JP4047089B2 - Sandwich structure - Google Patents

Description

【００２８】
上式において、Ｐは曲げ荷重、ｌはスパン間距離、Ｅ_fは表面材の引張弾性率、ｔ_fは表面材の厚み、ｂは芯材の幅、Ｇ_cは芯材の剪断弾性率、ｔｃは芯材の厚みである。この式の右辺第２項から明らかなように、サンドイッチ構造部材の曲げたわみは、芯材の剪断弾性率に大きく依存している。ここで芯材の剪断弾性率が１ＭＰａよりも小さいと、高温環境下で走行すると、輸送機器走行時、車体が受ける風などによって変形し車体抵抗が増すため、燃費が悪くなる問題がある。さらに車体が受ける空気抵抗により、車体本体の振動が増えるため走行安定性が悪くなり、車内での居住性を得ることが出来ない。剪断弾性率は、高い値を示すものほどサンドイッチ構造部材の全体剛性が高くなり、軽量化が促進でき好ましい。１０〜１６０ＭＰａであると、サンドイッチ構造部材の曲げ応力により発生するたわみへの、芯材の寄与が十分小さくなり、芯材部分での破壊が極端に少なくなるのでさらに好ましい。
【００２９】
ウレタン発泡体芯材ａの１００℃での剪断強度は０．０１ＭＰａ以上１０ＭＰａ以下であると好ましい。０．０１ＭＰａより小さいと、高温環境下でサンドイッチ構造部材に人が寄りかかったりした時、芯材部分に非常に大きい剪断変形が生じ、芯材の層間剪断破壊や、芯材の荷重方向に対して４５°の方向にクラックが入る破壊など芯材内部で破壊が発生し好ましくない。このような破壊はサンドイッチ構造部材の内部での破壊であり目に見えないため、破壊している場所を特定できず、修理できないという問題がある。このような剪断強度の小さい発泡体を芯材として使うとき、サンドイッチ構造部材のたわみを出来るだけ小さくするため、密度の高い表面材の板厚を増す方法があるが、これでは部材の重量が極度に増えてしまうので好ましくない。１００℃での剪断強度は、高い値を示すものほどサンドイッチ構造部材の軽量設計が可能になり好ましい。
【００３０】
ウレタン発泡体芯材ａの密度（発泡体の密度は、ＪＩＳ Ｋ ７２２２により測定する）は０．０１ｇ／ｃｍ³以上０．３ｇ／ｃｍ³以下であると好ましい。０．０１ｇ／ｃｍ³より小さいと、ウレタン発泡体を構成する気泡（セルと呼ぶ）壁の厚みが極端に薄くなり、剛性不足となるので好ましくない。０．３ｇ／ｃｍ³より大きいと、従来技術である航空機や船舶のサンドイッチ構造体用芯材、すなわちアルミニウム製やノメックスペーパー製のハニカム材や、バルサなどの軽量木材に対し、軽量化効果を得ることができないので好ましくない。より好ましくは、０．０２５〜０．２４ｇ／ｃｍ³である。本発明では、前述の「発明が解決しようとする課題」である、「ウレタン発泡体が高剛性なサンドイッチ構造部材のさらなる軽量化を促進させることが出来る」ようにするため、とくに、上記０．０２５〜０．２４ｇ／ｃｍ ³ の密度範囲を採用している。
【００３１】
ウレタン発泡体芯材ａの独立気泡率は７５％以上であると好ましいが、本発明では、後述の実施例で現実に良好な結果が得られた、独立気泡率９３％以上に規定している。サンドイッチ構造部材は他の部品と接合するため穴加工し、芯材であるウレタン発泡体部分が外部環境に暴露されることがあり、独立気泡率が小さいと、湿度が高い環境や、雨の降る環境にさらされた時、芯材の連続気泡部分に水分が取り込まれ、ウレタン発泡体芯材ａが軟化し、結果サンドイッチ構造部材の表面にうねりがでてきてしまうため好ましくない。さらには、サンドイッチ構造部材は芯材が表面材により包まれているため、吸収された水分はほとんど揮発せず、サンドイッチ構造部材の重量が経時的に増加することになり好ましくない。
【００３２】
また、独立気泡率が小さいと、接着層となる樹脂が発泡体の内部に含浸することで、表面材／芯材間に接着層がなくなってしまい、接着強度が非常に弱くなる場合がある。また、このように樹脂や接着剤が発泡体の中に含浸すると、サンドイッチ構造部材の表面に存在する樹脂が少なくなってしまい、表面平滑性がなく、ざらざらな表面形態となってしまい好ましくない。
【００３３】
以下、上記ウレタン発泡体芯材に用いるウレタン発泡体に関し、さらに具体的に説明する。
ウレタン発泡体は、有機ポリイソシアネート、ポリオール、水及び／または発泡剤、触媒、整泡剤およびその他の助剤類からなるウレタン発泡体であって、寸法安定性が極めて優れ、表面品質が良好であり、サンドイッチ構造部材の芯材として、好適なウレタン発泡体である。以下、まずこれら製造に用いられる各成分およびウレタン発泡体の製造方法について詳細に説明する。
【００３４】
（有機ポリイソシアネート）
本発明に用いられるイソシアネート化合物としては、ポリウレタンの製造に用いるものであれば用いることができる。これらのイソシアネートは、単独でも複数を併用してもよく、それらのヌレート変性、プレポリマー変性、ウレトジオン変性等の変性をした変性体を用いてもよく、複数のポリイソシアネートや変性体をそれぞれ併用してもよい。
【００３５】
脂肪族ポリイソシアネート化合物としては、１、６−ジイソシアナトヘキサン（ＨＤＩ）等を挙げることができる。
【００３６】
脂環族ポリイソシアネート化合物としては、２、５−または２、６−ビスイソシアナトメチル−ビシクロ[２、２、１]ヘプタン（ＮＢＤＩ）、３、３、５−トリメチル−１−イソシアナト−５−イソシアナトメチルシクロヘキサン（ＩＰＤＩ）、１、６−ビスイソシアナトメチルシクロヘキサン（Ｈ₆−ＸＤＩ）、１、６−ジイソシアナトヘキサン（ＨＤＩ）、ビス（４、４’イソシアナトシクロヘキシル）メタン（Ｈ₁₂−ＭＤＩ）を挙げることができる。
【００３７】
芳香族に少なくとも２ヶ以上のイソシアネート基が直接結合する化合物としては、具体的に、４，４’−ジフェニルメタンジイソシアナート（４，４’−ＭＤＩ）、２，４’−ジフェニルメタンジイソシアナート（２，４’−ＭＤＩ）、２，４−トルエンジイソシアナート（２，４−ＴＤＩ）、２，６−トルエンジイソシアナート（２，６−ＴＤＩ）およびこれらの２量体、３量体または多量体、あるいはそれらの混合物である粗製ＴＤＩ、粗製ＭＤＩと称されるもの、並びにこれらの混合物が挙げられる。
【００３８】
芳香族基に直接結合しない少なくとも２個のＮＣＯ基を有するイソシアネート化合物としては、１、６−ビスイソシアナトメチルベンゼン（ＸＤＩ）等をあげることができる。
【００３９】
本発明においては、有機ポリイソシアネートとして、ジフェニルメタンジイソシアネート誘導体が好適に使用できる。ジフェニルメタンジイソシアネート誘導体は、分子骨格中に芳香環を有し、分子中の芳香環濃度が高く、耐熱性良好である。さらに、ウレタン発泡体としても高温時の物性低下を抑制できるので好適であ。しかも、常温で液状であるジフェニルメタンジイソシアネート誘導体化合物及びそれらの混合物が、取扱い上容易であり、更に好適である。
【００４０】
発泡体を製造する場合の有機ポリイソシアナートの使用量は、通常のウレタン発泡体の場合とほぼ同様であり、ＮＣＯ／ＯＨ（モル比）は、好ましくは０．７〜５．０、更に好ましくは１．０〜３．０、特に好ましくは１．０〜１．４である。
【００４１】
（ポリオール）
本発明におけるポリオール化合物としては、ポリエーテルポリオール、ポリエステルポリオール、ポリマーポリオール等のウレタン発泡体の製造に使用される公知のものを挙げることができるが、特にポリエーテルポリオールが好ましい。ポリエーテルポリオールとは分子内に２個以上の水酸基を持つ化合物にアルキレンオキシドを付加したものであり、ソルビトール／水／トリレンジアミン／トリエタノールアミン混合物にプロピレンオキシドを付加した水酸基価３５０ｍｇＫＯＨ／ｇのポリオールが好適である。それ以外に例えば、エチレングリコール、ジエチレングリコール、１，４−ブタンジオール、１，６−ヘキサングリコール、グリセリン、トリエチレングリコール、プロピレングリコール、ジプロピレングリコール、トリプロピレングリコール、トリメチロールプロパン、ペンタエリスリトール、ソルビトール、ショ糖等の多価アルコール、トリレンジアミン等の芳香族アミン類やエチレンジアミン、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン等の脂肪族アミン類の単独または混合系にアルキレンオキシドを付加重合させて得たヒドロキシル価２００〜５００ｍｇＫＯＨ／ｇのポリエーテルポリオール等がある。ここでアルキレンオキシドとしては、エチレンオキシド、プロピレンオキシド、ブチレンオキシド、スチレンオキシド等が挙げられる。
【００４２】
また、ポリエステルポリオールとしては公知のものがすべて使用できるが、脂肪族系多塩基酸、芳香族系多塩基酸及びその無水物と多価アルコ−ル類から生成するヒドロキシル価２００−５００ｍｇＫＯＨ／ｇのポリエステルジオール、ポリエステルトリオール等がある。脂肪族系多塩基酸及びその無水物としては例えばシュウ酸、マロン酸、アジピン酸、コハク酸、無水コハク酸などが挙げられる。また芳香族系多塩基酸及びその無水物としては例えばテレフタル酸、イソフタル酸、無水フタル酸、無水トリメリット酸、無水ピロメリット酸などが挙げられる。多価アルコ−ルとしては２〜８官能のもので、例えばエチレングリコ−ル、プロピレングリコ−ル、ブタンジオ−ル、プロパンジオ−ル、ジエチレングリコ−ル、トリメチルペンタンジオ−ル、グリセリン、ペンタンジオ−ル、ソルビト−ル、シュ−クロ−ス及び、これら多価アルコ−ル類のアルキレンオキシド付加物が使用可能である。また、これらのポリエステルポリオールにアルキレンオキシドを付加重合させて得た化合物も使用できる。さらに、ポリアルキレンテレフタレ−ト又はその釜残査をポリオ−ル中で加熱分解して得た生成物やポリカプロラクトンコポリエステルポリオ−ルも使用できる。
【００４３】
ポリマーポリオールとはポリアクリロニトリル、ポリスチレン、ポリウレア等を前述のポリエーテルポリオールに分散させたものである。これらのポリエーテルポリオール、ポリエステルポリオール、ポリマーポリオールは併用してもよい。これらは、単独または、混合ポリオールの官能基数は、２以上８以下が好ましく、３以上６以下であることが更に好ましく、４以上５以下であることが特に好ましい。
【００４４】
本発明では、成形時の表面品質が良好なポリエーテルポリオール類が好適に使用できる。それらのヒドロキシル価は、２００〜５００ｍｇＫＯＨ／ｇが好適であり、更に好ましくは、３００〜４００ｍｇＫＯＨ／ｇであり、官能基数は、得られた発泡体の機械強度から４以上５以下であることが特に好ましい。
【００４５】
（発泡剤）
本発明における発泡剤としては、ウレタンの発泡体の製造に供することができるものであれば、水、二酸化炭素ガス、炭化水素類、ハイドロクロロフルオロカーボン類（ＨＣＦＣ類）、ハイドロフルオロカーボン類（ＨＦＣ類）、ハイドロフルオロエーテル類（ＨＦＥ類）が挙げられる。これら発泡剤は、単独で使用してもよいが、複数を併用して用いてもよい。例えば水と二酸化炭素、水とメタン、エタン、プロパン、ペンタン、イソペンタン、シクロペンタン等低沸点炭化水素類、水とハロゲン化炭化水素等を併用することができる。
【００４６】
本発明では、水、二酸化炭素などの環境負荷の少ない発泡剤を使用することが特に好ましい。水は、ポリイソシアナートと反応して二酸化炭素を発生することにより発泡剤として使用され、通常、イオン交換水、蒸留水が用いられるが、場合により、工業用水をそのまま用いることもできる。水の量は、全ポリオール成分１００重量部当たり、０．５〜１０重量部用いることができ、更に好ましくは１．０〜９．５重量部である。
【００４７】
本発明においては、得られる発泡体において、高温時の機械物性の低下を抑制するため、尿素結合とウレタン結合の比率（尿素結合／ウレタン結合）が、０．１３３以上０．８０１以下であることが好ましく、これらの点からも発泡剤として使用する水の量は、全ポリオール成分１００重量部当たり、特に好ましくは１．５〜９．０重量部である。
【００４８】
（触媒）
