JP3705420B2 - Sound absorbing material - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、軽量で厚みが薄いにも関わらず吸音性および制振特性にすぐれた吸音材に関する。さらに詳しくは、広い温度域での成型時の絞り部での変形が大きくても千切れることのない成形性の良い吸音材に関する。
【０００２】
【従来の技術】
自動車や建築用途などの吸音材として短繊維不織布が広く用いられている。吸音性能を高くするために、繊維径を細くして空気の通過抵抗を大きくしたり、目付を大きくするなどの方法が採られてきた。その結果、高い吸音性能を求められる場合には、繊維径が１５ミクロン程度と比較的細い繊維を用い、目付が５００〜５０００ｇ／ｃｍ2の厚くて重い短繊維不織布が用いられている。
極細繊維を含む不織布は優れた吸音特性やフィルター性、遮蔽性などのすぐれた特性があり多くの用途に利用されてきたが、強度が弱かったり、形態安定性が悪いなどの問題があり、その改善のために別の不織布と積層複合化して用いられてきた。この際に不織布を積層一体化する方法として、スプレーや転写などでバインダーとなる樹脂あるいは熱融着繊維などを用いていた。しかしながら、これらの方法では、乾燥あるいは樹脂の融解接着の目的で熱処理を行うことが必要であり、排気ガスにようる環境汚染の問題や省エネルギーの観点からあまり好ましい物でない。また、バインダー樹脂が不織布間の界面で皮膜を形成し、吸音性が低下するなどの問題もある。
【０００３】
一方、極細繊維不織布と長繊維不織布を積層一体化する方法は通称Ｓ／Ｍ／Ｓなどの名前で知られる、スパンボンド不織布の間に極細繊維であるメルトブローン不織布を積層して熱エンボス法で接合する方法が知られている。しかしながら、これらの不織布は、ボリューム感に欠け、硬い風合いとなっており用途が制限されてしまうという問題点がある。
また、コフォームと呼ばれる、メルトブローン不織布の内部に２０〜３０ミクロン前後の短繊維を吹き込んで複合化した不織布も商品化されているが、形態安定性や成形加工性が悪い点が問題である。
自動車内装材や電気製品などに組み込まれる吸音材は、立体成型される事が少なくないが、従来の吸音材では、成型時の絞りが深く、絞り部での変形が大きいと、変形が追随できなくて千切れるという問題がある。
また、吸音性能を上げるために極細の繊維を使うと、比表面積が増加するために燃焼し易くなるという問題もある。特に、極細繊維がメルトブロー法によって作られた物である場合には、ポリプロピレンが一般的であり、素材の観点からも燃焼し易く、モーターなどの発熱体に接触する用途では安全上の問題が考えられる。
【０００４】
【発明が解決しようとする課題】
本発明は、吸音性能が高く、薄くて軽量で形態安定性の良い吸音材を、安価に提供することを目的とする。特に、自動車関連では、燃費向上や快適性改善のため、軽量で優れた吸音材が要求されており、その要望に応える事も目的とする。成型時の絞り部での変形が大きくても千切れることのない成形性の良い吸音材に関する。また、難燃性の高い吸音材を提供することをも目的とする。
【０００５】
【課題を解決するための手段】
本発明は、かかる問題を解決するために以下の手段をとる。第一の発明は、繊維径が６ミクロン以下の極細エラストマー繊維を含む目付が２０〜２００ｇ／ｍ2の不織布（Ａ）と、目付が５０〜２０００ｇ／ｍ2の不織布（Ｂ）とが積層一体化され、かつ前記の不織布（Ａ）の外側に短繊維のループを有してなり、２５℃における破断伸度が２５％以上であることを特徴とする吸音材である。
【０００６】
第二の発明は、前記の不織布（Ｂ）を構成する繊維の繊維長が５０〜１５０ｍｍの短繊維よりなり、該不織布（Ｂ）と前記の不織布（Ａ）とがニードルパンチ法により積層一体化されていることを特徴とする第一の発明に記載の吸音材である。
【０００７】
第三の発明は、前記の不織布（Ｂ）がポリエステルにより構成されていることを特徴とする請求項１または２に記載の吸音材である。
【０００８】
第四の発明は、第一の発明から第三の発明のいずれかの吸音材の前記の不織布（Ａ）の側の片面に、２５℃での伸度が２５％以上である長繊維不織布が積層されていることを特徴とする吸音材である。
【０００９】
第五の発明は、前記の長繊維不織布が難燃ポリエステルにより構成されていることを特徴とする第四の発明に記載の吸音材である。
【００１０】
【発明の実施の形態】
以下に本発明を詳細に説明する。
本発明に用いられる不織布は、少なくとも２種以上の不織布が接合一体化されていることが必要である。通気性などをコントロールするために極細繊維を含む不織布層にフィルムなどを積層する事も望ましい形態のひとつである。また、織布や織物と複合化するのも使用形態により好ましい。さらに、該複合不織布の外側に色や模様のついた意匠性のある表層不織布を貼り付けても良く、車両内装材や建築材の防音材として好適に用いることが可能である。
【００１１】
本発明における繊維径が６ミクロン以下の極細繊維を含む不織布（Ａ）は、極細繊維を重量で１０％以上含有されていることが好ましい。不織布全体が極細繊維のみで構成されていてもよいが、含有率が小さすぎると極細繊維特性による効果が得られにくく好ましくない。極細繊維の繊維径は５ミクロン以下が好ましく、特に好ましくは、０．５〜４ミクロン以下であり、最も好ましくは１．５〜３ミクロン前後である。
【００１２】
極細繊維の製造法は特に限定されないが、繊維のランダム配列が可能で生産コストの安いメルトブロー法により得られる不織布が特に好ましい。メルトブローン不織布は強度が弱いので、スパンボンド不織布など補強用不織布と接合した不織布を用いたり、積層工程で同時に３層以上の不織布を積層するのも好ましい。この際、耐摩耗性にすぐれたスパンボンド不織布が使用時に表層側にくるように設置することが好ましい。メルトブロー不織布とスパンボンド不織布のエンボス加工積層不織布はＳ／Ｍ／ＳやＳ／Ｍなどの名称で呼ばれ市販されておりこれらを用いるのも好ましい（Ｓはスパンボンド不織布を、Ｍはメルトブロー不織布を表す）。
