JP3654821B2 - Thermoformable core material and manufacturing method thereof - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、熱成形に適した熱成形性芯材及びその製造方法に関する。
【０００２】
【従来の技術】
従来、自動車などの車両の内装材、特に自動車の熱成形天井の基材には、無機繊維からなる熱成形性芯材が好適に使用されている。熱成形性芯材としては、軽量で、剛性、耐熱性、熱成形性、非通気性等の性能が優れていることが要求される。このような熱成形性芯材としては、例えば、特開平７−６０８８３号公報に、無機繊維及び熱可塑性樹脂繊維からなるマット状基材の少なくとも一面に耐熱剛性樹脂層を積層し、剛性、耐熱性等に優れるとともに、非通気性にも優れた熱成形性芯材が示されている。
【０００３】
しかしながら、上記熱成形性芯材は、その一面に不織布などの表面材が積層され、自動車用天井材とされるが、マット状基材の耐熱剛性樹脂層を形成した側に表面材を積層すると、自動車用天井材の吸音性が不足するといった問題があった。また、マット状基材の耐熱剛性樹脂層を形成していない側に表面材を積層しようとすると、マット状基材と表面材との間に接着剤又は熱活性樹脂が必要となるが、熱成形性芯材の製造途中或いは熱成形性芯材を熱成形する工程において加熱圧縮した際、接着剤又は熱活性樹脂がマット状基材に含浸してしまうため、熱成形性芯材と表面材との接着強度が不足し、接着不良、剥離等が生じ易く、深いプレス成形が困難であり、また、得られる自動車天井材が使用中の高温に対応できなくなるといった問題があった。
【０００４】
【発明が解決しようとする課題】
本発明の目的は、軽量で、剛性、耐熱性、熱賦形性、非通気性等に優れるとともに、吸音性にも優れ、自動車用天井材として好適に使用することのできる熱成形性芯材及びその製造方法を提供することにある。
【０００５】
【課題を解決するための手段】
本発明の熱成形性芯材は、耐熱性繊維が熱可塑性樹脂で相互に結着されてなるマット状基材の一面（以下、「表面」と記す）に、前記熱可塑性樹脂より溶融温度の高い耐熱剛性樹脂からなる耐熱剛性樹脂層と、熱活性樹脂からなる熱活性樹脂層とがこの順に積層され、かつ、該耐熱剛性樹脂層及び熱活性樹脂層に開口面積が５〜１００ｍｍ2 で且つマット状基材に連通した貫通孔が分散して形成されており、他面（以下、「裏面」と記す）に、前記熱可塑性樹脂より溶融温度の高い耐熱剛性樹脂からなる耐熱剛性樹脂層と、熱活性樹脂からなる熱活性樹脂層とがこの順に積層されてなることを特徴とする。
【０００６】
本発明で使用されるマット状基材は、耐熱性繊維が熱可塑性樹脂で相互に結着されてなり、全体にわたって空隙を有しているものであれば特には限定されず、また、耐熱性繊維に熱可塑性樹脂繊維が混抄されているものが好ましい。具体的には、例えば、耐熱性繊維からなるマット又は耐熱性繊維と熱可塑性樹脂繊維との混抄繊維からなるマットに熱可塑性樹脂を含浸させたもの、耐熱性繊維と熱可塑性樹脂繊維との混抄繊維からなるマットの熱可塑性樹脂繊維の一部又は全部を溶融させて耐熱性繊維を相互に結着させたもの、耐熱性繊維からなるマット又は耐熱性繊維と熱可塑性樹脂繊維との混抄繊維からなるマットに熱可塑性樹脂粉末を分散させ熱可塑性樹脂粉末の一部又は全部を溶融させて耐熱性繊維を相互に結着させたもの等が挙げられる。尚、マット状基材の空隙率は、小さくなると、得られる熱成形性芯材の吸音性及び軽量性が低下し、大きくなると、得られる熱成形性芯材の機械的強度が低下するので、適宜調整するのが好ましい。
【０００７】
上記耐熱性繊維としては、例えば、無機繊維、植物繊維等が挙げられ、得られる熱成形性芯材に要求される物性に応じて適宜選択するのが好ましく、混抄して使用してもよい。例えば、得られる熱成形性芯材の曲げ強度、厚さ回復性等の機械的強度が重視される場合には無機繊維を使用するのが好ましく、得られる熱成形性芯材のサーマルリサイクル性が重視される場合には植物繊維を使用するのが好ましい。
【０００８】
上記無機繊維としては、例えば、ガラス繊維、炭素繊維、ロックウール、セラミック繊維等が挙げられ、これらは単独で使用しても２種以上併用してもよい。無機繊維の長さは、短すぎても長すぎても、得られる熱成形性芯材の熱成形性が低下するので、５〜２５０ｍｍが好ましく、５０〜１５０ｍｍのものが７０重量％以上含有されているのがより好ましい。また、無機繊維の太さは、細くなると、得られる熱成形性芯材の曲げ強度、厚み回復性などの機械的強度が低下し、太くなると、得られる熱成形性芯材の軽量性が低下するので、その直径が５〜２０μｍであるのが好ましく、より好ましくは７〜１３μｍである。
【０００９】
上記植物繊維としては、例えば、ジュート繊維、ケナフ繊維等が挙げられ、これらは単独で使用しても２種以上併用してもよい。植物繊維の長さは、短すぎても長すぎても、得
られる熱成形性芯材の曲げ強度、厚み回復性などの機械的強度が低下するので、３〜２００ｍｍが好ましく、より好ましくは５〜１５０ｍｍである。また、植物繊維の太さは、その直径が２００μｍ以下のものが一般的であり、好ましくは１０〜１５０μｍである。
【００１０】
上記耐熱性繊維を相互に結着する熱可塑性樹脂としては、溶融状態で耐熱性繊維間に含浸し易く、かつ、耐熱性繊維と結着し易いものが好ましく、例えば、ポリエチレン、ポリプロピレン、ポリスチレン、エチレン−酢酸ビニル共重合体、飽和ポリエステル、これらの変性物等が挙げられる。
【００１１】
上記熱可塑性樹脂繊維としては、溶融時に上記耐熱性繊維と結着するものが好ましく、例えば、ポリエチレン、ポリプロピレン、ポリスチレン等からなる繊維が挙げられる。熱可塑性樹脂繊維の長さ及び太さは、上記耐熱性繊維に分散し易く、均一に混抄される程度が好ましい。具体的には、長さは５〜２００ｍｍが好ましく、より好ましくは２０〜１００ｍｍであり、太さは、直径が５〜７０μｍが好ましく、より好ましくは１５〜４０μｍである。
【００１２】
上記耐熱性繊維或いは耐熱性繊維と熱可塑性樹脂繊維との混抄繊維からなるマットを得る方法としては、従来公知の任意の方法が採用されてよく、例えば、カードマシンに耐熱性繊維と必要に応じて熱可塑性樹脂繊維を供給し、これらを解繊してマット状にした後、ニードルパンチを打つ方法が一般的である。ニードルパンチは、得られる熱成形性芯材の機械的強度を向上させるのに、１ｃｍ2 あたり２〜１００箇所打たれるのが好ましく、より好ましくは１ｃｍ2 あたり１０〜５０箇所である。
【００１３】
上記マット状基材中の耐熱性繊維と、熱可塑性樹脂（熱可塑性樹脂繊維を含む）の配合割合は、耐熱性繊維が少なくなると、得られる熱成形性芯材の耐熱性が低下し、多くなると、耐熱性繊維相互の結着力が低下し、得られる熱成形性芯材の剛性が低下するので、耐熱性繊維と熱可塑性樹脂が重量比で５：１〜１：５であるのが好ましい。
