Ｗｅｂ Ｐｒｏｃｅｓｓ ｆｏｒ ＮｅｗＮｏｎｗｏｖｅｎ Ｐｒｏｄｕｃｔｓ（Ｖｏｌ ５６，Ｎｏ．４ Ａｐｒｉｌ１９７３，Ｔａｐｐｉ Ｊｏｕｒｎａｌ誌）に詳述されている。
この技術によれば、一定の孔径を有するノズルがダイス先端に一定のピッチをおいて多数設置され、そこから吐出された溶融ポリマーが高温のジェット気流中で紡糸され、比較的均一な直径をもつ極細繊維からなる不織布が形成される。
その構成繊維径は、メルトブロー法の製造条件、たとえば支配的因子として、ポリマー吐出温度、吐出量、エアー量などの変更によって、任意に変更できるが、その繊維径は比較的均一であり、従って繊維径の分布は狭いのが特徴である。
【０００３】
このような不織布を液体フィルターなどに応用したとき、その濾過精度は構成繊維径に多くを依存している。たとえば、濾過の精度を上げるためには、繊維径の細い不織布を用い、場合によってはさらに熱カレンダーロールによって圧密して不織布の有効径を小さくして、濾過精度を上げるのが通例である。
しかしながら、このような極細繊維からなる不織布素材をフィルターに用いた場合、微少な粒子を補集できる反面、補集した粒子による目詰まりを短時間に起こしやすく、フィルターとしての寿命が短いという欠点がある。
【０００４】
これを改善するために、異なる径の繊維が分布したメルトブロー不織布を用いる方法が考えられ、その不織布を製造する方法としては、異なる径を持つノズルを設置した２個以上のダイを用いてメルトブロー不織布を得るマルチダイ法や繊維径の異なる複数の不織布を積層させる方法が用いられ、フィルターとしての捕集精度とフィルター寿命をともに向上させる手段が一般に行われている。ここで積層する方法としては、層間に接着剤を用いたり、熱カレンダーロールにて熱圧着することが行われている。
しかしながら、このようなマルチダイ法や積層方法においては、異なる繊維径を有する不織布を別個に製造する必要があること、および熱カレンダーロール工程や接着剤塗布工程などが必要となること、さらには、これらの加工による不織布の変質や使用時の層間剥離などを伴うことがあり、品質保持の観点で課題を抱えている。
【０００５】
【発明が解決しようとする課題】
本発明の目的は、前述の問題点を解決し、高精度で、長寿命のフィルター用に用いることのできる、同時一体的に形成された繊維径分布が広い、単一のメルトブロー不織布およびそのメルトブロー不織布製造用ノズルピースを提供することを課題とする。
【０００６】
【課題を解決するための手段】
本発明者は、かかる課題を解決するために、鋭意研究した結果、特定の範囲の異なる孔径をもつノズル孔を配置したノズルピースを用いることによって、メルトブロー時の紡糸繊維径分布を変え、直径の異なる１〜１０ミクロンの繊維が適度に混合分散した不織布がメルトブロー時において同時一体的に形成され、これによって、構成繊維径分布の広い不織布を得ることが可能となり、繊維径の異なる別個の不織布を積層張り合わせたものと同様の濾過性能を有するフィルター素材を効率良く製造することができることを見出し、本発明を完成した。
【０００７】
すなわち、本発明の第１の発明は、ダイ先端部に一列に穿孔された円形ノズル孔を有するノズルピースにおいて、隣接する孔径Ｄａのノズル孔Ａの間に、ノズル孔Ａより孔径が小さい孔径Ｄｂのノズル孔Ｂのｎ個の列を挿入配置したメルトブロー不織布用ノズルピースを用いて得られる繊維径が１〜１０μｍで、次式で表される繊維径分散比Ｆが２以上である平面的にも立体的にも繊維径分布の広い極細繊維よりなる単一のメルトブロー不織布であり、
繊維径分散比Ｆ＝Ｖ／Ｖ0
（式中、Ｖ0は同一孔径の孔を有するノズルピースより得られた不織布の構成繊維径の不偏分散値であり、Ｖは当該不織布の構成繊維径の不偏分散値である。）本発明の第２の発明は、ダイ先端部に一列に穿孔された円形ノズル孔を有するノズルピースにおいて、隣接する孔径Ｄａのノズル孔Ａの間に、ノズル孔Ａより孔径が小さい孔径Ｄｂのノズル孔Ｂの２〜４個の列を挿入配置したノズルピースであって、ノズル孔Ａの孔径とノズル孔Ｂの孔径の比Ｒ（Ｄａ／Ｄｂ）が１．３〜２．０であるメルトブロー不織布用ノズルピースである。
【０００８】
【発明の実施の形態】
１．ノズルピース