【００１３】
また、分割繊維あるいは海島型繊維を用いて得られる極細繊維を用いるのも好ましい形態の一つである。分割繊維は予め分割しておいたものを使用しても良いし、積層加工の際に分割を同時に行っても良い。
【００１４】
極細繊維を含む不織布（Ａ）は、目付が２０〜２００ｇ／ｍ2である。目付が、２０ｇ／ｍ2より小さくなると、極細繊維の持つ吸音効果があまり期待できず好ましくない。一方、目付が２００ｇ／ｍ2を超えると、短繊維不織布との複合化する際に皺が入ったり、接合力が弱いという問題が生じる場合がある。また、目付を大きくしすぎても目的とする吸音性などの改善効果があまり変わらず、コスト削減や軽量化などの観点からあまり好ましくない。
【００１５】
極細繊維を含む不織布（Ａ）を構成する素材としては、伸長回復性の高いエラストマー繊維が深絞り成形時の変形追随性などの観点から好ましく、極細繊維に積層される短繊維不織布と類似の素材であることがリサイクルしやすく、より好ましい。一方、複数の素材よりなる繊維を混合しても問題はない。
【００１６】
メルトブロー法により作られる極細繊維を用いる場合は、繊維が長繊維であり切断面がほとんどないエラストマーを用いることが好ましい。極細繊維不織布をニードルパンチ法により他の不織布と積層する際にニードルにより孔上の跡があいてしまって、その孔を空気がチャンネリングして吹き漏れてしまい吸音率が低下するという問題が生じることがあるが、エラストマーであれば変形して元に戻るため、孔のサイズが小さく、吸音率がほとんど低下することがない。発明者らの検討の範囲では、突き刺し密度が１００カ所／ｃｍ2以上では、非エラストマーよりなる極細繊維を用いた場合では吸音性能が著しく低下したのに対して、エラストマーの場合はほとんど性能低下がなく、突き刺し密度を高くすることで積層体の剥離強度を高くすることが可能となり形態安定性を高くすることが可能あった。
【００１７】
次に、極細繊維を含む不織布に積層される不織布（Ｂ）は、繊維径が７〜４０ミクロンが好ましく、より好ましくは７〜２０ミクロンである。繊維径が７ミクロンより細いことは直接大きな問題を引き起こす訳ではないが、カード機よりの紡出性などの生産性の点であまり好ましくない。また、繊維径が７ミクロンより大幅に小さいと、本発明による積層効果が小さくなるので、極細繊維よりも太いことが好ましい。また、不織布が毛羽立ちやすいなど別の問題を生じる場合がある。一方、繊維径が４０ミクロンより太いと、吸音性能に対する寄与が小さくなりあまり好ましくない。
【００１８】
本発明において、短繊維の不織布（Ｂ）を極細繊維を含む不織布と積層するのは、極細繊維を含む不織布がへたり易く形態安定性が低い、毛羽立ち易い、嵩高性の維持に問題を生じやすいなどの問題点を改善するため及び高いクッション性、制振性を得るなどの目的で実施される。また、吸音材は一般的に厚みが大きいほど高い性能を得ることが可能と考えられ、厚みをコントロールする目的でも積層を行う。吸音性能向上に貢献する細い繊維と形態安定性改善に貢献する太い繊維とを適当な割合で混合することで、吸音性能が高く、かつ形態安定性のよい吸音材を設計することが可能である。
【００１９】
本発明における不織布（Ｂ）は、目付が５０〜２０００ｇ／ｍ2の短繊維不織布である。目付が５０ｇ／ｍ2より小さいと積層効果が小さく、不織布の嵩高性や柔らかい風合いの点であまり好ましくない。一方、２０００ｇ／ｍ2より大きい目付であると、厚みが大きくなりすぎてスペースをとったり、重さが重くなるため好ましくない。
【００２０】
本発明における不織布（Ｂ）が短繊維の場合は、繊維長さは３８〜１５０ｍｍが好ましく、特に好ましくは５０〜１５０ｍｍである。本発明者らの検討の範囲では、繊維長が長いほど優れた吸音率を示した。ただし、繊維長が長すぎるとカードからの紡出性が悪くなり好ましくなかった。短繊維は単一成分でも良いが、２種類以上の混合物や複数成分の複合繊維でも良い。不織布の堅さを調整するために重量分率で３０％程度以下であればさらに太い繊維を混合しても特性はあまり変化しない。太い繊維が多すぎると不織布風合いが硬くなりすぎるなどの問題を生じやすくあまり好ましくない。融点の異なる熱融着性繊維を用いることも寸法安定性を改善する観点から好ましい。短繊維不織布の重量ベースの充填密度は、嵩高性の観点から０．００５〜０．３ｇ／ｃｍ3であることが好ましい。充填密度が小さすぎると形態安定性が悪くなりあまり好ましくない。充填密度が０．３ｇ／ｃｍ3より大きくなると吸音性は悪くなる傾向にあり、本発明の目的を満足することが難しくなる。
【００２１】
不織布の積層一体化方法はニードルパンチ法により一体化する事が好ましい。ニードルパンチ法は不織布加工方法として一般的に実施されており、詳細は日本繊維機械学会不織布研究会編集の「不織布の基礎と応用」などで詳細に解説されている。このニードルパンチ法を用いて不織布を複合化することは公知であるが、極細で目が均一化された不織布と繊維が比較的太い嵩高の短繊維不織布をニードルパンチ機で複合化すると極細繊維不織布に穴が開いて、吸音性能やフィルター性能などが低下して極細繊維特性が得にくいと考えられていたためか、発明者の知る限りでは、市場にその商品を見つけることができない。
【００２２】
ニードルパンチ加工を行う際には、３８番手より細いニードル（針）を用いることが好ましく、特に好ましくは４０〜４２番手である。ニードルは、短繊維不織布側から入り、極細繊維を含む不織布の外側に短繊維のループを生じさせる。
【００２３】