【００１４】
また、マット状基材の見掛け密度は、小さくなると、得られる熱成形性芯材の機械的強度が低下し、大きくなると、得られる熱成形性芯材の吸音性及び軽量性が低下するので、０．０１〜０．２ｇ／ｃｍ3 が好ましく、マット状基材の坪量は、小さくなると、得られる熱成形性芯材の機械的強度が低下し、大きくなると、得られる熱成形性芯材の軽量性が低下するので、２００〜１５００ｇ／ｍ2 が好ましく、より好ましくは３００〜８００ｇ／ｍ2 である。
【００１５】
上記マット状基材の表面には、このマット状基材に連通する貫通孔を有する、耐熱剛性樹脂層（以下、「耐熱剛性樹脂層（１）」と記す）及び熱活性樹脂層（以下、「熱活性樹脂層（１）」と記す）とがこの順に積層されている。
【００１６】
上記耐熱剛性樹脂層（１）を構成する耐熱剛性樹脂は、マット状基材中の熱可塑性樹脂より溶融温度の高いものであり、３０℃以上高いものが好ましく、５０℃以上高いものがより好ましい。これにより、後述するように、得られる熱成形性芯材全体を加熱して、該耐熱剛性樹脂以外の樹脂を溶融させることができる。このような耐熱剛性樹脂としては、例えば、ポリブチレンテレフタレート、ポリエチレンテレフタレート、ポリカーボネート、ポリアミド、これらの変性物等が挙げられる。
【００１７】
耐熱剛性樹脂層（１）の厚さは、薄くなると、熱成形性芯材の製造過程における加熱圧縮時、得られる熱成形性芯材の熱成形時などにマット状基材中の耐熱性繊維が耐熱剛性樹脂層（１）を突き破り易くなり、厚くなると、得られる熱成形性芯材の軽量性が低下するので、３〜２５μｍが好ましい。
【００１８】
上記熱活性樹脂層（１）を構成する熱活性樹脂は、その熱活性発現温度が上記耐熱剛性樹脂の溶融温度より低いものであり、２０℃以上低いものが好ましく、マット状基材中の熱可塑性樹脂の溶融温度と同程度であるのがより好ましい。これにより、得られる熱成形性芯材全体を加熱した際、耐熱剛性樹脂を溶融させることなく、表面の熱活性樹脂を溶融活性化することができるので、熱成形性芯材の製造途中或いは熱成形性芯材を熱成形する工程において加熱圧縮した際、熱活性樹脂がマット状基材に含浸してしまうことがなく、後述する表面材を強固に接着することができる。
【００１９】
このような熱活性樹脂としては、例えば、ポリエチレン、ポリプロピレン、エチレン−酢酸ビニル共重合体、飽和ポリエステル、変性ポリエチレン、共重合ポリアミド等が挙げられる。
【００２０】
熱活性樹脂のメルトフローレート（以下、「ＭＦＲ」と記す）は、小さくなると、後述する表面材を積層する際、熱活性樹脂を溶融活性化させても、熱活性樹脂が表面材内部に含浸せずアンカー効果が得られず、大きくなると、後述する表面材を積層する際、熱活性樹脂のほとんどが表面材内部に含浸してしまい、いずれの場合も表面材と熱活性樹脂層（１）との接着強度が低下するので、０．５〜２０が好ましく、より好ましくは２〜１５である。尚、上記ＭＦＲは、ＪＩＳ Ｋ ７２１０に準拠し、温度１９０℃、荷重２１．２Ｎで測定した値である。
【００２１】
熱活性樹脂層（１）の厚さは、薄くなると、後述する表面材を積層する際、表面材内部に含浸する熱活性樹脂の量が少なくなり、表面材と熱活性樹脂層（１）との接着強度が低下し、厚くなると、得られる熱成形性芯材の軽量性が低下し、また、後述する表面材を積層する際、表面材内部に含浸する熱活性樹脂の量が多くなり、表面材の風合が固くなるので、２０〜１００μｍが好ましい。
【００２２】
上記貫通孔の大きさは、小さくなると、得られる熱成形性芯材の吸音性が低下し、大きくなると、熱活性樹脂層（１）と後述する表面材との接着強度が低下するので、貫通孔１つの開口面積が３〜１００ｍｍ2 に限定され、好ましくは１２〜５０ｍｍ2 である。貫通孔の形成割合は、少なくなると、得られる熱成形性芯材の吸音性が低下し、多くなると、得られる熱成形性芯材の曲げ強度や熱活性樹脂層と後述する表面材との接着強度が低下するので、開口面積合計が、マット状基材一面の面積に対して５〜８０％であるのが好ましく、より好ましくは１０〜３０％であり、全体に均一に分散して形成されているのが好ましい。
【００２３】
また、貫通孔の形状は特には限定されないが、形成が容易であるので、開口形状が円形であるのが好ましく、規則的に形成されているのが、後述する表面材を接着した際、外観を損なうことがないので、より好ましい。貫通孔の開口形状が円形である場合、その直径は、２〜１５ｍｍが好ましく、より好ましくは４〜８ｍｍであり、異なる大きさの貫通孔を組み合わせてもよい。
【００２４】
貫通孔は、耐熱剛性樹脂層（１）及び熱活性樹脂層（１）を積層した後に形成するのが、形成が容易であるとともに、貫通孔形成割合などが調整し易いので好ましい。貫通孔を形成する方法としては、例えば、耐熱剛性樹脂層（１）及び熱活性樹脂層（１）とその他必要に応じて積層された各層からなる積層シートを、凹部を有するダイスと凸部を有するダイスとの間に供給し、前記凸部により積層シートを打ち抜く機械的パンチング法、前記積層シートを、耐熱剛性樹脂層（１）を構成する耐熱剛性樹脂の溶融温度以上に加熱し、ロッドが埋め込まれたロールと通常のロールとの間に該積層シートを供給し、溶融開口する方法、前記積層シートにレーザー光線を照射し、溶融開口する方法等が挙げられ、中でも機械的パンチング法が、任意の大きさの貫通孔を精度よく安定的に形成することができるので好ましい。
【００２５】
上記マット状基材の裏面には、耐熱剛性樹脂層（以下、「耐熱剛性樹脂層（２）」と記す）と、熱活性樹脂層（以下、「熱活性樹脂層（２）」と記す）とがこの順に積層されている。
【００２６】
上記耐熱剛性樹脂層（２）を構成する耐熱剛性樹脂は、表面の耐熱剛性樹脂層（１）を構成する耐熱剛性樹脂と同様ものが挙げられる。耐熱剛性樹脂層（２）の厚さは、薄くなると、熱成形性芯材の製造過程における加熱圧縮時、得られる熱成形性芯材の熱成形時などにマット状基材中の耐熱性繊維が耐熱剛性樹脂層（２）を突き破り易くなるため、非通気性が低下し、厚くなると、得られる熱成形性芯材の軽量性が低下するので、３〜２５μｍが好ましい。
【００２７】
上記熱活性樹脂層（２）を構成する熱活性樹脂は、表面の熱活性樹脂層（１）を構成する熱活性樹脂と同様のものが挙げられ、これにより、得られる熱成形性芯材全体を加熱した際、耐熱剛性樹脂を溶融させることなく、裏面の熱活性樹脂を溶融活性化することができるので、自動車用天井材等の成形品の通気遮断性を損なうことなく、部材等に強固に熱接着することができる。尚、熱成形性芯材を部材等に固定する必要がない場合は、熱活性樹脂層（２）のＭＦＲ等が上記範囲外のものでも好ましく使用される。熱活性樹脂層（２）の厚さは、２０〜１００μｍが好ましい。
