JP4544656B2 - Prepreg and fiber reinforced composites - Google Patents

Description

ここで、Ｒ₁，Ｒ₂，Ｒ₃は酸素を含み得る炭化水素基であって、Ｒ₁とＲ₃については同一であっても異なっていても良く、また炭化水素基中にビスフェノール基（−Ｏ−Ｐｈ−ＣＲ₂−Ｐｈ−Ｏ−ＣＨ₂ＣＨ（ＯＨ）ＣＨ₂−；Ｐｈ＝Ｃ₆Ｈ₄、Ｒ＝ＣＨ₃またはＨ）を含むものが一般的である。
【００２２】
オキサゾリドン環を有するエポキシ樹脂は、特開平５−４３６５５号公報に示される方法によって、３級アミン、４級アンモニウム塩、ホスホニウム化合物、リチウム化合物等の触媒存在下で、イソシアネート化合物とエポキシ化合物を反応させることにより得ることができる。イソシアネート化合物としては、イソホロンジイソシアネート、キシレンジイソシアネート、ジフェニルメタンジイソシアネート、トリレンジイソシアネート、ヘキサメチレンジイソシアネートなど、またはこれらの混合物が挙げられ、またエポキシ化合物としては、ビスフェノールＡジグリシジルエーテル、ビスフェノールＦジグリシジルエーテル、ビスフェノールＳジグリシジルエーテルなど、またはこれらの混合物が挙げられる。
【００２３】
前記テトラグリシジルアミン型エポキシ樹脂以外のエポキシ樹脂の中で、ビスフェノール型エポキシ樹脂は、補強繊維との接着性を高いまま保持しつつ、樹脂の靭性を改善するため好ましく、またノボラック型エポキシ樹脂、ジシクロペンタジエン型エポキシ樹脂は、得られる複合材料の耐熱性、耐環境性を保持しながらプリプレグのタックを適度に抑制する効果があるためテトラグリシジルアミン型エポキシ樹脂以外のエポキシ樹脂として、特に好ましく用いられる。
【００２４】
さらにまたテトラグリシジルアミン型エポキシ樹脂以外のエポキシ樹脂として、前記した、オキサゾリドン環を有するエポキシ樹脂を用いると、補強繊維との接着性がさらに高まり、圧縮強度などの強度特性、耐熱性、耐環境性がより優れた繊維強化複合材料を得ることができ好ましい。
【００２５】
なおこれらテトラグリシジルアミン型エポキシ樹脂以外のエポキシ樹脂が、前記構成要素［Ａ］に配合される量はできる限り少ない方が良いが、エポキシ樹脂配合物１００重量部に対して、３〜４０重量部、好ましくは３〜３０重量部が良く、より好ましくは３〜２０重量部が良い。
【００２６】
本発明における構成要素［Ｂ］は、粒子状ジシアンジアミド（以下、ＤＩＣＹと称する）である。本発明においては、後述する構成要素［Ｄ］のジアミノジフェニルスルホン（以下、ＤＤＳと称する）を、硬化剤としてＤＩＣＹと特定の配合量で併用することで、補強繊維とマトリクス樹脂とがより強固に接着するようになる。すなわち、エポキシ樹脂配合物１００重量部に対して、ＤＩＣＹを３〜５重量部、ＤＤＳを５〜１５重量部配合したエポキシ樹脂組成物からなる本発明のプリプレグは、補強繊維との間に顕著な接着効果を発現することによって圧縮強度などの強度特性、耐熱性、耐環境性がより優れた繊維強化複合材料を得ることができる。
【００２７】
ＤＩＣＹは、アミン系硬化剤に属する微粒子状の化合物であり、低温領域ではバルクに相当するエポキシ樹脂組成物に難溶であるが、１００℃以上になると溶解し、エポキシ樹脂との反応が開始する。このため、ＤＩＣＹを硬化剤に使用したエポキシ樹脂組成物やプリプレグは、特に貯蔵安定性が良好である。
【００２８】
ＤＩＣＹ粒子の平均粒子径は１〜１５μｍが良く、より好ましくは３〜１３μｍ、さらに好ましくは５〜１０μｍが良い。ＤＩＣＹ粒子の平均粒子径が１μｍ未満であると、ＤＩＣＹのエポキシ樹脂組成物への溶解が促進され過ぎ、室温付近の温度でも、硬化反応が進行してしまうことがあり、エポキシ樹脂組成物やプリプレグの貯蔵安定性が損なわれてまい、またＤＩＣＹ粒子の平均粒子径が１５μｍより大きいと、プリプレグを製造する際などに、補強繊維に加圧、加熱しながら樹脂と共に粒子を含浸せしめても、補強繊維束中にＤＩＣＹが進入しにくくなることで補強繊維とマトリクス樹脂との接着性が充分に発現されなくなり、成形後に圧縮強度などの強度特性に優れた複合材料を得ることができない。
【００３０】
ＤＤＳとは、芳香族アミン系硬化剤に属する微粒子状化合物であり、芳香環上のアミノ基の置換位置により、構造異性体が存在する。本発明においては、いずれの異性体も使用することができるが、異性体の種類を変えることにより、マトリクス樹脂、および得られる複合材料の特性を制御することができる。例えば、４、４’−ＤＤＳでは特に耐熱性が優れたものとなり、３、３’−ＤＤＳは特に剛性が優れたものになる。ＤＤＳの平均粒子径は、ＤＩＣＹと同様な理由により、１〜１５μｍが良く、より好ましくは５〜１３μｍ、さらに好ましくは８〜１３μｍが良い。
【００３１】
本発明における構成要素［Ｃ］は、ウレア化合物である。ウレア化合物を硬化促進剤として使用すると、貯蔵安定性と、補強繊維との接着性の両特性に優れたエポキシ樹脂組成物を得ることができる。ここに硬化促進剤として、ウレア化合物の代わりに、３級アミン化合物を用いると、エポキシ樹脂組成物やプリプレグの貯蔵安定性が損なわれ、イミダゾール化合物を用いると、補強繊維とマトリクス樹脂との接着性が低下する傾向がある。
【００３２】
ウレア化合物としては、３−フェニル−１、１−ジメチルウレア、３−（３−クロロフェニル）−１、１、−ジメチルウレア（以下、ＤＣＭＵと称する）、３−（３、４−ジクロロフェニル）−１、１−ジメチルウレア（以下、ＨＤＩＺと称する）など、またはこれらの混合物が挙げられる。またウレア化合物の、エポキシ樹脂配合物１００重量部に対する配合量は、２〜１０重量部が良く、より好ましくは３〜８重量部、さらに好ましくは４〜６重量部が良い。ウレア化合物の配合量が２重量部未満であると、補強繊維とマトリクス樹脂との接着性が低下する傾向にあり、１０重量部を超えると、硬化促進作用が過度となってしまい、エポキシ樹脂組成物やプリプレグの貯蔵安定性が損なわれてしまう。
【００３３】
