JP3632876B2 - Sound insulation structure - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、高性能の自動車用遮音構造体に係り、更に詳しくは、高い吸音性能と遮音性能を両立させた自動車用遮音構造体に関するもので、自動車用吸遮音材、フロアーインシュレーター及びダッシュパネルに取り付けられる自動車用ダッシュインシュレーター等の自動車用内装吸遮音材として好適に用いられる。
【０００２】
【従来の技術】
近年、自動車用内装材、特にフロアインシュレーターやダッシュインシュレーターには良好な遮音性能と吸音性能が要求されており、従来、かかる自動車用遮音構造体としては、フェルトやウレタンフォームが使用されることが多かった。しかしながら、フェルトは、賦形性が悪いことに起因してパネルとの密着性が悪くなるので、一般的に吸遮音性能が劣る。また、フロアーインシュレーター等に使用されると、敷設されているワイヤーハーネス等による凹凸を吸収できないことがあり、カーペット表皮に凹凸が発生し、見栄えが悪くなることがある。更に、解繊した繊維には天然繊維が含まれているため、品質上の安定性に欠ける。加えて繊維間の結合が弱いために、経時的なへたりを生じるという欠点があった。
【０００３】
一方、ウレタンフォームを遮音構造体として用いる場合には、カーペット表皮とウレタンフォームとの接着工程が必要となり、高コストとなる。発泡成形型中にカーペット表皮とウレタン発泡原料を投入して一体成形する方法も開発されているが、樹脂注入、発泡固着工程が必要となるため生産性が劣るほか、設備も大規模になり、また、ウレタン発泡材の原料を用いるため作業環境が悪く、排気設備も必要となる。更に、ウレタンフォームはリサイクルが困難であり、環境上問題となるため好ましくなく、フェルトに比べて硬いため遮音性能も劣っている。
【０００４】
かかる欠点を改善するために、特開昭６２−２２３３５７号公報、特開平４−２７２２６３号公報及び特開平４−１８５７５４号公報には、ポリエステル等の合成繊維不織布を用いた遮音構造体が開示されている。
ところで、熱融着繊維（バインダー繊維）を用いるサーマルボンドタイプの合成繊維製不織布は、バインダー繊維の配合量、繊維径、見かけ密度を変えることで、ばね定数や吸音性能をコントロールすることが可能である。即ち、共振点のチューニングが可能であり、ノイズ入力の大きな周波数と遮音構造体の共振点をずらすことで良好な遮音性能が得られる。
【０００５】
しかしながら、ノイズ入力の大きな周波数が広い領域に亘る場合、共振点のチューニングのみでは遮音が不十分であり、遮音構造体の高ダンピング化が必要となる。ところが、従来のフェルトやウレタンフォームや合成繊維不織布を用いた遮音構造体で高ダンピングを実現するのは難しく、そのコントロールも困難なのが現状である。このため、遮音構造体を多層構造とし、構造体の一層をメルトブロー製法により得られる超極細繊維不織布から成る遮音構造体が考案されている（特願平７−１５１５４９号）。
【０００６】
【発明が解決しようとする課題】
上記多層型遮音構造体を用いることにより、ダンピング性能に優れ、且つ、ダンピング特性のコントロールが可能である。しかしながら、この多層型遮音構造体では超極細繊維層が主たる音の入射面に対して反対側又は中間に位置するため、超極細繊維不織布のもつ大きな特徴である高吸音性が発揮できていない。また、超極細繊維不織布はもともと動ばね定数が非常に大きく、超極細繊維層に対して他の層の厚さが十分確保されていない場合、ばね定数が増加し遮音性能が低下する等の課題があった。更に、吸遮音構造体の性能は主に吸音性能とばね特性で決まるが、この２つの性能は二律背反的な側面を持ち、高吸音性と低ばね化は両立が難しかった。
【０００７】
本発明は、このような従来技術の有する課題に鑑みてなされたものであり、その目的とするところは、超極細繊維不織布の持つ大きな特長である高吸音性を維持しつつ、ばね定数を低く抑えることで、高吸音性と高遮音性（低ばね化）とを兼備した自動車用遮音構造体を提供することにある。
【０００８】
【課題を解決するための手段】
本発明者らは、上記課題を解決すべく鋭意研究した結果、上述の如き超極細繊維不織布の高い吸音性能は膜共振吸音形態と多孔質構造吸音形態の二種類の吸音形態の混和に起因していることと、超極細繊維不織布の動ばね定数はそのほとんどを空気ばねが占めていることとを知見した。そこで、遮音構造体を多層化して超極細繊維不織布を主たる音の入射面となる表面層に配し、表面層の厚さや密度及び反対側に位置する内面層の厚さや密度等を特定したところ、上記課題が解決されることを見出し、本発明を完成するに至った。
【０００９】
即ち、本発明の自動車用遮音構造体は、主たる音の入射方向から順に表面層、内面層及び背面層から成る三層構造を成し、この表面層又は背面層と内面層とは繊維配合の異なる繊維集合体から成り、この表面層と背面層とがメルトブロー製法により得られる繊維径０．１〜１０μｍの繊維から成る平均見かけ密度０．０３〜０．０６ｇ／ｃｍ３、厚さ５〜１５ｍｍのポリプロピレン製不織布で構成され、上記内面層の厚さが上記表面層及び背面層のうちの厚さの厚い層に対して２〜５倍であることを特徴とする。
【００１０】
【作用】
上述の如く、本発明者らは、ポリプロピレン製超極細繊維不織布の高い吸音性能は膜共振吸音形態と多孔質構造吸音形態の二種類の吸音形態の混和に起因していることと、ポリプロピレン製超極細繊維不織布の動ばね定数はそのほとんどを空気ばねが占めていることを解明した。
【００１１】
即ち、ポリプロピレン製超極細繊維不織布は従来の合成繊維不織布に比べて繊維径が細いため繊維表面積が非常に大きく流動空気との摩擦が大きい。このためポリプロピレン製超極細繊維不織布は通気抵抗が極めて大きく、不織布の表層の一部が膜として作用し膜共振による吸音を起こしている。従来の合成繊維不織布にはみられない５００Ｈｚ付近の高い吸音性能は主にこのことに起因している。
【００１２】
本発明では、ポリプロピレン製超極細繊維不織布を多層化した遮音構造体の主たる音の入射面となる表面層に配設することで膜共振により吸音を起こさせ、ポリプロピレン製超極細繊維不織布単独とほぼ同等の高い吸音性能を得ることができる。
また、遮音構造体を主たる音の入射方向から順に表面層、内面層、背面層から成る三層構造体とし、表面層と背面層とをポリプロピレン製超極細繊維不織布とすれば、主たる音源のみならず反射音等に対しても高い吸音性能を持たせることができる。
【００１３】
ところで、動ばね定数は繊維ばねと空気ばねで構成されているが、その高い通気抵抗性が災いしてポリプロピレン製超極細繊維不織布の空気ばねは繊維ばねに対して数倍から十数倍に達しており、ポリプロピレン製超極細繊維不織布単独では動ばね定数が非常に大きく遮音性能は低くなる。そこで、本発明では、ポリプロピレン製超極細繊維不織布の厚さに対して２〜５倍の厚さを有する通気抵抗の小さいポリエステル繊維製不織布と積層し、遮音構造体全体の空気ばねを低下させることで動ばね定数を大幅に小さくしている。
【００１４】
以上の知見より、本発明においては、遮音構造体を多層化し、主たる音の入射面となる表面層にポリプロピレン製超極細繊維不織布を配し、音の入射面に対して反対側に位置する内面層に、表面層に対して２〜５倍の厚さを持たせることにより、優れた吸音性能と遮音性能を両立させることができる。
【００１５】
【発明の実施の形態】
以下、本発明の自動車用遮音構造体について詳細に説明する。
本発明の多層型遮音構造体は、上述のごとく、表面層と内面層とを備えるが、主たる音の入射面を表面層、音の入射面に対して反対側に位置する面を内面層と称する。また、三層構造をなす場合には、主たる音の入射方面から順に表面層、内面層及び背面層と称する。
本発明の遮音構造体の構成の概略を図１及び２に示す。
【００１６】
本発明の遮音構造体において、表面層及び背面層を構成する不織布はメルトブロー製法により得られる超極細繊維から成る。繊維の材質としては、コスト、製造の容易さからポリプロピレンが好ましい。また、内面層を構成する不織布は、コスト、成形性、耐久性、加工後の性能安定性等から判断してポリエステル繊維製であることが好ましい。