【００２８】
また、上記熱成形性芯材に積層された耐熱剛性樹脂及び熱活性樹脂は、表面と裏面とで同一であってもよく、異なっていてもよい。また、耐熱剛性樹脂層及び熱活性樹脂層の厚さも、表面と裏面とで同一であってもよく、異なっていてもよい。
【００２９】
本発明の熱成形性芯材の製造方法としては、例えば、以下の方法が挙げられる。第１の方法としては、熱可塑性樹脂、耐熱剛性樹脂及び熱活性樹脂をこの順に積層してなる積層シートを２枚作成し、２枚の積層シートのうち１枚に貫通孔を形成し、耐熱性繊維からなるマット或いは耐熱性繊維と熱可塑性樹脂繊維との混抄繊維からなるマットの両面に、各積層シートの熱可塑性樹脂層がマット側になるように配置し、耐熱剛性樹脂の溶融温度以下の温度に加熱して、熱可塑性樹脂及び熱活性樹脂を溶融させるとともに全体を厚さ方向に圧縮し、耐熱剛性樹脂及びその外側にある熱活性樹脂をマット内に含浸させることなく、マット両面の熱可塑性樹脂をマット内に含浸させた後、厚さ方向に拡開させる方法が挙げられる。
【００３０】
また、第２の方法としては、耐熱性繊維からなるマット或いは耐熱性繊維と熱可塑性樹脂繊維との混抄繊維からなるマットの両面に熱可塑性樹脂を積層しておき、一方で、耐熱剛性樹脂及び熱活性樹脂を積層してなる積層シートを２枚作成し、２枚の積層シートのうち１枚に貫通孔を形成し、マットに積層した熱可塑性樹脂層面に、各積層シートの耐熱剛性樹脂層が熱可塑性樹脂層側になるように配置し、耐熱剛性樹脂の溶融温度以下の温度に加熱して、熱可塑性樹脂及び熱活性樹脂を溶融させるとともに全体を厚さ方向に圧縮し、耐熱剛性樹脂及びその外側にある熱活性樹脂をマット内に含浸させることなく、マット両面の熱可塑性樹脂をマット内に含浸させた後、厚さ方向に拡開させる方法が挙げられる。
【００３１】
上記製造方法において、マット両面の熱可塑性樹脂はマット内に含浸し、マットの耐熱性繊維を相互に結着する。含浸工程において、熱可塑性樹脂全てをマット内に含浸させる必要はなく、一部は含浸させずに残しておいてもよい。そうすることにより、マットと耐熱剛性樹脂層との接着強度、得られる熱成形性芯材の機械的強度等を向上させることができる。上記第１の方法は、マット両面の熱可塑性樹脂の一部を含浸させずに残しておいても、表面の熱可塑性樹脂層に貫通孔が形成されているので、得られる熱成形性芯材の吸音性を損なうことがなく、好ましい。
【００３２】
マット両面の熱可塑性樹脂層の厚さは、薄くなると、マット内に含浸しても耐熱性繊維相互の結着力が不足し、得られる熱成形性芯材の機械的強度が低下し、厚くなると、得られる熱成形性芯材の軽量性が低下するので、５０〜５００μｍが好ましく、より好ましくは７０〜３００μｍである。
【００３３】
上記熱可塑性樹脂、耐熱剛性樹脂及び熱活性樹脂からなる積層シート、又は、耐熱剛性樹脂及び熱活性樹脂からなる積層シートを得る方法としては、特には限定されず、従来公知の任意の方法が採用されてよく、例えば、共押出法、押出ラミネート法、ドライラミネート法等が挙げられる。中でも、各層を構成する樹脂をダイ内に同時押出した後、Ｔダイ等から吐出させる共押出法が、経済的であり、好ましい。
【００３４】
また、マットの両面に熱可塑性樹脂を積層する方法としては、特には限定されず、従来公知の任意の方法が採用されてよく、例えば、マットに熱可塑性樹脂を押出ラミネートする方法、熱可塑性樹脂からなるフィルムをマットに熱ラミネートする方法等が挙げられる。
【００３５】
上記圧縮の条件は特には限定されず、適宜決定してよいが、圧縮圧力が０．２〜１ＭＰａであり、圧縮時間が２〜１０秒であるのが好ましい。
【００３６】
上記拡開の方法としては、耐熱性繊維の弾力で自然回復させてもよく、強制的に回復させてもよい。強制的に回復させる方法としては、例えば、テフロン（登録商標）コーティングされた鋼板やガラスクロスシートなどでマット全体を挟み、その両表面を真空吸引する方法が挙げられる。拡開の程度は、得られる熱成形性芯材の所望の空隙率、見掛け密度等により、適宜調整するのが好ましい。
【００３７】
上記製造方法により得られた熱成形性芯材は、従来公知の任意の方法により冷却される。冷却は自然冷却又は強制冷却のいずれでもよいが、冷却速度、生産性、冷却による熱可塑性樹脂の硬化の安定性等が調整し易いので、強制冷却が好ましい。また、拡開の後に冷却しても、拡開と冷却とを略同時に行ってもよい。
【００３８】
上記熱成形性芯材は、その貫通孔を有する熱活性樹脂層面に、表面材が積層され、熱成形されて自動車用天井材となされる。表面材の積層一体化は、熱成形性芯材の熱成形時に同時に行ってもよく、熱成形の前に行ってもよい。上記表面材としては、例えば、天然繊維、合成繊維、これらの混抄繊維等からなる不織布が好適に使用される。天然繊維としては、例えば、綿、羊毛、麻等が挙げられ、合成繊維としては、例えば、ポリエステル、ポリアミド、ポリウレタン等が挙げられる。
【００３９】
表面材として不織布を使用することにより、熱成形性芯材表面の熱活性樹脂の一部が表面材内部に含浸されるので、アンカー効果により、熱活性樹脂層と表面材との接着強度が優れたものとなる。
【００４０】
熱成形性芯材に表面材を積層する方法としては、例えば、熱成形性芯材の熱活性樹脂層面に表面材を重ね、加熱状態にてプレスする方法が挙げられる。また、熱活性樹脂層と表面材との間に接着性熱可塑性樹脂層を形成してもよい。
【００４１】
【発明の実施の形態】
以下に実施例を掲げて本発明の態様を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。
【００４２】
（実施例１）
長さ４０〜７５ｍｍ、直径９μｍのガラス繊維と、長さ６４ｍｍ、太さ３５μｍ、溶融温度１６２℃のポリプロピレン繊維とを、重量比が３：２となるように混合し、カードマシンに供給して、混抄繊維をマット状とし、２０箇所／ｃｍ2 でニードルパンチを打ち、坪量約５５０ｇ／ｃｍ2 、厚さ約７．５ｍｍの混抄マットを得た。得られた混抄マットの両面に、溶融温度１３５℃、ＭＦＲ７の、少量の無水マレイン酸変性ポリエチレンを含有する高密度ポリエチレンからなる厚さ１２０μｍの高密度ポリエチレンフィルムを積層し、３層マットを得た。
【００４３】
一方、溶融温度２３０℃の６−ナイロンと、溶融温度１２５℃、ＭＦＲ１０のマレイン酸変性直鎖状低密度ポリエチレンとを共押出し、２枚の２層フィルムを得た。２枚の２層フィルムはいずれも６−ナイロン層の厚さが２０μｍ、マレイン酸変性直鎖状低密度ポリエチレン層の厚さが６０μｍであった。得られた２層フィルムのうち１枚に、開口面積２８ｍｍ2 （開口形状は直径６ｍｍの円）の貫通孔を１０ｍｍ間隔でパンチングにより打ち抜いた。
【００４４】