熱可塑性樹脂のメルトブロー法不織布は、通常、第１図に示すような断面図を有するダイを用い、ダイ先端部のノズルピース１に一列に穿孔された多数のノズル孔から吐出された溶融ポリマーがエアスリットからの高温気流中で紡糸され、極細繊維からなる熱可塑性樹脂の不織布を形成して製造されており、この方法によって得られたメルトブロー不織布の繊維径分布は狭いのが特徴である。
【０００９】
本発明のメルトブロー不織布用ノズルピースは、メルトブロー時に、紡糸繊維の径を変え、直径の異なる１〜１０ミクロンの繊維が適度に混合分散した不織布を同時一体的に形成し、得られる不織布の繊維径分布を広げることができるノズルピースである。すなわち、第１図に示すダイのノズルピース部分において、第２図に示すように、その先端部に一列に一定間隔に穿孔された多数の孔径Ｄａの円形ノズル孔Ａの間に、ノズル孔Ａよりも孔径の小さい孔径Ｄｂのノズル孔Ｂのｎ個の列を挿入したノズルピースである。ただし、これらの孔の中心間距離、いわゆるピッチ間隔は隣接する同孔径同士Ａ−ＡおよびＢ−Ｂの間では等しいものとする。上記のノズル孔Ｂの挿入個数ｎは、２〜４の範囲である。ｎが２個未満であると、得られるメルトブロー不織布の繊維径分布は広がらず、ｎが４個を超えるとスムーズな繊維形成が行われない。
【００１０】
また、両ノズル孔Ａ，Ｂの孔径比Ｒ（Ｄａ／Ｄｂ）は、１．３〜２．０の範囲である。孔径比Ｒが１．３未満であると、繊維径分布が広がらず、孔径比Ｒが２．０を超えると孔径の大小差に基づく樹脂の吐出バランスがくずれ、安定した紡糸状態が得られずショットが発生するので好ましくない。
さらに、ノズル孔Ａの孔径Ｄａは、０．３０〜１．００ｍｍであり、ノズル孔Ｂの孔径Ｄｂは、０．２０〜０．８０ｍｍである。Ｄｂが０．２０ｍｍ未満の場合、機械工作上の困難さを伴うため好ましくなく、またＤａが１．００ｍｍを超えると細い繊維が得にくく、また粗大化した繊維が１０ミクロンを超えるため本発明の目的からはずれる。
【００１１】
２．メルトブロー不織布
本発明のメルトブロー不織布は、前記ノズルピースを有したメルトブロー用不織布ダイを用いて製造され、繊維径が１〜１０μｍで、繊維径分散比Ｆが２以上である平面的にも立体的にも繊維径分布の広い単一のメルトブロー不織布である。
一般に、同一孔径ノズルを有するダイから得られるメルトブロー不織布の繊維径分布は、図３（Ａ）に示すような狭い正規分布をもっている。本発明のメルトブロー不織布は、同一孔径のノズルを有するノズルピースの孔の間にそれより小さな孔径の特定数のノズル孔列を挿入配置したノズルピースを用いることによって、従来の狭い繊維径分布を持つメルトブロー不織布に比べて、図３（Ｂ）のような広がった繊維径分布を持つメルトブロー不織布を得ることができる。
【００１２】
すなわち、繊維径分散比Ｆが２以上である平面的にも立体的にも繊維径分布の広い極細繊維よりなる単一のメルトブロー不織布であり、この不織布は、液体フィルターなどに応用したとき、微少な粒子を補集でき、補集した粒子による目詰まりが起こりにくく、濾過の精度の高い、且つ濾過寿命の長い液体フィルターとなる。また、接着剤等を使用しておらず、加工による不織布の変質や使用時の層間剥離などを伴うことがなく、品質保持の観点からも優れた液体フィルターとなる。
【００１３】
本発明のメルトブロー不織布に適する熱可塑性樹脂としては、ポリオレフィン、ポリアミド、ポリアクリルニトリル、ポリエステル、スチレン−ポリオレフィン共重合体、フッソ樹脂、ポリアリーレンスルフィド等が挙げられ、さらに、これらの樹脂をポリマー骨格とする共重合体またはブレンド体も適用できる。これらの樹脂の内、ポリオレフィンであるポリプロピレンが好ましく用いられる。
また、これらの樹脂には必要に応じて、染料、添加剤、変性剤、無機フィラー等を配合することができる。
【００１４】
３．不織布の製造
本発明の繊維径分布の広いメルトブロー不織布は、上記のノズルピースを有するダイを用いて製造されるが、上記熱可塑性樹脂を単軸押出機又は２軸押出機を経て本発明のダイに導入され、孔径の異なるノズルを配置した複数のオリフィスから吐出され、高速空気で延伸されて、１〜５０ｍ／分の速度にて移動しているコンベア上のスクリーンに捕集されメルトブロー不織布を形成する。コンベア速度とダイからの樹脂の吐出量により不織布の目付重量と、厚みが設定される。
【００１５】
【実施例】
本発明を以下の実施例、比較例にて詳細に説明する。なお、評価方法については以下の方法を用いた。