触媒としては、通常ウレタン発泡に用いられる公知の触媒すべてを使用することができる。例えば、トリメチルアミノエチルピペラジン、トリエチルアミン、トリプロピルアミン、Ｎ−メチルモルフォリン、Ｎ−エチルモルフォリン、トリエチレンジアミン、テトラメチルヘキサメチレンジアミン、ジメチルシクロヘキシルアミン、ジアゾビシクロウンデセン、１，３，５−トリス（ジメチルアミノプロピル）ヘキサヒドロ−ｓ−トリアジン等のトリアジン類、２−エチルアジリジン等のアジリジン類等のアミン系化合物、３級アミンのカルボン酸塩等の４級アンモニウム化合物、アリルグリシジルエーテル、ポリアルキレングリコールジグリシジルエーテル、スチレンオキサイド等のアルカリ金属塩、ナフテン酸鉛、オクチル酸鉛等の鉛化合物、ジブチル錫ジアセテート、ジブチル錫ジラウレート等の錫化合物、ナトリウムメトキシド等のアルコラート化合物、カリウムフェノキシド等のフェノラート化合物、塩化鉄、塩化亜鉛、臭化亜鉛、塩化錫等の金属ハロゲン化物、アセチルアセトン金属塩等の金属錯化合物等を挙げることができる。これらの触媒は、単独または、２種以上併用して用いることができ、その使用量は、ポリオール１００重量部に対して、０．００１〜１５．０重量部が適当である。製造時のプロセスにも依存するが、製品品質獲得と生産性を考慮した場合、取扱い上比較的安全であり、発泡体製造後も発泡体中に金属分を含有しない、有機アミン類を０．１〜５重量部の範囲で使用することが特に好ましい。
【００４９】
（整泡剤）
整泡剤としては、従来公知の含珪素有機系の界面活性剤が用いられる。例えば、日本ユニカ−（株）製のＳＺ−１１２７、ＳＺ−１１４２、ＳＺ−１６０５、ＳＺ−１６４２、ＳＺ−１６４９、ＳＺ−１６５５、Ｌ−５８０、Ｌ−５７４０、Ｌ−５４２０、Ｌ−５４２１等、東レ・ダウコーニング・シリコーン（株）製のＳＦ−２９３５Ｆ、ＳＦ−２９３８Ｆ、ＳＦ−２９４０Ｆ、ＳＦ−２９４５Ｆ、ＳＦ−２９０８、ＳＲＸ−２９４Ａ、ＳＨ−１９０、ＳＨ−１９２、ＳＨ−１９３等、信越化学工業（株）製のＦ−３２７、Ｆ−３４５、Ｆ−３０５、Ｘ−２０−１３２８等が適当である。これらの整泡剤の使用量は、ポリオールと有機ポリイソシアネートの総和１００重量部に対して０．０１〜１０重量部である。経済性の点から、０．０１〜５重量部の範囲で使用するのが特に好ましい。
【００５０】
（その他ポリウレタン製造時の添加剤）
本発明においては、必要に応じて助触媒、難燃剤、可塑剤、安定剤、充填剤、着色剤等の助剤を添加することができる。助触媒としては、例えば、エチレンカーボネート、プロピレンカーボネート等のカーボネート化合物やリン酸エステル、亜リン酸エステル等のリン酸化合物等を挙げることができる。難燃剤としては、通常住宅・建材用断熱ポリウレタンフォーム製造時に用いられる、トリス（クロロプロピル）ホスフェート等を挙げることができる。
【００５１】
（ウレタン発泡体の製造方法）
本発明に係るウレタン発泡体の製造方法とは、以下のようにして製造する。有機ポリイソシアネートとポリオールは発泡直前で混合することが好ましい。その他の発泡剤、触媒及び整泡剤、適宜使用する助剤類は、必要に応じてポリイソシアネートまたはポリオールと予め混合することが一般的であり、それら混合物は混合後直ちに使用しても、貯留し必要量を適宜使用してもよい。その他の成分の混合は必要に応じて適宜その混合の組み合わせ、混合順序、混合後の貯留時間等を決定することができる。
【００５２】
このような混合物のうちポリオールとその他の成分の混合物、即ちポリオールと発泡剤、触媒、整泡剤等、必要に応じて使用するその他添加剤を混合したものをレジンプレミックスと呼称することがある。これらの組成は必要とされるウレタン発泡体の品質によって適宜設定することができる。このレジンプレミックスはポリイソシアネートと反応させる。
【００５３】
ポリイソシアネートは未変性のものでも変性したものでも又それらの混合物のいずれであってもよい。使用するレジンプレミックスの粘度は発泡機での混合性、ウレタン発泡体の成形性の観点から２，５００ｍＰａ・ｓ／２５℃以下が好ましい。
【００５４】
混合方法は、有機ポリイソシアネートとレジンプレミックスを混合する上で、均一に混合可能であれば、いかなる装置でも使用することができる。例えば、衝突混合、撹拌混合いずれでの混合方法を用いてもよい。衝突混合装置としては、一般のウレタン発泡体製造用の高圧発泡機を使用することができる。また、撹拌混合装置としては、例えば、小型ミキサーや一般のウレタン発泡体製造用の低圧発泡機を使用することができる。混合温度、圧力は目的のウレタン発泡体の品質、原料の種類や組成によって必要に応じて任意に設定することができ、混合に先立ち必要に応じて加熱することもできる。
【００５５】
イソシアネート基と活性水素基の割合（ＮＣＯ／ＯＨ当量比）は、０．７〜５．０の範囲、好ましくは１．０〜３．０の範囲であり、１．０〜１．４の範囲が特に好適である。ＮＣＯ／ＯＨ当量比を０．５以下とすることで、よりすぐれた表面品質を発現できるので好ましい。
【００５６】
また、得られる発泡体において、高温時の機械物性の低下を抑制するため、尿素結合とウレタン結合の比率（尿素結合／ウレタン結合）が、０．１３３以上０．８０１以下に配合設計することが特に好ましい。尿素結合とウレタン結合の比率（尿素結合／ウレタン結合）が０．１３３以上では、樹脂軟化点（動的粘弾性測定におけるＴａｎδ値）が１５０℃以上となり、高温時の物性をより高く保つことができるので好ましい。また、０．８０１以下とすることで発泡体の表面品質をよりすぐれたものにすることができる。
【００５７】
発泡方法としては、スラブ、モールド発泡、注入発泡、スプレー発泡、ラミネート発泡など、公知のあらゆる成形技術を用いても差し支えない。発泡時、有機ポリイソシアネート及びレジンプレミックスを液温１５〜８０℃、好ましくは２０〜５０℃で混合し、常圧或いは場合により減圧または、高圧下で、必要に応じて温度制御の可能な金型に導入する事により好適なウレタン発泡体を得ることができる。
【００５８】
本発明のウレタン発泡体を芯材とするサンドイッチ構造部材は、自動車、高速車両、高速船艇、単車、自転車、航空機など輸送機器のサンドイッチ構造部材用芯材として、また冷蔵庫、温調機、スピーカーなどの電化製品や、風車、低温倉庫、冷蔵倉庫、低温試験室畜舎、サイロ、ビル、住宅、工場など建築材料のサンドイッチ断熱構造部材用芯材として好適に利用することができる。具体的には、輸送機器のサンドイッチ構造部材としては、ドア、ボンネット、フェンダー、トランクリッド、ハードトップ、サイドミラーカバー、プラットホーム等の自動車部材、また先頭車両ノーズ、ルーフ、サイドパネル、ドア等の車輌用部材、ウイングトラックにおけるウイングのイナーパネル、アウターパネル、ルーフ、フロアー等、自動車や単車に装着するエアースポイラーやサイドスカートなどのエアロパーツ等、またフレーム、ハンドル、変速レバー、ブレーキバー、フロントハブ、クランク、フリーハブ、ディレイラー、シートピラー、サドル等の自転車である。また、電化製品としては、冷蔵庫、温調機などの断熱、防音部材や、建築材料としては、住宅用断熱ボード、外壁材、内装材、タンク、配管などの断熱部材としても好適に使用できる。
【００５９】
以下、本発明を実施例に基づき具体的に説明する。なお、実施例、比較例において、各種サンプルの作成、物性値の測定は次に示すような条件で行った。
【００６０】
（ウレタン発泡体の作成）
（使用原料）
有機ポリイソシアナートＡ：コスモネートＭ−２００（三井武田ケミカル（株）社製の有機ポリイソシアナート。ＮＣＯ％＝３１．４％）。
ポリオールＸ：以下に記載のポリオールＡ、ポリオールＢ、ポリオールＣのそれぞれ２８：１２：６０重量比の混合ポリオール(三井武田ケミカル（株）社製のポリオール。水酸基価３５０ｍｇＫＯＨ／ｇ)
ポリオールＡ：ペンタエリスリトールに水酸化カリウムを触媒として反応温度１１０℃でプロピレンオキシドを付加して得られる水酸基価が３５０ｍｇＫＯＨ／ｇのポリオール。ポリオールＢ：トリレンジアミンとトリエタノールアミンの７０：３０重量比の混合物に、水酸化カリウムを触媒として反応温度１１０℃でプロピレンオキシドを付加して得られる水酸基価３５０ｍｇＫＯＨ／ｇのポリオール。
ポリオールＣ：ソルビトールと水の９７：３重量比の混合物に、水酸化カリウムを触媒として反応温度１１０℃でプロピレンオキシドを付加して得られる水酸基価３５０ｍｇＫＯＨ／ｇのポリオール。
触媒Ａ：カオライザーＮｏ．１０（花王（株）社製でＮ，Ｎ−ジメチルシクロヘキシルアミン）。
シリコーン整泡剤Ａ：Ｘ−２０−１３２８（信越化学工業（株）製のポリジメチルシロキサン誘導体）。
発泡剤Ａ：代替フロンＨＣＦＣ−１４１ｂ（ダイキン工業（株）社製で１，１−ジクロロ−１−フルオロエタン）
【００６１】
（発泡方法）
発泡は次のように行った。ポリオールＸ１００重量部に対し、シリコーン整泡剤Aを２重量部、目的密度のウレタン発泡体を得るための所定量の水および／または物理発泡剤（炭化水素類、ハロゲン化炭化水素類）、触媒Ａをゲルタイム８０±５秒とするための必要量混合した液に、有機ポリイソシアナートＡをＮＣＯ／ＯＨ当量比が１．１となるように加え、液温２５℃で高速回転ラボスターラーを用い６，０００ｒｐｍで約６秒間混合し、この混合物を幅３００ｍｍ、長さ３００ｍｍ、高さ３００ｍｍの蓋のない木製のボックス内に素早く注入し、室温下で硬化した後、注入後１５分で型から取り出し、ウレタン発泡体を作成した。
【００６２】
（ウレタン発泡体の密度の測定）
上記の方法で得たウレタン発泡体を翌日スリッターで幅９５ｍｍ、長さ９５ｍｍ、厚み９５ｍｍの試験片を切り出し、ＪＩＳ Ｋ ７２２２に準拠して、発泡体内部のフリー密度(見掛け密度)を測定した。
【００６３】
（ウレタン発泡体の独立気泡率の測定）
上記の方法で得たウレタン発泡体を翌日スリッターで幅２５ｍｍ、長さ２５ｍｍ、厚み３５ｍｍの試験片を切り出し、通常硬質ポリウレタンフォームの独立気泡率測定に用いられる方法に従った。具体的には「空気式見掛け容積測定器」を使用して、ＡＳＴＭ Ｄ−２８５６に記載の方法により測定される見掛け容積率（％）である。本発明に係る独立気泡率は、東芝ベックマン空気比重計モデル９３０を用いて測定した値である。
【００６４】
（ウレタン発泡体の剪断強度、弾性率の測定）
上記の方法で得たウレタン発泡体から、ＡＳＴＭＣ２７３に準拠して、幅５０ｍｍ、長さ１５０ｍｍ、厚み１０ｍｍの試験片を切り出し、剪断弾性率を測定した。高温環境下の測定にさいしては、１００℃のオーブン中で測定を行った。
【００６５】
（サンドイッチ構造部材の作成）
図２は、本発明の繊維強化複合材を製造中の複合材とその製造装置の平面図である。
まず、サンドイッチ構造部材の作成方法を説明する前にこれら図面の説明をすると、図２において、１は剛体片面型として用いるアルミニウム板である。２はブリーザー（通気材）として用いるガラス繊維織物、３、５は強化繊維基材である炭素繊維織物、４は芯材であるウレタン発泡体、６はピールプライ（剥離を容易にするための被覆材）として用いるポリエステルタフタ、７は樹脂拡散媒体であるプラスチック製メッシュである。９，１２はそれぞれ空気（樹脂含む）吸引用、マトリクス樹脂注入用のアルミニウム製チャンネルであり、図示しないマトリクス樹脂容器への接続路であるＡ路からはマトリクス樹脂を注入でき、一方真空ポンプへの接続路であるＢ路へは強化繊維２〜樹脂拡散媒体７部内から空気を吸引できるようになっている。なお、吸引路Ｂには吸引した樹脂を除去するため図示しないトラップが設けられている。また、１３は減圧時に外部から空気が内部に流入するのを防ぐためのシリコーンシーラント、８は可撓性フィルムとして用いるナイロン製フィルム、１０と１１はそれぞれ空気の吸引口とマトリクス樹脂の注入口となるポリエチレン製チューブである。
【００６６】
図２において、剛体の片面型と可撓性フィルムおよび樹脂拡散媒体を用いるＲＴＭ法（レジントランスファーモールディング法）により繊維強化複合材を作成した。具体的な製造手順を以下に示す。