次に、上記３層マットの一面に上記貫通孔が形成された２層フィルムを、他面にもう１枚の２層フィルムを、それぞれ６−ナイロン層側が３層マットに接するように積層し、坪量約８５０ｇ／ｍ2 、厚さ約８ｍｍの７層マットを得た。
【００４５】
得られた７層マットを、テフロンコーティングされたガラスクロスシートの間に挟み、約２００℃の熱風式加熱炉に供給し、５分間放置した。その後、７層マットをガラスクロスシートで挟んだまま平板プレスに移し、厚さが１ｍｍになるまで圧縮して、圧縮状態で５秒間保持した後、平板プレスから取り外し、両面のガラスクロスシート側から真空吸引して、厚さ方向に０．５ｍｍ／秒で引っ張り、厚さ５．５ｍｍになるまで拡開した。この拡開状態で３分間空冷した後にガラスクロスシートを取り除き、熱成形性芯材を得た。得られた熱成形性芯材は、厚さ約５．０ｍｍ、坪量約８５０ｇ／ｍ2 で、貫通孔の開口面積合計は、マット状基材一面の面積に対して約２８％であり、上記７層マットの高密度ポリエチレンフィルムは、そのほとんどが混抄マット内に含浸していたが、６−ナイロン層は含浸していなかった。
【００４６】
図１は、得られた熱成形性芯材を示した断面模式図であり、熱成形性芯材１は、混抄マットに高密度ポリエチレンフィルムが含浸してなるマット状基材２の表面に、貫通孔３が形成された６−ナイロン層４及びマレイン酸変性直鎖状低密度ポリエチレン層５がこの順に積層一体化され、裏面に、貫通孔が形成されず、非通気性の６−ナイロン層６及びマレイン酸変性直鎖状低密度ポリエチレン層７がこの順に積層一体化されてなる。
【００４７】
（実施例２）
溶融温度１３５℃、ＭＦＲ７の、少量の無水マレイン酸変性ポリエチレンを含有する高密度ポリエチレンと、溶融温度２３０℃の６−ナイロンと、溶融温度８０〜１１５℃の共重合ポリアミドとをこの順に共押出し、２枚の３層フィルムを得た。２枚の３層フィルムはいずれも高密度ポリエチレン層の厚さが１２０μｍ、６−ナイロン層の厚さが２０μｍ、共重合ポリアミド層の厚さが６０μｍであった。得られた３層フィルムのうち１枚に、開口面積２８ｍｍ2 （開口形状は直径６ｍｍの円）の貫通孔を１０ｍｍ間隔でパンチングにより打ち抜いた。
【００４８】
次に、実施例１と同様の混抄マットの一面に上記貫通孔が形成された３層フィルムを、他面にもう１枚の３層フィルムを、それぞれ高密度ポリエチレン層側が混抄マットに接するように積層し、坪量約８５０ｇ／ｍ2 、厚さ約８ｍｍの７層マットを得た。得られた７層マットから、実施例１と同様にして熱成形性芯材を得た。得られた熱成形性芯材は、厚さ約５．０ｍｍ、坪量約８５０ｇ／ｍ2 で、貫通孔の開口面積合計は、マット状基材一面の面積に対して約２８％であり、上記７層マットの高密度ポリエチレン層は、そのほとんどが混抄マット内に含浸していたが、６―ナイロン層は含浸していなかった。
【００４９】
（比較例１）
実施例１と同様の混抄マットの両面に、溶融温度１３５℃、ＭＦＲ７の、少量の無水マレイン酸変性ポリエチレンを含有する高密度ポリエチレンからなる厚さ１００μｍの高密度ポリエチレンフィルムを積層し、３層マットを得た。
【００５０】
一方、溶融温度１３５℃、ＭＦＲ２の、少量の無水マレイン酸変性ポリエチレンを含有する高密度ポリエチレンと、溶融温度１２５℃、ＭＦＲ１０のマレイン酸変性直鎖状低密度ポリエチレンとを共押出し、２枚の２層フィルムを得た。２枚の２層フィルムはいずれも高密度ポリエチレン層の厚さが１３０μｍ、マレイン酸変性直鎖状低密度ポリエチレン層の厚さが６０μｍであった。
【００５１】
次に、上記３層マットの両面に上記２層フィルムを、それぞれ高密度ポリエチレン層側が３層マットに接するように積層し、坪量約９２０ｇ／ｍ2 、厚さ約８．３ｍｍの７層マットを得た。得られた７層マットから、実施例１と同様にして熱成形性芯材を得た。得られた熱成形性芯材は、厚さ約５．０ｍｍ、坪量約９２０ｇ／ｍ2 であり、上記７層マットの高密度ポリエチレンフィルムは、そのほとんどが混抄マット内に含浸しており、その上の高密度ポリエチレン層及びマレイン酸変性直鎖状低密度ポリエチレン層も１部含浸していた。
【００５２】
自動車用天井材の作成
実施例及び比較例で得られた熱成形性芯材の、実施例１及び２については貫通孔が形成された面に、比較例１についてはその一面に、ポリエステル繊維からなる坪量約２００ｇ／ｍ2 の不織布を配置し、周縁８箇所をホッチキスで仮固定した。次に、遠赤外線ヒーター式加熱炉により、不織布の表面温度が約１９０℃、その反対側の表面温度が約１８０℃になるように加熱して、常温状態のプレス機に移した後、プレス成形するとともに熱成形性芯材と不織布とを積層一体化し、この状態で２０秒間保持した後、プレス機から取り出し、自動車用天井材を得た。
【００５３】
表面材と熱成形性芯材の接着強度の評価得られた自動車用天井材のフラット部位から四角形の試料を切り出し、その一角の不織布を把持し、熱成形性芯材から不織布を９０°剥離して、その結果を表１に示した。
○：熱成形性芯材と不織布との接着強度が強く、不織布が材料破壊した。
×：熱成形性芯材と不織布との間で剥離した。
【００５４】
自動車用天井材の吸音性の評価
得られた自動車用天井材の不織布側からの吸音特性を、ＪＩＳ Ａ １４０５に準拠して測定し、２．５ｋＨｚ、４ｋＨｚ及び６．３ｋＨｚでの吸音率を表１に示した。
【００５５】
自動車用天井材の非通気性の評価
得られた自動車用天井材のフラット部位の透気度（ｃｍ3 ／ｃｍ2 ・秒）を、デンソメータにより測定し、その値を表１に示した。
【００５６】
【表１】
【発明の効果】
本発明の熱成形性芯材は、軽量で、剛性、耐熱性、熱賦形性に優れるとともに、裏面に、製造過程、熱成形過程において溶融しない耐熱剛性樹脂層を有しているので、非通気性にも優れている。さらに、表面側からの音は熱成形性芯材の貫通孔を通じて多孔質体であるマット状基材に到達するので、効果的に音を減衰させることができ、優れた吸音性を有している。また、表面にも、製造過程、熱成形過程において溶融しない耐熱剛性樹脂層が形成されているので、表面材を接着するための熱活性樹脂層がマット状基材に含浸してしまうことがなく、表面材との接着強度を損なうことがない。本発明の熱成形性芯材は、上記の通りの構成であるので、特に自動車用天井材として好適に使用することができる。
【図面の簡単な説明】
【図１】 実施例１で得られた本発明の熱成形性芯材の断面模式図である。
【符号の説明】
１ 熱成形性芯材
２ マット状基材
３ 貫通孔
４、６ ６−ナイロン層
５、７ マレイン酸変性直鎖状低密度ポリエチレン層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoformable core material suitable for thermoforming and The manufacturing method About.