さらに本発明によるエポキシ樹脂組成物には、プリプレグにおける、樹脂が未硬化の状態におけるレオロジー特性の制御、マトリクス樹脂の剛性や靭性の向上、タックの制御、補強繊維とマトリクス樹脂との接着性向上などの改良効果をもたせるために、前述した成分のほか、次に述べる熱可塑性樹脂、エラストマー、無機粒子を改良剤として配合することが好ましい。
【００３４】
熱可塑性樹脂としては、ポリアセタール、ポリアミド、ポリアミドイミド、ポリアリーレンオキシド、ポリアリレート、ポリイミド、ポリエチレン、ポリエチレンテレフタレート、ポリエチレンナフタレート、ポリエーテルイミド、ポリエーテルエーテルケトン、ポリエーテルスルホン、ポリ塩化ビニル、ポリカーボネート、ポリ酢酸ビニル、ポリスチレン、ポリスルホン、ポリテトラフルオロエチレン、ポリヒドロキシエーテル、ポリビニルアセタール、ポリビニルアルコール、ポリビニルピロリドン、ポリビニルホルマール、ポリフェニレンオキシド、ポリブチレンテレフタレート、ポリフェニレンスルフィド、ポリプロピレン、ポリベンズイミダゾール、ポリメタクリル酸メチルなどが挙げられる。
【００３５】
これら熱可塑性樹脂は、各々単独で配合することも、また複数種を同時に配合することもできるが、中でもポリアミド樹脂は、マトリクス樹脂の靭性を改善し、得られる複合材料の耐衝撃性を向上させるため好ましく、ポリイミド樹脂およびポリエーテルスルホン樹脂は、マトリクス樹脂の剛性を高く保持したまま、補強繊維とマトリクス樹脂との接着性を強固にし、得られる複合材料の圧縮強度を大きく向上させるため、特に好ましく用いられる。
【００３６】
またこれら熱可塑性樹脂の配合量は、エポキシ樹脂配合物１００重量部に対して、５〜２０重合部が良く、より好ましくは５〜１５重量部、さらに好ましくは５〜１２重量部が良い。５重量部未満では、前記した改良効果が充分に発揮されず、２０重量部を超えると耐熱性が損なわれてしまう。
【００３７】
またエラストマーについては、液体状のものでも、固体状のものでも良いが、後者の方がマトリクス樹脂の剛性を保持する観点から、好ましく用いられる。固体状のエラストマーであるアクリロニトリル−ブタジエンゴムは、エポキシ樹脂との相溶性に優れることから好ましく用いられる。かかるエラストマーが、アミノ基やカルボキシル基などの、エポキシ基と反応する官能基を有するものであると、マトリクス樹脂の剛性を向上させるため、より好ましい。エラストマーの具体例としては、前記アクリロニトリル−ブタジエンゴムの他、ウレタンゴム、スチレン−ブタジエンゴムなど、またはこれらの混成物が挙げられる。またエラストマーの配合量としては、エポキシ樹脂配合物１００重量部に対して、１〜５重量部が良く、より好ましくは２〜３重量部が良い。１重量部未満では、前記した改良効果が充分に発揮されず、５重量部を超えるとマトリクス樹脂の剛性が損なわれてしまう。
【００３８】
なおエラストマーには、特殊な形態を有したものとして、アクリロニトリル−ブタジエンゴム、ウレタンゴム、スチレン−ブタジエンゴムなど、またはこれらの混成物よりなるコア成分と、ポリアクリレート、ポリアクリロニトリル、ポリスチレン、ポリメタクリル酸メチルなど、またはこれらの混合物よりなるシェル（コア成分の表面被覆）成分より構成される、コア／シェル型のエラストマーが、エポキシ樹脂組成物中への分散性が良好なことから好ましく用いられる。特に前記ゴムの架橋物よりなるエラストマーをコア成分に、ポリアクリレート、ポリアクリロニトリル、ポリスチレン、ポリメタクリル酸メチルなど、またはこれらの混合物をシェル成分に用いたコア／シェル型エラストマーは、マトリクス樹脂の剛性を顕著に高めることから、特に好ましく用いられる。
【００３９】
さらにまた無機粒子としては、アルミナ、カーボンブラック、カオリンクレー、グラファイト、ケイ酸アルミニウム、酸化スズ、酸化チタン、三酸化アンチモン、三酸化モリブデン、シリカ、ジルコニア、水酸化アルミニウム、水酸化マグネシウム、スメクタイト、セリサイト、タルク、炭酸カルシウム、炭酸マグネシウム、フェライト、マイカ、モンモリロナイト、硫化モリブデンなど、またはこれらの混合物が挙げられる。なかでもシリカ粒子は、エポキシ樹脂組成物に所謂チキソトロピー性を効果的に付与するため好ましい。またシリカ粒子には、二酸化ケイ素を基本骨格とし、粒子の表面がシラノール基で覆われている親水性タイプのものと、シラノール基の水素がアルキル基、シリル基等で置換されている疎水性タイプのものがあるが、後者の方がマトリクス樹脂に耐水性などの耐環境性を付与し得る観点から好ましく用いられる。
【００４０】
これら無機粒子の配合量は、エポキシ樹脂配合物１００重量部に対して、２〜１０重合部が良く、より好ましくは２〜７重量部が良い。２重量部未満では、樹脂の剛性を高める効果が充分に発揮されず、１０重量部を超えるとプリプレグのドレープが損なわれてしまう。
【００４１】
本発明によるエポキシ樹脂組成物をマトリクス樹脂として用いることにより、通常は、マトリクス樹脂との接着性に劣る、断面形状が真円状の補強繊維を用いても、マトリクス樹脂との間に高い接着性を発現することができる。また単繊維の断面形状が真円状の補強繊維を使用することによって、ボイドの発生など、望ましくない現象を排除でき、補強繊維分率を可能な限り高め得る一方で、局部への応力集中も緩和できることから、圧縮強度などの強度特性に優れた、高品位かつ大スケールの複合材料を得ることができる。また、その接着性は複合材料を長時間水中に浸漬した状態でも充分に強固なままに保持される。
【００４２】