【００１７】
また、上記表面層及び背面層はメルトブロー製法により得られる繊維径０．１〜１０μｍの超極細繊維から成る不織布で構成することが必要である。これは、繊維径が０．１μｍ未満の繊維の入手が困難であり、また緩衝材としての剛性を得難く、他方、繊維径が１０μｍを超えると膜吸音を起こすほどの通気抵抗が得られず、吸音性能が悪化することがあるためである。
【００１８】
表面層及び背面層の平均見かけ密度は，０．０３〜０．０６ｇ／ｃｍ３の範囲とすることを要す。平均見かけ密度が０．０３ｇ／ｃｍ３未満では、フロアーインシュレーターとして用いられた場合、クッション性が極端に低下し、内面層を硬くしても荷重時の沈み込みが生じることがある。また、０．０６ｇ／ｃｍ３を超えると遮音性能、乗り心地等の低下が生じ、成形時の追従性も悪化することがあるためである。
【００１９】
更に、表面層及び背面層の厚さは、５〜１５ｍｍの範囲とすることを要す。この厚さが５ｍｍ未満では超極細繊維性不織布の効果が小さく、高い吸音性能は得られないことがある。他方、厚さが１５ｍｍを超えると積層体全体の厚さが厚くなりすぎて設置上問題となることがある。
【００２０】
一方、内面層の厚さは、表面層の厚さの２〜５倍とすることが必要である。三層構造の場合は、内面層の厚さは、表面層、背面層のうち厚さの厚い層に対して２〜５倍とすることが好ましい。２倍未満では、超極細繊維製不織布の空気ばねを大きく低下させることができず、動ばねが大きくなり遮音性が劣ることがある。他方、５倍を超えると積層体全体の厚さが厚くなりすぎて設置上問題となることがあるためである。
【００２１】
また、内面層を構成する不織布は１〜５０デニールの範囲の繊維径を有する繊維から成ることが好ましく、また、平均見かけ密度が０．０１〜０．０７ｇ／ｃｍ３の範囲とすることが好ましい。
繊維径が１デニール未満では適度なクッション性が得難く、また耐久性も低下することがある。更に、防糸速度が大幅に低下したり、カード通過性が悪く不織布の品質が悪化するおそれがある。他方、５０デニールを超えると不織布が硬くなり過ぎ、動ばね定数が大きくなり遮音性が低下することがある。また、平均見かけ密度が０．０１ｇ／ｃｍ３未満では、クッション性、耐久性が大幅に低下し、０．０７ｇ／ｃｍ３を超えると内面層の空気ばねが大きくなり超極細繊維製不織布の空気ばねを低下させることができず、遮音性が劣るほか、軽量化の要求にも反することになる。
【００２２】
また、本発明においては、内面層を構成する不織布を少なくとも２種類のポリエステル繊維から構成し、６０〜９５重量％の繊維１をポリエチレンテレフタレート繊維とし、５〜４０重量％の繊維２を、鞘部の融点が繊維１のそれより１００℃以上低い共重合ポリエステルである芯鞘構造を有するポリエステル繊維とすることが好ましい。
ここで、繊維１をポリエチレンテレフタレート繊維とするのは、バインダー繊維との融点の差を確保し、選択できるバインダー繊維の融点幅を広くするためである。
【００２３】
また、繊維２はバインダー繊維として機能する。繊維２の鞘部の融点を繊維１より１００℃以上低くするのは、融点の差が１００℃未満であると表面層及び背面層を構成しているポリプロピレン性の超極細繊維の融点と重なってしまうため、成形時の温度条件が厳しくなるためである。場合によっては、超極細繊維が溶融し所期の性能が得られない可能性もある。融点差は大きすぎても問題になることはないので特に限定されるものではないが、１５０℃以上では繊維２の融点が下がりすぎて取扱が困難となる。また、繊維２の芯部の材質も特に限定されるものではないが、バインダー繊維として機能させやすくするために、ポリエチレンテレフタレートとするのが好ましい。
【００２４】
繊維１を６０〜９５重量％、繊維２を５〜４０重量％とするのは以下の理由による。即ち、繊維１が６０重量％未満、繊維２が４０重量％を超えるとバインダー繊維量が多すぎてコストの上昇やクッション性の悪化を招くことがある。また、繊維１が９５重量％を超え、繊維２が５重量％未満であると、バインダー繊維量が少なすぎて成形性や耐久性が低下することがある。
【００２５】
また、積層構造体全体の厚さは、良好な吸音、遮音性能を保ち、且つ設置上問題とならないように２０〜５０ｍｍ程度とすることが好ましい。
また、本発明の遮音構造体は、自動車等のダッシュインシュレーターやフロアーインシュレーターとして好適に用いることができる。
【００２６】
【実施例】
以下、本発明を実施例、参考例、比較例及び従来例により更に詳細に説明するが、本発明はこれら実施例に限定されるものではない。
（参考例１）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００２７】
（参考例２）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合２デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００２８】
（参考例３）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合２デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０６ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００２９】
（参考例４）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合１３デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ３０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００３０】
（参考例５）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合２デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２５ｍｍ、平均見かけ密度０．０６ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００３１】
（参考例６）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合６デニール×５１ｍｍのポリエステル繊維：９０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：１０％で厚さ２０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００３２】
（実施例１）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層及び背面層に、繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００３３】
（実施例２）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層及び背面層に、繊維配合２デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００３４】
（実施例３）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ１０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合２デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０６ｇ／ｃｍ３のポリエステル製不織布を内面層に、メルトブロー製法により得られる平均繊維径３μｍ、厚さ６ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を背面層に用い、積層して自動車用遮音構造体を作成した。
【００３５】