【００６７】
図２のアルミニウム板１として500mm×500mmのものを用い、その成形する表面に離型剤（ダイキン工業社製ＧＡ−６０１０）をスプレーした。アルミニウム板１の一辺に、平行にガラス繊維織物２としてテープ状のものを置いた。炭素繊維織物３として長さ３５０ｍｍ幅３５０ｍｍに切り出した織物（東レ社製ＣＫ６２４３Ｃ、炭素繊維品種：Ｔ７００Ｓ、組織：平織、目付：３００ｇ／ｍ²）を用い、この３枚を一辺がガラス繊維織物２とわずかに重なるように置いた。ウレタン発泡体４として上記で作成した長さ３００ｍｍ、幅３００ｍｍ、高さ３００ｍｍのウレタン発泡体を高さ１０ｍｍとなるよう切り出し、その後、図３に示すようにウレタン発泡体４の片表面に深さ２ｍｍ、幅１ｍｍの溝を３０ｍｍピッチで加工し、溝Ｃを加工した面が見えないよう下向きに炭素繊維織物３の上に置いた。続いて、炭素繊維織物５として長さ３７０ｍｍ幅３７０ｍｍに切り出した織物（東レ社製ＣＫ６２４３Ｃ、炭素繊維品種：Ｔ７００Ｓ、組織：平織、目付：３００ｇ／ｍ²）を用い、この３枚を炭素繊維織物３を覆うようにウレタン発泡体４の上に置いた。炭素繊維織物５よりやや大きめに切り出したポリエステルタフタ６で炭素繊維織物を覆った。また、樹脂拡散媒体としてプラスチック製メッシュ７（三井石化産資社製ＴＳＸ−１６０）を炭素繊維織物５が、ガラス繊維織物２と重なっていない部分を覆うように置いた。そして、空気および樹脂の吸引路としてアルミニウム製チャンネル９をガラス繊維織物２上に置き、樹脂注入路としてもう一つのアルミニウム製チャンネル１２をプラスチック製メッシュ７のガラス繊維織物２と対向する辺付近に置いた。アルミニウム板１の周囲にシリコーンシーラント１３を置き、全体をナイロン製フィルム８で覆った。そして、ガラス繊維織物２上に置いたアルミニウムチャンネル９の端面を覆うナイロン製フィルム８に穿孔し、これにポリエチレン製チューブ１０を挿入してチューブ１０とフィルム９が接する部分をシリコーンシーラントで密封し、吸引口とした。さらにプラスチック製メッシュ５上に置いたアルミニウム製チャンネル１２側にも同様にポリエチレン製チューブ１１を挿入し、注入口とした。
【００６８】
そして、上記図２の全体をホットプレート上に設置し、樹脂注入口側のチューブ１１をエポキシ樹脂組成物の温水ジャケット付き容器に接続し、吸引口側のチューブ１０をガラス製トラップとバルブを介して真空ポンプに接続し、樹脂容器と装置全体を40℃に加温した。図示しない真空ポンプを作動させて吸引し、型内にエポキシ樹脂組成物を注入した。エポキシ樹脂組成物が型内を満たし、トラップに流出するエポキシ樹脂組成物に概ね気泡がみられなくなったことを目視で確認後、バルブを閉じ、注入口側と吸引口側のチューブを切断して、装置を40℃になっている熱風オーブン中に移した。オーブンを昇温速度1.5℃／minで９０℃まで昇温し、９０℃で３時間保持して硬化を行った。硬化終了後装置を解体して繊維強化複合材の板を取り出し、プラスチック製メッシュとポリエステルタフタを剥ぎ取った。
【００６９】
エポキシ樹脂組成物としては、セロキサイド2021P（ダイセル化学工業（株）製エポキシ樹脂）２５．０重量部、ERL-4299（ユニオンカーバイド日本（株）製エポキシ樹脂）７５．０重量部、ジエチレングリコール（和光純薬工業（株）製）９．６重量部、SEESORB 704（シプロ化成（株）製、紫外線吸収剤）０．１重量部、リカシッド MH-700（新日本理化（株）製酸無水物）９１．３重量部、キュアゾール1,2-DMZ（四国化成工業（株）製イミダゾール）５．７重量部を調合し、エポキシ樹脂組成物を得た。
【００７０】
得られたサンドイッチ構造部材は、表面にボイド等ないものであった。
（サンドイッチ構造部材の剪断強度の測定）
上記の方法で得たサンドイッチ構造部材から、ＡＳＴＭＣ２７３に準拠して、幅２５ｍｍ、長さ１５０ｍｍ、実際の成形品厚みのサイズに試験片を切り出し、１００℃および２３℃におけるラップシェアー試験を行い、サンドイッチ構造部材の剪断強度を測定した。ここでサンドイッチ構造部材を切り出す時、溝部分がサンプルに入らないよう、丁寧に切断した。その後、ここから得られる１００℃の剪断強度／２３℃の剪断強度の値を算出した。
【００７１】
【実施例】
（実施例１）
ポリオールＸ１００重量部に対し、触媒Ａを０．８重量部と、シリコーン整泡剤Ａを２重量部と、水を５重量部とを混合した液に、ＮＣＯ／ＯＨ当量比が１．１となるよう有機ポリイソシアナートＡを１７３．５重量部加え、液温２５℃で高速回転ラボスターラーを用い６，０００ｒｐｍで約６秒間混合し、この混合物を幅３００ｍｍ、長さ３００ｍｍ、高さ３００ｍｍの蓋のない木製のボックス内に素早く注入し、室温下で硬化した後、注入後１５分で型から取り出し、ウレタン発泡体を作成した。このときの（尿素結合／ウレタン結合）比率は０．４４５である。
【００７２】
成形したウレタン発泡体の密度、剪断強度、および剪断弾性率を前述の方法により測定したところ、密度は０．０７ｇ／ｃｍ³、独立気泡率は９３％、２３℃での剪断強度は０．１ＭＰａ、１００℃での剪断強度は０．０５ＭＰａであり、１００℃での剪断強度／２３℃での剪断強度の比が０．５であった。また、１００℃での芯材の剪断弾性率は５ＭＰａであった。
【００７３】
次に、このウレタン発泡体を芯材として前述の方法でサンドイッチ構造部材を成形し、前述の方法よりサンドイッチ構造部材の剪断強度を測定したところ、１００℃の剪断強度／２３℃の剪断強度の値は０．５５であった。
【００７４】
（参考例１）
ポリオールＸ１００重量部に対し、触媒Ａを０．８重量部と、シリコーン整泡剤Ａを２重量部と、水を１．５重量部とを混合した液に、ＮＣＯ／ＯＨ当量比が１．１となるよう有機ポリイソシアナートＡを１１６．３重量部加えた以外は実施例１と同様にして、ウレタン発泡体を作成した。このときの（尿素結合／ウレタン結合）比率は０．１３４である。
【００７５】
成形したウレタン発泡体の密度、剪断強度、および剪断弾性率を前述の方法により測定したところ、密度は０．２６ｇ／ｃｍ³、独立気泡率は９４％、２３℃での剪断強度は１３．５ＭＰａ、１００℃での剪断強度は９．５ＭＰａであり、１００℃での剪断強度／２３℃での剪断強度の比が０．７であった。また、１００℃での芯材の剪断弾性率は１５０ＭＰａであった。
【００７６】
次に、このウレタン発泡体を芯材として前述の方法でサンドイッチ構造部材を成形し、前述の方法よりサンドイッチ構造部材の剪断強度を測定したところ、１００℃の剪断強度／２３℃の剪断強度の値は０．８であった。
【００７７】
（比較例１）
ポリオールＸ１００重量部に対し、触媒Ａを０．８重量部と、シリコーン整泡剤Ａを２重量部と、水を１．０重量部と、発泡剤Ａを２６．０重量部を混合した液に、ＮＣＯ／ＯＨ当量比が１．１となるよう有機ポリイソシアナートＡを１０８．１重量部加えた以外は実施例１と同様にして、ウレタン発泡体を作成した。このときの（尿素結合／ウレタン結合）比率は０．０８９である。
【００７８】
成形したウレタン発泡体の密度、剪断強度、および剪断弾性率を前述の方法により測定したところ、密度は０．０７ｇ／ｃｍ³、独立気泡率は８９％、２３℃での剪断強度は０．０８ＭＰａ、１００℃での剪断強度は０．００９ＭＰａであり、１００℃での剪断強度／２３℃での剪断強度の比が０．１であった。また、１００℃での芯材の剪断弾性率は０．９ＭＰａであった。
【００７９】
次に、このウレタン発泡体を芯材として前述の方法でサンドイッチ構造部材を成形し、前述の方法よりサンドイッチ構造部材の剪断強度を測定したところ、１００℃の剪断強度／２３℃の剪断強度の値は０．１であった。
【００８０】
（比較例２）
ポリオールＸ１００重量部に対し、触媒Ａを０．８重量部と、シリコーン整泡剤Ａを２重量部と、水を１．０重量部と、発泡剤Ａを３．２重量部とを混合した液に、ＮＣＯ／ＯＨ当量比が１．１となるよう有機ポリイソシアナートＡを１０８．１重量部加えた以外は実施例１と同様にして、ウレタン発泡体を作成した。このときの（尿素結合／ウレタン結合）比率は０．０８９である。
【００８１】
成形したウレタン発泡体の密度、剪断強度、および剪断弾性率を前述の方法により測定したところ、密度は０．２６ｇ／ｃｍ³、独立気泡率は９０％、２３℃での剪断強度は１１ＭＰａ、１００℃での剪断強度は３．３ＭＰａであり、１００℃での剪断強度／２３℃での剪断強度の比が０．３であった。また、１００℃での芯材の剪断弾性率は８５ＭＰａであった。
【００８２】
次に、このウレタン発泡体を芯材として前述の方法でサンドイッチ構造部材を成形し、前述の方法よりサンドイッチ構造部材の剪断強度を測定したところ、１００℃の剪断強度／２３℃の剪断強度の値は０．４５であった。
以上の結果は表１にまとめた。
【００８３】
【表１】

【００８４】
表１に示すように、実施例１、参考例１のものは、（尿素結合／ウレタン結合）比率が０．４４５および０．１３４であり、このようなウレタン発泡体をサンドイッチ構造部材の芯材とすることで、１００℃での剪断強度／２３℃での剪断強度の比が０．５５および０．８となり、低下率を小さくすることができた。また、この時、ウレタン発泡体芯材の１００℃での剪断強度／２３℃での剪断強度の比は０．５および０．７であった。とくに、実施例１のものは、表１に示すように、成形芯材の密度が０．０７ｇ／ｃｍ ³ であり、参考例１（成形芯材の密度：０．２６ｇ／ｃｍ ³ ）に比べ、さらなる軽量化を促進させることが出来る。
【００８５】
一方、比較例１、２においては、（尿素結合／ウレタン結合）比率がどちらも０．０８９であり、このようなウレタン発泡体をサンドイッチ構造部材の芯材とすること、１００℃での剪断強度／２３℃での剪断強度の比が０．１および０．４５となり、低下率の大きいものであった。また、この時、ウレタン発泡体芯材の１００℃での剪断強度／２３℃での剪断強度の比は０．１および０．３であった。
【００８６】
【発明の効果】
以上説明したように、本発明のサンドイッチ構造部材によれば、軽量であり、高温環境下での剪断強度および剪断弾性率を高めることができる。また、本発明に使用するウレタン発泡体はサンドイッチ構造部材のさらなる軽量化を促進させることが出来るばかりでなく、高温環境下で局所的な集中荷重にも耐えるので、自動車、車輌、航空機などの輸送機器用構造部材として好適に適用できるものである。
【図面の簡単な説明】
【図１】本発明のサンドイッチ構造部材の概略部分断面図である。
【図２】本発明のサンドイッチ構造部材を製造中の複合材とその製造装置の一部破断部を示す平面図である。
【図３】本発明のサンドイッチ構造部材の製造に使用する芯材の一例を示す透視斜視図である。
【符号の説明】
ａ 芯材
ｂ 表面材
１ アルミニウム板
２ ガラス繊維織物
３ 炭素繊維織物
４ ウレタン発泡体
５ 炭素繊維織物
６ ポリエステルタフタ
７ プラスチック製メッシュ
８ ナイロン製フィルム
９ アルミニウム製チャンネル
１０ ポリエチレン製チューブ
１１ ポリエチレン製チューブ
１２ アルミニウム製チャンネル
１３ シリコーンシーラント
Ａ 樹脂容器への接続路
Ｂ 真空ポンプへの接続路
Ｃ 溝[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sandwich structure member using a urethane foam having excellent heat resistance and high shear strength and high shear modulus even in a high temperature environment.
[0002]
[Prior art]