本発明のプリプレグは、前記エポキシ樹脂組成物を先ず加熱して溶融せしめて後、樹脂が未硬化の間に離型紙上に均一に塗布して樹脂フィルムを作製し、その樹脂フィルムで補強繊維を両面から挟み込み、次いで樹脂を加圧、加熱しながら含浸させる方法などによって製造される。このときの補強繊維の形態や配列については、一方向に引き揃えられた長繊維、織物、組み紐、トウ、ニット、マットなどから、使用する部位や用途に応じて自由に選択することができる。またこのときの加熱温度については９０〜１５０℃が好ましい。加熱温度が、９０℃未満であると、補強繊維への樹脂の含浸が不完全になり、プリプレグのタックが過多になり取り扱い性が悪くなる。また１５０℃を超えると、補強繊維への樹脂の含浸は完全となるが、含浸の最中に樹脂の硬化反応が進行してしまうため、プリプレグのドレープが損なわれてしまう。またプリプレグにおける補強繊維分率は、５０〜８０重量％が好ましい。補強繊維分率が５０重量％未満であると、得られる複合材料において、圧縮強度などの強度特性が不足気味となり、また８０重量％を超えると補強繊維単糸同志が擦れ合うことによって繊維が疲労し、耐久性の良好な複合材料が得られない。
【００４３】
こうして得られたプリプレグは、室温での貯蔵安定性に優れており、室温下で１週間程度放置しても、タックやドレープの経時による変化は僅かであり、極めて取り扱いが容易である。
【００４４】
プリプレグから複合材料を製造する方法には、繊維の方向を少しずつ変えて、疑似的に等方性を持たせるようにして積層し、その後加熱することにより硬化せしめる方法が好ましく採用される。ここでの加熱温度は、１００〜１４０℃が好ましい。加熱温度が１００℃未満であると、マトリクス樹脂の硬化反応が不完全となり、得られる複合材料の耐熱性、耐環境性が不足気味となり、１４０℃を超えると、成形温度から室温まで冷却したときの熱収縮が無視できなくなり、この熱収縮を起こした箇所が複合材料における欠陥部位となり、局部に過大な応力が集中することの多い、航空機の主翼、尾翼、胴体などの１次構造材料や、前輪ドア、方向蛇、スポイラなどに代表される、大スケールの構造材料に複合材料を適用した場合、耐破壊性に劣ったものとなってしまい好ましくない。また成形時の加熱に要するエネルギーも増大してしまうため、好ましくない。
【００４５】
本発明における各材料の評価方法は、次の各項に示すとおりである。
（１）ＤＩＣＹ、ＤＤＳ粒子の平均粒子径の測定
ＤＩＣＹ、ＤＤＳ粒子を室温で真空乾燥して、含有水分率を０．２重量％以下とした後、粒度計を用いて粒子の平均粒子径を測定する。後述する実施例では粒度計として、レーザー回折式粒度計（島津製作所（株）製 ＳＡＬＤ−２００Ａ型）を用い、粒子を球体と想定して、その直径を平均粒子径として求めた。
【００４６】
（２）補強繊維の物性評価
補強繊維を繊維方向に垂直な方向から切断した後、その断面を走査型電子顕微鏡で拡大して写真撮影し、観察される断面形状に外接する半径Ｒの円と内接する半径ｒの円を描き、それら半径の比、Ｒ／ｒを断面の変形度とし、外接円の半径と内接円の半径の和、Ｒ＋ｒを断面の直径とする。
【００４７】
後述する実施例では、走査型電子顕微鏡として日立製作所（株）製 Ｓ−４０００型を用い、倍率１万倍、加速電圧１５ｋＶの条件下で、単繊維断面の拡大写真を得た。
【００４８】
さらに引張強度については、ＪＩＳ Ｒ７６０１に準拠して測定する。
【００４９】
【実施例】
以下、実施例によって本発明をより具体的に説明する。
【００５０】
（実施例１）
次に示す（１）〜（３）の手順で、エポキシ樹脂組成物、プリプレグ、炭素繊維強化複合材料を製造し、（４）に示す測定法で複合材料の圧縮強度を測定した。
【００５１】
（１）エポキシ樹脂組成物の調整
下記原料をニーダーを用いて混練し、エポキシ樹脂組成物を調整した。
【００５２】
テトラグリシジルアミン型エポキシ樹脂 ８０重量部
（住友化学（株）製 ＥＬＭ４３４）
ビスフェノールＡ型エポキシ樹脂 ２０重量部
（東都化成（株）製 ＹＤ−１２８）
ＤＩＣＹ ４重量部
４，４’−ＤＤＳ ８重量部
ＤＣＭＵ ５重量部
ＰＥＳ（ポリエーテルスルホン） ５重量部
（住友化学（株）製 Ｖｉｃｔｒｅｘ（登録商標）グレード５００３Ｐ）
ここで、次の方法で測定して、この樹脂組成物の吸湿時の剛性値として１０４０ＭＰａを得た。
【００５３】
まず、この樹脂組成物より、厚さ２ｍｍの樹脂板をオーブンを用いて加熱硬化法により作成する。次にこれを長さ５５ｍｍ、幅１０ｍｍの大きさに切り出し、次いで１００℃の沸騰水に約２０時間浸漬した後、沸騰水より取り出し、動的粘弾性法により８２℃における樹脂板の剛性率を測定し、吸湿時の樹脂の剛性率とする。なお、ここでは動的粘弾性法による測定装置として、レオメトリック社製ＡＲＥＳを使用した。
【００５４】
（２）プリプレグの製造
補強材として、東レ株式会社製炭素繊維「トレカ」（登録商標）Ｔ７００Ｓ（単繊維断面の変形度：１．０５、単繊維断面の直径：７μｍ、引張強度：４．９ＧＰａ）を用い、一方向に引き揃えた炭素繊維を、予め離型紙に塗布しておいたエポキシ樹脂フィルムで繊維を挟み込むようにして両面から覆い、加圧、加熱して樹脂を含浸せしめながらシート状プリプレグを製造した。
【００５５】
また、このとき１００℃における樹脂組成物の粘度は約１５Ｐａ・sであり、得られたプリプレグのタックとドレープは良好であった。
【００５６】
（３）炭素繊維強化複合材料の製造
シート状プリプレグを、６層構成になるよう一方向に積層した後、オートクレーブ内で、圧力０．２９４Ｐａ、温度１３５℃の条件下、１２０分間徐々に硬化せしめて炭素繊維強化複合材料を製造した。
【００５７】
（４）複合材料の圧縮強度の測定
得られた複合材料からＪＩＳ Ｋ７０７６のＡ法試験片の形状および寸法で試験片を切り出し、続いてこの試験片を７１℃に調節した温水に１４日間浸漬した後、この試験片を取り出し、雰囲気温度８２℃に調節した恒温槽内で０°圧縮強度を測定し、その値として１２４０ＭＰａを得た。
【００５８】
この実施例１で得られた複合材料は、航空機の構造材料に適用できる基準（上（４）に示す測定法で複合材料の０°圧縮強度＞１０００ＭＰａ）を満たしていた。
【００５９】
比較例１〜５については、実施例１の手順に準じて、エポキシ樹脂組成物、プリプレグ、炭素繊維強化複合材料を製造し、得られた複合材料を評価した。
【００６０】
実施例、比較例の結果を下表１に示す。
【００６２】
【表１】