（実施例４）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合１３デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ３０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を内面層に、メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を背面層に用い、積層して自動車用遮音構造体を作成した。
【００３６】
（従来例１）
３０ｍｍのクリアランスを有する注入発泡型内にポリオールとしてプロピレンオキサイド１，２，６−ヘキサントリオール：１００部、水：２部、界面活性剤：１部、カーボンブラック：０．５部から成るＡ液とトリレンジイソシアナート：１００部、シリコンオイル：０．５部から成るＢ液をポリオールに対してイソシアナート１．２５倍当量を低圧注入して発泡させ、厚さ３０ｍｍ、平均見かけ密度０．０６ｇ／ｃｍ３のウレタンフォームを得て自動車用遮音構造体とした。
【００３７】
（従来例２）
豊和繊維工業製、厚さ３０ｍｍ、平均見かけ密度０．０６ｇ／ｃｍ３のフェルト（商品名フェルトップ）を用い、自動車用遮音構造体とした。
【００３８】
（従来例３）
繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ３０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を用い、自動車用遮音構造体とした。
【００３９】
（従来例４）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ３０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を用い、自動車用遮音構造体とした。
【００４０】
（比較例１）
繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ２０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を表面層に、メルトブロー製法により得られる平均繊維径３μｍ、厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００４１】
（比較例２）
繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ１０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を表面層に、メルトブロー製法により得られる平均繊維径３μｍ、厚さ２０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００４２】
（比較例３）
メルトブロー製法により得られる平均繊維径３μｍ、厚さ２ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を表面層に、繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ３０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００４３】
（比較例４）
繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ１０ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を表面層及び背面層に、メルトブロー製法により得られる平均繊維径３μｍ、厚さ１０ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００４４】
（比較例５）
繊維配合６デニール×５１ｍｍのポリエステル繊維：８０％、２デニール×５１ｍｍの芯鞘タイプのバインダー繊維（鞘部融点１１０℃）：２０％で厚さ８ｍｍ、平均見かけ密度０．０５ｇ／ｃｍ３のポリエステル製不織布を表面層及び背面層に、メルトブロー製法により得られる平均繊維径３μｍ、厚さ３０ｍｍ、平均見かけ密度０．０４ｇ／ｃｍ３のポリプロピレン製超極細繊維不織布を内面層に用い、積層して自動車用遮音構造体を作成した。
【００４５】
（性能評価）
上記実施例１〜４、参考例１〜６、従来例１〜３及び比較例１〜５において得られた自動車用遮音構造体について１００〜１６００Ｈｚの垂直入射吸音率を測定した。また、振動伝達率測定法を用いて共振周波数よりばね定数を求めた。振動伝達率測定法では大気中の測定から全体ばね定数が、真空中の測定から繊維ばね定数がそれぞれ求められ、その差が空気ばね定数となる。
表１に各実施例、従来例及び比較例の物性データ、吸音率測定結果（５００Ｈｚ、１０００Ｈｚ）、及び各ばね定数測定結果を示す。
【００４６】
【表１】
表１より、実施例で作成された各種自動車用遮音構造体は、従来例に比べ、高い吸音率を維持しつつ、ばね定数が低く抑えられており、高吸音性と低ばね化が両立した自動車用遮音構造体であることが確認された。
また、表１より、本発明の範囲にない比較例の自動車用遮音構造体は、高吸音性と低ばね化の両立が果たされておらず、実施例の自動車用遮音構造体に比し、性能が劣ることが確認された。
【００４８】
【発明の効果】
以上説明してきたように、本発明によれば、遮音構造体を多層化し超極細繊維不織布を主たる音の入射面となる表面層に配し、表面層の厚さや密度及び反対側に位置する内面層の厚さや密度等を特定したため、超極細繊維不織布の持つ大きな特長である高吸音性を維持しつつ、ばね定数を低く抑えることで、高吸音性と高遮音性（低ばね化）が両立した自動車用遮音構造体を提供することができる。
【図面の簡単な説明】
【図１】本発明の遮音構造体の構成例（二層）を示す概略図である。
【図２】本発明の遮音構造体の構成例（三層）を示す概略図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-performance automobile sound insulation structure, and more particularly, to a vehicle sound insulation structure that achieves both high sound absorption performance and sound insulation performance. The present invention relates to an automobile sound insulation structure, a floor insulator, and a dash panel. It is suitably used as an interior sound absorbing and insulating material for automobiles such as a dash insulator for automobiles to be attached.
[0002]
[Prior art]
In recent years, automotive interior materials, particularly floor insulators and dash insulators, have been required to have good sound insulation performance and sound absorption performance. Conventionally, felts and urethane foams are often used as such sound insulation structures for automobiles. It was. However, felts generally have poor sound absorption and insulation performance because the adhesion with the panel is deteriorated due to poor formability. In addition, when used in a floor insulator or the like, unevenness due to a laid wire harness or the like may not be absorbed, and unevenness may occur in the carpet skin, resulting in poor appearance. Furthermore, since the defibrated fibers contain natural fibers, they lack quality stability. In addition, since the bonding between the fibers is weak, there is a drawback that sag occurs over time.