極細繊維を含む不織布単独では、繊維が他の物に引っかかったり、それにより切断されたりして毛羽立ちやすいが、本発明の積層不織布では、短繊維のループが極細繊維を含む不織布の表面毛羽立ちを防止したり、クッション層になって、極細繊維不織布層にかかる外力を緩和することで破壊の防止に役立つことが判明した。また、伸度が２５％より高い別の不織布やフィルムなどと積層する際に、該ループと積層相手の第３の素材を接着することで、曲げや引っ張りなどの外力がかかったときに極細繊維を含む不織布の破壊されるのを防止することが可能となることも判明した。
【００２４】
適切なループの大きさを形成するために、ニードルパンチの針深度は１５ｍｍ以下であることが好ましい。それ以上では、極細繊維不織布を針および短繊維が貫通するときの衝撃で不織布が破れたり、貫通した後の針穴が大きくなりすぎることが多くなりあまり好ましくない。針深度は、ニードルのバーブの位置にもよるが５ｍｍ以上であることが、不織布の交絡を増やして剥離を防止する上で好ましい。刺孔密度は３０〜２００本／ｃｍ2であることが好ましい。刺孔密度が３０本／ｃｍ2より小さいと不織布の剥離の問題が生じやすく、２５０本／ｃｍ2より大きいと刺孔による開口総面積が大きすぎたり、極細繊維を含む不織布の破れや破壊を生じやすくあまり好ましくない。
【００２５】
積層された吸音材の破断伸度は２５％以上あることが必要であり、好ましくは５０％以上、特に好ましくは１００％以上である。２５％未満の破断伸度の不織布は、成型時の変形に追随できず極細繊維層などで破壊が起こることにより吸音率が著しく低下してしまうために好ましくない。また、加工工程でも変形性があるので応力のコントロール不良などで切断されるなどの問題を回避することが容易となる。成形温度は室温から２００℃前後での加工が考えられるが、本発明の要件を充足していれば問題となることはほとんどない。
【００２６】
吸音材の毛羽防止や形態安定性改善などの目的に、第一から第三に記載の吸音材に積層する相手として特に好適であるのは、繊維径が５〜２０ミクロンで目付が２０〜２５０ｇ／ｍ2の長繊維不織布である。該長繊維不織布の繊維径が５ミクロン未満であると形態安定性などの改善効果が小さく好ましくない。繊維径が２０ミクロンを超えると不織布の斑が目立ちあまり好ましくない。目付に関しては、２０ｇ／ｍ2未満では地合の斑が目立ち好ましくなく、ニードルパンチで積層しても繊維の絡み点が少ないために簡単に剥離してしまう問題を生じる。一方、目付が２５０ｇ／ｍ2を超えると軽量化を目的とした本発明の趣旨と合致せず好ましくない。
【００２７】
積層される不織布の表面には、色付けをしたり模様をプリントして意匠性を持たせることが好ましい。これにより、建築構造物の吸音材や自動車内装材に用いられる吸音材として視覚的に周囲と違和感なく調和させることが可能となる。繊維の素材としては、伸度が２５％以上あれば特に限定されないが、熱可塑性エラストマーや複屈折率が０．０８より小さいポリエステル系繊維が特に好ましい。
【００２８】
貼り合わせる長繊維不織布は難燃タイプの物が好ましい。難燃化するにはハロゲンを含まない、リン系の難燃剤を塗布したり難燃成分を共重合した素材を使用することが好ましい。他の成分が燃えやすい物であっても、表層に難燃層がくることで通常の難燃基準に合格することが比較的容易に達成できる。
【００２９】
【実施例】
以下に本発明を実施例をあげて説明するが本発明は何らこれらに限定されるものではない。実施例における測定及び評価方法は以下の方法によった。
【００３０】
（平均繊維径）：走査型電子顕微鏡写真で、繊維側面を２０本以上測定して、その平均値から計測した。極細繊維不織布がメルトブロー法の場合は、繊維径のバラツキが大きいため１００本以上を測定して平均値を採用した。
【００３１】
（目付および充填密度）：不織布を２０ｃｍ角に切り出してその重量を測定した値を１ｍ2あたりに換算して目付とした。充填密度は、不織布の目付を２０ｇ／ｃｍ2の荷重下での厚みで割った値を求めて、ｇ／ｃｍ3に単位換算して求めた。
【００３２】
（耐剥離性）：複合した不織布を手で９０度前後折り曲げる動作を２０回繰り返して、剥離が生じるかどうかを目視で評価した。
【００３３】
（破断伸度）：不織布を長さ２０ｃｍ幅５ｃｍの矩形に切り出した。室温２５℃下で、試長１０ｃｍ、クロスヘッド１０ｃｍ／分で低速伸長引っ張り測定をした場合の破断伸度％を求めた。
【００３４】
（吸音率）：ＪＩＳ Ａ−１４０５に従って、垂直入射法吸音率％を求めた。代表値として１０００Ｈｚと２０００Ｈｚの値の平均値を用いた。
【００３５】
【実施例１】
平均繊維径３ミクロン、目付１００ｇ／ｍ2のポリエステルエラストマー（東洋紡績社製ペルプレンＰタイプ）製メルトブローン不織布の上に、平均繊維径１４ミクロン、繊維長５１ｍｍ、捲縮数12個／インチの短繊維よりなる目付２５０ｇ／ｍ2、充填密度０．０６ｇ／ｃｍ3のポリエチレンテレフタレート製ニードルパンチ不織布を重ねて、４０番手のニードルを用いて、刺孔密度５０本／ｃｍ2針深度１０ｍｍでニードルパンチ積層加工を実施した。吸音材を２０回程度折り曲げても剥離の問題は生じず、吸音率も７２％と高く良好であった。不織布の破断伸度は１８０％と大きいために、１００℃で最大絞り深さが約５０％の成形でも問題なく成形できた。
【００３６】
【実施例２】
実施例１において、メルトブローン不織布層側に平均繊維径１４ミクロン、目付２０ｇ／ｍ2の東洋紡績社製難燃ポリエステルスパンボンド不織布（ハイム）をニードルパンチ法の積層時に一緒に積層した。作成した不織布を２０回程度折り曲げても剥離の問題は生じず、吸音率も７０％と高く良好であった。表面を指でこすっても全く毛羽立たず形態安定性に非常に優れていた。不織布の破断伸度は２７％であった。１００℃の成形も可能ではあったが絞り部の外観をより良くするため成形温度を１５０℃まで上げた。最大成形絞り深さが約５０％の成形でも全く問題なく成形できた。