[0002]
[Prior art]
Conventionally, a thermoformable core material made of inorganic fibers is suitably used as an interior material of a vehicle such as an automobile, particularly a base material of a thermoformed ceiling of an automobile. The thermoformable core material is required to be lightweight and have excellent performance such as rigidity, heat resistance, thermoformability, and air permeability. As such a thermoformable core material, for example, in JP-A-7-60883, a heat-resistant and rigid resin layer is laminated on at least one surface of a mat-like substrate made of inorganic fibers and thermoplastic resin fibers, thereby providing rigidity and heat resistance. A thermoformable core material having excellent properties and the like and also having excellent air permeability is shown.
[0003]
However, the thermoformable core material is laminated with a surface material such as a non-woven fabric on one surface thereof, and is used as an automobile ceiling material. When the surface material is laminated on the side where the heat-resistant rigid resin layer of the mat-like substrate is formed, There was a problem that the sound absorbing property of the ceiling material for automobiles was insufficient. Further, if a surface material is to be laminated on the side of the mat-like base material on which the heat-resistant rigid resin layer is not formed, an adhesive or a thermoactive resin is required between the mat-like base material and the surface material. Since the mat or base material is impregnated with the adhesive or the thermoactive resin during the production of the moldable core material or in the process of thermoforming the thermoformable core material, the thermoformable core material and the surface material Inadequate adhesive strength, adhesion failure, peeling, etc. are likely to occur, deep press molding is difficult, and the resulting automotive ceiling material cannot cope with high temperatures during use.
[0004]
[Problems to be solved by the invention]
An object of the present invention is a thermoformable core material that is lightweight, excellent in rigidity, heat resistance, thermal formability, air permeability, etc., and excellent in sound absorption, and can be suitably used as a ceiling material for automobiles. And its manufacturing method There is.
[0005]
[Means for Solving the Problems]
The thermoformable core material of the present invention has a melting temperature higher than that of the thermoplastic resin on one surface (hereinafter referred to as “surface”) in which heat-resistant fibers are bonded to each other with a thermoplastic resin. A heat-resistant rigid resin layer made of a high heat-resistant rigid resin and a heat-activated resin layer made of a thermally active resin are laminated in this order, and the opening area is 5 to 100 mm in the heat-resistant rigid resin layer and the thermally active resin layer. 2 so And communicated with the mat-like substrate. Through holes are formed in a dispersed manner, on the other side (hereinafter referred to as “back side”), a heat-resistant rigid resin layer made of a heat-resistant rigid resin having a melting temperature higher than that of the thermoplastic resin, and heat made of a thermally active resin. The active resin layer is laminated in this order.
[0006]
The mat-like substrate used in the present invention is not particularly limited as long as the heat-resistant fibers are bonded to each other with a thermoplastic resin and have voids throughout, and the heat-resistant fibers are not limited. A fiber in which a thermoplastic resin fiber is mixed is preferable. Specifically, for example, a mat made of heat-resistant fibers or a mat made of mixed fibers of heat-resistant fibers and thermoplastic resin fibers impregnated with a thermoplastic resin, or a mixed paper of heat-resistant fibers and thermoplastic resin fibers. A material in which part or all of a thermoplastic resin fiber of a mat made of fiber is melted and heat-resistant fibers are bonded to each other, a mat made of heat-resistant fiber or a mixed fiber of heat-resistant fiber and thermoplastic resin fiber And the like, in which a thermoplastic resin powder is dispersed in the resulting mat, a part or all of the thermoplastic resin powder is melted, and heat-resistant fibers are bonded to each other. In addition, since the porosity of the mat-shaped substrate is reduced, the sound-absorbing property and lightness of the obtained thermoformable core material are reduced, and when it is increased, the mechanical strength of the obtained thermoformable core material is reduced. It is preferable to adjust appropriately.
[0007]
Examples of the heat-resistant fiber include inorganic fibers and plant fibers, and it is preferable to select them appropriately according to the physical properties required for the thermoformable core material to be obtained. For example, it is preferable to use inorganic fibers when mechanical strength such as bending strength and thickness recoverability of the obtained thermoformable core material is important, and the thermal recyclability of the obtained thermoformable core material is When importance is attached, it is preferable to use a vegetable fiber.
[0008]
As said inorganic fiber, glass fiber, carbon fiber, rock wool, ceramic fiber etc. are mentioned, for example, These may be used individually or may be used together 2 or more types. If the length of the inorganic fiber is too short or too long, the thermoformability of the resulting thermoformable core material is lowered, so that it is preferably 5 to 250 mm, and those containing 50 to 150 mm are contained in an amount of 70% by weight or more. More preferably. In addition, when the thickness of the inorganic fiber is reduced, the mechanical strength such as bending strength and thickness recoverability of the thermoformable core material obtained is reduced, and when the thickness is increased, the lightness of the obtained thermoformable core material is reduced. Therefore, the diameter is preferably 5 to 20 μm, more preferably 7 to 13 μm.
[0009]
As said plant fiber, a jute fiber, a kenaf fiber, etc. are mentioned, for example, These may be used individually or may be used together 2 or more types. The length of the plant fiber can be either too short or too long.
Since the mechanical strength such as bending strength and thickness recoverability of the thermoformable core material to be obtained is lowered, it is preferably 3 to 200 mm, more preferably 5 to 150 mm. Further, the thickness of the plant fiber is generally 200 μm or less, preferably 10 to 150 μm.
[0010]
As the thermoplastic resin that binds the heat-resistant fibers to each other, those that are easily impregnated between the heat-resistant fibers in a molten state and that are easily bonded to the heat-resistant fibers are preferable. For example, polyethylene, polypropylene, polystyrene, Examples include ethylene-vinyl acetate copolymer, saturated polyester, and modified products thereof.
[0011]
The thermoplastic resin fiber is preferably one that binds to the heat-resistant fiber when melted, and examples thereof include fibers made of polyethylene, polypropylene, polystyrene, and the like. The length and thickness of the thermoplastic resin fibers are preferably such that the thermoplastic resin fibers are easily dispersed in the heat-resistant fibers and are uniformly mixed. Specifically, the length is preferably from 5 to 200 mm, more preferably from 20 to 100 mm, and the thickness is preferably from 5 to 70 μm in diameter, more preferably from 15 to 40 μm.
[0012]
As a method of obtaining a mat composed of the heat-resistant fiber or a mixed fiber of heat-resistant fiber and thermoplastic resin fiber, any conventionally known method may be employed. For example, the card machine may include a heat-resistant fiber and, if necessary, a card machine. In general, a method of supplying a thermoplastic resin fiber, defibrating these to form a mat, and then hitting a needle punch is generally used. Needle punch is 1cm to improve the mechanical strength of the thermoformable core material obtained. 2 It is preferable to hit 2 to 100 points per, more preferably 1 cm 2 It is 10-50 places per.
[0013]
The blending ratio of the heat-resistant fiber and the thermoplastic resin (including the thermoplastic resin fiber) in the mat-shaped base material decreases the heat resistance of the thermoformable core material obtained when the heat-resistant fiber is reduced. Then, the binding force between the heat-resistant fibers decreases, and the rigidity of the resulting thermoformable core material decreases. Therefore, the weight ratio of the heat-resistant fibers and the thermoplastic resin is preferably 5: 1 to 1: 5. .