注）表中数値は、エポキシ樹脂配合物１００重量部に対する重量部数を示す。
【００６３】
なお、表１において、アルファベットで略記した化合物は、それぞれ次に示す名称、化学構造式のものである。
【００６４】
ＥＬＭ４３４：テトラグリシジルアミン型エポキシ樹脂（住友化学（株）製）
【化２】

ＥＬＭ１００：グリシジルアミン型エポキシ樹脂（住友化学（株）製）
【化３】

ＭＴ０１６３：テトラグリシジルエーテル型エポキシ樹脂（チバ（株）製）
【化４】

Ｅｐ−１５４：フェノールノボラック型エポキシ樹脂（油化シェルエポキシ樹脂（株）製
【化５】

ＸＡＣ４１５２：オキサゾリドン環含有エポキシ樹脂（旭チバ（株）製）
【化６】

ＹＤ−１２８：ビスフェノールＡ型エポキシ樹脂（東都化成（株）製）
【化７】

注）上記化学構造式中、Ｇはグリシジル基（次式）を示す。
【００６５】
【化８】

ＤＩＣＹ：ジシアンジアミド
４、４’−ＤＤＳ：４、４’−ジアミノジフェニルスルホン
ＤＣＭＵ：３−（３−クロロフェニル）−１、１、−ジメチルウレア
ＨＤＩＺ：ヘプタデシルイミダゾール
ＰＥＩ：ポリエーテルイミド
（ジェネラル・エレクトリック（株）製 Ｕｌｔｅｍ（登録商標）グレード１０００）
ＰＥＳ：ポリエーテルスルホン
（住友化学（株）製 Ｖｉｃｔｒｅｘ グレード５００３Ｐ）
また、各実施例、比較例におけるＤＩＣＹ粒子の平均粒子径は７μｍ、また、実施例６における４、４’−ＤＤＳ微粒子の平均粒子径は１０μｍである。
【００６６】
【発明の効果】
本発明のプリプレグは、単繊維の断面形状が実質的に真円状の補強繊維とマトリクス樹脂との接着が従来になく強固なプリプレグであり、これが成形されて得られる繊維強化複合材料は、高い強度特性と共に、優れた耐熱性、耐環境性、耐久性を発現することで、特に航空機用構造材料に好適に使用することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a prepreg suitable for producing a fiber-reinforced composite material having excellent strength characteristics, heat resistance, and environmental resistance, and a structure for aircraft particularly formed by laminating and heating the prepreg. The present invention relates to a fiber reinforced composite material preferably applicable to the material.
[0002]
[Prior art]
Carbon fiber reinforced composite materials that use carbon fibers with excellent specific strength and specific elastic modulus as reinforcing fibers, and epoxy resins with good wettability and adhesiveness with the carbon fibers as matrix resins have excellent mechanical properties. , Aerospace / sports, sports / leisure, civil engineering / architecture, etc., and a wide variety of epoxy resin compositions have been created so far to provide the properties required for these applications. Many useful prepregs, intermediate materials, and composite materials are manufactured by combining with carbon fiber. In particular, in aircraft applications, a high level of performance is often required for composite materials used as structural materials.
[0003]
When applying fiber reinforced composite materials to aircraft structural materials, the strength properties should be considered to increase the compressive strength, and at the same time, the properties such as heat resistance, environmental resistance, and impact resistance should be improved. There is a need. As a means for this, it is necessary to use reinforcing fibers with high compressive strength and tensile strength for reinforcing fibers. On the other hand, with matrix resins, the matrix resin itself has high rigidity and appropriate toughness. It is necessary to. Furthermore, by making the adhesion between the reinforcing fibers and the matrix resin as high as possible, and by coordinating the properties of these materials, not only strength properties such as compressive strength, but also heat resistance, environmental resistance, impact resistance, etc. It is necessary to ensure that the properties are expressed effectively.
[0004]
A prepreg made of tetraglycidyl-type epoxy resin and diaminodiphenylsulfone as a curing agent as a matrix resin has been commonly used in the production of aircraft structural materials since the carbon fiber and the matrix resin exhibit high adhesion. It was. However, such a resin composition can be applied to aircraft structural materials because the temperature required for heating when curing the prepreg to form a molded article is as high as about 180 ° C. and a large amount of energy is required for heating. While a fiber-reinforced composite material having excellent high strength characteristics can be obtained after molding, a prepreg capable of realizing significant energy saving than before has been strongly desired when a molded product is produced.
[0005]
As for the reinforcing fiber, the cross-sectional shape of the single fiber is a perfect circle, an ellipse, an egg, an empty bean, a trefoil, etc. The amount of resin to be used can be minimized and the effect of dispersing applied load stress is also manifested, which is preferable in terms of strength characteristics, but because the so-called anchor effect of the fiber is reduced, the adhesion between the fiber and the matrix resin As a result, there was a problem that a composite material having good strength characteristics could not be obtained.
[0006]
As an example in which these conflicting effects are compatible and a composite material having as high a strength property as possible is obtained, Japanese Patent Application Laid-Open No. 8-81572 discloses that single fibers of carbon fibers are densely arranged in a cross section perpendicular to the fiber direction. In order to produce a filled prepreg, a carbon fiber having a substantially circular cross section of a single fiber, a modified epoxy resin obtained by modifying a bisphenol A type epoxy resin with diaminodiphenyl sulfone, dicyandiamide as a curing agent, and a curing catalyst A prepreg comprising a matrix resin using dichlorophenylurea as a composite material is disclosed, but a composite material produced from such a prepreg has an adhesion developed between the carbon fiber and the matrix resin when the resin is dry. The composite material is sufficiently high and the strength characteristics of the composite material are good. When the load is applied at this time, there is a problem that separation occurs at the interface region between the carbon fiber and the matrix resin, and the composite material is damaged. For aircrafts that require both strength characteristics and weather resistance It was difficult to apply to structural materials.
[0007]
The inventors have obtained a fiber-reinforced composite material with significantly lower energy consumption than conventional prepregs comprising a reinforcing fiber having a substantially circular cross-sectional shape and an epoxy resin composition that adheres firmly to the reinforcing fiber. The present inventors have found that this fiber-reinforced composite material obtained by molding can be applied to aircraft structural materials that require high strength properties, heat resistance, and environmental resistance without problems, and have led to the present invention.
[0008]
[Problems to be solved by the invention]
The present invention uses a reinforcing fiber having a substantially circular cross-sectional shape, and can maintain high adhesion between the reinforcing fiber and the matrix resin even in a humid heat environment, and can produce a molded product with lower energy consumption than in the past. An object of the present invention is to provide a prepreg capable of exhibiting high strength properties, heat resistance, and environmental resistance, which can be obtained, and the fiber reinforced composite material obtained by molding can be highly desired particularly for aircraft structural materials. .