（１）平均繊維径：得られた不織布の繊維径を走査型電子顕微鏡にて１０００倍の写真画像を得、これより無作為に抽出した３０本の繊維径を測定して求めた。
【００１６】
（２）繊維径分散比Ｆ：比較例１の不織布の繊維径のバラツキの尺度として不偏分散値Ｖ0を求め、同じく実施例にて得られた不織布の繊維径の不偏分散値をＶとし、両者の比をとり、Ｆ検定にて（Ｆ＝２．０：Ｆ分布より自由度φ0，φ1＝３０、９７．５％信頼区間から引用）有意差検定を行った。
【００１７】
（３）繊維径分布：繊維径分散比ＦをＦ＝Ｖ／Ｖ0とし、このＦと有意差判定値２．０を超えた場合を分布が広がったと判定した。
【００１８】
（４）ショット：任意に１０ｃｍ角の原反を目視観察し、目視で判定できる大きさのショットの数が３個以上の場合を多いと判断した。
【００１９】
（５）濾過効果：不織布の濾過性能を次の液体フィルター評価装置を用い、微粒子の懸濁液を濾過させたとき、圧力損失が１ｋｇ／ｃｍ2になるまでに流れた総流量（リットル）をもって判定した。
測定装置：ＡＤＶＡＮＴＥＣ社製ＴＳＵ−４７Ｂ型液体フィルター評価装置
微粒子：ＪＩＳ１１種
通液速度：５００ｃｃ／分（一定）
【００２０】
比較例１
メルトフローレート（ＭＦＲ）が４０のポリプロピレン樹脂を下記の押出機、ノズルピース、不織布製造装置、によって加熱溶融し、ダイに導入し、多数に配列したノズルから高温高速の気流中に吹き出し、押し出した樹脂を繊維状にし、これをコンベア上に集積し、繊維同志の自己接着により、平均繊維径５．５μｍ、目付６０ｇ／ｍ2のメルトブロー不織布を形成した。不織布形成時のショットの生成についても観察した。
次に、得られた不織布を液体フィルタとして用いた場合の濾過性能試験を行った。その結果を表１に示す。
【００２１】
不織布製造装置
（１）押出機：池貝鉄工社製単軸押出機で、スクリュー径５０ｍｍ。
（２）ノズルピース：第１図に示すダイ構造において、エアスリット幅ｔ＝０．２０ｍｍ、ノズル先端角θ＝６０度、エアリップ開度ｗ＝０．４ｍｍ、孔径（Ｄａ）＝０．４ｍｍのノズル孔を有し、ノズル孔は１インチあたりに３０孔一直線上に配列し、全長が２５０ｍｍの幅を有する。
（３）コンベア：コンベア上のスクリーンは１〜５０ｍ／分の速度にて移動しつつ、繊維を補足し不織布を形成する。
【００２２】
不織布製造装置運転条件
押し出し機バレル温度 ３２０℃
スクリュ回転数 ４０ｒｐｍ
吐出量 ５ｋｇ／時
ダイ温度 ２９０℃
ダイ−スクリーン距離 ２００ｍｍ
空気温度 ２８０℃
空気流量 ５Ｎｍ3／分
【００２３】
実施例１
比較例１において、ノズルピースとして、孔径Ｄａ＝０．６ｍｍのノズル孔Ａを有し、２個の孔径Ｄｂ＝０．４ｍｍのノズル孔Ｂがノズル孔Ａの間に配列したノズルピースを用いる以外は、比較例１と同様にして、平均繊維径５．６μｍの不織布を得た。
得られた不織布を比較例１と同様の方法で繊維径を測定し、その分布を求めた。また、実施例１で得た不織布の繊維径の分布を比較例のそれと比較するために、比較例１の繊維径のバラツキの尺度として繊維径分散比Ｆを求め、繊維径分布の差を判定した。不織布成形時のショットの数の評価及び得られた不織布の濾過性能について比較例１と同様にして評価を行った。その結果を表１示す。
【００２４】
実施例２〜３、比較例２〜５
比較例１において、ノズルピースとして、孔径Ｄａのノズル孔Ａ及び孔径Ｄｂのノズル孔Ｂ、孔径比Ｒ（Ｄａ／Ｄｂ）、ノズル孔Ｂの個数（ｎ）を表１に示すものを用いる以外は、比較例１と同様にして、不織布を得た。
得られた不織布を比較例１と同様の方法で繊維径を測定し、実施例１と同様の方法で、その分布を求めた。また、比較例１及び実施例１と同様に得られた不織布の性能評価を行った。その結果を表１に示す。
【００２５】
【表１】
表１から明らかなように、同一ノズル孔Ａのみの従来のノズルピースを用いた場合（比較例１）に比較して、ノズル孔径比が本発明の範囲の小さい孔径のノズル孔Ｂが２〜４個挿入されたノズルピースを用いた場合、得られる不織布は繊維径分布が広がり、液体フィルタとしての濾過効率が優れている（実施例１〜３）。一方、ノズル孔径比が１．２と本発明の範囲を下回る孔径Ｄｂのノズル孔Ｂを挿入配置したノズルピースを用いると得られた不織布の繊維径分布は広がらず、液体フィルタとしての濾過効率は劣る（比較例２）。また、ノズル孔Ｂの挿入個数が多くなると、得られた不織布の繊維径分布は広がらず、液体フィルタとしての濾過効率は劣る（比較例３）。さらに、ノズル孔Ｂの挿入個数が少な過ぎると、繊維径分布は広がらず、液体フィルタとしての濾過効率は劣り（比較例４）、ノズル孔径比が大き過ぎると、隣接する孔径の差による樹脂の吐出量の差が大きくなり、溶融紡糸状態のバランスが崩れ、ショットが顕著になり、液体フィルタとして用いることができない（比較例５）。