[0003]
On the other hand, when urethane foam is used as the sound insulation structure, an adhesion process between the carpet skin and the urethane foam is required, resulting in high cost. A method has been developed in which the carpet skin and urethane foam raw material are introduced into the foam mold, but the process of resin injection and foam fixing is required, resulting in inferior productivity and large equipment. Moreover, since the urethane foam material is used, the working environment is poor and exhaust facilities are also required. Furthermore, urethane foam is not preferable because it is difficult to recycle and causes environmental problems, and since it is harder than felt, sound insulation performance is inferior.
[0004]
In order to remedy such drawbacks, JP-A-62-223357, JP-A-4-272263, and JP-A-4-185754 disclose a sound insulation structure using a synthetic fiber nonwoven fabric such as polyester. ing.
By the way, a thermal bond type synthetic fiber nonwoven fabric using heat-bonding fibers (binder fibers) can control the spring constant and sound absorption performance by changing the amount of binder fibers, fiber diameter, and apparent density. is there. That is, the resonance point can be tuned, and a good sound insulation performance can be obtained by shifting the frequency of the large noise input and the resonance point of the sound insulation structure.
[0005]
However, when a large frequency of noise input covers a wide region, the sound insulation is insufficient only by tuning the resonance point, and it is necessary to increase the damping of the sound insulation structure. However, it is difficult to achieve high damping with a conventional sound insulation structure using felt, urethane foam, or synthetic fiber nonwoven fabric, and it is difficult to control the damping. For this reason, a sound insulation structure has been devised which comprises a sound insulation structure having a multi-layer structure, and one layer of the structure is made of an ultra-fine fiber nonwoven fabric obtained by a melt blow manufacturing method (Japanese Patent Application No. 7-151549).
[0006]
[Problems to be solved by the invention]
By using the multilayer sound insulation structure, the damping performance is excellent and the damping characteristics can be controlled. However, in this multi-layered sound insulation structure, the superfine fiber layer is located on the opposite side or the middle of the main sound incident surface, so that the high sound absorption property that is a great feature of the superfine fiber nonwoven fabric cannot be exhibited. Also, the ultra-fine fiber nonwoven fabric has a very large dynamic spring constant, and if the thickness of the other layers is not sufficiently secured relative to the ultra-fine fiber layer, the spring constant increases and the sound insulation performance decreases. was there. Furthermore, although the performance of the sound absorbing and insulating structure is mainly determined by the sound absorbing performance and the spring characteristics, these two performances have a trade-off, and it is difficult to achieve both high sound absorption and low springs.