Urethane foam is a material with very good heat insulation, and is often used in refrigerators and housing panels, but recently it has also been used as a core material for fiber-reinforced composite materials (hereinafter referred to as FRP). I'm starting. In particular, a sandwich structure composed of a high-rigidity surface material such as FRP and a low-density core material can make lightweight and high-rigidity structural members, which is a major factor in the transportation equipment industry such as automobiles, vehicles, and aircraft. Has attracted attention.
[0003]
For example, Japanese Patent Laid-Open No. 11-78874 discloses a bulk density of 0.02 to 0.2 (20 kg / m when converted to the same unit density as the above publication as a core material of an outer wall of a sandwich structure for a high-speed railway vehicle.^ThreeTo 200kg / m^ThreeA technique using a hard foamed synthetic resin within the range of In this publication, the strength of the outer wall of a high-speed railway vehicle is improved and the weight is reduced by adjusting the bulk density of a rigid foam synthetic resin made of polymethacrylimide or the like within a range of 0.02 to 0.2. Is described as being possible. However, if the strength and rigidity of the foam are increased by increasing the density of the foam, the weight of the sandwich structure member increases, which is a problem.
[0004]
In JP 2000-167965 A, a foam having a small thermal deformation rate anisotropy in a high temperature environment is used as a core material to form a sandwich structure member, which is excellent in dimensional stability even in a high temperature environment. It is described that it is possible to provide a sandwich structure member that does not break due to thermal stress due to thermal stress generated inside the sandwich structure member, that is, does not lower the overall strength.
[0005]
However, when the sandwich structure member is not subject to thermal stress as described above, the core material is sheared when subjected to a local bending load, such as a person leaning on it, being supported by a pillar, or hitting an object. There is a problem in that the high rigidity characteristic of the sandwich structure member cannot be maintained due to fracture in the direction (specifically, the crack progresses in a direction of about 45 ° with respect to the thickness direction of the sandwich structure member). there were. In order to reduce the destruction of the core material due to such local bending load, it is necessary to increase the shear strength of the core material, and conventionally the shear strength of the core material has been increased by increasing the density of the core material. However, the weight of the sandwich structure member is also increased here, and the merit of using the sandwich structure has been reduced.
[0006]
In addition to the room temperature, the absolute values of the shear strength and the shear elastic modulus at the part where the temperature is high, especially at the high temperature of use, are very important in design. That is, depending on the area (Okinawa etc.) to be used, the surface temperature of the transport equipment reaches a temperature close to 100 ° C. during the day, and the overall bending strength decreases as the shear strength of the core of the sandwich structure member decreases. For this reason, the shear failure in the core material due to the local bending load is likely to proceed, which is a problem. In this case as well, the shear strength can be increased by increasing the density of the core material, but there is a problem that the weight of the entire member becomes heavy. On the other hand, in the past, by using a plastic deformable metal that absorbs a lot of energy as the surface material, the shear fracture of the core material has been reduced, but the density of the metal is the density of the fiber reinforced composite material. Therefore, the weight reduction of the sandwich structure member cannot be promoted.
[0007]
In addition, since the overall rigidity decreases with a decrease in the elastic modulus of the core material of the sandwich structural member in a high temperature environment, depending on the magnitude of the decrease rate, the structure member cannot be realized. Furthermore, when traveling in a high temperature environment, the vehicle body of the transport equipment is subtly deformed by the wind received during traveling and the vehicle body resistance is increased, so there is a problem that the fuel stability is deteriorated and the driving stability is deteriorated because vibration is increased. Absent. In order to increase the overall rigidity of the sandwich structure member, this can be dealt with by increasing the density of the core material, but as described above, the weight of the entire member becomes heavy. In addition, there is a method of increasing the shear modulus of the core material by increasing the thickness of the core material in the sandwich structure member, or increasing the rigidity of the surface material by increasing the thickness of the surface material. Not only has the weight increased, but there has also been a problem of assembly parts accompanying the increase in the thickness of the entire member, and the possibility of practical use has become extremely low.