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the prepreg of the present invention has the following configuration. That is, at least the following components [A], [B], [C], [D], [E]The, With respect to 100 parts by weight of the component [A], the component [B] is 3 to 5 parts by weight and the component [D] is 5 to 15 parts by weight.A prepreg is characterized in that the epoxy resin composition is impregnated into a reinforcing fiber having a substantially circular cross-sectional shape of a single fiber.
[0010]
[A]: Epoxy resin compound in which 60 parts by weight or more of tetraglycidylamine type epoxy resin is compounded with respect to 100 parts by weight of the epoxy resin compound
[B]: particulate dicyandiamide
[C]: Urea compound
[D]: Diaminodiphenyl sulfone
[E]: Thermoplastic resin
  Moreover, in order to solve the said subject, the fiber reinforced composite material of this invention has the following structure. That is, it is a fiber-reinforced composite material formed by laminating the prepreg and curing it by heating at 100 to 140 ° C.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0012]
The present invention relates to a prepreg that can be suitably used for manufacturing a large-scale material typified by an aircraft structural material, and a fiber-reinforced composite material formed by molding the prepreg.
[0013]
In order to increase the strength characteristics of the composite material obtained after molding as much as possible and to provide the high-level characteristics required for aircraft structural materials, the prepreg of the present invention has a substantially circular cross section of a single fiber. It is necessary to use reinforcing fibers that are About the diameter of the single fiber cross section of this reinforcement fiber, 5-9 micrometers is good, More preferably, 6-8 micrometers is good. When the cross-sectional diameter is less than 5 μm, the hardener fine particles are difficult to enter the reinforcing fiber, so that the adhesiveness with the matrix resin is reduced. When the cross-sectional diameter exceeds 9 μm, the total contact area between the reinforcing fiber and the matrix resin is reduced. It becomes small and the adhesiveness between both will fall. Note that the cross-sectional shape referred to here is substantially a perfect circle, and usually the ratio R / r of the radius R of the circle circumscribing the cross-sectional shape to the radius r of the inscribed circle is 1 to 1.1. It means that there is.
[0014]
The reinforcing fiber preferably has a resin-impregnated strand tensile strength (hereinafter referred to as tensile strength) of 4 GPa or more. If the tensile strength is less than 4 GPa, the strength characteristics of the resulting composite material may be insufficient, making it difficult to apply to structural materials for aircraft. However, if the tensile strength of the reinforcing fiber is about 10 GPa at the maximum, it is often sufficient to achieve the effects of the present invention. The reinforcing fiber is preferably a carbon fiber from the viewpoint of adhesion to an epoxy resin and strength properties, but other silicon carbide fibers, glass fibers, aramid fibers, boron fibers, high-strength polyethylene fibers, and the like are also mixed. Fine yarn may be used. Further, as the molding material made of reinforcing fibers, those obtained by blending each as a single fiber can be suitably used.
[0015]
As the main component of the component [A] in the present invention, among the glycidyl type epoxy resins such as glycidyl ether type epoxy resin and glycidyl amine type epoxy resin, the latter glycidyl amine type epoxy resin has adhesiveness to the reinforcing fiber. It is effective from the viewpoint of improvement, and in particular, a glycidylamine type epoxy resin in which two glycidylamino groups are present in a repeating unit corresponding to one monomer molecule (hereinafter referred to as a repeating unit), that is, a tetraglycidylamine type Epoxy resins are more effective. Those having one glycidylamino group present in the repeating unit tend to have poor adhesion between the reinforcing fiber and the matrix resin, and those having three or more glycidylamino groups present in the repeating unit are matrix resins. As a result, a composite material having high impact resistance cannot be obtained.
[0016]
Examples of the tetraglycidylamine type epoxy resin include tetraglycidylmetaxylenediamine, tetraglycidyldiaminodiphenylmethane, tetraglycidylbisaminomethylcyclohexane, tetraglycidylaminophenyldiisopropylbenzene, and mixtures thereof, among which tetraglycidyldiamino Diphenylmethane is remarkably effective in enhancing the adhesion between the reinforcing fiber and the matrix resin, and can be preferably used because it improves the strength characteristics, heat resistance, and environmental resistance of the resulting composite material.
[0017]
The compounding amount of the resin needs to be 60 parts by weight or more, preferably 70 parts by weight or more, and more preferably 80 parts by weight or more with respect to 100 parts by weight of the epoxy resin compound. When the blending amount is less than 60 parts by weight, when the resulting composite material is immersed in water, if water enters the interface region between the reinforcing fiber and the matrix resin, the adhesive force in the interface region is maintained. It becomes impossible and the strength characteristic of the composite material is impaired. In addition, when an epoxy resin other than the tetraglycidylamine type epoxy resin described later is included in the component [A], the amount of the tetraglycidylamine type epoxy resin in the component [A] is 97 parts by weight or less. To do.
[0018]
Moreover, the epoxy resin other than the following tetraglycidylamine type epoxy resins is blended with the constituent element [A] as necessary, together with the tetraglycidylamine type epoxy resin.
[0019]
That is, bisphenol A type epoxy resin (epoxy resin having bisphenol A as a precursor), bisphenol F type epoxy resin (epoxy resin having bisphenol F as a precursor), bisphenol S type epoxy resin (epoxy having bisphenol S as a precursor) Resin) and other novolac epoxy resins such as cresol novolac epoxy resin (epoxy resin with cresol novolac as a precursor), phenol novolac epoxy resin (epoxy resin with phenol novolac as a precursor), In addition, tetraglycidyl ether type epoxy resin (epoxy resin with tetraphenol as a precursor), triglycidyl ether type epoxy resin (epoxy resin with triphenol as a precursor), resorci Type epoxy resin (epoxy resin with resorcinol as a precursor), naphthalene type epoxy resin (epoxy resin with dihydroxynaphthalene as precursor), biphenyl type epoxy resin (epoxy resin with dihydroxybiphenyl as precursor), fluorene type Epoxy resin (epoxy resin with bishydroxyphenylfluorene as a precursor), dicyclopentadiene type epoxy resin (epoxy resin composed of a condensate of dicyclopentadiene and phenol), epoxy resin having an oxazolidone ring, or a mixture thereof is there.
[0020]
Here, the epoxy resin having an oxazolidone ring is generally represented by the following structural chemical formula.
[0021]
[Chemical 1]