[0007]
The present invention has been made in view of such problems of the prior art, and its object is to reduce the spring constant while maintaining the high sound absorption, which is a major feature of the ultra-fine fiber nonwoven fabric. An object of the present invention is to provide a sound insulation structure for automobiles that has both high sound absorption and high sound insulation (lower springs).
[0008]
[Means for Solving the Problems]
As a result of diligent research to solve the above problems, the present inventors have found that the high sound absorption performance of the above-described ultrafine fiber nonwoven fabric is due to the mixing of two types of sound absorption forms, a membrane resonance sound absorption form and a porous structure sound absorption form. It was found that the air spring occupies most of the dynamic spring constant of the ultra-fine fiber nonwoven fabric. Therefore, when the sound insulation structure is multilayered and the ultra-fine fiber nonwoven fabric is arranged on the surface layer that becomes the main sound incident surface, the thickness and density of the surface layer and the thickness and density of the inner surface layer located on the opposite side are specified. The present inventors have found that the above problems can be solved and have completed the present invention.
[0009]
That is, the sound insulation structure for automobiles of the present invention has a three-layer structure composed of a surface layer, an inner surface layer, and a rear layer in order from the main sound incident direction . An average apparent density of 0.03 to 0.06 g / cm 3 and a thickness of 5 to 15 mm made of fibers having a fiber diameter of 0.1 to 10 μm, which are made of different fiber aggregates, and the surface layer and the back layer are obtained by a melt blow manufacturing method. The inner surface layer is 2 to 5 times thicker than the thicker layer of the surface layer and the back layer.
[0010]
[Action]
As described above, the present inventors have found that the high sound absorbing performance of the ultrafine fiber nonwoven fabric made of polypropylene is due to the mixing of two types of sound absorbing forms, a membrane resonance sound absorbing form and a porous structure sound absorbing form, and It has been clarified that the air spring occupies most of the dynamic spring constant of the ultra-fine fiber nonwoven fabric.
[0011]
That is, since the ultrafine fiber nonwoven fabric made of polypropylene has a smaller fiber diameter than the conventional synthetic fiber nonwoven fabric, the fiber surface area is very large and the friction with flowing air is large. For this reason, the ultrafine fiber nonwoven fabric made of polypropylene has a very high airflow resistance, and a part of the surface layer of the nonwoven fabric acts as a film to cause sound absorption due to membrane resonance. This is mainly due to the high sound absorption performance near 500 Hz, which is not seen in conventional synthetic fiber nonwoven fabrics.
[0012]
In the present invention, a polypropylene super extra fine fiber nonwoven fabric is disposed on the surface layer that is the main sound incident surface of the multilayered sound insulation structure to cause sound absorption by membrane resonance, and is almost the same as the polypropylene extra fine fiber nonwoven fabric alone. Equivalent high sound absorption performance can be obtained.
If the sound insulation structure is a three-layer structure consisting of a surface layer, an inner surface layer, and a back layer in order from the main sound incident direction, and the surface layer and the back layer are made of polypropylene microfiber nonwoven fabric, only the main sound source Therefore, it is possible to provide high sound absorption performance against reflected sound.
[0013]
By the way, the dynamic spring constant is composed of fiber springs and air springs. However, the high airflow resistance is damaged, and the air springs of polypropylene ultra-fine fiber nonwoven fabrics are several to ten times the fiber springs. In addition, the polypropylene ultra-fine fiber nonwoven fabric alone has a very large dynamic spring constant and low sound insulation performance. Therefore, in the present invention, the air spring of the entire sound insulation structure is lowered by laminating it with a polyester fiber nonwoven fabric having a thickness of 2 to 5 times the thickness of the polypropylene extra-fine fiber nonwoven fabric and having a small ventilation resistance. The dynamic spring constant is greatly reduced.
[0014]
From the above knowledge, in the present invention, the sound insulation structure is multilayered, a polypropylene ultrafine fiber nonwoven fabric is arranged on the surface layer that is the main sound incident surface, and the inner surface located on the opposite side to the sound incident surface By providing the layer with a thickness 2 to 5 times that of the surface layer, both excellent sound absorption performance and sound insulation performance can be achieved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the sound insulation structure for automobiles of the present invention will be described in detail.
As described above, the multilayer sound insulation structure of the present invention includes the surface layer and the inner surface layer. The main sound incident surface is the surface layer, and the surface located on the opposite side of the sound incident surface is the inner surface layer. Called. In the case of a three-layer structure, they are referred to as a surface layer, an inner surface layer, and a back layer in order from the main sound incident direction.
The outline of the structure of the sound insulation structure of the present invention is shown in FIGS.
[0016]
In the sound insulation structure of the present invention, the nonwoven fabric constituting the surface layer and the back layer is made of ultrafine fibers obtained by a melt blow manufacturing method. As a material of the fiber, polypropylene is preferable from the viewpoint of cost and ease of manufacture. Moreover, it is preferable that the nonwoven fabric which comprises an inner surface layer is made from a polyester fiber judging from cost, a moldability, durability, the performance stability after a process, etc.
[0017]
Further, the surface layer and the back layer need to be composed of a nonwoven fabric made of ultrafine fibers having a fiber diameter of 0.1 to 10 μm obtained by a melt blow manufacturing method. This is because it is difficult to obtain fibers having a fiber diameter of less than 0.1 μm, and it is difficult to obtain rigidity as a buffer material. On the other hand, if the fiber diameter exceeds 10 μm, a ventilation resistance sufficient to cause film sound absorption cannot be obtained. This is because the sound absorption performance may deteriorate.