[0008]
That is, in order to design a sandwich structure member without impairing the lightness, it is an urgent need to develop a core material for a sandwich structure material having a low density and a high shear strength and high shear modulus under a high temperature environment. To reiterate, when the density of the foam is increased and the shear strength and shear modulus are increased, the problem of an increase in the weight of the entire sandwich structure member arises.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the prior art, that is, a sandwich structure using a urethane foam that is lightweight and has a high shear strength and high shear modulus under a high temperature environment as a core material. It is to provide. Such urethane foams can not only promote further weight reduction of high-rigidity sandwich structure members, but also withstand localized concentrated loads in high-temperature environments, and can be used for transportation equipment such as automobiles, vehicles, and aircraft. It can be suitably applied as a structural member.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention has the following configuration.
(1) A core material made of urethane foam having a thickness of 20 mm or less as a core material, and a surface material of the core material, the thickness of at least a part or all being 0.02 mm or more and 4 mm or less. The ratio (A / B) of the shear strength (A) at 100 ° C. and the shear strength (B) at 23 ° C. is in the range of 0.5 or more and 0.95 or less. The urethane foam has a closed cell ratio of 93% or more and a density of0.025 g / cm ^Three 0.24 g / cm ^Three Less thanA sandwich structure member characterized by the above.
[0011]
(2) The urethane foam is a urethane foam formed by combining at least one selected from organic polyisocyanate, polyol, water and / or a foaming agent, a catalyst, a foam stabilizer, and an auxiliary agent. The sandwich structure member according to (1), wherein the ratio of the bond to the urethane bond (urea bond / urethane bond) is in the range of 0.133 to 0.801.
[0012]
(3) The sandwich structure member according to (1) or (2), wherein carbon fiber is contained in at least a part or all of the surface material.
[0013]
(4) The sandwich structure member according to any one of (1) to (3), wherein the urethane foam has a shear elastic modulus at 100 ° C. in a range of 1 MPa to 200 MPa.
[0014]
(5) The sandwich structure member according to any one of (1) to (4), wherein the urethane foam has a shear strength at 100 ° C. in a range of 0.01 MPa to 10 MPa.
[0017]
(6(1) to (1) characterized by being used as a member for automobiles5) A sandwich structure member according to any one of the above.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a sandwich structure member according to the present invention will be described in detail together with embodiments.
As shown in FIG. 1, the sandwich structure member of the present invention has a laminated structure of a urethane foam core material a and a surface material b.
[0019]
The urethane foam core material a of the sandwich structure member of the present invention has a thickness of 20 mm or less at least partially or entirely. If the thickness exceeds 20 mm, the second moment of the cross-section of the sandwich structure member becomes high and the rigidity becomes high. On the other hand, the thickness of the member becomes thick, which is not preferable due to inconvenience in terms of component connection. In addition, in the case of electrical system parts that release heat or members around power system parts, the gap between the electrical system parts or power system parts and the sandwich structure members should be increased in order to reduce heat transfer to the sandwich structure members as much as possible. When the thickness of the sandwich structure member is increased, the distance between the sandwich structure members is decreased, and the sandwich structure member must be further heat resistant, which is not preferable. More preferably, it is 15 mm or less.
[0020]
In the present invention, the surface material b has a thickness of at least part or all within a range of 0.02 mm to 4 mm. If the thickness is smaller than 0.02 mm, the rigidity of the surface member alone is small. For example, when a ball such as a golf ball or a stone roller hits the surface of the sandwich structure member, a problem of penetrating the surface material is not preferable. If it is larger than 4 mm, not only is the problem with the contact with other parts, but the density of the surface material is very large with respect to the density of the core material, so it is not possible to promote weight reduction of the sandwich structure member. Absent. More preferably, it is 0.1 mm or more and 3 mm or less.
[0021]
In the urethane foam core material a constituting the sandwich structure member of the present invention, the ratio (A / B) of the shear strength (A) at 100 ° C. to the shear strength (B) at 23 ° C. is 0.5 or more and 0. .95 or less. If it is less than 0.5, the structural member design may increase the density of the urethane foam core material a or increase the thickness of the foam in order to supplement the overall strength at 100 ° C. This is not preferable because the weight as a whole increases and the merit of weight reduction is lost with respect to a structural member made of a metal plate. The ratio of the shear strength at 100 ° C. to the shear strength at 23 ° C. is closer to 1, the higher the reliability as the material, and in the structural member used under a high temperature environment up to 100 ° C. This is preferable because there is no significant increase in weight.
[0022]
The urethane foam core material a in the present invention is a urethane foam core material obtained from an organic polyisocyanate, a polyol, water and / or a foaming agent, a catalyst, a foam stabilizer and other auxiliaries. The bond ratio (urea bond / urethane bond) is preferably 0.133 or more and 0.801 or less. If it is less than 0.133, the resin softening point (Tan δ value in dynamic viscoelasticity measurement) is less than 150 ° C., leading to a decrease in physical properties at high temperatures. On the other hand, if it exceeds 0.801, the releasability is lowered, and the surface quality of the foam is lowered, which is not preferable. By improving the surface quality of the urethane foam core material, when molding the sandwich structure member using the obtained urethane foam, the resin used for the surface material, the adhesive that bonds the surface material, etc. are urethane Get good design and structural surface by preventing entry into voids on the foam surface, dents called sinks on the surface, or maintaining uniform adhesion. be able to.
[0023]
The surface material b of the sandwich structure member is preferably a fiber reinforced composite material. The fibers constituting the fiber reinforced composite material include polyaramid, nylon 6, nylon 66, vinylon, billidene, polyester, polyvinyl chloride, polyethylene, polypropylene, polyurethane, acrylic, polyaramid, polyether ether ketone, polyether ketone, and polyether. Organic fibers such as imide, polyparaphenylene benzobisoxador, polybenzobisoxador, polygrillamide, vinylon, PBT, PVA, PBI, PPS, and inorganic fibers such as carbon fiber, glass fiber, and silicon carbide fiber However, any fiber can be used as long as sufficient overall rigidity can be obtained in the actual product shape. Among them, inorganic fibers such as carbon fiber, glass fiber, and silicon carbide fiber have high heat resistance. Fiber bullet Since high rate, in designing the sandwich structure member, it is possible to promote weight preferred.
[0024]
Moreover, it is preferable that carbon fiber is used as at least a part of the surface material as the reinforcing fiber of the surface material b. Since carbon fiber has a high elastic modulus not found in other fibers, it is possible to exert a sufficiently high elastic modulus simply by using carbon fiber as a part of the surface material b. The most lightweight can be promoted.
[0025]
As the resin constituting the fiber reinforced composite material of the surface material b, thermosetting resins such as epoxy resins, unsaturated polyester resins, phenol resins, vinyl ester resins, polyurethane resins, modified epoxy resins, nylon resins, acrylic resins , Polyester resins, polycarbonate resins, polyethylene resins, polypropylene resins, polyamide resins, ABS resins, polyvinyl chloride resins, polybutylene terephthalate resins, polyacetal resins, polyurethane resins and the like, and modified resins obtained by alloying these resins Any resin may be used.
[0026]
The shear modulus at 100 ° C. of the urethane foam core material a is preferably 1 MPa or more and 200 MPa or less. The three-point bending deflection δ of the sandwich structure member is expressed by the tensile elastic modulus of the surface material b and the shear elastic modulus of the urethane foam core material a as shown in the following equation (1).
[0027]
[Expression 1]

[0028]
Where P is the bending load, l is the span distance, E_fIs the tensile modulus of the surface material, t_fIs the thickness of the surface material, b is the width of the core material, G_cIs the shear modulus of the core material, and tc is the thickness of the core material. As is apparent from the second term on the right side of this equation, the bending deflection of the sandwich structure member greatly depends on the shear elastic modulus of the core material. Here, when the shear modulus of the core material is smaller than 1 MPa, when traveling in a high temperature environment, the vehicle body is deformed by the wind received by the vehicle when traveling on the transportation device, and the vehicle body resistance is increased. Furthermore, due to the air resistance received by the vehicle body, the vibration of the vehicle body increases, so that the running stability is deteriorated and the comfort in the vehicle cannot be obtained. The higher the shear modulus, the higher the overall rigidity of the sandwich structure member, which is preferable because it can promote weight reduction. When it is 10 to 160 MPa, the contribution of the core material to the deflection generated by the bending stress of the sandwich structure member is sufficiently small, and the breakage at the core material portion is extremely reduced, which is further preferable.
[0029]
  The shear strength of urethane foam core material a at 100 ° C is0.01It is preferable that it is 10 to 10 MPa.0.01If the pressure is less than MPa, when a person leans against the sandwich structure member in a high temperature environment, a very large shear deformation occurs in the core material portion, and the interlaminar shear failure of the core material or the load direction of the core material is 45%. It is not preferable because breakage occurs inside the core material, such as breakage that cracks in the direction of °. Since such a break is a break inside the sandwich structure member and is not visible, there is a problem that the place where the break is occurring cannot be specified and cannot be repaired. When using a foam with such a low shear strength as the core material, there is a method to increase the thickness of the high-density surface material in order to reduce the deflection of the sandwich structure member as much as possible. It is not preferable because it increases. The higher the shear strength at 100 ° C, the more lightweight the sandwich structure member can be designed.Yes.
[0030]
  CThe density of the foamed foam core material a (the density of the foam is measured according to JIS K 7222) is 0.01 g / cm.^Three0.3 g / cm^ThreeIsAnd preferred.0.01 g / cm^ThreeIf it is smaller, the thickness of the cell walls (referred to as cells) constituting the urethane foam becomes extremely thin and the rigidity becomes insufficient. 0.3 g / cm^ThreeIf it is larger, the weight reduction effect cannot be obtained for the core material for sandwich structures of aircraft and ships, which is the conventional technology, that is, the honeycomb material made of aluminum or nomex paper, or lightweight wood such as balsa. Absent. More preferably, 0.025 to 0.24 g / cm^ThreeIt is.In the present invention, in order to make the above-mentioned “problem to be solved by the invention” “urethane foam can promote further weight reduction of a sandwich structure member having high rigidity”, the above-mentioned 0. 025 to 0.24 g / cm ^Three The density range is adopted.
[0031]
  The closed cell ratio of the urethane foam core material a is preferably 75% or more.However, in the present invention, it is specified that the closed cell ratio is 93% or more, in which good results were actually obtained in the examples described later.Sandwich structural members are drilled to join other parts, and the urethane foam part, which is the core material, may be exposed to the external environment.ButIf it is small, when exposed to a high humidity environment or rainy environment, moisture is taken into the open cell portion of the core material, and the urethane foam core material a softens, resulting in undulations on the surface of the sandwich structure member. It is not preferable because it will come out. Furthermore, since the core material of the sandwich structure member is wrapped by the surface material, the absorbed moisture hardly volatilizes, and the weight of the sandwich structure member increases with time.Yes.