【００２７】
【発明の効果】
本発明のメルトブロー用ノズルピースを用いて得られたメルトブロー不織布は、メルトブロー時に紡糸繊維の径を変えて、直径の異なる１〜１０ミクロンの繊維が適度に混合分散した不織布が同時一体的に形成された不織布である。これによって、構成繊維径分布の広い不織布を得ることが可能となり、繊維径の異なる別個の不織布を積層張り合わせたものと同様の濾過性能を有するフィルター素材を効率良く製造することができる。
【図面の簡単な説明】
【図１】メルトブローダイの断面図
【図２】メルトブローダイのノズルピースのノズル孔部分図
【図３】メルトブロー不織布の繊維径分布図
【符号の説明】
１ ノズルピース
２ エアリップ
Ａ，Ｂ ノズル孔
ｔ エアスリット
ｗ エアリップ開度
θ ノズル先端角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a melt blown nonwoven fabric having a wide fiber diameter distribution in which ultrafine fibers having different diameters are appropriately mixed and dispersed, and a nozzle piece for manufacturing the melt blown nonwoven fabric.
[0002]
[Prior art]
The manufacturing method of the nonwoven fabric by the melt blow method has been made for a long time. S NAVAL RESEARCH LABORATORY (Report No. 5265, February, 11, 1959). Furthermore, Exxon Chemical Co., Ltd., which is a patent of Exxon Chemical Co., Ltd., which first industrialized this production method, or the report MeltBlowing-A One-Step Web Process for NewNonvenven Products (Vol 56, No. 4). (April 1973, Tapi Journal).
According to this technique, a large number of nozzles having a constant hole diameter are installed at a constant pitch at the die tip, and the molten polymer discharged from the nozzle is spun in a high-temperature jet stream and has a relatively uniform diameter. A nonwoven fabric made of ultrafine fibers is formed.
The constituent fiber diameter can be arbitrarily changed by changing the production conditions of the melt-blowing method, for example, the polymer discharge temperature, the discharge amount, the air amount, etc. as a dominant factor, but the fiber diameter is relatively uniform, so the fiber The diameter distribution is narrow.