【００３７】
【比較例１】
平均繊維径３ミクロン、目付１５ｇ／ｍ2のポリプロピレン製メルトブローン不織布以外は実施例１と同じ条件で積層不織布を作成した。吸音率を測定したが、６５％と良好であった。不織布の破断伸度は１５％であり、１００℃で最大絞り深さが約５０％の成形を行ったところ、メルトブロー不織布が針穴近傍で破れが発生しており問題であった。温度を１５０℃まで上げると成形深絞り部でメルトブローン不織布がフィルム化しており、厚みが薄くなりすぎて外観上問題であった。
【００３８】
【比較例２】
平均繊維径１４ミクロン、繊維長５１ｍｍ、捲縮数12個／インチの短繊維不織布よりなる目付５００ｇ／ｍ2のポリエチレンテレフタレート製短繊維を４０番手のニードルを用いて、表と裏の両方からそれぞれ刺孔密度３０本／ｃｍ2、針深度１０ｍｍでニードルパンチ加工して、充填密度０．０５ｇ／ｃｍ3の不織布を得た。該不織布は、実施例１に比べて目付が高いにもかかわらず、吸音率を測定したところ２１％と低く問題であった。
【００３９】
【発明の効果】
本発明の吸音材は、吸音性能が高く、薄くて軽量で形態安定性の良い吸音材であり、かつ良好な成型性を示す。特に、自動車用途で燃費向上や快適性改善のため、軽量で優れた成形性の吸音材として利用できる。その他産業上の広い用途で吸音材として好適に使用できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sound-absorbing material that is excellent in sound-absorbing properties and vibration-damping properties despite being lightweight and thin. More specifically, the present invention relates to a sound-absorbing material having good formability that does not break even if the deformation at the throttle portion during molding in a wide temperature range is large.
[0002]
[Prior art]
Short fiber nonwoven fabrics are widely used as sound absorbing materials for automobiles and construction applications. In order to increase the sound absorption performance, methods such as reducing the fiber diameter to increase the air passage resistance and increasing the basis weight have been adopted. As a result, when high sound absorption performance is required, a relatively thin fiber having a fiber diameter of about 15 microns is used, and a thick and heavy short fiber nonwoven fabric having a basis weight of 500 to 5000 g / cm 2 is used.
Non-woven fabrics containing ultrafine fibers have excellent properties such as sound absorbing properties, filter properties, and shielding properties and have been used in many applications, but there are problems such as low strength and poor shape stability. For improvement, it has been used by laminating with another non-woven fabric. At this time, as a method for laminating and integrating the nonwoven fabrics, a resin or a heat-sealing fiber that becomes a binder by spraying or transfer has been used. However, these methods require heat treatment for the purpose of drying or melting and bonding the resin, and are not very preferable from the viewpoint of environmental pollution caused by exhaust gas and energy saving. In addition, there is a problem that the binder resin forms a film at the interface between the nonwoven fabrics, resulting in a decrease in sound absorption.