[0032]
  Also, closed cell rateButIf it is small, the resin that becomes the adhesive layer impregnates the inside of the foam, so that there is no adhesive layer between the surface material and the core material, and the adhesive strength may be very weak. Moreover, when the resin or adhesive is impregnated into the foam in this way, the resin present on the surface of the sandwich structure member is reduced, and there is no surface smoothness, resulting in a rough surface form.
[0033]
Hereinafter, the urethane foam used for the urethane foam core material will be described more specifically.
Urethane foam is a urethane foam composed of organic polyisocyanate, polyol, water and / or foaming agent, catalyst, foam stabilizer and other auxiliaries, with excellent dimensional stability and good surface quality. Yes, it is a urethane foam suitable as a core material for sandwich structure members. Hereinafter, first, each component used for these manufacture and the manufacturing method of urethane foam are demonstrated in detail.
[0034]
(Organic polyisocyanate)
As an isocyanate compound used for this invention, if it uses for manufacture of a polyurethane, it can be used. These isocyanates may be used alone or in combination of two or more, and modified products such as nurate modification, prepolymer modification and uretdione modification may be used, and a plurality of polyisocyanates and modified products may be used in combination. May be.
[0035]
Examples of the aliphatic polyisocyanate compound include 1,6-diisocyanatohexane (HDI).
[0036]
As the alicyclic polyisocyanate compound, 2,5- or 2,6-bisisocyanatomethyl-bicyclo [2,2,1] heptane (NBDI), 3,3,5-trimethyl-1-isocyanato-5 Isocyanatomethylcyclohexane (IPDI), 1,6-bisisocyanatomethylcyclohexane (H₆-XDI), 1,6-diisocyanatohexane (HDI), bis (4,4'isocyanatocyclohexyl) methane (H₁₂-MDI).
[0037]
Specific examples of compounds in which at least two isocyanate groups are directly bonded to an aromatic group include 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate ( 2,4′-MDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI) and their dimers, trimers or Examples include multimers, or mixtures thereof, crude TDI, crude MDI, and mixtures thereof.
[0038]
Examples of the isocyanate compound having at least two NCO groups that are not directly bonded to the aromatic group include 1,6-bisisocyanatomethylbenzene (XDI).
[0039]
In the present invention, a diphenylmethane diisocyanate derivative can be suitably used as the organic polyisocyanate. The diphenylmethane diisocyanate derivative has an aromatic ring in the molecular skeleton, has a high aromatic ring concentration in the molecule, and has good heat resistance. Furthermore, a urethane foam is also preferable because it can suppress deterioration of physical properties at high temperatures. In addition, diphenylmethane diisocyanate derivative compounds and mixtures thereof that are liquid at normal temperature are easy to handle and more suitable.
[0040]
The amount of the organic polyisocyanate used in the production of the foam is almost the same as in the case of a normal urethane foam, and the NCO / OH (molar ratio) is preferably 0.7 to 5.0, more preferably Is 1.0 to 3.0, particularly preferably 1.0 to 1.4.
[0041]
(Polyol)
Examples of the polyol compound in the present invention include known ones used for the production of urethane foams such as polyether polyols, polyester polyols, and polymer polyols, with polyether polyols being particularly preferred. Polyether polyol is a compound having two or more hydroxyl groups in the molecule, with alkylene oxide added, and having a hydroxyl value of 350 mgKOH / g with propylene oxide added to a sorbitol / water / tolylenediamine / triethanolamine mixture. Polyols are preferred. Other than that, for example, ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexane glycol, glycerin, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, pentaerythritol, sorbitol, Obtained by addition polymerization of alkylene oxide to single or mixed systems of polyhydric alcohols such as sucrose, aromatic amines such as tolylenediamine, and aliphatic amines such as ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine Examples include polyether polyols having a hydroxyl number of 200 to 500 mg KOH / g. Here, examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and styrene oxide.
[0042]
Polyester polyols that can be used are all known, but a hydroxyl number of 200-500 mgKOH / g produced from aliphatic polybasic acids, aromatic polybasic acids and anhydrides thereof and polyhydric alcohols. Examples include polyester diol and polyester triol. Examples of the aliphatic polybasic acid and its anhydride include oxalic acid, malonic acid, adipic acid, succinic acid, and succinic anhydride. Examples of the aromatic polybasic acid and its anhydride include terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Examples of polyhydric alcohols are those having 2 to 8 functional groups such as ethylene glycol, propylene glycol, butanediol, propanediol, diethylene glycol, trimethylpentanediol, glycerin, and pentanediol. , Sorbitol, sucrose, and alkylene oxide adducts of these polyhydric alcohols can be used. In addition, compounds obtained by addition polymerization of alkylene oxide to these polyester polyols can also be used. Further, a product obtained by thermally decomposing polyalkylene terephthalate or its residue in a polyol or polycaprolactone copolyester polyol can be used.
[0043]
The polymer polyol is obtained by dispersing polyacrylonitrile, polystyrene, polyurea or the like in the aforementioned polyether polyol. These polyether polyols, polyester polyols, and polymer polyols may be used in combination. The number of functional groups of these or a mixed polyol is preferably 2 or more, 8 or less, more preferably 3 or more and 6 or less, and particularly preferably 4 or more and 5 or less.
[0044]
In the present invention, polyether polyols having good surface quality during molding can be suitably used. Their hydroxyl value is preferably 200 to 500 mgKOH / g, more preferably 300 to 400 mgKOH / g, and the number of functional groups is particularly 4 or more and 5 or less from the mechanical strength of the obtained foam. preferable.
[0045]
(Foaming agent)
As the foaming agent in the present invention, water, carbon dioxide gas, hydrocarbons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) can be used as long as they can be used for the production of urethane foams. And hydrofluoroethers (HFEs). These foaming agents may be used alone or in combination. For example, low boiling point hydrocarbons such as water and carbon dioxide, water and methane, ethane, propane, pentane, isopentane, and cyclopentane, water and halogenated hydrocarbons, and the like can be used in combination.
[0046]
In the present invention, it is particularly preferable to use a foaming agent having a low environmental load such as water and carbon dioxide. Water is used as a blowing agent by reacting with a polyisocyanate to generate carbon dioxide, and usually ion-exchanged water or distilled water is used, but industrial water can be used as it is. The amount of water can be 0.5 to 10 parts by weight, more preferably 1.0 to 9.5 parts by weight, per 100 parts by weight of the total polyol component.
[0047]
In the present invention, the ratio of urea bond to urethane bond (urea bond / urethane bond) is 0.133 or more and 0.801 or less in order to suppress deterioration of mechanical properties at high temperature in the obtained foam. From these points, the amount of water used as a blowing agent is particularly preferably 1.5 to 9.0 parts by weight per 100 parts by weight of the total polyol component.
[0048]
(catalyst)
As the catalyst, all known catalysts usually used for urethane foaming can be used. For example, trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine, diazobicycloundecene, 1,3,5-tris (Dimethylaminopropyl) triazines such as hexahydro-s-triazine, amine compounds such as aziridines such as 2-ethylaziridine, quaternary ammonium compounds such as carboxylates of tertiary amines, allyl glycidyl ethers, polyalkylene glycols Alkali metal salts such as diglycidyl ether and styrene oxide, lead compounds such as lead naphthenate and lead octylate, tin compounds such as dibutyltin diacetate and dibutyltin dilaurate, sodium methoxide Alcoholate compounds such as de, phenolate compounds such as potassium phenoxide, iron chloride, zinc chloride, zinc bromide, metal halides such as tin chloride, can be mentioned metal complex compounds such as acetylacetone metal salts. These catalysts can be used alone or in combination of two or more, and the amount used is suitably 0.001 to 15.0 parts by weight per 100 parts by weight of polyol. Although depending on the process at the time of manufacture, in consideration of product quality acquisition and productivity, organic amines which are relatively safe in handling and contain no metal content in the foam even after the foam is produced are reduced to 0. It is particularly preferable to use in the range of 1 to 5 parts by weight.
[0049]
(Foam stabilizer)
As the foam stabilizer, a conventionally known silicon-containing organic surfactant is used. For example, SZ-1127, SZ-1142, SZ-1605, SZ-1642, SZ-1649, SZ-1655, L-580, L-5740, L-5420, L-5421, etc. manufactured by Nippon Unicar Co., Ltd. SF-2935F, SF-2938F, SF-2940F, SF-2945F, SF-2908, SRX-294A, SH-190, SH-192, SH-193, etc., manufactured by Toray Dow Corning Silicone Co., Ltd., Shin-Etsu F-327, F-345, F-305, X-20-1328, etc. manufactured by Chemical Industry Co., Ltd. are suitable. The amount of these foam stabilizers used is 0.01 to 10 parts by weight with respect to 100 parts by weight of the total of the polyol and the organic polyisocyanate. From the economical point, it is particularly preferable to use in the range of 0.01 to 5 parts by weight.
[0050]
(Additives for other polyurethane production)
In the present invention, auxiliary agents such as a cocatalyst, a flame retardant, a plasticizer, a stabilizer, a filler, and a colorant can be added as necessary. Examples of the cocatalyst include carbonate compounds such as ethylene carbonate and propylene carbonate, and phosphoric acid compounds such as phosphate esters and phosphites. Examples of the flame retardant include tris (chloropropyl) phosphate, which is usually used when manufacturing heat-insulating polyurethane foam for homes and building materials.
[0051]
(Method for producing urethane foam)
The urethane foam production method according to the present invention is produced as follows. The organic polyisocyanate and the polyol are preferably mixed immediately before foaming. Other blowing agents, catalysts and foam stabilizers, and auxiliary agents to be used as appropriate are generally pre-mixed with polyisocyanate or polyol as necessary, and these mixtures can be used immediately after mixing or stored. However, the necessary amount may be used as appropriate. The mixing of other components can determine the combination of the mixing, the mixing order, the storage time after mixing, and the like as necessary.
[0052]
Of such mixtures, a mixture of polyol and other components, that is, a mixture of polyol and other additives used as necessary, such as a foaming agent, a catalyst, and a foam stabilizer, may be referred to as a resin premix. . These compositions can be appropriately set depending on the required quality of the urethane foam. This resin premix is reacted with a polyisocyanate.
[0053]
The polyisocyanate may be unmodified, modified, or a mixture thereof. The viscosity of the resin premix to be used is preferably 2,500 mPa · s / 25 ° C. or less from the viewpoint of the mixing property in the foaming machine and the moldability of the urethane foam.