[0014]
Further, when the apparent density of the mat-like base material is reduced, the mechanical strength of the obtained thermoformable core material is reduced, and when it is increased, the sound absorption and lightness of the obtained thermoformable core material are reduced. 0.01-0.2 g / cm Three When the basis weight of the mat-like base material is small, the mechanical strength of the resulting thermoformable core material is reduced. 1500g / m 2 Is more preferable, more preferably 300 to 800 g / m 2 It is.
[0015]
On the surface of the mat-like substrate, Communicate with this mat substrate A heat-resistant rigid resin layer (hereinafter referred to as “heat-resistant rigid resin layer (1)”) and a thermally active resin layer (hereinafter referred to as “thermally active resin layer (1)”) having through holes are laminated in this order. ing.
[0016]
The heat-resistant rigid resin constituting the heat-resistant rigid resin layer (1) has a melting temperature higher than that of the thermoplastic resin in the mat-like substrate, preferably higher by 30 ° C., more preferably higher by 50 ° C. . Thereby, as will be described later, the entire thermoformable core material obtained can be heated and a resin other than the heat-resistant rigid resin can be melted. Examples of such a heat-resistant rigid resin include polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polyamide, and modified products thereof.
[0017]
When the thickness of the heat-resistant rigid resin layer (1) is reduced, the heat-resistant fibers in the mat-like base material are heated at the time of heat compression in the production process of the thermoformable core material or at the time of thermoforming the obtained thermoformable core material. However, since it becomes easy to break through the heat-resistant rigid resin layer (1) and becomes thicker, the lightness of the resulting thermoformable core material decreases, so 3 to 25 μm is preferable.
[0018]
The thermoactive resin constituting the thermoactive resin layer (1) has a thermal activity expression temperature lower than the melting temperature of the heat-resistant rigid resin, and is preferably lower by 20 ° C. or more. More preferably, it is about the same as the melting temperature of the plastic resin. As a result, when the entire thermoformable core material obtained is heated, the heat-activatable resin on the surface can be melt-activated without melting the heat-resistant rigid resin. When the moldable core material is heated and compressed in the step of thermoforming, the matte base material is not impregnated with the thermoactive resin, and the surface material described later can be firmly bonded.
[0019]
Examples of such a thermally active resin include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, saturated polyester, modified polyethylene, and copolymerized polyamide.
[0020]
When the melt flow rate (hereinafter referred to as “MFR”) of the thermoactive resin is reduced, the thermoactive resin is impregnated inside the surface material even when the heat-active resin is melt-activated when the surface material described later is laminated. If the anchor effect cannot be obtained without increasing the thickness, when the surface material described later is laminated, most of the thermally active resin is impregnated inside the surface material. In any case, the surface material and the thermally active resin layer (1) Therefore, 0.5-20 are preferable, and 2-15 are more preferable. The MFR is a value measured according to JIS K 7210 at a temperature of 190 ° C. and a load of 21.2 N.
[0021]
When the thickness of the thermal active resin layer (1) is reduced, the amount of the thermal active resin impregnated inside the surface material is reduced when laminating the surface material described later, and the surface material and the thermal active resin layer (1) When the adhesive strength is reduced and thickened, the lightness of the thermoformable core material obtained is reduced, and when laminating the surface material described later, the amount of the thermally active resin impregnated inside the surface material increases, Since the texture of the surface material becomes hard, 20 to 100 μm is preferable.
[0022]
If the size of the through-hole is reduced, the sound absorbing property of the resulting thermoformable core material is reduced. If the size is increased, the adhesive strength between the thermoactive resin layer (1) and the surface material described later is reduced. Opening area of one hole is 3-100mm 2 Limited to, preferably 12-50 mm 2 It is. If the formation ratio of the through-holes decreases, the sound absorbability of the resulting thermoformable core material decreases, and if it increases, the bending strength of the obtained thermoformable core material or adhesion between the thermoactive resin layer and the surface material described later Since the strength decreases, the total opening area is preferably 5 to 80%, more preferably 10 to 30% with respect to the area of the entire surface of the mat-like base material. It is preferable.
[0023]
Further, the shape of the through hole is not particularly limited, but since the formation is easy, the opening shape is preferably circular, and the regular shape is formed when the surface material described later is adhered. It is more preferable because it does not impair. When the opening shape of the through hole is circular, the diameter is preferably 2 to 15 mm, more preferably 4 to 8 mm, and through holes of different sizes may be combined.
[0024]
The through-hole is preferably formed after the heat-resistant rigid resin layer (1) and the thermally active resin layer (1) are laminated because the formation is easy and the through-hole formation ratio is easily adjusted. As a method of forming the through-hole, for example, a heat-resistant rigid resin layer (1) and a heat-activated resin layer (1) and other laminated sheets made up of each layer as necessary, a die having a concave portion and a convex portion are used. A mechanical punching method in which the laminated sheet is punched out by the convex portion, the laminated sheet is heated to a temperature equal to or higher than the melting temperature of the heat-resistant rigid resin constituting the heat-resistant rigid resin layer (1), Examples include a method of supplying the laminated sheet between an embedded roll and a normal roll and melting and opening, a method of irradiating the laminated sheet with a laser beam and melting and opening, and a mechanical punching method is optional. This is preferable because a through hole having a size of can be accurately and stably formed.
[0025]
On the back surface of the mat-like substrate, a heat-resistant rigid resin layer (hereinafter referred to as “heat-resistant rigid resin layer (2)”) and a heat-activated resin layer (hereinafter referred to as “heat-activated resin layer (2)”) Are stacked in this order.
[0026]
Examples of the heat-resistant rigid resin constituting the heat-resistant rigid resin layer (2) include the same heat-resistant rigid resins as those constituting the heat-resistant rigid resin layer (1) on the surface. When the thickness of the heat-resistant rigid resin layer (2) is reduced, the heat-resistant fibers in the mat-like base material are heated at the time of heat compression in the production process of the thermoformable core material or at the time of thermoforming the obtained thermoformable core material. However, when the heat-resistant rigid resin layer (2) is easily pierced, the non-breathability is reduced, and when the thickness is increased, the lightweight property of the resulting thermoformable core material is reduced, so 3 to 25 μm is preferable.
[0027]
Examples of the thermoactive resin constituting the thermoactive resin layer (2) are the same as those of the thermoactive resin constituting the thermoactive resin layer (1) on the surface, and thus the entire thermoformable core material obtained. The heat-activatable resin on the back surface can be melt-activated without melting the heat-resistant rigid resin when heated, so it is strong to the member without impairing the air-blocking property of molded products such as automotive ceiling materials. Can be heat bonded. In addition, when it is not necessary to fix a thermoformable core material to a member etc., even if MFR etc. of a thermoactive resin layer (2) are outside the said range, it is used preferably. The thickness of the thermoactive resin layer (2) is preferably 20 to 100 μm.
[0028]
Further, the heat-resistant rigid resin and the thermoactive resin laminated on the thermoformable core material may be the same or different on the front surface and the back surface. Moreover, the thickness of the heat-resistant rigid resin layer and the thermally activated resin layer may be the same or different on the front surface and the back surface.