[0003]
When such a nonwoven fabric is applied to a liquid filter or the like, the filtration accuracy largely depends on the diameter of the constituent fibers. For example, in order to increase the accuracy of filtration, it is usual to use a non-woven fabric having a thin fiber diameter, and in some cases, further compressing with a heat calender roll to reduce the effective diameter of the non-woven fabric to increase the filtration accuracy.
However, when a non-woven material made of such ultrafine fibers is used for a filter, fine particles can be collected, but clogging due to the collected particles is likely to occur in a short time, and the filter has a short lifetime. is there.
[0004]
In order to improve this, a method using a melt blown nonwoven fabric in which fibers of different diameters are distributed is considered. As a method for producing the nonwoven fabric, a melt blown nonwoven fabric using two or more dies provided with nozzles having different diameters is used. The method of laminating a plurality of non-woven fabrics having different fiber diameters and the multi-die method for obtaining the filter are generally used, and means for improving both the collection accuracy as a filter and the filter life are generally used. As a method of laminating here, an adhesive is used between the layers, or thermocompression bonding is performed with a heat calender roll.
However, in such a multi-die method and a lamination method, it is necessary to separately manufacture nonwoven fabrics having different fiber diameters, and a heat calender roll process and an adhesive application process are required. There is a problem from the viewpoint of maintaining quality, which may be accompanied by alteration of the nonwoven fabric due to the processing of, and delamination during use.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems, and to be used for a high-precision, long-life filter, a single melt blown nonwoven fabric having a wide fiber diameter distribution formed simultaneously and a single melt blow nonwoven fabric and its melt blow It aims at providing the nozzle piece for nonwoven fabric manufacture.
[0006]
[Means for Solving the Problems]
As a result of earnest research to solve such problems, the present inventor changed the spinning fiber diameter distribution at the time of melt blowing by using a nozzle piece having nozzle holes having different hole diameters in a specific range, Non-woven fabrics in which fibers of different 1 to 10 microns are appropriately mixed and dispersed are formed integrally at the time of meltblowing, thereby making it possible to obtain non-woven fabrics having a wide distribution of constituent fiber diameters. The inventors have found that a filter material having the same filtration performance as that obtained by laminating can be efficiently produced, and the present invention has been completed.
[0007]
That is, according to the first aspect of the present invention, in a nozzle piece having circular nozzle holes perforated in a line at the tip of the die, a hole diameter Db having a smaller hole diameter than the nozzle hole A is provided between the nozzle holes A having the adjacent hole diameter Da. The fiber diameter obtained using a nozzle piece for melt blown nonwoven fabric in which n rows of nozzle holes B are inserted and arranged is 1 to 10 μm, and the fiber diameter dispersion ratio F represented by the following formula is 2 or more in plan view Is a single melt blown non-woven fabric consisting of ultrafine fibers with a wide fiber diameter distribution.
Fiber diameter dispersion ratio F = V / V 0
(In the formula, V 0 is an unbiased dispersion value of the constituent fiber diameter of the nonwoven fabric obtained from the nozzle piece having holes of the same pore diameter, and V is an unbiased dispersion value of the constituent fiber diameter of the nonwoven fabric.) In a second aspect of the present invention, in a nozzle piece having circular nozzle holes perforated in a line at the tip of the die, a nozzle hole B having a hole diameter Db smaller than the nozzle hole A is provided between adjacent nozzle holes A having a hole diameter Da. Nozzle piece for melt blown nonwoven fabric in which 2 to 4 rows are inserted and arranged, and the ratio R (Da / Db) of the hole diameter of nozzle hole A to the hole diameter of nozzle hole B is 1.3 to 2.0 It is.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
1. The melt blown nonwoven fabric of nozzle piece thermoplastic resin is usually a die having a cross-sectional view as shown in FIG. 1, and melted from a large number of nozzle holes perforated in the nozzle piece 1 at the tip of the die. A polymer is spun in a high-temperature air stream from an air slit to produce a thermoplastic resin nonwoven fabric composed of ultrafine fibers, and the melt blown nonwoven fabric obtained by this method is characterized by a narrow fiber diameter distribution. .