Where R₁, R₂, R_ThreeIs a hydrocarbon group that may contain oxygen and R₁And R_ThreeMay be the same or different, and a bisphenol group (-O-Ph-CR in the hydrocarbon group).₂-Ph-O-CH₂CH (OH) CH₂-; Ph = C₆H_Four, R = CH_ThreeOr the thing containing H) is common.
[0022]
An epoxy resin having an oxazolidone ring is reacted with an isocyanate compound and an epoxy compound in the presence of a catalyst such as a tertiary amine, a quaternary ammonium salt, a phosphonium compound, or a lithium compound by the method disclosed in JP-A-5-43655. Can be obtained. Examples of the isocyanate compound include isophorone diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and mixtures thereof. Epoxy compounds include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol. S diglycidyl ether or the like, or a mixture thereof.
[0023]
Among the epoxy resins other than the tetraglycidylamine type epoxy resin, the bisphenol type epoxy resin is preferable in order to improve the toughness of the resin while maintaining high adhesiveness with the reinforcing fiber. The cyclopentadiene type epoxy resin is particularly preferably used as an epoxy resin other than the tetraglycidylamine type epoxy resin because it has an effect of moderately suppressing tackiness of the prepreg while maintaining the heat resistance and environmental resistance of the obtained composite material. .
[0024]
Furthermore, when the above-mentioned epoxy resin having an oxazolidone ring is used as an epoxy resin other than the tetraglycidylamine type epoxy resin, the adhesion to the reinforcing fiber is further enhanced, and the strength characteristics such as compressive strength, heat resistance, and environmental resistance. Is preferable because a more excellent fiber-reinforced composite material can be obtained.
[0025]
It should be noted that the amount of the epoxy resin other than the tetraglycidylamine-type epoxy resin is preferably as small as possible in the component [A], but it is 3 to 40 parts by weight with respect to 100 parts by weight of the epoxy resin compound. The amount is preferably 3 to 30 parts by weight, more preferably 3 to 20 parts by weight.
[0026]
  Component [B] in the present invention is particulate dicyandiamide(Hereafter referred to as DICY)It is. In the present invention,By using diaminodiphenyl sulfone (hereinafter referred to as DDS) as a constituent element [D], which will be described later, in combination with DICY as a curing agent at a specific blending amount, the reinforcing fiber and the matrix resin are more firmly bonded. . That is, the prepreg of the present invention consisting of an epoxy resin composition in which 3 to 5 parts by weight of DICY and 5 to 15 parts by weight of DDS is blended with 100 parts by weight of the epoxy resin composition is prominent between the reinforcing fibers. By exhibiting an adhesive effect, a fiber-reinforced composite material having more excellent strength characteristics such as compressive strength, heat resistance, and environmental resistance can be obtained.
[0027]
  DICY is a particulate compound belonging to the amine-based curing agent and is hardly soluble in an epoxy resin composition corresponding to a bulk in a low temperature region, but dissolves at 100 ° C. or higher and starts a reaction with the epoxy resin. . For this reason, epoxy resin compositions and prepregs that use DICY as a curing agent have particularly good storage stability..
[0028]
The average particle diameter of the DICY particles is preferably 1 to 15 μm, more preferably 3 to 13 μm, and still more preferably 5 to 10 μm. When the average particle size of the DICY particles is less than 1 μm, dissolution of DICY in the epoxy resin composition is promoted too much, and the curing reaction may proceed even at a temperature near room temperature, and the epoxy resin composition or prepreg If the average particle size of the DICY particles is larger than 15 μm, even if the particles are impregnated with the resin while applying pressure and heating to the reinforcing fibers when the prepreg is manufactured, the reinforcement Since it becomes difficult for DICY to enter the fiber bundle, the adhesiveness between the reinforcing fiber and the matrix resin is not sufficiently exhibited, and a composite material having excellent strength properties such as compressive strength cannot be obtained after molding.
[0030]
DDS is a particulate compound belonging to an aromatic amine curing agent, and there are structural isomers depending on the substitution position of the amino group on the aromatic ring. In the present invention, any isomer can be used, but the characteristics of the matrix resin and the resulting composite material can be controlled by changing the type of isomer. For example, 4, 4'-DDS has particularly excellent heat resistance, and 3, 3'-DDS has particularly excellent rigidity. The average particle diameter of DDS is preferably 1 to 15 μm, more preferably 5 to 13 μm, and further preferably 8 to 13 μm for the same reason as DICY.
[0031]
Component [C] in the present invention is a urea compound. When a urea compound is used as a curing accelerator, an epoxy resin composition excellent in both storage stability and adhesive properties with reinforcing fibers can be obtained. When a tertiary amine compound is used instead of a urea compound as a curing accelerator, the storage stability of the epoxy resin composition or prepreg is impaired. When an imidazole compound is used, the adhesion between the reinforcing fiber and the matrix resin is lost. Tends to decrease.
[0032]
As urea compounds, 3-phenyl-1,1-dimethylurea, 3- (3-chlorophenyl) -1,1, -dimethylurea (hereinafter referred to as DCMU), 3- (3,4-dichlorophenyl) -1 1-dimethylurea (hereinafter referred to as HDIZ), or a mixture thereof. Moreover, 2-10 weight part is good for the compounding quantity with respect to 100 weight part of epoxy resin compounds of a urea compound, More preferably, 3-8 weight part, More preferably, 4-6 weight part is good. If the blending amount of the urea compound is less than 2 parts by weight, the adhesion between the reinforcing fiber and the matrix resin tends to decrease. If it exceeds 10 parts by weight, the curing promoting action becomes excessive, and the epoxy resin composition The storage stability of objects and prepregs is impaired.
[0033]
Furthermore, the epoxy resin composition according to the present invention includes a prepreg that controls the rheological properties of the resin in an uncured state, improves the rigidity and toughness of the matrix resin, controls the tack, and improves the adhesion between the reinforcing fiber and the matrix resin. In addition to the above-described components, the following thermoplastic resin, elastomer, and inorganic particles are preferably blended as an improving agent.
[0034]
As thermoplastic resins, polyacetal, polyamide, polyamideimide, polyarylene oxide, polyarylate, polyimide, polyethylene, polyethylene terephthalate, polyethylene naphthalate, polyetherimide, polyetheretherketone, polyethersulfone, polyvinylchloride, polycarbonate, Polyvinyl acetate, polystyrene, polysulfone, polytetrafluoroethylene, polyhydroxy ether, polyvinyl acetal, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl formal, polyphenylene oxide, polybutylene terephthalate, polyphenylene sulfide, polypropylene, polybenzimidazole, polymethyl methacrylate, etc. Is mentioned.
[0035]
These thermoplastic resins can be blended singly or in combination, and among them, the polyamide resin improves the toughness of the matrix resin and improves the impact resistance of the resulting composite material. Therefore, the polyimide resin and the polyethersulfone resin are particularly preferable because the adhesive strength between the reinforcing fiber and the matrix resin is strengthened while the rigidity of the matrix resin is kept high, and the compressive strength of the obtained composite material is greatly improved. Used.
[0036]
The blending amount of these thermoplastic resins is preferably 5 to 20 polymer parts, more preferably 5 to 15 parts by weight, and further preferably 5 to 12 parts by weight with respect to 100 parts by weight of the epoxy resin composition. When the amount is less than 5 parts by weight, the above-described improvement effect is not sufficiently exhibited. When the amount exceeds 20 parts by weight, the heat resistance is impaired.
[0037]
The elastomer may be liquid or solid, but the latter is preferably used from the viewpoint of maintaining the rigidity of the matrix resin. Acrylonitrile-butadiene rubber, which is a solid elastomer, is preferably used because of its excellent compatibility with epoxy resins. It is more preferable that the elastomer has a functional group that reacts with an epoxy group, such as an amino group or a carboxyl group, because the rigidity of the matrix resin is improved. Specific examples of the elastomer include the acrylonitrile-butadiene rubber, urethane rubber, styrene-butadiene rubber, and the like, or a mixture thereof. The amount of the elastomer is preferably 1 to 5 parts by weight, more preferably 2 to 3 parts by weight with respect to 100 parts by weight of the epoxy resin composition. If it is less than 1 part by weight, the above-described improvement effect is not sufficiently exhibited, and if it exceeds 5 parts by weight, the rigidity of the matrix resin is impaired.
[0038]
It should be noted that the elastomer has a special form, such as acrylonitrile-butadiene rubber, urethane rubber, styrene-butadiene rubber, or a core component made of a mixture thereof, polyacrylate, polyacrylonitrile, polystyrene, polymethacrylic acid. A core / shell type elastomer composed of a shell (core surface coating) component composed of methyl or the like or a mixture thereof is preferably used because of its good dispersibility in the epoxy resin composition. In particular, a core / shell type elastomer using a cross-linked rubber elastomer as a core component, polyacrylate, polyacrylonitrile, polystyrene, polymethyl methacrylate, etc., or a mixture thereof as a shell component has the rigidity of the matrix resin. Since it raises notably, it is used especially preferably.
[0039]