[0029]
Examples of the method for producing the thermoformable core material of the present invention include the following methods. As a first method, two laminated sheets obtained by laminating a thermoplastic resin, a heat-resistant rigid resin, and a thermoactive resin in this order are prepared, and a through-hole is formed in one of the two laminated sheets. Placed on both sides of the mat made of heat-resistant fibers or the mat made of mixed fibers of heat-resistant fibers and thermoplastic resin fibers, with the thermoplastic resin layer of each laminated sheet facing the mat, and below the melting temperature of the heat-resistant rigid resin The thermoplastic resin and the thermoactive resin are melted and the whole is compressed in the thickness direction, so that the heat resistant rigid resin and the thermoactive resin on the outside of the mat are not impregnated in the mat. An example is a method in which a thermoplastic resin is impregnated in a mat and then spread in the thickness direction.
[0030]
As a second method, a thermoplastic resin is laminated on both surfaces of a mat made of heat resistant fibers or a mat made of mixed fibers of heat resistant fibers and thermoplastic resin fibers. Two laminated sheets made by laminating thermoactive resins are prepared, through holes are formed in one of the two laminated sheets, and the heat-resistant rigid resin layer of each laminated sheet is formed on the surface of the thermoplastic resin layer laminated on the mat. Placed on the side of the thermoplastic resin layer, heated to a temperature below the melting temperature of the heat-resistant rigid resin, melts the thermoplastic resin and the thermoactive resin and compresses the whole in the thickness direction, and heat-resistant rigid resin In addition, there is a method of impregnating the mat with a thermoplastic resin on both sides of the mat without impregnating the mat with the thermoactive resin on the outside thereof, and then expanding in the thickness direction.
[0031]
In the above manufacturing method, the thermoplastic resin on both sides of the mat is impregnated in the mat, and the heat-resistant fibers of the mat are bound to each other. In the impregnation step, it is not necessary to impregnate the entire thermoplastic resin into the mat, and a part of the thermoplastic resin may be left without being impregnated. By doing so, the adhesive strength between the mat and the heat-resistant rigid resin layer, the mechanical strength of the resulting thermoformable core material, and the like can be improved. In the first method, even if a part of the thermoplastic resin on both sides of the mat is left without being impregnated, a through-hole is formed in the thermoplastic resin layer on the surface. This is preferable without impairing the sound absorption.
[0032]
If the thickness of the thermoplastic resin layer on both sides of the mat is reduced, the binding strength between the heat-resistant fibers will be insufficient even if impregnated in the mat, and the mechanical strength of the resulting thermoformable core will decrease and become thicker. Since the lightweight property of the obtained thermoformable core material is reduced, 50 to 500 μm is preferable, and 70 to 300 μm is more preferable.
[0033]
The method for obtaining the laminated sheet composed of the thermoplastic resin, the heat-resistant rigid resin and the thermally active resin, or the laminated sheet composed of the heat-resistant rigid resin and the thermally active resin is not particularly limited, and any conventionally known method is adopted. For example, a co-extrusion method, an extrusion laminating method, a dry laminating method and the like can be mentioned. Among them, the coextrusion method in which the resin constituting each layer is simultaneously extruded into a die and then discharged from a T die or the like is economical and preferable.
[0034]
Further, the method for laminating the thermoplastic resin on both sides of the mat is not particularly limited, and any conventionally known method may be employed. For example, a method of extruding and laminating a thermoplastic resin to the mat, a thermoplastic resin And a method of thermally laminating a film made of
[0035]
The compression conditions are not particularly limited and may be determined as appropriate. However, the compression pressure is preferably 0.2 to 1 MPa, and the compression time is preferably 2 to 10 seconds.
[0036]
As the expansion method, natural recovery may be performed by the elasticity of the heat resistant fiber, or forced recovery may be performed. As a method for forcibly recovering, for example, there is a method in which the entire mat is sandwiched between Teflon (registered trademark) -coated steel sheets or glass cloth sheets, and both surfaces are vacuum-sucked. The degree of expansion is preferably adjusted as appropriate depending on the desired porosity, apparent density, and the like of the resulting thermoformable core material.
[0037]
The thermoformable core material obtained by the above production method is cooled by any conventionally known method. Cooling may be either natural cooling or forced cooling, but forced cooling is preferable because the cooling rate, productivity, stability of curing of the thermoplastic resin by cooling, etc. are easily adjusted. Moreover, even if it cools after expansion, you may perform expansion and cooling substantially simultaneously.
[0038]
In the thermoformable core material, a surface material is laminated on the surface of the thermally active resin layer having the through hole, and is thermoformed to form an automobile ceiling material. The lamination and integration of the surface material may be performed simultaneously with the thermoforming of the thermoformable core material, or may be performed before the thermoforming. As said surface material, the nonwoven fabric which consists of natural fiber, a synthetic fiber, these mixed fiber etc. is used suitably, for example. Examples of natural fibers include cotton, wool, hemp and the like, and examples of synthetic fibers include polyester, polyamide, polyurethane and the like.
[0039]
By using non-woven fabric as the surface material, a part of the thermoactive resin on the surface of the thermoformable core material is impregnated inside the surface material. It will be.
[0040]
Examples of the method of laminating the surface material on the thermoformable core material include a method of stacking the surface material on the thermally active resin layer surface of the thermoformable core material and pressing in a heated state. Further, an adhesive thermoplastic resin layer may be formed between the thermoactive resin layer and the surface material.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
[0042]
(Example 1)
A glass fiber having a length of 40 to 75 mm and a diameter of 9 μm and a polypropylene fiber having a length of 64 mm, a thickness of 35 μm, and a melting temperature of 162 ° C. are mixed so that the weight ratio is 3: 2, and supplied to a card machine. , Mixed paper is matted, 20 locations / cm 2 With a needle punch, basis weight about 550g / cm 2 A mixed paper mat having a thickness of about 7.5 mm was obtained. A high-density polyethylene film having a thickness of 120 μm made of high-density polyethylene containing a small amount of maleic anhydride-modified polyethylene having a melting temperature of 135 ° C. and MFR7 was laminated on both sides of the obtained mixed paper mat to obtain a three-layer mat. .
[0043]
On the other hand, 6-nylon having a melting temperature of 230 ° C. and maleic acid-modified linear low-density polyethylene having a melting temperature of 125 ° C. and MFR10 were coextruded to obtain two two-layer films. In each of the two bilayer films, the thickness of the 6-nylon layer was 20 μm, and the thickness of the maleic acid-modified linear low-density polyethylene layer was 60 μm. One of the obtained two-layer films has an opening area of 28 mm. 2 Through holes having an opening shape of a circle having a diameter of 6 mm were punched at intervals of 10 mm.
[0044]
Next, the two-layer film in which the through-holes are formed on one surface of the three-layer mat, the other two-layer film on the other surface, and the 6-nylon layer side are in contact with the three-layer mat, Basis weight about 850g / m 2 A 7-layer mat having a thickness of about 8 mm was obtained.
[0045]
The obtained 7-layer mat was sandwiched between Teflon-coated glass cloth sheets, supplied to a hot air heating furnace at about 200 ° C., and left for 5 minutes. Thereafter, the 7-layer mat is sandwiched between glass cloth sheets, transferred to a flat plate press, compressed to a thickness of 1 mm, held in a compressed state for 5 seconds, then removed from the flat plate press, and from both sides of the glass cloth sheet side. It vacuum-sucked, it pulled at 0.5 mm / sec in the thickness direction, and it expanded until it became thickness 5.5mm. After air-cooling for 3 minutes in this expanded state, the glass cloth sheet was removed to obtain a thermoformable core material. The obtained thermoformable core material has a thickness of about 5.0 mm and a basis weight of about 850 g / m. 2 The total opening area of the through-holes was about 28% with respect to the area of the entire surface of the mat-like substrate, and most of the high-density polyethylene film of the 7-layer mat was impregnated in the mixed mat. The 6-nylon layer was not impregnated.