[0009]
The nozzle piece for the melt blown nonwoven fabric of the present invention changes the diameter of the spun fiber at the time of melt blowing, and simultaneously forms a nonwoven fabric in which fibers of 1 to 10 microns having different diameters are appropriately mixed and dispersed, and the fiber diameter of the resulting nonwoven fabric. It is a nozzle piece that can widen the distribution. That is, in the nozzle piece portion of the die shown in FIG. 1, as shown in FIG. 2, the nozzle holes A are arranged between the circular nozzle holes A having a large number of hole diameters Da perforated in a line at the front end portion. This is a nozzle piece in which n rows of nozzle holes B having a hole diameter Db having a smaller hole diameter are inserted. However, the center-to-center distance of these holes, the so-called pitch interval, is assumed to be equal between adjacent hole diameters AA and BB. The insertion number n of the nozzle holes B is in the range of 2-4. When n is less than 2, the fiber diameter distribution of the resulting meltblown nonwoven fabric does not widen, and when n exceeds 4, smooth fiber formation is not performed.
[0010]
Moreover, the hole diameter ratio R (Da / Db) of both the nozzle holes A and B is in the range of 1.3 to 2.0. When the pore diameter ratio R is less than 1.3, the fiber diameter distribution does not widen, and when the pore diameter ratio R exceeds 2.0, the resin discharge balance based on the size difference of the pore diameter is lost, and a stable spinning state cannot be obtained. Since a shot is generated, it is not preferable.
Furthermore, the hole diameter Da of the nozzle hole A is 0.30 to 1.00 mm, and the hole diameter Db of the nozzle hole B is 0.20 to 0.80 mm. When Db is less than 0.20 mm, it is not preferable because it involves difficulty in machining, and when Da exceeds 1.00 mm, it is difficult to obtain thin fibers, and coarse fibers exceed 10 microns. Deviate from purpose.
[0011]
2. Melt blown nonwoven fabric The melt blown nonwoven fabric of the present invention is manufactured using a melt blown nonwoven fabric die having the nozzle piece, and has a fiber diameter of 1 to 10 μm and a fiber diameter dispersion ratio F of 2 or more in three dimensions. Is a single melt blown nonwoven fabric with a wide fiber diameter distribution.
In general, the fiber diameter distribution of a melt blown nonwoven fabric obtained from a die having the same hole diameter nozzle has a narrow normal distribution as shown in FIG. The melt blown nonwoven fabric of the present invention has a conventional narrow fiber diameter distribution by using a nozzle piece in which a specific number of nozzle hole rows having a smaller hole diameter are inserted between holes of nozzle pieces having nozzles having the same hole diameter. Compared to the melt blown nonwoven fabric, a melt blown nonwoven fabric having a broader fiber diameter distribution as shown in FIG. 3B can be obtained.
[0012]
That is, it is a single meltblown nonwoven fabric made of ultrafine fibers having a fiber diameter dispersion ratio F of 2 or more and having a wide fiber diameter distribution both in a plane and in three dimensions, and this nonwoven fabric is very small when applied to a liquid filter or the like. Therefore, it is difficult to cause clogging by the collected particles, and the liquid filter has a high filtration accuracy and a long filtration life. Further, no adhesive or the like is used, and there is no alteration of the nonwoven fabric due to processing or delamination during use, and the liquid filter is excellent from the viewpoint of maintaining quality.
[0013]
Examples of the thermoplastic resin suitable for the melt blown nonwoven fabric of the present invention include polyolefin, polyamide, polyacrylonitrile, polyester, styrene-polyolefin copolymer, fluorine resin, polyarylene sulfide, and the like. Copolymers or blends can also be applied. Of these resins, polypropylene, which is polyolefin, is preferably used.
Moreover, dye, an additive, a modifier, an inorganic filler, etc. can be mix | blended with these resin as needed.
[0014]
3. Production of Nonwoven Fabric The melt blown nonwoven fabric having a wide fiber diameter distribution according to the present invention is produced using a die having the nozzle piece described above. The thermoplastic resin is passed through a single screw extruder or a twin screw extruder and the die according to the present invention. , Discharged from multiple orifices with nozzles with different hole diameters, stretched with high-speed air, and collected on a screen on a conveyor moving at a speed of 1 to 50 m / min to form a melt blown nonwoven fabric To do. The fabric weight and thickness of the nonwoven fabric are set according to the conveyor speed and the amount of resin discharged from the die.
[0015]
【Example】
The present invention will be described in detail in the following examples and comparative examples. In addition, the following method was used about the evaluation method.