[0003]
On the other hand, the method of laminating and integrating ultrafine fiber nonwoven fabric and long fiber nonwoven fabric is known as S / M / S, which is known as S / M / S. How to do is known. However, these nonwoven fabrics have a problem in that they lack volume and have a hard texture, which limits their applications.
Non-woven fabrics, called coforms, in which short fibers of about 20 to 30 microns are blown into the melt-blown nonwoven fabric are combined and commercialized. However, the problem is that the form stability and moldability are poor.
Sound absorbing materials incorporated into automobile interior materials and electrical products are often three-dimensionally molded, but conventional sound absorbing materials can follow the deformation when the diaphragm is deep when molded and the deformation at the throttle is large. There is a problem that it doesn't break.
In addition, when ultrafine fibers are used to improve the sound absorption performance, there is a problem that the specific surface area is increased and the combustion becomes easy. In particular, when the ultrafine fibers are made by the melt blow method, polypropylene is generally used, and it is easy to burn from the viewpoint of the material, and there is a safety problem in applications where it contacts a heating element such as a motor. It is done.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a low-cost sound-absorbing material that has high sound-absorbing performance, is thin, lightweight, and has good shape stability. In particular, in automobiles, lightweight and excellent sound absorbing materials are required for improving fuel efficiency and comfort, and the purpose is to meet the demand. The present invention relates to a sound-absorbing material having good formability that does not break even if the deformation at the throttle portion during molding is large. It is another object of the present invention to provide a sound absorbing material with high flame retardancy.
[0005]
[Means for Solving the Problems]
The present invention takes the following means in order to solve this problem. In the first invention, a non-woven fabric (A) having a basis weight of 20 to 200 g / m 2 and a non-woven fabric (B) having a basis weight of 50 to 2000 g / m 2 including a very fine elastomer fiber having a fiber diameter of 6 microns or less is laminated and integrated. The sound-absorbing material is characterized by having a short fiber loop outside the nonwoven fabric (A) and having a breaking elongation at 25 ° C. of 25% or more.
[0006]
2nd invention consists of a short fiber whose fiber length of the fiber which comprises the said nonwoven fabric (B) is 50-150 mm, and this nonwoven fabric (B) and said nonwoven fabric (A) are laminated and integrated by the needle punch method. The sound-absorbing material according to the first aspect of the present invention.
[0007]
The third invention is the sound absorbing material according to claim 1 or 2, wherein the nonwoven fabric ( B ) is made of polyester .
[0008]
According to a fourth aspect of the invention, there is provided a long fiber nonwoven fabric having an elongation at 25 ° C of 25% or more on one side of the sound absorbing material according to any one of the first aspect to the third aspect of the nonwoven fabric (A). It is a sound-absorbing material characterized by being laminated.
[0009]
A fifth invention is the sound-absorbing material according to the fourth invention, wherein the long-fiber nonwoven fabric is made of a flame-retardant polyester.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The nonwoven fabric used in the present invention requires that at least two kinds of nonwoven fabrics are joined and integrated. In order to control air permeability and the like, it is also a desirable form to laminate a film or the like on a nonwoven fabric layer containing ultrafine fibers. Further, it is preferable to make a composite with a woven fabric or a woven fabric depending on the usage form. Furthermore, a surface layer nonwoven fabric having a design or color with a color or pattern may be attached to the outside of the composite nonwoven fabric, and can be suitably used as a soundproofing material for vehicle interior materials or building materials.
[0011]
The nonwoven fabric (A) containing ultrafine fibers having a fiber diameter of 6 microns or less in the present invention preferably contains 10% or more of ultrafine fibers by weight. Although the whole nonwoven fabric may be comprised only with the ultrafine fiber, when the content rate is too small, it is difficult to obtain the effect due to the ultrafine fiber characteristics. The fiber diameter of the ultrafine fiber is preferably 5 microns or less, particularly preferably 0.5 to 4 microns or less, and most preferably about 1.5 to 3 microns.
[0012]
The method for producing ultrafine fibers is not particularly limited, but non-woven fabrics obtained by a melt blow method capable of random arrangement of fibers and low production costs are particularly preferred. Since the melt-blown nonwoven fabric has low strength, it is also preferable to use a nonwoven fabric joined to a reinforcing nonwoven fabric such as a spunbond nonwoven fabric, or to laminate three or more nonwoven fabrics simultaneously in the lamination step. At this time, it is preferable to install the spunbonded nonwoven fabric having excellent wear resistance so that it is on the surface layer side during use. Embossed laminated nonwoven fabrics of melt blown nonwoven fabric and spunbond nonwoven fabric are called and commercially available under names such as S / M / S and S / M (S is a spunbond nonwoven fabric and M is a meltblown nonwoven fabric). Represent).
[0013]
In addition, it is one of preferable modes to use ultrafine fibers obtained by using split fibers or sea-island type fibers. The split fibers may be those that have been split in advance, or may be split simultaneously during the lamination process.
[0014]
Nonwoven fabric comprising a microfine fiber (A) is a basis weight of 20 to 200 g / m Ru 2 der. When the basis weight is smaller than 20 g / m 2, the sound absorption effect of the ultrafine fiber cannot be expected so much, which is not preferable. On the other hand, if the basis weight exceeds 200 g / m 2 , there may be a problem that wrinkles may occur when the composite with the short fiber nonwoven fabric is formed or the bonding force is weak. Further, even if the basis weight is too large, the intended improvement effect such as sound absorption is not changed so much, which is not preferable from the viewpoint of cost reduction and weight reduction.