Furthermore, inorganic particles include alumina, carbon black, kaolin clay, graphite, aluminum silicate, tin oxide, titanium oxide, antimony trioxide, molybdenum trioxide, silica, zirconia, aluminum hydroxide, magnesium hydroxide, smectite, selenium. Sites, talc, calcium carbonate, magnesium carbonate, ferrite, mica, montmorillonite, molybdenum sulfide, etc., or mixtures thereof. Of these, silica particles are preferable because they effectively impart so-called thixotropic properties to the epoxy resin composition. Silica particles include a hydrophilic type whose basic skeleton is silicon dioxide and the surface of the particle is covered with a silanol group, and a hydrophobic type in which the hydrogen of the silanol group is substituted with an alkyl group, a silyl group, etc. However, the latter is preferably used from the viewpoint of imparting water resistance and other environmental resistance to the matrix resin.
[0040]
The blending amount of these inorganic particles is preferably 2 to 10 polymer parts, more preferably 2 to 7 parts by weight with respect to 100 parts by weight of the epoxy resin composition. If it is less than 2 parts by weight, the effect of increasing the rigidity of the resin is not sufficiently exhibited, and if it exceeds 10 parts by weight, the drape of the prepreg is impaired.
[0041]
By using the epoxy resin composition according to the present invention as a matrix resin, it is usually inferior in adhesiveness to the matrix resin, and even if reinforcing fibers having a perfect circular cross section are used, high adhesion to the matrix resin is achieved. Can be expressed. Also, by using reinforcing fibers with a single fiber cross-sectional shape, it is possible to eliminate undesirable phenomena such as voids and increase the reinforcing fiber fraction as much as possible, while also concentrating stress on the local area. Since it can be relaxed, a high-quality and large-scale composite material excellent in strength properties such as compressive strength can be obtained. Further, the adhesiveness is maintained sufficiently strong even when the composite material is immersed in water for a long time.
[0042]
In the prepreg of the present invention, the epoxy resin composition is first heated and melted, and then uniformly applied onto a release paper while the resin is uncured to produce a resin film. It is produced by a method of sandwiching from both sides and then impregnating the resin with pressure and heating. The form and arrangement of the reinforcing fibers at this time can be freely selected from long fibers, woven fabrics, braids, tows, knits, mats, and the like that are aligned in one direction, depending on the part to be used and the application. Moreover, about the heating temperature at this time, 90-150 degreeC is preferable. When the heating temperature is less than 90 ° C., the impregnation of the resin into the reinforcing fiber becomes incomplete, the tackiness of the prepreg becomes excessive, and the handleability deteriorates. If the temperature exceeds 150 ° C., the resin is completely impregnated into the reinforcing fibers, but the resin curing reaction proceeds during the impregnation, so that the prepreg drape is impaired. The reinforcing fiber fraction in the prepreg is preferably 50 to 80% by weight. If the reinforcing fiber fraction is less than 50% by weight, the resulting composite material has insufficient strength properties such as compressive strength, and if it exceeds 80% by weight, the fibers become fatigued due to friction between the reinforcing fiber single yarns. Therefore, a composite material with good durability cannot be obtained.
[0043]
The prepreg thus obtained is excellent in storage stability at room temperature, and even if it is left at room temperature for about one week, the change with time of tack and drape is slight, and it is very easy to handle.
[0044]
As a method for producing a composite material from a prepreg, a method in which the direction of fibers is changed little by little so as to have a pseudo isotropic property, and then cured by heating is preferably employed. The heating temperature here is preferably 100 to 140 ° C. When the heating temperature is less than 100 ° C., the curing reaction of the matrix resin becomes incomplete, and the resulting composite material has insufficient heat resistance and environmental resistance. When the heating temperature exceeds 140 ° C., the molding material is cooled from the molding temperature to room temperature. The thermal contraction of the aircraft can no longer be ignored, the location where the thermal contraction has occurred becomes a defect site in the composite material, and excessive stress is often concentrated locally, primary structural materials such as aircraft main wing, tail wing, fuselage, When a composite material is applied to a large-scale structural material typified by a front wheel door, a direction snake, a spoiler, etc., it is not preferable because it is inferior in fracture resistance. Further, the energy required for heating during molding increases, which is not preferable.
[0045]
The evaluation method of each material in the present invention is as shown in the following items.
(1) Measurement of average particle diameter of DICY and DDS particles
The DICY and DDS particles are vacuum-dried at room temperature so that the moisture content is 0.2% by weight or less, and then the average particle size of the particles is measured using a particle size meter. In Examples to be described later, a laser diffraction type particle size meter (SALD-200A type, manufactured by Shimadzu Corporation) was used as a particle size meter, assuming that the particle was a sphere, and its diameter was determined as an average particle size.
[0046]
(2) Physical property evaluation of reinforcing fiber
After cutting the reinforcing fiber from the direction perpendicular to the fiber direction, the cross section is magnified with a scanning electron microscope and photographed, and a circle of radius R circumscribed and a circle of radius r inscribed are drawn on the observed cross sectional shape. The ratio of the radii, R / r is the degree of deformation of the cross section, the radius of the circumscribed circle and the radius of the inscribed circle, and R + r is the diameter of the cross section.
[0047]
In Examples described later, an S-4000 model manufactured by Hitachi, Ltd. was used as a scanning electron microscope, and an enlarged photograph of a single fiber cross section was obtained under conditions of a magnification of 10,000 and an acceleration voltage of 15 kV.
[0048]
Further, the tensile strength is measured according to JIS R7601.
[0049]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
[0050]
Example 1
The epoxy resin composition, the prepreg, and the carbon fiber reinforced composite material were produced by the following procedures (1) to (3), and the compressive strength of the composite material was measured by the measurement method shown in (4).
[0051]
(1) Preparation of epoxy resin composition
The following raw materials were kneaded using a kneader to prepare an epoxy resin composition.
[0052]
Tetraglycidylamine type epoxy resin80Parts by weight
(ELM434 manufactured by Sumitomo Chemical Co., Ltd.)
Bisphenol A type epoxy resin20Parts by weight
(YD-128, manufactured by Tohto Kasei Co., Ltd.)
DICY 4 parts by weight
4,4'-DDS 8 parts by weight
DCMU 5 parts by weight
PES (Polyethersulfone)5Parts by weight
(Victrex (registered trademark) grade 5003P manufactured by Sumitomo Chemical Co., Ltd.)
Here, the rigidity value at the time of moisture absorption of this resin composition is measured by the following method.1040MPa was obtained.
[0053]
  First, a resin plate having a thickness of 2 mm is prepared from this resin composition by a heat curing method using an oven. Next, this was cut into a size of 55 mm in length and 10 mm in width, then immersed in boiling water at 100 ° C. for about 20 hours, then taken out from boiling water, and the rigidity of the resin plate at 82 ° C. was determined by dynamic viscoelasticity. Measure and use the resin rigidity at the time of moisture absorption. Here, as a measuring device by the dynamic viscoelastic method, A made by Rheometric Co., Ltd.RES was used.
[0054]
(2) Manufacture of prepreg
As a reinforcing material, carbon fiber “Torayca” (registered trademark) T700S manufactured by Toray Industries, Inc. (degree of single fiber cross section deformation: 1.05, single fiber cross section diameter: 7 μm, tensile strength: 4.9 GPa) is used in one direction. The sheet-like prepreg was manufactured by covering the carbon fiber from the both sides with the epoxy resin film previously applied to the release paper so that the fiber was sandwiched from both sides and applying pressure and heating to impregnate the resin.
[0055]
At this time, the viscosity of the resin composition at 100 ° C. was about 15 Pa · s, and the prepreg obtained had good tack and drape.
[0056]
(3) Manufacture of carbon fiber reinforced composite materials
The sheet-like prepreg was laminated in one direction so as to have a six-layer structure, and then was gradually cured in an autoclave under a pressure of 0.294 Pa and a temperature of 135 ° C. for 120 minutes to produce a carbon fiber reinforced composite material.
[0057]
(4) Measurement of compressive strength of composite material
  A test piece was cut out from the obtained composite material in the shape and size of the JIS K7076 A method test piece, and subsequently immersed in warm water adjusted to 71 ° C. for 14 days. Measure the 0 ° compressive strength in a thermostat adjusted to 82 ° C,1240MPa was obtained.
[0058]
The composite material obtained in Example 1 satisfied the standards applicable to aircraft structural materials (0 ° compressive strength of composite material> 1000 MPa according to the measurement method shown in (4) above).
[0059]
  About Comparative Examples 1-5, the epoxy resin composition, the prepreg, and the carbon fiber reinforced composite material were manufactured according to the procedure of Example 1, and the obtained composite material was evaluated.
[0060]
The results of Examples and Comparative Examples are shown in Table 1 below.
[0062]
[Table 1]