[0054]
As a mixing method, any apparatus can be used as long as the organic polyisocyanate and the resin premix can be mixed uniformly. For example, you may use the mixing method by any of collision mixing and stirring mixing. As the collision mixing device, a general high-pressure foaming machine for producing urethane foam can be used. Moreover, as a stirring mixing apparatus, a low pressure foaming machine for a small mixer and general urethane foam manufacture can be used, for example. The mixing temperature and pressure can be arbitrarily set as required depending on the quality of the desired urethane foam, the type and composition of the raw material, and can be heated as necessary prior to mixing.
[0055]
The ratio of isocyanate groups to active hydrogen groups (NCO / OH equivalent ratio) is in the range of 0.7 to 5.0, preferably in the range of 1.0 to 3.0, and in the range of 1.0 to 1.4. Is particularly preferred. It is preferable to set the NCO / OH equivalent ratio to 0.5 or less because a superior surface quality can be expressed.
[0056]
  Moreover, in the obtained foam, in order to suppress deterioration of mechanical properties at high temperature, the ratio of urea bond to urethane bond (urea bond / urethane bond) may be designed to be 0.133 or more and 0.801 or less. Particularly preferred. The ratio of urea bond to urethane bond (urea bond / urethane bond) is 0.133more thanThen, the resin softening point (Tan δ value in dynamic viscoelasticity measurement) is 150 ° C. or more, which is preferable because the physical properties at high temperatures can be kept higher. Moreover, the surface quality of a foam can be made more excellent by setting it as 0.801 or less.
[0057]
As a foaming method, any known molding technique such as slab, mold foaming, injection foaming, spray foaming, and laminate foaming may be used. At the time of foaming, organic polyisocyanate and resin premix are mixed at a liquid temperature of 15 to 80 ° C., preferably 20 to 50 ° C., and the temperature can be controlled as necessary under normal pressure or in some cases reduced pressure or high pressure. A suitable urethane foam can be obtained by introducing it into a mold.
[0058]
The sandwich structure member having the urethane foam of the present invention as a core material is used as a core material for sandwich structure members of transportation equipment such as automobiles, high-speed vehicles, high-speed boats, single cars, bicycles, aircrafts, refrigerators, temperature controllers, speakers. It can be suitably used as a core material for sandwich heat insulating structural members of building materials such as electrical appliances such as wind turbines, low-temperature warehouses, refrigerated warehouses, low-temperature test room barns, silos, buildings, houses, and factories. Specifically, as sandwich structure members for transportation equipment, automobile members such as doors, bonnets, fenders, trunk lids, hard tops, side mirror covers, platforms, and vehicles such as leading vehicle noses, roofs, side panels, doors, etc. Parts, wing inner panels, outer panels, roofs, floors, aero parts such as air spoilers and side skirts to be mounted on cars and motorcycles, frames, handles, speed change levers, brake bars, front hubs, etc. Bicycles such as cranks, freehubs, derailleurs, seat pillars, and saddles. Moreover, as an electrical appliance, it can use suitably also as heat insulation members, such as a heat insulation board, an outer wall material, an interior material, a tank, and piping, as a heat insulation and sound insulation members, such as a refrigerator and a temperature controller, and a building material.
[0059]
Hereinafter, the present invention will be specifically described based on examples. In Examples and Comparative Examples, preparation of various samples and measurement of physical property values were performed under the following conditions.
[0060]
(Creation of urethane foam)
(Raw materials used)
Organic polyisocyanate A: Cosmonate M-200 (Organic polyisocyanate manufactured by Mitsui Takeda Chemical Co., Ltd. NCO% = 31.4%).
Polyol X: Polyol A, Polyol B, and Polyol C described below in a mixed polyol ratio of 28:12:60 (polyol manufactured by Mitsui Takeda Chemical Co., Ltd., hydroxyl value 350 mgKOH / g)
Polyol A: A polyol having a hydroxyl value of 350 mgKOH / g obtained by adding propylene oxide to pentaerythritol at a reaction temperature of 110 ° C. using potassium hydroxide as a catalyst. Polyol B: A polyol having a hydroxyl value of 350 mgKOH / g obtained by adding propylene oxide to a 70:30 weight ratio mixture of tolylenediamine and triethanolamine at a reaction temperature of 110 ° C. using potassium hydroxide as a catalyst.
Polyol C: A polyol having a hydroxyl value of 350 mgKOH / g, obtained by adding propylene oxide to a 97: 3 weight ratio mixture of sorbitol and water at a reaction temperature of 110 ° C. using potassium hydroxide as a catalyst.
Catalyst A: Kaulizer No. 10 (N, N-dimethylcyclohexylamine manufactured by Kao Corporation).
Silicone foam stabilizer A: X-20-1328 (polydimethylsiloxane derivative manufactured by Shin-Etsu Chemical Co., Ltd.).
Foaming agent A: Alternative Freon HCFC-141b (manufactured by Daikin Industries, Ltd., 1,1-dichloro-1-fluoroethane)
[0061]
(Foaming method)
Foaming was performed as follows. 2 parts by weight of silicone foam stabilizer A per 100 parts by weight of polyol X, a predetermined amount of water and / or physical foaming agent (hydrocarbons, halogenated hydrocarbons), catalyst for obtaining urethane foam of desired density Add organic polyisocyanate A so that the NCO / OH equivalent ratio is 1.1 and add it to the liquid in which the necessary amount for A to have a gel time of 80 ± 5 seconds is used. Mix at 6,000 rpm for about 6 seconds and quickly pour this mixture into a wooden box without lid, 300 mm wide, 300 mm long and 300 mm high, cure at room temperature, and 15 minutes after injection from the mold The urethane foam was taken out.
[0062]
(Measurement of density of urethane foam)
A test piece having a width of 95 mm, a length of 95 mm, and a thickness of 95 mm was cut out from the urethane foam obtained by the above method using a slitter the next day, and the free density (apparent density) inside the foam was measured in accordance with JIS K7222.
[0063]
(Measurement of closed cell ratio of urethane foam)
The urethane foam obtained by the above method was cut out with a slitter the following day with a 25 mm width, 25 mm length, and 35 mm thickness test piece, and the method used for measuring the closed cell ratio of a rigid polyurethane foam was followed. Specifically, it is an apparent volume ratio (%) measured by the method described in ASTM D-2856 using an “pneumatic apparent volume measuring device”. The closed cell ratio according to the present invention is a value measured using a Toshiba Beckman air hydrometer model 930.
[0064]
(Measurement of shear strength and elastic modulus of urethane foam)
A test piece having a width of 50 mm, a length of 150 mm, and a thickness of 10 mm was cut out from the urethane foam obtained by the above method in accordance with ASTM C273, and the shear modulus was measured. In the measurement under a high temperature environment, the measurement was performed in an oven at 100 ° C.
[0065]
(Creation of sandwich structure member)
FIG. 2 is a plan view of a composite material and a manufacturing apparatus for manufacturing the fiber-reinforced composite material of the present invention.
First, these drawings will be explained before explaining a method for producing a sandwich structure member. In FIG. 2, 1 is an aluminum plate used as a rigid single-sided mold. 2 is a glass fiber fabric used as a breather (breathing material), 3 is a carbon fiber fabric as a reinforcing fiber substrate, 4 is a urethane foam as a core material, and 6 is a peel ply (a covering material for facilitating peeling) The polyester taffeta 7 used as a plastic mesh is a plastic mesh which is a resin diffusion medium. Reference numerals 9 and 12 are aluminum channels for sucking air (including resin) and for injecting matrix resin, respectively. A matrix resin can be injected from a path A, which is a connection path to a matrix resin container (not shown). Air can be sucked from the reinforcing fiber 2 to the resin diffusion medium 7 part to the B path which is a connection path. The suction path B is provided with a trap (not shown) to remove the sucked resin. Reference numeral 13 denotes a silicone sealant for preventing air from flowing in from the outside during decompression, 8 is a nylon film used as a flexible film, and 10 and 11 are an air suction port and a matrix resin injection port, respectively. This is a polyethylene tube.
[0066]
In FIG. 2, a fiber reinforced composite material was prepared by the RTM method (resin transfer molding method) using a rigid single-sided mold, a flexible film, and a resin diffusion medium. A specific manufacturing procedure is shown below.
[0067]
A 500 mm × 500 mm plate was used as the aluminum plate 1 in FIG. 2, and a mold release agent (GA-6010 manufactured by Daikin Industries, Ltd.) was sprayed on the surface to be molded. On one side of the aluminum plate 1, a tape-like material was placed as the glass fiber fabric 2 in parallel. Fabric cut out to 350 mm in length and 350 mm in width as carbon fiber fabric 3 (CK6243C manufactured by Toray Industries Inc., carbon fiber type: T700S, organization: plain weave, basis weight: 300 g / m²) Were placed so that one side slightly overlapped with the glass fiber fabric 2. The urethane foam 4 having a length of 300 mm, a width of 300 mm, and a height of 300 mm created above as the urethane foam 4 is cut out to a height of 10 mm, and then the depth is formed on one surface of the urethane foam 4 as shown in FIG. A groove having a width of 2 mm and a width of 1 mm was processed at a pitch of 30 mm, and placed on the carbon fiber fabric 3 so that the processed surface of the groove C could not be seen. Subsequently, a woven fabric cut to a length of 370 mm and a width of 370 mm as a carbon fiber fabric 5 (CK6243C manufactured by Toray Industries, Inc., carbon fiber type: T700S, organization: plain weave, basis weight: 300 g / m²The three sheets were placed on the urethane foam 4 so as to cover the carbon fiber fabric 3. The carbon fiber fabric was covered with a polyester taffeta 6 cut out slightly larger than the carbon fiber fabric 5. In addition, a plastic mesh 7 (TSI-160 manufactured by Mitsui Petrochemical Co., Ltd.) was placed as a resin diffusion medium so that the carbon fiber fabric 5 covered a portion where the glass fiber fabric 2 did not overlap. Then, an aluminum channel 9 is placed on the glass fiber fabric 2 as a suction path for air and resin, and another aluminum channel 12 is placed near the side of the plastic mesh 7 facing the glass fiber fabric 2 as a resin injection path. It was. A silicone sealant 13 was placed around the aluminum plate 1 and the whole was covered with a nylon film 8. Then, a nylon film 8 covering the end face of the aluminum channel 9 placed on the glass fiber fabric 2 is perforated, a polyethylene tube 10 is inserted into this, and a portion where the tube 10 and the film 9 are in contact is sealed with a silicone sealant, A suction port was used. Further, a polyethylene tube 11 was similarly inserted into the aluminum channel 12 side placed on the plastic mesh 5 to form an injection port.