(1) Average fiber diameter: The fiber diameter of the obtained nonwoven fabric was obtained by obtaining a 1000-fold photographic image with a scanning electron microscope, and measuring 30 fiber diameters randomly extracted from this.
[0016]
(2) Fiber diameter dispersion ratio F: The unbiased dispersion value V 0 was determined as a measure of the fiber diameter variation of the nonwoven fabric of Comparative Example 1, and the fiber diameter unbiased dispersion value of the nonwoven fabric obtained in the same example as V. The ratio of the two was taken, and the F test (F = 2.0: degrees of freedom φ 0 , φ 1 = 30, quoted from 97.5% confidence interval from F distribution) was carried out a significant difference test.
[0017]
(3) Fiber diameter distribution: The fiber diameter dispersion ratio F was set to F = V / V 0, and the case where this F and the significant difference determination value 2.0 was exceeded was determined to be spread.
[0018]
(4) Shots: A 10 cm square original fabric was arbitrarily observed visually, and it was determined that the number of shots having a size that could be visually determined was 3 or more.
[0019]
(5) Filtration effect: When the filtration performance of the nonwoven fabric was filtered using the following liquid filter evaluation device, and the fine particle suspension was filtered, the total flow rate (liter) that flowed until the pressure loss reached 1 kg / cm 2 Judged.
Measuring device: TSU-47B type liquid filter evaluation device manufactured by ADVANTEC Co., Ltd. Fine particles: JIS 11 species flow rate: 500 cc / min (constant)
[0020]
Comparative Example 1
A polypropylene resin having a melt flow rate (MFR) of 40 was heated and melted by the following extruder, nozzle piece, and non-woven fabric manufacturing apparatus, introduced into a die, and blown out into a high-temperature and high-speed air stream from a number of arranged nozzles. The resin was made into a fiber, and this was accumulated on a conveyor, and a melt blown nonwoven fabric having an average fiber diameter of 5.5 μm and a basis weight of 60 g / m 2 was formed by self-adhesion of the fibers. The generation of shots during the formation of the nonwoven fabric was also observed.
Next, the filtration performance test at the time of using the obtained nonwoven fabric as a liquid filter was done. The results are shown in Table 1.
[0021]
Nonwoven fabric production apparatus (1) Extruder: A single screw extruder manufactured by Ikekai Tekko Co., Ltd., screw diameter 50 mm.
(2) Nozzle piece: In the die structure shown in FIG. 1, air slit width t = 0.20 mm, nozzle tip angle θ = 60 degrees, air lip opening w = 0.4 mm, hole diameter (Da) = 0.4 mm The nozzle holes are arranged on a straight line of 30 holes per inch and have a total length of 250 mm.
(3) Conveyor: The screen on the conveyor moves at a speed of 1 to 50 m / min while capturing fibers to form a nonwoven fabric.
[0022]
Nonwoven fabric manufacturing equipment operating conditions Barrel temperature of extruder 320 ° C
Screw rotation speed 40rpm
Discharge rate 5kg / hour Die temperature 290 ° C
Die-screen distance 200mm
Air temperature 280 ℃
Air flow rate 5Nm 3 / min [0023]
Example 1
In Comparative Example 1, a nozzle piece having a nozzle hole A having a hole diameter Da = 0.6 mm and two nozzle holes B having a hole diameter Db = 0.4 mm arranged between the nozzle holes A is used as the nozzle piece. Produced a nonwoven fabric having an average fiber diameter of 5.6 μm in the same manner as in Comparative Example 1.
The fiber diameter of the obtained nonwoven fabric was measured by the same method as in Comparative Example 1, and the distribution was obtained. Further, in order to compare the fiber diameter distribution of the nonwoven fabric obtained in Example 1 with that of the comparative example, the fiber diameter dispersion ratio F is obtained as a measure of the fiber diameter variation of Comparative Example 1, and the difference in the fiber diameter distribution is determined. did. The evaluation of the number of shots at the time of forming the nonwoven fabric and the filtration performance of the obtained nonwoven fabric were evaluated in the same manner as in Comparative Example 1. The results are shown in Table 1.
[0024]
Examples 2-3 and Comparative Examples 2-5
In Comparative Example 1, a nozzle piece other than the nozzle piece A having the hole diameter Da, the nozzle hole B having the hole diameter Db, the hole diameter ratio R (Da / Db), and the number (n) of the nozzle holes B shown in Table 1 is used. In the same manner as in Comparative Example 1, a nonwoven fabric was obtained.