[0015]
The material constituting the nonwoven fabric (A) containing ultrafine fibers, preferably from the viewpoint of deformation following ability at the time of stretch recovery highly elastomeric fibers deep drawing, similar to the short fiber nonwoven fabric laminated on the ultrafine fiber material It is easy to recycle and is more preferable. On the other hand, there is no problem even if fibers made of a plurality of materials are mixed.
[0016]
When using the ultrafine fibers made by melt-blown method, it is preferred that the fibers are long fibers cut surface using a little house elastomer. When laminating an ultra-fine fiber nonwoven fabric with another nonwoven fabric by the needle punch method, there is a mark on the hole by the needle, and air leaks through the hole, causing a problem that the sound absorption rate decreases. However, if it is an elastomer, it is deformed and returns to its original shape, so the size of the hole is small and the sound absorption rate hardly decreases. Within the scope of the study by the inventors, when the piercing density is 100 locations / cm 2 or more, the sound absorption performance is remarkably lowered when using ultrafine fibers made of non-elastomer, whereas the performance is almost lowered in the case of elastomer. However, by increasing the piercing density, it was possible to increase the peel strength of the laminate and to increase the form stability.
[0017]
Next, the nonwoven fabric (B) laminated on the nonwoven fabric containing ultrafine fibers preferably has a fiber diameter of 7 to 40 microns, more preferably 7 to 20 microns. A fiber diameter smaller than 7 microns does not cause a major problem directly, but is not preferable in terms of productivity such as spinning performance from a card machine. Further, if the fiber diameter is significantly smaller than 7 microns, the lamination effect according to the present invention is reduced, so that it is preferably thicker than the ultrafine fiber. In addition, other problems may occur, such as the non-woven fabric being easily fluffed. On the other hand, if the fiber diameter is larger than 40 microns, the contribution to the sound absorption performance is reduced, which is not preferable.
[0018]
In the present invention, the short-fiber nonwoven fabric (B) is laminated with the nonwoven fabric containing the ultrafine fibers because the nonwoven fabric containing the ultrafine fibers tends to sag easily, has low form stability, tends to fluff, and tends to cause problems in maintaining bulkiness. It is carried out for the purpose of improving problems such as, and obtaining high cushioning properties and vibration damping properties. In addition, it is generally considered that the sound absorbing material can obtain higher performance as the thickness is larger, and is laminated for the purpose of controlling the thickness. It is possible to design a sound-absorbing material with high sound-absorbing performance and good shape stability by mixing thin fibers that contribute to improving sound-absorbing performance and thick fibers that contribute to improving shape stability at an appropriate ratio. .
[0019]
The nonwoven fabric (B) in the present invention is a short fiber nonwoven fabric having a basis weight of 50 to 2000 g / m 2 . When the basis weight is less than 50 g / m 2 , the lamination effect is small, which is not preferable in terms of bulkiness and soft texture of the nonwoven fabric. On the other hand, if the basis weight is larger than 2000 g / m 2 , the thickness becomes too large to take up space and the weight becomes unfavorable.
[0020]
When the nonwoven fabric (B) in the present invention is a short fiber, the fiber length is preferably 38 to 150 mm, particularly preferably 50 to 150 mm. Within the scope of the study by the present inventors, the longer the fiber length, the better the sound absorption coefficient. However, if the fiber length is too long, the spinning property from the card deteriorates, which is not preferable. The short fiber may be a single component, but may be a mixture of two or more types or a multicomponent composite fiber. If the weight fraction is about 30% or less in order to adjust the stiffness of the nonwoven fabric, the characteristics do not change much even if thicker fibers are mixed. If there are too many thick fibers, problems such as the feeling of the nonwoven fabric becoming too hard are likely to occur, which is not preferable. It is also preferable to use heat-fusible fibers having different melting points from the viewpoint of improving dimensional stability. The weight-based packing density of the short fiber nonwoven fabric is preferably 0.005 to 0.3 g / cm 3 from the viewpoint of bulkiness. When the packing density is too small, the form stability is deteriorated, which is not preferable. When the packing density is higher than 0.3 g / cm 3 , the sound absorption tends to be deteriorated, and it becomes difficult to satisfy the object of the present invention.
[0021]
It is preferable to integrate the nonwoven fabric by a needle punch method. The needle punch method is generally implemented as a nonwoven fabric processing method, and details are described in detail in “Basics and Applications of Nonwoven Fabrics” edited by the Nonwoven Fabric Research Society of the Japan Textile Machinery Society. It is well known that composites of nonwoven fabrics are made using this needle punching method, but ultrafine fiber nonwoven fabrics are made by combining ultrathin nonwoven fabrics with uniform eyes and bulky short fiber nonwoven fabrics with relatively thick fibers using a needle punch machine. As far as the inventor knows, the product cannot be found in the market because it is thought that the fine-fiber characteristics are difficult to obtain due to the perforation of the holes and the sound absorption performance and filter performance are lowered.
[0022]
When performing needle punching, it is preferable to use a needle (needle) thinner than 38th, particularly preferably 40-42. The needle enters the short fiber nonwoven fabric side, to the outside of the nonwoven fabric comprising ultrafine fibers Ru cause of short fibers loop.