[0046]
FIG. 1 is a schematic cross-sectional view showing the obtained thermoformable core material. The thermoformable core material 1 is formed on the surface of a mat-
[0047]
(Example 2)
A high-density polyethylene containing a small amount of maleic anhydride-modified polyethylene having a melting temperature of 135 ° C and MFR7, 6-nylon having a melting temperature of 230 ° C, and a copolyamide having a melting temperature of 80 to 115 ° C are coextruded in this order, Two three-layer films were obtained. In each of the two three-layer films, the thickness of the high-density polyethylene layer was 120 μm, the thickness of the 6-nylon layer was 20 μm, and the thickness of the copolymerized polyamide layer was 60 μm. One of the obtained three-layer films has an opening area of 28 mm. 2 Through holes having an opening shape of a circle having a diameter of 6 mm were punched at intervals of 10 mm.
[0048]
Next, a three-layer film in which the above-mentioned through-holes are formed on one surface of the same mixed mat as in Example 1, another three-layer film on the other surface, and the high-density polyethylene layer side in contact with the mixed mat. Laminated, basis weight about 850g / m 2 A 7-layer mat having a thickness of about 8 mm was obtained. A thermoformable core material was obtained from the obtained 7-layer mat in the same manner as in Example 1. The obtained thermoformable core material has a thickness of about 5.0 mm and a basis weight of about 850 g / m. 2 Thus, the total opening area of the through holes was about 28% with respect to the area of the entire surface of the mat-like base material, and most of the high-density polyethylene layer of the 7-layer mat was impregnated in the mixed mat. The 6-nylon layer was not impregnated.
[0049]
(Comparative Example 1)
A high-density polyethylene film having a thickness of 100 μm made of high-density polyethylene containing a small amount of maleic anhydride-modified polyethylene having a melting temperature of 135 ° C. and MFR7 is laminated on both sides of the same mixed mat as in Example 1, and a three-layer mat. Got.
[0050]
On the other hand, a high-density polyethylene containing a small amount of maleic anhydride-modified polyethylene having a melting temperature of 135 ° C. and MFR2 and a maleic acid-modified linear low-density polyethylene having a melting temperature of 125 ° C. and MFR10 were coextruded. A layer film was obtained. In each of the two bilayer films, the thickness of the high-density polyethylene layer was 130 μm, and the thickness of the maleic acid-modified linear low-density polyethylene layer was 60 μm.
[0051]
Next, the two-layer film is laminated on both surfaces of the three-layer mat so that the high-density polyethylene layer side is in contact with the three-layer mat, and the basis weight is about 920 g / m. 2 A 7-layer mat having a thickness of about 8.3 mm was obtained. A thermoformable core material was obtained from the obtained 7-layer mat in the same manner as in Example 1. The obtained thermoformable core material has a thickness of about 5.0 mm and a basis weight of about 920 g / m. 2 The high-density polyethylene film of the seven-layer mat is mostly impregnated in the mixed mat, and a high-density polyethylene layer and a maleic acid-modified linear low-density polyethylene layer are also impregnated in part. It was.
[0052]
Creating automotive ceiling materials
Of the thermoformable core materials obtained in the examples and comparative examples, the basis weights of about 200 g /% made of polyester fibers were formed on the side where the through holes were formed for Examples 1 and 2 and on one side for Comparative Example 1. m 2 The non-woven fabric was placed and temporarily fixed at eight peripheral edges with staples. Next, heat the non-woven fabric so that the surface temperature of the non-woven fabric is about 190 ° C. and the surface temperature of the opposite side is about 180 ° C. In addition, the thermoformable core material and the nonwoven fabric were laminated and integrated, held in this state for 20 seconds, and then taken out from the press machine to obtain an automotive ceiling material.
[0053]
Evaluation of Adhesive Strength between Surface Material and Thermoformable Core Material A rectangular sample is cut out from the flat part of the obtained automotive ceiling material, and the non-woven fabric is peeled 90 ° from the thermoformable core material. The results are shown in Table 1.
○: The adhesive strength between the thermoformable core material and the nonwoven fabric was strong, and the nonwoven fabric was destroyed.
X: Peeled between the thermoformable core material and the nonwoven fabric.
[0054]
Evaluation of sound absorption of automotive ceiling materials
The sound absorption characteristics from the nonwoven fabric side of the obtained automotive ceiling material were measured according to JIS A 1405, and the sound absorption rates at 2.5 kHz, 4 kHz, and 6.3 kHz are shown in Table 1.
[0055]
Evaluation of non-breathability of automotive ceiling materials
Air permeability of flat part of the obtained ceiling material for automobile (cm Three / Cm 2 Second) was measured with a densometer, and the value is shown in Table 1.
[0056]
[Table 1]
【The invention's effect】
The thermoformable core material of the present invention is lightweight, excellent in rigidity, heat resistance, and heat formability, and has a heat resistant rigid resin layer that does not melt in the manufacturing process and thermoforming process on the back surface. Excellent breathability. Furthermore, since the sound from the surface side reaches the mat-like base material which is a porous body through the through hole of the thermoformable core material, the sound can be effectively attenuated and has excellent sound absorption. Yes. In addition, since a heat-resistant rigid resin layer that does not melt in the manufacturing process and thermoforming process is formed on the surface, the mat-like base material is not impregnated with the thermally active resin layer for bonding the surface material. The adhesive strength with the surface material is not impaired. Since the thermoformable core material of the present invention has the configuration as described above, it can be suitably used particularly as an automotive ceiling material.
[Brief description of the drawings]
1 is a schematic cross-sectional view of a thermoformable core material of the present invention obtained in Example 1. FIG.
[Explanation of symbols]
1 Thermoformable core material
2 Matt base material
3 Through hole
4, 6 6-nylon layer
5, 7 Maleic acid-modified linear low-density polyethylene layer
Claims (2)
Priority Applications (1)
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|---|---|---|---|
| JP2000230887A JP3654821B2 (en) | 2000-07-31 | 2000-07-31 | Thermoformable core material and manufacturing method thereof |
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| JP2000230887A JP3654821B2 (en) | 2000-07-31 | 2000-07-31 | Thermoformable core material and manufacturing method thereof |
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| Publication Number | Publication Date |
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| JP2002036405A JP2002036405A (en) | 2002-02-05 |
| JP3654821B2 true JP3654821B2 (en) | 2005-06-02 |
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| JP4001588B2 (en) * | 2004-04-09 | 2007-10-31 | 株式会社林技術研究所 | Molded interior materials for automobiles |
| JP4660318B2 (en) * | 2005-08-22 | 2011-03-30 | 三和工業株式会社 | Interior material for vehicle and method for manufacturing the same |
| JP5179786B2 (en) * | 2007-06-19 | 2013-04-10 | 株式会社林技術研究所 | Fender liner and manufacturing method thereof |
| JP6029279B2 (en) * | 2008-04-14 | 2016-11-24 | スリーエム イノベイティブ プロパティズ カンパニー | Multi-layer sound absorbing sheet |
| JP5743257B2 (en) * | 2010-11-18 | 2015-07-01 | 積水テクノ成型株式会社 | Thermoplastic resin foam molding and method for producing the same |
| WO2020261352A1 (en) * | 2019-06-25 | 2020-12-30 | 河西工業株式会社 | Interior component for automobile |
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