[0018]
The average apparent density of the surface layer and the back layer needs to be in the range of 0.03 to 0.06 g / cm 3 . When the average apparent density is less than 0.03 g / cm 3 , when used as a floor insulator, the cushioning property is extremely lowered, and even when the inner surface layer is hardened, sinking may occur during loading. Further, if it exceeds 0.06 g / cm 3 , the sound insulation performance, the ride comfort and the like are lowered, and the followability at the time of molding may be deteriorated.
[0019]
Furthermore, the thickness of the surface layer and the back layer needs to be in the range of 5 to 15 mm. If the thickness is less than 5 mm, the effect of the ultrafine fibrous nonwoven fabric is small, and high sound absorption performance may not be obtained. On the other hand, if the thickness exceeds 15 mm, the thickness of the entire laminate becomes too thick, which may cause a problem in installation.
[0020]
On the other hand, the thickness of the inner surface layer needs to be 2 to 5 times the thickness of the surface layer. In the case of a three-layer structure, the thickness of the inner layer is preferably 2 to 5 times that of the thicker layer of the surface layer and the back layer. If it is less than 2 times, the air spring of the ultra-fine fiber nonwoven fabric cannot be greatly lowered, and the dynamic spring becomes large and the sound insulation may be inferior. On the other hand, when it exceeds 5 times, the thickness of the entire laminate is too thick, which may cause a problem in installation.
[0021]
The nonwoven fabric constituting the inner surface layer is preferably made of fibers having a fiber diameter in the range of 1 to 50 denier, and the average apparent density is preferably in the range of 0.01 to 0.07 g / cm 3. .
When the fiber diameter is less than 1 denier, it is difficult to obtain an appropriate cushioning property and the durability may be lowered. Furthermore, there is a possibility that the yarn-proofing speed is greatly reduced, the card passing property is poor and the quality of the nonwoven fabric is deteriorated. On the other hand, when it exceeds 50 deniers, the nonwoven fabric becomes too hard, the dynamic spring constant increases, and the sound insulation properties may decrease. Further, when the average apparent density is less than 0.01 g / cm 3 , the cushioning property and durability are significantly lowered. When the average apparent density is more than 0.07 g / cm 3 , the air spring of the inner surface layer becomes large, and the air of the nonwoven fabric made of super fine fibers The spring cannot be lowered, the sound insulation performance is inferior, and it also goes against the demand for weight reduction.
[0022]
Moreover, in this invention, the nonwoven fabric which comprises an inner surface layer is comprised from at least 2 types of polyester fiber, 60 to 95 weight% fiber 1 is made into a polyethylene terephthalate fiber, 5 to 40 weight% fiber 2 is made into a sheath part It is preferable to use a polyester fiber having a core-sheath structure which is a copolyester having a melting point of 100 ° C. lower than that of the fiber 1.
Here, the reason why the fiber 1 is a polyethylene terephthalate fiber is to secure a difference in melting point from the binder fiber and to widen the melting point width of the binder fiber that can be selected.
[0023]
Moreover, the fiber 2 functions as a binder fiber. The reason why the melting point of the sheath part of the fiber 2 is lower than the fiber 1 by 100 ° C. or more is that when the difference in melting point is less than 100 ° C., it overlaps with the melting point of the polypropylene ultrafine fiber constituting the surface layer and the back layer. This is because the temperature conditions during molding become severe. In some cases, the ultra-fine fibers melt and the desired performance may not be obtained. The difference in melting point is not particularly limited because it does not cause a problem even if the difference in melting point is too large, but at 150 ° C. or higher, the melting point of the fiber 2 is too low and handling becomes difficult. Moreover, although the material of the core part of the fiber 2 is not particularly limited, it is preferable to use polyethylene terephthalate in order to make it function as a binder fiber.
[0024]
The reason why the fiber 1 is 60 to 95% by weight and the fiber 2 is 5 to 40% by weight is as follows. That is, if the fiber 1 is less than 60% by weight and the fiber 2 is more than 40% by weight, the amount of the binder fiber may be too large, leading to an increase in cost and deterioration of cushioning properties. On the other hand, if the fiber 1 exceeds 95% by weight and the fiber 2 is less than 5% by weight, the amount of the binder fiber may be too small to lower the moldability and durability.
[0025]
The thickness of the entire laminated structure is preferably about 20 to 50 mm so as to maintain good sound absorption and sound insulation performance and not cause a problem in installation.
Moreover, the sound insulation structure of the present invention can be suitably used as a dash insulator or a floor insulator of an automobile or the like.
[0026]
【Example】
EXAMPLES Hereinafter, although an Example, a reference example, a comparative example, and a conventional example demonstrate this invention further in detail, this invention is not limited to these Examples.
( Reference Example 1 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and a polyester fiber having a fiber content of 6 denier × 51 mm: 80%, 2 denier X51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness, 20 mm thickness, average apparent density 0.05 g / cm 3 polyester non-woven fabric is used as an inner layer, and laminated to form a sound insulation structure for automobiles Created the body.
[0027]
( Reference Example 2 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and fiber blended 2 denier × 51 mm polyester fiber: 80%, 2 denier X51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness 20 mm, average apparent density 0.04 g / cm 3 non-woven fabric made of polyester is used as the inner layer, and laminated to make sound insulation structure for automobiles Created the body.