[0023]
A nonwoven fabric containing ultrafine fibers alone is prone to fluff because the fibers get caught or cut by other objects, but in the laminated nonwoven fabric of the present invention, short fiber loops prevent surface fluffing of the nonwoven fabric containing ultrafine fibers. In other words, it has been found that it becomes a cushion layer and helps to prevent breakage by relaxing the external force applied to the ultrafine fiber nonwoven fabric layer. Also, when laminating with another non-woven fabric or film having a degree of elongation higher than 25%, by bonding the loop and the third material to be laminated, an extra fine fiber is applied when an external force such as bending or pulling is applied. It has also been found that it is possible to prevent the non-woven fabric containing the material from being destroyed.
[0024]
In order to form an appropriate loop size, the needle depth of the needle punch is preferably 15 mm or less. Above that, the nonwoven fabric is often torn by impact when the needle and the short fiber penetrate through the ultrafine fiber nonwoven fabric, and the needle hole after penetrating becomes too large, which is not preferable. The needle depth is preferably 5 mm or more, although it depends on the position of the needle barb, in order to prevent the peeling by increasing the entanglement of the nonwoven fabric. The puncture density is preferably 30 to 200 / cm 2 . If the puncture density is less than 30 / cm 2, the problem of peeling of the nonwoven fabric is likely to occur. If the puncture density is greater than 250 / cm 2, the total area of the openings due to the puncture is too large, or the nonwoven fabric containing ultrafine fibers is torn or broken. It is easy to occur and is not so preferable.
[0025]
The breaking elongation of the laminated sound absorbing material needs to be 25% or more, preferably 50% or more, and particularly preferably 100% or more. A non-woven fabric having a breaking elongation of less than 25% is not preferable because it cannot follow the deformation at the time of molding and the sound absorption coefficient is remarkably lowered due to breakage in the ultrafine fiber layer or the like. Further, since there is deformability even in the processing step, it becomes easy to avoid problems such as cutting due to poor control of stress. Processing at a molding temperature from room temperature to around 200 ° C. can be considered, but there is almost no problem as long as the requirements of the present invention are satisfied.
[0026]
For the purpose of preventing fluff of the sound-absorbing material and improving the form stability, it is particularly suitable as a counterpart to be laminated on the sound-absorbing material described in the first to third aspects, with a fiber diameter of 5 to 20 microns and a basis weight of 20 to 250 g. / M 2 long fiber nonwoven fabric. If the fiber diameter of the long-fiber nonwoven fabric is less than 5 microns, it is not preferable because the effect of improving the shape stability is small. If the fiber diameter exceeds 20 microns, the unevenness of the nonwoven fabric is noticeable and not so preferable. With regard to the basis weight, if it is less than 20 g / m 2 , the unevenness of the formation is noticeably unfavorable. On the other hand, if the basis weight exceeds 250 g / m 2 , it is not preferable because it does not conform to the gist of the present invention for weight reduction.
[0027]
It is preferable that the surface of the laminated nonwoven fabric is colored or printed with a pattern to have a design. Thereby, it becomes possible to harmonize visually and the surroundings visually as a sound absorbing material used for a sound absorbing material of a building structure or an automobile interior material. The fiber material is not particularly limited as long as the elongation is 25% or more, but a thermoplastic elastomer or a polyester fiber having a birefringence of less than 0.08 is particularly preferable.
[0028]
The long fiber nonwoven fabric to be bonded is preferably a flame retardant type. In order to make it flame-retardant, it is preferable to use a material that does not contain a halogen and is coated with a phosphorus-based flame retardant or copolymerized with a flame-retardant component. Even if other components are flammable, it is relatively easy to achieve normal flame retardant standards by providing a flame retardant layer on the surface layer.
[0029]
【Example】
The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation methods in the examples were as follows.
[0030]
(Average fiber diameter): In a scanning electron micrograph, 20 or more fiber side surfaces were measured and measured from the average value. When the ultrafine fiber nonwoven fabric was melt blown, the fiber diameter variation was large, so 100 or more were measured and the average value was adopted.
[0031]
(Weight and packing density): A value obtained by cutting a nonwoven fabric into 20 cm square and measuring its weight was converted to 1 m 2 to obtain a basis weight. The packing density was obtained by calculating the unit of g / cm 3 by obtaining a value obtained by dividing the basis weight of the nonwoven fabric by the thickness under a load of 20 g / cm 2 .
[0032]
(Peeling resistance): The operation of bending the composite nonwoven fabric by 90 degrees by hand was repeated 20 times, and whether or not peeling occurred was visually evaluated.
[0033]
(Breaking elongation): The nonwoven fabric was cut into a rectangle having a length of 20 cm and a width of 5 cm. The% elongation at break was determined when the low-speed elongation tensile measurement was performed at a room temperature of 25 ° C. with a test length of 10 cm and a crosshead of 10 cm / min.
[0034]
(Sound Absorption Rate): The normal incidence method sound absorption rate% was determined according to JIS A-1405. The average value of 1000 Hz and 2000 Hz was used as a representative value.