[0068]
2 is installed on a hot plate, the tube 11 on the resin inlet side is connected to a container with a hot water jacket of the epoxy resin composition, and the tube 10 on the suction port side is connected through a glass trap and a valve. Connected to a vacuum pump, and the resin container and the entire apparatus were heated to 40 ° C. A vacuum pump (not shown) was operated and sucked to inject the epoxy resin composition into the mold. After visually confirming that the epoxy resin composition fills the mold and no bubbles are observed in the epoxy resin composition flowing out to the trap, close the valve and cut the tube on the inlet side and suction side. The apparatus was transferred into a hot air oven at 40 ° C. The oven was heated to 90 ° C. at a heating rate of 1.5 ° C./min, and was cured at 90 ° C. for 3 hours. After curing, the device was disassembled and the fiber reinforced composite plate was taken out, and the plastic mesh and polyester taffeta were peeled off.
[0069]
As the epoxy resin composition, 25.0 parts by weight of Celoxide 2021P (Epoxy resin manufactured by Daicel Chemical Industries, Ltd.), 75.0 parts by weight of ERL-4299 (Epoxy resin manufactured by Union Carbide Japan Co., Ltd.), diethylene glycol (Wako Pure) 9.6 parts by weight of Yakuhin Kogyo Co., Ltd., 0.1 parts by weight of SEESORB 704 (manufactured by Sipro Kasei Co., Ltd., UV absorber), 91% Rikacid MH-700 (acid anhydride manufactured by Shin Nippon Rika Co., Ltd.) .3 parts by weight and 5.7 parts by weight of Curesol 1,2-DMZ (imidazole manufactured by Shikoku Chemicals Co., Ltd.) were prepared to obtain an epoxy resin composition.
[0070]
The obtained sandwich structure member had no voids on the surface.
(Measurement of shear strength of sandwich structural members)
From the sandwich structure member obtained by the above method, in accordance with ASTM C273, a test piece was cut out to a size of 25 mm in width, 150 mm in length, and the actual thickness of the molded product, and subjected to a lap shear test at 100 ° C. and 23 ° C. The shear strength of the structural member was measured. Here, when the sandwich structure member was cut out, it was carefully cut so that the groove portion did not enter the sample. Thereafter, the value of shear strength at 100 ° C./shear strength at 23 ° C. obtained from this was calculated.
[0071]
【Example】
Example 1
A mixture of 0.8 parts by weight of catalyst A, 2 parts by weight of silicone foam stabilizer A, and 5 parts by weight of water with respect to 100 parts by weight of polyol X has an NCO / OH equivalent ratio of 1.1. Add 173.5 parts by weight of organic polyisocyanate A, mix at about 6000 rpm for about 6 seconds using a high-speed rotating lab stirrer at a liquid temperature of 25 ° C. After quickly pouring into a wooden box without a lid and curing at room temperature, it was removed from the mold 15 minutes after injection to make a urethane foam. The (urea bond / urethane bond) ratio at this time is 0.445.
[0072]
When the density, shear strength, and shear modulus of the molded urethane foam were measured by the methods described above, the density was 0.07 g / cm.^ThreeThe closed cell ratio was 93%, the shear strength at 23 ° C. was 0.1 MPa, the shear strength at 100 ° C. was 0.05 MPa, and the ratio of shear strength at 100 ° C./shear strength at 23 ° C. was 0.00. It was 5. The shear modulus of the core material at 100 ° C. was 5 MPa.
[0073]
Next, a sandwich structure member was molded by the above-mentioned method using this urethane foam as a core material, and the shear strength of the sandwich structure member was measured by the above-mentioned method. The shear strength value at 100 ° C./the shear strength at 23 ° C. Was 0.55.
[0074]
(Reference example 1)
  An NCO / OH equivalent ratio of 1. is obtained by mixing 0.8 parts by weight of catalyst A, 2 parts by weight of silicone foam stabilizer A, and 1.5 parts by weight of water with respect to 100 parts by weight of polyol X. A urethane foam was prepared in the same manner as in Example 1 except that 116.3 parts by weight of organic polyisocyanate A was added so as to be 1. The (urea bond / urethane bond) ratio at this time is 0.134.
[0075]
When the density, shear strength, and shear modulus of the molded urethane foam were measured by the methods described above, the density was 0.26 g / cm.^ThreeThe closed cell ratio is 94%, the shear strength at 23 ° C. is 13.5 MPa, the shear strength at 100 ° C. is 9.5 MPa, and the ratio of shear strength at 100 ° C./shear strength at 23 ° C. is 0.00. 7. The shear modulus of the core material at 100 ° C. was 150 MPa.
[0076]
Next, a sandwich structure member was molded by the above-mentioned method using this urethane foam as a core material, and the shear strength of the sandwich structure member was measured by the above-mentioned method. The shear strength value at 100 ° C./the shear strength at 23 ° C. Was 0.8.
[0077]
(Comparative Example 1)
A solution in which 0.8 parts by weight of catalyst A, 2 parts by weight of silicone foam stabilizer A, 1.0 part by weight of water, and 26.0 parts by weight of blowing agent A are mixed with 100 parts by weight of polyol X. A urethane foam was prepared in the same manner as in Example 1 except that 108.1 parts by weight of organic polyisocyanate A was added so that the NCO / OH equivalent ratio was 1.1. The (urea bond / urethane bond) ratio at this time is 0.089.
[0078]
When the density, shear strength, and shear modulus of the molded urethane foam were measured by the methods described above, the density was 0.07 g / cm.^ThreeThe closed cell ratio was 89%, the shear strength at 23 ° C. was 0.08 MPa, the shear strength at 100 ° C. was 0.009 MPa, and the ratio of shear strength at 100 ° C./shear strength at 23 ° C. was 0.00. 1 Further, the shear modulus of the core material at 100 ° C. was 0.9 MPa.
[0079]
Next, a sandwich structure member was molded by the above-mentioned method using this urethane foam as a core material, and the shear strength of the sandwich structure member was measured by the above-mentioned method. The shear strength value at 100 ° C./the shear strength at 23 ° C. Was 0.1.
[0080]
(Comparative Example 2)
For 100 parts by weight of polyol X, 0.8 part by weight of catalyst A, 2 parts by weight of silicone foam stabilizer A, 1.0 part by weight of water, and 3.2 parts by weight of blowing agent A were mixed. A urethane foam was prepared in the same manner as in Example 1 except that 108.1 parts by weight of organic polyisocyanate A was added to the solution so that the NCO / OH equivalent ratio was 1.1. The (urea bond / urethane bond) ratio at this time is 0.089.
[0081]
When the density, shear strength, and shear modulus of the molded urethane foam were measured by the methods described above, the density was 0.26 g / cm.^ThreeThe closed cell ratio is 90%, the shear strength at 23 ° C. is 11 MPa, the shear strength at 100 ° C. is 3.3 MPa, and the ratio of shear strength at 100 ° C./shear strength at 23 ° C. is 0.3. there were. The shear modulus of the core material at 100 ° C. was 85 MPa.
[0082]
Next, a sandwich structure member was molded by the above-mentioned method using this urethane foam as a core material, and the shear strength of the sandwich structure member was measured by the above-mentioned method. The shear strength value at 100 ° C./the shear strength at 23 ° C. Was 0.45.
The above results are summarized in Table 1.
[0083]
[Table 1]

[0084]
  As shown in Table 1, Example 1Reference example 1Have a (urea bond / urethane bond) ratio of 0.445 and 0.134, and by using such a urethane foam as a core material of a sandwich structure member, shear strength at 100 ° C./23° C. The ratio of the shear strength at 0.55 and 0.8 was able to be reduced. At this time, the ratio of the shear strength at 100 ° C./the shear strength at 23 ° C. of the urethane foam core material was 0.5 and 0.7.In particular, in Example 1, as shown in Table 1, the density of the molded core material is 0.07 g / cm. ^Three Reference Example 1 (Density of molded core: 0.26 g / cm ^Three ) Can be further reduced in weight.
[0085]
On the other hand, in Comparative Examples 1 and 2, the (urea bond / urethane bond) ratio is 0.089, and such urethane foam is used as the core material of the sandwich structure member, and the shear strength at 100 ° C. The ratio of shear strength at / 23 ° C. was 0.1 and 0.45, and the reduction rate was large. At this time, the ratio of the shear strength at 100 ° C./the shear strength at 23 ° C. of the urethane foam core material was 0.1 and 0.3.
[0086]
【The invention's effect】
As described above, according to the sandwich structure member of the present invention, it is lightweight and can increase the shear strength and shear modulus under a high temperature environment. In addition, the urethane foam used in the present invention can not only promote further weight reduction of the sandwich structure member, but also can withstand localized concentrated loads in a high temperature environment, so that transportation of automobiles, vehicles, airplanes, etc. It can be suitably applied as a structural member for equipment.
[Brief description of the drawings]
FIG. 1 is a schematic partial cross-sectional view of a sandwich structure member of the present invention.
FIG. 2 is a plan view showing a composite material during manufacturing the sandwich structure member of the present invention and a partially broken portion of the manufacturing apparatus.
FIG. 3 is a perspective view showing an example of a core material used for manufacturing the sandwich structure member of the present invention.
[Explanation of symbols]
a Core material
b Surface material
1 Aluminum plate
2 Glass fiber fabric
3 Carbon fiber fabric
4 Urethane foam
5 Carbon fiber fabric
6 Polyester taffeta
7 Plastic mesh
8 Nylon film
9 Aluminum channel
10 Polyethylene tubing
11 Polyethylene tube
12 aluminum channels
13 Silicone sealant
A Connection path to resin container
B Connection path to vacuum pump
C groove

Claims (6)

A core material made of urethane foam having a thickness of at least part or all of 20 mm or less as the core material, and a surface material of the core material, wherein the thickness of at least part or all is in the range of 0.02 mm to 4 mm. A sandwich comprising a fiber composite material surface material and having a ratio (A / B) of a shear strength (A) at 100 ° C. to a shear strength (B) at 23 ° C. of 0.5 to 0.95 A sandwich structural member, wherein the urethane foam has a closed cell ratio of 93% or more and a density of 0.025 g / cm ³ or more and 0.24 g / cm ³ or less . The urethane foam is a urethane foam formed by combining at least one selected from organic polyisocyanates, polyols, water and / or foaming agents, catalysts, foam stabilizers and auxiliaries, wherein urea bonds and urethanes are used. ratio of binding (urea bond / urethane bond), Ru der range of 0.133 or more 0.801 or less, the sandwich structure according to 請 Motomeko 1. At least part or that contains carbon fibers in all, the sandwich structure according to 請 Motomeko 1 or 2 of the surface material. The shear modulus at 100 ° C. of the urethane foam, Ru der range of 1MPa or more 200MPa or less, sandwich structure according to any of the 請 Motomeko 1-3. The urethane foam shear strength at 100 ° C. of, Ru der in 10MPa or less the range of 0.01 MPa, the sandwich structure according to any of the 請 Motomeko 1-4. Ru is used as the automobile member, a sandwich structure according to any of the 請 Motomeko 1-5.

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