The fiber diameter of the obtained nonwoven fabric was measured by the same method as in Comparative Example 1, and the distribution was obtained by the same method as in Example 1. Moreover, the performance evaluation of the nonwoven fabric obtained similarly to the comparative example 1 and Example 1 was performed. The results are shown in Table 1.
[0025]
[Table 1]
As is clear from Table 1, compared with the case where the conventional nozzle piece having only the same nozzle hole A is used (Comparative Example 1), the nozzle hole B having a small nozzle diameter ratio in the range of the present invention is 2 to 2. When four nozzle pieces inserted are used, the resulting nonwoven fabric has a wide fiber diameter distribution and excellent filtration efficiency as a liquid filter (Examples 1 to 3). On the other hand, when a nozzle piece having a nozzle hole diameter ratio of 1.2, which is lower than the range of the present invention, is inserted and arranged, the fiber diameter distribution of the obtained nonwoven fabric is not widened, and the filtration efficiency as a liquid filter is Inferior (Comparative Example 2). Moreover, when the insertion number of the nozzle holes B increases, the fiber diameter distribution of the obtained nonwoven fabric does not widen, and the filtration efficiency as a liquid filter is inferior (Comparative Example 3). Furthermore, if the number of inserted nozzle holes B is too small, the fiber diameter distribution is not widened, and the filtration efficiency as a liquid filter is inferior (Comparative Example 4). If the nozzle hole diameter ratio is too large, the resin due to the difference in adjacent hole diameters. The difference in the discharge amount becomes large, the balance of the melt spinning state is lost, the shot becomes remarkable, and it cannot be used as a liquid filter (Comparative Example 5).
[0027]
【The invention's effect】
The melt-blown nonwoven fabric obtained by using the melt-blowing nozzle piece of the present invention is formed by simultaneously and integrally forming a nonwoven fabric in which fibers of 1 to 10 microns having different diameters are appropriately mixed and dispersed by changing the diameter of the spun fiber during melt blowing. Non-woven fabric. This makes it possible to obtain a non-woven fabric having a wide distribution of constituent fiber diameters, and to efficiently produce a filter material having the same filtration performance as that obtained by laminating and laminating separate non-woven fabrics having different fiber diameters.
[Brief description of the drawings]
1 is a cross-sectional view of a melt blow die, FIG. 2 is a partial view of a nozzle hole of a nozzle piece of a melt blow die, and FIG. 3 is a fiber diameter distribution diagram of a melt blow nonwoven fabric.
1 Nozzle piece 2 Air lip A, B Nozzle hole t Air slit w Air lip opening θ Nozzle tip angle
Claims (2)
繊維径分散比Ｆ＝Ｖ／Ｖ0
（式中、Ｖ0は同一孔径の孔を有するノズルピースより得られた不織布の構成繊維径の不偏分散値であり、Ｖは当該不織布の構成繊維径の不偏分散値である。）In a nozzle piece having circular nozzle holes perforated in a line at the tip of the die, n rows of nozzle holes B having a diameter Db smaller than the nozzle holes A are inserted between adjacent nozzle holes A having a diameter Da. The fiber diameter obtained using the arranged nozzle piece for melt blown nonwoven fabric is 1 to 10 μm, and the fiber diameter dispersion ratio F represented by the following formula is 2 or more. A single meltblown nonwoven fabric made of fibers.
Fiber diameter dispersion ratio F = V / V 0
(In the formula, V 0 is an unbiased dispersion value of the constituent fiber diameter of the nonwoven fabric obtained from the nozzle piece having the same hole diameter, and V is an unbiased dispersion value of the constituent fiber diameter of the nonwoven fabric.)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31261797A JP3753522B2 (en) | 1997-10-29 | 1997-10-29 | Melt blown nonwoven fabric and nozzle piece for melt blown nonwoven fabric |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31261797A JP3753522B2 (en) | 1997-10-29 | 1997-10-29 | Melt blown nonwoven fabric and nozzle piece for melt blown nonwoven fabric |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11131353A JPH11131353A (en) | 1999-05-18 |
| JP3753522B2 true JP3753522B2 (en) | 2006-03-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP31261797A Expired - Lifetime JP3753522B2 (en) | 1997-10-29 | 1997-10-29 | Melt blown nonwoven fabric and nozzle piece for melt blown nonwoven fabric |
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| JP (1) | JP3753522B2 (en) |
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