[0028]
( Reference Example 3 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and fiber blended 2 denier × 51 mm polyester fiber: 80%, 2 denier X51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness 20 mm, average apparent density 0.06 g / cm 3 non-woven fabric made of polyester is used for the inner surface layer, and laminated to make sound insulation structure for automobiles Created the body.
[0029]
( Reference Example 4 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and a polyester fiber having a fiber content of 13 denier × 51 mm: 80%, 2 denier X51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness 30 mm, average apparent density 0.05 g / cm 3 non-woven fabric made of polyester is used as the inner layer and laminated to form a sound insulation structure for automobiles Created the body.
[0030]
( Reference Example 5 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.04 g / cm 3 obtained by the melt blow manufacturing method is used as a surface layer, and fiber blended 2 denier × 51 mm polyester fiber: 80%, 2 denier * 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20%, 25 mm thick, average apparent density 0.06 g / cm 3 non-woven fabric made of polyester is used for the inner surface layer and laminated to form a sound insulation structure for automobiles Created the body.
[0031]
( Reference Example 6 )
Polypropylene ultrafine fiber nonwoven fabric made of polypropylene having an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method, and a fiber compounded 6 denier × 51 mm polyester fiber: 90%, 2 denier × 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 10% thickness 20 mm, average apparent density 0.05 g / cm 3 polyester non-woven fabric is used as an inner layer, and laminated to form a sound insulation structure for automobiles Created the body.
[0032]
(Example 1 )
Polypropylene ultrafine fiber nonwoven fabric having an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method, and a fiber compounded 6 denier × 51 mm polyester fiber: 80% 2 denier × 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness 20 mm, average apparent density 0.05 g / cm 3 polyester non-woven fabric used as inner layer, laminated A sound insulation structure was created.
[0033]
(Example 2 )
Polypropylene ultrafine fiber nonwoven fabric having an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer and a back layer, and a fiber compounded 2 denier × 51 mm polyester fiber: 80% 2 denier × 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness 20 mm, average apparent density 0.04 g / cm 3 polyester non-woven fabric is used as the inner layer, and laminated A sound insulation structure was created.
[0034]
(Example 3 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 10 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and fiber blended 2 denier × 51 mm polyester fiber: 80%, 2 denier × 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): average fiber diameter obtained by a melt blow process using a polyester non-woven fabric of 20% thickness 20 mm and average apparent density 0.06 g / cm 3 A polypropylene ultra-fine fiber nonwoven fabric having a thickness of 3 μm, a thickness of 6 mm, and an average apparent density of 0.04 g / cm 3 was used as a back layer, and laminated to create a sound insulation structure for automobiles.
[0035]
(Example 4 )
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and a polyester fiber having a fiber content of 13 denier × 51 mm: 80%, 2 denier × 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): average fiber diameter obtained by melt blow production method using polyester nonwoven fabric with 20% thickness 30 mm and average apparent density 0.05 g / cm 3 on the inner surface layer A polypropylene ultra-fine fiber nonwoven fabric having a thickness of 3 μm, a thickness of 8 mm, and an average apparent density of 0.04 g / cm 3 was used as a back layer, and laminated to create a sound insulation structure for automobiles.
[0036]
(Conventional example 1)
A liquid consisting of propylene oxide 1,2,6-hexanetriol: 100 parts, water: 2 parts, surfactant: 1 part, carbon black: 0.5 part as a polyol in an injection foaming mold having a clearance of 30 mm; B liquid consisting of tolylene diisocyanate: 100 parts, silicone oil: 0.5 parts was foamed by low pressure injection of 1.25 times equivalent of isocyanate to polyol, thickness 30mm, average apparent density 0.06g / A cm 3 urethane foam was obtained to provide a sound insulation structure for automobiles.
[0037]
(Conventional example 2)
A sound insulation structure for automobiles was formed using a felt (trade name Feltop) manufactured by Toyoka Textile Industry Co., Ltd., having a thickness of 30 mm and an average apparent density of 0.06 g / cm 3 .
[0038]
(Conventional example 3)
Fiber blend 6 denier x 51 mm polyester fiber: 80%, 2 denier x 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20%, thickness 30 mm, average apparent density 0.05 g / cm 3 polyester A non-woven fabric was used to make a sound insulation structure for automobiles.
[0039]
(Conventional example 4)
A polypropylene ultrafine fiber nonwoven fabric having an average fiber diameter of 3 μm, a thickness of 30 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method was used as a sound insulation structure for automobiles.
[0040]
(Comparative Example 1)
Fiber blend 6 denier x 51 mm polyester fiber: 80%, 2 denier x 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20%, thickness 20 mm, average apparent density 0.05 g / cm 3 polyester A sound insulation structure for automobiles by laminating a non-woven fabric made of polypropylene on the inner surface layer using a non-woven fabric made of polypropylene having an average fiber diameter of 3 μm, a thickness of 8 mm, and an average apparent density of 0.05 g / cm 3 obtained by a melt blow process. Created the body.
[0041]
(Comparative Example 2)
Fiber blend 6 denier x 51 mm polyester fiber: 80%, 2 denier x 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20%, thickness 10 mm, average apparent density 0.05 g / cm 3 polyester A sound insulation structure for automobiles using a non-woven fabric made of polypropylene as a surface layer and laminated with an ultra-fine fiber non-woven fabric made of polypropylene having an average fiber diameter of 3 μm, a thickness of 20 mm and an average apparent density of 0.05 g / cm 3 obtained by a melt blow manufacturing method. Created the body.