Note) The numerical values in the table indicate the number of parts by weight with respect to 100 parts by weight of the epoxy resin compound.
[0063]
  Table1The compounds abbreviated with alphabets have the following names and chemical structural formulas, respectively.
[0064]
ELM434: Tetraglycidylamine type epoxy resin (manufactured by Sumitomo Chemical Co., Ltd.)
[Chemical 2]

ELM100: Glycidylamine type epoxy resin (manufactured by Sumitomo Chemical Co., Ltd.)
[Chemical Formula 3]

MT0163: Tetraglycidyl ether type epoxy resin (manufactured by Ciba)
[Formula 4]

Ep-154: phenol novolac type epoxy resin (Oilized Shell Epoxy Resin Co., Ltd.)
[Chemical formula 5]

XAC4152: Oxazolidone ring-containing epoxy resin (Asahi Ciba Co., Ltd.)
[Chemical 6]

YD-128: Bisphenol A type epoxy resin (manufactured by Toto Kasei Co., Ltd.)
[Chemical 7]

Note) In the above chemical structural formula, G represents a glycidyl group (following formula).
[0065]
[Chemical 8]

DICY: Dicyandiamide
4,4'-DDS: 4,4'-diaminodiphenylsulfone
DCMU: 3- (3-chlorophenyl) -1,1, -dimethylurea
HDIZ: heptadecylimidazole
PEI: Polyetherimide
(Ultem (registered trademark) grade 1000 manufactured by General Electric Co., Ltd.)
PES: Polyethersulfone
(Victrex grade 5003P manufactured by Sumitomo Chemical Co., Ltd.)
The average particle size of DICY particles in each Example and Comparative Example is 7 μm, and the average particle size of 4,4′-DDS fine particles in Example 6 is 10 μm.
[0066]
【The invention's effect】
The prepreg of the present invention is a prepreg in which the cross-sectional shape of a single fiber is substantially unprecedented in the bonding between a reinforcing fiber and a matrix resin, and the fiber-reinforced composite material obtained by molding this is high. By exhibiting excellent heat resistance, environmental resistance and durability as well as strength characteristics, it can be suitably used particularly for aircraft structural materials.

Claims (6)

At least the following components [A], [B], [C], [D], the [E], with respect to component [A] 100 parts by weight, 3 to 5 parts by weight of component [B], structure A prepreg characterized in that an epoxy resin composition containing 5 to 15 parts by weight of an element [D] is impregnated into a reinforcing fiber having a substantially circular cross-sectional shape of a single fiber.
[A]: Epoxy resin blend in which 60 parts by weight or more of tetraglycidylamine type epoxy resin is blended with 100 parts by weight of epoxy resin blend [B]: Particulate dicyandiamide [C]: Urea compound
[D]: Diaminodiphenyl sulfone
[E]: Thermoplastic resin In the component [A], the amount of the tetraglycidylamine type epoxy resin is 60 to 97 parts by weight with respect to 100 parts by weight of the epoxy resin compound, and the component [A] includes a tetraglycidylamine type epoxy. the prepreg according to 請 Motomeko 1 epoxy resin other than the resin that is 3 to 40 parts by weight. The tetraglycidyl amine type epoxy resin other than the epoxy resin, bisphenol type epoxy resins, novolak type epoxy resins, at least one epoxy resin der Ru請 Motomeko 2 prepreg according selected from epoxy resin having an oxazolidone ring. The epoxy resin composition, prepreg according to any one of 請 Motomeko 1-3 that is part of the inorganic particles. The prepreg according to any one of claims 1 to 4, comprising 5 to 12 parts by weight of the component [E] with respect to 100 parts by weight of the component [A]. A fiber-reinforced composite material obtained by laminating the prepreg according to any one of claims 1 to 5 and curing and molding by heating at 100 to 140 ° C.