[0035]
[Example 1]
A short fiber with an average fiber diameter of 14 microns, a fiber length of 51 mm, and a crimped number of 12 per inch on a polyester elastomer (Perprene P type manufactured by Toyobo Co., Ltd.) with an average fiber diameter of 3 microns and a basis weight of 100 g / m 2 A needle punch non-woven fabric made of polyethylene terephthalate having a basis weight of 250 g / m 2 and a packing density of 0.06 g / cm 3 is layered, and needle punch lamination is performed using a 40th needle with a puncture density of 50 / cm 2 and a needle depth of 10 mm. Processing was carried out. Even when the sound absorbing material was bent about 20 times, no problem of peeling occurred, and the sound absorption rate was as high as 72%, which was good. Since the breaking elongation of the nonwoven fabric was as high as 180%, it could be molded without any problems even when the maximum drawing depth was about 50% at 100 ° C.
[0036]
[Example 2]
In Example 1, a flame-retardant polyester spunbonded nonwoven fabric (Heim) manufactured by Toyobo Co., Ltd. having an average fiber diameter of 14 microns and a basis weight of 20 g / m 2 was laminated together on the melt blown nonwoven fabric layer side during the needle punching method. Even if the produced nonwoven fabric was bent about 20 times, the problem of peeling did not occur, and the sound absorption rate was as high as 70%, which was good. Even when the surface was rubbed with a finger, it was not fuzzy at all and was excellent in form stability. The breaking elongation of the nonwoven fabric was 27%. Although molding at 100 ° C. was possible, the molding temperature was increased to 150 ° C. in order to improve the appearance of the drawn portion. Even when the maximum molding drawing depth was about 50%, molding was possible without any problem.
[0037]
[Comparative Example 1]
The average fiber diameter of 3 microns, except polypropylene meltblown nonwoven having a basis weight of 15 g / m 2 was prepared the laminated nonwoven fabric under the same conditions as in Example 1. The sound absorption coefficient was measured and found to be as good as 65%. The breaking elongation of the nonwoven fabric was 15%, and when molding was performed at 100 ° C. and the maximum drawing depth was about 50%, the melt blown nonwoven fabric was broken near the needle hole, which was a problem. When the temperature was raised to 150 ° C., the melt-blown non-woven fabric was formed into a film at the forming deep drawing portion, and the thickness became too thin, which was a problem in appearance.
[0038]
[Comparative Example 2]
Using short woven fiber of polyethylene terephthalate with an average fiber diameter of 14 microns, fiber length of 51 mm, and a short fiber nonwoven fabric of 12 pieces / inch of crimps and a basis weight of 500 g / m 2 , both from the front and the back using a 40th needle Needle punching was performed at a puncture density of 30 / cm 2 and a needle depth of 10 mm to obtain a nonwoven fabric with a packing density of 0.05 g / cm 3 . Although the nonwoven fabric had a higher basis weight than that of Example 1, the sound absorption coefficient was measured to be 21%, which was a problem.
[0039]
【The invention's effect】
The sound-absorbing material of the present invention is a sound-absorbing material that has high sound-absorbing performance, is thin and lightweight, has good shape stability, and exhibits good moldability. In particular, it can be used as a lightweight and excellent sound-absorbing material in order to improve fuel efficiency and comfort in automobile applications. In addition, it can be suitably used as a sound absorbing material in a wide range of other industrial applications.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000359693A JP3705420B2 (en) | 2000-11-27 | 2000-11-27 | Sound absorbing material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000359693A JP3705420B2 (en) | 2000-11-27 | 2000-11-27 | Sound absorbing material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002161465A JP2002161465A (en) | 2002-06-04 |
| JP3705420B2 true JP3705420B2 (en) | 2005-10-12 |
Family
ID=18831424
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000359693A Expired - Fee Related JP3705420B2 (en) | 2000-11-27 | 2000-11-27 | Sound absorbing material |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3968648B2 (en) * | 2002-06-18 | 2007-08-29 | 東洋紡績株式会社 | Sound absorbing material |
| JP4171441B2 (en) * | 2003-10-02 | 2008-10-22 | 丸五ゴム工業株式会社 | Waterproof cover and manufacturing method thereof |
| JP5624870B2 (en) * | 2010-12-17 | 2014-11-12 | 株式会社ブリヂストン | Foam molded body and method for producing foam molded body |
| WO2014030730A1 (en) * | 2012-08-23 | 2014-02-27 | 三井化学株式会社 | Melt-blown nonwoven fabric and use thereof |
| JP6507681B2 (en) | 2015-01-30 | 2019-05-08 | 株式会社オートネットワーク技術研究所 | Sound absorbing material and wire harness with sound absorbing material |
| CN106150637B (en) * | 2016-08-31 | 2018-12-28 | 芜湖恒耀汽车零部件有限公司 | The processing molding method of silencing cotton coating in automobile exhaust pipe muffler |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5936757A (en) * | 1982-08-19 | 1984-02-29 | 株式会社クラレ | Laminate nonwoven fabric and production thereof |
| CA2024369C (en) * | 1989-09-29 | 2001-02-27 | Bernard Cohen | Increased pile density composite elastic material |
| JP3516372B2 (en) * | 1996-08-05 | 2004-04-05 | 旭コルク工業株式会社 | Felt sound absorbing material |
| JP3632876B2 (en) * | 1997-01-27 | 2005-03-23 | 日産自動車株式会社 | Sound insulation structure |
| JP3415400B2 (en) * | 1997-08-18 | 2003-06-09 | ユニチカ株式会社 | Sound absorbing material |
| JP2000008260A (en) * | 1998-06-16 | 2000-01-11 | Asahi Chem Ind Co Ltd | Sound-absorbing material |
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| JP2002161465A (en) | 2002-06-04 |
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