[0042]
(Comparative Example 3)
Polypropylene ultrafine fiber nonwoven fabric with an average fiber diameter of 3 μm, a thickness of 2 mm, and an average apparent density of 0.04 g / cm 3 obtained by a melt blow manufacturing method is used as a surface layer, and a polyester fiber having a fiber content of 6 denier × 51 mm: 80%, 2 denier X51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20% thickness 30 mm, average apparent density 0.05 g / cm 3 non-woven fabric made of polyester is used as the inner layer and laminated to form a sound insulation structure for automobiles Created the body.
[0043]
(Comparative Example 4)
Fiber blend 6 denier x 51 mm polyester fiber: 80%, 2 denier x 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20%, thickness 10 mm, average apparent density 0.05 g / cm 3 polyester A non-woven fabric made of polypropylene with an average fiber diameter of 3 μm, a thickness of 10 mm and an average apparent density of 0.04 g / cm 3 obtained by a melt blow process is used as an inner layer for the surface layer and the back layer, and laminated to form an automobile. A sound insulation structure was created.
[0044]
(Comparative Example 5)
Fiber blend 6 denier x 51 mm polyester fiber: 80%, 2 denier x 51 mm core-sheath type binder fiber (sheath part melting point 110 ° C.): 20%, thickness 8 mm, average apparent density 0.05 g / cm 3 polyester A non-woven fabric made of polypropylene is used as an inner layer for a surface layer and a back layer of a polypropylene ultra-thin fiber non-woven fabric having an average fiber diameter of 3 μm, a thickness of 30 mm and an average apparent density of 0.04 g / cm 3 obtained by a melt blow manufacturing method. A sound insulation structure was created.
[0045]
(Performance evaluation)
A normal incident sound absorption coefficient of 100 to 1600 Hz was measured for the sound insulation structures for automobiles obtained in Examples 1 to 4, Reference Examples 1 to 6, Conventional Examples 1 to 3, and Comparative Examples 1 to 5. In addition, the spring constant was obtained from the resonance frequency using the vibration transmissibility measurement method. In the vibration transmissibility measurement method, the overall spring constant is obtained from the measurement in the atmosphere, and the fiber spring constant is obtained from the measurement in the vacuum, and the difference is the air spring constant.
Table 1 shows physical property data, sound absorption measurement results (500 Hz, 1000 Hz), and spring constant measurement results of each example, conventional example, and comparative example.
[0046]
[Table 1]
From Table 1, the various sound insulation structures for automobiles created in the examples maintain a high sound absorption rate and have a low spring constant compared to the conventional example, and both high sound absorption and low springs are compatible. It was confirmed to be a sound insulation structure for automobiles.
Moreover, from Table 1, the sound insulation structure for automobiles of comparative examples not within the scope of the present invention does not achieve both high sound absorption and low springs, and is in comparison with the sound insulation structures for automobiles of the embodiments. The performance was confirmed to be inferior.
[0048]
【The invention's effect】
As described above, according to the present invention, the sound insulation structure is multilayered and the ultrafine fiber nonwoven fabric is arranged on the surface layer which is the main sound incident surface, and the thickness and density of the surface layer and the inner surface located on the opposite side. By specifying the layer thickness and density, etc., both high sound absorption and high sound insulation (low spring) are achieved by maintaining the high sound absorption, which is a major feature of ultra-fine fiber nonwoven fabrics, while keeping the spring constant low. An automobile sound insulation structure can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a configuration example (two layers) of a sound insulation structure according to the present invention.
FIG. 2 is a schematic view showing a configuration example (three layers) of a sound insulation structure according to the present invention.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02576897A JP3632876B2 (en) | 1997-01-27 | 1997-01-27 | Sound insulation structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02576897A JP3632876B2 (en) | 1997-01-27 | 1997-01-27 | Sound insulation structure |
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| Publication Number | Publication Date |
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| JPH10203268A JPH10203268A (en) | 1998-08-04 |
| JP3632876B2 true JP3632876B2 (en) | 2005-03-23 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP02576897A Expired - Fee Related JP3632876B2 (en) | 1997-01-27 | 1997-01-27 | Sound insulation structure |
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Families Citing this family (35)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP3361267B2 (en) * | 1998-02-24 | 2003-01-07 | 株式会社ブリヂストン | Fiber laminated molding |
| JP2000202933A (en) * | 1999-01-18 | 2000-07-25 | Nissan Motor Co Ltd | Sound insulating material |
| JP2000238157A (en) * | 1999-02-22 | 2000-09-05 | Hayashi Gijutsu Kenkyusho:Kk | Sound absorber structure |
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| JP2002087138A (en) * | 2000-09-18 | 2002-03-26 | Howa Kogyo Kk | Raising material for automobile |
| JP3705420B2 (en) * | 2000-11-27 | 2005-10-12 | 東洋紡績株式会社 | Sound absorbing material |
| JP3705419B2 (en) * | 2000-11-27 | 2005-10-12 | 東洋紡績株式会社 | Lightweight sound absorbing material |
| JP3701010B2 (en) * | 2001-01-23 | 2005-09-28 | 河西工業株式会社 | Insulator dash for automobile |
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| JP5092144B2 (en) * | 2008-05-29 | 2012-12-05 | 株式会社ケナテックス | Sound absorbing material and manufacturing method thereof |
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- 1997-01-27 JP JP02576897A patent/JP3632876B2/en not_active Expired - Fee Related
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